Sample Detail of
Sample: Sample No. 77AM22 -- USGS No. Cenozoic loc. M7152
Locality: Field No. 77AM22
Description: Shoreline exposure on south shore of Ukolnoi Island, about 120 meters north and 240 meters west of the southeast corner of Section 29, T. 57 S., R. 81 W., Port Moller (A-5) quadrangle; latitude 55o 12.5' N, longitude 161o 35.8' W; Alaska Peninsula, southwestern Alaska. Collected by L. Marincovich, Jr. and H. McLean, 1977: field locality 77AM22; equivalent to LACMIP locality 11011.
Location: Alaska Quadrangle: Port Moller A-5
Township&Range: T57S R81W Section: 120 m N, 240 m W of SE cor. Sec. 29
Lat.: 55o12.5 ' Long.: 161o35.8 '
Reference
Title: An occurrence of Turritella (Hataiella) sagai in Alaska: Implications for the age of the Bear Lake Formation ,  1986
Abstract. The gastropod Turritella (Hataiella) sagai Kotaka, 1951, previously known only from Miocene faunas of Japan, occurs in the Bear Lake Formation of the Alaska Peninsula in southwestern Alaska, U.S.A. Planktonic-microfossil and radiometric dates available for some of the Japanese occurrences indicate an age-range for this species of about 15-16 Ma, within the earliest middle Miocene. The presence of T. (H.) sagai provides the first reliable evidence for an age as great as earliest middle Miocene for strata in the Bear Lake Formation.
Report by: Louie Marincovich , Jr. , Tomoki Kase
Age: Middle Miocene (earliest Middle Miocene)
Formation: Bear Lake Formation
Occurrence(s)
No. Group Name Qty Notes
1 Snails Turritella (Hataiella) sagai Kotaka, 1951

Title: Miocene mollusks from the part of the Bear Lake Formation on Ukonoi Island, Alaska Peninsula, Alaska ,  1988
Abstract: Fossiliferous strata of the Bear Lake Formation crop out on Ukolnoi Island, Alaska Peninsula, southwestern Alaska. The molluscan fauna has an age of 15-16 Ma, or earliest middle Miocene, which is the greatest known age for any Bear Lake outcrop. A similar age is suggested by mollusks for an additional outcrop on an unnamed peninsula to the northeast of Cape Aliaksin on the adjacent Alaska Peninsula mainland. The latter outcrop is the only one known where mollusk-bearing Bear Lake strata are inferred to be in contact with mollusk-bearing strata of the Paleogene Stepovak Formation. The co-occurrence of some molluscan species on Ukonoi Island and at Cape Aliaksin, plus a radiometric age of 10.4 + or - 0.49 Ma for an andesite flow overlying marine strata at the latter site, indicate a middle Miocene age for the Unga Conglomerate Member of the Bear Lake Formation at Cape Aliaksin. The age inforerred from the mollusks at these three localities suggests assignment of these strata to the lower part of the Bear Lake Formation.

The Ukolnoi Island molluscan faunule of 18 species lived at depths of about 25 to 35 m in a cool-temperate to subtropical habitat. The presence of some warm-temperate to subtropical Asian taxa suggests that this faunule lived during the peak of the middle Miocene warm interval known throughout the North Pacific region.
Report by: Louie Marincovich , Jr.
Age: Middle Miocene
Formation: Bear Lake Formation
Occurrence(s)
No. Group Name Qty Notes
1 Bivalves Acila sp. indet. 1
2 Bivalves Yoldia sp. indet. 1
3 Bivalves Lucinoma acutilineata (Conrad, 1849) 9
4 Bivalves Macoma sp. indet. 8
5 Bivalves Clinocardium sp. 2
6 Bivalves Pitar? sp. 2
7 Bivalves Mya (Mya) truncata Linnaeus, 1758 4
8 Bivalves Mya sp. indet. 2
9 Snails Turritella (Hataiella) sagai Kotaka, 1951 12
10 Snails Colus? sp. 1
11 Snails Beringius crebicostatus (Dall, 1902) 1
12 Scaphopods Dentalium (Rhabdus) cf. D.(R.) schencki Moore, 1964 14