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1

Valles Marineris: The Grand Canyon of Mars  

NSDL National Science Digital Library

This resource provides a general description of this system of canyons located just south of the Martian equator. Included are various images of the terrain: some photographic, some constructed from remotely sensed datasets. One set of images is presented in stereo and must be viewed with 3D glasses.

2

Fly in 3D over the Valles Marineris Canyon on Mars (title provided or enhanced by cataloger)  

NSDL National Science Digital Library

This interactive activity lets you explore the Valles Marineris canyon (the size of the US) and a piece of it called the Candor Chasm. Using a 3D model of Mars' surface created using data from orbiting spacecraft, you can examine the surface from a distance, changing lighting to enhance features, and fly over the surface, looking for markers hidden in the terrain. Informative feedback makes the exercise educational as well as fun.

Barstow, Daniel

2003-12-15

3

Valles Marineris Graben  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

This VIS image was taken just south of the rim of Valles Marineris. The troughs seen in this image are structural features called graben. A graben is formed when two parallel fractures bound a down-dropped block of surface. These graben developed as part of the formation of Valles Marineris.

Image information: VIS instrument. Latitude -14.1, Longitude 287.2 East (72.8 West). 19 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2005-01-01

4

Scarp development in the Valles Marineris  

NASA Technical Reports Server (NTRS)

The scarps along the margins of the Vales Marineris display a complex assemblage of forms that have been related to a variety of mass wasting and sapping processes. These scarp segments display variations in the degree of development of spur and gully topography, the number and density of apparent sapping features and the frequency of large scale landslides which reflect the age, geology and processes of slope development throughout the Valles Marineris. This regional analysis should provide more information on the geologic evolution of the Valles Marineris as well as new insight into the relative importance of different processes in the development of the scarp forms. In order to evaluate the regional variation in scarp form and the influence of time and structure on scarp development geomorphic mapping and morphometric analysis of geologically distinct regions of Valles Marineris is being undertaken.

Patton, P. C.

1984-01-01

5

Flight Into Mariner Valley (Valles Marineris, Mars)  

E-print Network

----------------------------------------------------------------------------------------------------- ------------------------- This work was sponsored by NASA's Science Mission Directorate Mars Exploration Program and was producedFlight Into Mariner Valley (Valles Marineris, Mars) Presented by Phil Christensen Mars Space Flight for the Mars Exploration Directorate, Mars Odyssey Project, Solar System Visualization Project, Research

Waliser, Duane E.

6

Noctis Labyrinthus/Valles Marineris transition  

NASA Technical Reports Server (NTRS)

(Released 27 May 2002) The Science The transition zone between maze-like troughs of Noctis Labyrinthus and the main Valles Marineris canyon system are shown in this THEMIS visible camera image. This huge system of troughs near the equator of Mars was most likely created by tectonic forces which pulled apart the crust. In the top third of the image, on the western side of the northernmost trough, a buildup of relatively bright material on the plateau has led to an overflow into the trough. Most of the bottom of this trough is covered by sediment deposited from the plateau above. On the right-hand side of this same trough, on the southern wall, there is a thin streak of darker material that also seems to originate from the plateau above. This is most likely a gully formation. This feature could also be a dust avalanche, but because no other similar features are seen, this is unlikely. Other dark material deposited by some unknown process can also be seen all around the easternmost ridge in the trough. Near the bottom of the canyon, layers from the center ridges and the canyon wall can be matched, indicating that the ridges are made of the same material as the wall. Near the bottom of the image, there is yet another depression. This trough is filled with sediment deposited from erosion of the trough wall and possibly from the plateau above. All around the walls of this trough a layer of rocky material can be also be seen. It appears that the areas directly below the rocky ledges are 'shielded' from landslide material from above. Finally, in the northwestern wall of this trough, there is an irregular pattern of very bright material not seen anywhere else in the image. Identifying similar formations in other THEMIS visible camera images could provide some context for its occurrence and help us understand how it was formed. The Story Tectonic forces wrenched apart the crust on Mars long ago, forming deep troughs at the Martian equator like the ones seen here. They occur in a transition zone between the maze-like region of Noctis Labyrinthus and the deep canyon system of Valles Marineris, the largest and 'grandest' canyon in the solar system. These cracks in the crust can give geologists a good idea of what has happened over the course of the planet's history. Find out a little yourself by taking a closer look at the western side of the trough in the top third of the image. Can you see how the bright sediment from the plateau above has been whisked over the side, overflowing and building up on the floor below? Follow the south wall of this same trough, and you'll come across a dark streak running down (toward the right side of the image). One possibility is that it could be a dust avalanche, but if that were so, you'd think it would have occurred much more often, in more places than just that one spot. Since it didn't, scientists believe it probably isn't a dust avalanche, but could be a gully instead. There's also some more dark material deposited all around the easternmost ridge in the trough as well. No one is quite sure how it formed there or exactly what it's made of. At the least, what geologists can tell is that the ridges in the trough are made of the same material as the canyon walls, since the layers in each of them match. Finding similarities like these can help piece together the story of Martian geology here. When scientists study THEMIS images, however, they are also on the lookout for anything that looks unusual. Try studying the dark depression that carves out the bottom of this image. It too is filled soft-looking sediments, probably deposited from erosion of the trough wall and possibly from the plateau above. Rocky outcrops all around the walls of this trough shield the areas directly below them from landslides from above. But all that seems pretty regular. Do you see anything that stands out? How about the odd pattern of brighter material that seems almost pasted on the northwestern wall of the trough like dried up glue? This material isn't found elsewhere in this image.

2002-01-01

7

The Layer Cake Walls of Valles Marineris  

NASA Technical Reports Server (NTRS)

This image of the northern wall of Coprates Chasma, in Valles Marineris, was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 1227 UTC (8:27 a.m. EDT) on June 16, 2007, near 13.99 degrees south latitude, 303.09 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 20 meters (66 feet) across. The region covered is just over 10 kilometers (6.2 miles) wide at its narrowest point.

Valles Marineris is a large canyon system straddling Mars' equator, with a total size approximating the Mediterranean Sea emptied of water. It is subdivided into several interconnected 'chasmata' each hundreds of kilometers wide and, in some cases, thousands of kilometers long. The walls of several of the chasmata, including Coprates Chasma, expose a section of Mars' upper crust about 5 kilometers (3 miles) in depth. Exposures like these show the layers of rock that record the formation of Mars' crust over geologic time, much as the walls of the Grand Canyon on Earth show part of our planet's history.

The upper panel of this montage shows the location of the CRISM image on a mosaic from the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS), taken in longer infrared wavelengths than measured by CRISM. The CRISM image samples the base of Coprates Chasma's wall, including a conspicuous horizontal band that continues along the wall for tens of kilometers to the east and west, and a topographic shelf just above that.

The middle two panels show the CRISM image in visible and infrared light. In the middle left panel, the red, green, and blue image planes show brightness at 0.59, 0.53, and 0.48 microns, similar to what the human eye would see. Color variations are subdued by the presence of dust on all exposed surfaces. In the middle right panel, the red, green, and blue image planes show brightness at 2.53, 1.51, and 1.08 microns. These three infrared wavelengths are the 'usual' set that the CRISM team uses to provide an overview of infrared data, because dust has a less obscuring effect, and because they are sensitive to a wide variety of minerals. Layering is clearly evident in the wall rocks. The conspicuous band running along the base of the chasma wall appears slightly yellowish, and the scarp at the edge of the topographic bench appears slightly green.

The bottom two panels use combinations of wavelengths to show the strengths of absorptions that provide 'fingerprints' of different minerals. In the lower left panel, red shows strength of a 0.53-micron absorption due to oxidized iron in dust, green shows strength of an inflection in the spectrum at 0.6 microns that may be related to rock coatings, and blue shows strength of a 1-micron absorption due to the igneous minerals olivine and pyroxene. The conspicuous horizontal band appears slightly blue, indicating a stronger signature of olivine and/or pyroxene. In the lower right panel, red is a measure of an absorption particular to olivine, green is a measure of a 2.3-micron absorption due to phyllosilicates (clay-like minerals formed when rock was subjected to liquid water), and blue is a measure of absorptions particular to pyroxene. The conspicuous horizontal band is now resolved into an upper portion richer in pyroxene, underlain by material richer in olivine than the rest of the wall rock. Also, erosion-resistant material forming the topographic bench is underlain by phyllosilicate-containing material exposed on the scarp.

Taken together, these data reveal a layer cake-like composition of the crustal material exposed in Coprates Chasma's wall. Most of the rock is rich in pyroxene, which is expected because much of Mars' crust consists of volcanic basaltic rock. However discrete layers are richer in olivine, and in some layers the presence of phyllosilicates indicates interaction of rock with liquid water. Because the phyllosilicate-containing layer is low on the walls and deeply buried, it likely represents an early pe

2007-01-01

8

High-Resolution Apparent Thermal Inertia Mapping of Valles Marineris (Mars)  

NASA Astrophysics Data System (ADS)

The apparent thermal inertia map, broadband emissivity and Lambert albedo in Valles Marineris have been calculated using THEMIS/MO and CTX/MRO data. They will be used in the characterization of Valles Marineris landforms.

Kubiak, M.; Mège, D.; Gurgurewicz, J.; Ci??ela, J.; D?bniak, K.

2014-07-01

9

Climbing and falling dunes in Valles Marineris, Mars Matthew Chojnacki,1  

E-print Network

Click Here for Full Article Climbing and falling dunes in Valles Marineris, Mars Matthew Chojnacki. Newly acquired Mars Reconnaissance Orbiter (MRO) images and topography of the walls of Valles Marineris, and D. M. Burr (2010), Climbing and falling dunes in Valles Marineris, Mars, Geophys. Res. Lett., 37, L

Perfect, Ed

10

Evidence for ponding and catastrophic floods in central Valles Marineris, Mars  

USGS Publications Warehouse

The Valles Marineris canyon system of Mars is closely related to large flood channels, some of which emerge full born from chaotic terrain in canyon floors. Coprates Chasma, one of the largest Valles Marineris canyons, is connected at its west end to Melas Chasma and on its east end to chaotic terrain-filled Capri and Eos Chasmata. The area from central Melas to Eos Chasmata contains a 1500 km long and about 1 km deep depression in its floor. Despite the large volumes of groundwater that likely discharged from chaotic terrain in this depression, no evidence of related fluvial activity has thus far been reported. We present an analysis of the regional topography which, together with photogeologic interpretation of available imagery, suggests that ponding due to late Hesperian discharge of water possibly produced a lake (mean depth 842 m) spanning parts of the Valles Marineris depression (VMD). Overflow of this lake at its eastern end resulted in delivery of water to downstream chaos regions and outflow channels. Our ponding hypothesis is motivated primarily by the identification of scarp and terrace features which, despite a lateral spread of about 1500 km, have similar elevations. Furthermore, these elevations correspond to the maximum ponding elevation of the region (-3560 m). Simulated ponding in the VMD yields an overflow point at its eastern extremity, in Eos Chasma. The neighborhood of this overflow point contains clear indicators of fluvial erosion in a consistent east-west orientation. ?? 2008 Elsevier Inc.

Harrison, K. P.; Chapman, M. G.

2008-01-01

11

Evidence for ponding and catastrophic floods in central Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

The Valles Marineris canyon system of Mars is closely related to large flood channels, some of which emerge full born from chaotic terrain in canyon floors. Coprates Chasma, one of the largest Valles Marineris canyons, is connected at its west end to Melas Chasma and on its east end to chaotic terrain-filled Capri and Eos Chasmata. The area from central Melas to Eos Chasmata contains a 1500 km long and about 1 km deep depression in its floor. Despite the large volumes of groundwater that likely discharged from chaotic terrain in this depression, no evidence of related fluvial activity has thus far been reported. We present an analysis of the regional topography which, together with photogeologic interpretation of available imagery, suggests that ponding due to late Hesperian discharge of water possibly produced a lake (mean depth 842 m) spanning parts of the Valles Marineris depression (VMD). Overflow of this lake at its eastern end resulted in delivery of water to downstream chaos regions and outflow channels. Our ponding hypothesis is motivated primarily by the identification of scarp and terrace features which, despite a lateral spread of about 1500 km, have similar elevations. Furthermore, these elevations correspond to the maximum ponding elevation of the region (-3560 m). Simulated ponding in the VMD yields an overflow point at its eastern extremity, in Eos Chasma. The neighborhood of this overflow point contains clear indicators of fluvial erosion in a consistent east-west orientation.

Harrison, Keith P.; Chapman, Mary G.

2008-12-01

12

Formation of the layered deposits in the Valles Marineris, Mars  

NASA Technical Reports Server (NTRS)

Evidence is presented for large standing bodies of water on Mars during past epochs. It is noted that the origin of the horizontally-layered deposits in the Valles Marineris can be best explained by formation in standing bodies of water. These lakes, if they existed, were most likely covered by ice. There are several geologically feasible mechanisms that could have led to formation to thick deposits in ice covered paleolakes in the Valles Marineris. Present data are insufficient to choose conclusively among the various possibilities.

Nedell, S. S.; Squyres, S. W.

1987-01-01

13

Valles Marineris dune sediment provenance and pathways  

NASA Astrophysics Data System (ADS)

Although low-albedo sand is a prevalent component of the martian surface, sources and pathways of the sands are uncertain. As one of the principal present-day martian sediment sinks, the Valles Marineris (VM) rift system hosts a diversity of dune field populations associated with a variety of landforms that serve as potential sediment sources, including spur-and-gully walls, interior layered deposits (ILDs), and landslides. Here, we test the hypothesis that VM dune fields are largely derived from a variety of local and regional (intra-rift) sediment sources. Results show several dune fields are superposed on ancient wall massifs and ILDs that are topographically isolated from extra-rift sand sources. Spectral analysis of dune sand reveals compositional heterogeneity at the basinal-, dune field-, and dune-scales, arguing for discrete, relatively unmixed sediment sources. In Coprates and Melas chasmata, mapping is consistent with the principle sand source for dunes being Noachian-aged upper and lower wall materials composed of primary (igneous) minerals and glasses, some of which show evidence for alteration. In contrast, dune fields in Capri, Juventae, and Ganges chasmata show evidence for partial sediment derivation from adjacent Early Hesperian-aged hydrated sulfate-bearing ILD units. This finding indicates that these ILDs act as secondary sand sources. Dunes containing “soft” secondary minerals (e.g., monohydrated sulfate) are unlikely to have been derived from distant sources due to the physical weathering of sand grains during transport. Isolated extra-rift dune fields, sand sheets, and sand patches are located on the plateaus surrounding VM and the adjoining areas, but do not form interconnected networks of sand pathways into the rift. If past wind regimes (with respect to directionality and seasonality) were consistent with more recent regimes inferred from morphological analysis (i.e., dune slip faces, wind streaks), and were sufficient in strength and duration, small dune populations within Aurorae Chaos and north of eastern VM might have resulted from extended sand pathways into VM. However, we favor local and regional derivation of dune sand from a variety of intra-rift lithologic sources for most cases. Dune sand sources and the mechanism by which the sand is liberated are discussed in the context of findings described herein, but are broadly applicable to analysis of sediment production elsewhere on Mars.

Chojnacki, Matthew; Burr, Devon M.; Moersch, Jeffrey E.; Wray, James J.

2014-04-01

14

Characterization of Layered Deposits inside Valles Marineris  

NASA Technical Reports Server (NTRS)

This report represents the final progress report on our study of the Melas Chasma region on Mars that was proposed as a landing site for the Mars Exploration Rover mission (MER). During this two-year proposal (which was extended over three years by a no-cost extension), we conducted a thorough study of the layered deposits in western Melas Chasma that had been the location of a high priority MER mission landing ellipse within Valles Marineris. All available data sets from orbiter missions, including MOC, MOLA, THEMIS visible and infrared images were all used to analyze this site. The major outcome of this work was a published paper in the Journal of Geophysics and Research Planets [Weitz et al., 2004]. Our geologic mapping and interpretation of the MOC images suggest the landing ellipse contains three main geomorphologic units: (1) a blocky deposit consisting of bright blocks in a darker matrix (BD); (2) sand sheets composed of dark dunes; and (3) landslide deposits emanating from the wallrock to the west [Weitz et al., 2003]. Furthermore, we propose that the morphology of the BD unit in western Melas is a mass wasting deposit composed of blocks of Interior Layered Deposits (ILDs) mixed in with wallrock material. However, more recent MOC images indicate that in the eastern portion of the ellipse and adjacent to a large hill, there are blocks of material resembling those seen in BD. Hence, we cannot rule out the source of BD was this hill. Unfortunately, sand dunes obscure much of the deposit around this hill, making it impossible to precisely determine the connection between the hill and BD, whereas BD can be traced directly to the southern Melas wallrock. If BD resulted from a mass wasting event in the southern wallrock, then we would expect the material to be concentrated further to the north, as now appears to be the case. In summary, the exact source location for BD continues to remain a mystery, but we favor an origin from either the southern wallrock [Weitz et el., 2002] or the eastern hill.

Weitz, Catherine; Anderson, Scott; Parker, Tim; Grant, John

2005-01-01

15

Formation of the layered deposits in the Valles Marineris, Mars  

NASA Technical Reports Server (NTRS)

Thick sequences of layered deposits are found in the Valles Marineris, which exhibit fine, nearly horizontal layering, and are present as isolated plateaus of what were once more extensive deposits. It was argued that the morphology of the deposits is most consistent with origin in standing bodies of water. The conditions necessary for the existence of ice-covered Martian paleolakes are examined in detail and mechanisms for sediment deposition in them are considered. It was concluded that there are several geologically feasible mechanisms that could have led to the formation of thick deposits in ice-covered paleolakes in the Valles Marineris. Present data are insufficient to choose conclusively among the various possibilities. Several types of data from the Mars Observer mission will be useful in further characterizing the deposits and clarifying the process of their origin. The deposits should be considered important targets for a future Mars sample return mission.

Nedell, Susan S.; Squyres, Steven W.

1987-01-01

16

Part 2: Sedimentary geology of the Valles, Marineris, Mars and Antarctic dry valley lakes  

NASA Technical Reports Server (NTRS)

Detailed mapping of the layered deposits in the Valles Marineris, Mars from high-resolution Viking orbiter images revealed that they from plateaus of rhythmically layered material whose bases are in the lowest elevations of the canyon floors, and whose tops are within a few hundred meters in elevation of the surrounding plateaus. Four hypotheses for the origin of the layered deposits were considered: that they are eolian deposits; that they are remnants of the same material as the canyon walls; that they are explosive volcanic deposits; or that they were deposited in standing bodies of water. There are serious morphologic objections to each of the first three. The deposition of the layered deposits in standing bodies of water best explains their lateral continuity, horizontality, great thickness, rhythmic nature, and stratigraphic relationships with other units within the canyons. The Martian climatic history indicated that any ancient lakes were ice covered. Two methods for transporting sediment through a cover of ice on a martian lake appear to be feasible. Based on the presently available data, along with the theoretical calculations presented, it appears most likely that the layered deposits in the Valles Marineris were laid down in standing bodies of water.

Nedell, Susan S.

1987-01-01

17

Evidence of a Paleolake in the central Valles Marineris  

NASA Astrophysics Data System (ADS)

The Valles Marineris (VM) canyon system of Mars is closely related to large flooding channels, some of which emerge full born from chaotic terrain in canyon floors. Coprates Chasma, one of the largest VM canyons, is connected at its eastern end to chaotic terrain Capri Chasma. Despite the likely large volumes of groundwater that discharged from Capri Chasma [1], no evidence of related fluvial activity in Coprates Chasma has thus far been reported. We present an analysis of the regional topography which, together with photogeologic interpretation of available imagery, suggests that ponding due to late-stage discharge of water from Capri Chasma chaotic terrain produced a shallow lake spanning parts of Melas, Coprates, Capri and Eos Chasmata (MCCE). Overflow of this lake at its eastern end resulted in delivery of water to downstream chaos regions and outflow channels. Our ponding hypothesis is motivated primarily by the identification of scarp and terrace features which, despite a lateral spread of about 1500 km, have similar elevations. Furthermore, these elevations correspond to the maximum ponding elevation of the region (-3562 m). Mean lake depth is 842 m. Simulated ponding in the MCCE system yields an overflow point at its eastern extremity, in Eos Chasma. The neighborhood of this overflow point contains clear indicators of fluvial erosion in a consistent east-west orientation (Figure 4). Specifically, scour marks suggest an eastward convergence of flow lines. Downstream of the overflow point, the direction set by the scour marks is paved by a smooth deposit leading directly to a scoured channel entering the next major region of chaotic terrain, Aurorae Chaos. The smooth deposit is likely made up of remnants of the interior deposit breached by the MCCE paleolake overflow. The next region of chaotic terrain downstream of Aurorae Chasma is Hydraotes Chaos, which lies in a relatively deep depression and would be the next significant ponding location for flow originating in the MCCE region. Crucially, it is also the only other Chryse Planitia chaos to exhibit terraces, which have been attributed a lacustrine origin by other authors [2]. References: [1] Carr M. H. (1979) JGR, 84, 2995-3007. [2] Ori G. G. and Mosangini C. (1998) JGR, 103, 22713-22724.

Harrison, K. P.

2007-12-01

18

Melas Chasma: A Mars Pathfinder view of Valles Marineris  

NASA Technical Reports Server (NTRS)

A Mars Pathfinder landing site in Melas Chasma (Valles Marineris) would yield significant science return, but is outside present mission constraints. In Melas Chasma, Mars Pathfinder could investigate minimally altered basaltic material, sedimentary deposits, chemical weathering, tectonic features, the highland crust, equatorial weather, and Valles mists. Critical issues include the following: (1) nature and the origin of the Valles interior layered deposits, important for understanding water as a sedimentary and chemical agent, and for the past existence of of environments favorable for life; (2) compositions of little-altered basaltic sands, important for understanding magma genesis and weathering on Mars, and the martian meteorites; and (3) structure and composition of the highland crust, important for understanding Mars' early history .

Treiman, Allan H.; Murchie, Scott

1994-01-01

19

Valles Marineris, Mars: Are Pit Chains Formed by Erosion and Troughs by Tectonism.  

National Technical Information Service (NTIS)

The origin of the Valles Marineris remains controversial. Erosional, tectonic, and hybrid processes have been proposed. To clarify these contradictions, the widths and depths of pit chains and troughs were compared and it was found that the features do no...

B. K. Lucchitta, R. A. Balser, L. M. Bertolini

1991-01-01

20

Phyllosilicates in the Walls of Valles Marineris and the Tectonic Evolution of the Greater Tharsis Region  

NASA Astrophysics Data System (ADS)

Phyllosilicate marker beds rule out proposed tectonic mechanisms that predict lateral offset across Valles Marineris. Deposits in E. Coprates experienced localized thermal alteration, providing a window into the formation of the Thaumasia Highlands.

Viviano-Beck, C. E.; Murchie, S. L.

2014-07-01

21

FLEXURAL RESPONSE TO SEDIMENT EROSION AND UNLOADING AT VALLES MARINERIS, MARS. B. J. Davis1  

E-print Network

FLEXURAL RESPONSE TO SEDIMENT EROSION AND UNLOADING AT VALLES MARINERIS, MARS. B. J. Davis1 * and J layered deposits (ILD) on Mars remains as one of the most debated topics in Martian tectonics. The sub

22

New insights into the hydrologic history of western Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

Using Mars Reconnaissance Orbiter (MRO) Context (CTX) and High Resolution Imaging Science Experiment (HiRISE) image data in tandem with Mars Orbiter Laser Altimeter (MOLA) surface topography, we have characterized and mapped the remnants of an extensive flow feature that we interpret to be a debris flow within the floors of Tithonium Chasma and an adjacent canyon system in western Valles Marineris. The deposit appears highly modified by collapse and tectonic deformation consistent with a freezing and devolatization history, but shows no signs of resurfacing by catastrophic floods. Preliminary impact crater count statistics indicate the deposit was emplaced during the Early Hesperian, thereby defining a stratigraphic marker that constrains any major surface water discharges from Noctis Labyrinthus to the Noachian period.

Rodriguez, J. A. P.; Gulick, V. C.

2013-09-01

23

Impact craters and landslide volume distribution in Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

The landslides in the wide gorge system of Valles Marineris (Mars) exhibit volumes of the or-der of several hundred 1,000 km3 and runouts often in the excess of 80 km. Most landslides have occurred at the borders of the valleys, where the unbalanced weight of the 5-8 km high headwalls has been evidently sufficient to cause instability. Previous analysis has shown that the mechanical conditions of instability would not have been reached without external triggering fac-tors, if the wallslope consisted of intact rock. Among the factors that have likely promoted instability, we are currently analyzing: i) the possibility of rock weakening due to weathering; ii) the alternation of weak layers within more massive rock; weak layers might for example due to evaporites, the possible presence of ice table at some depth, or water; iii) weakening due to impact damage prior to the formation of Valles Marineris; studies of impact craters on Earth show that the volumes of damaged rock extends much deeper than the crater itself; iv) direct triggering of a landslide due to the seismic waves generated by a large meteoroid impact in the vicinity, and v) direct triggering of a landslide con-sequent to impact at the headwall, with impulsive release of momentum and short but intense increase of the triggering force. We gathered a large database for about 3000 Martian landslides that allow us to infer some of their statistical properties supporting our analyses, and especially to discriminate among some of the above listed predisposing and triggering factors. In particular, we analyse in this contribution the frequency distribution of landslide volumes starting from the assumption that these events are controlled by the extent of the shock damage zones. Relative position of the impact point and damage zones with respect to the Valles Marineris slopes could in fact control the released volumes. We perform 3D slope stability analy-sis under different geometrical constraints (e.g. crater size and position, slope angle and height, size of the relative shock damage zone) starting from rock mass properties calibrated in a previous study (Crosta et al., 2014). We report about the synthetic volume frequency distribution gen-erated by considering the most critical failure surfaces for the different geometrical constraints and the frequency distribution of craters on Mars surface (e.g., Hartmann and Neukum, 2001). 1. Crosta, G.B., Utili, S., De Blasio, F.V., Castellanza, R. (2014)Reassessing rock mass properties and slope instability triggering conditions in Valles Marineris, Mars.Earth Planetary Science Letters, 338, 329-343. http://dx.doi.org/10.1016/j.epsl.2013.11.053 2. Hartmann, W., and Neukum, G., (2001). Crater Chronology and the evolution of Mars. Space Science Reviews 96: 165-194.

De Blasio, Fabio

2014-05-01

24

Stratigraphic architectures spotted in southern Melas Chasma, Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

The distribution in space and time of liquid water on Mars is relevant to astrobiology and astroclimatology. To date, most orbital observations that attest to past fluvial and lacustrine activity on Mars have been dedicated to surficial landforms (i.e., drainage networks and depositional fans). Here we report an unprecedented identification of typical stratigraphic architectures made in Mars Global Surveyor Mars Orbiter Camera images of layered material in southern Melas Chasma. A particular set of strata is arranged in three depositional sequences bounded by stratigraphic unconformities. The sequences show spectacular steeply inclined clinoforms, and a broad channel-like depression. There are the same complex stratal patterns in Valles Marineris on Mars as there are in terrestrial deposits. Insights into these three-dimensional deposit geometries are used to tentatively isolate specific depositional processes and point to ancient subaqueous settings. Findings in southern Melas indicate a very attractive spot to which the search for ancient habitable environments on Mars could be directed.

Dromart, Gilles; Quantin, Cathy; Broucke, Olivier

2007-04-01

25

The formation of Valles Marineris: 2. Stress focusing along the buried dichotomy boundary  

NASA Astrophysics Data System (ADS)

Although Valles Marineris is widely regarded as an extensional tectonic feature, the source of stress responsible for its formation remains unknown. This study argues that the tensile stresses that triggered Valles Marineris tectonism are a result of its location south of and subparallel to the buried crustal dichotomy boundary beneath Tharsis. The emplacement of the Tharsis volcanic load straddling the pre-existing topographic step of the crustal dichotomy boundary would have resulted in an abrupt change in the thickness of the load, causing differential subsidence and extension across the boundary. Thin-shell flexural models predict a narrow belt of focused tensile stresses south of the buried dichotomy boundary, coinciding with the location of present-day Valles Marineris. The interaction of these boundary-generated stresses with the competing stress fields associated with Tharsis loading can explain the formation of Noctis Labyrinthus in the west, and the deflection of the Valles Marineris troughs away from the buried boundary toward the east. Finite element models demonstrate that the magnitudes and vertical variations of stress at Valles Marineris are sensitive to the timing of loading and flexure in Tharsis. The incremental loading and flexure expected for a large volcanic rise results in the maximum tensile stress at Valles Marineris occurring at depth, with tensile stresses through the majority of the lithospheric column. Dikes forming within this tensile stress belt would propagate through the full vertical extent of the lithosphere due to the stress release associated with the dilation of the dikes, playing a crucial role in the formation of the Valles Marineris troughs.

Andrews-Hanna, Jeffrey C.

2012-04-01

26

Age and erosion rates of sulfate-rich Interior Layered Deposits of Valles Marineris  

NASA Astrophysics Data System (ADS)

Since their discovery by Mariner 9, the Interior Layered Deposits (ILD) of Valles Marineris are still one of the most puzzling feature at the surface of Mars. Since the early investigation by the OMEGA spectrometer onboard Mars Express, it is known that these voluminous deposits are enriched in sulfates and may represent one of the largest reservoirs of hydrated minerals at the surface of Mars. Nowadays, with MRO dataset-especially HiRISE and CRISM-, we have a better knowledge of their composition, structure and stratigraphy. However, their age is still unknown and is subject of speculation. Three main theories are being debated. The first interprets the ILD to be older than Valles Marineris formation and to have been exhumed by the chasmata opening. Their composition enriched in sulfates is in agreement with this hypothesis; diapirism may have occurred. The second hypothesis argues that the ILD have filled the canyons during or right after their formation. Some observed stratigraphic relationships with the troughs are consistent with this hypothesis. The last theory argues that the ILD could be recent and be related to Amazonian equatorial ice deposition. One of the arguments supporting this theory is the lack of impact craters on the outcrops of these ILD, especially at high resolution. To address this question, we performed for each canyon of Valles Marineris a systematic analysis at high resolution of the stratigraphic relationship between the ILD and the others landforms observed in the canyon. We also systematically investigated the impact crater retention of the ILD over a large range of scales from chasmata scale to HiRISE image scale. We also counted crater on CTX images on landforms in stratigraphic relationship with the ILD. Our results allow us to deduce the timing of events and the erosion rates of the different surfaces. The investigation of stratigraphic relationships attests that the ILD postdate the formation of the canyons. Our crater counts on landforms postdating the ILD revealed that the ILD formed and were eroded early in the canyon history near 3.5 Gy. In almost each chasma, large impact craters have been emplaced on the ILD attesting to their old ages. The crater size distribution on ILD also reveals a long erosional history. Using the age deduced by that portion of the crater size distribution that follows the crater production slope, and the largest impact diameter not affected by erosion, we deduced the erosion rate of the different surfaces. At similar ages of formation, the ILD are one order in magnitude more erodible than others materials (landslides, trough floors...). According to these results, a simple aeolian erosion over the last 3.5 Gy is sufficient to explain the observed depletion in small impact craters on the ILD as compared to the surrounding surfaces.

Quantin, C.; Mangold, N.; Haubert, E.; Flahaut, J.; Le Deit, L.; Fueten, F.; Rossi, A.; Clenet, H.

2012-04-01

27

Sedimentation, volcanism, and ancestral lakes in the Valles Marineris: Clues from topography  

NASA Technical Reports Server (NTRS)

Compilation of a simplified geologic/geomorphic map onto a digital terrain model of Valles Marineris has permitted quantitative evaluations of topographic parameters. The study showed that, if their interior layered deposits are lacustrine, the ancestral Valles Marineris must have consisted of isolated basins. If, on the other hand, the troughs were interconnected as they are today, the deposits are most likely to volcanic origin, and the mesas in the peripheral troughs may be table mountains. The material eroded from the trough walls was probably not sufficient to form all of the interior layered deposits, but it may have contributed significantly to their formation.

Lucchitta, B. K.; Isbell, N. K.; Howington-Kraus, A.

1993-01-01

28

The Interior Layered Deposits of Valles Marineris: Layering, Erosional Processes, and Age Relationships  

NASA Technical Reports Server (NTRS)

We have used Viking and Mars Global Surveyor data to study the interior layered deposits in detail. We have identified features which may support fluvial activity within Valles Marineris. Stratigraphic relationships indicate the deposits are younger than the wallrock. Additional information is contained in the original extended abstract.

Weitz, C. M.; Parker, T.; Anderson, F. S.; Grant, J. A.

2001-01-01

29

Structural development of Coprates Chasma and western Ophir Planum, Valles Marineris Rift, Mars  

Microsoft Academic Search

A portion of Valles Marineris was mapped in detail in order to clarify the dominant processes responsible for the formation of Coprates Chasma. New crater counts indicate that the caprock on western Ophir Planum plateau has a Late Hesperian crater age, whereas trough floor preserved in western Coprates Chasma has an Early to Late Hesperian crater age. Caprock on western

Richard A. Schultz

1991-01-01

30

Landslides as Indicators of the Past Extent of Interior Layered Deposits in Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

Mounds of layered deposits, often several kilometres in height, are common in the canyons of Valles Marineris [1,2] and impact craters such as Gale Crater [3]. These interior layered deposits (ILDs) are important because they not only potentially preserve long sequences of Mars' stratigraphic record, but also because the common presence of abundant hydrous mineral phases implies aqueous activity crucial to studies of habitability. Despite their importance, no consensus exists regarding how ILDs form. Here we use landslides in Valles Marineris to gain insight into the previous extent and state of two large-scale ILDs. Using visible wavelength images and stereo digital terrain models we have identified three major occurrences of landslide deposits in Ophir Chasma, which are indicative of diversion or obstruction by material that is no longer present. The landslides in this study differ from most other landslides by increasing in height towards their front edges, showing distinctive concave scarp faces that are up to 500 m above the base level, and up to 400 m higher than the preceding part of the landslide deposit. These scarps are 1 - 2 km from, and mimic the shape of, the current extent of the ILD outer boundaries. Although not continuous throughout Ophir Chasma, the scarps extend between 20 and 50 km in length at different landslides, suggesting a common boundary at the northern edge of Ophir/Baetis Mensae. The most likely explanation for the formation of these scarps is that the leading edge of a landslide has piled up in front of an obstacle that has since been removed. Given the short timescale between landslide formation and the removal of the ILD obstacle material [4], it is likely that erosion alone is incapable of removing the material unless unrealistically high rates are assumed. Instead ice sublimation processes are likely to have been the dominant removal method, which implies that a significant amount of ice was present in the ILDs during the Amazonian [4]. References: [1] Nedell, S.S., et al. (1987), Icarus, 70, 409-441. [2] Lucchitta, B.K., et al. (1994), JGR, 99, 3783-3798. [3] Malin, M.C., K.S. Edgett (2000), Science, 290, 1927-1937. [4] Quantin, C., et al. (2004), Icarus, 172, 555.572.

Grindrod, Peter; Warner, Nicholas

2014-05-01

31

Topography of Valles Marineris: Implications for erosional and structural history  

NASA Astrophysics Data System (ADS)

Compilation of a simplified geologic/geomorphic map onto digital terrain models of the Valles Marineris permitted an evaluation of elevations in the vicinity of the troughs and the calculation of depth of troughs below surrounding plateaus, thickness of deposits inside the troughs, volumes of void spaces above geologic/geomorphic units, and volumes of deposits. The central troughs north Ophir, north and central Candor, and north Melas Chasmata lie as much as 11 km below the adjacent plateaus. In Ophir and Candor chasmata, interior layered deposits reach 8 km in elevation. If the deposits are lacustrine and if all troughs were interconnected, lake waters standing 8 km high would have spilled out of Coprates Chasma onto the surrounding plateaus having surface elevations of only 4-5 km. On the other hand, the troughs may not have been interconnected at the time of interior-deposit emplacement; they may have formed isolated ancestral basins. The existence of such basins is supported by independent structural and stratigraphic evidence. The ancestral basins may have eventually merged, perhaps through renewed faulting, to form northern subsidiary troughs in Ophir and Candor Chasmata and the Coprates/north Melas/Ius graben system. The peripheral troughs are only 2-5 km deep, shallower than the central troughs. Chaotic terrain is seen in the peripheral troughs near a common contour level of about 4 km on the adjacent plateaus, which supports the idea of release of water under artesian pressure from confined aquifers. The layered deposits in the peripheral troughs may have formed in isolated depressions that harbored lakes and predated the formation of the deep outflow channels. (If these layered deposits are of volcanic origin, they may have been emplaced beneath ice in the manner of table mountains.) Areal and volumetric computations show that erosion widened the troughs by about one-third and that deposits occupy one-sixth of the interior space. Even though the volume eroded is larger than the volume deposited, topographic and geologic considerations imply that material eroded from trough walls was probably part of the interior layered deposits but not their sole source. Additional material may have come from subterranean piping, from reworking of local disintegration products on the floors, such as chaotic materials, or from eolian influx. But overall it is likely that the additional material is volcanic and that it forms mostly the upper, more diversely bedded layers of the interior deposits.

Lucchitta, B. K.; Isbell, N. K.; Howington-Kraus, A.

1994-02-01

32

Variable features in the Valles Marineris region of Mars  

NASA Technical Reports Server (NTRS)

Transient phenomena on Mars have long been recognized in Mariner and Viking images as well as in decades of Earth based telescopic observations. These events are of interest because of the information they present on currently active meteorological and geological processes. Changes in surface albedo patterns and atmospheric conditions can also affect the analysis and interpretation of data based on spectral or morphological properties of geologic units on the surface. The mechanism responsible for albedo pattern change is currently under investigation. Generation and subsequent transportation and deposition of dark sands has been interpreted in the Valles. However, the removal of a bright dust layer is more consistent with the rapid time period of the change (about two months) and with preliminary multispectral mapping results which suggest that the dark streak south of Eos and Coprates Chasmata is spectrally distinguishable from the dark saltating materials found elsewhere in the canyon system. If a layer of bright dust was removed to affect the albedo change, questions concerning how such micron-sized particles are mobilized by the winds during a normally quiescent season (Southern Hemisphere Autumn) should be addressed.

Geissler, Paul E.; Singer, Robert B.

1991-01-01

33

The Seasonal Behavior of Water Ice Clouds in the Tharsis and Valles Marineris Regions of Mars: Mars Orbiter Camera Observations  

NASA Technical Reports Server (NTRS)

The Mars Orbiter Camera (MOC) was used to obtain global maps of the Martian surface. The maps used were acquired between March 15, 1999 (LS = 110 ) and July 31, 2001 (L(sub s) = 110), corresponding to approximately one and a quarter martian years. In this work we focused on water ice clouds associated with the surface features of Olympus Mons, Ascraeus Mons, Pavonis Mons, Arsia Mons, Alba Patera, and the Valles Marineris canyon system. Using these data, we have made three types of quantitative measurements to characterize the cloud activity: 1) cloud area and location, 2) cloud height, and 3) cloud optical depth. We have also searched for short period variations in the cloud areas.

Benson, J. L.; Bonev, B. P.; James, P. B.; Shan, K. J.; Cantor, B. A.; Caplinger, M. A.

2003-01-01

34

Geologic Analysis of a Possible Oasis and Environs in the Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

We used Mars Global Surveyor data from TES, MOC, and MOLA to examine the geologic history of a region of interior layered deposits on the floor of western Candor Chasma in the Valles Marineris, Mars. This site was characterized by Geissler et al. (1993, Icarus 106) as having an unusual reddish color in multispectral images from Viking and Phobos missions. The red color was associated with two 20-km-long depressions and was thought to indicate the presence of crystalline ferric oxides (possibly hematite) in the layered deposits. Assuming that water was required to form the iron oxides via aqueous or hydrothermal alteration, these depressions may mark the site of a local oasis involving ponding or groundwater seepage in the canyon. Thermal inertia and dust index images from TES data of west Candor Chasma indicate that mantling and obscuration of local outcrops is not significant in the region of the possible oasis. To characterize the mineralogy of this area, we use multiple-endmember spectral mixture analysis (MESMA) to deconvolve TES emissivity data relative to laboratory spectra of minerals. This method identifies the minimum number of components (4 to 5) required to model the spectrum of each pixel in the spectral ranges of 307-507 cm-1 and 825-1301 cm-1 (66 TES channels) through iterative comparisons to a 33-component mineral spectral library. This library, adapted from that of ASU, includes pyroxenes, plagioclase feldspars, clays, micas, amphiboles, sulfates, carbonates, olivines, K-spar, gray hematite, and volcanic glass, plus 5 atmospheric endmembers and a blackbody. Although nanophase red hematite is undistinguished at TES wavelengths, mineral abundance maps indicate the presence of other Fe-rich minerals (such as nontronite and Fe-smectite) at this site. Gray hematite, hi-Ca clinopyroxene, Fe-rich olivine, and hi-Ca plagioclase minerals are also observed within layered deposits in the canyon walls and interior, as well as in dark materials at the base of canyon walls. These results suggest that we are mapping sites of alteration and volcanism in west Candor Chasma with the TES data. We are currently performing photoclinometric modeling of coregistered MOC (6 m/pixel) and MOLA (500 m/pixel) data via the method of Soderblom et al. (2002, LPS\\ #1254) to evaluate the orientation and possible origin of this layered deposit.

Gaddis, L. R.; Staid, M. I.; Titus, T. N.

2002-12-01

35

HiRISE Observations of Layered Deposits In and Around Valles Marineris  

Microsoft Academic Search

The HiRISE camera on the Mars Reconnaissance Orbiter is providing spectacular images of Mars in color and at approximately 30-60 cm\\/pixel resolution. Stereo images produced by taking two images at different roll angles are also valuable for viewing topography and stratigraphy. We have used the HiRISE data to examine the light- toned layered deposits (LTLD), both inside Valles Marineris and

C. M. Weitz; A. McEwen

2007-01-01

36

The influence of the topography on landslide's mobility in Valles Marineris (Mars), by a numerical & remote sensing approach  

NASA Astrophysics Data System (ADS)

Landslides play a major role in the erosion processes and transport at the surface of the Earth and Mars. Indeed, the dynamics of the landscapes is strongly tributary of these catastrophic events which also constitute important risks for the populations on Earth. It is thus advisable to study their dynamics. In addition, water often takes part in the dynamics of these events on Earth. Former work highlights a very great mobility of the gravitational flows over Mars [1] [2] [3]. The studies of martians landslides contribute to understand the dynamics of the landscapes and also teach us about climate conditions during those events occurring at Amazonian Time [4] as the potential presence of ground water. Currently, there is no unified theory for describing the landslides at the field scale. The description of granular flows is quiet well understood at the microscopic scale using various experimental and numerical experiments. But at the macroscopic scale, description remains today a largely open and wide problem. Dry granular flows experiments on an horizontal plane [5] present several differences with martians data [7]. Runout of martians landslides are twice larger than in experiments. Numerical studies in agreement with experiments scaling laws using a numerical model developped by F. Bouchut and A. Mangeney [6] based on Saint-Venant equations is proposed. Our studies focus on the influence of the topography on landslide's mobility occuring in Valles Marineris. To start with MOLA/MGS DEM data, it is also possible to rebuild the paleotopography using remote sensing methods for identification of landslide deposits. We use HRSC/MeX, THEMIS/MO and MOC/MGS images to find out correctly each area of deposits in our DEM. Afterwards, we perfom a series of numerical experiments to model landslides over a real topography rebuilt from MOLA grid. Our results show that the topography is a main parameter which contribute significantly to increase the mobility of granular flows. Nevertheless, the taking into account of the topography does not explain the total differences between experiments and martians landslides. Our simulations show also that the mobility of martians landslides is larger than the mobility observed in dry granular flows experiments (one order of magnitude larger) [7] but still remains under sur-satured sub-marines landslides (one order of magnitude less) [8]. Those results show that it is needed to introduce another physical process to explain such mobility. The results do not allow to conclude about the role of water in the martians landslide dynamics. We propose that degazing processes causing by CO2 or sublimation of icy lenses in the ground would imply an increasing of mobility during slide events at Amazonian. A geological study using mineralogy given by OMEGA/MeX and Radar profile given by MARSIS/MeX would help to subjugate our preliminary results. References [1] B. K. Lucchitta. Landslides in Valles Marineris, Mars. Journal of Geoph. Research, 84:8097-8113, December 1979. [2] A. S. McEwen. Mobility of large rock avalanches : Evidence from Valles Marines, Mars. Geology, pages 1111-1114, 1989. [3] C. Quantin, P. Allemand, and C. Delacourt. Morphology and geometry of Valles Marineris landslides. Planetary and Space Sciences, 52:1011-1022, September 2004. [4] C. Quantin, P. Allemand, N. Mangold, and C. Delacourt. Ages of Valles Marineris (Mars) landslides and implications for canyon history. Icarus, 172:555- 572, December 2004. [5] E. Lajeunesse, A. Mangeney-Castelnau, and J. P. Vilotte. Spreading of a granular mass on a horizontal plane. Physics of Fluids, 16:2371-2381, July 2004. [6] A. Mangeney-Castelnau, F. Bouchut, J. P. Vilotte, E. Lajeunesse, A. Aubertin, and M. Pirulli. On the use of Saint Venant equations to simulate the spreading of a granular mass. Journal of Geophysical Research (Solid Earth), 110:9103- +, September 2005. [7] E. Lajeunesse, C. Quantin, P. Allemand, and C. Delacourt. New insights on the runout of large landslides in the Valles-Marineris canyons, Mars. Geophysical Research Letters, 33:4

Lucas, A.; Mangeney, A.

37

Stratigraphy and erosional landforms of layered deposits in Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

Satellite imagery is used to identify stratigraphy and erosional landforms of 13 layered deposits in the Valles Marineris region of Mars (occurring, specifically, in Gangis, Juventae, Hebes, Ophir-Candor, Melas, and Capri-Eos Chasmata), based on albedo and erosional styles. Results of stratigraphic correlations show that the stratigraphy of layered deposits in the Hebes, Juventae, and Gangis Chasmata are not well correlated, indicating that at least these chasmata had isolated depositional environments resulting in different stratigraphic sequences. On the other hand, the layered deposits in Ophir-Candor and Melas Chasmata appear to have been connected in each chasma. Some of the layered deposits display complexities which indicate changes in space and time in the dominant source materials.

Komatsu, G.; Geissler, P. E.; Strom, R. G.; Singer, R. B.

1993-06-01

38

Lithologic and Structural Control on Slope Morphology in the Valles Marineris  

NASA Technical Reports Server (NTRS)

Throughout the Valles Marineris scarp morphology varies as a function of lithology, structure and scarp height. In addition lithology is an important control on permeability and the relative importance of spring sapping processes. Geomorphic mapping of distinct subareas can be used to define the characteristic scarp forms. Distinct morphologic zones defined on the basis of regional variations in lithology are described. Lithology and tectonic history are shown to be the two most important factors controlling slope development. Regional variation in scarp morphology can be correlated with the orientation and density of fracture systems; scarp height and the presence of rejuvenated fault scarps; and the thickness and degree of exposure of presumably less competent, more permeable, water saturated crated plateau material in the chasmata scarps.

Patton, P. C.

1985-01-01

39

Correlations Between Textures and Infrared Spectra of the Martian Surface in Valles Marineris  

NASA Astrophysics Data System (ADS)

RALSTON, S. J., School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332, sralston3@gatech.edu, WRAY, James, School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332, jwray@eas.gatech.edu In the past few decades, a wealth of information has become available on the appearance and composition of the Martian surface. While some previous research has examined possible correlations between certain surface features and mineralogy (such as the hypothesized connection between Recurring Slope Lineae and perchlorate salts), little has yet been done to determine possible correlations between mineralogy and texture in less extraordinary circumstances. In this project, one hundred images taken from across the Valles Marineris region were examined both in infrared (obtained from the CRISM instrument aboard the Mars Reconnaissance Orbiter) and in visible-light images from the HiRISE camera. Spectra were obtained from regions of interest, focusing mainly on the identification of monohydrated and polyhydrated sulfates. Other materials were included in the imaging, including phyllosilicate clays, gypsum, and jarosite, although those materials proved less abundant than the sulfates. The areas from which the spectra were taken were then examined in visible-light wavelengths using HiRISE images to determine textural qualities. The focus of this research was on two particular textures, a 'reticulated' texture and a 'stepped texture,' hypothesized to correlate to monohydrated and polyhydrated sulfates, respectively. Results showed that over 55% of areas containing monohydrated sulfates also contained reticulate texture, whereas areas that contained other materials, such as polyhydrated sulfates and clays, had only a 2-8% correlation with reticulate texture. The stepped texture was shown to have no significant correlation to any one material, although other texture/mineral pairs did show some correlation. This presentation will cover the range of textures and mineralogy found throughout Valles Marineris.

Ralston, S. J.; Wray, J. J.

