The European Space Agency's Mars Express -- an orbiter studying the interior, subsurface, and surface of the planet Mars -- has recently returned new images that suggest craters found throughout the planet's landscape were once filled with water and sediments, long since drained, and left a barren planetary desert with just hints to its wet past.
The images, taken on January 15, are of a region north of an ancient riverbed called Tagus Valles and east of Tinto Valles and Palos crater
Yardangs, formations carved from abrasive forces shaping the sediments, tell the ancient story of the deposits left during a flood event believed to have once covered the entire region.
Over time, slow erosion from retreating water has removed some of the sediment, leaving the patterns of stronger blocks behind, seen in the form of channels (lower center), fluidized debris around craters, (bottom right), and blocks of eroded sediments (top left). Additional geologic activity, possibly volcanoes, may have deposited the fine dusting of dark material which can be seen in the top left.