False Pass (M7139) (Miocene of the United States)

Also known as USGS M7139

Where: Aleutians East County, Alaska (55.0° N, 162.8° W: paleocoordinates 56.0° N, 161.2° 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 Flase 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 37398: 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 indet. Linnaeus 1758 clam
 Arcida - Glycymerididae
"Glycymeris grewingki" = Glycymeris (Axinola) septentrionalis
"Glycymeris grewingki" = Glycymeris (Axinola) septentrionalis Middendorf 1849 clam
 Pectinida - Pectinoidae
"Chlamys (Swiftopecten) cosibensis" = Chlamys (Chlamys) cosibensis
"Chlamys (Swiftopecten) cosibensis" = Chlamys (Chlamys) cosibensis Yokoyama 1911 scallop
Subspecies: Chlamys (Swiftopecten) cosibensis cosibensis
 Carditida - Carditidae
 Pholadida - Myidae
Mya (Arenomya) elegans softshell clam
 Cardiida - Mactridae
"Spisula (Mactromeris) albaria" = Mactromeris albaria, Spisula sp.
"Spisula (Mactromeris) albaria" = Mactromeris albaria Conrad 1848 clam
Spisula sp. Gray 1837 clam
 Cardiida - Ungulinidae
"Felaniella parilis" = Diplodonta parilis
"Felaniella parilis" = Diplodonta parilis Conrad 1848 clam
 Cardiida - Veneridae
Saxidomus sp. Conrad 1837 venus clam
 Cardiida - Tellinidae
"Peronidia aff. lutea" = Tellina (Megangulus) lutea, Macoma sp.
"Peronidia aff. lutea" = Tellina (Megangulus) lutea Gray 1828 tellin clam
Subspecies: Peronidia aff. P. lutea alternidentata
Macoma sp. Leach 1819 tellin clam
 Cardiida - Cardiidae
Clinocardium sp. Keen 1936 cockle
 Pandorida - Pandoridae
 Neogastropoda - Buccinidae
Buccinum sp. Linnaeus 1758 true whelk
 Neogastropoda - Conidae
Oenopota sp. Mörch 1852 cone shell
 Naticoidea - Naticidae
"Natica (Cryptonatica) clausa" = Cryptonatica affinis
"Natica (Cryptonatica) clausa" = Cryptonatica affinis Gmelin 1791 moon snail
 Tonnoidea - Ranellidae
Fusitriton oregonensis Redfield 1846 triton shell
  - Neptuneidae
Neptunea sp. Röding 1798 snail
Neptunea (Neptunea) lyrata Gmelin 1791 snail
Subspecies: Neptunea (Neptunea) lyrata altispira