Sample Detail of
Sample: Sample No. 58AMER-F1
Locality: Field No. 58AMER-F1
Description: Collection was made from a graywacke unit which either lies upon or is interbedded with the surrounding volcanic rocks which have been assinged an Upper Cretaceous age on the basis of other fossils age determination. Location determined on Russian Mission Quadrangle, 1:250,000, 1950; 12.7 miles S 59 W from confluence of Buckstock and Aniak Rivers and 6.8 miles N 55 E of Mt. Hamilton. On crest of low ridge that lies approximately two miles east of and parallel to Discovery Creek. Fossils occur in fine-grained, platy graywacke which dips 30 degrees north. Graywacke with thin interbeds of dark-gray siltstone crops out for three miles to the north and one mile to the south. Collected August 27, 1958 by R.A. Jennings and L.H. Roth of Amerada Pet. Co. (description from transmittal sheet)
Location: Alaska Quadrangle: Russian Mission
Reference
Title: Report on Referred Fossils ,  1958 (12/19)
Report by: Ralph W. Imlay
Referred by: Joseph M. Hoare
Age: Bajocian-Callovian (middle Bajocian - Callovian)
Comment:The specimens of Inoceramus from locality F1 are Jurassic in age as suspected by David Jones and Arthur Grantz. They are identical specifically with the Inoceramus at Mesozoic localities 21481 and 21032 and 13430. They belong to a line of Inoceramus that in the Cook Inlet area first appeared in the Fitz Creek member (middle Bajocian) of the Tuxedni formation and ranged upward into the Chinitna formation (Callovian). They were described by Eichwald (1871) under the names I. eximius, I. porrectus, and I. ambiguus. these are probably all variants of a single species. I notice that I have used the name I. ambiguus Eichwald more commonly than the other names proposed by Eichwald. A detailed study will be necessary before this Inoceramus lineage will be of much stratigraphically. Eichwald's book is now with David Jones at Menlo Park if you are interested in looking at the original illustrations of the species mentioned.
Occurrence(s)
No. Group Name Qty Notes
1 Bivalves Inoceramus belongs to a lineage that ranges from the middle Bajocian to the Callovian in the Cook Inlet region