A SECTION OF THE PALEOZOIC FORMATIONS 0 THE GRAN.D CANYON AT 

THE BASS TRAIL. 

By L. F. NoBLE. 

INTRODUCTION. · I one place, a though some of them show the 

The :thick series of horizontal strata· of Paleo- lithology of one or two formations in detail. 

zoic age which makes the greater part of the Consequently none is adequate as a standard 

wall of the Grand Canyon is probably broadly for close an accurate comparison and corfamiliar to more people than the strata exposed relation of t e formations from place to place 

in any other area in the western United States. in the cany n or for a detailed comparison 

Each detail of form or color in the wall is so with Paleoz ic rocks exposed elsewhere in 

definitely associated with a bed or set of beds Arizona. · 

in the series that these strata are the very ele- Realizatio of this lack of detailed stratimerits of the canyon landscape. Consequently graphic infor ation has led me to undertake 

they have been described not only by geologists a more thoro gh study of the Paleozoic rocks 

·but by many writers who have been interested in the Grand Canyon than has been attempted 

in the Grand Canyon chiefly as a scenic spec- previously. his work, begun in 1914 and 

tacle. continued i 1916 and 1920, has supplied 

In few . areas, however, where the general material for fuller description of the strata 

character and succession of the rock formations than was he .etofore possible. · 

is so familiar are the details of the stratigraphy The prese t report includes a complete 

so "imperfectly known. In the Kaihab division columnar sec ion of the Paleozoic formations 

of the Grand Canyon, which lies within the bor- at the Bass trail, cblumnar sections of the 

ders of the Grand Canyon National Park and is Cambrian To to group at five other places in 

the best known and most visited part of the the I{aibab ivision, and a discussion of the 

canyon, sections of the Paleozoic formations age and cor elation of the Paleozoic formahave been measured at four different places- tions. Dr. alcott has kindly furnished from 

(1) at N unkoweap Valley, by Walcott; 1 (2) at his notes m terial for a fuller description of 

Congress Canyon (now known as Red Canyon), his section t Kanab Creek than has been 

along the Hance trail, by Frech; 2 (3) at published, a d I have used this material 

Bright Angel (Ca1neron) trail, by Darton 3 and freely in co paring and correlating the strata 

by me; 4 and ( 4) in the region about Shinumo exposed at Bass Canyon, in the Kaibab 

Creek and Bass Canyon, by me. 5 division, wit those exposed at Kanab Creek, 

None of these sections shows in detail the in the Kana division. I have also included 

lithology of all the Paleozoic formations at any in the report a section of the strata exposed in 

1 Walcott, c. D., u.s. Geol. Survey Tenth Ann. Rept., pt. 1, p. 584, Cedar Moun ain, a butte . on the Coconino 

1890. Plateau 2 m· es .east of the rim of the Grand 2 Frech, F., Section at Congress Canyon: Cong. geol. internat., 5• sess., 

Compte rendu, pp. 476-481, 1894. 8 Darton, N. H., A reconnaissance of parts of northwestern New Mexico 

and northern Arizona: U.S. Geol. Survey Bull. 435, p. 21, 1910; Guidebook of the western United States, Part C, The Santa 'Fe Route: U.S. 

G~ol. Survey Bull. 613, pp. 124-130, 1915. 4 Noble, L. F., The geologic history of the Bright Angel quadrangle, 

Ariz.: U. S. Geol. Survey Bright Angel topographic map. 5 Noble, L. F., The Shinumoquadrangle, Grand Canyon district, Ariz.: 

lJ. S. Geol. Survey Bull. 549, pp. 60-73, 1914. 

Canyon nea Tanner Canyon. This section 

carries the rand Canyon geologic column 

up into the Mesozoic. The strata in Cedar 

Mountain, w ich is capped by the Shinarump 

•conglomerat , of Triassic age, are the only 

remnants ne r the canyon rim of formations 

23 
24 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

that once covered the region but have been 

removed by erosion. 

A map of the Grand Canyon between Nunkoweap Valley and Kanab Creek (fig. 1) shows 

the localities cited in this report and indicates 

the position of most of the displacements that 

cut the Paleozoic strata in this region. A 

key map (fig. 2)' shows the localities where 

I measured the section at the Bass trail. 

The section at the Bass trail presented in 

this report (Pl. XIX) supplants the Paleozoic 

EXPLANATION 

I Bass trail 

2 Boucher trail 

3 Herm1t trail 

4 Cameron trail 

~ S Berry tra_il 

6 Hance (Red Canyon)trail 

7 Tanner trai.l 

section given in my report on the Shinumo 

quadrangle, 6 because, except for the Bright 

Angel shale, the section given in the Shinumo 

report is a generalized reconnaissance section 

and is inaccurate in detail, t.he thicknesses 

assigned to ·formations having been either 

estimated or obtained by means of rough aneroid measurement. Several of the formations 

described in the Shinumo report are herein 

redefined. 

e Noble, L. F., op. cit., pp. 60-73. 

Oi.=3:::::E:r:::::E:=Sr::.===::==IE0=:==:=::::::3'.15 MILES 

FIGURE 1.-Map of Grand Canyon, Ariz., between ~b Creek and Nunkoweap Valley. 
PALEOZOIC FORMATIONS OF THE GRAND CANYON. 25 

:FIGURE 2.-0utline map of area about Bass trail, Shinumo quadrangle, Ariz., showing localities where different parts of Paleozoic section were 

measured. Numbers correspond to those given in the detailed section. Dotted lines show cliffs as follows: T, Tapea:ts sandstone; R, 

Red wall limestone; S, Supai formation (uppermost cliff); C, Coconino sandstone. Hachures along rim of Grand Canyon and at Mount 

Huethawali show uppermost cliff formed by the Kaibab limestone. 
26 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

SECTION AT BASS TRAIL. 

The section of Paleozoic rocks at the Bass 

trail is given below in two forms-a brief section showing the major subdivisions and a detailed section with comments on the beds. 

Section of Paleozoic rocks at Bass trail. 

1. General section. 

CARBONIFEROUS SYSTEM. 

Kaibab limestone (Permian): 

A. Gray crystalline limestone, very fossiliferous 

and somewhat cherty, passing at base 

and top in to alternating beds of very 

cherty limestone and buff calcareous 

sandstone; forms cliffs and steep slopes. . 292 

B. Buff and reddish fine-grained sandstone, 

poorly consolidated and irregularly bedded, containing beds of sandy breccia 

near top; forms slope.................... 136 

C. Buff sandstone and limestone in alternating 

beds, passing at top into massive siliceous 

limestone; upper portion forms a strong 

cliff; central portion forms cliffs and 

ledges; lower portion forms a slope. . . . . . 134 

Coconino sandstone (Permian): 

Pale-buff, uniformly fine-grained sandstone 

characterized by crossbedding on a huge 

scale; presents the appearance of a single 

massive bed; forms the strongest and highest 

562 

cliff in the upper wall of the canyon........ 330 

Hermit shale (Permian): 

Deep brick-red sandy shale and fine-grained 

friable sandstone·; characterized in upper 

portion by concretionary structure; beds 

form slope .. __ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 

Unconformity. 

Supai formation (redefined; Permian(?) and Pennsylvanian): 

A. Alternating beds of red soft platy sandstone 

and buff hard croBB-bedded sandstone, 

forming a ledgy slope broken by small 

cliffs; paBBing do'Yn into reddish or purplish to buff fine-grained cross-bedded 

sandstone in heavy massive beds, which 

form a strong cliff..... . . . . . . . . . . . . . . . . . . 306 

B. Alternating beds of red friable shaly sandstone and maBBive cross-bedded calcareous 

sandstone including a few thin beds of 

limestone and a prominent bed of limestone conglomerate and forming a steep · 

ledgy slope broken by small cliffs; passing 

down into reddish to buff fine-grained 

calcareous sandstone in heavy beds 

separated by thin layers of limestone or 

red shale and forming a strong cliff.. . . . . . 439 

C. Alternating beds of red. shale, bluish-gray 

or purplish-gray limestone, and reddish 

to buff calcareous cross-bedded sandstone; paBSing down into alternating beds 

of red sandy shale and bluish or purplish- ~ray limestone containing red chert; form 

ledgy slope broken by small cliffs; outcrops of many beds concealed by talus.. 208' 

Unconformity (?). 

Red wall limestone (redefined and restricted; 

Mississippian): 

A. Bluish-gray massive crystalline limestone 

in distinct beds, some of which are separated by thin partings of red shale; forms 

a succession of small cliffs and ledges 

above sheer cliff of subdivision B...... 62: 

B. Bluish-gray massive crystalline limestone 

in beds whose planes of separation are 

inconspicuous, so that when seen from a 

distance much of the limestone presents 

the appearance of a .single massive stratum; forms sheerest and most sharply 

defined cliff in the canyon wall; thickness estimated. . . . . . . . . . . . . . . . . . . . . . . . . ±50(} 

C. Brecciated limestone; forms slope under cliff 

of subdivision B... . . . . . . . . . . . . . . . . . . . . . S. 

I 

Unconformity(?). 

DEVONIAN SYSTEM. 

Temple Butte limestone: 

Thin-bedded buff and pale-purplish sandy magnesian limestone; more or less blotched and 

mottled; harder, more massive beds alternate 

with softer, morJ conspicuously laminated 

beds; forms ledgy slope broken by small 

±570 

cliffs...................................... 75 

Unconformity. 

CAMBRIAN SYSTEM (TONTO GROUP). 

Muav limestone: 

A. Buff massive dolomite; forms strong cliff. . . 6~ 

B. Buff fine-grained calcareous sandstone; 

massive at top, thinly l~minated and in 

part micaceous and quartzose near base; 

forms cliff ... ; ........ - . . . . . . . . . . . . . . . . 7'!;, 

C. Alternating thinly laminated beds of impure 

mottled limestone, intraformational conglomerate, platy fine-grained micaceous 

sandstone, and calcareous sandstone; 

form steep slope ................. •. . . . . . 241 

D. Gray to buff hard thinly laminated mottled 

limestone; contains partings of greenish 

sandy shale for 10 feet at base i forzns cliff. 97 

Bright Angel shale: 

A. Thin-bedded greenish and buff micaceous 

shale and sandstone with interbedded 

layers of impure mottled limestone and 

glauconitic snuff-brown dolomite at the 

473 

base; beds form steep slope or weak cliff. . 58 

B. Thin-bedded greenish and buff micaceous 

shale and sa~dstone with two beds of 

snuff-brown dolomite and sandstone in 

the. middle p6rtion which form two conspicuous brown cliffs in a long slope made 

by the shales and sandstones. . . . . . . . . . . . 333 

391 
U. S. GEOLOGICAL SURVEY 

SE:CTION IN CANYON OF KANAB 

CREEK BETWEEN SHINUMO CA ~...<_ _ 

YON ANO em ni'?AOO RI~ER r~-- -- - _ -

Fe: ET r-l~B~Y A, /SOft. ~-r~?~lidw w/,_.A~i; vratchert,y ~ ·,.;. r' n~r~T~~·~~~ lime· --------:-----==-==~U~p~>p~e~r~Lower p:o:r:t:i~o:n portion K.~a~n:a~b~s;~ect cSto :on . ~Oto.JS miles NW. _ $tDne. Chert l ight colo~d, vOm,Je$ N w. - wed lhering black. Upper 

r;pr, on• v!~ry;~,.-U _ ____ _ _ 

4

,000- n. ~ 250ft Ma~i e ~ ., ·~ 

O

::l .s tone. C.her tin nodulei~~~ 

out cmtral ~rtion; a/~ in':";~:, 0:: lal'erv coinc/dent wit~ tiM oecr 

I..!J d ng at summit and base. 

-

3,500 -

-

-

3,000-

-

Very· fossil iferous: 

Pr-odu.ctU£ ive~ i, ei:c. 

D 12Sft. Alternating layers of 

l/!;p sum and light -colored 

. riable sandstone. 

A2- 270 ft. 

bedded bright:red = ·"· '""" 

passmg own 1nto evenJ.r 

bedded layer.s 30ft. from 

the top. 

IA3, cS_Dft. n,;, 5 1tatv• of gray sandst.one bysomewhdt massive layers of deeP.· red 

sandstone with p~rtm s of fri I h~ly- .,t:! n r:d ln- Ler calat.ed 7;;~yer::> cf gray :,an-.1 · , :;tone near t he ca e. · 

........... - ~ (Section di.swn mued at • ol 

-.._.. cr I ~:~s/l'lzt~~~~)"ed 

,500-~~Sft. A co .,~~=v ~ and,;~ ';'_ UJ•t ,.dl-';;.;rt.-

~~~~t~':t~~~~· ift. thick. occur at ri- zons . 

- Q:: 

-

w 

~ - 0 

..J 

.... _ -- .- 1-------~ :r"f--+'~-

2,00o1,500 

- ...1 

...1 

- ~ 0 

w 

0:: 

1,000-

- a. 

:::> 

0 

500- ~ 

- :: 

z 

0 - t-

-

c, 16 0 .'L 11/t'en"laliM 

and red s.o.nd,5tone.s:- friable than-8-. 

~~~gtt.5 G£f,{J:.~~i<buff calc/- ./ /' 

I q, tsp_fJ~C!~d~~ZDe~~fme- stone,m-?~5,-veatbese and 

t.opj .s_reni:/ceous haly_ partmg~ occt.Jr cJt vanous 

ho,.;zons; many beds con- sist in part of small flat -

tened limestone fr<-~ci!_tne• tsJ 

Fo ssils: Pttychopa ria, 

Ba.tJ 1.-YT.J r 1 lS, Ling tda., efL• 

/ 

/ 

/ 

/ 

/ / 

/ Tonto c liff 

!¥ C(Jmpiled from published reporc 

o- and unpubfl heel notes 

/ 

/ 

--------- ? 

/ / 

/ 

__ p -

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

1::1 

1/ I 

-·- - 7 

1·:: 

·l 

;,;-; 

A,tpflj, 

£!,7?f't. 

.. ·~ 

nn8'l -:n, .~in. 

. ".Y"' 

q!J7ft: 

•u vu•' '""'-~ ~ 

PROFESSIONAL PAPER 131 PLATE XIX 

SECTION AT BASS TRAIL W ITH PARTIAL SECTIO NS AT HERMIT TRAIL INSERTED TO SHOW STRATIGRAPHIC 

FEATURE S THAT ARE OBSCURE OR L ACKING AT BASS T RAIL. BY L .F. NOBLE. 

DIAGRAMMATIC PROF ILE, 

THICKNESS,ANO LITHOLOGIC 

_ --__ --•~ 1--'C"-H"-A"-R-'-A.:..:C:...:Tc.::E::.R:__._:O:...:F.......::S...:.T_R_A_TA_ 

~ SECTION AT BASS TRAIL 

~~R FACE ~f}:.ocON INO !"Lf'_T~ 

f..--t2.Smiles NW. -• 

~ 332ft. 

n .• ~~brick-red 5af!dy 

~~-- ·-.-{'·"'"" .:~; ·,'~ II : ~~''"~·' ~~and fine ·tfrarned ·v sandsfDn~.- . \ 

port.'on chardc -~ ~..:;: zed IYy concretion 

/- '- -=- ary structure. 

? 

..I 

;'(e)'J ·o 

l 

GROUP 

AND 

fORMATION 

Kaibab 

limestone 

Coconino 

sandstone 

Hermit 

shale 

Supa i 

forrnation 

Redwa ll 

l im estone 

r-e 

I 

Muav 

llim<>c:.tnn 

Bright 

Angel 

shale 

Unkar ~roup of 

Grand Canyon 

series resting un 

conformablY on 

Archean ~r.:rnite, 

gnei5s,anCf schist 

0 

z 

0 

CD 

u 

z 

<{ 

a:: 

u 

COLUMNAR SECTION OF THE PALEOZOIC STRATA OF THE GRAND CANYON AT BA TRAIL 
PALEOZOIC FOR.MATIONS OF '!'HE GRAND CANYON. 27 

Tapeatf} sandstone: 

A. White cross-bedded sandstone; forms weak 

cliff.......................... . ......... 35 

B. Chocolate-colored sandstone with partings 

of shale; forms steep ledgy slope. . . . . . . . 43 

C. Massive chocolate-colored cross-bedded 

sandstone; forms sheer cliff along rim of 

Granite Gorge. . . . . . . . . . . . . . . . . . . . . . . . . . 250 

328 

Total thickness of Paleozoic rocks...... ±4,014 

2. Detailed section. 

Kaibab limestone: 

A. 1. Limestone, buff, compact; effervesces 

strongly with dilute hydrochloric acid; 

caps a small cliff on the rim of the 

canyon at the head of Bass trail. Bass 

Camp, on the Coconino Plateau, at 

the head of the trail, is built upon this 

stratum. Higher beds, which form 

the surface of the plateau just east of 

the camp, are not included in this 

section.............................. 2 

2. Limestone (for analysis see p. 69), buff, 

siliceous; texture compact, chalky; 

contains small cavities lined with tiny 

crystals............................. 6 

3. Sandstone, buff, fine grained, calcareous; effervesces with acid ........... : 5 

4. Alternating thin beds of variegated chert 

and fine-grained calcareous sandstone. 25 

5. Limestone, gray, crystalline, very cherty, 

fossiliferous. The chert occurs in nodules and in bands; in places it constitutes half of the rock. - Aside from 

the abundance of chert the limestone 

resembles No.6...................... 40 

6. Limestone (for analysis seep. 69), gray, 

hard, crystalline, somewhat cherty, 

very fossiliferous; effervesces strongly 

with acid; Beds differ greatly in 

thickness; some are a few inches thick, 

others several feet. The chert occurs 

in scattered nodules and in bands but 

is not a conspicuous feature of the 

rock................................ 126 

7. Alternating beds of fine-grained buff 

calcareous sandstone, buff limestone, 

and chert; form small conspicuous cliff. to 

8. Limestone, gray, hard, crystalline, somewhat cherty, fossiliferous; like No.6.. 60 

9. Sandstone, lemon-buff, fine-grained, calcareous; bedding irregular, gnarly; 

forms a gentle slope covered in most 

places by talus ...... ___ .............. 10 

10. Limestone, thin-bedded, very cherty; 

effervesces with acid. The chert constitutes over hal'! of the rock and occurs 

in parallel bands whose average thickness is 2 inches. . .. . . .. .. . . . . . . . . . . . . . 8 

292 

[NoTE.-The foregoing section of subdi-= 

vision A was measured .under the rim 

of the canyon directly in front of Bass 

Camp, at locality 1, figure 2.] 

B. 1. Sandstone, buff, massive, fine-grained, 

ca~careous; effervesc_es weakly with 

ac1d ......................... __ . _ ... . 

2. Breccia composed chiefly of angular 

fragments of evenly bedded buff finegrained sandsto:he embedded in a 

matrix of fine lemon-buff sand; con-· 

tains a few fragments of siliceous limestone. The fragments range in diameter from less than an inch to over 4 

feet. The contact of the breccia with 

the underlying sandstone is wavy and 

irregular, exhibiting in places inequalities of several feet ............... . 

3. Sandstone, buff, fine-gra~ned, friable. 

The. component grains are quartz, as 

in other sandstones of the Xaibab, 

but are very loosely cemented, so that 

the rock crumbles to sand when struck 

with the hammer .................... . 

4. Sandstone like No. 3, but bright red ... . 

5. Buff sandstone like No.3 .............. . 

6. Bright-red sandstone like No: 4 ........ . 

7. Lemon-buff sandstone like No. 3 ....... . 

8. Bright-red sandstone like No. 4; contains a l-inch layer of pale~green sandstone in the central portion .... ~ ..... . 

' 9. Sandstone, lemon-buff, fine-grained, friable; bedding irregular, gnarly; contact with underlying sandstone slightly 

wavy and irregular .................. . 

10. Sandstone, bright red, shaly; bedding 

gnarly; contact with underlying breccia wavy and irregular, exhibiting in· 

equalities of 2 feet or more ............ . 

11. Breccia composed of angular fragments 

of fine-grained sandstone averaging 4 

inches in diameter. Very little matrix between the fragments. The 

appearal).ce of the rock suggests that 

it was crushed and shattered after it 

was deposited. The contact with 

the underlying sandstone is irregular, 

exhibiting inequalities of several feet .. 

12. Reddish-buff, loosely consolidated finegrained sandstone in indistinct but 

fairly even. beds, some of which display 

gnarly structure; forms debris-covered 

slope; exposures poor. The upper 3 

feet of the sandstone is bright red arid 

thinly lamin~ted ... ~ ............... . 

13. Sandstone like No. 12 but more compact, forming a weak cliff; gnarled 

and twisted structure very pronounced; 

color lemon-buff to reddish buff ...... . 

14. Sandstone like No. 12, very soft, forming a gentle slope that is covered 

nearly everyrhere by talus; no good 

exposures obtainable. Colored white, 

lemon~buff, greenish, and bright red. 

In some places the color is in blotches 

or streaks; in others a single color 

4 

17 

1 

2 

8 

2 

5 . 

7 

3 

4 

1() .. 

10 

characterizes each bed. .. .. .. . . . . .. . . 58 

136 
28 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

[NoTE.-The foregoing section of subdivision B was measured on the northeast side of Fossil Mountain, at locality 2, figure 2.] 

C. 1. Limestone, buff, dense, siliceous; in 

heavy, massive beds; forms a strong 

cliff; contains much chert in bands and 

nodules and many small cavities lined 

with crystals of quartz or calcite. In 

appearance the rock suggests silicified 

chalk. Some beds effervesce weakly 

with acid ...... ~ .•.................. 

2. Limestone like No.1 but in thinner beds 

(1 foot or less) which are separated by 

thin partings of buff fine-grained shaly 

sandstone; forms a steep ledgy slope ... . 

3. Limestone like No. 1; forms a cliff ..... .. 

.4. Shaly sandstone, lemon-buff, soft, thinbedded, fine-grained; makes alcove 

under overhanging cliff of No. 3 ...... . 

5~ Limestone, buff, in heavy beds with 

thin sandy partings, not notably siliceous; effervesces strongly with acid; 

forms cliff ........................... . 

6. Shaly sandstone like No.4; makes alcove 

under overhanging cliff of No.5 ....... . 

7. Limestone like No. 5 but in thinner beds 

(1 foot or less); forms slope ............ . 

8. Limestone, buff, dense, siliceous, in 

heavy beds; contains numerous crystallined cavities apparently formed by 

the solution of brachiopods; does not 

effervesce with acid ... -.· ............ . 

9. Limestone like No. 7, in beds separated 

by very thin partings of sand .......... . 

10. Sandstone, ·buff, fine-grained .......... .. 

11. Limestone like No.7, but in a single bed. 

12. Sandstone, buff, fine-grained .......... . 

13. Limestone, buff, siliceous, fossiliferous; 

does not effervesce with acid; contains 

numerous small cavities lined with calcite crystals ......................... . 

14. Alternating beds of lemon-buff finegrained sandstone and buff limestone; 

beds average 3 inches in thickness .... 

15. Limestone, buff, not notably siliceous; 

effervesces strongly with acid ........ . 

16. Sandstone, lemon-buff, fine-grained ... . 

17. Sandstone, red, fine-grained. The base 

of this layer truncates inclined laminae 

of the underlying Coconino sandstone, 

Coconino 

which dip 15° S ................ _. __ . 

[NoTE.-The foregoing section of subdivision C was measured directly 

above the point where the Bass trail 

descends the Coconino sandstone, at 

locality 3, figure 2.] 

sandstone: Pale-buff fine-grained sandstone, cross-bedded on a huge scale; 

appears like single massive .bed; forms 

highest cliff in upper wall of canyon. 

The base of the sandstone is marked by 

an abrupt change from buff sandstone 

to underlying red shale, and the contact is an even line. In places the 

48 

12 

16 

2 

g. 

11 • 

5 

5 

1! 

6 

6 

! 

2 

! 

134 

[ under surface of the sandstone shows 

impressions of sun cracks. For 25 feet 

above the base the moss-bedding is on 

a small scale, and horizontal layers 

alternate with cross-bedded layers; 

then the coarse cross-bedding begins 

and continues upward until the sandstone is truncated by the level base of 

the Kaibab ........................ . 

[N OTE.-The foregoing section of the Coconino sandstone was measured on the 

Bass trail at the point where the trail 

descends the sandstone, at locality 3, 

figure 2. At Mount Huethawali, a 

mile northwest of this point, the basal 

layer of the Coconino is massive sandstone 5 feet thick which displays no 

cross-bedding.] 

Hermit shale: 

1. Sandstone, red, soft, fine-grained, massive, with a thin layer of green shale at 

the top. Exhibits well-marked concretionary structure; the concretions 

are spheroidal forms which range from 

half an inch to 4 feet in diameter and 

consist of the general mass of the rock; 

in weathering, the rock splits off in 

concentric shells along the concretionary surfaces ......................... . 

2. Sandstone, fine-grained, massive; resembles the Coconino sandstone in texture 

and compositiOn but is not crossbedded; lower half buff; upper half 

red With buff blotches ............... . 

3. Concretionary sandstone like No. 1, in 

massive layers ..................... . 

4. ·Shale, deep red,. thinly la-minated, sandy. 

5. Beds of soft massive concretionary red 

sandstone like No. 1 alternating with 

thinner beds of deep-red shale like No. 

4 · sandstones and shales not conspicu~usly different in composition ..... . 

6. Shale, deep red, sandy ....... -- ....... -

7. Sandstone, pink, hard, very fine grained; 

contains cracks and cavities filled with 

crystals of calcite (dog-tooth spar); rock r 

itself does not effervesce with acid; 

forms small prominent cliff .......... . 

8. Shale, soft, brick-red, thinly laminated, 

sandy ....... - -..... ---- - - . -- . - . - . - . · 

9. Sandstone, brick-red, friable, massive; 

forms weak cliff .................... . 

All underlying beds of shale are like 

No. 8; all underlying beds of sandstone like No.9. The beds designated 

shale and sandstone actually differ 

little in composition; both consist essentially of sandy mud colored red by a 

strong .ferritic pigment. The beds 

designated sandstone are massive and 

relatively compact, as contrasted with 

the beds designated shale, which are 

thinly laminated and soft. Both types 

of rock are friable. 

330 

5 

6 

16 

24 

28 

16 

6 

28 

2 
P ~LEOZOIC FORMATIONS OF THE GRAND CANYON. 29 

10. Shale, containing beds of massive friable 

sandstone near the top............... 33 

11. Sa!}.dstone in massive beds; contains a 

1-foot layer of shale in the middle portion; forms weak cliffs.... . . . . . . . . . . . . ·s 

12 Shale ......... ________ .......... ___ . _ _ ll 

13. Sandstone; forms weak cliff .......... _ _ 10 

14. Shale ................ :................ 33 

15. Alternating lenticular beds of intraformational conglomerate and red finegrained sandstone averaging 1 foot in 

thickness; beds display indistinct sun 

cracks and rain prints; form weak cliff. 

The conglomerate consists chiefly of 

flattened pebbles of fine-grained sand-

·stone or sandy shale less than1 inch in 

diameter embedded in a matrix of red 

sandy mud but contains some nodular 

or concretionary fragments of limestone 

16. Shale ..................... : . ......... . 

17. Sandstone .... ·-----~---·······-------

18. Shale ............................. .. 

19. S:1ndstone ..... · ...................... . 

20. Shale ... " .......... .' ................. . 

21. Sandstone;. forms weak diff ........... . 

22. Shale ................................ . 

23. Sandstone; forms weak cliff ........... . 

24. Shale ..... : .................. .- ....... _ 

6 

ll 

3 

40 

2 

6 

5 

16 

5 

12 

332 

[NoTE.-The foregoing section was meas----

ured at the east end of Mount Huethawali, about a quarter of a mile north- 1 

west of the point where the B~ss trail 

begins to descend into Bass Canyon, at 

locality 4, figure 2.] 

Supai formation: 

A. 1. Sandstone, white, fine-grained, crossbedded, hani, calcareous; effervesces 

with acid; contains many cracks lined 

with calcite; forms a small conspicuous 

cliff and determines a wide shelf at 

the general level of· t4e Esplanade 

platform. At the point where the section was measured the floor of the Esplanade consists in part of this sandstone and in part of knolls of soft red 

Hermit shale which overlie the sandstone .......................... _ . . . . 2! 

·2. Sandstone, red, soft, friable, platy, finegrained; forms a long, gentle slope_ .. _ 16 

3. Sandstone, buff, fine-grained, massive, 

weathers white; effervesces with acid; 

unites with underl}ring bed in forming 

a cliff .. . · ............ _ . . . . . . . . . . . . . . 1 1 

4. Sandstone, pinkish buff, cross-bedded... 5! 

5. Red soft platy sandstone like No. 2; 

forms slope .......... , ........ __ . . . . 4! 

6. Massive buff sandstone like No. 3; hard; 

forms strong cliff ...... _ ............ ; 12 

7. Red soft platy sandstone; forms slope .. _ 7 

8. Pinkish-buff cross-bedded sandstone like 

No. 4; forms cliff ................ .:.... 5 

91048°-23--3 

A. 9. Soft platy beds of red sandstone alternating with harder, more massive beds; 

form long ledgy slope .... _._... . . . . . . . 44 

10. Pinkish-buff cross-bedded sandstone; upper surface weathers white; forms cliff. 101 

11. Red soft platy sandstone; forms wastecovered slope. . . .......... ·. . . . . . . . . . · 6 

12. Pinkish-buff cross-bedded sandstone; 

forms cliff . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

13. Red soft platy sandstone; forms wastecover'eci slope ............. : . . . . . . . . . 15 

,14. Fine-grained sandstone in heavy, massive 

~eds, some of whtch are separated by 

thin partings o.f red soft platy sandstone; cross-bedded throughout; inclined laminae dip south; some beds 

near ·the :base display · an irregular, 

gnarly structure. The prevailing color 

of the upper 40 feet of the sandstone is 

. pale brick-red; that' of the lower 125 

feet ranges from pale purplish to buff. 

