1. Dune Fields, Namibian Coastal Desert
The arid coastal plain that forms the Namib Desert extends the entire length of the Atlantic coast of South West Africa, a total of more than 800 kilometers (500 miles). Its width varies between 40 and 140 kilometers (25 and 90 miles). The intricate pattern of large sand dunes is caused mainly by dry westerly winds cooled by the offshore Benguela current. Some of the dunes are extremely large, exceeding 300 meters (1000 feet). Running diagonally downward from the upper right corner is a dune-free tongue of alluvial gravel known as the Sossus Vlei. This is formed by occasional flash floods draining from the barren, rocky hills on the right of the picture.
STS-41D, August-September 1984. Picture #14-45-035.