The Green River Formation in Wyoming is one of the most famous and important Eocene (50-45 million years old) sites in the world. It provides a glimpse of the daily life surrounding the great Fossil Lake. From the prolific fossil fish deposits, the Green River Formation is also famous for it's insect, mammal, and even plant fossils! The formation exposes itself from southern Wyoming and into Utah and Colorado and shows us how life was more temperate at that time, often 60-70 degrees Fahrenheit. An exciting and dramatic difference to the climate in modern day Wyoming.