The Kinnikinic Quartzite 

of Central IdahoRedefinition and Subdivision 

By S. W. HOBBS, W. H. HAYS, and R. ]. ROSS, ]R. 

CONTRIBUTIONS TO STRATIGRAPHY 

GEOLOGICAL SURVEY BULLETIN - 1254-J 

Restriction of Kinnikinic Quartzite to a 

distinctive unit of Middle Ordovician age 

and description of this and five older 

stratigraphic units included in the 

Kinnikinic as originally defined 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

William T. Pecora, Director 

U.S. GOVERNMENT PRINTING OFFICE 

WASHINGTON: 1968 

For sale by the Superintendent of Documents, U.S. Government Printin~[Oftice 

Washington, D.C. 20402 • Price 15 cents (paper cover) 
CONTENTS 

Page 

Abstract---------------------------------------------------------- J1 

Introduction______________________________________________________ 1 

KinnikinicQuartzite as used by Ross________________________________ 3 

Necessity of stratigraphic revision____________________________________ 8 

Stratigraphic sequence near Clayton, Idaho____________________________ 9 

Kinnikinic Quartzite redefined___________________________________ 9 

Ella Dolomite___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 12 

Clayton Mine Quartzite_____________________________________ ___ 15 

Stratigraphic sequence on upper Squaw Creek_________________________ 17 

Cash Creek Quartzite__________________________________________ 18 

Carbonate-siltstone sequence below the Cash Creek Quartzite________ 19 

Lower quartzite_______________________________________________ 21 

Conclusion_____ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 21 

References cited _______________________________________ -----_______ 22 

ILLUSTRATIONS 

Page 

FIGURE 1. Index map of central Idaho showing location of area illustrated 

in figure 2_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ J3 

2. Geologic map of part of the Bayhorse region, Idaho, showing 

location of measured stratigraphic sections________________ 4 

3. Columnar sections of two predominantly quartzitic sequences 

in the Bayhorse region, Idaho____________________________ 6 

III 

CONTRIBUTIONS TO STRATIGRAPHY 

THE KINNIKINIC QUARTZITE OF CENTRAL IDAHOREDEFINITION AND SUBDIVISION 

By S. W. HoBBs, W. H. HAYs, and R. J. Ross, JR. 

ABSTRACT 

Detailed study of the Kinnikinic Quartzite as defined by C. P. Ross in the 

Bayhorse region, Idaho, has resulted in subdivision of Ross' formation into six 

formations. Two similar but demonstrably distinctive sequences of quartzitecarbonate-quartzite units have been measured and described. The name Kinnikinic is retained for the uppermost pure well-sorted quartzite of one of the 

sequences. The Kinnikinic, as thus restricted, is the Kinnikinic of most other 

workers in central Idaho. It is about 700 feet thick, is overlain by the Saturday 

Mountain Formation, and is definitely dated as Middle Ordovician. The massive, commonly sandy, dolomite that unde·rlies the redefined Kinnikinic is 700 

feet thick and contains an early Middle Ordovician fauna. This unit is named 

the Ella Dolomite. More than 2,000 feet of poorly sorted impure feldspathic 

quartzite and some fissile shale and siltstone lies conformably below the ElHt 

Dolomite and is named the Clayton Mine Quartzite. The age of this lower 

quartzi.te .is unknown, but the unit appears to be older than Middle Ordovician. 

The other quartzite-carbonate-quartzite sequence ·is overlain ,by shales containing unequivocally Middle Cambrian fo·ssils and is thus Middle Cambrian or 

older. The upper quartzite of this sequence, named the Cash · Creek Quartzite, is 

about 1,200 feet thick and has distinctive lithology. Nearly 600 feet of dolomite, 

thin-bedded color-banded shaly limestone, and some thin flagstone beds underlie 

the Cash Creek Quartzite. A thick-bedded fairly pure quartzite forms the basal 

unit of this sequence. Only about 400 feet of .the basal unit is exposed ab<?ve a 

thrust fault that ,bottoms the sequence. 

INTRODUCTION 

The l{innikinic Quartzite was named by C. P. Ross (1934) fron1 

extensive exposures o:f quartzitic rocks along the lower reaches o-:f 

l{innikinic Creek in the Bayhorse region, Custer. County, Idaho. He 

considered the :formation to be o:f Ordoviqian age and limited definite 

application o:f tlie name to strata extending :from the vicinity o£ Kinnikinic Creek northeastward 20.1niles ·to the vicinity o:f Round Valley, 

near Challis. In subsequent work, Ross (1947, 1961, 1962) extended 

Jl 
J2 CONTRIBUTIONS TO STRATIGRAPHY 

the name to other areas, and other workers including Anderson and 

Wagner (1944), Sloss and Mori·tz (1951), Scholten (1957), Shockey 

( 1957), Anderson ( 1961), and Mapel, Reed, and Smith ( 1965) applied 

the name to quartzites elsewhere in Idaho that correspond generally in 

both lithology and age to those described by Ross at the type locality. 

Our detailed work in the Bayhorse region from 1963 to 1966 showed 

that the quartzites mapped by Ross as a single unit and named the Kinnikinic by him are several map units of different composition and age. 

Only one of these units fulfills the basic criteria upon which the Kinnikinic was established as a formational unit. The basic changes that 

these new concepts make in the description of the ·type Kinnikinic 

Quartzite are to reduce its thickness from more than 3,500 feet to less 

than 1,000 feet and to eliminate the calcareous units that were previously mapped as lenses in the quartzite. Such revisions of central 

Idaho stratigraphy as are ·proposed here were realistically anticipated 

by Ross (1934) when he first described in detail the lower Paleozoic 

formations in •the Bayhorse region. He stated (p. 940): 

In considering the Paleozoic •stratigraphy of south-central Idaho it should 

be borne in mind that the structure of the region is complex. In general, the 

rocks are steeply tilted ; in many places they are contorted and locally overturned. Normal faults are plentiful, and many have dipslacements of several 

thousand feet. In •Some places, notably in the Wood River region, there are 

closely spaced reverse faults. Paleozoic strata are eXJtensively intruded by 

igneous rocks of at least two ages. Metamorphism resulting f.rom these intrusions 

bas Jocally changed ·the rock's a:1most beyond recognition. La.rge areas are covered 

by Tertiary lava, making it impossible to trace directly the connection between 

different masses of :the older rocks. 

Regarding the Oam:brian( ~) System, he stated (p. 940-941): 

No Cambrian fossils a·re known, and some of the beds now supposed to belong 

to other systems may conceivably ,be Cambrian, so that some revision i:s to be 

expected -in the future. 

