For Anniversary of Orbiter Launch: Seasonal Flows in Mars Valles Marineris

NASA Image and Video Library

2015-08-10

Among the many discoveries by NASA's Mars Reconnaissance Orbiter since the mission was launched on Aug. 12, 2005, are seasonal flows on some steep slopes. These flows have a set of characteristics consistent with shallow seeps of salty water. This July 21, 2015, image from the orbiter's High Resolution Imaging Science Experiment (HiRISE) camera shows examples of these flows on a slope within Coprates Chasma, which is part of the grandest canyon system on Mars, Valles Marineris. The image covers an area of ground one-third of a mile (536 meters) wide. These flows are called recurring slope lineae because they fade and disappear during cold seasons and reappear in warm seasons, repeating this pattern every Martian year. The flows seen in this image are on a north-facing slope, so they are active in northern-hemisphere spring. The flows emanate from the relatively bright bedrock and flow onto sandy fans, where they are remarkably straight, following linear channels. Valles Marineris contains more of these flows than everywhere else on Mars combined. At any season, some are active, though on different slope aspects at different seasons. Future human explorers (and settlers?) will need water to drink, grow food, produce oxygen to breath, and make rocket fuel. Bringing all of that water from Earth would be extremely expensive, so using water on Mars is essential. Although there is plenty of water ice at high latitudes, surviving the cold winters would be difficult. An equatorial source of water would be preferable, so Valles Marineris may be the best destination. However, the chemistry of this water must be understood before betting any lives on it. http://photojournal.jpl.nasa.gov/catalog/PIA19805

Candor Chasm in Valles Marineris

NASA Technical Reports Server (NTRS)

1994-01-01

Part of Candor Chasm in Valles Marineris, Mars, from about latitude -9 degrees to -3 degrees and longitude 69 degrees to 75 degrees. Layered terrain is visible in the scene, perhaps due to a huge ancient lake. The geomorphology is complex, shaped by tectonics, mass wasting, and wind, and perhaps by water and volcanism.

Evidence for precipitation on Mars from dendritic valleys in the Valles Marineris area.

PubMed

Mangold, Nicolas; Quantin, Cathy; Ansan, Véronique; Delacourt, Christophe; Allemand, Pascal

2004-07-02

Dendritic valleys on the plateau and canyons of the Valles Marineris region were identified from Thermal Emission Imaging System (THEMIS) images taken by Mars Odyssey. The geomorphic characteristics of these valleys, especially their high degree of branching, favor formation by atmospheric precipitation. The presence of inner channels and the maturity of the branched networks indicate sustained fluid flows over geologically long periods of time. These fluvial landforms occur within the Late Hesperian units (about 2.9 to 3.4 billion years old), when Mars was thought to have been cold. Our results suggest a period of warmer conditions conducive to hydrological activity.

Automated detection of Martian water ice clouds: the Valles Marineris

NASA Astrophysics Data System (ADS)

Ogohara, Kazunori; Munetomo, Takafumi; Hatanaka, Yuji; Okumura, Susumu

2016-10-01

We need to extract water ice clouds from the large number of Mars images in order to reveal spatial and temporal variations of water ice cloud occurrence and to meteorologically understand climatology of water ice clouds. However, visible images observed by Mars orbiters for several years are too many to visually inspect each of them even though the inspection was limited to one region. Therefore, an automated detection algorithm of Martian water ice clouds is necessary for collecting ice cloud images efficiently. In addition, it may visualize new aspects of spatial and temporal variations of water ice clouds that we have never been aware. We present a method for automatically evaluating the presence of Martian water ice clouds using difference images and cross-correlation distributions calculated from blue band images of the Valles Marineris obtained by the Mars Orbiter Camera onboard the Mars Global Surveyor (MGS/MOC). We derived one subtracted image and one cross-correlation distribution from two reflectance images. The difference between the maximum and the average, variance, kurtosis, and skewness of the subtracted image were calculated. Those of the cross-correlation distribution were also calculated. These eight statistics were used as feature vectors for training Support Vector Machine, and its generalization ability was tested using 10-fold cross-validation. F-measure and accuracy tended to be approximately 0.8 if the maximum in the normalized reflectance and the difference of the maximum and the average in the cross-correlation were chosen as features. In the process of the development of the detection algorithm, we found many cases where the Valles Marineris became clearly brighter than adjacent areas in the blue band. It is at present unclear whether the bright Valles Marineris means the occurrence of water ice clouds inside the Valles Marineris or not. Therefore, subtracted images showing the bright Valles Marineris were excluded from the detection of

Mars Canyon with Los Angeles for Scale

NASA Image and Video Library

2006-03-13

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

Fogs and Clouds are a Potential Indicator of a Local Water Source in Valles Marineris

NASA Astrophysics Data System (ADS)

Leung, Cecilia W. S.; Rafkin, Scot C. R.; Stillman, David E.; McEwen, Alfred S.

2016-04-01

Recurring slope lineae (RSL) are narrow, low-albedo seasonal flow features on present-day Mars that extend incrementally down warm, steep slopes, fade when inactive, and reappear annually over multiple Mars years [1,2]. Hypothesis for the sources of volatile by which RSL are recharged include seeping water, melting shallow ice, aquifers, and vapor from the atmosphere [1-5]. About 50% of the 250+ candidate and confirmed RSL sites appear in and around Valles Marineris [3], and coincide with regions where putative morning water ice fogs may appear as imaged by the High Resolution Stereo Camera on Mars Express [6]. The presence of fog may provide clues to the water cycle within the canyon, and could elucidate the processes related to the evolution of RSL. Using a regional atmospheric model, we investigate the atmospheric dynamics in and around Valles Marineris. Our simulation results show a curious temperature structure, where the inside of the canyon appears warmer relative to the plateaus immediately outside at all times of day. Formation of fogs requires the atmosphere to be saturated. This can happen with the appropriate combination of cooling or addition of water vapor. The modeled temperature structure suggests that if water is well mixed and fog is present within the warmer canyon bottom, fog should be present on the cooler surrounding plateaus as well. This is generally not the case. Therefore, the only way to produce fog inside the canyon is to have a local water source. RSL may contribute to this atmospheric water through evaporation, or RSL may simply be a surface marker of a larger near-surface reservoir of water that can act as a source. From the modeled temperatures, we calculated the corresponding saturation vapor pressures and saturation mixing ratios to determine the amount of water vapor in the air at saturation. The observed Martian atmospheric column abundance is ~10 precipitable microns on average [7] and presents a major challenge for an

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

NASA Technical Reports Server (NTRS)

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

1993-01-01

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.

Slumps and Fog in Valles Marineris

NASA Astrophysics Data System (ADS)

Ojha, L.; Chojnacki, M.; Toigo, A. D.; McDonald, G. D.; Wolff, M. J.; Leung, C. W. S.

2016-12-01

The first spectral evidence for H2O ice clouds on Mars came from the interferometer spectrometer on board the Mariner 9 spacecraft. Water ice clouds on Mars form by freezing of atmospheric water vapor, of which the main surface source is the seasonal sublimation of the polar caps, and have been observed around the Tharsis volcanoes, Olympus Mons, Alba Patera, Valles Marineris (VM) and the southern highlands. Cloud activity in some of these regions display a seasonal trend, where the cloud area increases in warmer seasons, and decreases during colder seasons. The atmospheric hazes in VM are relatively small in areal extent, confined within canyon topography, and are difficult to replicate in models of global or regional vapor transport, indicating that they may be locally sourced. This distinguishes the VM hazes from the global-scale clouds. Spectral data from the Planetary Fourier Spectrometer onboard the Mars Express orbiter have been reported as consistent with water ice in the atmospheric fog, however results from Mars Express favored dust as responsible for low-elevation hazes. Here we report observations and spectroscopic analyses of low elevation haze in Juventae Chasma, which are spatially correlated with locations of seasonal flows thought to be caused by briny liquid water. Furthermore, we report the seasonality of the haze and explore its potential role in the creation of contemporary mass-wasting features on Mars.

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

USGS Publications Warehouse

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

2010-01-01

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.

Impact craters and landslide volume distribution in Valles Marineris, Mars

NASA Astrophysics Data System (ADS)

De Blasio, Fabio

2014-05-01

The landslides in the wide gorge system of Valles Marineris (Mars) exhibit volumes of the or-der of several hundred 1,000 km3 and runouts often in the excess of 80 km. Most landslides have occurred at the borders of the valleys, where the unbalanced weight of the 5-8 km high headwalls has been evidently sufficient to cause instability. Previous analysis has shown that the mechanical conditions of instability would not have been reached without external triggering fac-tors, if the wallslope consisted of intact rock. Among the factors that have likely promoted instability, we are currently analyzing: i) the possibility of rock weakening due to weathering; ii) the alternation of weak layers within more massive rock; weak layers might for example due to evaporites, the possible presence of ice table at some depth, or water; iii) weakening due to impact damage prior to the formation of Valles Marineris; studies of impact craters on Earth show that the volumes of damaged rock extends much deeper than the crater itself; iv) direct triggering of a landslide due to the seismic waves generated by a large meteoroid impact in the vicinity, and v) direct triggering of a landslide con-sequent to impact at the headwall, with impulsive release of momentum and short but intense increase of the triggering force. We gathered a large database for about 3000 Martian landslides that allow us to infer some of their statistical properties supporting our analyses, and especially to discriminate among some of the above listed predisposing and triggering factors. In particular, we analyse in this contribution the frequency distribution of landslide volumes starting from the assumption that these events are controlled by the extent of the shock damage zones. Relative position of the impact point and damage zones with respect to the Valles Marineris slopes could in fact control the released volumes. We perform 3D slope stability analy-sis under different geometrical constraints (e.g. crater

Lakes in Valles Marineris

NASA Astrophysics Data System (ADS)

Lucchitta, Baerbel K.

2010-10-01

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

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

NASA Astrophysics Data System (ADS)

Schultz, R. A.

1989-10-01

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.

Are there carbonate deposits in the Valles Marineris, Mars?

NASA Technical Reports Server (NTRS)

Nedell, Susan S.; Mckay, Christopher P.

1989-01-01

The precipitation of 30 mbar of Martian atmosphere CO2 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 CO2 would have accumulated in such Martian lakes as temperature fell, and the presence of an insulating ice cover would have allowed liquid water to exist.

Mars Odyssey View of Morning Clouds in Canyon

NASA Image and Video Library

2016-04-05

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

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

NASA Technical Reports Server (NTRS)

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

2001-01-01

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.

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)

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

1999-01-01

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

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)

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

1999-06-01

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

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

NASA Technical Reports Server (NTRS)

Frey, Herbert V.; Schultz, Richard A.

1990-01-01

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.

The Layer Cake Walls of Valles Marineris

NASA Technical Reports Server (NTRS)

2007-01-01

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

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

NASA Technical Reports Server (NTRS)

1998-01-01

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.

Sites with Seasonal Streaks on Slopes in Mars Canyons

NASA Image and Video Library

2016-07-07

Blue dots on this map indicate sites of recurring slope lineae (RSL) in part of the Valles Marineris canyon network on Mars. RSL are seasonal dark streaks regarded as the strongest evidence for the possibility of liquid water on the surface of modern Mars. The area mapped here has the highest density of known RSL on the Red Planet. The RSL were identified by repeated observations of the sites using the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Map colors represent elevation, where red is high and blue is low. Valles Marineris is the largest canyon system in the solar system. The region shown here includes Melas Chasma and Coprates Chasma, in the central and eastern portions of Valles Marineris. The mapped area extends about 1,500 miles (2,400 kilometers) east to west and about 280 miles (450 kilometers) north to south, at latitudes from 9 to 17 degrees south of Mars' equator. The base map uses data from the Mars Orbiter Camera and Mars Orbiter Laser Altimeter of NASA's Mars Global Surveyor mission. RSL extend downslope during a warm season, fade in the colder part of the year, and repeat the process in a subsequent Martian year. A study of 41 RSL sites in this canyon area, published July 7, 2016, provides support for the notion that significant amounts of near-surface water can be found on modern Mars, though the work also indicates that puzzles remain unsolved in understanding how these seasonal features form. Each site includes anywhere from a few to more than 1,000 individual "lineae." http://photojournal.jpl.nasa.gov/catalog/PIA20756

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

NASA Astrophysics Data System (ADS)

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

2009-12-01

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 μm, 1.9 μm, and a narrow band at 2.2 μm. 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

Using Terrestrial Sulfate Efflorescences as an Analogue of Hydrated Sulfate Formation in Valles Marineris on Mars

NASA Astrophysics Data System (ADS)

Smith, P. C.; Szynkiewicz, A.

2015-12-01

Hydrated sulfate minerals provide conclusive evidence that a hydrologic cycle was once active on the surface of Mars. Two classes of hydrated sulfate minerals have been detected by robotic instruments on Mars: monohydrated sulfate minerals comprised of kieserite and gypsum, and various polyhydrated sulfates with Fe-Ca-Na-Mg-rich compositions. These minerals are found in various locations on Mars, including large surface exposures in valley settings of Valles Marineris. However, the sulfate sources and formation mechanisms of these minerals are not yet well understood.Recently, it has been suggested that the sulfate minerals in Valles Marineris might have formed in a manner similar to sulfate efflorescences found in dry environments on Earth. In this study, we use sulfate effloresences from the Rio Puerco Watershed, New Mexico as a terrestrial analogue to assess major factors that might have led to deposition of sulfate minerals in Valles Marineris. In different seasons indicative of dry and wet conditions, we collected field photographs and sediment samples for chemical and stable isotopic analyses (sulfur content, δ34S) to determine major sources of sulfate ions for efflorescences and to assess how the seasonal changes in surface/groundwater activity affect their formation. Preliminary sulfur isotope results suggest that oxidation of bedrock sulfides (0.01-0.05 wt. S %) is a major source of sulfate ion for efflorescences formation because their δ34S varied in negative range (-28 to -20‰) similar to sulfides (average -32‰). Using field photographs collected in Oct 2006, Feb and Nov 2012, May 2013, Mar and Oct 2014, we infer that the highest surface accumulation of sulfate efflorescences in the studied analog site was observed after summer monsoon seasons when more water was available for surface and subsurface transport of solutes from chemical weathering. Conversely, spring snow melt led to enhanced dissolution of sulfate efflorescences.

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

NASA Astrophysics Data System (ADS)

Imre, B.

2003-04-01

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

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

NASA Technical Reports Server (NTRS)

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

1993-01-01

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.

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

NASA Technical Reports Server (NTRS)

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

1995-01-01

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.

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

USGS Publications Warehouse

McEwen, A.S.

1989-01-01

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

Martian tension fractures and the formation of grabens and collapse features at Valles Marineris

NASA Technical Reports Server (NTRS)

Tanaka, K. L.; Golombek, M. P.

1989-01-01

Simple models of the Martian crust are summarized that predict extensional deformation style on the basis of depth, material friction and strength, and hydraulic conditions appropriate to the planet. These models indicate that tension fractures may be common features on Mars, given adequate differential stress conditions. Examples of tension fractures on Mars inferred from morphological criteria are examined based on the probable geologic conditions in which they formed and on model constraints. It is proposed that the grabens and collapse features of Valles Marineris are controlled by tension fractures in intact basement rocks that lie below impact ejecta.

Analysis of Fault Lengths Across Valles Marineris, Mars

NASA Astrophysics Data System (ADS)

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

1996-03-01

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.

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

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

Characteristics of the numerous and widespread recurring slope lineae (RSL) in Valles Marineris, Mars

NASA Astrophysics Data System (ADS)

Stillman, David E.; Michaels, Timothy I.; Grimm, Robert E.

2017-03-01

Recurring slope lineae (RSL) are narrow (0.5-5 m) dark features on Mars that incrementally lengthen down steep slopes, fade in colder seasons, and recur annually. These traits suggest that liquid water is flowing in the shallow subsurface of Mars today. Here we describe High Resolution Imaging Science Experiment (HiRISE) observations of RSL within Valles Marineris (VM). We have identified 239 candidate and confirmed RSL sites within all the major canyons of VM, with the exception of Echus Chasma. About half of all the globally known RSL locations occur within VM and the areal density of RSL on Coprates Montes appears to be the greatest on the planet. VM RSL are heterogeneously distributed, as they are primarily clustered in certain areas while being conspicuously absent in other locations that appear otherwise favorable. RSL have been found on many of the interior layered deposits (ILDs) within VM. Such ILD RSL appear to traverse bedrock, instead of regolith like all other RSL. Forty-six of the VM RSL sites show incremental lengthening and exhibit similar behavior in most of the canyons of VM, but the RSL duration at one site in Juventae Chasma is significantly reduced. Furthermore, the lengthening seasonality depends solely on slope orientation, with typical VM RSL on a given slope lengthening for ∼42-74% of a Mars year. There are always RSL lengthening within VM, regardless of the season. If RSL are caused by water, such a long active season at hundreds of VM RSL sites suggests that an appreciable source of water must be recharging these RSL. Thermophysical modeling indicates that a melting temperature range of ∼246 - 264 K is needed to reproduce the seasonal phenomenology of the VM RSL, suggesting the involvement of a brine consisting of tens of wt% salt. The mechanism(s) by which RSL are recharged annually remain uncertain. Overall, gaining a better understanding of how RSL form and recur can benefit the search for extant life on Mars and could provide

Mechanical conditions and modes of paraglacial deep-seated gravitational spreading in Valles Marineris, Mars

NASA Astrophysics Data System (ADS)

Makowska, Magdalena; Mège, Daniel; Gueydan, Frédéric; Chéry, Jean

2016-09-01

Deep-seated gravitational spreading (DSGS) affects the slopes of formerly glaciated mountain ridges. On Mars, DSGS has played a key role in shaping the landforms of the giant Valles Marineris troughs. Though less spectacular, DSGS is common in terrestrial orogens, where understanding its mechanics is critical in the light of the ongoing climate change because it is a potential source of catastrophic landslides in deglaciated valleys. We conducted parametric numerical studies in order to identify important factors responsible for DSGS initiation. DSGS models are computed using an elastoviscoplastic finite element code. Using ADELI's software, we reproduce topographic ridge spreading under the effect of valley unloading. Two types of spreading topographic ridges are investigated, homogeneous or with horizontal rheological layering. We find that gravitational instabilities are enhanced by high slopes, which increase gravitational stress, and low friction and cohesion, which decrease yield stress. In the unlayered ridge, instability is triggered by glacial unloading with plastic strain concentration inside the ridge and at the base of the high slopes. Vertical fractures develop in the upper part of the slope, potentially leading to fault scarps. Ridge homogeneity promotes a deformation mode controlled by uphill-facing normal faulting and basal bulging. In the second case, the ridge encompasses horizontal geological discontinuities that induce rock mass anisotropy. Discontinuity located at the base of the slope accumulates plastic strain, leading to the formation of a sliding plane evolving into a landslide. The presence of a weak layer at ridge base therefore promotes another slope deformation mode ending up with catastrophic failure. Mechanical conditions and slope height being equal, these conclusions can probably be extrapolated to Earth. Compared with Mars, DSGS on Earth is inhibited because terrestrial topographic gradients are lower than in Valles Marineris, an

Valles Marineris as a Cryokarstic Structure Formed by a Giant Dyke System: Support From New Analogue Experiments

NASA Astrophysics Data System (ADS)

Ozeren, M. S.; Sengor, A. M. C.; Acar, D.; Ülgen, S. C.; Onsel, I. E.

2014-12-01

Valles Marineris is the most significant near-linear depression on Mars. It is some 4000 km long, up to about 200 km wide and some 7 km deep. Although its margins look parallel at first sight, the entire structure has a long spindle shape with significant enlargement in its middle (Melas Chasma) caused by cuspate slope retreat mechanisms. Farther to its north is Hebes Chasma which is an entirely closed depression with a more pronounced spindle shape. Tithonium Chasma is a parallel, but much narrower depression to its northeast. All these chasmae have axes parallel with one another and such structures occur nowhere else on Mars. A scabland surface exists to the east of the Valles Marineris and the causative water mass seems to have issued from it. The great resemblance of these chasmae on mars to poljes in the karstic regions on earth have led us to assume that they owed their existence to dissolution of rock layers underlying them. We assumed that the dissolving layer consisted of water ice forming substantial layers, in fact entirely frozen seas of several km depth. We have simulated this geometry by using bentonite and flour layers (in different experiments) overlying layers of ice in which a resistant coil was used to simulate a dyke. We used different thicknesses of bentonite and flour overlying ice layers again of various thicknesses. The flour seems to simulate the Martian crust better because on Mars, g is only about 3/8ths of its value on Earth, so (for equal crustal density) the depth to which the cohesion term C remains important in the Mohr-Coulomb shear failure criterion is about 8/3 times greater. As examples we show two of those experiments in which both the rock analogue and ice layers were of 1.5 cm. thick. Perfect analogues of the Valles Marineris formed above the dyke analogue thermal source complete with the near-linear structure, overall flat spindle shape, cuspate margins, a central ridge, parallel side faults, parallel depressions resembling

Hydrated mineral stratigraphy of Ius Chasma, Valles Marineris

USGS Publications Warehouse

Roach, L.H.; Mustard, J.F.; Swayze, G.; Milliken, R.E.; Bishop, J.L.; Murchie, S.L.; Lichtenberg, K.

2010-01-01

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

The Evolution of Juventae Chasma, Valles Marineris, Mars: Progressive Collapse and Sedimentation

NASA Astrophysics Data System (ADS)

Fueten, F.; Novakovic, N.; Stesky, R.; Flahaut, J.; Hauber, E.; Rossi, A. P.

2017-11-01

Juventae Chasma is an isolated chasm located north of the interconnected chasms within Valles Marineris. It contains four separate interior layered deposit (ILD) mounds. We have combined layer measurements, as well as mineralogical data of the mounds with topographic data of the remaining chasm and the surrounding plateau. Our observations indicate that the chasm underwent a complex geological history. We suggest that individual ILD mounds are not contemporaneous with each other and a series of progressive collapses enlarged an initially smaller chasm to its current shape. ILDs were deposited in a lacustrine setting, and the time of ILD deposition was limited. Basin collapse and chasm enlargement continued beyond the time of ILD deposition and thus were not driven by sediment load. Glacial processes appear to have played a role in the late, postlacustrine history of the chasm. We present a simplified model that highlights some of the complexity of the chasm evolution, but acknowledge that the true history is undoubtedly more complicated.

Role of Clay Minerals in Long-Distance Transport of Landslides in Valles Marineris, Mars

NASA Astrophysics Data System (ADS)

Watkins, J.; Ehlmann, B. L.; Yin, A.

2014-12-01

Long-runout (> 50 km) subaerial landslides are rare on Earth, but are common features episodically shaping Mars' Valles Marineris (VM) trough system over the past 3.5 billion years. They display two end-member morphologies: a thick-skinned inner zone, characterized by fault-bounded, rotated blocks near their source region, and a thin-skinned, exceptionally long-runout outer zone, characterized by thin sheets spreading over 10s of km across the trough floor. Four decades of studies on the latter have resulted in two main competing hypotheses to explain their long-distance transport: (1) movement of landslides over layers of trapped air or soft materials containing ice or snow, enabling basal lubrication, and (2) fluidization of landslide materials with or without the presence of water and volatiles. To address this issue, we examine the mineralogic composition of landslides across VM using Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) near-infrared spectral data analysis coupled with detailed geologic mapping and morphometric analysis of satellite images. Our survey reveals a general correlation between transport distance, significant lateral spreading, and the presence of hydrated silicates among VM landslides. Given that smectite clay absorbs water into its layered crystal structure and can reduce the friction coefficient by a factor of three v. that of dry rocks, these results suggest that hydrated silicates played a decisive role in facilitating long-runout landslide transport in VM. We propose that, concurrent with downslope failure and sliding of broken trough-wall rock, frontal landslide masses overrode and entrained hydrated-silicate-bearing trough-floor deposits, lubricating the basal sliding zones and permitting the landslide outer zones to spread laterally while moving forward over the low-friction surface. The key participation of hydrated silicates in episodic, sustained landslide activity throughout the canyon implies that clay minerals

Martian canyons and African rifts: Structural comparisons and implications

NASA Technical Reports Server (NTRS)

Frey, H. V.

1978-01-01

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

Characterization of Layered Deposits inside Valles Marineris

NASA Technical Reports Server (NTRS)

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

2005-01-01

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

High View of Melas

NASA Image and Video Library

2006-03-13

Soaring high above Valles Marineris, the Grand Canyon of Mars, viewers look down and catch a sight resembling parts of the desert West of the United States, but on a vastly greater scale. Here the canyon averages over a hundred miles wide.

Mariner 9 Anniversary/Landslides on Mars Released 13 November 2002

NASA Image and Video Library

2002-11-15

This canyon system imaged here by NASA Mars Odyssey was named Valles Marineris in honor of its discoverer, NASA Mariner 9 spacecraft. The image covers a portion of the canyon system called Melas Chasma. http://photojournal.jpl.nasa.gov/catalog/PIA04003

Geometric comparison of deep-seated gravitational spereading features on Mars (Coprates Chasma, Valles Marineris) and Earth (Ornak, Tatra Mountains)

NASA Astrophysics Data System (ADS)

Kromuszczyńska, O.; Mège, D.

2014-04-01

Uphill-facing normal faults scarps and crestal grabens, which are characteristic of deep-seated gravitational spreading (DSGS) of topographic ridges, are described in Coprates Chasma in Valles Marineris, Mars, and Ornak ridge and compared. The vertical offset of normal faults in the Martian instances varies from 40 to 1000 meters, with an average of 300 meters. The terrestrial faults offset is between few teens of centimeters up to 34 meters with an average of 10 meters. The values of horizontal displacement in Coprates Chasma vary from 10 to 680 meters, and at Ornak are in a range between 1 and 20 meters. Such difference corresponds with the difference of ridges scale and is due to the topographic gradient which is one order of magnitude higher on Mars than on Earth.

Investigating Mars: Tithonium Chasma

NASA Image and Video Library

2018-02-05

This VIS image shows part of the central region of Tithonium Chasma. The steep wall of the canyon is visible at the top of the image. The top of the canyon walls are layered, mostly likely by numerous volcanic flows. This material is more resistant and forms the ridges extending down the canyon walls. A large landslide deposit covers the right side of the image. An eroded mound on the floor of the canyon exists at the bottom left of the image. The initial formation of the mound was possibly created of air fall of dust, sand, and volcanic materials and water lain materials. Tithonium Chasma is at the western end of Valles Marineris. Valles Marineris is over 4000 kilometers long, wider than the United States. Tithonium Chasma is almost 810 kilometers long (499 miles), 50 kilometers wide and over 6 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the

Investigating Mars: Ius Chasma

NASA Image and Video Library

2018-03-02

Ius Chasma is unique from the other chasmata of Valles Marineris in possessing mega gullies on both sides of the chasma. The largest mega gullies are located in Sinai Planum, dissecting those plains and emptying into the canyon. These mega gullies are called Louros Valles. Mega gullies are thought to be sapping channels caused by groundwater flow and erosion. The Earth analog is springs - water that flows underground and then breaches the surface creating channels. The morphology of the Mars gullies mirrors terrestrial springs. The channel is fairly uniform in width and the "head" of the channel is rounded like an amphitheater. The channel lengthens by erosion at the "head" backwards as the surface where the spring emerges is undercut. For Mars it is theorized that subsurface water would stay liquid due to underground heating. The channels in this image are parts of the two largest mega gullies. Note how every channel head is the amphitheater bowl shape. Ius Chasma is at the western end of Valles Marineris, south of Tithonium Chasma. Valles Marineris is over 4000 kilometers long, wider than the United States. Ius Chasma is almost 850 kilometers long (528 miles), 120 kilometers wide and over 8 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying layered materials. There are many features that indicate flowing and standing water played a part in the chasma formation. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS

Investigating Mars: Ius Chasma

NASA Image and Video Library

2018-03-01

Ius Chasma is unique from the other chasmata of Valles Marineris in possessing mega gullies on both sides of the chasma. The largest mega gullies are located in Sinai Planum, dissecting those plains and emptying into the canyon. These mega gullies are called Louros Valles. Mega gullies are thought to be sapping channels caused by groundwater flow and erosion. The Earth analog is springs - water that flows underground and then breaches the surface creating channels. The morphology of the Mars gullies mirrors terrestrial springs. The channel is fairly uniform in width and the "head" of the channel is rounded like an amphiteater. The channel lengthens by erosion at the "head" backwards as the surface where the spring emerges is undercut. For Mars it is theorized that subsurface water would stay liquid due to underground heating. The "X" in the lower half of the image and the channel at the very bottom are parts of the two largest mega gullies. Ius Chasma is at the western end of Valles Marineris, south of Tithonium Chasma. Valles Marineris is over 4000 kilometers long, wider than the United States. Ius Chasma is almost 850 kilometers long (528 miles), 120 kilometers wide and over 8 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying layered materials. There are many features that indicate flowing and standing water played a part in the chasma formation. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR

Possible Sulfate Deposits in West Melas Chasma

NASA Image and Video Library

2016-05-04

Melas Chasma is the widest segment of Valles Marineris, the largest canyon in the Solar System as seen by Mars Reconnaissance Orbiter spacecraft. In this region, hydrated sulfate salts have been detected.

