Oak Canyon Action Memo

EPA Pesticide Factsheets

This memorandum requests approval for a time-critical removal action at the 27 residential properties that compose the Oak Canyon Site located in the Village of Paguate, Pueblo of Laguna, near Cibola County, New Mexico.

Bridge 232, view looking east in Rock Creek Canyon at ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Bridge 23-2, view looking east in Rock Creek Canyon at Milepost 23.23 - Camas Prairie Railroad, Second Subdivision, From Spalding in Nez Perce County, through Lewis County, to Grangeville in Idaho County, Spalding, Nez Perce County, ID

A view over Rock Creek Canyon off Bridge 232 looking ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

A view over Rock Creek Canyon off Bridge 23-2 looking north at Milepost 23.26 - Camas Prairie Railroad, Second Subdivision, From Spalding in Nez Perce County, through Lewis County, to Grangeville in Idaho County, Spalding, Nez Perce County, ID

Compilation of ground-water quality data for selected wells in Elmore, Owyhee, Ada, and Canyon counties, Idaho, 1945 through 1982

USGS Publications Warehouse

Parliman, D.J.

1982-01-01

Well-inventory and groundwater-quality data for 665 sites with a total of 1,318 chemical analyses were compiled from Elmore, Owyhee, Ada, and Canyon Counties. Data are sorted by water temperature (less than 20 degrees Celsius is considered nonthermal; 20 degrees Celcius or greater is considered thermal) to facilitate their use.

5. Long view from canyon edge, west of the overlook, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. Long view from canyon edge, west of the overlook, showing relationship of Mather Point to neighboring south rim projections; view to southeast - Mather Point Overlook, South Entrance Road, Grand Canyon Village, Coconino County, AZ

Digital geologic map of the Thirsty Canyon NW quadrangle, Nye County, Nevada

USGS Publications Warehouse

Minor, S.A.; Orkild, P.P.; Sargent, K.A.; Warren, R.G.; Sawyer, D.A.; Workman, J.B.

1998-01-01

This digital geologic map compilation presents new polygon (i.e., geologic map unit contacts), line (i.e., fault, fold axis, dike, and caldera wall), and point (i.e., structural attitude) vector data for the Thirsty Canyon NW 7 1/2' quadrangle in southern Nevada. The map database, which is at 1:24,000-scale resolution, provides geologic coverage of an area of current hydrogeologic and tectonic interest. The Thirsty Canyon NW quadrangle is located in southern Nye County about 20 km west of the Nevada Test Site (NTS) and 30 km north of the town of Beatty. The map area is underlain by extensive layers of Neogene (about 14 to 4.5 million years old [Ma]) mafic and silicic volcanic rocks that are temporally and spatially associated with transtensional tectonic deformation. Mapped volcanic features include part of a late Miocene (about 9.2 Ma) collapse caldera, a Pliocene (about 4.5 Ma) shield volcano, and two Pleistocene (about 0.3 Ma) cinder cones. Also documented are numerous normal, oblique-slip, and strike-slip faults that reflect regional transtensional deformation along the southern part of the Walker Lane belt. The Thirsty Canyon NW map provides new geologic information for modeling groundwater flow paths that may enter the map area from underground nuclear testing areas located in the NTS about 25 km to the east. The geologic map database comprises six component ArcINFO map coverages that can be accessed after decompressing and unbundling the data archive file (tcnw.tar.gz). These six coverages (tcnwpoly, tcnwflt, tcnwfold, tcnwdike, tcnwcald, and tcnwatt) are formatted here in ArcINFO EXPORT format. Bundled with this database are two PDF files for readily viewing and printing the map, accessory graphics, and a description of map units and compilation methods.

Geology of an Ordovician stratiform base-metal deposit in the Long Canyon Area, Blaine County, Idaho

USGS Publications Warehouse

Otto, B.R.; Zieg, G.A.

2003-01-01

In the Long Canyon area, Blaine County, Idaho, a strati-form base-metal-bearing gossan is exposed within a complexly folded and faulted sequence of Ordovician strata. The gossan horizon in graptolitic mudrock suggests preservation of bedded sulfides that were deposited by an Ordovician subaqueous hydrothermal system. Abrupt thickness changes and geochemi-cal zoning in the metal-bearing strata suggest that the gossan is near the source of the hydrothermal system. Ordovician sedimentary rocks at Long Canyon represent a coarsening-upward section that was deposited below wave base in a submarine depositional environment. The lowest exposed rocks represent deposition in a starved, euxinic basin and over-lying strata represent a prograding clastic wedge of terrigenous and calcareous detritus. The metalliferous strata are between these two types of strata. Strata at Long Canyon have been deformed by two periods of thrust faulting, at least three periods of normal faulting, and two periods of folding. Tertiary extensional faulting formed five subhorizontal structural plates. These low-angle fault-bounded plates truncate Sevier-age and possibly Antler-age thrust faults. The presence of gossan-bearing strata in the four upper plates suggests that there was only minor, although locally complex, stratigraphic displacement and rotation. The lack of correlative strata in the lowest plate suggests the displacement was greater than 2000 ft. The metalliferous strata were exposed to surface weathering, oxidation, and erosion prior to and during deposition of the Eocene Challis Volcanic Group. The orientations of erosional canyons formed during this early period of exposure were related to the orientations of Sevier-age thrust faults, and stream-channel gravel was deposited in the canyons. During this and subsequent intervals of exposure, sulfidic strata were oxi-dized to a minimum depth of 700 ft.

Overview of the Colorado River Canyon from the helicopter pad. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Overview of the Colorado River Canyon from the helicopter pad. View of the Nevada side where new bridge will cross canyon, view northwest - Hoover Dam, Spanning Colorado River at Route 93, Boulder City, Clark County, NV

Hydrologic and water-quality data at Government Canyon State Natural Area, Bexar County, Texas, 2002-10

USGS Publications Warehouse

Banta, J. Ryan; Slattery, Richard N.

2012-01-01

The U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture Natural Resources Conservation Service, the Edwards Aquifer Authority, and the Texas Parks and Wildlife Department, collected rainfall, streamflow, evapotranspiration, and stormflow water-quality data at the Laurel Canyon Creek watershed, within the Government Canyon State Natural Area, Bexar County, Tex. The purpose of the data collection was to support evaluations of the effects of brush management conservation practices on components of the hydrologic budget and water quality. One component of brush management was to take endangered wildlife into consideration, specifically the golden-cheeked warbler (Dendroica chrysoparia). Much of the area that may have been considered for brush management was left intact to protect habitat for the golden-cheeked warbler. The area identified for brush management was approximately 10 percent of the study watershed. The hydrologic data presented here (2002–10) represent pre- and post-treatment periods, with brush management treatment occurring from winter 2006–07 to spring 2008.

4. VISTA POINT AND INTERPRETIVE PLAQUE AT LEE VINING CANYON. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. VISTA POINT AND INTERPRETIVE PLAQUE AT LEE VINING CANYON. NOTE ROAD CUT ON CANYON WALL. LOOKING NNE. GIS: N-37 56 30.3 / 119 13 44.8 - Tioga Road, Between Crane Flat & Tioga Pass, Yosemite Village, Mariposa County, CA

Geologic Map of the Upper Parashant Canyon and Vicinity, Mohave County, Northwestern Arizona

USGS Publications Warehouse

Billingsley, George H.; Harr, Michelle L.; Wellmeyer, Jessica L.

2000-01-01

Introduction The geologic map of the upper Parashant Canyon area covers part of the Colorado Plateau and several large tributary canyons that make up the western part of Arizona's Grand Canyon. The map is part of a cooperative U.S. Geological Survey and National Park Service project to provide geologic information for areas within the newly established Grand Canyon/Parashant Canyon National Monument. Most of the Grand Canyon and parts of the adjacent plateaus have been geologically mapped; this map fills in one of the remaining areas where uniform quality geologic mapping was needed. The geologic information presented may be useful in future related studies as to land use management, range management, and flood control programs for federal and state agencies, and private concerns. The map area is in a remote region of the Arizona Strip, northwestern Arizona about 88 km south of the nearest settlement of St. George, Utah. Elevations range from about 1,097 m (3,600 ft) in Parashant Canyon (south edge of map area) to 2,145 m (7,037 ft) near the east-central edge of the map area. Primary vehicle access is by dirt road locally known as the Mount Trumbull road; unimproved dirt roads and jeep trails traverse various parts of the map area. Travel on the Mount Trumbull road is possible with 2-wheel-drive vehicles except during wet conditions. Extra fuel, two spare tires and extra food and water are highly recommended when traveling in this remote area. The map area includes about 26 sections of land belonging to the State of Arizona, about 40 sections of private land, and a small strip of the Lake Mead National Recreation Area (southeast edge of the map area). The private land is mainly clustered around the abandoned settlement of Mt. Trumbull, locally known as Bundyville, and a few sections are scattered in the upper Whitmore Canyon area just south of Bundyville. Lower elevations within the canyons support a sparse growth of sagebrush, cactus, grass, creosote bush, and a

Geochemical map of the Chama River Canyon Wilderness and contiguous roadless area, Rio Arriba County, New Mexico

USGS Publications Warehouse

Ridgley, Jennie L.

1986-01-01

The Chama River Canyon Wilderness, in Rio Arriba County, north-central New Mexico, covers 50,300 acres (20,364 hectares) within the Coyote and Cuba Ranger Districts of the Santa Fe National Forest and the Canjilon Ranger District of the Carson National Forest. In 1979 the U.S. Forest Service, under the Forest Service Roadless Area Review and Evaluation (RARE II) program, designated three additional areas, contiguous to the wilderness, for further planning to assess wilderness characteristics. These areas, totaling 4,800 acres (1,945 hectares), were collectively designated Roadless area 03098; they have since been dropped from consideration. 

Late Holocene earthquake history of the Brigham City segment of the Wasatch fault zone at the Hansen Canyon, Kotter Canyon, and Pearsons Canyon trench sites, Box Elder County, Utah

USGS Publications Warehouse

DuRoss, Christopher B.; Personius, Stephen F.; Crone, Anthony J.; McDonald, Greg N.; Briggs, Richard W.

2012-01-01

Of the five central segments of the Wasatch fault zone (WFZ) having evidence of recurrent Holocene surface-faulting earthquakes, the Brigham City segment (BCS) has the longest elapsed time since its most recent surface-faulting event (~2.1 kyr) compared to its mean recurrence time between events (~1.3 kyr). Thus, the BCS has the highest time-dependent earthquake probability of the central WFZ. We excavated trenches at three sites––the Kotter Canyon and Hansen Canyon sites on the north-central BCS and Pearsons Canyon site on the southern BCS––to determine whether a surface-faulting earthquake younger than 2.1 ka occurred on the BCS. Paleoseismic data for Hansen Canyon and Kotter Canyon confirm that the youngest earthquake on the north-central BCS occurred before 2 ka, consistent with previous north-central BCS investigations at Bowden Canyon and Box Elder Canyon. At Hansen Canyon, the most recent earthquake is constrained to 2.1–4.2 ka and had 0.6–2.5 m of vertical displacement. At Kotter Canyon, we found evidence for two events at 2.5 ± 0.3 ka and 3.5 ± 0.3 ka, with an average displacement per event of 1.9–2.3 m. Paleoseismic data from Pearsons Canyon, on the previously unstudied southern BCS, indicate that a post-2 ka earthquake ruptured this part of the segment. The Pearsons Canyon earthquake occurred at 1.2 ± 0.04 ka and had 0.1–0.8 m of vertical displacement, consistent with our observation of continuous, youthful scarps on the southern 9 km of the BCS having 1–2 m of late Holocene(?) surface offset. The 1.2-ka earthquake on the southern BCS likely represents rupture across the Weber–Brigham City segment boundary from the penultimate Weber-segment earthquake at about 1.1 ka. The Pearsons Canyon data result in a revised length of the BCS that has not ruptured since 2 ka (with time-dependent probability implications), and provide compelling evidence of at least one segment-boundary failure and multi-segment rupture on the central WFZ. Our

Geology of the Canyon Reservoir site on the Guadalupe River, Comal County, Texas

USGS Publications Warehouse

George, William O.; Welder, Frank A.

1955-01-01

In response to a request by Colonel Harry O. Fisher, District Engineer of the Fort Worth District of the Corps of Engineers, United States Army (letter of Dec. 13, 1954), a reconnaissance investigation was made of the geology of the Canyon (F-1) reservoir site on the Guadalupe River in Comal County, Tex. The purpose of the investigation was to study the geology in relation to possible leakage - particularly leakage of water that might then be lost from the drainage area of the Guadalupe River - and to add to the general knowledge of the ground-water hydrology of the San Antonio area. The dam (F-1) was originally designed for flood control and conservation only, with provision for the addition of a power unit if feasible. Since the completion of the investigation by the Corps of Engineers, the city of San Antonio has expressed an interest in the reservoir as a possible source of public water supply. The Corps of Engineers has made a thorough engineering and geologic study of the dam site (Corps of Engineers, 1950), which has Congressional approval. The geology and water resources of Comal County have been studied by George (1952). The rocks studied are those within the reservoir area and generally below the 1,000-foot contour as shown on the Smithson Valley quadrangle of the U.S. Geological Survey.

14. MAIN CANAL CANAL CHECKGATES, JUST BELOW DARK CANYON ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

14. MAIN CANAL - CANAL CHECKGATES, JUST BELOW DARK CANYON SIPHON, VIEW TO NORTHEAST - Carlsbad Irrigation District, Main Canal, 4 miles North to 12 miles Southeast of Carlsbad, Carlsbad, Eddy County, NM

Geologic map and upper Paleozoic stratigraphy of the Marble Canyon area, Cottonwood Canyon quadrangle, Death Valley National Park, Inyo County, California

USGS Publications Warehouse

Stone, Paul; Stevens, Calvin H.; Belasky, Paul; Montañez, Isabel P.; Martin, Lauren G.; Wardlaw, Bruce R.; Sandberg, Charles A.; Wan, Elmira; Olson, Holly A.; Priest, Susan S.

2014-01-01

This geologic map and pamphlet focus on the stratigraphy, depositional history, and paleogeographic significance of upper Paleozoic rocks exposed in the Marble Canyon area in Death Valley National Park, California. Bedrock exposed in this area is composed of Mississippian to lower Permian (Cisuralian) marine sedimentary rocks and the Jurassic Hunter Mountain Quartz Monzonite. These units are overlain by Tertiary and Quaternary nonmarine sedimentary deposits that include a previously unrecognized tuff to which we tentatively assign an age of late middle Miocene (~12 Ma) based on tephrochronologic analysis, in addition to the previously recognized Pliocene tuff of Mesquite Spring. Mississippian and Pennsylvanian rocks in the Marble Canyon area represent deposition on the western continental shelf of North America. Mississippian limestone units in the area (Tin Mountain, Stone Canyon, and Santa Rosa Hills Limestones) accumulated on the outer part of a broad carbonate platform that extended southwest across Nevada into east-central California. Carbonate sedimentation was interrupted by a major eustatic sea-level fall that has been interpreted to record the onset of late Paleozoic glaciation in southern Gondwana. Following a brief period of Late Mississippian clastic sedimentation (Indian Springs Formation), a rise in eustatic sea level led to establishment of a new carbonate platform that covered most of the area previously occupied by the Mississippian platform. The Pennsylvanian Bird Spring Formation at Marble Canyon makes up the outer platform component of ten third-order (1 to 5 m.y. duration) stratigraphic sequences recently defined for the regional platform succession. The regional paleogeography was fundamentally changed by major tectonic activity along the continental margin beginning in middle early Permian time. As a result, the Pennsylvanian carbonate shelf at Marble Canyon subsided and was disconformably overlain by lower Permian units (Osborne Canyon and

Mineral resources of the San Rafael Swell Wilderness Study Areas, including Muddy Creek, Crack Canyon, San Rafael Reef, Mexican Mountain, and Sids Mountain Wilderness Study Areas, Emery County, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartsch-Winkler, S.; Dickerson, R.P.; Barton, H.W.

1990-09-01

This paper reports on the San Rafael Swell Wilderness Study areas, which includes the Muddy Creek, Crack Canyon, San Rafael Reef, Mexican Mountain, and Sids Mountain Wilderness Study Areas, in Emery County, south-central Utah. Within and near the Crack Canyon Wilderness Study Area are identified subeconomic uranium and vanadium resources. Within the Carmel Formation are inferred subeconomic resources of gypsum in the Muddy Creek, San Rafael Reef, and Sids Mountain Wilderness Study Areas. Other commodities evaluated include geothermal energy, gypsum, limestone, oil and gas, sand and gravel, sandstone, semiprecious gemstones, sulfur petrified wood, and tar sand.

3. VIEW OF DIABLO CANYON LOOKING DOWNSTREAM FROM THE VALVE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. VIEW OF DIABLO CANYON LOOKING DOWNSTREAM FROM THE VALVE HOUSE AT ELEVATION 1044, 1989. - Skagit Power Development, Diablo Dam, On Skagit River, 6.9 miles upstream from Newhalem, Newhalem, Whatcom County, WA

View of the Colorado River Canyon showing lower portal road ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of the Colorado River Canyon showing lower portal road in background taken from the rim of Hoover Dam, view south - Hoover Dam, Spanning Colorado River at Route 93, Boulder City, Clark County, NV

77 FR 74470 - Notice of Availability for the Draft Environmental Impact Statement for the Gregory Canyon...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-14

... DEPARTMENT OF DEFENSE Department of the Army, Corps of Engineers Notice of Availability for the Draft Environmental Impact Statement for the Gregory Canyon Landfill Project, San Diego County, CA... Draft Environmental Impact Statement (EIS) for the proposed Gregory Canyon Landfill Project in San Diego...

View of the Colorado River Canyon form the Nevada side ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of the Colorado River Canyon form the Nevada side showing the Nevada rim towers and portions of US 93, view south - Hoover Dam, Spanning Colorado River at Route 93, Boulder City, Clark County, NV

View of Nevada side of Colorado River Canyon showing US ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of Nevada side of Colorado River Canyon showing US 93 in foreground, transmission towers and static towers in background, view west - Hoover Dam, Spanning Colorado River at Route 93, Boulder City, Clark County, NV

Mineral Resources of the Hells Canyon Study Area, Wallowa County, Oregon, and Idaho and Adams Counties, Idaho

USGS Publications Warehouse

Simmons, George C.; Gualtieri, James L.; Close, Terry J.; Federspiel, Francis E.; Leszcykowski, Andrew M.

2007-01-01

Field studies supporting the evaluation of the mineral potential of the Hells Canyon study area were carried out by the U.S. Geological Survey and the U.S. Bureau of Mines in 1974-76 and 1979. The study area includes (1) the Hells Canyon Wilderness; (2) parts of the Snake River, Rapid River, and West Fork Rapid River Wild and Scenic Rivers; (3) lands included in the second Roadless Area Review and Evaluation (RARE II); and (4) part of the Hells Canyon National Recreation Area. The survey is one of a series of studies to appraise the suitability of the area for inclusion in the National Wilderness Preservation System as required by the Wilderness Act of 1964. The spectacular and mineralized area covers nearly 950 mi2 (2,460 km2) in northeast Oregon and west-central Idaho at the junction of the Northern Rocky Mountains and the Columbia Plateau.

View of Nevada side of Colorado River Canyon showing US ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of Nevada side of Colorado River Canyon showing US 93, Visitor Center parking lot, transmission lines, and static towers in background, view west - Hoover Dam, Spanning Colorado River at Route 93, Boulder City, Clark County, NV

Geology of the Shinarump No. 1 uranium mine, Seven Mile Canyon area, Grand County, Utah

USGS Publications Warehouse

Finch, Warren Irvin

1954-01-01

The geology of the Shinarump No. 1 uranium mine, located about 12 miles northwest of Moab, Utah, in the Seven Mile Canyon area, Grand County, Utah, was studied to determine the habits, ore controls, and possible origin of the deposit. Rocks of Permian, Triassic, and Jurassic age crop out in the area mapped, and uranium deposits are found in three zones in the lower 25 feet of the Chinle formation of Late Triassic age. The Shinarump No. 1 mine, which is in the lowermost zone, is located on the west flank of the Moab anticline near the Moab fault. The Shinarump No. 1 uranium deposit consists of discontinuous lenticular layers of mineralized rock, irregular in outline, that, in general, follow the bedding. Ore minerals, mainly uraninite, impregnate the rock. High-grade ore seams of uraninite and chalcocite occur along bedding planes. Uraninite formed later than, or simultaneous with, most sulfides, and the chalcocite may be of two ages, with some being later than uraninite. Uraninite and chalcocite are concentrated in the more poorly sorted parts of siltstones. In the Seven Mile Canyon area guides to ore inferred from the study of the Shinarump No. 1 deposit are the presence of bleached siltstone, carbonaceous matter, and copper sulfides. Results of spectrographic analysis indicate that the mineralizing solutions contained important amounts of barium, vanadium, uranium, and copper, as well as lesser amounts of strontium, chromium, boron, yttrium, lead, and zinc. The origin of the Shinarump No. 1 deposit is thought to be hydrothermal.

Geology of the Shinarump No. 1 uranium mine, Seven Mile Canyon area, Grand County, Utah

USGS Publications Warehouse

Finch, Warren Irvin

1953-01-01

The Shinarump No. 1 uranium mine is located about 12 miles northwest of Moab, Utah, in the Seven Mile Canyon area, Grand County, Utah. A study was made of the geology of the Shinarump No. 1 mine in order to determine the habits, ore controls, and possible origin of the deposit. Rocks of Permain, Triassic, and Jurassic age crop out in the area mapped. Uranium deposits are found in three zones in the lower 25 feet of the Upper Triassic Chinle formation. The Shinarump No. 1 mine, which is in the lowermost zone, is located on the west flank of the Moab anticline near the Moab fault. The Shinarump No. 1 uranium deposit consists of discontinuous lenticular layers of mineralized rock, irregular in outline, that, in general, follow the bedding. Ore minerals, mainly uranite, impregnate the rock. High-grade seams of uranite and chalcocite occur along bedding planes. Formation of unraninite is later than or simultaneous with most sulfides. Chalcocite may be of two ages, with some being later than uraninite. Uraninite and chalcocite are concentrated in the poorer sorted parts of siltstones. Guides to ore in the Seven Mile Canyon area inferred from the study of the Shinarump No. 1 deposit are the presence of bleached siltstone, copper sulfides, and carbonaceous matter. Results of spectrographic analysis indicated that the mineralizing solutions contained important amounts of barium, vanadium, uranium, and copper as well as lesser amounts of strontium, chromium, boron, yttrium, lead, and zinc. The origin of the Shinarump No. 1 deposit is thought to be hydrothermal, dated as later or early.

View of Nevada side of Colorado River Canyon taken from ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of Nevada side of Colorado River Canyon taken from Lower Portal Road looking up towards area where new bridge will be located, view northwest - Hoover Dam, Spanning Colorado River at Route 93, Boulder City, Clark County, NV

View of Arizona side of Colorado River Canyon taken from ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of Arizona side of Colorado River Canyon taken from Lower Portal Road looking up towards area where new bridge will be located, view northeast - Hoover Dam, Spanning Colorado River at Route 93, Boulder City, Clark County, NV

33. VIEW OF TIOGA ROAD DESCENDING LEE VINING CANYON. SAME ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

33. VIEW OF TIOGA ROAD DESCENDING LEE VINING CANYON. SAME VIEW AS CA-149-3. LOOKING ESE. GIS: N-37 56 58.2 / W-119 13 28.1 - Tioga Road, Between Crane Flat & Tioga Pass, Yosemite Village, Mariposa County, CA

9. COULTERVILLE ROAD VIEW AND MERCED RIVER CANYON. NOTE CUT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. COULTERVILLE ROAD VIEW AND MERCED RIVER CANYON. NOTE CUT FACE OF STANDING ROCK AT RIGHT. LOOKING N. GIS: N-37 42 52.1 / W-119 43 17.5 - Coulterville Road, Between Foresta & All-Weather Highway, Yosemite Village, Mariposa County, CA

33. SAR1, LOOKING DOWN CANYON OVER TAILRACE CONSTRUCTION. EEC print ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

33. SAR-1, LOOKING DOWN CANYON OVER TAILRACE CONSTRUCTION. EEC print no. G-C-01-00269, no date. Photograph by Benjamin F. Pearson. - Santa Ana River Hydroelectric System, SAR-1 Powerhouse, Redlands, San Bernardino County, CA

Adobe unlocks Cherry Canyon, other zones in prolific Barstow unit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brewster, J.

1979-08-01

Recent discoveries by Adobe Oil and Gas Corp. in the Barstow unit skirting the Pecos River near Pecos, Texas have extended the Cherry Canyon play approx. 10 miles west in Ward County. In February, Adobe reported an oil discovery, 10 Barstow, drilled between No. 9 and No. 11 (gas wells) in section 34. The well reestablished Cherry Canyon oil production in the Scott field with a potential of 149 bpd of oil and a gor of 1540:1 or gas flow of 230 mcfd. Perforations were from 5827 to 6092 ft. The explanation of the anomaly of an oil well sandwichedmore » between 2 gas wells all producing from the same formation, is that Cherry Canyon consists of lensitic sands, not necessarily connected, that can yield gas and oil in substantially different proportions.« less

Preliminary report on the White Canyon area, San Juan county, Utah

USGS Publications Warehouse

Benson, William E.; Trites, Albert F.; Beroni, Ernest P.; Feeger, John A.

1952-01-01

The White Canyon area, in the central part of San Juan County, Utah, consists of approximately two 15-minute quadrangles. Approximately 75 square miles have been mapped by the Geological Survey on a scale of 1 inch equals 1 mile, using a combined aerial photography-plane table method. Structure contours were drawn on top of the Organ Rock member of the Cutler formation. Parts of the Gonway and North Point claims, 1/4 mile east of the Happy Jack mine, were mapped in detail. The principal objectives of the investigations were: (1) to establish ore guides; (2) to select areas favorable for exploration; and (3) to map the general geology and to determine the regional relationships of the uranium deposits. The White Canyon area is comprised of sedimentary rocks of Carboniferous to Jurassic age, more than 2,000 feet thick, having a regional dip of 1° to 2° SW. The nearest igneous rocks are in the Henry Mountains about 7 miles west of the northern part of the area; The Shinarump conglomerate of the late Triassic age, the principal ore horizon in the White Canyon area, consists of lenticular beds of sandstone, conglomeratic sandstone, conglomerate, clay, and siltstone. The Shinarump conglomerate, absent in places, is as much as 75 feet thick. The sandstones locally contain molds of logs and fragments of altered volcanic ash. Some of the logs have been replaced by copper and uranium minerals and iron oxides. The clay and siltstone underlie and are interbedded with the sandstone, and are most common in channels that cut into the underlying Moenkopi formation. The Shinarump conglomerate contains reworked Moenkopi siltstone fragments, clay balls, carbonized wood, and pebbles of quarts, quartzite, and chert. Jointing is prominent in the Western part of the mapped area. The three most prominent joint trends are due east, N. 65°-75° W., and N. 65°-75° E. All joints have vertical dips. The red beds are bleached along some joints, especially those that trend N. 65°-75° W

75 FR 27550 - Electrical Interconnection of the Juniper Canyon I Wind Project

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-17

... Canyon I Wind Project AGENCY: Bonneville Power Administration (BPA), Department of Energy (DOE). ACTION: Notice of Availability of Record of Decision (ROD). SUMMARY: The Bonneville Power Administration (BPA... County, Washington. To interconnect the Wind Project, BPA will expand an existing substation (Rock Creek...

Preliminary Report on the White Canyon Area, San Juan County, Utah

USGS Publications Warehouse

Benson, William Edward Barnes; Trites, A.F.; Beroni, E.P.; Feeger, J.A.

1952-01-01

The White Canyon area in San Juan County, Utah, contains known deposits of copper-uranium ore and is currently being mapped and studied by the Geological Survey. To date, approximately 75 square miles, or about 20 percent of the area, has been mapped on a scale 1 inch=1 mile. The White Canyon area is underlain by more than 2,000 feet of sedimentary rocks, Carboniferous to Jurassic(?) in age. The area is on the flank of the Elk Ridge anticline, and the strata have a regional dip of 1 deg to 2 deg SW. The Shinarump conglomerate of Late Triassic age is the principal ore-bearing formation. The Shinarump consists of lenticular beds of sandstone, conglomeratic sandstone, clay, and siltstone, and ranges in thickness from a feather edge to as much as 75 feet. Locally the sandstones contain silicified and carbonized wood and fragments of charcoal. These vegetal remains are especially common in channel-fill deposits. Jointing is prominent in the western part of the area, and apparently affects all formations. Adjacent to the joints some of the redbeds in the sequence are bleached. Deposits of copper-uranium minerals have been found in the Moenkopi, Shinarump, and Chinle formations, but the only production of ore has been from the Shinarump conglomerate. The largest concentration of these minerals is in the lower third of the Shinarump, and the deposits seem to be controlled in part by ancient channel fills and in part by fractures. Locally precipitation of the copper and uranium minerals apparently has been aided by charcoal and clays. Visible uranium minerals include both hard and soft pitchblende and secondary hydrosulfates, phosphates, and silicates. In addition, unidentified uranium compounds are present in carbonized wood and charcoal, and in veinlets of hydrocarbons. Base-metal sulfides have been identified in all prospects that extend beyond the oxidized zone. Secondary copper minerals in the oxidized zone include the hydrous sulfates and carbonates, and possibly

The Prado Dam and Reservoir, Riverside and San Bernardino Counties, California

DTIC Science & Technology

1989-10-31

Riverside and San Bernardino counties. It exemplifies current awareness of the need for broad based, regional planning efforts which transcend the...Pacific Ocean (Post 1928:31). En route to the sea, the river passes through two constrictions, both named Santa Ana Canyon . The Upper Santa Ana Canyon ... Canyon is located about 30 miles from the sea and is formed by the Puente Hills to the northwest and the Santa Ana Mountains to the southeast (Figure

Environmental Assessment and Finding of No Significant Impact: Curecanti-Lost Canyon 230-kV Transmission Line Reroute Project, Montrose County, Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

N /A

2000-03-20

The Department of Energy (DOE), Western Area Power Administration (Western) is proposing to reroute a section of the Curecanti-Lost Canyon 230-kilovolt (kV) transmission line, in Montrose County, Colorado. A portion of the transmission line, situated 11 miles southeast of Montrose, Colorado, crosses Waterdog Peak, an area of significant geologic surface activity, which is causing the transmission line's lattice steel towers to shift. This increases stress to structure hardware and conductors, and poses a threat to the integrity of the transmission system. Western proposes to relocate the lattice steel towers and line to a more geologically stable area. The existing sectionmore » of transmission line and the proposed relocation route cross Bureau of Land Management and private land holdings.« less

Summary of data acquisition and field operations: Terra Resources, Anderson Canyon No. 3-17, Lincoln County, Wyoming; Terra Resources, North Anderson Canyon No. 40-16, Sweetwater County, Wyoming. Topical report, August 1989

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1989-08-01

A summary is presented of open-hole data collected on two cooperative wells for the GRI Tight Gas Sands Program. The overall objective of gathering well data in the Frontier Formation is to identify and evaluate technological problems in formation evaluation and hydraulic fracturing. Open-hole data acquisition is emphasized for the Anderson Canyon No. 3-17, a full cooperative well (i.e., coring, logging, cased-hole stress testing, fracture monitoring). Data collected on the North Anderson Canyon No. 40-16, a partial cooperative well (i.e., logging only), is described in an appendix.

Digital Database of Selected Aggregate and Related Resources in Ada, Boise, Canyon, Elmore, Gem, and Owyhee Counties, Southwestern Idaho

USGS Publications Warehouse

Moyle, Phillip R.; Wallis, John C.; Bliss, James D.; Bolm, Karen D.

2004-01-01

The U.S. Geological Survey (USGS) compiled a database of aggregate sites and geotechnical sample data for six counties - Ada, Boise, Canyon, Elmore, Gem, and Owyhee - in southwest Idaho as part of a series of studies in support of the Bureau of Land Management (BLM) planning process. Emphasis is placed on sand and gravel sites in deposits of the Boise River, Snake River, and other fluvial systems and in Neogene lacustrine deposits. Data were collected primarily from unpublished Idaho Transportation Department (ITD) records and BLM site descriptions, published Army Corps of Engineers (ACE) records, and USGS sampling data. The results of this study provides important information needed by land-use planners and resource managers, particularly in the BLM, to anticipate and plan for demand and development of sand and gravel and other mineral material resources on public lands in response to the urban growth in southwestern Idaho.

Relative abundance and distribution of fishes within an established Area of Critical Environmental Concern, of the Amargosa River Canyon and Willow Creek, Inyo and San Bernardino Counties, California

USGS Publications Warehouse

Scoppettone, G. Gary; Hereford, Mark E.; Rissler, Peter H.; Johnson, Danielle M.; Salgado, Antonio

2011-01-01

The Amargosa River Canyon of San Bernardino and Inyo County, California, has been designated by the Bureau of Land Management as an Area of Critical Environmental Concern, due in part to its unique flora and fauna. As a task of the Area of Critical Environmental Concern implementation plan, a survey of native fishes was conducted from June 21 to August 12, 2010. Geographic Information System tools were used to map sampling locations, which were spaced at 50-meter intervals. Global Positioning Systems were used to locate sampling stations, and stations with adequate water for successful trapping were sampled with baited minnow traps. Amargosa River pupfish (Cyprinodon nevadensis amargosae) and speckled dace (Rhinichthys osculus spp.) were widespread throughout Armargosa River Canyon. Throughout the study area 8,558 pupfish were captured at 194 stations; 3,472 speckled dace were captured at 210 stations; 238 red-swamp crayfish (Procambarus clarkia) were captured at 83 stations; and 1,095 western mosquitofish (Gambusia affinus) were captured at 110 stations. Pupfish were most abundant in open water habitat with native riparian vegetation, and they were significantly less abundant where the stream was completely covered by cattails or where saltcedar (Tamarix sp.) dominated the riparian corridor. There was no relationship between stream cover and speckled dace distribution. Non-native western mosquitofish and red-swamp crayfish densities were significantly higher in stream reaches dominated by saltcedar. The continued spread of saltcedar threatens to negatively affect pupfish and potentially reduce speckled dace abundance throughout the Amargosa River Canyon. This study can serve as baseline information for observing native fish populations in the future, as related to potential changes to the Amargosa River Canyon ecosystem.

Ground-water conditions in the Grand County area, Utah, with emphasis on the Mill Creek-Spanish Valley area

USGS Publications Warehouse

Blanchard, Paul J.

1990-01-01

The Grand County area includes all of Grand County, the Mill Creek and Pack Creek drainages in San Juan County, and the area between the Colorado and Green Rivers in San Juan County. The Grand County area includes about 3,980 square miles, and the Mill Creek-Spanish Valley area includes about 44 square miles. The three principal consolidated-rock aquifers in the Grand County area are the Entrada, Navajo, and Wingate aquifers in the Entrada Sandstone, the Navajo Sandstone, and the Wingate Sandstone, and the principal consolidated-rock aquifer in the Mill Creek-Spanish Valley area is the Glen Canyon aquifer in the Glen Canyon Group, comprised of the Navajo Sandstone, the Kayenta Formation, and the Wingate Sandstone.Recharge to the Entrada, Navajo, and Glen Canyon aquifers typically occurs where the formations containing the aquifers crop out or are overlain by unconsolidated sand deposits. Recharge is enhanced where the sand deposits are saturated at a depth of more than about 6 feet below the land surface, and the effects of evaporation begin to decrease rapidly with depth. Recharge to the Wingate aquifer typically occurs by downward movement of water from the Navajo aquifer through the Kayenta Formation, and primarily occurs where the Navajo Sandstone, Kayenta Formation, and the Wingate Sandstone are fractured.

Faulting apparently related to the 1994 Northridge, California, earthquake and possible co-seismic origin of surface cracks in Potrero Canyon, Los Angeles County, California

USGS Publications Warehouse

Catchings, R.D.; Goldman, M.R.; Lee, W.H.K.; Rymer, M.J.; Ponti, D.J.

1998-01-01

Apparent southward-dipping, reverse-fault zones are imaged to depths of about 1.5 km beneath Potrero Canyon, Los Angeles County, California. Based on their orientation and projection to the surface, we suggest that the imaged fault zones are extensions of the Oak Ridge fault. Geologic mapping by others and correlations with seismicity studies suggest that the Oak Ridge fault is the causative fault of the 17 January 1994 Northridge earthquake (Northridge fault). Our seismically imaged faults may be among several faults that collectively comprise the Northridge thrust fault system. Unusually strong shaking in Potrero Canyon during the Northridge earthquake may have resulted from focusing of seismic energy or co-seismic movement along existing, related shallow-depth faults. The strong shaking produced ground-surface cracks and sand blows distributed along the length of the canyon. Seismic reflection and refraction images show that shallow-depth faults may underlie some of the observed surface cracks. The relationship between observed surface cracks and imaged faults indicates that some of the surface cracks may have developed from nontectonic alluvial movement, but others may be fault related. Immediately beneath the surface cracks, P-wave velocities are unusually low (<400 m/sec), and there are velocity anomalies consistent with a seismic reflection image of shallow faulting to depths of at least 100 m. On the basis of velocity data, we suggest that unconsolidated soils (<800 m/sec) extend to depths of about 15 to 20 m beneath our datum (<25 m below ground surface). The underlying rocks range in velocity from about 1000 to 5000 m/sec in the upper 100 m. This study illustrates the utility of high-resolution seismic imaging in assessing local and regional seismic hazards.

Ecological baseline studies in Los Alamos and Guaje Canyons County of Los Alamos, New Mexico. A two-year study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foxx, T.S.

1995-11-01

During the summers of 1993 and 1994, the Biological Resource Evaluations Team (BRET) of the Environmental Protection Group (ESH-8) conducted baseline studies within two canyon systems, Los Alamos and Guaje Canyons. Biological data was collected within each canyon to provide background and baseline information for Ecological Risk models. Baseline studies included establishment of permanent vegetation plots within each canyon along the elevational gradient. Then, in association with the various vegetation types, surveys were conducted for ground dwelling insects, birds, and small mammals. The stream channels associated with the permanent vegetation plots were characterized and aquatic macroinvertebrates collected within the streammore » monthly throughout a six-month period. The Geographic Position System (GPS) in combination with ARC INFO was used to map the study areas. Considerable data was collected during these surveys and are summarized in individual chapters.« less

Origin of Florida Canyon and the role of spring sapping on the formation of submarine box canyons

USGS Publications Warehouse

Paull, Charles K.; Spiess, Fred N.; Curray, Joseph R.; Twichell, David C.

1990-01-01

Florida Canyon, one of a series of major submarine canyons on the southwestern edge of the Florida Platform, was surveyed using GLORIA, SeaBeam, and Deep-Tow technologies, and it was directly observed during three DSRV Alvin dives. Florida Canyon exhibits two distinct morphologies: a broad V-shaped upper canyon and a deeply entrenched, flat-floored, U-shaped lower canyon. The flat- floored lower canyon extends 20 km into the Florida Platform from the abyssal Gulf. The lower canyon ends abruptly at an ∼3 km in diameter semicircular headwall that rises 750 m with a >60° slope angle to the foot of the upper canyon. The sides of the lower canyon are less steep than its headwall and are characterized by straight faces that occur along preferred orientations and indicate a strong joint control. The upper canyon is characterized by a gently sloping, straight V-shaped central valley cut into a broad terrace. The flat floor of the upper canyon continues as terraces along the upper walls of the lower canyon. On the flanks of the upper canyon, there are five >50-m-deep, >0.5-km-wide, closed sink-hole-like depressions which indicate subsurface dissolution within the platform. The origin of the lower canyon is difficult to explain with traditional models of submarine canyon formation by external physical processes. The movement of ground water, probably with high salinities and reduced compounds along regional joints, may have focused the corrosive force of submarine spring sapping at the head of the lower canyon to produce the canyon's present shape.

Geologic map and digital database of the Apache Canyon 7.5' quadrangle, Ventura and Kern counties, California

USGS Publications Warehouse

Stone, Paul; Cossette, P.M.

2000-01-01

The Apache Canyon 7.5-minute quadrangle is located in southwestern California about 55 km northeast of Santa Barbara and 65 km southwest of Bakersfield. This report presents the results of a geologic mapping investigation of the Apache Canyon quadrangle that was carried out in 1997-1999 as part of the U.S. Geological Survey's Southern California Areal Mapping Project. This quadrangle was chosen for study because it is in an area of complex, incompletely understood Cenozoic stratigraphy and structure of potential importance for regional tectonic interpretations, particularly those involving the San Andreas fault located just northwest of the quadrangle and the Big Pine fault about 10 km to the south. In addition, the quadrangle is notable for its well-exposed sequences of folded Neogene nonmarine strata including the Caliente Formation of Miocene age from which previous workers have collected and described several biostratigraphically significant land-mammal fossil assemblages. During the present study, these strata were mapped in detail throughout the quadrangle to provide an improved framework for possible future paleontologic investigations. The Apache Canyon quadrangle is in the eastern part of the Cuyama 30-minute by 60-minute quadrangle and is largely part of an erosionally dissected terrain known as the Cuyama badlands at the east end of Cuyama Valley. Most of the Apache Canyon quadrangle consists of public lands in the Los Padres National Forest.

Geology of Raymond Canyon, Sublette Range, western Wyoming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shoemaker, W.A.

1984-07-01

Raymond Canyon is located on the west side of the Sublette Range, Lincoln County, Wyoming. The study area is just east of the Idaho border and 10 mi (16 km) southeast of Geneva, Idaho. Formations exposed range in age from Late Pennsylvanian to Tertiary (Pliocene) and include: the lower part of the Wells Formation (Pennsylvanian, total thickness 720 ft or 219 m); the upper part of the Wells Formation and the Phosphoria Formation (both Permian, 153-210 ft or 47-64 m); the Dinwoody Formation (185 ft or 56 m); Woodside Shale (540 ft or 165 m); Thaynes Limestone (2345 ft ormore » 715 m); and Ankareh Formation (930 ft or 283 m), all of Triassic age; the Nugget Sandstone (1610 ft or 491 m), Twin Creek Limestone, Preuss Sandstone, and Stump Formation, all of Jurassic age; and the Salt Lake formation and the Sublette conglomerate, both Pliocene postorogenic continental deposits. Generally these formations are thinner than in nearby areas to the west and northwest. Raymond Canyon lies on the upper plate of the Tunp thrust and the lower plate of the Crawford thrust of the Idaho-Wyoming thrust belt. Thus, it lies near the middle of the imbricate stack of shallowly dipping thrust faults that formed in the late Mesozoic. Study of the stratigraphy, structure, petrography, and inferred depositional environments exposed in Raymond Canyon may be helpful to those engaged in energy development in the Idaho-Wyoming thrust belt.« less

Land-cover mapping of Red Rock Canyon National Conservation Area and Coyote Springs, Piute-Eldorado Valley, and Mormon Mesa Areas of Critical Environmental Concern, Clark County, Nevada

USGS Publications Warehouse

Smith, J. LaRue; Damar, Nancy A.; Charlet, David A.; Westenburg, Craig L.

2014-01-01

DigitalGlobe’s QuickBird satellite high-resolution multispectral imagery was classified by using Visual Learning Systems’ Feature Analyst feature extraction software to produce land-cover data sets for the Red Rock Canyon National Conservation Area and the Coyote Springs, Piute-Eldorado Valley, and Mormon Mesa Areas of Critical Environmental Concern in Clark County, Nevada. Over 1,000 vegetation field samples were collected at the stand level. The field samples were classified to the National Vegetation Classification Standard, Version 2 hierarchy at the alliance level and above. Feature extraction models were developed for vegetation on the basis of the spectral and spatial characteristics of selected field samples by using the Feature Analyst hierarchical learning process. Individual model results were merged to create one data set for the Red Rock Canyon National Conservation Area and one for each of the Areas of Critical Environmental Concern. Field sample points and photographs were used to validate and update the data set after model results were merged. Non-vegetation data layers, such as roads and disturbed areas, were delineated from the imagery and added to the final data sets. The resulting land-cover data sets are significantly more detailed than previously were available, both in resolution and in vegetation classes.

76 FR 14745 - Notice To Rescind a Notice of Intent To Prepare an Environmental Impact Statement, Ada and Canyon...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-17

... Agency meetings were held on November 8, 2007 and December 11, 2008. Environmental scans and screening... To Prepare an Environmental Impact Statement, Ada and Canyon Counties, ID AGENCY: Federal Highway Administration. ACTION: Rescind Notice of Intent to prepare an Environmental Impact Statement. SUMMARY: The FHWA...

77 FR 42505 - Notice of Intent To Prepare an Environmental Impact Statement for the Proposed Long Canyon Mine...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-19

... DEPARTMENT OF THE INTERIOR Bureau of Land Management [LLNVE03000 L51100000.GN0000. LVEMF1201550... Statement for the Proposed Long Canyon Mine Project, Elko County, NV AGENCY: Bureau of Land Management... 1969 (NEPA), as amended, and the Federal Land Policy and Management Act (FLPMA) of 1976, as amended...

Uranium occurrences in the Golden Gate Canyon and Ralston Creek areas, Jefferson County, Colorado

USGS Publications Warehouse

Adams, John Wagstaff; Gude, A.J.; Beroni, E.P.

1953-01-01

Pitchblende, associated with base-metal sulfides, has been found at nine localities in the northern part of Jefferson County, Colo., in shear zones that cut pre-Cambrian metamorphic and igneous rocks, chiefly hornblende gneiss, biotite schist, and granite pegmatite. The known deposits are in the vicinity of Halston Creek and Golden Gate Canyon, in the foothills of the Colorado Front Range and about 15 miles east of the pitchblende-producing area of the Central City district. Two of the pitchblende occurrences were found by a local prospector in 1949; the seven other deposits were found by Geological Survey. personnel in 1951-52. The pitchblende deposits, with one exception, are in major shear zones that contain veinlike bodies of carbonate-rich breccia that ranges from 1 to 5 feet in thickness. The breccias probably are related to the Laramide faults, or 'breccia reefs' of similar trend, mapped by Loverinq and Goddard (1950). The breccias are composed of fragments of bleached and iron-stained wall rock, usually hornblende gneiss, that have been cut by veins and cemented by carbonate minerals, quartz, and orthoclase(?). Pitchblende and associated ore minerals, chiefly copper sulfides, occur in and along the margins of the breccias and apparently were introduced at a late stage of the carbonate deposition. At one deposit, the Buckman, the pitchblende is in narrow shear zones not closely related to any large breccia bodies. Secondary uranium minerals are subordinate except at the Schwartzwalder mine, where torbernite and metatorbernite are common. Some alteration of pitchblende to non-opaque materials, believed to be hydrated oxides, has been noted in ore from two of the deposits.

Geomorphic process fingerprints in submarine canyons

USGS Publications Warehouse

Brothers, Daniel S.; ten Brink, Uri S.; Andrews, Brian D.; Chaytor, Jason D.; Twichell, David C.

2013-01-01

Submarine canyons are common features of continental margins worldwide. They are conduits that funnel vast quantities of sediment from the continents to the deep sea. Though it is known that submarine canyons form primarily from erosion induced by submarine sediment flows, we currently lack quantitative, empirically based expressions that describe the morphology of submarine canyon networks. Multibeam bathymetry data along the entire passive US Atlantic margin (USAM) and along the active central California margin near Monterey Bay provide an opportunity to examine the fine-scale morphology of 171 slope-sourced canyons. Log–log regression analyses of canyon thalweg gradient (S) versus up-canyon catchment area (A) are used to examine linkages between morphological domains and the generation and evolution of submarine sediment flows. For example, canyon reaches of the upper continental slope are characterized by steep, linear and/or convex longitudinal profiles, whereas reaches farther down canyon have distinctly concave longitudinal profiles. The transition between these geomorphic domains is inferred to represent the downslope transformation of debris flows into erosive, canyon-flushing turbidity flows. Over geologic timescales this process appears to leave behind a predictable geomorphic fingerprint that is dependent on the catchment area of the canyon head. Catchment area, in turn, may be a proxy for the volume of sediment released during geomorphically significant failures along the upper continental slope. Focused studies of slope-sourced submarine canyons may provide new insights into the relationships between fine-scale canyon morphology and down-canyon changes in sediment flow dynamics.

Geologic map of the Glen Canyon Dam 30’ x 60’ quadrangle, Coconino County, northern Arizona

USGS Publications Warehouse

Billingsley, George H.; Priest, Susan S.

2013-01-01

The Glen Canyon Dam 30’ x 60’ quadrangle is characterized by nearly flat lying to gently dipping Paleozoic and Mesozoic sedimentary strata that overlie tilted Proterozoic strata or metasedimentary and igneous rocks similar to those exposed at the bottom of Grand Canyon southwest of the quadrangle. Mississippian to Permian rocks are exposed in the walls of Marble Canyon; Permian strata and minor outcrops of Triassic strata form the surface bedrock of House Rock Valley and Marble Plateau, southwestern quarter of the quadrangle. The Paleozoic strata exposed in Marble Canyon and Grand Canyon south of the map are likely present in the subsurface of the entire quadrangle but with unknown facies and thickness changes. The Mesozoic sedimentary rocks exposed along the Vermilion and Echo Cliffs once covered the entire quadrangle, but Cenozoic erosion has removed most of these rocks from House Rock Valley and Marble Plateau areas. Mesozoic strata remain over much of the northern and eastern portions of the quadrangle where resistant Jurassic sandstone units form prominent cliffs, escarpments, mesas, buttes, and much of the surface bedrock of the Paria, Kaibito, and Rainbow Plateaus. Jurassic rocks in the northeastern part of quadrangle are cut by a sub-Cretaceous regional unconformity that bevels the Entrada Sandstone and Morrison Formation from Cummings Mesa southward to White Mesa near Kaibito. Quaternary deposits, mainly eolian, mantle much of the Paria, Kaibito, and Rainbow Plateaus in the northern and northeastern portion of the quadrangle. Alluvial deposits are widely distributed over parts of House Rock Valley and Marble Plateau in the southwest quarter of the quadrangle. The east-dipping strata of the Echo Cliffs Monocline forms a general north-south structural boundary through the central part of the quadrangle, separating Marble and Paria Plateaus west of the monocline from the Kaibito Plateau east of the monocline. The Echo Cliffs Monocline continues north of

Analysis of In-Canyon Flow Characterisitcs in step-up street canyons

NASA Astrophysics Data System (ADS)

PARK, S.; Kim, J.; Choi, W.; Pardyjak, E.

2017-12-01

Flow characteristics in strep-up street canyons were investigated focusing on in-canyon region. To see the effects of the building geometry, two building height ratios [ratio of the upwind (Hu) to downwind building heights (Hd) = 0.33, 0.6] were considered and eight building length ratios [ratio of the cross-wind building length (L) to street-canyon width (S) from 0.5 to 4 with the increment of 0.5] were systematically changed. For the model validation, the simulated results were compared with the wind- tunnel data measured for Hu/Hd = 0.33, 0.6 and L/S = 1, 2, 3, and 4. In the CFD model simulations, the corner vortices at the downwind side near the ground level and the recirculation zones above the downwind buildings had the relatively small extents, compared with those in the wind-tunnel experiments. However, the CFD model reproduced the main flow features such as the street-canyon vortices, circulations above the building roof, and the positions of the stagnation points on the downwind building walls in the wind-tunnel experiments reasonably well. By further analyzing the three-dimensional flow structures based on the numerical results simulated in the step-up street canyons, we schematically suggested the flow characteristics with different building-height and building-length ratios.

Carbon transport in Monterey Submarine Canyon

NASA Astrophysics Data System (ADS)

Barry, J.; Paull, C. K.; Xu, J. P.; Clare, M. A.; Gales, J. A.; Buck, K. R.; Lovera, C.; Gwiazda, R.; Maier, K. L.; McGann, M.; Parsons, D. R.; Simmons, S.; Rosenberger, K. J.; Talling, P. J.

2017-12-01

Submarine canyons are important conduits for sediment transport from continental margins to the abyss, but the rate, volume, and time scales of material transport have been measured only rarely. Using moorings with current meters, sediment traps (10 m above bottom) and optical backscatter sensors, we measured near-bottom currents, suspended sediment concentrations, and sediment properties at 1300 m depth in Monterey Canyon and at a non-canyon location on the continental slope at the same depth. Flow and water column backscatter were used to characterize "ambient" conditions when tidal currents dominated the flow field, and occasional "sediment transport events" when anomalously high down-canyon flow with sediment-laden waters arrived at the canyon mooring. The ambient sediment flux measured in sediment traps in Monterey Canyon was 350 times greater than measured at the non-canyon location. Although the organic carbon content of the canyon sediment flux during ambient periods was low (1.8 %C) compared to the slope location (4.9 %C), the ambient carbon transport in the canyon was 130 times greater than at the non-canyon site. Material fluxes during sediment transport events were difficult to measure owing to clogging of sediment traps, but minimal estimates indicate that mass transport during events exceeds ambient sediment fluxes through the canyon by nearly 3 orders of magnitude, while carbon transport is 380 times greater. Estimates of the instantaneous and cumulative flux of sediment and carbon from currents, backscatter, and sediment properties indicated that: 1) net flux is down-canyon, 2) flux is dominated by sediment transport events, and 3) organic carbon flux through 1300 m in Monterey Canyon was ca. 1500 MT C per year. The injection of 1500 MTCy-1 into the deep-sea represents ca. 260 km2 of the sediment C flux measured at the continental slope station (5.8 gCm-2y-1) and is sufficient to support a benthic community carbon demand of 5 gCm-2y-1 over 300 km2.

Strategic guidelines for street canyon geometry to achieve sustainable street air quality—part II: multiple canopies and canyons

NASA Astrophysics Data System (ADS)

Chan, Andy T.; Au, William T. W.; So, Ellen S. P.

The flow field and pollutant dispersion characteristics in a three-dimensional urban street canyon are investigated for various building array geometries. The street canyon in consideration is located in a multi-canopy building array that is similar to realistic estate situations. The pollutant dispersion characteristics are studied for various canopy aspect ratios, namely: the canyon height to width ratio, canyon length to height ratio, canyon breadth ratio and crossroad locations are studied. A three-dimensional field-size canyon has been analysed through numerical simulations using k- ɛ turbulence model. As expected, the wind flow and mode of pollutant dispersion is strongly dependent on the various flow geometric configurations and that the results can be different from that of a single canyon system. For example, it is found that the pollutant retention value is minimum when the canyon height-to-width ratio is approximately 0.8, or that the building height ratio is 0.5. Various rules of thumbs on urban canyon geometry have been established for good pollutant dispersion.

Ecological Functioning in Two Mid-Atlantic Bight Submarine Canyons: Macrofauna Community Trends and the Role of Canyon Specific Processes

NASA Astrophysics Data System (ADS)

Robertson, C.; Bourque, J. R.; Davies, A. J.; Duineveld, G.; Mienis, F.; Brooke, S.; Ross, S. W.; Demopoulos, A. W.

2016-02-01

Submarine canyons are complex systems, acting as major conduits of organic matter along continental shelves and promoting gradients in food resources, turbidity flows, habitat heterogeneity, and areas of sediment resuspension and deposition. In the western North Atlantic, a large multidisciplinary program was conducted in two major Mid-Atlantic Bight (MAB) canyons (Baltimore and Norfolk canyons). This Atlantic Deepwater Canyons project was funded by BOEM, NOAA, and USGS. Here we investigate the `canyon effect' on benthic ecosystem ecology and functioning of two canyon systems by defining canyon specific processes influencing MAB shelf benthic community trends. Sediment cores were collected in 2012 and 2013 with a NIOZ box corer along the main axes ( 180-1200m) of Baltimore and Norfolk Canyon and at comparable depths on the adjacent continental slope. Whole community macrofaunal (>300 μm) abundance and biomass data provided insight into community trends across depth and biogeochemical gradients by coupling diversity metrics and biological trait analyses with sediment biogeochemistry and hydrodynamic data. The canyons exhibited clear differences in sediment profiles, hydrodynamic regimes and enrichment depocenters as well as significantly distinct infauna communities. Interestingly, both canyons showed bimodal distributions in abundances and diversity of infauna and a shallowing of species maxima which was not present on adjacent slopes. We hypothesize that physical canyon processes are important regulators in the depth of observed species maxima and community functioning on the MAB shelf, on local and regional scales. Unique sediment dynamics, organic enrichment, and hydrographic conditions were significant factors in structuring benthic community differences in MAB canyons The study provides a complete benthic infaunal appraisal of two canyon systems in the western Atlantic, incorporating biogeochemistry and oceanography to increase our understanding of canyon

Formative flow in bedrock canyons

NASA Astrophysics Data System (ADS)

Venditti, J. G.; Kwoll, E.; Rennie, C. D.; Church, M. A.

2017-12-01

In alluvial channels, it is widely accepted that river channel configuration is set by a formative flow that represents a balance between the magnitude and frequency of flood flows. The formative flow is often considered to be one that is just capable of filling a river channel to the top of its banks. Flows much above this formative flow are thought to cause substantial sediment transport and rearrange the channel morphology to accommodate the larger flow. This idea has recently been extended to semi-alluvial channels where it has been shown that even with bedrock exposed, the flows rarely exceed that required to entrain the local sediment cover. What constitutes a formative flow in a bedrock canyon is not clear. By definition, canyons have rock walls and are typically incised vertically, removing the possibility of the walls being overtopped, as can occur in an alluvial channel at high flows. Canyons are laterally constrained, have deep scour pools and often have width to maximum depth ratios approaching 1, an order of magnitude lower than alluvial channels. In many canyons, there are a sequence of irregularly spaced scour pools. The bed may have intermittent or seasonal sediment cover, but during flood flows the sediment bed is entrained leaving a bare bedrock channel. It has been suggested that canyons cut into weak, well-jointed rock may adjust their morphology to the threshold for block plucking because the rock bed is labile during exceptionally large magnitude flows. However, this hypothesis does not apply to canyons cut into massive crystalline rock where abrasion is the dominant erosion process. Here, we argue that bedrock canyon morphology is adjusted to a characteristic flow structure developed in bedrock canyons. We show that the deeply scoured canyon floor is adjusted to a velocity inversion that is present at low flows, but gets stronger at high flows. The effect is to increase boundary shear stresses along the scour pool that forms in constricted

Let's Bet on Sediments! Hudson Canyon Cruise--Grades 9-12. Focus: Sediments of Hudson Canyon.

ERIC Educational Resources Information Center

National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

These activities are designed to teach about the sediments of Hudson Canyon. Students investigate and analyze the patterns of sedimentation in the Hudson Canyon, observe how heavier particles sink faster than finer particles, and learn that submarine landslides are avalanches of sediment in deep ocean canyons. The activity provides learning…

Grand Canyon Monitoring and Research Center

USGS Publications Warehouse

Hamill, John F.

2009-01-01

The Grand Canyon of the Colorado River, one of the world's most spectacular gorges, is a premier U.S. National Park and a World Heritage Site. The canyon supports a diverse array of distinctive plants and animals and contains cultural resources significant to the region's Native Americans. About 15 miles upstream of Grand Canyon National Park sits Glen Canyon Dam, completed in 1963, which created Lake Powell. The dam provides hydroelectric power for 200 wholesale customers in six western States, but it has also altered the Colorado River's flow, temperature, and sediment-carrying capacity. Over time this has resulted in beach erosion, invasion and expansion of nonnative species, and losses of native fish. Public concern about the effects of Glen Canyon Dam operations prompted the passage of the Grand Canyon Protection Act of 1992, which directs the Secretary of the Interior to operate the dam 'to protect, mitigate adverse impacts to, and improve values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established...' This legislation also required the creation of a long-term monitoring and research program to provide information that could inform decisions related to dam operations and protection of downstream resources.

Wintertime Boundary Layer Structure in the Grand Canyon.

NASA Astrophysics Data System (ADS)

Whiteman, C. David; Zhong, Shiyuan; Bian, Xindi

1999-08-01

Wintertime temperature profiles in the Grand Canyon exhibit a neutral to isothermal stratification during both daytime and nighttime, with only rare instances of actual temperature inversions. The canyon warms during daytime and cools during nighttime more or less uniformly through the canyon's entire depth. This weak stability and temperature structure evolution differ from other Rocky Mountain valleys, which develop strong nocturnal inversions and exhibit convective and stable boundary layers that grow upward from the valley floor. Mechanisms that may be responsible for the different behavior of the Grand Canyon are discussed, including the possibility that the canyon atmosphere is frequently mixed to near-neutral stratification when cold air drains into the top of the canyon from the nearby snow-covered Kaibab Plateau. Another feature of canyon temperature profiles is the sharp inversions that often form near the canyon rims. These are generally produced when warm air is advected over the canyon in advance of passing synoptic-scale ridges.Wintertime winds in the main canyon are not classical diurnal along-valley wind systems. Rather, they are driven along the canyon axis by the horizontal synoptic-scale pressure gradient that is superimposed along the canyon's axis by passing synoptic-scale weather disturbances. They may thus bring winds into the canyon from either end at any time of day.The implications of the observed canyon boundary layer structure for air pollution dispersion are discussed.

78 FR 48670 - Boulder Canyon Project

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-09

... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Canyon Project (BCP) electric service provided by the Western Area Power Administration (Western). The... States Department of Energy, Western Area Power Administration, Boulder Canyon Project, 133 FERC ] 62,229...

Street canyon aerosol pollutant transport measurements.

PubMed

Longley, I D; Gallagher, M W; Dorsey, J R; Flynn, M; Bower, K N; Allan, J D

2004-12-01

Current understanding of dispersion in street canyons is largely derived from relatively simple dispersion models. Such models are increasingly used in planning and regulation capacities but are based upon a limited understanding of the transport of substances within a real canyon. In recent years, some efforts have been made to numerically model localised flow in idealised canyons (e.g., J. Appl. Meteorol. 38 (1999) 1576-89) and stepped canyons (Assimakopoulos V. Numerical modelling of dispersion of atmospheric pollution in and above urban canopies. PhD thesis, Imperial College, London, 2001) but field studies in real canyons are rare. To further such an understanding, a measurement campaign has been conducted in an asymmetric street canyon with busy one-way traffic in central Manchester in northern England. The eddy correlation method was used to determine fluxes of size-segregated accumulation mode aerosol. Measurements of aerosol at a static location were made concurrently with measurements on a platform lift giving vertical profiles. Size-segregated measurements of ultrafine and coarse particle concentrations were also made simultaneously at various heights. In addition, a small mobile system was used to make measurements of turbulence at various pavement locations within the canyon. From this data, various features of turbulent transport and dispersion in the canyon will be presented. The concentration and the ventilation fluxes of vehicle-related aerosol pollutants from the canyon will be related to controlling factors. The results will also be compared with citywide ventilation data from a separate measurement campaign conducted above the urban canopy.

77 FR 48151 - Boulder Canyon Project

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-13

... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Canyon Project (BCP) electric service provided by the Western Area Power Administration (Western). The... INFORMATION: Hoover Dam, authorized by the Boulder Canyon Project Act (45 Stat. 1057, December 21, 1928), sits...

Durable terrestrial bedrock predicts submarine canyon formation

USGS Publications Warehouse

Smith, Elliot; Finnegan, Noah J.; Mueller, Erich R.; Best, Rebecca J.

