Stratigraphy and Paleontology of 

the Revised Type Section for the 

Tahkandit Limestone (Permian) in 

East-Central Alaska 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 703 

Stratigraphy and Paleontology of 

the Revised Type Section for the 

Tahkandit Limestone (Permian) in 

East-Central Alaska 

By EARL E. BRABB and RICHARD E. GRANT 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 703 

Revisions in the definition, description, and 

paleontology of an Arctic Permian formation 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1971 
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary 

GEOLOGICAL SURVEY 

W. A. Radlinski, Acting Director 

Library of Congress catalog-card No. 70-611771 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 50 cents (paper cover) 

Stock Number 2401-1134 
CONTENTS 

Page Page 

Abstract Type section of the Tahkandit Limestone-Continued 

Introduction ----------------------------------------

Acknowledgments -------------------------------

Previous work ----------------------------------

1 

1 

1 

2 

2 

2 

4 

6 

6 

7 

7 

9 

Correlation of cliff section and slough section _____ 10 

Relation to overlying Glenn Shale ---------------- 11 

Thickness -------------------------------------- 11 

Type section of the Tahkandit Limestone -------------- Summary -------------------------------------- 11 

Location ---------------------------------------

Structural setting -------------------------------

Sandstone unit ----------------------------------

Definition and extent ------------------------

Lithology ----------------------------------

Fossils ------------------------------------- Relation to underlying Nation River Formation __ 

Limestone unit ---------------------------------

Lithology ----------------------------------

Fossils -------------------------------------

Repeated section ----------------------------

10 

10 

10 

10 

Tahkandit Limestone at other localities --------------- 11 

Brachiopods from the Tahkandit Limestone ___________ 11 

Age ------------------------------------------- 11 

Brachiopods from the sandstone unit ______________ 13 

Brachiopods from the limestone unit ------------- 13 

Systematic paleontology ----------------------------- 14 

Locality descriptions for Permian fossil collections from 

east-central Alaska ------------------------------- 17 

References cited ------------------------------------ 22 

Index ----~----------------------------------------- 25 

ILLUSTRATIONS 

[Plates follow index] 

PLATE 1. Fossils from the Tahkandit Limestone. 

2. Fossils from the Tahkandit Limestone. Page 

FIGURE 1. Map showing location of type section of Tahkandit Limestone --------------------------------------------- 2 

2-4. Photographs showing2. Location of original and revised type section----------------------------------------------------.,.- 8 

3. Section along Yukon River slough________________________________________________________________ 3 

4. Enlarged view of cliff section____________________________________________________________________ 4 

5. Stratigraphic sections of the Tahkandit Limestone in its type section_______________________________________ 5 

6. Sketch of geology at type section ---------------------------------------------------------------------- 6 

7. Photomicrograph showing sandstone texture____________________________________________________________ 7 

8. Photomicrograph showing prismatic pelecypod fragments_________________________________________________ 9 

9. Photograph showing contact between the Tahkandit Limestone and the Nation River Formation ------------ 9 

10. Photomicrograph showing fossil fragments cemented by calcite ------------------------------------------- 10 

11. Photomicrograph showing bioclastic limestone characteristic of the limestone unit of the Tahkandit Limestone _ 10 

TABLES 

Page 

TABLE 1. Brachiopods from the type section of the Tahkandit Limestone_____________________________________________ 8 

2. Brachiopods from the Tahkandit Limestone outside the type section________________________________________ 12 

3. Locality descriptions for Permian fossil collections from east-central Alaska_________________________________ 18 

m 

STRATIGRAPHY AND PALEONTOLOGY OF THE REVISED TYPE SECTION FOR THE 

TAHKANDIT LIMESTONE (PERMIAN) IN EAST-CENTRAL ALASKA 

By EARL E. BRABB and RICHARD E. GRANT 

ABSTRACT 

The type section for the Tahkandit Limestone is revised 

to include a massive cliff-forming limestone that apparently 

is displaced by a fault from the type section specified by 

Mertie (1930) as being along a slough of the Yukon River. 

Some of the limestone and sandstone in the slough section, on 

the other hand, seems to be repeated by faulting and is herein 

excluded from the type section. Also excluded are rocks that 

are more properly assigned to the underlying Nation River 

Formation of Late Devonian age. The Tahkandit type section 

is redefined to include a lower sandstone unit about 75 feet 

thick and an upper limestone unit about 270 feet thick. The 

combined thickness of about 345 feet is considerably less than 

the 527 or 2,065 feet reported previously. 

Abundant brachiopods from known stratigraphic positions 

within the Tahkandit are illustrated and discussed systematically for the first time. The faunas show affinities to Permian 

faunas in the Canadian Arctic Archipelago and central east 

Greenland and are probably correlative with the upper Leonard and lower Guadalupe Provincial Series of the Southwestern United States. 

INTRODUCTION 

Alaskan fossils of Permian age have been mentioned in many geologic reports since the late 1800's, 

but hardly any have been described or illustrated. 

The general character of one of these faunas, from 

the Tahkandit Limestone near the mouth of the Nation River in east-central Alaska (fig. 1), was described in a report by Mertie (1930, p. 125-126), but 

many of the fossil names that he listed are obsolete, 

and the stratigraphic position and evolutionary sequence of the fossils are unknown. Our report is, 

therefore, the first to describe and illustrate Tahkandit brachiopods from known positions within the 

type section, and it is the first illustrated report of 

Permian brachiopods from Alaska. 

Investigation of the Tahkandit Limestone is part 

of a project begun in 1960 to map the geology of 

eastern Alaska at a scale of 1:250,000. Preliminary 

geologic maps showing the type area of the Tahkandit Limestone and surrounding region were first released in open files of the U.S. Geological Survey 

(Brabb, 1962; Brabb and Churkin, 1964, 1965), and 

one was later revised and published (Brabb and 

Churkin, 1969). A simplified geologic map which 

shows the type area at an approximate scale of 

1:55,000 is in a report by Brabb and Churkin (1967, 

fig. 4). 

ACKNOWLEDGMENTS 

H. J. Roepke and R. N. Passero ably assisted 

Brabb .in 1960 in collecting fossils from the type 

Tahkandit Limestone, measuring sections, and describing the rocks. J. C. Melik and R. L. Taylor in 

1961 and D. L. Giles in 1962 assisted in collecting 

additional Tahkandit fossils. Michael Churkin, Jr., 

of the U.S. Geological Survey joined the project in 

1962, mapped several areas underlain by the Tahkandit Limestone, and collected several Tahkandit fossils. Churkin and E. W. Bamber of the Geological 

Survey of Canada collected from the type section of 

the Tahkandit in 1963. Brabb, Grant, and Bamber, 

along with A. K. Armstrong of the U.S. Geological 

Survey, collected fossils from the type section again 

in 1967. We thank these colleagues for their extensive help and support. Armstrong also kindly identified the fossils shown on the photomicrographs. We 

also extend thanks to S. J. Nelson of the University 

of Alberta and J. T. Dutro, Jr., of the U.S. Geological 

Survey for their assistance. Grant is responsible for 

the identification and age of brachiopods and for 

the sections entitled "Brachiopods from the Tahkandit Limestone" and "Systematic Paleontology." 

l 
2 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

650§6?,00-

0

-' -r----1

-

4

,

1 30_'_----r--.::::::::----=~-=--=--=,-------____.::....:..:::.., 0030 ' 1,000 feet thick, more than three times as thick as 

65°00' 

0 5 l........J 

0 10 

10 15 MILES 

20 KILOMETERS 

+ Sheep 

Mtn. 

FIGURE !.-Location of type section of Tahkandit Limestone. 

PREVIOUS WORK 

Tahkandit, an Indian name for the Nation River, 

was first used by Spurr (1898, p. 169-174) for a 

"series" of limestone, shale, and conglomerate of 

Devonian to "late Carboniferous" (which then included the Permian) age exposed along the upper 

reaches of the Yukon River and its tributaries. 

Spurr's Tahkandit Series included a white limestone 

and basal sandstone and conglomerate referred to as 

the Tahkandit Limestone in this report, the underlying Nation River Formation of Late Devonian age, 

and other rocks as old as Precambrian ( ?) and as 

young as Cretaceous. Mertie (1930, p. 121) restricted 

Spurr's Tahkandit Series to the white limestone and 

basal sandstone and conglomerate of Permian age, 

and he named these rocks the Tahkandit Limestone. 

His report has served until now as the standard 

reference for the Tahkandit at its type locality. 

Nelson (1961a) extended the name Tahkandit Formation to the Ogilvie Mountains, Yukon Territory, 

Canada (fig. 1). The formation there is as much as 

in Alaska. It contains abundant spicular chert and 

siltstone (Bamber and Barss, 1969) not found in 

the formation at its type section, and it overlies formations not recognized in Alaska. There is some 

doubt, therefore, about the appropriateness of the 

name Tahkandit for this formation in the Yukon 

Territory. In a report describing corals from the 

formation, Nelson (1962a) emphasized that assignment of these rocks to the Tahkandit was provisional 

and possibly incorrect. Nelson found fusulinids of 

Permian (Leonard) age in the Yukon Tahkandit, 

and he illustrated some of the characteristic brachiopods. Additional brachiopods from the Tahkandit of 

the Yukon Territory were described and illustrated 

by Nelson (1962b) and Nelson and Johnson (1968). 

Fusulinids also from the Yukon Tahkandit were described and illustrated by Ross (1967) ; Skinner and 

Wilde (1966) reported on fusulinids from a stream 

cobble that could have come from the same formation. Barss (1967) prepared a preliminary report on 

sporomorphs from the Yukon Tahkandit, and Bamber and Barss (1969) described the palynology and 

stratigraphy of this formation in greater detail. The 

present report discusses recent work on the Tahkandit Limestone in Alaska in relation to specific 

stratigraphic and structural problems. 

TYPE SECTION OF THE TAHKANDIT LIMESTONE 

LOCATION 

There is, unfortunately, some ambiguity concerning the location of the type section that Mertie 

(1930) described. He stated (p. 121) 

The type locality is along the Yukon just above the mouth 

of the Nation River * * * where a belt of such rocks crosses 

the Yukon, trending northeast (see pl. lOA). 

The illustration referred to shows prominent outcrops of the Tahkandit Limestone on the northeast 

valley slope of the Yukon River, and Laudon, Hartwig, Morgridge, and Omernik (1966, p. 1874) interpreted these outcrops to be the type section. 

However, Mertie also stated (p. 122) 

The best section is seen along the southwest bank of the 

Yukon, where both the overlying and underlying rocks are 

exposed (see fig. 6). 

Formal stratigraphic language has changed over the 

years, and Mertie's "type locality" and "best section" would now be termed "type area" and "type 

section," respectively. 

The type section designated by Mertie is exposed 

inconspicuously along a narrow slough of the Yukon 

River (figs. 2 and 3) in the northwest corner of sec. 17, 
TYPE SECTION OF THE TAHKANDIT LIMESTONE 

FIGURE 2.- View of slope on southwest side of Yukon River near mouth of Nation River showing location of the slough 

and cliff sect ions, the composite type section of the Tahkandit Limestone. See figure 3 for an enlarged view of the 

slough section and figure 4 for an enlarged view of the cliff section. View southwest. 

FIGURE 3.-Stereogram showing Yukon River slough section of Tahkandit Limestone. Man at 

left is standing on contact between Tahkandit (above) and Nation River (below) Formations. See figure 9 for a view of this contact. Limestone beds forming the rocky points 

at localities 22327-PC and 21794-PC are separated by a covered interval which is 

thought to conceal a fault. Numbers refer to fossil collections and localities described in 

text. View northwest. 

8 
4 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

T. 4 N., R. 30 E., lat 65°10.8' N., long 141°41.9' 

W. (Charley River A-2 quad.). Many of the rocks 

and particularly the overlying Triassic sequence are 

exposed only when the Yukon River is low. In addition, the slough is being filled with silt and gravel, 

so that some of the section observed by Mertie and 

earlier geologists from 1897 to 1930 can no longer 

be seen, even when river level is very low. 

The section along the slough is considered to be 

incomplete and is herein revised so that it includes, 

in addition, the prominent limestone cliff several 

hundred feet upstream (south) (see fig. 2). The 

rocks that have been added to the type section are 

in the vicinity of the numbered localities shown in 

figure 4. In this report the term "slough section" 

will be used to refer to Mertie's type section, "cliff 

section" will be used for the upper part of the revised type section, and "type section" will be used 

for the combined slough and cliff sections. 

One additional refinement of this terminology is 

needed. We believe that the slough section includes 

parts of the Tahkandit Limestone repeated by faulting. These repeated rocks, in the vicinity of locality 

21794-PC (fig. 3), are herein excluded from the revised type section. Figure 5 shows the inferred correlation of this repeated section with the composite 

type section. To summarize, the composite type 

section for the Tahkandit Limestone, as defined 

herein, includes the rocks from the vicinity of localities 21752-PC to 22328-PC in the slough section 

and from localities 21746-PC to 21751-PC in the 

cliff section. 

STRUCTURAL SETTING 

The slough section shown diagrammatically by 

Mertie (1930, fig. 6) is, unfortunately, a mirror 

image of the locality as viewed from the Yukon 

River. We have, therefore, sketched the geology at 

the type section as an observer sees it; the sketch 

(fig. 6) shows the slough and cliff sections and provides an interpretation of the local structure. (See 

also figs. 2-4.) 

