Reference Detail of

Report on Referred Fossils
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Stratigraphic range: Jurassic
Kinds of fossils: Marine invertebrates
Quadrangle or area: , west side Cook Inlet
Shipment No.: AF-49-10
Referred by: Hartsock, John K. , Miller, Don J. , Grantz, Arthur
Report prepared by: Imlay, Ralph W.
Date: 01/16/1950

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.

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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.


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Brief statement of problem and remarks (from collector):
Transmittal sheet signed by Arthur Grantz (for J.K. Hartsock)
User Note module to be added
48AMr146 (Mesozoic loc. 21303) , Iliamna , Tuxedni formation. middle siltstone member. Gray sandy siltstone about 800 feet below Cynthia Falls sandstone member on Fitz Creek near head, 2.51 miles S. 11 deg. E. of Tonnie Peak, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Detterman and Hartsock, 1966, p. 32 (faunal list), loc. 86 on Pl. 3][Shown as locality 86 on Pl. 3 of Detterman and Hartsock, 1966]
Chondroceras (Defonticeras) sp.
49AMr37 (Mesozoic loc. 21767) , Iliamna , Tuxedni formation, middle siltstone member. Probably same stratigraphic position as 48AMr147 (Mes. loc. 21304) but on opposite flank of anticline. On south bank of Fitz Creek, 2.45 miles S. 10 deg. 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: "Outcrop of middle siltstone member of Tuxedni formation near axis of anticline, south bank of Fitz Creek, 2.46 miles S. 10 deg. E. of Tonnie Peak. Should be same stratigraphic horizon as lot 21304 (48AMr147) but on opposite flank of anticline."][Detterman and Hartsock, 1966, p. 32 (faunal list), loc. 78 on Pl. 3][Shown as locality 78 on Pl. 3 of Detterman and Hartsock, 1966]
Chondroceras (Defonticeras) sp.
Normannites sp.
Teloceras sp.
Oxytoma sp.
Gastropods undetermined
49AMr38 (Mesozoic loc. 21768) , Iliamna , Tuxedni formation, middle siltstone member. 50 to 150 feet below top of member on south bank of Fitz Creek, 2.35 miles S. 2 deg. E. of Tonnie Peak, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "100 foot interval of middle siltstone member of the Tuxedni formation, 50-150 feet below the top of the member; outcrop on south bank of Fitz Creek, 2.35 miles S. 2 deg. E. of Tonnie Peak."][Shown as locality 106 on Pl. 3 of Detterman and Hartsock, 1966]
Chondroceras (Defonticeras) sp.
Stephanoceras spp.
48AMr144 (Mesozoic loc. 21306) , Iliamna , 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. 55 deg. 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]
Chondroceras (Defonticeras) sp.
49AMr39 (Mesozoic loc. 21769) , Iliamna , Tuxedni formation, Cynthia Falls member. Basal part of top of middle siltstone member, on southwest bank of Fitz Creek, 0.2 miles below the I.B.A. well; 1.94 miles S. 64 deg. E. of Tonnie Peak, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Siltstone outcrop on SW bank of Fitz Creek 0.2 mile below I.B.A. well; 1.94 miles S. 64 deg. E. of Tonnie Peak. Field relations indicate basal Cynthia Falls or top of middle siltstone member of the Tuxedni formation."][Detterman and Hartsock, 1966, p. 32 (faunal list), loc. 89 on Pl. 3][Shown as locality 89 on Pl. 3 of Detterman and Hartsock, 1966]
Chondroceras (Defonticeras) sp.
Phylloceras sp.
49AMr40 (Mesozoic loc. 21770) , Iliamna , Tuxedni formation, probably middle siltstone member. Isolated outcrop of siltstone on northwest bank of Fitz Creek, 1.75 miles S. 83 deg. E. of Tonnie Peak, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Microfossils from isolated outcrop of siltstone on NW bank of Fitz Creek, 1.75 miles S 83 E of Tonnie Peak. This outcrop is either lower or middle siltstone member of the Tuxedni--identification is critical to the interpretation of the structure. Unfortunately, only pelecypods could be found; can anything be determined from them?"]; [Shown as locality 1 on Pl. 3 of Detterman and Hartsock, 1966]
Inoceramus sp.
Pleuromya sp.
Grammatodon sp.
49AMr42 (Mesozoic loc. 21771) , Iliamna , Tuxedni formation, middle siltstone member. Upper part, from southeast side of Fitz Creek, 2.8 miles N. 71 deg. E. of Tonnie Peak, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Microfossils from siltstone outcrop on SE of Fitz Creek, 2.8 miles N 71 E of Tonnie Peak. Field relations indicate upper part of middle siltstone member of the Tuxedni formation."][Shown as locality 117 on Pl. 3 of Detterman and Hartsock, 1966]
Chondroceras (Defonticeras) sp.