2013-12-01

40

Analysis of a new geomorphological inventory of landslides in Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

We completed a systematic mapping of landslides in a 105 km area in Tithonium and Ius Chasmata, Valles Marineris, Mars, where landslides are abundant. Using visual interpretation of medium to high-resolution optical images, we mapped and classified the geometry of 219 mass wasting features, including rock slides, complex/compound failures, rock avalanches, debris flows, and rock glacier-like features, for a total landslide area of ALT=4.4×104 km, 44% of the study area, a proportion larger than previously recognised. Studying the landslide inventory, we showed that the probability density of landslide area p(AL) follows a power law, with a scaling exponent ?=-1.35±0.01, significantly different from the exponents found for terrestrial landslides, ?=-2.2 and ?=-2.4. This indicates that the proportion of large landslides (AL>107 m) is larger on Mars than on Earth. We estimated the volume (VL) of a subset of 49 deep-seated slides in our study area and found that the probability density of landslide volume p(VL) obeys a power law trend typical of terrestrial rock falls and rock slides, with a slope ?=-1.03±0.01. From the combined analysis of landslide area and volume measurements, we obtained a power law dependency comparable to a similar relationship obtained for terrestrial bedrock landslides, VL=(1.2±0.8)×AL(1.25±0.03). From the fall height HL and run out length LL of a subset of 83 slides unaffected by topographic confinement, we obtained the mobility index (Heim's ratio) HL/LL, a measure of the apparent friction angle of the failed materials, ?=14.4°±0.4°. Slope stability simulations and back analyses performed adopting a Limit Equilibrium Method, and using Monte Carlo approaches on failed and stable slopes, suggest that the large landslides in Valles Marineris were seismically induced.

Brunetti, Maria Teresa; Guzzetti, Fausto; Cardinali, Mauro; Fiorucci, Federica; Santangelo, Michele; Mancinelli, Paolo; Komatsu, Goro; Borselli, Lorenzo

2014-11-01

41

MGS/TES-Odyssey/THEMIS-IR Analysis of Localized Low Albedo Regions in Valles Marineris  

NASA Technical Reports Server (NTRS)

We are conducting a systematic analysis of small (approximately 10's of km), localized regions in Valles Marineris that display significant albedo differences relative to their surroundings. This analysis is based on a finding that the locations of the hematite deposits identified by [1] in the interior layered deposits of Valles Marineris typically coincide with regions having a low MGS/TES visible bolometric albedo [1,2]. Until recently, it was difficult to identify the morphology or geologic context of the regions containing the hematite deposits. However, with the recent advent of high-resolution (1/128 /pixel) MOLA grided topography and Mars Odyssey s THEMIS-IR instrument, it has been possible to better understand the morphologic context of TES observations. This analysis combines the use of PDS-released data from the MGS/TES visible bolometer and infrared spectrometer, the Odyssey/THEMIS Infrared imager, and MOLA grided topography. First, the TES infrared bolometer is used to identify regions of interesting albedo variability, and is overlaid on Viking controlled photomosaics for context. THEMIS-IR data, in conjunction with MOLA topography, is then used to: 1) identify the context and morphology of the area; and 2) identify spectrally unique regions at the km scale. In preparation for the latter, all the THEMIS planes are coregistered using an autocorrelation routine, the data are converted to brightness temperature and then each plane is normalized to the brightness temperature of the third plane (1261 cm-1). We then perform a 3-band search for color variations and a Principle Components Analysis (PCA) of the 8 unique bands in the THEMIS-IR dataset. Any variability is then investigated using both THEMIS-IR and TES spectra of the same regions. In both cases, the spectra are ratioed to near-simultaneously acquired spectra of adjacent or "average" regions that do not show this albedo variation, therefore allowing us to identify spectral variability unique to the area of interest. This procedure also allows us to account for calibration problems in THEMIS-IR data, and for any atmospheric effects in both the THEMIS-IR and the TES data.

NoeDobrea, E. Z.; Bell, J. F., III; Wolff, M. J.; Snook, K. J.

2003-01-01

42

Erosional development of bedrock spur and gully topography in the Valles Marineris, Mars  

NASA Technical Reports Server (NTRS)

Gully networks separated by resistant bedrock spurs are a common erosional feature along the escarpments that border the Valles Marineris. The resistant spur topography is best developed where the base of the slope is truncated by linear scarps interpreted as fault scarps. Regional variations in slope morphology imply that spur and gully topography undergoes a systematic progressive degradation through time associated with the erosional destruction of the basal fault scarps. The comparative morphometry of the divide networks indicates that the density of the spur networks and the number of first-order unbranched spurs decreases as the basal slope break becomes more sinuous. Abstraction of the spurs occurs through regolith storage in adjacent gullies at the slope base and the most degraded slope forms are entirely buried in talus. The basal fault scarps apparently control regolith transport by allowing debris to drain from the slope. As these basal scarps decay the slope base becomes increasingly sinuous and the slopes become transport limited. Dry mass-wasting may be the most important process acting on these slopes where a continually lowered base level is required to maintain the spur topography. In contrast to the Martian slopes, range front fault escarpments in the western U.S. show no systematic trend in spur network geometry as they are eroded. These weathering limited slopes are controlled by the more efficient removal of regolith through fluvial processes which rapidly create quasi-equilibrium drainage networks.

Patton, Peter C.

1990-01-01

43

Structural development of Coprates Chasma and western Ophir Planum, Valles Marineris Rift, Mars  

NASA Technical Reports Server (NTRS)

A portion of Valles Marineris was mapped in detail in order to clarify the dominant processes responsible for the formation of Coprates Chasma. New crater counts indicate that the caprock on western Ophir Planum plateau has a Late Hesperian crater age, whereas trough floor preserved in western Coprates Chasma has an Early to Late Hesperian crater age. Caprock on western Ophir Planum correlates in relative age with the Syria Planum Formation, and the caprock may overlie Lower Hesperian ridged plains material. Trough floor material in Coprates Chasma correlates in relative age with ridged plains material on the adjacent Lunae Planum and Coprates plateaus and represents a structurally coherent block displaced downward by normal faulting. The crater counts and detailed structural relationships demonstrate the commonly accepted view that Coprates Chasma occupies a graben. Formation of Coprates Chasma by keystone collapse of locally elevated topography is not supported by available topographic data, but a general association between the trough and volcanotectonic activity in the Tharsis region is considered to be a likely explanation for the trough forming stresses. Faulting on Ophir Planum appears related to the faulting that created the Coprates Chasma trough. The geology and structure of Coprates Chasma are comparable to those of other troughs such as Melas, Ius, and perhaps Candor chasmata, suggesting that these troughs may also have formed as grabens.

Schultz, Richard A.

1991-01-01

44

Structural development of Coprates Chasma and western Ophir Planum, Valles Marineris Rift, Mars  

NASA Astrophysics Data System (ADS)

A portion of Valles Marineris was mapped in detail in order to clarify the dominant processes responsible for the formation of Coprates Chasma. New crater counts indicate that the caprock on western Ophir Planum plateau has a Late Hesperian crater age, whereas trough floor preserved in western Coprates Chasma has an Early to Late Hesperian crater age. Caprock on western Ophir Planum correlates in relative age with the Syria Planum Formation, and the caprock may overlie Lower Hesperian ridged plains material. Trough floor material in Coprates Chasma correlates in relative age with ridged plains material on the adjacent Lunae Planum and Coprates plateaus and represents a structurally coherent block displaced downward by normal faulting. The crater counts and detailed structural relationships demonstrate the commonly accepted view that Coprates Chasma occupies a graben. Formation of Coprates Chasma by keystone collapse of locally elevated topography is not supported by available topographic data, but a general association between the trough and volcanotectonic activity in the Tharsis region is considered to be a likely explanation for the trough forming stresses. Faulting on Ophir Planum appears related to the faulting that created the Coprates Chasma trough. The geology and structure of Coprates Chasma are comparable to those of other troughs such as Melas, Ius, and perhaps Candor chasmata, suggesting that these troughs may also have formed as grabens.

Schultz, Richard A.

1991-12-01

45

Numerical slope stability simulations of chasma walls in Valles Marineris/Mars using a distinct element method (dem).  

NASA Astrophysics Data System (ADS)

NUMERICAL SLOPE STABILITY SIMULATIONS OF CHASMA WALLS IN VALLES MARINERIS/MARS USING A DISTINCT ELEMENT METHOD (DEM). B. Imre (1) (1) German Aerospace Center, Berlin Adlershof, bernd.imre@gmx.net The 8- to 10-km depths of Valles Marineris (VM) offer excellent views into the upper Martian crust. Layering, fracturing, lithology, stratigraphy and the content of volatiles have influenced the evolution of the Valles Marineris wallslopes. But these parameters also reflect the development of VM and its wall slopes. The scope of this work is to gain understanding in these parameters by back-simulating the development of wall slopes. For that purpose, the two dimensional Particle Flow Code PFC2D has been chosen (ITASCA, version 2.00-103). PFC2D is a distinct element code for numerical modelling of movements and interactions of assemblies of arbitrarily sized circular particles. Particles may be bonded together to represent a solid material. Movements of particles are unlimited. That is of importance because results of open systems with numerous unknown variables are non-unique and therefore highly path dependent. This DEM allows the simulation of whole development paths of VM walls what makes confirmation of the model more complete (e.g. Oreskes et al., Science 263, 1994). To reduce the number of unknown variables a proper (that means as simple as possible) field-site had to be selected. The northern wall of eastern Candor Chasma has been chosen. This wall is up to 8-km high and represents a significant outcrop of the upper Martian crust. It is quite uncomplex, well-aligned and of simple morphology. Currently the work on the model is at the stage of performing the parameter study. Results will be presented via poster by the EGS-Meeting.

Imre, B.

2003-04-01

46

THE FORMATION OF VALLES MARINERIS, MARS. J. C. Andrews-Hanna, Department of Geophysics, Colorado School of Mines, Golden, CO, jcahanna@mines.edu.  

E-print Network

THE FORMATION OF VALLES MARINERIS, MARS. J. C. Andrews-Hanna, Department of Geophysics, Colorado tectonic feature on Mars, consisting of troughs up to 2000 km in length, 200 km in width, and 10 km. Figure 1. Present-day topography and isostatic roots of Mars in a polar projection centered around

47

Cross faults in extensional settings: Stress triggering, displacement localization, and implications for the origin of blunt troughs at Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

Motivated by conflicting interpretations concerning the origin of blunt terminations of troughs at Valles Marineris, Mars, we investigate the reactivation of preexisting cross faults in response to stress changes associated with slippage along a major, basin-bounding normal fault (i.e., border fault). Coulomb stress changes indicate that cross fault reactivation is possible in both the footwalls and hanging walls of border faults, although this is dependent on the distance between the border and cross faults. Cross faults accommodate dip-slip normal motion for most border fault geometries and conditions we tested, but strike-slip motions are predicted when preexisting cross faults are vertical. Furthermore, although lateral extensions of the border fault (LEBFs) may nucleate within cross fault footwalls at all stages of border fault development, they are favored to develop when border faults and cross fault tip lines are proximal. Observations from the Valles Marineris extensional province, Mars, are consistent with (1) normal displacements along cross faults, (2) numerous examples of pit-chains, interpreted to represent surface expressions of lateral extensions to the border fault (LEBF), (3) the lack of well-developed cross faults in the footwall of border faults, and (4) the inference that tapered trough ends formed in areas that lacked cross faults prior to the main phase of extension at Valles Marineris. We suggest a new sequence of deformation that accounts for the formation of blunt-trough terminations during the major phase of Valles Marineris extension: coeval and locally bidirectional extension, that results from local stress field changes associated with border fault growth in a dominantly unidirectional remote (extensional) strain field. By implication, many of the irregular closed troughs such as Hebes Chasma are better interpreted as grabens rather than collapse depressions.

Wilkins, Scott J.; Schultz, Richard A.

2003-06-01

48

Morphology, composition, age and spatial extent of a layered superficial formation covering the plains around Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

Introduction An extensive light-toned layered formation covers the plains surrounding Valles Marineris on Mars. It is particularly visible south of Ius Chasma and of Melas Chasma [1], southwest of Juventae Chasma [2,3], north of Tithonium Chasma and west of Ganges Chasma. Some deposits of this formation may be enriched in hydrated silicates such as hydrated glasses, chalcedony, opal or other hydrated Si-rich phases according to CRISM data [1]. From an analysis of HRSC, THEMIS, MOC, HiRISE, MOLA PEDR, OMEGA and CRISM data, we discuss the morphology, the composition, the age, the spatial extent and the emplacement processes of these layered deposits (LDs). Here we focus on two regions where the LDs are particularly spectacular: Ganges Chasma and Juventae Chasma. Regional map We have compiled a regional map of the LDs around Valles Marineris (orange in Fig. 1a). In some cases their spatial extent is unclear due to their being covered either by dark material or by dust that appears yellow on IRB color HiRISE images (Fig 1b). Dashed contours on Fig. 1a outline these poorly constrained boundaries, whereas plain contours correspond to regions where the stratigraphic contact between the LDs and the underlying basement is unambiguous. The light-toned LDs are located stratigraphically and topographically above the basaltic basement that constitutes the plains surrounding Valles Marineris. The total thickness of the LDs does not exceed a hundred meters on average. They consist of subparallel light-toned layers of various thicknesses that are apparently interbedded with darker beds (Fig. 1b). This difference in albedo can be due to variations in mineralogical composition, topographic slope, roughness, grain size or state of erosion of the different layers, or to partial covering of certain layers by a dark mantle. Ganges Chasma West of Ganges Chasma, the LDs rest topographically and stratigraphically above the Noachian plains that have been defined as the Npl2 unit [4] (Fig. 1c). Npl2 has been interpreted as thin interbedded lava flows and eolian deposits that partly bury underlying rocks [4]. Outcrops of bright material on CTX and night-time infrared THEMIS images are exposed a few tens of kilometres west of the LDs. These light-toned outcrops are located near the Hesperian outflow channel Allegheny Vallis [5] (Fig. 1c). They may correspond to exposures of the Npl2 unit or alternatively to a formation covering Npl2. The LDs are located stratigraphically above the outflow channel, so they are Hesperian in age or younger. LDs are characterized by a particularly low brightness temperature on night-time THEMIS images in comparison with the surrounding plains (Fig. 1d). It suggests that the LDs are composed of a soft material that is sensitive to erosion. This is consistent with the occurrence of remnant buttes, kilometres away from the largest outcrop. The buttes attest that the LDs were more extensive in the past and have been removed by erosion in many places. The thickness of the LDs ranges from 10 to 40 m on average. Their constitutive layers are subparallel to each other but they locally exhibit deformation features such as folds and fractures. Some layers display a polygonal texture. The polygons range from a few metres to about 10 m in diameter. This polygonal network may be due to thermal contraction, desiccation or sublimation [6]. Sinuous ridges, as wide as 60 m, are visible on the LDs (Fig. 1c). At night, they have a similar brightness temperature as the LDs and they are apparently composed of the same material. Their morphology suggests that they are eskers or inverted fluvial channels [7-9]. In that latter case, a fluvial origin could explain the deposition of the LDs. However, other origins such as lacustrine or glacial deposition, ash or dust air-fall and ash flows cannot be excluded. The analysis of CRISM data (FRT 8949) shows that some layers have spectral characteristics of hydrated materials. Ratio spectra display small absorption bands at ~1.39 ?m and ~1.92 ?m, a deep band centred near ~2.2-2.24 ?m, and a drop be

Le Deit, L.; Bourgeois, O.; Le Mouélic, S.; Quantin-Nataf, C.; Mège, D.; Sotin, C.; Massé, M.; Sarago, V.

2008-09-01

49

Valles Marineris dune fields as compared with other martian populations: Diversity of dune compositions, morphologies, and thermophysical properties  

NASA Astrophysics Data System (ADS)

Planetary dune field properties and their bulk bedform morphologies relate to regional wind patterns, sediment supply, climate, and topography. On Mars, major occurrences of spatially contiguous low-albedo sand dunes are primarily found in three major topographic settings: impact craters, high-latitude basins, and linear troughs or valleys, the largest being the Valles Marineris (VM) rift system. As one of the primary present day martian sediment sinks, VM holds nearly a third of the non-polar dune area on Mars. Moreover, VM differs from other regions due to its unusual geologic, topographic, and atmospheric setting. Herein, we test the overarching hypothesis that VM dune fields are compositionally, morphologically, and thermophysically distinct from other low- and mid-latitude (50°N-50°S latitude) dune fields. Topographic measurements of dune fields and their underlying terrains indicate slopes, roughnesses, and reliefs to be notably greater for those in VM. Variable VM dune morphologies are shown with topographically-related duneforms (climbing, falling, and echo dunes) located among spur-and-gully wall, landslide, and chaotic terrains, contrasting most martian dunes found in more topographically benign locations (e.g., craters, basins). VM dune fields superposed on Late Amazonian landslides are constrained to have formed and/or migrated over >10s of kilometers in the last 50 My to 1 Gy. Diversity of detected dune sand compositions, including unaltered ultramafic minerals and glasses (e.g., high and low-calcium pyroxene, olivine, Fe-bearing glass), and alteration products (hydrated sulfates, weathered Fe-bearing glass), is more pronounced in VM. Observations show heterogeneous sand compositions exist at the regional-, basinal-, dune field-, and dune-scales. Although not substantially greater than elsewhere, unambiguous evidence for recent dune activity in VM is indicated from pairs of high-resolution images that include: dune deflation, dune migration, slip face modification (e.g., alcoves), and ripple modification or migration, at varying scales (10s-100s m2). We conclude that VM dune fields are qualitatively and quantitatively distinct from other low- and mid-latitude dune fields, most readily attributable to the rift's unusual setting. Moreover, results imply dune field properties and aeolian processes on Mars can be largely influenced by regional environment, which may have their own distinctive set of boundary conditions, rather than a globally homogenous collection of aeolian sediment and bedforms.

Chojnacki, Matthew; Burr, Devon M.; Moersch, Jeffrey E.

2014-02-01

50

Coordinating CRISM Observations of Sulfates near Valles Marineris with the Subsurface Bright Salty Soils Exposed in Gusev Crater via Lab Experiments  

NASA Astrophysics Data System (ADS)

CRISM has identified unique spectral signatures in inverted channels near Juventae Chasma and other chasmata in the greater Valles Marineris region [1] that are composed of light-toned layered sediments interpreted to be fluvial in origin [2]. These include a weak, broad feature near 1.45 ?m, a strong, broad band centered near 1.94 ?m, a sharp band at 2.23 ?m, and a shoulder or band near 2.4 ?m [3]. This signature is not characteristic of any single mineral; however, it is consistent with partially dehydrated ferricopiapite [original formula of Fe0.33Fe2(SO4)3(OH)·10H2O]. Our lab experiments show that incrementally heating this hydrated ferric sulfate to 300 °C at 1 atm changes the color, XRD pattern, and spectral properties of this mineral. The resulting spectral signature of our ferricopiapite heated to 300 °C matches well with the CRISM spectra of the material observed in inverted channels near Juventae Chasma. This result is of particular interest as ferricopiapite is the mineral thought to be present in the bright salty soils exposed by the Spirit rover at Paso Robles and other sites in combined analyses of the Pancam, Mössbauer, Mini-TES and APXS data [4, 5, 6]. Other sulfate minerals possibly present in lower abundance include butlerite, (para)coquimbite, fibroferrite, and metahohmanite [4]. Continued lab experiments are underway to characterize the spectral properties of partially dehydrated ferricopiapite and other OH and H2O-bearing sulfates. Opaline silica is also found in these inverted channels near Juventae Chasma [1] and both monohydrated (szomolnokite and kieserite) and polyhydrated (e.g. ferricopiapite) sulfates are observed in the bright mounds inside the chasma [7]. Identification of partially dehydrated ferricopiapite in these inverted channels provides a link between the aqueous processes occurring in the plains outside the chasma and those processes that formed the light-toned layered mounds inside the chasma. Sulfate deposits in the greater Valles Marineris region are consistent with lithification and diagenetic modification of eolian sediments by evaporation of near-surface groundwater [8], processes similar to those inferred at Meridiani [9,10]. [1] Milliken R. E. et al. (2008) Geology, in press. [2] Weitz C. M. et al. (2008) GRL, doi:10.1029/2008GL035317, in press. [3] Bishop J. L. et al. (2008) JGR, to be submitted. [4] Lane M. D. et al. (2008) Am. Miner., 93, 728-739. [5] Parente M. et al. (2008) Icarus, in review. [6] Johnson J. R. et al. (2007) GRL, 34, L13202, doi:10.1029/2007GL029894. [7] Bishop J. L. et al. (2008) LPSC, abs. 2334. [8] Murchie S. L. et al. (2008) Nature, in revision. [9] Squyres S. W. et al. (2006) Science, 313, 1403- 1407. [10] Andrews-Hanna J. C. et al. (2007) Nature, 446, 163-166 doi:10.1038/nature05594.

Bishop, J. L.; Parente, M.; Lane, M.; Dyar, M. D.; Bish, D. L.; Sarrazin, P.; King, P.; McKeown, N.; Milliken, R.; Roach, L.; Swayze, G.; Weitz, C.; Murchie, S.; Mustard, J. F.

2008-12-01

51

The Grand Canyon of Mars and how it formed  

NSDL National Science Digital Library

This module from the Mars Exploration Curriculum revolves around the formation of Valles Marineris. Students investigate the formation of Mars' 3,000 mile-long rift valley. After investigating how a planet's surface can be altered and analyzing data and images from NASA's missions to Mars, students develop hypotheses to explain the rift valley's formation and amass evidence to support their ideas.

52

Hubble's Look at Mars Shows Canyon Dust Storm, Cloudy Conditions for Pathfinder Landing  

NASA Technical Reports Server (NTRS)

Hubble Space Telescope images of Mars, taken on June 27, 1997, reveal a significant dust storm which fills much of the Valles Marineris canyon system and extends into Xanthe Terra, about 600 miles (1000 kilometers) south of the landing site.

It is difficult to predict the evolution of this storm and whether it will affect the Pathfinder observations.

The pictures were taken in order to monitor the site in Ares Vallis where the Pathfinder spacecraft will land on July 4.

The two images of Mars at the top of the figure are Hubble observations from June 27 (right) and May 17 (left). Visual comparison of these two images clearly shows the dust storm between 5 and 7 o'clock and about 2/3 of the way from the center of the planet's disk to the southern edge of the June image.

The digital data were projected to form the map of the equatorial portion of the planet which is shown in the bottom portion of the figure. The green cross marks the location of the Pathfinder landing site, and the yellowish ribbon of dust which runs horizontally across the bottom of the map traces the location of Valles Marineris, a system of canyons which would stretch from Los Angeles to New York if placed on Earth.

Most of the dust is confined within the canyons, which are up to 5-8 kilometers deep. The thickness of the dust cloud near the eastern end of the storm is similar to that observed by Viking lander 1 during the first of the two 1977 global dust storms which it studied.

Other interesting features appear in this image. The northwestern portions of the planet are enveloped in unusually thick water ice clouds, similar to cirrus clouds on Earth; some clouds extend as far as Lunae Planum, the slightly darker region about halfway from the center to the left side of the map. The dark spot near the terminator (boundary between day and night) at about 9:00 in the June 27 planet image is Ascraeus Mons, a 27 kilometer high volcano, protruding through the clouds.

The remnant north polar cap, composed of water ice, is at the top of the May and June images, and a bluish south polar hood, composed of water ice clouds, is seen along the southern edge. Because the planet's axis is tipped towards us during this season, we cannot see the south polar cap, which is in winter darkness.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

1997-01-01

53

Hot Canyon  

SciTech Connect

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."

None

2012-06-18

54

Hot Canyon  

SciTech Connect

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."

None

2012-01-01

55

Hebrus Valles  

NASA Technical Reports Server (NTRS)

(Released 3 June 2002) The Science Hebrus Valles is located in the Elysium Planitia region of the northern lowlands of the planet. This image shows three sinuous tributaries of the channel system which carved up the surrounding plains. These individual tributaries are up to 3 km wide and have up to three terraces visible along their margins. These terraces may indicate separate flood events or may be the result of one flood plucking away at channel wall materials with varying strengths of resistance. It is not clear if these are separate rock layers or just the erosion of one type of material from rising and falling water levels. A streamlined island is visible in the lower third of the image. This feature indicates that flow was from the lower right to upper left in this region (the tail of the island points downstream). In places ripples, interpreted to be dunes, can also be seen along the interface of the channel floor with the walls. Smaller, fainter channels can also be seen scouring the plains, especially in the lower portion of this image. Other features of note in this image are the various inselbergs (isolated hills) located primarily in the upper portion of the image. The inselbergs are surrounded with aprons of material that was probably shed off of the hills by various processes of erosion. The Story Mars was once the scene of some major floods that rushed out upon the land, carving all kinds of channels. These signs of ancient flooding have always been exciting to scientists who want to understand the history of water on the planet. Water is important to understanding the climate and geological history of Mars, as well as whether life could ever have developed there. While we can't tell much about the life question from pictures like this one, it does give some insights into the great flood itself. You can see three tributaries of a channel system that are up to two miles wide or so. The really interesting thing is that you can see terraces of land that step down from the sides of the tributaries. How did they form? Was there one massive flood that swept through, eroding materials with varying strengths of resistance? Or was it several, separate floods? And what could the answer tell us about the types of rocks and materials in this region? No one knows if these are separate rock layers or just one type of material that has eroded from rising and falling water levels. While these questions will continue to intrigue geologists, one thing that they can tell for sure is the direction the water flowed. Can you find the tear-drop shaped island in the now dry channel? On Earth, we see these islands created in rivers all the time. The 'tail' of the island (the point on the teardrop) points downstream, so that means the flood rushed down the channel from the lower right to the upper left. Since the flood, there is some rippling evidence on the channel floor that dunes may have formed. Smaller, fainter channels can also be seen scouring the plains, especially in the lower portion of this image. Other interesting features in this image are the various inselbergs (isolated hills) located primarily in the upper portion of the image. The inselbergs are surrounded with aprons of material that was probably shed off of the hills by various processes of erosion.

2002-01-01

56

The Valles natural analogue project  

SciTech Connect

The contact between an obsidian flow and a steep-walled tuff canyon was examined as an analogue for a highlevel waste repository. The analogue site is located in the Valles Caldera in New Mexico, where a massive obsidian flow filled a paleocanyon in the Battleship Rock tuff. The obsidian flow provided a heat source, analogous to waste panels or an igneous intrusion in a repository, and caused evaporation and migration of water. The tuff and obsidian samples were analyzed for major and trace elements and mineralogy by INAA, XRF, X-ray diffraction; and scanning electron microscopy and electron microprobe. Samples were also analyzed for D/H and {sup 39}Ar/{sup 4O} isotopic composition. Overall,the effects of the heating event seem to have been slight and limited to the tuff nearest the contact. There is some evidence of devitrification and migration of volatiles in the tuff within 10 meters of the contact, but variations in major and trace element chemistry are small and difficult to distinguish from the natural (pre-heating) variability of the rocks.

Stockman, H.; Krumhansl, J.; Ho, C. [Sandia National Labs., Albuquerque, NM (United States); McConnell, V. [Alaska Univ., Fairbanks, AK (United States). Geophysical Inst.

1994-12-01

57

Seismic expression of Late Quaternary Banda submarine canyon and fan offshore northern Baja California  

SciTech Connect

High-resolution seismic reflection profiles obtained throughout the inner California continental borderland offshore northwestern Baja California, Mexico, show the presence of numerous modern submarine canyons and associated fans. One set of these, the Banda submarine canyon/fan, is of relatively recent origin, as demonstrated by onlap of the basal fan sediments against an acoustically transparent, presumably hemipelagic deposit. Late Quaternary sedimentation rates inferred from isotopically dated piston core samples place the age of the postulated hemipelagic unit at approximately 650,000 years ago. The Banda submarine canyon heads within the Bahia Todos Santo and passes through a narrow gorge between Punta Banda and Islas Todos Santos. It is proposed that this submarine canyon and fan system formed entirely during late Quaternary time, following the breach of the Punta Banda ridge during a late Pleistocene high sea level stand. The presence of an ancient, buried channel exiting to the north out of Bahia Todos Santos probably marks the head of an earlier submarine canyon which acted as the conduit of clastic sediments from Valle Maneadero to the deep borderland basins. The now active Banda submarine canyon pirated the supply of terrigenous clastics from this older canyon. The active Agua Blanca fault zone cuts across the head of Banda submarine canyon, suggesting that tectonic movements may have played a role in the development of the Banda submarine canyon and fan system.

Legg, M.R.

1987-05-01

58

Flow in bedrock canyons.  

PubMed

Bedrock erosion in rivers sets the pace of landscape evolution, influences the evolution of orogens and determines the size, shape and relief of mountains. A variety of models link fluid flow and sediment transport processes to bedrock incision in canyons. The model components that represent sediment transport processes are increasingly well developed. In contrast, the model components being used to represent fluid flow are largely untested because there are no observations of the flow structure in bedrock canyons. Here we present a 524-kilometre, continuous centreline, acoustic Doppler current profiler survey of the Fraser Canyon in western Canada, which includes 42 individual bedrock canyons. Our observations of three-dimensional flow structure reveal that, as water enters the canyons, a high-velocity core follows the bed surface, causing a velocity inversion (high velocities near the bed and low velocities at the surface). The plunging water then upwells along the canyon walls, resulting in counter-rotating, along-stream coherent flow structures that diverge near the bed. The resulting flow structure promotes deep scour in the bedrock channel floor and undercutting of the canyon walls. This provides a mechanism for channel widening and ensures that the base of the walls is swept clear of the debris that is often deposited there, keeping the walls nearly vertical. These observations reveal that the flow structure in bedrock canyons is more complex than assumed in the models presently used. Fluid flow models that capture the essence of the three-dimensional flow field, using simple phenomenological rules that are computationally tractable, are required to capture the dynamic coupling between flow, bedrock erosion and solid-Earth dynamics. PMID:25254474

Venditti, Jeremy G; Rennie, Colin D; Bomhof, James; Bradley, Ryan W; Little, Malcolm; Church, Michael

2014-09-25

59

Central Valles Marineris: uncontrolled Mars Global Surveyor (MGS) Mars Orbital Camera (MOC) digital context photomosaic (250 megapixel resolution)  

USGS Publications Warehouse

These images were processed from a raw format using Integrated Software for Images and Spectrometers (ISIS) to perform radiometric corrections and projection. All the images were projected in sinusoidal using a center longitude of 70 degrees. There are two versions of the mosaic, one unfiltered (vallesmos.tif), and one produced with all images processed through a box filter with an averaged pixel tone of 7.699 (vallesmosflt.tif). Both mosaics are ArcView-ArcInfo ready in TIF format with associated world files (*.tfw).

Noreen, Eric

2000-01-01

60

Kasei Valles Flow  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-503, 4 October 2003

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows the lobate fronts of a large flow or series of smaller flow features in Kasei Valles. The rubbly surface of the flow has been interpreted to suggest that this might have been a mud flow, rather than a lava flow, but final determination will someday require a person to visit this landform 'in the field.' This picture is illuminated from the right and covers an area approximately 8 km (5 miles) wide near 15.7oN, 77.7oW.

2003-01-01

61

18. VIEW OF A CANYON IN THE CLEANUP PHASE. CANYONS ...  

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

18. VIEW OF A CANYON IN THE CLEANUP PHASE. CANYONS WERE PROCESSING ROOMS USED TO HOUSE PLUTONIUM HANDLING OPERATIONS THAT WERE NOT CONTAINED WITHIN GLOVE BOXES. CANYONS WERE DESIGNED TO BECOME CONTAMINATED. (5/10/88) - Rocky Flats Plant, Plutonium Recovery Facility, Northwest portion of Rocky Flats Plant, Golden, Jefferson County, CO

62

Hudson River Canyon GRADE LEVEL  

E-print Network

1 FOCUS Hudson River Canyon GRADE LEVEL 7-8 FOCUS QUESTION What are the effects of long activities at the DWD-106 mile site in the Hudson River Canyon. ADAPTATIONS FOR DEAF STUDENTS Teaching time in the Dumps #12;2 Deep East 2001 ­ Grades 7-8 Focus: Hudson River Canyon oceanexplorer.noaa.gov sites

63

Grand Canyon Explorer  

NSDL National Science Digital Library

Maintained by Bob Ribokas, Grand Canyon Explorer is quite extraordinary for a unaffiliated Web site. Updated regularly, it contains everything from stunning photography and geologic descriptions to information about hiking permits and park trials for users planning a trip. A highlight of the site is the guided tour, which provides descriptions and pictures from the park entrance to the Grand Canyon's spectacular formations like Mohave Point on the South Rim. The author has even provided a downloadable version of the Web site for Pocket PC's and PDA's, enabling users to have all the information at their finger tips when visiting the park.

1994-01-01

64

Black Canyon Outreach Education  

NSDL National Science Digital Library

This portal features links to K-12 outreach education units on the Black Canyon of the Gunnison National Park and Curecanti National Recreation Area. They focus on topics such as trees, habitats, fossils, animal adaptations, seasons, weather, the water cycle, mapping and geology. There are also downloadable activities for sutdents to perform either before or after their visits to the area.

65

Currents in Monterey Submarine Canyon  

Microsoft Academic Search

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

J. P. Xu; Marlene A. Noble

2009-01-01

66

Canyon in DCS Color  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released July 26, 2004 This image shows two representations of the same infra-red image covering a portion of Ganges Chasma. On the left is a grayscale image showing surface temperature, and on the right is a false-color composite made from 3 individual THEMIS bands. The false-color image is colorized using a technique called decorrelation stretch (DCS), which emphasizes the spectral differences between the bands to highlight compositional variations.

The northern canyon at the top of this image is dominated by a bright red/magenta area consisting primarly basaltic materials on the floor of the canyon and atmospheric dust. Within that area, there are patches of purple, on the walls and in the landslides, that may be due to an olivine rich mineral layer. In the middle of the image, the green on the mesa between the two canyons is from a layer of dust. The patchy blue areas in the southern canyon are likely due to water ice clouds.

Image information: IR instrument. Latitude -6.6, Longitude 316 East (44 West). 100 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

67

The Grand Canyon  

NASA Technical Reports Server (NTRS)

Northern Arizona and the Grand Canyon are captured in this pair of MISR images from December 31, 2000 (Terra orbit 5525). The left-hand image is a true color view from the nadir (vertical) camera. The right-hand image is a stereo composite generated using data from MISR's vertical and 46-degree-forward cameras. Viewing the stereo image in 3-D requires the use of red/blue glasses with the red filter placed over your left eye. To facilitate stereo viewing, the images have been oriented with north at the left.

In addition to the Grand Canyon itself, which is visible in the western (lower)half of the images, other landmarks include Lake Powell, on the left, and Humphreys Peak and Sunset Crater National Monument on the right. Meteor Crater appears as a small dark depression with a brighter rim, and is just visible along the upper right-hand edge. Can you find it?

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

2001-01-01

68

Grand Canyon Explorer: The Geology of the Grand Canyon  

NSDL National Science Digital Library

This site provides an overview of how the Grand Canyon was formed. Concepts discussed include erosion by water, ice and wind, continental drift, and deposition. A photo gallery and stratigraphic figures support the text.

Ribokas, Bob

69

New York Canyon Stimulation  

SciTech Connect

The New York Canyon Stimulation Project was to demonstrate the commercial application of Enhanced Geothermal System techniques in Buena Vista Valley area of Pershing County, Nevada. From October 2009 to early 2012, TGP Development Company aggressively implemented Phase I of Pre-Stimulation and Site/Wellbore readiness. This included: geological studies; water studies and analyses and procurement of initial permits for drilling. Oversubscription of water rights and lack of water needed for implementation of EGS were identified and remained primary obstacles. Despite extended efforts to find alternative solutions, the water supply circumstances could not be overcome and led TGP to determine a "����No Go"��� decision and initiate project termination in April 2012.

Raemy, B. Principal Investigator, TGP Development Company, LLC

2012-06-21

70

Anatomy of La Jolla Canyon  

Microsoft Academic Search

High-resolution multibeam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m) and chirp sub-bottom profiler data collected with an autonomous underwater vehicle (AUV) reveal the fine-scale morphology of La Jolla Canyon, offshore southern California. The AUV was pre-programmed to fly three missions within the canyon while maintaining an altitude of 50 m above bottom in water depths

C. K. Paull; D. W. Caress; W. Ussler; E. Lundsten; M. L. McGann; J. E. Conrad; B. D. Edwards; J. A. Covault

2010-01-01

71

78 FR 7810 - Glen Canyon Dam Adaptive Management Work Group  

Federal Register 2010, 2011, 2012, 2013

...Canyon Dam, consistent with the Grand Canyon Protection Act. The AMWG meets...consultation requirements of the Grand Canyon Protection Act (Pub. L. 102-575...technical work group (TWG), a Grand Canyon Monitoring and Research...

2013-02-04

72

Red Canyon Terrace Project  

NSDL National Science Digital Library

We know that glacial cycles produce changes in stream regimens downstream from the active ice margin, and that successive glacial cycles often result in separate (and usually lower) floodplains that become terraces following each cycle of stream incision. Using a suite of 4-5 glacio-fluvial terraces outside the mouth of Little PopoAgie Canyon on the east flank of Wyoming's Wind River Range, students do the following: (1) produce a map of the major terrace landforms, (2) observe the geomorphic characteristics of each map unit (this includes height above present stream, depth of fine overbank material above coarse bedload, and general weathering characteristics of the units, and whether the unit is a cut or fill terrace), and (3) measure the characteristics of soil profiles dug into each unit (including horizons Id's, depth and thickness of horizons, and carbonate morphology). Students use all this information to place the terrace units into the regional glacio-fluvial chronology by matching the relative age-data with the Pinedale/Bull Lake/Pre-Bull Lake regional sequence. Final project must include a graphic representation of stream heights that fit their interpretations of the regional glacio-fluvial stratigraphy.

Dahms, Dennis

73

DEVIL CANYON-BEAR CANYON PRIMITIVE AREA, CALIFORNIA.  

USGS Publications Warehouse

The Devil Canyon-Bear Canyon Primitive Area, located about 10 mi northeast of Pasadena in the Angeles National Forest, Los Angeles County, California, is an area about 8 mi long by 6 mi wide. To evaluate the mineral-resource potential of the area, geologic examinations were made by foot traverses. Samples of fresh, altered, and mineralized rocks, of sand, gravel, and other sediments, and of some panned concentrates from stream sediments were collected and analyzed. The mineral-resource survey concluded that there is little promise for the occurrence of metallic resources.

Crowder, Dwight F.; Fillo, Paul V.

1984-01-01

74

Creationism in the Grand Canyon, Texas Textbooks  

Microsoft Academic Search

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

Peter Folger

2004-01-01

75

Holden Crater/Uzboi Valles  

NASA Technical Reports Server (NTRS)

(Released 17 April 2002) The Science This image, located near 27.0S and 35.5W (324.5E), displays the intersection of Holden Crater with Uzboi Valles. This region of Mars contains a number of features that could be related to liquid water on the surface in the Martian past. Holden Crater contains finely layered sedimentary units that have been subsequently dissected. The hummucky terrain in the bottom half of the image is the remnants of this terrain, though the fine layers are not visible in this image at this resolution. The sedimentary units could have formed through deposition of material in a lacustrine type environment. Alternately, these layers could also be volcanic ash deposits. Uzboi Valles, which enters the crater from the southwest, is a catastrophic outflow channel that formed in the Martian past. The streamlined nature of the topographic features at the intersection of the crater with Uzboi Valles record the erosional pattern of flowing liquid water on the surface of Mars during the episodic outflow event. The Story Mars doesn't have a shortage of rugged terrain, and this area is no exception. While things look pretty quiet now, this cratered region was once the scene of some tremendous action. Long ago in Martian history, an incoming meteoroid probably smashed into the planet and produced a giant impact crater named Holden Crater, which stretches 88 miles across the Martian surface. The history of the area around Holden Crater doesn?t stop there. At some point, a catastrophic flood burst forth on the surface, forming an impressive outflow channel called Uzboi Valles. No one knows exactly how that happened, or whether the water might even have rushed into Holden Crater at some point, forming a long-ago lake. What we do know is that there is a lot of sedimentary material that could have formed in two hypothesized ways: in an ancient lake environment or as volcanic-ash deposits. Scientists are searching for the answers by studying the region where Uzboi Valles meets the crater. You can see the rough edge of Holden Crater running diagonally down in a sharply edged swath (from the top left-hand corner of this image to the center right-hand side). Just below it, running almost smoothly down the right-hand side of the image is an intriguing channel where water may once have flowed. Much of the terrain in the bottom half of the image, in fact, seems to be cut into a swish-swash of dissected sedimentary terrain. Sliced through in such a way, the terrain ends up carrying bunches of small, rounded hills called 'hummocks.' Earth can boast of its own rolling, hummocky terrain too, such as that found in the ravine-cut Missouri Hills and High Plains areas of South Dakota.

2002-01-01

76

Thomas Moran: "The Grand Canyon."  

ERIC Educational Resources Information Center

Presents a lesson plan for introducing students in grades four through six to Thomas Moran's painting, "The Grand Canyon." The goal of the lesson is to illustrate the importance of the American West as a subject for artists in the nineteenth century. (JDH)

Brubaker, Ann

1986-01-01

77

Duration and rates of discharge: Maja Valles, Mars  

NASA Technical Reports Server (NTRS)

The 1600 km-long Maja Valles outflow system of Mars consists of three major divisions including the upper valley on Lunae Planum, the canyon section across Xanthe Terra, and the lower valley across western Chryse Planitia. Although water released from the source in Juventae Chasma could reach the terminus of the present day valley system in central Chryse Planitia within 44 hours, the original outflow did not traverse the Martian surface in a direct path. It ponded along its course on northern Lunae Planum and near the western edge of Chryse Planitia significantly prolonging the lifetime of surface flow. Calculation of pond volumes and discharge rates through various parts of the channel system indicates that water flowed through this system for nearly a (terrestrial) year. Discharge rates from the various basins along the Maja channels and the maximum flow rates within the various channels are calculated. With this data, it is possible to place reasonable estimates of the minimum length of time required to drain the various impoundments and the duration of flow in various parts of the channel system. The results of these calculations are discussed.

Dehon, R. A.; Pani, E. A.

1992-01-01

78

Amplification of bedrock canyon incision by wind  

NASA Astrophysics Data System (ADS)

Bedrock canyons etch much of the surface of Earth and Mars, and commonly inform interpretations of long-term hydrologic or tectonic changes within these landscapes. However, many bedrock canyons (particularly on Mars) exist in arid environments where wind abrasion can dramatically alter surface morphology. Although it is hypothesized that wind carves or modifies bedrock canyons on Mars, the interplay of wind and fluvial processes in shaping canyon landscapes is, to our knowledge, unexplored. Consequently, here we exploit a natural experiment along the 4.09 Ma Puripicar ignimbrite, situated on the western slope of the Andes in the Atacama Desert and subject to significant erosion from both wind and rivers. The Puripicar exhibits a series of bedrock gorges nested behind a broad north-south escarpment whose southern half is protected from wind by a large topographic barrier. This shielding provides a natural control to examine the effects of wind abrasion on canyon morphology and in particular knickpoint retreat. Our results show that for a given drainage area, knickpoints in wind-affected canyons have incised an order of magnitude farther upstream than wind-protected canyons. In addition, wind-affected canyons are wider and have more streamlined aspect ratios for a given drainage area than wind-protected canyons. Aeolian abrasion appears to result in knickpoints with average slopes half those of shielded canyons (0.2 and 0.4, respectively). Lastly, although the magnitude of knickpoint retreat is larger in wind-affected canyons, the scaling exponent between knickpoint retreat and drainage area is virtually identical for wind-affected canyons (0.56, R = 0.71) and wind-protected canyons (0.60, R = 0.80). Taken together, our results suggest that fluvial incision and wind abrasion are coupled processes in this landscape: convergent canyons funnel wind towards knickpoints, thereby leading to enhanced aeolian abrasion rates at knickpoints. We speculate that the apparent drainage area dependence of knickpoint retreat in wind-affected canyons reflects the fact that larger rivers create wider canyon mouths. Larger canyons mouths, in turn, increase wind convergence and drive higher aeolian abrasion rates at the heads of larger canyons. This study is the first to demonstrate knickpoint retreat via wind abrasion, and highlights that even in landscapes where large river gorges are present, wind may still exert a dominant control on canyon morphology.

Perkins, J. P.; Finnegan, N. J.; de Silva, S. L.

2013-12-01

79

A morphologic analysis of Granicus Valles, Mars  

E-print Network

Valles is located near the base of the slope of the Elysium Mons volcano and adjacent to some lava or pyroclastic flows, therefore, one should consider the possibility of lava eroding these channels. Volcanism in this region has been studied... Valles is located near the base of the slope of the Elysium Mons volcano and adjacent to some lava or pyroclastic flows, therefore, one should consider the possibility of lava eroding these channels. Volcanism in this region has been studied...

Brandstrom, Gary Wayne

2012-06-07

80

The Danube submarine canyon (Black Sea): morphology and sedimentary processes  

Microsoft Academic Search

The Danube Canyon is a large shelf-indenting canyon that has developed seaward of the late Pleistocene paleo–Danube valley. Mechanisms of canyon evolution and factors that controlled it are revealed by analyzing the morphology and the sedimentary structure of the canyon, as well as the main features of the continental margin around the canyon. This is based on investigation by swath

Irina Popescu; Gilles Lericolais; Nicolae Panin; Alain Normand; Cornel Dinu; Eliane Le Drezen

2004-01-01

81

The Danube submarine canyon (Black Sea): morphology and sedimentary processes  

Microsoft Academic Search

The Danube Canyon is a large shelf-indenting canyon that has developed seaward of the late Pleistocene paleo-Danube valley. Mechanisms of canyon evolution and factors that controlled it are revealed by analyzing the morphology and the sedimentary structure of the canyon, as well as the main features of the continental margin around the canyon. This is based on investigation by swath

Irina Popescu; Gilles Lericolais; Nicolae Panin; Alain Normand

82

Geomorphic process fingerprints in submarine canyons  

USGS Publications Warehouse

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.

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

2013-01-01

83

Internal geology and evolution of the Redondo dome, Valles caldera, New Mexico  

NASA Astrophysics Data System (ADS)

A detailed inventory was made of subsurface samples taken from deep geothermal test wells drilled in the resurgent Redondo dome in the Valles caldera of New Mexico. Attention was focused on the relationships between the Bandelier Tuff and accompanying felsic tuffs and sediments. Welded and nonwelded ash flow tuff rocks deposited on the surface of the Pliocene Palizer Canyon Formation were taken as representing small erruptions correllated with the 3.1-3.6 Myr-old tuffs. Upper parts of the tuffs were eroded away and replaced by tuffaceous sandstone. The Tshirege portion of the Bandolier Tuff, containing a thick interior zone of granophyric crystallization, was deposited just before the beginning of the uplift of the Redondo dome. A comparison of the uplift with a model for formation of the laccoliths of the Henry Mountains indicated the magma was 4700 m thick, in line with the fact that the 3243 m bore hole did not reach the pluton responsible for the doming.

Nielson, D. L.; Hulen, J. B.

1984-09-01

84

ACCELERATED PILOT PROJECT FOR U CANYON DEMOLITION  

SciTech Connect

At the U.S. Department of Energy's Hanford Site in southeast Washington State, CH2M HILL Plateau Remediation Company (CH2M HILL) is underway on a first-of-a-kind project with the decommissioning and demolition of the U Canyon. Following the U.S. Environmental Protection Agency's Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) Record of Decision for the final remediation of the canyon, CH2M HILL is combining old and new technology and techniques to prepare U Canyon for demolition. The selected remedial action called first for consolidating and grouting equipment currently in the canyon into lower levels of the plant (openings called cells), after which the cell galleries, hot pipe trench, ventilation tunnel, drains and other voids below the operating deck and crane-way deck levels will be filled with approximately 20,000 cubic yards of grout and the canyon roof and walls demolished down to the approximate level of the canyon deck. The remaining canyon structure will then be buried beneath an engineered barrier designed to control potential contaminant migration for a 500-year life. Methods and lessons learned from this project will set the stage for the future demolition of Hanford's four other canyon-type processing facilities.

KEHLER KL

2011-01-13

85

DESCHUTES CANYON ROADLESS AREA, OREGON.  

USGS Publications Warehouse

An examination of the Deschutes Canyon Roadless Area, Oregon indicated that the area is devoid of mines and active mineral prospects or claims and that there is little likelihood for the occurrence of metallic or nonmetallic mineral resources. There is no evidence to indicate that mineral fuels are present in the roadless area. Nearby parts of central Jefferson County on the Warm Springs Indian Reservation are characterized by higher-than-normal heat flow and by numerous thermal springs, some of which have been partly developed. This may indicate that the region has some as yet undefined potential for the development of geothermal energy.

Walker, George, W.; Winters, Richard, A.

