Recurring slope lineae (RSL) are seasonal flows on warm slopes, and are especially common in central and eastern Valles Marineris. This image covers a large area full of interesting features, but the enhanced color closeup highlight some of the RSL .

Here, the RSL are active on east-facing slopes, extending from bouldery terrain and terminating on fans. Perhaps the fans themselves built up over time from the seasonal flows. Part of the fans with abundant RSL are dark, while the downhill portion of the fans are bright. The role of water in RSL activity is a matter of active debate.

Written by: Alfred McEwen (audio: Tre Gibbs)  (4 May 2017)

More info and image formats at http://hirise.lpl.arizona.edu/ESP_049955_1665

Image: NASA/JPL/University of Arizona