Figure 1 is an index may showing the locaJtion of the mapped area, 

and figure 2 is a generalized geologic map of a part of the Bayhorse 

region, based on the work .by Ross (1937), that emphasizes the distribution of the quartzites and the intercalated carbonates, identifies the 

bounding formations where these are known, and outlines the blanket 

of Challis Volcanics that greatly hinders correlation between outcrops 

of older rock. The positions of the measured sections and of the 

sections ·that are described in more general .terms are also shown in 

figure 2. The stratigraphic and structural compHcations of the area, 

some of which are the subject of this paper, are extensive and when 

worked out will lead to a reinterpretation of the structure and a refinement of the areal geology. Figure 3 i1lustrates the stratigraphic sue-
THE KINNIKINIC QUARTZITE OF CENTRAL IDAHO J3 

0 25 50 75 

A 

100 MILES 

rea ofth;s . 

figure · . 

FIGURE 1.-Index map of central Idaho showing location of area illustrated in 

:figure 2 (strippled). Numbered rectangles show location of the following 

7 ~-minute quadrangles: 1, Bay horse Lake; 2, Bayhorse; 3, Bradbury Flat; 

4, Clayton ; 5, Bald Mountain ; 6, Potaman Peak. 

cession a;t three places in the Clayton quadrangle where the quartzites 

and some of the associated formations are well exposed and apparently 

structurally undisturbed. 

KINNIKINIC QUARTZITE AS USED BY ROSS 

All the quartzites shown in figures 2 and 3 and the dolomitic and 

argillaceous rocks intercalated in the quartzites were included in the 

Kinnikinic as defined by Ross (1934). Ross described the Kinnikinic 

in more detail in his bulletin on the Bay horse region ( 1937), and 

salient parts of this description (p. 17-18) are quoted here: 

Okaracter.-Most of the Kinnikinic quartzite is well bedded and nearly 

pure, but shaly partings and subordinate amounts of somewhat shaly beds 
CONTRI~UTIONS TO STRATIGRAPHY-.-

Q . 1 2 3 4 MJLES . 

FIGURE 2.-Part of the Bayhorse region, Idaho, showing geology and location of 

measured stratigraphic sections. Base and geology generalized and slightly 

modified after .C. P. Ross (1937, pl.l). 
THE KINNiiaNIC QUARTZITE OF CENTRAL IDAHO J5, 

EXPLANATION 

f~};f~#lii~~~~ Quat~rn~ry talus glaciers and · · · · · · iandslides 

Tertiary · Challis Volcanics 

Cretaceous or Jurassic gabbro and 

granodiorite 

Mississippian Milligen Formation 

Middle Ordovician and younger 

Saturday Mountain Formation 

Middle Ordovician and older rocks* 

Includes Kinnikinic Quartzite, Ella Dolomite, Clayton MiM 

Quartzite, Cask Creek Quartzite, and unnamedformatiom .. May include rocks as old' as Precambrian 

Ordovician(?) Ramshom Slate 

Cambrian(?) Bayhorse Dolomite and· Garden Creek Phyllite 

294-509-68--2 

Contact 

Fault 

Dashed where approximately located 

20 

__j_ 

General strike and dip of beds 

~ 

Mine ~ Inactive mine 

Line of measured ~ section 

*Kinnikinic Quart~ite as Used by Ross (1934). 
CONTIUBUTIQNS TO STRATIGRAPHY 

EXPLANATION 

A 

[·:: ... ~ :_.' . . : ::. ·: ··~ ·. ::1 

Quartzite 

· ·

0 

• ·• • 0 • c , . 6 • '1 . 0 . . . . 0 .• oe • . c;t · 0 . . . . 

Pebbly quartzite 

[·'. · ... : ..... ·. '.1 : ·-·. ·.·I . .... " · • • 0 • • • 

Feldspathic quartzite 

I:·· ... F..£4· ---.,.---"T·--::-r--

Dolomitic quartzite 

C:+-··.:·. ·:·:23' 

Shaly or silty quartzite 

(: ( /:: :~/ ;: f:); (.~ \ :.:J 

Crossbe_dded quartzite 

§"' ...... ~ 

~-=--~-=-~ Siltstone orsiltite 

§"' 0::~ ... - ... _,_ ... =;::r..~. ... g "'-···--r-··· 

&I(Zc;~~~~iiWo;;-e 

§;;-----;§ 

E;~---=:--7-;:§1 ' 

Sand:( shal~ 

I: : : : : : :I - Limestone 

Silty limestone 

I:.: : : : : :I 

Shaly limestone 

Dolomite 

Silty dolomite 

lt%i45811 

Sandy dolomite 

Cherty dolomite 

FEEt 

0 

500 

1000 

FIGURE 3.-Columnar sections of two predominantly quartzitic sequences in the 

Bayhorse region, Idaho. Column A constructed from sections on the north 

Side of the Salmon River, 1-2 miles west of Clayton, Idaho. Kinnikinic Qual"tzite part of the section computed along line A.-1, and Ella Dolomite and Clayton 

Mine Quartzite parts .of section measured along line A-2. Columns B and 0 
Q) 

·;:;:; 

-'t 

ro 

:::s 

Ql 

~ 

Q) 

Q) 

lo... 

() 

..c: 

(/) 

ro 

() 

THE KINNIK.INIC QUARTZITE OF CENTRAL IDAHO J7 

B 

.. ··.:· .. · .. =.··. ·:· 

:·.: .:...: :.-:-~ ·::- :: :~ :<: I . .-:~--::._ ~:,:.-. .- :·->--· :· I ·. ·.;. .. · :.· .. ~- .... ·. ·. : · .... . ... .. = .. . · -:. · I .'·: ~:· .:: ..: :.:~: 

-: ?~ -_:·_:~-~ :_.~~ ~ ~~ ·: --_I 

Base covered by 

Challis Volcanics 

II 

I 

·c: 

-:::s 

~ ro 

c: 

0 

.0 

lo... 

ro 

() 

c 

·· ···-:-::···-... 

. ::__:::_ .. , __ .. , __ ... 1--"·.-·:·-: .. -

. . . . 

---- -~: .... ~::.:::.::.::.:,;·. 

FAULT(?) . 

Ill 

Ill 

Q) 

c: 

..ll:: 

u 

:c 

T 

FAULT(?) 

are sections on the west side of Squaw Creek between 5 and 7 miles above 

its junction with the Salmon River. Cash Creek Quartzite measured along line 

B, and the carbonate unit, along line 0. Thickness of lower quartzite computed from exposures in valley of Boundary Creek. Vertical scale of column A. 

is one-half that of columns B and 0. 
. CONTRIBUTIONS TO . STRATIGRAPHY 

:are common. The prevalent color of the fresh quartzite is nearly white, but 

:in most exposures some or all of the beds have a distinctive lavender cast, 

;which i~ useful in recognizing isolated outcrops -of the formation. Many 

exposures are stained 1brick red, largely through the oxidation . of flakes of 

specularite of hydrothermal origin, which are commonly disseminated sparsely 

through the quartzite and quartz veinlets. The rock is coin;posed· essentially of 

a mosaic of detrital quartz grains 0.1 to 0.5 millimeter in diameter and slightly 

enlarged by deposition of secondary silica. These grains are set ·in a siliceous 

cement containing sericite. : 

The more argillaceous beds are generally also calcareous. They are on the 

average finer-grained than the quartzite and contain dolomite, sericite, graphite, 

chlorite, and epidote in varying proportions. In several places, mainly in 

the vicinity of Clayton, the formation contains irregularly lenticular aggregates 

of impure magnesian limestone and argillaceous beds that are large enough 

to be mapped separately * * *· Conglomerate was noted in the Kinnikinic 

quartzite only in the vicinity of Little Bayhorse Lake, near the head of 

Bayhorse Creek. 

