Zeugens Wind abrasion turns a desert a desert area which has a surface layer of hard rock underlain by a layer of soft rock into a ridge and furrow landscape. The ridges are called zeugens which may be as high as 30 meters. Ultimately the are undercut and gradually worn away. Yardangs Bands of hard and soft rocks which lie parallel to the prevailing winds in a desert region are turned into another type of ridge and furrow landscape by wind and abrasion. Yardangs are very common in the central Asian desert and in the Atacama desert.
Some depressions produced by wind deflation reach down to water bearing rocks.
A swamp or an oasis then develops. It has salt marshes and the sand excavated from it forms a zone of dunes on the leeside Fault produced depressions The formation of a depression may first be caused by faulting. The soft rocks thus exposed are excavated by wind action.