Investigating Mars: Tithonium Chasma

NASA Image and Video Library

2018-02-06

This VIS image shows part of Tithonium Chasma. The ridge visible at the top of the image is not the top of the canyon. The top of the canyon is off the image to the north. A lobate "tongue" visible between the ridge and the top of the canyon is the deposit left by a landslide event. This material is more resistant and forms the ridges extending down the canyon walls. Eroded materials cover much of the canyon floor. The initial formation of layered floor desposits was possibly created of air fall of dust, sand, and volcanic materials and water lain materials. The weathering of these deposits is probably by the wind. Loose sand and dust can be seen in other portions of this image. Tithonium Chasma is at the western end of Valles Marineris. Valles Marineris is over 4000 kilometers long, wider than the United States. Tithonium Chasma is almost 810 kilometers long (499 miles), 50 kilometers wide and over 6 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying layered materials. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels

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

NASA Technical Reports Server (NTRS)

Patton, Peter C.

1990-01-01

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

Western Candor Chasma - Layers exposed near the middle

NASA Technical Reports Server (NTRS)

1998-01-01

One of the most striking discoveries of the Mars Global Surveyor mission has been the identification of thousands of meters/feet of layers within the wall rock of the enormous martian canyon system, Valles Marineris.

Valles Marineris was first observed in 1972 by the Mariner 9 spacecraft, from which the troughs get their name: Valles--valleys, Marineris--Mariner.

Some hints of layering in both the canyon walls and within some deposits on the canyon floors were seen in Mariner 9 and Viking orbiter images from the 1970s. The Mars Orbiter Camera on board Mars Global Surveyor has been examining these layers at much higher resolution than was available previously.

MOC images led to the realization that there are layers in the walls that go down to great depths. An example of the wall rock layers can be seen in MOC image 8403, shown above (C).

MOC images also reveal amazing layered outcrops on the floors of some of the Valles Marineris canyons. Particularly noteworthy is MOC image 23304 (D, above), which shows extensive, horizontally-bedded layers exposed in buttes and mesas on the floor of western Candor Chasma. These layered rocks might be the same material as is exposed in the chasm walls (as in 8403--C, above), or they might be rocks that formed by deposition (from water, wind, and/or volcanism) long after Candor Chasma opened up.

In addition to layered materials in the walls and on the floors of the Valles Marineris system, MOC images are helping to refine our classification of geologic features that occur within the canyons. For example, MOC image 25205 (E, above), shows the southern tip of a massive, tongue-shaped massif (a mountainous ridge) that was previously identified as a layered deposit. However, this MOC image does not show layering. The material has been sculpted by wind and mass-wasting--downslope movement of debris--but no obvious layers were exposed by these processes.

Valles Marineris a fascinating region on Mars that holds much

Candor Chasma - Massive (non-layered) material expos

NASA Technical Reports Server (NTRS)

1998-01-01

One of the most striking discoveries of the Mars Global Surveyor mission has been the identification of thousands of meters/feet of layers within the wall rock of the enormous martian canyon system, Valles Marineris.

Valles Marineris was first observed in 1972 by the Mariner 9 spacecraft, from which the troughs get their name: Valles--valleys, Marineris--Mariner.

Some hints of layering in both the canyon walls and within some deposits on the canyon floors were seen in Mariner 9 and Viking orbiter images from the 1970s. The Mars Orbiter Camera on board Mars Global Surveyor has been examining these layers at much higher resolution than was available previously.

MOC images led to the realization that there are layers in the walls that go down to great depths. An example of the wall rock layers can be seen in MOC image 8403, shown above (C).

MOC images also reveal amazing layered outcrops on the floors of some of the Valles Marineris canyons. Particularly noteworthy is MOC image 23304 (D, above), which shows extensive, horizontally-bedded layers exposed in buttes and mesas on the floor of western Candor Chasma. These layered rocks might be the same material as is exposed in the chasm walls (as in 8403--C, above), or they might be rocks that formed by deposition (from water, wind, and/or volcanism) long after Candor Chasma opened up.

In addition to layered materials in the walls and on the floors of the Valles Marineris system, MOC images are helping to refine our classification of geologic features that occur within the canyons. For example, MOC image 25205 (E, above), shows the southern tip of a massive, tongue-shaped massif (a mountainous ridge) that was previously identified as a layered deposit. However, this MOC image does not show layering. The material has been sculpted by wind and mass-wasting--downslope movement of debris--but no obvious layers were exposed by these processes.

Valles Marineris a fascinating region on Mars that holds much

Crustal Fractures of Ophir Planum

NASA Technical Reports Server (NTRS)

2002-01-01

(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

Coprates Chasma

NASA Image and Video Library

2002-06-26

This image from NASA Mars Odyssey spacecraft, which displays clearly the contrast between bedrock, sand, and dust surfaces, covers a portion of Coprates Chasma, part of the Valles Marineris system of canyons that stretch for thousands of kilometers.

Ophir Planum

NASA Image and Video Library

2002-07-17

This image from NASA Mars Odyssey spacecraft shows a region of Mars called Ophir Planum. The Valles Marineris system of canyons that stretch for thousands of kilometers across Mars are located just south of the area covered in the image.

Melas Chasma Deposits

NASA Image and Video Library

2003-01-09

Erosion of the interior layered deposits of Melas Chasma, part of the huge Valles Marineris canyon system, has produced cliffs with examples of spur and gulley morphology and exposures of finely layered sediments, as seen in this NASA Mars Odyssey image.

Investigating Mars: Tithonium Chasma

NASA Image and Video Library

2018-02-09

Tithonium Chasma has numerous large landslide deposits. The resistant material of the plateau surface forms the linear ridges of the canyon wall. Large landslides have changed the walls and floor of the canyon. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. This VIS image shows the result of this type of landslide. Tithonium Chasma is at the western end of Valles Marineris. Valles Marineris is over 4000 kilometers long, wider than the United States. Tithonium Chasma is almost 810 kilometers long (499 miles), 50 kilometers wide and over 6 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying layered materials. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR

Investigating Mars: Ius Chasma

NASA Image and Video Library

2018-02-19

The VIS image shows part of the western end of Ius Chasma. Both the north and south canyon walls are visible in this image. At the top of the frame paired faults have created a graben. On the southern face of the canyon, several linear faults parallel the graben. These faults are part of the tectonic formation of Valles Marineris. Landslides on both walls created deposits on the crater floor. The easiest to identify is the lobate margin at the right side of the images. Lobate margins and radial surface grooves are common features in low volume landslides. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Ius Chasma is at the western end of Valles Marineris, south of Tithonium Chasma. Valles Marineris is over 4000 kilometers long, wider than the United States. Ius Chasma is almost 850 kilometers long (528 miles), 120 kilometers wide and over 8 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the

Investigating Mars: Melas Chasma

NASA Image and Video Library

2017-11-28

Melas Chasma is part of the largest canyon system on Mars, Valles Marineris. At only 563 km long (349 miles) it is not the longest canyon, but it is the widest. Located in the center of Valles Marineris, it has depths up to 9 km below the surrounding plains, and is the location of many large landslide deposits, as will as layered materials and sand dunes. There is evidence of both water and wind action as modes of formation for many of the interior deposits. This VIS image highlights the extent of layered materials within the canyon. The image is located on the mid elevations on the south side of the canyon. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 10813 Latitude: -13.1037 Longitude: 289.967 Instrument: VIS Captured: 2004-05-22 16:09 https://photojournal.jpl.nasa.gov/catalog/PIA22129

Investigating Mars: Ius Chasma

NASA Image and Video Library

2018-02-20

Continuing eastward along Ius Chasma, this section of the canyon floor has been completely filled by blocky deposits from large volume landslides. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Ius Chasma is at the western end of Valles Marineris, south of Tithonium Chasma. Valles Marineris is over 4000 kilometers long, wider than the United States. Ius Chasma is almost 850 kilometers long (528 miles), 120 kilometers wide and over 8 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying layered materials. There are many features that indicate flowing and standing water played a part in the chasma formation. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR

Investigating Mars: Tithonium Chasma

NASA Image and Video Library

2018-02-07

This VIS image shows part of the floor of Tithonium Chasma. Eroded materials cover most of the image. The initial formation of layered floor deposits was possibly created of air fall of dust, sand, and volcanic materials and water lain materials. The weathering of these deposits is probably by the wind. The bottom part of the image has complex, hummocky material, probably very old landslide deposits. At the top of the image is a large mound of material that has been eroded mainly by wind action. The overlapping of these surfaces indicates a long history of modication of Tithonium Chasma. Tithonium Chasma is at the western end of Valles Marineris. Valles Marineris is over 4000 kilometers long, wider than the United States. Tithonium Chasma is almost 810 kilometers long (499 miles), 50 kilometers wide and over 6 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying layered materials. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the

Investigating Mars: Tithonium Chasma

NASA Image and Video Library

2018-02-13

This VIS image of Tithonium Chasma shows the canyon wall at the top of the frame, a series of landslide deposits in the middle, and an eroded mound of materials at the bottom. The mound has been eroded, most likely by wind action. Tithonium Chasma has numerous large landslide deposits. The resistant material of the plateau surface forms the linear ridges of the canyon wall. Large landslides have changed the walls and floor of the canyon. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Tithonium Chasma is at the western end of Valles Marineris. Valles Marineris is over 4000 kilometers long, wider than the United States. Tithonium Chasma is almost 810 kilometers long (499 miles), 50 kilometers wide and over 6 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying layered materials. The Odyssey

Chryse Outflow Channel

NASA Image and Video Library

1998-06-08

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 NASA's 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. http://photojournal.jpl.nasa.gov/catalog/PIA00418

Investigating Mars: Ius Chasma

NASA Image and Video Library

2018-02-19

Continuing eastward along Ius Chasma, this image shows the eastern section of the large landslide deposit seen in yesterday's post. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Ius Chasma is at the western end of Valles Marineris, south of Tithonium Chasma. Valles Marineris is over 4000 kilometers long, wider than the United States. Ius Chasma is almost 850 kilometers long (528 miles), 120 kilometers wide and over 8 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying layered materials. There are many features that indicate flowing and standing water played a part in the chasma formation. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has

Investigating Mars: Melas Chasma

NASA Image and Video Library

2017-11-30

Melas Chasma is part of the largest canyon system on Mars, Valles Marineris. At only 563 km long (349 miles) it is not the longest canyon, but it is the widest. Located in the center of Valles Marineris, it has depths up to 9 km below the surrounding plains, and is the location of many large landslide deposits, as will as layered materials and sand dunes. There is evidence of both water and wind action as modes of formation for many of the interior deposits. Today's image of the southern section of the canyon shows a large region of sand dunes. The presence of dunes indicates wind action as the most recent geologic process modifying the canyon. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 18513 Latitude: -12.752 Longitude: 288.597 Instrument: VIS Captured: 2006-02-15 15:24 https://photojournal.jpl.nasa.gov/catalog/PIA22131

Investigating Mars: Melas Chasma

NASA Image and Video Library

2017-12-04

Melas Chasma is part of the largest canyon system on Mars, Valles Marineris. At only 563 km long (349 miles) it is not the longest canyon, but it is the widest. Located in the center of Valles Marineris, it has depths up to 9 km below the surrounding plains, and is the location of many large landslide deposits, as will as layered materials and sand dunes. There is evidence of both water and wind action as modes of formation for many of the interior deposits. Today's image contains a large region of dunes between the canyon cliff face and the large ridge of material at the mid-elevation of the canyon. Fine materials have been concentrated into the dunes. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 26525 Latitude: -11.3125 Longitude: 285.57 Instrument: VIS Captured: 2007-12-07 07:23 https://photojournal.jpl.nasa.gov/catalog/PIA22134

Investigating Mars: Tithonium Chasma

NASA Image and Video Library

2018-02-16

In this VIS image of Tithonium Chasma both sides of the chasma are visible. In this narrow and deep part of the chasma exist both large, chaotic block landslide deposits with smaller lobate shaped landslide deposits on top. Tithonium Chasma has numerous large landslide deposits. The resistant material of the plateau surface forms the linear ridges of the canyon wall. Large landslides have changed the walls and floor of the canyon. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Tithonium Chasma is at the western end of Valles Marineris. Valles Marineris is over 4000 kilometers long, wider than the United States. Tithonium Chasma is almost 810 kilometers long (499 miles), 50 kilometers wide and over 6 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying layered materials. The Odyssey spacecraft has

Investigating Mars: Tithonium Chasma

NASA Image and Video Library

2018-02-08

Tithonium Chasma has numerous large landslide deposits. At the bottom of this VIS image is the high plateau between Tithonium Chasma and Ius Chasma (off the bottom of the frame). The resistant material of the plateau surface forms the linear ridges of the canyon wall. Erosion of the walls cover the lower slopes. Large landslides have changed the walls and floor of the canyon. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. As the landslide material reaches the canyon bottom it spreads out and eventually comes to rest. The edge of the deposit is lobate, and may be affected by running up against pre-existing features on the canyon floor. Most Martian landslide have radial grooves on the slide surface. Tithonium Chasma is at the western end of Valles Marineris. Valles Marineris is over 4000 kilometers long, wider than the United States. Tithonium Chasma is almost 810 kilometers long (499 miles), 50 kilometers wide and over 6 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying layered

Topography of Valles Marineris: Implications for erosional and structural history

NASA Technical Reports Server (NTRS)

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

1994-01-01

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

Investigating Mars: Tithonium Chasma

NASA Image and Video Library

2018-02-14

This VIS image of Tithonium Chasma shows the canyon wall at the top of the frame and the cliff face of the opposite side of the canyon at the bottom of the image. Most of the floor has been covered with the deposits of large volume landslides. Near the top-right portion of the canyon wall several smaller lobate landslide deposits are visible. Tithonium Chasma has numerous large landslide deposits. The resistant material of the plateau surface forms the linear ridges of the canyon wall. Large landslides have changed the walls and floor of the canyon. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Tithonium Chasma is at the western end of Valles Marineris. Valles Marineris is over 4000 kilometers long, wider than the United States. Tithonium Chasma is almost 810 kilometers long (499 miles), 50 kilometers wide and over 6 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of

Investigating Mars: Melas Chasma

NASA Image and Video Library

2017-11-27

Melas Chasma is part of the largest canyon system on Mars, Valles Marineris. At only 563 km long (349 miles) it is not the longest canyon, but it is the widest. Located in the center of Valles Marineris, it has depths up to 9 km from the surrounding plains, and is the location of many large landslide deposits, as will as layered materials and sand dunes. There is evidence of both water and wind action as modes of formation for many of the interior deposits. This VIS image shows layered materials and sand dunes. The image is located on the mid elevations on the south side of the canyon. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 10838 Latitude: -12.7865 Longitude: 288.837 Instrument: VIS Captured: 2004-05-24 17:32 https://photojournal.jpl.nasa.gov/catalog/PIA22128

Investigating Mars: Tithonium Chasma

NASA Image and Video Library

2018-02-12

In this VIS image a complex region of multiple overlapping landslide deposits fills most the the frame. The very top layer has the lobate edges and radial surface grooves of a low volume slide. It appears to be the top of a complex layering of materials. It is possible that all the lower layers are landslides as well. Whether the layers formed very close in time of over thousands of years can not be determined in the image. Tithonium Chasma has numerous large landslide deposits. The resistant material of the plateau surface forms the linear ridges of the canyon wall. Large landslides have changed the walls and floor of the canyon. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Tithonium Chasma is at the western end of Valles Marineris. Valles Marineris is over 4000 kilometers long, wider than the United States. Tithonium Chasma is almost 810 kilometers long (499 miles), 50 kilometers wide and over 6 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon

Investigating Mars: Ius Chasma

NASA Image and Video Library

2018-02-28

This VIS image shows the eastern end of Ius Chasma. The southern canyon wall is at the bottom of the image, with dark sand and sand dunes. The presence of mobile sand indicates that winds are eroding, depositing and changing the canyon floor. The rest of the image is dominated by large landslide deposits. At the top of the image are two overlapping deposits from landslides originating on the northern chasma wall. The landslide deposit on the left side of the image originate from the southern chasma wall. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earthquake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Ius Chasma is at the western end of Valles Marineris, south of Tithonium Chasma. Valles Marineris is over 4000 kilometers long, wider than the United States. Ius Chasma is almost 850 kilometers long (528 miles), 120 kilometers wide and over 8 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified

Investigating Mars: Melas Chasma

NASA Image and Video Library

2017-12-07

Melas Chasma is part of the largest canyon system on Mars, Valles Marineris. At only 563 km long (349 miles) it is not the longest canyon, but it is the widest. Located in the center of Valles Marineris, it has depths up to 9 km below the surrounding plains, and is the location of many large landslide deposits, as will as layered materials and sand dunes. There is evidence of both water and wind action as modes of formation for many of the interior deposits. This VIS image is located along the northern cliff face of the chasma. The linear features are large landslide surfaces. A region of sand dunes is located along the change in elevation from the cliff face at the top of the image and the floor of the canyon at the bottom of the image. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 31790 Latitude: -10.3951 Longitude: 290.141 Instrument: VIS Captured: 2009-02-12 20:47 https://photojournal.jpl.nasa.gov/catalog/PIA22137

Investigating Mars: Melas Chasma

NASA Image and Video Library

2017-12-06

Melas Chasma is part of the largest canyon system on Mars, Valles Marineris. At only 563 km long (349 miles) it is not the longest canyon, but it is the widest. Located in the center of Valles Marineris, it has depths up to 9 km below the surrounding plains, and is the location of many large landslide deposits, as will as layered materials and sand dunes. There is evidence of both water and wind action as modes of formation for many of the interior deposits. This VIS image is located right at the edge of the canyon with the surrounding plains - the flat area at the bottom of the image. Some small landslide deposits are visible originating at the cliff side. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 26762 Latitude: -13.4233 Longitude: 287.973 Instrument: VIS Captured: 2007-12-26 19:46 https://photojournal.jpl.nasa.gov/catalog/PIA22136

Investigating Mars: Melas Chasma

NASA Image and Video Library

2017-11-29

Melas Chasma is part of the largest canyon system on Mars, Valles Marineris. At only 563 km long (349 miles) it is not the longest canyon, but it is the widest. Located in the center of Valles Marineris, it has depths up to 9 km below the surrounding plains, and is the location of many large landslide deposits, as will as layered materials and sand dunes. There is evidence of both water and wind action as modes of formation for many of the interior deposits. This VIS image shows part of a large ridge of material near the south central part the canyon. The roughest looking material is the top of the ridge. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 16741 Latitude: -10.6629 Longitude: 285.637 Instrument: VIS Captured: 2005-09-22 17:54 https://photojournal.jpl.nasa.gov/catalog/PIA22130

Landslides in Valles Marineris, Mars

NASA Technical Reports Server (NTRS)

Lucchitta, B. K.

1979-01-01

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.

Investigating Mars: Ius Chasma

NASA Image and Video Library

2018-02-23

Continuing eastward thru central Ius Chasma, this image shows a section of chasma that is not dominated by landslide deposits. Geryon Montes, in the upper half of the image, has several visible faults, including a pair of faults that divide the uppermost ridge into two sections. Between the montes and the southern wall face is a region of sand and sand dunes. The presence of mobile sand indicates that winds are eroding, depositing and changing the canyon floor. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earthquake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Ius Chasma is at the western end of Valles Marineris, south of Tithonium Chasma. Valles Marineris is over 4000 kilometers long, wider than the United States. Ius Chasma is almost 850 kilometers long (528 miles), 120 kilometers wide and over 8 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and modifying

Investigating Mars: Ius Chasma

NASA Image and Video Library

2018-02-27

This VIS image shows part of the eastern end of Ius Chasma. Geryon Montes are located in the bottom half of the image. Between the montes and the southern wall face is a region of sand and sand dunes. The presence of mobile sand indicates that winds are eroding, depositing and changing the canyon floor. The top of the image is dominated by a large landslide deposit. The radial surface grooves are still visible, but the region as a whole as undergone significant erosion. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earthquake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Ius Chasma is at the western end of Valles Marineris, south of Tithonium Chasma. Valles Marineris is over 4000 kilometers long, wider than the United States. Ius Chasma is almost 850 kilometers long (528 miles), 120 kilometers wide and over 8 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling apart of the crust during the uplift of the vast Tharsis plateau. Landslides have enlarged the canyon walls and created deposits on the canyon floor. Weathering of the surface and influx of dust and sand have modified the canyon floor, both creating and

Bedrock and structural geologic maps of eastern Candor Sulci, western Ceti Mensa, and southeastern Ceti Mensa, Candor Chasma, Valles Marineris region of Mars

USGS Publications Warehouse

Okubo, Chris H.; Gaither, Tenielle A.

2017-05-12

This map product contains a set of three 1:18,000-scale maps showing the geology and structure of study areas in the western Candor Chasma region of Valles Marineris, Mars. These maps are part of an informal series of large-scale maps and map-based topical studies aimed at refining current understanding of the geologic history of western Candor Chasma. The map bases consist of digital elevation models and orthorectified images derived from High Resolution Imaging Science Experiment (HiRISE) data. These maps are accompanied by geologic cross sections, colorized elevation maps, and cutouts of HiRISE images showing key superposition relations. Also included in this product is a Correlation of Map Units that integrates units across all three map areas, as well as an integrated Description of Map Units and an integrated Explanation of Map Symbols. The maps were assembled using ArcGIS software produced by Environmental Systems Research Institute (http://www.esri.com). The ArcGIS projects and databases associated with each map are included online as supplemental data.

Investigating Mars: Ius Chasma

NASA Image and Video Library

2018-02-26

This VIS image shows part of eastern Ius Chasma. The lower elevations of Geryon Montes are located at the top of the image. Between the montes and the southern wall face is a region of sand and sand dunes. The presence of mobile sand indicates that winds are eroding, depositing and changing the canyon floor. The texture of the canyon floor beneath the dunes and elsewhere in the image is an indication of water, in some form, was part of the process creating the surface. There is a tongue of material emerging from the canyon wall that has steep sides, this may be a delta formed by material washing down the valley and into a body of standing water, like a lake. It may also just be a landslide deposit that has undergone extensive weathering. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earthquake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Ius Chasma is at the western end of Valles Marineris, south of Tithonium Chasma. Valles Marineris is over 4000 kilometers long, wider than the United States. Ius Chasma is almost 850 kilometers long (528 miles), 120 kilometers wide and over 8 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive

Investigating Mars: Tithonium Chasma

NASA Image and Video Library

2018-02-15

In this VIS image a complex region of multiple overlapping landslide deposits fills most the the frame. In the center of the image the top layer has the lobate edges and radial surface grooves of a low volume slide. It appears to be the top of a complex layering of materials, It is possible that all the lower layers are landslides as well. At the top of the image are a series of smaller lobate shaped landslide deposits Whether the layers formed very close in time of over thousands of years can not be determined in the image. Tithonium Chasma has numerous large landslide deposits. The resistant material of the plateau surface forms the linear ridges of the canyon wall. Large landslides have changed the walls and floor of the canyon. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Tithonium Chasma is at the western end of Valles Marineris. Valles Marineris is over 4000 kilometers long, wider than the United States. Tithonium Chasma is almost 810 kilometers long (499 miles), 50 kilometers wide and over 6 kilometers deep. In comparison, the Grand Canyon in Arizona is about 175 kilometers long, 30 kilometers wide, and only 2 kilometers deep. The canyons of Valles Marineris were formed by extensive fracturing and pulling

Deposition and deformation of stratified rocks in the northern Nia Mensa region of Valles Marineris, Mars

NASA Astrophysics Data System (ADS)

Okubo, C. H.

2016-12-01

Large-scale structural and geologic mapping based on HiRISE (High Resolution Imaging Science Experiment) digital elevation models reveals new details of the depositional environment for the stratified rocks in the northern Nia Mensa region of eastern Candor Chasma, Valles Marineris, Mars. The map area encompasses the contact between massive sedimentary rocks that comprise most of Nia Mensa and the stratified sedimentary and mass-wasting deposits exposed between Nia Mensa and the north wall of eastern Candor Chasma. The area contains a stratified fan-like deposit on the lower slopes of Nia Mensa. The strata within this deposit dip outward at < 10°, away from its morphologic apex, consistent with an origin as a depositional fan (rather than being carved into a fan shape by erosion). Whether this fan has a subaerial or submarine origin has not yet been determined. Additionally, the fan and surrounding stratified rocks exhibit evidence of soft-sediment deformation in the form of clastic dikes and contorted bedding, indicating that these deposits were water-saturated at the time of deformation. Finally, the northern section of the map area encompasses part of a fractured rise, and deposits interpreted as mud flows mantle the top of this rise. Inferred flow directions suggest that the mud erupted out of these fractures. These findings place constraints on the depositional environment of the local stratified bedrock. The presence of the fan deposit indicates that lateral transport was a component in the depositional history of these sediments. Therefore the sediments did not form entirely as a mantling deposit, such as air fall ash or sediments settled out of a water column. The soft-sediment deformation and subsurface mobilized sediments indicate that groundwater was present in the area after emplacement of the stratified deposits, but before its lithification. These findings point to a wet-playa to lacustrine depositional environment.