The Kinnikinic quartzite is everywhere contorted. In many exposures the 

effects of crenulil,tiori ·are surprisingly intricate for a rock of this character. 

On the slope flanking the Salmon River. on the east below the mouth of Bay horse 

Creek contorted beds. with an averag~ dip of fully 20° are exposed through 

a v_ertical range of 2,400 feet. The river cuts almost directly across an anticline 

in this formation west of Clayton. The west side of the fold is almost vertical 

near the river and has a width of 4,000 feet at the base of the exposure in the 

canyon. These data indicate that the Kinnlkinic qua,rtzite is a,bout 3,500 feet 

thick or possibly somewhat more, a thickness that accords well with those indicated by the structure sections representing other parts of the region * * *· 

Age.-Bedding surfaces in the quartzite show fucoid markings in many places. 

Such markings are especially plentiful in the hills east of Round Valley. The 

limestone intercalated in the formation near the' mouth of Kinnikinic Creek 

contains small calcareous algae. These organic remains, the only fossils known 

in the formations, are not accurately identifiable. As the formation lies below 

the Saturday Mountain formation (Upper Ordovician) and above the Ramshorn 

slate (lowest Ordovician) with approximate concordance in attitude, it is 

doubtless of Lower or Middle Ordovician age. 

NECESSITY OF STRATIGRAPHIC REVISION 

In several places in the Bayhorse region, the areal distribution 

o£ quartzite units and the juxtaposition of quartzitic sequences of 

different characteristics and age are the results of a complex history 

that is as yet little understood. New fossil localities, the stratigraphic 

sequence iri loeal sections unbroken by faults, the recognition of several 

distinctive varieties of quartzite, and new mapping indicate clearly, 

hbwever, that the Kinnikinic Quartzite of Ross consists of several 

thick mappable units of different ages and that the name Kinnikinic 

Quartzite should be redefined and restricted. 

The complexity of the stratigraphy ·is . shown by the columnar 

sections· in figure 3, Which represent units ~ncludedjn Ross' Kinnikinic. 

Examination of fossils reveals that the rocks shown in ·columns B 
THE KINNIKINlC QUARTZITE OF CENTRAL IDAHO J9 

and 0 of figure 3 are of Cambrian or older age and, hence, older 

than the upper quartzite of column A. (the authors' restricted Kinnikinic) and the dolomite unit below it, both of which are of 

Ordovician age. The lower quartzite of column A., the lithologically 

different upper quartzite of column 0, and the carbonate-siltstone 

unit of column 0 are almost certainly separate units. The lower 

quartzite of column 0, whose basal stratigraphic relations are not 

yet known, is probably another distinct unit. In all, two carbonatebearing units and four quartzite units are discussed in the present 

report, starting with the restricted Kinnikinic and working generally 

downward in the section to units less well dated and less fully understoQd. Three new formation names are proposed. So little is yet known 

about the age and regional characteristics of most of · the units that 

correlations are avoided for all but the Kinnikinic as restricted. 

STRATIGRAPHIC SEQUENCE NEA;R CLA~TON, IDAHO 

KINNIKINIC QUARTZITE REDEFINED 

As a consequence of the subdivision of_ the original Kinnikinic 

Quartzite of Ross, it is proposed here that the name IGnnikinic be restricted _to the uppermost quartzite unit exposed in the Clayton quadrangle, Idaho-the upper unit of column A., figure 3. The original type 

locality of the Kinnikinic Quartzite was in the lower reaphes of Kinnikinic Creek near Clayton, Idaho, and the name was derived from 

that of the creek. However, the quartzites that crop out so prominently 

along the course of Kinnikinic Creek are now excluded from the Kinnikinic as redefined, and therefore the ~arne is not strictly applicable. 

Nevertheless, because of long usage that is generally consistent with the 

restricted definition of the Kinnikinic and the fact that rocks of this 

unit do _,occur within. 2 miles of IGnnikinic Creek, the name is retained. 

Die. tributi~~ 

The Kinnikinic as redefined is best exposed and most accessible 

on the west limb of a large anticline that is cut across -by the Salmoi1 

River along the south , edge of sees. 22, 23, and 24, T. 11 N., R. 17 

E ., Clayton quadrangle, Idaho. The top of the Kinnikinic is at ,the 

level of the river near the east end of the bridge that carries· U.S. 

Highway 93 ·across the Salmon River about 2 miles west of the town 

of Clayton, and the formation is exposed in roadcuts for about 800 

feet eastward from the bridge. This exposure along Highway 93 is 

designated the reference section .. Altho~gh this is one of. the least 

disturbed exposures of the quartzite known in the Bayhorse region, 

faulting has caused some duplication of the formation, and the computed thickness of approximately 700 feet in this area is probably too 
JlO . CONTRIBUTIONS. TO STRATIGRAPHY 

great. Other exposures· of the Kinnikinic occur north of the reference 

section and east of the valley of Squaw Creek, but these are structurally 

isolated ·remnants of partial exposures surrounded by Challis Volcanics and a mantle of rock debris. To the northeast in the Bradbury 

Flat quadrangle (fig. 1, No. 3), Kinnikinic Quartzite is exposed ·along 

U.S. Highway 93 in the first outcrops south of the mouth of Mud 

Springs Gulch. Rather extensive exposures also occur in the eastern 

part of the Germer Basin in the southwestern part of the same 

quadrangle. 

The original description of the Kinnikinic by C. P. Ross emphasizes 

many characteristics that apply closely to the proposed restricted formation, and Ross' description has been used by him and others, but 

not by us, for correlation beyond the Bayhorse area. As a fortunate 

.result, where the name Kinnikinic has been used in other areas of central and southeastern Idaho, it has been applied in most places to 

quartzites whose lithology and age are similar to those of theunit as 

here restricted. 

