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1

Valles Marineris  

NASA Technical Reports Server (NTRS)

A color image of Valles Marineris, the great canyon of Mars; north toward top. The scene shows the entire canyon system, over 3,000 km long and averaging 8 km deep, extending from Noctis Labyrinthus, the arcuate system of graben to the west, to the chaotic terrain to the east. This image is a composite of Viking medium-resolution images in black and white and low-resolution images in color; Mercator projection. The image extends from latitude 0 degrees to 20 degrees S. and from longitude 45 degrees to 102.5 degrees. The connected chasma or valleys of Valles Marineris may have formed from a combination of erosional collapse and structural activity. Layers of material in the eastern canyons might consist of carbonates deposited in ancient lakes. Huge ancient river channels began from Valles Marineris and from adjacent canyons and ran north. Many of the channels flowed north into Chryse Basin, which contains the site of the Viking 1 Lander and the future site of the Mars Pathfinder Lander.

1997-01-01

2

New insights on the runout of large landslides in the Valles-Marineris canyons, Mars  

E-print Network

New insights on the runout of large landslides in the Valles-Marineris canyons, Mars E. Lajeunesse experiments demonstrates that runouts and deposits heights of Valles- Marineris (VM) landslides can be scaled). This results suggests both that any interstitial fluid played a negligible part in the VM landslides dynamics

Lajeunesse, Eric

3

Valles Marineris Hemisphere  

NASA Technical Reports Server (NTRS)

Mosaic composed of 102 Viking Orbiter images of Mars, covering nearly a full hemisphere of the planet (approximate latitude -55 to 60 degrees, longitude 30 to 130 degrees). The mosaic is in a point-perspective projection with a scale of about 1 km/pixel. The color variations have been enhanced by a factor of about two, and the large-scale brightness variations (mostly due to sun-angle variations) have been normalized by large-scale filtering. The center of the scene shows the entire Valles Marineris canyon system, over 3,000 km long and up to 8 km deep, extending from Noctis Labyrinthus, the arcuate system of graben to the west, to the chaotic terrain to the east. Bright white layers of material in the eastern canyons may consist of carbonates deposited in ancient lakes. Huge ancient river channels begin from the chaotic terrain and from north-central canyons and run north. Many of the channels flowed into a basin called Acidalia Planitia, which is the dark area in the extreme north of this picture. The Viking 1 landing site (Mutch Memorial Station) is located in Chryse Planitia, south of Acidalia Planitia. The three Tharsis volcanoes (dark red spots), each about 25 km high, are visible to the west. The large crater with two prominent rings located at the bottom of this image is named Lowell, after the Flagstaff astronomer. The images were acquired by Viking Orbiter 1 in 1980 during early northern summer on Mars (Ls = 70 degrees); the atmosphere was relatively dust-free. A variety of clouds appear as bright blue streaks and hazes, and probably consist of water ice. Long, linear clouds north of central Valles Marineris appear to emanate from impact craters.

1992-01-01

4

Valles Marineris and Chryse Outflow Channels  

NASA Technical Reports Server (NTRS)

A color image of Valles Marineris, the great canyon and the south Chryse basin-Valles Marineris outflow channels of Mars; north toward top. The scene shows the entire Valles Marineris canyon system, over 3,000 km long and averaging 8 km deep, extending from Noctis Labyrinthus, the arcuate system of graben to the west, to the chaotic terrain to the east and related outflow canyons that drain toward the Chryse basin. Eos and Capri Chasmata (south to north) are two canyons connected to Valles Marineris. Ganges Chasma lies directly north. The chaos in the southeast part of the image gives rise to several outflow channels, Shalbatana, Simud, Tiu, and Ares Valles (left to right), that drained north into the Chryse basin. The mouth of Ares Valles is the site of the Mars Pathfinder lander.

This image is a composite of Viking medium-resolution images in black and white and low-resolution images in color; Mercator projection. The image roughly extends from latitude 20 degrees S. to 20 degrees N. and from longitude 15 degrees to 102.5 degrees.

The connected chasma or valleys of Valles Marineris may have formed from a combination of erosional collapse and structural activity. Layers of material in the eastern canyons might consist of carbonates deposited in ancient lakes, eolian deposits, or volcanic materials. Huge ancient river channels began from Valles Marineris and from adjacent canyons and ran north. Many of the channels flowed north into Chryse Basin.

The south Chryse outflow channels are cut an average of 1 km into the cratered highland terrain. This terrain is about 9 km above datum near Valles Marineris and steadily decreases in elevation to 1 km below datum in the Chryse basin. Shalbatana is relatively narrow (10 km wide) but can reach 3 km in depth. The channel begins at a 2- to 3-km-deep circular depression within a large impact crater, whose floor is partly covered by chaotic material, and ends in Simud Valles. Tiu and Simud Valles consist of a complex of connected channel floors and chaotic terrain and extend as far south as and connect to eastern Valles Marineris. Ares Vallis originates from discontinuous patches of chaotic terrain within large craters. In the Chryse basin the Ares channel forks; one branch continues northwest into central Chryse Planitia and the other extends north into eastern Chryse Planitia.

1997-01-01

5

New insights on the runout of large landslides in the Valles-Marineris canyons, Mars  

NASA Astrophysics Data System (ADS)

Analogy with lab-scale dry granular flow experiments demonstrates that runouts and deposits heights of Valles-Marineris (VM) landslides can be scaled on a curve varying primarily with the initial aspect ratio of the mobilized rock mass (before slope failure). This results suggests both that any interstitial fluid played a negligible part in the VM landslides dynamics and that mobility is not an appropriate tool to characterize their dynamics.

Lajeunesse, E.; Quantin, C.; Allemand, P.; Delacourt, C.

2006-02-01

6

Valles Marineris cloud trails  

NASA Astrophysics Data System (ADS)

Distinctive cloud trails are identified in Mars Reconnaissance Orbiter Mars Color Imager (MARCI) images over specific locations associated with Valles Marineris and Noctis Labyrinthus and at perihelion solar longitudes (LS = 230°-260°). High-contrast surface shadows are well defined, as cast from their eastern margins, supporting altitude and optical depth determinations. These relatively high altitude clouds (40-50 km) exhibit narrow latitudinal widths (25-75 km) in comparison to extended longitudinal dimensions (400-1000 km). MARCI multispectral imaging of cloud surface shadows in five wavelength channels (260, 320, 437, 546, and 653 nm) yields the wavelength dependence of cloud extinction optical depth, revealing a range of small cloud particle sizes (reff = 0.2-0.5 ?m) and moderate cloud optical depths (0.03-0.10 visible and 0.1-0.2 ultraviolet). Local time and temporal sampling characteristics of MARCI cloud images indicate that these clouds develop very rapidly in afternoon hours (1300-1500 LT), reach their full longitudinal extents within <2 h time scales, and often reoccur on successive afternoons. Mars Global Surveyor Mars Orbital Camera imaging in previous Mars years indicates these clouds are annually repeating. These observed characteristics suggest a cloud formation mechanism that is specific to ˜50 km horizontal and vertical scales, transports water vapor and dust upward from lower levels, exists during the afternoon, and is likely associated with the mesoscale atmospheric circulations induced by the near-equatorial canyons of Mars. Cloud particles formed in such updrafts would then be rapidly transported westward in the strong retrograde zonal circulation of the subsolar middle atmosphere in this season.

Clancy, R. Todd; Wolff, Michael J.; Cantor, Bruce A.; Malin, Michael C.; Michaels, Timothy I.

2009-11-01

7

Lakes in Valles Marineris  

NASA Astrophysics Data System (ADS)

The paper reviews the evolution of hypotheses of lakes in Valles Marineris through observations made from the time of Mariner and continuing through the Viking, MGS, MO, MEx, and MRO missions. Several pertinent findings from these missions are addressed, including: The morphology and composition of the interior layered deposits (ILD); the question whether ILD are deposited inside the troughs or exhumed from the walls; the possible existence of ancestral basins; the derivation of water; arguments for an origin as aqueous, eolian, or pyroclastic sediments, or sub/ice volcanoes; origin of inclined layers, mounds and moats; and age relations of features within and peripheral to the troughs. A possible scenario begins with the collapse of ice-charged ground into ancestral basins along structural planes of weakness due to Tharsis stresses, about 3.5 Ga ago. The basins rapidly filled with water from ground ice, subterranean aquifers, or nearby valley networks. The water spilled out of the peripheral troughs and flowed across high plateaus into early outflow channels. The ancestral basins then filled with sediments derived from valley networks or from trapped eolian or pyroclastic deposits. Alternatively, volcanoes rose under the water or ice to form tuyas. The water was highly acidic, and sediments may have been deposited directly as evaporites or were later altered to evaporites by the brines or by hydrothermal activity. Percolating fluids produced iron oxide concretions. Similar alteration would have affected the putative volcanoes. Most of the ILD were emplaced early in the troughs' history. Shortly thereafter, more water erupted from the peripheral troughs and formed additional chaos and outflow channels. The ancestral basins were breached by erosion and tectonism, and the through-going Coprates/Ius graben system developed. Major lakes within the Valles Marineris dried up and vigorous wind erosion reduced the friable, evaporite-rich sediments to isolated mounds. Simultaneously, the iron oxide concretions weat hered out to form lag deposits mostly at the base of scarps. During that time, some of the ILD may have become tilted by structural deformation. Alternatively, inclined beds on the mounds may have come from draping by volcanic ash or eolian deposits, or by gravity sliding on the steep, evaporite-charged flanks of the mounds. Inclined layers could be readily explained if the ILD were tuyas. Landslides fell into the newly created voids and occasional sliding persisted throughout most of the troughs' history. Minor volcanic activity continued and may have spewed mafic ash onto the eroded ILD-mound surfaces and onto the trough floors. Eventually, only wind persisted, producing yardangs on the ILD and reworking ash, trapped eolian sediments, and debris eroded from the ILD.

Lucchitta, Baerbel K.

2010-10-01

8

Mars: Volcanism in the Valles Marineris overlooked  

NASA Technical Reports Server (NTRS)

Do volcanic rocks exist in the Valles Marineris. This question is pertinent because the Valles Marineris are gigantic grabens, rivaling rift valleys on earth in size and depth. The Valles Marineris were interpreted as extensional tectonic structures, perhaps incipient rifts. On earth, rift valleys commonly contain volcanic deposits. On Mars, deposits inside the Valles Marineris grabens do not have the morphologic signature of such easily identified volcanic features as shield volcanoes or lava flows. Therefore, many researchers have not recognized the deposits inside the Valles Marineris as volcanic. Is Mars, then, different from earth in having formed riftlike grabens unaccompanied by volcanism. Overall, results from the study suggest that volcanism was present in the Valles Marineris; the volcanism was explosive in places; some volcanism was more felsic than that generally assumed elsewhere; and the younger sequence of interior beds was emplaced so late in Martian history that the planet may be considered to be still volcanically active.

Lucchitta, B. K.

1988-01-01

9

Valles Marineris - with 3D  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

The top half of this THEMIS visible image shows interior layered deposits that have long been recognized in Valles Marineris. Upon close examination, the layers appear to be eroding differently, indicating different levels of competency. This, in turn, may be interpreted to indicate different materials, and/or depositional processes. At the bottom of the image, materials eroded from the walls of the canyon form dunes and other aeolian bedforms.

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.

Image information: VIS instrument. Latitude -6.5, Longitude 287.3 East (72.7 West). 19 meter/pixel resolution.

2003-01-01

10

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 22 March 2010; published 23 April 2010. [1] Multiple occurrences of "wall dunes" are found several kilometers above the Valles Marineris canyon floor. Dune slip face orientation and bed form morphologies

Perfect, Ed

11

Erosional landforms on the layered terrains in Valles Marineris  

NASA Technical Reports Server (NTRS)

Many investigators have proposed potential lakes in Valles Marineris based on the relationship with outflow channels, and a proposed lacustrine origin of layered deposits. We have investigated the erosional style of the layered terrains and evaluated their potential origins as sedimentation in and erosional modification by these lakes. The erosional features that will be discussed are distributed in the central canyon area and classified into terraces and layered depressions. Many terraces can be explained by coastal erosion in lakes as well as by eolian erosion. The lack of terraces on the canyon walls is probably due to more recent sapping and mass wasting of materials with different mechanical response to erosion than the layered terrains. Catastrophic water discharges in Valles Marineris as hypothesized by an ocean model may have been the source of the lakes and the eventual catastrophic release of water from the canyons.

Komatsu, G.; Strom, R. G.; Gulick, V. C.; Parker, T. J.

1992-01-01

12

Extension and Strain Across Valles Marineris  

NASA Astrophysics Data System (ADS)

Extension and strain are calculated for six traverses across the Martian Valles Marineris troughs. Extension accommodated by the large trough normal faults varies systematically along the length of the trough system, increasing from 5-10 km near the eastern and westem termini to a maximum value of 20-30 km near the center, assuming 60 degree fault dip angles and +1 km in trough relief. The spatial gradient in extension exceeds reasonable uncertainties in both topography and fault dip, demonstrating an inhomogeneous deformation field along strike, similar to other well documented examples of normal faults and grabens on Earth. Strain also varies with position, typically between 5% and 20%. Smaller values of strain reported for the Valles Marineris region, <2%, that include large expanses of unextended terrain represent spatial averages that may underestimate the magnitude of strain at the troughs.

Schultz, R. A.

1996-03-01

13

Amounts of crustal stretching in Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

Terrestrial grabens and continental rifts are compared with the Valles Marineris system, in order to define the mechanisms which could be responsible for its geometry and formation. Simple shear/pure shear mechanisms, symmetric/asymmetric grabens and faults, high/low dip angles, block tilting/no block tilting, shouldering or not, lithospheric layering, and amount of sedimentation on chasma floors are discussed. Amounts of stretching on several transverse topographic profiles are then calculated, assuming either block tilting or no block tilting. On each profile initial dip angles ranging from 40 to 90, and sediment thicknesses ranging from 0 to 3 km are considered, as well as symmetric and asymmetric border fault dips. The case of Ius Chasma, the southwestern trough of the Valles Marineris system, is first considered, then the entire graben system. Considering a constant 660 km profile length, stretching increases eastward in Ius Chasma from the Noctis Labyrinthus boundary (stretching factor ? = 1.01-1.02, assuming initial 60 dipping faults) to the middle part of this trough (? = 1.04-1.06). Then Ius Chasma stretching decreases, but is partly taken over by stretching in Candor and Ophir chasmata. Stretching decreases from the eastern part of Melas Chasma (? = 1.05-1.06) to almost the eastern end of Coprates Chasma (? = 1.01). Then stretching increases again eastward (? = 1.02-1.04) at the longitude Coprates Chasma splits around a horst and Gangis Chasma opens northward. A striking feature is that a low peak of extension in the centre of the Valles Marineris troughs is observed (? = 1.03-1.04). The low stretching peak in the central part of Valles Marineris may originate from the existence of buried structures in the grabens, and/or along-strike variations in sediment thickness. According to the profiles and to the hypotheses, some 9-26 km of additional normal movements along faults with dip angles equivalent to the dip angles of the walls would be expected within the central Valles Marineris grabens to get constant stretching from Ius to Coprates chasmata. The amount of this lacking offset may be partly explained by a few km subsidence of Ophir Planum, and the shallow inter-chasmata grabens. Part of the remaining lacking normal movements are best explained by buried structures (possibly shallow horst and graben alternances or other structures) in the major canyons: Melas, Candor, and/or Ophir chasmata - probably mainly in Melas Chasma. Alternatively, along-strike variations of sediment thickness (about 3 km) without taking such buried structures into account, can explain the results as well. Observation of images shows up that the most realistic structural model of Valles Marineris should probably consider both variations of sediment thicknesses and existence of buried structures. Models for the origin of Valles Marineris stretching are discussed. The role of passive rifting in crust weakened by hot spot is emphasized, although extensional stresses due to the Tharsis load should have also contributed to stretching.

Mège, Daniel; Masson, Philippe

1996-08-01

14

Planetary and Space Science 52 (2004) 10111022 Morphology and geometry of Valles Marineris landslides  

E-print Network

landslides C. Quantin�, P. Allemand, C. Delacourt Universite´ Claude Bernard Lyon-1 & ENS Lyon, Laboratoire, France Abstract The walls of the Valles Marineris canyons are affected by about 45 landslides. The study of these landslides provides a test of the hypothesis of processes having affected Martian wallslopes after

Delacourt, Christophe

15

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

16

Landslides in Valles Marineris, Mars  

NASA Technical Reports Server (NTRS)

The morphology of the landslides in the Martian equatorial troughs, the geologic structure of the troughs, the time of emplacement, the similarity to terrestrial landslides, and the origin and mechanism of transport are analyzed. About 35 large landslides well-resolved on Viking images were examined, and it is found that the major landslides cover 31,000 sq km of the trough floors, and individual slides range in area from 40 to 7000 sq km. The morphologic variations of the landslides can be attributed mainly to their degree of confinement on trough floors. Many prominent landslides appear to be of similar age and were emplaced after a major faulting that dropped the trough floors. Most sliding occurred after the created scarps were dissected into spurs, gullies, and tributary canyons. Emplacement of the landslides approximately coincided with a late episode of major eruptive activity of the Tharsis volcanoes, and it is suggested that the slides may have originated as gigantic mudflows with slump blocks at their heads. The large size of many landslides is due to the fault scarps as high as 7 km on which they formed in the absence of vigorous fluvial erosion. The landslides suggest that Mars is earthlike in some respects, which may be important for further evaluations.

Lucchitta, B. K.

1979-01-01

17

Origin an evolution of the Valles Marineris region of the Mars  

NASA Astrophysics Data System (ADS)

An attempt is made to relate the tectonic interpretation of the wide canyon system of Valles Marineris on Mars to its geomorphic evolution. Tectonic activity due to crustal extension related to the Tharsis-Syria rise (regional doming or lithospheric response to volcanic loading) appears to be the fundamental influence on the canyon formation and evolution. Tectonic activity contributed to the deepening of the canyon system and competed with erosional and depositional processes that caused the canyon to broaden and fill in. Mass wasting, downfaulting, seepage of liquid water and sublimation of ground ice are processes considered.

Masson, Ph.

18

Water and ice on Mars: Evidence from Valles Marineris  

NASA Technical Reports Server (NTRS)

An important contribution to the volatile history of Mars comes from a detailed study of Valles Marineris, where excellent stereoimages and a three-dimensional view of the upper Martian crust permit unusual insights. The evidence that ground water and ice existed until relatively recently or still exist in the equatorial area comes from observations of landslides, wall rock, and dark volcanic vents. Valles Marineris landslides are different in efficiency from large catastrophic landslides on Earth. One explanation for the difference might be that the Martian slides are lubricated by water. A comparison of landslide speeds also suggests that the Martian slides contain water. That Valles Marineris wall rock contained water or ice is further suggested by its difference from the interior layered deposits. Faults and fault zones in Valles Marineris also shed light on the problem of water content in the walls. Because the main evidence for water and ice in the wall rock comes from landslides, their time of emplacement is important. The landslides in Valles Marineris date from the time of late eruptions of the Tharsis volcanoes and thus were emplaced after the major activity of Martian outflow channels. None of the observations conclusively demonstrate that water or ice existed in the wall rock of Valles Marineris, but altogether the evidence is highly suggestive.

Lucchitta, B. K.

1987-01-01

19

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

20

Valles Marineris: a past glaciated valley landsystem along the Martian equator  

NASA Astrophysics Data System (ADS)

Various ice-related features occurring on the floor of Valles Marineris suggest that this canyon system that stretches along the Martian equator has experienced a period of past glacial activity. Three regions of Valles Marineris were investigated, Coprates Chasma, Candor Chasma, and Ius Chasma. Geomorphological observations are based on images and altimetry analysis by using the Context Camera (CTX), the High Resolution Imaging Science Experiment (HiRISE) and MOLA PEDR single tracks. The study reveals some features reminiscent of a past glaciated valley landsystem in these regions. A line running along the base of valley wallslopes and associated with spur and gully morphology can be interpreted as a periglacial trimline. Other landforms on the floor of Candor Chasma can be interpreted as stagnant ice features such as polygonal terrains, chaotic terrains which look similar to terrestrial ablation moraines with kettle holes. Ancient ice probably also persists now in Candor Chasma in the form of a debris covered glacier with a surface elevation that is consistent with that of the trimline. In Coprates Chasma, hanging valleys provide additional evidence for the former existence of an extensive glacial filling of Valles Marineris. Terraced mounds resting on the floor of Coprates Chasma and around basement domes can be interpreted as stagnant remnants of stratified ice. Altogether, these landforms define a full glacial landsystem consistent with global climate models that predict glaciations in Valles Marineris during the Late Amazonian.

Gourronc, M.; Bourgeois, O.; Mège, D.; Bultel, B.; Pochat, S.

2012-04-01

21

Water and ice on Mars: Evidence from Valles Marineris  

NASA Technical Reports Server (NTRS)

An important contribution to the volatile history of Mars comes from a study of Valles Marineris, where stereoimages and a 3-D view of the upper Martian crust permit unusual insights. The evidence that ground water and ice existed until relatively recently or still exist in the equatorial area comes from observations of landslides, wall rock, and dark volcanic vents. Valles Marineris landslides are different in efficiency from large catastrophic landslides on Earth. One explanation for the difference might be that the Martian slides are lubricated by water. A comparison of landslide speeds also suggests that the Martian slides contain water. That Valles Marineris wall rock contained water or ice is further suggested by its difference from the interior layered deposits. Faults and fault zones in Valles Marineris also shed light on the problem of water content in the walls. Because the main evidence for water and ice in the wall rock comes from slides, their time of emplacement is important. The slides in Valles Marineris date from the time of late eruptions of the Tharsis volcanoes and thus were emplaced after the major activity of Martian outflow channels.

Lucchitta, B. K.

1987-01-01

22

Tharsis Volcanoes and Valles Marineris, Mars  

NASA Technical Reports Server (NTRS)

It is northern summer on Mars and clouds are very common over the famous Tharsis volcanoes during the afternoon. At the far left, a white patchy cloud denotes the location of Olympus Mons. Ascraeus Mons is under the brightest cloud toward the center left, but the volcanoes Pavonis Mons and Arsia Mons (toward lower left below Ascraeus Mons) have much less cloud cover. The patch of clouds toward the upper left mark the location of the Alba Patera volcano. The Valles Marineris trough system--so long that it would stretch across North America--is seen in the lower third of this picture. This is a color composite of 9 red and 9 blue image strips taken by the Mars Global Surveyor Mars Orbiter Camera on 9 successive orbits from pole-to-pole during the calibration phase of the mission in March 1999. The color is computer-enhanced and is not shown as it would actually appear to the human eye.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1999-01-01

23

Slope stability analysis of Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

Valles Marineris (VM) in the equatorial area of Mars exhibits several gravitational failures which resulted in a series of large landslides up to several hundred cubic kilometers in volume. Questions arise as to forces at play and rock strength in the stability of the walls of VM. In this work we address the stability analysis of the walls of VM by considering the strength of the materials of the chasma walls and the causes of landslides. Using finite element calculations and the limit analysis upper bound method, we explore the range of cohesion and friction angle values associated to realistic failure geometries, and compare predictions with the classical Culmann's wedge model. Our analysis is based both on synthetic, simplified slope profiles and also on the real shape of the walls of VM taken from the MOLA topographic data. Validation of the calibrated cohesion and friction angle values is performed by comparing the computed unstable cross sectional areas with the observed pre- and post-failure profiles and estimated failure surface geometry. This offers a link between rock mass properties, slope geometry and volume of the observed failure. Pseudo-static seismic analyses generated another set of dimensionless charts. Our pseudo-static analyses show that low seismicity events induced by meteoroids impacts compatible with the size of craters could be a cause for some of the observed landslides if poor rock properties for VM is assumed.

Vittorio De Blasio, Fabio; Battista Crosta, Giovanni; Castellanza, Riccardo; Utili, Stefano

2013-04-01

24

Mars: New evidence for origin of some Valles Marineris layered deposits  

NASA Technical Reports Server (NTRS)

The discovery of layered deposits in the walls of a deep trough in Lunae Planum has implications for the origin of similar-appearing deposits in some canyons of Valles Marineris. Although layering is visible in the competent, cliff-forming upper walls of the canyons, the dissimilarity in appearance between canyon walls and soft rounded hills of layered deposits on canyon floors, as well as their contrasting patterns of erosion, has been considered strong evidence that their modes of origin were different. Most workers agree that the wall rocks are volcanic flows derived from fissure vents and other volcanic sources in the region. However, several hypotheses have been advanced to account for the softer-appearing stratified floor deposits. Chief among them is the proposal that the floor deposits are waterlaid sediments that accumulated in large lakes within the canyons and include materials eroded from canyon walls, eolian deposits, and subaqueous volcanic eruptives.

Scott, David H.

1993-01-01

25

Geomorphological studies on western Valles Marineris, Mars - landforms and processes  

NASA Astrophysics Data System (ADS)

Context Camera (CTX) images obtained by the Mars Reconnaissance Orbiter (MRO) covered ~85% of the Martian surface to February 2013 [1], including almost 100% coverage of the Valles Marineris trough system. The images of resolution 6 m/pixel play an important role as a background for detailed landform mapping of Mars. We present: (i) a detailed geomorphologic mapping procedure of western Valles Marineris based on USGS ISIS processing, ArcGIS mapping, and incorporation of additional data sets, (ii) observations of chasma floor and wall features.

D?bniak, K.; Mège, D.; Massé, M.

2014-04-01

26

Origin and evolution of the layered deposits in the Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

Four hypotheses are discussed concerning the origin of the layered deposits in the Martian Valles Marineris, whose individual thicknesses range from about 70 to 300 m. The hypothesized processes are: (1) aeolian deposition; (2) deposition of remnants of the material constituting the canyon walls; (3) deposition of volcanic eruptions; and (4) deposition in standing bodies of water. The last process is chosen as most consistent with the rhythm and lateral continuity of the layers, as well as their great thickness and stratigraphic relationship with other units in the canyons. Attention is given to ways in which the sediments could have entered an ice-covered lake; several geologically feasible mechanisms are identified.

Nedell, S. S.; Squyres, S. W.; Andersen, D. W.

1987-06-01

27

UNCORRECTEDPROOF 2 Valles Marineris landslides: Evidence for a  

E-print Network

controversies in Martian geology surround the role of active tectonics and a wetter climate early in Mars 23 Keywords: Mars; landslides; strength limit; climate; tectonics 24 25 1. Introduction 26 Large necessitating active tectonics, under either wet or dry conditions. We analyze Valles Marineris landslides 14

Montgomery, David R.

28

Morphology, evolution and tectonics of Valles Marineris wallslopes (Mars)  

Microsoft Academic Search

Hillslopes up to 11 km in height can be found along the walls of the Valles Marineris troughs. The widest and deepest troughs are grabens, in which tectonics probably exerted the primary control on the wall morphology. Geographical variations in the wall morphology and profiles show that they result from complex, persistent tectonic influences, and that significant changes in erosional

Jean-Pierre Peulvast; Daniel Mège; Jan Chiciak; François Costard; Philippe L. Masson

2001-01-01

29

New models for the origin of Valles Marineris closed depressions  

SciTech Connect

Current models for the formation of the abundant large closed depressions of Valles Marineris have serious shortcomings. Purely tectonic mechanisms are inconsistent with the morphology of many depressions, and removal of large quantities of ground ice from the canyon walls is inconsistent with the observed strength of the walls. Accordingly, the authors offer some alternatives. One possibility involves decay of ice-rich bodies occupying partially sediment-choked ancient graben that predated the overlying cratered and ridged plains. Other possibilities involve the removal of massive equatorial carbonate deposits storing much of the planet's CO{sub 2} inventory, generated during greenhouse conditions on early Mars. Solution by carbonic acid derived from the atmosphere (analogous to terrestrial karst) requires extensive recycling of the available water supply. Solution by various groundwater acids, possibly derived from the Tharsis magmas, requires less water, especially if only the smaller closed depressions are due to carbonate decay. Alternatively, volume loss due to decarbonation of carbonate during early high heat flow or a later Tharsis-related heat pulse can produce extensive collapse, especially if the carbonates have high silica content.

Spencer, J.R.; Fanale, F.P. (Univ. of Hawaii, Honolulu (USA))

1990-08-30

30

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

31

Young volcanic deposits in the Valles Marineris, Mars  

SciTech Connect

The emplacement of a sequence of deposits covering the chasma floors of the central Valles Marineris of Mars, ranging from thin dust to several km in thickness, appears to have been the last major formational event. These deposits fall into the categories of (1) dark patches lying along faults, (2) light-colored deposits locally associated with craters, and (3) mottled, rugged deposits. It is presently suggested that these materials may be of volcanic origin, in view of their low albedo, their association with faults and possible volcanic features, and their embayment relations and lobate margins. If the suggestion is true, then the occasionally explosive volcanism in question was associated with rifting in the Valles Marineris, and may be as young as the late Tharsis volcanism. 41 refs.

Lucchitta, B. K. (USGS, Flagstaff, AZ (USA))

1990-08-01

32

Mobility and topographic effects for large Valles Marineris landslides on Mars  

E-print Network

Mobility and topographic effects for large Valles Marineris landslides on Mars A. Lucas1,2 and A Martian landslides observed in Valles Marineris (VM). However, Martian normalized runout are twice are not strong enough to explain the high mobility of Martian landslides. As a result, other physical and

Lucas, Antoine

33

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

34

Are there carbonate deposits in the Valles Marineris, Mars  

SciTech Connect

The precipitation of 30 mbar of Martian atmosphere CO/sub 2/ as carbonates in lakes is suggested to be the source of thick sequences of layered deposits found in the Valles Marineris. Support is adduced for this scenario from processes occurring in the perennially frozen dry valley lakes of Antarctica, where the lake water is supersaturated with atmospheric gases. Atmospheric CO/sub 2/ would have accumulated in such Martian lakes as temperatures fell, and the presence of an insulating ice cover would have allowed liquid water to exist. 23 references.

Mckay, C.P.; Nedell, S.S.

1988-01-01

35

Fault geometries and extension in the Valles Marineris, Mars  

NASA Technical Reports Server (NTRS)

The central troughs of the Valles Marineris system on Mars are generally regarded to be of tectonic origin because they are linear and bounded by faults. Their radial orientation to the Tharsis rise suggests that at least their incipient formation was influenced by the formation of the rise, but the exact role of Tharsis is not yet well understood. Collapse and erosion may have significantly modified the original tectonic troughs. To better understand the magnitude and mechanism of crustal extension across the Valles Marineris, the attitudes of trough-wall faults that parallel the long axes of the troughs were studied. Our results will help to determine if the extension is related to the Tharsis rise, to a local arch along which the troughs lie, or to other mechanisms. Fault-plane attitudes were obtained by performing a photogrammetric study of fault traces in the walls of Candor and Melas Chasmata. If the exposed wall faults are not major trough-bounding faults, it is assumed that these major faults are buried at the base of the walls and have similar geometries to the exposed faults. Three dimensional coordinates of several points along each fault trace were obtained and three-point solutions to their geometries were constructed. As expected, the results show that the faults dip toward the interior of the troughs, suggesting that they are indeed normal faults associated with trough formation.

Chadwick, D. J.; Lucchitta, B. K.

1993-01-01

36

Optical depth and its scale-height in Valles Marineris from HRSC stereo images  

NASA Astrophysics Data System (ADS)

We measured the optical depth of the Martian atmosphere as a function of altitude above two opposing scree walls of the Valles Marineris, from stereo images that were taken with the High Resolution Stereo Camera (HRSC) of Mars Express on June 3, 2004, during orbit 471. The optical depths were measured from contrast differences between the stereo images with the so called "stereo method". For 7 regions in the northern wall of the Valles, we estimated the optical depth and found values between 1.0 and 1.6. These regions span more than 6 km in altitude and the results show a clear relation with altitude. A fit on these results yielded a scale-height for the optical depth of 14.0 km + 1.3/-1.1 km. The expected local pressure-scale height is smaller: 11.5-12.0 km. The difference is most likely explained by small (around 1.5%) offset errors in the intensity calibration of HRSC images. We also selected 9 regions in the opposing southern wall and from these we measured values of optical depth in the range 1.3-1.5. Our result suggests the presence of clouds above this part of the Valles because the optical depth appears almost independent of the surface altitude. Possibly these are banner clouds, forming at the edge of the canyon, that contain dust that is blown over the canyon by winds from the high plains to the South.

Hoekzema, N. M.; Garcia-Comas, M.; Stenzel, O. J.; Grieger, B.; Markiewicz, W. J.; Gwinner, K.; Keller, H. U.

2010-06-01

37

Dark materials in Valles Marineris: Indications of the style of volcanism and magmatism on Mars  

SciTech Connect

Rifting on the equatorial canyon system of Valles Marineris provides a unique view of the interior of the Martian crust to depths reaching 7 km, exposing several in situ bedrock units which testify to past volcanic and magmatic processes on Mars. A thick, regionally extensive deposit observed in Coprates and Juventae chasmata is interpreted on the basis of spectral reflectance, erosional morphology, and tendency for eolian mobilization to be composed of mafic glass, possibly an ancient Martian analogue of the lunar terra mantling deposits. Spectral mapping suggests that the dark floor-covering materials in the lower canyons are derived from this unit. A series of cliffs in the Ophir Chasma wall rock is interpreted to be exposures of resistant bedrock; the spectral signature of this massive and uniform unit most closely resembles that of terrestrial mafic rocks altered to or coated by crystalline hematite. Application of computer mapping techniques to probable young volcanic materials in the central troughs yields an inferred distribution of volcanic activity consistent with the interpretation of extrusion along faults near the margins of the canyon floors. This result supports the hypothesis that the valles originated through tectonic extension.

Geissler, P.E.; Singer, R.B. (Univ. of Arizona, Tucson (USA)); Lucchitta, B.K. (Geological Survey, Flagstaff, AZ (USA))

1990-08-30

38

New Evidence that the Valles Marineris Interior Layered Deposits Formed in Standing Bodies of Water  

NASA Technical Reports Server (NTRS)

Our results indicate that the best explanation for the origin and current morphology of the Valles Marineris interior layered deposits is by deposition of sediments, including chemical precipitates, in standing bodies of water.

Weitz, C. M.; Parker, T. J.

2000-01-01

39

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

40

Mobility of large rock avalanches: evidence from Valles Marineris, Mars  

USGS Publications Warehouse

Measurements of H/L (height of drop/length of runout) vs. volume for landslides in Valles Marineris on Mars show a trend of decreasing H/L with increasing volume. This trend, which is linear on a log-log plot, is parallel to but lies above the trend for terrestrial dry rock avalanches. This result and estimates of 104 to 105 Pa yield strength suggest that the landslides were not water saturated, as suggested by previous workers. The offset between the H/L vs. volume trends shows that a typical Martian avalanche must be nearly two orders of magnitude more voluminous than a typical terrestrial avalance in order to achieve the same mobility. This offset might be explained by the effects of gravity on flows with high yield strengths. These results should prove useful to future efforts to resolve the controversy over the mechanics of long-runout avalanches. -Author

McEwen, A.S.

1989-01-01

41

Implications of Flexural Flanks at the Valles Marineris, Mars  

NASA Technical Reports Server (NTRS)

The presence or absence of flexural flanks at the Valles Marineris (VM), Mars, have strong implications for the properties of the lithosphere, information which is critical for models of compensation state and formation of the troughs. Two hypotheses are favored for the formation of the VM, tectonic extension or subsurface withdrawal potentially related to dike emplacement; in either case, the formation of the large troughs at the VM requires a flexural response. After discussing preliminary models of flexure for VM from released Mars Global Surveyor (MGS) Mars Orbiting Laser Altimeter (MOLA) topography, this abstract considers the implications of flexure for gravity modeling and the lithosphere at VM. With future MGS topography and gravity data, and constraints on T(sub e) from this study, significantly better gravity modeling can be done to understand the state of the lithosphere at VM. Additional information is contained in the original extended abstract.

