Where: Lewis County, Washington (46.4° N, 122.9° W: paleocoordinates 47.3° N, 109.4° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Cowlitz Formation, Bartonian (41.3 - 38.0 Ma)

• Cowlitz Formation in its type area spans upper P12 to P14 foram zones. Calcareous nannoplankton most precisely age this unit, placing the Cowlitz fauna in nannoplankton zones NP16 and NP17 (Martini, 1971) and upper CP14 (Oklada and Bukry, 1980), which correlates to the late middle Eocene (40-43 Ma) age (Berggren et al., 1992). Molluscan biostratigraphy suggests a "Tejon" stage age or "Cowlitz-Coaldeo" molluscan stage = Middle Eocene. Collection is assigned to the Bartonian=late Middle Eocene. Tuff bed in unit 3 of the Cowlitz Formation dated to 38.9± 0.1 Ma (39Ar/40Ar) (Irving et al.,1996) and three 39Ar/40Ar age dates of 38.64±0.40 (south Abernathy Mtn.), 37.44±0.45 (west Bebe Mtn.), and 36.85 ± 0.46 Ma (east Bebe Mtn.) from the overlying Grays River volcanics bracket the upper age of the formation.

• group of beds-level stratigraphic resolution

Environment/lithology: offshore; lithified, bioturbated, glauconitic mudstone

Size class: macrofossils

Collected by Walter J. Eyerdam in 1956; reposited in the PRI

Primary reference: K. V. W. Palmer. 1961. A new nautiloid, Eutrephoceras eyerdami, new species from the Cowlitz Formation, upper Eocene, of Washington. Journal of Paleontology 35:532-534 [M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 180457: authorized by Matthew Clapham, entered by Matthew Clapham on 18.07.2016, edited by Mark Uhen

Creative Commons license: CC BY (attribution)