Investigating Mars: Melas Chasma

NASA Image and Video Library

2017-12-01

Melas Chasma is part of the largest canyon system on Mars, Valles Marineris. At only 563 km long (349 miles) it is not the longest canyon, but it is the widest. Located in the center of Valles Marineris, it has depths up to 9 km below the surrounding plains, and is the location of many large landslide deposits, as will as layered materials and sand dunes. There is evidence of both water and wind action as modes of formation for many of the interior deposits. Today's image covers part of the floor of the canyon. At the top of the image is one of the many hills found on the floor in this region. The linear grooved surface is part of a landslide deposit. Melas Chasma has many large landslide regions. Landslide deposits often have grooved surfaces with the grooves parallel to the direction of movement as the slide occurred. The ends of the landslide typically have a lobate edge, and will flow around large preexisting landforms. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 19112 Latitude: -11.1675 Longitude: 289.748 Instrument: VIS Captured: 2006-04-05 23:00 https://photojournal.jpl.nasa.gov/catalog/PIA22132

Investigating Mars: Candor Chasma

NASA Image and Video Library

2018-01-15

This THEMIS image shows part of western Candor Chasma. Near the bottom of the image is an impact crater. Impact craters are relatively rare within all the canyons of Valles Marineris. The lack of craters may be due to the relative young age of the canyon system - younger surfaces on Mars have fewer craters than older surfaces. Another factor is that the high rate of erosion and deposition within the canyon erodes the ejecta blanket and fills in the crater, effectively removing the crater over time. Candor Chasma is one of the largest canyons that make up Valles Marineris. It is approximately 810 km long (503 miles) and has is divided into two regions - eastern and western Candor. Candor is located south of Ophir Chasma and north of Melas Chasma. The border with Melas Chasma contains many large landslide deposits. The floor of Candor Chasma includes a variety of landforms, including layered deposits, dunes, landslide deposits and steep sided cliffs and mesas. Many forms of erosion have shaped Chandor Chasma. There is evidence of wind and water erosion, as well as significant gravity driven mass wasting (landslides). The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit

Mass wasting features in Juventae Chasma, Mars

NASA Astrophysics Data System (ADS)

Sarkar, Ranjan; Singh, Pragya; Porwal, Alok; Ganesh, Indujaa

2016-07-01

Introduction : We report mass-wasting features preserved as debris aprons from Juventae Chasma. Diverse lines of evidence and associated geomorphological features indicate that fluidized ice or water within the wall rocks of the chasma could be responsible for mobilizing the debris. Description : The distinctive features of the landslides in Juvenate Chasma are: (1) lack of a well-defined crown or a clear-cut section at their point of origin and instead the presence of amphitheatre-headed tributary canyons; (2) absence of slump blocks; (3) overlapping of debris aprons; (4) a variety of surface textures from fresh and grooved to degraded and chaotic; (5) rounded lobes of debris aprons; (6) large variation of sizes from small lumps (~0.52 m2) to large tongue shaped ones (~ 80 m2); (7) smaller average size of landslides as compared to other chasmas; and (8) occasional preservation of fresh surficial features indicating recent emplacement. Discussion : Amphitheatre-headed tributary canyons, which are formed due to ground water sapping, indicate that the same was responsible for wall-section collapse, although a structural control cannot be completely ruled out. The emplacement of the mass wasting features preferentially at the mouths of amphitheatre-headed tributary canyons along with the rounded flow fronts of the debris suggest fluids may have played a vital role in their emplacement. The mass-wasting features in Juventae Chasma are unique compared to other landslides in Valles Marineris despite commonalities such as the radial furrows, fan-shaped outlines, overlapping aprons and overtopped obstacles. The unique set of features and close association with amphitheatre-headed tributary canyons imply that the trigger of the landslides was not structural or tectonic but possibly weakness imparted by the presence of water or ice in the pore-spaces of the wall. Craters with fluidized ejecta blankets and scalloped depressions in the surrounding plateau also support this

Investigating Mars: Ius Chasma

NASA Image and Video Library

2018-02-22

Moving into the central part of Ius Chasma, the canyon profile changes. What started as a large graben south of the main chasma wall, has widened to create a central high ridge separating the chasm into two parallel sections. This interior ridge is called Geryon Montes. The northern canyon wall is at the top of the image, including several tongue shaped landslide deposits. The floor has been covered in deposits that may include landslide material and later materials such as air fall particles like dust and water lain layered deposits. The Geryon Montes are in the lower 1/3 of the image. Just to the top of the Montes are materials with different "colors". These are part of the layered materials inside the canyon. At the very bottom of the image a highly eroded landslide deposit exists. The materials on this side of Geryon Montes are at a higher elevation than the floor on the opposite side. The unusual texture of the canyon floor also points to layered materials that may have been laid down in standing water. A landslide is a failure of slope due to gravity. They initiate due to several reasons. A lower layer of poorly cemented/resistant material may have been eroded, undermining the wall above which then collapses; earth quake seismic waves can cause the slope to collapse; and even an impact event near the canyon wall can cause collapse. As millions of tons of material fall and slide down slope a scalloped cavity forms at the upper part where the slope failure occurred. At the material speeds downhill it will pick up more of the underlying slope, increasing the volume of material entrained into the landslide. Whereas some landslides spread across the canyon floor forming lobate deposits, very large volume slope failures will completely fill the canyon floor in a large complex region of chaotic blocks. Ius Chasma is at the western end of Valles Marineris, south of Tithonium Chasma. Valles Marineris is over 4000 kilometers long, wider than the United States. Ius

Investigating Mars: Melas Chasma

NASA Image and Video Library

2017-12-05

Melas Chasma is part of the largest canyon system on Mars, Valles Marineris. At only 563 km long (349 miles) it is not the longest canyon, but it is the widest. Located in the center of Valles Marineris, it has depths up to 9 km below the surrounding plains, and is the location of many large landslide deposits, as will as layered materials and sand dunes. There is evidence of both water and wind action as modes of formation for many of the interior deposits. Today's image is just a bit further to the west of yesterday's. Here there are no dunes, but extensive outcrops of layered material. It is possible that these layered deposits were formed by sediments settling in a lake. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 4335 Latitude: -10.3718 Longitude: 285.195 Instrument: VIS Captured: 2002-12-06 09:30 https://photojournal.jpl.nasa.gov/catalog/PIA22135

Investigating Mars: Melas Chasma

NASA Image and Video Library

2017-12-08

Melas Chasma is part of the largest canyon system on Mars, Valles Marineris. At only 563 km long (349 miles) it is not the longest canyon, but it is the widest. Located in the center of Valles Marineris, it has depths up to 9 km below the surrounding plains, and is the location of many large landslide deposits, as will as layered materials and sand dunes. There is evidence of both water and wind action as modes of formation for many of the interior deposits. This VIS image is located along the northern side of the chasma. The linear features are on the surface of a large landslide. This region of Melas Chasma is covered by several very large landslide deposits. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 36020 Latitude: -9.09641 Longitude: 288.172 Instrument: VIS Captured: 2010-01-27 03:51 https://photojournal.jpl.nasa.gov/catalog/PIA22138

Hematite-bearing materials surrounding Candor Mensa in Candor Chasma, Mars: Implications for hematite origin and post-emplacement modification

USGS Publications Warehouse

Fergason, Robin L.; Gaddis, Lisa R.; Rogers, A. D.

2014-01-01

The Valles Marineris canyon system on Mars is of enduring scientific interest in part due to the presence of interior mounds that contain extensive layering and water-altered minerals, such as crystalline gray hematite and hydrated sulfates. The presence of hematite and hydrated sulfate minerals is important because their host rock lithologies provide information about past environments that may have supported liquid water and may have been habitable. This work further defines the association and relationship between hematite-bearing materials and low albedo (presumably aeolian) deposits and layered materials, identifies physical characteristics that are strongly correlated with the presence of hematite, and refines hypotheses for the origin and post-emplacement modification (including transport) of these hematite-bearing and associated materials. There are only three regions surrounding Candor Mensa where hematite has been identified, even though morphologic properties are similar throughout the entire mensa. Three possible explanations for why hematite is only exposed in these regions include: (1) the topographic structure of the mensa walls concentrates hematite at the base of the layered deposits, influencing the ability to detect hematite from orbit; (2) the presence of differing amounts of “dark mantling material” and hematite-free erosional sediment; (3) the potential fracturing of the mensa and the influence of these structures on fluid flow and subsequent digenesis. The observations of hematite-bearing materials in this work support the hypothesis that hematite is eroding from a unit in the Candor Mensa interior layered deposits (ILD) and is being concentrated as a lag deposit adjacent to the lower layers of Candor Mensa and at the base in the form of dark aeolian material. Due to the similar geologic context associated with hematite-bearing and ILD materials throughout the Valles Marineris canyon system, the insight gained from studying these

Light-Toned Layers in Tithonium Chasma

NASA Image and Video Library

2015-08-12

Tithonium Chasma is a part of Valles Marineris, the largest canyon in the Solar System. If Valles Marineris was located on Earth, at more than 4,000 kilometers long and 200 kilometers wide, it would span across almost the entire United States. Tithonium Chasma is approximately 800 kilometers long. A "chasma," as defined by the International Astronomical Union, is an elongate, steep-sided depression. The walls of canyons often contain bedrock exposing numerous layers. In some regions, light-toned layered deposits erode faster than the darker-toned ones. The layered deposits in the canyons are of great interest to scientists, as these exposures may shed light on past water activity on Mars. The CRISM instrument on MRO indicates the presence of sulfates, hydrated sulfates, and iron oxides in Tithonium Chasma. Because sulfates generally form from water, the light-toned sulfate rich deposits in the canyons may contain traces of ancient life. The mid-section of this image is an excellent example of the numerous layered deposits, known as interior layered deposits. The exact nature of their formation is still unclear. However, some layered regions display parallelism between strata while other regions are more chaotic, possibly due to past tectonic activity. Lobe-shaped deposits are associated with depositional morphologies, considered indicative of possible periglacial activity. Overall, the morphological and lithological features we see today are the result of numerous geological processes, indicating that Mars experienced a diverse and more active geological past. http://photojournal.jpl.nasa.gov/catalog/PIA19868

Geomorphic clues to the Martian volatile inventory: Landslides

NASA Technical Reports Server (NTRS)

Pieri, D.; Kirkpatrick, A.

1984-01-01

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.

Global View of Mars Topography

NASA Technical Reports Server (NTRS)

2007-01-01

[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.

MEVTV Workshop on Tectonic Features on Mars

NASA Technical Reports Server (NTRS)

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

1989-01-01

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.

Variation of the 3-μm absorption feature on Mars: observations over eastern Valles Marineris by the mariner 6 infrared spectrometer

USGS Publications Warehouse

Calvin, Wendy M.

1997-01-01

A new approach for calibration of the shortest wavelength channel (1.8 to 6.0 μm) of the Mariner 6 infrared spectrometer was derived. This calibration provides a new description of the instrument response function from 1.8 to 3.7 μm and accounts for the thermal contribution to the signal at longer wavelengths. This allows the two segments from 1.8 to 6 μm to be merged into a single spectrum. The broad water of hydration absorption spans these two segments and is examined in these merged spectra using a method of band integration. Unlike previous analyses which rely on ratios at two wavelengths, the integration method can assess the band strength independently from the albedo in the near infrared. Spectra taken over the eastern end of the Valles Marineris are examined for variations of the band-integrated value, and three distinct clusters are found. Within the estimated uncertainty, two clusters (both low and high albedo) have approximately the same integrated band depth. The third cluster (medium albedo) has an integrated band depth about 10% higher. This difference cannot be systematically attributed to either surface or atmospheric parameters and suggests variation in the amount of water either chemically or physically bound in surface materials. Approximately one-half of the high integrated band depth cluster is associated with chaotic terrain at the source of outflow channels, the other half occurs over lower inertia plains adjacent to chasmata. This suggests both surface physical properties and mineralogy as well as water in exchange with the atmosphere contribute to the 3-μm bound water absorption.

A mineralized zone in Western Candor Chasma, Mars

NASA Technical Reports Server (NTRS)

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

1993-01-01

Spectral evidence from Viking and Phobos orbiting spacecraft suggests the local development of crystalline ferric oxides in a small region within Mars' equatorial Valles Marineris canyon system. This is the same area noted for its anomalous coloration in Viking Orbiter image 583 A by McEwen. The unique hue of the region in Viking color data is due to a reduced green filter reflectance, relative to violet and red, in comparison to surrounding materials of similar albedo or average reflectance. For this reason, the region does not appear spectrally distinctive in later Survey Mission images which were acquired without the green filter. In high resolution, the spectral unit can be seen to correspond to two 20 km long depressions on the margins of Candor Mensa, a heavily eroded plateau-forming deposit on the canyon floor. Laminae are conspicuous in several places on the plateau, particularly where 15 to 20 cycles of alternating bright and dark laminae are exposed at approximately 200 meter vertical intervals. Laminae are also visible on the steep, vertically fluted cliffs to the south of this depression. Concentric laminae indicate a basis in the depression on the southeastern margin of Candor Mensa at the location of the less pronounced hue anomaly. A distinct lineation at the base of the scarp at the western end of the canyon transects mottled canyon floor deposits believed to be among the youngest in the Valles marineris. Water is implicated in the formation of the iron oxides, since the steep surfaces of layered sediments elsewhere on Candor Mensa show no evidence of unusual coloration despite the fact that these materials were deposited concurrently with the strata exposed in the depressions. This suggests that the mineralization is secondary in nature and developed locally in association with the depressions, which could have ponded surface runoff or groundwater seepage.

Windblown Sand in Ganges Chasma

NASA Image and Video Library

2017-04-25

Dark, windblown sand covers intricate sedimentary rock layers in this image captured by NASA's Mars Reconnaissance Orbiter (MRO) from Ganges Chasma, a canyon in the Valles Marineris system. These features are at once familiar and unusual to those familiar with Earth's beaches and deserts. Most sand dunes on Earth are made of silica-rich sand, giving them a light color; these Martian dunes owe their dark color to the iron and magnesium-rich sand found in the region. https://photojournal.jpl.nasa.gov/catalog/PIA21600

Investigating Mars: Coprates Chasma

NASA Image and Video Library

2017-09-22

Coprates Chasma is one of the numerous canyons that make up Valles Marineris. The chasma stretches for 960 km (600 miles) from Melas Chasma to the west and Capri Chasma to the east. Landslide deposits, layered materials and sand dunes cover a large portion of the chasma floor. This image is located on the eastern side of Coprates Chasma, near Capri Chasma. The image shows multiple landslide features, which form lobed shaped deposits at the bottom of the canyon cliff face. Sand dunes are visible both on the landslide deposit and other parts of the canyon floor. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 16628 Latitude: -15.4094 Longitude: 304.726 Instrument: VIS Captured: 2005-09-13 10:38 https://photojournal.jpl.nasa.gov/catalog/PIA21990

Investigating Mars: Coprates Chasma

NASA Image and Video Library

2017-09-26

Coprates Chasma is one of the numerous canyons that make up Valles Marineris. The chasma stretches for 960 km (600 miles) from Melas Chasma to the west and Capri Chasma to the east. Landslide deposits, layered materials and sand dunes cover a large portion of the chasma floor. This image is located on the eastern side of Coprates Chasma, near Capri Chasma. The image shows multiple landslide features, which form lobed shaped deposits at the bottom of the canyon cliff face. Sand dunes are visible both on the landslide deposit and other parts of the canyon floor. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 16653 Latitude: -14.2759 Longitude: 303.707 Instrument: VIS Captured: 2005-09-15 12:01 https://photojournal.jpl.nasa.gov/catalog/PIA21991

Volcanism and Fluvio-Glacial Processes on the Interior Layered Deposits of Valles Marineris, Mars?

NASA Astrophysics Data System (ADS)

Chapman, M. G.

2005-12-01

The Interior Layered Deposits (ILDs) in Valles Marineris have been suggested to be possible sub-ice volcanoes. Recent images also show evidence of possible fluvio-glacial processes on the ILDs and hence volcano/ice/water interaction. For example, Mars Express Mission anaglyph from Orbit 334 of central Ophir and Candor Chasmata, THEMIS image V10551002, and MOC images E1700142 and E190020 show 2 ILD mounds in central Candor Chasma that have been sheared off at approximately equal elevations by some material that has been subsequently removed. Level shearing of ILD rock materials and subsequent removal of the abrasive material, suggest ice erosion and glacial processes because glacial ice is mobile enough to grind the rock and can melt away. Another adjacent ILD mound in Central Candor shows an abrupt flank termination and damming of material, rather than flank scour. The dammed material appears to be layers piled up in a ridge at the ILD base. This relation is observed on the HRSC anaglyph and MOC images E0101343 and E201146. Another ILD in Melas Chasma, seen on MOC image M0804981, shows lobes of flank material that terminate along a lineation; possibly suggesting lobe confinement against subsequently removed material. This morphology can also be observed on the flank of the Gangis Chasma ILD in MOC image M0705587. A possible terrestrial volcanic analog for this ILD flank morphology is the Helgafell hyaloclasitic ridge (tindar) in Iceland (Chapman et al., 2004), the eastern flank of which has a linear termination interpreted as largely unmodified and caused by hyalotuff material banked against a former ice wall that has since melted away (Schopka et al., 2003). Glacial shearing of some ILDs and confined banking of other ILDs suggest that these mounds formed at different times, as the sheared ILD likely predated ice and the confined ILD may have formed concurrently with ice. Alternatively, the banking may have been due to lack of shear forces (static ice) and confined

The central uplift of Elorza Crater: Insights into its geology and possible relationships to the Valles Marineris and Tharsis regions

NASA Astrophysics Data System (ADS)

Hopkins, R. T.; Tornabene, L. L.; Osinski, G. R.

2017-03-01

The majority of hydrated silicate occurrences on Mars are associated with impact craters (Ehlmann et al., 2011; Carter et al., 2013). Three formation mechanisms have been suggested to account for this correlation: (1) aqueous alteration occurred pre-impact, and was subsequently exposed via the impact (pre-impact; Bibring et al., 2006; Ehlmann et al., 2011), (2) heat generated from the impact facilitated the formation of a hydrothermal system, leading to alteration products (syn-impact; e.g. Marzo et al., 2010; Osinski et al., 2013), and/or (3) altered materials were deposited after crater formation, or formed within the crater well after the impact had taken place (post-impact). In this study, we analyze the central uplift of Elorza Crater, a ∼40 km diameter impact crater located ∼300 km north of Valles Marineris. To determine whether hydrated minerals found within the uplift were generated pre-, syn-, or post-impact, we used a data synthesis approach, utilizing High Resolution Imaging Science Experiment (HiRISE), Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), Context Camera (CTX), and Thermal Emission Imaging System (THEMIS) imagery. Opaline silica is observed in two locations on the southwestern side of the uplift and is interpreted to have been pre-existing or formed via hydrothermal alteration due to stratigraphic relationships with the overlying impact melt unit. Both Fe/Mg smectite and low-calcium pyroxene (LCP) are found throughout the uplift. Bedrock exposures on the northern wall of Coprates Chasma containing Fe/Mg smectite and LCP suggest an uplifted origin for these units. In all cases, although a pre-existing origin is probable, it is difficult to rule out the possibility of an impact-generated hydrothermal origin. Using the observed stratigraphy exposed in Coprates Chasma and bedrock exposures analyzed in nearby craters, we were able to constrain the pre-impact stratigraphy around Elorza. The near-subsurface consists of Hesperian

Potential 2001 Landing Sites in Melas Chasma, Mars

NASA Technical Reports Server (NTRS)

Weitz, C. M.; Lucchitta, B. K.; Chapman, M. G.

1999-01-01

We have selected four areas in Valles Marineris as potential landing sites for the 2001 mission. After 20 years of analyses, the formation of the Valles Marineris system of troughs and its associated deposits still has not been sufficiently explained. They could have formed by collapse, as tectonic grabens, or in two stages involving ancestral collapse basins later cut by grabens. Understanding all aspects of the Valles Marineris, in particular the interior layered deposits, would significantly contribute to deciphering the internal and external history of Mars. The deposits have been postulated to be remnants of wall rock, lacustrine deposits, mass wasting deposits, eolian deposits, carbonate deposits, or volcanic deposits. Because an understanding of the formation of Valles Marineris and its interior deposits is so important to deciphering the history of Mars, we have proposed landing sites for the 2001 mission on flat shelves of interior deposits in Melas Chasma.

Potential MER Landing Site in Melas Chasma

NASA Technical Reports Server (NTRS)

Weitz, C. M.; Parker, Timothy J.; Anderson, F. Scott

2001-01-01

We have selected one area in Valles Marineris as a potential landing site for the Mars Exploration Rover (MER) mission. After 30 years of analyses, the formation of the Valles Marineris system of troughs and its associated deposits still remains an enigma. Understanding all aspects of the Valles Marineris would significantly contribute to deciphering the internal and external history of Mars. A landing site within Melas Chasma could provide insight into both the formation of Valles Marineris and the composition and origin of the interior layered deposits (ILDs). The ILDs have been proposed as: (1) sedimentary deposits formed in lakes mass wasted material from the walls; (3) remnants of the wall rock; (4) carbonate deposits; (5) aeolian deposits; and (6) volcanic. More recently, Malin and Edgett suggest that the fine-scale, rhythmic layering seen in the interior deposits, as well as other layered deposits in craters, supports a sedimentary origin. Because an understanding of the formation of Valles Marineris and its interior deposits is so important to deciphering the history of Mars, we have proposed a landing site for the MER mission on an exposure of interior deposits in western Melas Chasma. Either MER-A and MER-B could land at this same location.

Investigating Mars: Coprates Chasma

NASA Image and Video Library

2017-10-06

Coprates Chasma is one of the numerous canyons that make up Valles Marineris. The chasma stretches for 960 km (600 miles) from Melas Chasma to the west and Capri Chasma to the east. Landslide deposits, layered materials and sand dunes cover a large portion of the chasma floor. This image is located in central Coprates Chasma. The brighter materials at the bottom of the image are layered deposits. It is unknown how deep these canyon deposits were when they formed. The layering is only visible due to erosion, making it difficult to estimate the original thickness. While layered deposits can be found on the floor of Coprates Chasma, they are most commonly found along the lower elevations and at the bottom of the cliff faces in the canyon. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 51810 Latitude: -12.6848 Longitude: 295.197 Instrument: VIS Captured: 2013-08-18 22:56 https://photojournal.jpl.nasa.gov/catalog/PIA22000

Investigating Mars: Coprates Chasma

NASA Image and Video Library

2017-09-27

Coprates Chasma is one of the numerous canyons that make up Valles Marineris. The chasma stretches for 960 km (600 miles) from Melas Chasma to the west and Capri Chasma to the east. Landslide deposits, layered materials and sand dunes cover a large portion of the chasma floor. This image is located in central Coprates Chasma. The image shows multiple landslide features, which form the bright lobed shaped deposits at the bottom of the canyon cliff face (top of image). The linear grooves on the top of the large landslide deposit were formed as the material came to rest on the canyon floor. The other features on the chasma floor are layered materials that have been weathered. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 16803 Latitude: -12.5614 Longitude: 296.887 Instrument: VIS Captured: 2005-09-27 20:25 https://photojournal.jpl.nasa.gov/catalog/PIA21992

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

NASA Astrophysics Data System (ADS)

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

2014-02-01

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

MOLA Global roughness map of Mars

NASA Technical Reports Server (NTRS)

2000-01-01

The median of slopes in 35-km windows indicate the typical roughness on 300-meter baselines. The rougher nature of the heavily cratered terrain in the Southern Hemisphere is apparent, as well as that of Valles Marineris (12S, 289E) canyon walls and the Olympus Mons (18N, 227E) aureole deposits. The Northern Lowlands are smooth, especially Amazonis Planitia (16N, 202E), a region to the west of Olympus Mons, were typical median slopes on these baselines are often smaller than 0.1 degree. A shaded relief map of the topography is overlaid is monochrome.

Vallis Marineris

NASA Image and Video Library

2009-09-18

This Mars Odyssey image transects Candor Chasma and Melas Chasma. Many canyon features are clearly visible in the image, including the steep cliff faces, landslides, and layered canyon floor deposits.

Morphology and geology of the ILD in Capri/Eos Chasma (Mars) from visible and infrared data

NASA Astrophysics Data System (ADS)

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

2010-05-01

Layered deposits have been observed in different locations at the surface of Mars, as crater floors and canyons systems. Their high interest relies in the fact they imply dynamical conditions in their deposition medium. Indeed, in opposition to most of the rocks of the martian surface, which have a volcanic origin, bright layered deposits seems to be sedimentary outcrops. Capri Chasma, a canyon located at the outlet of Valles Marineris, exhibits such deposits called Interior Layered Deposits (ILD). A large array of visible and infrared spacecraft data were used to build a Geographic Information System (GIS). We added HiRiSE images, from the recent MRO mission, which offer a spatial resolution of 25 cm per pixel. It allowed the mapping and the analysis of morphologies in the canyon. We highlighted that the ILD are several kilometers thick and flat-top stratified deposits. They overlap the chaotic floor. They are surrounded and cut by several flow features that imply that liquid water was still acting after the formation of these stratified deposits. The density of crater on the floor of Capri Chasma was quantified. The current topography was aged to 3 Gyr. All these morphological information allow us to suggest a plausible geological history for Capri Chasma. We propose that the Interior Layered Deposits have formed during the Hesperian, during or after the opening of the canyon. Some observations argue that water discharges have happened at several times before and just after the formation of the ILD. Liquid water must have played a major role in the formation of these deposits after 3.5 Gyr, implying that it was present in surface at least locally and temporarily. If this can be applied to ILD in others canyons of Valles Marineris, it would imply that liquid water was stable in surface or sub-surface during the Hesperian. Or in the actual conditions, with a cold and dry martian surface, long-term standing water bodies are not possible. Thus we suggest that either

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

USGS Publications Warehouse

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

2006-01-01

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

Investigating Mars: Coprates Chasma

NASA Image and Video Library

2017-09-29

Coprates Chasma is one of the numerous canyons that make up Valles Marineris. The chasma stretches for 960 km (600 miles) from Melas Chasma to the west and Capri Chasma to the east. Landslide deposits, layered materials and sand dunes cover a large portion of the chasma floor. This image is located in central Coprates Chasma. The floor of the chasma is covered by a complex deposit of material. This chaotic surface differs from most of the floor of the canyon and indicate a local process, perhaps a very large landslide or failure of the cliff face. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 27086 Latitude: -13.564 Longitude: 300.618 Instrument: VIS Captured: 2008-01-22 12:04 https://photojournal.jpl.nasa.gov/catalog/PIA21994

A Window into the Past

NASA Image and Video Library

2017-10-23

The layered sedimentary deposits inside the giant canyons of Mars have puzzled scientists for decades. These light toned deposits have fine, horizontal laminations that are unlike the rugged rim rock of the Valles Marineris as seen by NASA's Mars Reconnaisance Orbiter (MRO). Various ideas for the origin of the layered sediments have suggested lake deposits, wind blown dust and sand, or volcanic materials that erupted after the canyon was formed, and possibly filled with water. One particular layered deposit, called Ceti Mensa, attracted attention because its deep red color in images collected by the Viking Orbiter mission during the 1970s. Located in west Candor Chasma in the north of the Valles Marineris, Ceti Mensa is an undulating plateau that rises 3 kilometers above the canyon floor and is bounded by steep scarps up to 1.5 kilometers in height. Deep red hues are on the west-facing scarp in particular. The red tint may be due to the presence of crystalline ferric oxide, suggesting that the material may have been exposed to heat or water, or both. Spectral measurements by the Mars Express OMEGA and MRO CRISM instruments confirm the presence of hydrated sulfate salts, such as gypsum and kieserite . These minerals are important for two reasons. On Earth, they typically form in wet environments, suggesting that the deposits in Ceti Mensa may have formed under water. On Mars, these deposits could be valuable to future Martian colonists as fertilizer for growing crops. In a view of the colorful west-facing scarp of Ceti Mensa, we see the interior layers of the deposit, giving us a window into the past history of the sediments as they accumulated over time. We also see layers that were previously too small to view, and a surface that is thoroughly fractured, eroded into knobs, and partially covered by young dark sand dunes. https://photojournal.jpl.nasa.gov/catalog/PIA22051

Investigating Mars: Coprates Chasma

NASA Image and Video Library

2017-10-04

Coprates Chasma is one of the numerous canyons that make up Valles Marineris. The chasma stretches for 960 km (600 miles) from Melas Chasma to the west and Capri Chasma to the east. Landslide deposits, layered materials and sand dunes cover a large portion of the chasma floor. This image is located in eastern Coprates Chasma. The branching features near the bottom of the image are spurs of rock in the cliff face. The rock is more resistant to erosion that fine materials like sand and dust. Those materials are visible below the spurs, and then onto the canyon floor. Unlike the large landslide deposits, these small fans of material build up over time as the material above erodes. There are sand dunes along the edge of the fans in this image. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 36294 Latitude: -14.7055 Longitude: 303.066 Instrument: VIS Captured: 2010-02-18 17:20 https://photojournal.jpl.nasa.gov/catalog/PIA21998

