Chattanooga Shaleand Related Rocksof Central Tennessee
and Nearby Areas
GEOLOGICALSURVEYPROFESSIONAL

This report concerns work done on behalfof the U.S. Atomic Energy Commission
and is published with the permission of
the Commission

PAPER

357

Chattanooga Shaleand Related Rocksof Central Tennessee
and Nearby Areas
By LOUIS C. CONANT and VERNON E. SWANSONGEOLOGICALSURVEYPROFESSIONAL

PAPER

357

"It is the geologist's plane of reference^ as well as puzzle" Safford(l86c}}.
Ihis report concerns work done on behalfof the U.S. Atomic Energy Commission
and is published with the permission of
the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1961

UNITED STATES DEPARTMENT OF THE INTERIORSTEWART L. UDALL Secretary
GEOLOGICAL SURVEY
Thomas B. Nolan, Director

The U.S.

Geological

Surveyhas cataloged this publication as follows:

Conant, Louis Cowles, 1902Chattanooga shale and related rocks of central Tennessee
and nearby areas, by Louis C. Conant and Yernon E. Swanson. Washington, U.S. Govt. Print. Off., 1961.
v, 91 p. maps, diagrs., tables. 30 cm.
Professional paper 357)

(U.S. Geological Survey.

Part of illustrative matter in pocket.
Bibliography: p. 85-88.
1. Shale Tennessee. 2. Geology Tennessee-Chattanooga area.
I. Swanson, Vernon Emanuel, 1922joint author. II. Title: Chattanooga shale.
(Series)

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

Washington 25, D.C.

CONTENTS
Abstract __________________
Introduction. _______________
Location and general relations.
Fieldwork__ _ ______________
Acknowledgments. ___________
Terminology. _______________
Rock terms.____________
Color terms_____________
Linear measurements___
Sample numbering. ______
Surface features_____________
General geology.____________
Regional stratigraphy. ___Regional structure. _________________________
Cryptoexplosive (cryptovolcanic) structural features in Tennessee________________________
Flynn Creek feature ___ ________________
Chattanooga shale. _________________________________
History of the name_ _ _________________________
Pre-Chattanooga surface _ ______________________
General character_________ __________________
Sub-Chattanooga residuum. _________________
Age_
____
______________
Historical summary. ________________________
Fossils __ _________________________________
Plant matter. __________________________
Conodonts _____________________________
Other fossils __ _________
Present views _______________
Stratigraphy. ___________________Classifications. _ ____ _ ______
Suggested standard locality. __Basal sandstone. ____________
Hardin sandstone member____
Dowelltown member. ____ _ _Lithologic character. _____
Extent and thickness _ __Lower and upper contacts
Lower unit __ __________
Upper unit _ ___________
Gassaway member. __________
Lithologic character ___Extent and thickness_____
Lower and upper contacts
Basis for subdivision. ____
Lower unit _ ___________
Middle unit _ __________
Upper unit __ __________
Distribution ___ ________ __ ____

Page
1
2
3
4
5
5
5
6
6
6
6

10
12
12
13
13
14
16
16
19
19
19
20
21
21
21
21
23
23
25
28
28
28
29
29
30
34
34
35
36
36
36
39
40
40

Chattanooga shale Continued
Composition _________________
Chemical determinations
Petrographic determinations
Quartz ___________________
Mica_ ____________________
Feldspar__ __________________________
Pyrite and marcasite_ ________________
Phosphate. _________________________
Plant matter. _______________________
Other constituents ___________________
Paleogeography during Late Devonian time_
Regional tectonic influence _________
Geosyncline_______ _______ _______
Landmass ___ _ _________________
Interior platform. _______________
Extent of the Chattanooga sea ________
Sources____ _________-___-_-_-____-----_-__.
Transportation. _ ___________________________
Rate of accumulation. ______________________
Compaction. _______________________________
Relation of black shale to gray claystone_____.
Environment of deposition_____________________.
General considerations..-- _ __________________
Previous views __.._______________---_______.
Indications of deep-water origin of the shale. _.
Indications of shallow-water origin of the shale.
Maury formation ___________________________________
History of the name __ _________________________
Suggested standard locality. _____________________
General description. ____________________________
Phosphate nodules. _____________________________
Extent and thickness__________-________-_______Age and fossils _________________________________
Lower and upper contacts. ______________________
Significance. ___________________________________
Economic geology____ _ ______________________________
Light-weight aggregate. _________________________
Oil shale__ _ ____________________________________
Phosphate. ____________________________________
Pigment. _ _____________________________________
Sulfuric acid_ __________________________________Uranium __ ___________________________________
Sampling. _________________________________
Determination __ _ _________________________
Relations __________________________________
Origin and distribution_______________-_____.
Regional variations in content _ ______________
Tonnage__ _ ________________________________
Locality register. ___________________________________
Selected references. _________________________________
Index___ _________ ____--________-_________----_____.

m

Page
42
43
43
45
46
46
46
46
47
47
48
48
48
51
51
51
51
52
52
54
54
55
55
56
56
57
59
60
62
63
63
63
65
66
67
67
68
69
69
69
70
70
70
70
70
71
71
71
75
76
77
85
89

IV

CONTENTSILLUSTRATIONS[Plates 1, 3, 7,8,12,14,15, and 17 in pocket]

Page
PLATE 1. Outcrops of the Chattanooga shale and of the Maury formation in central Tennessee and nearby areas.
2. Falls of Fall Creek. _____________________________________________________ Faces 2
3. Sub-Chattanooga geologic map of central Tennessee.
4. A, Basal part of the Fort Payne chert. B, Folded and crumpled beds of the upper (Gassaway) member of the
Chattanooga shale on east side of the Sequatchie Valley. C, Gentle syncline in the Eastern Highland Rim
area. D, Dipping beds of Chattanooga shale on sloping side of the Flynn Creek cryptoexplosive feature Faces 18
5. A, Angular unconformity of about 4° at base of Chattanooga shale, west of Nashville, Tenn. B, Sub-Chattanooga residuum near Pulaski, Giles County, Tenn. C, Photomicrograph of a Tasmanites spore in grayclaystone of the upper unit of the Dowelltown member of the Chattanooga shale ________ Follows 18
6. A, Massive black shale of the Gassaway member overhanging shale of the Dowelltown member. B, Characteristic outcrop of the Chattanooga shale in De Kalb County, Tenn________________________________ Follows 18
7. Fence diagram showing relations of the several units of the Chattanooga shale and of the Maury formation.
8. Thickness of the Dowelltown member of the Chattanooga shale.
9. A, Massive shale of the Gassaway member overhanging the weaker beds of the upper unit of the Dowelltown
member. B, Gray claystone and black shale beds of the upper unit of the Dowelltown member. C, Center
Hill bentonite bed in upper unit of the Dowelltown member. D, Minute laminae of siltstone in sawed
block of massive black shale of the Gassaway member ______________________ ______________ __ Faces 19
10. A, Massive black shale of the Gassaway member in contrast with the friable shale of the Dowelltown member.
B, Typical outcrop of weathered Chattanooga shale in road cut______________________________________
34
11. A, B, Photomicrographs of black shale of the upper unit of the Gassaway member showing regularity of thelamination ___________________________________________________________________ Follows 34
12. Thickness of the Gassaway member of the Chattanooga shale.
13. A, "Varved" bed at base of middle unit of the Gassaway member. B, Maury formation between the Fort
Payne chert and the Chattanooga shale. C, Maury formation.____________ _________ Follows 34
14. Approximate regional distribution of Upper Devonian and Lower Mississippian black shale and related rocks
in the United States.
15. Thickness of the Chattanooga shale, exclusive of the Hardin sandstone member.
16. A, Standard section of the Maury formation. B, Phosphate nodule bed at base of the Maury formation. C,
Contact between Fort Payne chert and Maury formation._______________________________________ Faces 35
17. Graphs showing oil yield of the Chattanooga shale.
FIGTTBE 1. Index map of area in which the Chattanooga shale and the Maury formation were studied in detail._____3
2. Chief physiographic features of central Tennessee and nearby areas _______________________________________
7
3. Cross section of the Flynn Creek cryptoexplosive feature._______________________________________________
10
4. Map and cross section of the Swan Creek area of Tennessee showing the gradual thickening of the black shale
unit of the Chattanooga shale seaward from a large island-______________________________
15
5. Standard section of the Chattanooga shale_____________-______----_--_-----_-----_---------__------_--_
24
6. Thickness and distribution of the Hardin sandstone member.____________________________________________
26
7. Map showing distribution of the Center Hill bentonite bed in central Tennessee_____________________________
32
8. Map of outcrops that show the thinning of the upper unit of the Dowelltown member_____________________
34
9. Cross section along an east-west line of diamond-drill holes that passes 2 miles south of Smithville, Tenn______
37
10. Cross section along an east-west line of diamond-drill holes that passes 3 miles south of Smithville _________
38
11. Correlation of units of the Chattanooga shale in northern Tennessee and southern Kentucky_ __ ______
39
12. Block diagram showing generalized interpretation of Late Devonian paleogeography and the stratigraphic
relations of the sediments_____________________________________________________________ ____49
13. Map outlining paleotectonic and paleogeographic features in the United States near the end of the Devonian.__50
14. Chart showing standard section of the Maury formation_____________________-_-_________________________
64
15. Apparent interfingering of the Maury formation and the Chattanooga shale._______________________________
65
16. Localities of drill holes in Chattanooga shale-_----____---__---____-_--___-______-__-____-__-___-_____
72
17. Localities of drill holes near Smithville, Tenn_________________________________________________________
73
18. Gamma-ray log of the Chattanooga shale and the Maury formation_____________________________________
74

CONTENTS

V

TABLESTABLE 1. System for numbering stratigraphic samples_____-__--_----_---------------_--------------------------2. Comparison of stratigraphic nomenclature and age assignments of Campbell and of this report._______-__--__
3. Thickness data on the Dowelltown member, eastern edge of the Nashville Basin___________--___-__----_-4. Thicknesses of units at selected outcrops where the Bransford sandstone bed is present._____________________
5. Chemical analyses of outcrop samples of Chattanooga shale in Tennessee_________-.-_---_-----_-_--_--_---6. Chemical composition of shales and graywackes._______________________________________________________
7. Mineralogic composition of the more uraniferous parts of the black shale____________-_-------____-_----_-_
8. Clay content of Chattanooga shale_____________________________-_-_-_--_--_-------_-----_---_--.----_
9. Analysis of vitrain from the Chattanooga shale___________________________-___-__-__--_-__-_-_-___-_-_
10. Phosphate content of nodules from the Chattanooga shale and the Maury formation._______________________
11. Average thickness and uranium content of the lithologic units of the Chattanooga shale on the Eastern Highland Rim, between DeKalb and Coffee Counties, Tenn-_________________________-------_____________
12. Thickness and uranium content' of samples of the Gassaway member from the more eastern drill holes comparedwith the average from holes on the Eastern Highland Rim_______-_-----____------------_-----------_
13. Localities of outcrops shown on maps accompanying this report._____-____--_-_--_----------_-----------14. Correlation of locality numbers_______-_________-___-_-________--------___--------_-----------_-----

Page
6
22
34
35
43
43
43
46
47
70
71
75
77
84

CHATTANOOGA SHALE AND RELATED ROCKS OF CENTRAL TENNESSEE AND
NEARBY AREAS
By Louis C. CONANT and VEENON E. SWANSONABSTRACTThe Chattanooga shale and Maury formation, which have a
combined thickness of about 35 feet, crop out on the steep
slope between the Nashville Basin and the surrounding Highland Rim; outside the basin they are exposed in several rivervalleys and in folded areas. Throughout most of the areastudied these rocks are nearly flat lying, but in the southeasternpart they have been involved in the Appalachian folding andare commonly contorted and sheared.
The Chattanooga shale, now considered to be of Late Devonian age, lies unconfonnably on many formations ranging in age
from Middle Ordovician to Middle Devonian. It is overlain,with probable local disconformity, by the Maury formation,
chiefly of Mississippian age, which is overlain conformably by
the Fort Payne chert and related rocks. Hass' studies of theconodonts established the ages of the Chattanooga and theMaury, and other studies of bones and plant remains haveverified his findings concerning the age of the Chattanooga.
The following stratigraphic classification is used in thisreport:Maury formation.
Chattanooga shale:
Gassaway member:
Upper, middle, and lower units recognized; locallythe Bransford sandstone bed is at the base.
Dowelltown member:
Upper and lower units recognized; the Center Hillbentonite bed is in the upper unit.
Hardin sandstone member (present locally only).
Standard localities in DeKalb and Williamson Counties,
Term., for the Chattanooga shale and the Maury formation,
respectively, are proposed.
The Hardin sandstone member is a quartzitic, slightly phosphatic, virtually unfossiliferous unit present only in the southwestern part of the area studied. In a complete section theHardin grades upward into black shale of the Dowelltown
member, but locally it is overlain abruptly by black shale of the
Gassaway member, and in a few places by the Maury formation.
These relations suggest a short erosion interval at the end of
Dowelltown time and either a local absence of sedimentation
during Gassaway time or another interval of local erosion after
Gassaway time.
A thin sandstone that is present nearly everywhere at thebase of the Chattanooga shale has commonly been called theHardin sandstone, but such usage is unwarranted as the sandstone is quite unlike the Hardin in both lithologic character andage. The basal sandstone of the Chattanooga, commonly aninch or less thick, ranges in age from earliest Late Devonian toearliest Mississippian, depending on the time that the sea firstinundated an area. In the Swan Creek phosphate area the "bluephosphate" is an unusually thick and phosphatic manifestationof the basal sandstone of late Chattanooga and probably evenof early Maury age.

The Dowelltown member has a pronounced two-fold divisioneast of the Nashville Basin: the lower unit is chiefly blackshale, the upper unit is alternating gray claystone and blackshale. The lower shale unit commonly has a less massive
appearance than the shale of the Gassaway member. Black
shale lies immediately above the basal sandstone, locally isinterbedded with the sandstone, or in some places lies directlyon the pre-Chattanooga rocks. The shale unit locally has manythin beds or films of fine sandstone.
The upper unit of the Dowelltown, because of its abundant
beds of gray claystone, is the most easily recognized subdivisionof the Chattanooga shale. Near the top is the distinctive Center
Hill bentonite bed, about 1 inch thick, that can be traced over awide area in east-central Tennessee. The gray beds probably
represent times when the stagnant sea was aerated sufficiently
to partially oxidize the organic matter over wide areas, whereas
the black shale results from reducing conditions in which sulfurous bottom water prevented oxidation of the organic matter.
The cause of these postulated aerations is unknown. Toward
the north the gray claystone beds diminish in number, thelowest beds disappearing first. No unconformity separates thelower and upper units of the Dowelltown, so the lowest graybeds are probably less widespread because the hypothetical supposed aerating agency did not at first extend as far northward
as it did later. A slight diastem seems to separate the Dowelltown from the overlying Gassaway member, at least locally.
The Dowelltown member is absent over much of the area westof the Nashville Basin. Where it is present in that area, thetwo lithologic subdivisions cannot be identified and the Dowelltown is a nearly massive unit of dark-gray shale having a thinbasal sandstone. The member is also not a recognizable lithologic unit south of Tennessee.
In part of the area the Gassaway member can be divided into
three units because of the presence of an inconspicuous middle
unit that contains a few thin beds of distinctive gray siltstone
and claystone. A sandstone at the base of the Gassaway along
the Northern Highland Rim is termed the Bransford sandstone
bed, an adaptation of usage by Campbell (1946). A unique"varved" bed marks the base of the middle unit but probably
does not represent annual layering. Except for the thin middle
unit, the entire Gassaway is a nearly homogeneous successionof extremely thin bedded and tough black shale that, whenunweathered, has a massive appearance. In the northern partof the area the upper unit of the member is thicker and in its
upper part consists of a phosphate nodule-bearing shale that isyounger than the upper part of the shale elsewhere.
The Chattanooga shale is part of a blanket of black shale
and other marine rocks that were deposited in a sea thatcovered large parts of North America in Late Devonian time.
In Tennessee this sea covered most of what is now the Nashville dome, but a few areas appear to have been islands during
Chattanooga time.
The black shale contains about 20 to 25 percent quartz, 25 toCHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

30 percent clay and mica, 10 percent feldspar, 10 to 15 percent
pyrite, 15 to 20 percent organic matter, and 5 percent miscellaneous constituents. Most of the quartz grains range in size
from that of clay to about 0.02 mm in greatest diameter. The
black shale is minutely and well laminated, and this lamination
causes the fissility of the rock upon weathering.
The gray claystone has, by contrast, a somewhat larger proportion of clay minerals, finer grained quartz and mica, only
scattered fine particles of organic matter and pyrite, and muchcoarser stratification.
A shallow-water origin for the Chattanooga shale is indicatedby several circumstances. By contrast, any deep-water hypothesis involves serious inconsistencies. The black mud thatformed the Chattanooga shale probably accumulated in water
100 feet deep or less; some apparently accumulated close to
shorelines in water only a few feet deep. The sediment isbelieved to have been transported by sea-bottom traction, by
suspension, and by wind. The water-borne part probably camefrom land areas far to the east and northeast and from islandand other land areas in and near central Tennessee. Sedimentation appears to have been phenomenally slow, 30 feet ofshale representing deposition during most of Late Devonian
time.
Repeated gentle agitation of the water by waves and currents
probably shifted the mud continuously, so that it was wellsorted and was spread smoothly over the bottom. The finelaminations, which are typically irregular and discontinuous,
are thought to result from this repeated reworking of the sediments over a long period of time. No varves representing annual or other regular cycles of deposition were recognized.
Locally the mud was slightly channeled, and in at least one
area more than a foot of sediment was stripped away by submarine planation.
The Flynn Creek cryptoexplosive structure, a small area ofhighly disturbed Ordovician rocks, is of especial interest
because an abnormal thickness of some 200 feet of Chattanooga
shale is present above the structure. Apparently a deep depression did not exist over this disturbed area at the beginning of
Chattanooga time, as supposed, but the area sank slowly as theblack mud accumulated; the subsiding basin was kept filled byblack mud that moved along the sea bottom for considerable
distances.
The Maury formation consists chiefly of green mudstone
or glauconitic sandstone and in most places has a conspicuous
bed of phosphate nodules at or near its base. In some areas
black shale is also present in the formation. The Maury iscommonly only about 1 to 4 feet thick and represents most of
Kinderhook (Early Mississippian) time. Its lower contact isfairly distinct at most places; its upper contact is commonly
abrupt where overlain by the Fort Payne chert but is gradational where overlain by the New Providence shale and its
equivalents. In spite of its well-defined contacts, little physicalevidence has been seen of any unconformity associated with
the Maury. The formation seems to represent a time of transition between the shallow black-mud sea of Late Devonian
time, and the more widespread, well-aerated, and presumably
deeper sea of Mississippian time.
The phosphate nodules are present chiefly as irregularly
shaped nodules, balls, and plates, most of which are concentrated
in a single layer and are embedded in black shale, glauconitic
sandstone, or claystone. The bed of nodules is a distinctive
feature of the Maury formation over most of the area and is
known to range in thickness from 1 inch to 2 feet within ahorizontal distance of 50 feet. The nodules seem to haveaccumulated at a time when clastic sedimentation had almost
ceased, as they appear to be doing in places on the ocean floor
today.
Economically the rocks of the Chattanooga shale and Maury
formation have thus far been of little importance. There areseveral possibilities for future utilization of the rocks, especially if the possible by-products are considered. The oilyield of the shale is about 10 gallons per ton, but this is much
below the yield of shales currently considered for oil extraction.
Other possible products that might be obtained are phosphate,
black pigment, sulfuric acid, uranium, and light-weight aggregate for concrete.
Each of the five stratigraphic units of the shale has a different uranium content, which varies only slightly over large
areas, but the three units of the Gassaway member are consistently the richest. For about 50 miles along the Eastern
Highland Rim, from DeKalb County to Coffee County, shale
approximately 15 feet thick contains an average of about 0.006
percent uranium, equivalent to about 1,800 tons of metallic
uranium per square mile. The grade normally decreases where
the thickness increases greatly or wherever the shale contains
phosphate nodules. The grade decreases northward into Kentucky, westward along the Northern Highland Rim, and southward into Alabama, Information from widely scattered places
suggests that the grade increases slightly eastward toward the
Sequatchie anticline where the uranium content appears to beslightly higher.
The uranium is thought to have been removed from the sea
water by plant particles on the sea bottom and the relativerichness to have resulted from the extremely slow sedimentation.
INTRODUCTION

The unusual properties of the black Chattanooga
shale have attracted the interest of geologists and laymen for fully 100 years, and both groups have studied
it in their diverse ways. The geologists, who have disagreed on the age, correlation, and origin of the rocks,
became embroiled in the well-known black shale controversy; the farmers and prospectors, lured by its
pyrite, coal-black color, and combustibility, have spent
untold effort and money trying to exploit its supposedmineral wealth.
The present investigation has shown that the Chattanooga shale is largely or entirely of Late Devonian
age and the Maury 1 formation of Early Mississippian(Kinderhook) age (Hass, 1956).
Some of the most picturesque and succinct statements
concerning the black shale in Tennessee were publishednearly a century ago by Safford (1869) in his "Geologyof Tennessee". Thus (p. 329):
Although comparatively very thin it is, on several accounts,
one of the most interesting formations in the State. It iswonderfully persistent, appearing in place, with rare exceptions,wherever its horizon is presented at the surface. * * * It is
the geologist's plane of reference, as well as puzzle, the wouldcounty in Tennessee from which the formation is named lapronounced "Murray," and geologists In the region use that pronunciation for the rock unit.

GEOLOGICAL SURVEY

PROFESSIONAL PAPER 357

PLATE 2FALLS OF FALL CREEKOne of the typical Highland Rim waterfalls over the Chattanooga shale. Crest of the main fall is formed by the basal 2 feet of the Fort Payne
chert. The Chattanooga shale extends downward to about the top of the dome-shaped cascade of the smaller fall at the right. Fort Payne
chert is in the upper part of the walls, limestone of Ordovician age in the lower part. Near locality 90. Reproduced from Safford (1869).

LOCATION AND GENERAL RELATIONS

be coal digger's ignis fatuus, a source of mineral waters, thealum and copperas maker's stock, an oil-schist and a pyroschist.

In his description of the shale, Safford (1869, p. 329)
gave the following account of one of its well-known
characteristics:
The presence of bituminous matter is also characteristic. The
shale generally contains so much of this as to be readily ignited,
and to burn for a while with considerable energy when in large
heaps, or when fragments of it are thrown upon glowing coals.
For this reason it is sometimes called a pyroschist. It does not,however, like stone coal, burn to ashes. The bulk, after burning,is the same as before, there being little else consumed beside asmall percentage of bituminous matter. It loses, however, itscolor, by the process, the mass becoming reddish gray. It is
often taken as an indication of stone coal, and, in Tennessee,
thousands of dollars, and a vast deal of enterprise, have been
wasted, in drifting into it.

The possibility of distilling oil from the black shales
has long been known (for example, Safford, 1869, p.
329) and has prompted several studies of the Chattanooga shale and its correlatives in the eastern UnitedStates. These investigations indicated that the eastern
black shales will yield at most about 15 to 20 gallons ofoil per ton (Grouse, 1925, p. 62; Miser, 1921, p. 147),
which is much less than the yield of black shales insome other areas. Our investigations showed that the
average oil yield of the richer upper half of the Chattanooga shale along the eastern edge of the NashvilleBasin is closer to 10 gallons per ton.
During the 1940's black shale in various parts of theworld was found to be notably radioactive (Russell, 1944, 1945; Beers and Goodman, 1944; Beers,
1945; McKelvey and Nelson, 1950) and to be a potential source of large quantities of uranium. Because theChattanooga shale, having about 0.004 to 0.008 percent
uranium, is one of the more radioactive shales in the
United States, the investigations reported here wereconducted by the U. S. Geological Survey at the request
and with the support of the Atomic Energy Commission. The chief aims were to make a thorough geologic
study of the shale and to obtain sufficient information
concerning the quantity and distribution of theuranium to evaluate the shale as a potential source ofuranium.
This report presents information on the stratigraphy, composition, structure, paleogeography, andorigin of the Chattanooga shale in central Tennessee
and nearby areas and describes its relationship to theunderlying and overlying formations.
LOCATION AND GENERAL RELATIONSIn Tennessee the Chattanooga shale crops out on thesteep slope between the Nashville Basin and the surrounding Highland Rim, and on many high hills with553638 612"ase map area~\ r- ;''^'' /..,^VIRGINIA r*\

FIGURE 1. Index map of area In which the Chattanooga shale andMaury formation were studied In detail.

in the basin. Outside the basin the black shale sequenceis exposed in several river valleys and around the large
Lexington Basin of Kentucky, Ohio, and Indiana. It
also crops out along the ridges and valleys of the folded
Appalachians in Tennessee, Georgia, and Alabama.
Figure 1 shows the general area of these studies.
Most of the outcrops examined in this study are inor near the Nashville Basin. Initially studies weremade on the eastern edge of the Nashville Basin, where
the Caney Fork has cut a deep re-entrant into theEastern Highland Rim, where road cuts and waterfalls
afford many excellent exposures of the Chattanooga
shale, and where previous reconnaissance studies had
indicated the Chattanooga might have its highest concentration of uranium. From the Caney Fork area theinvestigations were extended northward and southward and then around the entire basin; they included
many of the outliers within the basin. Other areas ofinvestigation in Tennessee were the Sequatchie Valley,
which is some 50 miles east of the Nashville Basin, andthe western valley of the Tennessee River and its eastern tributaries. To the south, scattered outcrops werestudied in northeastern Mississippi, northern Alabama,and northwestern Georgia. To the north, the shale was

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

studied and sampled in Kentucky in the valleys of theGreen and Cumberland Rivers, including the area now
inundated by the Wolf Creek Eeservoir.
Other field observations in northern Kentucky, Indiana, Ohio, southwestern Virginia, and eastern Tennessee have supplied background information of aid ininterpreting the geology of the main area of study.
FIELDWORK

Field investigations of the uranium in the Chattanooga shale were started by the Geological Survey
for the Manhattan Engineer District and were continued for its successor, the Atomic Energy Commission. In June 1944, A. L. Slaughter, S. E. Clabaugh,and W. H. Hass began a reconnaissance survey of the
Devonian and Lower Mississippian black shales of theeastern United States and found indications that theuranium content of the Chattanooga shale is higher
along the northern part of the Eastern Highland Kim
than at most other places. Additional reconnaissanceinvestigations in the eastern black shale areas by J. M.
Nelson, K. G. Brill, and A. P. Butler, Jr., consisted
chiefly of determining radioactivity and collecting
samples for uranium assays. In the course of his workon conodonts Hass also studied the Chattanooga
shale and the correlative rocks of several other partsof the eastern United States.
Field work on the present project was started late in1947 at the request of the Atomic Energy Commission
and was continued intermittently until 1955. For muchof the first year the chief effort was an intensive sampling program supplemented by a general geologic
study. Much of the later work was more largely of ageologic nature, but from time to time sampling programs were part of the study. In all, about 3,000
samples were taken from uranium analyses from about
250 outcrops, from about 75 drill cores, and from a 100foot adit (pi. 1, loc. 79). Geologic observations weremade on many other outcrops and on samples frommany exploratory oil wells. Plate 1 shows the outcropof the Chattanooga shale and about 250 numbered
localities from which most of the information used inthis report was obtained. Many drill hole locations areshown in figures 16 and 17.
Wherever samples were taken, measurements weremade of the several lithologic subdivisions of the Chattanooga shale (table 1, p. 6). In a few places, detailed
measurements were made of all obvious lithologic units
that are 0.01 foot or more thick and of some beds thatare even thinner; for each measured bed the color,fissility, and visible mineralogic characteristics werenoted. We also made observations concerning sedimentary structural features and types of contacts thatbound the formation and are within it. These detailed
observations permitted careful tracing throughout
large areas of some units heretofore unrecognized, andrevealed details that later helped explain the origin of
the shale. The Maury formation, which overlies theChattanooga shale throughout the area and has often
been considered a part of the shale, was studied in asimilar manner.
Samples were commonly taken at localities about 1 to
5 miles apart in the belief that they would reveal any
significant regional differences in uranium content, but
a few were taken at much closer spacing to test forpossible short-distance differences.
Hass studied the conodonts in about 325 samples
from 65 localities; he was the first worker to acquire
information adequate for determining the geologic ageof the black shale and related beds and for correlating
the lithologic units within the shale from one region toanother and from State to State. Detailed results ofHass' studies are presented in a separate report (1956).
Throughout its duration Conant was in generalcharge of the fieldwork for this project or was closely
associated with it. Swanson joined the project in 1949and conducted most of the investigations along theNorthern and Western Highland Kirns and in the morewestern areas in Tennessee.
Andrew Brown supervised a 1948 drilling program
and the driving of a 100-foot adit; he also had generalcharge of much of the sampling from 1947 to 1949. He
made many observations on the geology and later
helped materially in compiling data and assembling
geologic information.
B. C. Eobeck studied the stratigraphy, mapped, andsupervised the sampling in several areas from 1947 to1949. These areas included the Sequatchie Valley ofTennessee, that part of the eastern edge of the Nashville Basin from Cannon to Franklin Counties, much ofJackson and Clay Counties, that part of the Cumberland Kiver valley of Kentucky now inundated by the
Wolf Creek Eeservoir, and other scattered areas inTennessee and Kentucky.
K. E. Smith, who was with the project in 1947 and1948, was in charge of much of the early work in Putnam County and the northern part of DeKalb County.
T. M. Kelin, who was with the project from 1952 to
1954, spent 1953 on a cooperative drilling program conducted by the Geological Survey and Bureau of Minesfor the Atomic Energy Commission. He worked on
about 60 diamond-drill cores of the Chattanooga shale
and on local geologic problems.
Lynn Glover III worked for several months on the1953 drilling program and later spent about a year anda half studying the Chattanooga shale outcrops in the

TERMINOLOGY

folded area of southeastern Tennessee, northwestern
Georgia, and northeastern Alabama.
All the above men who do not share authorship contributed many observations and ideas that aided immeasurably in the formulation of this report, and tothem we owe much.
Others who had short assignments in the field, chiefly
to help in measuring and sampling outcrops, were
Chester E. Baker, Edward C. Berry, Wilfred J. Carr,John R. Houston, John E. Johnston, Charles Katlin,
John C. Reed, Jr., Lawrence E. Shirley, Julian Soren,
and Leon D. Willman.
ACKNOWLEDGMENTS

Many people and organizations contributed to thisstudy and it is impossible to name them all or to recall
the sources of all information and the origin of allideas. Several people and organizations, however, areespecially deserving of mention.
The financial support by the Division of Raw Materials, Atomic Energy Commission, made the project
possible. The cooperation and constant interest shownby technical personnel of that agency contributed muchto the study. Especial interest was shown by Messrs.
John Ruck and James Barr.
The Nashville District of the Corps of Engineers,
U. S. Army, supplied many maps of its reservoirs, gave
access to construction areas and drill cores, and permitted much work on land under its custody.
The Tennessee Division of Geology supplied manymaps and publications and gave free access to its large
file of well records and cuttings. Mr. H. B. Burwell,State Geologist during the early part of these studies,and Mr. H. C. Milhous were generous of their time andinformation. Mr. H. W. Ferguson and Mr. W. D.
Hardeman, who succeeded Mr. Burwell as State Geo" ogists, continued that friendly cooperation.
The Kentucky Geological Survey also supplied manymaps and publications. Dr. A. C. McFarlan, the ] )irector, and Mr. D. J. Jones, the State Geologist, followed the work with interest and cooperated wheneverrequested. Mr. Jones accompanied Robeck for several
days in the field to show him outcrops that seemedworthy of investigation.
The Tennessee Valley Authority drove a 100-footadit near the Sligo bridge, about 7 miles east of Smit hville, Tenn., after two invitations had failed to g;etprivate contractors to bid on the work. The TVA a' so
permitted access to its New Johnsonville steam plantsite when the foundation excavation afforded excellent
exposures of the Chattanooga shale.
The Post Office Department supplied the projectwith working and storage space at Sparta, Tenn.

The Magnolia Petroleum Co. obtained and turned
over to the Geological Survey core samples of the Chattanooga shale from its W. H. Patterson 1 cable-toolwell at Gruetli, Grundy County, Tenn.
The U.S. Bureau of Mines in 1953 took 71 diamonddrill cores of the Chattanooga shale for the Atomic
Energy Commission, enlarged the Sligo adit, and madevarious engineering studies of the shale. Mr. Robert T.
Hickman, in charge of the drilling, and Mr. Paul
Russell, in charge of the engineering work, were mostcooperative at all times. The drilling supplied excellent
cores for study and assay by the U.S. Geological Survey and other organizations.
Several members of a University of Tennessee party
that studied the shale for the Division of Research of
the Atomic Energy Commission during the later stagesof our studies were in the field several times with members of our project. Their presence, especially that of
Dr. P. B. Stockdale, Dr. H. J. Klepser, and Mr. Stuart
Maher, afforded opportunities for profitable exchanges
of information and ideas.
Dr. T. F. Bates, Mr. E. C. Strahl, and other membersof the staff at Pennsylvania State University, who
studied the mineralogy of the shale for the Atomic
Energy Commission, also discussed some aspects of the
shale with us.
Members of the U.S. Geological Survey contributed
greatly to the project. R. A. Lawrence helped in many
special phases of the work; J. M. Schopf made preliminary studies of the plant remains in the shale;
Charles Milton advised on several mineralogic problems ; W. H. Monroe handled many of the administrative details. These, and J. F. Pepper, took much interest in the work and offered countless suggestions
regarding the geology. Mrs. Bernice L. McCraw compiled much of the statistical information and aided inmany ways beyond her normal secretarial duties. About
15 other people had part-time or short-time assignmentswith the project, either in the office or laboratory.
TERMINOLOGY

Some terms used in this report in describing rocks
have such different meanings to different people thatthey are defined briefly. These definitions are not intended to be any contribution to, or change in, rock terminology ; they are given merely to clarify our usage.
BOCK TERMS"Shale" denotes a fine-grained, finely laminated rockhaving pronounced fissility. As used, it is a rock term
based on structure, having only indirect reference tograin size and no implication as to mineral composition.
Fresh Chattanooga shale is massive and breaks with

6

CHATTANOOGA SHALE, BELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

conchoidal fracture, and only after weathering is it
fissile.
"Siltstone" and "claystone" differ from shale only inthat they are nonfissile fine-grained rocks classified bygrain size. Siltstone consists chiefly of grains ranging
from 0.062 to 0.004 mm in diameter that can be seen
with an ordinary hand lens of about 10-power magnification; claystone consists chiefly of particles less than
0.004 mm in diameter that cannot be seen with a hand
lens.
"Sandstone" is a rock whose greater part consists ofgrains that fall within a 0.062-2.0 mm range of diameter and that are visible to the naked eye. The term
has no implication as to mineral composition.
"Carbonaceous" is here used to denote a rock, generally dark colored, containing abundant organic material. According to some classifications, a predominance of humic organic matter is basis for terming arock carbonaceous, and a predominance of sapropelic
matter is a basis for terming it bituminous. The Chattanooga shale is known to contain both types of plantmatter, and in the past it has often been termed abituminous shale, but we are using the term "carbonaceous," which strictly has wider applicability.
Because the Chattanooga yields hydrocarbons whenheated, it has also been termed an "oil" shale, a"kerogenous" shale, or a "pyrobituminous" shale, eachadjective signifying the same quality.
COLOR TERMS

With the exception of the generalized usage of"black" and "gray," the color terms appearing in thispaper are those used in the Rock-Color Chart preparedby the National Research Council. Rock colors wererecorded carefully during detailed field studies, but
for the sake of general discussion "black" refers tocolors ranging from black to dark gray, and "gray" tocolors ranging from medium dark gray to medium
light gray. Without this modification little of the rock
could properly be called black shale.
LINEAR MEASUREMENTS

Most measurements of outcrops and drill cores werein feet and decimal fractions of a foot, though somethicknesses in this report are in inches. A few measurements of smaller magnitude were in millimeters.
SAMPLE NUMBERINGFor most outcrops, drill holes, and samples, systematic numbers were applied that would aid in recalling the location of the outcrops and would identify thestratigraphic positions from which the samples wereobtained. Inasmuch as these field numbers have beenused by some other workers in reporting their studiesof the shale (for example, Cuttitta, 1953), the system
is explained here.
Early areas of investigation were designated by arbitrarily chosen letters, such as LC or R-C, and withinthose areas the outcrops were numbered LC-15, R-C2,
etc. Later, a coordinate system was used for most
localities whereby 15-minute quadrangles were numbered from south to north and lettered from west to
east. Within each quadrangle the outcrops were numbered, thus producing such designations as 13M-7.
Table 14 gives the correlation between these field
numbers and the numbers used in this report (table 13).
For most outcrops and drill cores the individual
samples were numbered downward in a decade system
to enable ready identification of the stratigraphic units
which they represent. That system is set forth intable 1. When combined with the locality numbers
already explained, the samples have such numbers as
LC-15-12 or 13M-7-31.
TABLE 1. System for numbering stratigraphic samples[Names in parentheses are informal terminology used in the field]
Allotted

Stratigraphic unit
Maury formation (Maury) _ _Chattanooga shale:_

numbers
1-9

Gassaway member (upper black shale):Upper unit (top black shale)
11-19
Middle unit (upper gray Siltstone 1 )21-29
Lower unit (middle black shale)- _ ___ 31-39
Dowelltown member:
Upper unit (middle gray Siltstone 1 )_______ 41-49
Lower unit (lower black shale)
51-59
1 The term "siltstone" was applied at first to these gray beds thatare now called claystone.

In nearly all instances only a part of the allotted
decade was used. At most places number 11 was reserved for an upper interval of the shale where phosphate nodules were observed, though at some places it
was applied to a phosphate-nodule-bearing zone at ornear the base of the Maury formation. Locally, wherethat interval is thick, 11A, 11B, etc., were used. As
the comprehension ( of the stratigraphy became clearer
or where units were misidentified, a few inconsistencies
were introduced, but those were relatively minor. At
places where the individual units were not obvious, astraight downward succession of numbers was applied
to the samples.
SURFACE FEATURES

The chief physiographic features in the area of mostof these investigations are the Nashville Basin, theHighland Rim, the Cumberland Plateau, and the Appalachian Valley and Ridge (fig. 2).

SURFACE FEATURESKENTUCKYTENNESSEE

50

50 MILES_IFIGUEB 2. Chief physiographic features of central Tennessee and nearby areas.

The Nashville Basin, frequently referred to as theCentral Basin of Tennessee, coincides with the crestarea of the Nashville dome or arch. It has an ellipticaloutline, is about 120 miles long in a north-northeast
direction, and is about 50 miles wide. The floor of thebasin is a rolling and hilly limestone lowland about
500 to TOO feet above sea level, surrounded by a more orless flat upland 300 to 500 feet higher than the floor.
The surrounding upland, known as the Highland
Rim, is capped at the edge of the basin by rocks thatare more resistant to weathering, notably the Fort
Payne chert. Most of the high hills that rise from thefloor of the basin are capped by the more resistantHighland Rim rocks and are thus outliers of the Highland Rim. Because of their structural position on the
Nashville arch, some of these outliers are now 200 to
300 feet higher than the present rim.
Slopes between the Highland Rim and the basin are

so steep that rail and highway routes require carefulselection and extensive cuts. The Chattanooga shale iswell exposed in many of these cuts and in many beautiful waterfalls and gorge walls, some difficult of access.
An excellent drawing of one of these waterfalls, printed
in Safford (1869, facing p. 83), is reproduced here asplate 2. Concerning this fall and its associated gorge,
Safford wrote (p. 83) :The accompanying plate presents one of these falls, and willserve to show their general features, as they are all very muchalike. * * * This romantic waterfall is about two miles eastof Smithville, in DeKalb County. In addition to the main fall,a cascade, from a greater height, is seen to the right, belonging
to a much smaller and different stream. * * * The larger bodyof water falls ninety-three feet. The gorge below the falls is
exceedingly wild and picturesque. Steep slopes rising from thenarrow valley are surmounted by precipitous cliffs from one totwo hundred feet in height, towering in all, three hundred feetor more above the creek.

8

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

The position of the Chattanooga shale on the steep
slopes between the rim and the basin and on the outliers
is indicated at most places by a distinct change of slope
and vegetation. In general, the upper part of theslopes, which is underlain by the Chattanooga shale
and the Fort Payne chert, is too steep for cultivation ofcrops and so remains wooded. The lower part of theslopes, underlain largely or entirely by Ordovician
limestones, is less steep, is commonly cleared, and isplanted with corn or tobacco or used for pasture. At
most places the position of the Chattanooga shale, justabove this change in slope and vegetation, can be easily
identified by looking at the hillsides or by examining
aerial photographs stereoscopically. Most of the outlying remnants of the rim that are within the basin
have steep-sided and well-wooded crests that indicate
clearly the parts that are occupied by the Fort Payne
chert and the underlying Chattanooga shale.
The Highland Eim is a fairly smooth upland, about
1,000 feet above sea level, that surrounds the NashvilleBasin and, in general, slopes slightly away from it.
On the rim near the edge of the basin the resistant Fort
Payne chert or its equivalent is the surface formation,
but farther away successively younger formations ofMississippian age crop out. The different geographic
parts of the rim are termed the Northern, the Eastern,
the Southern, or the Western Highland Rim, depending on their directions from the basin.
The Eastern Highland Rim has an average widthof about 15 to 20 miles and is bounded abruptly on theeast by the Cumberland Plateau, which is about 1,000
feet higher. The Northern Highland Rim extends into
southern Kentucky and about 100 miles from the Nashville Basin gives way to the Lexington Basin. The
Southern Highland Rim merges southward in northern
Alabama into the valley of the Tennessee River andbeyond that is bounded by a sharp rise to the Cumberland Plateau. The Western Highland Rim, somewhat
more dissected, slopes westward, and near the western
valley of the Tennessee River passes beneath the
Coastal Plain.
The Cumberland Plateau at the latitude of Crossville,
Tenn., is about 2,000 feet above sea level but is higher
to the north and lower to the south. The eastern edge
is marked by the steep Cumberland Front that overlooks the Valley and Ridge province of east Tennessee.
The rocks beneath the plateau are nearly flat, but the
Sequatchie Valley, a striking feature in part of thearea of this study, is a long, narrow, and deep valley
trending north-northeast that has been eroded along
the axis of a sharp anticline. This valley and its southern extension into Browns Valley of Alabama is 150
miles long, is about equally divided between Tennessee

and Alabama, and exposes the Chattanooga shale andolder rocks. The ends of the anticline, which have notbeen breached, form a ridge on the Cumberland
Plateau. In Tennessee this ridge is as much as 1,000
feet above the general plateau surface, but at the southend, in Alabama, it is no more than a few hundred feetabove the plateau.
The Valley and Ridge province, where the rocks arestrongly folded, has strata ranging in age from Cambrian to Pennsylvanian. In this area the relatively incompetent Chattanooga shale has been badly deformed
and good exposures are few.
GENERAL GEOLOGYREGIONAL STRATIGRAPHY

All the exposed rocks in the area of this study are
sedimentary and range in age from Ordovician toCretaceous. Local terraces, flood plains, and othersurficial deposits of gravel, sand, and clay are ofTertiary and Quaternary age.
Most of the sedimentary rocks originated in widespread seas west of and marginal to the Appalachiangeosyncline. Limestone is most abundant, but somesandstone and shale are present. In most places theChattanooga shale lies on limestones of Ordovicianage, but locally it lies on various rocks of Silurian or
Devonian age. Wilson (1949, pi. 2) prepared a subChattanooga geologic map (pi. 3) showing the distribution of the formation on the pre-Chattanooga land
surface. Widespread gentle folding and local sharp
folding (Wilson, 1949, p. 303) was followed by erosionthat reduced the land by Late Devonian time to a fairlysmooth surface. As a result, the Chattanooga shale, as
shown by Wilson's map, lies on 23 different formations.
The Chattanooga shale, though only about 35 feetthick in central Tennessee, probably represents mostof Late Devonian time (Hass, 1953; 1956). During ourinvestigations we subdivided the Chattanooga into
three members: a basal Hardin sandstone member,which is present only in and near Wayne County, Tennessee; the Dowelltown member; and the Gassaway
member. These members are shown in table 2, page 22,
and are discussed in detail in a later part of this report.
The overlying Maury formation, in most places only
1 to 4 feet thick, is present just above the position of
the Chattanooga shale in every adequately exposed outcrop we saw within the area of this report. The Mauryis chiefly of Early Mississippian age and the only unitof Kinderhook age in the area of study, but locally thelowest part is of Late Devonian age, and the uppermost
part is probably of early Osage age (Hass, 1953; 1956).

