You are now approaching a bizarre landscape characterized by clay hills, hoodoos, and a colorful maze of gullies. Such areas are often called "badlands." Badlands most often develop in semiarid climates where impervious clay or shale rocks alternate with layers of sandstone. These areas contain little vegetation, making it hard for the ground to soak up the brief, but heavy rainfall associated with isolated thunderstorms. The variety of features here show the result of erosion carving both the hard and soft rock layers, some of which are nearly horizontal while others dip at steep angles. The different colors result from minerals and weathering of the rocks.