Investigating Mars: Coprates Chasma

NASA Image and Video Library

2017-10-05

Coprates Chasma is one of the numerous canyons that make up Valles Marineris. The chasma stretches for 960 km (600 miles) from Melas Chasma to the west and Capri Chasma to the east. Landslide deposits, layered materials and sand dunes cover a large portion of the chasma floor. This image is located in eastern Coprates Chasma. The plateau above the chasma is visible in this image. The cliff face is very steep, with the elevation dropping over 3 miles from the plateau to the canyon floor. Craters are relatively rare on the chasma floor, the one in this image is fairly large. The crater rim has affected winds in this region, causing the interior dunes within the crater as well as the dunes outside the crater rim. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 37804 Latitude: -14.4843 Longitude: 302.193 Instrument: VIS Captured: 2010-06-23 01:14 https://photojournal.jpl.nasa.gov/catalog/PIA21999

Investigating Mars: Coprates Chasma

NASA Image and Video Library

2017-10-03

Coprates Chasma is one of the numerous canyons that make up Valles Marineris. The chasma stretches for 960 km (600 miles) from Melas Chasma to the west and Capri Chasma to the east. Landslide deposits, layered materials and sand dunes cover a large portion of the chasma floor. This image is located in central Coprates Chasma. In this image, there is a landslide deposit at the bottom of the image. The brighter material to the left of the landslide appears to be a rough surface likely etched by wind action. The chasma contains numerous regions of sand dunes, indicating that the wind plays a part in the erosion and deposition of fine materials in the canyon. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 35820 Latitude: -12.793 Longitude: 297.407 Instrument: VIS Captured: 2010-01-10 16:39 https://photojournal.jpl.nasa.gov/catalog/PIA21996

Investigating Mars: Coprates Chasma

NASA Image and Video Library

2017-09-28

Coprates Chasma is one of the numerous canyons that make up Valles Marineris. The chasma stretches for 960 km (600 miles) from Melas Chasma to the west and Capri Chasma to the east. Landslide deposits, layered materials and sand dunes cover a large portion of the chasma floor. This image is located in eastern Coprates Chasma. The image shows a relatively smooth floor, with a group of sand dune forms located against the wall of the chasma (bottom of image). The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 27061 Latitude: -13.9602 Longitude: 301.82 Instrument: VIS Captured: 2008-01-20 10:39 https://photojournal.jpl.nasa.gov/catalog/PIA21993

Investigating Mars: Candor Chasma

NASA Image and Video Library

2018-01-11

This image shows part of eastern Candor Chasma. At the top of the image is the steep cliff between the upper surface elevation and the depths of Candor Chasma. The bottom of the image is the cliff side of a large mesa. The two cliff faces have very different appearances. The cliff face between the top of the canyon and the bottom is likely layers of volcanic flows from the nearby Tharsis volcanoes. The mesa, however, is probably layers of sediments deposited in the canyon from wind, water and gravity driven erosion and deposition. These layered materials are much more easily eroded than the solid rock of the canyon sides. Candor Chasma is one of the largest canyons that make up Valles Marineris. It is approximately 810 km long (503 miles) and has is divided into two regions - eastern and western Candor. Candor is located south of Ophir Chasma and north of Melas Chasma. The border with Melas Chasma contains many large landslide deposits. The floor of Candor Chasma includes a variety of landforms, including layered deposits, dunes, landslide deposits and steep sided cliffs and mesas. Many forms of erosion have shaped Chandor Chasma. There is evidence of wind and water erosion, as well as significant gravity driven mass wasting (landslides). The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the

Investigating Mars: Candor Chasma

NASA Image and Video Library

2018-01-19

This image shows part of eastern Candor Chasma. At the top of the image is the steep cliff between the upper surface elevation and the depths of Candor Chasma. The bottom of the image is the cliff side of a large mesa. The two cliff faces have very different appearances. The cliff face between the top of the canyon and the bottom is likely layers of volcanic flows from the nearby Tharsis volcanoes. The mesa, however, is probably layers of sediments deposited in the canyon from wind, water and gravity driven erosion and deposition. These layered materials are much more easily eroded than the solid rock of the canyon sides. There is a landslide that originate from the northern cliff face and ran out into the canyon floor, visible as the lobate "tongue" at the right near the center of the image. Candor Chasma is one of the largest canyons that make up Valles Marineris. It is approximately 810 km long (503 miles) and has is divided into two regions - eastern and western Candor. Candor is located south of Ophir Chasma and north of Melas Chasma. The border with Melas Chasma contains many large landslide deposits. The floor of Candor Chasma includes a variety of landforms, including layered deposits, dunes, landslide deposits and steep sided cliffs and mesas. Many forms of erosion have shaped Chandor Chasma. There is evidence of wind and water erosion, as well as significant gravity driven mass wasting (landslides). The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north

Morphologic contrasts between Nirgal and Auqakuh Valles, Mars: Evidence of different crustal properties

NASA Technical Reports Server (NTRS)

Mackinnon, David J.; Tanaka, Kenneth L.; Winchell, Philip J.

1987-01-01

Photoclinometric measurements were made of sidewall slopes in Nirgal and Auqakuh Valles and these results were interpreted in terms of the geologic setting and a simple geomorphic model to provide insights into the physical properties of crustal materials in these areas. Nirgal was interpreted to be a runoff channel and Auqakuh to be a fretted channel. Geomorphologic arguments for the sapping origin of Nirgal and Auqakuh Valles were presented. The morphologies of the channels, however, differ greatly: the tributaries of Nirgal end abruptly in theater-headed canyons, whereas the heads of tributaries of Auqakuh shallow gradually. The plateau surface surrounding both channels appears to be covered by smooth materials, presumably lava flows; they are continuous and uneroded in the Nirgal area, but at Auqakuh they are largely eroded and several layers are exposed that total about 200 m in thickness. For Nirgal Valles, the measurements show that sidewalls in the ralatively shallow upper reaches of the channel have average slopes near 30 degrees and, in the lower reaches, sidewall slopes exceed 50 degrees. Auqakuh, on the other hand, has maximum sidewall slopes of 14 degrees and an approximate maximum depth of 1000 m. Faint, horizontal layering in portions of the lower reaches of Nirgal may indicate inhomogeneity in either composition or topography.

A Gem of a Find

NASA Technical Reports Server (NTRS)

2008-01-01

[figure removed for brevity, see original site] Click on image for larger annotated version

NASA's Mars Reconnaissance Orbiter has revealed Martian rocks containing a hydrated mineral similar to opal. The rocks are light-toned and appear cream-colored in this false-color image taken by the High Resolution Imaging Science Experiment (HiRISE) camera. Images acquired by the orbiter reveal that different layers of rock have different properties and chemistry. The opal minerals are located in distinct beds of rock outside of the large Valles Marineris canyon system and are also found in rocks within the canyon. The presence of opal in these relatively young rocks tells scientists that water, possibly as rivers and small ponds, interacted with the surface as recently as two billion years ago, one billion years later than scientists had expected. The discovery of this new category of minerals spread across large regions of Mars suggests that liquid water played an important role in shaping the planet's surface and possibly hosting life.

Landslides in Valles Marineris, Mars.

USGS Publications Warehouse

Lucchitta, B.K.

1979-01-01

Large landslides in the Martian equatorial troughs have been investigated with respect to morphology, geologic structure of the troughs, time of emplacement, similarity to terrestrial landslides, and origin and mechanism of transport. The morphologic variations of the landslides can be attributed mainly to their degree of confinement on trough floors. The huge size of many landslides is due to their occurrence on fault scarps that may have attained several kilometers in height in the absence of vigorous fluvial erosion on Mars. The mechanical efficiency of the Martian landslides is high but in accord with predictions from large landslides on earth. -from Author

Plains South of Valles Marineris

NASA Image and Video Library

2017-03-28

This enhanced-color sample reveals the incredible diversity of landforms on some Martian plains that appear bland and uniform at larger scales. Here we see layers, small channels suggesting water flow, craters, and indurated sand dunes. The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 25.7 centimeters (10.1 inches) per pixel (with 1 x 1 binning); objects on the order of 77 centimeters (30.3 inches) across are resolved.] North is up. http://photojournal.jpl.nasa.gov/catalog/PIA21573

Recent Volcanism in Valles Marineris

NASA Image and Video Library

2014-01-15

This image from NASA Mars Reconnaissance Orbiter shows cones with summit pits that are very similar to cinder cones on Earth. They are also very well-preserved, peppered by only small impact craters, so they must be geologically young.

Deposits along the Northern Wall of Melas Chasma

NASA Image and Video Library

2016-10-05

It has been known since the 1970s when the Viking orbiters took pictures of Mars that there are large (i.e., several kilometers-thick) mounds of light-toned deposits within the central portion of Valles Marineris. More recent higher resolution images of Mars, including this image of Melas Chasma, show that the wall rocks of Valles Mariners also contain similar, albeit thinner, light-toned deposits. Spectral data from the CRISM instrument indicate that the larger mounds are composed of sulfates. Some of the wall rock deposits are also made up of sulfates, but others contain clays or mixtures of several kinds of hydrated materials, suggesting that multiple aqueous processes, perhaps at different times within Valles Marineris, formed the variety of deposits we now observe. http://photojournal.jpl.nasa.gov/catalog/PIA21102

Chryse Basin channels: low-gradients and ponded flows.

USGS Publications Warehouse

Lucchitta, B.K.; Ferguson, H.M.

1983-01-01

Gradients on the floors of the Martian outflow channels that are derived from radar-elevation profiles across Lunae Planum and Chryse Basin have much lower values than those obtained from the U.S. Geological Survey's topographic map. Whereas the gradients of Maja and Ares Valles are similar to those of the catastrophic flood channels in the Scablands of Washington State, the gradients of Simud and Tiu Valles are essentially level, and the movement of fluids to the N poses problems. It is proposed that ponding may have formed lakes in depressions associated with the Valles Marineris grabens, ancient craters in the chaotic terrain area, and possibly even the regional low where most chaotic terrains occur. It is envisaged that lakes eventually overflowed, forming the present channels. When dams broke, floods were released catastrophically, with a final gigantic flood from the Valles Marineris system of troughs, which would have had sufficient head to move fluids across nearly level gradients through the Simud and Tiu channels. -P.Br.

Mars Stratigraphy Mission

NASA Technical Reports Server (NTRS)

Budney, C. J.; Miller, S. L.; Cutts, J. A.

2000-01-01

The Mars Stratigraphy Mission lands a rover on the surface of Mars which descends down a cliff in Valles Marineris to study the stratigraphy. The rover carries a unique complement of instruments to analyze and age-date materials encountered during descent past 2 km of strata. The science objective for the Mars Stratigraphy Mission is to identify the geologic history of the layered deposits in the Valles Marineris region of Mars. This includes constraining the time interval for formation of these deposits by measuring the ages of various layers and determining the origin of the deposits (volcanic or sedimentary) by measuring their composition and imaging their morphology.

Geologic Map of MTM -20012 and -25012 Quadrangles, Margaritifer Terra Region of Mars

USGS Publications Warehouse

Grant, J. A.; Wilson, S.A.; Fortezzo, C.M.; Clark, D.A.

2009-01-01

Mars Transverse Mercator (MTM) -20012 and -25012 quadrangles (lat 17.5 deg - 27.5 deg S., long 345 deg - 350 deg E.) cover a portion of Margaritifer Terra near the east end of Valles Marineris. The map area consists of a diverse assemblage of geologic surfaces including isolated knobs of rugged mountainous material, heavily cratered and dissected ancient highland material, a variety of plains materials, chaotic terrain materials, and one of the highest densities of preserved valleys and their associated deposits on the planet (Saunders, 1979; Baker, 1982; Phillips and others, 2000, 2001). The map area is centered on a degraded, partially filled, ~200-km-diameter impact structure (lat 22 deg S., long 347.5 deg E.), informally referred to as Parana basin, located between Parana Valles to the east and Loire Valles to the west. Parana Valles is a network of multidigitate, mostly east-west-oriented valleys that flowed west and discharged into Parana basin (Grant, 1987, 2000; Grant and Parker, 2002). Loire Valles, broadly comparable in length to the Grand Canyon on Earth, has a deeply incised channel within the map area that originates at the west-northwest edge of Erythraeum Chaos within Parana basin (Grant, 1987, 2000; Grant and Parker, 2002; Strom and others, 2000). Parana and Loire Valles, combined with Samara Valles to the west, form one of the most laterally extensive, well-integrated valley networks on Mars (Grant, 2000) and record a long history of modification by fluvial processes. The origin and morphology of the valley networks, therefore, provide insight into past environmental conditions, whereas their relation with other landforms helps constrain the timing and role of fluvial processes in the evolution and modification of the Margaritifer Terra region.

Alteration of the Crust Beneath a Highland Crater

NASA Technical Reports Server (NTRS)

2007-01-01

This image of the wall of Capri Chasma, in Valles Marineris, was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 1151 UTC (7:51 a.m. EDT) on October 6, 2007, near 12.03 degrees south latitude, 312.04 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, and is one of several dozen that CRISM has taken to search for exposed layering in the chasma walls.

Valles Marineris is a large canyon system that extends more than 4,000 kilometers (2,485 miles) covering nearly one-fifth of the planet's circumference. If it were located on Earth, Valles Marineris would stretch from the California coast to New England and hold a volume of water approximately equal to that held by the Mediterranean Sea. One of several chasmata that comprise Valles Marineris, Capri Chasma is located toward the eastern end of the larger system.

The upper left panel in the montage above reveals the location of the CRISM image on a mosaic taken by the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS). The CRISM data are centered on a resistant spur of material roughly 4 kilometers (2.5 miles) long, located below a crater whose floor was eroded away by the chasma's rim. The upper right panel reveals this spur in infrared false color. Bright streaks emanating downward from the ridge indicate mass wasting of the lighter material that caps the spur.

The lower two images are renderings of data draped over topography without vertical exaggeration. These images provide a view of the spur's elevation relative to the surrounding terrain - the lower right in infrared false color, the lower left in false color to reveal mineral content. The predominantly blue color of the lower left image shows that the chasma wall rock is rich in pyroxene, a major constituent of

The Antarctic dry valley lakes: Relevance to Mars

NASA Technical Reports Server (NTRS)

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

1989-01-01

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

Investigating Mars: Coprates Chasma

NASA Image and Video Library

2017-10-02

Coprates Chasma is one of the numerous canyons that make up Valles Marineris. The chasma stretches for 960 km (600 miles) from Melas Chasma to the west and Capri Chasma to the east. Landslide deposits, layered materials and sand dunes cover a large portion of the chasma floor. This image is located in eastern Coprates Chasma, just east of the previous image. In this image, the lobate margins of several landslide deposits are easy to identify. This indicates the chaotic surface in yesterday's image are materials emplaced by landslides. The brighter features at the bottom of the image are layered materials. There are also dunes in the region with the layered deposits. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 33037 Latitude: -13.8409 Longitude: 301.104 Instrument: VIS Captured: 2009-05-26 13:16 https://photojournal.jpl.nasa.gov/catalog/PIA21995

Layered Outcrops of Far West Candor Chasma

NASA Technical Reports Server (NTRS)

2000-01-01

[figure removed for brevity, see original site]

Images from Mariner 9 in 1972 revealed that some of the mesas and mounds found within the chasms of the martian 'Grand Canyon'--the Valles Marineris--have layers in them. Speculations as to the origin of these interior layered materials ranged from volcanic ash deposits to sediments laid down in lakes that could have partially filled the Vallis Marineris troughs, much as lakes now occupy portions of the rift valleys of eastern Africa. The proposal that the Valles Marineris once hosted deep martian lakes led to additional speculation as to the prospects for finding fossil evidence of martian life.

Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images have ten or more times better resolution than the Mariner 9 and Viking orbiter images taken in the 1970s. MOC images have indeed confirmed the presence of layered outcrops within the Valles Marineris. They have also shown places previously not suspected to have layered rock, and they have shown that these materials might not have formed in the Valles Marineris, but were instead deposited in craters that were subsequently buried long before the chasms opened up (see discussion below). The layered rock is now visible because of faulting and erosion.

The high resolution picture shown here (B, above right) was the first image received by MOC scientists that began to hint at a larger story of layered sedimentary rock on Mars. The picture shows a 1.5 km by 2.9 km (0.9 mi by 1.8 mi) area in far southwestern Candor Chasma (A, above left) that was--based on Mariner 9 and Viking orbiter images--not previously expected to exhibit layers. The MOC image reveals that the floor of western Candor Chasma at this location is indeed layered. What is most striking about the picture is the large number and uniformity of the layers, or beds. There are over 100 beds in this area, and each has about the same thickness (estimated to be about 10 meters (11 yards) thick). Each layer

Eos Chaos Rocks

NASA Technical Reports Server (NTRS)

2006-01-01

11 January 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered rock outcrops in Eos Chaos, located near the east end of the Valles Marineris trough system. The outcrops occur in the form of a distinct, circular butte (upper half of image) and a high slope (lower half of image). The rocks might be sedimentary rocks, similar to those found elsewhere exposed in the Valles Marineris system and the chaotic terrain to the east of the region.

Location near: 12.9oS, 49.5oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Summer

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

NASA Astrophysics Data System (ADS)

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

2009-04-01

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

Opaline silica in young deposits on Mars

USGS Publications Warehouse

Milliken, Ralph E.; Swayze, Gregg A.; Arvidson, Raymond E.; Bishop, Janice L; Clark, Roger N.; Ehlmann, Bethany L.; Green, Robert O.; Grotzinger, John P.; Morris, R.V.; Murchie, Scott L.; Mustard, John F.; Weitz, C.

2008-01-01

High spatial and spectral resolution reflectance data acquired by the Mars Reconnaissance Orbiter Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument reveal the presence of H2O- and SiOH-bearing phases on the Martian surface. The spectra are most consistent with opaline silica and glass altered to various degrees, confirming predictions based on geochemical experiments and models that amorphous silica should be a common weathering product of the basaltic Martian crust. These materials are associated with hydrated Fe sulfates, including H3O-bearing jarosite, and are found in finely stratified deposits exposed on the floor of and on the plains surrounding the Valles Marineris canyon system. Stratigraphic relationships place the formation age of these deposits in the late Hesperian or possibly the Amazonian, implying that aqueous alteration continued to be an important and regionally extensive process on Mars during that time.

Strike-slip faulting, wrinkle ridges, and time variable stress states in the Coprates Region of Mars

NASA Technical Reports Server (NTRS)

Schultz, Richard A.

1990-01-01

The existence of strike-slip faults was recently documented in two locations on Mars. Two clear examples are reviewed located southeast of Valles Marineris and preliminary evidence is presented for more widespread strike-slip deformation elsewhere in Coprates. The first two examples show that strike-slip faulting occurred in a broad zone east of the Coprates Rise spanning approximately 400 km east-west by perhaps 1000 km north-south. The last example suggests that the growth of major wrinkle ridges throughout Coprates may have been influenced by horizontally directed shear stresses and that more than one generation of ridges was produced. Thus, 'compressional' deformation of ridged plains south of Valles Marineris was spatially heterogeneous and a temporal change in stress may have been involved.

Coprates Chasma

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 21 June 2002) The Science This image covers a portion of Coprates Chasma, located near 15.5S, 57.8W, which is part of the Valles Marineris system of canyons that stretch for thousands of kilometers. This image displays clearly the contrast between bedrock, sand, and dust surfaces. The steepest slopes, such as on the canyon walls, appear to be free of the mantle of dust and sand that is nearly ubiquitous elsewhere in the image. Layering is clearly present in the bedrock unit, but it is not clear if that layering is due to sedimentary deposits or volcanic lava flows. Superimposed on the slopes is a mantle of dust in a manner that appears similar to snow covered mountains on Earth. This is because in both situations, fine-grained dry, particulate material is settling on a sloped surface. Collecting in the valleys and, in some cases, climbing up the slopes are several sand sheets. The amount of cover and the apparent thickness of these sands give some indication to the huge volume of material that is collected here. The orientation of the slip faces of the dunes in this image can be used to deduce the prevalent wind patterns in the region. In this case, the prevalent wind direction is towards the east but there are areas where the winds indicate a more complex system, perhaps indicating topographic control of the local winds. The Story The canyon walls of Coprates, the old name for the Persian River Ab-I-Diz, descend clearly at the top of this image, without being obscured by the dust that covers much of this region. Coprates Chasma is part of Valles Marineris, the largest canyon system in the solar system. In addition to the hard bedrock and dust, sand dunes also appear on the floor of the canyon. They almost look as though they've been raked by a Zen gardener, but the eastward-blowing wind is really responsible for their rows. Scientists can tell the direction of the wind by looking at the slip faces of the dunes -- that is, by identifying the steep

Hydrogeologic processes of large-scale tectonomagmatic complexes in Mongolia-southern Siberia and on Mars

USGS Publications Warehouse

Komatsu, G.; Dohm, J.M.; Hare, T.M.

2004-01-01

Large-scale tectonomagmatic complexes are common on Earth and Mars. Many of these complexes are created or at least influenced by mantle processes, including a wide array of plume types ranging from superplumes to mantle plumes. Among the most prominent complexes, the Mongolian plateau on Earth and the Tharsis bulge on Mars share remarkable similarities in terms of large domal uplifted areas, great rift canyon systems, and widespread volcanism on their surfaces. Water has also played an important role in the development of the two complexes. In general, atmospheric and surface water play a bigger role in the development of the present-day Mongolian plateau than for the Tharsis bulge, as evidenced by highly developed drainages and thick accumulation of sediments in the basins of the Baikal rift system. On the Tharsis bulge, however, water appears to have remained as ground ice except during periods of elevated magmatic activity. Glacial and periglacial processes are well documented for the Mongolian plateau and are also reported for parts of the Tharsis bulge. Ice-magma interactions, which are represented by the formation of subice volcanoes in parts of the Mongolian plateau region, have been reported for the Valles Marineris region of Mars. The complexes are also characterized by cataclysmic floods, but their triggering mechanism may differ: mainly ice-dam failures for the Mongolian plateau and outburst of groundwater for the Tharsis bulge, probably by magma-ice interactions, although ice-dam failures within the Valles Marineris region cannot be ruled out as a possible contributor. Comparative studies of the Mongolian plateau and Tharsis bulge provide excellent opportunities for understanding surface manifestations of plume-driven processes on terrestrial planets and how they interact with hydro-cryospheres. ?? 2004 Geological Society of America.

Investigating Mars: Candor Chasma

NASA Image and Video Library

2018-01-08

Candor Chasma is one of the largest canyons that make up Valles Marineris. It is approximately 810 km long (503 miles) and has is divided into two regions - eastern and western Candor. Candor is located south of Ophir Chasma and north of Melas Chasma. The border with Melas Chasma contains many large landslide deposits. The floor of Candor Chasma includes a variety of landforms, including layered deposits, dunes, landslide deposits and steep sided cliffs and mesas. Many forms of erosion have shaped Chandor Chasma. There is evidence of wind and water erosion, as well as significant gravity driven mass wasting (landslides). This image shows part of western Candor and the erosion of a large mesa. Layered materials are visible throughout the image and small dunes exist in several places. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 4360 Latitude: -6.08522 Longitude: 284.85 Instrument: VIS Captured: 2002-12-08 10:51 https://photojournal.jpl.nasa.gov/catalog/PIA22160

Investigating Mars: Candor Chasma

NASA Image and Video Library

2018-01-16

This VIS image shows part of the border between Chandor and Melas Chasmata. The entire image is landslide deposits. It is very common for landslides to develop linear surface grooves that parallel the direction of flow. Candor Chasma is one of the largest canyons that make up Valles Marineris. It is approximately 810 km long (503 miles) and has is divided into two regions - eastern and western Candor. Candor is located south of Ophir Chasma and north of Melas Chasma. The border with Melas Chasma contains many large landslide deposits. The floor of Candor Chasma includes a variety of landforms, including layered deposits, dunes, landslide deposits and steep sided cliffs and mesas. Many forms of erosion have shaped Chandor Chasma. There is evidence of wind and water erosion, as well as significant gravity driven mass wasting (landslides). The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 17003 Latitude: -8.20616 Longitude: 288.108 Instrument: VIS Captured: 2005-10-14 07:36 https://photojournal.jpl.nasa.gov/catalog/PIA22167

Melas Materials

NASA Image and Video Library

2006-05-01

This MOC image shows dark sand dunes superposed on layered, light-toned outcrops -- interpreted to be sedimentary rocks -- in Melas Chasma. Melas Chasma is part of the enormous Valles Marineris trough system

Layers and a Dust Devil in Melas Chasma

NASA Technical Reports Server (NTRS)

2000-01-01

One of the earliest observations made by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) was that the upper crust of the planet appears to be layered to considerable depth. This was especially apparent, early in the mission, in the walls of the Valles Marineris chasms. However, layered mesas and mounds within the Valles Marineris troughs were recognized all the way back in 1972 with Mariner 9 images. The MOC image presented here shows many tens of layers of several meters (yards) thickness in the walls of a mesa in southern Melas Chasma in Valles Marineris. Erosion by mass wasting--landslides--has exposed these layers and created the dark fan-shaped deposits seen near the middle of the image. The floor of Melas Chasma is dark and covered with many parallel ridges and grooves (lower 1/3 of image). In the lower left corner of the picture, a bright, circular dust devil can be seen casting a columnar shadow toward the left. This image, illuminated by sunlight from the right/lower right, covers an area 3 kilometers (1.9 miles) wide and 8.2 kilometers (5.1 miles) long. The scene is located near 10.1oS, 74.4oW and was acquired on July 11, 1999. North is toward the lower left.

Layers, Landslides, and Sand Dunes

NASA Technical Reports Server (NTRS)

2003-01-01

[figure removed for brevity, see original site]

Released 27 October 2003

This image shows the northern rim of one of the Valles Marineris canyons. Careful inspection shows many interesting features here. Note that the spurs and gullies in the canyon wall disappear some distance below the top of the canyon wall, indicating the presence of some smooth material here that weathers differently from the underlying rocks. On the floor of the canyon, there are remains from a landslide that came hurtling down the canyon wall between two spurs. Riding over the topography of the canyon floor are many large sand dunes, migrating generally from the lower right to upper left.

Image information: VIS instrument. Latitude -14.1, Longitude 306.7 East (53.3 West). 19 meter/pixel resolution.

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

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

Evoluton of the Tharsis Region of Mars

NASA Astrophysics Data System (ADS)

Anderson, R. C.; Dohm, J. M.; Maruyama, S.

2015-12-01

The evolution of the Tharsis region includes at least five major stages of Tharsis-related activity, which includes the formation of igneous plateaus, canyon and fault systems, volcanoes, and centers of magmatic-driven tectonism. This activity drove major environmental changes that were recorded in the walls of Valles Marineris, the circum-Chryse outflow channel system, the northern plains, and impact basins such as Argyre, among many other Martian features and landscapes. Environmental change included flooding and associated formation of lakes and oceans in basins such as the prominent northern plains and impact basins such as Argyre. This Tharsis-driven activity also included the formation of glaciers in the southern hemisphere and other landscape features (e.g., alluvial fans, periglacial landforms, gelifluction features including mass wasting, fluvial channels) indicative of an active landscape. At this conference, we will present the details of the evolution of Tharsis, as well as discuss contributing factors to its origin, estimated beginning development, and explanations for its longevity.

Melas Chasma

NASA Image and Video Library

2010-04-19

Melas Chasma is the central portion of Valles Marineris. This image taken by NASA 2001 Mars Odyssey shows a small portion of the floor of Melas Chasma, including layered deposits and wind eroded and deposited materials.

Ganges Quagmire

NASA Image and Video Library

2006-09-27

This MOC image shows dark-toned, windblown sands and ripples, surrounding a light-toned hill, interpreted to be sedimentary rock, in Ganges Chasma. Ganges Chasma is part of the giant Valles Marineris trough system on Mars

Ganges Chasma Landslide

NASA Image and Video Library

2002-05-21

This image from NASA Mars Odyssey spacecraft shows a spectacular landslide along a portion of the southern wall of Ganges Chasma within Valles Marineris. Landslides have very characteristic morphologies on Earth, which they also display on Mars.

