The Camas Valley Formation is an early Eocene geologic unit in the southern Oregon Coast Range within the southern Tyee Basin, formed as the sea advanced across the region and preserving Paleogene fossils. It consists chiefly of dark-gray mudstone and siltstone with minor sandstone interbeds, indicating deposition in relatively low-energy marine conditions. In some areas it also contains calcareous concretions and fossil-bearing beds. The formation conformably overlies older strata of the Umpqua Group and is overlain by the Tyee Formation. Extending across the region and commonly more than 1,500 feet thick, it preserves an important record of early Eocene marine environments in Oregon.