Anderson, F. S.; Banerdt, W. B.; Golombek, M. P.

1999-01-01

42

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

43

Hydrated mineral stratigraphy of Ius Chasma, Valles Marineris  

NASA Astrophysics Data System (ADS)

New high-resolution spectral and morphologic imaging of deposits on walls and floor of Ius Chasma extend previous geomorphic mapping, and permit a new interpretation of aqueous processes that occurred during the development of Valles Marineris. We identify hydrated mineralogy based on visible-near infrared (VNIR) absorptions. We map the extents of these units with CRISM spectral data as well as morphologies in CTX and HiRISE imagery. Three cross-sections across Ius Chasma illustrate the interpreted mineral stratigraphy. Multiple episodes formed and transported hydrated minerals within Ius Chasma. Polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma. They may have been precipitates in a closed basin or diagenetically altered after deposition. Fluvial or aeolian processes then deposited layered Fe/Mg smectite and hydrated silicate on the chasma floor, postdating the sulfates. The smectite apparently was weathered out of Noachian-age wallrock and transported to the depositional sites. The overlying hydrated silicate is interpreted to be an acid-leached phyllosilicate transformed from the underlying smectite unit, or a smectite/jarosite mixture. The finely layered smectite and massive hydrated silicate units have an erosional unconformity between them, that marks a change in surface water chemistry. Landslides transported large blocks of wallrock, some altered to contain Fe/Mg smectite, to the chasma floor. After the last episode of normal faulting and subsequent landslides, opal was transported short distances into the chasma from a few m-thick light-toned layer near the top of the wallrock, by sapping channels in Louros Valles. Alternatively, the material was transported into the chasma and then altered to opal. The superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential, distinct aqueous environments, characterized by alkaline, then circum-neutral, and finally very acidic surface or groundwater chemistry.

Roach, Leah H.; Mustard, John F.; Swayze, Gregg; Milliken, Ralph E.; Bishop, Janice L.; Murchie, Scott L.; Lichtenberg, Kim

2010-03-01

44

Analysis of Fault Lengths Across Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

Summary. As part of a larger project to determine the history of stress and strain across Valles Marineris, Mars, graben lengths located within the Valley are measured using a two-dimensional window-sampling method to investigate depth of faulting and accuracy of measurement. The resulting degree of uncertainty in measuring lengths (+19 km - 80% accuracy) is independent of the resolution at which the faults are measured, so data sets and resultant statistical analysis from different scales or map areas can be compared. The cumulative length frequency plots show that the geometry of Valley faults display no evidence of a frictional stability transition at depth in the lithosphere if mechanical interaction between individual faults (an unphysical situation) is not considered. If strongly interacting faults are linked and the composite lengths used to re-create the cumulative lengths plots, a significant change in slope is apparent suggesting the existence of a transition at about 35-65 km below the surface (assuming faults are dipping from 50deg to 70deg This suggests the thermal gradient to the associated 300-400degC isotherm is 53C/km to 12degC/km.

Fori, A. N.; Schultz, R. A.

1996-03-01

45

Stratigraphic evidence of past fluvial activity in southern Melas Chasma, Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

During the late Noachian and early Hesperian periods, listric faulting led to the development of a series of hanging depressions throughout the Valles Marineris canyon system [1]. One such depression, situated on the southern wall of Melas Chasma, forms an enclosed basin which has since undergone modification from the late Hesperian to Amazonian. There is a multitude of evidence suggesting that the basin (hereon in referred to as the Southern Melas Chasma Basin; SMCB) was once host to active fluvial processes, that at minimum lasted for several hundred years [2,3]. Central to this is what appears to be the remains of a palaeolake, which is approximately 80 by 40 kilometres in area. The palaeolake contains a complex sequence of sedimentary stratigraphy, which includes several structures that resemble deltas and/or submarine fans on both the east and west side of the basin [4], and appear to originate from a network of channels and valleys that terminate in the basin. Previous studies have shown that the western valley network has drainage densities similar to terrestrial values and a dendritic nature that is indicative of precipitation and surface runoff [3]. Higher resolution mapping of the SMCB is important to further understand the stratigraphic succession and geomorphology, and to quantify how long liquid water may have been present within the basin. For this study, new digital elevation models (DEMs) have been produced in SOCET SET using stereo images from the Context Camera (CTX) and the High Resolution Imaging Science Experiment (HiRISE), both aboard the Mars Reconnaissance Orbiter. The DEMs have been produced at ~6 and ~1 m/pixel vertical resolution for CTX and HiRISE respectively. There is approximately 150-200 m of sediment within the stratigraphic succession; some individual strata are less than 10 m thick. The delta/fan structures appear to occur at different stratigraphic positions low down within the sequence. Clinoform-like and cross-bedded structures are shown to occur near the top of the sequence (a contrast to the laterally expansive, planar beds below), which suggest a significant change in depositional conditions within the SMCB during the time liquid water was stable. References: 1. Andrews-Hanna, J. C. The formation of Valles Marineris: 3. Trough formation through super-isostasy, stress, sedimentation, and subsidence. J. Geophys. Res. 117, E06002 (2012). 2. Mangold, N., Quantin, C., Ansan, V., Delacourt, C. & Allemand, P. Evidence for precipitation on Mars from dendritic valleys in the Valles Marineris area. Science 305, 78-81 (2004). 3. Quantin, C. Fluvial and lacustrine activity on layered deposits in Melas Chasma, Valles Marineris, Mars. J. Geophys. Res. 110, E12S19 (2005). 4. Metz, J. M. et al. Sublacustrine depositional fans in southwest Melas Chasma. J. Geophys. Res. 114, E10002 (2009).

Davis, Joel; Grindrod, Peter

2014-05-01

46

Mineralogical and morphological study of the chaotic terrains of Valles Marineris, Mars: Insights into their geologic history  

NASA Astrophysics Data System (ADS)

Following the OMEGA/Mars Express discovery of sulfates in the Valles Marineris area, a wide range of data, including the recent CRISM (The Compact Reconnaissance Imaging Spectrometer for Mars) observations, has been used to refine these detections. The present study focuses on three chasmata located at the border between the eastern end of Valles Marineris and at the onset of the chaotic terrains of Margaritifer Terra. Ganges Chasma, Capri Chasma and Juventae Chasma all share common features with the chaotic terrains, such as collapse plateaus and chaotic mounds, suggesting a aqueous history, but they are also affected by the east-west extensive tectonics of Valles Marineris and are thus considered part of the rift system. OMEGA and CRISM surveys show that, similarly to the rest of Valles Marineris, these three chasmata are filled with thick, massive sulfate-rich interior layered deposits (ILDs). A succession of a Mg monohydrated sulfate rich unit (characterized by diagnostic absorptions at 2.13 and 2.4 ?m) capped by a polyhydrated sulfate rich unit (1.9 and 2.4 ?m absorptions) is generally observed (Bishop et al., 2009; Flahaut et al., 2010). However, a number of other spectral features are noted, as additional absorptions between 2.2 and 2.3 ?m which could indicate the presence of hydrated silicates (clays or opaline silica) or additional ferric sulfates (e.g., Flahaut et al., 2010). More polyhydrated sulfates might be present as thin layers down in the ILD section in both Capri and Ganges Chasmata. The ILDs are distributed as mesas that might have been more extensive in the past, and that are overlapping the chaotic floor. CRISM data show that Fe/Mg-bearing phyllosilicates are detected in the upper part of the chaotic knobs that form the floor, thanks to their sharp 1.9 and 2.3 ?m spectral features. The mounds are surrounded by abundant dark sands forming ergs. CRISM spectra show a wide 1 ?m absorption feature, associated to weaker 2 ?m absorptions. This suggests that this sand is enriched in olivine, mixed with a high calcium pyroxene. It was previously suggested that this sand could potentially derive from the canyon walls (Chojnacki et al., 2012). However, it is not as abundant in other chasmata of Valles Marineris, suggesting a chaos-related origin. We argue that its source could be the extensive olivine-rich layer that is present in Margaritifer Terra and is exposed on the floor of at least eastern Capri and Ganges Chasmata (Flahaut et al., 2012). The units bearing these different signatures have different ages, allowing us to propose a reconstruction of part of the history of Valles Marineris. This history implies multiple water discharge episodes, during but also after the chaos emplacement, in the Hesperian and Amazonian periods. The water-rich history of this area, coupled with the unique geological record of Valles Marineris make these three chasmata prime targets for future Mars exploration.

Flahaut, J.; Bishop, J. L.; Fueten, F.; Quantin, C.; Van Westrenen, W.; Davies, G. R.

2013-12-01

47

Layers within the Valles Marineris: Clues to the Ancient Crust of Mars - High Resolution Image  

NASA Technical Reports Server (NTRS)

This high resolution picture of the Martian surface was obtained in the early evening of January 1, 1998 by the Mars Orbiter Camera (MOC), shortly after the Mars Global Surveyor spacecraft began it's 80th orbit. Seen in this view are a plateau and surrounding steep slopes within the Valles Marineris, the large system of canyons that stretches 4000 km (2500 mi) along the equator of Mars. The image covers a tiny fraction of the canyons at very high resolution: it extends only 9.8 km by 17.3 km (6.1 mi by 10.7 mi) but captures features as small as 6 m (20 ft) across. The highest terrain in the image is the relatively smooth plateau near the center. Slopes descend to the north and south (upper and lower part of image, respectively) in broad, debris-filled gullies with intervening rocky spurs. Multiple rock layers, varying from a few to a few tens of meters thick, are visible in the steep slopes on the spurs and gullies. Layered rocks on Earth form from sedimentary processes (such as those that formed the layered rocks now seen in Arizona's Grand Canyon) and volcanic processes (such as layering seen in the Waimea Canyon on the island of Kauai). Both origins are possible for the Martian layered rocks seen in this image. In either case, the total thickness of the layered rocks seen in this image implies a complex and extremely active early history for geologic processes on Mars.

Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1998-01-01

48

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

49

Volcanism inside Valles Marineris? A field of small pitted cones in Coprates Chasma  

NASA Astrophysics Data System (ADS)

We present observations of a field of more than 100 pitted cones and mounds situated insight Coprates Chasma (part of Valles Marineris; Fig. 1), which bear many morphological and morphometrical similarities to terrestrial and martian scoria cones. If these cones are indeed volcanic in origin, they will significantly expand our knowledge about the morphometry of pyroclastic cones on Mars. A magmatic origin, which would necessarily post-date the opening of the main troughs, would contribute to our understanding of the volcano-tectonic evolution of Valles Marineris.

Broz, P.; Hauber, E.; Rossi, A. P.

2014-04-01

50

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

51

MEVTV study: Early tectonic evolution of Mars: Crustal dichotomy to Valles Marineris  

NASA Technical Reports Server (NTRS)

Several fundamental problems were addressed in the early impact, tectonic, and volcanic evolution of the martian lithosphere: (1) origin and evolution of the fundamental crustal dichotomy, including development of the highland/lowland transition zone; (2) growth and evolution of the Valles Marineris; and (3) nature and role of major resurfacing events in early martian history. The results in these areas are briefly summarized.

Frey, Herbert V.; Schultz, Richard A.

1990-01-01

52

Erosion and tectonics in Central Valles Marineris (Mars): a new morpho-structural model  

Microsoft Academic Search

In order to explain the development of Central Valles Marineris, a new morphostructural model is proposed. This model involves three major phases, including (i) initiation of graben patterns and pit crater chains under an early extensional phase, (ii) formation of wide grabens during major faulting, local rifting, and erosional phase, (iii) late faulting and secondary volcanic activity, possibly related to

J. P. Peulvast; Ph. L. Masson

1993-01-01

53

MEVTV study: Early tectonic evolution of Mars: Crustal dichotomy to Valles Marineris  

Microsoft Academic Search

Several fundamental problems were addressed in the early impact, tectonic, and volcanic evolution of the martian lithosphere: (1) origin and evolution of the fundamental crustal dichotomy, including development of the highland\\/lowland transition zone; (2) growth and evolution of the Valles Marineris; and (3) nature and role of major resurfacing events in early martian history. The results in these areas are

Herbert V. Frey; Richard A. Schultz

1990-01-01

54

Melas Chasma - Morphology and tectonic patterns in Central Valles Marineris (Mars)  

Microsoft Academic Search

The central Valles Marineris is the widest part of the equatorial trough system of Mars. Melas Chasma and parts of Coprates and Candor Chasmata provide some of the clearest clues on the relationships between erosional landforms, deposits, and various volcanic and tectonic features. A detailed geomorphic study of the troughs allows the identification of faults and other structures in most

J. P. Peulvast; Ph. L. Masson

1993-01-01

55

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

56

On the Morphology and Transition of Valles Marineris Landforms: Rock Glaciers/Protalus Lobes vs. Landslides  

NASA Astrophysics Data System (ADS)

The Valles Marineris canyon system exhibits a variety of different landforms associated with landslide mechanisms, ranging from several tens of meters to kilometers in length. They usually cover a surface of 1000 km2 and have an average volume of up to 5000 km3 [1-2]. It is assumed that they have been emplaced under wet as well as dry conditions from destabilized wall-rock and from surrounding sapping valleys [e.g., 1-3]. Absolute age determinations have furthermore shown that landslides in Valles Marineris span much of Martian history with ages as young as 50 Myr up to 3.5 Gyr [1]. Notwithstanding their individual ages and timespan during which they have been emplaced, landslides seem to have formed repetitively producing comparable morphologies and do not show substantial modifications throughout the last 3.5 Gy [1]. We here put our focus on a set of complex tongue-shaped landforms situated in the central parts of Valles Marineris at 283 °E, 8 °S which were previously identified as a single feature and for which a possible rock-glacier origin had been proposed [5]. This assumption implies environmental conditions which are not met today at such latitudes near the equator and which would contradict all observations related to the distribution of periglacial landforms on Mars, such as thermal contraction polygons, thermokarst features, and -- especially — lobate debris aprons [e.g., 6-11] which are considered to be Martian analogues for terrestrial rock glaciers. On the basis of our observations we come to the conclusion that the landforms discussed herein form a complex set of landslides derived from wall-rock sliding and/or from surrounding valleys. Consequently, different sources areas are reflected by the complexity of the landslides with several overlapping lobes and individual tongue-shaped features. Although the tongue-shaped morphology is characteristic of rock-glacier landforms, the assembly of furrows and ridges strongly suggests an origin caused by several short-termed events rather than slow creep mechansims. Overlapping lobes and faint compressional ridges as seen at this location are not caused by creep of mountain debris but by multiple events that took place at least as early as 300 Myr ago (with several resurfacing events) as crater counts suggest. Morphometric characteristics fit quite well to the trends proposed by others for landforms indicative of landsliding [12-13]. [1] C. Quantin et al. Icarus, 172:555-572, 2004. [2] C. Quantin et al. Planet. Space Sci., 52:1011-1022, 2004. [3] B. K. Lucchitta. J. Geophys. Res., 84(B14):8097-8113, 1979. [4] A. Lucas and A. Mangeney. Geophys. Res. Lett., 34:L10201, 2007. [5] W. Brian Whalley and Fethi Azizi. J. Geophys. Res., 108:E048032, 2003. [6] S. W. Squyres. Icarus, 34:600-613, June 1978. [7] S. W. Squyres. J. Geophys. Res., 84:8087-8096, December 1979. [8] N. Mangold et al. Planet. Space Sci., 50:385-401, 2002. [9] N. Mangold. Journal of Geophysical Research (Planets), 108:8021, 2003. [10] F. C. Chuang and D. A. Crown. Icarus, 179:24-42, December 2005. [11] H. Li et al. Icarus, 176: 382-394, 2005.[12] A. S. McEwen. Geology, 17:1111-1114, 1989. [13] K. P. Harrison and R. E. Grimm. Icarus, 163:247-362, 2003.

van Gasselt, S.; Hauber, E.; Dumke, A.; Schreiner, B.; Neukum, G.

2009-04-01

57

Western Tithonium Chasma/Ius Chasma, Valles Marineris - High Resolution Image  

NASA Technical Reports Server (NTRS)

Most remarkable about this MOC image is the discovery of light and dark layers in the rock outcrops of the canyon walls. In the notable, triangular mountain face (at center), some 80 layers, typically alternating in brightness and varying in thickness from 5 to 50 meters (16 to 160 feet), are clearly visible. This shear mountain cliff, over 1000 m (3200 ft) tall, is only one of several outcrops that, together, indicate layering almost the entire depth of the canyon.

This type of bedrock layering has never been seen before in Valles Marineris. It calls into question common views about the upper crust of Mars, for example, that there is a deep layer of rubble underlying most of the martian surface, and argues for a much more complex early history for the planet.

Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. The original mission plan called for using friction with the planet's atmosphere to reduce the orbital energy, leading to a two-year mapping mission from close, circular orbit (beginning in March 1998). Owing to difficulties with one of the two solar panels, aerobraking was suspended in mid-October and resumed in November 8. Many of the original objectives of the mission, and in particular those of the camera, are likely to be accomplished as the mission progresses.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1997-01-01

58

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

59

Layers within the Valles Marineris: Clues to the Ancient Crust of Mars  

NASA Technical Reports Server (NTRS)

This high resolution picture (right) of the Martian surface was obtained in the early evening of January 1, 1998 by the Mars Orbiter Camera (MOC), shortly after the Mars Global Surveyor spacecraft began it's 80th orbit. Seen in this view are a plateau and surrounding steep slopes within the Valles Marineris, the large system of canyons that stretches 4000 km (2500 mi) along the equator of Mars. The image covers a tiny fraction of the canyons at very high resolution: it extends only 9.8 km by 17.3 km (6.1 mi by 10.7 mi) but captures features as small as 6 m (20 ft) across. The highest terrain in the image is the relatively smooth plateau near the center. Slopes descend to the north and south (upper and lower part of image, respectively) in broad, debris-filled gullies with intervening rocky spurs. Multiple rock layers, varying from a few to a few tens of meters thick, are visible in the steep slopes on the spurs and gullies. Layered rocks on Earth form from sedimentary processes (such as those that formed the layered rocks now seen in Arizona's Grand Canyon) and volcanic processes (such as layering seen in the Waimea Canyon on the island of Kauai). Both origins are possible for the Martian layered rocks seen in this image. In either case, the total thickness of the layered rocks seen in this image implies a complex and extremely active early history for geologic processes on Mars.

The left and center 'context' images are Viking mosaics reproduced at scales of 230 meters/pixel and 80 meters/pixel respectively. Outlines in these two images represent the location of the higher resolution image(s).

Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1998-01-01

60

Strike-slip faulting of ridged plains near Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

This paper identifies and documents several well-preserved examples of Martian strike-slip faults and examines their relationships to wrinkle-ridges. The strike-slip faulting predates or overlaps periods of wrinkle-ridge growth southeast of Valles Marineris, and some wrinkle ridges may have nucleated and grown as a result of strike-slip displacements along the echelon fault arrays. Lateral displacements of several km inferred along these arrays may be related to tectonism in Tharsis.

Schultz, R. A.

1989-10-01

61

Interior Layered Deposits in Valles Marineris, Mars: Insights From 3d-Data Obtained by the High Resolution Stereo Camera (HRSC) on Mars Express  

Microsoft Academic Search

The Interior Layered Deposits (ILD) in the Valles Marineris depressions on Mars may be of volcanic or sedimentary origin. Either way, their presence has profound implications for the formation of the Valles Marineris itself. The High Resolution Stereo Camera (HRSC) on board the Mars Express mission obtains high-resolution stereo and multipectral images, which are particularly well suited for the geomorphologic

E. Hauber; K. Gwinner; R. M. Stesky; F. Fueten; G. Michael; D. Reiss; H. Hoffmann; R. Jaumann; G. Neukum; T. Zegers

2004-01-01

62

Thin-skinned deformation of sedimentary rocks in Valles Marineris, Mars  

USGS Publications Warehouse

Deformation of sedimentary rocks is widespread within Valles Marineris, characterized by both plastic and brittle deformation identified in Candor, Melas, and Ius Chasmata. We identified four deformation styles using HiRISE and CTX images: kilometer-scale convolute folds, detached slabs, folded strata, and pull-apart structures. Convolute folds are detached rounded slabs of material with alternating dark- and light-toned strata and a fold wavelength of about 1 km. The detached slabs are isolated rounded blocks of material, but they exhibit only highly localized evidence of stratification. Folded strata are composed of continuously folded layers that are not detached. Pull-apart structures are composed of stratified rock that has broken off into small irregularly shaped pieces showing evidence of brittle deformation. Some areas exhibit multiple styles of deformation and grade from one type of deformation into another. The deformed rocks are observed over thousands of kilometers, are limited to discrete stratigraphic intervals, and occur over a wide range in elevations. All deformation styles appear to be of likely thin-skinned origin. CRISM reflectance spectra show that some of the deformed sediments contain a component of monohydrated and polyhydrated sulfates. Several mechanisms could be responsible for the deformation of sedimentary rocks in Valles Marineris, such as subaerial or subaqueous gravitational slumping or sliding and soft sediment deformation, where the latter could include impact-induced or seismically induced liquefaction. These mechanisms are evaluated based on their expected pattern, scale, and areal extent of deformation. Deformation produced from slow subaerial or subaqueous landsliding and liquefaction is consistent with the deformation observed in Valles Marineris.

Metz, Joannah; Grotzinger, John; Okubo, Chris; Milliken, Ralph

2010-01-01

63

Fault-Continuation Ridges in the Valles Marineris, Mars: Evidence for Groundwater Circulation  

NASA Astrophysics Data System (ADS)

The walls of the Valles Marineris (VM) are marked in many places by high-standing ridges that continue the traces of graben bounding faults on the plains adjacent to the VM. These fault-continuation ridges (FCR) are most prominent at Melas Labes and Candor Labes, where they form the boundaries between Ophir, Melas, and Candor Chasmae. FCR are as long as 100 km, and extend from the plains surfaces downward about 3-6 km in elevation. Available data suggests that FCR are fault zones cemented and hardened by groundwater deposits.

Treiman, A. H.; Spiker, K.

1996-03-01

64

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.

65

Ferric oxides in East Candor Chasma, Valles Marineris (Mars) inferred from analysis of OMEGA/Mars Express data  

E-print Network

) inferred from analysis of OMEGA/Mars Express data: Identification and geological interpretation, J. Geophys (Observatoire pour la Mine´ralogie, l'Eau, les Glaces et l'Activite´) imaging spectrometer onboard Mars ExpressFerric oxides in East Candor Chasma, Valles Marineris (Mars) inferred from analysis of OMEGA/Mars

Mege, Daniel

66

Continental-Scale Salt Tectonics on Mars and the Origin of Valles Marineris and Associated Outflow Channels  

Microsoft Academic Search

A synthesis of regional deformation patterns of the Thaumasia Plateau, Mars, leads to a new interpretation for regional deformation and the origin of Valles Marineris and associated outflow channels. The morphology of the Thaumasia Plateau is typical of thin-skinned deformation, akin to a \\

D. R. Montgomery; S. M. Som; B. C. Schreiber; M. P. Jackson; A. R. Gillespie; J. B. Adams

2007-01-01

67

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

68

Extensive surface pedogenic alteration of the Martian Noachian crust suggested by plateau phyllosilicates around Valles Marineris  

NASA Astrophysics Data System (ADS)

Thousands of phyllosilicate-rich outcrops, mainly iron or magnesium-rich are exposed on Noachian terrains in the Martian southern highlands. We analyzed 90 CRISM observations and more than a hundred HiRISE images located on the plateaus surrounding Valles Marineris. We mapped an extensive Al- and Fe/Mg-phyllosilicate-rich formation covering at least ˜197,000 km2, for which we introduce the name “Plateau Phyllosilicates.” Tens of meters in thickness, this light-toned formation crops out at various elevations on top of the Noachian units Npl1 and Npl2, as flat exposures on plateaus and along scarps such as valley walls, chasma walls, pit walls and impact crater rims. The Fe/Mg-phyllosilicate-rich lower member of the formation is composed of Fe/Mg-smectites (nontronite, saponite) and vermiculite. The Al-phyllosilicate-rich upper member of the formation contains Al-smectites (montmorillonite, beidellite) and locally kaolinite and/or halloysite. We suggest that the Plateau Phyllosilicates were mainly formed by pedogenesis related to the weathering of the Noachian bedrock by percolation of meteoric water or melted snow under a temperate and subarid climate during the Noachian Epoch in an alkaline to neutral environment. Kaolinite and/or halloysite may have formed in areas of more intense drainage at the surface under slightly acidic environments during the Noachian and Hesperian Epochs. Fluvial activity and deuteric alteration may have locally contributed to the genesis of phyllosilicates. This study suggests that the alteration of the Noachian basement of the plateaus surrounding Valles Marineris was widespread during the Noachian Epoch, and was still active during the Hesperian Epoch even though the water availability was limited.

Le Deit, Laetitia; Flahaut, Jessica; Quantin, Cathy; Hauber, Ernst; Mège, Daniel; Bourgeois, Olivier; Gurgurewicz, Joanna; Massé, Marion; Jaumann, R.

2012-03-01

69

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

70

A Window into the History of Valles Marineris From Magnetic Field Measurement Analysis  

NASA Astrophysics Data System (ADS)

Analysis and interpretation of magnetic field measurements can shed new light into the formation and evolution of Valles Marineris, one of the largest extensional features in the solar system. Valles Marineris is generally only weakly magnetized; the magnetic field is lower than ~20 nT at mapping orbit altitude over the western and central parts However, there are strong fields (~200 nT for low altitudes and ~50 nT at high altitudes) present in the eastern part; Xanthe Terra (to the north) and Nectaris Fossae (to the south) both have strong fields associated with them. Within these magnetized regions, Capri Mensa and the eastern portion of Coprates Chasma appear to be demagnetized. Capri Mensa is a mesa within Capri Chasma that is dated to be Hesperian in age, so the apparent demagnetization (or weaker magnetization) could be related to geologic processes that occurred when this feature formed. In contrast, Eos Mensa is more strongly magnetized than Capri Mensa and is dated to be Noachian. Coprates Chasma is demagnetized, but it is farther west and closer to Tharsis, so it is likely that magmatism-related thermal effects demagnetized this part of the crust. There is an apparent lack of magnetization associated with Shalbatana Vallis. We use inverse local Equivalent Source Dipoles methods to constrain the direction and intensity of magnetization of sources in this area. We also investigate lateral variations of the magnetized layer thickness to test if magnetic material was removed during chasmata formation. Detailed results of magnetic modeling will be presented.

Milbury, C.; Langlais, B.

2012-12-01

71

Origin of Valles Marineris and Noctis Labyrinthus, Mars, by structurally controlled collapse and erosion of crustal materials  

NASA Astrophysics Data System (ADS)

Stratigraphic, structural, and geomorphologic relations indicate that the Valles Marineris (VM) and Noctis Labyrinthus troughs on Mars began their development in the Noachian as narrow grabens in response to Tharsis-centered stress and local magmatism. Following an apparent waning of VM tectonism during the Early Hesperian, the major trough-forming episode ensued during the Late Hesperian and Early Amazonian due to fluidization, collapse, and erosion of water-saturated, poorly consolidated crustal rocks through channels and subsurface conduits.

Tanaka, Kenneth L.

1997-03-01

72

Putative Large and Small Volcanic Edifices in Valles Marineris, Mars, and Evidence of Ground Water\\/Ice  

Microsoft Academic Search

Large mounds and mesas of interior layered deposits (ILDs) in Valles Marineris Chasmata have been suggested to be sub-ice volcanoes based on MGS and Viking data [1,2,3]. Similar to terrestrial sub-ice volcanoes, spectral investigation indicates the bright mounds are hydrothermally altered, palagonitic rocks [4]. These putative edifices are associated with outcrops of dark materials that have each been interpreted previously

M. G. Chapman; J. L. Smellie

2001-01-01

73

Low H/L of initial and secondary landslides on Mars Valles Marineris floor  

NASA Astrophysics Data System (ADS)

The Mars Global Surveyer (MGS) has investigated the almost whole Martian topography with high resolution and its products are reflected in the Google Earth's martian option. This digital service provide huge opportunities to public to view the preserved landslide topography as well as to measure the parameters for landslide mobility such as average coefficient of friction (H/L), and apparent friction angle. Among those views, the Valles Marineris is the most landslide prone area and a lot of long runout gigantic landslides can be extracted along the tectonic cliff. Authors encouraged undergraduate students to measure this parameter as an exercise of introductory course of planetary science, especially of the gigantic initial landslides to compare with those of secondary landslides which looks like induced by subsequent triggers such as earthquake or metor impact. Preliminary results show that (1) The H/L values of the gigantic initial landslides are dependent on landslide volume as reported by previous studies; (2) secondary landslides of much less volumes generally have wide and thin spread features but much smaller friction like debris flows. Those characters imply that those landslides might have been induced in the landslide deposits of higher moisture content and/or runout on valley floor of highly saturated or shallow ground water table.

Sagi, H.; Fukuoka, H.

2012-12-01

74

Diagenetic Layers in the Upper Walls of Valles Marineris, Mars: Evidence for Drastic Climate Change Since the Mid-Hesperian  

NASA Technical Reports Server (NTRS)

A packet of relatively resistant layers, totaling approx. 400 m thickness, is present at the tops of the chasma walls throughout Valles Marineris. The packet consists of an upper dark layer (approx. 50 m thick), a central bright layer (approx. 250 m thick), and a lower dark layer (approx. 100 m thick). The packet appears continuous and of nearly constant thickness and depth below ground surface over the whole Valles system (4000 km E-W, 800 km N-S), independent of elevation (3-10 km) and age of plateau surface (Noachian through upper Hesperian). The packet continues undisturbed beneath the boundary between surface units of Noachian and Hesperian ages, and continues undisturbed beneath impact craters transected by chasma walls. These attributes are not consistent with layer formation by volcanic or sedimentary deposition, and are consistent with layer formation in situ, i.e., by diagenesis, during or after upper Hesperian time. Diagenesis seems to require the action of aqueous solutions in the near subsurface, which are not now stable in the Valles Marineris area. To permit the stability of aqueous solutions, Mars must have had a fairly dense atmosphere, greater than or equal to 1 bar CO2, when the layers formed. Obliquity variations appear to be incapable of producing such a massive atmosphere so late in Mars' history.

Treiman, Allan H.; Fuks, Kelly H.; Murchie, Scott

1995-01-01

75

Continental-Scale Salt Tectonics on Mars and the Origin of Valles Marineris and Associated Outflow Channels  

NASA Astrophysics Data System (ADS)

A synthesis of regional deformation patterns of the Thaumasia Plateau, Mars, leads to a new interpretation for regional deformation and the origin of Valles Marineris and associated outflow channels. The morphology of the Thaumasia Plateau is typical of thin-skinned deformation, akin to a "mega-slide," in which extensional deformation in Syria Planum and Noctis Labyrinthus connects via zones of lateral transtension - Claritas Fossae and Valles Marineris - to a broad zone of compressional uplift and shortening defined by truncated craters and thrust faults along the Coprates Rise and Thaumasia Highlands. However, the low regional slope (?1°) results in gravitational body forces that are too small to deform the basaltic lava flows conventionally thought to compose the flanks of the Tharsis volcanic province. Instead, we conclude that geothermal heating and topographic loading of extensive buried deposits of salts (or mixtures of salts, ice, and basaltic debris) would allow for weak detachments and large-scale gravity spreading. We propose that the generally linear chasmata of Valles Marineris reflect collapse and excavation along pre-existing extension fractures radial to Tharsis, reactivated as part of one lateral margin of the Thaumasia gravity spreading system. The other, dextral, lateral margin is a massive splay of extensional faults forming the Claritas Fossae, which resembles a trailing extensional imbricate fan. The compressional mountain belt defined by the Coprates Rise and Thaumasia Highlands forms the toe of the "mega-slide." Topographic observations and previous structural analyses reveal evidence for a failed volcanic plume below Syria Planum that could have provided both thermal energy and topographic potential for initiating regional deformation. Increased geothermal heating over time, or heating simply due to increasing depth in the crust due to continuing burial, would have contributed to flow of salt deposits, as well as formation of groundwater from melting ice and dewatering hydrous salts. We further propose that connection of overpressured groundwater from aquifers near the base of the detachment through the cryosphere to the martian surface created the outflow channels of Echus, Coprates and Juventae chasmata at relatively uniform source elevations along the northern margin of the "mega-slide" where regional groundwater flow would have been directed toward the surface. Our hypothesis provides a unifying framework to explain perplexing relationships between the rise of the Tharsis volcanic province, deformation of the Thaumasia Plateau, and the formation of Valles Marineris and associated outburst floods.

Montgomery, D. R.; Som, S. M.; Schreiber, B. C.; Jackson, M. P.; Gillespie, A. R.; Adams, J. B.

2007-12-01

76

Reassessing rock mass properties and slope instability triggering conditions in Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

The rock walls of the Valles Marineris valleys (VM) in the equatorial area of Mars exhibit several gravitational failures which resulted in a series of large landslides up to several hundred cubic kilometers in volume. Questions arise as to forces at play and rock strength in the stability of the walls of VM. In this work we address the stability analysis of the walls of VM by considering the strength of the materials of the walls and the causes of landslides. Using finite element calculations and the limit analysis upper bound method, we explore the range of cohesion and friction angle values associated with realistic failure geometries, and compare predictions with the more classical Culmann's translational failure model. Our analysis is based both on synthetic, simplified slope profiles, and on the real shape of the walls of VM taken from the MOLA topographic data. Validation of the calibrated cohesion and friction angle values is performed by comparing the computed unstable cross sectional areas with the observed pre- and post-failure profiles, the estimated failure surface geometry and ridge crest retreat. This offers a link between rock mass properties, slope geometry and volume of the observed failure, represented in dimensionless charts. The role of groundwater flow and seismic action on the decrease of slope stability is also estimated. Pseudo-static seismic analyses provide another set of dimensionless charts and show that low seismicity events induced by meteoroid impacts, consistent with the size of craters, could be a cause for some of the observed landslides, if poor rock properties for VM are assumed. Analyses suggest that rock mass properties are more similar to their earth equivalents with respect to what has been previously supposed.

Crosta, Giovanni Battista; Utili, Stefano; De Blasio, Fabio Vittorio; Castellanza, Riccardo

2014-02-01

77

Ferric oxides in East Candor Chasma, Valles Marineris (Mars) inferred from analysis of OMEGA\\/Mars Express data: Identification and geological interpretation  

Microsoft Academic Search

The mineralogical composition of the Martian surface is constrained by analyzing the data of the OMEGA visible and near infrared imaging spectrometer onboard Mars Express. Ferric signatures had previously been reported in Valles Marineris, Margaritifer Terra, and Terra Meridiani. Here we use three independent data reduction methods (Spectral Angle Mapper, a modified Spectral Mixture Analysis and Modified Gaussian Model) to

Laetitia Le Deit; Stéphane Le Mouélic; Olivier Bourgeois; Jean-Philippe Combe; Daniel Mège; Christophe Sotin; Aline Gendrin; Ernst Hauber; Nicolas Mangold; Jean-Pierre Bibring

2008-01-01

78

Mapping, classification, and statistics of mass movements in Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

An unprecedented spatial detail of the Mars surface is accessible using high and ultra-high-resolution images and data by the High-Resolution Stereo Camera (HRSC) on-board the ESA Mars Express satellite, by the Mars Orbiter Laser Altimeter (MOLA), on-board the NASA Mars Global Surveyor, and by the High Resolution Imaging Science Experiment (HiRISE) camera on-board the NASA Mars Reconnaissance Orbiter. The images have spatial resolutions adequate to detect and map mass movements, allowing for the compilation of a nearly complete geomorphological landslide inventory, above a minimum size threshold. In the study area located in Valles Marineris, we visually identified and mapped 179 landslides (including escarpments, source areas, and deposits) using interpretation criteria adopted by geomorphologists to map terrestrial landslides. This is a significantly larger number of slope failures than previously reported. Areas of the individual failures span in the range 1.3×10^5 m^2 < A < 2.6×10^9 m^2. Adopting a classification commonly used to catalogue terrestrial mass movements, slope failures recognized and mapped in the study area were classified in three main types: (i) deep-seated slides, including rock slides, complex and compound failures, (ii) flows, including shallow debris flows and debris avalanches, and deep-seated rock avalanches, and (iii) rock glaciers. For mass movements of the slide type, multiple generations of failures were recognized. For a subset of 76 mass movements of the slide type, including deep-seated slides, rock slides, complex and compound failures we have determined the planimetric area in a GIS. For 46 slides we have estimated the volume of the deposit. Using this information, we obtained the probability density of the landslide areas, p(A), and of the landslide volumes, p(V), and compared it with the corresponding probability density of terrestrial landslides. We found that: (a) mass movements of the slide type on Mars are significantly larger than similar mass movements on Earth, (b) the proportion of very large landslides (A > 10^7 m^2), compared to the small and medium size failures, is significantly larger on Mars than on Earth, while (c) the distribution of landslide volumes is similar to that found on Earth.