Cha.raeter 

The Kinnikinic Quartzite as redefined is generally medium to thick 

bedded and exceptionally pure. The major part of the formation is 

composed of medium-grained well-sorted vitreous quartz grains cemented into a mosaic by secondary overgrowths of silica. Most grains 

are 0.1-0.5 mm in diameter, but a few scattered grains are larger. In 

many specimens, despite the tight cementation, the rounded shape of 

the original grains is visible with the hand lens. On fresh surfaces 

·the rock has a subvitreous to vitreous luster and usually shows a conchoidal fracture. Most of the rock is light gray to white, but locally 

some is darker gray and includes. a . few very dark layers. The reference section, west of Clayton, contains a disproportionate amount of 

·dark quartzite. Generally, the weathered surface is similar to the fresh 

surface in color, andonly locally where fracturing or brecciation has 

allowed the introduction of some hyd.rothermal iron-bearing minerals 

or has allowed the alteration of very small amounts of included hematite are weathered surfaces· stained brown, tan, or red. 

In general, .argillaceous material is limited to a few shale and shaly 

sandstone partings separating pure quartzite beds. Locally the upper 

part of the formation includes beds of dark-gray shale and mudstone, 

generally thin b.ut exceptionally several feet thick. 

Age 

C. P. Ross ( 1934, 1937) believed that the Kinnikinic Quartzite is 

essentially conformable with the overlying Saturday Mountain Formation. This interpretation is probably correct, but evidence of shear-
THE KINNIKINIC QUARTZITE OF CENTRAL IDAHO Jll 

ing in the poorly exposed basal dark shale of the Saturday Mountain 

Formation west of Clayton and erratic lateral variation in the apparent thickness of the shale from zero to a few hundred feet suggest 

that faulting of at least local extent is common near and subparallel 

to the base of the formation. The Saturday Mountain Formation was 

_dated as Late Ordovician at the time it was defined and described by 

C. P. Ross (1934). Subsequent studies by Churkin (1963) and R. J. 

Ross, Jr., and W. B. N. Berry (1963) established that at least part of 

the Saturday Mountain Formation is upper Middle Ordovician. The 

dolomite that underlies the redefined Kinnikinic in apparent conformity was mapped by C. P. Ross as a lens within the Kinnikinic, 

but' the lenslike distribution can now be demonstrated to result, at 

least in part, from faulting. Fossils from near the base of this dolomite 

in the Clayton section were determined by R. J. Ross, Jr., and John 

Huddle of the U.S. Geological Survey to be probably early Middle 

Ordovician. The Kinnikinic as redefined thus falls between the lower 

part of the Middle Ordovician and upper part of the Middle Ordovician. Fossil collections from the basal part of the overlying Saturday 

Mountain Formation were described by R. J. Ross, Jr., as follows: 

USGS Conn. D1410 CO. Saturday Mountain Formation, basal black shales. 

AHitude 5,600 ft. NWlANE:tA,NElA, sec. 27, T. 11 N., R. 17 E. Idaho coord., 

central zone: E. 385,650 ft., N. 945,450 ft. Clayton 7%-minute quadrangle, 

Idaho. 

Lordorthis variabilis Ross 

Rafinesquina? sp. 

Strophomena sp. 

1 soteZus rSp. 

Dolichoharpes? sp. 

Remopleu'rides sp. 

Amphilichas? sp. 

This assemblage is equivalent to fossils in the basal beds of the so-called 

Saturday Mountain Formation in the Lemhi Range. Its age is probably late 

Middle Ordovician. 

USGS Colin. D1464 CO. Saturday Mountain Formation, lower few hundred 

feet, south of Salmon River, SW%,NElANE1,4 sec. 27, T. 11 N., R. 17 E. Idaho 

coord., central zone: E. 385,700 ft. N. 944,840 ft. Clayton 7%-minute quadrangle, 

Idaho. 

Orthograptus quadrimucronatus v<ar. whitfieldi Hall 

Olimacograptus raricaudatus Ross and Berry 

Numerous indeterminate, badly sheared specimens of graptolites 

Age of this collection is probably equal to that of ithe zone of Orthograptus 

truncatus var. etheridgei, or Middle Caradoc; correlative with Trenton or late 

Middle Ordovician. 

USGS Colin. D1463 CO and Dl465 CO. Saturday Mountain Formation, just 

above top of Kinnikinic Quartzite, ut south end of anticlinal nose in SW14 sec. 
Jl2 CONTRIBUTIONS TO STRATIGRAPHY 

15, T. 11 N.; R. 17 E. Idaho coord.; central zone : E. 382,600 ft. N. 951,850 ft. 

Clayton 7%-minute quadrangle, Idaho. 

D1463 CO: 

Orthograptus? 2 spp . 

.. Leptograptus sp. 

DiceZZograptus or Dicranograptus sp. 

D1465 CO: 

alimacograptus sp. (a variety with a pair of tiny basal spines, and 

' rha:bdosome a little too narrow for a. bicornis s.s: )_ 

; Olimacagraptus cf. a. -bicoffl.is (no proximal endso preserved) 

.Ort1wgraptus Cf. 0. · calcaratus var ... acutus Elles and Wood 

·,. . . Qrthograp~us ·sp: 

, . Ample:cograptus? ·Sp . 

. .Afie o! th~se two collections is probably the same as that-of zone of O: ·bicornitt 

and ~one ' of· 0. truncatus etheridgei-Middle Caradoc, 'Tr(mtoll, ~r late .Middle 

Ordovicfan. Preservation of graptolites is poor: :rilore conservative · paleontologists would probably be reluctant to. carry -identifications <below the rank of 

genus to s:Pecies and variety. Despite this fact the dating is ·considered reasQp.able. 

· These · coilections from the lowest part of-the Saturday Mountain 

Formation are of late Middle -Ordovician -age, indicating not only that 

the Saturday Mountain is partly Middle Ordovician in age, but also 

that the Kinnikini~ can be no younger than lat~ Middle· Ordovician. 

ELLA .. DOLOMITE 

At least 700 feet of massive ;dolomite ·and-sandy dolomite lies below 

the Kinnikinic Quartzite in the anticlinal structure along the Salmon 

River canyon west of the town of Clayton. The dolomite beds ~II: . this 

fold bend down sharply into the nearly vertical east limb of the anticline and form spectacular exposures along the west side of Kirtnikinic 

Creek between ·a point near its mouth at Clayton and .t;he Clayton 

silver mine about Ilj2 miles upstream. These steeply dJpping_beds are 

the host rocks for the or~ , deposits of the. old Ella inirie near Clayton, 

and it. is proposed here .. that the mime ·Ella Dolomite, first used by 

Patton ( 1948), be used for this unit. 

Distribution 

Although this dolomite is exp~sed. along U.S~ Highway ·93 beneath 

the reference section of Kinnikinic and along Kinnikinic Creek n~ar 

the EUa mine, the best ·and least disturbed, section is· that ofth·e nearly 

flat-lying beds on the crest of the anticline, high on the cliffs that :form 

the north wall of theeanyon between the reference section of Kinnikinic Quartzite and the town of Clayton. This section, designated the 

type section and shown in column A of figure 3, i~ accessible l?y a 

jeep trail that connects the Squaw Creek road to the South Butte mine 

and extend's ·southeastward to the dolomite outcrops on the cliff face. 

