White River Formation

The White River Formation is a Paleogene geologic formation spread across parts of the northern Great Plains and central Rocky Mountains, with exposures in northeastern Colorado, western Nebraska, the Badlands of western South Dakota, and southeastern Wyoming. Its rocks preserve fossils from the Eocene and Oligocene epochs of the Cenozoic Era. It is especially significant for holding North America’s most complete vertebrate record from the transition between the Late Eocene, or Priabonian, and Early Oligocene, or Rupelian, making it an essential reference for understanding prehistoric life during that period.

Wyoming · United States