GEOLOGICAL SURVEY CIRCULAR 160

DESCRIBED SECTIONS AND CORRELATION 

OF PALEOZOIC ROCKS AT 

GILBERT, CARVER, AND 

MARSHALL, ARKANSAS

By John C. Maher and Robert J. Lantz
UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 160

DESCRIBED SECTIONS AND CORRELATION OF PALEOZOIC ROCKS AT 

GILBERT, CARVER, AND MARSHALL, ARKANSAS

By John C. Maher and Robert J. Lantz

Washington, D. C., 1952.

Free on application to the Geological Survey, Washington 25, D. C.
BOONE

R.I9W. R.I8W. R.I7W. 

5 Miles

Figure 1. --Location of Paleozoic sections and Marshall water well, Newton and Searcy Cou
DESCRIBED SECTIONS AND CORRELATION OF PALEOZOIC ROCKS AT 

GILBERT, CARVER, AND MARSHALL, ARKANSAS

CONTENTS

Page 1 '

Introduction ............................

Representative measured sections

of Paleozoic rocks ..................... 3

Everton formation, Gilbert .......... 3

St. Peter sandstone, Gilbert ......... 3

Plattin limestone, Gilbert ........... 3

Fernvale limestone, Gilbert ......... 4

Cason shale, Gilbert ................ 5

Brassfield limestone, Gilbert ........ 5

Lafferty and St. Clair limestone,

Gilbert ......................... 6

Representative measured sections of 

Paleozoic rocks Continued 

Upper part of Boone formation,

Gilbert .........................

Lower part of Boone formation,

Gilbert .........................

Batesville sandstone, Ruddell shale,

and Moorefield formation, Gilbert, 

Carboniferous (Mississippian) and

Ordovician rocks, Carver ... k ..., 

Log of Marshall water well 3, Marshall

Page

ILLUSTRATION 

Figure 1. Location of Paleozoic sections and Marshall water well, Newton and Searcy Counties, Ark.

10

12

Page

INTRODUCTION

In 1949 the U. S. Geological Survey, with the 

cooperation of the Division of Geology, Arkansas 

Resources and Development Commission, began 

stratigraphic investigations in northern Arkansas to 

aid in the search for oil and gas in the Arkansas 

valley. Surface mapping of the Paleozoic rocks on 

the north side of the Boston Mountains in Newton and 

Searcy Counties has been carried on concurrently 

with subsurface studies in the Arkansas valley since 

that time. The lower Paleozoic rocks have been 

mapped in detail, while the upper Paleozoic rocks 

have received only incidental study. The first report 

resulting from these investigations was Bulletin 18 ' 

of the Arkansas Division of Geology entitled, Geological formations penetrated by the ArkansasLouisiana Gas Co. no. 1 Barton well on the Cecil anticline, Franklin County, Ark.,by R. J. Lantz. A 

second report, a map of the Oil and Gas Investigations 

Series of the U. S. Geological Survey entitled, Geology 

of the Gilbert area, Searcy County, Ark., by J. C. 

Maher and R. J. Lantz, is now in press. This report 

presents a detailed surface map of lower Paleozoic 

rocks of a small area north of the Boston Mountains 

where numerous small structural features are present. Detailed descriptions of measured sections and 

the well cuttings of the Marshall water well presented 

in this circular may be useful in establishing subsurface correlations in the Arkansas valley.

Detailed descriptions of the surface sections in 

this report are based on samples taken where each 

formation is best exposed and, if possible, where 

each formation is best developed. Location of these 

sections is shown on figure 1. In some places, 

satisfactory samples could not be obtained where the 

formations are thickest, and, as a result, some sections do not represent the maximum thickness of the 

beds within the area. Vertical intervals were measured by hand level and tape, marked, and numbered 

on the outcrops. Correspondingly numbered channel 

samples were then taken of the interval. The outcrops were examined and described fully in the field 

with special emphasis on bedding and weathering. 

The samples were then crushed, washed, and examined in the office with the aid of a binocular microscope. The sections included in this report combine 

the microscopic and field descriptions.

In addition, the sample descriptions were 

plotted on a log strip on a scale of 1 in. equals 100 

ft. Colors were used to indicate the general lithology; symbols to indicate details of the lithology; and 

detailed descriptions of the samples were lettered 

along the side of the log opposite the position of the 

corresponding sample. This permitted easy 

comparison with the sample log of the Marshall 

water well, which was drilled with cable tools.

The terminology used in the description of the 

samples is essentially that used by most midcontinent geologists making microscopic examinations 

of well samples. The terms given below are used in 

accordance with the Wentworth Grade Scale:

Silt, 0. 0038 mm to 0.062 mm in diameter. 

Very fine grained sandstone, 0. 062 mm to

0.125 mm in diameter. 

Fine-grained sandstone, 0.125 mm to 0. 25

mm in diameter. 

Medium-grained sandstone, 0. 25 mm to

0. 50 mm in diameter. 

Coarse-grained sandstone, 0. 50 mm to 1.00

mm in diameter. 

Very coarse grained sandstone, 1.00 mm to

2. 00 mm in diameter.
A limestone or dolomite which has rough texture is considered "crystalline" if crystal faces 

may be seen; if crystal faces are absent, it is 

termed "granular. " A limestone or dolomite which 

has smooth texture is called "dense. "

The bedding was described as follows:

Fissile, less than 1/16 in. thick. 

Platy, 1/16 in. to 1/2 in. thick. 

Very thin bedded, 1/2 in. to 2 in. thick. 

Thin-bedded, 2 in. to 4 in. thick. 

Medium-bedded, 4 in. to 12 in. thick. 

Thick-bedded, 12 in. to 36 in. thick. 

Massive, more than 36 in. thick.

The National Research Council rock-color 

chart was not used in the descriptions.

The investigations in northern Arkansas have 

been aided immensely by H. D. Miser of the U. S.

Geological Survey, who has given generoasly of Ms 

t ime and experience in checking correlations and 

mapping. N. F. Williams, director, H. B. Foxhall, 

former director, and C. A. Renfroe of the Division 

of Geology, Arkansas Resources and Development 

Commission, extended many courtesies including the 

loan of the Marshall water-well samples and the use 

of a rock crusher Josiah Bridge, Mackenzie Gordon, Jr., Helen Duncan, W. H. Hass, and Jean M. 

Berdan of the U. S. Geological Survey identified the 

fossils collected during the field work. Mackenzie 

Gordon, Jr., spent several days examining Mississippian rocks in the area and suggested the correlations at Pate Mountain (section J in this report). 

Jackson King aided the writers in sampling the outcrops.

The classification and thickness of the Paleozoic 

rocks at Gilbert, Carver, and Marshall are given in 

the table below.

Classification and thickness of Paleozoic rocks at Gilbert, Carver, and Marshall, Ark.

System

Carboniferous 

(Mississippian)

Silurian

Ordovician

*

Formation

Batesville sandstone

Ruddell shale

Moorefield formation

Boone formation

Chert-bearing units

St. Joe limestone member

Basal sandstone member

Lafferty limestone

St. Clair limestone

Brassfield limestone

Cason shale

Fern vale limestone

Plattin limestone

St. Peter sandstone

Everton formation

Powell(?) limestone

Cotter(?) dolomite

Jefferson City(?) dolomite

Roubidoux(?) formation

Gasconade(?) dolomite

Thickness

Gilbert

Ft

32

17

1

355 ±

343 i

9

2

30

34

25

13

25

75

32

-

-

-

-

-

-

in.

11

7

2

0

0

3

6

1

5

11

0

i

4

4

--

--

Carver

Ft in.

 

 

 

9

9

13 2

1 7

6 11

32 7

75 7

Marshall

Ft

9

9

9

3TS

347

26

2

1 6

i 5

14

12

66

44

595(?)

215(?)

350(?)

350(?)

266(?)

9
REPRESENTATIVE MEASURED SECTIONS 

OF PALEOZOIC ROCKS

A. Everton formation

[ Section measured at small dome on Bear Creek near 

center sec. 5, T. 15 N., R. 16 W., Searcy County, 

Ark.]

Plattin limestone.

Everton formation:

-Et

Dolomite, massive, buff to graybuff, finely granular, with pinpoint porosity; contains scattered

rounded and frosted medium- sized

sand grains .................... 5 6

Covered interval .................. 4 10

Dolomite, massive, buff to dark

gray-buff, finely granular, with a

few pockets of medium- crystalline

calcite and scattered rounded and

frosted medium- sized sand

grains ......................... 4 9

Dolomite, massive, buff to dark

gray-buff, finely granular to

finely crystalline, with little

intercrystal porosity; contains

scattered rounded and frosted

medium- sized sand grains. ....... 9 10

Covered interval .................. 10 8

Dolomite, massive, buff, finely

granular; contains scattered

rounded and frosted mediumsized sand grains ............... 4 3

Covered interval .................. 5 8

Dolomite, thick-bedded, buff to

gray-buff, finely granular, with

veins of very coarsely crystalline calcite; contains scattered

rounded and frosted mediumsized sand grains ............... 3 2

Dolomite, massive, dark gray-buff,

very finely granular, which contains scattered rounded and

frosted medium- sized sand

grains; and buff sandy dolomite

in which the sand grains are

medium to coarse, rounded,

and frosted ..................... 5 6

Dolomite, massive, buff, sandy,

in which the sand grains are

medium to coarSe, rounded, and

frosted; and dark gray-buff finely

granular dolomite, which contains veins of very coarsely crystalline calcite and scattered

medium- sized rounded and

froste'd sand grains. .............. 5 3"

 overed.

B. St. Peter sandstone

[Section measured on north bank of Brush Creek 

near south end of railroad bridge across Buffalo 

River near center Si sec. 28, T. 16 N., R. 16 W., 

Searcy County, Ark. J

Plattin limestone.

St. Peter sandstone:

Ft in.