2017-01-01

Though submarine canyons are first-order topographic features of Earth, the processes responsible for their occurrence remain poorly understood. Potentially analogous studies of terrestrial rivers show that the flux and caliber of transported bedload are significant controls on bedrock incision. Here we hypothesize that coarse sediment load could exert a similar role in the formation of submarine canyons. We conducted a comprehensive empirical analysis of canyon occurrence along the West Coast of the contiguous United States which indicates that submarine canyon occurrence is best predicted by the occurrence of durable crystalline bedrock in adjacent terrestrial catchments. Canyon occurrence is also predicted by the flux of bed sediment to shore from terrestrial streams. Surprisingly, no significant correlation was observed between canyon occurrence and the slope or width of the continental shelf. These findings suggest that canyon incision is promoted by greater yields of durable terrestrial clasts to the shore.

Morphology, distribution, and development of submarine canyons on the United States Atlantic continental slope between Hudson arid Baltimore Canyons

NASA Astrophysics Data System (ADS)

Twichell, David C.; Roberts, David G.

1982-08-01

The distribution and morphology of submarine canyons off the eastern United States between Hudson and Baltimore Canyons have been mapped by long-range sidescan sonar. In this area canyons are numerous, and their spacing correlates with overall slope gradient; they are absent where the gradient is less than 3°, are 2 to 10 km apart where the gradient is 3° to 5°, and are 1.5 to 4 km apart where the gradient exceeds 6°. Canyons range from straight to sinuous; those having sinuous axes indent the edge of the continental shelf and appear to be older than those that head on the upper slope and have straighter axes. A difference in canyon age would suggest that canyons are initiated on the continental slope and only with greater age erode headward to indent the shelf. Shallow gullies on the middle and upper slope parts of the canyon walls suggest that submarine erosion has been a major process in a recent phase of canyon development. *Present address: British Petroleum, Moorgate, London EC2Y 9BU, England

Research Furthers Conservation of Grand Canyon Sandbars

USGS Publications Warehouse

Melis, Theodore S.; Topping, David J.; Rubin, David M.; Wright, Scott A.

2007-01-01

Grand Canyon National Park lies approximately 25 km (15 mi) down-river from Glen Canyon Dam, which was built on the Colorado River just south of the Arizona-Utah border in Glen Canyon National Recreation Area. Before the dam began to regulate the Colorado River in 1963, the river carried such large quantities of red sediment, for which the Southwest is famous, that the Spanish named the river the Rio Colorado, or 'red river'. Today, the Colorado River usually runs clear below Glen Canyon Dam because the dam nearly eliminates the main-channel sand supply. The daily and seasonal flows of the river were also altered by the dam. These changes have disrupted the sedimentary processes that create and maintain Grand Canyon sandbars. Throughout Grand Canyon, sandbars create habitat for native plants and animals, supply camping beaches for river runners and hikers, and provide sediment needed to protect archaeological resources from weathering and erosion. Maintenance of sandbars in the Colorado River ecosystem, the river corridor that stretches from the dam to the western boundary of Grand Canyon National Park, is a goal of the Glen Canyon Dam Adaptive Management Program. The program is a federally authorized initiative to ensure that the mandates of the Grand Canyon Protection Act of 1992 are met through advances in information and resource management. The U.S. Geological Survey's Grand Canyon Monitoring and Research Center has responsibility for scientific monitoring and research efforts for the program. Extensive research and monitoring during the past decade have resulted in the identification of possible alternatives for operating Glen Canyon Dam that hold new potential for the conservation of sand resources.

Mars Canyon with Los Angeles for Scale

NASA Image and Video Library

2006-03-13

A Grand Canyon of Mars slices across the Red Planet near its equator. This canyon -- Valles Marineris, or the Mariner Valley -- is 10 times longer and deeper than Arizona Grand Canyon, and 20 times wider

Time-domain electromagnetic signatures of polymetallic vein deposits in Cottonwood Canyon area, Santa Cruz County, Arizona

USGS Publications Warehouse

Bultman, Mark W.

2002-01-01

This report tests the usefulness of airborne time-domain electromagnetic (TEM) data on three mineral-resource-related issues: (1) to test whether known mineral deposits at or near the surface display any signal in the TEM data; 2) determine whether TEM data can be used to locate bedrock concealed by basin fill; and (3) if the exposed mineral deposits display a signal in the TEM data, to determine if whether deposits are recognizable at depth in outcropping bedrock or in bedrock concealed beneath basin fill. Because Earth's total-intensity magnetic field data are also acquired with the TEM data, these data are included in the analysis. The Cottonwood Canyon area in Santa Cruz County, Arizona, contains several polymetallic vein deposits, including those of the Tyndall, Salero, and Wrightson mining districts, all of which have had significant mineral production. Polymetallic vein deposits, which generally consist of veins of disseminated metallic minerals, commonly exhibit a response to electrical geophysical methods. Also, on the basis of other studies, the conditions that produced the polymetallic vein mineralization in the region are believed to extend offshore into the bedrock concealed by basin fill. The polymetallic vein deposits of the Cottonwood Canyon area all display a geophysical signature in the TEM data. These deposits occur in bedrock that has, in general, a very low resistivity. The polymetallic vein deposits are associated with high-conductivity regions that extend from deep in the bedrock to the surface. These high-conductivity regions can be quite narrow (100 m) or quite wide (1 km); most are relatively narrow. Every known mineral deposit or prospect is associated with a high-conductivity feature. High-conductivity regions can also occur without an association with known mineral deposits. Airborne TEM data appear to be able to locate the basin fill/bedrock contact beneath basin fill. The basin fill (both dry and saturated) is generally more

Environmental assessment: Davis Canyon site, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOEmore » prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has fond that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization. 181 figs., 175 tabs.« less

Environmental assessment: Davis Canyon site, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high- level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, themore » DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of the five sites suitable for characterization.« less

Environmental assessment: Davis Canyon site, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOEmore » prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considering for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization.« less

Plant diversity at Box-Death Hollow Wilderness Area, Garfield County, Utah

Treesearch

Wendy Rosler; Janet G. Cooper; Renee Van Buren; Kimball T. Harper

2001-01-01

"The Box" is a canyon located in the western portion of Box-Death Hollow Wilderness Area, Garfield County, southern Utah. The objectives of this study included: (1) collect, identify and make a checklist of the species of vascular plants found in "The Box," (2) search for threatened and endangered species within the area, (3) provide an opportunity...

Hanging canyons of Haida Gwaii, British Columbia, Canada: Fault-control on submarine canyon geomorphology along active continental margins

NASA Astrophysics Data System (ADS)

Harris, Peter T.; Barrie, J. Vaughn; Conway, Kim W.; Greene, H. Gary

2014-06-01

Faulting commonly influences the geomorphology of submarine canyons that occur on active continental margins. Here, we examine the geomorphology of canyons located on the continental margin off Haida Gwaii, British Columbia, that are truncated on the mid-slope (1200-1400 m water depth) by the Queen Charlotte Fault Zone (QCFZ). The QCFZ is an oblique strike-slip fault zone that has rates of lateral motion of around 50-60 mm/yr and a small convergent component equal to about 3 mm/yr. Slow subduction along the Cascadia Subduction Zone has accreted a prism of marine sediment against the lower slope (1500-3500 m water depth), forming the Queen Charlotte Terrace, which blocks the mouths of submarine canyons formed on the upper slope (200-1400 m water depth). Consequently, canyons along this margin are short (4-8 km in length), closely spaced (around 800 m), and terminate uniformly along the 1400 m isobath, coinciding with the primary fault trend of the QCFZ. Vertical displacement along the fault has resulted in hanging canyons occurring locally. The Haida Gwaii canyons are compared and contrasted with the Sur Canyon system, located to the south of Monterey Bay, California, on a transform margin, which is not blocked by any accretionary prism, and where canyons thus extend to 4000 m depth, across the full breadth of the slope.

Anomalous concentrations of gold, silver, and other metals in the Mill Canyon area, Cortez quadrangle, Eureka and Lander Counties, Nevada

USGS Publications Warehouse

Elliott, James E.; Wells, John David

1968-01-01

The Mill Canyon area is in the eastern part of the Cortez window of the Roberts Mountains thrust belt in the Cortez quadrangle, north-central Nevada. Gold and silver ores have been mined from fissure veins in Jurassic quartz monzonite and in the bordering Wenban Limestone of Devonian age. Geochemical data show anomalies of gold, silver, lead, zinc, copper, arsenic, antimony, mercury, and tellurium. Geologic and geochemical studies indicate that a formation favorable for gold deposition, the Roberts Mountains Limestone of Silurian age, may be found at depth near the mouth of Mill Canyon.

Ox Mountain Sanitary Landfill Apanolio Canyon Expansion Site, San Mateo County, California. Volume 2. Appendix

DTIC Science & Technology

1989-04-01

old-growth forest located between Sonoma County and the Oregon border. The exact northern limit of the small southern I population is not known...meadow habitat on the inland side of sand dunes at Pt. Reyes (Matin County) and Bodega Bay ( Sonoma County ). Historically, the silverspot also probably...and Sonoma County (6.5 mi. northeast of Penngrove). Collection dates ranged from 27IJanuary to 30 July. Most of the species of Hydrochara are similar

Submarine sand dunes and sedimentary environments in Oceanographer Canyon.

USGS Publications Warehouse

Valentine, P.C.; Cooper, R.A.; Uzmann, J.R.

1984-01-01

Observations from research submersibles in the northern part of Oceanographer Canyon reveal the presence of an extensive field of large sand dunes on the canyon floor. The dunes are medium to coarse sand, are oriented across the axis, and the largest of them are as high as 3 m and have wavelengths up to 15 m. Their asymmetry, grain size, and height suggest that they are formed by axial currents flowing up- and downcanyon and that the largest dunes require flows of at least 70 cm/sec. Shelf sand, low in silt and clay content, is transported by currents down and along the canyon walls onto the canyon floor. As the sand enters the canyon, it is mixed with immobile gravel deposits on the canyon rim; lower on the walls, the sand is mixed with silt and clay burrowed by organisms from the semiconsolidated sandy silt that underlies the canyon walls and floor. Upon reaching the canyon floor, the sand is sculpted into bed forms by currents, and the fines are winnowed out and transported out of the canyon. At present, the shelf and canyon walls are being eroded by bottom currents and burrowing organisms, whereas the canyon floor is covered by mobile sand that moves both up and down the axis in this part of the canyon.

The Black Canyon of the Gunnison: Today and Yesterday

USGS Publications Warehouse

Hansen, Wallace R.

1965-01-01

Since the early visit of Captain John William Gunnison in the middle of the last century, the Black Canyon of the Gunnison has stirred mixed apprehension and wonder in the hearts of its viewers. It ranks high among the more awesome gorges of North America. Many great western canyons are as well remembered for their brightly colored walls as for their airy depths. Not so the Black Canyon. Though it is assuredly not black, the dark-gray tones of its walls and the hazy shadows of its gloomy depths join together to make its name well deserved. Its name conveys an impression, not a picture. After the first emotional impact of the canyon, the same questions come to the minds of most reflective viewers and in about the following order: How deep is the Black Canyon, how wide, how does it compare with other canyons, what are the rocks, how did it form, and how long did it take? Several western canyons exceed the Black Canyon in overall size. Some are longer; some are deeper; some are narrower; and a few have walls as steep. But no other canyon in North American combines the depth, narrowness, sheerness, and somber countenance of the Black Canyon. In many places the Black Canyon is as deep as it is wide. Between The Narrows and Chasm View in the Black Canyon of the Gunnison National Monument (fig. 15) it is much deeper than wide. Average depth in the monument is about 2,000 feet, ranging from a maximum of about 2,700 feet, north of Warner Point (which also is the greatest depth anywhere in the canyon), to a minimum of about 1,750 feet at The Narrows. The stretch of canyon between Pulpit Rock and Chasm View, including The Narrows, though the shallowest in the monument, is also the narrowest, has some of the steepest walls, and is, therefore, among the most impressive segments of the canyon (fig. 3). Profiles of several well-known western canyons are shown in figure 1. Deepest of these by far is Hells Canyon of the Snake, on the Idaho-Oregon border. Clearly, it dwarfs the

The Morpho-Acoustic Structure of Sakarya Canyon, Southwestern Black Sea

NASA Astrophysics Data System (ADS)

Nasıf, Aslıhan; Dondurur, Derman

2017-04-01

In this study, Black Sea outlet of Sakarya River in the western Black Sea continental margin is analyzed using a total of 1400 km multichannel seismics, Chirp sub-bottom profiler and multibeam bathymetric datasets. Three scientific cruises between 2012 and 2016 have been conducted in the area to map and reveal the morphological structure of the Sakarya Canyon along the southwestern Black Sea margin. The Western Black Sea Turkey coastal area is also home to many active canyons. These canyons extend from deep shallow shelf areas of about 100 m to deep water depths of 1800-2000 m. The largest and most active of the Western Black Sea canyons is the Sakarya Canyon, which is located at the exit of the Sakarya River. Research on submarine canyons are important for military submarine operations, positioning of marine engineering structures and understanding the sedimentology, ecological and oceanographic functions of canyons. The canyon systems observed on continental slopes lead to the most convenient sedimentary transportation from the shelf platform. The dataset from study area was analyzed to identify the acoustic structure of Sakarya Canyon, the morphology of which is not widely known. Bathymetric data shows that the canyon consists of two separate canyon heads in the shallow continental shelf to the south, both of which coalesce at 867 m water depth. This meandering canyon then deepens along the continental slope towards to north. Another wide canyon from west, named as Kefken Canyon, then conjoins this main canyon at approximately 1000 m water depths to form the deeper structure of the modern Sakarya Canyon. In the distal parts, canyon gets wider and wider, and its thalweg becomes significantly flat eroded by the present day activity of small scale turbidity channels. Multichannel seismic data indicate that the Sakarya Canyon was formed by the activity of hyperphycnal flows and also clearly show the extensive sediment erosion along the canyon.

The State of the Colorado River Ecosystem in Grand Canyon: A Report of the Grand Canyon Monitoring and Research Center 1991-2004

USGS Publications Warehouse

Gloss, Steven P.; Lovich, Jeffrey E.; Melis, Theodore S.

2005-01-01

This report is an important milestone in the effort by the Secretary of the Interior to implement the Grand Canyon Protection Act of 1992 (GCPA; title XVIII, secs. 1801-1809, of Public Law 102-575), the most recent authorizing legislation for Federal efforts to protect resources downstream from Glen Canyon Dam. The chapters that follow are intended to provide decision makers and the American public with relevant scientific information about the status and recent trends of the natural, cultural, and recreational resources of those portions of Grand Canyon National Park and Glen Canyon National Recreation Area affected by Glen Canyon Dam operations. Glen Canyon Dam is one of the last major dams that was built on the Colorado River and is located just south of the Arizona-Utah border in the lower reaches of Glen Canyon National Recreation Area, approximately 15 mi (24 km) upriver from Grand Canyon National Park (fig. 1). The information presented here is a product of the Glen Canyon Dam Adaptive Management Program (GCDAMP), a federally authorized initiative to ensure that the primary mandate of the GCPA is met through advances in information and resource management. The U.S. Geological Survey`s (USGS) Grand Canyon Monitoring and Research Center (GCMRC) has responsibility for the scientific monitoring and research efforts for the program, including the preparation of reports such as this one.

77 FR 67391 - Notice of Proposed Supplementary Rules on Public Land in Water Canyon, Humboldt County, NV

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-09

... speed limit is proposed because there have been numerous accidents along the main access/canyon road in Zone 1. These accidents have primarily been a result of excess speed due to no posted or enforceable..., or irritant gas device. Motor vehicle includes, but is not limited to, automobiles, motorcycles, all...

Ventilation Processes in a Three-Dimensional Street Canyon

NASA Astrophysics Data System (ADS)

Nosek, Štěpán; Kukačka, Libor; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

2016-05-01

The ventilation processes in three different street canyons of variable roof geometry were investigated in a wind tunnel using a ground-level line source. All three street canyons were part of an urban-type array formed by courtyard-type buildings with pitched roofs. A constant roof height was used in the first case, while a variable roof height along the leeward or windward walls was simulated in the two other cases. All street-canyon models were exposed to a neutrally stratified flow with two approaching wind directions, perpendicular and oblique. The complexity of the flow and dispersion within the canyons of variable roof height was demonstrated for both wind directions. The relative pollutant removals and spatially-averaged concentrations within the canyons revealed that the model with constant roof height has higher re-emissions than models with variable roof heights. The nomenclature for the ventilation processes according to quadrant analysis of the pollutant flux was introduced. The venting of polluted air (positive fluctuations of both concentration and velocity) from the canyon increased when the wind direction changed from perpendicular to oblique, irrespective of the studied canyon model. Strong correlations (>0.5) between coherent structures and ventilation processes were found at roof level, irrespective of the canyon model and wind direction. This supports the idea that sweep and ejection events of momentum bring clean air in and detrain the polluted air from the street canyon, respectively.

Geology and biology of Oceanographer submarine canyon.

USGS Publications Warehouse

Valentine, P.C.; Uzmann, J.R.; Cooper, R.A.

1980-01-01

Santonian beds more than 100 m thick are the oldest rocks collected from the canyon. Quaternary silty clay veneers the canyon walls in many places and is commonly burrowed by benthic organisms that cause extensive erosion of the canyon walls, especially in the depth zone (100-1300 m) inhabited by the crabs Geryon and Cancer. Bioerosion is minimal on high, near-vertical cliffs of sedimentary rock, in areas of continual sediment movement, and where the sea floor is paved by gravel. A thin layer of rippled, unconsolidated silt and sand is commonly present on the canyon walls and in the axis. Shelf sediments are transported from Georges Bank over the E rim and in the Canyon by the SW drift and storm currents; tidal currents and internal waves move the sediment downcanyon along the walls and axis.- from Authors

Discovery of two new large submarine canyons in the Bering Sea

USGS Publications Warehouse

Carlson, P.R.; Karl, Herman A.

1984-01-01

The Beringian continental margin is incised by some of the world's largest submarine canyons. Two newly discovered canyons, St. Matthew and Middle, are hereby added to the roster of Bering Sea canyons. Although these canyons are smaller and not cut back into the Bering shelf like the five very large canyons, they are nonetheless comparable in size to most of the canyons that have been cut into the U.S. eastern continental margin and much larger than the well-known southern California canyons. Both igneous and sedimentary rocks of Eocene to Pliocene age have been dredged from the walls of St. Matthew and Middle Canyons as well as from the walls of several of the other Beringian margin canyons, thus suggesting a late Tertiary to Quaternary genesis of the canyons. We speculate that the ancestral Yukon and possibly Anadyr Rivers were instrumental in initiating the canyon-cutting processes, but that, due to restrictions imposed by island and subsea bedrock barriers, cutting of the two newly discovered canyons may have begun later and been slower than for the other five canyons. ?? 1984.

Chapter 12. Canyons microbiology studies

USGS Publications Warehouse

Kellogg, Christina A.; Lawler, Stephanie N.

2017-01-01

Off the eastern coast of the United States, several deep canyons cut through the continental shelf, acting like funnels to move sediment from the shelf out to the deep seafloor. Exposed rock outcrops and ledges along the walls of these canyons provide important habitat for deepsea corals and sponges. Although a few scientific expeditions have visited these canyons in the 1970s (Hecker and Blechschmidt 1979, Hecker et al. 1980), their purpose was mainly to map the contours and capture photographs of the bottom using manned submersibles and towed cameras. Our knowledge of the biodiversity in these complex ecosystems is limited; we know little about the macrofauna (e.g., fishes, crabs, sponges, and deepsea corals) and even less about the microbiota.The research described in this report was conducted from 2011 to 2015 as part of the Bureau of Ocean Energy Management (BOEM) study, entitled “Atlantic Deepwater Canyons” study. This work used molecular and microbiological techniques to examine the microbial ecology and diversity associated with Baltimore and Norfolk canyons. Specifically, this work focused on the microbial ecology of four species of octocorals (Acanthogorgia aspera, Anthothela grandiflora, Paramuricea placomus, and Primnoa resedaeformis), the microbial diversity in sediments within and outside the canyons, and a settling plate experiment designed to characterize microbial biofilm formation on a variety of hard substrates.

36 CFR 7.19 - Canyon de Chelly National Monument.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Canyon de Chelly National... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.19 Canyon de Chelly National Monument. (a) Visitors are prohibited from entering the canyons of Canyon de Chelly National Monument unless...

36 CFR 7.19 - Canyon de Chelly National Monument.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Canyon de Chelly National... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.19 Canyon de Chelly National Monument. (a) Visitors are prohibited from entering the canyons of Canyon de Chelly National Monument unless...

2008 High-Flow Experiment at Glen Canyon Dam Benefits Colorado River Resources in Grand Canyon National Park

USGS Publications Warehouse

Melis, Theodore S.; Topping, David J.; Grams, Paul E.; Rubin, David M.; Wright, Scott A.; Draut, Amy E.; Hazel, Joseph E.; Ralston, Barbara E.; Kennedy, Theodore A.; Rosi-Marshall, Emma; Korman, Josh; Hilwig, Kara D.; Schmit, Lara M.

2010-01-01

On March 5, 2008, the Department of the Interior began a 60-hour high-flow experiment at Glen Canyon Dam, Arizona, to determine if water releases designed to mimic natural seasonal flooding could be used to improve downstream resources in Glen Canyon National Recreation Area and Grand Canyon National Park. U.S. Geological Survey (USGS) scientists and their cooperators undertook a wide range of physical and biological resource monitoring and research activities before, during, and after the release. Scientists sought to determine whether or not high flows could be used to rebuild Grand Canyon sandbars, create nearshore habitat for the endangered humpback chub, and benefit other resources such as archaeological sites, rainbow trout, aquatic food availability, and riverside vegetation. This fact sheet summarizes research completed by January 2010.

Morphodynamic Model of Submarine Canyon Incision by Sandblasting

NASA Astrophysics Data System (ADS)

Zhang, L.; Parker, G.; Izumi, N.; Cartigny, M.; Li, T.; Wang, G.

2017-12-01

Submarine canyons are carved by turbidity currents under the deep sea. As opposed to subaerial canyons, the relevant processes are not easy to observe directly. Turbidity currents are bottom-hugging sediment gravity flows of that can incise or deposit on the seafloor to create submarine canyons or fans. The triggers of turbidity currents can be storms, edge waves, internal waves, canyon wall sapping, delta failure, breaching and hyperpycnal flows. The formation and evolution mechanisms of submarine canyons are similar to those of subaerial canyons, but have substantial differences. For example, sandblasting, rather than wear due to colliding gravel clasts is more likely to be the mechanism of bedrock incision. Submarine canyons incise downward, and often develop meander bends and levees within the canyon, so defining "fairways". Here we propose a simple model for canyon incision. The starting point of our model is the Macro Roughness Saltation Abrasion Alluviation model of Zhang et al. [2015], designed for bedrock incision by gravel clasts in mixed bedrock-alluvial rivers. We adapt this formulation to consider sandblasting as a means of wear. We use a layer-averaged model for turbidity current dynamics. The current contains a mixture of mud, which helps drive the flow but which does not cause incision, and sand, which is the agent of incision. We show that the model can successfully model channel downcutting, and indeed illustrate the early formation of net incisional cyclic steps, i.e. upstream-migrating undulations on the bed associated with transcritical (in the Froude sense) flow. These steps can be expected to abet the process of incision.

75 FR 20806 - Notice of Intent To Grant Exclusive License

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-21

... Research Service, intends to grant to Basin Seed Company, LLC of Nampa, Idaho, an exclusive license to the... Seed Company, LLC of Nampa, Idaho has submitted a complete and sufficient application for a license...

78 FR 3027 - Notice of Temporary Closures of Public Lands in La Paz County, AZ

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-15

... (CRIT) Reservation, the closed area runs east along Shea Road, then east into Osborne Wash on the Parker-Swansea Road to the Central Arizona Project (CAP) Canal, then north on the west side of the CAP Canal, crossing the canal on the county-maintained road, running northeast into Mineral Wash Canyon, then...

Availability of Additional Water for Chiricahua National Monument, Cochise County, Arizona

USGS Publications Warehouse

Johnson, Phillip W.

1962-01-01

The Chiricahua National Monument is in the eastern part of Cochise County, Ariz. The monument is about 35 miles southeast of Wilicox in the north end of the Chiricahua Mountains which border Sulphur Springs Valley on the west. The area is drained by two intermittent washes, one in Bonita and the other in Rhyolite Canyons. Shake Spring is the present source of water for the monument. It ranges in rate of flow from 2 to 12 gpm (gallons per minute) and during dry periods It is not adequate to support the requirements of the monument. Ample water to meet the present and future needs of the Chiricahua National Monument is available from a combination of several sources - undeveloped springs or seeps, capture of runoff out of the canyons, and wells drilled in the alluvium.

76 FR 5398 - Notice of Temporary Closure of Selected Public Lands in La Paz County, AZ

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-31

...-maintained roads and highways located on public lands that are located within 2 miles of the designated... east along Shea Road, then east into Osborne Wash on the Parker-Swansea Road to the Central Arizona...-maintained road, running northeast into Mineral Wash Canyon, then southeast on the county-maintained road...

Surprise and opportunity for learning in Grand Canyon: the Glen Canyon Dam Adaptive Management Program

USGS Publications Warehouse

Melis, Theodore S.; Walters, Carl; Korman, Josh

2015-01-01

With a focus on resources of the Colorado River ecosystem below Glen Canyon Dam, the Glen Canyon Dam Adaptive Management Program has included a variety of experimental policy tests, ranging from manipulation of water releases from the dam to removal of non-native fish within Grand Canyon National Park. None of these field-scale experiments has yet produced unambiguous results in terms of management prescriptions. But there has been adaptive learning, mostly from unanticipated or surprising resource responses relative to predictions from ecosystem modeling. Surprise learning opportunities may often be viewed with dismay by some stakeholders who might not be clear about the purpose of science and modeling in adaptive management. However, the experimental results from the Glen Canyon Dam program actually represent scientific successes in terms of revealing new opportunities for developing better river management policies. A new long-term experimental management planning process for Glen Canyon Dam operations, started in 2011 by the U.S. Department of the Interior, provides an opportunity to refocus management objectives, identify and evaluate key uncertainties about the influence of dam releases, and refine monitoring for learning over the next several decades. Adaptive learning since 1995 is critical input to this long-term planning effort. Embracing uncertainty and surprise outcomes revealed by monitoring and ecosystem modeling will likely continue the advancement of resource objectives below the dam, and may also promote efficient learning in other complex programs.

Why SRS Matters - H Canyon

ScienceCinema

Hunt, Paul; Lewczyk, Mike; Swain, Mike

2018-06-22

A video series presenting an overview of the Savannah River Site's (SRS) mission and operations. Each episode features a specific area/operation and how it contributes to help make the world safer. This episode features H Canyon's mission and operations. H Canyon and its adjoining H B Line facility represent the last full-scale radio chemical processing capabilities left in the United States.

Pollutant Dilution and Diffusion in Urban Street Canyon Neighboring Streets

NASA Astrophysics Data System (ADS)

Sun, Z.; Fu, Zh. M.

2011-09-01

In the present study we investigated the airflow patterns and air quality of a series of typical street canyon combinations, developed a mass balance model to determine the local pollutant dilution rate, and discuss the impact of upstream canyon on the air quality of downstream canyon. The results indicated that the geometrical size of upstream and downstream buildings have significant impacts on the ambient airflow patterns. The pollution distribution within the canyons varies with different building combinations and flow patterns. Within the upstream canyon, pollution always accumulates to the low building side for non-symmetrical canyon, and for symmetrical canyon high level of pollution occurs at the leeward side. The height of the middle and downstream buildings can evidently change the pollutant dispersion direction during the transport process. Within the polluted canyon, the pollutant dilution rate (PDR) also varies with different street canyon combinations. The highest PDR is observed when the upstream buildings are both low buildings no matter the height of downstream building. However, the two cases are likely to contribution pollution to the downstream canyon. The H-L-H combination is mostly against local pollution remove, while the L-H-L case is considered the best optimistic building combination with both the ability of diluting local pollution and not remarkably decreasing air quality of downstream canyon. The current work is expected instructive for city designers to optimize traffic patterns under typical existing geometry or in the development of urban geometry modification for air quality control.

Anatomy of La Jolla submarine canyon system; offshore southern California

USGS Publications Warehouse

Paull, C.K.; Caress, D.W.; Lundsten, E.; Gwiazda, R.; Anderson, K.; McGann, M.; Conrad, J.; Edwards, B.; Sumner, E.J.

2013-01-01

An autonomous underwater vehicle (AUV) carrying a multibeam sonar and a chirp profiler was used to map sections of the seafloor within the La Jolla Canyon, offshore southern California, at sub-meter scales. Close-up observations and sampling were conducted during remotely operated vehicle (ROV) dives. Minisparker seismic-reflection profiles from a surface ship help to define the overall geometry of the La Jolla Canyon especially with respect to the pre-canyon host sediments. The floor of the axial channel is covered with unconsolidated sand similar to the sand on the shelf near the canyon head, lacks outcrops of the pre-canyon host strata, has an almost constant slope of 1.0° and is covered with trains of crescent shaped bedforms. The presence of modern plant material entombed within these sands confirms that the axial channel is presently active. The sand on the canyon floor liquefied during vibracore collection and flowed downslope, illustrating that the sediment filling the channel can easily fail even on this gentle slope. Data from the canyon walls help constrain the age of the canyon and extent of incision. Horizontal beds of moderately cohesive fine-grained sediments exposed on the steep canyon walls are consistently less than 1.232 million years old. The lateral continuity of seismic reflectors in minisparker profiles indicate that pre-canyon host strata extend uninterrupted from outside the canyon underneath some terraces within the canyon. Evidence of abandoned channels and point bar-like deposits are noticeably absent on the inside bend of channel meanders and in the subsurface of the terraces. While vibracores from the surface of terraces contain thin (< 10 cm) turbidites, they are inferred to be part of a veneer of recent sediment covering pre-canyon host sediments that underpin the terraces. The combined use of state of the art seafloor mapping and exploration tools provides a uniquely detailed view of the morphology within an active submarine canyon.

Bottom-trawling along submarine canyons impacts deep sedimentary regimes.

PubMed

Paradis, Sarah; Puig, Pere; Masqué, Pere; Juan-Díaz, Xènia; Martín, Jacobo; Palanques, Albert

2017-02-24

Many studies highlight that fish trawling activities cause seafloor erosion, but the assessment of the remobilization of surface sediments and its relocation is still not well documented. These impacts were examined along the flanks and axes of three headless submarine canyons incised on the Barcelona continental margin, where trawling fleets have been operating for decades. Trawled grounds along canyon flanks presented eroded and highly reworked surface sediments resulting from the passage of heavy trawling gear. Sedimentation rates on the upper canyon axes tripled and quadrupled its natural (i.e. pre-industrialization) values after a substantial increase in total horsepower of the operating trawling fleets between 1960 s and 1970 s. These impacts affected the upper canyon reaches next to fishing grounds, where sediment resuspended by trawling can be transported towards the canyon axes. This study highlights that bottom trawling has the capacity to alter natural sedimentary environments by promoting sediment-starved canyon flanks, and by enhancing sedimentation rates along the contiguous axes, independently of canyons' morphology. Considering the global mechanisation and offshore expansion of bottom trawling fisheries since the mid-20 th century, these sedimentary alterations may occur in many trawled canyons worldwide, with further ecological impacts on the trophic status of these non-resilient benthic communities.

Hot Canyon

ScienceCinema

None

2018-05-07

This historical film footage, originally produced in the early 1950s as part of a series by WOI-TV, shows atomic research at Ames Laboratory. The work was conducted in a special area of the Laboratory known as the "Hot Canyon".

Recreational impacts on Colorado River beaches in Glen Canyon, Arizona

NASA Astrophysics Data System (ADS)

Carothers, Steven W.; Johnson, Robert A.; Dolan, Robert

1984-07-01

Recreational impact was measured on eight beaches in Glen Canyon National Recreation Area and 15 beaches in Grand Canyon National Park using permanently located transects and plots. Recreational impact indices included densities of human trash and charcoal and a measure of sand discoloration due to charcoal. Significant increases in the indices occurred on several Glen Canyon beaches over a seven-month period. Sand discoloration became significantly higher over all Glen Canyon beaches during the same time period. All indices were significantly higher in Glen Canyon than on similar Grand Canyon beaches. These differences are probably due to differences in: (a) level of impacts tolerated by the respective management regimes and, (b) in the number of user days among the two National Park Service administrative units. Management alternatives are presented for reversing the present trends of recreational impact on Glen Canyon beaches.

Wind-Flow Patterns in the Grand Canyon as Revealed by Doppler Lidar.

NASA Astrophysics Data System (ADS)

Banta, Robert M.; Darby, Lisa S.; Kaufmann, Pirmin; Levinson, David H.; Zhu, Cui-Juan

1999-08-01

Many interesting flow patterns were found in the Grand Canyon by a scanning Doppler lidar deployed to the south rim during the 1990 Wintertime Visibility Study. Three are analyzed in this study: 1) flow reversal in the canyon, where the flow in the canyon was in the opposite direction from the flow above the canyon rim; 2) under strong, gusty flow from the southwest, the flow inside and above the canyon was from a similar direction and coupled; and 3) under light large-scale ambient flow, the lidar found evidence of local, thermally forced up- and down-canyon winds in the bottom of the canyon.On the days with flow reversal in the canyon, the strongest in-canyon flow response was found for days with northwesterly flow and a strong inversion at the canyon rim. The aerosol backscatter profiles were well mixed within the canyon but poorly mixed across the rim because of the inversion. The gusty southwest flow days showed strong evidence of vertical mixing across the rim both in the momentum and in the aerosol backscatter profiles, as one would expect in turbulent flow. The days with light ambient flow showed poor vertical mixing even inside the canyon, where the jet of down-canyon flow in the bottom of the canyon at night was often either cleaner or dirtier than the air in the upper portions of the canyon. In a case study presented, the light ambient flow regime ended with an intrusion of polluted, gusty, southwesterly flow. The polluted, high-backscatter air took several hours to mix into the upper parts of the canyon. An example is also given of high-backscatter air in the upper portions of the canyon being mixed rapidly down into a jet of cleaner air in the bottom of the canyon in just a few minutes.

The Wide Bay Canyon system: A case study of canyon morphology on the east Australian continental margin

NASA Astrophysics Data System (ADS)

Yu, P. W.; Hubble, T.; Airey, D.; Gallagher, S. J.; Clarke, S. L.

2014-12-01

A voyage was conducted aboard the RV Southern Surveyor in early 2013 to investigate the east Australian continental margin. From the continental slope of the Wide Bay region offshore Fraser Island, Queensland, Australia, remote sensing data and sediment samples were collected. Bathymetric data reveals that the continental slope of the region presents a mature canyon system. Eight dredge samples were recovered from the walls of Wide Bay Canyon and the adjacent, relatively intact continental slope along the entire length of the slope, from the start of the shelf break to the toe, in water depths ranging from 1100-2500 m. For these samples, sediment composition, biostratigraphic age, and bulk mineralogy data are reported. These slope-forming sediments are primarily comprised of calcareous sandy-silts. Occasional terrestrial plant fossils and minerals can be found in a mostly marine-fossiliferous composition, suggesting minor but significant riverine and aeolian input. Biostratigraphic dates extracted from the foraminiferal contents of these samples indicate that the intra-canyon and slope material was deposited between Middle Miocene to Pliocene, implying that the incision of this section of the margin and formation of the erosional features took place no earlier than the Pliocene. In conjunction with bathymetric data of the local continental slope, the depositional origins of this section of the east Australian continental margin, and the timing of major morphological events such as slope failure and canyon incision can be interpreted. The Wide Bay Canyon system can serve as a representative case study of local canyon formation, allowing a better understanding of the past or ongoing processes that are shaping the margin and giving way to similar morphologies.

Grand Canyon Humpback Chub Population Improving

USGS Publications Warehouse

Andersen, Matthew E.

2007-01-01

The humpback chub (Gila cypha) is a long-lived, freshwater fish found only in the Colorado River Basin. Physical adaptations-large adult body size, large predorsal hump, and small eyes-appear to have helped humpback chub evolve in the historically turbulent Colorado River. A variety of factors, including habitat alterations and the introduction of nonnative fishes, likely prompted the decline of native Colorado River fishes. Declining numbers propelled the humpback chub onto the Federal list of endangered species in 1967, and the species is today protected under the Endangered Species Act of 1973. Only six populations of humpback chub are currently known to exist, five in the Colorado River Basin above Lees Ferry, Ariz., and one in Grand Canyon, Ariz. The U.S. Geological Survey's Grand Canyon Monitoring and Research Center oversees monitoring and research activities for the Grand Canyon population under the auspices of the Glen Canyon Dam Adaptive Management Program (GCDAMP). Analysis of data collected through 2006 suggests that the number of adult (age 4+ years) humpback chub in Grand Canyon increased to approximately 6,000 fish in 2006, following an approximate 40-50 percent decline between 1989 and 2001. Increasing numbers of adult fish appear to be the result of steadily increasing numbers of juvenile fish reaching adulthood beginning in the mid- to late-1990s and continuing through at least 2002.

Geologic map of the Valle 30' x 60' quadrangle, Coconino County, northern Arizona

USGS Publications Warehouse

Billingsley, George H.; Felger, Tracey J.; Priest, Susan S.

2006-01-01

The geologic map of the Valle 30' x 60' quadrangle is the result of a cooperative effort between the U.S. Geological Survey and the National Park Service to provide geologic information for regional resource management and visitor information services for Grand Canyon National Park, Arizona. The map area encompasses approximately 1,960 sq.mi. within Coconino County, northern Arizona and is bounded by long 112 deg to 113 deg W. and lat 35 deg 30 min to 36 deg N. and lies within the southern Colorado Plateaus geologic province (herein Colorado Plateau). The map area is locally subdivided into four physiographic parts; (1) the Grand Canyon (Cataract Canyon and extreme northeast corner of the map area), (2) the Coconino Plateau, (3) the Mount Floyd Volcanic Field, and (4) the San Francisco Volcanic Field as defined by Billingsley and others, 1997. Elevations range from 7,460 ft (2,274 m) on the Coconino Plateau along State Highway 64 northeast corner of the map area, to about 4,200 ft (1,280 m) at the bottom of Cataract Canyon. Settlements within the map area include Tusayan and Valle, Arizona. State Highway 64 and U.S. Highway 180 provide access to the Tusayan and Valle areas. Indian Route 18 is a paved highway in the northwest corner of the map area that is maintained by the Hualapai and Havasupai Indian Tribes and leads from State Route 66 about 7 mi (11 km) east of Peach Springs, Arizona to Hualapai Hilltop, a parking lot just north of the map area at the rim of Cataract Canyon where visitors begin an 8 mi (13 km) hike into Havasupai, Arizona. Other remote parts of the map are accessed by two dirt roads, which are maintained by Coconino County, and by several unmaintained local ranch roads. Weather conditions restrict travel within the area and visitors must obtain permission to access a few local ranch lands in the south-central edge of the map area. Extra water and food are highly recommended when traveling in this remote region. Access into Cataract Canyon is

Effects of canyon geometry on the distribution of traffic-related air pollution in a large urban area: Implications of a multi-canyon air pollution dispersion model

NASA Astrophysics Data System (ADS)

Fu, Xiangwen; Liu, Junfeng; Ban-Weiss, George A.; Zhang, Jiachen; Huang, Xin; Ouyang, Bin; Popoola, Olalekan; Tao, Shu

2017-09-01

Street canyons are ubiquitous in urban areas. Traffic-related air pollutants in street canyons can adversely affect human health. In this study, an urban-scale traffic pollution dispersion model is developed considering street distribution, canyon geometry, background meteorology, traffic assignment, traffic emissions and air pollutant dispersion. In the model, vehicle exhausts generated from traffic flows first disperse inside street canyons along the micro-scale wind field generated by computational fluid dynamics (CFD) model. Then, pollutants leave the street canyon and further disperse over the urban area. On the basis of this model, the effects of canyon geometry on the distribution of NOx and CO from traffic emissions were studied over the center of Beijing. We found that an increase in building height leads to heavier pollution inside canyons and lower pollution outside canyons at pedestrian level, resulting in higher domain-averaged concentrations over the area. In addition, canyons with highly even or highly uneven building heights on each side of the street tend to lower the urban-scale air pollution concentrations at pedestrian level. Further, increasing street widths tends to lead to lower pollutant concentrations by reducing emissions and enhancing ventilation simultaneously. Our results indicate that canyon geometry strongly influences human exposure to traffic pollutants in the populated urban area. Carefully planning street layout and canyon geometry while considering traffic demand as well as local weather patterns may significantly reduce inhalation of unhealthy air by urban residents.

Characteristics of flow and reactive pollutant dispersion in urban street canyons

NASA Astrophysics Data System (ADS)

Park, Soo-Jin; Kim, Jae-Jin; Kim, Minjoong J.; Park, Rokjin J.; Cheong, Hyeong-Bin

2015-05-01

In this study, the effects of aspect ratio defined as the ratio of building height to street width on the dispersion of reactive pollutants in street canyons were investigated using a coupled CFD-chemistry model. Flow characteristics for different aspect ratios were analyzed first. For each aspect ratio, six emission scenarios with different VOC-NOX ratios were considered. One vortex was generated when the aspect ratio was less than 1.6 (shallow street canyon). When the aspect ratio was greater than 1.6 (deep street canyon), two vortices were formed in the street canyons. Comparing to previous studies on two-dimensional street canyons, the vortex center is slanted toward the upwind building and reverse and downward flows are dominant in street canyons. Near the street bottom, there is a marked difference in flow pattern between in shallow and deep street canyons. Near the street bottom, reverse and downward flows are dominant in shallow street canyon and flow convergence exists near the center of the deep street canyons, which induces a large difference in the NOX and O3 dispersion patterns in the street canyons. NOX concentrations are high near the street bottom and decreases with height. The O3 concentrations are low at high NO concentrations near the street bottom because of NO titration. At a low VOC-NOX ratio, the NO concentrations are sufficiently high to destroy large amount of O3 by titration, resulting in an O3 concentration in the street canyon much lower than the background concentration. At high VOC-NOX ratios, a small amount of O3 is destroyed by NO titration in the lower layer of the street canyons. However, in the upper layer, O3 is formed through the photolysis of NO2 by VOC degradation reactions. As the aspect ratio increases, NOX (O3) concentrations averaged over the street canyons decrease (increase) in the shallow street canyons. This is because outward flow becomes strong and NOX flux toward the outsides of the street canyons increases

Bottom-trawling along submarine canyons impacts deep sedimentary regimes

PubMed Central

Paradis, Sarah; Puig, Pere; Masqué, Pere; Juan-Díaz, Xènia; Martín, Jacobo; Palanques, Albert

2017-01-01

Many studies highlight that fish trawling activities cause seafloor erosion, but the assessment of the remobilization of surface sediments and its relocation is still not well documented. These impacts were examined along the flanks and axes of three headless submarine canyons incised on the Barcelona continental margin, where trawling fleets have been operating for decades. Trawled grounds along canyon flanks presented eroded and highly reworked surface sediments resulting from the passage of heavy trawling gear. Sedimentation rates on the upper canyon axes tripled and quadrupled its natural (i.e. pre-industrialization) values after a substantial increase in total horsepower of the operating trawling fleets between 1960 s and 1970 s. These impacts affected the upper canyon reaches next to fishing grounds, where sediment resuspended by trawling can be transported towards the canyon axes. This study highlights that bottom trawling has the capacity to alter natural sedimentary environments by promoting sediment-starved canyon flanks, and by enhancing sedimentation rates along the contiguous axes, independently of canyons’ morphology. Considering the global mechanisation and offshore expansion of bottom trawling fisheries since the mid-20th century, these sedimentary alterations may occur in many trawled canyons worldwide, with further ecological impacts on the trophic status of these non-resilient benthic communities. PMID:28233856

Bottom-trawling along submarine canyons impacts deep sedimentary regimes

NASA Astrophysics Data System (ADS)

Paradis, Sarah; Puig, Pere; Masqué, Pere; Juan-Díaz, Xènia; Martín, Jacobo; Palanques, Albert

2017-02-01

Many studies highlight that fish trawling activities cause seafloor erosion, but the assessment of the remobilization of surface sediments and its relocation is still not well documented. These impacts were examined along the flanks and axes of three headless submarine canyons incised on the Barcelona continental margin, where trawling fleets have been operating for decades. Trawled grounds along canyon flanks presented eroded and highly reworked surface sediments resulting from the passage of heavy trawling gear. Sedimentation rates on the upper canyon axes tripled and quadrupled its natural (i.e. pre-industrialization) values after a substantial increase in total horsepower of the operating trawling fleets between 1960 s and 1970 s. These impacts affected the upper canyon reaches next to fishing grounds, where sediment resuspended by trawling can be transported towards the canyon axes. This study highlights that bottom trawling has the capacity to alter natural sedimentary environments by promoting sediment-starved canyon flanks, and by enhancing sedimentation rates along the contiguous axes, independently of canyons’ morphology. Considering the global mechanisation and offshore expansion of bottom trawling fisheries since the mid-20th century, these sedimentary alterations may occur in many trawled canyons worldwide, with further ecological impacts on the trophic status of these non-resilient benthic communities.

Active geologic processes in Barrow Canyon, northeast Chukchi Sea

USGS Publications Warehouse

Eittreim, S.; Grantz, A.; Greenberg, J.

1982-01-01

Circulation patterns on the shelf and at the shelf break appear to dominate the Barrow Canyon system. The canyon's shelf portion underlies and is maintained by the Alaska Coastal Current (A.C.C.), which flows northeastward along the coast toward the northeast corner of the broad Chukchi Sea. Offshelf and onshelf advective processes are indicated by oceanographic measurements of other workers. These advective processes may play an important role in the production of bedforms that are found near the canyon head as well as in processes of erosion or non-deposition in the deeper canyon itself. Coarse sediments recovered from the canyon axis at 400 to 570 m indicate that there is presently significant flow along the canyon. The canyon hooks left at a point north of Point Barrow where the A.C.C. loses its coastal constriction. The left hook, as well as preferential west-wall erosion, continues down to the abyssal plain of the Canada Basin at 3800 m. A possible explanation for the preferential west-wall erosion along the canyon, at least for the upper few hundred meters, is that the occasional upwelling events, which cause nutrient-rich water to flow along the west wall would in turn cause larger populations of burrowing organisms to live there than on the east wall, and that these organisms cause high rates of bioerosion. This hypothesis assumes that the dominant factor in the canyon's erosion is biological activity, not current velocity. Sedimentary bedforms consisting of waves and furrows are formed in soft mud in a region on the shelf west of the canyon head; their presence there perhaps reflects: (a) the supply of fine suspended sediments delivered by the A.C.C. from sources to the south, probably the Yukon and other rivers draining northwestern Alaska; and (b) the westward transport of these suspended sediments by the prevailing Beaufort Gyre which flows along the outer shelf. ?? 1982.

Perspective view over the Grand Canyon, Arizona

NASA Image and Video Library

2001-10-22

This simulated true color perspective view over the Grand Canyon was created from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data acquired on May 12, 2000. The Grand Canyon Village is in the lower foreground; the Bright Angel Trail crosses the Tonto Platform, before dropping down to the Colorado Village and then to the Phantom Ranch (green area across the river). Bright Angel Canyon and the North Rim dominate the view. At the top center of the image the dark blue area with light blue haze is an active forest fire. http://photojournal.jpl.nasa.gov/catalog/PIA01908

Use of Composite Fingerprinting Technique to Determine Contribution of Paria River Sediments to Dam-Release Flood Deposits in Marble Canyon, Grand Canyon, Az

NASA Astrophysics Data System (ADS)

Chapman, K.; Parnell, R. A.; Smith, M. E.; Grams, P. E.; Mueller, E. R.

2015-12-01

The 1963 closure of Glen Canyon Dam drastically reduced the downstream sediment supply and altered daily flow regimes of the Colorado River through Grand Canyon, resulting in significant sandbar erosion downstream of the dam. Dam-release floods, known as High Flow Experiments (HFEs), have occurred six times since 1996 and are intended to rebuild Grand Canyon sandbars using tributary-supplied sediment. In Marble Canyon (first 100 km of Grand Canyon) the targeted tributary is the Paria River which supplies approximately 90% of the annual suspended sediment flux through Marble Canyon; the same input contributed less than 6% prior to the dam. Annual topographic surveys have established that HFEs are effective at rebuilding sandbars. However, the long-term viability of using HFEs for sandbar maintenance is dependent on a sustainable source of sediments comprising HFE deposits. Significant use of non-tributary, main-stem sediments (i.e. pre-dam sand stored in eddies or the channel bed) in HFE deposits would indicate reliance on a limited resource, and diminishing returns in the ability of HFEs to rebuild sandbars. In this study, we sampled vertically throughout 12 bars in Marble Canyon to document temporal and downstream changes in the proportion of sediment sourced from the Paria River during the 2013 and 2014 HFEs. Preliminary data suggest that heavy mineral compositions and concentrations of Ti, S, Cr and Rb, all of which are influenced by grainsize, could be sufficiently capable of differentiating Paria-derived and main-stem sediments when combined into a composite fingerprint (CF). A multivariate mixing model using these CFs quantitatively determines the contribution of Paria-derived sediment in each HFE deposit sample. Mixing model endmembers for non-Paria sand include pre-dam flood deposits in Glen and Marble Canyons, and Marble Canyon dredge samples. These results elucidate the role of contemporary versus legacy sediment in long-term sandbar maintenance.

Geologic map of the Grand Canyon 30' x 60' quadrangle, Coconino and Mohave Counties, northwestern Arizona

USGS Publications Warehouse

Billingsley, G.H.

2000-01-01

This digital map database, compiled from previously published and unpublished data as well as new mapping by the author, represents the general distribution of bedrock and surficial deposits in the map area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the Grand Canyon area. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:100,000 or smaller.

Geology of Bull Canyon quadrangle, Montrose and San Miguel counties, Colorado

USGS Publications Warehouse

Cater, Fred W.

1953-01-01

The Bull Canyon quadrangle is one of eighteen 7 1/2-minute quadrangles covering the principal carnotite-producing area of southwestern Colorado. The geology of these quadrangles was mapped by the U.S. Geological Survey for the Atomic Energy Commission as part of a comprehensive study of carnotite depots. The rocks exposed in the eighteen quadrangles consist of crystalline rocks of pre-Cambrian age and sedimentary rocks that range in age from late Paleozoic to Quaternary. Over much of the area the sedimentary rocks are flat lying, but in places the rocks are disrupted by high-angle faults and northwest-trending folds. Conspicuous among the folds are large anticlines having cores of intrusive salt and gypsum. Most of the carnotite deposits are confined to the Salt Wash sandstone member of the Jurassic Morrison formation. Within this sandstone, most of the deposits are spottily distributed through an arcuate zone known as the "Uravan Mineral Belt". Individual deposits range in size from irregular masses containing only a few tons of ore to large, tabular masses containing many thousands of tones. The ore consists largely of sandstone selectively impregnated and in part replaced by uranium and vanadium minerals. Most of the deposits appear to be related to certain sedimentary structures in sandstones of favorable composition.

Observations of environmental change in Grand Canyon, Arizona

USGS Publications Warehouse

Webb, Robert H.; Melis, Theodore S.; Valdez, Richard A.

2002-01-01

Few scientific data have been collected on pre-dam conditions of the Colorado River corridor through Grand Canyon National Park. Using historical diaries, interviews with pre-dam river runners (referred to as the ?Old Timers?), and historical scientific data and observations, we compiled anecdotal information on environmental change in Grand Canyon. The most significant changes are the: lowering of water temperature in the river, near-elimination of heavily sediment-laden flows, erosion of sand bars, invasion of non-native tamarisk trees, reduction in driftwood, development of marshes, increase in non-native fish at the expense of native fishes, and increase in water bird populations. In addition, few debris flows were observed before closure of Glen Canyon Dam, which might suggests that the frequency of debris flows in Grand Canyon has increased. Other possible changes include decreases in bat populations and increases in swallow and bighorn sheep populations, although the evidence is anecdotal and inconclusive. These results provide a perspective on managing the Colorado River that may allow differentiation of the effects of Glen Canyon Dam from other processes of change.

Grand Canyon, Lake Powell, and Lake Mead

NASA Technical Reports Server (NTRS)

2002-01-01

A snowfall in the American West provides contrast to the landscape's muted earth tones and indicates changes in topography and elevation across (clockwise from top left) Nevada, Utah, Colorado, New Mexico, Arizona, and California. In Utah, the southern ranges of the Wasatch Mountains are covered in snow, and the Colorado River etches a dark ribbon across the red rock of the Colorado Plateau. In the center of the image is the reservoir created by the Glen Canyon Dam. To the east are the gray-colored slopes of Navaho Mountain, and to the southeast, dusted with snow is the region called Black Mesa. Southwest of Glen Canyon, the Colorado enters the Grand Canyon, which cuts westward through Arizona. At a deep bend in the river, the higher elevations of the Keibab Plateau have held onto snow. At the end of the Grand Canyon lies another large reservoir, Lake Mead, which is formed by the Hoover Dam. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Amphitheater-headed canyons formed by megaflooding at Malad Gorge, Idaho

PubMed Central

Lamb, Michael P.; Mackey, Benjamin H.; Farley, Kenneth A.

2014-01-01

Many bedrock canyons on Earth and Mars were eroded by upstream propagating headwalls, and a prominent goal in geomorphology and planetary science is to determine formation processes from canyon morphology. A diagnostic link between process and form remains highly controversial, however, and field investigations that isolate controls on canyon morphology are needed. Here we investigate the origin of Malad Gorge, Idaho, a canyon system cut into basalt with three remarkably distinct heads: two with amphitheater headwalls and the third housing the active Wood River and ending in a 7% grade knickzone. Scoured rims of the headwalls, relict plunge pools, sediment-transport constraints, and cosmogenic (3He) exposure ages indicate formation of the amphitheater-headed canyons by large-scale flooding ∼46 ka, coeval with formation of Box Canyon 18 km to the south as well as the eruption of McKinney Butte Basalt, suggesting widespread canyon formation following lava-flow diversion of the paleo-Wood River. Exposure ages within the knickzone-headed canyon indicate progressive upstream younging of strath terraces and a knickzone propagation rate of 2.5 cm/y over at least the past 33 ka. Results point to a potential diagnostic link between vertical amphitheater headwalls in basalt and rapid erosion during megaflooding due to the onset of block toppling, rather than previous interpretations of seepage erosion, with implications for quantifying the early hydrosphere of Mars. PMID:24344293

Crossing fitness canyons by a finite population

NASA Astrophysics Data System (ADS)

Saakian, David B.; Bratus, Alexander S.; Hu, Chin-Kun

2017-06-01

We consider the Wright-Fisher model of the finite population evolution on a fitness landscape defined in the sequence space by a path of nearly neutral mutations. We study a specific structure of the fitness landscape: One of the intermediate mutations on the mutation path results in either a large fitness value (climbing up a fitness hill) or a low fitness value (crossing a fitness canyon), the rest of the mutations besides the last one are neutral, and the last sequence has much higher fitness than any intermediate sequence. We derive analytical formulas for the first arrival time of the mutant with two point mutations. For the first arrival problem for the further mutants in the case of canyon crossing, we analytically deduce how the mean first arrival time scales with the population size and fitness difference. The location of the canyon on the path of sequences has a crucial role. If the canyon is at the beginning of the path, then it significantly prolongs the first arrival time; otherwise it just slightly changes it. Furthermore, the fitness hill at the beginning of the path strongly prolongs the arrival time period; however, the hill located near the end of the path shortens it. We optimize the first arrival time by applying a nonzero selection to the intermediate sequences. We extend our results and provide a scaling for the valley crossing time via the depth of the canyon and population size in the case of a fitness canyon at the first position. Our approach is useful for understanding some complex evolution systems, e.g., the evolution of cancer.

[Effect of greenbelt on pollutant dispersion in street canyon].

PubMed

Xu, Wei-Jia; Xing, Hong; Yu, Zhi

2012-02-01

The effect feature of greenbelt on flow field and pollutant dispersion in urban street canyon was researched. The greenbelt was assumed as uniform porous media and its aerodynamics property defined by the pressure loss coefficient. Subsequently, the pollutant dispersion in the street canyon of which there was greenbelt in the middle was simulated with the steady-state standard kappa-epsilon turbulence model and species transport equation. The simulated results agreed well with the wind-tunnel data. Compared with the treeless case, it finds that the street canyon contain a clockwise vortex, the pollutant concentration of the leeward was several times than the windward and the growth rate of pollutant concentration was 46.0%. The further simulation for the impact of tree crown position on the airflow and pollutant dispersion finds that the height of major vortex center in the street canyon increases with the height of tree crown and gradually closes the top of windward building This causes that the average wind speed in the street canyon decreases. Especially when the top of tree crown over the roof and hinder the air flow above the street canyon, the average pollutant concentration increases with the height of tree crown rapidly.

An analysis of the potential for Glen Canyon Dam releases to inundate archaeological sites in the Grand Canyon, Arizona

USGS Publications Warehouse

Sondossi, Hoda A.; Fairley, Helen C.

2014-01-01

The development of a one-dimensional flow-routing model for the Colorado River between Lees Ferry and Diamond Creek, Arizona in 2008 provided a potentially useful tool for assessing the degree to which varying discharges from Glen Canyon Dam may inundate terrestrial environments and potentially affect resources located within the zone of inundation. Using outputs from the model, a geographic information system analysis was completed to evaluate the degree to which flows from Glen Canyon Dam might inundate archaeological sites located along the Colorado River in the Grand Canyon. The analysis indicates that between 4 and 19 sites could be partially inundated by flows released from Glen Canyon Dam under current (2014) operating guidelines, and as many as 82 archaeological sites may have been inundated to varying degrees by uncontrolled high flows released in June 1983. Additionally, the analysis indicates that more of the sites currently (2014) proposed for active management by the National Park Service are located at low elevations and, therefore, tend to be more susceptible to potential inundation effects than sites not currently (2014) targeted for management actions, although the potential for inundation occurs in both groups of sites. Because of several potential sources of error and uncertainty associated with the model and with limitations of the archaeological data used in this analysis, the results are not unequivocal. These caveats, along with the fact that dam-related impacts can involve more than surface-inundation effects, suggest that the results of this analysis should be used with caution to infer potential effects of Glen Canyon Dam on archaeological sites in the Grand Canyon.

Geomorphic Thresholds of Submarine Canyons Along the U.S. Atlantic Continental Margin

NASA Astrophysics Data System (ADS)

Brothers, D. S.; ten Brink, U. S.; Andrews, B. D.; Chaytor, J. D.

2011-12-01

Vast networks of submarine canyons and associated channels are incised into the U.S. Atlantic continental slope and rise. Submarine canyons form by differential erosion and deposition, primarily from sedimentary turbidity flows. Theoretical and laboratory studies have investigated the initiation of turbidity flows and their capacity to erode and entrain sedimentary material at distances far from the shelf edge. The results have helped understand the nature of turbidite deposits on the continental slope and rise. Nevertheless, few studies have examined the linkages between down-canyon sediment transport and the morphology of canyon/channel networks using mesoscale analyses of swath bathymetry data. We present quantitative analysis of 100-m resolution multibeam bathymetry data spanning ~616,000 km2 of the slope and rise between Georges Banks and the Blake Plateau (New England to North Carolina). Canyons are categorized as shelf-indenting or slope-confined based on spatial scale, vertical relief and connection with terrestrial river systems during sea level low stands. Shelf-indenting canyons usually represent the trunk-canyon of submerged channel networks. On the rise, shelf-indenting canyons have relatively well-developed channel-levees and sharp inner-thalwag incision suggesting much higher frequency and volume of turbidity flows. Because of the similarities between submarine canyon networks and terrestrial river systems, we apply methods originally developed to study fluvial morphology. Along-canyon profiles are extracted from the bathymetry data and the power-law relationship between thalwag gradient and drainage area is examined for more than 180 canyons along an ~1200 km stretch of the US Atlantic margin. We observe distinct thresholds in the power-law relationship between drainage area and gradient. Almost all canyons with heads on the upper slope contain at least two linear segments when plotted in log-log form. The first segment along the upper slope is flat

Spatial and Temporal Variation in DeSoto Canyon Macrofaunal Community Structure

NASA Astrophysics Data System (ADS)

Baco-Taylor, A.; Shantharam, A. K.

2016-02-01

Sediment-dwelling macrofauna (polychaetes, bivalves, and assorted crustaceans ≥ 300 µm) have long served as biological indicators of ecosystem stress. As part of evaluating the 2010 impact from the Deepwater Horizon blowout, we sampled 12 sites along and transverse to the DeSoto Canyon axis, Gulf of Mexico, as well as 2 control sites outside the Canyon. Sites ranged in depth from 479-2310 m. Three of the sites (PCB06, S36, and XC4) were sampled annually from 2012-2014. We provide an overview of the macrofauna community structure of canyon and non-canyon sites, as well as trends in community structure and diversity at the time-series sites. Compositionally, polychaetes dominated the communities, followed by tanaid crustaceans and bivalves. The total number of individuals was not significantly correlated with depth while the total number of taxa and species richness were. Rarefaction shows the deepest station, XC4 (2310 m) had the lowest diversity while NT800 (a non-canyon control at 800m) had the highest. Multivariate analysis shows the canyon assemblages fall into eight clusters with the non-canyon stations forming a separate ninth cluster, indicating a detectable difference in canyon and non-canyon communities. Time series stations show an increase in diversity from 2012-2014 with a strong overlap in community structure in 2013 and 2014 samples. Environmental analysis, via BEST, using data from 10 canyon sites and the controls, indicated depth in combination with latitude explain the most variation in macrofaunal community structure.

Modern landscape processes affecting archaeological sites along the Colorado River corridor downstream of Glen Canyon Dam, Glen Canyon National Recreation Area, Arizona

USGS Publications Warehouse

East, Amy E.; Sankey, Joel B.; Fairley, Helen C.; Caster, Joshua J.; Kasprak, Alan

2017-08-29

The landscape of the Colorado River through Glen Canyon National Recreation Area formed over many thousands of years and was modified substantially after the completion of Glen Canyon Dam in 1963. Changes to river flow, sediment supply, channel base level, lateral extent of sedimentary terraces, and vegetation in the post-dam era have modified the river-corridor landscape and have altered the effects of geologic processes that continue to shape the landscape and its cultural resources. The Glen Canyon reach of the Colorado River downstream of Glen Canyon Dam hosts many archaeological sites that are prone to erosion in this changing landscape. This study uses field evaluations from 2016 and aerial photographs from 1952, 1973, 1984, and 1996 to characterize changes in potential windblown sand supply and drainage configuration that have occurred over more than six decades at 54 archaeological sites in Glen Canyon and uppermost Marble Canyon. To assess landscape change at these sites, we use two complementary geomorphic classification systems. The first evaluates the potential for aeolian (windblown) transport of river-derived sand from the active river channel to higher elevation archaeological sites. The second identifies whether rills, gullies, or arroyos (that is, overland drainages that erode the ground surface) exist at the archaeological sites as well as the geomorphic surface, and therefore the relative base level, to which those flow paths drain. Results of these assessments are intended to aid in the management of irreplaceable archaeological resources by the National Park Service and stakeholders of the Glen Canyon Dam Adaptive Management Program.

