M1168 - Tolstoi Peak section (Eocene of the United States)

Also known as M1168

Where: Aleutians East County, Alaska (55.4° N, 161.5° W)

• Paleocoordinates: 66.3° N, 151.4° W (Wright 2013)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Tolstoi Formation, Middle Eocene (47.8 - 37.7 Ma)

• The formation contains the oldest Tertiary rocks on the Alaska Peninsula; marine mollusks were determined as middle Eocene; and plants were dated as probably Paleocene. Neither base or top of sequence is represented in the section, but both are apparent locally. The basal contact shows no sharp angular discordance with the Hoodoo Formation, but black shales and siltstones of both are very difficult to distinguish. The top of the Tolstoi Formation appears to be conformable with Oligocene Stepobak Formation, but the contact is complicated by faulting.

• bed-level stratigraphic resolution

Environment/lithology: marine; brown, gray, green, carbonaceous sandstone and volcaniclastic conglomerate

• No paleoenvironmental data reported. Marine, probably shallow water as overlies brackish water assemblages.
• Greenish-gray to brown poorly sorted sandstones, massive to well-bedded, with few conglomerates of much volcanic material, and some gray to dark gray well-bedded shale, claystone and siltstone.

Size class: macrofossils

Collection methods: quarrying,

• Collections examined by F.S. MacNeil and D. Taylor (USGS), 1962. Collections are reposited at USGS Menlo Park, or presumably USNM (not reported)

Primary reference: C.A. Burk. 1965. Geology of the Alaska Peninsula-island arc and continental margin (Part 1). Geological Society of America Memoir 99(1) [A. Miller/A. Hendy/A. Hendy]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 44070: authorized by Austin Hendy, entered by Austin Hendy on 31.08.2004

Creative Commons license: CC0 (CC0)

Taxonomic list

• Some other fossils mentioned, but not named.
Gastropoda
 Opisthobranchiata - Cylichnidae
Cylichna sp. Lovén 1846 snail
 Sorbeoconcha - Naticidae
Natica sp. Scopoli 1777 moon snail
 Neogastropoda - Fasciolariidae
Perse sp. Clark 1918 snail
 Cerithioidea - Turritellidae
Turritella uvasana Conrad 1855 turret shell
Bivalvia
 Cardiida - Veneridae
Costacallista conradiana Gabb 1864 venus clam
 Cardiida - Cardiidae
"Plagiocardium (Schedocardia) breweri" = Schedocardia brewerii
"Plagiocardium (Schedocardia) breweri" = Schedocardia brewerii Gabb 1864 cockle
 Carditida - Carditidae
"Venericardia aff. clarki" = Venericardia (Pacificor) clarki
"Venericardia aff. clarki" = Venericardia (Pacificor) clarki Weaver and Van Winkle Palmer 1922 clam
 Arcida - Glycymerididae