Ganges Chasma

NASA Image and Video Library

2003-03-13

This false-color infrared image was taken by the camera system on the Mars Odyssey spacecraft over part of Ganges Chasma in Valles Marineris (approximately 13 degrees S, 318 degrees E). The infrared image has been draped over topography data obtained by Mars Global Surveyor. The color differences in this image show compositional variations in the rocks exposed in the wall and floor of Ganges (blue and purple) and in the dust and sand on the rim of the canyon (red and orange). The floor of Ganges is covered by rocks and sand composed of basaltic lava that are shown in blue. A layer that is rich in the mineral olivine can be seen as a band of purple in the walls on both sides of the canyon, and is exposed as an eroded layer surrounding a knob on the floor. Olivine is easily destroyed by liquid water, so its presence in these ancient rocks suggests that this region of Mars has been very dry for a very long time. The mosaic was constructed using infrared bands 5, 7, and 8, and covers an area approximately 150 kilometers (90 miles) on each side. This simulated view is toward the north. http://photojournal.jpl.nasa.gov/catalog/PIA04262

Kasei Valles

NASA Image and Video Library

2015-10-14

Kasei Valles is a valley system was likely carved by some combination of flowing water and lava. In some areas, erosion formed cliffs along the flow path resulting in water or lava falls. In some areas, erosion formed cliffs along the flow path resulting in water or lava falls. The flowing liquid is gone but the channels and "dry falls" remain. Since its formation, Kasei Valles has suffered impacts-resulting in craters-and has been mantled in dust, sand, and fine gravel as evidenced by the rippled textures. http://photojournal.jpl.nasa.gov/catalog/PIA20004

Mars Images MOC2-106 through 109

NASA Technical Reports Server (NTRS)

1999-01-01

Mars Global Surveyor images of the following are shown: Margin of lava flow in Daedalia Planum; Ripples in cratered terrain north of Hesperia Planum; Martian variety exhibited by the Olympica Fossae; and East Tithonium chasma wall, Valles Marineris.

Marte Valles site

NASA Technical Reports Server (NTRS)

Rice, Jim W.

1994-01-01

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.).

Ganges Chasma in 3-D

NASA Image and Video Library

1999-06-25

Ganges Chasma is part of the Valles Marineris trough system that stretches nearly 5,000 kilometers 3,000 miles across the western equatorial region of Mars. This stereo anaglyph is from NASA Mars Global Surveyor. 3D glasses are necessary.

Northwest Ius Chasma Landslide and Dune Field

NASA Image and Video Library

2013-07-10

Landslides in Valles Marineris are truly enormous, sometimes stretching from one wall to the base of another. This landslide, known as Ius Labes, would occupy the surface area of the state of Delaware, U.S., seen by NASA Mars Reconnaissance Orbiter.

Faulted Layers in Collapse Pits

NASA Image and Video Library

2016-04-06

This image shows a set of coalesced collapse pits in western Valles Marineris as seen by NASA Mars Reconnaissance Orbiter. Fine layers are exposed in the walls of the pits, and in some places those layers are displaced by faults.

4. DARK CANYON SIPHON VIEW ACROSS DARK CANYON AT ...

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

4. DARK CANYON SIPHON - VIEW ACROSS DARK CANYON AT LOCATION OF SIPHON. VIEW TO NORTHWEST - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

Monohydrated Sulfates in Aurorae Chaos

NASA Technical Reports Server (NTRS)

2008-01-01

This image of sulfate-containing deposits in Aurorae Chaos was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0653 UTC (2:53 a.m. EDT) on June 10, 2007, near 7.5 degrees south latitude, 327.25 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 40 meters (132 feet) across. The region covered is roughly 12 kilometers (7.5 miles) wide at its narrowest point.

Aurorae Chaos lies east of the Valles Marineris canyon system. Its western edge extends toward Capri and Eos Chasmata, while its eastern edge connects with Aureum Chaos. Some 750 kilometers (466 miles) wide, Aurorae Chaos is most likely the result of collapsed surface material that settled when subsurface ice or water was released.

The top panel in the montage above shows the location of the CRISM image on a mosaic taken by the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS). The CRISM data covers an area featuring several knobs of erosion-resistant material at one end of what appears to be a large teardrop shaped plateau. Similar plateaus occur throughout the interior of Valles Marineris, and they are formed of younger, typically layered rocks that post-date formation of the canyon system. Many of the deposits contain sulfate-rich layers, hinting at ancient saltwater.

The center left image, an infrared false color image, reveals a swath of light-colored material draped over the knobs. The center right image unveils the mineralogical composition of the area, with yellow representing monohydrated sulfates (sulfates with one water molecule incorporated into each molecule of the mineral).

The lower two images are renderings of data draped over topography with 5 times vertical exaggeration. These images provide a view of the topography and reveal how the monohydrated sulfate-containing deposits drape over the knobs and also an outcrop in lower-elevation parts of the

Layers and Fractures in Ophir Chasma

NASA Image and Video Library

2015-11-05

Ophir Chasma forms the northern portion of Valles Marineris, and this image from NASA Mars Reconnaissance Orbiter spacecraft features a small part of its wall and floor. The wall rock shows many sedimentary layers and the floor is covered with wind-blown ridges, which are intermediate in size between sand ripples and sand dunes. Rocks protruding on the floor could be volcanic intrusions of once-molten magma that have pushed aside the surrounding sedimentary layers and "froze" in place. Images like this can help geologists study the formation mechanisms of large tectonic systems like Valles Marineris. (The word "tectonics" does not mean the same thing as "plate tectonics." Tectonics simply refers to large stresses and strains in a planet's crust. Plate tectonics is the main type of tectonics that Earth has; Mars does not have plate tectonics.) http://photojournal.jpl.nasa.gov/catalog/PIA20044

Mineral resources of the Desolation Canyon, Turtle Canyon, and Floy Canyon Wilderness Study Areas, Carbon Emery, and Grand counties, Utah

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

Cashion, W.B.; Kilburn, J.E.; Barton, H.N.

1990-09-01

This paper reports on the Desolation Canyon, Turtle Canyon, and Floy Canyon Wilderness Study Areas which include 242,000 acres, 33,690 acres, and 23,140 acres. Coal deposits underlie all three study areas. Coal zones in the Blackhawk and Nelsen formations have identified bituminous coal resources of 22 million short tons in the Desolation Canyon Study Area, 6.3 million short tons in the Turtle Canyon Study Area, and 45 million short tons in the Floy Canyon Study Area. In-place inferred oil shale resources are estimated to contain 60 million barrels in the northern part of the Desolation Canyon area. Minor occurrences ofmore » uranium have been found in the southeastern part of the Desolation Canyon area and in the western part of the Floy Canyon area. Mineral resource potential for the study areas is estimated to be for coal, high for all areas, for oil and gas, high for the northern tract of the Desolation Canyon area and moderate for all other tracts, for bituminous sandstone, high for the northern part of the Desolation Canyon area, and low for all other tracts, for oil shale, low in all areas, for uranium, moderate for the Floy Canyon area and the southeastern part of the Desolation Canyon area and low for the remainder of the areas, for metals other than uranium, bentonite, zeolites, and geothermal energy, low in all areas, and for coal-bed methane unknown in all three areas.« less

Melas Chasm Enhanced Color

NASA Image and Video Library

1998-06-04

This picture centered at latitude 10 degrees S., longitude 74 degrees W. shows much of Mars Melas Chasm and a portion of Candor Chasm upper right in central Valles Marineris as seen by NASA's Viking Orbiter 2. http://photojournal.jpl.nasa.gov/catalog/PIA00156

Investigating Mars: Candor Chasma

NASA Image and Video Library

2018-01-10

This image shows part of eastern Candor Chasma. At the bottom of the image is the steep cliff between the upper surface elevation and the depths of Candor Chasma. The small lobate feature at the base of the cliff in the bottom of the image is a landslide deposit formed by failure of the cliff face and gravitational downslope movement of the material. Candor Chasma is one of the largest canyons that make up Valles Marineris. It is approximately 810 km long (503 miles) and has is divided into two regions - eastern and western Candor. Candor is located south of Ophir Chasma and north of Melas Chasma. The border with Melas Chasma contains many large landslide deposits. The floor of Candor Chasma includes a variety of landforms, including layered deposits, dunes, landslide deposits and steep sided cliffs and mesas. Many forms of erosion have shaped Chandor Chasma. There is evidence of wind and water erosion, as well as significant gravity driven mass wasting (landslides). The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 8916 Latitude: -7.95016 Longitude: 293.509 Instrument: VIS Captured: 2003-12-18 11:38 https://photojournal.jpl.nasa.gov/catalog/PIA22162

Investigating Mars: Candor Chasma

NASA Image and Video Library

2018-01-17

The bottom half of this image of central Candor Chasma shows a surface topography called chaos. Chaos is a region of small to medium sized mesas surrounded by valleys that are usually the same elevation. In this image sand and sand dunes are accumulating in the valleys and increasing in depth. Candor Chasma is one of the largest canyons that make up Valles Marineris. It is approximately 810 km long (503 miles) and has is divided into two regions - eastern and western Candor. Candor is located south of Ophir Chasma and north of Melas Chasma. The border with Melas Chasma contains many large landslide deposits. The floor of Candor Chasma includes a variety of landforms, including layered deposits, dunes, landslide deposits and steep sided cliffs and mesas. Many forms of erosion have shaped Chandor Chasma. There is evidence of wind and water erosion, as well as significant gravity driven mass wasting (landslides). The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 18251 Latitude: -6.45589 Longitude: 287.35 Instrument: VIS Captured: 2006-01-25 01:39 https://photojournal.jpl.nasa.gov/catalog/PIA22168

East Candor Chasma

NASA Technical Reports Server (NTRS)

1997-01-01

During its examination of Mars, the Viking 1 spacecraft returned images of Valles Marineris, a huge canyon system 5,000 km long, up to 240 km wide, and 6.5 km deep, whose connected chasma or valleys may have formed from a combination of erosional collapse and structural activity. The view shows east Candor Chasma, one of the connected valleys of Valles Marineris; north toward top of frame; for scale, the impact crater in upper right corner is 15 km (9 miles) wide. The image, centered at latitude 7.5 degrees S., longitude 67.5 degrees, is a composite of Viking 1 Orbiter high-resolution (about 80 m/pixel or picture element) images in black and white and low-resolution (about 250 m/pixel) images in color. The Viking 1 craft landed on Mars in July of 1976.

East Candor Chasma occupies the eastern part of the large west-northwest-trending trough of Candor Chasma. This section is about 150 km wide. East Candor Chasma is bordered on the north and south by walled cliffs, most likely faults. The walls may have been dissected by landslides forming reentrants; one area on the north wall shows what appears to be landslide debris. Both walls show spur-and-gully morphology and smooth sections. In the lower part of the image northwest-trending, linear depressions on the plateau are younger graben or fault valleys that cut the south wall.

Material central to the chasma shows layering in places and has been locally eroded by the wind to form flutes and ridges. These interior layered deposits have curvilinear reentrants carved into them, and in one locale a lobe flows away from the top of the interior deposit. The lobe may be mass-wasting deposits due to collapse of older interior deposits (Lucchitta, 1996, LPSC XXVII abs., p. 779- 780); this controversial idea requires that the older layered deposits were saturated with ice, perhaps from former lakes, and that young volcanism and/or tectonism melted the ice and made the material flow.

Investigating Mars: Candor Chasma

NASA Image and Video Library

2018-01-09

This image shows part of western Candor and the erosion of a large mesa. Layered materials are visible throughout the image. The dark material with the linear appearance in the middle of the image are sand dunes. Sand dunes are created by wind action. At the present time, wind is the active process shaping the surface. Candor Chasma is one of the largest canyons that make up Valles Marineris. It is approximately 810 km long (503 miles) and has is divided into two regions - eastern and western Candor. Candor is located south of Ophir Chasma and north of Melas Chasma. The border with Melas Chasma contains many large landslide deposits. The floor of Candor Chasma includes a variety of landforms, including layered deposits, dunes, landslide deposits and steep sided cliffs and mesas. Many forms of erosion have shaped Chandor Chasma. There is evidence of wind and water erosion, as well as significant gravity driven mass wasting (landslides). The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 6245 Latitude: -5.77639 Longitude: 284.339 Instrument: VIS Captured: 2003-05-12 14:49 https://photojournal.jpl.nasa.gov/catalog/PIA22161

Investigating Mars: Candor Chasma

NASA Image and Video Library

2018-01-18

This image of central Candor Chasma shows a surface topography called chaos. Chaos is a region of small to medium sized mesas surrounded by valleys that are usually the same elevation. In this image sand and sand dunes have accumulated in the valleys near the top of the image, but are not as prevalent towards the bottom of the image. Candor Chasma is one of the largest canyons that make up Valles Marineris. It is approximately 810 km long (503 miles) and has is divided into two regions - eastern and western Candor. Candor is located south of Ophir Chasma and north of Melas Chasma. The border with Melas Chasma contains many large landslide deposits. The floor of Candor Chasma includes a variety of landforms, including layered deposits, dunes, landslide deposits and steep sided cliffs and mesas. Many forms of erosion have shaped Chandor Chasma. There is evidence of wind and water erosion, as well as significant gravity driven mass wasting (landslides). The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 26213 Latitude: -7.25478 Longitude: 287.032 Instrument: VIS Captured: 2007-11-11 14:48 https://photojournal.jpl.nasa.gov/catalog/PIA22169

Maja Valles

NASA Image and Video Library

2012-07-19

The streamlined island in this image from NASA 2001 Mars Odyssey spacecraft formed within the channel of Maja Valles. The flow of water was deflected by the crater leaving material in the lee of the crater.

Osuga Valles

NASA Image and Video Library

2018-04-18

Osuga Valles is a complex set of channels located near Eos Chasma. Orbit Number: 71243 Latitude: -15.2123 Longitude: 321.617 Instrument: VIS Captured: 2018-01-05 06:57 https://photojournal.jpl.nasa.gov/catalog/PIA22372

Mixtures of Sulfates in Melas Chasma

NASA Image and Video Library

2017-09-04

In this image from NASA's Mars Reconnaissance Orbiter, layering within the light-toned sulfate deposit is the result of different states of hydration. Some of the layers have sulfates with little water (known as monohydrated sulfates) whereas other layers have higher amounts of water (called polyhydrated sulfates). The different amounts of water within the sulfates may reflect changes in the water chemistry during deposition of the sulfates, or may have occurred after the sulfates were laid down when heat or pressure forced the water out of some layers, causing a decrease in the hydration state. Many locations on Mars have sulfates, which are sedimentary rocks formed in water. Within Valles Marineris, the large canyon system that cuts across the planet, there are big and thick sequences of sulfates. The CRISM instrument on MRO is crucial for telling scientists which type of sulfate is associated with each layer, because each hydration state will produce a spectrum with absorptions at specific wavelengths depending upon the amount of water contained within the sulfate. https://photojournal.jpl.nasa.gov/catalog/PIA21935

Tiu Valles

NASA Image and Video Library

2002-11-26

The ancient, catastrophic floods on Mars, whose origins remain a mystery, produced a channeled and scoured landscape like this one, which is called Tiu Valles and was imaged by NASA Mars Odyssey spacecraft. http://photojournal.jpl.nasa.gov/catalog/PIA04013

Auqakuh Valles

NASA Image and Video Library

2002-06-17

The ancient sinuous river channel shown in this image by NASA Mars Odyssey spacecraft 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.

Colorful Bedrock Exposed in a Landslide Scarp

NASA Image and Video Library

2016-12-07

The steep walls of Valles Marineris sometimes fail, creating giant landslides. This provides a clean exposure of the underlying bedrock. This image of the north wall of Ganges Chasma reveals bedrock with diverse colors and textures, representing different geologic units. http://photojournal.jpl.nasa.gov/catalog/PIA21217

Investigating Mars: Candor Chasma

NASA Image and Video Library

2018-01-12

This image shows part of eastern Candor Chasma. In the middle of the image is a set of linear ridges and valleys. These features are called yardangs and are created by uniform winds that winnow away materials. Once the valleys are formed the wind then is funneled through the valley and erosion continues more in the valley than on the ridges. At the bottom of the valleys there are sand materials covering the slope between the valleys and the surrounding chasma floor. Beyond this coating of sand there are darker sand deposits where wind has accumulated the sand into larger dunes. The brighter mesa on the right side of the image has also been wind eroded into yardangs, but are aligned in a different direction than the larger yardangs. This indicates that wind directions within the canyon have changed over time. Candor Chasma is one of the largest canyons that make up Valles Marineris. It is approximately 810 km long (503 miles) and has is divided into two regions - eastern and western Candor. Candor is located south of Ophir Chasma and north of Melas Chasma. The border with Melas Chasma contains many large landslide deposits. The floor of Candor Chasma includes a variety of landforms, including layered deposits, dunes, landslide deposits and steep sided cliffs and mesas. Many forms of erosion have shaped Chandor Chasma. There is evidence of wind and water erosion, as well as significant gravity driven mass wasting (landslides). The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that

Basaltic Martian analogues from the Baikal Rift Zone and Mongolian terranes

NASA Astrophysics Data System (ADS)

Gurgurewicz, J.; Kostylew, J.

2007-08-01

In order to compare the results of studies of the western part of the Valles Marineris canyon on Mars there have been done field works on terrestrial surface areas similar with regard to geological setting and environmental conditions. One of the possible terrestrial analogues of the Valles Marineris canyon is the Baikal Rift Zone [1]. Field investigations have been done on the south end of the Baikal Lake, in the Khamar-Daban massif, where the outcrops of volcanic rocks occur. The second part of the field works has been done in the Mongolian terranes: Mandalovoo, Gobi Altay and Bayanhongor, because of environmental conditions being similar to those on Mars. The Mandalovoo terrane comprises a nearly continuous Paleozoic islandarc sequence [2]. In the Gobi Altay terrane an older sequence is capped by younger Devonian-Triassic volcanic-sedimentary deposits [2]. The Bayanhongor terrane forms a northwest-trending, discontinuous, narrow belt that consists of a large ophiolite allochton [3]. The collected samples of basalts derive from various geologic environments. The CORONA satellite-images have been used for the imaging of the Khamar-Daban massif and the Mandalovoo terrane. These images have the same spatial resolution and range as the Mars Orbiter Camera images of the Mars Global Surveyor mission. In the Mandalovoo terrane these images allowed to find an area with large amounts of tectonic structures, mainly faults (part of the Ongi massif), similar to the studied area on Mars. Microscopic observations in thin sections show diversification of composition and structures of basalts. These rocks have mostly a porphyric structure, rarely aphyric. The main components are plagioclases, pyroxenes and olivines phenocrysts, in different proportions. The groundmass usually consist of plagioclases, pyroxenes and opaques. The most diversified are basalts from the Mandalovoo terrane. Infrared spectroscopy has been used to analyse the composition of the rock material and compare

Kasei Valles Fractures

NASA Image and Video Library

2010-10-27

The fracture system shown in this image from NASA Mars Odyssey is on the northern margin of the Kasei Valles lowland. Fractures like this can become chaos with continued downdropping of blocks and widening fractures.

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

USGS Publications Warehouse

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

1990-01-01

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

77 FR 67673 - Fernando Valle, M.D.; Decision and Order

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-13

... DEPARTMENT OF JUSTICE Drug Enforcement Administration [Docket No. 12-56] Fernando Valle, M.D... Certificate of Registration Numbers FV1935595, FV2000711, and FV2000735, issued to Fernando Valle, M.D., be, and they hereby are, revoked. I further order that any pending applications of Fernando Valle, M.D...

Primary centers and secondary concentrations of tectonic activity through time in the western hemisphere of Mars

USGS Publications Warehouse

Anderson, R.C.; Dohm, J.M.; Golombek, M.P.; Haldemann, A.F.C.; Franklin, B.J.; Tanaka, K.L.; Lias, J.; Peer, B.

2001-01-01

Five main stages of radial and concentric structures formed around Tharsis from the Noachian through the Amazonian as determined by geologic mapping of 24,452 structures within the stratigraphic framework of Mars and by testing their radial and concentric orientations. Tectonic activity peaked in the Noachian (stage 1) around the largest center, Claritas, an elongate center extending more than 20?? in latitude and defined by about half of the total grabens which are concentrated in the Syria Planum, Thaumasia, and Tempe Terra regions. During the Late Noachian and Early Hesperian (stage 2), extensional structures formed along the length of present-day Valles Marineris and in Thaumasia (with a secondary concentration near Warrego Vallis) radial to a region just to the south of the central margin of Valles Marineris. Early Hesperian (stage 3) radial grabens in Pavonis, Syria, Ulysses, and Tempe Terra and somewhat concentric wrinkle ridges in Lunae and Solis Plana and in Thaumasia, Sirenum, Memnonia, and Amazonis are centered northwest of Syria with secondary centers at Thaumasia, Tempe Terra, Ulysses Fossae, and western Valles Marineris. Late Hesperian/Early Amazonian (stage 4) structures around Alba Patera, the northeast trending alignment of Tharsis Montes, and Olympus Mons appears centered on Alba Patera. Stage 5 structures (Middle-Late Amazonian) represent the last pulse of Tharsis-related activity and are found around the large shield volcanoes and are centered near Pavonis Mons. Tectonic activity around Tharsis began in the Noachian and generally decreased through geologic time to the Amazonian. Statistically significant radial distributions of structures formed during each stage, centered at different locations within the higher elevations of Tharsis. Secondary centers of radial structures during many of the stages appear related to previously identified local magmatic centers that formed at different times and locations throughout Tharsis. Copyright 2001 by

The Plains are Not Plain

NASA Image and Video Library

2016-06-01

This image from NASA Mars Reconnaissance Orbiter spacecraft covers some of the plains south of Capri Chasma in eastern Valles Marineris. Where the aeolian (wind-blown) sedimentary cover has been stripped away, we see diverse colors indicative of of a variety of altered minerals formed in Mars' wetter past. http://photojournal.jpl.nasa.gov/catalog/PIA20730

AmeriFlux US-Vcp Valles Caldera Ponderosa Pine

DOE Data Explorer

Litvak, Marcy [University of New Mexico

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-Vcp Valles Caldera Ponderosa Pine. Site Description - The Valles Caldera Ponderosa Pine site is located in the 1200km2 Jemez River basin of the Jemez Mountains in north-central New Mexico at the southern margin of the Rocky Mountain ecoregion. The Ponderosa Pine forest is the warmest and lowest (below 2700m) zone of the forests in the Valles Caldera National Preserve. Its vegetation is composed of a Ponderosa Pine (Pinus Ponderosa) overstory and a Gambel Oak (Quercus gambelii) understory.

Stratigraphy of the Kasei Valles region, Mars

NASA Technical Reports Server (NTRS)

Robinson, Mark S.; Tanaka, Kenneth L.

1987-01-01

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.

Marte Valles Crater 'Island'

NASA Technical Reports Server (NTRS)

2004-01-01

10 April 2004 Marte Valles is an outflow channel system that straddles 180oW longitude between the region south of Cerberus and far northwestern Amazonis. The floor of the Marte valleys have enigmatic platy flow features that some argue are formed by lava, others suggest they are remnants of mud flows. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an island created in the middle of the main Marte Valles channel as fluid---whether lava or mud---flowed past two older meteor impact craters. The craters are located near 21.5oN, 175.3oW. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

Geomorphic process fingerprints in submarine canyons

USGS Publications Warehouse

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

2013-01-01

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

24. VIEW OF CANYON TAKEN FROM NORTH CANYON RIM AROUND ...

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

24. VIEW OF CANYON TAKEN FROM NORTH CANYON RIM AROUND 1920. CAMERA FACES SOUTH. VILLAGE IS TREE-COVERED AREA TO LEFT OF DAM AND POWERHOUSE. SUPERINTENDENT SAM GLASS'S ORCHARD IS DOWNSTREAM OF DAM ABOUT A QUARTER OF A MILE. - Swan Falls Village, Snake River, Kuna, Ada County, ID

East Candor Chasma

NASA Image and Video Library

1998-06-08

During its examination of Mars, NASA's Viking 1 spacecraft returned images of Valles Marineris, a huge canyon system 5,000 km long, up to 240 km wide, and 6.5 km deep, whose connected chasma or valleys may have formed from a combination of erosional collapse and structural activity. The view shows east Candor Chasma, one of the connected valleys of Valles Marineris; north toward top of frame; for scale, the impact crater in upper right corner is 15 km (9 miles) wide. The image, centered at latitude 7.5 degrees S., longitude 67.5 degrees, is a composite of Viking 1 Orbiter high-resolution (about 80 m/pixel or picture element) images in black and white and low-resolution (about 250 m/pixel) images in color. The Viking 1 craft landed on Mars in July of 1976. East Candor Chasma occupies the eastern part of the large west-northwest-trending trough of Candor Chasma. This section is about 150 km wide. East Candor Chasma is bordered on the north and south by walled cliffs, most likely faults. The walls may have been dissected by landslides forming reentrants; one area on the north wall shows what appears to be landslide debris. Both walls show spur-and-gully morphology and smooth sections. In the lower part of the image northwest-trending, linear depressions on the plateau are younger graben or fault valleys that cut the south wall. Material central to the chasma shows layering in places and has been locally eroded by the wind to form flutes and ridges. These interior layered deposits have curvilinear reentrants carved into them, and in one locale a lobe flows away from the top of the interior deposit. The lobe may be mass-wasting deposits due to collapse of older interior deposits (Lucchitta, 1996, LPSC XXVII abs., p. 779- 780); this controversial idea requires that the older layered deposits were saturated with ice, perhaps from former lakes, and that young volcanism and/or tectonism melted the ice and made the material flow. http

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Carbon transport in Monterey Submarine Canyon

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Granicus Valles - False Color

NASA Image and Video Library

2015-01-12

The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of Granicus Valles.

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

NASA Astrophysics Data System (ADS)

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

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

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

NASA Astrophysics Data System (ADS)

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

2016-02-01

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

Formative flow in bedrock canyons

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

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

ERIC Educational Resources Information Center

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

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

Grand Canyon Monitoring and Research Center

USGS Publications Warehouse

Hamill, John F.

2009-01-01

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

Athabasca Valles, Mars: a lava-draped channel system.

PubMed

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

2007-09-21

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.

Wintertime Boundary Layer Structure in the Grand Canyon.

NASA Astrophysics Data System (ADS)

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

1999-08-01

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

Dunes in Nectaris Montes

NASA Image and Video Library

2018-05-14

This image from NASA's Mars Reconnaissance Orbiter (MRO) shows some of these on the slopes of Nectaris Montes within Coprates Chasma. Sand dunes in Valles Marineris can be impressive in size, with steep slopes that seem to climb and descend. The brighter bedforms are inactive while the bigger dunes move over the landscape, burying and exhuming the surface. https://photojournal.jpl.nasa.gov/catalog/PIA22455

Origin of Martian Interior Layered Deposits (ILDs) by atmospherically driven processes

NASA Astrophysics Data System (ADS)

Michalski, J. R.; Niles, P. B.

