Coober Pedy provides an example of slope development in an arid area. There are two plains separated by slopes which are the subject of this paper. The upper plain is duricrusted and this hard layer has an important protecting effect on the underlying rock. The slopes are gullied and water erosion was important in the formation of both the lower plain and the slopes. Both plains are covered by lag deposits of gibbers indicating considerable wind action. Landslides and desert gilgai are of minor importance. Many slopes take the form of “J” curves, with an upper straight section and a lower concave slope. There is a general parallelism of slopes, but there is variation in detail. Debris is nowhere more than a veneer, and accumulations of debris are not responsible for any slope elements. Slope development takes place largely by parallel retreat.