The rock of most beds dd'es-!ot effervesce with acid. · A be9- of sandy 

limestone or very calcareous sandstone 

2 feet thick o<;cms 35 feet above the 

base of the sandstone... . . . . . . . . . . . . . . . 165 

A. 15. Conglomerate, compOsed of subangular 

fragments of sandstone embedded in a 

matrix of fine sand of the same c6mpo- . 

sition as the fragments; probably an 

intraformational conglomerate; displays a rude concretionary structure; 

fntgments weather by splitting · off in 

concentric shells. ·Many of these shells 

are embedded in the matrix. The conglomerate varies in thickness and in 

places is absent; appears to rest upon a 

slightly uneven surface.. . . . . . . . . . . . . 0-5 

[NoTE.-At .the rim of Bass Canyon directly east of Mount Huethawali subdi- • 

vision A of the Supai is cut by a fault 

which breaks the str~ng cliff formed by 

bed 14. The Bass trail descends the 

cliff in a shattered zone a 1ong the fault. 

The strata have been displaced about 

130 feet by the fault, those on the east 

side being relatively lowered. In 

measuring subdivision A at Bae:s trail 

it was necessary to divide the section 

at the fault. Beds 1 to 13 and the 

upper 40 feet of bed 14 were measured 

west of the fault, in the slope between 

the trail and the base of Mount Huethawali, at locality · 4, figure 2. Bed 

15 and the lower 125 feet of bed 14 

were measured on the trail just east 

of the fault, at locality 5, figure 2. 

The thickness which I have assigned 

-to bed 14 may be incorrect, because I 

could not locate equivalent layers in 

306 
30 SHORTER CONT1{IBUTIONS TO GENERAL GEOLOGY, 1922. 

the bed on opposite sides of the fault, 

owing to the homogeneity of the sandstone.l 

B. 1. Magenta or reddish platy fine-grained 

shaly calcareous sandstone; effervesces 

with acid; forms slope ......... ___ ·- __ 

2. Hard massive sandy limestone or very 

calcareous sandstone; effervesces 

strongly with acid; unites with underlying bed in forming cliff. __________ _ 

3. Gnarly sandstone blotched purpliSh and 

buff. ______________ ._. _______ . ___ . __ 

4. Red friable sandstone; forms slope -- --

· 5. Buff cross-bedded calcareous sandstone; 

forms cliff. ______ ______ . _____________ _ 

6. Red friable shaly sandstone ; forms slope. 

7. Alternating lenticular beds of conglomerat~ and fu?.e-grained sandstone, both 

cro~-beddfild. Most of the conglomerate coW,ists of well-rounded waterworn pebbles 4 inches or less j.n diameter embedded. in a matrix of red mud 

and sand; most of the pebbles are 

bluish-gray or p1Jrplish-gray nodular 

limestone, bu.t some are fine-grained 

sandstone. Some beds exhibit the 

peculiar concretionary structure that 

characterizes bed 15 of subdivision A 

. and consist of subangular fragments of 

sandstone ranging from less than 1 inch 

to more than 2 feet in diameter embedded in sand of the same composition as the fragments. The beds of 

conglomerate and sandstone rest on an 

uneven surface that exhibits a relief of 

several feet._ .. _ . _ ... _ ... __ . _ ...... _ . _ 

8. Red friable shaly sandstone ; forms slope. 

9. Pinkish-buff cross-bedded calcareous 

sandstone; unites with underlying bed 

in forming cliff .... _ . _ . _ . _ . _ ..... ___ . 

10. Pink hard massive sandy limestone or 

very calcareous sandstone ; effervesces 

strongly with acid._ . _ ............... . 

11. Red friable soft sandstone ; exhibits con-

. cretionary structure; forms slope ... _. : 

12. Buff cross-bedded sandstone ; forms cliff. 

13. Beds of red shale and soft concretionary 

calcareous sandstone ; form alcove 

under cliff of No. 12 ......... : ..... . 

14. Light brick-red to pinkish-buff, rather 

· soft cross-bedded calcareous sandstone 

with a few interbedded layers of red 

shaly sandstone; forms a steep ledgy 

slope broken by weak cliffs; some beds 

contain elongated rudely cylindrical 

or conical forms which are lighter in 

color than the mass of the rock and in 

places weather out of the rock. These 

forms are of various sizes, but m~st of 

the~ are less than 1 inch in diameter. 

They are undoubtedly organic.in origin and may be fucoids ... _ ......... . 

30 

2 

5 

5 

10 

11 

28 

10 

18 

3 

8 

20 

6 

80 

B. 15. Red friable soft thinly laminated sandstone; forms slope .... __ ... _ .......... . 

16. Massive sandy limestone or very calcareous sandstone; rests on a slightly uneven wavy surface that truncates inclined laminae of the underlying sandsto.ne; caps cliff formed by the underlying sandstone ..... _ ............... . 

17. Buff fine-grained cross-bedded calcareous 

sandstone; effervesces with acid. The 

cross-bedding is on a coarse scale; s.everal wedges exceed 30 feet in thickness, 

and one wedge, exposed at the 4,857-

foot bench mark on the Bass trail, is as 

thick as the entire bed. The. Bass 

trail descends the bed on the inclined 

laminae of this wedge; inclined laminae in all wedges dip south; curvature 

of laminae not a conspicuous feature; 

angular type of cross-bedding appears 

to prevail; bed forms strong cliff ..... 

18. Alternating beds of red friable calcareous 

sandstone and maroon soft thinly laminated ~hale; form ledgy slope. __ ..... 

19. Light brick-red calcareous sandstone; 

effervesces strongly with acid; contains 

elongated cylindrical or conical forms 

similar to those in bed 14 and numerous obscure small branching forms 

which may represent either fucoids or 

worm burrows; makes a ledgy slope. __ 

20. Nodular purplish-gray limestone; contains large numbers of the obscure 

forms noted in bed 19; caps cliff 

formed by underlying bed .......... . 

21. Buff cross-bedded calcareouf! Stl,ndstone; 

like No. 17, but the cross-bedding is on 

a less coarse scale; forms strong cliff ... 

22. Beds of calcareous sindstone blotched 

red and buff separated by thin beds of 

maroon shale which exhibit suncracked surfaces; form alcove under 

cliff of No. 21. The Bass trail follows 

.. this alcove southward to ~ gulch in 

which it descends a long rock slide to 

the base of the Supai .. . ............ . 

23. Hard pinkish or purplish fine grained 

limestone blotched greenish buff; 

crystalline in places; contains the obscure forms noted in bed 19, also small 

masses, largely calcite, whose outlines 

suggest those ·· of brachiopods; with 

underlying beds forms strong cliff. __ 

24. Beds of pinkish fine-grained limestone; 

form clifi. _ .............. _ ........... . 

25. Buff cross-bedded calcareous sandstone 

like No. 21; forms cliff ........... _ .. . 

26. Red shale; forms small alcove ____ ...... . 

27. Buff cross-bedded calcareous sandstone 

like No. 21, divided into two beds by 

a thin parting of red shale in the center; forms strong cliff. The under 

10 

3 

44 

28 

6 

1 

20 

6 

3 

10 

35 

1 
PALEOZOIC FORMATIONS OF TRE GRAND CANYON. 

surface of the lower sandsrone bed exhibits casts of sun cracks a.t the contact 

with the underlying shale •...... ~ . ~ . . 34 

B. 28. Maroonsh.ale............................ ! 

29. Massive buff calcaroous sandstone; baBe 

slightly uneven, wavy .......... l .... 1! 

439 

· C. 1. Bluish-gray nodular limestone mixed--

with red mud which imparts a blot!ched 

or mottled appearance to the rock. . . . 1 

2. Maroon shale; exhibits concretionary 

structure; in part brecciated; d-ac!rs 

between fragments infiltrated !with 

red mud; contact with underlying be$1 

uneven, wavy ..................... . 

. 3. Bluish-graynodularlimestonemixedlwith 

purplish mud, some of which appears 

to have 'been infiltrated along cr~cks; 

in part brecciated; contains th1 obscure forms, probably fucoids, noted 

in B 14, 20, and other beds ...... J. .. . 

[N OTE.-Beds B 28 and 29 and C 1, 2, 

and 3 form an alcove under the cliff 

at the base of subdivision B. I The 

foregoing section, including all of 1sub- · 

division B and beds 1 to 3 of subaivision C, was measured on or near1 the 

Bass trail on the west side of BaBS 

Canyon, at locality 5, figure 2.] \ 

4. Slope covered by talus, largely concealing 

underlying rock. Exposed beds consist of purplish platy calcareous s~ndstone or sandy limestone, blotched 

buff, separated by thin layers ofl red 

· shale ........................... -\-.. . 

5. Pinkish-buffhard cross-bedded calcareous 

sandstone; forms cliff .• _._._._ . __ I ___ • 

6. Red platy sandy shale .................. . 

7. Bluish-gray compact crystalline chfrtY 

limestone passing downwar<J. into nard 

cross-bedded calcareous sandstone; 

forms cliff ........................... . 

8. Cross-bedded calcareous sandstone Mth 

a 2-inch layer of red shale at the base; 

forms steep slope. . . . . . . . . . . . . . . . . . . .. 

9. Purplish sandy limestone; unites 'fith 

underlying bed in forming a cliff; r ontact with underlying bed uneven, exhibiting inequalities of 2 feet in places. 

10. Hard cross-bedded calcareous sandst~ne. 

11. Red soft shaly sandstone; in part crossbedded; forms a weak cliff .......... . 

12. Red sandy shale.; forms slope ..... ·j· .. 13. Bluish-gray limestone with conspic ous . 

bands of reddish or pink chert; in 

places the limestone is mixed with :reddish or purplish mud, which impar~s a 

mottled appea_i-ance to the rock .. -J- .. 

14. Red sandy shale, forms slope ......... . 

15. Purplish sandy limestone, in part crystalline; ·contains a few nodules of ~ed chert; forms slope _______ . _______ I __ _ 

16. Red soft fine-grained shaly sandstonj in 

platy beds; forms slope ..... _ .. _ .... 

2-4 

3 

28 

10 

3 

14 

11 

1-3 

2-4 

30 

22 

2 

4 

5 

6 

C. 1,7. Buff hard fine-grained calcareous sandstone; forms strong cliff ...... · ...... . 

18. Buff fine-grained shaly sandstone; in 

part conglomerate composed of lumps 

of chert and buff· sandy limestone 

averaging an inch in diameter; fonns , 

slope .........•.. - -· .... - - - . - . - - - - - -

19. Red shale; forms slope ................ . 

20. Bluish-gray limestone containing parallel 

bands of red chert ........ ~ ..... - -.. - -

21. Purplish massive friable sandy shale 

speckled with small circular buff spots, 

passing down into bluish-gray nodular 

cherty limestone ................... -

22. Gnarly nodular bed composed of lumps of 

purplish sandy shale mixed with purplish mud ..... -.·------------------

23. Conspicuously banded bed composed of 

bluish-gray limestone and white or red 

chert; forms strong cliff; the alternating bands of chert and limestone average an inch in thickness; in places the 

limestone at the summit of the bed is 

mixed or infiltrated with red mud .... 

24. Gentle slope covered by talus which conceals the bed so completely that no 

outcrops can be found .. The bed 

appears to be a reddish or purplish soft 

, j shale ... _ ......................... . 

[N OTE.-The foregoing section was measured on the east side of Bass Canyon a 

quarter of a mile northeast of the point 

where the Bass trail descends a break 

in the Redwall cliff at the head of the 

canyon, at locality 6, figure 2. This. 

break is on the line of ~ fault along the 

axis of Bass Canyon. The strata are· 

displaced about 75 feet by · the fault, 

those on the west side of the canyou. 

being relatively lowered.] 

Red wall limestone: 

A. 1. Bluish-gray massive limestone in heavy 

beds; contains a few scattered nodules 

of chert; forms strong cliff ........... . 

2. Red, purple, or greenish-buff shale; 

thinly laminated; forms slope ........ _ 

3, Beds of bluish-gray limestone separated 

~n places by paper-thin partings of red 

shale; form steep ledgy slope .. _ .. _ ... 

4. Bluish-gray limestone and red shale in 

alternating beds which average 1 inch 

thick; form slope ......... _· ..... __ .. . 

5.' Crystalline limestone; white on freshly 

broken ·surfaces; effervesces strongly 

with acid; contains a few chert nodules 

and here and there a poorly preserved 

fossil (see pp. 56-57); forms strong cliff. 

6. Bluish-gray crystalline limestone in beds 

less than 6 inches thick separated by 

paper-thin partings of reddish or buff 

31 

9 

5 

12 

2 

r 

14 

208. 

38 

1 

7 

2 

6 
32 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

sandy shale; wastes back in a slope, 

leaving a ledge at the summit of the 

sheer cliff of subdivision B........... 8 

62 

[N OTE.-The foregoing section was meas----

ured on the east side of Bass Canyon 

directly under the place where subdivision C of the Supai was measured, 

at locality 6, figure 2.] 

B. Massive crystalline limestone forming a sheer 

high cliff; upper portion heavily and 

obscurely bedded; middle portion distinctly bedded and containing many 

thin interbedded layers of chert and 

sand; lower portion heavily bedded 

and :nagnesian. ·Most beds contain 

scattered nodules of chert. Many contain coarse crystals of calcite; some of 

the calcite lines cavities; some of it 

occurs in large masses in the rock; 

some of it forms beds several inches to 

a foot thick. Intercalated layers of 

sand are commonly less than a foot 

thick, are loosely cemented, and exhibit gnarly structure; most of them 

rest on irregular, wavy surfaces. In 

many places the limestone cliff is 

stained pink by ferritic pigment 

washed over it from overlying red 

shales; unstained surfaces of the limestone weather bluish gray; freshly 

broken surfaces are gray, buff, or white. 

Subdivision B is rudely divisible into 

three members, as follows: 

1. Obscurely bedded limestone, most of 

which is in heavy beds; beds differ 

greatly in thickness, some being over 

20 feet thick, others only a few inches; 

most of the limestone is finely crystalline, light gray or white on freshly 

broken surfaces, and very pure (for 

analysis see p. 55) ; effervesces strongly 

with acid. Contains a few thin beds of 

sand, some chert, and much calcite in 

coarse crystals. Surface of limestone 

at top of cliff exhibits very poorly preserved fossils. · Thickness estimated·.. ±200 

2. Distinctly bedded limestone in rather 

uniform beds, most of which do not 

exceed 5 feet in thickness; limestone 

beds alternate with thin layers of chert 

or sand; effervesce strongly with acid; 

some beds are very fossiliferous, but 

fossils are poorly preserved. Owing to 

its laminated character this member is 

less resistant to erosion and reced.es 

faster than the overlying heavy-bedded 

limestone, so that in many places it is 

overhung by the overlying member. 

This difference in erosion determines 

the formation of great niches or alcoves 

in the Redwall cliff. Thickness estimated ............................. ±220 

B. 3. Heavy-bedded magnesian limestone; 

chemical composition near that of dolomite (see analysis, p. 55); does not effervesce freely with acid; some beds 

are separated by thin layers of l~osely 

consolidated sandstone; under Wallace Butte the limestone rests on a 

layer of loose gnarly sandstone 1 foot 

thick. Thickness estimated ......... ±80 

[NoTE.-The foregoing section of subdivision B was examined along the Bass 

trail, at locality 6, figure 2. The thickness assigned to subdivision B is the 

thickness of its cliff under Wallace 

Butte in Bass Canyon as measured on 

the topographic map of the Shinumo 

quadrangle.] 

C. Brecciated limestone composed of subangular fragments of limestone 6 inches 

or less in diameter embedded in a 

matrix of yellowish or purpfish sand; 

in places passes into gnarly calcareous 

sandstone or into limestone containing 

irregular masses of yellowish or purplish sand; forms steep slope or weak 

cliff under sheer cliff of subdivision B. 

In places the base oi this curious bed is 

uneven; in places the summit is un-

±500 

even. Average thickness....... . . . . . . 8 

[N OTE.-The foregoing section of subdivision C was measured under Wallace 

Butte on the west side of Bass Canyon, 

at locality 7, figure 2.] 

Temple Butte limestone: 

1. Thinly laminated sandy magnesian lime-

' stone ·in rub.bly beds mottled pale 

purplish or buff; effervesces feebly 

with acid; soft; forms slope. Some 

mottled beds resemble beds in the 

Muav limestone that have been bored 

by worms........................... 10 

2. Limestone like No. 1 but harder and 

more massive; forms small cliff........ 3 

3. Thin beds of limestone like No. 1 alternating with thin beds of intraformational conglomerate composed largely 

of flattened pebbles of limestone; form 

slope................................ 5! 

4. Limestone likeN o. 2; forms cliff ... _..... 4~ 

5. Limestone like No. 1; forms slope .. _. ___ . 21 

6. Limestone like No.2; forms small cliff... 1 

7. LimestonelikeNo.1;formsslope........ 6 

8. Limestone likeN o. 2; forms strong cliff.. 3 

9. Limestone like No.2; forms cliff ........ 1

• 3 
P:ALEOZOIC FORMATIONS OF THE GRAND CANYON. 

10. 

11. 

12. 

13. 

14. 

Massive bed of purplish crystallin~ magnesian limestone; fqrms cliff ......... . . 

Limestone like No. 2; forms cliff; surface 

exhibits cross sections of poorly preserved cup corals(?) .......... _ ..... . 

L~mestone l~ke No. 1; forms sl~pe. ]" ~----

Limestone hke No.2; forms chff ........ . 

Limestone like No. 1 (for analysis see 

p. 52); very soft; forms gentle slope 

above strong cliff at top of und rlying 

Muav limestone .......... · ............ . 

[N OTE.-The foregoing section was measured under Wallace Butte on th~ west 

side of Bass Canyon, at localfty 7, 

figure 2. At this locality th0 contact between bed 14 and the underlying Muav limestone exhiilits no 

irregularity in a distance of 1,000 

feet, and the bed appears to rest conformably upon the Muav lim stone , 

but in Ruby Canyon, 2 miles southeast 

of Bass Canyon, the con tact is very 

uneven, exhibits vertical ineqJalities 

of 40 feE;Jt or more in horizontal distances of a few hundred feet, and 

clearly represents a strong line of 

erosion.] j 

Muav limestone: 

A. 1. Buff hard massive crystalline dolomite in 

heavy beds (for analysis seep.-); does 

not effervesce with acid; forms cliff. 

At one place on the east side _of Bass 

Canyon the thickness of the dololnite 

is 25 feet less than it is under "jallace 

Butte, on the west side of the c~nyon, 

where this section was measured.! Apparently a depression in the surtace of 

erosion at the top of the Muav I exists 

at that point, but the feature is. obscure 

because fans of talus mask the strata 

for some distance on both sides /of the 

exposure ..................... . i .... . 

2. Poorly exposed bed of soft rock, apparently greenish-buff shaly sandstone; 

determines a narrow ledge \vhich 

breaks the cliff formed by Nos. 1 and 3 

3. Buff hard massive crystalline dolomite 

/in heavy beds; probably originally a 

1 

3 

6 

3 

5 

75 

52 

1 

very fine calcareous sand; e"'hibits 

indistinct cross-bedding; _forms jcliff . . __ 1_~ 

B. Pale-buff to greenish-buff fine-grain1d calcareous sandstone blotched purplish 

in places; beds differ greatly in thickness, ranging from a fraction of ah inch 

to 6 feet; some beds are massive;Jothers 

thinly laminated; some exhioit indistinct cross-bedding; massive beds 

predominate in upper part of thb sub63 

c. 1. 

division, thinly laminated beds in 

lower part. The sand is prevailingly 

calcareous; many beds effervesce readily with acid, and specimens of these 

beds tested in the Survey laboratory 

show little magnesium; the rock in a 

few massive beds, howeve1·, resembles 

the overlying dolomite (A 3), effervesces feebly, and is magnesian. 

Some of the sand is finely micaceous, 

and some is finely quartzose. Anumber of the beds contain tiny greenish 

grains of glauconite. Some beds are 

worm-bored. Beds of intraformational 

conglomerate composed of flattened 

pebbles of calcareous sandstone occur 

at several horizons. A thin layer of 

reddish sandy shale associated with a 

bed of intraformational conglomerate, 

40 feet above the base of the subdivision, exhibits well-preserved sun 

cracks. The laminated beds at the 

base of the subdivision consist chiefly 

of platy micaceous sandstone which 

does not effervesce with acid . ........ . 

Thin layers of calc~reous intraformational 

conglomerate, platy greenish micaceous 

sandstone, greenish micaceous shale, 

and buff cross-bedded calcareous sandstone in countless alternations. The 

intraformational conglomerate consists 

essentially of small flattened pebbles of 

gray and buff mottled limestone like 

that of subdivision D and buff calcareous sandstone; all parts of it effervesce 

with acid. The pebbles have rounded 

edges and are cemented together by 

fine-grained calcareous m i c ace o us 

sandy mud or by calcium carbonate. 

Most of the rock contains worm burrows and fucoidal casts filled with buff 

sand. Beds range in thickness from less 

than half an inch to 6 inches and are 

lenticular; many wedge out in distances of 100 feet; some pass horizontally into cross-bedded sandstone; 

small local unconformities are common. 

Some beds are blotched purplish. 

Many1ayers of the micaceous sandstone 

and shale are as thin as card board. 

Much of the calcareous sandstone consists almost entirely of calcium carbonate and might be classed as limestone ,· 

but the cross-bedding reveals its clastic 

origin. In most places bed 1 and the 

underlying beds 2 to 7 form cliffs ..... 

2. Gray and buff mottled limestone like subdivision D, but in beds separated by 

partings of buff sand as thin as cardboard .... . .... _ .................... . 

3. Intraformational conglomerate like that in 

bed 1 . ... -····· · ···········--------

33 

72 

8 

2 
34 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

C. 4. Mottled limestone in thin beds with sandy 

partings. _ .. ___ ........ _ ... _ ... _ . . . 1 

5. Intraformational conglomerate_ . _ . _ . . . . ! 

6. Mottled limestone in thin beds with sandy 

part1ngs I • _ . _ . _ . _ 2 .. _ ..... _ . _ . _ ... _ ... 

7. Intraformational conglomerate .. _ ... _ . . 1 

8. Bedk of intraformational conglomerate 

averaging 6 inches thick alternating 

w;ith thin beds of gray and buff mottled 

limestone; form steep cliff_ . . . . . . . . . . 32 

9. Hard massive bed of intraformational conglomerate; forms small cliff._ .. _..... 1 

10. Bed~ like No.8 but containing numerous 

very thin partings of fine micaceous 

and calcareous buff sandstone near 

base; form slope.- ... -........ · ... -.-. 43 

11. Buff fine-grained crystalline limestone, 

weathering snuff-brown; effervesces 

strongly with acid; exhibits indistinct 

cross-bedding and is probably comppsed of fine calcareous sand; hard; 

forms small conspicuous brown cliff and 

ifl a very persistent bed in the western 

part of the Kaibab division, being 

traceable throughout the Shinumo 

qilladrangle ....... -.-.--- .. -.. -.---- 8 

12. Beds of gray and buff mottled limestone 

and intraformational conglomerate in 

countless alternations; contain many 

thin partings of fine-grained buff or 

greenish-buff micaceous and calcareous 

sand; worm borings and fucoidal casts 

abundant; beds form slope. In general the beds of mottled limestone contain more buff fine sandy material than 

those which constitute the underlying 

subdivision D, although some are comparatively pure. · An analysis of a 

sample from a typical bed of the impure 

mottled limestone 35 feet below the top 

of No.12 in Turquoise Canyon (seep. 43) 

. shows that about a quarter of the rock 

consists of insoluble material, probably 

silica, whereas the remainder con'Sists 

e,ssentially of calcium carbonate with 

only a trace of magnesium. The beds 

o~ intraformational conglomerate effervesce as freely with acid as the mottled 

limestone; tests indicate tpat they are 

not magnesian and that they probably 

differ little in chemical composition 

from the impure mottled limestone.... 142 

D. Gray and buff hard thin-bedded mottled 

limestone; effervesces with acid; forms 

strong cliff. The color of the pure 

limestone is gray to bluish gray, but 

many beds contain a varying amount of 

buff fine calcareous, more or less 

micaceous sand or sandy mud which 

imparts a mottled appearance to the 

rock. The limestone contains numerous fucoidal or coralloid forms, most of 

which are composed of the buff sandy 

material, but some of which are composed of the limestone itself. Probably -

most of these forms are filled worm 

· burrows. At the base of the subdivision thin layers of platy buff sandstone 

and greenish shale alternate with the 

· mottled limestone for about 10 feet. _ . 97 

[NoTE.-The foregoing section of the 

Muav limestone was measured under 

Wallace Butte on the west side of Bass 

Canyon, at locality 7, figure 2.] 

Bright Angel shale: · 

A. Beds of greenish soft micaceous shale in 

paper-thin laminae alternating with 

beds of buff platy hard fine-grained 

micaceous quartzose sandstone which 

range in thickness from a quarter of an 

inch to an inch; worm borings abundant; beds form alcove under cliff of 

subdivision D of Muav limestone..... 10 

2. Alternating thin beds of worm-worked 

buff calcareous sandstone and greenishbuff micaceous sandy shale; form steep 

slope. ________ . . . . . . . . . . . . . . . . . . . . . . . 21 

3. Thin beds of buff sandstone, greenish 

shale, mottled limestone like subdivitri.on D of the Muav, a;nd snuff-brown 

dolomite in countless alternations; 

most beds less than 1 inch thick; worm 

borings abundant; many layers of sandstone ripple-marked; beds form weak 

cliff .•. ___ ................ -.. ·-.. -. . . . 26 

4. Snuff-brown hard crystalline glauconitic 

dolomite forming small cliff. The 

glauconite appears to constitute from 

a quarter to a half of the rock and 

occurs in tiny rounded grains scattered through a groundmass of crystalline dolomite. Although the rock 

is crystalline, weathered surfaces exhibit distinct cross-bedding, showing 

that the rock is of classic origin.----. 1 

---gg 

B. Thin peds of buff platy quartzitic sandstone 

and greenish micaceous shale in countless alternations; glauconite very 

abundant at top; a 4-inch bed of 

magenta sandstone containing groundup remains of linguloid brachiopods 

and much glauconite occurs 7 feet 

above the base; neither sandstone nor 

shale effervesces with acid;' beds form 

slope. The sandstone beds average a 

quarter of an inch in thickness and 

consist chiefly of tiny transparent grains 

of quartz but contain small flakes of 

muscovite and scattered grains of 

glauconite; most beds speckled with 

small reddish or brownish spots; ripple 

marks and worm burrows abundant. 

Much of the shale is in paper-thin 

laminae whose surfaces exhibit a satiny 

luster imparted by innumerable tiny 

·flakes of muscovite; many outcrops are 
PALEOZOIC FORMATIONS OF THE GRAND CANYON •. 35 

covered with a whitish saline efflorescence ... :......................... 17 

B. 2. Magenta to dark-green glauconitic sandrock passing at top into a 6-inch bed of 

snuff-brown glauco:p.itic crystalline 

dolomite; forms weak cliff. In places 

the sandrock and dolomite pass into 

intraformational conglomerate containing broken shells of linguloid 

brachiopods. The dark-green phase of 

the sandrock owes its color to glauconite; the magenta phase owes its color 

to ferritic cement, largely hematite, 

which makes the rock relatively heavy 2! 

3. Buff platy sandstone and greenish shale 

like No. 1; beds form slope.... . . . . . . . . 60 

4. Dark magenta cross-bedded sandstone 

containing much glauconite; forms 

small cliff. . . . . . . . . . . . . . . . . . . . . . . . . . . 1! 

5. Buff platy sandstone and greenish shale 

like No. 1; glauconite very abundant; 

beds form slope...................... 38 

6. Thin beds of snuff-brown to buff finegrained calcareous sandstone forming 

the upper of the two prominent brown 

cliffs in the middle of the Bright 

Angel shale; . thin platy beds of finely 

crystalline buff dolomite containing 

shells of linguloid brachiopods occur 

in the upper 5 feet .............. L • • • • 13 

7 . .:Buff platy sandstone and greenish shale 

iike No. 1; beds form slope and ledge 

between the c,liffs ,of Nos. ~ and ~; 

some thin beds c~nsist alinost wholly 

of glauconite ...... ~ .... .-...... . . . . . . . 38 

8. Heavy beds of snuff-brown massive crystalline dolomite (for analysis seep. 40), 

7 feet; passing down into beds of b~1ff 

fine-grained cross-beddeq. glauc~.mitic , '' I 

sandstone, 5 feet; .the dolomite and 

sandstone form the' lbwer of the two 

brown cliffs · in the middle of the · 

Bright Angel shale ...... ·............. 12 

9. Buff. platy san,qstone and greenish shale 

like No. ,1; a 4-inch bed of fossiliferous magenta glauconitic sandstone 

occurs 34 feet above . the base; beds 

form gi:nitle slope ........ ~ . . . . . . . . . . . . 66 

10. Fossiliferous magenta -glauconitic sandstone,_ 2 feet, passing '!JP into buff 

platy quartzitic sandstone, 2 feet; 

beds form a weak cliff . .'. . . . . . . . . . . . . 4 

11. Huff platy sandstone and greeltish shale 

like No. 1 but containing more platy 

sandstone :ln proportion to the shale, 

so that the beds form a somewhat 

steeper slope. Beds of magenta sandstone containing hematite, glauconite, 

and ground-up shells oflinguloid brachiopods occur at 16, 23, 32, 34, and · 

66 feet above the base; these beds range 

in thickness from 1 to 4 inches; part 

of the hematite occurs as cement 

between the sand grains; part of it 

coats the sand grains in tiny concentric layers, giving the rock an oolitic 

appearance; most of the sand grains 

are quartz or glauconite but some are 

pink feldspar; some of the ferritic beds 

resemble Clinton iron ore.............. 83 

[NoTE.-The foregoing section of the 

Bright Angel shale was measured on the 

east side of Bass Canyon about half a 

mile south of Bedrock Tank, at locality 

8, :figure 2.] 

