Dark Light
This closeup of a HiRISE image covers a region in the Eridania Basin that shows interesting inverted ridges (white arrows).

The ridges display a dendritic, or branched, pattern and may have once been connected to a larger channel (black arrows). One possible way these ridges formed is when smaller valleys filled in with sediments. These sediments became cemented and lithified which made them stronger than their surroundings.

Over time, erosion removed the surrounding terrain but the lithified sediments in the valleys are stronger so they have remained and now appear higher (or inverted) than their surroundings.


Image: NASA/JPL/University of Arizona https://www.uahirise.org/hipod/ESP_038949_1485
Related Posts

Elongated Dunes

These lovely linear dunes at Meroe Patera identified in Context Camera images that have developed in a sand starved region of the dune field, elongating from behind a cliff.

Dunes and Bedrock

Sometimes, we acquire an image for the simple reason of getting either more coverage of an area, and/or to complete a mosaic of a particular spot.

River of Sand

A dominant driver of surface processes on Mars today is aeolian (wind) activity. In many cases, sediment from this activity is trapped in low-lying areas, such as craters.