This image shows part of several long, lobe-shaped deposits of sediment in the Coprates Chasma region of Valles Marineris. These deposits formed when rocks in very steep terrain became unstable and collapsed, forming a landslide.

The landslide flowed downhill and created these lobe-shaped deposits. The deposits have ridges along their perimeter called levees or flank ridges. Flank ridges are observed within landslide deposits on the Earth and are generally believed to form through progressive downhill movement of the landslide over a long period of time. In other words, the middle part of the landslide continues to flow downhill after the sides of the landslide have stopped moving.

A closer look at the sides of the flank ridges reveals that they are composed of many different layers of sediment, from fine-grained, sandy layers to coarse, bouldery layers. This stratification suggests that the landslide was formed by multiple collapses of rock, rather than though one catastrophic collapse. Thus, the flank ridges and stratification within them indicate that this area experienced a period of numerous overlapping slope collapses and downhill movement of landslides.

Written by: Chris Okubo  (19 March 2026)

This is a stereo pair with ESP_090400_1660.