1984-01-01

86

Flow dynamics around downwelling submarine canyons  

NASA Astrophysics Data System (ADS)

Flow dynamics around a downwelling submarine canyon were analysed with the Massachusetts Institute of Technology general circulation model. Blanes Canyon (northwestern Mediterranean) was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby and Burger numbers were used to determine the significance of Coriolis acceleration and stratification (respectively) and their impacts on flow dynamics. A new non-dimensional parameter (?) was introduced to determine the significance of vertical variations in stratification. Some simulations do see brief periods of upwards displacement of water during the 10-day model period; however, the presence of the submarine canyon is found to enhance downwards advection of density in all model scenarios. High Burger numbers lead to negative vorticity and a trapped anticyclonic eddy within the canyon, as well as an increased density anomaly. Low Burger numbers lead to positive vorticity, cyclonic circulation, and weaker density anomalies. Vertical variations in stratification affect zonal jet placement. Under the same forcing conditions, the zonal jet is pushed offshore in more uniformly stratified domains. The offshore jet location generates upwards density advection away from the canyon, while onshore jets generate downwards density advection everywhere within the model domain. Increasing Rossby values across the canyon axis, as well as decreasing Burger values, increase negative vertical flux at shelf break depth (150 m). Increasing Rossby numbers lead to stronger downwards advection of a passive tracer (nitrate), as well as stronger vorticity within the canyon. Results from previous studies are explained within this new dynamic framework.

Spurgin, J. M.; Allen, S. E.

2014-10-01

87

Mars Science Laboratory at Canyon  

NASA Technical Reports Server (NTRS)

December 2, 2003

NASA's Mars Science Laboratory travels near a canyon on Mars in this artist's concept. The mission is under development for launch in 2009 and a precision landing on Mars in 2010.

Once on the ground, the Mars Science Laboratory would analyze dozens of samples scooped up from the soil and cored from rocks as it explores with greater range than any previous Mars rover. It would investigate the past or present ability of Mars to support life. NASA is considering nuclear energy for powering the rover to give it a long operating lifespan.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., is managing development of the Mars Smart Laboratory for the NASA Office of Space Science, Washington, D.C.

2003-01-01

88

Flow Structure in a Bedrock Canyon (Invited)  

NASA Astrophysics Data System (ADS)

Bedrock canyon incision is widely recognized as setting the pace of landscape evolution. A variety of models link flow and sediment transport processes to the bedrock canyon incision rate. The model components that represent sediment transport processes are quite well developed in some models. In contrast, the model components that represent fluid flow remain rudimentary. Part of the reason is that there have been relatively few observations of flow structure in a bedrock canyon. Here, we present observations of flow obtained using an array of three acoustic Doppler current profilers during a 524 km long continuous centerline traverse of the Fraser River, British Columbia, Canada as it passes through a series of bedrock canyons. Through this portion of the river, the channel alternates between gravel-bedded reaches that are deeply incised into semi-consolidated glacial deposits and solid bedrock-bound reaches. We present observations of flow through 41 bedrock bound reaches of the river, derived from our centerline traverses and more detailed three-dimensional mapping of the flow structure in 2 canyons. Our observations suggest that flow in the most well-defined canyons (deep, laterally constrained, completely bedrock bound) is far more complex than that in a simple prismatic channel. As flow enters the canyon, a high velocity core plunges from the surface to the bed, causing a velocity inversion (high velocities at the bed and low velocities at the surface). This plunging flow then upwells along the canyon wall, resulting in a three-dimensional flow with counter-rotating, along-stream eddies that diverge near the bed. We observe centerline ridges along the canyon floors that result from the divergence and large-scale surface boils caused by the upwelling. This flow structure causes deep scour in the bedrock channel floor, and ensures the base of the canyon walls are swept of debris that otherwise may be deposited due to lower shear stresses abutting the walls. The observations suggest that the modeling approaches currently included in landscape evolution theories may be inadequate to capture the morphodynamics of bedrock canyons.

Venditti, J. G.; Rennie, C. D.; Church, M. A.; Bomhof, J.; Lin, M.

2013-12-01

89

Structure of Flow in a Bedrock Canyon  

NASA Astrophysics Data System (ADS)

Bedrock canyon incision is widely recognized as setting the pace of landscape evolution. A variety of models link flow and sediment transport processes to the bedrock canyon incision rate. The model components that represent sediment transport processes are quite well developed in some models. In contrast, the model components that represent fluid flow remain rudimentary. Part of the reason is that there have been relatively few observations of flow structure in a bedrock canyon. Here, we present observations of flow obtained using an array of three acoustic Doppler current profilers during a 524 km long continuous centerline traverse of the Fraser River, British Columbia, Canada as it passes through a series of bedrock canyons. Through this portion of the river, the channel alternates between gravel-bedded reaches that are deeply incised into semi-consolidated glacial deposits and solid bedrock-bound reaches. We present observations of flow through 41 bedrock bound reaches of the river, derived from our centerline traverses and more detailed three-dimensional mapping of the flow structure in 2 canyons. Our observations suggest that flow in the most well-defined canyons (deep, laterally constrained, completely bedrock bound) is far more complex than that in a simple prismatic channel. As flow enters the canyon, a high velocity core plunges from the surface to the bed, causing a velocity inversion (high velocities at the bed and low velocities at the surface). This plunging flow then upwells along the canyon wall, resulting in a three-dimensional flow with counter-rotating, along-stream eddies that diverge near the bed. We observe centerline ridges along the canyon floors that result from the divergence and large-scale surface boils caused by the upwelling. This flow structure causes deep scour in the bedrock channel floor, and ensures the base of the canyon walls are swept of debris that otherwise may be deposited due to lower shear stresses abutting the walls. The observations suggest that the rudimentary modeling approaches currently included in landscape evolution theories are inadequate to capture the morphodynamics of bedrock canyons.

Venditti, J. G.; Rennie, C. D.; Church, M. A.; Bomhof, J.; Lin, M.

2012-12-01

90

75 FR 26098 - Safety Zone; Under Water Clean Up of Copper Canyon, Lake Havasu, AZ  

Federal Register 2010, 2011, 2012, 2013

...Safety Zone; Under Water Clean Up of Copper Canyon...sponsoring the Under Water Copper Canyon Clean up, which will involve...zone; Copper Canyon Clean Up, Lake Havasu, AZ...zone will include all waters of Copper Canyon...

2010-05-11

91

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

Federal Register 2010, 2011, 2012, 2013

...consultation requirements of the Grand Canyon Protection Act (Pub. L. 102-575...Technical Work Group (TWG), a Grand Canyon Monitoring and Research Center...Canyon Dam consistent with the Grand Canyon Protection Act. The TWG is a...

2010-01-05

92

Mission Canyon (Mississippian) reservoir study, Whitney Canyon-Carter Creek Field, southwestern Wyoming thrust belt  

Microsoft Academic Search

Whitney Canyon-Carter Creek field is a giant sour gas and condensate reservoir located in extreme southwestern Wyoming in the Fossil basin area of the Wyoming thrust belt. Discovered in 1977, the field contains 36 wells within an area 13 mi long and 2 mi wide. Porous dolomites of the Mississippian Mission Canyon formation contain over 70% of total proven reserves.

J. L. Sieverding; P. E. Flynn; P. M. Harris

1987-01-01

93

Karst hydrology of Grand Canyon, Arizona, USA  

NASA Astrophysics Data System (ADS)

SummaryCaves in Grand Canyon, Arizona, USA fall into two main categories: those formed under unconfined conditions and those formed under confined conditions. This study focuses on the hydrology and paleohydrology of the confined caves in the Redwall-Muav aquifer, where the aquifer is overlain by rocks of the Supai Group and underlain by the Bright Angel Shale. Unconfined caves are discussed only in their relation to confined caves. Discharge for confined groundwater was, as it is today, primarily from the Redwall Limestone where it has been incised by the main canyon or its tributaries and where it has converged along a structural low or fault. Descent of the potentiometric surface (or water table) over time is recorded by one ore episode and six cave episodes: (1) emplacement of Cu-U ore, (2) precipitation of iron oxide in cavities, (3) dissolution of cave passages, (4) precipitation of calcite-spar linings over cave passage walls, (5) precipitation of cave mammillary coatings, (6) minor replacement of cave wall and ceiling limestone by gypsum, and (7) deposition of subaerial speleothems. The mammillary episode records the approximate position of the water table when the incision of the canyon was at that level. Discharge toward spring points has reorganized and adjusted with respect to ongoing canyon and side-canyon incision. The dissolution of Grand Canyon confined caves was the result of the mixing of epigene waters with hypogene waters so that undersaturation with respect to calcite was achieved. The karst hydrology of Grand Canyon may be unique compared to other hypogene cave areas of the world.

Hill, C. A.; Polyak, V. J.

2010-09-01

94

MC-18 Coprates Region  

NASA Technical Reports Server (NTRS)

Mars digital-image mosaic merged with color of the MC-18 quadrangle, Coprates region of Mars. Moderately cratered and faulted highland ridged plains in the northern and southern parts are cut by the prominent Valles Marineris chasma system, which reaches depths of 10 km and extends in an east-southeast direction for about 2,500 km across the quadrangle. The long, central canyons appear to be large, fault-bounded rifts, whereas some of the isolated, northern canyons are the sources of large outflow channels. Latitude range -30 to 0 degrees, longitude range 45 to 90 degrees.

1994-01-01

95

Mineral resources of the Fish Creek Canyon, Road Canyon, and Mule Canyon Wilderness Study Areas, San Juan County, Utah  

SciTech Connect

This book reports the Fish Creek Canyon (UT-060-204), Road Canyon(UT-060-201), and Mule Canyon (UT-060-205B) Wilderness Study Areas, which comprise 40,160 acres, 52,420 acres, and 5,990 acres, respectively, studied for their mineral endowment. A search of federal, state, and county records showed no current or previous mining-claim activity. No mineral resources were identified during field examination of the study areas. Sandstone and sand and gravel have no unique qualities but could have limited local use for road metal or other construction purposes. However, similar materials are abundant outside the study areas. The three study areas have moderate resource potential for undiscovered oil and gas and low resource potential for undiscovered metals, including uranium and thorium, coal, and geothermal energy.

Bove, D.J.; Shawe, D.R.; Lee, G.K.; Hanna, W.F. (Geological Survey, Reston, VA (USA)); Jeske, R.E. (US Bureau of Mines (US))

1989-01-01

96

Contemporary sediment-transport processes in submarine canyons.  

PubMed

Submarine canyons are morphological incisions into continental margins that act as major conduits of sediment from shallow- to deep-sea regions. However, the exact mechanisms involved in sediment transfer within submarine canyons are still a subject of investigation. Several studies have provided direct information about contemporary sedimentary processes in submarine canyons that suggests different modes of transport and various triggering mechanisms. Storm-induced turbidity currents and enhanced off-shelf advection, hyperpycnal flows and failures of recently deposited fluvial sediments, dense shelf-water cascading, canyon-flank failures, and trawling-induced resuspension largely dominate present-day sediment transfer through canyons. Additionally, internal waves periodically resuspend ephemeral deposits within canyons and contribute to dispersing particles or retaining and accumulating them in specific regions. These transport processes commonly deposit sediments in the upper- and middle-canyon reaches for decades or centuries before being completely or partially flushed farther down-canyon by large sediment failures. PMID:23937169

Puig, Pere; Palanques, Albert; Martín, Jacobo

2014-01-01

97

Flow and mixing in Juan de Fuca Canyon, Washington  

NASA Astrophysics Data System (ADS)

We report breaking internal lee waves, strong mixing, and hydraulic control associated with wind-driven up-canyon flow in Juan de Fuca Canyon, Washington. Unlike the flow above the canyon rim, which shows a tidal modulation typical on continental shelves, the flow within the canyon is persistently up-canyon during our observations, with isopycnals tilted consistent with a geostrophic cross-canyon momentum balance. As the flow encounters a sill near the canyon entrance at the shelf break, it accelerates significantly and undergoes elevated mixing on the upstream and downstream sides of the sill. On the downstream side, a strong lee wave response is seen, with displacements of O(100 m) and overturns tens of meters high. The resulting diffusivity is O(10-2 m2 s-1), sufficient to substantially modify coastal water masses as they transit the canyon and enter the Salish Sea estuarine system.

Alford, Matthew H.; MacCready, Parker

2014-03-01

98

Submarine origin for the Neoproterozoic Wonoka canyons, South Australia  

NASA Astrophysics Data System (ADS)

An examination of the deeply incised Ediacaran Wonoka canyons in the Adelaide Geosyncline (most recently interpreted as subaerial valleys) demonstrates their submarine origin, and confirms them as some of the best examples of ancient outcropping submarine canyons in the world. The entire canyon-fill succession is interpreted to be of deep-water (below wave base) origin, consisting of calcareous shale and siltstone together with a variety of mass-flow deposits including turbidites, grain flows and debris flows. The canyon fill lacks definitive shallow-water structures (e.g. mud cracks, fenestral fabrics or wave ripples) at all stratigraphic levels. Canyon-lining carbonate crusts that have previously been interpreted as non-marine calcretes or tufas (and used to suggest a non-marine origin for the canyons) are argued to be of deep-water, marine, microbial origin. Extremely negative carbon isotope values from the canyon-fill and canyon-lining crusts have a primary marine origin. Previously interpreted deepening upward trends in the canyon fill (used as evidence of a subaerial erosion episode followed by drowning) are suggested to be fining upward trends, caused by the transition from canyon cutting to canyon filling, with the majority of the fill being of deep-water slope origin. The basal conglomeratic canyon-fill sediments represent the last vestiges of the high-energy, deep-water, canyon-erosion environment in which the incisions formed. A deep-water origin for the canyons is consistent with all previous stratigraphic observations of the Wonoka canyons, including the conspicuous lack of regional unconformities in the lower Wonoka Formation, and their emanation from the deep-water facies of the Wonoka Formation. A submarine canyon origin also removes the need for extreme (~ 1 km) relative sea level fluctuation and associated problems (i.e. an enclosed basin with Messinian-style evaporative drawdown or thermal uplift above a migrating mantle plume) required by the subaerial valley hypotheses.

Giddings, J. A.; Wallace, M. W.; Haines, P. W.; Mornane, K.

2010-01-01

99

THE SIGNIFICANCE OF ODOR FOR BEES ORIENTING ACROSS A CANYON  

E-print Network

THE SIGNIFICANCE OF ODOR FOR BEES ORIENTING ACROSS A CANYON Franz Josef BOGDANY* Stephen TABER, III* SUMMARY Honey bees (Apis mellifera L.) were step-guided across a 1,200 m wide and 200 m deep canyon. When the food source on the opposite rim of the canyon as opposed to when no scent was presented. No bees were

Boyer, Edmond

100

75 FR 34476 - Glen Canyon Dam Adaptive Management Work Group  

Federal Register 2010, 2011, 2012, 2013

...INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY...renewing the charter for the Glen Canyon Dam Adaptive Management Work Group. The purpose...respect to the operation of Glen Canyon Dam and the exercise of other authorities...

2010-06-17

101

27 CFR 9.217 - Happy Canyon of Santa Barbara.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Happy Canyon of Santa Barbara. 9.217 Section 9.217...Viticultural Areas § 9.217 Happy Canyon of Santa Barbara. (a) Name. The name of...described in this section is “Happy Canyon of Santa Barbara”. For purposes of part 4 of...

2012-04-01

102

27 CFR 9.217 - Happy Canyon of Santa Barbara.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Happy Canyon of Santa Barbara. 9.217 Section 9.217...Viticultural Areas § 9.217 Happy Canyon of Santa Barbara. (a) Name. The name of...described in this section is “Happy Canyon of Santa Barbara”. For purposes of part 4 of...

2010-04-01

103

27 CFR 9.217 - Happy Canyon of Santa Barbara.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Happy Canyon of Santa Barbara. 9.217 Section 9.217...Viticultural Areas § 9.217 Happy Canyon of Santa Barbara. (a) Name. The name of...described in this section is “Happy Canyon of Santa Barbara”. For purposes of part 4 of...

2013-04-01

104

27 CFR 9.217 - Happy Canyon of Santa Barbara.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Happy Canyon of Santa Barbara. 9.217 Section 9.217...Viticultural Areas § 9.217 Happy Canyon of Santa Barbara. (a) Name. The name of...described in this section is “Happy Canyon of Santa Barbara”. For purposes of part 4 of...

2011-04-01

105

27 CFR 9.217 - Happy Canyon of Santa Barbara.  

...2014-04-01 false Happy Canyon of Santa Barbara. 9.217 Section 9.217...Viticultural Areas § 9.217 Happy Canyon of Santa Barbara. (a) Name. The name of...described in this section is “Happy Canyon of Santa Barbara”. For purposes of part 4 of...

2014-04-01

106

Study of Pollutant Dispersion in an Urban Street Canyon.  

National Technical Information Service (NTIS)

Pollutant dispersion from an urban street canyon was studied to determine the process by which pollutants emitted at street level are transported from the canyon and to quantify the net rate of pollutant exchange between the canyon and the upper air. The ...

F. T. DePaul, C. M. Sheih

1984-01-01

107

Cascading-driven upwelling in submarine canyons at high latitudes  

Microsoft Academic Search

Numerical simulations and laboratory experiments confirm my initial research hypothesis stating that dense-water cascading down a submarine canyon induces localized upwelling of deeper water onto the shelf. This process, not described before, is associated with internal deformation radii inherent in the cascading process being less the canyon width and geostrophic adjustment of a density front that establishes along the canyon

Jochen Kämpf

2005-01-01

108

27 CFR 9.152 - Malibu-Newton Canyon.  

...2014-04-01 2014-04-01 false Malibu-Newton Canyon. 9.152 Section 9.152...Viticultural Areas § 9.152 Malibu-Newton Canyon. (a) Name. The name of...described in this petition is “Malibu-Newton Canyon.” (b) Approved maps....

2014-04-01

109

27 CFR 9.152 - Malibu-Newton Canyon.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Malibu-Newton Canyon. 9.152 Section 9.152...Viticultural Areas § 9.152 Malibu-Newton Canyon. (a) Name. The name of...described in this petition is “Malibu-Newton Canyon.” (b) Approved maps....

2011-04-01

110

27 CFR 9.152 - Malibu-Newton Canyon.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Malibu-Newton Canyon. 9.152 Section 9.152...Viticultural Areas § 9.152 Malibu-Newton Canyon. (a) Name. The name of...described in this petition is “Malibu-Newton Canyon.” (b) Approved maps....

2010-04-01

111

27 CFR 9.152 - Malibu-Newton Canyon.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Malibu-Newton Canyon. 9.152 Section 9.152...Viticultural Areas § 9.152 Malibu-Newton Canyon. (a) Name. The name of...described in this petition is “Malibu-Newton Canyon.” (b) Approved maps....

2013-04-01

112

27 CFR 9.152 - Malibu-Newton Canyon.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Malibu-Newton Canyon. 9.152 Section 9.152...Viticultural Areas § 9.152 Malibu-Newton Canyon. (a) Name. The name of...described in this petition is “Malibu-Newton Canyon.” (b) Approved maps....

2012-04-01

113

The Grand Canyon: Its Youngest Rocks  

NSDL National Science Digital Library

This video segment adapted from NOVA shows a dramatic landscape created by relatively recent rock-forming activity in the Grand Canyon. Volcanic eruptions only a million years ago created the canyon's youngest rocks. In contrast with the much older Vishnu Schist formation, this younger rock has been much more susceptible to physical change. When three-hundred-meter (thousand-foot) lava dams periodically blocked the river, they were quickly eroded away and river flow restored. A background essay and list of discussion questions are included.

2011-03-14

114

The Colorado River in the Grand Canyon.  

ERIC Educational Resources Information Center

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 aquatic…

Speece, Susan

1991-01-01

115

Vision-Based Navigation through Urban Canyons  

E-print Network

27 December 2008 We address the problem of navigating unmanned vehicles safely through urban canyons to the front while remaining centered between obstacles to the side. Through experiments on an unmanned ground, including T-junctions and 90-deg bends. Experiments on a rotorcraft unmanned aerial vehicle, which

Sukhatme, Gaurav S.

116

Geology of the Nine Canyon Map Area.  

National Technical Information Service (NTIS)

The basalt stratigraphy and structure of a 175-square kilometer area (the Nine Canyon Map Area) along the southern margin of the Pasco Basin have been studied to help assess the feasibility of a nuclear waste terminal storage facility. Detailed mapping sh...

M. G. Jones, R. D. Landon

1978-01-01

117

Creationism in the Grand Canyon, Texas Textbooks  

NASA Astrophysics Data System (ADS)

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.

Folger, Peter

2004-01-01

118

Grassland in the Valle Grande, Valles Caldera National Preserve, New Mexico, near sunrise.  

NSDL National Science Digital Library

The Valle Grande in the Valles Caldera National Preserve, New Mexico is one of the National Science FoundationÃÂs Ecology of Infectious Disease study sites. A recent study examined the role that local environmental changes play in deer mouse (Peromyscus maniculatus) and Sin Nombre virus distributions. Hantavirus Pulmonary Syndrome (HPS) is a human disease caused by infection with hantaviruses, which are maintained in rodent populations. HPS was recognized following an outbreak of pulmonary disease among humans in the U.S. Southwest in 1993, and infection with Sin Nombre virus (SNV) was traced to its reservoir, the deer mouse. The number of HPS cases varies both geographically and among years, and it has been hypothesized that the variation reflects environmental changes that affect rodent populations. This photograph originally appeared on the cover of Ecological Applications (17:1) in February of 2007.

Norris, Douglas E.

2010-02-15

119

Living Legacy: A Conversation with Carolina Gomez del Valle.  

ERIC Educational Resources Information Center

Carolina Gomez del Valle has been involved in training other Montessorians in Mexico, Chile, Nicaragua, Peru, and Taiwan. This interview explores her experiences with Montessori education and describes how she has woven her religious training and Montessori philosophy together. (PAM)

Montessori Life, 1993

1993-01-01

120

Sedimentary processes in the middle Nazaré Canyon  

NASA Astrophysics Data System (ADS)

Nazaré Canyon extends from a water depth of 50 m near the Portuguese coast to 5000 m at the edge of the Iberian Abyssal Plain. The system is not connected to a modern river and instead obtains its present day sediment input by capture of along-shelf sediment transport. Much of this sediment is deposited in the middle canyon between about 2700 and 3800 m. However, the middle canyon is a highly heterogeneous environment, with areas of both high and low sedimentation rates, exposed rock outcrop, erosion and stable and unstable slopes in close juxtaposition. This paper explores how the various sedimentary processes interact to create the observed heterogeneous canyon environment, which will influence benthic biodiversity in the canyon. Seafloor heterogeneity is investigated using a nested approach to data interpretation, using local high-resolution data to calibrate regional lower resolution data. Six different data types, ship and ROV-mounted swath bathymetry, 30 kHz sidescan sonar images, sediment cores, seafloor video/photographs and current metre/acoustic backscatter data, were incorporated into the analysis. The main morphological characteristic of the middle canyon is a narrow, steep-sided, axial channel flanked by gently sloping terraces. Small-scale landsliding, active at the present day, is the main process that exposes a variety of substrates, ranging from semi-consolidated Holocene sediments to rock of probable Mesozoic age, on the steep axial channel walls. The axial channel floor is characterised in part by large-scale sediment bedforms and in part by landslide debris, suggesting some reworking of landslide debris by currents within the channel. The terraces are interpreted as inner levees with high sedimentation rates. Cores show a dominantly muddy sequence interrupted by thin turbidite sands emplaced on decadal to centennial timescales. The fine-grained sedimentation is the product of continuous settling from fine-grained flows that range from gravity currents to lateral advection of nepheloid layers. The close proximity of areas of high sedimentation and erosion creates a highly heterogeneous seafloor, with the highest heterogeneity on the steepest slopes.

Masson, D. G.; Huvenne, V. A. I.; de Stigter, H. C.; Arzola, R. G.; LeBas, T. P.

2011-12-01

121

Canyon conditions impact carbon flows in food webs of three sections of the Nazaré canyon  

NASA Astrophysics Data System (ADS)

Submarine canyons transport large amounts of sediment and organic matter (OM) from the continental shelf to the abyssal plain. Three carbon-based food web models were constructed for the upper (300-750 m water depth), middle (2700-3500 m) and lower section (4000-5000 m) of the Nazaré canyon (eastern Atlantic Ocean) using linear inverse modeling to examine how the food web is influenced by the characteristics of the respective canyon section. The models were based on an empirical dataset consisting of biomass and carbon processing data, and general physiological data constraints from the literature. Environmental conditions, most notably organic matter (OM) input and hydrodynamic activity, differed between the canyon sections and strongly affected the benthic food web structure. Despite the large difference in depth, the OM inputs into the food webs of the upper and middle sections were of similar magnitude (7.98±0.84 and 9.30±0.71 mmol C m -2 d -1, respectively). OM input to the lower section was however almost 6-7 times lower (1.26±0.03 mmol C m -2 d -1). Carbon processing in the upper section was dominated by prokaryotes (70% of total respiration), though there was a significant meiofaunal (21%) and smaller macrofaunal (9%) contribution. The high total faunal contribution to carbon processing resembles that found in shallower continental shelves and upper slopes, although the meiofaunal contribution is surprisingly high and suggest that high current speeds and sediment resuspension in the upper canyon favor the role of the meiofauna. The high OM input and conditions in the accreting sediments of the middle canyon section were more beneficial for megafauna (holothurians), than for the other food web compartments. The high megafaunal biomass (516 mmol C m -2), their large contribution to respiration (56% of total respiration) and secondary production (0.08 mmol C m -2 d -1) shows that these accreting sediments in canyons are megafaunal hotspots in the deep-sea. Conversely, carbon cycling in the lower canyon section was strongly dominated by prokaryotes (86% of respiration) and the food web structure therefore resembled that of lower slope and abyssal plain sediments. This study shows that elevated OM input in canyons may favor the faunal contribution to carbon processing and create hotspots of faunal biomass and carbon processing along the continental shelf.

van Oevelen, Dick; Soetaert, Karline; Garcia, R.; de Stigter, Henko C.; Cunha, Marina R.; Pusceddu, Antonio; Danovaro, Roberto

2011-12-01

122

Flood Geology and the Grand Canyon: A Critique  

Microsoft Academic Search

Four claims of Flood Geology—as they are related to the Grand Canyon and specifically to the book Grand Canyon: A Different View—are evaluated by directly addressing Young Earth Creationist arguments, by showing rock features that belie these claims, and by presenting the most up-to-date scientific theories on the origin of the Grand Canyon. We conclude that Young Earth Creationism promotes

Carol A. Hill; Stephen O. Moshier

2009-01-01

123

Numerical estimation of the effective albedo of an urban canyon  

Microsoft Academic Search

Summary  The paper focuses on the absorption of shortwave radiation in an urban street canyon. To test the effective albedo of the\\u000a canyon an analytic solution of the multiple reflection problem is applied. The infinitesimally long canyon is divided into\\u000a slices and a matrix of view factors for the slices is defined. Incoming shortwave radiation includes direct and diffuse parts\\u000a and

K. Fortuniak

2008-01-01

124

Lake Powell, Colorado River, Utah and Grand Canyon, Arizona  

NASA Technical Reports Server (NTRS)

In this stark desert scene, Lake Powell, the Colorado River and the Grand Canyon (36.5N, 111.5W) provide the only relief and source of water. The creation of Lake Powell by the building of the Glen Canyon High Dam led directly to the establishment of a National Recreation Area surrounding the lakes. To the south, following the course of the Colorado River, the NE corner of Grand Canyon can be seen.

1973-01-01

125

Holocene sedimentary activity in a non-terrestrially coupled submarine canyon: Cook Strait Canyon system, New Zealand  

NASA Astrophysics Data System (ADS)

The Cook Strait Canyon system, located between the North and South islands of New Zealand, is a large (1800 km2), multi-branching, shelf-indenting canyon on an active subduction margin. The canyon comes within 1 km of the coast, but does not intercept fluvial or littoral sediment systems and is therefore defined as a non-terrestrially coupled system. Sediment transport associated with a strong tidal stream, and seafloor disturbance related to numerous high-activity faults, is known from previous studies. Little is known, however, about the rates of sedimentary activity in the canyon and the processes driving it. A substantial dataset of EM300 multibeam bathymetry, gravity cores, 3.5 kHz seismic reflection profiles, camera and video transects and current meter data have been collected across the region between 2002 and 2011. The canyon system therefore provides an excellent study area for understanding sediment transport in a non-coupled submarine canyon system. Analysis of the data reveals a two-staged sediment transport system where: (1) oceanographic (tidal) processes mobilise sediment from the continental shelf and transport it to depocentres in the upper-central canyons, and (2) tectonic (earthquake) processes remobilise sediment that is transported through the lower canyon to the deep ocean. Tidal boundary-layer currents within the canyon reach velocities up to 0.53 m/s and are capable of mobilising fine sand in the central reach of the upper canyons. The velocity is higher at the canyon rim and capable of mobilising coarse sand. Sediment depocentres resulting from this tidally forced sediment transport have a well formed geomorphology within the mid-upper canyon arms of Cook Strait and Nicholson Canyons. Pseudo-static stability modelling, supported by sediment core analysis, indicates that sediment accumulated in the upper canyons fails during seismic events approximately every 100 years. The 100 year return period ground shaking-level (peak ground acceleration, ignoring the effect of the water column above the seabed) at this site is estimated to be 0.23g. Fresh rock outcrops and bed-scour in the lower canyon floor indicate that remobilised material is transported to the deep ocean. The processes identified here are likely to be analogous to those occurring in many non-coupled shelf-indenting canyons on active margins globally, and provide a framework within which the biological response to geomorphic processes in submarine canyons can be assessed.

Mountjoy, J. J.; Micallef, A.; Stevens, C. L.; Stirling, M. W.

2014-06-01

126

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

Code of Federal Regulations, 2011 CFR

... Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California... Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California...000 yard radius of Diablo Canyon Nuclear Power Plant centered at position...

2011-07-01

127

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

Code of Federal Regulations, 2012 CFR

... Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California... Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California...000 yard radius of Diablo Canyon Nuclear Power Plant centered at position...

2012-07-01

128

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

Code of Federal Regulations, 2010 CFR

... Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California... Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California...000 yard radius of Diablo Canyon Nuclear Power Plant centered at position...

2010-07-01

129

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

Code of Federal Regulations, 2013 CFR

... Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California... Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California...000 yard radius of Diablo Canyon Nuclear Power Plant centered at position...

2013-07-01

130

78 FR 54482 - Charter Renewal, Glen Canyon Dam Adaptive Management Work Group  

Federal Register 2010, 2011, 2012, 2013

...4073000] Charter Renewal, Glen Canyon Dam Adaptive Management Work Group AGENCY...renewing the charter for the Glen Canyon Dam Adaptive Management Work Group. The purpose...concerning the operation of Glen Canyon Dam and the exercise of other authorities...

2013-09-04

131

DOI Strategic Sciences Working Group Mississippi Canyon 252/Deepwater Horizon Oil Spill  

E-print Network

DOI Strategic Sciences Working Group Mississippi Canyon 252/Deepwater Horizon Oil Spill Strategic Sciences Working Group Mississippi Canyon 252/Deepwater Horizon Oil Spill Progress Report Executive Summary Introduction and Objectives The Mississippi Canyon 252/Deepwater Horizon (MS252) oil spill

Torgersen, Christian

132

77 FR 5790 - Mississippi Canyon Gas Pipeline, LLC; Notice of Request Under Blanket Authorization  

Federal Register 2010, 2011, 2012, 2013

...CP12-49-000] Mississippi Canyon Gas Pipeline, LLC; Notice of Request Under...17, 2012, Mississippi Canyon Gas Pipeline, LLC (MCGP), 1100 Louisiana...Compliance, Mississippi Canyon Gas Pipeline, LLC, 1100 Louisiana Suite...

2012-02-06

133

78 FR 3879 - Ochoco National Forest, Paulina Ranger District; Oregon; Fox Canyon Cluster Allotment Management...  

Federal Register 2010, 2011, 2012, 2013

...Forest, Paulina Ranger District; Oregon; Fox Canyon Cluster Allotment Management Plan...allotments on the Paulina Ranger District. The Fox Canyon Cluster project area is located approximately...four allotments are Antler, Brush Creek, Fox Canyon, and Gray Prairie. The...

2013-01-17

134

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

...2014-07-01 false Copper Canyon, Lake Havasu, Colorado River-Regulated Navigation...District § 165.1171 Copper Canyon, Lake Havasu, Colorado River—Regulated Navigation...1) In the water area of Copper Canyon, Lake Havasu, Colorado River,...

2014-07-01

135

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

... Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California... Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California...000 yard radius of Diablo Canyon Nuclear Power Plant centered at position...

2014-07-01

136

78 FR 25404 - Proposed Establishment of Class E Airspace; Grand Canyon, AZ  

Federal Register 2010, 2011, 2012, 2013

...Establishment of Class E Airspace; Grand Canyon, AZ AGENCY: Federal Aviation...establish Class E airspace at the Grand Canyon VHF Omni-Directional Radio Range...VOR/DME) navigation aid, Grand Canyon, AZ, to facilitate...

2013-05-01

137

78 FR 40381 - Establishment of Class E Airspace; Grand Canyon, AZ  

Federal Register 2010, 2011, 2012, 2013

...Establishment of Class E Airspace; Grand Canyon, AZ AGENCY: Federal Aviation...establishes Class E airspace at the Grand Canyon VHF Omni-Directional Radio Range...VOR/DME) navigation aid, Grand Canyon, AZ, to facilitate...

2013-07-05

138

78 FR 35640 - Establishment of the Valle de Oro National Wildlife Refuge, Bernalillo County, New Mexico  

Federal Register 2010, 2011, 2012, 2013

...FF02R06000-FXRS1265022LPP-134] Establishment of the Valle de Oro National Wildlife Refuge, Bernalillo County...Service) has established the Valle de Oro National Wildlife Refuge as a unit of the...System. The Service established the Valle de Oro National Wildlife Refuge on September...

2013-06-13

139

The 322 ka Tiribí Tuff: stratigraphy, geochronology and mechanisms of deposition of the largest and most recent ignimbrite in the Valle Central, Costa Rica  

NASA Astrophysics Data System (ADS)

The Tiribí Tuff covered much of the Valle Central of Costa Rica, currently the most densely populated area in the country (˜2.4 million inhabitants). Underlying the tuff, there is a related well-sorted pumice deposit, the Tibás Pumice Layer. Based on macroscopic characteristics of the rocks, we distinguish two main facies in the Tiribí Tuff in correlation to the differences in welding, devitrification, grain size, and abundance of pumice and lithic fragments. The Valle Central facies consists of an ignimbritic plateau of non-welded to welded deposits within the Valle Central basin and the Orotina facies is a gray to light-bluish gray, densely to partially welded rock, with yellowish and black pumice fragments cropping out mainly at the Grande de Tárcoles River Gorge and Orotina plain. This high-aspect ratio ignimbrite (1:920 or 1.1×10-3) covered an area of at least 820 km2 with a long runout of 80 km and a minimum volume outflow of 25 km3 (15 km3 DRE). Geochemically, the tuff shows a wide range of compositions from basaltic-andesites to rhyolites, but trachyandesites are predominant. Replicate new 40Ar/39Ar age determinations indicate that widespread exposures of this tuff represent a single ignimbrite that was erupted 322±2 ka. The inferred source is the Barva Caldera, as interpreted from isopach and isopleth maps, contours of the ignimbrite top and geochemical correlation (˜10 km in diameter). The Tiribí Tuff caldera-forming eruption is interpreted as having evolved from a plinian eruption, during which the widespread basal pumice fall was deposited, followed by fountaining pyroclastic flows. In the SW part of the Valle Central, the ignimbrite flowed into a narrow canyon, which might have acted as a pseudo-barrier, reflecting the flow back towards the source and thus thickening the deposits that were filling the Valle Central depression. The variable welding patterns are interpreted to be a result of the lithostatic load and the influence of the content and size of lithic fragments.

Pérez, Wendy; Alvarado, Guillermo E.; Gans, Phillip B.

2006-07-01

140

A review of proposed Glen Canyon Dam interim operating criteria  

Microsoft Academic Search

Three sets of interim operating criteria for Glen Canyon Dam on the Colorado River have been proposed for the period of November 1991, to the completion of the record of decision for the Glen Canyon Dam environmental impact statement (about 1993). These criteria set specific limits on dam releases, including maximum and minimum flows, up-ramp and down-ramp rates, and maximum

K. LaGory; I. Hlohowskyj; D. Tomasko; J. Hayse; L. Durham

1992-01-01

141

The Grand Canyon of the Yellowstone Online Tour  

NSDL National Science Digital Library

This Yellowstone National Park website offers an online tour of the Grand Canyon of the Yellowstone. Prominent viewpoints of the canyon are highlighted with photos and information concerning their history. Other stops include information on giant glacial boulders and waterfalls. Similar tours of the Old Faithful area, the Norris Geyser Basin, the Fountain Paint Pots, and the Mammoth Hot Springs are also available online.

Park, Yellowstone N.

142

The Grand Canyon: The Top Two Rock Layers  

NSDL National Science Digital Library

Watch this short video clip to learn more about the rock layers of the Grand Canyon. This video discusses the two sandstone formations that comprise the uppermost part of the canyon. The video also discusses how the two sandstone layers were formed.

2006-01-01

143

Supplement to The Snake Hells Canyon Subbasin Plan Introduction  

E-print Network

1 Supplement to The Snake Hells Canyon Subbasin Plan Introduction This document was written.nwppc.org). Information in this supplement was reviewed and edited by the Hells Canyon Planning Team during the fall of 2004. This supplement is presented in four sections that correspond to information requested

144

Geologic controls on the morphology of La Aguja submarine canyon  

Microsoft Academic Search

The seascape of the continental shelf and slope offshore Santa Marta is sculpted by the submarine Aguja Canyon, a deep seafloor incision that extends from the inner shelf to the continental rise along some 115km. No major modern rivers flow into this canyon, thus ruling out principal fluvial control on the present geometry of this feature. Recently acquired multibeam sonar

Isabel C. Restrepo-Correa; Germán Y. Ojeda

2010-01-01

145

20140430_Green Machine Florida Canyon Hourly Data  

DOE Data Explorer

Employing innovative product developments to demonstrate financial and technical viability of producing electricity from low temperature geothermal fluids, coproduced in a mining operation, by employing ElectraTherm's modular and mobile heat-to-power "micro geothermal" power plant with output capacity expected in the 30-70kWe range. The Green Machine is an Organic Rankine Cycle power plant. The Florida Canyon machine is powered by geothermal brine with air cooled condensing. The data provided is an hourly summary from 01 April to 30 April 2014.

Joe Thibedeau

146

Topography within the axial channels of Monterey and Soquel Canyons  

NASA Astrophysics Data System (ADS)

Ultrahigh resolution surveys have been conducted that outline the topography and near seafloor structure within the axial channels of Monterey and Soquel Canyons. Multibeam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m at 50 m survey altitude) were collected using an autonomous underwater vehicle (AUV). An inertial navigation system combined with a doppler velocity sonar allows the AUV to fly through the sinuous canyons at 3 knots on a pre-programmed route while maintaining an altitude of 50 m above the bottom. The AUV has flown down through the sinuous canyons, passed where they join, to 1,900 m water depths, and obtained three or more overlapping swaths covering the axial channel floor and some of its adjacent flanks. One feature revealed in the multibeam bathymetry data are wave-like bedforms with wavelengths of 20 to 100 m and amplitudes up to 2.5 m oriented roughly perpendicular to the channel axis. These bedforms occur throughout the channel of Monterey Canyon. They are asymmetric with a steep face on the down-canyon side while the other face is nearly horizontal or dips up-canyon, and form crescent-shaped ridges oriented down-canyon. Combined with previous mapping of the upper end of Monterey Canyon by CSUMB, we now know that these features extend between 11 m and >1900 m water depths in Monterey Canyon. Repeat mapping shows that these bedforms change position between surveys. Sediment coring and experiments to track seafloor motion show that these changes occur during discrete mass transport events. In contrast the seafloor within the axis of Soquel Canyon is smooth. Chirp profiler data collected simultaneously with the multibeam data failed to resolve sub-bottom structures within the floor of Monterey Canyon, but show that the floor of Soquel Canyon contains up to15 m of horizontally layered fill. These differences are attributed to the processes within an active (e.g., Monterey) versus inactive (e.g., Soquel) submarine canyon and are hypothesized to be associated with the nature of the fill (cohesion-less sand and gravel versus cohesive fine sediments) within these canyons.

Lundsten, E.; Paull, C. K.; Caress, D. W.; Ussler, W.; Thomas, H.

2009-12-01

147

Particle fluxes dynamics in Blanes submarine canyon (Northwestern Mediterranean)  

NASA Astrophysics Data System (ADS)

Within the framework of the multidisciplinary RECS project and with the aim of describing the particle flux transfer from the continental shelf to the deep basin, an array of five mooring lines equipped with a total of five pairs of PPS3/3 sequential-sampling sediment traps and RCM-7/8 current meters were deployed 30 m above the bottom from March 2003 to March 2004 inside and outside the Blanes Canyon. One mooring line was located in the upper canyon at 600 m depth, one in the canyon axis at 1700 m depth and other two close to the canyon walls at 900 m depth. A fifth mooring line was deployed in the continental open slope at 1500 m water depth. The highest near-bottom downward particle flux (14.50 g m -2 d -1) was recorded at the trap located in the upper canyon (M1), where continental inputs associated with the presence of the Tordera River are most relevant. On the other hand, the downward fluxes (4.35 g m -2 d -1) in the canyon axis (M2) were of the same order as those found in the western flank (M3) of the canyon. Both values were clearly higher than the value (1.95 g m -2 d -1) recorded at the eastern canyon wall (M4). The open slope (M5) mass flux (5.42 mg m -2 d -1) recorded by the sediment trap located outside the canyon system was three orders of magnitude lower than the other values registered by the inner canyon stations. The relevance of our data is that it explains how the transport pathway in the canyon occurs through its western flank, where a more active and persistent current toward the open ocean was recorded over the entire year of the experiment. Off-shelf sediment transport along the canyon axis showed clear differences during the period of the study, with some important events leading to strong intensifications of the current coupled with large transport of particle fluxes to the deepest parts of the canyon. Such events are primarily related to increases in river discharge and the occurrence of strong storms and cascading events during the winter. In summary, in this study it is shown that the dynamics of the water masses and the currents in the study area convert the sharp western flank of the Blanes Canyon in a more active region that favors erosion processes than the eastern flank, which has a smoother topography and where the absence of erosional conditions yields to steadier sedimentary processes.

Zúñiga, Diana; Flexas, M. Mar; Sanchez-Vidal, Anna; Coenjaerts, Johan; Calafat, Antoni; Jordà, Gabriel; García-Orellana, Jordi; Puigdefàbregas, Joan; Canals, Miquel; Espino, Manuel; Sardà, Francesc; Company, Joan B.

2009-09-01

148

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

149

Workshop on recent research in the Valles caldera  

SciTech Connect

Over the last 5 years, there has been increased interest in the geology of the Jemez Mountains volcanic field, New Mexico. Of special interest is the Toledo-Valles caldera complex, which is targeted for research coring as part of the Continental Scientific Drilling Program. The general topics covered in this workshop were (1) hydrothermal systems and rock-water interactions, (2) volcanology and structural framework of the Jemez volcanic field, (3) determining the presence or absence of melt below the Valles caldera, and (4) deep coring and drilling technology. Separate abstracts were prepared for each presentation.

Heiken, G. (comp.)

1985-02-01

150

Atmospheric Fragmentation of the Canyon Diablo Meteoroid  

NASA Technical Reports Server (NTRS)

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.

Pierazzo, E.; Artemieva, N. A.

2005-01-01

151

History of the youngest members of the Valles Rhyolite, Valles caldera, New Mexico using ESR dating method  

SciTech Connect

The cooling history of the Valles caldera was studied by the electron spin resonance (ESR) dating method using Al and Ti centers in quartz grains which were separated from the youngest units of the Valles Rhyolite. The ESR apparent ages are much younger than fission track ages and {sup 39}Ar- {sup 40}Ar ages. Three possibilities are suggested, the first is that the ESR ages are real, the second is that ESR method did not work for these samples, and the third is that about 10--40 ka, the signal intensity was partially reduced by a thermal event such as proposed by Harrison et al. (1986). Research on the first and second possibilities is continuing. The third possibility might explain the difference between ESR ages and those by other methods (fission track and {sup 39}Ar- {sup 40}Ar). ESR dating has produced new insights regarding the history of the Valles caldera.

Ogoh, K.; Toyoda, S.; Ikeda, S.; Ikeya, M. (Osaka Univ., Toyonaka (Japan). Dept. of Physics); Goff, F. (Los Alamos National Lab., NM (United States))

1991-01-01

152

28. Fern Canyon (Meier 1979) This established RNA is on the San Dimas  

E-print Network

28. Fern Canyon (Meier 1979) Location This established RNA is on the San Dimas Experimental Forest of bigcone Douglas-fir (BDF) at Fern Canyon have burned recently (1975). Poor reproduction suggestsUSDA Forest Service General Technical Report PSW-GTR-188. 2004. 28. Fern Canyon Figure 58--Fern Canyon

Standiford, Richard B.

153

Parameter study of sound propagation between city canyons with a coupled FDTD-PE model  

Microsoft Academic Search

A parameter study is performed for the case of two-dimensional sound propagation from a (source) city canyon to a nearby, identical (receiver) city canyon. Focus was on sound pressure levels, relative to the free field, in the shielded canyon. An accurate and efficient coupled FDTD-PE model was applied, exploiting symmetry of the source and receiver canyon. With the proposed calculation

Timothy Van Renterghem; E. Salomons; D. Botteldooren

2006-01-01

154

Center is at Latitude 30 Degrees South, Longitude 90 Degrees  

NASA Technical Reports Server (NTRS)

Center of the orthographic projection is at latitude 30 degrees S., longitude 90 degrees. The top half is dominated by the Tharsis Montes volcanoes, the large Alba Patera shield volcano, the dark Chryse basin, and a vast canyon system, Valles Marineris. In the central part, a prominent physiographic feature, Thaumasia plateau, includes a complex array of small- and large-scale faults and ridges and ancient volcanoes. The large conspicuous Argyre basin, southeast of the Thaumasia plateau, contains a broad expanse of light-colored plains 800 km across. The permanent south polar ice cap is located near the bottom.

1994-01-01

155

Mars Exploration Curriculum  

NSDL National Science Digital Library

This series of modules integrates printable images of Mars into classroom activities. Four broad topics cover the exploration of Mars and the Pathfinder missions, the great Martian floods and the Pathfinder landing site, the canyon Valles Marineris, and water on Mars. Each topic has several discrete activities associated with it that can be used independently. There are supporting materials for teachers as well as background information on the images. There are two curriculum modules for grades 4-10, one for grades 6-12 and one for grades 9-12.

156

A Karst Connection model for Grand Canyon, Arizona, USA  

NASA Astrophysics Data System (ADS)

A new model for the connection of the eastern and western Grand Canyon is proposed that involves westward flow of Redwall karst aquifer water under the Kaibab arch along the steepest hydraulic gradient to discharge at a structural low in a headward-eroding protowestern Grand Canyon. A karst-aquifer hydrological connection was first established between the eastern and western Grand Canyon, then collapse, incision, and headward erosion of the canyon followed this subterranean route. This proposed model is based on what is happening today on the northern Marble Platform where the Redwall-Muav aquifer is still intact. The three sinkhole/caves Ah Hol Sah, Indian Pit, and Black Abyss provide vertical flow routes down to the Redwall karst aquifer, joining water discharging from the Kaiparowits hydrologic basin to the Colorado River along the Fence Springs system. Projecting this process back in time and spatially southward, we propose that at around 6 Ma a sinkhole or sinkholes existed at the confluence of the Colorado River with the Little Colorado River. Little Colorado River water, then flowing northward to an interior lake basin ("Glen Lake") in southern Utah, became pirated down this sinkhole(s), thus causing a reversal of drainage (barbed tributaries) in Marble Canyon. Headward erosion then proceeded up Marble and Little Colorado Canyons from the collapsing sinkhole, with Marble Canyon incision breaching Glen Lake at around 5.5 Ma. This effected the "final connection" and total integration of the Colorado River from Colorado to the Gulf of California.

Hill, C. A.; Eberz, N.; Buecher, R. H.