2011-12-01

Since the first photogeologic exploration of Mars, vast mounds of layered sediments found within the Valles Marineris canyon system (Interior Layered Deposits or ILDs) have remained unexplained. Recent spectroscopic results showing that these materials contain coarse-grained hematite [1] and sulfate [2-8] suggest that they are fundamentally similar to layered sulfate deposits seen elsewhere on Mars [3], and are therefore a key piece of Mars' global aqueous history. Layered sulfate deposits (including ILDs) are often considered to have formed in association with transient, wet surface environments caused by groundwater upwelling [9] in the Hesperian. Here, we use spectroscopic mapping along with geomorphic observations and mass balance calculations to demonstrate that the sulfate-bearing ILDs likely did not form due to groundwater upwelling or any similar playa-lacustrine scenario. Instead, the ILDs likely formed from atmospherically driven processes in a configuration similar to that observed today. We suggest that Hesperian layered sulfate deposits formed in response to massive amounts of pyroclastic volcanism and SO2-outgassing that peaked near 3.5-3.7 Ga in a Martian climate that was largely cold and dry. This origin for the ILDs is also applicable to other layered terrain of similar age and characteristics, including sulphate-bearing crater fill, chaos terrains, and the Meridiani Planum sediments. [1] Weitz, C. M., Lane, M. D., Staid, M. & Dobrea, E. N. Gray hematite distribution and formation in Ophir and Candor chasmata. Journal of Geophysical Research-Planets 113, doi:E02016 10.1029/2007je002930 (2008). [2] Wendt, L. et al. Sulfates and iron oxides in Ophir Chasma, Mars, based on OMEGA and CRISM observations. Icarus 213, 86-103, doi:10.1016/j.icarus.2011.02.013 (2011). [3] Murchie, S. et al. Evidence for the origin of layered deposits in Candor Chasma, Mars, from mineral composition and hydrologic modeling. Journal of Geophysical Research-Planets 114, doi

Flooded Place

NASA Image and Video Library

2006-07-26

This MOC image shows gullies a portion of a flood-carved canyon within the larger Kasei Valles system on Mars. This canyon is the result of the very last flood event that poured through the Kasei valleys, long ago

78 FR 48670 - Boulder Canyon Project

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-09

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

Chapter 1. Valles Caldera National Preserve land use history

Treesearch

Kurt F. Anschuetz

2007-01-01

The land use history of the Valles Caldera National Preserve (VCNP) extends back over thousands of years. Few known archaeological properties in the Valles Caldera date to the Paleoindian period (10000/9500–5500 B.C.). These finds include the recent discovery, during ongoing archaeological studies (Dr. Bob Parmeter, personal communication, VCNP, Los Alamos, 2005), of...

Street canyon aerosol pollutant transport measurements.

PubMed

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

2004-12-01

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

Auqakuh Valles

NASA Technical Reports Server (NTRS)

2002-01-01

(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

77 FR 48151 - Boulder Canyon Project

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-13

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

Durable terrestrial bedrock predicts submarine canyon formation

USGS Publications Warehouse

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

2017-01-01

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

Layered Deposits on the floor of Ganges Chasma

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 29 March 2002) The Science The Story These layered deposits are located on the floor of a large canyon called Ganges Chasma which is a part of the Valles Marineris. Dramatic layering can be seen throughout the deposit. Different styles of erosion are manifest in these different layers and at different locations within the layered material. For example, the southern portion of these deposits have a pronounced fluting, whereas in other areas the same layers are more intact. Relatively dark dunes and sand sheets can be observed surrounding the relatively brighter layered material in the upper right and lower portions of the image. Darker material also appears to mantle select areas of the layered deposits. The formation of the dunes is influenced by topography; this influence is best illustrated in the upper left of the image where a small hillock has interfered with the local wind flow. Impact craters of all sizes are noticeably absent in this image, indicating a relatively young age for this surface. This image is approximately 22 km wide and 60 km in length; north is toward the top. The Story If this wonderfully textured landform were on Earth, it would have to be designated as a 'national park,' much like the popular canyon parklands of the American Southwest. Look for the oblong plateau at the center right of this image, and see how the terrain descends from it on all sides. The southerly canyon wall (bottom third of the image) displays a visually beautiful canyon slope, with descending erosional flutes that cut pathways through the differently hued rock and mineral layers. While the northern side of the plateau might not look as dramatic, don't miss the dark-colored sand dunes that lie at the base of the canyon. Why did they form in just that place? To find out, look for the small hillock in the top left of the image that has interfered with the wind's flow, causing the ripply dunes to form. With so many interesting and physically stunning features

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

NASA Astrophysics Data System (ADS)

Twichell, David C.; Roberts, David G.

1982-08-01

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

Research Furthers Conservation of Grand Canyon Sandbars

USGS Publications Warehouse

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

2007-01-01

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

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

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

Bove, D.J.; Shawe, D.R.; Lee, G.K.

1989-01-01

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 undiscoveredmore » oil and gas and low resource potential for undiscovered metals, including uranium and thorium, coal, and geothermal energy.« less

AmeriFlux US-Vcm Valles Caldera Mixed Conifer

DOE Data Explorer

Litvak, Marcy [University of New Mexico

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-Vcm Valles Caldera Mixed Conifer. Site Description - The Valles Caldera Mixed Conifer site is located in the 1200 km2 Jemez River basin in north-central New Mexico. Common to elevations ranging from 3040 to 2740 m in the region, the mixed conifer stand, within the entirety of the tower footprint in all directions, provides an excellent setting for studying the seasonal interaction between snow and vegetation.

Environmental assessment: Davis Canyon site, Utah

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

none,

1986-05-01

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

Environmental assessment: Davis Canyon site, Utah

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

none,

1986-05-01

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

Environmental assessment: Davis Canyon site, Utah

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

none,

1986-05-01

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

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

NASA Astrophysics Data System (ADS)

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

2014-06-01

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

Hydrogeology of Middle Canyon, Oquirrh Mountains, Tooele County, Utah

USGS Publications Warehouse

Gates, Joseph Spencer

1963-01-01

Geology and climate are the principal influences affecting the hydrology of Middle Canyon, Tooele County, Utah. Reconnaissance in the canyon indicated that the geologic influences on the hydrology may be localized; water may be leaking through fault and fracture zones or joints in sandstone and through solution openings in limestone of the Oquirrh formation of Pennsylvanian and Permian age. Surficial deposits of Quaternary age serve as the main storage material for ground water in the canyon and transmit water from the upper canyon to springs and drains at the canyon mouth. The upper canyon is a more important storage area than the lower canyon because the surficial deposits are thicker, and any zones of leakage in the underlying bedrock of the upper canyon probably would result in greater leakage than would similar outlets in the lower canyon.The total annual discharge from Middle Canyon, per unit of precipitation, decreased between 1910 and 1939. Similar decreases occurred in Parleys Canyon in the nearby Wasatch Range and in other drainage basins in Utah, and it is likely that most of the decrease in discharge from Middle Canyon and other canyons in Utah is due to a change in climate.Chemical analyses of water showed that the high content of sulfate and other constituents in the water from the Utah Metals tunnel, which drains into Middle Canyon, does not have a significant effect on water quality at the canyon mouth. This suggests that much of the tunnel water is lost from the channel by leakage, probably in the upper canyon, during the dry part of the year.Comparison of the 150 acre-feet of water per square mile of drainage area discharged by Middle Canyon in 1947 with the 623 and 543 acre-feet per square mile discharged in 1948 by City Creek and Mill Creek Canyons, two comparable drainage basins in the nearby Wasatch Range, also suggests that there is leakage in Middle Canyon.A hydrologic budget of the drainage basin results in an estimate that about 3,000 acre

Multi-scale, multi-method geophysical investigations of the Valles Caldera

NASA Astrophysics Data System (ADS)

Barker, J. E.; Daneshvar, S.; Langhans, A.; Okorie, C.; Parapuzha, A.; Perez, N.; Turner, A.; Smith, E.; Carchedi, C. J. W.; Creighton, A.; Folsom, M.; Bedrosian, P.; Pellerin, L.; Feucht, D. W.; Kelly, S.; Ferguson, J. F.; McPhee, D.

2017-12-01

In 2016, the Summer of Applied Geophysical Experience (SAGE) program, in cooperation with the National Park Service, began a multi-year investigation into the structure and evolution of the Valles Caldera in northern New Mexico. The Valles Caldera is a 20-km wide topographic depression in the Jemez Mountains volcanic complex that formed during two massive ignimbrite eruptions at 1.65 and 1.26 Ma. Post-collapse volcanic activity in the caldera includes the rise of Redondo peak, a 1 km high resurgent dome, periodic eruptions of the Valles rhyolite along an inferred ring fracture zone, and the presence of a geothermal reservoir beneath the western caldera with temperatures in excess of 300°C at a mere 2 km depth. Broad sediment-filled valleys associated with lava-dammed Pleistocene lakes occupy much of the northern and southeastern caldera. SAGE activities to date have included collection of new gravity data (>120 stations) throughout the caldera, a transient electromagnetic (TEM) survey of Valle Grande, reprocessing of industrial magnetotelluric (MT) data collected in the 1980s, and new MT data collection both within and outside of the caldera. Gravity modeling provides constraints on the pre-Caldera structure, estimates of the thickness of Caldera fill, and reveals regional structural trends reflected in the geometry of post-Caldera collapse. At a more local scale, TEM-derived resistivity models image rhyolite flows radiating outward from nearby vents into the lacustrine sediments filling Valle Grande. Resistivity models along a 6-km long profile also provide hints of structural dismemberment along the inferred Valles and Toledo ring fracture zones. Preliminary MT modeling at the caldera scale reveals conductive caldera fill, the resistive crystalline basement, and an enigmatic mid-crustal conductor likely related to magmatic activity that post-dates caldera formation.

Near-Surface Geologic Units Exposed Along Ares Vallis and in Adjacent Areas: A Potential Source of Sediment at the Mars Pathfinder Landing Site

NASA Technical Reports Server (NTRS)

Treiman, Allan H.

1997-01-01

A sequence of layers, bright and dark, is exposed on the walls of canyons, impact craters and mesas throughout the Ares Vallis region, Chryse Planitia, and Xanthe Terra, Mars. Four layers can be seen: two pairs of alternating dark and bright albedo. The upper dark layer forms the top surface of many walls and mesas. The upper dark-bright pair was stripped as a unit from many streamlined mesas and from the walls of Ares Valles, leaving a bench at the top of the lower dark layer, approximately 250 m below the highland surface on streamlined islands and on the walls of Ares Vallis itself. Along Ares Vallis, the scarp between the highlands surface and this bench is commonly angular in plan view (not smoothly curving), suggesting that erosion of the upper dark-bright pair of layers controlled by planes of weakness, like fractures or joints. These near-surface layers in the Ares Vallis area have similar thicknesses, colors, and resistances to erosion to layers exposed near the tops of walls in Valles Marineris (Treiman et al.) and may represent the same pedogenic hardpan units. From this correlation, and from analogies with hardpans on Earth, the light-color layers may be cemented by calcite or gypsum. The dark layers are likely cemented by an iron-bearing mineral. Mars Pathfinder instruments should permit recognition and useful analyses of hardpan fragments, provided that clean uncoated surfaces are accessible. Even in hardpan-cemented materials, it should be possible to determine the broad types of lithologies in the Martian highlands. However, detailed geochemical modeling of highland rocks and soils may be compromised by the presence of hardpan cement minerals.

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

USGS Publications Warehouse

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

2012-01-01

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

Is Kasei Valles (Mars) the largest volcanic channel in the solar system?

NASA Astrophysics Data System (ADS)

Leverington, David W.

2018-02-01

With a length of more than 2000 km and widths of up to several hundred kilometers, Kasei Valles is the largest outflow system on Mars. Superficially, the scabland-like character of Kasei Valles is evocative of terrestrial systems carved by catastrophic aqueous floods, and the system is widely interpreted as a product of outbursts from aquifers. However, as at other Martian outflow channels, clear examples of fluvial sedimentary deposits have proven difficult to identify here. Though Kasei Valles lacks several key properties expected of aqueous systems, its basic morphological and contextual properties are aligned with those of ancient volcanic channels on Venus, the Moon, Mercury, and Earth. There is abundant evidence that voluminous effusions of low-viscosity magmas occurred at the head of Kasei Valles, the channel system acted as a conduit for associated flows, and mare-style volcanic plains developed within its terminal basin. Combined mechanical and thermal incision rates of at least several meters per day are estimated to have been readily achieved at Kasei Valles by 20-m-deep magmas flowing with viscosities of 1 Pa s across low topographic slopes underlain by bedrock. If Kasei Valles formed through incision by magma, it would be the largest known volcanic channel in the solar system. The total volume of magma erupted at Kasei Valles is estimated here to have possibly reached or exceeded ∼5 × 106 km3, a volume comparable in magnitude to those that characterize individual Large Igneous Provinces on Earth. Development of other large outflow systems on Mars is expected to have similarly involved eruption of up to millions of cubic kilometers of magma.

Recurring slope lineae in equatorial regions of Mars

USGS Publications Warehouse

McEwen, Alfred S.; Dundas, Colin M.; Mattson, Sarah S.; Toigo, Anthony D.; Ojha, Lujendra; Wray, James J.; Chojnacki, Matthew; Byrne, Shane; Murchie, Scott L.; Thomas, Nicolas

2014-01-01

The presence of liquid water is a requirement of habitability on a planet. Possible indicators of liquid surface water on Mars include intermittent flow-like features observed on sloping terrains. These recurring slope lineae are narrow, dark markings on steep slopes that appear and incrementally lengthen during warm seasons on low-albedo surfaces. The lineae fade in cooler seasons and recur over multiple Mars years. Recurring slope lineae were initially reported to appear and lengthen at mid-latitudes in the late southern spring and summer and are more common on equator-facing slopes where and when the peak surface temperatures are higher. Here we report extensive activity of recurring slope lineae in equatorial regions of Mars, particularly in the deep canyons of Valles Marineris, from analysis of data acquired by the Mars Reconnaissance Orbiter. We observe the lineae to be most active in seasons when the slopes often face the sun. Expected peak temperatures suggest that activity may not depend solely on temperature. Although the origin of the recurring slope lineae remains an open question, our observations are consistent with intermittent flow of briny water. Such an origin suggests surprisingly abundant liquid water in some near-surface equatorial regions of Mars.

Geologic map of Ophir and central Candor Chasmata (MTM -05072) of Mars

USGS Publications Warehouse

Lucchitta, Baerbel K.

1999-01-01

The geologic map of Ophir and central Candor Chasmata is one of a series of 1:500,000 scale maps prepared for areas on Mars that are of particular scientific interest and may serve as potential future landing sites. This map is also part of a set that includes east Candor Chasma, west Candor Chasma, and Melas Chasma. The geologic interpretations are based dominantly on medium- and high-resolution Viking images, many of them stereoscopic, and supplemented by lower resolution apoapsis and other color images. A strip of very high resolution stereoscopic images (~20 m/pixel) crosses the central part of the quadrangle from northwest to southeast and served to clarify detailed relations not obvious on other images. A topographic map with contour intervals of 200 m was also used, as were multidirectional oblique images derived from merged image mosaics and topography (see fig. 1) (Bertolini and McEwen, 1990). Geologic relations and interpretations are based on the entire central Valles Marineris map set. The map area is included in the Valles Marineris map of Witbeck and others (1991), but units were defined independently. Age assignments, however, were integrated with those by Witbeck and others and Scott and Tanaka (1986).

Searching for Aqueous Activity on Mars through Analyses of OMEGA Spectra

NASA Astrophysics Data System (ADS)

Bishop, J. L.; Bibring, J.-P.; Dyar, M. D.; Gendrin, A.; Lane, M. D.; Mustard, J. F.; Parente, M.; Poulet, F.

2005-08-01

Analyses of OMEGA spectra have shown the presence of sulfate and clay minerals in a number of regions including Valles Marineris, Nili Fossae and Terra Meridiani (1-4). We are searching for spectral features associated with these minerals in OMEGA image cubes and are using expanded spectral libraries to further characterize these features. Shown below are three OMEGA spectra from the Valles Marineris and Syrtis Major regions, identified from top to bottom as containing kieserite, nontronite, and polyhydrated sulfates (2,3). They are compared in the figure with spectra of nontronite and of the hydrous sulfate minerals szomolnokite (Fe2+SO4H2O kieserite group) and rozenite (Fe2+S44H2O starkeyite group). We seek to identify and characterize areas on Mars where it is possible to refine the mineralogical interpretations. We are searching for locations where minerals such as szomolnokite or rozenite may be the spectrally dominant component in spectra characterized so far as monohydrated and polyhydrated sulfates. 1) J.-P. Bibring et al., Science 307, 1576 (2005). 2) A. Gendrin et al., 2nd Conf. on Early Mars, Jackson Hole, Wyoming 2004. 3) A. Gendrin et al., Science 307, 1587 (2005). 4) J. F. Mustard et al., LPSC #1341 (2005).

Submarine sand dunes and sedimentary environments in Oceanographer Canyon.

USGS Publications Warehouse

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

1984-01-01

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

The Black Canyon of the Gunnison: Today and Yesterday

USGS Publications Warehouse

Hansen, Wallace R.

1965-01-01

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

Granicus Valles

NASA Image and Video Library

2002-12-16

The force of moving water from a flood carved these teardrop-shaped islands within Granicus Valles. The orientation of the islands can be used as an indicator of the direction the water flowed. In this case, the water flowed primarily towards the upper left of the image. The image also contains many narrow sinuous channels. Geologists can determine that the floods occurred before a later tectonic event in the region. This event caused the crust to fracture into numerous blocks and fissures (grabens). Many fissures can be seen cutting across the former flood pathways. http://photojournal.jpl.nasa.gov/catalog/PIA04037

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

NASA Astrophysics Data System (ADS)

Nasıf, Aslıhan; Dondurur, Derman

2017-04-01

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

Noctis Landing: A Proposed Landing Site/Exploration Zone for Human Missions to the Surface of Mars

NASA Technical Reports Server (NTRS)

Lee, Pascal; Acedillo, Shannen; Braham, Stephen; Brown, Adrian; Elphic, Richard; Fong, Terry; Glass, Brian; Hoftun, Christopher; Johansen, Brage W.; Lorber, Kira;

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

USGS Publications Warehouse

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

2005-01-01

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

Geologic support for the putative Borealis basin (Mega-Impact) on Mars

NASA Astrophysics Data System (ADS)

Bleamaster, L. F.

2008-12-01

A series of recent papers (all in Nature v. 453) using Martian gravity and topography [Andrews-Hanna et al., 2008], 3-D hydrodynamic simulations [Marinova et al., 2008], and 2-D hydrocode models [Nimmo et al., 2008] have eloquently reintroduced the single mega-impact hypothesis for the formation of the Martian hemispheric dichotomy boundary. Although geophysical models often return non-unique solutions, the coalition front presented by these three independent methods to test such a hypothesis lends credibility and demands further evaluation. The central tenet of these works is the proposition that an elliptical basin (long axis 10,600km, ellipticity 1.25) centered at 67N, 208E marks the pre-Tharsis crustal thickness transition and thus the real dichotomy boundary. Evaluation of this new boundary with respect to the geologic record offers new avenues, especially since geologic tests of the mega-impact hypothesis have mostly proved inconclusive because of Mars' multi-stage and multi-process geologic history. Within this survey, a slightly larger ellipse with a long axis of 12,500 km, ellipticity of 1.48, and centered at 65.3N, 250E expands the putative Borealis impact basin (which does not necessarily represent the transient or final impact cavity dimensions, but defines a potential 'affected zone') while maintaining agreement with the original observations with respect to gravity and topography. The 'affected zone' can be defined by basement structure that may become susceptible to later deformation, or it may in fact have been the paleo- topographic expression of the basin. By expanding the overall area (nearly twice the area of the original mega-impact basin proposed by Wilhelms and Squyres in 1984) several geologic features become significant in evaluating the mega-impact story. 1) Valles Marineris is concentric to the putative basin interior and parallels the ellipse margin suggesting that it is the structural manifestation of localized crustal relaxation of the

Ventilation Processes in a Three-Dimensional Street Canyon

NASA Astrophysics Data System (ADS)

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

2016-05-01

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

Maja Valles, Mars: A Multi-Source Fluvio-Volcanic Outflow Channel System

NASA Astrophysics Data System (ADS)

Keske, A.; Christensen, P. R.

2017-12-01

The resemblance of martian outflow channels to the channeled scablands of the Pacific Northwest has led to general consensus that they were eroded by large-scale flooding. However, the observation that many of these channels are coated in lava issuing from the same source as the water source has motivated the alternative hypothesis that the channels were carved by fluid, turbulent lava. Maja Valles is a circum-Chryse outflow channel whose origin was placed in the late Hesperian by Baker and Kochel (1979), with more recent studies of crater density variations suggesting that its formation history involved multiple resurfacing events (Chapman et al., 2003). In this study, we have found that while Maja Valles indeed host a suite of standard fluvial landforms, its northern portion is thinly coated with lava that has buried much of the older channel landforms and overprinted them with effusive flow features, such as polygons and bathtub rings. Adjacent to crater pedestals and streamlined islands are patches of dark, relatively pristine material pooled in local topographic lows that we have interpreted as ponds of lava remaining from one or more fluid lava flows that flooded the channel system and subsequently drained, leaving marks of the local lava high stand. Despite the presence of fluvial landforms throughout the valles, lava flow features exist in the northern reaches of the system alone, 500-1200 km from the channels' source. The flows can instead be traced to a collection of vents in Lunae Plaum, west of the valles. In previously studied fluvio-volcanic outflow systems, such as Athabasca Valles, the sources of the volcanic activity and fluvial activity have been indistinguishable. In contrast, Maja Valles features numerous fluvio-volcanic landforms bearing similarity to those identified in other channel systems, yet the source of its lava flows is distinct from the source of its channels. Furthermore, in the absence of any channels between the source of the lava

Geology and biology of Oceanographer submarine canyon.

USGS Publications Warehouse

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

1980-01-01

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

Discovery of two new large submarine canyons in the Bering Sea

USGS Publications Warehouse

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

1984-01-01

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

Chapter 12. Canyons microbiology studies

USGS Publications Warehouse

Kellogg, Christina A.; Lawler, Stephanie N.

2017-01-01

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

36 CFR 7.19 - Canyon de Chelly National Monument.

Code of Federal Regulations, 2011 CFR

2011-07-01

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

36 CFR 7.19 - Canyon de Chelly National Monument.

Code of Federal Regulations, 2010 CFR

2010-07-01

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

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

USGS Publications Warehouse

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

2010-01-01

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

Geologic Mapping of Athabasca Valles

NASA Technical Reports Server (NTRS)

Keszthelyi, L. P.; Jaeger, W. L.; Tanaka, K.; Hare, T.

2009-01-01

We are approaching the end of the third year of mapping the Athabasca Valles region of Mars. The linework has been adjusted in response to new CTX images and we are on schedule to submit the 4 MTM quads (05202, 05207, 10202, 10207) and ac-companying paper by the end of this fiscal year.

Morphodynamic Model of Submarine Canyon Incision by Sandblasting

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Arsinoes Chaos Landforms

NASA Technical Reports Server (NTRS)

2004-01-01

23 October 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned rock outcrops, possibly sedimentary rocks, in the Arsinoes Chaos region east of the Valles Marineris trough system. These rocky materials were once below the martian surface. These features are located near 7.2oS, 27.9oW. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.

Landslide in Coprates

NASA Technical Reports Server (NTRS)

2004-01-01

15 November 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the distal (far) end of a landslide deposit in Coprates Chasma, part of the vast Valles Marineris trough system. Large boulders, the size of buildings, occur on the landslide surface. This October 2004 picture is located near 15.3oS, 54.6oW, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.

Turbulent Lava Flow in Mars Athabasca Valles

NASA Image and Video Library

2010-01-11

This combination of images, taken by NASA Mars Reconnaissance Orbiter, helped researchers analyze the youngest flood lava on Mars, which is in Athabasca Valles, in the Elysium Planitia region of equatorial Mars.

Warrego Valles

NASA Technical Reports Server (NTRS)

2004-01-01

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.

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

USGS Publications Warehouse

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

2015-01-01

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

Why SRS Matters - H Canyon

ScienceCinema

Hunt, Paul; Lewczyk, Mike; Swain, Mike

2018-06-22

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

The central uplift of Ritchey crater, Mars

NASA Astrophysics Data System (ADS)

Ding, Ning; Bray, Veronica J.; McEwen, Alfred S.; Mattson, Sarah S.; Okubo, Chris H.; Chojnacki, Matthew; Tornabene, Livio L.

2015-05-01

Ritchey crater is a ∼79 km diameter complex crater near the boundary between Hesperian ridged plains and Noachian highland terrain on Mars (28.8°S, 309.0°E) that formed after the Noachian. High Resolution Imaging Science Experiment (HiRISE) images of the central peak reveal fractured massive bedrock and megabreccia with large clasts. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectral analysis reveals low calcium pyroxene (LCP), olivine (OL), hydrated silicates (phyllosilicates) and a possible identification of plagioclase bedrock. We mapped the Ritchey crater central uplift into ten units, with 4 main groups from oldest and originally deepest to youngest: (1) megabreccia with large clasts rich in LCP and OL, and with alteration to phyllosilicates; (2) massive bedrock with bright and dark regions rich in LCP or OL, respectively; (3) LCP and OL-rich impactites draped over the central uplift; and (4) aeolian deposits. We interpret the primitive martian crust as igneous rocks rich in LCP, OL, and probably plagioclase, as previously observed in eastern Valles Marineris. We do not observe high-calcium pyroxene (HCP) rich bedrock as seen in Argyre or western Valles Marineris. The association of phyllosilicates with deep megabreccia could be from impact-induced alteration, either as a result of the Richey impact, or alteration of pre-existing impactites from Argyre basin and other large impacts that preceded the Ritchey impact, or both.

Quantifying widespread aqueous surface weathering on Mars: The plateaus south of Coprates Chasma

NASA Astrophysics Data System (ADS)

Loizeau, D.; Quantin-Nataf, C.; Carter, J.; Flahaut, J.; Thollot, P.; Lozac'h, L.; Millot, C.

2018-03-01

Pedogenesis has been previously proposed on the plateaus around Coprates Chasma, Valles Marineris to explain the presence of widespread clay sequences with Al-clays and possible hydrated silica over Fe/Mg-clays on the surface of the plateaus (Le Deit et al., 2012; Carter et al., 2015). We use previous observations together with new MRO targeted observations and DEMs to constrain the extent and thickness of the plateau clay unit: the Al-clay unit is less than 3 m thick, likely ∼1 m, while the Fe/Mg-clays underneath are few tens of meters thick. We also refine the age of alteration by retrieving crater retention ages of the altered plateau and of later deposits: the observed clay sequence was created by surface pedogenesis between model ages of 4.1 Ga and 3.75 Ga. Using a leaching model from Zolotov and Mironenko (2016), we estimate the quantity of atmospheric precipitations needed to create such a clay sequence, that strongly depends on the chemistry of the precipitating fluid. A few hundreds of meters of cumulated precipitations of highly acidic fluids could explain the observed clay sequence, consistent with estimates based on late Noachian valley erosion for example (Rosenberg and Head, 2015). We show finally that the maximum quantity of sulfates potentially formed during this surface weathering event can only contribute minimally to the volume of sulfates deposited in Valles Marineris.

The central uplift of Ritchey crater, Mars

USGS Publications Warehouse

Ding, Ning; Bray, Veronica J.; McEwen, Alfred S.; Mattson, Sarah S.; Okubo, Chris H.; Chojnacki, Matthew; Tornabene, Livio L.

2015-01-01

Ritchey crater is a ∼79 km diameter complex crater near the boundary between Hesperian ridged plains and Noachian highland terrain on Mars (28.8°S, 309.0°E) that formed after the Noachian. High Resolution Imaging Science Experiment (HiRISE) images of the central peak reveal fractured massive bedrock and megabreccia with large clasts. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectral analysis reveals low calcium pyroxene (LCP), olivine (OL), hydrated silicates (phyllosilicates) and a possible identification of plagioclase bedrock. We mapped the Ritchey crater central uplift into ten units, with 4 main groups from oldest and originally deepest to youngest: (1) megabreccia with large clasts rich in LCP and OL, and with alteration to phyllosilicates; (2) massive bedrock with bright and dark regions rich in LCP or OL, respectively; (3) LCP and OL-rich impactites draped over the central uplift; and (4) aeolian deposits. We interpret the primitive martian crust as igneous rocks rich in LCP, OL, and probably plagioclase, as previously observed in eastern Valles Marineris. We do not observe high-calcium pyroxene (HCP) rich bedrock as seen in Argyre or western Valles Marineris. The association of phyllosilicates with deep megabreccia could be from impact-induced alteration, either as a result of the Richey impact, or alteration of pre-existing impactites from Argyre basin and other large impacts that preceded the Ritchey impact, or both.