Tapeats-sandstone: · 

A. White to greenish-white cros~-bedded sandstone in rather thick beds composed 

chiefly of clean quartz sand; contains a 

few lenses of soft greenish sandy shale; 

· lenses of hard sandstone alternate with 

lenses of softer sandstone which ' etch 

out and form alcoves and shelves. 

The sandstone is speckled with small 

magenta or brownish spots which repre333 

sent segregations of ferritic materiaL.. 35 

B. Chocolate-colored sandstone· in rather thin 

beds separated hy layers of greenish or 

brownish shale; contains some crossbedded layers, but evenly bedded 

layers predominate................ . . . . 43 

C. Hard chocolate-colored cross-bedded sandstone; commonly a . pebbly grit composed chiefly of quartz sand; many 

beds are indurated to quartzite; small 

yellow rounded quartz pebbles, the 

largest the size of peas, are a characteristic constituent; thin lenses of shale 

are rather abundant in the upper half 

of the member; the lenses of the shale 

or softer sandstone etch out and form · 

alcoves and shelves. In many places 

the ·lower half of the cliff is incrusted 

with salt (sodium chloride), and in 

some protected situations the salt forms 

stalactites. Lenticular beds of conalome~te from 1 to 15 feet thick occur b . 

throughout the sandstone but are more 

abundant in the basal portion. Some 

conglomerate beds consist of unassorted 

angular fragments of the underlying 

rocks; others consist chiefly of rounded 

pebbles of quartz. In some places 

where the sandstone rests against hills 

of pre-Cambrian rock, beds of coarse 

breccia occur in the sandstone at the 

base of the pre-Cambrian hills; one of 

these beds of breccia exposed in a cliff 

on the north side of Colorado River, 

half a mile southeast of the mouth of 

Bass Canyon, contains blocks of preCambrian quartzite 30 feet in diameter. 

The Tapeats sandstone rests on an 

eroded surface which in some places in 
36 SHORTER CONT'RIBUT'IONS TO GENERAL .GEOLOGY, 192:2. 

the Shinumo quadranale exhibits a relief of nearly 600 feet; ~onsequently the 

thi<;kness of subdivision C at any point 

depends on the topography of the · 

underlying surface. Near the mouth of 

Bass Canyon, where this section was 

measured, subdivision C is 328 feet 

thick, whereas a mile to the northeast. 

under Dox Castle, it is absent. Th~ 

thickness of 250 feet which I have assigned to the subdivision represents 

approximately the average thickness 

in Bass Canyon ... .. ... : ............ ±250 

[N OTE.-The foregoing section of the 

Tapeats sandstone-was measured west 

of the mouth of Bass Canyon, at the 

point where a trail leading from Bedrock Tank to Copper Canyon ascends 

a break in the cliff formed by the 

sandstone, at locality 9, figure 2.] 

Total thickness of Paleozoic 

beds ....................... . ±4014 

THE PALEOZOIC ROCKS. 

CAMBRIAN SYSTEM. 

TONTO GROUP. 

GENERAL FEATURES. 

In the region about Bass Canyon the Tonto. 

group is a series of. conformable strata about 

1,200 feet thick which lies at· the base of the 

Paleozoic and is separated from underlying 

pre-Cambrian rocks and from overlying Devonian and Carboniferous rocks by unconformities of erosion. In lithology the group as a 

w:hol~ exhibits a passage upward from sandstone to limestone, roughly in three stages. 

The strata at the base ·of the group are sandstones; those in the middle portion are chiefly 

fine-grained sandstones and sandy shales; 

and those in the upper portion are more or less 

sandy calcareous rocks which pass at the top · 

into magnesian limestone. These three lithologic stages afford a natural basis for dividing 

the group into formations. Accordingly, in a 

former report describing the region about Bass 

Canyon 7 I proposed a threefold division of the 

Tonto group and used the names Tapeats sandstone, Bright Angel shale, and Muav limestone 

to designate the formations. The name Tapeats sandston3 is applied to the sandstone at 

the base of the group, the name Bright Angel 

shale to the sandstone and shale of the middle 

portion, and the name Muav limestone to the 

7 Noble, L. F., The Shinumo quadrangle, Grand Canyon district. 

Ariz.: U. S. Geol. Survey Bull. &19, p. 61, 1914. ' 

more or less calcareous strata that constitute 

. the upper portion. Walcott had previously 

. adopted a similar threefold division of the 

Tonto. He states, 8 "I find among my notes 

made after the tnp to the Grand Canyon in 

1901 * * * that I had given names to the 

three divisions of the Tonto along the same 

lines that you have, so I can readily agree with 

your present subdivisions and nomenclature." 

At Bass Canyon the three formations are distinct in lithology and in topographic expression, 

but farther southeast, in the region between the 

Hermit and Grand View trails, where most 

visitors see the Grand Canyon, the boundary 

·between the Muav limestone and the Bright 

Angel shale is indefinite, and the two formations do not appear at first sight to differ conspicuously, whereas the Tapeats sandstone and 

the Bright Angel shale preserve their distinctive characters and can be distinguished readily. 

Some uncertainty has therefore existed as to 

the limits of the Muav limestone in the more 

frequented part of the Grand Canyon, and the 

propriety of a threefold division of the Tonto 

·has been questioned. . 

To determine whether the Muav limestone 

as defined at Bass Canyon is actually traceable 

into the region between the Hermit and Grand 

View trails, I have measured six sections of the 

Tonto group at different points in the south 

wall of the Grand Canyon. These sections, 

spaced from 3 to 8 miles apart, carry the lithology of the Tonto· through a distance of about 

28 miles southeastward-from Garnet Canyon, 

3 miles west of Bass Canyon, to Cottonwood 

Creek, in the Grand View region-and, in connection with a section measured by Walcott 

at Nunkoweap Valley, 15 miles north of Cottonwood Creek, carry it practically through the 

Kaibab division of the Grand Canyon. These • 

seven sections are shown on Plate XX. In 

addition to recording the Tonto lithology I 

have represented the unconformity at the summit of the Tonto by indicating diagrammatically the amount of relief which the eroded 

surface exhibits at each locality, and, where the · 

beds that lie between the unconformity and the 

Redwall cliff were accessible, I have recorded 

their character and succession. Owing to lack 

of space in the drawing I have presented only 

a brief description of the lithology of each section. The Bass Canyon section 1s given in 

s Walcott, C. D., personal communication. 
SYSTE M 

CARBONIFEROUS 

DEVONIAN 

z 

<( 

(t 

[) 

~ 

< 

0 

GROUP AND 

FORMATION 

Redwall 

0.. 

:J 

0 

ll: 

l') 

0 

1-

z 

0 

fFEET 

--?--

Massive chocolate 

cross-bedded 

sandstone in 

sheer cit!!; 200'r 

Garnet Canyon--- 3 mt!e-s E.----~ 

Burr calcareous 

sandstone, thin bedded 

olbase 78' 

Bass Canyon ---- 8miles SE.----

ii~~ Th1i1-bedded bu!r /> and purpl1sh mottl .. d 

Sallo/ m11$ne.s/on 

ltine5toneJ 75 ' 