Sandstone, very thin to thinbedded, gray to buff, dolomitic, 

with medium-sized rounded and 

frosted grains, and some 

scattered very coarse rounded 

and frosted grains ............. 1 0

Covered interval ................. 4 9

Sandstone, thick-bedded, gray, 

dolomitic, fine- to mediumgrained; dark-gray, finely granular dolomite containing scattered 

fine rounded and frosted sand 

grains; and a few coarsely crystalline calcite veins ........... 1 11

Sandstone, thick-bedded, darkbuff, dolomitic, with fine- to 

medium-sized rounded and 

frosted grains, grading downward into white (weathering 

brown) sandstone with mediumsized rounded and frosted 

grains ........................ 2 3

Covered interval ................. 3 1

Sandstone, medium-bedded, white 

(weathering brown), with fineto medium-sized grains; most 

grains show crystal faces of 

secondary quartz .............. 13 10

Sandstone, thin- to mediumbedded, white (weathering 

brown), with medium-sized 

grains and some scattered very 

coarse grains; most grains show 

crystal faces of secondary 

quartz ........................ 5___6

Everton formation.

C. Plattin limestone

[ Section measured along railroad cut along north 

bank of the Buffalo River in SEiSWi sec. 29, T. 

16 N., R. 16 W., Searcy County, Ark. ]

Fern vale limestone. 

Plattin limestone:

Limestone, massive, light-buff, 

very finely crystalline to dense; 

contains a few scattered small 

caleite crystals ................ 5 i
Plattin limestone --Continued

Ft in.

Siltstone, deeply weathered,

massive, brown, limy, and very

fine grained sandstone. Some

khaki-colored, silty limestone at

top ............................ 5 1

Limestone, thin- to medium-bedded, 

pink-mottled light-buff, very finely 

crystalline to dense; contains stylolites and scattered small calcite 

crystals ....................... 3 6

Limestone, thin-bedded, gray to 

gray-buff, dense; contains scattered small calcite crystals ...... 4 9

Limestone, thin- to medium-bedded, 

light gray-buff, dense; contains 

a few scattered small calcite 

crystals ....................... 4 0

Limestone, thick-bedded, gray to 

light gray-buff, dense; contains 

very few scattered small calcite 

crystals ....................... 2 3

Limestone, massive, light-buff, 

dense; contains a few scattered 

small calcite crystals and very 

small calcite veins .............. 5 4

Limestone, medium-bedded, graybuff, dense; contains a few 

scattered small calcite crystals 

and pyrite crystals ............. 1 0

Shale, fissile, gray to gray-green, 

and platy gray dense limestone, 

in alternating beds; limestone 

contains a few scattered small 

calcite crystals ................. 1 3

Limestone, thick-bedded, light 

gray-buff, dense; contains 

scattered small calcite crystals, 

stylolites, and pyrite ............ 1 2

Limestone, thick-bedded, light 

gray-buff to light-buff, dense; 

contains a few scattered small 

calcite crystals ................. 2 7

Shale, platy, gray, limy ........... 3

Limestone, thick-bedded, light-buff, 

dense; contains a few scattered 

small calcite crystals ........... 1 7

Limestone, very thin bedded, lightbuff, dense; contains a few scattered small calcite crystals ...... 6

Shale, platy, gray-green, limy ..... 2

Limestone, massive, light graybuff, dense; contains scattered 

small calcite crystals ........... 3 6

Limestone, platy to thin-bedded, 

buff, very finely crystalline to 

dense; contains scattered small 

calcite and pyrite crystals ....... 4 6

Limestone, massive, buff, very 

finely crystalline to dense; contains a few scattered small calcite 

and pyrite crystals .............. 4 0

Limestone, platy to medium-bedded, 

buff to gray, dense; contains 

scattered small calcite and pyrite 

crystals ....................... 1 10

Plattin limestone Continued

Ft in.

Limestone, platy to thin-bedded, 

gray to gray-buff, very finely 

crystalline to dense; contains 

scattered small calcite and 

pyrite crystals ................. 3 3

Limestone, thin- to medium-bedded, 

gray to gray-buff, figured, finely 

granular to dense; appears as 

rounded fragments of dense limestone in dense limestone matrix .. 2 1

Limestone, very thin bedded to 

thin-bedded, light-gray to light 

gray-buff, dense; contains 

scattered small calcite and pyrite crystals ................... 2 6

Shale, platy, yellowish-gray to

tan, limy, and shaly limestone ... 8

Limestone, very thin to mediumbedded, light-gray to gray-buff, 

dense; contains scattered small 

calcite crystals ................. 5 6

Limestone, thick-bedded, light graybuff, dense; contains scattered 

small calcite and pyrite crystals .. 1 5

Limestone, rubbly, gray, figured, 

dense; appears to be composed 

of rounded pebbles and angular 

blocks of gray, dense limestone 

in gray dense limestone, matrix ... 1 6

Limestone, thick-bedded, light 

gray-buff, dense; contains 

scattered small calcite crystals .. 1 4

Limestone, very thin bedded to 

thin-bedded, light gray-buff, 

dense; contains scattered small 

calcite crystals ................. 2 1

Limestone, medium-bedded, gray, 

very finely crystalline to dense; 

contains scattered medium-sized 

rounded and frosted sand grains .. 7

Dolomite, medium-bedded, graybuff, finely granular............. 1 1

Dolomite, medium-bedded, graygreen, finely granular; contains 

scattered fine- to medium-sized 

rounded and frosted sand grains; 

a few coarse rounded and frosted 

sand grains at the base .......... 10

75

St. Peter sandstone.

D. Fernvale limestone

[ Section measured along railroad cut along north 

bank of the Buffalo River in SEiSWi sec. 29, T. 

16 N., R. 16 W., Searcy County, Ark. ]

Cason shale. 

Fernvale limestone:

Limestone, thick-bedded, lightgray, very coarsely crystalline; 

contains limonite and pyrite blebs 

and scattered pale-pink calcite 

fragments ...................... 1 I
Fernvale limestone --Continued

Limestone, massive, pinkishbuff to cream-colored, very 

coarsely crystalline; contains 

pale-pink calcite fragments ....

Limestone, massive, weathering 

rubbly, pinkish-buff, very 

coarsely crystalline ...........

Limestone, thick-bedded, weathering rubbly, pinkish-buff to 

light-gray, very coarsely crystalline; contains a few limonite 

and pyrite blebs ..............

Limestone, thick-bedded, weathering rubbly, pink, coarsely crystalline to very coarsely 

crystalline; contains limonite 

and pyrite blebs, and many palepink calcite fragments .........

Limestone, massive, pinkishgray, coarsely crystalline to 

very coarsely crystalline;" 

contains many pale-pink calcite 

fragments ....................

Ft in.

Plattin limestone.

3 0

3 10

_5__6_ 

25 1

E. Cason shale 

[ Section measured near railroad crossing in

sec. 31, T. 16 N., R. 16 W., Searcy County, Ark. 

Fossil determinations by Josiah Bridge]

Basal sandstone member of Boone formation.

Cason shale:

Ft in.

Clay shale, platy, green to khakicolored ........................ 2 0

Shale, platy, khaki-colored,

slightly limy; contains scattered 

large phosphate nodules as much 

as 2 in. in diameter. Unidentifiable fragments of large sponge, 

Raphistoma sp., Cyclonema 

daytonensis Foerste?, CycToceras? sp., and some nodular 

material that may be fragments 

of algae. ....................... 7 6

Clay shale, platy, black and tan

mottled to green ................ 2 3

Shale, platy, khaki-colored; contains abundant phosphate 

nodules ........................ 1 3

Fernvale limestone. 13 0

F. Brassfield limestone

[Section measured on north bank of Bear Creek 

about 1 mile from mouth. NW|SEi sec. 32, T. 16 

N., R. 16 W., Searcy County, Ark. Fossil determinations by Jean M. BerdanJ

St. Clair limestone.

Brassfield limestone: Ft in.

Calcite, orange and white, very 

coarsely crystalline, and 

crinoid fragments poorly 

cemented by red to red-buff 

very finely crystalline limestone; contains limonite and 

pyrite blebs, irregular veins 

and vugs lined with white to clear 

coarsely crystalline calcite, and 

some very thin irregular 

stringers of red very finely crystalline limestone. Rhinopora 

verrucosa Hall, Triplecia cf. 

T. ortoni (Meek), Plectod'onta? 

sp., large strophomenoid impression, brachiopod fragments, 

simulated cephalopod, lichad 

trilobite pygidium, trilobite 

fragments, Bythocypris sp., 

thlipsurid ostracode, and Tubulibairdia? sp. .................... 7 10

Calcite, orange-red, orange, and 

white, very coarsely crystalline, 

and crinoid fragments poorly 

cemented by red very finely 

crystalline to dense limestone; 

contains limonite and pyrite 

blebs, irregular veins and 

vugs lined with white to clear 

coarsely crystalline calcite, 

and some irregular stringers 

and pockets of red very finely 

crystalline to dense limestone. 

Unidentifiable cup coral, 

Rhinopora verrucosa Hall, 

Dolerorthis cf. D. interstriata 

(Foerste), Leptaena rhomboidalis 

(Wilekens), Platystrophia sp., 

Rhipidomella cf. R. hybrida 

(Sowerby), small orthoid, fragment of punctate orthoid, other 

brachiopod fragments, unidentifiable cephalopod fragment, 

Encrinurus ? pygidium, Illaenus 

pygidium, fragments of a large 

illaenid trilobite, other trilobite 

fragments, and Bythocypris sp. . 10 0
Brassfield limestone --Continued

Calcite, orange-red, orange, 

and white, very coarsely crystalline, and crinoid fragments poorly cemented by red 

very finely crystalline to 

dense limestone; contains 

glauconite, limonite, and pyrite blebs, irregular veins 

and vugs lined with white to 

clear coarsely crystalline 

calcite, and some thin 

irregular stringers of red 

very finely crystalline to 

dense limestone. Unidentifiable horn coral, Rhinopora 

verrucosa Hall, Leptaena 

rhomboidalis (Wllckens), 

and illaenid trilobite fragments .....................

Covered interval ..............

Ft in.

Cason shale.

25 11

NOTE. --Bedding of Brassfield limestone masked by 

secondary deposition on face of bluff--the whole 

interval appears as one massive bed.

