DEPARTMENT OF THE INTERIOR

Ray Lyman Wilbur, Secretary

U. S. GEOLOGICAL SURVEY 

George Otis Smith, Director

Bulletin 808

GEOLOGY OF THE DE QUEEN AND CADDO GAP 

QUADRANGLES, ARKANSAS

BY

HUGH D. MISER AND A. H. PURDUE

 *"**» » * 

» J** J»* .* * 

UNITED STATES

GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1929
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 11 « »t. « .« * »..« « 

» * * » * 
CONTENTS

Bag.

Abstract.. ________________________________.__--_..__._---.-_ ix

Present investigation -_-______-______________-_---___------_-----_- 1

Location and general relations.______________________-------------__ 4

General geography and geology of the Ouachita Mountain region.-_-___ 6

Surface features__________-____________________---_--__------- 6

j Climate and vegetation_________________--______________----_-_ . 8

' Stratigraphy __________--_-_______-_____-________------------- 9

Structure____________________________________________________ 11

General geography and geology of the Arkansas Valley _________ ____ 12

General geography and geology of the Gulf Coastal Plain._________-_-- 13

Geography. _________________________________________._____. 14

Surface features_________________--__-__-_-__-_-------_------- 14

Drainage --____-_-----_-__________._._________________-__-__- 18

Culture._____________________________________________________ 21

 Descriptive geology_______________________________________________ 22

Stratigraphy. ______________________________________-----. 22

General features........___._______________-__-___------__ 22

Cambrian system.._______________________________________ 23

, Ordovician (?) system...__________________________________ 24

Crystal Mountain sandstone.____________-_____--_----_ 24

] Ordovician system....____________________________________ 25

! - Mazarn shale__-______-__-_-__--_--__-_--_--._----.-_ 25

Blakely sandstone.________________________.___________ 29

Womble shale._______________________________________ 31

Bigfork chert..__--______-______--_____---______-_---_ 36

Polk Creek shale.-____--_____.____________-. 39

Silurian system__________________________________________ 42

Blaylock sandstone-____--______---___-_---_____-----__ 42

Missouri Mountain slate._-_______-_-___--______--_____ 45

» Devonian system_________________ __________.____________ 49

Arkansas novaculite.___---____-_-___-__-_--____-_-_-__ 49

Carboniferous system.______________________________________ 59

Mississippian series..__________________________________ 59

Stanley shale.____________________________________ 59

Jackfork sandstone._______________________________ 75

Pennsylvanian series...________________________________ 77

Atoka formation__________________________________ 77

Cretaceous system._______________________________________ 79

Comanche series (Lower Cretaceous)____________________ 79

Trinity formation_________________________________ 79

Gulf series (Upper Ci_taceous)__--___._________._______ 86

Woodbine formation.._____________________________ 86

; Tokio formation. _________________________________ 90

, . Brownstown marl.________________________________ 94

'<f\ in
fV CONTENTS

Descriptive geology Continued.

Stratigraphy Continued. Page

Tertiary (?) system....._________________________________ 95

Quaternary system ________________________________________ 96

Terrace deposits______________________________________ 96

Various age designations of gravel deposits ______________ 97

Alluvium.____________________________________________ 99

Igneous rocks.._______________________________________________ 99

General features._________________________________________ 99

Prairie Creek peridotite area______________________________ 100

Location and topography._____________________________ 100

Rocks associated with the peridotite-____________________ 100

Character of the peridotite_____________________._______ 101

General features._________________________________ 101

Intrusive peridotite._____________-__________--_____ 102

Volcanic breccia.________________-__--______-_-..-_ 105

Tuff and fine-grained breccia.___-___-_-__-_---__--_ 107

Veins in the peridotite_____________________-_--_______- 109

Dike near mouth of Prairie Creek.._________________________ 109

Kimberlite peridotite area._________________________________ 110

American peridotite area-___-________________--_---_--__-_- 111

Black Lick peridotite area_-__--______________-_---_---__-_- 112

Relation of the peridotite to the other igneous rocks of Arkansas. 113

Age of the peridotite-_____________________________________ 114

Comparison of Arkansas and South African rocks__________--_- 115

Structure._________________________________________________ 117

General features._________________________________________ 117

Structure of the Paleozoic rocks..__-_______.__-__-__-_-__--- 117

Folding_______________...___________.___-__-.__.._.-_ 117

Ouachita anticline.._______________________________ 118

Crystal Mountain anticline.----.----------.---- 119

Cossatot anticline._____-____._____-_____-_---- 121

Mazarn syncline._________---____--_-___--.-_- 122

Cross Mountains anticline.-_------._-- __----__-- 123

Athens Plateau______-________________--_--_--_.-. 123

Cove Basin.._____________________________________ 124

Faulting.______-___..._-___________-___-___---..---._ 124

Metamorphism. ___________________________------__-_- 125

Structure of the Cretaceous rocks.__.____________--_-_-_-_-- 126

Geologic history______________________________________-_--_-_____- 126

Cambrian period.___________________.._.__--_-____-----__----. 127

Collier deposition______________________________________-._ 127

Ordovician (?) period.___________-_______-_---___---------___-- 127

Crystal Mountain deposition.________-_________-__-----_--- 127

Ordovician period_-_--__--__---_--__-_-__------_---_---------- 128

Mazarn, Blakely, and Womble deposition.___________-__--.-_ 128

Bigfork deposition_______________________________________ 129

Polk Creek deposition.____________________________________ 129

Silurian period.____________-________-__-___-____-_-_--__-_-__- 130

Blaylock deposition_________'-_________--_-_---_--.-_------ 130

Missouri Mountain deposition________-_____--_____-_--__--- 131

Devonian period._______________________-_----__---_---------- 131

Arkansas novaculite deposition... __________________________ 131
)' CONTENTS V

Geologic history Continued. Page

Carboniferous period____-_----____--__------------------------ 132

Folding and uplift_____--_-___________________---------------- 135

Late Pennsylvanian, Permian, and Mesozoic time_____.._.-_-_---_ 136

Ouachita peneplain.-_--_-__-_____-_-------------_-------- 136

j Deposition in Lower Cretaceous time._______.-----__------_- 139

I Intrusion of igneous rocks.__-__-___---_---...--------------- 140

Deposition in Upper Cretaceous time._____--------__-----_-- 141

Drainage during Cretaceous time._________--__---__---__--- 143

Tertiary and Quaternary time.___________-_____-_-_--__-------- 144

Economic geology.__________-_____________-_-____^-_-_---__------- 146

Diamonds._________________-__--_____-----_-_---_------------ 147

History and occurrence._----_---__-----_------------------ 147

Production and character._______________________-_-_-_---- 147

Mining and treatment of diamond-bearing material._____-_.__ 149

Concentrate minerals associated with the diamonds_____-_._-_ 150

Antimony..____________________________________.___--____--. 150

Slate._-_----_-_--_-------_--_--_-_--------_------___-------- 153

General features__--_____-____-_____-__-__------__-------. 153

Mazarn and Womble shales,___-_____-___-___-----_-------- 154

Polk Creek shale._______-___________-_____-_-_--__-------- 154

Missouri Mountain slate._-__________-_____-_-_--___----_-- 154

Stanley shale_______-___________________--___--_-_---_--_- 157

Asphalt deposits_--__-_--______________--_______---_---------- 157

General features___--__-_-_-_________________--_-_-------- 157

Local details_______-____________________-__---_-_---_--_- 157

____---_______________-_____-_--_----___---- 157

_-_.__-.-___________-_-_____----____--.-_-- 158

Murf reesboro. ________________________________________ 159

Lebanon _____________________________________________ 159

Value of deposits._--_----_-______-_-__-__-_--__-__----_-. 161

Origin of the asphalt and possibility of oil and gas in the quadrangles.... ____________________________________________ 161

Drilling for oil________________________________________ 162

Tripoli..----_--___-__--_-_.______________________________.__ 162

Lead and zinc deposits..,.____________________________________ 166

General features__________________________________________ 166

Bellah mine_____________________________________________ 166

Davis mine______________________________________________ 167

Prospects ________________________________________________ 168

Manganese ore_______________________________________________ 170

Iron ore_____________________________________________________ 173

Quartz crystals.______________________________________________ 174

Gypsum.____________________________________________________ 174

Celestite.._________________________________________________ 175

Phosphate ___________________________________________________ 175

Pyrite and marcasite__-______.________________________________ 175

Copper, gold, and silver.______________________________________ 176

Clay________________________________________________________ 176

Shale.___________________________________________________ 177

Lime _________________________________________________________ 177

Building stone._______________________________________________ 178

Sand_ ______________________________________________ 178
VI ILLUSTRATIONS

Economic geology Continued. pag»

; i Novaculite for pottery and glass.___-____.----_-_------------.-_ 178

 Oilstones______________.___.___...._.._....._.-.._.. 178

Pebbles for tube mills.-....-..____._-----.._----------..-_ 179

Road material.___________..__________________-___-___-----___- 181

. Water resources......................__________---_.___-._.-_ 182 i

Wdlfl.................................................... 183 /

Cold springs....-___-_______________------_----_---------. 186

! Hot springs............_____-___.__-_._---------_-_---_-. . 186

: ; Water power._______________._____.--__...-_--__--_-.._-- 188

Soils..._...-..._....-._.........-. - ................. 189

Timber._..._._._..._....__...__.-.-.-.----.--------------.-- 190

Index... ____._________.______.______._-_._-- . . . - - 193

ILLUSTRATIONS

Page

PLATE 1. Map showing the topographic divisions and the drainage 

pattern of the De Queen and Caddo Gap quadrangles, 

Arkansas and Oklahoma...............________________ 4

2. Standing Rock, on Board Camp Creek, Ark____.___________ 20

3. Geologic map of the De Queen and Caddo Gap quadrangles,

Arkansas and Oklahoma._________________________ In pocket.

4. Generalized section of the Paleozoic rocks exposed in the De

Queen and Caddo Gap quadrangles, Arkansas and Okla- i 

horna....___._.._._________________________________ 28 '.

5. Generalized section of Cretaceous rocks exposed in the De 

Queen and Caddo Gap quadrangles, Arkansas and Oklahoma_________________-________-_____..-_____-.___-_-- 28

6. A, "Ribboned" shale with horizontal cleavage that cuts across 

black and green layers; B, Limestone in Womble shale, half 

a mile southeast of Plata, Ark__________________________ 28

7. A, Lower division of the Arkansas novaculite on the east side 

of Caddo River at Caddo Gap, Ark.; B, Sandstone in the 

Stanley shale in a railroad cut at Vandervoort, Ark_______ 28

8. A, Polished surface of specimen of tuff from the Stanley shale

in the De Queen quadrangle; B, Hatton tuff lentil of Stanley f 

shale, half a mile south of Hatton, Ark_______,.___-____-- 68

9. A, Stanley shale in Whitley railroad cut 2K miles south of 

Gillham, Ark.; B, Pike gravel member of the Trinity formation at Bluff Ford on Muddy Fork, 1 mile west of Nathan, 

Ark.___.,_______________-____----____-_-__-_-----_-- 68

10. Geologic map of the Prairie Creek area of peridotite in T. 8 S., 

R. 25 W., 2}^ miles south-southeast of Murfreesboro, Pike 

County, Ark._______._____________-_-__-----_-----_-- 100

11. A, Intrusive peridotite ("hardebank") in the northern part of 

the Mauney mine, near Murfreesboro, Ark.; B, Altered 

volcanic breccia ("blue ground") in cut of Ozark mine near 

Murfreesboro, Ark___________________________--_--_-_- 100

12. A, B, Photomicrographs of intrusive peridotite ("hardebank")

from Prairie Creek area, near Murfreesboro, Ark.__.____.. 104
ILLUSTRATIONS VH

Page

PLATE 13. A, Photomicrograph of blue-gray tuff from drill hole No. 3 

near Arkansas mine, near Murfreesboro, Ark.; B, Polished 

surface of volcanic breccia ("blue ground") from southern 

part of Mauney mine, near Murfreesboro, Ark-----.--.--. 104 

I 14. Maps showing the distribution of the peridotite at the American 

I and Kimberlite mines and at the Black Lick, in T. 8 S., R. 25 

\ W., Pike County, Ark..____________________ 108

15. Structure sections across the De Queen and Caddo Gap quadrangles, Arkansas and Oklahoma-_________________ In pocket.

16. Sections through several mountains in the De Queen and Caddo 

Gap quadrangles, Arkansas and Oklahoma, illustrating their 

complicated structure. _ ___---___---_-_>__-__-.-_____-_- 120

17. A, Diamonds from the Arkansas mine, near Murfreesboro, 

Ark.; B, A cluster of quartz crystals from the Crystal Mountains, Ark.___________--_._-___________---__.-_-______ 148

18. A, Diamonds being mined at the Arkansas mine by means of

a jet of water and then carried through a sluice to the plant; 

B, Diamond plant at the Arkansas mine_._____-__--_____ 148 

FIGURE 1. Index map of southwestern Arkansas and parts of adjacent

States._______________------______________-_---_----- 4

2. Outline map of the Ouachita Mountain region, showing its

relations to the surrounding regions.____________________ 5

3. Geologic map of parts of Arkansas, Oklahoma, and adjoining

States.____________________.-___----- 6

4. Section of dike of weathered peridotite cutting clay of the

Trinity formation at the Kimberlite mine, Pike County, Ark. 110

5. Structure section through the American mine, Pike County,

Ark-__-------.._....----------------__-.-__-------.- 112

6. Section in the De Queen quadrangle, illustrating the fan-shaped

arrangement of the folds_-____-_--__--------.._--------- 122

7. North-south section through the Caddo Gap quadrangle and 

areas north and south of it, showing the relations of the 

Hot Springs and Ouachita peneplains_______---_-------- 138

8. Map of the southern part of the De Queen quadrangle, Arkansas 

and Oklahoma, showing by contours the maximum depth 

to which wells should be drilled for artesian water-___--__ 184

9. Map of the southern part of the Caddo Gap quadrangle, Arkansas, showing by contours the maximum depth to which 

wells should be drilled for artesian water.____-.___-..--_- 185

INSERT

Page 

Various classifications of formations of Paleozoic age exposed in the

Ouachita Mountain region of Arkansas and Oklahoma._-.______.___ 22

ABSTRACT

Location and surface features. The De Queen and Caddo Gap quadrangles, 

which embrace an area of almost 2,000 square miles, lie mainly in southwestern 

Arkansas but include a narrow strip along the eastern border of Oklahoma. 

The northern three-fourths of the quadrangles lies in the Ouachita Mountain 

region, and the remainder in the Gulf Coastal Plain.

Rocks of the Ouachita Mountain region. The rocks in the Ouachita Mountain region include shale, sandstone, chert, and novaculite, with a little limeStone and volcanic tuff, and range in age from Cambrian to Pennsylvanian. 

Their aggregate thickness is about 25,000 feet.

The novaculite (Arkansas novaculite, in part Middle Devonian, in part 

Upper Devonian, and possibly in part Mississippian), is the rock of chief scientific as well as geographic interest in the quadrangles. It occurs in beds that 

aggregate a maximum thickness of almost 1,000 feet. It is so resistant that 

the beds, which are usually inclined at high angles, form the crests of most 

of the high mountain ridges of the quadrangles. The novaculite is for the 

most part massive, it breaks with a conchoidal fracture, and the prevailing 

color is white. It is a fine-grained siliceous rock composed almost entirely of 

closely fitting microscopic grains of silica and resembles in appearance the 

white varieties of Carrara marble. Its unusual character has led to many 

opinions as to its origin. The authors, with other geologists, hold the view 

, that it is a variety of chert and that the silica was deposited by chemical 

precipitation.

The rocks of the Ouachita Mountain region contain few fossils. Those believed to be of Cambrian age have thus far yielded none. The Ordovician rocks 

have furnished many species of graptolites but few other fossil forms. The 

Silurian rocks also contain several species of graptolites. The novaculite and 

interbedded shale are almost barren of fossils but have yielded conodonts, 

sporangites, linguloids, and silicified wood. The only identifiable fossils obtained from the Mississippian and Pennsylvanian rocks, which consist of a 

great succession of sandstone and shale measuring about 18,000 feet in thickness, are one collection of plants; fragmentary unidentifiable plants and invertebrates are found sparingly at a few places.

The succession of Paleozoic rocks is broken by unconformities, so that some 

formations vary in thickness from place to place, but the variations in thickness and also the disappearance of formations are attributable for the most 

part to conditions of deposition.

The Paleozoic sediments were deposited in a geosynclinal basin that lay north 

of a land area occupying the present region of Louisiana and eastern Texas and 

south of the present Ozark region, which was land during most of Paleozoic 

time. The sediments were derived mostly from the southern land mass, and 

the material for the bed of volcanic tuff in the Mississippian rocks was ejected 

from volcanic vents that were active during a probable mountain-making epoch 

on the southern land. The shallow-water nature of most of the sediments indicates that the bottom of the geosynclinal basin gradually subsided during their 

deposition.

IX
X ABSTBACT

The rock strata were deformed by folding and faulting near the middle of 

the Pennsylvanian epoch, by compressive movements from the south. This 

deformation has compressed the strata into about half their original horizontal 

extent.

Sedimentary rocks of Coastal Plain. The sedimentary rocks of the Coastal 

Plain are of Upper and Lower Cretaceous age and include gravel, sand, clay, 

limestone, and some water-laid volcanic tuff, all aggregating a thickness 

of several hundred feet. The strata lie in a nearly horizontal position, 

dipping 50 to 100 feet to the mile toward the south. They rest upon the 

truncated upturned edges of the steeply dipping Paleozoic rocks, which form 

a floor that has only minor irregularities and undulations. An angular unconformity also separates the Lower Cretaceous from the Upper Cretaceous strata, 

and a similar unconformity separates the Woodbine and Tokio formations 

("Bingen formation" of early reports), both of Upper Cretaceous age.

The Cretaceous sediments, except the beds of tuff, were derived from the 

Ouachita Mountain region to the north. Notable among them are several 

beds of gravel of wide extent, the thickest measuring about 100 feet. The beds 

are composed mostly of pebbles of novaculite derived from outcrops of this 

rock in the Ouachita Mountains. The tuffaceous material was ejected early in 

Upper Cretaceous time from volcanic vents at the site of the present diamond 

mines near Murfreesboro, in the Caddo Gap quadrangle, and from other vents 

that presumably existed a short distance south of the quadrangles. The rocks 

filling all the vents, except those near Murfreesboro, are now concealed by 

Upper Cretadeous strata. The bedded tuff is all water-laid, though portions 

of the deposits were not well sorted during their deposition.

Igneous rocks. The intrusive rocks consist of peridotite of early Upper 

Cretaceous age exposed in four relatively small areas near Murfreesboro. Three 

forms of the peridotite directly associated with the vents are recognized massive porphyritic peridotite, breccia, and tuff. After the intrusion and cooling 

of the porphyritic rock violent explosions followed, breaking up the previously 

solidified rock. Fragments so produced make up the breccia and tuff.

Physiographic history. The highest ridges of the Ouachita Mountains in 

the quadrangles attain an altitude of 2,360 feet above sea level, but 18,000 feet 

or more of Paleozoic rocks have been removed from above the crests of these 

ridges. The available evidence indicates the presence of two peneplains called 

the Ouachita and the Hot Springs. The Ouachita peneplain is marked by the 

narrow crests of the mountain ridges in the northern parts of the quadrangles. 

It slopes southward and passes beneath the strata of Lower Cretaceous age, 

forming the smooth floor upon which the sediments of this age were deposited 

In the southern parts of the quadrangles. This floor dips southward at rates 

ranging from 80 to more than 100 feet to the mile.

The Hot Springs peneplain, of Tertiary age, occurs at a lower altitude in the 

Ouachita Mountain region than the Ouachita peneplain and is marked by the 

upland level of intermontane basins and by a piedmont plateau (Athens 

Plateau) south of the mountains. The altitude of the peneplain surface ranges 

from 750 to 1,250 feet, being highest to tlie north. Erosion since Tertiary 

time has greatly dissected this peneplain, and the deepest stream valleys are 

now 350 feet below it

Mineral resources. The most valuable mineral resources of these quadrangles are clay, diamonds, and road material, all of which have been mined. 

Lead, zinc, and antimony minerals, asphalt, slate, gypsum, building stone, 

quartz crystals, and limestone for lime have also been mined at times.
ABSTEACT XI

Deposits of tripoli, pyrite, marcasite, fuller's earth, iron ore, and manganese 

ore have been explored.

Diamonds were discovered near Murfreesboro in 1906. Since then mining 

for diamonds has been carried on intermittently at several mines, and more 

than 10,000 stones have been recovered. The stones are mostly white, 

yellow, and brown and range in size from a small fraction of a carat to 

many carats. Some of them are so small that 250 of them would be required 

to weigh 1 carat. The largest weighed 40.23 carats. The diamonds are 

found, for the most part, in the soft weathered portions of the peridotite 

breccia that occurs in the several extinct volcanic necks near Murfreesboro.

Oil and gas have been prospected for in the Coastal Plain along the southern 

edge of the quadrangles, but thus far neither of these substances has been 

found in paying quantities. There is no possibility that either will be found 

in commercial quantities in the greatly deformed and metamorphosed Paleozoic rocks of the Ouachita Mountain region.

Forests. The quadrangles have dense forests of yellow pine, oak, and 

other hard woods, and only a comparatively small proportion of their area 

has been cleared and put into cultivation. Much of the rugged mountainous 

region is Included in the Ouachita National Forest.

GEOLOGY OF THE DE QUEEN AND CADDO GAP 

QUADRANGLES, ARKANSAS

By HUGH D. MISER and A. H. PURDUE

PRESENT INVESTIGATION

x -The field study of the geology of the De Queen and Caddo 'Gap 

quadrangles extended over a period of many years, and although the 

scientific and economic results from the study are here set forth fully 

for the first time in a single report, a number of publications have 

been issued that have presented some of the more important results. 

These are listed below.

Purdue, A. H., A new discovery of peridotite in Arkansas: Econ. Geology, 

vol. 3, pp. 525-528, 1908.

Purdue, A. H., The slates of Arkansas, 95 pp., Arkansas Geol. Survey, 1909; 

U. S. Geol. Survey Bull. 430, pp. 317-334, 1910.

Purdue, A. H., Structure and stratigraphy of the Ouachita Ordovician area, 

Ark. [abstract] : Geol. Soc. America Bull., vol. 19, pp. 556-557, 1909.

Purdue, A. H., Recently discovered hot springs in Arkansas [Caddo Gap, Montgomery County, Ark.]: Jour. Geology, vol. 19, pp. 272-275, 1911.

Miser, H. D., New areas of diamond-bearing peridotite in Arkansas: U. S. 

Geol. Survey Bull. 540, pp. 534-546, 1914.

Miser. H. D., Manganese deposits of the Caddo Gap and De Queen quadrangles, Ark.: U. S. Geol. Survey Bull. 660, pp. 59-122, 1917.

Miser, H. D., and Purdue, A. H., Gravel deposits of the Caddo Gap and De 

Queen quadrangles, Ark.: U. S. Geol. Survey Bull. 690, pp. 15-29, 1918.

Miser, H. D., and Purdue, A. H., Asphalt deposits and oil conditions in southwestern Arkansas: U. S. Geol. Survey Bull. 691, pp. 271-292* 1918.

Miser, H. D., Mississippian tuff in the Ouachita Mountain region [abstract]: 

Geol. Soc. America Bull., vol. 31, pp. 125-126, 1920.

Miser, H. D., Llanoria, the Paleozoic land area in Louisiana and eastern 

Texas: Am. Jour. Sci., 5th ser., vol. 2, pp. 61-89, 1921. Abstract, Geol. Soc. 

America Bull., vol. 32, pp. 40^41, 1921; Washington Acad. Sci. Jour., vol. 11, 

pp. 444-445, 1921.

Miser, H. D., and Ross, C. S., Diamond-bearing peridotite in Pike County, 

Ark.: Econ. Geology, vol. 17, pp. 662-674, 1922; U. S. Geol. Survey Bull. 735, pp. 

279-322, 1923; Smithsonian Inst. Ann. Rept. for 1923, pp. 261-272, 1925.

Miser, H. D., and Ross, C. S., Volcanic rocks in the Upper Cretaceous of 

southwestern Arkansas and. southeastern Oklahoma: Am. Jour. Sci., 5th ser., 

vol. 9. pp. 113-126, 1925.

1
2 DB QUEEN" AND CADDO GAP QUADRANGLES, ARKANSAS

Miser, H. D., Lower Cretaceous (Comanche) rocks of southeastern Oklahoma 

and southwestern Arkansas: Am. Assoc. Petroleum Geologists Bull., vol. 11, 

I>p. 443-453, 1927.

Miser, H. D., and Honess, C. W., Age relations of the Carboniferous rocks of 

the Ouachita Mountains of Oklahoma and Arkansas: Oklahoma Geol. Survey 

Bull. 44, 1927.

Miser, H. D., Structure of the Ouachita Mountains of Arkansas and Oklahoma [abstract]: Washington Acad. Sci. Jour., vol. 18, pp. 266-267, 1928; Geol. 

Soc. America Bull., vol. 39, pp. 180-181, 1928.

Ross, C. S., Miser, H. D., and Stephenson, L. W., Water-laid volcanic rocks 

of early Upper Cretaceous age in southwestern Arkansas, southeastern Oklahoma, and northeastern Texas: U. S. Geol. Survey Prof. Paper 154, pp. 175-202, 

1929.

The field work was begun in 1907 and continued intermittently 

until 1925. The work in 1907 was done under a cooperative agreement between the United States Geological Survey and the Arkansas 

Geological Survey and involved primarily an investigation of the 

slate deposits of west-central Arkansas but also the mapping of the 

rocks in the mountainous part of the Caddo Gap quadrangle. In 

that year A. H. Purdiie, State geologist of Arkansas, had charge of 

the work and was assisted by R. D. Mesler and H. D. Miser. All the 

subsequent work in the Caddo Gap quadrangle, as well as all in the 

De Queen quadrangle, was done by the United States Geological 

Survey. The work since 1907 is briefly outlined below. In 1908 

Mr. Purdue, assisted by Mr. Miser, completed the mapping of the 

rocks of the Caddo Gap quadrangle with the aid of valuable suggestions from C. W. Hayes, chief geologist, J. A. Taff, and E. O. 

Ulrich, who visited the field for several days. In 1910 Mr. Purdue, 

assisted by Mr. Miser, reviewed a part of the previous work in the 

Caddo Gap quadrangle and mapped the rocks in most of the mountainous portion of the De Queen quadrangle. In 1911 these geologists 

did additional work in both the De Queen and Caddo Gap quadrangles, and in 1912 Mr. Miser, assisted by Mr. Mesler, completed the 

mapping of the rocks in the De Queen quadrangle and then reviewed 

^^me of the earlier work in the Caddo Gap quadrangle. In 1913 

Arthur Keith, and Messrs. Purdue and Miser spent several days in a 

field conference in the Caddo Gap quadrangle. During the conference the first identifiable fossils in the Blaylock sandstone, of Silurian 

age, were discovered. In 1914 Mr. Miser obtained a small collection 

of fossil plants from the Stanley shale near Gillham, Ark., also the 

first fossils from the Arkansas novaculite. In 1916 he made a special 

study of some of the mineral deposits of the quadrangles, including 

the deposits of diamonds, manganese ore, gravel, and asphalt, and in 

1917 he revisited the diamond mines. An investigation of the volcanic ash and tuff in the "Bingen formation," of Upper Cretaceous 

age, in the Caddo Gap quadrangle and adjoining areas to the south 

and southwest was made in 1923 by Clarence S. Ross and Mr. Miser.
PRESENT INVESTIGATION 6

Also in that year other fossil plants were collected from the Stanley 

shale at the earlier discovered locality near Gillham by Mr. Miser. 

(See pi. 9, A.) The aggregate time spent in collecting fossils at this 

locality was eight days, so scare are the fossils and so difficult are the 

conditions for collecting them. Besides the above work the authors 

made frequent reconnaissance studies of adjoining areas, and Mr. 

Miser was joined in 1923 by C. W. Honess for a field conference of a 

few days in the De Queen and Caddo Gap quadrangles. In 1925 Mr. 

Miser joined in the field Messrs. L. W. Stephenson and C. H. Dane 

for a few days in a study of the " Bingen " (Woodbine and Tokio) 

and other formations of Upper Cretaceous age in and near the Caddo 

Gap quadrangle. Mr. Dane was making at that time a special study 

of the deposits of Upper Cretaceous age in southwestern Arkansas 

under a cooperative agreement between the United States Geological 

Survey and the Arkansas Geological Survey. For some of the information on the Tokio formation the present writers are indebted to 

Mr. Dane.

Much of the writing for the present report was done by Mr. 

Purdue before his death in 1917, but all the office work on the report 

since that year has been done by Mr. Miser, with the exception of the 

chapter on the diamond-bearing peridotice, a large part of which 

was written by Mr. Ross, to whom the specimens of the peridotite 

were submitted for microscopic examination, and a part of the description of the volcanic tuff of the Woodbine formation, which also 

was written by Mr. Ross.

Numerous published papers dealing with the geology of the quadrangles and the surrounding region have been consulted during the 

preparation of the present report, and many of them are cited at 

appropriate places in the text. Special mention is here made of a 

recent valuable report by Honess,1 which describes in detail the 

geology and mineral resources of northern McCurtain County, 

Okla., and parts of the adjoining counties.

That report gives for the first time a full description of an adjacent area whose rocks and complex geologic history are similar to 

those of the De Queen and Caddo Gap quadrangles. In fact a 

narrow strip of McCurtain County described by Honess is embraced 

in the De Queen quadrangle.

Fossils collected by the writers from the Ordovician, Silurian, and 

Devonian rocks have been studied and reported on by E. 0. Ulrich; 

fossil plants from the Stanley shale (Carboniferous) have been 

identified by David White; fossil plants from the Woodbine and 

Tokio formations (Upper Cretaceous) have been reported upon by 

E. W. Berry; fossil invertebrates from the Trinity formation

1 Honess, C. W., Geology of the Southern Ouachita Mountains of Oklahoma: Oklahoma 

Geol. Survey Bull. 32, 1923.
4 DE QUEEN" AND CADDO GAP QUADRANGLES, AEKANSAS

(Lower Cretaceous) have been identified by T. W. Stanton; some 

fossil invertebrates from the Brownstown marl have been identified 

by L. W. Stephenson; and fragmentary unidentifiable invertebrate 

fossils from the Jackfork sandstone have been studied by G. H. 

Girty arid Frank Springer, who have supplied statements concerning 

them.

LOCATION AND GENERAL RELATIONS

The De Queen and Caddo Gap quadrangles lie between parallels 

34° and 34° 30' north latitude and meridians 93°' 30' and 94° 30'

FIGURE 1. Index map of southwestern Arkansas and parts of adjacent States. The 

area included in the De Queen and Caddo Gap quadrangles is shown by the darker 

ruling. Published folios of the Geologic Atlas that describe other areas, indicated 

by lighter ruling, are as follows : 74, Coalgate ; 79, Atoka ; 98, Tishomingo; 119, 

Fuyetteville ; 122, Tahlequah ; 132, Muskogee ; 154, Winslow ; 202, Eureka SpringsHarrison ; 215, Hot Springs

west longitude. Each comprises one-fourth of a " square degree " of 

the earth's surface, which in their latitude is an area of 986 square 

miles. The combined area of the two quadrangles is therefore 1,972 

square miles. They include large parts of Pike, Polk, Sevier, Howard, and Montgomery Counties and very small strips of Clark and 

Hempstead Counties, in Arkansas, all of which lie in the southwest 

quarter of the State, and the De Queen quadrangle embraces on its 

west side a narrow strip of McCurtain County, in the southeast 

corner of Oklahoma. (See fig. 1.) The De Queen quadrangle re-
U. 8. GEOLOGICAL 8XTBVET BULLETIN 808 PLATE 1

25 Miles

MAP SHOWING THE TOPOGRAPHIC DIVISIONS AND THE DRAINAGE PATTERN OF THE DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS AND OKLAHOMA

Th» topographic divisions north of the West Golf Coastal Plain form part of the Ouachita Mountain region. The streams in the Ouachita Mountain region; especially those in the Athens Plateau, illustrate a trellis system. The streams in the West Gulf Coastal Plain illustrate

consequent drainage
LOCATION AND GENERAL RELATIONS 5

ceives its name from the town of De Queen, in Sevier County, and 

the Caddo Gap quadrangle receives its name from the gap in the 

Caddo Mountains through which Caddo River runs.

The north three-fourths of the area is in the Ouachita Mountain 

region, and the south one-fourth is in the West Gulf Coastal Plain. 

The Ouachita Mountain region extends from Little Rock, Ark., to 

Atoka, Okla., a distance of 200 miles, its east half being in Arkansas 

and its west half in Oklahoma. Its width at most places is bet\veen 

50 and 60 miles. A region that is less mountainous joins the Ouachita 

region on the north. As most of this region is a wide, comparatively

FIGUKH 2. Outline map of the Ouachita Mountain region, showing its relations to

^lic* cmi'i'mm/li no- vrtcvii^nc' the surrounding regions

low valley, lying between the Boston Mountains of the Ozark Plateaus on the north and the Ouachita Mountains on the south, and as 

it is largely drained by Arkansas River, it is called the Arkansas 

Valley. On the south and east the Ouachita region is joined by a 

comparatively low, gently rolling plain, which extends southward 

to the Gulf of Mexico and is called the West Gulf Coastal Plain.

In their geology and physiographic history the Ouachita Mountain 

region and the Arkansas Valley are much the same, but they differ 

markedly from the Ozark Plateaus on the one hand and the West 

Gulf Coastal Plain on the other. The location of these and other 

near-by physiographic regions is shown in Figure 2. Figure 3 is a 

generalized map of the rocks exposed.

6242 29 2
6 DE QUEEN AND CADDO GAP QUADBANGLES, ARKANSAS

GENERAL GEOGRAPHY AND GEOLOGY OF THE 

OUACHITA MOUNTAIN REGION

SURFACE FEATURES

The Ouachita Mountain region consists of a mountainous area 

known as the Ouachita Mountains and of a dissected piedmont plateau, known as the Athens Plateau, which lies along1 their southern

lOoMiles

TERTIARY CRETACEOUS CARBONIFEROUS

QUATERNARY EOCENE

CRETACEOUS CRETACEOUS

PERMIAN PENNSYLVANIAN MISSISSIPPIAN 

AND MISSISSIPPIAN

UNDIFFERENTIATED

DEVONIAN DEVONIAN SILURIAN UPPER UOWER CAMBRIAN INTRUSIVE PRE-CAMBRIAN

SILURIAN AND MIDDLE ORDOVICIAN IGNEOUS ROCKS IGNEOUS

ANDORDOVICIAN ORDOVICIAN AND CAMBRIAN (CRETACEOUS) ROCKS

UNDIFFERENTIATED UNDIFFERENTIATEO

FIGURE 3. Geologic map of parts of Arkansas, Oklahoma, and adjoining States

border. The term "Ouachita Mountain system" was first applied 

by J. C. Branner 2 to the east-west ridges that contain the novaculites, or Arkansas whetstone rocks, but in recent years the term has 

been extended so as to include not only these ridges but also a mountainous belt to the north of them and the Athens Plateau to the

8 Comstock, T. B., Report on Preliminary Examination of the Geology of Western Central 

Arkansas: Arkansas Geol. Survey Ann. Kept, for 1888, vol. 1, p. 59, 1888. Hill, R. T., The 

Neozoic Geology of Southwestern Arkansas : Idem, vol. 2, pp. 10, 175, 1888.
OUACHITA MOUNTAIN KEGION 7

south of them. The mountains in this region were earlier called by 

William Darby the " Masserne Mountains," 3 and this name was used 

later by Thomas Nuttall,4 although he spelled it " Mazern."

The Ouachita Mountains comprise many nearly east-west ridges 

and several intermontane basins. The ridges are narrow and have 

steep slopes and sharp, straight, even crests. Just west of Little 

Rock and east of Atoka they are low, scarcely exceeding 750 feet 

above sea level, or 250 feet above the valleys, but they gradually 

increase in height westward from Little Rock and eastward from 

Atoka, and the culminating point is reached in eastern Oklahoma 

near the Arkansas-Oklahoma line, where the highest point the 

west end of Rich Mountain is between 2,850 and 2,900 feet above 

sea level. ' In this part of Oklahoma and the adjoining part of 

Arkansas the ridges stand about 1,750 feet above the valleys. Some

of the principal masses are Jackfork, Windingstair, Buffalo, Seven 

Devils, and Kiamichi Mountains, in Oklahoma; Rich, Black Fork, 

and Cross Mountains, in Oklahoma and Arkansas; and Dutch Creek, 

Irons Fork, Blue, White Oak, Danville, Fourche, Crystal, Trap, and 

Zigzag Mountains, in Arkansas. Some of these masses are single 

ridges, and some are small ranges.

The intermontane basins lie mostly in Arkansas but partly in 

eastern Oklahoma. They are wide valley areas whose upland surfaces 

range from about 500 to 1,200 feet above sea level, with the height 

increasing from east to west, and they are channeled by many narrow 

valleys, which are in most places less than 250 feet below the 

general level represented by the upland surface. Mena, Ark., north 

of the De Queen quadrangle; Mount Ida, Ark., north of the Caddo 

Gap quadrangle; and the southern part of the city of Hot Springs 

are situated in such basins. Parts of three basins are included in 

the Caddo Gap and De Queen quadrangles.

The Athens Plateau is a belt of country about 15 miles wide 

which lies between the mountains of the Ouachita region on the 

north and the West Gulf Coastal Plain on the south and extends 

from a point near Arkadelphia, Clark County, Ark., westward 

across the central part of the Caddo Gap and De Queen quadrangles 

into Oklahoma, where it ends several miles west of the State line. 

It takes its name from Athens, in the Caddo Gap quadrangle. When 

the plateau is viewed from the crests of the mountains on the north 

it appears to be a practically level plain ending abruptly against 

the mountains, but when it is crossed very little level country is 

found; most of it is greatly dissected by narrow, crooked valleys of

8 Darby, William, The Emigrant's Guide to the Western and Southwestern States and 

Territories, p. 138, New York, 1818.

* Nuttall, Thomas, A Journal of Travels into the Arkansa [sic] Territory during the 

Tear 1819, pp. 110, 121, 148, 152, Philadelphia, 1821.
8 DE QUEEN" AND CADDO GAP QUADRANGLES, ARKANSAS

southward-flowing trunk streams and by many east-west valleys 

of small tributary streams, which are 350 feet or less below the upland 

surface. The interstream areas are therefore low east-west, rather 

even crested ridges. The upland surface of this plateau, formed by 

the crests of these ridges, ranges from 400 to 1,100 feet above sea level 

and is lowest at its east end and on its south side and highest on the 

north side.

DRAINAGE

The northern part of the Ouachita Mountain region is drained by 

Arkansas River and its tributaries, and the southern part by Red 

River and its .tributaries. The waters of both these streams reach 

the Gulf by way of the Mississippi. Among the tributaries of 

Arkansas River that drain the Ouachita Mountain region are Poteau 

River, in Arkansas and Oklahoma, and Petit Jean Creek and Fourche 

la Fave River, in Arkansas. Among the streams of the Ouachita 

region whose waters emp.ty into Red River are Boggy Creek, Kiamichi River, and Glover Creek, in Oklahoma; Little River and 

Mountain Fork River, in Arkansas and Oklahoma; and Rolling Fork, 

Cossatot River, Little Missouri River, Caddo River, Ouachita River, 

and Saline River, in Arkansas. The largest of these streams is. 

Ouachita River, which rises in the western border of Arkansas and 

flows south of east nearly to the east end of the Ouachita Mountains, 

and thence southeastward across the southern part of the State into 

Louisiana, where it joins Red River.

The position of the streams in much of the Ouachita Mountain 

region is dependent on the geologic structure. In general, they flow 

in courses which for rather long distances are parallel with the ridges 

bounding the valleys, but many streams in all parts of the province

have cut .their courses transverse to those of the ridges. In fact, 

the transverse courses of the large streams and of many of the 

smaller streams on the southern slope of the province are a conspicuous and rather characteristic feature of the drainage. The trend 

of most of the ridges is approximately east, whereas Mountain Fork 

River, Rolling Fork, Cossatot River, Little Missouri River, and 

some minor streams flow southward, cutting through the ridges in 

narrow water gaps, some of which are picturesque.

CLIMATE AND VEGETATION

The climate of the region on the whole is mild. It is free from 

extreme cold in winter but at times suffers intense heat in summer. 

The rainfall is abundant and commonly reaches a maximum in late 

spring or early summer and decreases to a minimum in late summer 

or early fall, when there are occasional droughts. In consequence."
OUACHITA MOUNTAIN REGION 9

of its abundant rainfall and its altitude, the region is being reduced 

by erosion, but it is only at times of heavy rains that the streams 

carry considerable quantities of detrital material. The precipitation, in sp,i.te of the rather poor soil, is sufficient to produce a heavy 

forest cover over the entire, area. Trees are of great variety, but 

white oak and a yellow or shortleaf pine are the most abundant, the 

pine predominating. Both grow on the ridges as well as over the 

less elevated areas. On the ridges the pines are more numerous on 

the southern slopes than on the northern. Large areas of the forest 

are virgin and extensive tracts are included in the Ouachita National 

Forest, formerly called the Arkansas National Forest.

Only a small part of .the region has been deforested and put ,under 

cultivation, most of the remainder being unfit for farming. Part of

the cultivated land is on the uplands, where nearly all the soil is 

poor, and the rest is on some of the main streams, where the soil as a 

rule is deep and of good quality. The agricultural lands are suited 

for general farming, stock raising, and fruit growing.

STRATIGRAPHY

The rocks of the Ouachita Mountain region are nearly all of sedimentary origin, but in its eastern part there are two small areas of 

igneous rocks accompanied by dikes, one at Magnet Cove, Hot 

Spring County, and the other at Potash Sulphur Springs, Garland 

County, Ark.

The sedimentary rocks comprise shale, sandstone, chert, novaculite, 

tuff, limestone, and conglomerate, the most abundant being named 

first. Except for their induration into hard rocks they have been 

only slightly affected by metamorphism, but this process has changed 

some of the shale to slate and certain beds of sandstone to quartzite. 

Estimates of the exposed rocks in this region and in the Arkansas 

A7alley indicate an aggregate thickness of about 30,000 feet.

The rocks in the Ouachita region range in age from Cambrian to 

Pennsylvanian. The rocks of the earlier periods are exposed in 

several belts. (See fig. 3.) The largest belt extends west by south 

from Little Rock nearly to the western border of Arkansas. The 

next largest is mainly in McCurtain County, Okla., though its east 

end reaches into Arkansas. In general, the oldest strata are exposed 

near the central portions of these belts and the later formations crop 

out to the north and south, but on account of the deformation of the 

strata and the relief of the surface much repetition of older and 

younger beds occurs in any north-south section across the country.

Many geologic epochs are not represented by rock strata, and no 

epoch is represented by formations that underlie the whole province,
10 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

for there have been frequent oscillations, which caused many alternations of deposition and erosion, and some of these changes involved 

the entire region. As a whole, however, the area now comprised in 

the Ouachita Mountain region and the Arkansas Valley was a subsiding trough (geosyncline) from Cambrian time nearly to the end 

of Carboniferous time, when it was deformed and uplifted, and most 

of it was permanently added to the land. This trough apparently 

stretched along the northern border of a Paleozoic land area, known 

as Llanoris, which lay farther south, in Louisiana and eastern Texas, 

and which is now concealed by Cretaceous and younger rocks. It is 

believed that most of the enormous amount of detrital material laid 

down in the Ouachita trough was derived from this land area.

The rocks assigned to the Cambrian system consist chiefly of unfossiliferous, highly crumpled shale, whose only known exposures are 

in a narrow belt lying between Black Springs and Mount Ida, 

Montgomery County, Ark.

The Ordovician rocks are best exposed in Arkansas and in McCurtain County, Okla. They consist mainly of shale, with a chert, the 

Bigfork, near the top, and include two sandstones, the Crystal Mountain and the Blakely. The Crystal Mountain sandstone is at the base 

of the Ordovician system and is only provisionally assigned to this 

system, a,s it has not yielded any fossils. The known aggregate thicknesses of the strata reach 4,450 feet. Graptolites whose remains are 

preserved in the black shale are the only abundant fossils.

The Silurian system is represented by the Blaylock sandstone and 

the Missouri Mountain slate, which range in thickness from 50 to 

1,800 feet. The Blaylock has yielded a single collection of graptolites.

The Devonian system is represented by the Arkansas novaculite. 

This formation is thickest in Arkansas and in McCurtain County, 

Okla., where its known thickness reaches 950 feet. It thins to the 

north and in places in Arkansas is absent. The only fossils that 

have been found in the formation came from the middle and upper 

parts. They consist of conodonts, sporangites, and linguloids, which 

were collected at Caddo Gap, Ark., and silicified wood, found at 

Glenwood and Eosboro, Ark. There is a possibility that the uppermost part of the formation may be of Carboniferous age.

The Mississippian series consists of 13,000 to 17,000 feet of sandstone and shale, with a small amount of tuff near the base. Northward in the region the sandstone beds become thinner and the relative amounts of shale increase, thereby indicating that the old land 

area (Llanoris') to the south was the source of much of the clastic 

material composing these rocks.
OTJACHITA MOUNTAIN EEGION 11

The Pennsylvanian series ,in the Ouachita Mountain region and the 

Arkansas Valley is made up largely of shale but includes much sandstone and small amounts of limestone and chert, and in the Arkansas 

Valley it contains1 minable coal beds. The aggregate maximum thickness of these sediments, most of which occur only in the Arkansas 

Valley, approximates 16,000 feet.

The rocks of igneous origin consist of masses of nephelite syenite 

and related types, which were intruded upward into the sedimentary strata probably early in the Upper Cretaceous epoch.

STRUCTURE

The sedimentary rocks in the Ouachita Mountain region have been 

subjected to intense lateral compression, which besides lifting the 

area above the sea, has produced east-west folds in the strata, so 

that their edges, exposed by erosion, now appear at the surface.

The major structural feature is a pronounced anticline, whose 

axis extends from a point a few miles southwest of Little Rock, Ark., 

west by south to the vicinity of Glover, Okla. (See fig. 3.) Its east 

and west ends are concealed by overlaps of the deposits of the Coastal 

Plain the east end by rocks of Cretaceous, Tertiary, and Quaternary age, and the west end by Cretaceous and Quaternary rocks. 

A low place in this anticline near the Arkansas-Oklahoma line 

divides it into two parts. The eastern part is known as the Ouachita 

anticline. Each of these parts is composed of numerous minor folds, 

and each is therefore really an anticlinorium.

The quadrangles herein described include parts of both these anticlinoria. The Ouachita anticline consists of four prominent .subdivisions three anticlines and a syncline. The syncline, named the 

Mazarn syncline by L. S. Griswold from the fact that it includes 

the Mazarn Basin, extends from Fancy Hill post office, in. the Caddo 

Gap quadrangle, eastward to Cove Creek station, in Hot Spring 

County, beyond this quadrangle. Lying north of the Mazarn syncline and extending throughout the length of the Ouachita anticline 

is the Crystal Mountain anticline, in which the oldest rocks of the 

region are exposed. The other two anticlines lie south of the Mazarn 

syncline, one at each end. The western one is known as the Cossatot 

anticline and includes the area occupied by the Cossatot Mountains, 

which extend westward from Glenwood, in the Caddo Gap quadrangle, to the place where they merge with the ridges north of the 

Mazarn Basin near Fancy Hill. The eastern one is known as the 

Trap Mountain anticline; it includes the area occupied by the Trap 

Mountains, which extend eastward from Elm post office, Clark 

County (east of the Caddo Gap quadrangle), to the vicinity of 

Malvern. The Crystal Mountain anticline, as defined by the authors
12 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

of this report, is the same as the Ouachita anticline of Griswold,5 

and the term Ouachita anticline is redefined by them so as to include 

the Trap Mountain and Cossatot anticlines.

None of these or any other of the major folds are simple units, but 

each consists of smaller folds overlapping one another lengthwise. 

The folds, besides being closely compressed, are in many places 

overturned, some northward and some southward. The overturning 

has caused the rocks on both sides of the structural axis to dip in 

the same direction, but as the Arkansas Valley is approached the 

folds become flatter and are not overturned, and the rocks dip in both 

directions. A marked structural feature is the overturning of the 

folds on each side- toward the Mazarn syncline, so that northward 

dips are most numerous north of it, and southward dips south of it. 

Not uncommonly adjacent folds are nearly equal in height, and the 

same beds appear and reappear at the surface. Over much of the 

Ouachita region most of the beds dip at angles of 40° or more. 

Generally the folds are smallest, most numerous, and most closely 

squeezed in thin-bedded rocks, such as shale and thin-bedded sandstone and chert.

Faults are numerous in Oklahoma, though they are not as numerous in Arkansas as might be expected in rocks that have been so 

intensely folded. Faulting in Arkansas has been limited by the 

presence of great thicknesses of shale distributed throughout the 

folded strata, which has permitted the beds to adjust themselves to 

the crustal .shortening through shearing and crumpling of the thinbedded rocks. Most of the faults are parallel with the folds and 

are thrust faults. Many of them were produced by the breaking 

of the strata in closely compressed anticlines. (See pi. 16 and fig. 6.)

Some faults appear on the south side of anticlines and others on the 

north sides; consequently some of the fault planes dip to the north 

and others to the south. Of the several major faults in Oklahoma, 

the two longest, the Choctaw and Windingstair, reach into Arkansas. 

They are 125 and 110 miles in length, respectively. The discovery 

by Mr. Miser in 1927 of a window through an overthrust mass in 

the Potato Hills, west of Talihina, Okla., indicates the presence of 

folded thrust planes in the Ouachita Mountains. All the major 

faults in that State are interpreted as having low-angle thrust planes 

that have southerly dips. .

GENERAL GEOGRAPHY AND GEOLOGY OF THE

ARKANSAS VALLEY

The Arkansas Valley throughout most of its length is a synclinal 

trough from 30 to 40 miles wide, which extends nearly east and west,

5 Griswold, L. S., Whetstones and the Novaculites of Arkansas: Arkansas Geol. Survey 

Ann. Kept, for 1890, vol. 3, p. 210, 1892.
GULF COASTAL PLAIN 13

though its west end has a southwestward trend. On the west and 

southwest this valley blends Tvith the Osage Plains, the Arbuckle 

Mountains, and the West Gulf Coastal Plain; on the east it passes 

into the Mississippi Alluvial Plain; on the south it merges into the 

Ouachita Mountains; and on the north it is joined by the foothills of 

the Boston Mountains, which form the southern limit of the Ozark 

Plateaus. This trough has been reduced by erosion to a plain having an average altitude of about 500 feet above sea level. Upon 

this plain stand Sansbois, Cavanal, Poteau, Sugarloaf, Magazine, 

Petit Jean, and Huckleberry Mountains, Mount Nebo, and other elevations of less prominence, besides a great number of ridges, hills> 

and nearly level highlands, most of which have an east-west trend. 

The highest of these mountains is Magazine Mountain, whose summit 

stands 2,823 feet above sea level. Many of the prominences, including those just named, present the appearance of buttes.

The principal stream is Arkansas River, which with its tributaries 

forms a network of broad alluvial valleys, whose general course is 

eastward, parallel with that of the trough. The rocks in this valley, 

practically all of which are of Pennsylvanian age, form a rather 

monotonous sequence of sandstone and shale that contain beds of 

coal over much of the area. As above stated, the strata have been 

folded, though less than those in the Ouachita area. The anticlines 

are generally narrower and steeper than the synclines; there is a 

tendency to overturning toward the north; and the folds decrease 

in intensity northward. In parts of Oklahoma, as the folds die out 

they blend into a slightly variable monoclinal structure, with a persistent though low inclination toward the northwest; whereas in 

Arkansas and the adjoining part of Oklahoma, as the local folding 

ceases the rocks rise toward the north in the southern monoclinal 

slope of the Boston Mountains. The structure bears a close relation 

to the topography, the long, narrow ridges indicating moderately to 

highly inclined rocks, and the buttelike mountains indicating practicalty horizontal rocks in synclinal basins.

GENERAL GEOGRAPHY AND GEOLOGY OF THE GULF

COASTAL PLAIN

The Gulf Coastal Plain is continuous with the Atlantic Coastal 

Plain and comprises a great area of lowland, which borders the Gulf 

of Mexico from the Florida Peninsula west and south into Mexico 

and extends inland in the middle Mississippi Valley region to the 

uplands of the Ouachita, Arkansas Valley, Ozark, and Appalachian 

provinces, its northern limit in this region being approximately the 

mouth of Ohio River. This plain on the whole slopes regularly 

toward the Gulf from altitudes of more than 1,000 feet at its inner 

margin to sea level along the coast. It is dissected by shallow valleys 

having1 broad flood plains and commonly one or more low terraces.
14 DJS QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

The slope continues beneath the Gulf to the edge of the continental 

shelf, about 100 miles from shore and 200 to 400 feet below sea level. 

The Gulf Coastal Plain comprises several subdivisions, but only one 

of these the West Gulf Coastal Plain is adjacent to the Ouachita 

Mountain region.

The materials that underlie the Gulf Coastal' Plain are chiefly 

gravel, sand, and clay of Cretaceous, Tertiary, and Quaternary age, 

deposited upon a submerged floor of Paleozoic and probably prePaleozoic rocks which had been deformed and rather uniformly 

reduced approximately to base-level. Most of these rocks are of 

marine origin and show that in comparatively recent geologic time 

the Gulf occupied this area and extended to the mouth of Ohio River. 

The post-Paleozoic strata now lie nearly parallel' to the general surface, but have a somewhat greater slope Gulfward, so that the 

older formations crop out nearer the inner margin, and progressively 

younger ones appear in crescentic bands nearer the coast.

GEOGRAPHY

SURFACE FEATURES

The northern three-fourths of the Caddo Gap and De Queen quadrangles lies in the southern part of the Ouachita Mountain region, 

and the remainder, a narrow belt along their southern border, lies in 

the northern edge of the West Gulf Coastal Plain. The part of the 

quadrangles that is in the Ouachita Mountain region embraces much 

of the Athens Plateau, which is a piedmont belt extending westward 

completely across the middle of the quadrangles, and this part also 

includes some of the Ouachita Mountains proper, which are composed

of groups of high ridges and intermontane basins. (See pi. 1.)

The high ridges are narrow and nearly parallel, trending in general east and south of east, and most of them are 1,500 to 2,000 feet 

above sea level. They are separated by narrow valleys that trend 

in most places parallel with the ridges but in others cut through 

them in gorges called water gaps. These ridges have steep rugged 

slopes and sharp even crests, above which rise a great many peaks a 

few hundred feet higher. The upland surface of the Athens Plateau 

and the intermontane basins lies mainly between 750 and 1,100 feet 

above sea level, but has been much dissected by V-shaped valleys. 

Many of the valleys are parallel and have a general east-west trend; 

others have crooked transverse courses; consequently the interstream 

areas consist of both parallel ridges and irregular-shaped hills. The 

part of the West Gulf Coastal Plain embraced in these quadrangles 

is extensively dissected, though most of its surface is very gently 

undulating. The surface of the quadrangles is therefore rough in 

most places and contains only small tracts of level land.
GEOGRAPHY 15

The highest point in the quadrangles is Raspberry Peak, in the 

Be Queen quadrangle, which rises 2,360 feet above sea level. The 

lowest point is slightly less than 300 feet above sea level and is on 

Rolling Fork a few miles southwest of De Queen. . The Ouachita Mountains stand up in striking contrast with the 

remainder of the quadrangles and are thus their most conspicuous 

physiographic division. Though much of this area is a rugged 

mountainous country consisting of groups of high ridges, a considerable portion is occupied by intermontane basins. The groups 

of ridges that are partly or entirely embraced in the quadrangles 

fire the Crystal, Caddo, Cossatot, and Cross Mountains, and the 

basins are the Caddo, Mazarn, and Cove. (See pi. 1.)

A small portion of the Crystal Mountains, a narrow chain of 

ridges extending from the west side of Montgomery County, Ark.,

north of east into Saline County, a distance of about 60 miles, is 

embraced in the northeast corner of the Caddo Gap quadrangle. 

They were named from the abundance of magnificent quartz crystals 

found in the hard sandstone that forms the ridges. (See pi. 17, B.) 

This part of the mountains .consists of several short eastward-trending ridges with steep slopes, whose crests have numerous peaks. The 

highest of the peaks is High Peak, 1,834 feet above sea level. These 

mountains are traversed by the headwaters of Collier Creek, along 

which there is some of the most rugged topography in the Ouachita 

Mountains.

Lying south of the Caddo Basin and the Crystal Mountains and 

north of the Mazarn Basin is a narrow chain of ridges which form 

the west end of a group extending eastward to Ouachita River near 

Hawes post office, in Montgomery County, named by Griswold 6 the 

Caddo Range or Mountains. These mountains extend westward 

across the Caddo Gap quadrangle into the De Queen quadrangle, 

where they merge with a group on the south known as the Cossatot 

Mountains. The largest mountains of this chain are the Caddo 

Mountains proper and the Missouri Mountains. Much of the western part of the Missouri Mountains is a single ridge, but the eastern 

part is broken up into several rather distinct ridges, closely associated with which is Statehouse Mountain. The highest point in the 

Caddo Mountains is an unnamed peak, 2,212 feet above sea level, half 

a mile southwest of Slatington, and there are several other peaks 

of little less altitude, among which are Hurricane Knob and Round, 

Lost, and Fork Mountains. The western part of the Caddo Mountains proper is a ridge that is imperfectly divided into north and 

south ridges by longitudinal valleys; the middle part of these mountains takes a zigzag course; and the eastern part consists of five 

rather distinct ridges, upon which are several peaks, including Nel6 Griswold, L. S., op. cit.
16

son, Strawn, White, and Sharptop Mountains. Fodderstack Mountain (one of the three of that name in these two quadrangles), an 

outlier of the Caddo Mountains, stands as a conspicuous feature in 

the southern part of the Caddo Basin.

The quadrangles embrace practically the entire group of ridges 

to which the name Cossatot Mountains is applied. This group extends south of east across the northeast corner of the De Queen 

quadrangle, where it joins the Caddo Mountains, and across the 

northern part of the Caddo Gap quadrangle, in which it contracts 

eastward and terminates near the east boundary. Many of the 

ridges slope down into the Cove Basin on the west, others into the 

Athens Plateau on the south, and still others into the Mazarn Basin 

on the north. The middle and western portions of the Cossatot 

Mountains are the highest and most rugged, consisting of a considerable number of ridges and several more or less isolated mountains, many of which rise more than 2,000 feet above sea level. 

Among the most prominent'peaks that exceed this altitude are Eagle, 

Fodderstack, West Hanna, East Hanna, Nichols, Katy, and Buckeye 

Mountains and Tall Peak, in the De Queen quadrangle; Sugartreer 

Brushheap, and Fodderstack Mountains, in the Caddo Gap quadrangle; and McKinley Mountain and Kaspberry Peak, lying partly 

in both quadrangles. Kaspberry Peak, the highest of these, is 2,360 

feet above sea level.

The ridges of the Caddo and Cossatot Mountains decrease in width 

and height toward the north in the De Queen quadrangle. This is 

due to the northward thinning of the basal, massive part of the 

Arkansas novaculite, which usually forms their crests.

The Cross Mountains, in the western part of the De Queen quadrangle, are the east end of a prominent group of mountains, the 

greater part of which is included within the Lukfata quadrangle. 

They consist of a few eastward-trending ridges, which in the De 

Queen quadrangle overlook the Cove Basin on the north and terminate on the east in the Athens Plateau. The northernmost ridges 

extend farthest east, whereas Sam Williams Mountain and other 

near-by mountains do not reach the Oklahoma-Arkansas line. 

Whisky Peak, their highest point, is 1,680 feet above sea level.

The topography of all parts of the Cross, Caddo, and Cossatot 

Mountains is of much the same type, but that of the Crystal Mountains is somewhat different, as the ridges of the Crystal Mountains 

are more massive, the slopes less uniform, and the crests not so sharp.

The greater portion of the Caddo Basin is in the Caddo Gap quadrangle and is limited on the east by the Crystal Mountains and on 

the south by the Caddo Mountains. Near the Caddo Mountains it 

exhibits a foothill topography consisting of low ridges upon which 

there are many dome-shaped knobs, the slopes of both knobs and
GEOGRAPHY 17

ridges being steep and thickly covered with rock debris. Farther 

north the topography of the basin is gently rolling, the interstream 

areas are irregular, with the exception of a few short ridges, and 

the general surface ranges from 700 jto 900 feet above sea level.

The comparatively wide valley between the Caddo and Cossatot 

Mountains in the Caddo Gap quadrangle is the west end of the 

Mazarn Basin, a large part of which is situated' in Montgomery and 

Garland Counties, Ark., east of the quadrangle. With the exception of a single low ridge on the east border northeast of Glenwood, 

the topography of the part of the basin embraced in the quadrangle 

is gently rolling. The interstream areas are irregular in form, and 

the usual altitudes are between 500 and 1,000 feet above sea level, 

being highest to the west.

Much of the southeastern part of the Cove Basin lies in the northwest corner of the De Queen quadrangle, and in it are situated the 

villages of Hatfield, Cove, and Vandervoort. The basin takes its 

name from Cove. This, part of the basin is bordered on the south by 

the Cross Mountains and on the east by the Cossatot Mountains and 

Athens Plateau. It is dissected by many valleys. The interstream 

areas consist in part of irregular hills but mainly of flat, low ridges 

with an eastward trend. The crests of the hills and ridges reach a 

common level, which ranges from .1,100 to 1,250 feet above sea level.

The Athens Plateau lies mostly in the quadrangles herein described. It is dissected by several narrow, crooked valleys of southward-flowing trunk streams and by numerous east-west valleys of 

small tributary streams. The interstream areas are eastward-trending ridges, of which the broadest and most prominent are in the 

Caddo Gap quadrangle. Water gaps are common, but they are less 

conspicuous than in the mountainous area because the ridges are not 

so high. The upland surface of this area ranges from 750 to 1,100 

feet above sea level, being highest at the north, and the valleys of 

the larger streams that trench it are about 350 feet deep. The 

plateau is more fully described on pages 7-8.

The part of the West Gulf Coastal Plain that is included in the 

quadrangles extends along their southern boundary and ranges from 

5 to 10 miles in width. The difference between the topography of 

this belt and that of the Athens Plateau is striking. This part of the 

quadrangles has a gently undulating surface consisting of shallow 

valleys, of rather wide alluvial bottoms bordered by remnants of 

terraces along the larger streams, and of hilly, irregular interstream 

areas. Most of this area is between 400 and 600 feet above sea level. 

In the Caddo Gap quadrangle there is a southward-sloping plateaulike area or cuesta, which is best preserved from erosion between 

Murfreesboro and the southwest corner of the quadrangle, where 

most of its surface is from 500 to 700 feet above sea level; but south-
18 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

east of Murfreesboro the streams that formerly flowed down its 

southern slope have cut its surface into north-south ridges. This 

plateau extends westward across the extreme southeast corner of the 

De Queen quadrangle and continues farther west just south of that 

quadrangle. The plateau is formed by resistant southward-dipping 

gravel beds of Cretaceous age and is what Veatch 7 describes as the 

Lockesburg Wold.

The character of the surface differs greatly in the different parts 

of the quadrangles. The basin areas, the Athens Plateau, and the 

West Gulf Coastal Plain are nearly everywhere gently rolling, though 

there are many steep hill slopes, and a few low cliffs rise from the 

streams, most of them standing on the outside of the stream bends. 

The level tracts and the more gentle slopes are mantled with residual 

soil or wash from the higher ground. Rock outcrops are common 

and are especially abundant on the steeper slopes, in road cuts, and 

in stream beds.

In the mountainous areas the surface is- very rough, the slopes 

are steep, and rock ledges are numerous. There are, however, no 

large surfaces of bare rock except along the crests of some of the 

higher ridges and in the water gaps, and there are not many cliffs.. 

