Fretted Terrains and Ground Deformation

This observation shows an excellent example of what is called “fretted terrain,” termed so because of the eroded appearance of the surface.

What causes this kind of terrain? One explanation is the sublimation of subsurface ground ice that goes directly from a solid state to a gaseous one. When that occurs, the material is removed and the ground can collapse in a jumbled pattern. The curving ridges and lineations could be indicative of slow movement of the ice-rich material, perhaps in a way that has similarities to rock glaciers on Earth.

Written by: HIRISE Science Team (audio by Tre Gibbs)   (16 October 2013)

More info and image formats at

Image: NASA/JPL/University of Arizona