G. Lafferty and St. Clair limestones 

[ Section measured on north bank of the Buffalo River 

in approximate center Ei sec. 36, T. 16 N., R. 17 

W., Searcy County, Ark. ]

Basal sandstone member of Boone formation. 

Lafferty limestone:

Limestone, medium- to thickbedded, gray, pyritic and 

limonitic, very finely crystalline to dense, with 

scattered orange mediumsized calcite crystals ........... 6 2

Limestone, thick-bedded, gray, 

pyritic and limonitic, very 

finely crystalline to dense, 

which contains scattered orange 

medium-sized calcite crystals; 

and a few vugs lined with white 

coarsely crystalline calcite ...... 6 1

Limestone, massive, orangemottled gray to gray-buff, 

pyritic and limonitic, very 

finely crystalline to dense, with 

scattered orange medium-sized 

calcite crystals ................ 5 5

Limestone, massive, orangemottled gray-buff, pyritic, 

medium-crystalline to dense ..... 5 0

Limestone, massive, gray-buff 

to orange-buff, pyritic, very 

finely crystalline to dense, with 

pinkish-orange coarse calcite 

crystals and crinoid fragments.... 7 5

30 1

St. Clair limestone:

Covered interval I/ ...........

Calcite, pink, orange, and 

white, coarsely crystalline, 

and crinoid fragments cemented by tan-buff to orangebuff very finely crystalline 

limestone; contains irregular 

veins and vugs lined with 

white coarsely crystalline 

calcite. Some thin irregular 

layers show a predominance 

of the very finely crystalline 

cementing material..........

Ft

Brassfield limestone.

24

34

H. Upper part of Boone formation 

[Section measured along U. S. Highway 65 at Silver

Hill, SWi sec. 7 and NWi sec. 18, T. 15 N., R.

16 W., and SE| sec. 12, T. 15 N., R. 17 W., 

. Searcy County, Ark. Fossil determinations by

Mackenzie Gordon, Jr. Corals and bryozoans by

Helen Dune an]

Batesville sandstone and Ruddell shale, uHdiiie*eatiated.

Boone formation:

Covered interval .................. 21 11

Chert, thin- to medium-bedded, 

white to light-gray (weatherlag 

red), porous, spicular, finely 

figured; very small drusy 

quartz crystals lining some 

cavities ........................ 11 5

Chert, thin- to medium-bedded, 

white (weathering tan to red), 

porous, spicular, finely 

figured, tripolitic ............... IS 1

Covered interval .................. 36 2

Limestone, medium- to thickbedded, cream-colored 

(weathering gray), coarsely 

to very coarsely crystalline, 

crinoidal; contains irregular 

lenses and layers of white 

(weathering tan) siliceous limestone or limy chert. The 

coarsely crystalline limestone 

weathers to a very rough surface, 

which shows cross-bedding ...... 24 3^

Covered interval.................. 8 4|

Limestone, thick-bedded, lightgray, coarsely crystalline, 

erinoidal; weathers to rough 

surface, which shows crossbedding ........................ 8 11

1 A11 bedding below this covered interval IB masked by secondary deposition on face of bluff.
Boone formation --Continued

Ft in.

Limestone, massive, light-gray,

slightly glauconitic, coarsely

crystalline, crinoidal;

weathers to rough surface,

which shows cross-bedding.

Fenestella sp., Orthotetes sp.,

Rhipidpmella (Perditocardinia)

sp'. A?, Spirifer cf. S. grimesi Hall, and Spirifer cf. S.

logani Hall...................... S> 6

Limestone, massive, light-gray,

coarsely crystalline, crinoidal;

weathers to rough surface,

which shows cross-bedding;

contains irregular lenses of

white (weathering tan) siliceous

limestone or limy chert,

averaging about 2 ft long and

4 in. thick ..................... 11 0

Limestone, massive, light-gray,

slightly glauconitic, coarsely

crystalline, crinoidal; weathers

to rough surface, which shows

cross-bedding; contains

irregular lenses of white

(weathering tan) siliceous

limestone or limy chert ......... 5 6

Limestone, massive, light-gray

to buff, glauconitic, coarsely

crystalline; weathers to rough

surface, which shows crossbedding;- contains thin irregular

lenses of white (weathering tan)

siliceous limestone or limy

chert Fenestella sp., rhomboporoid bryozoan piatycrinitid

columnal, Productus sp.,

Rhipidomella (Perditocardinia)

sp. A., Rhynchopora sp. A?,

Dielasma sp., and Spirifer

togani Hall...................... 11 0

Limestone, massive, light-gray,

coarsely crystalline, crinoidal,

with scattered pink calclte

crystals to buff mediumcrystalline limestone; weathers

to rough surface, which shows

cross-bedding; contains

irregular lenses of white

(weathering tan) siliceous limestone or limy chert. Rhipi -

domella (Perditocardinia) sp. A,

RhyncEopora sp. A, Rhynchopora

sp. A?, and Spirifer logani Hall? . 5 6 

Limestone, thick-bedded, lightgray, glauconitic, coarsely

crystalline; weathers to rough

surface, which shows crossbedding Fistuliporoid bryozoan fragment, Rhipidomella

(Perditocardinia) sp. A?, and

Spirifer logani Hall.............. 3 1

Limestone, thin-bedded, white

(weathering tan), siliceous;

or limy chert ................... 1 6

Boone formation Continued

Ft in.

Limestone, thick-bedded, lightgray, glauconitic, coarsely 

crystalline, crinoidal; weathers 

to a rough surface, which shows 

cross-bedding .................. 6 5

Limestone, thick-bedded, lightgray, slightly glauconitic, 

coarsely to medium-crystallise, 

crinoidal; weathers to rough 

surface, which shows,crossbedding. Rhombopora sp., 

RhipidomeTIa (Perditocardinia) 

sp. A, Rhynchopora sp. A?, 

and Spirifer logani~Hall ........... 5 i

Covered interval .................. 5 6

Limestone, siliceous, massive 

light gray-buff, slightly glaueonitic, coarsely to mediumcrystalline, grading to limy chert.. 5 6

Chert, massive, white (weathering 

tan), glauconitic, spicular, 

limy ........................... § 6

Limestone, gray-buff (weathering 

dark-gray), glauconitic, mediumcrystalline in irregular lenses 

and thin irregular beds, which 

are in buff-spotted white glauconitic spicular figured limy 

chert .......................... 11 0

Chert, thin- to medium-bedded, 

buff-spotted white (weathering 

tan), slightly glauconitic, limy, 

with irregular lenses and 

bands of gray (weathering 

dark-gray) glauconitic 

medium-crystalline limestone .... 27 6

Limestone, very irregularly 

bedded and banded, gray-buff, 

glauconitic, medium-crystalline 

and buff-spotted white (weathering tan) glauconitic limy chert. 

Zaphrentoid coral, Fenestella 

sp., Orthotetes sp., Chonetes 

sp., Productus sp., Avonia 

williamsiana Girty, Schizophoria 

sp., Rhynchopora? sp., Spirifer 

logani Hall?, Cranaena? sp., 

Tylothyris? sp., Brachythyris 

suborbiciiTaris (Hall), arid 

Griffithideiysp. ................ 10 0

Limestone, thin-bedded, buff,

medium-crystalline ............. 1 0

Covered interval ................. 9 2

Limestone, very irregularly 

bedded, buff to gray-buff, 

medium-crystalline, dolomrtie; 

contains irregular lenses of 

buff-spotted white (weatheriag 

tan) spicular limy chert containing rhomb molds ............ 2T 6

Chert, irregularly bedded, teuffspotted white (weathering tan), 

limy; contains irregular lenses of 

gray-buff slightly glauconitic 

medium-crystalline limestone. 

Fenestella sp., Productus 

(DictyocTostus) crawfordtevUlensis 

Weller ................V....... 3 8
Boone formation --Continued

Covered interval ................

Chert, irregularly bedded, buffspotted white, limy; contains 

thin lenses of gray-buff mediumcrystalline to finely crystalline 

limestone ....................

Chert, irregularly bedded, white 

to light-gray, spicular, dense; 

contains irregular lenses of 

light gray-buff mediumcrystalline to finely crystalline limestone ................

Chert, irregularly bedded, graywhite, spicular, dense. 

Productus (Dictyoclostus) 

crawfordsvillensis Weller ? ...

Total thickness exposed

Ft in.

~1 ID"

11 0

11 0

5 6

316 10

I. Lower part of Boone formation 

[ Section measured near U. S. Highway 65 bridge 

across Bear Creek in SWi sec. 17, T. 15 N., R. 

16 W., Searcy County, Ark. 1

Boone formation (approximately a continuation of 

Silver Hill section (H) as shown by tracing beds 

about i mile along U. S. Highway 65.):

Chert-bearing units:

Chert, irregularly bedded, 

white to pale-pink, spicular; 

few very thin irregular 

beds of cream-colored 

finely crystalline limestone ..................... 11 0

Chert, thin- to mediumbedded, white to palepink, spicular; very thin 

beds of cream-colored 

finely crystalline limestone ..................... 5 6

Chert, irregularly bedded, 

white to pale-pink, 

spicular; contains irregular lenses of creamcolored finely crystalline limestone ............. 5 6

Limestone, irregularly 

bedded, pinkish-gray to 

buff, slabby to rubbly, 

finely crystalline; contains 

some white to pale-pink 

spicular chert ............ 4 0

26 0

St. Joe limestone member:

Limestone, thin- to mediumbedded, orange-buff, 

finely crystalline; contains red to pink coarsely 

crystalline fragments of 

crinoids .................

Boone formation. --Continued

St. Joe limestone member --Continued

Ft

Limestone, thin- to 

medium-bedded, lightgray to orange-buff, 

pyritic, finely crystalline; contains red to 

pink coarsely crystalline 

fragments of crinoids ...... 5

Basal sandstone member:

Sandstone, thin-bedded, 

brown, slightly limy, 

medium- to coarsegrained, with Taonuruslike markings on top surface .......................