GENERAL GEOLOGYThe Fort Payne chert of Early Mississippian(Osage)age consists chiefly of massive bedded chertand cherty limestone as much as 275 feet thick andoverlies the Maury formation throughout most of thesouthern half or two-thirds of the Nashville Basinregion, the Sequatchie Valley, and the northern partsof Georgia, Alabama, and Mississippi. The lower 50 to
75 feet of the formation at most places is mainly aresistant succession of chert beds 2 inches to 2 feetthick (pi. 44). Northward the chert grades laterally
into crinoidal reefs and calcareous and noncalcareous
claystones that have been variously called the Ridgetop
shale, the New Providence formation, and the Greasy
Creek facies of the Fort Payne chert (Bassler, 1911;
Wilson and Spain, 1936; and Stockdale, 1939). Thesenoncherty beds are the common rocks above the Maury
formation in the western valley of the Tennessee Riverand along the northern and northwestern edges of the
Nashville Basin. Green calcareous claystone and crinoidal limestone are also present locally in the lower partof the Fort Payne chert at many places along the eastern edge of the basin (for example, at Iocs. 16, 39, and126, pi. 1).
Above the Fort Payne chert is 800 to 1,000 feet ofstrata, chiefly limestone, of Mississippian age. Still
higher, a thick succession of conglomerate, sandstone,
shale, and coal of Pennsylvanian age caps the Cumberland Plateau of east-central Tennessee and northern
Alabama.
In western Tennessee and adjoining parts of Alabama and Mississippi the Paleozoic rocks are overlain
by Coastal Plain sand, gravel, and clay beds of Late
Cretaceous age.
STRUCTURE
REGIONAL STRUCTURE

The Nashville dome has been a mildly active structural feature since early Paleozoic time. Its repeateduplifts have affected the distribution of several lower
Paleozoic formations (Wilson, 1935; 1949, p. 328, 330)
and more recently have warped the erosion surfaces,
notably the remnants of the Highland Rim surface. The
pre-Chattanooga paleogeologic map (pi. 3) shows theeffects of the earlier uplifts.
Throughout most of the area the rocks dip gently
away from the crest of the Nashville dome at an
average rate of about 10 to 15 feet per mile. Superimposed on this regional dip are many minor irregularities, such as small domes, anticlines, and basins.
Local dips as high as 5° are fairly common (pi. 4(7).
Faults at a few places are known, but are uncommon.
Structure contours of central Tennessee and adjacentareas are commonly drawn on the top of the Chat-9tanooga shale (for example, Wilson, 1949, pi. 1; Kingand others, 1944), because it is an excellent horizon forsurface mapping and is almost invariably noted in drill
records.
In the southeastern part of the area of this report,
in the region of Appalachian folding, the Chattanooga
shale and Maury formation are relatively incompetentunits and are badly sheared and crumpled (pi. 4Z?).
In the deeply breached Sequatchie anticline, the Chattanooga shale and older rocks commonly dip 10° orless on its southeastern flank, but on the northwestern
flank steep dips, some of them vertical, are the rule. A
major high-angle thrust fault conceals the Chattanooga
in most places on the northwestern flank.
Walden Ridge, which is east of the Sequatchie
Valley, is the southeasternmost part of the Cumberland
Plateau. It is characterized by gentle dips except
along its steep east wall, the Cumberland Front, where
the rocks are so intensely folded that it is difficult tofind good outcrops of the Chattanooga shale. Still
farther east, in the main Valley and Ridge province ofthe folded Appalachians, all the rocks are intensely
folded, faulted, and sheared, and most outcrops of the
Chattanooga shale and Maury formation, where they
can be found at all, are too highly disturbed to permit
detailed stratigraphic study. The type locality of the
Chattanooga shale (loc. 226; Hayes, 1894b, 1894c,
1894d), in the city of Chattanooga, is in this highly
disturbed area.
CRYPTOEXPLOSIVE (CRYPTOVOLCANIC) STRUCTURALFEATURES IN TENNESSEEIn three small areas of Tennessee the Chattanooga
shale is associated with highly disarranged rocks incircular areas that are much like the Steinheim Basinof Germany for which Branca and Fraas (1905)
coined the term "cryptovolcanic" (hidden volcano), in
the belief that the feature resulted from some kind of
explosion of magmatic origin. Later Dietz (1946) proposed that the term "cryptoexplosive" be used for suchfeatures; this word, which carries a less definite implication as to origin, is used in this report.
The origin of these structural features is unknown
and is the subject of much speculation. Three theories
most often considered in attempting to explain them
are that they overlie salt-dome types of intrusions(Washburne, 1937), that they result from subterranean
explosions of magmatic gas (Bucher, 1936), and thatthey result from the impact of large meteorites (Boonand Albritton, 1938a, 1938b). As this study has contributed little or no information on the origin of thefeatures, their origin is not considered further in thispaper.

10

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

The Wells Creek cryptoexplosive feature in Stewart
County is the best known of those in Tennessee. Herethe Chattanooga shale and other rocks ranging in age
from Ordovician to Mississippian have been strongly
brecciated and faulted, and rocks in the central partof the structure are at least 1,000 feet above theirnormal position (Bucher, 1936, p. 1066-1070). The ageof this disturbance is unknown except that it took place
after middle Mississippian sediments had accumulated,and probably before Tertiary time.
The Howell feature in Lincoln County was describedby Born and Wilson (1939). The Chattanooga shale ispresent locally over this disturbed area but is muchyounger than the disturbance and shows no abnormalities attributable to it. The disturbance apparently took
place during the Ordovician period.
The third feature, at Flynn Creek, is described in thefollowing paragraphs in some detail because it obviously influenced the accumulation of the Chattanooga
shale.
FLYNN CREEK FEATURE

The Flynn Creek feature is near the northeast end of
the Nashville Basin, about 5 miles south of Gainesboro,
Jackson County (pi. 1), and is in the southern part of
the Gainesboro 15-minute topographic quadrangle,
where the maturely dissected topography has about 400
feet of relief. The disturbed rocks are exposed in the
deep narrow valleys that have been cut through theundisturbed Fort Payne chert. The feature, as mapped,
is slightly elliptical and has an average diameter ofabout 2 miles. Wilson and Born (1936), Lusk (1927),
and Conrad, Elmore, and Maher (1954; 1957) described the structure. Many of the facts here stated aresummarized from the reports by Wilson and Born, andby Conrad and others, but are supplemented by muchadditional information.
The Fort Payne chert in the area of the disturbanceconstitutes the upper 100 to 200 feet of the ridges;
below it are the Maury formation, the Chattanooga
1000'

shale, and the highly brecciated and disarranged blocksof Ordovician limestone that represents several formations. Wilson and Born (1936, p. 829) estimated thatsome of the blocks are as much as 500 feet above theirnormal position (fig. 3). The disturbance can be dated
only as post-Middle Ordovician and pre-Late Devonian.
In the valley of Bush Fork, near the southeasternedge of the feature, 150 feet of Chattanooga is present
between the Maury formation and the creek, and an
additional 49 feet has been reported in the nearby
Chaffin well in the valley bottom (Wilson and Born,
1936, p. 822). It thus appears that the shale in the
disturbed area is locally about 200 feet thick, in contrast with that in the surrounding region which is only
about 20 feet thick. Within the area of the feature
the shale dips at various angles at least as high as 20°(pi. 4Z>).
The limestone fragments below the shale range in size
from powder to giant blocks measurable in hundreds offeet and are variously oriented as if they had been
violently hurled about. Near the center of the feature
the limestone extends upward somewhat like a secondary cone within a volcanic crater. Although full structural details of the area have never been determined, it
appears that the Chattanooga shale fills a crater-likebasin surrounding a central core. The core itself isoverlain by a section of black shale thicker than thatoutside the disturbed area.
In the Flynn Creek area the abnormal thickness of
the Chattanooga shale is almost wholly in its lowest
unit. In a small creek in the northwestern part of the
disturbed area (loc. 49), a bentonite bed in the upper
unit of the Dowelltown member of the Chattanooga ispresent at its normal position about 17 feet below thebase of the Fort Payne chert, virtually the same position as at nearby localities just outside the disturbed
area. Below the bentonite, black shale is exposed down
the creek bed to the base of the formation, which is 125
feet lower and some 500 feet closer to the center of thestructure. If allowance is made for the dip of the shaleW

fLarge block of Lowvillelimestonef

SHATTEREDf

AND

BRECCIATED

f

LIMESTONEf

SEA LEVEL
1 MILEAPPROXIMATE VERTICAL EXAGGERATION

X 3

FIGURE 3. Cross section of the Flynn Creek cryptoexploslve feature, Jackson County, Tenn. Note the abnormal thickness of the Chattanooga
shale, the relation of the shale to the underlying brecciated formations, and the sagging of the Fort Payne chert in the disturbed area.
(From Wilson and Born, 1936, p. 824, fig. 3. Used by permission.)

GENERAL GEOLOGY

along the creek, the beds below the bentonite would
have a true thickness of only 35 to 40 feet. It is more
likely, however, that the lower beds of the Chattanooga
have an initial dip and thicken to the south in a wedgeshaped manner, between horizontal top and a dipping
floor, and that the actual thickness of the shale where
the base was observed is about 140 feet. Apparently
nearly all the extra thickness here, and probably elsewhere within the structure, is in the lower part of the
Dowelltown member, the first part of the formation to
be deposited. (See pi. 7 and fig. 5 for representations of
the lithologic units of the formation in this part ofTennessee.) The same conclusion has been reached byother investigators (Conrad and others, 1957) who
measured as much as 166.4 feet of beds of the Dowelltown member in the feature and observed that most of
this overthickening is in the lower unit of the Dowelltown member.
The abnormally thick Chattanooga shale has
previously been assumed to have accumulated in a
crater that was present at the beginning of Chattanooga time, but to us that explanation is untenable.
More likely, the disturbed area and the surrounding
region had been reduced by erosion to a uniform level
and the fragmental material in the structure subsided gradually during the accumulation of the black
muds. Several types of evidence support these con:elusions.
First, by whatever theory one explains the cryptoexplosive disturbance, it must be assumed that a large
mass of rock was pushed or hurled upward; yet notrace of ejected fragments has been found at or below
the base of the Chattanooga shale in the many wellexposed outcrops within 5 miles of the rim. It is inferred, therefore, that enough time for the removal ofthis debris elapsed between the shattering of the rocks
and the deposition of the Chattanooga.
A second indication that no crater existed just prior
to Chattanooga time is the absence of lake deposits andof rock debris from the walls of the supposed crater.
A crater 200 feet deep on the Devonian peneplain
would doubtless have contained a lake in which plantremains and mud would have accumulated and into
which rock debris would have been washed from thewalls. However, no lake deposits appear to be present
between the explosion breccia within the disturbed area
and the overlying Chattanooga shale. Wilson and
Born (1936, p. 821-822) described a "bedded breccia"
that is present locally just below the black shale, andlater Conrad and others (1957, p. 16) described thesame material as a "fresh-water" limestone. Examination of this limestone in the creek bed of Cub Hollow
near Antioch School by Hass (oral communication,

111949) revealed lower Upper Devonian conodonts. The
example of talus breccia cited by Wilson and Born (p.
821) is probably land-slip material of Kecent age. It
appears to us, therefore, that the first sediment deposited within the "crater" was a marine deposit ofearly Late Devonian (Chattanooga) age.
The observed dips of the shale are a third indicationthat the basin was formed during Chattanooga deposition. Within the area of abnormal thickness, thelower beds of Chattanooga shale customarily dip asmuch as 20° toward areas where it is thickest. It ishighly unlikely that the fine muds could have accumulated on the steep slopes to thicknesses of manytens of feet without slumping toward the deeper areas.
Because the beds show no sign of slumping, it is believed that the layers of mud accumulated in a nearlyhorizontal position and acquired a dip toward the center of the structural feature only after burial and subsequent depression.
A fourth type of evidence against a pre-existing"crater" is the almost identical appearance and composition of the abnormally thick shale and the normal
shale of the surrounding region. Had the muds accumulated in a deep crater, even one that came into
existence at the beginning of Chattanooga time, theywould almost certainly have differed from the normal
shale in grain size, organic content, and bedding characteristics. Instead, the similarity in both compositionand stratification strongly suggests that the muds accumulated under virtually the same conditions as thosein which the Chattanooga muds accumulated elsewhere.
The following proposed explanation of the thick accumulation of mud in the Flynn Creek area seems consistent with the observed facts: Whatever the origin of
the explosion or disturbance, sufficient time followed
for any ejected debris to be removed and for the area
to be leveled by weathering and erosion. By the time
the Chattanooga sea reached the region, the surface wasnearly as smooth as that elsewhere on the peneplain.
Upon flooding by the Chattanooga sea, some of the finer
fragmental limestone material was reworked into thestrictly local deposits of sedimentary breccia that contain the Upper Devonian conodonts. The "bedded
breccia" of Wilson and Born, or "fresh-water" limestone of Conrad and others is thus merely a local f aciesof the basal sandstone bed of the Chattanooga shale,
a bed that elsewhere varies greatly in composition
according to underlying rock types (pp. 23, 25). Acidsea water, whose presence is indicated by the black shale,is assumed to have had a greater dissolving power on
the limestone than did the ground water that had previously saturated the breccia. As the supply of acidic
water became plentiful it may have caused solution and12CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

compaction of the loose limestone breccia and powder
to considerable depths within the structure. The
steadily increasing weight of the overlying muds may
have contributed to the settling process. Once thesubsidence started, a slight depression was formed on
the sea floor and mud could migrate into it from thesurrounding area.
By this explanation, the lower beds of the Chattanooga shale would not acquire dips of appreciablemagnitude until they were buried beneath many tensof feet of overlying mud and were sufficiently confined
or indurated that they did not flow.
The settling process, which involved more than 150
feet of lowering of the original surface, was largely
completed by the time the lower unit of the Dowelltown
member had been deposited, as indicated by normal
thicknesses of the overlying units of the shale and theMaury formation. Over the thickest part of the Chattanooga shale in the Flynn Creek crater, however, theMaury formation and the overlying Fort Payne chert
are as much as 100 feet lower than in the surroundingarea (fig. 3). This lower position of the higher beds
over the disturbed area is presumably a measure of thedifferential compaction of the abnormally thick shale
as compared with the normal shale in the nearby surrounding area, in consequence of the load of about 1,000
feet of rocks of Mississippian age and an unknown
thickness of rocks, probably at least 1,000 feet, ofPennsylvanian age. It is especially noteworthy thatany compaction of the muds in excess of about onethird of original thickness had to take place before theend of Chattanooga time, for the contents of the 300foot-deep crater are now only 200 feet thick. Even
more notable is the fact that most of this early compaction took place during Dowelltown time; had it continued through Gassaway time, the Gassaway member
would presumably have an abnormal thickness.
A similar excessive thickness of a formation overlying a cryptoexplosive area is at the Howell feature in
Tennessee where the Fernvale formation has abnormal
thickness and dips. Born and Wilson (1939, p. 382)
postulated a simultaneous subsidence of the crater floor
and deposition of the sediments, events parellel to what
we believe happened at Flynn Creek.
A possible corollary to the theory of simultaneous
subsidence and deposition carries definite implications
regarding sedimentation that occurred in the Chattanooga sea. It has just been shown that the subsiding
crater area must have been filled with black mud fromthe surrounding area, yet measurements of the blackshale over a large part of Tennessee show that it has
no tendency to be significantly thinner near the Flynn
Creek area than elsewhere in that part of the State. It

seems, therefore, that mud on the sea floor was sufficiently agitated, even though weakly, that it moved
about and tended to fill any low places. This shifting of
the mud particles, though slight at any one time, wasprobably enough to keep the Chattanooga sea floor wellgraded at all times. The mud particles may well have
moved many miles along the sea bottom before theyreached their present places.
CHATTANOOGA SHALE

The Chattanooga shale is part of a blanket of blackshales of early Late Devonian (or possibly late Middle
Devonian) to Early Mississippian age that are present
throughout much of the interior of North America.
The general distribution and nomenclature of theseblack shales and their correlative rocks in the UnitedStates are shown on plate 14. Black shales of similar
age continue northward from Montana under theGreat Plains province of Canada.
HISTORY OF THE NAME

The black shale of Tennessee was recognized as apersistent and distinctive unit at least as early as 1835,
when it was described by Troost (1835, p. 6-8) as"aluminous slate or shale" [italics by Troost]. In 1837
he noted (p. 15) that a siliceous stratum [Fort Payne
chert] is always separated from the underlying limestone sequence " * * * by a bed of argillaceous schiste(ampelite alumineux) of a black color, containing
pyrites and occasionally small seams of bituminous
matter, resembling sometimes coal." His reports of1840 (p. 16-17), 1841 (p. 33), and 1843 (p. 18-22, 29)refer to it as aluminous slate or simply as shale or slate.
In 1851 Safford (p. 352, 358-359) referred to the"black or bituminous slate," or simply the "black slate"
as one of the five major stratigraphic divisions of
middle Tennessee. In 1856 (p. 158) he again referred
to it as the "black shale," but in 1869 (p. 151, 154, 162163, 329-337) he consistently called it black shale.
In 1891 Hayes (p. 142, 143) applied the geographic
name "Chattanooga black shale" but did not specify atype locality. In 1894 he stated in three U.S. Geological
Survey folios (Nos. 4, 6, 8) : "Typical exposures of thisshale appear in the north end of Cameron Hill, within
the city limits of Chattanooga, from which locality it
takes its name." Cameron Hill is thus the type locality,
though the outcrop is on a thickly wooded slope, isbadly weathered, and is too deformed by folding andfaulting to permit detailed study (for photograph ofthe outcrop see Hass, 1956, pi. 5). Gradually the word
"black" has been dropped, in accordance with generally
accepted practice, and the unit is now known as theChattanooga shale. That name has been widely adopted

13

CHATTANOOGA SHALE

for strata in Tennessee, Georgia, Alabama, Mississippi,
Kansas, and parts of Arkansas, Oklahoma, Kentucky,
Illinois, and Missouri.
In 18YO Andrews (p. 62) applied the name "Ohioblack shale" to outcropping beds in Ohio that are of
Late Devonian age and are virtually correlative with
the Gassaway member of the Chattanooga shale inTennessee. That term is generally used for beds innorthern Kentucky on the east side of the Lexington
Basin, where the black shale of Devonian age can be
distinguished from the overlying Sunbury shale ofMississippian age by the presence of the intervening
and distinctive Petersville shale of Morse and Foerste(1909), which is a thin representative of the Bedford
shale and Berea sandstone of Ohio.
In 18Y4 Borden (p. 150, 152, 158, 1Y2) applied thename New Albany shale to black shale in southern
Indiana that is a partial correlative with both the Ohio
shale of Devonian age and the overlying Sunbury shaleof Early Mississippian age. That name is now commonly used also for beds in northern and central Kentucky west of the region where the presence of the Bedford shale and Berea sandstone permits the Ohio andSunbury shales to be distinguished; it is also used forbeds in southeastern Illinois. The same beds in the subsurface of western Kentucky, however, are commonly
called the Chattanooga shale.
The names Ohio shale and New Albany shale have
21 and 1Y years priority, respectively, over the name
Chattanooga shale, and one of them should, perhaps,
by a strict application of the principle of priority, replace the term Chattanooga shale, although the threenames were applied to rocks having somewhat different,
though overlapping, age ranges. For nearly 50 years
suggestions to that effect have been made (for example,
Ulrich, in Ulrich and Smith, 1905, p. 25), but none
received wide acceptance.
Freeman (1951, p. 43) proposed that the names Ohio,
Chattanooga, Sweetland Creek, and Antrim all beabandoned in favor of New Albany shale because, inspite of some differences in age, the beds so designatedrepresent a continuous depositional unit ranging from
Late Devonian to Mississippian. She stated:
If one name is to be used it should be the one first applied.
The term Ohio shale was used a little before that of New
Albany but it is not so inclusive.
* * * because this black shale is such a convenient marker
and more widely used than any other in the Paleozoic, a single
name for the unit seems desirable. It is suggested here that,since New Albany has priority as an inclusive term, it should
be in use generally.

Although there is logic in this argument, widespread
usage of long standing has so firmly entrenched thename Chattanooga shale in the literature and in therecords of geological surveys and of industrial companies that to abandon it now would cause more confusion than seems warranted. For that reason we
continue to use the term "Chattanooga shale."In the 19th century both Safford (1869, p. 330) andHayes (1891 and several later reports) included in the
Chattanooga shale the overlying thin unit of greenish,
more or less glauconitic and phosphatic shale, siltstone,or sandstone. Later Safford and Killebrew (1900, p.
104, 141-143) treated it as a separate unit. Since then
the tendency has been to recognize it as the Maury
member of the Chattanooga shale, as the basal bed of
the immediately overlying formation, or as a separate
formation. In this report it is treated as the Maury
formation.
PBE-CHATTANOOGA SUBFACE
GENERAL, CHARACTER

Throughout the area of this study the Chattanooga
shale rests on a peneplain that is notable for its extent
and degree of perfection. In the Tennessee area alone
the shale rests on no less than 23 different sedimentary
formations (pi. 3), as mapped by Wilson (1949, pi. 2),
ranging in age from Middle Ordovician to Middle
Devonian. The older beds were tilted so slightly before
Chattanooga time that in most outcrops the shale appears to parallel the older rocks; at a few places anangular discordance is visible (pi. 5A) but is rarely
as much as 1°. Limestones, sandstones, and shales werebeveled and planed during what must have been a timeof unusual crustal stability until a wide area was reduced to an almost featureless plain barely above sea
level. Similar stability, except for a probable slight
general subsidence, continued throughout Late Devonian and Early Mississippian time as the sea progressively spread and inundated more and more land; even
the Nashville dome, notable for its several earlier andlater uplifts, shows evidence of only slight arching
during that time.
Further evidence of the smoothness of the pre-Chattanooga peneplain is the uniformity in thickness of the
Chattanooga shale. The several lithologic units of the
shale are notable for their nearly constant thicknesses
in large areas along the eastern edge of the NashvilleBasin, and probably beneath much of the Eastern
Highland Klm. Evidence in the Flynn Creek area
indicates that the muds were carried to low points andthat current action kept the sea floor well graded.
Along most of the eastern edge of the Nashville Basineven the lower unit of the Dowelltown member commonly has a thickness of about 4 to Y feet, and at only
a few places is it much thinner or thicker.

14CHATTANOOGA SHALE, BELATED BOOKS, CENTEAL TENNESSEE AND NEARBY AREAS

In general the rate of thickening or thinning of the
Chattanooga shale is remarkably low. Over the entire
area, with the exception of Flynn Creek and a few
other small areas where special conditions prevailed,the average rate of thickening or thinning is about 3 to
5 inches per mile. Several lines of sections, from 20 to
60 miles long, could be drawn to illustrate this gradualchange of thickness. The line of section in figure 4
shows an average northward increase of thickness,away from an island area, of about 3 inches per milefor 15 miles. A similar gradual and regular thickening
eastward from the same island area can be seen at
locality 138 near Bodenham in western Giles County
where a succession of outcrops shows a regularly increasing thickness of the shale. Here, in a creek bed,
100 yards east of the Giles-Lawrence County line, about
0.35 foot of phosphatic siltstone of the Maury formation rests directly on basal sandstone, and no blackshale is present; 50 yards downstream, at the sit© of a
big spring, about 0.06 foot of black shale is present
between the Maury and the basal sandstone of the
Chattanooga; and another 75 yards downstream theblack shale wedge is about 0.9 foot thick. Outcrops
farther east show progressively greater thicknesses ofthe shale. These two examples of gradual onlap of the
Chattanooga shale are believed to typify conditions
that existed regionally as the sea spread slowly over the
peneplain.
SUB-CHATTANOOGA RESIDUUM

Instead of the normal sharp contact between the
Chattanooga shale and the underlying fresh limestone,a residual silty clay is present below the shale at manyoutcrops throughout the area of this study (pi. 5Z?).
The clay ordinarily ranges in thickness from a few
inches to at least 15 feet and is various shades oforange and brown. For the most part it is unstratified
and structureless except that it commonly has a coarse
and variable color banding, the most conspicuous bands
being nearly black because of the presence of manganese oxide. Locally the clay contains uncompressedmolds of fossils like those of the underlying limestone.
It has a sharp upper contact with the Chattanooga
shale, and commonly rests abruptly on weathered
limestone that has an irregular or even pinnacled uppersurface. The weathered limestone grades downward
through an interval of several feet into fresh limestone.
The residuum has been found by careful search atabout a quarter or a third of all the examined outcropsof the Chattanooga, though at many it is found only
when the concealed basal contact of the shale is dug out.
The residuum is most often found in highway cuts
where only 10 or 20 feet of the shale is present, but

exceptionally it is overlain by the entire thickness ofthe shale. At some places the shale above the residuum
is considerably cracked and slumped, but at others it
shows few fractures or signs of slumping.
This silty clay, obviously formed by weathering of
the underlying limestone seems to permit only two
explanations of origin: Either it is an ancient limestone
residuum that was buried by the black muds of the
Chattanooga sea, or it is the insoluble residue fromlimestone that has been dissolved by ground water orsurface water, or both, since the time of Chattanooga
deposition. It is probable that most, and perhaps all, of
the residuum was formed since the land surface waseroded to about its present position.
The residuum has been observed below the blackshale by several previous writers, some of whomthought of it as a pre-Chattanooga residuum, though
they presented few arguments to support their opinion.
Foerst© (1901, p. 430-431) mentioned residual soil atthe base of the Chattanooga shale in the Tennessee
phosphate area. Ulrich (1911, p. 454-459, 464-465)
discussed the presence of residual soil along unconformities and mentioned such material as being either
just below or in the base of the Chattanooga but cited
no convincing evidence at localities within the area of
our investigations. Kindle (1912, p. 122-123) describedand illustrated residual clay below the black shale andconsidered it to be definitely a residuum on the preChattanooga land surf ace. Later Jillson (1951a, p. 48;
1951b, p. 5-6) mentioned the presence of an "old soil"
below the Chattanooga shale in Cumberland County(loc. 14A), but he did not describe it or present evidence of its origin.
Several facts suggest a pre-Chattanooga age for the
residuum: (a) Superficially it looks somewhat like theresiduum in present-day limestone areas, except that
nothing resembling the A and B soil horizons of pedologists has been identified; (b) in some places the rocks
above and below it show no excessive recent weathering; (c) the residuum has been observed only at thecontact between the impervious Chattanooga shale andthe almost impervious underlying limestones; (d) atmost exposures of the residuum the clay can be traced
laterally as far as the base of the shale is exposed.
On the other hand, a post-Chattanooga age of theresiduum is indicated by the following facts: (a) The
residuum has not been found in the freshest deep highway cuts, but only at outcrops where there has been apossibility of recent weathering or where roots havebeen able to penetrate; (b) the residuum is not present
in any of the Y5 drill cores that have penetrated thelower contact of the shale; (c) petrographic study byCharles Milton of the U.S. Geological Survey has

15

CHATTANOOGA SHALEPERRY,J-'~~s ^

.

WAYNE

0

5

0

5 FEET

0
Hohenwald
LEWIS

vJ

v. _^i| LAWRENCE 'FIGURE 4. Map and cross section of the Swan Creek area of Tennessee showing the gradual thickening of the blackshale unit of the Chattanooga shale seaward from a large island. In 15 miles the average rate of thickening is about
1 foot in 4 miles. The basal phospbatic sandstone ("blue phosphate") is omitted in this compilatiou.

16

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

shown the presence of abundant rhombohedral voids,
indicative of the removal of calcite or dolomite crystals
by solution cavities that could hardly have existed
throughout a long period of soil formation and subsequent compression beneath 1,000 to 2,000 feet of overlying rocks; (d) the empty molds of calcareous-shelled
fossils could also have hardly escaped being compressedand destroyed.
Milton concluded (Milton and others, 1955) that surface water seeping through cracks or over the outcropping surface of the shale became sufficiently charged
with sulfuric acid derived from the disintegration of
pyrite to attack the underlying limestone. This process
removed most of the calcium carbonate but left a clayrich residuum. Among the products of this process isthe rare mineral basaluminite (2A1203 3SO3 10H2O)
that was first described only a short time before its
discovery in Tennessee (Hollingsworth and Bannister,1950).
In some places the solution of the limestone has
allowed the overlying shale to settle and crack, but inother places surprisingly small amounts of subsidence
have taken place. Possibly subsidence has been delayedby the presence of enough undissolved pinnacles andridges to permit the shale to span the areas of deeper
solution without appreciable failure.
The thickest known exposure of this sub-Chattanooga residuum is 8 miles southwest of Gainesboro,
Jackson County, Tenn. (loc. 51). There a 15-foot handauger hole penetrated a nearly homogeneous and unstratified silty clay without reaching the limestone, andscattered poor exposures down the hill show similarmaterial for another few feet. Just west of Gainesboro(loc. 40) a recently widened highway cut shows a continuous layer of the residuum extending for 100 to 200
feet, ranging in thickness from about 4 inches to 2Vi
feet and lying on an irregularly pinnacled surface ofleached limestone. One of the best places to see a complete cross section of the residuum resting on an irregular limestone surface is about 7 miles northwest of Manchester (loc. 108). There the residuum ranges in thickness from a few inches to about 2Vi feet, and has
marked color bandings, apparently the result of different degrees of concentrations of manganese and ironoxide at different vertical positions.
On the western side of the Nashville Basin similarmaterial is present beneath the Chattanooga shale atover half the observed outcrops. Near Pulaski, blackshale overlies residuum that occupies small troughlike
depressions as much as 5 feet deep between pinnaclesof the limestone (pi. 6B).

AGE OF THE CHATTANOOGA SHALEHISTORICAL SUMMARY

For 75 years geologists have held conflicting opinions
on the age and correlation of the Chattanooga shale. It
has been generally agreed that its age is Late Devonianor Mississippian, but there the agreement ends. Some
investigators have thought the black shale is of Late
Devonian age, others have been convinced of its Mississippian age, still others have thought it is of bothages, and a fourth group has considered it a timetransgressing near-shore facies of different ages in different places.
Ellison (1946, p. 102) summarized the status of thecontroversy as follows:* * * there exist three present-day interpretations of the ageof the Chattanooga and its equivalents. The paleobontanists,
some conodont workers, and the United States Geological Survey geologists have much evidence that these formations arein the greater part Devonian in age. A number of workers,
including some petroleum geologists and a few State Geological
Survey men, prefer to remain neutral and classify the Chattanooga problem as Mississippian-Devonian. Many petroleum
geologists, some conodont workers, and a number of State
Geological Survey men believe that these beds are definitely
Mississippian in age.

Many papers have been written on the age of the
Chattanooga shale and its correlatives, but much of the
published information is incorrect and inaccurate. The
chief reason for the lack of acceptable data is thegeneral absence, except at a few widely scatteredlocalities, of the fossils commonly used in determining
the age and correlatives of a formation; instead, theshales contain inarticulate brachiopods, a few arthropods, spores and other plant remains, fish remains,conodonts, and other fossils that are not commonly
used. Of these fossils, conodonts are now considered
to be the best indicators of the age and correlatives ofthe stratigraphic units that constitute the black shale
sequence. Significant conodont genera are common in
the black shales, and the age interpretations of thisreport are based on a detailed study of the conodonts
byHass (1956).
Many attempts to determine the age of the Chattanooga shale have been based on apparent gradations
or close associations with rocks of known age and on
unconformities that investigators have supposedly
identified in the sequence. Abrupt and widespreadlithologic changes have been interpreted as unconformities, different thicknesses of the Chattanooga
have been assumed to indicate erosion at the end of
Chattanooga time, and a layer of large phosphate
nodules at the base of the Maury formation has evenbeen mistaken for a basal conglomerate.

CHATTANOOGA SHALE

Both Safford (1869) and Hayes (1891 and later)
considered the Chattanooga shale to be of Devonian
age, and it was generally so accepted for many years.
In 1898 Girty summarized the then-known scanty
f aunal evidence on the age of the black shales in theeast-central States. Few fossils had been found that
could be correlated with the standard Devonian sectionin New York, yet nearly all the evidence pointed to a
Middle or Late Devonian age (Marcellus or Genesee).
In 1905 Ulrich embarked on a notable series of controversial statements concerning the black shale when
he proposed (in Ulrich and Smith, p. 25) that the term
Chattanooga be abandoned in favor of the older term
Ohio shale. Grabau (1906, p. 599) rejected this proposal, and Ulrich later reverted to using the term Chattanooga.
In 1906 Grabau (p. 593-613) challenged Girty's conclusion that the black shale is of Devonian age by expressing the view that it is a basal f acies of a sedimentary sequence formed in a transgressing sea, andthat its age ranges from Late Devonian to Early Mississippian. In following years this theory was widelyseized upon by proponents and opponents, and the"black shale controversy" was well underway.
In 1909 Morse and Foerste published the significant
discovery that the Sunbury and Ohio shales, which areseparated in Ohio by the Bedford shale and Berea sandstone, merge southward in Kentucky by the thinningand disappearance of the Bedford and Berea. At
Irvine, Estill County, Ky., 3 feet of Sunbury shale(Mississippian) is separated from 94 feet of Ohio shale(Late Devonian) by only 1^ feet of the Petersvilleshale of Morse and Foerste. Morse and Foerste also
showed that the Sunbury shale thins southward more
gradually than does the Petersville, so it probably
continues beyond Irvine and rests directly on the Ohio
shale. The fact that the topmost black shale in eastern
Kentucky is of Mississippian age and that the rest isof Late Devonian age has been variously cited bydisputants during the succeeding years of the controversy, yet stratigraphic and fossil evidence tied tothis relationship has at times been misinterpreted,distorted, or ignored.
In 1912 Ulrich prompted further controversy by proposing that some of the black shale units of the eastern
United States be removed from the Devonian system.
Like Grabau, he was of the opinion that the blackshales are of different ages in different places, but hewas impressed by the magnitude of the unconformity
at the base of the shale and believed that systemic
boundaries should be based on world-wide diastrophisms. Accordingly, he proposed that the range ofthe Waverlyan system (the now-abandoned term for17

the lowest part of the Carboniferous systems) be extended downward to include all the Chattanooga shaleand several other black shale correlatives, thereby
assigning them to what is now known as the Mississippian system. He further proposed that a new series,
the Chattanoogan, be established at the base of the
Waverlyan system to include the Huron, Olmsted,
Cleveland, and Bedford shales, the Berea sandstone,
and the Sunbury shale, all of Ohio, and the Chattanooga shale of Tennessee and Kentucky. Ulrich's
suggestions on the age and classification of the blackshales were not accepted.
Kindle was one of the few writers who immediately
rejected the opinions of Grabau, Ulrich, Bassler, andothers who advocated a Waverlyan (Mississippian)age of the Chattanooga shale and much or all of the
Ohio shale. Concerning one of the statements that had
been made on the age of the black shales he wrote (1912,
p. 128) :[It] is comparable to some which have followed it in thepoverty of evidence on which it rests and the positive phrasing
which might mislead one unfamiliar with the subject to supposethat it represents an established, fact.

Kindle also called attention to the abundant conodonts that are present throughout the Chattanooga'
shale and in the related black shales "from Lake Erieto Alabama" and correctly predicted (1912, p. 128) the
valuable evidence they would someday supply:
When they [conodonts] have been described and the species
which are confined to the upper and lower horizons of the shaledistinguished, they will prove an invaluable aid in correlating
the different parts of the Ohio shale in Ohio with their equivalents in the Chattanooga shale in Kentucky and farther south.
Until this has been done, however, any attempt to make use of
these fossils in correlating subdivisions of the Ohio and Chattanooga shale must be considered premature and futile.

The views of Kindle on the age and correlation of the
Chattanooga shale do not differ materially from thoselater presented by Hass (1956), views that were based,
as Kindle predicted, on a careful study of the conodonts from the large area between New York, Tennessee, Oklahoma, and Michigan.
Mather (1920) believed that in Sumner County,
Tenn., and Alien County, Ky., there are really two
black shale formations separated, at least locally (ourloc. 206 in Sumner County), by an angular unconformity. He considered that the upper was of Mississippian age but thought the lower might be of Devonian age. He recognized the thin sandstone bed at thebase of the upper unit that Campbell (1946) later
named the Bransf ord sandstone member of his Gassaway formation. Mather proposed no revision of theblack shale terminology.

18

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

Swartz (1924) early in his investigations consideredmost of the Chattanooga shale at Chattanooga andsome nearby areas to be of Cleveland age, but he believed the uppermost part to be of Mississippian age.
Later work (1926, 1927) in northeast Tennessee andsouthwest Virginia led him to assign similar ages to amuch thicker and presumably equivalent shale sequencein that area. Still later (1929) he concluded, on thebasis of fossils found in the middle unit of the succession, that most, and perhaps all, of the shale sequence
in northeast Tennessee and southwest Virginia is ofMississippian age, and that all the formation in the
Chattanooga area is of Mississippian age.
In 1930 Morse (p. 55-61) reasoned, largely on thebasis of a supposed overlying unconformity, that an
impure sandy and gray shaly facies of the Chattanooga shale in northeast Mississippi, which he termed
the Whetstone Branch formation, is of Devonian rather
than Mississippian age. He was one of the few investigators after 1925 who insisted on a Devonian age
for the Chattanooga shale.
In 1930 Savage (p. 14-21) presented evidence that
the New Albany shale of Kentucky is of late Devonianage (Tully and Genesee).
Pohl (1930) stated that the Chattanooga shale consists of two distinct formations separated by a widespread and significant unconformity and that bothare of Mississippian age. Another black shale unit,
present locally below these in the northern part ofTennessee, he designated as the Trousdale shale, which,he stated, contains fossils permitting a correlation with
Genesee-Portage black shales of the Devonian sequencein New York; for this new unit he cited no paleontologic information and mentioned no specific localities.
In 1931 Savage and Sutton summarized briefly
previous views regarding the age of the black shales in
Ohio, Kentucky, and Tennessee. They presented evidence that the lower part of the Chattanooga shale in
Alien County, Ky., is of Late Devonian age, but that
locally some beds of Mississippian age are present at
the top. They differed from Pohl as to the relative
amounts of Devonian and Mississippian strata present,
as shown by their closing statements (p. 448):
we disagree with him [Pohl] in his conclusion that the Upper
Devonian is represented in tills part of Kentucky and northcentral Tennessee by only local occurrences of black shale. Ourstudies would indicate that the Mississippian phase of the blackshale, rather than the Devonian, is the one which is local in its
occurrence.

In 1932 Bassler (p. 137) stated that not one of the 50
species of conodonts studied by him and Ulrich fromthe black shale in Alabama and Tennessee is identicalto a species from an equally large assortment from

Devonian shale in New York, but that many are identical with those found in the Mississippian in northern
Ohio. These opinions influenced many geologists andsome State geological surveys to reclassify the Chattanooga shale as of Mississippian age. It should bepointed out, however, that Bassler's Mississippian shaleunits in Ohio are parts of the Ohio shale which is generally considered to be of Devonian age but which
Ulrich (1912) assigned to his "Waverlyan system. The
supposed Hardin sandstone collection from the Mount
Pleasant area in Maury County, Tenn., where a large
number of the southern species were collected (seeUlrich and Bassler, 1926), is overlain directly by theMaury formation. In that area no black shale ispresent. The abundant conodonts in the sandstone inquestion are identified by Hass (1956) as Upper Devonian species, and he considers that the sandstone isequivalent to a part of the Gassaway member of the
Chattanooga shale. However, as it is a very thin sandstone unit immediately underlying and lithologicallytied to the Maury, it is here referred to as the basal
sandstone of that formation.
Huddle (1933) concluded from a study of the conodants that most of the New Albany shale in southern
Indiana and northwestern Kentucky is of Late Devonian age and that only the uppermost 5 to 10 feet isof Mississippian age. Although he did not extend
his studies south to the area of the black shales that arecommonly known as Chattanooga shale, his conclusions
are significant because they differ from the earlier onesof Ulrich and Bassler based on conodonts. Huddle's
studies may be considered the forerunner of the ones
that are restoring most of the Chattanooga and theequivalent New Albany shale to the Late Devonian.
Klepser (1937), in a thesis published only in abstract
but quoted freely by Stockdale (1939), accepted ingeneral the Grabau theory of progressive overlap to thesouth and of the Mississippian age of the Chattanooga
shale. His reasoning was based on (a) the apparent
conformable relations that exist between the Chattanooga shale, Maury formation, and overlying formations, and (b) his conclusions that the formations next
above the Maury are progressivly younger to the south.
He stated, as quoted by Stockdale (1939, p. 55):
Since the Maury is conformably overlain by formations ofvarious ages, ranging from Fern Glen to upper Keokuk, it follows therefore, that the Maury, and the Chattanooga which
everywhere grades up into the Maury, must be time transgressing units, representing the basal shore phase of a sea advancing
southward. * * *The advocates of a Mississippian age for the Chattanooga
shale have, with a few exceptions, stated that the shale is ofKinderhookian age. As the evidence to be introduced * * *will attempt to show, however, the Chattanooga shale of east-

GEOLOGICAL SURVEY

A. BASAL PART OF THE FORT PAYNE CHERT
Characteristic layers of almost solid chert from 2 to 12
inches thick. Watch near center gives scale. Locality
78. Photograph by Andrew Brown, 1948.

PROFESSIONAL PAPER 357

PLATE 4

B. FOLDED AND CRUMPLED BEDS OF THE UPPER(GASSAWAY) MEMBER OF THE CHATTANOOGASHALE ON EAST SIDE OF THE SEQUATCHIE
VALLEY
Below the hammer, nearly a foot of shale of the lower(Dowelltown) member rests on the basal sandstone, here
about 8 inches thick. Locality 220. Photograph by
R. C. Robeck, 1948.

C. GENTLE SYNCLINE IN THE EASTERN HIGHLAND RIM AREA
The gap near center cuts through the Chattanooga shale, the one at left cuts into it.
The steep slope at right rises about 400 feet above Caney Fork, which is just below
field level. Center Hill Reservoir now covers the field in the foreground. Locality
is just downstream from Sligo bridge, De Kalb County, Tenn. 1948.

D. DIPPING BEDS OF THE CHATTANOOGA SHALE ON SLOPING SIDES OF THE
FLYNN CREEK CRYPTOEXPLOSIVE FEATURE
The shale dips about 20°. At several places on this slope, including the foregroundoutcrop, the underlying brecciated limestone is well exposed. South side of Flynn
Creek, about half a mile west of Antioch school and church, Jackson County, Tenn.
1952.

GEOLOGICAL SUBVFYPROFESSIONAL PAPER S57

A. ANGULAR UNCONFORMITY OF ABOUT 4° AT BASE OF CHATTANOOGASHALE, WEST OF NASHVILLE, TENN.
The 6-foot rule stands on limestone of Silurian age (as mapped by Wilson, 1949) atbase of Chattanooga shale, marked by the white line; top of rule is just below theMaury formation, which is here about 0.6 foot thick. Higher beds are New
Providence (Ridgetop) shale. Locality 196.

-

f
j

m

' JyAr
-

' ^ -

'

"^

v ^r« ^ . *i v'

^ . n.JtoT^l * "- .-t- / Jf^T

B. SUB-CHATTANOOGA RESIDUUM NEAR PULASKI, GILES COUNTY, TENN.
The shovel leans against residuum between limestone pinnacles. The hammer rests on
a residual layer of chert that can be traced into the pinnacles. Upper part ofphotograph shows Chattanooga shale somewhat slumped. Locality 137. 1951.

% ^ * ** -? «*r^

>4 '- A. ~*':isr*<. 'l^^'A_v» . "!

»PLATE 5»i»"*f? x

.

'* -

*.^-

-^ "-'^-

-,<

*

-It

«'W

K^HH*("» --T "*'--*'***-

-

«

T^ *

*"^W i* . **~"7.^;^ ;^^fe--^r-^^l^,£?

C. PHOTOMICROGi \PH OF A TASMANITES SPORE IN GRAY CLAYSTONE OF THE UPPER UNIT OF THE DOWELLTOWN MEMBER OF THE
CHATTANOOGA SHALE
The matrix consists chiefly of fine particles of quartz, mica, and clay.

Some of the black grains are pyrite.

From a diamond-drill core, locality 93.

X 300.

GEOLOGICAL, SURVEY

PEOFESSIGNAL PAPER 357

PLATE 6

A. MASSIVE BLACK SHALE OF THE GASSAWAY MEMBER OF THE CHATTANOOGA SHALE OVERHANGING THE SHALE OF THE DOWELLTOWN MEMBER
The shale of both members looks much alike when fresh, but, as shown in the photograph, the lower member yields more readily to weathering.

Locality 204.

1952.

B. CHARACTERISTIC OUTCROP OF THE CHATTANOOGA SHALE IN DEKALB COUNTY, TENN.
Below the overhanging ledge of the Gassaway member are the less resistant beds of the upper unit of the Dowelltown member, which consist of alternating gray claystone
and black shale. Locality 70. 1953.

GEOLOGICAL, SUEVEY

PROFESSIONAL, PAPER 357
f

A. MASSIVE SHALE OF THE GASSAWAY MEMBER OVERHANGING THE
WEAKER BEDS OF UPPER UNIT OF THE DOWELLTOWN MEMBER OF THE
CHATTANOOGA SHALE
The contact is near the middle of the man's hat. The light-colored band, which isabout 0.6 toot below the overhang, is the Center Hill bentonite bed. Locality 95.
1952.

C. CENTER HILL BENTONITE BED IN UPPER UNIT OF THE DOWELLTOWNOF THE CHATTANOOGA SHALE
The bentonite is the light band near the middle of the hammer handle and is here
about 0.6 foot below the base of the overhanging Gassaway member. Locality 95.
1952.

'.

PLATE 9-"B. GRAY CLAYSTONE AND BLACK SHALE BEDS OF
MT OF THEDOWELLTOWN MEMBER OF THE CHATTANOOGA SHALE
Note that black shale is more abundant in the upper and lower parts of the unit.
Moisture and light conditions caused some black beds to appear white,- especiallyin the upper part of the picture. Top of 6-foot rule is at the Center Hill bentonite
bed, which is here 1.15 feet below top of the Dowelltown member. Massive blackshale, here appearing light colored, is at top of picture. Locality 70. 1950.

D. MINUTE LAMINAE OF SILTSTONE IN SAWED BLOCK
OF MASSIVE BLACK SHALE OF THE GASSAWAYMEMBER
Specimen is from the adit (loc. 79) near east approach toabandoned Sligo bridge, De Kalb County, Tenn.

19

CHATTANOOGA SHALE

central Tennessee is largely post-Kinderhookian, or in otherwords almost if not entirely of Osagian age. In addition, it ishighly probable that southward in Alabama it may be of ayounger age, Warsaw and possibly even St. Louis.

Stockdale (1939) apparently held similar views on
the age and stratigraphic relations of the Chattanooga
shale.
Campbell (1946, p. 883-848) called attention to thesmall brachiopod Schizobolus in the lowest beds of theblack shale sequence that Pohl (1930) had named theTrousdale shale; he also identified the beds in Sunnier
and Trousdale Counties, Tenn., and Alien County, Ky.
He assigned them to the Middle Devonian. Campbell
divided the rest of the black shale into his Dowelltown
formation, which he considered to be of Late Devonian
age, and his Gassaway formation of Mississippian age.
He based his age determinations on the presence ofBarroisella n. sp. and Spathiocaris in the Dowelltown
and of Lingula melie in the Gassaway. He also attempted to correlate by lithologic characteristics thedifferent parts of the formation in Tennessee with theunits he had recognized and dated in Kentucky andIndiana.
In the years just preceding our investigations a Mississippian age was generally accepted for much or allof the Chattanooga shale in Tennessee and nearby
areas, as illustrated by the report on the "Correlationof the Mississippian formations of North America"(Weller and others, 1948, especially chart 5, cols. 86-89
and 92-97).
FOSSILS
PLANT MATTER

Many plant and animal fossils are present in the
shale, but few are of types that have been widely used
for age determinations. Plant remains are much themost abundant and are responsible for the dark colorof the shale, but most of them are so degraded and insuch minute fragments that they are best referred tosimply as carbonaceous matter. Larger plant fossils
are occasionally seen on freshly exposed bedding planes
and are unmistakable. J. M. Schopf of the U.S. Geological Survey (written communication, 1954) identified some of them as CaJMxylon, which came to the sea
as driftwood from land areas. In cross section the large
plant remains appear as thin shiny black layers, commonly only 1 to 2 mm thick but in places as much as
10 to 20 mm thick;' they have been erroneously referred
to as bitumen. Schopf (written communication) examined these layers and stated that they are chiefly
vitrain, the shiny constituent of coal.

