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T-TRA_000836_1740_RED_CandorChasma_01.jpgCandor Chasma57 visiteCandor Chasma is one of several large troughs that make up Valles Marineris, the largest canyon system in the Solar System. Much of Candor Chasma is filled with layered deposits, like those shown in this HiRISE sub-image. Layers only 1-2 meters thick can be resolved by HiRISE and provide details on the processes that emplaced and modified these sediments. The layered deposits could be volcanic, lacustrine, or eolian sediments that filled in some portions of the trough of Valles Marineris. The variations in brightness of the layers could represent compositional differences in the layers or the thickness of overlying debris, such as sand or dust. This area was targeted because minerals rich in sulfur were detected here by the OMEGA instrument on Mars Express. By using HiRISE images to look at specific geologic units that correspond to these locations of sulfate, it may be possible to determine the origin of the sediments, particularly those that contain the sulfates. The paucity of impact craters on the layered deposits suggests either a young age for the sediments or erosion has removed much of the upper layers to reveal a fresher-looking surface. Dark dunes and ripples indicate that wind has been, and still may be, moving debris across the sedimentary deposits.
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T-TRA_000862_1710_RED_CandorChasma_01.jpgCandor Chasma56 visiteThis HiRISE sub-image shows the steep slopes along wallrock in the eastern edge of West Candor Chasma. In general, the rocks in the upper part of the canyons are interpreted to be lava flows that cover the plains surrounding Valles Marineris, whereas the deeper material along the walls could be either more lava flows or megaregolith that resulted from numerous impact craters that disrupted the Martian surface during the first billion years after formation of the planet. Resistant material is visible in portions of the sub-image and HiRISE is able to resolve 1-2 meter size boulders shedding out of these resistant wallrock units. The bright and dark lineations seen in the right of the sub-image follow the slope of the wallrock (downslope is towards the top of the sub-image) and likely represent bright dust and dark sand that are sliding downslope. The large number of small impact craters visible along the slopes indicates that there isn't a large amount of material moving downslope recently because these craters would have been destroyed or buried.
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