UW 490 (Oligocene of the United States)

Also known as Slip Point

Where: Clallam County, Washington (48.3° N, 122.3° W: paleocoordinates 48.0° N, 113.3° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Clallam Formation, Chattian (28.1 - 23.0 Ma)

• GENERAL STRATIGRAPHY: The Clallam Formation is a predominantly marine sandstone with minor conglomerate and siltstone exposed along the Strait of Juan de Fuca in northwestern Washington. Marine molluscs occur throughout the 600 to 800 m thick formation but are especially abundant in the lowermost 240 m. Pillarian Stage age, a provincial time stratigraphic unit of late early Miocene age. Revised to Chattian following more recent work [Hendy, 7/2016].

• bed-level stratigraphic resolution

Environment/lithology: offshore; lithified, silty sandstone

• All Clallam Formation assemblages represent inner sublittoral depths (less than about 100 m). Qualitative analysis of these assemblages indicates a gradual shallowing during deposition of the formation. The highest strata in the formation contain coal and are presumably non-marine.
• Sandstone with minor conglomerate and siltstone.

Size class: macrofossils

Preservation: mold/impression

Reposited in the UWBM

Collection methods: surface (float), surface (in situ),

• REPOSITORY: Burke Museum, University of Washington.

Primary reference: W.O. Addicott. 1976. Molluscan paleontology of the lower Miocene Clallam Formation, northwestern Washington. United States Geological Survey Professional Paper 976:1-44 [A. Miller/A. Hendy/A. Hendy]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 37584: authorized by Austin Hendy, entered by Austin Hendy on 17.03.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

• Only molluscan taxa listed.
Gastropoda
 Neogastropoda - Fasciolariidae
Priscofusus slipensis Addicott 1976 snail
 Neogastropoda - Turridae
"Megasurcula cf. wynoocheensis" = Surculites (Megasurcula)
"Megasurcula cf. wynoocheensis" = Surculites (Megasurcula) turrid
 Tonnoidea - Cassidae
Semicassis pyshtensis Addicott 1976 snail