An unusually thick layer of plant matter in an outcrop near Nashville (loc. 203B) is half an inch or more
thick and several feet long. When the overlying beds
were removed, the coaly layer was clearly recognizable
as a matted mass of stems and other plant parts. Breger
and Schopf (1955) reported that some of the material
in this layer is CaMixylon and that the bed corresponds
in rank to high-volatile A bituminous coal (see table 9,
page 47, for analyses).
Schopf (written communication, 1953) identified, insamples from various outcrops, parts of the free-floating marine algae Foerstia and Pratosalvinia, both ofwhich are known only from rocks of Devonian age. He
also recognized parts of the algoid plant Phototaxites
and several varieties of spores or sporelike objects
which he assigned to the land-plant genus Tasmanites.
Locally some spores can be seen with the naked eye, butmore commonly they are seen in thin sections preparedfor microscopic study (pi. 5(7). A single specimen fromthe Sligo adit (loc. 79) was provisionally identified by
Schopf as similar to Duisbergia mirabUis, previously
reported only from beds of Middle Devonian age.
The abundant plant debris, which is mainly macerated and unidentifiable fragments, constitutes about
20 percent of the black shale by weight and is theprobable cause of the toughness of the shale, for it fills
all the interstices, cloaks the minute mineral grains, andbinds them all tightly together. The gray claystone
beds of the formation obviously have less plant matterthan the black shale, but thin sections show that they
contain scattered particles of plant matter (pi. 5(7).
CONODONTS

Conodonts of many kinds are common in the shale
but are so small that they are barely visible to the naked
eye. Quantitatively they constitute only a small fraction of 1 percent of the rock. They are phosphatic,
being composed of the fluorine-bearing mineral dahllite (Hass and Lindberg, 1946). Conodonts are the unknown part of an undetermined type of marine animal
that is known to have been bilaterally symmetrical.
These fossils and their stratigraphic relations are discussed in detail in a separate report by Hass (1956),
and the following discussion of them is based entirelyon that work.
Diagnostic conodonts are common in the basal sandstone, but otherwise are relatively scarce in the Dowelltown member. Those that are present suggest that mostof the Dowelltown member should be correlated withthe lower part of the Upper Devonian black shale of
Ohio (Hass, 1953; 1956).
Two conodont species typical of the Dowelltown
member are Palmatolepis unicornis Miller and Young-20

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

quist, and P. subrecta, Miller and Youngquist. P. unicornis is most characteristic of the few feet of the lower
unit of the Dowelltown member, just above the basal
sandstone, but ranges throughout most of the member;
P. subrecta ranges throughout the Dowelltown and into
the basal beds of the overlying Gassaway member. P.
subrecta has been found in collections from the Upper
Devonian Dunkirk shale of New York, the Olentangy
shale of Ohio, and a f aunal zone of the middle divisionof the Arkansas novaculite of Arkansas and Oklahoma.
The Gassaway member contains two distinct conodont faunas. The older of these ranges throughout themember, with the exception of the topmost few feet,and contains the following species, which are considered to be characteristic of the Upper Devonian:AncyrognatJius bifurcata (Ulrich and Bassler)
Palmatodella delicatula (Ulrich and Bassler)
Palmatolepis glabra Ulrich and Bassler
perlobata Ulrich and Bassler
quadrantinodosa Branson and Mehl
subperlobata Branson and Mehl
Polylophodonta confluens (Ulrich and Bassler)

Some or all of these species are present in the lower
part of the Ohio shale (Huron member) in Ohio and
Kentucky; the Blackiston formation of Campbell(1946) in Indiana and Kentucky; the Chattanooga
shale near Huntsville, Ala., from which Holmes (1928)
obtained the conodonts she described; and the so-called
Hardin sandstone at Mount Pleasant, Maury County,
Tenn., from which Ulrich and Bassler (1926) obtained
the conodonts they described. Most of these species arealso known to be present in a faunal zone of the Antrim
shale in Michigan; a f aunal zone in the Woodford shale
in Oklahoma; a f aunal zone of the Chattanooga shale
in northeast Oklahoma and northwest Arkansas; and afaunal zone of the middle unit of the Arkansas novaculite, a formation that crops out in the Ouachita
Mountains of Arkansas and Oklahoma. Some of theabove-listed conodonts have not been recognized incollections from the basal foot or two of the Gassaway
member; those that do range into these lowermost beds
are the ones associated with Palmatolepis subrecta, aspecies that ranges into the underlying Dowelltown
member (Hass, 1956, p. 17).
At many localities in central Tennessee the topmost
beds of the Gassaway contain scattered phosphate
nodules and have a distinctive assemblage of conodonts,
including Hindeodella sp. A, and Spathognathodus
inomatus (Branson and Mehl). These permit a correlation with the upper part of the Ohio shale (Cleveland member) in Ohio and Kentucky, and a part of
the Sanderson formation of Campbell (1946) in In-

diana. These formations are also considered to be of
Late Devonian age.
BONES
Single bones are occasionally seen in the shale andat one place a cluster of bones was found. Where recognized, the bones are generally exposed on vertical outcrop faces where the rock has broken along a joint
plane, and they so resemble phosphate nodules a few
inches in diameter that their true identity often is notrealized until the typical bony structure is observed ona freshly broken piece. Few of the bones have beencollected.
The one cluster of bones that was found in the blackshale (loc. 36, Jackson County) was partially excavated and submitted to the U.S. National Museum for
identification. This assemblage of bones is about 4 feetbelow the top of the Chattanooga shale and about 6 feetbelow the base of the Fort Payne chert. Dr. D. H.
Dunkle (written communication, 1954) of the U.S.
National Museum reported, after examining part ofthe material, that it contained a probable dermal armor
complex of some member of the group of fishes thathas been called the DinicJithys terrelli group. He also
recognized in the collection numerous macerated bones
and scales of the early ray-fin fishes Rhadinichthys
antiquus (Williams) and R. devonicus (Clarke). He
stated further concerning this material:
The Diniclithys terrelli group of arthrodiran fishes includes
a uniquely distinct series of pelagic predators. Specific differentiations within the group are currently very difficult to establish
but unquestioned members appear restricted to beds of Late
Devonian age. They range, in western New York State (D.
magnificus), from the "Conodont Bed" below the Genundawa
limestone upward into the Rhinestreet shale; in Ohio and
Kentucky (D. terrelli, intermedius and curtus) from the zoneof spherical concretions near the base upward to below the topof the Ohio shale; and remains (D. missouriensis and/or rowleyi) have been found in the Grassy Creek shale of Missouri.
As evidenced by clearly reworked bone fragments, etc., thelatest occurrences of these arthrodires in the Ohio section, arefound in the conglomeratic bases of the various sandstonechannels of the Bedford and Berea formations where these havecut down into the underlying Devonian formations. This Late
Devonian age determination is borne out also by the ray-finned
fish remains that are known to occur only in the Rhinestreet
shale of western New York State and in the Ohio shale ofnorthern Ohio upward from the earliest horizon, which is
known to me as the Schaeffer's Bridge Bone Bed on the Huron
River above Milan, Huron County, Ohio.

In 1952 Dunkle collected most of the easily accessiblebones from this outcrop for the U.S. National Museum.
He stated that the bones are from one of the largest
specimens of D. terrelli that has been found. Subsequent study of the collection (Dunkle, oral communication) revealed parts of the lower jaw bones of two
individuals. Maher (Maher and Dunkle, 1955) found21

CHATTANOOGA SHALE

the remains of a pleuropterygian shark preserved in aphosphate nodule in the upper part of the Gassaway
member in Clay County, Tenn.
OTHER FOSSILS

The fossils most commonly noticed in the Chattanooga shale are the prints or phosphatic shells of alinguloid brachiopod, which are fairly abundant atsome outcrops and in certain beds. Unfortunately, thesebrachiopods have little known value in stratigraphic
correlations or in age determinations. The phosphatic
brachiopod Orbiculoidea is also found locally. Other
brachiopod fossils have been found only rarely and, so
far as known, are not of a quality or type suitable forpositive specific identification and age determination.
The small brachiopod Schizdbolus is sparsely present
in the lower part of the formation in beds that Pohl
(1930) termed the Trousdale shale. It was on the basisof this fossil that Cooper and others (1942, p. 1740)
and Campbell (1946, p. 883) assigned the enclosing
beds to the Middle Devonian.
L. G. Henbest (written communication) found a few
poorly preserved Kadiolaria in the phosphate nodules,
where conditions were more favorable for their preservation. Although their remains could hardly be expected to be preserved in recognizable form in the shale,
it is entirely possible that Kadiolaria were continually
among the planktonic population in the upper watersof the Chattanooga sea and that they contributed
unidentifiable material to the shale.
PRESENT VIEWS ON AGE OF THE SHALE

On the basis of an intensive study of the conodonts,
Hass (1953; 1956) concluded that the Chattanooga
shale of Tennessee and nearby areas is of Late Devonian age. Preliminary studies of the plant fossils by
Schopf and of one bone collection by Dunkle supplied
further evidence of a Late Devonian age. Seemingly
these studies of widely different types of fossils havesettled the long-standing controversy as to the age ofthe shale.
Locally the basal beds of the shale may be of Middle
Devonian age, though that age assignment is so uncertain that all those beds are here provisionally assigned
to the Late Devonian. In a later section of this report
it is shown (p. 64) that in a few places a discontinuous
bed of black shale in the Maury formation may be
virtually indistinguishable from black shale of the
Chattanooga but is Mississippian in age. Otherwise,
all the Chattanooga shale in central Tennessee andadjacent parts of adjoining States is of Late Devonianage.

STRATIGRAPHY OF THE CHATTANOOGA SHALE
CLASSIFICATIONS

Writers have been in general agreement as to the baseof the Chattanooga shale at most places because of thewidespread unconformity and the conspicuous contrast
between the distinctive black shale and the older underlying limestones or shales. The Hardin sandstone
member in the southwestern part of the area is generally accepted as a basal unit of the Chattanooga. The
position of the upper contact of the Chattanooga shale
has been placed differently by several authors.
Most descriptions of the formation have noted thephosphate-bearing greenish- or bluish-gray claystoneor sandstone, about 1 to 4 feet thick, immediately above
the black shale; before 1900 it was commonly considered to be a part of the Chattanooga shale. Safford
and Killebrew (1900, p. 104,141,143) were the first to
use the name "Maury green shale" for this unit; they
apparently intended that it should not be considereda part of either the underlying or overlying formation,
but subsequent usage has been inconsistent. Some
writers (Hayes and Ulrich, 1903, p. 2; Galloway, 1919,
p. 55; Jewell, 1931, p. 37-41) have included the Mauryin the Chattanooga; others (Bassler, 1932, p. 143-144;
Stockdale, 1939, p. 49-51; Miser, 1921, p. 24; Campbell,
1946, p. 885-887) have considered the Maury either aseparate formation or the basal member of the overlying formation.
Galloway (1919, p. 55-56) and Jewell (1931, p. 3741) further considered the Chattanooga to have threewidespread subdivisions: The Hardin sandstone at thebase, the black shale, and the Maury green shale, orMaury glauconitic member, at the top.
The unit above the black shale that Hayes considered
the Maury member of the Chattanooga shale, Swartz(1924, p. 24) described as a hard gray shale at the baseof the Fort Payne chert; he proposed that it not be
considered part of the Fort Payne, but be known as the
Glendale shale. Like the Maury, his Glendale shale isonly 2 or 3 feet thick, is between the Chattanooga shale
and Fort Payne chert, and has the distinctive greenishgray hues, phosphate nodules, and glauconite. Because
the names Maury and Glendale appear to be synonymous, and because Maury has priority, the name Glendale should be abandoned.
In much of the eastern part of the area here considered, the black shale sequence is interrupted by amiddle unit several feet thick in which gray beds are asabundant as the black shale, or even more so. This unit
has sometimes been informally called the middle graypart of the Chattanooga, and the more typical blackshale parts of the formation have been termed the22CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

lower black and upper black parts of the formation(table 1). Some workers (for example, Klepser, as
quoted by Stockdale, 1939, p. 50) have thought thatthese three lithologic divisions of the Chattanooga incentral Tennessee can be correlated with the three-folddivision of the Chattanooga in eastern Tennessee andsouthwestern Virginia (Swartz, 1924; 1927; 1929), but
studies by Hass (1956, p. 22,25-26) do not bear out thisbelief.
Mather (1920, p. 19) noted in Sumner County, Tenn.,
two distinct divisions in the Chattanooga shale, separated by an unconformity. He expressed the opinion
that two black shale formations are present, though
he did not propose names for them.
Pohl (1930) thought that the lowermost few feet ofthe shale in Sumner County should be separated fromthe two divisions of Mather, and for that lowest unit
he proposed the name Trousdale shale. He considered

the Trousdale to be of Genesee-Portage (Late Devonian) age, and the two overlying divisions ofMather to be of Mississippian age. Later Cooper andothers (1942) and Campbell (1946) assigned the Trousdale shale to the Middle Devonian.
Campbell (1946, p. 881-884) proposed that the Chattanooga shale of Tennessee be divided into three formations the Trousdale formation of Middle Devonian
age, the Dowelltown formation of Late Devonian age,and the Gassaway formation of Mississippian age. He
traced several smaller units of the Chattanooga shaleand parts of the overlying Maury formation and theircorrelatives over large areas and proposed formal
geographic names for them. In this report Campbell's
terms Dowelltown and Gassaway have been accepted,
the former with some modification. Table 2 compares
Campbell's usage and age assignment with those of thisreport.

TABLE 2. Comparison of stratigrapJiic nomenclature and age assignments of Campbell and of this report
CAMPBELL (1946, P. 880-901)

THIS REPORTFORMATION AND MEMBER

Fort Payne chert
New Providence shale

FORMATION AND MEMBER

Fort Payne chert

New Providence shale or Ridgetop
shale, at least in partMaury shale (basal bed of New Providence
shale or Fort Payne chert)
Maury formation
Westmoreland shale
Eulie shale
Gassaway formation
Bransford sandstone member

Gassaway member
Bransford sandstone bed

Dowelltown formation
Upper Dowelltown
Lower Dowelltown
Hardin sandstone member

1 Campbell assigned no specific rank to the Chattanooga shale; he treated it as superior to a formation but did not Indicate its relation
to a group.
3 Includes Trousdale shale of Pohl (Trousdale formation of Campbell).
8 Present only in southwestern Tennessee and northwestern Alabama; presumed to be of Late Devonian age.

23

CHATTANOOGA SHALE

With the exception of the Trousdale formation andthe Hardin sandstone member, all the subdivisions of
the Chattanooga shale shown in table 2 as used byCampbell were also proposed by Campbell. In thisreport the beds identified as Trousdale by Pohl andCampbell are considered to be a part of the Dowelltown
member of Late Devonian age.
Eather than split into two formations the thin sequence of similar rocks that for so long has been considered one formation, the name Chattanooga shale isretained as the formation name for much the samerocks for which it has been used for over half a century.
Campbell's terms, Dowelltown and Gassaway, are redefined as member names for the units to which heapparently intended to apply them. Along most of
the eastern edge of the Nashville Basin the Dowelltown
can be readily subdivided into two units and the Gassaway into three. In some areas only the Gassaway member is present, in some others both are present, but
nowhere is only the Dowelltown known to be present.
Studies of the conodonts have led to the conclusionthat the Gassaway and Dowelltown members are of
Late Devonian age. For the most part, the two members can be recognized by their physical characteristics
along much of the northern and eastern edges of the
Nashville Basin, in parts of the Sequatchie Valley, andin the cuttings of oil test wells in the intervening Eastern Highland Eim and Cumberland Plateau. Where
the distinctive beds of the upper part of the Dowelltown are absent, the two members can be differentiatedwith certainty only by study of their conodonts.
Campbell's descriptions of his Dowelltown and Gassaway formations at his type localities overlap andinclude a few feet of the same strata in both units(Hass, 1956, p. 13-16). After Campbell did his work,
several nearby deep highway cuts exposed complete
sections of the entire Chattanooga shale beneath asmuch as 50 feet of overburden, and these sections leave
no doubt as to the real succession of beds within theformation.
The Hardin sandstone of Safford and Killebrew(1900), considered by Campbell to be a basal memberof his Dowelltown formation, is here treated as amember of the Chattanooga shale. The Hardin grades
upward into the Dowelltown member and is restricted,
geographically, to the vicinity of Hardin, Wayne, andPerry Counties, Tenn. (fig. 6).
The Bransford sandstone member of Campbell is aneasily recognized sandstone, commonly 3 inches or lessthick, at the base of the Gassaway member along thenorthwestern edge of the Nashville Basin. It is referred
to in this report as the Bransford sandstone bed.

In the early part of the work for this report, theseveral stratigraphic units were referred to by descriptive lithologic terms. These informal terms were usedin various administrative reports, field conferences, andcorrespondence and have consequently appeared inseveral reports by other workers. After 1952 the moreformal terms were used (table 1, p. 6).
SUGGESTED STANDARD LOCALITY

Two of the best and most accessible of the new exposures of Chattanooga shale are along the approaches
to the new Sligo bridge over the recently impounded
waters of Center Hill Eeservoir, in DeKalb County,
about 6 and 7 miles east of the courthouse at Smithville along Tennessee Eoute 26 (loc. 76, 82). These
excellent exposures are only about 11 and 18 miles eastof the Dowelltown and Gassaway type localities, andthe eastern one (loc. 76) is here used as a standard
locality in redefining the Dowelltown and the Gassaway as members of the Chattanooga. At the eastern
locality the formation is well exposed in clear-cut association with the overlying and underlying rocks, andall the characteristic features of Campbell's localities
are present. This Sligo outcrop is diagrammed infigure 5.
After completion of fieldwork, the entire Chattanooga and Maury sequence was well exposed 5.8
miles west of Smithville in an unusually deep cut for a
new highway leading off the Highland Eim. This outcrop is only about a mile from the type locality ofCampbell's Dowelltown formation and shows virtually
the same stratigraphic section as the one at our standard locality. If it had been exposed earlier, it would
very likely have been chosen as the standard locality.
Other equally good exposures show the same stratigraphic section and would have been excellent standard
localities. The Sligo one was chosen because of its
proximity to Campbell's localities, and because it shows
promise of remaining well exposed and accessible for along time.
BASAL SANDSTONEAt most outcrops a basal bed of sandstone is about
0.1 foot thick, or less, but locally is thicker and exceptionally is as much as 3 feet thick, especially along
the Western Highland Eim and in the western valleyof the Tennessee Eiver. It commonly contains abundant detrital fragments of quartz, chert, conodonts,
phosphate, shells, and bones. The sandstone is a typical basal conglomerate in miniature, containing thecoarser fragments of the material that was on the
nearby land surface at the time of inundation by thesea, together with fragments of animals that inhabitated the sea. In a few places a thin bed of black shale

24

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

FORMATION
THICKNESSSYSTEM SERIES GROUP (THICKNESS, MEMBERSECTIONIN FEETL IN FEET)
Fort Paynec
3Z(O^T^^i^hffi??
chert
0
<
.
Q.
200 +
CC
Q.
200-1Oi .°^M'^liAVH
CARBONIFI LMISSISSIF
o .2
Maury
i in
V)
1.9±
formation
2
2.3
D
V
E
1
N
0
AN

^ "

TI^

:
o>
-Q

\0.4±\

Q.
Q.

=s^
=5

E
o>
E

"" "****^"

V
^^^

c

>>

(O

I

6.9

^^

HMMM^

2.3
====^=

CO==S==i^====
^=
=

5
(O

c

V)

in

o

ro
O

>

;
o

SSS(MSiSSi^SSSS5SB^^S
-^
' «^
-1

7.5

_l

-

Chattanooga
shale

Q)

Q

32.1

__

^
sag

CHARACTER

OF

ROCKS

Interbedded chert and limestone; greenish-gray to grayish-yellow
bedded chert and greenish-gray dense argillaceous siliceous
Claystone and scattered phosphate. Claystone is light to medium
bluish gray (fresh), grayish yellow green to dark yellowish orange(weathered); has blocky to subconchoidal fracture. Phosphatein form of balls, disks, and plates; balls and disks less than 0.1
foot ir> diameter; plates less than 0.5 foot in greatest dimension;
most abundant at top and base. Top contact is sharp and undulating having 0.1 foot relief.

Phosphate nodule layer of variable thickness. Nodules of many
shapes as much as 1.5 feet or more in greatest dimension, in an
olive-gray sandy matrix. Concentration of nodules varies laterally.
Where nodule layer is thickest, overlying claystone iscorrespondingly thinner.
Black shale.
Scattered phosphate nodules in upper 0.4 foot.
Unweathered rock is grayish black, massive, and breaks withconchoidal fracture; weathered rock is medium to dark gray andfinely fissile. Paper-thin medium dark-gray siltstone partings;
films and thin lenses of marcasite.
N
Interbedded black shale and medium-gray claystone. Chiefly blackshale as described in overlying unit. At base is a "varved bed"
approximately 0.05 to 0.20 foot thick consisting of thin alternating beds of light-brown siitstone and black shale; the blackshale layers become thicker and more closely spaced upward.
Basal contact sharp.

\

Black shale.
Similar to 6.9-foot black shale unit above. A few
thin layers of medium-gray claystone near base, suggesting thatlower contact is gradational.

5f55SES5wHEEEssEM555l

05
-Q

o>

E
o>

E-

Q.

Q.

c

13

Q)

9.2

Interbedded medium light-gray claystone and dark-gray shale beds
commonly 0.1 to 0.4 foot thick. Bentonite bed, 0.09 foot thick,has conspicuous biotite flakes; olive gray where fresh, paleyellowish orange where weathered and readily observed on faceof outcrop; top is 0.85 foot below top of unit.

6.2

Black shale. Generally resembles 6.9-foot shale unit above, color
ranging from grayish black to dark gray.
Poorly sorted basal
sandstone present at most places. Averages about 0.02 footthick; contains very fine grained clear quartz, iron sulfide, waterworn chert and shell fragments, and conodonts. Basal contact
sharp but slightly undulating, truncating underlying limestone atan angle of 1° or less.

Q.

:^=s=!==^^»^^=B=sas^g
=g*

5
o

Q)

z
<
o

5Q
CC

o>

5

5

o

o

Q

_i

J-1-t-r ! i ' T ' i ' i ' i ' i ' i -H-C, <oMiddk Ordovici

o>
£
>>
(C

Leipers
limestone
50±

i ; i ; i ; ! ; i ; 1 ; i ; i ; 1 ; ! ;Limestone, bluish-gray, and argillaceous; light-gray to bluish-graycalcareous siltstone in lower 30 feet. Weathers grayish orange
to yellowish gray.

o
FIGURE 5. Standard section of the Dowelltown and Gassaway members of the Chattanooga shale. Vertical cut along east approach to Sligo
bridge on State Route 26 (loc. 76), about 7 miles east of Smithville, DeKalb County, Tenn.

25

CHATTANOOGA SHALE

is enclosed within the sandstone or lies beneath it, acondition that is referred to in the later discussion of
the origin of the shale (p. 53).
Three local but striking f acies variations in the composition of the sandstone in Tennessee are noteworthy.
In each case the variation results from special conditions that existed on the pre-Chattanooga land surface at the time it was submerged.
One of these is in the Flynn Creek cryptoexplosive
area. Here the strongly shattered and even pulverized
limestones were locally reworked, probably into low
places on a somewhat more uneven surface than existed
generally throughout the region. These local accumulations, reported to be as much as 10 or 20 feet thick,have been referred to by Wilson and Born (1936, p.
821-822) as "bedded breccia" and by Conrad and others(1957, p. 16) as a "fresh-water" limestone. The discovery by Hass (see p. 11) of the lower Upper
Devonian conodonts in this limestone indicates that it
was deposited at the beginning of Chattanooga time ina marine environment. In this unusual situation, themost available material that could be reworked into abasal sandstone was the shattered limestone. The result
is a facies of the basal sandstone that, so far as weknow, is unique in the formation.
Another unusual type of the basal sandstone is close
to the Jackson-Clay County line, along the road that
follows Hudson Creek, 4V4 miles northwest of the community of North Springs in Jackson County and 334
miles southeast of Red Boiling Springs, which is in
Macon County (loc. 210). Here the Chattanooga shalelies with an angular unconformity of about 5 degrees
on a few feet of calcareous shale and quartzitic sandstone. Differential erosion of these strata has produced
an irregular surface having a foot or more of relief.
The quartzitic sandstone, which forms a miniature
cuesta, has yielded many waterworn slabs as much as 6
inches in length. These slabs are embedded in a coarse
sandstone as much as a foot or more thick. Obviously
the low parts of this surface were gathering places forthe coarse detritus, much of which is obviously of very
local origin. Of additional interest at this place is thepresence of two layers of black shale, each about half
an inch thick, within the gravelly sandstone.
The third unusual type of basal sandstone is widespread in the Swan Creek phosphate field of Lewis andHickman Counties and in nearby parts of Perry and
Maury Counties. Here an unusually thick sandstone
at the base of either the thin Chattanooga shale or,where that is absent, at the base of the Maury formation
contains a considerable percentage of phosphate. Thisunit, which is 1 to 2 feet thick, was once mined as "bluephosphate." It has been incorrectly considered cor-

relative with the Hardin sandstone member. The "bluephosphate" is a coarse basal sandstone consisting largely of reworked residual phosphate from the Leipers
limestone. The phosphate is in the form of bluishblack ovules and phosphatized fragments of fossils
from the Leipers. Smith and Whitlatch (1940, p. 301310) described the phosphate more fully and summarized the theories of previous writers regarding its
origin.
At some places the sandstone is absent, and massive
black shale of the Chattanooga rests directly on theunderlying rock, though at most places diligent search
reveals small separated patches of the sandstone.
The age of the sandstone ranges from earliest Late
Devonian to earliest Mississippian, for the encroachingsea reached different areas at widely different times.
Where the Dowelltown member is absent and some partof the Gassaway member is the lowest shale present,
the sandstone is of Gassaway age. At places where theentire Chattanooga shale is absent, a similar sandstone
at the base of the Maury formation is presumed by us
to be of very late Devonian or of Early Mississippianage, though nowhere has Hass found conodonts in thesandstone younger than those characteristic of the
Gassaway member of the Chattanooga shale. Most of
the conodonts in the basal sandstone are fragments,
but Hass identified a sufficient number to determinethat at most places the sandstone is closely related inage to the beds that lie immediately above it.
This range in age of the basal sandstone has contributed greatly to the long-standing disagreements
over the age of the Chattanooga shale, for in the vicinity of Mount Pleasant, Tenn., where Chattanooga
shale is absent and the sandstone is at the base of theMaury formation, it has supplied many of the fbssils
that Ulrich and Bassler (see Bassler, 1932, p. 137) used
to "prove" the Mississippian age of the Chattanooga
shale. In the Mount Pleasant area, however, Hass
identified a number of conodonts in this sandstone andassigned its age to Late Devonian, or Gassaway.
HARDIN SANDSTONE MEMBERThe name Hardin sandstone was used by Safford andKillebrew (1900, p. 104, 136, 137) for a fine-grainedsandstone at the base of the black shale in much of
Hardin, Wayne, and Perry Counties and in parts ofsome of the nearby counties. The unit was named forthe county, but no type section was designated. Safford
and Killebrew treated it as a separate formation but
stated there were reasons for considering the Hardin
as part of the Chattanooga shale. Subsequently it hascommonly been considered a member of the Chattanooga.

26

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

87°00'

87° 30'

0 00'

36 "DO-EXPLANATION
10

5 'Lines of equal thickness, in feet
J 10o

TENNESSEEHUMPHREYS

2.6

Localities showing thickness of outcrop, in feet. Solid circles by present
authors; open circles by others
Source of outcrop data by others
D Dunbar(1919)
H Hayes(1896)
J Jewell(1931)
Ml Miser (1921)
MO Morse (1930)

35'
30'

ECATlURiL\AWR\ENCEL"GILES

35'
00' I

TENN
MISS M0 0}.3

TENNESSEEALABAMA

!

MO 0

Y ^

TISHOM INGO

1

LAUDERDALEN

LIMESTONE-0

1 COLBERT V

/

.

X
10

LAWRENCE
10V
20 MILESFIGURE 6. Thickness and distribution of the Hardin sandstone member of the Chattanooga shale.

CHATTANOOGA SHALE

27

The sandstone is massive and is so fine grained thatmuch of it could equally well be termed a siltstone. It
is somewhat phosphatic, contains pyrite spherulites andconcretions as much as 0.5 foot in diameter, and is very
light to dark gray when fresh. When weathered it
commonly has colors close to grayish yellow (5 Y 8/4).
At most places the rock is so firmly cemented with silica
that it breaks across the quartz grains; at some localities it has a calcareous cement. The sandstone is slightly coarser at the base, where it has a few scattered sandgrains as much as 2 mm in diameter and a few scattered phosphate nodules. Fossils are scarce.
The distribution and thickness of the Hardin sandstone member are shown in figure 6.
The thickest known exposures of the Hardin sandstone member are near Olivehill in Hardin County
where Dunbar (1919, p. 91,119-120) and Jewell (1931,
p. 39) reported it to be 16 feet thick. A 15-foot ledgeof the sandstone crops out along U. S. Highway 64 at
the east edge of Olivehill (loc. 238).
At Olivehill (loc. 239) an unbroken sequence shows
the sandstone of the Hardin member grading upward
through a 12-foot interval of alternating beds of finesandstone and shale into the black shale of the Dowelltown member. Such an upward gradation of the sandstone into the shale is common in the general area of
Hardin County. The Olivehill exposure is described in
the following section.

At some places, as in southwestern Lawrence County,
the Hardin sandstone member is separated by a knifesharp contact from overlying black shale of Gassaway
age. In central and northern Wayne County blackshale is absent and the Hardin is overlain directly by
the Maury formation, as illustrated by the following
section of an outcrop half a mile north of Waynesboroon the west side of Tennessee Eoute 13 (loc. 243).

Section near stone church at Olivehill, Tenn.

An excellent exposure of the Hardin sandstone member is at locality 241 in Wayne County, where it is
exposed for about a quarter of a mile along a country
road that follows Indian Creek. Here 8 feet of sandstone is overlain abruptly by about 8.5 feet of poorly
exposed Chattanooga shale, which in turn is overlain
by about 2 feet of the Maury formation having olivegray claystone in its lower half and glauconite andphosphate nodules in its upper half.
Campbell (1946, p. 892-894) summarized the viewsof several previous workers regarding the Hardinsandstone member and its lateral equivalents; he accepted the earlier views of Hayes (1896, p. 521), Bassler (1932, p. 139), and Hayes and Ulrich (1903, p. 2)that it merges laterally to the north into a shaley phosphate that is present at the base of the "blue phosphate"at many places in Perry County and in the Swan
Creek phosphate area of Lewis and Hickman Counties.
Although we have not studied the phosphate area in asmuch detail as did Hayes, we are strongly of theopinion that the Hardin does not merge laterally intothe "blue phosphate" because at no place did we observea lateral merging and because the Hardin appears to beof early Dowelltown age whereas the "blue phosphate"

Maury formation:
Siltstone having glauconite, sulfide nodules, andabundant phosphate; poorly exposed; about___
Chattanooga shale:
Gassaway member:
Shale, black; weathered and partially concealed;
about _______________________
Dowelltown member:
Shale, medium-gray to dark-gray; some interbeds of very fine sandstone or siltstone; contains Palmatolepis unicornis ________________
Shale, black to dark-gray; contains Palmatolepis
unicornis __________________________________
Shale, dark-gray; alternates with siltstone andvery fine sandstone _______________
Hardin sandstone member:
Sandstone and siltstone, gray and brown; massive ; exposed in road ditch ___________
Sandstone, poorly exposed near creek; base ofunit not exposed; about_____________

Feet

Total Chattanooga shale, about ______

48.0

1

4.5

11.3
7.5
12.

2.7
10.

The presence of the conodont Palmatolepis unicornis
indicates that the black shale into which the sandstone
grades belongs to the Dowelltown member.
553638 61

3

Section half a mile north of Waynesboro, Tenn.
Fort Payne chert and Ridgetop(?) shale.
Maury formation:
Siltstone; various shades of orange and brown; nonglauconitic at top, but increasingly glauconitic
toward base, where it is abundant in lowest 0.1
foot _____________________________
Siltstone; various shades of gray; glauconite moreabundant toward base; laminated. Lowest 0.3 footcontains many phosphate nodules and the following
conodonts indicative of a Kinderhook age: Gnathodus sp. B, Gr. sp. fragments, Spathoffnathodus aciedentatus, Pseudopolygnathus prima, Siphonodellasp. fragments, Polygnathus communis, P. inornata

Feet

Total Maury formation ______________
Chattanooga shale:
Hardin sandstone member:
Sandstone, light-gray, massive; very fine grained
at top, but a somewhat coarser below; basal
contact somewhat undulating; about _Limestone.

4.3

2.1

1.2

13.7

28

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

of upper Swan Creek is of late Gassaway or possibly
even of Maury age. The "blue phosphate" is a basal
conglomerate or sandstone of whatever part of the
Chattanooga-Maury sequence was first deposited on aland surface strewn with residual phosphate.
Our investigations confirmed Campbell's opinion(1946, p. 894) that the thin sandstone at the base of the
Chattanooga shale throughout the area should not be
considered the Hardin sandstone member, as has been
done by some writers (for example, Galloway, 1919, p.
55; Bassler, 1932, p. 138-139). The Hardin is an abnormally thick local phase of the basal sandstone, andthe name should be reserved for the distinctive quartzitic and massive very fine sandstone or siltstone of thearea in and near Hardin and Wayne Counties (fig. 6).
However, the thin basal sandstone or conglomerate,present nearly everywhere at the base of the Chattanooga shale, is quite variable in composition andranges in age as much as the next overlying material.
The Hardin grades upward, locally, only into theDowelltown; the ubiquitous basal sandstone grades upward into whatever unit overlies it.
No conodonts have been found in the Hardin sandstone member but, because the Hardin grades upward
at some places into the lower part of the Dowelltown
member, it is considered to be of early Late Devonianage. It is possible, however, that a part of the Hardinsandstone member may be slightly older.
Complete exposures of the Hardin sandstone member
and the overlying beds of the Chattanooga shale andMaury formation are not common, so interpretationof the relations of the Hardin sandstone member to theoverlying beds is not easy. The following interpretation is, therefore, based on fragmentary evidence andis not as well documented as could be wished.
In at least part of Hardin County (for example, loc.
239) sedimentation obviously was more or less continuous from the Hardin sandstone member into theoverlying Dowelltown member, and it is probable thata continuous sequence existed elsewhere, but at mostplaces no transitional sequence is now present. Sedimentation was interrupted, probably at the end of
Dowelltown time, and the muds and gradational bedsof the Dowelltown member, and perhaps some of theHardin sandstone member, were removed before muds,of the Gassaway were deposited. In many of theseplaces, black shale of the Gassaway member overlies
the Hardin sandstone member. In still other places, theGassaway beds are also missing, either because the area
was not inundated during Gassaway time or because
the muds were removed by a post-Gassaway pre-Maury
erosion interval.

DOWMLLTOWN MEMBER
LITHOLOGIC CHARACTER

The Dowelltown member of the Chattanooga shale islithologically most distinct along the eastern edge of
the Nashville Basin. There it contains a lower unit,
chiefly of black shale, and an upper unit of abundant
beds of gray claystone interbedded with black shale.
Because the lighter color of the upper unit contrasts
with the black shale of the rest of the formation theunit has been noted frequently by previous workers
and has sometimes been referred to as middle gray unitof the Chattanooga (table 1). Throughout most of theEastern Highland Rim area and in some other areas
where the gray claystone unit is present, a distinctive
thin bed of bentonite near the top is most useful for
identification and correlation of the beds (pis. 6.Z?, 8).
Where the Dowelltown member has been identified
but where the two lithologic units are not distinct, themember consists chiefly of dark-gray or medium-darkgray shale. Commonly this shale is less dense and massive than the black shale of the overlying Gassaway
member, and in vertical exposures it breaks down more
readily when weathered (pi. 6J.). This undivided
phase of the Dowelltown member is especially characteristic along the northern edge of the Nashville Basinfrom the general vicinity of the Cumberland River inJackson County to the Nashville area, but in thoseplaces the Dowelltown member can be differentiatedfrom the Gassaway by its lithologic character, its differential weathering, and its conodonts.
In the central part of the northern edge of the Nashville Basin the lower few feet of the Dowelltown member is composed of several layers of calcareous siltstone
and black shale that Pohl (1930) defined as the Trousdale shale (p. 22). Pohl did not designate a type
locality for this unit, but one of the most accessible
exposures of these beds is locality 206 in Sumner
County, where about 2 feet of the calcareous sandy
shale is present. We do not consider the unit sufficiently
distinct lithologically or of sufficient areal extent towarrant member status.
EXTENT AND THICKNESSThe Dowelltown member is consistently present
along the eastern edge of the Nashville Basin as far
south as Moore County, along the northern edge of thebasin, and along the western edge as far south as
southern Williamson County. It is also present in Kentucky, and in the northern part of the Sequatchie
Valley in Tennessee (pis. 7, 8). It is not a recognizable
lithologic unit near the southern edge of Tennessee orin the States farther south, though Hass (oral communication) identified conodonts of Dowelltown age

CHATTANOOGA SHALE

from rock as much as 2.2 feet above the base of the
Chattanooga shale at locality 230, near Menlo, Ga., andin the lower 7 feet of the exposed beds at locality 235
in northeastern Mississippi. As pointed out by Glover(1959, p. 13) in discussing the eastern part of thissouthern area, lithologic differences are insufficient towarrant splitting the formation into members, and theterms Dowelltown and Gassaway are useful in a timesense only.
Along much of the eastern edge of the Basin the
Dowelltown member is commonly about 15 to 20 feetthick. At some places near the northeast corner of the
Nashville Basin, as at localities 16, 22, and 25, themember is a single unit about 5 feet thick, or less.
Along most of the northern edge of the basin the
Dowelltown is about 15 to 20 feet thick. The thickness of this member differs more between nearby outcrops than does the thickness of the Gassaway member,probably because of slight irregularities on the land
surface when it was inundated by the Chattanooga sea.
The diamond-drill cores taken in 1953 near Smithville, DeKalb County, at intervals of about 1 mile, show
a slight thinning of both members of the Chattanooga
shale toward the Nashville Basin. In the Dowelltown
member this thinning amounts to about 3 feet in an eastwest distance of 15 miles (figs. 9,10).
LOWER AND UPPER CONTACTS

Except at those places where the Hardin sandstone
member underlies the Dowelltown member, the lower
contact of the Dowelltown is also the basal contact of
the Chattanooga shale. Commonly the position of thiscontact is easy to identify.
The upper contact of the Dowelltown member is the
only pronounced and continuous lithologic break in
the Chattanooga shale. Along much of the eastern edgeof the Nashville Basin the break is fairly conspicuous
in most good outcrops, but it is difficult to locate precisely because two or three thin beds of gray claystone
are present in the lower half foot of the overlying
Gassaway member. In that area the contact can be
identified fairly consistently at the base of the lowest
massive black shale bed within the doubtful interval.
Below that horizon the rock is predominantly grayclaystone; above, it is predominantly black shale. In
most other areas the contact is fairly sharp and can befound with ease, for example, in eastern Sumner
County (loc. 206) where Mather (1920, p. 19) noted aslight angular unconformity.
The contact between the Dowelltown and Gassaway
members in some areas marks a diastem or slight unconformity within the Chattanooga shale, probably the
result of submarine erosion or planation before themuds of the Gassaway member began to accumulate.

29

The best observed examples are in the Woodbury area
(fig. 8), where the bentonite and associated beds appear
to have been removed before Gassaway time, and at
Bransford (loc. 206) where a slight angular discordance separates the two members. The thin bed ofBransford sandstone at the base of the Gassaway member at many places also suggests the presence of a slight
unconformity at this position. The widespread presenceof the thin Center Hill bentonite bed, however, in theupper 2 feet of the Dowelltown member is evidence
against any appreciable erosion at the end of Dowelltown time. Mention has already been made (p. 28)
of probable erosion of some of the beds at the end of
Dowelltown time in areas where the Hardin sandstone
member is present.
LOWER UNIT
General characteristics. The lower unit of the
Dowelltown member is one of the several characteristic
black shale units of the Chattanooga shale, and, likethose others, it emits a distinct odor of petroleum whenbroken. When fresh it is firm and strong and tends tobreak with a conchoidal fracture; when weathered it
crumbles into thin wafers (pi. 105). Scattered throughout the unit are paper-thin partings of siltstone; discontinuous thin lenses or films of sandstone; thin films,
lenses, and crystals of pyrite or marcasite; and a few
beds of somewhat lighter colored claystone 0.02 footthick or less. This unit is similar to the massive blackshale of the Gassaway member except that it contains
more thin beds of other material, is somewhat less massive where fresh, and is slightly less radioactive (fig.
18). Petrographic examination shows that the freshrock is minutely laminated, most of the grains being inthe size range of silt and clay.
A bed of sandstone that is present at most places atthe base of the Dowelltown member ranges in thickness
from zero to several inches but commonly is an inch orless thick. This, in turn, rests unconf ormably on theolder rocks, which, at most places, are of Ordovician
or Silurian age.
The contact of the lower unit of the Dowelltown withthe overlying gray claystone unit is somewhat gradational but can generally be located without much difficulty within half a foot or less.
Extent and thickness. Except locally, as in the areaof the Hardin sandstone member, the lower unit of the
Dowelltown member is not as widely distributed as aremost of the higher black shales, presumably because
the Chattanooga sea did not flood as wide an area during early Dowelltown time. It is absent in much ofsouthern Tennessee and in much of the area west of thebasin. Black shale of the Dowelltown has been identified at several scattered outcrops in the region where;30

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

it is generally absent, but there is no basis for correlating it specifically with either unit of the Dowelltown
member as they are recognized along the eastern edgeof the basin.
Except near its lateral limits, the lower unit of the
Dowelltown member is commonly about 5 to 9 feetthick. At a few places it is somewhat thicker, probably
because of low places on the old land surface, as at
locality 80 where a poor outcrop shows about 13 feet.
In the Flynn Creek cryptoexplosive area the unit is as
much as 170 feet thick, probably because the sea floor
at that place subsided as the muds accumulated (p. 12).
T7PPEB UNIT

General characteristics.
The upper unit of the
Dowelltown member consists of an interbedded succession of light-gray to dark-gray claystone and blackshale, the gray beds predominating. Although bothtypes of beds vary in thickness, most of the individual
black and gray beds are a few inches thick. Along thecentral part of the Eastern Highland Rim, the graybeds are much more abundant in the middle of the unit,
and the black shale beds are more abundant toward thelower and upper contacts. The gray beds are not as
tough and massive as the black shale, probably because
little organic matter is present to bind the particles.
On weathering in vertical exposures, the unit recedes
and leaves the black shale of the Gassaway member
overhanging (pis. 65, 9 A). The general appearance of
this unit is shown on plate 95. It is the most distinctiveof the several subdivisions of the Chattanooga shale
and forms a conspicuous break in an otherwise fairly
uniform sequence of black shale that normally constitutes the Chattanooga shale. It is the unit that has
sometimes been informally termed the middle gray unitof the Chattanooga.
This unit of abundant gray claystone is easily
recognized along the eastern edge of the basin fromsouthern Jackson County to southern Coffee County.
It also crops out in southeastern Williamson County(loc. 185, also p. 63) and in parts of the Sequatchie
Valley of Tennessee.
Microscopic study of thin sections of the beds of grayclaystone and black shale of this unit shows that thegray beds are somewhat finer grained and more clayey
than the black shale beds. The gray beds are poorly
laminated and appear to consist of about 50 to 75 percent clay, 10 to 20 percent quartz, and smaller amountsof very fine mica, pyrite, calcite, and organic matter.
The mineral grains are poorly sorted and their longaxes show imperfect parallelism. The quartz grains are
exceedingly small, ranging roughly from 0.008 to 0.065

mm and averaging about 0.02 mm in diameter. The
flakey clay grains are much smaller, their lengths being
typically about one-half to one-third the dimensionsof the quartz grains.
The grains in the black shale that is interbedded withthe claystone are somewhat better sorted than those in
the gray claystone but not as well sorted as those in
the more massive black shales of the Gassaway member. The quartz grains in the black layers have an
average diameter of about 0.01 to 0.02 mm. Pyrite isabundant as minute grains ranging from about 0.01 to
1.0 mm. The lack of sorting and the somewhat randomorientation of the grains in the gray beds probably
explain the absence of fissility of these beds. The blackshale beds in this unit are somewhat fissile when
weathered but less so than those in most of the blackshale of the formation.
Bentonite. A thin bed of bentonite, discovered by
Hass (1948), near the top of the Dowelltown memberof the Chattanooga shale, is the most distinctive single
bed in the entire formation and has been of much value
in stratigraphic work. The bed commonly ranges inthickness from about 0.05 to about 0.14 foot and in mostoutcrops is about 0.1 foot thick. In general, the bed isslightly thicker toward the east. Wherever it was observed it is within 2 feet of the top of the Dowelltown
member, and no similar bed was found elsewhere in theformation. This bentonite clearly represents a single
fall of volcanic ash and is, therefore, a useful time
marker. It is here designated the Center Hill bentonite
bed because of its presence at all known outcrops of
the Chattanooga shale that are adequately exposed near
the Center Hill Reservoir in DeKalb, Putnam, andWhite Counties, Tenn. Its type exposure is at the
proposed standard locality of the Chattanooga shalealong the east approach to the Sligo bridge in DeKalb
County (fig. 5).
Unweathered samples of the bentonite are light gray(N 6) but are commonly found only in new deep highway cuts, some waterfalls, and drill holes. Flakes ofeuhedral biotite are easily seen in the fresh material.
Weathering quickly bleaches the biotite and causes the
bed to be much lighter colored and faintly iron stained,
so that its typical color in most road cuts after a few
years' exposure is about yellowish orange (10 YR 7/6),
though in some places it is even paler, approaching avery pale orange (10 YR 8/2). The bentonite bed,
where more weathered, appears as a slightly recessedbut conspicuous yellowish-red bed across the face ofthe outcrop (pi. 9.A, C). Once this distinctive bed has
been seen in one outcrop, it is easily recognized inothers.

CHATTANOOGA SHALE

Clarence S. Koss, of the U.S. Geological Survey,
examined a fresh sample of the bentonite and found(Hass, 1948) that
* * * all or nearly all of the material is of volcanic origin andthat the groundmass consists of clay whose indices of refraction
indicate that it is the potash type of bentonite. This is confirmed by chemical tests that indicate essential amounts ofpotash. A detailed study of material from Horseshoe Bend, on
Caney Fork River, White County [locality 88, now submergedby the Center Hill Reservoir], indicates that fresh material
contains about 30 percent of biotite, some as euhedral grains.
Other crystal grains form about 8 percent of the whole. Of
these about 49 percent are orthoclase, about 43 percent sodic
plagioclase, and about 8 percent quartz. Thus the mineral composition is typically that of a volcanic rock. The clay groundmass was probably originally a glass.
* * * The clay fraction resembles, and the biotite is similar
to, that present in most Ordovician bentonites. * * * The mostweathered portion of the bed is nearly white and * * * consistsof kaolinitic clay, quartz, and abundant bleached biotite.

