Mangala Fossae

Today's VIS image shows an unnamed crater in Terra Sirenum dissected by the graben of Mangala Fossae. This impact crater was filled almost to the crater rim with new materials, and then the tectonic forces which created Mangala Fossae cracked that surface into many pieces. Mangala Fossae are long linear depressions called a graben and were formed by extension of the crust and faulting. When large amounts of pressure or tension are applied to rocks on timescales that are fast enough that the rock cannot respond by deforming, the rock breaks along faults. In the case of a graben, two parallel faults are formed by extension of the crust and the rock in between the faults drops downward into the space created by the extension. Mangala Fossae is 828 km long (514 miles).