As gullies form on slopes, sediment can become deposited to form lobe-shaped fans. Gullies can form with flowing water, but don’t have to: sometimes they can be formed by the dry flow of sand and dust grains. This HiRISE image shows several seemingly active gullies and their associated fans.
These particular gullies have many fine channels that are resolved nicely with a high resolution image .
Written by: HiRISE Science Team (audio: Tre Gibbs) (28 January 2015)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_038931_1355
Image: NASA/JPL/University of Arizona