This is the youngest known deposit of the Ordovician
type of bentonite (Koss, written communication, 1948).
More detailed studies were made at Pennsylvania
State University (Strahl and others, 1954, p. 7-9) of
samples of fresh and weathered bentonite. These indicate that the dark mica, when weathered, is bleached
and altered to kaolinite.
At most outcrops of the Chattanooga shale along theeast side of the Nashville Basin from southern Jackson
County to central Coffee County, a distance of about
65 miles, the bentonite bed is found wherever that partof the shale sequence is exposed^2 It has also been foundin the Sequatchie Valley of Tennessee and at one placein the western part of the basin (loc. 185, see p. 63)
and was found by Hass and W. H. Heck (written
communication, 1948) in the cuttings of several oil test
wells in Putnam, White, and Van Buren Counties, on
the Eastern Highland Kirn. We made further checksof cuttings from wells in Warren, Grundy, Van Buren,
Cumberland, Putnam, Overton, and Fentress Counties,
in areas adjacent to the then known limit of distribution, and the bentonite was not observed.
The bentonite bed is generally present in an area in
Tennessee of at least 4,000 square miles (pi. 7, fig. 7),
but it is missing in one small area of about 100 square
miles in the northern part of Cannon County. It is
possible that the uppermost beds of the Dowelltown
member were never deposited in this area, but it seems
more likely that those beds were removed before thebeginning of Gassaway time. At the nearby outcrops
where the bentonite is present it is much closer to the
top of the Dowelltown member than at more distant2 Hass (1948) reported the bentonite as being present still farther
south near the Bedford-Lincoln County line, on the basis of an observation by Conant. Later observations indicate the bentonite is notpresent at that outcrop.

31

places. It is unlikely that the area was elevated above
sea level just enough to permit the removal of only a
few feet of the upper unit of the Dowelltown without
producing an irregular erosion surface or any signsof subaerial weathering. More likely, local conditions
caused the sea water to plane the area gently and transport the unconsolidated gray and black muds to nearby
areas. A slight upwarp of the sea bottom would
probably have sufficed to cause the removal of thismaterial. The amount of uplift required may have been
not much greater than the thickness of the missing
sediments. It is possible, of course, that other local
conditions caused currents or wave action strong
enough for the indicated planation, though local upwarp seems to us to be the simplest explanation of themissing beds.
The presence of this bentonite bed, which is an excellent time datum, supports Hass' opinions on the age
correlation of the Chattanooga shale as based on conodont studies and is strong evidence against the thesisthat the black shale sequence is a time-transgressing
unit that is youngest in the southern States. The stratigraphic ranges of conodont genera and species were
found by Hass to be constant with reference to theCenter Hill bentonite bed, an excellent confirmation of
the dependability of conodonts in regional correlations.
The source of the ash is unknown, but the fairly
uniform thickness that increases slightly toward theeast suggests that it was at a considerable distance in aneasterly direction. The uniform thickness and thepurity of the bentonite over large areas suggest thatthe ash fell into a relatively quiet sea where no local
currents prevented its accumulation and at a time when
there was insufficient bottom agitation to mix it withother sediments.
In Scott County, Va., fragments of bentonite atleast 0.15 foot thick were found in 1953 by Leonard
D. Harris of the U.S. Geological Survey in an interval
selected by Hass as a likely one in which to look for an
extension of the Center Hill bentonite bed (oral communications, Hass and Harris). The Virginia bentonite
bed is identical in appearance to the Center Hill bed in
Tennessee, and in all probability it is part of the sameash fall.
The only other known reference to possible Late
Devonian volcanic activity in the southeastern UnitedStates is by Price and Woodward (1940, p. 1992). They
reported one or more thin sheets of igneous rock in the
Naples shale of Clarke (1885) in southern Pendleton
County, W. Va., and tentatively explained them as surface flows of Late Devonian age. It seems unlikelythat the source of the ash in the Chattanooga shale wasin or near Pendleton County, though no precise cor-

32

CHATTANOOGA SHALE, RELATED ROCKS,CENTRAL TENNESSEE AND NEARBY AREAS
86°OQ'

86° 30'rj
M A r n N /TENNESSEE", ___ . __'_ __ KENTUCKYROBERTSONy'- .Springfield/ S U. M N E R

JM

A

*->

»J

IN

* /

""TROUSDALET I

J->A^*>
Painesl

7

SMITH.Winchester,'\ / H A M I L T 0 N -'\IFRANKLIN
LINCOLNTENNESSEE _ __ALABAMA ,

M A R

I 0 N

)'

/' )

~T

f
Chattanooga\

1__ TENNESSEE ^_; GEORGIA r

EXPLANATION
Bentonite locality showing thickness
in hundreths of a footKnown and probable bentonite
Nearby Chattanooga shale locality
where bentonite is absent

Inferred bentonite

Well where bentonite was observedin cuttings

7. Map showing distribution of the Center Hill bentonite bed.

relation of the strata in the two regions has been made.
In West Virginia a bentonite of early Middle
Devonian age has been widely noted in drill cuttings
and was reported (Flowers, 1952) to be almost identical with the Upper Devonian [Center Hill] bentonite
in Tennessee. Flowers mentioned a probable slighteastward thickening of the bed but believed the source
was not in West Virginia. Fettke (1952) stated thatthe same bed is present throughout much of Pennsylvania and south-central New York. Although the bentonite in West Virginia and States farther north issomewhat older than the Tennessee bentonite, all thisunusual bentonite may have originated in the same area.
The only suggestion as to the source of the ash is that it
may be related to the volcanic activity that is recordedin rocks of Early Devonian and Mississippian (?) age
in New Hampshire (Billings, 1955). If the prevailingwind direction in Devonian time was from the west, astoday, the preservation of single ash falls in these areas,
instead of the several that might be expected, probably
resulted from fortuitous winds that carried the dustof a single explosion hundreds of miles in a southwesterly direction.
Correlation of individual ~beds. Any attempt to explain the alternation of the black and gray beds of theupper unit of the Dowelltown must take account of a
distinctive succession of beds beneath the bentonite. In
all places where especial note was made of the underlying beds, they were found to consist, in downward
succession, of about 0.1 foot of dark-gray shale, a few

CHATTANOOGA SHALE

33

tenths of a foot of light-gray claystone, and about 0.5 bentonite bed that appears to be a continuation of thefoot of dark-gray shale. The constant presence of the Center Hill bentonite bed (p. 31).
The upper unit of the Dowelltown member in mostdark-gray shale just below the bentonite over an area ofseveral thousand square miles shows that conditions of its central area is about 10 feet thick (table 3, col. B,
favoring black mud accumulation existed widely at the Iocs. 74 to 107). Near the middle of this area, however,time of the ash fall. The consistent succession of beds at and near locality 99 (fig. 8) the Center Hill benjust below the bentonite suggests further that at a given tonite bed and, presumably, the overlying beds of thetime the conditions suitable for one or the other type of member are absent (fig. 8). For several miles to thedeposition existed over wide areas, but that environ- north and south, the beds above the bentonite show aments permitting black mud and gray mud deposition generally progressive thinning toward this locality
did not exist randomly and simultaneously in nearby (table 3, col. #, Iocs. 65 to 107). From these relationareas. Had they so co-existed, the bentonite would lie ships it is deduced that some condition at the end ofon black shale at some places and on gray claystone at Dowelltown time, perhaps a slight uplift of the sea
bottom, caused marine planation to remove the upper
others.
Attempts to correlate other black and gray beds of part of the unit. Furthermore, it seems likely that at
the upper unit of the Dowelltown member over large locality 99 an additional V/2 feet of the member isareas were unsuccessful. The fact that most of the missing, for at that place only 7^ feet of the upper
individual beds can be correlated satisfactorily only unit is present, in contrast to about 9 feet that is
between nearby outcrops probably indicates that, dur- present below the bentonite at nearby localities 98 anding the long period of time when they were accumulat- 102. Evidence is lacking as to whether the bentonite
ing, minor uplifts, local currents, or other conditions is present in outliers of the shale immediately to theresulted locally in decreased deposition or actual re- west and northwest, so the distribution of the bentonite
moval of some of the mud, so that many submarine in that area is unknown.
South of the area of its maximum thickness, thediastems, most of them unrecognized, are present within the unit. At some outcrops a slight channelling or upper unit of the Dowelltown member thins rapidly intruncation can be seen in the beds, but many more southern Coffee County and disappears in the northernsuch diastems probably escaped notice, either because parts of Moore and Lincoln Counties (pis. 7, 8; fig. 8;
they were not searched for with sufficient care or be- table 3, col. #, Iocs. 107 to 114). Because the only recognizable bed of the upper member, the bentonite, iscause the outcrops are of too limited lateral extent.
Extent and thickness. Along the eastern edge of the absent in most of this area of thinning, it is not possible
Nashville Basin the gray claystone beds, which give to determine whether erosion of the upper beds is thethe upper unit of the Dowelltown member its distinc- cause of thinning, though that seems like a plausible
tive appearance and permit its recognition, extend from explanation.
Northward from the area of maximum thickness, thecentral Jackson County to northern Lincoln County, a
upper
unit of the Dowelltown member thins graduallynortheast-southwest distance of about 85 miles. FromthroughPutnam and Smith Counties and the southernwest to east the gray beds have been recognized from
partofJacksonCounty until it finally disappears as asoutheastern Williamson County to northern Ehea
recognizable
unit
in central Jackson County (fig. 8).
County, a distance of about 100 miles. It has someHowever,thebentonite
bed is at its customary positimes been thought that these beds continue as a recogtion near the top of the unit in much of this northnizable unit into southwestern Virginia, and Swartz
ern area, as it is not in the southern area of thinning(1927, p. 494) named a much thicker sequence of simi(table 3, cols. B and #,; Iocs. 35 to 65). Column F oflar beds there the Olinger shale member of the Chat- table 3 shows clearly that the beds below the bentonite
tanooga shale. However, later studies by Hass (written are the ones that are thinning. Obviously the northcommunication to Leonard Harris, July 8, 1953) on ward thinning cannot be explained by simple erosion
fossils collected by Harris, H. J. Dunham, K. L. Miller, of the top of the unit, else the bentonite would be one
and Hass indicate that the Olinger shale member of of the first beds to disappear. The cause of this conSwartz is correlative with some part of the Gassaway dition is not known, but it seems probable that themember of central Tennessee and that the upper unit lower gray beds of the central area grade northwardof the Dowelltown member of central Tennessee is into black shale of the lower unit. In other words, graycorrelative with part of an underlying sequence of bed conditions were not as widespread at the beginningblack shale in southwestern Virginia. This correlation of upper Dowelltown time as at the end. An alternativeis strengthened by the later discovery by Harris of the explanation, which seems less likely, is that one or more

34

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS
86°00'TABLE 3. Thickness data on the Dowelltown member, eastern edgeof the Nashville Basin

85° 30'EXPLANATION[Localities listed from north to south. Measurements in feet. Dashes indicate unit
is absent]
Dowelltown member

Area within which bentonite is known orthought to be present
1.2
9.3

Locality(pi. 1; table 13)

TENN
CelinaCLAY

O 107

Localities of outcrops listed in text table 3
36'
O
Numerator offraction is distance between bentonite
30'/'
and top of the Dowelltown member; denominator is ^.. distance from top of bentonite to base of upper unit
V27 /*of the Dowelltown member. Dash in numerator -=-O \, O
indicates absence of bentonite; dash in denominatorindicates entire upper unit of the Dowelltown
member is absent

10

27
00

36
35.-- _
58.. ___ . _ 64.-- __ - _ 6573. __74___ 76 . - ___ cm
98. ___ __QQ103... _ . ___ 104. ___ - ___ 107
111.. ___ _
1 19

36 C
00'

114... _____ 121

B

C

Total

Upper
unit

Lower
unit

0.8
2.0
2.4
3.5
5.8
8.1
8.0
9.4
9.2

5.3
4.0
4.2
4.1
6.5
6.1
5.2
6.5
5.6
6.7
6.2
6.8
5.9
4.8

e.i

9.2
7.4
9.0
9.4
7.5
10.5
5.1
3.7
2.5
4.0

Distance
Distance
between from top ofRatio of bentonite bentonite
upper to and top of to base oflower
member upper unit
unit
D

A

5.3
4.0
5.0
6.1
8.9
9.6
11.0
14.6
13.6
16.1
15.4
15. fl
15.0
12.2
18.5
16.2
16.4
18.4
14.0
10.0
9.1
5.1

F

E

KY

e.s

6.8
8.9
7.9
8.8
6.3
6.6
1.1

6.19
.49
.37
.57
1.1
1.2
1.4
1.4
1.5
1.3
1.5
1.5
.95
1.4
.84
1.3
.57
.59
.38
3.6

0.4
1.3
1.0
1.4
1.0
.9
.8
.5
.1

2.0
2.2
4.8
6.7
7.0
8.5
8.4
8.6
9.1

.0
1.4
.5
1.2
.2

9.0
8.0
7.0
9.3
4.8

unobserved disastems in the lower part of the gray-bed
unit cut out gradually increasing amounts of the unit
northward. Another possible explanation is that lessdeposition was taking place at that time in the northernarea, but this one too seems unlikely, for in general
the beds tend to be somewhat coarser in that direction.
GASSAWAY MEMBER
LITHOLOGIC CHARACTERISTICS

35'
30'

Winchester
FRANKLIN

MARION
Jasper35°00'. _ _ TE N N E S SJEEALABAMA

101020 MILESFIGUEE 8. Map of outcrops that show the thinning of the upper
unit of the Dowelltown member.

The upper member of the Chattanooga shale in its
typical outcrops and throughout most of the area of
this study is a massive black shale having no conspicuous subdivisions, though in many places a few
inconspicuous beds of gray claystone are present near
the middle of the member. In general, the black shalesof the Gassaway member are somewhat more massive
than are the shale beds of the Dowelltown member (pi.
10A), and along the northern edge of the Basin they
are somewhat darker. When broken the black shaleemits a distinctly petroliferous odor. In the freshest
exposures the shale commonly breaks with a conchoidal
fracture, but where weathered it is finely fissile andbreaks into thin sheets (pi. 10Z?).
Even the most massive shale in the formation contains discontinuous thin laminae of siltstone, most ofwhich are so inconspicuous that they are seen only on
freshly broken or polished faces (pi. 9Z>). Apparently
the organic matter binds the fresh rock together, butweathering opens cracks parallel to the extremely thinlaminae in the rock.

GEOLOGICAL SURVEY

PROFESSIONAL PAPER 357

PLATE 10

Ridgetop shale
Maury
formation
1-2 feet

Chattanooga
shale
19.4 feet

OrdovicianXlimestone
A. MASSIVE BLACK SHALE OF THE GASSAWAY MEMBER OF THE CHATTANOOGA SHALE SHOWN IN CONTRAST WITH THE FRIABLE SHALE OF THE
DOWELLTOWN MEMBER
A lenticular sandstone bed as much as 0.25 foot thick, at the base of the Gassaway, is correlated with the Bransford sandstone bed. The white rule across most of the
Dowelltown is 3.5 feet long and stands on the 0.8-foot basal sandstone of the Chattanooga. The Maury formation, which has phosphate nodules in the middle, grades
into the overlying Ridgetop shale. Locality 195. 1950.

B. TYPICAL OUTCROP OF WEATHERED CHATTANOOGA SHALE, IN ROAD CUT
Weathering has brought out a latent fissility and caused the rock to break into small shaly pieces. The man's left foot is at the top of the middle unit of the Gassaway
member. The position of the Maury is marked by a reentrant just below the chert beds of the Fort Payne. Locality 78. Photograph by Andrew Brown, 1948.

GEOLOGICAL SURVEY

PEOFESSIONAL PAPER 357

PLATE 11

A. PHOTOMICROGRAPH OF BLACK SHALE OF THE UPPER UNIT OF THE GASSAWAY MEMBER SHOWING REGULARITY OF THE LAMINATION
Note the paper-thin, more or less regular laminae of quartz siltstone interbedded with thin beds of more variable composition. Most of the equidimensional grains arequartz; most of the elongated light particles in the central dark band are resinous matter. Abundant organic matter caused a normal thin section like this one
to be largely opaque. From a diamond-drill core taken from locality 93. Photograph by J. M. Schopf. X 38.

B. PHOTOMICROGRAPH OF BLACK SHALE OF THE UPPER UNIT OF THE GASSAWAY MEMBER SHOWING IRREGULARITY OF THE LAMINATION
Note the bed of quartz siltstone that pinches and swells markedly within the length of a 1-inch-thick section.
X 38.

Same specimen as A above. Photograph by J. M. Schopf.

GEOLOGICAL SUEVEY

PROFESSIONAL PAPER 357

PLATE 13

B. MAURY FORMATION BETWEEN THE FORT PAYNE CHERT AND THE CHATTANOOGA SHALE
The inverted T-rule rests on top of the Chattanooga shale, and its top almost reaches the lop of the Maury, here
2.6 feet thick. Phosphate nodule layer at base of Maury is here about 6 inches thick. Massiveness of the Fort
Payne chart is well shown. Locality 82. 1950.
A. "VARVED" BED AT BASE OF MIDDLE UNIT
OF THE GASSAWAY MEMBER OF THE CHATTANOOGA SHALE

C. MAURY FORMATION
Base of inverted T-rule rests on massive Gassaway member of the Chattanooga shale. Maury is here 2.7 feet thick.
lower 1 foot. Rule is 3 feet high. Locality 76. 1950.

Phosphate nodules occupy

PROFESSIONAL PAPEK 357

GEOLOGICAL SURVEY

PLATE 16

B. PHOSPHATE NODULE BED AT BASE OF THE MAURY FORMATIONA STANDARD SECTION OF THE MAURY FORMATION
The inverted T-rule, 1.5 feet high, rests on the Chattanooga shale and touches theFort Payne chert. The hammer head spans the interval of abundant large phosphate
nodules. Locality 185. 1952.

The bed here is nearly 2 feet thick, one of the thickest exposures known. Note thevariety of shapes, sizes, and orientations of the nodules. Locality 68. Photograph
by T. M. Kehn, 1953.

C. CONTACT BETWEEN FORT PAYNE CHERT AND MAURY FORMATION
The lower half inch is Maury, the upper half inch is massive chert of the Fort Payne. The large central part is cherty limestone of the Fort
Payne that has scattered blue-green chips like the dark mass within the Maury at left. Specimen from Locality 68.

35

CHATTANOOGA SHALE

Petrographic examination shows the shale to be composed of finely laminated quartz, clay, organic matter,
pyrite, and other constituents, most of the grains being
in the size range of silt and clay. The sorting andlamination are pronounced, and many of the laminae
are only paper thin and are composed almost wholly ofquartz (pi. 11-4, B}. The discontinuity and irregularityof the siltstone laminae that are visible at most outcrops and in thin sections (figs. 31 and 33) indicate thesmall irregularities that characterized the floor of the
Chattanooga sea and the deposition thereon.
Wherever beds of the Dowelltown member are missing and the Gassaway member is at the base of theformation, the Gassaway commonly has a sandstone
at the base a fraction of an inch to a foot thick. The
sandstone normally contains the conodonts Palmatolepis gldbra, P. perlobata, Polylophodonta conjluens,and others that are restricted to the Gassaway (Hass,
1956).
Along the northwestern edge of the basin, where boththe Dowelltown and Gassaway members are present, athin bed of sandstone is present at the base of the
Gassaway member at almost every good outcrop.
Mather (1920, p. 19), Bassler (1932, p. 140), and Campbell (1946, p. 884) have previously called attention tothis sandstone. Campbell designated it the Bransford
sandstone member of his Gassaway formation, and weare referring to it as the Bransford sandstone bed. The
sandstone contains abundant conodonts, a few smallbone fragments, and parts of Oyclora-libe> gastropods
that have been derived from the Ordovician limestones.
One of the best and thickest exposures of this sandstone is in the railroad cut at Bakers Station in northern Davidson County (loc. 204) where it is about 4
inches thick. Where Campbell chose the type localityof his Bransford sandstone member, in eastern Sumner
County (loc. 206), it is generally about 0.1 foot thick.
Table 4 summarizes some of the observed thicknessesof this sandstone bed and shows the thicknesses of theoverlying and underlying shale.
TABLE 4. Thicknesses of units at selected outcrops where theBransford sandstone bed is present
Thickness (in feet)
Locality (pi. 1 liable 13)

22.
182..
195....
204...
205
206

Gassaway
memberBransford
sandstone
bed

Dowelltown
member

13
12.6
15
12.6
16.1
16.2

0.01(?).2
0-0.25
.4
0-0.2
.1

4.4
8.6
4.3
16.9
15.0
17.0

f

Farther eastward the examined outcrops do not show
the Bransford sandstone bed consistently, but at a few
553638 61-

places as far east as Jackson County 10 to 15 feet of
massive black shale is underlain by thin beds or films
of conodont-rich sandstone that may be the basal bedof the Gassaway member. The sandstone bed was notobserved in outcrops along the eastern edge of the
Nashville Basin, but several diamond-drill cores taken
during the summer of 1953 in the vicinity of Smithville and elsewhere along the Eastern Highland Rimfrom Jackson County to Coffee County show an obscurelayer of siltstone, at most a few millimeters thick, at ornear the base of the Gassaway member. This is probably an equivalent of the Bransford sandstone bed
along the northern edge of the basin.
In the northern part of Tennessee and generally in
Kentucky, the topmost beds of the Gassaway member
contain phosphate nodules that are commonly scatteredthroughout the upper few feet but locally are concentrated in one or more courses. This nodule-bearing
shale is commonly overlain by a profusion of more
tightly packed nodules at the base of the Maury formation (pi. 1GB).
At a few places, particularly in northeastern Mississippi and in the adjacent part of Tennessee, theentire Gassaway member consists of sandy shale andsandstone. These beds are commonly dark gray to
black, contain the usual large amount of comminuted
plant matter, and are somewhat glauconitic. This typeof material is especially characteristic near the Whetstone Branch (loc. 235) outcrops in northeastern Mississippi that were described by Morse (1930, p. 50-53).
Mellen (1947, p. 1811) pointed out that in this area the
shale is progressively sandier to the west, and apparently this area is near the ancient shoreline of the
Chattanooga sea.
EXTENT AND THICKNESSThe Gassaway member has much the widest distribution of any part of the formation; it was identified
either by lithologic character or by conodonts at every
outcrop of the black shale that was studied (pi. 7).
Along most of the northern and eastern edges of the
Nashville Basin it is typically 15 to 20 feet thick (pi.
12). In the southern and western parts of the Basinand the southern half of the western valley of theTennessee River, the Gassaway. is much thinner andgenerally constitutes the entire thickness of the Chattanooga shale, including those places where the formation is only a few feet or a few inches thick. To thenortheast, along the Cumberland Valley of Kentucky,
the Gassaway thickens to about 40 feet. In northern
Alabama and Georgia its thickness ranges from 0 to atleast 40 feet. The phosphate-bearing black shale at the
top of the Gassaway is as much as 8 feet thick in south-

36

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

era. Kentucky but decreases in thickness southward
until it disappears in DeKalb and White Counties,
Term. In most of Tennessee the thickness of the Gassaway member is probably roughly proportional to thelength of time the sea covered any given area.
As with the Dowelltown member (p. 29) the Gassaway member was found, in a 15-mile series of drill
cores and outcrops near Smithville, to thin westward
toward the Nashville Basin. This thinning, shown infigure 10, amounts to about 5 feet. Careful measurements also show (figs. 9, 10) that some lithologic
units tend to be thicker in the syiiclines and thinner
in the anticlines. This relation suggests that theflexures were mildly active during the time of Chattanooga deposition, so that more muds accumulated insagging areas a small-scale illustration of the conditions we think existed in the Flynn Creek cryptoexplosive area: that is, where the sea bottom wassagging, the shifting muds kept the sea bottom level.
LOWER AND UPPER CONTACTS

The contact between the Dowelltown and Gassaway
members was discussed in the section dealing with theDowelltown member (p. 29). Along the eastern edgeof the basin the exact base of the Gassaway is identified
in some places with difficulty because of the presenceof two or three thin beds of gray claystone in what isprobably the lower half foot of the member, but commonly the interval of uncertainty is not over 6 inches
thick.
Locally at the top of the Gassaway member (top of
the Chattanooga shale) there may be another obscureunconformity, though satisfactory evidence for it ishard to find. At most places the contact with the baseof the Maury formation is line sharp, but other physical evidence of an unconformity is almost wholly lacking. A quarry outcrop in Limestone County, Ala. (loc.
142), shows about 1 foot of Chattanooga shale, but elsewhere along the remaining few hundred feet of the
exposure the Maury formation rests directly on shaleof Silurian age. Near Waynesboro, in Wayne County,
Tenn. (loc. 242), a poorly exposed creek bank outcrop
shows the Maury resting with apparent unconformity
on gently folded Chattanooga shale. At the excavation
for the New Johnsonville steam plant site in Humphreys County, Tenn. (loc. 253), where the rocks arebadly disturbed, about 1 inch of conglomerate ispresent locally at the apparent base of the Maury.
These three outcrops are suggestive of local erosion
before Maury time, but the evidence is not conclusive.
Cores that were obtained during drilling in 1953
along the Eastern Highland Rim, especially near
Smithville, DeKalb County, reveal what might beconsidered additional evidence for an unconformity
at the top of the Chattanooga shale. Correlations of
the cores taken at east-west intervals of about 1 milefor distances of 12 to 14 miles (figs 9, 10) show irregularities at the top of the Gassaway member that may
indicate an erosional interval before the overlying
Maury formation was deposited. This evidence consistsof (a) differences in thicknesses of the upper unit of
the Gassaway that can best be explained by assuming
an erosion interval -at the close of the Chattanooga deposition, and (b) the presence at one place, drill hole
29 (fig. 10), of an apparent outlying mass of the phosphate-bearing shale beds that constitute the topmost
part of the formation farther north but that are generally absent in the region of the drill cores.
Hass (1956, p. 23), on the basis of his studies of theconodonts, found evidence of a time break at the topof the Chattanooga shale in much of the area of ourstudy. This evidence is the absence in large areas ofthe distinctive conodont fauna that is associated withthe uppermost part of the Chattanooga shale thatcharacteristically contains scattered phosphate nodules.
Where the phosphate-bearing black shale beds at the
top of the formation are thin or missing, a time oferosion or of nondeposition may be represented, though
little physical evidence was found to substantiate thisinterpretation.
BASIS FOR SUBDIVISION

Three persistent lithologic subdivisions of the Gassaway member were traced for about 80 miles along thewestern edge of the Nashville Basin. This three-folddivision is based entirely on the presence of a thin
middle unit, 2 to 3 feet thick, in which a few inconspicuous gray claystone beds are present within theotherwise massive black shale (fig. 5).
At places where the middle unit of the Gassaway
member is absent, no satisfactory basis was found for
subdividing the member. Where the Gassaway is morethan 7 or 8 feet thick and the middle unit is not recognizable, it is probable that the black shale represents
the interval of the middle unit as well as parts of thelower and upper units.
LOWER UNIT

The lower unit of the Gassaway member in mostplaces consists almost wholly of massive black shale
having paper-thin partings of very fine sandstone orsiltstone. Pyrite is present as films, thin lenses, andscattered nodules. This unit of the Gassaway member
is commonly about 5 to 8 feet thick on the eastern edgeof the basin where it can be differentiated from theblack shale of the upper unit of the Gassaway by thepresence of the intervening unit of claystone beds.

|(
JOWEL TOWN

Chert

|
MEMBER UPPER UNIT=~^'~"- .

i^'"j-r=Phosphatic claystone

X

<

1
<

F= «,

3AS AWAY MEMBER

MIDDLE UNITr~

MAUR Y FORMATIONBlack shale

EXPLANATION

1

sasssaSe . _ ___----""

85°55'

85°55'^=Z

III ' '

33

Claystone

85°50'

85? 50VERTICAL EXAGGERATION X 520
DATUM IS BASE OF GASSAWAY MEMBER

85*45'

85M5'

3 MILESI

85°

FIGURE 9. Cross section along an east-west line of diamond-drill holes that passes 2 miles south of Smithville, Tenn. The upper drawing shows several gentle folds superimposed on the regional dip. The lower drawing shows the relative thicknesses of the five lithologic units of the Chattanooga shale and of the Maury formation. Note that the
shale tends to be thinner up the dip and on the crests of the anticlinal folds. End of section east of the Center Hill Reservoir is based on drill-hole and outcrop data not oaline of section. From Kehn (1955).

DEVONIUPPERAN

LOWER
MISS.

LEIPERS LIMESTONEFORT PAYNE CHERT

34

CO
-4

Phosphatic black shale

Phosphatic claystone

Claystone

IT
I
II
Limestone

85°50'

85°45'

3 MILESI

See figure 9 for further explanation.

VERTICAL EXAGGERATION X 520
DATUM IS BASE OF GASSAWAY MEMBERVERTICAL EXAGGERATION X 26
DATUM IS SEA LEVELFIGURE 10. Cross section along an east-west line of diamond-drill holes that passes 3 miles south of SmithviUe, Tenn.

Black shale

Chert

EXPLANATION

85°55'

From Kehn (1955).

1100'

85°40'

CD

I

O

O

|

W

oo

39

CHATTANOOGA SHALE
NORTH

SOUTH
KENTUCKYTENNESSEEDISTANCE

BETWEEN

Center Hill bentonite bed

L-10

LOG A L I T I E S, I N

MILESClay stone

FIGURE 11. Correlation of units of the Chattanooga shale in northern Tennessee and southern Kentucky. Locality 35 is the northernmost
one where the 5 indicated subdivisions of the Chattanooga and the Center Hill bentonite bed have been positively identified.

Along the northeastern edge of the basin, where theunderlying gray claystone of the Dowelltown member
is either thin or absent and the overlying middle unitof the Gassaway is also thin, this lower unit of the
Gassaway is only about 2 to 4 feet thick. These relationships in the northeast corner of the Basin are shownin figure 11. Farther north, in Kentucky, the lower
unit thickens to about 20 feet.
MIDDLE UNIT

Along the eastern edge of the Nashville Basin the
middle unit of the Gassaway member, about 2 to 3 feetthick, contains a few gray claystone beds about 1 to 2
inches thick, which set this unit apart from the lower
a,nd upper black shale units of the Gassaway (fig. 5).
This obscure but persistent unit is easily overlooked ina casual examination of an outcrop, but its distinctive
characteristics aid greatly in correlating the shale fromplace to place. A bed of fine to very fine sandstone at
the base of this unit is commonly 1 to 4 inches thick,but its thickness is so variable that in some exposures

it pinches out laterally in a few feet from a 2-inch bed
to a mere film. The top of the middle unit is arbitrarily
placed at the top of the highest bed of gray claystone.
The sandstone bed at the base of the middle unit of
the Gassaway member shows such a marked alternationof thin carbonaceous shale and noncarbonaceous layersof very fine sandstone and siltstone as to give the appearance of a varved bed (pi. ISA). It is finely
cross laminated and ripplemarked. At most outcrops
the color of the noncarbonaceous layers is light brown,
and the bed as a whole has a rusty brown appearance
that contrasts with the blacks and grays of the otherbeds of the Chattanooga shale. In unweathered samples
the sandstone and siltstone are light gray. The base isinvariably sharp and rests on a bed of black shale. The
bed grades upward into the overlying black shale by agradual increase in thickness of the black layers, a corresponding thinning of the brown layers, and a decrease in grain size from very fine sandstone to siltstone. Though informally referred to as the "varved'*

40

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

bed, there is no evidence that seasonal fluctuations are
involved. The bed is present at nearly every outcrop
for 50 miles along the eastern edge of the NashvilleBasin from Putnam County to Coffee County. In theeasternmost outcrops in Putnam and DeKalb Counties
the bed is thinner and difficult to find, but in the morewestern outcrops of the Eastern Highland Eim it is
thicker and slightly coarser grained. At some outcrops,
especially near the northeast corner of the basin, one ormore somewhat similar beds were seen at higher positions, but most of those beds grade both upward anddownward into the black shale.
Along most of the eastern edge of the basin the
middle unit of the Gassaway member contains aboutfour or five beds of gray claystone, but farther north,in Jackson County, only three claystone beds are consistently present. Widely scattered observations indicate that the unit is also present in Clay County at thenorth edge of Tennessee and in Monroe and Cumberland Counties in southern Kentucky. Farther northeast in the area of the Wolf Creek Reservoir, a similar
unit about 2 feet thick also has three beds of the grayclaystone and is believed to be correlative with the one
in Tennessee (fig. 11); if it is, the unit is almost continuous for a north-south distance of at least 140 miles.
Along much of the northern edge of the NashvilleBasin the middle unit cannot be identified, but apersistent thin pyritic sandstone or siltstone bed is at
the approximate position of the "varved" bed. The bed
is about 2 to 3 inches thick and is 2 to 4 feet above thebase of the Gassaway member. It is easily recognizedon outcrops because the pyrite decomposes rapidly,
leaving the bed slightly recessed and in some places
covered with secondary sulf ate minerals. The equivalence of this bed with some part of the middle unit of
the Gassaway is suspected but not established.
The middle unit of the Gassaway member was notrecognized along the southern, or western, edges of thebasin, nor in the Sequatchie Valley to the southeast. Its
absence in the southern part of the basin, where theDowelltown member is also absent and where theGassaway member is relatively thin, seems to indicatethat this area was not submerged by the Chattanooga
sea until a somewhat later time. The absence of thisunit in the other areas probably signifies that the
special conditions requisite for the formation of graybeds did not extend that far.
UPPER UNIT
The upper unit of the Gassaway member consists
almost entirely of massive black shale and is similar tothe black shale of the lower unit of the Gassaway
except that it is somewhat more massive and tough.

Most fresh exposures commonly show conspicuoussmooth joint facies that extend from top to bottom of
the unit (pis. 6J., 10A) and locally continue through therest of the Gassaway member. This upper unit isprobably present wherever the black shale is exposed
and in some areas, especially southern Tennessee, isthe only unit of the Chattanooga present. Apparently
the Chattanooga sea had its greatest extent in this partof the United States in late Gassaway time.
Along the eastern edge of the basin the upper unitof the Gassaway member is commonly 6 to 7 feet thick,but along the southern edge it is locally thinner orabsent, as is the entire formation.
North from DeKalb County, Tenn., the upper unitof the Gassaway member becomes appreciably thicker,
in places as much as 13 feet. This greater thickness
results largely from the presence of a northwardthickening wedge of phosphate-bearing black shale
beds at the top. In northern Tennessee small scatteredphosphate nodules are common in the upper 1 to 3 feetof the Gassaway; still farther northeast, in the area ofthe Wolf Creek Reservoir in Kentucky, the phosphatebearing beds are 5 to 8 feet thick (pi. 7, fig. 11). These
phosphatic beds are not to be confused with a thin bedof closely packed phosphate nodules in the overlying
Maury formation.
DISTRIBUTION OF THE CHATTANOOGA SHALE

As already mentioned, the black shales of Devonianand Mississippian age in North America are notable
for their great extent (pi. 14). Within the part of thesoutheastern United States covered by this report the
Chattanooga shale is also remarkable for its thinness.
The distribution and the gradual changes in thicknessof the formation are shown on plate 15.
Ulrich (1911, p. 357) stated, without giving supporting evidence, that the Chattanooga shale "pinches out
on the very gently sloping surface of the Nashvilleisland of the time * * *," apparently referring to theregion of the Nashville dome. This statement has beenquoted and the conclusion adopted by some writers.
Available evidence, however, indicates that some partof the Chattanooga shale covered nearly all the present
Nashville dome (pis. 7, 15). The continuation of theformation across the present area of the NashvilleBasin is indicated by the presence of the shale (a) at all
examined outcrops along the northern edge of theBasin, (b) on many widely scattered outliers near thecenter of the Basin, some of which are close to thecrest of the dome, and (c) on the abundant outliers
across the southern part of the basin. On some of theoutliers no measurable outcrops of the shale were
found, but careful search of slopes consistently reveals

CHATTANOOGA SHALE

fragments of the shale, and most road cuts at the right
altitude show the shale.
One of the most interesting and significant known
outcrops is on an outlier near the southeast corner ofWilliamson County (loc. 185), within about 10 milesof the axis of the Nashville dome. Here a iTVi-footexposure of Chattanooga shale shows about 5l/2 feetof strata of the Gassaway member overlying about 12
feet of beds of the Dowelltown member. A generalthinning of the beds towards the crest of a Late
Devonian arch, as indicated by plates 7, 8, 12, and 15
and by figures 9 and 10, suggests that the arch waseither rising slightly while the sediments were accumulating or was already slightly higher than the surrounding region. However, most of the Late Devonianarch, as well as the area of the present Nashville arch,
was not an island during most of Chattanooga time.
With but few exceptions within the area of thisreport, about 40,000 square miles, the black shale ispresent wherever its position is exposed. The chief
exceptions are two areas west and southwest of the
Nashville Basin that existed as islands in the Chattanooga sea, and outlying areas in Alabama and Mississippi that may have been beyond the bounds of the
Chattanooga sea (pi. 14); at these places the shale was
not deposited or it was removed before deposition of
the Maury formation.
One of the island areas where all the Chattanooga
shale except the Hardin sandstone member is absent
includes large parts of Lewis, Wayne, Lawrence, andGiles Counties, Tenn., and extends into northern Limestone County, Ala.; it is an irregularly shaped large
area, here referred to as the Hohenwald platform. The
shale thins to zero on the flanks of this ancient platform but the Maury formation covers the entire area.
At the beginning of Gassaway time the platform may
have been part of a great land area to the south that
had not yet been submerged by the Chattanooga sea.
During much of the time of Gassaway deposition thearea must have been an island that was decreasing insize as the sea spread over more and more territory but,so far as can be determined, 1,500 squares miles still
remained unflooded at the end of Gassaway time (pi.
12).
A second place where the Chattanooga shale is absent
is in western Davidson County and eastern Cheatham
County, Tenn. As shown on plate 15, two small, nearlyadjacent islands seem to have existed during the deposition of the Chattanooga shale, but they too were later
submerged so that the Maury formation blankets themboth. Only a small amount of field data from this area
supports these statements; further work would undoubtedly result in many changes in the hypothetical

41

outline of these islands and provide a better basis forunderstanding their history. Though the manner ofoverlap is similar to that onto the Hohenwald platform,
the rate of thinning toward these islands is surprising.
For example, the Chattanooga is 28 feet thick at
locality 198 but is absent 1 mile to the north acrossthe Cumberland Elver at locality 197. Contrary towhat might be expected, however, the lithologic character of the several Chattanooga units, where present
here, is not notably different from that in other areas.
It is possible that the shale was stripped from these"island" areas before the beginning of Maury time. If
it was, diligent search might reveal one or more nearby
outcrops where the Gassaway member is absent andpart of the Dowelltown is present, a condition unknownat present in the Chattanooga shale.
Near the south and southwest limits of the region ofthis study, in Alabama and Tennessee, the Chattanooga
shale is also absent at many places. This observation,
however, is based almost entirely on information fromwidely scattered outcrops and wells, and the significance of the distribution is not understood. Along Red
Mountain in the vicinity of Birmingham, Ala., theblack Chattanooga shale is very thin or absent andpresumably was not deposited to the east and southeast.
However, about 27 miles southwest of Birmingham in
Bibb County (E^SE^ sec. 34, T. 21 S., E. 6 W.), a
U.S. Bureau of Mines core revealed about 25 feet of
Chattanooga shale. At the southwesternmost part of
Eed Mountain near Woodstock, Ala., about 5 miles
south of the drill hole, the shale is only about 5 feetthick, yet some 15 miles farther south, at Pratts Bluff,
about 5 miles northwest of Centreville, 17 feet of Chattanooga shale is present. The Pratts Bluff locality is
the southernmost place where the Chattanooga wasstudied, and its proximity to a shoreline is suggested
by abundant layers, lenses, and balls of sandstone, andby quartz sand and pebbles that are scattered throughthe layers of silty black shale. Thus, the southern limitof Chattanooga shale deposition is not actually known
because it is beneath the Coastal Plain and opportunities for getting information on distribution of the shale
are not good. In the Coastal Plain regions farther
south the likelihood of finding the shale in drill holes
is slight, even if it is present in the buried Paleozoic
rocks that are an extension of the eroded and structurally complex folded Appalachian belt.
Sparse information from wells near the AlabamaMississippi State line suggests the shale was not deposited in most of Mississippi. Outcrops and fairly
reliable data from wells in northeastern Tishomingo
County, Miss., and southern Hardin County, Tenn.,show the limit of the main body of the Chattanooga

42

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

shale in that area. In 1955 Mellen called attention to
Chattanooga shale in scattered wells in northeast Mississippi, but it is not known whether these are remnantsof black shale that once blanketed the area or whether
they represent irregular embayments into the land area.
So far as is known, the Chattanooga shale is absent
beneath most of the Coastal Plain area of western
Tennessee. This may result partly from Late Paleozoic
or Mesozoic erosion, but much of this area may havebeen a part of the Ozarkian landmass that was supplying sediment to the Chattanooga sea.
Foerste (1901, p. 428-429) cited one locality near
Rockdale, Maury County, Tenn., that suggested to him"erosion of Black shale during early deposition of the
Waverly [Maury formation of this report]." Dunbar(1919, p. 92) stated "in the Western Valley [the Chattanooga shale] is uniformly thin and locally absent atmany places, apparently due to later erosion." Swartz(1924, p. 29) apparently believed that the thinning andabsence of the Chattanooga shale beneath the "invariably present" Maury formation in western Tennessee are the result of partial or complete erosion of the
Chattanooga shale and hence are evidence for a marked
unconformity. As already indicated, however, in mostplaces the absence of the shale is the result of nondeposition rather than of pre-Maury erosion.
Morse (1930, p. 54) described an unconformity "ofgreat magnitude" in Tishomingo County, Miss., separating his Whetstone Branch shale (Chattanooga
shale) from his Carmack limestone (partial equivalentof the Ridgetop shale and Fort Payne chert, having theMaury formation as a basal unit). He based his conclusion on two lines of reasoning: He described a conspicuous "basal conglomerate" of the Carmack limestone, which is, in reality, a bed of large phosphate
nodules embedded in glauconitic sandstone typicalof the Maury formation in northeastern Mississippi
and nearby areas in Tennessee and Alabama; he also
described the Carmack as lying, in different areas, onseveral different formations including his Whetstone
Branch shale. This overlap by the Maury apparently
results not from erosion of the black shale, as suggested
by Morse, but from lack of deposition of the shale.
According to Jewell (1931, p. 37-42), an unconformity separates the Chattanooga shale from the overlying
Eidgetop shale in Hardin County, Tenn. To understand his reasons for this interpretation, the following
stratigraphic units and their relationships must bepresented, as used by Jewell: A "Maury glauconitic
member" is assigned to the Chattanooga shale, thismember being recognized at only four localities in the
county; the next younger unit is the Kidgetop shale
which, with the exception of the four localities, hedescribed as overlying the black shale or the Hardinsandstone (also a member of the Chattanooga shale).
Apparently the supposed absence of the Maury isJewell's reason for placing an unconformity between
his Chattanooga (our Maury formation) and the
Ridgetop, although he stated (p. 39) that the absenceof the black shale of the Chattanooga is also indicativeof the erosion interval. The confusion of stratigraphic
units and the resulting interpretation of erosion can be
resolved merely by pointing out that Jewell placed theMaury formation of this report with the Chattanooga
shale at four localities and in the lower part of the
Ridgetop at all other localities. The latter assignmentis understandable because the true identity of theMaury is masked by its gradation into the overlying
Ridgetop. At every outcrop we studied during thisinvestigation, in Hardin County and elsewhere, theMaury was present at its normal position.
Campbell (1946, p. 896-900) described erosion intervals near the close of Chattanooga time and shortly
thereafter. He assumed a complex regressing andtransgressing shoreline to explain the presence andabsence of one or more very thin beds separating themain part of the Chattanooga shale from the formation
overlying the Maury. Whether or not such thin units
are everywhere present or are in part absent, the fact
remains that such a delicate pattern of subaerial erosion
as called for by Campbell is unlikely. The lithologic
variations within the Maury can be more plausibly
explained by assuming local or regional submarine
hiatuses or by merely assuming that different lithologic
facies are present.
COMPOSITION OP THE CHATTANOOGA SHALE

Quantitative determination of the mineral composition of the shale is extremely difficult because of thefine grain size of the rock and the masking effect of theabundant organic matter. Chemical analyses of several
samples of the shale have shown the amount of pyrite
and organic matter in the rock and have served tocheck the estimates made from study of thin sections.
As each chemical analysis is of a sample that represents a thickness of about 2 feet, it is somewhat moreindicative of the bulk composition of the shale than isa thin section, which represents an inch or less of the
shale. Rough estimates of the mineral composition
were made from several thin sections, and one of thechemical analyses was recalculated in a manner consistent with known facts about the shale. Detailed
studies at Pennsylvania State College under the direction of Dr. T. F. Bates of the mineralogy of a core of
the Chattanooga shale from near Smithsville, Tenn.,showed that the chief clay mineral is illite, or hydro-

CHATTANOOGA SHALE

mica, which constitutes somewhat less than 10 percentof the black shale samples but 15 percent or more of thegray claystone beds (Strahl and others, 1954, p. 38-39).

43

TABLE 6. Chemical composition of shales and graywackes
4, Composite analysis of 51 Paleozoic shales; adapted from Clarke (1024, p. 552).
B, Average graywacke; adapted from Pettijohn, (1949, p. 271). C, Chattanooga
shale, same as sample C in table 5. Z>, Same as C, after recalculating for ignition
loss]

CHEMICAL DETERMINATIONSAChemical analyses of samples of typical massive
black shale of the upper unit of the Gassaway memberof the Chattanooga shale in Tennessee are shown intable 5. The shale of sample 0 is believed to be theleast weathered and therefore should have provided thebest analysis.
TABLE 5. Chemical analyses of outcrop samples of Chattanooga
shale in Tennessee[A, from loc. 60; Gassaway member, probably the uppermost 2 feet; collected by
K. G. Brill and others. B, from loc. 64; Gassaway member, probably 4 or 5 feet ofthe upper part; collected by A. L. Slaughter and others. C, from loc. 92; a 2-footsample taken 3.7-5.7 feet below base of the Maury formation. Analyses are byBattelle Memorial Institute, Columbus, Ohio. Used by permission of U.8. Atomic
Energy Commission]
SampleSiOj.
TK>!
... ...
Ah03
FejOa
- ...
MgO......
... ... . ..... ....
CaO.
NajO. .
KjO........ ....... . . .
PjOs
COj8...
C
H.. .....
Total. ___ . _ . _ . _

....
....
.
.
.
....
.....