h"tt:;*o:.i~~--,li:-:-;NC0NF0Hfflry-- ~ 

Bu!TmassiV!' ......_ ........._ 

do/omits. 63' ...._ 

Slate Creek--- Sm/les SE.- Hermit Creek --- 5.5 m/les E. -Pipe Creek-----

lhin-hedded mottled limestone, 

,;,tra/Ormelione/ 

con.§lomerate, 

;r:r.:y...,;:q Thin-beddt!d 

mat/led limestone, 

intraiOrmetional 

conalofflt!'raf,, 

calc-artf'ous sandstone, 

and pl41& mic6ceou6 Mmistont!' or shalt}Z41' 

~~~~ colcareous sandstone, and pla(y micaceous , 

sandstone or shale, ?3? 

Croy and buff thin bedd~d 

mottled limestone, tzz' 

MassivCJ choco!Rte cross-bedd.-cl 

sandstone in 

sheer c//1'(, 2so'r 

Gray end burl' 

thm-hedd.-d 

mollled limes/on.-. Conl.!l'ins parlin§sor 

f,'!'?Y .5hale in baSil! 117 /lMt: 

Thin-boddt!'d mottled 

limes/on<'!', /ntrBIOrm1lional 

con,!lomerek, calcareous sandston"'t 

imd micNceous .g,_nish 

shale and p161y sand.lon<', ?01' 

ffNssive <-ho<>olald 

cros8-hHdd«t' 

.sandston~ 

/n sh~<'r chIT, 

175 'I. 

ARCHE:AN 

!tines/on~, 

tidral&rmaltot141 

con§lomO'rale, 

ralca~ous :Jandslone, 

ana' ff.ICQC'~US 

.frl'enish :shalt!' , 

ami platy :>andston~, 189 

COLUMNAR SECTIONS OF THE TONTO GROUP IN THE GRAND CA YON, FROM GARNET CANYON TO COTTONWOOD CREEK 

By L. F. Noble, with a section at Nunkoweap Valley, by C. D. Walcott 

7 miles se. ------

ARCHEAN 

Cottonwood Creek--.r15mtles N.-- Head of 

Nunkoweap 

Va lley 

-

C.D Walcott Tenth Annual Report 

US. Geolo.Rical Survey-; 

11trt I, ltf90, p 584 

3 

Mottled ond Y8ri~,Satt?d 

ca!ctlreoarenacl!!ous 

rocks,3"10' 

..., 

c: 

s 

<J) 

... 

E 

-?--1-------+--l 

4-

Thin-hedded 

sandstone_,, 

325ft. 

I"OSSILS (NEAR BASt): 

--........... ---- ----- ............_ - - UNCONFORMITY 

----- Chuor sholes, etc. 

----- [or A'Jonkian ............_ Gron Csnyon ............_ series} 
PALEOZOIC FO~MATIONS 

detail in the present report (see pp. 26-36), 

but an account of the detailed lithology of the 

other sections is beyond the scope of this 

paper and will be reserved for another report. 

In all six sections the Bright Angel shale and 

. Muav limestone were measured by hand level . 

and the Tapeats sandstone .was measured by 

aneroid barometer except at Bass Canyon, 

where the level was used. The sections at 

Garnet Canyon, Bass Canyon, Slate Creek, and 

Hermit Creek are beli~ved to be more accurate 

than those at Pipe and Cottonwood creeks because they were checked over in detail during 

a subsequent field trip, whereas the sections at 

Pipe and Cottonwood creeks were not reviewed. 

These sections show that the Muav limestone 

as defined at Bass Canyon is represented by 

equivalent beds throughout the Kaibab division, and that the principal subdivisions of th~ 

Bass Canyon section preserve enough of thet 

original character to be recognizable in thr 

other localities, although large parts of thr 

formation become sandy southeast of Bass 

Canyon, the · proportion of sandstone to lime'-

stone increasing southeastward. _The appea+ 

ance of sandy m~terial in the lower part of thf 

Muav sout~east of Bass Canyon makes it i~~­

creasingly difficult t? define exac~ly the bou~ 

dary between the Bright Angel shale and the 

!f,~:,:imestone in that direction, as will br 

When I proposed the ·name Muav limestonf 

I used the term "limestone" because in -the 

type locality, near Bass Canyon, the formatio~ 

as a whole contains more limestone than sand~ 

stone and shale. Inasmuch as the f'o_rmatiof 

becomes increasingly. sandy southeast of Bass 

Canyon it may be advisable eventually t0 

change the name to Muav formation,- but i~ 

seems best to retain the name Muav limestonf 

for the present, until the formation has beem 

studied over a wider area than that covered i1

1 

this report. 

TAPEATS SANDSTONE. 

Oharacter.-The Tapeats sandstone is essen-~ 

tially a medium to rather coarse sandstone, 

grading here and there into a pebbly grit an<ft 

including beds of conglomerate and shale1 

The prevailing color is chocolate-brown, al 

though many beds are buff or greenish buff an j 

OF THE GRA~D CANYON. 3 7 

some beds a e pale greenish white. The conglomerate ~o ms.lenticular be~s that may occur· 

at any horirn·Inthe formatiOn but are more 

abundant n ar the base, where as a rule the 

conglomerat is arkosic and consists of poorly 

assorted fra~ments of underlying rocks. Some 

of the congl merate, however, ~swell assorted 

and consist of- rounded pebbles of quartz. 

Most of th~ shale occurs above the middle of 

the formatio in thin lenses between layers of 

sandstone. In general the component materials of the ormation be~ome finer and better 

assorted tow rd the top. ,The uppermost beds 

at Bass Ca~yon are clean white or greenishwhite cross- edded sandstone. 

Among th distinctive features of the forma- -

tion are har ness, which causes it to weather · 

into sheer liffs, prevaili:qg chocolate color, 

cross-beddin , _and a rather coarse horizqntal 

banding du to the fact that the peds form 

elongated ho izontallenses and differ in texture 

and hardnes . Here and there beds .of shale 

alternate wi h beds of sandstone, and at most 

places the s ndstone itself, although prevailingly hard, 1

xhibits wide differences in induration. A beq . of sandstone which in one place 

is cemented! into compact vitreous quartzite 

may be poorly consolidated a few hundred feet 

away. Vert' cally beds of hard quartzitic sandstone succee 1 beds of softer sandstone in countless alternat ons. Erosion etches the bands of 

softer mater\al into long low alcoves overhung 

by 1shelves of harder rock. These shelves and. 

alc0ves apperr on every outcrop of the Tapea-ts 

sandstone a~q are particularly conspicuous in 

its great eli , which is furrowed by tier upon 

tier of them. (See Pl. XXI, A.) One who is 

traveling through the canyon along the Tonto 

platform, or "lower plateau," soon learns to 

appreciate the shelter which these ~'Tonto 

shelves" affbrd and usually selects them for 

his lcamp. Tndeed, the selection is almost compulsory, for lin most tributary canyons water 

comes to the surface in the dry watercourses 

only at the point whe.re the stream channel 

crosses the summit of the Tapeats sandstone. 

Another distinctive feature of the sandstone 

is the occud·ence in many beds of numerou~ 

small yellowjrol.!nded quartz pebbles, the larg-· 

est I of which are the size of peas. Worm mark- · 

ings are common in the white· sandstone at the 

.I 
38 . SHORTER CQ_;NTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

top of the Tapeats and occur here and there in 

the underlying chocolate-colored beds. I have 

observed ripple marks at a few places in the 

formation and sun cracks at one place. Glauconite occurs sparingly in scattered grains in 

some beds. 

In many places in the Kaibab division the 

Tapeats cliff is incrusted with salt. Commonly 

the deposits are less than an inch thick, but 

some of them may cover hundreds of square 

feet. A sample from one of these salt deposits 

in Garnet Canyon was tested in the laboratory 

of the Survey and is reported to consist essentially of sodium chloride. A spring that issues 

from the contact between the Tapeats sandstone and the underlying crystalline rocks at 

a point about half a mile west of Garnet Canyon 

yields a heavy brine. Other brine springs 

issue from this contact at several places in the 

Kaibab division. The water of the intermittent stream in Garnet Canyon is potable above 

the middle of the Tapeats sandstone, but below 

the middle of the sandstone it is too salty to 

drink. These occurrences indicate that the 

Tapeats sandstone contains' salt, although no 

beds of salt have been found within the sandstone. Perhaps a small amount of salt is 

widely distributed in the sandstone but has 

escaped observation because it is not concen-

. trated in beds. Inasmuch as the Tapeats is a 

marine deposit the salt is probably an original . 

constituent of the sandstone. 

The Tapeats sandstone exhibits 'little variation from place to place in lithology or in general appearance and is readily identifiable in 

all parts of the Kaibab di~ision. . 

Stratigraphic relations.-Both base and summit are well defined, the base by a great 

angular unconformity that truncates underlying pre-Cambrian rock~ and the summit by 

a rather abrupt change from coarsely banded 

white cross-bedded sandstone at the top of 

the Tapeats to thinly laminated even-bedded 

sandstone and sandy shale at the base of the 

overlying Bright Angel shale. 

Subdivisions.-At Bass Canyon the formation is rudely divisibl~ into three parts. (See 

Pl. XX.) Subdivision A, at the top of the 

formation, consists of white cross-bedded 

· sandstone which includes a few layers of 

greenish shale. Subdivision B, beneath A, 

consists of evenly bedded chocolate-colored 

sandstone with partings of shale. Subdivision C, at the base, consists of chocolatecolored cross-beqded sandstone and c~mstitutes 

by far the greater part of the formation. As 

the Tapeats sandstone is traced southeastward 

from Bass Canyon, subdivision A decreases 

in thickness and becomes more and more 

like C in lithologic character until it is practically indistinguishabre from C, so that in the 

three easternmost sections shown on Plate 

XX the formation is divisible into only two 

parts and consists essentially of chocolatecolored cross-bedded sandstone capped by 

white cross-bedded sandstone. Where hills 

of pre-Cambrian rock project into the Tapeats 

sandstone, beds of coarse conglomerate may 

appear at any horizon in the sandstone where 

it rests against their steeper slopes, but these 

conglomerates are local in extent and do not 

persist many hundreds of feet. 

Thickness.-The Tapeats sandstone varies 

irregularly in thickness from place to place, 

but the variations have no ultimate stratigraphic significance because the sandstone 

was deposited upon a surface which, although 

remarkably even when considered in relation 

to its vast horizontal extent, is uneven in detail, exhibiting at some places a relief of 600 

· feet. Thus at the point where the section at 

Bas~ Canyon was measured the. sandstone 

attains a thickness of 328 feet, whereas the 

average thickness in Bass Canyon does not 

exceed 250 feet; and a mile away, on the,north 

side of Colorado River, where a hill of hard 

pre-Cambrian strata rises several hundred 

feet above the general level of the pre-Cambrian 

surface, the sandstone was not deposited. The 

thickness assigned to the sandstone at Bass 

Canyon is exceptional. Perhaps 200 feet 

would be a fair estimate of the average maximum thickness in the Kaibab division. 

Fossils.-N o fossils have been fo"!lnd in the 

Tapeats sandstone except near the top. Schuchert9 has noted fragments of an obolid shell in 

the white cross-bedded sandstone at the top of 

the formation near Hermit Creek. Walcott 10 

reports the following fauna "in ·the Tapeats 

sandstone about 300 feet above its base at the 

head of N unkoweap Valley'' : 

9 Schuchert, Charles, The Cambrian of the Grand Canyon of Arizona: 

Am. Jour. Sci., 4th ser., vol. 45, p. 365, 1918. 

10 Walcott, C. D., Cambrian geology and paleontology: Smithsonian 

Misc. Coli., vol. 64, No. 5, pp. 373, 374, 1916. · 
PALEOZOIC FOR.MATIO~S OF·. 'l'HE .GRAND CANYON. . 39 

Dolichometopus tontoensis. 

Micromitra pealei. 

Micromitra (Baterina) crenistria. 

Micromitra (Paterina) superba. 

Micromitra Ciphidella) pannula. 

Obolus zetus. 

Obolus (Westonia) chuarensis. 

Obolus (Westonia) englyphus. 

Lingulella lineolata. 

Lingulella perattenua.ta. 

Billingsella obscura. 

Alokistocare althea. I 

According to Walcott the thickness of th~ 

Tapeats sandstone at Nunkoweap Valley is 300 

feet (see Pl. XX), so that the beds from wHich 

he obtained this fauna must lie at the very top 

of the formation. The age . of the fauna is 

stated to be Middle Cambrian. Practically all 

the forms listed occur also in the Bright Angel 

. shale. 

· The age of the summit beds of the Tapeats 

sandstone is therefore Middle Cambrian. Inasmuch as the formation appears to have been 

deposited continuously, as is indicated by its 

homogeneous character, and · to have accumulated rapidly, as is indicated by' its relatively 

coarse cross-bedded structure, it is not likely 

that any part of it is older than Middle Cambrian. 

BRIGHT ANGEL SHALE. 

Oharacter.-The chief constituent of the 

Bright Angel shale is fine-grained quartzose micaceous sand, which forms innumerable platy 

beds mostly less than a quarter of an inch thick. 

Many _beds of sandstone are separated by partings of. micaceous sandy shale, and at some 

horizons the sandstone and shale are associated 

with dolomitic limestone or with cross-bedded 

. glauconitic sandstone. 

The distinctive features of the formation are 

thin: platy lamination, a prevailingly dull 

greenish-buff color, the occurrence of glauconite 

in many beds, and the abundance of worm-

:markings and fucoidal casts. Many beds are 

ripple-marked. Shells of obolid or linguloid 

brachiopods are abundant at many horizons, 

and most of the shells are broken and worn, 

showing marks of grinding and attrition. The 

ripple marks indicate that the strata were deposited in shallow water, and the broken shells 

indicate that the deposits were subj-ected to 

repeated pounding by waves. . · 

The formation as a whole is the least resistant to erosion of all the formations in the canyon wall. It makes a more or less continuous 

slope, which at most places has retreated far· 

ack from the summit of the Tapeats cliff, 

eaving the so-called ''lower plateau,'' or Tonto 

latform. It owes its weakness to the alternaions of shale and sandstone and to the thin 

. platy lamination of the. beds . . . Actually most 

r

of the platy sandstone 1s wel.l mdurated, and 

orne of it is as compact as quartzite. 

Glauconite is decidedly more abundant in 

he Bright Angel shale than in the other two 

formations of the Tonto group. It occurs 

rather sparingly in most beds in tiny grains 

scattered through the rock but is widely qis-

. tributed in the formation, both vertically and 

horizontally. Apparently no beds consist entirely of glauconite, but an examination of the 

formation anywhere in the Kaibab division of 

the Grand Canyon.will disclose a few beds several inches thick in which nearly half of the 

rock is glauconite and many beds in which the 

grains are sufficiently abundant to impart a 

greenish tinge to the rock. The mineral is not 

confined to the prevailing platy sandstone and 

shale but occurs .. in the dolomite, intraformational conglomerate, and cross-bedded sandstone described below. An interesting feature 

of its occurrence is its association w:ith deposits 

that were obviously laid down in shallow water. 

Interbedded with the platy sandstone and 

shale ·are two types of rock which, although 

they form only a subordinate part of the Bright 

Angel shale, are particul_arly characteristic of 

the formation. 

One of these rocks is a compact crystalline 

limestone whose color is deep snuff-brown on 

weathered surfaces and pale tan on freshly 

broken surfac~s. Beds ·of this limestone are 

very resistant to erosion and make cliffs. In 

the region about Bass Canyon two beds vertically 35 feet apart appear in the Bright Angel 

shale at a horizon about 125 feet · above its 

base and make two conspicuous brown · cliffs 

in the slope above the Tonto platform. Each 

cliff is about 12 feet high. The beds of snuff.:. 

brown limestone, which determine the cliffs, 

range in thickness from a few inches to 8 feet 

and are associated with beds of green, magenta, 

and brown cross-bedded sandstone. The cliffs 

· are sharply defined and are wonderfully persistent. (See Pl. XXI, B.) Wherever possible 

. the Tonto trail in this part of the canyon follows 
40 SHORTER CONTRIBUT'IONS TO GENERAL GEOLOGY, 1922. 

the narrow ledge at the top of one or the other of 

these cliffs, because the ledges afford much 

smoother going than the dissected and debriscovered slopes of the Tonto platform below. 

Other beds of snuff-brown· limestone appear in 

the Bright Angel shale between the twin cliffs 

just described and the base of the Mua v limestone, but at Bass Canyon they are thin and do 

not make conspicuous cliffs. Most of them are 

associated with beds of greenish and magenta · 

cross-bedded sandstone. 

The snuff-brown limestone effervesces weakly 

with acid. Some beds contain no visible impurities, but others contarn scattered grains of 

glauconite and tiny rounded grains of quartz 

and exhibit cross-bedding. Many beds qontain 

broken shells of brachiopods. In places the 

limestone passes laterally into an intraformational conglomerate co.mposed chiefly of 

rounded, flattened fragments of limestone but 

containing glauconite, quartz sand, and broken 

shells. 

The following analysis of a specimen of the 

snuff-brown limestone forming the lower of the 

·twin cliffs at Bass Canyon (seep. 35) probably 

represents approximately the composition of · 

the purer limes tone. The bed from which the 

specimen was taken contains no visible glauconite or quartz and appears to consist entirely 

of coarsely crystalline limestone. 

Partial chemical analysis of snuff-colored limestone from 

Bright Angel shale. 

[Alfred A. Chambers, analyst.] 

Insoluble ..................... : ....... ' 2. 66 

(Al, Fe)20 3 ........................... 5. 44 

CaO .................... : ...... -...... . 29. 54 

MgO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18. 26 

From this analysis it appears that the rock 

is an impure dolomite. The presence of quartz 

grains in beds closely associated with the one 

analyzed suggests that the insoluble impurities are largely quartz sand, and the fact that 

the rock weathers brown suggests that the 

other impurities are largely iron. Inasmuch as 

the snuff-colored limestones effervesce weakly 

\vith acid and differ from one another chiefly 

in the amount of impurities that they contain 

I have called them all dolomites in this report. 

Another characteristic rock in the Bright 

Angel shale is dark~green or magenta crossbedded sandstone. Most of this sandstone 

forms rather massive beds, which range in 

thickness from a few inc,hes to several feet. 

The component grains are rather coarse and 

in most beds are loosely cemented, so that the 

rock crumbles easily. Some beds, however, 

form weak cliffs. The chief constituent of the 

sandstone is quartz, but many beds contain 

glauconite and many contain a large amount 

of ferritic sandy mud and more or less hematite. Broken shells of brachiopods are abundant in some beds. These green and magenta 

sandstones are readily distinguishable from the 

prevail~g platy sandstone by. their deep colors, 

cross-bedding, absence of thin lamination, and 

relatively coarse text.ure. The colors of some 

beds are very striking, green shading into deep 

bottle-green and magenta into deep purplish. 

brown. In places these colors are mingled in 

blotches in the same bed, producing a curious 

mottled effect. The greenish beds owe. their 

color largely to glauconite, and the magenta. 

beds owe theirs to ferritic material. Some beds 

associated with snuff-colored dolomite weatherbrown. 

At Bass Canyon the thickness of the Bright 

Angel shale is 391 feet and I have divided it into two members-subdivision A, at the top, 58 

feet thick, and subdivision B, below, 333 feet 

thick. Both subdivisions consist essentially 

of thin-bedded greenish and buff micaceous 

shale and .sandstone, with which snuff-brown 

dolomite and greenish and magenta sandstone · 

.of the types just described are interbedded at 

irregular intervals. The character and succession of the beds are recorded in the columnar 

section (pp. 34-35). In general composition 

subdivision A differs from B only in that it contains, near the base, a few · beds of mottled 

limestone similar to those which constitute 

subdivision D of the overlying Muav limestone. 

In a former report 11 I included subdivision A 

in the Mu11v limestone, placing the base of the, 

Muav at the lowest point where mottled limestone appears in the Tonto group, but in the 

present report I have included subdivision A 

in the Bright Angel shale, which as here de-· 

fined includes all strata between the white 

cross-bedded sandstone at the top of the Tapeats and the cliff-making gray and buff mottled limestone that constitutes subdivision D 

of the Mua v. This definition is in accord with. 

Walcott's observations at Kanab Creek. Waln Noble, L. F., op. cit., p. 65. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 131 PLATE XXI 

A. TYPICAL EXPOSUR~ OF TAPEATS SANDSTONE ON COLORADO RIVER OPPOSITE MOUTH OF 

ELVES CHASM, SHINUMO QUADRANGLE, ARIZ. 

a, Muav limestone; b, Bright Angel shale; c, twin cliffs of snuff-colored dolomite of Bright Angel shale; d, Tapeats sandstone; e, Vishnu schist. 

B. TYPICAL EXPOSURE OF BRIGHT ANGEL SHALE, MUAV LIMESTONE, TEMPLE BUTTE LIMESTONE, REDWALL LIMESTONE, AND SUPAI FORMATION IN NORTH WALL OF GRAND CANYON 

OPPOSITE GARNET CANYON, SHINUMO QUADRANGLE, ARIZ. 

a, b, c, Supai formation, subdivisions A, B, C; d, Redwall limestone; e, Temple Butte limestone; J, Muav limestone; g, Bright Angel shale; h, twin cliffs of snuff-colored dolomite in Bright Angel shale; i, Tapeats sandstone. 

PALEOZOIC FORMATIONS OF THE ,GRAND CANYON. 41 

cott's section at Kanab Creek (see Pl. XX) 

shows 100 feet of greenish micaceous shale and 

sandstone (d) beneath beds of mottled limestone (c) that are evidently equivalent to subdivision D of the Muav limestone of my Bass 

Canyon section. He states 12 that a mile or two 

east of Kanab Creek, where more of the greenjsh micaceous shale and sandstone (d) is exposed, the shale and sandstone pass downward 

jnto mbttled gray limestone, calcareous and 

micaceous shale, and dark indurated sandstone. Probably this mottled gray limestone 

is equivalent to the mottled limestone · that 

appears in thin beds at the base of subdivision 

A of the Bright Angel shale in my Bass Canyon 

section, so that subdivision d of Walcott's section at Kanab Creek is roughly equivalent to 

my subdivision A at Bass Canyon. Walcott 

' states 13 : "I find on my locality label 75 that 

the thin-bedded sandstone and shale (d) ' at 

Kanab Creek is plac8d in the Bright Angel 

shale and the overlying mottled limestone· (c) 

in the Muav limestone." , 

The columnar sections of the Tonto group 

shown on Plate XX trace the lithology of the 

Bright Angel shale through the greater part of 

the Kaibab division. They show that although 

the formation exhibits little change in general 

composition from place to place the interbedded 

layers of green and magenta sandstone and 

snuff-colored dolomite increase in number and 

become thinner and more widely distributed 

through the prevailing platy sandstone and 

shale toward the southeast. This ·change is 

shown clearly in the profiles · of the different 

sections. Thus, at Garnet and Bass canyons 

the formation contains only two prominent 

sets of beds of green and magenta sandstone 

and snuff-brown dolomite, so that only two 

cliffs break the long slope formed by th'e platy 

beds. But southeast of Bass Canyon, at Slate, 

Hermit, and Pipe creeks, two other sets of beds 

of sandstone and dolomite ha~e appeared above 

the lower pair, so that the slope is broken by 

four cliffs instead of two. These four cliffs are 

strongly defined at Slate Creek, fail-ly well 

defined at Hermit Creek, and poorly dJfined at 

Pipe Creek because the beds become] thinner 

toward the southeast. Southeast of Pipe 

Creek, at Cottonwood Creek, these beds are so 

widely distributed in the platy sansls one a~d 

12 Walcott, C. ·D., unpublished notes. 

1a Persona1 communication. 

shale and are all so thin that no bed or set of 

beds·makes a prominent cliff. Here the whole 

formation presents a continuous slope. Three 

miles east of Cottonwood Creek, at "Congress 

Canyon" (Red Canyon), that part of Frech's 

section of the Tonto group 14 which represents 

the Bright Angel shale is similar in lithology 

to my section of the Bright Angel shale at 

Cottonwood Creek. 

Southeast of Bass Canyon beds of green and 

magenta sandstone are more abundant in the 

Bright Angel shale than beds of snuff-colored 

dolomite. In the region between Slate and 

Pipe creeks these sandstones have attracted 

attention as a possible source of platinum and 

.at one time were extensively prospected. No 

samples of the rock examined by the Survey 

have yielded platinum, but some of the ·rock ' 

when crushed and panned yields a small 

amount of magnetite. At Slate Creek some of 

these sandstones, near the base of the Bright 

Angel shale, contain considerable hematite and 

form thin beds that are conspicuous by their 

bright-red color. Between Bass Canyon and 

Garnet Canyon some ferritic beds at this 

horizon exhibit oolitic structure. (See p. 35.) 

Probably the beds of snuff-brown dolomite 

and sandstone that make the twin cliffs at Bass 

and Garnet canyons are traceable far west of 

the area covered by the present report, because 

a section of the Bright Angel shale at the 

mouth of the Grand Canyon 15 shows a double 

cliff of snuff-colored sandstone that is said to 

be continuous throughout the Shivwits division, Gilbert having traced it from the Grand 

Wash to Diamond Creek. 

Southeastward from Bass Canyon the thin 

beds of mottled lin1estone at the base of subdivision A gradually give way to calcareou.s 

sandy sha~e and finally disappea~ southeast of 

Hermit Creek. 

Few hills of pre-Cambria11 rock rise far into 

the Bright Angel shale, but one hill on the north 

side of Colorado River about 3 miles east of 

Bass Canyon rises nearly to the top of subdivision B. So far as known, this is the 

highest hill of pre-Cambrian rock in the Grand 

Canyon. 

Thickness.-The thickness of the Bright 

Angel shale decreases gradually from northwest 

14 Frech, F., Cong. geol. inwrnat., 5• sess., Compte rendu, p. 479. 

15 U.S. Geog. and Geol. Surveys W. 100thM:er.Rept., vol. 3, p. 199, 

figs. 86, 87, 1875. 
42 . SHORTER CONTRJBUTIONS TO GENERAL GEOLOGY; 1922. 

to southeast. Thus the formation is 402 feet 

thick at Garnet Canyon, 391 feet at Bass Canyon, 392 feet at Slate Creek, 344 feet at Hermit 

Creek, 325 feet at Pipe Creek, and 334 feet_ 

(estimated) at Cottonwood Creek. At Nunkoweap Valley, 15 miles north of Cottonwood 

Creek, it is 325 feet thick. ·The beds equivalent 

to subdivision A of the Bass Canyon section 

decrease from 60 feet at Garnet Canyon to 42 

feet at Pipe Creek, and the beds equivalent to 

subdivision B decrease from 342 feet at Garnet 

Canyon to 283 feet at Pipe Creek. At Cottonwood Creek the two subdivisions can not be 

separated with certainty. 

FossiZs.-Fossils are abundant at several 

horizons in subdivision B of the Bright Angel 

shale. The following species listed in my report 

on the geology of the Shinumo quadrangle 16 

were collected by Walcott or by me at several 

horizons in subdivision B in the region about 

Bass Canyon and Shinumo Creek: 

Lingulepis spatulus. 

Lingulella acutangula. 

Lingulella lineolata. 

Lingulella perattenuata. 

Obolus (Westonia) themis. 

Indiana faba. 

At 25 feet above the base of subdivision B in 

Serpentine Canyon I have collected and Edwin 

Kirk has identified Micromitra (Paterina ) 

superba and Lingulella lineolata, and at 165 feet 

above the base of subdivision B near Hermit 

Creek Obolus ( Westonia) chuarensis and Mieramitra (lphidella) pannula. 

At 100 to 120 feet above the base of subdivision B near the Bright Angel (Cameron) trail 

Walcott 17 has collected the following species: 

Obolus (Westonia) chuarensis. 

Eocystites? undet. sp. 

Hyolithes. 

Alokistocare althea. 

Dolichometopus productus. 

Dolichometopus tontoensis. 

The age of this fauna is stated by Walcott 

to· be Middle Cambrian. 

In 1915 Schuchert studied the Bright Angel 

shale at Hermit Creek and collected fossils at 

several horizons. He states 18 : 

When the sandy muds were forming, seaweeds (Palaeophycus) were common, along with a great abundance of 

burrowing annelids. Trailings and fucoidal casts are 

I& Noble, L. F., op. cit., p. 64. 

17 Walcott, C. D., Cambrian geology and paleontology: Smithsonian 

Misc. Coil., vol. 64, No.5, p. 374, 1916. 

Is Schuchert. C:!:!.arles, op. cit., p. 367. 

nearly always to be seen, and also the vertical burrowings 

of worms like Arenicolites. * * * In spite of the fact 

that almost no good fossils are to be had in the Bright 

Angel formation, yet the physical phenomena show that 

the epeiric sea of this time must have been rich in life. 

This is proved by the abundance of fucoidal casts, trailings, 

and annelid burrows. Further, in some of the sandstones 

obolid fragments teem, and at times their shells make up 

one-third of a stratum. When the obolid shells are prevalent, glauconite is also common, and the formation of this 

mineral is probably onditioned by the decomposition 

of the organic remains. On the other hand, there are 

entire beds of glauconite up to a few inches thick that are 

almost devoid of fo8sils. When glauconite is very abundant, there are also apt to be thin beds and even zones a 

few feet thick qf low-grade iron ore. 

Palaeophy(JUS casts are very common and well preserved 

at 15 feet above the Tapeats sandstone, and 150 feet 

higher is a glauconitic sandstone replete with the brachiopods Micromitra (Iphidella) pannula (White) and Obolus 

(Westonia) chuarensis. Ten feet higher occur abundantly 

in thin-bedded sandstones Obolus zetus and rarely Obolus 

( Westonia) themis and Lingulella acutangula. 

The most prominent horizon for fossils, consisting 

almost entirely of obolids, is the one just mentioned, 

which occurs from 150 to 170 feet above the base of the 

Bright Angel formation and is at the same time a general 

level for thin-bedded sandstones. 

It is evident that tP,e age of at least the 

lower 170 feet . of subdivision B of the Bright. 

Angel shale is Middle Cambrian, as shown by 

fossils. I have found no determinable fossils 

in the upper part of the subdivision but have 

noted in a bed near the top small fragments of 

obolid shells similar to those that occur in the 

lower 170 feet. I have found no fossils in 

subdivision A at Bass Canyon, nor in beds 

that occupy the equivalent horizon at localities 

where I measured the other Tonto sections. 

But inasmuch as subdivision A differs in 

general' lithologic character from subdivision 

B only in that it contains a few layers of mottled limestone, which gradually disappear east 

of Bass Canyon, and is evidently equivalent to 

a set of beds at Kanab Creek in which Walcott 

has found Middle Cambrian fossils and which 

he includes in the Bright Angel shale (seep. 41), 

I believe the entire Bright Angel shale as defined in this report is }¥fiddle Cambrian. 

MUAV LIMESTONE. 

Oharacter.-At Bass Canyon the Muav limestone consists chiefly of impure limestone and 

calcareous sandstone but includes much platy 

sandstone and shale that do not differ from 

those which occur throughout the Bright Angel 

shale. Platy or shaly lamination is a prominent 

feature except at the top of the formation, but 
PALEOZOIC FORMATIONS OF THE GRAND 0ANYON . . 43 

unlike the Bright Angel shale the Muav, as a brari.ching corals but which Schuchert and Walwhole, is fairly resistant to erosion and makes cott have shown to . be largely the work of 

cliffs or steep slopes. The prevailing roc~ is a worms, ate one of the distinctive features of the 

peculiar gray and buff mottled lime~tone, which mottled limestone . .. Schuchert 19 states: 

o~curs in countless beds averaging-less than an Where the calcareous materials become more dominant 

inch thick. The lower two-thirds of the for:ma- the beds are completely riddled with vertical and anastion consists largely of this mottled limeston.e tomosing worm burrows. These are usually filled with a 

and partly of platy sandstone and shale; the very fine sand, and it is this feature that gives so much of 

upper third consists of calcareous sandstone the Muav its mottled appearance and that led Gilbert 

many years ago to call the formation in the western part of 

overlain by massive magnesian limestone. the Grand Canyon the "mottled limestone." Throughout 

Subdivisions.-At Bass Canyon four subdi- the middle third of the Muav many of the shaly limestones 

visions with persistent features can be differen- are intraformational conglomerates with the pebbles small, 

tiated, although the boundaries between them flat, and more or less rounded on the edges. It is an 

h Th · . 1

. interesting shallow-water, near-shore marine deposit. are not s arp. e massive magnesian 1m_ e- . This is shown in the great abundance of annelid burrows, 

stone at the top of the Muav constitutes sub- in the intraformational conglomerates, and in the variable 

. division A, 63 feet thick, and forms a tltrong nature of the calcareous deposits. * * * The writer 

cliff. The underlying calcareous sandstone has ~ot seen a Paleozoic marine deposit more bored into 

constitutes subdivision B, 72 feet. This sand- .and consumed by mud eaters than this one, and these 

stone, massive at the top but thin-bedded at the burrows are n1ost prevalent in the calcareous zones. Worm . castings are often well preserved in the thin-bedded shale 

base, make$ . a set of weak cliffs that in most zones and occur as little confused heaps or in circular 

places unite with the cliff formed by the over- sausage-like strings, • 

lying limestone. Beneath subdivision B is 24:1 . 

feet of thin-bedded mottled limesto:O:e containing many interbedded layers of platy sandstone 

and shale. These alternating beds constitute 

subdivision C and form a steep ~lope. Beneath 

them is a cliff-making bed of relatively pure 

Most beds of the mottled limestone effervesce 

freely with acid. An analysis of a. typical 

specimen from a bed that exhibits the usual 

mixture of gray limest-one and buff sandy material is given below; 

mottled limestone 97 feet thick, which consti- Partial chemical analysis of mottled, limestone from Muav 

tutes subdivision D, at the base ·of the Muav. limestone. 

In appearance the mott1~d limestone of the 

Muav is unlike any other rock in .the Pale~zoic 

section. Characteristically it is a hard thinbedded impure limestone, whose outcrops when 

seen from a distance_resemhle outcrops of shale. 

The beds range in thickness from less than an 

eighth of an inch to several inches but commonly do not exceed half an inch. The p~rer 

limestone is gray, but most of the rock contains 

a considerable amount of buff material which 

was originally a fine-grained micaceous sandy 

mud. Some o_f this material forms shaly partings between the beds of limestone, and some· 

· of it i.s mixed with the limestone, so that. in most 

beds the gray and buff colors . afe mingled. 

Many limestone beds are intraformational conglomerates composed of small flattened rounded , 

pebbles of mottled limestone embedded in a 

matrix which in some places consists of crystalline limestone and in others of buff calcareous 

material. Nearly every bed of limestone or 

conglomerate exhibits numerous coralloid or 

fucoidal markings. These markings, which · 

Newberry and other early obs~rvers ascribed to 

[Albert A. Chambers, analyst.] 

Insoluble ........................... 23.46 

(Al, Fe) 20 3 •••••• · • ••••••••• : •••••••••• 2.54 

CaO ..... ~ ..................... _·_ ~ ... 48. 25 

MgO .. . _ ....... J . • • • . • • • • • • • • • • • • • Trace. 

This analysis shows that the li~estone is not 

magnesian and indicates that the sandy impurities constitute about a quarter of the rock. 

