This image from the High Resolution Imaging Science Experiment (HiRISE) on
NASA's Mars Reconnaissance Orbiter shows an exposure of layered rock that
exhibits a type of fracturing—called columnar jointing—that
results when cooling lava contracts.
The observation is cited in a report, "Discovery of Columnar Jointing on Mars,"
in the February 2009 issue of the journal Geology. The authors propose
that flooding by water was likely what caused a quick cooling of lava to
result in this jointing.
The image, taken Oct. 31, 2007, shows a portion of an unnamed crater 16
kilometers (10 miles) in diameter and centered at 21.52 degrees north
latitude, 184.35 degrees north longitude. Shown here is a section about
one kilometer (0.6 mile) wide from the image catalogued by the HiRISE team
as PSP_005917_2020. The column-forming fractures resemble textures common on
Earth in locations such as the Colombia River Basalt Group and in the
Colorado Plateau.
NASA's Jet Propulsion Laboratory, a division of the California Institute
of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for
NASA's Science Mission Directorate, Washington. Lockheed Martin Space
Systems, Denver, is the prime contractor for the project and built the
spacecraft. The High Resolution Imaging Science Experiment is operated by
the University of Arizona, Tucson, and the instrument was built by Ball
Aerospace & Technologies Corp., Boulder, Colo.