Reference Detail of

Report on Referred Fossils
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Stratigraphic range: Ordovician-Silurian
Kinds of fossils: Graptolites
Quadrangle or area: Eagle 1:250,000 quad.
Shipment No.: A-61-5D
Referred by: Brabb, Earl E.
Report prepared by: Ross, Reuben J., Jr
Date: 11/20/1961

These collections confirm that your Unit 5 is both Ordovician and Silurian. Furthermore they suggest the same question that we are so far unable to answer in Nevada; where is the Lower Silurian?


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Brief statement of problem and remarks (from collector):
Mertie (1930, USGS Bull 836, pl. 7) maps 2 units in the vicinity of Chief Mountain, an argillite and chert of Middle Devonian age and a shale and chert of Ordovician age. Rube Ross (P&S E&R 1960) has identified graptolites of Silurian and Ordovician age from similar rocks nearby, suggesting that Mertie's older unit is Silurian as well as Ordovician. I believe that Mertie's subdivision was based largely on paleontologic evidence and is not justified. Two units (4 and 5 on attached sheet) can be traced locally from a change in vegetation tone, but these do not correspond to Mertie's units and I doubt that the subdivision can be mapped outside of the Chief Mtn. area. Nevertheles, stratigraphic control in this important section is urgently needed for helicopter mapping next summer.
User Note module to be added
61ABa1311A (D181-SD) , Eagle , Shale approximately in the middle of Unit 4 of Brabb. 3.3 miles N 37 deg. W from International Boundary Commission Monument 105; Lat. 64 deg. 57.5' N; Long. 141 deg. 03.1' W; Coords. 21.8, 17.3). Eagle 1/250,000 quad., Alaska. (description from Ross E&R report dated 11/20/61)
Possibly eurypterid. Possibly the telson of an aglaspid or limulid.
61ABa1372 (D180-SD) , Eagle , About 600' [Note by R.B. Blodgett: in archival copy kept in Anchorage Technical Data office, the number 600 has been crossed out and replaced with 700']above base of unit 5 of Brabb. 2.7 miles N 27 deg. W from IBC Monument 105. Lat. 64 deg. 57.1 N; Long. 141 deg. 02.5' W; Coords. (21.8, 17.2). Eagle 1/250,000 quad., Alaska. (description from Ross E&R report dated 11/20/61)
Monograptus sp. (cf. M. flexilis Elles but not reflexed distally and not as wide)
Monograptus sp. (no sicular ends)
61ABa1381 (D182-SD) , Eagle , About 475 feet [Note by R.B. Blodgett: the number 475 has been crossed on the archival copy in the Anchorage Technical Data office and replaced by the number 565' written above it] above base of unit 5. 2.7 miles N 24 deg. W from IBC Monument 105. Lat. 64 deg. 57.1' N; Long. 141 deg. 02.5' W; coords. (21.8, 17.2) Eagle 1:250,000 quad., Alaska. (description from Ross E&R report dated 11/20/61)
Monograptus spp. Preservation hinders determination of species.
61ABa1382 (D925-CO) , Eagle , About 200 feet [Note by R.B. Blodgett: the archival copy of this report kept in the Technical Data office in Anchorage has the number 200 crossed out, and replaced by number 240' written above it] above the base of unit 5. 2.5 miles N 24 deg. W from IBC Monument 105. Lat. 64 deg. 57' N; Long. 141 deg. 02.2' W. coords. (21.8, 17.2) Eagle 1:250,000 quad., Alaska. (description from Ross E&R report dated 11/20/61)
Dicellograptus cf. D. elegans
Dicellograptus .....
....... or Dicranograptus fragments
Orthograptus truncatus cf. O. t. var. richmondensis (Ruedemann)
Orthograptus cf. O. calcaratus (Lapworth)
Orthograptus calcaratus cf. O. c. var. vulgatus (Lapworth)
Orthograptus quadrimucronatus , a wide variety, probably new
61ABa1312 (D926-CO) , Eagle , About 25 feet above the base of Unit 5. 3.7 miles N 22 deg. W from IBC Monument 105; Lat 64 deg. 57.9' N; Long 141 deg. 02.6' W; coords (21.9, 17.3) Eagle 1/250,000 quad., Alaska. (description from Ross E&R report dated 11/20/61)
Dicellograptus ......
.... or Dicranograptus fragments
Orthograptus calcaratus (Lapworth)
Orthograptus cf. O. quadrimucronatus var. whitfieldi (J. Hall)
Orthograptus quadrimucronatus J. Hall
Orthograptus sp. (very small, may be immature)
Climacograptus tubuliferus Lapworth
Climacograptus phyllophorus Gurley
60ABa121 (D167 SD) , Charley River , Approximately 425 feet above base of unnamed shale and chert sequence that overlies Cambrian ls. along Tatonduk River.
graptolites culled from two previously submitted collections that have been obviously now mixed, one collection Ordovician, the other Silurian.