This image is cited in a February 2009 paper, âDiscovery of Columnar Jointing on Mars.â
We report on the discovery of columnar jointing in Marte Valles, Mars. These columnar lavas were discovered in the wall of a pristine, 16-km-diameter impact crater and exhibit the features of terrestrial columnar basalts. There are discontinuous outcrops along the entire crater wall, suggesting that the columnar rocks covered a surface area of at least 200 sq. km, assuming that the rocks obliterated
by the impact event were similarly jointed. We also see columns in the walls of other fresh craters in the nearby volcanic plains of Elysium PlanitiaâAmazonis Planitia, which include Marte Vallis, and in a well-preserved crater in northeast Hellas.
Other HiRISE team papers are available here. (11 February 2009)
More info and image formats at http://hirise.lpl.arizona.edu/PSP_005917_2020
Image: NASA/JPL/University of Arizona