Stratigraphic and Mineralogic 

Relations and Ceramic Properties of 

Clay Deposits of Eocene Age in the 

Jackson Purchase Region, Kentucky 

and in Adjacent Parts of Tennessee 

By WILDS W. OLIVE and WARREN I. FINCH 

GEOLOGICAL SURVEY BULLETIN 1282 

Prepared in cooperation with the 

Kentucky Geological Survey 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969 
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HICKEL, Secretary 

GEOLOGICAL SURVEY 

William T. Pecora, Director 

Library of Congress catalog-cam No,. GS 68-366 

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

Washin~ton, D.C. 20402 - Price 25 cents (paper cover) 
CONTENTS 

Page 

Abstract---------------------------------------------------------- 1 

Introduction______________________________________________________ 1 

Purpose of report and methods of sampling_______________________ 3 

Acknowledgments_____________________________________________ 3 

Previous work_________________________________________________ 3 

Structure_________________________________________________________ 4 

General stratigraphy_______________________________________________ 4 

Wilcox Formation ____________________________________ ·_________ 7 

Claiborne Formation _______________________ ~___________________ 7 

Jackson Formation____________________________________________ 10 

Economic geology_____________________________________ _ _ _ _ _ _ _ _ _ _ _ _ 11 

History of clay production______________________________________ 11 

General description of developed clay deposits in the Claiborne 

Formation__________________________________________________ 14 

Origin of clay deposits_________________________________________ 14 

~ineralogy___________________________________________________ 16 

Types of clay_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 21 

Relations between type and mineralogy__________________________ 22 

Description, ceramic properties, and potential use of undeveloped clay 

deposits-------------------------------------------------------- 24 

Summary and conclusions__________________________________________ 32 

References cited___________________________________________________ 34 

ILLUSTRATIONS 

Page 

FIGURE 1. Geologic map of the Jackson Purchase region, Kentucky, showing fossil localities_____________________________________ 9 

2. ~ap of the Jackson Purchase region, Kentucky, and adjacent 

parts of Tennessee, showing location of samples and clay 

pits__________________________________________________ 13 

3. Composition diagram of clay minerals from Eocene clay deposits________________________________________________ 33 

III 
IV CONTENTS 

TABLES 

Page 

TABLE 1. Generalized section of stratigraphic units of Late Cretaceous 

to Holocene age in the Jackson Purchase region___________ 5 

2. Ball-clay production from the Jackson Purchase region, Kentucky, 1900-60---------------------------------------- 11 

3. Description and X-ray mineralogic analyses of clay samples 

from the Jackson, Claiborne, and Wilcox Formations_ _ _ _ _ _ 17 

4. Size analyses of whole-rock samples from the Jackson, Claiborne, and Wilcox Formations__________________________ 20 

5. Range in percent of kaolinite, mica, and quartz in clays used 

in British fine ceramics industries------------------------ 23 

6. Calculated kaolinite, other clay minerals, and quartz content of 

clay samples from the Jackson, Claiborne, and Wilcox Formations______________________________________________ 24 
STRATIGRAPHIC AND MINERALOGIC RELATIONS AND 

CERAMIC PROPERTIES OF CLAY DEPOSITS OF EOCENE 

AGE IN THE JACKSON PURCHASE REGION, KENTUCKY, 

AND IN ADJACENT PARTS OF TENNESSEE 

BY WILDS W. OLIVE and WARREN I. FINCH 

ABSTRACT 

Clay deposits in the Jackson Purchase region, Kentucky, and in adjacent 

parts of Tennessee, in the northeastern part of the Mississippi embayment, are the 

major domestic source of ball clay. The deposits are widely spaced lenses in the 

Wilcox, Claiborne, and Jackson Formations of Eocene age. All deposits mined, 

except one in the Wilcox, are in the Claiborne. 

X~ray analyses of clay from deposits in each of the three formations show that 

clay-mineral composition varies according to stratigraphic position. The clay 

deposits in all formations are chiefly kaolinite, but montmorillonite, illite, and 

mixed-layer clay are present. Kaolinite is considerably more abundant in ,the 

Wilcox and Claiborne Formations; it averages 70 percent of the total clay in 16 

samples analyzed. Montmorillonite, which rarely exceeds 5 percent in Wilcox 

and Claiborne clay deposits, generally makes up a large part, 14 to 50 percent, in 

most samples from clay deposits in the Jackson Formation. Clay that contains 

more than 10 percent montmorillonite is unsuited for most ceramic purposes. 

Thus, X-ray data indicate that the Claiborne and Wilcox Formations have greater 

potential as sources of ceramic-grade clay than has the Jackson Formation. 

Most commercial clay deposits in Kentucky are in lenses in strata indicated by 

pollen to be of middle and late Claiborne age. The pollen types and lithologic 

relations suggest that these clay lenses were deposited in two ancient valleys. 

Mineralogic and ceramic analyses of several undeveloped clay deposits in the 

Claiborne and Wilcox Formations indicate that they have potential value for use 

in ceramics. 

INTRODUCTION 

The clay deposits of Eocene age in the Jackson Purchase region J. 

of Kentucky 'and in ~adjacent parts of Tennessee, in the nortJheastern 

part of the Mississippi embayment, are the major source of ball day in 

the United States. Much information was gathered on the occurrence, 

1 Parts of Kentucky and Tennessee west of the Tennessee River were acquired from the 

Chickasaw Indians by treaty signed in 1818. General Andrew Jackson, who represented 

the United 'States, was placed in a position of having to conclude the treaty in his own 

name. Subsequently, the Kentucky part O!f the area covered by the treaty came to be known 

as the Jackso'n Purchase region; and the Tennessee part, as West Ten,nessee. 

1 
2 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

mineralogy, and ceramic qualities of the clays during investigations 

that were part of the cooperative geologic mapping program of 

Kentucky by the l{entucky Geological Survey and the U.S. Geological 

Survey. 

The area in this report is a gently to moderately rolling plain traversed by broad, flat, north- to west-trending valleys. At places the 

valleys are bordered by areas of rugged relief and steep slopes. Local 

relief is generally less than 75 feet; however, along bluffs bordering 

the Mississippi River valley south of Wickliffe, local relief is more 

than 125 feet at many places and is as much as 200 feet. at Chalk Bluffs, 

about 3 miles south of Columbus. 

The youngest sediments, other than alluvium, in the region consist of 

continental gravel deposits of Pl,iocene(?) and Pleist~ocene age and 

loess of Pleistocene age. The gravel deposits form an extensive blanket 

that overlies Eocene rocks in upland areas, attains a maximum thickness of as much as 100 feet in the southeastern part of the region, and 

thins to less than 30 feet in the northern part. The gravel deposits are 

thin to loeally absent in the western part. Loess, consisting predominantly of silt of late Pleistocene age, forms a blanket that conceals all 

older sediments throughout much of the region. In upland areas bordering the Mississippi River valley, the loess reaches a maximum thickness 

of more than 80 feet; here, it overlies the continental gravel deposits or 

rests directly on Eocene sediments. The loess thins eastward and is 8 

to 12 foot thick near the eastern edge of the area, where it generally 

rests on the gravel deposits and, rarely, on older sediments. In valley 

bottoms the Eocene sediments are generally concealed by alluvium of 

Pleistocene and Holocene age. The alluvium ranges in thickness from 

a few feet in the smaller valleys to as much as 200 feet in the Ohio and 

MissiRSi ppi River valleys. 

Exposures of Eocene sediments are patchy and discontinuous. The 

best outcrops are in highway and railroad cuts and in deep, narrow 

channels of small high-gradient streams where erosion has incised 

through thin alluvium. Exposures also occur on the lower parts of 

steep slopes but are not common because they are concealed by accumulations of colluvium that may be 5 or more feet thick. Rarely are more 

than 15 feet of Eocene sediments exposed in one locality. Outcrops in 

the eastern part of the area are fairly numerous and closely spaced; 

whereas, in the western and southwestern parts ;t.hey are sparse and 

widely spaced, except along the Mississippi River bluffs where they 

are continuous for long distances. In areas of poor exposure, informa.-

tion on the lithology of the Eocene sequence is hased largely on a study 

of samples from drill holes, which are generally spaced a mile or 

more apart. 
IN1'RODUCTION 3 

PURPOSE OF REPORT AND METHODS OF SAlYIPLING 

This report presents evidence which indicates that the mineralogic 

composition of clay deposits of Eocene age in the Jackson Purchase 

region of Kentucky and in adjacent parts of Tennessee varies according 

to stratigraphic position. Mineralogic composition of samples from 

undeveloped clay deposits is compared with that of samples from 

developed deposits. Based in part on the comparison of mineralogy 

and in part on data from ceramic tests, the potential use or type of 

clay is indicated. 

The evidence presented is based primarily on results of investigations 

of 34 samples, most of which were taken from outcrops, but a few were 

obtained by augering. Those from ourtcrops are grab samples taken 

from freshly cleaned exposures. Three clay bodies were sampled by 

augering with a truck-mounted, 4lj2-inch-diameter auger, and one 

sample was collected with a 1 %-inch hand auger. All augered samples 

are from depths of 105 feet or less. Only one sample was taken from 

most clay bodies; hence, results of X-ray diffraction and ceramic 

analyses reported for individual samples do nort necessarily represent 

the entire composition or ceramic characteristics of a large clay body. 

ACKNOWLEDGMENTS 

The analytical work for this report was done by others. R. P. 

Christian and H. A. Tourtelot, both of the U.S. Geological Survey, 

supplied X-ray diffraction and size analyses of clay samples, and 

R. H. Tschudy (1965a, 1965b, 1966, 1967) provided palynologic data 

that facilitated stratigraphic correlations. The writers are grateful to 

the managements of The Kentucky-Tennessee Clay Co. and The Old 

Hickory Clay Co. for their permission rto publish data on samples of 

commercial-grade clay obtained from their mines in Kentucky and 

Tennessee. Data on ceramic tests of samples from undeveloped clay 

deposits were provided by M. V. Denny and M. E. Tyrell of the U.S. 

Bureau of Mines. 

PREVIOUS WORK 

Loughridge (1888, p. 84-118) was one of ~the first to discuss the 

economic potentialities of clay deposits in the area. He described numerous clay deposits and presented several chemical analyses andresults of ceramic tests. Chemical and ceramic data for many deposits 

were included in a report by Easton (1913). The history and methods 

of clay mining in the J·ackson Purchase region of Kentucky were 

discussed by Gildersleeve ( 1945), who also described strll!tigraphic 

sections from several pits and presented chemical and ceramic data 

on different types of clay mined in. the a.rea. Whitlll!tch ( 1940) reported 

on the clay industry in West Tennessee and described numerous 
4 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

undeveloped clay deposits. Data on ceramic tests of samples from clay 

exposed at many locaHties in the Jackson Purchase region of Kentucky 

are in several publications by the Kentucky State Geological Survey 

(Floyd and Kendall, 1955; McGrain and Kendall, 1957; McGrain and 

others, 1960; Walker, 1953). 

Pryor and Glass (1961), in a report on the mineralogy of Cretaceous 

and Tertiary elay deposits from the upper Mississippi embayment, 

listed data from X-ray analyses of samples from Eocene clay deposits. 

As indicated by their index map (Pryor and Glass, 1961, p. 40) and 

by location descriptions (Pryor, written commun., 1966), all Eocene 

samples used in their study are from the lower and middle parts of 

the Eocene sequenee. Merschat and Larson (1967) reported that X-ray 

and thermal analyses of more than 60 samples from Eocene clay deposits in West Tennessee, ineluding that part of Tennessee in figure 2, 

show that rthe deposits are eomposed dominantly of kaolinite and 

quartz. 

STRUCTURE 

Eocene formations exposed in the region strike parallel rto the periphery of the Mississippi embayment and dip west to south toward 

the embayment axis, which roughly coincides with the east valley wall 

of the Mississippi River valley. Owing to a lack of key horizons and 

to general concealment, the angle of dip of the strata can only be 

approximated. Correlation of surface and subsurface data indicates 

that the regional dip of the unconformity at the base of the Eocene 

series is westward and southward at slightly more than 30 feet per 

mile. Locally, exposed Eocene strata have high-angle dips in directions 

acutely variant from the regional dip; however, outcrops rarely afford 

sufficient information on the cause of these erratic attitudes. Many may 

be caused by slumping shor~tly after deposition; others may be due to 

faulting, which can ~ demonstrated with certainty at very few 

localities. 