2008-03-01

157

Physical modeling of tidal resonance in a submarine canyon  

NASA Astrophysics Data System (ADS)

observations in submarine canyons poleward of 30° are usually dominated by the semidiurnal (M2) tidal frequency, which is superinertial at these latitudes. Observations from a submarine canyon at 44°N (the Gully, Nova Scotia) suggest that canyons can be dominated by the subinertial (K1) tidal frequency if length scales are correct for resonance of the K1 frequency. A model of the Gully was constructed in a tank on a rotating table and tidal currents generated to determine factors that influence resonance. Resonance curves were fit to measurements from the laboratory canyon for a range of stratifications, background rotation rates, and forcing amplitudes. Dense water was observed upwelling onto the continental shelf on either side of the laboratory canyon and traveled at least one canyon width along the shelf. Friction values measured in the laboratory were much higher than expected, probably due to upwelled water surging onto the shelf on each tidal cycle, similar to a tidal bore. By scaling observations from the laboratory to the ocean and assuming friction in the ocean is also affected by water traveling onto the shelf, a resonance curve for the ocean was created. Because of the broad resonance curve, the diurnal tide remains strong year round at the Gully, even as stratification at the shelf break changes. Dense water surging onto the shelf on tidal frequencies may affect friction and mixing at other nonresonant canyons.

Souëf, K. E.; Allen, S. E.

2014-02-01

158

Flushing of a buoyant pollutant from an urban canyon  

NASA Astrophysics Data System (ADS)

We examine the wind driven flushing of a negatively buoyant pollutant from an urban canyon. We examine the rate at which a fluid of buoyancy g' is removed from a two dimensional urban canyon of width W formed by two buildings of height H and square cross section. The flushing is driven by a wind flow, of mean velocity U, normal to the axis of the canyon. A previous study of flushing of a neutrally buoyant fluid by Caton et al. (2003) showed that the mean concentration decayed exponentially with time indicating a steady exchange of fluid between the canyon and the flow above and a uniformly well mixed canyon. However, for the case of a negatively buoyant pollutant, the fluid buoyancy will tend to suppress fluid exchange as additional work is required to lift the dense fluid up and out of the canyon. One would therefore expect that the flushing rate would be a function of the Froude number Fr=U/?g'H as well as the aspect ratio of the canyon H/W. In our experiments the canyon does not remain well mixed, but rather the buoyant fluid is skimmed off the top and the pollutant is etched away over time. We present experimental results for H/W=0.5 and 1 and 0.4canyon, Atmospheric Environment, 2003, 37, 693-702

Kaye, Nigel; Hunt, Gary; Syrios, Konstantinos

2008-11-01

159

Depositional environment and reservoir morphology of Canyon sandstones, Central Midland Basin, Texas  

E-print Network

- stone, Lucky Canyon field area. Circled wells indicate cores studied. Countour 1nterval 100 feet. 14 Sedimentary structures in Canyon "B" sandstones, Union Texas Petroleum Farmar 56-2, Rock Pen f1eld, Lucky Canyon area, Irion County, Texas... Munn 1-A. 44 19. Electric log characteristics, texture, composition, and bedding character of Canyon "8" sandstones, Union Texas Petroleum Farmar 56-2 45 20. Electric log characteristics, texture, compostion, and bedding character of Canyon "A...

Jones, James Winston

2012-06-07

160

Pollen taphonomy in a canyon stream  

NASA Astrophysics Data System (ADS)

Surface soil samples from the forested Chuska Mountains to the arid steppe of the Chinle Valley, Northeastern Arizona, show close correlation between modern pollen rain and vegetation. In contrast, modern alluvium is dominated by Pinus pollen throughout the canyon; it reflects neither the surrounding floodplain nor plateau vegetation. Pollen in surface soils is deposited by wind; pollen grains in alluvium are deposited by a stream as sedimentary particles. Clay-size particles correlate significantly with Pinus, Quercus, and Populus pollen. These pollen types settle, as clay does, in slack water. Chenopodiaceae- Amaranthus, Artemisia, other Tubuliflorae, and indeterminate pollen types correlate with sand-size particles, and are deposited by more turbulent water. Fluctuating pollen frequencies in alluvial deposits are related to sedimentology and do not reflect the local or regional vegetation where the sediments were deposited. Alluvial pollen is unreliable for reconstruction of paleoenvironments.

Fall, Patricia L.

1987-11-01

161

Davis Canyon air quality analysis: Revision 2  

SciTech Connect

Detailed supporting calculations, methodology and results of the air quality analysis performed for the Davis Canyon Environmental Assessment are presented in this report. In the absence of onsite meteorological data, data from Salt Wash, Utah, were used in the modeling. The US Environmental Protection Agency Industrial Source Complex (ISC) Model was used to model ground level and fugitive dust sources. The Valley Model was used to model NO/sub 2/ impacts from elevated sources on nearby elevated terrain. Maximum emission rates during site characterization and repository construction and operation are analyzed and reported. Predicted maximum ground level concentrations off site and at Canyonlands National Park are presented. Supporting calculations and computer model runs are presented in appendixes. Salt deposition around the site and impacts to air-quality-related values at Canyonlands, such as visibility, vegetation, and night skyglow are discussed, and results and supporting analyses are presented. 11 refs., 3 figs., 10 tabs.

Not Available

1985-11-01

162

Lynch Canyon combination thermal drive project. [Termination  

SciTech Connect

The following report provides a summary of the Lynch Canyon Thermal Drive Project. This demonstration project was begun in 1978 and terminated in 1980. The project originally was divided into four phases; Geologic Evaluation, Injectivity Test, Field Development Combined with Air-Water Injection, and a Project Review. Following the First Phase operations, which included drilling of four wells for geologic evaluation, a joint decision to cancel the project was made. The conditions which were thought to exist at the initiation of the project, would have provided an excellent opportunity to conduct a Pilot Combination Thermal Drive. However, potential problems which were discovered in the Phase One Operations significantly altered the economics of the project and removed the favorable conditions under which the project was begun.

Stair, J. R.

1980-11-01

163

Compositional range in the Canyon Diablo meteoroid  

NASA Astrophysics Data System (ADS)

The compositional range within the Canyon Diablo (CD) iron meteorites associated with the formation of the Meteor Crater (Arizona) was examined, using the INAA to analyze a set of CD samples consisting of nine irons collected within 7 km of the Meteor Crater, four Arizona IAB irons that were identified by Wasson (1968) as transported CD fragments, and irons from Las Vegas (Nevada) and Moab (Utah) that Buchwald (1975) suggested to be transported CD fragments. Results show that the irons named Helt Township, Idaho, Las Vegas, Mamaroneck, Moab, and Pulaski County are, most likely, mislabeled CD specimens. On the other hand, meteorites named Alexander County, Allan Hills A77283, Ashfork, Fairfield, and Rifle are identified as compositionally distinct independent falls.

Wasson, John T.; Ouyang, Xinwei

1990-11-01

164

The Controlled Flood in Grand Canyon  

NASA Astrophysics Data System (ADS)

The natural flow of almost every river in the United States has been modified to meet various socioeconomic goals—navigation, irrigation, power generation and flood control. The success of the dams and reservoirs built to achieve these goals has been accompanied by changes in the status of riverine resources downstream, a cause of growing environmental and ecological concern. For example, before Glen Canyon Dam was completed, the Colorado River transported large quantities of sediment in floods as large as 8500 m3/s. After the dam was closed in 1963, dam releases typically were less than the powerplant capacity of 890 m3/s and exhibited large daily flow fluctuations. The river carried little sediment. The daily fluctuations in flow eroded sand bars, and the smaller, controlled flow did not redeposit them. The clear, cold water resulted in increased aquatic productivity such that rainbow trout and other nonnative fishes thrived while most native species were lost or endangered.

Webb, Robert H.; Schmidt, John C.; Marzolf, G. Richard; Valdez, Richard A.

165

Compositional range in the Canyon Diablo meteoroid  

SciTech Connect

The Ir distribution in the IAB Canyon Diablo meteorites associated with the formation of Meteor Crater, Arizona, ranges from 2.1 to 2.5 {mu}g/g with peaks at 2.17 and 2.34 {mu}g/g. Only Ir, Ni, and Cu show appreciably more variance in the large set of specimens than observed within a single specimen. The Ir peaks may reflect random sampling of the large (40-100 m), fractionated meteoroid or the presence of two distinct metallic regions differing in composition. None of the other elements they determined show strong correlations with Ir; the Au range is strikingly small (1.5-1.6 {mu}g/g). The presence of chondritic silicates and high contents of planetary-type noble gases in IAB indicates that these solidified rapidly following melting, as expected if they originated as pools of impact-generated melt on a chondritic body. The absence of fractional crystallization trends is consistent with such a model. That 14 of 15 Ir contents fall into two peaks suggests the possibility that the meteoroid included two pools. The alternative that the distribution is continuous can be tested by the study of additional specimens; those from the crater rim are particularly important since these are largely shrapnel spalled from the trailing hemisphere of the meteoroid. Their studies show that the irons named Helt Township, Idaho, Las Vegas, Mamaroneck, Moab, and Pulaski County are probably mislabelled Canyon Diablo specimens; Jenny's Creek and Jenkins are also compositionally indistinguishable. Alexander County, Allan Hills A77283, Ashfork, Fairfield, and Rifle are compositionally distinct, independent falls.

Wasson, J.T.; Ouyang, Xinwei (Univ. of California, Los Angeles (USA))

1990-11-01

166

Chemical Characteristics of Ground-Water Discharge Along the South Rim of Grand Canyon in Grand Canyon National Park, Arizona, 2000-2001.  

National Technical Information Service (NTIS)

Springs flowing from the south rim of Grand Canyon are an important resource of Grand Canyon National Park, offering refuge to endemic and exotic terrestrial wildlife species and maintaining riparian areas. Population growth on the Coconino Plateau has in...

S. A. Monroe, R. C. Antweiler, R. J. Hart, H. E. Taylor, M. Truini

2004-01-01

167

Flow Focusing as a Control on the Width of Canyons Formed by Outburst Floods  

NASA Astrophysics Data System (ADS)

Spectacular canyons exist on the surfaces of Earth and Mars that were carved by ancient outburst megafloods. These canyons often have steep headwalls and were eroded into jointed rock. This suggests that canyon formation is driven by upstream retreat of waterfalls through toppling failure. Discharge reconstructions remain difficult, however, because we do not understand quantitatively the links between canyon formation and canyon morphology. Here we propose that the width of canyon headwalls is set by the shear stress distribution around the rim of the canyon, which governs the propensity for toppling failure, and that this distribution is controlled by focusing of flood water into the canyon head. To test this hypothesis, we performed a series of numerical simulations of 2-D, depth-averaged, turbulent flow using the hydraulic numerical modeling suite ANUGA Hydro and mapped the shear stresses along the rim of canyons of various geometries. The numerical simulations were designed to explore three dimensionless variables: the aspect ratio of the canyon (length normalized by width), the canyon width relative to the normal flow depth, and the Froude number. Preliminary results show that flow focusing at the head of a canyon can lead to heightened shear stresses there compared to the sides of the canyon. Flow focusing is most efficient for subcritical flows with large canyon aspect ratios, suggesting that canyons grow in all directions until they reach a critical length which depends on the Froude number only. Canyons longer than this critical length maintain a uniform width during canyon formation. Earth-analog canyons, where flood depths were constrained from previous paleo-hydraulic studies, show good agreement with our numerical predictions, suggesting that flow focusing may set the width of canyons during megafloods. Model results allow a link between process and form that will enable us to constrain better flood discharges on Earth and Mars, where other robust paleo-hydraulic tools are not available.

Lapotre, M. G.; Lamb, M. P.; Halliday, C. K.

2012-12-01

168

The Shape of Trail Canyon Alluvial Fan, Death Valley  

NASA Technical Reports Server (NTRS)

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.

Farr, Tom G.; Dohrenwend, John C.

1993-01-01

169

Valuing wildfire risk mitigation in Kyle Canyon, Nevada.  

E-print Network

??The federal government lists Kyle Canyon, Nevada, as an at-risk wildland-urban interface community. Stakeholders' attitudes and preferences about wildfires and mitigation options were assessed through… (more)

O'Brien, James P.

2005-01-01

170

76 FR 24516 - Glen Canyon Dam Adaptive Management Work Group  

Federal Register 2010, 2011, 2012, 2013

...the AMWG, a technical work group (TWG), a Grand Canyon...Bureau of Reclamation, Upper Colorado Regional Office, 125 South...Chief, Adaptive Management Group, Environmental Resources Division, Upper Colorado Regional Office, Salt...

2011-05-02

171

77 FR 43117 - Glen Canyon Dam Adaptive Management Work Group  

Federal Register 2010, 2011, 2012, 2013

...the AMWG, a technical work group (TWG), a Grand Canyon...Bureau of Reclamation, Upper Colorado Regional Office, 125 South...Chief, Adaptive Management Group, Environmental Resources Division, Upper Colorado Regional Office, Salt...

2012-07-23

172

Grand Canyon Glass Skywalk creates excitement and controversy  

NSDL National Science Digital Library

Skywalk at Grand Canyon making its debuthttp://www.azcentral.com/news/articles/0320grandcanyonskywalk20-ON.htmlGrand Canyon National Park [pdf]http://www.nps.gov/grca/Hualapai Tribehttp://www.itcaonline.com/tribes_hualapai.htmlASU Libraries: Native Americans Onlinehttp://www.asu.edu/lib/archives/links.htmGrand Canyon Skywalk [Macromedia Flash Player]http://www.grandcanyonskywalk.com/Over the millennia, the Grand Canyon has been the source of wonder and amazement as it was traversed first by indigenous people and a host of other individuals, including John Wesley Powell, who surveyed the area in 1869. This Tuesday saw the formal opening of a recent man-made addition to the rim of the Canyon that generated plenty of commentary and controversy months before it opened. The Grand Canyon Skywalk, which resembles a massive horseshoe, extends 70 feet beyond the canyon's edge. The Las Vegas developer, David Jin, created this project. Visitors to the Skywalk who pay $25 will get to look down through glass panels to the canyon floor some 4000 feet below, which could be both exhilarating and frightening, depending one one's temperament and tolerance for heights. The Hualapai Indians, who have aggressively defended the Skywalk as a form of effective economic development, approved the Skywalk and Sheri Yellowhawk who has been overseeing the project commented, "When we have so much poverty and so much unemployment, we have to do something." Other individuals and organizations have voiced strong concerns about the Skywalk, and Kieran Suckling, policy director for the Center for Biological Diversity is one of their number. In a recent interview, he commented "The tribe has repeatedly brought tacky, gross commercial ventures into the canyon, and it's inappropriate."The first link will take users to a well-written piece from Devika Bhat of the Times which comments on the opening of the Skywalk. The second link takes users to another piece on the Skywalk, offered courtesy of the Arizona Republic. Moving along, the third link leads to the very authoritative and informative National Park Service site dedicated to the natural history and geography of the Grand Canyon. The fourth link whisks users away to the Inter Tribal Council of Arizona's site on the Hualapai Tribe. The fifth link will take users to the Arizona State University Libraries' Native Americans Online site. Here, visitors can look over an extensive set of links that lead to a variety of online resources, such as digital collections and such. The final link leads to the official homepage of the Grand Canyon Skywalk, which is available in Korean, Japanese, Chinese, and English.

Grinnell, Max

173

Geology Fieldnotes: Glen Canyon National Recreation Area, Utah and Arizona  

NSDL National Science Digital Library

This Glen Canyon National Recreation Area site contains park geology information, photographs, related links, visitor information, multimedia resources, and teacher features (resources for teaching geology with National Park examples). The park geology section briefly discusses the Park's geologic history, structural geology, Navajo sandstone, and fossil beds. The park maps section contains a link to a features/relief map of Glen Canyon and the surrounding area, from the University of Texas at Austin Perry-Castaneda Library Map Collection.

174

The kinematics of debris flow transport down a canyon  

E-print Network

of the scholarly effor is concentrated elsewhere in the canyon system. Much work has been done on the initiation of debris flows (Terzaghi, 1950; Campbell, 1975; Keefer and Johnson, 1983; Pack, 1984; Jeppson, 1985; Ellen and Fleming, 1987; Mathewson and Santi..., 1987), the deposition of material by debris flows at the canyon mouth (Hooke, 1967; Olson, 1985; Keaton and Mathewson, 1987; Lips and Wieczorek, 1987), and on the properties of material while flowing (Johnson, 1970; Rodine, 1974; Johnson This thesis...

Santi, Paul M.

2012-06-07

175

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

USGS Publications Warehouse

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.

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

2010-01-01

176

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

...Flight Rules in the Vicinity of the Grand Canyon National Park, AZ Appendix to...Flight Rules in the Vicinity of Grand Canyon National Park, AZ Pt. 93...Flight Rules in the Vicinity of the Grand Canyon National Park, AZ...

2011-01-01

177

Land- and resource-use issues at the Valles Caldera  

SciTech Connect

The Valles Caldera possesses a wealth of resources from which various private parties as well as the public at large can benefit. Among the most significant of these are the geothermal energy resource and the natural resource. Wildlife, scenic, and recreational resources can be considered components of the natural resource. In addition, Native Americans in the area value the Valles Caldera as part of their religion. The use of land in the caldera to achieve the full benefits of one resource may adversely affect the value of other resources. Measures can be taken to minimize adverse affects and to maximize the benefits of all the varied resources within the caldera as equitably as possible. An understanding of present and potential land and resource uses in the Caldera, and who will benefit from these uses, can lead to the formulation of such measures.

Intemann, P.R.

1981-01-01

178

Search for Aqueous Minerals in Parana Valles, Mars  

NASA Astrophysics Data System (ADS)

Search for Aqueous Minerals in Parana Valles, Mars S. Talib, J.B. Dalton and J.M. Moore We have performed a compositional analysis of surface deposits in Parana Valles using a combination of Mars Observer Laser Altimeter (MOLA), Mars Observer Camera (MOC), Thermal Emission Spectrometer (TES) and Thermal Emission Imaging Subsystem (THEMIS) observations. Parana Valles lies within a well-defined basin in the southern highlands and contains a well-developed watershed drainage network (Barnhart et al., 2007). The strong evidence of hydrologic activity suggests that aqueously-derived minerals may be sufficiently abundant to be detected through orbital remote sensing. We examined MOLA observations to determine locations of smaller basins within Parana, where ponding and sedimentation may have occurred. Mosaics of MOC images were then examined to identify albedo differences which could indicate mineral deposits. THEMIS night-time thermal infrared mosaics were examined to identify regions of high thermal inertia, which may be swept clear of surface dust. Finally, image cubes from TES were compiled. The TES data were culled following the method of Stockstill et al. (2005) to eliminate orbital tracks of high atmospheric dust or water ice cloud composition. A Dust Cover Index (Ruff and Christensen 2002) was computed for TES data and used to reject observations obscured by high surface dust. Once the TES image cube had been reduced, regions of interest were defined based on the areas determined likely to contain minerals of aqueous origin based on the MOLA, MOC, and THEMIS observations. A linear spectral mixture model was then applied to these spectra using the Arizona State University Thermal Emission Spectral Library (Christensen et al., 2000) to estimate mineral abundances. We found that the surface mineralogy of Parana Valles is dominated by mixtures of phyllosilicates, feldspars, olivines and pyroxenes. This is consistent with chemically-weathered basaltic material.

Talib, Saveelah; Dalton, J. B.; Moore, J. M.

2007-10-01

179

The El Cajete Series, Valles caldera, New Mexico  

Microsoft Academic Search

Three rhyolite eruptive units totaling 3 km3 dense rock equivalent volume are the youngest products from the Valles caldera, New Mexico. These pyroclastic and effusive units, herein called the El Cajete Series, were erupted over an appreciable time period with Plinian and ignimbrite-forming activity preceding an effusive phase by a lengthy but indeterminable interval. New U-Th disequilibrium and published fission

S. Self; D. E. Kircher; J. A. Wolff

1988-01-01

180

Polymorphisms of ? - defensin genes in Valle del Belice dairy sheep  

Microsoft Academic Search

The aim of this work was to study ?-defensin 1 (SBD1) and ?-defensin 2 (SBD2) genes in Valle del Belice dairy sheep in order to identify polymorphisms that can be utilized as markers of the analyzed\\u000a genes, and search for the functional effects and roles of the identified polymorphisms (variation of the amino acid sequence\\u000a of the protein and stability

Giuseppina Monteleone; Davide Calascibetta; Mariangela Scaturro; Paola Galluzzo; Marisa Palmeri; Valentina Riggio; Baldassare Portolano

181

An Experimental Study of Submarine Canyon Evolution on Continental Slopes  

NASA Astrophysics Data System (ADS)

Submarine canyons define the morphology of many continental slopes and are conduits for the transport of sediment from shallow to deep water. Though the origin and evolution of submarine canyons is still debated, there is general agreement that sediment gravity flows play an important role. Here we present results from a simple, reduced-scale sandbox experiment designed to investigate how sediment gravity flows generate submarine canyons. In the experiments, gravity flows were modeled using either sediment-free or turbid saline currents. Unconfined flows were released onto an inclined bed of sand bounded on the downstream end by a movable floor that was incrementally lowered during the course of an experiment to produce an escarpment. This design was developed to represent the growth of relief across the continental slope. To monitor canyon evolution on the slope, we placed an overhead DSLR camera to record vivid time-lapse videos. At the end of each experimental stage we scanned the topography by imaging a series of submerged laser stripes, each projected from a motor-driven transverse laser sheet, onto a calibrated Cartesian coordinate system to produce high resolution bathymetry without draining the ambient water. In areas unaffected by the flows, we observe featureless, angle-of-repose submarine slopes formed by retrogressive breaching processes. In contrast, areas influenced by gravity flows cascading across the shelf break are deeply incised by submarine canyons with well-developed channel networks. Our results show that downslope gravity flows and submarine falling base level are both required to produce realistic canyon morphologies at laboratory scale. Though our mechanism for generating relief may be a rather crude analogue for the processes driving slope evolution, we hope our novel approach can stimulate new questions about the coevolution of canyons and slopes and motivate further experimental work to address them.

Lai, S. Y.; Gerber, T. P.; Amblas, D.

2013-12-01

182

Davis Canyon noise analysis: Revision 2  

SciTech Connect

A study was performed as part of the Civilian Radioactive Waste Management Program to quantify the level and effect of noise from the various major phases of development of the proposed potentially acceptable nuclear waste repository site at Davis Canyon, Utah. This report contains the results of a predictive noise level study for the site characterization, repository construction, and repository operational phases. Included herein are graphic representations of energy averaged sound levels, and of audibility levels representing impact zones expected during each phase. Sound levels from onsite and offsite activity including traffic on highways and railroad routes are presented in isopleth maps. A description of the Environmental Noise Prediction Model used for the study, the study basis and methodologies, and actual modeling data are provided. Noise and vibration levels from blasting are also predicted and evaluated. Protective noise criteria containing a margin of safety are used in relation to residences, schools, churches, noise-sensitive recreation areas, and noise-sensitive biological resources. Protective ground motion criteria for ruins and delicate rock formation in Canyonlands National Park and for human annoyance are used in the evaluation of blasting. The evaluations provide the basis for assessing the noise impacts from the related activities at the proposed repository. 45 refs., 21 figs., 15 tabs.

Not Available

1985-11-01

183

The bathypelagic community of Monterey Canyon  

NASA Astrophysics Data System (ADS)

We used a quiet, deep-diving remotely operated vehicle (ROV) to conduct oblique, quantitative video transects of the bathypelagic fauna at depths between 1000 and 3500 m at a site over the Monterey Submarine Canyon, in the eastern North Pacific off central California. Fifteen such dives were made over a two-year period. Analyses of the video data revealed a rich and diverse fauna dominated by gelatinous animals. In particular, the holopelagic polychaete Poeobius meseres was an important detritivore in the upper half of this depth range. As Poeobius abundance eventually declined with increasing depth, larvacean abundance increased. In contrast, the relative numbers of crustacean grazers, principally copepods and mysids, remained relatively constant with depth. Medusae were most abundant and most diverse among the gelatinous predators, which also included ctenophores, and siphonophores. Chaetognaths occurred chiefly in the upper half of the depth range. While there is considerable overlap, the bathypelagic fauna can be separated into upper (1000 to 2300 m) and lower (2400 to 3300 m) zones, as well as a distinct and populous benthic boundary layer. Within the overall bathypelagic community is a complex web of trophic links involving gelatinous predators that feed on both gelatinous and hard-bodied particle feeders, as well as on each other. The amount of organic carbon contained in this jelly web is substantial but its ecological fate is uncertain. The assessment of bathypelagic communities will be important for establishing baselines to conserve deep pelagic biodiversity within high-seas protected areas.

Robison, Bruce H.; Sherlock, Rob E.; Reisenbichler, Kim R.

2010-08-01

184

Continental Scientific Drilling Program: Valles Caldera, New Mexico  

SciTech Connect

The U.S. Continental Scientific Drilling Program attempts to develop a better understanding of the geologic and hydrologic mechanisms within the continental crust, under the auspices of an interagency group comprising the US Department of Energy, the National Science Foundation, and the U.S. Geological Survey. Ten years of research and drilling in the Valles caldera of northern New Mexico has provided a new understanding of volcanism and geothermal systems within a large caldera. Situated at the intersection of the Rio Grande rift and the Jemez volcanic lineament, the Valles caldera and Toledo calderas were formed during two massive eruptions 1.1 and 1.5 M a that vented approximately 300 to 400 km{sup 3} of high-silica rhyolitic tephra. The research at the Valles/Toledo caldera has provided more than 3000 m of corehole samples, which are stored in a repository in Grand Junction, Colorado, and are accessible to the public. This research has also helped support theories of mineral deposition within hydrothermal systems-hot water circulating through breccias, leaching elements from the rocks, and later depositing veins of economically valuable materials.

None

1993-01-01

185

Discovery of two new large submarine canyons in the Bering Sea  

USGS Publications Warehouse

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.

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

1984-01-01

186

Downstream effects of Glen Canyon Dam on the Colorado River in Grand Canyon: A review  

NASA Astrophysics Data System (ADS)

Glen Canyon Dam, completed in 1963, has altered geomorphic and ecological processes and resources of the Colorado River in Grand Canyon. Before the dam was completed, the river transported large quantities of sediment during spring floods as large as 8500 m3/s. After 1963, dam releases typically were less than 900 m3/s with large diurnal fluctuations and little sediment. The 2-yr peak discharge decreased by a factor of 2.5, resulting in aggraded rapids and a large increase in riparian vegetation. The clearwater releases from the dam eroded sand deposited on the bed and banks. Although pre-dam water temperatures varied seasonally, dam releases typically are about 8°C year round. Because of the clear, cold water and reduced flooding, post-dam aquatic productivity is considerably higher in the tailwater. Rainbow trout and other non-native fishes are now common, 3 native species have been extirpated, and the remaining species, including the endangered humpback chub, cannot successfully reproduce in the river.

Webb, R. H.; Wegner, D. L.; Andrews, E. D.; Valdez, R. A.; Patten, D. T.

187

Origin of Hot Creek Canyon, Long Valley caldera, California  

SciTech Connect

Hot Creek has eroded a canyon some thirty meters deep across the Hot Creek rhyolite flows located in the southeastern moat of Long Valley Caldera. Maloney (1987) showed that the canyon formed by headward erosion resulting from spring sapping along hydrothermally altered fractures in the rhyolite, and the capture of Mammoth Creek. This analysis ignored the continuing uplift of the central resurgent dome. Reid (1992) concluded that the downward erosion of the canyon must have kept pace with the uplift. Long Valley Lake occupied the caldera until 100,000 to 50,000 years before present. The elevation of the shoreline, determined by trigonometric leveling, is 2,166 m where the creek enters the canyon and 2,148 m on the downstream side of the rhyolite. The slope of the strand line is about equal to the stream gradient. The hill was lower and the stream gradient less at the time of stream capture. Rotational uplift increased the stream gradient which increased the rate of downward erosion and formed the V-shaped canyon

Maloney, N.J. (California State Univ., Fullerton, CA (United States). Dept. of Geological Sciences)

1993-04-01

188

75 FR 76650 - Proposed Modification of Class E Airspace; Bryce Canyon, UT  

Federal Register 2010, 2011, 2012, 2013

...This action proposes to modify Class E airspace at Bryce Canyon, UT to accommodate Area Navigation (RNAV) Global Positioning System (GPS) Standard Instrument Approach Procedures at Bryce Canyon Airport. The FAA is proposing this action...

2010-12-09

189

Canyon of the Ancients National Monument Amphibian and Reptile Brad Lambert  

E-print Network

Canyon of the Ancients National Monument Amphibian and Reptile Inventory by Brad Lambert March 2004................................................................................................................ 14 REPTILES OBSERVED IN 2003 SURVEYS Program to conduct field surveys for amphibians and reptiles in the Canyon of the Ancients National

190

75 FR 10308 - Fire Management Plan, Final Environmental Impact Statement, Record of Decision, Grand Canyon...  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF THE INTERIOR National Park Service Fire Management Plan, Final Environmental Impact...Environmental Impact Statement for the Fire Management Plan, Grand Canyon National...availability of the Record of Decision for the Fire Management Plan, Grand Canyon...

2010-03-05

191

78 FR 79436 - Boulder Canyon Project-Post-2017 Resource Pool  

Federal Register 2010, 2011, 2012, 2013

...Administration Boulder Canyon Project--Post-2017 Resource Pool AGENCY: Western Area...announces the Boulder Canyon Project (BCP) post-2017 resource pool marketing criteria...eligibility criteria and a resource pool (Post-2017 Resource Pool) to be...

2013-12-30

192

Live (stained) benthic foraminifera from the Cap-Ferret Canyon (Bay of Biscay, NE Atlantic): A comparison between the canyon axis and the surrounding areas  

NASA Astrophysics Data System (ADS)

Living (Rose Bengal stained) benthic foraminiferal faunas were investigated at 13 deep-sea stations sampled in the Cap-Ferret Canyon area (NE Atlantic). One station (151 m) is located on the continental shelf close to the canyon head. All other stations are located along 2 bathymetric transects: 7 sites along the canyon axis with depths ranging from 300 to 3000 m and 5 stations along the adjacent flank with depths ranging from 300 m to 2000 m. Sedimentological analyses indicate that the Cap-Ferret Canyon is at present inactive in terms of sediment gravity flow. Compared to stations on the adjacent flank, canyon-axis stations are generally characterised by shallow oxygen penetration depths, high diffusive oxygen uptakes (DOU) and high lipid contents. Higher mineralisation rates recorded in the canyon axis are likely due to a preferential focusing of labile organic matter in the canyon axis. Foraminiferal standing stocks do not exhibit any straightforward correlation with the different descriptors of organic matter available in the sediment. However, foraminiferal standing stock and diversity along the canyon axis are generally higher than on the adjacent flank. Canyon axis sites yield dominant species that are similar to those at adjacent flank and open slope stations located at comparable water depths. However, intermediate and deep infaunal species were only recorded in the lower canyon axis, where high amounts of organic matter were observed in deeper sediment layers. Finally, the faunal composition in the Cap-Ferret Canyon is different compared to the nearby Cap-Breton Canyon, where sediment gravity flows are active. The absence of pioneer species and the occurrence of highly specialized taxa are both consistent with the much more stable conditions in terms of hydro-sedimentary conditions prevailing in the Cap-Ferret Canyon.

Duros, P.; Fontanier, C.; Metzger, E.; Cesbron, F.; Deflandre, B.; Schmidt, S.; Buscail, R.; Zaragosi, S.; Kerhervé, P.; Rigaud, S.; Delgard, M.-L.; Jorissen, F. J.

2013-04-01

193

76 FR 54487 - Charter Renewal, Glen Canyon Dam Adaptive Management Work Group  

Federal Register 2010, 2011, 2012, 2013

...Reclamation Charter Renewal, Glen Canyon Dam Adaptive Management Work Group AGENCY...renewing the charter for the Glen Canyon Dam Adaptive Management Work Group. The purpose...respect to the operation of Glen Canyon Dam and the exercise of other authorities...

2011-09-01

194

Depth Distribution for the Order Cydippid (Phylum Ctenophora, Class Tentaculata) in the Monterey Submarine Canyon  

Microsoft Academic Search

This paper will discuss depth distribution analysis of cydippids in the Monterey Bay Submarine Canyon. Cydippids in the Monterey Canyon have been sighted at many different depths and areas. Since 1989, ten different cydippid species, including two new cydippids this year, were recorded on video using a remotely operated vehicle in ten sites within the Monterey Canyon. Because most of

Laura Dippold; Judith Connor; Nancy Jacobsen

195

Axial Channel Morphology Fill and Movement Within Submarine Canyons off California  

Microsoft Academic Search

Axial channels of seven submarine canyons off California have recently been investigated with ultrahigh resolution multibeam surveys. Vibracores collected from remotely operated vehicles (ROVs) provide ground truth data on the materials within the axis of six of these canyons. Acoustic beacons were used to track movement of the seafloor within the axis of Monterey Canyon. Multibeam bathymetry (0.15 m vertical

C. K. Paull; D. W. Caress; W. Ussler; E. Lundsten; H. Thomas

2008-01-01

196

Habitat associations of deep-water rockfishes in a submarine canyon: an example of  

E-print Network

(genus Se- bastes) and associated habitats in deep water was conducted in Soquel Sub- marine Canyon. There was remarkable concordance between some of the guilds identified in Soquel Canyon and the results of other habi- plified in Soquel Canyon. Rockfishes (Sebastes spp.) are quite speciose, dominate coastal benthic fish

197

Engineering Geologic Assessment of Risk to Visitors: Canyon Lake Gorge, Texas  

E-print Network

Presented here are the results of a study of geological hazards conducted in Canyon Lake Gorge of Central Texas. Canyon Lake Gorge formed in 2002 when the emergency spillway of Canyon Lake was overtopped. Since that time, the gorge has been opened...

Kolkmeier, Benjamin D.

2010-07-14

198

Thermal and air flow characteristics in a deep pedestrian canyon under hot weather conditions  

Microsoft Academic Search

The present paper reports the results of a specific experiment carried out in a deep pedestrian canyon in Athens, Greece. The air flow inside and outside the canyon as well as the air and surface temperatures inside the canyon are measured for a period of seven continuous days during the whole day and night period. The air flow characteristics inside

M. Santamouris; N. Papanikolaou; I. Koronakis; I. Livada; D. Asimakopoulos

1999-01-01

199

Biological and physical processes in and around Astoria submarine Canyon, Oregon, USA  

Microsoft Academic Search

Astoria Canyon represents the westernmost portion of the Columbia River drainage system, with the head of the canyon beginning just 16 km west of the mouth of the Columbia River along the northern Oregon and southern Washington coasts. During the summer of 2001, physical, chemical, and biological measurements in the canyon were taken to better understand the hydrodynamic setting of,

Keith L. Bosley; J. William Lavelle; Richard D. Brodeur; W. Waldo Wakefield; Robert L. Emmett; Edward T. Baker; Kara M. Rehmke

2004-01-01

200

Hydrodynamics and particle transport associated with a submarine canyon off Blanes (Spain), NW Mediterranean Sea  

Microsoft Academic Search

Particle transport rates were observed to be higher in a submarine canyon in the NW Mediterranean Sea than in areas surrounding the canyon. Velocity and particle profiles were used to reconstruct a three-dimensional (2-layer) grid of the flow field and resulting particle transport. Canyon topography enhanced both horizontal and downward transport of particles in an anticyclonic flow region over the

Timothy C. Granata; Beatriz Vidondo; Carlos M. Duarte; Maria Paola Satta; Marc Garcia

1999-01-01

201

Dense shelf water cascades in two northwestern Mediterranean submarine canyon heads during winters 2007 and 2008  

Microsoft Academic Search

Submarine canyons incised in continental margins are considered to be preferential pathways for the exchange of water and particles between the coastal area and the open sea. Hydrodynamics and sediment transport processes in submarine canyons depend upon several forcing conditions in the region such as general circulation, seafloor morphology and atmospheric regime. The off-shelf sediment transport trough submarine canyons, due

Marta Ribo; Pere Puig; Albert Palanques; Claudio Lo Iacono

2010-01-01

202

Gullying and erosion control at archaeological sites in Grand Canyon, Arizona  

Microsoft Academic Search

Gully erosion of cultural sites in Grand Canyon National Park is an urgent management problem that has intensified in recent decades, potentially related to the effects of Glen Canyon Dam. We studied 25 gullies at nine sites in Grand Canyon over the 2002 monsoon- erosion season to better understand the geomorphology of the gully erosion and the effec- tiveness of

Joel L. Pederson; Paul A. Petersen; Jennifer L. Dierker

2006-01-01

203

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

Microsoft Academic Search

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

M. Gaudin

2003-01-01

204

Two Middle Pleistocene Glacial-Interglacial Cycles from the Valle Grande, Jemez Mountains, northern New Mexico  

E-print Network

valley of the Valles Caldera in northern New Mexico, when a post-caldera eruption (South Mountain Alamos, NM 87544 ABSTRACT A long-lived middle Pleistocene lake formed in the Valle Grande, a large moat rhyolite) dammed the drainage out of the caldera. The deposits of this lake were cored in May 2004 (GLAD5

Anderson, R. Scott

205

CONTRASTING CRATONAL PROVENANCES FOR UPPER CRETACEOUS VALLE GROUP QUARTZITE CLASTS, BAJA CALIFORNIA  

E-print Network

97 CONTRASTING CRATONAL PROVENANCES FOR UPPER CRETACEOUS VALLE GROUP QUARTZITE CLASTS, BAJA batholith. Craton-derived quartzite clasts are a minor but ubiquitous component in Valle Group conglomerates the paleo-North American margin. Three strongly contrasting types of quartzite are recognized based

206

MAMÍFEROS DE LA RESERVA DEL VALLE DE LOS CIRIOS, BAJA CALIFORNIA, MÉXICO  

Microsoft Academic Search

El Valle de los Cirios es el área natural protegida más extensa de México. En la península de Baja California existe el mayor número de subespecies de mamíferos endémicos por área de distribución en todo el país, sin embargo, los trabajos mastofaunísticos realizados en la región son escasos. Por ende, el Valle de los Cirios no cuenta con algún estudio

Evelyn RIOS; Sergio TICUL ÁLVAREZ-CASTAÑEDA

2002-01-01

207

Reconstruction of the most recent volcanic eruptions from the Valles caldera, New Mexico  

Microsoft Academic Search

Products of the latest eruptions from the Valles caldera, New Mexico, consist of the El Cajete Pyroclastic Beds and Battleship Rock Ignimbrite, a sequence of pyroclastic fall and density current deposits erupted at ~55ka, capped by the later Banco Bonito Flow erupted at ~40ka, and collectively named the East Fork Member of the Valles Rhyolite. The stratigraphy of the East

J. A. Wolff; K. A. Brunstad; J. N. Gardner

2011-01-01

208

2 Grjota Valles and implications for flood sediment deposition on Mars 3 Devon M. Burr1  

E-print Network

2 Grjota� Valles and implications for flood sediment deposition on Mars 3 Devon M. Burr1 and Alex H Month 2006. 6 [1] Grjota� Valles is one of Mars' four Amazonian-aged, 7 fissure-headed, catastrophic unlikely on Mars and that their observance indicates 24 special paleohydraulic conditions. Citation: Burr

Perfect, Ed

209

Initial insights from 2.5D hydraulic modeling of floods in Athabasca Valles, Mars  

E-print Network

Initial insights from 2.5D hydraulic modeling of floods in Athabasca Valles, Mars L. P. Keszthelyi.5D hydraulic model to catastrophic floods on Mars. This model simulates flow over complex topography to Athabasca Valles, the youngest outflow channel on Mars, investigating previous bank-full discharge estimates

Perfect, Ed

210

Paleogene canyons of Tethyan margin and their hydrocarbon potential, Czechoslovakia  

SciTech Connect

Two Paleogene canyons buried below the Neogene foredeep and the Carpathian thrust belt in Southern Moravia have been outlined by drilling and seismic profiling. The features, as much as 12 km wide and over 1000 m deep, have been traced for 40 km. They are cut into Mesozoic and Paleozoic carbonate and clastic deposits and underlying Precambrian crystalline rocks. The sedimentary fill is made of late Eocene and early oligocene marine deposits, predominantly silty mudstones and siltstones. Sandstones and conglomerates are distributed mainly in the lower axial part of the valleys. Proximal and distal turbidites, grain-flow and debris-flow deposits have been identified in the fill. The common occurrence of slump folds, pebbly mudstones, and chaotic slump deposits indicate that mass movement played a significant role in sediment transport inside the canyons. The canyons are interpreted as being cut by rivers, then submerged and further developed by submarine processes. The organic rich mudstones of the canyon fill are significant source rocks (1-10% TOC). They reached the generative stage only after being tectonically buried below the Carpathian thrust belt in middle Miocene time. Channelized sandstones and proximal turbidities provide reservoirs of limited extent, although more substantial accumulations of sands are possible further downslope at the mouth of these canyons. Several oil fields have been discovered both within the canyon fill and the surrounding rocks. Similar Paleogene valleys may be present elsewhere along the ancient Tethyan margins buried below the Neogene foredeeps and frontal zones of the Alps and Carpathians. Their recognition could prove fruitful in the search for hydrocarbons.

Picha, F.J. (Chevron Overseas Petroleum Inc., San Ramon, CA (United States))

1991-03-01

211

A strontium isotope study of the VC-1 core hole and associated hydrothermal fluids and rocks from Valles Caldera, Jemez Mountains, New Mexico  

NASA Astrophysics Data System (ADS)

Chemical and strontium isotopic analyses have been performed on 10 geothermal waters from the Valles caldera/Jemez Mountain region, as well as 10 rock samples collected in the VC-1 scientific core hole. The 87Sr/86Sr values of other rocks sampled in the Jemez Mountains have also been used in this study to understand relations between the fluids and rocks of the volcanically driven geothermal system and the lateral outflow plume, discharging down the Jemez fault zone. The strontium content of groundwater is linked to the host rock composition, the aquifer temperature, and therefore the solubility of Sr-containing minerals. Low Sr concentrations in the fluid are found with a high temperature and/or volcanic host rocks, whereas high Sr concentrations are characteristic of a low temperature and/or a Paleozoic sedimentary aquifer. Important variations of the 87Sr/86Sr value in hydrothermal waters (0.70842-0.72193) are related to chemical composition, Sr content, and host rocks. For VC-1 core samples, the Sr isotopic ratios are also markedly variable (0.70459-0.75686), low for the Quaternary volcanics and high for the Paleozoic sedimentary rocks. The same observation is made for other Jemez Mountains rocks (0.70465-0.8163) with, in addition, high 87Sr/86Sr values for Precambrian crystalline rocks. A good correspondence is generally found between the waters and the reservoir rocks studied here, which indicates that isotopic equilibrium is rapidly attained. The following suite of hydraulically related fluids displays a progressive enrichment in radiogenic strontium: Baca wells (87Sr/86Sr = 0.7084-0.7094), VC-1 core hole at 483 m (0.7152-0.7154), Main Jemez Spring (0.7217), and Soda Dam (0.7219). This trend is associated with flow through Paleozoic rocks and with the length of the flow path from the center of Valles caldera (primary geothermal fluids) toward San Diego Canyon, along the Jemez fault zone (derivative waters).

Vuataz, FrançOis-D.; Goff, Fraser; Fouillac, Christian; Calvez, Jean-Yves

1988-06-01

212

Review of the Diablo Canyon probabilistic risk assessment  

SciTech Connect

This report details the review of the Diablo Canyon Probabilistic Risk Assessment (DCPRA). The study was performed under contract from the Probabilistic Risk Analysis Branch, Office of Nuclear Reactor Research, USNRC by Brookhaven National Laboratory. The DCPRA is a full scope Level I effort and although the review touched on all aspects of the PRA, the internal events and seismic events received the vast majority of the review effort. The report includes a number of independent systems analyses sensitivity studies, importance analyses as well as conclusions on the adequacy of the DCPRA for use in the Diablo Canyon Long Term Seismic Program.

Bozoki, G.E.; Fitzpatrick, R.G.; Bohn, M.P. [Sandia National Lab., Albuquerque, NM (United States); Sabek, M.G. [Atomic Energy Authority, Nuclear Regulatory and Safety Center, Cairo (Egypt); Ravindra, M.K.; Johnson, J.J. [EQE Engineering, San Francisco, CA (United States)

1994-08-01

213

Are amphitheater headed canyons indicative of a particular formative process?  

NASA Astrophysics Data System (ADS)

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 fluvial activity. In most cases, variability in amphitheater scale and location relates to the geometry of exposed strata, suggesting that contrasting, bimodal stratigraphy (i.e. strong, more permeable layer over weaker, less permeable layer) is required for amphitheater formation. This is particularly evident in Tarantula Mesa, where variations in the stratigraphy of the Tarantula Mesa Sandstone strongly influence canyon location and morphology. Amphitheaters form only where a thick, strong sandstone body is exposed in the headwaters of the drainage. Typical v-shaped canyon morphologies are seen nearby in otherwise identical drainages where the sandstone is interbedded with shale.

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

2012-12-01

214

Recent sediment studies refute Glen Canyon Dam hypothesis  

USGS Publications Warehouse

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.

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

2002-01-01

215

Surprise and Opportunity for Learning in Grand Canyon: the Glen Canyon Dam Adaptive Management Program  

NASA Astrophysics Data System (ADS)

With a focus on resources of the Colorado River ecosystem downstream of Glen Canyon Dam in Glen Canyon National Recreation Area (GCNRA) and Grand Canyon National Park (GCNP) of northern Arizona, the Glen Canyon Dam Adaptive Management Program has evaluated experimental flow and nonflow policy tests since 1990. Flow experiments have consisted of a variety of water releases from the dam within pre-existing annual downstream delivery agreements. The daily experimental dam operation, termed the Modified Low Fluctuating Flow (MLFF), implemented in 1996 to increase daily low flows and decrease daily peaks were intended to limit daily flow range to conserve tributary sand inputs and improve navigation among other objectives, including hydropower energy. Other flow tests have included controlled floods with some larger releases bypassing the dam's hydropower plant to rebuild and maintain eroded sandbars in GCNP. Experimental daily hydropeaking tests beyond MLFF have also been evaluated for managing the exotic recreational rainbow trout fishery in the dam's GCNRA tailwater. Experimental nonflow policies, such as physical removal of exotic fish below the tailwater, and experimental translocation of endangered native humpback chub from spawning habitats in the Little Colorado River (the largest natal origin site for chub in the basin) to other tributaries within GCNP have also been monitored. None of these large-scale field experiments has yet produced unambiguous results in terms of management prescriptions, owing to inadequate monitoring programs and confounding of treatment effects with effects of ongoing natural changes; most notably, a persistent warming of the river resulting from reduced storage in the dam's reservoir after 2003. But there have been several surprising results relative to predictions from models developed to identify monitoring needs and evaluate experimental design options at the start of the adaptive ecosystem assessment and management program in 1997. The repeated surprises were initially viewed with dismay by some managers and stakeholders who had unrealistic expectations about science and modeling to start with, yet actually represent scientific successes in terms of revealing new opportunities for developing better flow and non-flow policies. A new Long Term Experiment and Management Plan EIS (see URL) started in 2011, and co-led by the U.S. Department of the Interior's Bureau of Reclamation and the National Park Service, is underway and provides Colorado River managers, other stakeholders and the public a unique opportunity to refocus and weight resource objectives, conduct trade-off evaluations within the context of structured decision analyses, and identify key uncertainties with the goal of improving past experimental designs and monitoring strategies so as to take advantage of future learning opportunities over the next two decades. Perhaps the single greatest uncertainty now facing river managers is trying to anticipate how climate change and global warming will affect the supply of water from the Upper Colorado River Basin, Lake Powell storage that is known to control the river's thermal regime and native and nonnative fish interactions in GCNP, and the already highly-limited tributary sand supply below the dam from the Paria and Little Colorado Rivers required to manage sandbars along river shorelines.

Melis, T. S.; Walters, C. J.; Korman, J.

2013-12-01

216

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

USGS Publications Warehouse

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.

Sondossi, Hoda A.; Fairley, Helen C.

2014-01-01

217

Habitat characterization of deep-water coral reefs in La Gaviera Canyon (Avilés Canyon System, Cantabrian Sea)  

NASA Astrophysics Data System (ADS)

Surveys conducted at the complex Avilés Canyon System (southern Bay of Biscay) in order to identify vulnerable habitats and biological communities revealed the presence of noteworthy deep-water coral reefs in one of the tributaries of the system (La Gaviera Canyon). The aim of the present study is to determine why this deep-sea canyon provides suitable environmental conditions for corals to grow. This hanging canyon is characterized by an irregular U-shaped floor with two narrow differentiated flanks. Sand ripples and rocky outcrops structured in diverse W-E directed steps are observed on the canyon floor, suggesting intense hydrodynamic activity. Accordingly, high-frequency near-bottom current and thermal structure profiles showed that there occur strong shifts in currents/hydrography behaving as front-like features at each tidal cycle. These involve the sudden increase of along-axis velocities to over 50 cm/s and vertical velocities of over 5 cm/s in each tidal cycle associated with the passage of sharp thermal fronts and thermal inversions suggesting overturning. A year-long near-bottom current record showed events with near-bottom velocities well over 1 m/s lasting for several days. Three cold-water coral settings were distinguished: a dense coral reef located on stepped rocky bottoms of the eastern and western flanks, carbonate mounds (20-30 m high) located on the canyon floor, and a cluster of shallower water dead coral framework at the head sector of the canyon. Video and still images from a towed sled and ROV verified the presence of dropstones and rippled sand sheets surrounding the mounds and revealed changes in the coral population (alive or dead; total or patchy coverage) in coral reef and carbonate mound areas. The dominant species of the reef are Lophelia pertusa and Madrepora oculata, which considerably increase the habitat?s complexity and biodiversity in relation to other facies described in the canyon. The presence of living cold-water reefs is directly related to a high-energy environment at depths between 700 and 1200 m in the levels between the lower bound of Eastern North Atlantic Central Water (ENACW) and the core of Mediterranean Water (MW). Such level matches the water density range ??=27.35-27.65 kg m-3 which has been identified as limits for cold-water coral distribution in the North Atlantic.

