Many Small Interesting Ridges in Erythraea Fossa

These light-toned ridges are found in a large fracture located east of Holden Crater and form a curious box-like pattern.

A hair-line fracture runs along the axis of each ridge line. The overall pattern spans several hundred meters across and individual ridges are several meters wide. Scientists are not sure how they formed yet, but some possible explanations suggest that mineral-rich ground water flowed out of the hairline fractures and deposited minerals at or near the surface as the water evaporated.

In addition, these minerals may have formed a cement along the fractures, making these patterns more resistant to subsequent erosion by wind or other processes. The resulting cemented ridges then stand high above the surrounding plains.

HiRISE is one of six instruments on NASA's Mars Reconnaissance Orbiter. The University of Arizona, Tucson, operates the orbiter's HiRISE camera, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for the NASA Science Mission Directorate, Washington.