of the Huntingdon Formation lie disconformably on parts of the Cretaceous Nanaimo Group. Deposition of the Chuckanut continued as convergence of the Crescent Terrane (Olympic Peninsula) initiated strike-slip motion on the Straight Creek Fault (48 Ma), displacing much of the original formation to the north. Continued deposition across the Straight Creek Fault formed the Raging River and Puget Group formations east of Seattle; the former is partly marine, indicating it was probably a large delta, and locating the Eocene coast line. Deposition is believed to have largely ended in the late Eocene (around 42 Ma?) when regional uplift diverted the rivers supplying the sediments, but some deposition may have continued, supplied from local sources. estimated a total thickness of , which would make the Chuckanut Formation one of the thickest nonmarine sedimentary sequences in North America. But more recent work suggest that, at least in parts, it may be only thick. Fossils Various plant and animal fossils have been found in the Chuckanut Formation. A fossil turtle shell was recovered from the formation at Clark Point in 1960. The specimen was held in the private collection of the finders until 1981 when it was examined at Western Washington University and identified as an indeterminate member of the Testudinoidea superfamily. Reexamination of the fossil in 2000 showed the specimen belongs to the Trionychidae family of soft shelled turtles. Eocene fossil trackways are found in the Chuckanut Formation, composed of birds, mammals, and some turtle tracks. It is thought that the Chuckanut Formation shoreline was of riverine environments combined with a large scale "bedding plane" of material deposition. Four deposition or track sites are known. See also Geology of the Pacific Northwest Fossils References Bibliography External links Washington Geology: Paleogeography and Paleontology of the Chuckanut Formation Washington Geology: On the Trail of Washington Dinosaurs Geologic formations of Washington (state) Geology of British Columbia Eocene Series of North America Sandstone formations Fluvial deposits Ichnofossiliferous formations