One of the best-known ledges of rock in west-central Arkansas is. 

Standing Rock, which is on Board Camp Creek, in the De Queen 

quadrangle. This rock is formed by a vertical bed of the Arkansas 

novaculite 3 to 6 feet thick and rises like a wall of masonry to a 

height of 75 feet above the creek. (See pi. 2.) The slopes, wherenot occupied by bare ledges, are covered by talus, much of which 

consists of boulders. This material collects in large quantities on 

the slopes, but the most favorable places are the heads of steep-sided.

ravines, where the loose rock forms barren talus slopes.

DRAINAGE

Nearly all the drainage of the Caddo Gap and De Queen quadr.angles flows southward into Ouachita and Little Rivers, which, in. 

turn, empty into Red River, Little River entering it in Arkansas, and 

the Ouachita entering it near its mouth in Louisiana.

The principal streams in the Caddo Gap quadrangle are Caddoand Little Missouri Rivers, both of which join Ouachita River. Of 

these two Little Missouri River is the larger. It rises south of .the 

Missouri Mountains, takes a southward course, and after passing 

through the Cossatot Mountains, across the Athens Plateau, and into 

the Coastal Plain leaves the quadrangle on the south side. It receives many small tributaries, among which are Long, Blaylock, and 

Hurricane Creeks and Muddy Fork, from the west; and Blocker,

7 Veatch, A. C., Geology and Underground Water Resources of Northern Louisiana andi 

Southern Arkansas : U. S. Geol. Survey Prof. Paper 46, 1906.
GEOGRAPHY 19

Self, Bear, and Prairie Creeks, from ,th*e east. Caddo River rises 

north of the Missouri Mountains, runs eastward and southeastward, 

passing through the Caddo Basin, the Caddo Mountains, and Mazarn 

Basin, in the order named, and leaves the quadrangle at the east end of 

:he Cossatot Mountains. Its principal western tributaries are Polk 

and Mill Creeks and South Fork and its eastern branches are Lick and 

Collier Creeks. The upper 12 miles of the stream runs parallel with 

;he ridges, and the remainder runs transverse to them, but the only 

notable water gap formed is Caddo Gap, where the stream passes 

;hrough Caddo Mountains. This is one of the most conspicuous and 

probably the best-known water gap in the Ouachita area, and from it 

the Caddo Gap quadrangle derives its name. Big Fork Creek, in 

;he northwestern part of the quadrangle, flows northward into 

Ouachita River; Mazarn Creek, in the northeast corner, flows eastward and joins the same river; Antoine Creek, which heads in the 

iastern part of the quadrangle, receives the waters of Bigsby, Woodall, Caney, and Wolf Creeks and joins Little Missouri River south 

of the quadrangle; Simpkins, Saline, Vaughn, and Clear Creeks, in 

;he southeast corner, also empty into Little Missouri River; and 

3rushy. Holly, Messer, and other small creeks in the western part 

of the quadrangle, as well as most of the southward-flowing streams 

that drain the plateau southwest of Murfreesboro, join Saline River. 

The larger streams in the De Queen quadrangle are Saline River, 

Cossatot River, Rolling Fork, and Mountain Fork of Little River, 

which join Little River farther south. Saline River rises in the 

Cossatot Mountains and after flowing southward across the Athens 

Plateau and into' the Coastal Plain leaves the quadrangle on the 

south side. Between 2 and 3 miles of its upper course lies in the 

Caddo Gap quadrangle. Among its tributaries are Brushy, Caney, 

Holly, and Messer Creeks from the east, and Camp, Snake, Panther, 

and Shepherd Creeks from the west. Cossatot River heads in the 

mountains in the northeast corner of the quadrangle, finds its way 

through the Cossatot Mountains by passing through several deepcut water gaps, and flows southward across the Athens Plateau and 

into the Coastal Plain, receiving in its course Mine, Sugar, Caney, 

Harris, and Hale Creeks and other small streams from the east and 

Brushy, Flat, Cow, Opossum, Coon, and Buck Creeks and other 

small streams from the west. Rolling Fork rises in the east end of 

the Cross Mountains, flows southward, passing across the Athens 

Plateau and into the Coastal Plain, and leaves the quadrangle on the 

south side, after receiving Robinson Creek and smaller streams. It 

is joined outside the quadrangle by Bear and Rock Creeks, which 

drain a part of the southwest corner of the area. Mountain Fork 

of Little River runs south of west through the extreme northwest
20 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

corner of the quadrangle.. 'Its tributaries, whose courses lie partly ii 

the quadrangle, are Twomile, Joshling, Sixmile, Dry, and BuffaL 

Creeks. They drain most of the part of Cove Basin embraced in th< 

area. Board Camp Creek, with its tributary, Macks Creek, drains 

small part of the mountainous region in the northeast corner of th( 

quadrangle and enters Ouachita River on the north.

An interesting feature of the topography of the mountainous ares 

is the great number of water gaps formed by Caddo, Little Missouri 

and Cossatot Rivers and smaller streams. The Little Missouri flow 

through no less than seven and the Cossatot no less than five; there 

are at least 17 in the Caddo Gap quadrangle and 20 in the De Queer 

quadrangle. Most of these gaps are rocky, narrow gorges through 

the ridges, with only room enough beside the streams for trails.

In much of the Athens Plateau and the Ouachita Mountains the 

streams might well be divided into tAvo classes those whose course 

run parallel with the ridges and those that flow across the trend o 

the ridges. The latter class includes the trunk streams, which are 

joined almost at right angles by many of their tributaries. ThL 

arrangement of the streams, which is illustrated in Plate 1, is com 

monly known as the " trellis" system of drainage. This type o 

drainage is the result of the partial adjustment of an ancient drain 

age to the structure of the rocks, the trunk streams having intrenche< 

their courses across the strike of the rocks, and many of their tribu 

taries having cut their valleys wholly in the more easily eroded strata 

The streams in the West Gulf Coastal Plain illustrate a consequen 

drainage, as they have a general southward course that is the same 

as the dip of the rock formations. (See pi. 1.)

Most of the streams are perennial and are supplied with watei 

from springs in all parts of the area. They can be easily forded 

throughout much of the year but are subject to sudden rises after 

heavy rains.

In the Athens Plateau and the Ouachita Mountains the streams 

are rather swift, forming numerous riffles and rapids separated by 

quiet reaches, and flow in narrow valleys containing only small strips 

of flood-plain deposits; but on reaching the Coastal Plain the streams 

become sluggish and the valleys widen and contain considerable areas 

of alluvial deposits. The rapids are found in many of the water 

gaps. In some water gaps there are low waterfalls, noteworthy 

among which is that of Little Missouri River just north of the 

Montgomery-Pike County line, that of the same stream just west of 

Round Mountain, and that of Cossatot River about 2 miles northwest of Duckett post office. The north-south streams in the Athens 

Plateau, although their valleys are marrow, their* currents swift, and 

their flood-plain deposits meager, have courses as crooked as those
TJ. S. GEOLOGICAL SURVEY BULLETIN 808 PLATE 2

STANDING ROCK, ON BOARD CAMP CREEK, ARK.

The rock, 75 feet high, is formed by a vertical bed of the Arkansas novaculite, 3 to 6 feet thick. 

Photograph by Bert Hiltebrand
GEOGRAPHY 21

of the sluggish streams in the Coastal Plain, wjiich flow through 

wide areas of alluvium. The meanders on the Athens Plateau are 

apparently intrenched, the streams having originally flowed in 

crooked channels on a cover of Cretaceous sediments, and later as 

they lowered their beds they incised their courses in the hard upturned Paleozoic strata. The size of the bends, however, is not 

wholly attributable to this cause. The surface on the inside of the 

bends slopes more or less gradually down to the present stream bed, 

whereas on the outside of the bends the descent to the stream is 

everywhere steep and in many places vertical. This indicates that 

the crookedness of the streams has increased as they have gradually 

deepened their valleys. The history of the streams is discussed more 

fully under "Geologic history" (pp. 143-146).

CULTURE

The area is not densely populated, but only the most mountainous 

parts are without houses. The rural population, most of which is 

engaged in agriculture, is sparse except in the level or gently rolling upland and valley areas where there is the greatest quantity 

of tillable land. The largest town is De Queen, the county seat of 

Sevier County. Among the villages and other towns of less size 

are Hatfield, Cove, Vandervoort, Wickes, Grannis, Gillham, and 

Dierks, in the De Queen quadrangle; and Murfreesboro, the county 

seat of Pike County, Center Point, Delight, Rosboro, Glenwood, 

Caddo Gap, and Womble, in the Caddo Gap quadrangle. All these 

places except Center Point are on railroads.

The main line of the Kansas City Southern Railway traverses 

from north to south the west half of the De Queen quadrangle. 

The Texas, Oklahoma & Eastern Railroad runs west from De Queen 

through Broken Bow to Valliant, Okla. The De Queen & Eastern 

Railroad extends from De Queen as far east as Dierks, though a few 

miles of its track lies south of the quadrangle. The railroad shown 

on the De Queen topographic map, running southeast from Dierks, 

and the line south of that place, which crosses Messef Creek and 

extends into Center Point Township, are merely lumber roads. Two 

branches of the Missouri Pacific Railroad enter the east side of the 

Caddo Gap quadrangle, one extending to Pike and the other to 

Womble. These two lines unite at Antoine, east of the quadrangle, 

and farther east, at Gurdon, Ark., join the main line of that railroad connecting St. Louis and Texarkana. The Caddo & Choctaw 

Railroad formerly extended from Rosboro westward to Cooper Junction, but its use has been discontinued. The Murfreesboro-Nashville 

Southwestern Railway, formerly the Memphis, Dallas & Gulf Rail6242 29 3
22 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

road, traverses the southeastern part of the Caddo Gap quadrangle, entering at the south side near Tokio, Ark., and passing 

northeastward to Murfreesboro. This railroad formerly ran northeastward from Murfreesboro to the east bor'der of the quadrangle. 

After leaving the quadrangle on the east side it joined the Missouri 

Pacific Railroad at Shawmut, Ark., used the track of that road from 

Shawmut to Glenwood and thence extended northeastward to Hot 

Springs. The part of the railroad between Murfreesboro and 

Hot Springs, however, is no longer used. The Prescott & Northwestern Railroad enters the Caddo Gap quadrangle at Tokio and runs 

as far as Highland.

Several main highways cross the quadrangles, and other roads 

that are less well maintained reach all parts of the area. On account 

of the character of the topography few of the roads follow sectioji 

lines. In the mountainous districts they keep to the valleys and cross 

the mountains only where there are water gaps or saddles. Some 

main highways as well as trails penetrate the roughest, most scenic 

parts of the country, much of which is included in the Ouachita 

National Forest, formerly called the Arkansas National Forest.

Agriculture is the chief occupation in the quadrangles, the soil 

and climate of which are adapted to general farming, fruit growing, 

and grazing, but lumbering is carried on at many localities. Large 

lumber mills are now in operation at several towns, and small mills 

are located at numerous places. Very little mining is done, but 

the minerals mined include quartz crystals in the Crystal Mountains, 

antimony ore near Gillham, and diamonds near Murfreesboro.

DESCRIPTIVE GEOLOGY

STRATIGRAPHY 

GENERAL FEATURES

The exposed rocks of the Caddo Gap and De Queen quadrangles 

are of sedimentary origin, though there are igneous rocks in four 

small areas near Murfreesboro. The igneous rocks are of the single 

kind known as peridotite and were probably intruded while the 

earliest Upper Cretaceous sediments exposed in the quadrangles 

were being laid down. The sedimentary rocks exhibit considerable 

diversity, consisting of clay, sand, marl, shale, slate, chert, gravel, 

limestone, sandstone, tuff, novaculite, and conglomerate. They are 

grouped into 16 formations, whose distribution is shown on Plate 3. 

The aggregate of the minimum thicknesses of the formations is 

21,720 feet, and the aggregate of their maximum thicknesses is 26,875 

feet. The sequence, thickness, and diverse character of the beds
Various classifications of formations of Paleozoic age exposed in the Ouachita Mountain region of Arkansas and Oklahoma

Caddo Gap and De Queen quadrangles, 

Ark.-Okla.

Carboniferous.

sylvanian.

a 

a<o

PH

Mississippian.

Atoka formation.

[Not present.]

Jack fork sandstone.

Stanley shale.

[Not present.]

t> 

Q

Devonian.

<i> 

*5

d>

£Q

Middle Devonian.

d 

.2 

j3

CO

Ordovician.

^dc*- c3

n!§ 2 > O.O

S|

Middle Ordovician.

Lower Ordovician.

">c^

 S3

0°

i| o£

Arkansas novaculite.

Missouri Mountain slate.

Dlaylock sandstone.

Polk Creek shale.

Bigfork chert.

Womble shale.

Blakely sandstone.

Mazarn shale.

Crystal Mountain sandstone.

Collier shale.

i

Ouachita geosyncline, Okla. and Ark.

Ulrich, E. O., Fossiliferous boulders in the 

Ouachita "Caney" shale and the age of 

the shale containing them: Oklahoma 

Geol. Survey Bull. 45, 1927.

Pennsylvanian.

Mississippian.

Devonian.

Silurian.

Ordovician.

00

1

14

O

Atoka formation.

Johns Valley shale.

Jackfork sandstone.

Stanley shale.

Upper Arkansas novaculite.

Middle Arkansas novaculite.

Lower Arkansas novaculite.

Missouri Mountain slate.

Blaylock sandstone.

Polk Creek shale.

Bigfork chert.

Stringtown or Womble shale.

Blakely sandstone.

Mazarn shale.

Crystal Mountain sandstone.

Collier shale.

Ouachita Mountains, Okla. and Ark.

Miser, H. D., and Honess, C. W., Age 

relations of the Carboniferous rocks of 

the Ouachita Mountains of Oklahoma and 

Arkansas: Oklahoma Geol. Survey Bull. 

44, 1927.

g Atoka formation.

a 

$

 £ Wapanucka limestone.

§

&4

Caney shale.

a

s 

s

§ Jackfork sandstone.

 § g

0 n

1 

1=5 Stanley shale.

Hot Springs sandstone.

[Not described].

Ouachita Mountains, Okla.

Miser, H. D.. Geologic map of Oklahoma, 

U. S. Geol. Survey, 1926.

Carboniferous.

Devonian?

Devonian.

Silurian.

Ordovician.

°>«- 

 §§ 

0°

agoS'C

O.Q

Pennsylvanian.

Mississippian.

Atoka formation.

1

Wapanucka limestone.

|

Caney shale.

Jackfork sandstone.

Stanley shale.

[Not present.]

Arkansas novaculite.

Missouri Mountain slate.

Blaylock sandstone.

Polk Creek shale.

Bigfork chert.

Womble schistose sandstone.

Blakely sandstone.

Mazarn shale.

Crystal Mountain sandstone.

Collier shale.

Hot Springs district, Ark.

Purdue, A. H., and Miser, H. D., U. S. 

Geol. Survey Geol. Atlas, Hot Springs 

folio (No. -215). 1923.

Carboniferous.

Devonian?

Devonian.

Silurian.

Ordovician.

- [No

Mississippian.

(?) Upper Devonian.

(?) Lower Devonian.

^-.d C-.3

!> 

IS&0

Middle Ordovician.

Lower Ordovician.

Stanley shale.

Hot Springs sandstone.

Arkansas novaculite.

Missouri Mountain shale.

Blaylock sandstone.

Polk Creek shale.

Bigfork chert.

Womble shale.

Blakely sandstone.

Mazarn shale.

exposed.]

Southern Ouachita Mountains, Okla.

Honess, C. W., Geology of the southern 

Ouachita Mountains of Oklahoma: Oklahoma Geol. Survey, Bull. 32, 1923.

d 

a

a> 

S§ fW

§

Carbonif 

Pennsylvanian?

Jackfork sandstone.

Stanley shale.

'Not present.]

Devonian.

d

.2 *c

=5 

03

Ordovician.

la O.2 0°

Is 52

Arkansas novaculite.

Missouri Mountain slate.

Blaylock sandstone.

Polk Creek shale.

Bigfork chert.

Womble schistose sandstone.

Blakely sandstone.

Mazarn shale.

Crystal Mountain sandstone.

Collier shale.

Caddo Gap quadrangle, Ark.

Purdue, A. H., The slates of 

Arkansas: Arkansas Geol. Survey, 1909.

Carboniferous.

unknown. Age 

Jovician.

0

a o 

§1

H

Atoka formation. .

[Not present.]

Jackfork sandstone.

Stanley shale.

Fork Mountain slate.

[Not present.]

Arkansas novaculite.

Missouri Mountain slate.

Blaylock sandstone.

Polk Creek shale.

Bigfork chert.

Stringtown shale.

Ouachita shale.

Crystal Mountain sand 

stone.

Collier shale.

Southeastern Oklahoma

'aff, J. A., Grahamite deposits of 

southeastern Oklahoma: U. S. 

Geol. Survey Bull. 380, pp. 286- 

297, 1909.

Carboniferous.

Atoka formation.

Caney shale.

Jackfork sandstone.

Standley shale.

Not present.]

Ordovician.

Talihina chert

i

Devonian 

and Silurian chert and 

black shale.

Stringtown shale 

? ....

[Not exposed in area of grahamit 

deposits.]

Ouachita Mountains in Atoka 

quadrangle, Okla.

Tafif, J. A., U. S. Geol. Survey 

Geol. Atlas, Atoka folio (No. 

79), 1902.

Ordovician.

rackfork sandstone.

Standley shale.

[Not present.]

Talihina chert.

Stringtown shale. 

 ? 

[Not exposed.]

outhern Ouachita Mountains, Ark.

Griswold, L. S., Whetstones and 

the novaculites of Arkansas: 

Arkansas Geol. Survey Ann. 

Kept, for 1890, vol. 3, pp. 205- 

206, 1892.

Carboniferous. Lower 

Silurian. Lower 

Sandstones and shales.

Novaculites.

"Shales, limestones, massive 

quartzose sandstones, cherty 

blue limestones, with gray, 

black, and yellow shales 

at the bottom."

"Canadian. 6242 29. (Face p. 22.)
STRATIGRAPHY 23

of the formations are graphically represented in the columnar sections on Plates 4 and 5. From their fossil content, lithologic character, and stratigraphic position they are placed in the Cambrian, 

Ordovician, Silurian, Devonian, Carboniferous, Cretaceous, and 

Quaternary systems. The age assignments and formation names 

given to the Paleozoic rocks from time to time as knowledge of the 

Ouachita Mountain region has increased are shown in the accompanying correlation table.

CAMBRIAN SYSTEM 

COLLIER SHALE

Definition. The Collier shale received its name from Collier Creek, 

in the Crystal Mountains in the Caddo Gap quadrangle, along whose

headwaters it was first observed by the authors. It is the lowest and 

consequently the oldest exposed formation, not only in these quadrangles but in the whole Ouachita Mountain region, and according 

to evidence stated on page 24 it is believed to belong to the Cambrian system. As the name implies, the formation consists principally of shale, but it contains some limestone and a meager amount 

of chert. The thickness that is exposed in the Caddo Gap quadrangle is 200 feet, but much more, probably several hundred feet, is 

exposed in the adjoining Mount Ida quadrangle, on the north.

Distribution. The outcrops of the Collier shale in the Caddo Gap 

quadrangle occur in the Crystal Mountains, where they form narrow 

belts in valleys or on steep slopes.

Character. The bulk of the formation is bluish-black soft graphitic clay shale. Owing to the severe squeezing and shearing that 

the shale has undergone, it is intensely crumpled, is full of glossy, 

slickensided surfaces, and has lost practically all traces of bedding. 

In places slaty cleavage may be observed. Thin and widely separated beds of black, dense, and much fractured chert are found in 

some exposures, and fragments from them are seen here and there on 

the surface. The upper 100 feet or more of the shale contains a considerable quantity of dark finely crystalline limestone, some of which 

occurs in lenses and layers half an inch or more thick distributed 

through the shale. In the lower parts of the shale the limestone is 

about 100 feet thick and occurs in much contorted layers from a 

few inches to more than 2 feet thick, interbedded with thin seams of 

graphitic shale. These layers are light steel-gray to bluish gray or 

black, the lighter colors predominating at the top and the darker at 

the base. All the limestone, however, is compact, much jointed, and 

brittle, contains many thin veins of white calcite, and becomes dark 

blue on weathered surfaces.
24 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Age and stratigraphic relations. The Collier shale is overlain by 

the Crystal Mountain sandstone, and this in turn by the Mazarn 

shale. The Mazarn shale is known from its fossils to belong to the 

Lower Ordovician series. The Crystal Mountain sandstone, on 

account of its lithology and stratigraphic relations, is referred to the 

same series, though the reference is doubtful, as no fossils have been 

found in the sandstone. The Collier shale has yielded no fossils, and 

it has no lithologic features that would give it claim to an age classification with the higher rocks. A conglomerate at the base of the 

overlying sandstone is of such a character that it establishes an 

unconformity at this horizon. The Collier shale is therefore classified 

as Cambrian.

ORDOVICIAN ( ?) SYSTEM 

CRYSTAL MOUNTAIN SANDSTONE

Definition. The Crystal Mountain sandstone received its name 

from the Crystal Mountains, most of which are formed by this sandstone. It is composed almost entirely of sandstone, is 850 feet thick, 

and is doubtfully referred to the Lower Ordovician series.

Distribution. This formation is exposed only in the Crystal Mountains. Its exposures are narrow east-west belts, and they produce 

high rugged ridges on which many rock ledges protrude through a 

surficial mantle of huge boulders and finer material. The best 

exposures are on the headwaters of Collier Creek.

Character. Besides sandstone the formation contains a thin basal 

conglomerate and a very subordinate quantity of shale. The sandstone is massive and coarse grained and is composed of well-rounded, 

translucent quartz grains, cemented together in some beds by calcium

carbonate but in most beds by silica. The calcareous beds are brown 

and become rather friable on weathering, but the siliceous sandstone 

is light gray, is hard and dense, and breaks into large and small 

blocks that cover much of the surface. Joints in the sandstone are 

abundant, and they are so even and nearly parallel in many places 

that their surfaces may be mistaken for bedding planes.

Much of the sandstone is cut with a network of veins of white 

quartz from a fraction of an inch to several inches thick. In many 

places beautiful clusters of quartz crystals both milky and transparent line the walls of fissures, which range from several inches to 

several feet wide. (See pi. 17, B.) The Crystal Mountains received 

their name from the abundance of these crystals. The large number 

of quartz crystals that are sold at Hot Springs, Ark., for museums 

and private collections are obtained from this sandstone. The principal crystal mines in the Caddo Gap quadrangle are on Collier Creek.
STRATIGEAPHY 25

The basal conglomerate reaches a thickness of 10 or 12 feet and 

has an earthy, calcareous matrix, in which there are rounded quartz 

grains reaching the size of peas and rounded and subangular pebbles 

and cobbles of bluish limestone and black chert as much as 6 inches 

in diameter. The limestone and chert pebbles are identical in character with the limestone and chert in the Collier shale, and for this 

reason there seems no doubt that they were derived from that formation. Where the more sandy parts of the conglomerate are weathered they resemble in places soft, coarse, brown, porous sandstone.

,The small quantity of shale interbedded with the sandstone is a 

black clay shale, but in places there are thin alternating layers of 

a greenish color.

Age and stratigrapMc relations. The Crystal Mountain sandstone 

has not yielded any fossils. It is unconformably underlain by the

Collier shale and is overlain by the Mazarn shale, of Lower Ordovician age, from which it is not separated by any indication of a 

stratigraphic break. The shale interbedded with the upper part of 

this sandstone closely resembles the basal portion of the Mazarn 

shale. This resemblance is so strong that to the observer in the field 

it appears to be conclusive evidence that the Crystal Mountain sandstone and Mazarn shale belong to the same series Lower Ordovician though the reference of the sandstone to this series can not 

be definitely made on account of the absence of fossils in the 

sandstone.

ORDOVIOIAN SYSTEM 

MAZARN SHALE

Definition. The Mazarn shale is composed chiefly of shale with 

subordinate amounts of sandstone and limestone and is of Lower 

Ordovician age. It received its name from Mazarn Creek, whose 

headwaters are in the northeast corner of the Caddo Gap quadrangle. 

The shale to which this name is'now applied was in 1909 regarded 

by Purdue as a part of his " Ouachita shale," which as defined comprised the rocks between the Crystal Mountain sandstone below and 

the Stringtown shale above. A sandstone now called the Blakely 

sandstone, which was in 1909 8 regarded as the upper part of the 

Crystal Mountain sandstone, has since been determined by the 

authors to occur in the middle of the " Ouachita shale." The use 

of the name Stringtown has been discontinued in this area because 

the beds to which it was applied do not form a mappable unit distinct from the rest of the shale above the Blakely sandstone, and 

because the graptolites supposed to be characteristic of it have

8 Purdue, A. H., The Slates of Arkansas, pp. 30, 33-35', Arkansas Geol. Survey, 1909; 

(abstract) U. S. Geol. Survey Bull. 430, pp. 321-325, 1910; (abstract) U. S. Geol. Survey 

Prof. Paper 71, pp. 160-162, 1912.
26 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

apparently been found well down in the underlying shale. The 

recognition of the Blakely sandstone as a distinct formation and 

the failure to separate the Stringtown made it necessary to give 

a new name (Womble shale) to the whole group between the Blakely 

sandstone and the Bigfork chert. It was also necessary to give a 

new name (Mazarn shale) to the shale between the Blakely and 

Crystal Mountain sandstones. The name " Ouachita shale" is 

abandoned because its limits are not the same as those of any one 

of the units now mapped and because Ouachita has the same pronunciation as Washita, the well-established name of the upper group 

of the Comanche series.

The Mazarn shale is apparently conformable with both the underlying Crystal Mountain sandstone and the overlying Blakely sandstone. The occurrence of a conglomerate in places at the base of the 

Blakely sandstone in Blakely Mountain, in the northwest corner of 

the Hot Springs district,9 which is east of the area herein described, 

suggests the presence of an unconformity at this horizon in that district. No conglomerate was observed at the base of the sandstone in 

the Caddo Gap quadrangle.

Distribution and character. The Mazarn shale is exposed in the 

Caddo Gap quadrangle but not in the De Queen quadrangle. It is 

the surface rock in the valley just north of the ridge running east 

from Womble and at places in the high ridges of the Crystal Mountains on the north. West of these mountains its exact area! extent is 

unknown, because the shale can not there be distinguished from the 

shale of the Blakely sandstone nor from the Womble shale. The 

sandstone in the Blakely thins out at Womble and is present at only 

one place west of that town.

The Mazarn consists predominantly of shale, although in places it 

contains small quantities of limestone and sandstone. The thickness 

is roughly estimated to be 1,000 feet. Much of the shale is black, 

clayey, and fissile, but other parts' consist of alternating black and 

green layers, the latter commonly about 1 inch thick. Straight, welldefined joints dissect most of the shale, and slaty cleavage, at an 

angle to the bedding, is developed at many localities. In these places 

the differently colored layers produce ribboned slate, exposures and 

small blocks of which are especially numerous along the streams. 

(See pi. 6, A.) The limestone is apparently near the middle of the 

shale. It is dark blue on weathered surfaces and black on freshly 

fractured surfaces; it is compact, thin bedded, finely crystalline, and 

nonmagnesian; it occurs in beds probably not more than 10 or 15 feet 

thick; and it is interbedded with shale like that above and below.

 The Hot Springs district, described by the authors in U. S. Geol. Survey Geol. Atlas, 

Folio 215, comprises a part of the Hot Springs and Benton quadrangles and of two 

unnamed quadrangles.
STEATIGEAPHY 27,

Some of the limestone is a sandy conglomerate containing minute 

limestone pebbles. Sandstone, although in small quantity, is found 

in many places. It is gray, hard, laminated, fine grained, and 

quartzitic and occurs in thin layers some of which reach 2 feet in 

thickness.

Many thin veins of white quartz and some white calcite showing a 

comb structure at places cut the shale, sandstone, and limestone in all 

directions, and in some of the more level areas underlain by shale the 

residual quartz has collected in sufficient quantities to make the surface white. A boulder of folded laminated sandstone containing 

quartz veins that were broken by the shearing of the layers was observed loose on the surface, though probably not far from the parent 

ledge in the lower part of the formation. The shearing of the layers 

and the breaking of the quartz veins were caused by the folding of

the sandstone. The folding of this sandstone and of the other rocks 

of the Ouachita Mountains took place near the middle or late in the 

Pennsylvanian epoch. From these facts the conclusion is. drawn 

that at least some of the quartz veins of the Ouachita Mountains 

were formed before Pennsylvanian time. Evidence has been found 

in the fuller's earth mines at Klondike, in Saline County, Ark., east 

of these quadrangles, showing that some of the quartz veins of the 

Ouachita Mountains were formed after the folding of strata, but 

before the intrusion of the igneous rocks of these mountains in the 

Cretaceous period.

Fossils and correlation. Fossils are rare in the Mazarn shale. 

Most of those that have been collected in the Mazarn as well as in 

younger formations of Ordovician age in this region are graptolites, 

which may as a rule be looked for only in black shale that .splits into 

slabs with smooth surfaces parallel to the bedding. On such surfaces 

the graptolites appear like delicate white pencil markings, usually 

toothed like a saw on one or both sides.

Two collections have been made from the shale near Womble, in 

the Caddo Gap quadrangle, and another at a locality 12 miles' west 

of Little Kock, Ark. The larger one of the collections near Womble 

was obtained in the N. % sec. 22, T. 3 S., R. 25 W., about 2 miles 

northeast of the town. It has furnished specimens which are recognized by Ulrich as follows: 10

Didymograptus nitidus Hall. 

Didymograptus extensus Hall. 

Didymograptus similis Hall. 

Didymograptus filiformis Tullberg. 

Tetragraptus amii Lapworth. 

Tetragraptus approximatus Nicholson.

10 Ulrich, E. O., Revision of the Paleozoic Systems: Geol. Soc. America Bull., vol., 22, 

p. 677, 1911.
28 Da QUEEN AND CADDO GAP QUADBANGLES, ARKANSAS

Tetragraptus clarkei Ruedemann. 

Tetragraptus fruticosus Hall. 

Tetragraptus cf. T. pendens Elles and Wood. 

Tetragraptus quadribrachiatus Hail. 

Tetragraptus serra Brongniart. 

Tetragraptus similis Hall.

Ulrich points out that 8 of the 12 species just listed occur in the 

Tetragraptws zone and 4 in the Didymograptus bifidus zone in New 

York and Quebec, and that 10 are listed by British authorities from 

the Lower Arenig and Middle Skiddaw slates of Great Britain.

The collection from the locality 12 miles west of Little Rock is said 

by Ulrich to occur at a higher zone in the formation. It includes the 

following species which have been identified by him: X1

1. Didymograptus euodus Lapworth.

2. Didymograptus caduceus (Salter) Ruedemann.

3. Didymograptus caduceus nana Ruedemann.

4. Didymograptus n. sp. (near D. forcipiformis, but coarser).

5. Tetragraptus quadribrachiatus Hall.

6. Tetragraptus amii? Elles and Wood.

7. Tetragraptus pendens Elles and Wood.

8. Tetragraptus clarkei n. var. (larger).

9. Tetragraptus similis n. var.

10. Phyllograptus typus n. var.

11. Diplograptus sp. undet. cf. D. calcaratus priscus Elles and Wood.

12. Mesograptus sp. undet.

13. Cryptograptus antennarius Hall.

14. Cryptograptus tricornis? Carruthers.

15. Glossograptus hystrix Ruedemann.

16. Retiograptus tentaculatus? Hall.

17. Caryocaris wrighti Salter.

Of these Nos. 5 to 9 are found also in the lower zone, but in each case the 

later occurrence is a distinguishable mutation. The same species, also Nos. 2 

and 10, occur in the Didymograptus bifidus zone in New York and Canada, 

and Nos. 2, 5, 6, 7, and 9 are found in the Skiddaw slates of Great Britain. 

Nos. 3, 4, 5, 13, 15, and 16 that is, most of the Axonophora are found in and 

for the most part confined to the Diplograptus dentatus zone in Ruedemann's 

Deepkill section. However, on account of the strong development of Tetragraptus and the presence of Didymograptus caduceus in this Arkansas fauna I 

regard it as older than the Diplograptus dentatus zone and as approximately 

equivalent to the Ashhill Quarry zone, which Ruedemann places as a " transitional subzone" between the Didymograptus bifidus and the Diplograptus 

dentatus zones.

The Mazarn shale on the basis of the fossils discussed above is 

regarded by Ulrich as being of the same age as the lower part of 

the Beekmantown (Lower Ordovician) limestone of the Appalachian 

region.

11 Ulrich, B. O., op. cit., p. 678.
U. S. GEOLOGICAL SURVEY BULLETIN 808 PLATE 4

System

Carboniferous

Dev.?

h

fi«

.2

U|

CO

Ordovician

Ordovician?

Cambrian

Series

a

1

>>

in

(^

sissippian

.a

S

u.?

Dev.

U. 

Dev.

M. 

Dev.

U.?

Or. 

fiddle Ordovician

Ordovician rer 

3

Formation

Atoka formation.

Jackfork sandstone.

Stanley shale.

Hatton tuff lentil.

Arkansas novaculite.

Missouri Mountain slate.

Blaylock sandstone.

Unconformity? 

?olk Creek shale.

Womble shale. 

Blakely sandstone.

Mazarn shale.

Crystal Mountain sandstone.

Sym 

bol

Ca

Cj

Cs

C.h

Da

Sm

Sb

Obf

Ow 

Oby

Om 

Oc

Section

 _ - - _ _ -* __ 

v/'.-X' ; '/! .' ' '. :ss7-''-:&'-''3%'-'~

- '= 

l^'tt^^ttt:?*:-:

'&£&-^-&:£.:-::'--£L

Sy.-^-.-Tr?.-^-: . 

^m&ztf&L

\yT7-! ~r-v7-r;~;vT;v?7.' -77"

 . __._ _ 

- 

= -=r

JIl'lZZ~lZ^il^:=-r-z^

=HLiil' ' "Jl" '= ' ±= 

 .^T7T..T7Tr..r7T77T.rr^T..-

£:+tt::tw^;$y

^^^ ^V-X-XiX^:!^.

 ' .' ':' ' ' .' ' .' 'Xv'.1 .' '. '. : ; ; ; '/

-- 

vT.'7.-v> ..'.-7.<'vr.v.p .-.v.'77A':"^"

 ~ 

M£M±M£M

lilflll®8

WMiiMM&L

W^£&££h

i^^^ivivi^v-^iVy

-,-:.. ,-, ,--..-

 

 - .

asiiiiiinu-.iaiiv^LaL.-iii"!!.

 

5=ji5g?S^^S5S^

:^:>^v^.v^v:v1 v:..vi.

=^=--=-^=-^=-^=-

..j^^^^p^;;::^

~^^ ^

;;;;ii;;:!;;v.y.y.^;v..V.v.!;;;.v.v;.v.-:;;;;:i:

^.^...^...^^UMSMig^

^^^.^rr.TTrr^.T^-.Trrr.^rr.:^

^y^=4^i=^p2s^= CyS^f^TiMYfr

\'\v''-:V'V^^\\\V\\\'O.Vi. :.v.'.v'.v.'vlv

1 r.''j.'.'i' ,'.',' ,''? '. .'''.' ' '.'.' ', ' ' ' ' '.sfo=*?

-mmmmm

^nzr - i~zr~.^=

=-=j._^_ . -j=

T ' ' ' -^ .' . ' ',","rf"i

 ^^^^=^^f^

~ ^ "I 1 .. ' ' Jr^' ' ^ __' ' IT *

Thickness in 

feet

6,000

5,000- 

6,600

6,000

(0-90)

300-950

50±-300

0-1, 500

0-175

700

1,000 

0-400

1,000 

850

200+

Character of rocks

massive, and thin bedded; some beds near base are coarse grained and 

contain some grit. Shale dark to coal-black; weathers to red clay.

Sandstone, a little shale, and some millstone grit. Sandstone gray, 

fine to coarse grained; mostly quartzitic. Millstone grit containing 

quartz pebbles mostly in basal part of formation. Shale is green 

fissile clay shale.

Mainly shale, with much sandstone and some tuff and conglomerate. 

Shale fissile, bluish black and black in fresh exposures along streams, 

green, yellow, or brown in more weathered exposures along roads. 

Sandstone bard, tough, compact, quartzitic, fine grained, greenish

greenish tinge; contains large grains of feldspar. Conglomerate near 

base is composed of novaculite pebbles in dense siliceous matrix.

Thin-bedded dark novaculite and black shale. 

Massive white novaculite.

Red and green slate.

Hard light to dark gray sandstone and dark shale.

Black fissile carbonaceous shale.

Gray to black even-bedded, much fractured chert, some black shale,

Shale in alternating black and green layers, some blue limestone, and 

a little sandstone.

Sandstone, mostly siliceous and gray, the rest calcareous and bluish 

black, interbedded with shale in black and green layers.

Black and green banded shale, containing thin layers of gray sandstone and lenses of dark-blue limestone.

Massive coarse-grained sandstone; beds with calcareous cement become brown on weathering; beds with siliceous cement are gray.

Bluish-black shale and some limestone.

Character of topography and soil

grazing and in others for general farming.

Low ridges; cultivated in places. Rocky sandy soil, adapted in most 

places for grazing and in a few level areas for general farming.

Low ridges and hills and narrow valleys; cultivated in places. 

Rocky soil, suitable for farming in the more level tracts, in others for

High ridges with steep slopes; rock ledges abound. Scanty soil, suitable for grazing.

Steep slopes or narrow valleys. Rocky soil, suitable for grazing.

Hilly valley areas and steep slopes. Rocky thin soil, suitable for 

grazing.

Rocky slopes and narrow valleys. Thin soil, suitable for grazing.

Steep knobs and low ridges; little cultivated except in stream flats

Low hills and wide valleys. Rocky soil, cultivated in places but 

mostly suitable for grazing.

Sharp ridges; rock ledges abundant. Scanty rocky soil, suitable for 

grazing.

Low hills and wide valleys. Rocky soil, cultivated in places but 

mostly suitable for grazing.

High ridges with steep slopes; rock ledges abound. Scanty rocky 

soil, suitable for grazing.

Narrow valleys and steep slopes. Rocky soil, suitable for grazing.

GENERALIZED SECTION OF THE PALEOZOIC ROCKS EXPOSED IN THE DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS AND OKLAHOMA

0242 29. (Face p. 28.)
U. 8. GEOLOGICAL SURVEY BULLETIN 808 PLATE 5

System

i

e

D

Carboniferous

Series

Gulf (Upper Cretaceous)

Comanche Cretaceous) (Lower 

Formation and member

Brownstown marl.

Tokio 

formation 

(upper part of "Bingen sand" 

of Veatch).

Unconformit

Woodbine 

formation 

(lower part of "Bingen sand " 

of Veatch).

Unconformit

Trinity 

formation.

Unconformit;

Atoka formal 

sandstone, £

y 

y 

De Queen limestone member.

Ultima Thule 

gravel lentil.

Dierks limestone 

lentil.

Pike gravel 

member.

ion, Jackfork 

md Stanley shale.

Section

I1

{

(

(

.vsf.r.vsHiitiitf.VA'AVA'.

ty':&;i^:;&£fr:::':

^^mi^^^i

i^islippii g$ppiflll§i

v.w.v.v.v.*.v.v.v.«.:v.'.

- --=^-=~=^-=r^-=r--=

 -j | ] - - | y=^p

 =^=r=-=-= ====^~,:i3^

= ^n. = 

Jtt#;l;;;SKK-v>:\>;;;;;:

l^fflHiil

mfi''fi-'''''tfffi%'/'ffi''''jffi

Thickness 

in feet

100±

(100-300+)

0-560

(0-72)

70-1,000+ 

(0-40)

(0-40) 

(0-100)

Character of rocks

f Fossiliferous blue or gray 

X calcareous clay.

Gravel; gray cross-bedded quartz sand; lignitic material; volcanic 

ash. light-colored and 

dark clays, some of 

which contain fossil 

plants.

{

Gravel; greenish volcanic 

tuff; red clay; and dark 

plant-bearing clay.

Gray cross-bedded sand 

in heavy beds; some 

clay.

Fossiliferous limestone 

and an equal or greater 

amount of green clay. 

Gypsum and celestite 

near base.

Variegated clays.

f Pebbles less than an inch 

X in diameter.

Variegated clays.

[Fossiliferous limestone 

{ and a smaller amount 

I of green clay.

Gray cross-bedded sand 

in heavy beds; some 

clay.

Irregularly bedded pebbles and cobbles as 

much as 10 inches in 

diameter.

Shale and sandstone.

Character of topography and soil

JGently rolling area. Fertile black waxy soil.

Hilly areas. Gray sandy and gravelly soil; suitable for 

general farming and fruit culture.

[Rolling southward-sloping plateau. Gravelly clay soil 

J suitable for general farming and fruit culture.

All soils mentioned below are suitable for general farming, 

if they are properly cared for.

>Poor gray sandy soil.

Usually a yellowish-brown clay soil; in some areas fertile 

but in others poor.

Dissected southward-sloping upland. Gravelly soil suitable for fruit culture.

[ Fertile black clay soil. 

[Sandy gray soil.

[Dissected southward-sloping upland. Gravelly soil suitI able for fruit culture.

GENERALIZED SECTION OF CRETACEOUS ROCKS EXPOSED IN THE DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS AND OKLAHOMA
U. S. GEOLOGICAL SURVEY BULLETIN 808 PLATE 6

A. " RIBBONED " SHALE WITH HORIZONTAL CLEAVAGE THAT CUTS ACROSS 

BLACK AND GREEN LAYERS

The dip of the layers is high lo the left. Such shale is common in the Mazaril shale, in the Blakcly 

sandstone, and in the lower part of the Womble shale

£. UMKSTOM-; IN WOMBLE SHALE, HALF A MILE SOUTHEAST OF PLATA, ARK.
U. S. GEOLOGICAL SURVEY BULLETIN 808 PLATE 7

A. LOWER DIVISION OF THE ARKANSAS NOVACULITE ON THE EAST SIDE OF 

CADDO HIVER AT CADDO GAP, ARK.

Shows an anticline that, has been broken by two thrust faults. One fault with a dip of about 

90° (shown by slickensides) separates the_ vertical ledge from the beds at the right that dip 

about 45° S. The other fault is in the middle division of the novaculite exposed on the slope 

at the left

S. SANDSTONE IN THE STANLEY SHALE IN A RAILROAD CUT AT VANDERVOORT, ARK.

Rounded boulders of hard, unweathered sandstone are embedded in weathered, friable sandstone

or sand
STRATIGRAPHY 29 

BLAKELY SANDSTONE

Definition. The Blakejy sandstone was named from Blakely 

Mountain, in the northwest corner of the Hot Springs district, 

east of the area herein described. It was first studied by the authors 

in 190T-8 in the Caddo Gap quadrangle, where the principal outcrop 

forms a ridge extending from Womble to the east border of the 

quadrangle. It was then confused with and described as the upper 

part of the Crystal Mountain sandstone. 12 Its true stratigraphic 

place was not determined until 1909, when the field work in the Hot 

Springs district was begun. Earlier determination was prevented 

by the lithologic resemblance of the Blakely to the Crystal Mountain 

sandstone, the identical lithologic character of the underlying 

Mazarn shaje and the base of the overlying Womble shale, and the 

misinterpretation of the structure of the ridge extending eastward 

from Womble that ,is, the conclusion that the structure was a closely 

folded anticline instead of a monocline, which is its true structure.

The Blakely sandstone, as the name implies, contains sandstone, 

which, being very resistant, is the predominant surficial feature, but 

most of the formation ,is shale. The formation is known by its 

fossils to be of Lower Ordovician age. It is conformable with the 

Womble shale above, the two apparently grading into each other, 

and is apparently conformable with the underlying Mazarn shaje. 

A conglomerate that is found at the base in Blakely Mountain, in 

the Hot Springs district suggests the presence of an unconformity 

at the base of the sandstone there. No conglomerate has, however, 

been observed at the base of the sandstone in the Caddo Gap 

quadrangle.

Distribution and character. The principal occurrences of the 

sandstone in the Caddo Gap quadrangle are in the ridge extending 

from Womble eastward beyond the boundary of the quadrangle and 

in two low ridges between Womble and Caddo Gap. The sandstone 

in the small area at Black Springs is mapped as the Blakely, but 

it may be the Crystal Mountain sandstone. The sandstone of the 

Blakely thins out at Womble and is absent west of that place except 

for the possible occurrence at Black Springs. As the shale in the 

Blakely is similar to the Womble and Mazarn shales it can not be 

distinguished from these shales west of Womble. No exposures of 

the sandstone occur in the De Queen quadrangle.

The formation consists of about 400 feet of interbedded shale and 

sandstone, with the shale making probably 75 per cent of the whole. 

Although the sandstone occurs in less amount than the shale, it is so 

resistant that the formation produces ridges. Sandstone layers occur

12 Purdue. A. H.. The Slates of Arkansas, pp. 32-33, Arkansas Geol. Survey, 1909.
30 EE QUEEN AND CADDO GAP QUADBANGLES, ABKANSAS

near the top of the underlying shale and also near the base of the 

overlying shale, and for this reason the upper and lower limits of 

the formation are arbitrarily fixed. The shale is black and argillaceous but contains green bands and is not unlike the Mazarn and 

Womble shales. (See pi. 6, A.) In some if not all places the green 

bands are due to weathering, ,the original color of the rock having 

been black. The sandstone is in beds, most of which are not more 

than 10 feet thick. It is made up of medium-sized, well-rounded, 

translucent quartz grains, firmly cemented together in most beds by 

silica but in the others by calcium carbonate. According to the 

character of the cementing material, there are thus two kinds of 

sandstone, one quartzitic and the other calcareous. The quartzitic 

variety is light to bluish gray, extremely hard, laminated, and 

much jointed, and disintegrates slowly on exposure to the weathering 

agencies. Owing to this character the crests of the ridges are usually 

covered with great heaps of angular boulders, seemingly broken 

from numerous massive beds of sandstone, although in fact the sandstone beds are thin and are separated by thick beds of shale. The 

calcareous sandstone is bluish black and on weathering loses its calcareous material and becomes friable, and gray to brown in color. 

The sandstone is intersected by many quartz veins, most of them less 

than half an ,inch thick, which are so abundant that some of them 

may be seen in most of the ledges and loose boulders.

Fossils cmd correlation. No fossils have been procured from the 

Blakely sandstone in the Caddo Gap quadrangle, but the two following lists supplied by Ulrich show the graptolites that have been 

found in shale near the middle of the sandstone in Blakely Mountain, 

in the Hot Springs district.

Graptolites from shale in the Blakely sandstone in the NE.% sec. 29, T. 1 S., 

R. 20 W. in the Hot Springs district.

Didymograptus sp. 1.

Didymograptus sp. 2.

Didymograptus sp. 3.

Phyllograptus anna Hall.

Phyllograptus cf. P. ilicifolius Hall.

Phyllograptusi cf. P. angustifolius Hall.

Phyllograptus n. sp. (large theca).

Glossograptus echinatus Kuedemann.

Glossograptus horridus.

Diplograptus sp.?

Oyptograptus n. sp.?

Climacograptus?

The following species are from the above locality but 1 foot lower in (he 

shale:

Tetragraptus n. sp. aff. T. quadribrachiatus (Hall).

Tetragraptus cf. T. clarkei (? n. sp.).
STEATIGEAPHY 31

Dichograptus n. sp. 

Didymograptus manus. 

Didymograptus euodes Lapworth. 

Didymograptus spinosus Ruedemann. 

Phyllograptus anna ultimus? 

Diplograptus sp.?

Glossograptus cf. G. hystrix Ruedemann. 

Glossograptus cf. G. echinatus Ruedemann. 

Cryptograptus ? sp.

Ulrich states that the horizon yielding this and the preceding 

collections probably falls between Ruedemann's Phyllograptus zone 

and his next higher zone of Diployraptus dentatus, though doubtless 

nearer the latter than the former.

Other graptolites collected from the same locality as the two just 

mentioned but considerably higher in the Blakely are too poorly

preserved for specific identification, though according to Ulrich they 

are evidently from a different zone from any of the underlying and 

overlying beds represented by collections. The presence of a small 

Phyllog^raptus, perhaps the same as P. anna ultimus Ruedemann, 

indicates, according to him, an alliance with the fauna of the Mazarn 

shale beneath. He therefore concludes that this zone is surely older 

than the Normanskill shale of New York, whose fauna is well represented in the Womble shale above.

The paleontologic evidence just cited indicates that at least the 

lower part of the Blakely sandstone is equivalent to the upper part 

of the Levis shale in Quebec, which is correlated by Ruedemann and 

Ulrich with the Beekmantown (Lower Ordovician) limestone of the 

northern Appalachian region.

WOMBLE SHALE

Definition. The Womble shale is composed of shale and some thin 

beds of sandstone and limestone. It received its name from the town 

of Womble, part of which is on the base of the formation. The 

lower part of the shale to which the name Womble is now applied 

was in 1909 described by Purdue 13 as a part of the " Ouachita shale," 

and the upper part of the Womble shale was described by him as the 

Stringtown shale. The reasons for the discontinuance of these two 

names are given in the description of the Mazarn shale. The Womble 

shale lies conformably above the Blakely sandstone and below the 

Bigfork chert and belongs to the Lower Ordovician series, though 

a bed of Trenton (Middle Ordovician) age exposed at its top in 

the northwestern part of the Caddo Gap quadrangle and at Crystal 

Springs, Ark., has been provisionally included in it.

18 Purdue. A. H., op. cit., pp. 30, 33-35.
32 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Distribution and character. The Womble shale is the surface rock 

over fairly large areas near Caddo Gap, Womble, Black Springs, and 

Big Fork, in the northern part of the Caddo Gap quadrangle, but 

it is nowhere exposed in the De Queen quadrangle. It forms valley 

areas in which there are low, irregular hills. Good rock exposures 

occur at many places, especially along the streams and roads.

The formation is probably about 1,000 feet thick; the thickness 

can not be determined exactly, as the beds are intensely crumpled. 

It consists of shale with some thin beds of sandstone and limestone, 

and much of it closely resembles the Mazarn shale. The shale is 

black, rather hard, and argillaceous and splits into thin pieces when 

struck with a hammer. The green bands are less numerous than 

they are in the Mazarn shale, and as a whole the Womble has a 

somewhat darker aspect than the Mazarn. The upper part is much 

darker than the lower part and contains much carbonaceous matter, 

which blackens the fingers when they are rubbed over freshly 

fractured surfaces. The upper part also contains graptolites in 

abundance. The shale is cut by numerous quartz veins at some 

places. The fragments of white quartz that are residual from these 

veins are so abundant in some areas that they whiten the surface.

Layers of black chert very similar to the Bigfork chert are found 

near the top of the formation at some places. Here and there the 

upper 50 to 75 feet of the formation consists of a porous, tough, finegrained siliceous rock of low specific gravity, in layers from 2 to 4 

inches thick. This variety of rock is dissected by numerous straight 

joints and ranges from gray to pink and bluish in color. Exposures 

of it occur in only a few places, but small blocks are common in the

debris on the slopes. Its origin is not known, but it was probably

formed by the weathering of a calcareous chert or siliceous shale, 

the calcareous material having been removed in solution.

Some sandstone is present in all parts of the formation. It is 

hard, compact, bluish green, quartzose, and fine grained and weathers 

gray or brown.

The limestone occurs as sporadic lenses in the upper 75 to 150 feet 

of the shale. It is not confined to any definite horizon but may be 

expected anywhere within this portion. It is a compact, brittle, finegrained, nonmagnesian, even-bedded stone, is blue on weathered surfaces though black on fresh surfaces, and is closely set with veins 

of quartz and calcite half an inch or less thick. Some thin layers 

at or near the base contain sand and pebbles. The sand grains are 

well rounded and translucent; the pebbles are subangular, range 

from the size of peas to 2 inches in diameter, and consist of shale, 

fine-grained brown sandstone, and limestone like that of the adjacent beds. In some localities the limestone, like the beds both below
STBATIGKAPHY 33

and above, is greatly crumpled. Locally thin layers of black shale 

are interbedded with the limestone layers.

The limestone lenses, which have a maximum total observed thickness of about 85 feet, are made up of layers from a few inches to 2 

feet thick, and they thin down to a few feet or entirely disappear 

within short distances. (See pi. 6, B.) This abrupt thickening and 

thinning of the limestone, its sporadic occurrence, and the conglomerate that it contains led formerly to the conclusion that there is 

an unconformity at the base of the limestone. This view seemed 

to be confirmed by the paleontologic evidence in hand at the time, 

and the limestone and overlying beds up to the Bigfork chert were 

called the Stringtown shale.14 Subsequently graptolites from beds 

beneath the limestone were determined to be of the same age as those 

above, and this later evidence suggests that if any unconformity 

exists it is intraformational.

Fossils and correlation. Graptolites belonging to two faunas are 

known. One of these faunas is represented in the Beekmantown 

of New York and in contemporaneous beds of the Levis shale in 

Quebec, and the other, the younger, in the Normanskill shale in New 

York. The younger fauna is commonly known as the Nemagraptm 

gracilis or Normanskill shale fauna.

The older fauna is represented in the Hot Springs district by a 

single collection obtained near the base of the Womble shale in the 

NW. 1/4 sec. 39, T. 1 S., R. 20 W., and is said by Ulrich to be a Mazarn 

shale fauna, but the field relations apparently indicate that the shale 

yielding the fossils overlies the Blakely sandstone. The species were 

determined by Ulrich as follows:

Azygograptus sp. 

Didymograptus sparsus. 

Didymograptus cf. D. extensus. 

Brygraptus. 

Climacograptus. 

Diplograptus (large). 

Glossograptus horridus. 

Phyllograptus sp. 

Cryptograptus.

Several parts of the Womble shale in the Caddo Gap quadrangle 

have yielded graptolites belonging to the Normanskill shale fauna. 

Some of those collected in this area have been identified by Ulrich 

as follows:

Climacograptus bicornis Hall. 

Dicranograptus parvangulus. 

Dicellograptus sextans (Hall).

" Purdue, A. H., op. clt.
34 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Dicellograptus cf. D. sextans (Hall). 

Dicellograptus cf. D. smith! Ruedemann. 

Dicellograptus divaricatus (Hall). 

Didymograptus superstes (Lapworth). 

Didymograptus sagitticaulis Qurley. 

Nemagraptus gracilis Hall.

The largest collection containing this fauna was obtained by Ulrich 

at Crystal Springs, Ark., east of the Caddo Gap quadrangle, where 

the entire formation is better exposed than at any other known 

locality. The species as identified by Ulrich follow:

Didymograptus sagitticaulis Gurley.

Didymograptus superstes Lapworth.

Didymograptus? n. sp.

Nemagraptus gracilis Hall.

Dicellograptus gurleyi Lapworth.

Dicellograptus rigidus Lapworth.

Dicellograptus sextans Hall.

Dicellograptus cf. D. intortus Lapworth.

Dicellograptus cf. D. divaricatus bicurvatus Ruedemann.

Dicranograptus rectus Hopkinson.

Dicranograptus parvangulus Gurley.

Dicranograptus diapason Gurley.

Climacograptus bicornis Hall.

Climacograptus pultifer Lapworth.

Climacograptus n. sp. (very small).

Diplograptus (vulgatus) acutus Lapworth.

Diplograptus incisus (Lapworth) Ruedemann.

Diplograptus incisus n. var.

Diplograptus basilicus Lapworth.

Glyptograptus englyphus Lapworth.

Glyptograptus angustifolius Hall.

Glyptograptus angustifolius var.

Glossograptus ciliatus var.

Glossograptus n. sp. (wide).

Glossograptus n. sp. (same at Summit, Nev.?).

Orthograptus whitfieldi? Hall.

Cryptograptus tricornis Carruthers.

Retiograptus geinitzianus Hall.

Lasiograptus mucronatus Hall.

Lasiograptus bimucronatus Nicholson.

Lasiograptus bimucronatus n. var.

Thamnograptus capillaris Hall.

Dictyonema n. sp.

Desmograptus (? obovatus).

Callograptus cf. C. salteri Hall.

Ulrich states that out of 33 species found in one exposure at 

Crystal Springs 23 are listed from the Normanskill shale of New 

York by Ruedemann and 15 from the Glenkiln shale of England 

by Wood, Elles, and Lapworth. This fauna is also represented in
STBATIGEAPHY 35

the Martinsburg shale in Virginia, the Athens shale of Tennessee, 

Virginia, and Alabama, and the Stringtown shale of Oklahoma. 

The Normanskill shale, according to Ulrich, is .of upper Chazy age.

A fragment of a bryozoan belonging to the genus Rhinidicfya 

was found in limestone in the Womble shale at Crystal Springs. 

Although the age indicated by it is indecisive, Ulrich states that it 

is not younger than Black River and might be lower to middle 

Chazy.

A younger fauna than that of the Normanskill shale has been 

obtained from a hard black shale that lies just beneath the lowest 

chert beds of the Bigfork chert and that is provisionally included 

in the Womble shale, with which this black shale has been mapped. 

This fauna is represented by two collections. One of the collections 

was made by L. S. Griswold and C. S. Prosser at the Texas tunnel

mine, which is half a mile west of Crystal Springs, Ark.; it has 

furnished the following species which have been identified by Ulrich:

Dicranograptus arkansasensis Gurley.

Dicranograptus spinifer Elles and Wood.

Dicranograptus nicholsoni Hopkinson.

Climacograptus caudatus Lapworth.

Diplograptus calcaratus?

Diplograptus truncatus abbreviates Elles and Wood.

Mesograptus sp. undet.

Retiograptus (Orthograptus) quadrimucronatus var. cornutus Ruedemann.

Cryptograptus insectiformis Ruedemann.

Lasiograptus bimucronatus n. var. near L. timidius Ruedemann.

The other collection containing the younger fauna was obtained by 

L. S. Griswold and J. P. Smith from a locality in the SW. % SE. % 

sec. 23, T. 3 S., R. 28 W., in the northwestern part of the Caddo Gap 

quadrangle. The species that have been identified by Ulrich are as 

follows:

Dicranograptus arkansasensis Gurley. 

Dicranograptus spinifer Elles and Wood. 

Diplograptus cf. D. acutus Elles and Wood. 

Climacograptus cf. C. oligotheca Gurley. 

Retiograptus? n. sp.

The local guide fossil of this younger fauna is stated by Ul-rich to 

be Dicranograptus arkansasensis Gurley. The fauna according to 

him is the same as the faunas of the lower Hartfell shale of Scotland, 

of the Magog shale of Canada, and of the Snake Hill beds of the New 

York State survey. It is said by him to be of Trenton age and to be 

more closely allied to the fauna in the Bigfork chert than to the 

fauna in the Womble shale. . A collection of graptolites and other fossils which was obtained 

from black shale near the top of the Womble shale at a locality on a
36 DE QUEEN AND CADDO GAP QUADKANGLES. AKKANSAS

north hill slope one-eighth mile west of Buttermilk Springs has 

furnished the following species, which were identified by Ulrich:

Graptolites:

1. Leptograptus flaccidus spinifer Elles and Wood.

2. Dicellograptus patulosus Lapworth.

3. Azygograptus sp. undet.

4. Climacograptus bicornis Hall.

5. Climacograptus bicornis var.

6. Dicranograptus nicholsoni Hopkinson.

7. Dicranograptus spinifer (Lapworth) Elles and Wood.

8. Mesograptus near M. coelatus No. 1.

9. Mesograptus near M. coelatus No. 2.

10. Retiograptus (Orthograptus) cf. quadrimucronatus.

11. ?Diplograptus cf. D. acutus (Elles and Wood).

12. Cryptograptus cf. C. tricornis (Carruthers).

13. Retiolites? n. sp.?

14. Lasiograptus bimucronatus (Nicholson). 

Various types of sponge spicules. 

Leptobolus walcotti? Ruedemann. 

Schizotreta minutula Winchell and Schuchert (cf. species in Maquoketa).

Concerning the above collection Ulrich says: " Most of the species 

are the same as or clearly allied to species characterizing the upper 

part of the Nemagraptus gracilis zone. Nos. 8, 9,10, and 13 are more 

suggestive of the Bigfork chert and Polk Creek shale faunas. The 

graptolites indicate a horizon beneath the bed at the Texas tunnel 

mine."

BIGFORK CHERT

Definition. The Bigfork chert received its name from the fact 

that it is typically developed over a large area around Big Fork 

post office, in the northwest corner of the Caddo Gap quadrangle.

The formation is composed of chert interbedded with a small amount 

of shale and limestone and, as will be shown later, is known by its 

fossils to be of Middle Ordovician age. Its thickness can not be 

accurately measured owing to the intense crumpling of the beds, but 

it is estimated to be approximately 700 feet. In southeastern Oklahoma it is the basal part of the Talihina chert as defined by Taff.15 

The Bigfork in parts of the quadrangles under discussion was 

mapped by the Geological Survey of Arkansas as novaculite,18 but it 

differs materially from the true novaculite of the quadrangles in 

being of coarser texture and darker color, in being older, thinner 

bedded, and nontranslucent and in having a much more complex 

structure.

16 Taff, J. A., TJ. S. Geol. Survey Geol. Atlas, Atoka folio (No. 79), 1902. 

16 Griswold, L. S., Whetstones and the Novaculites of Arkansas: Arkansas Geol. Survey 

Ann. Kept, for 1890, vol. 3, 1892.
STRATIGRAPHY 37

The Bigfork chert is conformably underlain by the Womble shale 

and is conformably overlain by the Polk Creek shale, of Ordovician 

age, into which the Bigfork gradually passes by a thickening of its 

shale beds and a corresponding decrease in the number of its chert 

layers.

Distribution and character. The Bigfork chert extends westward 

across the northern part of the Caddo Gap quadrangle, being exposed in narrow belts along the north base of the Missouri and 

Caddo Mountains and in the valleys of Long and Blaylock Creeks, 

farther south. These belts extend westward a. short distance into 

the northeast corner of the De Queen quadrangle. They are all 

parallel with the adjacent high ridges, and their characteristic surface features are canyonlike valleys and low, steep-sided knobs, 

which are in reality foothills.

The formation, as previously defined, consists of chert interbedded 

with some shale and limestone. The chert is commonly in evenbedded layers having a thickness of 3 to 6 inches but at a few places 

thickening to 3 feet. It is very close textured and brittle and under 

the blows of a hammer flies into small pieces, most of which have an 

uneven but some a conchoidal fracture. Parts of it are finely 

laminated. It is black and dense when unweathered, but when 

weathered it ranges in color from slate to dark gray, the slate color 

occurring at most places. Some of the chert is rather porous and 

has the appearance of gray, soft, fine-grained sandstone. In some 

parts small quantities of calcite and pyrite are disseminated. Numerous joints, many of which are straight and have remarkably 

smooth glossy surfaces, form a network which cuts the layers in all 

directions. So numerous are the joints that it is difficult to obtain 

a hand specimen with fresh surfaces. In most parts the fractures 

along the joints are occupied by fine quartz veins containing a little 

calcite. The layers as a rule are greatly crumpled, and it probably 

was the strain accompanying the crumpling that formed the network 

of joints.

The shale is black, siliceous, and carbonaceous and forms evenbedded layers ranging from a fraction of an inch to several feet in 

thickness which are distributed throughout the formation, but it is 

meager or absent in places, particularly near the base. Black siliceous 

limestone in lenses and layers only a few inches thick occurs 

sporadically near the base and top.

Because of its minute jointing the formation rapidly breaks down

under the action of weathering agents, and large quantities of finely

broken material collect at the base of the knobs; but good rock

exposures are numerous on the steeper slopes and in the stream beds.

6242 29 4
38 IJ u QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Fossils and age. Fossils are rare in the Bigfork chert and consist 

chiefly of graptolites, though other invertebrate remains, which are 

practically indeterminable, have been found at a few localities in the 

Ouachita Mountains. Sponge spicules occur in the chert in southeastern Oklahoma, but if such remains are present in Arkansas they 

have not been observed. The collections of graptolites have been 

obtained from the upper part of the Bigfork chert in the Caddo Gap 

quadrangle. Their localities together with their specific identifications by Ulrich follow:

SB. 1,4 sec. 28, T. 3 S., B. 27 W.:

Dicellograptus cf. D. anceps (n. sp. or var.).

