Fish Fossils
Fish Fossils

The Green River Formation is 33 to 55-million-year old geologic formation that collects sedimentation in a group of intermountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah. Within the Green River Formation of southwest Wyoming in the area known as fossil lake, two distinct zones of very fine-grained line muds are particularly noted for preserving a variety of complete and detailed fossils. These layers are on Eocene Lagerstätte, a rare place where conditions were right for a rich accumulation of undisturbed fossils. The most productive zone- callked the split fish layer – consist of a series of laminated lime muds about 6 ft. thick which contains abundant fish and other fossils. 


The Green River Formation is 33 to 55-million-year old geologic formation that collects sedimentation in a group of intermountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah. Within the Green River Formation of southwest Wyoming in the area known as fossil lake, two distinct zones of very fine-grained line muds are particularly noted for preserving a variety of complete and detailed fossils. These layers are on Eocene Lagerstätte, a rare place where conditions were right for a rich accumulation of undisturbed fossils. The most productive zone- callked the split fish layer – consist of a series of laminated lime muds about 6 ft. thick which contains abundant fish and other fossils.