Boulder Patterns

This image of a crater floor at high southern latitude reveals many boulders ranging from 1 to 10 meters in diameter. The boulders are not distributed randomly or uniformly but are often arranged in linear or circular patterns.

Some of these patterns resemble the polygons often seen at high latitudes on Mars, which form from seasonal expansion and contraction of ground ice. Over many years, these processes might move boulders, concentrating then around the margins of polygons. If so, then the earlier polygons are no longer apparent at this location, but the boulder patterns persist.

The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. (The original image scale is 50.2 centimeters [19.8 inches] per pixel [with 2 x 2 binning]; objects on the order of 151 centimeters [59.4 inches] across are resolved.) North is up.

The University of Arizona, in Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.