False Pass (M7258) (Miocene of the United States)

Also known as USGS M7258

Where: Aleutians East County, Alaska (55.0° N, 163.2° W: paleocoordinates 56.0° N, 161.6° W)

• coordinate stated in text

• 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 37410: authorized by Austin Hendy, entered by Austin Hendy on 14.03.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

• Exhaustive for molluscan taxa
Gastropoda
 Neogastropoda - Buccinidae
Neptunea sp. Röding 1798 true whelk
Bivalvia
 Cardiida - Mactridae
"Spisula (Mactromeris) polynyma" = Mactromeris polynyma
"Spisula (Mactromeris) polynyma" = Mactromeris polynyma Stimpson 1860 clam
 Cardiida - Cardiidae
"Clinocardium ex gr. pristinum" = Clinocardium (Clinocardium) pristinum
"Clinocardium ex gr. pristinum" = Clinocardium (Clinocardium) pristinum Keen 1954 cockle
 Cardiida - Tellinidae
Macoma sp. Leach 1819 tellin clam
 Mytilida - Crenellidae
Musculus (Musculus) niger Gray 1824 mussel