The dolomite is also exposed on the south wall of the Salmon River 

canyon in the west limb of the anticline, and it extends as a discon-
THE KINNIKINIC QUARTZITE OF CENTRAL IDAHO J13 

tinuous band of outcrops southward for several miles on the east side 

of the valley of Sullivan Creek to a point where it is lost under a cover 

of Challis Volcanics. 

Small detached outcrops of dolomitic rocks that are thought to be 

correlative with the Ella Dolomite occur for several miles to the 

north-northwest of the type section in a gently rolling area in sees. 10 

and 15, T. 11 N., R. 17 E. This area is mantled in large part by 

Challis Volcanics, extensive talus, rock glaciers, and landslides through 

which only isolated and largely indeterminate pa,tches of the preChallis bedrock project. A thin fault slice of Ella Dolomite is exposed 

at ·an altitude of 9,000 feet on the ridge crest near the center of sec. 11. 

Dolomite ·at the same stratigraphic position in a quartzite sequence as 

the type Ella Dolomite crops out at intervals for several miles along 

a north-trending line east of the Salmon River ·and the East Fork 

in the southeast corner of the area shown in figure 2. Although no 

fossils have been identified from this dolomite, it is correlated with the 

type Ella. 

Charaeter 

The Ella Dolomite is a sequence of predominantly medium- to thickbedded dolomite, most of which contains some silt and fine sand, 

usually in thin laminae that on weathered surfaces show. as fine ribbing 

or a hackly texture. This lamination is not obvious o_n fresh fractures. 

The dolomite is predominantly fine grained, but some portions as much 

as 25 feet thick are medium to coarsely crystalline. The color generally 

is medium to medium-dark gray, commonly with a brown or tan cast, 

but some layers are lighter gray, and some are da~k gray to almost 

black. Weathered surfaces are predominantly tan, brown, or yellowish 

gray. Some layers near the base have a coarsely crystalline texture and 

dark-gray color and weather to deep brown. This basal zone is 

distinctive and has proved useful as a marker bed. 

Locally, ·as. at the horizon of the small prospect at the end o£ the jeep 

trail northwest of Clayton and about 230 feet above the base of the 

·Ella, a 20- to ·30-foot zone of beds is more siliceous. Some layers in this 

zone consist· of fine-grained quartzite, some of sandy dolomite, and 

some of chert that appears to have replaced other mate.rial. One highly 

silicified zone has an oolitic appearance that seems to have resulted 

from the replacement of subspherical algal structures by silica. 

Microlayered siliceous laminae are also believed to result from the 

re:£?lacement of algal structures. 

Age 

Brachiopods and conodonts from a zone near the base of the Ella 

Dolomite and conodonts £rom the dolomite about 450 feet above the 

base were determined by R. J. Ross, Jr., and J. W. Huddle of the U.S. 
J14 CONTRIBUTIONS TO STRATIGRAPHY 

Geological Survey to be probably of early Middle Ordovician age, 

and the Ella Dolomite is thus assigned to the Middle Ordovician. The 

narrow sliver of Ella that crops out northwest of the Clayton silver 

mine onthe high ridge in sec. 11, T. 11 N., R. 17 E., is much like the 

lower part of the measured section and contains poorly preserved 

fossil fragments that are similar to those described for the type 

seotion. 

The following lists of the fossils from the vicinity of the type section 

were given by R. J. Ross, Jr., and J. W. Huddle (written commun., 

1966): 

USGS Colin. D1594 CO. Ella Dolomite, from lower 30 ft near base. Altitude 

7,000 ft. NW cor. NE:tA,SE:tA, sec. 23, T. 11 N., R. 17 E. Idaho coord., central 

zone: E. 390,660 ft., N. 948,400 ft., Clayton Tlh-minute quadrangle, Idaho, 

Brachiopods: (Anomalorthis zone, Whiterock Stage) 

Anomalorthis sp. 

Orthambonites? sp. 

Desmorthis? sp. 

Conodonts: 

Acodus auritus Harris and Harris 

Acodus sp. 

Drepanod1JS sp~ 

Eorieoplrioniodus eryptodens Mound 

Falodus brevis (Harris) 

Leptochirognathus gracilis? Branson and Mehl 

Leptochirognathus prima Branson and Mehl 

M ultioistodus tridens (Cullison) 

Multioistodus 2 spp. 

N eoff!-Ultioistodus COtr£press'l!s H~rris and Harris 

Oistodus cf~ 0• contractus,Lindstr.om 

Paltodus sp. 

Panderodus sp. 

Pteracontiodus aquilatus Harris and Harris 

Scandodus? sp. 

Tricladiodus clypeus Mound 

Huddle stated: "Probably this collection is early Middle Ordovici~n in age 

(Whiterock to Marmor). Multioistodus and Leptochirognathus are, r~rely 

found, and Eoneoprioniodus, N eomultioistodus, and Pteracontiodus were described recently. Their ranges are not firmly established, but in the Arbuckle . 

Mountain area they were described from the West Springs Formation in the 

top or the Arbuckle Group, the Joins and McLish Limestones of the Simpson 

Group, and the Dutchman Limestone of Missouri. Several ofthese genera occur 

together and may have belonged in the same animal. They are not always 

present in early Middle Ordovician formations but seem to be a good index of 

that age when they are found. Multioistodus occurs near the middle of the 

Antelope Valley Limestone Member of the Pogonip Formation in the Groom 

Range in Nevada." 
THE KINNIKINIC QUARTZITE OF CENTRAL IDAHO J15 

USGS Colln. D1848 CO. Ella Dolomite, approximately 450 ft above base. Altitude 7,280 ft. On southwest side of ridge crest. NElA, sec. 23, T. 11 N., R. 17 E. 

Idaho coord., central zone: E. 391,000 ft, N. 949,200 ft. Clayton 7%-minute 

quadrangle, Idaho. 

Oyrtonioaus jle{JJuosus (Branson and Mehl) type element 

prinoniodina element (probably belongs here, cordylodus element with 

compressed base 

Oyrtonioaus? n. sp. or Phragmodus? 

ligonodina element probably belongs to this species, Dichognathus typica 

element may belong to this species 

Keislognathus n. sp. 

4 nondenticulated bar elements 

Erismodus? horridU8 Harris 

Eri8modus? sp. 

Hibbardella sp. 

Drepanodus sp. 

Paltodus sp. 

Prioniodina sp. 

Huddle (written commun., 1967) stated: "This is an undescribed fauna, and 

its age is uncertain. Erismoaus? horridus was described from the Joins Formation of Oklahoma, and this suggests an early Middle Ordovician age for the 

collection. 