Grammatodon sp.
Rhynchonellid brachiopod undetermined
49AHa65 (Mesozoic loc. 21779) , Iliamna , Tuxedni formation?, Bowser member?. From Don Miller's point B 79 coll. 48AMr140 (Mes. loc. 21336), at point 1.23 miles S. 67 deg. E. of Horn Mountain on north side of Chinitna Bay. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Pelecypods and belemnites from Miller's point B 79, collection 48AMr140, in canyon east of Horn Mtn. Page 66, 1949. September 12, 1949."][Detterman and Hartsock, 1966, p. 39 (faunal list), loc. 173 on Pl. 3][Shown as locality 173 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 53'09" N., 153 deg. 04'21" W.]
Belemnite ......
...... and ammonite fragments
Pholadomya sp.
Pleuromya sp.
Quenstedtia sp.
Astarte sp.
Protocardia sp.
Pteroperna? sp.
Gastropod undetermined
49AHa69 (Mesozoic loc. 21773) , Iliamna , Tuxedni formation, Bowser member. From boulder on tidal meadow at base of Cynthia Falls sandstone, 1 1/2 miles northeast of mouth of Fitz Creek, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Ammonites from boulder on tidal meadow at base of Cynthia Falls sandstone 1 1/2 miles northeast of mouth of Fitz Creek. Collected by Don J. Miller. Cranocephalites or Defonticeras? Page 67, September 13, 1949][Shown as locality 191 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 48'58" N., 153 deg. 06'34" W.]
Cranocephalites spp.
49AGz1 (Mesozoic loc. 21772) , Iliamna , Tuxedni formation, middle siltstone member or Cynthia Falls member. Concretion from drift in gully 0.5 miles east of Fitz Creek on south shore of Chinitna Bay, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Ammonite in concretion from drift in gully 0.5 miles east of Fitz Creek, at shore of Chinitna Bay. Middle siltstone or Cynthia Falls member of Tuxedni."][Shown as locality 116 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 48'37" N., 153 deg. 07'20" W.]
Teloceras sp.
49AGz2 (Mesozoic loc. 21766) , Iliamna , Tuxedni formation, lower siltstone member. 100 to 150 feet below the Gaikema member, from gully 1.6 miles west of Fitz Creek between points 48 AI 17 and 48 AI 18, on south south side of Chinita Bay, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Macrofossils from gully 1.6 miles west of Fitz Creek between points 48 AI 17 and 48 AI 18 and also Millers points 15 and 16. Massive green siltstone of the upper part part of the lower siltstone of the Tuxedni, 100-150 feet below the Gaikema, (or break in slope.)"][Detterman and Hartsock, 1966, p. 24 (faunal list), loc. 6 on Pl. 3]
Stephanoceras sp.
Pleuromya sp.
Trigonia sp.
49AHa62 (Mesozoic loc. 21774) , Iliamna , Chinitna formation, lower member from gully trending south at point 6D on beach on south side of Chinitna Bay opposite Gull Island, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Ammonite and pelecypod from gully running south from point 6D on beach, south side of Chinitna Bay, Stratigraphic position, Lower member of Chinitna formation. Collected by Don J. Miller, Page 56, September 2, 1949."][Shown as locality 251 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 49'59" N., 153 deg. 01'48" W.]; [J. K. Hartsock, 1949. Iniskin Peninsula, south side of Chinitna Bay opposite Gull Island in south trending gully, Chinitna formation, near top of middle third. (description from Imlay, 1953, p. 66)]
Caloceras sp.
Astarte sp.
49AHa63 (Mesozoic loc. 21775) , Iliamna , Chinitna formation, upper member, from gully in ridge on north side of Chinitna Bay NNW of Gull Island. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Pelecypods from gully in ridge on north side of Chinitna Bay, north-northwest from Gull Island. From dark siltstone of Upper member of the Chinita formation. Page 62, September 10, 1949."][Detterman and Hartsock, 1966, p. 48 (faunal list), loc. 295 on Pl. 3][Shown as locality 295 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 53'23" N., 153 deg. 01'47" W.]
Belemnite fragments
Grammatodon sp.
Tancredia sp.
49AHa66 (Mesozoic loc. 21780) , Iliamna , Chinitna formation?, from Miller's point B 80 in canyon east of Horn Mountain, north of Chinitna Bay. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Exceptionally coarse-ribbed Inoceramus from Miller's point B 80, in canyon east of Horn Mtn. Any age significance to the coarse ribbing? Page 66, September 12, 1949."][locality not listed in text or shown on Pl. 3 of Detterman and Hartsock, 1966]
Inoceramus sp.
