M7154 - Bear Lake Fm, Ukolnoi Island (Miocene of the United States)

Also known as 77AM24

Where: Alaska (55.2° N, 161.6° W: paleocoordinates 56.7° N, 159.0° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Bear Lake Formation, Middle Miocene (16.0 - 11.6 Ma)

• STRATIGRAPHIC RELATIONS: From Bear Lake Fm, which is presumed to overlie the Stepovak Fm (Paleogene), though the contact is not exposed. AGE: Middle Miocene. 15-16 Mas, or earliest Middle Miocene based on the presence of Turritella (Hataiella) sagai. This is the greatest known age for any Bear Lake outcrop. An overlying andesitic flow has been radiometrically dated at 10.4 Ma. STRATIGRAPHIC POSITION: Unknown position within formation.

• bed-level stratigraphic resolution

Environment/lithology: transition zone or lower shoreface; lithified, coarse-grained sandstone

• ENVIRONMENT: Within the inner part of the inner shelf zone, at approximately 25-35 m; cool-temperate thermal conditions.
• SPECIFIC LITHOLOGY: Not stated in text, though said to be coarse and nearshoe, assumed to be sandstone; conglomerates known from formation. LITHIFICATION: Assumed to be lithified given comments about preservation and age.

Size class: macrofossils

Reposited in the LACM, USNM

Collection methods: quarrying,

• COLLECTOR: L. Marincovich, Jr (1977). REPOSITORY: USGS (Menlo Park), LACM, USNM

Primary reference: L. Marincovich. 1988. Recognition of an earliest Middle Miocene warm-water event in a southestern Alaskan molluscan fauna. Saito-Ho-on Kai Special Publication 1:1-24 [A. Hendy/A. Hendy/P. Wagner]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 67917: authorized by Austin Hendy, entered by Austin Hendy on 16.12.2006

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Exhaustive for gastropoda, bivalvia, and scaphopoda. NOMENCLATURE: Authoritative publication with modern nomenclature, and use of species and subgenus names. Identified by L. Marincovich.
Gastropoda
 Cerithioidea - Turritellidae
Turritella (Hataiella) sagai Kotaka 1951 turret shell
 Sorbeoconcha - Naticidae
"Natica (Cryptonatica) clausa" = Cryptonatica affinis
"Natica (Cryptonatica) clausa" = Cryptonatica affinis Gmelin 1791 moon snail
 Sorbeoconcha - Ranellidae
Fusitriton oregonensis Redfield 1846 triton shell
Bivalvia
 Thraciida - Thraciidae
Thracia sp. Blainville 1824 clam
 Cardiida - Veneridae
? Pitar sp. Römer 1857 venus clam
 Cardiida - Tellinidae
Macoma sp. Leach 1819 tellin clam
 Lucinida - Lucinidae
Lucinoma acutilineata Conrad 1849 clam