W. H. Hass regards this 

part of the sandstone as 

Mississippian (Kinderhook) 

in age on basis of his 

conodont identifications.

Sandstone, medium-bedded, 

brown, medium-grained .... 

W. H. Hass regards this 

lower part of the sandstone 

as Late Devonian (preGrassy Creek) in age on the 

basis of his conodont identifications.

J. Batesville sandstone, Ruddell shale,

and Moorefield formation

[Section measured at Pate Mountain, NWi sec. 23, 

T. 15 N., R. 17 W., Searcy County, Ark. Fossil 

determinations by Mackenzie Gordon, Jr. ]

Fayetteville shale. 

Batesville sandstone:

Limestone, thin-bedded, dark-gray,

very fine to fine, sandy; few

medium-sized oolites. Bryozoan

indet., Fenestella sp., crinoid

columnals, Composita? sp.

indet., and gastropod? indet. .... 1 7 

Sandstone, thin-bedded, gray

(weathering grayish-tan), limy,

very fine to fine-grained ......... 4 10

Limestone, thin-bedded, dark-gray,

finely granular. Bryozoan?

indet., Productus (Diaphragmus)

cestriensis Worthen, Dielasma

ilTmoisensis Weller?, brachiopods indet.., and ostracodes ...... 8

Clay shale, platy, khaki-colored

to tan, slightly limy ............. 1 9

Limestone, thick-bedded, gray

(weathering grayish-tan), dense,

silty; breaks with conchoidal

fracture ....................... 2 0
Batesville sandstone --Continued

Ft in.

Clay shale, platy, khaki-colored; 

very fine, sandy, with black 

stain on bedding planes .......... 10

Limestone, medium-bedded, gray, 

dense, slightly silty; contains 

scattered fine calcite crystals; 

breaks with conchoidal fracture ........................... 7

Clay shale, platy and crumbly, 

khaki-colored to tan; contains 

a few limy nodules .............. 2 11

Limestone, thin-bedded, light 

pinkish-tan, dense, silty;

. weathers rubbly ................ 8

Sandstone, platy, gray, limy,

very fine to fine-grained ......... 1 9

Sandstone, platy, tan, shaly,

very fine grained ............... 1 0

Sandstone, thick-bedded, light 

grayish tan, very fine to finegrained, limy .................. 2 0

Shale, platy, tan, slightly limy, 

silty; thin layers of tan very fine 

grained limy sandstone .......... 9

Limestone, medium-bedded, darkgray, medium-crystalline, 

very fine, sandy, with mediumsized oolites, some of which 

are elongate .................... 1 0

Siltstone, medium-bedded, tan 

to brown, limy, and very fine 

grained sandstone ................ 7

Shale, platy, tan, slightly limy, 

silty; thin layers of tan very 

fine grained limy sandstone. 

Crinoid columnals, Agassizocrinus plates, Orthotetes subglobosus Girty,~Leiorjijfnchus 

carboniTerum Girty and brachiopods indet. ..................... 1 0

Sandstone, medium-bedded, gray 

(weathering tan), very fine to 

fine-grained, very limy ......... 1 2

Shale, platy, tan, micaceous, 

silty, and thin-bedded, tan 

very fine grained shaly sandstone in alternating beds ......... 4 4

Limestone, medium-bedded, gray, 

medium-crystalline, with a 

few medium-sized oolites; very 

fine, sandy at base. Crinoid 

columnals, Agassizocrinus 

plates, ? Productus (£)ia~ 

phragmusfcestriensis Worthen, 

Productus (Echinoconchus) 

cf. E. genevievensis Weller, 

Dielasma sp., brachiopods 

indet., and small gastropods 

indet. ...................... i.. 1 6

Shale, platy, tan, micaceous,

slightly limy, silty. Aviculopecten

sp. and Laevidentalium venustum

Meek and Worthen r ............. 1 0

Batesville sandstone Continued

Sandstone, medium-bedded, gray 

(weathering brown), very limy, 

fine-grained .................

Ft in.

Ruddell shale:

Shale, platy to fissile, grayblack and tan, micaceous, 

slightly silty .................... 4 3

Shale, platy to fissile, grayblack, micaceous Caneyella

nasuta Girty?, Goniatites 

' kentuckiensis Miller and

Gurley, and Girtyoceras sp....... 5 6

Shale, platy, tan to interlaminated black and tan, limy, very

fine, sandy. Chonetes cf. C.

tumescens Easton, Camarotoechia purduei Girty, and COmppsita~s ubquadrata (Hall) ? ....... 2 4

Shale, platy, gray-black

(weathering brown), slightly

micaceous, limy ................ 1 0

Sandstone, platy, tan grading

downward into gray, very fine

grained, limy and shaly.......... 1 0

Limestone, medium-bedded, gray,

finely crystalline, very fine,

sandy. Mackenzie Gordon, Jr.,

regards this bed as Ruddell in

age on basis of the following

fossil identifications by him:

Fenestella sp., Lingula sp.

indet., Orbiculoidea marshal -

lensis (Girty), Chonetes cf. C.

tumescens Easton, Productus

sp. indet;, Camarotoechia

purduei Girty, LeiorhyncFus

carboni'ferum Girty, Leiorhynchus

carboniferum polypleurum Girty,

Eumetria vera (Hall), Comppsita

cf. C. acinus Girty, Conularia

sp. indet., and ostracodes ....... 6

Shale, platy, tan, very fine, sandy

and limy; limy nodules .......... 3 0

17

Moorefield formation:

Limestone, very thin bedded, darkgray, finely granular to finely 

crystalline, silty. Mackenzie 

Gordon, Jr., reports that this 

bed apparently represents the 

Moorefield formation as restricted by him in A. A. P. G. 

Bull., vol. 28, no. 11, pp. 

1626-1634, 1944. He identified 

the following fossils: Leiorhynchus carboniferum Girty, 

Aviculopecten cf. A.~Fatesvillensis (Girty), Sphenotus, 

and ostracodes .................
K. Carboniferous (Mississippian) 

and Ordovician rocks

[Section measured at Carver near the north end of 

the Buffalo River bridge on State Route 123, 

sec. 6, T. 15 N., R. 19 W., Newton County, 

Ark. 1

Carboniferous (Mississippian) rocks:

Boone formation (lower part only; 

estimated 150 to 200 ft present 

in cliff):

Chert-bearing units (from 

top of St. Joe limestone to 

top of measured section):

Chert, irregular, thin 

to medium thick, gray, 

finely pyritic, dense, 

in layers separated 

by very thin bedded 

buff finely crystalline 

limestone............

Shale, platy, greenishbuff, limy; contains 

small pebbles of gray 

dense chert ..........

Chert, thin-bedded, 

light-gray to buff, 

finely figured, dense; 

contains buff finely 

crystalline limestone pebbles ........

Shale, platy, very limy, 

greenish-buff; contains ostracodes......

Chert, thin-bedded, 

gray-buff, finely 

figured, dense, and 

buff finely crystalline 

 limestone............

Chert, thin beds of 

dark-gray to black, 

dense; maroontinged brown dense 

chert; and buff finely 

crystalline limestone ...............

Limestone, very thin 

bedded, buff, finely 

crystalline to dense; 

contains some small 

white calcite crystals ................

Ft in.

1 0

9 6

St. Joe limestone member of the 

Boone formation:

Limestone, thinbedded, reddishbuff, finely 

crystalline; contains 

abundant fossil 

fragments and calcite crystals .........

Limestone, thin-bedded, 

pinkish-buff, crinoidal, 

coarsely crystalline; 

thin bed of buff-brown 

very finely crystalline 

limestone at base ....

Carboniferous (Mississippian) rocks --Continued 

Boone formation --Continued

St. Joe limestone member --Continued

Ft in.

Limestone, thin- and 

irregular-bedded, 

reddish-buff, finely 

to coarsely crystalline; 

contains abundant 

small crinoids and 

white calcite crystals . 4 2

Limestone, thin- and 

irregular-bedded, 

buff, finely crystalline; contains abundant 

red calcite crystals 

and a few very thin 

seams of greenishbuff shale ........... 3 9

Shale, platy, green, 

sandy; contains 

black phosphate pellets and red calcite 

crystals ............ ______1_

13 2

Basal sandstone member of 

Boone formation:

Sandstone, thin-bedded, 

white, limy, composed of mediumsized round to subround slightly 

frosted quartz grains. 

Black phosphate 

pellets are scattered 

throughout the sandstone ...............

W. H. Hass regards 

this bed and overlying 

bed as Mississippian 

(Kinderhook) in age 

on basis of his conodont identifications. 

Specimens from 

underlying beds were 

inconclusive.

Shale, fissile, grayishgreen ...............

Sandstone, greenishwhite, composed of 

white medium-sized 

subround quartz 

grains and green limy 

silt; abundant black 

phosphate nodules ....

Ordovician rocks:

Fernvale limestone:

Limestone, thin- and 

irregular-bedded, gray, 

medium to coarsely 

crystalline; contains 

pyrite cubes ........... 1 10

10
Ordovician rocks--Continued

Fernvale limestone--Continued

Ordovician rocks--Continued 

St. Peter sandstone:

Ft in.

Limestone, thin- and 

irregular-bedded, gray, 

pyritic, crinoidal, 

coarsely crystalline; 

weathers rubbly.........

Limestone, thin- to 

medium-bedded, graybuff, crinoidal, coarsely 

crystalline; crinoids 

are barrel-shaped.......