FIGURE 4.-Enlarged view of cliff section of Tahkandit Limestone shown in figure 2. Numbers refer to fossil localities described in text. Note the slump or fault block of limestone at lower right. View northwest. 
TYPE SECTION OF THE TAHKANDIT LIMESTONE 

EXPLANATION 

Massive,very pale orange 

~ 

bioclastic limestone 

Sandy and glauconitic 

limestone 

~ L:.d 

~ 

Dark-gray limestone Glauconitic sandstone and 

and shale chert-pebble conglomerate 

G 

Shale Covered 

21750-PC • 

U.S Geological Survey 

fossil collection number 

Composite type section 

3 

Inferred repeated section 

of Tahkandit Limestone showing 

relation of overlying Glenn 

Shale along Yukon River slough 

Limestone and shale 

with fossils of late 

Triassic age 

Fossils of late Triassic 

age collected in 1915 

by Eliot Blackwelder 

and in 1925 by J. B. 

Mertie (1930, p. 130-

135) from shale and 

limestone now covered 

by river silt 

Cliff section 

21751-PC • 21788-PC • 

21750-PC • 

21749-PC • 

21748-PC • 

21747-PC • 

21746-PC • 

Neospirifer cf. N. stria.topctradoxus 

Kuvelous·ia sphiva 

Spiriferella. sp., Mego·usia sp. 

Dinoproductus sp. 

Pterosph·ifer alatu.s 

Spz:rijerella cf. S. keilha.vi 

Waagenoconcha cf. W. irginaejo1··rnis 

Yakm>le1>ia rnarnrnata 

Kuvelousia sphiva 

2 

Slough section 

Wa.agenoconcha cf. 

W. irg·inae 

Spz:rijerellet drasche·i 

22328-PC • 

22327-PC • 

22324-PC • 

23055-PC • 

21758-PC • 

Megousia sp., Sp1:riferelln sp. 

Horridonia. sp. 21794-PC • 

Kuvelou.sia sphiva 

Waagenoconcha. cf. W. irginae 

Yako·vlevia rnarnrnata, Megousia sp. 

Yakovlevia rnammata 21756-PC • .:·.: 23050- PC • ·: ·.:.:. Tharnnosia cf. T. a rctz:m 

D1904A • 

Yakovlevia sp., Megousict sp. 

---UNCONFORMITY ---

Devonian spores 

Devonian spores 

Covered interval 

probably conceals 

a fault 

Wnagenoconchet cf. W. irgina.e 

Kuvelousict sphiva 

Horridonia sp. 

Inferred fault. These rocks 

are structurally above the 

limestone at 22328-PC 

E 

LL.Z 

"t'-<( roaJo. .::! z 

Qio::o 

O.c:> 

::3-.~w -:uo 

z 

400 

300 

200 

100 

0 

FIGURE 5.-Stratigraphic columns of the Tahkandit Limestone in its type section. See table 1 for a more complete list 

of fossils and the text for a description of each Permian and Carboniferous (PC) locality. D-numbers are spore 

samples described by Scott and Doher (1967) and Brabb and Churkin (1967). See figures 2-4 for the locations of 

the columns and figure 6 for the structural setting. 

5 
6 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

chert- pebble conglome rate in Nation River Formation 

0 

VIEW WEST 

Covered 

West bank of 

Yukon River 

Isolated slump or 

fault block of Tahkandit Limestone 

500 

Devonian spores in 

Nation River Formation (sample 

Di940A) 

1000 FEET 

I Slough section (type 

section of Tahkandit 

Limestone of Mertie, 

1930,p. 122) 

\ Devonian spores at 

top of Nation River 

Formation (samples 019408 and 

D1940C) 

APPROXIMATE SCALE 

FIGURE 6.-Sketch of relations between the Tahkandit Limestone (Pt) and the Nation River Formation (Dnr) on the southwest bank of the Yukon River opposite the mouth of the Nation River. Numbers refer to spore samples described by 

Scott and Doher (1967) and Brabb and Churkin (1967). 

We and Mertie assign shale beneath the Tahkandit in the slough section to the Nation River Formation, and we believe that this shale forms an anticline, shown in figure 6. Spores from the shale are 

Devonian and are comparable to spore assemblages 

from the Nation River Formation at other localities 

(Scott and Doher, 1967; Brabb and Churkin, 1967). 

On the other hand, others seem to have overlooked 

the anticline and placed the shale in the middle of 

their so-called Tahkandit Formation (Laudon and 

others, 1966, fig. 5, 1,183-1,414 ft). What we interpret as a slump or fault block (figs. 4 and 6) forms 

the interval from 1,005 to about 1,180 feet in Laudon's Tahkandit section, and it is apparently represented as a synclinal segment in Mertie's diagram 

(1930, fig. 6). 

Still unresolved is the report by Laudon, Hartwig, 

Morgridge, and Omernik (1966, p. 1876-1877; fig. 5) 

of productid brachiopods in a resistant bed of chertpebble conglomerate; although Laudon and his colleagues described the conglomerate as forming the 

Tahkandit Formation (see fig. 6), we believe it is 

well within the Nation River Formation. No brachiopods have ever been found in rocks definitely belonging to the Nation River Formation, and their occurrence in this conglomerate would probably 

require drastic revision of the structural interpretation. In 1967 we searched for these brachiopods with 

A. K. Armstrong and E. W. Bamber, but the only 

fossils we found were the abundant plant fragments 

that also characterize the Nation River Formation 

at other localities. The report of brachiopods in the 

chert-pebble conglomerate seems, therefore, to be 

in error. 

Evidence for the faults shown in the slough section in figure 6 will be discussed in another part of 

this report. 

SANDSTONE UNIT 

Definition and Extent 

The oldest beds of the Tahkandit Limestone in the 

type section as herein revised consist of about 75 

feet of glauconitic sandstone, chert-pebble conglomerate, and sandy and glauconitic limestone. For con-
TYPE SECTION OF THE TAHKANDIT LIMESTONE 7 

venience, these rocks are referred to in this report 

as the sandstone unit. The sandstone unit has not 

yet been recognized outside the type section, but it 

could be present elsewhere and covered by more 

resistant talus from overlying massive limestone 

beds. If subsequent work shows that the sandstone 

unit also occurs in other areas beneath the massive 

limestone that characterizes the Tahkandit, then 

the sandstone unit should be proposed formally as a 

member. 

Lithology 

The sandstone that forms most of the sandstone 

unit is an arenite consisting primarily of fairly angular chert and quartz grains. Calcite is also common, 

and in some of the sandstone it is in the form of 

fossil fragments. Rounded glauconite grains are so 

abundant in some of the sandstone that the rock is 

bright green. 

Seven thin sections were made of the sandstone, 

and in a ff'w of these it appears as though some of 

the chert, quartz, calcite, and glauconite has been 

dissolved and redeposited. Angular authigenic 

quartz commonly coats well-rounded quartz grains. 

The rock is well sorted, as shown in figure 7, but all 

the pore spaces have been filled with these secondary 

minerals. No clay was found in any of the sandstone 

beds. 

The sandstone is generally in beds from a fraction 

of an inch to a few inches thick. Some of the beds 

are a few feet thick. The weathered appearance of 

the beds, shown in figure 3, is blocky and less massive than that of the overlying limestone. 

FIGURE 7.-Photomicrograph of texture of a finegrained sandstone representative of the sandstone 

unit (Joe. 21752-PC; cross-polarized light). Eventextured white, gray, and black grains are chiefly 

quartz; the black and white speckled grains consist 

of chert and calcite. 

Chert-pebble conglomerate and grit are interbedded with the sandstone. The chert dasts are 

gray, green, white, black, and red, and they are 

generally well rounded. Some of the beds have scourand-fill structures. 

The sandstone and conglomerate are about 60 feet 

thick, and they grade vertically upward, near locality 21758-PC (see fig. 3), into about 15 feet of 

thickly bedded sandy and glauconitic limestone. The 

calcite in the limestone consists largely of algal, 

bryozoan, pelmatozoan, and brachiopod fragments 

1-2 mm in maximum dimension, and partly of secondary calcite that has filled spaces between the fossil fragments. This limestone, considered the uppermost bed in the sandstone unit, grades into massive, 

relatively sand- and glauconite-free limestone that 

forms the beautiful pinnacles and cliffs at many 

localities in the vicinity of the Nation River. This 

massive limestone, referred to for convenience as 

the limestone unit, will be described in a later section of the report. 

Fo•sils 

Brachiopods are the most abundant fossils in the 

sandstone unit. They are listed in stratigraphic 

order in table 1 and described in greater detail in the 

systematic paleontology section. They indicate that 

the sandstone unit is of Early Permian age and probably equivalent to the upper part of the Leonard 

Series of the Southwestern United States. Corals 

and foraminifers are fairly common, but they have 

not yet been examined. A gastropod at locality 

21757-PC was examined by E. L. Yochelson who 

determined that it is a new genus (written commun., 

1965). Two samples of glauconitic sandstone from 

the upper part of the sandstone unit were submitted 

for spore and pollen analysis to Richard A. Scott 

who reported (written commun., 1963), 

Collections 60ABa672EA and 60ABa672GA contain trilete 

spores and bisaccate pollen grains, including striate bisaccates typical for Permian time. Some hystrichosphaerids are 

also present suggesting a brackish or marine environment. 

Several collections of pelecypods from the sandstone unit were examined by John Pojeta, ~rr. (written commun., 1965), but few of the fossils were preserved well enough for even generic identification. 

Figure 8 shows a thin section of one of these pelecypods that displays prismatic structure. Similar calcite prisms are the principal constituent of limestones of Permian and Cretaceous age in other regions of Alaska (Brosge and others, 1969), but the 

prisms are scarce in thin sections of the Tahkandit 

Limestone. 
8 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

Brachiopods 

TABLE I.-Brachiopods fr-om the type section of the Tahkandit Limestone 

Measured or inferred distance, in feet above base of unit, of USGS fossil colin. No. 

~ ~ ~ ~ ~ ~ ~ 0 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 0 ~ ~ ~ ~ ~ ~ ~ ~ 0 ~ ~ 0 0 0 0 ...-4 .....I C\1 C\1 C\1 'o::tt ~ '<:1'1 "dd "'d" 'o:tl 1.C 1.C u':) l.t:) 1.0 l(;) IQ C.0 C.0 C.0 t- t- l.t:) ...-4 ...-4 ...-4 C"J t\1 t\1 ('.1 C¢ CQ er,) (!') 0':1 "dd 0') 0 CO "dd lt:l 1.() 

t\1 P"'' .,.....( C\1 C\1 C\1 

- - ------------- --------------- ------ ---------- uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

lO c.o 1.t:1 0') t.t:> ~ ~ 'o:tl lQ O'l 'o:tl 'o:tl an ~.t:~ 1.0 0') -.:t' en 11:1 C\1 I.C I.C 1.0 I.Q C\1 ~ lQ 1.0 lQ C\1 -.:1' c.o C\1 C\1 C\1 1.0 1.0 lQ C\1 a: "dd c.o I.C co 1.0 oo t- t- t- t- t- 0 t- 0 r::- t- 0 0 0 0 t- t- t- t- t- et:1 0 t- 0 0 M t- 0 0 t- CQ t- t- 0':1 CQ et:1 0 0 0 M t- t- 0 t- 0 t- t- .....t ....,. ...-4 ,..... ...-~ CQ ...-4 Cl':l .......~ ...-4 CQ M eo l!'l':l ....-~ ...-~ .......~ .....~ - C\1 CQ ,..... M eo e-.1 - Ct:l e¢ .....t N .....~ .....~ C\1 C\1 e.:~ eo M eo C\1 ...-4 """" ""' .....~ CQ ..... """" C\1 C\1 C\1 C\1 C\1 C\1 C\1 C\1 C\1 e-3 C\1 C\1 C\1 C\1 C\l e-3 C\1 C\1 t\1 C'l t'l C\l C'l C'J c-:1 C\1 C\1 C\1 t\1 t\1 t\1 C"J C\l C\1 C'l t\1 C'l CiJ C\1 C\1 C\1 C\1 C\1 C\1 C\1 C\1 

I I 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I II I I I I I I I I I I I t\1 ~ et:~ 1.0 ~ c.o lco t- 1.0 t-oo 0') o .....t co oo c.o ~ r:- C\1 N oo CQ 'o:tl CQ t- lt':l com~ oo o t.t:> c.o t- r:- oo moo 'o:tl ~ .....~ o C\1 ..... 00 

------------ - ,- ----sa-;;d;;u,;;-;; ;;;;it----- ------ - ------ --um--;.t;;-n-;;-u-;;it- ---- -,--

Anidanthus sp -----;;----------- --X--X-------;;------- - --- ---

gf~!~~11z~~i:~~~~~~~~~~~~~~~~~ tenuissima Gobbett_ _____ ___~~ _____ ~~ ~ =i 

__ =·= ___~~ ________ ~~ ~~ =i ~ _ ~~ _____________ ~ ~~ ~~ ~ ~ :?: __~~ __:~ ______________ =i ~~ ~ ~ ~~ =i :?: ____________ ~~ ~~ ~ ~~ ~~ =i ___~~ ~~ ____~ __

~~ ~~ _____ ~~ :?: _ =i 

__ ~~ __ ~~ __ =i X ~~ ____:~ ~~ _ _ 

Choriatites sp --- - --- - -------- - ______ ___ _ _________ _ ___ _ ____ ________ X ______ __ _____ _ ____ -- -- - - -- -- __ ____ -- -- -- -- -- -- -- - - - - -- Cleiothyridinasp -------------- __ ____ X ____ __ __ X ___ __ _ ____ _______ _ ______ X __ ________ __ __ ____ ______ X ___ _ _________________ _ 