A

B

C

23.4
46.00

24.9
48.60

U1.60
10.70
.95
1.46
«
3.79
.96
.20
6.80
14.50
1.60

110.40
9.90
.78
.21
(2)
3.40
.27
.10
5.90
14.60
1.00

23.0
49.30
.69
10.71
9.60
1.22
.36
.33
4.03
.12
.31
«6.90
14.30
1.55

98.56

95.16

99.42

i Includes TiOj, ZrOj, VjOs.
a Included with K2O.
a Separate analyses give: 0.8 percent organic sulfur; 0.3 percent sulfate sulfur; 5.7
percent pyrite sulfur (=10.7 percent FeSs).

In table 6 the average analyses of shales and graywackes are compared with sample G of table 5. The
analysis of sample G includes the large amount of substances lost on ignition, so column D of table 6 was
prepared to facilitate comparisons. Although theaverage analyses of the shales and graywackes include
some constituents that are lost by ignition, those substances are sufficiently small in the graywackes that
their presence does not appreciably affect the relative
quantities of the other important constituents for purposes of rough comparisons.
Comparison of column D with columns A and B
shows that, except for the high iron content, the blackshale has a chemical composition much like that of aquartz-rich detrital sedimentary rock. The abnormallysmall quantities of MgO and CaO in the black shale
doubtless result from the acidic conditions on thesea bottom, which hindered precipitation of those
substances.
The investigations of the mineralogy of the shalethat were made at Pennsylvania State University

SiO2.~TiOz.
AlaOs
FeaO3
.... ... ... ...
FeO
MgO. ._CaO ...........
...
NajO.
.

B

C

HjO. ............................
P2O5...... ....................
COj........ .......... ........
Misc
_

60.15
.76
16.45
4.04
2.90
2.32
1.41
1.01
3.60
4.71
.15
1.46
1.50

64.0
.5
14.0
1.3
4.1
2.9
3.4
3.5
2.1

Total......................

100.46

KtO. ............................

D

49.30
.69
10.71
9.60

64.55
.94
14.00
12.57

1.22
.36
.33
4.03

1.60
.47
.43
5.28

1.5
.1

.12
.31
22.75

.16

99.6

99.42

100.009 1.1(Bates, 1953; Bates and others, 1953; Strahl and others,
1955) included chemical analyses and studies with lightand electron microscopes and with electron and X-ray
diffraction and other equipment. These studies showedthat the denser and darker parts of the shale, whichcontain the most uranium, have the approximate composition shown in table 7.
TABLE 7. Mineralogic composition of the more uraniferous partsof the black shale[Analysis by Pennsylvania State University]

Weight(percent)

Quartz ___________________________ 20-25
Feldspar ________________________ 10
Clay and mica ______________________ 25-30
Pyrite ___________________________ 10-15
Organic ____________________________ 15-20
Other ____________________________ 5

Another study at Pennsylvania State University(Kinney and others, 1957, p. 14) of the organic matterin the black shale of the Chattanooga led to the conclusion that the organic content of the rock ranges from
19.6 to 20.5 percent.
PETBOGBAPHIC DETERMINATIONS

The following generalities are drawn from study ofthin sections of rocks in the Chattanooga shale: (a)The chief detrital mineral grains of the massive blackshale are silt-size quartz and somewhat smaller amountsof clay and mica, and these grains are well sorted; (b)the gray claystone is finer grained than the black shale,contains larger amounts of clay and smaller amounts ofquartz, and is poorly sorted; (c) amber-colored ellipsoidal spore cases and other plant matter, much of whichis shredded, are disseminated throughout the blackshale and are concentrated locally in some of the layers;(d) the quartz-rich parts of the formation contain mostof the organic matter.

44

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

An obvious characteristic of the black shale beds of
the Chattanooga shale, especially the more massive bedsin the Gassaway member, is the extremely fine grain
size of most of its constituents. Grains of practicallyall the minerals range from silt-size particles downward to the limit of visibility with a light microscope.
Under these conditions it is obviously difficult to determine the identity of many of the grains, more so to
calculate their proportions. The studies at Pennsylvania State University (Bates, 1953; Strahl and others,
1954, p. 31) showed that some of the grains that appear
to be quartz are feldspar. Minute mica flakes large
enough to be recognized by the naked eye are scatteredthroughout the shale, especially in those parts that are
best stratified. Miscroscopic masses of phosphate arepresent in much of the shale, even in those parts that
do not show nodules on the outcrop. Calcite, thoughconstituting only a small fraction of 1 percent, is observed in thin sections as widely scattered single crystals or minute lenses. Zircon is present as sparsely
scattered tiny grains. In volume the light-weightorganic matter, present as films and masses, is roughly
estimated to constitute about a third of the rock; thisvolume is consistent with the 15 to 20 percent organic
matter by weight that has been found by other studies.
One of the most strikng microscopic characteristicsof the seemingly nearly massive black shale is a wellmarked lamination that results from a high degree ofsorting of the grains (pi. 11). Many paper-thinlaminae are composed almost solely of quartz and have
sharp upper and lower boundaries. Adjoining laminae
have various mixtures of other constituents.
In general the most massive and densest shale of the
Chattanooga, chiefly in the Gassaway member, is extremely fine-grained argillaceous quartz siltstone, richin organic matter and pyrite. The fissility of this blackshale when weathered is clearly the result of the highdegree of sorting and lamination. By contrast, theshale of the lower unit of the Dowelltown member,which is somewhat less massive in the outcrop, is lesswell sorted and has fewer of the paper-thin laminae ofquartz.
The gray beds of the upper unit of the Dowelltown
member are finer grained than the black shale and contain more clay. Thin-section study indicates that clay,
or some other equally fine-grained mineral, constitutes
about 65 percent of the rock; recognizable quartz, pyrite, and organic matter about 10 percent each; andmica, calcite, and zircon much smaller amounts. The
organic matter is more abundant in the layers that contain the most quartz and is relatively sparse in the clayrich beds. In contrast with the black shale beds, thegray beds have mineral grains of less parallelism andthe lamination is poor. These clay-rich beds, which arepoorly laminated and nonfissile, may appropriately becalled claystone.
The black beds between the gray beds of the upper
unit of the Dowelltown contain quartz whose averagegrain size appears to be somewhat greater than that of
the quartz in the gray beds. The grains in the black
beds are much better sorted than those in the gray beds
but are not as well sorted as those in the more massive
black shale of the Gassaway member.
The sandstone in the Hardin sandstone member, as
seen in thin sections of two typical samples from Olivehill and Waynesboro, Tenn. (Iocs. 238 and 243), is composed dominantly of fine-grained quartz. Most of thequartz grains range in average diameter from 0.02 to
0.1 mm, though at Olivehill some are appreciably
larger. Feldspar grains, recognizable by albite andmicrocline twinning, are scattered throughout but
probably constitute less than 1 percent of the rock.
Glauconite and phosphate are likewise sparsely scattered through the sections. Calcite makes up a quarterto a third of the Waynesboro sample and is apparently
a secondary cement. Pyrite grains are scatteredthroughout but constitute hardly more than 1 percent.
A few small fragments of fossils are also present. The
quartz grains are poorly rounded, and many of them
have acute-angled corners. In general, the larger grains
seem to be somewhat more angular. The thin sections
show the same uniformity of grain size and lack of
bedding that characterize the outcrops.
The sandstone at the base of the Chattanooga-Maury
sequence, which ranges in age from earliest Dowelltown to Maury, varies greatly in composition and grain
size from place to place. The sandstone generally contains quartz, chert, phosphatic remains of assorted
fossils, pyrite, and calcite, all in widely varying proportions and sizes. The fossils consist of shell fragmentsfrom the underlying formations, many of them phosphatized, of angular and rounded fragments of bone,and of fragmentary conodonts. Calcite is commonly
secondary and encloses other ingredients. Feldspar
grains showing microcline twinning are common but
make up less than 1 percent of the rock. Widely scattered grains of glauconite are present in some samples.
Zircon is sparsely present as small scattered grains.
Where no Chattanooga shale is present and theMaury formation rests on the pre-Chattanooga rocks,
the basal sandstone is commonly rich in glauconite andphosphate. The phosphate consists both of transported(allogenic) fragments reworked from the underlying
land surface and of masses that enclose detrital grainsof the sandstone and have obviously formed in place(authigenic).

CHATTANOOGA SHALE

Thin beds of sandstone are common in the Dowelltown member and locally are present in the Gassaway
member. Most of these beds are a small fraction of aninch thick, but locally they are thicker; in a few places
they make up a significant part of the member or theformation. Most of the sandstone beds in the shale arecomposed chiefly of poorly rounded quartz and varying
amounts of chert, pyrite, and calcite. Widely scattered grains of glauconite are commonly present. Phosphate is also present as rounded fragments of bone andundetermined objects and as irregular masses. Feldspar
grains that can be recognized by albite and microline
twinning make up less than 1 percent of the rock.
Zircon and other heavy minerals are sparsely scattered.
The Bransford sandstone bed at the base of the
Gassaway member along the northwestern edge of the
Nashville Basin is composed chiefly of fine to medium
quartz sand but contains many fossils, notably conodonts, bone fragments, teeth, and phosphatized parts of
Cyclora-\i]s& gastropods.
The "varved" bed at the base of the middle unit of
the Gassaway member consists chiefly of quartz, together with mica, clay, spores, and other organic
matter. The concentration of the organic matter inlayers gives the rock its banded or varved appearance.
Zircon grains, though small, are fairly abundant. Mostof the quartz grains are between 0.008 and 0.07 mm indiameter, much the greater part of them being in thesize range of silt (less than 0.062 mm).
In Hardin and Wayne Counties, Tenn., and in nearby parts of Perry County, Tenn., and Tishomingo
County, Miss., the Chattanooga shale is chiefly a calcareous and phosphatic quartz sandstone having thinlayers of black shale. Morse (1930) recognized theequivalence of these beds with the Chattanooga shale
but proposed the term Whetstone Branch formation
for them (p. 18). A thin section of typical calcareous
sandstone from Morse's type locality along Whetstone
Branch (loc. 235) shows poorly sorted and poorly
rounded quartz sand having abundant fragments ofphosphatic fossils of many types. Pyrite is irregularly
distributed, chiefly as interstitial fillings. Feldspar,showing albite and microcline twinning, makes up 1 to
2 percent of the thin section.
More details concerning the size, shape, and othercharacteristics of the constituents of the shale are givenin the following paragraphs, in which the individual
minerals are discussed separately.
QUARTZ

Extremely fine grained quartz is the major constituent of the black shale beds of the Chattanooga and45

probably makes up about 20 to 25 percent of the rock.
Partings of quartz silt are visible throughout theformation, and petrographic examination shows eventhinner partings to be especially characteristic of what
appears on the outcrop to be the most massive part of
the formation (pi. 1L4). Within the densest blackshale are microscopic layers, commonly less than 0.1
mm thick, composed of quartz grains ranging from 0.02
to 0.06 mm and averaging about 0.03 mm in greatest
diameter. Still finer quartz ranging in diameter fromabout 0.004 to 0.012 mm and averaging 0.008 mm isdisseminated fairly uniformly throughout the massive
shale. For ease of comparison, it may be pointed outthat the coarser grains mentioned ( those averaging
0.03 mm in diameter) are about one-third as thick as asheet of common letter paper, and the grains 0.008 mm
in size are about one-third as thick as the tissue sheets
commonly used for carbon copies of letters. It may betruly said that the laminae in the shale are paper thin!
The investigations of the mineralogy of the Chattanooga shale at Pennsylvania State University (Bates
and Strahl, 1957, p. 1307) revealed quartz that is far
below the range of ordinary microscopic visibility. In
the course of that work, small amounts of quartz were
found in the 0.4-micron fraction but not in the 0.3micron fraction.
In general, the quartz grains are typical sand grainsthat show various degrees of roundness but few othercharacteristics indicative of their history. No solution
pits were observed that would suggest slow solution in
the soil on the old land surface, and no crystal outlines
were noted that would suggest the grains originatedas tiny euhedral crystals in the nearby limestones.
Secondary growth was seen on a few grains of a sandstone layer from the shale in Lawrence County, where
the formation is only 2 feet thick (loc. 151), but otherwise no post-depositional alteration of the quartz
grains was observed. Seemingly, most of the quartz
grains in the shale have experienced repeated cycles ofnormal sedimentation and are lacking in such indicative features as excessive angularity, marked roundness, solution cavities, or secondary growth. Regardless of their history, of course, the fine silt and clay
grains would not show these features.
At a few places we saw quartz veins as much as 2
and 3 inches wide in the Chattanooga shale. Becauseof talus, they were seen no place where their downward extent could be determined, but they were observed to pinch out at or near the top of the shale.
The quartz crystals are elongated perpendicular to thewalls and appear to have grown toward the center ofan open crack, filling the space only imperfectly.

46

CHATTANOOGA SHALE, BELATED BOCKS, CENTRAL TENNESSEE AND NEARBY AREASMICA

FEIJ>SPAR

Freshly broken surfaces of the shale commonly show
reflections from minute micaceous grains that may be
muscovite, sericite, or hydromica. Study of several
thin sections indicates that the mica content isabout 5 to 10 percent. The range in grain size is relatively small, nearly all the mica flakes having greatest
diameters between about 0.01 and 0.06 mm and mostof them between 0.025 and 0.035 mm. The flakes arealigned almost perfectly with the stratification andare well distributed throughout the rock.
Abundant black mica resembling biotite was observed in fresh samples of the thin Center Hill bentonite bed that is in the upper part of the Dowelltown
member of the Chattanooga shale. When exposed toweathering, the black mica in the bentonite becomesalmost colorless and resembles muscovite or sericite inappearance. Workers at Pennsylvania State University (Strahl and others, 1954, p. 8-9) believed thatthe biotite alters to kaolinite. Except in this thin bed
of bentonite, biotite was not seen in the Chattanooga
shale, but Geological Survey laboratory mineralogicaland chemical studies (Deul, 1957, p. 215) of samplesof the massive black shale of the upper part of the
Gassaway member have shown that biotite is present
in quantities estimated at 1 percent.

The sandstone layers of the shale commonly contain sparsely scattered grains of feldspar that arereadily recognized by their albite or microcline twinning. The grains are about the size of the associatedquartz grains and are clearly of detrital origin. In
none of the thin sections we studied does the easily
identifiable feldspar make up as much as 1 percent of
the rock. Feldspar is not readily recognizable in thethin siltstone laminae or other parts of the massive
black shale.
The Pennsylvania State University studies (Bates
and Strahl, 1957, p. 1307, 1312) show the presence oforthoclase, plagioclase, and sanidine feldspars in themassive black shale that constitutes the upper unit of
the Gassaway member. Feldspar makes up about 9
percent of the rock. Orthoclase is the most abundant feldspar and "* * * commonly shows distinct
crystal outlines suggesting authigenic origin." Manyof the other feldspar grains also have authigenic
overgrowths.

CLAY

The studies at Pennsylvania State University of themineralogy of a core of the Chattanooga shale (Bates
and Strahl, 1957, p. 1308), showed that the chief clay
mineral is illite but that some kaolinite is alsopresent. Chemical studies of 60 samples chosen
at random from the core indicated that the clay content of the "blackest" unit of the shale is only about 7
percent and that the highest clay content of any of
the recognized lithologic units of the formation is
only about 16 percent. Only one sample contains morethan 20 percent clay. These findings (Strahl andothers, 1954, p. 38-39) are summarized in table 8.
TABLE 8. Clay content of Chattanooga shale[Adapted from Strahl and others, 1954]
Stratigraphic unit

Gassaway member:
Middle unit-. __ . ... __ ..

Dowelltown member:
Chattanooga shale (entire formation).

Thickness(feet)

Number Clay content (percent)ofsamples
Kange
Mean

6.5
2.6
8.7

12
4
15

4. 40-9. 37
8. 94-15. 50
6. 98-14. 85

7.08
12.11
9.71

11.0
7.2
36.0

15
14
60

10.15-21.40
4. 15-19. 14
4. 15-21. 40

15.87
11.56
11.44

PYBITB AND MARCASITE

Laboratory investigations of the Chattanooga shale
have shown that both pyrite and marcasite are present.
The marcasite, however, constitutes only about 2 percent of the sulfide in the shale (Bates and Strahl, 1957,
p. 1308). Iron sulfide generally is referred to as pyritein this report.
Pyrite is common in the black shale and ranges insize from submicroscopic cubes less than 0.15 micron
on a side (Bates, 1953) to crystalline spherulites andlenses as much as an inch thick. Most of it is present
as microscopic lumps of irregular shape and as
spherules as small as 0.02 mm in diameter, but larger
nodules of fine-grained pyrite, about 4 to 6 mm indiameter, are liberally scattered through the shale.
Many spores are filled and surrounded by pyrite.
The pyrite visible to the naked eye is commonly concentrated in layers ranging in thickness from thin anddiscontinuous films to nodular masses as much as aninch thick, around which the shale has been warped.
Some of the pyrite visible to the unaided eye shows
distinct crystal faces.
The minute spherules of pyrite probably formed
during or shortly after black mud deposition, but thelarger masses may have resulted from short-distancemigration of the sulfurous compounds while the muds
were still unconsolidated. Many siltstone and sandstone beds within the shale are markedly pyritic andlocally these beds have cavities encrusted with pyrite
crystals.

47

CHATTANOOGA SHALE

Along the northern edge of the Nashville Basin apyrite-rich siltstone bed in the lower 2 to 4 feet of
the Gassaway member seems to be a traceable lithologic unit. The bed is commonly about 2 to 3 inches
thick, contains roughly 50 percent pyrite, andweathers to a soft and friable material coated withyellow and white sulfate blooms. This bed can betraced at least 50 miles from western Davidson County
to central Macon County. Because it seems to indicate a unique set of chemical and physical conditionsin the Chattanooga sea, which is not recognized elsewhere in the section, this bed is believed to be a time
marker.
The pyrite in the shale breaks down readily upon
exposure and forms several secondary minerals. In
some places the pyrite yields a distinct "bloom" ofyellow and white crystals that were identified by
Charles Milton (Milton and others, 1955) of the Geological Survey as copiapite (a yellow hydrous ferricsulfate), coquimbite (a white granular hydrous ferricsulfate), and halotrichite (a finely fibrous whitehydrous ferrous aluminum sulfate). Minute gypsum
crystals are seen commonly on joint faces or bedding
planes along which water has been able to seep.
PHOSPHATE

Phosphate is present in the Chattanooga shale bothas detrital grains (allogenic) and as a chemical precipitate (authigenic). The detrital grains represent
two types of sources: One type is made up of reworked
fragments of bones, shells, and undetermined objects
from the older rocks; the other type consists of phosphatic bones, shells, conodonts, or other parts oforganisms that lived in the Chattanooga sea or drifted
into it.
The most notable example of the detrital type is the"blue phosphate" in Perry, Hickman, Lewis, andMaury Counties where residual matter from the
Leipers limestone of Ordovician age has been reworked into an unusual type of sandstone at the baseof the Chattanooga. Smith and Whitlatch (1940,
p. 302) reported that the "blue phosphate" is composed chiefly of the mineral cellophane, together withvarious amounts of fibrous dahllite, pyrite, quartz,
chalcedony, and shaly material. In the southwest
part of the area that was studied for this report,
especially in Wayne and Hardin Counties, Tenn., andin Tishomingo County, Miss., much of the lower partof the Chattanooga shale is an impure phosphatic
black sandstone. Studies of thin sections show thatreworked small phosphatic particles are also scattered throughout the formation and are especiallyabundant in the sandstone beds.

The chemical precipitates of phosphate are nodules
or plates that are common in the upper few feet of
the Chattanooga shale, chiefly in the northern partof the area studied. They are by no means as abundant as in the immediately overlying Maury formation
but are scattered through one or more beds. The
nodules are subspherical or discoidal in shape, commonly about 1 to 3 inches thick. The plates are
typically somewhat less than an inch thick but are
as much as several feet long. Most of the nodules
and plates are parallel to the bedding of the shale,
but some cut across the beds at different angles. Someof the nodules appear to have pushed the beds aside,
but in part they also cut out the beds. When broken
open a large number of the nodules are found to haveat or near the center an organic object, such as ashell, conodont, or bone fragment (for example, Maher
and Dunkle, 1955).
Whether the nodules in the black shale formed on
the surface of deposition and were buried later, took
shape in the sediment very soon after deposition, oreven formed after the shale had been compacted is, inmany instances, uncertain. Such criteria as termination of the laminae against the nodule or bending of
the laminae around the nodule can be used to ascribe
syngenetic, diagenetic, and epigenitic origins to thesenodules.
PI^ANT MATTERAs already pointed out (p. 19), thin layers of coaly
material are seen occasionally in the shale and havebeen mistaken for bitumen. Breger and Schopf(1955) stated that the material is vitrain corresponding in rank to high-volatile A bituminous coal. Theygave the analyses of a bed of this material that ishalf an inch or more thick (table 9).
TABLE 9. Analyses of vitrain from the Chattanooga shale[Analyses by U.S. Bureau of Mines, lab. rept. E-32291, Feb. 2,1954. Sample fromloc. 203B, Davidson County, Tenn.]
Moisture
free

Moist ureand ashfree

40 6
55.1
2.2

41.4

An A

56.3
2.3

57.6

5.6
77.1
1.7
9.8
3.6
2.2
14,340

5.5
78.7
1.7
8.2
3.6
2.3
14,640

5.6
80.5
1.7
8.5
3.7

As received
Proximate analysis:
AshUltimate analysis:

Ash...
Btu-

2.1

14,990The half-inch of coal at locality 203B, which appears to contain parts of several stems, is unusuallyrich in uranium (0.033 percent) and germanium

48

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS(0.051 to 0.057 percent) and other metals. As it
seems unlikely that the plant matter acquired so muchgermanium from the sea water, Breger and Schopf
suggested that the plants acquired the germanium
before they were floated into the sea, then absorbed
the uranium from the sea water. It is probable thatthe shale contains no true bitumen but that all asphaltic or bitumenlike material in the shale is coalified
plant matter or, more rarely, the carbonized remainsof fossil fish.
OTHER CONSTITUENTS

At many outcrops hydrochloric acid was appliedsystematically to all beds to test for calcite. A slightobservable reaction on a few thin beds indicates thata small amount of calcite is present at some localities,
but most of the shale shows no reaction on the freshly
broken surface, and the chemical analyses of the blackshale indicate that calcite is uncommon. In thin sections of the black shale only a few scattered grainsof calcite were seen, and in thin sections of the grayclaystone a few discontinuous tiny lenses of calicte
or dolomite were seen. Calcite is fairly common at
many places in the lower 2 or 3 feet of the shale andin many of the sandstone beds of the formation.
Secondary calcite forms a coating on some of the joint
surfaces.
In the southwestern part of the area the impure andphosphatic shale is somewhat calcareous, especially inthe lower sandy units.
In central Kentucky the lower 10 to 15 feet of the
Chattanooga shale contains several layers of calcareous siltstone as much as 6 inches thick. Farther south,in Sumner and Trousdale Counties, Tenn., is thesomewhat calcareous basal shale (p. 18) that Pohl
thought should be considered a separate formation.
In general, throughout the area of these studies, calcareous impurities are fairly common in the lower
part of the shale but are uncommon in the higher part.
Chert grains are common in the sandstone at thebase of the Chattanooga shale. The grains doubtlesswere weathered from the older limestones and later
concentrated into the relatively coarse detritus at thebase of the Chattanooga shale. Secondary chert iscommon in all the sandstone beds that were studied
in thin section and is presumed to have formed soonafter the detrital grains accumulated.
Chalcedony was reported (Smith and Whitlatch,
1940, p. 302) as a cementing ingredient in the "bluephosphate."
Chlorite was detected by X-ray study at Pennsylvania State University (Weaver and others, 1952, p. 5;
Bates and others, 1953, p. 31), though it has not been
observed otherwise. It constitutes a part of thatgroup of miscellaneous minerals that make up lessthan 5 percent of the shale.
Glauconite is a minor constituent in all the sandstone beds that have been studied but is absent orrare in the shale and its associated siltstone laminae.
Tourmaline and zircon were reported by investigators at Pennsylvania State University (Weaver
and others, 1952, p. 19) to be fairly common accessory minerals. The tourmaline grains are about 0.03
to 0.05 mm in length and the zircon about 0.01 to 0.02
mm in length. A few of these grains can be seen inalmost any thin section of the formation, but nowhere
are they known to be at all concentrated. They makeup only a small fraction of 1 percent of the rock.
Single galena crystals 1 to 2 mm in diameter wereobserved at two outcrops of the black shale (Iocs. 54,
84). Their origin in the shale is unknown, but it
seems likely that they were formed in the muds, as
was the pyrite.
PALEOGEOGRAPHY DURING LATE DEVONIAN" TIMEThe Late Devonian sea spread far beyond thebounds of the area studied for this report (pi. 14),
and any full discussion of the origin of the sediments
necessarily includes the wider area. Northern Alabama, Tennessee, and southern Kentucky seem to havebeen close to the southeastern limit of the sea, andthe sources of the sediments appear to be fairly definitely known. Figures 12 and 13 are interpretationsof land and sea areas during Late Devonian time.
From the land-sea relations shown in those figuresand from knowledge of the thicknesses of shale andother sediments deposited in the different parts, some
general deductions can be made concerning the various sources and the relative quantities that they
contributed.
REGIONAL TECTONIC INFLUENCE

Central Tennessee is fully 400 miles southwest of
the center of thickest sediment accumulation in eastern West Virginia, where at least 10,000 feet of sedimentary rocks of Middle and Late Devonian age are
known. From this area of maximum thickness, theserocks thin at a fairly constant rate along any 300mile line of radius that trends between north-northwest and south-southwest. Beyond this 300-mileradius is a vast region extending westward to theMississippi River where Upper Devonian rocks, predominantly black shale, average about 100 feet inthickness. Thus during Late Devonian time thegreater part of the eastern United States consisted
largely of three major tectonic elements: a geosyncline, its complementary landmass to the east, and an

CHATTANOOGA SHALE

49

ASy-

ffi

A
£.
«
aft
,»

in
f
y

J

V

o
^
cu
O

j.*'
*

O
o-l

Q)
IX
Q-

/r^

"^)

h

V

lip

n

4 s

r

oj

B

(a
0
^

c

60

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

ILLINOIS BASIN<(
K
E
N
rrgL.400 FEET)

T

«TSO
SOUTH
"^CAROLINA

EXPLANATION
Lowland shoreline marking approximately the maximum
extent of sea on interior platform
Shoreline, interpreted from published reports
Lines of equal thickness, in feet, generally defining minor
elements on interior platform
Lines of equal thickness, in feet, on strata in geosynclinalarea; rocks, for greater part, still remaining-IOOO-

Lines of equal thickness, in feet, on estimated cumulative
thickness of strata in geosynclinal area. Much of thisarea probably uplifted during Late Devonian, and sediments, then only recently deposited, were eroded andredeposited to the west
fGeosynclinal axis drawn on line of maximum thickness

FIGCEB 13. Map outlining paleotectonlc and paleogeographlc features In the eastern United States near the end of the Devonian,based on generalized thickness and distribution of the rocks.

CHATTANOOGA SHALE

interior platform. Each of these elements is shownon figure 13.
GEOSYNCLINE

A detailed description of the location, magnitude,
and history of the geosyncline is not presented here,
but it should be pointed out that this is one of thetypical exogeosynclines described by Kay (1951, p.
17-20) and is not to be confused with the older concept of the "Appalachian geosyncline." Rather, thisDevonian geosyncline in the eastern United States is
a distinct historical unit, specifically identified as toits geographic location, orientation, and method of
infilling. The magnitude of downwarping of thegeosyncline is significant when considered in relation to the stable platform. In an east-west crosssection of an area of almost continuous deposition, ahorizontal time line 400 miles long could be shownto have been lowered 100 feet or less on the platform,
10,000 feet or more in the geosyncline.
This vast spoon-shaped mass of sediments deposited in the geosynclinal area might be generally
described in terms of the sedimentary rocks at its
eastern and western extremities thousands of feetof coarse sandstone and redbeds of continental origin
at its eastern edge, only a few hundred feet of marine
shales, chiefly carbonaceous, at its western edge. The
maze of interfingering types of sedimentary rocks,
and all the possible sedimentary mixtures of both
extremes, has been only partly deciphered, but it
indicates downwarp, a continuously shifting shoreline, and a continuously changing depositional environment (fig. 12).
LANDMASS

The area, altitude, and mobility of the landmass
to the east of the geosyncline, important as its rolewas, can only be inferred from indirect evidence
the sedimentary record of the geosyncline and thesparse information on scattered metamorphosed rocks
in its northern component.
The geographic location of that part of the landmass considered to have been the major source of
sediments during Middle and Late Devonian time
can be described only generally. It was an elongatedmountainous area that occupied much of the area ofthe present Coastal Plain, extending from central
Connecticut southwest to the north-central part ofNorth Carolina. One of the difficulties in any attempt to visualize the location and magnitude of thesource area is the fact that an unknown volume of
sediment was deposited east of the postulated Late
Devonian landmass. The altitude, relief, and surface rocks of the landmass at any one moment during51

its history can only be inferred from the kind,coarseness, and apparent rapidity of deposition of
the sediments laid down beyond its western margin.
An important northern component of this landmass
undoubtedly existed in the northern New EnglandStates and adjacent parts of Canada, but its geologicalsignificance relative to the rest of the eastern UnitedStates is not clear. The deformation and plutonic
activity that took place in this area and presumablysome distance to the southwest during Middle andLate Devonian time (King, 1951, p. 100) are referredto the Acadian orogeny (Shickshockian orogeny ofsome authors). Upper Devonian rocks in New England and the Maritime Provinces are seemingly eastof the Late Devonian source area.
INTERIOR PLATFORM:
The geosyncline and the landmass were tectonically
active, but the third major element was the stableinterior platform a part of which is the area of thisreport. The stability of this platform is indicated by
its earlier Paleozoic history and, more significantly,
by the extensive continuity in thickness and lithologyof the Upper Devonian deposits. However, several
minor flexures of varying significance were superimposed upon it (fig. 13) : (a) the oval-shaped Michigan basin, which had subsided to receive a great
thickness of Silurian sediments, continued to subside,
though much less, in Devonian time; (b) a small partof the Illinois basin, which subsided slightly during
the latter half of the Devonian; (c) the Ozark area,
an important positive area in mucn of Paleozoic timethat apparently existed only as a broad flat areaslightly above sea level during Late Devonian time; and,(d) marginal land areas on the southern and northernparts of the interior platform that also were broad flat
areas only slightly above sea level. Thus the interior
platform during Late Devonian time can be generally described as a stable area, with the exceptions
noted above and except for a very slow widespreadlowering of the platform about 100 feet relative to
sea level.
The general relationships between and within thetectonic elements can be only broadly described, andthe influence of these elements on sedimentation during the last half of the Devonian in the eastern UnitedStates can be only grossly defined. What knowledge
does exist, however, can be utilized to advantage in 'interpreting the sedimentary history of the Chattanooga shale.
EXTENT OF THE CHATTANOOGA SEA

The Chattanooga sea of this report is that Late
Devonian epicontinental sea in which the Chattanooga

52

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

shale and many similar correlative sediments were
deposited in the eastern and central United States.
The stages of expansion and the greatest magnitude ofthis sea (pi. 14) were interpreted from the known andinferred distribution of individual marine units of Late
Devonian age.
Much of the interior platform had been drained ofthe early Middle Devonian epicontinental sea, and aninterval of erosion beveled the uplifted and slightly
warped rocks of a broad area. In late Middle Devonian
time, marine waters again began to encroach on theinterior platform, advancing from the geosynclinalarea to the east, from the Ouachita area to the southwest,
and perhaps from the northwest across the Dakotas andIowa. Early in Late Devonian time a shallow sea
covered much of the interior platform, then continued
to transgress slowly, with one apparent slight interruption, until it reached its greatest extent near theend of the Devonian period.
The invasion of the Chattanooga sea might be likened
to the spreading of water across an ordinary concrete
floor, where slightly lower areas mark the routes ofadvance. Thus a panorama of Tennessee, Alabama,and nearby areas early in Late Devonian time would
have shown a fingering and interconnecting shallow sea
spread among broad flat lowlands ranging in area froma few square miles to thousands of square miles. Probably only a third of the entire area of this report wasinundated at this early stage.
From early in Late Devonian until the end of theperiod the sea advanced with extreme slowness acrossthe broad lowlands. The subaerial erosion of the peneplained surface had reached a stage where further
reduction of that surface was negligible, and the erosive
power of wave, current, and tidal action was at aminimum, by reason of the extreme shallowness of thesea in the irregularly shaped and sized pans. Thoughconsidered unlikely, the margins or even large partsof the lowlands may have been intermittently awash,
but any sediments that may have been laid down on
these lowlands were deposited there only temporarily
and were later removed and redeposited in the sea.
Evidence like that in the sequence of outcrops near
Bodenham, in western Giles County, Tenn. (p. 14),suggests, however, that the strandline belt of erosive
activity was narrow.
The greatest extent of the Chattanooga sea, near theend of the Devonian, can be inferred from the maximum known distribution of Devonian black shales.
Later the sea spread markedly at the beginning ofMississippian time, covered the Devonian muds on theinterior platform, submerged the islandlike lowlands,

and spread onto additional lowlands not covered by
the Chattanooga sea.
These interpretations are in accord with the evidence presented in this report and the known facts
concerning Late Devonian and Early Mississippian
stratigraphy beyond the limits of this study. The
history of deposition of the Chattanooga and related
black shales as here described differs from the concept of Grabau (1906, p. 593), which holds that theentire thickness of the black shale in a specific area
represents a short-lived shoreline phase of a transgressing Late Devonian and Mississippian sea. It
also differs from the theory of Kich (1951b, p. 2038;
1953, p. 1535-1536) that a sea covered much of theeastern United States continuously during much of
Silurian and presumably all of Devonian time butthat the black shale accumulated only after the water
became relatively deep.
SEDIMENTATIONSOURCESThe sources of the detrital sediment for the Chattanooga shale in the region of this report can be conveniently divided into four major areas, based on
their inferred location and general relief during Late
Devonian time: the large landmass to the northeast;
the lowlands bordering the Chattanooga sea to thesoutheast, south, and southwest; the Ozark area to thewest and northwest; and the island areas in the sea.
Other places at greater distances may have suppliedmuch windblown dust. Obviously, the position of any
specific outcrop of Chattanooga shale relative to thefour listed areas would alter the following generalizations on the significance of each source, but the continuity of the lithology and thickness of the formationsuggest that only slight modifications are necessary.
The eastern landmass supplied most of the sediments in the geosyncline. A stratigraphic section of
Middle and Upper Devonian rocks from eastern West
Virginia to north-central Tennessee (shown in partin pi. 12), shows that deposits are thinner and finer
grained at greater distances from the center of thegeosynclinal area. Of the great volume of sediment
derived from that landmass, an extremely small fraction may have reached the central Tennessee area, andthat must have been the finest and most buoyant, tobe transported for hundreds of miles through several
environments. Thus, some of the clay- and silt-sized
quartz and mica in the Chattanooga shale may haveoriginated far to the northeast.
Deep erosion of the folded southern Appalachians
east and southeast of the area of this study has

CHATTANOOGA SHALE

53

destroyed most of the Upper Devonian rocks, and little and silty bedrock that was exposed in the westernis known about the Chattanooga shale in that area. part of the island (pi. 3) probably contributed to the
So far as it can be traced, the shale does not thicken elastics in the nearby part of the Chattanooga shale.
What proportion of the mineral grains in the foreastward or southeastward into a coarser clastic facies;
this fact is consistent with the belief that the Late mation may be windblown is unknown, but it seems
Devonian and Early Mississippian were times of tec- likely that windblown dust, including volcanic ash,
tonic quiescence in the southern Appalachians (King, would account for a significant fraction (Koss, 1955).
1950, fig. 9, p. 661-662). It is thus assumed that a The ash that formed the Center Hill bentonite bed
land area of low relief existed in western North Caro- is an example of sediment transported by wind fromlina and that its significance as a source of sediment a distant area.
Remains of several types of marine plants are imwas intermediate between that of the landmass to theportant
constituents of the black shale, and some land
north and the lowland areas to the south.
Farther south, in northern Alabama and in nearby plants are known. The marine plants were floatingparts of Mississippi and Georgia, the Chattanooga forms that lived on or near the surface of the water.
The basal sandstone of the Chattanooga shale, inshale was deposited widely during Gassaway time. In
general this shale is fine grained, and in places seems contrast with most of the formation, is made up
to thin to extinction. These facts suggest that the largely or wholly of slightly reworked debris frombordering land was low and simply an extension of nearby sources. Quite clearly the soil on the penethe peneplain on which the shale was deposited. This plain, which was underlain chiefly by limestone, wasextensive lowland, underlain chiefly by limestone, sup- worked over by the advancing sea sufficiently that theplied some of the organic material in the Chattanooga clay and other fine material were removed. The
shale and much of the clastic sediment. A sandy facies coarser particles, including chert and quartz grainsof the Chattanooga just south of the area of pi. 1, at and fragments of assorted fossils, were moved only
Pratts Bluff 5 miles northeast of Centreville, Bibb short distances. The "blue phosphate" of West TenCounty, Ala., and in the northeast corner of Mississippi nessee has already been mentioned as an unusual form
and nearby parts of Tennessee, suggests the proximity of the basal sandstone made up largely of reworkedof large streams entering the Chattanooga sea. Glover fragments weathered from the underlying Leipers(1959, p. 156-157) has noted that the formation is limestone which, in that region, abounds in phoscoarser and more irregular in thickness toward the phatized fossils.
The thin but widespread and coarse Bransford
southeast, and that it pinches out near Birmingham,sandstone
bed at the base of the Gassaway member is
Ala.
thickestinthe vicinity of Nashville. Its source is
The eastward extent of the Ozarkian land area during Chattanooga time is postulated on fragmentary unknown, but it probably was derived from someevidence, for any Chattanooga shale that existed in nearby area that was elevated at the end of Dowellthe present Coastal Plain area of western Tennessee town time. Some of the grains may have been reand Kentucky either has been eroded or was not worked from the Dowelltown member, but a large part
reached by the drill. Freeman (1951) showed that of them, including fragments of Cyc2ora-lik& gastroOzarkia was a land area preceding Chattanooga shale pods, must have come from the older formations. As
deposition, and the area is not known to have been this sandstone bed commonly lies above several feetinundated again until middle Mississippian time. A of shale of Dowelltown age many miles from any place
progressive overlap of Upper Devonian black shale where the Dowelltown is known to be absent, theand Lower Mississippian rocks onto the Ozarkian area grains must have been transported considerable disin eastern and southeastern Missouri is known, and the tances.
The sources of other sandstone beds that are scatsame condition probably existed in western Tennessee.
A few islands apparently remained above water tered erratically through the shale, especially in thethrough all or part of Chattanooga time, and they lower part at any given place, are not known. It is
doubtless supplied some sediment to nearby parts of presumed that many of the erratic beds resulted fromthe sea. The Hohenwald platform, the largest of the abnormally strong inflow of nearby sand-carrying
known islands, was probably isolated from the main- streams. Others may be simply a local concentration
land during Gassaway time and gradually decreased of the coarser grains of the muds that had alreadyin size, but by the end of Gassaway time it was prob- been deposited and had then been stirred up by
ably still about 1,500 square miles in area. The shaly unusually strong storms or currents.

54

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS
TRANSPORTATIONThe sediment that made up the Chattanooga shale
probably was carried to their destinations by slow seabottom traction, by water suspension, and by wind.
The 200-foot thickness of finely laminated blackshale in the Flynn Creek structure is believed to showthat the sediment was shifted freely, though very
slowly, along the sea floor, which was always wellgraded. This process, oft repeated during a long spanof time, may have moved some of the sediment long
distances, especially if only small amounts of newmaterial were being brought to the region.
Transportation in suspension by water currents wasprobably an important process where fine-grained sediment was involved. By this method mud from the
nearby peneplain was dispersed widely, but it is likelythat some of the fine-grained mica and clay werebrought long distances from other areas; some sediment may have been transported westward and southwestward from the geosynclinal area in the VirginiaWest Virginia region where it was accumulating much
more rapidly; such sediment was probably the finest
grained and most buoyant of the great volume thatwas sifted and sorted by the waters in the geosyncline.
Wind may have transported much silt great distances to the Chattanooga sea. The possibilities ofthis method of transportation are strikingly illustrated by the Center Hill bentonite bed, which has
flakes of biotite about 1 mm in diameter, together withsmaller particles of quartz and feldspar. Modern dust
storms carry silt-size particles of quartz and otherminerals hundreds and thousands of miles, and asingle storm may deposit a noticeable film of dust far
from its source. If the Chattanooga shale represents
the sediment deposited through millions of years, it
is expectable that windblown dust would constitute anappreciable part of the shale. Foerste (1901, p. 431)
suggested such a method of accumulation more than
50 years ago:
The fissile black shale is composed of particles so light thatthey could have easily been blown by the wind. The remarkably
fine grained character of the fissile shales, the entire absence ofcoarser material except at their base, and their remarkably
wide geographical distribution suggest that they may possibly
consist of windblown particles, derived perhaps from many
strata, from points far distant from one another.
RATE OF ACCUMULATIONThe rate of accumulation of the Chattanooga shale
appears to have been so slow as to require consideration. The conodonts within the shale suggest that it
was accumulating throughout most of Late Devonian
time. Estimates (Marble, 1950, p. 18) of the durations of the geologic periods, based on radioactive age

determinations, indicate that the Devonian period
lasted about 55 million years; it seems probable that
Late Devonian time lasted at least 10 million years.
It may be very conservatively estimated that the Chattanooga sea covered the land during only half of thattime, or 5 million years. If 35 feet of shale, the approximate maximum normal thickness in most of thearea here under consideration, represents the accumulation of 5 million years, then each foot of shale represents, on the average, about 150,000 years. These figures, of course, have little quantitative value except toindicate an extremely slow rate of deposition.
According to Pettijohn (1949, p. 472) the probablerate of deposition for compacted shale is about 1 footin 700 years. Bradley, (1929, p. 99) in studying theGreen Kiver formation, estimated that the moderatelyrich oil shale accumulated at the rate of 1 foot in 4,700
years and the richest oil shale at the rate of 1 foot in
8,200 years.
Several studies of the fine red clay in the deep partsof the ocean basins (Shepard, 1948, p. 305-309; Sverdrup and others, 1942, p. 1038-1040) suggest that that
sediment, which is thought to have the slowest rate ofaccumulation of any modern sediment, is collecting at
the rate of about 1 foot in 60,000 years. If we assume
that transformation of this clay to an indurated rockcomparable to the Chattanooga shale would involvea loss of volume of 60 percent, we have apparently
similar rates of sedimentation for both rocks, namely
1 foot in 150,000 years. The deep-sea clay, however,differs from the Chattanooga shale in so many waysthat perhaps no comparison between them is warranted, except, possibly, the inference that the Chattanooga sea received and retained hardly more sediment than today reaches the ocean depths.
If the nearby land areas were sea-level peneplains,
as is believed, and if a geosynclinal trough lay between
the central Tennessee area and the main land mass tothe east, then it is reasonable to suppose that the Chattanooga sea received an abnormally small amount of
sediment. It may be, too, there was not a continuous
rain of particles to the sea floor; rather the sediment
may have been brought in only on relatively rareoccasions. The times when sediment was introduced
may have been chiefly when the sea was somewhat moreagitated than normal and could transport material insuspension or when an occasional dust storm supplieda small amount of silt. Another factor may have been
insufficient subsidence of the area to make room for agreater accumulation of mud. In the one known place
where more mud did accumulate, the Flynn Creek
cryptoexplosive area, there is evidence of an abnormal
amount of subsidence.

