Search

The presence of buried glacial ice and putative extinct rock glaciers in Mars' equatorial regions has implications for understanding its climate history and sensitivity to changes in insolation and has significant implications for past global redistribution of the water ice cryosphere. We quantify the morphology of rock glacier- "like" features on the northern slopes of Aeolis Mons (known also as Mount Sharp) within Gale crater and use this information to evaluate a possible rock glacier origin for these forms. Detailed morphometric evaluation of cross and long profiles of these lobate features, which exhibit higher slopes at their heads, lower slopes at their distal edge, and a convex upward cross-sectional profile and oversteepened sides, resembles active terrestrial rock glaciers. However, the absence of a chevron wrinkle pattern and sublimation features could indicate extensive aeolian reworking and the lack of deflation could indicate a higher rock to ice mixture. The lack of cratering surfaces relative to the cratered surfaces that they overly could indicate a younger age and are possibly indistinguishable in age from the capping units of Mount Sharp, which may have once been more laterally extensive and may have been the source of these mass wasting forms. [ABSTRACT FROM AUTHOR]

Abstract: Characterization of dune morphology has historically been based on relationships between dune forms and wind regimes with dune height shown to be sensitive to atmospheric boundary layer depth, sand availability and sediment properties. While these parameters have been used in numerical simulations to model the occurrences of some types of dunes, they cannot alone explain the great diversity in form and size seen on Earth and on other solar system bodies. Here we present results from our studies of dune formation in the Badain Jaran Desert in western China, where Earth''s tallest dunes occur. We measured the variability of the dune morphology in this desert on the basis of LANDSAT ETM+ data, and we detected the bedrock landforms beneath the aeolian sands by applying gravity methods. Wind records from stations at the periphery of the desert and SRTM topographical data were examined also to augment the interpretation. Our studies demonstrate that in addition to average wind parameters, dune height is highly sensitive to local geology, subsurface characteristics, and topography, and interactions between changing climate conditions and aeolian and fluvial processes. These additional factors need to be considered in the interpretation and simulation of dunes on Earth. We anticipate that analysis of anomalous dune heights like those seen in the Badain Jaran may also provide critical information on subsurface characteristics and environmental conditions on Earth and on other planetary bodies. [Copyright &y& Elsevier]

Understanding the subsurface hydrology, or ground water elevation, of arid environments like large dune forming deserts, is critical to sustaining habitable zones during times of rapid climate change. The tallest dunes and largest sand sea in the solar system is located on Earth, in China's Badain Jaran Desert. The Badain Jaran Desert provides a unique study area because it has been inhabited by human populations since prehistoric times, and provides a unique opportunity to utilize both geologic and archaeological evidence for indicators of Quaternary climate change over the past 5,000 years. We hypothesize that the decrease in water table elevation reflected in modern interdune lakes is a result of Quaternary climate change, transforming the region from wetlands to an arid dune complex. Although this area has a rich archaeological record, limited studies have been conducted to understand the modern water table elevation and its change through recent Earth history. Using satellite imagery and geospatial processing and analyzing tools such as ArcGIS and Google Earth, the modern ground water elevation was traced within the dune field and compared to ancient lake core sediment samples. The samples were radio-carbon dated to compare the rate of change in ground water elevation over the past 5,000 years. Utilizing the archaeological record within the study area, we compared the change in human populations within the region to the change in water resources over time and found a relationship between population decrease and a decrease in ground water elevation within the Quaternary. [ABSTRACT FROM AUTHOR]