These multi-elevation gullies have formed on the northern slope of a multi-lobed ejecta impact crater in Hesperia Planum in the ancient highlands of Mars. The higher elevation gullies have formed at or just below the crater rim with wide alcoves and some tributaries have eroded into underlying bedrock.

Aprons at the end of the gullies are cut by fractures. Some fractures have cut across certain fans while other fans have buried these fractures. The latter fans are likely younger than the fractured aprons. Gullies formed on the lower slopes to the west have largely cut into resistant bedrock layers. The fans of some of these gullies have also been cut by transverse fractures.

The presence of these fractures and the curvy ridges downslope of the fans may be related to subsurface ice or perhaps glacial processes. The fractures are reminiscent of crevasses, which are formed by compressive forces, and the curvy ridges at the fan termini may suggest moraine-like features which mark the extent of a glacier with debris that the glacier was transporting.

Written by: Ginny Gulick  (25 June 2024)