Layered beds of sediment, in Schiaparelli Crater on Mars, are clearly defined in this image returned by Mars Global Surveyor. The visible area is only 1.5 km across. Whether the layers were deposited as a result of water or wind action is not yet known. The dark material is sand; forming a dunefield.
Such images are exciting to planetary geologists because they indicate that erosion and deposition processes similar to those on Earth have occurred on Mars in its past. They are providing more evidence that liquid water existed on the surface of Mars at some point in its history.