NASA Satellite Reveals Grandeur of Arizona Grand Canyon

NASA Image and Video Library

2011-10-14

Arguably one of America most magnificent national parks is the Grand Canyon in northern Arizona. NASA Terra spacecraft captured this image looking to the northeast, the buildings and roads in the center foreground are Grand Canyon Village.

Distribution and transport of suspended particulate matter in Monterey Canyon, California

USGS Publications Warehouse

Xu, J. P.; Noble, M.; Eittreim, S.L.; Rosenfeld, L.K.; Schwing, F.B.; Pilskaln, C.H.

2002-01-01

From August 1993 to August 1994, six moorings that measure current, temperature, salinity, and water clarity were deployed along the axis of Monterey Canyon to study the circulation and transport of water and suspended particulate matter through the canyon system. The moorings occupied three sites that are morphologically different: a narrow transverse section (axis width 900 m) at 1450 m water depth, a wide transverse section at 2837 m, and a third site in the fan valley axis farther offshore at 3223 m that recorded for 3 yr. In addition, CTD/transmissometer casts were conducted within and near the Monterey Canyon during four cruises. Our data show a mainly biogenic, surface turbid layer, a limited intermediate nepheloid layer, and a bottom nepheloid layer. There is a consistent presence of a turbid layer within the canyon at a water depth of about 1500 m. Tidal flow dominates at all sites, but currents above the canyon rim and within the canyon appear to belong to two distinct dynamic systems. Bottom intensification of currents plays an important role in raising the near-bottom shear stress high enough that bottom sediments are often, if not always, resuspended. Mean flow pattern suggests a convergence zone between the narrow and wide site: the near-bed (100 m above bottom where the lowest current meter was located) mean transport is down-canyon at the 1450-m site, while the near-bottom transport at the 2837-m site is up-canyon, at a smaller magnitude. Transport at the 3223-m site is dominantly NNW, cross-canyon, with periods of up-canyon flow over 3 yr. A very high-turbidity event was recorded 100 m above the canyon bottom at the narrow site. The event started very abruptly and lasted more than a week. This event was not detected at either of the deeper sites. A canyon head flushing event is likely the cause. ?? 2002 Elsevier Science B.V. All rights reserved.

Geologic Map of the House Rock Valley Area, Coconino County, Northern Arizona

USGS Publications Warehouse

Billingsley, George H.; Priest, Susan S.

2010-01-01

This geologic map is a cooperative effort of the U.S. Geological Survey (USGS), the Bureau of Land Management, the National Park Service, and the U.S. Forest Service to provide a geologic database for resource management officials and visitor information services. This map was produced in response to information needs related to a proposed withdrawal of three segregated land areas near Grand Canyon National Park, Arizona, from new hard rock mining activity. House Rock Valley was designated as the east parcel of the segregated lands near the Grand Canyon. This map was needed to provide connectivity for the geologic framework of the Grand Canyon segregated land areas. This geologic map of the House Rock Valley area encompasses approximately 280 mi2 (85.4 km2) within Coconino County, northern Arizona, and is bounded by longitude 111 degrees 37'30' to 112 degrees 05' W. and latitude 36 degrees 30' to 36 degrees 50' N. The map area is in the eastern part of the Arizona Strip, which lies within the southern Colorado Plateaus geologic province (herein Colorado Plateau). The Arizona Strip is the part of Arizona lying north of the Colorado River. The map is bound on the east by the Colorado River in Marble Canyon within Grand Canyon National Park and Glen Canyon National Recreation Area, on the south and west by the Kaibab National Forest and Grand Canyon National Game Preserve, and on the north by the Vermilion Cliffs Natural Area, the Paria Canyon Vermilion Cliffs Wilderness Area, and the Vermilion Cliffs National Monument. House Rock State Buffalo Ranch also bounds the southern edge of the map area. The Bureau of Land Management Arizona Field Office in St. George, Utah, manages public lands of the Vermilion Cliffs Natural Area, Paria Canyon - Vermilion Cliffs Wilderness and Vermilion Cliffs National Monument. The North Kaibab Ranger District in Fredonia, Arizona, manages U.S. Forest Service land along the west edge of the map area and House Rock State Buffalo Ranch

Strategic guidelines for street canyon geometry to achieve sustainable street air quality

NASA Astrophysics Data System (ADS)

Chan, Andy T.; So, Ellen S. P.; Samad, Subash C.

This paper is concerned with the motion of air within the urban street canyon and is directed towards a deeper understanding of pollutant dispersion with respect to various simple canyon geometries and source positions. Taking into account the present days typical urban configurations, three principal flow regimes "isolated roughness flow", "skimming flow" and "wake interference flow" (Boundary Layer Climates, 2nd edition, Methuen, London) and their corresponding pollutant dispersion characteristics are studied for various canopies aspect ratios, namely relative height ( h2/ h1), canyon height to width ratio ( h/ w) and canyon length to height ratio ( l/ h). A field-size canyon has been analyzed through numerical simulations using the standard k- ɛ turbulence closure model. It is found that the pollutant transport and diffusion is strongly dependent upon the type of flow regime inside the canyon and exchange between canyon and the above roof air. Some rules of thumbs have been established to get urban canyon geometries for efficient dispersion of pollutants.

Wildfire-Migration Dynamics: Lessons from Colorado’s Fourmile Canyon Fire

PubMed Central

Nawrotzki, Raphael J.; Brenkert-Smith, Hannah; Hunter, Lori M.; Champ, Patricia A.

2014-01-01

The number of people living in wildfire prone wildland-urban interface (WUI) communities is on the rise. Yet, no prior study has investigated wildfire-induced residential relocation from WUI areas after a major fire event. To provide insight into the association between socio-demographic and socio-psychological characteristics and wildfire related intention to move, we use data from a survey of WUI residents in Boulder and Larimer Counties, Colorado. The data were collected two months after the devastating Fourmile Canyon fire destroyed 169 homes and burned over 6,000 acres of public and private land. Although working with a small migrant sample, logistic regression models demonstrate that survey respondents intending to move in relation to wildfire incidence do not differ socio-demographically from their non-migrant counterparts. They do, however, show significantly higher levels of risk perception. Investigating destination choices shows a preference for short distance moves. PMID:24882943

Telegraph Canyon Creek, City of Chula Vista, San Diego County, California. Detailed Report for Flood Control. Volume 2. Technical Appendixes.

DTIC Science & Technology

1983-07-01

occurred within 40 miles of’ the site. Most of these earthquakes appear to be related to activity on the Elsinore, Agua Caliente, and offshore faults. The...device would be required by the Sweetwater Authority to prevent contamination of potable water lines. TELEGRAPH CANYON CREEK - - Recommended Plant List A

Progress report on the Happy Jack mine, Which Canyon area, San Juan county, Utah

USGS Publications Warehouse

Trites, Albert F.; Chew, Randall T.

1954-01-01

The Happy Jack mine is in the White Canyon area, San Juan county, Utah. Production is from high-grade uranium deposits in the Shinarump conglomerate of the Triassic age. In this area the Shinarump beds range from about 16 to 40 feet in thickness and the lower part of these beds fills an east-trending channel this is note than 750 feet wide and 10 feet deep. The Shinarump conglomerate consists of beds of coarse- to fine-grained quartzose sandstone, conglomerate, siltstone, and claystone. Carbonized wood is abundant in these beds, and in the field it was classified as mineral charcoal and coal. Intra-Shinarump channels, cross-stratification, current lineation, and slumping and compaction structures have been recognized in the mine. Steeply dipping fractures have dominant trends in four directions -- N 65°W, N 60°E, N 85°E, and due north. Uranium occurs as bedded deposits, as replacement bodies in accumulations of "trash", and as replacements of larger fragments of wood. An "ore shoot" is formed where the three types of uranium deposits occur together; these ore shoots appear to be elongate masses with sharp boundaries. Uranium minerals include uraninite, sooty pitchblende(?), and the sulfate--betazippeite, johannite, and uranopilite. Associated with the uraninite are the sulfide minerals covellite, bornite, chalcopyritw, and pyrite. Galena and sphalerite have been found in close association with uranium minerals. The gaunge minerals include: limonite and hematite present in most of the sandstone beds throughout the deposit, jarosite that impregnates much of the sandstone in the outer parts of the mine workings, gypsum that fills many of the fractures, and barite that impregnates the sandstone in at least one part of the mine. Secondary copper minerals, mainly copper sulfates, occur throughout the mine, but most abundant near the adits in the outermost 30 feet of the workings. The minerals comprising the bulk of the country rock include quartz, feldspar, and clay

Geology of the head of Lydonia Canyon, U.S. Atlantic outer continental shelf

USGS Publications Warehouse

Twichell, David C.

1983-01-01

The geology of the part of Lydonia Canyon shoreward of the continental shelf edge on the southern side of Georges Bank was mapped using high-resolution seismic-reflection and side-scan sonar techniques and surface sediment grab samples. The head of the canyon incises Pleistocene deltaic deposits and Miocene shallow marine strata. Medium sand containing some coarse sand and gravel covers the shelf except for a belt of very fine sand containing no gravel on either side of the canyon in water depths of 125–140 m. Gravel and boulders, presumably ice-rafted debris, cover the rim of the canyon. The canyon floor and canyon wall gullies are covered by coarse silt of Holocene age which is as much as 25 m thick, and Miocene and Pleistocene strata are exposed on the spurs between gullies. The Holocene sediment is restricted to the canyon shoreward of the shelf edge and has been winnowed from the shelf. Furrows cut in the shelf sands and ripples on the shelf and in the canyon suggest that sediment continues to be moved in this area. Sediment distribution, however, is inconsistent with that expected from the inferred westward sediment transport on the shelf. Either the fine-grained deposits on the shelf to either side of the canyon head are relict or there is a significant component of offshore transport around the canyon head.In the head of Oceanographer Canyon, only 40 km west of Lydonia Canyon, present conditions are strikingly different. The floor of Oceanographer Canyon is covered by sand waves, and their presence indicates active reworking of the bottom sediments by strong currents. The close proximity of the two canyons suggests that the relative importance of processes acting in canyons can be variable over short distances.

Status of the desert tortoise in Red Rock Canyon State Park

USGS Publications Warehouse

Berry, Kristin H.; Keith, Kevin; Bailey, Tracy Y.

2008-01-01

We surveyed for desert tortoises, Gopherus agassizii, in the western part of Red Rock Canyon State Park and watershed in eastern Kern County, California, between 2002 and 2004. We used two techniques: a single demographic plot (~4 km2 ) and 37 landscape plots (1-ha each). We estimated population densities of tortoises to be between 2.7 and 3.57/km2 and the population in the Park to be 108 tortoises. We estimated the death rate at 67% for subadults and adults during the last 4 yrs. Mortality was high for several reasons: gunshot deaths, avian predation, mammalian predation, and probably disease. Historic and recent anthropogenic impacts from State Highway 14, secondary roads, trash, cross-country vehicle tracks, and livestock have contributed to elevated death rates and degradation of habitat. We propose conservation actions to reduce mortality.

H CANYON PROCESSING IN CORRELATION WITH FH ANALYTICAL LABS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weinheimer, E.

2012-08-06

Management of radioactive chemical waste can be a complicated business. H Canyon and F/H Analytical Labs are two facilities present at the Savannah River Site in Aiken, SC that are at the forefront. In fact H Canyon is the only large-scale radiochemical processing facility in the United States and this processing is only enhanced by the aid given from F/H Analytical Labs. As H Canyon processes incoming materials, F/H Labs provide support through a variety of chemical analyses. Necessary checks of the chemical makeup, processing, and accountability of the samples taken from H Canyon process tanks are performed at themore » labs along with further checks on waste leaving the canyon after processing. Used nuclear material taken in by the canyon is actually not waste. Only a small portion of the radioactive material itself is actually consumed in nuclear reactors. As a result various radioactive elements such as Uranium, Plutonium and Neptunium are commonly found in waste and may be useful to recover. Specific processing is needed to allow for separation of these products from the waste. This is H Canyon's specialty. Furthermore, H Canyon has the capacity to initiate the process for weapons-grade nuclear material to be converted into nuclear fuel. This is one of the main campaigns being set up for the fall of 2012. Once usable material is separated and purified of impurities such as fission products, it can be converted to an oxide and ultimately turned into commercial fuel. The processing of weapons-grade material for commercial fuel is important in the necessary disposition of plutonium. Another processing campaign to start in the fall in H Canyon involves the reprocessing of used nuclear fuel for disposal in improved containment units. The importance of this campaign involves the proper disposal of nuclear waste in order to ensure the safety and well-being of future generations and the environment. As processing proceeds in the fall, H Canyon will have a

27 CFR 9.152 - Malibu-Newton Canyon.

Code of Federal Regulations, 2010 CFR

2010-04-01

....” (2) Then south along Kanan Dume Road to the point where an unnamed, unimproved dirt road referred to... Canyon Road to an unnamed, unimproved dirt road referred to by the petitioner as Newton Mountain Way at... southeastern ridgeline of Newton Canyon, to an unnamed, unimproved dirt road referred to by the petitioner as...

Sediment Dating With 210Pb and 137Cs In Monterey Canyon, California Reveal the extent of recent sediment movement down canyon

NASA Astrophysics Data System (ADS)

Lorenson, T. D.; Maier, K. L.; Gwiazda, R.; Paull, C. K.; McGann, M.

2017-12-01

Submarine canyons are major vectors of sediment transport off the continent into the deep sea. Recent results from the Monterey Coordinated Canyon Experiment document fifteen sediment transport events occurred during an 18-month period from 2015 to 2017, and three of them reached at least to 1850m. In an attempt to constrain the timing and rate in which sediments were transported down canyons in these and earlier events we have collected sediment cores and measured the sedimentation rates using 210Pb and 137Cs dating techniques along the axis of Monterey Canyon. We employed transects of precisely located ROV collected push cores and vibracores collected at water depths ranging from 300m to 2900m perpendicular to the canyon axis using a remotely operated vehicle (ROV). Some cores were taken in 2013 and compared with those taken in 2017. We focused on cores from terraces that are between 60m and 75m above the canyon thalweg in water depths between 300 and 1500 m and in cores collected form the canyon's axial channel between 1800 and 2900 m water depths where the canyon widens considerably. Generally sedimentation rates vary with depth, with the highest sedimentation rate closest to land, but vary substantially across successive terraces. Sawtooth-shaped excess 210Pb and 137Cs profiles with depth at almost all sites at least to 1500m imply several episodes of deposition and reworking of sediment on the terraces suggesting multiple sediment transport events. The excess 210Pb in many cores reach depths of up to 1m implying sedimentation rates greater than 10mm per year. At the deepest site (2900m) about 10 cm of fine hemipelagic sediment overlies sand indicating a high-energy sediment flow event. In 2014 the measured 210Pb sedimentation rate of 0.6 to 0.8mm per year indicates that the last 10 cm of sediment have been deposited and undisturbed since about the year 1910 showing that recent events have not reached this depth. Measurements are on going to determine if the

Dispersion and photochemical evolution of reactive pollutants in street canyons

NASA Astrophysics Data System (ADS)

Kwak, Kyung-Hwan; Baik, Jong-Jin; Lee, Kwang-Yeon

2013-05-01

Dispersion and photochemical evolution of reactive pollutants in street canyons with canyon aspect ratios of 1 and 2 are investigated using a computational fluid dynamics (CFD) model coupled with the carbon bond mechanism IV (CBM-IV). Photochemical ages of NOx and VOC are expressed as a function of the NO2-to-NOx and toluene-to-xylene ratios, respectively. These are found to be useful for analyzing the O3 and OH oxidation processes in the street canyons. The OH oxidation process (O3 oxidation process) is more pronounced in the upper (lower) region of the street canyon with a canyon aspect ratio of 2, which is characterized by more (less) aged air. In the upper region of the street canyon, O3 is chemically produced as well as transported downward across the roof level, whereas O3 is chemically reduced in the lower region of the street canyon. The O3 chemical production is generally favorable when the normalized photochemical ages of NOx and VOC are larger than 0.55 and 0.28, respectively. The sensitivities of O3 chemical characteristics to NOx and VOC emission rates, photolysis rate, and ambient wind speed are examined for the lower and upper regions of the street canyon with a canyon aspect ratio of 2. The O3 concentration and the O3 chemical production rate divided by the O3 concentration increase as the NOx emission rate decreases and the VOC emission rate and photolysis rate increase. The O3 concentration is less sensitive to the ambient wind speed than to other factors considered. The relative importance of the OH oxidation process compared to the O3 oxidation process increases with increasing NOx emission rate and photolysis rate and decreasing VOC emission rate. In this study, both O3 and OH oxidation processes are found to be important in street-canyon scale chemistry. The methodology of estimating the photochemical ages can potentially be adopted to neighborhood scale chemistry.

Populating a Control Point Database: A cooperative effort between the USGS, Grand Canyon Monitoring and Research Center and the Grand Canyon Youth Organization

NASA Astrophysics Data System (ADS)

Brown, K. M.; Fritzinger, C.; Wharton, E.

2004-12-01

The Grand Canyon Monitoring and Research Center measures the effects of Glen Canyon Dam operations on the resources along the Colorado River from Glen Canyon Dam to Lake Mead in support of the Grand Canyon Adaptive Management Program. Control points are integral for geo-referencing the myriad of data collected in the Grand Canyon including aerial photography, topographic and bathymetric data used for classification and change-detection analysis of physical, biologic and cultural resources. The survey department has compiled a list of 870 control points installed by various organizations needing to establish a consistent reference for data collected at field sites along the 240 mile stretch of Colorado River in the Grand Canyon. This list is the foundation for the Control Point Database established primarily for researchers, to locate control points and independently geo-reference collected field data. The database has the potential to be a valuable mapping tool for assisting researchers to easily locate a control point and reduce the occurrance of unknowingly installing new control points within close proximity of an existing control point. The database is missing photographs and accurate site description information. Current site descriptions do not accurately define the location of the point but refer to the project that used the point, or some other interesting fact associated with the point. The Grand Canyon Monitoring and Research Center (GCMRC) resolved this problem by turning the data collection effort into an educational exercise for the participants of the Grand Canyon Youth organization. Grand Canyon Youth is a non-profit organization providing experiential education for middle and high school aged youth. GCMRC and the Grand Canyon Youth formed a partnership where GCMRC provided the logistical support, equipment, and training to conduct the field work, and the Grand Canyon Youth provided the time and personnel to complete the field work. Two data

Physiographic rim of the Grand Canyon, Arizona: a digital database

USGS Publications Warehouse

Billingsley, George H.; Hampton, Haydee M.

1999-01-01

This Open-File report is a digital physiographic map database. This pamphlet serves to introduce and describe the digital data. There is no paper map included in the Open-File report. The report does include, however, PostScript and PDF format plot files, each containing an image of the map. For those interested in a paper plot of information contained in the database or in obtaining the PostScript plot files, please see the section entitled "For Those Who Don't Use Digital Geologic Map Databases" below. This physiographic map of the Grand Canyon is modified from previous versions by Billingsley and Hendricks (1989), and Billingsley and others (1997). The boundary is drawn approximately along the topographic rim of the Grand Canyon and its tributary canyons between Lees Ferry and Lake Mead (shown in red). Several isolated small mesas, buttes, and plateaus are within this area, which overall encompasses about 2,600 square miles. The Grand Canyon lies within the southwestern part of the Colorado Plateaus of northern Arizona between Lees Ferry, Colorado River Mile 0, and Lake Mead, Colorado River Mile 277. The Colorado River is the corridor for raft trips through the Grand Canyon. Limestone rocks of the Kaibab Formation form most of the north and south rims of the Grand Canyon, and a few volcanic rocks form the north rim of parts of the Uinkaret and Shivwits Plateaus. Limestones of the Redwall Limestone and lower Supai Group form the rim of the Hualapai Plateau area, and Limestones of Devonian and Cambrian age form the boundary rim near the mouth of Grand Canyon at the Lake Mead. The natural physiographic boundary of the Grand Canyon is roughly the area a visitor would first view any part of the Grand Canyon and its tributaries.

Shelf-Slope Exchanges near Submarine Canyons in the Southern Mid-Atlantic Bight

NASA Astrophysics Data System (ADS)

Wang, H.; Gong, D.

2016-02-01

Shelf-slope exchange processes are major physical drivers of biological productivity near the shelf-break. Observations from two Slocum ocean gliders in Fall 2013 are used to explore the driving mechanisms of cross-shelf-slope exchanges near Norfolk Canyon and Washington Canyon in the southern Mid-Atlantic Bight. Offshore excursion of bottom "cold pool" water, and shoreward intrusion of slope water at surface layer and thermocline depth occurred during northeasterly along-shelf winds. The saline intrusions of surface slope water resided between the cold pool and surface shelf water, and reached the bottom on the outer and mid-shelf, while the offshore excursion of cold pool water was found between the surface and intermediate slope-water over the canyon. Ekman transport calculation shows wind-driven cross-shelf transport can partially explain this interleaving pattern of intrusions. Scaling analysis of double diffusive processes demonstrate that they also likely played a role in the cross-shelf-slope exchange. A unique canyon upwelling event was captured in and around Washington Canyon during a period of southwesterly along-shelf wind and along-shelf flow to the northeast. The water mass distributions and isopycnal responses in both along-canyon and cross-canyon transects are consistent with scaling analysis and numerical studies of canyon upwelling. Temperature-Salinity properties of water masses in the canyon suggest active mixing between shelf and slope water masses near the canyon head. These results point to the importance of wind, double diffusion, and canyon topography on shelf-slope exchange in the MAB.

Evolution and Submarine Landslide Potential of Monterey Canyon Head, Offshore Central California

NASA Astrophysics Data System (ADS)

Maier, K. L.; Johnson, S. Y.; Hart, P. E.; Hartwell, S. R.

2016-12-01

Monterey Canyon, offshore central California, incises the shelf from near the shoreline to 30 km seaward where axial water depths approach 2,000 m. It is one of the world's most studied submarine canyons, yet debate continues concerning its age, formation, and associated geologic hazards. To address these issues, the USGS, with partial support from the California Seafloor Mapping Program, collected hundreds of kilometers of high-resolution, mini-sparker, single-channel (2009 and 2011 surveys) and multichannel (2015 survey) seismic-reflection profiles near the canyon head. The seismic data were combined with multibeam bathymetry to generate a geologic map of the proximal canyon, which delineates numerous faults and compound submarine landslide headwall scarps (covering up to 4 km2) along canyon walls. Seismic-reflection data reveal a massive ( 100 km2 lateral extent) paleochannel cut-and-fill complex underlying the proximal canyon. These subsurface cut-and-fill deposits span both sides of the relatively narrow modern canyon head, crop out in canyon walls, and incise into Purisima Formation (late Miocene and Pliocene) bedrock to depths of up to 0.3 s two-way travel time ( 240 m) below the modern shelf. We propose that the paleochannel complex represents previous locations of a migrating canyon head, and attribute its origin to multiple alternating cycles of fluvial and submarine canyon erosion and deposition linked to fluctuating sea levels. Thus, the canyon head imaged in modern bathymetry is a relatively young feature, perhaps forming in the last 20,000 years of sea-level rise. The paleocanyon deposits are significantly less consolidated than bedrock in deeper canyon walls, and therefore, are probably more prone to submarine landsliding. Nearby mapped faults occur within the active, distributed, San Andreas fault system, and earthquake-generated strong ground motions are likely triggers for past and future submarine landslides and potential associated tsunamis.

Westernmost Grand Canyon incision: Testing thermochronometric resolution

NASA Astrophysics Data System (ADS)

Fox, M.; Tripathy-Lang, A.; Shuster, D. L.; Winn, C.; Karlstrom, K.; Kelley, S.

2017-09-01

The timing of carving of Grand Canyon has been debated for over 100 years with competing endmember hypotheses advocating for either a 70 Ma ("old") or <6 Ma ("young") Grand Canyon. Several geological constraints appear to support a "young" canyon model, but thermochronometric measures of cooling history and corresponding estimates of landscape evolution have been in debate. In particular, 4He/3He thermochronometric data record the distribution of radiogenic 4He (from the 238U, 235U and 232Th decay series) within an individual apatite crystal and thus are highly sensitive to the thermal history corresponding to landscape evolution. However, there are several complicating factors that make interpreting such data challenging in geologic scenarios involving reheating. Here, we analyze new data that provide measures of the cooling of basement rocks at the base of westernmost Grand Canyon, and use these data as a testbed for exploring the resolving power and limitations of 4He/3He data in general. We explore a range of thermal histories and find that these data are most consistent with a "young" Grand Canyon. A problem with the recovered thermal history, however, is that burial temperatures are under predicted based on sedimentological evidence. A solution to this problem is to increase the resistance of alpha recoil damage to annealing, thus modifying He diffusion kinetics, allowing for higher temperatures throughout the thermal history. This limitation in quantifying radiation damage (and hence crystal retentivity) introduces non-uniqueness to interpreting time-temperature paths in rocks that resided in the apatite helium partial retention zone for long durations. Another source of non-uniqueness, is due to unknown U and Th distributions within crystals. We show that for highly zoned with a decrease in effective U of 20 ppm over the outer 80% of the radius of the crystal, the 4He/3He data could be consistent with an "old" canyon model. To reduce this non-uniqueness, we

Deep-Water Coral Diversity and Habitat Associations: Differences among Northeast Atlantic Submarine Canyons

NASA Astrophysics Data System (ADS)

Shank, T. M.

2016-02-01

From 2012 to 2015, annual seafloor surveys using the towed camera TowCam were used to characterize benthic ecosystems and habitats to groundtruth recently developed habitat suitability models that predict deep-sea coral locations in northwest Atlantic canyons. Faunal distribution, abundance, and habitat data were obtained from more than 90 towed camera surveys in 21 canyons, specifically Tom's, Hendrickson, Veatch, Gilbert, Ryan, Powell, Munson, Accomac, Leonard, Washington, Wilmington, Lindenkohl, Clipper, Sharpshooter, Welker, Dogbody, Chebacco, Heel Tapper, File Bottom, Carteret, and Spencer Canyons, as well as unnamed minor canyons and inter-canyon areas. We also investigated additional canyons including Block, Alvin, Atlantis, Welker, Heezen, Phoenix, McMaster, Nantucket, and two minor canyons and two intercanyon areas through high-definition ROV image surveys from the NOAA CANEX 2013 and 2014 expeditions. Significant differences in species composition and distribution correlated with specific habitat types, depth, and individual canyons. High abundances and diversity of scleractinians, antipatharians, octocorals and sponges were highly correlated with habitat substrates, includingvertical canyon walls, margins, sediments, cobbles, boulders, and coral rubble habitat. Significant differences in species composition among canyons were observed across similar depths suggesting that many canyons may have their own biological and geological signature. Locating and defining the composition and distribution of vulnerable coral ecosystems in canyons in concert with validating predictive species distribution modeling has resulted in the regional management and conservation recommendations of these living resources and the largest proposed Marine Protected Area in North American waters.

Lava Flows in the Grand Canyon

NASA Technical Reports Server (NTRS)

2003-01-01

Over vast expanses of time, natural processes like floods and volcanoes deposit layers of rock on the Earth's surface. To delve down through layers of rock is to explore our planet's history. Sometimes rock layers are exposed through human activity, such as drilling or excavation. Other times, rivers carve through the rock. One of the best, and most well-known, examples of a river exposing ancient rocks is Colorado River in Arizona's Grand Canyon. What fewer people know is that the Grand Canyon also has a history of relatively recent (on geologic time scales) volcanism. The evidence--hardened lava--spills down the canyon walls all the way to the river. On June 22, 2003, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the Grand Canyon, near 36.2 degrees north latitude and 113.2 degrees west longitude. ASTER detects light visible to human eyes as well as 'invisible' infrared light. Because different minerals reflect different portions of the light spectrum, ASTER can see varying mineral compositions of the rocks it observes, as well as detecting vegetation. In this three-dimensional visualization, lava fields appear brownish gray, darker than the layers of limestone, sandstone and other rock in the canyon. Vegetation appears green, and sparsely vegetated areas appear mustard. Water in the Colorado River is blue-purple. Geologists estimate that between 1.8 million and 400,000 years ago, lava flows actually dammed the Colorado River more than a dozen times. Some of the lava dams were as high as 600 meters (about 1,969 feet), forming immense reservoirs. Over time, enough water and sediment built up to push the river flow over the tops of these dams and eventually erode them away. Today, remnants of these lava dams remain throughout the area, along with the much older rock layers they cover. Among the most well known examples of these 'frozen' lava cascades is Lava Falls, which spills down to the

Exposure pathways and biological receptors: baseline data for the canyon uranium mine, Coconino County, Arizona

USGS Publications Warehouse

Hinck, Jo E.; Linder, Greg L.; Darrah, Abigail J.; Drost, Charles A.; Duniway, Michael C.; Johnson, Matthew J.; Méndez-Harclerode, Francisca M.; Nowak, Erika M.; Valdez, Ernest W.; van Riper, Charles; Wolff, S.W.

2014-01-01

Recent restrictions on uranium mining within the Grand Canyon watershed have drawn attention to scientific data gaps in evaluating the possible effects of ore extraction to human populations as well as wildlife communities in the area. Tissue contaminant concentrations, one of the most basic data requirements to determine exposure, are not available for biota from any historical or active uranium mines in the region. The Canyon Uranium Mine is under development, providing a unique opportunity to characterize concentrations of uranium and other trace elements, as well as radiation levels in biota, found in the vicinity of the mine before ore extraction begins. Our study objectives were to identify contaminants of potential concern and critical contaminant exposure pathways for ecological receptors; conduct biological surveys to understand the local food web and refine the list of target species (ecological receptors) for contaminant analysis; and collect target species for contaminant analysis prior to the initiation of active mining. Contaminants of potential concern were identified as arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, thallium, uranium, and zinc for chemical toxicity and uranium and associated radionuclides for radiation. The conceptual exposure model identified ingestion, inhalation, absorption, and dietary transfer (bioaccumulation or bioconcentration) as critical contaminant exposure pathways. The biological survey of plants, invertebrates, amphibians, reptiles, birds, and small mammals is the first to document and provide ecological information on .200 species in and around the mine site; this study also provides critical baseline information about the local food web. Most of the species documented at the mine are common to ponderosa pine Pinus ponderosa and pinyon–juniper Pinus–Juniperus spp. forests in northern Arizona and are not considered to have special conservation status by state or federal agencies; exceptions

The influence of the San Gregorio fault on the morphology of Monterey Canyon

USGS Publications Warehouse

McHugh, C.M.G.; Ryan, William B. F.; Eittreim, S.; Donald, Reed

1998-01-01

A side-scan sonar survey was conducted of Monterey Canyon and the San Gregorio fault zone, off shore of Monterey Bay. The acoustic character and morphology of the sonar images, enhanced by SeaBeam bathymetry, show the path of the San Gregorio fault zone across the shelf, upper slope, and Monterey Canyon. High backscatter linear features a few kilometers long and 100 to 200 m wide delineate the sea-floor expression of the fault zone on the shelf. Previous studies have shown that brachiopod pavements and carbonate crusts are the source of the lineations backscatter. In Monterey Canyon, the fault zone occurs where the path of the canyon makes a sharp bend from WNW to SSW (1800 m). Here, the fault is marked by NW-SE-trending, high reflectivity lineations that cross the canyon floor between 1850 m and 1900 m. The lineations can be traced to ridges on the northwestern canyon wall where they have ~ 15 m of relief. Above the low-relief ridges, bowl-shaped features have been excavated on the canyon wall contributing to the widening of the canyon. We suggest that shear along the San Gregorio fault has led to the formation of the low-relief ridges near the canyon wall and that carbonate crusts, as along the shelf, may be the source of the high backscatter features on the canyon floor. The path of the fault zone across the upper slope is marked by elongated tributary canyons with high backscatter floors and 'U'-shaped cross-sectional profiles. Linear features and stepped scarps suggestive of recent crustal movement and mass-wasting, occur on the walls and floors of these canyons. Three magnitude-4 earthquakes have occurred within the last 30 years in the vicinity of the canyons that may have contributed to the observed features. As shown by others, motion along the fault zone has juxtaposed diverse lithologies that outcrop on the canyon walls. Gully morphology and the canyon's drainage patterns have been influenced by the substrate into which the gullies have formed.

Is Canyon Width a Diagnostic Indicator of the Discharge of Megafloods on Earth and Mars?

NASA Astrophysics Data System (ADS)

Lapotre, M. G.; Lamb, M. P.

2013-12-01

On Earth, large floods have carved steep-walled and amphitheater-headed canyons from the Pleistocene (e.g. Box Canyon, ID) through the Holocene (e.g. Asbyrgi Canyon, Iceland), to historic times (e.g. Canyon Lake Gorge, TX). The geologic record on Mars suggests that similar floods have carved canyons by waterfall retreat about 3.5 billion years ago, when the red planet was wetter and possibly warmer. We currently lack robust paleo-hydraulic tools to reconstruct the discharge of ancient floods, especially on Mars where sediment sizes are obscured from observation. To address this issue, we hypothesize that the width of canyon escarpment is controlled by the hydraulics of the canyon-carving flood due to focusing of the flood into the canyon head. We compiled field data from multiple canyons and floods on Earth and Mars and show that there is a correlation between estimated flood discharge and canyon headwall width. To explore what sets this relationship, we identified five important parameters using dimensional analysis: the Froude number, the ratio of backwater length to canyon length, the ratio of backwater length to flood width, the ratio of canyon width to flood width, and the topographic slope upstream of the canyon. We used the hydraulic numerical modeling suite ANUGA to simulate overland flow over different canyon geometries and flood parameters to systematically explore the relative bed shear stresses along the canyon rim as a metric for flow focusing. Results show that canyons that exceed a certain length, scaling with the hydraulic backwater length, have shear stresses at their heads that are significantly higher than near the canyon mouth. Shear stresses along the rim of the canyon sidewalls are limited, in comparison to stresses along the canyon head, when the flood width is of the order of the backwater length. Flow focusing only occurs for subcritical flow. Together, these results suggest that canyons may only grow from a perturbation that is large

Optimizing Street Canyon Orientation for Rajarhat Newtown, Kolkata, India

NASA Astrophysics Data System (ADS)

De, Bhaskar; Mukherjee, Mahua

2017-12-01

Air temperature in urban street canyons is increased due to the morphed urban geometry, increased surface area, decreased long wave radiation and evapo-transpiration, different thermo-physical properties of surface materials and anthropogenic heat which results in thermal discomfort. Outdoor thermal stress can be mitigated substantially by properly orienting the canyons. It is crucial for the urban planners and designers to orient street canyons optimally considering variable local climatic context. It is important especially for cities in warm humid climatic context as these cities receive higher insolation with higher relative humidity and low level macro wind flow. This paper examines influence of canyon orientation on outdoor thermal comfort and proposes the optimum canyon orientation for the Rajarhat Newtown, Kolkata - a city in warm humid climate zone. Different scenarios are generated with different orientations. Change in air temperature, wind speed, Mean Radiant Temperature (MRT) and Physiological Equivalent Temperature (PET) of different scenarios are compared to find out the optimum orientation by parametric simulation in ENVI_met. Analysing the simulation results it is observed that orientation angle between 30°-60° to north performs the best for the study area of the Rajarhat Newtown. The findings of this research will be helpful for the planners to orient the street canyons optimally for future development and extension of the Rajarhat Newtown, Kolkata.

Giant submarine canyons: Is size any clue to their importance in the rock record?

USGS Publications Warehouse

Normark, William R.; Carlson, Paul R.

2003-01-01

Submarine canyons are the most important conduits for funneling sediment from continents to oceans. Submarine canyons, however, are zones of sediment bypassing, and little sediment accumulates in the canyon until it ceases to be an active conduit. To understand the potential importance in the rock record of any given submarine canyon, it is necessary to understand sediment-transport processes in, as well as knowledge of, deep-sea turbidite and related deposits that moved through the canyons. There is no straightforward correlation between the final volume of the sedimentary deposits and size of the associated submarine canyons. Comparison of selected modern submarine canyons together with their deposits emphasizes the wide range of scale differences between canyons and their impact on the rock record.Three of the largest submarine canyons in the world are incised into the Beringian (North American) margin of the Bering Sea. Zhemchug Canyon has the largest cross-section at the shelf break and greatest volume of incision of slope and shelf. The Bering Canyon, which is farther south in the Bering Sea, is first in length and total area. In contrast, the largest submarine fans-e.g., Bengal, Indus, and Amazon-have substantially smaller, delta-front submarine canyons that feed them; their submarine drainage areas are one-third to less than one-tenth the area of Bering Canyon. some very large deep-sea channels and tubidite deposits are not even associated with a significant submarine canyon; examples include Horizon Channel in the northeast Pacific and Laurentian Fan Valley in the North Atlantic. Available data suggest that the size of turbidity currents (as determined by volume of sediment transported to the basins) is also not a reliable indicator of submarine canyon size.

Canyon Sand, Sonora basin: foam fracs hoped to slow production decline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wash, R.

Rapid decline rates (60 to 80%/yr) in wells in the Conger-Penn field in Sterling County, Texas, have prompted Dorchester Exploration Corp. to try its first foam frac jobs on the Canyon Sand formation at 7000 to 7500 ft. Since Nov., the fracs have been performed on 3 wells: the Terry No. 31-4, the Terry No. 18-4, and the R.T. Foster No 11-4 in the southern portion of the field. Although it is still too early to tell whether the dramatic production drops have been arrested, personnel involved in the program seem pleased with the foam technique. The purpose behind Dorchester'smore » experimentation in this region is to decrease the amount of fluid that conventional frac jobs leave in the tight sand formation. The advantages of using foam fracs in this area are discussed.« less

Currents in monterey submarine canyon

USGS Publications Warehouse

Xu, J. P.; Noble, M.A.

2009-01-01

Flow fields of mean, subtidal, and tidal frequencies between 250 and 3300 m water depths in Monterey Submarine Canyon are examined using current measurements obtained in three yearlong field experiments. Spatial variations in flow fields are mainly controlled by the topography (shape and width) of the canyon. The mean currents flow upcanyon in the offshore reaches (>1000 m) and downcanyon in the shallow reaches (100-m amplitude isotherm oscillations and associated high-speed rectilinear currents. The 15-day spring-neap cycle and a ???3-day??? band are the two prominent frequencies in subtidal flow field. Neither of them seems directly correlated with the spring-neap cycle of the sea level.

Geologic map of the Cameron 30' x 60' quadrangle, Coconino County, northern Arizona

USGS Publications Warehouse

Billingsley, George H.; Priest, Susan S.; Felger, Tracey J.

2007-01-01

This geologic map is the result of a cooperative effort of the U.S. Geological Survey and the National Park Service in collaboration with the Navajo Nation and the Hopi Tribe to provide regional geologic information for resource management officials of the National Park Service, U.S. Forest Service, Navajo Indian Reservation (herein the Navajo Nation), the Hopi Tribe, and for visitor information services at Grand Canyon National Park, Arizona as well as private enterprises that have lands within the area. The Cameron 30’ x 60’ quadrangle encompasses approximately 5,018 km2 (1,960 mi2) within Coconino County, northern Arizona and is bounded by longitude 111° to 112° W., and latitude 35°30’ to 36° N. The map area is within the southern Colorado Plateaus geologic province (herein Colorado Plateau). The map area is locally subdivided into six physiographic areas: the Grand Canyon (including the Little Colorado River Gorge), Coconino Plateau, Marble Plateau, Little Colorado River Valley, Moenkopi Plateau, and the San Francisco Volcanic Field as defined by Billingsley and others, 1997 (fig. 1). Elevations range from about 2,274 m (7,460 ft) at the south rim of Grand Canyon along State Highway 64 to about 994 m (3,260 ft) in the Grand Canyon, northeast quarter of the map area.The Cameron quadrangle is one of the few remaining areas near the Grand Canyon where uniform geologic mapping was needed for geologic connectivity of the regional geologic framework that will be useful to federal, state, and private land resource managers who direct environmental and land management programs such as range management, biological studies, flood control, and water resource investigations. The geologic information presented will support future and ongoing local geologic investigations and associated scientific studies of all disciplines within the Cameron quadrangle area.

Canyon formation constraints on the discharge of catastrophic outburst floods of Earth and Mars

NASA Astrophysics Data System (ADS)

Lapotre, Mathieu G. A.; Lamb, Michael P.; Williams, Rebecca M. E.

2016-07-01

Catastrophic outburst floods carved amphitheater-headed canyons on Earth and Mars, and the steep headwalls of these canyons suggest that some formed by upstream headwall propagation through waterfall erosion processes. Because topography evolves in concert with water flow during canyon erosion, we suggest that bedrock canyon morphology preserves hydraulic information about canyon-forming floods. In particular, we propose that for a canyon to form with a roughly uniform width by upstream headwall retreat, erosion must occur around the canyon head, but not along the sidewalls, such that canyon width is related to flood discharge. We develop a new theory for bedrock canyon formation by megafloods based on flow convergence of large outburst floods toward a horseshoe-shaped waterfall. The model is developed for waterfall erosion by rock toppling, a candidate erosion mechanism in well fractured rock, like columnar basalt. We apply the model to 14 terrestrial (Channeled Scablands, Washington; Snake River Plain, Idaho; and Ásbyrgi canyon, Iceland) and nine Martian (near Ares Vallis and Echus Chasma) bedrock canyons and show that predicted flood discharges are nearly 3 orders of magnitude less than previously estimated, and predicted flood durations are longer than previously estimated, from less than a day to a few months. Results also show a positive correlation between flood discharge per unit width and canyon width, which supports our hypothesis that canyon width is set in part by flood discharge. Despite lower discharges than previously estimated, the flood volumes remain large enough for individual outburst floods to have perturbed the global hydrology of Mars.

California State Waters Map Series--Hueneme Canyon and vicinity, California

USGS Publications Warehouse

Johnson, Samuel Y.; Dartnell, Peter; Cochrane, Guy R.; Golden, Nadine E.; Phillips, Eleyne L.; Ritchie, Andrew C.; Kvitek, Rikk G.; Greene, H. Gary; Krigsman, Lisa M.; Endris, Charles A.; Clahan, Kevin B.; Sliter, Ray W.; Wong, Florence L.; Yoklavich, Mary M.; Normark, William R.

2012-01-01

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California's State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow (to about 100 m) subsurface geology. The Hueneme Canyon and vicinity map area lies within the eastern Santa Barbara Channel region of the Southern California Bight. The area is part of the Western Transverse Ranges geologic province, which is north of the California Continental Borderland. Significant clockwise rotation - at least 90° - since the early Miocene has been proposed for the Western Transverse Ranges, and the region is presently undergoing north-south shortening. This geologically complex region forms a major biogeographic transition zone, separating the cold-temperate Oregonian province north of Point Conception from the warm-temperate California province to the south. The map area, which is offshore of the Oxnard plain and west of and along the trend of the south flank of the Santa Monica Mountains, lies at the east end of the Santa Barbara littoral cell, characterized by west-to-east littoral transport of sediment derived mainly from coastal watersheds. The Hueneme Canyon and vicinity map area in California's State Waters is characterized by two major physiographic features: (1) the nearshore continental shelf, and (2) the Hueneme and Mugu Submarine Canyon system, which, in the map area, includes Hueneme Canyon and parts

California State Waters Map Series—Monterey Canyon and vicinity, California

USGS Publications Warehouse

Dartnell, Peter; Maier, Katherine L.; Erdey, Mercedes D.; Dieter, Bryan E.; Golden, Nadine E.; Johnson, Samuel Y.; Hartwell, Stephen R.; Cochrane, Guy R.; Ritchie, Andrew C.; Finlayson, David P.; Kvitek, Rikk G.; Sliter, Ray W.; Greene, H. Gary; Davenport, Clifton W.; Endris, Charles A.; Krigsman, Lisa M.; Dartnell, Peter; Cochran, Susan A.

2016-06-10

IntroductionIn 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath bathymetry data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology.The Monterey Canyon and Vicinity map area lies within Monterey Bay in central California. Monterey Bay is one of the largest embayments along the west coast of the United States, spanning 36 km from its northern to southern tips (in Santa Cruz and Monterey, respectively) and 20 km along its central axis. Not only does it contain one of the broadest sections of continental shelf along California’s coast, it also contains Monterey Canyon, one of the largest and deepest submarine canyons in the world. Note that the California’s State Waters limit extends farther offshore between Santa Cruz and Monterey so that it encompasses all of Monterey Bay.The coastal area within the map area is lightly populated. The community of Moss Landing (population, 204) hosts the largest commercial fishing fleet in Monterey Bay in its harbor. The map area also includes parts of the cities of Marina (population, about 20,000) and Castroville (population, about 6,500). Fertile lowlands of the Salinas River and Pajaro River valleys largely occupy the inland part of the map area, and land use is primarily agricultural.The offshore part of the map area lies completely within the Monterey Bay National Marine Sanctuary. The

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Grand Canyon National Park. 7.4 Section 7.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.4 Grand Canyon National Park. (a) Commercial...

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Grand Canyon National Park. 7.4 Section 7.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.4 Grand Canyon National Park. (a) Commercial...

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Grand Canyon National Park. 7.4 Section 7.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.4 Grand Canyon National Park. (a) Commercial...

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Grand Canyon National Park. 7.4 Section 7.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.4 Grand Canyon National Park. (a) Commercial...

B-Plant Canyon Ventilation Control System Description

DOE Office of Scientific and Technical Information (OSTI.GOV)

MCDANIEL, K.S.

1999-08-31

Project W-059 installed a new B Plant Canyon Ventilation System. Monitoring and control of the system is implemented by the Canyon Ventilation Control System (CVCS). This document describes the CVCS system components which include a Programmable Logic Controller (PLC) coupled with an Operator Interface Unit (OIU) and application software. This document also includes an Alarm Index specifying the setpoints and technical basis for system analog and digital alarms.

Measuring currents in submarine canyons: technological and scientific progress in the past 30 years

USGS Publications Warehouse

Xu, J. P.

2011-01-01

The development and application of acoustic and optical technologies and of accurate positioning systems in the past 30 years have opened new frontiers in the submarine canyon research communities. This paper reviews several key advancements in both technology and science in the field of currents in submarine canyons since the1979 publication of Currents in Submarine Canyons and Other Sea Valleys by Francis Shepard and colleagues. Precise placements of high-resolution, high-frequency instruments have not only allowed researchers to collect new data that are essential for advancing and generalizing theories governing the canyon currents, but have also revealed new natural phenomena that challenge the understandings of the theorists and experimenters in their predictions of submarine canyon flow fields. Baroclinic motions at tidal frequencies, found to be intensified both up canyon and toward the canyon floor, dominate the flow field and control the sediment transport processes in submarine canyons. Turbidity currents are found to frequently occur in active submarine canyons such as Monterey Canyon. These turbidity currents have maximum speeds of nearly 200 cm/s, much smaller than the speeds of turbidity currents in geological time, but still very destructive. In addition to traditional Eulerian measurements, Lagrangian flow data are essential in quantifying water and sediment transport in submarine canyons. A concerted experiment with multiple monitoring stations along the canyon axis and on nearby shelves is required to characterize the storm-trigger mechanism for turbidity currents.

Red Rock Canyon National Conservation Area Transportation Feasibility Study

DOT National Transportation Integrated Search

2012-07-31

Red Rock Canyon National Conservation Area is a popular Bureau of Land Management natural area located near Las Vegas, Nevada. Red Rock Canyon experiences heavy congestion on its Scenic Drive and associated parking areas, due to high volumes of visit...

Environmental analysis of Lower Pueblo/Lower Los Alamos Canyon, Los Alamos, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.

1994-12-01

The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, Pueblo Canyon, and Los Alamos Canyon found residual contamination at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons all the way to the Rio Grande. The largest reservoir of residual radioactivity is in lower Pueblo Canyon, which is on DOE property. However, residual radioactivity does not exceed proposed cleanup criteria in either lower Pueblo or lower Los Alamos Canyons. The three alternatives proposed are (1) to take no action, (2) to construct a sediment trap in lowermore » Pueblo Canyon to prevent further transport of residual radioactivity onto San Ildefonso Indian Pueblo land, and (3) to clean the residual radioactivity from the canyon system. Alternative 2, to cleanup the canyon system, is rejected as a viable alternative. Thousands of truckloads of sediment would have to be removed and disposed of, and this effort is unwarranted by the low levels of contamination present. Residual radioactivity levels, under either present conditions or projected future conditions, will not result in significant radiation doses to persons exposed. Modeling efforts show that future transport activity will not result in any residual radioactivity concentrations higher than those already existing. Thus, although construction of a sediment trap in lower Pueblo Canyon is a viable alternative, this effort also is unwarranted, and the no-action alternative is the preferred alternative.« less

Coal Rank and Stratigraphy of Pennsylvanian Coal and Coaly Shale Samples, Young County, North-Central Texas

USGS Publications Warehouse

Guevara, Edgar H.; Breton, Caroline; Hackley, Paul C.

2007-01-01

Vitrinite reflectance measurements were made to determine the rank of selected subsurface coal and coaly shale samples from Young County, north-central Texas, for the National Coal Resources Database System State Cooperative Program conducted by the Bureau of Economic Geology at The University of Texas at Austin. This research is the continuation of a pilot study that began in adjacent Archer County, and forms part of a larger investigation of the coalbed methane resource potential of Pennsylvanian coals in north-central Texas. A total of 57 samples of coal and coaly shale fragments were hand-picked from drill cuttings from depths of about 2,000 ft in five wells, and Ro determinations were made on an initial 10-sample subset. Electric-log correlation of the sampled wells indicates that the collected samples represent coal and coaly shale layers in the Strawn (Pennsylvanian), Canyon (Pennsylvanian), and Cisco (Pennsylvanian-Permian) Groups. Coal rank in the initial sample subset ranges from lignite (Ro=0.39), in a sample from the Cisco Group at a depth of 310 to 320 ft, to high volatile bituminous A coal (Ro=0.91) in a sample from the lower part of the Canyon Group at a depth of 2,030 to 2,040 ft.

Morphology of Submarine Canyons in the Palomares Margin (East of Alboran Sea, western Mediterranean)

NASA Astrophysics Data System (ADS)

Perez-Hernandez, S.; Comas, M. C.; Escutia, C.

2009-04-01

Morphological analysis on the Palomares Margin has been done using high-resolution swath bathymetry data collected during the MARSIBAL-06 (2006) cruise on board of the R/V BIO Hespérides. Complemented with data from GEBCO 2000 and Ifremer (Medimap Group, 2007) the data-set provides the first complete bathymetric mosaic of the Palomares Margin. The bathymetric mosaic allows to study the physiographic provinces of the Palomares Margin and to conduct, for the first time, a detailed morphological analysis of the two main sediment-transfer conduits: the Gata and the Alias-Almanzora Canyons. The Gata Canyon extends for 64km from the outer shelf to the base of the slope with a general W-E direction. A tributary system of canyons originates at the shelf break and continues on the slope until they merge at 1230m water depth. The walls of the canyons are characterized by repeated slides. Perpendicular profiles to the Canyon pathway reveal gentle transversal "V" asymmetrical shapes with a marked axial incision on the canyon floor (highs between 65 to 103m in the southern flank, and between 30-90m in the northern flank ). The transition from an erosional canyon to a deposition channel is located at 2100m water depth, and is characterized by trapezoidal shapes on transversal profiles accompanied of lower relieves (40-65m). At the mouth of the canyon-channel system no sedimentary lobes are observed. The Alias-Almanzora canyon (73km long and preferential direction W-E) is located North of the Gata Canyon and extends from the continental shelf to the base of the slope. A tributary system to the Alias- Almanzora canyon-head locates less than 150m from the coast, facing a fluvial drainage system onland. Proximal tributary canyons and gullies feed the main canyon until it merges in the continental slope at 1516m water depth. The tributary system exhibits a marked "V" shape in transverse profiles and marked axial incisions. Down slope, transversal profiles have trapezoidal shapes

Does littoral sand bypass the head of Mugu Submarine Canyon? - a modeling study

USGS Publications Warehouse

Xu, Jingping; Elias, Edwin; Kinsman, Nicole; Wang, Ping; Rosati, Julie D.; Roberts, Tiffany M.

2011-01-01

A newly developed sand-tracer code for the process-based model Delft3D (Deltares, The Netherlands) was used to simulate the littoral transport near the head of the Mugu Submarine Canyon in California, USA. For westerly swells, which account for more than 90% of the wave conditions in the region, the sand tracers in the downcoast littoral drift were unable to bypass the canyon head. A flow convergence near the upcoast rim of the canyon intercepts the tracers and moves them either offshore onto the shelf just west of the canyon rim (low wave height conditions) or into the canyon head (storm wave conditions). This finding supports the notion that Mugu Canyon is the true terminus of the Santa Barbara Littoral Cell.

Influence of San Gabriel submarine canyon on narrow-shelf sediment dynamics, southern California

USGS Publications Warehouse

Karl, Herman A.

1980-01-01

A conceptual model attributes the PTC to modification of shelf circulation patterns by San Gabriel Canyon. Surface waves diverge over the canyon head resulting in differential wave set up at the shore face. This forces back turbid nearshore water for a distance of a few kilometers toward the canyon. At some point on the shelf, seaward nearshore flow overlaps offshore currents generated or modified by internal waves focused onto the shelf by the canyon and/or turbulent eddies produced by flow separation in currents moving across the canyon axis. At times, these subtle processes overprint tidal and wind-driven currents and thereby create the PTC. The model suggests that canyons heading several kilometers from shore can have a regulatory effect on narrow-shelf sediment dynamics.

Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin

USGS Publications Warehouse

Obelcz, Jeffrey; Brothers, Daniel S.; Chaytor, Jason D.; ten Brink, Uri S.; Ross, Steve W.; Brooke, Sandra

2013-01-01

Shelf-sourced submarine canyons are common features of continental margins and are fundamental to deep-sea sedimentary systems. Despite their geomorphic and geologic significance, relatively few passive margin shelf-breaching canyons worldwide have been mapped using modern geophysical methods. Between 2007 and 2012 a series of geophysical surveys was conducted across four major canyons of the US Mid-Atlantic margin: Wilmington, Baltimore, Washington, and Norfolk canyons. More than 5700 km2 of high-resolution multibeam bathymetry and 890 line-km of sub-bottom CHIRP profiles were collected along the outer shelf and uppermost slope (depths of 80-1200 m). The data allowed us to compare and contrast the fine-scale morphology of each canyon system. The canyons have marked differences in the morphology and orientation of canyon heads, steepness and density of sidewall gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles for Washington, Baltimore and Wilmington canyons have linear shapes, and each canyon thalweg exhibits morphological evidence for recent, relatively small-scale sediment transport. For example, Washington Canyon displays extremely steep wall gradients and contains ~100 m wide, 5–10 m deep, v-shaped incisions down the canyon axis, suggesting modern or recent sediment transport. In contrast, the convex axial thalweg profile, the absence of thalweg incision, and evidence for sediment infilling at the canyon head, suggest that depositional processes strongly influence Norfolk Canyon during the current sea-level high-stand. The north walls of Wilmington, Washington and Norfolk canyons are steeper than the south walls due to differential erosion, though the underlying cause for this asymmetry is not clear. Furthermore, we speculate that most of the geomorphic features observed within the canyons (e.g., terraces, tributary canyons, gullies, and hanging valleys) were formed during the Pleistocene, and show only

Science Activities Associated with Proposed 2008 High-Flow Experiment at Glen Canyon Dam

USGS Publications Warehouse

Hamill, John

2008-01-01

Grand Canyon National Park lies approximately 15 miles downriver from Glen Canyon Dam, which was built on the Colorado River just south of the Arizona-Utah border. Because the dam stops most sediment moving downstream, its presence has resulted in erosion and shrinkage of river sandbars in Grand Canyon. Fewer and smaller sandbars mean smaller camping beaches for visitors to use, continued erosion of cultural sites, and possibly less habitat for native fish, including the endangered humpback chub. In an effort to restore sandbars and related habitat and to comply with its responsibilities under the Grand Canyon Protection Act, the Department of the Interior has proposed a high-flow release of water from Glen Canyon Dam in March 2008. The U.S. Geological Survey?s (USGS) Grand Canyon Monitoring and Research Center is responsible for coordinating research associated with the proposed experiment. The proposed studies are designed to evaluate the feasibility of using such high flows to improve a range of Grand Canyon resources.

Hydrogeology of Cibola County, New Mexico

USGS Publications Warehouse

Baldwin, J.A.; Rankin, D.R.

1995-01-01

The hydrogeology of Cibola County, New Mexico, was evaluated to determine the occurrence, availability, and quality of ground-water resources. Rocks of Precambrian through Quaternary age are present in Cibola County. Most rocks are sedimentary in origin except for Precambrian igneous and metamorphic rocks exposed in the Zuni Uplift and Tertiary and Quaternary basalts in northern and central parts of the county. The most productive aquifers in the county include (youngest to oldest) Quaternary deposits, sandstones in the Mesaverde Group, the Dakota-Zuni-Bluff aquifer, the Westwater Canyon aquifer, the Todilto- Entrada aquifer, sandstone beds in the Chinle Formation, and the San Andres-Glorieta aquifer. Unconsolidated sand, silt, and gravel form a mantle ranging from a few inches to 150 to 200 feet over much of the bedrock in Cibola County. Well yields range from 5 to 1,110 gallons per minute. Dissolved-solids concentrations of ground water range from 200 to more than 5,200 milligrams per liter. Calcium, magnesium, bicarbonate, and sulfate are the predominant ions in ground water in alluvial material. The Mesaverde Group mainly occurs in three areas of the county. Well yields range from less than 1 to 12 gallons per minute. The predominant ions in water from wells in the Mesaverde Group are calcium, sodium, and bicarbonate. The transition from calcium-predominant to sodium-predominant water in the southwestern part of the county likely is a result of ion exchange. Wells completed in the Dakota-Zuni-Bluff aquifer yield from 1 to 30 gallons per minute. Dissolved-solids concentrations range from 220 to 2,000 milligrams per liter in water from 34 wells in the western part of the county. Predominant ions in the ground water include calcium, sodium, sulfate, and bicarbonate. Calcium predominates in areas where the aquifer is exposed at the surface or is overlain with alluvium. Sandstones in the Chinle Formation yield from 10 to 300 gallons per minute to wells in the Grants

Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Canyon Fire, Los Angeles County, Southern California

USGS Publications Warehouse

Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

2007-01-01

INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Canyon Fire in Los Angeles County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

Composition, Distribution and Abundance of Anthropogenic Marine Debris in Northwest Atlantic Submarine Canyons

NASA Astrophysics Data System (ADS)

Heyl, T. P.; Nizinski, M. S.; Kinlan, B. P.; Shank, T. M.

2016-02-01

Submarine canyons are important productive habitats in the deep-sea, as well as downslope conduits for transporting sediment and organic material that enhances local and regional species diversity, including species and ecosystems vulnerable to anthropogenic activities. In 2012 and 2013, we documented and characterized deep-sea coral and sponge ecosystems in virtually unexplored northeast and mid-Atlantic canyons using WHOI's TowCam towed imaging system on the FSV Bigelow. Specifically, thirty-eight digital image TowCam surveys were completed in 10 canyons, with more than 91,000 images documenting not only deep-sea coral and sponge ecosystems and habitat features, but also anthropogenic debris. Canyons surveyed cover most of the latitudinal range of the northeast US region and include Toms Canyon complex, Ryan, Veatch, Gilbert, Powell, and Munson canyons. Each of these canyon hosted debris across depths of 550 to 2100m, consisting mostly of fisheries equipment, including fishing lines, traps, and nets. Potentially-land-based debris (e.g., plastic bags and magazines) was also present in all canyons surveyed. These substrates likely enhance colonization and often served as habitat for specific sessile and mobile species. Comparisons of debris in these canyons revealed depth-related differences, likely due to offshore extent of fishing activities, and will be compared to density and abundances of other deep-sea environments. The occurrence of anthropogenic debris on Northeast US canyon floors suggests major sources via transport ship and fishing-related activities and perhaps the rapid transport of debris through near-shore zones and entrainment in bottom currents.

Creationism in the Grand Canyon, Texas Textbooks

NASA Astrophysics Data System (ADS)

Folger, Peter

2004-01-01

AGU President Bob Dickinson, together with presidents of six other scientific societies, have written to Joseph Alston, Superintendent of Grand Canyon National Park, pointing out that a creationist book, The Grand Canyon: A Different View, is being sold in bookstores within the borders of the park as a scientific explanation about Grand Canyon geologic history. President Dickinson's 16 December letter urges that Alston clearly separate The Grand Canyon: A Different View from books and materials that discuss the legitimate scientific understanding of the origin of the Grand Canyon. The letter warns the Park Service against giving the impression that it approves of the anti-science movement known as young-Earth creationism, or that it endorses the advancement of religious tenets disguised as science. The text of the letter is on AGU's Web site http://www.agu.org/sci_soc/policy/sci_pol.html. Also, this fall, AGU sent an alert to Texas members about efforts by intelligent design creationists aimed at weakening the teaching of biological evolution in textbooks used in Texas schools. The alert pointed scientists to a letter, drafted by AGU, together with the American Institute of Physics, the American Physical Society, the Optical Society of America, and the American Astronomical Society, that urged the Texas State Board of Education to adopt textbooks that presented only accepted, peer-reviewed science and pedagogical expertise. Over 550 scientists in Texas added their names to the letter (http://www.agu.org/sci_soc/policy/texas_textbooks.pdf ), sent to the Board of Education on 1 November prior to their vote to adopt a slate of new science textbooks. The Board voted 11-5 in favor of keeping the textbooks free of changes advocated by groups supporting intelligent design creationism.

Anomalous topography on the continental shelf around Hudson Canyon

USGS Publications Warehouse

Knebel, H.J.

1979-01-01

Recent seismic-reflection data show that the topography on the Continental Shelf around Hudson Canyon is composed of a series of depressions having variable spacings (< 100 m to 2 km), depths (1-10 m), outlines, and bottom configurations that give the sea floor an anomalous "jagged" appearance in profile. The acoustic and sedimentary characteristics, the proximity to relict shores, and the areal distribution indicate that this rough topography is an erosional surface formed on Upper Pleistocene silty sands about 13,000 to 15,000 years ago by processes related to Hudson Canyon. The pronounced southward extension of the surface, in particular, may reflect a former increase in the longshore-current erosion capacity caused by the loss of sediments over the canyon. Modern erosion or nondeposition of sediments has prevented the ubiquitous sand sheet on the Middle Atlantic shelf from covering the surface. The "anomalous" topography may, in fact, be characteristic of areas near other submarine canyons that interrupt or have interrupted the longshore drift of sediments. ?? 1979.

The timing of sediment transport down Monterey Submarine Canyon, offshore California

USGS Publications Warehouse

Stevens, Thomas; Paull, Charles K.; Ussler, William III; McGann, Mary; Buylaert, Jan-Pieter; Lundsten, Eve M.

