The 40-kilometer diameter unnamed crater in this image from HiRISE is located west of Lyot Crater and north of Deuteronilus Mensae in the Northern Plains of Mars. NASA/JPL/University of Arizona
As seen in the subimage, gully systems in the central structure have eroded underlying layers (undercutting) that are less resistant to erosion than the surface rock of the central structure. Previous channelized water flows likely transported the eroded sediments toward the southeast and deposited them forming the expansive debris aprons.
written by: Ginny Gulick