Sánchez, Francisco; González-Pola, Cesar; Druet, María; García-Alegre, Ana; Acosta, Juan; Cristobo, Javier; Parra, Santiago; Ríos, Pilar; Altuna, Álvaro; Gómez-Ballesteros, María; Muñoz-Recio, Araceli; Rivera, Jesus; del Río, Guillermo Díaz

2014-08-01

218

Morphology, seismic characteristics and development of Cap Timiris Canyon, offshore Mauritania: A newly discovered canyon preserved-off a major arid climatic region  

Microsoft Academic Search

We employ a combined interpretation of Hydrosweep swath bathymetry and high resolution multi-channel seismic reflection data to investigate the development of Cap Timiris Canyon, a newly discovered submarine canyon offshore Mauritania. The dominantly V-shaped and deeply entrenched canyon exhibits many fluvial features including dendritic and meander patterns, cut-off loops and terraces, and is presently incising. Distal meander patterns, confined within

Andrew A. Antobreh; Sebastian Krastel

2006-01-01

219

General patterns of circulation, sediment fluxes and ecology of the Palamós (La Fonera) submarine canyon, northwestern Mediterranean  

Microsoft Academic Search

Currents, particle fluxes and ecology were studied in the Palamós submarine canyon (also known as the Fonera canyon), located in the northwestern Mediterranean. Seven mooring arrays equipped with current meters and sediment traps were deployed along the main canyon axis, on the canyon walls and on the adjacent slope. Additionally, local and regional hydrographic cruises were carried out. Current data

Albert Palanques; Emilio García-Ladona; Damià Gomis; Jacobo Martín; Marta Marcos; Ananda Pascual; Pere Puig; Josep-Maria Gili; Mikhail Emelianov; Sebastià Monserrat; Jorge Guillén; Joaquín Tintoré; Mariona Segura; Antoni Jordi; Simón Ruiz; Gotzon Basterretxea; Dolors Blasco; Francesc Pagès

2005-01-01

220

A Comparison of Techniques for Mapping the Distribution of Sediment on the Bed of the Colorado River in Grand Canyon  

Microsoft Academic Search

The Grand Canyon Monitoring and Research Center is charged with establishing and implementing monitoring projects to provide scientific information to the Glen Canyon Dam Adaptive Management Program (GCDAMP) on the effects of operating Glen Canyon Dam on the downstream resources of the Colorado River ecosystem. One primary resource of concern to the GCDAMP is fine-grained sediment. Glen Canyon Dam traps

E. Fuller; M. Kaplinski; D. M. Rubin

2004-01-01

221

Anomalous topography on the continental shelf around Hudson Canyon  

USGS Publications Warehouse

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.

Knebel, H. J.

1979-01-01

222

MODELLING AIR QUALITY IN STREET CANYONS: A REVIEW Sotiris Vardoulakisa  

E-print Network

in wind tunnels may also be used for investigating atmospheric processes within urban canyons have often been applied in combination with wind tunnel and/or field data to simulate small models; Computational Fluid Dynamics (CFD); Wind flow regimes; Traffic emissions Corresponding author

Paris-Sud XI, Université de

223

Carbonaceous aerosol particles from common vegetation in the Grand Canyon  

SciTech Connect

The problem of visibility reduction in the Grand Canyon due to fine organic aerosol particles in the atmosphere has become an area of increased environmental concern. Aerosol particles can be derived from many emission sources. In this report, we focus on identifying organic aerosols derived from common vegetation in the Grand Canyon. These aerosols are expected to be significant contributors to the total atmospheric organic aerosol content. Aerosol samples from living vegetation were collected by resuspension of surface wax and resin components liberated from the leaves of vegetation common to areas of the Grand Canyon. The samples were analyzed using high-resolution gas chromatography/mass spectrometry (GC/MS). Probable identification of compounds was made by comparison of sample spectra with National Institute of Standards and Technology (NIST) mass spectral references and positive identification of compounds was made when possible by comparison with authentic standards as well as NIST references. Using these references, we have been able to positively identify the presence of n-alkane and n-alkanoic acid homolog series in the surface waxes of the vegetation sampled. Several monoterpenes, sesquiterpenes, and diterpenes were identified also as possible biogenic aerosols which may contribute to the total organic aerosol abundance leading to visibility reduction in the Grand Canyon.

Hallock, K.A.; Mazurek, M.A. (Brookhaven National Lab., Upton, NY (United States)); Cass, G.R. (California Inst. of Tech., Pasadena, CA (United States). Dept. of Environmental Engineering Science)

1992-05-01

224

Thirty-five years at Pajarito Canyon Site  

SciTech Connect

A history of the research activities performed at the Pajarito Canyon Site from 1946 to 1981 is presented. Critical assemblies described include: the Topsy assembly; Lady Godiva; Godiva 2; Jezebel; Flattop; the Honeycomb assembly for Rover studies; Kiwi-TNT; PARKA reactor; Big Ten; and Plasma Cavity Assembly.

Paxton, H.C.

1981-05-01

225

Frequency and initiation of debris flows in Grand Canyon, Arizona  

NASA Astrophysics Data System (ADS)

Debris flows from 740 tributaries transport sediment into the Colorado River in Grand Canyon, Arizona, creating rapids that control its longitudinal profile. Debris flows mostly occur when runoff triggers failures in colluvium by a process termed "the fire hose effect." Debris flows originate from a limited number of geologic strata, almost exclusively shales or other clay-rich, fine-grained formations. Observations from 1984 through 2003 provide a 20 year record of all debris flows that reached the Colorado River in Grand Canyon, and repeat photography provides a 100 year record of debris flows from 147 tributaries. Observed frequencies are 5.1 events/year from 1984 to 2003, and historic frequencies are 5.0 events/year from 1890 to 1983. Logistic regression is used to model historic frequencies based on drainage basin parameters observed to control debris flow initiation and transport. From 5 to 7 of the 16 parameters evaluated are statistically significant, including drainage area, basin relief, and the height of and gradient below debris flow source areas, variables which reflect transport distance and potential energy. The aspect of the river channel, which at least partially reflects storm movement within the canyon, is also significant. Model results are used to calculate the probability of debris flow occurrence at the river over a century for all 740 tributaries. Owing to the variability of underlying geomorphic controls, the distribution of this probability is not uniform among tributaries of the Colorado River in Grand Canyon.

Griffiths, Peter G.; Webb, Robert H.; Melis, Theodore S.

2004-12-01

226

Natural variability in forests of the Grand Canyon, USA  

Microsoft Academic Search

Abstract Aim Compare contemporary with pre-fire-disruption forest structures, assessing the influence,of factors,that,caused,ecological,change,and,evaluating,remote,sites as relatively natural areas. Location,Grand,Canyon,National,Park contains,the largest never-harvested,and,long-

Peter Z. Fule; W. Wallace Covington; Margaret M. Moore; Thomas A. Heinlein; Amy E. M. Waltz

2002-01-01

227

Topography within the axial channels of Monterey and Soquel Canyons  

Microsoft Academic Search

Ultrahigh resolution surveys have been conducted that outline the topography and near seafloor structure within the axial channels of Monterey and Soquel Canyons. Multibeam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m at 50 m survey altitude) were collected using an autonomous underwater vehicle (AUV). An inertial navigation system combined with a doppler velocity sonar allows

E. Lundsten; C. K. Paull; D. W. Caress; W. Ussler; H. Thomas

2009-01-01

228

Wi-Fi + GPS for urban canyon positioning  

Microsoft Academic Search

GPS is now widely accepted as a reliable, available and accurate source of positioning, able to operate across the globe. However, it generally requires at least four satellites to be in view of the receiver, in order to resolve the three co-ordinates of the receiver, and the local receiver time offset. In indoor environments or urban canyons, this requirement can

Thomas GALLAGHER; Yong Khing TAN; Binghao LI; Andrew G DEMPSTER

2009-01-01

229

When did the Grand Canyon Begin to Form?  

NSDL National Science Digital Library

This post, originally published in the Connecting News with National Science Education Standards blog, deals with the findings suggesting the Grand Canyon is two to three times older than commonly believed. Ideas for engaging students in a thoughtful discussion about these research findings are provided.

Lefever, Mary; Hamilton, Carolyn

2008-03-14

230

Crisscrossing "Grand Canyon": Bridging the Gaps with Computer Conferencing.  

ERIC Educational Resources Information Center

Notes that Interdisciplinary Studies Program faculty at Wayne State University devised courses and assignments using computer conferencing to create a collaborative, democratic, and nonauthoritarian learning community. Discusses an assignment based on the film "Grand Canyon" that encouraged students to take on roles of their racial and gender…

Minock, Mary; Shor, Francis

1995-01-01

231

Grand Canyon Trekkers: School-Based Lunchtime Walking Program  

ERIC Educational Resources Information Center

The incidence of childhood overweight is especially troubling among low income Latino youth. Grand Canyon Trekkers (GCT) was implemented as a quasi-experimental study in 10 Title 1 elementary schools with a large Latino population to examine the effects of a 16-week structured walking program on components of health-related physical fitness: Body…

Hawthorne, Alisa; Shaibi, Gabriel; Gance-Cleveland, Bonnie; McFall, Sarah

2011-01-01

232

Grand Canyon Investigations: 131 Years in the Field  

USGS Multimedia Gallery

Staff at the USGS Central Region Library created two displays for an open-house in celebration of National Library Week, April, 2010. This display on USGS scientific investigtations of the Grand Canyon displays field records, historical photography,historical surveying equipment, and publications fr...

2010-05-17

233

Grand Canyon Investigations: 131 years in the field  

USGS Multimedia Gallery

Staff at the USGS Central Region Library created two displays for an open-house in celebration of National Library Week, April, 2010. This display on USGS scientific investigtations of the Grand Canyon displays field records, historical photography,historical surveying equipment, and publications fr...

2010-05-17

234

Small mammal study of Sandia Canyon, 1994 and 1995  

Microsoft Academic Search

A wide range of plant and wildlife species utilize water discharged from facilities at Los Alamos National Laboratory (LANL). The purpose of this study was to gather baseline data of small mammal populations and compare small mammal characteristics within three areas of Sandia Canyon, which receives outfall effluents from multiple sources. Three small mammal trapping webs were placed in the

K. Bennett; J. Biggs

1996-01-01

235

The Grand Canyon of the Yellowstone by Lucien Powell  

USGS Multimedia Gallery

This large (74" X 114.5") oil painting was done by Lucien W. Powell and is on loan to the Geological Survey from the Smithsonian National Museum of American Art. The title of the painting is The Grand Canyon of the Yellowstone. Object ID: USGS-575066...

2009-07-22

236

Small Mammal Sampling in Mortandad and Los Alamos Canyons, 2005  

SciTech Connect

As part of an ongoing ecological field investigation at Los Alamos National Laboratory, a study was conducted that compared measured contaminant concentrations in sediment to population parameters for small mammals in the Mortandad Canyon watershed. Mortandad Canyon and its tributary canyons have received contaminants from multiple solid waste management units and areas of concern since establishment of the Laboratory in the 1940s. The study included three reaches within Effluent and Mortandad canyons (E-1W, M-2W, and M-3) that had a spread in the concentrations of metals and radionuclides and included locations where polychlorinated biphenyls and perchlorate had been detected. A reference location, reach LA-BKG in upper Los Alamos Canyon, was also included in the study for comparison purposes. A small mammal study was initiated to assess whether potential adverse effects were evident in Mortandad Canyon due to the presence of contaminants, designated as contaminants of potential ecological concern, in the terrestrial media. Study sites, including the reference site, were sampled in late July/early August. Species diversity and the mean daily capture rate were the highest for E-1W reach and the lowest for the reference site. Species composition among the three reaches in Mortandad was similar with very little overlap with the reference canyon. Differences in species composition and diversity were most likely due to differences in habitat. Sex ratios, body weights, and reproductive status of small mammals were also evaluated. However, small sample sizes of some species within some sites affected the analysis. Ratios of males to females by species of each site (n = 5) were tested using a Chi-square analysis. No differences were detected. Where there was sufficient sample size, body weights of adult small mammals were compared between sites. No differences in body weights were found. Reproductive status of species appears to be similar across sites. However, sample size prevents a detailed examination of reproduction composition. Because of small sample size of some species and differences that might occur on a seasonal basis, additional sampling would need to be conducted to further evaluate sex ratios, body weights, and reproductive characteristics.

Kathy Bennett, Sherri Sherwood, and Rhonda Robinson

2006-08-15

237

Predicting velocities and turbulent momentum exchange in isolated street canyons  

NASA Astrophysics Data System (ADS)

A simplified way of studying the transport of mass and momentum through dense neighborhoods is to consider the flow field as a combination of a mainly horizontal flow along street canyons and a vertical flow into and out of street canyons. In this paper, we derive a simple, semi-analytical model for calculating the expected wind speeds in narrow, isolated, idealized street canyons of uniform height that are aligned with and at an angle to the wind through the introduction of a non-dimensional parameterization of the vertical turbulent exchange of horizontal momentum between the urban canopy layer (UCL) and the urban boundary layer (UBL). The model is closed and evaluated using computational fluid dynamics (CFD) in a generic way. The RMSE of the normalized bulk velocity in the street canyon in the direction of the freestream flow is 1.8 × 10-4, 2.3 × 10-2 and 9.4 × 10-2 for variations in façade roughness, aspect ratio and canyon orientation, respectively. We argue that there is a need for a fast, simple methodology to assess the impact of urban form on neighborhood microclimate, especially in dense neighborhoods, and specifically for use in the early phases of design. This methodology should be able to predict areas in a neighborhood that are prone to low wind speeds or weak mass and momentum exchange rates with the UBL above because these areas may be particularly susceptible to pollutant retention and the urban heat island (UHI) effect. Current methodologies are often inadequate for this purpose because they use computationally intensive techniques to solve for flow through a neighborhood and often require a strong technical background to support their use. The work in this paper addresses this problem for an idealized, narrow street canyon, and we discuss the need for parameterizations for urban form that are relevant to mass and momentum exchange rates to extend this model beyond a single street canyon. Finally, we discuss how this work could be further developed into generalized planning guidelines and incorporated into a comprehensive urban planning methodology that aims to passively mitigate the UHI effect and pollutant retention through the clever design of urban form.

Hall, Terianne C.; Britter, Rex E.; Norford, Leslie K.

2012-11-01

238

Thermal bioclimate in idealized urban street canyons in Campinas, Brazil  

NASA Astrophysics Data System (ADS)

Among several urban design parameters, the height-to-width ratio (H/W) and orientation are important parameters strongly affecting thermal conditions in cities. This paper quantifies changes in thermal comfort due to typical urban canyon configurations in Campinas, Brazil, and presents urban guidelines concerning H/W ratios and green spaces to adapt urban climate change. The study focuses on thermal comfort issues of humans in urban areas and performs evaluation in terms of physiologically equivalent temperature (PET), based on long-term data. Meteorological data of air temperature, relative humidity, wind speed and solar radiation over a 7-year period (2003-2010) were used. A 3D street canyon model was designed with RayMan Pro software to simulate the influence of urban configuration on urban thermal climate. The following configurations and setups were used. The model canyon was 500 m in length, with widths 9, 21, and 44 m. Its height varied in steps of 2.5 m, from 5 to 40 m. The canyon could be rotated in steps of 15°. The results show that urban design parameters such as width, height, and orientation modify thermal conditions within street canyons. A northeast-southwest orientation can reduce PET during daytime more than other scenarios. Forestry management and green areas are recommended to promote shade on pedestrian areas and on façades, and to improve bioclimate thermal stress, in particular for H/W ratio less than 0.5. The method and results can be applied by architects and urban planners interested in developing responsive guidelines for urban climate issues.

Abreu-Harbich, Loyde V.; Labaki, Lucila C.; Matzarakis, Andreas

2013-04-01

239

Thermal bioclimate in idealized urban street canyons in Campinas, Brazil  

NASA Astrophysics Data System (ADS)

Among several urban design parameters, the height-to-width ratio (H/W) and orientation are important parameters strongly affecting thermal conditions in cities. This paper quantifies changes in thermal comfort due to typical urban canyon configurations in Campinas, Brazil, and presents urban guidelines concerning H/W ratios and green spaces to adapt urban climate change. The study focuses on thermal comfort issues of humans in urban areas and performs evaluation in terms of physiologically equivalent temperature (PET), based on long-term data. Meteorological data of air temperature, relative humidity, wind speed and solar radiation over a 7-year period (2003-2010) were used. A 3D street canyon model was designed with RayMan Pro software to simulate the influence of urban configuration on urban thermal climate. The following configurations and setups were used. The model canyon was 500 m in length, with widths 9, 21, and 44 m. Its height varied in steps of 2.5 m, from 5 to 40 m. The canyon could be rotated in steps of 15°. The results show that urban design parameters such as width, height, and orientation modify thermal conditions within street canyons. A northeast-southwest orientation can reduce PET during daytime more than other scenarios. Forestry management and green areas are recommended to promote shade on pedestrian areas and on façades, and to improve bioclimate thermal stress, in particular for H/W ratio less than 0.5. The method and results can be applied by architects and urban planners interested in developing responsive guidelines for urban climate issues.

Abreu-Harbich, Loyde V.; Labaki, Lucila C.; Matzarakis, Andreas

2014-01-01

240

Morphotectonics and evolutionary controls on the Pearl River Canyon system, South China Sea  

NASA Astrophysics Data System (ADS)

The Pearl River Canyon system is a typical canyon system on the northern continental slope of the South China Sea, which has significant implications for hydrocarbon exploration. Through swath bathymetry in the canyon area combined with different types of seismic data, we have studied the morphotectonics and controlling factors of the canyon by analyzing its morphology and sedimentary structure, as well as the main features of the continental slope around the canyon. Results show that the Pearl River Canyon can be separated into three segments with different orientations. The upper reach is NW-oriented with a shallowly incised course, whereas the middle and lower reaches, that are located mainly in the Baiyun Sag, have a broad U-shape and have experienced consistent deposition. Seventeen deeply-cut canyons have developed in the slope north of the Baiyun Sag, playing an important role in the sedimentary processes of the middle and lower reaches of the Pearl River Canyon. These canyons display both asymmetrical V- and U-shapes along their lengths. Numerous buried channels can be identified below the modern canyons with unidirectionally migrating stacking patterns, suggesting that the canyons have experienced a cyclic evolution with several cut and fill phases of varying magnitude. These long established canyons, rather than the upper reach of the Pearl River Canyon, are the main conduits for the transport of terrigenous materials to the lower slope and abyssal basin during lowstand stage, and have contributed to the formation of vertically stacked deep-water fans in the middle reach. Canyon morphology is interpreted as a result of erosive sediment flows. The Pearl River Canyon and the 17 canyons in the slope area north of the Baiyun Sag probably have developed since the Miocene. Cenozoic tectonics, sea level change and sediment supply jointly control the morphology and sedimentary structure. The middle and lower reaches of the Pearl River Canyon developed on the paleo-terrain of the Baiyun Sag, which has been a persistently rapid depositional environment, receiving most of the materials transported via the canyons.

Ding, Weiwei; Li, Jiabiao; Li, Jun; Fang, Yinxia; Tang, Yong

2013-12-01

241

Holocene canyon activity under a combination of tidal and tectonic forcing  

NASA Astrophysics Data System (ADS)

The majority of submarine canyon systems that are active during sea level highstands are coupled to terrestrial or littoral sediment transport systems (e.g. high sediment-yield rivers, wave-base sediment disturbance). However, non-coupled canyon systems can also exhibit sedimentary activity. Characterising the nature, origin, and spatial and temporal influence of the processes responsible for this sedimentary activity is important to understand the extent of sediment and carbon transfer to the deep sea, the impact of sedimentary flows on biological colonisation and diversity, and the control of recent seafloor processes on canyon morphology. The Cook Strait canyon system, between the North and South islands of New Zealand, is a large (1800 km2), multi-branching, shelf-indenting canyon on an active subduction margin. The canyon comes within 1 km of the coast, but does not intercept fluvial or littoral sediment systems and is therefore defined as a non-terrestrially-coupled system. Sediment transport on the continental shelf, associated with a strong tidal stream, and seafloor disturbance related to numerous high-activity faults is known from previous studies. Little is known, however, about the rates of sedimentary activity in the canyon and the processes driving it. The canyon system therefore provides an excellent study area for understanding sediment transport in a non-coupled submarine canyon system. Analysis of EM300 multibeam bathymetry, gravity cores, 3.5 kHz seismic reflection profiles, camera and video transects and current meter data reveals a system where oceanographic (tidal) and tectonic (earthquake) processes are moving sediment from the continental shelf, through the upper canyon, and finally to the deep ocean. Sediment accumulation rates may reach several mm/yr in the upper canyons, with data suggesting minimum rates of 0.5 mm/yr. We demonstrate that tidal currents are sufficient to mobilise fine to medium sand around and within the upper canyon heads, and transported sediment is accumulating in upper canyon depocentres. Based on pseudo-static stability modelling, and supported by sediment core records, we estimate that earthquake triggered failure occurs approximately every 100 years. Lower canyon geomorphology indicates that failed material is being conveyed down the length of the canyon system to the deep ocean. Thus, while flushing rates may be low, the Cook Strait Canyon system can be considered to be an active sedimentary system during the current sea level high stand. The processes identified here are likely to be analogous to those occurring in many non-coupled shelf indenting canyons on tectonically active margins globally, and provide a framework within which the biological response to intermediate disturbance geomorphic processes in submarine canyons can be assessed.

Mountjoy, Joshu; Micallef, Aaron; Stevens, Craig; Stirling, Mark

2013-04-01

242

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

SciTech Connect

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 lower 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.

Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.; Becker, N.M.; Rodgers, J.C.; Hansen, W.R.

1994-12-01

243

Headless submarine canyons and fluid flow on the toe of the Cascadia accretionary complex  

USGS Publications Warehouse

Headless submarine canyons with steep headwalls and shallowly sloping floors occur on both the second and third landward vergent anticlines on the toe of the Cascadia accretionary complex off central Oregon (45 ??N, 125?? 30??W). In September 1993, we carried out a series of nine deep tow camera sled runs and nine ALVIN dives to examine the relationship between fluid venting, structure and canyon formation. We studied four canyons on the second and third landward vergent anticlines, as well as the apparently unfailed intercanyon regions along strike. All evidence of fluid expulsion is associated with the canyons; we found no evidence of fluid flow between canyons. Even though all fluid seeps are related to canyons, we did not find seeps in all canyons, and the location of the seeps within the canyons differed. On the landward facing limb of the second landward vergent anticline a robust cold seep community occurs at the canyon's inflection point. This seep is characterized by chemosynthetic vent clams, tube worms and extensive authigenic carbonate. Fluids for this seep may utilize high-permeability flow paths either parallel to bedding within the second thrust ridge or along the underlying thrust fault before leaking into the overriding section. Two seaward facing canyons on the third anticlinal ridge have vent clam communities near the canyon mouths at approximately the intersection between the anticlinal ridge and the adjacent forearc basin. No seeps were found along strike at the intersection of the slope basin and anticlinal ridge. We infer that the lack of seepage along strike and the presence of seeps in canyons may be related to fluid flow below the forearc basin/slope unconformity (overpressured by the impinging thrust fault to the west?) directed toward canyons at the surface.

Orange, D. L.; McAdoo, B. G.; Moore, J. C.; Tobin, H.; Screaton, E.; Chezar, H.; Lee, H.; Reid, M.; Vail, R.

1997-01-01

244

Seismic stratigraphy and development of Avon canyon in Benin (Dahomey) basin, southwestern Nigeria  

NASA Astrophysics Data System (ADS)

Interpretation of a grid of high resolution seismic profiles from the offshore eastern part of the Benin (Dahomey) basin in southwestern Nigeria area permitted the identification of cyclic events of cut and fill associated with the Avon canyon. Seismic stratigraphic analysis was carried out to evaluate the canyon morphology, origin and evolution. At least three generations of ancient submarine canyons and a newly formed submarine canyon have been identified. Seismic reflection parameters of the ancient canyons are characterized by transparent to slightly transparent, continuous to slightly discontinuous, high to moderate amplitude and parallel to sub-parallel reflections. Locally, high amplitude and chaotic reflections were observed. The reflection configurations consist of regular oblique, chaotic oblique, progradational and parallel to sub-parallel types. These seismic reflection characteristics are probably due to variable sedimentation processes within the canyons, which were affected by mass wasting. Canyon morphological features include step-wise and spoon-shaped wall development, deep valley incision, a V-shaped valley, similar orientation in the southeast direction, and simple to complex erosion features in the axial floor. The canyons have a composite origin, caused partly by lowering of the sea level probably associated with the formation of the Antarctic Ice Sheet about 30 Ma ago and partly by complex sedimentary processes. Regional correlation with geological ages using the reflectors show that the canyons cut through the Cretaceous and lower Tertiary sediments while the sedimentary infill of the canyon is predominantly Miocene and younger. Gravity-driven depositional processes, downward excavation by down slope sediment flows, mass wasting from the canyon walls and variation in terrigenous sediment supply have played significant roles in maintaining the canyons. These canyons were probably conduits for sediment transport to deep-waters in the Gulf of Guinea during their period of formation.

Olabode, S. O.; Adekoya, J. A.

2008-03-01

245

Restoring Anadromous Fish Habitat in Big Canyon Creek Watershed; Anadromous Fish Habitat Restoration in the Nichols Canyon Subwatershed, 1999 Annual Report.  

SciTech Connect

Nez Perce Soil & Water Conservation District (NPSWCD) undertook the Nichols Canyon Subwatershed Steelhead Trout Habitat Improvement Project in the spring of 1999. This Project is funded through a grant provided by the Bonneville Power Administration. The Project's purpose is to install and implement agricultural best management practices (BMPs) and riparian restorations to improve steelhead trout spawning and rearing habitat in the Nichols Canyon subwatershed of Big Canyon Creek. Improvements to spawning and rearing habitat in lower Big Canyon Creek tributaries will enhance natural production of the species in Big Canyon Creek and ultimately the Clearwater River. The following report is a summation of the activities undertaken by the NPSWCD in the first year of the project.

Koziol, Deb (Nez Perce Soil and Water Conservation District, Lewiston, ID)

2000-02-01

246

Deterministic Sampling Methods for Spheres and SO(3) Anna Yershova Steven M. LaValle  

E-print Network

Deterministic Sampling Methods for Spheres and SO(3) Anna Yershova Steven M. LaValle Dept of deterministic sampling methods. Although most existing motion planning methods currently use ran­ dom sampling

LaValle, Steven M.

247

Canyon air flow measurement utilizing ASME standard pitot tube arrays  

SciTech Connect

The Savannah River Site produces nuclear materials for national defense. In addition to nuclear reactors, the site has separation facilities for reprocessing irradiated nuclear fuel. The chemical separation of highly radioactive materials takes place by remote control in large buildings called canyons. Personnel in these buildings are shielded from radiation by thick concrete walls. Contaminated air is exhausted from the canyons and contaminants are removed by sand filters prior to release to the atmosphere through a stack. When these facilities were built on a crash basis in the early 1950's, inadequate means were provided for pressure and air flow measurement. This presentation describes the challenge we faced in retrofitting a highly radioactive, heavily shielded facility with instrumentation to provide this capability.

Moncrief, B.R.

1990-01-01

248

Numerical and experimental studies on flow and pollutant dispersion in urban street canyons  

NASA Astrophysics Data System (ADS)

In this study numerical simulations and water tank experiments were used to investigate the flow and pollutant dispersion in an urban street canyon. Two types of canyon geometry were tested. The studies indicate that in a step-up notch canyon (higher buildings on the downstream side of the canyon), the height and shape of the upstream lower buildings plays an important role in flow pattern and pollutant dispersion, while in a step-down notch canyon (lower buildings on the downstream side), the downstream lower buildings have little influence. The studies also show that the substitution of tall towers for parallelepiped buildings on one side of the canyon may enhance the street ventilation and decrease the pollutant concentration emitted by motor vehicles.

Jiang, Yujun; Liu, Huizhi; Sang, Jianguo; Zhang, Boyin

2007-02-01

249

The role of radiative-convective interaction in creating the microclimate of urban street canyons  

NASA Astrophysics Data System (ADS)

An approximate sky view factor (SVF) has been developed, which is capable of estimating the mean rate of net longwave radiant energy loss from urban street canyons. Reduced scale models of typical canyon geometries were used in outdoor tests to verify the predictions of radiant fluxes obtained using the proposed SVF. Air-surface temperature differences from the scale models are used together with hypothesized within-canyon airflow patterns to determine some quantitative characteristics of the wind field in canyons. Simple correlations are proposed for the relationship between mean in-canyon and pedestrian-level flow speeds on the one hand, and the ambient (above roof-level) wind speed on the other hand. As expected, the height/width ratio of a canyon controls the form and magnitude of the flow within.

Swaid, Hanna

1993-04-01

250

Vegetation and substrate on aeolian landscapes in the Colorado River corridor, Cataract Canyon, Utah  

USGS Publications Warehouse

Vegetation and substrate data presented in this report characterize ground cover on aeolian landscapes of the Colorado River corridor through Cataract Canyon, Utah, in Canyonlands National Park. The 27-km-long Cataract Canyon reach has undergone less anthropogenic alteration than other reaches of the mainstem Colorado River. Characterizing ecosystem parameters there provides a basis against which to evaluate future changes, such as those that could result from the further spread of nonnative plant species or increased visitor use. Upstream dams have less effect on the hydrology and sediment supply in Cataract Canyon compared with downstream reaches in Grand Canyon National Park. For this reason, comparison of these vegetation and substrate measurements with similar data from aeolian landscapes of Grand Canyon will help to resolve the effects of Glen Canyon Dam operations on the Colorado River corridor ecosystem.

Draut, Amy E.; Gillette, Elizabeth R.

2010-01-01

251

Application of a Lagrangian transport model to organo-mineral aggregates within the Nazaré canyon  

NASA Astrophysics Data System (ADS)

In this study, a hydrodynamic model was applied to the Nazaré submarine canyon with boundary forcing provided by an operational forecast model for the West Iberian coast. After validation, a Lagrangian transport model was coupled to the hydrodynamic model to study the transport patterns of the organo-mineral aggregates along the Nazaré canyon comparing three different classes of organo-mineral aggregates. The results showed that the transport in the canyon is neither constant, nor unidirectional and that there are preferential areas where suspended matter is resuspended, transported and deposited. The results showed that the transport of the larger size classes of organo-mineral aggregates is less pronounced, and that there is a decrease in the phytodetrital carbon flux along the canyon. The Nazaré canyon acts as depocenter of sedimentary organic matter and the canyon is not a conduit of organo-mineral aggregates to the deep sea.

Pando, S.; Juliano, M.; Garcia, R.; Mendes, P. A. de Jesus; Thomsen, L.

2013-01-01

252

The Dissolution of Desicooler Residues in H-Canyon Dissolvers  

SciTech Connect

A series of dissolution and characterization studies has been performed to determine if FB-Line residues stored in desicooler containers will dissolve using a modified H-Canyon processing flowsheet. Samples of desicooler materials were used to evaluate dissolving characteristics in the low-molar nitric acid solutions used in H-Canyon dissolvers. The selection for the H-Canyon dissolution of desicooler residues was based on their high-enriched uranium content and trace levels of plutonium. Test results showed that almost all of the enriched uranium will dissolve from the desicooler materials after extended boiling in one molar nitric acid solutions. The residue that contained uranium after completion of the extended boiling cycle consisted of brown solids that had agglomerated into large pieces and were floating on top of the dissolver solution. Addition of tenth molar fluoride to a three molar nitric acid solution containing boron did not dissolve remaining uranium from the brown solids. Only after boiling in an eight molar nitric acid-tenth molar fluoride solution without boron did remaining uranium and aluminum dissolve from the brown solids. The amount of uranium associated with brown solids would be approximately 1.4 percent of the total uranium content of the desicooler materials. The brown solids that remain in the First Uranium Cycle feed will accumulate at the organic/aqueous interface during solvent extraction operations. Most of the undissolved white residue that remained after extended boiling was aluminum oxide containing additional trace quantities of impurities. However, the presence of mercury used in H-Canyon dissolvers should complete the dissolution of these aluminum compounds.

Gray, J.H.

2003-06-23

253

A review of proposed Glen Canyon Dam interim operating criteria  

SciTech Connect

Three sets of interim operating criteria for Glen Canyon Dam on the Colorado River have been proposed for the period of November 1991, to the completion of the record of decision for the Glen Canyon Dam environmental impact statement (about 1993). These criteria set specific limits on dam releases, including maximum and minimum flows, up-ramp and down-ramp rates, and maximum daily fluctuation. Under the proposed interim criteria, all of these parameters would be reduced relative to historical operating criteria to protect downstream natural resources, including sediment deposits, threatened and endangered fishes, trout, the aquatic food base, and riparian plant communities. The scientific bases of the three sets of proposed operating criteria are evaluated in the present report:(1) criteria proposed by the Research/Scientific Group, associated with the Glen Canyon Environmental Studies (GCES); (2) criteria proposed state and federal officials charged with managing downstream resources; and (3) test criteria imposed from July 1991, to November 1991. Data from Phase 1 of the GCES and other sources established that the targeted natural resources are affected by dam operations, but the specific interim criteria chosen were not supported by any existing studies. It is unlikely that irreversible changes to any of the resources would occur over the interim period if historical operating criteria remained in place. It is likely that adoption of any of the sets of proposed interim operating criteria would reduce the levels of sediment transport and erosion below Glen Canyon Dam; however, these interim criteria could result in some adverse effects, including the accumulation of debris at tributary mouths, a shift of new high-water-zone vegetation into more flood-prone areas, and further declines in vegetation in the old high water zone.

LaGory, K.; Hlohowskyj, I.; Tomasko, D.; Hayse, J.; Durham, L.

1992-04-01

254

Pollution Sources Over the Grand Canyon and Canyonlands National Parks  

Microsoft Academic Search

To investigate pollution sources that are degrading the visibility of two national parks, Grand Canyon National Park, AZ, and Canyonlands National Park, UT, daily samples of total suspended particulates (TSP), PM2.5, trace gases, and organic compounds were collected in the two parks in the summer (July) of 2001 and winter (December-January) of 2001-2002. Factor analysis results show a number of

S. Huang; C. J. Popp; R. Arimoto; R. S. Martin

2003-01-01

255

Incision History of the Black Canyon of the Gunnison  

Microsoft Academic Search

The Gunnison River is the major tributary of the Colorado River that drains some of the highest topography of the Colorado Rocky Mountains. Paleo river profiles at 640ka, 10Ma, and ~35Ma provide benchmarks to understand the long-term incision history of the Black Canyon. Reconstruction of these paleo profiles is based on elevated bedrock straths and alluvial deposits that can be

M. Sandoval; K. E. Karlstrom; A. Aslan; E. Kirby; D. Granger

2006-01-01

256

LITTLE DOG AND PUP CANYONS ROADLESS AREA, NEW MEXICO.  

USGS Publications Warehouse

The Little Dog and Pup Canyons Roadless Area comprises about 41 sq mi along the precipitous west escarpment of the Guadalupe Mountains in southeastern New Mexico. On the basis of a mineral survey area is considered to have a portable potential for oil and (or) gas resources and little likelihood for the occurrence of other mineral or energy resources. Only the drilling of exploratory holes in or near the roadless area could conclusively determine its resource potential for oil and (or) gas.

Hayes, Philip T.; Bigsby, Philip R.

1984-01-01

257

Environmental geochemistry of the Bingham Canyon porphyry copper deposit, Utah  

Microsoft Academic Search

At the Bingham Canyon porphyry copper deposit, sulfide mineralization progresses outward from a low-grade core through the following general zones: (1) molybdenite, (2) chalcopyrite-bornite, (3) chalcopyrite-pyrite, (4) pyrite, and (5) sphalerite-galena. The low-grade core and the molybdenite zone are composed of net neutralizing rock and will generally not acidify when exposed to surface weathering conditions. The copper-bearing zones of the

Richard K. Borden

2003-01-01

258

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

USGS Publications Warehouse

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 subtle modification by Holocene processes active during the present sea-level high-stand.

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

2013-01-01

259

Origins of the 1996 controlled flood in Grand Canyon  

NASA Astrophysics Data System (ADS)

The March 1996 controlled flood in Grand Canyon resulted from a decade-long evolution in scientific thinking about the appropriate role of floods in management of the Colorado River in Grand Canyon. The flood was implemented after 5 consecutive years in which proposals to conduct a similar event were rejected; final implementation of the 1996 flood necessitated revision of the definition of the appropriate basin-wide runoff conditions that would trigger such a flood. The flood partly resulted from a multi-year effort to reform the Colorado River Storage Project Act that had culminated in passage of the Grand Canyon Protection Act in 1992. The flood itself consisted of a 4-day period of steady discharge of 227 m3/s, an 11-hr period of increasing discharge to a peak of 1274 m3/s that lasted for 7 days, a 45-hr period of recession, and a 4-day period of steady discharge at 227 m3/s. This event was partly a demonstration of the potential role of floods in regulated river management and also provided an opportunity for scientists to make measurements about physical and biological processes during flood conditions.

Schmidt, John C.; Andrews, Edmund D.; Wegner, David L.; Patten, Duncan T.; Marzolf, G. Richard; Moody, Thomas O.

260

Litter in submarine canyons off the west coast of Portugal  

NASA Astrophysics Data System (ADS)

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.

Mordecai, Gideon; Tyler, Paul A.; Masson, Douglas G.; Huvenne, Veerle A. I.

2011-12-01

261

Aquatic macroinvertebrates and water quality in Sandia Canyon  

SciTech Connect

In 1990, field studies of water quality and stream macroinvertebrate communities were initiated in Sandia Canyon at Los Alamos National Laboratory. The studies were designed to establish baseline data and to determine the effects of routine discharges of industrial and sanitary waste. Water quality measurements were taken and aquatic macroinvertebrates sampled at three permanent stations within the canyon. Two of the three sample stations are located where the stream regularly receives industrial and sanitary waste effluents. These stations exhibited a low diversity of macroinvertebrates and slightly degraded water quality. The last sample station, located approximately 0.4 km (0.25 mi) downstream from the nearest wastewater outfall, appears to be in a zone of recovery where water quality parameters more closely resemble those found in natural streams in the Los Alamos area. A large increase in macroinvertebrate diversity was also observed at the third station. These results indicate that effluents discharged into Sandia Canyon have a marked effect on water quality and aquatic macroinvertebrate communities.

Bennett, K.

1994-05-01

262

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

Microsoft Academic Search

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

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

2000-01-01

263

Facies control of Mississippian Porosity, Whitney Canyon-Carter Creek field, Wyoming Overthrust belt  

Microsoft Academic Search

Mississippian Mission Canyon carbonates are the most prolific Paleozoic reservoir in the Wyoming Overthrust belt. At Whitney Canyon-Carter Creek field, the Mission Canyon Formation holds recoverable reserves of 240 million bbl of oil equivalent. Production comes from a 350-ft (107 m) gross interval of shallow-water shelf carbonates. Capping the reservoir interval is a 300-ft (91 m) section of anhydrite and

Charles E. Bartberger

1985-01-01

264

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

USGS Publications Warehouse

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.

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

2002-01-01

265

DISSOLUTION OF FB-LINE METAL RESIDUES CONTAINING BERYLLIUM IN H-CANYON  

Microsoft Academic Search

Scrap materials containing plutonium (Pu) metal from FB-Line vaults are currently being dissolved in HB-Line for subsequent disposition through the H-Canyon facility. However, milestone and schedule commitments may require the dissolution of material containing Pu and beryllium (Be) metals in H-Canyon. To support this option, a flowsheet for dissolving Pu and Be metals in H-Canyon was demonstrated using a 4

T Rudisill; M Mark Crowder; M Michael Bronikowski

2005-01-01

266

Geological control of springs and seeps in the Farmington Canyon Complex, Davis County, Utah  

E-print Network

90 90 90 Q e~ N I 9WINI I d I. day rd 1999 Figure 39. Site L-4, Lightning Canyon. 57 LIGHTNING CANYON Site L-1 Topography and Outcrop C'a NQ 0 C. I. = 1. 5 meters Reference point ~ Spring Q Pegmatite Figure 40. Site L-t, Lightning... 90 90 90 Q e~ N I 9WINI I d I. day rd 1999 Figure 39. Site L-4, Lightning Canyon. 57 LIGHTNING CANYON Site L-1 Topography and Outcrop C'a NQ 0 C. I. = 1. 5 meters Reference point ~ Spring Q Pegmatite Figure 40. Site L-t, Lightning...

Skelton, Robyn Kaye

2012-06-07

267

UV Radiation in an Urban Canyon in Southeast Queensland  

NASA Astrophysics Data System (ADS)

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 throughout the day the intensity of erythemal UV measured in the city was significantly lower than that measured at the ASHRL site. On average the amount of erythemal UV measured in the urban canyon was approximately 33% of that measured at the ASHRL site. Based upon these findings we hope to conduct further study regarding UV exposure in the urban canyon.

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

2006-12-01

268

Cross faults in extensional settings: Stress triggering, displacement localization, and implications for the origin of blunt troughs at Valles  

E-print Network

] Motivated by conflicting interpretations concerning the origin of blunt terminations of troughs at Valles rather than collapse depressions. INDEX TERMS: 6225 Planetology: Solar System Objects: Mars; 8010

269

Restoring Anadromous Fish Habitat in Big Canyon Creek Watershed; Anadromous Fish Habitat Restoration in the Nichols Canyon Subwatershed, 2000 Annual Report.  

SciTech Connect

Nez Perce Soil & Water Conservation District (NPSWCD) undertook the Nichols Canyon Subwatershed Steelhead Trout Habitat Improvement Project in the spring of 1999 with funding from a grant through the Bonneville Power Administration. The Project's purpose is to install and implement agricultural best management practices (MBPS) and riparian restorations with the goal of improving steelhead trout spawning and rearing habitat in the subwatershed. Improvements to fish habitat in the Big Canyon Creek tributaries enhances natural production of the species in Big Canyon Creek and ultimately the Clearwater River. This report is a summation of the progress made by the NPSWCD in the Project's second year.

Koziol, Deb (Nez Perce Soil and Water Conservation District, Lewiston, ID)

2001-02-01

270

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

NASA Astrophysics Data System (ADS)

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 slope is inferred as the source of gravity flows driving canyon evolution. Canyon morphology is shown to be maintained over the course of more than one fall and rise in sea-level. Our model of canyon evolution is applicable to other passive margins (e.g. Argentine continental margin).

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

2013-04-01

271

Geomorphology of the Avilés Canyon System, Cantabrian Sea (Bay of Biscay)  

NASA Astrophysics Data System (ADS)

The Avilés Canyon System (ACS) is a complex, structurally-controlled canyon and valley system constituted by three main canyons of different morphostructural character. They are, from east to west: La Gaviera Canyon, El Corbiro Canyon and Avilés Canyon. In addition to this ACS, a new canyon has been surveyed: Navia Canyon. We present for the first time a high resolution multibeam map showing with great detail the morphological and structural complexity of this segment of the Cantabrian margin. ACS presents a tectonic imprint marked by NW-SE, NNE-SSW and E-W structures. The morphology of their reaches as well as their single mouth, in addition to some rock dredges in their major valleys, demonstrates active down-slope flushing. The continental shelf shows a flat, uniform slope with local and well defined rock outcrops south of Aviles Canyon head. Sedimentary zones are limited, showing thin unconsolidated sedimentary cover. Strong continental margin water dynamics avoid thicker sediment deposition, being littoral sedimentary dynamics responsible for transport to the canyons heads and conduit to the Biscay Abyssal plain. Biscay Abyssal Plain shows evidence of a strong westward current affecting the surveyed strip of this more than 10 km wide plain. Presence of two parallel deep sea channels, erosive scarps, and erosion of gully divides on the lower slope, may indicate that this is part of the distal fan at the termination of the large turbiditic system fed by Cap Ferret, Capbreton and other large canyons (Santander, Torrelavega, Lastres and Llanes) to the west of ACS.

Gómez-Ballesteros, María; Druet, María; Muñoz, Araceli; Arrese, Beatriz; Rivera, Jesús; Sánchez, Francisco; Cristobo, Javier; Parra, Santiago; García-Alegre, Ana; González-Pola, César; Gallastegui, Jorge; Acosta, Juan

2014-08-01

272

Submarine canyons: hotspots of benthic biomass and productivity in the deep sea  

PubMed Central

Submarine canyons are dramatic and widespread topographic features crossing continental and island margins in all oceans. Canyons can be sites of enhanced organic-matter flux and deposition through entrainment of coastal detrital export, dense shelf-water cascade, channelling of resuspended particulate material and focusing of sediment deposition. Despite their unusual ecological characteristics and global distribution along oceanic continental margins, only scattered information is available about the influence of submarine canyons on deep-sea ecosystem structure and productivity. Here, we show that deep-sea canyons such as the Kaikoura Canyon on the eastern New Zealand margin (42°01? S, 173°03? E) can sustain enormous biomasses of infaunal megabenthic invertebrates over large areas. Our reported biomass values are 100-fold higher than those previously reported for deep-sea (non-chemosynthetic) habitats below 500 m in the ocean. We also present evidence from deep-sea-towed camera images that areas in the canyon that have the extraordinary benthic biomass also harbour high abundances of macrourid (rattail) fishes likely to be feeding on the macro- and megabenthos. Bottom-trawl catch data also indicate that the Kaikoura Canyon has dramatically higher abundances of benthic-feeding fishes than adjacent slopes. Our results demonstrate that the Kaikoura Canyon is one of the most productive habitats described so far in the deep sea. A new global inventory suggests there are at least 660 submarine canyons worldwide, approximately 100 of which could be biomass hotspots similar to the Kaikoura Canyon. The importance of such deep-sea canyons as potential hotspots of production and commercial fisheries yields merits substantial further study. PMID:20444722

De Leo, Fabio C.; Smith, Craig R.; Rowden, Ashley A.; Bowden, David A.; Clark, Malcolm R.

2010-01-01

273

75 FR 19966 - Boulder Canyon Project-Post-2017 Application of the Energy Planning and Management Program Power...  

Federal Register 2010, 2011, 2012, 2013

...Power Administration Boulder Canyon Project--Post-2017 Application of the Energy Planning and Management Program Power Marketing Initiative...part 905) to the Boulder Canyon Project (BCP). This Federal Register...

2010-04-16

274

77 FR 38051 - Jones Canyon Hydro, LLC; Notice of Application for Amendment of Preliminary Permit Accepted for...  

Federal Register 2010, 2011, 2012, 2013

...28, 2011 for the Jones Canyon Pumped Storage Project. The proposed project would be a closed-loop pumped storage project located near Grass Valley...project from ``Jones Canyon Pumped Storage Project'' to ``Oregon...

2012-06-26

275

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

ERIC Educational Resources Information Center

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)

Travis, Tara

1997-01-01

276

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

PubMed Central

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

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

2014-01-01

277

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

PubMed

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 ((3)He) 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

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

2014-01-01

278

Glen Canyon Dam, Fluctuating Water Levels, and Riparian Breeding Birds: The Need for Management Compromise  

E-print Network

which existed diversity and equalled or exceeded them in avian under the pre-dam water regime consistedI ;'. I Glen Canyon Dam, Fluctuating Water Levels, and Riparian Breeding Birds: The Need.--Large water releases from Glen Canyon Dam in May and June are harmful to riparian breeding birds along

279

INCORPORATING SPATIAL AND TEMPORAL VARIATIONS OF ADVECTED MOISTURE IN THE CANYON AIR TEMPERATURE (CAT) MODEL  

Microsoft Academic Search

CAT (Canyon Air Temperature) is a parametric model that predicts site-specific air temperature in an urban street canyon for extended periods on the basis of data from a reference station in the region. A method is described for incorporating spatial and temporal variations in advected moisture, allowing application of the model with no prior knowledge of moisture availability in the

Evyatar Erell; Ingegard Eliasson; Sue Grimmond; Brian Offerle; Terry Williamson

2009-01-01

280

Dispersion and transfer of passive scalars in and above street canyons—Large-eddy simulations  

Microsoft Academic Search

This study applies a large-eddy simulation (LES) model to a street canyon in order to derive the fields of wind, turbulence, scalar concentration, concentration fluctuations, and scalar flux across the roof level. The wind blows at a right angle to the canyon axis and the emission is specified either as a line source with a constant emission rate along the

X.-M. Cai; J. F. Barlow; S. E. Belcher

2008-01-01

281

A reconnaissance of the Archean complex of the Granite Gorge, Grand Canyon, Arizona  

USGS Publications Warehouse

The field work upon which this article is based was done in March and April, 1914. From Garnet Canyon, near the west end of the Granite Gorge, the route followed the Tonto trail along the so-called lower plateau, or Tonto platform, to Red Canyon, at the east end of the Granite Gorge.

