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Reference
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| Title: |
Report on Referred Fossils
,
1955
(09/30)
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| Report by: |
Ralph W. Imlay
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| Referred by: |
A. S. Keller
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| | Age: | Late Cretaceous (late Late Cretaceous) |
| Formation: | Chignik Formation |
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| Comment: | The Inocerami from the Chignik formation show that its age is late Late Cretaceous. The species Inoceramus schmidti Michael, I. balticus Boehm of Nagao and Matumoto occur in the Matanuska formation directly above beds containing I. undulatoplicatus Roemer, which is a world-wide Santonian marker. In Japan I. schmidti and I. balticus occur in the same relative stratigraphic positions and Japanese paleontologists assign them to the Campanian and early Maestrichtian. I doubt whether these species are as late as Maestrichtian, but a Campanian age seems reasonable. The ammonite Canadoceras is a common associate of these Inocerami in Japan, in the Matanuska formation, and in the Chignik formation. The Japanese consider Canadoceras to be of late Campanian to early Maestricthtian age in Japan. However in Vancouver Island it occurs in beds of Santonian to Campanian age and does not occur in the highest fauna which is possibly of early Maestrichtian age. In the Redding area of California, Canadoceras has been found in beds that are identified confidently as Coniacian on the basis of the presence of the ammonite Peroniceras. It appears, therefore, that the presence of the genus Canadoceras does not permit as close an age determination as the Inocerami. |
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