Crater Gullies

Today's VIS image shows part of an unnamed crater in Aonia Terra. At the top of the image numerous gullies dissect the crater rim. These channels are called gullies due to being on a steep slope rather than a flat river plain. In some images it is possible to see a boundary layer between the upper incised gully and a lower deposition region. The boundary marks a change in slope, the steep upper portion supports fast moving fluid that carves into the rim, eroding materials. The change to a flatter slope causes the fluid to slow down and as it slows the materials carried by the fluid are deposited. Sand dunes cover part of the crater floor.