Reference Detail of

Report on Referred Fossils
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Stratigraphic range: Jurassic
Kinds of fossils: mollusks
Quadrangle or area: , Cook Inlet, Alaska
Shipment No.: AF-51-42
Referred by: Hartsock, John K.
Report prepared by: Imlay, Ralph W.
Date: 12/20/1951

The only fossil of stratigraphic value in the three lots from the Difficult member of the Tuxedni formation is an ammonite mold in lot 51AHa6. A clay squeeze of this ammonite compares closely with the adult whorls of Erycites from the basal beds of the Kialagvik formation on Wide Bay. You may recall that Don Miller and I found Erycites associated with Tmetoceras and Pseudolioceras at localities 48 AI 77 and 78 at a spot about 2.6 miles N. 77 W. of Fossil Point. This occurrence is about 350 feet above the highest lava beds and slightly lower stratigraphically than your lot 51AHa6. In Europe Tmetoceras characterizes the basal part of the Bajocian stage. The other genera occur in both the lower part of the Bajocian and the upper part of the Toarcian. From these occurrences it is evident that the thick lava sequence on Tuxedni Bay occupies the stratigraphic position of the Lower Jurassic.

The Gaikema member is represented certainly by lots 51AHa11a, b, c as shown by the presence of the ammonities Emileia, Lissoceras, and Sonninia. The same species were obtained on the south shore of Tuxedni Bay in unit 33 of the section measured by Stanton and Martin (see U.S.G.S. Bull. 776, p. 142) as shown by specimens in lots 3009 and 21263.

The Fitz Creek member is represented by lots 51AHa9 and 10 as shown by the presence of species of Stemmatoceras and Oppelia identical with species obtained on the south shore of Tuxedni Bay in unit 19 of the section measured by Stanton and Martin. Grantz found the same species of Stemmatoceras in his lot 51AGz136, which is a short distance northeast of your localities.

The correlations of these members have been discussed in previous memoranda and are shown by charts in your possession.


