M1178 - Chichagof Bay Section (Oligocene of the United States)

Also known as M1178

Where: Aleutians East County, Alaska (55.7° N, 160.2° W: paleocoordinates 58.8° N, 154.0° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Stepovak Formation, Oligocene (33.9 - 23.0 Ma)

• Also within the type area of the Stepovak Formation ("series"). The Stepovak Formation reaches around 6500 ft in thickness and comprises sandstones and siltstones. Collection probably middle or early Oligocene. Collection from near middle of formation at base of unit 3.

• bed-level stratigraphic resolution

Environment/lithology: marine; brown, gray sandstone and black siltstone

• No paleoenvironmental reported.
• Tan to brown sandstone, massive, with some gray sandstone and black siltstone.

Size class: macrofossils

Collection methods: 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 44106: authorized by Austin Hendy, entered by Austin Hendy on 01.09.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

• No other fossils mentioned.
Bivalvia
 Nuculida - Nuculidae
"Acila aff. shumardi" = Acila (Truncacila) shumardi
"Acila aff. shumardi" = Acila (Truncacila) shumardi Dall 1909 divaricate nutclam
Also A. aff. praedivaricata
 Nuculanida - Yoldiidae
Yoldia sp. Möller 1842 clam
 Pectinida - Pectinoidae
 Ostreida - Ostreidae
Ostrea sp. Linnaeus 1758 oyster
 Cardiida - Mactridae
Spisula sp. n. sp. Gray 1837 clam
Comments: A very trigonal form (?= Mesodesma alaskensis)
 Pholadida - Myidae
? Mya sp. Linnaeus 1758 softshell clam
 Lucinida - Thyasiridae
Thyasira sp. Lamarck 1818 clam
Scaphopoda
 Dentaliida - Dentaliidae
Dentalium sp. Linnaeus 1758 tusk shell
Gastropoda
 Sorbeoconcha - Naticidae
? Natica sp. Scopoli 1777 moon snail