55

CHATTANOOGA SHALE

Some support for the theory that the sea bottom may
have received no sediment during extended periods oftime is the presence of scattered small phosphategrains, which have been noted in thin sections of the
shale, and of larger phosphate nodules in the upper
part of the shale. Goldman (1922) summarized evidence and opinions that phosphate nodules form on
the sea floor so slowly that their presence indicatesthat no clastic sediment was deposited for a considerable period of time.
The possibility that the laminae in the Chattanooga
shale are varves (annual pairs of layers) has been
seriously considered. Bradley (1929) and Rubey(1930) described apparent varves in the finely laminated Eocene and Upper Cretaceous shales of Wyoming and nearby areas. Both writers called attention to the alternation of laminae that are dominantlyof mineral matter with those of organic matter; theymentioned the persistence of these layers as evidenceof their accumulation in quiet water, presumably
below wave base. Both men used the varves as abasis for calculating the rate of accumulation of those
beds and obtained results that are in general agreement with estimates of the duration of those intervalsof time based on radioactivity. The average thickness of the varves of both areas is about 0.2 mm.
We concluded that the laminae in the Chattanooga
shale are not varves. In the first place, the mineralrich layers are so variable and discontinuous (pis. 9Z>,
115) as to suggest that the sediment was disturbed
and rearranged many times after it reached the sea
bottom and that conditions for the preservation offine annual layers did not exist in the Chattanoogasea. Furthermore there is no indication of a consistent gradation from one type of lamina to theother, as is usual in the case of varved sediment. Morelikely the laminae are those that were accidentallypreserved at irregular intervals on a sea whose bottom sediment was subjected to occasional agitation.
The silt layers may also represent, in part, infrequent
times when a measurable amount of silt reached thesea, either by an incursion of muddy water or by anoccasional dust storm.
In the second place, the thickness of the laminae arealtogether incompatible with a reasonable estimate of
the time required for the sediment to accumulate. As
can be seen from plate 11, the average thickness ofa pair of layers that might reasonably be considereda varve is about 1 mm. At that rate, 1 foot of Chattanooga shale would represent only about 300 years,
and the entire 15 feet of the Gassaway member would
represent about 4,500 years. More likely, however,the Gassaway member required several hundred times

as long as this to accumulate. Any estimate of theduration of Chattanooga time from calculations basedon supposed varves is so far out of harmony with theevidence, largely paleontologic, that the Chattanooga
represents most of Late Devonian time, that we donot believe the layers are varves. We conclude thatthe laminae are largely accidental and do not represent uniform periods of time.
COMPACTION

The Flynn Creek cryptoexplosive area affords anunusual opportunity to determine the amount ofcompaction the shale has undergone since the end of
Chattanooga time. As already stated (p. 10), theshale in this basin is as much as 200 feet thick, and theoverlying Maury formation and Fort Payne chert sag
about 100 feet over the thickest part (fig. 3). As also
pointed out, it is highly probable that this subsiding
area was continuously filled with the accumulating
mud. The shale within this small basin differs in noapparent respect from that of the surrounding area
except in being as much as 10 times as thick. Virtually all the extra thickness is in the Dowelltown
member.
The subsidence of the floor seems to have takenplace during Dowelltown time, and probably no further significant settling occurred during Gassaway
time. Most of the early compaction of the Dowelltown
beds also took place during Dowelltown time, and theweight of the overlying Gassaway sediment, now about
15 feet thick, was insufficient to cause much additional
compaction. Later burial, however, by probably 2,000
feet or more of beds of Mississippian and Pennsylvanian age, compressed the 300 feet of Chattanooga
shale only about an additional 100 feet to its present
thickness of about 200 feet (disregarding the compaction of the present 20 feet of shale in nearby areas,
which is assumed to have been comparable and relatively negligible).
A detailed study of the shale and the associatedrocks in this small and unusual structural and depositional basin might provide much interesting information on sedimentation and compaction in this typeof shale. The evidence cited seems to indicate that
the Chattanooga shale was reduced in thickness by
about one-third as the result of post-Chattanooga
loading.
RELATION OF BLACK SHALE TO GRAY CLAYSTONE

The reason for the alternation of black and graybeds in the Chattanooga shale is not known and noteasy to conjecture. In the upper unit of the Dowelltown member the gray claystone is the dominant rock56

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

type, but in the middle unit of the Gassaway member
it is a minor constituent (fig. 5). In both units theindividual gray beds seem to extend over large areas.
The change in conditions from one favoring the formation of black shale to one favoring gray claystone
was probably not periodic, because some black bedsin these units are hardly more than paper-thick andothers are as much as half a foot thick. The graybeds have a simlar range in thickness.
Any explanation of the alternation of the two typesof beds must take account of the following characteristics of the gray claystone: (a) It appears to represent either oxidizing conditions or less intense reducing conditions than characterize the rest of the formation; (b) the grain size of the claystone is somewhat smaller and clay minerals are more abundant
than in the black shale; (c) it is poorly laminated, in
contrast with the black shale; (d) it contains fewer
fossils than does the black shale; (e) its contacts withthe beds of black shale are commonly slightly gradational, though some are fairly abrupt; (f) in the
Dowelltown member it disappears northward from thevicinity of Cannon County, where it is thickest, bychange in facies; (g) conditions favorable for its
formation were apparently widespread over several
hundred square miles at any given time.
Although the conditions that caused the change
from black mud deposition to gray are not known, it
is conceivable that a colder climate may havecaused increased vertical circulation of the water,or periods of increased rainfall may, from time totime, have increased the flow of sediment to the sea.
Numerous other suggestions could be offered to explain
the alternations of black and gray beds, but all would
be mere speculations grounded on little or no evidence.
ENVIRONMENT OF DEPOSITIONGENERAL, CONSIDERATIONS

Just as geologists have long differed over the ageof the black shale, so they have differed in their ideason the environment in which the Chattanooga andother black shales have accumulated. Some workers
have thought that the shales originated in stagnant
basins hundreds or even thousands of feet deep, whileothers have maintained that the shales originated inshallow water or even on vast mud flats. Some havethought the shales accumulated as widespread sheets
laid down simultaneously over wide areas, while others
have thought they represented the near-shore facies
of an advancing sea. Many types of evidence havebeen used in support of these opposing views, but, asin the controversy over the age, it has been difficult

for any school to find evidence sufficiently convincing
to silence the opposition.
The Chattanooga shale is clearly a marine deposit,,
as indicated by the presence of glauconite and phosphate and of linguloid brachiopods, abundant conodonts, and a few other marine fossils. Most writers
agree that such mud accumulates in quiet or tranquilwater that is low in oxygen. In such an environment
sulfur it liberated by decomposing organic matter andpoisons the water with hydrogen sulfide, some ofwhich unites with available iron to form pyrite or marcasite in the bottom muds; the usual bottom scavengers
are absent and only anaerobic bacteria can live.
Organic matter that sinks from above or drifts infrom other areas makes the water sulfurous and generally foul. The acidic water inhibits the precipitation of carbonates and dissolves any calcareous shellsthat enter it. Mud and other sediment normally
accumulate slowly in this environment and imprison
large quantities of undecomposed plant remains andsuch phosphatic objects as bones, teeth, conodont parts,and shells of linguloid brachiopods. On this muchthere is agreement.
For comparison, some writers have pointed to the
known present-day accumulation of black mud in thedepths of the Black Sea, while others have pointed toblack muds that are accumulating in shallow parts of.
the Norwegian fjords, Baltic Sea, Chesapeake Bay,and other bodies of water. Some have argued thatthe great extent and widespread uniformity of the
Chattanooga and related black shales, together withthe general absence of ripple marks, cross-bedding,
mud cracks, and scour channels, indicate their deposition in deep seas. Others have called attention toplaces where the shale is intimately associated withcrossbedded and ripple-marked sandstones that areclearly of shallow-water origin. Some have thoughtthat the paper-thin laminations of the shale indicate
quiet and deep water, but others have thought thelaminations indicate repeated agitation in shallow
water. Some have thought that the sulfurous bottom
water requires a body of relatively deep and quiet
water to permit a density stratification, whereby stagnant bottom waters are rarely aerated by admixtureof water from the upper layers; others have suggested that stagnant and sulfurous water can and does
exist in shallow areas where abundant algal growthor absence of tides, currents, and waves leaves thewater undisturbed. Writers have been concerned, inpart, with different formations, which may have beenlaid down under somewhat different conditions, butmany have expressed conflicting opinions regarding

57

CHATTANOOGA SHALE

the same rocks and have even used the same evidence
to support opposite views.
In most of the published discussions regarding depthof water, little or no attempt has been made to define
the terms "deep" and "shallow." Unfortunately, these
relative terms have quite different meanings to different people, for example, to oceanographers and to
harbor engineers. For a long time oceanographers
commonly considered 100 fathoms (600 feet) to be
the approximate division line between shallow anddeep, and it seems probable that most geologists havebeen in general agreement with that usage. The
depth of 100 fathoms was apparently chosen becausethat was long thought to be the approximate lower
limit to which water is agitated by the largest surface
waves and because it was also thought to be theapproximate depth at the outer limit of the continental
shelves. However, submarine photographs show clear
evidence of currents strong enough to move sand at
depths of a few thousand feet. On the other hand,
Dietz and Menard (1951) presented evidence that theorthodox concept of a 100-fathom wave base is faulty
and that little significant wave abrasion takes place
below the "depth of vigorous abrasion" (p. 2011),
which they find is commonly at 5 fathoms or less.
Other factors that may be fully as important as
depth in the control of type of sedimentation include
salinity, pH value, oxygen content, temperature, density stratification, currents, wave agitation, turbidity,
and organic content, as well as the types of sediments
brought to the area by rivers, currents, winds, andfloating objects.
A primary requirement for the accumulation ofthese plant-rich muds appears to be stagnation, which
results when horizontal or vertical circulation is insufficient to take oxygenated water to the bottom.
Stagnant conditions have been reported to exist at
various depths ranging from several thousand feetin the Black Sea to a few tens of feet in some of theNorwegian fjords (Strom, 1948) and even only a few
feet in the Baltic Sea (Twenhofel, 1915), Barnegat
Bay, New Jersey (Lucke, 1935), and Chesapeake Bay(Goldman, 1924). The depths required for stagnation in a sea as widespread as the Chattanooga sea
are unknown because no comparable sea exists today.
Obviously it is difficult to select criteria that indicate satisfactorily the environment in which the widespread Chattanooga shale originated. It was necessary, therefore, to consider the significance of many
characteristics of the formation, to explore new linesof reasoning, to consider the implications of various
assumed origins, and to draw independent conclusions.
That procedure was followed in the present investiga-

tion by several workers, some of whom were only
slightly acquainted at the time with the abundantwritings on the black shale, and all came to the sameconclusion that the Chattanooga shale of the central
Tennessee area accumulated in relatively shallow waterat depths of tens of feet rather than hundreds. It
seems appropriate, however, before elaborating onthat conclusion, to cite some of the views that havebeen expressed concerning the environment of deposition of the mud.
PREVIOUS VIEWS

The belief that black shales originated in relatively
deep water was expressed by Lap worth (1889, p. 60),
Clarke (1885, p. 14; 1904, p. 199-201), Schuchert(1910, p. 446; 1915), Marr (1925), Euedemann (1934,
p. 51) and Eich (1948; 1951a, p. 13).
Studies by Androssow (1897) of the hydrology of
the Black Sea, where black mud is accumulating inwater that is mostly 4,800 to 7,200 feet deep, haveapparently led many geologists to believe that mostblack shales originated in similar isolated deep basins.
The assumption of such an isolated deep basin affords
an easy means of explaining a density stratification of
the water, the lower part of which would be unaerated
and would quickly become sulfurous from accumulating organic matter.
Clarke (1904, p. 200) thought the Devonian blackshales of New York State represent deposits in an"inclosed marine body * * * of great depth and imperfect vertical circulation."
Schuchert (1910, p. 446) thought that the blackshales represent deposits in closed or stagnant armsof the sea as in the Black Sea.
Euedemann (1934, p. 43-52) summarized many of
the opinions on the conditions of black shale deposition, and concluded (p. 51) :It can be stated as a general proposition that Lapworth's
theory of the origin of graptolite shales as a special facies
representing deposits in a quiet zone of deeper water is still
the theory best supported by the facts, and it may be added
that, for reasons given above, the same is true of most finegrained black shales.
* * * This does not mean the abyssal depths but only the
deeper littoral zones.

Eich (1948) stated that the Chattanooga and related black shales of eastern North America probably
accumulated "in relatively deep water at least below
wave base" and suggested that the black shales were
deposited "in poorly aerated water in what was thenthe deepest part of the Appalachian geosyncline."
Later (1951b) he elaborated on this idea and cited theChattanooga and related black shales of eastern
United States as examples of sediments that had ac-

58

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

cumulated in deep water his fondo environment. He
calculated that the sea was between 300 and 700 feetdeep.
Other writers, however, have thought that blackshales do not require deep water but that special conditions in shallow water would suffice. Ulrich (1911,
p. 358) suggested that the black graptolite shales of
the Paleozoic were deposited in troughs connecting
large bodies of open water or in broad shallow basins
and that enclosed areas or stagnant conditions are notnecessary. He thought (p. 357) that the black shalesof the eastern United States were formed in shallow
water because the deposits are widely distributed, thefauna is chiefly pelagic marine and requires currents
for its wide distribution, and the beds overlap to extinction on the flanks of certain areas of uplift.
Twenhofel (1915) described a place in the Baltic
Sea where black mud is accumulating in water so shallow that small boats are propelled by poles.
Grabau and O'Connell (1917) concluded that thegraptolitic shales of southern Sweden were depositedin comparatively shallow water and that similar shales
in southern Scotland were deposited in lagoons andon the flood plain of a large delta. They also cited
the Bay of Danzig on the south coast of the Baltic Sea
where the Vistula Eiver, after draining the comparatively flat country of Poland and southeast Prussia,
deposits a dense black mud having a large quantityof organic matter.
Goldman (1924) described black muds that are accumulating in Chesapeake Bay in deep holes, in deeper
parts of the tributary river bottoms, and near the
shore between the sandy shore deposits and the morescoured central channels.
Moore (1929, p. 465) suggested that the thin but
persistent beds of black fissile shale in rocks of Pennsylvanian age indicate deposition in

structure, and the like are records of the repeated changes inshallow water conditions of deposition.

extremely shallow water, with sunlight promoting plant growth
and aiding in partial decay, and with too little depth for circulation and effective wave or tidal agitation.

Later Moore (1949, p. 32) stated concerning theblack platy shales, which are high in carbonaceous andradioactive content and are unfossiliferous except forsuch noncalcareous types as conodonts, ostracodes, andphosphatic-shelled brachiopods, that they "* * * cannot be interpreted reasonably as a record of the euxinic
conditions of an unoxygenated sea bottom." Instead,he thought that "* * * such shale may be a depositof very shallow marine waters so clogged by abundant
growth of sea weeds that agitation of the bottom bywaves and currents was virtually nil."
The foregoing citations are samples of the opinions
that have been expressed concerning the origin of
black shales, and of the reasoning used in the argu-

He expressed the belief that the widespread Pennsylvanian seas of the midcontinent were probably not
more than 200 feet deep.
Morse (1930, p. 60) in describing an impure faciesof the Chattanooga shale, for which he proposed theterm "Whetsone Branch shale," (p. 18 and 42) wrote:
In some of the intervals both shales and sandstones are concretionary, crossbedded, and contorted, and some of the sandstones are ripple-marked. At one or more vertical positions
contacts of two intervals resemble contemporaneous erosion or
unconformable surfaces. All these differences in texture,

Hard (1931), in describing the black shale of theGenesee group of Late Devonian age in New York,
noted that it "is so closely related to shallow water
sediments that it, too, must have been deposited inrelatively shallow water. He also stated (p. 177):
Most of the theories about bituminous shale environment
require tranquil water to account for the "paper thin" beddingof the shales. This desired tranquillity is generally explainedby supposing that deposition occurred in either very deep orvery shallow water or in partly protected basins. However,when the fact is disregarded that the beds may have been compressed to one-fifth or less of their original thickness, it is quitepossible that any moderate agitation would not be permanently
reflected in shales, for the colloidal character and fineness ofthe material would cause it to remain in suspension during
periods of disturbance until the water again became tranquil.
When this material was redeposited, of course, some differential
settling occurred. This explains the repetition of thin layers offine quartz grains in these shales. If scour channels are retained they are extremely difficult to observe, for it is almost
impossible to trace individual lamination for any distance.

Twenhofel (1932, p. 10), in referring to previous
theories on black shales, stated that he did
not consider the deep water environment, first advanced by
Lapworth and subsequently supported by Clarke, Marr, Ruedemann, and others, as tenable in the least degree. Too many
Black Seas are required and, furthermore, the muds of theBlack Sea would not be particularly black after drying as they
owe their blackness to black monosulphide and disulphide ofiron, and they lose color when dried.

Lucke (1935) called attention to local accumulationof black mud in Barnegat Bay, New Jersey, in water
only a few feet deep.
Stockdale (1939, p. 38) wrote concerning the Chattanooga shale of Kentucky and Tennessee:
Evidence strongly points to its being a shore or near-shore
facies formed on the south shore of the Late Devonian-Early
Mississippian sea which advanced southward upon a very low,nearly flat land surface.

CHATTANOOGA SHALE

merits for deep and shallow water. The thin bedding
and high organic content have been used to support
both hypotheses.
A summary of a number of published explanations
relative to the origin of black shale and of the factorsthat must be considered was given by Twenhofel(1939). Later Trask (1951) presented a review ofthe depositional environment of black shale at a synposium on the paleoecology of shale and evaporite deposition held by the American Association of Petroleum Geologists. Trask's abstract is here set forth inits entirety because it has not been previously printed
in a readily available form; his style is preserved:
Depositional environment of "black shale
Black shale is characterized by:
1. Shaly structure, commonly fissile or thin-bedded,
2. Very fine-grained size of constituent particles,
3. High organic content,
4. Black or dark color,
5. Uniform character throughout considerable areal andvertical extent,
6. Absence, scarcity, or dwarf nature of fauna,
7. Low content of calcium carbonate, relatively high content of iron sulphide and varying quantities of phosphate and iron carbonate.
To account for these features the following inferences could
be considered:
1. Deposition in a basin, marine or brackish, in which subsurface water is stagnant and is in a state of reduction,
2. Long continued density stratification of water in basin,
3. Orogenic quiet for material length of time,
4. Narrow seaward outlet of basin,
5. Shallow sill at outlet, or basin located in warm-temperature or warm climate,
6. Intermediate depth of basin, but depth probably is notcritical,
7. Adequate replenishment of surface water to support
abundant life,
8. Warm-temperature and humid or semi-humid climate,
9. Relatively rapid rate of supply of terrigenous constituents,
10. High initial water content of sediments with resulting
compaction of order of 90 per cent,
11. Low relief of land adjacent to sea.
The stratigraphic relationships of black shale suggest deposition :1. On the seaward rather than on the landward side ofgeosynclinal basins,
2. At a time materially in advance of final orogenic destruction of the geosyncline.

J. M. Schopf believes (oral communication) thatthe mud from which the black shale was derived could
hardly have been black, but must have been brown,
because of the abundant microscopic plant particles.
As the plant matter altered under reducing conditions
the rocks became black in much the same manner that553638 61

559

brown peat changes to black lignite. For simplicity,
however, and to avoid confusion, the unconsolidated
sediments are referred to throughout this report asblack muds.
INDICATIONS OF DEEP-WATER ORIGIN OF THE SHALE

In our studies of the Chattanooga shale in Tennessee and nearby areas, we were impressed by a combination of circumstances that point strongly toward ashallow-water origin. But before presenting arguments for that belief, it seems wise to comment onfour characteristics that, at first thought, suggest deep
water. These are the remarkably uniform fine-grained
character of the sedimentary rocks, the apparent absence of ripple-marks and scour channels, the preservation of carbonaceous plant material (which implies
stagnant and tranquil water) and the presence ofphosphatic nodules and lag-concentrates. Each ofthese is considered in the following paragraphs.
The remarkably uniform -fine-grained character ofthe sedimentary rocks. If the only source area for
sediment in the Chattanooga sea were an extensive
peneplain more perfect than any that exists today, ifthat peneplain were formed largely on limestone andcovered by a mantle of soil and vegetation, and if itwere drained by small or sluggish streams, then only
fine sediment could be expected to reach the Chattanooga sea. The thin layers of coarse and fine siltthat make up the black shale, which are microscopic
in thickness and which are often interpreted as indicating deep water, are probably better explained byassuming that the bottom waters were subject to gentle
but frequent agitation. This agitation may have been
insufficient to aerate the bottom water, yet sufficient toshift the mud particles slightly, transport them shortdistances, and sort them into minute laminae.
A notable characteristic of the shale is the lack ofcontinuity of individual laminae. Microscopic studyof the dense black shale shows that laminae of quartz
silt pinch and swell and even disappear within thelimits of a thin section. Attempts to correlate mostof the siltstone laminae from outcrop to outcrop havebeen unsuccessful. Seemingly, if this sediment had
accumulated in deep and quiet water the silt layers
would be much more persistent.
The apparent absence of ripple-marks and scourchannels. The absence of ripple-marks in most of thematerial appears to result from the fact that the muds
were too fine grained to have retained ripple structures, even if such structures ever existed. In reality,
however, the thin sandstone beds that are present
locally in the shale do show small ripple-marks at
many places. Even scour channels, cutting a foot or60

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

more into the underlying shale, have been observed at
a few places. These are in different parts of the formation and, had a special search been made for them,
many more would doubtless have been found. Two
examples of such scour channels are locality 101, near
Woodbury, and locality 107, near Manchester. Obviously the absence of ripple-marks and scour channels cannot be used as an argument that the shale
formed in deep water.
The preservation of carbonaceous material, which
implies stagnant and tranquil water. The mud musthave accumulated in water that was stagnant, unoxygenated, and reasonably quiet, but it is unnecessary
to assume that the water had to be deep. Pepper anddeWitt (1950) showed that Upper Devonian blackshales of New York are interbedded with shallowwater sandstones and shales. Stagnant conditions
could be explained by assuming that a shallow area ofdeposition was partly separated from other areas bysubmarine bars that inhibited circulation and caused
a stratification of the water, as in modern fjords.
However, the differences in size and other characteristics between fjords and the sprawling Chattanooga sea
are so great that any such analogies are not entirely
warranted. Actually, a sea as extensive as the Chattanooga and as far removed from the open ocean(pi. 14) might well have been stagnant without having
been barred. Moore's suggestion (1949, p. 32) that
an abundant growth of sea weeds could have chokeda shallow sea and caused stagnation is much more
appealing to us than the assumption of a barred basin,
either deep or shallow. In such a sea, ample carbonaceous matter is also available for accumulation on thebottom.
Keulegan and Krumbein (1949) showed by mathematical analysis that a gently sloping sea bottom, if
sufficiently widespread, will cause incoming waves tolose their force so gradually that at no place do they
break or otherwise produce sufficient motion of thewater to stir up the bottom muds violently. The
Chattanooga sea was so widespread, and the submerged peneplained surface was so smooth, that theconditions postulated by Keulegan and Krumbein may
well have prevailed. If any part of the sea was deep
enough and sufficiently extensive to permit large waves
to form, the waves may well have lost their force by
the time they reached the area where the black muds
might be disturbed.
The presence of phosphatic nodules and lag-concentrates. Phosphorite is known to be accumulating on
the sea bottom in various places where normal detrital
sedimentation is not taking place (for example, Dietz
and others, 1942) and where the water is several hun-dred to several thousand feet deep. This fact has
been used by Rich (1951b, p. 2025-2027) in support ofhis thesis that black shales like the Chattanooga haveformed in the relatively deep water of his fondo environment. It appears, however, that much remains
to be learned regarding the conditions that permit theaccumulation of phosphate in sedimentary rocks. The
mere fact that phosphate deposition can be recognized
today only in deep water seems to us an insufficientreason to suppose that all phosphate in the past has
accumulated under similar conditions. Rich (p. 2033)
made a special point that the basal sandstone of muchof the Devonian black shale sequence is a lag-concentrate. At many places in the Tennessee area, however,the basal sandstone contains phosphatized fragments
and other material that can be identified as having
been derived from the immediately underlying rocks.
Other constituents of the sandstone, such as fragmentsof conodonts, bones, and plants, were presumably
washed or floated in and added to the local residualmaterial. It seems clear that the basal sandstone, forthe most part, is made up of locally derived material
such as would be expected near the edge of an encroaching sea.
INDICATIONS OF SELAIXOW-WATER ORIGIN OF THE
SHAXiB

In contrast with the f oregoing characteristics, whichmight suggest a deep-water origin of the shale, several
circumstances are collectively seen to require a shallowwater origin. These are: (a) The Chattanooga shale,or its thin basal sandstone, lies directly on the unconformity; (b) the shale contains sedimentary featuresindicative of a shallow-water origin; (c) the blackshale beds overlap to extinction, so that most parts ofthe formation lie on the pre-Chattanooga rocks; (d)the black shale does not grade upward into shallowwater sedimentary rocks; (e) since Precambrian time
most of the area in which the Chattanooga shale ispresent has been one of shallow-water sedimentation;(f) the succeeding Mississippian sea, generally considered shallow, was more widespread and thus presumably deeper than the Chattanooga sea; (g) linguloid brachiopods are common in the black shale. Eachof these circumstances is discussed in the following
paragraphs.
The Chattanooga shale, or its basal sandstone, lies
directly on the unconformity. Attention has beencalled to facts indicative of a near-shore shallow-waterorigin of the basal sandstone. Of especial significanceis the presence of black shale within or even beneaththe basal sandstone, suggesting that accumulation ofsome of the shale also began soon after submergence.

CHATTANOOGA SHALE

As the sea spread slowly over the low land, some ofthis sediment must have accumulated in water only
a few feet deep, for nowhere is there evidence that thesurface slopes were other than extremely gentle.
If it is to be argued that the mud did not accumulate until the water was deep, whatever is meant by"deep," the absence of sediment that normally would
have accumulated before the water was deep must be
explained. If the sea had been there long before theblack mud started forming, as suggested by Rich
(1951b, p. 2035), there should seemingly be a basal
concentration of bones, shells, spores, wood, conodonts,
and other insoluble parts of organisms which lived in
the sea or drifted into it, and which were not derived
from the underlying rocks. It is even more difficult
to believe that all the detritus brought into a shallow
sea was swept along the bottom so completely out of
the region that no local patches of the sweepings wereleft. It is also most unlikely that the first deposition
in deep water would then have been the thin bed ofsandstone, which is so intimately associated with theblack shale and which is made up largely of particles
derived from the underlying rocks.
Only the Hardin sandstone member and the impure
phosphate shale, both restricted chiefly to the southwestern part of the area studied, could possibly be interpreted as concentrations of widespread sweepings.
It is entirely unreasonable to assume that the detritus
from the large area of these studies was transported
to these relatively small areas or still greater distances
northeastward to regions of more abundant sedimentation. The phosphatic shale, moreover, is apparently
composed chiefly of materials of local origin. Furthermore, if these local facies were concentrations from awide area, it is likely that they would have accumulated in the deeper parts of the sea and would later
have been covered by a thick deposit of mud. Instead,the area of the Hardin sandstone member and thephosphatic shale has less of the typical black shale
than does central Tennessee a condition suggestive ofshallower rather than of deeper water.
The shale contains sedimentary features indicativeof a shallow-water origin. The perfection of lamination and high degree of sorting suggest that the muds
were agitated repeatedly but gently. The individual
laminae have such sharp upper and lower boundaries
that simple gravitational settling of muddy water
could hardly have produced them, whereas constantreworking and winnowing could do so. Lenses of silttone or sandstone, ranging from those that do not extend across a thin section to others several feet long
and a few inches thick (for example loc. 108), arealso hardly expectable under conditions of simple
553638 61

661

gravitational settling in deep water. In the Flynn
Creek cryptoexplosive region the abnormally thickaccumulation of black shale seems to indicate, as already mentioned, that the muds were constantly being
shifted along the sea floor so that they filled any low
places. In a few places scour channels a few feetwide have been seen in the shale, suggesting local currents strong enough to remove a few inches of thesoft mud. In one small area where the Center Hillbentonite bed is absent, gentle marine planation seems
to have removed some of the uppermost beds of the
Dowelltown member. All these evidences of bottom
agitation are perfectly compatible with a shallowwater hypothesis, but some of them fit into a deepwater hypothesis with difficulty.
Pepper and deWitt (1950) showed that similar
Upper Devonian black shales in New York state areinterbedded wtih shallow-water sandstones, and thesame appears to be true in the Tennessee area on asmaller scale, notably in and near Hardin and Wayne
Counties, where the shale is interbedded with poorly
sorted crossbedded phosphatic sandstone that appears
to be of shallow-water origin.
Because the successively higher ~beds of ~black shale
overlap the lower ones, most of the shale succession
lie on the pre-Chattanooga rocks. The lowest beds atthe various outcrops range in age from early Late
Devonian to the very latest Devonian, depending on
the apparent time of submergence. The almost complete absence of other types of sedimentary rocks ofChattanooga age below the black shale suggests
strongly that almost everywhere, regardless of thetime of inundation, black mud started accumulating
almost immediately. Had sufficient time elapsed between submergence and the first black mud deposition
for the sea to become "deep," it would be surprisingindeed that no "shallow" water beds are present. In
the almost universal absence of any other sediment between the black shale and the basal unconformity, we
are impressed with the evidence that, as the sea crept
slowly landward, black mud was the first sedimentthat accumulated.
The black shale does not grade upward into shallowwater sedimentary rocks. If the black shale accumulated in deep water, it would expectably grade upward
into a succession of shallow-water sedimentary rocks,
but no obvious succession of this sort has been foundin the Central Tennessee area. If, indeed, the top of
the shale is bounded in many places by an obscure unconformity, as believed by Hass (1956, p. 23), thenthe proponents of a deep-water origin must explain
either why no shallow-water sediment accumulated
while the sea was shoaling or how it was all removed

62

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

so completely while most of the black shale was left
with a smooth upper surface.
Since Precambrian time, most of the area in which
the Chattanooga shale is present has been one ofshallow-water sedimentation. Throughout the central
Tennessee area, the Paleozoic sequence consists chiefly
of fossiliferous limestones and shales and coal-bearing
sandstones and shales. It is generally accepted among
geologists that the widespread limestone deposits of theeastern interior of the United States accumulated inrelatively shallow seas in which many forms of life
flourished. Many of those limestones are present in the
Nashville arch area of central Tennessee. That archhas been an intermittently rising area at least since early
Paleozoic time, as indicated by the thinning or absenceof several of the Paleozoic formations over it (Wilson,
1949, p. 327-332), and even to the present time, as
indicated by more recent uplifts. It is unlikely thatduring Chattanooga time, and that time only, the area
reversed its tendency to rise and sank enough to be
deeply submerged. It is still more unlikely that deep
water covered the region as a result of a world-wide
sudden rise of sea level.
The succeeding Mississippian sea, generally considered shallow, was more widespread and presumably
deeper than the Chattanooga sea. The limestones andrelated rocks of Mississippian age cover a larger area insoutheastern United States than does the Chattanooga
shale. This suggests a widespread flooding that would
have caused the water in the black shale area to be
somewhat deeper than during Chattanooga time. Yet
the Mississippian limestone and chert deposits are generally considered to have formed in an epicontinental
sea that was shallow, clear, and teeming with life. Possibly, however, the most significant difference between
the Chattanooga sea and the Early Mississippian sea
was the degree of connection with the open ocean
distinctly limited and perhaps distant during Chattanooga time but much less restricted during Mississippian time.
Linguloid brachiopods are common in the Ulackshale. Many people have suggested to us that thepresence of numerous Lingula in the shale is a strong
indication of shallow-water origin. In this connection,
Cooper (1957, p. 265) stated "* * * in modern seas all
known species of the brachiopod Lingula are restricted
to shallow waters, usually shore zones subject to tidal
action. The genus to date has not been taken fromwaters deeper than 23 fathoms." He cites evidence (p.
260) that some of the Devonian Lingula must have
lived in a brackish near-shore environment and concluded (p. 261) "* * * insofar as the Middle Devonianof eastern United States is concerned, paleogeographic
and faunal evidence indicates a shallow-water andnear-shore environment." Some geologists (oral communications) have expressed a reluctance to project
present-day ecological conditions so far into the past,
but we are impressed by the arguments of Cooper andbelieve that the Lingula offer strong evidence of ashallow-water origin of the Chattanooga shale.
Each of the foregoing circumstances suggests thatthe mud accumulated in shallow water; combined they
appear to offer compelling evidence that the water was
shallow. By contrast, several of these circumstances
will not fit into a deep-water hypothesis. The assumption of deep water involves such serious difficulties in
explaining the known facts that far more problems are
created than are solved.
Although we know of no way of calculating thedepth of water at an appreciable distance from shore,
we believe it was only a few tens of feet, quite likely
less than 100 feet. We believe that, in some places near
the shore, accumulation of the mud must have begun
when the water was only a few feet deep.
MAURY FORMATIONThe Chattanooga shale is overlain abruptly by a unit
of unusual appearance, commonly only 1 to 4 feet thick,that has been variously considered a part of the Chattanooga shale, a part of the next overlying formation,
or a separate formation. Its typical green color, its
lower resistance to weathering, and its distinct lithologic character all set it apart from the adjacent strata(pi. 135, C). Hass (1956) considered this unit to be
for the most part of Early Mississippian (Kinderhook)age.
In spite of its thinness, it seems best to treat theMaury as a separate formation for several reasons. In
the first place, it is distinctly different lithologicallyfrom the underlying and overlying strata. Secondly,
it is clearly not a part of the Chattanooga shale, fromwhich it is probably separated, at least locally, by an
obscure hiatus. Thirdly, it cannot properly be considered a basal member of the Kidgetop shale, as classedby the Geological Survey (Wilmarth, 1938, p. 13221323), prior to these investigations, because it is equallya basal unit of the Fort Payne chert or of the New
Providence shale. Finally, its distribution is different
from any of the adjacent underlying or overlying formations. Bassler (1932, p. 145) described its relation
by stating "[It is] present in many places irrespectiveof the age of the rocks following it, so that it doubtless
represents the introductory stage of the succeeding
formation no matter what that may be." We would,

63

MAURY FORMATION

however, change his word "age" to "lithologic character."
HISTORY OF THE NAME

The name Maury was first applied to this distinctive
bed by Safford and Killebrew (1900, p. 141) who
wrote:
Besting upon the Black shale is a bed of green or greenish
shale from a few inches to four or five feet in thickness. The
bed is well developed in Maury County and hence the nameabove given to it.

Safford and Killebrew apparently intended that theMaury be treated as a formation, as did Stockdale(1939, p. 49-51). Several writers, however, have considered it a part of the Chattanooga shale (Hayes,
1892,1894a, b, c, d, 1895; Hayes and Ulrich, 1903, p. 2;
Galloway, 1919, p. 55; Jewell, 1931, p. 37-41; Born and
Burwell, 1939, p. 48). Others have considered it, atleast in part, a basal member of the next overlying beds
(Bassler, 1932, p. 143-144; Miser, 1921, p. 24; Swartz,
1924). Campbell (1946, p. 885, 890, 895-900) subdivided the beds that have commonly been termed
Maury into smaller discontinuous units to which heapplied the terms Eulie, Westmoreland, Maury and
New Providence. Campbell's subdivisions are not recognized in this report, in the belief that present knowledge of the distribution and relations of the units isinadequate to warrant the naming of such thin andsporadic units.
SUGGESTED STANDARD LOCALITY

As no definite type locality was designated by Safford and Killebrew, a suitable standard outcrop of theMaury formation was searched for in Maury County,
Term. But good outcrops of the Maury formation inthat county are scarce, and none was found that is bothwell exposed and reasonably typical of the formation.
Consequently, an exposure in southeastern Williamson
County (loc. 185), only about 5 miles from the northeast corner of Maury County, was selected as a standard section for the Maury formation. The exposure
is in a steep stream gully about 50 feet south of asecondary road, 3 miles east of Bethesda and 1.2 miles
east of Cross Key, near the top of the west slope of
Pull Tight Hill. This locality is about a quarter of amile east of the east edge of the Bethesda topographic
quadrangle but is included on an extension of the 1949
edition of that map. The Maury formation is here well
exposed in sharp contact with the underlying Chattanooga shale and the overlying Fort Payne chert (pi.
16J., fig. 14). The geologic section as measured at thisoutcrop is given below. The conodont determinations
are by Hass.

Standard section of the Maury formation near Cross Key,
Williamson County, Tenn.
Fort Payne chert
Feet
Limestone, cherty, fossiliferous; basal contact undulating. To top of hill, about
50
Maury formation:
Siltstone and claystone, grayish-yellow, green to
greenish-gray, glauconitic; near top a thin unit has
a distinctive blue-green color; lower 0.3 foot isdark gray to greenish black. Phosphatic nodules
several inches in length are scattered throughout
but are more abundant in a bed of variable thickness 0.3 to 0.9 foot above base; smaller nodules, ofabout 1 inch, are common in upper 0.1 foot. The
dark-gray claystone at the base can be readily distinguished from the Chattanooga shale by the easewith which weathers and breaks out
1.5
Chattanooga shale:
Gassaway member:
Shale, black, tough; phosphatic nodules scatteredthroughout. Following conodonts found:
Hindeodella sp. A and Spathognathodus aculeatus in upper 1 foot; Spathognathodus
inornatus in lower half foot
1.6
Shale, black, tough. Palmatolepis glatira, P.
perlotiata at 0.8 to 0.9 ft. below top of interval- 2.1
Siltstone or claystone, dark-gray; conodonts
abundant, including the two above and thefollowing diagnostic ones: Ancyrognathus &tfurcata, Palmatodella delicatula, Palmatolepis
gracilis, P. quadrantinodosa, P. subperlobata_ *0.1
Shale, black, tough1.6
Total Gassaway member_ ___Dowelltown member:
Claystone _ _____ ______________
Center Hill bentonite bed _____________
Claystone _______________________
Sandstone __ ___________
Claystone, having thin interbeds of black shale.
Contains following diagnostic conodonts: An~
cyrodella sp. fragments, Ancyrognathus euglypheus, A. sp. fragments, Palmatolepis subrecta,
P. unicornis, P. sp. fragments _________
Shale, black, tough ________________
Covered__ ____

5.4
0.45
0.05
0.2
0.2

43
7.0
1.0

Total Dowelltown member exposed ______ 13.2
Total Chattanooga shale exposed _______ 18.6
Limestone.
GENERAL DESCRIPTION

The Maury formation consists chiefly of various
proportions of greenish claystone, siltstone, shale, andglauconitic sandstone. At most places it contains abundant nodules of phosphate. Regionally the green color
and the nodules are the unit's most distinguishing
characteristics. Typically the lower part of the formation has one or two layers composed almost wholly ofphosphate nodules of many shapes and sizes (pi. 165).
Less abundant phosphate is scattered throughout theformation.

64

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

SYSTEM SERIESFORMATION(THICKNESS,
IN FEET)THICKNESS,
IN FEETSECTION^^^A
Z

Fort Payne chert)IC~S'CDlCIDi<

100 +CID 1CD I CD,CI:<

DESCRI PTION

OF

ROCKS

0.5

Chert and limestone, interbedded. Lower 3.2 feet is bedded grayish-yellow chert, having a bed of gray nodular cherty limestone,
0.2 to 0.6 foot thick, at the base.
Slightly irregular basal contact. Only the basal part of the formation is represented.

n Q
U.o

Mudstone, greenish-gray; distinctive grayish blue green at top;
somewhat phosphatic. Subspherical phosphate nodules about
0.1 to 0.2 foot in diameter disseminated throughout but moreabundant in upper 0.1 foot; larger nodules sparsely scattered.

0.4±

Mudstone, greenish-gray. Abundant ellipsoidal and kidney-shaped
nodules as much as 1 foot in length.
This unit is not well defined, and may be only local.

0.3

Mudstone, olive-gray to dark greenish-gray. Scattered subsphericaland a few larger ellipsoidal phosphate nodules.
Sharp basal
contact.

0.6Black shale and interbedded gray shale, siltstone, and sandstone.
Upper 5.4 feet is the Gassaway member consisting chiefly of
massive black shale having a very few small phosphate nodules
scattered in upper 1.6 feet.
Lower 13.1 feet is the Dowelltown
member, consisting of dark-gray siltstone and sandstone, andsome black shale.
Only the upper part of the Gassaway
member is shown.

3 'CD'CID iCI5 ' C3 , C

CD'OiO'OiC
c
Q_

03

Q-

Q.
Q.

PE^fr^Pl^l^l^^ I^.

7^5iH^^^^

in
in
CO

^^Zr^ZHfZPVfZ-r^rr-L. . irT^irT^j_-r=

inin^^^^^^CO,_<u

Maury formation
1.5

O

S3SS81S-^iz-n_u rt_^-r=_L-r.
.
. ' . __
jpjj-r^j-r-r--^r^^^pCO^-^^^^^^^^^^^-:r=^±:r^^±:^:

5

z
Z
O

~T~ ' ^~ '

c
'E
|
L.

UJ

O

~ '

Chattanooga shale
1 Q C
io.o
-»____Q.
"^^^^

FIGURE 14. Standard section of the Maury formation, locality 185 near Cross Key, Williamson County, Tenn.

At many places a few inches of gray claystone is ator near the base of the formation. At first sight itclosely resembles the black shale of the Chattanooga,
but it can be distinguished from that shale by its
slightly brown hue, its more rapid weathering, and its
lesser induration it responds to a hammer blow with adull thud, but the black shale produces a ringing noise.
Locally a little black shale lies just above the basal
bed of gray shale. Commonly it is interbedded withthe phosphate nodules, takes the place of the nodule
layer where that layer pinches out, or overlies the
nodule bed. In general appearance this shale is identical to the Chattanooga shale, although it contains a
different conodont fauna (Hass, 1956, p. 24). At thoseplaces where the gray claystone or other distinctive
bed of the Maury formation does not separate thisblack shale containing Mississippian conodonts fromthe black Chattanooga shale, it can only be distinguished from the Chattanooga by its fossil content.
The pinching and swelling of the beds in the Maury
formation is illustrated in figure 15, a drawing of an
outcrop near Nashville (loc. 203A).
This example shows that if one examined drill coresor exposures only a few feet wide, the lower 2 feet of

the Maury would be interpreted inconsistently in theabsence of paleontologic information.
The upper part of the Maury formation is commonlya claystone that weathers into hackly chips not fissile
enough to be called shale. On fresh exposures the claystone is greenish gray; on weathered surfaces it islight green, olive green, or light blue green. Alongmost of the eastern and southern edges of the basin
glauconite grains are rarely visible in either hand
specimens or thin sections, but the green color may
result from "pigmentary glauconite," a form describedby Cayeux (1897). X-ray study in the survey laboratory indicates that the bright blue-green shaly "chips"that are common at the top of the Maury probably
contain glauconite. These chips are commonly an inchor two long and are restricted to about the two top
inches of the formation.
The claystone and siltstone and other rocks of theMaury formation weather more rapidly than most of
the overlying and underlying rocks and yield a clayeymaterial that is slippery when wet. On some unimproved roads, where outcrops are often poor, agreenish mud hole in the road and a few phosphate

MAURY FORMATION

65
Maury
formationi i i iHORIZONTAL AND VERTICAL SCALE

FIGURE 15. Sketch showing apparent interfingering of the Maury formation and the Chattanooga shale. Two-foot wedges of black shale andphosphate nodule-bearing claystone pinch out within 50 feet. Black shale wedge at center is considered part of the Maury formation, but
at the west end, and for 100 feet beyond, it is lithologically indistinguishable from black shale of the Chattanooga. Locality 203A.

nodules in the soil are sufficient to identify the positionof the Maury.
Along much of the western edge of the NashvilleBasin the Maury formation contains abundant glauconitic sandstone. At most places this overlies the phosphate nodule layer, but in some places it also encloses
the nodules and extends to the base of the formation.
At places where the Chattanooga shale is absent thelower part of the Maury is characteristically a glauconitic sandstone that contains granular or nodular
phosphate.
In parts of the valley of Swan Creek, especially inLewis and Hickman Counties, where the Chattanooga
shale is missing, the Maury is composed largely ofphosphatic debris that has been reworked from theformer land surface.
On Red Mountain, between Birmingham and Bessemer, Ala., some of the road cuts show a foot or lessof greenish mudstone underlain by a foot or less of
purplish clay, and this by a few inches or a few feetof sandstone. The fine-grained beds have commonly
been identified as Chattanooga shale. It seems more
likely, however, as reported by Glover (1959, p. 143),that sedimentary rocks of Chattanooga age are absent on
Eed Mountain and that the material in question is anequivalent of the Maury formation. The sandstone isprobably a basal phase of the Maury. These beds areoverlain abruptly by characteristic Fort Payne chert.
PHOSPHATE NODULES

A description of the phosphate by Safford and Killebrew (1900, p. 141-142) is quoted here:
The Green shale is of interest in that it has generally imbedded in it concretions of calcium phosphate. These are roundish, from the size of marbles to that of a man's head, and in
kidneylike, cakelike, and gourdlike forms of various sizes.
They may be seen tightly packed together with little of the
shale, as if so many cannon balls, in a layer from 8 to 10, or
exceptionally 18 inches in thickness; or else loosely disposedin the greenish shale, which itself is more or less phosphatic.
The concretions, when broken, give out a strong fetid odor andshow shells of lingulae. They contain 50 to 65 per cent ofcalcium phosphate. The bed is well developed in parts of Perry
county.
Kidney forms of the above kind are now and then seen imbedded in the underlying Black shale.

The tightly packed nodules, where present, are in
the lower part of the formation (pi. 13(7), and where
the concentration is greatest they have their greatest
variation in shapes and sizes. The loosely disposed
phosphate is typically in the upper part of the formation where it assumes marblelike or thin platelike
shapes. The platelike masses are as much as several
feet long and are commonly parallel to the stratification, but in places they are at various angles to thebedding.
The thickness of the bed of tightly packed nodules
is commonly about 6 inches to 1 foot but differs greatly
in short distances. One of the best exposures is in a
deep highway cut along the north" approach to Hurricane bridge in DeKalb County, Tenn. (loc. 68), where
the nodule bed ranges in thickness from about 3 inches
to 2 feet (pi. 16Z?). At an outcrop in Jackson County(loc. 27) it is 2 feet thick at one place, but 50 feetaway along the outcrop the nodules are absent. At
a few places along the northeastern edge of the Nashville Basin two nodule layers are present, separated
by a few inches of black shale (for example, loc. 27).
The matrix of the phosphate nodule masses differs
greatly from place to place. At some outcrops the
nodules are embedded in greenish siltstone or sandstone that commonly is glauconitic. Along the northern and northeastern edges of the Nashville Basin,
where glauconite is sparse or absent, the matrix is abadly contorted impure dark-gray shale that is wedged
between the nodules. In the western part of the area
the abundant nodules are associated with a coarse
glauconitic sandstone, which is in the lower part andwhich is grayish green to dusky blue green in color.
Where associated with fine sediments the nodules
commonly have a massive appearance, but where they
are associated with glauconitic sandstone they nor-

66

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

mally contain a large percentage of easily recognizedglauconite and quartz. Microscopic examination showsthat both types contain abundant grains of the associated rock. Some nodules contain abundant oolites ofphosphate commonly less than 1 mm in diameter;others have tiny spheres which are probably remnantsof oolites but which are now either hollow or are filledwith quartz, calcite, or pyrite.
A large proportion of the nodules contain one ormore fossils that probably served as nucleii aroundwhich the calcium phosphate accumulated. Amongthe fossils that have been recognized are linguloid
brachiopods, conodonts, cephalopods, crustaceans, bone
fragments, and plant remains. Lloyd G. Henbest(written communication Feb. 10, 1953) of the Geological Survey identified probable spumellarian typeradiolaria in some of the nodules; though poorly preserved, they show little or no fragmentation or deformation by compaction.
Microscopic study shows that the massive nodules
from the eastern edge of the basin contain abundant
minute grains of quartz, mica, calcite, and pyrite. The
average diameter of most of these particles is about
0.005 mm, which is about the minimum size of silt
grains. Some grains are even smaller, in the size
range of clay. These grains are about the same kindand size as those that make up the associated claystoneor shale. Locally the quartz, calcite, and pyrite are concentrated in the spherical vacuoles, which are 1 mm orless in diameter. Similar study of a nodule from acoarser glauconitic sandstone matrix (loc. 196) showsat least 50 percent of the nodule to be inclusions ofgrains that make up the enclosing rock.
No detailed study has been made of the phosphateminerals in the nodules. Presumably the phosphatic
part consists of cellophane, a variety of apatite.
Chemical analyses of nodules taken at random fromthe conspicuous bed at locality 68, along the northapproach to Hurricane Bridge over Center Hill Reservoir, show about 30 percent P2OS (table 10, p. 70).
The wide areal distribution of the phosphate nodule
layer is one of the most remarkable characteristics ofthe Maury formation. The nodule layer is absent,
however, in parts of the area studied. It is absent at
most outcrops along the eastern edge of the NashvilleBasin from southern DeKalb and White Counties
southwest to the Alabama State line, a distance of 75
miles. It is also absent in the southern part of thebasin as far west as the vicinity of central Giles andMarshall Counties, though at a few outcrops a few
small phosphate nodules and thin phosphatic layers
were observed. Farther south the nodule layer ispresent in outcrops in northern Alabama; it thins east-

ward in the Sequatchie Valley. It is seen consistently
in cores of water wells drilled in the vicinity of Huntsville, Ala. (P. E. LaMoreaux, oral communication)and it is present at many places farther south in
Alabama.
The nodule layer must result from conditions thatexisted widely in the Early Mississippian epicontinental sea, and it seems likely that everywhere thelayer is about the same age.
It is probable that the nodules formed on the sea
bottom simultaneously with the slow accumulation of
the mud, and shortly afterward. The abundance ofthe nodules (pi. 165) seems to preclude the likelihoodthat they were formed long after deposition by amigration of phosphatic matter in the formation oreven in the underlying Chattanooga shale. Seemingly
the nodules are a chemical precipitate from the sea
water, but the tabular masses that cut across the bedding seem to result from local migration and redeposition of the material after burial and compaction.
EXTENT AND THICKNESS OF MATTRY FORMATIONThe Maury formation is present at every examined
outcrop where its stratigraphic position is exposed,
and it continues without known exception across all
the areas in the region of this study where the Chattanooga shale is absent 8. Jewell (1931, p. 40-41)
stated that the Maury is absent in most of Hardin
County, Tenn., but we have recognized it at every outcrop of Chattanooga shale in that county, as elsewhere.
Northward into Kentucky the blue-green mudstone
becomes thinner but the phosphate nodules continue
across the State and even into Indiana, where Campbell assigned them to the Falling Run member of his
Sanderson formation. In much of Kentucky, however, the only recognizable Maury is a layer of phosphate nodules at the base of a succession of greenish
or bluish shales that have been generally called the
New Providence shale.
The thickness of the Maury formation commonly is
between 1 and 4 feet, though its thickness is known torange from a few inches to at least 7 feet. At mostplaces around the Nashville Basin it is about 2 to 4
feet thick. Some of the thinnest observed outcrops
are in and near the northwestern part of Davidson
County where it is a phosphate-rich glauconitic sandstone about 4 to 12 inches thick. On the south edge
3 The only outcrop in Tennessee observed during this study where
the presence of the Maury formation is in doubt is locality 88 at
Horseshoe Bend on Caney Fork, now below normal pool level of Center
Hill Reservoir. On the basis of conodonts found between 1.7 and 2
feet below the Fort Payne chert, Hass (1956, p. 30) assigned no beds
to the Maury. The senior author of this report believes the topmost
1.7 feet of beds, which have a greenish color, should be assigned to
the Maury.