2013-01-01

While submarine canyons are the major conduits through which sediments are transported from the continents out into the deep sea, the time it takes for sediment to pass down through a submarine canyon system is poorly constrained. Here we report on the first study to couple optically stimulated luminescence (OSL) ages of quartz sand deposits and accelerator mass spectrometry 14C ages measured on benthic foraminifera to examine the timing of sediment transport through the axial channel of Monterey Submarine Canyon and Fan, offshore California. The OSL ages date the timing of sediment entry into the canyon head while the 14C ages of benthic foraminifera record the deposition of hemipelagic sediments that bound the sand horizons. We use both single-grain and small (∼2 mm area) single-aliquot regeneration approaches on vibracore samples from fining-upward sequences at various water depths to demonstrate relatively rapid, decadal-scale sand transport to at least 1.1 km depth and more variable decadal- to millennial-scale transport to a least 3.5 km depth on the fan. Significant differences between the time sand was last exposed at the canyon head (OSL age) and the timing of deposition of the sand (from 14C ages of benthic foraminifera in bracketing hemipelagic sediments) are interpreted as indicating that the sand does not pass through the entire canyon instantly in large individual events, but rather moves multiple times before emerging onto the fan. The increased spread in single-grain OSL dates with water depth provides evidence of mixing and temporary storage of sediment as it moves through the canyon system. The ages also indicate that the frequency of sediment transport events decreases with distance down the canyon channel system. The amalgamated sands near the canyon head yield OSL ages that are consistent with a sub-decadal recurrence frequency while the fining-upward sand sequences on the fan indicate that the channel is still experiencing events with a 150�

Hydraulics of outburst floods spilling over a steep-walled canyon: Implications for paleo-discharges on Mars

NASA Astrophysics Data System (ADS)

Lapotre, Mathieu; Lamb, Michael

2013-04-01

Canyons carved by outburst floods are common landforms on Earth and Mars. These canyons are generally found in fractured basalts and jointed sedimentary rocks. Flood-carved canyons commonly have steep headwalls and a roughly constant width, and are often thought to have formed from upstream headwall propagation due to waterfall erosion. Because morphology is readily available from satellite imagery, these canyons offer a unique opportunity to quantify the discharge of rare, catastrophic paleo-floods on Earth and Mars. However, mechanistic relationships that relate canyon size to flood discharge have yet to be developed. We propose that the width of a canyon headwall in fractured rock is set by the spatial distribution of erosion around the rim of the canyon, which is controlled by the distribution of shear stresses induced by the overflowing water as it is focused into the canyon head. We test this hypothesis by performing a series of numerical simulations of flood-water focusing using ANUGA Hydro, a 2D-depth averaged, fully turbulent, hydraulic numerical modeling suite allowing for Froude-number transitions. The numerical simulations were designed to explore five dimensionless variables: the aspect ratio of the canyon (length normalized by width), the canyon width to flood-water width ratio, the canyon width to normal-flow depth ratio, the Froude number, and the topographic gradient upstream of the canyon. Preliminary results show that flow focusing leads to increased shear stresses at the canyon head compared to the sides of the canyon for subcritical floods and higher canyon aspect ratios. This suggests that proto-canyons start growing from a topographic defect in all directions until they reach a critical length for the side walls to dry. Once this critical length is attained, canyons focus most of the flood waters into their heads, and propagate upstream only, maintaining roughly constant widths. Preliminary results suggest that canyon width may be used to

Partly standing internal tides in a dendritic submarine canyon observed by an ocean glider

NASA Astrophysics Data System (ADS)

Hall, Rob A.; Aslam, Tahmeena; Huvenne, Veerle A. I.

2017-08-01

An autonomous ocean glider is used to make the first direct measurements of internal tides within Whittard Canyon, a large, dendritic submarine canyon system that incises the Celtic Sea continental slope and a site of high benthic biodiversity. This is the first time a glider has been used for targeted observations of internal tides in a submarine canyon. Vertical isopycnal displacement observations at different stations fit a one-dimensional model of partly standing semidiurnal internal tides - comprised of a major, incident wave propagating up the canyon limbs and a minor wave reflected back down-canyon by steep, supercritical bathymetry near the canyon heads. The up-canyon internal tide energy flux in the primary study limb decreases from 9.2 to 2.0 kW m-1 over 28 km (a dissipation rate of 1 - 2.5 ×10-7 Wkg-1), comparable to elevated energy fluxes and internal tide driven mixing measured in other canyon systems. Within Whittard Canyon, enhanced mixing is inferred from collapsed temperature-salinity curves and weakened dissolved oxygen concentration gradients near the canyon heads. It has previously been hypothesised that internal tides impact benthic fauna through elevated near-bottom current velocities and particle resuspension. In support of this, we infer order 20 cm s-1 near-bottom current velocities in the canyon and observe high concentrations of suspended particulate matter. The glider observations are also used to estimate a 1 °C temperature range and 12 μmol kg-1 dissolved oxygen concentration range, experienced twice a day by organisms on the canyon walls, due to the presence of internal tides. This study highlights how a well-designed glider mission, incorporating a series of tide-resolving stations at key locations, can be used to understand internal tide dynamics in a region of complex topography, a sampling strategy that is applicable to continental shelves and slopes worldwide.

Status and Trends of Resources Below Glen Canyon Dam Update - 2009

USGS Publications Warehouse

Hamill, John F.

2009-01-01

The protection of resources found in Glen Canyon National Recreation Area and Grand Canyon National Park, Arizona, emerged as a significant public concern in the decades following the completion of Glen Canyon Dam in 1963. The dam, which lies about 15 miles upstream from the park, altered the Colorado River's flow, temperature, and sediment-carrying capacity, resulting over time in beach erosion, expansion of nonnative species, and losses of native fish. During the 1990s, in response to public concern, Congress and the Department of the Interior embarked on an ongoing effort to reduce and address the effects of dam operations on downstream resources. In 2005, the U.S. Geological Survey produced a comprehensive report entitled 'The State of the Colorado River Ecosystem in Grand Canyon', which documented the condition and trends of resources downstream of Glen Canyon Dam from 1991 to 2004. This fact sheet updates the 2005 report to extend its findings to include data published through April 2009 for key resources.

Space-for-time substitution and the evolution of submarine canyons in a passive, progradational margin.

NASA Astrophysics Data System (ADS)

Micallef, Aaron; Ribó, Marta; Canals, Miquel; Puig, Pere; Lastras, Galderic; Tubau, Xavier

2013-04-01

40% of submarine canyons worldwide are located in passive margins, where they constitute preferential conduits of sediment and biodiversity hotspots. Recent studies have presented evidence that submarine canyons incising passive, progradational margins can co-evolve with the adjacent continental slope during long-term margin construction. The stages of submarine canyon initiation and their development into a mature canyon-channel system are still poorly constrained, however, which is problematic when attempting to reconstruct the development of passive continental margins. In this study we analyse multibeam echosounder and seismic reflection data from the southern Ebro margin (western Mediterranean Sea) to document the stages through which a first-order gully develops into a mature, shelf-breaching canyon and, finally, into a canyon-channel system. This morphological evolution allows the application of a space-for-time substitution approach. Initial gully growth on the continental slope takes place via incision and downslope elongation, with limited upslope head retreat. Gravity flows are the main driver of canyon evolution, whereas slope failures are the main agent of erosion; they control the extent of valley widening, promote tributary development, and their influence becomes more significant with time. Breaching of the continental shelf by a canyon results in higher water/sediment loads that enhance canyon development, particularly in the upper reaches. Connection of the canyon head with a paleo-river changes evolution dynamics significantly, promoting development of a channel and formation of depositional landforms. Morphometric analyses demonstrate that canyons develop into geometrically self-similar systems that approach steady-state and higher drainage efficiency. Canyon activity in the southern Ebro margin is pulsating and enhanced during sea level lowstands. Rapid sedimentation by extension of the palaeo-Millars River into the outermost shelf and upper

Regional economic impacts of Grand Canyon river runners.

PubMed

Hjerpe, Evan E; Kim, Yeon-Su

2007-10-01

Economic impact analysis (EIA) of outdoor recreation can provide critical social information concerning the utilization of natural resources. Outdoor recreation and other non-consumptive uses of resources are viewed as environmentally friendly alternatives to extractive-type industries. While outdoor recreation can be an appropriate use of resources, it generates both beneficial and adverse socioeconomic impacts on rural communities. The authors used EIA to assess the regional economic impacts of rafting in Grand Canyon National Park. The Grand Canyon region of northern Arizona represents a rural US economy that is highly dependent upon tourism and recreational expenditures. The purpose of this research is twofold. The first is to ascertain the previously unknown regional economic impacts of Grand Canyon river runners. The second purpose is to examine attributes of these economic impacts in terms of regional multipliers, leakage, and types of employment created. Most of the literature on economic impacts of outdoor recreation has focused strictly on the positive economic impacts, failing to illuminate the coinciding adverse and constraining economic impacts. Examining the attributes of economic impacts can highlight deficiencies and constraints that limit the economic benefits of recreation and tourism. Regional expenditure information was obtained by surveying non-commercial boaters and commercial outfitters. The authors used IMPLAN input-output modeling to assess direct, indirect, and induced effects of Grand Canyon river runners. Multipliers were calculated for output, employment, and income. Over 22,000 people rafted on the Colorado River through Grand Canyon National Park in 2001, resulting in an estimated $21,100,000 of regional expenditures to the greater Grand Canyon economy. However, over 50% of all rafting-related expenditures were not captured by the regional economy and many of the jobs created by the rafting industry are lower-wage and seasonal. Policy

The Jurassic section along McElmo Canyon in southwestern Colorado

USGS Publications Warehouse

O'Sullivan, Robert B.

1997-01-01

In McElmo Canyon, Jurassic rocks are 1500-1600 ft thick. Lower Jurassic rocks of the Glen Canyon Group include (in ascending order) Wingate Sandstone, Kayenta Formation and Navajo Sandstone. Middle Jurassic rocks are represented by the San Rafael Group, which includes the Entrada Sandstone and overlying Wanakah Formation. Upper Jurassic rocks comprise the Junction Creek Sandstone overlain by the Morrison Formation. The Burro Canyon Formation, generally considered to be Lower Cretaceous, may be Late Jurassic in the McElmo Canyon area and is discussed with the Jurassic. The Upper Triassic Chinle Formation in the subsurface underlies, and the Upper Cretaceous Dakota Sandstone overlies, the Jurassic section. An unconformity is present at the base of the Glen Canyon Group (J-0), at the base of the San Rafael Group (J-2), and at the base of the Junction Creek Sandstone (J-5). Another unconformity of Cretaceous age is at the base of the Dakota Sandstone. Most of the Jurassic rocks consist of fluviatile, lacustrine and eolian deposits. The basal part of the Entrada Sandstone and the Wanakah Formation may be of marginal marine origin.

Event-driven sediment flux in Hueneme and Mugu submarine canyons, southern California

USGS Publications Warehouse

Xu, J. P.; Swarzenski, P.W.; Noble, M.; Li, A.-C.

2010-01-01

Vertical sediment fluxes and their dominant controlling processes in Hueneme and Mugu submarine canyons off south-central California were assessed using data from sediment traps and current meters on two moorings that were deployed for 6 months during the winter of 2007. The maxima of total particulate flux, which reached as high as 300+ g/m2/day in Hueneme Canyon, were recorded during winter storm events when high waves and river floods often coincided. During these winter storms, wave-induced resuspension of shelf sediment was a major source for the elevated sediment fluxes. Canyon rim morphology, rather than physical proximity to an adjacent river mouth, appeared to control the magnitude of sediment fluxes in these two submarine canyon systems. Episodic turbidity currents and internal bores enhanced sediment fluxes, particularly in the lower sediment traps positioned 30 m above the canyon floor. Lower excess 210Pb activities measured in the sediment samples collected during periods of peak total particulate flux further substantiate that reworked shelf-, rather than newly introduced river-borne, sediments supply most of the material entering these canyons during storms.

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF... in excess of flat wake speed on the Escalante River from Cow Canyon to Coyote Creek. (3) After...

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF... in excess of flat wake speed on the Escalante River from Cow Canyon to Coyote Creek. (3) After...

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF... in excess of flat wake speed on the Escalante River from Cow Canyon to Coyote Creek. (3) After...

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF... in excess of flat wake speed on the Escalante River from Cow Canyon to Coyote Creek. (3) After...

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF... in excess of flat wake speed on the Escalante River from Cow Canyon to Coyote Creek. (3) After...

Megabenthic assemblages at the Hudson Canyon head (NW Atlantic margin): Habitat-faunal relationships

NASA Astrophysics Data System (ADS)

Pierdomenico, Martina; Gori, Andrea; Guida, Vincent G.; Gili, Josep-Maria

2017-09-01

The distribution of megabenthic communities at the head of Hudson Canyon and adjacent continental shelf was studied by means of underwater video transects and still photo imagery collected using a towed camera system. The goal was to explore the relationships between faunal distribution and physical seafloor conditions and to test the hypothesis that increased seafloor heterogeneity in the Hudson Canyon supports a larger diversity of benthic communities, compared with the adjacent continental shelf. Hierarchical cluster analysis was performed to identify benthic assemblages as defined in imagery. The BIO-ENV procedure and the Canonical Correspondence Analysis were carried out to elucidate species groupings in relation to terrain variables extracted from bathymetric data. Species accumulation curves were generated to evaluate species turn over in and out of Hudson Canyon. The results indicate that seafloor morphology is the main physical factor related to benthic community composition and distribution. Assemblages dominated by sponges, zoanthids and cup corals colonized the canyon margins and flanks, and were associated with coarse-grained sediments, while sea pen assemblages were observed along muddy seafloor within the thalweg. An assemblage dominated by sea stars occurred on the shelf, associated with a sandy seafloor. Some assemblages were exclusively observed in the canyon area, suggesting that the increased variability of seafloor composition, together with the oceanographic processes specific to the canyon area, enhance beta diversity. The colonization by benthic suspension feeders within the canyon, in contrast to shelf assemblages, mainly composed of carnivores and detritus feeders could be favored the intense hydrodynamics at the canyon head that increase the availability of suspended organic matter. From the perspective of management and conservation of marine resources, the results obtained support the relevance of Hudson Canyon as a biodiversity hotspot

Submarine canyons represent an essential habitat network for krill hotspots in a Large Marine Ecosystem.

PubMed

Santora, Jarrod A; Zeno, Ramona; Dorman, Jeffrey G; Sydeman, William J

2018-05-15

Submarine canyon systems are ubiquitous features of marine ecosystems, known to support high levels of biodiversity. Canyons may be important to benthic-pelagic ecosystem coupling, but their role in concentrating plankton and structuring pelagic communities is not well known. We hypothesize that at the scale of a large marine ecosystem, canyons provide a critical habitat network, which maintain energy flow and trophic interactions. We evaluate canyon characteristics relative to the distribution and abundance of krill, critically important prey in the California Current Ecosystem. Using a geological database, we conducted a census of canyon locations, evaluated their dimensions, and quantified functional relationships with krill hotspots (i.e., sites of persistently elevated abundance) derived from hydro-acoustic surveys. We found that 76% of krill hotspots occurred within and adjacent to canyons. Most krill hotspots were associated with large shelf-incising canyons. Krill hotspots and canyon dimensions displayed similar coherence as a function of latitude and indicate a potential regional habitat network. The latitudinal migration of many fish, seabirds and mammals may be enhanced by using this canyon-krill network to maintain foraging opportunities. Biogeographic assessments and predictions of krill and krill-predator distributions under climate change may be improved by accounting for canyons in habitat models.

36 CFR 7.92 - Bighorn Canyon National Recreation Area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Bighorn Canyon National Recreation Area. 7.92 Section 7.92 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.92 Bighorn Canyon National Recreation Area. (a) Aircraft-designated...

Rapid formation of a modern bedrock canyon by a single flood event

NASA Astrophysics Data System (ADS)

Lamb, Michael P.; Fonstad, Mark A.

2010-07-01

Deep river canyons are thought to form slowly over geological time (see, for example, ref. 1), cut by moderate flows that reoccur every few years. In contrast, some of the most spectacular canyons on Earth and Mars were probably carved rapidly during ancient megaflood events. Quantification of the flood discharge, duration and erosion mechanics that operated during such events is hampered because we lack modern analogues. Canyon Lake Gorge, Texas, was carved in 2002 during a single catastrophic flood. The event offers a rare opportunity to analyse canyon formation and test palaeo-hydraulic-reconstruction techniques under known topographic and hydraulic conditions. Here we use digital topographic models and visible/near-infrared aerial images from before and after the flood, discharge measured during the event, field measurements and sediment-transport modelling to show that the flood moved metre-sized boulders, excavated ~7m of limestone and transformed a soil-mantled valley into a bedrock canyon in just ~3days. We find that canyon morphology is strongly dependent on rock type: plucking of limestone blocks produced waterfalls, inner channels and bedrock strath terraces, whereas abrasion of cemented alluvium sculpted walls, plunge pools and streamlined islands. Canyon formation was so rapid that erosion might have been limited by the ability of the flow to transport sediment. We suggest that our results might improve hydraulic reconstructions of similar megafloods on Earth and Mars.

Giant landslides and turbidity currents in the Agadir Canyon Region, NW-Africa

NASA Astrophysics Data System (ADS)

Krastel, Sebastian; Wynn, Russell B.; Stevenson, Christopher; Feldens, Peter; Mehringer, Lisa; Schürer, Anke

2017-04-01

Coring and drilling of the Moroccan Turbidite System off NW-Africa revealed a long sequence of turbidites, mostly sourced from the Moroccan continental margin and the volcanic Canary Islands. The largest individual flow deposits in the Moroccan Turbidite System contain sediment volumes >100 km3, although these large-scale events are relatively infrequent with a recurrence interval of 10,000 years (over the last 200,000 years). The largest siliciclastic flow in the last 200,000 years was the 'Bed 5 event', which transported 160 km3 of sediment up to 2000 km from the Agadir Canyon region to the southwest Madeira Abyssal Plain. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately after initial failure, is a major scientific challenge, which was addressed in the Agadir Canyon source region during RV Maria S. Merian Cruise MSM32 in late 2013. A major landslide area was identified 200 km south of the Agadir Canyon. A landslide was traced from this failure area to the Agadir Canyon. This landslide entered the canyon in about 2500 m water depth. Despite a significant increase in slope angle, the landslide did not disintegrate into a turbidity current when entering the canyon but moved on as landslide for at least another 200 km down the canyon. The age of the landslide ( 145 ka) does not correspond to any major turbidte deposit in the Moroccan Turbidite System, further supporting the fact that the landslide did not disintegrate into a major turbidity current. A core taken about 350 m above the thalweg in the head region of Agadir Canyon shows a single coarse-grained turbidite, which resembles the composition of the Bed 5 event in the Madeira Abyssal Plain. Hence, the Bed 5 turbidite originated as a failure in the

Biodiversity of macrofaunal assemblages from three Portuguese submarine canyons (NE Atlantic)

NASA Astrophysics Data System (ADS)

Cunha, Marina R.; Paterson, Gordon L. J.; Amaro, Teresa; Blackbird, Sabena; de Stigter, Henko C.; Ferreira, Clarisse; Glover, Adrian; Hilário, Ana; Kiriakoulakis, Konstadinos; Neal, Lenka; Ravara, Ascensão; Rodrigues, Clara F.; Tiago, Áurea; Billett, David S. M.

2011-12-01

The macrofaunal assemblages from three Portuguese submarine canyons, Nazaré, Cascais and Setúbal were studied from samples collected at their upper (900-1000 m), middle (3200-3500 m) and lower sections (4200-4500 m) and at the adjacent open slopes (˜1000 m), during the HERMES cruises D297 (R.R.S. Discovery, 2005) CD179 (R.R.S. Charles Darwin, 2006) and 64PE252 (R.V. Pelagia, 2006). The taxonomic composition and patterns in biodiversity, abundance and community structure of the benthic macrofauna were described. Annelida (42.1% of total abundance; 137 species) and Arthropoda (20.6%; 162 species) were, respectively, the most abundant and the most species-rich Phyla among the 342 taxa identified during this study. Multivariate analyses showed significant differences between and within canyons and between canyons and open slope assemblages. At their upper section, canyons supported higher macrofauna abundance but slightly lower biodiversity than the adjacent slopes at similar depth. In all canyons abundance reached the highest value in the middle section and the lowest in the upper section, with marked fluctuations in Nazaré (474-4599 ind. m -2) and lower variability in Cascais (583-1125 ind. m -2). The high abundance and dominance of the assemblages in the middle section of Nazaré and Setúbal was accompanied by depressed biodiversity, while in Cascais, Hurlbert's expected species richness showed increasing values from the upper to the middle canyon, and maintained the high values at the lower section. Overall, the Nazaré Canyon showed the lowest expected species richness (ES (100): 16-39) and the Cascais Canyon the highest (39-54). There was a significant negative Kendall's correlation between total organic carbon concentrations in the superficial sediments and ES (100) and a significant positive correlation between total nitrogen and macrofauna density. The influences of organic enrichment, sediment heterogeneity and hydrodynamic regime on the abundance

Preliminary report on the geology and hydrology of Mortandad Canyon near Los Alamos, New Mexico, with reference to disposal of liquid low-level radioactive waste

USGS Publications Warehouse

Baltz, E.H.; Abrahams, J.H.; Purtyman, W.D.

1963-01-01

The U.S. Geological Survey, in cooperation with the U.S. Atomic Energy Commission and the Los Alamos Scientific Laboratory, selected the upper part of Mortandad Canyon near Los Alamos, New Mexico for a site for disposal of treated liquid low-level radioactive waste. This report summarizes the part of a study of the geology and hydrology that was done from October 1960 through June 1961. Additional work is being continued. Mortandad Canyon is a narrow east-southeast-trending canyon about 9? miles long that heads on the central part of the Pajarito Plateau at an altitude of about 7,340 feet. The canyon is tributary to the Rio Grande. The drainage area of the part of Mortandad Canyon that was investigated is about 2 square miles, and the total drainage area is about 4.9 square miles. The Pajarito Plateau is capped by the Bandelier Tuff of Pleistocene age. Mortandad Canyon is cut in the Bandelier, and alluvium covers the floor of the canyon to depths ranging from less than 1 foot to as much as 100 feet. The Bandelier is underlain by silt, sand, conglomerate, and interbedded basalt of the Santa Fe Group of Miocene, Pliocene, and Pleistocene(?) age. Some ground water is perched in the alluvium in the canyon; however, the top of the main aquifer is in the Santa Fe Group at a depth of about 990 feet below the canyon floor. Joints in the Bandelier Tuff probably were caused by shrinkage of the tuff during cooling. The joints range in width from hairline cracks to fissures several inches wide. Water can infiltrate along the open joints where the Bandelier is at the surface; however, soil, alluvial fill, and autochthonous clay inhibit infiltration on the tops of mesas and probably in the alluvium-floored canyons also. Thirty-three test holes, each less than 100 feet deep, were drilled in 10 lies across Mortandad Canyon from the western margin of the study area to just west of the Los Alamos-Santa Fe County line. Ten of the holes were cased for observation wells to measure

Re-collection of Fish Canyon Tuff for fission-track standardization

USGS Publications Warehouse

Naeser, C.W.; Cebula, G.T.

1984-01-01

The PURPOSE of this note is to announce the availability of apatite and zircon from a third collection of the Oligocene Fish Canyon Tuff (FC-3). Apatite and zircon separated from the Fish Canyon Tuff have prove to be a useful standard for fission-track dating, both for interlaboratory comparisons and for checking procedures within a laboratory. In May 1981, about 540 kg of Fish Canyon Tuff were collected for mineral separation. Approximately 7. 5 g of apatite, 6. 5 g of zircon, and 89 g of sphene were recovered from this collection. This new material is now ready for distribution.

Element concentrations in surface soils of the Coconino Plateau, Grand Canyon region, Coconino County, Arizona

USGS Publications Warehouse

Van Gosen, Bradley S.

2016-09-15

This report provides the geochemical analyses of a large set of background soils collected from the surface of the Coconino Plateau in northern Arizona. More than 700 soil samples were collected at 46 widespread areas, sampled from sites that appear unaffected by mineralization and (or) anthropogenic contamination. The soils were analyzed for 47 elements, thereby providing data on metal concentrations in soils representative of the plateau. These background concentrations can be used, for instance, for comparison to metal concentrations found in soils potentially affected by natural and anthropogenic influences on the Coconino Plateau in the Grand Canyon region of Arizona.The soil sampling survey revealed low concentrations for the metals most commonly of environmental concern, such as arsenic, cobalt, chromium, copper, mercury, manganese, molybdenum, lead, uranium, vanadium, and zinc. For example, the median concentrations of the metals in soils of the Coconino Plateau were found to be comparable to the mean values previously reported for soils of the western United States.

H-Canyon Recovery Crawler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kriikku, E. M.; Hera, K. R.; Marzolf, A. D.

The Nuclear Material Disposition Project group asked the Savannah River National Lab (SRNL) Research and Development Engineering (R&DE) department to help procure, test, and deploy a remote crawler to recover the 2014 Inspection Crawler (IC) that tipped over in the H-Canyon Air Exhaust Tunnel. R&DE wrote a Procurement Specification for a Recovery Crawler (RC) and SRNS Procurement Department awarded the contract to Power Equipment Manufacturing Inc. (PEM). The PEM RC was based on their standard sewer inspection crawler with custom arms and forks added to the front. The arms and forks would be used to upright the 2014 Inspection Crawler.more » PEM delivered the RC and associated cable reel, 2014 Inspection Crawler mockup, and manuals in late April 2015. R&DE and the team tested the crawler in May of 2015 and made modifications based on test results and Savannah River Site (SRS) requirements. R&DE delivered the RC to H-Area at the end of May. The team deployed the RC on June 9, 10, and 11, 2015 in the H-Canyon Air Exhaust Tunnel. The RC struggled with some obstacles in the tunnel, but eventually made it to the IC. The team spent approximately five hours working to upright the IC and eventually got it on its wheels. The IC travelled approximately 20 feet and struggled to drive over debris on the air tunnel floor. Unfortunately the IC tripped over trying to pass this obstacle. The team decided to leave the IC in this location and inspect the tunnel with the RC. The RC passed the IC and inspected the tunnel as it travelled toward H-Canyon. The team turned the RC around when it was about 20 feet from the H-Canyon crossover tunnel. From that point, the team drove the RC past the manway towards the new sand filter and stopped approximately 20 feet from the new sand filter. The team removed the RC from the tunnel, decontaminated the RC, and stored it the manway building, 294-2H. The RC deployment confirmed the IC was not in a condition to perform useful tunnel inspections

33 CFR 165.1171 - Copper Canyon, Lake Havasu, Colorado River-Regulated Navigation Area.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Copper Canyon, Lake Havasu... Guard District § 165.1171 Copper Canyon, Lake Havasu, Colorado River—Regulated Navigation Area. (a) Location. The following is a regulated navigation area: (1) In the water area of Copper Canyon, Lake Havasu...

33 CFR 165.1171 - Copper Canyon, Lake Havasu, Colorado River-Regulated Navigation Area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Copper Canyon, Lake Havasu... Guard District § 165.1171 Copper Canyon, Lake Havasu, Colorado River—Regulated Navigation Area. (a) Location. The following is a regulated navigation area: (1) In the water area of Copper Canyon, Lake Havasu...

A Numerical Simulation of Traffic-Related Air Pollution Exposures in Urban Street Canyons

NASA Astrophysics Data System (ADS)

Liu, J.; Fu, X.; Tao, S.

2016-12-01

Urban street canyons are usually associated with intensive vehicle emissions. However, the high buildings successively along both sides of a street block the dispersion of traffic-generated air pollutants, which enhances human exposure and adversely affects human health. In this study, an urban scale traffic pollution dispersion model is developed with the consideration of street distribution, canyon geometry, background meteorology, traffic assignment, traffic emissions and air pollutant dispersion. Vehicle exhausts generated from traffic flows will first disperse inside a street canyon along the micro-scale wind field (generated by computational fluid dynamics (CFD) model) and then leave the street canyon and further disperse over the urban area. On the basis of this model, the effects of canyon geometry on the distribution of NOx and CO from traffic emissions were studied over the center of Beijing, China. We found that an increase of building height along the streets leads to higher pollution levels inside streets and lower pollution levels outside, resulting in higher domain-averaged concentrations over the area. In addition, street canyons with equal (or highly uneven) building heights on two sides of a street tend to lower the urban-scale air pollution concentrations at pedestrian level. Our results indicate that canyon geometry strongly influences human exposure to traffic pollutants in the populated urban area. Carefully planning street layout and canyon geometry in consideration of traffic demand as well as local weather pattern may significantly reduce the chances of unhealthy air being inhaled by urban residents.

Variability of CO2 concentrations and fluxes in and above an urban street canyon

NASA Astrophysics Data System (ADS)

Lietzke, Björn; Vogt, Roland

2013-08-01

The variability of CO2 concentrations and fluxes in dense urban environments is high due to the inherent heterogeneity of these complex areas and their spatio-temporally variable anthropogenic sources. With a focus on micro- to local-scale CO2-exchange processes, measurements were conducted in a street canyon in the city of Basel, Switzerland in 2010. CO2 fluxes were sampled at the top of the canyon (19 m) and at 39 m while vertical CO2 concentration profiles were measured in the center and at a wall of the canyon. CO2 concentration distributions in the street canyon and exchange processes with the layers above show, apart from expected general diurnal patterns due mixing layer heights, a strong dependence on wind direction relative to the canyon. As a consequence of the resulting corkscrew-like canyon vortex, accumulation of CO2 inside the canyon is modulated with distinct distribution patterns. The evaluation of diurnal traffic data provides good explanations for the vertical and horizontal differences in CO2-distribution inside the canyon. Diurnal flux characteristics at the top of the canyon can almost solely be explained with traffic density expressed by the strong linear dependence. Even the diurnal course of the flux at 39 m shows a remarkable relationship to traffic density for east wind conditions while, for west wind situations, a change toward source areas with lower emissions leads to a reduced flux.

Mineral resources of the Sheepshead Mountains, Wildcat Canyon, and Table Mountain Wilderness Study Areas, Malheur and Harney counties, Oregon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sherrod, D.R.; Griscom, A.; Turner, R.L.

1988-01-01

The Sheepshead Mountains, Wildcat Canyon, and Table Mountain Wilderness Study Areas encompass most of the Sheepshead Mountains in southeast Oregon. The mountains comprise several fault blocks of middle and late Miocene basalt, basaltic andesite, andesite, and dacite lava; pyroclastic and sedimentary rocks are minor. The three wilderness study areas have low resource potential for gold, silver, and oil and gas. A few small areas have low-to-high resource potential for diatomite, as indicated by the occurrence of low-grade diatomite. Some fault zones have a moderate potential for geothermal energy.

Macrofaunal Patterns in and around du Couedic and Bonney Submarine Canyons, South Australia

PubMed Central

Dittmann, Sabine; Sorokin, Shirley J.; Hendrycks, Ed

2015-01-01

Two South Australian canyons, one shelf-incising (du Couedic) and one slope-limited (Bonney) were compared for macrofaunal patterns on the shelf and slope that spanned three water masses. It was hypothesized that community structure would (H1) significantly differ by water mass, (H2) show significant regional differences and (H3) differ significantly between interior and exterior of each canyon. Five hundred and thirty-one species of macrofauna ≥1 mm were captured at 27 stations situated in depth stratified transects inside and outside the canyons from 100 to1500 m depth. The macrofauna showed a positive relationship to depth in abundance, biomass, species richness and community composition while taxonomic distinctness and evenness remained high at all depths. Biotic variation on the shelf was best defined by variation in bottom water primary production while sediment characteristics and bottom water oxygen, temperature and nutrients defined biotic variation at greater depth. Community structure differed significantly (p<0.01) among the three water masses (shelf-flowing South Australian current, upper slope Flinders current and lower slope Antarctic Intermediate Water) (H1). Although community differences between the du Couedic and Bonney regions were marginally above significance at p = 0.05 (H2), over half of the species captured were unique to each region. This supports the evidence from fish and megafaunal distributions that the du Couedic and Bonney areas are in different bioregions. Overall, the canyon interiors were not significantly different in community composition from the exterior (H3). However, both canyons had higher abundance and/or biomass, increased species dominance, different species composition and coarser sediments near the canyon heads compared to outside the canyons at the same depth (500 m), suggestive of heightened currents within the canyons that influence community composition there. At 1000–1500 m, the canyon interiors were

Geologic framework of thermal springs, Black Canyon, Nevada and Arizona

USGS Publications Warehouse

Beard, L. Sue; Anderson, Zachary W.; Felger, Tracey J.; Seixas, Gustav B.

2014-01-01

Thermal springs in Black Canyon of the Colorado River, downstream of Hoover Dam, are important recreational, ecological, and scenic features of the Lake Mead National Recreation Area. This report presents the results from a U.S. Geological Survey study of the geologic framework of the springs. The study was conducted in cooperation with the National Park Service and funded by both the National Park Service and National Cooperative Geologic Mapping Program of the U.S. Geological Survey. The report has two parts: A, a 1:48,000-scale geologic map created from existing geologic maps and augmented by new geologic mapping and geochronology; and B, an interpretive report that presents results based on a collection of fault kinematic data near springs within Black Canyon and construction of 1:100,000-scale geologic cross sections that extend across the western Lake Mead region. Exposures in Black Canyon are mostly of Miocene volcanic rocks, underlain by crystalline basement composed of Miocene plutonic rocks or Proterozoic metamorphic rocks. The rocks are variably tilted and highly faulted. Faults strike northwest to northeast and include normal and strike-slip faults. Spring discharge occurs along faults intruded by dacite dikes and plugs; weeping walls and seeps extend away from the faults in highly fractured rock or relatively porous volcanic breccias, or both. Results of kinematic analysis of fault data collected along tributaries to the Colorado River indicate two episodes of deformation, consistent with earlier studies. The earlier episode formed during east-northeast-directed extension, and the later during east-southeast-directed extension. At the northern end of the study area, pre-existing fault blocks that formed during the first episode were rotated counterclockwise along the left-lateral Lake Mead Fault System. The resulting fault pattern forms a complex arrangement that provides both barriers and pathways for groundwater movement within and around Black

Standardized methods for Grand Canyon fisheries research 2015

USGS Publications Warehouse

Persons, William R.; Ward, David L.; Avery, Luke A.

2013-01-01

This document presents protocols and guidelines to persons sampling fishes in the Grand Canyon, to help ensure consistency in fish handling, fish tagging, and data collection among different projects and organizations. Most such research and monitoring projects are conducted under the general umbrella of the Glen Canyon Dam Adaptive Management Program and include studies by the U.S. Geological Survey (USGS), U.S. Fish and Wildlife Service (FWS), National Park Service (NPS), the Arizona Game and Fish Department (AGFD), various universities, and private contractors. This document is intended to provide guidance to fieldworkers regarding protocols that may vary from year to year depending on specific projects and objectives. We also provide herein documentation of standard methods used in the Grand Canyon that can be cited in scientific publications, as well as a summary of changes in protocols since the document was first created in 2002.

75 FR 34476 - Glen Canyon Dam Adaptive Management Work Group

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-17

... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Management Work Group. The purpose of the Adaptive Management Work Group is to advise and to provide... of the Glen Canyon Dam Adaptive Management Work Group is in the public interest in connection with...

Influence of a dam on fine-sediment storage in a canyon river

USGS Publications Warehouse

Hazel, J.E.; Topping, D.J.; Schmidt, J.C.; Kaplinski, M.

2006-01-01

Glen Canyon Dam has caused a fundamental change in the distribution of fine sediment storage in the 99-km reach of the Colorado River in Marble Canyon, Grand Canyon National Park, Arizona. The two major storage sites for fine sediment (i.e., sand and finer material) in this canyon river are lateral recirculation eddies and the main-channel bed. We use a combination of methods, including direct measurement of sediment storage change, measurements of sediment flux, and comparison of the grain size of sediment found in different storage sites relative to the supply and that in transport, in order to evaluate the change in both the volume and location of sediment storage. The analysis shows that the bed of the main channel was an important storage environment for fine sediment in the predam era. In years of large seasonal accumulation, approximately 50% of the fine sediment supplied to the reach from upstream sources was stored on the main-channel bed. In contrast, sediment budgets constructed for two short-duration, high experimental releases from Glen Canyon Dam indicate that approximately 90% of the sediment discharge from the reach during each release was derived from eddy storage, rather than from sandy deposits on the main-channel bed. These results indicate that the majority of the fine sediment in Marble Canyon is now stored in eddies, even though they occupy a small percentage (???17%) of the total river area. Because of a 95% reduction in the supply of fine sediment to Marble Canyon, future high releases without significant input of tributary sediment will potentially erode sediment from long-term eddy storage, resulting in continued degradation in Marble Canyon. Copyright 2006 by the American Geophysical Union.

Water-quality data for Walnut Canyon and Wupatki National Monuments, Arizona, 2001-02

USGS Publications Warehouse

Thomas, Blakemore E.

2003-01-01

Water-quality data are provided for four sites in Walnut Canyon and Wupatki National Monuments in north-central Arizona. These data describe the current water quality and provide baseline water-quality information for monitoring future trends. Water samples were collected from a ground-water seep and well in Walnut Canyon and from a spring and a river in Wupatki during September 2001 to September 2002. Water from the four sites is from four different sources. In Walnut Canyon, Cherry Canyon seep is in a shallow local aquifer, and the Little Colorado River contains ground-water discharge from several aquifers and runoff from a 22,000 square-mile drainage area. Concentrations of dissolved solids were similar within the two monuments; the range for water samples from Walnut Canyon was 203 to 248 milligrams per liter, and the range for water samples from Wupatki was 503 to 614 milligrams per liter. Concentrations of trace elements were generally low in water samples from the three ground-water sites--Cherry Canyon seep, Walnut Canyon headquarters well, and Heiser Spring. The water sample collected from the Little Colorado River, however, had high concentrations of aluminum (4,020 micrograms per liter), antimony (54 micrograms per liter), arsenic (14.3 micrograms per liter), and iron (749 micrograms per liter) relative to U.S. Environmental Protection Agency Primary and Secondary Maximum Contaminant Levels. Concentrations of nitrate (as nitrogen) in water samples from the four sites were generally low (0.11 to 1.8 milligrams per liter) and are within the upper 25 percent of nitrate concentrations measured in the regional aquifer near Flagstaff in 1996 and 1997. Water samples from Cherry Canyon seep, Heiser Spring, and the Little Colorado River contained total coliform bacteria. Fecal coliform and Escherichia coli bacteria were found in water samples from Cherry Canyon seep and the Little Colorado River.

Martian canyons and African rifts: Structural comparisons and implications

NASA Technical Reports Server (NTRS)

Frey, H. V.

1978-01-01

The resistant parts of the canyon walls of the Martian rift complex Valled Marineris were used to infer an earlier, less eroded reconstruction of the major roughs. The individual canyons were then compared with individual rifts of East Africa. When measured in units of planetary radius, Martian canyons show a distribution of lengths nearly identical to those in Africa, both for individual rifts and for compound rift systems. A common mechanism which scales with planetary radius is suggested. Martian canyons are significantly wider than African rifts. The overall pattern of the rift systems of Africa and Mars are quite different in that the African systems are composed of numerous small faults with highly variable trend. On Mars the trends are less variable; individual scarps are straighter for longer than on earth. This is probably due to the difference in tectonic histories of the two planets: the complex history of the earth and the resulting complicated basement structures influence the development of new rifts. The basement and lithosphere of Mars are inferred to be simple, reflecting a relatively inactive tectonic history prior to the formation of the canyonlands.

Are amphitheater headed canyons indicative of a particular formative process?

NASA Astrophysics Data System (ADS)

Ryan, A. J.; Whipple, K. X.; Johnson, J. P.

2012-12-01

Tributary canyons with amphitheater-shaped heads have previously been interpreted as evidence for groundwater seepage erosion, particularly in environments where fluvial processes are assumed to be negligible. However, some have questioned whether this canyon morphology is truly diagnostic of a particular formative process. We seek to determine the relative roles of fluvial and groundwater-related processes and the strength of stratigraphic control on the Colorado Plateau through a combination of fieldwork and GIS analysis. Amphitheater valleys may have overhanging or steep-sided headwalls with a semicircular plan-view pattern. It is reasonable to assume that this form is a result of focused erosion at the base of the headwall (i.e. sapping). Two frequently cited agents may lead to undermining: plunge-pool scour at the base of waterfalls and seepage induced weathering and erosion where the groundwater table intersects the land surface. Both processes are enhanced where weaker, less permeable layers underlie stronger cap rock. We conducted preliminary fieldwork in two locations on the Colorado Plateau, where there are many classic examples of amphitheater headed canyons. The Escalante River landscape is highly variable with a range of canyon and valley-head forms, many of which cut through the thick Navajo Sandstone into the underlying shale and sand of the Kayenta Formation. Northeast of Escalante National Monument, at the base of the Henry Mountains, is Tarantula Mesa. The canyons there are also considerably variable, with nearly all containing at least one abrupt amphitheater knickpoint at the valley head or farther downstream. Our observations are presented here with an analysis of the canyon profiles, surrounding topography, and potential structural controls. We have found that nearly all amphitheaters in both locales show signs of groundwater seepage weathering and plausibly seepage erosion. However, many also contain plunge pools and evidence of substantial

Effects of building roof greening on air quality in street canyons

NASA Astrophysics Data System (ADS)

Baik, Jong-Jin; Kwak, Kyung-Hwan; Park, Seung-Bu; Ryu, Young-Hee

2012-12-01

Building roof greening is a successful strategy for improving urban thermal environment. It is of theoretical interest and practical importance to study the effects of building roof greening on urban air quality in a systematic and quantitative way. In this study, we examine the effects of building roof greening on air quality in street canyons using a computational fluid dynamics (CFD) model that includes the thermodynamic energy equation and the transport equation of passive, non-reactive pollutants. For simplicity, building roof greening is represented by specified cooling. Results for a simple building configuration with a street canyon aspect ratio of one show that the cool air produced due to building roof greening flows into the street canyon, giving rise to strengthened street canyon flow. The strengthened street canyon flow enhances pollutant dispersion near the road, which decreases pollutant concentration there. Thus, building roof greening improves air quality near the road. The degree of air quality improvement near the road increases as the cooling intensity increases. In the middle region of the street canyon, the air quality can worsen when the cooling intensity is not too strong. Results for a real urban morphology also show that building roof greening improves air quality near roads. The degree of air quality improvement near roads due to building roof greening depends on the ambient wind direction. These findings provide a theoretical foundation for constructing green roofs for the purpose of improving air quality near roads or at a pedestrian level as well as urban thermal environment. Further studies using a CFD model coupled with a photochemistry model and a surface energy balance model are required to evaluate the effects of building roof greening on air quality in street canyons in a more realistic framework.

Bedrock Canyons Carved by the Largest Known Floods on Earth and Mars

NASA Astrophysics Data System (ADS)

Lamb, M. P.; Lapôtre, M. G. A.; Larsen, I. J.; Williams, R. M. E.

2017-12-01

The surface of Earth is a dynamic and permeable interface where the rocky crust is sculpted by ice, wind and water resulting in spectacular mountain ranges, vast depositional basins and environments that support life. These landforms and deposits contain a rich, yet incomplete, record of Earth history that we are just beginning to understand. Some of the most dramatic landforms are the huge bedrock canyons carved by catastrophic floods. On Mars, similar bedrock canyons, known as Outflow Channels, are the most important indicators of large volumes of surface water in the past. Despite their importance and now decades of observations of canyon morphology, we lack a basic understanding of how the canyons formed, which limits our ability to reconstruct flood discharge, duration and water volume. In this presentation I will summarize recent work - using mechanistic numerical models and field observations - that suggests that bedrock canyons carved by megafloods rapidly evolve to a size and shape such that boundary shear stresses just exceed that required to entrain fractured blocks of rock. The threshold shear stress constraint allows for quantitative reconstruction of the largest known floods on Earth and Mars, and implies far smaller discharges than previous methods that assume flood waters fully filled the canyons to high water marks.

Wall-rock control of cortain pitchblende deposits in Golden Gate Canyon, Jefferson County, Colorado

USGS Publications Warehouse

Adams, John W.; Stugard, Frederick

1954-01-01

Carbonate veins cutting pre-Cambrian metamorphic rocks in Golden Gate Canyon contain pitchblende and base-metal sulfides. The veins occupy extensive faults of Laramide age but normally contain pitchblende only where the cut hornblende gneiss. At the Union Pacific prospect, which was studied in detail, pitchblende, hermatite, and some ankerite formed in advance of sulfides, except possibly for minor pyrite. Base-metal sulfides and the bulk of ankerite-calcite vein-filling were deposited after the pitchblende. Chemical analyses show a high ferrous iron content in the hornblende gneiss in contrast to low ferrous iron in the adjacent biotite gneiss. It is hypothesized that ferrous iron released by alteration of hornblende was partly oxidized to hematite by the ore-bearing solutions and, contemporaneously, uranium was reduced and deposited as pitchblende. In other veins, biotite or iron sulfides may have been similarly effective in precipitating pitchblende. Apparently both the ferrous ion and the sulfide ion can serve as reducing agents and control pitchblende deposition. It is suggested that conditions particularly favorable for uranium deposition are present where uranium-bearing solutions had access to rocks rich in ferrous iron or pre-existing sulfides.

3D View of Grand Canyon, Arizona

NASA Technical Reports Server (NTRS)

2000-01-01

The Grand Canyon is one of North America's most spectacular geologic features. Carved primarily by the Colorado River over the past six million years, the canyon sports vertical drops of 5,000 feet and spans a 445-kilometer-long stretch of Arizona desert. The strata along the steep walls of the canyon form a record of geologic time from the Paleozoic Era (250 million years ago) to the Precambrian (1.7 billion years ago).

The above view was acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument aboard the Terra spacecraft. Visible and near infrared data were combined to form an image that simulates the natural colors of water and vegetation. Rock colors, however, are not accurate. The image data were combined with elevation data to produce this perspective view, with no vertical exaggeration, looking from above the South Rim up Bright Angel Canyon towards the North Rim. The light lines on the plateau at lower right are the roads around the Canyon View Information Plaza. The Bright Angel Trail, which reaches the Colorado in 11.3 kilometers, can be seen dropping into the canyon over Plateau Point at bottom center. The blue and black areas on the North Rim indicate a forest fire that was smoldering as the data were acquired on May 12, 2000.

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land

Pollutant Concentrations in Street Canyons of Different Aspect Ratio with Avenues of Trees for Various Wind Directions

NASA Astrophysics Data System (ADS)

Gromke, Christof; Ruck, Bodo

2012-07-01

This study summarizes the effects of avenues of trees in urban street canyons on traffic pollutant dispersion. We describe various wind-tunnel experiments with different tree-avenue models in combination with variations in street-canyon aspect ratio W/ H (with W the street-canyon width and H the building height) and approaching wind direction. Compared to tree-free street canyons, in general, higher pollutant concentrations are found. Avenues of trees do not suppress canyon vortices, although the air ventilation in canyons is hindered significantly. For a perpendicular wind direction, increases in wall-average and wall-maximum concentrations at the leeward canyon wall and decreases in wall-average concentrations at the windward wall are found. For oblique and perpendicular wind directions, increases at both canyon walls are obtained. The strongest effects of avenues of trees on traffic pollutant dispersion are observed for oblique wind directions for which also the largest concentrations at the canyon walls are found. Thus, the prevailing assumption that attributes the most harmful dispersion conditions to a perpendicular wind direction does not hold for street canyons with avenues of trees. Furthermore, following dimensional analysis, an estimate of the normalized wall-maximum traffic pollutant concentration in street canyons with avenues of trees is derived.

Structure, Quaternary history, and general geology of the Corral Canyon area, Los Angeles County, California

USGS Publications Warehouse

Yerkes, R.F.; Wentworth, Carl M.

1965-01-01

The Corral Canyon nuclear power plant site consists of about 305 acres near the mouth of Corral Canyon in the central Santa Monica Mountains; it is located on an east-trending segment of the Pacific Coast between Point Dume and Malibu Canyon, about 28 miles due west of Los Angeles. The Santa Monica Mountains are the southwesternmost mainland part of the Transverse Ranges province, the east-trending features of which transect the otherwise relatively uniform northwesterly trend of the geomorphic and geologic features of coastal California. The south margin of the Transverse Ranges is marked by the Santa Monica fault system, which extends eastward near the 34th parallel for at least 145 miles from near Santa Cruz Island to the San Andreas fault zone. In the central Santa Monica Mountains area the Santa Monica fault system includes the Malibu Coast fault and Malibu Coast zone of deformation on the north; from the south it includes an inferred fault--the Anacapa fault--considered to follow an east-trending topographic escarpmemt on the sea floor about 5 miles south of the Malibu Coast fault. The low-lying terrain south of the fault system, including the Los Angeles basin and the largely submerged Continental Borderland offshore, are dominated by northwest-trending structural features. The Malibu Coat zone is a wide, east-trending band of asymmetrically folded, sheared, and faulted bedrock that extends for more than 20 miles along the north margin of the Santa Monica fault system west of Santa Monica. Near the north margin of the Malibu Coast zone the north-dipping, east-trending Malibu Coast fault juxtaposes unlike, in part contemporaneous sedimentary rock sections; it is inferred to be the near-surface expression of a major crustal boundary between completely unrelated basement rocks. Comparison of contemporaneous structural features and stratigraphic sections (Late Cretaceous to middle Miocene sedimentary, rocks and middle Miocene volcanic and intrusive igneous rocks

Effect of stable stratification on dispersion within urban street canyons: A large-eddy simulation

NASA Astrophysics Data System (ADS)

Li, Xian-Xiang; Britter, Rex; Norford, Leslie K.

2016-11-01

This study employs a validated large-eddy simulation (LES) code with high tempo-spatial resolution to investigate the effect of a stably stratified roughness sublayer (RSL) on scalar transport within an urban street canyon. The major effect of stable stratification on the flow and turbulence inside the street canyon is that the flow slows down in both streamwise and vertical directions, a stagnant area near the street level emerges, and the vertical transport of momentum is weakened. Consequently, the transfer of heat between the street canyon and overlying atmosphere also gets weaker. The pollutant emitted from the street level 'pools' within the lower street canyon, and more pollutant accumulates within the street canyon with increasing stability. Under stable stratification, the dominant mechanism for pollutant transport within the street canyon has changed from ejections (flow carries high-concentration pollutant upward) to unorganized motions (flow carries high-concentration pollutant downward), which is responsible for the much lower dispersion efficiency under stable stratifications.

Fourmile Canyon Fire Findings

Treesearch

Russell Graham; Mark Finney; Chuck McHugh; Jack Cohen; Dave Calkin; Rick Stratton; Larry Bradshaw; Ned Nikolov

2012-01-01

The Fourmile Canyon Fire burned in the fall of 2010 in the Rocky Mountain Front Range adjacent to Boulder, Colorado. The fire occurred in steep, rugged terrain, primarily on privately owned mixed ponderosa pine and Douglas-fir forests. The fire started on September 6 when the humidity of the air was very dry (¡Ö

Describing the development of submarine canyons using stream-power erosion laws

NASA Astrophysics Data System (ADS)

Mitchell, N. C.

2004-12-01

The problem of how turbidity currents erode their beds is important for understanding how canyons develop, but is complex because flow power also varies as a result of incorporation and deposition of the current's suspended load. In some canyons where the total sedimentary mass passing through the canyon has been much larger than the excavated mass, the loads of the eroding currents changed little during passage down-canyon. Canyon morphology can then potentially reveal how gradient and other factors affect erosion rate, illustrated here with two datasets from tectonically active margins. The first dataset is from Tenryu Canyon off Japan, which was entrenched by up to 1200 m by steepening of the Tokai accretionary prism. Incision depth and channel gradient S data [Soh and Tokuyama, 2002] suggest an erosion law in which incision rate E~S0.8, which is remarkably similar to laws for detachment-limited erosion of river beds. In the second dataset, folds of the Barbados prism have created knickpoints [Huyghe et al., 2004]. Numerical modeling reveals that the knickpoints have partly smoothed out, a property of transport-limited erosion, but primarily have translated, a property of detachment-limited erosion. This mixed style of knickpoint development has also been inferred from some bedrock eroding streams on land. If scaling arguments for erosion with flow velocity apply here [Hancock et al., 1998], the inferred dependence of erosion rate on gradient implies that plucking and shear failure rather than abrasion are the main mechanisms in these channels. Hancock, G.S., Anderson, R.S., and Whipple, K.X., 1998, Beyond power: bedrock river incision process and form, in Tinkler, K.J., and Wohl, E.E., eds., Rivers over rock: Fluvial processes in bedrock channels, American Geophysical Union Monogr. 107: p. 35-60. Huyghe, P., M. Foata, E. Deville, and the Caramba Working Group, Channel profiles through the active thrust front of the southern Barbados prism, Geology, 32, 429

78 FR 21415 - Glen Canyon Dam Adaptive Management Work Group

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-10

...: The Glen Canyon Dam Adaptive Management Program (AMP) was implemented as a result of the Record of... consultation requirements of the Grand Canyon Protection Act (Pub. L. 102-575) of 1992. The AMP includes a.../amp/amwg/mtgs/13may08/index.html . Time will be allowed for any individual or organization wishing to...

Evidence of Trawl-Induced Resuspension at the Whittard Canyon, NE Atlantic?

NASA Astrophysics Data System (ADS)

Wilson, A. M.; Kiriakoulakis, K.; Raine, R.; Gerritsen, H. D.; Blackbird, S.; Allcock, A. L.; White, M. G.

2016-02-01

Four research surveys (2011-2014) to the Whittard Canyon have taken place as part of an Irish Bio-discovery and Ecosystem functioning project. Hydrographic observations including turbidity measurements and samples for biogeochemical analysis were collected in order to improve our understanding of sediment transport, biogeochemical cycling and trophic food webs within canyons. Benthic and intermediate nepheloid layers were detected during all four surveys, in eastern and western branches of the canyon. These layers act as a pathway from productive shelf environments to the deep abyss. Unusual peaks in turbidity were detected in two branches of the canyon in June 2013. These turbidity peaks, termed Enhanced Nepheloid Layers (ENLs), had elevated suspended particulate matter concentrations exceeding 1 mg L-1. Typically, concentrations of material in nepheloid layers range between 0.28-0.6 mg L-1, while the largest ENLs measured between 2-8 mg L-1. The ENLs measured 100-260 m in vertical height and were detected in water depths of between 640-2880 m. Vessel Monitoring System data showed that high spatial and temporal activity of potential bottom trawling vessels coincided with the occurrence of the ENLs. Molar C/N ratios of the suspended organic material from the ENLs showed a high degree of degradation. While trawling has previously been suspected to affect the Whittard Canyon, this is the first study to provide evidence of such activity. Regular occurrences of these events are likely to have implications for increased sediment fluxes, burial of organic carbon and alteration of benthic and canyon ecosystems.

Impact of roof height non-uniformity on pollutant transport between a street canyon and intersections.

PubMed

Nosek, Štěpán; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Jaňour, Zbyněk

2017-08-01

This paper presents an extension of our previous wind-tunnel study (Nosek et al., 2016) in which we highlighted the need for investigation of the removal mechanisms of traffic pollution from all openings of a 3D street canyon. The extension represents the pollution flux (turbulent and advective) measurements at the lateral openings of three different 3D street canyons for the winds perpendicular and oblique to the along-canyon axis. The pollution was simulated by emitting a passive gas (ethane) from a homogeneous ground-level line source positioned along the centreline of the investigated street canyons. The street canyons were formed by courtyard-type buildings of two different regular urban-array models. The first model has a uniform building roof height, while the second model has a non-uniform roof height along each building's wall. The mean flow and concentration fields at the canyons' lateral openings confirm the findings of other studies that the buildings' roof-height variability at the intersections plays an important role in the dispersion of the traffic pollutants within the canyons. For the perpendicular wind, the non-uniform roof-height canyon appreciably removes or entrains the pollutant through its lateral openings, contrary to the uniform canyon, where the pollutant was removed primarily through the top. The analysis of the turbulent mass transport revealed that the coherent flow structures of the lateral momentum transport correlate with the ventilation processes at the lateral openings of all studied canyons. These flow structures coincide at the same areas and hence simultaneously transport the pollutant in opposite directions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Erosional threshold for the formation of bedrock canyons carved by megafloods on Earth and Mars

NASA Astrophysics Data System (ADS)

Lamb, Michael P.; Lapotre, Mathieu G. A.; Larsen, Isaac J.; Williams, Rebecca M. E.

2017-04-01

Enormous canyons have been carved into the surfaces of Earth and Mars by catastrophic outbursts of water. On Mars, these bedrock canyons, known as the planetary-scale outflow channels, are the most important indicator of large volumes of flowing water in the planet's history. Despite their importance and now decades of observations of canyon morphology, we lack a basic understanding of how the canyons formed, which limits our ability to reconstruct flood discharge, duration, and water volume. In this presentation I will summarize recent work - using mechanistic numerical models and field observations of similar landforms on Earth - that suggests that bedrock canyons carved by megafloods may rapidly evolve to a size and shape in which boundary shear stress just exceeds that required to entrain fractured blocks of rock. Recent advances in theory for plucking, sliding and toppling of fractured rock allow for quantitative constraints on erosion thresholds. Coupling these erosional constraints with 2-D hydrodynamic models at waterfalls shows that cataracts in basalt, which are common in megaflood terrain, evolve to a threshold state such that canyon width accurately reflects flood discharge. The erosional threshold hypothesis also is consistent with the formation of gravel bars in the Channeled Scablands of the Missoula Floods, USA, and with observations of a small flood-carved canyon from a dam overflow event in 2002 in Texas. Together, these studies suggest that canyons progressively erode in concert with megaflooding, such that flood waters never fully filled the final canyon relief, implying smaller flood discharges and longer durations than models that assume near canyon-filling floods routed over modern topography.

Mapping wilderness character in Sequoia and Kings Canyon National Parks

Treesearch

James Tricker; Peter Landres; Gregg Fauth; Paul Hardwick; Alex Eddy

2014-01-01

The Sequoia-Kings Canyon Wilderness was established in September of 1984 when President Ronald Reagan signed the California Wilderness Act (PL 98-425). In March 2009, President Barack Obama signed the Omnibus Public Land Management Act (PL 111-11) designating the John Krebs Wilderness and the Sequoia-Kings Canyon Wilderness Addition (all wholly contained within SEKI)....

Internal tides affect benthic community structure in an energetic submarine canyon off SW Taiwan

NASA Astrophysics Data System (ADS)

Liao, Jian-Xiang; Chen, Guan-Ming; Chiou, Ming-Da; Jan, Sen; Wei, Chih-Lin

2017-07-01

Submarine canyons are major conduits of terrestrial and shelf organic matter, potentially benefiting the seafloor communities in the food-deprived deep sea; however, strong bottom currents driven by internal tides and the potentially frequent turbidity currents triggered by storm surges, river flooding, and earthquakes may negatively impact the benthos. In this study, we investigated the upper Gaoping Submarine Canyon (GPSC), a high-sediment-yield canyon connected to a small mountain river (SMR) off southwest (SW) Taiwan. By contrasting the benthic meiofaunal and macrofaunal communities within and outside the GPSC, we examined how food supplies and disturbance influenced the benthic community assemblages. The benthic communities in the upper GPSC were mainly a nested subset of the adjacent slope assemblages. Several meiofaunal (e.g. ostracods) and macrofaunal taxa (e.g. peracarid crustaceans and mollusks) that typically occurred on the slope were lost from the canyon. The polychaete families switched from diverse feeding guilds on the slope to motile subsurface deposit feeders dominant in the canyon. The diminishing of epibenthic peracarids and proliferation of deep burrowing polychaetes in the GPSC resulted in macrofauna occurring largely within deeper sediment horizons in the canyon than on the slope. The densities and numbers of taxa were depressed with distinct and more variable composition in the canyon than on the adjacent slope. Both the densities and numbers of taxa were negatively influenced by internal tide flushing and positively influenced by food availability; however, the internal tides also negatively influenced the food supplies. While the meiofauna and macrofauna densities were both depressed by the extreme physical conditions in the GPSC, only the macrofaunal densities increased with depth in the canyon, presumably related to increased frequency and intensity of disturbance toward the canyon head. The population densities of meiofauna, on the

75 FR 39147 - Establishment of Class E Airspace; Bryce Canyon, UT

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-08

... E airspace at Bryce Canyon, UT, to accommodate aircraft using a new Area Navigation (RNAV) Global Positioning System (GPS) Standard Instrument Approach Procedures (SIAPs) at Bryce Canyon Airport. This will improve the safety and management of Instrument Flight Rules (IFR) operations at the airport. DATES...

Turbulent Transfer Between Street Canyons and the Overlying Atmospheric Boundary Layer

NASA Astrophysics Data System (ADS)

Salizzoni, Pietro; Marro, Massimo; Soulhac, Lionel; Grosjean, Nathalie; Perkins, Richard J.

2011-12-01

The turbulent exchange of momentum between a two-dimensional cavity and the overlying boundary layer has been studied experimentally, using hot-wire anemometry and particle image velocimetry (PIV). Conditions within the boundary layer were varied by changing the width of the canyons upstream of the test canyon, whilst maintaining the square geometry of the test canyon. The results show that turbulent transfer is due to the coupling between the instabilities generated in the shear layer above the canyons and the turbulent structures in the oncoming boundary layer. As a result, there is no single, unique velocity scale that correctly characterizes all the processes involved in the turbulent exchange of momentum across the boundary layer. Similarly, there is no single velocity scale that can characterize the different properties of the turbulent flow within the canyon, which depends strongly on the way in which turbulence from the outer flow is entrained into the cavity and carried round by the mean flow. The results from this study will be useful in developing simple parametrizations for momentum exchange in the urban canopy, in situations where the street geometry consists principally of relatively long, uniform streets arranged in grid-like patterns; they are unlikely to be applicable to sparse geometries composed of isolated three-dimensional obstacles.

Environmental and human impact on the sedimentary dynamic in the Rhone Delta subaquatic canyons (France-Switzerland)

NASA Astrophysics Data System (ADS)

Arantegui, A.; Corella, J. P.; Loizeau, J. L.; Anselmetti, F. S.; Girardclos, S.

2012-04-01

Deltas are very sensitive environments and highly vulnerable to variations in water discharge and the amount of suspended sediment load provided by the delta-forming currents. Human activities in the watershed, such as building of dams and irrigation ditches, or river bed deviations, may affect the discharge regime and sediment input, thus affecting delta growth. Underwater currents create deeply incised canyons cutting into the delta lobes. Understanding the sedimentary processes in these subaquatic canyons is crucial to reconstruct the fluvial evolution and human impact on deltaic environments and to carry out a geological risk assessment related to mass movements, which may affect underwater structures and civil infractructure. Recently acquired high-resolution multibeam bathymetry on the Rhone Delta in Lake Geneva (Sastre et al. 2010) revealed the complexity of the underwater morphology formed by active and inactive canyons first described by Forel (1892). In order to unravel the sedimentary processes and sedimentary evolution in these canyons, 27 sediment cores were retrieved in the distal part of each canyon and in the canyon floor/levee complex of the active canyon. Geophysical, sedimentological, geochemical and radiometric dating techniques were applied to analyse these cores. Preliminary data show that only the canyon originating at the current river mouth is active nowadays, while the others remain inactive since engineering works in the watershed occurred, confirming Sastre et al. (2010). However, alternating hemipelagic and turbiditic deposits on the easternmost canyons, evidence underflow processes during the last decades as well. Two canyons, which are located close to the Rhone river mouth, correspond to particularly interesting deeply incised crevasse channels formed when the underwater current broke through the outer bend of a meander in the proximal northern levee. In these canyons, turbidites occur in the sediment record indicating ongoing

Small-scale turbidity currents in a big submarine canyon

USGS Publications Warehouse

Xu, Jingping; Barry, James P.; Paull, Charles K.