Composita cf. C. ambigua (Sowerby) _________________ _ __ ___ _ __ __ __ __ __ ______________ _____ ______ _ _____ _____ __ ___________________ _ __________ ____ X __ 

Craspedalosia sp -------------- __ __ _________ _ __ __ __ _________ _ __ -- - - -- -- -- - - -- -- -- -- -- -- -- -- -- ? -- -- -- -- -- - - -- -- -- -- -- -- -- -- Crurithyris sp ___ _____ _______ _ 

Derbyia sp ----------- -------- Dielasma cf. D. timanicum :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: -~ :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: : : :: :: :: :: :: -?- :: :: :: :: -x 

(Tschernyschev) ___ ___ ________ _____ ________ ______________ X __ __ ______ __ __ ------ -- -- __ -- - - -- -- -- -- -- -- - - -- -- -- -- -- -- -- -- -- Horridonia sp ---------------- ____ __ X __ __ _______ _ ___ _ ____ ____ X ___ _ -- ______ __ X ? __ __ X X-- X X __ X ___ _ __ X X X __ X------ granulijera (Toula) _________ _ _____ _ ______ ___ ________ _ ________ ___________ _ __ __ __ X ____ ____ ___ ___ __ ______ __ __ ___________ _ 

Hustedia•p - - ---------------- _____ _________ __ ___ __________ _ _____ _ __ __ __ ____ ____ __ ____ ___ _______________ __ -·- ---- __ X ____ X 

Kochiproductus sp ------------- ___ _ -- - - __ -- -- ____ -- -- -- - - -- -- -- - - -- -- -- -- - - -- - - -- -- - - -- -- - - -- -- -- -- -- - - -- -- -- -- -- -- -- -- -- ? Krotovia sp ------------------- __ ____ __ _____ _ __ __ -- __ -- ________ __ ? - - -- -- - - -- - - -- Kuvelousia sphiva Waterhouse ___ __ ____ __ __ ______ ____ __ __ _____ _______________ __ ___ _ :: ::::X X:::: X:: X:::::::: X X:: :: X X X 

cf. K. weyprechti (Toula) _____ _________________ _ __ __ __ __ _______ ___ __ ___ __ ______ __ _ ____ ___ __ _____ ___ _____________ X _____ _ Licharewia sp. _____ __________ __ ___ __ _ __ ______ ___________________ _ ____ __ ____________ ________ _____ _ __________ __ __ _____ _ __ X __ 

Lingula sp ------------------- ______ X ______ ________ - - __ ____ ______ -- ______ ------ -- -- __ -- - - -- -- -- -- - - - - - - -- - - -- -- -- - - - - -- -- cf. L .freboldi Gobbett_ _________ ____ X ______ __ __ ____ __ __ __ ___ ____ _ __ ___ ________ __ _ ______ ____ ____ __ ___ __ __ ___ -- _____ _ ___ _ 

Linoproductus sp --- ----------- _____ _ __ X ____ ________ __ ____ ______ X X X __ X ________ ______ X __ _________ __ _____ ---- __ -- __ X X 

cf. L. dorotheevi (Fredericks) ______________________ __________ _ __ __________________ __ __ ___ _ ___ _ - - ___ _________ __ -- __ -- ___ __ _ 

cf. L . schrencki 

(Stuckenberg) ___ _______ _ Liosotella sp _______ ____ ______ _ 

pseudohorrida (Wiman) ___ _ _ 

Lissochonetes sp ---------------

Martinia sp - - ------------- - -- greenlandica Dunbar_ _____ _ 

Megouaia sp ---- ----- --------- Neochonetes sp ---------- ------ Neospirijer sp ---------------- cf. N. striatoparadoxus 

- - - - -- -- -- -- -- - - -- -- -- -- -- -- -- -- -- - - -- -- -- -- -- X-- -- -- -- -- -- -- -- -- -- -- -- -- -- - - -- -- -- -- -- - - ____ -- __ - - - - __ X ____ -- ____ __ __ __ ------ __ - --- __ -- -- -- __ -- - - -- - - -- -- -- -- -- -- -- -- -- -- - - - - X--

:: :: == :: :~ == :~ :: == :: :: == ~ :: :~ == :: :: :?: :: :~ :: == :: :: :~ :~ :: :~ :~ :~ :~ ~ :: :: : : :: :: :~ :~ :: == :~ :: :: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- X---------- ---- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- X X X X-- X-- -- __ -- - - __ __ X __ X X-- ---- ---- __ X -- -- __ - - X-- X X-- X------ X X---- - --- X X __ X __ -- ___ _ ? -- - - -- -- -- __________ __ X ____ - - -- __ -- -- -- __ X---- X-- -- -------- X X - - -- -- ---- -- - - __ __ -- ___ _ __ __ - - ? -- -- ________ X ---- __ -- _____ _ -- -- -- __ -- -- -- -- -- -- -- -- -- -- X -------- ------

(Toulal--- ----- -------- ____ _________ ___ ___ _ ____ __ _______ _ X ________ ___ ___ -- -- __ -- - - -- -- -- -- -- __ -- -- -- -- -- X-- X-- X 

Odontoapirijer sp - ------------- ___ _ __ __ ____ ___ __ ___ ______ __ ___ _ __ __________ __ __ __ -- -- __ -- -- -- -- -- -- - - - - - - ---- -- -- -- -- -- X- -

Orbiculoidea sp - -- - - ---------- Permophricodothyris sp - - - ------ cf. P. nodoaa (Chao) _____ _ _ 

-- -- X X ________ ______ ____ __ _____ ________ ___ __ __ ___ _____ _____ ____ ____ _ __ __ ___ _ ___________ __ _ 

__ __ X-- X ______ __ __ ____ __ __ X __ ? -- X X __ X ___ _________ __ -- -- X ---- - - ______ X -- X-- X--·----

-- -- -- -- -- -- -- -- -- -- -- -- -- X-- -- -- -------------- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Psilocamarasp --------------- -- ------------ ---- ---- ------------ -- -- ---- -- ------ -------- ---- -- -- - ----- - --- ---- ---- ? - --- -- Pterospirifersp - -------------- ____ ___ _ ____ X __ ______ -- ____ ________ __ __________ - ----- __ X X-------- -- - - -- - ----------------- alatus (Schlotheim) ________ ___ __ _ ___ _ __ ____ ______ -- ______ ____ ______________ ______ __ __ - - -- -- -- -- -- -- - - -- -- -- -- -- -- - - X--

Pulchratia sp --- ------------- - Rhynchopora sp -- - ------------ Schuchertella sp _____ ___ ---- __ _ 

Septacamera cf. S. kutorgae 

? ::X-?- -x X:: -x ::X:::::::::: X:: -x :: X:: :::: :::: X -x :: :: -x X -x X -x X:::::::: -x X X:: -x :: X:: - - - - -- -- -- -- -- -- -- -- -- -- -- -- -- - - -- -- -- -- - - -- -- - - -- -- - - -- - - -- ? - - - - - - -- -- -- -- -- -- -- -- - - -- -- --

(Tschernyschev) __ ____ ______ _ - - - - -------- -- -- -- ---- - - ---- ------ -------- -- -- ---- - - -- -- - - -- -- X-- _______ _____ ___ ______ _ j _ __ _ 

Spiriferella sp ----- ----------- ________ __ -- ____ -- X ___ _ ____ ____ X __ X X- - X-- - - X - - - - ____ - - X X X X-------- X X-------- -- X draachei (Toula) ___________ __ __ __ ___ _ -- ____ _____________ _ __ __ ___ _ -- ____ -- -- -- -- -- -- -- -- X---- ---------------------- ---- cf. S. keilhavi (Buch) _______ -- __ __ -- -- -- -- ____ -- -- -- __ __ -- __ - - -- -- -- -- -- -- -- -- -- -- __ __ -- X ---- -- ------------ ____ X---- -- cf. S . saranae (Verneuil) ___ _ 

Stenoscisma sp - -------- ------- spitzbergiana (Stepanov) __ _ _ 

Thamnosia sp ------ --- ------- cf. T . arctica (Whitfield) ___ _ 

__ __ __ -- - - -- -- -- __ -- __ -- -- X __ __ ____ -- __ - - - - -- -- X -- -- - - -- -- -- -- -- -- - - -- -- -- -- -- -- -- -- - - -- -- -- __ ______ -- __ -- __ -- __ -- ____ __ __ X -- X __ - - __ -- - --- -- -- -- -- - - -- X ------------ X---- -- ---- X --

-- -- -- -- -- -- -- -- -- -- X-- ---- X- - ------ ---- -- ------ -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- ___ _ __ _____ _ __ ___ ____ _ __________________ ____ __ __ __ ____ ____ __ X ____________ ___ _______ X __ ----

-- _ _ ____ _ _ __ ____ -- ? __ X X __ X X __ X X X -- X-- ---- -- -- __ - - -- -- X ------ - - - --------- - --- -- -- -- -- __ -- X ____ X ____ -- __ -- ______ -- __ - --- -- ------ -- X -- -- -- -- -- -- -- X---------- X X X-- X-- X- -

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- X ---- -- -- ---- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Tornquistia sp - - - ------------- Waagenoconcha sp ------ ------ - cf. W . irginae (Stuckenberg) ____ - - ____ -- -- - - -- -- -- -- -- -- -- - - -- -- -- -- -- -- -- -- - - -- -- -- ? X -- X -------------- X-- X - - ------ cf. W. irginaejormia 

(Stepanov) _________ ____ ____ -- -- -- -- - - -- -- -- -- -- -- -- - - ____ -- __ -- -- -- -- -- -- -- -- -- -- -- -- -- - - -- -- -- -- -- -- -- -- X---- ---- y akovlevia mammata (Keyser ling) ___ _________ ___ _ 

Brachiopods, not examined ____ _ 
TYPE SECTION OF THE TAHKANDIT LIMESTONE 9 

FIGURE 8.-Photomicrograph of calcarenite about 65 

feet above the base of the sandstone unit (Joe. 

21758- PC; cross-polarized light). The pelecypod 

shell that displays prismatic structure in the center 

of the photograph could be confused with Inoce1·amus 

sp., of Mesozoic age. Small bryozoan fragments are 

also common in this thin section. 

Structures similar to Zoophycos sp. of Hantzchel 

(1962, p. W219, fig. 137), the so-called Spirophyton 

sp. of various authors, are common in the sandstone 

unit. They were first noted by Mertie (1930, p. 122) 

and later described as slump structures by Laudon, 

Hartwig, Morgridge, and Omernik (1966, fig. 5, at 

1,450 ft on their stratigraphic column). The structures are widely distributed in rocks of Pennsylvanian and Permian age in the Yukon Territory 

(Nelson, 1961b, p. 35), and they are generally accepted to be of organic origin but of uncertain 

affinity. 

Relation to Underlying Nation River Formation 

Mertie (1930, p. 120) and Laudon, Hartwig, Morgridge, and Omernik (1966), in the belief that the 

sandstone unit grades into the underlying Nation 

River Formation, proposed elaborate structural explanations for the occurrence of the Nation River 

Formation structurally below the Calico Bluff Formation of Carboniferous age in other areas (see 

discussion by Brabb and Churkin, 1967). In 1962 

Churkin dug out the contact between the oldest beds 

of the sandstone unit and the youngest beds of the 

underlying Nation River Formation (fig. 9) and 

discovered a 6-inch-thick layer of bluish-gray clay 

that he interpreted to be a paleosol. A fault-gouge 

origin for this clay was also considered, but no evidence for a fault contact was found. Furthermore, 

the clay has a uniform texture and does not show 

any evidence of fracturing or shearing; it is plastic 

when wet, as are many clay deposits of sedimentary 

origin. Richard A. Scott analyzed spores and pollen 

in samples from the clay (D1940C), from the uppermost shale beds of the Nation River Formation 

(D1904B), from the shale about 75 feet below the 

top of the Nation River Formation (D1904A), and 

from the shale of the Nation River Formation at 

several other localities and he determined that the 

samples are all Devonian. The age and character of 

the spore assemblage were documented by Scott 

and Doher (1967). Their report, together with data 

from regional mapping, formed the basis for the 

reports by Churkin and Brabb (1965) and Brabb 

and Churkin (1967) in which the age of the Nation 

River Formation was revised from Pennsylvanian ( ?) to Late Devonian. Inasmuch as the sandstone 

unit of the Tahkandit is Early Permian, an unconformity representing all the Carboniferous and part 

of the Upper Devonian and Permian separates the 

basal beds of the sandstone unit from the top of the 

underlying Nation River Formation. 

The sandstone unit of the Tahkandit has no clay, 

and it is better sorted and has far more calcite and 

glauconite than sandstone beds in the underlying 

Nation River Formation. The nearly ubiquitous occurrence of plant fragments in the Nation River 

Formation and of brachiopods in the Tahkandit 

Limestone are even more helpful in distinguishing 

these rock units. 

FIGURE 9.- Contact (dashed line) between the Tahkandit 

Limestone and the Nation River Formation in the slough 

section. Plastic clay at the top of the Nation River F ormation is probably a paleosol. The clay is underlain by 

thinly laminated shale. 
10 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

LIMESTONE UNIT 

Lithology 

The limestone unit consists predominantly of algal, bryozoan, pelmatazoan, foraminiferal, and 

brachiopod fragments 1-2 mm in maximum dimension and partly of secondary ( ?) calcite that has 

filled the spaces between the fossil fragments. Figures 10 and 11 show the representative texture and 

lithology. Chert, quartz, and glauconite grains are 

minor but pervasive constituents. Rapid rock analyses of three samples (loc. 21749-PC, 21747-PC, and 

22325- PC) from the limestone show that the CaO 

plus C02 content is 96.2, 96.3, and 96.6 percent respectively, and that the MgO content is less than 1 

percent. Acid insoluble residues of several additional 

limestone samples help confirm that the limestone 

unit is nearly pure calcium carbonate. 

