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Reference
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| Title: |
Report on Referred Fossils
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1978
(12/05)
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| Report by: |
Warren O. Addicott
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| Referred by: |
George Plafker
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| | Age: | Late Eocene (Late Eocene ?) |
| Formation: | Yakataga Formation; Poul Creek Formation (Yakataga Formation or Poul Creek Formation) |
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| Comment: | The many specimens of what seems to be VERTIPECTEN have ribbing that rather closely resembles the latest Eocene species V. PORTERENSIS (Weaver) from southwestern Washington. That species occurs in strata referable to the “Lincoln” or Galvinian Stage and which also can be assigned to the Refugian Stage of the benthic foraminifer chronology. These units are nowadays though to be of late Eocene age; formerly they were treated, at least in part, as Oligocene. Preservation of these pectinid specimens is such that external surfaces are not preserved, nor are there any specimens that clearly show the configuration and size of the ears. Thus the identification is doubtful. The specimens do seem to be VERTIPECTEN owing to an intensification of the more inflated valve (these are fractures that are seen on the left valve). So far as is known VERTIPECTEN specimens with irregular ribbing such as these are known from post-Refugian (ACILA SHUMARDI zone) strata in Alaska. There is a pretty good suggestion, then, that this unit is latest Eocene in age. The rather smooth shelled specimens that seem to be closest to YABEPECTEN are an enigma. This smooth shelled, or relatively so, genus is a late Miocene indicator both in the eastern and western North Pacific (it ranges into the Pliocene in the latter area). The 2 or 3 fragments are so incomplete and the preservation is so poor, that these could well represent something else and might not even be pectinids. So, in conclusion a late Eocene age seem rather likely but the scrappy, smooth shelled pectinid-like fossil specimens that may represent YABEPECTEN indicate that an age as young as late Miocene is a possibility. |
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