2013-01-01

Field measurements of oceanic turbidity currents, especially diluted currents, are extremely rare. We present a dilute turbidity current recorded by instrumented moorings 14.5 km apart at 1300 and 1860 m water depth. The sediment concentration within the flow was 0.017%, accounting for 18 cm/s gravity current speed due to density excess. Tidal currents of ∼30 cm/s during the event provided a "tailwind" that assisted the down-canyon movement of the turbidity current and its sediment plume. High-resolution velocity measurements suggested that the turbidity current was likely the result of a local canyon wall slumping near the 1300 m mooring. Frequent occurrences, in both space and time, of such weak sediment transport events could be an important mechanism to cascade sediment and other particles, and to help sustain the vibrant ecosystems in deep-sea canyons.

A Predictive Model for Submarine Canyon Type Based on the Relative Influence of Rivers, Waves and Tides.

NASA Astrophysics Data System (ADS)

Sumner, E.; Paull, C. K.

2017-12-01

In recent years progress has been achieved in directly measuring turbidity currents in submarine canyons and channels. It is useful to consider how representative these observations are of the diversity that potentially exists in the dynamics of turbidity currents among different canyons and channels. Firstly, we integrate sediment core, bathymetric and (in a limited number of cases) direct observations of turbidity current dynamics from 20 submarine canyons on the northern California Margin. We use this dataset to construct a diagram that explains canyon type, and thus turbidity current characteristics (grain-size carried, flow power, relative frequency of flows), based on the relative influence of rivers, waves and tides at the canyon head. This diagram enables prediction of canyon type and thus processes using three easily measurable characteristics: (i) distance of the canyon head from the shoreline; (ii) distance of the canyon head from the nearest river mouth; and (iii) local shelf width. Secondly, we test and refine the diagram using published data on submarine canyons from around the world. We also discuss the influence of outsized events such as earthquakes on submarine canyons. Finally, we demonstrate the location within the diagram of current monitoring studies and thus suggest where it might be fruitful to focus future monitoring efforts.

Megafauna of vulnerable marine ecosystems in French mediterranean submarine canyons: Spatial distribution and anthropogenic impacts

NASA Astrophysics Data System (ADS)

Fabri, M.-C.; Pedel, L.; Beuck, L.; Galgani, F.; Hebbeln, D.; Freiwald, A.

2014-06-01

Vulnerable Marine Ecosystems (VME) in the deep Mediterranean Sea have been identified by the General Fisheries Commission for the Mediterranean as consisting of communities of Scleractinia (Lophelia pertusa and Madrepora oculata), Pennatulacea (Funiculina quadrangularis) and Alcyonacea (Isidella elongata). This paper deals with video data recorded in the heads of French Mediterranean canyons. Quantitative observations were extracted from 101 video films recorded during the MEDSEACAN cruise in 2009 (Aamp/Comex). Qualitative information was extracted from four other cruises (two Marum/Comex cruises in 2009 and 2011 and two Ifremer cruises in 1995 and 2010) to support the previous observations in the Cassidaigne and Lacaze-Duthiers canyons. All the species, fishing impacts and litter recognized in the video films recorded from 180 to 700 m depth were mapped using GIS. The abundances and distributions of benthic fishing resources (marketable fishes, Aristeidae, Octopodidae), Vulnerable Marine Species, trawling scars and litter of 17 canyons were calculated and compared, as was the open slope between the Stoechades and Toulon canyons. Funiculina quadrangularis was rarely observed, being confined for the most part to the Marti canyon and, I. elongata was abundant in three canyons (Bourcart, Marti, Petit-Rhône). These two cnidarians were encountered in relatively low abundances, and it may be that they have been swept away by repeated trawling. The Lacaze-Duthiers and Cassidaigne canyons comprised the highest densities and largest colony sizes of scleractinian cold-water corals, whose distribution was mapped in detail. These colonies were often seen to be entangled in fishing lines. The alcyonacean Callogorgia verticillata was observed to be highly abundant in the Bourcart canyon and less abundant in several other canyons. This alcyonacean was also severely affected by bottom fishing gears and is proposed as a Vulnerable Marine Species. Our studies on anthropogenic

BLANCO MOUNTAIN AND BLACK CANYON ROADLESS AREAS, CALIFORNIA.

USGS Publications Warehouse

Diggles, Michael F.; Rains, Richard L.

1984-01-01

The mineral survey of the Blanco Mountain and Black Canyon Roadless Areas, California indicated that areas of probable and substantiated mineral-resource potential exist only in the Black Canyon Roadless Area. Gold with moderate amounts of lead, silver, zinc, and tungsten, occurs in vein deposits and in tactite. The nature of the geological terrain indicates little likelihood for the occurrence of energy resources in the roadless areas. Detailed geologic mapping might better define the extent of gold mineralization. Detailed stream-sediment sampling and analysis of heavy-mineral concentrations could better define tungsten resource potential.

A Laboratory model for the flow in urban street canyons induced by bottom heating

NASA Astrophysics Data System (ADS)

Liu, Huizhi; Liang, Bin; Zhu, Fengrong; Zhang, Boyin; Sang, Jianguo

2003-07-01

Water tank experiments are carried out to investigate the convection flow induced by bottom heating and the effects of the ambient wind on the flow in non-symmetrical urban street canyons based on the PIV (Particle Image Visualization) technique. Fluid experiments show that with calm ambient wind, the flows in the street canyon are completely driven by thermal force, and the convection can reach the upper atmosphere of the street canyon. Horizontal and vertical motions also appear above the roofs of the buildings. These are the conditions which favor the exchange of momentum and air mass between the street canyon and its environment. More than two vortices are induced by the convection, and the complex circulation pattern will vary with time in a wider street canyon. However, in a narrow street canyon, just one vortex appears. With a light ambient wind, the bottom heating and the associated convection result in just one main vortex. As the ambient wind speed increases, the vortex becomes more organized and its center shifts closer to the leeward building.

Distributions and habitat associations of deep-water corals in Norfolk and Baltimore Canyons, Mid-Atlantic Bight, USA

NASA Astrophysics Data System (ADS)

Brooke, S. D.; Watts, M. W.; Heil, A. D.; Rhode, M.; Mienis, F.; Duineveld, G. C. A.; Davies, A. J.; Ross, S. W.

2017-03-01

A multi-disciplinary study of two major submarine canyons, Baltimore Canyon and Norfolk Canyon, off the US mid-Atlantic coast focused on the ecology and biology of canyon habitats, particularly those supporting deep-sea corals. Historical data on deep-sea corals from these canyons were sparse with less than 750 records for the mid-Atlantic region, with most being soft sediment species. This study substantially increased the number of deep-sea coral records for the target canyons and the region. Large gorgonians were the dominant structure-forming coral taxa on exposed hard substrates, but several species of scleractinians were also documented, including first observations of Lophelia pertusa in the mid-Atlantic Bight region. Coral distribution varied within and between the two canyons, with greater abundance of the octocoral Paragorgia arborea in Baltimore Canyon, and higher occurrence of stony corals in Norfolk Canyon; these observations reflect the differences in environmental conditions, particularly turbidity, between the canyons. Some species have a wide distribution (e.g., P. arborea, Primnoa resedaeformis, Anthothela grandiflora), while others are limited to certain habitat types and/or depth zones (e.g., Paramuricea placomus, L. pertusa, Solenosmilia variabilis). The distribution of a species is driven by a combination of factors, which include availability of appropriate physical structure and environmental conditions. Although the diversity of the structure-forming corals (gorgonians, branching scleractinians and large anemones) was low, many areas of both canyons supported high coral abundance and a diverse coral-associated community. The canyons provide suitable habitat for the development of deep-sea coral communities that is not readily available elsewhere on the sedimented shelf and slope of the Mid-Atlantic Bight.

Geology and geomorphology of the Lower Deschutes River Canyon, Oregon.

Treesearch

Robin A. Beebee; Jim E. O' Connor; Gordon E. Grant

2002-01-01

This field guide is designed for geologists floating the approximately 80 kilometers (50 miles) of the Deschutes River from the Pelton-Round Butte Dam Complex west of Madras to Maupin, Oregon. The first section of the guide is a geologic timeline tracing the formation of the units that compose the canyon walls and the incision of the present canyon. The second section...

Canyons and Mesas of Aureum Chaos

NASA Image and Video Library

2002-06-26

This image from NASA Mars Odyssey shows a portion of Aureum Chaos located just south of the Martian equator. This fractured landscape contains canyons and mesas with two large impact craters in the upper left.

Environmental analysis of Acid/middle Pueblo Canyon, Los Alamos, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.

1982-08-01

The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, and Pueblo Canyon found residual radioactivity at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons, all the way to the Rio Grande. The largest reservoir of radioactive material is in lower Pueblo Canyon, which is on DOE property. The only areas where residual radioactivity exceeds the proposed cleanup criteria are at the former vehicle decontamination facility, located between the former treatment plant site and Acid Canyon, around the former untreated waste outfall and for a short distancemore » below, and in two small areas farther down in Acid Canyon. The three alternatives proposed are (1) to take no action, (2) to fence the areas where the residual radioactivity exceeds the proposed criteria (minimal action), and (3) to clean up the former vehicle decontamination facility and around the former untreated waste outfall. Calculations based on actual measurements indicate that the annual dose at the location having the greatest residual radioactivity would be about 12% of the applicable guideline. Most doses are much smaller than that. No environmental impacts are associated with either the no-action or minimal action alternatives. The impact associated with the cleanup alternative is very small. The preferred alternative is to clean up the areas around the former vehicle decontamination facility and the untreated waste outfall. This course of action is recommended not because of any real danger associated with the residual radioactivity, but rather because the cleanup operation is a minor effort and would conform with the ALARA (as low as reasonably achievable) philosophy.« less

Morphology and sediment dynamics of the Capbreton canyon (Bay of Biscay, SW France)

NASA Astrophysics Data System (ADS)

Gaudin, M.; Umr 5805; Ifremer Team

2003-04-01

The Canyon of Capbreton extending in the Bay of Biscay (SW France) is the deepest canyon in the world. Its structure and morphology was studied using new multibeam bathymetry, acoustic imagery and high-resolution seismic data. The canyon head appears only 250 m away from the coast line and runs westward parallel to the north coast of Spain for 160 km due to structural control, then turns northward, widens and abruptly disappears in the continental rise by 3500 m water depth. Its northern margin is flat and progrades clearly westward. Conversely the southern margin is steep and progrades towards the north (i.e. towards the canyon). Down to 800 m water depth, the canyon deeply incises the continental shelf and the axial channel is meandering (sinuosity of 1.9). The canyon shows both major and minor stream beds, perched tributary valleys, nested terraces and abandoned meanders. The terraces have three morphologies: (1) flat, (2) with a raised side or (3) with a horseshoe structure. These morphologies have been interpreted as overbank deposits or nested levees (1 and 2) or as the result of meander abandon (3). Terraces of types (1) and (2) contain mainly fine deposits resulting from decantation of the top of turbulent surges that flow in the canyon. Westward (800 to 2000 m water depth) the main talweg remains sinuous (1.7). On the southern margin, several straight or slightly sinuous S-N tributary valleys are followed by alignments of pockmarks that also indicate a structural control. On the northern margin, a single large tributary valley with a sinuous central talweg, flowing from the upper Aquitaine continental slope, is interpreted as a giant slump scar due to sediment instability. This valley is bordered to the west by a topographic high with sediment waves on the external flank that might be interpreted as a sedimentary levee. The canyon recorded a recent turbidite activity. An 18 cm-thick turbidite was deposited at 650 m water depth by a turbidity current

A sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change

USGS Publications Warehouse

Grams, Paul E.

2013-01-01

Recent U.S. Geological Survey research is providing important insights into how best to monitor changes in the amount of tributary-derived sand stored on the bed of the Colorado River and in eddies in Marble Canyon, Arizona. Before the construction of Glen Canyon Dam and other dams upstream, sandbars in Glen, Marble, and Grand Canyons were replenished each year by sediment-rich floods. Sand input into the Colorado River is crucial to protecting endangered native fish, animals, and plants and cultural and recreational resources along the river in Glen Canyon National Recreation Area and Grand Canyon National Park.

Impact of building configuration on air quality in street canyon

NASA Astrophysics Data System (ADS)

Xie, Xiaomin; Huang, Zhen; Wang, Jia-song

The objective of this study is to provide a simulation of emissions from vehicle exhausts in a street canyon within an urban environment. Standard, RNG and Chen-Kim k- ɛ turbulence models are compared with the wind tunnel measured data for optimization of turbulence model. In the first approach, the investigation is made into the effect of the different roof shapes and ambient building structures. The results indicate that the in-canyon vortex dynamics (e.g. vortex orientation) and the characteristics of pollutant dispersion are dependent on the roof shapes and ambient building structures strongly. A second set of calculations for a three-dimensional simulation of the street canyon setup was performed to investigate the influence of building geometry on pollutant dispersion. The validation of the numerical model was evaluated using an extensive experimental database obtained from the atmospheric boundary layer wind tunnel at the Meteorological Institute of Hamburg University, Germany (Studie on different roof geometries in a simplified urban environment, 1995). The studies give evidence that roof shapes, the ambient building configurations and building geometries are important factors determining the flow patterns and pollutant dispersion in street canyon.

On the pollutant removal, dispersion, and entrainment over two-dimensional idealized street canyons

NASA Astrophysics Data System (ADS)

Liu, Chun-Ho; Wong, Colman C. C.

2014-01-01

Pollutant dispersion over urban areas is not that well understood, in particular at the street canyon scale. This study is therefore conceived to examine how urban morphology modifies the pollutant removal, dispersion, and entrainment over urban areas. An idealized computational domain consisting of 12 two-dimensional (2D) identical street canyons of unity aspect ratio is employed. The large-eddy simulation (LES) is used to calculate the turbulent flows and pollutant transport in the urban boundary layer (UBL). An area source of uniform pollutant concentration is applied on the ground of the first street canyon. A close examination on the roof-level turbulence reveals patches of low-speed air masses in the streamwise flows and narrow high-speed downdrafts in the shear layer. Different from the flows over a smooth surface, the turbulence intensities are peaked near the top of the building roughness. The pollutant is rather uniformly distributed inside a street canyon but disperses quickly in the UBL over the buildings. Partitioning the vertical pollutant flux into its mean and turbulent components demystifies that the pollutant removal is mainly governed by turbulence. Whereas, mean wind carries pollutant into and out of a street canyon simultaneously. In addition to wind speed promotion, turbulent mixing is thus required to dilute the ground-level pollutants, which are then removed from the street canyon to the UBL. Atmospheric flows slow down rapidly after the leeward buildings, leading to updrafts carrying pollutants away from the street canyons (the basic pollutant removal mechanism).

Software Configuration Management Plan for the B-Plant Canyon Ventilation Control System

DOE Office of Scientific and Technical Information (OSTI.GOV)

MCDANIEL, K.S.

1999-08-31

Project W-059 installed a new B Plant Canyon Ventilation System. Monitoring and control of the system is implemented by the Canyon Ventilation Control System (CVCS). This Software Configuration Management Plan provides instructions for change control of the CVCS.

Precipitation variability of the Grand Canyon region, 1893 through 2009, and its implications for studying effects of gullying of Holocene terraces and associated archeological sites in Grand Canyon, Arizona

USGS Publications Warehouse

Hereford, Richard; Bennett, Glenn E.; Fairley, Helen C.

2014-01-01

A daily precipitation dataset covering a large part of the American Southwest was compiled for online electronic distribution (http://pubs.usgs.gov/of/2014/1006/). The dataset contains 10.8 million observations spanning January 1893 through January 2009 from 846 weather stations in six states and 13 climate divisions. In addition to processing the data for distribution, water-year totals and other statistical parameters were calculated for each station with more than 2 years of observations. Division-wide total precipitation, expressed as the average deviation from the individual station means of a climate division, shows that the region—including the Grand Canyon, Arizona, area—has been affected by alternating multidecadal episodes of drought and wet conditions. In addition to compiling and analyzing the long-term regional precipitation data, a second dataset consisting of high-temporal-resolution precipitation measurements collected between November 2003 and January 2009 from 10 localities along the Colorado River in Grand Canyon was compiled. An exploratory study of these high-temporal-resolution precipitation measurements suggests that on a daily basis precipitation patterns are generally similar to those at a long-term weather station in the canyon, which in turn resembles the patterns at other long-term stations on the canyon rims; however, precipitation amounts recorded by the individual inner canyon weather stations can vary substantially from station to station. Daily and seasonal rainfall patterns apparent in these data are not random. For example, the inner canyon record, although short and fragmented, reveals three episodes of widespread, heavy precipitation in late summer 2004, early winter 2005, and summer 2007. The 2004 event and several others had sufficient rainfall to initiate potentially pervasive erosion of the late Holocene terraces and related archeological features located along the Colorado River in Grand Canyon.

A paleolimnological investigation of historical environmental change in East Canyon Reservoir

NASA Astrophysics Data System (ADS)

Higby Halseth, Deanna Renee

East Canyon Reservoir is located 32 km east of Salt Lake City, Utah, and serves as a resource for irrigation, culinary water, and recreation. This research used paleolimnology and historical records to investigate the impacts of multiple stressors, including land clearance, dam construction and enlargement, and climate warming on East Canyon Reservoir. Recently, blue green algal blooms, typically indicative of eutrophication, have been increasing at East Canyon Reservoir despite reductions of nutrients from point sources, so part of the impetus for this study was to understand the forcing mechanisms of these blooms. A multiproxy analysis of three sediment cores retrieved from the reservoir determined changes in nutrient concentrations and sediment composition over time. Percent organics, magnetic susceptibility, and diatom analyses of 210Pb dated cores were compared to measurements of temperature and precipitation as well as records of historical land use, which were determined using remote sensing. Percent organics and magnetic susceptibility showed changes related to dam construction and increased development. Fossil diatom assemblages indicated that East Canyon Reservoir had been eutrophic since origination; however, principal components analyses of the diatom data indicated that the canyon became more P-enriched following dam construction and increased development. Recent increases in Cyclotella diatoms indicate changes related to warming temperatures, and we speculate that this warming is also what is causing blue-green algal blooms to increase.

Numerical modeling of the late Cenozoic geomorphic evolution of Grand Canyon, Arizona

NASA Astrophysics Data System (ADS)

Pelletier, J. D.

2008-12-01

The late Cenozoic geomorphic evolution of Grand Canyon has been influenced by three primary tectonic and drainage adjustment events. First, incision into the Paleozoic strata of the southwestern margin of the Colorado Plateau began at 16 Ma in response to relief production along the Grand Wash Fault. Second, the ancestral Upper Colorado River reversed drainage and became integrated with the Lower Colorado River basin through Grand Canyon between 5.5 and 6 Ma. Third, the Colorado River was influenced by Plio- Quaternary normal faulting along the Hurricane and Toroweap Faults. Despite the relatively firm constraints available on the timing of these events, the geomorphic evolution of Grand Canyon is still not well constrained and many questions remain. For example, was there a deeply-incised gorge in western Grand Canyon before Colorado River integration? How and where was the Colorado River integrated? How have incision rates varied in space and time? In this paper, I describe the results of a numerical modeling study designed to address these questions. The model integrates the stream power model for bedrock channel erosion with cliff retreat and the flexural-isostatic response to erosion. The model honors the structural geology of the Grand Canyon region, including the variable erodibility of rocks in the Colorado Plateau and the occurrence of Plio-Quaternary normal faulting along the Hurricane-Toroweap Fault system. We present the results of two models designed to bracket the possible drainage architectures of the southwestern margin of the Colorado Plateau in Miocene time. In the first model, we assume a 13,000 km2 drainage basin primarily sourced from the Hualapai and Coconino Plateaux. The results of this model indicate that relief production along the Grand Wash fault initiated the formation of a large (700 m) knickpoint that migrated headward at a rate of 15 km/Myr prior to drainage integration at 6 Ma to form a deep gorge in western Grand Canyon. This model

75 FR 44809 - Glen Canyon Dam Adaptive Management Work Group (AMWG)

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-29

... Canyon Dam Adaptive Management Program (AMP) was implemented as a result of the Record of Decision on the... of the Grand Canyon Protection Act (Pub. L. 102-575) of 1992. The AMP includes a Federal advisory... other administrative and resource issues pertaining to the AMP. To view a copy of the agenda and...

75 FR 439 - Glen Canyon Dam Adaptive Management Work Group (AMWG)

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-05

... Canyon Dam Adaptive Management Program (AMP) was implemented as a result of the Record of Decision on the... of the Grand Canyon Protection Act (Pub. L. 102-575) of 1992. The AMP includes a Federal advisory... addition, other administrative and resource issues pertaining to the AMP may be discussed as necessary. To...

Mapping the True 3D Morphology of Deep-Sea Canyons

NASA Astrophysics Data System (ADS)

Huvenne, V. A.; Masson, D.; Tyler, P. A.; Huehnerbach, V.

2010-12-01

The importance of submarine canyons as ecosystem hotspots and sediment transport pathways has been recognised for decades (e.g. Heezen et al., 1955; Vetter & Dayton, 1998). However, studying canyon systems in detail is a challenge, because of the complexity and steepness of the terrain. Acoustic surveys are hampered by side-echoes, while the high slope angles cause most types of sampling equipment, deployed from surface vessels, to fail. Ship-borne bathymetric surveys tend to represent the canyon topography in an overly smoothed way as a result of their limited resolution in deep water compared to the scale of the terrain variability. Moreover, it is clear that overhanging cliffs cannot be mapped correctly with traditional, downward looking multibeam echosounders. The increasing availability of underwater vehicles, however, opens new opportunities. During summer 2009, we mapped several submarine canyon habitats in detail, using the UK deep-water Remotely Operated Vehicle (ROV) ISIS. In particular, we developed a new methodology to map vertical cliffs and overhangs by placing the high-resolution Simrad SM2000 multibeam system of the ROV in a forward-looking position rather than in the traditional downward-looking configuration. The cliff morphology was then mapped by moving the ROV laterally in parallel passes at different depths. Repeating this approach at different distances from the cliff face, we obtained maps of varying resolution and extent. The low resolution maps provide an overview of the general geological framework, while individual strata and faunal colonies can be recognised on the highest resolution maps. Using point-cloud models, we combined the ship-borne bathymetry with the ROV-based data, in order to obtain a true 3D seabed morphology of the canyon study site, which can be used for fly-throughs, geomorphological analysis or habitat mapping. With this approach, we could visualise the spatial structure and density distribution of a unique and

Grand Canyon Similar to Mount Sharp

NASA Image and Video Library

2012-08-27

Before NASA Curiosity rover landed on Mars, the strata exposed in Mount Sharp were compared to those in the Grand Canyon of the western United States, shown here. Scientists are surprised by just how close the similarities are.

Earthquakes drive large-scale submarine canyon development and sediment supply to deep-ocean basins.

PubMed

Mountjoy, Joshu J; Howarth, Jamie D; Orpin, Alan R; Barnes, Philip M; Bowden, David A; Rowden, Ashley A; Schimel, Alexandre C G; Holden, Caroline; Horgan, Huw J; Nodder, Scott D; Patton, Jason R; Lamarche, Geoffroy; Gerstenberger, Matthew; Micallef, Aaron; Pallentin, Arne; Kane, Tim

2018-03-01

Although the global flux of sediment and carbon from land to the coastal ocean is well known, the volume of material that reaches the deep ocean-the ultimate sink-and the mechanisms by which it is transferred are poorly documented. Using a globally unique data set of repeat seafloor measurements and samples, we show that the moment magnitude ( M w ) 7.8 November 2016 Kaikōura earthquake (New Zealand) triggered widespread landslides in a submarine canyon, causing a powerful "canyon flushing" event and turbidity current that traveled >680 km along one of the world's longest deep-sea channels. These observations provide the first quantification of seafloor landscape change and large-scale sediment transport associated with an earthquake-triggered full canyon flushing event. The calculated interevent time of ~140 years indicates a canyon incision rate of 40 mm year -1 , substantially higher than that of most terrestrial rivers, while synchronously transferring large volumes of sediment [850 metric megatons (Mt)] and organic carbon (7 Mt) to the deep ocean. These observations demonstrate that earthquake-triggered canyon flushing is a primary driver of submarine canyon development and material transfer from active continental margins to the deep ocean.

Earthquakes drive large-scale submarine canyon development and sediment supply to deep-ocean basins

PubMed Central

Mountjoy, Joshu J.; Howarth, Jamie D.; Orpin, Alan R.; Barnes, Philip M.; Bowden, David A.; Rowden, Ashley A.; Schimel, Alexandre C. G.; Holden, Caroline; Horgan, Huw J.; Nodder, Scott D.; Patton, Jason R.; Lamarche, Geoffroy; Gerstenberger, Matthew; Micallef, Aaron; Pallentin, Arne; Kane, Tim

2018-01-01

Although the global flux of sediment and carbon from land to the coastal ocean is well known, the volume of material that reaches the deep ocean—the ultimate sink—and the mechanisms by which it is transferred are poorly documented. Using a globally unique data set of repeat seafloor measurements and samples, we show that the moment magnitude (Mw) 7.8 November 2016 Kaikōura earthquake (New Zealand) triggered widespread landslides in a submarine canyon, causing a powerful “canyon flushing” event and turbidity current that traveled >680 km along one of the world’s longest deep-sea channels. These observations provide the first quantification of seafloor landscape change and large-scale sediment transport associated with an earthquake-triggered full canyon flushing event. The calculated interevent time of ~140 years indicates a canyon incision rate of 40 mm year−1, substantially higher than that of most terrestrial rivers, while synchronously transferring large volumes of sediment [850 metric megatons (Mt)] and organic carbon (7 Mt) to the deep ocean. These observations demonstrate that earthquake-triggered canyon flushing is a primary driver of submarine canyon development and material transfer from active continental margins to the deep ocean. PMID:29546245

Recent sediment studies refute Glen Canyon Dam hypothesis

USGS Publications Warehouse

Rubin, David M.; Topping, David J.; Schmidt, John C.; Hazel, Joe; Kaplinski, Matt; Melis, Theodore S.

2002-01-01

Recent studies of sedimentology hydrology, and geomorphology indicate that releases from Glen Canyon Dam are continuing to erode sandbars and beaches in the Colorado River in Grand Canyon National Park, despite attempts to restore these resources. The current strategy for dam operations is based on the hypothesis that sand supplied by tributaries of the Colorado River downstream from the dam will accumulate in the channel during normal dam operations and remain available for restoration floods. Recent work has shown that this hypothesis is false, and that tributary sand inputs are exported downstream rapidly typically within weeks or months under the current flow regime.

A Spacebird-eye View of the Grand Canyon from NASA Terra Spacecraft

NASA Image and Video Library

2011-10-14

NASA Terra spacecraft provided this view of the eastern part of Grand Canyon National Park in northern Arizona in this image on July 14, 2011. This view looks to the west, with tourist facilities of Grand Canyon Village visible in the upper left.

Mud Volcanism in a Canyon: Morphodynamic Evolution of the Active Venere Mud Volcano and Its Interplay With Squillace Canyon, Central Mediterranean

NASA Astrophysics Data System (ADS)

Loher, Markus; Ceramicola, Silvia; Wintersteller, Paul; Meinecke, Gerrit; Sahling, Heiko; Bohrmann, Gerhard

2018-02-01

Submarine mud volcanoes develop through the extrusion of methane-rich fluids and sediments onto the seafloor. The morphology of a mud volcano can record its extrusive history and processes of erosion and deformation affecting it. The study of offshore mud volcano dynamics is limited because only few have been mapped at resolutions that reveal their detailed surface structures. More importantly, rates and volumes of extruded sediment and methane are poorly constrained. The 100 m high twin cones of Venere mud volcano are situated at ˜1,600 m water depth within Squillace Canyon along the Ionian Calabrian margin, Mediterranean Sea. Seafloor bathymetry and backscatter data obtained by a ship-based system and an autonomous underwater vehicle (AUV) allow mapping of mudflow deposits of the mud volcano and bedforms in the surrounding canyon. Repeated surveying by AUV document active mud movement at the western summit in between 2014 and 2016. Through sediment coring and tephrochronology, ages of buried mudflow deposits are determined based on the sedimentation rate and the thickness of overlying hemipelagic sediments. An average extrusion rate of 27,000 m3/yr over the last ˜882 years is estimated. These results support a three-stage evolutionary model of Venere mud volcano since ˜4,000 years ago. It includes the onset of quiescence at the eastern cone (after ˜2,200 years ago), erosive events in Squillace Canyon (prior to ˜882 years ago), and mudflows from the eastern cone (since ˜882 years). This study reveals new interactions between a mud volcano and a canyon in the deep sea.

Mixing and phytoplankton dynamics in a submarine canyon in the West Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Carvalho, Filipa; Kohut, Josh; Oliver, Matthew J.; Sherrell, Robert M.; Schofield, Oscar

2016-07-01

Bathymetric depressions (canyons) exist along the West Antarctic Peninsula shelf and have been linked with increased phytoplankton biomass and sustained penguin colonies. However, the physical mechanisms driving this enhanced biomass are not well understood. Using a Slocum glider data set with over 25,000 water column profiles, we evaluate the relationship between mixed layer depth (MLD, estimated using the depth of maximum buoyancy frequency) and phytoplankton vertical distribution. We use the glider deployments in the Palmer Deep region to examine seasonal and across canyon variability. Throughout the season, the ML becomes warmer and saltier, as a result of vertical mixing and advection. Shallow ML and increased stratification due to sea ice melt are linked to higher chlorophyll concentrations. Deeper mixed layers, resulting from increased wind forcing, show decreased chlorophyll, suggesting the importance of light in regulating phytoplankton productivity. Spatial variations were found in the canyon head region where local physical water column properties were associated with different biological responses, reinforcing the importance of local canyon circulation in regulating phytoplankton distribution in the region. While the mechanism initially hypothesized to produce the observed increases in phytoplankton over the canyons was the intrusion of warm, nutrient enriched modified Upper Circumpolar Deep Water (mUCDW), our analysis suggests that ML dynamics are key to increased primary production over submarine canyons in the WAP.

A Numerical Study on the Effects of Street‒canyon Aspect‒ratio on Reactive Pollutant Dispersion

NASA Astrophysics Data System (ADS)

Park, S. J.; Kim, J.

2014-12-01

In this study, the effects of street‒canyon aspect‒ratio on reactive pollutant dispersion were investigated using the coupled CFD‒chemistry model. For this, flow characteristics were analyzed first in street canyons with different aspect ratios and flow regimes were classified according to the building height. For each flow regime, dispersion characteristics were investigated in views of reactive pollutant concentration and VOCs‒NOX ratio. Finally, the relations between pollutant concentration and aspect ratio in urban street canyons were investigated. In the case of H/S = 1.0 (H is building height and S is street width), one clockwise‒rotating vortex appeared vertically and the reverse and outward flows were dominant near the street bottom. In the case of H/S = 2.0, two counter‒rotating vortices appeared vertically in the street canyon. The primary (secondary) vortex rotating clockwise (counterclockwise) was formed in upper (lower) layer. The flow patterns affected the reactive pollutant concentration in street canyons. As building height increased, mean concentration of NO decreased when one vortex was generated in street canyons and increased when two vortexes appeared in street canyons. O3 concentration showed almost contrasted tendency with those of NO because O3 was depleted by the NO titration.

Vegetative communities, Davis and Lavender Canyons, Paradox Basin, Utah: ecosystem studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1983-04-01

The major vegetative communities of Davis and Lavender canyons located in southeastern Utah are characterized. The report identifies potential secondary impacts and appropriate mitigation options. The Davis Canyon and Lavender Canyon Study Area contains nine major vegetative communities: galleta-shadscale, juniper-blackbrush, juniper-shadscale-ephedra, shadscale-ephedra, grayia-shadscale, juniper, drywash, greasewood, and riparian. The natural recovery times of these communities are exceedingly long. Natural reinvasion of various species would take from 15 to 100 years. No threatened or endangered plant species were identified in the study area. Davis and Lavender canyons have been subject to off-road vehicle activity and extensive grazing. The plant communities maymore » be subject to additional impacts as a result of increased human activity and off-highway activities such as camping, hiking, and hunting could result in changes in cover, composition, and frequency of plant species. Mitigation options for potential impacts include shuttle-busing workers to the site from the highway and fencing site access roads to prevent vehicles from leaving the roads.« less

High-Resolution Acoustic Imaging in the Agadir-Canyon Region, NW-Africa: Morphology, Processes and Geohazards

NASA Astrophysics Data System (ADS)

Krastel, S.; Wynn, R. B.; Feldens, P.; Unverricht, D.; Huehnerbach, V.; Stevenson, C.; Glogowski, S.; Schuerer, A.

2014-12-01

Agadir Canyon is one of the largest submarine canyons in the World, supplying giant submarine sediment gravity flows to the Agadir Basin and the wider Moroccan Turbidite System. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately after initial failure, is a major scientific challenge, which was addressed in the Agadir Canyon source region during Cruise MSM32. We collected ~ 1500 km of high-resolution seismic 2D-lines in combination with a dense net of hydroacoustic data. About 1000 km2 of sea floor were imaged during three deployments of TOBI (deep-towed sidescan sonar operated by the National Oceanography Centre Southampton). A total of 186 m of gravity cores and several giant box cores were recovered at more than 50 stations. The new data show that Agadir canyon is the source area of the world's largest submarine sediment flow, which occurred about 60,000 years ago. Up to 160 km3 of sediment was transported to the deep ocean in a single catastrophic event. For the first time, sediment flows of this scale have been tracked along their entire flow pathway. A major landslide area was identified south of Agadir Canyon. Landslide material enters Agadir canyon in about 2500 m water depth; the material is transported as debrite for at least another 200 km down the canyon. Initial data suggest that the last major slide from this source entered Agadir canyon at least 130,000 years ago. A large field of living deep-water corals was imaged north of Agadir canyon. To our knowledge, these are the first living cold water corals recovered off the coast of Morocco (except for the Gulf of Cadiz). They represent an important link between the known cold-water coral provinces off Mauritania and in the Gulf of Cádiz.

78 FR 2388 - Combined Notice of Filings #1

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-11

...-2401-002; ER10-2402-002; ER11- 3414-004; ER10-2403-002. Applicants: Blue Canyon Windpower LLC, Blue Canyon Windpower II LLC, Blue Canyon Windpower V LLC, Blue Canyon Windpower VI LLC, Cloud County Wind Farm, LLC. Description: Blue Canyon Windpower LLC, et al. submits Updated Market Power Analysis for...

Age and diet of fossil california condors in grand canyon, Arizona.

PubMed

Emslie, S D

1987-08-14

A dozen new radiocarbon dates, together with a thorough review of its fossil distribution, shed new light on the time and probable cause of extinction of the California condor, Gymnogyps californianus, in Grand Canyon, Arizona. The radiocarbon data indicate that this species became extinct in Grand Canyon, and other parts of the inland West, more than 10,000 years ago in coincidence with the extinction of megafauna (proboscidians, edentates, perissodactyls). That condors relied on the megafauna for food is suggested by the recovery of food bones from a late Pleistocene nest cave in Grand Canyon. These fossil data have relevance to proposed release and recovery programs of the present endangered population of California condors.

Colorado River fish monitoring in Grand Canyon, Arizona; 2000 to 2009 summary

USGS Publications Warehouse

Makinster, Andrew S.; Persons, William R.; Avery, Luke A.; Bunch, Aaron J.

2010-01-01

Long-term fish monitoring in the Colorado River below Glen Canyon Dam is an essential component of the Glen Canyon Dam Adaptive Management Program (GCDAMP). The GCDAMP is a federally authorized initiative to ensure that the primary mandate of the Grand Canyon Protection Act of 1992 to protect resources downstream from Glen Canyon Dam is met. The U.S. Geological Survey's Grand Canyon Monitoring and Research Center is responsible for the program's long-term fish monitoring, which is implemented in cooperation with the Arizona Game and Fish Department, U.S. Fish and Wildlife Service, SWCA Environmental Consultants, and others. Electrofishing and tagging protocols have been developed and implemented for standardized annual monitoring of Colorado River fishes since 2000. In 2009, sampling occurred throughout the river between Lees Ferry and Lake Mead for 38 nights over two trips. During the two trips, scientists captured 6,826 fish representing 11 species. Based on catch-per-unit-effort, salmonids (for example, rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta)) increased eightfold between 2006 and 2009. Flannelmouth sucker (Catostomus latipinnis) catch rates were twice as high in 2009 as in 2006. Humpback chub (Gila cypha) catches were low throughout the 10-year sampling period.

Large-Eddy Simulation of Flow and Pollutant Transport in Urban Street Canyons with Ground Heating

NASA Astrophysics Data System (ADS)

Li, Xian-Xiang; Britter, Rex E.; Koh, Tieh Yong; Norford, Leslie K.; Liu, Chun-Ho; Entekhabi, Dara; Leung, Dennis Y. C.

2010-11-01

Our study employed large-eddy simulation (LES) based on a one-equation subgrid-scale model to investigate the flow field and pollutant dispersion characteristics inside urban street canyons. Unstable thermal stratification was produced by heating the ground of the street canyon. Using the Boussinesq approximation, thermal buoyancy forces were taken into account in both the Navier-Stokes equations and the transport equation for subgrid-scale turbulent kinetic energy (TKE). The LESs were validated against experimental data obtained in wind-tunnel studies before the model was applied to study the detailed turbulence, temperature, and pollutant dispersion characteristics in the street canyon of aspect ratio 1. The effects of different Richardson numbers ( Ri) were investigated. The ground heating significantly enhanced mean flow, turbulence, and pollutant flux inside the street canyon, but weakened the shear at the roof level. The mean flow was observed to be no longer isolated from the free stream and fresh air could be entrained into the street canyon at the roof-level leeward corner. Weighed against higher temperature, the ground heating facilitated pollutant removal from the street canyon.

77 FR 8895 - Jimbilnan, Pinto Valley, Black Canyon, Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-15

..., Pinto Valley, Black Canyon, Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and Bridge Canyon..., Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and Bridge Canyon Wilderness Areas, Lake Mead... wilderness character; providing for reasonable use of Spirit Mountain and adjacent areas in a manner meeting...

77 FR 51022 - Clark Canyon Hydro, LLC; Notice of Application Accepted for Filing, Ready for Environmental...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-23

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 12429-007] Clark Canyon... b. Project No.: 12429-007. c. Date Filed: May 31, 2012. d. Applicant: Clark Canyon Hydro, LLC . e. Name of Project: Clark Canyon Dam Hydroelectric Project. f. Location: When constructed, the project...

New thermochronometric constraints on the Tertiary landscape evolution of the central and eastern Grand Canyon, Arizona

USGS Publications Warehouse

Lee, John P.; Stockli, Daniel F.; Kelley, S.A.; Pederson, J.; Karlstrom, K.E.; Ehlers, T.A.

2013-01-01

Thermal histories are modeled from new apatite (U-Th)/He and apatite fission-track data in order to quantitatively constrain the landscape evolution of the Grand Canyon region. Fifty new samples and their associated thermochronometric ages are presented here. Samples span from Lee’s Ferry in the east to Quartermaster Canyon in the west and include four age-elevation transects into Grand Canyon and borehole samples from the Coconino Plateau. Twenty-seven samples are inversely modeled to provide continuous thermal histories. This represents the most extensive and complete dataset on patterns of long-term exhumation in the Grand Canyon region, and it enables us to constrain the timing and magnitude of erosion and also discriminate between canyon incision and broader planation. The new data suggest that the early Cenozoic landscape in eastern Grand Canyon was low in relief and does not indicate the presence of an early Cenozoic precursor to the modern Grand Canyon. However, there is evidence for the incision of a smaller-scale canyon across the Kaibab Uplift at 28–20 Ma. This middle-Cenozoic denudation event was accompanied by the removal of a majority of remaining Mesozoic strata west of the Kaibab Uplift. In contrast, just upstream in the area of Lee’s Ferry, ∼2 km of Mesozoic strata remained over the middle Cenozoic and were removed after 10 Ma.

Mineral resources of the East Fork High Rock Canyon Wilderness Study Area, Washoe and Humboldt counties, Nevada

USGS Publications Warehouse

Ach, Jay A.; Plouff, Donald; Turner, R.L.; Schmauch, S.W.

1987-01-01

The part of the East Fork High Rock Canyon Wilderness Study Area (CA-020-914/NV-020-006A) included in this study encompasses 33,460 acres in the northwestern part of Nevada. Throughout this report, "wilderness study area" and "study area" refertothe 33,460 acres for which mineral surveys were requested. The U.S. Geological Survey and the U.S. Bureau of Mines conducted geological, geophysical, and geochemical surveys to assess the mineral resources (known) and the mineral resource potential (undiscovered) of the study area. Fieldwork for this report was carried out in 1985 and 1986. No mines, significant prospects, or mining claims are located inside the study area, and no identified resources were found. The wilderness study area has moderate mineral resource potential for gold, silver, and mercury and for zeolite minerals. A low potential also exists for geothermal energy resources, and potential for oil and gas is unknown.

Yellow Canary uranium deposits, Daggett County, Utah

USGS Publications Warehouse

Wilmarth, Verl Richard

1953-01-01

The Yellow Canary uranium deposit is on the west side of Red Creek Canyon in the northern part of the Uinta Mountains, Daggett County, Utah. Two claims have been developed by means of an adit, three opencuts, and several hundred feet of bulldozer trenches. No uranium ore has been produced from this deposit. The deposit is in the pre-Cambrian Red Creek quartzite. This formation is composed of intercalated beds of quartzite, hornblendite, garnet schist, staurolite schist, and quartz-mica schist and is intruded by dioritic dikes. A thick unit of highly fractured white quartzite near the top of the formation contains tyuyamunite as coatings on fracture surfaces. The tyuyamunite is associated with carnotite, volborthite, iron oxides, azurite, malachite, brochantite, and hyalite. The uranium and vanadium minerals are probably alteration products of primary minerals. The uranium content of 15 samples from this property ranged from 0.000 to 0.57 percent.

Indian Creek uranium prospects, Beaver County, Utah

USGS Publications Warehouse

Wyant, Donald G.; Stugard, Frederick

1951-01-01

The secondary uranium minerals metatorbernite (?) and autunite (?) were discovered at Indian Creek in the spring of 1950. The deposits, in sec. 26, T. 27 S., R. 6 T., Beaver County, Utah, are 20 miles west of Marysvale, and about three-eighths of a mile east of a quartz monzonite stock. The uranium minerals are sparsely disseminated in argillized and silicified earlier Tertiary Bullion Canyon latite and related volcanic rock beneart, but close to, the contact of the overlying later Tertiary Mount Belknap gray rhyolite. The prospects are in a landslide area where exposures are scarce. Therefore, trend and possible continuity of the altered and the uraniferous zones cannot be established definitely. The occurrence of secondary uranium minerals in beidellite-montmorillonite rock, formed by alteration of earlier Tertiary rocks near a quartz monzonite stock, is similar to that in some of the deposits in the Marysvale uranium district.

Preliminary geologic map of Black Canyon and surrounding region, Nevada and Arizona

USGS Publications Warehouse

Felger, Tracey J.; Beard, L. Sue; Anderson, Zachary W.; Fleck, Robert J.; Wooden, Joseph L.; Seixas, Gustav B.

2014-01-01

Thermal springs in Black Canyon of the Colorado River, downstream of Hoover Dam, are important recreational, ecological, and scenic features of the Lake Mead National Recreation Area. This report presents the results from a U.S. Geological Survey study of the geologic framework of the springs. The study was conducted in cooperation with the National Park Service and funded by both the National Park Service and National Cooperative Geologic Mapping Program of the U.S. Geological Survey. The report has two parts: A, a 1:48,000-scale geologic map created from existing geologic maps and augmented by new geologic mapping and geochronology; and B, an interpretive report that presents results based on a collection of fault kinematic data near springs within Black Canyon and construction of 1:100,000-scale geologic cross sections that extend across the western Lake Mead region. Exposures in Black Canyon are mostly of Miocene volcanic rocks, underlain by crystalline basement composed of Miocene plutonic rocks or Proterozoic metamorphic rocks. The rocks are variably tilted and highly faulted. Faults strike northwest to northeast and include normal and strike-slip faults. Spring discharge occurs along faults intruded by dacite dikes and plugs; weeping walls and seeps extend away from the faults in highly fractured rock or relatively porous volcanic breccias, or both. Results of kinematic analysis of fault data collected along tributaries to the Colorado River indicate two episodes of deformation, consistent with earlier studies. The earlier episode formed during east-northeast-directed extension, and the later during east-southeast-directed extension. At the northern end of the study area, pre-existing fault blocks that formed during the first episode were rotated counterclockwise along the left-lateral Lake Mead Fault System. The resulting fault pattern forms a complex arrangement that provides both barriers and pathways for groundwater movement within and around Black

CHAMA RIVER CANYON WILDERNESS AND CONTIGUOUS ROADLESS AREA, NEW MEXICO.

USGS Publications Warehouse

Ridgley, Jennie L.; Light, Thomas D.

1984-01-01

Results of mineral surveys indicate that the Chama River Canyon Wilderness and contiguous roadless area in new Mexico have a probable mineral-resource potential for copper with associated uranium and silver. Gypsum occurs throughout the area, exposed in the canyon walls. Further study of the wilderness should concentrate on exploratory drilling to test the oil and gas potential of Pennsylvanian strata and evaluate vanadium anomalies in the Todilto as a prospecting guide for locating uranium.

Detail of Bright Angel stone vault, containing condenser, Hoffman condensation ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail of Bright Angel stone vault, containing condenser, Hoffman condensation pump, Jennings vacuum heating pump, and misc. pipes and valves. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

Captured in Stone: Women in the Rock Art of Canyon de Chelly.

ERIC Educational Resources Information Center

Travis, Tara

1997-01-01

Describes the pictographs (painted images on stone) and petroglyphs (pecked images on stone) found in the Canyon de Chelly National Monument in Arizona. Canyon de Chelly includes one of the largest concentrations of American Indian rock art in the southwest. Discusses the depiction of women in these images. (MJP)

Trees as environmental modifier to improve street canyon for pedestrian activities in Muscat

NASA Astrophysics Data System (ADS)

Khudhayer, Wael A.; Shaaban, Awni K.; Sukor, Nur Sabahiah Abdul

2017-10-01

Street shading efficiency is a function of orientation and profile proportion of its height to width. Under high sun altitude conditions, minimization of solar irradiance within the urban environment may often be a significant criterion in urban design. This reduction in solar irradiance achieved when the obstruction angle is large (high H/W ratio, H=height, W=width). High H/W values often lessen the solar access to streets. The horizontal sprawl of Muscat region is an example of low H/W ratio represented the remarkable challenge that causes the lack of shading rates in the urban street. This characteristic proliferates the negative impact on the pedestrian activities in the urban street. This research aims to improve the morphology of the street to promote the pedestrian behavior. The amendment based on suggesting different configurations of trees to increase effective shading of the urban street in Muscat. The street canyon abstracted into a virtual elongated channel formed of floor and walls of equal heights on both sides. Four street orientations (E/W, N/S, NE/SW, NW/SE) and three H/W ratio (0.5,1 and 2) are considered sufficient representative of street typologies. A mathematical model developed for calculation of shading efficiency of each street canyon. The trees assumed in this study as canyon's modifier to adjust the low H/W ratio of a street canyon to a higher one. Local trees and other plants in Muscat were studied concerning their morphology. The analysis selected two case study in Muscat to investigate the shading performance of their street canyons subsequently propose the modifications to improve it. The research concluded that the suggested changes of the street canyon by using a particular type of trees could increase the H/W ratio of street canyon significantly.

Feral Cattle in the White Rock Canyon Reserve at Los Alamos National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hathcock, Charles D.; Hansen, Leslie A.

2014-03-27

At the request of the Los Alamos Field Office (the Field Office), Los Alamos National Security (LANS) biologists placed remote-triggered wildlife cameras in and around the mouth of Ancho Canyon in the White Rock Canyon Reserve (the Reserve) to monitor use by feral cattle. The cameras were placed in October 2012 and retrieved in January 2013. Two cameras were placed upstream in Ancho Canyon away from the Rio Grande along the perennial flows from Ancho Springs, two cameras were placed at the north side of the mouth to Ancho Canyon along the Rio Grande, and two cameras were placed atmore » the south side of the mouth to Ancho Canyon along the Rio Grande. The cameras recorded three different individual feral cows using this area as well as a variety of local native wildlife. This report details our results and issues associated with feral cattle in the Reserve. Feral cattle pose significant risks to human safety, impact cultural and biological resources, and affect the environmental integrity of the Reserve. Regional stakeholders have communicated to the Field Office that they support feral cattle removal.« less

Wind tunnel simulation of air pollution dispersion in a street canyon.

PubMed

Civis, Svatopluk; Strizík, Michal; Janour, Zbynek; Holpuch, Jan; Zelinger, Zdenek

2002-01-01

Physical simulation was used to study pollution dispersion in a street canyon. The street canyon model was designed to study the effect of measuring flow and concentration fields. A method of C02-laser photoacoustic spectrometry was applied for detection of trace concentration of gas pollution. The advantage of this method is its high sensitivity and broad dynamic range, permitting monitoring of concentrations from trace to saturation values. Application of this method enabled us to propose a simple model based on line permeation pollutant source, developed on the principle of concentration standards, to ensure high precision and homogeneity of the concentration flow. Spatial measurement of the concentration distribution inside the street canyon was performed on the model with reference velocity of 1.5 m/s.

Origin of the Colorado River experimental flood in Grand Canyon

USGS Publications Warehouse

Andrews, E.D.; Pizzi, L.A.

2000-01-01

The Colorado River is one of the most highly regulated and extensively utilized rivers in the world. Total reservoir storage is approximately four times the mean annual runoff of ~17 x 109 m3 year -1. Reservoir storage and regulation have decreased annual peak discharges and hydroelectric power generation has increased daily flow variability. In recent years, the incidental impacts of this development have become apparent especially along the Colorado River through Grand Canyon National Park downstream from Glen Canyon Dam and caused widespread concern. Since the completion of Glen Canyon Dam, the number and size of sand bars, which are used by recreational river runners and form the habitat for native fishes, have decreased substantially. Following an extensive hydrological and geomorphic investigation, an experimental flood release from the Glen Canyon Dam was proposed to determine whether sand bars would be rebuilt by a relatively brief period of flow substantially greater than the normal operating regime. This proposed release, however, was constrained by the Law of the River, the body of law developed over 70 years to control and distribute Colorado River water, the needs of hydropower users and those dependent upon hydropower revenues, and the physical constraints of the dam itself. A compromise was reached following often difficult negotiations and an experimental flood to rebuild sand bars was released in 1996. This flood, and the process by which it came about, gives hope to resolving the difficult and pervasive problem of allocation of water resources among competing interests.The Colorado River is one of the most highly regulated and extensively utilized rivers in the world. Total reservoir storage is approximately four times the mean annual runoff of approximately 17??109 m3 year-1. Reservoir storage and regulation have decreased annual peak discharges and hydroelectric power generation has increased daily flow variability. In recent years, the

The marine soundscape of the Perth Canyon

NASA Astrophysics Data System (ADS)

Erbe, Christine; Verma, Arti; McCauley, Robert; Gavrilov, Alexander; Parnum, Iain

2015-09-01

The Perth Canyon is a submarine canyon off Rottnest Island in Western Australia. It is rich in biodiversity in general, and important as a feeding and resting ground for great whales on migration. Australia's Integrated Marine Observing System (IMOS) has moorings in the Perth Canyon monitoring its acoustical, physical and biological oceanography. Data from these moorings, as well as weather data from a near-by Bureau of Meteorology weather station on Rottnest Island and ship traffic data from the Australian Maritime Safety Authority were correlated to characterise and quantify the marine soundscape between 5 and 3000 Hz, consisting of its geophony, biophony and anthrophony. Overall, biological sources are a strong contributor to the soundscape at the IMOS site, with whales dominating seasonally at low (15-100 Hz) and mid frequencies (200-400 Hz), and fish or invertebrate choruses dominating at high frequencies (1800-2500 Hz) at night time throughout the year. Ships contribute significantly to the 8-100 Hz band at all times of the day, all year round, albeit for a few hours at a time only. Wind-dependent noise is significant at 200-3000 Hz; winter rains are audible underwater at 2000-3000 Hz. We discuss how passive acoustic data can be used as a proxy for ocean weather. Passive acoustics is an efficient way of monitoring animal visitation times and relative densities, and potential anthropogenic influences.

77 FR 59607 - Black Canyon Hydro, LLC; Notice of Environmental Site Review

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-28

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 14110-001] Black Canyon Hydro, LLC; Notice of Environmental Site Review On Wednesday, October 3, 2012, at 3 p.m., Commission staff will be participating in an environmental site review for the proposed Black Canyon Hydroelectric Project. All interested participants should mee...

Anthropogenic impacts on deep submarine canyons of the western Mediterranean Sea

NASA Astrophysics Data System (ADS)

Sanchez-Vidal, A.; Tubau, X.; Llorca, M.; Woodall, L.; Canals, M.; Farré, M.; Barceló, D.; Thompson, R.

2016-02-01

Submarine canyons are seafloor geomorphic features connecting the shallow coastal ocean to the deep continental margin and basin. Often considered biodiversity hotspots, submarine canyons have been identified as preferential pathways for water, sediment, pollutant and litter transfers from the coastal to the deep ocean. Here we provide insights on the presence of some of the most insidious man-made debris and substances in submarine canyons of the western Mediterranean Sea, which are relevant to achieve a "Good Environmental Status" by 2020 as outlined in the European Union's ambitious Marine Strategy Framework Directive. Ranked by size on a decreasing basis, we review the origin, distribution and transport mechanisms of i) marine litter, including plastic, lost fishing gear and metallic objects; ii) microplastics in the form of fibers of rayon, polyester, polyamide and acetates; and iii) persistent organic pollutants including the toxic and persistent perfluoroalkyl substances. This integrated analysis allows us to understand the pivotal role of atmospheric driven oceanographic processes occurring in Mediterranean deep canyons (dense shelf water cascading, coastal storms) in spreading any type of man-made compound to the deep sea, where they sink and accumulate before getting buried.

Geologic map of the Vigo NE quadrangle, Lincoln County, Nevada

USGS Publications Warehouse

Scott, Robert B.; Harding, Anne E.

2006-01-01

This map of the Vigo NE quadrangle, Lincoln County, Nevada records the distribution, stratigraphy, and structural relationships of Tertiary intracaldera lavas and tuffs in the southeastern part of the Kane Springs Wash caldera, extracaldera Tertiary and upper Paleozoic rocks, and late Cenozoic surficial deposits both within and outside the caldera. The alkaline to peralkaline Kane Springs Wash caldera is the youngest (14 Ma) of three chemically related metaluminous to peralkaline calderas (Boulder Canyon caldera, 15 Ma; Narrow Canyon caldera, 16 Ma) of the nested Kane Springs Wash caldera complex. The chemistry of this caldera complex became progressively more alkalic with time, in contrast to the older calc-alkalic calderas and caldera complexes to the north that migrated progressively southward in eastern Nevada. The increasingly peralkaline eruptions from the Kane Springs Wash caldera complex reached a climax that was simultaneous with the end of both rapid extension and magmatism in this part of the Basin and Range. Using the assumption that degree of tilting is related to the degree of extension, the rate of extension increased until the abrupt halt at about 14 Ma. Silicic volcanism terminated at the Kane Springs Wash caldera followed only by local sporadic basaltic eruptions that ended by about 8 Ma. The northern boundary of an east-west-trending amagmatic corridor appears in the Vigo NE quadrangle south of the Kane Springs Wash caldera.

Side-scan sonar imaging of the Colorado River, Grand Canyon

USGS Publications Warehouse

Anima, Roberto; Wong, Florence L.; Hogg, David; Galanis, Peter

2007-01-01

This paper presents data collection methods and side-scan sonar data collected along the Colorado River in Grand Canyon in August and September of 2000. The purpose of the data collection effort was to image the distribution of sand between Glen Canyon Dam and river mile 87.4 before and after the 31,600 cfs flow of September 6-8. The side-scan sonar imaging focused on pools between rapids but included smaller rapids where possible.

75 FR 51990 - Combined Notice of Filings #1

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-24

...-1225-009; ER09- 1321-005. Applicants: Blue Canyon Windpower II LLC, Cloud County Wind Farm, LLC, Blue Canyon Windpower LLC, Blue Canyon Windpower V LLC. Description: Supplement to Updated Market Power Anaylsis for Blue Canyon Windpower LLC, et. al. Filed Date: 08/17/2010. Accession Number: 20100817-5034...

An In Situ Radiological Survey of Three Canyons at the Los Alamos National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

R.J. Maurer

1999-06-01

An in situ radiological survey of Mortandad, Ten Site, and DP Canyons at the Los Alamos National Laboratory was conducted during August 19-30, 1996. The purpose of this survey was to measure the quantities of radionuclides that remain in the canyons from past laboratory operations. A total of 65 in situ measurements were conducted using high-resolution gamma radiation detectors at 1 meter above the ground. The measurements were obtained in the streambeds of the canyons beginning near the water-release points at the laboratories and extending to the ends of the canyons. Three man-made gamma-emitting radionuclides were detected in the canyons:more » americium-241 ({sup 241}Am), cesium-137 ({sup 137}Cs), and cobalt-60 ({sup 60}Co). Estimated contamination levels ranged from 13.3-290.4 picocuries per gram (pCi/g)for {sup 241}Am, 4.4-327.8 pCi/g for {sup 137}Cs, and 0.4-2.6 pCi/g for {sup 60}Co.« less

Draft environmental assessment: Davis Canyon site, Utah. Nuclear Waste Policy Act (Section 112). [Contains glossary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1984-12-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah, as one of nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for Nuclear Waste Repositories. These evaluations are reported in this draft environmental assessment (EA), which is being issued for public review and comment. The DOE findings and determinations that are based on these evaluationsmore » are preliminary and subject to public review and comment. A final EA will be prepared after considering the comments received. On the basis of the evaluations reported in this draft EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. The site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site - the Lavender Canyon site. Although the Lavender Canyon site appears to be suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. Furthermore, the DOE finds that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is proposing to nominate the Davis Canyon site as one of five sites suitable for characterization. Having compared the Davis Canyon site with the other four sites proposed for nomination, the DOE has determined that the Davis Canyon site is not one of the three preferred sites for recommendation to the President as candidates for characterization.« less

Potential hazards from floodflows in Grapevine Canyon, Death Valley National Monument, California and Nevada

USGS Publications Warehouse

Bowers, J.C.

1990-01-01

Grapevine Canyon is on the western slope of the Grapevine Mountains in the northern part of Death Valley National Monument , California and Nevada. Grapevine Canyon Road covers the entire width of the canyon floor in places and is a frequently traveled route to Scotty 's Castle in the canyon. The region is arid and subject to flash flooding because of infrequent but intense convective storms. When these storms occur, normally in the summer, the resulting floods may create a hazard to visitor safety and property. Historical data on rainfall and floodflow in Grapevine Canyon are sparse. Data from studies made for similar areas in the desert mountains of southern California provide the basis for estimating discharges and the corresponding frequency of floods in the study area. Results of this study indicate that high-velocity flows of water and debris , even at shallow depths, may scour and damage Grapevine Canyon Road. When discharge exceeds 4,900 cu ft/sec, expected at a recurrence interval of between 25 and 50 years, the Scotty 's Castle access road and bridge may be damaged and the parking lot partly inundated. A flood having a 100-year or greater recurrence interval probably would wash out the bridge and present a hazard to the stable and garage buildings but not to the castle buildings, whose foundations are higher than the predicted maximum flood level. (USGS)

Recent sediment transport and deposition in the Cap-Ferret Canyon, South-East margin of Bay of Biscay

NASA Astrophysics Data System (ADS)

Schmidt, Sabine; Howa, Hélène; Diallo, Amy; Martín, Jacobo; Cremer, Michel; Duros, Pauline; Fontanier, Christophe; Deflandre, Bruno; Metzger, Edouard; Mulder, Thierry

2014-06-01

The Cap-Ferret Canyon (CFC), a major morphologic feature of the eastern margin of the Bay of Biscay, occupies a deep structural depression that opens about 60 km southwest of the Gironde Estuary. Detailed depth profiles of the particle-reactive radionuclides 234Th and 210Pb in interface sediments were used to characterise the present sedimentation (bioturbation, sediment mass accumulation, and focusing) in the CFC region. Two bathymetric transects were sampled along the CFC axis and the southern adjacent margin. Particle fluxes were recorded from the nearby Landes Plateau by means of sediment traps in 2006 and 2007. This dataset provides a new and comprehensive view of particulate matter transfer in the Cap-Ferret Canyon region, through a direct comparison of the canyon with the adjacent southern margin. Radionuclide profiles (234Th and 210Pb) and mass fluxes demonstrate that significant particle dynamics occur on the SE Aquitanian margin in comparison with nearby margins. The results also suggest show three distinct areas in terms of sedimentary activity. In the upper canyon (<500 m), there is little net sediment accumulation, suggesting a by-pass area. Sediment focusing is apparent at the middle canyon (500-1500 m), that therefore acts as a depocenter for particles from the shelf and the upper canyon. The lower canyon (>2000 m) can be considered inactive at annual or decadal scales. In contrast with the slow and continuous accumulation of relatively fresh material that characterises the middle canyon, the lower canyon receives pulses of sediment via gravity flows on longer time scales. At decadal scale, the CFC can be considered as a relatively quiescent canyon. The disconnection of the CFC from major sources of sediment delivery seems to limit its efficiency in particle transfer from coastal areas to the adjacent ocean basin.

Fourmile Canyon: Living with wildfire

Treesearch

Hannah Brenkert-Smith; Patricia A. Champ

2011-01-01

The most devastating wildfire in Colorado's history in terms of property loss began on Labor Day, September 6, 2010. The Fourmile Canyon Fire was located just 5 miles west of downtown Boulder, CO, in a wildland-urban interface (WUI) zone with homes located on steep slopes and in dense ponderosa pine and Douglas-fir forest. The fire, fueled by high winds, burned 6,...