Retiograptus? (Orthograptus) quadrimucronatus.

Mesograptus (small form).

?Climacograptus antiquus var. 

SB. % sec. 6, T. 4 S., R. 26 W.:

Retiograptus? (Orthograptus) quadrimucronatus.

Climacograptus antiquus (var. or young). 

Northeast corner of SW. % sec. 27, T. 4 S., R. 27 W.:

Mesograptus (usual small form).

Climacograptus antiquus.

Retiograptus? (Orthograptus) quadrimucronatus.

Thus far the most extensive graptolite collection from the Bigfork 

chert in the Ouachita Mountain region has been obtained from the 

top 60 feet of the formation on Cedar Creek 6 miles northwest of 

Buckville, Montgomery County, Ark., about 12 miles north-northeast of the northeast corner of the Caddo Gap quadrangle. The 

species from this locality have been identified as follows by Ulrich:

Climacograptus sp. undet. 

Dicellograptus divaricatus Hall. 

Dicellograptus cf. D. divaricatus Hall.

Diplograptus trifidus (Gurley). 

Diplograptus vulgatus. 

Glyptograptus sp. 

Lasiograptus sp. 

Leptograptus flaccidus (Hall). 

Leptograptus sp. 

Mesograptus sp. undet. 

Mesograptus perexcavatus. 

Orthograptus sp.

Ulrich states that so far as these graptolites can be made out they 

suggest species found in the lower Hartfell shale of Scotland rather 

than any known in standard American sections. The well marked 

graptolite Orthograptus quadrimucronatus is found in both the lower 

and upper parts of the Bigfork chert. In Great Britain it is confined 

to the upper (Pleurograptus lineans) graptolite zone of the lower 

Hartfell, and in Canada to shale that has been generally referred 

to the Utica, As stated by Ulrich the age of the Bigfork " accord-
STRATIGRAPHY 39

ing to the American standard may thus be anywhere between lower 

Trenton and Utica,"

Other fossils, consisting of fragmentary shells, have been found in 

a chert layer and in associated limestone about 50 feet below the top 

of the formation on Blaylock Creek in the De Queen quadrangle. 

Concerning them Ulrich says:

Unfortunately these fragmentary remains are nearly ruined for purposes of 

identification by absorption and subsequent resilicification of the cavities. Possibly they represent a dozen species, but aside from a small flwdio. it is difficult to be certain even of their respective genera. For the present it will suffice 

to say that the collection indicates definitely that the Bigfork chert is of 

Mohawkian [Middle Ordovician] age.

The fossil evidence, therefore, apparently indicates that the Bigfork chert is of Trenton age.

FOLK CREEK SHALE

Definition. The Polk Creek shale received its name from Polk 

Creek, in the Caddo Gap quadrangle, along the headwaters of which 

it is typically developed. It is a black shale of Upper (?) Ordovician age, containing a few thin, widely separated layers of chert 

and sandstone. Its thickness ranges from a feather edge to 175 

feet, but the most common thickness is 100 feet. In southeastern 

Oklahoma this shale forms a minor portion of the Talihina chert.

The formation is underlain by the Bigfork chert, into which it 

passes by a somewhat gradual lithologic change. In the Cossatot 

Mountains and in a few places in the Caddo Mountains it is succeeded by the Blaylock sandstone of Silurian age; and in the Caddo 

and Missouri Mountains, where the Blaylock is usually absent, it is 

succeeded by the Missouri Mountain slate, also Silurian.

A stratigraphic break may exist between the Blaylock and the 

Polk Creek, but the only evidence for it is a conglomerate that has 

been found at the base of the Blaylock in the De Queen quadrangle. 

Such a break may occur also between the Polk Creek and Missouri 

Mountain formations in the areas where they are in contact; but 

the only evidence for this is the fact that the intervening Blaylock 

thins out to the north. An unconformity between the Polk Creek 

and Missouri Mountain formations in the Hot Springs district seems 

obvious from the character of a conglomerate that occurs at the base 

of the Missouri Mountain slate there.

Distribution and character. The Polk Creek shale is exposed in 

the Caddo and Cossatot Mountains in both the Caddo Gap and 

De Queen quadrangles. In the Caddo Gap quadrangle it is present 

throughout the mountain belts, except in the vicinity of Prior and
40 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Blaylock Mountains. The exposures are narrow strips which occur 

both on the mountain slopes and in the valleys and which are parallel 

with the trend of the mountain ridges. Their small width is due to 

the folded attitude and thinness of the formation. Although the 

shale is concealed by residual material from the shale itself and by 

debris from the adjacent strata that are exposed higher on the mountain slopes, rock outcrops are numerous, especially along ravines and 

stream beds.

The shale is black, fissile, and carbonaceous. In parts it is clayey, 

soft, and carbonaceous enough to soil the fingers in handling, but 

in others, especially in the lower part, it is a hard siliceous slate, 

sonorous when struck, and splitting with a cleavage that in places 

is at an angle with the bedding. On weathering it changes to a soft, 

gray, platy stone or disintegrates to clay. Thin layers of black dense 

chert like that of the Bigfork chert and thin layers of hard quartzitic sandstone are common in the formation, but they constitute a 

very small part of it. A lens of black oolitic limestone, which 

reaches 2 feet in thickness and contains many thin veins of calcite, 

occurs in the shale on Sugar Creek in the De Queen quadrangle.

This formation, like those below and above, has been intensely 

crumpled, so that in places it appears thicker than it actually is, and 

as a result of this crumpling it contains many slickensides and joints. 

Thin veins of white quartz are found along the joints and bedding 

planes, and small crystals of pyrite can be found disseminated 

through the shale in nearly all fresh exposures.

Fossils and edge. Fossils, nearly all of which are graptolites, are 

rather plentiful in the Polk Creek shale, especially in the basal part, 

and can be found in most good exposures. The following list of 

species, identified by Ulrich, contains most of those collected in the

Caddo Gap and De Queen quadrangles:

Leptograptus ? (?Dicellograptus) flaccidus trentonensis. 

Dicellograptus morrisi? 

Dicellog'raptus cf. D. complanatus Lapworth. 

Dicellograptus complanatus, three new varieties. 

Diplograptus (group of D. calcaratus) cf. D. incisus. 

Diplograptus cf. D. acutus and Mesograptus foliaceusl 

Mesograptus (?Amplexograptus), one or two species. 

Mesograptus (?Amplexograptus) sp. No. 3. 

Retiograptus? (Orthograptus) n. sp. 

Retiolites? n. sp.

The largest graptolite collection from the Polk Creek shale in the 

Ouachita Mountains came from a locality on Cedar Creek 6 miles 

northwest of Buckville, Montgomery County, Ark., about 12 miles 

north-northeast of the Caddo Gap quadrangle the same locality that
STRATIGRAPHY 41

yielded the large collection from the Bigfork chert (p. 38). The 

species as identified by Ulrich are as follows:

Amplexograptus sp. unclet.

Climacograptus sp.

Diplograptus n. sp.

Glossograptus sp.

Dicellograptus aft'. D. complauatus Lapworth.

Dicellograptus coinplanatus ornatus (Elles and Wood).

Dicellograptus cf. D. complanatus ornatus.

Dicellograptus cf. D. auceps Nicholson.

Dicellograptus forchammeri Geinitz.

Dicellograptus aff. D. forchammeri.

Dicellograptus forchammeri var. or n. sp.

Dicellograptus forchammeri var. flexuosus.

Dicellograptus elegans (Garruthers).

Dicellograptus n. sp.

Orthograptus quadrimucronatus Ami.

Orthograptus spinigerus.

Orthograptus cf. O. intermedius.

Lasiograptus.

Mesograptus $$>. undet.

Nymphograptus velatus (Elles and Wood).

Retiograptus? or n. gen.

The Polk Creek shale graptolites are stated by Ulrich to be comparable with species occurring in Great Britain in the Hartfell shales, 

chiefly in the upper Hartfell, rather than with any species described 

from America. The correlation of the Polk Creek shale is further 

discussed in the following statements by Ulrich: 17

In Scotland the Hartfell shales are placed at the top of the Ordoviciau. 

Lapworth divides this body of shale into two groups and recognizes three rich 

graptolite zones in the lower and two, separated by an unfossiliferous mudstone, in the upper. The lower group contains some species that have been 

identified also in America. Here most of them are confined to various horizons 

supposed to be of the age of the Trenton group. Others have been seen in this 

country as yet only in the older Normanskill shale, while the remaining two or 

three species are from shales now referred to the Utica. The lower Hartfell 

zones may thus be somewhat loosely correlated with our Trenton.

The graptolites of the upper Hartfell zones suggest two faunas in America 

In the Polk Creek shale we find Dicellograptus complanatus, which is characteristic of the lower of the two upper Hartfell zones. In America, however, 

this graptolite ranges with very slight modification through the whole of the 

Polk Creek shale. Apparently the same species is found also in the Sylvan 

shale of Oklahoma. Though the Sylvan shale seems to be much younger than 

the Polk Creek shale, a comparison of their respective faunas shows that 

besides Dicellograptus complanatits, also Diplograptus crassitestus and Climacograptus ulrichi are represented in both by indistinguishable species or close 

varieties.

17 Dlrich, E. 0.. The Ordovician-Silurian Boundary: Cong. g6ol. internat., 12° sess., 

Compt. rend., pp. G20-621, 1914.
42 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Perhaps the most important of the facts brought out by comparison of the 

British upper Hartfell graptolites with American species is the presence of 

Dicellograptus complanatus var. ornatus in the upper part of the Polk Creek 

shale in Arkansas, This well-marked variety is found in Scotland only in the 

upper part of the upper Hartfell that is, in the Dicellograptus anceps zone. 

If this variety actually holds the same stratigraphic position in the two countries, and if Dicellograptus complanatus appeared about the same time in both 

places, then we might say that the essential equivalence of the Polk Creek 

shale and the upper Hartfell shale is assured. At the same time the upper 

limit of the Ordovician would be determined, in at least one American section, 

the same as it is in Britain.

Though the associated graptolites are perhaps less diagnostic than these 

dicellograptids, their evidence seems confirmatory. Compared with British 

species, the six or eight Diplograptidae of the Polk Creek shale, though perhaps 

in no case exactly identifiable with forms described by Biles and Wood, would 

yet seem not out of place in either a lower or an upper Hartfell zone. Some of 

them even suggest species from the younger Birkhill shale. Besides the 

Diplograptidae and the previously-mentioned dicellograptids the Polk Creek 

shale contains also a Leptograptus allied to the long-ranging L. flaccidus, a 

third Dicellograptus, reminding in this case of D. morrisi, and a RetioUtes. 

The last three have been found only in the lower third of the formation.

Judging solely from internal faunal evidence, it would igeem, therefore, that 

the base of the Polk Creek shale can not be older than lower Hartfell. That 

it is indeed younger and probably altogether upper Hartfell is indicated by the 

fact that the range of Orthograptus quadrimu'cronatus generally underlies the 

Polk Creek shale. In the Ouachita region this well-marked graptolite is found 

in the lower and upper parts of the Bigfork chert. In Britain 0. quadrvmucronatus is confined to the upper (Pleurograptus linearis) graptolite zone of the 

lower Hartfell and in Canada to shales that have been quite generally referred 

to the Utica.

Locally in Arkansas the upper 50 feet or more of the 0. quadrimucronatus 

zone consists entirely of siliceous shale or slate. In such instances the lower 

boundary of the Polk Creek has been mapped so as to include a part of this 

zone. It seems well to add here that certain graptolite collections credited to 

the lower part of the Polk Creek shale remind of lower Hartfell rather than 

upper Hartfell zones. In fact the various local collections from shales 10 to 

50 feet above the top of the Bigfork chert are often so different that it does 

not seem possible that they all represent the same zone. It may well turn 

out, therefore, that older graptolite zones than those of the upper Hartfell are 

locally represented in the siliceous black shales that it was found convenient 

to include in the Polk Creek shale rather than in the underlying Bigfork 

chert.

SILURIAN SYSTEM

BLAYLOCK SANDSTONE

Definition. The Blaylock sandstone received its name from Blaylock Mountain, on Little Missouri River, in the Caddo Gap quadrangle, at the east end of which it is well exposed. It consists of 

sandstone and some shale, which are known by their fossils to be 

of Silurian age. The Talihina chert in southeastern Oklahoma, as 

defined by Taff,18 does not include the Blaylock sandstone, for the

18 Taff, J. A., U. S. Geol. Survey Geol. Atlas, Atoka folio (No. 79), 1902.
STRATIGRAPHY 43

Blaylock is absent in that State except in McCurtain County, but the 

Talihina includes rocks that are both older and younger than the 

Blaylock. (See correlation chart opposite p. 22.)

Distribution mid thickness. The Blaylock has a smaller areal 

extent than most other formations of the Ouachita region. Although 

it occurs through the whole length of the region in Arkansas and in 

McCurtain County, Okla., it is limited to a narrow belt in the southern 

part of the region. In the quadrangles herein described its principal 

outcrops are in the Cross and Cossatot Mountains, though a few 

blocks of talus from beds probably not more than 10 feet thick 

are found on the Missouri Mountains in the De Queen quadrangle 

and on the north slope of the Caddo Mountains as far west as Statehouse Mountain in the Caddo Gap quadrangle. Its outcrops are

rough, rocky strips with a nearly east-west trend and OCCUP OH mountain slopes and in narrow valleys. Rock ledges are common, but 

at most places the sandstone is concealed by debris. The thickness 

of the formation ranges from a feather edge to an estimated maximum of 1,500 feet; an accurate determination is impossible because 

of the close crumpling of the strata, which produces a repetition of 

beds in probably all places where any great thickness is exposed.

Character. The formation consists of sandstone and shale, which 

differ in proportion both vertically and horizontally, though the 

sandstone usually occurs in greater amount. The sandstone is in 

remarkably even bedded layers from 1 to 6 inches thick, but in a few 

places the layers reach a thickness of 3 feet. It consists of fine angular 

quartz grains and a little mica with quartz as the cementing material, 

and in addition to these minerals microscopic examination of a thin 

section of a specimen from Bog Springs, in the De Queen quadrangle, 

reveals small quantities of plagioclase, orthoclase, zircon, tourmaline, 

pyrite, chlorite, and limonite. Most of the sandstone is hard, dense, 

light to dark gray, laminated, and quartzitic. but some is soft and 

has a yellow color and splits into more or less parallel plates when 

struck with a hammer. Flattened clay pellets and rather fine, crooked 

markings that are probably worm trails are common. Joints are 

numerous, and many of them are filled with thin veins of white 

quartz. On weathering the sandstone breaks up into angular fragments that lie scattered over the surface, and in places it turns brown 

but elsewhere it retains its gray color. The shale is interbedded with 

the sandstone and makes up a considerable part of the formation 

fully 90 per cent of it in some localities in the northeast corner of the 

De Queen quadrangle but in parts through 100 feet or more it is 

almost entirely absent, the sandstone layers coming together. It is 

micaceous, dark colored, argillaceous, and in many places black and 

fissile, but in others it is buff, thus closely resembling the Missouri
44 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Mountain slate. In the places in the northeast corner of the De Queen 

quadrangle where shale constitutes the greater part of the formation 

most of the shale is buff, and in those areas as well as in some adjoining parts of the Caddo Gap quadrangle the contact between the Blaylock and Missouri Mountain formations is difficult to determine and 

can be mapped only arbitrarily.

A conglomerate, ranging from 2 to 4 feet in thickness and consisting of rounded chert pebbles in a dark-colored, siliceous, fine-grained 

matrix, was found at the base of the Blaylock on Sugar Creek, southeast of Shady post office, in the De Queen quadrangle. Some cavities 

that occur in this conglomerate were obviously once occupied by 

pebbles, probably of limestone, which have been removed by solution.

The Blaylock sandstone closely resembles much of the Stanley 

shale described below. Because of this resemblance, combined with 

the complexity of the structure over most of the quadranges, the 

authors have been temporarily at a loss to distinguish these formations in places.

Stratigraphic relations. The Blaylock sandstone is apparently 

conformable with the underlying Polk Creek shale so far as concordance in the bedding of the two is concerned, but the conglomerate at 

the base of the Blaylock in the De Queen quadrangle, although it is 

of only local distribution, suggests a stratigraphic break at this 

horizon. The Blaylock is overlain by the Missouri Mountain slate, 

believed to be of Silurian age. Unfortunately contact exposures are 

so few as to make it difficult to determine definitely the relations of 

the top of the sandstone. Some features of the formation shown in 

this and other parts of the Ouachita region suggest an unconformity

at its top. One of these' features is the local occurrence of a conglomerate at the base of the Missouri Mountain slate, and another is 

the abrupt appearance of the Blaylock and rapid thickening from 

the north toward the south. Within a distance of 3 miles in the 

Caddo Gap quadrangle the formation increases in thickness from a 

feather edge to 1,500 feet. This difference may be due to an erosion 

interval during which the formation was removed from what was 

then the highest part of the region. The other feature that suggests 

an unconformity is the much crumpled condition of the Blaylock 

sandstone and underlying formations compared with those overlying 

it. On the other hand, little direct evidence of a stratigraphic break 

has been observed, and in the Caddo Gap quadrangle as well as in the 

De Queen the shale of the Blaylock sandstone appears to pass without lithologic change into the Missouri Mountain slate.

The alternative suggestion to account for the rapid thickening is 

that the formation was put down in a rapidly subsiding trough, whose
STRATIGEAPHY 45

northern border extended in an east-west direction across part of the 

Ouachita region. The suggestion to account for the intense folding 

is that the sandstone, because it is thin bedded, was not so competent 

as the overlying massive Arkansas novaculite and was crumpled by 

the horizontal compression movements, though beneath the great 

weight of overlying rocks, whereas the novaculite adjusted itself to 

the crustal shortening by shearing and thrust faulting. The novaculite also protected the immediately underlying Missouri Mountain 

slate from excessive crumpling.

Fossils and correlation. The Blaylock sandstone is very sparingly 

fossiliferous. A few remains of Diplograptidae have been noted in 

sandstone layers at three or four localities in the Ouachita Mountain 

region, but these are too poorly preserved to be identified specifically. 

The interbedded shale on Little Missouri Kiver at the south base of 

Blaylock Mountain, in the Caddo Gap quadrangle, has yielded a small 

collection of graptolites, which have been determined as follows by 

E. 0. Ulrich:

Monograptus distans (Portlock). 

Monograptus gregarius (Lapworth). 

Monograptus argutus (Lapworth). 

Monograptus aff. M. fimbriatus l Nicholson). 

Dimorphograptus decussatus (Elles and Wood). 

Gladiograptus perlatus (Nicholson). 

Dictyonema sp. undet.

These species, as pointed out by Ulrich, are not comparable to any 

described forms from America but have all been described from specimens obtained in the Birkhill shales of Scotland, which are in Great 

Britain considered the base of the Silurian system. The Blaylock is 

therefore assigned by Ulrich to the early Silurian.

MISSOURI MOUNTAIN SLATE

Definition. The Missouri Mountain slate was named from the 

Missouri Mountains in the De Queen and Caddo Gap quadrangles, 

in which it is well developed. The formation has been changed by 

regional metamorphism from shale to slate at most places in the 

quadrangles, but it is still shale at others. The Talihina chert in 

southeastern Oklahoma, as defined by Taff,19 includes this slate. 

(See correlation chart opposite p. 22.) The Missouri Mountain 

slate is apparently of Silurian age, but this age assignment is based 

solely upon its lithologic character and stratigraphic relations, for 

no fossils have yet been found in it.

Distribution amd thickness. The slate is exposed in the Cross, 

Caddo, and Cossatot Mountains, in both of the quadrangles here

10 Taff, J. A., U. S. Geol. Survey Geol. Atlas, Atoka folio (No. 79), 1902.
46 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

described. The outcrops are narrow belts which occur in some places 

on one side of the ridges, in others on both sides, and in still others 

near the crests, their position depending upon the structure whether 

it is monoclinal, synclinal, or anticlinal. These three types of outcrop will be understood by reference to the structure sections of 

Plate 15. The surface in these belts is largely covered by residual 

material from the slate itself and by debris from other formations 

higher on the ridges, so that actual exposures are not common except on the steeper slopes and in or near stream beds. In places on 

the slopes of Missouri and Statehouse Mountains some of the exposures form low bluffs, most of which are even-faced, owing to the 

breaking off of the slate along joint planes.

The thickness ranges from 50 feet or less to 300 feet; the thinnest 

part occurs along the most southern outcrops, and the thickest in the 

Missouri Mountains.

Character. The formation consists of shale in parts of the quadrangles, but the bulk of it is a soft clay slate that is hard enough in 

places to emit a clear ring when struck with a hammer. A conglomerate at the base and a few thin layers of sandstone and quartzite are 

present here and there. A few feet of slate at the base is green at 

some places, is locally somewhat sandy, and contains small crystals of 

iron pyrites. The slate above the basal portion ranges from bloodred to dark brownish red, but has patches and streaks of green. The 

green patches may be seen in stream beds and in quarries and othel 

exposures, and the streaks, which are as much as 2 inches wide, may 

be seen along joints. Green may have been the original color of the 

slate at the base, but the color of the green patches and streaks higher 

in the formation is secondary, the original color being red. Some 

parts of the slate have weathered to a buff color. The red color is 

due to the presence of the red iron oxide hematite; the green color 

is due to chlorite.

The,red and green slates are remarkably homogeneous, are in most 

parts dissected by joints in two or more sets running in different 

directions, and have well-developed slaty cleavage, which in places 

is parallel with and elsewhere is oblique to the bedding, permitting 

it to be split into thin pieces, most of which have even and glossy 

surfaces. The joints may be seen in all exposures. Their closeness 

depends upon the amount of close folding that the slate has undergone at any particular place. Where the folding has been least intense the joints are a few inches to 10 or 12 feet apart, but where it 

has been most intense they are a quarter of an inch or less apart, 

and here the slate on weathering breaks up into small prisms resembling shoe pegs.

The top 10 feet of the slate on Statehouse Mountain and the upper 

50 or 60 feet on Sugartree Mountain, in the Caddo Gap quadrangle,
STRATIGRAPHY 47

and probably some in other parts of the quadrangles is black, but in 

the Hot Springs district this color is common throughout the formation. The exposed ledges and surface fragments of the slate are 

generally buff, black, green, yellow, or reddish brown. In weathered 

outcrops in the Hot Springs district the black shale is shown to pass 

gradually through green to buff and yellow; the last three colors are 

secondary.

The sandstone and quartzite are in layers from 3 to 5 inches 

thick and occur in places near the base and top of .the formation. 

They are gray and hard and are composed of rounded, translucent 

quartz grains. On Missouri Mountain, in the De Queen quadrangle, 

a layer of conglomerate 15 inches thick and also thinner ones, all 

made up of chert pebbles in a siliceous matrix resembling novaculite* 

occur in the upper part of the slate. ° A conglomerate 1 ,to 4 inches

thick, consisting of rounded chert pebbles in a shale matrix, was 

observed at the base of the slate in the water gap west of Hightop 

Mountain, in the Caddo Gap quadrangle. Fragments of conglomerate near the base were found in other parts of the quadrangles, but 

none were seen in place. Farther east, in much of the Hot Springs 

district, there is a basal conglomerate of rather wide distribution. 

The following microscopic analyses of ,the red and green varieties 

of the Missouri Mountain slate were made by Dale: 20

Dark reddish slate, from Mena, near Big Fork: In color this slate is somewhat darker than the " red " slate of New York. To the unaided eye it has a 

minutely granular texture and a roughish, speckled, almost lusterless surface. 

Contains very little magnetite, does not effervesce with cold dilute hydrochloric 

acid, is sonorous, splits readily, and has some argillaceous odor. Under the 

microscope it shows a matrix of muscovite (sericite), with brilliant aggregate 

polarization, quartz grains ranging up to 0.025 millimeter, muscovite and 

chlorite scales, and abundant hematite in minute dots. There are also rhombs, 

from 0.1 to 0.2 millimeter, of chlorite and rhodochrosite, probably pseudornorphs. 

No other carbonate. The constituents, arranged in descending order of abundance, appear to be muscovite, hematite, kaolin, quartz, chlorite, rhodochrosite 

(?), and magnetite. This slate compares favorably in texture with the "red" 

slate of New York.

Light-greenish slate, from the Missouri Mountain slate, locality not designated : This * * * to the unaided eye has an exceedingly fine texture and 

a very fine, almost lusterless cleavage surface; shows pyrite on sawn edge; 

contains a little magnetite; does not effervesce with cold dilute hydrochloric 

acid, is sonorous, very fissile, and has a slight argillaceous odor. Under the 

microscope it shows a matrix of muscovite (sericite), with a brilliant aggregate 

polarization and great evenness of texture. A very minute bed of quartz grains, 

chlorite, and muscovite lies irf the cleavage, which is therefore the bedding also. 

The grain is indicated by the transverse position of some of the muscovite 

scales. Quartz not very abundant, but occurs in grains up to 0.037 millimeter. 

Rutile needles abound from 0.0028 by 0.0009 up to 0.014 by 0.0014 millimeter.

«> Dale, T. N., Slate in the United States: U. S. Geol. Survey Bull. 586, pp. 63-64, 1914.
48 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Muscovite and chlorite scales occur, the latter producing the green color. There 

are some opaque granules (limonite? and pyrite), occasional lenses, 0.14 millimeter long, of a central mass (probably rhodochrosite), with secondary muscovite at both ends. No other carbonate. Shows a number of tourmaline prisms 

up to 0.025 by 0.008 millimeter. The chief constituents, arranged in descending 

order of abundance, appear to be muscovite, quartz, kaolin, chlorite, rutile, 

pyrite, magnetite, and tourmaline. This mica slate probably possesses more 

petrographic interest than economic value. Its flssility, freedom from carbonate, 

and color are very favorable, but it will probably be found too delicate for use 

on a roof.

Stratigraphic relations and age. In the Cross and Cossatot Mountains and in a few localities farther north the Missouri Mountain 

slate succeeds ,the Blaylock sandstone of Silurian age. Northward 

in the quadrangles under discussion it overlaps that sandstone and 

rests upon the Polk Creek shale, of Ordovician age, at most localities 

in the Caddo Mountains. This overlap and a conglomerate found at 

the base strongly suggest a stratigraphic break at the base of the Missouri Mountain slate. The possible relations of the formation to the 

Blaylock sandstone are rather fully discussed in the description of 

the Blaylock.

The Missouri Mountain slate is apparently conformable w,i.th the 

succeeding Arkansas novaculite, into which it seems to grade lithologically, as indicated by the presence of thin shale beds like the Missourj 

Mountain slate in the lower part of the novaculite, but a conglomerate 

separates the two formations at Hot Springs, Ark., and in southeastern Oklahoma. This conglomerate is not known to have a general 

distribution in Arkansas, and its local occurrence there may not indicate an unconformity at the top of the slate.

No fossils have been found in the Missouri Mountain slate. Its 

correlation is therefore based upon its stratigraphic relations and 

lithologic character. The position of the slate between the Blaylock 

sandstone, of early S.ilurian age, and the Arkansas novaculite, the 

lower part of which is of Onondaga (Middle Devonian) age, indicates that this slate is Silurian or Devonian. The nearest exposures 

of Silurian and Devonian rocks outside the Ouachita-Mountains 

are ,in the Ozark region in northern Arkansas and northeastern 

Oklahoma, in the Arbuckle Mountains in southern Oklahoma, and 

on the southwest flank of the Nashville dome in Tennessee. The 

rocks of these systems are poorly represented in the Ozark region 

and the Arbuckle Mountains, and no part of them resembles in 

lithology the Missouri Mountain slate. /They are, however, well 

developed on the southwestern flank of the Nashville dome, where 

strata of Silurian age are succeeded by strata of Helderberg, Oriskany, Onondaga, and later age, ,in the order named. Although the 

Silurian rocks of Tennessee consist mainly of limestone, they contain 

considerable thicknesses of earthy and shaly limestone, which, in the
STEATIGEAPHY 49

basal part of the strata of Niagara age, changes in color from gray 

to red as the Mississippi embayment ,is approached. The rocks of 

Devonian age earlier than the Onondaga in Tennessee contain no 

beds w.ith a red color. It seems reasonable, therefore, to assume that 

the Missouri Mountain slate is equivalent to at least a part of the 

Sijurian rocks ,in Tennessee. If this supposition is true, the absence 

of calcareous deposits of this age in the Ouachita Mountains and 

their presence in the Arbuckle Mountains, the Ozark region, and 

the Nashville dome may be accounted for by the varying topographic 

features on the land area that supplied the clastic material and by 

variations in the character of the material and in the conditions of 

its deposition. The authors believe that the low-lying, deeply 

weathered land mass that supplied the red mud for the Missouri 

Mountain slate existed in northern Louisiana and eastern Texas,

where it is now concealed by Cretaceous and younger sediments.

If the reference of the Missouri Mountain slate to the Silurian system is correct, it follows that strata of Helderberg and Oriskany 

age are not present in the quadrangles under discussion. Their 

absence may be attributed to an unconformity at the top of the slate, 

for which there is some evidence, though not enough to be conclusive.

DEVONIAN SYSTEM 

ARKANSAS NOVACULITE

Definition. The Arkansas novaculite consists predominantly of 

novaculite with subordinate though considerable amounts of shale 

and conglomerate.

Novaculite as it is found in the Ouachita Mountains of Arkansas 

and Oklahoma is a gritty, fine-grained, homogeneous, highly siliceous 

rock, possessing a conchoidal or subconchoidal fracture and being 

translucent on thin edges. The name novaculite was first applied to 

the rock by Henry E. Schoolcraft in 1819. The authors regard it 

as belonging to the class of cherts.

The occurrences of novaculite are not as common as the occurrences of other sedimentary rocks, such as shale, sandstone, and 

ordinary chert, but it is widely distributed in the quadrangles herein 

described and in other" parts of the Ouachita Mountains. Although 

the novaculite is exposed throughout much of the length of these 

mountains, a distance of about 200 miles, it is thickest and best 

developed and has its largest areal extent in Arkansas. Hence the 

formation has been appropriately named the Arkansas novaculite. 

The novaculite corresponds to the upper part of the Talihina chert 

of southeastern Oklahoma.

Distribution and surface form. Within these quadrangles the 

Arkansas novaculite is exposed in the Cross, Caddo, and Cossatot
50 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Mountains. Here, as in other parts of the Ouachita Mountains, the 

outcrops are narrow, more or less parallel, nearly east-west belts, 

whose small width is due to the steep dip of the formation. Owing 

to the narrowness of the belts and to ,the greater resistance of the 

novaculite to weathering than that of the adjacent strata above and 

below, its outcrops stand up as sharp ridges, whereas the older and 

younger rocks form intervening valleys. Consequently the mountainous districts of the quadrangles present a corrugated surface 

when viewed from any of their highest elevations.

The crests of the ridges attain a common elevation, but rising 

above them are low peaks whose existence is due to local synclinal 

or anticlinal folds in the novaculite. Prominent among these peaks 

are Tall Peak, Kaspberry Peak, East Hanna Mountain, West Hanna 

Mountain, Eagle Mountain, High Point, and Whisky Peak, in the 

De Queen quadrangle; and Brushheap, Hogpen, Hightop, Tweedle, 

Wilson, and Strawn Mountains, in the Caddo gap quadrangle.

The brittleness, of the novaculite and its many joints cause it to 

break down into angular blocks and fragments which cover the ridges 

in most places, but in others, particularly along the crests and in the 

water gaps, the edges of the beds project through the debris as 

rough bare ledges, some of which are several feet high. (See pi. 

7, A.) On the west side of Board Camp Creek in the De Queen quadrangle, a single bare ledge of novaculite 3 to 6 feet thick juts out 

on a hill slope and rises vertically above the creek to a height of about 

75 feet. It is known as Standing Rock. (See pi. 2.) About onetenth of a mile north of this ledge, on the east side of the same stream, 

is a similar though lower projecting ledge known as Devil's Pulpit.

Thickness. The Arkansas novaculite is thickest in the Caddo, 

Missouri, and Cossatot Mountains, where, in many places, if not in 

most, it is about 900 feet thick. The greatest known thickness is 

950 feet and was measured 1 mile west of West Hanna Mountain. 

At Caddo Gap the formation is about 890 feet thick. It decreases 

in thickness both northward and westward. Along the northern 

border of the De Queen quadrangle it is in places only about 250 

feet thick, and on account of this northward thinning the ridges composed of it become lower in this direction. In the Cross Mountains 

the formation ranges in thickness from 300 to 550 feet.

Character. The formation, as developed in these quadrangles and 

in many other parts of the Ouachita Mountains, consists of three 

lithologic divisions a lower one, made up almost entirely of massive, 

white novaculite; a middle one, consisting mainly of thin layers of 

dense, dark-colored novaculite interbedded with shale; and an upper 

one, consisting chiefly of massive, highly calcareous novaculite. 

These divisions differ in thickness and character from place to place.
STRATIGRAPHY 51

The lowest part commonly ranges in thickness from 150 to 300 

feet, but reaches a maximum of 410 feet at Caddo Gap and a minimum of 10 feet in the extreme northeast corner of the De Queen 

quadrangle. This division is made up almost wholly of typical 

novaculite, whose color and massiveness make it the most conspicuous part of the formation. In fact, it is this part that occupies the 

crests of the ridges. The beds range from 2 to 10 feet in thickness 

and are generally uniform, though in places thin lenses wedge in between them. Some of the exposed bedding planes show large, uneven ripple marks. At a number of places beds of red and buff and 

less commonly black and green shale reaching 15 feet in thickness 

are interbedded with the basal layers of this division of the 

formation.

The massive novaculite is fine grained, homogenous, highly siliceous, translucent on thin edges, and white with a bluish tint, but 

where unweathered it is bluish gray. It possesses an uneven to 

conchoidal fracture and a waxy luster like that of chalcedony. 

Though the bulk of the novaculite is white, much of it is colored in 

various shades of red, gray, green, yellow, brown, and in many places 

black; the darker colors are prevalent in the lower 50 to 75 feet. 

These colors are produced by iron and manganese oxides and possibly in some places by carbonaceous matter. In parts, especially 

near the base, the novaculite has fine parallel laminations, and much 

of it contains a few cavities that are oval in cross section and half 

an inch in their longest dimension. The fresh unweathered novaculite contains a little calcite in particles of microscopic size uniformly 

disseminated through it, but exposures of the calcareous stone are 

few and have been found only in stream beds and in road cuttings 

through water gaps. Much of the white novaculite, as pointed out 

by Owen,21 is "equal in whiteness, closeness of texture, and subdued 

waxy luster, to the most compact forms and white varieties of Carrara marble; and, though of an entirely different composition, it 

resembles this in external physical appearance so closely that, looking at specimens of these two rocks together, it is difficult to 

distinguish them apart." Joints in several sets are numerous and run 

in all directions, but the most prominent are those normal to the 

bedding. Many of them are occupied by white quartz veins, which 

are usually so thin as to be inconspicuous. Slickensides along both 

joints and bedding planes are common.

The middle part of the formation ranges in thickness from a minimum of probably 75 feet in the vicinity of East Hanna Mountain 

to a maximum of 525 feet near West Hanna Mountain. It consists

21 Owen, D. D., Second Report of a Geological Reconnaissance of the Middle and Southern Counties of Arkansas, p. 23, Philadelphia, 1860.
52 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

chiefly of interbedded shale and novaculite. The novaculite is similar 

to that in the lower, massive part of the formation, except that the 

common color is dark gray to black and that the beds are much 

thinner, usually ranging from 1 to 6 inches in thickness. Moreover, 

some thin layers are argillaceous and possess a fairly good cleavage, 

resembling in these respects a highly siliceous shale. The whole 

division is cut by many joints, some of whose faces are so smooth 

that they look as if they had been polished. In some places the 

novaculite layers are partly and in others wholly replaced by beds 

of conglomerate from 1 inch to 2 feet thick. The matrix of this 

conglomerate is very compact novaculite; its pebbles are small and 

well rounded to subangular, and the larger percentage are composed 

of novaculite, though some are of sandstone or other hard rock. 

"Where these beds are present, fragments from them form conspicuous 

debris, attracting attention because of their smooth, spotted joint 

surfaces, which are at right angles to the bedding and are straight 

and even, irrespective of the hard pebbles.

The shale ordinarily observed is black, weathering to a buff or 

brown color, and it occurs in beds of uniform thickness, ranging from 

a fraction of an inch to TO feet. It is usually fissile argillaceous shale, 

but in places has been hardened to slate. Much of it is notably like 

the lower part of the Stanley shale. On Shields Creek, in the Caddo 

Gap quadrangle, 20 feet of the shale and in other places a smaller 

part of it is red. Although the red shale resembles the Missouri 

Mountain slate, it differs in having dull cleavage surfaces and in 

exhibiting on the cleavage surfaces faint elongated markings parallel 

with the bedding.

The upper part of the formation, though of considerable east-west 

extent in the Ouachita Mountains, is present, so far as known, only 

along their southern border, having been planed off oil the north 

during the post-Devonian erosion interval that followed the deposition of the materials forming the novaculite. It is believed to be 

present everywhere in the two quadrangles. Its thickness ranges 

from about 20 to 125 feet, and the thickest parts are along the most 

southern exposures of the formation. So resistant is this part of 

the formation that in some places where it and the underlying beds 

of the formation are not overturned it produces low ridges and 

knobs on the slopes of the higher ridges. The best example of such 

ridges and knobs is along the south side of the first ridge north of 

Dog Mountain, in the De Queen quadrangle. This part of the 

formation consists chiefly of massive, highly calcareous light-gray 

to bluish-black novaculite with some thin beds of ordinary dense 

chalcedonic novaculite like that characteristic of the middle and 

lower parts of the formation. Some of the calcite apparently con-
STRATIGKAPHY 53

,1! tains manganese and is hence a mangahiferous calcite. Honess 22 has 

found manganese carbonate to be abundant in the upper division qf 

the formation in McCurtain County, Okla. Fine lamination,parallel 

with the bedding is common. On" weathering, the more calcareous 

rock loses its calcium carbonate, becomes white or cream-colorecl!, 

porous, and soft enough to receive impressions from the hammer 

without breaking, and shows a great many oval and irregular-shaped 

cavities like those in the basal division of the formation. These 

cavities are due to the removal of calcium carbonate through solution. The shape of some of the cavities suggests that they may'be 

casts of poorly preserved shells. : ''

Near the Arkansas-Oklahoma line a few 'lenses of dark-gray, 

finely crystalline nonmagnesian limestone as much.as 15 inches.thick

are interbedded with the calcareous novaculite in the upper part of

the formation. The limestone, as well as the associated novaculite, 

contains well-rounded grains of translucent detrital quartz, which 

are visible with the aid of a pocket'lens. Although some dense, hard 

novaculite is present in most if not all places, this part of the formation becomes less calcareous and more siliceous northward in the 

quadrangles, and in some localities it consists entirely of novaculite 

like that in the basal division of the formation. 

The microscopic study of thin sections of the novaculite shows 

that the calcite occurs as small rhombohedra and irregular-shaped 

aggregates, which are embedded in what may be considered a finegrained groundmass consisting entirely of cryptocrystalline quartz. 

The calcite contains a trace of magnesium, and some of it has been 

replaced by secondary quartz. The rhombohedra are usually 0.05 

to 0.08 millimeter across and are bounded by straight walls in which 

the quartz granules are packed like a course of masonry, none being 

included in the calcite. Away from the walls of the rhombohedra, 

the small quartz grains are arranged irregularly but without any 

pore space between them. They are angular and generally average 

less than 0.1 millimeter across, though a few widely separated grains 

.are much larger and have rounded outlines. The fine grains are not 

cemented but, as Griswpld states, seem merely to be jammed together, 

the tenacity of the stone apparently being due to the interlocking of 

the irregular edges of the grains.

The Indians used the novaculite extensively for their stone implements. Many tools made of this rock are found in these quadrangles 

as well as in adjoining areas, .and the old workshops along the 

streams where they were fashioned can still'be identified.' Most of 

the material used was quarried from the massive novaculite at the

33 Honess, C. W., Geology of the Southern Ouachita Mountains of Oklahoma: Oklahoma 

 Geol. Survey Bull. 32, pp. 113-114, 137, 1923.

6242 29 «-5
54 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

base of the formation, but some implements were made from the 

well-rounded novaculite pebbles found in the Cretaceous and later 

deposits of the Coastal Plain.

The following section of the Arkansas novaculite was measured 

in Caddo Gap, where the strata dip 80° S.:

Section of Arkansas novaculite on east side of Caddo River at Caddo Gap

Ft. in.

Stanley shale: Buff shale with subordinate amount of dense, finegrained siliceous yellow stone in thin layers. Fragments of novaculite conglomerate were observed several feet south of this outcrop. 

On the slope on the west side of Caddo River boulders of this conglomerate are thick on the slope, their parent bed being in buffcolored shale ___________ 40

Arkansas novaculite: 

Upper division 

Dark-colored dense novaculite in two layers 1 10 

Concealed_______________________________ 1

Massive white novaculite in beds ranging in thickness from a 

few inches to 3 feet. Much of it is dense and hard, though 

most of it is porous and soft, crumbling into a white powder 

when struck with a hammer. Slickensides were observed 

0 near the middle of the bed________ __ ___- 115 

Middle division 

Buff to red, though at the top somewhat greenish shale con- . 

taining minute yellow specks and many thin layers of dense - 

light-colored novaculite, which is in part laminated____ 11 

Thin-bedded, dense, black novaculite. Interbedded shale is 

in subordinate amount at base, but nearer the top it predominates_________. _______ _____ 14

Layer of black, dense novaculite, the lower half of which is 

a minutely pebbled conglomerate and contains numerous

conodonts_______ 6

Black, dense, thin-bedded, laminated novaculite with subordinate amount of drab, interbedded shale____________- 21 

Black, minutely pebbled novaculite conglomerate containing: . 

numerous conodonts-_ _________ . ________._____ 1

Black, dense novaculite and dark-colored. shale________ 2 

Concealed___________________1____________ 65

Black and greenish-gray clay shale with a few thin layers of 

dense novaculite. Conodonts, linguloids, and sporangites 

were collected from thin layers in this bed__________ 19 

Dense black novaculite in thin layers, some 1 foot thick. Some 

of the layers have, poor cleavage and others are finely lami- 

, nated with parallel black and white bands; a few contain 

sand. Black shale in thin layers alternating with those of 

the novaculite makes up half or nearly half of this bed. 

The'strata are Intensely jointed .and are somewhat contorted, so the actual thickness would be less than here indicated___________.__________,,_____,______ 230

... - Concealed_*._-_^_^_; .__:______________: __ ___ i
STRATIGRAPHY 55

Arkansas novaculite Continued.

Lower division Ft. in.

Much jointed, white, dense, novaculite. Bedding can not be 

detected because of joints. An exposure of 40 to 45 feet at 

one place is apparently an exposure of a single massive bed. 

Slickensides are common in places. At the top, which is 

toward the south, the 'novaculite is brecciated, the fragments being cemented together and partly replaced by 

limonite. A coating of manganese oxide is common along 

the joints___ _ __ 115

White dense novaculite in massive beds, some about 10 feet 

thick. In places thin lenses wedge in between the thicker 

beds. The whole is much jointed. Small oval cavities and 

fine laminations are present in some layers. At the top 

there are thin coatings of manganese oxide along the joints. 

Some of these coatings are small concentric rings_______ 215

Yellow hard shale interbedded with probably an equal amount

of dense, white to yellow novaculite in thin layers ___- 29 

Dense white novaculite, most of whose beds are less than a 

foot thick. The top bed is 3 feet thick and in its upper 2 

or 3 inches are subangular to angular pebbles or fragments 

of novaculite__________________________ 35> 

Black and buff shale interbedded with thin layers of dense 

novaculite____ __________ _________ 1ft

Missouri Mountain slate: Red and buff slate. 

891 5

Origin of the novacuMte. The following summary, partly taken' 

from Branner,28 is sufficient to show the various theories advanced to> 

explain the origin of the novaculite. The most comprehensive papers, 

are those by Griswold, Rutley, and Honess, which are cited below.

Owen 24 considered the novaculite a metamorphosed sandstone1. 

Branner 25 suggested that the compact novaculite may be metamorphosed chert. Comstock 2G regarded many of these rocks as hotwater deposits. Griswold 27 regarded the novaculite as a sandstone of 

extremely fine grain and maintained that the very argillaceous shale 

associated with the novaculite grades into siliceous shale and then 

into transparent novaculite, and that it is therefore shale minus the 

argillaceous component. Rutley,28 in a review of the subject, reached 

the conclusion that the novaculite has resulted from the replacement

23 Branner, J. C., On the Origin of Novaculites and Related Rocks: Jour. Geology, vol. 

6, pp. 368-371, 1898.

24 Owen, D. D., Second Report of a Geological Reconnaissance of the Middle and Southern 

Counties of Arkansas, pp. 23-25, 1860.

« Branner, J., C., Arkansas Geol. Survey Ann. Rept. for 1888, vol. 1, p. 49 [footnote], 

1888.' .

28 Comstock, T. B., Report upon Preliminary Examination of the Geology of WesternCentral Arkansas: Arkansas Geol. Survey Ann. Rept. for 1888, vol. 1, pp. 95 and 129,.1888.

37 Griswold, L. S., Whetstones and the Novaculites of Arkansas: Arkansas Geol. Survey 

Ann. Rept. for 1890,. vol. 3, 1892.

28 Rutley, Frank, On the Origin of Certain Novaculites and Quartzites: Geol. Soc. London Quart. Jour., vol. 50, pp. 377-392, 1894.
56 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

by silica of dolomite or dolomitic limestone. Hinde,29 on hearing 

Rutley's paper, expressed the opinion that the rock is of organic 

origin. Derby 30 held the view that it is the product of a replacement 

of limestone by silica. Weed 31 expressed the opinion that it was 

formed as a chemical precipitate in a deep sea and that although it 

has been hardened it has otherwise been very little altered. Van 

Hise 32 was inclined to believe that it may be largely an organic precipitate, although now completely recrystallized so as to be composed 

of perfectly fitting granules of quartz. C. L. Baker,33 who has 

studied the Arkansas novaculite and the Caballos novaculite of the 

trans-Pecos region of Texas, which is regarded by E. O. Ulrich as of 

Onondaga age and therefore equivalent to the lower division of the 

Arkansas novaculite, says: " In the field, in the hand specimen, and 

under the microscope I found nothing that I could consider as doing 

anything but support Branner's view that the novaculites are simply 

metamorphosed cherts." Honess,34 who has made a thorough study 

of the Arkansas novaculite in McCurtain County, Okla., found 

volcanic ash in the formation in exposures near Wright City. From 

the occurrence of the ash he suggests that at least some of the novaculite is silicified and devitrified volcanic ash, but in the absence of 

positive evidence for proving the suggestion he believes that the novaculite was formed by chemical precipitation, without the aid of 

organisms.

The opinion held by the authors of this report and the basis for 

it may be stated as follows: The rounded, translucent grains of quartz 

that may be seen with the aid of a pocket lens in about equal numbers 

in both the highly calcareous novaculitei and in the interbedded nonmagnesian limestone found in the upper division of the formation 

near the Arkansas-Oklahoma line west of Grannis, Polk County, 

Ark., are obviously detrital. Such grains make up the small amount 

of sandstone found in the novaculite, and the microscope shows that 

they are also sparsely disseminated through the chalcedonylike 

novaculite that constitutes the bulk of the formation. But the closefitting arrangement of the grains of cryptocrystalline quartz in the 

highly calcareous and the chalcedonylike novaculite, which grade 

into each other, and the absence of any cementing material in

29 Hinde, G. J. (discussion of Rutley's paper) : Geol. Soc. London Quart. Jour., vol. 50, 

pp. 391-392, 1894.

30 Derby, O. A., Notes on Arkansas Novacullte: Jour. Geology, vol. 6, pp. 366-368, 1898.

31 Weed, W. H., Geological Sketch of the Hot Springs District, Ark.: 57th Cong., 1st 

sess., S. Doc. 282, p. 84, 1902.

"a Van Hise, C. R., A Treatise on Metamorphism: U. S. Geol. Survey Mon. 47, p. 853. 

1904.

33 Davis, E. F., The Radiolarian Cherts of the Franciscan Group: California Univ. Dept. 

Geology Bull., vol. 11, No. 3, p. 334, 1918.,

M Honess, C. W., Geology of the 'Southern Ouachita Mountains of Oklahoma: Oklahoma 

Geol. Survey Bull. 32, pp. 138-139, 1923.
STEATIGRAPHY 57

these rocks indicate that the fine-grained quartz in them is not of 

detrital origin. In other words, the novaculite is not a fine-grained 

quartzite but a chert. The absence of indications of any such pronounced regional metamorphism in the Ouachita region as would be 

necessary to have produced quartzite of a texture like the novaculite 

further supports this view, because if such metamorphism had occurred surely much of the sandstone of the region would also have 

been changed to a quartzite as dense as the novaculite.

That the silica which formed this quartz was deposited in the sea 

simultaneously with the other material of the formation seems evident, because the novaculite is overlain, underlain, and in part interbedded with beds of clay shale so impervious that they would have 

prevented the free circulation of the underground water necessary to 

introduce from other sources the large amount of silica required as 

replacement material. To be sure, the extensive jointing of the 

shales has made them somewhat pervious, so that in places the underground water circulates in them freely, but the usual even distribution 

of the silica everywhere in any particular layer or bed of the novaculite precludes the possibility that it was introduced subsequent to - 

the jointing. Besides, the jointing of the novaculite beds themselves 

shows that these beds were siliceous when the jointing took place.

The silica may have been derived from siliceous organisms, or from 

chemical precipitates, or from both. No remains of organisms, such 

as those that have contributed their silica to the formation of certain 

cherts in other parts of the world, have been found in the novaculite. 

Their apparent absence would seem greatly to reduce the possibility 

of such a source for the silica, for if the remains of such organisms 

were ever present it does not seem probable that the solution and 

recrystallization of the silica and calcite would have destroyed them 

everywhere in an area so large as that occupied by the novaculite. 

The authors therefore believe that the silica for the novaculite was 

deposited in the sea by chemical precipitation.

Age and strcotigraphic relations. The Arkansas novaculite conformably succeeds the Missouri Mountain slate, but a conglomerate 

of local distribution at its base in Arkansas and Oklahoma indicates 

emergence in at least a small area before or during the early part of 

Arkansas novaculite time. The formation is unconformably succeeded by rocks of Carboniferous age in the quadrangles herein 

described by the Stanley shale, but in much of the Hot Springs 

district and in adjoining areas by the Hot Springs sandstone, which 

is a lenticular formation underlying the Stanley. This unconformity is shown by the apparent thinning out of the beds at the 

top of the novacul,ite near Hot Springs and by a heavy conglomerate of wide though not general distribution at the base of the 

Carboniferous rocks at and near Hot Springs.
 58 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

The only fossils thus far found in the formation in Arkansas 

comprise silicified wood and a single collection of many conodonts 

from a minutely pebbled novaculite conglomerate and of conodonts, 

small linguloids, and sporangites in associated shale. These have 

been obtained from the middle division of the formation. The 

wood was found at two localities near Glenwood. The other fossils 

were procured at Caddo Gap, and upon them Ulrich bases the 

opinion that the middle and perhaps also the upper division are 

to be correlated with the Woodford chert in the Arbuckle Mountains and with the Chattanooga shale. He believes, however, that 

a small part of the middle division is of the same age as the Genesee 

shale of the Appalachian region. He assigns the Woodford and the 

Chattanooga to the Mississippian series, and he accordingly assigns 

to this series these two divisions of the Arkansas novaculite, with 

the exception of the*part of Genesee age; but the United States 

Geological Survey classifies the Woodford chert and the Chattanooga shale as Devonian (?). As the whole of the Arkansas novaculite is still treated as a unit the lower part of which is Devonian, 

'its middle and upper divsions are also tentatively assigned to that 

age. Ulrich 3S stated in 1911 that the Arkansas novaculite "can 

not be younger than the Waverlyan and is most probably much 

older that is, T)riskanian." From a study of fossils collected by 

him from novaculite beds resembling the Arkansas novaculite near 

Ti, Okla., he now holds that only the lower division, which he regarded as Oriskany in 1911, is of Onondaga (Middle Devonian) age. 

The novaculite beds near Ti underlie a bed of chert, which not only 

holds the same stratigraphic position as the Woodford chert of the 

Arbuckle region but has precisely the same lithologic character.

Ashley 36 has expressed the view " that the novaculite of Arkansas 

was deposited at the same time as the Camden chert of Tennessee and 

the Clear Creek chert of Illinois, and is of the same age." The 

authors of this report have also held this view, because the Camden 

chert in its color, hardness, luster, density, fracture, and fineness of 

grain resembles to a marked degree some of the more calcareous 

stone of the Arkansas novaculite, especially that in the upper division. Moreover, this opinion is apparently supported by the facts 

that novaculite is not a common rock and that the Arkansas novaculite and Camden chert are not distantly separated. No stratigraphic 

or other evidence is known which militates against this view except 

that of the above-mentioned fossils from the middle and upper 

divisions of the formation. If these fossils indicate Upper Devonian

86 Ulrich, E. O., Revision of the Paleozoic Systems: Geol. Soc. America Bull., vol. 22, 

p. 477, 1911.

88 Ashley, G. H., The Camden Chert An Ideal Road Material: Resources of Tennessee, 

vol. 1, pp. 42-43, 1911.
STRATIGRAPHY 59

age for the middle and upper divisions of the formation, it follows 

that only the lower division, which contains the greatest amount of 

typical novaculite and which at least locally has an unconformity at 

its top, is of the same age as the Camden chert. This conclusion 

is thus the same as that of Ulrich.

Schuchert 37 in 1908 regarded the Camden chert as being of Oriskany age and the same opinion has been held by Ulrich 38 and by 

Pate and Bassler; 89 but Dunbar,40 who has recently studied the 

Devonian rocks, including their faunas, in western Tennessee, concludes that the typical Camden chert is of Onondaga and not of 

Oriskany age. Furthermore, Dunbar 41 has differentiated and named 

as formations certain rocks that formerly have been included in the 

lower part of the Camden chert. The oldest of these formations

(named by him the Decaturville chert) he regards as being of Helderberg age; the next (his Quail limestone), as of Oriskany age; and the 

youngest (his Harriman chert), as of Oriskany age. The Camden 

chert as restricted by Dunbar and the chert he designates the Harriman chert are described by him as really being novaculite, and it is 

these two formations that the authors observed at various places in 

Tennessee and regarded as having much the same lithologic character 

as the Arkansas novaculite. Ulrich concurs in Dunbar's conclusions 

regarding the age of these cherts and thus correlates the lower part 

of the Arkansas novaculite with the Camden chert as restricted by 

Dunbar.

A single fragmentary specimen of Leptocoelia flabellites has been 

found by Honess at the top of the lower division of the novaculite 

formation on Bog Springs Mountains, 150 paces north of the south 

quarter corner of sec. 5, T. 3 S., R. 27 E., Oklahoma.42 The locality 

is on the west border of the De Queen quadrangle. This species is 

a characteristic Devonian form and is stated by Dunbar to be very 

common in the Camden chert.

CARBONIFEROUS SYSTEM

MISSISSIPPIAN SERIES

STANXBY SHALE

Definition. The Stanley shale took its name from the village 

of Stanley (formerly spelled Standley), in Pushmataha County,

87 Schuchert, Charles: The Paleogeography of North America: Geol. Soc. America Bull., 

vol. 20, p. 544, 1910.

88 Ulrich, E. O., op. clt., pi. 28.

"» Pate, W. F., and Bassler, R. S., The Late Niagaran Strata of West Tennessee: U. S. 

Nat. Mus. Proc., vol. 34, p. 427, 1908.

40 Dunbar, C. 0., Stratigraphy and Correlation of the Devonian of Western Tennessee; 

Tennessee Geol. Survey Bull. 21, pp. 88-90, 1919.

« Idem, p. 33.

a Honess, C. W., Geology of the Southern Ouachita Mountains of Oklahoma: Oklahoma 

Qeol. Survey Bull. 82, p. 117, 1923.
60 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Okla. It consists mainly of shale, though it contains much sandstone and a little tuff and conglomerate. The thickest bed of tuff, 

which is near the base, has been mapped and is herein described as 

the Hattpn tuff, lentil, taking its name from the village of Hatton, 

in the De Queen quadrangle, where it is excellently exposed. In 

places shale at the base has been changed to a slate that was formerly 

called the " Fork Mountain slate," from Fork Mountain, where it is 

well developed.44 The Stanley belongs to the Carboniferous system, 

and represents a part of the Mississippian series. Except the tuff 

and conglomerate none of the beds have distinguishable characteristics. On this account and because the formation is much folded, the 

exact determination of the thickness is impossible, but an approximate thickness of 6,000 feet was measured from 1 to 2 miles southwest 

of Glenwood, in the Caddo Gap quadrangle.

Distribution. The Stanley shale is the surface rock in the Mazarn 

and Cove Basins, over most of the Athens Plateau, and in the narrow 

valleys in the mountainous districts an area of outcrop much larger 

than that of any other formation^ The sandstone of the Stanley 

weathers so easily that it nowhere produces prominent ridges. In 

fact, the formation is exposed only in valleys, basins, or low plateaus.

Character. The shale that constitutes the greater part of the formation is argillaceous, though much is sandy; it breaks into thin, 

hard plates with smooth glossy surfaces showing small mica flakes, 

and in most places it is bluish black but in others black. Here and 

there at the base it is carbonaceous enough to blacken the fingers 

when they are rubbed over fresh surfaces. The dark colors prevail 

along most of the streams and in the deeper artificial exposures 

where the shale is not weathered, but the colors usually seen along 

the roads and in other exposures away from the streams are green, 

yellow, or brown, the shale in such places having been weathered. 

The shale is much crumpled in fact, the crumpling is so great 

in places that the bedding can not be made out except where sandstone layers are exposed. Joints cut the shale in all directions, 

and many of them are occupied by quartz veins. Kesidual quartz 

from these veins occurs in sufficient quantity to whiten the surface 

in some of the more level parts of the country, as around Blanchard, 

Grannis, Wickes, and Van.dervoort. Most of the veins are a fraction 

of an inch thick, but some, are more than 1 fo;ot thick; a few that 

have the same strike as the folded strata can be traced for a mile 

or more. Quartz is usually the sole mineral occupying these veins, 

though other minerals, among which are lead, zinc, and. antimony 

minerals, occur at a number of places in the De Queen quadrangle. 

The metallic minerals just mentioned have been mined from time 

to time near Gillham. '" 

"Purdue. A. H., The Slates of Arkansas: Arkansas Geoi. Survey, 1909
STBATIGBAPHY 61

The final product of weathering of the shale is a yellow or red 

clay that is only a few inches thick in most places.

In parts of the northeast corner of the De Queen quadrangle and 

in the adjoining part of the Caddo Gap quadrangle shale at the base 

of the formation as much as 150 feet thick has been changed to a 

slate, to which, as previously stated, the name " Fork Mountain 

slate " has been applied. In some places the fresh part of this slate 

is dark gray, with here and there a thin black layer, and in others 

it is black throughout, whereas the exposed portion, which usually 

forms small bluffs, is reddish and yellow. The parts so altered are 

similar to weathered parts of the Missouri Mountain slate. Slaty 

cleavage is so well developed that the slate easily splits in thin sheets, 

and slate quarries have been opened in it, but much crumpling and 

the abundance of joints, including, both dip and strike joints, render 

most of the bed worthless for commercial slate. In some localities 

thin flinty layers, many of which resemble novaculite, and a few 

layers of quartzite are present. These layers occur in greatest numbers at the base of the formation, not only where the shale has been 

altered to slate but elsewhere. They reach a thickness of 15 inches, 

but the most common thickness is 2 to 3 inches.

Sandstone constitutes about one-fourth of the formation and although it occurs throughout the formation, there is more in the lower 

and upper parts of the formation than in the middle. The fresh 

rock is hard, tough, compact, quartzitic, rather fine grained, and 

greenish or bluish gray and occurs in layers as much as 18 feet thick, 

most of which are interbedded with some shale, though numerous 

successive layers aggregating several hundred feet in thickness are 

interbedded with little shale. Only a few beds have a light-gray 

color. At places near the top and base of the formation some of the 

quartz grains of which the sandstone chiefly consists are larger than 

usual, and therefore some of the sandstone is coarse grained, and 

some is even millstone grit. The grains are mainly angular, though 

some are rounded. Besides quartz the minerals that are present, as 

determined through microscopic examination of thin sections, are 

 prthoclase, plagioclase, microclino, tourmaline, calcite, pyrite, magnetite, zircon, and chlorite. Chemical tests show that a phosphate, 

probably apatite, is also present but in small amount. Some of the 

feldspar grains are fresh, but the others are altered to kaolin. Quartz 

is the cementing material, and some grains of that mineral are enlarged by secondary; quartz. The sandstone, like the associated 

shale, contains thin quartz veins, a few of which carry calcite.

So readily does the sandstone break down on weathering that it 

forms few prominent ridges, and very little shows on the surface 

except along the roads and streams. The altered .sandstone is soft,
62 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

porous, more or less earthy, and green, yellow, or brown. Weathering has reached to the greatest depths in the more level areas, but 

even there the hard, unaltered rock is usually only a few feet below 

the surface. Besides soil, the material above the hard rock in those 

areas consists mainly of white or cream-colored sandstone that is soft 

enough to crumble between the fingers, though such sandstone contains a few unaltered boulders and some thin streaks of'limonite. 

(See pi. 7, B.) Most of the sandstone boulders found on the surface have weathered by exfoliation like igneous rocks and have become rounded. If such boulders are broken open the weathered 

portion of many of them is found to be merely a thin though sharply 

defined surficial zone inclosing unaltered rock.

In some parts of the quadrangles a bed of conglomerate ranging in 

thickness from a feather edge to 15 feet rests upon the Arkansas 

novaculite, and in places there is a similar conglomerate that is 

separated from that formation by 20 to 75 feet or more of shale. 

These conglomerates consist of dark and light colored angular to 

subangular pebbles of novaculite embedded in a matrix of dense 

siliceous material resembling novaculite.

A bed of dense black chert 2 to 6 inches thick occurs in the formation, probably near the middle.

Widely separated layers, lenses, and nodules of phosphate rock, 

whose greatest observed thickness is 1^ inches, occur in shale in the 

basal part of the formation, both above and below the Hatton tuff 

lentil, in the vicinity of the Cross Mountains. A few small nodules 

of phosphate were seen near Gillham, but these are probably near the 

middle of the formation. This rock is black, has a rather high 

specific gravity, and weathers to a white or yellow color on exposed 

surfaces. Its fracture ranges from platy and uneven to conchoidal. 

Chemical analyses of two samples show that they contain 6.08 and 

10.56 per cent of phosphorus pentoxide, which is equivalent to 13.28 

and 23.07 per cent of tricalcium phosphate, respectively.

A number of beds of tuff, all of which are very similar in lithologic 

character, occur near the base of the formation in the northern and 

western parts of the De Queen quadrangle. The chief difference 

between them and the sandstone of the Stanley is that they contain 

much feldspar in large grains and the sandstone only a small quantity 

of this mineral. According to Williams 45 these beds were first observed and noted by J. Perrin Smith and were afterwards examined 

by K. A. F. Penrose, jr. Williams, who studied hand specimens and 

thin sections, states in his brief description of the rock that it contains 

much detrital igneous material, and he called it the "Polk County

48 Williams, J. F., The Igneous Rocks of Arkansas: Arkansas Geol. Survey Ann. Kept, 

for 1890, vol. 2, pp. 375-376, 1891.
STEATIGBAPHY 63

ash bed." The tuff has been observed by other geologists, who have 

applied the names " igneous rock," " tuff," " basic igneous dikes," and 

" graywacke " to it. The tuff is here described only briefly. A full 

description of the tuff in McCurtain County, Okla., is given by 

Honess 46 in a report which was published after the present report 

was written.