Brunetti, M.; Cardinali, M.; Fiorucci, F.; Guzzetti, F.; Santangelo, M.; Mancinelli, P.; Komatsu, G.; Goto, K.; Saito, H.

2011-12-01

79

The Confluence of Gangis and Eos Chasmas (5-12 deg S, 31-41 deg W): Geologic, Hydrologic, and Exobiologic Considerations for Landing Site at the East End of Valles Marineris  

NASA Astrophysics Data System (ADS)

Over its 3,500 km length, Valles Marineris exhibits an enormous range of geologic and environmental diversity. At its western end, the canyon is dominated by the tectonic complex of Noctis Labyrinthus; while in the east it grades into an extensive region of chaos where scoured channels and streamlined islands provide evidence of catastrophic floods that spilled into the northern plains. In the central portion of the system, debris derived from the massive interior layered deposits of Candor and Ophir Chasmas spills into the central trough. In other areas, 6 km-deep exposures of Hesperian and Noachian-age canyon wall stratigraphy have collapsed in massive landslides that extend many tens of kilometers across the canyon floor. Ejecta from interior craters, aeolian sediments, and possible volcanics emanating from structurally controlled vents along the base of the scarps, further contribute to the canyon's geologic complexity. Following the initial rifting that gave birth to Valles Marineris, water appears to have been a principal agent in the canyon's geomorphic development an agent whose significance is given added weight by its potential role in both sustaining and preserving evidence of past life. In this regard, the interior layered deposits of Candor, Ophir, and Hebes Chasmas, have been identified as possible lucustrine sediments that may have been laid down in long-standing ice-covered lakes. The potential survival and growth of native organisms in such an environment, or in the aquifers whose disruption gave birth to the chaotic terrain and outflow channels to the north and east of the canyon, raises the possibility that fossil indicators of life may be present in the local sediment and rock. Because of the enormous distances over which these diverse environments occur, identifying a single landing site that maximizes the opportunity for scientific return is not a simple task. However, given the fluvial history and narrow geometry of the canyon, the presence of a single exit at its eastern end provides an opportunity for sampling that appears unequaled elsewhere in the system.

George, J. A.; Clifford, S. M.

1999-06-01

80

The Confluence of Gangis and Eos Chasmas (5-12 deg S, 31-41 deg W): Geologic, Hydrologic, and Exobiologic Considerations for Landing Site at the East End of Valles Marineris  

NASA Technical Reports Server (NTRS)

Over its 3,500 km length, Valles Marineris exhibits an enormous range of geologic and environmental diversity. At its western end, the canyon is dominated by the tectonic complex of Noctis Labyrinthus; while in the east it grades into an extensive region of chaos where scoured channels and streamlined islands provide evidence of catastrophic floods that spilled into the northern plains. In the central portion of the system, debris derived from the massive interior layered deposits of Candor and Ophir Chasmas spills into the central trough. In other areas, 6 km-deep exposures of Hesperian and Noachian-age canyon wall stratigraphy have collapsed in massive landslides that extend many tens of kilometers across the canyon floor. Ejecta from interior craters, aeolian sediments, and possible volcanics emanating from structurally controlled vents along the base of the scarps, further contribute to the canyon's geologic complexity. Following the initial rifting that gave birth to Valles Marineris, water appears to have been a principal agent in the canyon's geomorphic development an agent whose significance is given added weight by its potential role in both sustaining and preserving evidence of past life. In this regard, the interior layered deposits of Candor, Ophir, and Hebes Chasmas, have been identified as possible lucustrine sediments that may have been laid down in long-standing ice-covered lakes. The potential survival and growth of native organisms in such an environment, or in the aquifers whose disruption gave birth to the chaotic terrain and outflow channels to the north and east of the canyon, raises the possibility that fossil indicators of life may be present in the local sediment and rock. Because of the enormous distances over which these diverse environments occur, identifying a single landing site that maximizes the opportunity for scientific return is not a simple task. However, given the fluvial history and narrow geometry of the canyon, the presence of a single exit at its eastern end provides an opportunity for sampling that appears unequaled elsewhere in the system.

George, J. A.; Clifford, S. M.

1999-01-01

81

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

82

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

Microsoft Academic Search

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 mum, a strong, broad band centered near 1.94 mum, a sharp band at 2.23 mum, and

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

2008-01-01

83

Mars Reconnaissance Orbiter observations of light-toned layered deposits and associated fluvial landforms on the plateaus adjacent to Valles Marineris  

NASA Astrophysics Data System (ADS)

We have used data from the Mars Reconnaissance Orbiter to study 30-80 m thick light-toned layered deposits on the plateaus adjacent to Valles Marineris at five locations: (1) south of Ius Chasma, (2) south of western Melas Chasma, (3) south of western Candor Chasma, (4) west of Juventae Chasma, and (5) west of Ganges Chasma. The beds within these deposits have unique variations in brightness, color, mineralogy, and erosional properties that are not typically observed in light-toned layered deposits within Valles Marineris or many other equatorial areas on Mars. Reflectance spectra indicate these deposits contain opaline silica and Fe-sulfates, consistent with low-temperature, acidic aqueous alteration of basaltic materials. We have found valley or channel systems associated with the layered deposits at all five locations, and the volcanic plains adjacent to Juventae, Ius, and Ganges exhibit inverted channels composed of light-toned beds. Valleys, channels, and light-toned layering along the walls of Juventae and Melas Chasmata are most likely coeval to the aqueous activity that affected the adjacent plateaus and indicate some hydrological activity occurred after formation of the chasmata. Although the source of water and sediment remains uncertain, the strong correlation between fluvial landforms and light-toned layered deposits argues for sustained precipitation, surface runoff, and fluvial deposition occurring during the Hesperian on the plateaus adjacent to Valles Marineris and along portions of chasmata walls.

Weitz, C. M.; Milliken, R. E.; Grant, J. A.; McEwen, A. S.; Williams, R. M. E.; Bishop, J. L.; Thomson, B. J.

2010-01-01

84

Identification and spatial distribution of light-toned deposits enriched in Al-phyllosilicates on the plateaus around Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

The plateaus around Valles Marineris consist in series of mafic rocks suggested to be flood basalts (McEwen et al., 1998), lavas interbedded with sediments (Malin and Edgett, 2000), layered intrusive rocks (Williams et al., 2003), or lava flows dated from the Noachian to the late Hesperian epochs (Scott and Carr, 1978). Recent studies show the occurrence of light layered deposits of hundred meters thick cropping out on plateaus near Ius Chasma, Melas Chasma, Candor Chasma, Juventae Chasma and Ganges Chasma deposited during the Hesperian epoch by fluvio-lacustrine processes (Weitz et al., 2009), or by air-fall processes (Le Deit et al., 2009). These layered deposits are enriched in hydrated minerals including opaline silica (Milliken et al., 2008), hydroxylated ferric sulfates (Bishop et al., 2009), and possibly Al-rich phyllosilicates (Le Deit et al., 2009). We identified another type of formation corresponding to light-toned massive deposits cropping out around Valles Marineris. It appears that these light-toned deposits are associated to bright, rough, and highly cratered terrains, located beneath a dark and thin capping unit. Previous studies report the occurrence of phyllosilicates on few locations around Valles Marineris based on OMEGA data analyses (Gondet et al., 2007; Carter et al., 2009). The analysis of CRISM data show that the light-toned deposits are associated with spectra displaying absorption bands at 1.4 ?m, 1.9 ?m, and a narrow band at 2.2 ?m. These spectral characteristics are consistent with the presence of Al-rich phyllosilicates such as montmorillonite, or illite in the light-toned deposits. They constitute dozens of outcrops located on the plateaus south and east of Coprates Chasma and Capri Chasma, and west of Ganges Chasma. All outcrops investigated so far are present over Noachian terrains mapped as the unit Npl2 by Scott and Tanaka (1986), and Witbeck et al. (1991). These light-toned deposits could result from in situ aqueous alteration of Noachian basaltic plateaus during or after the Noachian epoch. We also identified Fe/Mg-rich phyllosilicates that are commonly found in the southern highland Noachian terrains (Mustard et al., 2008). They are located in central peaks, rims and ejecta of impact craters on plateaus, suggesting excavation of old buried layers. The deposits located around Valles Marineris are characterized by a wide variety of hydrated minerals that registered the evolution of the environmental conditions from the Noachian to the late Hesperian epochs. Further investigations are ongoing to determine their global spatial distribution and their stratigraphical relationships in order to better constrain the geological and climatic history of the region of Valles Marineris.

Le Deit, L.; Flahaut, J.; Quantin, C.; Allemand, P.

2009-12-01

85

Composition and structures of the subsurface in the vicinity of Valles Marineris as revealed by central uplifts of impact craters  

NASA Astrophysics Data System (ADS)

Despite recent efforts from space exploration to sound the martian subsurface with RADAR, the structure of the martian subsurface is still unknown. Major geologic contacts or discontinuities inside the martian crust have not been revealed. Another way to analyze the subsurface is to study rocks that have been exhumed from depth by impact processes. The last martian mission, MRO (Mars Reconnaissance Orbiter), put forth a great deal of effort in targeting the central peaks of impact craters with both of its high resolution instruments: CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) and HiRISE (High Resolution Science Experiment). We analyzed the composition with CRISM and the physical characteristics on HiRISE of the rocks exhumed from depth from 31 impact craters in the vicinity of Valles Marineris. Our analyses revealed the presence at depth of two kinds of material: massive light-toned rocks and intact layers. Exhumed light-toned massive rocks are enriched in low calcium pyroxenes and olivine. Hydrated phases such as smectites and putative serpentine are present and may provide evidence of hydrothermal processes. Some of the rocks may represent portions of the volatile-rich, pre-Noachian martian primitive crust. In the second class of central peaks, exhumed layers are deformed, folded, and fractured. Visible-near infrared (VNIR) spectra suggest that they are composed of a mixture of olivine and high calcium pyroxene associated with hydrated phases. These layers may represent a Noachian volcanic accumulation of up to 18 km due to Tharsis activity. The spatial distribution, as well as the in-depth distribution between the two groups of rocks exhumed, are not random and reveal a major geologic discontinuity below the Tharsis lava plateau. The contact may be vertical over several kilometers depth suggesting the pre-existence of a steep basin (early giant impact or subsidence basin) or sagduction processes.

Quantin, Cathy; Flahaut, Jessica; Clenet, Harold; Allemand, Pascal; Thomas, Pierre

2012-09-01

86

The Scale-height Of Optical-depth In Valles Marineris As Derived From Shadows In HRSC Images  

NASA Astrophysics Data System (ADS)

The optical depth of the Martian atmosphere can be estimated from the brightness of shadows with the so called "shadow method". We investigated the accuracy of this method by analyzing a set of stereo and color images observed on July 21, 2005 with the High Resolution Stereo Camera of the Mars-Express orbiter. The images show part of Valles Marineris during late afternoon and contain numerous shadows. Whereas the analyzed regions span height differences of about ten kilometers, we could study the relation between altitude and shadow method measurements. If the optical depth and gas-pressure have similar scale heights, then the accuracy with which our measurements can reproduce the pressure-scale-height tells about the accuracy of the shadow method. Various GCMs suggest a local pressure scale height of around 13 km at that moment, while the red and the five panchromatic stereo images all yielded similar scale heights with an average of 12.2 ± 0.7 km. Thus, in the color of the panchromatics (yellow to red) and in red the shadow method yielded good results. The scale height derived from the NIR image is too low: 10.6 ± 0.4 km, we speculate that this is an effect from airborne dust particles that are on average larger in the lower than in the higher atmosphere. The scale heights that were derived from blue and green images were unrealistically high: 17.0 ± 0.7 km and 14.5 ± 0.5 km respectively. This may be caused by thin white high altitude hazes, or indicate that the accuracy of the shadow method varies with optical depth in these colors.

Hoekzema, Nick; Garcia-Comas, M.; Petrova, E. V.; Stenzel, O. J.; Markiewicz, W. J.; Gwinner, K.; Keller, H. U.

2009-09-01

87

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

88

Study of phyllosilicates and carbonates from the Capri Chasma region of Valles Marineris on Mars based on Mars Reconnaissance Orbiter-Compact Reconnaissance Imaging Spectrometer for Mars (MRO-CRISM) observations  

NASA Astrophysics Data System (ADS)

Spectral reflectance data from the MRO-CRISM (Mars Reconnaissance Orbiter-Compact Reconnaissance Imaging Spectrometer for Mars) of Capri Chasma, a large canyon within Valles Marineris on Mars, have been studied. Results of this analysis reveal the presence of minerals, such as, phyllosilicates (illite, smectite (montmorillonite)) and carbonates (ankerite and manganocalcite). These minerals hint of the aqueous history of Noachian time on Mars. Phyllosilicates are products of chemical weathering of igneous rocks, whereas carbonates could have formed from local aqueous alteration of olivine and other igneous minerals. Four different locations within the Capri Chasma region were studied for spectral reflectance based mineral detection. The study area also shows the spectral signatures of iron-bearing minerals, e.g. olivine with carbonate, indicating partial weathering of parent rocks primarily rich in ferrous mineral. The present study shows that the minerals of Capri Chasma are characterized by the presence of prominent spectral absorption features at 2.31 ?m, 2.33 ?m, 2.22 ?m, 2.48 ?m and 2.52 ?m wavelength regions, indicating the existence of hydrous minerals, i.e., carbonates and phyllosilicates. The occurrence of carbonates and phyllosilicates in the study area suggests the presence of alkaline environment during the period of their formation. Results of the study are important to understand the formation processes of these mineral assemblages on Mars, which may help in understanding the evolutionary history of the planet.

Jain, Nirmala; Chauhan, Prakash

2015-04-01

89

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

90

Mineralogy of West Tithonium-Noctis Labyrinthus, Mars: Putative Volcanism on Noctis Canyons Floors  

NASA Astrophysics Data System (ADS)

A large number of pyroxene-rich areas are detected west of Valles Marineris with OMEGA spectral data. Most of them consist of sand dunes, but some rocky outcrops in the floor of Noctis could represent fresh lava flows formed inside the canyons.

Mangold, N.; Gendrin, A.; Gondet, B.; Le Mouélic, S.; Quantin, C.; Bibring, J.-P.; Langevin, Y.; Poulet, F.; Ansan, V.; Masson, Ph.; Hauber, E.; Neukum, G.

2008-03-01

91

Valles Marineris, Mars: High-Resolution Digital Terrain Model on the basis of Mars-Express HRSC data  

NASA Astrophysics Data System (ADS)

Introduction: Since December 2003, the European Space Agency's (ESA) Mars Express (MEX) orbiter has been investigating Mars. The High Resolution Stereo Camera (HRSC), one of the scientific experiments onboard MEX, is a pushbroom stereo color scanning instrument with nine line detectors, each equipped with 5176 CCD sensor elements. Five CCD lines operate with panchromatic filters and four lines with red, green, blue and infrared filters at different observation angles [1]. MEX has a highly elliptical near-polar orbit and reaches a distance of 270 km at periapsis. Ground resolution of image data predominantly varies with respect to spacecraft altitude and the chosen macro-pixel format. Usually, although not exclusively, the nadir channel provides full resolution of up to 10 m per pixel. Stereo-, photometry and color channels generally have a coarser resolution. One of the goals for MEX HRSC is to cover Mars globally in color and stereoscopically at high-resolution. So far, HRSC has covered almost half of the surface of Mars at a resolution better than 20 meters per pixel. Such data are utilized to derive high resolution digital terrain models (DTM), ortho-image mosaics and additionally higher-level 3D data products such as 3D views. Standardized high-resolution single-strip digital terrain models (using improved orientation data) have been derived at the German Aerospace Center (DLR) in Berlin-Adlershof [2]. Those datasets, i.e. high-resolution digital terrain models as well as ortho-image data, are distributed as Vicar image files (http://www-mipl.jpl.nasa.gov/external/vicar.html) via the HRSCview web-interface [3], accessible at http://hrscview.fu-berlin.de. A systematic processing workflow is described in detail in [4,5]. In consideration of the scientific interest, the processing of the Valles Marineris region will be discussed in this paper. The DTM mosaic was derived from 82 HRSC orbits at approximately -22° S to 1° N and 250° to 311° E. Methods: Apart from the DTM quality, image mosaicking also depends on the quality of exterior orientation data, and in order to generate high resolution DTMs and ortho-images, these data have to be corrected. For this purpose, new exterior and interior orientation data, based on tie-point matching and bundle adjustment have been used. The automated determination of tie points by software provided by the Leibniz Universität Hannover [6] are used as input in the bundle adjustment, provided by the Technische Universität München and Freie Universität Berlin. The bundle adjustment approach for photogrammetric point determination with a three-line camera is a least squares adjustment based on the well known collinearity equations. The approach estimates the parameters of the exterior orientation only at a few selected image lines. Because of Doppler shift measurements to estimate the position of the orbiter there are systematic effects in the observed exterior orientation. To model these effects in the bundle adjustment, additional observation equations for bias (offset) and drift have to be introduced. To use the MOLA DTM as control information, the least squares adjustment has to be extended with an additional observation equation for each HRSC point. These observations describe a relation between the MOLA DTM and these HRSC points. This approach is described in more detail in [7,8]. Derivation of DTMs and ortho-image mosaics are basically performed using software developed at the German Aerospace Center (DLR), Berlin and is using the Vicar environment developed at JPL. For the DTM derivation, the main processing tasks are first a prerectification of image data using the global MOLA-based DTM, then a least-squares area-based matching between nadir and the other channels (stereo and photometry) in a pyramidal approach and finally, DTM raster generation. Iterative low-pass image filtering (Gauss and mean filtering) is applied in order to improve the image matching process by increasing the amount and quality of object points and in order to reduce possible misdetections caused by i

Dumke, A.; Spiegel, M.; van Gasselt, S.; Neukum, G.

2009-04-01

92

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

93

Auqakuh Valles  

NASA Technical Reports Server (NTRS)

(Released 7 June 2002) The Science This ancient sinuous river channel, located near 30o N, 299o W (61o E), was likely carved by water early in Mars history. Auqakuh Valles cuts through a remarkable series of rock layers that were deposited and then subsequently eroded. This change from conditions favoring deposition to those favoring erosion indicates that the environment of this region has changed significantly over time. In addition, the different rock layers seen in this image vary in hardness, with some being relatively soft and easily eroded, whereas others are harder and resistant. These differences imply that these layers vary in their composition, physical properties, and/or degree of cementation, and again suggest that major changes have occurred during the history of this region. Similar differences occur throughout the southwest U.S., where hard rock layers, such as the limestones and sandstones in the Grand Canyon, form resistant cliffs, whereas softer mudstones are easily eroded to form broad slopes. The Martian layers, such as the smooth, dark-toned mesas visible in numerous places to the right (east) of the channel, were once continuous across the region. As these layers have eroded, they have produced a wide array of textures, from smooth surfaces, to knobby terrains, to the unusual lobate patterns seen in the upper right of the image. The most recent activity in the region appears to be the formation of mega-ripples by the wind. These ripples, spaced approximately 75 m apart, form perpendicular to the wind direction, and can be seen following the pattern of the channel floor as it curves through this region. This pattern shows that even this relatively small channel, which varies in width from about 500 to 750 m throughout this image, acts to funnel the wind down the channel. The Story Auqakuh Vallis, an ancient river channel that winds its way down the center of this image, is the 'fossil' remains of an earlier, probably more watery time in Martian history. Now, you might think that Auqakuh has something to do with Aqua, the Latin word for water. Instead, Auqakuh is the word for Mars in the Quechuan language of the Incan Empire that once stretched across vast portions of South America. This Inca-honoring river channel cuts through a remarkable series of rock layers that expose a history of climate change in the region. The coarse, rugged, and wildly textured terrain was created as rock layers were first deposited, then eroded over time. Some of the rock layers are soft and easily eroded, while others are clearly harder and more resistant. From these differences, geologists can tell that the layers are made up of different materials, have different physical characteristics, and are either loosely or strongly cemented together. That suggests major environmental changes over time as well, since different kinds of rocks form under different conditions. Similar differences in rock layers occur throughout the Southwest of the United States. The next time you're visiting the Grand Canyon or hiking in similar terrain, notice where hard rock layers, such as limestones and sandstones, form resistant cliffs, whereas softer mudstones are easily eroded to form broad slopes along the canyon. Just in case the river channel in the above image looks more like a raised vein rather than a hollowed out channel, try looking at the half-circle depression on the left-hand side of the image, about a third of the way up. The bright features on the upper half streak down toward the bottom of the bowl. Once you focus on this for a while, your brain figures out that the channel must be depressed as well. Now that you can see that the channel cuts into the surface, click on the image for a closer look at the bottom of the channel. Mega-ripples about 82 yards apart line the channel floor as it curves through the region. This pattern shows that even this relatively small channel, which varies from about one-third to a half of a mile in width, funnels the wind down its curving length, creating per

2002-01-01

94

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

95

Submarine canyons  

Microsoft Academic Search

This article discusses the nature and origin of submarine canyons, both the deep canyons crossing the continental slope and their shallower continuation seaward as fan-valleys. The canyons and sediments they contain are discussed in relation to the adjacent land and to the continental rise. Possible origins, including turbidity currents and upbuilding of the continental walls, are dealt with in the

F. P. Shepard

1972-01-01

96

Geologic Evidence for Late-Stage Equatorial Surface and Ground Ice on Mars  

Microsoft Academic Search

New imagery data from the Mars Observer Camera suggest that the equatorial canyon of Valles Marineris contained surface and ground ice relatively late in Martian history. Some troughs (or chasmata) of Valles Marineris contain large mounds and mesas of interior layered deposits (ILDs) that formed in the Late Hesperian to Early Amazonian. Although the origin of the ILDs remains controversial,

M. G. Chapman

2003-01-01

97

GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/, New insights on the runout of large landslides in the  

E-print Network

landslides in the Valles-Marineris Canyons, Mars E. Lajeunesse,1 C. Quantin,2 P. Allemand,2 and C. Delacourt2 of Valles- Marineris (VM) landslides can be scaled on a curve varying primarily with the initial aspect is not an appropriate tool to characterize VM landslides dynamics. 1. Introduction Since the first pictures returned

Delacourt, Christophe

98

ASTR/GEOL 5800 Planetary Surfaces & Interiors 7 November 2013  

E-print Network

on the U.S., the canyon would stretch from San Francisco to New York City. · 8 km deep in places #12;Valles magnetization #12;What do the crater populations tell you?? #12;The Grand Canyon of Mars · Valles Marineris ­ the largest canyon in the solar system ­ Formed from extensional stresses related to Tharsis ­ If laid

Mojzsis, Stephen J.

99

Warrego Valles  

NASA Technical Reports Server (NTRS)

3 October 2004 When viewed at 100 to 300 meters per pixel in old Mariner 9 and Viking orbiter images, Warrego Valles appears to be a grouping of intricately-carved networks of branching valleys. This region has often been used as the type example of martian valley networks, and key evidence that Mars may have once been warmer, wetter, and perhaps had precipitation in the form of rain or snow. However, when viewed at very high resolution (1.5 to 4.5 meters per pixel) with the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), the Warrego valleys break down into a series of vaguely continuous (in other words, not necessarily connected to each other) troughs that have been covered and partially filled by a material that has eroded to form a very rough-textured surface. None of the original valley floor or wall features are visible because of this rough-textured mantle, and thus very little can be said regarding whether the valleys represent the results of persistent flow and precipitation runoff. Despite the MOC observations and the relatively unique nature of these valleys relative to other valley networks on Mars, the Warrego Valles continue to be used by many as an example of typical martian valley networks. The picture shown here is a mosaic of three MOC narrow angle images obtained in 1999 and 2004: M07-02071, R15-00492, and R15-02626. The dark bar near the bottom center is the location of a data drop, lost during transmission. The 1 km scale bar is approximately equal to 0.62 miles. Sunlight illuminates the images from the upper left, north is up, and the scene is located near 42.4oS, 93.5oW.

2004-01-01

100

Grand Canyon  

... (lower) half of the images, other landmarks include Lake Powell, on the left, and Humphreys Peak and Sunset Crater National Monument on ... December 31, 2000 - Grand Canyon and Lake Powell. project:  MISR category:  gallery ...

2014-05-15

101

Mineralogy of Noctis Labyrinthus on the Basis of OMEGA/MEX and PFS/MEX Data  

NASA Astrophysics Data System (ADS)

The OMEGA/MEx and PFS/MEx data have been used to study the diversification of the mineral composition of the Noctis Labyrinthus region, which is situated in the western end of the Valles Marineris canyon on Mars.

Gurgurewicz, J.

2009-03-01

102

4. B. Asfaw et al., Nature 416, 317 (2002). 5. E. Abbate et al., Nature 393, 458 (1998).  

E-print Network

for support. The analysis and manuscript benefited from discussions with S. Anto´n, F. Spoor, and B. Wood Allemand2 Dendritic valleys on the plateau and canyons of the Valles Marineris region were identified from

Delacourt, Christophe

103

Hot Canyon  

ScienceCinema

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

2013-03-01

104

Small, Spectrally Distinct Deposits in the Valles Marineris, Mars: A New Lithology?  

Microsoft Academic Search

Materials suspected of having a relatively felsic spectral character were identified in THEMIS infrared data of Eos Chasma by Hamilton and Christensen [1]. A survey of decorrelation stretched THEMIS infrared images over Eos and Ganges Chasmata reveals that similar materials are widespread throughout the region, but do not form large outcrops; rather they most commonly are associated with small knobs

V. E. Hamilton

2005-01-01

105

Small, Spectrally Distinct Deposits in the Valles Marineris, Mars: A New Lithology?  

NASA Astrophysics Data System (ADS)

Materials suspected of having a relatively felsic spectral character were identified in THEMIS infrared data of Eos Chasma by Hamilton and Christensen [1]. A survey of decorrelation stretched THEMIS infrared images over Eos and Ganges Chasmata reveals that similar materials are widespread throughout the region, but do not form large outcrops; rather they most commonly are associated with small knobs in the vicinity of olivine-rich materials. Ratios of THEMIS spectra from olivine-rich materials to Eos Chasma floor materials show an expected long wavelength absorption characteristic of olivine enrichment. Spectral ratios of the newly identified material to the floor materials, on the other hand, show an unusual shape dominated by a short wavelength absorption characteristic of felsic minerals, although this assignment is tentative. We are analyzing THEMIS and TES atmosphere-subtracted surface spectra to determine the phase(s) responsible for the observed signatures. This presentation will describe the mineralogy, morphology and thermophysical properties of these materials as observed by THEMIS and TES, as well as related characteristics observed in MOC and MOLA data. [1] Hamilton, V. E., and P. R. Christensen (2003), Eos Trans. AGU, 84, Fall Meet. Suppl., Abstract P21A-03.

Hamilton, V. E.

2005-12-01

106

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

E-print Network

flanks pre- dicted by models of normal faulting [1]. This uplift is obscured in the east and west that the depths of the troughs was controlled by isostatic balance with the sedimentary infill, with the troughs to the removal of these sediments. Methods: We used a thin-shell, elastic litho- spheric loading model [7, 8

107

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

108

Marte Valles site  

NASA Technical Reports Server (NTRS)

This site is located at 16 deg N, 177 deg W on the flood plains of Marte Valles, which is perhaps the youngest channel system on Mars. The young age of this channel warrants investigation because of climatic implications for fluvial activities in recent geologic time. The paucity of craters makes this an excellent site in terms of safety requirements. Some of the objectives stated previously for the Maja Valles region would also apply to this site (grab bag of rock types, etc.).

Rice, Jim W.

1994-01-01

109

Mapping the Canyon  

NSDL National Science Digital Library

In this activity, students will learn about the bathymetry of Hudson Canyon, a submarine canyon on the Atlantic coast of North America. As they study Hudson Canyon, they will compare and contrast topographic maps and bathymetric maps, investigate the various ways in which bathymetric maps are made, and learn how to interpret bathymetric maps.

110

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

111

Bryce Canyon Hoodoo  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

112

Hoodoos of Bryce Canyon  

USGS Multimedia Gallery

Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

113

Bryce Canyon Hoodoos  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

114

Bryce Canyon Hoodoos  

USGS Multimedia Gallery

Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

115

Bryce Canyon's Cedar Valley  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

116

Bryce Canyon Sandstone  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

117

Bryce Canyon Cedars  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

118

Bryce Canyon Vistas  

USGS Multimedia Gallery

Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

119

Bryce Canyon Hoodoo  

USGS Multimedia Gallery

Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

120

Bryce Canyon Benchmark  

USGS Multimedia Gallery

A USGS elevation benchmark in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that ...

121

Bryce Canyon Rim  

USGS Multimedia Gallery

The rim of Bryce Canyon, viewed from Rainbow Point. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms ...

122

Bryce Canyon Amphitheater  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

123

Bryce Canyon Amphitheater Panorama  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

124

Bryce Canyon Amphitheater  

USGS Multimedia Gallery

Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

125

Bryce Canyon Amphitheater Hoodoos  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

126

Bryce Canyon Natural Bridge  

USGS Multimedia Gallery

The Bryce Canyon Natural Bridge. Technically, this is not a natural bridge, which forms when running water erodes a tunnel into a rock formation. Instead, this is a natural arch, similar to the ones in nearby Arches National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is...

127

Bryce Canyon Natural Bridge  

USGS Multimedia Gallery

Bryce Canyon's Natural Bridge is technically a natural arch, similar to those in the nearby Arches National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates...

128

Glen Canyon Dam  

USGS Multimedia Gallery

The USGS Glen Canyon Adaptive Management Working Group took a trip in August from Glen Canyon Dam to Lees Ferry on Friday, August 31, 2012. This spot at Four Mile (four miles downstream from the dam) is where a lot of people fish: There were fishermen that day that claimed to have c...

129

Bryce Canyon Hoodoos  

USGS Multimedia Gallery

Sandstone hoodoos in Bryce Canyon National Park. In the background, Grand Staircase-Escalante National Monument can be seen. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different er...

130

Hoodoos of Bryce Canyon  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

131

Snake Hells Canyon Subbasin Inventory  

E-print Network

Snake Hells Canyon Subbasin Inventory May 2004 Prepared for the Northwest Power and Conservation .................................................................................................................................. 62 8 APPENDIX A APRE SUMMARIES FOR HELLS CANYON SUBBASIN.................. 63 Snake Hells Canyon Subbasin Inventory i May 2004 #12;LIST OF FIGURES FIGURE 1.LAND MANAGEMENT IN THE SNAKE HELLS CANYON

132

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

133

Hydrated Minerals Associated with Interior Layered Deposits near the Southern Wall of Melas Chasma, Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

MRO CRISM full resolution targeted mode hyperspectral image data (FRT00013F5B) centered at 10.22 S, 74.46 W over a portion of the southern wall and nearby floor of Melas Chasma show a sequence of interior layered deposits with distinct mineral associations. This study area is located to the southeast of the region analyzed by Roach et al. (2010, Icarus, 206, 253-268). The topography associated the deposits was examined using standard product elevation maps derived from HRSC data and used along with superposition relationships to help define the stratigraphic order. The bottom of the exposed section consists of repeating interbedded monohydrated and polyhydrated sulfate-bearing layers. Jarosite-bearing layers are found above this sequence, along with layers that have a 2.3 micrometer absorption tentatively identified as due to Fe/Mg smectite-bearing material. The top of the section is dominated by an areally extensive polyhydrated sulfate-bearing unit. Detailed results will be presented along with an analysis of the changing aqueous conditions inferred from the mineral associations.

Liu, Y.; Arvidson, R. E.

2011-12-01

134

A structural study of an interior layered deposit in southwestern Candor Chasma, Valles Marineris, Mars, using high resolution stereo  

E-print Network

by the High Resolution Stereo Camera (HRSC) of the Mars Express mission which enable the derivation of digital, Mars, using high resolution stereo camera data from Mars Express F. Fueten,1 R. Stesky,2 P. MacKinnon,1 Resolution Stereo Camera of the Mars Express mission. Most ILD layers dip in the same direction

Utrecht, Universiteit

135

Valles Marineris, Mars: High-Resolution Digital Terrain Model on the basis of Mars-Express HRSC data  

Microsoft Academic Search

Introduction: Since December 2003, the European Space Agency's (ESA) Mars Express (MEX) orbiter has been investigating Mars. The High Resolution Stereo Camera (HRSC), one of the scientific experiments onboard MEX, is a pushbroom stereo color scanning instrument with nine line detectors, each equipped with 5176 CCD sensor elements. Five CCD lines operate with panchromatic filters and four lines with red,

A. Dumke; M. Spiegel; S. van Gasselt; G. Neukum

2009-01-01

136

The Grand Canyon  

NSDL National Science Digital Library

The first site from PBS.org, called Lost in the Canyon (1), offers an excellent online learning experience. Visitors learn about John Wesley Powell's expedition down the Colorado River, covered in transcripts from the companion television show and a timeline of Powell's life. Other features include an interactive lesson on running rapids and a look at the unique geologic history of the area. Next, from StudyWorks! Online comes the lesson entitled Sleuthing at the Grand Canyon: Using Rocks to Tell Us About the Past (2). Through basic descriptions, photographs, and illustrations, students learn how rocks form, how scientists use them to find out about past environments, and much more. The third site is provided by the Grand Canyon Monitoring and Research Center called The Grand Canyon Monitoring and Research Center Fiscal Year 2000-2004 Monitoring and Research Strategic Plan (3). Readers will discover the mission of the center, history of monitoring in the area, management strategies, research activities, and much more. Next is a site offered by Richard S. Naylor of Northeastern University's Department of Geology called Unconformities in the Grand Canyon (4). Visitors will find descriptions and photographs of several sites in the Grand Canyon that exhibit geologic unconformities or surfaces that represent a break in the geologic record. The fifth site is maintained by kaibob.org called the Geology of Grand Canyon (5). This site contains basic information on how the canyon was formed, where all the rock came from, why it looks like it does, and when it all happened. From NASA's Visible Earth Web site comes the 3-D View of Grand Canyon (6) page. The canyon can be viewed in a low or high resolution JPEG format, which shows the surrounding area, part of the Colorado river, and the canyon itself in dynamic colors. Part of Northern Arizona University, the seventh site is entitled Canyons, Culture, and Environmental Change: An Introduction to the Land Use History of the Colorado Plateau (7). The site provides an introduction to the environmental history of the Colorado Plateau and summarizes a vast body of research from multiple disciplines in an easily accessible format. The last site from NOAA's Colorado River Basin Forecast Center is the River Forecasts and Data page (8). Provided are data from various sites along the river that offer a wide range of relevant information such as simulated hydrographs.