Subdivision D, at the base of the Muav, consists almost wholly of the thin-bedded mottled 

limestone just described and contains very 

little limestone of the intraformationalconglomerate type. In the basallO feet of the 

subd!vision thin layers of fine-grained platy 

sandstone are interbedded with the limestone. 

These alternating beds define .the lower limit of 

the Muav limestone, and therr separation from 

the underlying greenish shale and platy sandstone of the Bright Angel shale is distinct at 

Bass Canyon, although they represent a transition in lithology rather than an abrupt change. 

Owing to the hardness of the mottled limestone 

subdivision D forms a strong cliff, a feature 

19 Schuchert, Charles, op. cit., pp. 368, 369. 
44 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

which at once distinguishes it from the overlying subdivision C and from the underlying 

Bright Angel shale, which forms slopes. Just 

beneath the cliff are the soft underlying greenish shah~ and sandstone, which persist over a 

considerable area east and west of Bass Canyon 

and etch out everywhere, leaving a small alcove 

overhung by the cliff. The alcove will guide 

the observer to the contact between the Bright 

Angel shale and the Muav limestone. 

Subdivision C consists chiefly of thin-bedded 

mottled limestone but unlike subdivision D 

contains many thin interbedded layers of sandstone and shale. The character and succession 

of the strata, which a,re variable in composition and occur in countless alternations, are 

shown in the detailed section on pages 33-34. 

Some parts of the subdivision contain as much 

sandstone and shale as mottled limestone, but 

other parts contain considerably more mottled 

limestone than any other rock, and large parts 

consist almost entirely of mottled limestone. 

The mottled limestone in subdivision C, 

unlike that in the underlying subd.ivision, is 

chiefly of the· intraformational-conglomerate 

type. In general the beds contain more 

worm markings than those of subdivision D 

and vary more in thickness and composition. 

Some beds attain a thickness of a foot or more, 

and many are from 4 to 6 inches thick, although 

most are less than 1 inch. The thicker beds 

of intraformational conglomerate are lenticular, 

exhibiting considerable variation within horizontal distances of a few hundr~d feet. . Glauconite occurs sparingly in some strata. Most 

of the interbedded sandstone and shale resemble those which prevail in the Bright Angel 

shale. The sandstone is fine grained, quartzose, 

and micaceous and occurs in thin platy layers; 

the shale is greenish, soft, micaceous, and 

sandy. Some of the sandstone, however, is 

calcareous and resembles that which occurs 

in the overlying subdivision B. A prominent 

bed of hard brownish-buff cross-bedded calcareous sandstone 8 feet thick appears at a · 

horizon 142 feet above the base of subdivision C 

and makes a small conspicuous and persjstent 

brown cliff that is traceable over many miles 

in the region about Bass Canyon. Other beds 

of calcareous sandstone are interbedded with 

intraformational conglomerate and platy 

quartzose sandstone at the top of the subdivision. Some of these · upper beds exhibit 

purplish spots and mottlings similar to those 

which appear in the rocks of subdivision B, 

and some of the intraformational conglomerates 

are purplish. 

Subdivision B consists chiefly of fine-grained 

calcareous sandstone but includes beds of 

platy quartzose sandstone, sandy micaceous 

shale, crystalline limestone, dolomite, and intraformational conglomerate. The prevailing 

color of the strata is pale buff, but pinkish, 

purplish, and greenish hues occur. Many beds 

contain pinkish or purplish blotches ·and mot-. 

tlings. The upper portion. of the subdivision 

is relatively thick bedded; many beds ·attaining a thickness of 2 feet or more. The lower 

portion contains some beds as much as 1 foot 

thick but in general' is thin bedded. Toward 

the base the lamination becomes shaly and 

many layers are as thin a·s cardboard. Most 

of the subdivision forms a cliff or a steep ledgy 

slope broken by cliffs. 

The typical calcareous sandstone is hard, 

compact, and fine gra~ned, effervesces with 

acid, and is easily scratched with a knife. 

Weathered surfaces feel gritty and display 

indistinct cross-bedding, although freshly broken surfaces may exhibit no cross-bedded 

structure. Some beds are crystalline and consist entirely of calcareous material. Others 

contain more or less· fine quartzose and micaceous sand. It is·difficult to decide whether to 

classify some beds as limestone or as calcareous 

sandstone, but the cross-bedded structure 

indicates that the component material, whatever .its composition, is of clastic origin. 

The upper half of the subdivision is composed largely of the calcareous sandstone just 

described. Here and there a bed of pinkish or 

purplish crystalline limestone is interbedded 

with the calcareous sandstone. Beds of fine 

quartzose sandstone, sandy shale, and intraformational conglomerate appear at several 

horizons, and near the top of the subdivision 

there is a bed or two of dolomite similar to that 

in the overlying subdivision A. The lower 

half of the subdivision is composed partly of 

calcareous sandstone and partly of platy 

quartzose micaceous sandstone, sa:o.dy micaceous shale, and intraformational conglomerate. 

Worm markings are abundant, and some beds 

exhibit sun cracks and rippl~ marks. Scat-
PALEOZOIC FORMATION S OF THE GRAND CANYON. 45 

tered grains of glauconite occur in some beds. 

Most beds in the lower part of the subdivision 

do not effervesce with acid. 

Although intraformational conglomerate may 

appear at any horizon in subdivision B it does 

not form thick sets of beds and is not abundant 

in the subdivision as a whole. Most of it differs 

in composition from the conglomerate in the 

underlying subdivision in that, although composed chiefly of small fla~tened roUJ1ded pebble~, 

it is not essentially a lir,estone. Most of the 

pebbles a. re fine-grainer sandstone. ' and the 

matrix is fine sand. 

Subdivision A, at the top of the Muav, consists of hard buff limestone which forms massive 

beds from 2 to 10 feet thick. Thin partings ef 

sa:ndy . shale . separate ~e beds. T~e. lim~­ stone Is entirely cryst~lhne and :exhibits no 

bedded structure on fre~hly broken surfaces, 

but weathered urface~ ~how faint traces. of 

cross-bedding. Most f the rock contains 

small cavities, some of which are filled with 

crystalline material. Some beds. exhibit purplish blotches and mo tlings. Most beds do 

not effervesce with aci , although some effervesce feebly. The folio 'ng analysis shows the · 

composition of a typica specimen of the limestone from a bed 15 fee above the base of the 

subdivision in Bass Can 

Partial chemical analysis of li estone from subdivision A , 

Muav li estone. 

[Alfred A. C ers, analyst.] 

Insoluble ..................... , . . . . . 1. 52 

(Fe, Al) 20 3 ••••• _. ...... •. • • • • • • • • • • • • • • 80 

CaO ................................. 30.10 

MgO ................................. 20.78 

From this analysis it appears that the rock 

is a magnesian limestone that differs little in 

composition from typical dolomite. The small 

amount of insoluble material which the rock 

contains suggests that if, as the indistinct crossbedding indicates, the rock was composed 

originaJly of detrital sand, the sand was calcareous, not siliceous. 

These massive dolomites of subdivision A 

are the most resistant strata in the Tonto group 

and in consequence .of their hardness weather 

everywhere into strong cliffs. In appearance 

they are wholly unlike phe thin-bedded strata 

of the Bright Angel shale and lower Muav, resembling rather beds at the base .of the great 

cliff formed by the Red\valllimestone. How910480-23--4 

ever, they are separated from the Redwall cliff 

in Bass Canyon by 75 feet of thinly laminated 

beds that form a slope, so that the obt:;erver 

will experience no difficulty in distinguishing 

them from the Redwall strata. The upper 

limit of subdivision A is an unconformity of 

erosion, which is described on pages 49-51. 

Thickness and correlation.-The columnar 

sections in the Kaibab division of the Grand 

Canyon (seeP~. XX) in connection with Walcott's section at Kanab Creek (see Pl. XIX) 

trace ·the lithology of the Muav limestone 

through a distance of 50 miles southeastward. 

These sections show that the formation thins 

steadi~y . from northwest to southeast. The 

thickness at Kanab Creek is 685 feet; at Garnet 

Canyon, 504 feet; at Bass Canyon, 473 feet; at 

Slate Creek, 429 feet; at Hermit Creek, 419 

feet; at Pipe Creek, 383 feet; and at Cotton_; 

wood Creek (estimated), 238 feet. At Nunkoweap Valley the thickness is 425 feet, but this 

locality is 15 miles north of Cottonwood Creek. 

Thus the formation loses about two-thirds of 

its thickness in the 50 miles between Kanab 

Creek and Cottonwood Creek. The thinning 

is due pri~arily to -decrease in deposition, not 

to erosion, although at some places-for example, at Cottonwood Creek-more beds have· 

been removed below the erosional unconformity 

at the top of the Muav than at. others. 

The chief lithologic units into which the for-

. mation is divisible at Bass Canyon are recognizable in all the ·other sections, although 

it is difficult to trace from one locality to 

another the exact boundaries that limit the 

subdivisions, because the strata undergo gradual 

changes in Gomposition from place to pl,ace 

and the subdivisions grade into one another 

vertically. Broadly the lower two-thirds of 

the formation everywhere is thin bedded and 

consists of mottled limestone and interbedded 

sandy material, whereas the upper third is 

comparatively thick · bedded and consists of 

calcareous sandstone below and massive limestone above. Large parts of the for111ation, 

l).owever, become increasingly sandy toward 

the southeast. At · Kanab Creek the formation consists chiefly of limestone, whereas at 

Cottonwood Creek, 50 miles southea;;t of Kanab 

Creek, and at Nunkoweap Valley, 15 miles 

north ·of Cottonwood Creek, it consists chiefly 

of calcareo-arenaceous rocks. 
46 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

Most of the lithologic change occurs in subdivisions C and D. (See Pl. XX.) Thus at 

Bass Canyon subdivision D, at the base of the 

Muav, is 97 feet• thick and consists almost 

wholly of mottled limestone. Only 10 feet of 

limestone, at the base of the subdivision, contains interbedded layers of sandstone. At 

Slate Creek, southeast of Bass Canyon, the 

mottled limestone of subdivision D is 50 feet 

thick, and the basal 44 feet of the subdivision 

is .made up of alternating beds that consist 

chiefly of sandstone and shale but include a few 

layers of mottled limestone. That these prevailrngly sandy beds are actually a part of subdivision D as defined at Bass Canyon and are 

not equivalent to beds included in the Bright 

Angel shale · at Bass Canyon is clear, because 

the conspicuous soft green shale that marks 

the upper limit of the Bright Angel shale at 

Bass Canyon (see p. 34) is traceable continuously from Bass Canyon to Slate Creek. At 

Hermit Creek the mottled limestone of subdivision D is 40 feet thick and the underlying 

sandy beds 42 feet; and at Pipe Creek, still. 

farther southeast, the mottled limestone is 34 

feet thick and the sandy beds 51 feet. At the 

last two localities the mottled limestone interbedded with the sandy beds is very impure,_ so 

that the beds do not differ conspicuously from 

the Bright Angel shale and are difficult to separate from it. At Cottonwood Creek, southeast of Pipe· Creek, the mottled limestone at 

the top of subdivision D is only 25 feet thick 

and overlies beds of greenish sandstone which 

contain layers of impure mottled limestone in 

the upper 17 feet. Here I have placed the 

base of subdivision D at a point 37 feet below 

the 25-foot bed of mottled limestone. This 

horizon, as nearly as I could determine, is 

equivalent to that which marks the top of the 

Bright Angel shale at Bass Canyon, but the 

horizon is not actually traceable between Bass 

Canyon and Cottonwood Creek. Probably, 

however, my estimate of its position at Cottonwood Creek is correct within 25 feet. 

West. of Bass Canyon, at Garnet Canyon, the. 

mottled limestone is 122 feet thick and occupies 

all of subdivision D. A few thin layers of 

sandy material are interbedded with the basal 

6 feet of the limestone. 

Thus subdivision D decreases in thickness 

and undergoes a gradual change in composition 

southeastward through the Kaibab division. 

It decreases from 122 feet at Garnet Canyon 

to 62 feet at Cottonwood Creek, 28 miles 

southeast of Garnet Canyon. At Garnet 

Canyon it consists almost entirely of mottled 

limestone; at Cottonwood Creek it contains 

only a third as much mottled limestone as 

sandstone and shale, the limestone measuring 

only 25 feet. The increase of sandy material 

in the lower part of the subdivision makes its 

separation fr.om the Bright Angel shale increasingly difficult southeast of Bass Canyon. 

Subdivision C, . like subdivision D, decreases in thickness sou the as tward. At the 

type locality, at Bass Canyon, it is 241 feet 

thick. Southeast of Bass Canyon equivalent 

beds are 225 feet thick at Slate Creek, 215 feet 

at Hermit Creek, 185 feet at Pipe Creek, and 

176 feet at Cottonwood Creek. These correlations are necessarily approximate, because 

subdivision · C is nowhere separated from the 

overlying and underlying subdivisions by 

sharp lithologic changes, but . in general the 

limits of the beds correlated with subdivision 

C are believed to be correctly placed within 

25 feet. At all localities. the subdivision is 

prevailingly qalcareous but variable in composition1 thin beds of mottled limestone, in 

traformational conglomerate, sandstone, and 

shale succeeding one another in countless 

alternation, yet it contains much more limestone in proportion to sandy material at Garnet 

Canyon than at Cottonwood Creek and thus, 

like subdivision. D, becomes increasingly sandy 

toward the southeast. Glauconite, which occurs sparingly in the subdivision at Garnet 

and Bass canyons, becomes increasingly.abundant southeast of Bass Canyon. 

Subdivisions C and D together constitute 

that part of the Muav limestone in which 

thin-bedded mottled limestone is the prevailing rock and occupy the lower two-thirds of 

the formation. I have separated them at 

Bass Canyon, (1) because at that locality ' 

subdivision D consists essentially of mottled 

limestone, whereas subdivision C includes many 

interbedded layers of sandstone and shale; 

(2) because practically no limestone in subdivision D is of the intraformational-conglomerate type, whereas most of the limestone in 

subdivision C is intraformational conglomerate; 

and (3) because the two subdivisions differ in 

topographic expression, D forming a cliff and 

C forming a slope. ·Walcott in his sections at 
PALEOZOIC FORMATIONS OF THE GRAND NYON~ 47 

Kanab Creek and N unkoweap Valley (see Creek thin at :iass Can :Yon. It is therefore 

Pis. XIX and XX) does not subdivide this evident that th11 member as a whole becomes 

part of the Muav in which mottled limestone increasingly san . y southeastward from Kanab 

is the prevailing rock. Creek. -

The mottled limestone at Kanab Creek is Subdivisions A and B, which constitute the 

described by Walcott 20 as follows: upper third of t~e Muav at Bass Canyon, are 

represented by equivalent strata in all the 

The limestone is hard and brittle, breaking into angular sections shown o' Plates XIX and XX, ex~ept fragments. Arenaceous shaly partings occur at various 

horizons, and ill the section t Cottonwood Creek, where there is considerable arenaceous detrital 

matter mixed with the limestone. At the base a massive they have been r,emoved by erosion. 

bed 70 feet in thic'kness occurs, which is followed by The relatively lthick-bedded c.al~~reous sandseveral hundred feet of thin-bedded limestones. Many stone in the upper part of subdiVISIOn B of my 

layers are gray limestone full of small flattened fragments Bass. Canyon se,lction is e.videntl·y · equivalent [intraformational conglomerate?]. Toward the summit d k 

the upper 85 feet is essentially a repetition of the 70 feet to the gray and buff' calciferous san roc ' 50 

at the base. The entire mass has a thickness of 450 feet. feet thick, wh. ic1 constitutes subdivision B of 

The coralline mottling, as it has been called by authors, Walcott's' sectio at Kanab Creek, and to the 

extends from base to summit. That a portion of the yellowish saridst ne, 25 feet thick, wP,.ich conmottling is produced by the former presence of branching stitutes subdivi ion :2 of his section at Nuncorals may be true, but that such is usually the case is I · · B 

questioned. A study of the various forms of ramifying koweap_ Valley. Probably subdivisiOn as 

annelid trails and borings in the shales beneath prepares defined by me includes a wider range of strata 

us to look for the origin of the mottling in that direction. than the cori'esJonding subdivision as defined 

On the surface of the intercalated arenaceous shales and by Walcott, ar{J if so the thin-bedded sandalso of the shaly sandstone layers these trails are seen in stones of variaThle composition in the lower 

ablJ-ndance. They may be traced into the limestone I - b · I 

from the surface. Where the matrix is arenaceous they part of my sub1ivision B may e equiva ent 

are frequently calcareous, and in the calcareous layers to beds of lime~one at the top of Walcott's 

thev are often silicified. Usually of a purplish color, subdivision C a Kanab Creek and to beds of 

they may be gray or buff according to the material by calcareo-arenace us rocks at the top of his 

which they have been _ replaced. * * * I should subdivision 3 . ~t Nunkoweap Valley . . Subassign to annelids by far the greater share in the origin of division B as defned at Bass Canyon does not 

the mottling of the limestone. 

The 450-foot mottled-limestone member just 

· described constitutes subdivision c of Walcott's section at Kanab Creek and is undoubtedly roughly equivalent to subdivisions C and 

D of my Bass Canyon section. At Nunkoweap Valley it constitutes subdivision 3 of 

Walcott's section, is 340 feet thick, and · is a 

series of mottled and variegated calcareoarenaceous rocks. Thus it decreases from 450 

feet at Kanab Creek to 338 feet (the aggregate 

thickness of subdivisions C and D) at Bass 

Canyon, 30 miles southeast of Kanab Creek. 

Between Bass Canyon and N unkoweap Valley, 

30 miles to the northeast, the thickness changes 

very little, but between Bass Canyon and Pipe 

Creek, 18 miles to the southeast, it decreases 

from 338 to 270 feet, and at Cottonwood Creek, 

southeast of Pipe Creek, it appears t<? be less 

than· it is at Pipe Creek. Walcott's descriptions indicate that the Inember is much less 

sandy at· Kanab Creek than at Nunkoweap 

Valley and somewhat less sandy at Kanab 

20 Walcott, C. D., unpublished notes. 

appear to unde, go any significant litholqgic 

change in the t rea between Garnet Canyon 

and Pipe Creek. The ~hick-bedded calcareous 

sandstone in t~e upper P?rtion maintains ~ 

thickness of ab<j)ut 2:5 feet, whereas the subdivision as a wh~ble varies irregularly in thickness, being 78 fe t thick at Garnet Canyon, 72 

feet at Bass Can on, 95 feet at Slate Creek, 93 

.feet at Hermit Creek, and 87 feet at Pipe Creek. 

The fact 'that tlie boundary between subdivisions B and C iJ indefinite suggests that these 

variations may r:e only apparent, because in 

measuring some sectilons I may have nclu~ed 

in subdivision B beds that are actually equivalent to beds in the underlying subdivision C 

of . the Bass Can(Yon section. 

Subdivision 4 as defined at Bass Canyon 

consists of mas~ive buff crystalline limestone 

·whose composition is approximately that of 

dolomite and thich appears to be formed 

largely of calcarfous or dolomitic sand. This 

subdivision is constant in lithologic character 

in all the sectioJs between Garnet Canyon and 

Pipe Creek but exhibits many irregularities 
48 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

in thickness, owing . to the fact that its upper 

surface is an unconformity of erosion.. Its 

thi~kness is 70 feet at Garnet Canyon, 63 feet 

at Bass Canyon, 15 feet at Siate Creek, 29 feet 

at Hermit Creek, and 26 feet at Pipe Cre~k. 

In the region between Bass Canyon and Hermit 

Creek the beds of subdivision A have .been 

entirely removed at many places and a large 

part of the underlying subdivision B has been 

removed at .some pl~ces . . These variations in 

thickness show the character and relief of the 

surface produced by erosion after the beds of 

subdivision A were deposited but afford no 

evidence concerning the original thickness of 

the beds. 

Subdivision A is apparently equivalent to 

the massive mottled limestone, 60 feet thick, 

which constitutes subdivision 1 of Walcott's 

section at N unkoweap Valley and to the massive arenaceous and more or less mottled limestone, 185 feet thick, which constitutes subdivision a of his section at Kanab Creek. At 

Kanab 'Creek, at Nunkoweap Valley, and in the 

area between Garnet Canyon and Pipe Creek 

these limestones lie at the top of the Muav. 

Everywhere, therefore, they occupy the same 

stratigraphic position with regard to the underlying beds of calcareous sandstone of subdivision B. Moreover, if it is assumed that the 

sand in Walcott's limestones is calc'areous, 

they do not appear to differ conspicuously 

from the equivalent beds in the area between 

Garnet Canyon and Pipe Creek. Some of the 

beds in this intermediate area exhibit purplish 

blotches and mottlings, and all of them, like 

Walcott's beds, are massive. Inasmuch as the 

top of subdivision A is eroded at Kanab Creek . 

and at Nunkoweap Valley as well as in the in- . 

termediate area it is impossible anywhere to 

determine the original thickness of the su bdivision and consequently of the Muav limestone. 

Frech's section 21 at "Congress Canyon'' 

(Red Canyon), 3 miles east of Cottonwood 

Creek, shows only 129 feet of strata at the summit of the Tonto group that can be confidently 

assigned to the Muav limestone. Probably he 

has included strata in the Redwalllimestone 

which are actually equivalent to the Muav and 

Temple Butte limestones, because the thickness of 1,000 feet which he assigns to the Redwall at that locality is certainly too great by 

several hundred feet. 

· 21 Frech, F .. op. cit., p. 479. 

Fossils.-Fossils are scarce in the Muav· 

limestone. At Kanab Creek, from the lower 

bed of mottled limestone in subdivision c of 

his section, Walcott 22 obtained the following 

species: 

Hyolithes primordialis? 

Lingulepis prima?· 

Acrotreta? sp. 

Orthisina sp. 

Ptychoparia sp. 

Bathyurus? sp. . 

This bed of mottled limestone is probably 

roughly equivalent to my subdivision D of the 

Muav at Bass Canyon. (See pp. 43-44.) 

From the upper bed of mottled limestone 

in subdivision c at Kanab Creek Walcott 

obtained the forms listed above and in addi-

.tion a species of Lingula. . This mottled limestone is probably equivalent to beds in the 

upper part of my subdivision C at Bass Canyon. 

From beds in the upper part of the Muav 

limestone at Kanab Creek which are probably 

equivalent to my subdivision A at Bass Canyon 

Walcott obtained a species of Trematis and an 

imperfect specimen of Discina. 

At Nunkoweap Valley the beds at the top of 

the Muav which are equivalent to my subdivision A at Bass Canyon are reported by W alcott to contain Lingulepis and Ptychoparia. 

(See columnar section at Nunkoweap Vall,ey, 

Pl. XX.) 

In the area covered by my sections between 

Garnet Canyon and Cottonwood Creek I have 

obtained fossils from the Muav limestone at 

only one locality. At Hermit'Creek, from a 

bed of mottled limestone in subdivision C, · 

118 feet above the base of the subdivision, I 

collected 

Finkelnburgia sp. 

Syntrophia sp. 

Anomocarella sp. 

Pagodia? sp. 

Ptychoparia? sp. 

The locality is on the west slope of Cope 

Butte a few hundred feet north of the Hermit 

trail. The fossils were identified by Edwin 

Kirk, who states: 

The fauna as shown in the collection might be either 

Middle or. Upper Cambrian. I think more extensive collections are needed definitely to prove its age. In this 

connection a faunal list given by Walcott 23 might be of 

interest. This fauna is cited from the Tonto at Kanab 

Creek and is given as Upper Cambrian. 

22 Walcott, C. D., unpublished notes. 

2s Walcott, C. D., U. S. Geol. Survey Mon. 51, p.214, locality 75, 1912. 
PALEOZOIC FORMATIONS OF THE GRAND CANYON. 49 

At Hermit Creek, from a bed in subdivision 

C, 50 feet lower than that in which I found the 

fossils listed above, Schuchert 24 obtained 

pygidia of Saukia and of Neolenus. In discussing the fossils collected at Hermit Creek he 

states, "These fossils, and more especially the 

trilobites, show that the Muav is of Upper 

Cambrian age." · 

Regarding the age of the Muav limestone 

Walcott 25 states: 

As far as can be determined from the present collections 

I should include the Muav limestone in the Upper Cambrian; the Bright Angel shale and Tapeats sandstone in 

the Middle Cambrian. However, it is very desirable that. 

larger collections be made from the Muav limestone. 

Therefore I have assigned the Muav limestone to the Upper Cambrian in the present 

report, although I realize that further collections of fossils are necessary before its age 

can be fixed definitely. A careful search for 

fossils at the top of the formation may yield 

interesting results, for if the Muav is in fact 

Upper Cambrian it is conceivable that strata 

younger than Cambrian and older than Upper 

Devonian may be preserved in some places 

beneath the surface of erosion at the top of 

the formation. 

UNCONFORMITY BET.WEEN CAMBRIAN AND 

DEVONIAN SYSTEMS. 

Walcott has shown that both at Kanab 

Creek 26 and in the region about Nunkoweap 

Valley, 27 50 miles southeast of Kanab Creek, 

the upper limit of the Tonto group is an unconformity. The unconformity at Kanab 

Creek he describes as a strong line of erosion 

that in places exhibits vertical irregularities 

of 80 feet within horizontal distances of a few 

hundred feet. In studying the Tonto group 

between Garnet Canyon and Cottonwood 

Creek I have traced this unconformity through 

a distance of about 28 miles in the south wall 

of the Grand Canyon in the Kaibab division. 

(See Pl. XX.) Probably, therefore, it extends continuously from Kanab Creek to 

Nunkoweap Valley. Further study may show 

that it extends far west of Kanab Creek. 

Inasmuch as the unconformity lies within 

horizontal strata it can not be detected by 

24 Schuchert, Charles, op. cit., p. 369. 

25 Walcott, C. D., personal communication. 26 Walcott, c. D., The Permian arid other Paleozoic groups of the 

Kanab Valley, Ariz.: Am. Jour. Sci., 3d ser., vol. 20, pp. 221-225, 1880. 27 Walcott, C. D., Pre-Carboniferous strata in the Grand Canyon of 

the Colorado, Ariz.: Am. Jour. Sci., 3d ser., vol. 26, p. 438, ~883. 

discordance of dip and is plainly recognizable: 

only where the eroded surface exhibits strong: 

relief. IIi places where the eroded surface, 

is level or ne~rly level, as, for example, at. 

Bass Canyon and at Cottonwood Creek, the 

unconformity is obscure. Even where the 

surface is moderately irregular, as in the region about the Hermit and Bright Angel 

trails, the visitor may ·at first experience, 

considerable difficulty in recognizing the unconformity until he knows exactly where to· 

look for it. 

At present the Hermit and Bright Angel 

trails afford the visitor the easiest opportunity 

to examine the unconformity. If he will 

descend either of these trails to a point about. 

a hundred feet below the base of the sheer 

cliff formed by the Redwall limestone, pick 

out the beds of massive cliff'""making dolomite 

that constitute the topmost subdivision of the 

Muav limestone (see PL XX), and follow 

their upper surface, he will find broken..:down 

areas in the top of the dolomite cliff, which ~t 

first sight may appear to be caused by masses 

of rock breaking off from the cliff but which 

close inspection will show . to be hollows 

eroded in the dolomite and filled by overlying 

strata. As a rule the strata in the hollows 

exhibit pale purplish or pinkish tints, which 

contrast slightly with the prevailing buff or 

gray of the dolomite, although in many places. 

their color is obs¢ured ·by buff and gray stains; 

washed over them fron1 overlying beds. Moreover, they are softer than the dolomite and 

are irregularly bedded, so that they weather 

more easily than the 'dolomite and form 

slopes. Commonly, these slopes are wholly or 

partly covered with talus. · 

In the canyon of Garden Creek, through 

which :the Bright Angel trail descends from 

the rim of the Grand Canyon at El Tovar, a 

hollow of the type just described is well exposed near the north end of the prom on tory 

that separates the canyon of Garden Creek 

from that of Pipe Creek. This hollow lies 

about half a mile east of Indian Garden and 

may be' . reached by leaving the trail . near 

Indian Garden . and climbing the long slope of 

Bright Angel shale and Muav limestone east 

of the Garden. Other hollows are exposed 

in the canyon of Garden Creek which the vis~ 

itors will easily discover when he has learned 

where to look for thern: The can"yon of Pipe. 
50 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

Creek, east of Garden Creek, contains at least. 

ten of them. Several are exposed in each of 

the canyons west of Garden Creek, between 

Garden Creek and Hermit Creek. 

called "Long Drag" and climb eastward several 

hundred feet up the steep ledgy slope formed by 

subdivisions C and B of the Muav limestone, 

following a contact between bare rock on his 

Temple Butte left and talus on his right. The hol-

==~.:;!1:;t1a~~;t~;~:x:~=e;),e:;J;:::f .. ;i,:~.:fi :J~::j1E'5[~)1: -~ !:::, ~;ra~ !..:-::· , .. . A::~~:::::. :~ !~ed~~:t~\!~ ~ft i~e:::::a~:~ ·~·~'t ... _@.:, ':.::f·@ .. ,+·:~:::::v .::·.::: (' :f- :: :: ·:· .~~' "'''·~ .. ::·.'.J.;-.·d B by talus, and the observer may 

a doubt its existence until he actually reaches it. 

0 

c 

h 

Approximate scale 100 200 300 400 500 FEET ~~--~--~--~~ 

c 

FIGURE 3.-Dlagrammatlc sketches showing general character of unconformity between Temple Butte limestone and Muav limestone at 

eight localities between Garnet Canyon and Cottonwood Creek, Grand 

Canyon, Ariz. a, Garnet Canyon; b, Bass Canyon; c, Ruby Canyon; 

d, Turquise Canyon; e, Slate Creek;/, Hermit Creek; g, Pipe Creek; 

h, Cottonwood Creek. 

The north end of the hollow affords good exposures of the gnarly, irregularly bedded pinkish 

or purplish calcareous sandrock that constitutes the typical deposit of known Devonian 

age in this part of the Grand Canyon (seep. 51), 

so that to one interested in the stratigraphy 

the hollow is well worth a visit because of its 

accessibility. A similar hollow is exposed on 

the west side of the canyon of Hermit Creek 

about a mile west of the hollow just described. 

It lies near the north end of the promontory 

that separates the canyon of Hermit Creek from 

the next large canyon west of it~ 

By far the best exposures of the unconformity 

which I have seen in the Grand Canyon are in 

the region between Hermit Creek and Bass 

Canyon, in the long straight canyons that head 

behind Diana, Pollux, and Castor temples, 

namely, Slate Creek; Agate, Sapphire, and Turquoise canyons; also in Ruby Canyon, 2! miles 

southeast of Bass Canyon. In all these canyons the surface of erosion is irregular in many 

places, so that the unconformity is plainly evident at first sight, even when viewed from a considerable distance. This interesting region, 

however, is not easily accessible to the tourist. 

The accompanying sketches of the uncon-

• formity (fig. 3) show the topographic character 

of the eroded surface at eight different localities 

between Garnet Canyon and Cottonwood Creek. 

The photographs reproduced in Plates XXII 

and XXIII, A, show details of the unconformity. At Garnet Canyon the surface is comparatively even and exhibits no narrow hollows. 

Depressions are eroded in it, but they appear 

to be so broad and fiat that the general aspect 

of the surface is mesa-like. At Bass Canyon, 3 

miles from Garnet Canyon, the surface is pracIn the canyon of Hermit Creek a hollow 

nearly 80 feet deep lies in the northern slope of 

Cope Butte just east of and above the Hermit 

trail. To reach this hollow the visitor should 

leave the trail at the lower end of the tt;tngent 

tically level, and I have observed only one 

irregularity in it in a distance of several thousand feet. This irregularity is a steplike drop 

of about 25 feet from one mesa-like level to 

another. At Ruby Canyon, 2! miles from 

Bass ·Canyon, the surface is very uneven. The 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 131 PLATE XXII 

A. 

B. 

UNCONFORMITY BETWEEN TEMPLE BUTTE LIMESTONE AND MUAV LIMESTONE IN WEST WAJ..L 

OF CANYON OF SLATE CREEK, SHINUMO QUADRANGLE, ARIZ. 

a, Redwalllimestone; b, Temple Butte limestone; c, Muav limestone; y, z, subdivisions A, B of Muav limestone. The 

human figure just at the right of the sharp bend in the unconformity in A, gives an idea of the scale of the photograph. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 131 PLATE XXIII 

A. UNCONFORMITY BETWEEN TEMPLE BUTTE LIMESTONE AND MUAV LIMESTONE IN WEST 

WALL OF TURQUOISE CANYON, SHINUMO QUADRANGLE, ARIZ. 

a, Redwall limestone; b, Temple Butte liniestone; c, conglomerate; d, Muav limestone; Y; z, subdivisions A, B of Muav limestone. 

B. UNCONFORMITY BETWEEN HERMIT SHALE AND SUPAI FORMATION AT RED TOP, ON HERMIT 

TRAIL, BRiGHT ANGEL QUADRANGLE, ARIZ. 

a, Kaibab limestone; b, Coconino sandstone; c, Hermit shale; d, Supai formation; e, artificialfill below trail. 
PALEOZOIC FOR,MATIOlQ"S OF THE GRAND CANYON. 51 

depressions in it are numerous, irregular _in profile, and comparatively narrow. Some of these 

hollows are 40 feet deep. At Turquoise Canyon, 2! miles from Ruby Canyon, the hollows 

are less numerous but are broader and deeper 

than they are at Ruby Canyon. Some are 80 

feet deep. In profile they are irregular, like 

those at Ruby Canyon. At Slate Creek, 3 miles 

from Turquoise Ca;nyon, the hollows are broad 

and deep but are more symmetrical in profile 

than those at Ruby Canyon. At Hermit Creek, 

5 miles· from Slate Creek, they are symmetrical; 

broad, and deep but 'are much less numerous 

tHan ·at·Slate·Cfeek. At Pipe Creek; 5! ·miles 

from··Hermit Creek; they are s~allower and narrower than at Hermit Creek but otherwise resemble those at Hermit Creek. Southeast of 

Pipe Creek they disappear, and at Cotto,nwood 

Creek, 7 miles from Pipe Creek, the unconformity is represented by a slightly wavy surface 

which does not appear to exhibit vertical irregularities of more than 3 or 4 feet in horizontal 

distances of hundreds of feet. 

In the region between Ruby Canyon ·and 

Pipe Creek the hollows look like cross sections 

of ancient stream valleys. If they ~re, I b~­

lieve it would be possible by studying and mapping the hollows between Slate Creek and Ruby 

Canyon to identify certain . ancient valleys in 

opposite walls of a canyon, trace them through 

the narrow promontories separating the canyons, and thus by restoring in imagination their 

