A sulcus (or sulci, plural) is defined as “subparallel furrows and ridges.” This is a purely descriptive term for landforms that could have a variety of origins.

At this location is appears to be a graben (which is a fault-bounded valley) on a large scale, and locally (such as in this image) became a vent region for lava flows.

Written by: Alfred McEwen (audio: Tre Gibbs)   (3 June 2015)

More info and image formats at http://hirise.lpl.arizona.edu/ESP_040661_1890

Image: NASA/JPL/University of Arizona