Sediment dynamics and post-glacial evolution of the continental shelf around the Blanes submarine canyon head (NW Mediterranean)

NASA Astrophysics Data System (ADS)

Durán, Ruth; Canals, Miquel; Lastras, Galderic; Micallef, Aaron; Amblas, David; Pedrosa-Pàmies, Rut; Sanz, José Luis

2013-11-01

The Blanes submarine canyon (BC) deeply incises the Catalan continental shelf in the NW Mediterranean Sea. As a consequence of the closeness (only 4 km) of its head to the coastline and the mouth of the Tordera River, the canyon has a direct influence on the shelf dispersal system as it collects large amounts of sediment, mainly during high-energy events. Multibeam bathymetry, backscatter imagery and very-high resolution seismic reflection profiles have allowed characterizing the morphology of the continental shelf around the canyon head, also identifying sediment sources and transport pathways into the canyon. The morphological data have also been used to reconstruct the evolution of the continental shelf during the last sea-level transgression so that the current understanding of shelf-to-canyon sediment exchanges through time could be improved. The continental shelf surrounding the BC consists of both depositional and erosional or non-depositional areas. Depositional areas display prominent sediment bodies, a generally smooth bathymetry and variable backscatter. These include: (i) an area of modern coarse-grained sediment accumulation that comprises the inner shelf; (ii) a modern fine-grained sedimentation area on the middle shelf offshore Tossa de Mar; and (iii) a modern sediment depleted area that covers most of the middle and outer shelf to the west of the canyon head. Erosional and non-depositional areas display a rough topography and high backscatter, and occur primarily to the east of the canyon head, where the arrival of river-fed inputs is very small. In agreement with this pattern, the continental shelf north and west of the canyon head likely is the main source of shelf sediment into the canyon. To the north, a pattern of very high backscatter extends from the coastline to the canyon head, suggesting the remobilization and off-shelf export of fines. Additionally, relict near-shore sand bodies developed over the Barcelona shelf that extend to the canyon

Assesment of longwave radiation effects on air quality modelling in street canyons

NASA Astrophysics Data System (ADS)

Soucasse, L.; Buchan, A.; Pain, C.

2016-12-01

Computational Fluid Dynamics is widely used as a predictive tool to evaluate people's exposure to pollutants in urban street canyons. However, in low-wind conditions, flow and pollutant dispersion in the canyons are driven by thermal effects and may be affected by longwave (infrared) radiation due to the absorption and emission of water vapor contained in the air. These effects are mostly ignored in the literature dedicated to air quality modelling at this scale. This study aims at quantifying the uncertainties due to neglecting thermal radiation in air quality models. The Large-Eddy-Simulation of air flow in a single 2D canyon with a heat source on the ground is considered for Rayleigh and Reynolds numbers in the range of [10e8-10e10] and [5.10e3-5.10e4] respectively. The dispersion of a tracer is monitored once the statistically steady regime is reached. Incoming radiation is computed for a mid-latitude summer atmosphere and canyon surfaces are assumed to be black. Water vapour is the only radiating molecule considered and a global model is used to treat the spectral dependancy of its absorption coefficient. Flow and radiation fields are solved in a coupled way using the finite element solvers Fluidity and Fetch which have the capability of adapting their space and angular resolution according to an estimate of the solution error. Results show significant effects of thermal radiation on flow patterns and tracer dispersion. When radiation is taken into account, the air is heated far from the heat source leading to a stronger natural convection flow. The tracer is then dispersed faster out of the canyon potentially decreasing people's exposure to pollution within the street canyon.

75 FR 11155 - Combined Notice of Filings No. 1

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-10

...; ER08-1225-009; ER09- 1321-005. Applicants: Blue Canyon Windpower II LLC, Cloud County Wind Farm, LLC, Blue Canyon Windpower LLC, Blue Canyon Windpower V LLC. Description: Updated Market Power Analysis of Blue Canyon Windpower LLC, et al. Filed Date: 02/26/2010. Accession Number: 20100226-5194. Comment Date...

78 FR 17389 - Clark Canyon Hydro, LLC; Notice of Application for Amendment of License and Soliciting Comments...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-21

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 12429-009] Clark Canyon...: 12429-009. c. Date Filed: January 28, 2013. d. Applicant: Northwest Power Services on behalf of Clark Canyon Hydro, LLC. e. Name of Project: Clark Canyon Dam Hydroelectric Project. f. Location: The Clark...

The Influence of Roof Material on Diurnal Urban Canyon Breathing

NASA Astrophysics Data System (ADS)

Abuhegazy, Mohamed; Yaghoobian, Neda

2017-11-01

Improvements in building energy use, air quality in urban canyons and in general urban microclimates require understanding the complex interaction between urban morphology, materials, climate, and inflow conditions. Review of the literature indicates that despite a long history of valuable urban microclimate studies, more comprehensive approaches are needed to address energy, and heat and flow transport in urban areas. In this study, a more comprehensive simulation of the diurnally varying street canyon flow and associated heat transport is numerically investigated, using Large-eddy Simulation (LES). We use computational modeling to examine the impact of diurnal variation of the heat fluxes from urban surfaces on the air flow and temperature distribution in street canyons with a focus on the role of roof materials and their temperature footprints. A detailed building energy model with a three-dimensional raster-type geometry provides urban surface heat fluxes as thermal boundary conditions for the LES to determine the key aero-thermodynamic factors that affect urban street ventilation.

Prehistoric deforestation at Chaco Canyon?

PubMed Central

Wills, W. H.; Drake, Brandon L.; Dorshow, Wetherbee B.

2014-01-01

Ancient societies are often used to illustrate the potential problems stemming from unsustainable land-use practices because the past seems rife with examples of sociopolitical “collapse” associated with the exhaustion of finite resources. Just as frequently, and typically in response to such presentations, archaeologists and other specialists caution against seeking simple cause-and effect-relationships in the complex data that comprise the archaeological record. In this study we examine the famous case of Chaco Canyon, New Mexico, during the Bonito Phase (ca. AD 860–1140), which has become a prominent popular illustration of ecological and social catastrophe attributed to deforestation. We conclude that there is no substantive evidence for deforestation at Chaco and no obvious indications that the depopulation of the canyon in the 13th century was caused by any specific cultural practices or natural events. Clearly there was a reason why these farming people eventually moved elsewhere, but the archaeological record has not yet produced compelling empirical evidence for what that reason might have been. Until such evidence appears, the legacy of Ancestral Pueblo society in Chaco should not be used as a cautionary story about socioeconomic failures in the modern world. PMID:25071220

Experimental simulation of air quality in street canyon under changes of building orientation and aspect ratio.

PubMed

Yassin, Mohamed F; Ohba, Masaake

2012-09-01

To assist validation of numerical simulations of urban pollution, air quality in a street canyon was investigated using a wind tunnel as a research tool under neutral atmospheric conditions. We used tracer gas techniques from a line source without buoyancy. Ethylene (C(2)H(4)) was used as the tracer gas. The street canyon model was formed of six parallel building rows of the same length. The flow and dispersion field was analyzed and measured using a hot-wire anemometer with split fiber probe and fast flame ionization detector. The diffusion flow field in the boundary layer within the street canyon was examined at different locations, with varying building orientations (θ=90°, 112.5°, 135° and 157.5°) and street canyon aspect ratios (W/H=1/2, 3/4 and 1) downwind of the leeward side of the street canyon model. Results show that velocity increases with aspect ratio, and with θ>90°. Pollutant concentration increases as aspect ratio decreases. This concentration decreases exponentially in the vertical direction, and decreases as θ increases from 90°. Measured pollutant concentration distributions indicate that variability of building orientation and aspect ratio in the street canyon are important for estimating air quality in the canyon. The data presented here can be used as a comprehensive database for validation of numerical models.

Evaluation of the thermal structure in an urban street canyon: field measurements and model simulation

NASA Astrophysics Data System (ADS)

Giovannini, L.; de Franceschi, M.; Zardi, D.

2009-04-01

The results of a research project, aiming at providing tools and criteria to evaluate the temperature field inside an urban street canyon, are presented. Temperature measurements have been carried out, both in summertime and in wintertime, inside a North-South oriented urban canyon in the city of Trento (Italy) in the Alps, with sensors placed at various heights on the front of buildings flanking the street and on top of traffic lights in the middle of the canyon. The results have been analyzed in comparison with data from an automated weather station placed close to the street canyon, at 33 m above ground level and taken as a reference for the above roof-top level. During sunny days a well defined cycle was identified in the daily evolution of air temperature measured by the sensors inside the urban canyon, which was primarily influenced by direct solar radiation. As expected, during the morning the East-facing sensors warmed up faster than the other ones, while in the afternoon the West-facing instruments were the warmest. In most cases the air temperature inside the canyon was higher than above roof level, with differences depending on weather conditions and hour of the day. The dataset allowed to characterize the microclimate of the urban canopy layer and provided a basis for testing the ability of a simple numerical model to simulate the thermal structure inside the urban canyon. The model displays the following characteristics: assignment of distinct surface types (road, walls and roofs), in order to better simulate their physical properties; computation of radiative exchanges inside the canyon based on view factors between the different surfaces and explicitly treating both the solar reflections and the shadows; storage heat flux simulated by means of the heat conduction equation. The model requires as input the geometry parameters of the street and the values of meteorological variables measured above roof level. The main outputs are the heat fluxes

Exhumation Across Hells Canyon and the Arc-continent Boundary of Idaho-Oregon

NASA Astrophysics Data System (ADS)

Kahn, M.; Fayon, A. K.; Tikoff, B.

2015-12-01

Hells Canyon is located along the Idaho-Oregon border. It is proximal to the Salmon River suture zone, the Cretaceous-age western margin of North America that juxtaposes accreted terranes to the west and cratonic North America to the east. We applied (U-Th)/He zircon and apatite thermochronometry to samples along an EW transect across Hells Canyon. (U-Th)/He zircon and apatite ages record the time at which rocks cool below ~ 200 and 60 °C, respectively, providing information on both the timing and rate at which rocks cooled. Samples were collected with respect to structural position relative to the basal Columbia River basalt flow (Imnaha), dated at ~ 17.4 Ma, with most samples taken <100 m below the contact. Given that all localities were at the Earth's surface - and thus cooled below 60˚C - at ~ 17.4 Ma, the variation in obtained ages are assessed relative to this common datum. The easternmost sites were taken on the western margin of the Idaho batholith at Lava Buttes, ID at ~2,700 m elevation: The (U-Th)/He zircon and apatite ages are 64.9±4.6 Ma and 53.8±4.9 Ma, respectively. The westernmost sites occur in the Wallowa Mountains, Oregon, where the base of the Imnaha flow exists at ~3,000 m: The (U-Th)/He zircon and apatite ages are 136.2±42.8 Ma and 21.7±10.0 Ma. Additionally, the basal basalt contact occurs at ~900 m and ~600 m at the bottom of the Salmon River Canyon and Hells Canyon respectively. The (U-Th)/He zircon and apatite ages are 73.1±14.6 Ma and 20.0±7.4 Ma, respectively, for the Salmon River Canyon and 88.6±2.4 Ma and 3.4±0.6 Ma, respectively, for Hells Canyon. The data indicate that: 1) The western Wallowa (accreted) terrane cooled below ~200 °C prior to the formation of the Idaho batholith; 2) The western side of the Idaho batholith shows a rapid and consistent cooling between ~200 °C and ~60 °C in the Paleogene; and 3) Samples at low elevation in Hells Canyon cooled below 60˚C in the Pliocene, which requires reburial of the rocks

Flow and Pollutant Transport in Urban Street Canyons of Different Aspect Ratios with Ground Heating: Large-Eddy Simulation

NASA Astrophysics Data System (ADS)

Li, Xian-Xiang; Britter, Rex E.; Norford, Leslie K.; Koh, Tieh-Yong; Entekhabi, Dara

2012-02-01

A validated large-eddy simulation model was employed to study the effect of the aspect ratio and ground heating on the flow and pollutant dispersion in urban street canyons. Three ground-heating intensities (neutral, weak and strong) were imposed in street canyons of aspect ratio 1, 2, and 0.5. The detailed patterns of flow, turbulence, temperature and pollutant transport were analyzed and compared. Significant changes of flow and scalar patterns were caused by ground heating in the street canyon of aspect ratio 2 and 0.5, while only the street canyon of aspect ratio 0.5 showed a change in flow regime (from wake interference flow to skimming flow). The street canyon of aspect ratio 1 does not show any significant change in the flow field. Ground heating generated strong mixing of heat and pollutant; the normalized temperature inside street canyons was approximately spatially uniform and somewhat insensitive to the aspect ratio and heating intensity. This study helps elucidate the combined effects of urban geometry and thermal stratification on the urban canyon flow and pollutant dispersion.

Upper Miocene-Pliocene provenance evolution of the Central Canyon in northwestern South China Sea

NASA Astrophysics Data System (ADS)

Cui, Yuchi; Shao, Lei; Qiao, Peijun; Pei, Jianxiang; Zhang, Daojun; Tran, Huyen

2018-06-01

Provenance studies of the Central Canyon, Qiongdongnan Basin has provided significant insights into paleographic and sedimentology research of the South China Sea (SCS). A suite of geochemical approaches mainly including rare earth elemental (REE) analysis and detrital zircon U-Pb dating has been systematically applied to the "source-to-sink" system involving our upper Miocene-Pliocene Central Canyon sediments and surrounding potential source areas. Based on samples tracing the entire course of the Central Canyon, REE distribution patterns indicate that the western channel was generally characterized by positive Eu anomalies in larger proportion, in contrast to the dominance of negative values of its eastern side during late Miocene-Pliocene. Additionally, for the whole canyon and farther regions of Qiongdongnan Basin, the number of samples bearing negative Eu anomalies tended to increase within younger geological strata. On the other hand, U-Pb geochronology results suggest a wide Proterozoic to Mesozoic age range with peak complexity in Yanshanian, Indosinian, Caledonian and Jinningian periods. However in detail, age combination of most western samples displayed older-age signatures than the eastern. To make it more evidently, western boreholes of the Central Canyon are mainly characterized with confined Indosinian and Caledonian clusters which show great comparability with mafic-to-ultramafic source of Kontum Massif of Central Vietnam, while eastern samples largely bear with distinguishable Yanshanian and Indosinian peaks which more resemble with Hainan Island. Based on geochemistry and geochronology analyses, two significant suppliers and sedimentary infilling processes are generated: (1) the Indosinian collision orogenic belt in central-northern Vietnam, Indochina has ever played significant role in Central Canyon sedimentary evolution, (2) Hainan Island once as a typical provenance restricted within eastern Central Canyon, has been enlarging its influence

Physical linkages between an offshore canyon and surf zone morphologic change

NASA Astrophysics Data System (ADS)

Hansen, Jeff E.; Raubenheimer, Britt; Elgar, Steve; List, Jeffrey H.; Lippmann, Thomas C.

2017-04-01

The causes of surf zone morphologic changes observed along a sandy beach onshore of a submarine canyon were investigated using field observations and a numerical model (Delft3D/SWAN). Numerically simulated morphologic changes using four different sediment transport formulae reproduce the temporal and spatial patterns of net cross-shore integrated (between 0 and 6.5 m water depths) accretion and erosion observed in a ˜300 m alongshore region, a few hundred meters from the canyon head. The observations and simulations indicate that the accretion or erosion results from converging or diverging alongshore currents driven primarily by breaking waves and alongshore pressure gradients. The location of convergence or divergence depends on the direction of the offshore waves that refract over the canyon, suggesting that bathymetric features on the inner shelf can have first-order effects on short-term nearshore morphologic change.

Walnut Canyon National Monument : Acoustical Monitoring 2010

DOT National Transportation Integrated Search

2013-06-01

During the summer of 2010 (July - August), the Volpe Center collected baseline acoustical data at Walnut Canyon National Monument (WACA) at a site deployed for approximately 30 days. The baseline data collected during this period will help park manag...

Marine litter in submarine canyons of the Bay of Biscay

NASA Astrophysics Data System (ADS)

van den Beld, Inge M. J.; Guillaumont, Brigitte; Menot, Lénaïck; Bayle, Christophe; Arnaud-Haond, Sophie; Bourillet, Jean-François

2017-11-01

Marine litter is a matter of increasing concern worldwide, from shallow seas to the open ocean and from beaches to the deep-seafloor. Indeed, the deep sea may be the ultimate repository of a large proportion of litter in the ocean. We used footage acquired with a Remotely Operated Vehicle (ROV) and a towed camera to investigate the distribution and composition of litter in the submarine canyons of the Bay of Biscay. This bay contains many submarine canyons housing Vulnerable Marine Ecosystems (VMEs) such as scleractinian coral habitats. VMEs are considered to be important for fish and they increase the local biodiversity. The objectives of the study were to investigate and discuss: (i) litter density, (ii) the principal sources of litter, (iii) the influence of environmental factors on the distribution of litter, and (iv) the impact of litter on benthic communities. Litter was found in all 15 canyons and at three sites on the edge of the continental shelf/canyon, in 25 of 29 dives. The Belle-île and Arcachon Canyons contained the largest amounts of litter, up to 12.6 and 9.5 items per 100 images respectively. Plastic items were the most abundant (42%), followed by fishing-related items (16%). The litter had both a maritime and a terrestrial origin. The main sources could be linked to fishing activities, major shipping lanes and river discharges. Litter appeared to accumulate at water depths of 801-1100 m and 1401-1700 m. In the deeper of these two depth ranges, litter accumulated on a geologically structured area, accounting for its high frequency at this depth. A larger number of images taken in areas of coral in the shallower of these two depth ranges may account for the high frequency of litter detection at this depth. A larger number of litter items, including plastic objects in particular, were observed on geological structures and in coral areas than on areas of bare substratum. The distribution of fishing-related items was similar for the various types of

Simulated Flyover of Mars Canyon Map Animation

NASA Image and Video Library

2014-12-12

This frame from an animation simulates a flyover of a portion of a Martian canyon detailed in a geological map produced by the U.S. Geological Survey and based on observations by the HiRISE camera on NASA Mars Reconnaissance Orbiter.

The down canyon evolution of submarine sediment density flows

NASA Astrophysics Data System (ADS)

Parsons, D. R.; Barry, J.; Clare, M. A.; Cartigny, M.; Chaffey, M. R.; Gales, J. A.; Gwiazda, R.; Maier, K. L.; McGann, M.; Paull, C. K.; O'Reilly, T. C.; Rosenberger, K. J.; Simmons, S.; Sumner, E. J.; Talling, P.; Xu, J.

2017-12-01

Submarine density flows, known as turbidity currents, transfer globally significant volumes of terrestrial and shelf sediments, organic carbon, nutrients and fresher-water into the deep ocean. Understanding such flows has wide implications for global organic carbon cycling, the functioning of deep-sea ecosystems, seabed infrastructure hazard assessments, and interpreting geological archives of Earth history. Only river systems transport comparable volumes of sediment over such large areas of the globe. Despite their clear importance, there are remarkably few direct measurements of these oceanic turbidity currents in action. Here we present results from the multi-institution Coordinated Canyon Experiment (CCE) which deployed multiple moorings along the axis of Monterey Canyon (offshore California). An array of six moorings, with downward looking acoustic Doppler current profilers (ADCP) were positioned along the canyon axis from 290 m to 1850 m water depth. The ADCPs reveal the internal flow structure of submarine density flows at each site. We use a novel inversion method to reconstruct the suspended sediment concentration and flow stratification field during each event. Together the six moorings provide the first ever views of the internal structural evolution of turbidity current events as they evolve down system. Across the total 18-month period of deployment at least 15 submarine sediment density flows were measured with velocities up to 8.1 m/sec, with three of these flows extending 50 kms down the canyon beyond the 1850 m water depth mooring. We use these novel data to highlight the controls on ignition, interval structure and collapse of individual events and discuss the implications for the functioning and deposits produced by these enigmatic flows.

Recent vegetation changes along the Colorado River between Glen Canyon Dam and Lake Mead, Arizona

USGS Publications Warehouse

Turner, Raymond Marriner; Karpiscak, Martin M.

1980-01-01

Vegetation changes in the canyon of the Colorado River between Glen Canyon Dam and Lake Mead were studied by comparing photographs taken prior to completion of Glen Canyon Dam in 1963 with photographs taken afterwards at the same sites. In general, the older pictures show an absence of riparian plants along the banks of the river. The newer photographs of each pair were taken in 1972 through 1976 and reveal an increased density of many plant species. Exotic species, such as saltcedar and camel-thorn, and native riparian plants such as sandbar willow, arrowweed, desert broom and cattail, now form a new riparian community along much of the channel of the Colorado River between Glen Canyon Dam and Lake Mead. The matched photographs also reveal that changes have occurred in the amount of sand and silt deposited along the banks. Detailed maps are presented showing distribution of 25 plant species along the reach of the Colorado River studied. Data showing changes in the hydrologic regime since completion of Glen Canyon Dam are presented. (Kosco-USGS)

A simplified water temperature model for the Colorado River below Glen Canyon Dam

USGS Publications Warehouse

Wright, S.A.; Anderson, C.R.; Voichick, N.

2009-01-01

Glen Canyon Dam, located on the Colorado River in northern Arizona, has affected the physical, biological and cultural resources of the river downstream in Grand Canyon. One of the impacts to the downstream physical environment that has important implications for the aquatic ecosystem is the transformation of the thermal regime from highly variable seasonally to relatively constant year-round, owing to hypolimnetic releases from the upstream reservoir, Lake Powell. Because of the perceived impacts on the downstream aquatic ecosystem and native fish communities, the Glen Canyon Dam Adaptive Management Program has considered modifications to flow releases and release temperatures designed to increase downstream temperatures. Here, we present a new model of monthly average water temperatures below Glen Canyon Dam designed for first-order, relatively simple evaluation of various alternative dam operations. The model is based on a simplified heat-exchange equation, and model parameters are estimated empirically. The model predicts monthly average temperatures at locations up to 421 km downstream from the dam with average absolute errors less than 0.58C for the dataset considered. The modelling approach used here may also prove useful for other systems, particularly below large dams where release temperatures are substantially out of equilibrium with meteorological conditions. We also present some examples of how the model can be used to evaluate scenarios for the operation of Glen Canyon Dam.

Influence of roadside hedgerows on air quality in urban street canyons

NASA Astrophysics Data System (ADS)

Gromke, Christof; Jamarkattel, Nabaraj; Ruck, Bodo

2016-08-01

Understanding pollutant dispersion in the urban environment is an important aspect of providing solutions to reduce personal exposure to vehicle emissions. To this end, the dispersion of gaseous traffic pollutants in urban street canyons with roadside hedges was investigated. The study was performed in an atmospheric boundary layer wind tunnel using a reduced-scale (M = 1:150) canyon model with a street-width-to-building-height ratio of W/H = 2 and a street-length-to-building-height ratio of L/H = 10. Various hedge configurations of differing height, permeability and longitudinal segmentation (continuous over street length L or discontinuous with clearings) were investigated. Two arrangements were examined: (i) two eccentric hedgerows sidewise of the main traffic lanes and (ii) one central hedgerow between the main traffic lanes. In addition, selected configurations of low boundary walls, i.e. solid barriers, were examined. For a perpendicular approach wind and in the presence of continuous hedgerows, improvements in air quality in the center area of the street canyon were found in comparison to the hedge-free reference scenario. The pollutant reductions were greater for the central hedge arrangements than for the sidewise arrangements. Area-averaged reductions between 46 and 61% were observed at pedestrian head height level on the leeward side in front of the building for the centrally arranged hedges and between 18 and 39% for the two hedges arranged sidewise. Corresponding area-averaged reductions ranging from 39 to 55% and from 1 to 20% were found at the bottom of the building facades on the leeward side. Improvements were also found in the areas at the lateral canyon ends next to the crossings for the central hedge arrangements. For the sidewise arrangements, increases in traffic pollutants were generally observed. However, since the concentrations in the end areas were considerably lower compared to those in the center area, an overall improvement remained

An Investigation of Amphitheater-Headed Canyon Distribution, Morphology Variation, and Longitudinal Profile Controls in Escalante and Tarantula Mesa, Utah.

NASA Astrophysics Data System (ADS)

Ryan, A. J.; Whipple, K. X.

2014-12-01

Amphitheater-headed canyons are primarily distinguished from typical fluvial channels by their abrupt headwall terminations. A key goal in the study of river canyons is to establish a reliable link between form and formation processes. This is of particular significance for Mars, where, if such links can be established, amphitheater-headed canyons could be used to determine ancient erosion mechanisms and, by inference, climate conditions. Type examples in arid regions on Earth, such as in Escalante River, Utah, previously have been interpreted as products of groundwater seepage erosion. We investigate amphitheater-headed canyons in Escalante and Tarantula Mesa where variations in canyon head morphology may hold clues for the relative roles of rock properties and fluvial and groundwater processes. In lower Escalante, amphitheaters are only present where canyons have breached the Navajo Sandstone - Kayenta Formation contact. In some canyons, amphitheater development appears to have been inhibited by an abundance of coarse bedload. In Tarantula Mesa, canyons have a variety of headwalls, from amphitheaters to stepped knickzones. Headwall morphology distribution is directly related to the spatially variable presence of knickpoint-forming, fine-grained interbeds within cliff-forming sandstones. Amphitheaters only form where the sandstone unit is undisrupted by these interbeds. Finally, most canyons in Escalante and Tarantula Mesa, regardless of substrate lithology, amphitheater presence, or groundwater spring intensity, are well described by a slope-area power law relationship with regionally constant concavity and normalized steepness indices. This suggests that all channels here are subject to the same erosion rates, independent of groundwater weathering intensity. Thus: 1) variations in canyon headwall form do not necessary relate to differences in fluvial history, 2) stratigraphic variations are clearly of importance in sedimentary canyon systems, and 3) although

Internal wave scattering in continental slope canyons, part 1: Theory and development of a ray tracing algorithm

NASA Astrophysics Data System (ADS)

Nazarian, Robert H.; Legg, Sonya

2017-10-01

When internal waves interact with topography, such as continental slopes, they can transfer wave energy to local dissipation and diapycnal mixing. Submarine canyons comprise approximately ten percent of global continental slopes, and can enhance the local dissipation of internal wave energy, yet parameterizations of canyon mixing processes are currently missing from large-scale ocean models. As a first step in the development of such parameterizations, we conduct a parameter space study of M2 tidal-frequency, low-mode internal waves interacting with idealized V-shaped canyon topographies. Specifically, we examine the effects of varying the canyon mouth width, shape and slope of the thalweg (line of lowest elevation). This effort is divided into two parts. In the first part, presented here, we extend the theory of 3-dimensional internal wave reflection to a rotated coordinate system aligned with our idealized V-shaped canyons. Based on the updated linear internal wave reflection solution that we derive, we construct a ray tracing algorithm which traces a large number of rays (the discrete analog of a continuous wave) into the canyon region where they can scatter off topography. Although a ray tracing approach has been employed in other studies, we have, for the first time, used ray tracing to calculate changes in wavenumber and ray density which, in turn, can be used to calculate the Froude number (a measure of the likelihood of instability). We show that for canyons of intermediate aspect ratio, large spatial envelopes of instability can form in the presence of supercritical sidewalls. Additionally, the canyon height and length can modulate the Froude number. The second part of this study, a diagnosis of internal wave scattering in continental slope canyons using both numerical simulations and this ray tracing algorithm, as well as a test of robustness of the ray tracing, is presented in the companion article.

Nutrient Enrichment Effects on Benthic Biodiversity by the Mississippi River and Submarine Canyon of the Northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Wei, C.; Rowe, G. T.

2008-12-01

Biodiversity is measured by (1) α diversity: number of species in relation to a standardized number of individual within a define habitat; (2) β diversity: compositional change or turnover of species between two or more spatial units; and (3) γ diversity: total number of species in a large geographic area. The pattern of biodiversity is usually driven by various physico-chemical conditions. In the deep sea, a cross-isobath parabolic diversity pattern has been well-documented for benthic macrofauna and the cause has been attributed to a dynamic equilibrium between population growth and competition exclusion along a gradient of declining food resources with depth (Rex 1981). Both nutrient-enriched (dominated by opportunistic species) and oligotrophic conditions (slow growth rate) could depress diversity, while the highest diversity can be reached by competitive equilibrium within communities at intermediate resource conditions. In the Gulf of Mexico (GoM), the discharge of Mississippi River can enhance the organic flux to the seafloor adjacent to the mouth of Mississippi River and Mississippi Canyon. The goal of this study was to test Rex's (1981) dynamic equilibrium model between depth-transects that were exposed to different levels of organic enrichment. Four treatments contrasted along the upper slope (250m to 1500m) included (1) Mississippi Canyon (active canyon), (2) De Soto Canyon (inactive canyon), (3) central slope transect (in proximity to Mississippi Canyon), and (4) the west and east slope transects (away from the influence of the Mississippi River). SeaWifs satellite data confirmed that the head of Mississippi Canyon experience highest surface primary production and export POC flux. The lowest α diversity of benthic macrofauna (collecting between 2000 and 2002) was observed at the head of the Mississippi Canyon where γ diversity was relatively high. This suggested that the canyon head was dominated by opportunistic species due the high POC flux but

Structure-Forming Corals and Sponges and Their Use as Fish Habitat in Bering Sea Submarine Canyons

PubMed Central

Miller, Robert J.; Hocevar, John; Stone, Robert P.; Fedorov, Dmitry V.

2012-01-01

Continental margins are dynamic, heterogeneous settings that can include canyons, seamounts, and banks. Two of the largest canyons in the world, Zhemchug and Pribilof, cut into the edge of the continental shelf in the southeastern Bering Sea. Here currents and upwelling interact to produce a highly productive area, termed the Green Belt, that supports an abundance of fishes and squids as well as birds and marine mammals. We show that in some areas the floor of these canyons harbors high densities of gorgonian and pennatulacean corals and sponges, likely due to enhanced surface productivity, benthic currents and seafloor topography. Rockfishes, including the commercially important Pacific ocean perch, Sebastes alutus, were associated with corals and sponges as well as with isolated boulders. Sculpins, poachers and pleuronectid flounders were also associated with corals in Pribilof Canyon, where corals were most abundant. Fishes likely use corals and sponges as sources of vertical relief, which may harbor prey as well as provide shelter from predators. Boulders may be equivalent habitat in this regard, but are sparse in the canyons, strongly suggesting that biogenic structure is important fish habitat. Evidence of disturbance to the benthos from fishing activities was observed in these remote canyons. Bottom trawling and other benthic fishing gear has been shown to damage corals and sponges that may be very slow to recover from such disturbance. Regulation of these destructive practices is key to conservation of benthic habitats in these canyons and the ecosystem services they provide. PMID:22470486

Effects of street canyon design on pedestrian thermal comfort in the hot-humid area of China.

PubMed

Zhang, Yufeng; Du, Xiaohan; Shi, Yurong

2017-08-01

The design characteristics of street canyons were investigated in Guangzhou in the hot-humid area of China, and the effects of the design factors and their interactions on pedestrian thermal comfort were studied by numerical simulations. The ENVI-met V4.0 (BASIC) model was validated by field observations and used to simulate the micrometeorological conditions and the standard effective temperature (SET) at pedestrian level of the street canyons for a typical summer day of Guangzhou. The results show that the micrometeorological parameters of mean radiant temperature (MRT) and wind speed play key roles in pedestrian thermal comfort. Street orientation has the largest contribution on SET at pedestrian level, followed by aspect ratio and greenery, while surface albedo and interactions between factors have small contributions. The street canyons oriented southeast-northwest or with a higher aspect ratio provide more shade, higher wind speed, and better thermal comfort conditions for pedestrians. Compared with the east-west-oriented street canyons, the north-south-oriented street canyons have higher MRTs and worse pedestrian thermal comfort due to their wider building spacing along the street. The effects of greenery change with the road width and the time of the day. Street canyon design is recommended to improve pedestrian thermal comfort. This study provides a better understanding of the effects of street canyon design on pedestrian thermal comfort and is a useful guide on urban design for the hot-humid area of China.

Structure-forming corals and sponges and their use as fish habitat in Bering Sea submarine canyons.

PubMed

Miller, Robert J; Hocevar, John; Stone, Robert P; Fedorov, Dmitry V

2012-01-01

Continental margins are dynamic, heterogeneous settings that can include canyons, seamounts, and banks. Two of the largest canyons in the world, Zhemchug and Pribilof, cut into the edge of the continental shelf in the southeastern Bering Sea. Here currents and upwelling interact to produce a highly productive area, termed the Green Belt, that supports an abundance of fishes and squids as well as birds and marine mammals. We show that in some areas the floor of these canyons harbors high densities of gorgonian and pennatulacean corals and sponges, likely due to enhanced surface productivity, benthic currents and seafloor topography. Rockfishes, including the commercially important Pacific ocean perch, Sebastes alutus, were associated with corals and sponges as well as with isolated boulders. Sculpins, poachers and pleuronectid flounders were also associated with corals in Pribilof Canyon, where corals were most abundant. Fishes likely use corals and sponges as sources of vertical relief, which may harbor prey as well as provide shelter from predators. Boulders may be equivalent habitat in this regard, but are sparse in the canyons, strongly suggesting that biogenic structure is important fish habitat. Evidence of disturbance to the benthos from fishing activities was observed in these remote canyons. Bottom trawling and other benthic fishing gear has been shown to damage corals and sponges that may be very slow to recover from such disturbance. Regulation of these destructive practices is key to conservation of benthic habitats in these canyons and the ecosystem services they provide.

76 FR 56430 - Boulder Canyon Project

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-13

... Secretary of Energy approves the Fiscal Year (FY) 2012 Base Charge and Rates (Rates) for Boulder Canyon... calculate the Rates and held a question and answer session. 3. At the public information forum held on April... for FY 2012 in greater detail and held a question and answer session. 4. A public comment forum held...

The Glen Canyon Dam adaptive management program: progress and immediate challenges

USGS Publications Warehouse

Hamill, John F.; Melis, Theodore S.; Boon, Philip J.; Raven, Paul J.

2012-01-01

Adaptive management emerged as an important resource management strategy for major river systems in the United States (US) in the early 1990s. The Glen Canyon Dam Adaptive Management Program (‘the Program’) was formally established in 1997 to fulfill a statutory requirement in the 1992 Grand Canyon Protection Act (GCPA). The GCPA aimed to improve natural resource conditions in the Colorado River corridor in the Glen Canyon National Recreation Area and Grand Canyon National Park, Arizona that were affected by the Glen Canyon dam. The Program achieves this by using science and a variety of stakeholder perspectives to inform decisions about dam operations. Since the Program started the ecosystem is now much better understood and several biological and physical improvements have been achieved. These improvements include: (i) an estimated 50% increase in the adult population of endangered humpback chub (Gila cypha) between 2001 and 2008, following previous decline; (ii) a 90% decrease in non-native rainbow trout (Oncorhynchus mykiss), which are known to compete with and prey on native fish, as a result of removal experiments; and (iii) the widespread reappearance of sandbars in response to an experimental high-flow release of dam water in March 2008.Although substantial progress has been made, the Program faces several immediate challenges. These include: (i) defining specific, measurable objectives and desired future conditions for important natural, cultural and recreational attributes to inform science and management decisions; (ii) implementing structural and operational changes to improve collaboration among stakeholders; (iii) establishing a long-term experimental programme and management plan; and (iv) securing long-term funding for monitoring programmes to assess ecosystem and other responses to management actions. Addressing these challenges and building on recent progress will require strong and consistent leadership from the US Department of the Interior

Colorado River sediment transport: 1. Natural sediment supply limitation and the influence of Glen Canyon Dam

USGS Publications Warehouse

Topping, David J.; Rubin, David M.; Vierra, L.E.

2000-01-01

Analyses of flow, sediment‐transport, bed‐topographic, and sedimentologic data suggest that before the closure of Glen Canyon Dam in 1963, the Colorado River in Marble and Grand Canyons was annually supply‐limited with respect to fine sediment (i.e., sand and finer material). Furthermore, these analyses suggest that the predam river in Glen Canyon was not supply‐limited to the same degree and that the degree of annual supply limitation increased near the head of Marble Canyon. The predam Colorado River in Grand Canyon displays evidence of four effects of supply limitation: (1) seasonal hysteresis in sediment concentration, (2) seasonal hysteresis in sediment grain size coupled to the seasonal hysteresis in sediment concentration, (3) production of inversely graded flood deposits, and (4∥ development or modification of a lag between the time of a flood peak and the time of either maximum or minimum (depending on reach geometry) bed elevation. Analyses of sediment budgets provide additional support for the interpretation that the predam river was annually supply‐limited with respect to fine sediment, but it was not supply‐limited with respect to fine sediment during all seasons. In the average predam year, sand would accumulate and be stored in Marble Canyon and upper Grand Canyon for 9 months of the year (from July through March) when flows were dominantly below 200–300 m3/s; this stored sand was then eroded during April through June when flows were typically higher. After closure of Glen Canyon Dam, because of the large magnitudes of the uncertainties in the sediment budget, no season of substantial sand accumulation is evident. Because most flows in the postdam river exceed 200–300 m3/s, substantial sand accumulation in the postdam river is unlikely.

Sediment Transport During Three Controlled-Flood Experiments on the Colorado River Downstream from Glen Canyon Dam, with Implications for Eddy-Sandbar Deposition in Grand Canyon National Park

USGS Publications Warehouse

Topping, David J.; Rubin, David M.; Grams, Paul E.; Griffiths, Ronald E.; Sabol, Thomas A.; Voichick, Nicholas; Tusso, Robert B.; Vanaman, Karen M.; McDonald, Richard R.

2010-01-01

Three large-scale field experiments were conducted on the Colorado River downstream from Glen Canyon Dam in 1996, 2004, and 2008 to evaluate whether artificial (that is, controlled) floods released from the dam could be used in conjunction with the sand supplied by downstream tributaries to rebuild and sustainably maintain eddy sandbars in the river in Grand Canyon National Park. Higher suspended-sand concentrations during a controlled flood will lead to greater eddy-sandbar deposition rates. During each controlled flood experiment, sediment-transport and bed-sediment data were collected to evaluate sediment-supply effects on sandbar deposition. Data collection substantially increased in spatial and temporal density with each subsequent experiment. The suspended- and bed-sediment data collected during all three controlled-flood experiments are presented and analyzed in this report. Analysis of these data indicate that in designing the hydrograph of a controlled flood that is optimized for sandbar deposition in a given reach of the Colorado River, both the magnitude and the grain size of the sand supply must be considered. Because of the opposing physical effects of bed-sand area and bed-sand grain size in regulating suspended-sand concentration, larger amounts of coarser sand on the bed can lead to lower suspended-sand concentrations, and thus lower rates of sandbar deposition, during a controlled flood than can lesser amounts of finer sand on the bed. Although suspended-sand concentrations were higher at all study sites during the 2008 controlled-flood experiment (CFE) than during either the 1996 or 2004 CFEs, these higher concentrations were likely associated with more sand on the bed of the Colorado River in only lower Glen Canyon. More sand was likely present on the bed of the river in Grand Canyon during the 1996 CFE than during either the 2004 or 2008 CFEs. The question still remains as to whether sandbars can be sustained in the Colorado River in Grand

American Canyon Sanitary Landfill Operation Regulatory Permit Application, Napa County, California, Public Notice 9297-29R.

DTIC Science & Technology

1982-03-01

control and containment levees on land located along the east bank of the Napa River in southern Napa County, California. 2. In response to the National...approximately 60 acres with construction of flood protection and containment levees around these areas. The estimated refuse and earthwork volumes are...of flood control and containment levees) of restorable wetland being permanently converted to upland. f. provide nuisance factors associated with

76 FR 23623 - Backcountry Management Plan, Environmental Impact Statement, Grand Canyon National Park, Arizona

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-27

... DEPARTMENT OF THE INTERIOR National Park Service Backcountry Management Plan, Environmental Impact Statement, Grand Canyon National Park, Arizona AGENCY: National Park Service, Department of the Interior..., Grand Canyon National Park. SUMMARY: Pursuant to the National Environmental Policy Act of 1969 (42 U.S.C...

Fluctuating Helical Asymmetry and Morphology of Snails (Gastropoda) in Divergent Microhabitats at ‘Evolution Canyons I and II,’ Israel

PubMed Central

Raz, Shmuel; Schwartz, Nathan P.; Mienis, Hendrik K.; Nevo, Eviatar; Graham, John H.

2012-01-01

Background Developmental instability of shelled gastropods is measured as deviations from a perfect equiangular (logarithmic) spiral. We studied six species of gastropods at ‘Evolution Canyons I and II’ in Carmel and the Galilee Mountains, Israel, respectively. The xeric, south-facing, ‘African’ slopes and the mesic, north-facing, ‘European’ slopes have dramatically different microclimates and plant communities. Moreover, ‘Evolution Canyon II’ receives more rainfall than ‘Evolution Canyon I.’ Methodology/Principal Findings We examined fluctuating asymmetry, rate of whorl expansion, shell height, and number of rotations of the body suture in six species of terrestrial snails from the two ‘Evolution Canyons.’ The xeric ‘African’ slope should be more stressful to land snails than the ‘European’ slope, and ‘Evolution Canyon I’ should be more stressful than ‘Evolution Canyon II.’ Only Eopolita protensa jebusitica showed marginally significant differences in fluctuating helical asymmetry between the two slopes. Contrary to expectations, asymmetry was marginally greater on the ‘European’ slope. Shells of Levantina spiriplana caesareana at ‘Evolution Canyon I,’ were smaller and more asymmetric than those at ‘Evolution Canyon II.’ Moreover, shell height and number of rotations of the suture were greater on the north-facing slopes of both canyons. Conclusions/Significance Our data is consistent with a trade-off between drought resistance and thermoregulation in snails; Levantina was significantly smaller on the ‘African’ slope, for increasing surface area and thermoregulation, while Eopolita was larger on the ‘African’ slope, for reducing water evaporation. In addition, ‘Evolution Canyon I’ was more stressful than Evolution Canyon II’ for Levantina. PMID:22848631

Influence of local parameters on the dispersion of traffic-related pollutants within street canyons

NASA Astrophysics Data System (ADS)

Karra, Styliani; Malki-Epshtein, Liora; Martin Hyde Collaboration

2011-11-01

Ventilation within urban cities and street canyons and the associated air quality is a problem of increasing interest in the last decades. It is important for to minimise exposure of the population to traffic-related pollutants at street level. The residence time of pollutants within the street canyons depends on the meteorological conditions such as wind speed and direction, geometry layout and local parameters (position of traffic lane within the street). An experimental study was carried out to investigate the influence of traffic lane position on the dispersion of traffic-related pollutants within different street canyons geometries: symmetrical (equal building heights on both sides of the street), non-symmetrical (uniform building heights but lower on one side of the street) and heterogeneous (non-uniform building heights on both sides of the street) under constant meteorological conditions. Laboratory experiments were carried out within a water channel and simultaneous measurements of velocity field and concentration scalar levels within and above the street canyons using PIV and PLIF techniques. Traffic -related emissions were simulated using a line emission source. Two positions were examined for all street geometries: line emission source was placed in the centre of the street canyon; line emission source was placed off the centre of the street. TSI Incorporated.

DRAFT LANDSAT DATA MOSAIC: MONTGOMERY COUNTY, TEXAS; HARRIS COUNTY, TEXAS; FORT BEND COUNTY, TEXAS; BRAZORIA COUNTY, TEXAS; GALVESTON COUNTY, TEXAS

EPA Science Inventory

This is a draft Landsat Data Mosaic, which contains remote sensing information for Montgomery County, Texas Harris County, Texas Fort Bend County, Texas Brazoria County, Texas Galveston County, and Texas Imagery dates on the following dates: October 6, 1999 and September 29, 200...

Rose Canyon Sustainable Aquaculture Project, San Diego, CA

EPA Pesticide Factsheets

Documents related to EPA's preparation of an Environmental Assessment (EA) to analyze the potential impacts related to the issuance of a National Pollutant Discharge Elimination System (NPDES) permit for the Rose Canyon Sustainable Aquaculture Project.

Food-web dynamics and isotopic niches in deep-sea communities residing in a submarine canyon and on the adjacent open slopes

USGS Publications Warehouse

Demopoulos, Amanda W.J.; McClain-Counts, Jennifer; Ross, Steve W.; Brooke, Sandra; Mienis, Furu

2017-01-01

Examination of food webs and trophic niches provide insights into organisms' functional ecology, yet few studies have examined trophodynamics within submarine canyons, where the interaction of canyon morphology and oceanography influences habitat provision and food deposition. Using stable isotope analysis and Bayesian ellipses, we documented deep-sea food-web structure and trophic niches in Baltimore Canyon and the adjacent open slopes in the US Mid-Atlantic Region. Results revealed isotopically diverse feeding groups, comprising approximately 5 trophic levels. Regression analysis indicated that consumer isotope data are structured by habitat (canyon vs. slope), feeding group, and depth. Benthic feeders were enriched in 13C and 15N relative to suspension feeders, consistent with consuming older, more refractory organic matter. In contrast, canyon suspension feeders had the largest and more distinct isotopic niche, indicating they consume an isotopically discrete food source, possibly fresher organic material. The wider isotopic niche observed for canyon consumers indicated the presence of feeding specialists and generalists. High dispersion in δ13C values for canyon consumers suggests that the isotopic composition of particulate organic matter changes, which is linked to depositional dynamics, resulting in discrete zones of organic matter accumulation or resuspension. Heterogeneity in habitat and food availability likely enhances trophic diversity in canyons. Given their abundance in the world's oceans, our results from Baltimore Canyon suggest that submarine canyons may represent important havens for trophic diversity.

Effectiveness of green infrastructure for improvement of air quality in urban street canyons.

PubMed

Pugh, Thomas A M; Mackenzie, A Robert; Whyatt, J Duncan; Hewitt, C Nicholas

2012-07-17

Street-level concentrations of nitrogen dioxide (NO(2)) and particulate matter (PM) exceed public health standards in many cities, causing increased mortality and morbidity. Concentrations can be reduced by controlling emissions, increasing dispersion, or increasing deposition rates, but little attention has been paid to the latter as a pollution control method. Both NO(2) and PM are deposited onto surfaces at rates that vary according to the nature of the surface; deposition rates to vegetation are much higher than those to hard, built surfaces. Previously, city-scale studies have suggested that deposition to vegetation can make a very modest improvement (<5%) to urban air quality. However, few studies take full account of the interplay between urban form and vegetation, specifically the enhanced residence time of air in street canyons. This study shows that increasing deposition by the planting of vegetation in street canyons can reduce street-level concentrations in those canyons by as much as 40% for NO(2) and 60% for PM. Substantial street-level air quality improvements can be gained through action at the scale of a single street canyon or across city-sized areas of canyons. Moreover, vegetation will continue to offer benefits in the reduction of pollution even if the traffic source is removed from city centers. Thus, judicious use of vegetation can create an efficient urban pollutant filter, yielding rapid and sustained improvements in street-level air quality in dense urban areas.

Deep-sea bacterial communities in sediments and guts of deposit-feeding holothurians in Portuguese canyons (NE Atlantic)

NASA Astrophysics Data System (ADS)

Amaro, Teresa; Witte, Harry; Herndl, Gerhard J.; Cunha, Marina R.; Billett, David S. M.

2009-10-01

Deposit-feeding holothurians often dominate the megafauna in bathyal deep-sea settings, in terms of both abundance and biomass. Molpadia musculus is particularly abundant at about 3400 m depth in the Nazaré Canyon on the NE Atlantic Continental Margin. However, these high abundances are unusual for burrowing species at this depth. The objective of this research was to understand the reasons of the massive occurrence of these molpadiid holothurians in the Nazaré Canyon. To address this question we investigated possible trophic interactions with bacteria at sites where the organic content of the sediment was different (Setúbal and Cascais Canyons, NE Atlantic Continental Margin). The molecular fingerprinting technique of Denaturing Gradient Gel Electrophoresis (DGGE) with band sequencing, combined with non-metric multi-dimensional scaling and statistical analyses, was used to compare the bacterial community diversity in canyon sediments and holothurian gut contents. Our results suggest that M. musculus does not need to develop a specialised gut bacterial community to aid digestion where the sediment is rich in organic matter (Nazaré Canyon); in contrast, such a community may be developed where the sediment is poorer in organic matter (Cascais Canyon).

Formation of Box Canyon, Idaho, by megaflood: implications for seepage erosion on Earth and Mars.

PubMed

Lamb, Michael P; Dietrich, William E; Aciego, Sarah M; Depaolo, Donald J; Manga, Michael

2008-05-23

Amphitheater-headed canyons have been used as diagnostic indicators of erosion by groundwater seepage, which has important implications for landscape evolution on Earth and astrobiology on Mars. Of perhaps any canyon studied, Box Canyon, Idaho, most strongly meets the proposed morphologic criteria for groundwater sapping because it is incised into a basaltic plain with no drainage network upstream, and approximately 10 cubic meters per second of seepage emanates from its vertical headwall. However, sediment transport constraints, 4He and 14C dates, plunge pools, and scoured rock indicate that a megaflood (greater than 220 cubic meters per second) carved the canyon about 45,000 years ago. These results add to a growing recognition of Quaternary catastrophic flooding in the American northwest, and may imply that similar features on Mars also formed by floods rather than seepage erosion.

33 CFR 165.1155 - Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Nuclear Power Plant, Avila Beach, California. 165.1155 Section 165.1155 Navigation and Navigable Waters... Coast Guard District § 165.1155 Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach... surface to bottom, within a 2,000 yard radius of Diablo Canyon Nuclear Power Plant centered at position 35...

33 CFR 165.1155 - Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Nuclear Power Plant, Avila Beach, California. 165.1155 Section 165.1155 Navigation and Navigable Waters... Coast Guard District § 165.1155 Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach... surface to bottom, within a 2,000 yard radius of Diablo Canyon Nuclear Power Plant centered at position 35...

33 CFR 165.1155 - Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Nuclear Power Plant, Avila Beach, California. 165.1155 Section 165.1155 Navigation and Navigable Waters... Coast Guard District § 165.1155 Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach... surface to bottom, within a 2,000 yard radius of Diablo Canyon Nuclear Power Plant centered at position 35...

33 CFR 165.1155 - Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Nuclear Power Plant, Avila Beach, California. 165.1155 Section 165.1155 Navigation and Navigable Waters... Coast Guard District § 165.1155 Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach... surface to bottom, within a 2,000 yard radius of Diablo Canyon Nuclear Power Plant centered at position 35...

33 CFR 165.1155 - Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Nuclear Power Plant, Avila Beach, California. 165.1155 Section 165.1155 Navigation and Navigable Waters... Coast Guard District § 165.1155 Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach... surface to bottom, within a 2,000 yard radius of Diablo Canyon Nuclear Power Plant centered at position 35...

Atmospheric Fragmentation of the Canyon Diablo Meteoroid

NASA Technical Reports Server (NTRS)

Pierazzo, E.; Artemieva, N. A.

2005-01-01

About 50 kyr ago the impact of an iron meteoroid excavated Meteor Crater, Arizona, the first terrestrial structure widely recognized as a meteorite impact crater. Recent studies of ballistically dispersed impact melts from Meteor Crater indicate a compositionally unusually heterogeneous impact melt with high SiO2 and exceptionally high (10 to 25% on average) levels of projectile contamination. These are observations that must be explained by any theoretical modeling of the impact event. Simple atmospheric entry models for an iron meteorite similar to Canyon Diablo indicate that the surface impact speed should have been around 12 km/s [Melosh, personal comm.], not the 15-20 km/s generally assumed in previous impact models. This may help explaining the unusual characteristics of the impact melt at Meteor Crater. We present alternative initial estimates of the motion in the atmosphere of an iron projectile similar to Canyon Diablo, to constraint the initial conditions of the impact event that generated Meteor Crater.

Effects of three high-flow experiments on the Colorado River ecosystem downstream from Glen Canyon Dam, Arizona

USGS Publications Warehouse

Melis, Theodore S.

2011-01-01

Three high-flow experiments (HFEs) were conducted by the U.S. Department of the Interior at Glen Canyon Dam, Arizona, in March 1996, November 2004, and March 2008. These experiments, also known as artificial or controlled floods, were large-volume, scheduled releases of water from Glen Canyon Dam that were designed to mimic some aspects of pre-dam Colorado River seasonal flooding. The goal of these experiments was to determine whether high flows could be used to benefit important physical and biological resources in Glen Canyon National Recreation Area and Grand Canyon National Park that had been affected by the operation of Glen Canyon Dam. Efforts such as HFEs that seek to maintain and restore downstream resources are undertaken by the U.S. Department of the Interior under the auspices of the Grand Canyon Protection Act of 1992 (GCPA; title XVIII, secs. 1801-1809, of Public Law 102-575). Scientists conducted a wide range of monitoring and research activities before, during, and after the experiments. Initially, research efforts focused on whether HFEs could be used to rebuild and maintain Grand Canyon sandbars, which provide camping beaches for hikers and whitewater rafters, create habitats potentially used by native fish and other wildlife, and are the source of windborne sand that may help to protect some archaeological resources from weathering and erosion. As scientists gained a better understanding of how HFEs affect the physical environment, research efforts expanded to include additional investigations about the effects of HFEs on biological resources, such as native fishes, nonnative sports fishes, riverside vegetation, and the aquatic food web. The chapters that follow summarize and synthesize for decisionmakers and the public what has been learned about HFEs to provide a framework for implementing similar future experiments. This report is a product of the Glen Canyon Dam Adaptive Management Program (GCDAMP), a Federal initiative authorized to ensure

Fluid mechanical dispersion of airborne pollutants inside urban street canyons subjecting to multi-component ventilation and unstable thermal stratifications.

PubMed

Mei, Shuo-Jun; Liu, Cheng-Wei; Liu, Di; Zhao, Fu-Yun; Wang, Han-Qing; Li, Xiao-Hong

2016-09-15

The pedestrian level pollutant transport in street canyons with multiple aspect ratios (H/W) is numerically investigated in the present work, regarding of various unstable thermal stratification scenarios and plain surrounding. Non-isothermal turbulent wind flow, temperature field and pollutant spread within and above the street canyons are solved by the realizable k-ε turbulence model along with the enhanced wall treatment. One-vortex flow regime is observed for shallow canyons with H/W=0.5, whereas multi-vortex flow regime is observed for deep canyons with H/W=2.0. Both one-vortex and multi-vortex regimes could be observed for the street canyons with H/W=1.0, where the secondary vortex could be initiated by the flow separation and intensified by unstable thermal stratification. Air exchange rate (AER) and pollutant retention time are adopted to respectively evaluate the street canyon ventilation and pollutant removal performance. A second-order polynomial functional relationship is established between AER and Richardson number (Ri). Similar functional relationship could be established between retention time and Ri, and it is only valid for canyons with one-vortex flow regime. In addition, retention time could be prolonged abruptly for canyons with multi-vortex flow regime. Very weak secondary vortex is presented at the ground level of deep canyons with mild stratification, where pollutants are highly accumulated. However, with the decrease of Ri, pollutant concentration adjacent to the ground reduces accordingly. Present research could be applied to guide the urban design and city planning for enhancing pedestrian environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Seven years of geomorphic change in the head of Monterey Canyon, CA: Steady state equilibrium or monotonic change?

NASA Astrophysics Data System (ADS)

Smith, D. P.; Kvitek, R. G.; Ross, E.; Iampietro, P.; Paull, C. K.; Sandersfeld, M.

2010-12-01

The head of Monterey submarine canyon has been surveyed with high-precision multibeam sonar at least once each year since September 2002. This poster provides a summary of changes between September 2002 and September 2008. Data were collected with a variety of Reson mulitbeam sonar heads, and logged with an ISIS data acquisition system. Vessel attitude was corrected using an Applanix POS MV equipped with an auxillary C-Nav 2050 GPS receiver. Data were processed and filtered and cleaned in Caris HIPS. Depth changes for various time spans were determined through raster subtraction of pairs of 3-m resolution bathymetric grids in ArcMap. The depth change analyses focused on the canyon floor, except where a landslide occurred on a wall, and where obvious gullying near the headwall had occurred during the time of our study. Canyon walls were generally excluded from analysis. The analysis area was 1,414,240 sq meters. The gross changes between 2002 and 2008 include net erosion of 2,300,000 m^3 +/- 800,000 m^3 of material from the canyon. The annualized rate of net sediment loss from this time frame agrees within an order of magnitude with our previously published estimates from earlier (shorter) time frames, so the erosion events seem to be moderate magnitude and frequent, rather than infrequent and catastrophic. The greatest sediment loss appears to be from lateral erosion of channel-bounding terraces rather than deepening or scouring of the existing channel axis. A single landslide event that occurred in summer 2003 had an initial slide scar (void) volume of 71,000 m^3. The scar was observed to increase annually, and had grown to approximately 96,000 m^3 by 2008. The initial slide was too small to be tsunamigenic. In contrast to the monotonic canyon axis widening, the shoreward terminus of the canyon (canyon lip) appears to be in steady state equilibrium with sediment supply entering the canyon from the littoral zone. The lip position, indicated by the clearly defined

Simulations of the impacts of building height layout on air quality in natural-ventilated rooms around street canyons.

PubMed

Yang, Fang; Zhong, Ke; Chen, Yonghang; Kang, Yanming

2017-10-01

Numerical simulations were conducted to investigate the effects of building height ratio (i.e., HR, the height ratio of the upstream building to the downstream building) on the air quality in buildings beside street canyons, and both regular and staggered canyons were considered for the simulations. The results show that the building height ratio affects not only the ventilation fluxes of the rooms in the downstream building but also the pollutant concentrations around the building. The parameter, outdoor effective source intensity of a room, is then proposed to calculate the amount of vehicular pollutants that enters into building rooms. Smaller value of this parameter indicates less pollutant enters the room. The numerical results reveal that HRs from 2/7 to 7/2 are the favorable height ratios for the regular canyons, as they obtain smaller values than the other cases. While HR values of 5/7, 7/7, and 7/5 are appropriate for staggered canyons. In addition, in terms of improving indoor air quality by natural ventilation, the staggered canyons with favorable HR are better than those of the regular canyons.

Determining the flux of methane into Hudson Canyon at the edge of methane clathrate hydrate stability

USGS Publications Warehouse

Weinsten, A.; Navarrete, L; Ruppel, Carolyn D.; Weber, T.C.; Leonte, M.; Kellermann, M.; Arrington, E.; Valentine, D.L.; Scranton, M.L; Kessler, John D.

2016-01-01

Methane seeps were investigated in Hudson Canyon, the largest shelf-break canyon on the northern US Atlantic Margin. The seeps investigated are located at or updip of the nominal limit of methane clathrate hydrate stability. The acoustic identification of bubble streams was used to guide water column sampling in a 32 km2 region within the canyon's thalweg. By incorporating measurements of dissolved methane concentration with methane oxidation rates and current velocity into a steady-state box model, the total emission of methane to the water column in this region was estimated to be 12 kmol methane per day (range: 6 – 24 kmol methane per day). These analyses suggest this methane is largely retained inside the canyon walls below 300 m water depth, and that it is aerobically oxidized to near completion within the larger extent of Hudson Canyon. Based on estimated methane emissions and measured oxidation rates, the oxidation of this methane to dissolved CO2 is expected to have minimal influences on seawater pH. This article is protected by copyright. All rights reserved.

Determining the flux of methane into Hudson Canyon at the edge of methane clathrate hydrate stability

NASA Astrophysics Data System (ADS)

Weinstein, Alexander; Navarrete, Luis; Ruppel, Carolyn; Weber, Thomas C.; Leonte, Mihai; Kellermann, Matthias Y.; Arrington, Eleanor C.; Valentine, David L.; Scranton, Mary I.; Kessler, John D.

2016-10-01

Methane seeps were investigated in Hudson Canyon, the largest shelf-break canyon on the northern U.S. Atlantic Margin. The seeps investigated are located at or updip of the nominal limit of methane clathrate hydrate stability. The acoustic identification of bubble streams was used to guide water column sampling in a 32 km2 region within the canyon's thalweg. By incorporating measurements of dissolved methane concentration with methane oxidation rates and current velocity into a steady state box model, the total emission of methane to the water column in this region was estimated to be 12 kmol methane per day (range: 6-24 kmol methane per day). These analyses suggest that the emitted methane is largely retained inside the canyon walls below 300 m water depth, and that it is aerobically oxidized to near completion within the larger extent of Hudson Canyon. Based on estimated methane emissions and measured oxidation rates, the oxidation of this methane to dissolved CO2 is expected to have minimal influences on seawater pH.

Mars Odyssey View of Morning Clouds in Canyon

NASA Image and Video Library

2016-04-05

Light blue clouds fill Coprates Chasma on Mars, part of Valles Marineris, the vast Grand Canyon of Mars. The clouds are mostly ice crystals and they appear blue in color in this image from NASA Mars Odyssey.

UV Radiation in an Urban Canyon in Southeast Queensland

NASA Astrophysics Data System (ADS)

McKinley, A. R.; Moore, M. R.; Kimlin, M. G.

2006-12-01

Ultraviolet radiation (UV) has the possibility to both harm and to benefit human beings when unprotected exposure occurs. After receiving small amounts of UV our bodies begin to synthesise vitamin D, which is essential for maintaining healthy bones, however excessive UV exposure can result in a variety of damaging outcomes ranging from sunburn to skin cancer and cataracts. For this reason it is very important to understand the different environments in which people encounter UV so as to better prepare the public to make smart and healthy sun exposure decisions. Each day more and more people are moving into large cities around the world and spending their time inside the urban canyon, however UV measurements are generally taken at scientific stations in open areas or on top of tall buildings, meaning that at times the environmental characteristics measured may not accurately represent those found at street-level in these highly urbanized areas. Urban canyons are home to both very tall buildings and tropospheric air pollution, each of which reduces the amount of UV reaching street-level. This study measured the varying difference between UV measurements taken at street-level and at a standard UV monitoring site on top of a building outside of the urban canyon. Investigation was conducted in the central business district (CBD) of Brisbane, Australia, which models the CBDs of large cities around the world in that it boasts a great number of tall buildings, including many skyscrapers. Data was collected under clear sky conditions at five different street-level sites in the CBD (on either side of two streets running perpendicular to one another (four sites) and in a public square) and then compared to that obtained on the same day at the Queensland University of Technology's Australian Sun and Health Research Laboratory (ASHRL), which is located 2.5 kilometres outside Brisbane's CBD. Minimum erythemal dose (MED) data was collected at each location and it was found that

Perspective view over the Grand Canyon, Arizona

NASA Technical Reports Server (NTRS)

2001-01-01

This simulated true color perspective view over the Grand Canyon was created from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data acquired on May 12, 2000. The Grand Canyon Village is in the lower foreground; the Bright Angel Trail crosses the Tonto Platform, before dropping down to the Colorado Village and then to the Phantom Ranch (green area across the river). Bright Angel Canyon and the North Rim dominate the view. At the top center of the image the dark blue area with light blue haze is an active forest fire.

ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

Size: 5 km in foreground to 40 km Location: 36.3 degrees north latitude, 112 degrees west longitude Orientation: North-northeast at top Original Data Resolution: ASTER 15 meters Dates Acquired: May 12, 2000

Thermal comfort in an east-west oriented street canyon in Freiburg (Germany) under hot summer conditions

NASA Astrophysics Data System (ADS)

Ali-Toudert, F.; Mayer, H.

2007-01-01

Field-measurements were conducted in an urban street canyon with an east-west orientation, and a height-to-width ratio H/W = 1 during cloudless summer weather in 2003 in Freiburg, Germany. This experimental work adds to the knowledge available on the microclimate of an urban canyon and its impact on human comfort. Air temperature T a , air humidity VP, wind speed v and direction dd were measured continuously. All short-wave and long-wave radiation fluxes from the 3D surroundings were also measured. The degree of comfort was defined in terms of physiologically equivalent temperature (PET). Furthermore, the data gathered within the canyon were compared to data collected by a permanent urban climate station with the aim of furthering the understanding of microclimatic changes due to street geometry. Changes in the meteorological variables T a , v and dd in the canyon in comparison to an unobstructed roof level location were found to be in good agreement with previous studies, i.e., a small increase of T a in the canyon adjacent to irradiated surfaces, and a good correlation of v and dd between canyon and roof levels. The daily dynamics of canyon facet irradiances and their impacts on the heat gained by a pedestrian were strongly dependent on street geometry and orientation. Thermal stress was mostly attributable to solar exposure. Under cloudless summer weather, a standing body was found to absorb, on average, 74% of heat in the form of long-wave irradiance and 26% as short-wave irradiance. Shading the pedestrian as well as the surrounding surfaces is, hence, the first strategy in mitigating heat stress in summer under hot conditions.

