An impact crater near the south pole characterized by pristine-appearing secondary crater chains is partly covered with more than a kilometer of polar layered terrain deposits continuous with the main polar deposit. The observed relationships strongly suggest that the crater formed near the edge of the cap in Amazonian time, was buried by polar cap advance, and that some retreat occurred. These data appear to indicate that the south polar cap has been active in the geologically recent past. ¿ 2001 American Geophysical Union