The Writing is on the Wall

These U-shaped ridges along this crater's interior wall provide clues to an ice-rich past. The curved, scalloped ridges, called moraines, are made up of rocks that the glacier collected as it moved downslope. Even after the ice disappears, the glacial moraines remain, marking the furthest extent (or end) of the glacier. The parallel linear ridges on the wall may mark past levels of the glacier. Although glaciers move slowly, ice is a very powerful way to modify the surface of a planet.