Crater Dunes

This VIS image shows a large sand sheet with surface dune forms as well as smaller sand dunes within an unnamed crater in Noachis Terra. These dunes are composed of basaltic sand that has collected in the bottom of the crater. The topographic depression of the crater forms a sand trap that prevents the sand from escaping. Dune fields are common in the bottoms of craters on Mars and appear as dark splotches that often lean up against the downwind walls of the craters. Dunes are useful for studying both the geology and meteorology of Mars. The sand forms by erosion of larger rocks, but it is unclear when and where this erosion took place on Mars or how such large volumes of sand could be formed. The dunes also indicate the local wind directions by their morphology. Orbit Number: 92028 Latitude: -48.9171 Longitude: 34.0952 Instrument: VIS Captured: 2022-09-12 21:08 https://photojournal.jpl.nasa.gov/catalog/PIA25742