No bedding was observed in the limestone, but 

there are several widely spaced and parallel partings 

that could be an expression of subtle changes in 

lithology or, more likely, sheeting joints parallel to 

bedding. No bedded chert was found in the limestone 

unit at the type section or at nearly all other exposures, but a few thin beds of pale brown chert 

were observed at the top of the limestone unit about 

a mile northeast of the cliff section. 

Fossils 

Brachiopods are abundant throughout the limestone unit; they are described in another section of 

this report. Algal, bryozoan, pelmatazoan, and foraminiferal fragments are common, and at locality 

FIGURE 10.-Photomicrog raph of bioclastic limestone in 

the Tahkandit Limestone (loc. 21760-PC) showing 

broken and abraded fossils cemented by sparry calcite. The sievelike fra gments are parts of echinoderms, and most of the other pieces are parts of 

bryozoans. 

21751-PC arenaceous foraminifers are abundant in 

insoluble residues of the limestone. A few corals 

were observed or collected at nearly every locality. 

REPEATED SECTION 

The Tahkandit Limestone structurally above the 

limestone unit near locality 22327- PC in the slough 

section (see fig. 3 and fig. 5,-col. 2), is considered to 

be repeated by faulting. This inferred repeated section is shown in figure 5 (col. 3). The idea of a 

faulted and repeated section is supported by a similar stratigraphic sequence-from sandstone to sandy 

and glauconitic limestone to fairly pure limestone in 

both the slough section (col. 2) and the inferred 

repeated section (col. 3)-and by the similarity of 

faunas at locality 21794- PC to faunas in the lower 

part of the limestone unit in the slough and cliff 

sections. 

Tahkandit beds in the upper part of the cliff section (fig. 5, col. 1) are not exposed in the corresponding part of the inferred repeated section. They 

could be covered by river silt, but it is more likely 

that these rocks have been faulted above river level 

and removed by erosion. 

CORRELATION OF CLIFF SECTION AND SLOUGH SECTION 

Nearly all the sandstone unit is concealed beneath 

talus in the cliff section, so it was difficult to determine the stratigraphic position of the cliff section 

with respect to the slough section. A few sandy and 

glauconitic limestone and sandstone beds in the vicinity of locality 21746-PC are considered to be 

FIGURE 11.-Photomicrog raph of bioclastic limestone 

characteristic of the limestone unit of the Tahkandit 

Limestone (Joe. 21748-PC) in the cliff section. The 

largest sievelike fragment is from an echinoderm, 

the chambered shell in the center is a for aminifer, 

and most of the other pieces are from bryozoans. 
TAHKANDIT LIMESTONE AT OTHER LOCALITIES 11 

uppermost beds of the sandstone unit. They are 

overlain by a massive, relatively pure limestone like 

that in the lower part of the limestone unit in the 

slough section. The sections are correlated, therefore, by similar lithology and similar sequence. 

RELATION TO OVERLYING GLENN SHALE 

The Tahkandit Limestone is overlain by the Glenn 

Shale, a newly named formation of Middle Triassic 

to Early Cretaceous age (Brabb, 1969, p. 113). In 

the inferred repeated section (fig. 5, col. 3), however, the oldest fossils that have yet been found in 

the Glenn Shale are Late Triassic (Norian), according toN. J. Silberling (see Brabb, 1969, p. 112). The 

contact between the Glenn Shale and Tahkandit 

Limestone is not exposed wherever the formations 

have been recognized, so the stratigraphic and 

structural relations between the formations are uncertain. 

THICKNESS 

The composite type section (fig. 5) indicates that 

the sandstone unit is about 75 feet thick and the 

limestone unit about 270 feet; thus, the total thickness of the type Tahkandit is about 345 feet. This 

thickness is substantially less than the 527 feet reported by Mertie (1930, p. 123), but part of his 

section is considered to be repeated by faulting. The 

thickness is far less than the 2,065 feet reported by 

Laudon, Hartwig, Morgridge, and Omernik (1966, 

fig. 5), but their section includes parts of the Nation 

River Formation and parts of the Tahkandit repeated by faulting or slumping or both. 

SUMMARY 

1. Mertie's (1930) type section for the Tahkandit 

Limestone is incomplete and faulted. A supplementary section is added to Mertie's section so 

as to include the entire formation. 

2. The type section proposed by Laudon, Hartwig, 

Morgridge, and Omernik (1966) includes infolded and improperly assigned parts of the underlying Nation River Formation, as well as 

slumped(?) and faulted parts of the Tahkandit 

that they interpreted to be a continuous stratigraphic sequence. 

3. The total thickness of the Tahkandit is about 

345 feet, not the 527 feet reported by Mertie 

(1930, p. 123), nor the 2,065 feet reported by 

Laudon, Hartwig, Morgridge, and Omernik 

(1966, fig. 5). 

4. An unconformity separates the Tahkandit from 

the underlying Nation River Formation. 

TAHKANDIT LIMESTONE AT OTHER LOCALITIES 

The Tahkandit Limestone has been recognized and 

mapped in a 900-square-mile area of east-central 

Alaska, principally in the vicinity of the Nation 

River and its tributaries (Brabb and Churkin, 1969). 

In this area it consists of massive, very pale orange 

or light- to dark-gray limestone containing abundant 

brachiopods. Glauconite and chert grains are common but not conspicuous. 

The thickness of the Tahkandit outside the type 

section nowhere exceeds 300 feet. At most localities, 

only a few tens of feet of the formation are exposed. 

Brachiopods from the Tahkandit Limestone outside the type section are listed in table 2. The localities from which these fossils were collected are 

described on pages 18-21. 

BRACHIOPODS FROM THE TAHKANDIT LIMESTONE 

AGE 

Brachiopods are the most abundant fossils in the 

Tahkandit Limestone and, in the absence of fusulinids or other fossils convenient for age determination, provide the basis for correlation with other 

formations in the nearby Yukon Territory (Nelson, 

1961a; Ross, 1967; Bamber and Barss, 1969) and 

elsewhere (this paper). The Tahkandit brachiopods 

represent an Arctic fauna that permits close correlation with Permian faunas throughout the Arctic, including those of the type Permian of the Soviet 

Union. They also provide an estimate of the relative 

age of the fauna in terms of the North American 

provincial series based on sections in the Southwestern United States. 

The brachiopods suggest that the age of the Tahkandit is Early Permian and probably spans the 

interval from late Leonard to early Guadalupe. In 

terms of the Texas section, this implies correlation 

with the Lower Permian Road Canyon and Word 

Formations (Cooper and Grant, 1966). Arctic Permian brachiopods are long ranging, however, so 

correlations across such a great distance and span of 

latitude must be considered approximate at best. 

Correlation among Arctic units is somewhat more 

satisfactory because similar faunas can be compared over shorter distances, although it is still 

difficult to estimate precise equivalency among 

faunas consisting of long-ranging species. Correlation with other Arctic units that contain fusulinids 

or ammonoids provides an alternative method of 
12 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

correlation with the Texas section. As will be explained, brachiopods of the sandstone unit of the 

Tahkandit seem to accord best with those of the 

Assistance Formation in the Canadian Arctic Archipelago. The Assistance, in turn, is considered to be 

latest Leonard in age (Nassichuk and others, 1965; 

VVaterhouse, 1968). 

Brachiopods from the limestone unit of the Tahkandit indicate a slightly younger age and a closer 

relationship to the central east Greenland fauna 

described by Dunbar (1955). This sequence has been 

previously considered very Late Permian (for example, Permian Subcommittee, 1960; Nassichuk and 

others, 1965) largely because of presence of the 

ammonoid Cyclolobus. Dutro (1961) presented a correlation chart for the Arctic Permian, which stated 

·explicitly that the east Greenland beds are not latest 

Permian. Recent evidence suggests that the range 

of Cyclolobus begins earlier in the Permian and corroborates the opinion that the east Greenland fauna 

is older than hitherto believed (Grant, 1968). 

The fauna of the limestone unit is certainly not 

identical with the east Greenland fauna, but it does 

contain elements of that fauna (as will be explained) 

that suggest an age slightly younger than that of 

the sandstone unit of the Tahkandit. On this rather 

tenuous basis, an early Guadalupe (that is, VVord) 

age is indicated. 

The area of Permian outcrop nearest to the Tahkandit type section is in the Ogilvie Mountains, just 

across the border in the Yukon Territory, Canada 

(Nelson, 1961a). The best section is on the Tatonduk 

TABLE 2.-Brachiopods from the Tahkandit Limestone outside the type section 

[Stratigraphic position uncertain] 

USGS fossil colln. No. 

Brachiopods 
BRACHIOPODS FROM TAHKANDIT LIMESTONE 13 

River (see fig. 1), 30 airline miles from Nation, 

Alaska. This section was described by Bamber and 

Barss (1969), who applied the name Tahkandit Formation to the uppermost unit; this unit had been 

dated by Ross (1967) as Leonard in age on the basis 

of fusulinids from the lower part of the unit. It is 

tempting to accept the Tahkandit of the Yukon Territory as the direct equivalent of the Tahkandit in 

Alaska, especially owing to the similar sequencea lower clastic unit and an upper carbonate unit. In 

detail, however, the sequence in Canada is rather 

different from the type Tahkandit and much thicker. 

The Permian section along the Tatonduk River 

amounts to about 4,000 feet, and the part called 

Tahkandit is more than 1,000 feet thick (Bamber 

and Barss, 1969, p. 5). The glauconitic lower part of 

the Tahkandit in the Yukon Territory, is 280 feet 

thick and contains Leonard fusulinids (Bamber and 

Barss, 1969, p. 6, 7), whereas the sandstone unit of 

the type Tahkandit is only about 75 feet thick, and 

no fusulinids have been found in it. The upper unit 

of the Tahkandit in Canada is mainly chert and dolomite, and only minor amounts of the kind of biogenic 

limestone that makes up the bulk of the limestone 

unit in the type section in Alaska are present. 

Despite these lithic differences, however, the 

brachiopod faunas are similar (Nelson, 1961a) and 

probably correlative. Thus, the Leonard age of the 

fusulinids in the Canadian rocks equivalent to the 

lower unit indirectly suggests the age of the type 

Tahkandit, especially as a Leonard (albeit late Leonard) age is indicated also by the brachiopods for the 

sandstone unit in the type section. 

BRACHIOPODS FROM THE SANDSTONE UNIT 

The lowermost 75 feet of the Tahkandit Limestone 

-sandstone conglomerate and sandy and glauconitic 

limestone-contains a brachiopod fauna more similar 

to that of the Assistance Formation of the Canadian 

Arctic Archipelago than that of central east Greenland. Brachiopods, some of which are illustrated in 

this report, are : 

Arctitreta cf. A kempei (Andersson) 

Calliprotonia? sp. 

Cancrinella sp. 

Chonetina cf. C. superba Gobbett 

Choristites sp. 

Cleiothy1·idina sp. 

Craspedalosia sp. 

Dielasma cf. D. timanicum (Tschernyschev) 

K rotovia sp. 

Kuvelousia cf. K. weyp1·echti (Toula) 

Lingula cf. L. freboldi Gobbett 

Linoproductus sp. 

Linoproductus cf. L. schrencki ( Stuckenberg) 

426-210 0- 71- 2 

Liosotella pseudohorrida (Wiman) 

Lissochonetes sp. 

M artinia sp. 

N eochonetes sp. 

Odontospirifer sp. 

Orbiculoidea sp. 

Permophricodothyris cf. P. nodosa (Chao) 

Pterospirifer sp. 

Rhynchopora kochi Dunbar 

Spiriferella cf. S. saranae (Verneuil) 

Stenoscisma spitzbergiana ( Stepanov) 

Striatijera sp. 

Thamnosia cf. T. arctica (Whitfield) 

Tornquistia sp. 

Waagenoconcha cf. W. irginae (Stuckenberg) 

Yakovlevia mammata (Keyserling) 

BRACHIOPODS FROM THE LIMESTONE UNIT 

The upper 270 feet of the Tahkandit Limestonepredominantly white limestone-contains a large 

brachiopod fauna similar in most respects to that of 

the lower unit but lacking or nearly lacking some 

species such as Thamnosia cf. T. arctica and having 

a few additional species that suggest somewhat closer 

affinities to the central east Greenland fauna. Kochiproductus and abundant Horridonia and Kuvelousia 

sphiva indicate a slightly younger age for this part 

of the Tahkandit Limestone, perhaps correlative to 

part of the Foldvik Creek Formation of central east 

Greenland or to one or both of the unnamed formations above the Assistance Formation in the Canadian Arctic Archipelago (Nassichuk and others, 

1965; Waterhouse, 1968). Brachiopods from this 

part of the Tahkandit Limestone, some of which are 

illustrated in this report, are: 

Arctitreta cf. A. kempei (Andersson) 

Cancrinella sp. 

cf. C. tenuissima Gobbett 

Cleiothy1·idina sp. 

Composita cf. C. ambigua (Sower by) 

Derbyia sp. 

Hor1·idonia granulifera (Toula) 

Hustedia sp. 

K ochiproductus sp. 

Kuvelousia sphiva Waterhouse 

Licharewia sp. 

Linoproductus sp. 