Brieske, Joel A.

2002-01-01

137

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

138

Constraints on the Martian cratering rate imposed by the SNC meteorites and Vallis Marineris layered deposits  

NASA Technical Reports Server (NTRS)

Following two independent lines of evidence -- estimates of the age and formation time of a portion of the Martian geologic column exposed in the layered deposits and the crystallization and ejection ages of the SNC meteorites -- it appears that the Martian cratering rate must be double the lunar rate or even higher. This means models such as NHII or NHIII (Neukum and Hiller models II and III), which estimate the Martian cratering rate as being several times lunar are probably far closer to reality on Mars than lunar rates. The effect of such a shift is profound: Mars is transformed from a rather Moon-like place into a planet with vigorous dynamics, multiple large impacts, erosion, floods, and volcanism throughout its history. A strong shift upward in cratering rates on Mars apparently solves some glaring problems; however, it creates others. The period of time during which Earth-like atmospheric conditions existed, the liquid water era on Mars, persists in NHIII up to only 0.5 b.y. ago. Scenarios of extended Earth-like conditions on Mars have been discounted in the past because they would have removed many of the craters from the early bombardment era found in the south. It does appear that some process of crater removal was quite vigorous in the north during Mars' past. Evidence exists that the northern plains may have been the home of long-lived seas or perhaps even a paleo-ocean, so models exist for highly localized destruction of craters in the north. However, the question of how the ancient crater population could be preserved in the south under a long liquid-water era found in any high-cratering-rate models is a serious question that must be addressed. It does appear to be a higher-order problem because it involves low-energy dynamics acting in localized areas, i.e., erosion of craters in the south of Mars, whereas the two problems with the low-cratering-rate models involve high-energy events acting over large areas: the formation of the Vallis Marineris, the SNC ejecting impacts, and the global atmospheric pressure and temperature conditions that allow liquid water to exist as a robust entity anywhere on the Martian surface. In any case, it appears Mars is a more complex and dynamic planet than previously supposed. It has canyons dating from the middle to late period of its history that contain apparent lake sediments bedded deeper than most sediments on Earth. Recent multiple, violent impacts on Mars have apparently provided us with multiple random samples of its surface that all crystallized less than 1.5 b.y. ago. These things cannot be accommodated in our present cratering chronologies of Mars, based on 1x lunar cratering rates, without great difficulties. These difficulties suggest that a new chronology, probably based on NHII or even NHIII, should be adopted; this new chronology will provide us with a new view of Mars as a dynamic planet of rich history.

Brandenburg, J. E.

1993-01-01

139

The canyon hypothesis.  

PubMed

The three-dimensional structure of human rhinovirus 14 has a deep surface depression or "canyon" encircling each of the twelve fivefold vertices. The canyon's surface is inaccessible to the broad antigen binding region of antibodies, permitting conservation of residues that might be required for host cell receptor recognition without danger of attack by the host's immune system. In contrast, the exposed surface features, where neutralizing antibodies are known to bind, change rapidly under pressure from the host's immune system. It was, therefore, hypothesized that this depression was the site of receptor attachment. Similar, but smaller, depressions had been observed previously on both the hemagglutinin and neuraminidase spikes of influenza virus. These have also been shown to be the site of host cell interaction. Although support for the canyon hypothesis was only circumstantial in the first place, there are now extensive confirmatory data. These include site-specific mutations of residues in the canyon and conformational changes induced in the canyon by the binding of small organic molecules, all of which alter receptor attachment. The strategy used in human rhinovirus 14 to protect the viral receptor attachment site from immune surveillance may be utilized not only in other picornaviruses but also in many other types of viruses including human immunodeficiency virus. PMID:2560913

Rossmann, M G

1989-01-01

140

Landslide in Kasei Valles  

NASA Technical Reports Server (NTRS)

The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) continues in 2003 to return excellent, high resolution images of the red planet's surface. This nearly 1.5 meters (5 ft.) per pixel view of a landslide on a 200 meter-high (219 yards-high) slope in Kasei Valles was specifically targeted for scientific investigation by rotating the MGS spacecraft about 7.8o off-nadir in January 2003. The scar left by the landslide reveals layers in the bedrock at the top the slope and shows a plethora of dark-toned, house-sized boulders that rolled down the slope and collected at the base of the landslide scar. A few meteor impact craters have formed on the landslide deposit and within the scar, indicating that this landslide occurred a very long time ago. Sunlight illuminates this scene from the left/lower left; the landslide is located near 28.3oN, 71.9oW.

2003-01-01

141

FINAL REPORT CANYON AND SLOPE  

E-print Network

fisheries. Many of these canyons provide habitats for a variety of deep water corals . They have also been#12;FINAL REPORT CANYON AND SLOPE PROCESSES STUDY VOLUME I EXECUTIVE S(2@lARY Prepared for United . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...11 #12;Introduction The eastern U.S. continental margin is incised by numerous submarine canyons

Mathis, Wayne N.

142

Snake Hells Canyon Subbasin Assessment  

E-print Network

Snake Hells Canyon Subbasin Assessment May 2004 Prepared for the Northwest Power and Conservation, Ecovista Angela Sondenaa, Nez Perce Tribe Darin Saul, Ecovista #12;Snake Hells Canyon Subbasin Assessment Table of Contents 0 INTRODUCTION TO SNAKE HELLS CANYON SUBBASIN ASSESSMENT............ 1 1 SUBBASIN

143

Isotopic and geochemical constraints on the origin and evolution of postcollapse rhyolites in the Valles Caldera, New Mexico  

Microsoft Academic Search

Ring-fracture rhyolites of the Valles Caldera (VC) were examined to determine the evolution of the magma system following eruption of the upper Bandelier Tuff (UBT) and subsequent caldera collapse. Volcanism began with eruption of Deer Canyon (DC), Redondo Creek, and Del Medio (DM) rhyolites during the interval 1140-1133 ka. Quartz delta O-18 for the UBT, (average +8.3 %), DC (+7.9

Terry L. Spell; Philip R. Kyle; Matthew F. Thirlwall; Andrew R. Campbell

1993-01-01

144

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

145

Glen Canyon Dam  

USGS Multimedia Gallery

The Glen Canyon Dam on the Colorado River in Arizona. At noon Monday, Nov. 19, U.S. Interior Secretary Ken Salazar will open the dam’s river outlet tubes, releasing controlled flows larger than the usual 8,000-25,000 cubic feet per second that flows through the turbines of the Glen...

146

Homogenizing Coastal Canyons  

Microsoft Academic Search

We consider coastal waves that are weakly nonlinear due to rapid bottom variations along the coast and, in particular, due to the presence of a series of deep canyons on the shelf break with their crests lying perpendicular to the coast. In addition, the bottom topography may vary slowly in both horizontal coordinates. Starting with the rigid lid shallow water

O. Bokhove

2002-01-01

147

Downstream in Mawrth Valles  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

The THEMIS VIS camera is capable of capturing color images of the Martian surface using five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from using multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

This false color image is from further downstream in Mawrth Valles than yesterday's image. The channel here is at the end of the vallis. This image was collected during the Northern Spring season.

Image information: VIS instrument. Latitude 26.7, Longitude 340.2 East (19.8 West). 37 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

148

Sedimentary facies in submarine canyons  

NASA Astrophysics Data System (ADS)

Submarine canyons are the major conduits by which sediment, pollutants and nutrients are transported from the continental shelf out into the deep sea. The sedimentary facies within these canyons are remarkably poorly understood because it has proven difficult to accurately sample these heterogeneous and bathymetrically complex environments using traditional ship-based coring techniques. This study exploits a suite of over 100 precisely located vibracores collected using remotely operated vehicles in ten canyons along the northern Californian margin, enabling better understanding of the facies that exist within submarine canyons, their distribution, and the processes responsible for their formation. The dataset reveals three major facies types within the submarine canyons: extremely poorly sorted, coarse-grained sands and gravels with complex and indistinct internal grading patterns and abundant floating clasts; classical normally graded thin bedded turbidites; and a variety of fine-grained muddy deposits. Not all facies are observed within individual canyons, in particular coarse-grained deposits occur exclusively in canyons where the canyon head cuts up to the modern day beach, whereas finer grained deposits have a more complex distribution that relates to processes of sediment redistribution on the shelf. Pairs of cores collected within 30 meters elevation of one another reveal that the coarse-grained chaotic deposits are restricted to the basal canyon floor, with finer-grained deposits at higher elevations on the canyon walls. The remarkable heterogeneity of the facies within these sediment cores illustrate that distinctive processes operate locally within the canyon. In the authors' experience the canyon floor facies represent an unusual facies rarely observed in ancient outcrops, which potentially results from the poor preservation of ancient coarse-grained canyon deposits in the geological record.

Sumner, E.; Paull, C. K.; Gwiazda, R.; Anderson, K.; Lundsten, E. M.; McGann, M.

2013-12-01

149

The Nearshore Canyon Experiment  

NASA Astrophysics Data System (ADS)

Observations collected in Fall 2003 during the Nearshore Canyon Experiment (NCEX) will be used to test hypotheses about the effect of complex continental-shelf bathymetry on surface gravity waves and on wave-driven circulation. Refraction, diffraction, reflection, scattering, and trapping by abrupt shelf bathymetry can result in dramatic alongshore variations in wave height and direction. Onshore of the irregular bathymetry, alongcoast changes in breaking waves can force complicated circulation, including alongshore flows that reverse direction across the surf zone and along the shoreline, and strong offshore-directed rip currents that may be an important mechanism for transport of water, sediment, and pollution between the surf zone and inner shelf. Observations for NCEX will be obtained along the southern California coast near two steep submarine canyons (separated alongshore by a few km) that cross the shelf from about 300-m water depth to just seaward of the surfzone near Black's Beach (famous for large waves) and La Jolla Shores (well known as a calm area with small waves). Frequency-directional spectra of incident waves estimated from observations offshore of the canyons will be used to initialize models that predict the effect of the canyons on infragravity waves, swell, sea, and wave-driven circulation. Model predictions will be tested with observations from alongshore arrays deployed near, between, and onshore (including the surf and swash zones) of the canyons. Arrays also will be deployed to investigate wave reflection and scattering from the steep canyon walls, and cross-shore changes in surf and swash zone circulation. Additional instrumentation will be used to study alongcoast changes in wave breaking and set-up, details of surface currents in the surf and swash, and breaking-induced turbulence and dissipation. The NCEX instrument arrays will be designed in collaboration with modelers, and near-real time data will be used to initialize and test model predictions. In addition, model forecasts will be used to guide placement of movable sensors, allowing predictions of nearshore waves and currents to be tested during the observational period. NCEX~team~members~are~listed~on http://science.whoi.edu/PVLAB/NCEX/ncex.html. Funding for NCEX is provided by the US Office of Naval Research and the National Science Foundation.

Elgar, S.

2002-12-01

150

The Target  

NASA Technical Reports Server (NTRS)

This mosaic of Mars is a compilation of images captured by the Viking Orbiter 1. The center of the scene shows the entire Valles Marineris canyon system, over 3,000 km long and up to 8 km deep, extending from Noctis Labyrinthus, the arcuate system of graben to the west, to the chaotic terrain to the east.

2003-01-01

151

The Grand Canyon  

NSDL National Science Digital Library

This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. It focuses on the ecology of the Grand Canyon area. Students act as scientists investigating the damming of the Colorado River by the Glen Canyon dam and experimental flooding that took place in 1996. They then write a proposal as to whether or not more experimental flooding should be done on the area considering the ecological effects. It includes objectives, materials, procedures, discussion questions, evaluation ideas, extensions, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

152

Flushing submarine canyons  

Microsoft Academic Search

The continental slope is a steep, narrow fringe separating the coastal zone from the deep ocean. During low sea-level stands, slides and dense, sediment-laden flows erode the outer continental shelf and the continental slope, leading to the formation of submarine canyons that funnel large volumes of sediment and organic matter from shallow regions to the deep ocean1. During high sea-level

Miquel Canals; Pere Puig; Xavier Durrieu de Madron; Serge Heussner; Albert Palanques; Joan Fabres

2006-01-01

153

Flushing submarine canyons.  

PubMed

The continental slope is a steep, narrow fringe separating the coastal zone from the deep ocean. During low sea-level stands, slides and dense, sediment-laden flows erode the outer continental shelf and the continental slope, leading to the formation of submarine canyons that funnel large volumes of sediment and organic matter from shallow regions to the deep ocean(1). During high sea-level stands, such as at present, these canyons still experience occasional sediment gravity flows(2-5), which are usually thought to be triggered by sediment failure or river flooding. Here we present observations from a submarine canyon on the Gulf of Lions margin, in the northwest Mediterranean Sea, that demonstrate that these flows can also be triggered by dense shelf water cascading (DSWC)-a type of current that is driven solely by seawater density contrast. Our results show that DSWC can transport large amounts of water and sediment, reshape submarine canyon floors and rapidly affect the deep-sea environment. This cascading is seasonal, resulting from the formation of dense water by cooling and/or evaporation, and occurs on both high- and low-latitude continental margins(6-8). DSWC may therefore transport large amounts of sediment and organic matter to the deep ocean. Furthermore, changes in the frequency and intensity of DSWC driven by future climate change may have a significant impact on the supply of organic matter to deep-sea ecosystems and on the amount of carbon stored on continental margins and in ocean basins. PMID:17108962

Canals, Miquel; Puig, Pere; de Madron, Xavier Durrieu; Heussner, Serge; Palanques, Albert; Fabres, Joan

2006-11-16

154

Ancient Observatories: Chaco Canyon  

NSDL National Science Digital Library

Located in the northwest corner of New Mexico, Chaco Canyon is a shallow, ten-mile canyon accessible only by washboard dirt roads. It is an area of tremendous cultural importance, as it was once the center of an elaborate system of buildings, roadways, and other construction. Intense building activity continued at the site until about AD 1150, and then it was quickly abandoned. Today, it is a National Historic Park and a UNESCO World Heritage Site. On this site created by the Exploratorium in San Francisco, visitors can learn about this unique place via sections that provide insight into its layout, its history of human habitation, and also its various celestial alignments. First-time visitors can click on the Sense of Place tab to view a time-lapse video of the site. The Time area is remarkable, as visitors can read an essay titled "How Old Is It?" and then watch "Migration Stories," which talks about the experiences that humans have had there over the centuries. The site is rounded out by the Observation area, which allows users to learn about how the canyon's unique qualities have fascinated visitors, explorers, and others.

155

Yucca in Pine Creek Canyon  

USGS Multimedia Gallery

Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

156

Chollas in Pine Creek Canyon  

USGS Multimedia Gallery

The Mojave Desert, home to drought-tolerant plants like Cholla cacti, gradually mixes with loblolly pine ecosystems in Pine Creek Canyon. Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Roc...

157

Yuccas in Pine Creek Canyon  

USGS Multimedia Gallery

The Mojave Desert, home to drought-tolerant plants like yuccas, gradually mixes with loblolly pine ecosystems in Pine Creek Canyon. Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Cany...

158

Manzanita in Pine Creek Canyon  

USGS Multimedia Gallery

Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

159

Rainbow Point of Bryce Canyon  

USGS Multimedia Gallery

View of Bryce Canyon National Park from Rainbow Point. In the foreground are sandstone hoodoos. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite ...

160

Bryce Canyon's Navajo Loop Trail  

USGS Multimedia Gallery

Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

161

Cedar Forest in Bryce Canyon  

USGS Multimedia Gallery

A cedar forest in Bryce Canyon National Park, viewed from Rainbow Point. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the ...

162

Cedar Forests of Bryce Canyon  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

163

Cedar Valley in Bryce Canyon  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

164

Snow-covered Bryce Canyon  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

165

Sunset in Pine Creek Canyon  

USGS Multimedia Gallery

Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

166

Sunset over Pine Creek Canyon  

USGS Multimedia Gallery

Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

167

Sunset over Red Rock Canyon  

USGS Multimedia Gallery

Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

168

Cedar Tree in Bryce Canyon  

USGS Multimedia Gallery

A cedar tree in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their ba...

169

Bryce Canyon Wall of Windows  

USGS Multimedia Gallery

Bryce Canyon's Wall of Windows, a series of sandstone arches and hoodoos in the Bryce Amphitheater. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolom...

170

Bryce Canyon's Wall of Windows  

USGS Multimedia Gallery

Bryce Canyon's Wall of Windows, a series of sandstone arches and hoodoos in the Bryce Amphitheater. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolom...

171

Rainbow Point of Bryce Canyon  

USGS Multimedia Gallery

View of Bryce Canyon National Park from Rainbow Point. In the foreground are sandstone hoodoos and in the background is the Grand Staircase-Escalante National Monument, which is managed by the Bureau of Land Management. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a ...

172

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

USGS Publications Warehouse

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

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

2006-01-01

173

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

174

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

175

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

176

Grand Canyon: The Hidden Secrets  

NSDL National Science Digital Library

Summertime means vacations for many people, and for many of these sojourning to the American Southwest, this may mean a trip to the brilliance that is the Grand Canyon in northern Arizona. The people at National Geographic certainly know this area quite well, as they have sponsored a number of research expeditions there over the past century or so. Designed as a way to publicize the film that the organization plays at their canyon visitor center, this site contains a number of helpful features for those persons who may be visiting the canyon. First, visitors will want to look at the interactive map of the South Rim offered here. The map allows visitors to learn about selected features of the area, such as the famous bald eagles, the various outlooks, and the plants indigenous to the region. The site also includes a section for young people, a number of free screensavers and wallpapers, along with a travel guide to visiting the Grand Canyon.

177

Canyon waste dump case study  

SciTech Connect

This data packet contains the Canyonville Canyon Waste Dump results of the various physical environmental sampling. Core samples were taken from the on site waste material. Vertical grab samples were made from these borings. The waste samples were screened fro volatile organic compounds (VOC) and logged for lithology. Soil samples were also tested for VOC. Composite sediment samples were taken using a coring device known as a clam gun. No surface water was available for testing from the intermittent Canyon Wash. The hydrogeology of the Canyon Waste Dump was inferred from lithologic logs and hydraulic data from the five monitoring wells located along the canyon floor. Groundwater was monitored through five wells. The soil vapor and air screening techniques used were adaptations of the EPA ERT and NIOSH methodologies. 4 figs., 9 tabs.

Land, M.D.; Brothers, R.R. (Tennessee Univ., Knoxville, TN (United States)); McGinn, C.W. (Oak Ridge National Lab., TN (United States))

1991-01-01

178

Duration and rates of discharge - Maja Valles, Mars  

NASA Astrophysics Data System (ADS)

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.

de Hon, R. A.; Pani, E. A.

1993-05-01

179

Snake Hells Canyon Subbasin Management Plan  

E-print Network

Snake Hells Canyon Subbasin Management Plan May 2004 Prepared for the Northwest Power and Conservation Council Subbasin Team Leader Nez Perce Tribe Watershed Division Written by Ecovista #12;Snake...............................................................................8 4 VISION FOR THE SNAKE HELLS CANYON SUBBASIN

180

Geology Fieldnotes: Grand Canyon National Park, Arizona  

NSDL National Science Digital Library

Visitors can access park geology information, photographs, related links, visitor information, multimedia resources, and resources for teaching geology with National Park examples. The park geology section discusses the Grand Canyon's geologic history, structural geology, and features a question-and-answer section about the canyon. The history of the canyon as a park and environmental issues surrounding it are also discussed. A geologic cross section of the canyon showing the various rock layers is included.

181

Currents in monterey submarine canyon  

USGS Publications Warehouse

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

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

2009-01-01

182

Stratigraphy of the Kasei Valles region, Mars  

NASA Technical Reports Server (NTRS)

The thicknesses and geomorphology of the two principal stratigraphic units exposed in Kasei Valles to aid in interpreting the nature of crustal materials and the history of the channeling events in the area are identified and described. Previous studies of Kasei Valles have related the channel landforms to glacial flow, catastrophic flooding, and large-scale eolian erosion. The two units (an upper and a lower unit) form thick sheets, each having distinct geomorphologic features. Thicknesses of the unit were determined through preliminary stereogrammetric profiles taken across many sections of western Kasei Valles and shadow measurements taken of scarp heights from calibrated Viking images having sun angles less than 25 degrees; DN values were examined to confirm that true shadows were observed.

Robinson, Mark S.; Tanaka, Kenneth L.

1987-01-01

183

Tubes at Glen Canyon Dam  

USGS Multimedia Gallery

The river outlet tubes at Glen Canyon Dam on the Colorado River in Arizona. At noon Monday, Nov. 19, U.S. Interior Secretary Ken Salazar will open the dam's river outlet tubes, releasing controlled flows larger than the usual 8,000-25,000 cubic feet per second that flows through the turbines of...

184

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

185

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

186

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

187

Mineral resources of the Coal Canyon, Spruce Canyon, and Flume Canyon Wilderness Study Areas, Grand county, Utah  

SciTech Connect

This paper reports on the Coal Canyon, Spruce Canyon, and Flume Canyon Wilderness Study Areas in the Book and Roan Cliffs in Grand Country, Utah, approximately 12 miles west of the Colorado state line. The wilderness study areas consist of a series of deep, stair-step-sided canyons and high ridges eroded into the flatlying sedimentary rocks of the Book Cliffs. Demonstrated coal reserves totaling 22,060,800 short tons and demonstrated subeconomic coal resources totaling 39,180,000 short tons are in the Coal Canyon Wilderness Study Area. Also, inferred subeconomic coal resources totaling 143,954,000 short tons are within the Coal Canyon Wilderness Study Area. No known deposits of industrial minerals are in any of the study area. All three of the wilderness study areas have a high resource potential for undiscovered deposits of coal and for undiscovered oil and gas.

Dickerson, R.P.; Gaccetta, J.D.; Kulik, D.M.; Kreidler, T.J.

1990-01-01

188

Ares Valles: Night and Day  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 15 June 2004 This pair of images shows part of the Ares Valles region.

Day/Night Infrared Pairs

The image pairs presented focus on a single surface feature as seen in both the daytime and nighttime by the infrared THEMIS camera. The nighttime image (right) has been rotated 180 degrees to place north at the top.

Infrared image interpretation

Daytime: Infrared images taken during the daytime exhibit both the morphological and thermophysical properties of the surface of Mars. Morphologic details are visible due to the effect of sun-facing slopes receiving more energy than antisun-facing slopes. This creates a warm (bright) slope and cool (dark) slope appearance that mimics the light and shadows of a visible wavelength image. Thermophysical properties are seen in that dust heats up more quickly than rocks. Thus dusty areas are bright and rocky areas are dark.

Nighttime: Infrared images taken during the nighttime exhibit only the thermophysical properties of the surface of Mars. The effect of sun-facing versus non-sun-facing energy dissipates quickly at night. Thermophysical effects dominate as different surfaces cool at different rates through the nighttime hours. Rocks cool slowly, and are therefore relatively bright at night (remember that rocks are dark during the day). Dust and other fine grained materials cool very quickly and are dark in nighttime infrared images.

Image information: IR instrument. Latitude 3.6, Longitude 339.9 East (20.1 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

189

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

Microsoft Academic Search

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

D. J. Bove; D. R. Shawe; G. K. Lee; W. F. Hanna; R. E. Jeske

1989-01-01

190

Streamlined Islands in Ares Valles  

NASA Technical Reports Server (NTRS)

(Released 10 June 2002) The Science Although liquid water is not stable on the surface of Mars today, there is substantial geologic evidence that large quantities of water once flowed across the surface in the distant past. Streamlined islands, shown here, are one piece of evidence for this ancient water. The tremendous force of moving water, possibly from a catastrophic flood, carved these teardrop-shaped islands within a much larger channel called Ares Valles. The orientation of the islands can be used as an indicator of the direction the water flowed. The islands have a blunt end that is usually associated with an obstacle, commonly an impact crater. The crater is resistant to erosion and creates a geologic barrier around which the water must flow. As the water flows past the obstacle, its erosive power is directed outward, leaving the area in the lee of the obstacle relatively uneroded. However, some scientists have also argued that the area in the lee of the obstacle might be a depositional zone, where material is dropped out of the water as it briefly slows. The ridges observed on the high-standing terrain in the leeward parts of the islands may be benches carved into the rock that mark the height of the water at various times during the flood, or they might be indicative of layering in the leeward rock. As the water makes its way downstream, the interference of the water flow by the obstacle is reduced, and the water that was diverted around the obstacle rejoins itself at the narrow end of the island. Therefore, the direction of the water flow is parallel to the orientation of the island, and the narrow end of the island points downstream. In addition to the streamlined islands, the channel floor exhibits fluting that is also suggestive of flowing water. The flutes (also known as longitudinal grooves) are also parallel to the direction of flow, indicating that the water flow was turbulent and probably quite fast, which is consistent with the hypothesized catastrophic floods that came through Ares Valles. The Story In symbolism only, these guppy-shaped islands and current-like flutes of land beside them may conjure up a mental image of a flowing Martian river. This picture would only be half-right. Scientifically, no fish ever swam this channel, but these landforms do reveal that catastrophic floods of rushing water probably patterned the land in just this way. Geologists who study flood areas believe that a tremendous force of moving water probably carved both the islands and the small, parallel, 'current-like' ridges around them. The blunt end of the islands (the 'heads' of the 'fish') are probably ancient impact craters that posed obstacles to the water as it rushed down the channel in torrents. Because a crater is resistant to erosion, it creates a geologic barrier around which the water must flow. As the water makes its way downstream, the crater's interference with the water flow is reduced, so the water that was diverted around the obstacle rejoins at the narrow end of the island (the 'tail' of the 'fish'). Therefore, from this information, you can tell that the water flowed from the southeast to the northwest. As a rule of thumb for the future, you can say that the narrow end of the island points downstream. The result may be the island behind the crater, but geologists disagree about the exact process by which the island forms. Some scientists argue that the erosive power of the water is directed outward, leaving the area behind, or in the lee of, the obstacle relatively untouched. Other scientists argue that the water slows when it encounters the crater obstacle, and small particles of sand and 'dirt' drop out of the water and are deposited in the lee. There's another small associated uncertainty too. Look closely at the edges of the islands and notice how the land is terraced. These ledges might mark the height of the water at various times during the flood . . . or they might be an indication that layering occurred. It all depends on your hypothesis. Like the stream

2002-01-01

191

"Internal Waves" Advancing along Submarine Canyons.  

PubMed

Patterns of alternating up- and downcanyon currents have been traced along the axes of submarine canyons off California. The patterns arrive later at stations nearer the heads of coastal canyons. Where a canyon heads between two islands, the patterns advance down the axis. The propagation speeds of these patterns were estimated as 25 to 88 centimeters per second. Internal waves are the probable explanation. PMID:17777263

Shepard, F P; Marshall, N F; McLoughlin, P A

1974-01-18

192

78 FR 7810 - 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...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...

2013-02-04

193

76 FR 24516 - 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...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...

2011-05-02

194

77 FR 9265 - 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...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...

2012-02-16

195

77 FR 43117 - 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...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...

2012-07-23

196

78 FR 21415 - 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...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...

2013-04-10

197

77 FR 22801 - Glen Canyon Dam Adaptive Management Work Group  

Federal Register 2010, 2011, 2012, 2013

...Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY: Bureau of Reclamation...The Glen Canyon Dam Adaptive Management Work Group (AMWG) makes recommendations to...advisory committee, the AMWG, a technical work group, a Grand Canyon Monitoring and...

2012-04-17

198

Global View of Mars Topography  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Annotated Version

This global map of Mars is based on topographical information collected by the Mars Orbiter Laser Altimeter instrument on NASA's Mars Global Surveyor orbiter. Illumination is from the upper right. The image width is approximately 18,000 kilometers (11,185 miles). Candor Chasma forms part of the large Martian canyon system named Valles Marineris. The location of Southwest Candor Chasma is indicated in the annotated version.

2007-01-01

199

Role of submarine canyons in shaping the rise between Lydonia and Oceanographer canyons, Georges Bank  

USGS Publications Warehouse

Three large submarine canyons, Oceanographer, Gilbert, and Lydonia, indent the U.S. Atlantic continental shelf and, with four additional canyons, dissect the continental slope in the vicinity of Georges Bank. On the upper rise, these canyons merge at a water depth of approximately 3100 m to form only two valleys. Differences in channel morphology of the canyons on the upper rise imply differences in relative activity, which is inconsistent with observations in the canyon heads. At present, Lydonia Canyon incises the upper rise more deeply than do the other canyons: however, seismic-reflection profiles show buried channels beneath the rise, which suggests that these other six canyons were periodically active during the Neogene. The rise morphology and the thickness of inferred Neogene- and Quaternary-age sediments on the rise are attributed to the presence and activity of the canyons. The erosional and depositional processes and the morphology of these canyons are remarkably similar to those of fluvial systems. Bear Seamount, which has approximately 2000 m of relief on the rise, has acted as a barrier to downslope sediment transport since the Late Cretaceous. Sediment has piled up on the upslope side, whereas much less sediment has accumulated in the "lee shadow" on the downslope side. Seismic-reflection profile data show that Lydonia Canyon has not eroded down to the volcanic rock of Bear Seamount. ?? 1985.

McGregor, B.A.

1985-01-01

200

A morphologic analysis of Granicus Valles, Mars  

E-print Network

by the melting of ground ice and the removal of meltwater by Granicus Valles. Structural features could have provided pathways for this water effluent. However, the channel pattern appears partly to be structurally influenced. Glacial valleys generally have a... ridges, indicating an earlier ice sheet is consistent with crater densities. An earlier ice sheet could have prevented or destroyed the smaller craters. This strongly supports the conclusion that water was available in the form of ice...

Brandstrom, Gary Wayne

2012-06-07

201

(This is a sample cover image for this issue. The actual cover is not yet available at this time.) This article appeared in a journal published by Elsevier. The attached  

E-print Network

of Valles Marineris, the giant equatorial trough system of Mars, have preserved many tectonic Equatorial glaciations on Mars revealed by gravitational collapse of Valles Marineris wallslopes Daniel Mège-seated gravitational spreading Valles Marineris Mars glaciation trimline moraine normal faulting Martian global climate

Mege, Daniel

202

Loblolly Pines in Pine Creek Canyon  

USGS Multimedia Gallery

Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

203

Barrel Cactus in Pine Creek Canyon  

USGS Multimedia Gallery

Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

204

Snow-covered Sandstone at Bryce Canyon  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

205

Panorama of Bryce Canyon National Park  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

206

Big Canyon Creek Ecological Restoration Strategy  

Microsoft Academic Search

He-yey, Nez Perce for steelhead or rainbow trout (Oncorhynchus mykiss), are a culturally and ecologically significant resource within the Big Canyon Creek watershed; they are also part of the federally listed Snake River Basin Steelhead DPS. The majority of the Big Canyon Creek drainage is considered critical habitat for that DPS as well as for the federally listed Snake River

Lynn Rasmussen; Shannon Richardson

2007-01-01

207

Sunset Panorama in Pine Creek Canyon  

USGS Multimedia Gallery

Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

208

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

209

Bryce Canyon and Grand Staircase-Escalante  

USGS Multimedia Gallery

Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

210

Bryce Canyon and Grand Staircase-Escalante  

USGS Multimedia Gallery

Views along the Queen's Garden Trail in Bryce Canyon National Park; Grand Staircase-Escalante National Monument can be seen in the background. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed d...

211

Chryse Outflow Channel  

NASA Technical Reports Server (NTRS)

A color image of the south Chryse basin Valles Marineris outflow channels on Mars; north toward top. The scene shows on the southwest corner the chaotic terrain of the east part of Valles Marineris and two of its related canyons: Eos and Capri Chasmata (south to north). Ganges Chasma lies directly north. The chaos in the southern part of the image gives rise to several outflow channels, Shalbatana, Simud, Tiu, and Ares Valles (left to right), that drained north into the Chryse basin. The mouth of Ares Valles is the site of the Mars Pathfinder lander.

This image is a composite of Viking medium-resolution images in black and white and low-resolution images in color. The image extends from latitude 20 degrees S. to 20 degrees N. and from longitude 15 degrees to 53 degrees; Mercator projection.

The south Chryse outflow channels are cut an average of 1 km into the cratered highland terrain. This terrain is about 9 km above datum near Valles Marineris and steadily decreases in elevation to 1 km below datum in the Chryse basin. Shalbatana is relatively narrow (10 km wide) but can reach 3 km in depth. The channel begins at a 2- to 3-km-deep circular depression within a large impact crater, whose floor is partly covered by a chaotic material, and ends in Simud Valles. Tiu and Simud Valles consist of a complex of connected channel floors and chaotic terrain and extend as far south as and connect to eastern Valles Marineris. Ares Vallis originates from discontinuous patches of chaotic terrain within large craters. In the Chryse basin the Ares channel forks; one branch continues northwest into central Chryse Planitia (Latin for plain) and the other extends north into eastern Chryse Planitia.

1997-01-01

212

Urban street canyons: Coupling dynamics, chemistry and within-canyon chemical processing of emissions  

NASA Astrophysics Data System (ADS)

Street canyons, formed by rows of buildings in urban environments, are associated with high levels of atmospheric pollutants emitted primarily from vehicles, and substantial human exposure. The street canyon forms a semi-enclosed environment, within which emissions may be entrained in a re-circulatory system; chemical processing of emitted compounds alters the composition of the air vented to the overlying boundary layer, compared with the primary emissions. As the prevailing atmospheric chemistry is highly non-linear, and the canyon mixing and predominant chemical reaction timescales are comparable, the combined impacts of dynamics and chemistry must be considered to quantify these effects. Here we report a model study of the coupled impacts of dynamical and chemical processing upon the atmospheric composition in a street canyon environment, to assess the impacts upon air pollutant levels within the canyon, and to quantify the extent to which within-canyon chemical processing alters the composition of canyon outflow, in comparison to the primary emissions within the canyon. A new model for the simulation of street canyon atmospheric chemical processing has been developed, by integrating an existing Large-Eddy Simulation (LES) dynamical model of canyon atmospheric motion with a detailed chemical reaction mechanism, a Reduced Chemical Scheme (RCS) comprising 51 chemical species and 136 reactions, based upon a subset of the Master Chemical Mechanism (MCM). The combined LES-RCS model is used to investigate the combined effects of mixing and chemical processing upon air quality within an idealised street canyon. The effect of the combination of dynamical (segregation) and chemical effects is determined by comparing the outputs of the full LES-RCS canyon model with those obtained when representing the canyon as a zero-dimensional box model (i.e. assuming mixing is complete and instantaneous). The LES-RCS approach predicts lower (canyon-averaged) levels of NOx, OH and HO2, but higher levels of O3, compared with the box model run under identical chemical and emissions conditions. When considering the level of chemical detail implemented, segregation effects were found to reduce the error introduced by simplifying the reaction mechanism. Chemical processing of emissions within the canyon leads to a significant increase in the Ox flux from the canyon into the overlying boundary layer, relative to primary emissions, for the idealised case considered here. These results demonstrate that within-canyon atmospheric chemical processing can substantially alter the concentrations of pollutants injected into the urban canopy layer, compared with the raw emission rates within the street canyon. The extent to which these effects occur is likely to be dependent upon the nature of the domain (canyon aspect ratio), prevailing meteorology and emission/pollution scenario considered.

Bright, Vivien Bianca; Bloss, William James; Cai, Xiaoming

2013-04-01

213

Third hole planned at Valles Caldera  

NASA Astrophysics Data System (ADS)

Valles caldera, N. Mex., is the culmination of more than 13 million years of volcanism in the Jemez volcanic field and is an excellent model for resurgent calderas and for the high-temperature geothermal systems found with them. This month one of the biggest diamond drills in the world will start the third research core hole in the caldera. Valles Caldera 2B will be the tenth core hole in the Department of Energy's Continental Scientific Drilling Program.CSDP drilling in the 1.1-million-year-old caldera began in 1984 in the southwest moat zone when the research hole Valles Caldera 1 was continuously cored to 856 m. VC-1 intersected a hydrothermal outflow plume from the deep geothermal system. Data indicate multiple episodes of hydrothermal activity in the volcanic field's history, as well as multiple episodes of rhyolite magma generation during evolution of the caldera. The June 10, 1988 (vol. 63), issue of Journal of Geophysical Research—Solid Earth and Planets carried a special section on results from VC-1.