2 10

_ ~ rr

Plattin limestone:

Dolomite, medium-bedded,

yellowish-buff, slightly

black-mottled, finely

granular.................. 2 10

Dolomite, thin- to mediumbedded, dark-gray to

yellowish-buff, finely

granular.................. 2 4

Dolomite, thin-bedded, buff

to gray, finely granular,

and dolomitic limestone..... 1 10 

Dolomite, thin- and irregularbedded, gray-buff, finely

granular, with a resinous

luster; gray-buff finely

crystalline to dense

limestone; very thin seam

of tan very fine grained

sandstone, in lower part.... 2 11

Covered interval. ............. 1 1

Limestone, thin- to thickbedded, gray-buff,

slightly pink-mottled,

dense; contains gray-buff

dense chert................ 4 1

Limestone, thin- to mediumbedded, gray-buff, dense;

contains scattered small

calcite crystals............ 3 10

Limestone, thin- to mediumbedded, gray-buff, dense;

contains scattered small

calcite crystals............. 3 10

Limestone, thin-bedded,

tan to gray, shaly........... 11

Limestone, thin-bedded,

gray-buff, dense; contains

scattered small calcite

crystals................... 2 7

Limestone, very thin bedded,

gray-buff, dense ........... 4

Limestone, thin-bedded,

gray-buff, dense; contains

pink to orange spots and

scattered calcite crystals .... 2 9 

Limestone, very thin bedded,

gray-buff, dense, with

fine calcite veinlets ......... 1 7

Limestone, thin-bedded,

light-gray, sandy, dense,

grading upward into

nonsandy limestone ......... 1 8

Ft in.

Sandstone, soft, greenishwhite, very limy; composed of subround to 

round frosted fine- to 

medium-sized quartz 

grains...................... 2 6

Covered interval............... 3 3

Sandstone, thin-bedded, 

white, limy; similar in 

composition to that above ..... 4

Covered interval............... 2 4

Sandstone, thin-bedded, 

greenish-gray, slightly 

argillaceous, limy; similar 

in composition to that above ... 5

Dolomite, dull-gray, very 

finely granular, silty; contains very thin laminae of 

very fine grained sandstone ...................... 4 3

Sandstone, greenish-white, 

limy; similar in composition to the sandstones 

above...................... 4 6

Dolomite, gray-buff, very

finely granular.............. 7

Covered interval.............. 2 7

Sandstone, white, limy, fineto medium-grained ......... 4

Sandstone, thin-bedded, brown,

dolomitic, fine-grained...... 4 9

Covered interval ............. 3 0

Sandstone, thin-bedded, white 

to brown, dolomitic, finegrained .................... 2 5

Dolomite, very thin bedded, 

gray-buff, fine-grained; 

contains abundant round 

frosted fine sand grains ...... 4

Sandstone, medium-bedded, 

buff-brown, dolomitic, 

fine-grained, and white 

fine- to medium-grained 

sandstone................... 2 6

Covered interval .............. 8 1

Sandstone, soft, very thin 

bedded, pinkish- to greenishwhite, fine- to mediumgrained; grains exhibit 

secondary enlargement....... 2 5

Covered interval .............. 4 9

Sandstone, medium-bedded, 

white, limy, mediumgrained; grains exhibit 

secondary enlargement ....... 5 6

(Note: 1 beds below this sandstone 

are doubtfully included in 

the St. Peter sandstone 

pending completion of detailed mapping)

Dolomite, massive, darkgray to brown, mediumcrystalline to coarsely 

crystalline.................. 8 7

This note was omitted from the first printing.

11
Ordovician rocks --Continued

St. Peter sandstone --Continued

Sandstone, thin-bedded, 

white, fine- to mediumgrained; grains are 

rounded and frosted .....

Covered interval..........

Sandstone, medium-bedded, 

white, with fine- to 

medium-sized rounded 

and frosted grains ......

Covered interval..........

Ft in.

75

Everton formation:

Limestone, medium-bedded,

light-buff, slightly sandy,

finely crystalline .......... 1 3

Limestone, medium-bedded,

buff, finely crystalline ...... 11

Limestone, medium-bedded,

buff, sandy................ 8

Limestone, light-buff, oolitic,

or microfossiliferous,

finely crystalline; grades

downward into buff sandy

limestone ................. 1 1

Sandstone, medium-bedded,

white, very limy; composed

of medium-sized rounded

and frosted grains ......... 2 3

Limestone, medium- to

thick-bedded, buff, mediumcrystalline; contains scattered round sand grains

grading downward into

white limy fine-grained

sandstone ................. 1 11

Limestone, medium-bedded,

buff, finely crystalline

to dense .................. 5

Sandstone, greenish-white,

limy, fine-grained ......... 2

Dolomite, thin-bedded, brown,

medium-crystalline ........ 9

Covered interval ............ 2 9

Limestone, medium-bedded,

buff, microfossiliferous,

finely crystalline; abundant

ostracodes ................ 1 11

Limestone, medium-bedded,

light-buff, sandy, finely

crystalline ................ 1 9

Limestone, thin-bedded,

light-buff, sandy, finely

crystalline ................ 1 3

Limestone, thin-bedded,

light-buff, oolitic or microfossiliferous, dense;

calcite; round frosted sand

grains in upper part........ 1 4

Limestone, thin-bedded,

light-buff, oolitic or

microfossiliferous, sandy;

round frosted sand grains

increase upward ........... 1 0

Like overlying bed, but very

thin bedded ............... 1 2

Ordovician rocks --Continued

Everton formation --Continued

Ft in.

Limestone, thin-bedded, 

light-buff, finely figured, 

finely crystalline .......... 1

Covered interval.............

Limestone, thin-bedded, 

light-buff, finely figured, 

finely crystalline .......... 2

Sandstone, white, slightly 

limy, medium-grained; 

grains exhibit secondary 

enlargement...............

Sandstone, massive, white, 

medium-grained; composed 

of rounded and frosted 

grains .................... 2

Limestone, gray-buff,

microfossiliferous, finely 

crystalline; abundant 

ostracodes ................

Sandstone, thin- to mediumbedded, tan to white, fineto medium-grained; below 

water level usually ........ 3

10

7

31

LOG OF MARSHALL WATER WELL 3, 

MARSHALL, ARK.

[Sample log, SW^SEi sec. 25, T. 15 N., R. 16 W., 

Searcy County, Ark. Altitude of well about 1, 000 

ft. Cable tool samples]

Carboniferous (Mississippian) rocks:

Depth 

(feet)

Batesville sandstone and Ruddell shale 

shale, undifferentiated; no samples, 

but black shale cavings are present 

in first sample and above formations crop out nearby ............ 0-23

Boone formation:

Limestone, gray- mottled

buff, slightly glauconitic,

medium-crystalline;

buff dense chert ........... 23-27

Dolomite, pinkish-buff

to buff, finely crystalline ... 27-30 

Dolomite, pinkish-buff

to buff, finely crystalline ;

buff spicular chert ......... 30-35

Dolomite, cream-colored,

finely crystalline; tanmottled white dense

chert ..................... 35-40

Limestone, white, finely

crystalline; brachiopods .... 40-45 

Limestone, white, finely

crystalline ................ 45- 50

Dolomite, gray-white, finely

granular; some thin beds

of buff finely crystalline

dolomite ................... 50-51

Limestone, buff, finely

crystalline ................ 51-53

Dolomite, white, finely granular; small crinoids........ 53-60

12
Carboniferous (Mississippian) rocks --Continued 

Boone formation --Continued _ .,

(feet) Dolomite, white, finely v '

granular ................... 60- 70

Limestone, light-buff,

crinoidal, finely to

medium-crystalline ........ 70-75

Limestone, light-buff,

crinoidal, finely to

medium-crystalline;

trace of glauconite ......... 75-85

Limestone, light-buff,

crinoidal, finely to

medium-crystalline ........ 85-120

Dolomite, white, finely

granular, limy ............ 120-130

Limestone, light-buff, finely

crystalline; trace of white

milky chert ............... 130-133

Limestone, white, very

crinoidal, finely crystalline ...................... 133-140

Limestone, white, very

crinoidal, finely crystalline; brachiopods .......... 140-145

Limestone, cream-colored,

crinoidal.................. 145-150

Limestone, buff, finely to

medium-crystalline;

dull-white semi-granular

finely spicular chert ....... 150-155

Limestone, buff, finely

crystalline ................ 155-160

Dolomite, cream-colored,

limy; dull-white semigranular chert ............ 160-165

Dolomite, cream-colored,

finely granular; white

dense chert ............... 165-170

Dolomite, cream-colored,

finely granular ............ 170-175

Dolomite, cream-colored,

very finely glauconitic,

finely granular to finely

crystalline; pyrite;

spines .................... 175-180

Dolomite, cream-colored,

very finely glauconitic,

finely granular to finely

crystalline; spines ......... 180-185

Dolomite, white, finely

granular; white dense

chert; spines.............. 185-190

Dolomite, white, finely

granular; white semigranular chert ............ 190-200

Dolomite, bone-white,

very siliceous finely

glauconitic, finely

granular to finely crystalline ................... 200-204

Dolomite, bone-white, very

siliceous, finely granular

to finely crystalline ........ 204-240

Limestone, bone-white,

siliceous; white dense

chert ..................... 240-250

Limestone, bone-white,

siliceous ................. 250-265

Carboniferous (Mississippian) rocks --Continued 

Boone formation --Continued

Depth 

(feet)

Limestone, bone-white, 

siliceous; some white 

dense chert; pyrite ......... 265-275

Limestone, bone-white, 

siliceous; white spicular 

chert ..................... 275-290

Limestone, bone-white, 

siliceous; white spicular 

chert; slightly gray-white 

dense chert ............... 290-300

Limestone, bone-white, 

siliceous; white dense, 

chert ..................... 300-310

Limestone, cream-colored, 

finely crystalline; white 

dense chert ............... 310-326

Dolomite, white, finely 

granular; white dense 

chert ..................... 326-335

Dolomite, cream-colored, 

finely granular; graywhite dense chert .......... 335-350

Limestone, brown, finely 

granular to finely crystalline; gray-white to smoky 

dense chert with black 

inclusions ................ 350-365

Limestone, cream-colored, 

finely granular to finely 

crystalline; some creamcolored dense chert ........ 365-370^

St. Joe limestone member:

Limestone, white, 

chalky; little white 

dense chert .......... 370-375

Limestone, white, 

chalky; trace of very 

fine glauconite ....... 375-380

Limestone, white, 

chalky, with few fine 

round sand grains .... 380-384

Limestone, brown, 

pyritic, finely crystalline, with thin 

layers of dark-green 

finely glauconitic 

shale ............... 384-390

Limestone, gray-buff, 

pyritic, with abundant 

pink calcite crystals 

and crinoids ......... 390-396

Basal sandstone member: Gray 

subangular to subround 

pyritic sandstone .......... 396-398

Silurian rocks:

Lafferty and St. Clair limestones, 

undifferentiated:

Limestone, brown, finely 

crystalline; brown dense 

chert; brachiopods ......... 398-400

13
Silurian rocks Continued

Lafferty and St. Glair limestones, 

undifferentiated --Continued

Limestone, brown, finely 

crystalline ..............

