One of thousands of new images released on September 2 from the University of Arizona’s HiRISE project, this amazingly detailed image shows the dramatic effects of erosion on the steep sides of Hale Crater on Mars.

Whether or not these channels were caused by liquid water or a dry process is still under investigation.

It’s possible that water ice, just beneath the sands, had melted at some point and liquid water ran down the slopes for a brief time, cutting into the hillside and carrying material down with it until it evaporated into the arid Martian air.

Or the gullies could be the result of the soil itself, devoid of any moisture at all, losing its hold on the steep crater sides and sliding downhill like a dry mudslide, moving as a liquid but without water.

Read more about this image, and see the full version here.

Image: NASA/JPL/University of Arizona