The face of this cliff preserves a chronology of geologic events and clues about ancient animals and habitat. Halfway up the cliff face, a series of vertical spiral shapes first called devil's corkscrews, or Daemonelix, by local ranchers are sandstone burrows of ancient beavers, Palaeocastor. Their spacing and number suggest these animals lived in communities similar to those of modern prairie dogs. The top of each burrow marks the ground level when these beavers lived, and fossilized plant roots associated with the burrows suggest abundant vegetation, including grassland, near wide shallow streams. The sandstone forming the cliff face was deposited over thousands of years as sediment filling an ancient Miocene valley, and the present topography was later sculpted by erosion of the Niobrara River. Each corkscrew burrow opens at the bottom into a nesting chamber tilted upward to prevent the accumulation of water.