Noble, L. F.; Hunter, J. Fred

1917-01-01

282

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

Microsoft Academic Search

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

J. P Xu; Marlene Noble; Stephen L Eittreim; Leslie K Rosenfeld; Franklin B Schwing; Cynthia H Pilskaln

2002-01-01

283

36 CFR 7.53 - Black Canyon of the Gunnison National Monument.  

...Public Property 1 2014-07-01 2014-07-01 false Black Canyon of the Gunnison National Monument. 7.53 Section...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.53 Black Canyon of the Gunnison National Monument. (a)...

2014-07-01

284

Numerical Simulation of Recent Turbidity Currents in the Monterey Canyon System, Offshore California  

Microsoft Academic Search

The method of computational fluid dynamics (CFD) has been used, in the form of a 3D numerical model (Flow- 3D®), to perform a full-scale simulation of turbidity currents measured in December 2002 by three moorings in the Soquel and Monterey canyons. The model was verified by simulation of laboratory flows, and was upscaled to the Monterey Canyon system on the

S. Heimsund; J. Xu; W. Nemec

2007-01-01

285

Combined optic-flow and stereo-based navigation of urban canyons for a UAV  

Microsoft Academic Search

We present a novel vision-based technique for navigating an unmanned aerial vehicle (UAV) through urban canyons. Our technique relies on both optic flow and stereo vision information. We show that the combination of stereo and optic flow (stereo flow) is more effective at navigating urban canyons than either technique alone. Optic flow from a pair of sideways looking cameras is

Stefan Hrabar; Gaurav S. Sukhatme; Peter Corke; Kane Usher; Jonathan Roberts

2005-01-01

286

Geomorphic and hydrologic implications of the rapid incision of Afton Canyon, Mojave Desert, California  

NASA Astrophysics Data System (ADS)

Afton Canyon is a >150-m-deep canyon that formed as a result of overflow and drainage of Lake Manix, an ˜215 km2 late Wisconsin pluvial lake in the central Mojave Desert. Because the canyon age is within the range of conventional radiocarbon dating, it is possible to provide a time-based chronology of events and resultant landscape changes due to a >120 m base-level drop. Analysis of erosion volumes upstream of Afton Canyon and a review of public and private well logs downstream of the canyon mouth indicate that late Wisconsin surfaces are deeply buried downstream of Afton Canyon. Burial depths are ˜55 m at the mouth of Afton Canyon, 27 m in the Cronese basin, and 18 m at Crucero. The well logs also indicate that Soda Lake was far more areally extensive prior to late Wisconsin time. Stratigraphic and geomorphic evidence suggests that Afton Canyon was cut rapidly sometime after 14,230 ±1325 yr B.P. The rapid draining of Lake Manix and subsequent basin dissection have important implications for late Quaternary lake fluctuations in Death Valley, base-level changes and resultant alluvial-fan adjustments in the Cronese basin, the sand source for the Kelso Dunes, and the absence of old artifacts in the Cronese basin and the Mojave River wash region.

Meek, Norman

1989-01-01

287

Age and correlation of the unclassified dolomites of the Grand Canyon  

Microsoft Academic Search

Overlying the Muav Limestone in the Grand Canyon is an interval of dolomite that McKee (1945) described as unclassified Cambrian dolomites.'' These dolomites are unfossiliferous, and their age has remained uncertain. By measuring sections in the western Grand Canyon and in the Lake Mead region, the authors have been able to correlate members of the Muav Limestone and the overlying

V. S. Korolev; S. M. Rowland

1993-01-01

288

Spatial and temporal variability of meiobenthic density in the Blanes submarine canyon (NW Mediterranean)  

NASA Astrophysics Data System (ADS)

Meiofaunal density distribution was studied from 400 m to 1500 m depth inside Blanes submarine canyon (NW Mediterranean), and on the eastern open slope in autumn 2003 and spring 2004. Our multidisciplinary approach allowed to study the hydrodynamics and sedimentary processes in the Blanes Canyon that characterize it as highly heterogeneous environment. Inside the canyon area, particle fluxes were higher than on the slope area, increased from autumn to spring and mostly consisted of lithogenic material. Moreover the canyon’s locations experienced more intense bottoms’ currents and sediment disturbance, being reflected in a greater variability of meiobenthic densities, both between stations and sampling times than on the open slope. No clear trends (e.g. declining densities) associated with increasing depths were observed. Contrary in the open slope, current velocities were relatively lower compared with the canyon area and showed lower temporal variability. At the same time, the nutritional quality of the particle fluxes at deeper grounds were higher, probably allowing the meiofaunal densities not to change over time. In conclusion, the meiobenthos in our system apparently showed a higher temporal variability, inside the canyon area, strongly affected by particle fluxes or erosive and sediment-mixing processes linked to current modifications induced by the canyon topography.

Romano, C.; Coenjaerts, J.; Flexas, M. M.; Zúñiga, D.; Vanreusel, A.; Company, J. B.; Martin, D.

2013-11-01

289

Dispersal of natural and anthropogenic lead through submarine canyons at the Portuguese margin  

Microsoft Academic Search

Submarine canyons represent natural conduits for preferential transport of particulate material, including anthropogenic contaminants, from coastal zones directly to the deep sea. To assess related dispersal of natural and anthropogenic lead (Pb), we analyzed Pb concentrations and stable isotope ratios in surface sediments and sediment trap particulate material from the Portuguese margin Nazaré and Setúbal\\/Lisbon canyons. Geochemical data are integrated

T. O. Richter; H. C. de Stigter; W. Boer; C. C. Jesus; T. C. E. van Weering

2009-01-01

290

Identifying sources and processes controlling the sulphur cycle in the Canyon Creek watershed, Alberta, Canada  

Microsoft Academic Search

Sources and processes affecting the sulphur cycle in the Canyon Creek watershed in Alberta (Canada) were investigated. The catchment is important for water supply and recreational activities and is also a source of oil and natural gas. Water was collected from 10 locations along an 8 km stretch of Canyon Creek including three so-called sulphur pools, followed by the chemical and

Michael Nightingale; Bernhard Mayer

2012-01-01

291

Identifying sources and processes controlling the sulphur cycle in the Canyon Creek watershed, Alberta, Canada  

Microsoft Academic Search

Sources and processes affecting the sulphur cycle in the Canyon Creek watershed in Alberta (Canada) were investigated. The catchment is important for water supply and recreational activities and is also a source of oil and natural gas. Water was collected from 10 locations along an 8 km stretch of Canyon Creek including three so-called sulphur pools, followed by the chemical and

Michael Nightingale; Bernhard Mayer

2011-01-01

292

The Grand Canyon and Other Holes in the Ground. Natural Wonder Notebook.  

ERIC Educational Resources Information Center

The Grand Canyon, the natural wonder visited most often in the United States, is explored on foot, on burro, and by boat in this article. Learn about the canyon's different rock layers as well as its erosion, plant life, animal life, and water flow. (JM)

Markle, Sandra

1983-01-01

293

77 FR 19279 - Long Canyon Pumped Storage Project; Notice of Preliminary Permit Application Accepted for Filing...  

Federal Register 2010, 2011, 2012, 2013

...Project No. 14354-000] Long Canyon Pumped Storage Project; Notice...the feasibility of the Long Canyon Pumped Storage Project to be located near the town of Moab, Grand County, Utah. The [[Page...the project's powerhouse to Grand County Highway 279; (7)...

2012-03-30

294

36 CFR 7.53 - Black Canyon of the Gunnison National Monument.  

Code of Federal Regulations, 2010 CFR

...Public Property 1 2010-07-01 2010-07-01 false Black Canyon of the Gunnison National Monument. 7.53 Section...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.53 Black Canyon of the Gunnison National Monument. (a)...

2010-07-01

295

Small mammal study of Sandia Canyon, 1994 and 1995  

SciTech Connect

A wide range of plant and wildlife species utilize water discharged from facilities at Los Alamos National Laboratory (LANL). The purpose of this study was to gather baseline data of small mammal populations and compare small mammal characteristics within three areas of Sandia Canyon, which receives outfall effluents from multiple sources. Three small mammal trapping webs were placed in the upper portion of Sandia Canyon, the first two were centered in a cattail-dominated marsh with a ponderosa pine overstory and the third web was placed in a much drier transition area with a ponderosa pine overstory. Webs 1 and 2 had the highest species diversity indices with deer mice the most commonly captured species in all webs. However, at Web 1, voles, shrews, and harvest mice, species more commonly found in moist habitats, made up a much greater overall percentage (65.6%) than did deer mice and brush mice (34.5%). The highest densities and biomass of animals were found in Web 1 with a continual decrease in density estimates in each web downstream. There is no statistical difference between the mean body weights of deer mice and brush mice between sites. Mean body length was also determined not to be statistically different between the webs (GLM [deer mouse], F = 0.89, p = 0.4117; GLM [brush mouse], F = 2.49, p = 0.0999). Furthermore, no statistical difference between webs was found for the mean lean body masses of deer and brush mice (GLM [deer mouse], F = 2.54, p = 0.0838; GLM [brush mouse], F = 1.60, p = 0.2229). Additional monitoring studies should be conducted in Sandia Canyon so comparisons over time can be made. In addition, rodent tissues should be sampled for contaminants and then compared to background or control populations elsewhere at the Laboratory or at an off-site location.

Bennett, K.; Biggs, J.

1996-11-01

296

Aerodynamic effects of trees on pollutant concentration in street canyons.  

PubMed

This paper deals with aerodynamic effects of avenue-like tree planting on flow and traffic-originated pollutant dispersion in urban street canyons by means of wind tunnel experiments and numerical simulations. Several parameters affecting pedestrian level concentration are investigated, namely plant morphology, positioning and arrangement. We extend our previous work in this novel aspect of research to new configurations which comprise tree planting of different crown porosity and stand density, planted in two rows within a canyon of street width to building height ratio W/H=2 with perpendicular approaching wind. Sulfur hexafluoride was used as tracer gas to model the traffic emissions. Complementary to wind tunnel experiments, 3D numerical simulations were performed with the Computational Fluid Dynamics (CFD) code FLUENT using a Reynolds Stress turbulence closure for flow and the advection-diffusion method for concentration calculations. In the presence of trees, both measurements and simulations showed considerable larger pollutant concentrations near the leeward wall and slightly lower concentrations near the windward wall in comparison with the tree-less case. Tree stand density and crown porosity were found to be of minor importance in affecting pollutant concentration. On the other hand, the analysis indicated that W/H is a more crucial parameter. The larger the value of W/H the smaller is the effect of trees on pedestrian level concentration regardless of tree morphology and arrangement. A preliminary analysis of approaching flow velocities showed that at low wind speed the effect of trees on concentrations is worst than at higher speed. The investigations carried out in this work allowed us to set up an appropriate CFD modelling methodology for the study of the aerodynamic effects of tree planting in street canyons. The results obtained can be used by city planners for the design of tree planting in the urban environment with regard to air quality issues. PMID:19596394

Buccolieri, Riccardo; Gromke, Christof; Di Sabatino, Silvana; Ruck, Bodo

2009-09-15

297

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

E-print Network

gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles continental shelf, slope and rise between Cape Hatteras and Georges Bank (Andrews et al., 2013; Brothers et alGeomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid

ten Brink, Uri S.

298

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

...the Vicinity of the Grand Canyon National Park, AZ Appendix to Subpart U of Part 93...in the Vicinity of Grand Canyon National Park, AZ Pt. 93, Subpt. U, App. Appendix...the Vicinity of the Grand Canyon National Park, AZ...

2010-01-01

299

Incision History of the Black Canyon of the Gunnison  

NASA Astrophysics Data System (ADS)

The Gunnison River is the major tributary of the Colorado River that drains some of the highest topography of the Colorado Rocky Mountains. Paleo river profiles at 640ka, 10Ma, and ~35Ma provide benchmarks to understand the long-term incision history of the Black Canyon. Reconstruction of these paleo profiles is based on elevated bedrock straths and alluvial deposits that can be dated using the Lava Creek B ash (640 ka), Grand Mesa and associated basalts (10 Ma), and Oligocene ash flow tuffs (~35 Ma). Comparison of these to the modern profile offers insight into incision history. The modern long profile displays a distinct knickpoint located near the Painted Wall in the Black Canyon of the Gunnison National Park. This high-gradient reach (10-km-long) is partly explained by the Vernal Mesa Granite, but it traverses basement lithologies present above and below the knickpoint, suggesting that increased river gradient is not explained entirely by hard bedrock. Incision rates downstream of the knickpoint are higher (250-300 m/Ma over 640 ka and ~ 150 m/Ma over 10 Ma) in comparison to upstream rates (140 m/Ma over 640 ka and ~ 150 m/Ma over 10 Ma). The difference in incision rates across the knickpoint argue that this feature reflects transient adjustment of the fluvial system to baselevel lowering associated with downstream drainage reorganization. Incision rates in the nearby reaches of the Colorado River since 1-3 Ma are distinctly higher than those in the time periods of ~30 Ma- present and 10 Ma-present. This leads us to infer that rapid incision was not established in the Gunnison region until post ca. 3 Ma. A knickpoint similar to that seen in the modern profile is present in the reconstructed 640ka profile, reinforcing the transient character and implying upstream migration of the knickpoint of 25km in the past 640 ka. Projection of the ~ 640 ka river gravels in the abandoned Shinn- Bostwick tributary to its intersection with the Gunnison at Red Canyon is presently the best constraint on the age of incision; here, ~400m of its ~700m total depth in the Black Canyon has been incised in the last 640 ka. To refine these profiles and incision rates, new mapping and sampling for cosmogenic burial dating have been conducted on major terraces at the North Fork Gunnison-Gunnison River confluence, the Shinn-Bostwick Park, and Grizzley Creek. These will provide new dates, confirm tephrochronolgic associations, and refine preexisting data to further constrain incision history.

Sandoval, M.; Karlstrom, K. E.; Aslan, A.; Kirby, E.; Granger, D.

2006-12-01

300

Ordering Geologic Events and Interpreting Geologic History: The Grand Canyon  

NSDL National Science Digital Library

This activity is designed to help students recognize the connections among things like rock identification and map reading with the "story" that these things can tell us in terms of geologic history. Students have already learned about using observation to identify rocks and the principles of interpreting geologic cross-sections. The activity gives students practice in rock ID, topo map reading, geologic map reading and the aspects of geologic time. Students work with rock samples and a geologic map of the Grand Canyon to interpret a history for the area.

Wenner, Jennifer

301

Architecture of gas-hydrate-bearing sands from Walker Ridge 313, Green Canyon 955, and Alaminos Canyon 21: Northern deepwater Gulf of Mexico  

Microsoft Academic Search

Logging-while-drilling data acquired during the 2009 Gulf of Mexico (GoM) Gas Hydrate Joint Industry Project Leg II program combined with features observed in seismic data allow assessment of the depositional environment, geometry, and internal architecture of gas-hydrate-bearing sand reservoirs from three sites in the northern Gulf of Mexico (GoM): Walker Ridge 313, Alaminos Canyon 21, and Green Canyon 955. The

Ray Boswell; Matthew Frye; Dianna Shelander; William Shedd; Dan McConnell; Ann Cook

302

LaValle and Hutchinson IROS Ref: A1039 1 An ObjectiveBased Stochastic Framework for Manipulation Planning  

E-print Network

LaValle and Hutchinson IROS Ref: A­1039 1 An Objective­Based Stochastic Framework for Manipulation Planning Steven M. LaValle Seth A. Hutchinson lavalle@cs.uiuc.edu seth@cs.uiuc.edu Dept. of Electrical

LaValle, Steven M.

303

Apatite 4He/3He thermochronometry evidence for an ancient Grand Canyon, Colorado Plateau, USA  

NASA Astrophysics Data System (ADS)

The very existence of Grand Canyon inspires questions about why canyons are carved, how drainage systems and landscapes evolve, and how these processes relate to the elevation gain of plateaus. Yet when and why Grand Canyon was carved have been extraordinarily controversial for more than 150 years. Over the last several decades, the dominant view for the origin of the canyon is one of rapid incision at 5-6 Ma, when detritus derived from the upstream reaches of the Colorado River system appeared in Grand Wash Trough at the Colorado River's western exit from the Colorado Plateau. The absence of such diagnostic deposits prior to 6 Ma has been used to argue that Grand Canyon was not yet excavated (e.g., Karlstrom et al., 2008). However, a variety of data hint at a more ancient age for part or all of the canyon, and it has been proposed that a smaller drainage basin in largely carbonate lithologies could explain the absence of pre-6 Ma Colorado River clastics in Grand Wash Trough even if a significant Grand Canyon were present. Most recently, apatite (U-Th)/He (AHe) thermochronometry data from western Grand Canyon were used to infer excavation of this area to within several hundred meters of its modern depth by ca. 70 Ma (Wernicke, 2011), an interpretation in direct conflict with the young canyon model. The unexpected implications of the initial Grand Canyon AHe work motivated the apatite 4He/3He and U-Th zonation study presented here. Apatite 4He/3He thermochronometry provides information about the spatial distribution of radiogenic 4He in an apatite crystal that can better constrain a sample's cooling history. A key premise of AHe and 4He/3He spectra interpretation is that the He kinetic model used is accurate. We first investigate whether differing 4He/3He spectra for apatites of variable AHe date, radiation damage, and U-Th zonation from eastern Grand Canyon yield mutually consistent thermal history results using the RDAAM kinetic model, which must be true if the system behaves as we anticipate. The eastern Grand Canyon 4He/3He spectra are in excellent quantitative agreement and yield a multi-phase cooling history consistent with previously published AHe data. With this validation of the radiation damage He kinetic model, we turn our attention to a similar dataset from western Grand Canyon. We find that the apatite 4He/3He and AHe data provide evidence that this segment of the canyon was excavated to within a few hundred m of modern depths by ca. 70 Ma, more than 60 m.y. earlier than generally believed. The data do not detect the strong late Tertiary cooling phase predicted by the prevailing model in which the entire canyon was carved in the last 5-6 Ma. Although the results presented here challenge the young canyon view, at present we do not see a reasonable alternative explanation for the data, and argue that any canyon model should attempt to account for these results in some viable form. No existing data refute the more ancient age for the canyon implied by these results. An ancient Grand Canyon would have important implications for the evolution of topography, landscapes, hydrology, and tectonism in the North American Cordillera.

Flowers, R. M.; Farley, K. A.

2012-12-01

304

Geologic map of the Paintbrush Canyon Area, Yucca Mountain, Nevada  

SciTech Connect

This geologic map is produced to support site characterization studies of Yucca Mountain, Nevada, site of a potential nuclear waste storage facility. The area encompassed by this map lies between Yucca Wash and Fortymile Canyon, northeast of Yucca Mountain. It is on the southern flank of the Timber Mountain caldera complex within the southwest Nevada volcanic field. Miocene tuffs and lavas of the Calico Hills Formation, the Paintbrush Group, and the Timber Mountain Group crop out in the area of this map. The source vents of the tuff cones and lava domes commonly are located beneath the thickest deposits of pyroclastic ejecta and lava flows. The rocks within the mapped area have been deformed by north- and northwest-striking, dominantly west-dipping normal faults and a few east-dipping normal faults. Faults commonly are characterized by well developed fault scarps, thick breccia zones, and hanging-wall grabens. Latest movement as preserved by slickensides on west-dipping fault scarps is oblique down towards the southwest. Two of these faults, the Paintbrush Canyon fault and the Bow Ridge fault, are major block-bounding faults here and to the south at Yucca Mountain. Offset of stratigraphic units across faults indicates that faulting occurred throughout the time these volcanic units were deposited.

Dickerson, R.P. [Geological Survey, Denver, CO (United States); Drake, R.M. II [Pacific Western Technologies, Ltd., Lakewood, CO (United States)

1998-11-01

305

Baltimore Canyon Trough, a clastic-carbonate system  

SciTech Connect

Baltimore Canyon Trough is similar in age, architecture, and sedimentary framework to neighboring marginal basins offshore from eastern North America. The other basins are the Scotian and Georges Bank basins and the Carolina Trough. All contain a Jurassic-earliest Cretaceous clastic-carbonate sedimentary section composed of terrigenous basin fill and a shallow-water limestone platform. In Baltimore Canyon Trough, the platform is believed to be over 10 km thick. Upward through the Jurassic System, the platform progrades seaward and narrows. The platform top is earliest Cretaceous (Berriasian) and only about 5-15 km wide. Width of the base is indeterminate but apparently much wider. At the seaward edge of the platform is a limestone buildup and reef complex that consists of bioclastic wackestones, packstones, grainstones, and sponge-stromatoporoid-algal bindstones. Foreslope deposits are thrombolitic stromatactis-pelletal carbonate mudstones. Landward of the buildup, the platform contains numerous siliciclastic interbeds, consisting of mostly calcareous shale and siltstone with inertinite. The calciclastic lime mudstone beds of the platform contain terrigenous siliciclasts and kerogens. All units are oxidized and show considerable sedimentary reworking. Through the Jurassic System and into the Cretaceous, terrigenous clastic sediments became increasingly dominant in the basin and erosional-depositional cycles continually reworked carbonate, as well as siliciclastic, units.

Edson, G.M. (Minerals Management Service, Herndon, VA (USA))

1990-05-01

306

Mollusk Survey in the Snake River, Hells Canyon, USA  

NASA Astrophysics Data System (ADS)

We conducted surveys and several experiments on mollusks, focusing on listed, rare, or sensitive species, in reservoirs, tributaries and main stem of the Snake River in Hells Canyon Idaho and Oregon, USA. The most important result of this study was documentation of the undescribed Taylorconcha sp. throughout the Snake River in Hells Canyon, although we did not find Taylorconcha sp. within 12 miles downstream of HCD, most likely due to river armoring. Additional results include: 1) the mollusk community was similar throughout the Snake River, except where the Salmon River entered the Snake River; 2) Taylorconcha sp. abundance was directly related to the abundance of Potamopyrgus antipodarum, a highly invasive snail, and with moderate abundance of detritus; 3) hand picking cobbles was more efficient than suction dredging for snails and limpets but not for bivalves, 4) the most abundant mollusks were two invasive species, P. antipodarum and Corbicula fluminea and; 5) only one live small colony of native Gonidea angulata (Unionidae) and no live Anodonta californiensis (Unionidae) were found in the survey.

Lester, G. T.; Falter, C. M.; Myers, R.; Richards, D. C.

2005-05-01

307

Field trip guide to the Valles Caldera and its geothermal systems  

SciTech Connect

This field trip guide has been compiled from extensive field trips led at Los Alamos National Laboratory during the past six years. The original version of this guide was designed to augment a workshop on the Valles Caldera for the Continental Scientific Drilling Program (CSDP). This workshop was held at Los Alamos, New Mexico, 5-7 October 1982. More stops were added to this guide to display the volcanic and geothermal features at the Valles Caldera. The trip covers about 90 miles (one way) and takes two days to complete; however, those who wish to compress the trip into one day are advised to use the designated stops listed in the Introduction. Valles Caldera and vicinity comprise both one of the most exciting geothermal areas in the United States and one of the best preserved Quaternary caldera complexes in the world.

Goff, F.E.; Bolivar, S.L.

1983-12-01

308

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

NASA Astrophysics Data System (ADS)

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 impacts show that seafloor disturbance by benthic fishing is mainly attributable to trawling in the Gulf of Lion and to long lines where rocky substrates are present. The bauxite residue (red mud) expelled in the Cassidaigne canyon was seen to prevent fauna from settling at the bottom of the canyon and it covered much of the flanks. Litter was present in all of the canyons and especially in considerable quantities in the Ligurian Sea, where the heads of the canyons are closer to the coast. Three Marine Protected Areas and one fishing area with restricted access have recently been established and should permit the preservation of these deep ecosystems.

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

2014-06-01

309

Dispersal of natural and anthropogenic lead through submarine canyons at the Portuguese margin  

NASA Astrophysics Data System (ADS)

Submarine canyons represent natural conduits for preferential transport of particulate material, including anthropogenic contaminants, from coastal zones directly to the deep sea. To assess related dispersal of natural and anthropogenic lead (Pb), we analyzed Pb concentrations and stable isotope ratios in surface sediments and sediment trap particulate material from the Portuguese margin Nazaré and Setúbal/Lisbon canyons. Geochemical data are integrated with previously obtained data on near-bottom hydrodynamics and processes and pathways of sediment transport. The two canyon systems are located in close geographic proximity to each other, but represent contrasting settings in terms of sediment input and down-canyon sediment transport processes. Concentration-isotope diagrams and three-isotope plots ( 206Pb/ 207Pb vs. 208Pb/ 206Pb) suggest binary mixing between natural and anthropogenic end members. The inferred isotopic signature of pollutant Pb ( 206Pb/ 207Pb=1.143 [1.134-1.149, 95% confidence interval]) is most consistent with industrial Pb; ongoing influence from gasoline Pb additives is at most of minor importance. Two proposed natural end members most likely bracket the isotopic signature of natural Pb. Accordingly, binary mixing calculations indicate that on average 20-45% vs. 35-55% of total Pb is derived from anthropogenic sources in the Nazaré and Setúbal-Lisbon canyon systems, respectively. Enhanced anthropogenic influence in the latter area is consistent with its proximity to heavily populated and industrialized areas and with sediment input from the Tagus and Sado rivers, potential major carriers of pollutant particles. In both canyon systems, the anthropogenic component generally decreases with increasing water depth. Isotopic signatures of sediment trap particulate material are generally consistent with surface sediment data at similar water depth, but show large variability in the upper Nazaré canyon and major deviations from surface sediments in the lower canyon. In the lower canyon, Pb isotopic ratios of sediment trap particulate material mostly reflect low pelagic fluxes from the overlying water column, whereas surface sediment signatures are dominated by episodic down-canyon mass transport events. Such gravity flows appear to incorporate older (pre-industrial) material masking the isotopic signature of pollutant Pb. Large variability in the upper canyon reflects continuous sediment resuspension by bottom currents. Stronger average bottom currents are associated with higher 206Pb/ 207Pb ratios of sediment trap particulate material and hence decreased influence of pollutant Pb. This may reflect preferential resuspension of natural Pb at the canyon floor and/or additional remobilization of older, less-polluted sediment in adjacent areas such as the canyon walls.

Richter, T. O.; de Stigter, H. C.; Boer, W.; Jesus, C. C.; van Weering, T. C. E.

2009-02-01

310

New High-Resolution Mapping of Submarine Canyons in the Mid-Atlantic Continental Margin  

NASA Astrophysics Data System (ADS)

During June 2011, a BOEMRE/NOAA/USGS -funded multibeam bathymetry survey mapped the upper reaches (<900-m depths) of the Norfolk, Washington, and Baltimore canyons. Combined with existing multibeam bathymetry of the continental slope and rise, the new data provide a detailed view of the sedimentary processes that shaped the mid-Atlantic margin. The shelf-breaching canyon heads are surrounded by two terraces at depths of 95-100 m and 115-125 m in the Norfolk and Washington canyons and at depths of 115-125 m and 135-145 m in the Baltimore canyon. These terraces may represent paleo-shorelines formed during sea level stillstands. The canyon thalwegs within the shelf appear to be filled with sand in accord with old core results. The gradient of their thalweg profile is variable and relatively low across the shelf, slope, and upper rise, in contrast to the concave gradient of most non-shelf breaching canyons in the region. A few of the non-shelf breaching canyons in the mid-Atlantic margin also have relatively low and variable gradients suggesting that they once breached the shelf but are now completely filled. The seaward extensions of the Norfolk, Washington, and Baltimore canyons onto the continental rise are characterized by channels bordered by 100-200 m high levees. In places, these channels meander tightly. The extensions of other canyons onto the rise are either defined by subtle, linear depressions or cannot be traced. Channel-capture by adjacent canyons and channel abandonment originate in the lower slope and were prompted by either landslides or levee breaching. These observations indicate dynamic outer shelf deltas fed by large rivers, which were active at the last glacial maximum (LGM). The river channels on the shelf have been progressively filled during the Holocene. The clear expression of levied channels on the continental rise that extend from shelf-breaching canyons suggests that these canyons were the last ones to deliver turbidity flows to the rise. The terraces, assuming they are former shorelines, indicate that shelf-breaching canyon heads were incised into the shelf during or prior to the LGM. Some of the channels on the rise are partially filled by landslide deposits, suggesting that landslides have continued to shape the rise during the Holocene.

ten Brink, U. S.; Chaytor, J. D.; Brothers, D. S.; Twichell, D. C.; Ross, S. W.; Brooke, S.

2011-12-01

311

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

USGS Publications Warehouse

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.

Grams, Paul E.

2013-01-01

312

Travel Time Distribution Modeling in the Valles Caldera, New Mexico  

NASA Astrophysics Data System (ADS)

Modeling the transit times of catchment waters is of paramount importance in hydrology. The distribution of the time it takes for individual water molecules to move through a hydrologic system (a.k.a., the travel time distribution) is a fundamental characterization of a catchment. Travel time distributions are affected by a variety of physical characteristics of catchments (e.g., vegetation type, degree of soil development) that depend on the amount of solar energy the catchment receives. These characteristics, therefore, can be considered a function of aspect. The goal of this research is to constrain travel time distributions on a series of eight radial mountain streams having different slope aspects on Redondo Peak, a resurgent dome in the center of the Valles Caldera, near Los Alamos, New Mexico. Redondo Peak is an excellent natural laboratory for this type of experiment because all aspects are represented on different sides of the mountain while the internal geology and climate are relatively consistent. To model the transit time distributions of each catchment, variations of chemical load of the snowpack, isotopic compositions of meltwater samples, and snowcover distribution data from closely related studies are coupled with periodic stream and precipitation samples that are analyzed for stable water isotopes content. Additional information comes from a network of temperature sensors to monitor the distribution of snowmelt and headwater stream discharge as well as a series of flumes to capture the flows from the streams. The travel time distributions determined in this project provide a bottom up approach to verify catchment-scale models.

Broxton, P. D.; Troch, P. A.; Brooks, P. D.; Lyon, S. W.; Gustafson, J. R.; Veatch, W. C.

2007-12-01

313

Dense shelf water cascades in two northwestern Mediterranean submarine canyon heads during winters 2007 and 2008  

NASA Astrophysics Data System (ADS)

Submarine canyons incised in continental margins are considered to be preferential pathways for the exchange of water and particles between the coastal area and the open sea. Hydrodynamics and sediment transport processes in submarine canyons depend upon several forcing conditions in the region such as general circulation, seafloor morphology and atmospheric regime. The off-shelf sediment transport trough submarine canyons, due to storms and river floods, can be significant and recently dense shelf-water cascading (DSWC) has been also identified as an important transport mechanism able to generate high sediment fluxes in submarine canyons. DSWC is seasonal, resulting from the formation of dense water by cooling and/or evaporation over the shelf, and occurs on both high- and low latitude continental margins. The Palamós and the Cap de Creus submarine canyon heads were instrumented during two consecutive winters to study their respective role in the dynamics of the sediment transport on the northwestern Mediterranean Sea. The Cap de Creus submarine canyon has been intensively studied during the past years as it acts as a major transport conduit during storms and DSWC events. On the contrary, little information exists about the sediment transport processes operating within the Palamós submarine canyon during winter conditions. Observational work during this study consisted of a series of field measurements carried out with instrument moorings during winters 2007 and 2008 at the heads of both submarine canyons, at around 300 m depth. These moorings were equipped with a current meter with temperature, conductivity, pressure and turbidity sensors, placed at 5 m above the seafloor. Multibeam bathymetry from both canyon heads was also acquired and used to determine the canyon axis morphology, which was considered to compute down-canyon fluxes. Forcing conditions were obtained from oceanographic buoys and gaps in the wave height and peak period time series were filled with models outputs. Daily river discharges from nearby rivers were also analyzed. Sediment transport events during winters 2007 and 2008 were quite similar, and several DSWC events were identified and compared among them. Down-canyon current velocities of > 60 cm/s were detected in the Cap de Creus Canyon, and velocities of > 40 cm/s in the Palamós Canyon. Increases in current speed were associated with subtle drops in temperature (~ 1 °C) related to DSWC, and peaks of suspended sediment concentration. Values up to 170 mg/l were recorded during both studied winters at the Cap de Creus canyon head coinciding with the first DSWC event concurrent with an eastern storm. During both study periods no relation was found between sediment transport events and nearby river discharges. The amount of sediment transported during DSWC events at the Cap de Creus Canyon was one order of magnitude greater than the one observed at the Palamós Canyon. This corroborates the fact that most of the off-shelf sediment transport in the northwestern Mediterranean during DSWC events occurs at the southwestern end of the Gulf of Lions, through the Cap de Creus submarine canyon.

Ribo, Marta; Puig, Pere; Palanques, Albert; Lo Iacono, Claudio

2010-05-01

314

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

NASA Astrophysics Data System (ADS)

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).

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

2014-01-01

315

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

PubMed

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 (?=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 ?>90°. Pollutant concentration increases as aspect ratio decreases. This concentration decreases exponentially in the vertical direction, and decreases as ? 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. PMID:22760437

Yassin, Mohamed F; Ohba, Masaake

2012-09-01

316

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

NASA Astrophysics Data System (ADS)

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.

Lamb, Michael P.; Fonstad, Mark A.

2010-07-01

317

Modelling dispersion of traffic pollution in a deep street canyon: Application of CFD and operational models  

NASA Astrophysics Data System (ADS)

In this study, numerical modelling of the flow and concentration fields has been undertaken for a deep street canyon in Naples (Italy), having aspect ratio (i.e. ratio of the building height H to the street width W) H/ W = 5.7. Two different modelling techniques have been employed: computational fluid dynamics (CFD) and operational dispersion modelling. The CFD simulations have been carried out by using the RNG k- ? turbulence model included in the commercial suite FLUENT, while operational modelling has been conducted by means of the WinOSPM model. Concentration fields obtained from model simulations have been compared with experimental data of CO concentrations measured at two vertical locations within the canyon. The CFD results are in good agreement with the experimental data, while poor agreement is observed for the WinOSPM results. This is because WinOSPM was originally developed and tested for street canyons with aspect ratio H/ W ? 1. Large discrepancies in wind profiles simulated within the canyon are observed between CFD and OSPM models. Therefore, a modification of the wind profile within the canyon is introduced in WinOSPM for extending its applicability to deeper canyons, leading to an improved agreement between modelled and experimental data. Further development of the operational dispersion model is required in order to reproduce the distinct air circulation patterns within deep street canyons.

Murena, Fabio; Favale, Giuseppe; Vardoulakis, Sotiris; Solazzo, Efisio

318

Bryant Canyon fan system: An unconfined, large river-sourced system in the Northwestern Gulf of Mexico  

SciTech Connect

The high-relief sea floor of the northwestern Gulf of Mexico slope is pockmarked by salt-rimmed minibasins and dissected by channels and canyons. Analysis of multichannel seismic reflection data reveals that Bryant Canyon and its fan are an unconfined, fluvially sourced system associated with the ancestral Mississippi River. Bryant Canyon eroded an extensive bypassing cut on the slope and delivered sediments to the unconfined area of the base of slope where they formed a fan. The canyon incorporates several minibasins and shallow salt structures. The canyon cross sections are easily recognizable in the minibasins, but are partially or completely obliterated by salt tectonism where the canyon incised the shallow salt structures. Salt appears to have encroached upon the canyon after abandonment and restored the sea floor to its pre-canyon, low-relief profile. We interpreted three depositional units in the Pleistocene section of the Bryant Canyon Fan. The lower units are characterized by erosional surfaces or channels and mass-transport deposits. The top unit consists of low- to moderate-amplitude reflections with moderate continuity, suggesting relatively uniform deposition. The widespread occurrence of erosional surfaces and channels in the lower units may suggest extensive canyon activity during sea level falls. Decreased depositional energy from lower units upward indicates abandonment of the canyon or eastward shift of the ancestral Mississippi River. The Bryant Canyon Fan system contains several potential reservoir facies, including turbidites, trapped in high-relief minibasins during periods of less extensive canyon activity, that may exhibit good reservoir quality and massive sand occurring in canyon fill. Channel deposits and distal, unchannelized turbidites of the fan also may contain reservoir-quality sand. Mass-transport deposits with moderate- to high-amplitude reflections and levee deposits close to channels probably contain sand.

Lee, G.H. [Kunsan National Univ. (Korea, Democratic People`s Republic of); Watkins, J.S.; Bryant, W.R. [Texas A& M Univ., College Station, TX (United States)

1996-03-01

319

Fish Passage Assessment: Big Canyon Creek Watershed, Technical Report 2004.  

SciTech Connect

This report presents the results of the fish passage assessment as outlined as part of the Protect and Restore the Big Canyon Creek Watershed project as detailed in the CY2003 Statement of Work (SOW). As part of the Northwest Power Planning Council's Columbia Basin Fish and Wildlife Program (FWP), this project is one of Bonneville Power Administration's (BPA) many efforts at off-site mitigation for damage to salmon and steelhead runs, their migration, and wildlife habitat caused by the construction and operation of federal hydroelectric dams on the Columbia River and its tributaries. The proposed restoration activities within the Big Canyon Creek watershed follow the watershed restoration approach mandated by the Fisheries and Watershed Program. Nez Perce Tribal Fisheries/Watershed Program vision focuses on protecting, restoring, and enhancing watersheds and treaty resources within the ceded territory of the Nez Perce Tribe under the Treaty of 1855 with the United States Federal Government. The program uses a holistic approach, which encompasses entire watersheds, ridge top to ridge top, emphasizing all cultural aspects. We strive toward maximizing historic ecosystem productive health, for the restoration of anadromous and resident fish populations. The Nez Perce Tribal Fisheries/Watershed Program (NPTFWP) sponsors the Protect and Restore the Big Canyon Creek Watershed project. The NPTFWP has the authority to allocate funds under the provisions set forth in their contract with BPA. In the state of Idaho vast numbers of relatively small obstructions, such as road culverts, block thousands of miles of habitat suitable for a variety of fish species. To date, most agencies and land managers have not had sufficient, quantifiable data to adequately address these barrier sites. The ultimate objective of this comprehensive inventory and assessment was to identify all barrier crossings within the watershed. The barriers were then prioritized according to the amount of habitat blocked at each site and the fish life history stages impacted. This assessment protocol will hopefully prove useful to other agencies and become a model for use in other watersheds.

Christian, Richard

2004-02-01

320

Photomosaics and logs of trenches on the San Andreas Fault at Mill Canyon near Watsonville, California  

USGS Publications Warehouse

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.

Fumal, Thomas E.; Dawson, Timothy E.; Flowers, Rebecca; Hamilton, John C.; Heingartner, Gordon F.; Kessler, James; Samrad, Laura

2004-01-01

321

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

USGS Publications Warehouse

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.

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

1984-01-01

322

Axial Channel Morphology Fill and Movement Within Submarine Canyons off California  

NASA Astrophysics Data System (ADS)

Axial channels of seven submarine canyons off California have recently been investigated with ultrahigh resolution multibeam surveys. Vibracores collected from remotely operated vehicles (ROVs) provide ground truth data on the materials within the axis of six of these canyons. Acoustic beacons were used to track movement of the seafloor within the axis of Monterey Canyon. Multibeam bathymetry (0.15 m vertical precision and 1.0 m horizontal resolution at 50 m survey altitude) and chirp seismic-reflection profiles (0.11 m vertical resolution) were collected from an autonomous underwater vehicle (AUV). Inertial navigation combined with Doppler velocity sonar allows the AUV to navigate the sinuous canyons at 3 kt on a pre-programmed route ~50 m above the seafloor. Submarine canyons that head near the shoreline (Monterey, Hueneme, Mugu, Redondo and La Jolla) contain similar wave-like bedforms with 20-100 m wavelengths and amplitudes up to 2.5 m oriented roughly perpendicular to the channel axis. These bedforms are asymmetric in profile with a steep down-canyon face and crescent-shaped, concave down-canyon. They are observed throughout the surveys (80-800 m water depth) and appear to form genetically similar packages (0.1 to 3 km long) that terminate upslope at a somewhat higher topographic step. Generally, bedform groups are found within the axial channel, but occasionally extend up the canyon walls. ROV-collected vibracores show that the wave-like bedforms comprise recent, coarse-grained gravity flow deposits, suggesting these canyons are active. In contrast, two submarine canyons with heads on the outer shelf (Soquel and Santa Monica) lack these wave-like bedforms and have relatively smooth axial channel floors. Vibracores show these canyons are filled with generally uniform fine-grained sediments, suggesting they are inactive. Apparently wave-like bedforms are common features of active submarine canyons. To assess whether sediment within a canyon floor is moved by traction currents or mass transport, three acoustic beacons were deployed in Monterey Canyon (~290 m water depth) in February 2007. The beacons were placed in 50-cm-high ~45 kg concrete monuments. These boulder-sized monuments were buried leaving only the top of the beacon extending ~6 cm above the seafloor. The position of these beacons was re-surveyed 8 times between February 2007 and July 2008. While the beacons did not move between most surveys, two down-canyon shifts of ~150 m and >1,200 m were measured. The episodic movement of the buried monuments suggests that the seafloor was remobilized to more than 50-cm- depth during sediment transport events. Four repeat AUV multibeam surveys were also conducted during the first half of 2007. These surveys show that the wave-shaped bedforms occur in the canyon axis down to at least 1,100 m water depth. Because the buried monuments have moved more than two wavelengths down- canyon during an individual event, identification and tracking of individual bedforms between events has proven to be difficult. Apparently, these wave-shaped bedforms are produced during brief, discrete mass transport events.

Paull, C. K.; Caress, D. W.; Ussler, W.; Lundsten, E.; Thomas, H.

2008-12-01

323

Critical Climate Controls and Information Needs for the Glen Canyon Adaptive Management Program and Environmental Assessment in the Grand Canyon Region  

NASA Astrophysics Data System (ADS)

Climatic drivers of episodic to interdecadal variations to the observed changes in the flood magnitude, timing and spatial scales affect the sediment inputs to the Colorado River ecosystem. Since the 1963 closure of Glen Canyon Dam, the dominant sole major supplier of sand to the Colorado River in the upper portion of Grand Canyon is the Paria River, which supplies about 6% of the pre-dam supply of sand at the upstream boundary of Grand Canyon National Park. Sand is delivered by the Paria River during short-duration (< 24 hours), large magnitude (up to 300 cubic meters/second) floods that occur primarily during the warm season (July-October). The planning and decision processes in the Glen Canyon Dam Adaptive Management Program (GCD-AMP) strive to balance numerous, often competing, objectives, such as,water supply, hydropower generation, low flow maintenance, maximizing conservation of the tributary supplied sediment, endangered species recovery, and cultural resources. In this work, we focus on a key concern identified by the AMP, related to the timing and volume of sediment input into Grand Canyon. Adequate sediment inputs into the river ecosystem Canyon combined with active flow management, of the timed in the form of strategically timed bypass releases from Glen Canyon Dam, support the restoration and maintenance of sand bar habitats and instream ecology. Variability in regional precipitation distribution on multiple time scales is diagnosed with emphasis on understanding the relative role of East Pacific tropical storms, North Pacific sea surface temperatures, and subtropical moisture sources. On longer time scales, structured variations in the sediment supply imply a changing baseline for mean ecological and geomorphological conditions in the Canyon, counter to the static view taken in the current environmental impact assessments. Better understanding of the coupled climate-hydrologic variations on multiple time scales is increasingly recognized as critical input for adaptive management (both passive and active). In collaboration with the GCD-AMP, this work deliberately identifies the entry-points for predictive hydroclimatic information at appropriate lead times. From the standpoint of this active adaptive management program, lead climate information allows scientists and managers to anticipate geomorphic response from critical tributaries, that in turn trigger large-scale, experimental releases from Glen Canyon Dam. Similar future studies are planned for the Little Colorado River, as flood frequency in that larger drainage is tied to both the ecosystem's sand supply and the spawning success and recruitment of endangered humpback chub.

Melis, T. S.; Jain, S.; Topping, D. J.; Pulwarty, R. S.; Eischeid, J. K.

2005-12-01

324

Recreation and jobs in the Glen Canyon Dam region  

SciTech Connect

Natural resource economists have estimated the nonmarket benefits provided by streamflows in several recent research papers. The current paper also examines the economic implications of water based recreational activities. The analysis uses a software package and database called IMPLAN to estimate the jobs impacts of expenditures for recreation trips to the Lee`s Ferry reach on the Colorado River. The discussion describes the basic input-output model and water based recreation activities at the Lee`s Ferry reach. Non-resident river recreation trip expenditures to the Glen Canyon Dam region generate 585 jobs. The estimates presented here add further credence and policy weight to the premise that the outdoor recreation sector of the economy is relatively labor intensive.

Douglas, A.J.; Harpman, D.A. [National Biological Survey, Ft. Collins, CO (United States); [Denver Federal Center, CO (United States)

1995-12-31

325

Is there excess argon in the Fish Canyon magmatic system?  

NASA Astrophysics Data System (ADS)

Some phenocrysts from the Fish Canyon Tuff (San Juan volcanic field, south-western Colorado, USA) have yielded anomalously old 40Ar/39Ar apparent ages and yet the sanidine ages are sufficiently reproducible to allow its use as an international standard. The eruption age of the Fish Canyon tuff has recently been determined by high precision analysis and recalibration of the decay constants based on the sanidine standard at 28.305 ± 0.036 Ma [1], slightly younger than the generally accepted U-Pb age. Previously, minerals from the tuff have been used in various geochronological studies e.g., fission-track; U-Pb; Rb-Sr; K-Ar and 40Ar/39Ar, but U-Pb zircon ages which range 28.37 - 28.61 Ma appear to be older than the sanidine and other minerals, including biotite, yield older ages (27.41 - 28.25 Ma for biotite) [2]. In the Fish Canyon volcanic system, the erupted products are thought to exist in the magma chamber for significant periods prior to eruption [3] and then pass rapidly from a high temperature magmatic environment (where Ar is free to re-equilibrate among the minerals), to effectively being quenched upon eruption (where Ar becomes immobile). Artificially elevated ages, older than eruption age, have been identified in some 40Ar/39Ar geochronological studies (e.g. [4]). These older ages may either reflect; 1) argon accumulation in pheno- or xenocrysts (by radioactive decay of parent 40K), 2) excess argon (40ArE) incorporated into a mineral during crystallisation (via diffusion into the mineral lattice or hosted within fluid or melt inclusions) or 3) inherited radiogenic argon (the dated material contains a component older than the age of eruption) [5]. To better understand the effects of 40ArE on 40Ar/39Ar apparent ages we have conducted a detailed study of intra-grain grain age variations by UV-LAMP Ar-analysis. Analysis of polished thick sections has been performed in-situ using a 213nm laser and Nu Instruments Noblesse which is able to discriminate against interfering peaks at mass 36 allowing us to correct for the atmospheric 40Ar content. By using this method to analyse potassium-rich minerals (sanidine and biotite) and potassium-poor minerals (quartz and plagioclase), it has been possible to study the distribution of argon within these mineral phases and its incorporation into melt, fluid and solid inclusions. Here we report new 40Ar/39Ar intra-grain age data of minerals from the Fish Canyon Tuff, which despite being well characterised and extensively researched has not yet been a subject for this particular technique. [1] Renne P. R. et al., (2010) Geochim. Cosmochim. Acta, 74, 5349-5367. [2] Bachmann, O. et al., (2007) Chemical Geology, 236, 134-166.[3] Charlier, B.L.A. et al., (2007) Journal of Petrology, 48, 1875-1894. [4] Esser, R. P. et al., (1997) Geochim. Cosmochim. Acta, 61, 3789-3801. [5] Kelley, S. (2002) Chemical Geology, 188, 1-22. Corresponding Author: c.m.wilkinson@open.ac.uk

Wilkinson, C. M.; Sherlock, S.; Kelley, S. P.; Charlier, B. L.

2010-12-01

326

National uranium resource evaluation, Marble Canyon Quadrangle, Arizona and Utah  

SciTech Connect

The Marble Canyon Quadrangle (2/sup 0/), northeast Arizona, was evaluated to a depth of 1500 m for uranium favorability using National Uranium Resource Evaluation criteria. Known mines and prospects were examined; field reconnaissance was done in selected areas of the quadrangle; and a ground-water geochemical survey was made in the southeast third of the quadrangle. The Shinarump and Petrified Forest Members of the Triassic Chinle Formation, which is exposed in the western and northeastern parts of the quadrangle and is present beneath the surface of much of the quadrangle, were found favorable for channel-sandstone uranium deposits. A portion of the Cretaceous Toreva Formation in the southeast part of the quadrangle was found favorable for peneconcordant-sandstone uranium deposits. The western part of the quadrangle was found favorable for uranium concentrations in breccia pipes.