courses over a considerable area determine their 

direction and grade. 

DEVONIAN SYSTEM. 

TEMPLE BUTTE LIMESTONE. 

Although the' upper limit of the Tonto group 

is clearly defined by the unconformity just described, the correlation of the beds that lie 

between this unconformity and the sheer cliff 

of the Redwalllimestone is a difficult problem. 

The beds differ from place to place in thickness, 

character, and succession and are not separated 

from the overlying Redwal_l strata, of known 

Mississippian age, by a sharp stratigraphic 

break like the unconformity at the summit of 

the Tonto. Some beds are unquestionably of 

Devonian age, and others may be Mississippian, 

but owing to their variation in character and 

succession and to the absence of sharp stratigraphic breaks their separation can be established definitely only by the al.d of fossils. 

Many beds contain obscure traces of life, but · 

determinable forms are scarce and the beds are 

difficult to reach in many places where it seems 

desirable to 'study them. It will be necessary 

to make a more thorough study of the beds th~n 

I have yet attempted, and particularly to ma~e 

a systematic search for fossils in them, before 

the~ir age and correlation. can be established in 

detail. Meanwhile the corr~lations . presented 

in this report -(see Pl. XX) should be regarded 

as tentative. 

. Fortunately one type of deposit that can be 

recognized wherever it is present by its peculiar 

lithologl.c. character has yielded fossil~ at one 

locality which conclusively establish. its' age 

as Devonian. This deposit is an irregularly · 

bedded, gnarly pinkish or purplish calcareous 

sandrock which fills hollows in the surface 

marked by the unconformity. It is exposed 

most typically in the canyons between Ruby 

Canyon and Pipe Creek (see fig. 3 and Pl. XX) 

and is apparently represented by equivalent 

beds at Garnet Canyon and at Cottonwood 

Creek. It is not exposed at Bass Canyon. 

Apparently it is the oldest deposit l~id down 

upon the post-Tonto surface in this part of the 

Grand Canyon. 

The locality where I found fossils in the deposit is in Sapphire Canyon, at an elevation of 

about 3, 700 feet, in the main stream course of 

the canyon. At this point the deposit fills a 

depression about 50 feet deep eroded in the 

Muav limestone. , It consists essentially of 

irregularly bedded calcareous sandrock whose 

component grains are chiefly calcareous or 

dolomitic sand; the rock might .thus he classed 

either as limestone or as sandstone. Some 

beds, however, are compact crystalline limestone or dolomite, and some are coarse conglomerate. A few beds consist of bright-red finegrained friable sandstone or sandy shale which 

resembles the Hermit shale higher in the 

canyon wall. (See p. 64.) . In places this red · 

sandstone shows concretionary structure, and 

some beds exhibit sun cracks. Prac.tically 

all the calcareous sandrocks and associated 

beds- are in lenticular layers which are highly 

irregular and are of no great horizontal extent, 

co:rnmonly wed.ging out within distances of less 

·than 100 feet. Local unconformities are common between the beds . . No two vertical sections of the deposit are alike, even in the same 

hollow. T~e prevailing color of the beds is 
52 SHORTER CONTRIBUTIONS TO GENER.AL GEOLOGY, 1922. 

' pinkish or purplish gray, but some beds display 

green or yellowish tints, and some are white or 

cream-colored. In many places the colors are 

mingled in blotches and streaks. Most of the 

rock is moderately fine grained, and nearly all 

of it exhibits cross-bedded structure. - In many 

parts of the deposit, but particularly at the top, 

the bedding is curiously gnarled and contorted. 

Probably this gnarly structure is an irregular 

form of cross-bedding. 

The fossils occur in the lower part of the 

deposit, most of them within 3 feet of the base. 

They are abundant but are fragmentary and 

poorly preserved. A few fragments are syattered . through higher beds. The following 

analysis of a representative sample of the rock 

in which the fossils· occur shows that the rock 

is an impure dolomite. 

Partial chemical analysis of limestone from Sapphire Canyon. 

[Al!red A. Chambers, analyst.] 

Insoluble. . . . . . . . . . . . . . . . . . . . . . . . . . . 10. 96 

(AI, Feh03 •••••••••••••••••• .. • • • • • • 2. 89 

CaO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27. 43 

MgO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17. 88 

The fossils are scales and plates of fishes. 

The material which I collected was examined 

byJ. W. Gidley, who writes: 

I have gone over your collection critically and :find only 

Bothriolepis represented in the lot. The material is too 

fragmentary to be determined specifically. However, the 

form represented appears to agree rather more closely with 

an Eastern species, B. nit1:dus, found in the Catskill 

formation, than it does with the common western form, 

B. canadensis. This, however, is not important for your 

purpose, except that it certainly indicates Upper Devonian. , 

So far as I know, Bothriolepis is characteristic of the 

Upper Devonian and is not known to occur below the 

Middle Devonian. 

In addition I may state that in the character of the rock 

and broken ·condition of the :fish remains your collection 

is very similar to the Catskill material. 

The deposits of the type just described can 

therefore be assigned without question to the 

Devonian Temple .Butte limestone, which, 

according to Walcott, 28 "is unmistakably 

marked by thin purplish-colored layers of 

fine-grained sandstone that pass into calcareous 

sandrock and limestone in which cyathophylloid corals, casts of brachiopods and gastropods, 

and plates of placoganoid fishes usually occur." 

Fossils will probably be found {n other localities than the one in Sapphire Canyon when 

systematic search is made for them. 

28 Walcott, C. D., Pre-Carboniferous strata in the Grand Canyon of the 

Colorado, Ariz.: Am. Jour. Sci., 3d ser., vol. 26, p. 438, 1883. 

, 

The deposits just described are essentially 

similar wherever they are exposed, although 

they may differ somewhat in lithologic detail. 

At Turquoise Canyon, for example, they 

contain many lenses of conglomerate, whereas 

at many other localities they may contain 

little or none. At some places they may 

contain no bright-red sandstone or shale, and 

at some places little or. no limestone or dolomite. 

Calcareous sandrock characterized by gnarly 

or contorted bedding, however, is always 

present. At Turquoise and Sapphire canyons 

and at the canyons of Slate and Hermit 

creeks the upper part of the deposits consists 

wholly of g:qarly sandrock, which forms a 

massive, rather distinct bed from 20 to 25 feet 

thick. Commonly the upper part of this bed 

extends over the top of the higher Cambrian 

knolls to a depth of 5 to 15 feet. 

At Bass Canyon. the massive dolomite (subdivision A) at the top of the Muav limestone is 

overlain by 75 feet of thin-bedded purplish to 

white sandy limestone which is mottled in 

places by worm markings and contains a few 

beds of intraformational conglomerate similar 

to that in the Muav limestone. This thinbedded limestone contains no determinable fossils, . although one bed contains obscure forms 

that- are probably cup corals. A detailed 

section of the limest.one is given on pages 32-33. 

The following analysis shows the composition 

of a sample of the limestone taken from bed 

14, at the base of the section: · 

Partial chemical analysis of limestone from bed 14, · Temple 

Butte limestone. 

(Alfred A· Chambers, analyst.j 

Insoluble. . . . . . . . . . . . . . . . . . . . . . . . . . . 24. 41 

(AI, Fe)20 3 ......................... 1. 83 

CaO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22. 95 

MgO ............ ~ . . . . . . . . . . . . . . . . . . 15. 01 

The rock is therefore an impure magnesian 

limestone or dolomite. The insoluble impurities are probably largely quartzose sand. 

The beds of sandy limestone are overlain by a 

massive bed of brecciated limestone (see p. 

32), which lies at the base of the Red wall cliff. · 

Both upper and lower surfaces of this brecciated 

limestone are wavy, but I am not. sure that 

they represent planes of erosion. At any rate 

the brecciated bed marks an abrupt ch~nge in 

lithology, and I have placed it at the base of 

the Mississippian Redwall. 
PALEOZOIC FOR,MATIONS OF THE GRAND CANYON. 53 

At most places in Bass Canyon the contact 

between the thin-bedded sandy limestone and. 

the underlying massive dolomite of the Muav 

limestone is an even line, so that the two "formations appear to be conformable. But at 

Garnet Canyon, 3 miles west of Bass Canyon, 

and at Ruby Canyon, 2 miles southeast of 

Bass Canyon, the thin-bedded sandy limestone 

is separated from the Muav by a plain line of 

erosion. (See fig. 3.) The contact is therefore 

an unconformity. 

I have assigned the 75 feet of thin-bedded 

sandy limestone exposed at Bass Canyon to the 

Devonian Temple Butte limestone, because at 

Garnet Canyon (see Pl. XX) similar beds 

overlie a gnarly purpli~h conglomeratic sand..; 

rock that resembles the deposit in which fish 

remains occur in Sapphire Canyon and are 

overlain by other beds of gnarly conglomeratic 

sandrock and red shale, so that at Garnet 

Canyon the thin-bedded sandy limestone is 

actually included within beds that are lithologically identical with the known Temple 

Butte limestone. 

POSSIBLE UNCONFORMITY BETWEEN DEVONIAN 

AND CARBONIFEROUS SYSTEMS. 

Walcott 29 has shown that at Kanab Creek 

the Red wall limestone is separated from underlying Devonian beds by a line of erosion, but I 

am unable confidently to trace this unconformity in the region between Garnet Canyon and 

Cottonwood Creek and at all places to separate 

Devonian beds from the Redwalllimestone. 

At Hermit Creek the sequence of beds between the Devonian Temple Butte limestone 

and the Redwall strat a of known Mississippian 

age is as follows: 

Section in western slope of Cope Butte, near Hermit trail. 

[For profiles of section see Pls. XIX and XX.] 

Massive gray magnesian limestone of known 

Mississippian age forming lower part of sheer 

Feet. 

0 

RedwaJl cliff............................... 80± 

1. Alternating beds of gray magnesian limestone, 0 

buff sandstone, and chert; partly concealed; 

form slope.................................. 15 

2. Massive gray vesicular cry~talline magnesian 

limestone; cavities contain coarse crystals of 

of calcite; forms cliff ...................... .' . 11 

3. Concealed beds; form slope................... 6 

4. Limestone like bed 2; cliff.................... 7 

29 Walcott, C. D., The Permian and other Paleozoic groups of the Kanab Valley, Ariz.: Am. Jour. Sci., 3d ser., voL 20, PP· 221-225, 1880. 

Feet. 

5. Band of chert layers; weathering black........ 1 

6. Limestone like bed 2; cliff. . . . . . . . . . . . . . . . . . . . 7 

7. Buff sandstone with bands of chert............ 5 

8. Limestone like bed 2; cliff.................... 7 

9. Buff sandstone with bands of chert............ 2 

10. Limestone like bed 2 but sandy; slope......... 4 

11. Sandy conglomerate composed largely of fragments of calcareous sandrock; cliff; base of 

bed uneven, wavy.......................... 1-3 

Gnarly purplish and white calcareous sandrock 

of known Devonian age (Temple Butte limestone) lying in hollow eroded in Muav limPstone; upper surface of sandrock uneven, 

wavy; in places exhibits inequalities of 3 

feet ................... _.......... . . . . . • • . . 14-76 

The following analysis of a representative 

sample of the limestone forming bed 8 of the 

foregoing section probably shows approximately the composition of beds 2, 4, and 6 as 

well, because none of these beds differ in 

appearance. 

Partial chemical analysis of limestone from bed 8; Cope Butte. 

[Alfred A. Chambers, analyst.] 

Insoluble ............................ " 0. 4 7 

(Al, Fe)20 3 ........ ,.................. • 41 

CaO ............ .' . . . . . . . . . . . . . . . . . . . . 31. 79 0 

MgO ...... ; ......... :. . . . . . . . . . . . . . . . 19. 65 

The limestone is 0 therefore a practically pure 

dolomite, and it is interesting to note that tho 

chemical composition of this rock is almost exactly that of the overlying limestone, which 

forms the lower part of the Redwall cliff (see 

analysis, p. 55) and from which, indeed, the 

limestone of bed 8 is almost indistinguishable 

in appearance, differing only 0 in the thickness 

of the bedding. 

Because the limestones in the series of beds 1 

to 11 of the above section are lithologically 

identical with the beds at the ba~e of the overlying Redwall limestone I have assigned the 

series to the Redwall limestone. The lithologic change froin these beds to the gnarly 

sandrock underlying them is sharp, and it is 

possible that the wavy line at their base marks 

an erosional unconformity which separates the 

Devonian from the Mississippian. Ho}Vever, I 

do not wish unduly to emphasize the importance of the latter feature, because wavy surfaces occur at many horizons in the Redwall 

and Temple Butte limestones and are I?-Ot necessarily of widespread stratigraphic significance. 

Massive beds of gray vesicular magnesian 

limestone that alternate with layers of sand <?r 
54 SHOR.TER CONT'RIBUTIONS TO GENERAL GEOLOGY, 1922. 

chert and are similar to the series at Hermit 

Creek just described are exposed at Turquoise 

Canyon and in the canyons of Slate, Pipe, and 

Cottonwood creeks, where I have also assigned 

them to the Redwalllimestone. (See Pl. XX.) 

Apparently the series thickens southeastward 

and attains a thickness of more than 100 feet 

in the region about Cottonwood Creek, but I 

have examined it in detail only at Hermit 

Creek. At Turquoise Canyon and Slate Creek 

it is underlain by 15 to 20 feet of thin-bedded 

sandy purplish and whitish magnesian limestones; those at Slate Creek I have assigned 

tentatively to t4e Temple Butte limestone 

(see Pl. XX), because they resemble the thinbedded Temple Butte limestone at Bass Canyon (see _pp. 51-53), althoughitispossible that 

they belong at the base of the Redwall limestone, for they are separated from underlying 

gnarly sandrock of Devonian age by a slightly 

wavy surface. At Bass Canyon no beds at 

all resembling the massive vesicular limestones 

of Hermit Creek appear below the base of the 

Redwall cliff. The lithologic change from 

typical Redwall beds to ·the thin-bedded purplish sandy limestone of the Devonian takes 

place at a brecciated bed at the very base of 

the cliff, and the plane·of separation, as stated 

on page 53, may or may not be an unconformity. 

At Garnet Canyon all beds above the known 

Devonian are inaccessible. An uneven surface 

is exposed there at the top of the · highest 

beds that I could reach, but I do not know 

whether this surface is an unconformity separating Devonian and Mississippian or only a 

local unconformity in the Temple Butte limestone. 

In brief, if an unconformity separates the 

Terriple Butte 1imestone and the Redwalllimestone in the region which I have examined, it . 

is so obscure and exhibits so little irregularity 

that it can be detected only by obtaining.determinable fossils in the strata within which it 

lies. Certainly no surface of erosion exists 

which is at all comparable in irregularity with 

that which separates the Tonto group from 

overlying beds. 

CARBONIFEROUS SYSTEM. 

MISSISSIPPIAN SERIES. 

REDWALL LIMESTONE (RESTRICTED). 

Definition.-In previous publications the 

Redwall limestone has been classified as of 

Pennsylvanian and Mississippian age. As originally defined by Gilbert 30 the formation was 

((named 'from the red appearance of its escarpments on either side of the Grand Canyon" and 

included in its top 2oo·to 510 feet of alternating 

sandstones and limestones of ((Coal Measures" 

(Pennsylvanian) age. Later writers have also 

included these Pennsylvanian beds in the Redwall, although Darton 31 in 1910 expressed the 

belief that they properly belonged to the overlying Supai formation. In the present report 

these beds of Pennsylvanian age are transferred 

to the Supai formation, to which, by reason of 

their lithology, age, and probable unconformable contact with the Mississippian rocks, they 

seem more properly to belong. The name Redwalllimestone is therefore here restricted to the 

massive gray crystalline limestones of Mississippian age, and this restricted definition has 

been adopted by the United States Geological 

Survey. 

Oharacter.-The Redwall limestone as here 

restricted consists almost wholly of bluish-gray 

crystalline limestone whose distinctive features 

are massive appearance, hardness, and relatively great thickness. The massive appearance of the limestone is due partly to the thickness and homogeneity of the beds but chiefly 

to the fact that the planes of separation between many beds are inconspicuous, so that 

when viewed from a distal).Ce large parts of the 

formation present the appearance of a single 

stratum. The hardness and thickness of the 

limestone cause it to make the sheerest and 

most continuous cliff in the canyon wall. 

At Bass Canyon the Redwall limestone is 

about 570 feet thick and is divisible into three 

parts which differ in topographic expression. 

Subdivision C, at the base of the formation, 

makes a slope that unites with the steep ledgy 

slope formed by the Temple Butte limestone 

(seep. 32) and is a bed of sandy hreccia 8 feet 

thick whose fragments consist chiefly of gray 

limestone. It is overlain by bluish-gray massive crystalline limestone, obscurely bedded at 

the base and top, which makes a cliff approximately 500 feet high.. This cliff-making limestone constitutes subdivision B. Subdivision 

A, at the top of the formation, consists of distinctly bedded bluish-gray crystalline limestone which includes a few thin partings of red 

80 Gilbert, G. K., U.S. Geog. and Geol. Surveys W.lOOth Mer. Rept., 

vol. 3, pp. 161, 162, 177, 178, 185, fig. 82, 1875. 

81 Darton. N. H., A reconnaissance of parts of northwestern New 

Mexico and northern Arizona: U.S. Geol. Survey Bull. 435, p. 22, 1910. 
c P ALEOZOIO FORMATIONS . OF THE GRAN:D CANYON. 55 

shale. This subdivision, 62 feet thick, n1akes 

a succession of small cliffs and narrow ledges 

above the sheer cliff formed by subdivision B. 

. The character and succession of the Redwall 

beds are described in the sections given on pages 

31-32, and the profiles of the subdivisions are 

shown in the columnar section (Pl. XIX). 

. Subdivisions A and C can not be traced 

vvith certainty far from Bass Canyon, but 

subdivision B, the main cliff-making portion 

vf the Redwall, is constant in lithology and in 

appearance and is readily recognizable everywhere in the Kaibab division of the Grand 

Canyon. The upper and lower portions of 

the subdivision are obscurely and heavily 

bedded, whereas the middle portion is distinctly bedded and contains many thin layers 

of chert and sand. Most beds in the subdivision contain a fe~ scattered nodules of 

chert, but chert is conspicuously abundant 

only in the middle, distinctly bedded portion. 

Many beds contain coarse crystals of calcite, 

some of which line cavities, some of which 

form large irregular masses in the rock, and 

some of which form layers a few inches to a 

foot thick. Interbedded layers of sandstone 

occur throughout the subdivision but are 

numerous only in the middle portion. As a 

rule the sand is loosely cemented and exhibits 

gnarly structure. Many beds rest on irregular, · 

wavy surfaces. In many places the limestone 

cliff is stained pinkish or pale rose color by 

ferritic pigment washed over it from overlying 

red shales in the Supai formation. Unstained 

surfaces of the limestone commonly weather 

gray or bluish gray. Freshly broken surfaces 

are gray, buff, or white. · 

The following analyses show the composition of representative samples of limestone 

from subdivision B at Bass Canyon. No. 1 

represents the obscurely bedded limestone 

(No. 1, p. 32) that forms the upper part of the 

subdivision; No. 2, the heavily bedded limestone (No. 3, p. 32) that forms the lowerpart: 

Partial chemical analyses of limestone from subdivis£on B , Redwalllimestone. 

[Alfred A. Chambers, an'llyst. 

Insoluble ... __ . . _. _____ ._ ... _ ..... _ 

(Al, FehOa-----------------------

CaO ... --------------------------- MgO.-----------------------------

0.48 

. 10 

55. 50 

. 08 

0. 82 

. 40 

32. 54 

19. 52 

These analyses show that the limestone at 

the top of the subdivision is' practically pure, 

whereas that at the base is· magnesian and is 

essentially dolomite. The composition of the . 

limestone forming the middle, laminated member of the subdivision was not determined by 

analysis, but inasmuch ·as this limestone 

resembles that in the overlying obscurely 

bedded member in .appearance and effervesc.es 

freely with acid, it is probably not magnesian. 

The limestones in subdivision A resemble 

those in the upper part of subdivision B and 

effervesce freely with acid. It would appear, 

therefore, that the. limestone in the whole 

upper portion of the Redwall is comparatively 

pure and only that in the basal member of · 

subdivision B is magnesian. 

Southeastward from Bass Canyon subdivision B diminishes gradually but steadily in 

thickness. At Bass Canyon it is approxi-:-

mately 500 feet thick; at Hermit Creek, 13 

miles southeast of Bass Canyon, 4 7 5 feet; and 

at Red Canyon, 16 miles farther southeast, 375 

feet. Red Canyon is 4 miles east of Cottonwood Creek. This decrease in the thickness 

of subdivision B is readily apparent to most 

observers in the diminished height of the Redwall cliff when seen from Grandview or Desert 

View, as contrasted with the height of the 

cliff when seen from the head of the ij:ermit 

trail or from Bass Camp. 

Subdivision A as defined at Bass Canyon is 

traceable southeastward at least as far as 

Hermit Creek (see columnar sections, Pl. XIX), 

but subdivision Cis not traceable southeast of 

Ruby Canyon, 2 miles from Bass Canyon. At 

Slate Creek, 8 miles southeast of Bass Canyon, 

and in the region southeast of Slate Creek (see 

Pl. XX) subdivision B is underlain by a series 

of gray vesicular magnesian limestones and 

interbedded sandstones which make a steep 

ledgy slope beneath the cliff of subdivision B. 

A section of these alternating limestones and 

sandstones at Hermit Creek is given on page 53. 

This series, which I have, assigned to the ~edwalllimestone (see p. 53), apparently occupies 

a lower horizon in the Redwall than subdivision C, which actually is probably a local bed 

atl the base of subdivision B. The alternating 

limestones and sandstones thicken southeastward, for they are 68 feet thick at Hermit Creek 

and at least 130 feet (estimated) at Red Canyon. I have not measured them at Slate, 

Pipe, and Cottonwood creeks. 
56 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

Thickness.-The Redwall limestone decreases in thickness in the 29 miles between 

Bass Canyon and ·Red Canyon. It is 570 feet 

thick at Bass Canyon, 538 feet at Hermit 

Creek~ and a little over 500 feet at Red Canyon. 

The decrease in thickness in the formation as 

a whole is not so great as the decrease in its 

cliff, because the series of alternating limestones 

and sandstones at the base of the formation 

increases in thickness southeastward as the 

overlying cliff-making limestone diminishes. 

At Kanab Creek, 30 miles northwest of Bass 

Canyon, the formation is a little over 700 feet 

thick. (See Pl. XIX.) 

Fossils.-Fossils are scarce in the Redwall 

limestone at the Bass, Herm.lt, and Bright 

Angel . trails. Commonly they are poorly 

preserved and are difficult to collect unless 

they are weathered out of the rock. In 1914 

I made small collections at two localities. · At 

Bass Canyon I obtained from the middle, 

distinctly bedded member (2) of subdivision 

B Fenestella sp. and Schuchertella chemungensis. This locality is at the Bass trail near the 

bottom of the narrow part of Bass Canyon in 

the Redwall. 

In the canyon of Hermit Creek I obtained 

from the same middle member of subdivision B 

Monilipora? sp. 

Crinoid stems. 

Fenestella, several sp; 

RhipidomEllla sp. 

Camarotoechia sp. 

Spirifer centronatus. 

Syringothyris? sp. 

The fossils were identified by G. H. Girty, 

who writes: 

Although these fossils are poor and constitute a very 

small fauna, they indicate with but little uncertainty a 

Mississippian (Madison) age and thus confirm previous 

·determinations of the age of the lower and major part of 

the Redwall limestone. It is true that an undoubted 

Pennsylvanian fauna has been cited by Meek from the 

upper part of the Redwalllimestone of this general region, 

but these fossils came from beds that are now being transferred to the Supai formation. 

In 1920 I collected fossils from beds near 

the top of the Redwalllimestone at two localities. 

One collection, which I labeled lot C, I 

obtained at the very top of the Redwall 

cliff in the canyon of Garden Creek directly 

under El Tovar. The locality is about an 

eighth of a mile east of the point where the 

Bright Angel (Cameron) trail descends the 

Redwall cliff an~ may be reached by leaving 

the trail at this point and walking eastward 

along the narrow bench at the summit of the 

cliff. The fossils weather from the upper 

surface of the limestone that underlies this. 

bench, and the horizon appears to be equivalent 

to the very top of subdivision B of .the B_ass. 

Canyon section. 

The other collection, which I labeled lot A, 

I obtained from bed 5 of subdivision A in 

Bass Canyon. (Seep. 31.) The locality is on 

the west side of Bass Canyon about a quarter 

of a mile north of the point where the Bass 

trail descends the break in the Redwall cliff 

at the head of the canyon. It may be reached 

by following the first bench above the top 

of the sheer cliff of subdivision B that is wide 

enough for a man to walk upon. The fossiliferous horizon is about 14 feet ~hove the top 

of the cliff. 

Regarding these -two collections Mr. Girty 

writes: 

Lot C contains an abundant fauna, though one showing 

but little diversity and represented by very unsatisfactory 

specimens. I ·recognize in it the following forms: 

Diphyphyllum? sp. (probably the same form shown 

by better specimen in lot A)'. 

Camarotoechia? n. sp. 

Spirifer centronatus. 

Spirifer aff. S. incertus .. 

Composita? sp. 

Bellerophon sp. 

Euomphalus? sp. 

Lot A contains Diphyphyllum (Lithostrotion?) sp., Camarotoechia? (apparently the same form as in lot C), and a 

fucoid. · 

These two lots contain essentially the same fauna and are 

of the same geologic age. As between Pennsylvanian and 

Mississippian, I should refer them with little question to 

the Mississippian. As between lower Mississippian and 

upper Mississippian-that is, as between Madison and 

Brazer-a definite conclusion can not . be reached. So 

few occurrences of upper Mississippian rocks are known 

in this southwestern region that a general probability is 

established that these faunas belong to the lower horizon. 

The facies of the faunas corresponds so far as it goes with 

the lower Mississippian faunas, as we know them now, but 

the forms contained in these collections are so few, so 

poorly represented, and in some cases so ambiguous that 

one can not deny the existence of a possibility that the 

geologic age may be upper Mississippian. To state the 

matter briefly, as I see it, the evidence so far as it goes 

suggests lower Mississippian, but it does not go far enough 

definitely to establish the lower Mississippian age of the 

horizon. My personal convictions, I may add, are strong 

that t~e age is actually lower Mississippian. 
PALEOZOIC FORMATIONS OF THE GRAND CANYON. 57 

Schuchert, who has collected fossils in ·the 

Red wall at the Hermit trail, states: 32 

Tll'e base of the Redwall on the Hermit trail consists of 

three thick beds. The · upper one is from 10 to 12 feet 

thick, and the, lowest bed is 8 feet thick, of a vesicular 

gray dolomite with the cavities filled with calcite. The 

upper bed ,has Syringopora cf. surcularia. Between these 

two dolomite beds is a yellowish-white sandstone, 4 feet 

thick.33 

The Redwall may be studied on the Hermit trail below 

the Cathedral Stairs, but the sequence can not be made 

-out with certainty because all of it has slumped and · slid 

-down in a huge landslide. The parts are mixed, and even 

some of the Supai is included with blocks of the Red wall. 

One entire day was devoted to collecting fossils from it, 

but the results were very unsatisfactory. Toward the 

miadle of the Redwall were seen sections of a few corals, 

-of Menophyllum and Clisiophyllum, and a number of crinoidal columnals, besides Spirijer centronatus. Of the few 

fossils taken away there is a Syringopora like S. 8urcularia 

Hirty, Menophyllum excavatum Girty, Fenestella and Poly-

-pora in several species, and a finely striate Spirijer. 

These fossils are seen to belong to the same fauna as those 

identified by Girty from near Nel!3Qn, Ariz., and _collected 

by W. T': Lee. The time indicated by them is that of the 

Madison limestone so widely distributed in the Rocky 

.Mountain country, or of the older half of the Mississippian of the Mississippi Valley. 

In 1879 Walcott collected fossil~· at Kanab 

Creek at many horizons in beds ' which he 

designated subdivisions ·b and c of the Redwall 

limestone. (See Pl. XIX.) These two subdivisions' and the underlying subdivision d of 

Walcott's section correspond closely in lithology 

with the Redwall of my Bass Canyon section 

.and constitute the Redwall as it is here redefined. Subdivision a, at the top .of Walcott's 

Redwall at Kanab Creek, corresponds in 

called the Madison limestone but which in New Mexico 

has received the name Lake Valley limestone. I do not 

myself .feel in doubt, although the evidence is not entirely 

conclusi e, that the entire Redwalllimestone, so far as it 

is embraced within the horizons represented by your 

collections A and C and by Mr. Walcott 's collections from 

Kanab Canyon, is of lower Mississippian age and belongs 

in a general alinement with the Madison limestone. 

The type locality of the Redwall limestone 

selected by Darton 34 is Red wall Canyon, in the 

Shinumo Amphitheater, only 4 miles north of 

Bass Canyon. The section at Bass Canyon, 

given in the present report, is so near _Redwall 

Canyon that it may be assumed practically to 

represent the formation at the type locality. 

The evidence just presented indicates that at 

the type locality the entire Redwall as here 

restricted is of lower Mississippian age, altliough 

it is conceivable, but highly improbable, as 

Girty · states, that th~ beds at the top of the 

formation in which I found fossils may be upper 

:Mississippian. 

No evidence has been found which indicates 

that any part of the Redwall as h~re recognized 

in the Kaibab division of the Grand Canyon is 

younger than Mississippian. 

Ransome/5 wbo has examined the Redwall 

in the Jerome region, where he collected fossils 

in it that Girty identified as lower Mississippian, states: "No evidence was obtained at 

Jerome to indicate that any of the Redwall 

limestone is as young as the Pennsylvanian." 

In the Jerome region the beds assigned to the 

Redwall aggregate only 250 feet and probably 

belong to the lower part of the formation. 

lithology to my subdivision C of the Supai PROBABLE UNCONFORMITY BETWEEN MISSISformation at Bass Canyon and undoubtedly SIPPIAN AND PENNSYLVANIAN SERIES. 

properly belongs in the Supai. (Seep. 62.) The top of the Redwalllimestone is very 

These collections from subdivisions b and c difficult to reach, except at places near the 

at Kanab Creek were never worked up in detail trails that descend the canyon wall, and I have 

by Walcott and in the course of time have be- so far been able to examine it only at the Bass 

Dome badly mixed with collections made from trail, at the trail which ascends the northern 

-other Carboniferous beds in the general region. wall of the Grand Canyon through Muav 

However, Mr. Girty, who has examined the Canyon, and at the Hermit, Bright Angel, and 

. material, makes the following statement con- Hance (Red Canyon) trails. Viewed .from a 

cerning as much of it as he is able to assign to distance it appears to exhibit no irregularity 

the collections from b and~: j at most places in the Kaibab division_ of the 

The faunas are much more extensive and conclusive . canyon. . 

than the one contained in your lots A and c, and I refer At Bass Canyon the contact between the 

them without hesitation to the lower Mississippian, to that typical bluish-gray limestone of the Redwall 

widespread limestone formation which has commonly been · 

~2 Schuchert, Charles, op. cit., pp. 360--361. 

as The three dolomite beds described by Schuchert are probably beds 

2, 4 t o 6, and 8 of my section at Cope l3utte given on page 53.-L. F. N. 

34 Darton, N. H., A. reconnaissance .of parts of northwestern New 

Mexico and northern Arizona: U. S. Geol. Survey Bull. 435, p. 21, 1910. 

35 Ransome, F. L.,· Some 'Pa!eozoic sections in Arizona and their 

correlation: U .- S. Geol. Survey Prof. Paper 98, p . 162, 1916. 
58 SHOR.TER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

and the red shale at the base of the overlying 

Supai appears to be remarkably even, and the 

only evidence of a stratigraphic break is the 

abrupt change from limestone to shale. However, actual exposures of the contact are not 

to be found, owing to the softness of ·the ~hale, 

which makes a slope at this horizon that is 

entirely c0ncealed by talus. 

At Muav Canyon the surface of the Redwall 

is uneven, but the beds are shattered along the 

axis of a faulted flexure, so that it is uncertain 

whether. the unevenness is due to shattering or 

to erosion. 

At the Hermit, Bright Angel (Cameron), and 

Hance trails the appearance of the top of the 

Red wall suggests that it was exposed to erosion 

before the overlying Supai beds were deposit< ... d, as I shall show. 

Near the Hermit trail, just south of the 

point where· the trail d~scends the Redwall, 

the upper surface of the Redwall limestone is 

decidedly uneven, and in places jagged knolls 

of the limestone project 25 feet or more above 

the general level of the surface. At this 

locality the basal deposit of the Supai is a 

bright reddish or purplish .sandy shale. Some 

pa:r:ts of the shale exhibit no bedded structure 

whatever; other parts exhibit gnarly, irregular 

bedding and are more or less concretionary, 

whereas still other parts are eveilly and thinly 

bedded. Thin lenses of conglomerate occur at 

some horizons In the shale. The pebbles in the 

.conglomerate are. well· r(·unded and are coated 

with black "desert uni~h." Most of them 

are composed of chPrt. derived, apparently, 

from the underlying limestone. The shale 

varies considerably in thickness from place to 

place. Above the tops of the higher limestone 

knolls the thickness may not exceed 45 feet, 

but between the knolls, where the deposit appears to fill depressions, the thickness may 

exceed 70 feet. The deposit becomes more 

evenly bedded toward the top, and the upper 

21 feet consists of thinly laminated. soft reddish shale. Above this shale are alternating 

·beds of red sandy shale, purplish and gray limestone containing red chert, and reddish to buff 