GENERAL STRATIGRAPHY 

Eocene strata of the Jackson Purchase region of Kentucky and 

adjoining areas of Tennessee are part of a thick sequence of sediments 

that range in age from Upper Cretaceous to Holocene. A generalized 

description of the sequence is presented in table 1. The Eocene section 

is composed largely of sand, clayey sand, silt, and clay; it attains a 

maximum thickness of about 1,350 feet at the southern edge of the area 

along the Mississippi embayment axis. Fossil palynomorphs, including 

pollen, dinoflagellates, and hystrichospheres, from beds at irregular 

intervals throughout the Eocene section indicate that the sediments 
GENERAl. STRATIGRAPHY 5 

were deposited in fresh-water and near-shore marine environments 

(R. H. Tschudy, oral commun., 1967). Eocene sediments unconformably overlie the Porters Creek Clay of Paleocene age which is composed 

of montmorillonitic clay and glauconitic sand. 

TABLE 1. -Generalized section of stratigraphic units of Late Cretaceous to Holocene 

age in the Jackson Purchase region 

System Series Formation Thickness 

(feet) 

Character 

--------~l------------l---------1------------------------------------ <l) ~ 

2'0 ~ 8>==-8 0 ~.~ 

p:: ~ 

Alluvium 

and 

lacustrine 

deposits 

Loess 

Continental 

deposits 

Jackson 

Formation 

Claiborne 

Formation 

Wilcox 

Formation 

326-945 0--69--2 

0-185 

Q-80 

Q-100 

Brown to gray silt, sand, and gravel; 

rarely calcareous. Thickest beneath 

flood plains of Mississippi, Ohio, and 

Tennessee Rivers. 

Brown to gray silt, intermixed with 

minor amounts of clay and fine sand; 

nonstratified blanketlike deposit; 

locally calcareous and fossiliferous. 

Thickest near Mississippi River; thins 

eastward. 

Brown to reddish-brown gravel; pebbles 

dominantly chert and subordinately 

quartz; scattered lenses of clay and 

sand; contains fairly continuous middle 

member composed of sand and clay 

in south-central part of region. Thins 

northward and westward. 

400± Brown to gray silt and clay with thin 

beds and lenses of light-colored quartz 

sand; cross bedded in part; very sparse 

clay-ball sand; locally abundant car- bonized plant remains; probably intergrades with Claiborne. May include 

beds of Oligocene age in upper 100 ft 

of sequence. Thickens toward axis of 

Mississippi embayment. 

500± Light-colored quartz sand with thin 

lenses of dominantly gray silt and 

clay; commonly cross bedded; numerous clay-ball sand beds; carbonized plant 

remains common in clay; locally con- tains thin lignite beds. Overlies Wilcox 

Formation unconformably in most of 

area; overlaps Wilcox in east-central 

part of area and lies unconformably on Porters Creek Clay. 

350 ± Light-colored clayey quartz sand and 

sandy clay commonly referred to as "sawdust sand" which is characterized 

by white kaolinite clay grains and 

minute striate rods; thin beds and 

lenses of clay and cross bedded sand; 

basal coarse sand common. Unconformably overlies Porters Creek Clay. 
6 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

TABLE 1.-Generalized section of stratigraphic units of Late Cretaceous to Holocene 

age in the Jackson Purchase region-Continued 

System Series Formation I Thickness 

(feet) 

Character 

------1-------------1------------------

Porters 

Creek Clay 

200 Light- to dark-gray montmorillonitic clay, 

locally glauconitic; beds of gray 

to brown micaceous and generally 

glauconitic sand common in lower and 

upper parts; intersected at many 

places by vertical to near vertical 

clastic dikes. Overlies Clayton and 

McNairy Formations, conformably in 

most places. 

Clayton and 125-275 

McNairy 

Formations 

Gray to brown interlensing sand and 

clay, characterized by thin laminae, 

blebs, and minute lenses of white 

clean very fine micaceous quartz sand. 

Lower part dominantly light-gray to 

brown crossbedded quartz sand; car- bonized plant remains and iron-sulfide 

nodules common; sparse scattered 

lenses of chert-pebble and quartzsand-matrix gravel in lower 50 ft. 

Overlies unconformable Tuscaloosa 

Formation and Paleozoic rocks. 

Tuscaloosa 

Formation 

0-165 Pale-gray to pale-orange-chert-pebble 

gravel in a chert-sand, silt, and clay 

matrix; contains irregularly spaced 

thin lenses of chert sand, silt, and clay. 

Formation occurs as scattered lenses 

in area bordering Kentucky Lake. 

Unconformably overlies Paleozoic limestone, chert, and shale. 

The Eocene sequence lacks marker beds, is devoid of fossil fauna, and 

is generally concealed by surficial deposits. Stratigraphic correlations 

are hased mainly on regional palynological studies. Stratigraphic and 

palynological investigations indicate that the Eocene sequence contains 

strata that are equivalent, at least in part, to the subsurface Wilcox, 

Claiborne, and Jaekson Groups of lower, middle, and upper Eocene 

ages, respectively. In outcrops of the Jackson Purchase region, none 

of these units can be subdivided, and they are therefore designated as 

formations. Figure 1 shows the distribution of the three formations in 

the Jackson Purchase region. Clay deposits in the upper 100 feet of 

the sequence eontain a pollen assemblage that indicates they may be 

Oligocene in age and partly equivalent to the Bucatunna Clay Member 

of the Byram Formation in Mississippi. For convenience of discussion 

these beds are included within the Jackson Formation. 
GENERAL STRATIGRAPHY 7 

WILCOX FORMATION 

The Wilcox Formation consists mainly of thinly laminated, poorly 

sorted, intermixed sand, clay, and silt. Because of poor sorting, the 

Wilcox in general has low permeability; however, in some areas clean, 

well-sorted, medium to coarse sand, as much as 40 feet thick, forms the 

basal part of the formation and occurs as widely spaced lenses within 

the less permeable sediments. Much sand of the Wilcox Formation is 

fine, very clayey, rnicaceous, and white specked; because of its appearance, it is comonly referred to as "sawdust sand" (Whitlatch, 1940, p. 

233). The "sawdust sand" and, at places, other sediments of the Wilcox 

commonly contain white, curved, striate rods with well-formed transverse cleavage. These rods are 2 to 3 mm (millimeters) long and have 

a length-width ratio of about 4:1. X-ray analysis (Finch, 1964; 

Charles Milton, written commun., 1963) shows that they are composed 

of kaolinite, as is most clay in "sawdust sand." The rods are similar in 

shape and composition to authigenic kaolinite crystals with vermicular 

·habit described by Ross and Kerr (1931, p. 161-163, 173, pis. 39, 41, 

43). Neither "sawdust sand" nor kaolinite rods, except broken pieces, 

have been observed in younger Eocene sediments. Lenses of clay-ball 

conglomerate and clay breccia, some with imbricate structure, are com4 

mon in the lower part of the Wilcox and are widely spaced higher in 

the formation. The Wilcox attains a. maximum thickness of about 250 

feet in the outcrop area and is as much as 335 feet thick near the embayment axis. 

Wilcox clay deposits contain varying amounts of silt and sand. The 

clay is light gray to black and various shades of brown, weathering 

dark yellowish brown to white and mottled pastel shades of red and 

orange. Muscovite is sparse to absent. Leaf imprints and comminuted 

lignitic material are rubundant at some horizons. The clay is thin bedded 

to massive and occurs as lenses a few to a thousand feet or more across 

and as much as 30 feet thick. Lenses of sandy pisolitic clay 3 to 4 inches 

thick occur near the base of the formation at several places in the eastern part of the ·area. 

The Wilcox Formation is overlain unconformably and, at places, is 

overlapped by the Claiborne Formation. In much of the outcrop area., 

Wilcox sediments filled stream valleys within the Porters Creek Clay. 

CLAIBORNE FORMATION 

The Claiborne Formation is composed of sand, clay, and lignite beds. 

Sand probably makes up more than 90 percent of the formation. The 

sand is eomposed of angular to well-rounded fine to medium and, at 

places, coarse to granular quartz, dark minerals, and, locally, muscovite. Crossbedding and cut-and-fill structures are common. Lenses of 
~\. 

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EXPLANATION 

Surficial deposits of Pliocene(?), Pleistocene, and Holocene age not shown 

~ ~-

~ 

r::::_->!::.:_::_::-J 

Jackson Formation 

May include some sedim~nts 

of Oligocene age 

0 

Claiborne Formation 

Wilcox ~ Formation 

Older 

~ rocks 

Includes Tcrtia·ry, Cretaceous, and 

Paleozoic formations, undifferentiated 

Contact 

>-

0::: 

<( 

i= 

0::: 

w 

...... 

<(0...0 ...... 

-a.. we::: 

z:~~~ 

Z-uw 0(/)c::e ...... >~ ...... W(J)Wo 

O(J)c:::z 

:iEUc::e 

Dashed where approximately located; short 

dashed where inferred. Concealed for most 

part by younger contiMntal deposits, loess 

and alluvium 

X C-2 G J-1 

Outcrop Drill hole 

Fossil locality 

Symbol refers to USGS paleobotanical locality number given below. J, 

sample of Jackson age; J-6 and J-7, may be of Oligocene age; C, 

Claiborne age; W, Wilcox age. Depth of drill-hole sam.ple, in feet, 

enclosed in parentheses. Palynomo·rphs identified by Tschudy 

(1965a,b, 1966, 1967) 

J-1, D3946(103) 

J-2, D4083(71) 

J-3, D3879(85) 

J-:4. 

J-5, 

J-6, 

J-7, 

J-8, 

J-9, 

J-10, 

J-11, 

J-12, 

J-13, 

J-14, 

J-15, 

J-16, 

J-17, 

J-18, 

J-19, 

D3880(42) 

D3881(69} 

D1891(120) 

D3005(65) 

D3006(60} 

D1898 

D3765 

D3763 

D3940{89) 

D3819(120) 

D3837(103) 

D3836(40) 

D3955(127) 

D3960(70) 

D3882(130) 

D3956(100) 

D3838(56) 

C-1, D3008(75) 

C-2, D3009(75) 

C-3, D3377 

C-4, D3193 

C-5, D3375 

C-6, D3040 

C-7, D3428C(43) 

C-8, D3457( 45) 

C-9, D3558 

C-10, D3339 

C-11, D3348 

C-12, D3332 

C-13, D3338 

C-14, D3680(88) 

C-15, D3958(66) 

C-16, D3528(26) 

C-17, D3521 

C-18, D3527(97) 

C-19, D1667 

C-20, D3884{56) 

C-21, D3888{100) 

C-22, D3821(165) 

W-1, D3762 

W-2, D3743 

W-3, D3767 

W-4, D351.5 

W-5, D3460(35) 

W-6, D3018 

W-7, D3954(55) 

W-8, D3479C(32) 

W-9, D3967(90) 

W-10, D3747(52) 

W-11, D3601 

FIGURE !.-Geologic map of the Jackson Purchase region, Kentucky, showing fossil localities. 

~ 

~ 

~ 

~ e"3 

1-1 

0 

!;d 

~ 

c.o 
10 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

clay breccia and clay-ball conglomerate occur at various horizons 

throughout the unit. The Cl·aiborne Formation, the thickest unit in the 

Eocene sequence, attains a maximum thickness of about 600 feet near 

the Mississippi embayment axis. 

The clay of the Claiborne Formation ordinarily occurs in widely 

spaced lenses and in many lenses is interstratified with argillaceous 

sand 1and silt, clean sand, and lignite. These lenses are as much as 50 feet 

thick and a mile across. The clay of the Claiborne Formation generally 

appears similar to that of the Wilcox Formation, although there are 

small differences in their mineralogic com positions. 

The contact with the Jackson Formation is poorly exposed and 

probably is gradational. 