Limestone, brown, finely 

crystalline, with pink 

calcite crystals; pyrite ...

Limestone, buff, finely 

crystalline,- with pink 

calcite crystals .........

Limestone, cream-colored 

to buff, finely crystalline, 

with pink calcite crystals; 

pyrite ..................

Limestone, buff, crinoidal, 

with pink calcite crystals; 

pyrite ..................

Limestone, white, finely 

crystalline, with pink 

calcite crystals; oolitoid 

objects .................

Limestone, white, finely 

crystalline ..............

Depth 

(feet)

400-410 

410-420 

420-425

425-430 

430-446

446-450 

450-454

Brassfield limestone member 

absent.

Ordovician rocks: 

Cason shale:

Sandstone, gray-green,

pyritic, glauconitic, slightly

limy, very fine .....*...... 454-455

Shale, black ................ 455-466

Shale, pale-green, pyritic, 

with black phosphate 

pellets ................... 466-468

Fernvale limestone:

Limestone, white, coarsely 

crystalline; tra'ce of pink 

calcite ................... 468-480

Plattin limestone:

Limestone, buff, finely crystalline ................... 480-490

Dolomite, buff-brown,

finely granular ............ 490-508

Dolomite, buff-brown,

finely crystalline .......... 508-510

Limestone, brown, finely

crystalline to dense ....... 510-533

Shale, gray, hard, limy ...... 533-535

Limestone, brown, finely

crystalline to dense ........ 535-546

St. Peter sandstone:

Sandstone, white, sobround, 

slightly frosted, slightly 

limy, fine-grained; 

pyrite .................... 546-550

Ordovician rocks --Continued

St. Peter sandstone --Continued

Sandstone, white, limy, 

pyritic, fine- to mediumgrained; grains are subround and frosted .......

Everton formation:

Limestone, white, finely 

crystalline ................

Dolomite, brown, sandy, 

finely granular. Dolomite 

has white subround 

medium-sized sand grains 

scattered in it .............

Sandstone, white, fine- to 

medium-grained, with 

subround and frosted 

grains ....................

Dolomite, buff, mediumcrystalline ................

Sandstone, white, finegrained ...................

Dolomite, brown, very finely 

granular, in part sandy; 

blue-green shale fragments; brown coarsely crystalline dolomite ..........

Dolomite, brown, finely 

granular to finely crystalline ......................

Dolomite, gray, slightly

silty, very finely granular ..

Dolomite, buff to brown, 

very sandy, mediumcrystalline; contains 

white subround mediumsized sand grains ..........

Dolomite, buff, very sandy 

(40- 50 percent sand)........

Dolomite, dark-brown, almost 

resinous, finely granular; 

trace of white mineral 

dolomite ..................

Dolomite, brown, finely to 

medium -crystalline; 

white calcite crystals ......

Dolomite, brown, finely

granular ..................

Dolomite, brown, mediumcrystalline ................

Dolomite, brown, fine,

sandy.....................

Sandstone, white, limy,

fine-grained ..............

Dolomite, brown, fine,

sandy ....................

Sandstone, white, fine- to 

medium-grained ...........

Dolomite, dark-brown,

finely granular ............

Sandstone, white, finegrained ...................

Dolomite, drab, shaly, and 

dolomitic mudstone ........

Depth 

(feet)

550-590 

590-592

592-606

606-607

607-616

616-617

617-620

620-628 

628-630

630-635 

635-644

644-650

650-657 

657-665 

665-670 

670-674 

674-676 

676-682 

682-684 

684-695

695-696

696-700

14
Ordovician rocks --Continued

Everton formation --Continued

Dolomite, brown, sandy; 

contains white subround 

medium-sized sand

grains ...................

Dolomite, dark-brown,

finely crystalline .........

Dolomite, brown, sandy

Sandstone, white, mediumgrained ..................

Dolomite, brown, finely 

crystalline ...............

Dolomite, brown, shaly, or 

dolomitic mudstone .......

Sandstone, tan, dolomitic, 

fine-grained, and 

white fine-grained sandstone with white silica 

cement ..................

Dolomite, brown, silty ......

Dolomite, buff-brown, very 

sandy....................

Sandstone, white, finegrained ..................

Dolomite, buff-brown, very 

sandy ...................

Dolomite, buff, finely granular .....................

Dolomite, buff, finely granular; some buff sandy 

dolomite .................

Dolomite, buff, sandy,

finely granular ...........

Dolomite, buff, very finely 

granular .................

Dolomite, buff, very finely 

granular, with some white 

calcite crystals ..........

Dolomite, very dark brown, 

finely granular ...........

Dolomite, very dark brown, 

finely granular; thin 

layers of black dolomitic 

shale .....................

Dolomite, brown, finely 

granular; calcite..........

Dolomite, buff, sandy .......

Dolomite, dark brown, finely 

granular .................

Dolomite, tan, very finely 

granular .................

Dolomite, tan to buff, sandy..

Dolomite, brown, finely 

crystalline ...............

Dolomite, buff, finely crystalline ..................

Dolomite, brown, finely 

granular .................

Sandstone, white fine- to 

medium-grained, with subround grains showing some 

secondary growth .........

Dolomite, brown, finely 

crystalline ...............

Dolomite, brown, sandy

Dolomite, brown, finely 

granular .................

Depth 

(feet)

700-705

705-712 

712-717

717-718

718-720 

720-732

732-736 

736-740

740-744 

744-746 

746-750 

750-758

758-760 

760-764 

764-770

770-776 

776-786

786-792

792-802 

802-806

806-818

818-820 

820-824

824-830 

830-837 

837-842

842-844

844-850 

850-855

855-860

15

Ordovician rocks Continued

Everton formation Continued

Depth 

(feet)

Dolomite, brown, finely 

granular, with pinpoint porosity ........... 860-866

Dolomite, very dark 

brown, resinous, very 

finely granular .......... 866-870

Dolomite, brown, sandy .... 870-875

Dolomite, brown, resinous,

very finely granular ...... 87S-880

Dolomite, brown, very 

fine, sandy, very finely 

granular ................ 880-885

Dolomite, brown, finely

crystalline .............. 885-890

Dolomite, buff, mediumcrystalline .............. §90-895

Dolomite, buff, mediumcrystalline, with thin 

layers of white finegrained sandstone ....... 895-900

Sandstone, white, finegrained ................. 900-901

Dolomite, buff, sandy ...... 901-907

Sandstone, white, finegrained ................. 907-908

Dolomite, buff to brown, 

finely to mediumcrystalline .............. 908-918

Sandstone, white, finegrained ................ 918-920

Dolomite, buff, finely

crystalline .............. 920-927

Dolomite, buff, with mediumsized subround sand 

grains included .......... 927-930

Dolomite, buff, sandy ...... 930-945

Dolomite, buff, finely 

granular to finely crystalline ................. 945-950

Dolomite, buff, finely crystalline ................. 950-960

Dolomite, buff, sandy ..... 960-970

Dolomite, buff, mediumcrystalline, sandy ....... 970-977

Dolomite, buff, fine, sandy . 977-980

Sandstone, white, finegrained ................. 980-981

Dolomite, buff, very finely

granular ................ 981-993

Sandstone, white, fineto medium-grained ...... 993-995

Sandstone, white, dolomitic,

fine- to medium-grained . 995-1^001

Limestone, buff, finely 

crystalline ............ 1, 001-1, 016

Limestone, white, sandy.. 1,016-1,020

Sandstone, white, slightly 

limy, fine- to 

medium-grained ....... 1, 020-1, 026

Limestone, buff, finely 

crystalline; contains 

tan oolites ............ 1, 026-1, 030

Dolomite, buff, mediumcrystalline ............ 1,030-1,033

Sandstone, white, fineto medium-grained .... 1,033-1,036
Ordovician rocks --Continued

Everton formation --Continued

Depth 

(feet)

Dolomite, buff, finely 

granular, slightly 

sandy................. I, 036-1,041

Sandstone, white, dolomitic, fine- to 

medium-grained ....... 1, 041-1, 045

Dolomite, buff, mediumcrystalline, with a 

thin seam of green 

shale ................. 1, 045-1,050

Dolomite, buff, mediumcrystalline to 

coarsely crystalline.... 1, 050-1, 055

Dolomite, buff, finely

granular .............. 1,055-1,060

Dolomite, buff, finely 

crystalline to finely 

granular .............. 1,060-1, 067

Sandstone, white, fineto medium-grained .... 1,067-1,076

Dolomite, buff-brown,

very sandy ............ 1, 076-1, 080

Dolomite, brown, very

finely granular......... 1, 080-1, 085

Dolomite, brown, very 

finely granular, with 

white siliceous 

oolites and sandstone 

grains cemented in 

white silica ........... 1, 085-1, 090

Sandstone, white, siliceous ................. 1, 090-1, 094

Dolomite, buff, sandy.... 1,094-1,099

Shale, dark-green ....... 1, 099-1,100

Dolomite, buff-brown,

very finely granular .... 1,100-1, 103

Shale, gray, dolomitic ... 1,103-1,104

Dolomite, buff-brown, 

very finely granular; 

c ale it e crystals ....... 1,104-1,115

Dolomite, very dark

brown to black, silty ... 1,115-1,120

Dolomite, buff to brown,

very finely granular .... 1,120-1,125

Dolomite, buff, very

finely granular ........ 1,125-1,130

Dolomite, buff, mediumcrystalline to coarsely 

crystalline, with included 

subround sand grains... 1,130-1,135

Dolomite, buff, finely 

crystalline, with 

included sand grains.... 1, 135-1,140

Dolomite, buff, finely

crystalline ............ 1, 140-1, 145

Dolomite, buff, finely 

crystalline; graywhite chert ........... 1,145-1,150

Dolomite, buff, mediumcrystalline, sandy ..... 1,150-1, 155

Dolomite, buff, finely 

crystalline; some 

sandy dolomite ........ 1, 155-1,163

Dolomite, creamcolored, very finely 

granular .............. 1,163-1,165

16

Ordovician rocks --Continued

Everton formation Continued

Depth 

(feet)