The lowest and thickest of the tuff beds is the Hatton tuff lentil. 

The distribution of this lentil and the partial distribution of the 

thinner beds are represented on Plate 3. The Hatton tuff is exposed 

in or near the Cross Mountains and within a small area at the west 

end of the ridges in the northeastern part of the De Queen quadrangle. Farther east and north it loses its distinguishing characteristics and changes to a sandstone not unlike other sandstones in the

Stanley shale. A change of the tuff to sandstone may be seen in a

hand specimen, even where the tuff is typically developed. The 

exposures are narrow bands, which are marked in many places by 

low ridges but in others by no distinctive topographic feature. 

Although rock ledges are numerous, only a row of large, exfoliated, 

spherical boulders indicates the existence of the underlying tuff at 

many places. Notwithstanding this the tracing of the bed across the 

country is rather difficult on account of the dense undergrowth of 

young timber usually found in this region. The best outcrop is in 

the railroad cut half a mile south of Hatton, where the lentil was 

first observed by the authors. (See pi. 8, B.}

The Hatton tuff in and near the Cross Mountains is usually 90 

feet thick, but at the west end of the mountains, in the northeast 

corner of the De Queen quadrangle, it is much thinner and probably 

does not exceed 30 feet, which is the thickness at Gillham Springs. 

At Hatton it is separated from the Arkansas novaculite by about 140 

feet of shale containing some argillaceous sandstone. Farther northeast the beds between the Hatton tuff and Arkansas novaculite are 

much the same in thickness and character as they are at Hatton, but 

southwest of Hatton they are thicker, probably 300 or 400 feet, and 

contain a larger proportion of sandstone. They contain the previously described beds of conglomerate that are near the base of the 

Stanley, and they are of the same age as the slate of the Stanley that 

has been called the " Fork Mountain slate."

There are two and possibly three or four of the thinner beds, which 

range in thickness from 6 to 40 feet. They all dip at high angles and 

crop out as east-west bands only a few paces wide. None of them 

can be followed more than a few miles, owing to the thinning out 

of the beds, to the lack of continuous exposures, and to their changing

<8 Honess, C. W., Geology of the Southern Ouachita Mountains of Oklahoma: Oklahoma 

Geol. Survey Bull. 32, pp. 139-202, 1923.
64 DE QUEEN" AND CADDO GAP QUADRANGLES, ARKANSAS

to sandstone, with which they are usually associated. The two belts 

that were traced the greatest distance are exposed in and near the 

village of Cove. They are the outcropping edges of the same bed, 

30 to 40 feet thick, and are exposed in a closely compressed anticline. 

The northern belt, which extends through the village, is the northern 

limb of the anticline, and the southern belt, which passes a little less 

than a quarter of a mile to the south, is the southern limb. About 500 

feet of shale and sandstone beneath the tuff is exposed at Cove without revealing the Hatton tuff below.

All the tuffs, including the Hatton tuff, are similar in lithologic 

features. They are so massive and homogeneous and their joints are 

so well developed that if bedding planes exist they are, in most if not 

all places, confused with the joints, but the bedding can be determined 

by the parallel arrangement of numerous green, flattened pellets of 

chloritic material that are usually present in some parts of the beds. 

The color of the unweathered rock is dark gray with a greenish 

tinge, but that of the weathered rock, which consists of a layer 

usually less than an inch thick over the surface of the exposed parts, 

ranges from light greenish gray on the surface to brown next to the 

fresh portion. The rock is tough and compact and like other beds 

in the Stanley contains quartz veins, but the veins seem more numerous in the Hatton lentil than elsewhere in the Stanley. In its macroscopic character it strikingly resembles a porphyritic igneous rock. 

The largest conspicuous grains are feldspars, which are usually 2 

millimeters or less in diameter, but some are as much as 5 to T millimeters. (See pi. 8, A.) On weathering, the grains of feldspar kaolinize and become white, giving the rock a spotted appearance. Other

minerals that occur in various amounts and mostly in grains of microscopic size are quartz, muscovite, magnetite, pyrite, zircon, apatite, 

chlorite, calcite, and kaolin. E. S. Larsen, who has studied thin 

sections of the tuffs, states that they are composed largely of devitrified and silicified volcanic glass, of which a large part is ordinary 

volcanic ash consisting of fragments of the walls of bubbles, though 

some of the larger fragments of glass are fluidal. The original rock 

from which the tuff was derived, Larsen states, was probably near a 

rhyolite or quartz latite.

Strcttigraphic relation^. In the Caddo Gap and De Queen quadrangles the Stanley shale succeeds the Arkansas novaculite, whose 

upper part is tentatively assigned to the Devonian system, but in 

parts of the Hot Springs district it conformably succeeds the Hot 

Springs sandstone, which is there a lenticular formation resting upon 

the novaculite and forming the base of the Carboniferous system. 

An unconformity at the base of the Carboniferous rocks is indicated 

(1) by the occurrence of a conglomerate as much as 35 feet thick at
STRATIGKAPHY 65

the base of the Hot Springs sandstone, (2) by the occurrence of a 

conglomerate beneath the Stanley shale at places in the De Queen 

and Caddo Gap quadrangles, and (3) by the fact that the Stanley 

rests upon the Bigfork chert, of Ordovician age, at places in the 

Mount Ida quadrangle, which adjoins the Caddo Gap quadrangle 

on the north. Although an unconformity occurs at the base of the 

Carboniferous rocks, the erosion surface over which the sea of that 

period transgressed was very,even to judge from the rather uniform 

thickness of the top strata of the novaculite in the quadrangles here 

described.

The Stanley is conformably overlain by the Jackfork sandstone, 

which is in turn overlain in these quadrangles and other parts of 

the Ouachita Mountain region of Arkansas by the Atoka formation.

However, in parts of the Ouachita region of Oklahoma the Caney 

shale, which in places is overlain by the Wapanucka limestone and 

this in turn by the Atoka formation, rests upon the Jackfork sandstone. In the Arbuckle Mountain region of Oklahoma both the 

Stanley and the Jackfork are absent, and the Caney shale usually 

rests upon the Woodford chert, with which the middle and upper 

divisions of the Arkansas novaculite are herein correlated, but over 

part of the Arbuckle region the Sycamore limestone intervenes between the Woodford and the Caney, being thickest in the west and! 

dying out entirely in the east. The few known localities in the 

Ouachita region where the Caney does not rest upon the Jackfork 

are near Ti, in the southern part of the McAlester quadrangle. There 

the Sycamore, the Stanley, and the Jackfork are all absent, and the 

Caney rests directly upon the Talihina chert, whose uppermost beds 

correspond in age and lithology to the Woodford chert and alsa 

to the middle and upper parts of the Arkansas novaculite.

Fossils and correlation. Although the Stanley shale attains a 

thickness of 6,000 feet and is widely distributed in the Ouachita 

Mountain region, it has so far yielded only a few fossil plants and 

invertebrates. The overlying Jackfork sandstone, of equal extent 

and thickness, has yielded no determinable invertebrate fossils, but 

the Caney shale, which rests upon the Jackfork in parts of Oklahoma, has supplied a rather large invertebrate fauna, some fish remains, and a few plants. The Jackfork sandstone, the Stanley shale, 

and the lower part of the Caney shale are classed as Mississippian 

and the upper part of the Caney shale as Pennsylvanian, by the 

United States Geological Survey. Differences of opinion have, however, existed and still exist among geologists concerning the age 

of these formations. When the Jackfork sandstone and Stanley shale 

were first described 47 they were classed as Ordovician. Now they and

*7 Taff, J. A., U. S. Geol. Survey Geol. Atlas, Atoka folio (No. 79), 1902.
66 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

the Caney shale are placed in the Carboniferous system by all geologists, but are believed by some to belong to the Mississippian series 

and by others to the Pennsylvanian series. The opinions of different 

geologists who have studied fossils from the Caney, Jackfork, and 

Stanley formations are presented in the next few pages.

David White furnishes for this report the following statements 

concerning a number of plant collections from the Caney, Jackfork, 

and Stanley formations in Oklahoma:

Most of the collections are designated by the lot numbers used in the paleobotanic work of the Geological Survey at the National Museum.

3911. Impure limestone fragments collected by Taff and others from Caney 

shale:

Lepidodendron sp. suggestive of L. brownii. 

3952. Caney shale:

Vermicular traces of algae or borings, probably of no present value.

3910. Ramentum, possibly of Psaronius, associated with very small seeds, 

probably Trigonocarpum.

3911. SW. % sec. 2, T. 1 S., R. 16 E., Antlers quadrangle. Black shale in 

valley of Caney Creek:

Calamitean stem base of pre-Pottsville aspect.

3912. Tributary of Ellen Creek, just north of Ti post office, northeast corner 

of sec. 20, T. 3 N., R. 16 E.:

Asterocalamites, probably A. radiatus.

6240. Eight miles east of Atoka. Collected by White. Jackfork? (probably 

Stanley):

Asterocalamites, probably A. radiatus. 

Stigmaria with small scars. 

Lepidophloios? decorticated, indeterminable twigs.

These fragments have a lower Carboniferous aspect, but the evidence is 

inconclusive. 

5669. Bast-northeast of Tuskahoma, foot of Kiamichi Mountain:

Lepidodendron sp., indeterminable.

Lepidodendron veltheimianum, as described from the Carboniferous limestone by earlier authors.

Sphenophyllum sp. (probably), indeterminable. 

Sphenopteris sp., indeterminable. 

Asterocalamites scrobiculatus (equals radiatus).

5508. NE. % NE. *4 sec. 32, T. 2 N., R. 20 E., lower part of heavy black shale, 

in creek bed. Stanley (?) :

Asterocalamites scrobiculatus. 

' Asterophyllites?

Sphenopteris cf. S. larischii.

Fern stem (Aneimites?).

Lygenopteris sp.?

Trigonocarpum sp.

Sphenopteris sp., Mississippian aspect, indeterminable.

A collection of plants was obtained by Mr. Miser in 1914 and 

1923 from the top of the Stanley shale in the Whitley railroad cut 

2% miles by road south of Gillham and 1 mile southwest of 

King. (See pi. 9, A.) This collection was also examined by David
STBATIGKAPHY 67

White and is said by him to contain the best fossil plants that havQ 

come to his attention from the Stanley and Jackfork formations. 

He has supplied the following statement and list of species:

Sphenopteris cf. S. schimperiana.

Sphenopteris cf. S. quercifolia.

Sphenopteris cf. S. goepperti.

Sphenopteris cf. S. sphyropteris.

Sphenopteris cf. S. vespertinus or bifida.

Aneimites?, stem.

Neuropteris antecedens?

Asterocalamites scrobiculatus.

Calamites sp. with wide ribs.

Sphenophyllum cf. S. tenerrimum, with very small leaves.

Lycopod stem, obscure, phyllotaxy verticillate in aspect.

Carpolithes, very small, species probably new.

Carpolithes cf. C. siliqua.

Trigonocarpum, small, coronate, same as at other localities.

Trigonocarpum cf. T. parkinsoni?

Rhacopteris?, sp., fragment possibly from the basal portion of a leai

of this genus.

The fossils in this collection have been subjected to wave attrition and have 

been reduced to very small fragments, most of which are somewhat macerated 

as well as torn.

Asterocalamites scroUculatus and another calamarian stem comparable to 

Calamites roemeri are most numerous in the collection. With these are plant 

fragments, better described as ragged scraps, including Sphenopteris, probably 

8. goepperti or possibly 8. refracta (which may be identical with goepperti) ; 

Rhacopteris? or Adiantites; a Rhodea or Rhacopteris, probably identical with 

R. moravica; Sphenopteris cf. S. schimperiana and Sphenopteris cf. S. quercifolia, together with another Splvenoptei-is, possibly S. biftda. The Trigonocarpums are comparable to T. conchaeforme and a new species found in the Floyd 

shale of Alabama. Carpolithes siliqua is of doubtful systemic value and is 

best known from the Pocono. Neuropteris antecedens is probably present. 

Sphenophyllum cf. S. tenerrimum as here identified is a more rigid and simpler 

type than that in the Pottsville.

On the whole the plant material, consisting mainly of minute fragments, 

though in part closely related to species known from the Pottsville, appears 

to find a closer relation and some specific identities in the floras described 

from the Carboniferous limestone, probably of Chester age, in the Old World. 

The Lepidodendron quoted as L. veltheimianum is identical with one from the 

Chester of Alabama, in which it is associated with a similar phase of Asterocalamites scrobiculatus.

The discovery of better material will doubtless necessitate a revision of some 

of the tentative [specific] identifications. Possibly such material will show that 

the beds are Pennsylvanian, but the aspect of the plant fragments and the 

apparent relations of the beds strongly suggest that they are Mississippian. 

Accordingly, I am inclined to regard them as Mississippian and to suggest that 

they are of Chester age, but the paleobotanic data available are insufficient to 

justify their conclusive reference to the Mississippian. -

The examination suggests the possibility of the deposition of a great thickness 

of sandstone and shale derived from the north Texas land mass on the south 

during the period of Mississippian uplift and deformation and the concomitant
68 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

early stages of Pennsylvanian subsidence. Further, it is to be noted that marine 

conditions appear to have been absent in the Stanley-Jackfork region during 

most if not all Of the time Of deposition of this great thickness of beds.

Prosser, who collected some fragments of fossil plants from the 

Stanley shale in Hot Springs, made the following statement 48 concerning them: . On one of the olive pieces of shale is a fern pinnule, which is similar to those 

of Sphenopteris. It resembles somewhat the pinnules of -Sphenopteris decomposita Kidston, from the calciferous sandstone (lower Carboniferous) of Scotland, but nothing could be stated positively of such a fragment. Other fragments resemble Corda/ites.

A few invertebrate fossils have been found in the Stanley shale 

by Honess in McCurtain County, Okla. The following statement 

from his report 49 gives .the. opinion of Charles Schuchert concerning 

them: : . With regard to the small marine fauna found on the banks of Little River 

(specimens 943. and-944) and the.inarticulate bracbiopods from the base of the 

Stanley (specimens 1015 and 1016), Professor Schuchert writes as follows:

" It seems to me fairly certain that these specimens can not be other than 

Mississippian or Pennsylvanian. As you got an undoubted Lepidodendron even 

beneath lots 943 and 944 and as the specimen appears to me like a Pennsylvanian 

form., it seems that the.whole of the Stanley and Jackfork may be Pennsylvanian in age rather than Mississippian. The marine fossils do not indicate 

anything to the contrary- Your, marine fossils are as follows:

Orbiculoidea nitida Phillips. Loc. 1015 and 1016. I can not distinguish 

the specimens from Coal Measures forms.

Crinoid columnals. Loc. 943 and 944. Common. At least two species.

Cystodictya, sp. undet. Loc. 943 and 944.

Ehombopora, sp. undet. Loc. 944.

Fenestella, sp. undet. Loc. 944.

Bryozoa. Undet. Common. Loc. 944.

Productus suggesting Pustula nebraskensis. Loc. 943 and 944.

Chonetes, sp. undet. Loc. 943.

Very fragmentary. Finely striate^ form.

'Fish bone. Loc. 943."

The same fossils as those submitted to Schuchert were also submitted to E. 0. Ulrich, who reports in part as follows: 50

The invertebrate part of the evidence by itself would not be conclusive 

either way. The trend of the evidence is toward the Pennsylvanian rather than 

the Mississippian (either early or late). Again there is nothing in the collection that may be justly cited as definitely opposed to correlation of the 

Stanley with lower Pottsville or basal Morrow, which, conclusion I reached 

 in my "Revision"; mainly on physical and diastrophic. considerations. v

The fossils observed by me in the Jackfork, seemed decidedly corroborative 

of my convictions respecting the post-Chester age of the Stanley. So far as

48 Prosser, C. S., Notes on Lower Carboniferous Plants from the Ouachita Uplift: Arkansas Geol. Survey Ann. Kept, for 1890, vol. 3, pp. 423-424, 1892.

48 Honess, C. W., Geology of the Southern Ouachita Mountains, of Oklahoma: Oklahoma 

Geol. Survey Bull. 32, pp. 177-178, 1923, 

M Idem, p. 178.
U. S. GEOLOGICAL SURVEY BULLETIN 808 PLATE 8

A. POLISHED SURFACE OF SPECIMEN OF TUFF FROM THE STANLEY SHALE IN 

THE DE QUEEN QUADRANGLE

Shows the numerous fragments of feldspar flight and dark gray) and the few fragments of other 

rocks (hlack), embedded in a matrix of fine-grained material. Natural size

Ji. HATTOIN TUFF LKVIIL OF STAM.KY SIIAMi, HALF A MILE SOUTH OF

HATTON, ARK.
U. S. GEOLOGICAL SURVEY

A. STANLEY SHALE IN WHITLEY RAILROAD CUT, ZYi MILES SOUTH OF GILLHAM, ARK.Fossil plants were obtained from the shale at 

this locality
STRATIGEAPHY 69

I can see, your new evidence leaves the problem just about where I left it in 

1911 that is, with the probabilities favoring assignment of the Stanley to the 

earlier Pennsylvanian.

Morgan 51 has recently made a study of the Caney shale including 

its fauna in the northern part of the Arbuckle Mountains of Oklahoma. He says:

From the evidence afforded by the fossils the conclusion is here drawn that 

the upper part of the Caney is of Pennsylvanian age and partially equivalent 

to the Morrow formation, and that the lower part is late Mississippian, approximately equivalent to the Moorefield, Fayetteville, and Batesville formations 

of Arkansas.

Eastman,52 who studied fish remains from the Caney shale in 

Oklahoma, stated that the character of such remains tends to support the upper Mississippian age of the Caney.

Some fragmentary casts of shells were found in the De Queen 

quadrangle in a bed of dark greenish-gray millstone grit at the 

base of the Jackfork sandstone, about one-eighth of a mile south of 

an abandoned sawmill site, which is near the north line of sec. 

34, T. 7 S., R. 30 W. A collection from the locality-was'submitted 

for examination to G. H. Girty, whose report follows:

The material contains little besides crinoid segments, which are in considerable abundance. Mr. Frank Springer has kindly examined some of these 

crinoid fragments for me and writes as follows regarding them: " It is. 

impossible even to guess at the geologic age of the crinoid-stem fragments you 

have sent me. I have seen some joints in somewhat similar condition 

in highly metamorphic Carboniferous material in New Mexico, but so far as. 

the crinoid fragments show it might belong anywhere from the Silurian 

to the Trias or Jura."

Among the other forms are fragments of a finely costate shell, which is probably, some species of Productus. Another fragment suggests a species of 

Myalina, but it may not belong to that genus. A third and last type is a. 

tiny fragment of some lunarium-bearing bryozoan suggesting FistuUpora, 

Meek&pwa, or less probably CystoMctyo,. The age of this collection is probablyCarboniferous, but more than this it is impossible to say.

A large fauna has recently been obtained by Honess from two> 

localities in the northwest corner of McCurtain County, Okla., from, 

a thick succession of sandstone Avhich he calls the Jackfork sandstone. The fauna is described 53 by him as a MorroAv fauna and is 

composed of the following species as identified by him:

Zaphrentis gibsoni. 

Aulopora angularis, n. sp. 

Aulopora magna, n. sp. 

Aulopora gracilis.

61 Morgan, G. D., Geology of the Stonewall Quadrangle, Oklahoma: Bur. Geology Bull.. 

2, p. 56, Norman, Okla., 1924.

63 Eastman, C. R., Brain Structures of Fossil ^ishes from the Caney Shales : Geol. Soc. 

America Bull., vol. 24, pp. 119-120, 1913.

Ba Honess, C. W., Geology of Southern Leflor* and Northwestern McCurtain Counties,. 

Okla.: Bur. Geology Circ. 3, Norman, Okla.. 192 L ---

6242 29 6
70 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Polypora sp.

Rhombopora sp.

Many undeterminable forms.

Chonetes arkansanus. . - - Chonetes sp.

Productus cf. P. gallatinensis.

Productus sp. (1).

Productus sp. (2).

Productus sp. (3).

Pustula punctata. '

Pustula moorei, n. sp.

Avonia sp.

Marginifera splendens.

Squamularia transversa.

Rhipidomella pecosi.

Rhipidomella sp.

Schizophoria resupinoides?

Rhynchopora minuta, n. sp.

Girtyella cf. G. emarginata.

Spiriferina transversa.

Spiriferina spinosa.

Spirifer rockymontanus.

Reticularia cf. R. setigera.

Brachythyris laticosta.

Hustedia brentwoodensis.

Hustedia miserl.

Composita subtilita.

Composita wasatchensis..

Composita cf. C. gibbosa.

Edmondia sp.

Nucula anadontoides.

Nucula parva.

Nucula sp.

Leda bellistriata.

Leda rugosa, n. sp.

Parallelodon obsoletus.

Parallelodon tenuistriatus.

Leiopteria jackforkensis, n. sp.

Leiopteria sp.

Conocardium parrishi.

Myalina orthonota.

Schizodus wheeleri.

Aviculopecten cf. A. hertzi.

Aviculopecten halensis.

Aviculopecten sp. 1.

Aviculopecten sp. 2.

Allorisma cf. geinitzi.

Pleurophorus oblongus.

Cypricardella oblonga.

Cypricardella, u. sp. . . Astartella h. sp. 1.

Astartella n. sp. 2.......

Plagioglypta annulistriata. .
71

Pharkidonotus percarinatus. 

Euphemus carbonarius. 

Phanerotrema grayvillense. 

Worthenia? tabulata. 

Worthenia sp. 

Euconospira arkansana. 

Trepospira depressa. 

Euomphalus catilloides. 

Strophostylus cf. S. subovatus. 

Platyceras parvum. 

Zygopleura rugosa.

Meekospira peracuta var. choctawensia 

Meekospira sp. 

* Sphaerodoma intercalaris. 

Sphaerodoma primigenia.

Orestes nodosus.

Conularia crustula.

Orthoceras sp.

Metacoceras cornutum.

Gastrioceras excelsum.

Gastrioceras sp.

Grifflthides sp.

Eupachycrinus cf. B. magister.

Eupachycrinus sp.

Crinoid stems and plates of doubtful genus.

Fragments of wood.

Shark spine.

Concerning the above-listed fauna Honess comments in part as 

follows:

The fauna is regarded as definitely Morrow and equivalent to the Wapanucka.

The Morrow fauna * * * occurs about midway in the sandstone series 

which forms Boktukola syncline. The sandstone series overlies the Stanley 

shale in normal sequence and is 13,618 feet thick. * * * The questions 

arising are: (1) Is the whole section Jackfork sandstone, or is only the lower 

portion Jackfork and the upper part something else? (2) How much of the 

sandstone series may be regarded as Morrow? (3) Where is the Caney shale?

From the point of view of the lithology there is no difference between that 

part of the formation which lies below the fauna and that part which lies 

above it. There is no large body of shales intervening any place in the section 

to form a basis of division, and no part of this vast series looks like or resembles in any way the Caney shale or the Atoka formation. The Wapanucka 

limestone is wanting, and in its stead there are fine-grained ferruginous sandstones. The entire series (13,618 feet thick) is one continuous and uniform 

whole, and this being a fact, the writer does not see fit to do otherwise than 

to speak of a Lower Jackfork (that portion which lies below the Morrow 

fauna) and an Upper Jackfork (that part which lies above it). * * *

The question of the exact limits of the true Morrow is one which can not be 

answered at the present time. We shall have to await the discovery of other 

fossiliferous horizons, lower in the series. As to the Upper Jackfork, it is all 

Pennsylvanian, of course, by the law of superposition, and is, apparently, a 

sandy shoreward phase of the Atoka formation of more northerly latitudes.
72 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Not having discovered the Caney shale in the Jackfork sandstone series, 

it must be much thinner in its southerly development, or possibly wanting 

entirely in the Boktukola syncline. Whether its position is represented by 

some one or more of the thin shaly bands in the Lower Jackfork or to some 

part of the Stanley, if it may be permitted to go that far, is also an unsolved 

problem. It is hoped that some time, somewhere5 the Caney fauna may be 

discovered in the section beneath the Morrow horizon.

Correlating, then, the Wapanucka of the Arbuckle region with the Morrow 

of the Ouachita region, a portion, at least, of the.Upper Jackfork should be 

equivalent to the Atoka formation; and the Caney of the Arbuckles either 

pinches out to eastward and southward or wedges into the Lower Jackfork 

or older sediments somewhere beneath the Morrow. The Woodford of the 

Arbuckle region is regarded as pre-Stanley and probably equivalent to the 

middle division of the Arkansas novaculite, as Doctor Ulrich has pointed out.

The Caney shale, as pointed out by Hohess, is possibly absent ,in 

the localities where he obtained the above-listed fossils, but several 

unpublished maps by J. A. Taff show it to be present farther north 

and west in the Ouachita Mountains of Oklahoma. There it rests 

upon the Jackfork sandstone in large areas, but it rests upon chert 

beds of the same age as the Woodford chert at a few places along the 

north edge of the mountains ,in Oklahoma. It is succeeded in places 

by the Wapanucka limestone and this in turn by the Atoka formation; in other places it is succeeded directly by the Atoka formation. 

At all places in the Ouachita Mountains of Arkansas the Atoka 

rests upon the Jackfork sandstone; the Caney shale and Wapanucka 

limestone appear to be absent there.

As Honess applies the name Morrow to the fossil-bearing beds 

of his Jackfork sandstone and correlates the beds with the Wapanucka limestone, the sandstone (Upper Jackfork sandstone of Honess) 

above the fossiliferous bed is, as pointed out by him, a probable phase 

of the Atoka formation. The question then arises, shall we follow 

lime equivalency or lithologic character in the use of formation 

names? If we are to foljow time equivalency, the Upper Jackfork 

sandstone of Honess could be called Atoka formation and his Lower 

Jackfork sandstone would be the true Jackfork sandstone. The 

Upper and Lower Jackfork sandstones of Honess are designated 

Atoka and Jackfork, respectively, by Mr. Miser on the geologic 

map of Oklahoma recently published by the United States Geological Survey. If Mr. Miser is correct in his conclusions concerning 

the Jackfork sandstone of Honess it follows that the so-called Jackfork fauna obtained by Honess overlies the true Jackfork sandstone.

The following statement w.ith reference to the age of the Caney, 

Jackfork, and Stanley formations has been written by G. H. Girty 

for this report:

The Stanley shale and Jackfork sandstone have thus far furnished few 

invertebrate fossils, or none at all, and consequently the evidence as to their 

geologic age furnished by the formations that inclose them rarely a factor
STRATIGRAPHY 73

that can safely be neglected here takes a place of prime importance. The 

Stanley shale is succeeded in the geologic section by the Jackfork sandstone, 

and that in turn by the Caney shale. If this succession is established, as it 

seems to be, if the two formations themselves furnish only dubious evidence, 

and if the Caney shale is of Mississippian age, as the invertebrate fossils seem 

to indicate, the conclusion is ineluctable that the Stanley and Jackfork are 

Mississippian or older.

The Caney shale contains two very unlike faunas, of which the upper is 

Pottsville in age, and the lower, it is believed, Mississippian. The lower fauna, 

which is the only one that at present concerns this discussion, ranges through 

about 500 feet, beginning at the basal contact with the Jackfork sandstone. It 

is abundant in individuals, especially those belonging to a few species, and 

presents a fair variety of forms, of which 42 were recognized when the fauna 

was originally described. Though in these respects the evidence is favorable 

for purposes of correlation, it .is rendered somewhat ambiguous by the fact 

that the Caney fauna is peculiar and very unlike any of the well-known faunas 

of Carboniferous age, Mississippian as well as Pennsylvania)!. The faunas of 

northern Arkansas and northeastern Oklahoma are, however, intermediate in 

character, as they are intermediate in position between the region which saw 

the development of the typical Mississippian faunas and that in which the 

Caney fauna lived. In this intermediate region are found many species that 

are identical with or closely related to those of the Caney shale, and at the 

same time others that are characteristic of the Chester faunas of the upper 

Mississippi Valley, the two groups of species occurring either directly associated or in distinct but interfingering beds. The rocks in Arkansas containing 

such intermediate faunas have been classified as the Moorefield shale, the 

Batesville sandstone, and the Fayetteville shale and are recognized by all as 

of Mississippian age. These facts are not open to dispute the three formations 

of northern Arkansas are of Chester age, or possibly in part of pre-Chester Mississippian age, and the Caney fauna is more or less closely related to those 

Mississippian faunas, but is not at all closely related to any American fauna 

of known Pennsylvaniah age. On these ground^ the Caney shale was in 1JM)9 

correlated with the Moorefield-Fayetteville interval in the geologic sequence of 

northern Arkansas and identified as Mississippian.

In the intervening years much evidence has accumulated bearing upon this 

question, and it has accumulated all upon one pan of the balance. Faunas 

in' a general way related to the Caney fauna prove to have had a wide dispersion on the North American continent and to have been confined to Mississippian time wherever the facts of paleontology and stratigraphy permitted this to 

be determined. On the other hand, or perhaps in other words, no fauna whose 

.age could be determined as Perinsylvanian has been found that is in any 

sense comparable to the fauna of the Caney shale. As a more -confined statement, many hundred collections of invertebrate fossils have been examined 

from areas in Oklahoma and Arkansas continuous with that in which the Caney 

:shale occurs. In these collections a profound faunal change is shown between 

those that came from the Morrow group, which is of Pennsylvanian (Pottsville) 

age, and those that came from the underlying Mississippian formations. Without exception, wherever faunas of the Mississippian type were obtained, they 

occurred stratigraphically below faunas of the Morrow type.

In this region, then, where the evidence is so pertinent and so abundant, 

its bearing is perfectly plain. The faunal succession is the same in the region 

where the Caney, Jackfork, and Stanley are developed. The higher fauna of 

the Caney shale is entirely different from the lower fauna and is closely 

related to that of the overlying Wapanucka limestone, the upper part of the
74 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Caney shale and the Wapanucka limestone being without much question of 

Pottsville age and belonging in the general horizon of the Morrow group.

If the Wapanucka and the upper part of the Caney correlate with the 

Morrow group, the lower part of the Caney occupies the same position in the 

geologic sequence as the Mississippian beds that underlie the Morrow. Not 

only so, but its fauna, as already pointed out, is rather closely related to the 

faunas of those Mississippian formations, whereas no rocks belonging to the 

Morrow, much less any of those that overlie the Morrow, have furnished 

anything even remotely comparable to it.

E. O. Ulrich presented at Tulsa, Okla., in March, 1927, a paper 

that was based on extensive field investigations by him in 1908 and 

previous years and also on recent office studies of fossils. In this 

paper, which was published in 1927 as Bulletin 45 of the Oklahoma 

Geological Survey, he expresses the opinion that the Stanley shale 

is of Mississippian age and that the Jackf ork sandstone and the overlying Caney shale (called by him the Johns Valley shale) are of 

Pennsylvanian age. He holds that the fauna in this shale is not in 

place, but has been transported from exposures of Mississippian Caney 

shale and that the fauna is now really embedded in a black shale of 

Pennsylvania age. After the presentation of Mr. Ulrich's paper Mr. 

Miser spent three months making a special field study of the age 

relations of the Carboniferous rocks in the Ouachita Mountains of 

Oklahoma. Among the things Mr. Miser did was to examine carefully the Caney shale at its type locality, which is now known as 

Johns Valley. This locality is also the type locality of the Johns 

Valley shale of Mr. Ulrich.

The shale in Johns Valley lies on top of the Jackf ork sandstone 

in a broad, long synclinal basin. In the lower -50 to 100 feet of the 

shale there are numerous ice-borne boulders and blocks of many 

kinds of rock, including limestone, flint, and sandstone. The limestone masses, which are more numerous than the other kinds, range 

in size from small particles an inch or less in diameter to blocks 

measuring 30 feet across, though Mr. Miser observed one block measuring 200 feet in length, another measuring 100 by 195 feet, and: 

a third about 50 by 369 feet. Fossils obtained from many of the 

masses have been studied by Mr. Ulrich, who concludes that the 

faunas represented range in age from that of the Arbuckle limestone (Lower Ordovician part) to that of the Sycamore limestone 

(Kinderhook).

The boulder bed just mentioned is overlain by a black platy hard! 

shale perhaps several hundred feet in thickness. In several fresh,, 

clean exposures of the shale there are hundreds of small phosphate 

nodules most of them nearly spherical and many concretionary 

masses of limestone. The limestone concretions all lie parallel with 

the bedding of the shale, and the phosphate nodules are rather uniformly disseminated through portions of the shale. The nodules and!
STRATIGRAPHY 75

the limestone concretions contain fossils, all of which belong to the 

fauna of the Mississippian Caney shale. Every feature of the shale 

as revealed in the exposures can be matched with exposures of the 

Caney shale in the areas where it rests upon the Woodford chert 

The lithology of the shales in the two different stratigraphic positions one on the Jackfork and the other on the Woodford is the 

same. The character and arrangement of the limestone concretions 

are the same, and also the character and distribution of the phosphate 

marbles are the same. To Mr. Miser, as well as to several other 

geologists who accompanied him to Johns Valley in June, 1927, 

the conclusion which they reached while looking at the field relations 

was obvious that the fauna as represented in the phosphate nodules 

and limestone concretions lived, died, and was buried where it is now

found. If the fauna had been transported by floating ice, as is

believed by Mr. Ulrich, there would surely have been some admixture 

of the Caney fossils with those of pre-Caney age, and also there 

would surely have been an admixture of rocks of pre-Caney age. 

The excellent exposures of the Caney that were examined by Mr. 

Miser and his geologist companions do not reveal a single pre-Caney 

fossil nor a single specimen of rock of pre-Caney age.

The available evidence on the age of the Caney, Jackfork, Stanley, and Hot Springs formations is fully reviewed by C. W. Honess 

and Mr. Miser in Bulletin 44 of the Oklahoma Geological Survey, 

which was published in 1927. Their conclusions as expressed in that 

report are that the Caney shale of the Ouachita Mountains contains 

beds of both Pennsylvanian and Mississippian age, and that the Jackfork, Stanley, and Hot Springs formations are of Mississippian age.

JACKFOBK SANDSTONE

Definition, The Jackfork sandstone took its name from Jackfork 

Mountain, in the McAlester and Tuskahoma quadrangles, Oklahoma. As the name implies, the formation consists chiefly of sandstone, but it contains a little shale and millstone grit. It is underlain by the Stanley shale and overlain by the Atoka formation. In 

much of the southern part of the quadrangles herein described the 

truncated edges of these three formations, which dip at high angles, 

are covered by nearly flat-lying strata of Cretaceous age. The 

Jackfork is of Carboniferous age and, like the Stanley shale below 

it, is believed to represent a part of the Mississippian series. In 

the Caddo Gap quadrangle it ranges in thickness from about 5,000 

to 6,600 feet; in the De Queen quadrangle not all of the formation 

is exposed.

Distribution. In the Caddo Gap quadrangle the Jackfork sandstone occurs in six belts having a general south of west trend and
76 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

from half a mile to 3 miles wide on the Athens Plateau and in one 

small belt a few miles northeast of Glenwood, and in the De Queen 

quadrangle it occupies three belts with a like trend and range of 

width along the southern border of the Athens Plateau. In these 

belts the formation produces low ridges, rising but little above those 

in the areas of the Stanley shale and Atoka formation, but farther 

north, outside the quadrangles, it forms many of the highest ridges 

of the Ouachita Mountains.

The formation is best exposed along the streams. Although it is 

fairly conspicuous in the areas away from the streams in places 

standing in vertical ledges that resemble gigantic masonry the 

amount of sandstone that is exposed is small in comparison with the 

enormous thickness and areal extent of the formation. In those 

areas it is largely concealed by sand that has been derived from it by 

weathering, and a person may travel over it for considerable distances without seeing any exposures of sandstone.

Cha/roicter. Although the formation consists almost entirely of 

sandstone, there are some beds of green, finely fissile clay shale. The 

shale in the upper part aggregates on Little Missouri Kiver possibly 

400 feet, and that in the lower part in the same locality comprises 

two or three beds from 6 to 10 feet thick, but it constitutes a larger 

portion of the formation in probably most other parts of the 

quadrangles.

The sandstone is in beds, most of which are from 6 inches to 10 

feet thick, but many are much thicker, the thickest observed bed 

measuring 84 feet.

The sandstone is compact and ranges from fine to coarse grained; 

most of it is quartzitic. On talus slopes it occurs in hard, angular

blocks, and when long exposed forms rounded gray boulders, some 

of which weather by exfoliation. The prevailing and characteristic 

color of the unweathered sandstone is light gray, though some is 

bluish gray, greenish gray, or even white, and the color of weathered 

portions is light gray, yellow, or brown, the gray color being the 

most common. Altered feldspar grains' occur in much of the formation, and mica flakes are common, especially in the greenish beds. 

Other minerals which have been observed in thin sections are zircon, 

tourmaline, titanite, chlorite, pyrite, and magnetite.

Some of the sandstone, especially in the basal part, contains large 

quantities of rounded pebbles of milky quartz, which are usually 

the size of peas or smaller. Such sandstone, which is really a millstone grit, closely resembles that at the base of the Winslow formation in the Boston Mountains of Arkansas and Oklahoma. The 

beds containing this grit are more resistant to weathering agencies 

than the other beds, and when the Cretaceous sea formerly occupied 

the southern part of the quadrangles they withstood the attack of the
STRATIGRAPHY 77

waves, and in places in the Caddo Gap quadrangle formed low islands 

and promontories along the shore of that sea. Residual quartz pebbles 

from the basal part are abundant on the first ridge of Jackfork 

sandstone south of Glenwood, and some of them reach half an inch 

in diameter.

The sandy soil from fhe Jackfork sandstone is very poor. Few 

farms have been made on it, and most of those have been soon abandoned. The prevailing timber of the Jackfork is yellow pine, and 

that of the Stanley shale is pine mixed with hardwood trees. This 

fact is of great assistance in tracing the contact between the two 

formations.

Stratigraphic relations and age. The stratigraphic relations and 

age of the Jackfork sandstone are fully discussed in connection with 

the Stanley shale.

PENNSYLVANIAN SERIES 

ATOKA FORMATION

Definition. The Atoka formation received its name from Atoka, 

Okla. It consists of shale and sandstone and is considered to be of 

early Pennsylvanian (Pottsville) age. Not all the formation is present in the quadrangles, the upper. part having been removed by 

erosion, but the remaining part is fully 6,000 feet thick.

Distribution. In the Caddo Gap quadrangle the Atoka formation 

crops out in two east-west belts in the southern part of the Athens 

Plateau. One of these belts is less than half a mile and the other 

somewhat more than 2 miles wide. The formation ,is not exposed in 

the De Queen quadrangle and if present there is concealed beneath 

Cretaceous sediments along the southern border.

Charact&r. The sandstone and shale in the formation occur in 

nearly equal amounts. In some parts the formation is all sandstone 

through a thickness of 75 to 100 feet, but more commonly the shale 

and sandstone are about equally interbedded. The sandstone is 

hard, micaceous, ripple marked, and light to greenish gray, contains 

quartz grains of medium size, and occurs in beds from a few inches 

to 12 feet thick. In some beds near the base it is coarse grained and 

contains a small quantity of grit. The usual color of the exposed 

sandstone is brown. This color, together with ,the large content of 

shale, makes the formation easily distinguishable from the Jackfork 

sandstone. Most of the sandstone after weathering is readily eroded, 

so that ,the formation generally forms valleys between the ridges of 

Jackfork sandstone, though some beds of it stand up in rather 

prominent ridges.

Small quantities of asphalt are found here and there in the sandstone, and fragments of plants and fossil wood are. common. In
78

an abandoned railroad cut, known as Dead Man's Cut, on the west 

bank of Antoine Creek, east of the Caddo Gap quadrangle, 2 feet of 

the formation bears thin veins of carbonaceous material that resembles coal. Similar veins are reported from o.ther places but were not 

observed in the course of field work.

The shale is sandy and micaceous and is dark to coal-black, but 

weathers to a rusty color, then turns darker, and next becomes peagreen before finally changing to a red plastic clay. It differs from 

the shale of the formations beneath in being exposed in fewer 

places, in having a more basic appearance, and in breaking down 

into small splinters and granular fragments instead of flakes.

Black compact chert in a layer reaching a thickness of several 

inches was observed in the formation at a few places.

Stratigraphic relations and age. In the Caddo Gap quadrangle 

and to the north and east of it in Arkansas and also in parts of 

Oklahoma the Atoka formation rests upon the Jackfork sandstone, 

but in other parts of Oklahoma it rests upon the Wapanucka 

limestone, of Pennsylvanian age, and in still others, where this limestone is wanting, upon the underlying Caney shale, of ear]y Pennsylvanian and late Mississippian age. The Caney shale in turn 

rests upon the Jackfork sandstone in most of the Ouachita area of 

Oklahoma, but in parts of the Arbuckle area it succeeds the Sycamore limestone, of Mississippian age, and in others the Woodford 

chert classified by the United States Geological Survey as of Devonian (?) age, with which the middle and upper divisions of the 

Arkansas novaculite are herein correlated. Although the Caney 

shale and Wapanucka limestone have not been recognized in Arkansas, no unconformity has been detected in that State between the 

Jackfork sandstone and the Atoka formation. Whether an unconformity exists or whether the Caney and Wapanucka are only apparently absent and are represented in the upper part of the Jackfork 

or the lower part of the Atoka, or both, is not known; but the lithologic character of the upper part of the Jackfork is such as to lead 

to the conclusion that it does not represent either of the formations 

named. The lower part of the Atoka may possibly represent one or 

both of them, with such a difference in lithologic character as might 

come about in widely separated parts of the same formation.

The Atoka formation is overlain by the Hartshorne sandstone in 

the Arkansas Valley of Oklahoma and Arkansas, north of the Caddo 

Gap and De Queen quadrangles, and the Hartshorne is in turn 

overlain by the McAlester shale.

The Wapanucka limestone, which underlies the Atoka formation 

in parts of Oklahoma, is probably the equivalent, in part at least, 

of the Morrow group of the Boston Mountains in northern Arkansas
STRATIGRAPHY 79

and northeastern Oklahoma.54 The Atoka, Hartshorne, and McAlester formations are all the equivalent of the Winslow formation 

of the Muskogee and Tahlequah quadrangles 54 situated partly in 

those mountains, but only the first two and the base of the McAlester 

.are the equivalent of the Winslow as mapped in the Winslow quadrangle, and probably only the Atoka is the equivalent of the basal 

uneroded portion of the Winslow capping the mountains in the 

Payetteville, Eureka Springs, and Harrison quadrangles. The 

Winslow, which overlies the Morrow group (known by its flora to 

be of Pottsville age), has not yielded fossils for accurate correlation, 

though its partial equivalent, the Atoka formation, on the south has 

yielded a few collections of invertebrate fossils.55 Mather, in commenting on one of the collections, says the deposition of the Atoka 

sediments must have begun in early Pottsville time.

The McAlester formation is known from its flora to correspond 

in age to the lower portion of the Allegheny formation in the 

Appalachian trough.56

Concerning the flora associated with the Coal Hill coal, which lies 

in the rocks immediately above the Hartshorne sandstone and at 

the base of the McAlester shale and which is commonly called the 

Hartshorne coal, David White 58 states that it indicates basal Allegheny age but contains a few traces of Pottsville development, 

illustrated particularly in Marioptems and Neuropteris. It thus 

:seems probable that the Atoka formation, which reaches an estimated

 thickness of 7,000 to 8,000 feet in the Arkansas Valley in Arkansas,

 6,000 to 7,000 feet in this valley in Oklahoma, and 6.000 feet in the

 Caddo Gap quadrangle, and the part of the Winslow lying below 

the horizon of the Hartshorne sandstone are of Pottsville age, and 

they are so classified by White.

CRETACEOUS SYSTEM

COMANCHE SERIES (LOWER CRETACEOUS) 

TRINITY FORMATION

Definition. The Trinity formation was so named because of its

 extensive development around the headwaters of Trinity River in 

Texas, whence its outcrop extends as a continuous belt northward

M Taff, J. A., U. S. Geol. Survey Geol. Atlas, Tahlequah folio (No. 122), 1905; Muskogee 

folio (No. 132), 1906.

65 Mather, K. P., Pottsville Formations and Faunas of Arkansas and Oklahoma: Am. 

Jour. Sci., 4th ser., vol. 43, p. 137, 1917.

Morgan, Q. D., Geology of the Stonewall Quadrangle, Oklahoma: Bur. Geology Bull. 2, 

pp. 64-65, Norman, Okla., 1924.

M White, David, Report on Fossil Plants from the Coal Measures of Arkansas: U. S.

 Geol. Survey Bull. 326, pp. 24-31, 1907.
80

into southern Oklahoma, and thence eastward into southwestern. 

Arkansas. In the quadrangles her'ein described it consists of clay,, 

sand, gravel, limestone, gypsum, and celestite, the most abundant 

named first and the least abundant last. The limestone occurs in. 

two beds, the Dierks limestone lentil, the older, near the base, and 

the De Queen limestone member, the younger, near the middle of theformation. The first was named from Dierks, in the De Queen 

quadrangle, near which it is exposed, and the second was named 

from De Queen, where it is exposed. The gravel also occurs as two 

beds, the Pike gravel member at the base, and the Ultima Thulegravel lentil, which is above the Dierks limestone. The Pike gravel 

was named from the village of Pike, in the Caddo Gap quadrangle,, 

and the Ultima Thule gravel was named from the village of Ultima 

Thule, in the De Queen quadrangle. These four lentils and members and the interbedded sand and clay of the Trinity dip about. 

100 feet to the mile toward the south. Although the Trinity lies 

nearly horizontal, it rests upon the truncated upturned edges of 

steeply dipping shale and sandstone of Carboniferous age, which 

however, form a floor that has only minor irregularities and undulations. A pronounced unconformity, therefore, occurs at the base of 

the Trinity. A notable though less striking unconformity exists 

at the top of the formation, as shown by the eastward truncation of 

its beds, and the resulting overlap of the Woodbine formation and 

the overlying Tokio formation, both of Upper Cretaceous age.

Distribution and thickness. The Trinity formation is exposed in 

a belt which trends eastward along the southern boundary of the De 

Queen and Caddo Gap quadrangles and hence lies within the northern border of the Gulf Coastal Plain. This belt has irregular north

and south boundaries, is narrowest on the east, and is continuous except where the formation is concealed by surficial deposits of alluvium and terrace remnants along the streams that cross the belt.

The formation ranges in thickness from about TO feet at the east 

line of the Caddo Gap quadrangle to more than 600 feet farther 

west. This maximum is indicated by a well 2 miles north of Center 

Point, Avhich entered the formation 100 feet or more below its top 

and which reached a depth of 500 feet without striking Carboniferous 

rocks. Its thickness at Nashville, Ark., about 3 miles south of theCaddo Gap quadrangle, where a well passed through it, is about 750- 

feet. The approximate depth to the base of the Trinity at any locality within the De Queen and Caddo Gap quadrangles may be obtained by multiplying the number of miles from the locality to the 

north boundary of the Trinity by 100, the approximate average 

southward dip in feet per mile of the base or floor of the Trinity, 

To make this calculation as accurate as possible the difference in altitude of the locality above or below that of the Trinity boundary due
STRATIGRAPHY 81

north of the locality should, as the case demands, be added to or subtracted from the figure obtained by the above method. The altitude 

of the base of the Trinity in the southern parts of the quadrangle is 

shown by contours in Figures 8 and 9. (See pp. 184-185.)

Owing to the southward dip of the formation its younger bed^ 

are exposed south of the older ones.

Character. The Pike gravel member is the thickest and most persistent gravel bed in the quadrangles and has a larger surface distribution .than any other. In much of its belt of outcrop it forms 

an even though dissected south ward-dipping upland. This form is 

due to the resistant nature of the gravel and the ease with which the 

overlying unconsolidated clay and sand have been eroded. Some of 

the larger areas of outcrop are at or near Pike, Nathan, Muddy Fork,

Dierks, Lebanon, and King. The thickness of the gravel is rather

uniform, being in most places between 20 and 50 feet, but it apparently attains 100 feet near Pike. The gravel thins out at a few isolated places within its belt, as near Murfreesboro and Lebanon, where 

rocky headlands and islands of Carboniferous sandstone along the 

old Cretaceous shore were not completely buried by the gravel, 

though they were by higher beds. The sand and clay separating the 

Ultima Thule and Pike gravels thin to the west and are absent just 

west of the Arkansas-Oklahoma line, in consequence of which the 

"Ultima Thule gravel either rests upon the Pike gravel or upon Carboniferous rocks. If the Pike gravel is present there it can not be 

distinguished from the overlying gravel.

This gravel consists mainly of pebbles less than half an inch in 

diameter, but it contains many larger ones and some cobbles as much 

as 10 inches in diameter. These larger pebbles and cobbles are at 

most places especially abundant in a thickness of several feet at 

the base. All the pebbles and cobbles are partly to thoroughly 

rounded. Most of them are dense white, gray, brown, red, or black 

novaculite, unquestionably derived from the Arkansas novaculite, 

which is exposed in the Ouachita Mountains. A small number, however, are quartz, quartzite, and sandstone. Those of quartzite and 

sandstone are most abundant in the cobble bed, but they constitute 

a minor portion, of it. The proportion of quartz pebbles in the Pike 

gravel and the Ultima Thule gravel increases westward from the 

longitude of De Queen. They are derived from quartz veins in 

McCurtain County, Okla., which are largest and most numerous in 

the Ordovician shale in the central part of the county. The proportion of pebbles derived from the novaculite in that county likewise increases westward from the longitude of De Queen. Some of 

the gravel is conspicuously cross-bedded. Most of it is loose and 

contains some sand or clay as lenses in the upper part and as a
82 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

filling in the interstices between the pebbles. Nearly horizontal beds 

of gravel are in places cemented.by brown iron oxide and are thus 

converted into hard conglomerate. The source of the iron oxide 

was probably iron pyrites, which was once disseminated through the 

gravel and adjacent beds and was later taken into solution by ground 

water and deposited in its present form at or near the surface. Much 

of the gravel in the vicinity of Nathan is firmly cemented with a 

small percentage of silica. Three exposures of gravel thus cemented 

were observed along the wagon road leading south of east from 

Nathan to Murfreesboro; the one farthest east is at the ford across 

Bacon Creek, 2% miles from Nathan. The best exposed section of 

the Pike gravel in the quadrangles is at Bluff Ford, 1 mile west of 

Nathan. (See pi. 9, B.)

The Ultima Thule gravel lentil is exposed in a discontinuous 

crooked belt extending from a point near Ultima Thule eastward as 

far as Cossatot River, beyond which it is represented here and there 

by lenses a few feet thick. The lentil itself is only a few feet thick 

just west of the Cossatot and is not far above the Dierks limestone 

and about 100 feet above the Pike gravel. It thickens toward the 

west and reaches a maximum of 40 feet near the State line. Just 

west of the State line it rests upon the Pike gravel or upon Carboniferous rocks. It resembles the Pike gravel except that most of the 

pebbles are smaller, only a few exceeding 1 inch in diameter.

Lenses of gravel as much as 25 feet thick occur above the De 

Q.ueen limestone northwest of Provo. They resemble the two gravel 

beds just described.' . . .

In addition to the bedded deposits much gravel occurs scattered 

over the surface as residual material from the erosion of beds that

now crop out and of others that have entirely disappeared.

The beds of gravel of the Trinity formation, as well as the later 

beds .of gravel in the quadrangles, have been held by some geologists 

to be surficial deposits of post-Tertiary age. The opinions of the 

different geologists have been diverse, however, and are briefly given 

on pages 97-99.

The Dierks limestone lentil is exposed in an irregular belt extending from the vicinity of Delight westward to Cossatot River. It is 

cut out on the east, owing to an overlap of the Woodbine formation 

upon lower beds of the Trinity; on the west it thins out and seems 

to give way. horizontally to clay which occupies a part of the interval 

between the Pike and Ultima Thule gravels. The westernmost outcrop that was observed is just northwest of Moody Shoal Ford. The 

limestone lies about 50 feet above the base of the Trinity formation 

along the western part of .its outcrop and probably 200 feet above 

the base north ,of Delight.,.; Northwest, of .Murfreesboro it. laps up 

against rocky headlands of Carboniferous sandstone which jutted out
STRATIGRAPHY 83

into the old Cretaceous sea. The lentil approximates 40 feet in thickness at most places but at some is only 10 feet thick. It is composed 

of alternating beds of limestone and green clay, but the limestone 

usually predominates. Much of the limestone is compact, gray, and 

hard and occurs in even-bedded layers attaining the thickness of one 

foot, but a considerable portion is earthy and shaly. The limestone 

weathers to thin slabs and nodular masses and usually produces a 

black soil, which gives the belt of country underlain by this limestone 

the popular name " black-land belt."

The De Queen limestone member is exposed in a narrow, somewhat 

sinuous band which extends north of west and west from Plaster 

Bluff, 3 miles south-south west of Murfreesboro, passing north of 

Corinth and Center Point, and thence passing through De Queen and 

into Oklahoma. The member is about 60 feet thick at most places 

but is a little more than 70 feet thick along Messer Creek and 72 feet 

thick at De Queen. It consists of limestone with an equal or greater 

quantity of tough green clay and some gypsum and celestite. Most 

of the limestone is gray, hard, and compact and is in layers 10 inches 

or less thick; but much of it is earthy, platy, and yellowish gray and 

contains small lenses of clay. Ripple marks, sun cracks, and worm 

trails are found on the surface of some layers, and disseminated 

crystals of pyrite are common. The gypsum occurs in the lower part 

of the member. The thickest exposure is in Plaster Bluff, where the 

gypsum is found in a single bed ranging from 10 to 14 feet in thickness. This bed consists of pure saccharoidal gypsum, though there 

are some thin seams of satin spar and as much as 3 feet of interbedded 

clay in its lower part. The thickest layer of gypsum is at the top 

and is four feet thick. There are a few outcrops and reported occurrences of gypsum as far west as Messer Creek, but there it is not 

everywhere pure and at no place does its reported or observed thickness exceed three feet. Coarsely granular white to pink celestite 

qccurs in clay in the lower part of the member, in some places as 

short lenses and in others as a single layer from 1 to 6 inches thick. 

The thicker layers and lenses contain vugs which are lined with large 

tabular crystals. Only a few exposures of this mineral have been 

observed, the westernmost one near Provo and the easternmost at 

Plaster Bluff. The most extensive exposures are near Martha post office, where the mineral occurs on the surface as friable residual masses.

The De Queen member usually forms a poor yellowish-brown clay 

soil. Throughout much of its belt of outcrop ledges and boulders are 

found at the surface, but in places the limestone is entirely concealed 

by surface material; in some such places its presence may be detected 

from the growth of hawthorn thickets over it.

Clay occurs in all parts of the Trinity formation, but constitutes a 

greater proportion of the middle thajn of the lower and upper parts.
84 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

It is interbedded with sand, gravel, and limestone, and in places contains sand, pyrite, novaculite pebbles, lenses of impure limestone, 

pieces of carbonized fossil wood, and pot-shaped concretions of iron 

oxide. The fresh clay is white, blue, green, purple, or red, and all 

these colors may be seen in different layers in a single exposure.

Sand occurs mostly in two beds. The lower lies between the Pike 

gravel and the Dierks limestone. It is thickest on the east and thinnest on the west, and at a few localities near Pike, Delight, Murf reesboro, and Lebanon it is impregnated with asphalt. The higher sand 

is at the top of the formation and does not extend east of the longitude of Center Point, beyond which it is overlapped by the Woodbine formation. The sand is cross-bedded and fine grained, is interbedded with some clay, and is usually compact, but a small quantity 

is firmly cemented by iron oxide. It is gray where unweathered, but 

is red or yellow in most exposures, and it produces a gray soil.

A number of deep wells have been drilled in the Trinity formation 

in the quadrangles, most of them at and near De Queen. The log of 

one of them is given below to show the character of the Trinity in 

that vicinity.

Log of ice-factory well near the Kansas City Southern Rwllway station at

De Queen

[Altitude of top of well about 375 feet above sea level. Depth of well as given in the log is 244 feet; the actual

depth is 249 feet]

Quaternary system (stream deposits):

Cretaceous system (Trinity formation): 

De Queen limestone memberLimestone. _ . ____________________________

Blue clay.. ____________________________________

Yellow clay ________________ ... ___________________

Dierks limestone lentilBlue clay. - ____________________ . __________________

Pike gravel member: Gravel; base not reached _______ ..: _ . _________

Thickness

Feet 

12

6

4

8

7?

9?

3

11

7

14

9

18

5?

7

30

10

7

12

4

9

10

12

7

23

Depth

Feet 

12

18

22

30

37

46

49

60

67

81

90

108

113?

120

150

160

167

179

183

192

202

214

221

244

A recent report by Honess 57 describes occurrences of " fine yellow 

sand with locally a little small gravel showing " on the higher ridges

67 Honess, C. W., Geology of the Southern Ouachita Mountains of Oklahoma: Oklahoma 

Geol. Survey Bull. 32, 1923.
STRATIGRAPHY 85

west of Blanchard post office in the De Queen quadrangle. He 

expressed the opinion in the report that the deposits are Cretaceous; 

but at the end of a visit to the localities in October, 1923, in company 

with Mr. Miser, he and also Mr. Miser concluded that most if not all 

the material there is deep residual sand from the underlying thick 

beds of sandstone in the Stanley shale.

Fossils and correlation. Invertebrate fossils in the Trinity formation occur only in. the Dierks limestone lentil and the De Queen 

limestone member, and they represent a brackish-water molluscan 

fauna with some purely marine elements. There is, however, a small 

quantity of carbonized wood in different parts of the formation and 

some vertebrate fossils, a few of which have been found in beds not 

far below the De Queen limestone, at the base of Plaster Bluff. 

Concerning the vertebrate fossils K. T. Hill 58 says that they " have 

the appearance of being saurian remains, except what is probably the 

palatal bone of a fish, resembling the Lepidotus mantelli Agassiz." 

The Dierks limestone contains great numbers of small oysters (Ostrea 

franklini) and other shells, most of which are more or less comminuted. The oyster shells are more numerous than the others and 

in places make up beds several feet thick. The De Queen limestone 

is less fossiliferous than the Dierks, but fossils consisting mainly of 

Ostrea franklini and other pelecypods are numerous in many layers.

T. W. Stanton, to whom the fossils collected from these limestones were transmitted for identification, states that they belong 

to the fauna of the Trinity group of Texas and show a rather definite relationship to the fauna of the Glen Rose limestone of that 

State.

A collection from the Dierks limestone in the northeast corner of 

sec. 3, T. 8 S., R. 27 W., 3 miles west-southwest of Nathan, contains 

the following species:

Ostrea franklini Coquand. 

Anomia texana Hill. 

Modiola branneri Hill. 

Astarte? sp. 

Glauconia sp.

Another collection from this limestone in the northeast corner of 

sec. 9, T. 8 S., R. 25 W., about 2 miles northeast of Murfreesboro 

contains the following species:

Serpula paluxiensis Hill. 

Ostrea franklini Coquand. 

Exogyra sp. 

Anomia texana Hill.

68 Hill, R. T., The Neozoic Geology of Southwestern Arkansas: Arkansas Geol. Survey 

Ann. Kept, for 1888, vol. 2, p. 152, 1888.

6242 29 7
86 £>E QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Modiola branneri Hill?

Nucula sp.

Barbatia parva missouriensis Hill?

Cucullaea sp.

Eriphyla pikensis Hill.

Astarte sp.

Corbicula arkansaensis Hill.

Cardium? sevierense Hill.

Specimens of ammonites and of Nautilus have been collected by 

T. W. Stanton in the Dierks limestone near Murfreesboro.

The combined faunas of three collections made from the De Queen 

limestone between Fairview Church and Cossatot River, a few miles 

east of De Queen, contain the following species:

Serpula paluxiensis Hill.

Membranipora sp.

Ostrea franklini Coquand.

Anomia texana Hill.

Barbatia parva missouriensis Hill?

Mytilus tenuitesta Roerner?

Astarte? sp.

Avicula sp.

Eriphyla pikensis Hill.

Cyprina? sp.

Glaucoma branneri Hill.

Glauconia? sp.

Many specimens of Ostrea franklini var. camelina Cragin, a much 

larger species than Ostrea franklini, were found near the base of the 

De Queen limestone by the roadside, 2 miles north of Provo.

GULF SERIES (UPPER CRETACEOUS) 

WOODBINE FORMATION

Definition. The Woodbine formation of the Gulf series (Upper 

Cretaceous) received its name from the village of Woodbine, in 

Cooke County, Tex. The formation consists mainly of quartz sand 

in northeastern Texas and in Bryan and Choctaw Counties, Okla.,. 

where it is appropriately called the Woodbine sand. Water-laid 

volcanic material is present in the Woodbine but increases in 

quantity toward the east in Texas, Oklahoma, and Arkansas and 

makes up a large part of the formation in McCurtain County, Okla.. 

and in southwestern Arkansas, where the term formation is more 

suitable than the term sand. In Arkansas the Woodbine comprises 

the lower part of the "Bingen sand" of Veatch and later authors.

Distribution and character. The area of outcrop of the Woodbineformation is a belt extending from the valley of Little Missouri 

River near Murfreesboro, in the Caddo Gap quadrangle, in a west 

by south direction across this quadrangle and the southeast corner
STRATIGRAPHY 87

of the De Queen quadrangle. The Woodbine and also the gravel 

and sand of the younger Tokio formation produce the southwardsloping Lockesburg cuesta on which the villages of Centerpoint, 

Corinth, and Highland are located. A description of the cuesta is 

given on pages 17-18.

The thickness of the formation in the Caddo Gap quadrangle 13 

not definitely known but appears to be as much as 200 feet. It thins 

eastward and is not present east of the valley of Little Missouri 

River in this quadrangle. The thickness of the formation as revealed 

in a well at Nashville, 4 miles south of the Caddo Gap quadrangle, 

is apparently 350 feet. Only the lower part of the formation the 

basal gravel, some 60 feet thick is present in the De Queen quadrangle. The beds above this gravel crop out farther south.

Besides the gravel at the base of the formation there are thinner

beds and lenses of gravel that occur here and there in water-laid volcanic tuff that overlies the basal gravel. These several gravel deposits 

resemble one another as well as those of the Trinity formation. Like 

the gravel beds in the Trinity and in the terrace deposits, they have 

all been held by some geologists to be of post-Tertiary age. This and 

other views concerning the gravel beds are briefly discussed on 

pages 97-99.

The gravel deposits in the Woodbine formation are cross-bedded 

and are composed of partly rounded to well-rounded pebbles, most of 

which are less than 1 inch in diameter, although many reach a diameter of 6 inches. Some beds 12 to 15 feet thick, as well as thinner ones, 

have been converted into hard conglomerate by the infiltration of 

iron oxide, which has cemented the pebbles together. Most of the 

pebbles are novaculite; the rest are quartz, quartzite, and sandstone. 

The novaculite pebbles are commonly white, but various shades of 

red, blue, gray, green, brown, and yellow are common. It is obvious 

from the nature of these pebbles that they were derived from the 

rocks of the Ouachita Mountain region, but many doubtless came 

directly from partly eroded gravel beds of the Trinity.

In addition to the kinds of pebbles just mentioned there are rather 

extensive deposits of pebbles of igneous rocks. Most of the larger 

igneous pebbles that have been observed do not occur in the thicker 

beds of gravel but in thin beds and lenses of gravel interbedded in 

the volcanic tuff, though numerous small pebbles are disseminated 

through the tuff.

Clay is found at some places in beds many feet thick interbedded 

with the volcanic tuff. It is gray to brown, is laminated, and contains at places fossil leaves, some of which were collected at a locality 

on Mine Creek, 4 miles north of Nashville, Ark., half a mile south of 

the southern border of the Caddo Gap quadrangle.
88 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

The volcanic tuff in the Woodbine occurs in widespread beds that 

attain a thickness of 125 feet or more. The tuff is mostly crossbedded, soft, grayish and olive-gray, is composed of coarse and fine 

grains of volcanic rocks and is for the most part unconsolidated but 

is in a few places cemented by calcite. The calcite-cemented masses 

are lenticular and spherical. The best exposures of tuff in the Caddo 

Gap quadrangle are on and near Mine Creek, Blue Bayou, and other 

streams near Centerpoint.

