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Reference
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| Title: |
Report on Referred Fossils
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1971
(10/29)
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This report covers a collection of Paleozoic corals from the north side of the Denali fault, Delta River--Mt. Hayes area. The single associated ammonite piece (float) has been transmitted to Ralph Imlay in Washington, D.C., after consultation with D.L. Jones of this Branch. |
| Report by: |
C. W. Merriam
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| Referred by: |
James H. Stout
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| | Age: | Silurian-Devonian |
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| Comment: | The corals with intermixed crinoidal material are of either Silurian or Devonian age as indicated by the unusually well-preserved Heliolites. In my experience in the Cordilleran belt of North America Heliolites is far more common in the Middle and Late Silurian. I have found this genus in only one part of the Devonian where the stratigraphy is well known and that is in the Great Basin upper Middle Devonian just below the Stringocephalus zone. Without other fossils the age of your fossils is uncertain but it may well be Silurian.
Coral specimens are returned to you. |
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| Title: |
Report on Referred Fossils
,
1971
(11/18)
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| Report by: |
Ralph W. Imlay
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| Referred by: |
James H. Stout
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| | Age: | Cretaceous (Cretaceous?) |
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| Comment: | The fragmentary ammonite found in float by James H. Stout north of the Denali fault zone in east-central Alaska is too poorly preserved for positive generic idenitifcation. Its rib pattern, however, does not remind me of any Jurassic genus but does remind me of the Upper Cretaceous genus Eupachydiscus (see p. L379 in the Treatise) as well as the outer whorls of some Lower Cretaceous ammonites described as Acanthoplites by Frank Anderson (1938, GSA Special Paper 16, p. 171-176). The Alaskan specimen, as on Eupachydiscus, bears strong ribs that alternate long and short, trend forward on the flanks, cross the venter transversely and are strongest on the venter. The long ribs curve backward sharply at the edge of the umbilicus and appear to be swollen at the points of greater curvature. The fact that the Alaskan specimen is only a fragment of a large septate whorl suggests that the species attained a size as large as that of Eupachydiscus.
[Transmittal sheet contains photocopy of field map showing location. - comment by R.B. Blodgett]
[Fossil material is the first collected from the north side of the Denali Fault in the Delta River-Mt Hayes area. The collected material is unmetamorphosed, but bears strong similarities to adjacent crystalline schists traditionally referred to as Birch Creek Schist - statement from transmittal sheet of J.H. Stout] |
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