Liosotella pseudohorrida (Wiman) 

Lissochonetes cf. L. spitzbergiana (Toula) 

Megousia sp. 

N eochonetes sp. 

Neospirifer cf. N. striatoparadoxus (Toula) 

Odontospirifer sp. 

Pe1·mophricodothyris sp. 

Pterospirifer alatus ( Schlotheim) 

Rhynchopora kochi Dunbar 

Septacamera cf. S. kutorgae (Tschernyschev) 

Sp,iriferella draschei (Toula) 

Stenoscisma sp. 
14 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

Tornquistia sp. 

Waagenoconcha cf. W. irginaeformis (Stepanov) 

Yakovlevia mamrnata (Keyserling) 

The brachiopods that are illustrated (pis. 1 and 

2) are discussed briefly below, in the order of the 

Treatise on Invertebrate Paleontology, part H, 

(Moore, 1965). Suprageneric categories are given 

only to provide the reader with necessary clues for 

easy recognition of the group to which each species 

belongs ; the genera are arranged alphabetically 

within each of these categories. 

SYSTEMATIC PALEONTOLOGY 

Family SCHUCHERTELLIDAE Williams, 1953 

Genus ARCTITRETA Whitfield, 1908 

Arotitreta of. A. kempei (Andersson) 

Plate 2, figures 21, 22, 25 

Species of this streptorhynchoid brachiopod are 

common in many Arctic Permian faunas. Wiman 

(1914), for example, devoted several plates to illustrations of shells of this type (which he designated 

as species of Streptorhynchus) from Spitsbergen and 

indicated that they are extremely abundant there. 

The common type having the wide hinge is A. kempei, 

similar to the very few specimens that have been 

found in the limestone unit of the Tahkandit Limestone. 

The name A rctitreta has remained essentially unused since it was proposed by Whitfield (1908) for 

the poorly preserved species A. pearyi from Cape 

Sheridan, Ellesmere Island. More recently, the name 

Grumantia was proposed by Ustritskii (in Ustritskii 

and Chernyak, 1963, p. 70) for Streptorhynchus 

kempei, a well-documented species whose interior 

features are known. Study of Whitfield's figures and 

plaster casts of the types of A. pearyi, however, 

against the background of some familiarity with 

Arctic Permian brachiopods, leaves very little doubt 

that the genus Arctitreta encompasses "Grumantia" 

kempei. A. pearyi probably is conspecific with Streptorhynchus triangularis Wiman. 

Family CHONETIDAE Bronn, 1862 

Genus CHONETINA Krotov, 1888 

Chonetina? of. C. superba Gobbett 

Plate 1, figure 37 

This large chonetid resembles the one illustrated 

by Gobbett (1963, pl. 15, fig. 2-6) from the Brachiopod Chert of Svalbard in its large size, quadrate outline, very weakly costellate surface, and shallow 

sulcus. From all accounts, however, these shells bear 

little resemblance to C. artiensis Krotov, the type 

species (see for example, Muir-Wood, 1962, pl. 5, fig. 

9-12 for illustrations of the type). These large 

chonetids are fairly common in the sandstone unit 

of the Tahkandit Limestone. 

Genus LISSOCHONETES Dunbar and Condra, 1932 

Lissoohonetes of. L. spitzbergiana (Toula) 

Plate 2, figures 15-17 

This is one of several chonetids in the Tahkandit 

Limestone. It is characterized by a tiny and entirely 

smooth shell having a shallow median fold. It occurs 

in the upper unit of the formation, along with a very 

large species of Chonetina? (pl. 1, fig. 37). Another 

chonetid, not illustrated here, intermediate in size 

between L. cf. L. spitzbergiana and Chonetina? cf. C. 

superba and having the faint costellation of a species 

of N eochonetes, is locally very abundant in the glauconitic beds of the sandstone unit. 

Superfamily PRODUCTACEA Gray, 1840 

Genus THAMNOSIA Cooper and Grant, 1969 

Thamnosia of. T. arotioa (Whitfield) 

Plate 1, figures 37-39, 45 

This large productid is one of the more common 

brachiopods in Arctic Permian faunas and is 

similarly abundant in the Tahkandit Limestone. It 

has been placed in several genera since Whitfield 

(1908) designated it as a species of Productus. Gobbett (1963, p. 91) assigned it to Costiferina MuirWood and Cooper, but it seems to have little in common with C. indica (Waagen), the type species. 

Cooper and Grant (1969, p. 10) established the genus 

Thamnosia for a group of species from the Leonard 

and Word Formations that includes forms closely 

similar to the Arctic shells. The specific name is applied tentatively because it is suspected that the 

name "arctica" included more than one species, but 

no comparative study was undertaken to confirm 

this. This species occurs in both units of the Tahkandit but seems to be limited to the sandstone unit 

and only the lower part of the limestone unit. 

Genus CANCRINELLA Frederiks, 1928 

Canorinella sp. undet. 

Plate 1, figures 31, 32; plate 2, figures 18, 19 

One or more species of Cancrinella are present but 

not particularly abundant in most collections from 

both units of the Tahkandit. Some beds in the sandstone unit have considerable accumulations of these 

shells; for example, the silty limestone bed 66 feet 

above the base that contains the two specimens illustrated on plate 1 is essentially e Cancrinella 

coquinite. 
SYSTEMATIC PALEONTOLOGY 15 

Genus HORRIDONIA Chao, 1927 

Horridonia granulifera (Toula) 

Plate 1, figures 46, 47 

Productus hm·ridus Sowerby var. granuliferus Toula, 1875, 

p. 232, pl. 6, fig. 3a-c. 

Ho1·ridonia timanica Gobbett (not Stuckenberg), 1963, p. 94, 

pl. 10, fig. 1-4. 

H mTidonia granulije1·a ( Toula) Logan, 1966, p. 206, fig. 2 

(for discussion and full synonymy). 

H orridonia is one of the characteristic brachiopods of the Arctic Permian and probably for that 

reason has been split into many species. Logan 

(1966) presented an analysis of Horridonia and 

combined many of the species. His interpretation of 

the common Arctic Horridonias is followed here: 

H. granulifera lacks cardinal and auricular spines on 

the ventral valve. 

H orridonia granulifera is abundant in the Tahkandit Limestone, except in the lower part of the 

sandstone unit. It is especially abundant just above 

the sandstone unit, in the basal part of the limestone unit where some beds are Horridonia coquinites. 

Genus LIOSOTELLA Cooper, 1953 

Liosotella pseudohorrida (Wiman) 

Plate 1, figures 1-5, 18-20 

Productus pseudohorridus Wiman, 1914, p. 74, pl. 17, fig. 

1-11. 

Liosotella pseudohon·ida (Wiman) Gobbett, 1963, p. 62, 

pl. 3, fig. 27-34 (for full synonymy). 

The name of this species is well chosen because ' at first glance it resembles a very small example of 

H orridonia. It is characterized by a deep sulcus in 

the v.entral valve and rather sharp ventral flanks, 

especially on exfoliated specimens. The ventral beak 

is sharply pointed and costation is very weak; the 

beak is smooth, lacks rugae, and the costae are 

weakest there. There are only a few spines ; one on 

each side of the venter, two or three on each flank 

proximal to the ears, and some small spine bases 

a~ong the margin that may be the remnants of juvenile attachment spines. This also is one of the more 

abundant brachiopods in the Tahkandit Limestone· 

it occurs in both units. ' 

Genus KUVELOUSIA Waterhouse, 1968 

Kuvelousia sphiva Waterhouse 

Plate 2, figures 1-4, 11, 25 

Kuvelousia sphiva Waterhouse 1968, p. 1175, pl. 154, fig. 

14-20; pl. 155, fig. 1-21.' 

This species is larger and smoother than either 

Kuvelousia cf. K. weyprechti (Toula) or species of 

Megousia in the Tahkandit Limestone. The ornamentation consists of weak costellae and growth lines; 

the sulcus is fairly deep, and the shell outline is 

somewhat quadrate. The dorsal valve is thick, especially toward the anterior margin, and the extended 

ears are rather wide and blunt in contrast to the 

slender ear extensions in M egousia. This is one of 

the most abundant brachiopods in the limestone unit 

of the Tahkandit. 

Kuvelousia cf. K. weyprechti (Toula) 

Plate 1, figure 21 

This species is smaller, wider, and more strongly 

costate than K. sphiva. The sulcus of the ventral 

valve is variable-as deep as in K. sphiva in some 

specimens and very shallow in others. This shell 

most nearly resembles those assigned to K. weyprechti by such authors as Wiman (1914), Frebold 

(1937), and Gobbett (1963), but full study of the 

fauna is necessary before it can be identified confidently. 

Genus MEGOUSIA Muir-Wood and Cooper, 1960 

Megousia sp. undet. 

Plate 2, figures 5-10 

This species is larger than the type species of 

M egousia from Texas but nevertheless is a rather 

small shell. It is smaller and proportionately somewhat wider than species of Kuvelousia, but its main 

distinction is its thin and flexuous dorsal valve with 

longer and narrower ears than in K uvelousia. It is 

fairly common throughout the formation but is not 

so abundant as K uvelousia. 

Genus LINOPRODUCTUS Chao, 1927 

Linoproductus cf. L. schrencki (Stuckenberg) 

Plate 1, figures 40, 41 

Specimens of Linoproductus are common throughout the Tahkandit Limestone, but they are largest 

and most abundant in the sandstone unit. A large 

species having a wide hinge and tapered anterior 

margin resembles L. schrencki in these features, although it differs in lacking the anterior fold or 

swelling of the ventral valve that is so obvious in 

L. schrencki (see Tschernyschev, 1902, pl. 27, fig. 1; 

Ustritskii and Chernyak, 1963, pl. 12, fig. 4-7). This 

species lacks the flattened or squarish ventral visceral area of so many species of Linoproductus, 

such as L. dorothewvi (Frederiks) in Gobbett (1963, 

pl. 11, fig. 2). 
16 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

Genus WAAGENOCONCHA Chao, 1927 

Waagenooonoha of. W. irginae (Stuokenberg} 

Plate 1, figures 42-44 

This species is characterized by normal convexity 

for a species of Waagenoconcha, in contrast to the 

very flat form that has been designated W. cf. W. 

irginaeformis (Stepanov). In addition, it is narrower 

than that species and has a deeper sulcus that is 

expressed as a fold in the dorsal valve, whereas in 

TiV. cf. W. irginaeformis the sulcus of the ventral 

valve is so shallow that it is expressed only as a 

slight emargination of the dorsal valve. This species 

occurs in the sandstone unit of the Tahkandit Limestone. 

Waagenooonoha of. W. irginaeformis (Stepanov} 

Plate 2, figures 23,24 

This proportionately flat and wide species is rather 

rare in the limestone unit of the Tahkandit, but a 

few valves or identifiable fragments occur in most 

collections. It is not very similar to Stepanov's 

(1937, pl. 6, fig. 4, 5) species (also illustrated by 

Tschernyschev, 1902, pl. 52, fig. 2-4), but the name 

is employed here simply for contrast with the more 

typical form of Waagenoconcha exemplified by W. 

cf. W. irginae. 

Genus YAKOVLEVIA Frederiks, 1925 

Yakovlevia mammata (Keyserling} 

Plate 1, figures 9-12, 33-36 

Productus mammatus Keyserling, 1846, p. 206, pl. 4, fig. 

5a-b. 

Muirwoodia mammata (Keyserling) Gobbett, 1963, p. 112, 

pl. 13, fig. 23-28 (for full synonymy}. 

The very sharp geniculation of the ventral valve 

distinguishes this species from most other species of 

Yakovlevia, such as Y. impressa (Toula), Y. duplex 

(Wiman), or Y. greenlandica (Dunbar). It has the 

four spines that characterize the genus (formerly 

known as Muirwoodia): one projects posterolaterally 

on each ear, and one diverges anteriorly from the 

other on each anterior surface. Most specimens have 

only the bases of these spines. 

This is one of the most common and typical brachiopods of the Tahkandit Limestone. It occurs in 

both units throughout the section. 

Order RHYNCHONELLIDA Kuhn, 1949 

Superfamily RHYNCHONELLACEA Gray, 1848 

Family TETRACAMERIDAE Likharev, 1958 

Genus SEPTACAMERA Stepanov, 1937 

Septaoamera of. S. kutorgae (Tsohernysohev} 

Plate 2, figure 20 

Species of Septacamera are found in most Arctic 

Permian formations and are abundant in some. 

Septacamera is very rare in the Tahkandit Limestone 

but is mentioned here to document its occurrence as 

a consistent member of the Arctic Permian fauna. 

Superfamily STENOSCISMATACEA Oehlert, 1887 

Genus STENOSCISMA Conrad, 1839 

Stenosoisma spitzbergiana (Stepanov} 

Plate 2, figures 29-33 

Camerophoria spitzbergania Stepanov, 1937, p. 157, 182, 

pl. 9, fig. 11; Gobbett, 1963, p. 125, pl. 16, fig. 4-9. 

CamerozJhoria biplicata Frebold (not Stuckenberg), 1950, 

p. 67, pl. 16, fig. 3-3a. 

Stenoscismataceans are abundant in most Arctic 

Permian faunas but are rare in the Tahkandit Limestone. This species has the shape and costation of 

Stepanov's species from Spitsbergen, in contrast to 

S. kochi Dunbar or the other species from east 

Greenland identified by Dunbar (1955). The salient 

features are the trigonal outline, subdued convexity, 

three prominent costae on the fold, and weak costae 

on the flanks. Steno.cwisma is in both units of the 

Tahkandit Limestone. 