The tuff deposits vary greatly in texture and in mineral composition, and the various materials are commonly more or less mixed, but 

two main types of pyroclastic deposits can usually be recognized. 

One may be called a lithic tuff 59 that is, one composed predominantly of fragments of rocks that were originaly crystalline, or almost 

completely crystalline. The second is vitric tuff,59 composed largely 

of glassy pumice, or more commonly of alteration products derived 

from glassy volcanic fragments. Both types contain variable 

amounts of crystal grains that represent phenocryts set free from 

their matrix by the explosive eruptions that pulverized and scattered 

the rock. They also contain more or less water-laid debris derived 

from pre-Upper Cretaceous sedimentary rocks.

The unweathered lithic tuff is greenish gray and is formed of 

rather well-sized rock pellets and mineral fragments, commonly 2 

to 4 millimeters in diameter. The rock grains are rounded to subrounded, and the mineral grains are euhedral or angular and are usually without signs of attrition. These crystal grains are orthoclase, 

pale-green augite, brown hornblende, black spinel, magnetite, titanite, 

and apatite. The orthoclase and augite are most abundant. The

augite is commonly euhedral with very delicate multiple-terminating 

pyramids that give a cockscomb-like habit. The titanite, spinel, 

and magnetite have very perfect euhedral crystal faces. Some of the 

small rock fragments came from an older tuff bed of a type that was 

clearly deposited directly from the air, and such fragments have been 

reworked.

The lithic tuff was produced in large measure by the explosive 

pulverization of material that had previously crystallized in the throat 

of a volcano, or it was produced by an eruption breaking through 

previously formed igneous rock masses. However, the presence of 

euhedral crystals indicates that molten material contributed to the 

lithic tuff. Such crystals must have been set free from a liquid or 

pasty matrix before they were blown into the air. The shattering 

of a solid rock mass would give only crystal fragments.

The vitric tuff is light colored, being blue-gray or cream-colored to 

almost white. The most abundant phenocrysts are angular or euhe-

» Krsson, L. V.. Am. Jour. Sci., 4th: ser., vol. 40, p. 193, 1915.
STRATIGRAPHY 89

dral orthoclase. Dark minerals occur in smaller quanitity than in the 

lithic tuff and are entirely absent at some horizons. Where present 

they include biotite, augite, hornblende, titanite, apatite, and magnetite. The pumice fragments, which reach a maximum diameter of 

an inch or more, usually have elongated bubble walls, giving a 

fibrous structure which closely resembles that of rotten wood. Some 

of the fragments have very thin bubble walls and a structure so 

delicate that they go to pieces at a touch.

The rock types represented in the two varieties of volcanic material, 

do not differ greatly and are similar to the fresh igneous rock pebbles and cobbles that are sparingly found in the gravel beds and 

lenses associated with the tuff. The predominant rock type is dark 

gray or dark greenish gray, with few phenocrysts reaching a maximum diameter of 5 millimeters and usually a very fine grained

groundmass. The microscope shows a trachytic structure characterized by rudely parallel plagioclase crystals, 0.1 millimeter in length 

in the coarser types and 0.02 in the finer-grained ones. The mineral 

composition is about as follows:

Mode of the predominant volcanic rock in the Woodbine formation

Plagioclase______________________________ 50-65 

Orthoclase______________________________ 20-40 

Nephelite_______________________________ 15-20 

Pyroxene or hornblende____ ____ _ ______ 2-15

The rocks are porphyritic, orthoclase and augite or hornblende 

phenocrysts forming 1 or 2 per cent of the rock. Plagioclase with a 

composition near oligoclase is the most abundant mineral and occurs 

in very slender prisms which give the rocks a trachytic structure. 

Orthoclase occurs as rare phenocrysts and as groundmass material 

less abundant than plagioclase. ISTephelite occurs in very small euhedral crystals inclosed in feldspar and also as interstitial material 

between feldspar grains. Pyroxene is rare, and instead of it brown 

hornblende is found in a few specimens. The predominant type 

of volcanic rock is best described as a phonolite. Other identified 

types include nephelite syenite, a haiiyne phonolite, and fourchite 

similar to but more feldspathic than that from the Hot Springs 

region.

The vitric tuff contains a large proportion of glass that is usually 

completely altered to clay minerals. For this reason the rock types 

represented by the glass can not be exactly determined. It is probable that in part they represent glassy phases of the phonolite. 

However, the larger proportions of orthoclase, the smaller proportions of ferromagnesian minerals, and the fact that the glassy material is commonly rather silicic indicate that the pumice tuffs are
90

derived largely from syenitic rocks. On Mine Creek occur tuff 

masses that are composed entirely of altered glass and orthoclase 

ivith no dark minerals whatever, and it is probable that these represent a normal syenite.

The deposits of tuff when fresh are greenish gray, bluish gray, 

and cream-colored to almost white, but on weathering they become 

a yellow, mealy earth that still retains the texture of the fresh rock, 

and that finally changes to red plastic clay at and near the surface. 

Comparatively unoxidized bentonitic tuff is found only in wells and 

a few exposures.

The volcanic material in the Woodbine formation in the Caddo 

Gap quadrangle and also in adjoining areas in Arkansas, Oklahoma, 

and Texas is fully described in Professional Paper 154-F, by C. S. 

Eoss, H. D. Miser, and L. W. Stephenson.

Age and stratigraphic relations. The Woodbine formation rests 

upon the truncated edges of different parts of the Trinity formation 

of the Comanche series in the De Queen and Caddo Gap quadrangles, 

the youngest subjacent beds being to the west and the oldest to the 

east. A marked angular unconformity therefore separates the Gulf 

series from the Comanche series. The table on page 94 shows the 

stratigraphic relations of the Woodbine in the De Queen and Caddo 

Gap quadrangles and also in southeastern Oklahoma and northeastern Texas.

The fossils and correlation of the Woodbine are discussed under 

the Tokio formation on pages 92-94.

TOKIO FORMATION

Definition. The' Tokio formation received its name from the

village of Tokio, at the southern edge of the Caddo Gap quadrangle. 

The formation when first defined by Miser and Purdue was described as the " Tokio sand member of the Bingen formation." 

Recent field work by Stephenson and Dane, in which Miser cooperated for short periods of time, has shown that an unconformity 

occurs at the base of a gravel bed immediately underneath the 

"Tokio sand member of the Bingen." It has also shown that the 

part of the " Bingen " below this gravel bed is equivalent to the 

Wodbine sand of Texas. As a result of this work, and also as a 

result of study of the fossils by Stephenson, the following changes 

in names have been made: (1) The name " Bingen " has been discontinued in Arkansas and Oklahoma; (2) the "lower Bingen" 

the part below the unconformity is called the Woodbine formation; 

(3) the "Tokio sand member of the Bingen" is now called the 

Tokio formation, though the lower limit of the new formation is 

extended so as to include the heavy gravel at whose base there is an
STEATIGEAPHY 91

unconformity. The Tokio formation as thus defined has a basal 

gravel like the Woodbine, and each formation has an unconformity 

at its base. The formation in the Caddo Gap quadrangle rests upon 

lower and lower rocks toward the east, first upon the truncated edge 

of the Woodbine formation, then upon successive parts of the Trinity 

formation.

Distribution and chwaoter. The Tokio formation is exposed in a 

belt which extends in a west by south direction across the Caddo 

Gap quadrangle and which passes south of the De Queen quadrangle. 

The belt of exposure is not continuous but is broken by bands of 

alluvium and terrace gravel along several streams that cross it. 

The formation appears to range from 100 to 150 feet in thickness. 

It is composed largely of sand and gravel with some clay. The 

gravel bed at the base is as much as 25 feet thick, but there are three 

other beds higher in the formation, the thickest of which is 50 feet 

thick. The gravel deposits are composed of well-rounded pebbles 

consisting of quartz and novaculite of many colors and ranging in 

size from that of a pea to a diameter of about 6 inches. Parts of 

some beds are cemented together with iron oxide and are thus hard 

conglomerate.

The exposures of sand and clay in the Caddo Gap quadrangle are 

mostly confined to the vicinity of Tokio and the region east of Little 

Missouri River. The sand is an incoherent though firmly packed 

gray quartz sand in beds, some of which are more than 30 feet 

thick. It is conspicuously cross-bedded, contains disseminated particles of kaolin and a few scattered pebbles, becomes red on weathering, and produces a gray sandy soil. Light and dark clays are 

interbedded with the sand. Some of them contain fossil plants, and 

some contain small quantities of pyrite and lignitiferous matter. 

The light-colored clays are in beds that reach a thickness of 5 to 6 

feet, and they consist of plastic ball clay and kaolin. The kaolin 

is chalky white to creamy in color, but the lowest layer of one bed 

has a lavender color. It is nonplastic, is very fine grained, and 

breaks with a conchoidal fracture. It has been prospected, and 

samples have been tested and found to be fuller's earth. Also many 

experiments have been made to determine its fitness in the manufacture of china ware, but thus far the bed has not been worked.

The kaolin is very pure clay and has little resemblance to the tuff 

of the Woodbine formation, but microscopic studies by C. S. Eoss 

apparently show that the beds were originally beds of volcanic dust. 

The largest dust fragments are less than 1 millimeter in diameter, 

and most of the individual fragments are so small that the original 

rock structure is evident only in the rock pellets of the coarse-grained 

parts of the beds. In the pellets the crystalline rock structure is
92 DE QUEEN" AND CADDO GAP QUADRANGLES, ARKANSAS

retained and shows that the rock was a phonolite. The heavy minerals, augite, hornblende, zircon, and tourmaline, are present in very 

small amount, but the rock contained little besides feldspar and 

nephelite.

The lower beds of the Tokio formation on the Kiley place and on 

the Twin Knobs, near Murfreesboro, consist in large part of altered 

serpentine grains and peridotite fragments. Although the beds are 

water-laid, showing lamination and pronounced cross-bedding, the 

igneous1 material may have been ejected into the air from the nearby vents at the diamond mines and then fallen to or near its present 

position. There is, however, no evidence known as yet against the 

derivation of the material from adjacent peridotite exposures by 

means of erosion.

Age and correlation. The Woodbine and Tokio formations have 

yielded fossils from which the age of the formations may be determined. Fossil plants have been obtained from the Woodbine formation on Mine Creek 4 miles north of Nashville, Ark., and <from the 

Tokio formation in the big railroad cut 2,y2 miles east of Tokio, Ark., 

and in the Adams kaolin pits in sec. 24, T. 8 S., R. 25 W., 5 miles eastsoutheast of Murfreesboro, Ark. The plants at the Adams pits 

occur in a 5-foot bed of kaolin which is probably altered volcanic 

material; the plants on Mine Creek are from a lens of clay in a 

thick bed of tuff; and the plants at the railroad cut are from a dark 

gumbo clay that is overlain by sand and light-colored clay.

No fossil invertebrates have been found in the Woodbine formation in Arkansas, but' the Tokio formation has yielded small collections,60 mostly of poorly preserved prints and molds from five or six 

localities south of the De Queen and Caddo Gap quadrangles.

The fossil plants from the Woodbine and Tokio formations have 

been studied by Berry,61 who has also studied a fossil flora of 43 

species from the Woodbine sand at Arthurs Bluff, on Red River in 

Lamar County, Tex.,62 where the fossil plants occur both associated 

with coarse sandstone containing a considerable percentage of tuffaceous material and in more or less sandy cross-bedded clay interbedded with and overlying the standstone. Berry says:

I can therefore only state the well-known fact that the Woodbine and Bin gen 

formations are at least partly contemporaneous. I am of the opinion, which 

is based on the range of the Woodbine plants in other formations, that Arthurs 

Bluff is approximately on the boundary between the lower and upper members 

of the Bingen as recognized by Miser in Arkansas in the specific area where 

he collected the plants.

80 The collections were made by C. H. Dane, L. W. Stephenson, and H. D. Miser.

61 Berry, B. W., Contributions to the Mesozoic Flora of the Atlantic Coastal Plain, XII 

Arkansas: Torrey Bot. Club Bull. 44, pp. 167-190, 1927.

82 Berry, E. W. The Flora of the Woodbine Sand at Arthurs Bluff, Tex.: U. S. Geol. 

Survey Prof., Paper 129, pp. 153-181,
STKATIGKAPHY 93

Since the publication of Berry's papers on the fossil floras of the 

Bingen formation of Arkansas and the Woodbine sand at Arthurs 

Bluff, in Texas, much has been learned in regard to the age and 

stratigraphic relations of these and other formations of the Gulf 

series in Arkansas and northeastern Texas. Miser and Purdue 63 in 

1919 divided the Bingen sand of Veatch, in Howard and Pike Counties, Ark., into the lower or main part of the formation and an upper 

or Tokio sand member. The distribution of the Tokio sand member, 

as represented on the map accompanying the paper cited, shows that 

it overlaps the main part of the Bingen and finally conceals completely the Bingen from west to east. The unconformity beneath 

the gravel bed at the base of the Tokio formation of the present 

report has since been traced by C. H. Dane to the southwest as far 

as Little Eiver, where it is concealed by the river alluvium. From

northeast to southwest the Tokio, according to Dane,6 * becomes interstratified with beds of clay of increasing thickness, until in Sevier 

County the clay predominates over the sand.

The lower part of the Bingen sand of Veatch contains the thickest 

beds of volcanic tuff already mentioned, and thin beds of volcanic 

material are present in the overlying Tokio formation. The beds of 

volcanic tuff of the lower part of the Bingen sand have been traced 

by Miser westward from Arkansas through McCurtain, Choctaw, 

and Bryan Counties, Okla., and by L. W. Stephenson through the 

northern parts of Eed Eiver, Lamar, and Fannin Counties, Tex. In 

all these areas the beds of volcanic material form a continuous and 

characteristic deposit connecting directly with the upper part of the 

Woodbine sand. The tuffaceous beds are interbedded with the fossil 

plant-bearing beds at Arthurs Bluff. In Lamar and Fannin Counties the volcanic tuffs have been identified by Stephenson beneath 

the Eagle Ford clay, showing that the lower part of the Bingen is in 

reality the eastward extension of the upper part of the Woodbine 

sand.

The Tokio in Arkansas has been found by Dane to contain fossils 

at several stratigraphic positions, the lowest within 70 feet of the 

base, which, according to Stephenson, indicate with reasonable certainty that this division is younger than the Eagle Ford clay. Inasmuch as the lower part of the Bingen that is, the Woodbine sand 

passes beneath the Eagle Ford in Texas, and the upper part of the 

Bingen that is, the Tokio formation is younger than the Eagle 

Ford, it follows, according to Stephenson, that the Eagle Ford is 

represented in Arkansas by the unconformity between the Woodbine

68 Miser, H. D., and Purdue, A. H., Gravel Deposits of the Caddo Gap and De Queen 

Quadrangles, Arkansas: U. S. Geol. Survey Bull. 690, pp. 22-24, 1918. 

M Dane, C. H., U. S. Geol. Survey Mem. for the Press, Sept. 10, 1926.
94 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

and Tokio. The stratigraphic relations of the Woodbine and Tokio 

formations are shown in the table below.

Stratigra-phic relations of Cretaceous rocks of the De Queen and Caddo Gap

quadrangles

Northeastern Texas

Brownstown marl.

Blossom sand.

Bonham clay.

Ector tongue of Austin chalk; 

basal part is sbaly clay and 

sand with "fish bed conglomerate" at base. Thins 

out toward northeast in 

Fannin County.

Eagle Ford clay. Thins out 

toward east in Lamar 

County.

Woodbine sand.

Washita group.

Fredericksburg group.

Trinity sand.

Southeastern Oklahoma

Brownstown marl. Present in McCurtain 

County but not exposed.

Tokio formation. Present in McCurtain 

County.

Not present.

Eagle Ford shale. 

Present only in 

Bryan County.

Woodbine sand in 

Bryan and Choctaw 

Counties.

Not present 

in McCurtain 

County.

Woodbine formation in McCurtain County.

\Vashita group. Thins toward east.

Qoodland limestone.

De Queen and Caddo Gap 

quadrangles

Brownstown marl 

(restricted).

Tokio formation.

Not present.

Not present.

Woodbine formation. Thins 

out toward east in Caddo 

Gap quadrangle.

Not present.

1 Not present.

Trinity sand. Thins toward west by o\7 erlap of younger beds of formation over 

older beds of beds of formation.

Trinity formation. Thins 

out toward east beyond 

east border of Caddo Gap 

quadrangle. The eastward thinning is due to 

unconformity at base of 

Woodbine and Tokio formations.

BROWNSTOWN MARL

The lower part, probably 100 feet or more, of the Brownstown

marl occupies about 5 square miles in the southeast corner of the 

Caddo Gap quadrangle. Veatch 6C who has studied the formation 

over a much larger area than the authors of this paper, describes it 

as follows:

The Brownstown formation, into which the Bingen sand gradually grades, is 

well developed in the southern part of Sevier County, Ark., about Brownstown. 

from which place it takes its name. It is a blue or gray calcareous clay containing many fossil oysters and is characterized by the presence of the large 

oyster Exogyra, ponderosu, whence it lias sometimes been called the Exogyra 

ponderosa marl. The soil derived from the formation, when not mixed with 

surficial deposits, is black and waxy, but the subsoil is yellow, and in most of 

its outcrops the bed is a yellow clay marl.

A collection of fossils from the Brownstown marl was obtained by 

R. D. Mesler at an exposure along a wagon road half a mile southeast

96 Veatch, A. C., Geology and Underground Water Resources of Northern Louisiana and 

Southern Arkansas: U. S. Geol. Surrey Prof. Paper 46, p. 25, 1906.
STRATIGRAPHY 95

of Delight. The following identifications of the forms in the collection have been made by L. W. Stephenson:

Foraminifers.

Nucula sp.

Cucullaea sp.

Leda sp.

Nemodon sp.

Ostrea, meseuterica Morton?

Exogyra ponderosa Roemer.

Pecten sp.

Anomia argentaria Morton.

Liopistha (Cymella) bella (Conrad)?

Crassatellites? conradi (Whitfleld) ?

Lucina sp.

Cardium (Criocardium) dumosum (Conrad)?

Cardium sp.

Cyprimeria depressa Conrad.

Cymbophora sp.

Dentalium sp.

Turritella quadrilira Johnson?

Cerithium sp.

Concerning the age of the bed from which the fossils were obtained 

Stephenson says:

Compared with the standard Gulf series (Upper Cretaceous) section in the 

vicinity of Austin, Tex., the containing stratum corresponds in age to the lower 

part of the Taylor marl. There is nothing in the collection to indicate that 

the containing bed is as old as the Austin chalk of the type region.

TERTIARY ( ?) SYSTEM

Several small areas of gravel occur on the upland surface of the 

Athens Plateau between Athens and the headwaters of Holly Creek, 

in the Caddo Gap quadrangle. The hills capped by them range from 

about 850 feet above sea level at the south to about 1,000 feet at the 

north, and they represent remnants of the Hot Springs peneplain, 

which was produced about the beginning of the Tertiary period or 

sometime during that period. The position of the gravel on the 

crests of the hills shows that it was laid down by streams on this 

peneplain before the dissection of the peneplain was begun late in 

the Tertiary period or soon thereafter. They are therefore tentatively assigned to the Tertiary system. There is no evidence that 

the Tertiary sea ever extended far enough northwest of the present 

limit of Tertiary sediments, near Hope, Ark., about 45 miles distant, 

to lay down the gravel under discussion. The gravel was probably 

deposited by streams whose courses were markedly different from the 

present courses of Little Missouri and Saline Rivers, which now 

drain this part of the Athens Plateau. The deposits were formerly
96 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

more extensive than they now are, and doubtless most of the original 

gravel beds have been carried away by streams during the dissection 

of the peneplain.

The gravel nowhere appears to exceed 15 or 20 feet in thickness. 

It consists of subangular to well-rounded pebbles and cobbles as 

much as 10 inches in their longest dimension. Most of the pebbles 

are novaculite; the rest are sandstone. Owing to long exposure to 

weathering the novaculite pebbles have become somewhat porous and 

have lost the dense chalcedonic appearance that is usually shown by 

the novaculite.

QUATERNARY SYSTEM 

TERRACE DEPOSITS

The terrace deposits are found chiefly along Little Missouri, Saline, 

and Cossatot Rivers and Rolling and Muddy Forks, in the Coastal 

Plain along the southern borders of the quadrangles. Only small 

patches occur along these and other streams farther north.

Most of the terrace deposits in the Athens Plateau and the 

Ouachita Mountains form " second bottom" land and have been 

mapped with the alluvium where they have been mapped at all. In 

a few places terrace gravel a few feet thick occurs at a considerable 

height above the streams. The gravel caps a hill just north of the 

village of Caddo Gap and two hills just east of the village. It 

occurs 60 to 70 feet higher than the water above the dam on Caddo 

River at that place and about 680 feet above sea level. The gravel 

at Glenwood caps the small knob on which the high school is located 

and another about 1,000 feet northeast of the high school. The first 

of these occurrences is 115 feet above Caddo River at the ford south

of the town, or about 627 feet above sea level, and the second appears 

to be 15 or 20 feet higher. The highest observed deposit of the gravel 

above the streams in the northern parts of the quadrangles caps a 

low hill a little more than 2 miles west of Langley. This hill slightly 

exceeds 850 feet above sea level and rises about 150 feet above Little 

Missouri River at the ford on the west.

The terrace deposits in the southern parts of the quadrangles 

occupy benches that range from 35 to 150 feet above mean water 

level, and some deposits are strewn along the slopes between the 

different benches.

The deposits are in general unassorted mixtures of small and 

large pebbles and sand and are in most places overlain by a good 

soil. The gravel is of local origin, having been derived directly from 

the rocks of the Ouachita Mountains and indirectly from the same 

source through the gravel beds of Cretaceous age in these quadrangles. It is made up mostly of novaculite pebbles, which are partly
STEATIGRAPHY 97

rounded to well rounded and range in size from minute pebbles to 

cobbles a foot in diameter. A few pebbles are sandstone and quartz. 

The terrace gravel in the Coastal Plain so closely resembles the gravel 

of Cretaceous age that in places it is difficult and in some places 

apparently impossible to distinguish them. In such places the altitude of the gravel deposit, the character of the surface, and the assortment and size of the pebbles have to be considered in determining 

the age. These deposits range in thickness from a thin mantle to 

50 feet or more, but most of them are 15 to 20 feet thick. As a rule 

the largest patches contain pebbles and cobbles at the base and sand 

or loam at the top, whereas the smallest patches contain only pebbles 

and cobbles.

VARIOUS AGE DESIGNATIONS OF GRAVEL DEPOSITS

The several beds of gravel in the quadrangles that are older than 

the gravel of the alluvial deposits have been held by some geologists 

to be superficial and to be of post-Tertiary age, though other opinions 

have been held concerning them. The beds about which there has 

Jbeen much diversity of opinion include all those of the Trinity, 

Woodbine, and Tokio formations, the gravel of possible Tertiary age 

near Athens in the Caddo Gap quadrangle, and the gravel of the 

terrace deposits. The diversity of opinion has been due largely to the 

regional reconnaissance character of the studies of the deposits by 

the different geologists and also to the lack of topographic maps such 

as those that are now available.

Hill 68 in 1888 regarded the outcropping edges of the gravel beds 

in the Trinity, Woodbine, and Tokio formations as superficial deposits of post-Tertiary age and assigned to them the name " Plateau 

gravel."

Hay,87 who traced the northern border of the Cretaceous rocks of 

southwestern Arkansas, stated in his report of 1888 that the gravel 

deposits along this border are surficial deposits of post-Tertiary 

age laid down by " strong currents of water." The gravel deposits 

described by him occur in the Trinity, Woodbine, and Tokio 

formations.

McGee 68 in 1891 referred to the Lafayette formation the beds of 

gravel in southwestern Arkansas that are now classified as Lower 

Cretaceous, Upper Cretaceous, and Quaternary in age. Concerning 

the age of the Lafayette formation he says, " Its position in the biotic

69 Hill, K. T., The Neozoic Geology of Southwestern Arkansas; Arkansas Geol. Survey 

Ann. Kept, for 1888, vol. 2, pp. 28-42, 1888.

87 Hay, 0. P., The Northern Limit of the Mesozoic Rocks in Arkansas: Arkansas Geol. 

Survey Ann. Rept. for 1888, vol. 2, pp. 263 et seq., 1888.

88 McGee, W J, The Lafayette Formation: U. S. Geol. Survey Twelfth Ann. Rept., pt. 1, 

pp. 470-471, 1891.
98 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

scale is unknown, its meager flora combining Laramie (Cretaceous) 

and Pleistocene or modern features, and its still more meager fauna 

representing the entire Neocene."

Harris 69 in 1894 regarded the gravel beds of Cretaceous and 

Tertiary age of southwestern Arkansas as shore deposits " laid down 

under similar conditions, though by no means in the same geological 

epoch," and he thinks their "rearrangement presumably took place 

before the close of the epoch represented by the underlying stratified beds."

Ashley 70 in 1897 described as "overwash gravels," the gravel of 

possible Tertiary age near Athens, Ark., and also the gravel beds of 

Cretaceous age along the border of the Coastal Plain in southwestern 

Arkansas. He assigned them a post-Tertiary age.

Taff 71 in a report published in 1902 also regarded the out-cropping edges of the gravels in the Woodbine and Tokio, and a few 

areas of outcrop of those in the Trinity as surficial deposits and 

referred them and the terrace gravels to the Neocene (?), though 

he mapped as Trinity large areas of gravel that are assigned to 

that formation by the present writers.

Hayes 72 in 1903, after making a brief statement concerning the 

Trinity formation and its relations to the Paleozoic rocks in southwestern Arkansas, said, " Both Trinity and Paleozoic were * * * 

covered by a thin and irregular depos,it of coarse sand and gravel 

called the Lafayette."

Veatch 73 in 1906 made the statement that remnants or the redeposited remnants of the Lafayette formation are very common 

throughout the Coastal Plain in Arkansas and Louisiana, but he did 

not refer specifically to the gravel deposits of the De Queen and

Caddo Gap quadrangles. He did say, however, that " Portions of 

the weathered outcrops of the Bingen and Nacatoch sands have, been 

mistaken 74 for these surficial [Lafayette] beds."

Branner 75 in 1908 in his description of kaolin deposits between 

Murfreesboro and Delight called the gravel there the Lafayette 

gravel and assigned it a Pleistocene age. These gravels are now

89 Harris, G. D., The Tertiary Geology of Southern Arkansas: Arkansas Geol. Survey 

Ann. Rept. for 1892, vol. 2, pp. 7-9, 1894.

70 Ashley, G. H., Geology of the Paleozoic Area of.Arkansas South of the Novaculite 

Region: Am. Philos. Soc. Proc., vol. 37, pp. 308-306, 1897.

71 Taff, J. A., Chalk of Southwestern Arkansas with Notes on Its Adaptability to the 

Manufacture of Hydraulic Cements: U. S. Geol. Survey Twenty-second Ann. Rept., pt. 3, 

pp. 694-696, 1902.

72 Hayes, C. W., Asphalt Deposits of Pike County, Ark.: U. S. Geol. Survey Bull. 213, 

p. 353, 1903.

78 Veatch, A. C., Geology and Underground Waters of Northern Louisiana and Southern 

Arkansas: U. S. Geol. Survey Prof. Paper 46, pp. 44-46, 1906.

w Veatch cites the above-mentioned reports by Hill and Taff.

76 Branner, J. C., The Clays of Arkansas: U. S. Geol. Survey Bull. 351, pp. 148-163, 

1908.
IGNEOUS ROCKS 99

regarded by the present authors as being a part of the Tokio formation.

Purdue 70 in 1908, in describing the geology of the peridotite area 

at the American diamond mine near Murfreesboro, Ark., says, " The 

top of the ridge [at the mine] is covered to a depth of 10 to 12 feet 

with 'plateau gravel' (Lafayette formation) cemented into a conglomerate." This gravel is now classified as the lowest bed of gravel 

of the Tokio formation.

ALLUVIUM

Most of the streams in the Athens Plateau and Ouachita Mountains 

flow on bedrock and are bordered by cliffs and steep slopes or by 

only small patches and belts of alluvium, but most of the streams 

in the Coastal Plain flow in flat-bottomed valleys and are bordered 

by flood plains, some of which are 2 to 3 miles wide. Although 

fine and coarse gravel makes up a large part of the valley filling, the 

surface is usually covered with rich loam and sand, and most of it 

makes good farm land. These gravel deposits in the Coastal Plain 

have been derived from erosion of the outcropping edges of older 

gravel deposits of the region, though some of them have been carried 

by the streams from the Ouachita Mountain region. They thus do 

not differ from the gravel of Cretaceous age already described, except in their distribution and lack of assortment. Little is known 

of the thickness of the alluvium, but it is probably less than 25 feet 

at most places.

IGNEOUS BOCKS" 

GENERAL, FEATURES

Peridotite, the only igneous rock observed by the authors in the 

quadrangles here described, is exposed in four places near Murfreesboro in the Caddo Gap quadrangle, and three of these exposures 

have yielded diamonds. The exposure that was first discovered 

and that has been known to geologists since 1842 is 2^ miles southsoutheast of Murfreesboro, near the confluence of Prairie Creek with 

Little Missouri River, and is hence named the Prairie Creek peridotite area. (See pi. 10.) Diamonds were discovered on it in 1906, 

and since then more than 10,000 diamonds, ranging in weight from 

a small fraction of a carat to 40.23 carats, have been taken out. The 

mines that are operated on it are the Ozark, Mauney, and Arkansas.

TO Purdue, A. H., A New Discovery of Peridotite in. Arkansas: Economic Geology, vol. 3, 

No. 6, p. 526, 1908.

"Much of this section has been written by C. S. Ross, to whom the specimens of the 

rocks were submitted for microscopic study. Other descriptions of the peridotite by 

Messrs. Ross and Miser have been given in the following recent articles: Diamond-Bearing 

Peridotite in Pike County Ark1.: Econ. Geology, vol. 17, pp. 662-674, 1922; U. S. Geol. 

Survey Bull. 735, pp. 279-322, 1923; Smithsonian Inst. Ann. Rept. for 1923, pp. 261-272. 

1925.
100 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

The other exposures of peridotite are all within an area of 1 square 

mile about 2 miles northeast of the Prairie Creek area and 3 miles 

east-southeast of Murfreesboro. Two of these, the Kimberlite and 

American areas, are so named from the mines located on them, and 

the third, the Black Lick area, is at and near a locality known as 

the Black Lick. (See pi. 14.) The Kimberlite and American areas 

have been prospected on a small scale, and each has yielded a small 

number of diamonds. The Black Lick area has been prospected 

less than any of the others and has thus far produced no diamonds. 

A 5-foot dike of ouachitite was discovered a few years ago by 

Mitchell 78 at a locality 7 miles east of Gillham in the southeast part 

of sec. 9, T. 7 S., R. 30 W. Weathered boulders on a hill slope 

attracted his attention and led to the discovery. The rock, according 

to him, is a black, heavy material, with biotite, augite, and pyrite 

recognizable in hand specimens.

PRAIRIE CREEK PERIDOTITE AREA 

LOCATION AND TOPOGRAPHY

The Prairie Creek peridotite area is roughly triangular and comprises about 73 acres. (See pi. 10.) The surface is gently rolling 

and has an altitude of 340 to 380 feet, except along its northwest 

margin, where there are three knobs or hills, known as West, Middle, 

and East Hills, that rise to altitudes of 401, 415 to 420, and 441 feet, 

respectively. This area is joined on the southeast by rolling country, 

but along other parts of its boundary it is joined by the low, nearly 

level valley floor of Little Missouri River and some of its tributaries. 

The surface of most of the valley floor is between 315 and 340 feet 

above sea level, though near the Ozark mine it attains an altitude of

a little over 355 feet.

ROCKS ASSOCIATED WITH THE PERIDOTITE

The peridotite area is adjoined along most of its east side by clay 

and sand of the Trinity formation and on its north and west sides: 

and much of its south side by alluvium. (See pi. 10.) The alluvium 

conceals not only the Trinity formation, but also parts of the margin 

of the peridotite body and possibly many dikes that radiate from the 

exposure. On Prairie Creek, near its mouth, erosion of the alluvium 

has revealed sand of the Trinity formation at three places and a 

peridotite dike at one place.

Many boulders of Carboniferous sandstone are in the bank of Little 

Missouri River just below the mouth of Prairie Creek, and although 

they are not in place they are probably near the parent ledges.

78 Mitchell, G. J., Antimony in Southwestern Arkansas: Eng. and Mln. Jour.-Press, vol. 

114, p. 455, 1922. Also map accompanied by letter dated Sept. 7, 1923.
U. 8. GEOLOGICAL SURVEY BULLETIN 808 PLATE 10

EXPLANATION 

SEDIMENTARY ROCKS

Trinity forination 

UNCONFORMITY

Jackfork(?) sandstonem

IGNEOUS ROOKS 

Peridotite)

'I

oIntrusive peridotite

Drill hole 

(Number, tame at in text)

X1

First diamond found in Pike County. 

Ark., was discovered in August, 1906, 

byJ. W. Huddleston

X2

Specimen of "green ground" containing 

diamond .was found

Canary-colored diamond weia.....D __.

carats was found in May, 1917, by

Lee Wagner

Mine Workings

Contour interval 5 feet 

Datum, is mean sea level

GEOLOGIC MAP OF THE PRAIRIE CREEK AREA OF PERIDOTITE IN T. 8 S., R. 25 W., 2^ MILES SOUTH-SOUTHEAST OF MURFREESBORO, PIKE COUNTY, ARK.

Surveyed with piano table in 1916_by H. D. Miser
TJ. S. GEOLOGICAL SURVEY BULLETIN 808 PLATE 11

A. INTRUSIVE I'ERIDOTITE (" HARDEBANK ") IN THE NORTHERN PART OF 

THE MAUNEY MINE, NEAR MUHFREESBORO, ARK.

£. ALTERED VOLCANIC BRECCIA ("BLUE GROUND") IN CUT OF OZARK MINE 

NEAR MURFREESBORO, ARK.

The bedding dips about 30° W.
IGNEOUS ROCKS 101

Boulders of peridotite also occur at the same locality. Their source 

is not known, but they were probably derived from one or more dikes 

that are now concealed.

A small part of the east side of the peridotite exposure and a 

greater part of its south and southwest sides are adjoined by exposures of sandstone of Carboniferous age, which may be the Jackfork 

sandstone. The sandstone is massive and gray, greenish gray, and 

brown, and some of it has been changed to a hard compact quartzite. 

A mass of fine-grained gray quartzite about 100 feet long and 50 

feet wide occurs on the crest of East Hill. It was perhaps derived 

from the Jackfork sandstone and included in the peridotite magma 

during the upward movement of the magma toward the surface.

Terrace gravel, as much as 10 feet thick, rests upon the Carboniferous sandstone in a very small area on the west point of West Hill,

and similar gravel overlain by clay rests upon the Trinity formation 

southeast of the Arkansas mine. These terrace deposits are from 350 

to 370 feet above sea level and have the same altitude as the long 

north-south terrace on which the town of Murfreesboro stands. The 

gravel consists of well-rounded pebbles and cobbles of variegated 

novaculite.

The black soil overlying the peridotite at the Ozark, Mauney, and 

Arkansas mines contains numerous pebbles of novaculite to a depth 

of 1 or 2 feet. The greatest altitude at which the pebbles in the soil 

occur is nearly the same as that of the above-mentioned terrace gravel, 

and this fact suggests that they have been derived from a terrace 

deposit that was laid down on the peridotite. If such a deposit was 

laid down, Little Missouri Kiver must have once flowed across the 

southeastern part of the peridotite exposure.

CHARACTER OF THE PERIDOTITE

General features. Although the Prairie Creek peridotite area 

comprises 73 acres, the exposures of the hard, unweathered rock do 

not exceed 12 acres. The depth of the weathered material has not 

been determined, though it has been shown by pits and drill holes to 

be at least 205 feet.

The weathered peridotite is a soft earth or a fairly soft rock. 

It shows many shades of green, blue, and yellow, and the rocks t>f 

these colors are known by the miners as " green ground," " blue 

ground," and "yellow ground." The soft earth at the surface is 

black from the presence of organic matter and is known as " black 

ground." It is waxy like gumbo and is as much as 4% feet thick 

here and there, though it is usually only about 1 foot thick. At 

6242 29 8
102 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

places fully half of the black ground is composed of well-rounded 

novaculite pebbles and angular fragments of sandstone and quartzite.

The peridotite appears to be divisible into three rather distinct 

types. One is a massive intrusive rock; another is a volcanic breccia, 

which is almost identical with the first in mineral composition and is 

probably the pyroclastic equivalent of that rock; and the third comprises volcanic tuff and fine-grained breccia. The distribution of 

these types is shown in Plate 10.

The firs.t two types are nearly black when fresh and weather to 

dingy olive-green; the third type is light blue.

Intrusive peridotite. The intrusive peridotite is the surface rock 

in two areas. One area extends from the northern part of the 

Ozark mine across the northern part of the Mauney mine and thence 

westward and south westward beyond Middle Hill. (See pi. 11, A.) 

The other area lies between the Arkansas mine and West Hill.

The intrusive peridotite is very similar in appearance to the associated volcanic breccia and is no doubt its hypabyssal equivalent. 

Different occurrences of the intrusive type differ very little in color 

and mineral composition. Where unaltered it is a very dense porphyritic rock, which is dull black, greenish black, or brownish black. 

The fresh rock is hard and exceedingly tough and for this reason is 

called " hardebank " by the miners. Olivine forms the only phenocrysts of appreciable size occurring in the rock. Their color is nearly 

white when the olivine is unaltered, but many of the aggregates of 

secondary minerals derived from them are nearly black. The greenish or brownish black groundmass is fine grained and has a dull surface on fresh fracture. A very few grains of chromite have been 

observed with the unaided eye.

The microscope shows that the rocks are composed essentially of 

olivine phenocrysts in a groundmass of pale red-brown mica. (See 

pi. 12.) The mineral composition of a typical specimen is as follows:

Mode of intrusive peridotite

Augite _ ______ _______________ 6

Olivine _ _ __ _____________ 11

Serpentine (derived from olivine)_________________ 24

Phlogopite_______________________________ 56

Perovskite __________________________ 1

Magnetite_______________________________ 2

100

In some specimens the alteration of the olivine to serpentine is 

almost complete, but in many of the larger phenocrysts alteration 

has occurred only along the borders and cracks. Many of the
IGNEOUS HOCKS 103

phenocrysts have a fine euhedral outline, even though completely 

altered to serpentine, but others have a rounded outline. Most of 

the olivine-serpentme areas are surrounded by a narrow reaction rim 

of the brown mica phlogopite, which, unlike the other phlogopite, 

contains no poikilitic inclusions. In thin sections the serpentine is 

colorless or pale yellow, and much of it contains minute inclusions 

of secondary magnetite, which developed during the alteration of 

the olivine.

The most abundant mineral of the groundmass is phlogopite, 

which occurs in fine-grained aggregates, in large anhedral crystals, 

and as narrow reaction rims around olivine grains. Most of the 

phlogopite is poikilitic and incloses all the other minerals of the 

groundmass. Its color in thin sections is usually very pale yellow to 

reddish brown, but some grains are rose-pink in the direction of 

maximum absorption. Most of the phlogopite is unaltered, but 

some of the fine-grained groundmass aggregate of mica is pale green 

through partial alteration of the mica to chlorite.

Light-colored augite is found in most of the rocks of this type, 

and where best developed it occurs in euhedral needles from 0.05 

to 0.15 millimeter in length. (See pi. 12, B.) In other specimens 

it forms very small irregular grains. Small black crystals of magnetite and rounded or octahedral crystals of yellow perovskite are 

abundant accessories.

Inclusions of several kinds have been noted in the intrusive peridotite. One kind, which may represent altered limestone inclusions, 

forms subangular areas as much as 3 inches in their longest dimension composed mostly of very fine grained serpentine, which is 

greenish brown to nearly black in the hand specimen and is surrounded by thin layers of light-green coarser-grained serpentine.

Small shale fragments are present in much of the rock, and they 

have become dull green through the development of minute crystals 

of chlorite. No large fragments of black shale like those in the 

breccia were observed. Another kind of inclusion appears to have 

been originally a very coarse grained igneous rock composed largely 

of hypersthene. The original minerals have been completely altered, 

and the rock is now composed of serpentine and secondary amphibole and pyroxene. The amphibole is rose-purple, pleochroic, manganese-bearing tremolite, and the green pleochroic pyroxene is intermediate between aegirite-augite and diopside.

The diamonds that have been recovered from the soft decomposed 

material derived from the intrusive type of peridotite are said to 

be few and small.
PLATE 12

A. Nearly fresh rock. Large phenocrysts of olivine show partial alteration to 

serpentine. Dark-gray groundmass is fine-grained aggregate of phlogopite, augite, and magnetite. Enlarged 15 diameters.

B. Rock from summit of Middle Hill. Phenocrysts of olivine partly altered 

to serpentine. Groundmass is phlogopite containing small prisms of 

augite and black grains of magnetite and perovskite. Enlarged 50 

diameters.

104
U. S. GEOLOGICAL SURVEY 

PHOTOMICROGRAPHS OF INTRUSIVE PERIDOTITE ("HARDEBANK") FROM PRA
U. S. GEOLOGICAL SURVEY 

A. PHOTOMICROGRAPH OF IJLL'K-GRAY TUFF FROM DRILL HOLE 

NO. 3 NEAR ARKANSAS MINE, NEAR MURFREESBORO, ARK.

Large fragments are metamorphosed shale. Crystal in upper right corner is phlogopite. Groundmass is an aggregation of alteration minerals. Enlarged 15 diameters

Ji. POLISHE

FROM SO

BORO, AR

Composed of a

tains pheno
IGNEOUS ROCKS 105

Volcanic breccia. The volcanic breccia is a pyroclastic rock similar to and closely associated with the porphyritic intrusive peridotite. It is the surface rock over a fairly large area extending from 

the southern parts of the Ozark and Mauney mines southward to 

and beyond the Arkansas mine. It has yielded most of the diamonds 

taken from these three mines. Although the distribution of the 

breccia is shown on the accompanying map (pi. 10), the boundary 

line that represents the contact between it and the intrusive peridotite is not accurately drawn, because there are comparatively few

 exposures of unaltered rock.

The breccia as it is revealed at the surface is weathered and has 

changed to clay or soft rock except in three or four small areas near 

the shed on the Arkansas mine, where there are exposures of rock 

that is weathered very little. In these areas it is a very firmly 

cemented, tough pyroclastic rock. An examination of the leastweathered specimens of it show them to be composed of rock fragments that differ greatly in texture, some of the fragments being 

porphyritic peridotite and others being completely aphanitic. The 

original olivine phenocrysts are now light-colored aggregates of serpentine, some containing cores of fresh olivine. A few flakes of 

<:lark mica can usually be recognized in the hand specimen. The 

microscope shows that the rock differs little from the porphyritic 

intrusive phases. Olivine phenocrysts partly altered to serpentine 

are abundant, and a few small phenocrysts of phlogopite are present. 

The groundmass is composed of a fine-grained aggregate of phlogopite, augite, magnetite, and perovskite. The shale inclusions are 

much altered and are now composed largely of very small quartz 

and augite or chlorite grains.

Some of the altered breccia is clay, but some is fairly hard rock. 

A small quantity of the clay is yellow and is known as " yellow 

ground," but the soft rock and most of the clay have a dirty-green

 color and are known as " blue ground " or " green ground." Most 

of the " blue ground " or " green ground " as revealed in gullies is 

a breccia (pi. 13, B) and ,is fairly hard, though the hard rock 

softens on long exposure so that it can be washed for the recovery 

of the diamonds. The "bjue ground" shows bedding at a few 

places; the best exposure is near the southwest end of the large 

northeastward-trending cut of the Ozark mine. There the bedding 

<_Iips about 30° W., and the several layers show not only a difference 

in color but also a, difference in the size of the rock fragments composing the breccia. (See pi. 11, B.)

The " blue ground " is composed largely of angular and subangular 

fragments of .igneous rock but contains many irregular fragments 

of shale, clay, and sandstone. Most of the fragments of sedimentary
106 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

rocks are less than 1 inch in their longest dimension, though some 15 

inches long were seen. The fragments of shale and sandstone have 

been derived from rocks of Carboniferous or earlier age, and most or 

all of them have probably been carried upward hundreds or thousands 

of feet from their source.

The f ragments. of igneous rock in^ the " blue ground " reach a 

maximum size of about 6 centimeters and average less than 2 centimeters in diameter, but some layers consist entirely of fine material 

a few millimeters in diameter. (See pi. 13, B.) The olivine in the 

" blue ground " has completely disappeared but is represented by 

light-colored areas 1 centimeter or less in diameter. The individual 

rock fragments and their difference in texture can be easily recognized. The fine-grained layers are now a friable granular rock, in 

which weathered serpentine is the only recognizable mineral.

A number of minerals that are rarely observed in hand specimens 

or in thin sections of the volcanic breccia are obtained as concentrates 

by washing the soft, decomposed rock for the recovery of the diamonds. The minerals, not including the diamonds, are hematite, 

limonite, barite, colorless quartz, amethyst quartz, magnetite, schorlomite (or melanite), chromite, almandite, pyrope, pyrite, diopside, 

and epidote. The proportions of these minerals differ somewhat 

from place to place, but in general those named first are the most 

abundant and the last the least abundant. All the minerals here 

mentioned, except possibly the diopside and epidote, occur in larger 

quantities than the diamonds. An assay of a sample of the concentrates from the Arkansas mine revealed a small quantity of 

platinum $0.40 per ton (platinum at the time of assay was worth 

$150 to $160 per ounce). 79 The assay was made several years ago by 

a reliable firm for the Arkansas Diamond Corporation. The platinum presumably occurs in the chromite; no flakes of it have ever, 

so far as known, been observed in the concentrates from the mines. 

It therefore does not occur in workable quantity.

The barite, colorless quartz, and amethyst quartz are described 

under the heading "Veins in the peridotite," on page 109. The 

magnetite occurs as irregular and octahedral grains as much as 10 

millimeters in their longest dimension, and part of it, like the barite 

and quartz, is present in veins in the peridotite. The hematite and 

limonite occur as irregular and rounded grains as much as 10 millimeters in their longest dimension, but some grains have the forms 

of pyrite crystals, from which they have been derived. Some of 

the hematite and limonite have, however, been derived from magnetite. The chromite is present as irregular black grains 8 millimeters

70 Information furnished by John C. Peay, manager of the Arkansas Diamond Corporation.
IGNEOUS ROCKS 107

or less in their longest dimension. A mineral that is either melanite 

or schorlomite is apparently more abundant than the chromite; the 

grains are also irregular in shape and are as much as 7 millimeters 

in their longest dimension. The almandite is dark red and occurs 

in irregular grains, the largest 6 millimeters long. Crystals of this 

mineral are very rare. The pyrope is present in about the same 

quantity as the almandite; its grains are pale red to hyacinth-red, 

irregular, and as much as 4 millimeters in length. The epidote and 

diopside occur as brown and green prismatic grains, and their maximum length is about 3 millimeters.

The diamonds from the volcanic breccia as well as the few diamonds from the intrusive peridotite are described in the section on 

economic geology, on pages 147-150.

Tuff and fine-grained breccia. The tuff and fine-grained breccia 

are exposed in a large area, which extends from West Hill eastward to the Arkansas mine and thence northward nearly to the 

crest of East Hill, and in tAvo small areas, one in the Ozark mine 

and the other in a gully in the northeastern part of the Arkansas 

mine. The boundaries of the areas of exposure as represented on 

Plate 10 are somewhat indefinite on account of the small number 

of rock outcrops.

The only locality that reveals these rocks in contact with the volcanic breccia is in the large northeastward-trending cut of the Ozark 

mine. There the northernmost exposures of a blue rock (tuff or finegrained breccia) shoAV it to be in contact Avith " yellow ground," 

which is probably derived from intrusive peridotite. The contact is 

distinct and dips about 70° NW.

These rocks as they are revealed at the surface are light bluish 

gray and are fairly hard, though at most places the hard rock has 

been concealed by soft blue earth. The black soil (" black ground ") 

which is so characteristic of the areas of the intrusive peridotite 

and volcanic breccia is present in parts only of the areas of the tuffs.

The blue-gray tuff varies greatly in texture. Some specimens are 

composed of fragments that average less than 1 millimeter in diameter and have an even-grained lithoidal appearance. Others contain 

similar material inclosing fragments as much as 10 millimeters in 

diameter, and still others are made up largely of such fragments with 

only a little fine-grained matrix between them. Reddish-brown 

phlogopite occurs in fine fresh flakes commonly 1 millimeter or less 

in diameter, but some of them reach 3 millimeters. Many small white 

or pale-yellow grains are serpentine, probably derived from olivine.

The microscope shoAvs that the most abundant mineral of the 

rock is a pale blue-green chlorite, which is secondary to an older
108 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

mineral or more probably to the very fine grained aggregate that 

formed the groundmass of the original rock. In some specimens 

these chloritic grains are angular in outline and are formed of radial 

aggregates with a small amount of fine-grained phlogopite remaining 

unaltered. This fact leads to the conclusion that the original rock 

was an olivine-mica peridotite like the intrusive rock and the volcanic 

breccia. Accessory minerals in the tuff are magnetite, secondary 

calcite, and fine-grained opaque aggregates. Shale fragments are 

abundant in the tuff in many places, and fine-grained sandstone fragments are less abundant. (See pi. 13, A.) The smaller inclusions 

have developed various amounts of chorite, but the larger ones are 

not greatly metamorphosed, and most of them are only slightly 

indurated.

Alteration is much more complete in the light blue-gray volcanic 

tuff than in the intrusive rocks and the volcanic breccia, and so the 

original composition of the tuff is very much more problematic, but 

there is no reason to suspect any great difference in the mineral composition of the original forms of these three classes of rocks. It 

is evident, however, that the later history of the tuff is different 

from that of the other rocks of igneous origin. The tuff contains 

much chlorite, whereas the other rocks contain little or^none of that 

mineral. It is very probable that the different types of alteration 

shown by the igneous rocks resulted from different conditions at the 

time of extrusion.

The dikelike injection breccia is similar in all ways to the tuff 

and in the hand specimen is almost indistinguishable from it. Breccia of this sort is exposed as a dike in a gully in the northern part of 

the Arkansas mine. The dike is about 10 feet wide and trends northeast. The contacts with the volcanic breccia ("blue ground") on 

each side of the dike are concealed by loose surficial material, and 

the dike can not be followed more than 25 or 30 feet.

Associated with and grading into the purely pyroclastic tuff are 

green-gray rocks which resemble it and can not be sharply delimited 

from it. These rocks contain various proportions of material that is 

not derived from the peridotite. Quartz is by far the most abundant 

foreign mineral, but alkalic feldspar is not uncommon. The quartz 

shows enlargement, but the presence of well-rounded cores in many 

of the grains leaves no doubt that the quartz had a sedimentary origin. It seems clear, therefore, that the parts of the tuff beds were reworked and received an admixture of quartz derived from near-by 

sand and sandstone. Quartz-bearing tuff is exposed on the crest 

and north end of West Hill, where it protrudes as hard, rough boulders, whose distribution and shape suggest that the rock is in beds
U. 8. GEOLOGICAL SURVEY BULLETIN 808 PLATE 14

KIMBERLITE 

BUNGALOW

WAREHOUSE

SW.X4 NW./4

GEOLOGIC MAP SHOWING OCCURRENCE

OF THE PERIDOTITE AND OTHER ROCKS AT THE

KIMBERLITE AND AMERICAN MINES.

IN SEC. 14, T. 8 S.. R. 25 W.. ARK.

100 100 200 300 Feet

SE./4 NW./4

EXPLANATION

Surface clay, sand, and gravel overlying chieffo Trinity formation and

 : _ : Tokio formation (Upper Cretaceous)

some peridotite

-WT^'-'V-;' Peridotite

'"%''"''}&'' Trinity formation (Lower Cretaceous)

 Drillhole

a Shaft

oo Pits

^ U Cuts and trenches

[SI House

NW./4 SW./4 SW./4

GEOLOGIC MAP SHOWING OCCURRENCE

OF THE PERIDOTITE AND OTHER ROCKS AT THE

BLACK LICK, IN SEC. 23, T. 8 S., R. 25 W., ARK.

MAPS SHOWING THE DISTBIBUTION OF THE PERIDOTITE AT THE AMERICAN AND KIMBERLITE MINES AND AT THE BLACK LICK, IN T. 8 S., R. 25 W., PIKE COUNTY, ARK
IGNEOUS ROCKS 109

with a northerly strike and a dip of 90°. Numerous clay like inclusions, as much as half an inch in their longest dimensions, are present. 

Few or no diamonds have been obtained so far as knOAvn from the 

tuff and fine-grained breccia.

VEINS IN THE PERIDOTITE

Veins composed of quartz and barite cut the volcanic breccia in 

the Ozark mine, and the occurrence of fragments of quartz on the 

surface at the Arkansas mine indicates that such veins are present 

there also. These veins are rare and attain a thickness of not more 

than 2 inches. The barite occurs as crystals next to the breccia, and 

the quartz surrounds and incloses the crystals, showing that the 

barite was deposited in fissures in the peridotite and was followed by 

the quartz. Some of the quartz, especially that next to the breccia,

is chalcedony, but much of it is massive and some occurs as crystals 

lining cavities in the veins. These crystals range from a small fraction of an inch to 2 inches in their longest dimensions and many are 

clear and transparent, though most of them are milky. Much of the 

massive quartz and many of the crystals have a pale amethyst color. 

On the Arkansas mine the amethyst has been found most abundant 

near the west sluice trough.

Veins consisting of barite, altered serpentine, and small crystals 

of magnetite were observed in the intrusive peridotite at the Mauney 

mine. Some are as much as 2 inches thick. One vein of barite a 

quarter of an inch thick was observed in the altered volcanic breccia 

in the Arkansas mine. The barite in these veins and the loose fragments of it observed at different places in the mines is blue, white, and 

colorless. Some of it occurs in tabular crystals and sheaflike aggregates of crystals.

A pocket of vein material is present at the contact of the weathered 

intrusive peridotite and the tuff in the north side of the large northeastward-trending cut of the Ozark mine. The pocket has a maximum dimension of 2 feet and consists of white coarse-grained calcite 

and a tough cream-colored mineral known as paligorskite, which is 

a hydrous silicate of aluminum and magnesium.

A few veins of paligorskite less than half an inch thick occur in 

the altered volcanic breccia in the Arkansas mine. A small quantity 

of calcium, which may be due to the presence of tremolite, is present 

in the mineral.

DIKE NEAR MOUTH OF PRAIRIE CREEK

The peridotite dike represented on Plate 10 near the mouth of 

Prairie Creek was exposed during the late eighties on the left bank 

of Little Missouri River just below the mouth of this creek, but
110 DE QUEEN" AND CADDO GAP QUADRANGLES, ARKANSAS

since then the Little Missouri has shifted its channel to the south 

so that the exposure is now in the bed of the creek. A pit was dug 

by Mr. Miser at the water's edge until the dike was reached. It is 

there about 8 inches wide, and the rock has altered to a soft yellow 

earth in which yellow mica and many inclusions are conspicuous.

Specimens of the fairly hard rock collected in 1900 by J. A. Taff 

were examined by the writers. The igneous portion that cements 

the inclusions is yellowish brown and is composed of a groundmass 

weathered to yellow compact clay and of brown phlogopite in crystals, the largest 2 millimeters in their longest dimension. Owing 

to the advanced stage of weathering no other minerals can be 

recognized.

KIMBERLITE PERIDOTITE AREA

The Kimberlite peridotite area is in a cleared tract on the crest 

of a low hill in the SW. % NW. ^ sec. 14, T. 8 S., R 25 W. The 

map of this area (pi. 14) shows by patterns only the observed and

reported occurrences 

of the rocks. The 

peridotite is not revealed in natural exposures. It is covered 

with 3^ellow to red 

surficial clay, a few 

?....?_____^OFeet inches to a few feet

FIGUBB 4. Section of dike of weathered peridotite cutting thick, derived largely 

the clay of the Trinity formation at the Kimberlite from the weathering 

mine, Pike County, Ark. This dike is revealed in the / ,1 rp , -forma 

exposure that is farthest east at this mine OI me iriniiy 101 mation, which at the surface at this locality consists of yellow, red, and brown clay. The 

dike that is exposed in the trench farthest east at the Kimberlite mine 

(fig. 4) is probably an eastward continuation of the larger mass of 

peridotite in this area. The form of the intrusion, to judge from 

present exposures, is that of a crescent-shaped dike which strikes 

northeast and has a length of at least TOO feet and a width of possibly 

100 feet at the surface.

Exposures indicate that the clay of the Trinity in contact with the 

peridotite was metamorphosed into a vitrified clay for a few feet, at 

least, away from the contact when the peridotite was intruded, but 

since then the clay has weathered so much that it is now only a little 

harder and lighter in color than the clay that was not metamorphosed. 

Many inclusions of black shale, derived from the Paleozoic shale beneath, occur in both the fresh and the disintegrated peridotite, and 

some of them reach 2 inches in diameter. They are baked by heat from 

the intruding peridotite, and although they are much weathered near
IGNEOUS BOOKS 111

the surface tlfey remain harder than the ordinary black shale, which 

is widely exposed in the Ouachita Mountains on the north. Veins 

of white barite and of 37 ellow paligorskite with the fibers parallel to 

the walls of the veins cut both the fresh and the altered peridotite.

The hard, unaltered peridotite, known locally as "hardebank," 

occurs as two small patches a few feet across in the southwestwardtrending trench at the west boundary of the mass. Elsewhere it has 

disintegrated to a soft green and yellow earth. The unaltered rock 

is dense, tough, porphyritic, and greenish black and is similar to the 

intrusive peridotite found in a part of the Prairie Creek area.

AMERICAN PERIDOTITE AREA

The American peridotite area lies on a steep wooded north slope

at the northeast end of a ridge in the NE. 1/4 SW. 1/4 sec. 14, T. 8 S., 

R. 25 W. The ridge at this locality is between 550 and 600 feet above 

sea level and rises about 100 feet above a wet-weather branch that 

is just east of the house shown on Plate 14. It is capped by the 

Tokio formation, which consists of about 15 feet of interbedded 

clay and gravel and of a basal layer of conglomerate 12 to 15 inches 

thick, composed of novaculite pebbles cemented together by brown 

iron oxide. The Tokio is underlain by the Trinity formation, represented here by clay, and by the peridotite that has been intruded 

upward into the Trinity.

Most of the peridotite has been deeply weathered, and only a few 

small fragments of it were found at the surface. The Trinity and 

the peridotite are concealed by red and yellow surficial clay in which 

there are many pebbles and some fragments of conglomerate. The 

surficial clay on the lower half of the hill slope is black and is called 

" black ground."

The peridotite at the time of examination was exposed in shallow 

pits, trenches, and cuts not more than a few feet deep and in a 

shaft and a tunnel. Its superficial portion has decomposed 'to a 

soft greenish earth, locally known as " green ground," the more 

weathered portions of which have changed further to a yellowish 

earth called " yellow ground."

The relation of the peridotite to the sedimentary rocks is represented in the accompanying section (fig. 5), which shows that the 

peridotite penetrates the Trinity formation, but does not penetrate 

the Tokio formation. The only noticeable effect of metamorphism is 

that the clay of the Trinity has in places been baked to a hard gray 

stone for a distance of 2 feet away from its contact with the peridotite.

The shape and full extent of the peridotite mass are not known, 

because of the small number of exposures. The weathered rock
tn 

c5

sw -5

_c

A -1

 . ;::'-V.:V::->y^rrrwT-^_ t-> ^rrrrr^^-: .' . .-. : ' .' .-. ; :'-: : : : ::^tv7

§ ~~~

100 0 IOO

W$!K $ft

_0> 

3 * +,= 

"^=^~^%~^

200 300 

-T n i =» 

x^/Jr/ . =:^£HK= 

"'A- Hi-^q^i^q 

Tokio Peridotite Trinity 

formation formation

^IGUBE 5. Structure section through the American mine, Pike County, Ark., along the line A 

to the Trinity and Tokio formations 

P^ ' o'^ l~b S"i-q > 2^^^. i"r?

UQ rn <i ? CD ^^ O i 1> ^< CD c/j P-1 HJ CD 00 ^^ 50 ^^ H M_^tS"- J -

TS

 n

. o

if s

g S § 1

^ ts.

s: » 4 H

O O !- w _

tlT1 ^ *7 i ^ > i C^

^^ " w ? J _ I I I

^ N 0 

'

p OQ
IGNEOUS BOCKS 113

basal part of the Tokio formation, which here consists of 30 feet of 

gravel and a basal layer of conglomerate composed of novaculite 

pebbles cemented together by brown iron oxide. The Trinity formation and the peridotite which has penetrated the Trinity underlie 

the Tokio.

The peridotite lies on the upper part of the gentle west slope of 

the ridge. The occurrence of a black soil at this locality led someone to make a very small opening in search of peridotite where a 

yellowish-green earth was poorly exposed. This pit was deepened 

to 7 feet in 1912 by Mr. Miser, who also made another pit 6 feet 

deep 900 feet farther east. Since 1912 the first pit has been enlarged and other shallow pits have been made near it and also near 

the one farthest east. All of the pits reveal altered peridotite, and 

they comprise the only exposures of this rock in the vicinity. The

only exposures of the Trinity, which is represented here by clay, 

are farther down the slope from the pits of the Black Lick. The 

peridotite exposed in the pits at the Black Lick has weathered to a 

soft yellowish-green earth which still retains structural features indicating that the unweathered rock was a volcanic breccia composed of 

fragments of porphyritic peridotite and some fragments of clay.

The pits that are 900 feet east of the Black Lick are in a timbered 

area which is comparatively level over several acres. The surface 

material consists of a black gumbo soil mixed with some water-worn 

gravel and is 2i£ feet thick. Below this black soil yellowish green 

earth derived from peridotite was penetrated in all the pits. Although the material has disintegrated so much that microscopic study 

is impossible, the texture is clearly porphyritic, the phenocrysts being 

serpentinous pseudomorphs after olivine, whose outlines are in many 

places sharply defined and well preserved.

The extent of the peridotite in the vicinity of the Black Lick is 

not known, but the altered rock exposed in the pits is probably all 

within a single area. If this is true, it will be readily understood 

from the relations of the peridotite to the Tokio stated above that 

pits or drill holes on the crest of the ridge must pass through the 

Tokio before the peridotite is reached.

RELATION OF THE PERIDOTITE TO THE OTHER IGNEOUS ROCKS OF ARKANSAS

The peridotite in the Caddo Gap quadrangle is, as has been pointed 

out by Williams,80 related in age to the other igneous rocks of 

Arkansas. The igneous rocks ,in other parts of the State consist of 

nephelite syenite, pulaskite, and related intrusive rocks and occur in 

four small areas in the eastern part of the Ouachita Mountain region

*°Williams, J. F., The Igneous Rocks of Arkansas: Arkansas Geol. Survey Ann. Rept 

for 1890, vol. 2, p. 391, 1891.
114 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

and in the northwest border of the Gulf Coastal Plain. One of these 

areas is in the Fourche Mountain region, near Little Rock, Pulaski 

County; a second is near Bauxite, Saline County; a third is at 

Magnet Cove, Hot Spring County; and the fourth is at Potash 

Sulphur Springs, Garland County. In addition there are hundreds 

of dikes of igneous rock scattered here and there over much of the 

east half of the Ouachita Mountain region. Concerning these dikes 

Williams 81 says:

Outside of these four typical regions there are many dikes of igneous rock 

which as far as their petrographic characteristics are concerned might be 

associated as well with one group [region] as with another and which are, as a 

matter of fact, probably directly connected with none of them, although formed 

from the same magma from which they all derived their material.

The rocks in the dikes include tinguaite, fourchite, ouachitite, and 

monchiquite. Of these the monchiquite is more closely related in 

composition to the peridotite in the Caddo Gap quadrangle than any 

other, for it is composed mainly of altered olivine and augite and at 

some places contains much biotite.