Dolomite, creamcolored, very finely 

granular, with 

scattered fine sand 

grains ................ 1,165-1,185

Powell(?) limestone:

Shale, gray-black........ 1, 185-1,187

Dolomite, creamcolored, very finely 

granular .............. 1,187-1,192

Shale, gray-black ....... 1,192-1,194

Dolomite, creamcolored, very finely 

granular .............. 1,194-1,197

Like overlying beds but 

with gray-black shale 

partings and green 

shale partings ......... 1,197-1,199

Dolomite, creamcolored, very finely 

granular .............. 1,199-1,219

Shale, green, waxy ...... 1,219-1,220

Dolomite, buff, finely 

granular; some black 

shale seams .......... 1, 220-1, 224

Shale, black............. 1,224-1,226

Dolomite, gray, finely 

granular; some included 

sand grains ........... 1, 226-1, 229

Shale, black............. 1,229-1,230

Dolomite, gray, finely 

granular; some included 

sand grains ........... 1, 230-1, 243

Shale, gray-black, slightly

dolomitic ............. 1,243-1,250

Dolomite, buff to brown,

finely granular ........ 1, 250-1, 256

Shale, gray-black ........ 1, 256-1, 257

Dolomite, buff, mediumcrystalline; creamcolored very finely 

granular dolomite ...... 1, 257-1, 262

Shale, dark-brown to.

black ................. 1,262-1,264

Dolomite, gray to buff,

finely granular ........ 1,264-1,275

Shale, dark-brown to

black ................ 1,275-1,277

Dolomite, buff, very

finely granular ........ 1, 277-1, 280

Dolomite, buff, mediumto coarsely crystalline . 1, 280-1,284

Dolomite, creamcolored, granular ..... 1,284-1,296

Shale, dark-brown to

black ................. 1,296-1, 298

Dolomite, creamcolored, granular...... 1,298-1,306

Shale, dark-brown to

black ................. 1,306-1, 308

Dolomite, creamcolored, granular...... 1,308-1,313

Shale, dark-brown to

black ................. 1,313-1, 315
Ordovician rocks --Continued

Powell(?) limestone --Continued

Dolomite, creamcolored, finely crystalline ...............

Dolomite, creamcolored, finely 

granular .............

Dolomite, creamcolored, finely 

granular; gray-buff 

dense chert ..........

Dolomite, buff, finely 

crystalline ...........

Dolomite, buff, finely 

crystalline; gray dense 

chert; white dense 

chert ................

Dolomite, gray-buff, 

finely crystalline .....

Shale, blue-green.......

Dolomite, brown,

finely crystalline .....

Dolomite, buff, finely 

crystalline; thin seams 

of light-green shale ...

Dolomite, buff, finely 

granular'.............

Dolomite, buff, granular

Dolomite, buff, mediumcrystalline; pyrite .-. 4 .

Dolomite, buff, finely 

to medium-crystalline; 

tan and brown banded 

dense chert ..........

Dolomite, cream- __ 

colored, very finely 

granular .............

Dolomite, gray, silty ...

Cotter(?) dolomite:

Dolomite, dark-buff, 

finely crystalline .....

Dolomite, dark-buff, 

finely crystalline; 

brown dolomite 

rhombs in white silica; much jvhite dense 

chert; gray and white 

banded chert .........

Dolomite, buff, finely 

crystalline; dolomite 

rhombs in- silica; 

calcite crystals ......

Dolomite, buff, finely 

crystalline; tan-gray 

dense chert ..........

Dolomite, gray-buff, 

finely crystalline .....

Dolomite, buff to brown, 

finely crystalline to 

dense; white dense 

chert................

Dolomite, gray-buff, 

very finely granular

Depth 

(feet)

1,315-1,320 

1,320-1,325

1,325-1,330 

1,330-1,335

1,335-1,340

1,340-1,342 

1,342-1,344

1,344-1,350

1,350-1,360

1,360-1,365 

1,365-1,370

1,370-1,374 

1,374-1,380

1,380-1,390 

1,390-1,400

1,400-1,405

1,405-1,410

1,410-1,420

1,420-1,426 

1,426-1,430

1,430-1,440 

1,440-1,450

Ordovician rocks Continued

Cotter (?) dolomite --Continued

Dolomite, gray-buff, 

very finely granular; 

white dense chert ......

Dolomite, buff, finely 

crystalline ............

Dolomite, buff, mediumcrystalline to coarsely 

crystalline; dolomite 

rhombs in white silica.,

Dolomite, buff, mediumcrystalline to coarsely 

crystalline; much 

white silica with dolomite rhombs; green 

shale fragments; white 

to tan dense chert

Dolomite, buff, finely 

crystalline; dull-white 

chert .................

Dolomite, brown, finely 

crystalline; white to 

milky dense chert

Dolomite, buff, finely 

crystalline ............

Dolomite, creamcolored, finely granular ...................

Dolomite, buff, finely 

crystalline ............

Dolomite, buff, finely 

crystalline; gray chert , Dolomite, buff, finely 

crystalline; buff 

coarsely crystalline 

dolomite; dolomite 

rhombs in white 

silica; banded white 

and gray chert; white 

finely oolitic chert

Dolomite, buff, finely 

crystalline ............

Dolomite, buff, finely 

crystalline; trace of 

white dense chert ......

Dolomite, buff, finely 

crystalline; smokygray chert ............

Dolomite, creamcolored, medium- to 

coarsely crystalline

Dolomite, gray-buff, 

finely crystalline

Dolomite, creamcolored, finely to 

medium-crystalline

Dolomite, creamcolored, finely 

granular .............

Dolomite, buff, finely 

granular .............

Dolomite, buff, finely 

crystalline; white 

dense chert; blackspeckled gray chert

Depth 

(feet)

1,450-1,455 

1,455-1,460

1,460-1,465

1,465-1,470 

1,470-1,475

1,475-1,480 

1,480-1,490

1,490-1,495 

1,495-1,510 

1,510-1,518

1,518-1,525 

1,525-1,530

1,530-1,535 

1,535-1,540

1,540-1,544 

1,544-1,550

1,550-1,560

1,560-1,565 

1,565-1,570

1,570-1,575

17
Ordovician rocks --Continued

Cotter (?) dolomite --Continued

Dolomite, buff, finely to 

medium-crystalline; 

white dense chert ......

Dolomite, buff, mediumcrystalline to coarsely 

crystalline ............

Dolomite, buff, finely 

crystalline; white dense 

chert with included 

dolomite rhombs.......

Dolomite, buff, finely 

crystalline; white dense 

chert; calcite crystals .

Dolomite, buff, mediumcrystalline to coarsely 

crystalline; white dense 

chert .................

Dolomite, buff, finely 

crystalline ............

Dolomite, buff, very 

finely granular ........

Dolomite, creamcolored, finely granular; 

trace of white dense 

chert .................

Dolomite, buff, finely 

crystalline; white dense 

chert; pyrite; milky 

chert .................

Dolomite, buff, finely 

granular to finely crystalline ..............

Dolomite, buff, finely 

granular to finely crystalline; black-speckled, 

light-gray dense chert..

Dolomite, creamcolored, very finely 

granular; trace of sandy 

chert ..................

Dolomite, creamcolored, very finely 

granular ...............

Dolomite, brown, finely 

crystalline; much 

white porcelainlike 

chert with brown dolomite rhombs included; 

gray dense chert with 

white speckles.........

Dolomite, buff, finely 

crystalline, with few 

scattered subround 

sand grains ...........

Dolomite, buff, mediumcrystalline to coarsely 

crystalline; much 

white porcelainlike 

chert with included 

dolomite rhombs ......

Dolomite, buff, finely 

crystalline, white 

pyritic chert ..........

Dolomite, brown, finely 

crystalline; white 

dense chert ...........

Depth 

(feet)

1,575-1,580 

1,580-1,585

1,585-1,590 

1,590-1,595

1,595-1,600 

1,600-1,610 

1,610-1,615

1,615-1,620

1,620-1,627 

1,627-1,635

1,635-1,640

1,640-1,645 

1,645-1,650

1,650-1,660 

1,660-1,670

1,670-1,675 

1,675-1,680 

1,680-1,685

Ordovician rocks --Continued

Cotter (?) dolomite --Continued

Depth 

(feet)

Dolomite, creamcolored, very finely 

granular .............. 1,685-1, 697

Dolomite, brown, finely

crystalline ............ 1, 697-1, 700

Dolomite, gray-buff, finely

granular .............. 1,700-1, 705

Dolomite, buff, coarsely

crystalline ............ 1, 705-1, 710

Dolomite, buff, finely

to medium-crystalline. . 1,710-1,720

Dolomite/ creamcolored, finely granular; white dense chert; 

pyrite ................ 1,720-1,730

Dolomite, creamcolored, finely granular ................... 1,730-1,734

Dolomite, dark-buff, 

finely crystalline; 

white- and creambanded pyritic chert ... 1, 734-1, 740

Dolomite, buff, finely

crystalline; pyrite ..... 1, 740-1, 744

Dolomite, buff, finely 

crystalline; brown 

dense chert ........... 1, 744-1,750

Jefferson City(?) dolomite:

Dolomite, gray-buff, 

finely granular; brown 

dense chert ........... 1, 750-1,756

Dolomite, dark-buff, 

finely crystalline; 

brown chert with 

white spots ........... 1,756-1,760

Dolomite, buff, sandy,

finely granular ........ 1, 760-1, 770

Dolomite, brown, mediumcrystalline, with calcite and dolomite 

rhombs in white 

silica; trace of tan 

oolitic chert .......... 1, 770-1, 780

Dolomite, buff, finely 

granular; white dense 

chert; tan translucent 

chert containing 

Archeosoyphia? ....... 1,780-1,785

Dolomite, buff, finely 

granular; white dense 

chert with fine black 

specks ............... 1, 785-1, 790

Dolomite, creamcolored, very finely 

granular .............. 1,790-1, 795

Dolomite, creamcolored, mediumcrystalline to 

coarsely crystalline; 

white interstitial 

silica; white figured 

chert ................. 1, 795-1, 800

18
Ordovician rocks Continued

Jefferson City(?) dolomite Continued

Depth 

(feet)

Dolomite, buff, finely 

granular; white subtranslucent figured 

chert; white subtranslucent oolitic chert..... 1, 800-1,805

Dolomite, buff, finely 

granular; white dense 

chert ................. 1, 805-1, 810

Dolomite, buff, mediumcrystalline; dolomite 

rhombs in white silica; 

white dense chert ...... 1, 810-1, 815

Dolomite, gray-buff, 

finely to mediumcrystalline; glauconite . 1,815-1,820

Dolomite, gray-buff, 

finely crystalline; 

white subtranslucent 

oolitic and sandy 

chert ................. 1,820-1,825

Dolomite, creamcolored, mediumcrystalline to coarsely 

crystalline; white 

subtranslucent oolitic 

and sandy chert........ 1,825-1, 830

Dolomite, gray-buff, 

finely granular;-white 

dense chert ........... 1, 830-1, 835

Dolomite, white, coarsely

crystalline ............ 1, 835-1, 840

Dolomite, buff, finely

crystalline ............ 1, 840-1, 845

Dolomite, buff, finely 

crystalline; white 

dense chert; white 

subtranslucent 

chert .................. 1,845-1,850

Dolomite, dark-buff,

finely crystalline ...... 1,850-1,860

Dolomite, gray-white, 

finely granular; slightly 

sandy, in part ......... 1,860-1, 865

Dolomite, dark-buff,

finely crystalline ...... 1, 865-1, 870

Dolomite, creamcolored, finely 

granular .............. 1,870-1,885

Dolomite, brown, finely

crystalline ............ 1, 885-1, 890

Dolomite, brown, finely 

crystalline; brown 

dense chert containing 

scattered sand grains .. 1, 890-1, 895

Dolomite, creamcolored, very finely 

granular .............. 1,895-1,900

Dolomite, dark-brown, 

resinous, finely 

granular ............. 1,900-1,910

Dolomite, gray-green, 

with included sand 

grains ................ 1,910-1,915

Dolomite, buff, granular ................... 1,915-1,920

Ordovician rocks Continued

Jefferson City(?) dolomite Continued

Depth 

(feet)

Dolomite, gray, very

finely granular ........ 1,920-1,925

Dolomite, brown, finely

crystalline ............ 1, 925-1, 930

Dolomite, buff, finely

granular ............. 1,930-1,945

Dolomite, gray, slightly

silty ................. 1,945-1,950

Dolomite, creamcolored, finely granular; gray-white 

slightly figured chert... 1, 950-1, 960

Dolomite, creamcolored, finely 

granular, with included sand grains ..... 1, 960-1, 965

Dolomite, brown, finely

crystalline ............ 1, 965-1, 970

Dolomite,. brown, finely

granular .............. 1,970-1,974

Dolomite, creamcolored, sandy, very 

finely granular; white 

very sandy chert ...... 1,974-1,980

Dolomite, creamcolored, very finely 

granular .............. 1,980-1,987

Dolomite, gray-white, finely

to medium-crystalline .. 1, 987-2,000

Dolomite, creamcolored, finely 

granular .............. 2,000-2,005

Dolomite, gray-buff,

finely crystalline ...... 2,005-2,010

Dolomite, gray-buff, 

finely crystalline; white 

dense chert ........... 2,010-2,020

Dolomite, buff, coarsely 

crystalline, trace of tan 

translucent chert ...... 2,020-2,030

Limestone, dark-buff, 

finely crystalline, 

dolomitic ............. 2,030-2,033

Limestone, dark-buff .... 2,033-2,040

Limestone, light-buff, 

finely crystalline; tan 

subtranslucent chert; 

smoky chert........... 2, 040-2, 060

Limestone, light-buff, 

finely crystalline ...... 2,060-2,075

Limestone, creamcolored, finely crystalline; white dense chert; 

tan slightly figured 

subtranslucent chert ... 2,075-2,080

Limestone, creamcolored, finely crystalline; chert not so 

abundant .............. 2,080-2,086

Dolomite, creamcolored, finely 

granular .............. 2,086-2,090

Dolomite, creamcolored, fine, sandy ... 2,090-2,096

19
Ordovician rocks Continued « 

Jefferson City(?) dolomite Continued

Depth 

(feet)

Limestone, buff, finely 

crystalline to dense; 

white subtranslucent 

chert ................. 2,096-2,100

.Roubidoux( ?) formation:

Limestone, buff, finely 

crystalline, faintly 

oolitic ................ 2,100-2, 105

Limestone, buff, finely 

crystalline; gray subtranslucent chert ...... 2,105-2,110

Limestone, dark-buff, 

finely crystalline to 

dense ................ 2,110-2,130

Limestone, buff, sandy, 

with some white dolomitic and siliceous 

oolites ............... 2,130-2, 134

Sandstone, white, limy,

fine-grained .......... 2,134-2,137

Dolomite, gray, sandy; 

white subtranslucent 

sandy chert ........... 2, 137-2, 142

Limestone, creamcolored, finely 

crystalline to dense .... 2,142-2,150

Limestone, creamcolored, finely 

crystalline to dense; 

tan to smoky-gray 

dense chert ........... 2,150-2,170

Dolomite, gray-buff,

finely granular; tan ,

to smoky-gray dense

chert ................. 2, 170-2, 172

Sandstone, gray, quartzitic ................. 2,172-2, 178

Sandstone, white, dolomitic, fine-grained .... 2, 178-2,180

Limestone, creamcolored, finely 

crystalline to dense; 

tan to gray subtranslucent chert ........... 2,180-2, 187

Sandstone, white, dolomitic, fine- to 

medium-grained ....... 2,187-2,190

Sandstone, white, limy,

fine- to medium-grained 2, 190-2,192

Limestone, creamcolored, fine, sandy ... 2,192-2,200

Limestone, creamcolored, fine, sandy; 

tan translucent chert ... 2, 200-2, 204

Limestone, buff, finely

crystalline to dense .... 2, 204-2, 210

Dolomite, white, finely 

crystalline, with 

included round sand 

grains ............... 2,210-2,215

Dolomite, white, finely

crystalline ............ 2, 215-2, 220

Dolomite, buff, coarsely

crystalline ............ 2, 220-2, 230

20

Ordovician rocks --Continued

Roubidoux(?) formation --Continued

Depth 

(feet)

Dolomite, buff, coarsely 

crystalline; light-buff 

oolitic chert........... 2, 230-2, 240

Limestone, buff, finely

crystalline to dense ... 2, 240-2,255

Limestone, buff, finely 

crystalline to dense; 

gray-black dense 

chert ................. 2,255-2,260

Limestone, buff, finely

crystalline to dense .... 2, 260-2, 267

Dolomite, white, sandy,

or limestone .......... 2, 267-2, 270

Limestone, buff, finely 

crystalline to dense; 

light-buff sandy chert; 

gray translucent chert.. 2, 270-2, 275

Limestone, buff, finely 

crystalline to dense; 

gray-black dense 

chert ................. 2, 275-2, 290

Limestone, creamcolored, finely 

crystalline to dense .... 2, 290-2, 300

Limestone, creamcolored, finely 

crystalline to dense; 

tan figured chert ...... 2, 300-2, 306

Dolomite, gray-buff, 

coarsely crystalline; 

white dense chert; tan 

subtranslucent chert.... 2, 306-2, 310

Dolomite, creamcolored, very finely 

granular; white to lightbuff subtranslucent 

chert ................. 2, 310-2, 320

Dolomite,, buff, finely 

granular; quartz crystals ................. 2,320-2, 325

Dolomite, gray-buff, 

finely granular to 

finely crystalline; 

blue chert with gray 

speckles .............. 2,325-2, 330

Dolomite, buff, finely 

crystalline to finely 

granular; white dense 

chert containing dolomite rhombs .......... 2, 330-2, 336

Dolomite, buff, sandy .... 2, 336-2, 340

Dolomite, creamcolored, finely crystalline; white sandy 

chert ................. 2,340-2, 345

Dolomite, creamcolored, finely crystalline .................. 2,345-2,350

Dolomite, white, sandy, 

granular; trace of 

white and gray chert ... 2, 350-2, 355

Dolomite, white, sandy... 2, 355-2, 360

Sandstone, white, dolomitic, fine- to mediumgrained, with subround 

to subangular grains ... 2^360-2, 366
Ordovician rocks Continued

Gasconade(?) dolomite:

Depth 

(feet)

Dolomite, creamcolored, mediumcrystalline ............ 2,366-2, 375

Dolomite, creamcolored, finely granular; dull-white pyritic 

chert................. 2,375-2, 380

Dolomite, gray, finely

granular .............. 2,380-2, 385

Dolomite, creamcolored, finely crystalline ............... 2, 385-2, 390

Dolomite, creamcolored, mediumcrystalline ............ 2,390-2, 395

Ordovician rocks Continued

Gasconade(?) dolomite --Continued

Depth 

(feet)

Dolomite, creamcolored, mediumcrystalline; blue-gray 

chert; translucent 

sandy chert ............. 2,395-2,400

Dolomite, creamcolored, coarsely 

crystalline .............. 2, 400-2, 405

Dolomite, creamcolored, coarsely 

crystalline; white 

dolomite rhombs ......... 2, 405-2,410

Dolomite, creamcolored, coarsely 

crystalline .............. 2,410-2, 415

Total depth 2,415

21 INT.-OOP. SEC., WASH.. D.C.19«J»