<p>A Volcano of Mud or Lava? 
</p><p>This image shows a hill with a central crater. Such features have been interpreted as both mud volcanoes (really a sedimentary structure) and as actual volcanoes (the erupting lava kind). They occur on the floor of Valles Marineris below a closed topographic contour that could have held a lake, and the compaction of wet sediments may have created mud volcanoes. 
</p><p>The fracture pattern of the bright flow unit surrounding the hill resembles mud cracks. However, there have also been observations from the CRISM instrument interpreted as high-temperature minerals, suggesting actual volcanism, although not necessarily at this location. Fine layers in the hill are consistent with either volcanism or mud flows.
</p><p>Either way, this activity is relatively recent in geologic time and may mark habitable subsurface environments.
</p><p>NASA/JPL/University of Arizona
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2018-05-18 15:21
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