Dark Light
North of Ganges Chasma lies Orson Welles Crater, whose floor contains broken up blocks we call chaotic terrain and which is the source for the major outflow channel Shalbatana Vallis.

Between Orson Welles and Ganges Chasma is a region where materials subsided and collapsed over underground cavities that had once held aquifers. This image shows an elongated collapse pit. There is evidence that the pit was once filled with water as the groundwater erupted to the surface. A closer view shows fine sedimentary layers exposed by erosion.


Image: NASA/JPL/University of Arizona https://www.uahirise.org/hipod/ESP_070818_1780
Related Posts

Secondary Craters

This image of a southern mid-latitude crater was intended to investigate the lineated material on the crater floor. At the higher resolution of HiRISE, the image reveals a landscape peppered by small impact craters.

Soffen Crater Floor

Dr. Gerald A. Soffen (February 7, 1926 — November 22, 2000) was a project scientist for the NASA’s Viking program of Mars landers.
Old Features and New

Old Features and New

This image covers a portion of a typical impact crater in Terra Sirenum at about 40 degrees south latitude on Mars.