Layered Deposits in Terby Crater

Terby Crater is a large (approximately 165 kilometer), Noachian-aged crater located on the northern rim of the Hellas impact basin.

Terby hosts a very impressive sequence of predominantly light-toned layered deposits, up to 2.5 kilometers thick that are banked along its northern rim and extend toward the center of the crater.

The full image shows this stack of layered rocks as they are exposed westward facing scarp. The layered sequence consists of many beds that are repetitive, relatively horizontal and laterally continuous on a kilometer scale. Many beds are strongly jointed and fractured and exhibit evidence of small-scale wind scour.

The light-toned layers are typically at least partially covered with dark mantling material that obscures the layers as well as debris and numerous, meter-scale boulders that have cascaded down slope. The processes responsible for formation of these layers remain a mystery, but could include deposition in water, by the wind, or even volcanic activity.

Written by: John Grant   (3 February 2010)

This is a stereo pair with PSP_002572_1520 .

More info and image formats at

Image: NASA/JPL/University of Arizona