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Reference
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| Title: |
Report on Referred Fossils
,
1955
(12/20)
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| Report by: |
R. A. Scott
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| Referred by: |
Charles E. Kirschner
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| | Age: | No Data |
| Formation: | Kaguyak Formation (Revised; Robert B. Blodgett, 02/09/2008 ) |
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| Comment: | Material: One (1) specimen from locality CEK 744 consisting of a 5" segment of a silicified log 12" in diameter." Identification: Generic identification of this coniferous wood is not possible due to the poor quality of the preservation. The poor preservation is surprising, for the gross appearance of the specimen indicates that it would be ideal for study. It is uncompressed and black in color, indicating the presence of much of the original organic material. However, thin sections show that the cell walls were subjected to extensive degradation and cracking prior to silicification. Most of the diagnostic features have been obliterated. |
| Occurrence(s) |
| No. |
Group |
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Name |
Qty |
Notes |
| 1 |
Plants |
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silicified log |
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| Title: |
Report on Referred Fossils
,
1955
(11/04)
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These collections that have been submitted have furnished information that should be of interest to many geologists and are well worth keeping in the Survey Collections. Their value would be greater if the locations of the various collections were shown on index maps. These would be filed with the reports and be available for future use by anyone. Such maps would be appreciated, especially for areas in which localities are difficult to describe. [Note: these collections were referred by C.E. Kirschner through George Gates] |
| Report by: |
Ralph W. Imlay
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| Referred by: |
Charles E. Kirschner
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| | Age: | Late Cretaceous |
| Formation: | Kaguyak Formation (Revised; Robert B. Blodgett, 02/09/2008 ) |
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| Comment: | The collection of Cretaceous fossils from the head of the Alaskan Peninsula are of very late Late Cretaceous age. The collection containing Pachydiscus subcompressus Matsumoto and P. suciaensis (Meek) are probably as late as early Maestrichtian. The same species occurs elsewhere in Alaska in the Matanuska Valley near the top of the shale and siltstone member of the Matanuska formation. They occur on Vancouver Island in the Lambert formation (see Ushur, Canada Geol. Survey Bull. 21, p. 34). Some of the species occur in California near the top of the Panoche formation. In Japan they, or very similar species, occur at the very top of the Cretaceous sequence. The presence of very smooth, compressed pachydiscid ammonites, such as in the collections submitted, are evidence of a position near the top of the Cretaceous. It is interesting, therefore, that collections CEK-742 contains the belemnite Acroteuthis of Valanginian to Barremian age and collection CEK-744 contains both Acroteuthis and Cylindoteuthis. The latter could be of Neocomian age but is more apt to be of Late Jurassic age. It is locally common in the Naknek formation. The belemnites appear to be worn and somewhat rounded. Their presence is good evidence that the beds of Late Jurassic age (Naknek or younger) and Neocomian age were being eroded during latest Cretaceous time in areas on or near the Alaskan Peninsula. Beds of Neocomian age may be expected to be found in both surface and subsurface during future exploration. This is not the first instance of reworked belemnites occurring in Upper Cretaceous beds in Alaska> Some specimens of Cylindoteuthis were found with Late Cretaceous (Santonian to Campanian) ammonites and Inocerami at Mes. loc. 5587 near Hot Springs, Port Moller, Alaska. Acroteuthis occurs in the Kotsina-Kuskulana district (See U.S.G.S. Bull. 776, pp. 352-354) in association with Inocerami (Mes. locs. 8936, 8940, 8155) that are identical with species at the basal part of the Matanuska formation in the Talkeetna Mountains. The basal part of the Matanuska formation is considered to be Conician age. Acroteuthis, also, occurs in the Kuskulana district in collections 9949, 9954, and 9955 associated with ammonites of Albian age. Some of the belemnites are much worn and rounded and are associated with pebbles. Elsewhere Acroteuthis occurs in enormous numbers in the Talkeetna Mountains on the surface of the Nelchina limestone at the base of a sequence of Albian age. These belemnites appear to be residual. They indicate that Neocomian formerly included more than the Nelchina limestone and the underlying arkosic sandstones. |
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