Sample Detail of
Sample: Sample No. 48AMr144 -- USGS No. Mesozoic loc. 21306
Locality: Field No. 48AMr144
Description: Tuxedni formation, Cynthia Falls member. Basal part, or top of middle siltstone member, on stream entering Fitz Creek from southeast near I.B.A. well, 2.17 miles S. 55o E. of Tonnie Peak, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Transmittal sheet of Grantz dated Nov. 23, 1949 provides following description: "Additional microfossil collection from the 1948 locality (lot 21306). Field relations indicate either basal Cynthia Falls or top of Middle siltstone member of the Tuxedni formation."][Detterman and Hartsock, 1966, p. 32 (faunal list), loc. 84 on Pl. 3][Shown as locality 84 on Pl. 3 of Detterman and Hartsock, 1966]
Location: Alaska Quadrangle: Iliamna C-1
Reference
Title: Report on Referred Fossils ,  1950 (01/16)
Title: Report on Jurassic fossils from west side of Cook Inlet, southwestern Alaska, submitted by John A. Hartsock and Don Miller, December 15, 1949 (AF-49-10) Examination has been made of the collections of Jurassic fossils made in 1949 along the west side of Cook Inlet by Miller, Hartsock, and Grantz. There is no question concerning the age or stratigraphic position of most of the collections but a few require comment.

........

None of the other lots present any age problems. I hope to complete describing the Callovian ammonites early this spring and at that time will sent you a summary of conclusions.
Report by: Ralph W. Imlay
Referred by: John K. Hartsock , Don J. Miller , Arthur Grantz
Age: Jurassic (Jurassic, no further definitive age is given in E&R report)
Formation: Cynthia Falls Sandstone (Cynthia Falls member of the Tuxedni formation)
Comment:Tuxedni formation

Lot 48AMr144 (Mes. loc. 21306) likewise contains Chondroceras (Defonticeras) which shows that it comes from the middle siltstone member or the Cynthia Falls member and is older than the Bowser member.

Occurrence(s)
No. Group Name Qty Notes
1 Ammonoids Chondroceras (Defonticeras) sp.

Title: Geology of the Iniskin-Tuxedni Region, Alaska ,  1966
Report by: Robert L. Detterman , John K. Hartsock
Age: Bajocian (middle Bajocian)
Formation: Fitz Creek Siltstone
Comment:Geographic location: Fitz Creek area
Map reference (pl. 3): 84
Stratigraphic position below top of formation (ft): 450-500
all above data from Table 6, p. 32
Occurrence(s)
No. Group Name Qty Notes
1 Ammonoids Chondroceras cf. C. allani (McLearn)
2 Ammonoids Chondroceras sp.
3 Ammonoids Normannites (Itinsaites) cf. (I.) variabilis Imlay