In geological circles, a wedge of sediment left behind by flowing water is know as as an alluvial fan. This image, captured by NASA's Mars Reconnaissance Orbiter, reveals two large impact craters that will be used to age such features and reveal how water shaped the Red Planet.
Image by NASA/JPL-Caltech/Univ. of Arizona
The images were acquired by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Because the craters neatly reveal the structure of the alluvial fans, scientists will be able to use them to age the layers of sediment -- like the rings on a tree. In turn, it should tell us more about how water helped sculpt the surface of Mars.