49AHa67 (Mesozoic loc. 21781) , Iliamna , Chinitna formation, lower member, from fore of cascade about 50 yards east of Miller's point B 83, in tributary to canyon east of Horn Mountain. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Ammonites, pelecypods and belemnites from fore of cascade about 50 yards east of Miller's point B 83, in tributary to canyon east of Horn Mtn. From dark siltstone, probably Chinitna. Page 66, September 12, 1949."][Shown as locality 248 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 53'31" N., 153 deg. 04'04" W.]; [J.K. Hartsock, 1949. North side of Chinitna Bay, tributary to large canyon east of Horn Mountain, from face of Cascade about 50 yd east of loc. 21338, Chinitna formation, near middle of middle third. (description from Imlay, 1953, p. 66)]
Cadoceras sp.
Pseudocadoceras grewingki (Pompeckj)
Belemnite fragments
Oxytoma sp.
Echinotis sp.
Grammatodon sp.
Pinna sp.
49AGz19 (Mesozoic loc. 21776) , Iliamna , Chinitna formation, upper member, 1.1 miles west of Gull Island, south shore of Chinitna Bay, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Cadoceras, from float below undifferentiated thick siltstone of the upper member of the Chinitna Formation, 1.1 miles west of Gull Island, south shore of Chinitna Bay."][Detterman and Hartsock, 1966, p. 48 (faunal list), loc. 288 on Pl. 3][Shown as locality 288 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 50'54" N., 153 deg. 01'12" W.]; [A. Grantz, 1949. Iniskin Peninsula, south shore of Chinitna Bay 1.1 miles west of Gull Island. Float from thick siltstone of the upper third of the Chinitna formation. (description from Imlay, 1953, p. 66)]
Cadoceras sp.
49AGz33 (Mesozoic loc. 21777) , Iliamna , Chinitna formation, lower part of upper member, 1.2 to 1.3 miles west of Gull Island on south shore of Chinitna Bay, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Macrofossils from the siltstone with thin lime and lime concretion beds of the lower part of the upper Chinitna 1.2 to 1.3 miles west of Gull Island, south shore of Chinitna Bay."][Detterman and Hartsock, 1966, p. 48 (faunal list), loc. 297 on Pl. 3][Shown as locality 297 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 50'01" N., 153 deg. 01'20" W.]; [A. Grantz, 1949. Iniskin Peninsula, south shore of Chinitna Bay from 1.2 to 1.3 miles west of Gull Island from siltstone and thin limestones in the lower part of the upper third of the Chinitna formation. (description from Imlay, 1953, p. 66)]
Cosmoceras? sp.
Pseudocadoceras spp.
Phylloceras spp.
Belemnite fragments
Gastropods indetermined
Grammatodon sp.
Camptonectes sp.
49AGz34 (Mesozoic loc. 21778) , Iliamna , Chinitna formation, upper member, from lower half of the upper half of upper member, 1.0 to 1.1 miles west of Gull Island on south shore of Chinitna Bay, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Macrofossils from the lower half of the massive siltstone of the upper half of the upper Chinitna, 1.0 to 1.1 miles west of Gull Island, south shore."][Detterman and Hartsock, 1966, p. 48 (faunal list), loc. 293 on Pl. 3] [Note by R.B. Blodgett: locality number mistakenly entered as 48AGz34 in text of E&R report, but correctly listed as 49AGz34 in transmittal sheet of Grantz][Shown as locality 293 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 50'03" N., 153 deg. 01'20" W.]; [A. Grantz, 1949. Iniskin Peninsula, south shore of Chinitna Bay from 1.0 to 1.1 miles west of Gull Island, lower half of the massive siltstone forming the upper half of the upper third of the Chinitna formation. (description from Imlay, 1953, p. 66)]
Pseudocadoceras spp.
Phylloceras sp.
Belemnite undetermined
Grammatodon sp.
49AGz15 (Mesozoic loc. 21782) , Iliamna , Naknek formation, from large blocks below basal Naknek, 0.8 to 0.9 miles west of Gull Island along south shore of Chinitna Bay, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Cardioceras, from float below basal Naknek, (from large talus blocks) 0.8 to 0.9 miles west of Gull I. along south shore of Chinitna Bay."][Shown as locality 308 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 50'00" N., 153 deg. 00'50" W.]; Arthur Grantz, 1949. South shore of Chinitna Bay. 1.3-1.4 km west of Gull Island at same place as Mesozoic loc. 11002. Naknek Formation, unnamed lower sandstone member, 61-76 m above base. Early Oxfordian. (description from Imlay, 1981, USGS PP 1190, p. 25); [USGS Mesozoic Catalogue: Orig. no. 49AGz15. Jurassic - Naknek. Same geographic location as (for?) 21775. Cardioceras, from float below basal Naknek (from large talus block) 0.8 to 0.9 miles west of Gull Island along south shore of Chinitna Bay. Coll. Grantz. 1949.]