The first three species listed are probably biologic species, but this can only 

be determined by additional collections. The other species listed are probably 

Form species." 

CLAYTON MINE QUARTZITE 

In the eore of the anticline west of Clayton, the Ella Dolomite rests 

in apparent conformity on a series of quartzitic rocks that ·are significantly different from the Kinnikinic Quartzite that overlies the 

Ella. In contrast to the Kinnikinic, these quartzites are . heterogeneous 

in composition, degree of sorting, and bedding characteristics, and are 

at least 2,000 feet .thick. The base is not exposed. The name Clayton 

Mine Quartzite is applied here to these rocks from exposures in the 

high cliffs and high ridge west of the Clayton mine on Kinnikinic 

Creek. The name Clayton Quartzite was given to this unit by Patton 

(1948), but as the name Clayton alone is preempted, the change to 

Clayton Mine has been made. 

Distribution 

The rocks of this unit are perhaps the most widely distributed of 

the quartzites in the general Bay horse region. The massive cliffs below 

the Ella Dolomite on both sides of the Salmon River canyon west of 

Clayton are all of this unit, and these same resistant rocks can be 

traced for several miles north of the river, where they make up the 

high ridges between Squaw Creek and Kinnikinic Creek. They also 

extend south into the Potaman Peak quadrangle, where they form 

many of the highest ridges. Other extensive exposures of quartzite are 

(1) along the Salmon River downstream from Clayton from near the 

junction with the East Fork of the Salmon River to 5 miles south 
J16 CONTRIBUTIONS TO STRATIGRAPHY 

of Challis, (2) for several miles up the East Fork, (3) on Poverty 

· Flat, and ( 4) north of the Bay horse Lakes. · 

Character 

The description of the Clayton Mine Quartzite that follows is based 

on the section measured in the Salmon River canyon west of Clayton, 

which is designated the type section and is illustrated in column A. 

of figure 3. The general features of the quartzite here appear to be 

characteristic of the formation over wide areas, although variations 

probably occur from place to place because of local facies changes that. 

generally exist in rocks of this kind. 

Bedding ranges widely from thick bedded or massive to thin bedded. 

Thin zones of flagstone occur locally. Cross-lamination occurs at intervals throughout the measured section but seems to be more com-

. mon in the lower half. Some beds as much as 10 feet thick form but 

one set of through-going cross laminae; more commonly the crosslaminated layers are much thinner. 

The section ·consists pr~dominantly of coarse- to medium-grained 

feldspathic quartzite, but very thin shale partings occur throughout, 

and the lower hal£ contains several zones of shale as much as 40 feet 

thick and one zone 200-300 feet thick of interlayered quartzite, shaly 

quartzite, and thin beds of shale and siltstone. The great bulk of the 

rock is composed of fairly well rounded quartz grains that are characteristically poorly sorted. Thin conglomerate lenses, pebbly quartzite, and scattered pebbles occur in the upper two-thirds of the section. The upper 250 feet is :predominantly pebbl~..,b~aring quartzite 

containi~ rounded quartz pebbles that are mainly about one-fourth 

inch in diameter but are locally larger than 1 inch. The pebbles are 

predominantly colorless to dark-gray vitreous quartz and quartzite, 

but a few are chert, feldspar, and siltite. Feldspar, usually more angular than the quartz, is distributed throughout the section, except £or 

the interval between 225 .and 475 feet from the top, which is virtually 

feldspar free. E·ven this interval contains microscopic structures that 

suggest complete replac~ment of original feldspar grains by quartz 

and sericite. The feldspar ranges in size from small specks to fragments 

nearly half an inch long and in places forms as much as 20 ( ~) percent 

of the rock. Some is fairly fresh, but most is altered and is dull yellowish gray to white. 

The quartzite ranges from medium light gray •to very light gray. 

Much has a yellow to orange east, and a little is pink or purplish gray. 

It generally appears less clean and vitreous than the Kinnikinic. 

weathered surfaces are commonly grayish orange, moderate brown, 

grayish red, and yellowish ·gray. 

. The thicker intervals of shale and siltstone are similar lithologically 

to the thi~ partings that separate many quartzite beds. They are well 
THE KINNIKINIC QUARTZITE OF CENTRAL IDAHO J17 

bedded, generally fissile, ·and variably micaceous, and they commonly 

include sandy layers. The shale is mainly pale yellowish green or greenish gray; a little is grayish green and dark purplish gray. The silt"" 

stone is grayish yellow and greenish gray. 

Two layers of dolomite separated by •about 3 feet . of shale are· enclosed in quartzite at 1,730 feet below the top of the section; the upper 

layer is 15 feet thick, and the lower is 2 feet thiek. The dolomite is 

fine grained, medium to dark gray, and slightly impure. It weathers 

to deep chocolate brown. Silty laminations weather out ·as ·fine ribbing 

on the surface. 

The Clayton Mine Quartzite on the north side of the Salmon River 

west of Clayton measures 1,980 feet from the base of the overlying 

Ella Dolomite to the lowest exposure at the top of talus that covers 

the lower slopes. The rocks of this type section are little deformed and 

represent a minimum thiclmess for the formation. An unknown thickness lies below the lowest outcrop. Along U.S. Highway 93 east of the 

type section, a few exposures of silty quartzites and shales on the east 

limb of the anticline are perhaps str31tigraphically lower than the 

base of that seotion. T-hese beds, however, are separated from the 

measured section by a shear zonB along which the displacement is 

unknown, ·and therefore they ca1mot be projected into that seotion. 

Age 

The age of the Clayton Mine Quartzite is not known with certainty, 

as no fossils have been found in any part of the sequence and its basal 

stratigraphic relations are unknown. The fact that the formation lies 

with apparent conformity below the basal fossil-bearing zone of the 

Middle Ordovician Ella Dolomite suggests an Early Ordovician age 

for at least the upper part of the quartzite. However, the contact may 

be a disconformity representing a hiatus of rrndefinite duration, and ·all 

the quartzite may be older than Ordovician. 

C. P. Ross (1937) described the Kinnikinic, as he defined it, as 

resting on Ramshorn Slate, which he considered to he of earliest 

Ordovician age from fossil evidence discovered 6 mil~ south of the 

area shown in figure 2 in rock he correlated with ·the Ramshorn. This 

correlation is now in doubt, and thus the Ramshorn is no longer useful 

in limiting the age of the Clayton Mine Quartzite, which is above it 

and is included in the original Kinnikinic Quar,tzite. 

STRATIGRAPHIC SEQUENCE ON UPPER SQUAW CREEK 

Squaw Creek, a major stream along the west edge of the Clayton 

7¥2-minute quadrangle, cut across a sequence of quartzites and carbonate rocks for about 2 miles between the mouth of Cash Creek and 

the Red Bird mine. This sequence, roughly analogous to the l{innikinic 
J18 CONTRIBUTIONS TO STR,ATIGRAPHY 

Quartzite, Ella Dolomite, and Clayton Mine Quartzite, was included 

by C. P. Ross in his original Kinnikinic unit. These rocks are now 

known to be separate and distinct and definitely older than the Kinnikinic, as here restricted, and the Ella. Columns B and 0 of figure 3 

illustrate the sequence. 