Most Detailed Direct Measurements Yet of Turbidity Currents in the Deep Ocean: Monterey Coordinated Canyon Experiment

NASA Astrophysics Data System (ADS)

Paull, C. K.; Anderson, K.; Barry, J. P.; Caress, D. W.; Chaffey, M. R.; Gales, J. A.; Gwiazda, R.; Kieft, B.; Lundsten, E. M.; Maier, K. L.; McCann, M. P.; McGann, M.; O'Reilly, T. C.; Parsons, D. R.; Rosenberger, K. J.; Sumner, E.; Talling, P. J.; Xu, J.

2016-12-01

Submarine sediment gravity flows (turbidity currents) are among the most important sediment transport processes on Earth, yet there are remarkably few direct measurements of these events in action. The ongoing multi-institution Coordinated Canyon Experiment (CCE) is providing detailed measurements of turbidity currents using multiple sensors and sediment traps deployed in the axis of Monterey Canyon, offshore California, in 6-month long deployments from October 2015 to April 2017 together with seafloor sampling and repeated mapping of seafloor morphology. No previous study has deployed such a dense array of sensors along a turbidity current pathway. Instrumentation includes: an array of 6 moorings carrying downward looking acoustic Doppler current profilers (ADCP) and sediment traps distributed along the canyon axis from 270 to 1,850 m water depth; a benthic instrument node at 1,840 m holding ADCPs of three different frequencies recording on a common time base, as well as salinity, temperature, and turbidity sensors; a McLane profiler at 1,830 m monitoring the lower 500 m of the water column; an array of benthic event detectors (smart boulders) that record their transport within the base of a flow; and precision triangulation beacons to assess creep within the canyon floor. Repeated mapping of the canyon floor at nested grid resolutions ranging from 1-m to 1-cm is being conducted to understand changes in canyon floor morphology. The first 6-month long deployment has been completed and 8 sediment transport events recorded. Seven of these events were restricted to <520 m water depths. However, on January 15th 2016 a sediment-laden turbidity flow ran out for >50 km from <279 m to >1,860 m water depth with an average velocity of 5.4 m/sec. Individual moorings and instruments moved down-canyon up to 7.8 km during this event. The novel instrument array and mapping tools have successfully recorded the down-canyon evolution of the powerful flow in spectacular detail.

A numerical study of air pollutant dispersion with bimolecular chemical reactions in an urban street canyon using large-eddy simulation

NASA Astrophysics Data System (ADS)

Kikumoto, Hideki; Ooka, Ryozo

2012-07-01

A large-eddy simulation is performed on a turbulent dispersion of chemically reactive air pollutants in a two-dimensional urban street canyon with an aspect ratio of 1.0. Nitrogen monoxide emitted from a line-source set on the bottom of the street canyon disperses and reacts with Ozone included in a free stream. The reactions have significant influences on the concentrations of pollutants in the canyon space, and they increase the concentrations of the reaction products relative to of the concentrations of the reactants. The transport of air pollutants through a free shear layer above the canyon is closely related to the structure of the turbulence. Gases in the canyon are mainly exhausted when low-speed regions appear above the canyon. In contrast, pollutants in the free stream flow into the canyon with high-speed fluid bodies. Consequently, the correlation between the time fluctuations of the reactants' concentrations strongly affects the reaction rates in the region near the free shear layer. In this calculation, the correlation term reaches to a value of 20% of the mean reaction rate at a maximum there.

Spatial scale-dependent habitat heterogeneity influences submarine canyon macrofaunal abundance and diversity off the Main and Northwest Hawaiian Islands

NASA Astrophysics Data System (ADS)

De Leo, Fabio C.; Vetter, Eric W.; Smith, Craig R.; Rowden, Ashley A.; McGranaghan, Matthew

2014-06-01

The mapping of biodiversity on continental margins on landscape scales is highly relevant to marine spatial planning and conservation. Submarine canyons are widespread topographic features on continental and island margins that enhance benthic biomass across a range of oceanic provinces and productivity regimes. However, it remains unclear whether canyons enhance faunal biodiversity on landscape scales relevant to marine protected area (MPA) design. Furthermore, it is not known which physical attributes and heterogeneity metrics can provide good surrogates for large-scale mapping of canyon benthic biodiversity. To test mechanistic hypotheses evaluating the role of different canyon-landscape attributes in enhancing benthic biodiversity at different spatial scales we conducted 34 submersible dives in six submarine canyons and nearby slopes in the Hawaiian archipelago, sampling infaunal macrobenthos in a depth-stratified sampling design. We employed multivariate multiple regression models to evaluate sediment and topographic heterogeneity, canyon transverse profiles, and overall water mass variability as potential drivers of macrobenthic community structure and species richness. We find that variables related to habitat heterogeneity at medium (0.13 km2) and large (15-33 km2) spatial scales such as slope, backscatter reflectivity and canyon transverse profiles are often good predictors of macrobenthic biodiversity, explaining 16-30% of the variance. Particulate organic carbon (POC) flux and distance from shore are also important variables, implicating food supply as a major predictor of canyon biodiversity. Canyons off the high Main Hawaiian Islands (Oahu and Moloka'i) are significantly affected by organic enrichment, showing enhanced infaunal macrobenthos abundance, whereas this effect is imperceptible around the low Northwest Hawaiian Islands (Nihoa and Maro Reef). Variable canyon alpha-diversity and high rates of species turnover (beta-diversity), particularly for

Characterizing local traffic contributions to particulate air pollution in street canyons using mobile monitoring techniques

NASA Astrophysics Data System (ADS)

Zwack, Leonard M.; Paciorek, Christopher J.; Spengler, John D.; Levy, Jonathan I.

2011-05-01

Traffic within urban street canyons can contribute significantly to ambient concentrations of particulate air pollution. In these settings, it is challenging to separate within-canyon source contributions from urban and regional background concentrations given the highly variable and complex emissions and dispersion characteristics. In this study, we used continuous mobile monitoring of traffic-related particulate air pollutants to assess the contribution to concentrations, above background, of traffic in the street canyons of midtown Manhattan. Concentrations of both ultrafine particles (UFP) and fine particles (PM 2.5) were measured at street level using portable instruments. Statistical modeling techniques accounting for autocorrelation were used to investigate the presence of spatial heterogeneity of pollutant concentrations as well as to quantify the contribution of within-canyon traffic sources. Measurements were also made within Central Park, to examine the impact of offsets from major roadways in this urban environment. On average, an approximate 11% increase in concentrations of UFP and 8% increase in concentrations of PM 2.5 over urban background was estimated during high-traffic periods in street canyons as opposed to low traffic periods. Estimates were 8% and 5%, respectively, after accounting for temporal autocorrelation. Within Central Park, concentrations were 40% higher than background (5% after accounting for temporal autocorrelation) within the first 100 m from the nearest roadway for UFP, with a smaller but statistically significant increase for PM 2.5. Our findings demonstrate the viability of a mobile monitoring protocol coupled with spatiotemporal modeling techniques in characterizing local source contributions in a setting with street canyons.

Distribution and movement of humpback chub in the Colorado River, Grand Canyon, based on recaptures

USGS Publications Warehouse

Paukert, C.P.; Coggins, L.G.; Flaccus, C.E.

2006-01-01

Mark-recapture data from the federally endangered humpback chub Gila cypha in the Colorado River, Grand Canyon, were analyzed from 1989 to 2002 to determine large-scale movement patterns and distribution. A total of 14,674 recaptures from 7,127 unique fish were documented; 87% of the recaptures occurred in the same main-stem river reach or tributary as the original captures, suggesting restricted distribution by most fish. A total of 99% of all recaptures were from in and around the Little Colorado River (LCR), a tributary of the Colorado River and primary aggregation and spawning location of humpback chub in Grand Canyon. Time at liberty averaged 394 d, but some fish were recaptured near their main-stem capture location over 10 years later. Proportionally fewer large (>300-mm) humpback chub exhibited restricted distribution than small (<200-mm) fish. However, several fish did move more than 154 km throughout Grand Canyon between capture and recapture, suggesting that limited movement occurs throughout Grand Canyon. The majority of the recaptured fish remained in or returned to the LCR or the Colorado River near the LCR. Although many large-river fishes exhibit extensive migrations to fulfill their life history requirements, most of the humpback chub in Grand Canyon appear to remain in or come back to the LCR and LCR confluence across multiple sizes and time scales. Detecting trends in the overall abundance of this endangered fish in Grand Canyon can probably be accomplished by monitoring the area in and around the LCR.

A simple model for calculating air pollution within street canyons

NASA Astrophysics Data System (ADS)

Venegas, Laura E.; Mazzeo, Nicolás A.; Dezzutti, Mariana C.

2014-04-01

This paper introduces the Semi-Empirical Urban Street (SEUS) model. SEUS is a simple mathematical model based on the scaling of air pollution concentration inside street canyons employing the emission rate, the width of the canyon, the dispersive velocity scale and the background concentration. Dispersive velocity scale depends on turbulent motions related to wind and traffic. The parameterisations of these turbulent motions include two dimensionless empirical parameters. Functional forms of these parameters have been obtained from full scale data measured in street canyons at four European cities. The sensitivity of SEUS model is studied analytically. Results show that relative errors in the evaluation of the two dimensionless empirical parameters have less influence on model uncertainties than uncertainties in other input variables. The model estimates NO2 concentrations using a simple photochemistry scheme. SEUS is applied to estimate NOx and NO2 hourly concentrations in an irregular and busy street canyon in the city of Buenos Aires. The statistical evaluation of results shows that there is a good agreement between estimated and observed hourly concentrations (e.g. fractional bias are -10.3% for NOx and +7.8% for NO2). The agreement between the estimated and observed values has also been analysed in terms of its dependence on wind speed and direction. The model shows a better performance for wind speeds >2 m s-1 than for lower wind speeds and for leeward situations than for others. No significant discrepancies have been found between the results of the proposed model and that of a widely used operational dispersion model (OSPM), both using the same input information.

Physical and chemical characteristics of Knowles, Forgotten, and Moqui Canyons, and effects of recreational use on water quality, Lake Powell, Arizona and Utah

USGS Publications Warehouse

Hart, Robert J.; Taylor, Howard E.; Antweiler, Ronald C.; Fisk, Greg G.; Anderson, G.M.; Roth, D.A.; Flynn, Marilyn E.; Peart, D.B.; Truini, Margot; Barber, L.B.

2005-01-01

Side canyons of Lake Powell are the most popular recreation areas of the Glen Canyon National Recreation Area in Arizona and Utah. There are more than 90 side canyons that are tributaries to the main lake body of Lake Powell. Near Bullfrog and Halls Crossing marinas in Utah, visitors frequent Knowles, Forgotten, and Moqui Canyons to fish, boat, camp, and hike the sandstone formations for which Lake Powell is famous. Areas of recreational activity are greatest near beaches in side canyons. Emissions from houseboats, personal watercraft, speedboats, and from some nonboating recreational activities introduce contaminants to the lake and to beach areas. The U.S. Geological Survey documented concentrations of trace elements, volatile organic compounds, organic wastewater contaminants, and other byproducts of fuel-based contaminants in water and bed material in Knowles, Forgotten, and Moqui Canyons during the summers of 2001 and 2002. Field work was conducted during four trips when recreational use was at a minimum (before Memorial Day in May) and when it was at a maximum (near Labor Day in September). Knowles Canyon was treated as a control; therefore, public access by motorcraft was not permitted during the study. Electric-powered or oar-powered research boats were used to collect samples and measure properties in Knowles Canyon. Record-low reservoir elevations during 2000-2002 limited the availability of camping and day-use beaches in Forgotten and Moqui Canyons. Although more beach areas were exposed during this period, the steep slopes of the beaches made it difficult to use the beaches for camping purposes. Side canyon waters of Knowles, Forgotten, and Moqui Canyons were similarly stratified (physically and chemically) during the study from natural advective and convective reservoir processes. Metalimnetic oxygen minimas were observed in September 2001 and 2002 in the side canyons and the main body of Lake Powell. Chemical concentrations of several organic

Altered stimulation technique and fluid shows improved canyon sand production in Flowers West and Guest Units, Stonewall County, Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pai, V.J.

1978-01-01

In order to combat falling productivity and increased water production in the W. Flowers and Guest (Canyon Sand) fields, a new approach to stimulation technique and fluid had to be initiated. It was suspected that many pre-1975 frac jobs probably were lost into unproductive zones resulting in very little stimulation of the actual pay section. To combat this situation, the frac fluid was changed to a very high viscosity cross-linked CMC-based polymer gel. The base fluid was 2% KCl water treated with de-emulsifiers. A detailed computerized study was conducted to determine a near optimum treatment design. Fluid volumes were selectedmore » based on frac lengths, which provided the most economically feasible productivity increase ratios (J/J/sub 0/), and proppant concentrations were analyzed so as to afford the optimum permeability contrasts. Sand concentrations were increased, and 10-20 mesh sand was used.« less

Mineral resource potential map of the Chama River Canyon Wilderness and contiguous roadless area, Rio Arriba County, New Mexico

USGS Publications Warehouse

Ridgley, Jennie L.; Light, Thomas D.

1983-01-01

The Chama River Canyon Wilderness and Roadless Area have a moderate to high potential for the presence of small deposits of copper with associated uranium and silver. These deposits, as yet undetected, would occur in the Permian Cutler Formation and in the lower part of the Triassic Chinle Formation, rock units that are, for the most part, present only in the subsurface. The presence of these deposits is inferred because such deposits occur in rocks of equivalent age in adjacent areas. Gypsum, of probable minable quality and quantity, occurs throughout the area. Oil and gas are possibly present in Pennsylvanian strata in the subsurface, although no drilling in the study area has tested this hypothesis. Other commodities, including noncopper-related uranium, kaolinite, chromium, vanadium, manganese, and bitumen, although present locally in anomalous concentrations, do not appear to constitute potential resources for these commodities.

The Colorado River in the Grand Canyon.

ERIC Educational Resources Information Center

Speece, Susan

1991-01-01

An assessment of the water quality of the Colorado River in the Grand Canyon was made, using the following parameters: dissolved oxygen, water temperature, hydrogen ion concentration, total dissolved solids, turbidity, and ammonium/nitrogen levels. These parameters were used to provide some clue as to the "wellness" and stability of the…

Litter in submarine canyons off the west coast of Portugal

NASA Astrophysics Data System (ADS)

Mordecai, Gideon; Tyler, Paul A.; Masson, Douglas G.; Huvenne, Veerle A. I.

2011-12-01

Marine litter is of global concern and is present in all the world's oceans, including deep benthic habitats where the extent of the problem is still largely unknown. Litter abundance and composition were investigated using video footage and still images from 16 Remotely Operated Vehicle (ROV) dives in Lisbon, Setúbal, Cascais and Nazaré Canyons located west of Portugal. Litter was most abundant at sites closest to the coastline and population centres, suggesting the majority of the litter was land sourced. Plastic was the dominant type of debris, followed by fishing gear. Standardised mean abundance was 1100 litter items km -2, but was as high as 6600 litter items km -2 in canyons close to Lisbon. Although all anthropogenic material may be harmful to biota, debris was also used as a habitat by some macro-invertebrates. Litter composition and abundance observed in the canyons of the Portuguese margin were comparable to those seen in other deep sea areas around the world. Accumulation of litter in the deep sea is a consequence of human activities both on land and at sea. This needs to be taken into account in future policy decisions regarding marine pollution.

78 FR 3879 - Ochoco National Forest, Paulina Ranger District; Oregon; Fox Canyon Cluster Allotment Management...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-17

...; Fox Canyon Cluster Allotment Management Plan Project EIS AGENCY: Forest Service, USDA. ACTION: Notice... preparing an environmental impact statement (EIS) to analyze the effects of changing grazing management in four allotments on the Paulina Ranger District. The Fox Canyon Cluster project area is located...

75 FR 10308 - Fire Management Plan, Final Environmental Impact Statement, Record of Decision, Grand Canyon...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-05

... DEPARTMENT OF THE INTERIOR National Park Service Fire Management Plan, Final Environmental Impact... Statement for the Fire Management Plan, Grand Canyon National Park. SUMMARY: Pursuant to the National... the Record of Decision for the Fire Management Plan, Grand Canyon National Park, Arizona. On January...

Internal tidal currents in the Gaoping (Kaoping) Submarine Canyon

USGS Publications Warehouse

Lee, I.-H.; Wang, Y.-H.; Liu, J.T.; Chuang, W.-S.; Xu, Jie

2009-01-01

Data from five separate field experiments during 2000-2006 were used to study the internal tidal flow patterns in the Gaoping (formerly spelled Kaoping) Submarine Canyon. The internal tides are large with maximum interface displacements of about 200??m and maximum velocities of over 100cm/s. They are characterized by a first-mode velocity and density structure with zero crossing at about 100??m depth. In the lower layer, the currents increase with increasing depth. The density interface and the along-channel velocity are approximately 90?? out-of-phase, suggesting a predominant standing wave pattern. However, partial reflection is indicated as there is a consistent phase advance between sea level and density interface along the canyon axis. ?? 2008 Elsevier B.V. All rights reserved.

A study of sound absorption by street canyon boundaries and asphalt rubber concrete pavement

NASA Astrophysics Data System (ADS)

Drysdale, Graeme Robert

A sound field model, based on a classical diffusion equation, is extended to account for sound absorption in a diffusion parameter used to model sound energy in a narrow street canyon. The model accounts for a single sound absorption coefficient, separate accommodation coefficients and a combination of separate absorption and accommodation coefficients from parallel canyon walls. The new expressions are compared to the original formula through numerical simulations to reveal the effect of absorption on sound diffusion. The newly established analytical formulae demonstrate satisfactory agreement with their predecessor under perfect reflection. As well, the influence of the extended diffusion parameter on normalized sound pressure levels in a narrow street canyon is in agreement with experimental data. The diffusion parameters are used to model sound energy density in a street canyon as a function of the sound absorption coefficient of the street canyon walls. The acoustic and material properties of conventional and asphalt rubber concrete (ARC) pavement are also studied to assess how the crumb rubber content influences sound absorption in street canyons. The porosity and absolute permeability of compacted specimens of asphalt rubber concrete are measured and compared to their normal and random incidence sound absorption coefficients as a function of crumb rubber content in the modified binder. Nonlinear trends are found between the sound absorption coefficients, porosity and absolute permeability of the compacted specimens and the percentage of crumb rubber in the modified binders. The cross-sectional areas of the air voids on the surfaces of the compacted specimens are measured using digital image processing techniques and a linear relationship is obtained between the average void area and crumb rubber content. The measured material properties are used to construct an empirical formula relating the average porosity, normal incidence noise reduction coefficients and

Grand Canyon riverbed sediment changes, experimental release of September 2000 - a sample data set

USGS Publications Warehouse

Wong, Florence L.; Anima, Roberto J.; Galanis, Peter; Codianne, Jennifer; Xia, Yu; Bucciarelli, Randy; Hamer, Michael

2003-01-01

An experimental water release from the Glen Canyon Dam into the Colorado River above Grand Canyon was conducted in September 2000 by the U.S. Bureau of Reclamation. The U.S. Geological Survey (USGS) conducted sidescan sonar surveys between Glen Canyon Dam (mile -15) and Diamond Creek (mile 220), Arizona (mile designations after Stevens, 1998) to determine the sediment characteristics of the Colorado River bed before and after the release. The first survey (R3-00-GC, 28 Aug to 5 Sep 2000) was conducted before the release when the river was at its Low Summer Steady Flow (LSSF) of 8,000 cfs. The second survey (R4-00-GC, 10 to 18 Sep 2000) was conducted immediately after the September 2000 experimental release when the average daily flow was as high as 30,800 cfs as measured below Glen Canyon Dam (Figure 2). Riverbed sediment properties interpreted from the sidescan sonar images include sediment type and sandwaves; overall changes in these properties between the two surveys were calculated. Sidescan sonar data from the USGS surveys were processed for segments of the Colorado River from Glen Canyon Dam (mile -15) to Phantom Ranch (mile 87.7, Figure 3). The surveys targeted pools between rapids that are part of the Grand Canyon Monitoring and Research Center (GCMRC http://www.gcmrc.gov/) physical sciences study. Maps interpreted from the sidescan sonar images show the distribution of sediment types (bedrock, boulders, pebbles or cobbles, and sand) and the extent of sandwaves for each of the pre- and post-flow surveys. The changes between the two surveys were calculated with spatial arithmetric and had properties of fining, coarsening, erosion, deposition, and the appearance or disappearance of sandwaves.

Sand pulses and sand patches on the Colorado River in Grand Canyon

USGS Publications Warehouse

Grams, Paul E.; Buscombe, Daniel; Topping, David; Mueller, Erich R.

2017-01-01

Alluvial sandbars occur in lateral recirculation zones (eddies) along the Colorado River in Grand Canyon National Park (Schmidt, 1990). Resource managers periodically release controlled floods from the upstream Glen Canyon Dam to rebuild these bars (Grams et al., 2015), which erode during fluctuating dam releases, and by hillslope runoff and wind deflation (Hazel et al., 2010). Because the dam blocks upstream sediment, episodic floods from tributaries provide the only supply to replace eroded sand; and much of this sand originates from a single tributary (Topping et al., 2000). Here, we present new evidence for the downstream translation of the sand component of these sediment inputs as discontinuous sand pulses. Improved understanding of the behaviour of these sand pulses may be used to adjust the timing, magnitude, and duration of controlled floods to maximize potential for deposition on sandbars in different segments of the 450 km-long Grand Canyon.

Colorado River campsite monitoring, Grand Canyon National Park, Arizona, 1998-2012

USGS Publications Warehouse

Kaplinski, Matt; Hazel, Joe; Parnell, Rod; Hadley, Daniel R.; Grams, Paul

2014-01-01

River rafting trips and hikers use sandbars along the Colorado River in Marble and Grand Canyons as campsites. The U.S. Geological Survey evaluated the effects of Glen Canyon Dam operations on campsite areas on sandbars along the Colorado River in Grand Canyon National Park. Campsite area was measured annually from 1998 to 2012 at 37 study sites between Lees Ferry and Diamond Creek, Arizona. The primary purpose of this report is to present the methods and results of the project. Campsite area surveys were conducted using total station survey methods to outline the perimeter of camping area at each study site. Campsite area is defined as any region of smooth substrate (most commonly sand) with no more than an 8 degree slope and little or no vegetation. We used this definition, but relaxed the slope criteria to include steeper areas near boat mooring locations where campers typically establish their kitchens. The results show that campsite area decreased over the course of the study period, but at a rate that varied by elevation zone and by survey period. Time-series plots show that from 1998 to 2012, high stage-elevation (greater than the 25,000 ft3/s stage-elevation) campsite area decreased significantly, although there was no significant trend in low stage-elevation (15,000–20,000 ft3/s) campsite area. High stage-elevation campsite area increased after the 2004 and 2008 high flows, but decreased in the intervals between high flows. Although no overall trend was detected for low stage-elevation campsite areas, they did increase after high-volume dam releases equal to or greater than about 20,000 ft3/s. We conclude that dam operations have not met the management objectives of the Glen Canyon Adaptive Management program to increase the size of camping beaches in critical and non-critical reaches of the Colorado River between Glen Canyon Dam and Lake Mead.

Effects of Building‒roof Cooling on Flow and Distribution of Reactive Pollutants in street canyons

NASA Astrophysics Data System (ADS)

Park, S. J.; Choi, W.; Kim, J.; Jeong, J. H.

2016-12-01

The effects of building‒roof cooling on flow and dispersion of reactive pollutants were investigated in the framework of flow dynamics and chemistry using a coupled CFD‒chemistry model. For this, flow characteristics were analyzed first in street canyons in the presence of building‒roof cooling. A portal vortex was generated in street canyon, producing dominant reverse and outward flows near the ground in all the cases. The building‒roof cooling increased horizontal wind speeds at the building roof and strengthened the downward motion near the downwind building in the street canyon, resultantly intensifying street canyon vortex strength. The flow affected the distribution of primary and secondary pollutants. Concentrations of primary pollutants such as NOx, VOC and CO was high near the upwind building because the reverse flows were dominant at street level, making this area the downwind region of emission sources. Concentration of secondary pollutant such as O3 was lower than the background near the ground, where NOX concentrations were high. Building‒roof cooling decreased the concentration of primary pollutants in contrasted to those under non‒cooling conditions. In contrast, building‒roof cooling increased O3 by reducing NO concentrations in urban street canyon compared to concentrations under non‒cooling conditions.

Direct sampling during multiple sediment density flows reveals dynamic sediment transport and depositional environment in Monterey submarine canyon

NASA Astrophysics Data System (ADS)

Maier, K. L.; Gales, J. A.; Paull, C. K.; Gwiazda, R.; Rosenberger, K. J.; McGann, M.; Lundsten, E. M.; Anderson, K.; Talling, P.; Xu, J.; Parsons, D. R.; Barry, J.; Simmons, S.; Clare, M. A.; Carvajal, C.; Wolfson-Schwehr, M.; Sumner, E.; Cartigny, M.

2017-12-01

Sediment density flows were directly sampled with a coupled sediment trap-ADCP-instrument mooring array to evaluate the character and frequency of turbidity current events through Monterey Canyon, offshore California. This novel experiment aimed to provide links between globally significant sediment density flow processes and their resulting deposits. Eight to ten Anderson sediment traps were repeatedly deployed at 10 to 300 meters above the seafloor on six moorings anchored at 290 to 1850 meters water depth in the Monterey Canyon axial channel during 6-month deployments (October 2015 - April 2017). Anderson sediment traps include a funnel and intervalometer (discs released at set time intervals) above a meter-long tube, which preserves fine-scale stratigraphy and chronology. Photographs, multi-sensor logs, CT scans, and grain size analyses reveal layers from multiple sediment density flow events that carried sediment ranging from fine sand to granules. More sediment accumulation from sediment density flows, and from between flows, occurred in the upper canyon ( 300 - 800 m water depth) compared to the lower canyon ( 1300 - 1850 m water depth). Sediment accumulated in the traps during sediment density flows is sandy and becomes finer down-canyon. In the lower canyon where sediment directly sampled from density flows are clearly distinguished within the trap tubes, sands have sharp basal contacts, normal grading, and muddy tops that exhibit late-stage pulses. In at least two of the sediment density flows, the simultaneous low velocity and high backscatter measured by the ADCPs suggest that the trap only captured the collapsing end of a sediment density flow event. In the upper canyon, accumulation between sediment density flow events is twice as fast compared to the lower canyon; it is characterized by sub-cm-scale layers in muddy sediment that appear to have accumulated with daily to sub-daily frequency, likely related to known internal tidal dynamics also measured

Effects of Wildfire on the Hydrology of Capulin and Rito de los Frijoles canyons, Bandelier National Monument, New Mexico

USGS Publications Warehouse

Veenhuis, Jack E.

2002-01-01

In June of 1977, the La Mesa wildfire burned 15,270 acres in and around Frijoles Canyon in Bandelier National Monument and the adjacent Santa Fe National Forest, New Mexico. The Dome wildfire in April of 1996 in Bandelier National Monument burned 16,516 acres in Capulin Canyon and the surrounding Dome Wilderness area. Both watersheds are characterized by abundant and extensive archeological sites that could be affected by increased runoff and accelerated rates of erosion, which typically occur after a wildfire. The U.S. Geological Survey in cooperation with the National Park Service monitored the wildfires' effects on streamflow in both canyons. The magnitude of large stormflows increased dramatically after these wildfires; peak flows at the most downstream streamflow-gaging station in Frijoles and Capulin Canyons increased to about 160 times the maximum recorded flood prior to the fire. Maximum peak flow was 3,030 cubic feet per second at the gaging station in Frijoles Canyon (drainage area equals 18.1 square miles) and 3,630 cubic feet per second at the most downstream crest-stage gage in Capulin Canyon (drainage area equals 14.1 square miles). The pre-fire maximum peak flow recorded in these two canyons was 19 and an estimated 25 cubic feet per second, respectively. As vegetation reestablished itself during the second year, the post-fire annual maximum peak flow decreased to about 10 to 15 times the pre-fire annual maximum peak flow. During the third year, maximum annual peak flows decreased to about three to five times the pre-fire maximum peak flow. In the 22 years since the La Mesa wildfire, flood magnitudes have not completely returned to pre-fire size. Post-fire flood magnitudes in Frijoles and Capulin Canyons do not exceed the maximum floods per drainage area for physiographic regions 5 and 6 in New Mexico. For a burned watershed, however, the peak flows that occur after a wildfire are several orders of magnitude larger than normal forested watershed peak

A Numerical Study on Characteristics of Flow and Reactive Pollutant Dispersion in Step‒up Street Canyons

NASA Astrophysics Data System (ADS)

Kim, E. R.; Kim, J.

2014-12-01

For decades, many metro‒ and/or mega‒cities have grown and densities of population and building have increased. Because pollutants released from sources near ground surface such as vehicles are not easy to escape from street canyons which are spaces between buildings standing along streets pedestrians, drivers and residents are likely to be exposed to high concentrations of hazardous pollutants. Therefore, it is important to understand characteristics of flow and pollutant dispersion in street canyons. In this study, step‒up street canyons with higher downwind buildings are considered for understanding flow and reactive pollutants' dispersion characteristics there as a basic step to understand the characteristics in wider urban areas. This study used a CFD model coupled to a chemistry module. Detailed flow and air pollutant concentration are analyzed in step‒up street canyons with different upwind building heights.

Origin, transport and burial of organic matter in the Whittard Canyon, North East Atlantic

NASA Astrophysics Data System (ADS)

Kershaw, C. E.

2016-02-01

Submarine canyons, large and complex topographic features commonly found at all continental margins, are usually considered efficient conduits of material to the deep sea that can also harbour varied and well developed ecosystems. Recent work from canyons of the Portuguese margin have revealed a highly heterogeneous environment home to diverse habitats, highlighting the significance of submarine canyons and the need for a more comprehensive understanding of the processes within them. Submarine environments are influenced by the variability of the oceanographic and biogeochemical regimes and the interaction with complex topography. The purpose of this research is to examine the provenance, transportation, burial potential and ecological function of sedimentary organic matter at targeted sites of the Whittard submarine canyon (Celtic Sea, North East Atlantic), one of the largest ( 100 km across, down to 4500 m depth) most complex topographic features in the North Western European Margin, and home to an array of diverse benthic ecosystems. Sediment cores down to 50 cm were collected during three surveys in 2013, 2014 and 2015 at various depths across different channels and sedimentological and biogeochemical analyses have begun. Preliminary results have provided a glimpse of the distinct energy regime of the different canyon channels and differing carbon concentrations, emphasizing the complexity of the system. The project aims to elucidate the significance of the Whittard system in marine biogeochemical cycling and deep-sea ecosystem functioning, through further mineralogical and chemical characterization.

Relationship between rooftop and on-road concentrations of traffic-related pollutants in a busy street canyon: Ambient wind effects.

PubMed

Kwak, Kyung-Hwan; Lee, Sang-Hyun; Seo, Jaemyeong Mango; Park, Seung-Bu; Baik, Jong-Jin

2016-01-01

Rooftop and on-road measurements of O3, NO2, NOx, and CO concentrations were conducted to investigate the relationship between rooftop and on-road concentrations in a busy and shallow street canyon with an aspect ratio of ∼0.3 in Seoul, Republic of Korea, from 15 April to 1 May 2014. The median road-to-roof concentration ratios, correlation coefficients between rooftop and on-road concentrations, and temporal variations of rooftop and on-road concentrations are analyzed according to the rooftop wind directions which are two cross-canyon and two along-canyon directions. The analysis results indicate that the relationship is strong when the rooftop is situated on the downwind side rather than on the upwind side. Relative to the cross-canyon wind directions, one of the along-canyon wind directions can more enhance the relationship. A conceptual framework is proposed to explain the effect of ambient wind direction on the relationship between rooftop and on-road concentrations in a street canyon. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hydrology of the U.S. Army Pinon Canyon maneuver site, Las Animas County, Colorado

USGS Publications Warehouse

Von Guerard, Paul; Abbott, P.O.; Nickless, Raymond C.

1987-01-01

The U.S. Department of the Army (Fort Carson Military Reservation) has acquired 381 sq mi of semiarid rangeland in southeastern Colorado for mechanized military maneuvers. The study area, known as the Pinon Canyon Maneuver Site, drains into the Purgatoire River, a major tributary of the upper Arkansas River. A multidisciplined hydrologic investigation began in October 1982. The primary aquifer in the Maneuver Site is the Dakota-Purgatoire. Well yields generally range from 10 to 500 gal/min. Dissolved solids concentrations in groundwater ranged from 195 to 6,150 mg/L. Streamflow in the Purgatoire River is perennial. Tributaries draining the Maneuver Site are intermittent or ephemeral and contribute only about 4.4% of the streamflow of the Purgatoire River downstream from the Maneuver Site. Flood frequencies were calculated by using the log Pearson III procedure and compared well with a regional estimating technique that was developed that uses physical drainage-basin characteristics. Calcium and sulfate are the predominant ions in the surface water of the area. Time-series plots indicate that instream water-quality standards for nitrate and metals are exceeded. About 80% of the suspended-sediment load is transported by rainfall runoff, which occurs less than 8% of the time. Ephermal tributaries contributed less than 25% of the suspended-sediment load transported to the Purgatoire River downstream from the Maneuver Site. Historic annual mean sediment yields were measured for 29 small watersheds. Sediment yields were measured for 29 small watersheds. Sediment yields ranged from 9.5 to 1,700 tons/sq mi. Sediment yields were estimated by a multiple-linear-regression model developed by using physical drainage-basin characteristics and by the Pacific Southwest Interagency Committee method. (USGS)

The Shape of Trail Canyon Alluvial Fan, Death Valley

NASA Technical Reports Server (NTRS)

Farr, Tom G.; Dohrenwend, John C.

1993-01-01

A modified conic equation has been fit to high-resolution digital topographic data for Trail Canyon alluvial fan in Death Valley, California. Fits were accomplished for 3 individual fan units of different age.

Bridge 231, view looking east at tunnel 5 in Rock ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Bridge 23-1, view looking east at tunnel 5 in Rock Creek Canyon at Milepost 23.1 - Camas Prairie Railroad, Second Subdivision, From Spalding in Nez Perce County, through Lewis County, to Grangeville in Idaho County, Spalding, Nez Perce County, ID

Hudson Canyon Offshore New York and New Jersey: Active Circular Depressions, Fans, Ravines, Methane Discharge and Water Masses

NASA Astrophysics Data System (ADS)

Rona, P. A.; Guida, V.; Scranton, M. I.; Gong, D.; Haag, S.; Macelloni, L.; Simonetti, A.; James, J.; Diercks, A.; Asper, V. L.

2009-12-01

We investigated Hudson Canyon from where it begins at the seaward edge of the continental shelf (water depth 100 m) to ~30 km seaward (100-700 m) using high-resolution bathymetry (AUV Eagle Ray; ISE Explorer; EM2000 sonar) and standard oceanographic methods. We find features and processes that create varied distinctive habitats in submarine canyons on passive continental margins, as follows: 1)Sediment conduit: The initial 10 km- long section of the canyon head connects with cross-shelf sediment transport and is smoothed by sediment accumulation indicating that it is presently inactive as a sediment conduit, in contrast to its active role during prior intervals of lowered sea level. 2)Circular depressions: A population of circular depressions with diameters from 50 to 400 m, rim-to-floor relief up to 20 m increasing directly with diameter, flat rough floors and steep walls (15-25 degrees) occur in sediment near the base of both walls of the canyon. The number of circular depressions increases with water depth with one at 325 m in the initial 10 km-long NW-SE section of the canyon, two at 350 m in the next 10 km N-S section, and nineteen at 300 to 500 m at the SW wall of the next 10 km NW-SE section. The sharp shape of the depressions suggests that they are actively forming. Larger circular depressions (diameter <800 m) exhibit different characteristics. 3)Methane chemistry: A methane anomaly (50 nmol) ten times background was measured in August 2008 in the near-bottom water column adjacent to one of the two circular depressions in the middle canyon section. In August 2009 water samples were recovered at other circular depressions and are being analyzed to test for methane discharge. We suggest that the circular depressions are gas release-collapse features possibly produced by dissociation of underlying gas hydrates. 4)Fans and ravines: Sediment fans with intervening ravines about 1 km apart extend orthogonal to the canyon axis down the two walls of the canyon in

Benthic foraminiferal response to sedimentary disturbance in the Capbreton canyon (Bay of Biscay, NE Atlantic)

NASA Astrophysics Data System (ADS)

Duros, P.; Silva Jacinto, R.; Dennielou, B.; Schmidt, S.; Martinez Lamas, R.; Gautier, E.; Roubi, A.; Gayet, N.

2017-02-01

Living (Rose Bengal stained) and dead benthic foraminifera were investigated at 6 deep-sea sites sampled in the Capbreton canyon area (Bay of Biscay, France). Three sites were located along the canyon axis at 301 m, 983 m and 1478 m and 3 stations were positioned on adjacent terraces at 251 m, 894 m and 1454 m. Sedimentary features indicate that frequent sedimentary disturbances of different magnitudes occur along the Capbreton canyon axis and adjacent terraces. Such environmental conditions cause the presence of very particular benthic environments. Along the 6 studied sites, different foraminiferal responses to various sedimentary patterns are observed revealing the complexity of this canyon environment. Some sites (Gitan 3 (canyon axis), Gitan 5 (canyon axis) and Gitan 6 (terrace)) are characterized by moderate to low standing stocks and low diversity and are mainly dominated by pioneer taxa such as Fursenkoina brady, Reophax dentaliniformis and Technitella melo suggesting a recent response to turbidite deposits recorded at these sites. Others sites (Gitan 1 and Gitan 2) show extremely high standing stocks and are mainly dominated by the opportunistic Bolivina subaenariensis and Bulimina marginata. Such faunal characteristics belonging to a more advanced stage of ecosystem colonization indicates strongly food-enriched sediment but extremely unstable conditions. Moderate standing stocks and diverse assemblage composed of species such as Uvigerina mediterranea and U. peregrina has only been observed at the terrace site Gitan 4. More stable sedimentary conditions recorded at this terrace seem to be suitable to the development of a dense and diverse foraminiferal community. Numerous neritic allochtonous species were observed in the dead foraminiferal fauna. These allochthonous species mainly originate from shelf areas (<60 m).

Living and dead foraminiferal assemblages from an active submarine canyon and surrounding sectors: the Gioia Canyon system (Tyrrhenian Sea, Southern Italy)

NASA Astrophysics Data System (ADS)

Letizia, Di Bella; Martina, Pierdomenico; Roberta, Porretta; Chiocci, Francesco Latino; Eleonora, Martorelli

2017-05-01

Living (rose Bengal stained) and dead benthic foraminiferal assemblages were studied from 23 stations located between 60 and 670 m depth along the Gioia Canyon and the adjacent continental shelf and slope (Southern Tyrrhenian Sea). The aim of this study is to investigate the relationships among sedimentary processes, hydrological patterns and benthic foraminiferal distribution, in a highly dynamic environment. High sedimentation rates on the shelf and occasional turbidity flows along the canyon, lead to unstable environmental conditions at the seafloor that reflect on the microbenthic community influencing faunal density, diversity, species composition and distribution inside the sediment. The foraminiferal distribution seems to be controlled by sedimentary processes, nutrient supply and organic matter recycling, which in turn are strongly controlled by the seasonal variability of riverine inputs and current dynamics in the Gulf of Gioia. From the inner shelf to the upper continental slope (550 m depth), the living foraminiferal assemblage is dominated by agglutinated taxa, likely favored by the high terrigenous supply. Frequent eutrophic taxa (Valvulineria bradyana and Nonionella turgida) tolerant high turbidity (Leptohalysis scottii,) and low oxygen (Bolivina spp. and Bulimina spp.) are recorded on the edge of the inner shelf, where channeling, deposition of coastal deposits and occasional sediment gravity flows occur. In the outer sector of the shelf a turnover of species is observed; L. scottii replaced by the opportunistic species Reophax scorpiurus, and taxa indicative of high energy conditions (Cassidulina spp.) become dominant in association with mesotrophic species like Globocassidulina subglobosa. Along the continental slope, lower sedimentation rates and more stable environmental conditions support richer and more diversified foraminiferal assemblage. The abundance of Bulimina marginata indicates eutrophic conditions at the shallower station (300 m depth

Wind-dependent beluga whale dive behavior in Barrow Canyon, Alaska

NASA Astrophysics Data System (ADS)

Stafford, K. M.; Citta, J. J.; Okkonen, S. R.; Suydam, R. S.

2016-12-01

Beluga whales (Delphinapterus leucas) are the most abundant cetacean in the Arctic. The Barrow Canyon region, Alaska, is a hotspot for Pacific Arctic belugas, likely because the oceanographic environment provides reliable foraging opportunities. Fronts are known to promote the concentration of planktonic prey; when Barrow-area winds are weak or from the west, a front associated with the Alaskan Coastal Current (ACC) intensifies. This front is weakened or disrupted when strong easterly winds slow or displace the ACC. To determine if winds influence the diving depth of belugas, we used generalized linear mixed models (GLMM) to examine how the dive behavior of animals instrumented with satellite-linked time-depth recorders varied with wind conditions. When projected along-canyon winds are from the WSW and the front associated with the ACC is enhanced, belugas tend to target shallower depths (10-100 m) associated with the front. In contrast, when strong winds from the ENE displaced the ACC, belugas tended to spend more time at depths >200 m where the Arctic halocline grades into relatively warmer Atlantic Water (AW). The probability of diving to >200 m, the number of dives >200 m, and the amount of time spent below 200 m were all significantly related to along-canyon wind stress (p<0.01). From these results and known relationships between wind stress, currents and frontal structure in Barrow Canyon and the characteristic vertical distribution of Arctic cod, we infer that the probability of belugas targeting different depth regimes is based upon how wind stress affects the relative foraging opportunities between these depth regimes. Belugas are known to target AW throughout the Beaufort Sea; however, this is the first work to show that the probability of targeting the AW layer is related to wind stress.

Canyon Creek: A late Pleistocene vertebrate locality in interior Alaska

NASA Astrophysics Data System (ADS)

Weber, Florence R.; Hamilton, Thomas D.; Hopkins, David M.; Repenning, Charles A.; Haas, Herbert

1981-09-01

The Canyon Creek vertebrate-fossil locality is an extensive road cut near Fairbanks that exposes sediments that range in age from early Wisconsin to late Holocene. Tanana River gravel at the base of the section evidently formed during the Delta Glaciation of the north-central Alaska Range. Younger layers and lenses of fluvial sand are interbedded with arkosic gravel from Canyon Creek that contains tephra as well as fossil bones of an interstadial fauna about 40,000 years old. Solifluction deposits containing ventifacts, wedge casts, and rodent burrows formed during a subsequent period of periglacial activity that took place during the maximum phase of Donnelly Glaciation about 25,000-17,000 years ago. Overlying sheets of eolian sand are separated by a 9500-year-old paleosol that may correlate with a phase of early Holocene spruce expansion through central Alaska. The Pleistocene fauna from Canyon Creek consists of rodents (indicated by burrows), Mammuthus primigenius (woolly mammoth), Equus lambei (Yukon wild ass), Camelops hesternus (western camel), Bison sp. cf. B. crassicornis (large-horned bison), Ovis sp. cf. O. dalli (mountain sheep), Canis sp. cf. C. lupus (wolf), Lepus sp. cf. L. othus or L. arcticus (tundra hare), and Rangifer sp. (caribou). This assemblage suggests an open landscape in which trees and tall shrubs were either absent or confined to sheltered and moist sites. Camelops evidently was present in eastern Beringia during the middle Wisconsin interstadial interval but may have disappeared during the following glacial episode. The stratigraphic section at Canyon Creek appears to demonstrate that the Delta Glaciation of the north-central Alaska Range is at least in part of early Wisconsin age and was separated from the succeeding Donnelly Glaciation by an interstadial rather than interglacial episode.

Canyon Creek: A late Pleistocene vertebrate locality in interior Alaska

USGS Publications Warehouse

Weber, F.R.; Hamilton, T.D.; Hopkins, D.M.; Repenning, C.A.; Haas, H.

1981-01-01

The Canyon Creek vertebrate-fossil locality is an extensive road cut near Fairbanks that exposes sediments that range in age from early Wisconsin to late Holocene. Tanana River gravel at the base of the section evidently formed during the Delta Glaciation of the north-central Alaska Range. Younger layers and lenses of fluvial sand are interbedded with arkosic gravel from Canyon Creek that contains tephra as well as fossil bones of an interstadial fauna about 40,000 years old. Solifluction deposits containing ventifacts, wedge casts, and rodent burrows formed during a subsequent period of periglacial activity that took place during the maximum phase of Donnelly Glaciation about 25,000-17,000 years ago. Overlying sheets of eolian sand are separated by a 9500-year-old paleosol that may correlate with a phase of early Holocene spruce expansion through central Alaska. The Pleistocene fauna from Canyon Creek consists of rodents (indicated by burrows), Mammuthus primigenius (woolly mammoth), Equus lambei (Yukon wild ass), Camelops hesternus (western camel), Bison sp. cf. B. crassicornis (large-horned bison), Ovis sp. cf. O. dalli (mountain sheep), Canis sp. cf. C. lupus (wolf), Lepus sp. cf. L. othus or L. arcticus (tundra hare), and Rangifer sp. (caribou). This assemblage suggests an open landscape in which trees and tall shrubs were either absent or confined to sheltered and moist sites. Camelops evidently was present in eastern Beringia during the middle Wisconsin interstadial interval but may have disappeared during the following glacial episode. The stratigraphic section at Canyon Creek appears to demonstrate that the Delta Glaciation of the north-central Alaska Range is at least in part of early Wisconsin age and was separated from the succeeding Donnelly Glaciation by an interstadial rather than interglacial episode. ?? 1981.

Water chemistry of surface waters affected by the Fourmile Canyon wildfire, Colorado, 2010-2011

USGS Publications Warehouse

McCleskey, R. Blaine; Writer, Jeffrey H.; Murphy, Sheila F.

2012-01-01

In September 2010, the Fourmile Canyon fire burned about 23 percent of the Fourmile Creek watershed in Boulder County, Colo. Water-quality sampling of Fourmile Creek began within a month after the wildfire to assess its effects on surface-water chemistry. Water samples were collected from five sites along Fourmile Creek (above, within, and below the burned area) monthly during base flow, twice weekly during snowmelt runoff, and at higher frequencies during storm events. Stream discharge was also monitored. Water-quality samples were collected less frequently from an additional 6 sites on Fourmile Creek, from 11 tributaries or other inputs, and from 3 sites along Boulder Creek. The pH, electrical conductivity, temperature, specific ultraviolet absorbance, total suspended solids, and concentrations (dissolved and total) of major cations (calcium, magnesium, sodium, and potassium), anions (chloride, sulfate, alkalinity, fluoride, and bromide), nutrients (nitrate, ammonium, and phosphorus), trace metals (aluminum, arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, iron, mercury, lithium, manganese, molybdenum, nickel, lead, rubidium, antimony, selenium, strontium, vanadium, and zinc), and dissolved organic carbon are here reported for 436 samples collected during 2010 and 2011.

Beryl-bearing pegmatites in the Ruby Mountains and other areas in Nevada and northwestern Arizona

USGS Publications Warehouse

Olson, Jerry C.; Hinrichs, E. Neal

1960-01-01

Pegmatite occurs widely in Nevada and northwestern Arizona, but little mining has been done for such pegmatite minerals as mica, feldspar, beryl, and lepidolite. Reconnaissance for beryl-bearing pegmatite in Nevada and in part of Mohave County, Ariz., and detailed studies in the Dawley Canyon area, Elko County, Nev., have shown that beryl occurs in at least 11 districts in the region. Muscovite has been prospected or mined in the Ruby and Virgin Mountains, Nev., and in Mohave County, Ariz. Feldspar has been mined in the southern part of the region near Kingman, Ariz., and in Clark County, Nev. The pegmatites in the region range in age from Precambrian to late Mesozoic or Tertiary. Among the pegmatite minerals found or reported in the districts studied are beryl, chrysoberyl, scheelite, wolframite, garnet, tourmaline, fluorite, apatite, sphene, allanite, samarskite, euxenite, gadolinite, monazite, autunite, columbite-tantalite, lepidolite, molybdenite, and pyrite and other sulflde minerals. The principal beryl-bearing pegmatites examined are in the Oreana and Lakeview (Humboldt Canyon) areas, Pershing County; the Dawley Canyon area in the Ruby Mountains, Elko County, Nev.; and on the Hummingbird claims in the Virgin Mountains, Mohave County, Ariz. Beryl has also been reported in the Marietta district, Mineral County; the Sylvania district, Esmeralda County; near Crescent Peak and near Searchlight, Clark County, Nev.; and in the Painted Desert near Hoover Dam, Mohave County, Ariz. Pegmatites are abundant in the Ruby Mountains, chiefly north of the granite stock at Harrison Pass. In the Dawley Canyon area of 2.6 square miles at least 350 pegmatite dikes more than 1 foot thick were mapped, and beryl was found in small quantities in at least 100 of these dikes. Four of these dikes exceed 20 feet in thickness, and 1 is 55 feet thick. A few pegmatites were also examined in the Corral Creek, Gilbert Canyon, and Hankins Canyon areas in the Ruby Mountains.The pegmatite dikes

Capability to Recover Plutonium-238 in H-Canyon/HB-Line - 13248

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fuller, Kenneth S. Jr.; Smith, Robert H. Jr.; Goergen, Charles R.

2013-07-01

Plutonium-238 is used in Radioisotope Thermoelectric Generators (RTGs) to generate electrical power and in Radioisotope Heater Units (RHUs) to produce heat for electronics and environmental control for deep space missions. The domestic supply of Pu-238 consists of scrap material from previous mission production or material purchased from Russia. Currently, the United States has no significant production scale operational capability to produce and separate new Pu-238 from irradiated neptunium-237 targets. The Department of Energy - Nuclear Energy is currently evaluating and developing plans to reconstitute the United States capability to produce Pu-238 from irradiated Np-237 targets. The Savannah River Site hadmore » previously produced and/or processed all the Pu-238 utilized in Radioisotope Thermoelectric Generators (RTGs) for deep space missions up to and including the majority of the plutonium for the Cassini Mission. The previous full production cycle capabilities included: Np- 237 target fabrication, target irradiation, target dissolution and Np-237 and Pu-238 separation and purification, conversion of Np-237 and Pu-238 to oxide, scrap recovery, and Pu-238 encapsulation. The capability and equipment still exist and could be revitalized or put back into service to recover and purify Pu-238/Np-237 or broken General Purpose Heat Source (GPHS) pellets utilizing existing process equipment in HB-Line Scrap Recovery, and H-Canyon Frame Waste Recovery processes. The conversion of Np-237 and Pu-238 to oxide can be performed in the existing HB-Line Phase-2 and Phase- 3 Processes. Dissolution of irradiated Np-237 target material, and separation and purification of Np-237 and Pu-238 product streams would be possible at production rates of ∼2 kg/month of Pu-238 if the existing H-Canyon Frames Process spare equipment were re-installed. Previously, the primary H-Canyon Frames equipment was removed to be replaced: however, the replacement project was stopped. The spare

Characterising the pollutant ventilation characteristics of street canyons using the tracer age and age spectrum

NASA Astrophysics Data System (ADS)

Lo, K. W.; Ngan, K.

2015-12-01

The age of air, which measures the time elapsed between the emission of a chemical constituent and its arrival at a receptor location, has many applications in urban air quality. Typically it has been estimated for special cases, e.g. the local mean age of air for a spatially homogeneous source. An alternative approach uses the response to a point source to determine the distribution of transit times or tracer ages connecting the source and receptor. The distribution (age spectrum) and first moment (mean tracer age) have proven to be useful diagnostics in stratospheric modelling because they can be related to observations and do not require a priori assumptions. The tracer age and age spectrum are applied to the pollutant ventilation of street canyons in this work. Using large-eddy simulations of flow over a single isolated canyon and an uneven, non-uniform canyon array, it is shown that the structure of the tracer age is dominated by the central canyon ;vortex;; small variations in the building height have a significant influence on the structure of the tracer age and the pollutant ventilation. The age spectrum is broad, with a long exponential tail whose slope depends on the canyon geometry. The mean tracer age, which roughly characterises the ventilation strength, is much greater than the local mean age of air.

Advanced oil recovery technologies for improved recovery from slope basin clastic reservoirs, Nash Draw Brushy Canyon Pool, Eddy County, NM. Second annual technical progress report, October 1, 1996--September 30, 1997

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1998-09-01

The Nash Draw Brushy Canyon Pool in Eddy County, New Mexico is a field demonstration in the US Department of Energy Class III Program. Advanced reservoir characterization techniques are being used at the Nash Draw project to develop reservoir management strategies for optimizing oil recovery from this Delaware reservoir. Analysis, interpretation, and integration of recently acquired geological, geophysical, and engineering data revealed that the initial reservoir description was too simplistic to capture the critical features of this complex formation. As a result of the analysis, a proposed pilot area was reconsidered. Comparison of seismic data and engineering data have shownmore » evidence of discontinuities in the area surrounding the proposed injector. Analysis of the 3-D seismic has shown that wells in the proposed pilot are in an area of poor quality amplitude development. The implication is that since amplitude attenuation is a function of porosity, then this is not the best area to be attempting a pilot pressure maintenance project. Because the original pilot area appears to be compartmentalized, the lateral continuity between the pilot wells could be reduced. The 3-D seismic interpretation indicates other areas may be better suited for the initial pilot area. Therefore, the current focus has shifted more to targeted drilling, and the pilot injection will be considered in a more continuous area of the NDP in the future. Results of reservoir simulation studies indicate that pressure maintenance should be started early when reservoir pressure is still high.« less

Archaeological Test and Data Recovery Program at Telegraph Canyon, Chula Vista, California,

DTIC Science & Technology

1978-09-01

Several areas in the immediate vicinity were known to contain subsurface cables used to control SDG &E’s power network, and required avoidance. Addi...3 oEST FACE A TRENCH 4 Corps of Engineers Telegraph Canyon Creek WESTEC Servjces. Inr . compass bearing 20 7 ;7777,77 .77 7 1 METERS 170 c{ METERS...666 1.00 ~ 0 1.33 E -2.*00 -2.33 2.66 3.00 FUREf TRENCH 4 Corps of EngineersgTelegraph Canyon Creek; compass bearing 20 28 ’Lb..--._ .. *.* o •- -. o

Geologic map of the South Jackson Mountains Wilderness Study Area, Humboldt County, Nevada

USGS Publications Warehouse

Sorensen, Martin L.

1986-01-01

The South Jackson Mountains Wilderness Study Area is in south-central Humboldt County, approximately 50 miles northwest of Winnemucca, Nevada. The boundaries originally specified for the wilderness study area encompassed an area of 60,211 acres. The draft Environmental Impact Statement issued in 1983 by the U.S. Bureau of Land Management (BLM) identified 20,094 acres within the wilderness study area as potentially suitable for inclusion into the National Wilderness Preservation System. Subsequent (August 27, 1984) deletions by the BLM have resulted in the present study area of approximately 10,300 acres. The boundaries of the study area are approximated by the range crestline to the east and the 4,400-ft contour along the west side of the range from King Lear Peak north to the divide between Hobo and Christiorsson Canyons.

A new model for turbidity current behavior based on integration of flow monitoring and precision coring in a submarine canyon

USGS Publications Warehouse

Symons, William O.; Sumner, Esther J.; Paull, Charles K.; Cartigny, Matthieu J.B.; Xu, Jingping; Maier, Katherine L.; Lorenson, Thomas; Talling, Peter J.

2017-01-01

Submarine turbidity currents create some of the largest sediment accumulations on Earth, yet there are few direct measurements of these flows. Instead, most of our understanding of turbidity currents results from analyzing their deposits in the sedimentary record. However, the lack of direct flow measurements means that there is considerable debate regarding how to interpret flow properties from ancient deposits. This novel study combines detailed flow monitoring with unusually precisely located cores at different heights, and multiple locations, within the Monterey submarine canyon, offshore California, USA. Dating demonstrates that the cores include the time interval that flows were monitored in the canyon, albeit individual layers cannot be tied to specific flows. There is good correlation between grain sizes collected by traps within the flow and grain sizes measured in cores from similar heights on the canyon walls. Synthesis of flow and deposit data suggests that turbidity currents sourced from the upper reaches of Monterey Canyon comprise three flow phases. Initially, a thin (38–50 m) powerful flow in the upper canyon can transport, tilt, and break the most proximal moorings and deposit chaotic sands and gravel on the canyon floor. The initially thin flow front then thickens and deposits interbedded sands and silty muds on the canyon walls as much as 62 m above the canyon floor. Finally, the flow thickens along its length, thus lofting silty mud and depositing it at greater altitudes than the previous deposits and in excess of 70 m altitude.

Draft environmental assessment: Lavender Canyon site, Utah. Nuclear Waste Policy Act (Section 112). [Contains glossary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1984-12-01

In February 1983, the US Department of Energy (DOE) identified the Lavender Canyon site in Utah, as one of nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Lavender Canyon site and the eight other potentially acceptable sites h

Geologic map of the Tuba City 30' x 60' quadrangle, Coconino County, northern Arizona

USGS Publications Warehouse

Billingsley, George H.; Stoffer, Philip W.; Priest, Susan S.

2012-01-01

The Tuba City 30’ x 60’ quadrangle encompasses approximately 5,018 km² (1,920 mi²) within Coconino County, northern Arizona. It is characterized by nearly flat lying to gently dipping sequences of Paleozoic and Mesozoic strata that overly tilted Precambrian strata or metasedimentary and igneous rocks that are exposed at the bottom of Grand Canyon. The Paleozoic rock sequences from Cambrian to Permian age are exposed in the walls of Grand Canyon, Marble Canyon, and Little Colorado River Gorge. Mesozoic sedimentary rocks are exposed in the eastern half of the quadrangle where resistant sandstone units form cliffs, escarpments, mesas, and local plateaus. A few Miocene volcanic dikes intrude Mesozoic rocks southwest, northwest, and northeast of Tuba City, and Pleistocene volcanic rocks representing the northernmost extent of the San Francisco Volcanic Field are present at the south-central edge of the quadrangle. Quaternary deposits mantle much of the Mesozoic rocks in the eastern half of the quadrangle and are sparsely scattered in the western half. Principal folds are the north-south-trending, east-dipping Echo Cliffs Monocline and the East Kaibab Monocline. The East Kaibab Monocline elevates the Kaibab, Walhalla, and Coconino Plateaus and parts of Grand Canyon. Grand Canyon erosion has exposed the Butte Fault beneath the east Kaibab Monocline, providing a window into the structural complexity of monoclines in this part of the Colorado Plateau. Rocks of Permian and Triassic age form the surface bedrock of Marble Plateau and House Rock Valley between the East Kaibab and Echo Cliffs Monoclines. The Echo Cliffs Monocline forms a structural boundary between the Marble Plateau to the west and the Kaibito and Moenkopi Plateaus to the east. Jurassic rocks of the Kaibito and Moenkopi Plateaus are largely mantled by extensive eolian sand deposits. A small part of the northeast-dipping Red Lake Monocline is present in the northeast corner of the quadrangle. A broad and

Direct Measurements of the Evolution and Impact of Sediment Density Flows as they Pass Through Monterey Submarine Canyon, Offshore California

NASA Astrophysics Data System (ADS)

Paull, C. K.; Talling, P.; Maier, K. L.; Parsons, D. R.; Xu, J.; Caress, D. W.; Gwiazda, R.; Lundsten, E. M.; Anderson, K.; Barry, J.; Chaffey, M. R.; O'Reilly, T. C.; Rosenberger, K. J.; Gales, J. A.; McGann, M.; McCann, M. P.; Simmons, S.; Sumner, E.

2017-12-01

Sediment density flows flushing through submarine canyons carry globally significant amounts of material into the deep sea to form many of the largest sediment accumulations on Earth. Despite their global significance, these flows remain poorly understood because they have rarely been directly measured. Here we provide an initial overview of the recently completed Coordinated Canyon Experiment (CCE), which was undertaken specifically to provide detailed measurements of sediment density flows and their impact on seafloor morphology and sedimentology. No previous study has deployed as extensive an array of monitoring sensors along a turbidity current pathway. During the 18 months of the CCE, at least 15 sediment density flows were recorded within the axis of Monterey Canyon. Because no external triggers (i.e., earthquakes or floods) correlate with these flows, they must have originated as failures in the canyon floor or canyon flanks. Three flows ignited and ran out for > 50 km from water depths of <200 to >1,860 m, reaching velocities up to 8.1 m/s. The rest of the flows died out within the array. During these events, large objects on or in the canyon floor were displaced substantial distances downslope, including a 7.1 km downslope movement of an entire mooring; a 4.6 km displacement of an 860 kg instrument frame followed by repeated down canyon displacements of this same frame after it was entombed in sediment; and multiple depth changes of man-made boulders containing acceleration and pressure sensors. During this same time interval the canyon floor was mapped six times with autonomous underwater vehicles covering the canyon thalweg at the upper and lower end of the instrument array (200-540 and 1350-1880 m water depths). The repeated mapping surveys reveal that flows caused +3 to -3 m bathymetric changes within a continuous clearly defined 200 m wide swath running along the canyon axis in <200 to >540 m water depth. This study shows that sediment density flows

Measurements of velocity and discharge, Grand Canyon, Arizona, May 1994

USGS Publications Warehouse

Oberg, Kevin A.; Fisk, Gregory G.; ,

1995-01-01

The U.S. Geological Survey (USGS) evaluated the feasibility of utilizing an acoustic Doppler current profiler (ADCP) to collect velocity and discharge data in the Colorado River in Grand Canyon, Arizona, in May 1994. An ADCP is an instrument that can be used to measure water velocity and discharge from a moving boat. Measurements of velocity and discharge were made with an ADCP at 54 cross sections along the Colorado River between the Little Colorado River and Diamond Creek. Concurrent measurements of discharge with an ADCP and a Price-AA current meter were made at three U.S. Geological Survey streamflow-gaging stations: Colorado River above the Little Colorado River near Desert View, Colorado River near Grand Canyon, and Colorado River above Diamond Creek near Peach Springs. Discharges measured with an ADCP were within 3 percent of the rated discharge at each streamflow-gaging station. Discharges measured with the ADCP were within 4 percent of discharges measured with a Price-AA meter, except at the Colorado River above Diamond Creek. Vertical velocity profiles were measured with the ADCP from a stationary position at four cross sections along the Colorado River. Graphs of selected vertical velocity profiles collected in a cross section near National Canyon show considerable temporal variation among profile.

Sediment transport processes at the head of Halibut Canyon, Eastern Canada margin: An interplay between internal tides and dense shelf water cascading.