Superfamily RHYNCHOPORACEA 

Muir-Wood, 1955 

Genus RHYNCHOPORA King, 1865 

Rhynohopora of. R. koohi Dunbar 

Plate 1, figures 22-26 

Rhynchopora kochi Dunbar, 1955, p. 114, pl. 19, fig. 7-24. 

Rhynchopora is ubiquitous in Arctic Permian 

faunas. The Tahkandit shells most nearly resemble 

Dunbar's species from east Greenland in size, shape, 

and costation although, as Harker and Thorsteinsson 

(1960, p. 64) remarked, that species is very close to 

R. nikitini var. arctica Likharev and Einor (1939). 

The Tahkandit shells have the weaker costation that 

characterizes R. kochi; it is fairly abundant throughout the section, and there are at least a few specimens in nearly every sample. 
SYSTEMATIC PALEONTOLOGY 17 

Order SPIRIFERIDA Waagen, 1883 

Superfamily SPIRIFERACEA King, 1846 

Genus NEOSPIRIFER Frederiks, 1919 

Neospirifer cf. N. striatoparadoxus (Toula) 

Plate 2, figures 12-14 

This is the common form that most workers in 

the Arctic Permian designate under the name 

"Spirifer." Its fasciculate costation distinguishes it 

as a species of Neospirifer, a genus ubiquitous in the 

Permian. It is a consistent but nowhere abundant 

constituent of both units of the Tahkandit Limestone. 

Genus SPIRIFERELLA Tschernyschev, 1902 

Spiriferella draschei (Toula) 

Plate 2, figures 26-28, 34, 35 

Spi'rifer draschei Toula, 1875, p. 239, pl. 7, fig. 4a-c. 

SzJiriferella draschei (Toula) Gobbett, 1963, p. 154, pl. 20, 

fig. 7 (for full synonymy). 

Species of Spiriferella are abundant in most Arctic 

Permian faunas, and the Tahkandit fauna is no exception. Large shells and separated valves make up 

coquinites in some beds in the upper unit, and the 

genus also is abundant in the lower unit. Some samples, however, lack Spiriferella entirely, so its occurrence must be considered sporadic despite its 

great local abundance. More than one species occurs 

in the Tahkandit Limestone, but only two are illustrated as examples. This one accords very well 

with Toula's (1875, pl. 7, fig. 4a-c) and Wiman's 

(1914, pl. 3, fig. 2-26) illustrations of S. draschei 

from Spitsbergen and Bear Island. 

Spiriferella cf. S. saranae (Verneuil) 

Plate 1, figures 13-17 

A complete juvenile shell is illustrated as an example of a species of Spiriferella other than S. 

draschei; it most nearly resembles shells that normally are assigned to S. saranae, for example by 

Tschernyschev and Stepanov (1916), Likharev and 

Einor (1939), Harker and Thorsteinsson (1960), 

and Gobbett (1963). It has proportionately broader 

and fewer costae than S. draschei, is less strongly 

convex, and has only a few costae in the sulcus rather 

than the abundantly costate sulcus of S. draschei. 

Family RETICULARIACEA Waagen, 1883 

Genus MARTINIA M'Coy, 1844 

Martinia sp. undet. 

Plate 1, figures 27-30 

Examples of M artinia, rare in the Tahkandit 

Limestone, have been found only in the sandstone 

unit. This smooth and empty shell apparently lacks a 

fold and thus is different from M. greenlandica 

Dunbar, which is abundant in the east Greenland 

fauna. It most nearly resembles Martinia sp. A of 

Gobbett (1963, pl. 21) from the Lower Gypsiferous 

Series of Svalbard. That series is Carboniferous in 

age, so the resemblance probably results from the 

essential featurelessness of these shells. 

Genus PERMOPHRICODOTHYRIS Pavlova, 1965 

Permophricodothyris cf. P. nodosa {Chao) 

Plate 1, figures 6-8 

This species is characterized by its rather strong 

convexity, proportionately long dorsal beak, and its 

distinct and regularly spaced growth laminae that 

are fringed by the bases of tiny spines and set off 

from one another by a very shallow groove around 

the anterior edge of each lamina. Of described 

species it most nearly resembles Squamularia nodosa 

Chao (1929, p. 95, pl. 11, fig. 4-6) from the Loping 

Series of Kiangsi, China. 

The name Permophricodothyris was introduced by 

Pavlova (1965, p. 133) for Permian shells that 

previously had been called N eophricadothy1·is Likharev, a genus that she considers synonymous with 

Phricodothyris George. Permophricodothyris (this 

or other species) is not abundant in the Tahkandit 

Limestone, but most san1ple8 have a few specimens. 

It occurs in both units. 

LOCALITY DESCRIPTIONS FOR PERMIAN FOSSIL 

COLLECTIONS FROM EAST-CENTRAL ALASKA 

The identification and location of Permian fossils 

collected in east-central Alaska prior to 1937 were 

published by Mertie (1930, p. 125-129; 1933, p. 431-

432; 1937, p. 148-152). More recent collections of 

Permian fossils from the Step Conglomerate, a lateral facies of the Tahkandit Limestone in the upper 

Nation River area, were identified by R. E. Grant 

and listed by Brabb (1969, p. 19). Table 3 completes 

the description of Permian fossil localities between 

the abandoned settlement of Nation (see fig. 1) and 

the United States-Canada boundary. 
18 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

TABLE 3.-Locality desc1·iptions for Permian fossil collections from east-central Alaska 

USGS fossil 

colin. No. 

USGS field 

loc. No. Description of locality 

Slough section 

Stratigraphic position 

and lithology 

Collector and year 

of collection 

[Charley River A-2 quad., 1956 ed. All fossils from Tahkandit Limestone in place ; listed in stratigraphic order from oldest to youngest, 

unless otherwise noted] 

21752-PC .............. 60ABa672A ............ Lat 65°10.8' N., long 141 °41.9' W.; 

21769-PC .....•......•. 60ABa672B 

21753-PC •.....••••.•.. 60ABa672C 

21795-PC •.......•.•••. 60ABa672CB 

21754-PC .•......••.... 60ABa672D ........... . 

23046-PC .............• 67A2+22 

21796-PC .........•.... 63ACn2831 ............ . 

23047-PC ........•••... 67A2+40 

21755-PC ......•..•.•.. 60ABa672E 

21797-PC .•....•.••.•.. 60ABa672E 

23048-PC •............. 67 A2+45 

23049-PC ........•..•.. 67A2+47 .............. 23050-PC .............. 67A2+49 .............. 23051-PC .............. 67A2+53 ·············· 21756-PC . ... . .. .. .... . 60ABa672F ............ 

21798-PC ........•..•.• 60ABa672F ............ 

21799-PC .............. 63ACn2332 ............ 21757-PC . .. . .. . .. ... . . 60ABa672G ············ 

22322-PC ......••...••. 60ABa672G ............ 

23052-PC .............. 67A2+60 

21758-PC .............. 60ABa672H ........... . 

23053-PC .............. 67A2+66 

23054-PC .............. 67 A2+71 

southwest bank of Yukon River 

along slough. 

.... do .... 

.... do .... 

.... do .... 

. ... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .. .. 

. . . . do ... . 

.... do .. .. 

.... do .... 

. ... do .... 

. . . . do ... . 

.... do ... . 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

. .. . do .... 

About 5 ft stratigraphically above 

base of sandstone unit ; from 

fine-grained sandstone. 

About 2 ft above 60ABa672A ; from 

pebbly sandstone. 

About 7 ft above 60ABa672B ; from 

glauconitic sandstone. 

About 17 ft above base of sandstone unit, 

About 7 ft above 60ABa672C; beneath a 1-ft-thick chert-pebble 

conglomerate bed; from glauconitic sandstone. 

Close to 60ABa672D ; about 22 ft 

above base of sandstone unit. 

About 8 ft stratigraphically above 

60ABa672D and 29 ft above base 

of sandstone unit ; from sandstone. 

About 40 ft above base of sandstone unit. 

About 44 ft above base of sandstone unit. 

Additional material . 

Close to 60ABa672E, about 45 ft 

above base of sandstone unit. 

2 ft above 67A2+45 . 

2 ft above 67A2+47 . 

4 ft above 67A2+49; near or at 

60ABa672F. 

About 53 ft above base of sandstone unit. 

Additional material . 

About 4 ft above 60ABa672F. 

About 59 ft above base of sandstone unit. 

Additional material. 

60 ft above base of sandstone unit . 

About 65 ft above base of unit; 

from calcareous and glauconitic 

~;andstone. 

About 66 ft above base of unit . 

About 71 ft above base of sandstone unit. 

H. J. Roepke, 1960. 

Do. 

Do. 

Michael Churkin, Jr., 

1963. 

H. J. Roepke. 1960. 

R. E. Grant, E. W. 

Bamber, A. K. Armstrong, and E. E. 

Brabb, 1967. 

Michael Churkin, Jr .. 

1963. 

R. E. Grant, E. W. 

Bamber, A. K. Armstrong, and E. E. 

Brabb, 1967. 

H. J. Roepke, 1960. 

Michael Churkin, Jr., 

1963. 

R. E. Grant, E. W. 

Bamber, A. K. Armstrong, and E. E. 

Brabb, 1967. 

Do. 

Do. 

Do. 

H. J. Roepke, 1960 . 

Michael Churkin, Jr., 

1963. 

Do . 

H. J. Roepke, 1960 . 

Michael Churkin, Jr., 

1963. 

R. E. Grant, E. W. 

Bamber, A. K. Armstrong, and E. E. 

Brabb, 1967. 

H. J. Roepke, 1960. 

R. E. Grant, E. W. 

Bamber, A. K. Armstrong, and E. E. 

Brabb, 1967. 

Do . 
LOCALITY DESCRIPTIONS FOR PERMIAN FOSSIL COLLECTIONS 19 

TABLE 3.-Locality descriptions for Pe1·mian fossil collections from east-central Alaska-Continued 

USGS fossil 

colin. No. 

USGS field 

loc. No. Description of locality 

22323-PC .............. 63ACn2341 ............. Lat 65°10.8' N., long 141°41.9' W.; 

23055-PC .............. 67 A2+79-81 ............ 

23056-PC .............. 67A2+85 ·············· 21759-PC .............. 60ABa672K ············ 

22324-PC . . . . . . . . • . . • . . 60ABa672K ............ 

21760-PC . . . . . . . . . . . . . . 60ABa672J ············ 

22325-PC . . . . . . . . . . . . . . 60ABa672J ............ 

22326-PC . . . . .. . .. .. . . . 60ABa672J (float) ..... 

22327-PC . . . . . . . . . . . . . . 63ACn2342 ············· 

23057-PC . . . . . . . .. . .. . . 67A2+105 ············· 

23058-PC . . . . . . . . . . . . . . 67A2+106 ············· 23059-PC . . . . . . . . . .. .. . 67A2+110 ············· 

22328-PC ........•..•.. 60ABa672J A ......•.... 

southwest bank of Yukon River 

along slough. 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

.... do .... 

. ... do .... 

21794-PC .............. 63ACn2781A ........... Lat 65°10.8' N., long 141°41.9' W.; 

southwest bank of Yukon River 

along slough. About 100 ft north 

and downstream from 67A2+110. 

Cliff section 

21751-PC .............. 60ABa1212A ........... Lat 65°10.7' N., long 141°42' W.; 

21788-PC .............. 63ACn2351 ............• 

23062-PC .............. 67A3-15 and 

21750-PC and 

21751-PC. 

67A3-13. 

60ABa1212B 

23061-PC ........•..•.. 67A3-150 

uppermost part of cliff section on 

southwest valley slope of Yukon 

River, a few hundred feet upstream from the slough section 

described above (see figs, 3, 4, 

and 5, col. 1) . 

.... do .... 

. . . . do .... 

.... do .... 

.... do .... 

Stratigraphic position 

and lithology 

About 73 ft above base and 1 ft 

below top of sandstone unit. 

From sandy and glauconitic 

limestone. 

From limestone beds 79-81 ft above 

base of Tahkandit Limestone; 

5-7 ft above top of sandstone 

unit and base of limestone unit. 

4-6 ft above 67 A2+79-81. 

About 16 ft above base of limt>-

stone unit. 

Additional material. 

About 23 ft above base of limestone unit ; from massive pebbly 

limestone. 

Additional material. 

Same locality but material not in 

place. 

From 23 to 27 ft above base of 

limestone unit. 

About 31 ft above base of limestone unit and 105 ft above base 

of Tahkandit Limestone. 

1 ft above 67A2+105. 

4 ft above 67A2+106; 36 ft above 

base of limestone unit and 110 

ft above base of Tahkandit Limestone. This sample is the youngest that can be collected in continuous sequence. 

At or close to 67A2+110. From 

limestone. 

From limestone unit ; inferred to 

be repeated section; probably 

about the same level stratigraphically as 67A2+110. Underlying sandstone unit (see fig, 5, 

col. 3) measured at 1 in.=5 ft 

by H. J. Roepke in 1960, but 

these rocks were covered in 1963. 

Fossils from limestone unit, 1-15 ft 

below apparent top of unit. From 

massive limestone. 

At or close to 60ABa1212A. From 

massive limestone. 

At or close to 60ABa1212A. From 

massive limestone. 

About 95 ft below apparent top of 

limestone unit; from massive 

limestone (see fig. 4) . 

About 150 ft below apparent top of 

limestone unit ; from massive 

limestone. 

Collector and year 

of collection 

Michael Churkin, Jr., 

1963. 

R. E. Grant, E. W. 

Bamber, A. K. Armstrong, and E. E. 

Brabb, 1967. 