AGE OF THE; PERIDOTITE

The peridotite of each of the several occurrences is similar to that 

of the others, and although there is no surface connection between 

these occurrences, the similarity of the rocks makes it seem very 

probable that the rocks are of.common origin and are connected 

beneath the surface.

The three types of peridotite were apparently formed by three 

distinct volcanic outbursts, but they are so closely related that they 

probably represent successive stages in a single period of volcanic

activity. Present evidence indicates the igneous history of the region 

set forth below.

First the intrusive peridotite was injected upward into the Carboniferous and Lower Cretaceous rocks. Then volcanic explosions 

broke up into small fragments not only much of the intrusive peridotite but also some of the shale and sandstone of Carboniferous age. 

In the Prairie Creek peridotite area the fragments were apparently 

ejected into the air and then deposited ,in inclined layers, which have 

since been hardened, becoming a breccia.

A second group of explosions probably took place, forming the 

tuff and closely associated fine-grained breccia of the Prairie Creek 

area. The distribution of these rocks and their relation to the intrusive peridotite and to the volcanic breccia apparently indicate that 

they are the younger.

81 Op. cit, pp. 2-3.
IGNEOUS ROCKS 115

The peridotite is younger than the Trinity formation, of Lower 

Cretaceous age, as is shown (1) by.the high dip of the contacts between the peridotite and the nearly horizontal beds of the Trinity, 

(2) by the metamorphism of the clay of the Trinity adjacent to its 

contact with the peridotite, and (3) by the occurrence in the peridotite of fragments of clay and pebbles derived from the Trinity.

The peridotite is of the same age as or older than the Tokio formation of Upper Cretaceous age. This is shown by the fact that the 

loAver beds of the Tokio on the Kiley place and on the Twin Knobs, 

near Murfreesboro, contain altered serpentine grains and fragments 

of peridotite. Although these grains and fragments were waterlaid, there is a probability that they were ejected as fragmental material from one or more near-by vents rather than washed by streams

from peridotite exposures. The belief that the peridotite is not

younger than the Tokio is supported by the fact that the Tokio rests 

upon the peridotite at the American mine and at the Black Lick.

From the foregoing facts it must be concluded that the peridotite 

is younger than the Trinity formation, of Lower Cretaceous age, and 

is not younger than the Tokio formation, of Upper Cretaceous age. 

The volcanic activity that produced the peridotite probably accompanied the down warping of the Mississippi embayment early in the 

Upper Cretaceous epoch.

COMPARISON OF ARKANSAS AND SOUTH AFRICAN ROCKS

The peridotite of Arkansas is generally believed to be similar in 

character and mode of occurrence to that of South Africa, and the 

exact points of similarity are here recorded. Wagner,82 who has carefully studied the South African diamond deposits, says of them:

The pipes represent deeply eroded, funnel-shaped volcanic necks of the 

Maar type, which appear to have been formed by the violent explosive.liberation at the earth's surface of highly compressed vapors and gases, emanating 

from a deep-seated, ultrabasic magma. They are occupied, as a rule, by 

nonvolcanic detritus derived from the shattering and comminution of the 

rocks pierced by the explosions, by fragmentary material derived from trituration of kimberlite [peridotite], and at greater depths by solid plugs of the 

later rock.

Dealing first with the relationship of pipes to fissures, we have learned that 

the magma in its ascent appears invariably to have been guided to within a 

greater or less distance of the original surface by planes of structural weakness in the earth's crust. * * * The earliest eruptions appear to have been 

in the nature of mighty explosions, which resulted in blowing out of funnelshaped apertures. The bulk of the material forcibly ejected during these outbursts no doubt fell back into the vents, which at one stage of their history 

may thus have been more or less completely occupied by nonvolcanic detritus.

82 Wagner, P. A., The Diamond Fields of Southern Africa, 1914.
116 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

The relief of pressure occasioned by these earlier explosions must be assumed 

to have led to the ascent of the magma into the pipes, where it appears, as a 

rule, to have given rise, by successive eruptions, to a number of distinct 

columns of kimberlite [peridotite] and kimberlite tuff.

The material that occupies the vents Wagner describes as follows:

It has been pointed out that in so far as the pipe filling is concerned, the 

rocks pierced by the explosions, the kimberlite magma, and . the atmosphere 

have all contributed.

We may divide * * * the foreign matter of the pipes into three principal 

groups rock fragments derived from the adjacent pipe walls; xenoliths [included fragments] of rock which have been brought up from below: masses 

of rock which, to attain the position in which we now find them, must have 

fallen into the pipes from above.

The pipe rock proper consists of kimberlite and of material derived from 

its brecciation, comminution, and decomposition.

The microscope reveals the fact that among the products comprehended 

under the general term of blue ground three main varieties may be distinguished. These are the true kimberlite tuff or kimberlite breccia, injection 

breccia, and decomposed kimberlite. * * * As greater depths are attained 

in the mines the products we have hitherto been dealing with, as one would 

naturally expect, are replaced in increasing measure by " hardebank," or kimberlite, the parent rock, to the trituration and decomposition of which they 

owe their origin.

Wagner divides the diamond-bearing rocks of South Africa into 

two types, both of which occur as intrusives and as volcanic breccias. 

One of these is a " basaltic kimberlite," rich in olivine and poor in 

mica, and the other is a " mica peridotite." Both types are diamond 

bearing in South Africa, but the first has produced most of the 

diamonds.

The quotations and abstracts given above, which outline very 

briefly the type of eruption and describe the diamond-bearing rocks

of South Africa, serve as a basis for comparison with the diamondbearing rocks of Arkansas. In South Africa work has proceeded to 

great depths 3,601 feet in the Kimberley mine and the geologic 

relations are known in considerable detail, whereas in Arkansas only 

the surface of the ground has been scratched. Nevertheless rather 

striking points of similarity between the diamond-bearing rocks of 

South Africa and of Arkansas are evident.

The violence of the volcanic explosions by which the South 

African vents were produced and the extent to which the kimberlite 

and country rock were shattered and mixed together in the vents 

have been emphasized. In Arkansas the peridotite was evidently 

much shattered and the explosive violence brought to the surface 

Paleozoic rocks that lay far beneath the surface. Injection breccias 

that are composed of shattered country rock mixed with a small 

proportion of volcanic material and that have the characteristics of 

dikes have been identified in both areas.
STBUCTURE 117

In many of the South African vents recurring volcanic activity 

produced compound pipes that are formed of slightly different rocks 

and that even bear diamonds of dissimilar character. Petrographic 

studies have shown that in Arkansas there are at least three types 

of rock, only one of which carries diamonds in considerable quantity.

STRUCTURE 

GENERAL FEATURES

The sedimentary rocks of the Caddo Gap and De Queen quadrangles^ originally lay nearly horizontal. The Cretaceous strata are 

still nearly horizontal, but they have been tilted so that they have a 

low southward dip, and the Paleozoic strata are inclined at high 

angles, so that their edges appear at the surface.

When the Paleozoic rocks are crossed from north to south they are 

found to lie in a series of anticlines and synclines, and in a few places 

they have suffered displacement by faults. The greater part of their 

folding and faulting took place near the middle of the Pennsylvanian 

epoch, although slight warping occurred at a much earlier time.

To aid in understanding the structure of the quadrangle the structure sections in Plate 15 are introduced. These sections represent the 

structure as it is inferred from the position of the beds observed at 

the surface, but they are on too small a scale to show all the minute 

structural details.

STRUCTURE OF THE PALEOZOIC ROCKS 

FOLDING

The Caddo Gap and De Qneen quadrangles contain two areas 

where the oldest rocks have been uplifted through folding and now 

stand as high as the youngest. One of these areas includes the 

mountainous portions of the Caddo Gap quadrangle and the northeast corner of the De Queen quadrangle. It is a part of the west end 

of the Ouachita anticline, which is the most prominent fold of the 

Ouachita region in Arkansas. The other area includes the Cross 

Mountains, in the western part of the De Queen quadrangle. It is 

the east end of the Cross Mountains anticline, which is one of the 

most prominent folds of the Ouachita region in Oklahoma.

The large composite folds are essentially anticlinoria, and some of 

their larger subdivisions can be followed for long distances; but the 

single folds, which are narrow and overlap one another lengthwise, 

can be traced only a few miles along their axes. They all have the 

same direction as that of the ridges and therefore bear a close relation to the topography, for outcropping edges of the hard strata 

6242 29 9
118 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

upturned on the folds have formed the ridges and the softer intervening strata underlie the valleys. Their general trend does not 

depart far from west, but it is north of west in the Ouachita anticline, west in the Cross Mountains anticline, and south of west in the 

Athens Plateau. The westward divergence of the folds of the Athens 

Plateau from those of the Ouachita anticline is attributed to the eastward plunging of the Cross Mountains anticline in the De Queen 

quadrangle. Many adjacent folds are of nearly the same height, and 

the same beds are repeated many times at the surface. The dip gradually changes in steepness from place to place along the strike, and on 

some of the folds it even changes in direction within a mile. These 

changes may take place where a single fold breaks up into two folds, 

or where a symmetrical fold is closely compressed so that the strata 

are parallel. Two structure sections of the same mountain or valley 

only a mile apart might therefore be very different. Scarcely any 

two ridges are alike in structure, and some of them, especially many 

high peaks, are composed of two or three anticlines with their intervening synclines. The sides of most folds have been compressed 

until they are parallel, the rocks on one side having been turned 

through an angle exceeding 90°, so that the beds on both sides of 

the crest dip in the same direction. The dips of the overturned 

rocks are in places as low as 40°. This shows that the rocks in those 

places have been turned through an angle of 140°. The rocks have 

been overturned toward the north in some folds and toward the 

south in others. (See pis. 15 and 16.) This overturning of the rocks 

in two directions has produced fan-shaped folds at a few places. 

A compound fan-shaped fold in the De Queen quadrangle is illustrated by Plate 16, F, and a number of folds with a fan-shaped arrangement are illustrated by Figure 6. In most places the folds are 

smallest, most numerous, and most closely squeezed in the shale and 

thin-bedded sandstone and chert. Joints in several sets and slickensides are common in all the rocks but are most numerous in those just 

named.

OUACHITA ANTICLINE

The part of the Ouachita anticline that is situated in the Caddo 

Gap^and De Queen quadrangles includes the Caddo, Crystal, and 

Cossatot Mountains and the Caddo and Mazarn Basins. In these 

quadrangles it is divided longitudinally into two anticlines by the 

Mazarn syncline, much of which extends in a general north of west 

direction along the valley of South Fork in the Caddo Gap quadrangle and along Mine Creek in the De Queen quadrangle. The anticline lying north of this syncline is the Crystal Mountain anticline, 

and that on the south is the Cossatot anticline.
STRUCTURE 119

Crystal Mountain anticline. The Crystal Mountain anticline contains the area of greatest uplift in the quadrangles. The highest 

part lies along the northern edge of the Caddo Gap quadrangle, 

where the following formations not elsewhere revealed are exposed: 

(Jollier shale, Crystal Mountain sandstone, Mazarn shale, Blakely 

sandstone, and Womble shale. These shales and the Bigfork chert 

are so intensely crumpled that the details of their structure can not 

be determined, so that it has been necessary to generalize their structure as shown on Plate 15, but many of the smaller as well as all 

the larger folds of the other formations are determinable. The 

strata in most places are inclined at angles of 40° or more from the 

horizontal. Most of the folds are parallel and straight, trend north 

of west, and overlap one another lengthwise. The folds are rarely

symmetrical; as a rule either one limb is much steeper than the other

or both limbs, being closely compressed, dip in the same direction. 

The axial planes of most of the folds dip to the north, and therefore 

the south limbs of those anticlines that are not overturned have 

steeper dips than the north limbs, and both limbs of the overturned 

folds dip to the north. In some places, especially in the vicinity of 

High Point, in the De Queen quadrangle, the reverse relation is 

noted. (See pi. 16, E, and fig. 6.) On account of this overturning 

in two directions a fan-shaped fold has been formed at one place 

in the De Queen quadrangle. (See pi. 16, F.) The overthrusting in 

the process of folding was therefore mainly from the north but 

partly from the south. Some of the anticlines are broken by .thrust 

faults.

The Crystal Mountains comprise an area of short branching and 

interlocking anticlines and synclines. The ridges, most of which are 

produced by the hard Crystal Mountain sandstone, show from place 

to place an anticlinal, a synclinal, or a monoclinal structure, and the 

valleys, which are occupied by the Collier and Mazarn shales, reveal 

much the same variety. The ridge of Blakely sandstone that runs 

east from Womble to the east border of the Caddo Gap quadrangle 

is a monocline, and much of it is fairly straight, but its structure 

near Plata is affected by short wrinkles that have made the ridge 

crooked and produced small projecting1 spurs.

The part of the Crystal Mountain anticline that lies in the northeast corner of the De Queen quadrangle and the adjoining part of 

the Caddo Gap quadrangle is a closely corrugated belt composed 

of folds of nearly equal size, and in most of the folds the outcrops of 

the same formations are repeated. The Missouri Mountain slate and 

Arkansas novaculite are commonly exposed in the anticlines, most of 

which are ridges, and the Stanley shale is exposed in the synclines, 

most of which are valleys. The structure of the ridges varies from
PLATE 16

A, B, C, and D. Sections through Whiskey Peak, Bast Hanna Mountain, Katy 

Mountain, and Raspberry Peak, illustrating closely compressed folds 

overturned toward the south.

E. Section through High Point, illustrating closely compressed folds overturned 

toward the north.

F. Section through two ridges 1 mile east of Spring Valley School and north 

of Mine Creek, in the De Queen quadrangle, illustrating a fan-shaped 

double anticline, which is broken at the right by a thrust fault.

O. Section through Brier Creek Mountain, half a mile west of Little Missouri 

River, showing the formation of a thrust fault by the breaking of an 

overturned anticline.

H. Section through Brier Creek Mountain 1% miles west of Little Missouri

River,' showing displacement along the fault greater than that in

section G. 

120
U. S. GEOLOGICAL SURVEY BULLETIN 803 PLATE 16

\ C

Katy Mtn.\ ,'

Sm Sb Ope Obf Ope Sb Ope Sb Ope Obf S

SECTIONS THROUGH SEVERAL MOUNTAINS IN THE DE QUEEN AND CADDO 

GAP QUADRANGLES, ARKANSAS AND OKLAHOMA, ILLUSTRATING THEIR COMPLICATED STRUCTURE

Cs, Stanley shale; Da, Arkansas novaculite; Sm, Missouri Mountain slate; Sb, Blaylock sandstone; 

Ope, Polk Creek shale; Obf, Bigfork chert
STRUCTURE 121

place to place. Some ridges or parts of ridges are composed of 

single anticlines, but others for example, High Point (pi. 16, E), 

in the De Queen quadrangle, and the east end of Statehouse Mountain, in the Caddo Gap quadrangle are made1 up of two anticlines 

with the intervening syncline. The east end of Fork Mountain, in the 

Caddo Gap quadrangle, is composed of two synclines and the intervening anticline. Not all parts of the ridges, however, are anticlinal; 

some are monoclinal, such as the Missouri Mountains between Slatington and Fork Mountain, and others are synclinal.

In the vicinity of Caddo Gap the folds along the south side of the 

Crystal Mountain anticline plunge toward the east at comparatively 

high angles, so that the oldest rocks are exposed on the north and 

west and the youngest on the south and east. Here the plunging anticlines and synclines interlock in such a way that the truncated upturned edges of the strata zigzag across the country. The best 

example of th,is type of structure in the Ouachita Mountain region 

is in the Zigzag Mountains at and near Hot Springs, Ark.

Cossatot anticline. The Cossatot anticline consists of a large 

number of minor anticlines with their complementary synclines and 

lies almost entirely in these two quadrangles. The axis of greatest 

uplift passes just north of Prior, Blaylock, Brushheap, and Easpberry Mountains, in the Caddo Gap quandrangle, and along the 

valley of Sugar Creek and by Shady post office, in the De Queen 

quadrangle, and hence runs along or near the central part of the 

anticline. The oldest formations exposed along this axis are the 

Bigfork chert and the Polk Creek shale, and the other formations, 

owing to their close folding, are repeatedly exposed in narrow bands 

on the north and south. The single folds, as well as the major fold 

which they compose, trend north of west, parallel with the Crystal 

Mountain anticline. The single folds are of about equal height, are 

only a few miles long, and are all less than a mile wide. They overlap one another lengthwise and plunge at their ends, some to the east 

and some to the west. Reference to Plates 15 and 16 will show that 

most of the folds are not symmetrical, but that many of them are 

overturned, some to the north and some to the south, and that others, 

although not overturned, have steeper dips on one side than on the 

other.

The overturning to the north prevails near the east and west ends 

of the anticline, and the overturning to the south in the middle portion. A structure section (fig. 6) through the western part of the 

Cossatot anticline and the adjoining part of the Crystal Mountain 

anticline shows a fan-shaped arrangement of the folds. The strata 

in most places in the Cossatot anticline stand nearly on edge, dipping 

50° or more from the horizontal. A line of faulting runs along the
122 D*J QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

north side of the anticline. The ridges are all produced by the 

Arkansas novaculite, and the structure of many of them is simple 

that is, a ridge or some part of one may be monoclinal, synclinal,

or anticlinal. Many others, however, consist of two or more folds 

and therefore have a complex structure. A north-south section (fig. 

6) passing through the summit of 

West Hanna Mountain shows that 

this mountain is composed of three 

anticlines and that one of the intervening synclines forms its summit. 

A similar section through East 

Hanna Mountain (pi. 16, B) shows 

three anticlines and the two intervening synclines. A northeast section through the highest part of 

Eagle Mountain (fig. 6) reveals a 

syncline at the summit and a 

faulted anticline on the northeast 

slope. Katy Mountain (pi. 16, C) 

and Tall Peak are each composed 

of two anticlines and the intervening syncline; Nichols Mountain 

is made up of a syncline and an 

anticline; and Raspberry Peak (pi. 

16, D] of two anticlines and two 

synclines. The summits of these

mountains and many others have 

a synclinal structure, and because 

of this they form some of the 

highest points in the quadrangles. 

Muzwn syncline. The Mazarn 

syncline extends in a north of west 

direction along the valley of South 

Fork in the Caddo Gap quadrangle 

and that of Mine Creek in the 

De Queen quadrangle. It is widest 

on the east border of the Caddo 

Gap quadrangle and is narrowest 

in the vicinity of McKinley and Lost Mountains, where it is no 

wider than the single synclines in the anticlinal areas on either side 

and where it is crossed by the faulted anticline passing through 

Lost Mountain and Hurricane Knob, but farther west along Mine
STRUCTURE 123

Creek and the head of Cossatot River, in the De Queen quadrangle, it 

is fairly distinct. Along its edges are narrow synclines which reach 

into the anticlinal areas on each side and interlock with the numerous 

anticlines that plunge beneath the Mazarn syncline. A narrow syncline which is occupied by the Jackfork sandstone lies on the east 

boundary of the Caddo Gap quadrangle. In most parts of the 

Mazarn syncline the detailed structure could be worked out with 

extreme difficulty, if at all, because there are here no distinctive beds 

in the Stanley shale, which is the surface formation over most of the 

syncline, and because the Stanley, having relatively low rigidity, has 

been thrown into small, closely compressed folds or wrinkles instead 

of the larger ones found in the more competent formations such as the 

Arkansas novaculite.

CROSS MOUNTAINS ANTICLINE

The Cross Mountains anticline, which is one of the major folds of 

the Ouachita region of Oklahoma,83 extends eastward to the middle 

of the De Queen quadrangle. This composite anticline finds expression in the Cross Mountains, whose easternmost anticlinal ridges are 

separated from the Cossatot Mountains by a narrow synclinal trough, 

which connects the Athens Plateau with the Cove Basin. The single 

folds have a general eastward trend. All are of nearly the same 

height and reveal the same formations the Stanley shale and Arkansas novaculite but in addition to these rocks the anticlines near Bog 

Springs and Hatton bring to the surface the Blaylock sandstone and 

the Missouri Mountain slate. As a rule, the folds are asymmetric. 

Those anticlines that are not overturned have steeper dips on the south 

limb than on the north and those that are overturned have northward 

dips on both the north and south limbs. Whisky Peak, the principal 

mountain of the group in the De Queen quadrangle, consists of three 

anticlines with the intervening synclines, one of which occupies the 

summit. (See pi. 16, A.)

ATHENS PLATEAU

The general structure of the Athens Plateau is that of a southward-sloping monocline corrugated with many minor folds. These 

folds are nearly parallel and have a general south of west trend. 

Toward the west their trend and that of the Ouachita anticline 

diverge and they pass on both sides of the eastward-plunging Cross 

Mountains anticline. The most conspicuous and easily distinguishable folds are formed by the Jackfork sandstone and the Atoka 

formation. Although each of these formations is about 6,000 feet

83 Honess, C. W., Geology of the Southern Ouachita Mountains of Oklahoma: Oklahoma 

Geol. Survey Bull. 32, pp. 236-240, 1923.
124 DE QUEEN AND CADDO GAP QUADRANGLES, .ARKANSAS

thick, the beds stand at steep angles, having dips that commonly 

exceed 50°, and in some places they are overturned. 'The usual 

direction of the overturning is from the south.

Although the Stanley shale, which is also exposed on this plateau, 

has a thickness of 6,000 feet, it is folded many times and doubtless 

much faulted and overturned in its wide belts of outcrop, but the lack 

of distinctive beds, except the Hatton tuff lentil and the associated 

beds of tuff, makes the determination of the folds nearly impossible. 

Although the dips and strikes differ somewhat, most of the strikes 

have an eastward trend, and most of the dips are 40° or more.

COVE BASIN

The Stanley shale, which is the prevailing surface formation of the 

Cove Basin, is compressed into many narrow, steep-sided folds, but 

in most localities in this basin, as on the Athens Plateau, only the 

general structural features can be determined. The folds trend in 

general eastward, but next to the Cossatot Mountains they trend south 

of east. The principal feature is an anticline, whose axis passes eastward one-tenth of a mile south of the depot at Cove. Two or more 

beds of tuff that occur near the base of the Stanley are exposed on 

the anticline.

FAULTING

Faults are common, though less numerous than might be expected in 

strata that have been so closely compressed as these. The number of 

the faults has been limited by the great predominance of thin-bedded 

strata over massive, rigid beds like the Crystal Mountain sandstone, 

Arkansas novaculite, and Jackf ork sandstone, in consequence of which 

the beds as a whole bent instead of breaking under stress. About 

30 faults have been mapped in the two quadrangles, and others may 

be detected in future work. The faults were produced by the breaking and overthrusting of strata in closely compressed anticlines. 

(See pi. 16, G and H.) An anticline at Caddo Gap has been broken 

by two thrust faults. (See pi. 7, A.} So far as observed all the 

faults are thrust faults except one small normal fault in the SW. a/4 

sec. 31, T. 3 S., R. 26 W. The direction of the faults, therefore, is in 

the main east, or parallel with the ridges. The longest ones do not 

exceed 12 miles in length and most of them are much shorter. The 

dip of all the fault planes is high; some of them dip south and some 

north. The dislocation ranges, even along a single fault, from a 

few feet to a few thousand feet or more, but only a minimum measure 

is obtainable anywhere.

As may be seen, by reference to Plate 3, many of the faults occur 

near the boundary between the Mazarn syncline and the Cossatot 

anticline. These faults, in fact, form the principal line of faulting
STRUCTURE 125

in the quadrangles, and the line extends from the valley .of Sugar 

Creek in the De Queen quadrangle approximately eastward, passing 

south of Fancy Hill and along the valley of South Fork in the 

Caddo Gap quadrangle, and apparently terminates near Caddo Kiver. 

From Little Missouri Kiver westward the line consists of a single 

fault, but in the eastern part of range 27 it comprises three and along 

the base of Bearden, Tweedle, and Keynolds Mountains. there are 

two long and two short, nearly parallel faults. The overthrust of 

these faults is from the south. Their planes as well as those of most 

other faults in the quadrangles dip in the same direction as the 

broken strata.

A cross fault, having a northwesterly trend and with its upthrow 

on the northeast side, is situated on the border of the Caddo Gap 

quadrangle east of Kirby. It truncates the east end of a syncline

containing the Jackfork sandstone and.the overlying Atoka formation, and the Stanley shale is brought up even with the Atoka, making 

a vertical dislocation of at least 5,000 to 6,600 feet, which is the 

range of thickness of the Jackfork in the Caddo Gap quadrangle. 

How much greater the displacement is can not be determined, but 

it may amount to fully 10,000 feet. Although the hade was not 

observed, the fault is thought to belong to the thrust variety because 

of the almost exclusive occurrence of this type in most of the Ouachita 

region. Much of the displacement may have been horizontal that is, 

in a southeastward direction on the northeast side of the fault and in 

a northwestward direction on the southwest side. Detailed mapping 

in the adjoining area on the east will doubtless yield further information concerning this peculiar fault.

METAMORPHISM

Mechanical and chemical action which accompanied the folding of 

the beds in this region has produced changes in many rocks. The 

alteration by these two agencies has perhaps been most effective upon 

the shale, changing some of it to slate. The beds that have been 

most affected are the Mazarn, Womble, and Polk Creek shales, the 

Missouri Mountain slate, the shaly part of the Arkansas novaculite, 

and the base of the Stanley shale, although at most places these have 

been only slightly altered. This production of slate has consisted in 

the flattening of the mineral particles of the shale, the rotation of 

their axes to a position at right angles to the pressure, and the formation of new minerals with their major axes lying in the same direction, thereby producing slaty cleavage. This cleavage is usually 

at an angle to the bedding. The sandstone that is not calcareous has 

become more or less quartzitic. Examples of this alteration occur in 

the Crystal Mountain and Blakely sandstones. The Jackfork sand-
126 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

stone and the sandstone of the Stanley shale are quartzitic, but on 

long exposure to weathering they lose much of their siliceous cement.

STRUCTURE OF THE CRETACEOUS ROCKS

The Trinity and succeeding formations probably have the same 

attitude now as when they were deposited, excep.t that they have been 

slightly tilted toward the south, the oldest formations having been 

tilted most. (See pi. 15 and figs. 8 and 9.) The strike of the Trinity 

and Woodbine formations is east or nearly east, but that of the 

Brownstown marl, Tokio formation, and other formations that are 

exposed east and south of the quadrangles is north of east.

The southward dip of the floor or base of the Cretaceous just north 

of Center Point is more .than 100 feet to the mile, as is shown by a 

well 2 miles north of that place, which did not reach the base of the 

Cretaceous at a depth of 500 feet. A southward dip of more than 100 

feet to the mile also is shown near De Queen, as the ice-factory well 

249 feet deep at that place did not reach the base of the Cretaceous. 

The dip of the base of the Cretaceous is about 100 feet to the mile 

from the north edge of the Gulf Coastal Plain southward to Nashville, Ark., a distance of 15 miles. A well at that city reached the 

Cretaceous floor at a depth of about 1,250 feet.

On the north edge of the Gulf Coastal Plain in the Caddo Gap 

and De Queen quadrangles the Cretaceous floor emerges from beneath the Cretaceous cover at about 350 feet above sea level along the 

principal streams, and it gradually rises toward the north, the highest remnants still capped by the Cretaceous attaining an altitude 

of 800 feet above sea level. The dip of the floor where the Cretaceous 

cover is thus partly removed ranges from about 60 to 100 feet to the 

mile, but the usual dip is about 80 feet to the mile.

The Cretaceous strata, as noted in the foregoing paragraphs, do 

not everywhere have a uniform dip to the south. Although from this 

fact they are seen to be slightly warped, no folds in the Caddo Gap 

and De Queen quadrangles are known to be developed sufficiently to 

be called anticlines or synclines.

GEOLOGIC HISTORY

The geologic history of the Caddo Gap and De Queen quadrangles 

is recorded in their surface features and in the underlying rocks. 

The history interpreted from the topographic features probably is 

the less complete, because its records have been largely destroyed 

by erosion. Although the succession of events as recorded in the 

quadrangles is imperfect, many facts may be inferred from studies 

in other parts of the Ouachita Mountain region and in adjoining
GEOLOGIC HISTORY 127

provinces, for the same processes that operated in the area comprised 

in the quadrangles also affected similarly an extensive region 

around it.

CAMBRIAN PERIOD

Collier deposition. The thickness of the Collier shale is not 

known, for its base is nowhere exposed, but at least a few hundred 

feet of it is visible between the north line of the Caddo Gap quadrangle and Mount Ida, in Montgomery County. Its black color and 

argillaceous nature show that it was derived from mud containing 

carbonaceous matter, and the limestone beds within it indicate that 

it was laid down close to a shore and consequently is a shallowwater formation. If it was thus laid down, the land area that supplied it was low, and the streams of the area were unable to carry

coarse material. The purity of the limestone beds indicates that 

there were times in which sedimentation almost ceased and in consequence the sea cleared, so that the calcareous material was deposited 

without much mud. Marine life at this time was meager, if we 

may judge from the apparent absence of fossils from both the shale 

and the limestone.

Deposition was halted by an emergence in the present Crystal 

Mountain area, and also in McCurtain County, Okla.,84 and a period 

of erosion was the result. The known extent of the stratigraphic 

break caused by this emergence is thus considerable. This together 

with the fact that it occurs in rocks many hundred feet below those 

known by their fossils to be of Lower Ordovician age, is apparently 

sufficient reason for believing that the Collier shale belongs to the 

Cambrian system.

ORDOVICIAN ( ?) PERIOD

Crystal Moimtain deposition. After erosion had attacked the 

Collier shale for a period which may have been long or short the 

area included in west-central Arkansas and southeastern Oklahoma 

was again covered by the sea, and the material of the Crystal Mountain sandstone was spread upon it. Quartz, chert, and limestone 

pebbles, which were obviously derived from beds in the Collier, 

were deposited along the shore as the sea crept upon the land, 

and these pebbles, with other material, formed conglomerate. As 

the water deepened deposition became restricted to sand, which in 

places accumulated to a depth of 850 feet. This is rather coarse 

quartz sand, much of which is well rounded, and at the time of its

84 Honess, C. W., Geology of the Southern Ouachita Mountains, Okla.: Oklahoma Geol. 

Survey Bull. 32, pp. 46-47, 1923.
128 EE; QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

deposition it formed a clean sandy beach and ocean bed. It contains 

no fossils, probably because the rapid piling up and shifting of the 

sand prevented colonies of marine life from becoming established. 

As time went on the material brought into the sea became gradually 

finer, and eventually the sea floor and probably the beach became 

muddy, thus bringing in Mazarn deposition.

ORDOVICIAN PERIOD

Ma&arn, Blakely^ and Wonibl& deposition. The sea, which gradually became muddy at the end of Crystal Mountain time, continued 

so throughout most of Mazarn, BJakely, and Womble time, when 

mud was widely distributed in the present Ouachita Mountain region 

both in Oklahoma and Arkansas. The land area was probably low; 

it was also presumably wet in parts, and this condition permitted a 

reduction of the iron oxide in the residual mantle. Greenish mud 

derived from this mantle was laid down in thin layers alternating 

with layers that had been blackened by carbonaceous matter. These 

conditions prevailed until 1,000 feet of mud, which later formed the 

Mazarn shale, had accumulated, and some sand had been intermittently brought to the sea and put down in thin layers. Next at 

least a part of the region was uplifted and eroded.

Blakely time began with an advance of the sea over the eroded 

areas. Pebbles were laid down here and there in the Hot Springs 

district, but later sand and mud were deposited in alternate layers 

until in places a thickness of 400 feet accumulated. This sedimentation in the Hot Springs district was twice interrupted by extreme 

shallowing of the water if not by changes of the area to land, as is 

shown by beds of conglomerate above the base of the sandstone. 

None of these conglomerates were observed in the Caddo Gap quadrangle. The distribution of the sand was not general, for west of 

Womble it is only locally represented, and it is absent in the vicinity 

of Mount Ida, on the north side of the Ouachita anticline. During 

Womble time mud and a very small quantity of sand accumulated 

until a thickness ranging from 250 to 1,000 feet was put down. 

This increase of mud and decrease of sand after Blakely time may 

have resulted from a subsidence of the supplying land area.

The sea was probably shallow during the deposition of the 2,400 

feet of mud and sand composing the three formations just described. 

There must have been, therefore, a practically continuous subsidence 

of the sea bottom while these sediments were accumulating.

Marine life was meager during Mazarn and Blakely time but was 

more abundant during Womble time. It consisted chiefly of graptolites, an extinct order of Hydrozoa, which while alive floated 

in the water. After they died their delicate remains sank to the
bottom of the sea and were there buried in the mud that was being 

brought from the land. They have doubtless supplied some of the 

carbonaceous matter of the black shale to which the mud has sincehardened.

Although the water was muddy and received some sand during 

Mazarn, Blakely, and Womble time, it became clear enough now 

and then to permit limestone to be formed. But during a largepart of this time limestone was being formed on the north in the 

Ozark region, on the west in the Arbuckle Mountains of Oklahoma, 

and on the east in the southern Appalachian region. This difference 

in the character of the sediments on these three sides and the small 

distribution of the Blakely sandstone, which is exposed only in the 

southern part of the Ouachita Mountains, strongly indicate that the

clastic materials of these formations came from the south.

Bigfork deposition. After the Womble deposition was completedr 

layers of silica and thinner layers of mud, aggregating 700 feet in 

thickness, were put down in probably all the Ouachita Mountain 

region and later formed chert and shale, respectively. To the formation thus produced the name Bigfork chert has been applied. Thedeposition of chert and shale in alternating layers during Bigfork 

time and that of limestone and shale of the Hermitage formation of 

Tennessee suggest that the Bigfork and the Hermitage, both of 

Trenton (Middle Ordovician) age, were formed contemporaneously. 

The water, to judge from the small amount of shale in the formation,, 

was at first relatively clear, but late in Bigfork time much mud 

brought from the land area was intermittently deposited with the 

silica forming the chert. Furthermore, the water was not of great 

depth, as is indicated by the ripple-marked surface of the sandstone. 

In the Bigfork, as in the Womble shale beneath, great number's of 

graptolite remains were buried in the mud layers and are now well 

preserved in the shale. Evidently conditions at this time were not 

favorable for other kinds of marine life, as only a few brachiopods, 

bryozoans, and trilobites have been found in the Bigfork chert of 

Arkansas and a few sponge species in this formation in Oklahoma. 

The presence of the spicules suggests that at least a part of the silica 

which produced the chert was derived from such remains, but whether 

it was largely deposited by organic means or by chemical precipitation 

alone or by both processes is not known.

Polk Creek deposition. Bigfork time was ended and Polk Creek 

time was begun by an increased muddiness of the sea. Black mud 

was rather uniformly spread over much if not all of the Ouachita 

Mountain region. Great numbers of graptolite remains were embedded in the soft mud, and many of them have been well preserved, 

though the mud has been changed to shale and in places to slate.
130 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

SILURIAN PERIOD

Blaylock deposition. After Polk Creek time the land area which, 

it is believed, existed on the south was probably elevated sufficiently 

to invigorate the streams, so that in addition to a good deal of mud 

they now carried to the sea large quantities of sand. Later the sand 

and mud hardened into sandstone and shale, respectively, and to these 

beds the name Blaylock sandstone is applied. Graptolites comparable to species found in Great Britain rather than any now known 

elsewhere in America lived at this time, but their remains are scarce, 

only a single collection having been made.

A conglomerate of local distribution in the De Queen quadrangle 

indicates that land was not far distant, if indeed it did not exist in 

the quadrangle prior to Blaylock time/ That sediment at this time 

was put down in a rapidly subsiding trough is suggested by the pronounced thickening of the formation southward, the increase amounting to at least 550 feet within a few miles from the thin edge of the 

formation, in the Hot Springs district, and reaching 1,500 feet 

within a like distance, in the Caddo Gap quadrangle. This depositional trough, though it exists only on the south side of the Ouachita Mountain region, has a considerable length extending from a 

point near Malvern, in central Arkansas, westward nearly to 

Wright City, in southeastern Oklahoma. The northward thinning 

of the sandstone may be due partly to erosion, as is indicated by the 

local occurrence of a conglomerate at the base of the overlapping 

Missouri Mountain slate. If the thinning out of the sandstone is 

due entirely to erosion at least 1,500 feet of material has been removed from the northern part of the present Ouachita region, and it

would be expected that the underlying Polk Creek shale would also 

have been removed from large areas at the same time the Blaylock 

was being removed. But the Polk Creek shale is generally present 

in the region north of that in which the Blaylock sandstone occurs, 

and its thickness there is much the same as it is in places where it 

underlies the Blaylock. The conclusions regarding the Blaylock 

are that it was deposited in a minor east-west trough on the south 

side of the Ouachita geosyncline, that the northward thinning of the 

formation can be attributed in only a very small part to erosion, and 

that the land-derived sediments for it came from the south.

Blaylock sand deposition was ended by an emergence of parts of 

the region, including at least parts of the quadrangles herein described, but this emergence probably was not general, else more than 

local evidences of an erosion period would be present. The succeeding Missouri Mountain slate is in places like some of the shale in 

the Blaylock, and the apparent absence of any distinct boundary
GEOLOGIC HISTORY 131

between the two shows that sedimentation in such places may not 

have been interrupted by land conditions.

Missouri Mountain deposition. After Blaylock time the sea deepened, trangressed over those parts of the area that had been dry land, 

and in places put down a layer of coarse conglomerate that constitutes the initial deposit of the Missouri Mountain slate. Next fine 

red clay and in some places black clay were laid down throughout 

the Ouachita region. The prevailing absence of coarse material, 

such as subsequently becomes sandstone or conglomerate, suggests 

that the bordering land was low. The common red color of the shale 

indicates that the surface of this land had been deeply weathered 

after long exposure and that the mantle of soil had been colored red 

by the long-continued oxidation of its iron content. The removal 

of this material from the land area was probably the result of 

invigorated erosion.

DEVONIAN PERIOD

Arkansas novacuUte deposition. The next epoch, which was one 

of sedimentation .throughout the Ouachita region, was characterized 

by the deposition, through organisms or chemical precipitation or 

both, of silica and a little calcareous material. The first deposit in a 

few places is a conglomerate, consisting of rounded quartz and 

novaculite pebbles embedded in a novaculite matrix. The local 

occurrence of the conglomerate suggests that little of the region was 

above water. As the water deepened silica and very meager amounts 

of other materials, later forming massive white novaculite, accumulated and in places reached a thickness of 425 feet. That the land 

during the accumulation of this vast amount of siliceous material 

was low or possibly remote is attested by the delivery of only a very 

small quantity of detrital material, which consisted wholly of 

rounded quartz grains and mica; and that the sea was relatively 

shallow is shown by the presence of ripple marks in the heavy 

bedded novaculite.

This part of the novaculite is of Middle Devonian age. Next mud, 

usually black, was put down in thin layers intermittently with those 

of the siliceous material, but later the silceous material, some calcium 

carbonate, and a very small quantity of mud were deposited. The 

middle and upper divisions of the Arkansas novaculite, which are 

considered to be chiefly of the same age as the Woodf ord chert in the 

Arbuckle Mountains and the Chattanooga shale, were thus formed. 

Some of the mud laid down at this time was red, as shown by the red 

color of the shale that it formed. This points to local conditions 

similar to those under which the mud during the Missouri Mountain 

epoch was deposited that is, a near-by, long-exposed, and deeply 

weathered land surface, upon which there was a revival of erosion.
132 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Sedimentation during the Arkansas novaculite epoch was not continuous ; after Middle Devonian time it was interrupted by emergence 

and erosion, as shown by the presence and character of a conglomerate 

at the base of the middle division of the formation in the northern 

part of the Hot Springs district. The absence of this conglomerate 

in much of the De Queen and Caddo Gap quadrangles and in the 

Trap Mountains in the Hot Springs district suggests that the land 

area over which this part of the formation suffered erosion at this 

time may not have been of wide extent, but a conglomerate at this 

horizon was observed in the Potato Hills, near Talihina, Okla. 

Other conglomerates higher in the formation and similarly confined to 

the northern part of the Hot Springs district likewise indicate that 

land at different times was near by.

Life was meager during the Arkansas novaculite epoch. The only 

remains found thus far in Arkansas are a single collection of conodonts from a minutely pebbled conglomerate and conodonts, small 

linguloids, and sporangites from associated shale. This collection 

was made from the middle division of the formation at Caddo Gap. 

Pieces of silicified wood found in a conglomerate in this part of the 

formation near Glenwood, Pike County, Ark., and a piece of silicified 

tree trunk at least 2 feet in diameter, found at the top of the formation near Eosboro, Pike County, indicate the existence of trees of fair 

size on the land. Similar fossil wood occurs in the Woodford chert 

of Oklahoma.

This epoch was ended by an emergence from the sea over much of 

the Ouachita Mountain region. While this area was land much 

erosion took place on it and planed off the novaculite strata north 

of the quadrangles under discussion and in the northern part of the 

Hot Springs district. Many of the rounded novaculite pebbles from 

the eroded strata are found in the overlying conglomerate at the base 

of the Carboniferous rocks. But in the Caddo Gap and De Queen 

quadrangles, as in many other parts of the Ouachita region, so uniform is the character of the beds at the top of the Arkansas novaculite 

that, with the exception of thin, locally distributed conglomerates, 

there is no apparent evidence of an unconformity at this horizon.

CARBONIFEROUS PERIOD

After the period! of erosion at the end of Arkansas novaculite 

time a bed of pebbles was laid down here and there in the Caddo 

Gap and De Queen quadrangles and now constitutes the only 

visible evidence in the quadrangles for a stratigraphic break at the 

base of the Carboniferous. In the northern part of the Hot Springs 

District the pebbles were spread out in a continuous bed and were 

followed by a bed of gray sand, later to form the Hot Springs sand-
GEOLOGIC HISTORY 133

stone; but this sandstone does not extend into the southern part of 

that district, nor jnto the Caddo Gap, De Queen, Mount Ida, and 

Lukfata quadrangles and other areas on the west. The distribution, 

character, and stratigraphic relations of this sandstone and its basal 

conglomerate suggest that the materials composing them came from 

a near-by northern source.

The deposition of the Hot Springs sand was followed throughout 

the Ouachita region by the Stanley epoch, during which mud and 

sand were alternately deposited to a depth of 6,000 feet.

Stanley deposition was in turn followed by Jackfork time, during which fully 6,000 feet of sand accumulated over much if not most 

of the Ouachita area.

The Stanley shale and Jackfork sandstone are exposed through 

the entire length of the Ouachita region, and the Jackfork sandstone is exposed at places in the Arkansas Valley in Arkansas, but 

both formations thin out to the north and west. They are absent 

in the Arbuckle Mountains and at a locality on the north border 

of the Ouachita region near McAlester, Okla., and also in the Ozark 

region. Not only do the formations themselves become thinner 

toward the north, but sandstone beds that form about one-fourth of 

the Stanley shale along the southern border of the Ouachita region 

become thinner or thin out completely before they reach the no^th side 

of the region, and the Jackfork sandstone changes toward the north 

from a formation composed almost entirely of sandstone with very 

little shale to a formation composed largely of shale. This northward thinning of the sandstone beds of the Stanley shale and the dovetailing of thick beds of shale in the Jackfork sandstone to the north 

imply a southern source for the sand and mud that later made up these 

formations. Many small quartz pebbles, one-fourth of an inch or 

less in diameter, occur in the Jackfork sandstone, particularly in 

its lower part, on the southern border of the Ouachita Mountains. 

They become less abundant toward the north. The enormous thickness and comparatively large areal extent of the Stanley and Jackfork indicate that the land mass to the south suffered great erosion.

The black color of the shale in the Stanley and the presence in it 

of many plant fragments, which are usually indeterminable, indicate 

the existence of plant life on the land. Marine fossils have not 

been found in the Stanley except at a few localities in McCurtain 

County, Okla.,85 and none have been found in the Jackfork sandstone except at one locality in the De Queen quadrangle. The practical absence of marine fossils in these formations, combined with

88 Honess, C. W., Geology of the Southern Ouachita Mountains. Okla.: Oklahoma Geol. 

Surrey Bull. 32, pp. 177-178, 1923. 

6242 29 10
134 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

the wide distribution and shallow-water character of the deposits, 

suggests that the formations are for the most part of fresh-water 

origin and that the materials composing them were deposited in a 

great delta formed at the mouths of rivers running north and draining the land area on the south. Any land area that could have supplied so much sediment in so short a time must have been extensive 

and must have been rapidly eroded, and it therefore probably 

included mountains.

Volcanic material that later formed tuff was deposited in the 

southern part of the Ouachita Mountain region early in Stanley time. 

The absence of bedding and of sorting of the rock and mineral fragments forming the tuff suggest that they were laid down on land, 

but the roundness of some of these fragments at some places shows 

that in those places they were deposited in water. As the tuff 

occurs only on the south side of the Ouachita region and thins out 

toward the north and as the size of the fragments of its component 

materials apparently decreases toward the north, it would seem that 

the volcanic materials which it contains were ejected from some vent 

or vents on or near the old land area at the south. The southern 

land area was low and was eroded very little during Devonian and 

possibly during early Mississippian time, but diastrophic movements 

produced mountains on the land during the Stanley and Jackfork 

epochs. The occurrence of the tuff near the base of the Stanley shale 

and the probability that the fragmental materials composing the tuff 

had a southern source strongly suggest that the mountain-making 

movements were accompanied by volcanic activity during which the 

materials for the tuff were ejected.

In parts of Oklahoma the Caney shale, containing in its lower part

an upper Mississippian marine invertebrate fauna and in its upper 

part a fauna and flora of Pottsville (early Pennsylvanian) age, overlies the Jackfork standstone, and in places the Caney is succeeded 

by the Wapanucka limestone, of Pottsville age. The next formation 

in order in that State is the Atoka, also of Pottsville age, but in Arkansas and parts of Oklahoma the Atoka rests upon the Jackfork. 

Although the Caney and the Wapanucka have not been recognized 

in Arkansas, no unconformity has been detected in this State between the Jackfork and the Atoka. Whether an unconformity exists 

or whether the Caney and the Wapanucka are only apparently absent 

and are represented in the upper part of the Jackfork or lower part 

of the Atoka or both is not known, but the lithologic character of 

the Jackfork indicates that it does not represent either of the formations named. The lower part of the Atoka may possibly represent 

one or both of them with such a difference in lithologic character as 

might come about in widely separated parts of the same formation.
GEOLOGIC HISTORY 135

At least 6,000 feet of interbedded sand and mud containing some 

plant remains were laid down during Atoka time in the Caddo Gap 

quadrangle, and there was probably more, because the Atoka, being 

the youngest Paleozoic formation, has doubtless suffered some erosion. Great thicknesses of shale 'and sandstone younger than the 

Atoka are widely exposed in the Arkansas Valley, and the youngest 

of these rocks are of the same age as the Allegheny formation in the 

Appalachian region, which forms a part of the Pennsylvanian series. 

The sediments for the Atoka formation and the younger shale and 

sandstone apparently came from the south, like the sediments for 

most of the older rocks in the Ouachita Mountain region. Geologists 

believe that the clastic materials for the lower Pennsylvanian rocks 

of northern Texas were derived largely from an extensive old land

area on the east and northeast, now covered by later formations. It

appears fairly certain, therefore, that at least a part of the land area 

which supplied most of the material for the enormous thicknesses of 

Carboniferous rocks exposed in the Ouachita Mountains and Arkansas Valley was situated in Louisiana and eastern Texas. The 

location of this old land area may have roughly coincided with that 

of the Sabine uplift.

FOLDING AND TTPLIFT

The area occupied by the Ouachita Mountain region and the 

Arkansas Valley was, taken as a whole, a geosyncline or subsiding 

synclinal trough, not only in Carboniferous time but throughout 

most of the Paleozoic era. Its subsidence began with or before the 

deposition of the mud that formed the Collier shale, of Cambrian age, 

and continued at least through the Allegheny epoch of Pennsylvanian 

time. During this long period there accumulated in this trough an 

enormous amount of sediment, which produced rocks whose exposed 

thickness aggregates a maximum of 41,000 feet and a minimum of 

23,000 feet. At times, however, oscillations in the outer part of the 

earth produced low land areas of greater or less extent, and these 

caused irregularities in the deposition of different beds or formations 

that amounted in some places to their extreme thinning or absence. 

Near the end of the Paleozoic era this subsiding trough was converted into land, and its rocks were folded and faulted. The uplift, 

folding, and faulting in the Ouachita Mountain and Arkansas Valley 

regions were probably contemporaneous at least in part with extensive movements of a like nature in the Arbuckle Mountains, in southern Oklahoma, which, according to Morgan,88 took place at four

88 Morgan, G. D., Geology of the Stonewall Quadrangle, Okla.: Bur. Geology Bull. 2, 

pp. 19-21, Norman, Okla., 1924.
136 SB QUEEN AND CADDO GAP QUADRANGLES, ABKANSAS

different times during the Pennsylvanian epoch namely, near the 

end of Atoka deposition and thus near the end of the Pottsville time; 

near the end of the deposition of the sediments of the Savanna sandstone of Allegheny age; a little before the end of the deposition of 

the sediments of the Wewoka formation of middle Pennsylvanian 

age; near the end of the ideposition of the sediments of the Vamoosa 

formation of late Pennsylvanian age.

The writers are inclined to agree with Morgan 86 and Honess 87 

that the close folding and extensive faulting of the rocks of the 

Ouachita Mountains took place near the middle of the Penns}dvanian.

The folding and faulting were produced by horizontal compression 

movements acting in a nearly north-south direction. That the active 

force affecting the region came from the south is shown by the flattening of the folds northward from the axis of the Ouachita anticline toward Arkansas River and by their final dying out in the 

Ozark region. This force from the south corresponds with the northwestward movement that produced the Appalachian folds, to which 

the folds of the Ouachita region are similar. Many of the folds are 

overturned, some from the south that is, in the same direction as 

that of the active force affecting the region and others from the 

north, in an opposite direction to that of the active force. The 

amount of horizontal compression of the strata in the quadrangles 

has been about half their original extent. The mud, sand, and other 

materials had become indurated probably to a large extent by their 

own weight, but the force that effected the folding further consolidated them into firm rocks, and the permeating waters in places produced new minerals and cemented the particles firmly together. The

shearing force and pressure further modified the deposits by the

formation of cleavage and joint planes.

LATE PENNSYLVANIAN, PERMIAN, AND MESOZOIC TIME 

OUACHITA PENEPLAIN

The De Queen and Caddo Gap quadrangles, as well as the rest of 

the Ouachita Mountain region, have, so far as known, been only 

partly submerged since their emergence near the middle of the 

Pennsylvanian epoch. Much of the area has remained land and has 

consequently undergone erosion from this emergence until now. The 

highest ridges in the Ouachita Mountains stand more than 2,000 feet 

above sea level, but the rocks composing some of the ridges have had 

at least 18,000 feet of strata removed from above them. Had this 

material not been removed a few of these mountains would now have

88 Morgan, G. D., op. cit, pp. 19-21.

87 Honess, C. W., Geology of the Southern Ouachita Mountains of Oklahoma : Oklahoma 

Geol. Survey Bull. 32, p. 259, 1923.
GEOLOGIC HISTORY 137

.altitudes of more than 20,000 feet above sea level. They never attained such altitudes, however, because erosion progressed with

 elevation and may have worn away the rocks nearly as fast as the 

region was raised.

Erosion has not continued at a uniform rate up to the present time; 

there have been intervals when the region was reduced to a low-lying 

one of low or moderate relief, on which eros.ion was at a minimum.

 Such a low-lying area that has a nearly level surface is known as a 

peneplain. The evidence available indicates the successive formation of two peneplains the Ouachita and the Hot Springs. The 

Hot Springs peneplain is described in the account of the Cenozoic

 era. Both peneplains have been largely destroyed by subsequent

 erosion, the Ouachita being now marked merely by the sharp, even

 crests of the Ouachita Mountains and the Hot Springs by low, greatly

 eroded upland surfaces on which there are only smalj tracts of level

 country.

The Ouachita peneplain was produced by a long period of erosion, 

which began near the middle of the Pennsylvanian epoch and con-

 tinued through the Permian epoch and Triassic and Jurassic periods 

to the Lower Cretaceous epoch. If any part or parts of the present 

Ouachita Mountain region and Gulf Coastal Plain were submerged

 during Permian, Triassic, and Jurassic time, evidence of such submergence has not thus far been discovered. The Ouachita peneplain 

has undergone uplifts and tilting probably three or more times. At 

the beginning of the Cretaceous period this peneplain and a large 

area on the south, .including the old land mass in Louisiana and 

mortheastern Texas, were depressed and permitted the Gulf waters 

to extend northward until the shore line passed eastward several 

miles at least north of the south line of the De Queen and Caddo Gap

 quadrangles. How much farther the sea extended is not known, but 

it probably did not completely coyer the quadrangles. During the 

northward advance of the sea the peneplain was doubtless slightly 

lowered by wave erosion. 

The Ouachita peneplain forms the floor upon which the sediments

 of Lower Cretaceous age were deposited ,in the southern parts of the 

quadrangles and farther south, east, and west. The floor is smooth

 except for minor irregularities and south of the Ouachita region 

has a low dip (about 80 feet to more than 100 feet to the mile) to the 

.south. (See fig. 7.)

If this plain were projected northward with a slope of 80 feet to 

the mile its altitude would be found to coincide or nearly coincide 

with that of many of the higher ridges in the northeastern part of 

the De Queen quadrangle and the northern part of the Caddo Gap 

quadrangle. (See fig. 7.) The altitude would be about 2,000 feet
138 QUEEN AND CADDO GAP QUADKANGLES, ARKANSAS

mnossiw

NIV1NHO1AI

a g

-

above sea level in the vicinity 

of Porter Mountain, Tall Peak, 

and Raspberry Peak, in the De 

Queen quadrangle, and about 

1,900 feet at Blaylock Mountain and 1,650 feet at Redland 

Mountain, in the Caddo Gap 

quadrangle. The altitudes'just 

given accord fairly well with 

those of the crests of these and 

near-by mountains and the 

crests of the high ridges above 

which Tall and Raspberry 

Peaks rise, but the projected 

plain would be higher than 

most of the mountains farther 

north and east in the quadrangles and higher than all 

the crests north of the quadrangles. The level attained by 

the crests north of the quadrangles, therefore, has a lower 

dip toward the south than 80 

feet to the mile. The projected 

level would also be higher than 

the Cross Mountains, in the De 

Queen quadrangle. 

In Arkansas the high ridges

of the Ouachita Mountains

are separated from the Gulf 

Coastal Plain by the Athens 

Plateau, but in McCurtain 

County, Okla., a short distance 

west of the De Queen quadrangle, they extend southward 

clear to the Coastal Plain. In 

that county they gradually increase in elevation northward 

from the north edge of the 

Coastal Plain, where the steeply 

dipping hard rocks that produce the ridges farther north 

have at most places been eroded 

down level with the softer rocks. 

The foregoing data show that 

the southward dip of the Oua-
GEOLOGIC HISTORY 139

chita peneplain increases to the south not only in the southern part of 

the Ouachita region but also along the northern edge of the Coastal 

Plain, where it forms the floor for the rocks of Lower Cretaceous age.

The peneplain in Arkansas has also a very low dip toward the 

east. It is about 2,000 feet above sea level in the northeast corner 

of the De Queen quadrangle and the northwest corner of the Caddo 

Gap quadrangle, 1,100 to 1,300 feet above sea level at and near Hot 

Springs, and 500 to 600 feet above sea level at and near Butterfield, 

Hot Spring County, at the east end of the Ouachita Mountains. 

This eastward dip is apparently due to an eastward tilting of the 

part of the Ouachita Mountain region in Arkansas during the down 

warpings of the Mississippi embayment in Upper Cretaceous and 

Tertiary time.

In the De Queen and Caddo Gap quadrangles, as in other parts of 

the Ouachita Mountains, the only remnants of the Ouachita peneplain are the even-crested higher ridges, composed of the hardest 

rocks, the intervening softer portions of its surface having been 

entirely removed and some of the hardest parts having been reduced below the level attained by the higher ridges. The ridges 

have sharp crests, and no level tracts are preserved on them. Many 

or all of the crests may, in fact, have been slightly reduced below 

the level of the original peneplain, and some of the low peaks on the 

ridges, such as Tall and Easpberry Peaks, may have stood above 

the level of the peneplain.

DEPOSITION IK LOWER CRETACEOUS TIME

During the northward advance of the Lower Cretaceous sea across 

the Ouachita peneplain into the De Queen and Caddo Gap quadrangles pebbles of sandstone and novaculite were deposited on the 

beach, upon the beveled edges of the steeply dipping beds of sandstone and shale of Carboniferous age. The gravel bed thus formed 

is the lowest bed of the Trinity formation and to it the name Pike 

gravel member has been applied. Later in Trinity time there was 

an alternation of conditions that brought about the deposition of 

sand, clay, calcareous material, and gravel to a depth of 600 feet or 

more. The gravel was probably laid down on beaches, and the sand 

and clay were deposited on beaches and in deltas at the mouths of 

streams that flowed from the north. The only fossils in these 

deposits are fragments of wood and the bones of vertebrate animals. 

But the calcareous material, most of which was' deposited at two 

times, forming the Dierks and De Queen limestones, was laid down 

in brackish water, as is shown by the molluscan faunas of the limestones. The faunas consist chiefly of fossil oysters. During the deposition of the beds of the De Queen limestone strontium sulphate
140 DE QUEEN AND OADDO GAP QUADRANGLES, ARKANSAS

and calcium sulphate were precipitated from the sea water and 

formed celestite and gypsum, respectively. The comparatively clear 

water in which the oysters and other marine forms lived and contributed their remains for the Dierks limestone gave way toward 

the west, in the De Queen quadrangle, to muddy water in which 

very little or no limestone was formed. In consequence of this the 

limestone merges into clay toward the west. The hard sanoistone of 

Carboniferous age formed rocky headlands and islands at some 

places, as northwest of Murfreesboro, but many or all of these were 

later buried by sediments as the sea gradually encroached toward the 

north upon the land.

No Lower Cretaceous rocks younger than the Trinity crop out in 

the quadrangles herein described, but there are exposures of them 

near Cerrogordo, Ark., only a few miles south of the southwest 

corner of the De Queen quadrangle. These rocks there consist of 

the Goodland limestone and overlying beds of marl and limestone, 

all of which represent the Fredericksburg and Washita groups of the 

Lower Cretaceous series. Whether a part or all of the sediments 

of these two groups were laid down anywhere in the De Queen and 

Caddo Gap quadrangles and later removed through erosion is not 

known.

Deposition during Lower Cretaceous time was ended, in these 

quadrangles, by an uplift that brought the submerged parts of the 

quadrangles above water. After this uplift much of the Trinity 

was eroded from the quadrangles. The erosion was least on the west 

and greatest on the east, where, as near Delight, it removed all the 

higher beds of the formation down to and including the Dierks 

limestone lentil. The amount of erosion at this time in the Ouachita

Mountains is not known, but the Ouachita peneplain was probably 

not reduced to any great extent.

INTRUSION OF IGNEOUS BOOKS

The peridotite that occurs near Murfreesboro, in the Caddo Gap 

quadrangle, appears to be the result of three distinct but closely 

related outbursts of igneous activity.

First, a magma was intruded upward into the Carboniferous and 

Lower Cretaceous rocks, and on cooling and solidifying it became 

a hard rock that is now called intrusive peridotite.

This was followed by exceedingly violent volcanic explosions, 

which blasted a conduit through the older rocks and shattered into 

fragments some of the intrusive peridotite, also some of the Carboniferous shale and sandstone, and other sedimentary rocks that 

formed the walls of the vents. Explosive craters were no doubt 

formed at the surface outlet of these volcanic vents. At the Prairie
GEOLOGIC HISTORY 141

Creek peridotite locality and possibly elsewhere large quantities of 

fragments were ejected into the air and on falling back accumulated 

within the crater in layers dipping toward its center. The fragmental material thus accumulated and some that probably did not 

reach the surface was consolidated to the hard rock now called 

Tolcanic breccia.

The peridotite fragments and altered olivine grains in the lower 

part of the Tokio formation (Upper Cretaceous) on the Kiley place, 

near Murfreesboro, and the altered serpentine grains in the lower 

part of the Tokio formation on the Twin Knobs, also near Murfreesboro, were apparently water-laid like the associated sand, 

gravel, and clay. They may have been derived from outcrops of 

peridotite, but they were probably fragmental material that was 

ejected during volcanic eruptions.

Slightly later occurred another time of explosive volcanic activity, 

during which fragmental volcanic material very similar to that of 

the previous eruption accumulated and subsequently consolidated 

into the hard rocks that are now called tuff and fine-grained breccia. 

These rocks are, so far as known, present only in the Prairie Creek 

peridotite area.

That the several phases of volcanic activity took place after 

Trinity (Lower Cretaceous) time and during or before Tokio (Upper 

Cretaceous) time is shown by the facts (1) that the peridotite has 

penetrated and cut across the nearly flat-lying beds of the Trinity 

formation (figs. 4 and 5), (2) that it is overlain at places by the Tokio 

formation (fig. 5), and (3) that pebbles of it occur in the lower part 

of the Tokio. The pebbles of the peridotite in the Tokio were probably ejected as fragmental material during the volcanic eruptions, and 

if so the eruptions took place during the time when the Tokio was 

being deposited. The several phases of volcanic activity probably 

accompanied the diastrophic movements that produced the downwarping of the Mississippi embayment early in Upper Cretaceous 

time.

DEPOSITION IN UPPER CEETACEOUS TIME

The beginning of Woodbine time in the Upper Cretaceous epoch 

was marked by a northward advance of the Gulf waters into the 

southern parts of the De Queen and Caddo Gap quadrangles. During 

and after this advance thick beds of gravel, sand, and clay were 

laid down in shallow waters, probably on deltas, along beaches, and 

in stream channels. The only fossils that have been found in the 

beds thus laid down are those of land plants. Most of the pebbles 

in the gravel beds are novaculite and were derived by erosion from 

the gravel beds in the Trinity and from the outcrops of the novaculite 

on the north.
142 DE QUEEN AND CADDO GAP QUADRANGLES, AEKANSAS

A thick bed of water-laid volcanic tuff in the Woodbine indicates 

extensive volcanic activity during Woodbine time. This activity 

doubtless took place at or near the same time as that in the areas 

of the peridotite near Murf reesboro. The source of the bulk of the 

volcanic material is, however, not known, though a minor part was 

doubtless contributed by the volcanic explosions near Murfreesboro 

which brought the peridotite to the earth's surface. Most of the 

materials in the tuff and ash are, as shown by previous discussion, 

not related to peridotite. Instead they are similar to but not identical with the syenites and related types of igneous rocks near central 

Arkansas.

The thickest known deposits of tuff in Arkansas and Oklahoma 

lie in Pike County, Ark., and the adjoining counties of Howard and 

Sevie^r in that State. This, combined with the known occurrence of 

volcanic activity at Murfreesboro, Pike County, suggests that the 

vent or vents, through which the enormous quantity of tuff and ash 

in southwestern Arkansas and southeastern Oklahoma were ejected, 

were located in these three counties. The areas of Lower Cretaceous 

and older rocks in these and adjoining areas have been carefully 

studied by numerous geologists, but thus far no evidence of volcanic 

vents except the peridotite vents near Murfreesboro has been discovered. The inference follows that the vents supplying the other 

kinds of volcanic material were perhaps in the southern parts of 

Pike, Howard, and Sevier Counties, south of the De Queen and 

Caddo Gap quadrangles, where they are concealed by beds of Upper 

Cretaceous and Quaternary age.

Woodbine time was ended by uplift and a consequent period of 

erosion. Tokio deposition then fallowed and was apparently accompanied by volcanic activity at the areas of peridotite near Murfreesboro. A bed of water-laid material, possibly peridotite tuff, 

is found at the base of the formation near that place. Also the 

kaolin deposits of the Tokio are of such a character as to indicate 

volcanic activity that resulted in the ejection of fine dust, which 

was deposited in thin beds in the Caddo Gap quadrangle. The 

kaolin of the Tokio formation has been derived by alteration from 

the beds of volcanic dust. Marine fossils have not been found in the 

Tokio formation in the Caddo Gap quadrangle, but they have been 

obtained at localities only a few miles south of the quadrangle.

