Eocene Fossils
The Eocene is the second epoch of the Cenozoic Era starting 55 million years ago and lasted 15 million years. Grasses began to to a major part of planetary flora and the interaction of grazers and grass had impact on evolution during the Cenozoic.
Green River Formation, Colorado and Wyoming
The Green River formation is exposed over large tracts of western Colorado and Wyoming. Primarily shale, the deposits were laid down in fresh water lakes.