Do. 

H. J. Roepke, 1960. 

Michael Churkin, Jr., 

1963. 

H. J. Roepke, 1960. 

Michael Churkin, Jr., 

1963. 

Do. 

Do. 

R. E. Grant, E. W. 

Bamber, A. K. Armstrong, and E. E. 

Brabb, 1967. 

Do. 

Do. 

Michael Churkin, Jr., 

1963. 

Do. 

E. E. Brabb, R. N. 

Passero, and H. J. 

Roepke, 1960. 

Michael Churkin, Jr., 

and E. W. Bamber, 

1963. 

R. E. Grant, E. W . 

Bamber, A. K. Armstrong, and E. E. 

Brabb, 1967. 

E. E. Brabb, R. N. 

Passero, and H. J. 

Roepke, 1960. 

R. E. Grant, E. W. 

Bamber, A. K. Armstrong, and E. E. 

Brabb, 1967. 
20 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

TABLE 3.-Locality descriptions for Permian fossil collections from east-central Alaska-Continued 

USGS fossil 

colin. No. 

USGS field 

loc. No. DeEcription of locality Stratigraphic position 

and lithology 

21749-PC .............. 60ABa1212C ..........• Lat 65°10.7' N., long 141°42' W.; About 160 ft below apparent top 

of limestone unit ; from massive 

limestone. 

21748-PC .............. 60ABa1212D .......... . 

21747-PC .............. 60ABa1212E .......... . 

23060-PC .............. 67A3-265 

21746-PC .............. 60ABa1212F .......... . 

uppermost part of cliff section on 

southwest valley slope of Yukon 

River, a few hundred feet upstream from the slough section 

described above (see figs. 3, 4, 

and 5, col. 1). 

.... do .... 

.. .. do .... 

.... do .... 

. ... do .... 

About 240 ft below apparent top of 

limestone unit ; from massive 

limestone. 

About 265 ft below apparent top of 

limestone unit, from massive 

limestone, 2 ft above contact with 

underlying sandy and pebbly 

limestone inferred to be uppermost beds of sandstone unit. 

At or close to 60ABa1212E. 

About 20 ft stratigraphically below and 50 ft north of 60ABa1212E: 18 ft below inferred top 

of sandstone unit: from sandy 

and pebbly limestone and a 4-in.-

thick glauconite bed. 

Near mouth of Nation River 

23082-PC .............. 67A4-200 .............. Lat 65°11.6' N., long 141°40.3' W.: From limestone unit, visually esti· 

mated to be 200 ft below apparent top. From massive limestone. 

23089-PC .............. 67 ABa162 

23083-PC .............. 67A4-200 (float) 

23086-PC and 

23085-PC. 

67ABa161 

23084-PC .............. 67 A4-250 

from massive limestone cliffs on 

northeast valley slope of Yukon 

River. 

.... do .. .. 

.... do .. .. 

.... do .... 

.... do .... 

Same locality as 67A4-200. 

Collection from talus in the VICinity of 67 A4-200. Limestone . 

.... do .... 

About 50 ft stratigraphically below 67 A4-200 : from massive 

limestone. 

East of Nat ion River 

Collector and year 

of collection 

E. E. Brabb, R. N. 

Passero, and H. J. 

Roepke, 1960. 

Do • 

Do. 

R. E. Grant, E. W. 

Bamber, A. K. Armstrong, and E. E. 

Brabb, 1967. 

E. E. Brabb, R. N. 

Passero, and H. J. 

Roepke, 1960. 

R. E. Grant, E. W. 

Bamber, and A. K. 

Armstrong, 1967. 

E. E. Brabb, 1967. 

Do. 

Do. 

Do . 

[Charley River B-1 quad., 1956 ed. All fossils from Tahkandit Limestone in place, unless otherwise noted: stratigraphic position uncertain] 

22346-PC .............. 63AGs102 .............. Lat 65°17.3' N., long 141°19.6' W. 

22345-PC .............. 63ABa3541 ............. Lat 65°17.4' N., long 141°17.1' W. 

22347-PC .............. 63AGs121 .............. Lat 65°19.0' N., long 14P12.4' W.; 

southwest valley slope of Waterfall Creek. 

22348-PC .............. 63AGs124 .............. Lat 65°18.8' N., long 141 °11.5' W. 

22349-PC .............. 63AGs131A ..........•. Lat 65°18.8' N., long 141°11.4' W.: 

22350-PC .............. 63AGs131B 

along Waterfall Creek about 100 

ft northeast of 63AGs124. 

.... do .... 

22342-PC .............. 63ACn1683 ............. Lat 65°27.0' N., long 141°02.1' W.; 

along spur north of Ettrain 

Creek. 

22343-PC .............. 63ACn1684 ............. Lat 65°27.0' N., long 141 °02.1' W.; 

about 300 ft north of 63ACn1683 : 

elev about 2,200 ft. 

From limestone talus. 

From thick-bedded limestone. 

From coarse-grained very pale 

orange limestone. 

From extensively folded and faulted fine-grained gray limestone 

along Waterfall Creek. 

From faulted light-colored lime-

~tone. 

From dark-colored limestone and 

chert a few feet stratigraphically 

below 63AGs131A, 

Near base of pebbly limestone 

and chert-pebble conglomerate 

mapped as Step Conglomerate by 

Brabb and Churkin ( 1969). 

From limestone and chert-pebble 

conglomerate mapped as Step 

Conglomerate by Brabb and 

Churkin ( 1969). 

D. L. Giles, 1963. 

E. E. Brabb, 1963. 

D. L. Giles, 1963. 

Do. 

Do. 

Do. 

Michael Churkin, Jr., 

1963. 

Do. 
LOCALITY DESCRIPTIONS FOR PERMIAN FOSSIL COLLECTIONS 

TABLE 3.-Locality descriptions for Permian fossil collections from east-central Alaska-Continued 

USGS fossil 

colin. No. 

USGS field 

loc. No. Description of locality 

22344-PC .............. 63ACn1692 ............. Lat 65°27.3' N., long 141°02.4' W.; 

elev about 2,300 ft. 

Stratigraphic position 

and lithology 

From limestone and chert-pebble 

conglomerate mapped as Step 

Conglomerate by Brabb and 

Churkin (1969). 

Between Nation and Kandik Rivers 

Collector and year 

of collection 

Michael Churkin, Jr., 

1963. 

21 

[Charley River B-1 and B-2 quad., 1956 ed. Fossils all from Tahkandit Limestone, but the formation is so extensively faulted that the stratigraphic 

position of the collection is uncertain] 

21742-PC .............. 60ABa561A ............ Lat 65°23.4' N., long 141°26.0' W.; 

from base of cliff on west valley 

slope of Nation River. 

21745-PC .............. 60ABa614 .............. Lat 65°18.9' N., long 141°38.1' W.; 

east valley slope of unnamed 

tributary to Nation River; elev 

about 1,300 ft; northernmost of 

two limestone spurs. 

21744-PC .............. 60ABa614A ............ Lat 65°18.9' N., long 141°38.1' W. 

217 43-PC .............. 60ABa614B ....•.....•. .... do .... 

22332-PC .............. 63ACn2171 ............• Lat 65°20.8' N., long 141°38.7' W.; 

elev about 2,500 ft. 

22331-PC ..........•... 63ACn2156 ............ Lat 65°20.9' N., long 141 °38.9' W.; 

elev about 2,200 ft. 

22340-PC ••........•... 63ACn2113 ..••.•..•••. Lat 65°20.6' N., long 141°43.8' W.; 

along crest of ridge; elev about 

2,900 ft. 

22329-PC .............. 63ACn2121 ............. Lat 65°20.4' N., long 141°43.8' W.: 

along crest of ridge about 1,200 

ft south of 63ACn2113. 

22330-PC .............. 63ACn2124 .....•......• Lat 65°20.2' N., long 141°43.7' W.; 

about 1,500 ft south of 63ACn2121. 

22334-PC .......•..•... 63ACn2051 ......•..••.. Lat 65°20.0' N., long 141 °47.0' W.; 

elev about 2,900 ft. 

22335-PC .............. 63ACn2085 ............. Lat 65°19.5' N., long 141°50.1' W.; 

elev about 2,500 ft. 

22338-PC .............. 63ACn2131 ......•...•.. Lat 65°19.8' N., long 141°45.8' W.; 

elev about 2, 700 ft. 

22339-PC ..........•... 63ACn2132 ........•.... Lat 65°18.5' N., long 141°43.2' W.; 

near spot elev 2,815 ft. 

22336-PC .............. 63ACn2143 ............. Lat 65°18.3' N., long 141°41.4' W.: 

elev about 2,000 ft. 

22341-PC ...........•.. 62ACn1072 ............. Same locality as 63ACn2085. 

21793-PC .............. 63ABa3832 .......•...•• Lat 65°19.3' N., long 141 °45.8' W.: 

elev about 2,300 ft. 

Thinly bedded dark-gray limestone. 

From thickly bedded olive-gray 

limestone. 

From more coarsely grained limestone than at 60ABa614. 

About 15 ft stratigraphically below 60ABa614A and 30 ft stratigraphically above the oldest limestone beds exposed. From massive limestone. 

Near the apparent top of the limestone. 

Limestone beds here form north 

flank of syncline ; those at 63-

ACn2171 form south flank. 

Limestone. 

From sandy and pebbly limestone. 

From the top of a 30-ft cliff of 

limestone. The limestone beds at 

63ACn2113, 63ACn2121, and 63-

ACn2124 seem to be in repeated 

fault slivers separated by argillite of probable Cambrian age. 

From sandy and pebbly limestone. 

From massive limestone. 

From limestone. 

.... do ..•. 

From oil-stained limestone. 

From massive limestone. 

From limestone. 

Miscellaneous locality 

21741-PC .............. 61ABa1881 ............. Lat 65°08.8' N., long 141°52.3' W.; 

Charley River A-2 quad.; south 

bank of Fourth of July Creek. 

From very pale orange Tahkandit 

Limestone. 

E. E. Brabb, R. N. 

Passero, and H. J. 

Roepke, 1960. 

Do. 

E. E. Brabb, R. N. 

Passero, and H. J. 

Roepke, 1960. 

Do. 

Michael Churkin, Jr., 

1963. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Michael Churkin, Jr., 

1962. 

E. E. Brabb, 1963. 

E. E. Brabb, J. C. 

Melik, and R. L. 

Taylor, 1961, 
22 STRATIGRAPHY, PALEONTOLOGY, TAHKANDIT LIMESTONE, EAST-CENTRAL ALASKA 

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Gobbett, D. J., 1963, Carboniferous and Permian brachiopods 

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Logan, A., 1966, The Upper Paleozoic productoid brachiopod 

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INDEX 

[Italic page numbers indicate both major references and descriptions] 

