layered rock that exhibits fracturing
This image shows an exposure of layered rock that exhibits a type of fracturing -- called columnar jointing -- that results when cooling lava contracts. Image credit: NASA/JPL-Caltech/University of Arizona
› Full image and caption
Images from NASA's Mars Reconnaissance Orbiter show a type of rock fracturing that here on Earth is caused by rapid cooling of lava.

For the full story, go to the release from the U.S. Geological Survey at .