The Medusae Fossae Formation (MFF) on Mars is an intensely eroded deposit north of the cratered highlands. It is widely thought that MFF materials were emplaced through ignimbrite eruptions. Recent geologic mapping of western MFF identified outliers of MFF materials well beyond the previously mapped western extent for the deposit, including outliers close to Gale crater. We report counts of impact craters on the MFF units that have implications for our understanding of the general history of MFF and the uppermost layered materials on the Gale crater mound.
Zimbelman, James R. and Scheidt, Stephen P. 2012. Hesperian Age for Western Medusae Fossae Formation, Mars. <i>Science<i>, 336(6089): 1683 doi:10.1126/science.1221094