JACKSON FOR~TION 

The Jackson Formation is composed, as are other Eocene units, of 

sand, silt, and clay. As in the Wilcox and Claiborne, the sand consists 

dominantly of angular to rounded, fine to coarse, granula.r quartz and 

minor amounts of dark minerals and muscovite. Some sand in the 

Jackson, unlike that in the Claiborne, contains several percent chert, 

which provides a means of distinguishing it from the Claiborne. It is 

not readily distinguished, however, from cherty sand in local lenses 

and beds in the continental deposits of Pliocene ( ? ) and Pleistocene 

age. 

Though poorly exposed, silt of Jackson age was penetrated in several 

test drill holes in the southwestern part of the region; a thickness of 

more than 250 feet was reported from one hole. The silt is commonly 

yellowish brown and sandy, and it contains coaly plant rem·ains at some 

horizons. 

Clay of Jackson age is dark to light gray, bluish gray, yellowish 

brown, and olive green. It is commonly sandy and micaceous ~and 

locally contains coaly plant material. In many outcrops along the bluffs 

of the Mississippi River, the clay is hard and brittle, and south of 

Hickm·an it commonly contains numerous irregularly shaped opallike 

masses as much as 5 mm across. 

Clay deposits in the Jackson Formation are thin to thick bedded and 

lenticular. Sequences consisting predominantly of clay and subordinately of silt are as much ·as 100 feet thick in areas bordering the 

Mississippi River in Fulton and southern Hickman Counties. These 

sequences thin and intergrade with sand northward and eastward. In 

updip areas, widely spaced lenses in the lower part of the formation 

resemble, in appearance and size, those of the underlying Claiborne 

Formation. 
CLAY PRODUCTION 11 

ECONOMIC GEOLOGY 

HISTORY OF CLAY PRODUCTION 

Although some clay was probably extracted commercially in the 

1820's during early settlement of the area, it was not until the late 

1800's that clay mining contributed significantly to the economy of the 

area. The industry received great impetus during World War I when 

importation of clay from European sources practically ceased (Whitlatch, 1940, p. 3), and by 1940, mines producing from Eocene strata of 

West Tennessee and the Jackson Purchase region of Kentucky were 

supplying more than 80 percent of the ball clay used in the United 

States. As shown in table 2, total clay production from the Jackson 

Purchase region, Kentucky, during the period 1900-60 amounted to 

more than 2,880,500 short tons valued at more than $25 million. Production figures for years after 1960 are not available. The bulk of ball 

clay produced in Kentucky came from pits in central and northern 

Graves County (see fig. 2). A small amount was from the La CledeChristy and American pits in Ballard County. All pits except one are 

in the Claiborne Formation; the Dunning clay pit in Graves County 

is in the Wilcox Formation. An unreported amount of pottery clay was 

produced from pits in McCracken, southeastern Ballard, and southern 

Graves Counties. 

TABLE 2.-Ball-clay production from the Jackson Purchase region, Kentucky, 190D-60 

[19oo-41, from Gildersleeve (1945, p. 111-112); 1942-60, compiled from U.S. Bur. Mines (1943-61)] 

Date 

1900-4 L _____ 

1942 _________ 1943 _________ 1944 _________ 1945 _________ 

1946 - - - -.. - - - - 1947 _________ 1948 _________ 1949 _________ 1950 _________ 

1951_ ________ 1952 _________ 

1953 _______ ,._ 1954 _________ 

1955 _________ 1956 _________ 1957 _________ 1958 _________ 1959 _________ 1960 _________ 

TotaL ___ 

Short tons Dollar value 

1,028,188 7, 789,476 

80, 259 696, 788 

69, 982 622, 309 

72, 729 669, 419 

80,077 744, 599 

98, 918 990,301 

99, 951 1, 072, 203 

103,426 1, 155, 530 

89,281 1, 076, 531 

105, 690 1, 325, 161 

111, 215 1, 411, 175 

107, 211 1, 372,695 

100,482 974, 637 

96,483 1, 263,526 

111,600 1,498,950 

115, 243 1, 501, 550 

102, 000 Not reported 

94, 200 1, 333,000 

111, 600 Not reported 102, 000 _____ do _______ 

2, 880, 535 25,497,850 

Remarks 

Not included are indeterminant 

tons, 1902-14 and 1919-20. 

Also, produced fire clay. 

Also, produced a substantial 

part of Kentucky's fire clay. 

Do. 
0 5 10 15 

FULTON 

CO., KY. 

~ a~ 

Co eo 

+" 

gg• 

./ <- <- l~yOJs 

~ Jackson Purchase 

region 

t-e 

~ 

@ 

~ 

t:l 

1::1 

"d 

0 

rll 

::3 

Jll 

1::1 

0 

Q 

1::1 

~ 

> !:;) 

__ 1::1 

~ 

~ Q 

~ 

~ 

~ 

'(f.J 

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~ 1::1 
i 

f 

A, LaCleade-Christy 

B, American 

C, Hall 

0, Unnamed 

E, Nieluiff 

F, Dunning(Boaz) 

G, Lamkin 

GA, Unnamed 

H, Warren 

EXPLANATION 

xZl 

Outcrop 

a1 

Drill hole 

Sample locality 

xl6 

Clay pit 

Number identifies sample described in table 3 

xP 

Active 

xU 

Inactive 

Clay pit 

Letter symbol identifies name of pit in following list: 

I, Excelsior P, Mayf'wld 

J, Cooley Q, Unnamed 

K, Powell R, Thomson and 

L, Chapman No. 3; Bennett-Phillips 

Blalock No. I S, South 40 

M, Blalock No.2 T, lJennett 

N, Campbell U, Unnamed 

0, Ray V, Bell City 

W, Srott, Monroe, Cole, 

and others 

X, Martin 

Y, Paschall No. 5 

Z, Etheridge, Wade, 

and others 

ZA, Milligan and 

Howard 

Frauu 2.-:Map ot the Jackson PUrchase region, Kentucky, and adjacent parts of Tennessee, showing 

location of samples and clay pits. 

8 

~ 

~ ~ 

t:J 

0 

~ 

.-

~ 
14 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

Much ball clay has been produced £rom pits in the Claiborne Formation in northern Henry County, Tenn. The tonnage o£ clay produced 

during 1938-£rom these pits, combined with that produced £rom other 

parts o£ Henry County and £rom Carroll and Weakley Counties, 

Tenn.-isreported by Whitlatch (1940, p.1). · 

GENERAL DESCRIPTION OF DEVELOPED CLAY DEPOSITS 

IN THE CLAIBORNE FORMATION 

The developed clay deposits in the Claiborne Formation are lenses 

in which the clay is interstratified with sand, silt, and lignite. The 

clay is thin to t.hickbedded and massive. Thickness o£ beds ranges £rom 

1 or 2 feet to more than 15 feet. In some deposits, clay with different 

qualities is produced £rom different beds, and aggregate thickness o£ 

all beds exceeds 30 feet. The quality o£ clay produced £rom a single bed 

may vary laterally and vertically. The manner in which the quality 

varies is shown by stratigraphic sections reported by Gildersleeve 

(1945, p. 99, 104, 108-109) and by illustrations and sections reported 

by Whitlatch ( 1940, p. 68, 82, 99). Thickness o£ overburden, which 

consists mostly o£ sand, gravel, and silt, is generally less than 60 feet, 

and the deposits are worked by open-pit methods. 

The areal extent and shape o£ developed deposits .are indica;ted, in 

a general way, by the size and shape o£ clay pits. In Kentucky, clay 

pits range £rom about% acre, barely 100 feet in longest dimension, to 

60 acres, about 1,000 feet wide and 2,500 feet long. Most pits have 

irregular outlines but in plan view are circular to elongate. The long 

dimension o£ the. elongate pits trends north to east-northeast. Most 

pits in the Claiborne Formation o£ Kentucky occur in a 2-mile-wide 

arcuate belt tha;t follows the general strike o£ the strata as shown on 

published geologic maps (Olive, 1963; Blade, 1965; Finch, 1965; 

Finch and Minard, 1966; Swanson and Wilshire, 1967). Fossil pollen 

indicates that sediments within the belt range £rom middle to late 

Claiborne age. About 20 miles southeast, another belt with a northerly 

trend is suggested by the shapes and arrangement o£ clay pits in 

northwestern Henry County, Tenn. Pollen assemblages (R. H. 

Tschudy, written commun., 1966) £rom clay deposits within this belt 

indicate that the belt contains sediments that range £rom lower to 

middle Claiborne age. 

ORIGIN OF CLAY DEPOSITS 

Seeking evidence concerning environments o£ deposition, R. H. 

Tschudy (written commun., 1968) examined pollen assemblages obtained from the Claiborne Formation at localities shown in figure 1. 

Many assemblages contain taxa, such as fresh-water algae and water 

£ern, that indicate deposition in lakes and fresh-water ponds. Others 
ECONON.UC GEOLOGY 15 

contain large spores that are not likely to have survived long-distance 

transport. A clay sample from "locality C-15 (fig. 1) yielded abundant 

hystrichospheres, a few dinoflagellates, and abundant plant tissue, 

which point to a marine or near-shore marine depositional environment. A sample from locality C-7 (fig. 1) contained much trash and 

a few hystrichospheres, which suggest a marine or brackish-water 

enviroment. The shapes and distribution of the clay bodies and the 

ooologic information provided from a study of pollen assemblages 

suggest that the climate during Claiborne time was warm and humid 

with heavy seasonal rainfall;· the terrain was a rather flat plain 

traversed by south- to east-flowing, meandering, low-gradient, aggrading streams that occupied broad flat shallow valleys. Flooding 

following .seasonal rains caused shifts in the major channels and 

abandonment of channel segments, which became. locales for accumulation of clay deposits and associated sediments. 

Stratigraphic and paleontologic evidence suggests that developed 

clay deposits in northwestern Graves County accumulated in a southerly trending valley. Less positive evidence indicates that depositsin 

the central part of the county were laid down at a .later time in a 

south- to west-trending valley. 

Six large and several small clay deposits west and south of Hickory, 

Ky., occur within a band lf2 to 1 mile wide and 8 miles long (Blade, 

1965). The band follows the general strike of the rocks; the northern 

two-thirds trends N. 50° W., and the southern part trends due north. 

Several clay deposits within the band have a northerly trend. All deposits are at about the same altitude; the bottom of each occurs within 

a 10-foot interval, between 430 and 440 feet in altitude. Four clay 

samples, C-10 through C-13 (fig. 1), from within the band are reported by Tschudy ( 1965a) to contain pollen assemblages of upper 

Claiborne age. The assemblages, though similar, are not identical, and 

according to Tschudy (1965a, p. 29) contain a"* * * particular type 

of peltate leaf hair * * *" that has not been recognized in other deposits from the area. The evidence suggests that the deposits were 

laid down at about the same altitude and at about the same time; the 

linear shape and trend of the band and individual clay deposits suggest that the deposits accumulated in a broad north-trending valley. 

Clay deposits of the Ray, South 40, Bennett, and Mayfield pits (fig. 

2) in central Graves County are also at a nearly concordant level. The 

bottom of each deposit is between 410 and 445 feet altitude. The outlines of the Bennett and Mayfield pits are elongate and trend about 

N. 75° E. and N. 80° E., respectively; the Ray and South 40 pits have 

cireular shapes. The pits are within a band that trends at an oblique 

angle across the general trend of the Claiborne Formation. Although 
16 CLAY DEPOSITS, EOCENE AGE, KENTUCKY .AND TENNESSEE 

one might expect the deposits to decrease in a.ge westwa.rd in the direction of the regional dip, p·alynologic evidence suggests that they are 

about the same age. Pollen samples C-3, C--4, C-6, and C-9 (fig. 1) 

from the South 40, Bennett, Mayfield, and Ray pits, respectively, and 

samples C-5 and C-8 from undeveloped clay deposits within the band 

contain assemblages that a.ccording to Tschudy ( 1965a, 1965b) are 

common to the Cockfield (uppermost Claiborne) and 1\'Ioodys Branch 

(lowermost Jackson) Formations in Mississippi. If the deposits are 

the same age, their distribution suggests that they were deposited during late Claiborne time in valleys that trended south to west across 

older sediments. 

KINERALOGY 

As shown by X-ray analyses (table 3), all samples of clay deposits 

consist predominantly of quartz and clay minerals ; size analyses (table 

4) show that these minerals occur as clay-, silt-, and sand-size particles. 

