White River Formation

The White River Formation is a geologic formation of the Paleogene Period, in the northern Great Plains and central Rocky Mountains, within the United States.

It has been found in northeastern Colorado, Dawes County in western Nebraska, Badlands of western South Dakota, and Douglas area of southeastern Wyoming.

Fossil record
The geologic formation preserves fossils dating back to the Eocene and Oligocene Epochs of the Paleogene Period, during the Cenozoic Era. It contains the most complete Late Eocene−Priabonian and Early Oligocene−Rupelian vertebrate record in North America.