Sediment Ponds in Tithonium Chasma

This survey of the canyon floor of Tithonium Chasma in Valles Marineris reveals terrain of two distinct ages. The slopes and hilltops here are made up of rough rocky outcrop that was sculpted by impact craters of all sizes. In contrast, the valley floors are filled with light toned, smooth materials with far fewer large craters. At HiRISE resolution, we can see that the "smooth" materials are in fact littered with boulders and small impact craters, so they cannot have been emplaced very recently. However, the absence of larger craters tells us that the smooth materials are much younger than the ancient rocky outcrops of the canyon floor. The smooth materials appear to be sediments that were deposited possibly by the wind, long after the canyon was formed. The sediments filled in the low lying spots in the canyon floor, leaving a landscape that resembles lakes and ponds but is made up of dust and sand instead of water. https://photojournal.jpl.nasa.gov/catalog/PIA26328