A few samples contain as much as several percent cristobalite and 

plagioclase; some contain dolomite, calcite, and potassium feldspar, 

ranging in amounts from a trace to as much as 1, 2, and 3 percent, 

respectively. Samples 16, 21, 27c, and 28b (table 3) contain as much 

as 1 percent feldspar, which was not identified acoording to type. 

Clay minerals, listed in order of most common occurrence, are kaolinite, mixed-layet" clay, illite, montmorillonite, and chlorite. Kaolinite 

is the only clay mineral that occurs in all 36 s~mples; it is dominant 

in 29 and shares primary rank with montmorillonite in one (table 3). 

Mixed-layer clay and illite, which are present in all but a few samples, 

generally occur in small to moderate amounts, but in some samples 

they are abundant; in two samples mixed-layer clay is dominant. 

Montmorillonite occurs in a little more than half the samples and is 

dominant in four. Beidellite is a component of the mixed-layer clay 

in sample 2. Chlorite is a minor clay-mineral constituent in five samples 

(table 3). 

Tests conducted on 15 of 33 samples containing mixed-layer elay 

show that mixed-layer clay in 10 samples contains more illite than 

montmorillonite; in four samples it contains more montmorillonite 

than illite; and in one sample montmorillonite and il1ite are eqnal 

(table 3). 

The mineralogic composition of clay deposits (table 3) varies according to the stratigraphic position of the deposits. Analyses of seven 

samples suggest that clay deposits of the Wilcox Formation are composed mostly of kaolinite and illite. Montmorillonite, mixed-layer clay, 

and chlorite occur in small amounts in some Wilcox samples and are not 

present in others. The major constituent of c1ay deposits of the Claiborne Formation is kaolinite. In all 11 Claiborne samples, kaolinite 
TABLE a.-Description and x.ray mineralogic analyses of clay samples from the Jackson, Claiborne, and Wilcox Formations 

[Includes two sand samples for which the clay traction was investigated. X-ray analyses by R. P. Christian (indicated by asterisk) and H. A. Tourtelot, using methods described by Schultz (19M), except that total clay is reported as the difference between the sum of the nonclay minerals and 100 percent. Precision of determinations generally within 10 percent. Italicized numbers are estimates outside the normal interpretation of X-ray data. t indicates sample tested to determine ceramic properties, p. 42-63. 

Whole-rock analyses, in percent, calculated fl"om X-ray diffraction data. illite includes clay-size mica, chiefly muscovite] 

Whole-rock analyses, Clay-mineral fraction, 

Kentucky in percent in percent 

coordinates 

aa.:;:gle (coordinate .E system ! 38-i locality Description of location (71-rminute quadrangle, county, shown on Lithologic 

