Desert Plains

This paper contains a general review of the six types of plains that are ordinarily found in deserts, considering them especially from the viewpoint of origin. The list includes pediments, bajadas (compound fans), lake bottoms (including playas), dip slopes, graded river flood plains, and aggraded river flood plains. Of these the first two are particularly characteristic of deserts and are far more widespread than the others. On account of the confusion which prevails in recent geologic literature regarding these dominant types, the author has outlined the characteristics of pediments and bajadas more fully and explained the means of distinguishing them from each other. Pediments are the normal results of erosion under stable conditions in the desert. The formation of Bajadas is induced by diastrophic movements, climatic change, and other interruptions of the normal cycle. Combinations of pediments and bajadas are rather common and require more care for their identification.