Gardner, Jamie

214

Primary Initiation of Submarine Canyons  

E-print Network

The discovery of close-to-star gas-giant exo-planets lends support to the idea of Earth's origin as a Jupiter-like gas-giant and to the consequences of its compression, including whole-Earth decompression dynamics that gives rise, without requiring mantle convection, to the myriad measurements and observations whose descriptions are attributed to plate tectonics. I propose here another, unanticipated consequence of whole-Earth decompression dynamics: namely, a specific, dominant, non-erosion, underlying initiation-mechanism precursor for submarine canyons that follows as a direct consequence of Earth's early origin as a Jupiter-like gas-giant.

Herndon, J Marvin

2011-01-01

215

Primary Initiation of Submarine Canyons  

E-print Network

The discovery of close-to-star gas-giant exo-planets lends support to the idea of Earth's origin as a Jupiter-like gas-giant and to the consequences of its compression, including whole-Earth decompression dynamics that gives rise, without requiring mantle convection, to the myriad measurements and observations whose descriptions are attributed to plate tectonics. I propose here another, unanticipated consequence of whole-Earth decompression dynamics: namely, a specific, dominant, non-erosion, underlying initiation-mechanism precursor for submarine canyons that follows as a direct consequence of Earth's early origin as a Jupiter-like gas-giant.

J. Marvin Herndon

2011-02-02

216

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

217

ROV Tiburon Investigation of Hawaiian Submarine Canyons  

NASA Astrophysics Data System (ADS)

MBARI conducted ROV dives around the Hawaiian Islands during an expedition of the R/V Western Flyer and Tiburon in the spring of 2001. Eight ROV dives were made to investigate five major submarine canyons offshore of Oahu, Molokai, and Hawaii in up to 3,434 m water depths. Four of these canyons are located off the windward (northern) side of these islands where onshore canyons are also well developed. Those canyons located offshore of Molokai and Oahu incise the head scars of the giant Nuuanu and Wailai submarine landslides. ROV observations and sediment and rock outcrop sampling were made in these canyons to determine their origin and present-day activity. The fifth canyon investigated is located on the leeward (southern) side of Molokai. The canyons along the windward side expose extensive stratigraphic sections that reveal the history of the islands' formation. In composite, these sections contain marine pillow basalt overlain by a substantial sequence of alternating subaerial lava flows, rounded boulder conglomerates, shallow water carbonates, and hyaloclastites that indicate coastal and marine deposition. These sequences illustrate the accretion and subsequent subsidence of the islands' flanks. These canyons also have morphologically distinct upper and lower sections. The upper reaches of the canyons are incised into the shallow water marine facies and contain broad axial channels through which active sediment transport is occurring. In contrast, the morphology of the lower canyons are strongly influenced by the giant landslides that massively altered the northern flanks of the Hawaiian chain. The lower canyons contain plunge pools and steep headwall scarps that are generally comprised of mechanically competent subaerial lava flows. The presence of multiple plunge pools with differentially eroded head scarps suggests retrogressive erosion (bottom-up process) with headward advancement of the various heads. Undercutting of the headwalls also produce periodic rockfalls and debris flows that in combination with the sediment supplied from the upper parts of the canyons is both lengthening and deepening the canyons. This progressive advancement of the erosion along the weaker haloclastite beds has produced a stair-step configuration. In contrast, the canyon we investigated on the leeward side of Molokai showed no evidence of active sediment transport and appears to be filling.

Paull, C. K.; Greene, H. G.; Caress, D. W.; Clague, D. A.; Ussler, W.; Maher, N. M.

2001-12-01

218

Geology and biology of Oceanographer submarine canyon.  

USGS Publications Warehouse

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

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

1980-01-01

219

Prehistoric deforestation at Chaco Canyon?  

PubMed

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

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

2014-08-12

220

Prehistoric deforestation at Chaco Canyon?  

PubMed Central

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

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

2014-01-01

221

Flow near submarine canyons driven by constant winds  

Microsoft Academic Search

Circulation over coastal submarine canyons driven by constant upwelling or downwelling wind stress is simulated and analyzed with a primitive equation ocean model. Astoria Canyon, on the west coast of North America, is the focus of this study, and model results are consistent with most major features of mean canyon circulation observed in Astoria Canyon. Near-surface flow crosses over the

Jun She; John M. Klinck

2000-01-01

222

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 draft Snake Hells Canyon Subbasin Assessment and Snake Hells Canyon Subbasin Management Plan prepared species in the Snake Hells Canyon subbasin. Section II summarizes the prioritization of these limiting

223

Juventae Chasma and Maja Valles, Mars: Further Evidence for Multiple Flooding Events  

NASA Astrophysics Data System (ADS)

Introduction: In this study we investigate the age relationship of Juventae Chasma to the adjacent Maja Valles in order to gain a feasible explanation for the formation and evolution of rhythmic light-toned layered deposits (LLD). In this first step, we use impact crater size-frequency distributions for dating the planetary surface in the regions of interest. Juventae Chasma is located at the northern side of the Valles Marineris and stretches for approximately 150 km east-west and 250 km north-south. The basin floor shows a depth of 5 km and more below the surrounding surface. To the north lies the adjacent Maja Valles, a 50 km to 150 km wide channel extending for 1600 km northward and discharging into the Chryse Planitia plains. Various investigations of several authors have been carried out on this subject in the past, but the formation of the LLD in Juventae Chasma is still poorly understood. The formation theories range from a volcanic origin [1], lake deposits, delta deposits [2] to spring deposits [3]. A very different hypothesis for the formation of the sulfates is deposition from airfall. This could happen as dry deposition from the atmosphere or in co-precipitation with icy materials such as snow crystals or dust particles. This phenomenon is observed at the poles of Mars, where rhythmic layerings occur showing high similarities to the sulfate deposits in Juventae Chasma. The light-toned materials in the chasma show a spectral signature indicative of kieserite in the outcrops A, C and D and in the lower part of B, whereas the upper part of B was described as gypsum [4]. Wendt et al. [5] identified different mineral assemblages in the cap rock of mount B, using the CRISM instrument and the Multiple-Endmember Linear Spectral Unmixing Model (MELSUM). HRSC DTM: The Digital Terrain Model (DTM ) mosaic (see Fig. 1) was derived from 11 HRSC orbits at approximately -7° S to 8° N and 295° to 301° E with a ground resolution of 100 m per pixel and an ortho-image mosaic with a ground resolution of 12.5 m per pixel. The main processing tasks for the DTM derivation are first a pre-rectification of image data using the global MOLA- based DTM, then a least-squares area-based matching between nadir and the other channels (stereo and photometry) in a pyramidal approach and finally, DTM raster generation. Improved orientation data are necessary for high-resolution digital terrain models and orthoimage mosaics. For this purpose, new exterior and interior orientation data, based on tie-point matching have been used. The bundle adjustment approach for photogrammetric point determination with a three-line camera is a least squares adjustment based on the well known collinearity equations [6]. The construction of the HRSC-DTM is the basis for further investigation of the masses and volumes, transported from Juventae Chasma through Maja Valles. We use HRSC and OMEGA (Mars Express), as well as HiRise and CRISM (Mars Reconnaissance Orbiter) data for generally mapping the target area. Crater counting is carried out using CTX and HRSC images. Results: The results of the first determinations of the impact crater size-frequency distributions are presented in Fig. 2 and 3 and show an age of 1.22 Ga (+/- 0.16 Ga) for the western part of the Maja Valles channel. The southeastern channel (close to the streamlined island) shows older ages of 3.68 Ga (+0.08/-0.17 Ga) and 2.18 Ga (+/- 0.31 Ga). This clearly indicates, that multiple flooding events took place in the area. The first results for Juventae Chasma age determinations indicate an age of 3.33 Ga. Conclusions: The HRSC-DTM enables us to examine the study area most accurately. We dated the formation of the Juventae Chasma with an age of at least 3.33 Ga. The investigated sites at Maja Valles clearly show evidences for multiple outflow events. Some of these events took place before the formation of the sulfate deposits in Juventae Chasma. Further age determinations and mapping will be carried out in this area to obtain a chronology of events of this highly interesting area in the equatoria

Gross, C.; Wendt, L.; Dumke, A.; Neukum, G.

2009-04-01

224

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

225

XVIII. TEST HOLES IN THE VALLE TOLEDO AND VALLE GRANDE (1948)  

E-print Network

, gravel, with some clay lenses, all volcanic rock, containing much pumice 350 361 Note: The whole section and pumice 130 140 7. Test Hole 7 Location: Valle Grande Depth: 40 ft Depth to water: 5.5 ft (6-29-48); 6

226

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

227

Wintertime meteorology of the Grand Canyon region  

SciTech Connect

The Grand Canyon region of the American Southwest is an interesting region meteorologically, but because of its isolated location, the lack of major population centers in the region, and the high cost of meteorological field experiments, it has historically received little observational attention. In recent years, however, attention has been directed to episodes of visibility degradation in many of the US National parks, and two recent field studies focused on this visibility problem have greatly increased the meteorological data available for the Grand Canyon region. The most recent and comprehensive of these studies is the Navajo Generating Station Winter Visibility Study of 1989--90. This study investigated the sources of visibility degradation in Grand Canyon National Park and the meteorological mechanisms leading to low visibility episodes. In this paper we present analyses of this rich data set to gain a better understanding of the key wintertime meteorological features of the Grand Canyon region.

Whiteman, C.D.

1992-09-01

228

77 FR 48151 - Boulder Canyon Project  

Federal Register 2010, 2011, 2012, 2013

...specifically apply to the project involved, were transferred...The Boulder Canyon Project Implementation Agreement requires...achieve payment of all costs and financial obligations associated with the project. Each fiscal year,...

2012-08-13

229

75 FR 71102 - Jones Canyon Hydro, LLC; Notice of Preliminary Permit Application Accepted for Filing and...  

Federal Register 2010, 2011, 2012, 2013

...13860-000] Jones Canyon Hydro, LLC; Notice of Preliminary...2010, Jones Canyon Hydro, LLC (Jones Canyon Hydro) filed an application...of the Jones Canyon Pumped Storage Project (Project...800-foot-long, underground transmission line...

2010-11-22

230

Wilmington Submarine Canyon: a marine fluvial-like system.  

USGS Publications Warehouse

Midrange sidescan sonar data show that a system of gullies and small channels feeds into large submarine canyons on the Middle Atlantic Continental Slope of the US. The surveyed canyons all have relatively flat floors, but they have different channel morphologies. Wilmington Canyon has a meandering channel that extends down the Continental Slope and across the Continental Rise, whereas two canyons south of Wilmington Canyon have straight channels that trend directly downslope onto the rise. The morphology of these submarine canyon systems is remarkably similar to that of terrestrial fluvial systems.-Authors

McGregor, B.; Stubblefield, W.L.; Ryan, William B. F.; Twichell, D.C.

1982-01-01

231

Modelling the flow over submarine canyons  

NASA Astrophysics Data System (ADS)

The aim of this work is within EUROSTRATAFORM project and consists on developing a model for sedimentary processes and their forcing conditions on the European continental margin (main concern on Nazaré and Setúbal Canyons), constrained by the requirement of considering the continental margin as a continuum and of following the sediments from their source to their settling and accumulation sites. The work will be based on MOHID modelling system (http://www.mohid.com), which includes modules for hydrodynamics, sediment transport and ecology and permits eulerian and lagrangian simulations. The model allows the use of several vertical discretizations and variable horizontal grids, including nested models. Canyons are local geographical accidents where currents are forced both by regional circulation and local forcing mechanisms. Simulation of physical and sedimentary processes requires a fine local discretizaton embedded into a regional model in order to describe accurately their topography. Inside canyons topography and currents interact non-linearly. Their simulation requires adequate vertical grids. A lagrangian grid will be used to minimize numerical diffusion associated to high frequency vertical oscillation generated by internal tides. Sediment transport will be simulated using eulerian and lagrangian formulations. Effects of windstorm waves will be simulated explicitly on re-suspension along submerse beaches. Preliminary results will be presented for the real canyons in a coarse grid. Real topography simulations are forced by density and wind. The results show that canyons by one way or another are likely to induce upwelling in the water column and thus are very productive locals. For the particular case of Nazaré canyon it is shown that flow interacts both with the submarine canyon and with coastal morphology.

Coelho, H. S.; Neves, R.; Leitao, P. C.; Garcia, A. C.

2003-04-01

232

Layers Exposed at Polar Canyon  

NASA Technical Reports Server (NTRS)

This false-color subframe of an image from the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter shows the north polar layered deposits at top and darker materials at bottom, exposed in a scarp at the head of Chasma Boreale, a large canyon eroded into the layered deposits.

The polar layered deposits appear red because of dust mixed within them, but are ice-rich as indicated by previous observations. Water ice in the layered deposits is probably responsible for the pattern of fractures seen near the top of the scarp. The darker material below the layered deposits may have been deposited as sand dunes, as indicated by the crossbedding (truncation of curved lines) seen near the middle of the scarp. It appears that brighter, ice-rich layers were deposited between the dark dunes in places. Exposures such as these are useful in understanding recent climate variations that are likely recorded in the polar layered deposits.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.

2006-01-01

233

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

234

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

USGS Publications Warehouse

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

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

1990-01-01

235

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

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

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

236

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

237

75 FR 34476 - Glen Canyon Dam Adaptive Management Work Group  

Federal Register 2010, 2011, 2012, 2013

...Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY: Bureau of Reclamation, Interior...for the Glen Canyon Dam Adaptive Management Work Group. The purpose of the Adaptive Management Work Group is to advise and to provide...

2010-06-17

238

Contemporary Sediment-Transport Processes in Submarine Canyons  

NASA Astrophysics Data System (ADS)

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.

Puig, Pere; Palanques, Albert; Martín, Jacobo

2014-01-01

239

Geomorphic clues to the Martian volatile inventory: Landslides  

NASA Technical Reports Server (NTRS)

Eight landslide locales were selected in Valles Marineris for preliminary geomorphological mapping. Four main suites of morphological features were identified. In four order outward from the head scarp they are: (1) large ridges in head area, transverse to movement direction, probably slump blocks or pieces of wall that fell or toppled, possibly backward rotated; (2) smaller ridges, convex toward distal edge of slides, many with lobate pattern, some possibly step like scarps rather than ridges; (3) thin, sheet like debris cover, forms discrete fan shaped lobe with edge scarps unconfined; and (4) low transverse, continuous ridges (possibly folds) found at distal edge of slides, where debris appears to have encountered obstructions (e.g., opposing canyon walls), but not all confined slides exhibit this feature. Any one landslide can possess all or some of these features. Slides in the western Valles Marineris are more complex and show more variety than those in the eastern part.

Pieri, D.; Kirkpatrick, A.

1984-01-01

240

Upwelling flow dynamics in long canyons at low Rossby number  

NASA Astrophysics Data System (ADS)

Submarine canyons, topographic features incising the continental slope, vary in both shape and size. The dynamics of short canyons have been observed and described in the field, in the laboratory, and with numerical simulations. Flow within long canyons, such as Juan de Fuca canyon, located between Vancouver Island and Washington State in the Pacific Northwest, is less well understood. Physical models of both long and short canyons have been constructed to understand the upwelling dynamics in long canyons and how upwelling changes, as compared with the dynamics of short canyons, at low Rossby number. Stratification and rotation, both important parameters in determining the dynamics in canyons, can be controlled and scaled accordingly for replication of oceanic conditions. The physical model is spun up to an initial rotation rate, and the flow is forced by increasing the rotation rate over the equivalent of several days. Flow visualization is used to determine the strength and location of upwelling, the strength and mechanisms generating vorticity, as well as the differences between the flow within the long and short canyons. The pattern of upwelling between the two canyons is significantly different in the horizontal with upwelling occurring through the canyon head in the short canyon and upwelling occurring close to the mouth along the downstream rim in the long canyon. At high Rossby number, upwelling is similar in both the long and short canyon and is driven by advection. However, as Rossby number decreases, the flow in the long canyon is more strongly affected by the strong convergence of the isobaths near the canyon than by advection alone.

Waterhouse, Amy F.; Allen, Susan E.; Bowie, Alexander W.

2009-05-01

241

Financial Analysis of Experimental Releases Conducted at Glen Canyon Dam  

E-print Network

Financial Analysis of Experimental Releases Conducted at Glen Canyon Dam during Water Years 2006 Canyon Dam during Water Years 2006 through 2010 ANL/DIS-11-4 by L.A. Poch,1 T.D. Veselka,1 C.S. Palmer,2 Canyon Dam (GCD) conducted for the U.S. Department of Energy's Western Area Power Administration (Western

Kemner, Ken

242

THE ORIGI N ANDSEDIMENTOLOGYOF THE PUNASUBMARINE CANYON,HAhIAII  

E-print Network

artd geochemistry. The deep canyon is domitrated by pelaqic cl,ay. Ihe southern learshore -and riftTHE ORIGI N ANDSEDIMENTOLOGYOF THE PUNASUBMARINE CANYON,HAhIAII A DISSERTATIONSUBMITTEDTO Submarrne Canyon lres oFf the east coast of Lhe rsland of Hawarr, the youngest rsland of the Hawallan Charn

Luther, Douglas S.

243

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

244

Authigenic clay minerals in sandstones of the Delaware Mountain Group: Bell Canyon and Cherry Canyon Formations, Waha Field, West Texas  

E-print Network

AUTHIGENIC CLAY MINERALS IN SANDSTONES OF THE DELAWARE MOUNTAIN GROUP: BELL CANYON AND CHERRY CANYON FORMATIONS, WAHA FIELD, WEST TEXAS A Thesis by SUZETTE DENISE WALLING Submitted to the Office of Graduate Studies of Texas A&M University... Minerals in Sandstones of the Delaware Mountain Group: Bell Canyon and Cherry Canyon Formations, Waha Field, West Texas. (December 1992) Suzette Denise Walling, B. S. , Texas A8tM University Chair of Advisory Committee: Dr. Thomas T. Tieh Late...

Walling, Suzette Denise

2012-06-07

245

Geology Fieldnotes: Bryce Canyon National Park, Utah  

NSDL National Science Digital Library

Located on the Colorado Plateau in Utah, this canyon is comprised mostly of sedimentary rocks, and continues to be eroded and shaped by the Paria River. Its geologic and human history are outlined on this site, including the formation of the canyon, from the Cretaceous period (144 million years ago) to the present, and geologic features, such as fins, columns, pinnacles, and hoodoos. Visitor information, links to other resources, maps, and a teacher feature (resources for teaching geology with National Park examples) are also available.

Foos, Annabelle

246

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 dis

247

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

ERIC Educational Resources Information Center

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

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

248

Heterogeneity and lithotype distribution in ancient deep-sea canyons: Point Lobos deep-sea canyon as a reservoir analogue  

Microsoft Academic Search

An evolution and history of filling is proposed for an exceptionally exposed ancient deep-sea canyon on a Paleocene oblique-slip tectonic margin which, on a number of scales, reveals, successive phases of canyon activity. The quantitative methods adopted for this study make it of direct use to modellers as an example of reservoir heterogeneity in an ancient canyon fill, where facies

Bryan T. Cronin; Robert B. Kidd

1998-01-01

249

Numerical simulations of the internal tide in a submarine canyon  

NASA Astrophysics Data System (ADS)

Three-dimensional numerical simulations of the generation and propagation of the semidiurnal internal tide in a submarine canyon with dimensions similar to those of the Monterey Canyon are carried out using a primitive equation model. Forcing with just sea level at the offshore boundary in an initially horizontally homogeneous ocean with realistic vertical stratification, internal tides are generated at the canyon foot and rim, and along portions of the canyon floor. The results compare favorably with observations, both indicating enhancement of energy along the canyon floor propagating at an angle consistent with linear internal wave theory. Due to the earth's rotation, internal tide energy is distributed asymmetrically in the cross-canyon direction, favoring the southern side. The effect of canyon floor slope is explored, with the finding that small changes in the slope result in large changes in the amount and distribution of the internal tide energy. Canyons whose floors are subcritical with respect to the semidiurnal frequency along their entire length have very little baroclinic energy, whereas canyons that are near-critical along much of their length, such as the Monterey Canyon, develop strong internal tides that propagate shoreward. Canyons that are near-critical at their mouths but supercritical further inshore generate the most internal tidal energy overall, although little of it makes it onto the continental shelf shoreward of the canyon head. The effects of internal tides within the canyons can be seen outside the canyons as well. Water is transported from depth onto the adjacent continental shelf along the canyon rims. This tidal pumping can be responsible for alongshore internal tide propagation and tidal-period surface currents with relatively small horizontal scales of variability.

Petruncio, Emil T.; Paduan, Jeffrey D.; Rosenfeld, Leslie K.

2002-06-01

250

Interacting ocean waves explain powerful seafloor canyon flows  

NASA Astrophysics Data System (ADS)

Off the southwestern coast of Taiwan the Gaoping Submarine Canyon meanders in a giant backward S shape as it stretches southwestward toward the South China Sea. In the canyon, a 200-meter-deep cut into the seafloor that lies 300 meters below the sea's surface, the waters carry an usually large amount of internal tidal power—9.1 megawatts from the canyon's mouth to its head. Along with the strong flows a region of enhanced vertical mixing sits at the canyon's head. Researchers had previously attributed the anomalous flows to internal waves pushing through the Gaoping Canyon, though the source of the energy remained an open question.

Schultz, Colin

2012-02-01

251

Rejuvenation of submarine canyon associated with ridge subduction, Tenryu Canyon, off Tokai, central Japan  

Microsoft Academic Search

The 130-km-long Tenryu Canyon is an active deep water meandering canyon transversely developed on the tectonically active Tokai (Eastern Nankai) accretionary prism, where the multiple intraplate deformation caused by the arc–arc Izu collision. Over 2000 km of EM 12 data, 3.5-kHz profiles and PASISAR profiles obtained during the KAIKO-TOKAI Project, 1996, IZANAGI data, the bathymetric chart, and the preexisting seismic

Wonn Soh; Hidekazu Tokuyama

2002-01-01

252

Grand Canyon, Lake Powell, and Lake Mead  

NASA Technical Reports Server (NTRS)

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

2002-01-01

253

Bryce Canyon and Grand Staircase-Escalante  

USGS Multimedia Gallery

In the foreground are sandstone hoodoos and in the background is the Grand Staircase-Escalante National Monument, which is managed by the Bureau of Land Management. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars...

254

Map Your Way to the Grand Canyon  

ERIC Educational Resources Information Center

In the introductory assignment, each randomly assigned group spends about 10 to 15 minutes at each station. The author incorporates as much sensory stimulation in the activity as possible. At the first station, students view a PowerPoint show from a geology class the author participated in at the Grand Canyon. At station two, students look at a…

Yoder, Holly

2005-01-01

255

Modelling Aerosol Dispersion in Urban Street Canyons  

Microsoft Academic Search

Flow patterns within an urban street canyon are influenced by various micrometeorological factors. It also represents an environment where pollutants such as aerosols accumulate to high levels due to high volumes of traffic. As adverse health effects are being attributed to exposure to aerosols, an investigation of the dispersion of aerosols within such environments is of growing importance. In particular,

B. K. Tay; D. P. Jones; M. W. Gallagher; G. B. McFiggans; A. P. Watkins

2009-01-01

256

Canyon incision model for prograding continental slopes  

Microsoft Academic Search

Continental slopes have a number of features in common with subaerial landscapes, which suggest that some concepts and methodologies for representing landscape form and process developed in subaerial quantitative geomorphology could be adapted for studying them. As part of that general effort, we have developed a model for deep canyons on the USA East coast continental slope, which are believed

N. C. Mitchell; W. B. Dade

2003-01-01

257

Internal modes in a submarine canyon  

SciTech Connect

A simple analytical model is presented for internal waves in a slot of variable width. This model is used to explain the vertical wave length, directional character, and amplitude enhancement of internal waves observed near the axis of La Jolla Submarine Canyon, offshore of San Diego, California.

Gordon, R.L.

1982-01-20

258

North Atlantic slope and canyon study. Volume 1. Executive summary  

SciTech Connect

A field program to investigate the currents and sediment transport along the outershelf and upper slope along the southern flank of Georges Bank was conducted between 1980 and 1984. A major part of the field experiment was conducted in Lydonia Canyon, a large submarine canyon which cuts northward about 20 km into the continental shelf from the shelfbreak. A smaller experiment was conducted in Oceanographer Canyon to compare the currents in these two major canyons. The long-term current observations made in Lydonia and Oceanographer Canyons show that the current regime in these topographic features differs from the adjacent slope, and between canyons. Sediments near the head (depths shallower than about 600 m) in both Lydonia and Oceanographer are frequently resuspended. This frequent resuspension may allow the sediments to strip pollutants from the water column. Currents in Oceanographer Canyon are stronger and the sediments coarser than in Lydonia at comparable depths.

Butman, B.

1986-12-01

259

Anatomy of La Jolla submarine canyon system; offshore southern California  

USGS Publications Warehouse

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

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

2013-01-01

260

Athabasca Valles, Mars: A lava-draped channel system  

USGS Publications Warehouse

Athabasca Valles is a young outflow channel system on Mars that may have been carved by catastrophic water floods. However, images acquired by the High-Resolution Imaging Science Experiment camera onboard the Mars Reconnaissance Orbiter spacecraft reveal that Athabasca Valles is now entirely draped by a thin layer of solidified lava - the remnant of a once-swollen river of molten rock. The lava erupted from a fissure, inundated the channels, and drained downstream in geologically recent times. Purported ice features in Athabasca Valles and its distal basin, Cerberus Palus, are actually composed of this lava. Similar volcanic processes may have operated in other ostensibly fluvial channels, which could explain in part why the landers sent to investigate sites of ancient flooding on Mars have predominantly found lava at the surface instead.

Jaeger, W.L.; Keszthelyi, L.P.; McEwen, A.S.; Dundas, C.M.; Russell, P.S.

2007-01-01

261

Big Canyon Creek Ecological Restoration Strategy.  

SciTech Connect

He-yey, Nez Perce for steelhead or rainbow trout (Oncorhynchus mykiss), are a culturally and ecologically significant resource within the Big Canyon Creek watershed; they are also part of the federally listed Snake River Basin Steelhead DPS. The majority of the Big Canyon Creek drainage is considered critical habitat for that DPS as well as for the federally listed Snake River fall chinook (Oncorhynchus tshawytscha) ESU. The Nez Perce Soil and Water Conservation District (District) and the Nez Perce Tribe Department of Fisheries Resources Management-Watershed (Tribe), in an effort to support the continued existence of these and other aquatic species, have developed this document to direct funding toward priority restoration projects in priority areas for the Big Canyon Creek watershed. In order to achieve this, the District and the Tribe: (1) Developed a working group and technical team composed of managers from a variety of stakeholders within the basin; (2) Established geographically distinct sub-watershed areas called Assessment Units (AUs); (3) Created a prioritization framework for the AUs and prioritized them; and (4) Developed treatment strategies to utilize within the prioritized AUs. Assessment Units were delineated by significant shifts in sampled juvenile O. mykiss (steelhead/rainbow trout) densities, which were found to fall at fish passage barriers. The prioritization framework considered four aspects critical to determining the relative importance of performing restoration in a certain area: density of critical fish species, physical condition of the AU, water quantity, and water quality. It was established, through vigorous data analysis within these four areas, that the geographic priority areas for restoration within the Big Canyon Creek watershed are Big Canyon Creek from stream km 45.5 to the headwaters, Little Canyon from km 15 to 30, the mainstem corridors of Big Canyon (mouth to 7km) and Little Canyon (mouth to 7km). The District and the Tribe then used data collected from the District's stream assessment and inventory, utilizing the Stream Visual Assessment Protocol (SVAP), to determine treatment necessary to bring 90% of reaches ranked Poor or Fair through the SVAP up to good or excellent. In 10 year's time, all reaches that were previously evaluated with SVAP will be reevaluated to determine progress and to adapt methods for continued success. Over 400 miles of stream need treatment in order to meet identified restoration goals. Treatments include practices which result in riparian habitat improvements, nutrient reductions, channel condition improvements, fish habitat improvements, invasive species control, water withdrawal reductions, improved hydrologic alterations, upland sediment reductions, and passage barrier removal. The Nez Perce Soil and Water Conservation District (District) and the Nez Perce Tribe Department of Fisheries Resource Management Watershed Division (Tribe) developed this document to guide restoration activities within the Big Canyon Creek watershed for the period of 2008-2018. This plan was created to demonstrate the ongoing need and potential for anadromous fish habitat restoration within the watershed and to ensure continued implementation of restoration actions and activities. It was developed not only to guide the District and the Tribe, but also to encourage cooperation among all stakeholders, including landowners, government agencies, private organizations, tribal governments, and elected officials. Through sharing information, skills, and resources in an active, cooperative relationships, all concerned parties will have the opportunity to join together to strengthen and maintain a sustainable natural resource base for present and future generations within the watershed. The primary goal of the strategy is to address aquatic habitat restoration needs on a watershed level for resident and anadromous fish species, promoting quality habitat within a self-sustaining watershed. Seven objectives have been developed to support this goal: (1) Identify factors limiting quality

Rasmussen, Lynn; Richardson, Shannon

2007-10-01

262

Local Sulfate-rich Layered Deposits in Noctis Labyrinthus, Mars, and Their Chronological Consequences  

NASA Astrophysics Data System (ADS)

The theiikian period has been postulated to end the primitive "wet" period of Mars history at a time when the liquid water was already scarce at the surface of Mars. The basis for such a chronology is the presence of sulfates formed after the Noachian period, such as those deposited inside Valles Marineris canyons, which opened in the Early Hesperian epoch. Nevertheless, the end of this period is poorly constrained because the ages of layered deposits, and the associated alteration, are difficult to know precisely. Secondly, sulfates form by aqueous alteration of basaltic materials, and the resulting fluids can move far from their point of genesis. The main interior deposits of Valles Marineris miss the context of deposition that could have allowed us a better understanding of the sulfates' origin. In this context, regions such as the canyons of Noctis Labyrinthus studied here are key regions to solve these two questions. Indeed, these crosscutting canyons of deep and narrow shape display fresh scarps without spur and gully erosion and cut plains of Late Hesperian age, indicating a younger age than the main canyons of Valles Marineris. Several flat areas inside Noctis canyons display strong signatures of pyroxenes according to OMEGA spectroscopic data over high thermal inertia outcrops. This suggests the existence of young lava flows (see Mangold et al., LPSC, 2008). Additionally, several layered deposits exist locally which do not display features at the OMEGA scale. At this location, CRISM data allow us a close-up into the layered deposits at a spatial sampling of about 20 meters. Over these light toned layers, we detect sulfates and a collection of hydration signatures that might be related to other hydrated minerals. This material does not represent a major volume of alteration material compared to the main canyons accumulation, but it corresponds to some of the latest signatures of alteration found yet, perhaps of similar age as the alteration found on Valles Marineris plateau (see Milliken et al., LPSC, 2008). ). Our study will ultimately try to discriminate the origin of this local alteration: (1) is it related to the heat transfer and fluid circulation created by the volcanic event observed in the surroundings? In that case, this would deny any global consequence. Or, (2) is it one of the last "oasis" of the theiikian period characterized by episodic standing bodies of water?

Mangold, N.; Milliken, R.; Roach, L.; Poulet, F.; Le Mouelic, S.; Loizeau, D.; Ansan, V.; Bibring, J.; Langevin, Y.; Gondet, B.; Murchie, S.; Mustard, J. F.

2008-12-01

263

Lava Flows in the Grand Canyon  

NASA Technical Reports Server (NTRS)

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

2003-01-01

264

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

265

3D View of Grand Canyon, Arizona  

NASA Technical Reports Server (NTRS)

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

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

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

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

2000-01-01

266

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

267

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

268

Grand Canyon Monitoring and Research Center  

NSDL National Science Digital Library

Created in 1995, the Grand Canyon Monitoring and Research Center (GCMRC) was created in order to measure the effects of Glen Canyon Dam operations on natural and physical resources along the Colorado River. As such, the GCMRC's projects also monitor and examine the biological, cultural, and physical resources of the entire Colorado River ecosystem. The materials on their site are divided into five primary sections, including "News & Info", "Research", and "Products". In the "News & Info" area visitors can learn about the endangered species that reside in the area covered by the GCMRC and also take a look at their outreach materials, which include fact sheets, posters, and transcripts from recent symposia. The "Research" area is a bit more technical in nature, containing papers on water flow simulations and elevation data. The site is rounded out by the "Products" area, where visitors can look over new publications and evaluate simulation models.

269

Green Canyon wells require well-engineered drilling programs  

Microsoft Academic Search

Drilling in the Green Canyon area poses technical and operational challenges for operators and the oil field service industry. Amerada Hess Inc.'s success in carrying out a two-well exploratory program in Green Canyon's Block 66 was due to a well-coordinated team effort, carefully designed drilling plan, and prudent operating procedures. The Green Canyon area is located 75 miles offshore, southwest

J. Corley; C. Vice; T. McCary; B. Decker

1986-01-01

270

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

271

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

Federal Register 2010, 2011, 2012, 2013

...INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group (AMWG...SUMMARY: The Glen Canyon Dam Adaptive Management Program (AMP) was...Decision on the Operation of Glen Canyon Dam Final Environmental Impact Statement...

2010-07-29

272

75 FR 20381 - Glen Canyon Dam Adaptive Management Work Group (AMWG)  

Federal Register 2010, 2011, 2012, 2013

...INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group (AMWG...SUMMARY: The Glen Canyon Dam Adaptive Management Program (AMP) was...Decision on the Operation of Glen Canyon Dam Final Environmental Impact Statement...

2010-04-19

273

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

Federal Register 2010, 2011, 2012, 2013

...4073000] Glen Canyon Dam Adaptive Management Work Group Meetings AGENCY: Bureau of Reclamation...The Glen Canyon Dam Adaptive Management Work Group (AMWG) makes recommendations to...advisory committee, the AMWG, a technical work group (TWG), a Grand Canyon...

2013-07-17

274

Uranium-series age determination of calcite veins, VC-1 drill core, Valles Caldera, New Mexico  

NASA Astrophysics Data System (ADS)

Uranium-series analysis (238U-234U-230Th) of 13 calcite veins from the hydrothermally altered Madera Limestone in the VC-1 drill core was performed to determine the ages of the veins and their relation to the Valles hydrothermal system. Thermal water from VC-1 and two hot springs in San Diego Canyon was analyzed for U and (234U/238U) to help evaluate the constancy of initial (234U/238U). The (230Th/234U) age of one of the veins is ˜95 kyr, and those of two other veins are ˜230 and ˜250 kyr. Five of the veins have near equilibrium (230Th/234U) and are probably older than ˜0.3 m.y. Uranium concentrations in the remaining veins are too low for analysis by the ?-spectrometry techniques employed in this study. Of the five veins near (230Th/234U) equilibrium, four are also near (234U/238U) equilibrium, suggesting ages greater than ˜1.0 m.y., but one has (234U/238U) = 1.15, suggesting an age between ˜0.3 and ˜1.0 m.y. Calculated initial (234U/238U) of the veins yielding relatively young ages are neither equal to each other nor to (234U/238U) in thermal water from VC-1, indicating inconstancy of initial (234U/238U) that may be related to variations in groundwater mixing proportions. Three of the four veins that yield relatively young ages consist of coarse, sparry, vuggy calcite, suggesting that this may be the type of calcite vein which forms under conditions resembling those encountered presently in VC-1. The analytical data are consistent with closed-system behavior of U and Th in the VC-1 calcite veins.

