Alluvial Fans in Kasei Vallis

Originating on the margin of Lunae Planum, the Kasei Vallis complex contains two main channels that run east-west across Tempe Terra and empty into Chryse Planitia. The formation of Kasei Vallis is still being studied and several theories exist. It is thought that volcanic subsurfaceing heating in the Tharsis/Lunae Planum region resulted in a release of water, which carved the channels and produced the landforms seen within the channels. One theory is that this was a one-time catastrophic event, another theory speculates that several flooding events occurred over a long time period. Others have proposed that some of the landforms (especially scour marks and teardropshaped 'islands') are the result of glacial flow rather thanliquid flow. Teardrop shaped islands are common in terrestrial rivers, where the water is eroding material in the channel. A glacial feature called a drumlin has the exact same shape, but is formed by deposition beneath continental glaciers.
At the top portion of this VIS image, the steep bank wall has shed material forming alluvial fans. Notice how the material covers the terracing (leftside) and reachs almost half way across the main channel.