67

MAURY FORMATION

of Chattanooga, at St. Elmo, it is about 5 feet thick,as it is at several outcrops southward for 50 miles tothe vicinity of Fort Payne, Ala. In a highway cut at
Blanche, DeKalb Co. Ala., where the formation dips
about 80 to 85 degrees, it is about 7 feet thick. An
unusual feature at the Blanche outcrop is a 2-foot bedof black shale, 3 to 5 feet from the top of the formation.
At a few places, where the Maury formation grades
into an overlying shale, its upper contact can not be
positively located. Thus, at one place near Theta, inMaury County, Tenn., (loc. 181), the formation isabout 8 feet thick the basis of an upper limit determined by any satisfactory criterion.
AGE AND FOSSILS

Opinions on the age of the Maury formation havebeen almost as diverse as those concerning the underlying Chattanooga shale, with which it is so closely
associated. Those who have treated it as part of the
Chattanooga have naturally given it the same age
assignment. The following quotation from Campbell(1946, p. 895) not only summarizes some of these views
but illustrates the attention that has been given to thisthin unit:
Safford (1869) included a layer of "kidneys," at the top of
the black shale, as a part of the black shale group of Devonianage. Safford and Killebrew (1900) named the Maury anddefined it as a bed of green or greenish shale from a few inches
to 4 to 5 feet thick, which contains concretions of calcium
phosphate, in a layer 8 to 10, or exceptionally 18 inches thick,and included it with the Mississippian. * * * Swartz (1924)
regarded the Maury as "the broadly overlapping basal bed of
the Ridgetop rather than of the Chattanooga shale, and as acondition not a chronological unit." Bassler (1932, p. 143)
regarded the Maury as the "introductory stage of the succeeding formation no matter what that may be." According toKlepser (1937) and as quoted by Stockdale (1939), the Chattanooga everywhere grades upward into the Maury, and theMaury into the New Providence and Fort Payne. The Chattanooga and Maury are time-transgressing units representing
the basal shore phases (the Chattanooga the more shoreward)of the sea advancing southward. The Chattanooga is in greatpart post-Kinderhook (almost entirely Osagian) ; in Alabama
it is Warsaw, and possibly St. Louis, in age according to Klepser.

As Campbell considered the Gassaway member of
the Chattanooga shale to be of Mississippian age, henecessarily assigned the Maury to the Mississippian.
Hass (1956, p. 23-24) concluded, from a study ofthe conodonts, that in most areas the entire Maury
formation is of Kinderhook (Early Mississippian)age, but in a small area in north-central Tennessee thebasal bed appears to be of very late Devonian age, andin some places the uppermost part is probably of early
Osage age. From this it appears that the 3 or 4 feet of

the Maury formation represents most, if not all,of Kinderhook time. The beds tend to have a moreor less uniform lithologic succession, and at most places
there is no obvious evidence of erosional breaks within
the formation or at its top. It seems likely therefore,that the Maury formation, where more complete, represents the entire accumulation on the bottom of aquiet sea that existed throughout most or all of Kinderhook time. Elsewhere sedimentary beds of that age
are many times as thick.
Other sparse fossils in the Maury formation include
cephalopods, crustaceans, bone fragments, and plantremains. A few Orbiculoidea and Lingula were found,but the very few larger brachiopods that were foundare poorly preserved and are not suitable for specificidentification. Mention has already been made of the
Kadiolaria identified in the phosphate nodules (p. 66).
Except in the nodules, fossils are generally found in
the Maury only with difficulty.
LOWER AND UPPER CONTACTS

The base of the formation is here defined as thecontact between the black shale of the chattanooga andthe greenish gray claystone, siltstone, or sandstone, orthe conspicuous bed of phosphate nodules; where those
beds are absent and black shale encloses or overlies
the main bed of nodules, the contact is at the base of
the lowest conspicuous nodule layer. At outcrops
where the phosphate nodule layer or other distinctive
lower bed of the Maury formation is absent, any blackshale bed that elsewhere contains the nodules or thatwould overlie them, is necessarily classed as Chattanooga shale; only the conodonts would reveal its Mississippian age and thus its age affinity with the Maury
formation (fig. 15). South of Kentucky the contact
is abrupt nearly everywhere. In much of Kentucky
the contact appears more gradational and is moredifficult to identify.
Where the Chattanooga shale is absent and theMaury formation lies on older rocks, it is obvious thatan unconformity is present, and physical evidence of
it is abundant.
It has already been stated in discussing the Chattanooga shale (p. 36) that at some places an inconspicuous erosional surface seems to separate theshale from the Maury formation. At most places nophysical evidence of an unconformity was found,though Hass (1956, p. 23) believed that the change in
conodont assemblages denotes some kind of break insedimentation.
The upper contact of the Maury formation has beenvariously placed. Where the Maury is overlain by ashale formation, the gradation from one to the other68

CHATTANOOGA SHALE, BELATED ROCKS,

is so gradual that in many places it is difficult to selecta satisfactory boundary, as at the Theta outcrop already mentioned (loc. 181). At most such places thephosphatic Maury is either glauconitic or has a distinctive green color, but it is not calcareous. The overlying shale, however, is not phosphatic or glauconitic
but usually is calcareous and is likely to contain subordinate beds of chert. At these places the upper contact of the Maury is placed arbitrarily where the phosphate and glauconite disappear or where shale becomes calcareous, whichever is lower. At some places
a conspicuous chert bed near the horizon where thecontact would be expected constitutes a satisfactory
basal bed for the overlying formation.
Where the Fort Payne chert or its local basal unitof crinoidal limestone overlies the Maury formation
the contact is abrupt. The characteristic brilliant
blue-green shaly chips that are present at many places
at the top of the Maury are also present at many placesin the lower 2 or 3 inches of the Fort Payne (pi. 16C).
Their origin is unknown, but they do not appear to be
reworked chips of a previously deposited bed. Where
both formations are weathered, the contact can usually
be located within a vertical distance of an inch or two
between weathered phosphate nodules of the Maury
and quartz-lined geodes of the Fort Payne.
The lithologic contrast between the soft greenishgray claystone of the Maury formation and the hard
massive chert of the Fort Payne chert is suggestive ofan erosional break at that horizon, but there is no
known evidence of an unconformity. The Fort Payne
chert is a lateral equivalent of the shales that elsewhere overlie the Maury conformably; thus there is
no reason to believe that an erosional break separates
the Fort Payne from the Maury. Instead, the contact
probably represents a relatively sudden change to an
environment that favored the deposition of siliceous
limestone on the sea bottom.
Were there a widespread erosional break at the
top of the Maury formation, it is highly probable thatthe thin unit would have been entirely removed atsome places. As no place is known where it is missing
or where its upper surface is irregular, its continuity
is an additional indication of a conformable contact.
Such irregularities as do exist in the thickness andcomposition probably result from slightly varying
conditions of deposition and availability of sedimentfrom place to place.
SIGNIFICANCEThe Maury formation is believed to be a transitional unit that marks a gradual regional change fromCENTRAL TENNESSEE AND NEARBY AREAS

the poorly oxygenated waters of the Late Devonian
sea to the well-aerated sea of Mississippian time. As
already explained (p. 36), Hass (1956, p. 23) interpreted the paleontologic evidence to indicate thatsome of the topmost beds of the Chattanooga shale
are absent in large areas, but physical evidence of an
unconformity at the Chattanooga-Maury contact isscant. Deposition may have been interrupted locallyby a shallowing of the sea at the end of Devonian timeand perhaps by some warping and planation of thesea bottom. Otherwise deposition seems to have been
almost continuous from the Chattanooga shale to theFort Payne chert or its lateral equivalents.
The significance of the abundant phosphate nodules
and glauconite is not known. Many writers have speculated on the origin and significance of these minerals,
but it is by no means certain that any one of the theories will explain the mineral assemblage in the Mauryor the phosphate in the upper part of the Chattanooga.
As no special studies of these minerals were madeduring the present investigations, no theories areoffered to explain their presence.
The association and stratigraphic significance of
nodular phosphate and glauconite in a thin unit representing an extended period of time was discussed byGoldman (1922). He cited a number of areas whereconcentrations of these two minerals, with a minimumof detrital material, are indicative of important stratigraphic breaks. To what extent this concept can beapplied to the Maury formation is uncertain, but it
is likely that the phosphate was precipitated whenclastic sedimentation was extremely slow, as it iswhere it is being precipitated today (Dietz and others,
1942).
Many writers who have discussed the origin andsignificance of glauconite thought that the mineral isformed in a somewhat reducing marine environmentof slight sedimentary influx (for summary of these
opinions, see Cloud, 1955). In most respects the Maury
formation seems to fit these ideas, though it may be
noted that the glauconite is not apparent in those parts
where the very fine texture of the rocks most strongly
indicates slow deposition but is abundant in areas
where a sandier f acies predominates.
The small amount of clastic material that accumulated during Kinderhook time in the area studied isprobably primarily a result of the increased distancesfrom source areas. At the end of the Devonian period
the epicontinental sea expanded broadly over its peneplained margins and covered all the islands that had
existed in the Chattanooga sea. Source areas, which
had provided only small amounts of sediment in Late

69

ECONOMIC GEOLOGY

Devonian time, were now separated from the area by
a much greater expanse of water. Most of the clastic
sediment that makes up the Maury formation is probably primarily the sediment that formerly made up
surficial deposits of the peneplained areas that were
submerged. Most of this material was probably stirred
up numerous times by currents or waves before final
deposition occurred.
The subsequent onset of more abundant deposition,
chiefly of chert, shale, and limestone, must have beencaused by significant changes in the nature of theepicontinental sea or the surrounding land, or both.
ECONOMIC GEOLOGY

For many years the black shale (locally known as
black slate) has been mistaken for coal, which it somewhat resembles in appearance, and many optimistic
persons have vainly dug into the hillside hoping that
fresh material, farther back from the outcrop, would
be useable coal. Hopes have doubtless been strengthened by the observation that the shale will burn slowly
if thrown onto a fire and will burn in a forge. The
burning, however, results from the organic content
which, when heated, breaks down to form oil and gas,
as discussed later. The remaining rock, or ash, which
has the same shape and size as before burning, amounts
to fully 75 percent by weight of the original rock, ascompared with 15 percent or less in most commercial
coals.
The Chattanooga shale has been used in one small
plant as a source of pigment, but, so far as known tous, it has not otherwise been used commercially.
Locally large slabs have been split and used fordoor steps and flagstones, but it disintegrates withina few years. It cannot be split and trimmed with
sufficiently smooth surfaces to be used as slate.
LIGHT-WEIGHT AGGREGATE

When the black shale is burned under proper conditions, it bloats and becomes light enough either tofloat or almost to float on water. Experiments havebeen conducted in the use of burned shale as a lightweight aggregate for concrete, but the results of such
experiments, so far as we know, have not been published. It is understood that in Sweden light-weightbuilding blocks, having a specific gravity of about
0.8, are made from the carbonaceous Alum shale. If
the Chattanooga shale were ever to be mined for the
extraction of any of its ingredients, the readily available shale residue might well be used for similar lightweight building blocks.
553638 61-

OIL SHALE

The Chattanooga and related black shales have long
been known as low-grade oil shales, but their yield is
so much lower than that of some of the western oil
shales that no serious attempt has been made to extract
the oil on a commercial basis. Grouse (1925, p. 62)
reported that the shale in Kentucky will yield as muchas 16 to 21 gallons of oil per ton and 3,000 to 4,000 cu
ft of gas having a heat value of 337 Btu. He did notstate the locations from which the samples were taken.
Samples taken during the present investigation from39 feet of black shale in Kentucky, at locality 4, wereassayed in the laboratory of the U.S. Geological Survey by the modified Fischer retort method. These
assays show a maximum oil yield of 17.5 gallons per
ton for a 2-foot interval (at the top), an average of
14 gallons for the upper 10 feet, and an average ofabout 10 gallons for the entire 39 feet.
Oil assays of many samples taken in Tennessee during the present study are summarized on plate 17.
Eesults of additional assays were published by Cuttitta (1958, table 9) 4. No obvious relationship was
found between the indicated oil yield and other characteristics of the three black shale units in the Tennessee area. Plate 17 illustrates this point if it is bornein mind that the topmost black shale (upper unit of
the Gassaway member) is the most massive, darkest
in shade, and highest in uranium content and that thelowest black shale unit (lower unit of the Dowelltown
member) is the least massive, lightest in shade, andlowest in uranium content. The gray beds are low inboth uranium content and oil yield.
These assays indicate that the Chattanooga shale ofTennessee is not likely to be exploited as an oil shalein the near future. If, however, large quantities ofthe shale were to be worked for one or more otherconstituents, the oil and gas might be extracted as
by-products.
Although no minimum standards for potentiallyexploitable oil shale have been established in actual
practice, the U.S. Geological Survey uses a 15-footbed that will yield 15 gallons per ton as the lower
limit in calculating oil shale reserves. At present all
significant experimentation in mining and retorting
oil shale is confined to grades yielding more than 25
gallons per ton. As the Chattanooga shale does notmeet even the minimum specifications, it is not currently considered in estimating national reserves ofoil shale.
4 See table 1, page 6, this report, for the stratigraphic identificationof the sample numbers shown by Cuttitta.

70

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

At one time about 10 gallons of oil per ton werereported (Nelson, 1913, p. 159-160) to have been obtained as a by-product in the process of treating the
Chattanooga shale for use as a paint pigment.

Nelson (1913, p. 149-150) mentioned an attempt tomine the so-called black or kidney phosphate in theMaury formation. This unsuccessful venture was near
Boma in Putnam Co.

PHOSPHATEPIGMENT

Phosphate, like oil and gas, is a possible by-productif large quantities of Chattanooga shale were to beprocessed for one or more other ingredients. At mostplaces the lower part of the Maury formation has aphosphate nodule bed, commonly a few inches to 1
foot thick and, if operating conditions permitted, thisbed might supply a profitable phosphate by-product.
Determinations of the phosphate content of thesenodules are given in table 10. (The phosphate content
of a rock is commonly reported either as phosphoricoxide, P2O5, or as tricalcium phosphate, Ca3 (PO4)2;
the latter, known commercially as bone phosphate oflime or B. P. L., is 2.18 times the P2O5 content.)

The only known successful industrial use of the
Chattanooga shale is as a source of black pigment.
Nelson (1913, p. 159-160) reported its use at Nashville where, after the extraction of about 10 gallonsof oil per ton by retorting, this shale was ground andmixed, then made into a "* * * natural carbon paintby adding a sufficient amount of linseed oil and manganese dryer." Later Whitlatch (1948) described asmall plant near Franklin, Williamson County, Term.,that had produced an impure carbon black since 1932.
Unless new and vastly greater demands for such pigment should arise, this use of the Chattanooga shale
appears unlikely on a large scale. As a by-productin connection with some other exploitation of the
shale, the pigment might be manufactured on a muchlarger scale.

TABLE 10. Phosphate content of nodules from the Chattanooga
shale and Maury formation in Tennessee

SULFURIC ACID

LocalityNo.
(table13)

CountyDescription

PsO.
Gas (P 04) a(percent) (percent)AnalystMaury formation

68

DeKalb..

29.9
29.3
33.2

65.2
63.9
72.4

Harry Levine
W. P. Tucker

Chattanooga shale

36
66
60
66

Top 1 ft... ... ..
1-2 ft below top ...
2-2.3 ft below top.
Smith .... Top 1 ft __ .
1.9-3.1 ft below
top.
Putnam.. Several nodules inupper 6 ft.

26.0

The black shale contains about 10 percent pyrite or
marcasite. Quite possibly the large-scale utilizationof the shale for some other purpose would also permit
a profitable byproduct manufacture of sulfuric acid,especially if the other process were such as to requirefine grinding or roasting of the shale.
URANIUM

20.8
23.2
27.3
26.3
28.9

56.7
45.3
50.6
59.5
57.3
63.0

28.0

61.0

Leonard Shapiro
Do.
Do.
Do.
Do.
Do.

This phosphate is about medium grade and is somewhat lower grade than most phosphate mined in western Tennessee, much of which has ranged between 70
and 80 percent B. P. L. As the analyses given in table
10 are of the nodules themselves, the phosphate content of the entire bed of nodules, as it would be mined,
would be somewhat less. In the massive black shale,
which is the richest in uranium of the Chattanooga
beds, the P2O5 content is only 0.1 to 0.2 percent.
The basal sandstone of the Chattanooga shale in
Hickman, Lewis, and Perry Counties locally contains
an abundance of phosphate. This "blue phosphate"
was mined at one time, but its thickness and B. P. L.
content vary to such an extent that it has not been
mined commercially for many years.

SAMPLING

During the course of the studies here reported, chiefly
between 1947 and 1954, about 3,000 samples were takenfrom about 150 outcrops and 75 drill cores. Except inoutlying or fringe areas or places of poor exposures,
most of the sampled outcrops are within 5 miles of one
another, and some are much closer. Much the greaternumber of samples were taken from central Tennessee,
either because shale from other areas was found tohave markedly less uranium or because such factors as
thick overburden, structural complexities, and thinness of strata make the shale of less economic interest.
In 1948 a drilling program to obtain samples of the
shale at depth and at a considerable distance from outcrops yielded four cores from DeKalb and WhiteCounties.
In 1949 a 100-foot adit was driven into the Chattanooga shale near the east approach to the old Sligo
bridge (loc. 79) by the Tennessee Valley Authority
to obtain bulk samples for the Geological Survey forlaboratory experimentation and to learn something of

71

ECONOMIC GEOLOGY

the mining characteristics of the shale. In 1953 thisopening supplied bulk samples for experimental workat Columbia University.
In 1953 a more intensive drilling program was conducted by the U.S. Bureau of Mines for the Atomic
Energy Commission, in cooperation with the Geological
Survey, in order to test one area in detail and to explore other areas. Seventy-one cores were obtained,
all of NX size (2^ inches in diameter). Seven werefrom two sites east of Smithville, Term., that had been
selected by the Bureau of Mines for study as possible
mine sites one site near the Sligo adit, and one on thenorth side of Pine Creek (fig. IT). The other 64 cores
were to obtain samples for uranium analyses, and forgeological information. Of these 64 cores, 36 near
Smithville were at spacings of about a mile or less, 19
along the Northern and Eastern Highland Kirns wereat spacings of 10 to 17 miles supplemented by 2 others
close to one site, and 7 on the Sequatchie anticline wereat irregular spacings. Because these cores have been
the basis for estimates of uranium tonnages and many
have been studied by other investigators and because
most of them are available for future studies, the locations of all the hole sites are shown in figures 16 and 17.
The seven cores from the mine-site localities included
about 50 feet of the overlying Fort Payne chert, andwere subjected to engineering tests (Blair, 1956). The
other 64 cores from the holes drilled in 1953 were sawed
lengthwise into halves and quarters. One quarter of
each core was sent to the Survey laboratory for
uranium analysis, and another quarter was turned overto the Bureau of Mines for permanent storage.
Quarters of 35 cores were given to Dr. T. F. Bates forstudies at Pennsylvania State University, and quartersof 28 cores were given to Dr. P. B. Stockdale forstudies at the University of Tennessee. A few halvesor quarters were supplied to other investigators for
special studies, and the halves or quarters of the remaining cores are retained by the Geological Survey.
Results of the drilling on the Eastern Highland Rim
were reported by Kehn (1955).
DETERMINATION

All the outcrop and drill-core samples were analyzed
for their uranium content in the Geological Survey
laboratory in Washington under the general supervision of Irving May, Frank S. Grimaldi, and Francis
Flanagan. The uranium content of splits of many of
the samples was also determined in other laboratories.
All samples were checked for their equivalenturanium content by standard radiometric methods.
All promising samples, as well as many others werethen further checked by fluorimetric methods. The

fluorimetric methods available in the later stages of thework are believed to produce determinations having aprecision ob about ±0.0005 percent, or 5 parts per million. Many of the samples whose uranium content
had been determined earlier by .the somewhat less precise methods then available, were re-analyzed to thisgreater precision. For nearly all samples from theGassaway member the uranium content was determined by fluorimetric methods, but for a large number
from the Dowelltown member only radiometricmethods were used.
BEIiATIONS

A synthesis of the large volume of analytical data
established the following facts regarding the association of the uranium:
1. The five lithologic units of the Chattanooga shale contain
distinctly different amounts of uranium; the three richest
are those that constitute the Gassaway member, and therichest single one is the upper unit of the member.
2. The uranium content of a given stratigraphic unit is nearly
uniform for distances of many miles.
3. The darkest and most massive of the black shales have themost uranium, and the gray beds and sandstone have theleast.
4. Shale containing phosphate nodules has less uranium than
the nonphosphatic shale.
5. Coalified plant remains contain more uranium than any
other type of rock.

Analyses of the large number of outcrop and drill
core samples from the Eastern Highland Rim show
strikingly the uniformity of the uranium content ingiven stratigraphic intervals over large areas. For 50
miles, from central DeKalb County to southern Coffee
County, the uranium content of the shale shows nomarked departures from that shown in table 11.
TABLE 11. Average thickness and uranium content of the lithologic
units of the Chattanooga shale on the Eastern Highland Rim,
between DeKalb and Coffee Counties, Tenn.
Unit

Thickness(feet)Uranium(percent)

Gassaway member______---_---__-_Upper unit (top black shale)__________
Middle unit (upper claystone)_______
Lower unit (middle black shale)_______
Dowelltown member.____________________
Upper unit (middle gray claystone) _ _ _ _Lower unit (lower black shale)..______

14.5
5
2
7. 5
l 15. 5J 9. 5
1 6. 0

0.006
. 008
.004
. 0055
(l)
. 001
. 003

i Thicknesses of the units of the Dowelltown member vary more than the unitsof the Gassaway member, and the average uranium content of the entire member
varies accordingly.

Gamma-ray logs of the Chattanooga shale, if on a
sufficiently large scale, show this stratigraphic controlof the uranium (fig. 18).
ORIGIN AND DISTRIBUTION

The most uraniferous parts of the formation are themost massive, the darkest in color, the most pyritic, and72

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

85°_J ____ x...KENTUCKY: TENNESSEEEXPLANATION.ROBERTSON / S U MN E R.,.,,
Springfield

,

f i57
62

Area underlain by Chattanooga shale
Limit of outcrop
Fault bounding the Chattanooga shale^36'
JtnnrimriTU

^

H

l

T

Area of closely spaced drill
holes shown in figure 17

E

.45

i
j^WILLIAMSONj

Murfreesborop V_ - <' Woodb

\

40

J^*?/

Drill hole
Drilled in 1953

RUTHERFORD f.LC-113A' CANNON / w A B R!'
MAURYj

",

^

fj/K^

\

42"

E N \

"Spencer'.BLEDSOE

Drill hole:.::'^^^^T,^-,^
Mcitfinnvme sVAN: BURE^ ^ \//£K: \ : / ; : :,'Pikeville/ 4^ \ ./<X'-

Drilled by U. S. Bureau of
Mines in 1948

jf1

^iMLTON^/TENJJESSEEALABAMA"'

Center^ FLOY^.CHEROKEE ^- 85°
10

0

10

20

30

40

50 MILESFIGURE 16. Localities of drill holes in Chattanooga shale.

See further explanation on figure 17.

73

ECONOMIC GEOLOGY

6 MILESEXPLANATION*LC-102
Drill hole
Drilled in 1948

Area underlain by
Chattanooga shale

Site of closely spaced holes

26

Drill hole

Drilled by U. S. Bureau of Minesin 1953

Drilled by U. S. Bureau of Minesin 1953

Limit of outcrop
FIGURE 17. Localities of drill holes near Smithville, Tenn.

probably the richest in organic matter. To date nouranium mineral has been found in the shale, and all
attempts to identify a uranium-bearing compound havebeen unsuccessful. Studies of selected specimens haveshown that some organic-rich parts contain more than
average quantities of uranium (as high as 0.033 percent) , whereas pyrite samples do not. Experiments by
Moore (1954) showed that plant matter and low-rankcoal have a strong affinity for uranium in solution.
Breger and Deul (1956) reviewed a large body of
information regarding the association of uranium withorganic matter and concluded (p. 509):
There can no longer be any question * * * that carbonaceous
materials of various types play an important role in the secondary concentration of uranium. * * ********Uranium is not genetically associated with the carbonaceous
substances, but it is collected by these substances during its
migration.

It is generally accepted that the black mud thatformed the Chattanooga shale accumulated in unoxygenated waters rich in plant fragments and sulfur
acids, and it is probable that the sediments accumulatedwith extreme slowness. The paucity of clastic material
resulted from the great distance of any major sourcearea and from the inability of the nearby peneplained
area, which was predominantly of limestone, to supply
much sediment. Organic debris, on the other hand, wasrelatively abundant, being supplied both by sluggish
streams from the land areas and by algae and otherplants that lived on or near the surface of the sea. The
plant matter that sank into the oxygen-poor lower
water was preserved from decomposition. Soluble ironavailable in the sea water combined with sulfide ions toform minute particles of iron-sulfide as disseminationsin the black mud. Uranium probably was brought tothe sea in fairly normal amounts from decomposing
rocks in distant areas, was spread widely in the sea,
was abstracted from the water by the abundant organicsvanv

RADIOACTIVITY. IN COUNTS PER MINUTE

w

.
a?

ag

axv

'ssooa aaiviaa 'HTYHS VOOONVJJ.VHD

75

ECONOMIC GEOLOGY

debris in the bottom mud. The precipitated uranium
is probably thoroughly disseminated as submicroscopic
specks or films on the plant debris.5
Time was probably an important factor in the concentration of the uranium, for the longer the individual
plant particles were exposed to the water, the moreuranium they could acquire. In other words, the slower
the accumulation of clastic mineral matter in the sea,
the richer the mud in uranium. Further, the higher
the ratio of the organic matter to the clastic mineralmatter, the higher the uranium content that may be
expected in the shale.
Geographic location, other factors being equal, probably favored certain areas. Thus, if the chief sourceof the uranium was the crystalline rocks of the southern
Appalachian and Piedmont area, as seems likely, themud closer to the eastern or southeastern shore of thesea would be expected to have a somewhat higher
uranium content. On the other hand, where a greater
quantity of clastic sediment reached the sea, as innortheastern Tennessee, the formation is thicker andthe uranium content lower.
So long as normal quantities of uranium were beingbrought to the sea, differences in the uranium content
of the shale would indicate differences in chemical
condition of the sea water, rate of deposition of clastic
minerals, length of time individual plant particles were
exposed to the sea water, and, to some extent, proximity
to the supply of uranium reaching the sea.
A calculation was made by W. W. Rubey (oral communication) of the hypothetical rate of accumulationof uranium in a sea like the one we envision. He called
attention to the statement by Koczy (1954, p. 126) that
present-day streams are carrying to the ocean about
1 microgram of uranium per liter of water. Combining
this estimate with that by Langbein and others (1949,
p. 4) of the total present annual runoff from all the continents, it appears that about 40,000 tons of uranium arecarried to the ocean each year. If this were precipitated uniformly over the present-day sea bottom, 1015xlO~9 gram of uranium would be precipitated in eachsquare centimeter per year. If this same rate of precipitation existed during the 5 million years that the
Chattanooga sea is assumed to have covered the area, it
would account, after allowing for radioactive decay, foran average uranium content of the entire Chattanooga
5 After this manuscript was prepared, Kinney and others (1958,
p. 24) expressed somewhat different opinions, based on studies of theorganic content of the shale. They concluded "*** these results seemto indicate, in accord with autoradiographic and other investigations,that the U is deposited more or less evenly throughout the shale constituents. *** and finally it appears that, although the U is probably
deposited in the shale because of the presence of organic matter, it
is not associated with either the mineral matter or the organic
matter exclusively, because neither the ash content nor the carbon
content *** bears any relationship to 'the percentage of uranium."

shale of 0.002 to 0.003 percent. These figures are very
close to the actual average uranium content of theseveral units of the Chattanooga shale (table 11).
It must be realized, as Rubey pointed out, thatvarious modifications could be made in the assumed
rate and conditions of deposition, some of which would
increase and others of which would decrease the amountof uranium expectable in the shale. The significant
feature of these calculations is that they yield figureson the same order of magnitude as the amount of
uranium in the shale, not figures that are 10 or 100
times greater, or only 1/10 or 1/100 as great. This
being true, there appears to be no need to seek abnormalmeans to explain the introduction of the uranium into
the shale, such as subsequent ground-water action or
igneous emanations.
REGIONAL VARIATIONS IN CONTENT

The large volume of available data has establishedbeyond reasonable doubt fairly definite regional trends
in the uranium content of the Gassaway member ofthe shale. The uranium content of the Dowelltown
member is so consistently low that no regional studies
of its trends were made. Table 11 shows the averagesof the Gassaway and the Dowelltown on the Eastern
Highland Rim of Tennessee between DeKalb andCoffee Counties.
Detailed study of the assays of the Eastern Rim
samples shows no large variation in the uranium content of the Gassaway member within a distance of 50
miles, and many of the small variations are explainable
by the local differences in thickness of the individual
units, (figs. 9, 10.) In fact, of the 36 closely spaced
cores in the Smithville area (referred to as the Youngs
Bend drilling area) only four cores had an average
uranium content that differed from the 0.006 percent
average by as much as 0.0005 percent. The chief trend
apparent from the Eastern Highland Rim area coresis a slight increase in thickness of the Gassaway
member in the easternmost holes (pis. 115, 12) and aslightly higher average uranium content for this member in that direction (table 12).
TABLE 12. Thickness and uranium content of samples of the
Gassaway member from the more eastern drill holes comparedwith the average from holes on the Eastern Highland Rim
Locality (pi. 1; table 13)3738,42.-.....-.-.
46
_
_

..
.

.

..
_ ...

Thickness(feet)

Urnaium(percent)

17.4
16.2
18.4
16.4
14.5

0.0064
.0060
.0062
.0066
.0060

South of Coffee County the lower units of the Gassaway member, as well as those of the Dowelltown, are

76

CHATTANOOGA SHALE, RELATED BOCKS, CENTRAL TENNESSEE AND NEARBY AREAS

absent, and only about 5 or 6 feet of the upper unit,
representing that part that does not contain phosphate
nodules, is present. Scattered samples indicate that inthis southern area also the unit has a fairly highuranium content but is too thin to be of economic
interest.
North from Smithville the uranium content decreases
gradually in two respects: First, the beds of black shale
having scattered phosphate nodules appear at the topof the upper unit of the Gassaway and their uranium
content is commonly only about 0.004 percent; second,
the remaining part of the Gassaway, even with thephosphatic beds excluded, tends to have a slightly
lower uranium content. This trend continues fairly
steadily into southern Kentucky as far as the shale is
exposed. Still farther north, where the shale crops
out around the Lexington Basin, its uranium content
is even lower, about 0.003 percent. This northward
decrease in uranium content probably results from thegreater thickness of the shale in that direction, presumably an illustration of the principle that more rapid
deposition is accompanied by a lower uranium content.
On the northern rim of the Nashville Basin theuranium content is lower at most places than in the
DeKalb-Coffee County area, though some cores of the
Gassaway member from northern Davidson County
and western Sumner County have uranium contents of
0.0055 to 0.006 percent. As the richer beds are only
about 10 feet thick, the reason for the low uranium
content is not clear. Perhaps, as has been postulated,
it is because much of the uranium was abstracted fromthe sea water by the bottom mud before it had a chance
to get this far from its eastern source.
Outcrop samples and four cores from the Sequatchie
anticline of eastern Tennessee show higher uranium
contents than others. These indicate that the entire
Gassaway member, which is here 11 to 21 feet thick,has a uranium content ranging from about 0.006 percent to about 0.007 percent. In the same cores, the mosturaniferous 10 to 15 feet consistently contains 0.007 to
0.008 percent uranium. The data are much too scant
and the beds are too disturbed by folding and possible
faulting to permit generalizations on average thickness
and uranium content. A plausible explanation for thehigher uranium content here is that the indicated trend
on the Eastern Highland Rim of a slight eastward
enrichening has continued under the Cumberland
Plateau where the shale is too deep for easy sampling.
It may well be that organic matter in the eastern partof the sea had the first chance to acquire uranium thatwas being contributed from the southern Appalachianarea.
The uranium content of the shale in Alabama andGeorgia is somewhat lower (Glover, 1959, p. 149-153)
than that in the Eastern Highland Rim and Sequatchie
Valley areas of Tennessee, but again, data are too
scant and the thicknesses of the shale too irregular topermit reliable generalizations as to the probablereason.
TONNAGE

The black shale of the Gassaway member weighs
about 145 pounds per cubic foot, which is equivalent
to a specific gravity of about 2.3; from this fact andfrom the uranium analyses it is calculated that shale
1 foot thick having 0.006 percent uranium contains
about 120 tons of metallic uranium per square mile.
Where the Gassaway has an average thickness of 15
feet, the uranium content is about 1,800 tons per square
mile. On the basis of the 1953 drilling, Kehn (1955,
p. 26-27) calculated that in the Youngs Bend drillingarea the Gassaway member in 21.3 square miles contains about 38,000 tons of uranium. The 500 square
miles along the Eastern Highland Rim, where drill
cores have shown that shale of similar thickness andgrade extends at least 10 miles eastward from the edgeof the basin, probably contains about 900,000 tons ofuranium. Although this tonnage must be classed as
inferred, because of the 10 to 15 mile spacing of data,
the known uniformity of the shale over large areas
permits these estimates to be made with considerable
confidence. In nearly all this area the shale is within
200 feet of the surface.
As 3 of the core holes, field localities YB-46, YB-50,
and LC-113A (fig. 16), and numerous oil test wells
have consistently penetrated the shale in areas farther
east, it seems likely that the shale is present almost
everywhere between the Eastern Highland Rim andthe belt of the folded Appalachians. Available information from widely scattered places, fortified bygeologic evidence, indicates that in this area of about
2,500 square miles a comparable thickness of blackshale of the Gassaway member contains at least 0.006
percent uranium. If the average thickness of the shaleis 15 feet, the total uranium tonnage would be about
4.5 millions tons. In about a third of this area, along
the Highland Rim, the overburden is about 200 feet or
less, but in most of the remainder it is more than 1,000
feet.
These estimates of metallic uranium in the area
where the thickness and grade of the shale are mostfavorable indicate that the Chattanooga shale of east
central Tennessee constitutes an enormous reserve if
the time ever comes when material of that grade must
be exploited. The calculations do not allow for thelosses in mining and processing the shale.

77

LOCALITY REGISTERTABLE 13. Localities 'of outcrops shown on maps accompanying
this report Continued

LOCALITY REGISTER

Brief descriptions of the outcrops visited in thisstudy and shown on the maps accompanying thisreport are given in. table 13. Field numbers wereoriginally assigned to localities of samples of the Chattanooga shale that have been studied and reported onby the U.S. Geological Survey and by several otherorganizations, including Battelle Memorial Institute,Pennsylvania State University, and the University ofTennessee; simplified numbers were assigned to the
localities for this and Hass' (1956) reports. The
system used in assigning the original numbers is explained on p. 6. Table 14, a correlation of the original
field numbers with those used in this report, follows
the locality register.
TABLE 13. Localities of outcrops shown on maps accompanying
this report[Distances are airline except where measurements along roads are specified]
Locality No.
This report andHass(1956)

Field

1.. ____ 17P-11

County, State

Description

Adair, Ky. ___ .. 11.5 miles northeast of courthouse atColumbia; from main intersection at
Knifiey, south 0.5 mile on Kentucky
Route 76; southeast bank of Casey
Creek just north of bridge.
2 _____ 17P-8..... do...... .... About 4 miles west of Dunnville on
Kentucky Route 76; cut on northside of highway and in stream bed
on south side of road.
3
17Q-129.4 miles south-southeast of courthouseat Liberty; from intersection nearschool in Windsor, about 1 mile easton Kentucky Route 80, then northon Sloans Fork road 5.2 miles to
Evona; on north bank of Sloans Fork
several hundred feet northeast of
Evona intersection.
4.-. __ - 17R-6 ... Pulaski, Ky___.
7.5 miles northwest of courthouse atSomerset; at Hogue on east bank ofFishing Creek; cut on north side ofroad.
5 __ - 17R-7 ..do ..... ..... 2.1 miles northwest f*f Oil Center Post
Office on Liberty road along PointerCreek; cut on northeast side of road.
6_
17R-9. .... _. do.... . About 5 miles west-northwest of courthouse at Somerset; road cut andstream bank at Oil Center roadbridge over Big Clifty Creek.
7-..
16Q-5- .
-do.... . ... .. 0.7 mile due east of corner of Russell,
Wayne, and Pulaski Counties and3.4 miles southwest of Norfleet;first gully north of road on east bankof Forbush Creek.
8.. ...... . 17Q-4- - Russell, Ky.. _ ._ About 8 miles east-northeast of courthouse at Jamestown; from intersection at Jabez, 2.3 miles northwest to
Wolf Creek School; on south bank of
Wolf Creek, 0.3 mile west of Wolf
Creek school, just south of mouth of
Alligator Creek; now below level of
Wolf Creek Reservoir.
916Q-3. ....
8.8 miles northeast of courthouse atMonticello; at mouth of Harmon
Creek on Cumberland River; now
below water level of Wolf Creek
Reservoir.
10........ 16P-2- . Russell, Ky ....... On bluff on east bank of Beaver Creek,
about 900 ft south of former Dowell
Ford, in shallow gully; now underwater.
11.... .... 16P-10 _ . ..... do...... ... ... . 1.5 miles south-southeast of Rowena;
cut on east side of old Kentucky
Route 35 south of Cumberland River.
12.... .... 16P-1
do
9.5 miles southwest of courthouse atJamestown; cut for the west end of
Wolf Creek Dam; now concealed bydam.

Locality No.
This report andHass(1956)

Field

County, State

Description

16N-11... _ Cumberland, Ky.. Half a mile west of courthouse at
Burkesville, Kentucky Route 90;
road cut.
1.25
miles west of courthouse at Burkes16N-1
...
-do.
...
...
14
ville, on Kentucky Highway 90; roadcut.
do....
... 100 yards south of the west approach to
14A
Cumberland River bridge; near topof broad hillside scraped for road fill.
9.5
miles south of courthouse at Edmon16H-1. 15ton; from bridge at Willow Shade, 1.4
miles west of Kentucky Route 90
along Marrowbone Creek; cut onnorth side of road.
15N-12 Clay, Tenn ....... About 3 miles east of courthouse at
16
Celina and about 250 yards west ofnorth end of Dale Hollow Dam; cut
on north side of road.
14N-4 . Overton, Tenn __ In northwestern Overton County;
17
about 2 miles south-southwest of
Timothy; west end of dam on Mill
Creek in Standingstone State Park(similar outcrop at east end of dam).
14
miles northeast of courthouse at
Clay,
Tenn
....
18
14M-10Gainesboro on Tennessee Route 53,
and 1.8 miles northeast of Clay-Jackson County line; cut on west side of
highway.
14M-13.... Jackson, Tenn.... 0.5 mile northwest of Whitleyville on
19
Tennessee Route 56, then north 1.3
miles on Lick Creek road and northeast 2.3 miles on Keeling Branch roadcut on northwest side of road.
1.5 miles north of Haydenburg school;
14L-7 ..... do..... ....
20
road cut between hairpin turns whereroad descends to Skaggs Branch.
2.9 miles southwest on Tennessee Route14L-1 2180 from its junction with Route 56,
which is 1.4 miles west of Willetteand 0.5 mile from Smith County line;
cut on northwest side of highway.
From intersection at Willette, 1.2 miles
22..-- _ 14L-5 .....doeast on Tennessee Route 56, thensoutheast 0.6 mile and 0.4 mile southsouthwest; 0.4 mile south-southwestof Fairview School; road cut.
Jackson, Tenn.... 1 mile southwest of Haydenburg school,
14L-623
on road leading to East Fork of Wartrace Creek.
0.5 mile north of main east-west ridge
24.. ___ . 14M-39-. ..... do.. ...
road at Haydenburg, on road leading
to Hunting Creek.
About 5 miles northwest of Gainesboro;
25 ____ .. 14M-6 - __ .do.
cut along Tennessee Route 85 at crestof ridge between Bullard and Cub
Creeks.
14M-7 - _____ do.
3.5 miles northeast of courthouse at
26
Gainesboro on Tennessee Route 85
and 0.6 mile east of junction with
Tennessee Route 53; cut on south sideof highway 0.2 mile west of Columbus
school.
About 6 miles northeast of Gainesboro,
14M-16 . .... .do...
27
and about 1 mile south of Pleasant
Hill school on road leading to Sugar
Creek.
14M-40 - __ do...-.
5.7 miles east of Gainesboro, on Barlow
28
Hollow road about 2 miles south ofGreenwood school and 0.6 mile northof Roaring River; cut on east side ofroad.
14M-9--- ..... do-. 6 miles east of courthouse at Gaines29.
boro, near top of steep slope overlooking Roaring River from south andabout 1 mile east of Blackman Fork;road cut.
... - About 8 miles east of Gainesboro and30- - 14M-25... ..... do...
1.2 miles southeast of mouth of Spring
Creek, at hairpin turn on roaddescending steep west slope of valley;road cut.
31.
.... 14N-3- Overton, Tenn .... 9.8 miles southwest of courthouse at
Livingston, near Overton-Putnam
County line; on east side of Spring
Creek at falls.
14M-26... Jackson, Tenn. ... 7 miles east-southeast of Gainesboro,
32about 3 airline miles south of mouthof Blackman Fork and 0.5 mile eastof stream; on road ascending steep
east wall; road cut.
13

78

CHATTANOOGA SHALE, RELATED ROCKS,TABLE 13. Localities of outcrops shown on maps accompanying
this report Continued

Field

TABLE 13. Localities of outcrops shown on maps accompanying
this report Continued
Locality No.

Locality No.
This report andHass(1956)CENTRAL TENNESSEE AND NEARBY AREAS

County, State

Description

33-

14M-27.- Jackson, Tenn. ... 0.8 mile southwest of locality 31 and51

14M-20 . .....do ......