Sturchio, Neil C.; Binz, Carl M.

1988-06-01

275

Calorimetric study of melted DNA glass Jessica Valle-Orero  

E-print Network

us to derive quantitative information on the relaxations of the DNA films, in particular to evaluateCalorimetric study of melted DNA glass Jessica Valle-Orero , Jean-Luc Garden , Jacques Richard differential scanning calorimetry (DSC) of the glassy behaviour of films made from DNA fibers. We show

Boyer, Edmond

276

Ascension Submarine Canyon, California - Evolution of a multi-head canyon system along a strike-slip continental margin  

USGS Publications Warehouse

Ascension Submarine Canyon, which lies along the strike-slip (transform) dominated continental margin of central California, consists of two discrete northwestern heads and six less well defined southeastern heads. These eight heads coalesce to form a single submarine canyon near the 2700 m isobath. Detailed seismic stratigraphic data correlated with 19 rock dredge hauls from the walls of the canyon system, suggest that at least one of the two northwestern heads was initially eroded during a Pliocene lowstand of sea level ???3.8 m.y. B.P. Paleogeographic reconstructions indicate that at this time, northwestern Ascension Canyon formed the distal channel of nearby Monterey Canyon and has subsequently been offset by right-lateral, strike-slip faulting along the San Gregorio fault zone. Some of the six southwestern heads of Ascension Canyon may also have been initially eroded as the distal portions of Monterey Canyon during late Pliocene-early Pleistocene sea-level lowstands (???2.8 and 1.75 m.y. B.P.) and subsequently truncated and offset to the northwest. There have also been a minimum of two canyon-cutting episodes within the past 750,000 years, after the entire Ascension Canyon system migrated to the northwest past Monterey Canyon. We attribute these late Pleistocene erosional events to relative lowstands of sea level 750,000 and 18,000 yrs B.P. The late Pleistocene and Holocene evolution of the six southeastern heads also appears to have been controlled by structural uplift of the Ascension-Monterey basement high at the southeastern terminus of the Outer Santa Cruz Basin. We believe that uplift of this basement high sufficiently oversteepened submarine slopes to induce gravitational instability and generate mass movements that resulted in the erosion of the canyon heads. Most significantly, though, our results and interpretations support previous proposals that submarine canyons along strike-slip continental margins can originate by tectonic trunction and lateral offset. ?? 1986.

Nagel, D.K.; Mullins, H.T.; Greene, H. Gary

1986-01-01

277

Crustal Fractures of Ophir Planum  

NASA Technical Reports Server (NTRS)

(Released 29 April 2002) The Science This THEMIS image covers a tract of plateau territory called Ophir Planum. The most obvious features in this scene are the fractures (ranging from 1 to 5 km wide) running from the upper left to lower right. Localized rifting and deep-seated tension fracturing of the crust probably formed these cracks. The wall rock displayed in the upper part of the cliffs appears to be layered. The southwest-facing wall of the largest and uppermost fracture has classic spur and gully topography. This type of topography is created by differing amounts of erosion. Also seen in this image are some scattered impact craters and some dark wind streaks in the lower right. The Ophir Planum plateau separates two separate smaller canyon systems, not visible in this image, (Candor Chasma to the north and Melas Chasma to the south) in the Valles Marineris canyon complex. The whole Valles Marineris canyon system extends some 4,000 km across the equatorial realms of Mars. For comparison, this would stretch from New York City to San Francisco. The Story Plateaus and spurs might make you think of cowboys on the open plain. 'Spurs' in this context, however, are simply ridges that can be seen on the side of the southwest-facing wall of the large fracture that splits the terrain. Gullies stretch down this slope as well. Both of these features are caused by erosion, which is a mild force of change compared to whatever tension cracked the crust and ripped apart the land. The wall rock displayed in the upper part of the cliffs appears to be layered, suggesting that different kinds of rocks and minerals can be found in each banded zone. The Ophir Planum plateau separates two separate canyon systems in the Valles Marineris complex, the largest canyon in the solar system. If Valles Marineris were on Earth, it would stretch from New York City all the way to San Francisco. That will give you some idea of the geological forces that have acted upon the planet over time. Look for scattered impact craters and some dark wind streaks in the deep dark terrain (lower right) as well.

2002-01-01

278

PRUNUS PADUS L. IN VALLE DELL'AVIO (ALTA VALLE CAMONICA, BRESCIA) Entità della popolazione, aspetti geobotanici e fitogeografici della nuova stazione  

Microsoft Academic Search

Prunus padus L. in Valle dell'Avio. characters of population, geobotany and phytogeography of new occurren- ce - We report a new occurrence of Prunus padus in Valle del- l'Avio, Adamello Group, Provincia of Brescia (Italian Alps). The population structure have been described. The autoeco- logy and sinecology of this population are investigated in rela- tion to geomorphology. The discovered population

STEFANO ARMIRAGLIO; RODOLFO GENTILI; CARLO BARONI

2005-01-01

279

Sediment deposition in a modern submarine canyon: Eel Canyon, northern California  

Microsoft Academic Search

Previous studies on the Eel margin have shown that a substantial amount of terrigenous sediment may be rapidly transported and deposited seaward of the shelf break during the Eel River flooding season. Eel Canyon, located ?10 km seaward of the Eel River mouth, has been investigated to determine its role in seaward escape of sediment over seasonal timescales. In order

B. L. Mullenbach; C. A. Nittrouer; P. Puig; D. L. Orange

2004-01-01

280

A natural analogue for high-level waste in tuff: Chemical analysis and modeling of the Valles site  

SciTech Connect

The contact between an obsidian flow and a steep-walled tuff canyon was examined as an analogue for a high-level 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 40}Ar 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 m 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.W.; Krumhansl, J.L.; Ho, C.K. [Sandia National Labs., Albuquerque, NM (United States); Kovach, L. [US Nuclear Regulatory Commission, Washington, DC (United States); McConnell, V.S. [Univ. of Alaska, Fairbanks, AK (United States)

1995-03-01

281

GEOLOGY OF THE ROCK CANYON CREEK FLUORITEMARE EARTH ELEMENT SHOWING  

E-print Network

The Rock Canyon Creek showing (Candy and Deep Purple claims) is hosted by Middle Devonian carbonate rocks in the southem Rocky Mountains oi British Columbia. The property lies near the headwaters of Rock Canyon Creek (Figure 4-2-11 in thr eastern

Southern Rocky Mountains; Jennifer Pel; Z. D. Hora

282

Wind-tunnel study of concentration fields in street canyons  

Microsoft Academic Search

The paper presents results from a case study of gaseous pollutant dispersion in street canyons. Tracer-gas experiments were performed in a neutrally stratified wind tunnel. Vehicle emissions were simulated as line sources. Concentration profiles along building walls were measured. A two-dimensional street canyon was considered as the reference case. The influence of systematic parameter variations on the concentration field is

P Kastner-Klein; E. J Plate

1999-01-01

283

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

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

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

284

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

285

The kinematics of debris flow transport down a canyon  

E-print Network

of gneiss, schist, migmatite and pegmatite (Bryant, 1979)(The term "canyon" is used to refer to the entire erosional valley between the two bounding ridges. The term "channel" will refer to the more confined, deepest, and most central part of the canyon...

Santi, Paul M.

2012-06-07

286

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.

287

Academy of the Canyons Report, Fall 2000-Spring 2002.  

ERIC Educational Resources Information Center

Summarizes findings from an evaluation of the Academy of the Canyons, a "middle college high school" which operates on the College of the Canyons (California) campus and is open to 11th and 12th grade students whose needs are not being met by the large comprehensive high schools. This evaluation, prepared as a component of the Academy's…

Meuschke, Daylene M.; Dixon, P. Scott; Gribbons, Barry C.

288

Calcareous nannoplankton and benthic foraminiferal assemblages from the Nazar Canyon  

E-print Network

Calcareous nannoplankton and benthic foraminiferal assemblages from the Nazaré Canyon (Portuguese, Portugal E-mail: catarina.guerreiro@hidrografico.pt Abstract. Submarine canyons are assumed to play as preferential conduits between the littoral and deep oceanic domain. Here we present first results

289

Abyssal Canyons and Mixing by Low-Frequency Flow  

Microsoft Academic Search

The role canyons play in abyssal mixing is discussed, with a focus on the issue of low-frequency flow over sills and associated overturning instability as opposed to tidally generated mixing. Flow through several deep canyons on the mid-ocean ridge is reviewed and some global consequences are discussed.

K. G. Speer; A. M. Thurnherr

290

Canyon dynamics and related sedimentary impacts off western Portugal  

Microsoft Academic Search

Submarine canyons are areas of increased exchanges between the continental shelf and the deep ocean. We present preliminary results from a multidisciplinary research focussing the dynamics of several canyon systems that occur along the Portuguese continental margin. The research is being conducted in the framework of EU project Eurostrataform and aims to understand the dominant aspects of the interaction between

J. Vitorino; A. Oliveira; R. Silva; L. Quaresma; R. Marreiros

2003-01-01

291

The Barrow submarine Canyon: A drain for the chukehi sea  

Microsoft Academic Search

Oceanographic measurements made in the spring through holes in the ice in an area off Barrow, where the Barrow Canyon forms a sloping trough from the shallow Chukehi Sea into the deep Beaufort Sea, have revealed two interacting water movements: (1) a flow of highly saline water from the shallow Chukehi Sea into the Beaufort Sea through the Barrow Canyon

G. R. Garrison; P. Becker

1976-01-01

292

Geology Fieldnotes: Canyon De Chelly National Monument, Arizona  

NSDL National Science Digital Library

This canyon cuts through the sandstones of the De Chelly formation, of Permian age (200 million years old). The river forming the canyon is the Rio De Chelly, which begins in the nearby Chuska Mountains. Details on this site include some geology, visitor information, photographs, and area maps. Also discussed are details on seeing the park, and Native American history of the area.

293

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.

Thibedeau, Joe

294

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 6/1/13 to 6/30/13

Vanderhoff, Alex

295

Green Machine Florida Canyon Hourly Data 20130731  

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 7/1/13 to 7/31/13.

Vanderhoff, Alex

296

Green Machine Florida Canyon Hourly Data  

SciTech Connect

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 6/1/13 to 6/30/13

Vanderhoff, Alex

2013-07-15

297

20130416_Green Machine Florida Canyon Hourly Data  

SciTech Connect

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 4/16/13.

Vanderhoff, Alex

2013-04-24

298

Green Machine Florida Canyon Hourly Data 20130731  

SciTech Connect

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 7/1/13 to 7/31/13.

Vanderhoff, Alex

2013-08-30

299

20130416_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 4/16/13.

Vanderhoff, Alex

300

20140430_Green Machine Florida Canyon Hourly Data  

SciTech Connect

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.

Thibedeau, Joe

2014-05-05

301

Evolution of surface gravity waves over a submarine canyon  

E-print Network

The effects of a submarine canyon on the propagation of ocean surface waves are examined with a three-dimensional coupled-mode model for wave propagation over steep topography. Whereas the classical geometrical optics approximation predicts an abrupt transition from complete transmission at small incidence angles to no transmission at large angles, the full model predicts a more gradual transition with partial reflection/transmission that is sensitive to the canyon geometry and controlled by evanescent modes for small incidence angles and relatively short waves. Model results for large incidence angles are compared with data from directional wave buoys deployed around the rim and over Scripps Canyon, near San Diego, California, during the Nearshore Canyon Experiment (NCEX). Wave heights are observed to decay across the canyon by about a factor 5 over a distance shorter than a wavelength. Yet, a spectral refraction model predicts an even larger reduction by about a factor 10, because low frequency components c...

Magne, R; Herbers, T H C; Ardhuin, F; O'Reilly, W C; Rey, V; Magne, Rudy; Belibassakis, Kostas; Herbers, Thomas H. C.; Ardhuin, Fabrice; Reilly, William C. O'; Rey, Vincent

2006-01-01

302

Pleistocene entrenched valley/canyon systems, Gulf of Mexico  

SciTech Connect

The Mississippi Submarine Canyon is the seaward extension of the late Wisconsin entrenched alluvial valley. Geophysical and geologic data provide evidence for the continuity of the Mississippi entrenched valley, the Timbalier channel, and the submarine canyon. The Mississippi entrenched valley/canyon system is one of several systems recognized in the Pleistocene section of offshore Louisiana. Most of these systems were produced by the ancestral Mississippi River. They typically exhibit a three-gradient profile with their maximum erosional relief at the preexisting shelf margin. The canyons extend onto the pre-existing shelf for 20 to 50 mi, with erosion commonly exceeding 1000 ft. All of these systems delivered large quantities of sediment to the Pleistocene slope and abyssal plain. The fan deposits are the products of sediment passing through and being removed from the entrenched valley/canyon systems.

Steffens, G.S.

1986-09-01

303

North Atlantic slope and canyon study. Volume 2. Final report  

SciTech Connect

A field program to investigate the currents and sediment transport along the outershelf and upper slope along the southern flank of Georges Bank was conducted between 1980 and 1984. A major part of the field experiment was conducted in Lydonia Canyon, a large submarine canyon which cuts northward about 20 km into the continental shelf from the shelfbreak. A smaller experiment was conducted in Oceanographer Canyon to compare the currents in these two major canyons. Long-term current observations were made at 20 locations in or adjacent to Lydonia Canyon, and at 9 stations on the continental slope. Detailed semi-synoptic hydrographic observations were made on 9 cruises. The currents associated with Gulf Stream warm core rings (WCR's) strongly affect the flow along the outer shelf and upper slope; eastward currents in excess of 75cm/s were associated with WCR's.

Butman, B.

1986-12-01

304

The Black Canyon of the Gunnison: Today and Yesterday  

USGS Publications Warehouse

Since the early visit of Captain John William Gunnison in the middle of the last century, the Black Canyon of the Gunnison has stirred mixed apprehension and wonder in the hearts of its viewers. It ranks high among the more awesome gorges of North America. Many great western canyons are as well remembered for their brightly colored walls as for their airy depths. Not so the Black Canyon. Though it is assuredly not black, the dark-gray tones of its walls and the hazy shadows of its gloomy depths join together to make its name well deserved. Its name conveys an impression, not a picture. After the first emotional impact of the canyon, the same questions come to the minds of most reflective viewers and in about the following order: How deep is the Black Canyon, how wide, how does it compare with other canyons, what are the rocks, how did it form, and how long did it take? Several western canyons exceed the Black Canyon in overall size. Some are longer; some are deeper; some are narrower; and a few have walls as steep. But no other canyon in North American combines the depth, narrowness, sheerness, and somber countenance of the Black Canyon. In many places the Black Canyon is as deep as it is wide. Between The Narrows and Chasm View in the Black Canyon of the Gunnison National Monument (fig. 15) it is much deeper than wide. Average depth in the monument is about 2,000 feet, ranging from a maximum of about 2,700 feet, north of Warner Point (which also is the greatest depth anywhere in the canyon), to a minimum of about 1,750 feet at The Narrows. The stretch of canyon between Pulpit Rock and Chasm View, including The Narrows, though the shallowest in the monument, is also the narrowest, has some of the steepest walls, and is, therefore, among the most impressive segments of the canyon (fig. 3). Profiles of several well-known western canyons are shown in figure 1. Deepest of these by far is Hells Canyon of the Snake, on the Idaho-Oregon border. Clearly, it dwarfs the Black Canyon in the immensity of its void, though its flaring walls lack the alarming verticality of the Black Canyon. Arizona's Grand Canyon of the Colorado is acknowledged as the greatest of them all; it is not as deep as Hells Canyon, but it is wider, longer, more rugged, and far more colorful. Its depth is two to three times that of the Black Canyon. Zion Canyon, Utah, combines depth, sheerness, serenity, and color in a chasm that ranges from capacious to extremely narrow. Its Narrows have a depth-to-width ratio unmatched by any other major American canyon. California's Yosemite Valley, in a setting of sylvan verdure, is unique among the gorges shown in profile in figure 1 in being the only glacial trough; its monolithic walls bear witness to the abrasive power of moving ice. Few cliffs in the world match the splendor of its El Capitan. Lodore Canyon, on the Green River in Dinosaur National Monument, Colorado, is best known, perhaps, for its noisy splashy rapids, first made famous by John Wesley Powell. Lodore Canyon also features towering cliffs of deep-red quartzite. Grand Canyon of the Yellowstone River, Wyoming, is noted for its great waterfalls, dashing river, and bright coloration. The Royal Gorge of the Arkansas River, Colorado, features the 'world's highest suspension bridge'. The profiles shown in figure 1 afford some basis for comparing one canyon with another. They cannot abstract in two dimensions the overall impression that each canyon makes. Color, vegetation, outcrop habit, vantage point, season of year, length of visit - even the roar of the river or lack thereof - all contribute to this highly personal effect. For a river of its size, the Gunnison has an unusually steep gradient through the Black Canyon. The river falls about 2,150 feet from the head of the canyon at Sapinero to the mouth at its junction with North Fork - a distance of about 50 miles and an average rate of fall of about 43 feet per mile. By comparison, the Green

Hansen, Wallace R.

1965-01-01

305

Active geologic processes in Barrow Canyon, northeast Chukchi Sea  

USGS Publications Warehouse

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

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

1982-01-01

306

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

307

Episodes of fluvial and volcanic activity in Mangala Valles, Mars  

NASA Astrophysics Data System (ADS)

A new mapping-based study of the 900-km-long Mangala Valles outflow system was motivated by the availability of new high-resolution images and continued debates about the roles of water and lava in outflow channels on Mars. This study uses photogeologic analysis, geomorphic surface mapping, cratering statistics, and relative stratigraphy. Results show that Mangala Valles underwent at least two episodes of fluvial activity and at least three episodes of volcanic activity during the Late Amazonian. The occurrence of scoured bedrock at the base of the mapped stratigraphy, in addition to evidence provided by crater retention ages, suggests that fluvial activity preceded the deposition of two of the volcanic units. Crater counts performed at 30 locations throughout the area have allowed us to construct the following timeline: (1) formation of Noachian Highlands and possible initial flooding event(s) before ?1 Ga, (2) emplacement of Tharsis lava flows in the valley from ?700 to 1000 Ma, (3) a megaflooding event at ?700-800 Ma sourced from Mangala Fossa, (4) valley fill by a sequence of lava flows sourced from Mangala Fossa ?400-500 Ma, (5) another megaflooding event from ?400 Ma, (6) a final phase of volcanism sourced from Mangala Fossa ?300-350 Ma, and (7) emplacement of eolian sedimentary deposits in the northern portion of the valley ?300 Ma. These results are consistent with alternating episodes of aqueous flooding and volcanism in the valles. This pattern of geologic activity is similar to that of other outflow systems, such as Kasei Valles, suggesting that there is a recurring, and perhaps coupled, nature of these processes on Mars.

Keske, Amber L.; Hamilton, Christopher W.; McEwen, Alfred S.; Daubar, Ingrid J.

2015-01-01

308

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.

309

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

E-print Network

I ;'. 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' INTRODUCTION 100,000,.... COLORAOQ RIVER NEAR GRAND CANYON (PHANTOM RANCHi The completion of Glen Canyon Dam

310

A submarine canyon as the cause of a mud volcano Liuchieuyu Island in Taiwan  

E-print Network

A submarine canyon as the cause of a mud volcano Ð Liuchieuyu Island in Taiwan J. Chowa,*, J, we also discuss the relationship between a nearby submarine canyon (Kaoping Submarine Canyon¯ection; Submarine canyon; Mud volcano 1. Introduction In the early Pliocene, the paleoenvironment of the offshore

Lin, Andrew Tien-Shun

311

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

312

Tidal motions and tidally induced fluxes through La Línea submarine canyon, western Alboran sea  

Microsoft Academic Search

Detailed observations from two mooring lines deployed in La Línea submarine canyon, western Alboran Sea, are presented. This is a narrow canyon in the sense that its width is always less than the internal radius of deformation. Tidal currents within the canyon are polarized in the along-canyon direction according to its narrow nature. They have considerable amplitude (values of around

Jesús García Lafuente; Tarek Sarhan; Manuel Vargas; Juan M. Vargas; Francisco Plaza

1999-01-01

313

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

314

Mars  

NSDL National Science Digital Library

This NASA (National Aeronautics and Space Administration) planet profile provides data and images of the planet Mars. These data include planet size, orbit facts, distance from the Sun, rotation and revolution times, temperature, atmospheric composition, density, surface materials and albedo. Images with descriptions include surface features such as canyons, volcanoes, Viking 1 and 2 landing sites, the South Pole, plateaus, the Schiaparelli Crater, Amazonis Plains, Cerberus Crater, Valles Marineris, Chasma, Olympis Mons, and images of Mars two moons Phobos and Deimos. Images were taken by the Viking 1 and 2 Landers and the Viking Orbiter Spacecraft.

315

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

316

Inner gorge-slot canyon system produced by repeated stream incision (eastern Alps): Significance for development of bedrock canyons  

NASA Astrophysics Data System (ADS)

Many inner bedrock gorges of the Alps show abrupt downstream changes in gorge width, as well as channel type and gradient, as a result of epigenetic incision of slot canyons. Many slot canyons also are associated with older gorge reaches filled with Quaternary deposits. The age of slot canyons and inner bedrock gorges, however, commonly is difficult to constrain. For the inner-bedrock gorge system of the Steinberger Ache catchment (eastern Alps), active slot canyons as well as older, abandoned gorge reaches filled with upper Würmian proglacial deposits record three phases of gorge development and slot-canyon incision. A 234U/230Th age of cement of 29.7 ± 1.8 ka in fluvial conglomerates onlapping the flank of an inner gorge fits with late Würmian valley-bottom aggradation shortly before pleniglacial conditions; in addition, the age indicates that at least the corresponding canyon reach must be older. During advance of ice streams in the buildup of the Last Glacial Maximum (LGM), the catchment was blocked, and a proglacial lake formed. Bedrock gorges submerged in that lake were filled with fluviolacustrine deposits. During the LGM, the entire catchment was overridden by ice. During post-glacial reincision, streams largely found again their preexisting inner bedrock canyons. In some areas, however, the former stream course was 'missed', and a slot canyon formed. The distribution of Pleistocene deposits, the patterns of canyon incision, and the mentioned U/Th cementation age, however, together record a further discrete phase of base-level rise and stream incision well before the LGM. The present course of Steinberger Ache and its tributaries is a patchwork of (1) slot canyons incised during post-glacial incision; (2) vestiges of slot canyons cut upon an earlier (middle to late Würmian?) cycle of base-level rise and fall; (3) reactivated reaches up to ~ 200 m in width of inner bedrock gorge that are watershed at present, and more than at least ~ 30 ka in age; and (4) abandoned, sediment-filled reaches of bedrock canyons that also must be older than 30 ka and that are exposed alongside the active streams. 'Multi-cyclic' bedrock canyon systems composed of reaches of markedly different ages may be common in mountain ranges subject to glaciations and/or mass wasting.

Sanders, Diethard; Wischounig, Lukas; Gruber, Alfred; Ostermann, Marc

2014-06-01

317

Regional impact of submarine canyons during seasonal upwelling  

NASA Astrophysics Data System (ADS)

numerical model of the northern California Current System along the coasts of Washington and British Columbia is used to quantify the impact of submarine canyons on upwelling from the continental slope onto the shelf. Comparisons with an extensive set of observations show that the model adequately represents the seasonal development of near-bottom density, as well as along-shelf currents that are critical in governing shelf-slope exchange. Additional model runs with simplified coastlines and bathymetry are used to isolate the effects of submarine canyons. Near submarine canyons, equatorward flow over the outer shelf is correlated with dense water at canyon heads and subsequent formation of closed cyclonic eddies, which are both associated with cross-shelf ageostrophic forces. Lagrangian particles tracked from the slope to midshelf show that canyons are associated with upwelling from depths of ˜140-260 m. Source depths for upwelling are shallower than 150 m at locations away from canyons and in a model run with bathymetry that is uniform in the along-shelf direction. Water upwelled through canyons is more likely to be found near the bottom over the shelf. Onshore fluxes of relatively saline water through submarine canyons are large enough to increase volume-averaged salinity over the shelf by 0.1-0.2 psu during the early part of the upwelling season. The nitrate input from the slope to the Washington shelf associated with canyons is estimated to be 30-60% of that upwelled to the euphotic zone by local wind-driven upwelling.

Connolly, Thomas P.; Hickey, Barbara M.

2014-02-01

318

Report Summary, Final Hells Canyon Environmental Investigation.  

SciTech Connect

The Northwest Electric Power Planning and Conservation Act of 1980 provided for the establishment of a Regional Power Planning Council (Regional Council) and mandated the development of a Columbia River Basin Fish and Wildlife Program (F&W Program). The F&W Program was adopted by the Regional Council in November 1982. and is intended to mitigate fish and wildlife losses resulting from the development of hydroelectric dams on the Columbia and Snake Rivers. One element of the FLW Program is the Water Budget. It calls for additional flows in the Columbia and Snake Rivers between April 15 and June 15 to improve the survival of juvenile salmon and steelhead migrating downstream. The Snake River's contribution to the Water Budget is 20,000 cubic feet per second-months (A volume of water equal to a flow of 20.000 cubic feet per second, 24 hours per day, for a period of a month) over and above water that would normally flow for power production. The water for the Water Budget would come out of Idaho Power Company's (IPCo) Hells Canyon Complex and the Corps of Engineers' (Corps) Dvorshak Reservoir. IPCo's Hells Canyon Complex consists of three dams, Brownlee, Oxbow, and Hells Canyon. Brownlee, at the upstream end, contains a large reservoir and controls flow to the lower dams. IPCo's participation in the Water Budget could affect the level of the Brownlee Reservoir and flows downstream of the Hells Canyon Complex on the Snake River. In light of this, Bonneville Power Administration (BPA) and IPCo contracted with the consulting firm of CH2!4 Hill to study the potential changes that could occur to the environment. The Environmental Investigation (EI) takes into account concerns that were expressed by the public at a series of public meetings held in the Snake River area during June 1983 and again during September 1984. Existing information and consultations with agencies which have management responsibilities in the project area formed the basis for the data used in the EI. This document summarizes the findings of the final EI in the following areas: (1) natural features, water use, and air and water quality; (2) fish, wildlife, and vegetation; (3) land use, recreation, and aesthetics; and (4) historical and archaeological resources. The EI provides information to be used by IPCo as they assess the effect on the system operations (power and nonpower) resulting from Water Budget participation. BPA and IPCo are continuing to discuss the prospects for IPCo's involvement in implementation of the Water Budget on the Snake River. When IPCo reaches a decision on whether and to what extent it wishes to participate in a Water Budget agreement with BPA, the proposed agreement will be subject to analysis under the National Environmental Policy Act (NEPA). That analysis will consider alternatives, significance of impacts to the environment, and mitigative measures.

United States. Bonneville Power Administration.

1985-01-01

319

Environmental Magnetism of mid-Pleistocene Lacustrine Sediments of the Valles Caldera, New Mexico  

Microsoft Academic Search

Rock magnetic measurements are applied to almost 80 m of lacustrine sediment (VC-3) to augment independent means of interpreting the environmental conditions of a mid-Pleistocene lake in the Valle Grande of the Valles Caldera, northern New Mexico. An age model for the core is pinned to an Ar\\/Ar age determination of 552 ± 3 ka for a sanidine bearing ash

L. L. Hurley; J. W. Geissman; P. Fawcett; W. Tim; F. Goff

2007-01-01

320

Fossil Woodwardia virginica Foliage From the Middle Miocene Yakima Canyon  

NSDL National Science Digital Library

Fossil Woodwardia virginica foliage from the middle Miocene Yakima Canyon flora of central Washington State, USA. Vegetative and fertile features of this fossil are remarkably similar to those of the modern ""Virginia chain fern"" of the Atlantic coastal region, USA.

Kathleen B. Pigg (Arizona State University;Department of Plant Biology ADR;POSTAL)

2004-03-09

321

37. PRATER CANYON AND CIVILIAN CONSERVATION CORPS CAMP SITE FROM ...  

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

37. PRATER CANYON AND CIVILIAN CONSERVATION CORPS CAMP SITE FROM PRATER GRADE, FACING E. SAME CAMERA LOCATION AS No. 35 AND No. 36. - Mesa Verde National Park Main Entrance Road, Cortez, Montezuma County, CO

322

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

323

A view in Lapwai Canyon at Milepost 18 of the ...  

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

A view in Lapwai Canyon at Milepost 18 of the grade cut through basalt - Camas Prairie Railroad, Second Subdivision, From Spalding in Nez Perce County, through Lewis County, to Grangeville in Idaho County, Spalding, Nez Perce County, ID

324

H CANYON PROCESSING IN CORRELATION WITH FH ANALYTICAL LABS  

SciTech Connect

Management of radioactive chemical waste can be a complicated business. H Canyon and F/H Analytical Labs are two facilities present at the Savannah River Site in Aiken, SC that are at the forefront. In fact H Canyon is the only large-scale radiochemical processing facility in the United States and this processing is only enhanced by the aid given from F/H Analytical Labs. As H Canyon processes incoming materials, F/H Labs provide support through a variety of chemical analyses. Necessary checks of the chemical makeup, processing, and accountability of the samples taken from H Canyon process tanks are performed at the labs along with further checks on waste leaving the canyon after processing. Used nuclear material taken in by the canyon is actually not waste. Only a small portion of the radioactive material itself is actually consumed in nuclear reactors. As a result various radioactive elements such as Uranium, Plutonium and Neptunium are commonly found in waste and may be useful to recover. Specific processing is needed to allow for separation of these products from the waste. This is H Canyon's specialty. Furthermore, H Canyon has the capacity to initiate the process for weapons-grade nuclear material to be converted into nuclear fuel. This is one of the main campaigns being set up for the fall of 2012. Once usable material is separated and purified of impurities such as fission products, it can be converted to an oxide and ultimately turned into commercial fuel. The processing of weapons-grade material for commercial fuel is important in the necessary disposition of plutonium. Another processing campaign to start in the fall in H Canyon involves the reprocessing of used nuclear fuel for disposal in improved containment units. The importance of this campaign involves the proper disposal of nuclear waste in order to ensure the safety and well-being of future generations and the environment. As processing proceeds in the fall, H Canyon will have a substantial number of samples being sent to F/H Labs. All analyses of these samples are imperative to safe and efficient processing. The important campaigns to occur would be impossible without feedback from analyses such as chemical makeup of solutions, concentrations of dissolution acids and nuclear material, as well as nuclear isotopic data. The necessity of analysis for radiochemical processing is evident. Processing devoid of F/H Lab's feedback would go against the ideals of a safety-conscious and highly accomplished processing facility such as H Canyon.

Weinheimer, E.

2012-08-06

325

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

326

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.

327

A Street Canyon Model Intercomparison in Florence, Italy  

Microsoft Academic Search

Assessing air quality in street canyons is a crucial concern, as the highest pollution levels and threshold exceedances are\\u000a usually experienced within this kind of urban streets. A brief overview based on experimental studies and modelling techniques\\u000a undertaken in literature is presented, including characteristic features affecting wind flow and pollutant dispersion within\\u000a street canyons. In this work, a numerical street

Giovanni Gualtieri

2010-01-01

328

Canyon dynamics and related sedimentary impacts off western Portugal  

NASA Astrophysics Data System (ADS)

Submarine canyons are areas of increased exchanges between the continental shelf and the deep ocean. We present preliminary results from a multidisciplinary research focussing the dynamics of several canyon systems that occur along the Portuguese continental margin. The research is being conducted in the framework of EU project Eurostrataform and aims to understand the dominant aspects of the interaction between shelf/slope flows and canyons and to relate those aspects with the exportation of sediments from the shelf. The present work is intended to complement results from previous projects that were focussed on the quasi-inertial dynamics of the Portuguese canyon systems. Three contrasting systems are studied: (1) the Nazaré Canyon, a narrow and deep canyon which completely cuts the shelf, with no local riverine sources; (2) the Setubal-Lisbon canyon system, located in an area of complex topography and coastline configuration, with local riverine sources (Tagus and Sado rivers) and (3) the Oporto canyon, which is restricted to the outer shelf and affected by a major riverine source (Douro river). The ongoing program of observations includes multidisciplinary surveys (CTD, ADCP, suspended particle matter measurements, shallow seismic) and both long-term and short-term currentmeter moorings. The observations will cover both the summer upwelling regime as well as the highly energetic winter conditions. Process studies will combine observations and numerical modeling tools through the use of MOCASSIM system, which is presently being developed at Instituto Hidrografico. The system integrates several numerical models and is intended to characterise the wave and current conditions over the study areas.

Vitorino, J.; Oliveira, A.; Silva, R.; Quaresma, L.; Marreiros, R.

2003-04-01

329

Continuous monitoring of carbon monoxide in a deep street canyon  

Microsoft Academic Search

The results of a 1-week continuous monitoring campaign of carbon monoxide in a deep street canyon in the city of Naples are reported. CO was selected as a passive pollutant emitted by vehicle exhausts. The geometry of the canyon is: width W=5.8m and height H=33m (aspect ratio AR=H\\/W=5.7). The monitoring campaign was carried out from 14 to 20 June 2006.

Fabio Murena; Giuseppe Favale

2007-01-01

330

Cenozoic Landscape Evolution of the Grand Canyon Region, Arizona  

E-print Network

CHAPTER 1: Quantifying the Evolution of Grand Canyon Topography with Thermochronology and Numerical Modeling Chapter Summary 1 1. Introduction 2 2. Background and Approach 4 2.1 Geologic Setting... 4 2.2 End Member Erosion Models 6 2.3 Approach and Methodology 7 2.3.1 Isotherm Deflection 7 2.3.2 Numerical Modeling 8 2.3.3 Apatite (U-Th)/He Thermochronology 9 3. Synthetic Canyon...

Lee, John

2008-02-26

331

Safety Evaluation for Packaging (onsite) T Plant Canyon Items  

SciTech Connect

This safety evaluation for packaging (SEP) evaluates and documents the ability to safely ship mostly unique inventories of miscellaneous T Plant canyon waste items (T-P Items) encountered during the canyon deck clean off campaign. In addition, this SEP addresses contaminated items and material that may be shipped in a strong tight package (STP). The shipments meet the criteria for onsite shipments as specified by Fluor Hanford in HNF-PRO-154, Responsibilities and Procedures for all Hazardous Material Shipments.

OBRIEN, J.H.

2000-07-14

332

Microthermometry of fluid inclusions from the VC-1 core hole in Valles Caldera, New Mexico  

NASA Astrophysics Data System (ADS)

Fluid inclusions in vein quartz and calcite from core samples of the VC-1 hole were studied with microscope heating/freezing and crushing stages. All samples originate from hydrothermally altered Paleozoic rocks predating formation of the Jemez Mountains volcanic field and Valles caldera. Most homogenization temperatures (Th) of the liquid-rich inclusions are above the present well temperature, but some Th of primary inclusions from 515 m and those of secondary inclusions from 723 m fit the present well temperature curve measured 10 months after completion of the well. The maximum temperature recorded by the primary inclusions is 275°C from hydrothermal quartz in the Sandia Formation at 811-m depth. The total range of Th for samples from several depths (90°C) indicates cooling from the maximum temperature. The salinity of fluid inclusions in hydrothermal quartz and calcite is generally low, <1 wt % NaCl eq. High-salinity fluid, up to 5 wt % NaCl eq, has been found in several calcite veins from the lower part of the Madera Limestone. The salinity decreases with decrease of Th of the secondary inclusions, and that with lowest Th at the lower part of the Madera Limestone is similar to those from the other depths. These data show that early hot water circulation system involved several types of fluid, whereas the later one was a homogeneous fluid. The salinity of fluid inclusions in detrital quartz (presumably inherited inclusions) is higher than that in hydrothermal minerals. Some of these inclusions show extraordinary low temperatures of final melting point of ice (about -40°C), suggesting that a CaCl2 component is present. CO2 contents in fluid inclusions were estimated by the bubble behavior on crushing. Crushing results indicate that CO2 content of the early fluid is ?0.35 wt %, and that of the later fluid is ˜0.2-0.3 wt %. Geothermal fluid trapped in the fluid inclusions representing the present temperature regime is comparable in composition to those from the Baca geothermal field inside the caldera and to those from hot springs in San Diego Canyon.