Pollutant Dilution and Diffusion in Urban Street Canyon Neighboring Streets

NASA Astrophysics Data System (ADS)

Sun, Z.; Fu, Zh. M.

2011-09-01

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

Anatomy of La Jolla submarine canyon system; offshore southern California

USGS Publications Warehouse

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

2013-01-01

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

Rates and drivers of erosion in the Southern Pyrenees: a 10Be-supported model for the Valle de la Fueva catchments

NASA Astrophysics Data System (ADS)

Stange, Kurt Martin; Midtkandal, Ivar; Petter Nystuen, Johan; Sohbati, Reza; Murray, Andrew Sean; Spiegel, Cornelia; Kuss, Jochen

2017-04-01

Intramontane basins are typical features of every mountain chain. These topographic depressions function as sediment traps during the syn- and postorogenic evolution of a range. Hence, studying their sedimentary archives and morphogenetic development may deliver important insights into the dynamics and magnitudes of erosion-sedimentation processes in mountain catchments and their susceptibility towards changing environmental conditions. Aiming at quantifying Quaternary catchment erosion rates in the Southern Pyrenees and determining the timing and driving parameters of basin excavation stages, this research project focusses on a number of adjacent watersheds in the Valle de la Fueva in Aragon, Spain. Besides providing a comprehensive OSL and 10Be-supported catchment erosion model, potential relationships of intense late stage erosion phases with watershed capture, base level changes and climatic controls are addressed. The Valle de la Fueva comprises a number of sub-catchments of the Ainsa depression - an Eocene sedimentary basin situated in the southern Pyrenean fold and thrust belt (SPFZ) which is recognized as a prime analogue for reservoir geometries and turbidite systems. The Valle de la Fueva is a highly erodible catchment, typical for the SPFZ with its shallow and deep marine strata, conglomerates and synorogenic debris. Preliminary observations revealed systems of "cut-in-fill" alluvial terraces and residual erosion surfaces - i.e. pediments and glacis that are strongly dissected by gullies and barrancos. Basin outlet canyons are deeply entrenched into the Los Molinos thrust front and represent dramatic landscape features that are relevant to the base level and opening history of the Valle de la Fueva catchments. Combining digital terrain analysis with field surveys and exposure/burial dating, first results revealed differences in stream profile gradation and incision magnitudes among several sub-catchments. Since they share a common base level, the main

Ridges near Nirgal Valles

NASA Image and Video Library

2018-03-05

In this observation from NASA's Mars Reconnaissance Orbiter (MRO), we see a set of straight ridges in ancient bedrock near Nirgal Valles. The patterns indicate fractures from tectonic stresses, but how have they been hardened to now stand in positive relief after billions of years of erosion? It is possible that groundwater flowed through the fractures, depositing various durable minerals, some of which we see in diverse colors. https://photojournal.jpl.nasa.gov/catalog/PIA22333

Bottom-trawling along submarine canyons impacts deep sedimentary regimes.

PubMed

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

2017-02-24

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

Hot Canyon

ScienceCinema

None

2018-05-07

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

Ectopsocidae (Psocodea: 'Psocoptera') from Valle del Cauca and NNP Gorgona, Colombia.

PubMed

Manchola, Oscar Fernando Saenz; Obando, Ranulfo González; Aldrete, Alfonso N García

2014-04-14

The results of a survey of the psocid family Ectopsocidae in Valle del Cauca and NNP Gorgona, are here presented. Fifteen species were identified, in the genera Ectopsocus (14 species), and Ectopsocopsis (one species); four of the Ectopsocus species are new to science and are here described and illustrated. The male of E. thorntoni García Aldrete is here described. Records of Ectopsocopsis cryptomeriae (Enderlein), Ectopsocus briggsi McLachlan, E. californicus Banks, E. columbianus Badonnel, E. maindroni Badonnel, E. meridionalis Ribaga, E. pilosus Badonnel, E. richardsi Pearman, E. titschacki Jentsch, and E. vilhenai Badonnel, are provided. Ten species were found only in Valle del Cauca, two species were found only in the NNP Gorgona, and three species were found at both sites. The specimens studied are deposited in the Entomological Museum, Universidad del Valle, Santiago de Cali, Colombia (MUSENUV).

Recreational impacts on Colorado River beaches in Glen Canyon, Arizona

NASA Astrophysics Data System (ADS)

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

1984-07-01

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

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

NASA Astrophysics Data System (ADS)

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

1999-08-01

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

Advances in Planetary Geology

NASA Technical Reports Server (NTRS)

Grant, John A., III; Nedell, Susan S.

1987-01-01

The surface of Mars displays a broad range of channel and valley features. There is as great a range in morphology as in scale. Some of the features of Martian geography are examined. Geomorphic mapping, crater counts on selected surfaces, and a detailed study of drainage basins are used to trace the geologic evolution of the Margaritifer Sinus Quandrangle. The layered deposits in the Valles Marineris are described in detail and the geologic processes that could have led to their formation are analyzed.

Colorful Equatorial Gullies in Krupac Crater

NASA Image and Video Library

2017-05-02

Although large gullies (ravines) are concentrated at higher latitudes, there are gullies on steep slopes in equatorial regions, as seen in this image captured by NASA's Mars Reconnaissance Orbiter (MRO). The colors of the gully deposits match the colors of the eroded source materials. Krupac is a relatively young impact crater, but exposes ancient bedrock. Krupac Crater also hosts some of the most impressive recurring slope lineae (RSL) on equatorial Mars outside of Valles Marineris. https://photojournal.jpl.nasa.gov/catalog/PIA21605

An overview of the Valles Caldera National Preserve: the natural and cultural resources

USGS Publications Warehouse

Parmenter, Robert R.; Steffen, Anastasia; Allen, Craig D.; Kues, Barry S.; Kelley, Shari A.; Lueth, Virgil W.

2007-01-01

The Valles Caldera National Preserve is one of New Mexico’s natural wonders and a popular area for public recreation, sustainable natural resource production, and scientific research and education. Here, we provide a concise overview of the natural and cultural history of the Preserve, including descriptions of the ecosystems, flora and fauna. We note that, at the landscape scale, the Valles caldera appears to be spectacularly pristine; however, humans have extracted resources from the Preserve area for many centuries, resulting in localized impacts to forests, grasslands and watersheds. The Valles Caldera Trust is now charged with managing the Preserve and providing public access, while preserving and restoring these valuable public resources.

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

Grand Canyon Humpback Chub Population Improving

USGS Publications Warehouse

Andersen, Matthew E.

2007-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

Characteristics of flow and reactive pollutant dispersion in urban street canyons

NASA Astrophysics Data System (ADS)

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

2015-05-01

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

7. DARK CANYON SIPHON Photographic copy of construction drawing ...

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

7. DARK CANYON SIPHON - Photographic copy of construction drawing c1907 (from Record Group 115, Box 17, Denver Branch of the National Archives, Denver) DARK CANYON SIPHON PLAN, ELEVATION, AND SECTIONS - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

5. DARK CANYON SIPHON Photographic copy of historic photo, ...

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

5. DARK CANYON SIPHON - Photographic copy of historic photo, November 11, 1906 (original print located at the Carlsbad Irrigation District offices, Carlsbad, New Mexico) photographer unknown 'LOWER END OF DARK CANYON SIPHON CONSTRUCTION' - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

The Martian, Part 2: Mawrth Valles

NASA Image and Video Library

2015-10-13

All this week, the THEMIS Image of the Day is following on the real Mars the path taken by fictional astronaut Mark Watney, stranded on the Red Planet in the book and movie, The Martian. Today's image shows part of Mawrth Valles, a channel carved by giant floods billions of years ago. The highlands lying to the south and west of the channel are under consideration as a potential landing site for NASA's Mars 2020 rover. Remote-sensing observations from orbit show widespread exposures of clay minerals, indicating alteration by water early in Martian history. These might preserve traces of ancient life, if there was any. For astronaut Mark Watney, driving in a pressurized and solar-powered rover vehicle, Mawrth Valles offers a gentle slope and an easy-to-follow route up from Acidalia's low-lying plains into the Arabia Terra highlands. At this point in his journey, he has driven about 750 kilometers (470 miles). Orbit Number: 38563 Latitude: 24.4297 Longitude: 341.726 Instrument: VIS Captured: 2010-08-24 14:56 http://photojournal.jpl.nasa.gov/catalog/PIA19797

Tectonic history of the Syria Planum province of Mars

USGS Publications Warehouse

Tanaka, K.L.; Davis, P.A.

1988-01-01

We attribute most of the development of extensive fractures in the Tharsis region to discrete tectonic provinces within the region, rather than to Tharsis as a single entity. One of these provinces is in Syria Planum. Faults and collapse structures in the Syria Planum tectonic province on Mars are grouped into 13 sets based on relative age, areal distribution, and morphology. According to superposition and fault crosscutting relations and crater counts we designate six distinct episodes of tectonic activity. Photoclinometric topographic profiles across 132 grabens and fault scarps show that Syria Planum grabens have widths (average of 2.5 km, and most range from 1 to 6 km) similar to lunar grabens, but the Martian grabens have slightly higher side walls (average abour 132 m) and gentler wall slopes (average of 9?? and range of 2??-25??) than lunar grabens (93 m high and 18?? slopes). Estimates of the amount of extension for individual grabens range from 20 to 350 m; most estimates of the thickness of the faulted layer range from 0.5 to 4.5 km (average is 1.5 km). This thickness range corresponds closely to the 0.8- to 3.6-km range in depth for pits, troughs, and canyons in Noctis Labyrinthus and along the walls of Valles Marineris. We propose that the predominant 1- to 1.5-km values obtained for both the thickness of the faulted layer and the depths of the pits, troughs, and theater heads of the canyons reflect the initial depth to the water table in this region, as governed by the depth to the base of ground ice. Maximum depths for these features may indicate lowered groundwater table depths and the base of ejecta material. -from Authors

Ares Valles

NASA Image and Video Library

2002-12-13

This image from NASA Mars Odyssey covers a portion of Ares Valles, an outflow channel carved into the surface of Mars by ancient catastrophic floods. The floods were most likely caused by huge discharges of groundwater at the channel heads. These floods are similar to (but much larger than) floods that created the Channeled Scablands in central Washington State during the last ice age on Earth. The Martian channels are hundreds of kilometers long and occur in a number of regions within equatorial Mars. The material that was eroded away by these floods was deposited as sediment in the northern lowlands. The Mars Pathfinder landing site is several hundred kilometers downstream from the location of this image and the surfaces are probably similar in nature. http://photojournal.jpl.nasa.gov/catalog/PIA04026

Bottom-trawling along submarine canyons impacts deep sedimentary regimes

PubMed Central

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

2017-01-01

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

Bottom-trawling along submarine canyons impacts deep sedimentary regimes

NASA Astrophysics Data System (ADS)

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

2017-02-01

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

Active geologic processes in Barrow Canyon, northeast Chukchi Sea

USGS Publications Warehouse

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

1982-01-01

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

Shed Some Light on the Subject: Teaching Ramon del Valle-Inclan's "Luces de bohemia"

ERIC Educational Resources Information Center

Parker, Jason Thomas

2011-01-01

This essay seeks to provide parallel and interchangeable approaches to teaching Ramon del Valle-Inclan's challenging play "Luces de bohemia". A greater understanding of the cultural and mental frameworks of the early twentieth-century Spanish spectator will permit students to penetrate the dense intertextuality that characterizes Valle's…

Mega-geomorphology: Mars vis a vis Earth

NASA Technical Reports Server (NTRS)

Sharp, R. P.

1985-01-01

The areas of chaotic terrain, the giant chasma of the Valles Marineris region, the complex linear and circular depressions of Labyrinthus Noctis on Mars all suggest the possibility of large scale collapse of parts of the martian crust within equatorial and sub equatorial latitudes. It seems generally accepted that the above features are fossil, being perhaps, more than a billion years old. It is possible that parts of Earth's crust experienced similar episodes of large scale collapse sometime early in the evolution of the planet.

Perspective view over the Grand Canyon, Arizona

NASA Image and Video Library

2001-10-22

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

6. DARK CANYON SIPHON Photographic copy of historic photo, ...

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

6. DARK CANYON SIPHON - Photographic copy of historic photo, January 29, 1907 (original print filed in Record Group 115, National Archives, Washington, D.C.) W.J.Lubken, photographer 'RIPRAP AT THE ENTRANCE END OF DARK CANYON PRESSURE PIPE' - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Observations of environmental change in Grand Canyon, Arizona

USGS Publications Warehouse

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

2002-01-01

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

Grand Canyon, Lake Powell, and Lake Mead

NASA Technical Reports Server (NTRS)

2002-01-01

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

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

PubMed Central

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

2014-01-01

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

Digital structural

USGS Publications Warehouse

Dohm, J.M.; Anderson, R.C.; Tanaka, K.L.

1998-01-01

Magmatic and tectonic activity have both contributed significantly to the surface geology of Mars. Digital structural mapping techniques have now been used to classify and date centers of tectonic activity in the western equatorial region. For example, our results show a center of tectonic activity at Valles Marineris, which may be associated with uplift caused by intrusion. Such evidence may help explain, in part, the development of the large troughs and associated outflow channels and chaotic terrain. We also find a local centre of tectonic activity near the source region of Warrego Valles. Here, we suggest that the valley system may have resulted largely from intrusive-related hydrothermal activity. We hope that this work, together with the current Mars Global Surveyor mission, will lead to a better understanding of the geological processes that shaped the Martian surface.

Crossing fitness canyons by a finite population

NASA Astrophysics Data System (ADS)

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

2017-06-01

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

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

PubMed

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

2012-02-01

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

Fault Networks in the Northwestern Albuquerque Basin and Their Potential Role in Controlling Mantle CO2 Degassing and Fluid Migration from the Valles Caldera

NASA Astrophysics Data System (ADS)

Smith, J. R.; Crossey, L. J.; Karlstrom, K. E.; Fischer, T. P.; Lee, H.; McGibbon, C. J.

2015-12-01

The Rio Grande rift (RGR) has Quaternary and active volcanism and faulting that provide a field laboratory for examining links between mantle degassing and faults as fluid conduits. Diffuse and spring CO2 flux measurements were taken at 6 sites in the northwestern Albuquerque Basin (NWAB) and Valles caldera geothermal system. All sites progress to the southwest from the 1.25 Ma Valles caldera, down the rift-related Jemez fault network, to intersect with the Nacimiento fault system. Mantle CO2 and He degassing are well documented at 5 of 6 sites, with decreasing 3He/4He ratios away from the caldera. The instrument used to measure CO2 flux was an EGM-4 CO2 gas analyzer (PP systems) with an accumulation chamber. Carbonic springs at Penasco Springs (PS) and San Ysidro (SY), and the carbonate-cemented Sand Hill Fault (SHF) were targeted, all near the western border of the RGR. The SHF has no spring activity, had the smallest maximum flux of all the sites (8 g/m2d), but carbonate along the fault zone (<2 m wide) attest to past CO2 flux. The other two sites are equal distance (30-40 km) between the SHF site and Valles caldera sites. These sites have active carbonic springs that precipitate travertine mounds. Our work suggests these sites reflect intersections of the Nacimiento fault with NE trending faults that connect to the Jemez fault network. The maximum diffuse flux recorded at SY (297 g/m2d) and PS (25 g/m2d) are high, especially along the fault and near springs. At SY and PS the instruments capacity was exceeded (2,400 g/m2d) at 6 of 9 springs. Interpretations indicate a direct CO2 flux through a fault-related artesian aquifer system that is connected to magmatic gases from the caldera. Maximum diffuse flux measurements of Alamo Canyon (20,906 g/m2d), Sulphur Springs (2,400 g/m2d) and Soda Dam (1,882 g/m2d) at Valles caldera geothermal sites are comparable to Yellowstone geothermal systems. We use geospatial analysis and local geologic mapping to examine

Episodes of fluvial and volcanic activity in Mangala Valles, Mars

PubMed Central

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

2017-01-01

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. PMID:29176911

Episodes of fluvial and volcanic activity in Mangala Valles, Mars.

PubMed

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

2015-01-01

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.

West Candor Chasma

NASA Technical Reports Server (NTRS)

1996-01-01

During its examination of Mars, the Viking 1 spacecraft returned images of Valles Marineris, a huge canyon system 5,000 km long, up to 240 km wide, and 6.5 km deep, whose connected chasma or valleys may have formed from a combination of erosional collapse and structural activity. The view shows west Candor Chasma, one of the connected valleys of Valles Marineris; north toward top of frame. The image is a composite of Viking high-resolution (about 80 m/pixel or picture element) images in black and white and low resolution (about 250 m/pixel) images in color. The Viking 1 craft landed on Mars in July of 1976. West Candor Chasma occupies the westernmost part of the large west-northwest-trending trough of Candor Chasma. This section is about 150 km wide. West Candor Chasma is bordered on the north and south by straight-walled cliffs, most likely faults, and on its west by two segments of north-northeast-trending cliffs. The north wall is dissected by landslide scars forming reentrants filled with landslide debris. The south wall shows spur-and-gully morphology and smooth sections. The high-standing central mesa, informally dubbed Red Mesa has several curvilinear reentrants carved into the caprock, whose anomalously colored layers were interpreted to be caused by young hydrothermal alteration products (Geissler et al., 1993, Icarus, v. 106, p. 380-391). Light-colored lobes flow away from the top of the interior stack and then flow around and embay the same layered stack from which they originated. One of these apparent flow features is composed of at least two or perhaps even three huge, superposed, vaguely layered, very rugged, light-colored lobes as much as 100 km long, 20 km wide, and over 2 km thick. The layered deposits below the caprock also merge with a chaotic material that has local lobate fronts and overlaps landslide deposits. Hummocky material, similar in hue to wall rock, fills the southwestern-most region of west Candor Chasma and is perhaps as much as 3

Investigating Mars: Hebes Chasma

NASA Image and Video Library

2017-08-14

This image shows the part of the southern cliff face of Hebes Chasma a the bottom of the image. At the top of the image is part of the large mesa located in the center of the chasma. Hebes Chasma is an enclosed basin not connected to Valles Marineris. The cliff faces of the chasma itself and the interior mesa appear quite different, which may provided information on how the chasma and the mesa formed. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 10052 Latitude: -1.5441 Longitude: 283.71 Instrument: VIS Captured: 2004-03-21 00:22 https://photojournal.jpl.nasa.gov/catalog/PIA21809

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

USGS Publications Warehouse

Sondossi, Hoda A.; Fairley, Helen C.

2014-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2011-12-01

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

Pits and Channels of Hebrus Valles

NASA Image and Video Library

2017-01-26

The drainages in this image are part of Hebrus Valles, an outflow channel system likely formed by catastrophic floods. Hebrus Valles is located in the plains of the Northern lowlands, just west of the Elysium volcanic region. Individual channels range from several hundred meters to several kilometers wide and form multi-threaded (anastamosing) patterns. Separating the channels are streamlined forms, whose tails point downstream and indicate that channel flow is to the north. The channels seemingly terminate in an elongated pit that is approximately 1875 meters long and 1125 meters wide. Using the shadow that the wall has cast on the floor of the pit, we can estimate that the pit is nearly 500 meters deep. The pit, which formed after the channels, exposes a bouldery layer below the dusty surface mantle and is underlain by sediments. Boulders several meters in diameter litter the slopes down into the pit. Pits such as these are of interest as possible candidate landing sites for human exploration because they might retain subsurface water ice (Schulze-Makuch et al. 2016, 6th Mars Polar Conf.) that could be utilized by future long-term human settlements. http://photojournal.jpl.nasa.gov/catalog/PIA11704

Spatial and Temporal Variation in DeSoto Canyon Macrofaunal Community Structure

NASA Astrophysics Data System (ADS)

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

2016-02-01

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

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

USGS Publications Warehouse

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

2017-08-29

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

NASA Satellite Reveals Grandeur of Arizona Grand Canyon

NASA Image and Video Library

2011-10-14

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

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

USGS Publications Warehouse

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

2002-01-01

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

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

NASA Astrophysics Data System (ADS)

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

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

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

USGS Publications Warehouse

Twichell, David C.

1983-01-01

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

H CANYON PROCESSING IN CORRELATION WITH FH ANALYTICAL LABS

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

Weinheimer, E.

2012-08-06

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

Geologic Mapping of Athabasca Valles

NASA Technical Reports Server (NTRS)

Keszthelyi, L. P.; Jaeger, W. L.; Tanaka, K.; Hare, T.

2008-01-01

Two factors drive us to map the Athabasca Valles area in unusual detail: (1) the extremely well-preserved and exposed surface morphologies and (2) the extensive high resolution imaging. In particular, the near-complete CTX coverage of Athabasca Valles proper and the extensive coverage of its surroundings have been invaluable. The mapping has been done exclusively in ArcGIS, using individual CTX, THEMIS VIS, and MOC frames overlying the THEMIS IR daytime basemap. MOLA shot points and gridded DTMs are also included. It was found that CTX images processed through ISIS are almost always within 300 m of the MOLA derived locations, and usually within tens of meters, with no adjustments to camera pointing. THEMIS VIS images appear to be systematically shifted to the southwest of their correct positions and MOC images are often kilometers off. The good SNR and minimal artifacts make the CTX images vastly more useful than the THEMIS VIS or MOC images. The bulk of the mapping was done at 1:50,000 scale on CTX images. In more complex areas, mapping at 1:24,000 proved necessary. The CTX images were usually simultaneously viewed on a second monitor using the ISIS3 qview program to display the full dynamic range of the CTX data. Where CTX data was not available, mapping was often done at 1:100,000 and most contacts are mapped as approximate.

27 CFR 9.152 - Malibu-Newton Canyon.

Code of Federal Regulations, 2010 CFR

2010-04-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Dispersion and photochemical evolution of reactive pollutants in street canyons

NASA Astrophysics Data System (ADS)

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

2013-05-01

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

Coprates Chasma

NASA Technical Reports Server (NTRS)

1998-01-01

Mars Orbiter Camera (MOC) image of a 10 km by 12 km area of Coprates Chasma (14.7 degrees S, 55.8 degrees W), a ridge with a flat upper surface in the center of Coprates Chasma, which is part of the 6000-km-long Valles Marineris. Rock layers are visible just below the ridge. The gray scale (4.8 m/pixel) MOC image was combined with a Viking Orbiter color view of the same area. The faults of a graben offset beds on the slope to the left.

Figure caption from Science Magazine

Large, Windblown Ripples

NASA Technical Reports Server (NTRS)

2003-01-01

MGS MOC Release No. MOC2-447, 9 August 2003

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the plethora of large, windblown ripples (or small dunes) among wind-sculpted sedimentary rocks in eastern Candor Chasma. Candor Chasma is one of the troughs of the Valles Marineris, a system of chasms that would stretch all the way across North America if it were on Earth. This picture is located near 7.9oS, 64.9oW. Sunlight illuminates the scene from the left/upper left.

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

NASA Astrophysics Data System (ADS)

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

2004-12-01

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

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

USGS Publications Warehouse

Billingsley, George H.; Hampton, Haydee M.

1999-01-01

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

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

NASA Astrophysics Data System (ADS)

Wang, H.; Gong, D.

2016-02-01

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

Basaltic Ring Structures as an Analog for Ring Features in Athabasca Valles, Mars

NASA Technical Reports Server (NTRS)

Jaeger, W. L.; Keszthelyi, L. P.; Burr, D. M.; Emery, J. P.; Baker, V. R.; McEwen, A. S.; Miyamoto, H.

2005-01-01

Basaltic ring structures (BRSs) are enigmatic, quasi-circular landforms in eastern Washington State that were first recognized in 1965. They remained a subject of geologic scrutiny through the 1970 s and subsequently faded from the spotlight, but recent Mars Orbiter Camera (MOC) images showing morphologically similar structures in Athabasca Valles, Mars, have sparked renewed interest in BRSs. The only known BRSs occur in the Channeled Scabland, a region where catastrophic Pleistocene floods from glacial Lake Missoula eroded into the Miocene flood basalts of the Columbia Plateau. The geologic setting of the martian ring structures (MRSs) is similar; Athabasca Valles is a young channel system that formed when catastrophic aqueous floods carved into a volcanic substrate. This study investigates the formation of terrestrial BRSs and examines the extent to which they are appropriate analogs for the MRSs in Athabasca Valles.

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

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

Francisco Vallés and the Renaissance reinterpretation of Aristotle's Meteorologica IV as a medical text.

PubMed

Martin, Craig

2002-01-01

In this paper I describe the context and goals of Francisco Vallés In IV librum Meteorologicorum commentaria (1558). Vallés' work stands as a landmark because it interprets a work of Aristotle's natural philosophy specifically for medical doctors and medical theory. Vallés' commentary is representative of new understandings of Galenic-Hippocratic medicine that emerged as a result of expanding textual knowledge. These approaches are evident in a number of sixteenth-century commentaries on Meteorologica IV; in particular the works of Pietro Pomponazzi, Lodovico Boccadiferro, Jacob Schegk, and Francesco Vimercati. Vallés' conviction that Meteorologica IV is relevant to medical knowledge depends on his understanding of Aristotle's theory of homeomerous substances and their relation to composite substances. The application of Meteorologica IV to medical topics became commonplace in the following years, and this Aristotelian book became widely known as a bridge between natural philosophy and medicine.

Westernmost Grand Canyon incision: Testing thermochronometric resolution

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

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

NASA Astrophysics Data System (ADS)

Shank, T. M.

2016-02-01

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

Lava Flows in the Grand Canyon

NASA Technical Reports Server (NTRS)

2003-01-01

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

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

USGS Publications Warehouse

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

2014-01-01

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

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

USGS Publications Warehouse

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

1998-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

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

Optimizing Street Canyon Orientation for Rajarhat Newtown, Kolkata, India

NASA Astrophysics Data System (ADS)

De, Bhaskar; Mukherjee, Mahua

2017-12-01

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

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

USGS Publications Warehouse

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

2000-01-01

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

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

USGS Publications Warehouse

Normark, William R.; Carlson, Paul R.

2003-01-01

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

Currents in monterey submarine canyon

USGS Publications Warehouse

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

2009-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2016-07-01

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

Oak Canyon Action Memo

EPA Pesticide Factsheets

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

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

USGS Publications Warehouse

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

2012-01-01

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

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

USGS Publications Warehouse

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

2016-06-10

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

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2014 CFR

2014-07-01

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

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2012 CFR

2012-07-01

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

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2011 CFR

2011-07-01

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

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2013 CFR

2013-07-01

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

Trundling Boulders

NASA Image and Video Library

2016-11-09

This picture of the rim of Eos Chasma in Valles Marineris shows active erosion of the Martian surface. Layered bedrock is exposed in a steep cliff on a spur of the canyon rim. Dark layers in this cliff are made up of large boulders up to 4 meters in diameter. The boulders are lined up along specific horizons, presumably individual lava flows, and are perched to descend down into the canyon upon the slightest disturbance. How long will the boulders remain poised to fall, and what will push them over the edge? Just as on Earth, the main factors that contribute to dry mass wasting erosion on Mars are frost heaving and thermal expansion and contraction due to changes in temperature. The temperature changes on Mars are extreme compared to Earth, because of the lack of humidity in the Martian atmosphere and the eccentricity of the Martian orbit. Each daily temperature cycle and each seasonal change from summer to winter produces a cycle of expansion and contraction that pushes the boulders gradually closer to the brink. Inevitably, the boulders fall from their precarious positions and plunge into the canyons below. Most simply slide down slope and collect just below the source layers. A few are launched along downward trajectories, travelling long distances before they settle on the slopes below. These trundling boulders left behind conspicuous tracks, up to a kilometer long. The tracks resemble dashed lines or perforations, indicating that the boulders bounced as they trundled down the slopes. The visibility of the boulder tracks suggests that this process may have taken place recently. The active Martian winds quickly erased the tracks of the rover Opportunity, for example. However, the gouges produced by trundling boulders probably go much deeper than the shallow compression of soil by the wheels of a relatively lightweight rover. The boulder tracks might persist for a much longer time span than the rover tracks for this reason. Nevertheless, the tracks of the

B-Plant Canyon Ventilation Control System Description

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

MCDANIEL, K.S.