NASA Astrophysics Data System (ADS)

Puig, Pere; Greenan, Blair J. W.; Li, Michael Z.; Prescott, Robert H.; Piper, David J. W.

2013-04-01

To investigate the processes by which sediment is transported through a submarine canyon incised in a glaciated margin, the bottom boundary layer quadrapod RALPH was deployed at 276-m depth in the West Halibut Canyon (off Newfoundland) during winter 2008-2009. Two main sediment transport processes were identified throughout the deployment. Firstly, periodic increases of near-bottom suspended-sediment concentrations (SSC) were recorded associated with the up-canyon propagation of the semidiurnal internal tidal bore along the canyon axis, carrying fine sediment particles resuspended from deeper canyon regions. The recorded SSC peaks, lasting less than one hour, were observed sporadically and were linked to bottom intensified up-canyon flows concomitant with sharp drops in temperature. Secondly, sediment transport was also observed during events of intensified down-canyon current velocities that occurred during periods of sustained heat loss from surface waters, but were not associated with large storms. High-resolution velocity profiles throughout the water column during these events revealed that the highest current speeds (~1 m s-1) were centered several meters above the sea floor and corresponded to the region of maximum velocities of a gravity flow. Such flows had associated low SSC and cold water temperatures and have been interpreted as dense shelf water cascading events channelized along the canyon axis. Sediment transport during these events was largely restricted to bedload and saltation, producing winnowing of sands and fine sediments around larger gravel particles. Analysis of historical hydrographic data suggests that the origin of such gravity flows is not related to the formation of coastal dense waters advected towards the canyon head. Rather, the dense shelf waters appear to be generated around the outer shelf, where convection during winter is able to reach the sea floor and generate a pool of near-bottom dense water that cascades into the canyon

Geologic setting and genesis of the Mule Canyon low-sulfidation epithermal gold-silver deposit, north-central Nevada

USGS Publications Warehouse

John, D.A.; Hofstra, A.H.; Fleck, R.J.; Brummer, J.E.; Saderholm, E.C.

2003-01-01

The Mule Canyon mine exploited shallow, low-sulfidation, epithermal Au-Ag deposits that lie near the west side of the Northern Nevada rift in northern Lander County, Nevada. Mule Canyon consists of six small deposits that contained premining reserves of about 8.2 Mt at an average grade of 3.81 g Au/tonne. It is an uncommon mafic end member of low-sulfidation Au-Ag deposits associated with tholeiitic bimodal basalt-rhyolite magmatism. The ore is hosted by a basalt-andesite eruptive center that formed between about 16.4 to 15.8 Ma during early mafic eruptions related to regionally extensive bimodal magmatism. Hydrothermal alteration and Au-Ag ores formed at about 15.6 Ma and were tightly controlled by north-northwest- to north-striking high-angle fault and breccia zones developed during rifting, emplacement of mafic dikes, and eruption of mafic lava flows. Hydrothermal alteration assemblages are zoned outward from fluid conduits in the sequence silica-adularia, adularia-smectite, smectite (intermediate argillic), and smectite-carbonate (propylitic). All alteration types contain abundant pyrite and/or marcasite ?? arsenopyrite. Field relations indicate that silica-adularia alteration is superimposed on argillic and propylitic alteration. Little or no steam-heated acid-sulfate alteration is present, probably the result of a near-surface water table during hydrothermal alteration and ore deposition. Two distinct ore types are present at Mule Canyon: early replacement and later open-space filling. Replacement ores consist of disseminated and vesicle-filling pyrite, marcasite, and arsenopyrite in argillically altered or weakly silicified rocks. Ore minerals consist of Au-bearing arsenopyrite and arsenian pyrite overgrowths on earlier-formed pyrite and marcasite. Open-space filling ores include narrow stockwork quartz-adularia veins, banded and crustiform opaline and chalcedonic silica-adularia veins, silica-adularia cemented breccias, and sparse carbonate-pyrite and

4. VIEW OF RUINS OF FINE ORE MILL (FEATURE 20), ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. VIEW OF RUINS OF FINE ORE MILL (FEATURE 20), FACING SOUTHEAST. - Copper Canyon Camp of the International Smelting & Refining Company, Ruins of the Fine Ore Mill, Copper Canyon, Battle Mountain, Lander County, NV

3. VIEW OF STORAGE (FEATURE 24), FACING NORTH. HEADFRAME AND ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. VIEW OF STORAGE (FEATURE 24), FACING NORTH. HEADFRAME AND STORAGE TANKS (FEATURE 18) VISIBLE AT RIGHT. - Copper Canyon Camp of the International Smelting & Refining Company, Storage, Copper Canyon, Battle Mountain, Lander County, NV

Multibeam bathymetric survey of the Ipala Submarine Canyon, Jalisco, Mexico (20°N): The southern boundary of the Banderas Forearc Block?

NASA Astrophysics Data System (ADS)

Urías Espinosa, J.; Bandy, W. L.; Mortera Gutiérrez, C. A.; Núñez Cornú, Fco. J.; Mitchell, N. C.

2016-03-01

The Middle America Trench bends sharply northward at 20°N. This, along with the close proximity of the Rivera-North America Euler pole to the northern end of this trench, sharply increases the obliquity of subduction at 20°N. By analogy with other subduction zones with similar sharply changing obliquity, significant trench parallel extension is expected to exist in the forearc region near the bend. To evaluate this possibility, multibeam bathymetric, seafloor backscatter and sub-bottom seismic reflection data were collected in this area during the MORTIC08 campaign of the B.O. El Puma. These data image in detail a large submarine canyon (the Ipala Canyon) extending from the coast at 20°05‧N to the Middle America Trench at 19°50‧N. This canyon is 114 km long and is fed by sediments originating from two, possibly three, small rivers: the Ipala, Tecolotlán and Maria Garza. This canyon deeply incises (up to 600 m) the entire continental slope and at least the outer part of the shelf. Within the canyon, we observe meanders and narrow channels produced by turbidity flows indicating that the canyon is active. In the marginal areas of the canyon slumps, rills, and uplifts suggest that mass movements and fluid flow have had a major impact on the seafloor morphology. The seafloor bathymetry, backscatter images and sub-bottom reflection profiles evidence the tectonic processes occurring in this area. Of particular interest, the canyon is deflected by almost 90° at three locations, the deflections all having a similar azimuth of between 125° and 130°. Given the prominence and geometry of this canyon, along with its tectonic setting, we propose that the presence of the canyon is related to extension produced by the sharp change in the plate convergence. If so, the canyon may lie along the southeast boundary of a major forearc block (the Banderas Forearc Block).

Vertical stratification in the distribution of demersal fishes along the walls of the La Jolla and Scripps submarine canyons, California, USA

NASA Astrophysics Data System (ADS)

Smith, Joshua G.; Lindholm, James

2016-08-01

The geographic distributions of many coastal marine fish assemblages are strongly driven by habitat features, particularly among demersal fishes that live along the seafloor. Ecologists have long recognized the importance of characterizing fish habitat associations, especially where spatial management is under consideration. However, little is known about fish distributions and habitat suitability in unique demersal habitats such as submarine canyons. The active continental margin of the California coast is cut by eight submarine canyons, several of which extend from the shore to the deep abyssal plain. We sampled the demersal fish assemblages in two of those canyons: (1) the Scripps submarine canyon in the San-Diego-Scripps State Marine Conservation Area (SMCA) and (2) the La Jolla canyon in the Matlahuayl State Marine Reserve (SMR) to gain insight into both the distributions and habitat associations of demersal fishes in canyons. A remotely operated vehicle was used to conduct 21 vertically oriented transects along the canyon walls in depths ranging from 20 to 300 m. Species composition was assessed in three depth-stratified zones (100 m per zone) along the canyon walls. Species richness, abundance, and attributes of the surrounding canyon habitat structure (slope and benthic terrain ruggedness) were quantified. Three distinct assemblage groupings were identified, which comprised 35 species of demersal fishes from 17 families. Among all factors analyzed in this study, depth, slope, and ruggedness were strong explanatory variables of patterns of species richness and abundance; however, the relationship between depth and assemblage structure was non-linear. The greatest number of species was observed in the mid depth-stratified zone. These trends suggest that variation in canyon dynamics across depth strata may facilitate distinct assemblage groupings of demersal fishes, which can in turn be used to better manage these unique habitats.

75 FR 18201 - Juniper Canyon Wind Power, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-09

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER10-975-000] Juniper Canyon Wind Power, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for Blanket... of Juniper Canyon Wind Power, LLC's application for market-based rate authority, with an accompanying...

Preliminary access routes and cost study analyses for seven potentially acceptable salt sites: Final report, October 1984

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1987-02-01

This report analyzes highway and railroad access to seven potentially acceptable salt repository sites: Richton Dome and Cypress Creek Dome in Mississippi, Vacherie Dome in Louisiana, Swisher County and Deaf Smith County in Texas, and Davis Canyon and Lavender Canyon in utah. The objectives of the study were to investigate the routing of reasonable access corridors to the sites, describe major characteristics of each route, and estimate the costs for constructing or upgrading highways and railroads. The routes used in the analysis are not necessarily recommended or preferred over other routes, nor do they represent an implied final selection. Detailedmore » engineering studies must be performed for the Davis Canyon and Lavender Canyon highway access before the analyzed routes can be considered to be viable. 20 refs., 7 figs., 3 tabs.« less

Canyons and Mesas of Aureum Chaos

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 17 June 2002) This image contains a portion of Aureum Chaos located just south of the Martian equator. This fractured landscape contains canyons and mesas with two large impact craters in the upper left. The largest crater is older than the one above it. This is readily evident because a landslide deposit created by the smaller crater's impact is seen on the larger crater's floor. The overall scene has a rather muted appearance due to mantling by dust. Some small dark streaks can also be seen in this scene. These small dark streaks suggest that the materials covering this area occasionally become unstable and slide. Ridges of resistant material also can be observed in the walls of the canyons. The wall rock seen in the upper part of the cliffs appears to be layered. Classic spur and gully topography created by differing amounts of erosion and possibly different rock types is also visible here. One important observation to be made in this region is that there are no gullies apparent on the slopes such as those seen in Gorgonum Chaos (June 11th daily image). Latitude appears to play a major role in gully occurrence and distribution, with the gullies being predominately found pole ward of 30o.

Large eddy simulation of reactive pollutants in a deep urban street canyon: Coupling dynamics with O3-NOx-VOC chemistry.

PubMed

Zhong, Jian; Cai, Xiao-Ming; Bloss, William James

2017-05-01

A large eddy simulation (LES) model coupled with O 3 -NO x -VOC chemistry is implemented to simulate the coupled effects of emissions, mixing and chemical pre-processing within an idealised deep (aspect ratio = 2) urban street canyon under a weak wind condition. Reactive pollutants exhibit significant spatial variations in the presence of two vertically aligned unsteady vortices formed in the canyon. Comparison of the LES results from two chemical schemes (simple NO x -O 3 chemistry and a more comprehensive Reduced Chemical Scheme (RCS) chemical mechanism) shows that the concentrations of NO 2 and O x inside the street canyon are enhanced by approximately 30-40% via OH/HO 2 chemistry. NO, NO x , O 3 , OH and HO 2 are chemically consumed, while NO 2 and O x (total oxidant) are chemically produced within the canyon environment. Within-canyon pre-processing increases oxidant fluxes from the canyon to the overlying boundary layer, and this effect is greater for deeper street canyons (as found in many traditional European urban centres) than shallower (lower aspect ratio) streets. There is clear evidence of distinct behaviours for emitted chemical species and entrained chemical species, and positive (or negative) values of intensities of segregations are found between pairs of species with similar (or opposite) behaviour. The simplified two-box model underestimated NO and O 3 levels, but overestimated NO 2 levels for both the lower and upper canyon compared with the more realistic LES-chemistry model. This suggests that the segregation effect due to incomplete mixing reduces the chemical conversion rate of NO to NO 2 . This study reveals the impacts of nonlinear O 3 -NO x -VOC photochemical processes in the incomplete mixing environment and provides a better understanding of the pre-processing of emissions within canyons, prior to their release to the urban boundary layer, through the coupling of street canyon dynamics and chemistry. Copyright © 2017 Elsevier Ltd

Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland.

PubMed

Baynes, Edwin R C; Attal, Mikaël; Niedermann, Samuel; Kirstein, Linda A; Dugmore, Andrew J; Naylor, Mark

2015-02-24

Extreme flood events have the potential to cause catastrophic landscape change in short periods of time (10(0) to 10(3) h). However, their impacts are rarely considered in studies of long-term landscape evolution (>10(3) y), because the mechanisms of erosion during such floods are poorly constrained. Here we use topographic analysis and cosmogenic (3)He surface exposure dating of fluvially sculpted surfaces to determine the impact of extreme flood events within the Jökulsárgljúfur canyon (northeast Iceland) and to constrain the mechanisms of bedrock erosion during these events. Surface exposure ages allow identification of three periods of intense canyon cutting about 9 ka ago, 5 ka ago, and 2 ka ago during which multiple large knickpoints retreated large distances (>2 km). During these events, a threshold flow depth was exceeded, leading to the toppling and transportation of basalt lava columns. Despite continuing and comparatively large-scale (500 m(3)/s) discharge of sediment-rich glacial meltwater, there is no evidence for a transition to an abrasion-dominated erosion regime since the last erosive event because the vertical knickpoints have not diffused over time. We provide a model for the evolution of the Jökulsárgljúfur canyon through the reconstruction of the river profile and canyon morphology at different stages over the last 9 ka and highlight the dominant role played by extreme flood events in the shaping of this landscape during the Holocene.

Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland

PubMed Central

Baynes, Edwin R. C.; Attal, Mikaël; Kirstein, Linda A.; Dugmore, Andrew J.; Naylor, Mark

2015-01-01

Extreme flood events have the potential to cause catastrophic landscape change in short periods of time (100 to 103 h). However, their impacts are rarely considered in studies of long-term landscape evolution (>103 y), because the mechanisms of erosion during such floods are poorly constrained. Here we use topographic analysis and cosmogenic 3He surface exposure dating of fluvially sculpted surfaces to determine the impact of extreme flood events within the Jökulsárgljúfur canyon (northeast Iceland) and to constrain the mechanisms of bedrock erosion during these events. Surface exposure ages allow identification of three periods of intense canyon cutting about 9 ka ago, 5 ka ago, and 2 ka ago during which multiple large knickpoints retreated large distances (>2 km). During these events, a threshold flow depth was exceeded, leading to the toppling and transportation of basalt lava columns. Despite continuing and comparatively large-scale (500 m3/s) discharge of sediment-rich glacial meltwater, there is no evidence for a transition to an abrasion-dominated erosion regime since the last erosive event because the vertical knickpoints have not diffused over time. We provide a model for the evolution of the Jökulsárgljúfur canyon through the reconstruction of the river profile and canyon morphology at different stages over the last 9 ka and highlight the dominant role played by extreme flood events in the shaping of this landscape during the Holocene. PMID:25675484

Hudson Canyon benthic habitats characterization and mapping by integrated analysis of multidisciplinary data

NASA Astrophysics Data System (ADS)

Pierdomenico, Martina; Guida, Vincent G.; Rona, Peter A.; Macelloni, Leonardo; Scranton, Mary I.; Asper, Vernon; Diercks, Arne

2013-04-01

Hudson Canyon, about 180 km SE of New York City, is the largest eastern U.S. submarine canyon and is under consideration for HAPC (Habitat Area of Particular Concern) status, representing a fisheries and biodiversity hot spot. Interest in the area, within the perspective of ecosystem based management, marine spatial planning, habitat and species conservation, led to a joint project between NOAA Northeast Fisheries, U.S. Geological Survey (USGS), Mississippi Mineral Research Institute (MMRI), National Institute for Undersea Science and Technology (NIUST), Stony Brook and Rutgers Universities for the study of benthic habitats, that includes the assembly of existing data with newly collected ones: acoustic mapping, visual ground-truthing, hydrographic, sedimentological, and trawl data collections. Acoustic mapping, performed using AUV-mounted multibeam sonar, provided ultra-high resolution bathymetric and backscatter imagery (3m and 1m respectively) at all water depths for identification of geomorphological features and for the characterization of surficial sediments along the two thirds of the shelf portion of the canyon. Identification of benthic and demersal communities was accomplished by visual ground thruthing with underwater vehicle video and still cameras, and from trawl catch data. A CTD-rosette sampler provided water column salinity-temperature profiles and water samples for dissolved methane analysis in the vicinity of suspected bottom sources. Analysis of data revealed a complex of topographic structures and hydrological patterns that provide a wide range of physical habitats in a relatively small area. A mosaic of sandy and muddy substrates, gravel beds, rock outcrops, and semilithified clay outcrops host rich and varied faunal assemblages, including deepwater corals and sponge communities. Pockmark fields, occurring below 300 m depth, suggest that methane-based chemosynthetic carbonate deposition contributes to creation of specific hard bottom habitats

Study on the wind field and pollutant dispersion in street canyons using a stable numerical method.

PubMed

Xia, Ji-Yang; Leung, Dennis Y C

2005-01-01

A stable finite element method for the time dependent Navier-Stokes equations was used for studying the wind flow and pollutant dispersion within street canyons. A three-step fractional method was used to solve the velocity field and the pressure field separately from the governing equations. The Streamline Upwind Petrov-Galerkin (SUPG) method was used to get stable numerical results. Numerical oscillation was minimized and satisfactory results can be obtained for flows at high Reynolds numbers. Simulating the flow over a square cylinder within a wide range of Reynolds numbers validates the wind field model. The Strouhal numbers obtained from the numerical simulation had a good agreement with those obtained from experiment. The wind field model developed in the present study is applied to simulate more complex flow phenomena in street canyons with two different building configurations. The results indicated that the flow at rooftop of buildings might not be assumed parallel to the ground as some numerical modelers did. A counter-clockwise rotating vortex may be found in street canyons with an inflow from the left to right. In addition, increasing building height can increase velocity fluctuations in the street canyon under certain circumstances, which facilitate pollutant dispersion. At high Reynolds numbers, the flow regimes in street canyons do not change with inflow velocity.

Photocatalytic degradation of NOx in a pilot street canyon configuration using TiO2-mortar panels.

PubMed

Maggos, Th; Plassais, A; Bartzis, J G; Vasilakos, Ch; Moussiopoulos, N; Bonafous, L

2008-01-01

Titanium dioxide is the most important photocatalysts used for purifying applications. If a TiO2- containing material is left outdoors as a form of flat panels, it is activated by sunlight to remove harmful NOx gases during the day. The photocatalytic efficiency of a TiO2-treated mortar for removal of NOx was investigated in the frame of this work. For this purpose a fully equipped monitoring system was designed at a pilot site. This system allows the in situ evaluation of the de-polluting properties of a photocatalytic material by taking into account the climatologic phenomena in street canyons, accurate measurements of pollution level and full registration of meteorological data The pilot site involved three artificial canyon streets, a pollution source, continuous NOx measurements inside the canyons and the source as well as background and meteorological measurements. Significant differences on the NOx concentration level were observed between the TiO2 treated and the reference canyon. NOx values in TiO2 canyon were 36.7 to 82.0% lower than the ones observed in the reference one. Data arising from this study could be used to assess the impact of the photocatalytic material on the purification of the urban environment.

Pollutant Removal, Dispersion and Entrainment over Two-Dimensional Idealized Street Canyons: an LES Approach

NASA Astrophysics Data System (ADS)

Wong, C.; Liu, C.

2010-12-01

Unlike pollutant transport over flat terrain, the mechanism and plume dispersion over urban areas is not well known. This study is therefore conceived to examine how urban morphology modifies the pollutant transport over urban areas. The computational domain and boundary condition used in this study is shown in Figure 1. The LES shows that inside the street canyon, the ground-level pollutants are carried to roof-level by the re-circulating flow, which are then removed from the street canyon to the UBL. Right above the roof level, narrow high-speed air masses in the streamwise flows and intensive downdrafts have been found in the shear layer. Different from the flows over a smooth surface, the maximum turbulence intensities descend that are peaked near the top of the building roughness. The pollutant is rather uniformly distributed inside a street canyon but disperses rapidly over the buildings exhibiting a Gaussian-plume form in the UBL. The mean component of vertical pollutant flux shows that the mean wind contributes to pollutant removal and entrainment simultaneously. Whereas, the fluctuating component demystifies that pollutant removal is mainly governed by atmospheric turbulence. Over the roof level, atmospheric flows slow down rapidly in the wake behind leeward building, suggesting the momentum entrainment into the street canyons. The decelerating streamwise flows in turn lead to upward flows carrying pollutants away from the street canyons, illustrating the basic pollutant removal mechanism in the skimming flow regime. Figure 1: Computational domain and boundary conditions Figure 2: Ensemble average vertical pollutant flux along the roof level. (a). Mean component; (b). turbulent component.

Tectonic controls on nearshore sediment accumulation and submarine canyon morphology offshore La Jolla, Southern California

USGS Publications Warehouse

Le Dantec, Nicolas; Hogarth, Leah J.; Driscoll, Neal W.; Babcock, Jeffrey M.; Barnhardt, Walter A.; Schwab, William C.

2010-01-01

CHIRP seismic and swath bathymetry data acquired offshore La Jolla, California provide an unprecedented three-dimensional view of the La Jolla and Scripps submarine canyons. Shore-parallel patterns of tectonic deformation appear to control nearshore sediment thickness and distribution around the canyons. These shore-parallel patterns allow the impact of local tectonic deformation to be separated from the influence of eustatic sea-level fluctuations. Based on stratal geometry and acoustic character, we identify a prominent angular unconformity inferred to be the transgressive surface and three sedimentary sequences: an acoustically laminated estuarine unit deposited during early transgression, an infilling or “healing-phase” unit formed during the transgression, and an upper transparent unit. Beneath the transgressive surface, steeply dipping reflectors with several dip reversals record faulting and folding along the La Jolla margin. Scripps Canyon is located at the crest of an antiform, where the rocks are fractured and more susceptible to erosion. La Jolla Canyon is located along the northern strand of the Rose Canyon Fault Zone, which separates Cretaceous lithified rocks to the south from poorly cemented Eocene sands and gravels to the north. Isopach and structure contour maps of the three sedimentary units reveal how their thicknesses and spatial distributions relate to regional tectonic deformation. For example, the estuarine unit is predominantly deposited along the edges of the canyons in paleotopographic lows that may have been inlets along barrier beaches during the Holocene sea-level rise. The distribution of the infilling unit is controlled by pre-existing relief that records tectonic deformation and erosional processes. The thickness and distribution of the upper transparent unit are controlled by long-wavelength, tectonically induced relief on the transgressive surface and hydrodynamics.

Cold-Water Corals and Anthropogenic Impacts in La Fonera Submarine Canyon Head, Northwestern Mediterranean Sea

PubMed Central

Canals, Miquel; Ballesteros, Enric; Gili, Josep-Maria; Sanchez-Vidal, Anna

2016-01-01

We assess the occurrence and extent of cold-water coral (CWC) species Madrepora oculata and Dendrophyllia cornigera, as well as gorgonian red coral Corallium rubrum, in La Fonera canyon head (Northwestern Mediterranean Sea), as well as human impacts taking place in their habitats. Occurrence is assessed based on Remotely Operated Vehicle (ROV) video imaging. Terrain classification techniques are applied to high-resolution swath bathymetric data to obtain semi-automatic interpretative maps to identify the relationship between coral distribution patterns and canyon environments. A total of 21 ROV immersions were carried out in different canyon environments at depths ranging between 79 and 401 m. Large, healthy colonies of M. oculata occur on abrupt, protected, often overhanging, rocky sections of the canyon walls, especially in Illa Negra branch. D. cornigera is sparser and evenly distributed at depth, on relatively low sloping areas, in rocky but also partially sedimented areas. C. rubrum is most frequent between 100 and 160 m on highly sloping rocky areas. The probable extent of CWC habitats is quantified by applying a maximum entropy model to predict habitat suitability: 0.36 km2 yield M. oculata occurrence probabilities over 70%. Similar predictive models have been produced for D. cornigera and C. rubrum. All ROV transects document either the presence of litter on the seafloor or pervasive trawling marks. Nets and longlines are imaged entangled on coral colonies. Coral rubble is observed at the foot of impacted colonies. Some colonies are partially covered by sediment that could be the result of the resuspension generated by bottom trawling on neighbouring fishing grounds, which has been demonstrated to be responsible of daily increases in sediment fluxes within the canyon. The characteristics of the CWC community in La Fonera canyon are indicative that it withstands high environmental stress of both natural and human origin. PMID:27182776

A multi-approach monitoring of particulate matter, metals and PAHs in an urban street canyon.

PubMed

De Nicola, Flavia; Murena, Fabio; Costagliola, M Antonietta; Alfani, Anna; Baldantoni, Daniela; Prati, M Vittoria; Sessa, Ludovica; Spagnuolo, Valeria; Giordano, Simonetta

2013-07-01

For the first time until now, the results from a prediction model (Atmospheric Dispersion Modelling System (ADMS)-Road) of pollutant dispersion in a street canyon were compared to the results obtained from biomonitors. In particular, the instrumental monitoring of particulate matter (PM10) and the biomonitoring of 14 polycyclic aromatic hydrocarbons (PAHs) and 11 metals by Quercus ilex leaves and Hypnum cupressiforme moss bags, acting as long- and short-term accumulators, respectively, were carried out. For both PAHs and metals, similar bioaccumulation trends were observed, with higher concentrations in biomonitors exposed at the leeward canyon side, affected by primary air vortex. The major pollutant accumulation at the leeward side was also predicted by the ADMS-Road model, on the basis of the prevailing wind direction that determines different exposure of the street canyon sides to pollutants emitted by vehicular traffic. A clear vertical (3, 6 and 9 m) distribution gradient of pollutants was not observed, so that both the model and biomonitoring results suggested that local air turbulences in the street canyon could contribute to uniform pollutant distribution at different heights.

Sedimentation in Rio La Venta Canyon in Netzahualcoyotl Reservoir, Chiapas, Mexico

NASA Astrophysics Data System (ADS)

de La Fuente, J. A.; Lisle, T.; Velasquez, J.; Allison, B. L.; Miller, A.

2002-12-01

Sedimentation of Rio La Venta as it enters the Netzahualcoyotl Reservoir in Chiapas, Mexico, threatens a unique part of the aquatic ecosystem. Rio La Venta enters the reservoir via a narrow canyon about 16 km long with spectacular, near-vertical limestone bluffs up to 320 m high and inhabited by the flora and fauna of a pristine tropical forest. Karst terrain underlies most of the Rio La Venta basin in the vicinity of the reservoir, while deeply weathered granitic terrain underlies the Rio Negro basin, and the headwaters of the Rio La Venta to the south. The Rio Negro joins Rio La Venta 3 km downstream of the upper limit of the reservoir and delivers the bulk of the total clastic sediment (mostly sand and finer material). The canyon and much of the contributing basin lie within the Reserva de la Biosfera, Selva El Ocote, administered by the Comision Nacional de Areas Naturales Protegidas, part of the Secretaria de Medioambiente y Recursos Naturales. The Klamath National Forest Forest has cooperated with its Mexican counterparts since 1993 in natural resource management, neo-tropical bird inventories, wildfire management, and more recently in watershed analyses. Rates of sedimentation are estimated from bathymetric surveys conducted in March, 2002. A longitudinal profile down the inundated canyon during a high reservoir level shows an inflection from a slope of 0.0017 to one of 0.0075 at 7.2 km downstream of the mouth of Rio Negro. The bed elevation at this point corresponds to the lowest reservoir level, suggesting that the gentler sloping bed upstream is formed by fluvial processes during drawdown and that downstream by pluvial processes. Using accounts that boats could access Rio Negro during low water levels in 1984, we estimate an annual sedimentation rate of roughly 3 million cubic meters per year. This suggests that boats might no longer be able to access the most spectacular section of canyon upstream of Rio Negro within a decade, depending on how the

Modal Analysis of Two Bridges, Bryce Canyon National Park

NASA Astrophysics Data System (ADS)

Geimer, P. R.; Moore, J. R.; Thorne, M. S.; Quirk, B.

2016-12-01

We used ambient seismic data to identify the primary resonant frequencies of the up-canyon span of Two Bridges, a natural sandstone arch located in Bryce Canyon National Park, Utah. Two broadband seismometers placed on the span recorded continuous data for 14 hours, which were compared to measurements from a nearby reference station. Spectral peaks identified in the recordings represent resonant modes of the arch. We observed a slight drift in the fundamental frequency, which we attribute to daily changes in rock temperature and associated thermal stresses. However, no detectable vertical motion was recorded over the same time period using a laser distance meter. We applied slight impulses to the arch along its main axes to experimentally determine modal damping ratios, which describe the vibrational properties of the arch. Ground-based photogrammetry was then used to construct a new 3D model of the feature, which we imported into COMSOL Multiphysics to perform numerical modal analyses. By varying the material properties, we were able to match the fundamental resonant frequency of the arch and several higher order modes, as well as associated polarization attributes. Repeat resonant frequency measurements at Two Bridges will help us better understand how the structure changes over time in response to environment factors. The Claron Formation, which forms Two Bridges, is highly susceptible to weathering and erosion making natural hazards, such as rock falls, a frequent occurrence in Bryce Canyon.

Landslide assessment of Newell Creek Canyon, Oregon City, Oregon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Growney, L.; Burris, L.; Garletts, D.

1993-04-01

A study has been conducted in Newell Creek Canyon near Oregon City, Oregon, T3S, T2S, R2E. A landslide inventory has located 53 landslides in the 2.8 km[sup 2] area. The landslides range in area from approximately 15,000m[sup 2] to 10m[sup 2]. Past slides cover an approximate 7% of the canyon area. Landslide processes include: slump, slump-translational, slump-earthflow and earthflow. Hard, impermeable clay-rich layers in the Troutdale Formation form the failure planes for most of the slides. Slopes composed of Troutdale material may seem to be stable, but when cuts and fills are produced, slope failure is common because of themore » perched water tables and impermeable failure planes. Good examples of cut and fill failures are present on Highway 213 which passes through Newell Creek Canyon. Almost every cut and fill has failed since the road construction began. The latest failure is in the fill located at mile-post 2.1. From data gathered, a slope stability risk map was generated. Stability risk ratings are divided into three groups: high, moderate and low. High risk of slope instability is designated to all landslides mapped in the slide inventory. Moderate risk is designated to slopes in the Troutdale Formation greater than 8[degree]. Low risk is designated to slopes in the Troutdale Formation less than 8[degree].« less

Submarine canyons along the upper Sardinian slope (Central Western Mediterranean) as repositories for derelict fishing gears.

PubMed

Cau, Alessandro; Alvito, Andrea; Moccia, Davide; Canese, Simonepietro; Pusceddu, Antonio; Rita, Cannas; Angiolillo, Michela; Follesa, Maria C

2017-10-15

By means of ROV surveys, we assessed the quantity, composition and bathymetric distribution of marine litter in 17 sites along the Sardinian continental margin (Central Western Mediterranean) at depths ranging from 100 to 480m. None of the investigated sites was litter free, but the mean density of litter (0.0175±0.0022itemsm -2 ) was lower than that reported from other Tyrrhenian regions. The difference in the total litter density among sites was negligible, but the density of derelict fishing gear (DFG) items (most of which ascribable to small scale fishery) in submarine canyons was higher in submarine canyons than in other habitats. Our result suggest that submarine canyons (known to be highly vulnerable ecosystems) act as major repositories of DFGs, and, therefore, we anticipate the need of specific measures aimed at minimizing the loss and abandonment of DFGs in submarine canyons. Copyright © 2017 Elsevier Ltd. All rights reserved.

Three Experimental High-Flow Releases from Glen Canyon Dam, Arizona-Effects on the Downstream Colorado River Ecosystem

USGS Publications Warehouse

Melis, Theodore S.; Grams, Paul E.; Kennedy, Theodore A.; Ralston, Barbara E.; Robinson, Christopher T.; Schmidt, John C.; Schmit, Lara M.; Valdez, Richard A.; Wright, Scott A.

2011-01-01

Three high-flow experiments (HFEs) were conducted by the U.S. Department of the Interior at Glen Canyon Dam, Arizona, in March 1996, November 2004, and March 2008. Also known as artificial or controlled floods, these scheduled releases of water above the dam's powerplant capacity were designed to mimic pre-dam seasonal flooding on the Colorado River. The goal of the HFEs was to determine whether high flows could be used to benefit important downstream resources in Glen Canyon National Recreation Area and Grand Canyon National Park that have been affected by the existence and operation of Glen Canyon Dam. These downstream resources include native fish, particularly endangered humpback chub (Gila cypha), terrestrial and aquatic sandbar habitats, cultural sites, and recreational resources. This Fact Sheet summarizes HFE-related studies published since 1996 and outlines a possible strategy for implementing future HFEs.

Benthic prokaryotic community dynamics along the Ardencaple Canyon, Western Greenland Sea

NASA Astrophysics Data System (ADS)

Quéric, Nadia-Valérie; Soltwedel, Thomas

2012-07-01

The Ardencaple Canyon, emanating from the Eastern Greenland continental rise over a distance of about 200 km towards the Greenland Basin, was investigated to determine the effect of enhanced down-slope transport mechanisms on deep-sea benthic prokaryotic communities. The concentration of viable bacterial cells (Live/Dead®BacLight) and prokaryotic incorporation rates (3H-thymidine, 14C-leucine) increased with increasing distance from the continental shelf. Multidimensional scaling (MDS) results from terminal restriction fragment length polymorphism (T-RFLP) analysis indicated a spatial coherence between the benthic bacterial community structure, prokaryotic incorporation rates, water content, protein concentration and the total organic matter in the sediments. The community complexity in sediments at 4-5 cm depth was lower in the central parts of the channel compared with the northern and the southern levees, while richness in surface sediments of all stations was similar. Lacking any clear indications for a recent mass sediment transport or funneled shelf drainage flows, high similarities between bacterial assemblages in sediments along the canyon course may thus be governed by a combination of an ice-edge induced particle flux, episodic down-slope and canyon-guided transport mechanisms.

Modeled alongshore circulation and morphologic evolution onshore of a large submarine canyon

NASA Astrophysics Data System (ADS)

Hansen, J. E.; Raubenheimer, B.; List, J. H.; Elgar, S.; Guza, R. T.; Lippmann, T. C.

2012-12-01

Alongshore circulation and morphologic evolution observed at an ocean beach during the Nearshore Canyon Experiment, onshore of a large submarine canyon in San Diego, CA (USA), are investigated using a two-dimensional depth-averaged numerical model (Delft3D). The model is forced with waves observed in ~500 m water depth and tidal constituents derived from satellite altimetry. Consistent with field observations, the model indicates that refraction of waves over the canyon results in wave focusing ~500 m upcoast of the canyon and shadowing onshore of the canyon. The spatial variability in the modeled wave field results in a corresponding non-uniform alongshore circulation field. In particular, when waves approach from the northwest the alongshore flow converges near the wave focal zone, while waves that approach from the southwest result in alongshore flow that diverges away from the wave focal zone. The direction and magnitude of alongshore flows are determined by a balance between the (often opposing) radiation stress and alongshore pressure gradients, consistent with observations and previous results. The largest observed morphologic evolution, vertical accretion of about 1.5 m in about 3 m water depth near the wave focal zone, occurred over a one-week period when waves from the northwest reached heights of 1.8 m. The model, with limited tuning, replicates the magnitude and spatial extent of the observed accretion and indicates that net accretion of the cross-shore profile was owing to alongshore transport from converging alongshore flows. The good agreement between the observed and modeled morphology change allows for an in-depth examination of the alongshore force balance that resulted in the sediment convergence. These results indicate that, at least in this case, a depth-averaged hydrodynamic model can replicate observed surfzone morphologic change resulting from forcing that is strongly non-uniform in the alongshore. Funding was provided by the Office of Naval

14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

Code of Federal Regulations, 2012 CFR

2012-01-01

... Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION... TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ Pt. 93, Subpt. U, App. Appendix to Subpart U of Part 93—Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ...

14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

Code of Federal Regulations, 2010 CFR

2010-01-01

... Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION... TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ Pt. 93, Subpt. U, App. Appendix to Subpart U of Part 93—Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ...

14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

Code of Federal Regulations, 2013 CFR

2013-01-01

... Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION... TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ Pt. 93, Subpt. U, App. Appendix to Subpart U of Part 93—Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ...

14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

Code of Federal Regulations, 2011 CFR

2011-01-01

... Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION... TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ Pt. 93, Subpt. U, App. Appendix to Subpart U of Part 93—Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ...

14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

Code of Federal Regulations, 2014 CFR

2014-01-01

... Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION... TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ Pt. 93, Subpt. U, App. Appendix to Subpart U of Part 93—Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ...

Areas with Surface Thermal Anomalies as Detected by ASTER and LANDSAT Data around South Canyon Hot Springs, Garfield County, Colorado

DOE Data Explorer

Khalid Hussein

2012-02-01

This map shows areas of anomalous surface temperature around South Canyon Hot Springs as identified from ASTER and LANDSAT thermal data and spatial based insolation model. The temperature for the ASTER data was calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas having anomalous temperature in the ASTER data are shown in blue diagonal hatch, while areas having anomalous temperature in the LANDSAT data are shown in magenta on the map. Thermal springs and areas with favorable geochemistry are also shown. Springs or wells having non-favorable geochemistry are shown as blue dots.

The LACDA (Los Angeles County Drainage Area) System Recreation Study, Los Angeles County Drainage Area.

DTIC Science & Technology

1980-03-01

Channel Islands and is not conveniently situ - tions, potential benefits are greatly increased by con- ated for the daily use of large numbers of people...are at least three races of birds and some plant species on the peninsula that are found nowhere else except the Channel Islands. 32. Agua Amarga Canyon...Class 3 (4,5,7) Agua Amarga Canyon is the last remaining relatively undisturbed drainage on the coastal side of the Palos Verdes Peninsula. There

Optical characteristics of fine and coarse particulates at Grand Canyon, Arizona

NASA Astrophysics Data System (ADS)

Malm, William C.; Johnson, Christopher E.

The relationship between airborne particulate matter and atmospheric light extinction was examined using the multivariate techniques of principal component analysis and multiple linear regression on data gathered at the Grand Canyon, Arizona, from December 1979 to November 1981. Results showed that, on the average, fine sulfates were most strongly associated with light attenuation in the atmosphere. Other fine mass (nitrates, organics, soot and carbonaceous material) and coarse mass (primarily windblown dust) were much less associated with atmospheric extinction. Fine sulfate mass at the Grand Canyon was responsible for 63% of atmospheric light extinction while other fine mass and coarse mass were responsible for 17 and 20% of atmospheric extinction, respectively.

The effects of wildfire on the peak streamflow magnitude and frequency, Frijoles and Capulin Canyons, Bandelier National Monument, New Mexico

USGS Publications Warehouse

Veenhuis, J.E.

2004-01-01

In June of 1977, the La Mesa fire burned 15,270 acres in and around Frijoles Canyon, Bandelier National Monument and the adjacent Santa Fe National Forest, New Mexico. The Dome fire occurred in April of 1996 in Bandelier National Monument, burned 16,516 acres in Capulin Canyon and the surrounding Dome Wilderness area. Both canyons are characterized by extensive archeological artifacts, which could be threatened by increased runoff and accelerated rates of erosion after a wildfire. The U.S. Geological Survey (USGS) in cooperation with the National Park Service monitored the fires' effects on streamflow in both canyons. Copyright 2004 ASCE.

Study of traffic-related pollutant removal from street canyon with trees: dispersion and deposition perspective.

PubMed

Morakinyo, Tobi Eniolu; Lam, Yun Fat

2016-11-01

Numerical experiments involving street canyons of varying aspect ratio with traffic-induced pollutants (PM 2.5 ) and implanted trees of varying aspect ratio, leaf area index, leaf area density distribution, trunk height, tree-covered area, and tree planting pattern under different wind conditions were conducted using a computational fluid dynamics (CFD) model, ENVI-met. Various aspects of dispersion and deposition were investigated, which include the influence of various tree configurations and wind condition on dispersion within the street canyon, pollutant mass at the free stream layer and street canyon, and comparison between mass removal by surface (leaf) deposition and mass enhancement due to the presence of trees. Results revealed that concentration level was enhanced especially within pedestrian level in street canyons with trees relative to their tree-free counterparts. Additionally, we found a dependence of the magnitude of concentration increase (within pedestrian level) and decrease (above pedestrian level) due to tree configuration and wind condition. Furthermore, we realized that only ∼0.1-3 % of PM 2.5 was dispersed to the free stream layer while a larger percentage (∼97 %) remained in the canyon, regardless of its aspect ratio, prevailing wind condition, and either tree-free or with tree (of various configuration). Lastly, results indicate that pollutant removal due to deposition on leaf surfaces is potentially sufficient to counterbalance the enhancement of PM 2.5 by such trees under some tree planting scenarios and wind conditions.

On the nature and origin of water masses in Herald Canyon, Chukchi Sea: Synoptic surveys in summer 2004, 2008, and 2009

NASA Astrophysics Data System (ADS)

Linders, Johanna; Pickart, Robert. S.; Björk, Göran; Moore, G. W. K.

2017-12-01

Hydrographic and velocity data from three high-resolution shipboard surveys of Herald Canyon in the northwest Chukchi Sea, in 2004, 2008, and 2009, are used to investigate the water masses in the canyon and their possible source regions. Both summer and winter Pacific waters were observed in varying amounts in the different years, although in general the summer waters resided on the eastern side of the canyon while the winter waters were located on the western flank. The predominant summer water was Bering summer water, although some Alaskan coastal water resided in the canyon in the two later years likely due to wind forcing. Both newly ventilated and remnant winter waters were found in the canyon, but the amount lessened in each successive survey. Using mooring data from Bering Strait it is shown that a large amount of Bering summer water in the western channel of the strait follows a relatively direct route into Herald Canyon during the summer months, with an estimated advective speed of 10-20 cm/s. However, while the winter water observed in 2004 was consistent with a Bering Strait source (with a slower advective speed of 5-8 cm/s), the dense water in the canyon during 2008 and 2009 was more in line with a northern source. This is consistent with sections to the west of the canyon and with previously reported measurements implying winter water formation on the East Siberian shelf. Large-scale wind patterns and polynya activity on the shelf are also investigated. It was found that the former appears to impact more strongly the presence of dense water in Herald Canyon.

Large eddy simulation of fire-induced buoyancy driven plume dispersion in an urban street canyon under perpendicular wind flow.

PubMed

Hu, L H; Huo, R; Yang, D

2009-07-15

The dispersion of fire-induced buoyancy driven plume in and above an idealized street canyon of 18 m (width) x 18 m (height) x 40 m (length) with a wind flow perpendicular to its axis was investigated by Fire Dynamics Simulator (FDS), Large Eddy Simulation (LES). Former studies, such as that by Oka [T.R. Oke, Street design and urban canopy layer climate, Energy Build. 11 (1988) 103-113], Gayev and Savory [Y.A. Gayev, E. Savory, Influence of street obstructions on flow processes within street canyons. J. Wind Eng. Ind. Aerodyn. 82 (1999) 89-103], Xie et al. [S. Xie, Y. Zhang, L. Qi, X. Tang, Spatial distribution of traffic-related pollutant concentrations in street canyons. Atmos. Environ. 37 (2003) 3213-3224], Baker et al. [J. Baker, H. L. Walker, X. M. Cai, A study of the dispersion and transport of reactive pollutants in and above street canyons--a large eddy simulation, Atmos. Environ. 38 (2004) 6883-6892] and Baik et al. [J.-J. Baik, Y.-S. Kang, J.-J. Kim, Modeling reactive pollutant dispersion in an urban street canyon, Atmos. Environ. 41 (2007) 934-949], focus on the flow pattern and pollutant dispersion in the street canyon with no buoyancy effect. Results showed that with the increase of the wind flow velocity, the dispersion pattern of a buoyant plume fell into four regimes. When the wind flow velocity increased up to a certain critical level, the buoyancy driven upward rising plume was re-entrained back into the street canyon. This is a dangerous situation as the harmful fire smoke will accumulate to pollute the environment and thus threaten the safety of the people in the street canyon. This critical re-entrainment wind velocity, as an important parameter to be concerned, was further revealed to increase asymptotically with the heat/buoyancy release rate of the fire.

Repeat Mapping in the Lower Monterey Submarine Canyon Sheds Light on Morphological Change During Discrete Sediment Density Flow Events

NASA Astrophysics Data System (ADS)

Anderson, K.; Lundsten, E. M.; Caress, D. W.; Thomas, H. J.; Paull, C. K.; Maier, K. L.; Gales, J. A.; Gwiazda, R.; Talling, P.; Xu, J.; Parsons, D. R.

2017-12-01

The Coordinated Canyon Experiment (CCE), a multi-institutional collaboration effort, was designed to monitor the passage of sediment density flows along the axis of Monterey Canyon, offshore California, between 200 and 1850 m water depth. An array of moorings and sensors were deployed for three 6-month periods from October 2015 to April 2017. Aligned with the CCE deployments, repeat high-resolution multibeam bathymetric surveys of the Monterey Canyon floor were conducted with a mapping AUV (Autonomous Underwater Vehicle). The AUV carried a Reson 7125 multibeam echosounder (vertical precision of 0.15 m and horizontal resolution of 1.0 m). An inertial navigation system combined with a Doppler velocity logger allowed the AUV to fly pre-programmed grids at 3 knots, while maintaining an altitude of 50 m above the seafloor, to obtain a nominal line spacing of 130 m. The floor and lower flanks of the canyon between 200 to 540 m and 1350 to 1880 m water depths were mapped six times during the CCE. These repeat maps are subtracted to create bathymetry difference grids to show morphological change. Coupling the sensor observations with the bathymetric surveys, the CCE successfully documented sediment density flow events as well as the associated changes in seafloor morphology. Between repeat surveys, three sediment density flow events reached the lower canyon, extending to at least 1850 m water depth. On January 15, 2016, a particularly large density flow traveled more than 50 km down Monterey Canyon. Unlike in the upper canyon where this event caused wholesale reorganization of geomorphological features, changes to the lower canyon morphology involved a more moderate re-sculpting of the features. The effect of a sediment density flow of known magnitude and duration on the seafloor morphology has never been documented in a deep-sea setting before.

Topographic change detection at select archeological sites in Grand Canyon National Park, Arizona, 2007–2010

USGS Publications Warehouse

Collins, Brian D.; Corbett, Skye C.; Fairley, Helen C.; Minasian, Diane L.; Kayen, Robert; Dealy, Timothy P.; Bedford, David R.

2012-01-01

Human occupation in Grand Canyon, Arizona, dates from at least 11,000 years before present to the modern era. For most of this period, the only evidence of human occupation in this iconic landscape is provided by archeological sites. Because of the dynamic nature of this environment, many archeological sites are subject to relatively rapid topographic change. Quantifying the extent, magnitude, and cause of such change is important for monitoring and managing these archeological sites. Such quantification is necessary to help inform the continuing debate on whether and how controlled releases from Glen Canyon Dam, located immediately upstream of Grand Canyon National Park, are affecting site erosion rates, artifact transport, and archeological resource preservation along the Colorado River in Grand Canyon. Although long-term topographic change resulting from a variety of natural processes is inherent in the Grand Canyon region, continued erosion of archeological sites threatens both the archeological resources and our future ability to study evidence of past cultural habitation. Thus, this subject is of considerable interest to National Park Service managers and other stakeholders in the Glen Canyon Dam Adaptive Management Program. Understanding the causes and effects of archeological site erosion requires a knowledge of several factors, including the location, timing, and magnitude of the changes occurring in relation to archeological resources, the rates of change, and the relative contribution of potential causes. These potential causes include sediment depletion associated with managed flows from Glen Canyon Dam, site-specific weather and overland flow patterns, visitor impacts, and long-term regional climate change. To obtain this information, highly accurate, spatially specific data are needed from sites undergoing change. Using terrestrial lidar techniques, and building upon three previous surveys of archeological sites performed in 2006 and 2007, we

"The Great Cataract" - Effects of Late Holocene Debris Flows on Lava Falls Rapid, Grand Canyon National National Park, Arizona

USGS Publications Warehouse

Webb, Robert H.; Melis, Theodore S.; Wise, Thomas W.; Elliott, John G.

1996-01-01

Lava Falls Rapid is the most formidable reach of whitewater on the Colorado River in Grand Canyon and is one of the most famous rapids in the world. Although the rapid was once thought to be controlled by the remnants of lava dams of Pleistocene age, Lava Falls was created and is maintained by frequent debris flows from Prospect Canyon. We used 232 historical photographs, of which 121 were replicated, and 14C and 3He dating methods to reconstruct the ages and, in some cases, the magnitudes of late Holocene debris flows. We quantified the interaction between Prospect Canyon debris flows and the Colorado River using image processing of the historical photographs. The highest and oldest debris-flow deposits on the debris fan yielded a 3He date of 2.9?0.6 ka (950 BC), which indicates predominately late Holocene aggradation of one of the largest debris fans in Grand Canyon. The deposit, which has a 25-m escarpment caused by river reworking, crossed the Colorado River and raised its base level by 30 m for an indeterminate, although probably short, period. We mapped depositional surfaces of 6 debris flows that occurred after 950 BC. The most recent prehistoric debris flow occurred no more than 500 years ago (AD 1434). From April 1872 to July 1939, no debris flows occurred in Prospect Canyon. Debris flows in 1939, 1954, 1955, 1963, 1966, and 1995 constricted the Colorado River between 35 and 80 percent and completely changed the pattern of flow through the rapid. The debris flows had discharges estimated between about 290 and 1,000 m3/s and transported boulders as heavy as 30 Mg. The recurrence interval of these debris flows, calculated from the volume of the aggraded debris fan, ranged from 35 to 200 yrs. The 1939 debris flow in Prospect Canyon appears to have been the largest debris flow in Grand Canyon during the last 125 years. Debris flows in Prospect Canyon are initiated by streamflow pouring over a 325-m waterfall onto unconsolidated colluvium, a process called the

Numerical study on the impact of ground heating and ambient wind speed on flow fields in street canyons

NASA Astrophysics Data System (ADS)

Li, Lei; Yang, Lin; Zhang, Li-Jie; Jiang, Yin

2012-11-01

The impact of ground heating on flow fields in street canyons under different ambient wind speed conditions was studied based on numerical methods. A series of numerical tests were performed, and three factors including height-to-width (H/W) ratio, ambient wind speed and ground heating intensity were taken into account. Three types of street canyon with H/W ratios of 0.5, 1.0 and 2.0, respectively, were used in the simulation and seven speed values ranging from 0.0 to 3.0 m s-1 were set for the ambient wind speed. The ground heating intensity, which was defined as the difference between the ground temperature and air temperature, ranged from 10 to 40 K with an increase of 10 K in the tests. The results showed that under calm conditions, ground heating could induce circulation with a wind speed of around 1.0 m s-1, which is enough to disperse pollutants in a street canyon. It was also found that an ambient wind speed threshold may exist for street canyons with a fixed H/W ratio. When ambient wind speed was lower than the threshold identified in this study, the impact of the thermal effect on the flow field was obvious, and there existed a multi-vortex flow pattern in the street canyon. When the ambient wind speed was higher than the threshold, the circulation pattern was basically determined by dynamic effects. The tests on the impact of heating intensity showed that a higher ground heating intensity could strengthen the vortical flow within the street canyon, which would help improve pollutant diffusion capability in street canyons.

Photomosaics and logs of trenches on the San Andreas Fault at Mill Canyon near Watsonville, California

USGS Publications Warehouse

Fumal, Thomas E.; Dawson, Timothy E.; Flowers, Rebecca; Hamilton, John C.; Heingartner, Gordon F.; Kessler, James; Samrad, Laura

2004-01-01

We present photomosaics and logs of the walls of trenches excavated for a paleoseismic study at Mill Canyon, one of two sites along the San Andreas fault in the Santa Cruz Mtns. on the Kelley-Thompson Ranch. This site was a part of Rancho Salsipuedes begining in 1834. It was purchased by the present owner’s family in 1851. Remnants of a cabin/mill operations still exist up the canyon dating from 1908 when the area was logged. At this location, faulting has moved a shutter ridge across the mouth of Mill Canyon ponding Holocene sediment. Recent faulting is confined to a narrow zone near the break in slope.

Nearshore temperature findings for the Colorado River in Grand Canyon, Arizona: possible implications for native fish

USGS Publications Warehouse

Ross, Robert P.; Vernieu, William S.

2013-01-01

Since the completion of Glen Canyon Dam, Arizona, in 1963, downstream water temperatures in the main channel of the Colorado River in Glen, Marble, and Grand Canyons are much colder in summer. This has negatively affected humpback chub (Gila cypha) and other native fish adapted to seasonally warm water, reducing main-channel spawning activity and impeding the growth and development of larval and juvenile fish. Recently published studies by U.S. Geological Survey scientists found that under certain conditions some isolated nearshore environments in Grand Canyon allow water to become separated from the main-channel current and to warm, providing refuge areas for the development of larval and juvenile fish.

27. YCC CREW THAT REBUILT PIMA POINT TRAILS. TIM BEALE, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

27. YCC CREW THAT REBUILT PIMA POINT TRAILS. TIM BEALE, NPS TRAILS, FRONT ROW RIGHT; BERNIE PONYAH, NPS YCC SUPERVISOR, BACK ROW RIGHT. - West Rim Drive, Between Grand Canyon Village & Hermit Rest, Grand Canyon, Coconino County, AZ

1. VIEW OF STAFF HOUSE (FEATURE 10), FACING SOUTHWEST. DUPLEX ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. VIEW OF STAFF HOUSE (FEATURE 10), FACING SOUTHWEST. DUPLEX (FEATURE 7) IS VISIBLE IN THE BACKGROUND AT RIGHT. - Copper Canyon Camp of the International Smelting & Refining Company, Staff House, Copper Canyon, Battle Mountain, Lander County, NV

Morphology, sedimentary features and evolution of a large palaeo submarine canyon in Qiongdongnan basin, Northern South China Sea

NASA Astrophysics Data System (ADS)

Li, Xiangquan; Fairweather, Luke; Wu, Shiguo; Ren, Jianye; Zhang, Hongjie; Quan, Xiayun; Jiang, Tao; Zhang, Cheng; Su, Ming; He, Yunlong; Wang, Dawei

2013-01-01

The large Miocene-aged palaeo canyon that extents through the Qiongdongnan basin (QDNB) and Yinggehai basin (YGHB) of Northern South China Sea has been of considerable interest both economically and scientifically over the past decade. Stemmed from this, significant research has been employed into understanding the mechanism for its existence, incision, and sedimentary fill, yet debate remains. In the first case the canyon itself is actually quite anomalous. Alone from the size (over 570 km in length and more than 8 km in width (Yuan et al., 2009)), which is considerably more than most ancient deep-water channels (REFS), the canyon's sedimentary fill is also distinctly different. Some explanations have been given to explain the canyon's origin and existence, these include increased sediment supply from the Red River which is genetically linked to uplift of the Tibetan Plateau, lowstand turbidite and mass-transport activity, reactivation and dextral displacement of the Red River Fault zone inducing erosive gravity-flows, regional tilt of the QDNB and YGHB, paleo-seafloor morphology and seal-level fluctuations. With the application of new data obtained from interpretations of a large number of 2D seismic profiles, core and well log data, and tectonic and sedimentary analysis this contribution aims to: (1) Present models to explain the Canyon's sedimentary fill and basin plain deposits, which provided significant understanding of processes pre-, syn- and post-incision and; (2) review the plausibility and likelihood of each of the controlling mechanisms, hoping to shed light on this controversial aspect. We conclude that the final erosive event that shaped the canyon is dated at 5.5 Ma. The Canyon's unusual fill is a product of variation in the interaction between turbidity currents and MTD that blocked the canyon's axis, and the reduction in gravity flow energy through time; and therefore the complete succession represents one major erosive and cut event at 5.5 Ma and

High spatiotemporal variability in meiofaunal assemblages in Blanes Canyon (NW Mediterranean) subject to anthropogenic and natural disturbances

NASA Astrophysics Data System (ADS)

Román, Sara; Vanreusel, Ann; Romano, Chiara; Ingels, Jeroen; Puig, Pere; Company, Joan B.; Martin, Daniel

2016-11-01

We investigated the natural and anthropogenic drivers controlling the spatiotemporal distribution of the meiofauna in the submarine Blanes Canyon, and its adjacent western slope (NW Mediterranean margin of the Iberian Peninsula). We analyzed the relationships between the main sedimentary environmental variables (i.e. grain size, Chl-a, Chl-a: phaeopigments, CPE, organic carbon and total nitrogen) and the density and structure of the meiofaunal assemblages along a bathymetric gradient (from 500 to 2000 m depth) in spring and autumn of 2012 and 2013. Twenty-one and 16 major taxa were identified for respectively the canyon and slope, where the assemblages were always dominated by nematodes. The gradual decreasing meiofaunal densities with increasing depth at the slope showed little variability among stations and corresponded with a uniform pattern of food availability. The canyon was environmentally much more variable and sediments contained greater amounts of food resources (Chl-a and CPE) throughout, leading not only to increased meiofaunal densities compared to the slope, but also different assemblages in terms of composition and structure. This variability in the canyon is only partly explained by seasonal food inputs. The high densities found at 900 m and 1200 m depth coincided with significant increases in food availability compared to shallower and deeper stations in the canyon. Our results suggest that the disruption in expected bathymetric decrease in densities at 900-1200 m water depth coincided with noticeable changes in the environmental variables typical for disturbance and deposition events (e.g., higher sand content and CPE), evoking the hypothesis of an anthropogenic effect at these depths in the canyon. The increased downward particle fluxes at 900-1200 m depth caused by bottom trawling along canyon flanks, as reported in previous studies, support our hypothesis and allude to a substantial anthropogenic factor influencing benthic assemblages at these

The impact of traffic-flow patterns on air quality in urban street canyons.

PubMed

Thaker, Prashant; Gokhale, Sharad

2016-01-01

We investigated the effect of different urban traffic-flow patterns on pollutant dispersion in different winds in a real asymmetric street canyon. Free-flow traffic causes more turbulence in the canyon facilitating more dispersion and a reduction in pedestrian level concentration. The comparison of with and without a vehicle-induced-turbulence revealed that when winds were perpendicular, the free-flow traffic reduced the concentration by 73% on the windward side with a minor increase of 17% on the leeward side, whereas for parallel winds, it reduced the concentration by 51% and 29%. The congested-flow traffic increased the concentrations on the leeward side by 47% when winds were perpendicular posing a higher risk to health, whereas reduced it by 17-42% for parallel winds. The urban air quality and public health can, therefore, be improved by improving the traffic-flow patterns in street canyons as vehicle-induced turbulence has been shown to contribute significantly to dispersion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Epizootiology of Tacaribe serocomplex viruses (Arenaviridae) associated with neotomine rodents (Cricetidae, Neotominae) in southern California.

PubMed

Milazzo, Mary Louise; Cajimat, Maria N B; Mauldin, Matthew R; Bennett, Stephen G; Hess, Barry D; Rood, Michael P; Conlan, Christopher A; Nguyen, Kiet; Wekesa, J Wakoli; Ramos, Ronald D; Bradley, Robert D; Fulhorst, Charles F

2015-02-01

The objective of this study was to advance our knowledge of the epizootiology of Bear Canyon virus and other Tacaribe serocomplex viruses (Arenaviridae) associated with wild rodents in California. Antibody (immunoglobulin G [IgG]) to a Tacaribe serocomplex virus was found in 145 (3.6%) of 3977 neotomine rodents (Cricetidae: Neotominae) captured in six counties in southern California. The majority (122 or 84.1%) of the 145 antibody-positive rodents were big-eared woodrats (Neotoma macrotis) or California mice (Peromyscus californicus). The 23 other antibody-positive rodents included a white-throated woodrat (N. albigula), desert woodrat (N. lepida), Bryant's woodrats (N. bryanti), brush mice (P. boylii), cactus mice (P. eremicus), and deer mice (P. maniculatus). Analyses of viral nucleocapsid protein gene sequence data indicated that Bear Canyon virus is associated with N. macrotis and/or P. californicus in Santa Barbara County, Los Angeles County, Orange County, and western Riverside County. Together, analyses of field data and antibody prevalence data indicated that N. macrotis is the principal host of Bear Canyon virus. Last, the analyses of viral nucleocapsid protein gene sequence data suggested that the Tacaribe serocomplex virus associated with N. albigula and N. lepida in eastern Riverside County represents a novel species (tentatively named "Palo Verde virus") in the genus Arenavirus.

Estimating recruitment dynamics and movement of rainbow trout (Oncorhynchus mykiss) in the Colorado River in Grand Canyon using an integrated assessment model

USGS Publications Warehouse

Korman, Josh; Martell, Steven J.D.; Walters, Carl J.; Makinster, Andrew S.; Coggins, Lewis G.; Yard, Michael D.; Persons, William R.

2012-01-01

We used an integrated assessment model to examine effects of flow from Glen Canyon Dam, Arizona, USA, on recruitment of nonnative rainbow trout (Oncorhynchus mykiss) in the Colorado River and to estimate downstream migration from Glen Canyon to Marble Canyon, a reach used by endangered native fish. Over a 20-year period, recruitment of rainbow trout in Glen Canyon increased with the annual flow volume and when hourly flow variation was reduced and after two of three controlled floods. The model predicted that approximately 16 000 trout·year–1 emigrated to Marble Canyon and that the majority of trout in this reach originate from Glen Canyon. For most models that were examined, over 70% of the variation in emigration rates was explained by variation in recruitment in Glen Canyon, suggesting that flow from the dam controls in large part the extent of potential negative interactions between rainbow trout and native fish. Controlled floods and steadier flows, which were originally aimed at partially restoring conditions before the dam (greater native fish abundance and larger sand bars), appear to have been more beneficial to nonnative rainbow trout than to native fish.

Seasonal pathways of organic matter within the Avilés submarine canyon: Food web implications

NASA Astrophysics Data System (ADS)

Romero-Romero, Sonia; Molina-Ramírez, Axayacatl; Höfer, Juan; Duineveld, Gerard; Rumín-Caparrós, Aitor; Sanchez-Vidal, Anna; Canals, Miquel; Acuña, José Luis

2016-11-01

The transport and fate of organic matter (OM) sources within the Avilés submarine canyon (Cantabrian Sea, Southern Bay of Biscay) were studied using carbon and nitrogen stable isotope ratios. The isotopic composition of settling particles and deep bottom sediments closely resembled that of surface particulate OM, and there were no marked differences in the isotopic composition of settling particles inside and outside of the AC. This indicates that the Avilés Canyon (AC) receives inputs of sinking OM mostly from the upper water column and less through advective near-bottom down-canyon transport. Sinking OM fluxes are of marine and terrestrial origin in proportions which vary seasonally. Analysis of δ13C in the canyon fauna indicates a dependence on OM mainly produced by marine phytoplankton. A tight coupling of isotopic signatures between pelagic organisms and benthic suspension feeders reflects an active biological vertical transport of OM from the surface to the deep-sea. The food web presented seasonal variations in the trophic niche width and the amplitude of the primary carbon sources, reflecting seasonality in the availability of fresh particulate OM. Those seasonal changes are larger for benthic organisms of lower trophic levels.

Aliso Canyon facility is giant among gas storage projects. [Underground

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magruder, P.S.

1975-11-01