These are the subdued purples of Circle Cliffs. The Circle Cliffs structure is a classic example of a breached anticline that has been carved by the powerful forces of erosion, after the uplift of the Colorado Plateau sometime within the last 20 million years. Even in this desert climate, water is the erosional agent most responsible for the carving of the landscape.
The pull of gravity, in the form of rock falls or rock creep plays a major role in the shaping of the cliff lines. Wind is a minor agent of erosion here. The landforms are a result of different responses of various rock layers to the forces of erosion.
The Circle Cliffs Uplift, which is a large doubly plunging anticline, the core of which is eroded into a large kidney-shaped physiographic basin completely surrounded by imposing vertical cliffs of Wingate Sandstone.
Hard sandstone layers, like the red Wingate and the white Navajo Sandstones, form cliffs. Softer shale layers, like the Chinle Formation, form slopes, and low hills. Its central portion is marked by a long partially wooded topographic depression. The barren slopes found in many areas are due in part to the presence of bentonitic clays in the shale which make an inhospitable environment for plants.