False Pass (M7149) (Miocene of the United States)

Also known as USGS M7149

Where: Aleutians East County, Alaska (55.0° N, 164.6° W: paleocoordinates 56.0° N, 163.1° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Tachilni Formation, Tortonian (11.6 - 7.2 Ma)

• Formation crops out continuously from the coast west of Cape Tachilni from Morzhovoi Bay to False Pass and possibly of Deer Island. Thickness of the Tachilni Fm is not known because its base is not exposed, but is estimated to be as much as 460 m thick, although not more than 250 m and any outcrop. Disconformably overlies volcaniclastic Belkofski Fm, and is unconformably overlain by Pliocene-Holocene volacanic flows and breccia.

• bed-level stratigraphic resolution

Environment/lithology: coastal; fine-grained, medium, brown, gray sandstone

• Composed mostly of dark brown to light greenish-gray, fine- to coarse-grained sandstone, abundant similarly colored siltstone, with some pebble conglomerate and black shale....mainly a fine- to medium-grained sandstone.

Size class: macrofossils

Reposited in the CAS, USNM

Collection methods: quarrying,

• Also collections at University of Alaska (UA), Fairbanks, Alaska

Primary reference: L. Marincovich. 1983. Molluscan paleontology, paleoecology, and North Pacific correlations of the Miocene Tachilni Formation, Alaska Peninsula, Alaska. Bulletin of American Paleontology 84(317):1-155 [A. Miller/A. Hendy/A. Hendy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 37406: authorized by Austin Hendy, entered by Austin Hendy on 14.03.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

• Exhaustive for molluscan taxa
Bivalvia
 Pectinida - Pectinoidae
 Carditida - Carditidae
Cyclocardia sp. Conrad 1867 clam
 Pholadida - Myidae
Mya (Arenomya) elegans softshell clam
Mya (Mya) truncata Linnaeus 1758 softshell clam
 Cardiida - Mactridae
Spisula sp. Gray 1837 clam
 Cardiida - Tellinidae
"Peronidia (Peronidia) aff. lutea" = Tellina (Megangulus) lutea
"Peronidia (Peronidia) aff. lutea" = Tellina (Megangulus) lutea Gray 1828 tellin clam
Subspecies: Peronidia aff. P. lutea alternidentata
 Cardiida - Cardiidae
Clinocardium sp. Keen 1936 cockle
"Clinocardium meekianum" = Clinocardium (Clinocardium) meekianum Gabb 1866 cockle