calcareous sandstone. ·The thickness of these 

alternating beds is 132 feet. The section just 

described, 202 teet in total thickness, is shown 

diagrammatically on Plate XIX. The beds 

are undoubtedly equivalent to subdivision C 

of the Supai at the Bass trail. (See p. 61.) 

The upper surface of the Redwalllimestone is 

infiltrated with red mud, and the overlying 

irregularly bedded, more or less structureless 

red shale appears to represent just such a deposit of red clay as one would expect to find 

above a weathered limestone surface. It is 

possible that the roughness of the top of the 

Redw~ll is due to shattering of the beds in this 

locality, because· the formation has slumped in a. 

landslide at the point where the ,trail descends 

it. For this reason the evidence just presented 

should be regarded as inconclusive. Nevertheless the lithologic change from the massive 

limestone of the Redwall to the structureless 

red deposit above it is so sharp that it indicates 

a stratigraphic break at this horizon, and the. 

variation in thickness of the red shale is also 

suggestive. The bed is 72 feet thick at the 

Hermit trail, whereas the shale at the corre .... 

sponding horizon in Bass Canyon is not over 14 

feet thick. (See p. 31; also Pl. XIX.) 

At the Bright Angel, (Cameron) trail the 

summit of the Redwall is irregular, but here 

also the evidence is inconclusive, because ·the 

Red wall is shattered by a fault in the· vicinity 

of the trail. 

·At Red Canyon the. sutnmit of the Redwall 

is well exposed near the 4,955-foot bench. 

mark, where the Hance trail descends the 

Redwall on the east side of the canyon. This. 

locality is some distance east of a fault that 

coincides with the axis of Red Canyon, so that 

the ·beds here have not been disturbed by the 

fault. Near the bench mark the surface of the 

Redwall is wavy, and the limestone is more orless infiltrated with red mud, but the best 

evidence of a stratigraphic break at the top of 

the limestone is found in the lithologic character of the overlying Supai beds. The Supai. 

begins abruptly with a bed of conglomerate,. 

which exhibits great variations in thickness. 

At one place it is 20 feet thick, at many places. 

5 to 10 feet thick, and at some places entirely 

absent. The conglomerate contains both angular and rounded pebbles of chert and lime...: 

stone, derived, apparently, from the underlyingRedwall. The pebbles range in diameter from 

a fraction of an inch to 6 inches but average 

about half an inch. The conglomerate is. 

gravelly and contains very little matrix. 

Where present the Ip.atrix consists of red sandy 

clay. Where the conglomerate is thickest it 

appears to fill shallow depressions in the Red-
PALEOZOIC FORMATIONS OF THE GRAND CANYON. 1 59 

wall. Above the conglomerate is 100 feet of 

red friable sandy shale that is more or less 

calcareous and in places exhibits concretionary 

structure, and above the shale are alternating 

beds of shale, limestone containmg red chert, 

and calcareous sandstone, some of which is 

cross-bedded. The conglomerate, red shale, 

and overlying alternating beds just described 

are "Undoubtedly equivalent to subdivision C 

of the Supai as exposed at the Hermit and 

'Bass trails. 

Walcott,36 in describing the upper part of the 

Redwall at Kanab Creek, states: 

Toward the close of the 700 feet of limestone and its 

intercalated cherty bands evidences of an approaching 

change occur. The horizontal bedding is broken by 

gradually increasing curves of depression and elevation 

of the previously level surface. The limestone becomes 

more and more interstratified with white chert, weathering 

black. Arenaceous layers of a detrital origin come in, with 

pink chert and chalcedony replacing the white chert of 

the beds beneath. ' 

Massive layers of brecciated chert in a quartzitic matrix 

denote the increasing chang~ of conditions, and soon the 

sandstone epoch of the Lower Aubrey group opens. The 

transition beds (a) have filled the hollows and leveled off 

the uneven surface of the limestone beneath, and, 255 feet 

above, the great sandstone group begins with a massive 

croRS-bedded sandstone stratup1 (e), 50 feet in thickness. 

The transition beds to which Walcott refers 

are the beds that constitute subdivision a of 

his Redwall at Kanab Creek (see Pl. XIX), 

which is now transferred to -the Supai (see p. 

-62). Therefore the uneven surface which he 

describes actually lies at the top of the Redwall 

limestone as here restricted, and the horizon 

occupied by the uneven surface is equivalent to 

that at the ::Uermit, Bright -Angel (Cameron), 

and Hance trails which Ihave just described. 

Schuchert,37 who has examined .the RedwallSupai contact on the Hermit trail, writes: 

The contact may be studied just beneath the signpost 

"Cathedral Stairs" that stands on Supai strata. It is of 

the disconformab~e type, and the Redwall is more or less 

· eroded. Where the contact was studied this limestonedolomite series terminates in thin-bedded deposits, with 

the beds varying in thickness from 12 to 20 inches. The 

Supai begins at once with its characteristic sandy and 

rain-pitted shales and muddy sandstones. This disconfor:ill.ity has far greater significance than the physical phenomena as seen on the Hermit trail would seem to indicate. 

36 Walcott, C. D., unpublished notes. 

a7 Schuchert, Charles, op. cit., p. 358. 

for the fossils of the Redwall are here all of eariy Mississippian age. Nothing of later Mississippian time is present, 

and the land interval preceding Supai deposition was cer~ 

tainly onger than all ~f Redwall time. 

Ransome 38 . reports that 8 miles north of 

Jero~e what he regards as the base of the 

Supai is a limestone conglomerate 2 to 3 feet 

thick, in which the pebbles are generally less 

than 12 inches in diameter. 'He states that 

l~yer ~f .a ~imilar congl~merate also occur a 

httle 1gher In the formatiOn. 

In brief, although the evidence just presente~ is inconclusive, it establishes a strong 

proba\bility that the upper limit of the Redwall 

is an unconformity of erosion. . I 

PENNSYLVANIAN AND PERMIAN ( ~) ROCKS. 

I SUPAI FORMATION (REDEFINED). 

Dejnition.-As originally defined by Dar- · 

ton 39 jthe name Supai formation was applied to 

abou1J 800 feet of red sandstones and shales, the 

latter! in part sandy, underlying _ the Coconino 

sand~stone, overlying the Redwall limestone, 

and omposing the lower part of the Aubrey 

grou in northern Arizona. ·Darton's Redwall 

limes one, like Gilbert's and Walcott's Redwall, ncluded rocks of Mississippian and Pennsylvanian age. IIi~ this report . the Supai forma tit is redefined by cutting off at the top· 

abou 300 feet of deep brick-red sandy shale 

and . ne-grained friable sandstone .of Permian 

age, o which the new name Hermit shale is 

hereirl applied, and by adding at the bottom 

abouJ 250 feet of red sandy 'shale, purplish and 

gray limestone with red chert, and reddish to 

buff lcareous sandstone of Pennsylvanian age 

that ~ave heretofore been included in the Redwalllrmestone. This redefin~tion of the Supai 

forma,tion has been adopted by the United. 

State Geological Survey. As thus defined the 

Supai formation is of Pennsylvanian and Permian ( ?) age and rests with probable unconformi y on the underlying Mississippian Redwall jlimestone. The accompanying . table 

shows the different classifications of the Carbonif~rous rocks of the Grand Canyon. 

38 Ran ome, F. L., op. cit., p. 162. 

39 Dart n, N. H., A reconnaissance of parts of northwestern New 

Mexico a d northern Arizona: U. S. Geol. Survey Bull. 435, pp. 25-21, 

l910. 
60 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

Classifications of the Carboniferous rocks of the Grand Canyon. 

G. K. Gilbert, 1875. 

(U. S. Geog. and Geol. Surveys W. 100th Mer. 

C. D. Walcott, 18RO. 

(Am. Jour. Sci., 

3d ser., vol. 20, pp. 221-225.) Rept., vol. 3, pp. 161-186, fig. 82.) 

Aubrey group. 

Redwall limestone group. 

Cherty limestone, 200- Upper Aubrey. 820 feet. 

Cross-bedded and other 

I 

sandstones, 300-1,000 

feet. 

1---------1 Lower Aubrey. 

Red and white shales 

and sandstones, 800 

feet. 

Alternating sandstones 

and compact limestones, 200-500 feet. 

Red wall limestone, 

sheer escarpment, 800 Redwall limefeet. stone. 

Limestones in lesser es- carpments and cal- careous shales, 800-

1,365 feet. 

Character of beds.-The Supai formatiOn as 

here redefined consists chiefly of sandstone but 

mcludes many beds of sandy shale and a few 

beds of limestone. Much of the sandstone is in 

thick, massive beds that make strong cliffs. 

The shales and beds of laminated sandstone 

make slopes. As seen from a distance, the distinctive features of the formation are its prevailingly red color and its steplike profile, which 

consists of a succession of cliffs · and slopes 

carved from the alternating hard and. soft beds. 

Close inspection shows that the red color of the 

formation is derived from the shales. The 

outcrops of the sandstones are stained reddish 

by ferritic pigment washed over them from the 

interbedded shales, .but the natural color of the 

sandstones, as shown on freshly · broken surfaces, is buff or pinkish buff. 

The sandstones of the Supai are uniformly 

fine grained. Some of them are regularly 

bedded and exhibit thin, platy lamination, but 

most· of them are conspicuously cross-bedded, 

and in the thicker layers the cross-bedded structure is on a coarse scale. In uniform fineness 

of grain and in coarseness of cross-bedding the 

more massive layers resemble the Coconino 

N.H. Darton, 1910. 

(U.S. Geol. Survey Bull. 435.) 

Kaibab limestone. 

Coconino sandstone. 

Supai formation. 

Redwall limestone. 

L. F. Noble, 1il22. ll 

(This report.) !I 

:: 

Age. 

,, 

Kaibab limestone. 

Coconino sandstone. Permian. 

Hermit shale. 

-Unconformity--··------------------------------· 

Supai formation (re- Permian (?)and 

defined). Pennsylvanian. 

-Unconformity (?)--1-..,.-------

Redwall limestone 

(restricted to Mis- Mississippian. sissi ppian limestones). 

sandstone. Commonly, however, their grains 

are bound together by calcareous cement, 

whereas the binding material in the Coconino is 

siliceous. Curiously, the prevailing dip of the 

inclined laminae in the cross-bedded sandstones 

of the Supai is south, just as it is in the Coconino. Most of the shale ·in the Supai resembles 

that of the overlying Hermit shale and is 

essentially a red sandy mud. Some beds exhibit sun cracks and ripple marks, but these 

features are not conspicuous at the Bass trail. 

Two types of limestone occur in the Supai. 

One type, which is clearly of detrital origin, 

consists of grains of calcareous sand, e~hibits 

faint cross-bedded structure on weathered surfaces, and in places passes into cross-bedded 

sandstone. Some beds of this type are crystalline, and others granular; most of them are 

pinkish buff. The other type of limestone is 

bluish or purplish gray, massive, and crystalline and contains nodules of red chert. Be& 

of this type occur only in the lower third of the 

Supai. Many of them resemble the limestone 

in the underlying Redwall. 

Subdivisions.-At Bass Canyon I have divided 

the Supai into three members, which in lithol-
PALEOZOIC' FORMATIONS OF THE GRAND CANYON. 61 

ogy and in topographic expression are sufli~ this sul division and the underlying Redwall 

ciently constant to be recognizable throughout limestot e. is described on pages 57-:-59, where 

the Kaibab division of the Grand Canyon. I have 1 resented evidence indicating that it is 

These members I have designated subdivisions a plane of unconformity by erosion. 

A, B, and C. . Subd1 vision B,· the middle member of the 

Near the top and just below the middle of the Supai, t 39 feet thick, begins at the base with 

Supai the cross-bedded sandstones are excep- heavy, cliff-making beds of buff cross-bedded 

tionally thick and massive and make strong, sandstf;e, 200 feet in aggregate thickness, 

conspicuous cliffs. Between these two sets of which re separated by thin layers of limestone 

cliffs and below them the strata make steep or red shale. These massive sandstones pass 

ledgy slopes. The strata that make the upper upwar . into alternating beds of red friable 

set of cliffs constitute subdivision A; those that shaly andstone and cross-bedded calcareous 

make the lower set of cliffs and the ledgy slope sandst9ne that ·contain thin interbedded layers 

above the cliffs constitute subdivision B; and of limestone and, 66 feet below the top of the 

those that make the slope at the base of the subdiv* ion, a promine~t bed ~f limestone 

Supai constitute subdivision C. conglomerate 28 feet thick. This conglomeSubdivision A consists chiefly of sandstone rate (s .e p. 30), which occurs in highly len ticbut includes a· few beds of sandy shale; sub- ular layers and consists chiefly of rounded pebdivision B consists chiefly of sandstone but bles of /limestone embedded in a matrix of red 

includes beds of sandy shale and a few beds of sandy rud, appears to be continuously tracelimestone; and subdivision C consists of sand- ·able nJ only through the Kaibab division of the. 

stone, shale, · and limestone in about equal canyo but far beyond. I have noted it on the 

proportions. Broadly, therefore, although the Bright Angel (Cameron) and Tanner trails, 

Supai consists chiefly of sandstone, it exhibits respect vely 18 and 32 miles southeast of Bass 

a passage upward from shale and limestone to Canyo1f, and in the Aubrey C~iff, near Seligman, 

sandstone. 70 miles southwest of Bass Canyon. At all 

.Subdivisions A and B rest on slightly wavy these ocalities the conglomerate occupies 

s1U'faces -at Bass Canyon. However, similar approx mately the same horizon in the Supai 

wavy surfaces occur at other horizons in the that it kloes at Bass Canyon. At the Bass trail 

Supai (see sections of subdivisions B and C, and th Bright Angel trail it rests on an uneven 

pp."29-31), and some of these surfaces aremore surface! which exhibits vertical irregularitie~ 

irregular than those at the base of subdi- , of sev1ral feet within horizontal distances of 

' visions A and B. Without further study it is 100 feet. It is conceivable that the conglomimpossi_ble to determi~e wh~th~r ~ny of them erate arks a ~tr ~tigraphic break in the Supai 

have widespread stratigraphic significance. that is more significant than. the contact beThe order; character, and thickness of the tween : ubdivisions A and B. 

strata that constitute the three subdivisions Nea~ Pine, in the Jerome region, Ransome 40 

just outlined are described in the section of the has noted a bed of limestone conglomerate in 

Supai giv.en on · pages 29-81, and the topo- what e regards as the . Supai at a hori_zon 

graphic profil~ of the beds is shown in the abou. t f.O feet abo~e tke base o~ the formatl~n. 

columnar sectwn, Plate XIX. The co glomerate Is 12 feet thiCk and overlies 

Subdivision C, at.the base of the Supai, 208 a sealllj of impure lignite. 

feet thick, begins at the bottom with alter- Subdivision A, at the top of the Supai, 806 

nating beds of red sandy shale and bluish-gray feet thick, begins at the base with massive beds 

limestone carrying nodules of red chert, and of pin, ish, purplish, or buff cross-bedded sandthe shales and limestones pass upward into stone-which form a set of cliffs nearly 200 feet 

alternating beds of red shale, bluish-gray in hei~ht. Above these sandstones are alterlimestone, and reddish to bu.ff calcareous sand- nating beds of soft red platy sandst_one and 

stone, a part of which is cross-bedded. The hard ff cross-bedded sandstone whiCh form 

limestones and harder sandstones form small a serie~ of cliffs and slopes. 

cliffs and the shales and softer sandstones At e top of subdivision A is a broad red . 

_form' slopes. Outcrops of mal?-y softer beds platform know:q. as the Esplanade, which begins 

are concealed· by talus. The contact between 4o Ranso e, F. L., op. cit., p. 160. 

91048°-23-5 
62 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

at Bass Canyon and extends far .westward in 

the int~rior of the Grand Canyon. I have 

described this platform in a previous report 41 

and have shown that, like every other ledge 

in the canyon wall, it is a · structural bench 

determined by the hardness of the beds that 

underlie it and the softness of the beds that 

overlie it, and that it does not necessarily, as 

Dutton supposed, 42 represent a temporary baselevel of erosion produced by a pause in the 

uplift of the region during the cutting of the 

Grand Canyon. West of Bass Canyon the 

Esplanade is so broad that it is by far the most 

striking feature in the canyon . landscape. 

East of ~ass Canyon it shrinks to a narrow 

ledge and is inconspicuous as a topographic 

feature but is nevertheless traceable continuously through the Kaibab division. Inasmuch as this bench is cut on the summit beds 

of the Supai it constitutes a landmark that 

enables the observer everywhere to distinguish 

the Supai formation from the overlying Hermit 

shale. In the region between Bass Canyon and 

the Hermit trail it marks a conspicuous unconformity between the Supai formation and the 

Rermit shale. (See pp. 63-64.) 

Fossils.-No determinable fossils have been 

found in the Supai formation in the Kaibab 

division of the Grand Canyon. The available 

evidence eoncerning its age may be summed 

up as follows: 

Subdivision a of Walcott's Redwall at Kanab 

Creek (see Pl. XIX), " arenaceous beds with 

pink chert passing down into shaly limestone, 

brecciated arenaceous cherty beds, and gray 

limestone with red chert," not only corresponds 

closely with subdivision C of the Supai as I 

have defined the formation at Bass Canyon 

but is. overlain at K~nab Creek by massive 

cross-bedded sandston~ (subdivision e of W alcott's "Lower Aubrey gr~up ") that corresponds to the massive sandstone at the base 

of subdivision B of the Supai at Bass Canyon 

and is underlain at Kanab Creek by massive 

limestone which is obviously equivalent to the 

upper part of the Redwall as defined at Bass 

Canyon. Therefore there can be no reasonable doubt that subdivision a of Walcott's 

Redwall is subdivision C of the Supai as here 

41 Noble, L. F., U.S. Geol. Survey Bull. 549, pp. 21, 73-75, 1914. 

42 Dutton, C. E., Tertiary history of the Grand Canyon district: U.S. 

Geol. Survey Mon. 2, p. 121, 1882. 

redefined. Su'bdivision a of Walcott's Redwall is division 5 of Gilbert's Paleozoic section 

at Kanab Creek, "purple and white arenaceous 

limes.tone with pink chert, in one bed passing 

into cross-bedded sandstone." Walcott 43 states 

that although at Kanab Creek he obtained no 

fossils from these beds nor from any part of the 

overlying sandstones, "the beds elsewhere have 

given evidence of their upper Carboniferous 

age by the presence of a fauna rich in many 

species." This fauna is the Pennsylvanian 

fauna described by Meek and listed by Gilbert, 44 

who says concerning it: "The fauna of the upper portion [of the Red wall] is rich in species 

and, while differing from that of the Aubrey 

limestone, is equally referable to the Coal Measures." By the" upper portion of the Red wall" 

Gilbert means not the upper portion of the 

Redwall as the formation is here restricted, 

but the beds that constitute division 5 of his 

section at Kanab Creek 45 and division 4 of his 

section at the mouth of the Grand Canyon, 45 

which are equivalent to the lower part of the 

Supai as here defined. Recently Longwell 46 

has found Pennsylvanian fossils in the Grand 

Wash Cliffs north of the mouth of the Grand 

Canyon "near the top of beds which apparently 

correspond to Noble's basal Supai in the Grand 

Canyon.'' 

The evidence just presented indicates that 

subdivision 0, at least, of the Supai is of 

Pennsylvanian age. The Supai is overlain by 

the Hermit shale, whichcontainsPermianfossils, 

and the two formations are separated by an 

unconformity of erosion, but inasmuch as no 

determinable fossils have been found in subdivisions A and B of the Supai there is no 

conclusive evidence that the unconformity 

separates Pennsylvanian and Permian beds. 

Therefore the Pennsylvanian-Permian contaet 

may lie at any horizon in the Supai between 

the· summit" of the ·formation and the base of 

subdivision B. However, no stratigraphic 

break as great as the unconformity at the base 

of the Hermit shale appears to occur within 

the Supai itself, so I am inclined to regard the 

entire Supai as probably of Pennsylvanian age. 

43 Walcott, C. D., unpublished notes. 

44 Gilbert, G. K., U.S. Geog. and Geol. Surveys W. 100th Mer. Rept., 

vol. 3, pt.1, p. 178, 1875. 

45 Idem, p. 162. 

46 Longwell, C. R., Geology of the Muddy Mountains, Nev., with s 

section to the Grand Wash Cliffs in western Arizona: Am. Jour. Sci., 

4th ser., vol. 50, p. 47, 1921. 
PALEOZOIC FORMATIONl OF THE I RAND CANYON. 63 

Robinson: .

47 has reported Pennsylvanian fosl cliffs to-~ ledge on the summit of the massive 

sils from the Red wall limestone at Elde~ sandstone that forms ' the main cliff of subdiviMountain, near Flagstaff. He states that a1} sion A. j When the observer has examined the 

this locality "the limestone becomes thinne~ unconfo mity in the fine exposure under Red 

bedded than usual and gives way to red calcaJ Top he will have no difficulty in following it 

reous shale and sandstone. The limestone -with his leye all around the rim of the canyon of 

immediately overlying these beds contains Hermit <Dreek, where it is in plain sight for sev-· 

many fragments of shale and includes at one eral mil . The unconformity marks the change· 

point . a patch of conglomerate." The fossils from the highest cliff-making strata·in the Supai_ 

determined as Pennsylvanian came "from thJ to the ofter, shaly beds that overlie them. 

uppermost strata" at this locality. In ~ It is di.fficult to recognize the unconformity atopinion, Robinson's description of the beds first sighlt because the beds above and below it 

indicates that they are equivalent to stratal are stag· ed the same color, a deep brick-red~ 

exposed in the basal part of the Supai in the Many fi e exposures of the unconformity may, 

Grand Canyon, . and not to any part of the however, be studied by following the trail that 

Redwall limestone as here restricted. I leads wdstward along the general level of the 

Lee 48 has also reported a Pennsylvanian Esplanal e from Red Top to Dripping Spring. 

fauna from · the top of the Redwall limeston, The ske chin figure 4, a, and the photograph 

in Truxton Canyon, near Y ampai. The fossils reprodu ed in Plate XXIV, A, show an exposare stated to have been obtained "near th~ ure of tHe unconformity on this trail at a point 

top of the exposed section." Probably the about a J quarter of a mile west of Red Top. 

limestone beds in which Lee found the Penn- As seen in the canyon of Hermit Creek the unsylvanian fossils. are also correlatives of lime- conformity is comparable in irregularity to the 

stones that lie in the basal part of the Supai at unconfo mity at the top of the Tonto (see pp. 

Bass Canyon. . I 49-51), ~hich indeed, it strongly resembles, the 

eroded s rface exhibiting in places irregulari- UNCONFORMITY BETWEEN SUPAI AND HERMIT 

FORMATIONS. ties of 5?·feet or more . . I disccrvered the unconformity in 1916 at the 

In Hermit Basin, 12 miles southeast of Bass end of a field trip when I came out of the canyon 

Canyon, a strong unconformity of erosion sepaJ over th~ He~mit trail, and ~ fur~ished Prof. 

rates the Supai formation as here redefined Schurhe~ With a sketch of 1 t whiCh he pubfrom the overlying red sandy shale here named lished in his paper on the Carboniferous formathe .Hermit shale. The unconformity is beau] tions oft e Grand Canyon in 1918.49 However, 

tifully exposed on the Hermit trail just under~ until192e I had no opportunity to examine the 

signpost marked" Red Top." (See Pl. XXIII, horizon 0f the unconformity at other localities, . 

B.) At this locality the top of subdivision A to learn komething of its extent, but in the fall 

of the Supai consists of alternating beds of of that } ear I was ·able to examine it at sevhard pinkish or buff cross-bedded sandstone eral poi ts in the south wall of the Grand Canand friable red platy sandstone. These beds1 

yon norttwest and southeast of Hermit Creek. 

make a succession of small cliffs and ledges justl[ Northwe t of Hermit Creek the unconformity 

under the bench that forms the floor of Hermit· is tracea le at least 11 miles, being plainly recBasin and locally represents the Esplanade ognizabl ! from the rim of the Grand Canyon in 

platform. Just under the "Red Top" sign aj the wall~ of Ruby Canyon, 2 miles southeast ~f 

sharp hollow 40 feet deep in these Sup,ai beds Bass Canyon. Figure 4, b, shows it just under 

is filled with the soft red sandy layers that con- Havasullai Point,. the end of. the promontory . 

stitute the Hermit shale. The soft Hermit that for s the west wall of the Ruby Canyon. 

shale in the hollow determines a break in the The sket h was drawn from the Grand Scenic 

small cliffs at the top of the Supai, and the trail Divide, J spur of the Esplanade a mile west. of 

takes advantage of this break to descend the Havasu~i Point, and· may be incorrect in de47 Robinson, H. H., Th~ San Franciscan volcanic field, Ariz.: u. s. tail, for I could not reach and examine the 

Geol. Survey Prof. Paper 76, pp. 21-22, 1913. locality s own by the sketch. At Bass Canyon 43 Lee, W. T., Geologic reconnaisance of a part of western Arizona: 

U. S. Geol. Survey Bull. 352, p. 15, 1908. . 49 Schucherl, Cha Ies, op. cit., p. 356. 
64 SHOR.TER CONTRJBUTIONS TO GENERAL GEOLOGY, 1922. 

I could not detect the unconformity, but the 

beds at its horizon are poorly exposed at that 

locality. 

At the Bright Angel (Cameron) trail, 5 miles 

southeast of Hermit Creek, the unconformity 

can be detected by very careful inspection, but 

the eroded surface exhibits so little relief that 

it would probably be unrecognizable to one 

who had not first examined it at the H ermit 

trail. At Tanner Canyon, 20 miles southeast 

of the Hermit trail, I could not detect it. In 

that region the Hermit shale is readily distinguishable from the underlying Supai formation 

both topographically and lithologically, but 

the contact with the Supai is so even that if it 

represents an unconformity of erosion the 

eroded surface is practically level. 

PERMIAN SERIES. 

HERMIT SHALE . • 

Definition.-At Hermit Basin above the unconformity just described there is a series of 

deep brick-red sandy shales and fine-grained 

friable sandstones whose thickness is 317 feet . 

measured from the base of the deepest depression and 267 feet measured from the summit 

of the highest knoll in the unconformity. 

(See Pl. XIX.) Formerly these strata were 

included in the Supai formation and were designated "shale of the Supai formation" or 

"Upper Supai shale," 50 but because they have 

been. found to be separated from the underlying beds by an unconformity, because they 

contain determinable fossils of Permian age, 

and because they ·are constant in 

--------~==~~i~llll iithology and are distinct from ~~-?-;_...< · Hermit shale the underlying beds in topo-

"'~~~~~iliiiillllllllllll7~~0~,~~~~:~i,~~~~~~ h' -ro·----~~~ 7.~ unconformity grap IC expression everywhere 

_;?' ·"" ,,.,,,, ·-: ··:' .. ··· , ... , in the Kaibab division, I have 

~~fiiil~l~;~~·~~~lfl,ll.fJilll fo",~at;on f~~P;:!,1~:~!~~ya~~ d:~g::t;,~ 0. has been adopted by the United 

States Geological Survey. The 

-~:;~:~;~~~~~iiiii. ii name is taken from Hermit Basin, Hermit shale where the beds are typically ex-

~ posed. The formation is conformt: ·::.=:i~~~···:·f~:: :r;-:£~:\ .. :·.-: -- -- -.·. · ._ .. ,.~ :;-;.;. .:-:~~-~~-: -:::~ ... ~·:.-.. ;-~i-~: ;·~-:.:~:l;~· .. ~~-:~:~:~ .. ~ .. \~ ~,.:-:. :{ .. ;:--:H:f;:·.:·:::;_. U nco nform i!Y ably over lai_n by the Coconino 

lli.!tlll'll;~~~--~~ 51~~~at;on =~~~::~r~l:;e t;;~~~!its:::e b in Tapeats Amphitheater, northFIGURE 4.-Diagrammatic sketches showing character of unconformity between Hermit west of Powell Plateau. . shale and Supai formation in Grand Canyon, Ariz. a, On trail between Red Top and A 

' Dripping Spring, Bright Angel quadrangle; b, under Havasupai Point, Shinumoquad- Character and thickness.- t rangle. . Bass Canyon the Hermit shale is 

In brief, although the. Supai formation is 1332 feet thick. The character and succession 

separated from the overlying Hermit shale by of the beds are given in the section on pages 

an unconformity of erosion which is con tin- 28-29 and their profile is shown in the columnar 

.uously traceable for at least 15 miles in the section, Plate XIX. The beds differ little 

Kaibab division, study of a wider area than I from one another in composition and conhave covered . will be necessary before it can sist essentially of sandy mud colored red 

be stated confidently that the unconformity is by ferritic pigment. ·The beds that I have 

a widespread feature in the Grand Canyon designated sandstone in the section are massive 

district. and relatively compact as contrasted with the 

In the area which I have covered the un- beds that I have designated shale, which are 

· -conformity coincides with the general level of thinly laminated, but the distinction between 

the Esplanade. If this association is signifi- sandstone and shale is unimportant. All the 

cant, the unconformity may extend over a strata are friable. Many beds exhibit sun 

very wide area, for the Esplanade extends cracks and rain prints, and. some beds are 

many miles west of the Kaibab division in the ripple-marked. One bed (No. 15, P· 29) conGrand Cany·on. oo Noble, L. F., op. cit., p. 69. 

,:• ... 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 131 PLATE XXIV 

A. UNCONFORMITY BETWEEN HERMIT SHALE AND SUPAI FORMATION ON TRAIL BETWEEN RED 

TOP AND DRIPPING SPRING, BRIGHT ANGEL QUADRANGLE, ARIZ. 

a, Kaibab limestone; b, Coconino sandstone; c, Hermit shale; d, Supai formation. 

B. TYPICAL EXPOSURE OF HERMIT SHALE IN TAPEATS AMPHITHEATER, NORTHEAST OF POWELL 

PLATEAU, KAiaAB QUADRANGLE. ARIZ. 

a, Kaioab limestone; b, Coconino sandstone; c, Hermit shale; d, e, f, subdivisions A, B, C of Supai formation. 

PROPERTY OF U. S. BU~r!'J 0~ MINES 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 131 PLATE XXV 

A. FOSSIL TRACKS ON SLAB OF COCONINO SANDSTONE AT HERMIT TRAIL, 

BRIGHT ANGEL QUADRANGLE, ARIZ. 

B. CEDAR MOUNT.AIN, VISHNU QUADRANGLE, ARIZ., FROM DESERT VIEW CAMP. 

a, Surface of Coconino Plateau; b, Shinarump conglomerate, capping Cedar Mountain; c, Moenkopi formation; d, Kaibab 

limestone. 
PALEOZOIC FORMATION OF THE GRAND CA~YON. 65 

sists of intraformational ·conglomerate. Near 

·the top of the formation many beds exhibit 

concretionary structure. Lithologically the 

Hermit shale r esembles many beds of sandy 

shale in the Supai, but unlike the Supai it 

contains no . massive hard layers of cros

bedded sandstone, and the more. sandy beds in 

the Hermit are prevailingly reddish, not buff, 

as they are in the Supai. Thin, platy lamination is the moE;;t prominent structural characteristic of the Hermit shale. Everwhere tHe 

formation makes a slope which is in strong 

topographic contrast with the sheer cliff of the 

overlying Coconino sandstone and with the 

steplike cliffs and ledges of the nnderlying 

Supai. 

Although the Hermit shale is constant in 

lithology throughout the Kaibab division of the 

Grand Canyon its thickness varies considerably. 

In the region about Tanner Canyon, in the eastern part of the Kaibab division, it is less than 

100 feet thick (estimated) and may be less than 

75 feet. At Bass Canyon it is. 332 feet thick, 

and west of Bass Canyon, at the west end of 

the Kaibab division, more than 500 feet . . T~e 

widening of the Esplanade west of Bass Canyon 

is caused, as I have shown,S1 by the increase in 

thickness of the soft Hermit shale, which 

wastes back from the floor of the platform, in 

conjunction with a corresponding shrinkage in 

the overlying hard Coconino sandstone, which 

defends the retreat of the wall above the platform. Apparently the Hermit shale continues 

to increase in thickness at least as far as KanJb 

' Cree~, for Walcott's subdivisions al, a2, and 

a3 of the Aubrey group at Kanab Creek, which 

I believe represent the Hermit shale, are 775 

feet in aggregate thickness. (See Pl. XIX.) 

Beds in Gilbert's section at the mouth of the 

Grand Canyon, 52 which he designates division 

3 and which may represent the Hermit sha~e, 

are said. to be 800 feet thick at that locality. 

In the Aubrey cliff 4 miles north of Selig~ 

man beds identical in lithology with . the typical Hermit shale underlie the Coconino sandstone and overlie a cliff -making portion of the 

Supai that corresponds in lithology and in 

stratigraphic position to subdivision A of the 

Supai as defined at Bass C~nyon. The beds 

between the Supai and Coconino formations 

are 80 feet thick, are soft a_nd thinly laminated, 

ol Noble, L. F., op. cit., p. 70. 

oz Gilbert, G. K., op. cit., p. 162. 

and make a slope above a bencH at the top of 

the Supai that corresponds to the Esplanade. 

Undoubtedly they are the Hermit shale. In 

this region the Coconino sandstone, although 

it is nearly 450 feet thick, does not make a cliff 

but weathers into a slope that is little steeper 

than that formed by the Hermit shale. The 

actual cliff-makers in the Aubrey cliff are the 

Supai formation and the Kaibab limestone. 

Describing the beds in the Jerome region 

that were believed to represent the Supai, 

Ransome 53 writes: 

At this locality [mouth of Sycamore Creek, 8 miles north 

of Jerome] the lower 700 feet of the Supai consists chiefly 

of fine-grained cross-bedded sandstone in beds less than 6 

feet thirk, with a smaller proportion. of deep-red shale. 

The general color is not brilliant, and some of.the sandstone beds incline to a tawny hue. The upper beds of this 

division of the formation are fairly massive and form an 

outer bench in the plateau escarpment at this locality. 

Overlying them and under the Coconino sandstone are 

apparent1y softer beds of much brighter red, with an esti-. 

mated thickness of 200 to 300 feet. As seen through field 

g1asses at a dista,nce .of 2 or 3 miles they show conspicuous. 

cross-bedding and appear to grade upward with no sharp 

break into the Coconino sandstone. 

Perhaps the soft beds noted by Ransome 

·beneath the Coconino . sandstone and the rock 

bench formed by the Supai are the Hermit 

shale. 

Fossils~--Schuchert was the first geologist 

to find fossils in the Hermit shale. He states: 54 

Just below the sign " Red Top'' in the lower turn of the 

Hermit trail [in Hermit Basin] and immediately above 

the thick upper sandstone [of the Supai] are seen tbjn. 

bedded red shaly sandstones alternating with deep-red 

zones of shale. The surfaces of the glistening and smooth 

platy sandstones are replete with :fillings of the small 

prisms of interbedded sun-cracked shales, are often rainpitted, and further marked by the feet impressions of 

fresh-water amphibians described elsewhere in this number of the Journal by Prof. Lull 55 as Megapezia? coloradensis and Exocampe? delicatula. Some of the 'tracks are 

distinct impressions of the feet, and others are mere strokes 

of the toes. In these same beds also occur plant remains 

· in very fragmentary condition which were badly macerated and coated with a slime of red mud during their 

entombment. They are therefore difficult to determin~, 

