22 May 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, windblown ripples on the floors of channels of the Apsus Vallis system. The fluid responsible for forming the valleys is unknown; it might have been water. No primary landforms, other than the channels themselves, have been preserved in a way that would indicate the nature of the fluid that carved the valleys. Apsus Vallis is located just west of the Elysium volcanic region; the area in the picture is located near 35.5°N, 225.6°W. The image covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.