CASH CREEK QUARTZITE 

Distribution and thickness 

T<he upper quartzite of this sequence ihas been identified only in the 

massive cliffs :along the west side of Squaw Creek south of the n1outh 

of Cash Creek and is here named the Cash Creek Quartzite. Some of 

the quartziticbeds that are exposed several miles to the east in the upper 

reaches of Cash Creek and beyond also m·ay belong to this unit. A 

section 1,105 feet thick of the Cash Creek Quartzite, designated the 

type section, was measured in the steep cliffs about a quarter of a mile 

south of the mouth of Cash Creek and almost entirely on the west side 

of Squaw Creek. It is overlain by a unit of siliceous platy shale and 

siltstone at least 200 feet tfuick that contains a Middle Cambrian trilobite fauna. The type section is terminated at the base, a short distance 

east of Squa:w Creek, by ra cover of Challis Volcailics, but the covered 

interval is exposed witlhin a mile to the south .along the strike of the 

formation. Map projections indicate that not more than 200 feet of the 

basal part of the formation is concealed at the type section. The total 

thickness of this quartzite unit can thus be quite reasonably estimated 

at between 1,200 ·and 1,300 feet. 

Character 

The Cash Creek Quartzite along Squaw Creek is all quartzite, except 

for rare thin layers of shale and silty quartzite. Beds are predominantly medium to thick and some of them, particularly in tJhe lower 

half, are cross-l.aminated. Although some intervals are nearly white or 

various shades of pure gray, more colorful quartzite, in . sha:des of 

yellowish gDay, brownish gray, light orange, and subtle pink and 

purple, is characteristic of the ;formation. 

Grain size ranges from fine to coarse. Pehble layers ·and lenses and 

isolated pebb'les are scattered through the section 'but nowhere are 

sufficiently abundant for the rock to be called conglomerate. Sorting 

is good in some rbeds but is more commonly fair to poor. The upper 

two-thirds of the unit is nearly pure quartzite and pebbly quartzite; 

the lower i'hird oontains as much .as 5 percent altered feldspar. Some 

feldspar grains are as much as 3 mm in diameter, but most are much 

smaller. 
THE KINNIKINIC QUARTZITE OF CENTRAL IDAHO J19 

Age 

The Cash Creek Quartzite is overlain conformably by greenishgray, yellowish-gray, and reddigh siltstone and shale, much of which 

weathers oo deep brick red. Several hundred feet of these beds is exposed in the saddle above the top of the type section, but the total 

thickness is not known because the Challis Volcanics overlie the shale 

to · the west. These shales contain fossils th3!t are especially abundant 

within 1-2 feet of the top of the quartzite and that have been determined to be of unequivocally Middle Cambrian age by A. R. Palmer of 

the U.S. Geological Survey. Palmer describes the fauna as :follows: 

USGS Colin. 5461 CO and 5462 CO. Siltstone above Cash Creek Quartzite, on west 

side of top of hill 6897, west of Squaw Creek, 3.5 miles north of mouth of Bruno 

Creek. Idaho coord., central zone : E. 373,800 ft, N. 976,270 ft. Clayton 772-

minute quadrangle, Idaho. 

Nisusia sp. 

Pagetia sp. 

cf. Spencia sp. 

Ptychoparioid trilobites of early Middle Cambrian aspect 

Undetermined corynexochoid trilobites, cranidia only 

Acrothele? sp. 

Gogia sp. 

(written commun., 1965) Palmer stated: "The presence of :the distinctive 

eodiscid trilobite Pagetia is a definitive element in this collection. It is known 

in western N or.th America only from beds older than media·l Middle Cambrian. 

Nisusia is a distinctive ribbed brachiopod found only in Middle Cambrian 

,beds. Gogia ls a distinctive echinoderm which is represented by a number 

of nearly complete specimens in this collection which show weH the charac-

,teristic morphology of this Middle Cambrian genus. The ptychoparioid trilobites are not well enough preserved to be satisfactorily named, but their 

aspect is most characteristic of forms from the lower part of :the Middle 

Cambrian. The presence of a corynexochoid trilobite is the most significant 

evidence for a Middle Cambrian age from the trilobite data. Corynexochoid 

trilobites are confined, except for a few unusual and distinct exceptions, to 

Middle Cambrian and older beds, and forms such as those in this collection,. 

with long eyes, are medial Middle Cambrian or older." 

On the basis of these relations, the Cash Creek Quartzite is considered .to be probably of Early or Middle Cambrian age and possibly 

equivalent to the Flathead Quartzite. Further work may clarify the 

relation of these rocks to the rest of the section. 

CARBONATE-SILTSTONE SEQUENCE BELOW THE CASH CREEK 

QUARTZITE Distribution 

Between the Cash Creek Quartzite and a lower series of massive 

quartzites is a group of very distinctive strata that includes impure 

dolomite, impure limestone, fissile siltstone, and flaggy siltstone. These 

rocks are known only below the Cash Creek Quartzite on Squaw Creek 

and are most extensively exposed in the lower part of the cliffs that 
J20 CONTRIBUTIONS TO STRATIGRAPHY . ' 

border the west side of the creek. The unit crosses Squaw Creek valley 

and is exposed in the creek bed and in roadcuts along the east side of 

the creek about one-fourth mile north of the mouth of First and 

Second Creeks-a tributary flowing into Squaw Creek from the east. 

Character 

The base rests conformably on massive clean subvitreous unsorted 

quartzites. The lower 65 feet is composed of thin-bedded micaceous 

gray, greenish-gray, and purplish-gray slate or siltstone and sandy 

siltstone and local layers of micaceous quartzite. T>he upper 25 feet 

of the siltstone splits along the bedding into smooth ,thin slabs and 

has been prospected for commercial flagstone. The flagstone interval is 

overlain by a 7-foot massive bed of siliceous dolomite and, in turn, by a 

30-foot layer of thin- to medium-bedded limy siltstone. Th1s siltstone 

grades upward into a sequence 250 feet thick of very distinctive impure limestones that forms the central part of the section. The limestone 

is thin bedded, strikingly banded in shades of gray -and greenish gray, 

and highly micaceous. It has good bedding-plane cleavage and commonly a well-developed cleavage at a distinct angle to the bedding. The 

thin :bedding and color banding are the most distinctive characteristics 

of these beds. Many of the laminae react violently to dilute hydrochloric acid. Above this central part is a zone about 80 feet thick 

of thinly interbedded light-colored limestone and darker colored nonlimy siltstone, the limestone becoming predominant in the upper 10 

feet. A covered interval of 15 feet separates the limestone from ' a 

sequence of dolomite and silty dolomite that forms the upper 130 feet 

of the measured section. The upper dolomite is rather massive to medium bedded and fine to medium crystalline and contains silty laminae. 