but after much effort Dr. David White tentatively identified · them as Gallipteris sp. cf. C. conferta, Walchia cf. 

W. gracilis, Gigantopteris, and cf. Sphenophyllnm. * * * 

The plants listed above and found associated with the 

tracks led White in his letter to the writer dated June 27; 

1916, to the following conclusions: "The condition of 

preservation of the fragments is so bad that caution is 

53 Ransome, F. L., op. cit., p.l62. 

64 Schuchert, Charles, op. cit., pp. 353-354. 

oo Lull, R. s., Fossil .footprints from the Grand Canyon of the Colorado: 

Jour. Am. Sci., vol. 45, pp. 337-346, May, 1918. 
66 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

necessary in basing conclusions of any kind on the material 

submitted. However, the presence of Gigantopteris, 

Walchia, and probably of Callipteris, if my tentative 

generic identification of the latter is correct, points to 

lower Permian age of the flora. * * * In any event, 

it appears probable that the flora, when it is better known, 

will be found to indicate' a level not below the highest 

stage of the Pennsylvanian." 

In 1916 I made a small collection of plant 

material from beds at the base of the Hermit 

shale resting in depressions in the unconformity 

near Red Top in Hermit Basin. The collection 

was examined by Mr. White, who made the 

following report: 

The fossils are very obscure on account of the maceration 

of the plant substance, the washing of the surface with 

mud slimes, with more or less curling, and deformation 

produced apparently by shrinkage in the sun, so that the 

nervation is in general obliterated, even the midribs 

being imperfectly represented in some cases. Curling of 

the leaves obscures or even conceals their true forms. 

One· of the _specimens probably belongs to the genus 

Pecopteris. Two other fragments may represent a species 

of .Alethopteris. Another fragment has the outline of 

Callipteris. If the outline is not misleading as the result 

of shrinkage and curling of the borders of the leaf, the 

plant probably is a Callipteris, in which case the evidence 

'Jf the fossils will conform to the tentative age determinations based upon the collection submitted by Prof. Schuchert, namely-, that the beds are Permian in age, or possibly 

referable to the latest Pennsylvanjan. 

Pending the collection of additional material, some of 

which it is hoped will be found better preserved, the reference of the extremely obscure and imperfect fragments to 

the Permian must be considered as provisional. I anticipate, however, that more material will point more strongly 

to the Permian ~ge of the upper part of the Supai formation . . Should this prove to be the case, the unconformity 

at the base of the Permian in northern Arizona will remind 

geologists of the strong angular conformity beneath the 

Permian.'' Red Beds" on 'the south flank of the Ouachita 

Mountains in southern Oklahoma and the presence of inconspicuous conglomerate in or near the base of the Permian in northern Oklahoma and southern Kansas. 

In 1920 I returned to Hermit Basin and 

searched the Hermit shale in the hope of getting material that would prove to be specifically determinable, and at a point 50 feet 

above the base of the formation, a quarter of a 

mile west of Red Top on the trail to Dripping 

Spring, at the locality shown in the sketch and 

photograph (fig. 4, a, and Pl. XXIV, A), I obtained among other specimens a well-preserved 

part of a fernlike frond, concerning which Mr. 

White writes: 56 

A close inspection shows it to belong to the genus· Callipteris, which the world over is everywhere recognized as 

66 White, David, personal letter. 

the most characteristic and widespread exclusively Permian fern. I judge that the specimen is not even varietally distinguishable from Callipteris conferta. Accordmgly this evidence practically confirms conclusively the 

opinions based on fragments previously collected by you 

and Prof. Schuchert and is of itself probably adequate 

to prove the Permian age of the Hermit shale. Taken 

in connection with the plant fragments previously transmitted by Prof. Schuchert and you, it can be only 

Permian. 

In 1920 I noted imperfect fragments of plant 

impressions here and there in the Hermit shale 

near the Bass trail and near the Bright Angel 

trail. The fragments are not confined to any 

particular bed in the formation but occur at 

various horizons. They are not nearly so 

abundant as they are at Hermit Basin. 

In the light of the evidence just presented 

the Hermit shale may be confidently assigned 

to the Permian. 

COCONINO SANDSTONE. 

Oharacter.-The Coconino sandstone' is a 

pale-buff fine-grained cross-bedded sandstone 

whose distinctiye features are its massive appearance, the huge scale of the cross-bedding, 

and the uniform fineness of' the component 

grains of sand. The massiveness of the sandstone, which is due "to the coarseness of the 

cross-bedding, causes it to weather into the 

highest and most precipitous cliff in the upper 

wall of the canyon. 

The formation is made up of lenticular beds, 

each of which is truncated by the bed above it 

in such a way that, as outlined in cross section 

or cliff faces, the beds commonly form irregular wedges whose sides are sweeping curves. 

Each wedge consists of innumerable thin inclined laminae. Horizontal bedding is absent 

except near the base of the formation, where 

it is inconspicuous. The wedges differ greatly 

in thickness. One wedge, near the Bass trail, 

is more than 75 feet thick; most are between 

10 and 75 feet; some are less than 10 feet. In 

every wedge the laminae dip in a general 

southerly direction ranging from southeast to 

southwest, but the dip is not uniform in all 

parts of the wedge. The laminae form parallel 

curves that flatten downward. Cm;nmonly at 

the top of a wedge they are inclined .at angles 

of 15° to 25°, or exceptionally 30°, but near 

the base . of a wedge they bend and become 

horizontal or nearly horizontal. The prevailing dip of the laminae is south wherever the 

Coconino sandstone is exposed in northern 
' PALEOZOIC FOR.MATIO:NS OF THE GRAND CANYON. 67 

Arizona. This feature causes the formatibn 

to make a more continuous cliff in the s'outhern 

wall of the Grand Canyon than it does in th~ 

northern wall, because where the outcropping 

edges of the sandstone face south, as they p.o 

in the: northern wall, the sandstone breaks 

down here and there into slopes on the dip I of 

the laminae. A break of this character permits the Hermit trail to descend the sandst9ne 

in Hermit Basin, and another permits the Bass 

trail to descend it near Bass Camp. At b1th 

places the Coconino cliff faces southwest in 1an 

alcove cut at right angles to the prevailing 4ip 

of the beds. I 

The sandstone is cut by many vertical joints. 

In weathering, it splits into blocks along thes~ 

joints or into slabs ~long the inclined lami ae 

rather than along contacts between the wedgrs. 

Although the prevailing color of the sandstone 

is pale buff, some wedges are rusty buff, pinkish, 

or pale red. The reddish color, where preseht, 

is strongest, as a rule, at the base of a wedge. 

The constituent grains of the Coconino sandstone are quartz, ,and they are bound togetHer 

by siliceous cement; the rock does not effervesce with acid. Commonly the grains are 

uniformly small, translucent to transpareft, 

and rudely globular or subangular ratlier 

than broken or angular, but fresh surfaces I of 

the rock feel gritty and sparkle in the sunlight. 

Exceptionally the grains are rather coarse, re well rounded, and are dull on the surface, like 

ground glass. These dull, rounded grafus 

commonly form thin bands or streaks. 1 

Ripple-marked or sun-cracked surfaces re 

very rarely seen in the Coconino sandstone. I I 

have never seen ripple marks in it, but Se~uchert57 has noted them at one place, near the 

Hermit trail. Near the Bass trail the under 

surface of the .formation contains distinct impressions of sun ·cracks, but these impressio1

ns 

are derived from the upper surface of tpe 

underlying Hermit shale. The only sun cracks 

I have noted that ate unmistakably within the 

Coconino itself are on· a block in a talus sl* e 

near the Hermit trail. · I · 

At the Bass, Hermit, and Tanner trails the 

sandstone at the base of the Coconino is jin 

horizontal layers for 5· to 25 feet above the 

Coconino-Hermit contact, and some of , th se 

layers do not exhibit cross-bedding. At tre 

Tanner trail these horizontal beds of sandsto le 

sr Schuchert, Charles, op. cit., p. 349. 

alternate with layers of red shale, so that the 

boundary between the Hermit shale and Coconino sandstone is not sharp. At the Bright 

Angel (Cameron) trail the cross-bedding 

begins abruptly at the base of the Coconino. 

·At the Hermit and ·Bright Angel trails the 

beds at the top of the Hermit shale are cut 

here and there by vertical fissures that do not . 

extend upward into the Coconino sandstone. 

These fissures, some of which extend downward 15 to 20 feet into the Hermit shale and 

are 6 inches to a foot wide at the top, ar~ filled 

with the huff sand that constitutes the overlying Coconino sandstone. Probably they are a 

wid~spread feature of the Coconino-Hermit 

contact, for a few of them are exposed under 

F<;>ssil Mountain, near Havasupai Point, 11 

miles from the Hermit trail. I have not 

seen them at Red Canyon or at Tanner Canyon, 

hut the contact is poorly exposed .at those 

localities. 

The Coconino-Hermit contact is the most 

favorable horizon for springs in the upper part 

of the canyon wall, because the upper surface of 

the relatively impervious Hermit shale checks 

the downward movement of ground water percolating th:r:ough the more . pervious Coconino 

sandstone. Many small springs issue at this 

contact in the I{aibab division of the canyon. 

Dripping Spring, 'at Hermit Basin, and a 

spring at the Muav Saddle, near the head of 

Muav Canyon, are examples. 

Thickness.-In the region between Kanab 

_Creek and the east end of the Kaihah division 

the thickness of the Coconino sandstone increases st'eadily southeastward and is everywhere in inverse ratio to that of the underlying 

Hermit shale. For example, the Coconino is 

only 30 feet thick at Kanab Creek (see section . 

by Walcott, Pl. XIX), where beds believed to 

represent the Hermit shale are 775 feet thick; 

250 feet thick at the west end of the Kaihah 

division, where the Hermit shale is 550 feet; 

330 feet at the Bass trail, where the Hermit 

shale is 332 feet; 350 feet at the Hermit trail, 

where the Hermit shale is 267 to 317 feet; 550 

feet (estimated) at Red Canyon, where the 

Hermit shale is 130 feet (estimated); and 550 

to 650 feet in the eastern end of the Kaihah 

division, between the Tanner trail and the Little Colorado, where the Hermit shale is 75 to 

100 feet. The height of the Coconino cliff as. 

seen from Desert View near the TannJr 'trail is 
68 ' SHORTER CONTRIBUTIONS TO GENER.AL GEOLOGY, 19·22. 

thus ~lmost double the height of the cliff as 

seen from the head of the Hermit trail or from 

Bass Camp. 

Fossils.-The only traces of life that have 

been found in the Coconino sandstone are fossil 

footprints of small animals. The locality is on 

the H~rmit trail between 140 and 200 feet 

above the base of the sandstone and is easily 

accessible. The tracks occur on the upper surfaces of inclined laminae of th~ sandstone that 

dip 15°-25° SW., and they are found over a 

considerable area between the elevations stated. 

The beds that contain the tracks have a slightly 

darker color than most of the Coconino sandstone exposed on the trail, weathering a rusty 

buff. The tracks are hard to recognize at first, 

as they are small, like those of a squirrel or a 

small cat, and the impressions are faint, but 

the tracks are abundant, and the observer will 

see a great many of them after he has become 

familiar with their appearance. Most of them 

appear to have been made by animals walking 

up the slope of the inclined laminae. A large 

number will be found in place on the outcropping inclined surfaces of the sandstone, but 

many loose slabs of rock scattered about the 

trail contain good impressions. The photograph reproduced in Plate XXV, A, shows impressions on one of these slabs. Specimens of 

two kinds of tracks collected by Prof. Schuchert 

in 1915 and by me in 1916 have been described 

by Lull 58 as Laoporus schucherti and Laoporus 

noblei. He regards the animals that made 

them as ancestral amphibia. He states: 

The creatures which made the footprints were quadrupeds of moderate size, with broad, stumpy feet, apparently clawed, and having at least four toes in front and 

five behind. The hind foot, which is somewhat the larger, 

b~re a proportionately greater share of the creature's 

weight, especially in the smaller species. The limbs 

were apparently short, with a wide trackway, implying 

a bulky body. No trace of a dragging trail is discernible on 

any of the specimens, and the body was evidently carried 

clear of the ground. Several known genera of Paleozoic 

footprints may be compared with the present species, but 

none agrees with sufficient closeness to warrant the inclusion of these forms. They therefore seem to pertain to 

a new genus, which will be called Lao porus and the affinities of which, from the criteria which they present, seem 

to lie with the genus-Limnopus Marsh, from the Kansas 

Coal Measures. 

Probably the specimens described do not 

represent all kinds of tracks obtainable at this 

locality, for in examining the locality more 

58 Lull, R. S., op. cit., pp. 338-341. 

carefully· in 1920 I noted tracks that differ 

froin those already described. 

In origin I believe the Coconino sandstone is 

essentially a dune deposit, because it resembles in many structural and lithologic features 

parts of younger formations exposed : in the 

Navajo country, notably the DeChelly, .Navajo, 

and Wingate sandstones, which, as Gregory 59 

has shown, are almost certainly dune deposits. 

Thin sections cut from specimens of the Coconino sandstone that I have collected for study 

may throw more light on the origin of the sand. 

This material, however, which also includes 

thin sections cut from beds in other Paleozoic 

formations of the Grand Canyon, has no.t yet 

been studied, and I will reserve a discussion of 

it for another report. 

KAIBAB LIMESTONE. 

Oharacter.-The Kaibab limestone forms the 

surfa e of Coconino and Kaibab plateaus, which 

border the Grand Canyon, and makes the first 

cliffs that drop away at the rim of the canyon. 

It is composed of limestone and sandstone and 

at some horizons contains large amounts of 

chert. Fragments of chert weathered from 

the formation are abundant nearly everywhere 

on the surface of the plateaus. The beds of 

limestone are hard and make cliffs in the canyon 

wall; the sandstones are soft and make slopes. 

Relatively the Kaibab is not a heavily bedded 

formation, like the Redwall. Some. limestone 

beds are over 6 feet thick, but many are from a 

few inches to 5 feet thick. The bedding planes 

are distinct throughout the formation. The 

prevailing colors of th~ limestones and of most 

of the sandstones are buff, cream, or gray, 

but some of the sandstones, notably in the 

middle ·part of the formation, are red or yellow. The limestones in the upper part of the 

formation are the most fossiliferous rocks in the 

Grand Canyon, some beds being composed almost .entirely of the remains of sea animals, 

chi~fly bryozoans, sponges, brachiopods, and 

gastropods. Fossil Mountain, a dissected promontory of the Coconino Plateau near Bass Camp, 

is carved from these fossiliferous beds and is s.o 

named because the fossils, weathered from .the 

limestone, litter its southwest slope. 

At Bass Canyon the Kaibab limestone i& 

divisible into three members which in lithology 

and in topographic expression are distinct from 

59 Gregory, li. E., Geology of the Navajo country: U.S. Geol. Survey 

Prof. Paper 93~ pp. 31-34, 53-55, 57-59, 1917. 
PALEOZOIC FOR.MATIONS OF THE GRAND CANYON. 69 

one another everywhere in the Kaibai> division. 

Subdivision A, at the top of the formation, 292 

feet thick, consists of gray crystalline limestone 

which passes at the base and top into alternating beds of fine-grained sandstone and very 

cherty limestone. Subdivision B, in the middle 

_ of _ the formation, 136 feet thick, consists of 

more or less irregularly bedded buff, yellow, 

and red fine-grained sandstone and contains 

beds of sandy breccia. Subdivision C, at the 

base of the formation, 134 feet thick, consists 

of alternating beds of buff sandstone and limestone which pass up into a very massive bed of 

siliceous limestone. Subdivision A forms cliffs 

and steep slopes, B forms a slope, and C forms 

a succession of cliffs and slopes. The order, 

character, and succession of the beds that constitute these subdivisions are described in the 

section on pages 27-28, and the profile of the 

subdivisions is shown in the columnar section, 

Plate XIX. 

Two analyses of limestone in subdivision A 

follow. One analysis shows the composition of 

a sample taken from a bed (No. 2, p. 27) just 

under the rim of the canyon at the Bass trail. 

This limestone is associated with the sandy 

beds in th~ upper part of the subdivision. It is 

dense but not crystalline, feels dull or earthy 

when struck by the hammer, and in appearance 

suggests silicified chal~. Similar beds higher 

in the Kaibab limestone are exposed on tp_e 

Coconino Plateau east of Bass Camp but are 

· not included in ;my section. 

This rock is an impure dolomite. The second 

analysis shows the composition of the limestone 

that forms the greater part of the subdivision. 

This limestone is hard, gray, more or less cherty, 

very fossiliferous, and entirely crystalline. The 

sample analyzed was taken from bed No. 6 

at the Bass trail. (See p. 27.) The analysis 

shows that this limestone is not magnesian, 

although it is relatively impure. Probably the 

insoluble impurities are largely the silica that 

forms nodules of chert associated with the limestone; for the ·rock represented by the sample_ 

analyzed contains no detrital sand. 

Partial chemical analyses of limestone from subd1~vis~on A, 

Kaibab limestone. 

[Alfred A. Chambers, analyst.] 

Insoluble ................ . ........ . (Al, Fe)20 3 •••••••••••••••••• • •••• : 

CaO .• -.-........•••••..•• · .....•.•.• 

MgO .. · •.....••• · .•...•••••.•.•.... 

6.98 

. 56 

29.98 

18. 68 

2 

11.15 

.71 

48. 68 

.00 

The sandstones of subdivision B consist entirely of quartzose sand which in composition, 

fineness, and uniformity of grain resembles the 

sand in the Coconino sandstone. ·Much of the 

sandstone is loosely consolidated and crumbles 

to sand when struck with the hammer. The 

cement appears _ to be siliceous, for the rock 

does not effervesce with acid. Some beds are 

evenly laminated; others exhibit curious gnarly 

structure like that in parts of the Devonian 

Temple Butte limestone (p. 51). Wavy, irregular surfaces separate many beds. A bed of 

brecciated sandstone occurs at the top of the 

subdivision at Bass Canyon, and a similar bed 

occurs near the middle. (Seep. 27.) It is difficult to determine from the exposures at this 

·locality whether · the · br~cciated structure is 

detrital in origin, the fragments representing 

boulders in a conglomerate, or whether the 

structure 'fas acquired after the beds were 

consolidated, the beds caving in and breaking 

because some soluble mineral, perhaps gypsum, 

was· leached out of them. The sandstones of 

the subdivision contain no gypsum at the Bass 

trail, but equivalent beds at Kanab Creek described by Walcott (see Pl. XIX) contain gypsum, as also .do equivalent beds at Cataract 

Creek described by Newberry.6° Cataract Creek 

is about 20 miles southwest of Bass Canyon. 

The prevailing reddish and yellowish hues 

of the sandstones that constitute subdivision B 

contrast strikingly with the pale buffs and grays 

of the strata in the overlying and underlying 

subdivisions of the Kaibab and enable the 

observer readily to distinguish the subdivis~on. 

In general appearance the limestone . in the 

massive cliff-making bed at the top of subdivision C (see p. is) resembles that in the 

bed at the top of subdivision A, whose composition is shown by the analysis 'on this page 

to be near that of dolomite. Probably the rock 

is a siliceous dolomitic limestone. The sandstones that alternate with the limestones 

below this bed do not appear to differ con- · 

spicuously in composition from those in 

subdivision B, but all of them are evenly 

bedded, and some exhibit shaly lamination. 

The contact between subdivision C and the 

underlying Coconino sandstone is level and 

even, and the bottom bed of the subdivision, 

&o Newberry, J. S., Report upon the Colorado River of the Westr 

explored in 1857-58 by Lieut. J. C. Ives, pt. 3, Geological report, 1861. 
70 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

a fine-gr~ined reddish to yellowish sandstone, 

rests ~verywhere on the truncated edges of 

inclined laminae of the Coconino sandstone. 

Thickness.-The Kaibab limestone is 562 

feet thick at the Bass trail and about 25 feet 

thicker a short distance east of the trail, but 

inasmuch as the summit of the formation is 

the eroded- surface of the Coconino Plateau, 

the original thickness can not be determined. 

In fact, the only place where it can be determined in the Kaibab division is in the area 

between the rim of the Grand Canyon and 

Cedar Mountain, -35 miles southeast of Bass 

Canyon. At Cedar Mountain, 2 miles from 

the rim of the canyon, the Kaibab is overlain 

by younger beds that have not been removed 

by erosion, and the top of the Kaibab is 

exposed benea~h these beds at the southern 

base of the mountain. As shown on page 72 

certain beds at the top of the Kaibab at the 

base of the mountairi can be identified with 

beds exposed at the· top of the Kaibab at the 

rim of the canyon 2 miles away. Therefore 

the original thickness of the Kaibab can be 

obtained by measuring the formation in the _ 

canyon wall .at this point and adding the 

thickness of Kaibab beds exposed under 

Cedar Mountain that have been removed at 

the rim of the canyon. These measurements 

have not been made. 

Although the three subdivisions of the 

Kaibab limestone are · everywhere readily 

distinguishable from one another they exhibit 

variations in thickness a.nd lithology as they 

are traced southeastward through the Kaibab 

division from Bass Canyon. At Red Canyon, 

on the Hance trail, 30 miles southeast of Bass 

Canyon, subdivision C, at the base of the 

formation, is 75 feet thick, whereas at Bass 

Canyon it is 134 feet thick. The cliff-making bed of buff limestone at the top of the 

subdivision is about equally thick at both 

localities, but the alternating sandstones and 

limestones between . this bed and the Coconino sandstone have shrunk from 86 feet 

at Bass Canyon to 30 feet at Red Canyon. 

Subdivision B is 143 feet thick at Red 

Canyon, practically of the sam.e thickness as 

at Bass Canyon, and the component beds of 

sandstone differ very little at the two localities. 

The subdivision contains brecciated sandstone 

at Red Canyon, as it does at Bass Canyon, 

but. at Red Canyon the brecciated sandstone 

occupies a horizon near the middle of the subdivision, whereas. at Bass Canyon it occurs 

at both the middle and the top. At Red Canyon the brecciated sandstone forms a bed 15 

feet thick and consists of angular fragments 

of red and bu.ff sandstone as much as 4 feet in 

diameter embedded in a matrix of gnarled 

and twisted sandstone. At this locality the 

brecciated sandstone appears to represent a 

conglomerate, not a bed shattered after deposition and consolidation. Undoubtedly these 

brecciated beds are a constant feature of 

subdivision B, for I have seen them at all 

localities where I have examined the subdivision between Bass Canyon and Red Canyon. 

One of these beds is exposed on the Hermit 

trail. · 

Subdivision A is 355 feet thick at Red 

Canyon and 292 feet thick at Bass Canyon, but 

the summit is eroded at both places, so that 

the differences in thickness may not be significant. At Red Canyon, as at Bass Canyon, 

chert is less abundant in the middle of the subdivision than near the base and top and is 

most abundant near the top. The limestone 

in the subdivision at Red. Canyon, however, is 

not nearly so pure as it is at Bass Canyon, is 

not prevailingly crystalline, and most beds are 

earthy, sandy, or siliceous, resembling the buff 

magnesian limestone at the top of the Bass 

Canyon section rather than the gray crystalline 

limestone that constitutes th~ greater part of 

the subdivision at Bass Canyon. Thus subdivision A as a whole becomes sandier and more 

siliceous southeastward from Bass Canyon. 

The limestones are decidedly more sandy at 

the Hermit trail than they are at the Bass 

trail and more sandy at Red Canyon than they 

are at the Hermit trail. 

Fossils.-Fossils are very abundant at many 

horizons in subdivision A. At Bass Canyon 

they are most abundant in the beds of gray 

crystalline limestone designated 5 and 6 in 

my section (p. 27). The following list of a 

collection in the possession of G. H. Girty 

obtained at Parusi-Wompats Spring, just north 

of ·the Shinumo region, includes most of the 

forms that occur ne~r Bass Canyon: 61 

Sponges. 

Lophophyllum n. sp. _ 

Crinoid stems. 

Fistulipora sp. 

16 Noble, L. F., op. cit., p. 71. 
PALEOZOip FOR.MATIONS OF. THE GRAND . OANYON; ~ . 71 

Meekopora sp. 

Stenopora sp. 

Septopora sp. 

· Polypora sp. 

Lingulidiscina convexa? 

Derbyasp. 

Meekella pyramidalis. 

Chonetes aff. C. hillianus. 

Producus occidentalis. 

Productus ivesii. 

Productus aff. P. irginae. 

Productus subhorridus var. rugatulus. 

Productus sp. 

Pugnax osagensis var; 

Heterelasma n. sp. 

Squamularia guadalupensis? 

Spiriferina campestris? 

Composita subtilita. 

A viculipecten, 2 sp. 

Acanthopecten occidentalis. 

Pseudomonotis aff. P. hawni. 

Pseudomonotis? sp. 

Anisopyge perannulata? 

These and other fossils constitute the soealled Productus ivesii fauna. Girty regards 

this fauna as Permian and tentatively c~rrelates the Kaibab limestone with the !San 

Andres limestone in the Manzano grou ]> of 

New Mexico. . I 

No fossils have been found in subdivi ion 

_B, the sandstone member of the Kaibab, but 

.a few occur in subdivision C. · So far as I ow, 

no fossils have been collected and descr bed 

from these two lower subdivisions of · the 

Kaibab limestone in the Grand Canyon, -and 

it is therefore conceivable that the lower art 

of the formation may contain a fauna diffe ing 

. somewhat from that in the upper part. owever, Newberry's section at Cataract Ore k 62 

mentions Producttls ivesii in beds equivale t to 

those at the base of subdivision C. Inas uch 

.as the Hermit shale beneath the Kaibab 1 ontains Permian plant remains, no part of the 

.Kaibab can be older than Permian. 

BEDS OVERLYING THE KAIBAB LIMESTON AT 

CEDAR MOUNTAIN. 

No beds younger than the Kaibab limes one 

are exposed in the wall of the Grand Canyo in 

the Kaibab division, but Cedar MountaTir-, a 

:flat-topped butte on the Coconino Plateau ~nly 

2 miles east of the rim of the canyon. 'ear 

Desert View Camp, is carved from you~ger 

beds. These beds at Cedar Mountain constitute two formations-the Shinarump c-onglbm62 NewberiJ:', J. S., op. cit. 

erate, 25 feet thick, which makes a cliff encircling the top of the mountain and determines 

its fiat summit, and the Moenkopi formation, 

481 feet thick, which makes the slopes of the 

mountain. _The age of_ these two formations is 

Mesozoic, the Moenkopi being regarded as 

Lower Triassic and the Shinarump as probably 

Upper Triassic. The Moenkopi formation, 

which is relatively soft, owes its preservation to 

the hard Shinarump conglomerate that caps it. 

Cedar Mountain is accessible by a rather poor -

road or may be reached by wa!king 3 or 4 miles 

across country from Desert View Camp, which 

is connected with El Tovar by a good road. It 

is interesting not only because it affords evidence that the Moenkopi and Shinarump formations once covered the Grand Canyon region, 

but because the Shinarump conglomerate, 

which caps it, contains petpned wood. Plate 

XXV, B, shows Cedar Mountain as seen from 

Desert View Camp~· . 

Inasmuch as the formations in Cedar Mountain are exposed within 2 miles of the rim of the 

Grand Canyon they may be conside ed a part 

of the Grand Canyon stratigraphic s ction, and 

I have therefore included a section f them in, 

the present report: This section, hich follows, is probably inaccurate in deta l, because 

I obtained the thicknesses of the bed by rough 

aneroid measurement and because he exposures of many' beds are poor owing to the apron 

of debris that cloaks the slopes of the 1 ountain. 

However, the section serves· to give a general 

idea of the character and succession o the beds . 

Section of beds exposed on south side of Ced _Mountain, 

ViShnu quadrangle. 

Shinarump conglomerate (Upper? Triassic): 

siliceous conglomerate or pebbl grit 

composed chiefly of pebbles of 

or jasper embedded in a mat x of 

quartzose sand; caps Cedar Mounta and 

forms strong cliff. Cross-bedded th oughout; texture variable, some bed :fine 

grained, others coarse grained. Ro nded 

pebbles of white quartz a quarter of an 

inch to an inch in diameter predo inate 

in the coarser beds; the jasper pe b b es are 

of different colors and a.re band and 

variegated; probably the jasper is petrified wood. Several logs of pe ri:fied 

wood are embedded in the conglo ~rate. 

The constituent pebbles of the con 'Iomerate are unidentifiable with an rock 

Feet. 

in the underlying Moenkopi.. . . . . . . . . . 25 
72 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1922. 

Unconformity(?). The contact between the Shinarump conglomerate and the underlying 

shale is concealed nearly everywhere by 

talus. The only exposure noted, a few 

feet in horizontal extent, shows conglomerate resting on reddish-brown sandy 

shale; lithologic change from shale to 

conglomerate very sharp. 

Moenkopi formation (Lower Triassic): 

1. Slope; practically all covered by debris. 

The few outcrops . consist o£ thinly 

laminated reddish-brown shale or shaly 

sandstone _______ ..................... . 

2. Strong cliff; very mMSive reddish-brown 

.fine-grained, strongly cross-bedded sandstone . . . _ . _ .................. ~ ....... . 

3. Slope; soft, thinly laminated tan to reddishbrown sandy shale. Outcrops covered 

·with white saline efflorescence, indicating 

the presence of much saline material in 

the rock. .. ___ . _ . _ . _ . _ . _________ . _____ _ 

4. Weak cliff; rather massive buff sandstone 

exhibiting indistinct cross-bedding_._. 

5. Slope; thinly laminated tan sandstone or 

sandy shale_ . _ .... _ ................. _ . 

6. Cliff; light yellowish-buff to creamy-buff 

fine-grained rather mMSive cross-bedded 

sandstone . ___ . _ ...................... . 

7. Long, gentle slope almost entirely covered 

by talus. The few outcrops are mostly 

thinly laminated soft brownish or reddish 

shale. The upper part of this member, 

just under the overlying buff sandstone, 

is bright-vermilion shale; the basal portion is slabby fine-grained thin-bedded 

sandstone which exhibits lemon and tan 

tints and is mark~dly calcareous ...... _ . 

8. Tiny cliff; greenish-buff, thinly laminated 

crystalline limestone, somewhat sandy 

in places_ .. _ . ___ ........ _ . _ ........ . 

9. Slope; platy, very thinly laminated greenish 

and brownish-buff calcareous shaly 

, sandstone, pMSing up into brownish-buff 

and vermilion beds of the same character 

10. Curious gnarly cherty bed. In places a 

conglomerate of angular chert fragments; 

in places a massive gnarly sandy chert. 

Thickness variable. __ ............. _ .. . 

11. Massive yellowish-buff fine-grained sandstone. Thickness variable ............ . 

Unconformity(?). Theirregularityofthe beds at this 

horizon and the presence in them of 

brecciated chert indicate a surface of 

erosion, but the outcrops a.re not of sufficient extent to afford conclusive evidence. 

Feet. 

60 

80 

130 

16 

5 

18 

150 

1 

15 

0-4 

0-2 

481 

Kaibab limestone (Permian): 

1. Massive buff sandstone containing lenses. 

of chert and many casts of fossils; casts of 

Productus? are the most abundant. 

Thickness of bed variable and its surface 

Feet.. . 

appears wavy ................ _ ....... _. 2-& 

2. Partly concealed bed, making slope. 

Apparently consists of alternating thin 

layers of chert and lemon-buff sandstone _ .. : ........... __ .. ___ . __ . . . . . . . . 5-

3. Cliff; massive gray to buff sandstone; calcareous; contains casts of Productus? _... . 7 

4. Not measur~d. Thin layers of rubbly chert 

and fine-grained lemon-buff to pinkishbuff sandstone. Thickness at least 40 · 

feet. The beds forming · this cherty 

series are plainly equivalent to similar 

cherty beds in the Kaibab limestone that 

are exposed in the wall of the Grand 

Canyon just under the rim at Desert View, 

3 miles away. 

The section just given may be compared 

with Gregory's type section of the Moenkopi 

f0rmation for the Little Colorado Valley, 

measured 5 miles below Tanner Crossing, in the. 

wall of the valley. 63 Tanner Crossing is about 

20 miles southeast of Cedar Mountain. Both. 

sections include the entire Moenkopi, with the. 

Shinarump ·conglomerate exposed above it 

and the top of the Kaibab limestone exposed 

below. Gregory's. section of the Moenkopi is 

389 feet thick, whereas the section at Cedar 

Mountain above the Kaibab limestone measures 

481 feet. The Cedar Mountain section differs 

from Gregory's section chiefly in that it con-· 

tains massive beds· of cross-bedded sandstone. 

in the upper part, and it is conceivable that 

this massive sandstone at Cedar Mountain 

represents the De Chelly sandstone of the 

Navajo country, which, as Gregory has shown, 

is sporadic in occurrence and occupies a. 

stratigraphic position between the Moenkopi 

formation and the Shinarump conglomerate. 

However, great and sudden variability in 

lithology both vertically and horizontally is. 

a normal feature of the Moenkopi, as Gregory 

has pointed out. Moreover, cross-bedded sandstone is not uncommon in the Moenkopi, so that 

its presenc'e at Cedar Mountain is not necessarily significant. Unconformities between the 

Shinarump and Moenkopi and between the. 

Moenkopi :and Kaibab can not b~ determined

by conclusive evidence at Cedar Mountain~ 

63 Gregory, H. E., op. cit., p. 24. 
PALEOZOIC FOR,MATIONS OF THE GR.AND CANYON. 73 

because the exposures of the contacts between 

the formations are of small extent, but inasmuch as Gregory has shown conclusively that 

these unconformities exist in the general 

region and are widespread, it i~ highly probable 

that the features I have described as occuring 

at the contacts between the formations at 

·Cedar Mountain indicate their presence. 

I obtained no fossils in the Moenkopi at 

Cedar Mopntain, but fossils collected in ·it by 

Longwell 64 in Nevada and determined by 

Girty show that its age is Lower Triassic. 

Therefore the probable unconformity between 

the Moenkopi formation and the Kaibab 

limestone separates deposits of the Paleozoic 

and Mesozoic eras. 

Gregory 65 has tentatively a~signed the Shinarump conglomerate to the Upper Triassic. 

64 Longwell, C. R., op. cit., p. 50. 

65 Gregory, H. E., op. cit., p. 41.