Page 

A 

Acknowledgments ------------------ 1 

alatus, Pterospirifer ---------------- 8, 13 

Algal fragments ------------------ 7, 10 

ambigua, Composita --------------- 8, 13 

Anidanthus sp. -------------------- 8 

arctica, Rhynchopora nikitini ________ 16 

Thamnosia ----------- 8, 12, 13, 14; pl. 1 

Arctitreta kempei ---------- 12, 13, 14; pl. 2 

pearyi ------------------------ 14 

sp --------------------------- 12 

Arenite -------------------------- 7 

artiensis, Chonetina ----------------

Assistance Formation, Canadian Arctic 

Archipelago ------------

Attenuatella sp 

B 

14 

12 

8 

biplicata, Camerophoria ------------- 16 

Brachiopods ------------ 1, 2, 6, 7, 9, 10, 11 

Bryozoans ------------------------ 7, 10 

c Calcite 7, 9 

Calico Bluff Formation --------------

Calliprotonia sp ------------------- 8, 13 

Camerophoria biplicata ------------- 16 

spitzbergiana ------------------ 16 

Cancrinella ----------------------- 14 

tenuissima -------------------- 8, 13 

sp -------------- 8, 12, 13, 14; pl. 1, 2 

Chert ----------------------- 2, 7, 10, 11 

Chert-pebble conglomerate ----------- 6, 7 

Chonetina ------------------------- 14 

artiensis ---------------------- 14 

superba -------------- 12, 13, 14; pl. 1 

sp --------------------------- 12 

Choristites sp --------------------- 8, 13 

Cleiothyridina sp ---------------- 8, 12, 13 

Composita ambigua ---------------- 8, 13 

Corals -------------------------- 2, 7, 10 

Costi!erina ----------------------- 14 

indica ------------------------ 14 

Craspedalosia sp ------------------- 8, 13 

Crurithyris sp --------------------- 8 

Cyclolobus ------------------------ 12 

D 

Derbyia grandiB ------------------- 12 

sp ------------------------- 8, 12, 13 

Dielasma timanicum ---------------- 8, 13 

dorotheevi, Linop1·oductus ----------- 8, 15 

draschei, Spirifer ------------------ 17 

Spiriferella --------- 8, 12, 13, 17; pl. 2 

duplex, Yakovlevia ----------------- 16 

F 

Faulting ------------------------- 4, 11 

Foldvik Creek Formation, 

east Greenland ---------- 13 

Foraminifers ----------------- 2, 7, 10, 13 

freboldi, Lingula ------------------ 8, 13 

G 

Glauconite ------------------- 7, 9, 10, 11 

Glenn Shale ----------------------- 11 

grandis, Derbyia ------------------ 12 

granulifera, Horridonia _______ 13, 15; pl. 1 

granuliferus, Productus horridus ______ 15 

greenlandica, Martinia ------------- 8, 17 

Yakovlevia -------------------- 12, 16 

Grumantia ----------------------- 14 

kempei ----------------------- 14 

Page 

H 

Horridonia ----------------------- 15 

granulifera -------------- 13, 15; pl. 1 

timanica ---------------------- 12, 15 

sp --------------------------- 8, 12 hon·idus granuliferus, Productus _____ 15 

Hustedia sp ---------------------- 8, 13 

Hystrichosphaerids -----------------

impressa, Yakovlevia --------------- 16 

indica, Costdera ------------------- 14 

Introduction ----------------------

irginae, Waagenoconcha __ 8, 12, 13, 16; pl. 1 

i1·ginaefonnis, Waagenoconcha _ 8, 14, 16; pl. 2 

K 

keilhavi, Spiriferella --------------- 8, 12 

kempei, Arctitreta -------- 12, 13, 14; pl. 2 

Grumantia ----------------·---- 14 

Streptorhynchus ---------------- 14 

kochi, Rhynchopora ________ 12, 13, 16; pl. 1 

Stenoscisma ------------------- 16 

Kochiproductus sp --------------- 8, 12, 13 

Krotovia sp -------------------- 8, 12, 13 

kutorgae, Septacamera ______ 8, 13, 16; pl. 2 

Kuvelousia ------------------------ 15 

sphiva ----,----------- 8, 13, 15; pl. 2 

weyprechti ---------- 8, 12, 13, 15; pl. 1 

L 

Leonard Series, Southwestern 

United States -----------

Licharewia sp ------------------ 8, 12, 13 

Lingula freboldi ------------------- 8,13 

sp --------------------------- 8 

Linoproductus --------------------- 15 

dorotheevi -------------------- 8, 15 

schrencki -------------- 8, 13, 15; pl. 1 

sp ------------------------- 8, 12, 13 

Liosotella proboscides -------------- 12 

pseudohorrida _______ 8, 12, 13, 15; pl. 1 

sp --------------------------- 8 

Lissochonetes spitzbergiana __ 12, 13, 14; pl. 2 

sp. ------------------------ 8, 12, 13 

Locality descriptions ---------------- 17 

M 

mammata, Muirwoodia -------------- 16 

Yakovlevia __________ 8, 13, 14, 16; pl. 1 

mammatus, Productus -------------- 16 

Martinia greenlandica -------------- 8, 17 

sp. A ------------------------ 17 

sp -------------------- 8, 13, 17; p. 1 

Megousia ------------------------- 15 

sp ---------------- 8, 12, 13, 15; pl. 2 

Mertie, J. B., quoted --------------- 2 

Muirwoodia -----------------------

mammata 

N 

Nation, Alaska 

16 

16 

13, 17 

Nation River ------------------ 1, 2, 7, 11 

Nation River Formation ________ 2, 6, 9, 11 

Neochonetes ---------------------- 14 

sp -------------------------- 8, 12, 13 

NeophricadothyriN ----------------- 17 

Neospirifer ----------------------- 17 

striatoparadoxus ________ 8, 13, 11; pl. 2 

sp --------------------------- 8, 12 

nikitini arctica, Rhynchopora ________ 16 

nodosa, Permophricodothyris __ 8, 13, 17, pl. 1 

Sqnamularia ------------------- 17 

Page 

0 

Odontospirifer sp ---------------- 8, 12, 13 

Ogilvie Mountains, Yukon Territory, 

Canada ---------------- 2, 12 

Orbiculoidea sp -------------------- 8, 13 

p 

Paleosol -------------------------- 9 

payeri, Waagenoconcha ------------- 12 

pearyi, Arctitreta ------------------ 14 

Pelmatozoans --------------------- 7, 10 

Permophricodothyris ---------------- 17 

nodosa ---------------- 8, 13, 17; pl. 1 

sp ------------------------- 8, 12, 13 

Phricodothyris -------------------- 17 

Plant fragments ------------------- 6, 9 

Pojeta, John, Jr., written 

communication --~-------

Pollen 7. 9 

Previous work on Tahkandit 

Limestone -------------- :1 

proboscides, Liosotella -------------- 12 

Productus ------------------------ 14 

horridus granuliferus ------------ 15 

mammatus -------------------- 16 

pseudohorridus ----------------- 15 

Psilocamara sp -------------------- 8 

pseudohorrida, Liosotella __ 8, 12, 13, 15; pl. 1 

pseudohorridus, Productus ----------- 15 

Pterospirifer alatus ---------------- 8, 13 

sp --------------------------- 8, 13 

Pulchratia sp ----------------------

Q 

Quartz --------------------------- 7, 10 

R 

Rhipidomella sp ------------------- 12 

Rhynchopora --------------------- 16 

kochi ---------------- 12, 13, 16; pl. 1 

nikitini arctica ---------------- 16 

sp --------------------------- 8. 12 

Road Canyon Formation, Tex -------- 11 

s saranae, Spiriferella -------- 8, 13, 17; pl. 1 

schrencki, Linoproductus ____ 8, 13, 15; pl. 1 

Schuchertella sp ------------------- 8 

Scott, Richard A., written 

communication ---------- 7 

Septacamera ---------------------- 16 

kutorgae -------------- 8, 13, 16; pl. 2 

Siltstone ------------------------- 2 

Slough section of Tahkandit Limestone _ 10 

Slump structures ------------------ 9, 11 

sphiva, Kuvelousia --------- 8, 13, 15; pl. 2 

Spirifer -------------------------- 17 

draschei ---------------------- 17 

Spiriferella ----------------------- 17 

draschei ------------ 8, 12, 13, 17; pl. 2 

keilhavi ---------------------- 8. 12 

saranae --------------- 8, 13, 17; pl. 1 

sp --------------------------- 8, 12 

Spirophyton sp _______ -------------

spitzbergiana, Camerophoria --------- 16 

Lissochonetes _________ 12, 13, 14; pl. 2 

Stenoscisma ------------ 8, 13, 16; pl. 2 

Spores --------------------------- 6,9 

Spurr, J. G., quoted ---------------- 2 

Squanwlaria nodosa ---------------- 17 

Stenoscisma 

kochi 

16 

16 

spitzbergiana ---------- 8, 13, 16; pl. 2 

sp ------------------------- 8, 12, 13 

25 
PLATE 1 

[See p, 18-21 for locality descriptions] 

FIGURES 1-5, 18-20. Liosotella pseudohon·ida (Wiman). 

1-4. Silicified ventral valve. Ventral, posterior, side, and interior views, X 1, USGS loc. 

23052-PC, sandstone unit, 60 feet above base. 

5. Dorsal valve interior, calcareous, X 1, USGS loc. 21751-PC, at top of limestone unit. 

18-20. Calcareous shell, partially exfoliated, posterior, ventral, and side views, X 1, USGS loc. 

23055-PC, at base of limestone unit. 

6-8. Pe1·mophricodothyc;·is cf. P. nodosa (Chao). 

Nearly complete shell, partially silicified, X 1, USGS loc. 23051-PC, sandstone unit, 53 feet 

above base. 

9-12, 33-36. Yakovlevia mammata (Keyserling). 

9-12. Silicified shell. Dorsal, ventral, anterior (showing spine bases), and side views, X 1, 

USGS loc. 23051-PC, sandstone unit, 53 feet above base. 

33-36. Sicilified shell. Ventral, dorsal, anterior, and side views, X 1 (hinge ends showing spine 

bases), USGS loc. 23051-PC, sandstone unit, 53 feet above base. 

13-17. Spi'riferella cf. S. saranac (Verneuil). 

Juvenile shell. Dorsal, ventral, posterior, side, and anterior views, X 1, USGS loc. 23051-PC, 

sandstone unit, 53 feet above base. 

21. Kuvelousia cf. K. weyprechti (Toula). 

Ventral valve, ventral view, X 1, USGS loc. 22331-PC, Tahkandit Limestone. 

22-26. Rhynchopora kochi Dunbar. 

Complete shell. Dorsal view, X 2 and X 1, side, anterior, and ventral views, X 1, USGS loc. 

22332-PC, Tahkandit Limestone. 

27-30. Ma1·tinia sp. undet. 

Silicified ventral valve. Interior views, X 1 and X 2, side and ventral view, X 1, USGS loc. 

23050-PC, sandstone unit, 49 feet above base. 

31, 32. Cancrinella sp. undet. 

Two calcareous shells, ventral views, X 1, USGS loc. 23053-PC, sandstone unit, 66 feet above 

base. 

37. Chonetina? cf. C. superba Gobbett. 

Large ventral valve having spines. Ventral view, X 1, USGS loc. 23085-PC, lower part of limestone unit. 

38, 39, 45. Thamnosia cf. T. at·ctica (Whitfield). 

38, 39. Broken silicified shell. Side and ventra] views, X 1, USGS loc. 23049-PC, sandstone unit, 

47 feet above base. 

45. Smaller shell. Dorsal view, X 1, USGS loc. 23050-PC, sandstone unit, 49 feet above 

base. 

40, 41. Linoproductus cf. L. scht·encki ( Stuckenberg). 

Medium-size ventral valve. Side and ventral views, X 1, USGS loc. 23054-PC, top of sandstone 

unit. 

42-44. Waagenoconcha cf. W. irginae (Stuckenberg). 

Partially exfoliated shell. Dorsal, ventral, and side views, X 1, USGS loc. 21743-PC, Tahkandit 

Limestone. 

46, 47. Hm·t·idonia granulifera (Toula). 

46. Calcareous ventral valve, partially exfoliated, ventral view, X 1, USGS loc. 23055-PC, limestone unit. 

47. Calcareous ventral valve, slightly exfoliated, oblique view, X 1, USGS loc. 23055-PC, base 

of limestone unit. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 703 PLATE I 

FOSSILS FROM THE TAHKANDIT LIMESTONE 
PLATE 2 

[See p. 18-21 for locality descriptions) 

FIGURES 1-4, 11. Kuvelousia sphiva Waterhouse. 

1. Shell having part of right ear. Dorsal view, X 1, USGS loc. 23062-PC, limestone unit, 15 feet 

below top. 

2-4. Partially exfoliated shell. Ventral, posterior, and side views, X 1, USG.S Joe. 23062-PC, limestone unit, 15 feet below top. 

11. Dorsal valve. Interior oblique view, X 1, showing part of ear and thickness of valve at anterior, USGS Joe. 21788- PC, limestone unit, about 15 feet below top. 

5-10. Megousia sp. undet. 

5. Slightly exfoliated ventral valve. Ventral view, X 1, USGS Joe. 21794-PC, limestone unit, 

about 35 feet above base. 

6, 7. Somewhat wider ventral valve. Posteroventral and oblique views, X 1, USGS Joe. 21794-PC, 

limestone unit, about 35 feet above base. 

8. Dorsal valve. Interior view, X 1, USGS Joe. 21794-PC, limestone unit, about 35 feet above 

base. 

9. Dorsal valve. Interior view, X 2, showing anterior rim, cardinal process, and median septum, USGS Joe. 21794-PC, limestone unit, about 35 feet above base. 

10. Dorsal valve. Interior view, X 2, showing anterior rim and much of right ear, USGS loc. 

21794- PC, about 35 feet above base. 

12-14. Neospirifer cf. N. striatoparadoxus (Toula) . 

Shell almost completely exfoliated. Dorsal, anterior, and side views, X 1, USGS Joe. 23062-PC, limestone unit, 13-15 feet below top. 

15-17. Lissochonetes cf. L. spitzbergiana (Toula). 

Small complete shell. Dorsal view, X 2, ventral views, X 1 and X 2, USGS Joe. 23083-PC, lower 

part of limestone unit. 

18, 19. Cancrinella sp. undet. 

Almost entirely exfoliated ventral valve. Side and ventral views, X 1, USGS Joe. 21794-PC, limestone unit, about 35 feet above base. 

20. Septacamera cf. S. kutorgae (Tschernyschev). 

Fragment of dorsal valve. Side view, X 1, USGS Joe. 21760-PC, limestone unit, 23 feet above base. 

21, 22, 25. Arctitreta cf. A. kempei (Andersson). 

21, 22. Silicified juvenile ventral valve. Exterior view, X 1, interior view, X 2, USGS Joe. 23083-

PC, lower part of limestone unit. 

25. Large calcareous ventral valve having attached ventral valve of Kuvelousia sphiva, X 1, 

USGS Joe. 23062-PC, limestone unit, 13-15 feet below top. 

23, 24. Waagenoconcha cf. W . irginaefonnis (Stepanov) . 

23. Flat calcareous ventral valve, X 1, USGS loc. 23061-PC, limestone unit, 150 feet below 

top. 

24. Natural impression of dorsal exterior, X 1, USGS Joe. 23061-PC, limestone unit, 150 feet 

below top. 

26-28, 34, 35. Spiriferella draschei (Toula) . 

26, 28. Large calcareous shell. Dorsal and anterior views, X 1, USGS Joe. 23083-PC, lower part of 

limestone unit. 

27. Large calcareous shell. Side view, X 1, USGS Joe. 23083-PC, lower part of limestone unit. 

34. Silicified ventral valve. Posterior view, X 1, USGS Joe. 21748-PC, limestone unit. 

35. Silicified ventral valve. Ventral view, X 1, USGS Joe. 21748- PC, limestone unit, 240 feet 

below top. 

29-33. Stenoscisma spitzbergiana ( Stepanov). 

Steinkern having shell mostly exfoliated. Dorsal, posterior, ventral, anterior, and side views, X 1, 

USGS Joe. 23048-PC, sandstone unit, 45 feet above base. 
FOSSILS FROM THE TAHKANDIT LIMESTONE