1999-08-31

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

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

USGS Publications Warehouse

Xu, J. P.

2011-01-01

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

Red Rock Canyon National Conservation Area Transportation Feasibility Study

DOT National Transportation Integrated Search

2012-07-31

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

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

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

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

1994-12-01

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

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

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

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

1982-05-01

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

Land- and resource-use issues at the Valles Caldera

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

Intemann, P.R.

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 maximizemore » 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.« less

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

NASA Astrophysics Data System (ADS)

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

2009-04-01

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

Investigating Mars: Hebes Chasma

NASA Image and Video Library

2017-08-17

The large mesa in the center of Hebes Chasma dominates this image. The top of the mesa is at the center of the image, with the cliff faces to the top and bottom of the image. The layering of the mesa is most easily identified in the lower part of the image. The long linear depression on the northern face indicate that wind action played a large part in eroding the mesa. Hebes Chasma is an enclosed basin not connected to Valles Marineris. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 15281 Latitude: -1.13682 Longitude: 283.509 Instrument: VIS Captured: 2005-05-25 12:52 https://photojournal.jpl.nasa.gov/catalog/PIA21812

Efflorescence as a source of hydrated sulfate minerals in valley settings on Mars

NASA Astrophysics Data System (ADS)

Szynkiewicz, Anna; Borrok, David M.; Vaniman, David T.

2014-05-01

A distinctive sulfur cycle dominates many geological processes on Mars and hydrated sulfate minerals are found in numerous topographic settings with widespread occurrences on the Martian surface. However, many of the key processes controlling the hydrological transport of sulfur, including sulfur sources, climate and the depositional history that led to precipitation of these minerals, remain unclear. In this paper, we use a model for the formation of sulfate efflorescent salts (Mg-Ca-Na sulfates) in the Rio Puerco watershed of New Mexico, a terrestrial analog site from the semiarid Southwest U.S., to assess the origin and environmental conditions that may have controlled deposition of hydrated sulfates in Valles Marineris on Mars. Our terrestrial geochemical results (δS34 of -36.0 to +11.1‰) show that an ephemeral arid hydrological cycle that mobilizes sulfur present in the bedrock as sulfides, sulfate minerals, and dry/wet atmospheric deposition can lead to widespread surface accumulations of hydrated sulfate efflorescences. Repeating cycles of salt dissolution and reprecipitation appear to be major processes that migrate sulfate efflorescences to sites of surface deposition and ultimately increase the aqueous SO42- flux along the watershed (average 41,273 metric tons/yr). We suggest that similar shallow processes may explain the occurrence of hydrated sulfates detected on the scarps and valley floors of Valles Marineris on Mars. Our estimates of salt mass and distribution are in accord with studies that suggest a rather short-lived process of sulfate formation (minimum rough estimate ∼100 to 1000 years) and restriction by prevailing arid conditions on Mars.

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

USGS Publications Warehouse

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

2011-01-01

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

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

USGS Publications Warehouse

Karl, Herman A.

1980-01-01

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

Bioethics and Climate Change: A Response to Macpherson and Valles.

PubMed

Resnik, David B

2016-10-01

Two articles published in Bioethics recently have explored the ways that bioethics can contribute to the climate change debate. Cheryl Cox Macpherson argues that bioethicists can play an important role in the climate change debate by helping the public to better understand the values at stake and the trade-offs that must be made in individual and social choices, and Sean Valles claims that bioethicists can contribute to the debate by framing the issues in terms of the public health impacts of climate change. While Macpherson and Valles make valid points concerning a potential role for bioethics in the climate change debate, it is important to recognize that much more than ethical analysis and reflection will be needed to significantly impact public attitudes and government policies. © 2016 John Wiley & Sons Ltd.

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

USGS Publications Warehouse

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

2013-01-01

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

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

USGS Publications Warehouse

Hamill, John

2008-01-01

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

Wrinkle ridges in the floor material of Kasei Valles, Mars: Nature and origin

NASA Technical Reports Server (NTRS)

Watters, Thomas R.; Craddock, Robert A.

1991-01-01

Wrinkle ridges on Mars occur almost exclusively in smooth plains material referred to as ridged plains. One of the largest contiguous units of ridged plains occurs on Lunae Planum on the eastern flank of the Tharsis rise. The eastern, western, and northern margins of the ridged plains of Lunae Planum suffered extensive erosion in early Amazonian channel-forming events. The most dramatic example of erosion in early Amazonian plains is in Kasei Valles. The nature an origin of the wrinkle ridges in the floor material of Kasei Valles are discussed.

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

NASA Astrophysics Data System (ADS)

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

2016-02-01

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

Creationism in the Grand Canyon, Texas Textbooks

NASA Astrophysics Data System (ADS)

Folger, Peter

2004-01-01

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

Anomalous topography on the continental shelf around Hudson Canyon

USGS Publications Warehouse

Knebel, H.J.

1979-01-01

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

Exploring Groundwater origin for theater-headed valleys on the walls of Ius Chasma based on geomorphological analogy to the Saharan Plateaus

NASA Astrophysics Data System (ADS)

Farag, A. Z. A.; Heggy, E.; Mohamed, R.

2017-12-01

Understanding the origin and evolution of Martian fluvial landforms constrains the ambiguities associated to the variability of paleoclimatic and hydrological conditions. Despite of the significance of understanding the mechanism of formation of theater-headed valleys (THV) in Valles Mariners, where abundant distribution of seasonal liquid water flow is reported, their origin remains debatable. The original groundwater sapping hypothesis is challenged by the capability of springs to cut canyons into massive rocks and alternatively mega-floods and landslides were suggested. On Earth however, widespread THV cutting through the carbonate plateaus in the Sahara are confirmed to be of long-lasting groundwater processes based on recent isotopic, geochemical and hydrogeological evidences. Geomorphological characterizations of the THV in both the Sahara and in Valles Marineris suggest similar settings including: (1) widespread and dense occurrence along the length of escarpments, (2) low relief floors, (3) association with extensive faulting, and (4) lack of well-developed stream networks and small upstream contributing areas. The above suggest that both the Martian and the Saharan THV to be of groundwater origins. Herein, we constraint the geomorphological, lithological and textural characteristics of THV in El Diffa and El-Merir plateaus in the Eastern Sahara as a limited analog to the THV in Ius Chasma using structural and textural mapping derived from ALOS PalSAR scenes and similar settings on Mars using SHARAD, MOLA and HIRISE images. These observations are correlated with several in-situ field and laboratory measurements for hardness, granulometry and channel morphology to support the common phenomenology. Preliminary findings show that in both sets of THV, we observe a spatial confinement of boulders to the sidewalls with relatively finer grains along the channel courses, and association with large-scale hydrated sulphates along the sidewalls and channel bottoms

Numerical modelling of erosion and assimilation of sulfur-rich substrate by martian lava flows: Implications for the genesis of massive sulfide mineralization on Mars

NASA Astrophysics Data System (ADS)

Baumgartner, Raphael J.; Baratoux, David; Gaillard, Fabrice; Fiorentini, Marco L.

2017-11-01

Mantle-derived volcanic rocks on Mars display physical and chemical commonalities with mafic-ultramafic ferropicrite and komatiite volcanism on the Earth. Terrestrial komatiites are common hosts of massive sulfide mineralization enriched in siderophile-chalcophile precious metals (i.e., Ni, Cu, and the platinum-group elements). These deposits correspond to the batch segregation and accumulation of immiscible sulfide liquids as a consequence of mechanical/thermo-mechanical erosion and assimilation of sulfur-rich bedrock during the turbulent flow of high-temperature and low-viscosity komatiite lava flows. This study adopts this mineralization model and presents numerical simulations of erosion and assimilation of sulfide- and sulfate-rich sedimentary substrates during the dynamic emplacement of (channelled) mafic-ultramafic lava flows on Mars. For sedimentary substrates containing adequate sulfide proportions (e.g., 1 wt% S), our simulations suggest that sulfide supersaturation in low-temperature (< 1350 °C) flows could be attained at < 200 km distance, but may be postponed in high-temperature lavas flows (> 1400 °C). The precious-metals tenor in the derived immiscible sulfide liquids may be significantly upgraded as a result of their prolonged equilibration with large volumes of silicate melts along flow conduits. The influence of sulfate assimilation on sulfide supersaturation in martian lava flows is addressed by simulations of melt-gas equilibration in the Csbnd Hsbnd Osbnd S fluid system. However, prolonged sulfide segregation and deposit genesis by means of sulfate assimilation appears to be limited by lava oxidation and the release of sulfur-rich gas. The identification of massive sulfide endowments on Mars is not possible from remote sensing data. Yet the results of this study aid to define regions for the potential occurrence of such mineral systems, which may be the large canyon systems Noctis Labyrinthus and Valles Marineris, or the Hesperian channel

Wrinkle Ridges and Pit Craters

NASA Image and Video Library

2016-10-19

Tectonic stresses highly modified this area of Ganges Catena, north of Valles Marineris. The long, skinny ridges (called "wrinkle ridges") are evidence of compressional stresses in Mars' crust that created a crack (fault) where one side was pushed on top of the other side, also known as a thrust fault. As shown by cross-cutting relationships, however, extensional stresses have more recently pulled the crust of Mars apart in this region. (HiRISE imaged this area in 2-by-2 binning mode, so a pixel represents a 50 x 50 square centimeter.) http://photojournal.jpl.nasa.gov/catalog/PIA21112

Extracting Compositional Variation from THEMIS Data for Features with Large Topography on Mars Via Atmospheric Equalization

NASA Technical Reports Server (NTRS)

Anderson, F. S.; Drake, J. S.; Hamilton, V. E.

2005-01-01

We have developed a means of equalizing the atmospheric signature in Mars Odyssey Thermal Emission Imaging System (THEMIS) infrared data over regions with large topography such as the Valles Marineris (VM). This equalization allows for the analysis of compositional variations in regions that previously have been difficult to study because of the large differences in atmospheric path length that result from large changes in surface elevation. Specifically, our motivation for this study is to examine deposits that are small at the scales observable by the Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor, but which are more readily resolved with THEMIS.

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

USGS Publications Warehouse

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

2013-01-01

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

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

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

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

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

NASA Astrophysics Data System (ADS)

Lapotre, Mathieu; Lamb, Michael

2013-04-01

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

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

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

NASA Astrophysics Data System (ADS)

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

2017-08-01

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

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

USGS Publications Warehouse

Hamill, John F.

2009-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2013-04-01

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

Compressive strain in Lunae Planum-shortening across wrinkle ridges

NASA Technical Reports Server (NTRS)

Plescia, J. B.

1991-01-01

Wrinkle ridges have long been considered to be structural or structurally controlled features. Most, but not all, recent studies have converged on a model in which wrinkle ridges are structural features formed under compressive stress; the deformation being accommodated by faulting and folding. Given that wrinkle ridges are compressive tectonic features, an analysis of the associated shortening and strain provides important quantitative information about local and regional deformation. Lunae Planum is dominated by north-south trending ridges extending from Kasei Valles in the north to Valles Marineris in the south. To quantify the morphometric character, a photoclinometric study was undertaken for ridges on Lunae Planum using the Davis and Soderblom. More than 25 ridges were examined between long. 57 and 80 deg, lat. 5 to 25 deg N. For each ridge, several profiles were obtained along its length. Ridge width, total relief, and elevation offset were measured for each ridge. Analyses are given.

Regional economic impacts of Grand Canyon river runners.

PubMed

Hjerpe, Evan E; Kim, Yeon-Su

2007-10-01

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

The Jurassic section along McElmo Canyon in southwestern Colorado

USGS Publications Warehouse

O'Sullivan, Robert B.

1997-01-01

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

Noctis Labyrinthus

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 26 April 2002) The Science This image shows a portion of Noctis Labyrinthus, a large valley system at the western end of the Valles Marineris canyon system. Noctis Labyrinthus is notable for its unusual pattern of intersecting valleys, which give the region a maze-like appearance when viewed from above. The walls of these valleys are very high (5 km) and quite steep, with slopes approaching 35o. Dust covers most of this region, leading to its rather uniform appearance. At the tops of the ridgelines, small dark streaks can be observed trailing downslope; these streaks suggest that the sediments covering this area occasionally become unstable and slide. Ridges of resistant material also can be observed in the highest terrains. In the lower half of the image, a small linear feature appears to cut across the generally NE/SW-trending slopes. This feature is not continuous, indicating that geologic activity has disrupted it since its formation. The northeastern termination of the feature is on a mesa, where it is joined by a less pronounced but similar feature that trends NE/SW. These small features may have originated in several ways: they may be ridges formed by compression, they may be small fault scarps, or they may represent the edges of ancient lava flows that have been disrupted by the formation of the valley system. The Story The smoothly sculpted surface in this close-up image belies the bizarre and twisted Martian landscape of which it is a part (seen at a larger scale in the context image). Labyrinths have long been in the human imagination, and it's no wonder that this area conjured up for early viewers all of the legends of antiquity, of a land where a Minotaur hides and a conquering hero needs a spool of thread to guide him through an inner maze. As writer Jorge Luis Borges might say, this Martian region is a real-life example of a geological 'garden of forking paths,' a dangerous-seeming place where 'the paths of the labyrinth converge.' Noctis

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

USGS Publications Warehouse

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

2010-01-01

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

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2011 CFR

2011-07-01

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

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2014 CFR

2014-07-01

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

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2013 CFR

2013-07-01

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

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2010 CFR

2010-07-01

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

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2012 CFR

2012-07-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

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

PubMed

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

2018-05-15

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

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

36 CFR 7.92 - Bighorn Canyon National Recreation Area.

Code of Federal Regulations, 2010 CFR

2010-07-01

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

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

NASA Astrophysics Data System (ADS)

Lamb, Michael P.; Fonstad, Mark A.

2010-07-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

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

NASA Astrophysics Data System (ADS)

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

2011-12-01

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

Complex Sulfate Deposits in Coprates Chasma

NASA Technical Reports Server (NTRS)

2008-01-01

This image of layered sulfate-containing deposits in the Coprates Chasma region of Mars was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 1827UTC (1:27 p.m. EST) on December 12, 2006 near 10.2 degrees south latitude, 68.8 degrees west longitude. The image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 40 meters (132 feet) across. The image is about 11 kilometers (6.8 miles) wide at its narrowest point.

Coprates Chasma forms part of the backbone of the Valles Marineris canyon system. It extends approximately east-west for roughly 966 kilometers (600 miles), and is one of the larger chasmata in the Valles Marineris system.

The top panel in the montage above shows the location of the CRISM image on a mosaic taken by the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS). The CRISM data covers an area centered on a knob near the chasma's northern wall.

The center left image, an infrared false color image, shows the knob's layered morphology. The center right image unveils the mineralogical signatures of some of those layers, with yellow representing monohydrated sulfates (sulfates with one water molecule incorporated into each molecule of the mineral) and purple representing polyhydrated sulfates (sulfates with multiple waters per mineral molecule).

The lower two images are renderings of data draped over topography with 3 times vertical exaggeration. These images provide a view of the topography and reveal how the sulfate deposits relate to that topography. Darker polyhydrated sulfates (purple) lie along the knob's western flank. Brighter, monohydrated sulfates (yellow) appear to be superimposed on polyhydrated sulfate deposits in the southwest corner of the image. These coarsely banded deposits continue along the southeast side of the knob.

There are two possible explanations for the compositional banding of these sulfates. The first is deposition of

No Mystery! Water Carved the Outflow Channels on Mars

NASA Astrophysics Data System (ADS)

Coleman, N.

2002-12-01

floodwaters dammed by ice and debris, analogous to the scabland flooding of eastern Washington. The water sources were probably ice-covered impoundments in ancestral Valles Marineris canyons. Subice volcanism was a possible source of heat to create liquid water. The former existence of transient water bodies near the surface can help to calibrate models of a volcanic-hydrologic climax during the Hesperian.

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

USGS Publications Warehouse

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

1984-01-01

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

H-Canyon Recovery Crawler

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

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

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

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

Code of Federal Regulations, 2011 CFR

2011-07-01

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

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

Code of Federal Regulations, 2010 CFR

2010-07-01

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

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

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

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

NASA Astrophysics Data System (ADS)

Lietzke, Björn; Vogt, Roland

2013-08-01

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

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

PubMed Central

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

2015-01-01

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

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

USGS Publications Warehouse

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

2014-01-01

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

Standardized methods for Grand Canyon fisheries research 2015

USGS Publications Warehouse

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

2013-01-01

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

75 FR 34476 - Glen Canyon Dam Adaptive Management Work Group

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-17

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

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

USGS Publications Warehouse

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

2006-01-01

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

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

USGS Publications Warehouse

Thomas, Blakemore E.

2003-01-01

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

Are amphitheater headed canyons indicative of a particular formative process?

NASA Astrophysics Data System (ADS)

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

2012-12-01

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

Effects of building roof greening on air quality in street canyons

NASA Astrophysics Data System (ADS)

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

2012-12-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

3D View of Grand Canyon, Arizona

NASA Technical Reports Server (NTRS)

2000-01-01

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

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

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

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

NASA Astrophysics Data System (ADS)

Gromke, Christof; Ruck, Bodo

2012-07-01

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

Gas geochemistry of the Valles caldera region, New Mexico and comparisons with gases at Yellowstone, Long Valley and other geothermal systems

USGS Publications Warehouse

Goff, F.; Janik, C.J.

2002-01-01

Noncondensible gases from hot springs, fumaroles, and deep wells within the Valles caldera geothermal system (210-300??C) consist of roughly 98.5 mo1% CO2, 0.5 mol% H2S, and 1 mol% other components. 3He/4He ratios indicate a deep magmatic source (R/Ra up to 6) whereas ??13C-CO2 values (-3 to -5???) do not discriminate between a mantle/magmatic source and a source from subjacent, hydrothermally altered Paleozoic carbonate rocks. Regional gases from sites within a 50-km radius beyond Valles caldera are relatively enriched in CO2 and He, but depleted in H2S compared to Valles gases. Regional gases have R/Ra values ???1.2 due to more interaction with the crust and/or less contribution from the mantle. Carbon sources for regional CO2 are varied. During 1982-1998, repeat analyses of gases from intracaldera sites at Sulphur Springs showed relatively constant CH4, H2, and H2S contents. The only exception was gas from Footbath Spring (1987-1993), which experienced increases in these three components during drilling and testing of scientific wells VC-2a and VC-2b. Present-day Valles gases contain substantially less N2 than fluid inclusion gases trapped in deep, early-stage, post-caldera vein minerals. This suggests that the long-lived Valles hydrothermal system (ca. 1 Myr) has depleted subsurface Paleozoic sedimentary rocks of nitrogen. When compared with gases from many other geothermal systems, Valles caldera gases are relatively enriched in He but depleted in CH4, N2 and Ar. In this respect, Valles gases resemble end-member hydrothermal and magmatic gases discharged at hot spots (Galapagos, Kilauea, and Yellowstone). Published by Elsevier Science B.V.

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

NASA Astrophysics Data System (ADS)

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

2016-11-01

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

Fourmile Canyon Fire Findings

Treesearch

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

2012-01-01

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

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

NASA Astrophysics Data System (ADS)

Mitchell, N. C.

2004-12-01

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

Related magma-ice interactions: Possible origins of chasmata, chaos, and surface materials in Xanthe, Margaritifer, Meridiani Terrae, Mars

USGS Publications Warehouse

Chapman, M.G.; Tanaka, K.L.

2002-01-01

We examine here the close spatial and temporal associations among several unique features of Xanthe and Margaritifer Terrae, specifically the Valles Marineris troughs or chasmata and their interior deposits, chaotic terrain, the circum-Chryse outflow channels, and the subdued cratered material that covers Xanthe, Margaritifer, and Meridiani Terrae. Though previous hypotheses have attempted to explain the origin of individual features or subsets of these, we suggest that they may all be related. All of these features taken together present a consistent scenario that includes the processes of sub-ice volcanism and other magma/ice interactions, results of intrusive events during Late Noachian to Early Amazonian times. ?? 2002 Elsevier Science (USA).

Geology of Chryse Planitia

NASA Technical Reports Server (NTRS)

Greeley, R.; Theilig, E.; Guest, J. E.; Carr, M. H.; Masursky, H.; Cutts, J. A.

1977-01-01

Chryse Planitia, the site of the first successful landing on Mars by Viking 1, is an asymmetrical basin, centered at 45 deg W and 24 deg N, about 2000 km northeast of Valles Marineris. High-resolution Viking orbiter images show Chryse Planitia to be much more complex than had been suspected from Mariner 9 images. On the basis of a study of the Viking pictures it is concluded that the geological history of Chryse Planitia involves a complex sequence of impact cratering, mantling by extensive deposits of unknown origin, redistribution of mantling and crater materials by erosion and deposition with concurrent eruptions of flood-type basalts, and aeolian activity.

Landslide in Coprates

NASA Technical Reports Server (NTRS)

2004-01-01

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows part of a large landslide complex off the north wall of Coprates Chasma in the Valles Marineris trough complex. The wall of Coprates Chasma occupies much of the upper and middle portions of the image; the landslide lobes are on the trough floor in the bottom half of the image. Large boulders the size of houses can be seen on these landslide surfaces. This image is located near 13.9 S, 56.7 W. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.

Bits and Pieces

NASA Technical Reports Server (NTRS)

2006-01-01

19 August 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the contact between an area of light-toned rock and an expanse of darker-toned materials on the floor of Coprates Chasma. Remnants -- bits and pieces -- of the light-toned material are scattered throughout the scene, indicating that this material once covered everything in this area. Coprates is one of several chasms that comprise the giant Valles Marineris trough system.

Location near: 13.2oS, 61.8oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

The Coming and Going of Ice

NASA Image and Video Library

2015-12-10

Like Earth's water table, Mars has an ice table. Sometimes, the ice table coincides with the ground's surface as it does here. The knobby, pitted terrain is caused when ice is deposited and then sublimates over and over again. This geologic process is called "accrescence" and "decrescence" and also occurs on Neptune's moon Triton and on Pluto, though in the outer Solar System the ice is not water ice. Other evidence for ice here includes the rope-like, curved flow feature that resembles glacial flow. Solis Planum -- a huge mound south of Valles Marineris -- is the location of this image. http://photojournal.jpl.nasa.gov/catalog/PIA20208

78 FR 21415 - Glen Canyon Dam Adaptive Management Work Group

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-10

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

Contrasting cratonal provenances for upper Cretaceous Valle Group quartzite clasts, Baja California

USGS Publications Warehouse

Kimbrough, D.L.; Abbott, G.; Smith, D.P.; Mahoney, J.B.; Moore, Thomas E.; Gehrels, G.E.; Girty, G.H.; Cooper, John D.

2006-01-01

Late Cretaceous Valle Group forearcbasin deposits on the Vizcaino Peninsula of Baja California Sur are dominated by firstcycle arc-derived volcanic-plutonic detritus derived from the adjacent Peninsular Ranges batholith. Craton-derived quartzite clasts are a minor but ubiquitous component in Valle Group conglomerates. The source of these clasts has implications for tectonic reconstructions and sediment-dispersal paths along the paleo-North American margin. Three strongly contrasting types of quartzite are recognized based on petrology and detrital zircon U-Pb geochronology. The first type is ultramature quartz arenite with well-rounded, highly spherical zircon grains. Detrital zircon ages from this type are nearly all >1.8 Ga with age distributions that closely match the distinctive Middle-Late Ordovician Peace River arch detrital signature of the Cordilleran margin. This type has been previously recognized from prebatholithic rocks in northeast Baja California (San Felipe quartzite). A second quartzite type is subarkosic sandstone with strong affinity to southwestern North America; important features of the age spectra are ~1.0-1.2 Ga, 1.42 and 1.66 Ga peaks representing cratonal basement, 500-300 Ma grains interpreted as recycled Appalachian-derived grains, and 284- 232 Ma zircon potentially derived from the Early Permian-Middle Triassic east Mexico arc. This quartzite type could have been carried to the continental margin during Jurassic time as outboard equivalents of Colorado Plateau eolianites. The third quartzite type is quartz pebble conglomerate with significant ~900- 1400 Ma and ~450-650 Ma zircon components, as well as mid- and late Paleozoic grains. The source of this type of quartzite is more problematic but could match either upper Paleozoic strata in the Oaxaca terrane of southern Mexico or a southwestern North America source. The similarity of detrital 98 zircon spectra in all three Valle Group quartzite types to rocks of the adjacent Cordilleran

Mars Global Surveyor Approach Image

NASA Image and Video Library

1997-07-04

This image is the first view of Mars taken by the Mars Global Surveyor Orbiter Camera (MOC). It was acquired the afternoon of July 2, 1997 when the MGS spacecraft was 17.2 million kilometers (10.7 million miles) and 72 days from encounter. At this distance, the MOC's resolution is about 64 km per picture element, and the 6800 km (4200 mile) diameter planet is 105 pixels across. The observation was designed to show the Mars Pathfinder landing site at 19.4 N, 33.1 W approximately 48 hours prior to landing. The image shows the north polar cap of Mars at the top of the image, the dark feature Acidalia Planitia in the center with the brighter Chryse plain immediately beneath it, and the highland areas along the Martian equator including the canyons of the Valles Marineris (which are bright in this image owing to atmospheric dust). The dark features Terra Meridiani and Terra Sabaea can be seen at the 4 o`clock position, and the south polar hood (atmospheric fog and hazes) can be seen at the bottom of the image. Launched on November 7, 1996, Mars Global Surveyor will enter Mars orbit on Thursday, September 11 shortly after 6:00 PM PDT. After Mars Orbit Insertion, the spacecraft will use atmospheric drag to reduce the size of its orbit, achieving a circular orbit only 400 km (248 mi) above the surface in early March 1998, when mapping operations will begin. http://photojournal.jpl.nasa.gov/catalog/PIA00606

The Hebrus Valles Exploration Zone: Access to the Martian Surface and Subsurface

NASA Astrophysics Data System (ADS)

Davila, A.; Fairén, A. G.; Rodríguez, A. P.; Schulze-Makuch, D.; Rask, J.; Zavaleta, J.

2015-10-01

The Hebrus Valles EZ represents a diverse setting with multiple geological contacts and layers, possible remnant water ice and protected subsurface environments, which could be critical for the establishment of long-term human settlements.

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

NASA Astrophysics Data System (ADS)

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

2016-02-01

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

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

PubMed

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

2017-08-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

Mapping wilderness character in Sequoia and Kings Canyon National Parks

Treesearch

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

2014-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-07-01

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

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

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-08

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

Turbulent Transfer Between Street Canyons and the Overlying Atmospheric Boundary Layer

NASA Astrophysics Data System (ADS)

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

2011-12-01

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

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

NASA Astrophysics Data System (ADS)

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

2012-04-01

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

Small-scale turbidity currents in a big submarine canyon

USGS Publications Warehouse

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

2013-01-01

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

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

NASA Astrophysics Data System (ADS)

Sumner, E.; Paull, C. K.

2017-12-01

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

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

NASA Astrophysics Data System (ADS)

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

2014-06-01

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

BLANCO MOUNTAIN AND BLACK CANYON ROADLESS AREAS, CALIFORNIA.

USGS Publications Warehouse

Diggles, Michael F.; Rains, Richard L.

1984-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2003-07-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-03-01

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

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

Treesearch

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

2002-01-01

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

Canyons and Mesas of Aureum Chaos

NASA Image and Video Library

2002-06-26

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

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

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

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

1982-08-01

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

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

NASA Astrophysics Data System (ADS)

Gaudin, M.; Umr 5805; Ifremer Team

2003-04-01

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

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

USGS Publications Warehouse

Grams, Paul E.

2013-01-01

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

Impact of building configuration on air quality in street canyon

NASA Astrophysics Data System (ADS)

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

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