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Brief statement of problem and remarks (from collector):
Transmitter: John K. Hartsock
State or region: West side Ccok Inlet Quadrangle: SW quarter of 603, NW quarter of 585
Collector(s) & years(s): Hartsock-1951, Grantz-1951
Brief state of problem, and remarks: Fossil determination necessary in order to ascertain formations for correlation purposes.
User Note module to be added
51AHa2 (Mesozoic loc. 22716) , Kenai , About 3/4 mile up Diable Creek above junction with Difficult Creek and about 5 miles west of Fossil Point on Tuxedni Bay. (description from E&R report of Imlay dated Dec. 20, 1951; Shipment AF-51-42)[Transmittal sheet of Hartsock, dated Nov. 30, 1951 provides further details: "Traverse point 8H, about 3/4 miles up Diablo Creek from mouth (Diablo Creek is a short, steep tributary to Difficult Creek on south side of Tuxedni Bay). Pelecypods found in float of lower Tuxedni sandstone, Mid. Jurassic age; origin in cliffs not far above."][Shown as locality 35 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 60 deg. 09'56" N., 152 deg. 47'36" W.]
Meleagrinella sp.
Tancredia sp.
Camptonectes sp.
51AHa3 (Mesozoic loc. 22717) , Kenai , Float near head of Diable Creek a little higher upstream than 51AHa2. (description from E&R report of Imlay dated Dec. 20, 1951; Shipment AF-51-42)[Transmittal sheet of Hartsock, dated Nov. 30, 1951 provides further details: "Traverse point 10H, near head of Diablo Creek. Pelecypods found in float of lower Tuxedni sandstone; origin of float very near."][Shown as locality 32 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 60 deg. 09'54" N., 152 deg. 47'34" W.]
Pleuromya sp.
51AHa6 (Mesozoic loc. 22718) , Kenai , About 1 1/4 miles upstream from mouth of first tributary to Difficult Creek about 4 3/4 miles west of Fossil Point. (description from E&R report of Imlay dated Dec. 20, 1951; Shipment AF-51-42)[Transmittal sheet of Hartsock, dated Nov. 30, 1951 provides further details: "Traverse point 24H, about 1 1/4 miles upstream from mouth of first tributary to Difficult Creek. Poorly preserved ammonite impression in lower Tuxedni sandstone."][Shown as locality 36 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 60 deg. 10'07" N., 152 deg. 47'30" W.]
Erycites? sp.
51AHa11a, b, c (Mesozoic loc. 22723) , Kenai , Cub Creek about one mile upstream from junction with Bear Creek at a point 2 1/4 miles from Tuxedni Bay. Lot 51AHa 11 bb, collected 50 yards downstream, and lot 51AHa11c, collected 200 yards downstream from lot 51AHa11a. (description from E&R report of Imlay dated Dec. 20, 1951; Shipment AF-51-42)[Transmittal sheet of Hartsock, dated Nov. 30, 1951 provides further details: "11a: Traverse point 69H on Cub Creek about one mile up stream from intersection with Bear Creek. Ammonite collected from very fine-grained sandstone, probably Fitz Creek formation of Mid Jurassic age."; 11b: "Ammonite from approximately same horizon as 51AHa11a. Locality 50 yards downstream from traverse point 69H on Cub Creek. Probably Fitz Creek formation."; 11c: "Two hundred yards downstream from 69H. Ammonite collected from siltstone, probably Fitz Creek formation."][Shown as locality 45 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 60 deg. 07'14" N., 152 deg. 45'13" W.][Imlay, 1964, p. B23 provides following description: "J.K. Hartsock, 1951. Tuxedni Bay area. Near Bear Creek about 3 miles S. 62 deg. W. of mouth of Bear Creek. Gaikema Sandstone. From gray sandy shale in lower 150 ft."]
Emileia sp.
Lissoceras sp.
Sonninia sp.
51AHa12 (Mesozoic loc. 22720) , Kenai , About one mile above mouth of Hungryman Creek and one mile southwest of Fossil Point on Tuxedni Bay. (description from E&R report of Imlay dated Dec. 20, 1951; Shipment AF-51-42)[Transmittal sheet of Hartsock, dated Nov. 30, 1951 provides further details: "Traverse point 72H, about one mile up Hungryman Creek from its mouth, on the south side of Tuxedni Bay. Pelecypods collected from siltstone with sandstone layers, probably Fitz Creek formation."]; [Shown as locality 7 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 60 deg. 09'25" N., 152 deg. 42'51" W.]]
Pleuromya dalli (White)
51AHa9 (Mesozoic loc. 22721) , Kenai , About half a mile below head of a tributary of Bear Creek which joins Bear Creek at a point 2.53 miles from Tuxedni Bay. (description from E&R report of Imlay dated Dec. 20, 1951; Shipment AF-51-42)[Transmittal sheet of Hartsock, dated Nov. 30, 1951 provides further details: "One hundred yards upstream from traverse point 64H on Bear Creek, south side of Tuxedni Bay, about 1/2 mile below head of stream. Ammonite collected in siltstone believed to belong to Bowser formation."][Shown as locality 66 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 60 deg. 05'57" N., 152 deg. 45'13" W.][Imlay, 1964, p. B23 provides following description: "J.K. Hartsock, 1951. Tuxedni Bay area. On tributary of Bear Creek, 3.56 miles S. 38 deg. W. of mouth of Bear Creek. Fitz Creek Siltstone, 150 ft above base."]
Oppelia cf. O. subradiata (Sowerby)
51AHa10 (Mesozoic loc. 22722) , Kenai , 200 yards below head of same tributary to Bear Creek as in lot 51AHa9 and about 100 feet below summit of divide between Bear Creek and Johnson River. (description from E&R report of Imlay dated Dec. 20, 1951; Shipment AF-51-42)[Transmittal sheet of Hartsock, dated Nov. 30, 1951 provides further details: "Two hundred yards downstream from head of Bear Creek. Ammonite collected in float about 100 feet topographically below traverse point 65H on summit of divide between Bear Creek and Johnson River. ----- (illegible) came from Bowser siltstone, as nothing else was observed between this locality and the divide."][Shown as locality 71 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 60 deg. 05'53" N., 152 deg. 45'06" W.]
Stemmatoceras sp.