Recent small craters discovered by the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter expose buried ice in the middle latitudes of Mars. This ice is a record of past climate change. Not stable today, it was deposited during a period of different obliquity, or tilt, of the planet's axis.
This image is one product from HiRISE observation ESP_011337_2360.
Photo credit: NASA/JPL-Caltech/Univ. of Arizona
Notes: This crater was formed in 2008. In the larger images of the area taken by HiRISE (see the link above), the crater appears as a tiny white splotch. In the image shown above, the other tiny craters are presumably secondary craters caused by ejecta from the primary (large) impact crater.