Deeper water deposits succeeded the near-shore deposits of the 

Tokio formation. Those in the southeast corner of the Caddo Gap 

quadrangle consisted of marl filled with marine shells, to which the 

name Brownstown marl is applied, but still younger beds of sand, 

clay, and chalk of Upper Cretaceous age were laid down south and 

southeast of the De Queen and Caddo Gap quadrangles. The
GEOLOGIC HISTORY 143

Ouachita region and the near-by portion of the Gulf Coastal Plain 

were uplifted at the end of the Upper Cretaceous epoch, and there 

was a consequent withdrawal of the Gulf waters toward the south. 

The De Queen and Caddo Gap quadrangles have so far as known 

remained dry land since then.

The several oscillations of Upper Cretaceous time are briefly discussed as follows by Veatch: 88

As a result of this submergence [Upper Cretaceous] the low-lying area in 

western North America became a great mediterranean sea, which connected 

the Gulf of Mexico and the Arctic Ocean. In the Texas-Arkansas area the

 depression was at first greatest to the southwest, but during the latter part 

of the Cretaceous the movement was reversed and the western region was 

gradually elevated as the area near the Mississippi was depressed. This resulted finally in the development of the Mississippi embayment and in the 

severing of the connection between the Gulf and the interior sea, which was 

thus converted into a series of great inland lakes which persisted through 

much of the Tertiary. Because of this east-west and then west-east tilting 

the lower portion of the Upper Cretaceous, which in central Texas is characterized by thick limestone and light-colored marl beds, is in Arkansas and 

Indian Territory composed entirely of near-shore sands with no marine fossils; 

"while the upper portions, which in Texas are dark-colored calcareous clays, 

contain in Arkansas, Mississippi, and Alabama a large percentage of chalk 

and chalk marls.

DRAINAGE DURING OEETAOEOUS TIME

The drainage of the present Ouachita Mountain region during 

Lower Cretaceous time, when the region was presumably a low 

southward-sloping peneplain (the Ouachita peneplain), must have 

been toward the south into the sea. The present Ouachita Mountain 

region was in fact probably reduced so nearly to a plain that the 

courses of the streams were largely independent of the structure of 

the rocks. After the region was elevated at the end of Lower Cretaceous time the streams continued to flow southward but across 

the area of newly formed unconsolidated sediments. These sediments

 doubtless overlapped the Ouachita region for some distance beyond 

their present margin, and upon them the southward-flowing streams 

along the south side of the region were superimposed. When their 

channels were later cut down to the beveled upturned edges of the 

hard Paleozoic rocks below, they were incised therein regardless of 

the structure of the rocks.

But the southward-flowing streams in most of the Ouachita Mountain region have apparently had a different history, for there is 

little or no evidence that Cretaceous or later deposits ever covered 

more than a small part of the region. Their history is complicated,

88 Veatch, A. C., Geology and Underground Water Resources of Northern Louisiana and 

Southern Arkansas: U. S. Geol. Survey Prof. Paper 46, p. 22, 1906.
J44 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

and probably no single explanation can account for their courses 

across the edges1 of the rocks and through the ridges. An explanation here offered is that the streams may have flowed toward the 

south, away from the axis of the Ouachita anticline, during the 

gradual emergence of the Ouachita Mountain region from the sea. 

This emergence was so slow and much of the 18,000 feet of Carboniferous rocks removed by erosion was so soft at that time that the 

most vigorous streams easily kept their courses across the folds asthe folds increased in height or as the streams worked down to them,, 

so that, when the edges of the Arkansas novaculite and other hard 

strata were reached, the courses had become so well established that 

they were maintained across these strata.

The downwarping of the Mississippi embayment during Upper 

Cretaceous and Tertiary time was accompanied by an eastward 

tilting of much of the southward-sloping Ouachita region, so that 

the region now slopes to the southeast. Much of the southward 

drainage was therefore diverted toward the southeast. The southeastward courses of Saline, Ouachita, Caddo, and Little Missouri 

Rivers may thus be explained. The similar course of ArkansasEiver may also be explained in this way, though, as believed by 

Branner,89 the drainage in the Arkansas Valley flowed westward 

during Permian, Triassic, and Jurassic time. If this is true there 

has been a reversal of the Arkansas drainage.

The parts of the courses of the streams that are in the east end! 

of the Ouachita Mountain region may have been superimposed upon 

Upper Cretaceous sediments, though it appears that the east end of 

the region was not covered by sediments of this age.

TERTIARY AND QUATERNARY TIME

Erosion was accelerated by uplift at the end of Upper Cretaceous 

time, and it lowered the surface rapidly along the belts of rock of 

least resistance, leaving the edges of some of the more resistant 

rocks standing up as mountain ridges. In this way the Hot Springs 

peneplain was produced in parts of the Ouachita Mountain region,, 

including the De Queen and Caddo Gap quadrangles. In these 

quadrangles the peneplain stood at the same level as the present 

dissected plateau surfaces of the Mazarn and Cove basins and much, 

of the Athens Plateau. During the lowering of the region by 

erosion which produced the peneplain the edges of the steeply dipping Arkansas novaculite withstood erosion and persisted as ridges.. 

The edges of the Jackfork sandstone in the Athens Plateau in the 

Caddo Gap quadrangle also produced low ridges upon the peneplain.

88 Branner, J. C., The Former Extension of the Appalachians across Mississippi, Louisiana, and Texas: Am. Jour. Sd, 4th ser., vol. 4, pp. 358--360, 1897.
GEOLOGIC HISTOEY 145

Owing to the various hardnesses of the rocks, the part of the Caddo 

Basin in the Caddo Gap quadrangle was apparently not reduced 

to a peneplain at this time.

The part of the peneplain in the Ouachita region in Arkansas has 

a general southward and southeastward dip toward the Gulf Coastal 

Plain. Its gradient is much less than that of the Ouachita peneplain, 

which shows that the post-Ouachita uplift that resulted in the tilting 

of the surface toward the south and east was greater in the interior 

than near the coast. The highest part of the Hot Springs peneplain 

is in and north of the northwest corner of the De Queen quadrangle, 

where it attains an altitude of about 1,250 feet above sea level, and 

the lowest part is along the eastern edge of the Ouachita region, 

where its altitude is about 400 feet. (See fig. 7.) The peneplain 

along its southern border in the quadrangles under discussion stands

750 feet above sea level. The relation of the peneplain to the Tertiary 

deposits in Arkansas has not been fully worked out, but at the few 

places where the authors have studied it, along the eastern margin 

of the Ouachita Mountain region, it appears to pass beneath the 

Eocene (early Tertiary) strata of the Coastal Plain. If this is its 

position, the peneplain is of early Tertiary age.

The streams on the Hot Springs peneplain were graded and built 

up wide flood plains, over which they meandered regardless of the 

structure of the rock strata, though the outcropping edges of the 

Arkansas novaculite and those of the Jackfork sandstone in many 

places were not reduced to the level of the peneplain. The edges of 

these formations produced ridges which still persist. Some of the 

streams were able to maintain their courses across the edges of these 

hard strata while the region was being reduced to form the peneplain. 

In this way water gaps were cut in the ridges.

Beginning with the Eocene epoch of the Tertiary period, the Mississippi embayment was again submerged by a northward extension 

of the Gulf of Mexico. The sea did not reach the quadrangles under 

discussion, and the thin deposits of water-worn gravel found here 

and there on the Athens Plateau near Athens, in the Caddo Gap quadrangle, and similar deposits over the higher parts of the east end of 

the Athens Plateau east of this quadrangle, were probably laid down 

by streams as flood-plain deposits during the Tertiary period.

Later a succession of uplifts halted by periods of stability and 

depression elevated the region about 500 feet to its present altitude 

and forced the Gulf waters back to their present position. This elevation rejuvenated the streams and enabled them to carry away in a 

short time most of their former flood-plain deposits and to dissect the 

Hot Springs peneplain so completely that little comparatively level 

upland is left on the present plateau surface. The larger streams, 

such as Little Missouri, Cossatot, and Saline Rivers and Rolling
146 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

Fork, have gradually incised their channels to a depth of as much 

as 350 feet in the hard Paleozoic rocks. These streams probably 

inherited their crooked courses from their predecessors, which ran 

in similar courses across the Hot Springs peneplain. Many of 

the smaller streams have partly or wholly eroded their valleys in the 

soft shale between the nearly east-west ridges of hard sandstone. 

Such streams flow toward the west or toward the east, whereas the 

larger streams usually have southward courses. A trellised arrangement of the streams has thus been produced in the Athens Plateau 

in these quadrangles. (See pi. 1.)

The cutting of the stream valleys from the Hot Springs peneplain 

down to their present level in the De Queen and Caddo Gap quadrangles has not been continuous. There have been times, as shown by 

terrace deposits, when the streams reached grade. These deposits 

are few, and their areal distribution is small along the streams in the 

Athens Plateau and farther north. This is due to the great hardness 

of the rocks there, which prevented the streams from cutting wide, 

flat-bottomed valleys. These streams have considerable fall, though 

in some stretches their currents are comparatively slow and their 

valleys are widened somewhat. In such places the streams have 

deposited some alluvium.

The larger streams and many of the smaller ones in the Coastal 

Plain in the southern parts of the quadrangles, where the rocks are 

mostly unindurated sand, clay, and gravel, have cut their channels 

down to base level, and the larger ones have cut wide, flat-bottomed 

valleys in which extensive flood-plain deposits have been laid down. 

These deposits occur at various altitudes, the highest being as much 

as 150 feet above the streams.

ECONOMIC GEOLOGY

The principal mineral resources of the Caddo Gap and De Queen 

quadrangles are clay, diamonds, and road material, all of which 

have been mined. Lead, zinc, and antimony minerals, quartz crystals, 

slate, asphalt, building stone, and limestone for lime have been mined 

at times, and deposits of tripoli, pyrite, marcasite, iron ore, manganese ore, and gypsum have been explored.

The soils of the quadrangles are a source of considerable wealth, 

though they are for the most part not naturally so fertile as soils 

that are underlain by rocks of other sorts. The water resources 

are valuable for both water supplies and the development of power. 

Timber is one of the most valuable natural resources and will continue to be one for an indefinite period, if proper care is given to 

the forests.
ECONOMIC GEOLOGY 147

DIAMONDS 

HISTORY AND OCCURRENCE

The first diamonds found near Murfreesboro, which were the first 

found in Arkansas, were picked up on the Pivairie Creek peridotite 

area (pi. 10) on August 1, 1906, by John W. Huddleston. Diamond 

mining has continued intermittently at several mines from the date 

of Huddleston's discovery to the present time.

Nearly all the diamonds have been found within the exposures of 

the peridotite at the Prairie Creek, Kimberlite, and American peridotite areas, though a very few have been found along streams where 

they have been washed from these areas, and the finding of several 

small diamonds has been reported from areas of the Woodbine 

formation, 3 to 4 miles south of Corinth, The mines that have

produced diamonds are the American, Kimberlite, Mauney, Ozark, 

and Arkansas. (See pis. 10 and 14.) The diamonds at these mines 

have been found not only on and near the surface but also at depths 

of 20 feet. How much deeper1 the diamonds extend is not known, 

but they probably occur at a depth much greater than that to Avhich 

mining can be carried.

The yield of diamonds in carats per load of diamond-bearing ma 

terial differs from place to place in the mines and with depth. This 

yield as it has been determined from the great amount of work at 

one mine, is 1 carat for 8 loads (16 cubic feet each) of diamondbearing material.

Most of the diamonds from the Arkansas, Ozark, and Mauney 

mines have been obtained within the area or areas in which the 

volcanic breccia is exposed. The areal distribution of the breccia 

at the surface of these mines is shown on Plate 10.

On the Riley place, half a mile northeast of the Ozark mine, the 

Tokio formation contains pebbles of peridotite and grains of altered 

serpentine. The material is possibly peridotite tuff. The Ozark Diamond Mines Corporation washed 1,000 loads (16 cubic feet each) of 

material from the Tokio at that locality but found no diamonds.

PRODUCTION AND CHARACTER

The number of diamonds that have been found near Murfreesboro, Ark., since their discovery in 1906 is only partly known, for 

the mining companies have withheld from publication the complete figures of production. The production so far as known to the 

authors includes at least 10,000 diamonds up to the end of 1923.

The bulk of the diamonds from the mines have been held by the 

mining companies, though some uncut stones have been given away 

or sold, and some cut stones have been sold. Cut stones were first
148 I>E QUEEN AND CADDO GAP QUADBAFGLES, ARKANSAS

offered to the public in 1921 by Tiffany & Co., of New York, and by 

the Charles S. Stifft Co., of Little Kock, Ark.

The diamonds that have been found range in weight from a very 

small fraction of a carat to many carats. Some are so small that 

250 diamonds would be required to weigh 1 carat. The largest 

diamond, which was found in the Arkansas mine, weighed 40.23 

carats; another from the same mine found in September, 1921, 

weighed 20.25 carats; and a third stone weighing 17.86 carats was 

found in the Arkansas mine in May, 1917. Pictures of the lastmentioned diamond and nine others from the Arkansas mine are 

shown in Plate 17, A. The average weight of the 3,000 diamonds produced from the Arkansas mine to the end of 1920 was 

about 0.4 carat,90 but the average weight of the entire production of 

all the mines is probably between 0.3 and 0.4 carat.

Most of the diamonds are white, brown, or yellow. There is, 

according to Kunz and Washington,91 a large proportion of white 

stones, most of them of high grade in color, brilliancy, and freedom 

from flaws. They also say that many stones are as fine as any that 

have ever been found and that some of the yellow ones are of exceptional quality and color. Kunz92 also makes the following statement in describing several yellow, brown, and white stones from the 

Arkansas mine: "These are absolutely perfect and are equal to 

the finest stones found at the Jagersfontein mine, or that were ever 

found in India."

The following statement regarding the diamonds from the Mauney 

and Ozark mines was supplied in 1921 by Austin Q. Millar, of the 

Kimberlite Diamond Mining & Washing Co.:

From a careful examination of several thousand diamonds the percentages

of yield of the various grades of the mine run are: White stones, 40; yellow, 

22; brown, 37; true bort, 1. The gem material of the yellow, the deep canary, 

is most magnificent, and the mahogany shade of the brown is equally desirable. 

The white gem material is matchless for purity, and about 10 per cent of the 

stones classed as white are of this grade. * * *

Their crystallographic characteristics are distinct. As the larger proportion 

of the recoveries belong to the more complex forms of the isometric system, 

the trisoctahedron and hexoctahedron predominate more than the octahedron 

or dodecahedron. Rarely are crystals recovered that present sharp angular 

faces, the characteristic rounded (convexed) surfaces greatly predominating. 

The true bort is translucent with a radial structure and occurs in rounded 

forms.

Stones have been found with a blue or pink tinge, and occasionally a 

" frosted " or etched white is noticeable in the recoveries.

80 Kunz, G. P., Eng. and Min. Jour., vol. 103, p. 160, 1921.

a Kunz, G. F., and Washington, H. S., Diamonds in Arkansas: Am. Inst. Min. Eng. 

Trans., vol. 39, pp. 173-174, 1909.

92 Kunz, G. F., Precious Stones: Mineral Industry, vol. 27, pp. 621-622, 1919.
U. S. GEOLOGICAL SURVEY BULLETIN

3 6 10 

A. DIAMONDSIFROM THE ARKANSAS MINE, NEAR MURFREESBORO, ARK.

These diamonds are in the Col. Washington A. Roebling collection in the U. S. National Museum. 

Their weights in carats are as follows: 1, 11.21; 2, 6.83; 3, 3.30; 4, 2.77; 5, 17.86; 6, 4.40; 7, 1.19; 

8, 0.91; 9, 2.50; 10, 1.40. Four-sevenths natural size

l^P^

B. A CLUSTER OF QUARTZ CRYSTALS FROM THE CRYSTAL MOUNTAINS, ARK.

About two-fifths natural size :--
U. S. GEOLOGICAL SURVEY BULLETIN 808 PLATE 18

A. DIAMONDS BEING MINED AT THE ARKANSAS MINE BY MEANS OF A JET 

OF WATER AND THEN CARRIED THROUGH A SLUICE TO THE PLANT

T"

li. DIAMOND PLANT AT THE ARKANSAS MINE

Here the sluiced material is sized and jigged. Then the concentrates, after being placed on 

. smooth sheets of metal, are carefully searched for stones
ECONOMIC GEOLOGY 149

Fragments and fractures were much more noticeable when mining was being 

done in surface material; but at slight depth in the undisturbed volcanic 

ground these features were almost entirely absent.

MINING AND TREATMENT OF DIAMOND-BEARING MATERIAL

Many diamonds, probably several hundred, have been picked up by 

miners from the surface of the peridotite areas, especially the Prairie 

Creek area, but most of the diamonds that have been produced have 

been obtained by washing the diamond-bearing material. Different 

methods of mining and washing have been employed, as required by 

the character of the diamond-bearing material, which varies not only 

from one locality to another but also with depth.

Much of the decomposed peridotite, including the surficial black 

soil called "black ground" and the underlying "blue ground,' :

" yellow ground," and " green ground," is soft enough to be washed 

for the recovery of the diamonds without being first crushed or 

weathered. Most of the " black ground " is very sticky, like gumbo, 

when it is wet, so that it disintegrates with some difficulty in the 

washing plants.

All the mining has been done in shallow open cuts. Hydraulic 

mining has been used to some extent, but most of the work has been 

done by hand and by means of plows and scrapers. Whenever the 

hydraulic method is employed, the water carries the soft weathered 

diamond-bearing material through a sluice trough. The concentrates 

from the sluice trough are then jigged by hand in small sieves or 

run through a small plant equipped with screens and jigs. (See pi. 18.) 

Then the jigged concentrates are placed on smooth sheets of metal 

where they are carefully searched for diamonds.

Much of the material .that has been mined, however, has been 

hauled in tramcars with a capacity of 16 cubic feet each to the washing plants. A log washer was used for a short time in the Ozark 

washing plant, but its use was not a success on account of the sticky 

nature of the " black ground " that was washed in it.

Washing pans of the type common in the South African diamond 

fields have been used successfully. A pan of this type is circular, has 

a flat bottom, and rests in a horizontal position. At its center is a 

vertical revolving shaft to which radiating arms are attached. On 

these arms are metal teeth that revolve and stir the diamond-bearing 

material that is fed into the pan. During this stirring the diamonds 

and associated heavy minerals gradually settle to the bottom of the 

pan, and ,the clay and other light minerals rise to the surface and 

flow out of the pan near its center. The concentrates thus obtained in 

the bottom of the pan are next sized and then jigged. The jigged 

6242 29 11
150 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

concentrates are carefully searched for diamonds on metal-covered 

tables or are washed with water over a greased table. This table is 

covered with a thick coat of grease and is shaken rapidly from side 

to side by an eccentric. When the concentrates are washed across 

the table the grease sticks to and holds the diamonds, whereas it does 

not stick ,to the other minerals, most of which are therefore washed 

off the table. The grease with its included diamonds and other 

minerals is removed from the tables from time to time. The diamonds are then freed from the grease by converting it into soap or 

by putting i,t into boiling water.

CONCENTRATE MINERALS ASSOCIATED WITH THE DIAMONDS

A number of minerals besides diamonds are concentrated during 

the treatment of the diamond-bearing material. They are hematite, 

limonite, barite, colorless quartz, amethyst quartz, magnetite, pyrope, 

almandite, schorlomite (or melanite), chromite, pyrite, diopside, and 

epidote. The quantity of each mineral varies somewhat from place 

to place, but in general the most abundant have been named first 

and the least abundant last. A few specimens of amethyst quartz 

of gem quality have been found, and some of them have been cut for 

use in jewelry. A small number of pebbles of the dense chalcedonic 

varicolored novaculite that are found on the surface at the diamond 

mines have also been cut for this use.

ANTIMONY

The antimony deposits of the De Queen quadrangle have been 

described in a number of reports, the most important of which are 

the following:

Wait, C. B., The antimony deposits of Arkansas: Am. Inst. Min. Eng. Trans., 

vol. 8, pp. 42-52, 1880. *,

Comstock, T. B., A preliminary examination of the geology of western central 

Arkansas: Arkansas Geol. Survey Ann. Kept, for 1888, vol. 1, pp. 136-147, 

1888.

Jenney, W. P., The lead and zinc deposits of the Mississippi Valley: Am. 

Inst. Min. Eng. Trans., vol. 22, pp. 206-208, 1894.

Ashley, G. H., Geology of the Paleozoic area of Arkansas south of the 

novaculite region: Am. Philos. Soc. Proc., vol. 36, No. 155, pp. 217-318, 1897. 

Reprinted in Contributions to Biology from the Hopkins Seaside Laboratory, 

Stanford Univ., No. 12, pp. 306-308, 1897.

Hess, F. L., The Arkansas antimony deposits: U. S. Geol. Survey Bull. 340, 

pp. 241-252, 1908.

Shriver, E. H., Antimony deposits of Arkansas; Min. and Sci. Press, vol. 114, 

No. 26, pp. 920-922, June 30, 1917.

Mitchell, G. J., Antimony in southwestern Arkansas: Eng. and Min. Jour.- 

Press, vol. 114, pp. 455-456, 1922.
ECONOMIC GEOLOGY 151

The deposits were examined by Mr. Miser in July, 1916, when 

practically all the mines were in operation, but the description of 

their general features which is given below is taken in large measure 

from the above-listed reports.

The deposits occupy a narrow belt about 8 miles long lying along 

the northern edge of Sevier County, near Antimony post office and 

the village of Gillham. The location of the mines is shown on 

Plate 3. The exact date otf discovery of the deposits is not positively 

known, but it seems to have been in the winter of 1873-74. Mining 

operations were begun immediately and have been carried on from 

time to time whenever high prices for antimony permitted its economic recovery. The last mining was done in 1917, though no ore 

has been marketed since 1916.

The country rock is the Stanley shale, which has high dips, reaching in places 90°, and a strike of N. 70°-80° E. Owing to the 

absence of distinctive beds the determination of the structure here, 

as in most other places where the Stanley is the surface formation, 

is practically impossible. Although fissure veins of massive and 

comby quartz are common in this and older formations over much 

of the Ouachita area of Arkansas and Oklahoma, it is only in the 

vicinity o»f Gillham and Antimony that they are known to carry 

antimony minerals. An interesting exception is the reported occurrence of crystalline native antimony near Kirby, in the Caddo Gap 

quadrangle. While the authors were in that locality they were shown 

a piece of this mineral weighing a pound or more, but they were 

informed that it was the only piece that had been found. Also a 

second specimen of this native metal that is stated to have been found 

at a locality near Kirby was shown to Mr. Miser by J. N. Garner, of 

Nashville, Ark. The veins that carry the antimony minerals follow 

the bedding planes of the sandstone and shale in which they are 

found, but some small veins and a few larger ones cut across the 

bedding. The principal veins are therefore vertical or nearly so. 

They are slickensided, showing both horizontal and vertical striations, and the black shale on either side has been disturbed somewhat 

by the movements which produced the striations. The thickness 

ranges from a feather edge to 4 feet but is commonly about 1 foot. 

Although quartz constitutes most of the gangue, some angular fragments of shale are included in the vein. The country rock was not 

affected during the introduction of the quartz, and even the included 

fragments remain unaltered. In some places the surface outcrop, is 

marked by protruding ledges of quartz; in others by loose fragments.

The ore bodies occur in lenticular masses ranging in thickness from 

a feather edge to 2^ feet. Besides quartz they contain as original minerals stibnite (Sb,S3 ), jamesonite (2PbS.Sb2 S3 ), zinkenite
152 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

(PbS.Sb2S3 ), galena (PbS), sphalerite (ZnS), pyrite (FeS2 ), chalcopyrite (Cu2S.Fe2S3 ),siderite (FeCO3 ),andcalcite (CaC03 ). Traces 

of arsenic, bismuth, cadmium, cobalt (?), silver, and rarely gold are 

found. Cervantite (Sb2O3 .Sb2O5 ) andbindheimite (PbO.Sb2O5 .H2O) 

occur as oxidation products of stibnite and jamesonite, respectively. 

The commercial ores are antimony oxide and sulphide and lead, minerals, which in places are silver bearing. At depths of 40 to 115 feet 

from the surface these ores contain admixtures of sphalerite and other 

impurities, which have been removed through solution from the upper 

parts of the veins. The following analyses reveal the purity of the 

stibnite, which is the chief ore mineral, and of the cervantite:

Analysis of stitmite from Stewart mine

 Antimony________________________________ 69.87 

Sulphur_________________________________ 27. 91

' Iron___________________________________ .02 

Zinc___________________________________ .01 

Silica________________________________. 2.69 

Silver ________________________________ ' None.

100.50 

Analysis of ore from Antimony Bluff slwft

[C. E. Wait, analyst]

Stibnite_______________________________ 99.711

Chalcopyrite_________________ ___________ . 055

Bismuthinite __________________________ . 005

Gangue ^_ _______________________ . 229

Silver _ _ _____________________ None.

i 100. ooo 

Analysis of cervantite from Antimony Bluff shaft

[C. E. Walt, analyst]

Antimony _ _ ______________ 76. 38

Oxygen _______________________,__ 20. 03

Sulphur_______________________________ . 01 

Oxide of iron_____________________________ . 12

Silica________________________________ 1.19 

Water ________________________________ 2.23 

Silver___ _________________________ None.

99.96

The paragenesis of the vein minerals is not known except that most 

of the quartz preceded the metallic minerals, as shown by their occurrence on the crystal faces of the comby quartz, and that some of the 

quartz was deposited with the metallic minerals. Their origin also 

is not clear. Many of the quartz veins in McCurtain County, Okla., 

contain orthoclase and are regarded by Honess 93 as quartz-orthoclase

98 Honess, C. W., Geology of the Southern Ouachita Mountains of Oklahoma: Oklahoma 

Geol. Survey Bull. 32, pp. 39-40, 48-49, 64-66, 1923.
ECONOMIC GEOLOGY 153

pegmatites. The metallic minerals near Gillham and some or all of 

the quartz associated with them were probably derived from an 

igneous magma. The nature of the minerals, as pointed out by 

F. L. Hess and G. J. Mitchell, suggests this origin.

For an igneous origin it is necessary to assume the existence of concealed masses of intrusive rocks nearer than the peridotite areas at 

Murfreesboro. A dike of ouachitite, as stated on page 100, was found 

recently by Mitchell a few miles east of Gillham. If the origin of 

the veins is related to the intrusive rocks, then, as stated by Hess, 

" their age would be but little less than that of the intrusions " 

early Upper Cretaceous. Hess says:

With such a deep-seated origin it is probable that the lenses of ore will 

alternately make and pinch out to a considerable depth, and in times of high 

prices for ore * * * some of the mines might be worked at,a profit. It 

can not be stated, however, what the vertical extent of any ore shoot may be, 

and below the ground-water level varying amounts of impurities consisting of 

zinc blende, chalcopyrite, and iron pyrite are to be expected.

SLATE 9<

GENERAL FEATURES

In 1902 the Southwestern Slate & Manufacturing Co. was organized to operate in Polk and Montgomery Counties, Ark. Title was 

acquired to large tracts of land, and much money was invested in 

preparations for conducting an extensive slate business when shipping facilities, which were expected soon, could be had. Failure to 

obtain transportation caused the reorganization of the company and 

the change of its name to the Southwestern Slate Co., in 1903. The 

operating plant, which is at Slatington, in the Caddo Gap quadrangle, contains one saw, one planer, and one rubbing board. So 

far as known only milling slate has been produced, a considerable 

amount of this having been put on the market, principally for 

electrical equipment.

The work of these two companies gave an impetus to prospecting 

for slate, and various persons and companies acquired title to slate 

lands in the northeast corner of the De Queen quadrangle and the 

northern part of the Caddo Gap quadrangle. A small production of 

roofing slate has been reported from time to time.

Five formations of the quadrangles contain slate. These are the 

Mazarn, Womble, Polk Creek, and Stanley shales and the Missouri 

Mountain slate. Only the last two of these have been prospected

84 Full descriptions of these deposits may be found in the following reports:

Dale, T. N., and others, Slate Deposits and Slate Industry of the United States: U. S.

Geol. Survey Bull. 275, 1906; Slate in the United States: U. S. Geol. Survey Bull. 586,

1914. 

Purdue, A. H., The Slates of Arkansas, Arkansas Geol., Survey, 1909 ; The Slates of

Arkansas: U. S. Geol. Survey Bull. 430, pp. 317-334, 1910.
154

much, and most of the prospecting and developing has been done in 

the Missouri Mountain slate.

MAZARN AND WOMBLE SHALES

As their names imply, the Mazarn and Womble shales are composed mainly of shale. They generally show no indication.of. slaty 

cleavage, but parts of the Mazarn shale and the base of the Womble 

shale show well-developed slaty cleavage, which is conspicuous in 

the stream beds, by the roadside, and in other places where the shale 

is exposed. The cleavage usually is at a high angle to the bedding, 

and as it appears to be developed best in those-parts.of- the forma,- 

tion where the layers are of different colors, " ribbons" are very 

common on the cleavage surfaces. (See pi. 6, A.) These ribbons consist of alternating green and blue bands from one-fourth of an inch 

to 2 inches thick and are due to original differences in the color of the 

shale from which the slate was formed. In places the slate is sufficiently indurated for temporary roofing, but generally it is too soft 

to withstand the weathering agencies long. It is also, in all places 

where observed, so closely jointed as to prevent the quarrying of 

blocks of commercial size, and its banded or " ribbon" structure 

would render it undesirable for commercial slate, even though it 

possessed all the other requisite qualities.

POLK CREEK SHALE

The Polk Creek shale in most places is only about 100 feet thick, 

and owing to this fact and to the folding in the rocks of the region 

it crops out as narrow belts, most of which run along the bases of 

the mountains. This formation, like the Mazarn and Womble shales, 

is commonly a shale, but locally slaty cleavage is well developed 

in it. In places this slate is banded, but elsewhere it is of a uniform 

black color, is^iard, has a metallic ring, and contains large numbers 

of graptolite fossils. Jointing is very common in both the shale 

and the slate. On account of the comparatively small part of this 

formation in which slaty cleavage is well developed and the abundance of the joints it does not give much promise as a producer of 

commercial slate; there may, however, be places from which such 

slate could be obtained.

MISSOURI MOUNTAIN SLATE

The Missouri Mountain slate is widespread over the quadrangles 

and crops out in many places near the bases of the mountains, 

though it is found also high on some of the slopes, or even in notches
ECONOMIC GEOLOGY 155

on the crests of the ridges. Though it does not enter into the minute 

folding of the region, like the Polk Creek shale, it partakes of the 

principal folding.

This slate has been rather extensively prospected all the way from 

Board Camp Creek, in the De Queen quadrangle, eastward across 

the Caddo Gap quadrangle and to Ouachita River beyond. It has 

been most extensively worked at Slatington, in the Caddo Gap quadrangle, but there are other prospects of considerable magnitude. It 

has been so widely prospected not only on account of its promising 

character as a source of commercial slate but also because of the 

favorable location and nature of its outcrops, most of which are in 

bluffs or well up on the mountain slopes. As the slate is exposed in 

the face of the bluffs, no labor or expense for removing surface material is imposed upon the prospector; and the height of the outcrop

on the slope permits all waste material to be dumped easily. It 

ranges in thickness from about 300 feet to 50 feet or less, the thickest 

portion running along the northern edge of the quadrangles. In 

some of the closely compressed anticlines it is folded over upon itself, 

and its thickness appears to be double the real thickness. There is 

such a fold in the part of Caddo Mountain that is south of Wagner 

Creek, in sec. 15, T. 4 S., R. 26 W., where the slate is exposed for 600 

feet and lies between heavy walls of the Arkansas iiovaculite.

The formation produces buff, red, and green slate. Though all 

these colors may and commonly do occur in the same quarry, the 

red is predominant. It is a clay slate of remarkable homogeneity, 

sandy or other impure layers being absent. In shade it ranges from 

scarlet to dark red, but that of any particular quarry is likely to be 

uniform. On exposed surfaces it presents a rich, pleasing appearance. On account of its homogeneous nature no traces of the original 

bedding are to be seen. This fact, together with its great thickness, 

make it impracticable in most places to determine the direction of 

the cleavage with reference to the bedding planes. In some places 

where it is near the overlying Arkansas novaculite the cleavage is 

plainly parallel with the bedding, but it is probable that the cleavage 

is usually oblique to the bedding.

In; most parts of the formation this slate is intersected by joints 

that run in all directions, but in favorable places these are not so 

numerous as to prevent the quarrying of large blocks. The slate 

cleaves with fairly even surfaces and can readily be split into sheets 

a quarter of an inch thick and less. Some parts have a semimetallic 

ring, but most of it produces a dull sound when struck. In many 

places the intense folding of the region has produced short, wavelike wrinkles in the slate, which quarrymen call " curl" arid which 

are avoided in prospecting. Any quarry that shows a considerable
156 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

amount of " curl" may as well be abandoned. In other parts two 

sets of cleavage planes are locally developed. These may be detected 

by the splitting up of the exposed surfaces into small prisms shaped 

like shoe pegs. Such exposures as this should be avoided by the 

prospector.

Sheets of a considerable size are seldom found on the slopes, and 

hence it appears that this slate weathers readily. If this inference 

is correct, the slate could not be used for roofing. It is hoped, however, that this statement will not prevent anyone from experimenting 

with it by putting it into actual use for roofing, as this alone can 

determine its fitness for this purpose. In the only instance that has 

come to the writer's attention in which shingles of this slate were 

used for roofing, they went to pieces after a few years' service. But 

the result of this one trial should not be taken as final, for slate from 

another quarry might last many years. The best way to-test it is 

for the people of the slate area to use it on small and temporary 

buildings. Such a test should be made of the slate of every quarry 

that will produce shingles, for if any of this slate should be discovered with lasting qualities its beautiful color would at once put 

it in great demand, especially for buildings with gray walls or 

trimmings.

At present slate is in demand for inside fittings, such as laundry 

tubs, wainscoting, lavatories, switchboards, and floor tile. This 

slate is too soft for flooring but is well adapted for all the other 

purposes, especially for switchboards, for which practically all the 

product of the quarries at Slatington has been used. Several samples 

of this slate have been tested for conductivity. The results of the

tests are given in United States Geological Survey Bulletin 430,

pages 329-330, 1910, and " The slates of Arkansas " (Arkansas Geological Survey), pages 59-62,1909.

Because of its softness and homogeneity, this is in all ways a 

desirable slate to work. It splits, saws, and planes easily and soon 

takes a polish on the rubbing bed, but in drying after it has been 

polished, it is liable to check, and the number of pieces thus lost 

greatly reduces the profit of working it. The checking is sometimes at right angles to the cleavage and sometimes parallel with 

it that is to say, the worked pieces may either crack perpendicularly 

to their faces or they may split apart. If some method of working 

can be devised that will avoid this checking, the slate industry of 

Arkansas will become important and profitable.

Red and green varieties of this slate have been quarried half a 

mile south of the village of Caddo Gap, and have been ground for 

use in the manufacture of asphalt roofing.
ECONOMIC GEOLOGY 157 

STANLEY SHALE

Shale at the base of the Stanley has been altered to slate in some 

parts of the closely folded synclines in the mountainous districts in 

the northeast corner of the De Queen quadrangle and the northwest 

corner of the Caddo Gap quadrangle. To much of this slaty phase of 

the Stanley, particularly the basal 150 feet or less, the name " Fork 

Mountain slate " has been applied in the above-mentioned reports. 

This slate lies normally above the Arkansas novaculite, but in many 

places, owing to overturning, it lies beneath that formation on the 

mountain slopes. If on one side of a valley or a ridge it lies above 

the novaculite, on the opposite side it is most likely to lie below the 

novaculite. Where the slate dips into the mountain it can easily be 

detected, for in these places it forms bluffs; but where it dips with 

the mountain slope it may be overlooked.

This is a hard slate, usually gray, but portions are black, and on 

weathered surfaces it is green or chocolate-colored. Thin sandy or 

quartzitic layers are numerous. The cleavage usually is well developed and occurs at all angles to the bedding planes. " Ribbons " 

not uncommonly occur in the gray portion. Some of the slate has 

great strength and toughness and is highly sonorous, but much of 

it is so soft that it does not give much promise of producing commercial slate. In most places jointing is so common as to render 

the slate worthless, but it must not yet be concluded that exploiting 

will find all of it so. Prospectors should not neglect this slate. 

Though it certainly never would do for milling, if found sufficiently 

free from joints and sandy seams it would make shingles of exceptional quality.

ASPHALT DEPOSITS

GENERAL FEATURES

The asphalt impregnates nearly horizontal beds of loose sand in 

the basal part of the Dierks limestone lentil or still lower in the 

Trinity formation. The deposits thus consist of asphaltic sand 

except at one place where the asphalt impregnates the Pike gravel 

member at the base of the formation. The layers containing the 

asphalt range from an inch to 12 feet in thickness.

LOCAL DETAILS 

PIKE

A deposit of asphaltic sand occurs on the west side of the PikeDelight highway, about 21/2 miles south-southeast of Pike, in the 

Caddo Gap quadrangle. It was worked from 1903 to 1906, inclusive,
158 DE QUEEN" AND CADDO GAP QUADRANGLES,- ARKANSAS

by the Arkansas Asphalt Co., and yielded 4,815 tons of asphaltic sand, 

valued at $22,368. A tram road about half a mile long conveyed the 

sand to the St. Louis, Iron Mountain & Southern Kailway (now the 

Missouri Pacific Railroad), whence it was shipped to Little Rock 

for use in paving streets. The old open cut out of which the sand 

was mined is 100 feet wide, 200 feet long, and 15 feet deep, and is in 

a depression which is drained eastward into Wolf Creek. The hills 

to the west and south show exposures of the Dierks limestone, but the 

beds in the cut consist chiefly of coarse sand, in some places rather 

calcareous, with beds of clay in the bottom of the cut. The sand is 

much cross-bedded and is incoherent except where charged with 

asphalt. The most productive part seems to have been at the north 

end, where some 4 feet of the base is asphaltic. The asphalt is 

not confined to any definite layer, the upper limit of it being very 

irregular. The only asphalt exposed in the south half of the cut in 

1908 was 8 to 12 inches thick, but beneath it was clay with thin 

streaks of more or less asphaltic material.

Hayes,95 who last visited the deposit in November, 1902, when the 

opening was new and not caved and not partly filled with water as at 

present described the deposit as follows:

The deposit is in the form of a sand stratum, which varies in thickness from 

6 to 12 feet, more or less thoroughly saturated with asphaltum. The deposit was 

discovered by the escape of small quantities of asphaltum to the surface in a 

spring, and this led to prospecting for its source. A pit was dug about 12 feet 

in depth, passing through the bed, and the thick, viscous asphalt has slowly 

oozed out into this pit for the last 30 years.

The asphaltic rocks show considerable variation in character and in the 

amount of asphaltum which they contain. * * *

By means of test borings the asphaltum bed has been proved to extend over 

a number of acres, under a cover sufficiently thin to permit profitable mining 

by stripping. * * *

The utilization of this deposit is a technical matter which can not be entered 

upon here. Its chief value will doubtless be as a paving material. As stated 

above, some portions of the bed form a natural paving mixture, which hardens 

on exposure to the sun and, so far as could be judged, would be fully as durable 

as the ordinary artificial mixtures made from Trinidad asphalt. Other portions are too rich to be used in a natural state. Tests of these portions in the 

preparation of a paving mixture have been made by the St. Louis Testing & 

Sampling Works, with excellent results. * * *

No'experiments have yet been made in refining the asphaltic sand for the 

preparation of pure asphaltum, and this may be found to be more profitable 

than shipping the crude product.

DELIGHT

An asphalt deposit that was prospected in 1914 by the GraysonMcLeod Lumber Co. lies in the head of a hollow about 4 miles north96 Hayes, C. W., Asphalt Deposits of Pike County, Ark.: U. S. Geol. Survey Bull. 213, 

pp. 253-254, 1903.
ECONOMIC GEOLOGY 159

northwest of Delight, just east of the highway, in the Caddo Gap 

quadrangle. A number of pits and cuts have been made, but at the 

time of visit (June 29, 1916) they had caved somewhat and were 

partly filled with water so that the asphalt bed could not be seen. 

Asphalt was found on the dumps of several openings for a distance 

of 175 feet down the hollow and was presumably thrown out of them. 

The other openings from which no asphalt was taken appear not to 

have extended deep enough to reach the asphaltic bed, which occupies a nearly horizontal position. About 10 feet of coarse quartz 

sand is exposed above the water in the openings. Above this there is 

20 to 25 feet of loose gravel extending to the crest of the ridge. 

Several feet of the gravel may have slipped down the slope and 

thereby concealed beds of sand higher than the sand exposed in the

openings. The gravel is the basal bed of the Tokio formation,

whose higher beds are exposed farther south near Delight but have 

here been removed through erosion. The sand belongs to the part of 

the Trinity formation that is above the Pike gravel member and below the Dierks limestone lentil. This limestone is exposed on Little 

Wolf Creek 2 miles farther south but is absent at the asphalt locality, 

as it is overlapped northward by the Tokio formation, at whose 

base there is, as previously stated, an unconformity.

The asphalt bed is said to range in thickness from 3 to 5 feet. 

Clay below the asphalt is said to contain seams of oil.

The asphalt on the dumps softens and flows in the sunshine, becomes plastic under the stroke of a hammer, is pliable in the hands, 

and adheres to the ringers. It contains quartz sand and a few 

nodules of iron pyrites. An analysis supplied by the GraysonMcLeod Lumber Co. shows the asphaltic sand to contain 17.21 per 

cent of the asphaltum and 82.80 per cent of white sand. Only sample 

lots have been shipped.

MURFKEESBOBO

A viscous asphalt impregnating a few inches or more of the Pike 

gravel member of the Trinity formation is exposed at the water's 

edge on the east side of Prairie Creek about 1 mile northeast of 

Murfreesboro in the Caddo Gap quadrangle. The thickness and 

extent of the deposit are not known.

Asphalt several feet thick is said to have been found in digging a 

well on the Irving farm, in sec. 1, T. 8 S., R. 25 W., 5 miles east of 

Murfreesboro. It affected the water to such an extent that the well 

has since been converted into a cistern.

LEBANON

Asphaltic sand is exposed by the roadside on a low hill adjoining the Saline River bo.ttom half a miJe southeast of Lebanon, in the
160 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

De Queen quadrangle. It occurs in lenticular layers, the thickest 

of which is only a foot thick. It is much weathered in the exposures, 

being dark brown and falling to a powder when struck with a hammer, but it becomes viscous when heated with a match. The asphalt 

impregnates sand which is below the Dierks limestone exposed to 

the southwest south of Woolsey School and which, as shown in the 

following section at this locality, overlies the Pike gravel:

Partial section of Trinity -formation half a\ mile southeast of Lebanon

Feet

 Yellow sand partly concealed by surficial gravel extends to 

the top of the hill. A 2 or 3-inch layer of asphaltic sand 

is 3 or 4 feet above the base of this bed of sand______ 12-25 

Yellow sand, lenticular layers of which are impregnated

with asphalt. The thickest layer is 12 inches thick_____ 2-3 

Gray and yellow sand, some of which is indurated 5 

Gravel with pebbly sand in its upper part. The1 exposure 

extends down to the edge of the second bottom of Saline 

River (Pike gravel)___ ______ ___ 16

Asphaltic sand is exposed in a gully by the roadside at the foot 

of a hill about 2,y2 miles west-southwest of Lebanon, apparently in 

the southeast corner of sec. 1, T. 8 S., K. 30 W. This sand ,is much 

weathered, being brown and friable, and is in two layers each 1 inch 

thick, which are separated by aj few inches of sand and are overlain 

and underlain by sand. The sand containing the asphalt appears 

to be between the Pike gravel and the Dierks limestone.

Sand impregnated w.ith asphalt is exposed on the south side of the 

road half a mile east of Sardis School and 4 miles west-southwest of 

Lebanon. The asphalt here also is much weathered and is brown and

friabje. The following section was measured up the hill southwest

of the deposit:

Section 4 miles west-soutlnvest of Leba/non

Feet

Terrace deposits: Gravel and cobbles occupying crest of hill. 

The thickness of the gravel bed is less than 35 feet, for the 

gravel has probably slipped down the slope, thus concealing 

beds of the Trinity formation_________ ____ 35 

Trinity formation:

Dierks limestone lentil 

Red and yellow clay containing some pieces of limestone________________,___________ 12

Platy limestone containing fossil oyster shells___ 4-5 

Gray compact sand_ _ _ __ 6 

Sand impregnated with asphalt, a few inches. 

Gray compact sand___ _ __ ___ 1%

Asphaltic sand is revealed in a shallow pit by a road leading up 

the hill just northwest of Moody Shoal Ford, on Cossatot R.iver
ECONOMIC GEOLOGY 161

miles west-southwest of Lebanon. The following section was 

measured here:

Section west of Moody Shoal Ford, 6^ miles southwest of Lebanon

Feet

Terrace deposits: Gravel and cobbles. The thickness is 

probably less than 55 feet, as some of the gravel and cobbles have doubtless slipped down the slope and thus conceal beds of the Trinity formation____________ _ 55 

Trinity formation:

Dierks limestone lentil 

Red clay ____________________-____ 2 

Limestone containing fossil oyster shells -_____ 1 

Clay __ __, __. 5 

Asphaltic sand. A limestone layer 1% inches thick ,

was found in the base_ 2% 

Red clay _____________________________ 10

VALUE OF DEPOSITS

The asphalt deposit near Pike is the only one from which asphalt 

has been shipped in commercial quantity. The asphaltic sand mined 

at that locality from 1903 to 1906 by the Arkansas Asphalt Co. 

is said to have amounted to 4,815 tons, vajued at $22,368. It was 

used ,in Little Rock in paving West Markham Street from Main to 

Cross Street, a distance of 12 blocks, and in paving part of Center 

Street. A 2-inch surface of the. asphalt was laid upon a 5-inch 

concrete base, which rested upon clay. Owing to improper preparation of the asphalt the paving was not entirely satisfactory.

The asphalt deposit near Delight is thin, the reported thickness 

being 3 to 6 feet. If the deposit is later proved to maintain that 

thickness under a considerable area, it might be profitably worked, 

but the overburden is so thick, 30 to 35 feet or more, that underground mining would probably be necessary. The asphalt exposed 

at the other localities is not thick enough to be mined and probably 

is no thicker away from the outcrops.

ORIGIN OF THE ASPHALT AND POSSIBILITY OF OIL AND GAS IN THE

QUADRANGLES

The Trinity formation contains petroleum and asphalt at many 

places in northern Texas and southeastern Oklahoma. The asphalt 

in these two States and in Arkansas, as in other regions, is doubtless 

a residue of crude petroleum, whose lighter and more volatile parts 

have escaped by evaporation. The petroleum yielding the asphalt 

in Arkansas may have originated in the basal part of the Trinity 

formation, which contains some fossiliferous limestone:

On the assumption that the petroleum yielding the asphalt herein 

described originated in the Trinity the petroleum has probably mi-
162 DE QUEEN" AND CADDO GAP QUADRANGLES, ARKANSAS

grated northward. The Cretaceous rocks in southwestern Arkansas 

have a southward dip of about 100 feet to the mile and, although 

they have been slightly warped, no pronounced anticlines or synclines 

occur in these rocks in the quadrangles under discussion. Thus, if 

petroleum; occurs in the region south of the asphalt deposits, its accumulation into quantities of possible commercial importance would 

probably be controlled by terrace structure, lenticular character of 

sands, or irregularities in the Cretaceous floor.

The peridotite masses near Murfreesboro may have lifted the 

Trinity so as to produce structure favorable for the accumulation of 

oil about them, just as volcanic necks or plugs have done in Mexico 

and probably in Texas, but such phenomena have not been observed 

around the peridotite masses.

There is no possibility that either oil in commercial quantities or 

gas in large pools will be found in the Ouachita Mountain region of 

west-central Arkansas or in most of this region in Oklahoma. The 

Carboniferous and older rocks have been so highly tilted and so much 

fractured and metamorphosed that if oil or gas were ever present in 

them the gas and much of the oil would have made their escape to 

the surface and the remainder of the oil would have been distilled 

to asphalt.

DRILLING FOR OIL

The presence of asphalt in the southern parts of these quadrangles 

has from time to time attracted the attention of those interested in 

oil development. Land has been leased at different times, and a few 

wells have been sunk with the hope of finding oil. Thus fw oil has 

not been discovered in commercial quantity.

TRIPOLI

Tripoli deposits were examined at four localities during the field 

work for this report. The tripoli at two of the localities is a weathered phase of the upper division of the Arkansas novaculite, that 

at the third represents a similar phase of the lower division of the 

novaculite, and that at the fourth is in the Bigfork chert. The 

deposits have apparently been formed not merely through the removal by solution of the small quantity of calcium carbonate that 

was originally present in these rocks but through a recrystallization 

of the silica. Other occurrences of tripoli may be expected in the 

Arkansas novaculite, especially in its upper division, which is exposed in many narrow, nearly eastward-trending belts in the 

northern parts of the quadrangles.

Three of the deposits have been prospected, and two of them have 

furnished a small quantity of tripoli, which has been sold. The 

available quantity is great at some places, and the quality appears to 

be good. If there should be an increased demand for tripoli in
ECONOMIC GEOLOGY 163

the future some of the deposits may then be worked on an extensive 

scale.

One deposit is at the south base of the easternmost of the three 

mountains in this area called Fodderstack Mountain, 7 miles west 

of the village of Caddo Gap. It appears to be in and near the top of 

the lower division of the Arkansas novaculite, which at this locality 

is nearly horizontal and lies near the axis of a syncline. The deposit 

at the time of visit (1916) was exposed.in two cuts. The longer one, 

50 feet long, is on the north edge of the bed of a dry branch which 

flows east along the base of the mountain, and the cut extends 

into the mountain about 10 feet. The following section of the 

Arkansas novaculite was measured in it:

Section of rocks m cut at south base of Fodderstack Mountain

Ft. in.

Face of d6bris, above which the mountain slopes 30° toward 

the south __________ _ __________ __ 5

Hard, white, much jointed novaculite______________ 4 

Pure white tripoli; not iron stained except along a few of

the joints_____________________________ 2 

White tripoli containing in places a large quantity of hard, 

white novaculite; the bed is much shattered and shows 

iron oxide along the joints and some disseminated through 

the tripoli. This bed may be freer of iron oxide farther 

back into thei mountain_ ______ ___ 1 2

Plastic yellow clay____________________ __ 2 J/> 

Hard, white novaculite____________________ 3 

Pure white tripoli_________________________ 1

Pure white tripoli containing hard pieces of novaculite 3 

Concealed to bed of dry branch_____________ 2

The other cut at the base of Fodderstack Mountain is 60 feet west 

of the cut above described and is on the north side of the dry branch. 

Here a thickness of 6 feet of shattered, altered novaculite is exposed. 

Although most of the novaculite is hard, it has softened to tripoli in 

several layers a few inches thick. The tripoli is yellow from iron 

oxide, but it may become whiter with depth from the surface.

To mine more than a very small quantity of tripoli at this locality 

would require underground mining, because of the nearly horizontal 

position of the tripoli beds and of the steepness of the mountain 

slope; but the thickness and extent of the deposit as shown in the 

cuts probably would not justify opening a mine. Further prospecting, however, may prove the presence of a deposit large enough to be 

worked at a profit. Much of the tripoli in the larger cut is firm and 

would require grinding to reduce it to a powder. Some of it might 

be suitable for filter stones, but it would probably yield only small 

filter stones, as it is much jointed. It is suitable for polishing powders. After it is ground it passes through a sieve of 150 meshes to 

the inch. It consists of sharp quartz grains from 0.01 to less than
164 DB QUEEN AND CADDO GAP QTJADBANGLES, ARKANSAS

0.001 millimeter in diameter; most of the grains are 0.005 millimeter 

or less. A few hundred pounds of this tripoli has been shipped for 

use as polishing powder.

A similar tripoli deposit, apparently near this locality, is described 

by Griswold,96 who gives the following analysis of the tripoli described 

by him:

Analysis of tripoli from Fodderstack Mountain 

[Material dried at 110°-115° C. Analysis by Arkansas Geol. Survey]

Silica (Si02 ) ___________________________ 97.32

Alumina (A12O3 )_________________________ 1.61

Ferric oxide (Fe2<)s) __________________ .35

Lime (CaO)___ ___________________ Trace. 

Magnesia (MgO) ________________ Slight trace.

Potash (KaO) _________________________ . 13

Soda (Na2O) __________________________ .12

Loss on ignition ____ __ _ . 63

100.16 

Water at 110°-115°C______________________ .029

A deposit of tripoli in the Bigfork chert is exposed in a small cut 

at the south base of a low hill half a mile southwest of the village of 

Caddo Gap. The Bigfork chert at this locality is closely crumpled 

and much shattered and in parts has altered to tripoli. Some tripoli 

is mixed with broken fragments of chert in most parts of the exposure. The largest mass of tripoli free of chert fragments is 5y2 

feet wide and several feet high, but the exposure is not sufficient to 

show the horizontal extent. Fully half of the tripoli is stained yellow with iron oxide; the rest is white. It is composed of angular 

quartz grains 0,05 to less than 0.001 millimeter in diameter, few

exceeding 0.005 millimeter. As the tripoli readily slacks in water 

and is slightly plastic, it probably contains a small percentage of 

clay. After it is subjected to slight grinding practically all passes 

through a sieve with 100 meshes to the inch and a large portion 

passes through a sieve with 150 meshes to the inch.

A deposit of tripoli occurs one-fourth mile east of Blocker Creek, in 

sec. 1, T. 5 S., R. 27 W., 2^ miles north-northeast of Langley, in the 

Caddo Gap quadrangle. It was worked in 1914 and 1915 by the 

W. C. Ross Manufacturing Co., of Little Rock, which shipped two 

carloads of the tripoli and stored a large quantity of it in a shed to 

dry before shipping. The workings consist of an east-west cut, with 

u face of 15 or 16 feet and length of 70 feet, on the north side of a 

westward flowing wet-weather branch. The rocks exposed in the top 

part of the cut consist of a bed of pebbles and cobbles of novaculite

98 Griswold, L. S., Whetstones and the Novaculities of Arkansas: Arkansas Geol. Survey 

Ann. Kept, for 1890, vol. 3, pp. 384-388, 1892.
ECONOMIC GEOLOGY 165

that underlie a stream flat, and below this bed is the upper division 

of the Arkansas novaculite, which dips 10 feet toward the west in 

the length of the cut. The novaculite at this locality lies in a 

syncline that plunges or deepens toward the west. The following 

section was measured in the cut:

Section in cut in tripoU 2% miles north-northeast of Langley

Feet 

Pebbles and cobbles of novaculite underlying narrow stream

flat ________________________________ 3-5 

Arkansas novaculite:

Hard jointed novaculite interbedded with a less quantity 

of yellow tripoli. This bed thins out in the east end of 

the cut___________________________ 0-4 

Tripoli bed described below ___ _ _ 8^ 

Thin layers of hard yellow novaculite interbedded with 

an equal quantity of yellow tripoli in thin layers _ 12

The 8^-foot bed of tripoli included in the above section has yielded 

the two carloads of tripoli that have been shipped and the tripoli that 

has been stored. Except for two layers, each 6 to 8 inches thick, 

of hard novaculite near the middle of the bed, it consists 'of eventextured tripoli about half of which is snow-white and the other half 

light cream-colored. The bed is cut by joints, which are most abundant at the east end of the cut. The tripoli in the shed ranges from 

particles as fine as flour to boulders as much as 18 inches in their 

longest dimension. Although the tripoli is tough it is easily reduced 

to a fine powder, consisting of angular quartz grains from 0.01 to 

0.001 millimeter in diameter; the average size is about 0.005 millimeter. After it is slightly ground it passes through a sieve with 10G 

meshes to the inch, and about half of it passes through a sieve with 

150 meshes to the inch. It is suitable for polishing powder, but the 

rock may not be tough enough for the manufacture of filter stones. 

The tripoli apparently underlies at least 2 acres north and west of 

the cut, where the overburden is thin enough for open-cut mining.

A deposit of tripoli is exposed in and near the wagon road at the 

east base of a hill in the southwestern part of the village of Bog 

Springs, in the De Queen quadrangle. The exposure reveals 20 feet 

of tripoli in the upper division of the Arkansas novaculite, and it 

does not show either the base or top of the tripoli. The tripoli is 

in beds from a few inches to 18 inches thick and is cut by joints 3 to 

20 inches apart. Only one or two layers of hard novaculite were 

observed. The rest of the tripoli, though soft, is tough enough to 

receive the impressions of a hammer without breaking. Much of it, 

even at the surface, is white after the iron-stained portions along the 

joints are removed, but some of it is cream-colored, and one layer a 

few inches thick contains stains of manganiferous iron oxide. It con6242 29 12
166 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

sists of angular quartz grains which range from 0.02 to 0.001 millimeter in diameter, but most of which are about 0.005 millimeter in 

diameter. It is sufficiently hard and tough for shaping into filter 

blocks, though it has not been tested, so far as known. Crushing and 

grinding would be required to reduce the tripoli to a powder fine 

enough to pass through a sieve of 100 meshes to the inch.

LEAD AND ZINC DEPOSITS

GENERAL FEATURES

Two mines, the Bellah and Davis, have been worked from time to 

time in the De Queen quadrangle and have produced small quantities 

of lead and zinc ores, and a few prospects in this quadrangle have 

been opened in search of these ores. The ore deposits occupy fissure 

veins associated with quartz in steeply dipping sandstone and shale 

of Carboniferous age, and there is evidence of faulting along some of 

the veins. The ore minerals are sphalerite and galena, and the associated minerals besides quartz are chalcopyrite, pyrite, siderite, calcite, azurite, and malachite, the last two, occurring only near the 

surface.' The occurrence of the ores in faulted fissure veins combined 

with their nearness to the antimony deposits near Gillham, which in 

origin are probably related to igneous rocks, suggests that the lead 

and zinc ores were also similarly related.

Some of the lead and zinc deposits in the De Queen quadrangle 

can probably be worked spasmodically in the future, just as they 

have been in the past, but the known deposits are comparatively small 

and hence are not capable of a large production of ores.

BELLAH MINE

The Bellah mine is in sees. 27 and 28, T. 7 S., K. 32 W., about 6 

miles southwest of Gillham, in the northwest corner of Sevier County. 

It was idle and was filled with water at the time of the field examination by the authors, and the description of it given herewith 

is abstracted largely from .the report by Bain,97 who visited the mine 

many years ago, and from field notes by D. F. Hewett, who 

entered the mine in 1912.

The mine was worked during the Civil War by the Confederate 

government for lead, but since then it has been operated at times as 

a zinc mine. The slag and furnace remains indicate that work at 

that early date was carried on for some time. The owners of the 

mine in 1912 were Tyler & Hippach, and the lessees .were Sober, 

Williford & Lynn, who reopened the mine and operated it for several 

months before the fall of 1912.

97 Bain, H. F., Preliminary Report on the Lead and Zinc Deposits of the Ozark Region: 

U. S. Geol. Survey Twenty-second Ann. Rept., pt. 2, p. 133, .1901.
ECONOMIC GEOLOGY 16?

The workings consist of a shaft 165 feet deep with drifts to tho 

east at depths of 44, 115, and 165 feet; an air shaft 44 feet deep; 

and a third shaft 115 feet deep. When the mine is idle water stands 

at the 115-foot level. The shafts and a few pits have been made at 

places along the length of the ore body for a distance of about 1,000 

feet.

The country rock is the Stanley shale, and the part of the formation occurring in the vicinity of the mine is a bluish-black clay shale. 

The ore body occurs in a zone with a maximum width of 8 feet, in 

which there are irregular fractures filled with quartz. The zone 

strikes N. 80° E. and is practically vertical at the surface, but at 

moderate depth it dips 60°-70° N. The hanging wall of the zone is 

well defined, as it is marked by a clay selvage. It has striations with 

a dip of 15° E., showing that there has been faulting with both a

vertical and a horizontal component. White massive quartz, which 

constitutes much of the zone, carries abundant sharp-angled pieces of 

the country rock, but some of the quartz occurs in small crystals 

lining the vugs and druses in the vein and in streaks and bands running through the zone. It is arranged with the ore in ribbon structure, though there is no uniform sequence for the cleposit as a whole. 

The metallic minerals that are associated with the quartz are sphalerite, galena, chalcopyrite, and pyrite. Galena was the most abundant 

ore above the 44-foot level, but at present at and below the 115-foot 

level sphalerite of a rosin-yellow color is the most abundant. With 

it are minor quantities of galena and chalcopyrite, and negligible 

quantities of pyrite. Some of the chalcopyrite has yielded a little 

.azurite and malachite, especially near the surface. Associated with 

the quartz is a small quantity of siderite. The exact order of deposition of all the minerals is not known, but to judge from material on 

the dump the sphalerite, chalcopyrite, galena, and pyrite followed at 

least most of the quartz and siderite.

The ore-bearing zone has been partly stoped east of the 165-foot 

shaft above the 44-foot level. It has also been stoped .for a distance 

of 60 to 80 feet from this shaft above the 115-foot level, though no 

 connection has been made with the 44-foot level. The workings on 

the 115-foot level extend from this shaft a distance of 200 feet.

The ore that has been milled is said to have yielded 21 per cent of 

zinc sulphide, and the ore sold is said to have contained 60 per cent 

or more of metallic zinc.

DAVES MINE

The Davis mine is in the NW. % sec. 10, T. 7 S., E. 32 W., 4 miles 

west-southwest of Mineral, on the Kansas City Southern Railway, 

in the northwest corner of Sevier County. It is reported that Julius 

Tolsom, a Choctaw chief, opened the mine in 1842, and that a zinc
168 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

smelter was erected at the mine in 1875 or 1876. Sam Davis worked 

the mine in the eighties and sold it about 1900 to the Southern 

Zinc Copper Mining Co. Thi,s company, which operated the mine 

for six years ending in 1906, produced both lead and zinc ores, which 

were hauled to Mineral for shipment. During the period of greatest 

production the shipments averaged one carload of ore every week. 

In 1911 and 1912 the mine was worked by Karl Shuey, who shipped 

15 or 16 carloads of ore, half of it sphalerite and the other half 

galena. The mine was next worked by A. V. Oliver, beginning in 

March, 1916, and then by the Boston & Arkansas Mining Co., of 

Okmulgee, Okla.

The workings at the time of visit (1916) consisted of four shafts 

from which several drifts had been run. The deepest shaft is said 

to have been 204 feet deep.

The rocks at this locality are black shale and hard gray sandstone, 

which are a part of the formation known as the Stanley shale. They 

dip 50° or more to the north, and they have been cut by two or more 

faults, as is indicated by the presence of smooth slickensided planes 

with steep dips. The fault farthest south dips' about 60° N. and 

strikes N. 85° E. 'The shale and sandstone above this fault are much 

fractured and crumpled and contain quartz veins through a zone as 

much as 40 feet wide.

The quartz veins in this zone, especially those adjacent to the footwall, carry sphalerite, galena, chalcopyrite, and calcite, the most 

abundant named first. In addition there are small quantities of 

azurite and malachite near the surface, and small quantities of calamine were reported to be present at some places. The sphalerite, 

galena, and chalcopyrite are more or less intermixed; they occur as 

single crystals and aggregates of crystals disseminated through the 

quartz veins and as solid veins, some of which cut through quartzite 

without quartz. Assays of specimens of these minerals that have 

been made by the Arkansas Geological Survey showed the presence 

of a trace of gold and from 17.5 to 31 ounces of silver to the ton.98

The workings at the time of visit appeared to show that the deposit 

has a length of at least 300 feet, a width of as much as 30 to 40 feet, 

and a depth of 204 feet, which is said to be the depth of the deepest 

shaft.

PROSPECTS

The Copper King prospect is in the W. y2 sec. 8, T. 7 S., K. 32 W., 

2 miles west of the Davis mine and 6% miles west of Gillham. Work 

was done at this locality many years ago, and so far as the authors are 

aware no ore from the mine was ever sold.