i ~ on map and State) U.S. Geol. description 

~~~~ (see Survey fig. 2) :! topographic G> 

~ [f. :>. maps of ~ I ·I G> ~ G> i ~ 'CI.!! Kentucky) ~ 'U ~ ~ . .§ fii'i G> N 

i ~ ~ ..9 «< G> ~ ~~g~ ~ ::s "5 «< 0 "5 ~ ~ ~ ~ :a Ci 0 ii:: ll-i 0 A E-4 ll-1 0 

Jaekson Formation 

L* -------- Outcrop (shown in Finch, 1963)\vwest side of U.S. Route 45, 1, 107,750 Light-gray, 42 ---- ? ? ? ? 58 33 11 20 36 M>I --- 2.5 miles north of center of ater Valley, Water Valley 110,800 slightly carbon- quad., Graves County, Ky. aceous, silty 

!* -----·-- Outcrop (shown in Finch, 1963) at altitude 420 feet, 0.43 mile clay. 1,088, 900 _____ do _____ -------_ 27 1 ---- 1 ---- ~--- 71 34 8 47 11 M>l --- south-southwest of Mount Zion Chapel, Water Valley 101,550 quad., Hickman Countb, Ky. 

I*-------· Outcrop (shown in Fine , 1963) at altitude 440 feet, 0.24 1,088,900 ••.•• do __________ --- 72 ---- ? ---- ---- ---- 28 75 8 15 2 M>l mile --- southwest of Mount Zion Chapel, Water Valley quad., 103,900 

l*- -------

Hickman County, K~. 

Outcrop in Chalk Bluff bordering Mississippi River, Wolf 1,010,800 L~ht-gray, 27 ......... ---- ? ---- ......... 73 51 7 14 28 M=l --- Island quad., Hickman County, Ky. 161,100 ightly carbonaceousand 

micaceous, silty 

~·t- ------ Railroad cut, 0.24 mile north-northwest of Baltimore clay. 1,100,400 Dusky-brown, 53 ---- ? ? ? ? 47 65 8 I>M ---- 27 Church, Dublin --- quad., Hickman County, Ky. 140,550 slightly carbo- naceous and 

micaceous, silty 

J*f------- Railroad cut, 0.83 mile north-northeast of Jackson Chapel, clay. 1,093, 950 I>M _____ do ________ ----- 46 ---- ---- ---- ? ? 54 72 14 ........ 14 --- Dublin quad., Hickman Counth, Ky. 126,200 rt _ ------- Drill hole 44 of Olive (1967), dept 22-47 feet, 1 mile east of 1, 015,100 Light-grayish- 23 77 50 ---- 50 

Mount ---- -------- --- Harmon Church, Cayce quad., Fulton County, 85,250 brown clay. Ky. 

l!';j 

g 

~ 

~ 

~ 

g 

~ 

"-' "' 
TABLE 3.-Description and X-ray mineralogic analyses of clay samples from the Jackson, Claiborne, and Wilcox Formations-Continued 

Whole-rock analyses, Clay-mineral fraction, 

Kentucky 

in percent in percent 

coordinates 

Sample (coordinate .s and system locality Description of location (7)1-minute quadrangle, county, shown on Lithologic c. 

til .£8~ 

~ on map and State) U.S. Geol. description ~ 0) ·a - :a .... o$o (see Survey fig. 2) topographic 0) 

cD ~ 0 ~:as~ maps of ~ ~ -~ ~ ~ ~ cD :a go"O~ 

Kentucky) te t3 t3 :a 0 .... a g~ cD 

"' ..a 0) s :6 ~1:3----"' ~ 

~ 0 0 

~ =a "; ;::l 

~ -~ 0 cD 1:3 -~ Q,O~·§ 0 

0 "; '0 0 g 3 0 8El'-' :a cY 0 P:: ~ 0 ~ E-1 ~ H ~ ~ ~ 0 

Jackson Formation -Continued 

'"--------' outorop, 0.1 milo"""' of oud of H!-.n "'wall, Hlokmau I 990,050 Upper clay, con- I 16 I 61 8 I ____ L_ _ _I ___ _I 70 I 18 l ___ _l 52 I 30 , ________ , ____ 

quad., Fulton County, Ky. 105,750 tains biotite and 

8b ________ I _____ do ______________________________________________ ------ ___ volcanic glass. I 18 l ___ _l 8 I ___ J ___ _i ___ _i 74 I 990,050 Pale-grayish- 31 4 I 78 I 10 

105,750 yellow, blocky, silty clay. 

8c ________ l _____ do---.------------------~----------.-----~----~------------~ ~~;~gg L~~~~~~- 121 I 7~----j----j----j----~72130 ~----~60 120 , ________ , ____ 

9a________ Outer~ m low cuts along drrt road at Junction w1th Tennes- -------------- Opalized clay _____ 35 11 ________________ 54 70 ____ 16 16 , ________ , ____ 

see oute 22, 0.5 mile northeast of Samburg, Samburg quad., Obion County, Tenn. 

Db-------+----do ______________________________________________________ +-------------1 Fragmental clay --130 I 71---+--+---1-·--1 63 1 54 1----117 1 29 1 _______ T ___ 9c _____________ do ______________________________________________________ -------------- Soft clay between 35 7 ________________ 58 58 4 23 15 ____________ 

buttresses of 

10-----. ··I Outm-op In <oadeut of Ton ...... Rout• 22, 3 mn.. ......... I"---.--------. c~;'.~~:.... ·1''1 10 ~--~----~- -j-···1"1'"1 12 122 111 of Samburg, Samburg quad., Obion County, Tenn. , ____ - _, ---

11 * _ _ _ _ _ _ _ Sample from depth of 105 feet in drill hole on east shore of 972, 300 Greemsh-gray, 25 ____ 2 2 ____ ____ 71 15 7 33 45 , ________ , ____ 

Mississippi River, about 2.5 miles north of Hickman, Hick- 101, 350 slightly micace- man quad., Fulton County, Ky. ous, silty clay. 

Claiborne Formation 

12* _ ------ Paschall No.5 clay pit, 4.1 miles northeast of Cottage Grove, -------------- Brownish-gray 4 ---- ---- ? ---- ---- 96 70 5 ---- 25 I>M --- Cottage Grove quad., Henry County, Tenn. · ball clay. 

13* ------- Etheridge mine, 4.3 miles east-northeast of Cottage Grove, -------------- Pale-gray sagger 23 ? 77 83 6 ---- 11 I>M --- Cotta~e Grove quad., Henry County, Tenn. clay. 

14*-------- Scott mme, 2.35 miles southwest of junction of U.S. Route -------------- Dark-gray wad 34 ? 1 65 79 14 ---- 7 I>M --- 641 and Tennessee Route 140 in Puryear, Puryear quad., clay. Henry: County, Tenn. . 15*- ------ Clay p1t (shown in Olive, 1963), 0.4 mile southeast of Bell 1, 192,950 White clay ________ 34 1 1 1 63 67 9 ---- 24 I>M --- City, Lynn Grove quad., Calloway County, Ky. 84,550 

,........ 

00 

C":l 

s 

t::1 

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16.-------

17a _______ 

17b _______ 

18*t- -----

19*t ------

20*t- -----

21 t-------

22.-------

23*t ------

24*- ------

25.-------

26--------

27a ______ _ 

27bf _____ _ 

Lamk:in clay pit (shown in Blade, 1Yo5), 2 mues west-north- west of West Viola, Ky., Hickory quad., Graves County, 

M~~ie of Powell pit (shown in Blade, 1965), 1 mile southeast 

of Hickory, Hickory quad., Graves County, Ky. 

Bottom of Powell pit----------------------------------------

Outcrop, 0.4 mile east of Wickliffe City limia north side Ken- tucky Route 440, Wickliffe quad., Ballar County, Ky. Outcrop, 3.8 miles east of Lovelaceville in -illinois Central 

Railroad cut, 450 feet north of overpass at south end, Lovelaceville quad., McCracken County, Ky. 

Outcrop (shown in Olive, 1966), 0.75 mile south of Camelia, 

Heath quad., McCracken County, Ky. 

Outcrop (shown in Olive, 1966), 0.9 mile north-northeast of 

Camelia, Heath quad., McCracken County, Ky. 

Dunning clay pit (shown in Finch, 1964), 0.3 mile north- west of Mount Pleasant Church, Symsonia quad., Graves 

County, Ky. 

Outcrop (shown in Wilshire, 1963), 0.25 mile northwest of 

Collie Cemetery, Kirksey quad., Calloway County, Ky. 

Outcrop (shown in Olive and Davis 1968), 0.43 mile east- southeast of Brewers School, Oak Level quad., Marshall 

County, Ky. 

Outcrop (shown in Olive and Davis, 1968), 0.6 mile southeRSt of Smith Cemetery, Oak Level quad., Graves County, Ky. 

Outcrop (shown in Olive and Davis, 1968), 0.1 mile west of 

minnow pools on Moss Branch, Oak Level quad., Marshall 

County, Ky. 

Drill hole G of Finch (1966), 2 miles south-southeast of Lone Oa~ altitude 429-439 feet, Paducah West quad., McCrack- en vounty, Ky. Drill hole G, altitude 424-429 feet_ __________________________ _ 

27c. _____ J Drill hole G, altitude 419-424 feeL _________________________ _ 

Average, sample 27 ___________________ -- ________________ _ 

28af ____ __j Outcrop (shown in Olive and Davis, 1968), 1.5 miles west- southwest of Oak Level, Oak Level quad., Graves County, Ky. 28b ______ _!--- __ do ______________________________________________________ _ 

Average, sample 28 _________________ --- ___ ---------------

1, 137,600 Pale-gray clay ____ 20 ____________________ 80 70 22 206,800 ---- 8 -------- ---

1,147,400 _____ do_-- _________ 20 

187,900 ---- ---- ---- ---- ---- 80 90 5 ---- 5 -------- --- 1, 147,400 _____ do _______ ------ 18 

187,900 ---- ---- ---- ---- ---.. 82 77 13 ---- 8 -------- 2 

1,028,800 Gray clay _________ 43 ---- ? ? ? ? 57 61 8 16 15 M>I 245,800 --- 1, 121,000 Dark-gray 31 ---- ? ---- ? ? 69 68 9 3 20 I>M 247,450 --- carbonaceous, 

slightly silty 

clay. 1,117,250 White clay_------- 26 

261,300 ---- 2 ---- 2 ? 70 76 9 ... ........ 15 I>M --- 1, 118,600 Tan clay __________ 23 ---- ---- .......... ---- ---- 77 72 18 ---- 10 -------- --- 269,600 

Wileox Formation 

1, 161,500 

229,300 

1, 212,100 

159, 150 

1, 214,600 

170,450 

1, 198,700 

176,100 

1, 202,700 

174,000 

1, 150,700 

259,300 

1, 150,700 

259,300 

1, 150,700 

259,300 

1, 150,700 

259,300 

1, 198,100 

204,000 

1, 198,100 

204,000 

1, 198,100 

204,000 

Pale-gray clay _____ 37 ---- ---- ---- ---- ---- 63 65 23 5 

7 --------,----

Dark-grayish- 32 ........... 1 ---- 2 1 

brown clay. 

64 54 43 ---- 3 I>M 

White clayey 62 ---- 1 ---- ? ? 37 87 10 ---- 3 I>M "sawdust 

sand." 

White sandy I 23 1----1----1----1----1----1 77 I oo , ____ , ____ , ____ , ________ , ____ pisolitic clay. 

White clayey I 70 1----1----1----1----1----1 30 I 84 I 14 1----'---.1 _______ _1 sand, "sawdust 2 

sand." 

Dark-olive-gray, I 25 1----1----1 3 1----1----1 72 I 48 I 16 I 26 I 10 , ________ , ____ nearly silt-free 

---'~l"- ----------171 ~----~----~----~----t----173128120 1261181 _______ 1 8 _____ do _____________ 18 ____________________ 82 35 10 20 22 -------- 13 

_ ____ do _____ --- ____ -l (23) 1----1----1----1-___ , ___ .I (77) I (37) I (15) I (24) I (17) 1--------1 (7) 

Unweathered 

clay. 

27 l ___ _j ___ _J ___ _I ___ _J ____ \ 73 I 55 I 31 I ____ \ 14 ·--------·----

Weathered clay ____ ,33~----~----~----~----~----~67162138 ----~----·--------·---- (Clay) ___________ (30) ____________________ (70) (59) (34), ____ (7), ________ , ___ _ 

t:'::t 

8 

z 

(") 

~ 

~ 0 

t"4 

0 

~ 

1-l 

~ 
TABLE 4.-Size analyses of whole-rock samples from the Jackson, Claiborne, and Wilcox Formations 

[Analyses by R. P. Christian. Particle sizes 0.062-1.0 mm determined by dry-sieve method; sizes below 0.062 mm by Bouyoucos (1936) hydrometer method. See figure 2 for 

sample localities and table 3 for mineralogic analyses of each sample] 

Cumulative percent smaller than particle size, in millimeters 

Formation Sample Sand Silt Clay 

1.0 0.7 0.5 0.35 0.25 0.175 0.125 0.088 0.062 0.031 0.004 0.002 0.001 

1ackson Formation._---····-···-·-------- 1 ------------------------------ <100 <100 <100 99.8 97.6 93.2 77.9 41.8 38.0 24.6 

2 -----------------. ··-----------.-------- <100 99.9 99.5 98.6 97.6 86.7 48.8 46.9 37.1 

3 99.9 99.9 99.9 99.8 99.7 99.2 86.6 57.7 42.7 31.0 20.1 15.2 14.4 

4 -------------------------------------------.------ <100 99.9 98.4 92.8 71.6 35.2 31.9 17.4 

5 ---------------------------------·---------------. <100 <100 99.9 99.6 79.3 31.9 29.1 14.8 

6 ---------- <100 <100 <100 <100 <100 <100 99.8 98.0 72.1 35.3 34.9 24.7 

Claiborne Formation _______________ -----·- 12 ---.------------------------·---.------- <100 99.6 98.8 97.7 96.8 80.3 66.8 63.9 50.8 

13 ---------- <100 <100 <100 <100 99.9 99.5 97.9 95.3 84.8 74.8 74.8 61.5 

14 ---------·--------------•• -.-.---------- <100 99.9 99.7 911.1 97.5 84.2 46.8 41.7 28.1 

15 ---·-------------------------------------------------------- <100 99.9 99.6 90.4 53.4 52.6 31.9 

18 -----·· ---· -· ••• ---------------·--------•• ------------------ 99.9 99.7 97.8 75.5 44.2 41.5 27.4 

19 -------------------------.-------.------ <100 <100 <100 99.8 99.2 87.7 58.7 52.7 43.6 

20 •• -----------------.-----------------·-·-------------------- <100 <100 99.9 95.9 75.9 73.9 58.9 

Wilcox Formation·-------------------····· 23 <100 <100 <100 <100 <100 <100 <100 <100 99.9 92.4 81.4 76.4 54.5 

24 <100 <100 99.9 98.5 96.1 77.7 57.4 42.7 37.3 32.1 22.3 19.5 15.0 

1:-.:) 

0 

c 

E 

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tr.l 

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0 

~~ tr.l 

g 

~ 

~ 

~~ 

= 

~ 

~ ~ 

~ 

t;J 

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E 

~ 
ECONOMIC GEOLOGY 21 

makes up nearly two-thirds or more of the clay-mineral fraction. Illite 

and mixed-layer-clay contents are variable, but neither exceeds 25 percent of the clay fraction. Only two Claiborne samples contain montmorillonite. The composition of clay deposits in the J a.ckson Formation varies over a wide range. Kaolinite is the dominant clay mineral in 

8 of 15 samples; amounts of kaolinite and montmorillonite are equal 

in one; montmorillonite is dominant in four; and mixed-layer clay is 

dominant in two. Montmorillonite, ranging in amounts from 14 to 78 

percent, is present in ·all but three samples. 

Size analyses of samples from 15 clay deposits, four of which are 

developed, are presented in table 4. The combined sand and silt content in each sample, except samples 20 and 23, exceeds by as much as 

37.8 percent the amount of quartz determined by X-ray ·analysis (table 

