Perepelkin (Martian crater)

Much of the crater is covered with a mantle that is believed to be ice-rich and to have fallen from the atmosphere when the climate was different. In one of the images below mantle can be seen; also some places when the mantle has disappeared, channels are visible.

Researchers have noticed a smooth mantle covering much of Mars.^[2] Some parts are eroded revealing rough surfaces while others possess layers. It's generally accepted that mantle is ice-rich dust that fell from the sky as snow and ice-coated dust grains during a different climate ^[3] One evidence of its ice-rich nature is the presence of gullies which form when some of the ice melts.^[4][5][6] Only a few hours of flow can result in erosion .^[7] In higher latitudes, such as around Milankovic Crater, the mantle is thicker and may contain rounded shapes called scallops .^[8] These are thought to be caused by the sublimation of ice in the mantle. Several models have been advanced to explain them; some include a small amount of melting at times.^{[9][10][11][12]}

• 
  Perepelkin Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).
• 
  Channels and mantle, as seen by CTX camera (on Mars Reconnaissance Orbiter). Channels are exposed where the mantle has disappeared.

• List of craters on Mars