Field, M T; Blauvelt, R P

1982-05-01

327

RECALIBRATION OF H CANYON ONLINE SPECTROPHOTOMETER AT EXTENDED URANIUM CONCENTRATION  

SciTech Connect

The H Canyon online spectrophotometers are calibrated for measurement of the uranium and nitric acid concentrations of several tanks in the 2nd Uranium Cycle.[1] The spectrometers, flow cells, and prediction models are currently optimized for a process in which uranium concentrations are expected to range from 0-15 g/L and nitric acid concentrations from 0.05-6 M. However, an upcoming processing campaign will involve 'Super Kukla' material, which has a lower than usual enrichment of fissionable uranium. Total uranium concentrations will be higher, spanning approximately 0-30 g/L U, with no change in the nitric acid concentrations. The new processing conditions require the installation of new flow cells with shorter path lengths. As the process solutions have a higher uranium concentration, the shorter path length is required to decrease the absorptivity to values closer to the optimal range for the instrument. Also, new uranium and nitric acid prediction models are required to span the extended uranium concentration range. The models will be developed for the 17.5 and 15.4 tanks, for which nitric acid concentrations will not exceed 1 M. The restricted acid range compared to the original models is anticipated to reduce the measurement uncertainty for both uranium and nitric acid. The online spectrophotometers in H Canyon Second Uranium Cycle were modified to allow measurement of uranium and nitric acid for the Super Kukla processing campaign. The expected uranium concentrations, which are higher than those that have been recently processed, required new flow cells with one-third the optical path length of the existing cells. Also, new uranium and nitric acid calibrations were made. The estimated reading uncertainties (2{sigma}) for Tanks 15.4 and 17.5 are {approx}5% for uranium and {approx}25% for nitric acid.

Lascola, R

2008-10-29

328

Web-based Interactive Landform Simulation Model - Grand Canyon  

NASA Astrophysics Data System (ADS)

Earth science educators need interactive tools to engage and enable students to better understand how Earth systems work over geologic time scales. The evolution of landforms is ripe for interactive, inquiry-based learning exercises because landforms exist all around us. The Web-based Interactive Landform Simulation Model - Grand Canyon (WILSIM-GC, http://serc.carleton.edu/landform/) is a continuation and upgrade of the simple cellular automata (CA) rule-based model (WILSIM-CA, http://www.niu.edu/landform/) that can be accessed from anywhere with an Internet connection. Major improvements in WILSIM-GC include adopting a physically based model and the latest Java technology. The physically based model is incorporated to illustrate the fluvial processes involved in land-sculpting pertaining to the development and evolution of one of the most famous landforms on Earth: the Grand Canyon. It is hoped that this focus on a famous and specific landscape will attract greater student interest and provide opportunities for students to learn not only how different processes interact to form the landform we observe today, but also how models and data are used together to enhance our understanding of the processes involved. The latest development in Java technology (such as Java OpenGL for access to ubiquitous fast graphics hardware, Trusted Applet for file input and output, and multithreaded ability to take advantage of modern multi-core CPUs) are incorporated into building WILSIM-GC and active, standards-aligned curricula materials guided by educational psychology theory on science learning will be developed to accompany the model. This project is funded NSF-TUES program.

Luo, W.; Pelletier, J. D.; Duffin, K.; Ormand, C. J.; Hung, W.; Iverson, E. A.; Shernoff, D.; Zhai, X.; Chowdary, A.

2013-12-01

329

Hydrology in the Durius Valles Region: Evaluation of Possible Correlation with Volcanism and Magnetic Anomalies  

NASA Technical Reports Server (NTRS)

We envision the contribution of subglacial flows, hydrothermalism and sapping in the Durius Valles system and the consequences in term of climate on Mars in recent geological times. We evaluate the possible correlation of the hydrology with volcanism and magnetic anomalies.

Cabrol, Natalie A.; Marinangeli, Lucia; Grin, Edmond A.

2000-01-01

330

Tectonic pressurization of aquifers in the formation of Mangala and Athabasca Valles, Mars  

Microsoft Academic Search

Mangala and Athabasca Valles are the type examples of a distinct class of outflow channels that debouch directly from extensional tectonic features. We here demonstrate that the tectonic events responsible for the formation of the graben and fissures at the sources of the channels would have likely resulted in a near-instantaneous pressurization of the surrounding aquifers. Subsequent drainage of the

Jeffrey C. Hanna; Roger J. Phillips

2006-01-01

331

KERNEL IMAGE SIMILARITY CRITERION Vicent Talens, Jose Moreno and Gustavo Camps-Valls  

E-print Network

objective measures to evaluate image quality [1]. The standard root-mean-square- error (RMSE properties. We illustrate the performance in evaluating the quality of nat- ural photographic imagesKERNEL IMAGE SIMILARITY CRITERION Vicent Talens, Jos´e Moreno and Gustavo Camps-Valls 1 Image

Camps-Valls, Gustavo

332

DECISIONES DE FINANCIACIÓN DE LA INDUSTRIA METALMECÁNICA DEL VALLE DEL CAUCA  

Microsoft Academic Search

Esta investigación tiene como objetivo conocer los factores que influyen en la toma de decisiones de financiamiento a largo plazo en la industria metalmecánica del Valle del Cauca (Colombia), hasta ahora no explorados. Se realiza un estudio para el periodo 2000-2006, utilizando como método, el análisis de la estructura financiera y la aplicación de un modelo econométrico de Datos de

JORGE ALBERTO RIVERA GODOY

2008-01-01

333

Screening of antibacterial activity of Amaicha del Valle (Tucumán, Argentina) propolis  

Microsoft Academic Search

Propolis is extensively used in Argentine folk medicine. Alcoholic extracts of propolis from four localities of Amaicha del Valle (El Paraiso, La Banda Este, La Banda Oeste and El Molino), Province of Tucumán and from Cerrillos, Province of Santiago del Estero, Argentina were prepared. All showed antibacterial activity against Gram positive bacteria, the propolis from La Banda Este being the

M. I. Nieva Moreno; M. I. Isla; N. G. Cudmani; M. A. Vattuone; A. R. Sampietro

1999-01-01

334

Complete remission with urssodeoxycholic acid ... Duclos-Valle et al. COMPLETE REMISSION WITH URSODEOXYCHOLIC ACID  

E-print Network

WITH URSODEOXYCHOLIC ACID OF TYPE 1 AUTOIMMUNE HEPATITIS RESISTANT TO AZATHIOPRINE AND STEROIDS Jean-Charles Duclos remission with urssodeoxycholic acid ... Duclos-Vallée et al. -2- Autoimmune hepatitis, intolerance Combination therapy with steroids and azathioprine is the reference treatment for autoimmune hepatitis

335

Observations and modeling of mixing processes in a fresh water reservoir - Valle de Bravo (Mexico)  

E-print Network

. For this purpose, observations were made in Valle de Bravo's freshwater reservoir, about 100 km west of Mexico City and at an elevation of 1830 m above sea surface. Turbulence kinetic energy dissipation (TKED) rates were estimated by fitting a theoretical Batchelor...

Singhal, Gaurav

2007-04-25

336

Deciduous Fruit Options for North FL Landscapes by Terry DelValle, Urban Horticulture Extension Agent  

E-print Network

Deciduous Fruit Options for North FL Landscapes by Terry DelValle, Urban Horticulture Extension your homework first. Site Selection: Here is a list of criteria. Fruit require an open sunny spot. Soil pH should be slightly acid, around 6.0 to 6.5, with the exception of blueberries which grow best

Hill, Jeffrey E.

337

A tectonically controlled basin-fill within the Valle del Cauca, West-Central Colombia  

SciTech Connect

Tertiary strata of the Valle del Cauca reflect a forearc/foreland basin tectonic history spanning a period from pre-uplift of the Cordillera Central to initiation of uplift of the Cordillera Occidental. Stratigraphy of the Valle del Cauca begins with Jurassic-Cretaceous rocks of exotic and/or volcanic provenance and of oceanic origin. Unconformably overlying these are Eocene to Oligocene basal quartz-rich sandstones, shallow marine algal limestones, and fine-grained fluvial/deltaic mudstones and sandstones with coalbeds. These Eocene to Oligocene deposits represent a period of low tectonic activity. During late Oligocene to early Miocene, increased tectonic activity produced conglomeratic sediments which were transported from east to west, apparently derived from uplift of the Cordillera Central, and deposited within a fluvial to deltaic setting. East-west shortening of the Valle del Cauca basin folded the Eocene to early Miocene units, and additional uplift of the Cordillera Central during the later Miocene resulted in syn-tectonic deposition of alluvial fans. After additional fold and thrust deformation of the total Eocene-Miocene basin-fill, tectonic activity abated and Pliocene-Quaternary alluvial and lacustrine strata were deposited. Within the framework of this depositional and tectonic history of the Valle del Cauca, hydrocarbon exploration strategies can be formulated and evaluated.

Rine, J.M.; Keith, J.F. Jr.; Alfonso, C.A.; Ballesteros, I.; Laverde, F.; Sacks, P.E.; Secor, D.T. Jr. (Univ. of South Carolina, Columbia (United States)); Perez, V.E.; Bernal, I.; Cordoba, F.; Numpaque, L.E. (Ecopetrol, Bogota (Colombia))

1993-02-01

338

Clustered streamlined forms in Athabasca Valles, Mars: Evidence for sediment deposition during floodwater ponding  

E-print Network

Clustered streamlined forms in Athabasca Valles, Mars: Evidence for sediment deposition during history of this young Martian outflow channel. D 2005 Elsevier B.V. All rights reserved. Keywords: Mars system on Mars (Tanaka, 1986). The most recent activity has been dated by crater counting at less than

Perfect, Ed

339

Path Selection and Coordination for Multiple Robots via Nash Equilibria Steven M. LaValle  

E-print Network

Path Selection and Coordination for Multiple Robots via Nash Equilibria Steven M. LaValle lavalle, Urbana, IL 61801 Abstract Wepresent a methodfor analyzing and selecting time- optimal coordination the problem of coordinating multiple robots. Most traditional approaches to coordi- nation either form

Hutchinson, Seth

340

Ox Mountain sanitary landfill: Apanolio Canyon expansion site, San Mateo County, California. Volume 2. Appendix. Final report  

SciTech Connect

Further studies include: plants Observed in Apanolio Canyon; Animals Expected or Observed in Apanolio Canyon; Marbled Murrelet Survey; Review of Available Scientific Information on Six Candidate Insects; Update on Status of Candidate Insects; Apanolio Canyon Sensitive Plant Investigation; Fisheries Resources of Upper Apanolio, Benthic Invertebrate Survey of Apanolio, Corinda Los Trancos, and Pilarcitos Creeks, San Mateo County, California; Streamflows and Velocity of Flows at the Bongard diversion Dam in Apanolio Canyon; A Spring Survey to Determine the Presence or Absence of the San Francisco Garter Snake (Thamnophis sirtalis tetrataenis) in Two Tributaries of Pilarcitos Creek, Half Moon Bay, CA; Wildlife and Fisheries Mitigation Plan, Ox Mountain Sanitary Landfill, Apanolio Canyon Expansion Site; Correspondence Site Selection Criteria Information; Draft Contingency Remedial Action Plan; Leachate Collection and Removal System (LCRS) and Leachate/Contaminated Groundwater Treatment Systems; Apanolio Creek Streamflow Augmentation Plan; Apanolio Canyon Lower Aquifer Recharge Plan; Application for Exemptions - Technical Informations; Geotechnical Study and Specifications, Subgrade Barrier and Clay Liner System; Apanolio Canyon Boring Logs; Potentiometric Surface Maps, Apanolio Canyon; Geologic Cross Sections - Apanolio Canyon; Interim Report on Leachate Exposure Test Program, Apanolio Canyon Landfill Expansion.

Not Available

1989-04-01

341

78 FR 42902 - Safety Zone; Olympus Tension Leg Platform, Mississippi Canyon Block 807, Outer Continental Shelf...  

Federal Register 2010, 2011, 2012, 2013

...Mississippi Canyon Block 807, Outer Continental Shelf on the Gulf of Mexico AGENCY...Proposed Rulemaking OCS Outer Continental Shelf A. Public Participation and...Subjects in 33 CFR Part 147 Continental shelf, Marine safety,...

2013-07-18

342

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

E-print Network

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 ...

Li, Xian-Xiang

343

78 FR 3370 - Proposed Establishment of the Ballard Canyon Viticultural Area  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF THE TREASURY Alcohol and Tobacco Tax and Trade Bureau 27 CFR...Ballard Canyon Viticultural Area AGENCY: Alcohol and Tobacco Tax and Trade Bureau, Treasury...SUMMARY: The Alcohol and Tobacco Tax and Trade Bureau...

2013-01-16

344

78 FR 42799 - Glen Canyon Dam Adaptive Management Work Group Meetings  

Federal Register 2010, 2011, 2012, 2013

...the AMWG, a technical work group (TWG), a Grand Canyon Monitoring...Bureau of Reclamation, Upper Colorado Regional Office, 125 South State...Chief, Adaptive Management Work Group, Upper Colorado Regional Office, Salt Lake...

2013-07-17

345

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

346

Origin of Theater-headed Tributaries to Escalante and Glen Canyons, Utah  

NASA Astrophysics Data System (ADS)

Theater-headed tributaries to Glen Canyon, Utah, are important analogs to martian valley networks. Our field study suggests a hybrid model involving seepage weathering of Navajo sandstone, sheet fracturing, and transport of debris by flash floods.

Irwin, R. P.; Fortezzo, C. M.; Tooth, S. E.; Howard, A. D.; Zimbelman, J. R.; Barnhart, C. J.; Benthem, A. J.; Brown, C. C.; Parsons, R. A.

2009-03-01

347

65 FR 12990 - Boulder Canyon Project-Firm Power Services Base Charge and Rates  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project-Firm Power Services Base Charge and Rates AGENCY: Western Area Power Administration, DOE. ACTION: Notice of proposal to extend...

2000-03-10

348

Ice Climbing in Clear Creek Canyon A climbing trip report by Glenn Murray  

E-print Network

with Sean in Clear Creek Canyon, Sunday, Jan.23, 1995. We encounter difficulties and women. I originally people have whacked holes into it so that I could hook all the way up, but I feel insecure, put

349

Internal structure of the Kern Canyon Fault, California: a deeply exhumed strike-slip fault  

E-print Network

Deformation and mineral alteration adjacent to a 2 km long segment of the Kern Canyon fault near Lake Isabella, California are studied to characterize the internal structure of the fault zone and to understand the development of fault structure...

Neal, Leslie Ann

2012-06-07

350

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

Federal Register 2010, 2011, 2012, 2013

...Statement for the Backcountry Management Plan for Grand Canyon National...of the park's backcountry, levels of commercial services, levels of administrative and scientific research activities, management of natural and cultural...

2011-04-27

351

2006Volume78number3 131 chenbach Canyon is an easily  

E-print Network

, 2005, we ended our hike in the relatively flat area of Upper Achenbach Canyon at roughly 1700 meters (Cane Cholla), Fouquieria splendens (Ocotillo), Dasylirion wheeleri (Sotol), Yucca baccata (Banana Yucca

Gorelick, Root

352

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

PubMed

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. PMID:18497296

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

2008-05-23

353

Lightning protection for the process canyons at the Savannah River site  

SciTech Connect

Westinghouse Savannah River Company (WSRC) has performed Lightning Studies for the existing Process Canyons at the Savannah River Site (SRS). These studies were initiated to verify the lightning protection systems for the facilities and to compare the installations to the National Fire Protection (NFPA) Standard 780, Lighting Protection Code, 1992. The original study of the F-Canyon was initiated to develop answers to concerns raised by the Defense Nuclear Facility Safety Board (DNFSB). Once this study was completed it was determined that a similar study for H-Canyon would be prudent; followed by an evaluation of the Defense Waste Processing Facility (DWPF) Vitrification Building (S-Canyon). This paper will provide an overview of the nature of lightning and the principals of lightning protection. This will provide the reader with a basic understanding of the phenomena of lighting and its potential for damaging structures, components, and injuring personnel in or near the structure.

McAfee, D.E.

1995-12-31

354

A tertiary fold and thrust belt in the Valle del Cauca Basin, Colombian Andes  

NASA Astrophysics Data System (ADS)

Surface geology and heophysical data, supplemented by regional structural interpretations, indicate that the Valle del Cauca basin and adjacent areas in west-central Colombia form a west-vergent, basement-involved fold and thrust belt. This belt is part of a Cenozoic orogen developed along the west side of the Romeral fault system. Structural analysis and geometrical constraints show that the Mesozoic ophiolitic basement and its Cenozoic sedimentary cover are involved in a "thick-skinned" west-vergent foreland style deformation. The rocks are transported and shortened by deeply rooted thrust faults and stacked in imbricate fashion. The faults have a NE?SW regional trend, are listric in shape, developed as splay faults which are interpreted as joining a common detachment at over 10 km depth. The faults carry Paleogene sedimentary strata and Cretaceous basement rocks westward over Miocene strata of the Valle del Cauca Basin. Fold axes trend parallel or sub parallel to the thrust faults. The folds are westwardly asymmetrical with parallel to kink geometry, and are interpreted to be fault-propagation folds stacked in an imbricate thrust system. Stratigraphic evidence suggests that the Valle del Cauca basin was deformed between Oligocene and upper Miocene time. The kinematic history outlined above is consistent with an oblique convergence between the Panama and South American plates during the Cenozoic. A negative residual Bouguer anomaly of 20-70 mgls in the central part of the Valle del Cauca basin indicates that a substantial volume of low density sedimentary rocks is concealed beneath the thrust sheets exposed at the land surface. The hydrocarbon potential of the Valle del Cauca should be reevaluated in light of the structural interpretations presented in this paper.

Alfonso, C. A.; Sacks, P. E.; Secor, D. T.; Rine, J.; Perez, V.

1994-10-01

355

Geometry and styles of displacement transfer, eastern Sun River Canyon Area, Sawtooth Range, Montana  

E-print Network

GEOMETRY AND STYLES OF DISPLACEMENT TRANSFER, EASTERN SUN RIVER CANYON AREA, SAWTOOTH RANGE, MONTANA A Thesis by BARBARA LOUISE GOLDBURG Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1984 Major Subject: Geology GEOMETRY AND STYLES OF DISPLACEMENT TRANSFER, EASTERN SUN RIVER CANYON AREA, SAIAITOOTH RANGE, MONTANA A Thesis by BARBARA LOUISE GOLDBURG Approved as to style and content by: Jo...

Goldburg, Barbara Louise

2012-06-07

356

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

USGS Publications Warehouse

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.

Topping, D.J.; Rubin, D.M.; Vierra, L.E., Jr.

2000-01-01

357

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

Microsoft Academic Search

Our study employed large-eddy simulation (LES) based on a one-equation subgrid-scale model to investigate the flow field and\\u000a pollutant dispersion characteristics inside urban street canyons. Unstable thermal stratification was produced by heating\\u000a the ground of the street canyon. Using the Boussinesq approximation, thermal buoyancy forces were taken into account in both\\u000a the Navier–Stokes equations and the transport equation for subgrid-scale

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

2010-01-01

358

Colorado Canyons National Conservation Area 2003 visitor use survey : completion report  

USGS Publications Warehouse

This report represents the analysis of research conducted by the U.S. Geological Survey (USGS) for the Bureau of Land Management (BLM). The purpose is to provide socio-economic and recreational use information that can be used in the development of a Resource Management Plan (RMP) for the Colorado Canyons National Conservation Area (CCNCA). The results reported here deal primarily with recreation-based activities in four areas: Kokopelli Loops, Rabbit Valley, Loma Boat Launch, and Devil's Canyon.

Ponds, Phaedra D.; Gillette, Shana C.; Koontz, Lynne

2004-01-01

359

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

NASA Astrophysics Data System (ADS)

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.

Hazel, Joseph E.; Topping, David J.; Schmidt, John C.; Kaplinski, Matt

2006-03-01

360

Place-Naming, Environment, and Perception among the Canyon de Chelly Navajo of Arizona  

Microsoft Academic Search

Place-names may provide insights into cultures' linguistics, histories, habitats, and spatial and environmental perceptions. To yield such insights, I analyze a comprehensive inventory of 245 Navajo place-names of the Canyon de Chelly system, Arizona. The analysis first identifies positional and directional linguistic elements in place-names. Frequencies of references to natural features such as canyons, prominent rocks, water features, and so

Stephen C. Jett

1997-01-01

361

Scavenging rates and particle characteristics in and near the Lacaze-Duthiers submarine canyon, northwest Mediterranean  

Microsoft Academic Search

To better understand the particle exchange processes across the Pyrenean continental margin, sampling was conducted in 1994 and 1995 at stations in and near the Lacaze-Duthiers canyon in the northwestern Mediterranean. Moored current meters provide evidence of water transport along the canyon axis (cross-slope) and along-slope with the prevailing regional circulation. Turbidity measurements show surficial nepheloid layers (SNL) roughly coincident

M. Frignani; T Courp; J. K Cochran; D Hirschberg; L Vitoria i Codina

2002-01-01

362

Quantifying tidal signatures of the benthic nepheloid layer in Gaoping Submarine Canyon in Southern Taiwan  

Microsoft Academic Search

The benthic nepheloid layer (BNL) has been observed in the head region of the Gaoping\\/Kaoping Submarine Canyon (KPSC) throughout a year. The top of the BNL could be as high as 100m above the canyon floor in which the suspended sediment concentration (SSC) could be as high as 30mg\\/l. In the BNL, sand-sized particles comprise the largest size-class in the

James T. Liu; Yu Huai Wang; I-Huan Lee; Ray T. Hsu

2010-01-01

363

Twenty-nine months of geomorphic change in upper Monterey Canyon (2002–2005)  

Microsoft Academic Search

Time serial multibeam bathymetry is used to evaluate geomorphic trends and submarine processes in the upper 4 km of Monterey Canyon, California. Seven high-resolution bathymetric surveys conducted between September 2002 to February 2005 show that the upper canyon axis and head grew in volume 1000000 m3±700000 m3, at an average annual rate of 400000 m3\\/a±300000 m3\\/a through lateral erosion and vertical incision. This net loss

Douglas P. Smith; Rikk Kvitek; Pat J. Iampietro; Kendra Wong

2007-01-01

364

Temperature-gradient and heat-flow data, Panther Canyon, Nevada  

SciTech Connect

A series of six shallow temperature-gradient holes were drilled for Sunoco Energy Development Company in Panther Canyon, Pershing County, Nevada during the period March 24 through June 15, 1981. A proposed intermediate-depth gradient hole was spud but abandoned after encountering unresolvable drilling problems. The locations of these holes are shown on figure 1. This report summarizes the results of the Panther Canyon project.

Fisher, Marci A.; Gardner, Murray C.

1981-07-01

365

Explaining the relationship between prehistoric agriculture and environment at Chaco Canyon, New Mexico  

E-print Network

for the degree of MASTER OF ARTS December 1993 Major Subject: Anthropology EXPLAINING THE RELATIONSHIP BETWEEN PREHISTORIC AGRICULTURE AND ENVIRONMENT AT CHACO CANYON, NEW MEXICO A Thesis by G- YOUNG GANG Submitted to Texas A&M University in partial... Major Subject: Anthropology ABSTRACT Explaining the Relationship between Prehistoric Agriculture and Environment at Chaco Canyon, New Mexico. (December 1993) G-Young Gang, B. A. , Yeungnam University, Korea Chair of Advisory Committee: Dr. D. Bruce...

Gang, G-Young

2012-06-07

366

Discordant 14C-stratigraphies in upper Monterey Canyon: A signal of anthropogenic disturbance  

Microsoft Academic Search

Laminated fine-grained sediments drape the flanks and terraces on the sides of upper Monterey Canyon, where rapid sedimentation occurs in the relatively calm environment sandwiched between the wave-washed continental shelf and the sediment gravity-flow-scoured axial channel on the canyon floor. The isotopic composition of organic matter contained in these accumulating sediments shows that they are primarily of terrestrial origin and

Charles K. Paull; William Ussler; Patrick J. Mitts; David W. Caress; G. James West

2006-01-01

367

Depositional history and performance of a Bell Canyon sandstone reservoir, Ford-Geraldine field, west Texas  

Microsoft Academic Search

The late Guadalupian Bell Canyon Formation comprises alternating siltstone and fine to very fine-grained sandstone, which constitute economically important, shallow (2000-3000 ft, 600-900 m) oil reservoirs in the Delaware basin. In Ford-Geraldine field (Reeves and Culberson Counties), the Ramsey sandstone member, uppermost sand of the Bell Canyon Formation, was deposited in a deep-water, sediment-starved, euxinic basin. The Ford-Geraldine field produces

R. W. Ruggiero; A. J. Scott

1984-01-01

368

Numerical studies on flow fields around buildings in an Urban street canyon and cross-road  

Microsoft Academic Search

The questions on how vortices are constructed and on the relationship between the flow patterns and concentration distributions\\u000a in real street canyons are the most pressing questions in pollution control studies. In this paper, the very large eddy simulation\\u000a (VLES) and large eddy simulation (LES) are applied to calculate the flow and pollutant concentration fields in an urban street\\u000a canyon

Xueling Cheng; Fei Hu

2005-01-01

369

Street Versus Rooftop Level Concentrations of Fine Particles in a Cambridge Street Canyon  

Microsoft Academic Search

Dispersion of particles, as evidenced by changes in their number distributions (PNDs) and concentrations (PNCs), in urban\\u000a street canyons, is still not well understood. This study compares measurements by a fast-response particle spectrometer (DMS500)\\u000a of the PNDs and the PNCs (5–1000 nm, sampled at 1 Hz) at street and rooftop levels in a Cambridge UK street canyon, and examines\\u000a mixing, physical and

Prashant Kumar; Paul S. Fennell; Allan N. Hayhurst; Rex E. Britter

2009-01-01

370

Depositional environment of Canyon (Cisco) sandstones, North Jameson field Mitchell County, Texas  

E-print Network

helpful and I deeply appreciate his efforts. I also would. like to thank both Dr. Berg and my parents for all the financial support that each provided. I would like to thank Sun production Company and in particular, several of its employees... Canyon (Cisco) sandstones of Jameson (North) Strawn field, block 1-A, HATC Survey, Mitchell County, Texas. Contour interval 20 ft, (3 m). . Sedimentary structures in Canyon (Cisco) sandstones, Sun Stubhlefield A-1, Jameson (North) Strawn field...

Dally, David Jesse

2012-06-07

371

Rapid Formation of a Modern Bedrock Canyon by a Single Flood Event (Invited)  

NASA Astrophysics Data System (ADS)

Although ancient megafloods have carved some of the most spectacular canyons on Earth and Mars, quantifying flood discharge, duration and erosion mechanics is hampered because we lack modern analogs. Canyon Lake Gorge, Texas, was carved in 2002 during a single catastrophic flood event and offers a rare opportunity to analyze canyon formation and test paleo-hydraulic-reconstruction techniques under known topographic and hydraulic conditions. Here we use topography and imagery from before and after the flood, discharge measured during the event, field measurements, and sediment-transport modeling to show that the flood moved meter-sized boulders, excavated ~7 m of rock, and transformed a soil-mantled valley into a bedrock canyon in ~ 3 days. Canyon morphology is strongly dependent on rock type where plucking of limestone blocks produced waterfalls, inner channels and strath terraces, and 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, which greatly simplifies modeling and may improve hydraulic reconstructions of other megafloods on Earth and Mars.

Lamb, M. P.; Fonstad, M. A.

2010-12-01

372

Application of a lagrangian transport model to organo-mineral aggregates within the Nazaré canyon  

NASA Astrophysics Data System (ADS)

In this study, a hydrodynamic model was applied to the Nazaré submarine canyon with boundary forcing provided by an operational forecast model for the west Iberian coast for the spring of 2009. After validation, a lagrangian transport model was coupled to the hydrodynamic model to study and compare the transport patterns of three different classes of organo-mineral aggregates along the Nazaré canyon. The results show that the transport in the canyon is neither constant, nor unidirectional and that there are preferential areas where deposited matter is resuspended and redistributed. The transport of the larger class size of organo-mineral aggregates (2000 ?m and 4000 ?m) is less pronounced, and a decrease in the phytodetrital carbon flux along the canyon is observed. During the modelled period, the Nazaré canyon acts as a depocentre of sedimentary organic matter rather than a conduit of organo-mineral aggregates to the deep sea, as has been reported by other authors. The results of this study are crucial for the understanding of the oceanic carbon sequestration at the continental margin, and therefore important for evaluating the role of submarine canyons within the global carbon cycle.

Pando, S.; Juliano, M. F.; García, R.; Mendes, P. A. de Jesus; Thomsen, L.

2013-06-01

373

Stratigraphic framework and petroleum potential of northeastern Baltimore Canyon Trough, mid-Atlantic outer Continental Shelf  

SciTech Connect

Geologic data from 29 wells in the Baltimore Canyon Trough were released to the public as of 1982, and provide sufficient information for establishing Upper Jurasic through Cenozoic rock-stratigraphic units. Most of the units are lithologically similar to formations on the Scotian Shelf and are, therefore, considered in this study to be the Scotian Shelf homotaxial equivalents. The Mohawk(.) sandstone and Mic Mac shale equivalents in the Baltimore Canyon Trough represent lower delta plain to predominantly prodelta environments, and the Abenaki-equivalent limestone represents a shelf margin carbonate buildup. Inundation by the sea was incomplete, however, and channel and distributary-mouth-bar sands (Logan Canyon equivalent) were deposited. A final marine transgression began during the Late Cretaceous and resulted in the deposition of mudstone, which is considered equivalent to the Scotian Shelf Dawson Canyon Formation. Although both basins exhibit an upward increase in sand content, the Scotian Shelf Cenozoic strata are more sandy than those in the Baltimore Canyon Trough. Stratigraphic traps may be present in the Baltimore Canyon Trough Upper Jurassic and Lower Cretaceous deltaic sandstones and shelf-margin carbonates. The deltaic units contain channel and distributary-mount-bar sandstones, which may be potential reservoirs. Seals may be formed by lateral and vertical contacts against the prodelta, interdistributary bay, and marine shales. The Abenaki stratigraphic-reef trend provides another potential target. Source rocks, reservoir rocks, and traps may be associated with the trend, but its potential can only be defined by future drilling. 16 figures, 2 tables.

Libby-French, J.

1984-01-01

374

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

USGS Publications Warehouse

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)

Bowers, J.C.

1990-01-01

375

Stratigraphy and diagenesis of Sonora Canyon deep-water sandsontes, Val Verde basin, southwest Texas  

SciTech Connect

Several 'Canyon Sands' (Virgilian-Wolfcampian) intervals occur in the Val Verde basin, but the authors' study focuses on the Sonora Canyon, which is centered in western Sutton County. Sonora Canyon sandstones formed in continental-slope and basin-floor depositional systems basinward of a northwest-trending shelf margin. Well-log analysis revealed an overall wedgeshape geometry, thickening southwesterward from 500 ft at the shelf margin to 2000 ft where sandstone grades into basinal shale. The Sonora Canyon comprises coalesced submarine-fan systems forming a slope apron. Deltaic sandstones occur locally along the shelf margin, but mudstone covers most of the outer shelf. On the upper slope, channel-fill sandstones are discontinuous at 0.5- to 1.5-mi well spacing, and are enclosed in thick slope mudstones. Turbidites are the most prominent sedimentary features identified in Sonora Canyon cores. Channel-fill sandstones are massive to normally graded (Bouma divisions A and B) and are associated with slump and debris-flow facies. Sonora Canyon sandstones are mostly fine-grained to very fine-grained sublitharenites and litharenites. Chert, mudstone, sandstone, and low-rank metamorphic rock fragments are the predominant lithic grains. Major diagenetic events were (1) siderite and chlorite cementation, (2) mechanical compaction, (3) quartz cementation, (4) feldspar dissolution and illite and kaolinite precipitation, and (5) ankerite cementation. Intergranular porosity and permeability are higher in samples with abundant siderite cement because early precipitation of siderite inhibited later mechanical compaction and quartz cementation.

Hamlin, H.S.; Clift, S.J.; Dutton, S.P. (Univ. of Austin, TX (United States))

1992-04-01

376

Influence of the Nazaré Canyon, central Portuguese margin, on late winter coccolithophore assemblages  

NASA Astrophysics Data System (ADS)

This paper presents a first attempt to characterize coccolithophore assemblages occurring in the context of an active submarine canyon. Coccolithophores from the upper-middle sections of the Nazaré Canyon (central Portuguese margin) - one of the largest canyons of the European continental margin - were investigated during a late winter period (9-12 March 2010). Species distributions were analyzed in a multiparameter environmental context (temperature, salinity, turbidity, Chl-a and nutrient concentrations). Monthly averaged surface water Chl-a concentrations between 2006 and 2011 assessed from satellite data are also presented, as a framework for interpreting spatial and temporal distribution of phytoplankton in the Nazaré Canyon. The Nazaré Canyon was observed to act as a conduit for advection of relatively nutrient-poor oceanic waters of ENACWst origin into nearshore areas of the continental shelf (less than 10 km off the coast), whilst at the surface a nutrient-rich buoyant plume resulting from intensive coastal runoff prior and during the beginning of the cruise was spreading in oceanward direction. Two distinct coccolithophore assemblages appear representative for the coast to open-ocean gradient: (1) Emiliania huxleyi together with Gephyrocapsa ericsonii and Coronosphaera mediterranea dominated the more productive assemblage present within coastal-neritic surface waters; and (2) Syracosphaera spp. and Ophiaster spp. displayed a higher affinity with open-ocean conditions, and also generally a broader vertical distribution. Local “hotspots” of coccolithophore and phytoplankton biomass potentially associated with perturbations of surface water circulation by the canyon are discussed.

Guerreiro, Catarina; Sá, Carolina; de Stigter, Henko; Oliveira, Anabela; Cachão, Mário; Cros, Llu?sa; Borges, Carlos; Quaresma, Luis; Santos, Ana I.; Fortuño, José-Manuel; Rodrigues, Aurora

2014-06-01

377

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

USGS Publications Warehouse

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 Darwin Canyon Formations) representing part of a deep-water turbidite basin filled primarily by fine-grained siliciclastic sediment derived from cratonal sources to the east. Deformation and sedimentation along the western part of this basin continued into late Permian time. The culminating phase was part of a regionally extensive late Permian thrust system that included the Marble Canyon thrust fault just west of the present map area.

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

378

The Antarctic dry valley lakes: Relevance to Mars  

NASA Technical Reports Server (NTRS)

The similarity of the early environments of Mars and Earth, and the biological evolution which occurred on early Earth, motivates exobiologists to seriously consider the possiblity of an early Martian biota. Environments are being identified which could contain Martian life and areas which may presently contain evidence of this former life. Sediments which were thought to be deposited in large ice-covered lakes are present on Mars. Such localities were identified within some of the canyons of the Valles Marineris and more recently in the ancient terrain in the Southern Hemisphere. Perennially ice-covered Antarctic lakes are being studied in order to develop quantitative models that relate environmental factors to the nature of the biological community and sediment forming processes. These models will be applied to the Martian paleolakes to establish the scientific rationale for the exobiological study of ancient Martian sediments.

Wharton, R. A., Jr.; Mckay, Christopher P.; Mancinelli, Rocco L.; Clow, G. D.; Simmons, G. M., Jr.

1989-01-01

379

Effects of River Regulation on Aeolian Landscapes, Grand Canyon National Park, USA  

NASA Astrophysics Data System (ADS)

Sediment deposits in the Colorado River corridor include fluvial sandbars and aeolian dune fields, and the fluvial deposits are the primary sediment source for sand in the aeolian dunes. This 7-year study examined the effects of river regulation at Glen Canyon Dam (alteration of flow regime, sediment-supply reduction, and consequent loss of fluvial sandbars) on aeolian landscapes downstream in Grand Canyon National Park. A comparative study was developed between aeolian landscapes in Grand Canyon, Arizona, and Cataract Canyon, Utah, upstream of Glen Canyon Dam and its reservoir (Lake Powell), where hydrology and sediment supply of the Colorado River are affected substantially less by artificial river regulation than occurs in Grand Canyon. Before closure of Glen Canyon Dam in 1963, sediment-rich floods (mean annual peak 2400 m3/s) formed sandbars from which wind moved sand inland to form aeolian dunes. After dam operations reduced the amplitude and frequency of high flows, and eliminated the mainstream fluvial sediment supply, Grand Canyon’s fluvial sandbars lost open sand area owing to erosion by river flows and the spread of riparian vegetation. Two types of aeolian landscapes now occur in Grand Canyon: (1) modern fluvial sourced, those downwind of post-dam sandbars; and (2) relict fluvial sourced, whose primary sediment source was deposits from pre-dam floods that were larger than any post-dam flows have been. Sediment supply has been reduced to type (1) dune fields because post-dam sandbars are smaller than in the pre-dam era; new sediment supply to type (2) dune fields essentially has been eliminated. Type 1 aeolian landscapes can receive new windblown sand from sandbars formed by controlled floods (1160 m3/s), which occurred in 1996, 2004, and 2008. Type 1 dune fields, being downwind and within 100 m of controlled-flood sandbars, have significantly higher aeolian sand-transport rates, more open sand, and less biologic soil crust than relict type 2 dune fields. Type 1 aeolian landscapes in Grand Canyon have similar properties to the “near-natural” aeolian landscapes of Cataract Canyon that receive new windblown sand from fluvial sandbars left by annual sediment-rich floods, implying that controlled floods in Grand Canyon are effective at restoring some aeolian landscapes (as well as some fluvial sandbars) to near natural condition. These results provide strong evidence that anthropogenic river regulation affects landscape evolution even above the high water line, because of the link between fluvial deposition and aeolian transport of sediment. Effects of dam operations on aeolian landscapes include not only geomorphic and sedimentary systems, but also biological processes (development of soil crust and associated habitat). It is likely that, if current operations at Glen Canyon Dam (with occasional sediment-rich controlled floods) continue, greater differences in sand mobility, open sand area, biologic soil crust, and possibly vegetation will develop between modern and relict aeolian landscapes in Grand Canyon.

Draut, A. E.

2010-12-01

380

Geothermal data for 95 thermal and nonthermal waters of the Valles Caldera - southern Jemez Mountains region, New Mexico  

SciTech Connect

Field, chemical, and isotopic data for 95 thermal and nonthermal waters of the southern Jemez Mountains, New Mexico are presented. This region includes all thermal and mineral waters associated with Valles Caldera and many of those located near the Nacimiento Uplift, near San Ysidro. Waters of the region can be categorized into five general types: (1) surface and near surface meteoric waters; (2) acid-sulfate waters (Valles Caldera); (3) thermal meteoric waters (Valles Caldera); (4) deep geothermal and derivative waters (Valles Caldera); and (5) mineralized waters near San Ysidro. Some waters display chemical and isotopic characteristics intermediate between the types listed. The object of the data is to help interpret geothermal potential of the Jemez Mountains region and to provide background data for investigating problems in hydrology, structural geology, hydrothermal alterations, and hydrothermal solution chemistry.

Goff, F.; McCormick, Trujillo, P.E. Jr.; Counce, D.; Grigsby, C.O.

1982-05-01

381

Hydrogeochemical data for thermal and nonthermal waters and gases of the Valles Caldera- southern Jemez Mountains region, New Mexico  

SciTech Connect

This report presents field, chemical, gas, and isotopic data for thermal and nonthermal waters of the southern Jemez Mountains, New Mexico. This region includes all thermal and mineral waters associated with Valles Caldera and many of those located near the Nacimiento Uplift, north of San Ysidro. Waters of the region can be categorized into five general types: (1) surface and near-surface meteoric waters; (2) acid-sulfate waters at Sulphur Springs (Valles Caldera); (3) thermal meteoric waters in the ring fracture zone (Valles Caldera); (4) deep geothermal waters of the Baca geothermal field and derivative waters in the Soda Dam and Jemez Springs area (Valles Caldera); and (5) mineralized waters near San Ysidro. Some waters display chemical and isotopic characteristics intermediate between the types listed. Data in this report will help in interpreting the geothermal potential of the Jemez Mountains region and will provide background for investigating problems in hydrology, structural geology, hydrothermal alterations, and hydrothermal solution chemistry.

Shevenell, L.; Goff, F.; Vuataz, F.; Trujillo, P.E. Jr.; Counce, D.; Janik, C.J.; Evans, W.

1987-03-01

382

INCREASING OIL RECOVERY THROUGH ADVANCED REPROCESSING OF 3D SEISMIC, GRANT CANYON AND BACON FLAT FIELDS, NYE COUNTY, NEVADA  

Microsoft Academic Search

Makoil, Inc., of Orange, California, with the support of the U.S. Department of Energy has reprocessed and reinterpreted the 3D seismic survey of the Grant Canyon area, Railroad Valley, Nye County, Nevada. The project was supported by Dept. of Energy Grant DE-FG26-00BC15257. The Grant Canyon survey covers an area of 11 square miles, and includes Grant Canyon and Bacon Flat

Eric H. Johnson; Don E. French

2001-01-01

383

Anthropogenic trace metals in the sedimentary record of the Llobregat continental shelf and adjacent Foix Submarine Canyon (northwestern Mediterranean)  

Microsoft Academic Search

Anthropogenic trace-metal concentrations and inventories were studied on the Llobregat continental margin, from the Llobregat river mouth to the Foix submarine canyon. A prodelta sedimentary depocentre was identified along with a previously known canyon depocentre. Significant upward increases in trace-metal contents were detected in sediment cores of the prodelta and upper part of the canyon (down to 860 m depth). Metal

Albert Palanques; Pere Masqué; Pere Puig; Joan Albert Sanchez-Cabeza; Mauro Frignani; Francesca Alvisi

2008-01-01

384

Effects of trampling on in-stream macroinvertebrate communities from canyoning activity in the Greater Blue Mountains World Heritage Area  

Microsoft Academic Search

Perceived growth in the adventure recreation sport of canyoning in the Greater Blue Mountains World Heritage Area (Australia)\\u000a has raised concerns with park management that such activity is resulting in unsustainable visitor impacts to canyon ecosystems.\\u000a Three levels of trampling intensity were applied within an upland section of a canyon stream to assess the impact of trampling\\u000a on benthic macroinvertebrate

Nigel Hardiman; Shelley Burgin

2011-01-01

385

The 40Ar\\/39Ar age constraints on the duration of resurgence at the Valles caldera, New Mexico  

Microsoft Academic Search

The 40Ar\\/39Ar ages for rocks from the Valles caldera, New Mexico, imply that resurgent uplift of the caldera floor occurred within 27 ± 27 ka of caldera collapse. The structural resurgent dome of the Valles caldera was uplifted approximately 1000 m above the surrounding caldera floor during resurgence. The upper Bandelier Tuff, which yields an age of 1.256 ± 0.010

Erin H. Phillips; Fraser Goff; Philip R. Kyle; William C. McIntosh; Nelia W. Dunbar; Jamie N. Gardner

2007-01-01

386

Plio-Quaternary canyons evolution on South Colombian convergent margin : Tectonic causes and implications  

NASA Astrophysics Data System (ADS)

Investigations of seafloor morphology and sediment deposits associated with the incision of the South Colombia active margin by a major submarine canyon system are used to reveal out-of-sequence fault activity at least since the Middle Pleistocene. The South Colombian convergent margin is located along Northwestern South America, where the Nazca plate underthrusts eastward the South America plate with a 58 mm.yr-1 convergence rate. The morphology and deep multichannel seismic reflection lines obtained across the margin reflect a frontal accretionnary wedge, as well as antiform and faulted internal structural highs that locally extend up to near the continental shelf, suggesting wide-spread Plio-Quaternary tectonic activity. The Amadeus cruise conduced in 2005 brought new seismic and sedimentary data together with 150m and 60m-resolution EM12D multibeam bathymetry. The newly mapped Mira and Patia canyons system incises the South Colombian margin slope over a distance of ~90 and ~150 km respectively, forming an unequivocal Z-shape in map view, breaching the deformation front and feeding a 30-km wide trench fan system. The morphology of the canyon exhibits meanders, steep over-incised walls (~25-30 degrees), alternation between concave-up and convex-up downstream profiles, slope failures scars, and buried channels. These features reflect interactions between tectonics, sedimentation and the canyon evolution. A synthesis of all the data reveals that: A) Uplifting structural highs control canyons path and incision stages. B) Canyons developed asynchronously across the upper, mid and lower margin slopes according to three main stages: a) upper slope incision by downward cutting during Pleistocene, and possibly by retrogressive headward erosion, b) infill of a mid-slope basin bounded by uplifting structural highs, and c) overspill of the slope basin, and breaching its seaward bounding ridge, and the accretionary prism ~150 kyr ago. These processes led to the construction of sedimentary lobes in the trench, and then to a well-developed channel-levees system. C) Occurrences of antecedence, canyon walls over steepening, and convex-up bathymetric profiles of the canyons imply uplift of the fault-controlled structural highs at least during the last ~150 kyr supporting active out-of-sequence tectonic shortening. The long-term causes of the out-of-sequence tectonic could be linked to interplate coupling and basal friction variations. This study strongly reflects the interplay between tectonic deformation and canyon evolution thus providing a good example of the use of canyon morphology and associated deposits as markers of active tectonic deformation

Ratzov, Gueorgui; Sosson, Marc; Collot, Jean-Yves; Migeon, Sebastien

2010-05-01

387

Large-Eddy Simulation of Ventilation and Pollutant Removal in Neutrally and Unstably Stratified Street Canyons  

NASA Astrophysics Data System (ADS)

Large-eddy simulation model was developed to study the ventilation and pollutant removal of urban street canyons in neutral and unstable stratifications. Street canyons of unity building-height-to-street-width ratio were considered. For the case with unstable stratification, the ground was heated up to a Richardson number Rb (= gh/Uh2(?h-?0)/?ref) of -10, where g is the gravitational acceleration, h the building height, Uh the roof-level velocity scale, ?ref the reference temperature, ?h the roof-level temperature and ?0 the ground temperature. The gaseous pollutant was modeled as a passive scalar. Ground-level area sources with uniform pollutant concentrations were used to model traffic emission. In neutral stratification, skimming flow and poor pollutant removal are observed. A primary recirculation is developed in the street canyon core by the prevalent wind (Fig 1a). It occupies nearly all the space inside the street canyon leaving three small secondary recirculations at the ground-level leeward, ground-level windward and roof-level leeward corners. The pollutant emitted from the street is mostly trapped inside the street canyon hence elevated pollutant concentration is observed. Unstable stratification modifies the flow pattern significantly that enhances the pollutant removal. An enlarged secondary recirculation is observed at the ground-level windward corner (Fig 1b). It pushes the primary recirculation upward which eventually extends over the roof level of street canyon immersing into the shear layer aloft. The sizes of the two small recirculations on the leeward side shrink instead. The wind speed inside the street canyon increases that enhances the pollutant mixing. As a result, the overall pollutant concentration is lower compared with that in neutral stratification. In contrast to a roof-level thin layer of pollutant in neutral stratification, pollutant is carried upward by the convective updraft moving from the building roof level into the shear layer. Unstable stratification thus promotes pollutant dilution and removal in street canyons. Different locations of substantial turbulence kinetic energy (TKE) production were observed from the LES results of street canyons in neutral and unstable stratifications. In neutral stratification, TKE production is high at roof level because of the large velocity gradient there. In unstable stratification, because of the bottom heating, elevated TKE production locates near the windward facade. The large temperature gradient and the buoyancy force strengthen the recirculating wind at the ground-level windward corner. Therefore, the TKE production is peaked along the interface between the primary and secondary recirculations. Velocity and pollutant concentrations in a street canyon under: (a) neutral and (b) unstable stratifications.

Liu, C.; Cheng, W.; Leung, D. Y.