3) . This relation implies that in all but two samples a part of the fraction reported as silt is composed of aggregates of grains. A rather 

small number of aggregates of grains probably occurs in the sand-size 

fraction, which makes up less than 10 percent, and generally less than 

5 percent, of all samples except samples 3 and 24; sample 24 is from a 

sand deposit. In samples 20 and 23, the sand and silt content is exceeded 

by the amount of quartz, a fact indicating that some quartz is contained in the clay fraction. Thus, if discrete grruins cannot be distinguished from aggregates of grains, ·accurate size analyses cannot 

be made, and comparison of data between samples will be misleading. 

The data, however, do have value as an index to the degree of disaggregation of clay particles and can indicate the maxima and minima 

within the various size ranges. For example, the data reported for 

sample 1 show that the clay-size-particle content cannot be less than 

41.8 percent and the sand content cannot be more than 6.8 percent. The 

maximum amount possible for silt would be 58.2 percent, even if all 

material reported as sand were composed of aggregates of silt grains. 

Sand-content maxima in four commercially developed deposits, 

represented by samples 12-15, range from 0.4 to 4.7 percent, and silt 

maxima range from 25.2 to 53.2 percent. The minima for clay range 

from 46.8 to 7 4.8 percent. Size analyses ,of sa.mpi'es 2, 19, 20, and 23, all 

from undeveloped deposits, are comparable to those from the commercially developed deposits. 

TYPES OF CLAY 

In the ceramics and clay-mining industries, clays are variously 

typed or classified according to their ceramic properties and use, 

source of origin, and mineralogic composition. Most clays produced 

from Eocene rocks of Kentucky and Tennessee are broadly classified as 

fire clay, which includes several types of clay resistant to heat. Based 

largely on their uses, they are designated by the trade names ball, wad, 
22 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

and sagger clay. The following descriptions are summarized from 

Whitlatch (1940, p. 11-12) : 

Brill clay.-Very fine grained to colloidal, essentially grit-free, 

highly plastic; characterized by high-bonding power. The best ball 

clays have high green strength, are white to near white and ivory when 

fired and have high density at oertain temperatures. 

Wad clay.-"* * *possesses a high degree of plasticity and ·toughness, making it suitHhle for rolling into the long strips or 'wads' used 

for grouting joints of saggers when they are set up in bungs in the kiln. 

[It is] characterized by a fairly high content of fine-to-medium-grained 

silica and is, consequently, sufficiently open-firing at moderately high 

kiln temperatures to prevent sticking of the wad to the sagger." 

Sagqer clay.-Strongly plastic clay that is fairly refractory but resistant to repeated heating and cooling; any clay-including ball, wad, 

and sandy day-that is suitable for "making sa.ggers, the containers in 

which delicate pottery wares are placed for protection from dirt and 

kiln gases during firing." 

RELATIONS BETWEEN TYPE AND MINERALOGY 

The clay type is determined by many interdependent factors such as 

mineralogic composition, grain size, and the presence of a·ccessory 

components such as organic material, soluble salts, and ferric, titanium, 

1nagnesium, and calcium oxides. Of these factors, only those determined by X-ray-diffraction and size analyses are dealt with in this 

report. 

Grim (1962, p. 147) observed that plastic fire clays are composed 

largely of kaolinite, small amounts of illite, and, at times, montmorillonite. Published literature contains little information on permissible 

percentages of these minerals in fire clay. 

Montmorillonite, though used in small quantities as a plasticizer 

in otherwise low-plastic clay, is undesiraible in large amounts in the 

manufacture of fine ceramics. It has excessively high shrinkage, and 

because it fires to a buff or reddish color, it is undesirable in the manufacture of products such as whiteware. Information on percentages of 

montmorillonite allowable for the various groups of clay is sketchy. 

Parker, Warren, •and Morcom (1951) give evidence to indicate the 

presence of sm1all amounts of montmorillonite in china clays; and 

Smoot (1963, p. 311) reports: "Although a certain amount of montmorillonite is generally found in ball clays, the proportion rarely exceeds 10 percent." It is assumed from the foregoing that more than 2 

or 3 percent of montmorillonite is undesirable in china clays and that 

more than 10 percent is deleterious in most ball clays. 

In a study of British clays used in the fine ceramic industries, 

Holdridge ( 1963) calculated mineralogic composition on the basis of 
ECONOMIC GEOLOGY 23 

100 percent kaolinite, mica, and quartz. The composition of each clay 

type studied by Holdridge varies, with some exceptions, within the 

limits given in truble 5. 

TABLE 5.-Range in percent of kaolinite, mica, and quartz in clays used in British 

fine ceramics industries 

[Compiled from Holdridge (1963, p. 353-354)] 

Range in percent 

Types of clay Kaolinite Mica Quartz 

China__________________________________________ 70-95 

Ball: 

Best potting clay~--------------------------- 60-90 

Second-quality ball clay and stoneware clay_____ 30-60 

Siliceous ball clay____________________________ 15-40 

Fire____________________________________________ 30-80 

I An undefined term used by Holdridge, possibly to indicate pottery clay. 

4-26 

5-30 

15-40 

5-25 

5-25 

0-7 

0-20 

10-45 

45-75 

10-60 

In identifying the minerals and deriving the percentages reported 

in table 5, Holdridge apparently combined da;ta from X-ray and 

chemical analyses. According to Holdridge (1963, p. 352), "* * * alkali associated with clays has been attributed to mica which has been 

calculated as a mixture of muscovite and paragonite." Mica, as reported 

by Holdridge, is equivalent to the illite, montmorillonite, mixed-layer 

clay, and chlorite of the X-ray analyses in table 3. These minerals, 

designated IMC are grouped together in ta;ble 6 to show the amount 

of material supplying sodium and potassium to the clay mixture for 

comparison with Holdridge's mica. Cristobolite is grouped with quartz. 

Mineralogic compositions of samples 12-16, 17a, 17b, and 22, all from 

developed clay deposits, approximate compositions reported for British 

ball clays (compare tables 5, 6). Compositions of samples 19-21 and 23, 

all from undeveloped clay deposits, approximate those of British and 

locally produced ball clays. The composition of sample 18 is comparable 

to that of fire clay in table 5, and the composition of sample 6 compares 

favorably with that of either fire clay or siliceous ball clay. The 

composition of other samples does not compare favorably with tha;t of 

British or locally produced commercial-grade clays, either because the 

samples contain lower percentages of kao1inite and sources of alkali 

or because the montmorillonite content exceeds 10 percent. 

The four samples in table 3 that have 1 to 3 percent calcite or calcite 

and dolomite contain about 1 to 2 percent CaO and MgO. These 

amounts are larger than those found by Holdridge (1963, p. 359-363). 
24 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

TABLE 6.-Calculated kaolinite, other clay minerals (I MC), and quartz content of 

clay samples from the Jackson, Claiborne, and Wilcox Formations 

[Calculated from data for corresponding samples in table 3] 

Percent Percent 

Sample Sample 

Kaolinite IMC Quartz Kaolinite IMC Quartz 

Jackson Formation Clairbore Formation-continued 

l _____ · _____ 19 39 42 14 ________ 52 14 34 2 __________ 24 48 28 15 ________ 43 22 35 3 __________ 21 7 72 16 ________ 56 24 20 4 __________ 37 36 27 17a _______ 72 8 20 5 __________ 31 16 53 17b _______ 63 19 18 6 __________ 39 15 46 18 ________ 35 22 43 7 __________ 39 38 23 19 ________ 47 22 31 8a _________ 14 62 24 20 ________ 55 18 27 8b _________ 2 78 20 21_ _______ 56 21 23 8c _________ 22 50 28 9a _________ 38 16 46 Wilcox Formation 9b _________ 34 29 37 9c _________ 34 24 42 22 ________ 41 22 37 10 _________ 12 15 73 23 ________ 36 31 33 ll _________ 11 63 26 25 ________ 77 0 23 

27a _______ } 

Claiborne Formation 27b _______ 28 49 23 27c _______ 12 _________ 67 29 4 28a _______ } 13 _________ 41 29 30 64 13 23 28b _______ 

DESCRIPTION, CERAMIC PROPERTIES, AND POTENTIAL 

USE OF UNDEVELOPED CLAY DEPOSITS 

In order to determine their ceramic properties, samples of several 

clay deposits, for which mineralogic analyses are reported in tables 

3 and 6, were tested by laboratories of the U.S. Bureau of Mines 

(USBM). A brief description of the geography and geology of each 

deposit and the results of ceramic tests are presented below. The darta on 

ceramic properties are based on preliminary laboratory tests and will 

not suffice for plant or process design. 

SAMPLE 5 

(USBM Lab. No. K-3-2) 

Location and altitude: Cut bank along east side of Illinois Central Railroad, 

0.24 mile NNW. of Baltimore Church, Dublin 7%-min quad., Kentucky; 330 

ft alt. 

Nearest railroad: Immediate vicinity. 

Stratigraphic position: Jackson Formation. 

Description of clay body : Total thickness, not determined ; 10 ft thick in outcrop ; 

consists of silty, carbonaceous, dusky~brown clay exposed over a distance of 

300ft in cuts adjacent to railroad; intergrades with sand at south end of exposure and is truncated by erosion at north end. 

Overburden : 7-8 ft of sand ; 15-20 ft of gravel ; and 12 ft of. silt. 
PROPERTIES AND USE, UNDEVELOPED CLAY DEPOSITS 25 

Raw properties: Low plasticity; water of plasticity, 35.7 percent; drying shrinkage, 2.5 percent; dry streng;th, low ; drying defects, none; pH, 4.4; color, gray; 

not effervescent in HOI. 

Slow-firing test: 

Temperature eF) Color Hardness 

1,800 ___________ Cream _______ Poor bond ___ _ 1,900 ________________ do ____________ do ______ _ 2,000 ________________ do ____________ do ______ _ 

2,100 ___________ Ivory________ 3 

2,200 ________________ do_______ 3 

2,300 ___________ Gray________ 3 

Percent Percent Bulk 

total absorption density shrinkage 

5. 0 

5. 0 

5. 0 

7. 5 

7. 5 

10.0 

32. 2 1. 40 

30. 7 1. 42 

22. 7 1. 57 

Remarks: Low green strength; poor ceramic bond; high absorption at all temperatures; pyrometric cone equivalent, 23. 

Bloating test: Negative. 

Potential use : Body component in artware and for stoneware or gla'Zed structural 

tile mixtures. 

SAMPLE 6 

(USBM Lab. No. K--8-8) 

Location and altitude: Cut bank along west side of Illinois Central Railroad, 

0.83 mile NNE. of Jackson Chapel, Dublin 7%-min quad., Kentucky; 440 ft alt. 

Nearest railroad: Immediate vicinity. 

Stratigraphic position: Jackson Formation. 

Description of clay body: 15ft of silty, carbonaceous, dusky-brown clay; poorly 

exposed in east-facing cut; weathers dusky brown in upper part of expo~ure; 

size and thickness, not determined. 

Overburden: As much as 30ft of gravel and 15 ft of silt; 10-15 ft of sand may 

occupy the zone between the clay and the gravel. 

Raw properties : Low plasticity ; water of plasticity, 33.6 percent; drying shrinkage, 2.5 percent; dry strength, low ; drying defects, none; pH, 5.9; not 

effervescent in HOI. 

Slow-firing test : 

Percent Percent Bulk 

Temperature (°F) Color Hardness total absorption density shrinkage 

2 2. 5 30.2 1. 40 

2 2. 5 30. 1 1. 39 

2 2. 5 24. 4 1. 47 

3 5. 0 23. 4 1. 52 

3 5. 0 28. 1 1. 45 

3 5. 0 25. 3 1. 49 

1,800 ___________ Cream __________ _ 1,900 ________________ do __________ _ 2,ooo ________________ do __________ _ 

2,100 ___________ Ivory ___________ _ 2,200 ________________ do __________ _ 

2,300 ___________ Gray ___________ _ 

Remarks: Low green strength; poor ceramic bond; high absorption at all temperatures; pyrometric cone equivalent, 23. 

Bloating test: Negative. 

Potential use : Body component in artware and for stoneware or glazed structural 

tile mixtures. 
26 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

SAMPLE 't 

(USBM Lab. No. 1665-D) 

Location and altitude: Auger hole drilled at 328 ft alt, 1.17 miles N. 48o E. of 

the village of State Line, Cayce 7%-min quad., Kentucky (Olive, 1967), Sample 

is from between altitudes 281 and 306ft. 

Nearest railroad: 3.5 miles E. (Railroad through State Line, Ky., on topographic 

map of Cayce quad. has been removed.) 

Stratigraphic position: Jackson Formation. 