68 Comstock, T. B., Report upon Preliminary Examination of the Geology of Western 

Central Arkansas: Arkansas Geol. Survey Ann. Rept. for 1888, vol. 2, pp. 233, 252, 1888.
ECONOMIC GEOLOGY 169

The openings include an east-west cut on the right bank of Robinson Creek, having a length of 36 feet and a face of 12 to 15 feet, an 

inclined shaft 12 to 14 feet deep at the west end of the cut, two shallow 

pits east of the cut, and a short north-south cut and an incline which 

.are 150 feet west of the east-west cut, on the hill slope 75 feet above 

the creek.

The rocks penetrated by the openings are a hard gray sandstone 

that has a dip of 45° or more toward the north and strikes N. 80° W. 

Some beds of the sandstone have been much fractured and contain 

many quartz veins, most of which are less than 1 inch wide, though 

xi quartz vein 3 feet wide was seen at one place. Quartz is the only 

mineral that was seen in place, but a few small specimens of it containing calcite, chalcopyrite, azurite, and malachite were found on

the dump.

The Buzbee prospect is near the center of sec. 13, T. 7 S., R. 29 

W., about 2% miles northwest of Dierks. Work has been carried 

on here from time to time, beginning in 1850, but no ore is known 

to have been sold. The country rock is the Jackfork sandstone, 

which dips 65° N. 20° W. The deepest of the three shafts is a little 

more than 80 feet deep and was driven down in a 5-foot bed of 

. brecciated sandstone whose fragments are cemented together with 

quartz. A second shaft was sunk into a bed of shale 3% feet thick. 

The third shaft was not visited by the authors. A small pile of 

rock lying near the first shaft and apparently taken from it shows 

a small quantity of sphalerite of a rosin-yellow color, with still 

smaller quantities of galena and chalcopyrite.

The New Discovery shaft is in the SE. % sec. 6, T. 7 S., R. 30 W., 

about 5 miles east and a little north of Gillham, in the vicinity of the 

antimony mines. The shaft, which is said to be between 100 and 

125 feet deep, was sunk in 1902. None of the geologists who have 

visited the region have entered this shaft, and the vein is not visible 

at the surface. To judge from a small amount of ore in the bin 

it is a brecciated sandstone which is cemented with small veins containing sphalerite, galena, quartz, and siderite. There are also small 

amounts of pyrites, which may be copper bearing. Only one piece 

showing stibnite was found, and that it came from this shaft is not 

certain. The ore bears little resemblance to that from the antimonybearing veins, and the amount of quartz is very much less. It is 

said that no ore has been shipped from this property.

There is a lead-zinc prospect three-quarters of a mile northeast of 

Vandervoort, on the Kansas City Southern Railway, in the southern 

part of Polk County. A shaft was sunk here about 35 years ago, 

and another was sunk in 1916, 20 feet east of the old shaft. The 

old shaft had caved before the time of visit (July, 1916), and the
170 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

new shaft was then filled with water. The rocks penetrated by the 

shafts are shale and sandstone, which are a part of the Stanley 

shale. The fragments of these rocks on the dumps contain veins 

of quartz and calcite as much as several inches wide. A small 

quantity of galena and sphalerite was found associated with these 

vein minerals.

MANGANESE ORE

Only the general geologic and economic relations of the manganese deposits will be discussed here, for detailed descriptions of 

them have been given in another report by Mr. Miser."

The manganese deposits occur in the mountainous parts of the 

quadrangles. They are found in the Arkansas novaculite and are 

mainly confined to two stratigraphic horizons, one in the upper division of the formation and the other near the top of the lower division. 

Some deposits, however, are found in other parts of the lower division. The Arkansas novaculite and other formations have been 

thrown into a series of folds whose trend is parallel with the ridges. 

This formation is very resistant; the upturned edges stand up as 

ridges on which rock ledges or their debris abound. The beds at 

the two ore horizons, which show ore at the surface in many places, 

may thus be followed for long distances along the slopes, and their 

outcrops, owing to the numerous folds, are repeated on the slopes 

or crests of the many parallel ridges, or even on a single ridge. The 

outcrops of these ore-bearing beds are sometimes called "lodes" 

or " leads."

The depth to which the ore extends is not known. An 8-foot vein 

of solid manganese ore is, however, reported to have been found 

in the lower tunnel at the North Mountain mine at a distance of 

about 615 feet from the portal. This tunnel is 250 feet above the 

road along the south base of North Mountain; it is 530 feet below the 

crest of the mountain and is 216 feet below the upper tunnel, which 

penetrates the exposed ore body near its main outcrops. At other 

places ore is found only in the present shallow workings. These 

workings and the outcrops of ore occur at all altitudes on the high 

ridges, from the level of the streams that cut through them up to 

their crests, which are even and probably represent a Cretaceous 

peneplain. The deposits that have been examined range from 900 to 

1,800 feet above sea level, but the greatest difference in altitude in 

any single locality is about 800 feet. This range does not necessarily 

mean that a shaft sunk from the crest of a mountain would find ore 

at a depth of 800 feet or that a tunnel driven into the base of a mountain 800 feet below its crest would find ore, for the lower limit of the

"Miser, H. D., Manganese Deposits of the Caddo Gap and De Queen Quadrangles, 

Arkansas: U. S. Geol. Survey Bull. 660, pp. 59-122, 1917.
ECONOMIC GEOLOGY 171

ore, which may not extend much below water level, may be higher in 

the mountains than in the valleys, just as the water level is higher: 

in the mountains than in the valleys.

The manganese ores occur as nodules, pockets, and short irregular 

veins from a fraction of an inch to 4 feet thick. Thicknesses of 4r 

feet, however, are rare, and those of 1 foot are not common. The 

ore bodies are scattered through the hard novaculite and can doubtless be found on every mountain where the Arkansas novaculite is 

exposed. The ores occupy bedding planes or joint cracks or form a 

cement in a novaculite breccia, in which the rock fragments range 

from a fraction of an inch to over a foot in diameter. Iron and 

manganese ores may be intimately mixed in the same pocket 01 

vein, they may occur separately in different parts of the same vein, 

or they may occur in separate masses.

The manganese ores consist of oxides, four of which, psilomelane. 

pyrolusite, manganite, and wad, have been identified; if others are 

present, they probably occur in minute quantities. Although these 

minerals may be found separately, as a rule two or more are intimately 

mixed in the same deposit, and in some places they are associated with 

iron ores and manganiferous iron ores. Psilomelane, pyrolusite, and 

manganite form the larger part of the manganese ore in this region.. 

A material consisting of rock fragments and clay cemented together 

by soft manganese oxide is present at a number of places; locally it is 

known as "bog ore." The iron ores comprise various hydrous sesquioxides, of which limonite is probably the most common. The most 

abundant material with which the iron and manganese ores are associated is clay, some of which has been brought in by ground water 

and some of which is residual and probably in place.

The mode of occurrence of the manganese ores in the Arkansas, 

novaculite suggests that their origin and that of the novaculite are 

intimately associated. The novaculite is regarded by the writers and 

some others as having been deposited through chemical or organic 

processes, or both, and thus belonging to the class of cherts. The 

manganese was probably deposited as a manganese-bearing calcite 

at the two main ore horizons, but some of it was doubtless deposited 

as a carbonate in other parts of the novaculite and in the overlying 

and underlying shales.

The concentration of the ores has been effected by ground water, 

which has carried down their constituents from the vast mass of 

rock that has been eroded from the region. The local concentration' 

of the ores into deposits large enough to be of value appears to 

have been dependent upon the amount of open space in the Arkansas 

novaculite, which is hard and compact and usually has no visible 

openings between the layers or along the joints. The places where
172 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

fissures are largest and most numerous would be most favorable for 

the circulation of underground water and consequently for the deposition of the ore, little of which replaces the novaculite. The fissures 

were forme°d during the folding, faulting, and fracturing of the 

novaculite late in the Carboniferous period. The ores would be expected to occur in those places where the novaculite has undergone 

much fracturing and close folding, as on and near faults and at the 

noses or ends of plunging anticlines. A number of such places 

where deposits occur have been observed. It is noteworthy that many 

cold springs and even the hot springs at Hot Springs, Ark., issue on 

the noses of plunging anticlines, showing that such places are especially favorable for the circulation of ground water.

The following are analyses of manganese and manganiferous iron 

ores from these quadrangles:

Analyses of manganese and manganiferous iron ores from the Caddo Gap and 

De Queen quadrangles, Ark.

Silica (SiOs) ...... ...........

1

60.28

.413

Iron (.Fe)--..._._ _ ........

Silica (Si02)-. .- - .

Iron (Fe)._...... ............

Silica (SiOa)... ........ ..

Sulphur (S) .-.. . ..... ..

2

58.36

9.02

10

22.84

.42 

.047

18

42. 75 

2.72 

10.46 

.450 

62.75

3

55.80 

.50

3.72

.038

11

11.93 

22.26 

44.40 

.576

19

59.55 

.74 

.52 

None. 

90.52

4

51.54

.167

12

2.06 

50.38

1. 450

20

25. 99 

10.75 

5.21 

.387

8.44 

.04 

.04 

.024 

16.04

5

48.65 

2.03 

11.86

.308

13

30.93 

9.21 

5.86 

.320 

42.09

21

30. 95 

12.80 

6.20 

.461

16.04 

.05 

-.05 

.029

0

48.34

.449

14

48.02 

5.55 

.52 

.310 

71.73

22

16.45 

5.11 

17.16 

.181

8.62 

.04 

.04 

.028 

31.35

7

40.51 

25. 53 

.80 

.767

15

56.66 

.18 

.15 

Trace. 

82.10

23

23.96 

7.45 

25. 00 

.264

12. 55 

.06 

.06 

.041

8

27.68 

35.39 

1.88 

.230

16

49.24 

2.04 

2.98 

.380 

71.41

24

60.54

8.30 

.22

........

9

26.20 

16.83 

29.00 

.343

17

52.16 

4.00 

.24 

.390 

77.60

25

43.52 

6.72 

»5.17 

.35 

(») 

4.80 

1.42 

Trace. 

.02

Silica and insoluble in HC1. & Oxidizing power equal to 64.60 per cent MnOs.

Analyses 1 to 12 from Age of Steel, vol. 62, p. 9, Sept. 3, 1887; 13 to 19 from Penrose, R. A. F., jr., 

Manganese Its Uses, Ores, and Deposits: Arkansas Qeol. Survey Ann. Eept. for 1890, vol. 1, p. 319,1891; 

20 to 23'furnished by Mississippi Valley Iron Co.; 24 furnished by Dierks Lumber & Coal Co. Analysts: 1, 4, 6,12, Regis Chauvenet & Bro.; 2, 3, 5, 7-11, St. Louis Sampling & Testing Works; 13-19, R. N. 

Brackett; 24, Kansas City Testing Laboratory; 25, George Steiger.

1-12. Polk County, locality unspecified.

13. Line Mountain, Pike County.

14. Fancy Hill Mountain [W. R. Porter prospect], Montgomery County.

15. North Mountain [mine], Montgomery County.

16. McKinley Mountain, Polk County.

17. Tall Peak Mountain, Polk County.

18. Manganese Mountain, Polk County.

19. Cossatot Mountain, Polk County.

20-23. Still mine, Pike County. 20, One car, natural; 21, same, dry; 22, another car, natural; 23, same, 

dry.

24. Dierks Lumber & Coal Co.'s prospect, Montgomery County.

25. Composite sample from 30 localities in Pike, Polk, and Montgomery Counties..
ECONOMIC GEOLOGY ' 173

The possibilities of manganese mining in west-central Arkansas 

are ably discussed by Penrose,1 from whom the following is quoted:

The aggregate amount of manganese in the region is undoubtedly large, 

but it is distributed over an extensive area, aud in almost all places it is hopelessly scattered through the rock in small nests and seams. If these nests 

and seams were in sufficient quantities the rock might be crushed and the ore 

concentrated by washing, but the pockets containing them are too sinall to 

permit the expense of machinery. It is a popular idea that the ore will increase in quantity at a depth, but there is absolutely no reason to expect this, 

as such deposits are just as likely and sometimes even more likely to become 

poorer at a depth than they are to improve.

From the nature of the deposit it is to be expected that the ore at a depth 

is, at the very best, no more plentiful than in the surface outcrops of the so-called 

" lodes " that is, that it exists as a series of pockets separated by greater o>r 

less distances of barren rock. With very few exceptions the pockets of ore 

seen on the surface can not be worked at a profit, and in the rare cases 

where a small profit might be made the amount would not be enough to pay 

for sinking through the barren rock that separates the pockets from each 

other. The intervening thickness of barren rock is much greater than the 

depth of any one pocket.

The quantity of manganese ore that can be mined at a profit from 

an}' one deposit is therefore small, which means that under normal 

conditions manganese mining will never become one of the chief 

industries in this region.

The manganese deposits have been worked only in a very small 

way and so far have yielded not more than a few hundred tons of 

ore that has been sold. Most of the work has been done during two 

periods of activity, one beginning about 1885 and ending in 1889, 

and the other beginning in 1915 and still in progress. The geologic 

map (pi. 3) shows the location of many of the prospects and mines.

IRON ORE

Iron oxides, of which the most common is probably limonite, are 

found in many parts of the quadrangles, but the,. deposits that are 

largest and that have at times attracted the attention of prospectors 

occur in the Arkansas novaculite in the mountainous areas. Most 

of the deposits are confined to the upper division of the formation 

and the upper part of the lower division. They occur as pockets, 

seams, or veins along the bedding and along joints, and in places 

they cement together fragments of brecciated novaculite. They 

have been concentrated by descending ground water, and their 

source is probably pyrite, which occurs as small crystals disseminated 

through the unweathered novaculite. In some places the iron ores 

are free of manganese, but in others there are all gradations from

1 Penrose, R. A. F., jr., Manganese Its Uses, Ores, and Deposits: Arkansas Geol. Survey 

Ann. Kept, for 1890, vol. 1, p. 306, 1891.
174 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

an iron ore with a little manganese to a manganese ore with a little 

iron.

The iron ores are usually too low in iron and too high in silica 

to be of commercial value, and where the quality is above the average the quantity of the ore is too small to permit profitable mining. 

Some of the ores contain too much phosphorus to command a high 

price. Moreover, the ores are associated with hard rocks, which 

stand vertical or almost vertical.

Further information on these deposits may be obtained by referring to Penrose's report,2 from which much of the foregoing statement is abstracted.

QUARTZ CRYSTALS

Quartz crystals have been found at a number of places in the 

Crystal Mountains, in the Caddo Gap quadrangle. They occur in 

beautiful clusters that line the walls of pockets and cracks along 

the bedding and joint planes of the Crystal Mountain standstone. 

Some of the crystals are milky, owing to small air cavities, but many 

are perfectly clear. (See pi. 17, B.) They have been mined on a 

small scale from time to ^tinie on the head of Collier Creek and at 

other places. The mining has been done by means of pits and short 

irregular tunnels. After the crystals are mined they are freed from 

<;lay and are washed with oxalic acid to remove any coatings of iron 

and manganese oxides that may be present. They are sold as specimens for private and public mineral collections, but some are cut and 

sold for jewelry, and some are used in optical instruments. Supplies of crystals are kept for sale at Hot Springs and Womble.

GYPSUM

The gypsum deposits of these quadrangles are found in the De 

Queen limestone member of the Trinity formation. The thickest 

exposure is in Plaster Bluff, 3 miles south-southwest of Murfreesboro, where the gypsum is confined to a single bed oo feet above 

Little Missouri Eiver and about as far below the top of the bluff. 

This bed is 10 to 14 feet thick and consists of pure saccharoidal 

gypsum, though there are some thin seams of satin spar and as much 

as 3 feet of interbedded clay in its lower part. The thickest layer of 

gypsum is at the top and is 4 feet thick. The deposit at this locality 

has been worked on a small scale, especially by the National Gypsum 

Co. in 1922 and 1923. The gypsum sold by this company was used 

in the manufacture of cement.

2 Penrose, R. A. F., jr., The Iron Deposits of Arkansas: Arkansas Geol. Survey Ann. 

Kept, for 1892; vol. 1, 1892.
ECONOMIC GEOLOGY 175

Toward the west as far as Messer Creek, on the west side of the 

Caddo Gap quadrangle, there are a few outcrops and reported occurrences of gypsum, but it is not everywhere pure, and at no place 

does its reported or observed thickness exceed 3 feet.

CELESTITE

Celestite in a single layer or in lenses only a few inches thick is 

found here and there in the De Queen limestone member of the 

Trinity formation, but it is of no commercial importance. The 

largest outcrops are at a locality 1 mile northwest of Martha post 

office and at another locality a quarter of a mile north of Martha, 

in the De Queen quadrangle.

PHOSPHATE

Widely separated layers, lenses, and nodules of black phospate 

rock, which reach in places a thickness of V/2 inches, are found in 

shale in the basal part of the Stanley shale, both above and below 

the Hatton tuff lentil, in the vicinity of the Cross Mountains west 

of Wickes and Grannis. A few small phosphatic nodules were seen 

near Gillham, but these are probably near the middle of the Stanley. 

This rock is black, has a rather high specific gravity, and a fracture 

that varies from platy and uneven to conchoidal, and weathers to 

a white or yellow color on exposed surfaces. Chemical analyses of 

two samples show that they contain 6.08 and 10.56 per cent of phosphorus pentoxide, equivalent to 13.28 and 23.07 per cent of tricalcium 

phosphate, respectively. It is at once obvious that this rock does 

not contain a high enough percentage of phosphate and does not 

occur in sufficient quantity to be of commercial importance.

PYRITE AND MARCASITE

On the left bank of Caddo River at the west edge of the village 

of Caddo Gap is a prospect revealing a deposit of pyrite and marcasite. The first work at this locality, it is reported, was done about 

1830, and the next in 1915 and 1916. The openings consist of a 

shallow pit and three shafts, of which the deepest is 40 feet deep. 

A drift was run 30 feet to the west from the bottom of the 40-foot 

shaft, and another drift 12 feet long was made in this shaft at a 

depth of 23 feet. In addition three drill holes have been sunk; one 

of these is 75 feet deep, another 78 feet, and the third 100 feet. At 

the time of the visit (1916) the pit and shafts were filled with water, 

which was standing at the same level as the water in the river. The 

rocks penetrated by the openings are very pervious, and water from 

the river seeped through them so rapidly that the prospectors at 

times could not keep it out of the openings with a 4-inch pump.
176 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

The openings penetrated black shale and black earth in the upper 

part of the Womble shale. The minerals on the dump, which 

amounted to 1 or 2 tons at the time of the visit, consisted mostly 

of marcasite but partly of pyrite. The character of the minerals 

thus observed indicates that they occur as irregular masses or veins 

with rounded and stalactitic forms in the shale, free from quartz or 

other gangue minerals, though the sulphides at places inclose fragments of shale which they have cemented together. One mass of 

ore that was found in the drift is said to have weighed a ton. The 

masses of ore and partings between them are said to dip 82° N., and 

nearly all the masses are said to have been found within a zone having this dip that is 6 feet wide and strikes N. 65° E. Analyses 

are said to show that the sulphides contain 51.54 per cent of sulphur, 

0.004 per cent of arsenic, and 0.03 per cent of zinc.

The deposit of pyrite and marcasite at this locality has not been 

proved to be of minable size. Furthermore, if mining or additional 

prospecting is done, the pumping of the water that would seep from 

the river into the workings would be very expensive.

COPPER, GOLD, AND SILVER

Copper minerals are associated with the lead and zinc ores above 

described. These minerals, including chalcopyrite and native copper, 

have been prospected for very extensively in the mountains in the 

northern parts of the De Queen and Caddo Gap quadrangles, but 

they have not been found in commercial quantity at any place.

Gold and silver have also been prospected for at many places in 

the mountainous parts of the quadrangles, but no deposits of value 

have been found. Small deposits of silver-bearing galena have been

prospected from time to time near Silver City, a few miles north 

of the northeast corner of the Caddo Gap quadrangle, but very little 

or no lead or silver has been sold from them.

CLAY

The largest clay deposits are the thick beds of variegated clay of 

the Trinity formation in the southern parts of the quadrangles, but 

yellow and red surface clays are found at many places in other 

parts. All these clays, if properly worked, are suitable for the 

manufacture of common building bricks and drain tile. Common 

building bricks have been made at Murfreesboro, Nathan, and De 

Queen. In the districts where building stone is not plentiful a 

small quantity of leached clay from " crawfish " lands is mixed with 

straw and used to construct chimneys whose framework consists of 

short timbers laid one upon another or nailed to upright pieces 

at the corners.
ECONOMIC GEOLOGY 177

Beds of light-colored clay occur at many places in the Tokio formation from the vicinity of Tokio eastward beyond the east line 

of the Caddo Gap quadrangle. These clays include plastic ball 

clay and nonplastic kaolin, some of which is practically free from 

sand and from iron stains. The thickest beds are 6 feet thick. A 

5-foot bed of nonplastic light-colored kaolin possessing the properties of fuller's earth occurs in the N. i/2 SE. % sec. 24, T. 8 S., K. 25 W. 

This kaolin, as well as others, is apparently altered volcanic ash 

and would be suitable for the manufacture of pottery and probably 

for enameled fire bricks and chinaware. The kaolin at this locality 

is present in large quantity in two hills, in one of which the overburden of sand and gravel is 15 feet thick at the crest of the hill 

and in the other the overburden, of the same character, is 24 feet 

thick at the crest. Many of the clay deposits in this part of the

Caddo Gap quadrangle have been prospected by means of pits, but 

thus far no mining has been done. Some of the deposits have been 

described by J. C. Branner in Bulletin 351 of the United States 

Geological Survey, and they have all been described by C. S. Koss, 

H. D. Miser, and L. W. Stephenson in Professional Paper 154.

Beds of coal-black soft earth, which is known locally as graphite 

and " mineral black," occur near the top of the Womble shale in the 

Caddo Gap quadrangle. This material has probably been derived 

by weathering from beds of black sandy shale. A bed of such earth, 

32 feet or more thick, has been prospected by meWis of a tunnel and 

an open cut 2 miles above the mouth of Gap Branch, near Caddo 

Gap. An analysis is said to show that it contains 10 per cent of 

carbon. Similar earth from other localities in western Arkansas has 

been tested to determine the presence of graphite. The carbon 

which gives the earth its black color was found not to be in the form 

of graphite.

SHALE

The Mazarn, Womble, and Stanley shales afford an inexhaustible 

quantity of shale suitable for the manufacture of red building bricks. 

In order to give these shales the proper plasticity for this use it might 

be necessary to mix with them some of the surface clay. Thus far 

none of the shale deposits have been developed.

LIME

The only limestones that crop out in these quadrangles are those 

of the Collier, Mazarn, Womble, and Trinity formations. Those in 

the Womble and Trinity have been quarried in a small way at several places for making lime. They have no valueoexcept for local 

use.
178 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

BUILDING STONE

Sandstone suitable for rough masonry occurs in large quantities 

in the Crystal Mountain, Blakely, Blaylock, Stanley, Jackfork, and 

Atoka formations, but thus far no quarries have been opened. The 

massiveness of most of this sandstone is its principal drawback for 

most purposes. The many joints would facilitate quarrying. Limestone in the Trinity and Womble formations, gravel conglomerate 

in the Trinity and Woodbine formations, peridotite near the mouth 

of Prairie Creek, and red slate from the Missouri Mountain slate 

have been used in small quantities for rough masonry. They are 

nowhere suitable for superstructural work. Boulders from the 

mountain slopes and cobbles from the terrace and alluvial deposits 

and the base of the Pike gravel are suitable for rubble work. Some 

of these stones have been so used at Murfreesboro. Variegated novaculite in such masonry presents a pleasing appearance. Some of it 

was used in the construction of parts of the Missouri Pacific Kailroad 

station at Hot Springs, Ark., which was destroyed by fire several 

years ago. The results of physical tests made by the Bureau of 

Standards on a sample of dense chalcedonic novaculite from Caddo 

Gap were as follows:

Compression tests, specimens dry, average of three tests, 44,137 

pounds to the square inch. Absorption tests, percentage of absorption by weight, average of three tests, 0.129. Apparent specific gravity, average of three tests, 2.614. Weight of dry stone, 163.4 pounds 

to the cubic foot.

SAND

Sand suitable for plaster and cement is abundant in the Trinity

and Tokio formations in the southern parts of the quadrangles; 

in other parts it may be obtained along the streams where it has 

collected during high stages of the water.

NOVACULITE FOB POTTERY AND GLASS

The basal part of the Arkansas novaculite is composed almost 

wholly of silica, and it is sufficiently white and free from impurities 

to be quarried and pulverized for use in making pottery. The hardness of the novaculite precludes its use for the manufacture of plate 

or ordinary glass, because the work of crushing it would be very 

expensive. On the other hand, the purest grades might be suitable 

for optical glass.

OILSTONES

At Hot Spririgs, Ark., about 25 miles east of the Caddo Gap 

quadrangle, the Arkansas novaculite yields two varieties of oilstones the " Ouachita " (sometimes spelled Washita), which is a
ECONOMIC GEOLOGY 179

rather porous stone of fine quality for sharpening carpenters' tools, 

and the "Arkansas," which is a dense stone suitable for sharpening 

the smallest pointed tools or giving a very fine edge to surgical 

instruments. Kock of these two varieties probably occurs in commercial quantities in the Caddo Gap and De Queen quadrangles, but 

no quarries have been opened. For further information on this 

subject the reader is referred to the Hot Springs folio (No. 215) of 

the Geologic Atlas of the United States, and to volume 3 of the 

Annual Report of the Arkansas Geological Survey for 1890.

PEBBLES FOB TUBE MILLS

The novaculite pebbles in the Trinity, Tokio, and Woodbine formations and in the terrace and alluvial deposits in these quadrangles 

have never been used in tube mills. They are, however, of such a 

character that the authors believe well-selected pebbles may be suitable for this purpose. The only way to determine their adaptability 

to this use is by actually using some of them in tube mills. If the 

pebbles are found to be suitable, the farmers living in the region 

could be employed at idle times to collect, grade, and size them. The 

industry would thus not require the investment of a great amount of 

capital.

The pebbles range from a small fraction of an inch to 10 inches 

in diameiter, bu^ the smallest ones predominate. The tube-mill 

pebbles in greatest demand are from 2 to 4 inches in diameter, though 

some as small as 1 inch and some as large as 7 inches are used. The 

2 to 4 inch pebbles are most abundant in the basal part of the Pike 

gravel from Ultima Thule eastward, in the gravels of the Woodbine and Tokio formations, and in the terrace deposits and gravel bars 

along Muddy Fork, Little Missouri River, and other streams farther 

east. The gravel bars are largest along the; two streams just named, 

some of them occupying several acres, and the gravel in them is in 

places roughly assorted according to size.

Most of the novaculite pebbles are of dense gritty fine-grained 

homogeneous novaculite that is translucent on thin edges. They 

break very much like flint or chert, with an uneven to conchoidal 

fracture, and usually have a waxy luster likei chalcedony. Most of 

the pebbles are white with a bluish tint, but many of them show 

different shades of red, gray, green, yellow, and brown, and some 

are black. In some parts of the area all the pebbles are bleached 

white, but upon being fractured they show their original color.

In shape the pebbles vary from slightly rounded to well rounded. 

None of them are spherical, and very few are nearly so. Although 

the slightly rouinded pebbles predominate, their edges are well 

rounded. Part of the rounding took place in the streams1 that car-
180

ri<ed the pebbles from the Ouachita Mountains, but most of it probably took place on the beaches of the Cretaceous sea. A few pebbles 

have smooth faces that are parts of joint planes of the beds from 

which they came. Most pebbles have such planes and other cracks 

within them, but many are free of these flaws. The pebbles, as a rule, 

have smooth surfaces; but some have1 pits, owing to the presence of 

cavities in the parent rock, and some have rough surfaces from 

impact with one another. A few are highly polished. A small proportion of the pebbles consist of porous novaculite that would wear 

down faster than the denser rock. Some of the pebbles have parallel 

laminae, and such pebbles usually have planes of weakness. The 

novaculite pebbles are almost pure silica, as is shown by the accompanying average of several analyses of the Arkansas novaculite,8 

and they are so resistant to weathering that they are usually as 

firesh as the unweathered novaculite found along its outcrops in the 

Omachita Mountains.

Average analysis of Arkansas novaculite

Silica (Si02 )_________________________________ 99.50

Alumina (A12O3 )_____ .20

Ferric oxide (FfeOa)_____ . 10

Magnesia (MgO) - .05

Lime (CaO)___________ __ ___ .10

Soda (Na2 0)___________.._______________ .15

Potash (K2 0)____ ________________________ .10

Loss on ignition (water)___ __ ___ __ - .10

100.30

The specific gravity of dense chalcedonic novaculite from Caddo

Gap has been determined by the Bureau of Standards to be 2.614.

A determination, by C. E. Wait, of the specific gravity of what is 

called in the trade the "Arkansas stone," a variety of novaculite 

nised for abrasives, gave 2.649.4 A determination of the specific 

gravity of the same kind of stone at the standard temperature, made 

by the Arkansas Geological Survey, gave 2.64S.4 The specific gravity 

is less than that of quartz in crystals, which varies from 2.653 to 

2.660, but it falls within the limits for pure cryptocrystalline forms 

such as flint or chert, which may have a specific gravity as low as 2.60. 

The percentage of absorption by weight of the dense novaculite 

from Caddo Gap was determined by the Bureau of Standards to 

be 0.127. Similar tests of the " Arkansas stone " from two quarries 

near Hot Springs were made by the Arkansas Geological Survey; 

the percentages of absorption found were 0.06 and 0.07. 5

"Griswold, L. S., Whetstones and the Novaculites of Arkansas: Arkansas Geol. Survey 

Ann. Rept. for 1890, vol. 3, p. 90, 1892. 

4 Idem, p. 93. 

'Idem, pp. 93-94.
ECONOMIC GEOLOGY 181

The hardness of the novaculite is the same as that of quartz, but 

as shown by the slight protrusion of quartz veins, due to differential 

abrasion, on surfaces of many of the pebbles containing such veins 

the novaculite is somewhat less resistant to abrasion than vein quartz. 

Novaculite is comparatively brittle, being easily broken by a hammer. 

Its brittleness may, in fact, bar its economic use in tube mills.

The crushing strength, as determined by taking the average of 

three compression tests made by the Bureau of Standards on novaculite from Caddo Gap, is 44,137 pounds to the square inch.

The gravel in the Tokio formation is usually mixed with less red 

Clay than those in the Trinity and Woodbine formations. The stream 

gravel is also in most places free of clay.

ROAD MATERIAL

The Caddo Gap and De Queen quadrangles are abundantly supplied with road material. The Bigrfork chert, Arkansas novaculite, 

Trinity formation, Woodbine formation, Tokio formation, and terrace and alluvial gravels afford very large supplies for laying both 

foundations and surfaces.

A characteristic of the Bigfork chert which especially facilitates 

its use on roads is its minutely shattered or fractured condition. It is 

easily accessible and can be loosened at its outcrops in the sides of 

the hills by blasting and then dug out with picks and put on the 

road with little or no preparation. It also occurs in large quantities 

as finely broken talus at the bases of the hills. The comparative 

brittleness of this chert allows it to pulverize and become firmly 

compacted into a smooth, firm mass, though not hardened, ifor no 

calcareous material is mixed with it to act as a bond. Nevertheless, 

owing to the presence of more or less clayey material, it makes a 

firm, smooth road surface. " It forms a natural macadam on many of 

the roads within its area of outcrop and is used to some extent in 

the construction of public roads.

The Arkansas novaculite is not so much fractured as the Bigfork

chert, and the blasting of the massive beds in which it occurs and

the crushing of the rock would be more expensive than the preparai tion of the Bigfork. On a few talus slopes large and small stones of

novaculite have collected in considerable quantities.

The many beds and lenses of gravel, especially the basal ones, in 

the Tokio, Woodbine, and Trinity formations are widely distributed 

in the southern parts of the quadrangles. In fact they and their 

residual materials form the predominating surficial deposits found' 

in those parts of the quadrangles that are underlain by Cretaceous. 

' sediments. They consist of novaculite and other hard pebbles intermixed or interbedded with clay and sand, and although the beds6242 29 13
182 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

range in thickness from a few inches to 100 feet some of them maintain a thickness of between 25 and 50 feet over considerable areas. 

Enough sand and clay is usually mixed with the pebbles to make a 

firm, compact road. The gravel thus constitutes an accessible and 

enormous supply of good road material. Like the Bigfork chert 

it forms a natural macadam in those areas where it occurs on the 

surface.

Gravel of much the same character as that just mentioned constitutes a large proportion of the deposits along the large and small 

streams of the quadrangles. The larger areas of stream deposits are 

represented on Plate 3 and are there designated " alluvium " and 

" terrace deposits." Most of these areas are covered with a deposit 

of sand and loam a few feet thick. Where the gravel is thus covered 

the best places for obtaining road material are along slopes where 

the gravel crops out and from the gravel bars usually found along 

the streams. These bars are largest along Muddy Fork and Little 

Missouri and Caddo Eivers.

At the village of Cove, in the De Queen quadrangle, a large 

quantity of hard dark-bluish sandstone in the Stanley shale has 

been quarried and crushed for ballasting the Kansas City Southern 

Railway.

The cobbles and Jarge pebbles commonly found more abundantly 

at the base of the Pike gravel than elsewhere are suitable for riprap 

and curbing. Great quantities of them occur in places along the 

streams.

WATER RESOURCES

The areas herein described are well watered, the mean annual precipitation being 53.27 inches at Center Point, in the Caddo Gap 

quadrangle; 54.21 inches at Amity, which is 2 miles east of the 

quadrangle; and 50.6 inches at Mena, wnich is 5 miles north of the 

De Queen quadrangle. A considerable portion of the water immediately flows off the surface into the streams, which are described 

in the section entitled " Drainage," and another portion sinks into 

the ground and into open spaces in the rocks, and after a longer or 

shorter period of time and by a more or less circuitous route much 

of it reaches the surface again as springs.

All the rock formations, including even the shales, contain water, 

which issues as springs or which may be reached by means of wells. 

The formations which contain the least water are the Missouri Mountain slate, the Polk Creek shale, and the Brownstown marl, and those 

which contain the largest quantities are the Crystal Mountain sandstone, the Bigfork chert, the Arkansas novaculite, the Trinity formation, and the Woodbine formation. Of these'the Bigfork chert 

contains the most water because of its uniformly shattered condition.
ECONOMIC GEOLOGY 1$3

its considerable thickness, and its comparatively large area of outcrop. Many springs flow from it or find outlet to the surface through 

other formations. In fact, most of the fine springs in the Ouachita 

Mountains between Hot Springs and the western border of the State 

and some in Oklahoma come from this chert.

Wells. Wherever spring water is not available, shallow wells that 

will yield a supply of water sufficient for at least household purposes, 

if not for stock, can be dug or drilled at most places, even on the 

uplands. Such a supply can usually be procured without exceeding 

40 feet in depth. According to local conditions, water may be obtained at greater depths in some places in the Athens Plateau and 

farther north, but flowing wells there can not be expected because 

of the close folding and high inclination of the rocks.

A number of artesian wells, some of which are flowing wells, have 

been drilled in the Coastal Plain in the southern parts of the quadrangles. The water from all the wells except one at Delight is 

obtained from the Pike gravel member of the Trinity formation and 

from beds of sand that appear to be a short distance above this gravel. 

The well at Delight, which is a flowing well 112 feet deep, receives its 

water from a bed of sand near the base of the Tokio formation. 

Figures 8 and 9, maps of the southern parts of the De Queen and 

Caddo Gap quadrangles, show, by contours the maximum depth to 

which wells should be drilled for artesian water in the Trinity, Tokio, 

and Woodbine formations and the areas within which flowing wells 

may be expected. Broken contours are based on incomplete data. 

The .boundaries of the areas within which flowing wells may be 

expected are approximate, for they are based on incomplete data.

The contours in Figures 8 and 9 show the position of the bas'e of 

the Trinity referred to sea level. Artesian water at most places 

occurs near the base of the Trinity, but water for a flowing well at 

Delight comes from the Tokio formation. No water should be 

expected in Paleozoic rocks underlying the Trinity.

Several wells ranging in depth from 80 to 258 feet have been 

drilled at and near Murfreesboro. Some of them are flowing wells, 

and in others water rises within a few feet of the surface. A number 

that formerly flowed ceased to flow when new wells were put down 

near by.

Two wells about 170 feet deep were drilled at the east end of the village of Kimberley by the Kimberlite Diamond Mining & Washing 

Co. They passed through 18 feet of gravel (Quaternary), then 60 feet 

of clay and thin sandstone (Trinity), then 85 to 90 feet of variegated 

clay (Trinity), and next 4 to 5 feet of pebbly sand (Trinity) containing some pyrite and some black sand (magnetite). Some water 

was found just above the variegated clay, and a large quantity was
R.27 E. R.33W. R. 32 W. R. 31 W. R30 

V%t%0( Area within which flowing 

E%%%3 wells may be. expected

FIGURE 8. Map of the southern part of the De Queen quadrangle, showing by contours the m

water in the Trinity formation and also the areas within which flowing wells may be expe

referred to sea level. Broken contours are based on incomplete data
R. 28 W. R. 27 W. R. 26 W. 

fc%%§3 Area within which flowing 

B%%a wells may be expectecT

FIQORB 9. Map of the.southern part of the Caddo Gap quadrangle, showing by contours the ma

water in the Trinity, Woodbine, and Tokio formations and also the areas within which flowing! 

the Trinity formation referred to sea level. Broken contours are based on incomplete data
186 DB QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

found in the bed of pebbly sand at the bottom of the wells. The 

wells flowed when they were completed, but they ceased to flow after 

Walter Mauney drilled a well a short distance to the north. The 

Mauney well was drilled at a lower altitude than the other two and 

to about the same depth. It penetrated the same water-bearing bed 

as the other two wells and reduced the pressure of water in that bed. 

At the time of examination (1916) the Mauney well did not flow 

except by means of a siphon whose lower end was near Prairie Creek. 

Water from the two wells of the Kimberlite Diamond Mining & 

Washing Co. was used in the diamond-washing plant of the company, 

which was operated from 1913 to 1919.

Three artesian wells have been drilled in the northern part of the 

city of De Queen to supply water for ,the roundhouse of the Kansas 

City Southern Railway Co. No. 1 well, 289 feet deep, is 50 feet 

north of the office at ,the roundhouse; No. 2, 253 feet deep, is 200 feet 

north of No. 1; and No. 3, 200 feet deep, is 200 feet north of No. 2. 

The water from all three wells is said to come from a very fine white 

sand. The wells do not flow, but the water rises to a point near the 

surface.

Three other artesian wells in De Queen supply water for the city 

and for the ice plant. Two of the wells are a short distance east of 

the railroad station and the other is at the ice plant farther south. 

The wells have an average depth of about 250 fee.t, and two of them 

originally flowed. The quantity of water that they are capable of 

producing is said to be about 2,000,000 gallons a month.

Two flowing wells, each 275 feet deep, are 1 mile south of De 

Queen, near the pumping station of the Prairie Pipe Line Co., which 

drilled the wells ,to obtain water for the pumping station.

A flowing well, 350 to 360 feet deep, is said to have been drilled 

in the valley of Rolling Fork in the W. y2 sec. 21, T. 8 S., R, 32 W. 

4 miles west-northwest of De Queen.

Gold springs. Cold springs are numerous in all parts of the 

quadrangles, but are most numerous and largest in the mountainous 

districts. Many of the springs yield water of great purity, but the 

water of others contains large quantities of mineral salts. On 

account of this great difference in the character of their waters and 

on account of the very large number of springs it is no.t advisable to 

enumerate and describe the springs without a special study, which 

has not "been made. A few of the springs are shown on Plate 3.

Hot springs. Hot or warm springs are known at four localities 

in the Caddo Gap quadrangle. One of these is in the gap .through 

Caddo Mountain known as Caddo Gap; another is reported to be 

2 miles southwest of the gap; the .third is at the east end of Redland
ECONOMIC GEOLOGY 187

Mountain, 11 miles west of Greenwood; and the fourth is on Little 

Missouri River, 6y2 miles southeast of Big Fork post office.

The hot springs at Caddo Gap were discovered in February, 1908, 

by J. M. Davis, of that place. The hot water has its outlet in 

the bed of Caddo River, in the gap where this stream cuts through 

Caddo Mountain, and this peculiar location prevented the springs 

from being discovered earlier. The water rises between the vertical 

beds of the uppermost division of the Arkansas novaculite. Cement 

inclosures have been constructed around two points of issue, 22 feet 

apart, on the west side of the river, and the springs issuing through 

these inclosures ar-j here called North Spring and South Spring. 

Much hot water still issues from the bed of the river. The surface 

of the North Spring stands about 15 inches and that of the South

Spring about 10 inches above the river at average stage.

The temperatures of the springs were determined on July 2, 1910, 

by Mr. Purdue, who found the North Spring to have a temperature 

of 95° F. and the South Spring 96.5° F. Mr. Miser determined the 

temperatures at 6 p. m. May 8, 1916, at the places where the hot 

waters enter the concrete basins, and found them to be 94° F. for the 

North Spring and 96.8° F. for the South Spring. The flow of each 

spring was calculated from a rough determination to be 5 gallons a 

minute. A few bubbles of gas, which may be carbon dioxide, rise 

to the surface of the water. Analyses of the waters are shown below.

Analyses of water from hot springs at Caddo Gap, in parts per million 

[Computed from analyses by W. M. Bruce]

SilicA(SiOi)..... .....................................................................

Magnesium (Mg) _ . _ . ___ .... . ____ . _ ... __ .. _________ ..

Sodium (Nn).... ................... _ .............................. __ ... _ ......

Potassium (K) _______ ............. ________________________ ..

Carbonic acid radicle (COa).... _ . __ .. __ . __ - _______________ ...

Chlorine (Cl)... __ .................................................. ..............

South 

Spring

15. 600

7.000

 38. 876

2.166

7.526

.000

68. 265

1.419

4.848

145. 700 

20. 000

North 

Spring

IS. 700

. 7.200

41. 680

4.235

3.349

.000

67. 085

2.313

7.138

151.700 

16.000

A hot spring is reported by Mr. W. B. Barton as occurring near 

the quarter corner on the line between sees. 23 and 26, T. 4 S., R 

25 W., 2 miles southwest of the hot springs at Caddo Gap. The 

analysis given below has been furnished by Mr. Barton, who says 

that the sample of hot water contained some cold surface water that 

was entering the spring.
188 Da QUEEN" AND CADDO GAP QUADRANGLES, ARKANSAS

Analysis of water from hot spring 2 miles southwest of Caddo Gap, in parts

per million

[W. F. Manglesdorf, analyst]

Silicia (SiO.)____________________________ 15.4

Iron (Fe)_______________________________ 1.2

Aluminum (Al)___________________________ .7

Calcium (Ca)____________________________ 39.8

Magnesium (Mg)___________________;____ 2.3

Potassium (K)___________________________ 1.3

Lithium (Li)____________________________ .6

Sodium (Na)____________________________ 9.1

Carbonic acid radicle (CO8 ) ___________________ 69.0

Sulphuric acid radicle (SO,.)___________________ 8.3

Chlorine (Cl)__________________________ 8.0

155.7

A warm spring whose temperature was determined by Mr. Miser 

on August 7, 1916, to be 77° F., is on the east end of Bedland Mountain and about 100 feet above Self Creek. The water issues from a 

crevice between two massive, steeply dipping layers of novaculite in 

the uppermost division of the Arkansas novaculite. The flow is 

sufficient to fill a 1-inch pipe leading from the spring. The water 

contains in solution much iron, which is deposited as a brown coating 

in the wooden troughs carrying the water down the mountain side 

and on the rocks over which the water flows.

A warm spring -whose temperature was determined by Mr. Miser 

on August 1,1916, to be 74° F. is on the left bank of Little Missouri 

River in the northern part of sec. 17, T. 4 S., B. 27 W. The water 

issues at a number of places within an area several feet across about 

15 feet from the river bank. The aggregate flow would be sufficient

to fill a 3 or 4 inch pipe leading from the spring.

The source of the hot waters of the above-described springs is not 

known. They may be meteoric waters that have been heated in some 

way deep below the surface, or they may be hot waters that are given 

off by cooling igneous rocks far below the surface. If the waters are 

meteoric the source of their heat may be due to chemical reactions 

within the rocks through which the water flows, accumulated heat 

from friction, the presence of hot igneous rocks beneath the surface, 

or the breaking down or other action of radium along the underground course of the water. This question, which has been raised 

also concerning the hot springs at Hot Springs, Ark., east of the 

areas under discussion, can not be definitely answered with the 

information that is now available, but the writers believe that the 

waters are meteoric.

Water power. All the streams of the quadrangles are small, the 

largest ones being merely creeks which are easily forded at low
ECONOMIC GEOLOGY* 189

stage. At a number of places water power has been utilized to run 

small grist and lumber mills and cotton gins, but this use has been 

largely replaced by steam and gasoline engines. Many places in the 

quadrangles, especially the water gaps where short rapids or lo\\; 

falls exist, afford favorable sites for small power plants. Among 

the most promising sites are Caddo Gap, through which Caddo 

River flows, the falls of Cossatot Eiver in sec. 17, T. 5 S., R. 30 W., 

and the falls of the Little Missouri just north of the MontgomeryPike County line.

SOILS

Except the wide belts of'alluvium and patches of terrace deposits 

along the streams in the Coastal Plain and the small tracts of alluvium in the Ouachita region, the soils of the Caddo Gap and De 

Queen quadrangles are residual, having been derived from the disintegration of the different rock formations represented in the areas. 

The soils thus differ in character from place to place.

The Collier shale, Crystal Mountain sandstone, Blakely sandstone, 

Bigfork chert, Polk Creek shale, Blaylock sandstone, Missouri Mountain slate, and Arkansas novaculite have a prevailingly rocky thin 

soil, derived from either their own outcrops or adjacent beds. The 

slopes and crests of the ridges where they form the surface rock are, 

as a rule, not fit for agriculture but are best adapted for the growth 

of timber, with which they are densely covered in most places. Although such areas are forested, they grow wild grasses well and are 

thus suitable for grazing.

The soil overlying the Mazarn and Womble shales is not everywhere of the same character. Along Caddo River and other streams 

it consists in great measure of transported materials which occupy 

narrow stream flats or the lower parts of slopes, and although it is 

more or less stony it is fertile, whereas in the higher parts most of the 

soil is shallow, clayey, stony, and poor. The better land is well 

suited for general farming, the poorer for grazing and fruit culture.

The soils of the Stanley shale are prevailingly sandy though somewhat clayey in the higher areas, but in the valleys they are less sandy 

and more clayey. They are porous, thin, and brown, yellow, and 

gray, and in some places they are underlain by soft, altered sandstone, in others by red clay. Much of the tillable soil is stony, containing pieces of quartz and sandstone, and in many places, especially 

adjacent to the larger streams, boulders and rock ledges abound, 

making such land practically worthless except for grazing and for 

timber. The largest tracts of tillable land stretch along the divides 

between the streams and include the fairly even upland country along 

the Kansas City Southern Railway and around Galena, Burg, Um-
190 DE QUEEN AND CADDO GAP QUADRANGLES, ARKANSAS

pire, and Mineola, in the De Queen quadrangle, and around Athens, 

Henry, Newhope, Daisy, Kirby, and Glenwood, in the Caddo Gap 

quadrangle. The soils in these parts of the quadrangles are adapted 

^o general farming and fruit culture. They show considerable fertility after the timber is cleared away^ but unless they are properly 

tilled and fertilized this richness lasts but a few years.

The Jackfork sandstone produces a very poor sandy soil and there 

are few farms on it. Those parts that have been cleared have been 

generally abandoned. The land is best suited for grazing and for the 

growth of pine timber, which prevails in the belts where this sandstone is exposed.

The Atoka formation in the more level tracts found here and there 

yields a soil of fair fertility.

The gravel of the Trinity formation, the pebbles of which are 

embedded in clay and sand, produces a valuable soil for general 

farming and especially for the cultivation of fruit. Its distribution is discussed under the description of this formation. Most of the 

area where the Trinity crops out is occupied by a poor sandy yellow 

or gray soil, but some of the "black lands" formed by the Dierks 

limestone lentil and the De Queen limestone member are more fertile. All these soils under proper care and fertilization are suitable 

for general farming.

The soil of the Woodbine and Tokio formations is gravelly almost 

everywhere in the quadrangles herein described. The pebbles, like 

those in the Trinity formation, are mixed with clay and sand. This 

soil is thus similar to that of the basal gravel of the Trinity just 

described. It is especially adapted for fruit culture.

The Brownstown formation yields a fertile soil that is black and 

waxy where not mixed with surficial deposits, but the subsoil is 

yellow.

The alluvial soils are usually dark, sandy loam and afford the 

best farming lands in the quadrangles.

TIMBER

The virgin forest which once covered all parts of the quadrangles 

has been largely destroyed through the cutting of the commercial 

timber. Most of the cut-over tracts have not been put under cultivation but have been permitted to reforest themselves, the result being 

that the greater part of the quadrangles is still timbered. Lumbering has thus been and is still an important industry and owing to 

the roughness of much of the country will remain so, although it is 

being rapidly succeeded by agriculture in those parts where the land 

is tillable. A considerable portion of the wooded areas in the northeast corner of the De Queen quadrangle and in the northern part
ECONOMIC GEOLOGY 191

of the Caddo Gap quadrangle is comprised in the Ouachita National 

Forest.

A short-leaved variety of yellow pine is probably the most common 

species, being found in all parts of the quadrangles. Magnificent 

forests, containing little else than this pine, are found in the belts 

where the Jackfork sandstone is the surface rock, in much of the 

area occupied by the Stanley shale, and in some of the gravelcovered areas of the Trinity and Tokio formations. Oaks, including 

white oak, red oak, post oak, and other varieties, are common, and 

the white oak is the most abundant of these. Other kinds of trees 

that grow to a large size are ash, wild cherry, walnut, hickory, 

sycamore, elm, cypress, holly, sweet gum, black gum, beech, red cedar, 

and maple. The cypress and holly trees are most numerous in the 

southern parts of the quadrangles, and red cedars are most plentiful

along Cossatot River and Rolling Fork.

The timber on the higher ridges of the mountainous districts has 

a peculiar distribution; pines grow with the hardwoods on the south 

slopes nearly to the crests, and scrub oaks and small hickories occupy 

the crests, whereas on the north slopes the hardwoods grow larger 

than on the south slopes and few pines are seen.

INDEX

A Page

Abstract of the report.. _ ________ ix-xi 

Alluvium, features of'.____________ 99 

American mine, map showing distribution

of peridotite at____.____ 108 

American peridotite area, description of... 111-112 

Anticlines of the Ouachita Mountain region.. 11-12 

Antimony, deposits of____-_____ 150-153 

Arkansas mine, diamond plant at, plate

showing......................... 148

Arkansas novaculite, age and stratigraphic

relations of.... .. 57-59 

average analysis of_ _ 180 

deposition of........................... 131-132

distribution of ________. ______ 49-50 

lower division of, at Caddo Gap, plate

showing._____________ 28 

nature and definition of......___.. 49,50-55

origin of................................. 55-57

suitability of, for pottery and glass_.... 178

tests of.._______________... 178

Arkansas Valley, geography and geology of.. 12-13

Asphalt, deposits of....__________ 157-161 

production of.______________ 161 

source of...___________.___ 161-162

Athens Plateau, description of.'..._____ 7-8,17 

folding in.............................. 123-124

Atoka formation, deposition of__..___ 134-135 

description of..__ ... 77-79

B

Bellah mine, description of...... __ 166-167

Berry, E. W., quoted........................ 92

Bibliography__ . 1-2 

Bigfork chert, deposition of.._ 129

description of.................- ... 36-39

"Black ground," nature of...... . 101-102

Black Lick peridotite area, description of.. 112-113

map showing distribution of peridotite in. 108 

Blakely sandstone, deposition of..... 128-129

description of_........... .... 29-31

Blaylock sandstone, deposition of.... 130-131

description of..__... ----- 42-45

"Blue ground," nature of.............. 101,105-106

Brackett, R. N., analyses by.......... .. 172

Brownstown marl, deposition of . .. 142

description of.......---...-... ..-- 94-95

Brucc, W. M., analyses by.................. 187

Building stone, deposits of...__...... 178

Caddo Basin, features of ............. 16-17

Caddo Mountains, features of.......... 15-16

Caddo River, features of.. . -. 19 

Cambrian period, deposition in.............. 127

Caney shale, age of...______............ 72-75

presence of..... __ __..____ 72

Carboniferous period, deposition in.__.. 132-135 

Celestite, occurrence of... ..______.. 175 

Cervantite, analysis of..............____ 152

Chauvenet, Regis, & Bro., analyses by_... 172 

Clay, deposits of.---...................... 176-177

Collier shale, deposition of._...._....... 127

description of............................ 23-24

Copper, occurrence of....................... 176

Cossatot anticline, description of.......... 121-122

Cossatot Mountains, features of...._...... 16

Cossatot River, features of....._..___.. 19

Cove Basin, features of...___...._.._ 17

folding in................................ 124

Cretaceous period, deposition in__...... 139-143

drainage during...... ............ 143-144

Cretaceous rocks, generalized section of, plate

showing____..._______ 28 

Cross Mountains, features of....._____.. 16

Cross Mountains anticline, description of_ 123 

Crystal Mountain anticline, description of. 119,121 

Crystal Mountain sandstone, deposition of. 127-128

description of..-.-.........._.......... 24-26

Crystal Mountains, features.of............. 15,119

D

Dale, T. N., quoted......................... 47-48

Davis mine, description of-------.--...._ 167-168

Delight, asphalticsand near.__....__ 158-159

De Queen, log of ice-factory well near._.... 84

De Queen limestone member, features of.... 83

Devonian period, deposition in............ 131-132

Diamonds, concentrate minerals associated

with......_._..--...-..........-- 150

description of..-....... 148-149

from the Arkansas mine, plate showing.. 148 

mining of... 149-150

plate showing................ .... 148

occurrence of.... xi, 99,100,103,107,109,147

production of........-.--.---.-..--.-.- 147-148

Dierks limestone, features of................ 82-83

Drainage of the quadrangles... ... . 18-21 

during Cretaceous time. ... ...... 143-144

F"

Faults in the Paleozoic rocks, occurencc of. 124-125 

Field work, record of-. ................... 2-4

Fodderstack Mountain, section at base of... 163

Folding, in the Paleozoic rocks, effects of... 117-124

record of 135-136

"Fork Mountain slate," features of.......... 61

Fossils, occurrence of, in the Arkansas novaculite... ... 58-59

occurrence of, in the Bigfork chert....... 38-39

in the Blaylock sandstone..... 45

193
194 INDEX

Page

Fossils, occurrence of, in the Blakely sandstone... --..--....-------- 30-31

occurrence of, in the Mazarn shale.... . 27-28

in the Polk Creek shale....--..-.- 40-42

in the Womble shale.--.---.--.----. 33-36

Gas, absence of.. -.. -- 161-162

Girty, G. H., fossils determined by ........ 69

on.the age of the Caney, Jackfork, and

Stanley formations ... . 72-74 

Gold, prospecting for.... ... ..... 176

Gravel, various age designations of ... ,. 97-99 

"Green ground," nature of..-..-.--------- 101,105

Gulf Coastal Plain, geography and geology of- 13-14 

Gypsum, deposits of ....__ 174-175

H

"Hardebank," occurrence of -- 102, 111

Hatton tuff lentil, features of--------------- 63-64

plate showing. 68

Hayes, C. W., quoted-------------------- 158

Hess, F. L., Quoted... . 153 

Honess, C. W., fossils determined by..-.-.- 69-72 

Hot Springs district, sedimentation in. 128,131,132 

Hot Springs peneplain, production and erosion of 144-146

Igneous rocks, intrusion of 140-141

Industries in the quadrangles..... ... 22

Iron, deposits of-..-.---.------------------ 173-174

Jackfork sandstone, definition and distribution of...----------_----------- 75-76

deposition of-.------------------------ 133-134

nature and age of- -_...___- 72-75,76-77 

Upper and Lower, of Honess, equivalence of . . . 72

Kimberlite mine, map showing distribution

of peridotite at--.-......__ . 108

Kimberlite peridotite area, description of-. 110-111 

Kunz, G. F., quoted....................... 148

Langley, section northeast of....... ....... 165

Lead, deposits of---------.---------.. 166-170

Lebanon, asphaltic sand near..._ . . 159-161 

Limestone, in Womble shale, plate showing.. 28

occurrence of 177

Lithic tuff in the Woodbine formation,

features of --------..... 88,89,90

Little Missouri River, features of - ___ 18-19 

Llanoris, detrital material from.............. 10

location of.... ......................... 10

Location of the quadrangles............ ... 4-5

M

Manganese, analyses of ores of 172

deposits of.. ---__....._..... 170-173 

Manglesdorf, W. F., analysis by........... 188

Page

Map of the quadrangles, showing topographic

divisions and drainage pattern_ 4

geologic..._____________ In pocket. 

Marcasite, deposit of...________... 175-176" 

Mazarn Basin, features of .__._____ 17 

Mazarn shale, deposition of_______ 128-129

description of.___. ____. _____ 25-28

undesirable for commercial slate__ .. 154 

Mazarn syncline, description of..___... 122-123 

Metamorphism of the Paleozoic rocks, effects

of 125-126

Millar, Austin Q., quoted.-,.., . 148-149 

Mississippian rocks, description of.__..... 59-79

Missouri Mountain slate, deposition of...... 131

description of. _ 45-49,154-156 

Morgan, G. D., quoted_...._______ 69 

Mountain Fork of Little River, features of- 19-20 

Murfreesboro, asphaltic deposits near..___ 159

O

Oil, absence of.___.___._.___ 161-162 

Oilstones, deposits of-____________ 178-179 

Ordovician period, deposition in_._... 128-129 

rocks of..___________-___.__ 25-42 

Ouachita anticline, description of .. 11-12,118-123 

Ouachita Mountain region, climate and vegetation of...____________ 8-9 

drainage of....__-____.__-__ 8

stratigraphy of-. _._......_.... 9-11

structure of- .. ..___... .. 11-12

surface features of.__.____. ... 6-8

Ouachita Mountains, features of____.... 7

Ouachita peneplain, production and erosion

of. 136-139

Paleozoic formations, classifications of, insert

showing......_................ 22

generalized section of, plate showing__ 28 

Paligorskite, occurrence of...._........._ 109

Pebbles for tube mills, nature and distribution of 179-181

Pennsylvanian rocks, description of--- 77-79

Penrose, R. A. F., jr., quoted . 173

Peridotite, ageof... .. . . 114-115

intrusive, photomicrographs of--__.... 104

plate showing. ___________ 100 

relation of, to other igneous rocks. of

Arkansas___.________ 113-114 

Phosphate rock, occurrence of __. ____ 175 

Pike, asphaltic sand near._........._.. 157-158

Pike gravel member, features of.-.-..___ 81

plate showing... -__...__.____ 68

Polk Creek shale, commercial slate scarce in. 154

deposition of.____.__________ 129

description of.._____.___.___... 39-42

Population of the quadrangles_______,. 21

Prairie Creek, peridotite dike near mouth

of... . 109-110 

Prairie Creek peridotite area, diamonds

from... . 99,103,107,109 

geologic map of __. ____. _____ 100 

intrusive peridotite in. 102-103

location and topography of __. __ 99,100 

minerals in. - 103,106-107,108 

rocks associated with peridotite in__ 100-101 

tuff and fine-grained breccia in....._ 107-109
INDEX 195

Page 

Prairie Creek peridotite area, typos of the

peridotite in.--.---.. ----..-.- 101-102

veins in the peridotite of.. ............... 109

volcanic breccia in..................... 105-107

Prosser, C. S., fossils determined by.--...... 68

Publications, prior, list of ----------------- 1-2

Pyrite, deposit of ___ . - ..- 176-176

Q 

Quartz crystals, occurrence and production

of . . .-- -.. 174 

plate showing. ............. Jt............ 148

E 

Raspberry Peak, height of _ ................ 15

Road material, deposits of. _ ....... ... 181-182

Roads and railroads in the quadrangles...... 21-22

Rolling Fork, features of .----.--- ..... 19

Saline River, features of---...- ..... 19

Sand, deposits of... ------.-..- 178

Schuchert, Charles, fossils determined by.... 68

Shale, deposits of ________ ..-.- ....- 177

"ribboned," plate showing... . .-_...-._. 28

Silurian period, deposition in..-..... ... 130-131

Silver, occurrence of. _ ...... _ ............ 176

Slate, deposits and production of. ......... 153-157

Soils, nature of.. --. .-.....-........-. 189-190

South African diamond-bearing rocks, comparison of Arkansas rocks with. 115-117 

Springer, Frank, quoted.. __ ............... 69

Springs, analyses of water from ............ 187, 188

occurrence of ___ - __ - _ ....... 186-188

Standing Rock, on Board Camp Creek, plate

showing. _ .... . ... 20

Stanley shale, age of. _ . _ _. .. _,.. 72-75 

definition and distribution of.... __ ... 59-60

deposition of- ____ .................. 133-134

fossils and correlation of ----------------- 65-75

nature of.. __ . __ . _ -....--. ___ .. 60-64

polished tuff frotn, plate showing. ....... 68

sandstone in, plate showing _ .......... 28

south of Oillham, plate showing.......... 68

stratigraphic relations of------ ........ 64-65

suitability of, for commercial slate __ ... 157 

Stanton, T. W., fossils determined by....... 85-86

Steiger, George, analysis by.... .. ....-,.. 172

Stephcnson, L. W., fossils determined by.. . . 95

Stibnite, analysis of... ...................... 152

Structure of the Cretaceous rocks ___ ....... 126

ft of the Paleozoic rocks _ ........ _ _ . 117-126

Structure sections across the quadrangles

___ . __ ... ____ . _ In pocket. 

through several mountains in the quadrangles.. ___ . ____ . __ ... 120 

Surface features of the quadrangles .... ___ 14-18

Terrace deposits, description of......_....... 96-97

Tertiary period, events of.........--.....-. 144-146

Tertiary (?) gravel, deposits of ............ 95-96

Timber, distribution of.................... 190-191

Tokio formation, age and correlation of__.. 92-94 

definition of............................ 90-91

deposition of...-...---.....-....,-...-.. 142

nature and distribution of....._...._ 91-92

Trinity formation, definition of..._........ 79-80

distribution of -- --.. .-..- . 80-81 

fossils and correlation of......... ____ 85-86

nature of.-___.__.__.__...__ 81-85

sections of, near Labanon.. __... __. 160,161

Tripoli, analysis of..-.._-.....--.._.... 164

deposits of_.____._...____. 162-166 

production of_____....___....... 164

Tuff, blue-gray, photom icrograph of. .... 108

Ulrich, E. O., fossils determined by.....__ 27-28,

30-31, 33-36, 38-39,40-42,45, 58-69

work of, on the "Johns Valley shale" 74

Ultima Thule gravel, features of............. 81-82

Uplift in the area.................... ... 135-136

Veatch, A. C., quoted...................... 94,143

Vitric tuff in the Woodbine formation, features of.......................... 88-90

Volcanic breccia, plates showing_.._. 100,108

W

Wagner, P. A., quoted.................... 115-116

Wait, C. E., analyses by.................... 152

Water gaps, number of.............__..... 20

Water power, sites for.___.....____ 188-189

Water resources, description of... ____ 182-189 

Wells, depth and flow of . . 183,186 

West Gulf Coastal Plain, features of......... 17-18

White, David, fossils determined by...... 66-68,79

Williams, J. F., quoted..... ..... . 114

Womble shale, deposition of....._.___ 128-129

description of___.___......____ 31-36

undesirable for commercial slate..._... 154 

Woodbine formation, age and stratigraphic

relations of..-._.._-___... 90 

deposition of.......................... 141-142

nature and distribution of............... 86-90

"Yellow ground," nature of..........__. 101,105

Z 

Zinc, deposits of.____......_...__. 166-170

O