The Green River Formation represents one of the largest documented accumulations of sedimentary rock in the world and dates back to the Early Eocene, 50 million years ago. It covers an area of more than 25,000 square miles (65,000 square kilometers) and averages about 2,000 feet (600 meters) in thickness. It covers portions of three states; Wyoming, Colorado and Utah in the United States.

There were three major lakes formed by geological events that uplifted the Rocky Mountains in earlier times, the Fossil Lake, Lake Gosiute and Lake Uinta. The climate was much different than the desert climate of today. It was similar to the present subtropical climate of the Gulf Coast and the southern Atlantic areas of the United States.

A vast majority in private and public collections consists of Green River fossil fish from the Fossil Lake area. These one of a kind fossil fish have been commercially mined since the late 1800’s. There are a wide variety of wonderful fossils to be found in the Green River Formation. The fossil flora of the Green River Formation is extensive and contains all sizes of specimens ranging from microscopic pollen, leaves, branches, seeds, flowers and the world’s best fossilized palm frond leaves. The size of palm frond leaves can be up to 7 feet (2 meters). The Green River fossils include reptiles such as, snakes, lizards, turtles and 16-foot (5 meters) crocodiles. The fish range from minnow size to over 5-foot (1.5 meters) gar fish. More than 20 species of freshwater fish have been identified. Many of these fish are recognizable as ancestors of today’s species.

Reoccurring unique conditions came together to result in some of the best-preserved fossils ever discovered. Green River fish and stingrays are often perfectly preserved. Many of the fish retain their entire skeletons, their teeth, scales and skin as well. The Green River Formation can add to anyone’s home or office décor with some of the most aesthetic fossils frozen in time by Mother Nature herself.