Description of clay body: Not exposed. Total thickness, not determined-auger 

penetrated 25ft of clay between depths of 22 and 47ft without reaching base; 

3-12ft of clay similar in appearance to that of sample 7 was penetrated in four 

·auger holes drilled within a radius of 1.4 miles, south and west of the sample 

7 locality. 

Overburden: 22 ft of silt; sandy and slightly pebbly in lower 1 ft. 

Raw properties: Long-working, smooth, plastic; water of plasticity, 44.8 percent; 

drying shrinkage, 7.5 percent; dry streng~th, fine; drying characteristics, good, 

very slight scum. 

Slow-firing test : 

Temp.erature (F) Color Hardness 

1,800 _______ Pinkish-gray ____ Hard _______ _ 1, 900 _______ Cream ______________ do ______ _ 

2,000 ____________ do _________ Very hard ___ _ 2, 100 _______ Buff ________________ do ______ _ 

2,200 _______ Buff gray _______ Steel hard ___ _ 2,300 _______ Light gray ___________ do ______ _ 

Percent 

linear 

shrinkage 

7. 5 

7. 5 

9. 0 

11. 0 

11. 0 

11. 0 

Percent 

absorption 

5. 0 

6. 8 

8. 9 

12. 0 

20.6 

58. 0 

Approximate specific 

gravity 

2. 57 

2. 54 

2. 50 

2. 48 

2. 32 

2. 25 

Remarks: Light color; shrinkage, a little high; absorption, high; scum, barely noticeable. 

Bloating test: Negative. 

Other tests: Solu-Bridge K factor, 5.00. 

Potential use: Stoneware and pottery, if washed and quartz added. 

SAMPLE 18 

(USBM Lab. No. K-3-1) 

Location and altitude: Natural exposure in south-flowing stream, 0.4 mile E. of 

east city limit of Wickliffe, 100ft N. of Kentucky Route 440, Wickliffe 7%-min 

quad., Kentucky and Missouri ; 300 ft alt. 

Nearest railroad : 0.4 mile S. 

Stratigraphic position: Claiborne Formation. 

Description of clay body: Natural exposure; consists of 4 ft of light-gray clay 

that contains fragments of carbonized wood, overlain by 2 ft 7 in. of lignite 

that, in turn, is overlain by 8ft of light-gray clay ; sample from lower clay bed ; 

base, not exposed. Drill hole 200 ft S. penetrated 52 ft of clay between altitudes 

307 and 359 ft. 

Overburden: As much as 15-20 ft of interlayered sand and clay, and approximately 40ft of gravel and 10ft of silt in upland areas to east and west. 

Raw properties: Moderate plasticity; water of plasticity, 26.4 percent; drying 

shrinkage, 5.0 percent ; dry strength, good ; drying defects, none ; pH, 7.5 ; 

color, gray ; not effervescent in HC1. 
PROPERTIES AND USE, UNDEVELOPED CLAY DEPOSITS 27 

Slow-firing test: 

Percent Percent Bulk 

Temperature (°F) Color Hardness total absorption density 

1,800_____ _ _ _ _ _ _ _ _ Light tan ________ _ 1,900 __________________ do __________ _ 2,000 __________________ do __________ _ 

2,100 _____________ Buff __________ _ 2,200 __________________ do __________ _ 

2,300 _____________ Gray ___________ _ 

3 

3 

3 

3 

4 

5 

shrinkage 

5.0 

5.0 

7.5 

7.5 

7.5 

7.5 

Remarks: Good buff color at 2,200° F; pyrometric cone equivalent, 20. 

Bloating test: Negative. 

19.2 

18.4 

16.4 

13.8 

13.3 

12.3 

1. 70 

1. 73 

1. 78 

1. 83 

1. 85 

1. 84 

Potential use : Flue lining; might also 'be suitable for medium-weathering-grade 

face 'brick. 

SAMPLE 19 

(USBM Lab. No. X-3-5) 

Location and altitude : Illinois C€ntral Railroad cut, known locally as Coleman 

cut, 3.8 miles E. of Lovelaceville, Lovelaceville 7%-min quad., Kentucky (Finch, 

1968) ; 406--409 ft alt. 

Stratigraphic position : Claiborne Formation. 

Description of clay body : Exposed for nearly 3,000 ft along strike and for 700 ft 

in dip direction; more than 40 ft thick. Alt sample locality, top i,s at 423 ft alt, 

and 'base is at 380 ft. Clay qua1rried from the abandoned pit in the lower part 

of the clay body was made into pottery in the mid-1920's (L. R. Laxson, resident 

Coleman Cut Rd., oral commun., 1966). 

Overburden: 0--6 ft of loessal silt; 0--20 ft of gravel and pebbly sand, lower few 

feet locally iron-cemented; 0-30 :ft of loose sand. Total overburden ranges from 

0 to 50 ft. 

Raw properties: Working properties, low plasticity; water of plasticity, 31.2 percent; drying shrinkage, 2.5 percent; dry strength, low; drying defects, none; 

pH, 5.9; not effervescent in HOI. 

Slow-firing tests: 

Percent Percent Bulk 

Temperature (°F) Color Hardness total absorption density shrinkage 

3 5. 0 38.9 1. 25 

3 5. 0 37.4 1. 29 

3 5. 0 34. 9 1. 32 

3 10. 0 25.4 1. 50 

5 10.0 23.2 1. 55 

5 12. 5 17." 3 1. 88 

1,800_ _ _ _ _ _ _ _ _ _ _ _ Cream __________ _ 1,900 _________________ do __________ _ 2,000 _________________ do __________ _ 2,100 ____________ Ivory ___________ _ 2,200 _________________ do __________ _ 

2,300 ____________ Gray ___________ _ 

Remarks: Low green strength; poor ceramic bond; high absorption at all temperatures; pyrometric cone equivalent 23. 

Bloating test: Negative. 

Potential use : Body component in artware and for stoneware or glazed structural tile mixtures. 
28 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

SAMPLE 20 

(USBM L·ab. No. 1652) 

Location and altitude: Natural exposure, 0.8 mile S. of Camelia, Heath 7lh-min 

quad., Kentucky (Olive, 1966) ; 445ft alt. 

Nearest railroad: 4.85 miles N. 

Stratigraphic posiUon : Claiborne Formation. 

Description of clay body : Exposed over a distance of 300 ft near bottom of 

narrow stream channel; 5 ft thick (determined by hand angering) near 

upstream end of exposure. 

Overburden: 1-3 ft of unconsolidated medium- to coarse-grained clayey sand, 

overlain by 4-10 ft of sandy gravel and gravelly silt. Overburden in upland 

areas adjacent to exposure may be as much as 30 ft thick. 

Raw properties: Long-working, smooth, plastic; water of plasticity, 25.8 percent; 

drying shrinkage, 0.6 percent; dry strength, fine; drying characteristics, good, 

scum ; pH, 7.32; color, white. 

Slow-firing test: 

Temperature ( F) Color Hardness 

1,800 _______ Pink white _____ Fairly hard __ _ 1,900 ____________ do ______________ do _____ _ 

2,000 _______ Yellow white ____ Hard _______ _ 2, 100 ___________ do _________ Very hard ___ _ 2,200 _______ Cream ______________ do _____ _ 2,300 ____________ do _________ Steel hard ___ _ 

Percent Percent 

linear absorption shrinkage 

4.5 

4.5 

4.5 

9.5 

9.5 

10.5 

4.5 

4.6 

4.9 

9.2 

12. 1 

19.3 

Approximate specific 

gravity 

2.58 

2.56 

2.58 

2.56 

2.54 

2.49 

Remarks: Yellow scum on surface; wavey surface; off-white color; high shrinkage; high absorption. Addition of BaCOa would remove scum. Either washing the clay or addition of a barium salt would remove the soluble salts in the clay and probably lower the absorption percentage in the firing. Addition of grog would reduce shrinkage. Pyrometric cone equivalent, 23-24. 

Bloating test : Negative. 

Other tests: Solu-Bridge K factor, 2.00 (causes yellow scum). 

Potential use: Low-duty refractory and sagger mix. A borderline clay between 

a kaolin (china) clay and a ball clay. 

SAMPLE 21 

(USBM Lab. No. 1665-E) 

Location and altitude: Natural exposure in the channel of Black Branch, 0.9 mile 

N. 17° E. of Camelia, Heath 7lh-min quad., Kentucky (Olive, 1967); 415ft alt. 

Nearest railroad: 3.25 miles N. 

Stratigraphic position: Claiborne Formation. 

Description of clay body : Exposed at intervals over a distance of 150 ft. Total 

thickness, not determined, but hand-auger hole near middle of outcrop area 

penetrated 11ft of clay without reaching base. 

Overburden: Alluvium that consists of 3--6ft of sandy gravel and gravelly sand, 

overlain by 6 ft of sandy silt. 

Raw properties: Long-working, smooth, plastic; water of plasticity, 31 percent; 

drying shrinkage, none ; dry strength, fine ; drying characteristics, fine ; pH, 

4.71; color, tan. 
PROPERTIES AND USE, UNDEVELOPED CLAY DEPOSITS 29 

Slow-firing test: 

Temperature eF) Color Hardness 

1,800 _________ Pale pink _____ Soft ________ _ 1,900 ______________ do _______ Fairly hard __ _ 2,000 ______________ do _______ Hard _______ -

2,100 _________ Cream _______ Very hard ___ _ 2,200 _________ Buff _________ Steel hard ___ _ 2,300 _________ Light gray _________ do ______ _ 

Percent 

linear 

shrinkage 

0.5 

. 5 

5.0 

10.0 

14.0 

14.0 

Percent 

absorption 

4.0 

4. 1 

4.6 

7.7 

15.1 

53.7 

Approxi- mate 

specific 

gravity 

2.55 

2.61 

2.59 

2.60 

2.54 

2.43 

Remarks: Shrinkage, a little high; high absorption, slightly higher than sample 20; qua~tz, too fine to remove effectively. Addition of grog would reduce shrinkage. Pyrometric cone eqmvalent, 25-26. 

Bloating test: Negative. 

Other tests: Solu-Bridge K factor, 0.45. 

Potential use: Doubtful low-duty refractory clay (shrinkage too high) ; fair ball 

clay ; art pottery clay. 

SAMPLE 23 

(USBM Lab. No. K-8-4) 

Location and altitude: Natural exposure in west-flowing tributary of Caney 

Branch, 1.9 miles E. of Mount Olive Church, Kirksey 7"Jh-min quad., Kentucky 

(Wilshire, 1963) ; 470ft alt. 

Nearest railroad : 8.3 miles E. 

Stratigraphic position: Wilcox Formation. 

Description of clay body : Thickness, not determined; 2--5 ft of dark-gray to 

black clay exposed over a distance of 300ft, between altitudes 460 and 475ft, 

in tributary of Caney Branch, and over a distance of 250 ft in a smaller channel 

that enters the tributary from the north. Clay intergrades with thinly laminated sand and clay at lower end of exposure and is concealed by alluvium 

at upper ends. 

Overburden : 4-8 ft of alluvial silt in valley bottom and possibly as much as 35 

ft of gravel and 15ft of silt in adjacent upland areas. 

Raw properties: Low plasticity ; water of plasticity, 34.2 percent; drying defects. 

none ; drying shrinkage, 2.5 percent ; dry strength, low; pH, 4.4 ; color, gray ; 

not effervescent in HCl. 

Slow-firing test: 

Temperature ( F) Color 

1,800 _____________ Cream __________ _ 1,900 __________________ do __________ _ 2,000 __________________ do __________ _ 

2,100 _____________ Ivory ___________ _ 2,200 __________________ do __________ _ 

2,300 _____________ Gray----- _______ _ 

Percent Percent Bulk 

Hardness tot<tl absorption density 

2 

2 

3 

6 

6 

6 

shrinkage 

2. 5 

2. 5 

5. 0 

10. 0 

10. 0 

15. 0 

32.0 

30.0 

26. 8 

17. 2 

15. 9 

6. 1 

1. 43 

1. 48 

1. 56 

1. 72 

1. 85 

2. 11 

Remarks: Low green strength; poor ceramic bond at firing temperatures below 2,100° F.; pyrometric cone equivalent, 20. 

Bloating test: Negative. 

Potential use: Body component in artware and for stoneware or glazed structural 

tile mixtures. 
30 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

SAMPLE 2'Tb 

(USBM Lab. No. 1665-B) 

Location and altitude: Auger hole about 3 miles SSW. of Paducah, Paducah West 

7%-min quad., Kentucky (Finch, 1966) ; 424--429 ft alt. 

Nearest railroad: About 3 miles E. of drill hole. 

Stratigraphic position: Wilcox Formation. 

Description of clay body: Penetrated in auger hole from 416 to 449ft alt; underlain by dark-gray sandy clay to 391 ft alt; day crops out in floor of creek 1,400 

ft to south, at 415 :fit alt. 

Overburden: At auger hole, 12ft of loess and gravel. 

Raw properties: Dong-working, sm·ooth, plastic; water of plasticity, 41.0 percent; 

drying shrinkage, 5.0 percent ; dry strength, fine ; drying characteristics, good, 

slight scum; pH, 7.30; color, gray. 

Slow-firing test: 

Temperature (oF) Color Hardness 

1,800 _________ Pale tan ______ Soft ________ _ 1,900 ______________ do _______ Fairly hard __ _ 2,000 _________ Tan _________ Hard _______ _ 2, 100 _________ Brown ____________ do ______ _ 

2,200 _________ Gray brown ___ Very hard ___ _ 2,300 _________ Gray ________ Steel hard ___ _ 

Percent 

linear 

shrinkage 

6.0 

6.0 

11.0 

15.0 

18.5 

18.5 

Percent 

absorption 

3.3 

3.8 

5.9 

9.5 

27.5 

74.6 

Remarks: Fair color; high shrinkage; very high absorption; slight scum on surface. 

Approximate specific 

gravity 

2.49 

2.45 

2.42 

2.39 

2.30 

2.25 

Preliminary bloating test: Crushing characteristic, good; particle size, -%. inch 

+ 1h inch ; retention time, 15 min. 

Temperature (° F) Bulk Lb per Percent 

density cu ft absorption 

1,900 ___________ 2. 28 142 9. 7 

2, 000_--------- 1. 92 120 7. 8 2,100 ___________ 1. 50 93 5. 9 2,200 ___________ . 96 60 7. 4 

Observation: Good lightweight aggregate possibilities. 

Other tests: Solu-Bridge K factor, 5.20. 

Potential use : Art pottery,- after being washed. 

Remarks 

Very slight expansion. 

Slight expansion. 

Fair expansion, fair skin. 

Good expansion, good skin. 

SAMPLE 27c 

(USBM Lab. No. 1665-C) 

Location and altitude: From same ·auger hole as S.ample 27b, at the interval of 