Sasada, Masakatsu

1988-06-01

333

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

334

Transition from partly standing to progressive internal tides in Monterey Submarine Canyon  

NASA Astrophysics Data System (ADS)

Monterey Submarine Canyon is a large, sinuous canyon off the coast of California, the upper reaches of which were the subject of an internal tide observational program using moored profilers and upward-looking moored ADCPs. The mooring observations measured a near-surface stratification change in the upper canyon, likely caused by a seasonal shift in the prevailing wind that favoured coastal upwelling. This change in near-surface stratification caused a transition in the behaviour of the internal tide in the upper canyon from a partly standing wave during pre-upwelling conditions to a progressive wave during upwelling conditions. Using a numerical model, we present evidence that either a partly standing or a progressive internal tide can be simulated in the canyon, simply by changing the initial stratification conditions in accordance with the observations. The mechanism driving the transition is a dependence of down-canyon (supercritical) internal tide reflection from the canyon floor and walls on the depth of maximum stratification. During pre-upwelling conditions, the main pycnocline extends down to 200 m (below the canyon rim) resulting in increased supercritical reflection of the up-canyon propagating internal tide back down the canyon. The large up-canyon and smaller down-canyon progressive waves are the two components of the partly standing wave. During upwelling conditions, the pycnocline shallows to the upper 50 m of the watercolumn (above the canyon rim) resulting in decreased supercritical reflection and allowing the up-canyon progressive wave to dominate.

Hall, Rob A.; Alford, Matthew H.; Carter, Glenn S.; Gregg, Michael C.; Lien, Ren-Chieh; Wain, Danielle J.; Zhao, Zhongxiang

2014-06-01

335

Stable isotope evidence for depositional cycles and diagenetic patterns in Brushy Canyon and Cherry Canyon formations, Delaware basin, west Texas  

SciTech Connect

A stable isotope study on two cores from the Brushy Canyon Formation and three cores from the Cherry Canyon Formation of the Delaware basin reveal distinct delta/sup 18/O isotopic differences in the carbonate matrix of these two clastic facies. The delta/sup 18/O isotopic values in the two Brushy Canyon cores are similar, regardless of whether the cores are from an overbank or channel part of the deep-water fan complex. The three Cherry Canyon cores are considerably more enriched in delta/sup 18/O than the Brushy Canyon cores, i.e., some values exceed +100 per mil relative to PDB. The delta/sup 18/O record of the three cores appears to correlate regionally with both isotopic composition and the geophysical logs. The extremely enriched delta/sup 18/O values (> +30 per mil) in the Cherry Canyon directly correspond to the fine to medium siltstones. The fine to medium sandstones represent a relatively depleted delta/sup 18/O isotopic signal of less than +30 per mil. The large delta/sup 18/O contrast between the Brushy Canyon and Cherry Canyon basinal clastics suggests that changes in sea level, combined with possible wind-blown clastic and evaporitic materials from back-reef lagoonal environments, could enhance the distinct isotopic differences of the two clastic facies. Although diagenesis is part of the isotopic signal of the carbonate matrix of both basinal clastic facies, the effects of diagenesis have not totally eliminated the primary isotopic signal due to the depositional processes of the two clastic facies.

Mucciarone, D.A.; Williams, D.F.; Bouma, A.H.

1986-05-01

336

The buried Afiq Canyon (eastern Mediterranean, Israel): a case study of a Tertiary submarine canyon exposed in Late Messinian times  

Microsoft Academic Search

The Afiq submarine canyon was one of a series of canyons initially incised in a drowned shelf edge and slope of the eastern Mediterranean margins in early Oligocene times (P19 zone). During most of the Early Miocene submarine erosion or non-deposition prevailed. This was followed by deposition of pelagic marls and debris flows in early Middle Miocene (N8) times. Large-scale

Y. Druckman; B. Buchbinder; G. M. Martinotti; R. Siman Tov; P. Aharon

1995-01-01

337

SRTM Anaglyph: Pinon Canyon region, Colorado  

NASA Technical Reports Server (NTRS)

Erosional features are prominent in this view of southern Colorado taken by the Shuttle Radar Topography Mission (SRTM). The area covers about 20,000square kilometers and is located about 50 kilometers south of Pueblo, Colorado. The prominent mountains near the left edge of the image are the Spanish Peaks, remnants of a 20 million year old volcano. Rising 2,100 meters (7,000 feet) above the plains to the east, these igneous rock formations with intrusions of eroded sedimentary rock historically served as guiding landmarks for travelers on the Mountain Branch of the Santa Fe Trail.

Near the center of the image is the Pinon Canyon Maneuver Site, a training area for soldiers of the U.S. Army from nearby Fort Carson. The site supports a diverse ecosystem with large numbers of big and small game, fisheries, non-game wildlife, forest, range land and mineral resources. It is bounded on the east by the dramatic topography of the Purgatoire River Canyon, a 100 meter (328 feet) deep scenic red canyon with flowing streams, sandstone formations and exposed geologic processes.

This anaglyph was produced by first shading a preliminary SRTM elevation model. The stereoscopic effect was then created by generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.

Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR)that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense, and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

Size: 177.8 x 111.3 kilometers ( 110.5 x 69.2 miles) Location: 37.5 deg. North lat., 104 deg. West lon. Orientation: North toward the top Original Data Resolution: SRTM 1 arcsecond (30 meters or 99 feet) Image Data: Shaded and colored SRTM elevation model

2001-01-01

338

Metamorphic signature of the Gneiss Canyon Shear Zone, Lower Granite Gorge, Grand Canyon, Arizona  

SciTech Connect

The Proterozoic orogen in Arizona consists of structural blocks separated by NE trending shear zones. The Gneiss Canyon Shear Zone (GCSZ) is important because it appears to define in part the boundary between the amphibolite facies Yavapai Province and the granulite facies Mojave Province. An early NW striking foliation is clearly visible in many samples from the Lower Granite Gorge (LGG). In Travertine Canyon, east of the GCSZ, pelitic schists contain And-Sil-Crd-Bi and Gar-Sil-Sta-Bi. Mafic rocks exhibit complex phase relations between cummingtonite, anthophyllite, gedrite, garnet, and cordierite. The coexistence of cordierite-cummingtonite is indicative of low pressure metamorphism. Microprobe analyses of garnets reveal prograde growth zoning profiles. Temperature and pressure estimates of peak metamorphism are 550--600 C and 3 kb. Just east of the GCSZ, pelitic assemblages contain Gar-Bi [+-] Sil [+-] Mus, and garnet zoning profiles are flat in the cores. In Spencer Canyon, west of the GCSZ, samples commonly contain Gar-Bi-Sil-Crd, and in many samples cordierite is being replaced by sillimanite. Thermobarometric calculations yield temperature and pressure estimates of 650 C and 3.5 kb. Mineral assemblages and quantitative thermobarometry suggest higher peak metamorphic temperature west of the GCSZ but relatively constant pressures across the LGG. On the east side of the GCSZ, temperatures increase toward the Shear Zone, probably due to the presence of extensive dikes, pods, and veins of variably deformed granite. Peak mineral assemblages are syntectonic with respect to the NE-striking GCSZ fabric. If a suture exists in the LGG, the GCSZ fabrics apparently reflect post-accretionary tectonism, with accretion occurring prior to the peak of metamorphism.

Robinson, K.; Williams, M.L. (Univ. of Massachusetts, Amherst, MA (United States). Dept. of Geology and Geography)

1992-01-01

339

Regional depositional history of the Miocene-Pleistocene Louisiana Slope, Green Canyon and Mississippi Canyon  

SciTech Connect

A regional sequence-stratigraphic analysis was recently completed for the Tertiary slope sediments in Green Canyon, Ewing Bank, and Mississippi Canyon to provide a chronostratigraphic framework for basin reconstructions and predict lithofacies distributions of reservoir and seal rocks. Sixteen third-order sequences of lowstand deep-water deposits were interpreted for the middle Miocene-Pleistocene section. Thirty regional lithofacies maps were made of predominantly lowstand deposits showing the distribution of shale and sand-prone sediments, slumping, channel levee systems, and fan lobes based on distinctive seismic reflection and well log patterns. These maps were combined with isochrons of selected sequences to identify depositional fairways, depocenters, and paleosalt positions that constantly changed through time. Depositional trends were principally north to south but were also observed to be east-west as salt modified the gradient on the gently dipping slope. In some cases, the structural and stratigraphic trends could be projected under allochthonous tabular salt. Miocene channel and fan lobe sands were found concentrated on the middle-lower paleoslope across the study area. The sedimentation rate doubled (0.7 m/1000 yr) in the early-middle Pliocene, which caused large-scale salt movements and trapped sand-prone turbidites along the upper-middle slope. A four-fold decrease in sediment influx during the late Pliocene-early Pleistocene produced a stacked condensed section of four sequences over the eastern Louisiana slope. A return to rapid sedimentation (up to 2.1 m/1000 yr.) during the Pleistocene reactivated salt movements and depocenters in the Green Canyon, Ewing Bank, and Mississippi Trough areas.

Risch, D.L.; Chowdhury, A.N.; Hannan, A.E. [Geco-Prakla, Houston, TX (United States)

1994-09-01

340

76 FR 47237 - Notice of Public Meeting for the Glen Canyon Dam Adaptive Management Work Group Federal Advisory...  

Federal Register 2010, 2011, 2012, 2013

...Notice of Public Meeting for the Glen Canyon Dam Adaptive Management Work Group Federal Advisory...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...

2011-08-04

341

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

Federal Register 2010, 2011, 2012, 2013

...Proposed Supplementary Rules on Public Land in Water Canyon, Humboldt County, NV AGENCY...and resources on public land within the Water Canyon Recreation Area. These proposed...restrictions included within the decisions of the Water Canyon Recreation Area Management...

2012-11-09

342

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

E-print Network

failure inventory map with spring locations in Parrish and Centerville Canyons. Figure 17. Site C-5, Centerville Canyon. Figure 18. Site C-6, Centerville Canyon. Figure 19. Site F-2, Ford Canyon. Figure 20. Site F-1, Ford Canyon . Figure 21. Outcrop...= Farmington Canyon Complex (from Ala, 1990). 18 114 112 1 10 44 42 40 38 t ktoNr4 1 . r) I 'I 1 1 4 I V !\\ "" rh, , I +aaa tah F'autt tp4H0 I 'r t3 I I N. Utah Hlghtattu I 44, 4r ac M. I I trrlllar0 ~l 0 rhrust 4-&. 4 4 +&" a...

Skelton, Robyn Kaye

1991-01-01

343

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

344

Is the Valles caldera entering a new cycle of activity?  

SciTech Connect

The Valles caldera formed during two major rhyolitic ignimbrite eruptive episodes (the Bandelier Tuff) at 1.61 and 1.22 Ma, after some 12 m.y. of activity in the Jemez Mountains volcanic field, New Mexico. Several subsequent eruptions between 1.22 and 0.52 Ma produced dominantly high-silica rhyolite lava domes and tephras within the caldera. These were followed by a dormancy of 0.46 m.y. prior to the most recent intracaldera activity, the longest hiatus since the inception of the Bandelier magma system at approximately 1.8 Ma. The youngest volcanic activity at approximately 60 ka produced the SW moat rhyolites, a series of lavas and tuffs that display abundant petrologic evidence of being newly generated melts. Petrographic textures conform closely to published predictions for silicic magmas generated by intrusion of basaltic magma into continental crust. The Valles caldera may currently be the site of renewed silicic magma generation, induced by intrusion of mafic magma at depth. Recent seismic investigations revealed the presence of a large low-velocity anomaly in the lower crust beneath the caldera. The generally aseismic character of the caldera, despite abundant regional seismicity, may be attributed to a heated crustal column, the local effect of 13 m.y. of magmatism and emplacement of mid-crustal plutons. 24 refs., 3 figs.

Wolff, J.A. [Univ. of Texas, Arlington, TX (United States)] [Univ. of Texas, Arlington, TX (United States); Gardner, J.N. [Los Alamos National Lab., NM (United States)] [Los Alamos National Lab., NM (United States)

1995-05-01

345

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

346

Formation of the Grand Canyon 5 to 6 million years ago through integration of older palaeocanyons  

NASA Astrophysics Data System (ADS)

The timing of formation of the Grand Canyon, USA, is vigorously debated. In one view, most of the canyon was carved by the Colorado River relatively recently, in the past 5-6 million years. Alternatively, the Grand Canyon could have been cut by precursor rivers in the same location and to within about 200 m of its modern depth as early as 70-55 million years ago. Here we investigate the time of formation of four out of five segments of the Grand Canyon, using apatite fission-track dating, track-length measurements and apatite helium dating: if any segment is young, the old canyon hypothesis is falsified. We reconstruct the thermal histories of samples taken from the modern canyon base and the adjacent canyon rim 1,500 m above, to constrain when the rocks cooled as a result of canyon incision. We find that two of the three middle segments, the Hurricane segment and the Eastern Grand Canyon, formed between 70 and 50 million years ago and between 25 and 15 million years ago, respectively. However, the two end segments, the Marble Canyon and the Westernmost Grand Canyon, are both young and were carved in the past 5-6 million years. Thus, although parts of the canyon are old, we conclude that the integration of the Colorado River through older palaeocanyons carved the Grand Canyon, beginning 5-6 million years ago.

Karlstrom, Karl E.; Lee, John P.; Kelley, Shari A.; Crow, Ryan S.; Crossey, Laura J.; Young, Richard A.; Lazear, Greg; Beard, L. Sue; Ricketts, Jason W.; Fox, Matthew; Shuster, David L.

2014-03-01

347

BotEC: The Grand Canyon's Rate of Erosion  

NSDL National Science Digital Library

Question: Some geologic processes, like volcanism and earthquakes, occur intermittently but can cause significant and sometimes catastrophic change very quickly. Others, like weathering, act continuously but gradually, in fact, imperceptibly slow. Regardless of how they operate, geologic processes, acting over long periods of time (thousands and millions of years) will produce significant change in the earth's surface. If you were to occasionally visit the Grand Canyon over a period of many years, you would most likely notice no change. Even the details in the walls would probably seem frozen forever. Yet the Colorado River is continuously, albeit very slowly, cutting into and eroding the Colorado Plateau. The Grand Canyon is gradually being deepened and enlarged. Some geologists are finding evidence that suggests that this mile deep canyon may have been cut with the last 4 million years. Assuming a uniform rate of erosion and without considering canyon widening due to slop retreat, calculate how much (in millimeters per year) the Colorado River would have to downcut per year to form this mile-deep canyon in 4 million years.

Kresan, Peter

348

Organic geochemistry of submarine canyons: The Portuguese Margin  

NASA Astrophysics Data System (ADS)

The organic geochemistry of the Portuguese Margin of the North-Eastern Atlantic Ocean reveals a highly heterogeneous environment that is strongly influenced by canyons that incise the continental margin. Suspended particulate organic matter (sPOM) is funnelled through the canyons to the deep sea, particularly in the Nazaré Canyon where there are high concentrations of sPOM even at >2000 m water depth. The nature of the sPOM through the water column varies, with that transported through the canyons having higher contributions of terrestrial organic matter (higher C/N and larger contribution of land plant-derived lipids) than sPOM in overlying waters and close to the seafloor on the adjacent slope. Zooplankton-derived lipids dominate sPOM associated with the upper and lower boundaries of the Mediterranean Overflow Water (MOW˜600 and 1500 m, respectively). Canyon sediments are enriched in organic carbon when compared to slope sediments, but sedimentary organic matter also appears to derive from multiple sources and undergoes significant alteration prior to deposition. On the open slope, low sedimentation rates and long oxygen exposure times lead to intensive oxidation of organic matter.

Kiriakoulakis, Kostas; Blackbird, Sabena; Ingels, Jeroen; Vanreusel, Ann; Wolff, George A.

2011-12-01

349

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

350

Sandwave migration in Monterey Submarine Canyon, Central California  

USGS Publications Warehouse

Repeated high-resolution multibeam bathymetric surveys from 2002 through 2006 at the head of the Monterey Submarine Canyon reveal a sandwave field along the canyon axis between 20 and 250??m water depth. These sandwaves range in wavelength from 20 to 70??m and 1 to 3??m in height. A quantitative measure was devised to determine the direction of sandwave migration based on the asymmetry of their profiles. Despite appreciable spatial variation the sandwaves were found to migrate in a predominantly down-canyon direction, regardless of season and tidal phases. A yearlong ADCP measurement at 250??m water depth showed that intermittent internal tidal oscillations dominated the high-speed canyon currents (50-80??cm/s), which are not correlated with the spring-neap tidal cycle. Observed currents of 50??cm/s or higher were predominantly down-canyon. Applying a simple empirical model, flows of such magnitudes were shown to be able to generate sandwaves of a size similar to the observed ones. ?? 2007 Elsevier B.V. All rights reserved.

Xu, J.P.; Wong, F.L.; Kvitek, R.; Smith, D.P.; Paull, C.K.

2008-01-01

351

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

...Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California. 165.1155 Section 165.1155 Navigation and Navigable...Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California. (a) Location. The following area is a security...

2014-07-01

352

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. 165.1155 Section 165.1155 Navigation and Navigable...Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California. (a) Location. The following area is a security...

2013-07-01

353

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. 165.1155 Section 165.1155 Navigation and Navigable...Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California. (a) Location. The following area is a security...

2012-07-01

354

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. 165.1155 Section 165.1155 Navigation and Navigable...Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California. (a) Location. The following area is a security...

2011-07-01

355

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. 165.1155 Section 165.1155 Navigation and Navigable...Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California. (a) Location. The following area is a security...

2010-07-01

356

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

Federal Register 2010, 2011, 2012, 2013

...for the Backcountry Management Plan, Grand Canyon...for the Backcountry Management Plan for Grand Canyon...protecting natural and cultural resources while providing...research activities, management of natural and cultural resources, and...

2011-04-27

357

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

358

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

359

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

Federal Register 2010, 2011, 2012, 2013

...Renewal, Glen Canyon Dam Adaptive Management Work Group AGENCY: Bureau of Reclamation, Interior...for the Glen Canyon Dam Adaptive Management Work Group. The purpose of the Adaptive Management Work Group is to provide advice and...

2013-09-04

360

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

Federal Register 2010, 2011, 2012, 2013

...Renewal, Glen Canyon Dam Adaptive Management Work Group AGENCY: Bureau of Reclamation, Interior...for the Glen Canyon Dam Adaptive Management Work Group. The purpose of the Adaptive Management Work Group is to advise and to provide...

2011-09-01

361

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

Federal Register 2010, 2011, 2012, 2013

...Reclamation Glen Canyon Dam Adaptive Management Work Group (AMWG) AGENCY: Bureau of Reclamation...Federal advisory committee, the Adaptive Management Work Group (AMWG), a Technical Work Group (TWG), a Grand Canyon Monitoring and...

2010-01-05

362

76 FR 584 - Glen Canyon Dam Adaptive Management Program Work Group (AMWG)  

Federal Register 2010, 2011, 2012, 2013

...Reclamation Glen Canyon Dam Adaptive Management Program Work Group (AMWG) AGENCY: Bureau of Reclamation...Federal advisory committee, the Adaptive Management Work Group (AMWG), a technical work group (TWG), a Grand Canyon Monitoring and...

2011-01-05

363

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

Microsoft Academic Search

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

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

2006-01-01

364

Deep-marine tidal bottom currents and their reworked sands in modern and ancient submarine canyons  

Microsoft Academic Search

Submarine canyons provide a unique setting for tidal processes to operate from shallow-marine to deep-marine environments. In modern canyons, current-meter measurements at varying water depths (46–4200 m) show a close correlation between the timing of up- and down-canyon currents and the timing of semi-diurnal tides. These tidal bottom currents in submarine canyons commonly attain maximum velocities of 25–50 cm\\/s. Based

G. Shanmugam

2003-01-01

365

Human Jamestown canyon virus infection --- Montana, 2009.  

PubMed

Jamestown Canyon virus (JCV) is a mosquito-borne zoonotic pathogen belonging to the California serogroup of bunyaviruses. Although JCV is widely distributed throughout temperate North America, reports of human JCV infection in the United States are rare. This is the first report of human JCV infection detected in Montana, one of only 15 cases reported in the United States since 2004, when JCV became reportable. On May 26, 2009, a man aged 51 years with no travel history outside of Montana went to a local emergency department immediately following onset of fever, severe frontal headache, dizziness, left-sided numbness, and tingling. His blood pressure was elevated. Stroke was ruled out, oxygen was administered, medication was prescribed for hypertension, and the patient was sent home. One week later, the patient visited his primary-care physician complaining of continued neurologic symptoms consistent with acute febrile encephalitis and recent mosquito bites. Although West Nile virus (WNV) disease was diagnosed based on detection of WNV-immunoglobulin M (IgM) and G (IgG) antibodies, subsequent testing indicated that the WNV antibodies were from a past infection and that his illness was caused by JCV. The final diagnosis of JCV infection was based on positive JCV-specific IgM enzyme-linked immunosorbent assay (ELISA) results and a fourfold rise in paired sample JCV plaque reduction neutralization test (PRNT) titers. This finding represents a previously unrecognized risk for JCV infection in Montana; clinicians should consider JCV infection when assessing patients for suspected arboviral infections. PMID:21617630

2011-05-27

366

Numerical modeling of tectonic and aeolian processes on Mars  

Microsoft Academic Search

This dissertation reports on two numerical studies for the surface evolution of Mars. The first study focuses on three models for the tectonic formation of the Valles Marineris. The second study models the disposition, transport pathways, and history of sand on Mars. Three types of terrestrial rift models were formulated for the lithospheric conditions of the Valles Marineris to understand

Fletcher Scott Anderson

1998-01-01

367

Z .Geomorphology 37 2001 329352 www.elsevier.nlrlocatergeomorph  

E-print Network

and tectonics of Valles Marineris z /wallslopes Mars Jean-Pierre Peulvast a,) , Daniel Mege b , Jan Chiciak c the walls of the Valles Marineris troughs. The widest and deepest troughs are grabens, in which tectonics and profiles show that they result from complex, persistent tectonic influences, and that significant changes

Mege, Daniel

368

Origin of Izu-Bonin forearc submarine canyons  

SciTech Connect

Submarine canyons on the Izu-Bonin forearc are morphologically divided from north to south into four types based on their morphology, long profiles, and seismic profiles: Mikura, Aogashima, Sofu, and Chichijima types, respectively. These types of canyons are genetically different from each other. Mikura group is formed by the faults related to bending of the subducting Philippine Sea Plate. Aogashima type genetically relates to the activity of large submarine calderas that supply large amounts of volcaniclastic material to the consequent forearc slope. The third, Sofu group, is thought to be formed by the large-scale mega mass wasting in relation to the recent movement of the Sofugan tectonic line. The last, Chichijima group, is formed by collision of the Uyeda Ridge and the Ogasawara Plateau on the subducting Pacific Plate with Bonin Arc. Long profiles of four types of submarine canyons also support this.

Fujioka, Kantaro (Univ. of Tokyo (Japan)); Yoshida, Haruko (Chiba Univ. (Japan))

1990-06-01

369

Grand Canyon, Arizona as seen from STS-66  

NASA Technical Reports Server (NTRS)

Snow covers the Kaibab Plateau on the northern side of the Colorado River in this November, 1994 view of the Grand Canyon. North is to the bottom of this view. The Colorado River has created a canyon which cuts through billions of years of geologic time. The Grand Canyon is 446 kilometers (277 miles) long, averages 16 kilometers (10 miles) wide, and is approximately 1.6 kilometers (1 mile) deep. The Coconino Plateau is located on the upper left side of the view, or to the south of the Colorado River. The direction of the flow of the Colorado River is from the east to the west. Eventually the river turns south and empties into the Gulf of California. The southern portion of Lake Powell in Utah can be seen at the bottom center of the view.

1994-01-01

370

Canyon sand -- S. W. Texas example of a low permeability gas reservoir  

Microsoft Academic Search

Canyon sands are Upper Pennsylvanian deposits found in the Val Verde basin and on the Permian Basin eastern shelf, Texas, and occur in a thick clastic sequence overlying the Strawn limestone. These sandstones are considered to have been deposited during Missourian time and are formally named after the Canyon group deposited on the eastern shelf. The Canyon sand has provided

Trabelsi

1994-01-01

371

Sedimentary features and processes in the Nazaré and Setúbal submarine canyons, west Iberian margin  

Microsoft Academic Search

Here we present part of the first complete sidescan sonar dataset of the Nazaré and Setúbal Canyons, west Iberian margin, which, in combination with multibeam bathymetry, shallow seismic profiles and precise piston coring of intra-canyon targets, are used to characterise the sedimentary dynamics of these deep-sea settings. The results show that Nazaré and Setúbal Canyons are highly complex environments. They

Raquel G. Arzola; Russell B. Wynn; Galderic Lastras; Douglas G. Masson; Philip P. E. Weaver

2008-01-01

372

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

373

A wind tunnel study of organised and turbulent air motions in urban street canyons  

Microsoft Academic Search

High concentrations of car-exhaust gases in urban street canyons are typically associated with low wind velocities or situations when the wind blows perpendicular to the canyon axis. The latter flow configuration has been studied in a wind tunnel model of a street canyon. The mean flow and turbulence structure have both been investigated and comparisons have been carried out with

P. Kastner-Klein; E. Fedorovich; M. W. Rotach

2001-01-01

374

Concentration and flow distributions in urban street canyons: wind tunnel and computational data  

Microsoft Academic Search

The goal of this paper is to present bluff body flow and transport from steady point sources of pollutants, or chemical and biological agents in an idealized urban environment This paper includes ventilation behavior in different street canyon configurations. To evaluate dispersion in a model urban street canyon, a series of tests with various street canyon aspect ratios (B\\/H) are

Cheng-Hsin Chang; Robert N. Meroney

2003-01-01

375

76 FR 14802 - Modification of Class E Airspace; Bryce Canyon, UT  

Federal Register 2010, 2011, 2012, 2013

...at Bryce Canyon Airport. DATES: Effective...with the possible impact of noise on the Bryce Canyon...existing patterns of noise generation. With...at Bryce Canyon Airport. This action...of a regulatory evaluation as the anticipated impact is so...

2011-03-18

376

Bioavailable organic matter in surface sediments of the Nazaré canyon and adjacent slope (Western Iberian Margin)  

NASA Astrophysics Data System (ADS)

The distribution of bioavailable organic matter in surface sediments of the Nazaré submarine canyon and adjacent open slope was investigated. The concentration of chlorophyll a (chl a), phaeopigments (phaeo), chloroplastic pigment equivalents (CPE) and total hydrolyzable amino acids (THAA) decreased with increasing water depth, and were in general higher within the canyon (specially in the upper regions) than on the open slope. The concentrations were low on the canyon walls, increasing towards the canyon axis. The chl a:phaeo ratio, degradation index (DI), asp:?-ala and glu:?-aba ratios were highest in the upper canyon, and similarly low in the deeper canyon and along the open slope. On the canyon axis and walls these lability indices were similar. chl a:OM ratio indicated that the quality of the bulk organic matter in the upper canyon was higher than on the slope and deeper canyon regions. Bioavailable organic matter enters the canyon through the upper region; it is transported down canyon by the tide circulation, where it is dispersed across a bigger area under a more refractory state. Flume experiments demonstrate that arborescent foraminifera and polychaete pellet mounds, as found in the head of the canyon; increase deposition of phytodetritus under critical shear velocities by a 50%.

García, R.; Thomsen, L.

2008-11-01

377

Morphotectonics and incision of the Kaoping submarine canyon, SW Taiwan orogenic wedge  

E-print Network

Morphotectonics and incision of the Kaoping submarine canyon, SW Taiwan orogenic wedge Cheng February 2006 Available online 24 March 2006 Abstract The Kaoping submarine canyon developed on the frontal; Incision; Submarine canyon; Taiwan 1. Introduction 1.1. Geological settings The island of Taiwan is located

Lin, Andrew Tien-Shun

378

Weighting models for GPS Pseudorange observations for land transportation in urban canyons  

E-print Network

Weighting models for GPS Pseudorange observations for land transportation in urban canyons Sarab variances modelling, in order to solve for vehicle position in an urban canyon. Keywords--GNSS signal propagation, urban canyons, multi- path, state of reception, weighting models, carrier-to-noise ratio

Paris-Sud XI, Université de

379

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

E-print Network

625 Habitat associations of deep-water rockfishes in a submarine canyon: an example of a natural (genus Se- bastes) and associated habitats in deep water was conducted in Soquel Sub- marine Canyon of high relief interspersed with mud in deep water of narrow submarine canyons are less accessible

380

Thermochronometer and Numerical Modeling Constraints on Canyon Incision and Topographic Evolution, SW Peru (Invited)  

Microsoft Academic Search

Deeply incised canyons demonstrate the net effects of physical processes active at Earth's surface in response to surface uplift. Low-temperature thermochronometry can constrain rates of bedrock incision, which are necessary for relating canyon incision to surface uplift over geological timescales. Combined with studies of the incision process and potential delays between uplift and river incision, deep canyons can preserve one

T. F. Schildgen; G. Balco; D. L. Shuster; T. A. Ehlers; K. Hodges; K. X. Whipple

2009-01-01

381

A multidisciplinary study of the role of submarine canyons off western Portugal  

Microsoft Academic Search

A multidisciplinary research aimed to characterise the dominant aspects of the Portuguese canyon systems and their role on the shelf-deep ocean sediment exchanges is being conducted in the framework of EU project Eurostrataform. Three contrasting systems are studied: (1) the Nazaré Canyon is a narrow and deep canyon which extends from the deep ocean and completely cuts the NW Portuguese

J. Vitorino; A. Oliveira; A. Rodrigues

2003-01-01

382

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

383

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

384

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

USGS Publications Warehouse

The development and application of acoustic and optical technologies and of accurate positioning systems in the past 30 years have opened new frontiers in the submarine canyon research communities. This paper reviews several key advancements in both technology and science in the field of currents in submarine canyons since the1979 publication of Currents in Submarine Canyons and Other Sea Valleys by Francis Shepard and colleagues. Precise placements of high-resolution, high-frequency instruments have not only allowed researchers to collect new data that are essential for advancing and generalizing theories governing the canyon currents, but have also revealed new natural phenomena that challenge the understandings of the theorists and experimenters in their predictions of submarine canyon flow fields. Baroclinic motions at tidal frequencies, found to be intensified both up canyon and toward the canyon floor, dominate the flow field and control the sediment transport processes in submarine canyons. Turbidity currents are found to frequently occur in active submarine canyons such as Monterey Canyon. These turbidity currents have maximum speeds of nearly 200 cm/s, much smaller than the speeds of turbidity currents in geological time, but still very destructive. In addition to traditional Eulerian measurements, Lagrangian flow data are essential in quantifying water and sediment transport in submarine canyons. A concerted experiment with multiple monitoring stations along the canyon axis and on nearby shelves is required to characterize the storm-trigger mechanism for turbidity currents. ?? 2011 Geological Society of America.

Xu, J.P.

2011-01-01

385

Macrofaunal communities within and adjacent to a detritus-rich submarine canyon system  

Microsoft Academic Search

Macrofaunal abundance, biomass, diversity and species assemblages within Scripps and La Jolla Submarine Canyons are compared with those on the nearby continental shelf and slope. Our primary objective was to examine the effect of detrital aggregates on infaunal communities within canyons. Two submarines, a remotely operated vehicle (ROV), and a Soutar box-corer were used to collect samples. Within the canyons,

E. W. Vetter; P. K. Dayton

1998-01-01

386

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

387

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

388

Hydrological Sulfur Cycling in the Volcanic Complex of Valles Caldera, New Mexico — Geochemical Implications for Mars  

NASA Astrophysics Data System (ADS)

To address the role of volcanic S on Mars, we have been studying the modern and past hydrological S cycle related to volcanic S emission and aqueous chemical weathering of the large terrestrial volcanic system of Valles Caldera, New Mexico.

Szynkiewicz, A.; Vaniman, D. T.; Goff, F.; Subia, T.; Sanchez, D.; Faiia, A. M.; Coleman, J.

2014-07-01

389

Geomorphology and sedimentary features in the Central Portuguese submarine canyons, Western Iberian margin  

NASA Astrophysics Data System (ADS)

The Central Portuguese submarine canyons (Nazaré, Cascais and Setúbal-Lisbon canyons) dissect the Western Iberian margin in an east-west direction from the continental shelf, at water depths shallower than 50 m, down to the Tagus and Iberian abyssal plains, at water depths exceeding 5000 m. We present an analysis of the geomorphology of the canyons and of the sedimentary processes that can be inferred from the observed morphology of the three canyons, based on a compilation of swath bathymetry data and TOBI deep-towed side-scan sonar imagery. This first complete detailed mapping of the Central Portuguese canyons reveals substantial differences in their morphologies and downslope evolution. The canyons are divided into three sections: 1) canyon head and upper reach, 2) middle canyon, and 3) canyon mouth and distal part. The canyon heads and upper reaches are severely indented into the continental shelf, and they are characterised, in the Nazaré and Setúbal-Lisbon canyons, by sinuous V-shaped valleys entrenched within high canyon walls occupied by rock outcrops dissected by gullies. The Cascais upper canyon is complex, with multiple branches with high axial gradients and signs of mass wasting. Middle canyon sections, indented in the slope, display axial incisions with perched, stacked terraces, and are affected by debris avalanches originating from the canyon walls. At the base of slope, the distal Cascais and Setúbal-Lisbon canyons show many characteristics of channel-lobe transition zones: erosional features such as isolated to amalgamated chevron scours, and depositional bedforms such as mud to gravel waves. Pervasive scouring occurs up to 95 km beyond the canyon mouths. By contrast, the Nazaré canyon opens into a 27 km wide and 94 km long channel, whose flat-bottomed thalweg is occupied by sediment waves, irregular, comet-shaped and crescentic scours, and a second-order channel. Transverse, kilometre-scale sediment waves occupy the overbank area of the southern channel margin. The present morphology of the Central Portuguese canyons is the result of erosive processes, subsequent sediment transport and deposition, and sediment instability, whereas inherited tectonic fabric controls their location. Morphological differences between the canyons are explained by the main mechanisms driving their activity. Overall, these morphological features suggest that these canyons have acted as an efficient conduit of sediment to the deep basin, transporting large quantities of material to the deep sea during high-energy events.

Lastras, G.; Arzola, R. G.; Masson, D. G.; Wynn, R. B.; Huvenne, V. A. I.; Hühnerbach, V.; Canals, M.

2009-02-01

390

Happy Canyon - A new type of enstatite achondrite  

NASA Technical Reports Server (NTRS)

Mineralogical and chemical characteristics of the Happy Canyon meteorite, found in 1971 near Wayside, Texas, show it to be a new type of enstatite achondrite occupying the gap between the recrystallized enstatite chondrites and the igneous, crystalline, unbrecciated enstatite chondrites. Although the bulk composition of the specimen is consistent with that of an E6 enstatite chondrite, it has a crystal cumulate texture. There are minor amounts of metal and troilite which have survived extensive weathering. The Happy Canyon meteorite may represent an E6 composition which has melted and reprecipitated at a slightly higher oxidation state, possibly in the core of a small parent body.