2009-12-01

388

Lateral advection of organic matter in cascading-dominated submarine canyons  

NASA Astrophysics Data System (ADS)

In the Gulf of Lions (GoL), dense water overflowing off the shelf occurs seasonally and represents the main mechanism affecting the shelf-slope exchange of particulate organic matter (OM). Most of the dense water export takes place in the south-western GoL and in particular through Cap de Creus (CdC) submarine canyon. Here, benthic instruments were deployed to collect down-canyon particulate fluxes whereas surface sediments were taken after the cascading event along the sediment dispersal system on the shelf, in CdC canyon and in the nearby Lacaze-Duthiers (LD) canyon. The chemical composition of the suspended material and surface sediments were investigated using several proxies including organic and inorganic carbon, total nitrogen, biogenic silica, ? 13C, ? 14C, and alkaline CuO oxidation products. Thermohaline anomalies and high current speed events were measured in CdC canyon since December 2004 until mid-April 2005 indicating a marked off-shelf export of dense water trough the canyon. During the cascading, mud and relatively coarse shelf and upper canyon sediments were the major component of the mass flux. Conversely, advection of fine material via nepheloid layers dominated down-slope fluxes during pre- and post-cascading. The resulting change in grain-size affected the flux of mineral-bound terrigenous OC, indicating that the down-canyon transport of land-derived OM did not occur as bulk but rather its composition is driven by sediment sorting associated with different transport mechanisms. Both surface sediments and sediment trap samples indicated that CdC canyon is well connected to the GoL terrigenous dispersal system. Conversely, our results suggest an overall limited influence of land-derived OM in LD canyon. In spite of the reduced fluvial nutrient supply, a significant pulsed input of modern marine OM was observed in April 2005 at the end of the cascading period. Both intense mixing and lack of strong water column stratification likely played a key role allowing for both diffusion of nutrients-rich waters into the euphotic zone and efficient vertical sink of marine OC. On its way toward the seafloor, this fresh pool of OC interacted with the dense plume overflowing off the shelf, becoming part of the material laterally advected to the slope.

Tesi, T.; Puig, P.; Palanques, A.; Goñi, M. A.

2010-03-01

389

Sedimentary regime of deep submarine canyons around Fylla Banke, northeastern Labrador Sea  

NASA Astrophysics Data System (ADS)

Sedimentary regime of deep submarine canyons around the Fylla Banke, northeastern Labrador Sea Dorthe Paulsen (1), Antoon Kuijpers (2), Marit-Solveig Seidenkrantz (3) and Tove Nielsen (2) 1) Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K 2) Geological Survey of Denmark and Greenland (GEUS), Øster Voldgde 10, DK-1350 Copenhagen K. 3) Centre for Past Climate Studies, Department of Geoscience, Aarhus University. Hoegh-Guldbergs Gade 2, DK-8000 Aarhus C The southern end of the Davis Strait, the comparatively shallow-water area separating the Labrador Sea from the Baffin Bay, is cut by two deep submarine canyons of west Greenland, on the western and eastern side of the Fylla Banke, respectively. The purpose of this study is to investigate Late Pleistocene sedimentary processes governing the area of the two canyons in order to test if gravity flows or ocean currents are the most important factors governing canyon sedimentary processes in this region. Furthermore, an account is given on the formation of the two canyons in order to explain the significant difference between them. The study was carried out based on seismic profiles combined with bathymetric information, and a single sidescan sonar profile from one of the canyons (western canyon). Sedimentary information and an age model are derived from of a 5-m long gravity core (TTR13-AT-479G) collected from the mouth of the western canyon (southern end). The data indicates that the sedimentary regime is today highly affected by northward transport of the ocean currents and that gravity flows (southward from shallower to deep waters) are only of limited significance today. The deep southern end of the canyons are influenced by the upper parts of the deep North Atlantic Deep Water, but the majority of the sediment transport is linked to the strong northward flow of the lower parts of the West Greenland Current. For comparison the sediment transport is held up against earlier studies from the Davis Strait area, where 2D seismic profiles were carried out several places of the west coast of Greenland. These studies are from a contourite drift complex at the Davis Strait and north of Labrador Sea. A further possible process operating in maintaining active sediment transport through the canyon may be the cascading of dense winter water formed on the West Greenland shelf.

Paulsen, Dorthe; Kuijpers, Antoon; Seidenkrantz, Marit-Solveig; Nielsen, Tove

2014-05-01

390

Physical experiments to investigate the effects of street bottom heating and inflow turbulence on urban street-canyon flow  

NASA Astrophysics Data System (ADS)

The effects of street bottom heating and inflow turbulence on urban street-canyon flow are experimentally investigated using a circulating water channel. Three experiments are carried out for a street canyon with a street aspect ratio of 1. Results from each experiment with bottom heating or inflow turbulence are compared with those without bottom heating and appreciable inflow turbulence. It is demonstrated that street bottom heating or inflow turbulence increases the intensity of the canyon vortex. A possible explanation on how street bottom heating or inflow turbulence intensifies the canyon vortex is given from a fluid dynamical viewpoint.

Kim, Jae-Jin; Baik, Jong-Jin

2005-03-01

391

Sediment transport along the Cap de Creus Canyon flank during a mild, wet winter  

NASA Astrophysics Data System (ADS)

Cap de Creus Canyon (CCC) is known as a preferential conduit for particulate matter leaving the Gulf of Lion continental shelf towards the slope and the deep basin, particularly in winter when storms and dense shelf water cascading coalesce to enhance the seaward export of shelf waters. During the CASCADE (CAscading, Storm, Convection, Advection and Downwelling Events) cruise in March 2011, deployments of recording instruments within the canyon and vertical profiling of the water column properties were conducted to study with high spatial-temporal resolution the impact of such processes on particulate matter fluxes. In the context of a mild and wet 2010-2011 winter, no remarkable dense shelf water formation was observed. On the other hand, the experimental setup allowed to study the impact of E-SE storms on the hydrographical structure and the particulate matter fluxes in the CCC. The most remarkable feature in terms of sediment transport was a period of dominant E-SE winds from 12 to 16 March, including two moderate storms of significant wave heights = 4-4.5 m. During this period, a plume of freshened, relatively cold and turbid water flowed at high speeds along the southern flank of CCC in an approximate depth range of 150-350 m. The density of this water mass only reached ~ 28.78 kg m-3, indicating that it did not cascade into the canyon and that merely downwelled into it forced by the accumulation of seawater along the coast during the storms and by the subsequent strong cyclonic circulation induced over the shelf. Suspended sediment load in this turbid intrusion was comparable at three heights above bottom where turbidimeters were installed (10, 75 and 115 m above bottom) on the southern canyon flank and oscillated between 10 and 50 mg L-1. Current speeds were also comparable in the depth range profiled by ADCPs (40 to 150 mab) and reached values up to 90 cm s-1 during the peak of the strongest storm (13 March, Hs = 4.5 m). Sediment transport at 75 mab on the southern canyon flank was estimated at 1-1.5 t m-2 for the entire deployment while very close to the bottom (5 m above) in the canyon head it was less than 0.6 t m-2 during the same period. We provide a rough estimation of 105 t of sediment transported through the canyon along its southern wall during a 3 day-long period of storm-induced downwelling. Following the veering of the wind direction (from SE to NW) on 16 March, downwelling ceased, currents inside the canyon reversed from down to up-canyon, and the turbid shelf plume was evacuated from the canyon, most probably flowing along the southern canyon flank and being entrained by the general SW circulation after leaving the canyon confinement. This study highlights that remarkable sediment transport occurs in the CCC, and particularly along its southern flank, even during mild and wet winters, in absence of cascading and under limited external forcing. The sediment transport associated to eastern storms like the ones described in this paper tends to enter the canyon by its downstream flank, partially affecting the canyon head region. Sediment transport during these events is not constrained near the seafloor but distributed in a depth range of 200-300 m above the bottom. Our paper broadens the understanding of the complex set of atmosphere-driven sediment transport processes acting in this highly dynamic area of the northwestern Mediterranean Sea.

Martín, J.; Durrieu de Madron, X.; Puig, P.; Bourrin, F.; Palanques, A.; Houpert, L.; Higueras, M.; Sanchez-Vidal, A.; Calafat, A. M.; Canals, M.; Heussner, S.

2012-12-01

392

The Grand Canyon Monitoring and Research Center's Role in Colorado River Ecosystem Science Below Glen Canyon Dam: An Overview on Science-Based River Management  

Microsoft Academic Search

Impacts of Glen Canyon Dam (GCD) operations on downstream resources have been intensively studied by scientists and engineers since the early 1970s. In 1989, the Secretary of the Interior directed the Bureau of Reclamation to conduct the first-ever retroactive environmental compliance on operations of a large dam. Studies focused on linkages between flows and depletion of sand bars, endangered species

D. B. Fenn; T. S. Melis

2002-01-01

393

Effects of the Post-Glen Canyon Dam Flow Regime on the Old High Water Line Plant Community Along the Colorado River in Grand Canyon.  

National Technical Information Service (NTIS)

Growth and reproduction of native riparian trees were studied along the Colorado River in Grand Canyon. Populations of mesquite and acacia in the old high water zone were found to be growing and reproducing successfully. Shoot growth in adults is not sign...

L. S. Anderson, G. A. Ruffner

1987-01-01

394

Temporal and spatial variation in the Nazaré Canyon (Western Iberian margin): Inter-annual and canyon heterogeneity effects on meiofauna biomass and diversity  

NASA Astrophysics Data System (ADS)

The Nazaré Canyon on the Portuguese Margin (NE Atlantic) was sampled during spring-summer for three consecutive years (2005-2007), permitting the first inter-annual study of the meiofaunal communities at the Iberian Margin at two abyssal depths (~3500 m and ~4400 m). Using new and already published data, the meiofauna standing stocks (abundance and biomass) and nematode structural and functional diversity were investigated in relation to the sediment biogeochemistry (e.g. organic carbon, nitrogen, chlorophyll a, phaeopigments) and grain size. A conspicuous increase in sand content from 2005 to 2006 and decrease of phytodetritus at both sites, suggested the occurrence of one or more physical disturbance events. Nematode standing stocks and trophic diversity decreased after these events, seemingly followed by a recovery/recolonisation period in 2007, which was strongly correlated with an increase in the quantity and bioavailability of phytodetrital organic matter supplied. Changes in meiofauna assemblages, however, also differed between stations, likely because of the contrasting hydrodynamic and food supply conditions. Higher meiofauna and nematode abundances, biomass and trophic complexity were found at the shallowest canyon station, where the quantity, quality and bioavailability of food material were higher than at the deeper site. The present results suggest that even though inter-annual variations in the sedimentary environment can regulate the meiofauna in the abyssal Nazaré Canyon, heterogeneity between sampling locations in the canyon were more pronounced.

Ramalho, Sofia P.; Adão, Helena; Kiriakoulakis, Konstadinos; Wolff, George A.; Vanreusel, Ann; Ingels, Jeroen

2014-01-01

395

The Hydrothermal System at the Grand Canyon of the Yellowstone River: Exposed and Hidden  

NASA Astrophysics Data System (ADS)

Combining calibrated and corrected night-time, airborne thermal infrared imaging with field information from the 2008 drilling of the Canyon borehole strainmeter (B206) in Yellowstone National Park emphasizes the extensive nature of Yellowstone's hydrothermal system. Both studies contributed to an understanding of the vertical and horizontal flow of heat and fluids through the bedrock in this area. Night-time, airborne thermal infrared imagery, corrected for emissivity and atmosphere clearly shows north-trending faults and fractures transmitting heat and fluids through the rhyolitic bedrock and into the overlying glacial sediments near the Canyon borehole. Along the Grand Canyon of the Yellowstone, the Clear Lake hydrothermal area is an example of hydrothermal alteration at the ground surface. The numerous hydrothermal features exposed in the nearby Grand Canyon of the Yellowstone River and its hydrothermally altered walls are clear evidence of the exposed hydrothermal system. The bedrock geology, geologic processes, and hydrothermal activity combined to form the dramatic Grand Canyon of the Yellowstone. The night-time thermal infrared imagery provides a new view of this exposed hydrothermal system for scientists and visitors. Scientists and Yellowstone Park managers carefully sited the Canyon borehole strainmeter in a green, grassy meadow to insure successful completion of the borehole in a non-hydrothermal area. The closest hydrothermal feature to the drilling site was about 2.5 km to the east. Although excellent exposures of hydrothermal altered bedrock are present about 1.5 km east at the Lower Falls and the Grand Canyon of the Yellowstone River, the connection between exposed hydrothermal areas and the borehole site was not obvious. After drilling through 9 m of brown-gray muds and 113 m of rock, a bottom hole temperature of 81.2 degrees Celsius precluded drilling the hole any deeper than 122 m. The post-drilling data collected from B206 and the airborne thermal infrared imagery clearly show that Yellowstone's hydrothermal system is larger than its surface expression.

Jaworowski, C.; Heasler, H. P.; Susong, D. D.; Neale, C. M.; Sivarajan, S.; Masih, A.

2012-12-01

396

Reconstruction of submarine canyon systems associated with proto-Stockton arch during Late Cretaceous  

SciTech Connect

A hypothetical depositional model of the middle Great Valley gas fields of California includes the area from the Southwest Vernalis gas field in the south (T3S) to the Nicolaus gas field in the north (T12N). The model assumes that (1) the early Campanian Dobbins Shale Member was deposited at or near the shelf/slope break, and (2) the absence of the Dobbins Shale Member indicates scouring processes of active submarine canyon systems. A striking correlation exists between the proposed distribution of the Dobbins Shale Member scour channels and the position of river systems operating today in the valley. The model distinguishes six submarine canyon systems: (1) Feather River/Nicolaus, (2) American River/Florin, (3) Cosumnes River/Poppy Ridge, (4) Mokelumne River/Lodi, (5) Calaveras delta/Mulligan Hill, and (6) Stanislaus River/East Collegeville. The model implies that an extensive delta system was associated with the Calaveras River during deposition of the Dobbins Shale Member, before its erosive exit southwest of the Mulligan Hill gas field, just east of the Los Medanos, Concord, and Willow Pass fields. The presence of possible equivalents of the Dobbins Shale Member of this latter area suggests an early Campanian highland, the proto-Stockton arch. Subsequent Forbes Formation deposition appears to involve apronlike drapes or overlaps of the early Campanian canyons. However, during deposition of the Kione Formation, the canyon systems were reactivated, and canyon scour predominated, matching the scour patterns of the Dobbins Shale Member. From these ancestral canyons, younger canyons could have evolved easily.

Rider, J.

1986-04-01

397

Calcareous nannoplankton and benthic foraminiferal assemblages from the Nazaré Canyon (Portuguese continental margin): Preliminary results  

NASA Astrophysics Data System (ADS)

Submarine canyons are assumed to play an important role in oceanic/neritic circulation, marine productivity and sedimentary processes, acting as preferential conduits between the littoral and deep oceanic domain. Here we present first results of a comparative micropalaeontological study on calcareous nannoplankton and benthic foraminifera from surface sediments from the surroundings of the upper Nazaré Canyon (Portuguese continental margin) and from the shelf north of the canyon. Regardless of the difficulty to distinguish taphonomical from (palaeo)ecological effects in such a complex and still poorly known marine system, the first results suggest that the canyon's hydro-sedimentary dynamic regime act as a prolongation of the shore/inner shelf hydrodynamic conditions towards west, preventing deposition and/or preservation of the smaller and fragile species of calcareous nannoplankton (e.g. E. huxleyi and G. ericsonii) and enhancing the record of the larger and more opportunistic ones (e.g. G. oceanica); and disturbing benthic foraminiferal productivity and/or diversity, or their preservation in the fossil record. Both calcareous nannoplankton and benthic foraminifera are more abundant off the canyon's domain, suggesting that its highly energetic thalweg conditions are probably filtering the fossil record in the sediment. Still, preliminary results suggest that the occurrence of persistent physical phenomena related with the canyon's morphology and proximity to the coast (e.g. solitary internal waves) may be locally promoting favourable conditions for calcareous nannoplankton, as shown by high values of nannoliths, chlorophyll a and 19' hexanoyloxyfucoxantine (unpublished data) north of the canyon's head. It is our goal to test this hypothesis in the near future by (a) studying multicore and surficial sediments from more recent surveys, and (b) calibrating the sediment results with water column data presently in process at the Institute of Oceanography (IO).

Guerreiro, C.; Rosa, F.; Oliveira, A.; Cachão, M.; Fatela, F.; Rodrigues, A.

2009-01-01

398

Constraining the timing of turbidity current driven sediment transport down Monterey Canyon, offshore California  

NASA Astrophysics Data System (ADS)

Turbidity currents are responsible for transport of sand down the Monterey Submarine Canyon, offshore California, from the shoreline to Monterey Fan. However the timing of sediment transport events and their frequencies are not fully understood despite recent monitoring of canyon events and AMS 14C dating of foraminifera from hemipelagic sediments bracketing sand deposited during turbidity flows. Quartz optically stimulated luminescence (OSL) dating in sand sequences provides a complementary means of dating sand transport. OSL dates reflect the time interval since the sand grains were last exposed to sunlight. However, the technique has never been applied extensively to canyon sediments before. Here we report both quartz OSL ages of sand deposits and benthic foraminifera ages sampled from the axial channel within Monterey Submarine Canyon and Fan via ROV-collected vibracores. This allows a rare opportunity to directly test the frequency and timing of turbidity current events at different points in the canyon. We use both single-grain and small (~2 mm area) single aliquot regeneration OSL approaches on vibracore samples from various water depths to determine sand transport frequency. Within the upper canyon (<2,000 m water depths) the OSL data require sub-decadal to decadal transit times. Sand bearing fining upward sequences yielding middle Holocene to last few hundred year ages indicate turbidity currents occur at 150 to 250 year event frequencies within the fan channel out to 3,600 m water depth. We suggest that turbidity currents have been active during the current sea-level high stand and that the submarine fan has recorded turbidity currents over the entire Holocene. The increased age spread in single grain OSL dates with water depth provides evidence of sediment mixing and reworking during turbidity flows. Apparently, sand is stored within the canyon for various amounts of time while it is in route to its current location on the fan.

McGann, M.; Stevens, T.; Paull, C. K.; Ussler, W.; Buylaert, J.

2013-12-01

399

Effects of building roof greening on air quality in street canyons  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

400

Magmatic Recharge during the Formation and Resurgence of theValles Caldera, New Mexico,  

E-print Network

: Evidence from Quartz Compositional Zoning and Geothermometry JACK WILCOCK1 , FRASER GOFF2 , WILLIAM G- ized by eruption of two voluminous high-silica rhyolite ignimbrites, the Otowi and Tshirege Members stratigraphic horizons of the UBT ignimbrite, (2) samples of the Deer Canyon Rhyolite and (3) the Cerro del

Minarik, William

401

Clustered streamlined forms in Athabasca Valles, Mars: Evidence for sediment deposition during floodwater ponding  

USGS Publications Warehouse

A unique clustering of layered streamlined forms in Athabasca Valles is hypothesized to reflect a significant hydraulic event. The forms, interpreted as sedimentary, are attributed to extensive sediment deposition during ponding and then streamlining of this sediment behind flow obstacles during ponded water outflow. These streamlined forms are analogous to those found in depositional basins and other loci of ponding in terrestrial catastrophic flood landscapes. These terrestrial streamlined forms can provide the best opportunity for reconstructing the history of the terrestrial flooding. Likewise, the streamlined forms in Athabasca Valles may provide the best opportunity to reconstruct the recent geologic history of this young Martian outflow channel. ?? 2005 Elsevier B.V. All rights reserved.

Burr, D.

2005-01-01

402

Sediment transport along the Cap de Creus Canyon flank during a mild, wet winter  

NASA Astrophysics Data System (ADS)

Cap de Creus Canyon (CCC) is known as a preferential conduit for particulate matter leaving the Gulf of Lion continental shelf towards the slope and the basin, particularly in winter when storms and dense shelf water cascading coalesce to enhance the seaward export of shelf waters. During the CASCADE (CAscading, Storm, Convection, Advection and Downwelling Events) cruise in March 2011, deployments of recording instruments within the canyon and vertical profiling of the water column properties were conducted to study with high spatial-temporal resolution the impact of such processes on particulate matter fluxes. In the context of the mild and wet 2010-2011 winter, no remarkable dense shelf water formation was observed. On the other hand, the experimental setup allowed for the study of the impact of E-SE storms on the hydrographical structure and the particulate matter fluxes in the CCC. The most remarkable feature in terms of sediment transport was a period of dominant E-SE winds from 12 to 16 March, including two moderate storms (maximum significant wave heights = 4.1-4.6 m). During this period, a plume of freshened, relatively cold and turbid water flowed at high speeds along the southern flank of the CCC in an approximate depth range of 150-350 m. The density of this water mass was lighter than the ambient water in the canyon, indicating that it did not cascade off-shelf and that it merely downwelled into the canyon forced by the strong cyclonic circulation induced over the shelf during the storms and by the subsequent accumulation of seawater along the coast. Suspended sediment load in this turbid intrusion recorded along the southern canyon flank oscillated between 10 and 50 mg L-1, and maximum currents speeds reached values up to 90 cm s-1. A rough estimation of 105 tons of sediment was transported through the canyon along its southern wall during a 3-day-long period of storm-induced downwelling. Following the veering of the wind direction (from SE to NW) on 16 March, downwelling ceased, currents inside the canyon reversed from down- to up-canyon, and the turbid shelf plume was evacuated from the canyon, most probably flowing along the southern canyon flank and being entrained by the general SW circulation after leaving the canyon confinement. This study highlights that remarkable sediment transport occurs in the CCC, and particularly along its southern flank, even during mild and wet winters, in absence of cascading and under limited external forcing. The sediment transport associated with eastern storms like the ones described in this paper tends to enter the canyon by its downstream flank, partially affecting the canyon head region. Sediment transport during these events is not constrained near the seafloor but distributed in a depth range of 200-300 m above the bottom. Our paper broadens the understanding of the complex set of atmosphere-driven sediment transport processes acting in this highly dynamic area of the northwestern Mediterranean Sea.

Martín, J.; Durrieu de Madron, X.; Puig, P.; Bourrin, F.; Palanques, A.; Houpert, L.; Higueras, M.; Sanchez-Vidal, A.; Calafat, A. M.; Canals, M.; Heussner, S.; Delsaut, N.; Sotin, C.

2013-05-01

403

Sediment transport along the Cap de Creus Canyon flank during a mild, wet winter  

NASA Astrophysics Data System (ADS)

Cap de Creus Canyon (CCC) is known as a preferential conduit for particulate matter leaving the Gulf of Lion continental shelf towards the slope and the deep basin, particularly in winter when storms and dense shelf water cascading coalesce to enhance the seaward export of shelf waters. During the CASCADE (CAscading, Storm, Convection, Advection and Downwelling Events) cruise in March 2011, deployments of recording instruments and vertical profiling of the water column properties were conducted to study with high spatial-temporal resolution the impact of such processes on particulate matter fluxes along the CCC. The most remarkable feature in terms of sediment transport was a period of dominant E-SE winds from 12 to 16 March, including two moderate storms of significant wave heights = 4-4.5 m. During this period, a plume of freshened, relatively cold and turbid water flowed at high speeds along the southern flank of CCC in an approximate depth range of 150-350 m. The density of this water mass only reached ~ 28.78 kg m-3, indicating that it did not cascade into the canyon and that merely downwelled into it forced by the accumulation of seawater along the coast during the storms and by the subsequent strong cyclonic circulation induced over the shelf. Suspended sediment load in this turbid intrusion was comparable at three heights above bottom where turbidimeters were installed (10, 75 and 115 meters above bottom) on the southern canyon flank and oscillated between 10 and 50 mg l-1. Current speeds were also comparable in the depth range profiled by ADCPs (40 to 150 mab) and reached values up to 90 cm s-1 during the peak of the strongest storm (13 March, Hs = 4.5 m). Sediment transport at 75 mab on the southern canyon flank was estimated at 1-1.5 ton m-2 for the entire deployment while very close to the bottom (5 m above) in the canyon head it was less than 0.6 ton m-2 during the same period. We provide a rough estimation of 105 tons of sediment transported through the canyon along its southern wall during a 3 day-long period of storm-induced downwelling. Following the veering of the wind direction (from SE to NW) on 16 March, downwelling ceased, currents inside the canyon reversed from down to up-canyon, and the turbid shelf plume was evacuated from the canyon, most probably flowing along the southern canyon flank and being entrained by the general SW circulation after leaving the canyon confinement. This study highlights that remarkable sediment transport occurs in the CCC, and particularly along its southern flank, even during mild and wet winters, in absence of cascading and under limited external forcing. The sediment transport associated to eastern storms like the ones described in this paper tends to enter the canyon by its downstream flank, partially affecting the canyon head region. Sediment transport during these events is not constrained near the seafloor but distributed in a depth range of 200-300 meters above the bottom.

Martín, Jacobo; Durrieu de Madron, Xavier; Puig, Pere; Bourrin, François; Palanques, Albert; Houpert, Loic; Higueras, Marina; Sanchez-Vidal, Anna; Calafat, Antoni M.; Canals, Miquel; Heussner, Serge

2013-04-01

404

Stratigraphic and structural controls on fluorspar mineralization in northern Valle Las Norias, Coahuila, Mexico  

E-print Network

rock were analysed using petrography and scanning electron micro- scopy (SEM). Fluorspar boundary zones were analysed using SEM/micro- probe wavelength dispersive analysis. In general, it was determined that fluorspar zones are associated... Fluorspar in Valle Las Norias 15 17 19 19 21 PROCEDURES 23 Field Procedures. 23 Laboratory Procedures 23 RESULTS. 26 Mapping Pico Etereo Measured Section. 26 40 Sedimentary Petrology Fluorspar Petrology SEM: Secondary Electron Imagery...

Rapport, Eric John

2012-06-07

405

Andesite and dacite genesis via contrasting processes: the geology and geochemistry of El Valle Volcano, Panama  

Microsoft Academic Search

The easternmost stratovolcano along the Central American arc is El Valle volcano, Panama. Several andesitic and dacitic lava\\u000a flows, which range in age 5–10 Ma, are termed the old group. After a long period of quiescence (approximately 3.4 Ma), volcanic\\u000a activity resumed approximately 1.55 Ma with the emplacement of dacitic domes and the deposition of dacitic pyroclastic flows\\u000a 0.9–0.2 Ma.

Mare J. Defant; Lee F. Clark; Robert H. Stewart; Mark S. Drummond; Jelle Z. de Boer; René C. Maury; Hervé Bellon; Thomas E. Jackson; Juan F. Restrepo

1991-01-01

406

Couper l'eau d'un canal d'irrigation dans la valle peut  

E-print Network

Couper l'eau d'un canal d'irrigation dans la vallée peut être passible de la plus lourde amende : 400 dirhams contre 25 dirhams pour la non-participation à l'entretien des canaux d'irrigation. Réunion définition des tâches de maintenance des infrastructures d'irrigation sont soumises à une organisation

407

Couper l'eau d'un canal d'irrigation dans la valle peut  

E-print Network

Couper l'eau d'un canal d'irrigation dans la vallée peut être passible de la plus lourde amende : 400 dirhams contre 25 dirhams pour la non-participation à l'entretien des canaux d'irrigation. Les non irrigants, ont changé l'organisation territoriale de l'irrigation. Le système de gestion de l'irrigation

408

Hudson Submarine Canyon Head Offshore New York and New Jersey: A Dynamic Interface  

NASA Astrophysics Data System (ADS)

Hudson Canyon is the largest submarine canyon on the U. S. Atlantic continental margin. Having completed a surface ship multi-beam bathymetric map of the Hudson Canyon region (resolution 100m; http://pubs.usgs.gov/of/2004/1441/index/html), we report preliminary results of mapping portions of the canyon head (75 square km, water depth 200-500 m) using the Eagle Ray autonomous underwater vehicle (Explorer 27- BO1-2200 AUV, ISE Ltd.) of the University of Southern Mississippi. The AUV was equipped with a Simrad EM2000 multi-beam sonar system and flown 50 m above the seafloor for resolution (3 m), and with a CTD to map water column properties. Shipboard CTD casts were also made and water sampled from the shelf break (depth 200 m) to the upper continental rise (3000 m) for detection of methane. The canyon head is of interest as an essential fish habitat (squid, hake, tilefish, and lobster) that may contribute to sustain a regional fishery and that may conduct sediment to the ocean basin. A shallow trough, the Hudson Shelf Valley, extends ~185 km across the continental shelf connecting the mouth of the Hudson River to the canyon head where it indents the seaward edge of the shelf. The canyon head bifurcates with branch 1 (6 km-long) oriented NW-SE aligned with the Shelf Valley, and branch 2 (4 km-long) oriented N-S. The two branches merge into a segment 10 km-long oriented NW-SE aligned with branch 1. Branch 1 has symmetric walls with mean inclinations of 10 degrees and smooth seafloor, suggesting that it is presently inactive and accumulating a cover of hemipelagic sediment. In contrast, the walls of both the N-S branch 2 and of the contiguous NW-SE segment are asymmetric. The walls of the NW-SE segment have a mean inclination of 15 degrees and exhibit semicircular escarpments 800-900 m long and 600-700 m wide, separated by narrow ravines perpendicular to the canyon axis. Slump blocks with sharp rims occur where N-S branch 1 joins the NW- SE segment. Two circular depressions (diameter 100 and 300 m; relief c.15 m; depths 345 m and 390 m) occur at the base of the SW wall of the segment and may be collapse features related to gas discharge evidenced by a high methane anomaly at the shelf edge. The head of Hudson Canyon encompasses diverse habitats and is a dynamic interface between shelf and slope processes. We thank NOAA's National Undersea Research Program for support.

Rona, P.; Guida, V.; Sullivan, M.; Haag, S.; Macelloni, L.; Sweeney, E.; Scranton, M.; Hobbs, J.; Asper, V.

2007-12-01

409

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

NASA Astrophysics Data System (ADS)

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, diversity and community structure of the macrofauna are discussed. It is suggested that altered and localised environmental conditions in the Portuguese canyons play an important role in modifying more common abundance and diversity bathymetric patterns evident in many continental slope environments.

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

410

The Jurassic section along McElmo Canyon in southwestern Colorado  

USGS Publications Warehouse

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.

O'Sullivan, Robert B.

1997-01-01

411

A comparison of megafaunal communities in five submarine canyons off Southern California, USA  

NASA Astrophysics Data System (ADS)

Remotely operated vehicle surveys were conducted in five submarine canyons off Southern California during research expeditions in 2005 and 2010. Video transects from a range of depths were analysed to produce presence/absence data of megafauna for each site. A comparison of benthic communities at various depths, locales, and canyons was performed. No significant difference was found between canyon communities based on the level of sediment transport activity, however this may be due to the unbalanced sampling of this opportunistic study. There was significant variation in biological community composition and abundance amongst water depths. These depth-related trends are in agreement with the findings of the previous studies and are likely tied to depth-correlated variables such as hydrostatic pressure, temperature, salinity, and oxygen concentration. Species richness was found to initially increase with depth before declining rapidly at the mouths of the studied canyons. Low oxygen levels in the Santa Monica Basin, into which four of the surveyed canyons empty, may explain this.

Duffy, Grant A.; Lundsten, Lonny; Kuhnz, Linda A.; Paull, Charles K.

2014-06-01

412

Long-term surveillance plan for the Burro Canyon disposal cell, Slick Rock, Colorado  

SciTech Connect

This long-term surveillance plan (LTSP) describes the US Department of Energy (DOE) long-term care program for the Uranium Mill Tailings Remedial Action (UMTRA) Project Burro Canyon disposal cell in San Miguel County, Colorado. The US Nuclear Regulatory Commission (NRC) developed regulations for the issuance of a general license for the custody and long-term care of UMTRA Project disposal sites in 10 CFR Part 40. The purpose of this general license is to ensure that the UMTRA Project disposal sites are cared for in a manner that protects the public health and safety and the environment. Before each disposal site is licensed, the NRC requires the DOE to submit a site-specific LTSP. The DOE prepared this LTSP to meet this requirement for the Burro Canyon disposal cell. The general license becomes effective when the NRC concurs with the DOE`s determination that remedial action is complete at the Burro Canyon disposal cell and the NRC formally accepts this LTSP. Attachment 1 contains the concurrence letters from NRC. This LTSP describes the long-term surveillance program the DOE will implement to ensure that the Burro Canyon disposal cell performs as designed. The program is based on site inspections to identify threats to disposal cell integrity. Ground water monitoring will not be required at the Burro Canyon disposal cell because the ground water protection strategy is supplemental standards based on low yield from the uppermost aquifer.

NONE

1998-05-01

413

A Double-Canyon Radiation Scheme for Multi-Layer Urban Canopy Models  

NASA Astrophysics Data System (ADS)

We develop a double-canyon radiation scheme (DCEP) for urban canopy models embedded in mesoscale numerical models based on the Building Effect Parametrization (BEP). The new scheme calculates the incoming and outgoing longwave and shortwave radiation for roof, wall and ground surfaces for an urban street canyon characterized by its street and building width, canyon length, and the building height distribution. The scheme introduces the radiative interaction of two neighbouring urban canyons allowing the full inclusion of roofs into the radiation exchange both inside the canyon and with the sky. In contrast to BEP, we also treat direct and diffuse shortwave radiation from the sky independently, thus allowing calculation of the effective parameters representing the urban diffuse and direct shortwave radiation budget inside the mesoscale model. Furthermore, we close the energy balance of incoming longwave and diffuse shortwave radiation from the sky, so that the new scheme is physically more consistent than the BEP scheme. Sensitivity tests show that these modifications are important for urban regions with a large variety of building heights. The evaluation against data from the Basel Urban Boundary Layer Experiment indicates a good performance of the DCEP when coupled with the regional weather and climate model COSMO-CLM.

Schubert, Sebastian; Grossman-Clarke, Susanne; Martilli, Alberto

2012-12-01

414

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

SciTech Connect

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: 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.

R.J. Maurer

1999-06-01

415

Lithologic descriptions and temperature profiles of five wells in the southwestern Valles caldera region, New Mexico  

SciTech Connect

The subsurface stratigraphy and temperature profiles of the southern and western Valles caldera region have been well constrained with the use of data from the VC-1, AET-4, WC 23-4, PC-1 and PC-2 wells. Data from these wells indicate that thermal gradients west of the caldera margin are between 110 and 140)degrees)C/km, with a maximum gradient occurring in the bottom of PC-1 equal to 240)degrees)C/km as a result of thermal fluid flow. Gradients within the caldera reach a maximum of 350)degrees)C/km, while the maximum thermal gradient measured southwest of the caldera in the thermal outflow plume is 140)degrees)C/km. The five wells exhibit high thermal gradients (>60)deghrees)C/km) resulting from high conductive heat flow associated with the Rio Grande rift and volcanism in the Valles caldera, as well as high convective heat flow associated with circulating geothermal fluids. Gamma logs run in four of the five wells appear to be of limited use for stratigraphic correlations in the caldera region. However, stratigraphic and temperature data from the five wells provide information about the structure and thermal regime of the southern and western Valles caldera region. 29 refs., 9 figs. 2 tabs.

Shevenell, L.; Goff, F.; Miles, D.; Waibel, A.; Swanberg, C.

1988-01-01

416

Water Temperatures in Select Nearshore Environments of the Colorado River in Grand Canyon, Arizona, During the Low Steady Summer Flow Experiment of 2000.  

National Technical Information Service (NTIS)

Water releases from Glen Canyon Dam, Arizona, are the primary determinant of streamflow, sediment transport, water quality, and aquatic and riparian habitat availability in the Colorado River downstream of the dam in Grand Canyon. The presence and operati...

C. R. Anderson, W. S. Vernieu

2013-01-01

417

Geomorphic process fingerprints in submarine canyons Daniel S. Brothers , Uri S. ten Brink, Brian D. Andrews, Jason D. Chaytor, David C. Twichell  

E-print Network

Geomorphic process fingerprints in submarine canyons Daniel S. Brothers , Uri S. ten Brink, Brian D fingerprint that is dependent on the catchment area of the canyon head. Catchment area, in turn, may

ten Brink, Uri S.

418

Bell Canyon Test (BCT) cement grout development report  

SciTech Connect

Development of the cement grout for the Bell Canyon Test was accomplished at the US Army Engineer Waterways Experiment Station (WES), Vicksburg, Mississippi. Initial development work centered on a saltwater grout with Class H cement, fly ash, and an expansive additive. Testing of the saltwater grout showed suitable properties except for the interface between anhydrite rock and grout in small core samples. Higher than expected permeability occurred at the interface because of space between the grout and the anhydrite; the space was produced as a result of allowing the specimens to dry. A change to freshwater grout and proper care to prevent the specimens from drying alleviated this condition. The BCT-1FF freshwater grout mixture was used in both the plug ONE and ONEX field grouting operations. Testing of the development grout mixtures was also done at Dowell, Pennsylvania State University, and Oak Ridge National Laboratory. Results of the testing and evaluation by the four laboratories are included in the report. Field batching, mixing, and placement of the grout at the plug locations for both plug ONE and ONEX were satisfactory with adequate quality control. The freshwater grout mixture maintained adequate flow characteristics for pumpability for 3 1/2 h during each of the two field operations. Physical property and expansivity data for the field samples through 90 days' age are in general agreement with laboratory development data. A large number of samples were obtained for inclusion in the long-term durability studies and the geochemical programs. The high-density, low water-cement ratio expansive grout (BCT-1FF) is considered to be an excellent candidate for plugging boreholes at most locations (except through halite sections).

Gulick, C.W. Jr.; Boa, J.A. Jr.; Buck, A.D.

1980-12-01

419

Novel observations on the massive Barkley Canyon hydrates  

NASA Astrophysics Data System (ADS)

We report on the early results of an August 2006 expedition to the massive exposed hydrates found at 850m depth in Barkley Canyon, off-shore Vancouver Island. We used the ROV Tiburon to explore, image, and sample the site, and also to carry out a series of novel experimental techniques and measurements in situ. We used the DORISS II laser Raman spectrometer for direct real time in situ measurement of hydrate composition and structure. The DORISS II system was equipped with highly modified pressure compensated optical fibers, resulting in far less signal loss than in earlier versions. This resulted in identification of gases including methane, ethane, propane, and isobutane in the Structure II hydrate simply by holding the probe head in the vehicle arm, pointing, and focusing the beam with a moveable internal stage. The site revealed white, easily cored, non-fluorescent hydrate underlying much harder yellow oil stained hydrate with significant fluorescence. Raman spectra were obtained of both hydrate types. A newly built small coring system was used to obtain specimens of well defined shape, which were inserted into a mesh chamber for time lapse video imaging to determine dissolution rates. Pressurized and non-pressurized cores were also obtained for cross- calibration in the on-shore laboratory using Raman, NMR, and XRD. A first attempt at an in situ CH4-CO2 hydrate conversion experiment was made by inserting buoyant cored specimens into a glass walled chamber, introducing ~ 2 liter liquid CO2, and placing the unit on a flat plate to seal the system and prevent large scale loss of dissolved CO2 to the surrounding ocean. We collaborated with MBARI's AUV mapping team, who obtained high resolution bathymetry, side scan, and sub-sea floor acoustic images of the site.

Brewer, P. G.; Peltzer, E. T.; Kirkwood, W. J.; Dunk, R. M.; Walz, P.; Hester, K.; Sloan, E. D.

2006-12-01

420

The eect of a submarine canyon on the river sediment dispersal and inner shelf sediment movements in  

E-print Network

-ping Submarine Canyon; bottom nepheloid layer; mud trap; grain-size distribution; EOF analysis; McLaren Model that coincides with the presence of high suspended sediment concentration (SSC) spots in the bottom nepheloid layer. Outside the submarine canyon on the shelf where the evidence of wave reworking is strong

Lin, Andrew Tien-Shun

421

Canyon Disposal Initiative - Numerical Modeling of Contaminant Transport from Grouted Residual Waste in the 221-U Facility (U Plant)  

Microsoft Academic Search

This letter report documents initial numerical analyses conducted by PNNL to provide support for a feasibility study on decommissioning of the canyon buildings at Hanford. The 221-U facility is the first of the major canyon buildings to be decommissioned. The specific objective of this modeling effort was to provide estimates of potential rates of migration of residual contaminants out of

Mark L. Rockhold; Mark D. White; Eugene J. Freeman

2004-01-01

422

Distribution of DDT and other persistent organic contaminants in Canyons and on the continental shelf off the central California coast  

Microsoft Academic Search

Sediment samples were collected to delineate the distribution of contaminants along the central California coast. Sampling included a variety of Canyons and shelf\\/slope areas to evaluate contaminant transport patterns and potential delivery to Canyons and the continental slope to a depth of 1200m. Sediments were collected and analyzed for organic contaminants using standard techniques of the NOAA National Status and

S. Ian Hartwell

2008-01-01

423

Assessment and prediction of benzene concentrations in a street canyon using artificial neural networks and deterministic models  

Microsoft Academic Search

The work deals with the comparison of two models: (i) an artificial neural network (ANN) and (ii) a semi empirical deterministic model (DET), used to simulate benzene concentrations in a street canyon. Furthermore, the response of models to ‘what if scenarios’ was also examined.The ANN was based on a training procedure using measurements collected in a specific street canyon (benzene

Spyros P. Karakitsios; Costas L. Papaloukas; Pavlos A. Kassomenos; Georgios A. Pilidis

2006-01-01

424

Late Quaternary Spring-Fed Deposits of the Grand Canyon and Their Implication for Deep Lava-Dammed Lakes  

Microsoft Academic Search

One of the most intriguing episodes in the Quaternary evolution of the Grand Canyon of the Colorado River, Arizona, was the development of vast lakes that are thought to have backed up behind lava erupted into the gorge. Stratigraphic evidence for these deep lava-dammed lakes is expectedly sparse. Possible lacustrine deposits at six areas in the eastern canyon yielded no

Darrell S. Kaufman; Gary O'Brien; Jim I. Mead; Jordon Bright; Paul Umhoefer

2002-01-01

425

Distribution and Abundance of Native and Non-native Fishes of the Colorado River Ecosystem in Grand Canyon, Arizona  

Microsoft Academic Search

The Colorado River ecosystem in Grand Canyon is strongly impacted by operation of Glen Canyon Dam. Fluctuating releases of cold, hypolimnetic water from Lake Powell (~8ºC) for peak hydroelectric power generation has had a profound impact on the formerly warm, silty Colorado River. Clear, cold stenothermal conditions preclude successful reproduction and recruitment of most native fishes in the mainstem and

OWEN T. GORMAN; ROBERT G. BRAMBLETT; ROBERTA M. HERVIN; DAVID R. VANHAVERBEKE; DENNIS M. STONE

426

IMPLICATIONS OF THE DISCOVERY OF RANA YAVAPAIENSIS IN THE WESTERN GRAND CANYON TO THE CONSERVATION STRATEGY FOR RANA ONCA  

EPA Science Inventory

The minimum historical range of the relict leopard frog, Rana onca, comprises the drainages of the Virgin and Colorado rivers from the vicinity ofHurricane, Utah, to Black Canyon below Lake Mead, in Nevada and Arizona. Extant populations are known near only the Black Canyon and O...

427

Diatom biostratigraphy from dolomites in Monterey Formation, Rodeo Canyon to Point Pedernales, southwestern Santa Barbara County, California  

Microsoft Academic Search

Eight-six samples were collected from three stratigraphic sections in southwestern Santa Barbara County, California: Rodeo Canyon, Lyons Head, and Point Pedernales. In this area, the Monterey Formation is exposed in prominent cliffs along the coast from Rodeo Canyon on the south, to Lyons Head and Point Pedernales on the west. Because most of the opal-A in the Monterey diatomaceous shale

W. W. Wornardt

1986-01-01

428

Frequency and initiation of debris flows in Grand Canyon, Arizona Peter G. Griffiths and Robert H. Webb  

E-print Network

triggers failures in colluvium by a process termed ``the fire hose effect.'' Debris flows originate fromFrequency and initiation of debris flows in Grand Canyon, Arizona Peter G. Griffiths and Robert H 2004. [1] Debris flows from 740 tributaries transport sediment into the Colorado River in Grand Canyon

429

Nonnative Fish Control in the Colorado River in Grand Canyon, Arizona: An Effective Program or Serendipitous Timing?  

Microsoft Academic Search

The federally endangered humpback chub Gila cypha in the Colorado River within Grand Canyon is currently the focus of a multiyear program of ecosystem-level experimentation designed to improve native fish survival and promote population recovery as part of the Glen Canyon Dam Adaptive Management Program. A key element of this experiment was a 4-year effort to remove nonnative fishes from

Lewis G. Coggins Jr; Michael D. Yard; William E. Pine III

2011-01-01

430

Morphotectonic, seismic characteristics and development of the Off Pearl River Mouth Canyon, North South China Sea margin  

Microsoft Academic Search

The north continental margin of the South China Sea is the main depo-centre for sediment supply from South China via Pearl River. The continental slope is disserted by numerous canyons, each of which is fed by several tributaries. These canyons commonly stop at the shelf-break or slightly upward from it. The unique and notable exception is the Off Pearl River

W. Ding

2009-01-01

431

SEROCONVERSION RATES TO JAMESTOWN CANYON VIRUS AMONG SIX POPULATIONS OF WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) IN INDIANA  

Microsoft Academic Search

The annual seroconversion of fawns, yearlings, and adult white-tailed deer (Odocoi- leus virginianus) to Jamestown Canyon virus (California group) was followed at six Indiana sites from 1981 through 1984. In all, sera from 1,642 deer (515 fawns, 618 yearlings, and 509 adults) were tested for neutralizing antibody to three California serogroup viruses: Jamestown Canyon, La Crosse, and trivittatus. Virtually all

Robert D. Boromisa; Paul R. Grimstad

432

Debris flows in Grand Canyon National Park, Arizona: magnitude, frequency and effects on the Colorado River  

USGS Publications Warehouse

Debris flows are recurrent sediment-transport processes in 525 tributaries of the Colorado River in Grand Canyon. Arizona. Initiated by slope failures in bedrock and (or) colluvium during intense rainfall, Grand Canyon debris flows are high-magnitude, short-duration floods. Debris flows in these tributaries transport very large boulders into the river where they accumulate on debris fans and form rapids. The frequency of debris flows range from less than 1 per century to 10 or more per century in these tributaries. Before regulation by Glen Canyon Dam in 1963, high-magnitude floods on the Colorado River reworked debris fans by eroding all particles except large boulders. Because flow regulation has substantially decreased the river's competence, debris flows occurring after 1963 have increased accumulation of finer-grained sediments on debris fans and in rapids.

Melis, Theodre, S.; Webb, Robert, H.

1993-01-01

433

Vegetation and substrate properties of aeolian dune fields in the Colorado River corridor, Grand Canyon, Arizona  

USGS Publications Warehouse

This report summarizes vegetation and substrate properties of aeolian landscapes in the Colorado River corridor through Grand Canyon, Arizona, in Grand Canyon National Park. Characterizing these parameters provides a basis from which to assess future changes in this ecosystem, including the spread of nonnative plant species. Differences are apparent between aeolian dune fields that are downwind of where modern controlled flooding deposits new sandbars (modern-fluvial-sourced dune fields) and those that have received little or no new windblown sand since river regulation began in the 1960s (relict-fluvial-sourced dune fields). The most substantial difference between modern- and relict-fluvial-sourced aeolian dune fields is the greater abundance of biologic soil crust in relict dune fields. These findings can be used with similar investigations in other geomorphic settings in Grand Canyon and elsewhere in the Colorado River corridor to evaluate the health of the Colorado River ecosystem over time.

Draut, Amy E.

2011-01-01

434

A Miocene river in northern Arizona and its implications for the Colorado River and Grand Canyon  

USGS Publications Warehouse

The southwesterly course of the pre–late Miocene Crooked Ridge River can be traced continuously for 48 km and discontinuously for 91 km in northern Arizona. It is visible today in inverted relief. Pebbles in the river gravel came from at least as far northeast as the San Juan Mountains. The river valley was carved out of easily eroded Jurassic and Cretaceous rocks, whose debris overloaded the river with abundant detritus, possibly steepening the gradient. After the river became inactive, the regional drainage network was rearranged twice, and the Four Corners region was lowered by erosion 1–2 km. The river provides constraints on the history of the Colorado River and Grand Canyon; its continuation into lakes in Arizona or Utah is unlikely, as is integration of the Colorado River through Grand Canyon by lake spillover. The downstream course of the river was probably across the Kaibab Arch in a valley roughly coincident with the present eastern Grand Canyon.

Lucchitta, I.; Holm, R. F.; Lucchitta, B. K.

2011-01-01

435

Stratigraphic framework and petroleum potential of Northeastern Baltimore Canyon Trough, Mid-Atlantic Outer Continental Shelf  

SciTech Connect

Geologic data from 29 wells in the Baltimore Canyon Trough were released to the public as of 1982, and provide sufficient information for establishing Upper Jurassic through Cenozoic rock-stratigraphic units. The oldest rocks penetrated by exploratory wells are of Late Jurassic age and are correlative to the Scotian Shelf Mohawk, Mic Mac, and Abenaki Formations. The Mohawk(.) sandstone and Mic Mac shale equivalents in the Baltimore Canyon Trough represent lower delta plain to predominantly prodelta environments, and the Abenaki-equivalent limestone represents a shelfmargin carbonate buildup. A destructional phase of the delta is represented by the Naskapi equivalents a calcareous shale. Stratigraphic traps may be present in the Baltimore Canyon Trough Upper Jurassic and Lower Cretaceous deltaic sandstones and shelf-margin carbonates. The deltaic units contain channel and distributary-mouth-bar sandstones, which may be potential reservoirs. The Abenaki stratigraphic-reef trend provides another potential target.

Libby-French, J.

1984-01-01