Indistinct bedding lines are visible in the massive layers. The color is 

generally mottled gray to tannish gray; wea;thered surfaces are tan 

and light brown. The top of the dolomite at the measured section is 

separated from the overlying Cash Creek Quartzite by a zone of 

brecciated dolomite .and quavtzite that is heavily iron stained. Gossan 

has been developed in · some fractures and open spaces. Evidence for 

a fault semiparallel to the bedding is conclusive; the dolomite is 

gradually cut off along the fault south of here. However,' a fault is 

not apparent at the contact about one-half mile along the strike to 

the north, and the dolomite in the unfaulted section is comparable in 

thickness to the section just described. The original thickness of rthe 

dolomite is probably little more than that at the measured section. 

Thickness and age 

This predominantly carbonate-bearing sequence of rocks is at least 

570 feet thick. Its age is uncertain. The sequence· lies in apparent 
THE KINNIKINIC QUARTZITE OF CENTRAL IDAHO J21 

conformity below the Cash Creek Quartzite, but no fossils have 

been found in it, nor have any been found in the quartzite that lies 

below. 

LOWEB QUARTZITE 

Below .the carbonate sequence on Squaw Creek are quartzitic rocks 

that are known only at this locality, but like the other quartzites in 

the Bayhorse region, they may be represented among the numerous 

isolated quartzite masses of uncertain age that are scattered to the 

north and east. . , 

Most of this lower quartzite is light grayish orange to nearly white. 

Weathered surfaces are grayish orange to light brownish gray. The 

beds are medium to very thick, and many exhibit large-scale crosslamination. The component grains are generally unsorted and range 

from fine to coarse but are predominantly in the fine to medium range. 

Most of the grains are quartz, hut many of the beds contain numerous 

particles of white or orange clayey material that most probably results 

from the alteration o£ feldspar. A few thin layers of medium-gray 

1 aminated siltstone, notably micaceous, are distributed through the 

section. Beneath the massive quartzite which forms the upper several 

hundred feet of the section is a zone of mixed lithologies that contains 

some medium to thick beds of siltstone together with pebble-bearing 

quartzite, dolomitic sandstone, and coarse cleari pebble-bearing 

dolomite. One layer of blue-black coarse-grained dolomite contains 

conspicuous rounded quartz grains and pebbles. Some of the quartzite 

in this mixed-lithologies zone contains carbonate granules that weather 

out and leave a pitted surface on many of the outcrops. The base of 

the zone is not exposed, but the lowest outcrops show much brecciation 

of the quartzite and shearing in the siltstone and contain many quartz 

veins; all of these features suggest major structural disturbance. 

The exact position in the section and the thickness of the zone of mixed 

lithologies are uncertain because of the incomplete exposures and 

obvious structural disturbance, but the zone comprises several hundred 

feet of rocks below the massiv.e quartzite. 

The lower quartzite was not measured, but from the distribution and 

attitude it is estimated that at least 400 feet is exposed in the valleys 

of Boundary Creek and First and Second Creeks. The base probably 

rests on a major thrust fault. 

CONCLUSION 

Detailed studies in the Bayhorse region hav.e revealed that the 

Kinnikinic Quartzite established by C. P. Ross (1934) and mapped by 

him in the vicinity of the type exposures (1937) includes two different 

carbonate-bearing units and three or four distinct quartzite units of 
J22 CONTR"rBUTIONS TO STRATIGRAPHY . 

widely · different ages. The name Kinnikinic is here restricted to the 

youngest quartzite unit of the ori'ginal formation, arid three new 

formational names are introduced for older quartzite and dolomite 

units. The new subdivisions of Ross' original Kinnikinic occur in two 

stratigraphic sequences, represented by columns A, B, and-o of figure 

3. The stratigraphic and structural relations between these· sequences 

and the further delineation and regional correlation of the new units 

are subjects of continuing inv.estigation. 

REFERENCES CITED 

Anderson, A. L., 1961, Geology and mineral resources of the Lemhi quadrangle, 

Lemhi County, Idaho : Idaho Bur. Mines and Geology Pamph. 124, 111 p. 

Anderson, A. L., and Wagner, W. R., 1944, Lead-zinc-copper deposits of the 

Birch Creek district, Clark and Lemhi Counties, Idaho: Idaho Bur. Mines 

and Geology Pamph. 70, 43 p. 

Churkin, Michael, Jr., 1963, Ordovician trilobites from graptoUtic shale in central Idaho: Jour. Paleontology, v. 37, no. 2, p. 421-428. 

Mapel, W. J., Reed. W. H., and Smith, R. K., 1965, Geologic map and sections 

of the Doublespring quadrangle, Custer and Lemhi Counties, Idaho: U.S. 

Geol. Survey Geol. Quad. Map GQ-464. 

Patton, W. W., 1948, Geology of the Clayton area, Custer County, Idaho: .Cornell 

Univ. Masters •thesis. 

Ross, C. P., 1934, Correlation and interpretation of Paleozoic stratigraphy in 

south-central Idaho; Geol. Soc. America Bull., v. 45, no. 5, p. 937-1000. 

---1937, Geology and ore deposits of the Bayhorse Region, Custer County, 

Idaho: U.S. Geol. Survey Bull. 877,161 p. [1938]. 

---1947, Geology of the Borah Peak quadrangle, Idaho: Geol. Soc. America 

Bull., v. 58, no.12, pt.1, p.1085-1160. 

---1961, Geology of the southern part of the Lemhi Range, Idaho: U.S. Geol. 

Survey Bull. 1081-F, p. 189-260. 

---1962, Paleozoic seas of central Idaho : Geol. Soc. America Bull., v. 73, no. 

6, p. 769-793. 

Ross, R. J., Jr., and Berry, W. B. N., 1963, Ordovician graptolites of the Basin 

Ranges in California, Nevada, Utah,' and ·Idaho:· U.S. Geol. ·,Survey Bull. 

1134, 177p. 

Scholten, Robert, 1957, Paleozoic evolution of the geosynclinal margin north of 

the Snake River Plain, Idaho-Montana: Geol. Soc. America Bull., v. 68, no. 

2, p. 151-170. 

Shockey, P. N., 1957, Reconnaissance geology of the Leesburg quadrangle, Lemhi 

County, Idaho: Idaho Bur. Mines and Geology Pamph. 113, 42 p. 

Sloss, L. L., and Moritz, C. A., 1951, Paleozoic stratigraphy of southwestern 

Montana: Am. Assoc. Petroleum Geologists Bull., v. 35, no. 10, p. 2135-2169.