The Makah Formation is a geologic formation in Washington (state). It was deposited during the late Paleogene period between the late Eocene and early Oligocene epoches, and preserves marine fossils dating to the early Oligocene. It outcrops at the northwestern edge of the Olympic Peninsula. It appears to have been deposited in a deepwater environment, and the presence of glendonites suggests that water temperatures ranged near freezing at certain sites of deposition.