Olsen, E. J.; Bunch, T. E.; Jarosewich, E.; Noonan, A. F.; Huss, G. I.

1977-01-01

391

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

392

Early Agriculture in the Eastern Grand Canyon of Arizona, USA  

USGS Publications Warehouse

Abandoned fields in Colorado River alluvium in the eastern Grand Canyon show signs of primitive agriculture. Presence of maize pollen in association with buried soils near Comanche Creek suggests that farming began prior to 3130 yr B.P. Cotton pollen, identified in buried soils near Nankoweap Creek, dates to 1310 yr B.P., approximately 500 years earlier than previously reported anywhere on the Colorado Plateau. Farming spanned three millennia in this reach of the canyon. Entrenchment, starting approximately 700 yr B.P., making water diversion to fields infeasible, was likely responsible for field abandonment. ?? 2000 John Wiley & Sons, Inc.

Davis, S.W.; Davis, M.E.; Lucchitta, I.; Finkel, R.; Caffee, M.

2000-01-01

393

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

394

MEVTV Workshop on Tectonic Features on Mars  

NASA Astrophysics Data System (ADS)

The state of knowledge of tectonic features on Mars was determined and kinematic and mechanical models were assessed for their origin. Three sessions were held: wrinkle ridges and compressional structure; strike-slip faults; and extensional structures. Each session began with an overview of the features under discussion. In the case of wrinkle ridges and extensional structures, the overview was followed by keynote addresses by specialists working on similar structures on the Earth. The first session of the workshop focused on the controversy over the relative importance of folding, faulting, and intrusive volcanism in the origin of wrinkle ridges. The session ended with discussions of the origin of compressional flank structures associated with Martian volcanoes and the relationship between the volcanic complexes and the inferred regional stress field. The second day of the workshop began with the presentation and discussion of evidence for strike-slip faults on Mars at various scales. In the last session, the discussion of extensional structures ranged from the origin of grabens, tension cracks, and pit-crater chains to the origin of Valles Marineris canyons. Shear and tensile modes of brittle failure in the formation of extensional features and the role of these failure modes in the formation of pit-crater chains and the canyons of Valles Marineris were debated. The relationship of extensional features to other surface processes, such as carbonate dissolution (karst) were also discussed.

Watters, Thomas R.; Golombek, Matthew P.

395

MEVTV Workshop on Tectonic Features on Mars  

NASA Technical Reports Server (NTRS)

The state of knowledge of tectonic features on Mars was determined and kinematic and mechanical models were assessed for their origin. Three sessions were held: wrinkle ridges and compressional structure; strike-slip faults; and extensional structures. Each session began with an overview of the features under discussion. In the case of wrinkle ridges and extensional structures, the overview was followed by keynote addresses by specialists working on similar structures on the Earth. The first session of the workshop focused on the controversy over the relative importance of folding, faulting, and intrusive volcanism in the origin of wrinkle ridges. The session ended with discussions of the origin of compressional flank structures associated with Martian volcanoes and the relationship between the volcanic complexes and the inferred regional stress field. The second day of the workshop began with the presentation and discussion of evidence for strike-slip faults on Mars at various scales. In the last session, the discussion of extensional structures ranged from the origin of grabens, tension cracks, and pit-crater chains to the origin of Valles Marineris canyons. Shear and tensile modes of brittle failure in the formation of extensional features and the role of these failure modes in the formation of pit-crater chains and the canyons of Valles Marineris were debated. The relationship of extensional features to other surface processes, such as carbonate dissolution (karst) were also discussed.

Watters, Thomas R. (editor); Golombek, Matthew P. (editor)

1989-01-01

396

MEVTV workshop on tectonic features on Mars  

SciTech Connect

The state of knowledge of tectonic features on Mars was determined and kinematic and mechanical models were assessed for their origin. Three sessions were held: wrinkle ridges and compressional structure; strike-slip faults; and extensional structures. Each session began with an overview of the features under discussion. In the case of wrinkle ridges and extensional structures, the overview was followed by keynote addresses by specialists working on similar structures on the Earth. The first session of the workshop focused on the controversy over the relative importance of folding, faulting, and intrusive volcanism in the origin of wrinkle ridges. The session ended with discussions of the origin of compressional flank structures associated with Martian volcanoes and the relationship between the volcanic complexes and the inferred regional stress field. The second day of the workshop began with the presentation and discussion of evidence for strike-slip faults on Mars at various scales. In the last session, the discussion of extensional structures ranged from the origin of grabens, tension cracks, and pit-crater chains to the origin of Valles Marineris canyons. Shear and tensile modes of brittle failure in the formation of extensional features and the role of these failure modes in the formation of pit-crater chains and the canyons of Valles Marineris were debated. The relationship of extensional features to other surface processes, such as carbonate dissolution (karst) were also discussed.

Watters, T.R.; Golombek, M.P.

1989-01-01

397

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

398

On the Quantitative Impact of the Schechter-Valle Theorem  

E-print Network

We evaluate the Schechter-Valle (Black Box) theorem quantitatively by considering the most general Lorentz invariant Lagrangian consisting of point-like operators for neutrinoless double beta decay. It is well known that the Black Box operators induce Majorana neutrino masses at four-loop level. This warrants the statement that an observation of neutrinoless double beta decay guarantees the Majorana nature of neutrinos. We calculate these radiatively generated masses and find that they are many orders of magnitude smaller than the observed neutrino masses and splittings. Thus, some lepton number violating New Physics (which may at tree-level not be related to neutrino masses) may induce Black Box operators which can explain an observed rate of neutrinoless double beta decay. Although these operators guarantee finite Majorana neutrino masses, the smallness of the Black Box contributions implies that other neutrino mass terms (Dirac or Majorana) must exist. If neutrino masses have a significant Majorana contribution then this will become the dominant part of the Black Box operator. However, neutrinos might also be predominantly Dirac particles, while other lepton number violating New Physics dominates neutrinoless double beta decay. Translating an observed rate of neutrinoless double beta decay into neutrino masses would then be completely misleading. Although the principal statement of the Schechter-Valle theorem remains valid, we conclude that the Black Box diagram itself generates radiatively only mass terms which are many orders of magnitude too small to explain neutrino masses. Therefore, other operators must give the leading contributions to neutrino masses, which could be of Dirac or Majorana nature.

Michael Duerr; Manfred Lindner; Alexander Merle

2011-05-04

399

Stratigraphic and structural controls on fluorspar mineralization in northern Valle Las Norias, Coahuila, Mexico  

E-print Network

STRATIGRAPHIC AND STRUCTURAL CONTROLS ON FLUORSPAR MINERALIZATION IN NORTHERN VALLE LAS NORIAS, COAHUILA, MEXICO A Thesis by ERIC JOHN RAPPORT Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE December 1983 Major Subject: Geology STRATIGRAPHIC AND STRUCTURAL CONTROLS ON FLUORSPAR MINERALIZATION IN NORTHERN VALLE LAS NORIAS, COAHUILA, MEXICO A Thesis by ERIC JOHN RAPPORT Approved as to style and content by...

Rapport, Eric John

1983-01-01

400

Elaphopsocoides, a new genus of Psocidae (Psocodea: ´Psocoptera´) from Valle del Cauca, Colombia.  

PubMed

Two new species of Elaphopsocoides n. gen. from Valle del Cauca, Colombia, are here described and illustrated. The new genus is related to Elaphopsocus Roesler, but differs from it mostly in the hypandrial projections and in phallosome structure. The female subgenital plate has a distinct, median, posterior projection. The types are deposited in the Entomology Museum, Universidad del Valle (MUSENUV), Santiago de Cali, Colombia. PMID:25544209

Román-P, Cristian; Aldrete, Alfonso N García; Obando, Ranulfo González

2014-01-01

401

Multi-stage uplift of the Colorado Plateau and the age of Grand Canyon and precursor canyons  

NASA Astrophysics Data System (ADS)

Debates about the age of Grand Canyon link to debates about the timing of surface uplift(s) of the Colorado Plateau- Rocky Mountain (CP-RM) region. One "old Grand Canyon" model proposes that a paleocanyon of almost the same depth and location as today's Grand Canyon was carved by a NE-flowing "California" paleoriver 80-70 Ma, then was re-used at ~55 Ma by a SW-flowing "Arizona" paleoriver. This model postulates the CP-RM region was uplifted to near modern elevations during the Laramide orogeny. A second model postulates a 17 Ma Grand Canyon; this time corresponds to Basin and Range extension and postulated mantle-driven surface uplift. The "young Grand Canyon" model postulates that >2/3 of modern Grand Canyon was carved by W-flowing Colorado River that became integrated to the Gulf of California at 5-6 Ma during Neogene mantle-driven uplift of the CP/RM region. Thermochronologic data are poised to substantially resolve these debates. Our thermochronology dataset combines published and new apatite fission-track and helium analyses, and joint thermal history modeling using both systems. This dataset reveals three major cooling episodes: 1) a multi-stage Sevier-Laramide contraction episode from about 90 Ma to 50 Ma with structural relief on upwarps on the order 0.5-1 km, compatible with a similar magnitude of surface uplift; 2) 30-20 Ma cooling that was associated with denudation and northward cliff retreat of most of the Mesozoic section from Grand Canyon region; 3) <10 Ma cooling that is best documented in eastern Grand Canyon as part of a general pattern of decreasing age of cooling/denudation to the NE. Combined geologic and thermochronologic data define the age and 3-D geometry of Cenozoic paleotopography that led to Grand Canyon carving. Combined AHe and AFT data indicate 2-4 km of sedimentary rocks covered the Grand Canyon region until about 40 Ma, negating the California River model. These strata were not removed from the Marble Canyon area until after about 25 Ma, negating the Arizona River hypothesis. However, significant paleorelief and paleovalleys were present and their geometry is coming into focus. 1) A long-recognized N-flowing "Peach Springs paleocanyon" existed from Eocene to about 17 Ma and potentially helped carve a paleocanyon along the Hurricane fault, from Truxton to river mile (RM) 225-190. Drill data and modern topography suggest that the NE slope of this paleodrainage has been inverted to a modern SW slope by surface tilting of the CP. 2) An "East Kaibab" paleocanyon was carved across the southern Kaibab uplift to below the Kaibab surface during 30-20 Ma exhumation. This Miocene paleocanyon extended from RM 65 to 116 in the present position of Upper Granite Gorge and may have flowed west (Crooked Ridge River) or east (as an outlet for the 18 Ma Peach Springs paleocanyon). These data support a model of multiple exhumation episodes leading to a 5-6 Ma Grand Canyon that was mainly carved by the W-flowing Colorado River, but that re-used and deepened older paleovalley segments

Karlstrom, K. E.; Lee, J. P.; Kelley, S. A.; Crow, R.

2012-12-01

402

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

USGS Publications Warehouse

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

Normark, William R.; Carlson, Paul R.

2003-01-01

403

Submarine canyons as important habitat for cetaceans, with special reference to the Gully: A review  

NASA Astrophysics Data System (ADS)

There has been much research interest in the use of submarine canyons by cetaceans, particularly beaked whales (family Ziphiidae), which appear to be especially attracted to canyon habitats in some areas. However, not all submarine canyons are associated with large numbers of cetaceans and the mechanisms through which submarine canyons may attract cetaceans are not clearly understood. This paper reviews some of the cetacean associations with submarine canyons that have been anecdotally described or presented in scientific literature and discusses the physical, oceanographic and biological mechanisms that may lead to enhanced cetacean abundance around these canyons. Particular attention is paid to the Gully, a large submarine canyon and Marine Protected Area off eastern Canada for which there exists some of the strongest evidence available for submarine canyons as important cetacean habitat. Studies demonstrating increased cetacean abundance in the Gully and the processes that are likely to attract cetaceans to this relatively well-studied canyon are discussed. This review provides some limited evidence that cetaceans are more likely to associate with larger canyons; however, further studies are needed to fully understand the relationship between the physical characteristics of canyons and enhanced cetacean abundance. In general, toothed whales (especially beaked whales and sperm whales) appear to exhibit the strongest associations with submarine canyons, occurring in these features throughout the year and likely attracted by concentrating and aggregating processes. By contrast, baleen whales tend to occur in canyons seasonally and are most likely attracted to canyons by enrichment and concentrating processes. Existing evidence thus suggests that at least some submarine canyons are important foraging areas for cetaceans, and should be given special consideration for cetacean conservation and protection.

Moors-Murphy, Hilary B.

2014-06-01

404

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

405

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

406

PUBLISHED ONLINE: 20 JUNE 2010 | DOI: 10.1038/NGEO894 Rapid formation of a modern bedrock canyon by a  

E-print Network

canyon by a single flood event Michael P. Lamb1 * and Mark A. Fonstad2 Deep river canyons are thought few years2,3 . In contrast, some of the most spectacular canyons on Earth and Mars were probably and erosion mechanics that operated during such events is hampered because we lack modern analogues. Canyon

407

Submarine canyon and slope processes of the U.S. Atlantic continental margin  

USGS Publications Warehouse

Two regions on the U.S. Atlantic continental margin were surveyed using single-channel, seismic-reflection profiling techniques: the Mid-Atlantic Continental Slope and Rise seaward of New Jersey in the vicinity of Baltimore Canyon and the Continental Slope and upper Rise just north of Cape Hatteras. Submarine canyons are the dominant morphologic feature in both areas. The Continental Slope in the Baltimore Canyon area has a general sea-floor gradient of 3?-4? and a width of approximately 40 km, whereas the study area north of Cape Hatteras has a general sea-floor gradient of approximately 9? and a width of 20 km. The dominant slope process differs in each area. In the Baltimore Canyon area, subbottom reflectors suggest that sediment deposition with progradation of the slope is related to canyon processes. In the study area north of Cape Hatteras, the canyons appear erosional and mass wasting is the dominant erosional process. Dominant slope processes appear to be correlated with the width and sea-floor gradient of the Continental Slope. Although the absolute age of the canyons is difficult to determine without rotary-drill cores for stratigraphic control, Baltimore Canyon is suggested to be older than the shelf-indenting canyon just north of Cape Hatteras. An anomalously large ridge flanking Baltimore Canyon on the upper rise appears to be related to canyon depositional and erosional processes.

McGregor, B.A.

1983-01-01

408

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

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

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

409

College of the Canyons Syllabus Survey, Spring 2002. Report.  

ERIC Educational Resources Information Center

This study was conducted at College of the Canyons (COC), California, in spring 2002 by the Office of Institutional Development and Technology, along with Communications Studies instructor Victoria Leonard. Eighty-three class sections were surveyed to determine the degree to which students agreed or disagreed that their course syllabus clearly…

Meuschke, Daylene M.; Gribbons, Barry C.; Dixon, Scott P.

410

Geology Fieldnotes: Bighorn Canyon National Recreation Area, Montana/Wyoming  

NSDL National Science Digital Library

This site contains Bighorn Canyon National Recreation Area information, including geology, maps, photographs, visitor information, and links for additional facts about this area of Wyoming and Montana. Included are details about the geologic history of the area, formations, the Pryar and Bighorn Mountains, and the exploration history of the land.

411

Geology of the Big Brushy canyon area, Brewster County, Texas  

E-print Network

is conformable in thc Varavilbas Canyon quadrangle, Xn that axoa the sequence is gradatiennl from thin beds of' sof't earls and nodulax limestones into nodulax limestonss of' tbe lower Buda, The uppex limestone unit of' ths Buda is not f'ound in eontaot...

Howle, Arlen Guy

2012-06-07

412

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

413

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

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

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

414

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

415

Litter in submarine canyons off the west coast of Portugal  

Microsoft Academic Search

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

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

2011-01-01

416

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...

417

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...

418

Arctic ocean-shelf exchange: Measurements in Barrow Canyon  

Microsoft Academic Search

Two closely instrumented arrays were deployed within Barrow Canyon during 1986-1987 in an attempt to measure the outflow of dense, hypersaline plumes created during sea ice formation along the Alaskan coast. However, no hypersaline plumes were observed. Rather, we found cold, relatively fresh waters advected downcanyon by the mean flow alternating with upcanyon flow of warm and saline water upwelled

K. Aagaard; A. T. Roach

1990-01-01

419

HELL'S CANYON STUDY, IDAHO AND NEZ PERCE COUNTIES, IDAHO, 1977  

EPA Science Inventory

In September of 1975 and again in March and June of 1976, water quality survey runs were made in Hells Canyon (17060103, 17060101) to obtain information on the Snake River and its major tributaries within the area. The surveys included 5 Snake River stations from above Johnson B...

420

Effects of off-road vehicles in Ballinger Canyon, California  

Microsoft Academic Search

Recreational use of vehicles, mainly motorcycles, off constructed roads and trails has been heavy in Ballinger Canyon, Los Padres National Forest, California, for the past 8 yr. The vegetation and shallow soils of this arid area have proved sensitive to such use. In the heaviest-use zones, soil and bedrock losses from individual vehicle trails average 600 kg · m-2. Erosion

Robert Stull; Susan Shipley; Eric Hovanitz; Scott Thompson; Karen Hovanitz

1979-01-01

421

Geology Fieldnotes: Sequoia and Kings Canyon National Parks, California  

NSDL National Science Digital Library

Ranging from 1500' to 14,494' in elevation, these adjoining California parks protect immense mountains, deep canyons, huge trees, and stunningly diverse habitats. The site briefly discusses Moro Rock and the process of exfoliation, which causes such dome-like forms, and includes links to visitor information and additional resources.

422

Grand Canyon, Colorado as seen from STS-62  

NASA Technical Reports Server (NTRS)

In this view, the Colorado River can be seen flowing southwest from top left to bottom center-right. The dark wider sections of the river are the water surface of Lake Powell (center, and top left), 110 miles long in a straight line. Grand Canyon National Monument lies lower right, centered on the Grand Canyon of the Colorado River, a 10 mile-wide gash carved more than 5,000 feet deep by the Colorado. The Canyon has cut into the Kaibab Plateau, an uplifted area visible here as a forested area with snow on the highest northern parts. The surrounding parts of the Colorado Plateau are sparsely occupied by brush vegetation and appear yellow-brown. The dark area top right is the wooded country of Black Mesa in Navajoland, divided from Lake Powell by the San Juan River. Four Corners is just outside the pictures (top) where the states of Arizona, Utah, Colorado and New Mexico meet. The Henry Mountains appear top left. Apart from Grand Canyon National Monument, several other famous national mo

1994-01-01

423

Topographic steering of dense currents with application to submarine canyons  

Microsoft Academic Search

The influence of a submarine canyon on a dense bottom current flowing along the continental shelf is considered. It is shown that the front of the current moves forward with the Nof velocity, establishing a stationary plume parallel to the depth contours behind it. The stationary flow has a frictional transport directed downhill, perpendicular to the depth contours. This transport

A. K. Wåhlin

2002-01-01

424

Submarine canyon erosion: contribution of marine rock burrowers.  

PubMed

Rocks of the rim and upper walls of Scripps Submarine Canyon are intensely burrowed by marine invertebrates. Important excavators are bivalves, polychaetes, and sipunculoids whose activities culminate in a network of passageways and eventual disintegration of the rocks. In many localities erosion by animals is more important than erosion by physical and chemical processes. PMID:17836602

Warme, J E; Scanland, T B; Marshall, N F

1971-09-17

425

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

426

Measuring Longwave Radiative Flux Divergence in an Urban Canyon  

NASA Astrophysics Data System (ADS)

There has been very little measurement of longwave radiation divergence since the urban studies of Fuggle, Oke and Nunez in the mid 1970's or the rural work of Funk in the early 1960's. Although radiative divergence has been widely ignored for sometime there is the belief that it may play an important role in balancing nocturnal energy budgets in a range of environments. For example, in urban environments surface temperature relates well to the energy balance whereas air temperature does not, even in non-turbulent conditions. This is probably due at least in part to the effects of longwave divergence. To help answer issues related to longwave divergence a new dual-channel infrared radiometer (DCIR) has been developed. The DCIR, as the name implies, measures the directional infrared radiation in two wavebands and can, through differencing of the signals and further signal processing, give a direct measurement of longwave radiative flux divergence. The DCIR was deployed for the first time as part of a larger study (BUBBLE) of the urban boundary layer of Basel, Switzerland. The objective is to further study the thermal regime of a city at the canyon scale. To this end, a street canyon was carefully selected, in the city of Basel. The canyon surface and air volume were instrumented, including turbulent and conductive fluxes, and standard meteorological variables in addition to radiation. A unique data set was obtained to allow the complete energy balance of the canyon system to be evaluated without the need to resort to using residuals to quantify the magnitude of the longwave radiative flux divergence. Measured values of longwave flux-divergence are converted to cooling rates to compare with measured air temperature cooling. Preliminary results show that at the onset of canyon air-volume cooling, measured cooling rates are slightly lower than radiative cooling rates. The differences are less than 0.5° C. This contrasts sharply with previously measured above roof level and rural differences of greater than 5° C. The difference between the rural and above-canyon case and the in-canyon case is most likely a result of differences in radiative environments and wind and temperature fields. The differences illustrate the strong role of urbanization on the surface energy budget.

Soux, A.; Oke, T. R.; Nunez, M.; Wilson, M.

2003-12-01

427

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

USGS Publications Warehouse

Thermal springs in Black Canyon of the Colorado River, downstream of Hoover Dam, are important recreational, ecological, and scenic features of the Lake Mead National Recreation Area. This report presents the results from a U.S. Geological Survey study of the geologic framework of the springs. The study was conducted in cooperation with the National Park Service and funded by both the National Park Service and National Cooperative Geologic Mapping Program of the U.S. Geological Survey. The report has two parts: A, a 1:48,000-scale geologic map created from existing geologic maps and augmented by new geologic mapping and geochronology; and B, an interpretive report that presents results based on a collection of fault kinematic data near springs within Black Canyon and construction of 1:100,000-scale geologic cross sections that extend across the western Lake Mead region. Exposures in Black Canyon are mostly of Miocene volcanic rocks, underlain by crystalline basement composed of Miocene plutonic rocks or Proterozoic metamorphic rocks. The rocks are variably tilted and highly faulted. Faults strike northwest to northeast and include normal and strike-slip faults. Spring discharge occurs along faults intruded by dacite dikes and plugs; weeping walls and seeps extend away from the faults in highly fractured rock or relatively porous volcanic breccias, or both. Results of kinematic analysis of fault data collected along tributaries to the Colorado River indicate two episodes of deformation, consistent with earlier studies. The earlier episode formed during east-northeast-directed extension, and the later during east-southeast-directed extension. At the northern end of the study area, pre-existing fault blocks that formed during the first episode were rotated counterclockwise along the left-lateral Lake Mead Fault System. The resulting fault pattern forms a complex arrangement that provides both barriers and pathways for groundwater movement within and around Black Canyon. Regional cross sections in this report show that thick Paleozoic carbonate aquifer rocks of east-central Nevada do not extend into the Black Canyon area and generally are terminated to the south at a major tectonic boundary defined by the northeast-striking Lake Mead Fault System and the northwest-striking Las Vegas Valley shear zone. Faults to the west of Black Canyon strike dominantly north-south and form a complicated pattern that may inhibit easterly groundwater movement from Eldorado Valley. To the east of Black Canyon, crystalline Proterozoic rocks locally overlain by Tertiary volcanic rocks in the Black Mountains are bounded by steep north-south normal faults. These faults may also inhibit westerly groundwater movement from Detrital Valley toward Black Canyon. Finally, the cross sections show clearly that Proterozoic basement rocks and (or) Tertiary plutonic rocks are shallow in the Black Canyon area (at the surface to a few hundred meters depth) and are cut by several major faults that discharge most of the springs in the Black Canyon. Therefore, the faults most likely provide groundwater pathways to sufficient depths that the groundwater is heated to the observed temperatures of up to 55 °C.

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

2014-01-01

428

Giant Scours on the Eel Canyon Fan  

NASA Astrophysics Data System (ADS)

Previously available surface vessel multi-beam data collected on the deep-sea fan directly down channel from the mouth of Eel Canyon off of Northern California show a train of at least 8 giant elongated asymmetric depressions that look like giant scour features. High-resolution multi-beam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m) and 1-4.5 kHz Chirp seismic reflection profiles were collected in July 2011 over two of these large topographic depressions. The surveys were conducted using an autonomous underwater vehicle (AUV) during two 17.5-hour-long dives in 2,717 to 2,533 m water depths and focused on a 4.8 km long by 4.0 km wide area. An inertial navigation system combined with a Doppler velocity sonar allowed the AUV to fly pre-programmed grids at 3 knots while maintaining an altitude of 50 m above the seafloor. Our high-resolution surveys reveal the fine-scale morphology and shallow seafloor structure of two of these giant scours. The two depressions are up to 100 m deeper than the surrounding seafloor, up to 3.4 km long (N-S axis), up to 1.8 km wide (E-W axis), and markedly asymmetric in the E-W depth profile. Distinctive arcuate scarps which slope at ~ 27° form the eastern (upstream) edge of both depressions. While the seafloor surrounding these scarps is smooth, the scarp face shows horizontal lineations that are interpreted to be outcrops of bedding surfaces. Apparently seafloor erosion focused on the face of this scarp has exposed an ~100 m thick stratigraphic section. The bathymetry also shows numerous E-W oriented ridges ~180 m in length and perpendicular to the overall trace of these scarp, resulting in a serrated or scalloped appearance. The ridges on the scarp faces have an average spacing of 70 m and are separated by intervening gullies. Whether these ridges represent more resistant joints or are a consequence of lateral variations in overriding erosive flows is unclear. The deepest areas within these depressions are immediately at the foot of the scarp where there is an abrupt transition to a nearly flat-floored sediment pond, which extends ~250 m west from the base of the scarp. From there the slope (~3°) gently rises for ~1.5 km before merging with the surrounding seafloor on the west side of each depression. Chirp data show laterally continuous reflectors on these long slopes that are parallel to the seafloor, indicating that these slopes are covered by a rather uniform drape of accumulated sediment. Collectively, these observations suggest that the depressions are massive scours that experience erosion on their upstream side and fill on their down stream side. These scours appear to be an example of features attributed to cyclic steps in large energetic marine flows. Remotely operated vehicle dives to sample within these features are planned for August 2011.

Lundsten, E.; Caress, D. W.; Paull, C. K.; Thomas, H.; Anderson, K.; Gwiazda, R.

2011-12-01

429

[Renal biopsy practice in Piedmont and Valle d'Aosta].  

PubMed

In 2010 a questionnaire was administered to the renal units of Piedmont and Valle d'Aosta to analyze their procedures for renal biopsy (RB). Seventy-eight percent of units performed RBs, 57% for more than 20 years, but only 43% performed at least 20 BRs per year. 20/21 units performed RB in an inpatient setting and 1/21 in day hospital with the patient remaining under observation the night after. Thirty-two percent did not consider a single kidney as a contraindication to RB, 59% considered it a relative contraindication and 9% considered it an absolute contraindication. In 90.5% of units there was a specific protocol for patient preparation for RB and 86% used a specific informed consent form. Ninety-five percent of units performed ultrasound-guided RB, 60% of them using needle guides attached to the probe. In 81% of units the left side was preferred; 71% put a pillow under the patient's abdomen. All units used disposable, automated or semi-automated needles. Needle size was 16G in 29%, 18G in 58%, and both 16G and 18G in 14% of units; 1 to 3 samples were drawn. One third of units had a microscope available for immediate evaluation of specimen adequacy. After RB, 86% of units kept patients in the prone position for 2-6 hours and all prescribed a period of bed rest (at least 24 hours in 90.5%). 90.5% of units followed a specific postbiopsy observation protocol consisting of blood pressure, heart rate and red blood cell measurements at different times, and urine monitoring and ultrasound control within 12-24 hours (only half of them also employing color Doppler). One third of all units discharged patients after 1 day and two thirds after 2-3 days; all prescribed abstention from effort and from antiplatelet drugs for 7-15 days. In 9 units both RB and tissue processing and examination were done in the same hospital, while 12 units sent the samples elsewhere. 76% obtained results in 2-4 days, 19% in 6-7 days, and 5% in 10-15 days. Less than 20% of the interviewed operators were fully familiar with the clauses of hospital insurance securing their activity. Use of RB is widespread in Piedmont and Valle d'Aosta but its practice shows variation between centers. PMID:23117742

Manganaro, Marco; Nebiolo, Pier Eugenio; Rollino, Cristiana; Giacchino, Franca; Savoldi, Silvana; Besso, Luca; Colla, Loredana; Amore, Alessandro; Ferro, Michela; Marazzi, Federico; Chiarinotti, Doriana; Guarnieri, Andrea; Quaglia, Marco; Manes, Massimo; Vaccaro, Valentina; Marcuccio, Cristina; Licata, Carolina; Patti, Rosaria; Mariano, Filippo; Bongi, Anna Maria; Biamino, Ercole; Boschetti, Maria Antonietta; Della Volpe, Mario; Malcangi, Ugo; Baroni, Adriana; Vagelli, Giuseppe; Costantini, Luigia; Salomone, Mario; Formica, Marco; Caramello, Elisa; Campo, Andrea; Pignone, Eugenia; Messuerotti, Alessandra; Roccatello, Dario; Stratta, Piero; Segoloni, Giuseppe; Coppo, Rosanna

2012-01-01

430

Cosmogenic 3He ages and frequency of late Holocene debris flows from Prospect Canyon, Grand Canyon, USA  

USGS Publications Warehouse

Lava Falls Rapid, which was created and is maintained by debris flows from Prospect Canyon, is the most formidable reach of whitewater on the Colorado River in Grand Canyon and is one of the most famous rapids in the world. Debris flows enter the Colorado River at tributary junctures, creating rapids. The frequency of debris flows is an important consideration when management of regulated rivers involves maintenance of channel morphology. We used cosmogenic 3He, 14C, and historical photographs to date 12 late Holocene and historic debris flows from Prospect Canyon. The highest and oldest deposits from debris flows on the debris fan yielded a 3He date of about 3 ka, which indicates predominately late Holocene aggradation of one of the largest debris fans in Grand Canyon. The deposit, which has a 25-m escarpment caused by river reworking, crossed the Colorado River and raised its base level by 30 m for an indeterminate although likely short period. We mapped depositional surfaces of 11 debris flows that occurred after 3 ka. Two deposits inset against the highest deposit yielded 3He ages of about 2.2 ka, and at least two others followed shortly afterwards. At least one of these debris flows also dammed the Colorado River. The most recent prehistoric debris flow occurred no more than 0.5 ka. The largest historic debris flow, which constricted the river by 80%, occurred in 1939. Five other debris flows occurred after 1939; these debris flows constricted the Colorado River by 35-80%. Assuming the depositional volumes of late Holocene debris flows can be modeled using a lognormal distribution, we calculated recurrence intervals of 15 to more than 2000 years for debris flows from Prospect Canyon.

Cerling, T.E.; Webb, R.H.; Poreda, R.J.; Rigby, A.D.; Melis, T.S.

1999-01-01

431

Depositional framework and genesis of Wilcox Submarine Canyon systems, Northwest Gulf Coast  

SciTech Connect

Wilcox (late Paleocene-early Eocene) slope systems of the Texas coastal plain contain two families of paleosubmarine canyons that exhibit distinctly different characteristics and stratigraphic settings: Yoakum and Lavaca type canyons occur as widely separated features within the generally retrogradational middle Wilcox interval. Four such canyons exhibit high length to width ratios, extend far updip of the contemporaneous shelf edge, were excavated deeply into paralic and coastal-plain deposits, and were filled primarily by mud. Fills consist of a lower onlapping unit and capping progradational deposits that are genetically related to deposition of the upper Wilcox fluvial-deltaic sequence. Significantly, the canyon fills correlate with widespread transgressive marine mudstones (the Yoakum shale-Sabinetown Formation and ''Big Shale''). In contrast, Lavaca-type canyons form a system of erosional features created along the rapidly prograding, unstable lower Wilcox continental margin. Comparative analysis of the two canyon system suggests a general process model for submarine canyon formation on prograding basin margins. Key elements are depositional loading of the continental margin creating instability, initiation of a large-scale slump, family of slumps, or listric bedding-plane fault creating a depression or indentation in the margin, and headward and lateral expansion of the depression by slumping and density-underflow erosion. Extent of canyon evolution varies according to time and submerged space available for maturation; short, broad canyons form on narrow shelves of actively prograding margins, and elongate mature canyons form in retrogradational or transgressive settings.

Galloway, W.F.; Dinqus, W.F.; Paige, R.E.

1988-01-01

432

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

433

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

434

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

435

Adaptive Management of Glen Canyon Dam: Two Decades of Large Scale Experimental Treatments Intended to Benefit Resources of the Colorado River in Grand Canyon, USA  

Microsoft Academic Search

Glen Canyon Dam was closed in 1963, primarily to store water for the rapidly developing southwestern United States. The dam's hydropower plant, with a generating capacity of up to 1,300 megawatts of electrical energy, was initially operated without daily peaking constraints from 1966 to 1990, resulting in daily tides on the Colorado River through Grand Canyon National Park of up

Theodore Melis

2010-01-01

436

Variation of Fracturing Pressures with Depth Near the Valles Caldera  

SciTech Connect

Hydraulic Fracturing at the Fenton Hill Hot Dry Rock Geothermal site near the Valles Caldera has yielded fracturing pressures from 14 to 81 MPa (2030 to 11,750 psi) at depths ranging from 0.7 to 4.4 km (2250 to 14,400 ft). This data can be fit to a fracture gradient of 19 MPa/km (0.84 psi/ft), except for an anomalous region between 2.6 to 3.2 km where fracturing pressures are about 20 MPa lower than estiamted using the above gradient. This anomaly coincides with a biotite granodiorite intrusive emplaced into a heterogeneous jointed metamorphic complex comprised of gneisses, schists and metavolcanic rocks. Microseismic events detected with sensitive downhole geophones suggest that shear failure is an important process during hydraulic fracturing of such jointed rock. Consequently the usual relation between minimum earth stress and fracture opening pressure, based upon classic tensile failure, cannot be used apriori; fracture opening pressure is instead a complex function of joint orientation and all three components of principal earth stress.

Dash, Zora; Murphy, Hugh

1983-12-15

437

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

438

Controlled Flooding of the Colorado River in the Grand Canyon  

NSDL National Science Digital Library

The controlled flood of the Colorado River in the Grand Canyon can be monitored in real time on the U.S. Geological Survey's (USGS) Web site. Starting on March 26 and continuing for seven days, the Bureau of Reclamation (BOR) is releasing approximately 45,000 cubic feet of water per second from Glen Canyon Dam. Line graphs of provisional stream flow data at 15 sites in Arizona are being made available in real time on the Internet via satellite telemetry technology. "This controlled flood will provide an excellent opportunity to demonstrate the usefulness of the real-time network during flooding conditions." Historical stream flow data is also available, as are calculated hydrographs, channel sand data, and detailed fact sheets on the rationale of the study and data collection methods. http://wwwdaztcn.wr.usgs.gov/flood.html

1997-01-01

439

Internal tidal currents in the Gaoping (Kaoping) Submarine Canyon  

USGS Publications Warehouse

Data from five separate field experiments during 2000-2006 were used to study the internal tidal flow patterns in the Gaoping (formerly spelled Kaoping) Submarine Canyon. The internal tides are large with maximum interface displacements of about 200??m and maximum velocities of over 100cm/s. They are characterized by a first-mode velocity and density structure with zero crossing at about 100??m depth. In the lower layer, the currents increase with increasing depth. The density interface and the along-channel velocity are approximately 90?? out-of-phase, suggesting a predominant standing wave pattern. However, partial reflection is indicated as there is a consistent phase advance between sea level and density interface along the canyon axis. ?? 2008 Elsevier B.V. All rights reserved.

Lee, I.-H.; Wang, Y.-H.; Liu, J.T.; Chuang, W.-S.; Xu, J.

2009-01-01

440

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

441

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.