The dark dunes in the western Medusae Fossae formation provide some evidence of having a local origin.

This image shows no large dunes, but many of the dark sand patches cover slopes up to discrete layers. It is possible that the sand is eroding out from those layers, but slopes can also act as sand traps.

Written by: HiRISE Science Team (audio: Tre Gibbs)   (4 March 2015)

More info and image formats at http://hirise.lpl.arizona.edu/ESP_039240_1730

Image: NASA/JPL/University of Arizona