419-424 ft alt. 

Stratigraphic position: Wilcox Formation. 

Raw properties: Long-working, smooth, plastic; water of plasticity, 45.2 percent; 

drying 'shrinkage, 5.0 percent; dry strength, good; drying characteristics, fair, 

slight warping, scumming, slightly rough; pH. 6.88; color, gray. 
PROPERTIES AND USE, UNDEVELOPED CLAY DEPOSITS 31 

Slow-firing test: 

Temperature (oF) Color Hardness 

Percent Percent 

linear absorption shrinkage 

Approximate specific 

gravity 

1,800 _________ Pale tan ______ Fairly hard __ _ 1,900 ______________ do ____________ do ______ _ 

2,000 _________ Tan _________ Hard _______ _ 2, 100 _________ Brown ____________ do ______ _ 

2,200 _________ Gray brown ___ Very hard ___ _ 2,300 _________ Gray ________ Steel hard ___ _ 

6.0 

7.5 

14.0 

14.0 

16.0 

19.0 

Remarks: Fair color; high shrinkage; slightly high absorption; surface scum. 

2.6 

2.8 

4.3 

4.5 

10. 1 

20.8 

2.45 

2.41 

2.34 

2.36 

2.26 

2.21 

Preliminary bloating test: Crushing characteristic, fair ; particle size, -%, inch 

+ lh inch; retention time, 15 min. 

Temperature Bulk Lbper Percent Remarks 

eF> density cu. ft absorption 

1,900 _____ ------ 2.37 148 8. 1 Slight expansion. 2,000 ___________ 2.34 146 6.5 Do. 2,100 ___________ 1. 70 106 7.4 Fair expa,nsion. 2,200 ___________ 1. 60 100 6.7 Fair expansion, fair skin. 

Observation: A little heavy for lightweight aggregate material. 

Other tests: S'olu-Bridge K factor, 5.60. 

Potential use : Art pottery, after being washed. 

SAMPLE 28a 

(USBM Lab. No. X-1-3) 

Location and altitude: Natural exposure, 1.45 miles WNW. of Oak Level, Oak 

Level 7:1h-min quad., Kentucky (Olive and Davis, 1968); 430ft alt. 

Nearest railroad : 4.3 miles NE. 

Stratigraphic position: Wilrox Formation, overlain unconformably by Olaiborne 

Formation. 

Description of clay body: Uppermost 1-3ft exposed over a distance of 300ft along 

the channel of Riley Branch ; tortal thickness, not determined. 

Overburden: 3-6ft of alluvial silt and gravel beneath flood plain CYf Riley Branch, 

and possibly as much as 10ft of sand, 20ft of gravel, and 5 ft of silt in upland 

areas. 

Raw properties: Moderately plastic; water of plasticity, 25.8 percent; drying 

shrinkage, 2.5 percent; dry strength, good; drying defects, none; color, tan. 

Slow-firing test: 

Percent Percent Bulk 

Temperature (°F) Color Hardness total absorption density 

1,800 _____________ Tan ____________ _ 1,900 __________________ do __________ _ 

2,000 _____________ Light brown _____ _ 2,100 _____________ Dark brown _____ _ 

shrinkage 

2 5. 0 

3 7. 5 

4 12. 5 

6 Expanded 

15. 1 

10. 2 

.8 

1. 80 

1. 97 

2. 30 

2,200 _____________ ~elted __________________________________________ _ 2,300 __________________ do __________________________________________ _ 

Remarks: Color, marginal for face brick; short firing range. 
32 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

Bloating test: Particle size, -% inch +lh inch; retention time, 15 min. 

Teml?erature 

(F) 

1,900 _________________________ _ 

~ooo_ ------------------------ ~ 100-------------------------- 2,200 _________________ ·-

Observation: Not a good bloating clay. 

Potential use: Structural tile. 

Bulk 

density 

1. 70 

1. 83 

1. 67 

. 98 

Lb per Percent 

cuft absorption 

106 20.6 

114 12.9 

104 4.5 

61 5.3 

SUMMARY AND CONCLUSIONS 

Remarks 

Melted. 

A comparison of the mineralogy of the clay-mineral fraction of al1 

samples analyzed by X-ray diffraction reveals significant differences 

in the percentages of kaolinite, illite, montmorillonite, and mixedlayer-clay minerals as related to stratigraphic position. Kaolinite content is greater than 60 percent of the clay-mineral fraotion in all 11 

Claiborne samples, in four of seven Wilcox samples, and in four of 16 

Jackson samples (table 3). Illite, though present in most samples frmn 

all formations, is least prevalent in samples from the Jackson Formation and is most abundant, as much as 43 percent, in samples from the 

'Vilcox Formation. Montmorillonite account8 for 14 to 78 percent of 

the clay-mineral fraction in 13 samples from the Jackson Formation 

and is an uncommon constituent in samples from the Wilcox and Claihorne Formations. Mixed-layer clay is present in most samples studied, 

but largest percentages occur in those from the Jackson Formation. 

Six samples from the Jackson contain more than 25 percent mixedlayer clay. 

Clay bodies of the Claiborne and Wilcox Formations generally contain large amounts of kaolinite and little or no montmorillonite and 

have greater potential as sources of commercial-grade clay than do 

those of the Jackson Formation, which generally contain montmorillonite in excess of 10 percent (fig. 3) . 

Mineralogic and size ·analyses and ceramic tests indicate that undeveloped clay bodies from various parts of the Jackson Purchase 

1egion and from different parts of the stratigraphic section have potential value for use in ceramics. Of clay bodies studied, those with the 

desirable characteristics of fine texture, high kaolinite and low quartz 

contents, and with little or no montmorillonite are represented by 

samples 19, 20, and 21 (table 3), all from the Claiborne Formation, 

and possibly sample 23 (table 3) from the Wilcox Formation. Other 

undeveloped clay bodies probably are not suited for use in fine ceramics 

because of their mineralogic composition or because they are too coars~ 
SUMMARY AND CONCLUSIONS 

ILLITE+MIXED-LAYER CLAY +CHLORITE(IMC) 

10 20 

MONTMORILLONITE 

30 40 50 60 

EXPLANATION 

• Jackson Formation 

• Claiborne Formation 

... Wilcox Formation 

70 

Circled symbol is clay-pit sample 

Number of samples indicated by 

italic number where more than one 

80 

33 

90 

KAOLINITE 

FIGURE 3.-Clay mineralogy of samples from Eocene clay deposits (based on 

analyses given in table 3). 

grained; however, they have potential for use in the manufacture of 

stoneware, pottery, artware, brick, and structural tile. 

Sample 23 has the finest particles of all samples analyzed for size 

distribution (table 4) . More than 76 percent of the sample is made 

up of particles less than 0.002 mm; 81.4 percent is less than 0.004 mm. 

The clay-mineral fraction contains 43 percent illite (table 3), which 

far exceeds that in samples from commercially exploited clay bodies 

in the area. The percentages of kaolinite, IMC, and quartz are within 

ranges found by Holdridge (1963) in second-quality ball clays and 

stoneware clays (tables 5, 6); however, the lime content is probably 

higher than in ball clays studied by Holdridge. 
34 CLAY DEPOSITS, EOCENE AGE, KENTUCKY AND TENNESSEE 

About one-third the "sawdust sand" of samples 24 and 26 (table 3) 

is composed of clay, of which more than 80 percent is kaolinite. Deposits 

of "sawdust sand" in the Wilcox Formation are large and extensive and, 

if beneficiated, may 'Prove valuable as sources of high-grade ceramic 

clay. Much additional investigative work involving detailed drilling, 

sampling, and ceramic testing will be needed to prove adequate reserves 

of clay that have uniform mineralogic composition and ceramic 

properties. 

REFERENCES CITED 

Blade, L. V., 1965, Geologic map of the Hickory quadrangle, Graves County, 

Kentucky: U.S. Geol. Survey Geol. Quad. Map GQ-457. 

Bouyoucos, G. J., 1936, Directions for making mechanical analyses of soils by the 

hydrometer method : Soil Sci., v. 42, p. 225-229. 

Easton, H. D., 1913, Report on the technology of Kentucky clays, including chemical and mechanical analyses, and burning tests: Kentucky Geol. Survey, ser. 

4, v. 1, p. 713-888. 

Finch, W. I., 1963, Geology of the Water Valley quadrangle in Kentucky: U.S. 

Geol. S'urvey Geol. Quad. Map GQ-269. 

---1964, Geology of the Symsonia quadrangle, Kentucky: U.S. Geol. Survey 

Geol. Quad. Map GQ-326. 

---1965, Geology of the Mayfield quadrangle, Graves County, Kentucky: U.S. 

Geol. Survey Geol. Quad. Map GQ-372. 

---1966, Geologic map of the Paducah Wesrt and part of the Metropolis 

quadrangles, Kentucky-Illinois: U.S. Geol. Survey Geol. Quad. Map GQ-557. 

---1968, Geologic map of the Lovelaceville quadrangle, western Kentucky : 

U.S. Geol. Survey Geol. Quad. Map GQ-763. 

Finch, W. I., and Minard, J.P., 1966, Geologic map of the Farmington quadrangle, 

Graves County, Kentucky: U.S. Geol. Survey Geol. Quad. Map GQ-530. 

Floyd, R. J., and Kendall, T. A., 1955, Miscellaneous clay and shale analyses for 

1952-54: Kentucky (!eol. Survey, ser. 9, Rept. Inv. 9, 61 p. 

Gildersleeve, Benjamin, 1945, Mineral resources [of the Jackson Purchase region, 

Kentucky]: Kentucky Dept. Mines and Minerals, ser. 8, Geol. Div. Bull. 8, p. 

92-122. 

Grim, R. E., 1962, Applied clay mineralogy: New York, McGraw-Hill Book Co., 

Inc., 422 p. 

Holdridge, D. A., 1963, The composition of some British clays used in the fine 

ceramic industries, in Bradley, W. F., ed., Clays and Clay Minerals-proceedings of the Eleventh National Conference on Clays and Clay Minerals 

* * * Ottawa, Ontario, Canada, August 13-17, 1962: New York, MacmUian 

Oo., p. 351-364. 

Loughridge, R. H., 1888, Report on the geological and economic features of the 

Jackson's Purchase region, embracing the counties of Ballard, Calloway, 

Fulton, Graves, Hickman, McCracken, and Marshall: Frank:~ort, Ky., Kentucky Geol. Survey, 357 p. 

McGrain, Preston, and Kendall, T. A., 1957, Miscellaneous clay and shale analy,ses 

:flor 1955-1956: Kentucky Geol. Survey, ser. 9, Rept. Inv. 13, 70 p. 

McGrain, Preston, Kendall, T. A., and Teater, T. C., 1960, Miscellaneous clay and 

shale analyses for 1957-1959: Kentucky Geol. Survey, ser. 10, Retpt. Inv. 3, 

p. 4-57. 
REFERENCES CITED 35 

Merschat, C. E., and Larson, L. T., 1967, Mineralogy of certain West Tennessee 

clays [abs.]: Geol. Soc. America, Southeastern Sec. Ann. Mtg., Tallahassee, 

Fla. 1967, Program, p. 43. 

Olive, W. W., 1963, Geology of the Lynn Grove quadrangle in Kentucky: U.S. 

Geol. Survey Geol. Quad. Map GQ-268. 

---1966, Geologic map of the Heath quadrangle, McCracken and Ballard 

Counties, Kentucky: U.S. Geol. Survey Geol. Quad. Map GQ-561. 

---1967, Geologic map of part of the Cayce quadrangle, Hickman and Fulton 

Counties, Kentucky: U.S. Geol. Survey Geol. Quad. Map GQ-601. 

Olive, W. W., and Davis, R. W., 1968, Geologic map of the Oak Level quadrangle, 

Marshall and Graves Counties, Kentucky: U.S. Geol. Survey Geol. Quad. 

Map GQ-744. 

Parker, T. W., Warren, I. H., and Morcom, A. J., 1951, Estimation of montmorillonite in china clay: Clay Minerals Bull., v. 1, no. 6, p. 166--168. 

Pryor, W. A., and Glass, H. D., 1961, Cretaceous-Tertiary clay mineralogy of the 

Upper Mississippi embayment: Jour. Sed. Petrology, v. 31, p. 38-51. 

Ross, C. S., and Kerr, P. F., 1931, The kaolin minerals: U.S. Geol. Survey Prof. 

Paper 165-E, p. 151-176. 

Schultz, L. G., 1964, Quantitative interpretation of mineralogic composition from 

X-ray and chemical data for the Pierre Shale: U.S. Geol. Survey Prof. Paper 

391-C, p. C1-C31. 

Smoot, T. W., 1963, Clay minerals in the ceramic industries, in Swineford, Ada, 

ed., .Clays and clay minerals-proceedings of the Tenth National Conference 

on Clays and Clay Minerals, Austin, Texa•s, Oct. 14-18, 1961: New York, Pergamon Press, p. 309-317. 

Swanson, R. W., and Wilshire, H. G., 1967, Geologic map of the Westplains quadrangle, Graves County, Kentucky: U.S. Geol. Survey Geol. Quad. Map 

GQ-587. 

Tschudy, R. H., 1965a, Palynological investigations in the Upper Cretaceous and 

Tertiary of the Mississippi embayment region-1: U.S. Geol. Survey openfile rept., 59 p. 

---1965b, Palynological investigations in the Upper Cretaceous and Tertiary 

of the Mississippi embayment region-2: U.S. Geol. Survey open-file rept., 

19 p. 

---1966, Palynological inve~igations in the Upper Cretaceous and Tertiary of 

the Mississippi embayment region-3: U.S. Geol. Survey open-file rept., 15 p. 

---1967, Palynological investigations in the Upper Cretaceous and Tertiary of 

the Mississippi embayment region-4: U.S. Geol. Survey open-file rept., 48 p. 

U.S. Bureau Mines, 1943-61, Minerals yearbooks 1942-60: Washington, D.C., U.S. 

Govt. Printing Office. 

Walker, F. H., 1953, Miscellaneous clay and shale analyses for the year 19•51-52: 

Kentucky Geol. Survey, ser. 9, Rept. Inv. 6, 32 p. 

Whi,tlatch, G. I., 1940, The clays of West Tennessee: Tennessee Div. Geology Bull. 

49,368 p. 

Wilshire, H. G., 1963, Geology of the Kirksey quadrangle, Kentucky: U.S. Geol. 

Survey Geol. Quad. Map GQ-246. 

0