Cardioceras martini Reeside
49AGz35 (Mesozoic loc. 21783) , Iliamna , Naknek formation, from upper half of the massive sandstone beds of the lower Naknek just below the black, limy siltstone of the middle Naknek, 0.7 miles west of Gull Island on south shore of Chinitna Bay. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Ammonite (Phylloceras?) from the upper half of the massive sandstone beds of the lower Naknek, immediately below the black limey siltstone of the middle Naknek, 0.7 miles of west of Gull Island, south shore."][Shown as locality 310 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 49'51" N., 153 deg. 00'28" W.];Arthur Grantz, 1949. South shore of Chinitna Bay, 1 km west of Gull Island and 0.3 km southwest of Mesozoic 1oc.-21351. Naknek Formation, unnamed lower sandstone member, 244 m above base. Early Oxfordian. (description from Imlay, 1981, USGS PP 1190, p. 25); [USGS Mes. Cat.: Orig. no. 49AGz35. Jurassic-Naknek Fm. Cook Inlet Region, west side of Cook Inlet & Chinitna Bay district, NE1/4, NW1/4, NW1/4 Quadrangle 585, Alaska. Ammonite (Phylloceras) from the upper half of the massive sandstone beds of the lower Naknek, immediately below the ??? limey siltstone of the Middle Naknek, 0.7 miles west of Gull Island, south shore. Coll. Grantz, 1949.]
Phylloceras sp.
49AGz36 (Mesozoic loc. 21784) , Iliamna , Naknek formation, lower part, about 0.8 mile west of Gull Island on south shore of Chinita Bay, Iniskin Peninsula. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Macrofossils from the massive sandstone beds of the lower Naknek about 0.8 miles west of Gull Island, south shore."][Shown as locality 209 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. 38'05" W.]; [USGS Mes. Cat.: Orig. no. 49AGz36. Jurassic-Naknek Fm. Same geographic location as No. 21783, Macrofossils from the massive sandstone beds of the lower Naknek about 0.6 miles west of Gull Island, south shore. Coll. Grantz, 1949.]
Cardioceras martini Reeside
Oxytoma sp.
Pholadomya sp.
Thracia? sp.
Quenstedtia sp.
Astarte? sp.
49AGz37 (Mesozoic loc. 21785) , Iliamna , Naknek formation, from limy siltstone of middle part, 0.6 miles west of Gull Island on south shore of Chinitna Bay. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Ammonite (Phylloceras?) from the limey siltstone of middle Naknek 0.6 miles west of Gull Island, south shore."][Shown as locality 313 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 49'47" N., 153 deg. 00'07" W.]; Arthur Grantz, 1949. South shore of Chinitna Bav at same place as Mesozoic loc. 21352. Naknek Formation, Snug Harbor Siltstone Member, 183 m above base. Late middle to late Oxfordian. (description from Imlay, 1981, USGS PP 1190, p. 25); [USGS Mes. Cat.: Orig. no. 49AGz37. Jurassic-Naknek Fm. Same geographical locality as No. 21783. Ammonite Phylloceras from the limey siltstone of the Middle Naknek 0.6 miles west of Gull Island, South shore. Coll. Grantz, 1949.]
Phylloceras sp.
49AGz45 (Mesozoic loc. 21786) , Iliamna , Naknek formation, probably same locality as preceding 49AGz37, but label was separated in transit. (description from Imlay E&R report of 1/16/50)[Grantz transmittal sheet of Nov. 23, 1949 provides following description: "Ammonite probably from the limey siltstone of the middle Naknek 0.6 miles west of Gull Island, south shore of Chinitna Bay. (Separated from label in transit)."][Shown as locality 313 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59 deg. 49'47" N., 153 deg. 00'07" W.]; Arthur Grantz, 1949. South shore of Chinitna Bay, 1 km west of Gull Island, a little southeast of Mesozoic loc. 21783 in the same section, Iliamna (D-1) Quadrangle. Naknek Formation. Snug Harbor Siltstone Member. 183 m above base, Oxfordian. (description from Imlay, 1981, USGS PP 1190, p. 25); [USGS Mes. Cat.: Orig. no. 49AGz45. Jurassic-Naknek. Same geographical locality as No. 21783. Ammonite probably from the limey siltstone of the Middle Naknek. 0.6 miles west of Gull Island, South shore - Chinitna. Coll. Grantz, 1949.]
Phylloceras sp.