1.8 miles northwest of church at Zion
Hill on road leading to Blackman
Fork; cut at sharp turn in road.
04
14M-14 ...
do
6.5 miles southeast of courthouse at
Gainesboro on road leading east into
valley of Blackman Fork from
Freewill school on Seven Knobs
Ridge; cut on north side of road.
35.
14M-23-- ..... do.. ...... About 8 miles south of courthouse at
Gainesboro, 1.4 airline miles southby east of locality 33 and 1.5 airline
miles north by west of Pine Hill
school on road leading to Blackman
Fork; road cut on south wall ofBlackman Fork Valley.
do
36........ 14M-35 ...
4.5 miles east-southeast of courthouse
at Gainesboro, 2.3 airline miles southof Roaring River, and 0.6 mile eastof Morrison Creek along road ascending steep slope.
14M-36... .... -do.
37About 3 miles southeast of courthouse
at Gainesboro on Tennessee Route56, then 0.5 mile east to Dudley Hill
School and 0.6 mile east on poor roadthat leads to Talley Creek; road cut
between two hairpin turns.
14M-37-About 3 miles southeast of courthouse38
doat Gainesboro on Tennessee Route56, then 0.5 mile east to Dudley Hill
school and 0.5 mile northeast on roadleading to Aaron Branch; road cut.
14M-8-... .....do..
... 1.7 miles southeast of courthouse at
39
Gainesboro on Tennessee Route 56;
cut on southwest side of highway.
14M-31 ... .....do40... 0.8 mile west of courthouse at Gainesboro on Tennessee Route 85 and 0.2
mile north of junction with Tennessee
Route 53; cut on southwest side of
highway.
41. ....... 14M-24 ... ..... do.
... - 1.5 miles west of courthouse at Gainesboro on Tennessee Route 53; highway cut on west side of hill.
14M-4442do
From courthouse at Gainesboro, 0.3
mile south on Tennessee Route 56,
then west and southwest 2.2 miles on
Gibson Hollow road; cut on east sideof road.
43 ........ 14M-15 ..... do .2.5 miles south of courthouse at Gainesboro, 2.2 miles up Shaker ag Hollow
road from its intersection with
Tennessee Route 53, and 0.8 mile
northwest of New Salem School; cut
on north side of road.
44 ___ ... 14M-21 _ .....do ...
4.5 miles south-southeast of courthouse
at Gainesboro and 1.7 miles southeastof Tennessee Route 56 on road to
Freewill school; cut on west slope of
Morrison Creek valley.
45 __ . ... 14M-22 ...
..doAbout 5 miles southeast of courthouse
at Gainesboro and 2.7 miles southeastof Tennessee Route 56 on road to
Freewill school; road cut on east slopeof Morrison Creek valley.
46- . 14M-32 ...
About 5 miles south of Gainesboro on
do .
road from Antioch school up Cub
Hollow; long outcrop near east edgeof Flynn Creek cryptoexplosive area.
47-. ... 14M-29 ... _ ..do... ... 5.5 miles south of Gainesboro, in bed of
Flynn Creek a few hundred feet
upstream from mouth of Rush Fork;boulders blasted from trench for Oak
Ridge gas pipeline.
14M-43- ... -do... .... .
48
5.5 miles south of Gainesboro; on Rush
Fork 0.2 mile south of its confluencewith Flynn Creek; on hillside down
to creek bed to west of barn.
49. 14M-38-- _ ..do.. ... ..... Long outcrop in small south-flowing
tributary of Flynn Creek, in northwest quadrant of the Flynn Creek
cryptoexplosive area; base of outcrop
is in stream bed 0.2 mile north of road.
14M-11 . ... ..do . ......
50.
7.5 miles southwest of courthouse at
Gainesboro on Tennessee Route 53;
highway cut on north side of Bell8.3 miles southwest of courthouse at
Gainesboro on Tennessee Route 53;
highway cut on south side of Bell

This report andHass(1956)

Field

County, State

Description

Jackson, Tenn .... 8.5 miles southwest of courthouse at
Gainesboro on Tennessee Route 53,
then 0.5 mile east on road to Nameless; cut on east side of road.
... 7 miles south by west of courthouse at
53 ...... 14M-33 .... .do.
Gainesboro, on road from Shady
Grove School into head of Dry Creek;
cut on side of road.
do .... ... 6.5 miles south by east of courthouse at54
14M-2
Gainesboro, on road leading northwest from Tennessee Route 56 into
Flynn Creek; roadcut 1.2 miles northwest of intersection with Tennessee
Route 56 at south edge of Gainesboro
quadrangle.
55 ...... 13M-33 - .... .do .... . 7.5 miles south of courthouse at Gainesboro; 1.4 miles west of Tennessee
Route 56 on Shepardsville road, then
1.4 miles north on road that enters
Flynn Creek road 1.5 miles east of
Antioch School; cut on side of road.
8.7
miles south-southwest of court13M-35 .
56
dohouse at Gainesboro; 7.5 miles west
on Shepardsville road to a point 0.5
mile south of Nameless, then 0.8 mileon road to a tributary of Martin
Creek; road cut.
7.6
miles south of courthouse at Gaines13M-34
do.
... ...
57.
boro, then 4.5 miles west of Tennessee
Route 56 on Shepardsville road to anintersection 0.5 mile north of Philadelphia School, and 0.2 mile north onroad into headwaters of a creek; cut
on northwest side of road just beyonda sharp turn.
58- ..... 13M-23 Putnam, Term.... From junction of U.S. Highway 70N
at Double Springs, northwest about
2 miles on Tennessee Route 56 toBloomington Springs, then northwest 1.5 miles and 1.6 miles northnorthwest on road to Goose Creek;
cut along road.
59... ...... 13M-24 . . __ do ........ About 12 miles west of courthouse at
Cookeville; cut on road 0.5 mile
north of U.S. Highway 70N; 0.25
mile east of Lafayette school.
13L-22..- Smith, Tenn ...... From west city limit of Chestnut
60
Mound, 0.8 mile northwest on U.S.
Highway 70N from intersection with
Tennessee Route 53; cut on northwest side of highway.
61
13L-8-do ... .... In eastern prong of Smith County; 3.5
miles southeast of U.S. Highway
70N at Chestnut Mound, then 0.1
mile south on Buffalo Valley road;cut along road.
About 14 miles west of courthouse at
13L-17.-- ... ..do62
Cookeville; from school at Gentry,
east on U.S. Highway 70N 0.5 mile,then south-southwest 1.8 miles onroad to Big Indian Creek; cut along
road.
..do
...
From intersection with Tennessee
13M-19 .
63
Route 56 at Boma, 1.9 miles northwest; cut on south side of road and in
stream bed.
13M-7 Gentrys Bluff, about 2 miles east of64.doBoma and 2.3 miles south of Baxter;in bed and walls of Mine Lick Creek.
Fromintersection on Tennessee Route65..
13M-10 .
.do
56 at Silver Point, northeast 1.4 miles
on Tennessee Route 56, then southeast 2.5 miles across Mine Lick Creek;
cut along road.
13L-11..- .....do ..... .. From Silver Point, 2.5 miles west on
66
road to Center Hill Dam; cut alongroad.
13L-13-... DeKalb, Tenn __ About 4 airline miles northeast of67
Dowelltown; roadcut on west side ofDale Ridge near headwaters of Reynolds Branch.
About 11 miles northeast of courthouse
13M-32.do.
68..
at Sinithville on Tennessee Route 56;
cuts along highway on crest of ridge
about 2 miles north from west end of
Hurricane Creek bridge over Center
Hill Reservoir.
About 10 miles northeast of courthouse
13M-31..do.
69
at Smithville on Tennessee Route 56
and 1.2 miles north from west end of
Hurricane Creek bridge over Center
Hill Reservoir; cut for highway.
52. ..... 14M-30-

79

LOCALITY REGISTERTABLE 13. Localities of outcrops shown on maps accompanying
this report Continued

TABLE 13. Localities of outcrops shown on maps accompanying
this report Continued
Locality No.

Locality No.
This report andHass(1966)
70. _ -

Field

County, State

Description

13M-30 - DeKalb, Tenn.... About 7 miles northeast of courthouse

at Smithville on Tennessee Route 66;
highway cut along south approachto Hurricane Creek bridge.
do.....
- 0.5 mile north of Buckner school on
71.... - 13L-20.
old Tennessee Route 56; cut alongroad.
13M-5 - . ..do. ... ...
About 7 miles northeast of courthouse72.
at Smithville and about 2 airline
miles north of Laurel school; cut
along road.
13M-1 Putnam, Term..-. At Burgess Falls, about 10 miles south73.
southwest of courthouse at Cookeville; 0.1 mile upstream from old
Cookeville power plant on Falling
Water River.
13M-4 White Tenn ... About 10 miles northwest of Sparta;
74 __1.7 miles east of Peeled Chestnut on
Tennessee Route 26, then 2.6 miles
north; at Taylor Creek Falls.
LC-4 ... DeKalb, Tenn. ... 0.5 mile northwest of Tennessee route 26
75
at point where it begins its descent toeast end of Sligo Bridge, along nowabandoned private road; road cut.
..doLC-55 ....
About 7 miles east of courthouse at
76
Smithville on Tennessee Route 26
and 0.3 mile northeast from the eastend of Sligo bridge over Center Hill
Reservoir; deep highway cut.
Core hole, 0.7 mile southwest along
LC-102. ... -do ....
77
old Tennessee Route 26 from point
where it joins present Route 26, at
top of descent to east end of Sligo
bridge (old highway abandoned in1948 but now used as boat-landingroad); about 100 feet west and 30 feetabove road, on crest of narrow ridge.
... About 1 mile southwest on old Ten78
LC-10 - ..... do..
nessee Route 26 (now a boat-landingroad) from point where it joinspresent Route 26 at top of descent toeast end of Sligo bridge.
79 __ LC-201 -do- Adit, about 140 feet northwest of locality 78.
80.
LC-2.....do0.5 mile west of Sligo bridge overCenter Hill Reservoir; cut along
long-abandoned highway on northwest side of Short Creek.
LC-1 - ... ..do.
81
About 6 miles east of courthouse at
Smithville; cut along old Tennessee
Route 26, 0.5 mile southwest of Sligo
bridge over Center Hill Reservoir.
Road abandoned in 1948 and exposure now covered by debris fromnew highway above.
LC-56 ~ ..... do ... ... ... - About 6 miles east of courthouse at
82
Smithville on new Tennessee Route
26; deep cut along west approach to
new Sligo bridge over Center Hill
Reservoir, 0.6 mile from west end ofbridge.
LC-50 - ..do ..... .... 2.25 miles south of Sligo bridge over83
Center Hill Reservoir and 1.5 miles
northeast of Youngs Bend school;
west-facing waterfall in branch of
Short Creek.
84
LC-6..do 8.7 miles southeast of courthouse at
Smithville and 0.3 mile east of Taylor Branch; waterfall on small
stream a few hundred feet north ofCenter Hill Reservoir.
85- . LC-51.-- White, Tenn-. .... 9.5 miles west of Sparta; bluff at site ofold mill at junction of Cedar Creek
and Water Falls branch.
QA
LC-8.DeKalb, Tenn _ . 9.5 miles southeast of courthouse at
Smithville; bed of south-flowing tributary of Sink Creek at west edge ofCenter Hill Reservoir.
JW
LC-33---.
do ... ... ... 2.4 miles east-northeast of Keltonburg;
bluffs on Sink Creek.
fift
LC-11White, Tenn.. .... In southwestern White County. 4.8
miles west-northwest of Walling;south bank at northernmost part ofHorseshoe Bend of Caney Fork; now
below water level of Center Hill
Reservoir.
QQ
LC-30- ... DeKalb, Tenn.... 4.3 miles southeast of courthouse at
Smithville and 2.7 airline miles westof Center Hill Reservoir; main waterfall on Pine Creek.

This report andHass(1956)
on

Field

County, State

Description

LC-12--.. DeKalb, Tenn .... 2.5 miles east-southeast of courthouse

at Smithville; at small waterfall onsouth side of gorge 900 ft. downstream
from main falls of Fall Creek.
. do
About 1 mile north of Tennessee RouteLC-17
91
26 at Pomeroy Chapel, which is 3.4
miles east of Smithville; cut alongroad.
00
1.6 miles north of courthouse at SmithLC-15 ....do...
ville on Holmes Creek road; cut alongroad.
LC-103 . .. do .... ... Core hole. 3.8 miles south of courthouse
93 __at Smithville, on west side of Tennessee Route 56.
LC-105A-. ....do..... ....... Core hole, 5 miles south of courthouse94
at Smithville on Tennessee Route 56,
then 1 .5 miles east, and 0.8 mile south;
just north of road fork.
LC-34..... ... .do.. ........ Snows Hill; 3.1 miles southeast of Dow95 __elltown, and 6.5 miles west of Smithville courthouse, an old Tennessee
Route 26; cut on south side of road.
A much better exposure is now available in a deep cut along the relocatedhighway north of the old one, about
6 miles west of Smithville.
R-C8-..- .... do....
About 3 miles west of courthouse at
96.
Smithville and 5.5 miles southeast of
Dowelltown; at Egypt Falls on tributary of Dry Creek.
07
R-C5- . .....do... ......... About 8 miles west-southwest of courthouse at Smithville and about 2 miles
east of Gassaway; cut on north side ofgravel road to Mt. Moriah school.
R-C7. - .....do.
About 8 miles southwest of courthouse98
at Smithville, about 5 miles southeastof Gassaway and 1.8 miles north of
Cripps' store near Cannon County
line; at English Falls near head of
Dry Creek.
RC-4-. Cannon, Tenn .... 6.5 miles east-northeast of courthouse at
99Woodbury; from courthouse, 0.7 mile.east on U.S. Highway 70S, then northand east on Stone River road 6.8
miles; 0.7 mile west of intersection
with Short Mountain road; south sideof road, near a waterfall in Stone
River.
inn
do..... ..... .. South from Gassaway 5.0 and 5.4 miles
LC-60....
on Tennessee Route 53; cuts on northand south sides, respectively, of ridge.
R-C63.6 miles north on Auburntown roaddo... ...
101from its junction with U.S. Highway
70S on west edge of Woodbury; cut
on west side of road.
102. - R-Cl - .....do... ... ... 2.5 miles south of courthouse at Woodbury along Tennessee Route 53; cut
for highway.
..do...... ... About 4 miles south of courthouse at103- ... R-C2.
Woodbury and 1.4 miles west of
Tennessee Route 53 at Sheboygan;
cut along road.
104....... R-C3- . _ .do~ 3.7 miles northwest of Hollow Springs
crossroads and 2.9 miles south of thechurch at Brady ville; cut on west sideof road.
105 ....... 11J-1.
Bedford, Tenn ... About 5 miles northeast of Bell Buckle;
from main intersection in Bell Buckle
east for 4.8 miles, then north 1.7 miles
and continue north by walking about
1 mile to head of the east fork of
Puncheon Camp Creek; poor outcrop
in saddle just south of county line.
Coffee, Tenn ..... 3.3 miles northeast of U.S. Highway 41,
106 ...... UK-2
on McBride Branch road; 0.2 milesouthwest of Wilsons Chapel schoolat Hoodoo; cut along road.
UK-1. ..... do.. ..... About 10 miles northwest of Man107
chester, and 1 mile northwest of
Noah on U.S. Highway 41; deep
highway cut.
..do....
. About 7 miles northwest of Man108 ... UK-16
chester, and 2 miles southeast of
Noah on U.S. Highway 41; cut onsouthwest side of road.
11.3 miles east-northeast of courthouse
Bedford, Tenn
11J-6
109
at Shelbyville and 1 mile west of
crossroads at Shiloh cemetery; cut
along road.

80

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

TABLE 13. Localities of outcrops shown on maps accompanying
this report Continued

TABLE 13. Localities of outcrops shown on maps accompanying
this report Continuedv
Locality No.

Locality No.
This report andHass(1956)

Field

10K-6 __ .

County, State

Description

8.5 miles west of courthouse at Manchester; 0.3 mile south of church at
Holland Hill; cut along road.
....... 2.8 miles west of courthouse at Man10K-3 - - ... ..doIllchester and 0.9 mile east of Blanton,
immediately west of Haggard Creek
ford; cut along road and in small
creek.
11210K-4_do
5.3 miles southwest of courthouse at
Manchester and 1.6 miles west of
Mountview school on road leading toCrumpton Branch; cut along road.
10K-5 do .......... About 4 miles north-northwest of Tul113
lahoma and 2.5 miles west-northwestof Ovoca; cut along Cascade Branchroad.
10J-8 . Moore, Tenn _ ... Northeastern panhandle of Moore
114
County; 2.8 miles northeast of junction of Tennessee Routes 16 and 55;
cut on northeast side of road below
Ledfords Mill dam.
115
10J-4 __ ..
.do...
Northeastern panhandle of Moore
County; 0.5 mile northwest of intersection of Tennessee Routes 16 and 55
along road to Ledfords Mill; hi stream
bed 0.2 mile west of road.
10J-3. __ do- Northeastern Moore County; 0.5 mile116
on Tennessee Route 16 northwestof intersection with Route 55; scattered outcrops for several hundred
feet along stream bed of Bennett
Hollow, on southwest side of road(rocks folded and faulted (?) at irregular angles).
10J-2 ......
do... ..... .... . 5.5 miles north-northeast of courthouse117
at Lynchburg along Tennessee Route55; poor outcrops on both sides ofhighway.
10J-9 __ .. - do
118
About 6 miles northeast of courthouseat Lynchburg; along Hurricane
Creek just below dam at Cumberland
Springs.
10H-40 Bedford, Tenn .._. About 16 miles north of the courthouse
119
at Fayetteville along U.S. Highway
241; cut on east side of highway.
10H-39 . Lincoln, Tenn. __. 11 .5 miles north of courthouse at Fayetteville on U. S. Highway 241; cuton east side of highway.
10K-10 Franklin, Tenn... 1.2 miles east of Await; hi cut along121
north-south road.
199
10K-11.do
About 1 mile southwest of Estill
Springs and 0.4 mile northeast ofRock Creek bridge; hi river bluff at
point where river is closest to road.
9J-51
do ....
123
8.7 miles west of courthouse at Winchester and 0.5 mile west of Harmonyon Tennessee Route 50; cut on westside of curve.
Lincoln, Term. ... 13.8 miles east of courthouse at Fay124
etteville on U.S. Highway 64, thennorth 0.4 mile; in bank of Shelton
Creek about 500 ft south of the southpool of fish hatchery, hi picnic area.
.....do....... ...... 3 miles southeast of Kelso on U.S.
125- - _9J-50
Highway 64; cuts on both sides ofhighway just south of sharp turn.
... ..do- ..... ... About 4 miles south of courthouse at
126- ___ 9H-11
Fayetteville on U.S. Highway 241;
cut on east side of highway, andgully below highway and 100 feetwest of it.
8J-1. ._
127.
At Quicks Mill on Flint River, about
12 airline miles north-northeast of
Hunts ville.
9H-48
Lincoln, Tenn .... 0.7 mile east of main intersection at
128
Taft along Tennessee Route 110,then 0.8 mile north and northeast
0.15 mile; cut in gully on southeast
side of road.
129 ___ . 9G-47 - Giles, Tenn....... 1.5 miles northwest along U.S. Highway 31 from Louisville & Nashville
RR. overpass at Tennessee-Alabama
State line hi Ardmore; in gully oneast side of road at north end of roadcut.
... .. About 8 miles east of Pulaski on U.S.
130 ....... 9G-43- - .... .do....
Highway 64 and 2.5 miles west ofLouisville & Nashville RR. overpass
at Frankewing; cut on south side of
highway.
110

This report andHass(1956)

Field

131..

10G-41

132..

10H-38133 - _ . 10G-37

Description

County, State

Marshall, Term...

do

134

10G-36 -135

10G-34...

136 _10F-44137- 9G-42

138 _

9F-45

..... do

139 _9F-86-

do

140 -9F-85- .... - do

141 .

8F-12-

Limestone, Ala

142

8F-11

... ..do

143

8E-89-

Lauderdale, Ala ...

144

8E-88 .....

145 _ - ... 8D-90

146 _- 8D-66

do

_. .

.. do

.....

do...

...

........

do... ..do-do147-. .. ... 9D-66 - Lawrence, Term...
148

9D-84

149 .... 9D-82.....do... .........

do-

-.-

From courthouse in Pulaski, north 0.5
mile on U.S. Highway 31 and east for
7.9 miles on U.S. Highway 31A; cut
on northwest side of highway.
From courthouse at Lewisburg, southsoutheast 0.4 mile, then south 5.1
miles on black-top road along Thompson Creek; on south side of road justeast of intersection near top of hill.
From junction with U.S. Highway 31 A
at Cornersville, 2.4 miles west-northwest along Tennessee Route 129, then
0.1 mile north, 0.7 mile north-northwest, and 0.2 mile along lane; onsoutheast side of lane.
From junction of U.S. Highway 31A
and Tennessee Route 129 at Cornersville, west for 0.9 mile; cut on south
side of highway.
1.7 miles east of Louisville & Nashville RR. crossing hi Lynnville on
Tennessee Route 12, then south 1.4
miles to farmhouse; at spring 200
yards behind house.
From intersection of U.S. Highway 31
and Tennessee Route 129 hi Waco,
south 0.2 mile, west 0.35 mile, south
2.3 miles to road fork, and north for0.25 mile; in gully on south side ofroad opposite farmhouse.
From courthouse in Pulaski, north on
U.S. Highway 31, then east 2.7 miles
on U.S. Highway 31 A; cut on northwest side of highway.
11.5 miles west of Pulaski, and 3.3 miles
west of Bodenham on U.S. Highway
64; in creek bed north of road.
From schoolhouse in Minor Hill, north
0.1 mile on Tennessee Route 11, thenwest on valley road 2.4 miles, northwest 0.9 mile, and north 0.7 mile; ingully on southwest side of road.
From schoolhouse in Minor Hill, southwest 4.3 miles on Tennessee Route 11,then west 0.6 mile; in creek bed 100
ft south of road.
About 2 miles northwest of Elkmont
and 1.6 miles southeast of Elfe Riverbridge, on Alabama Route 127; cut
on west side of highway.
From courthouse hi Athens, west on
Buck Island Road 6 miles just past
Owens school, then west 3.8 miles;
quarry on north side of road.
1 mile east of Ebenezer School at Center Hill; below east abutments ofbridge over Bluewater Creek.
From Ebenezer school at Center Hill,
west-northwest 2.5 miles, then northat Y intersection 0.1 mile and east
1.1 mile; in road ditch on south sideof road immediately after crossing
Bluewater Creek.
From schoolhouse at Green Hill, southon U.S. Highway 43 and Alabama
Route 5 0.1 mile, then west 5.1 miles
to bridge over Crystal Springs Creek(0.2 mile east of Shoal Creek bridge);east bank of creek south of bridge.
From Louisville & Nashville RR.
crossing at Blackburn, southeast 1.0
mile, then north 0.2 mile; in gully oneast and west sides of road.
From main business section in Iron
City, 1 block south, then west 0.5
mile; at spring on south side of road.
About 13 miles southwest of courthouseat Lawrenceburg about 1 mile southsoutheast of Chinubee; bluff 0.4 milesouth of bridge over Shoal Creek,
east of road and 20 ft above it.
From courthouse at Lawrenceburg,
south 8.3 miles on U.S. Highway 43,
then west 0.3 mile, north 0.2 mile,
west 0.3 mile to Springers Station,
west-northwest 3.1 miles, west 0.9
mile, north 0.7 mile, and southwest
2.0 miles; in bluff southeast side ofroad above Knob Creek.

LOCALITY REGISTERTABLE 13. Localities of outcrops shown on maps accompanying
this report Continued
Locality No.
This report andHass(1956)Field

81

TABLE 13. Localities of outcrops shown on maps accompanying
this report Continued
Locality No.

County, State

Description

150. .... 9D-83 __ . Lawrence, Tenn~ From Springers Station (see above),
5 miles west; across Shoal Creek andup Long Branch; 30 ft east of road ata mill and beneath falls of Long
Branch.
151....... 9D-1 __ . .... .do...... ...... About 9 miles west-southwest of
Lawrenceburg and 1.6 miles southwest of road intersection at Pea
Ridge; south side of road about 200 ft
west of Knob Creek.
152. .. ... 10F-65 Maury, Tenn
From main intersection in Mt. Pleasant, south 0.7 mile on Tennessee
Route 43, then where highway bends
southwest continue south on gravel
road 4.2 miles, then southwest 2.2
miles; at spring on east side and 20
feet behind house.
11F-7 .... .do...... ..... . From abandoned blast furnace on west
153.
edge of Rockdale (about 6 miles
southwest of Mt. Pleasant), 0.5 milesouth on Tennessee Routes 6 and 43;
along east bank of stream 100 ft eastof highway.
9D-82. .... ... -do -154
From Mt. Pleasant, west 1.7 miles,
then north 0.5 mile along Big Bigby
Creek and west 1.4 miles along Camp
Branch; Hardin sandstone on southeast-facing slope 300 ft west of house.
(Another exposure 0.3 mile farther
northwest on main road, 40 ft northof a house.)
156- . HE-32 . .....do ......... From Hampshire, south on Hampshire
Creek (Baptist Branch) road 3.6
miles; near Lewis County line; inwest bank of creek 15 ft north of road.
157-.
HE-33. ... Lewis, Tenn.. .... From Gordonsburg school, 3.8 miles
southeast on road along Swan Creek;in cut 10 feet above west side of road.
158-...... HE-1. .... .... . do.
... From Gordonsburg school, 1.5 miles
east on Tennessee Route 99; road cut
where highway makes sharp turn tonortheast.
159 ....... HE-2 ..... do
From Gordonsburg school, 1.9 miles
northwest on Tennessee Route 99;
cut along west side of highway 0.1
mile southeast of intersection with
Little Swan Creek road.
3.5 miles due north of Gordonsburg
160- __ - HE-3
doschool; outcrop behind farmhouse ateast end of Dry Branch road.
161- ___ . HE-69 .... Hickman, Tenn ... About 10 miles south of courthouse atCenterville, then 1.4 miles south on
Tennessee Routes 100 and 48, southeast on Tennessee Route 50 to Swan
Creek road, and south to point about
2 miles north of Lewis County line;
15 feet north of bridge over Swan
Creek, on west side of road.
162- ...... HE-5.. ... ... ..do- ... ... About 1 mile north of locality 161; cut
on west side of road.
163. __ 12D-71 . .....do .... . - 3.0 miles southwest of main intersection
at Coble on Tennessee Route 50;
highway cut.
164_ ___ . 12D-72 _ . ..... do- ... ..... 1.4 miles southwest of main intersection
at Coble on Tennessee Route 50;
cut on southeast side of highway.
165. ..... 12E-54 .... .....do ......... 1.8 miles north-northeast of courthouseat Centerville on Tennessee Routes
100 and 48; cut on west side of highway.
166 ...... 12E-67..do...... ...... 0.4 mile south of courthouse at Centerville on Tennessee Routes 100 and 48;
cut about 20 ft above east side of
highway.
167 ....... 12E-6 ..... ... ..do.... ..... 1.2 miles south of courthouse at Centerville on Tennessee Routes 100 and 48,
and 0.3 mile southeast on Route 50;
cut on northeast side of highway.
168. - __ . 12E-5. _ . ..... do......... ... 1.4 miles south of courthouse at Centerville on Tennessee Routes 100 and 48,
and 2.3 miles southeast on Route 50;
cut on southwest side of highway.
169.. .... 12E-68 ..... do....
. 1.4 miles south of courthouse at Centerville on Tennessee Routes 100 and 48,
and 4.1 miles southeast on Route 50;
cut on southwest side of highway.
170- ...... 12E-77 .... .....do .......... 0.9 mile north of Littlelot; in stream
bed 50 feet west of road.

This report andHass(1956)
171-.

Field

County, State

Description

12E-78- ... Hickman, Tenn ... West-southwest edge of Frimm; cut oneast side of road.
.... . 2.5 miles north-northeast of schoolhouseat Primm; in road bed and cut oneast side of road.
do
1.6 miles northeast of Jones Valley store,
12F-30173then east 0.7 mile; in south bank ofcreek south of road, near Maury
County line.
From intersection at Water Valley,
17411F-29west 1.1 mile; cut on north side ofroad (another exposure 0.1 mile
farther west).
175 ___ - 12E-76Hickman, Tenn... 1.5 miles northwest of Shady Grove on
Tennessee Route 60; cut on northeast
side of highway.
176 ._.. 10E-60 Maury, Tenn ..... From Duck River bridge at Williamsport, north on Tennessee Route 50
0.2 mile, then southwest 2.5 miles;
cut on west side of road.
177 __
11F-28 __ ... -do .... ..... . From bridge over Duck River at Williamsport, north 0.1 mile, then east
1.4 miles, north 0.7 mile, and west to
farmhouse; at spring about 1,000
yards west of house.
From Sante Fe Post Office, 3.7 miles
11F-91. ... ... ..do..-178.
southeast on main road, then southwest 0.1 mile; at spring behind barn
about 100 ft north of road and 40 ft
below it.
17Q
From Sante Fe Post Office, 2.6 miles
11F-26.....do ......
south-southeast on main road; cut oneast side of road.
12F-27 ... ..do.... ... From Theta, 1.5 miles west-southwest
180.
on main road; cut on northwest sideof road.
.... From Theta, 1 mile on road east181 ___ - 12G-8 ..... ..... dosoutheast; cut on south side of road.
182 ___ - 12G-23 Williamson, Tenn. 10.3 miles southwest of courthouse at
Franklin; from Y intersection at
Burwood, north 0.3 mile, then west
1.2 miles and northwest 0.25 mile;cut on northeast side of road.
..... do.... From intersection at Boston, east 0.1
12F-24183mile, then south 0.1 mile and northeast 0.35 mile; on northwest bankof stream 300 ft north of road.
12F-25 .... . do ....... ... From intersection at Boston, north 2.3
184
miles on Tennessee Route 106, thenwest on Garrison road 1.5 miles to
Garrison school, south 1.6 miles, andeast about 0.1 mile; in gully on eastbank of creek south of road.
12H-31 . ..... do.... ..... In southeastern corner of Williamson
185County; 3.0 miles east of intersection
at Bethesda and 1.2 miles east of
Cross Keys; in gully on southeast
side of road.
... ..do..... From public square in Franklin,
186southwest 4.2 miles on Carter Creek
pike, then west 0.5 mile to Johnson
Carbsil plant. Several small quarries, difficult of access by car, on
hills to north and northeast within
a 1-mile radius of plant.
12G-19. ... ..... do. ......... About 4 miles northeast of courthouse187.
in Franklin on U.S. Highway 31,
then north 1 mile on Holly TreeGap road; blufl 50 ft north of roadbehind barn.
do ....... ... 6.4 miles west-northwest of courthouse188
12G-21. ...
at Franklin; from intersection at
Forest Home southwest 3.6 miles on
Tennessee Route 106, then northwest
0.4 mile and north-northwest 1.2
miles; in west bank of Tucker branch,
50 ft west of road.
7.7 miles northwest of courthouse at
IRQ
12G-20, ... ... ..do ... ....
Franklin; from intersection at Forest
Home, 1.9 miles southwest on Tennessee Route 106, then northwest 3.5
miles; in stream bed 15 ft northof road.
13F-22. ... Davidson, Tenn. . From intersection in Linton, 0.7 mile
190 _south from Tennessee Route 100; inbluff 50 yards north of bridge over
the South Harpeth River.
19113G-55 .... .... .do ....... ... From intersection at Linton, northeast
3.3 miles on Tennessee Route 100,
then north 1.6 miles and east 0.52
mile; cut on south side of road.
172- ...... 12E-79... ..do82

CHATTANOOGA SHALE, BELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

TABLE 13. Localities of outcrops shown on maps accompanying
this report Continued
Locality No.
This report andHass(1956)Field

TABLE 13. Localities of outcrops shown on maps accompanying
this report Continued
Locality No.

County, State

Description

192 ___ - 13F-9 ... Cheatham, Tenn.. 2.2 miles west of Pegram on U.S.

Highway 70; in vertical bluff onnorth side of highway.
193 ....... 13G-7. _ . Davidson, Tenn- . From main intersection in Brentwood
north on U.S. Highway 31 for 2.3
miles, then west 1.7 miles and south
on private road 0.4 mile; on hill southof barn.
13G-11 ..... do..... 1.4 miles southwest on U.S. Highway
70S from junction with Tennessee
Route 100 at Belle Meade, then 0.4
mile on secondary road that is northof highway and parallel with it overNine Mile hill; small quarry on northside of road just east of crest of hill.
195 __ ... 13G-12 ..... do- .... ..... 5.8 miles southwest of Richland, awestern suburb of Nashville, on U.S.
Highway 70N; 2.3 miles northeastof junction with U.S. Highway 70S;
bluff on north side of highway.
do. ...
196.... 13G-81 .
On Tennessee Route 12 about 7.5 miles
west of its junction with U.S. Highway 41W, northwest of Nashville;
cut on north side of highway.
197. - 13G-80 _ . Cheatham, Tenn.. 5.8 miles southeast of courthouse at
Ashland City on Tennessee Route 12;
cut at boundary between Cheathamand Davidson Counties.
do ...
198... - 13G-3.
From intersection with Tennessee
Route 12 in Ashland City, west on
Tennessee Route 49, 0.8 mile, thensoutheast on river road about 7.8
miles; cut on south side of road.
199... _ - 13G-4..do.. ...... From intersection with Tennessee
Route 12 in Ashland City, west on
Tennessee Route 49, 0.8 mile, thensoutheast on river road 3.6 miles; cut
near intersection of roads.
200 _ .
13F-1---. ..... do ... ....
3.5 miles southeast of Ashland City on
Tennessee Route 12, then northeast
0.6 mile; about 20 ft south of bridgecrossing Marrowbone Creek.
14G-2
201..
Davidson, Tenn_. 3.5 miles southeast of Ashland City on
Tennessee Route 12, then northeast
about 1.2 miles and east across bridgefor 2.6 miles along Little Marrowbone
Creek; bluff along road.
202-.
13G-1
-do. 6.5 miles southeast of Ashland City on
Tennessee Route 12, then north along
Bull Run 2.3 miles; on nose of hill inbarnyard.
203 ....... 14G-1
doAlong Crocker Springs Branch, tributary to Whites Creek, about 11 miles
north of the State Capitol at Nashville, 1.3 miles north-northwest fromroad intersection just south of Lickton school; a stream bluff on eastside of road and an exposure along
spillway below small dam on westside of road.
14G-6. .... .do .....
203A
About 11 miles north of the State Capitol at Nashville and 1 mile west by
south of loc. 203; 1.6 miles up Claylick
Creek from road intersection along
Whites Creek; cut on northeast sideof road.
. . About 9 miles north of the State Capitol
14G-5-- ... ..do203B.
at Nashville; 1.3 miles west along
Campbell Lane from U.S. Highways
31 W and 41; cut on both sides of roadjust east of crest of hill.
204 _ .... 14G-14.do
3.7 miles north-northwest of Goodlettsville on U.S. Highway 41E, thenwest 0.7 mile to Louisville & Nashville RR. tracks at Bakers Station;
cuts about 100 ft north and 1,500ft south of crossing.
205-14J-13
Sumner, Tenn._.- 5.5 miles north of courthouse at Gallatinon Tennessee Route 109; cut on eastside of highway.
206.- - 15J-13..do .
From junction with U.S. Highway
31E in Westmoreland, south 1.8
miles on U.S. Highway 31E; stream
bed and bank on west side of highway.
20715K-2. _ .
do ... ...
In northeastern Sumner County, 4.5
miles north of Westmoreland; 200
yards north of Garretts Creek
church; west bank of creek.

This report andHass(1956)

Field

County, State

Description

From Red Boiling Springs, west-southwest on Tennessee Route 52 about 7.5
miles; cut on west side of road onwest slope of Long Fork Creek.
.do ..... ... From Red Boiling Springs, west-south15L-4209west on Tennessee Route 52, 6.4
miles; cut along north side of road oneast slope of Long Fork Creek.
210- ___ 15L-10. Clay, Tenn... .... About 3.75 miles southeast of Red Boiling Springs, Macon County, on the
Hudson Creek road, about 0.15 mile
northwest of the Clay-Jackson
County line; cut on northeast side ofroad.
211 __ . ... LC-113A- White, Term. _ .. Drill hole about 8 miles southeast of
Sparta; about 300 ft east of Dodson's
store, 50 ft east of Caney Fork and 75
ft north of road.
212--- 10M-1- . Grandy, Tenn- Core of the Magnolia Petroleum Patterson 1 at Gruetli, about 660 ft
northwest of main intersection. In
this well the Chattanooga shale is1,455 to 1,476.5 ft below the surface.
Rhea, Tenn ___ - 0.9 mile west of Roddy in northern part213- ...... 12Q-1
of county; cut and ditch along side of
road.
914
From intersection of U.S. Highway 27
and Tennessee Route 30 in Dayton,
northeast 1.8 miles on U.S. Highway
27 to Walnut Grove school, thennorthwest on county road 0.8 mile tointersection; road cut just west ofintersection.
R-S6 ... Bledsoe, Tenn _ . 2 miles east of road junction near Cedar
215
Ridge; on southwest side of road andon northeast side below the road.
About
6 miles northeast of courthouse
R-S3 ... ... -do ... .... ...
216
at Pikeville; 2.1 miles east on dirt
road from its junction with northeastsouthwest gravel road on east side of
Sequatchie River; upper part ofsection is on east side of Beatty
Creek, lower part is on northwestside of southwest fork of Beatty
Creek.
R-S16
About 2 miles east of courthouse at
do ...
217
Pikeville on Tennessee Route 30; inold chert pit about 200 ft west of
highway.
7.7 miles south-southwest of courthouse
218. - R-S14.do
at Pikeville; from bridge over Sequatchie River, about 1 mile east on
Pitt Gap road; northwest side of road.
R-S17 .... -do ... ... - 13.3 miles south-southwest of court219
house at Pikeville; from Stephen
Chapel on east side of SequatchieRiver, southwest 2.5 miles, theneast 0.7 mile; on north side of McWilliams Creek just north of road.
220 ... R-S1 ... Sequatchie, Tenn. About 5 miles south of courthouse at
Dunlap; 1 mile south of junction
with Tennessee Route 28, on Route8; highway cut.
221 ___ .. R-S2 ... Marion, Tenn. ... From junction of Tennessee Routes 27
and 108 just south of Whitwell, about
4 miles east on Tennessee Route 27
and 1.3 miles east of Powells crossroads; highway cut.
999
R-S15 .... .do ... ... ... . On U.S. Highways 41, 64, and 72,
between Jasper and the Tennessee
River, 2.5 miles west of west end ofbridge over Tennessee River; cut onnortheast side of highway.
Hamilton, Tenn.. 0.5 mile west of junction of U.S. High223 __ .... R-S19
ways 11 and 41; cut on north side ofHighway 41.
224... . 9N-2-. _ . ..... do ... ... ... . From intersection of Tennessee Routes
8 and 27 in North Chattanooga, south
0.5 mile, then northeast 0.7 mile andnorthwest 0.1 mile; cut on north sideof road, 0.5 mile from above highway
intersection.
9N-1..... do...
... . From Intersection of Tennessee Routes
2258 and 27 in North Chattanooga, west
on Route 27 about 200 ft; on hiUslope
south and about 10 ft above railroad
tracks.

208. __ . 15L-3-

83

LOCALITY REGISTERTABLE 13. Localities of outcrops shown on maps accompanying
this report Continued
Locality No.
This report andHass(1966)

Field

9N-3

Locality No.

County, State

Description

Hamilton, Tenn.. Type locality of Chattanooga shale.
On north slope of Cameron Hill in
Chattanooga. From Market Street
1 block west on West Second Street,then 1 block north on Broad Street,west 0.4 mile, and south about 200 ft;
outcrop in woods about 50 ft above
road.
227.
BR-133 .. do .......... About 1 mile east of Ooltewah; cut onnorth side of U.S. Highway 64.
228 _BE-132do.... . .. About 1 mile east of Collegedale railroad station; cut on south side ofrailroad.
229.
7N-62 .. "Wallrnr Cict
About 4 miles northwest of courthouseat Lafayette; on northwest side ofDug Gap in gully on west side of
hairpin turn.
230.
6N-53 Chattooga, Qa
West of Menlo, on Georgia Route 48;
4.4 miles east of the State line and 2.8
miles southeast of Cloudland; on
Shinbone Ridge; cut on north side of
highway.
231.
6M-1......
At Fort Payne, about 300 ft northwestof U.S. Highway 11 on Alabama
Route 35; highway cut.
232.. .. 4J-1...
From junction of Alabama Routes 25
and 38 at the northwest edge ofOneonta, 0.2 mile northwest on
Route 38: cut on west side of road.
233....... 40-1. ..... do....
At Blount Springs, 0.5 mile east of U.S.
Highway 31, on country road 0.25
mile above a hairpin turn; road cut.
234. .
On U.S. Highway 31 at Birmingham,
about 2 miles south of Third Avenue,
just south of the highway crest at
Vulcan Park; road cut.
235
8B-1...... Tishomingo, Miss. About 3 miles south of Tennessee Stateline and about 200 ft upstream frommouth of Whetstone Branch; on
north bank of stream, probably in
NEJ4 sec. 31, T. 1 S., R. 10 E.
236 _ .... 9B-87
Hardin, Tenn __ From courthouse at Savannah, 18.6
miles southeast on Tennessee Route69, then southwest 2.7 miles, south
0.6 mile, due west 5.7 miles (this roadin Alabama), north along east bankof reservoir 0.8 mile, northeast up
steep hill and east about 1 mile, andsouth by foot up ravine; on westbank of small stream 125 ft north ofwaterfall.
237
9B-1 . ..... do... ...... About 12 miles southeast of Savannah;
near edge of Lowryville, road cut 0.1
mile from Intersection on road ascending hill southwest.
238
10B-2 ..... ..... do......... . 0.2 mile east on U.S. Highway 64 from
center of Olivehill; cut on north sideof highway. (Hardin sandstone
only.)
239
10B-3 . .... -do.. ... ... . 0.15 mile south of U.S. Highway 64 in
Olivehill; ditch beside gravel roadnear a small church.
240 ....... 10B-1.. ... ..... do... ...
1.8 miles west of Olivehill on U.S.
Highway 64; cut on south side of
highway.
226-

TABLE 13. Localities of outcrops shown on maps accompanying
this report Continued

This report andHass(1956)

Field

County, State

Description

241....... 9C-1 ...... Wayne, Tenn. ... . About 8 miles southwest of Waynes-

boro and 2.5 miles northwest ofThree Churches on Indian Creek
road; cut along road for 0.2 mile.
... ... From intersection with U.S. Highway
242.
10C-1 .... .do.
64 in southwestern Waynesboro, 2.1
miles southwest on Hog Creek road;in creek bed 50 ft east of road.
0.5 mile north of courthouse at Waynes243 ...... 10C-46do
boro along Tennessee Route 13; cut
on west side of highway.
From first intersection east of Buffalo
244....... 10D-50
River at North Riverside, south
along Aliens Creek road 0.95 mile,then 0.8 mile north of abandoned
blast furnace at Ruppertown; in bluff
100 ft east and 20 ft above road, justnortheast of house.
8.5 miles north-northeast of courthouse245
10D-59 at Waynesboro and 0.5 mile north ofTopsy; cut along west side of road at
hairpin turn just south of Buffalo
River bridge.
11.5 miles north of courthouse in
248 . 10D-51 . ..... do.. ...
Waynesboro along Tennessee Route13; cut 0.4 mile south of Buffalo
River bridge and near culvert onwest side of highway 0.15 mile northof bridge.
10D-52 _ . ... ..do ....
From main intersection in Flatwood
247(Perry County), 1.0 mile east on
Tennessee Route 13, just southeast of
county line; cut on west side of
highway.
._ From junction with Tennessee Route248
11C-58 Perry, Tenn
20 in Linden, south 1.2 miles on State
Route 13 and east about 0.4 mile;then along path to abandoned quarry
0.5 mile north of road; near top ofsoutheast wall of quarry.
Northeast of Linden courthouse 0.2
249.
11C-4- ___ ..domile on Tennessee Route 100; 150 ft
west of road near city pump house.
250. ... ... 11D-75- Hickman, Tenn ... 0.5 mile west of intersection in Pleasantville, on Tennessee Route 100; inlimestone quarry north of road and 30
ft above base.
251 ___
11C-74 Perry, Tenn.. .... From intersection at Beardstown, 2.8
miles south on Tennessee Route 13,
then east 1.5 miles across Bluff River;cut and gully on east side of road.
252 ....... 12C-73.
do..... .... . From Lobelvflle, north 0.6 mile on
Tennessee Route 13; cuts on bothsides of highway.
253
130-53 .... Humphreys, Tenn. About 11 miles west of courthouse at
Waverly on U.S. Highway 70;
excavation for foundations of New
Johnsonville TVA steam plant,
now concealed.
254 .
Stewart, Tenn.... North flank of Wells Creek cryptoexplosive structure, in southeasternpart of county; 0.7 mile west of arailroad grade crossing at the west
limit of Cumberland City.

84

CHATTANOOGA SHALE, EELATED BOOKS, CENTEAL TENNESSEE AND NEAEBY AEEASTABLE 14. Correlation of locality numbers
Locality No.

This
Field
report2'39
2G-1. ____ _________ _4G-l-________------ _4J-1 ____ __-__- _ _6M-1_- _ --------- _6N-53. _ -_____-___ _7N-52___---__-__-__ _8B-l-_-____-___-___ _8D-66. _ _ _ _- _8D-90_-_.__-____-__
8E-88-------------8E-89_----_----__-.
8F-ll-__---_______8J-1 _ --_-_-__-_
9B-1-. __ __-__-___ _9B-87__-________._- _9C-l_-___--_-__---_ _QD-1

9D-66 ___ _________
9D-82 ___ -__-_-_-_
9D-83--_-__-_--___
9D-84 _ . _ ---____
9F-45----_________9F-85-- __ -_-______
8F-12-_______-__-__
9F-86____--__ __-_
9G-42___. __.__-____
9G-43-___ _ __-__-9G-47___________-__
9H-48 _ __-___--__9H-17__---______.__ _9J-50- _ -___-____-_
9J-51 . ._ . _ __9N-1. ___ -_____-_- .
9N-2. __ ______ _ _ _9N-3________-__-.-_ .
10B-l_-___-_-______ _10B-2-. _ - _ -- - .
10B-3____. __._.____ _10C-1------ _ . _ 100-46- __ ______--_
10D-50. _ ____._ -- .
10D-51. _ -_-__ _ _ .
10D-52 . ______ _10D-59-__-___-___ __10E-60__-___. ___ -_10F-44_____________
10F-65-__-_______-_
10G-34_---_____-___
10G-36_---______-_.
10G-37_---_-_-___-_
10G-41_____________
10H-38- -______-__
10H-39. __ _ ____ _10H-40. ____________
10J-2 ____________ _10J-3 _ _ ________
10J-4 _ ___.____.
10J-8 ____________
10J-9 __ -___-_-_
10K-3- __ -_--_-.__
10K-4___________-__
10K-5-____-__-.____
10K-6. __ __-_-____

233
232
231
230
229
235
146
145
144
143
142
127
237
236
241
151
147
149
150
148
138
140
141
139
137
130
129
128
126
125
123
225
224
226
240
238
239
242
243
244
246
247
245
176
136
152
135
134
133
131
132
120
117
116
115
114
118
111
112
113
110

Locality No.
Field
10K-10- ___ -_-. __ _10K-11-. ___ ___ ____

10M-1 __ ____ ______ _llC-4_______-______ _110-58- __ -___--_-_
11C-74. __-_.____.__
11D-75. ____ -____. _llE-l___-__________
11E-2-. _ _-___--__
llE-3___- ____ -_.llE-5__-- ____ .___
HE-32_._ _ _______
llE-33__-_----_____
HE-69.-- _ _____-. _llF-7___ __ -___-__
11F-26--- .
_ _ _llF-28-.--_-___-_-_ _11F-29- __ ----- ___ _llF-91-_-----_---__
11J-1_ _ __
11J-6 __ _ -._ ____
UK 1. _--__--_____.
llK-2____-_-___.___
llK-16_----____-___
12C-73_----___-__-_ _12D-71-. _ -___-___
12D-72_-_--_-_-____
12E-5-_-------_ ____
12E-6__ ___ - __ ._12E-54. _ _ _____
12E-67---- __-__-_ _12E-68_________ _
12E-76.- _ _______
12E-77_____-_______ _12E-78--_-----____ _12E-79---------- .12F 24__ _-___.
12F-25------_-_---_
12F-27_.----_______
12F-30-.- __ _ _12G-8------------12G-19----------12G-20------.- _ -.
12G-21_-_--_-_- _ _ _12G-23------_-_____
12H-31_-_-_-__--__12Q-l____-_--_.____ .
13C-53-----_____--_ _13F-l___-______-__. _13F-9_------_--____
13F-22_____--__---_
13G-l-----_-__--___
13G-3.------- _ --_13G-4. .___-___-____
13G-7-_---_--_--___
13G-11 __ __________
13G-12-___-__-_-13G-55_-_-_-____--_
13G-80----__--_-___
13G-81_----_____-__
13L-8-_---___--____
13L-ll_---_-__-- ___13L-13__------_-_--

This
report

122
212
249
248
OKI

250
1 £18
15Q

160
162

156

1 ^7

161
153
179
177
174
178
105

109
107
106
108
252
163
164
168
167
1 RK

166
IfiQ
175.

170
171
172
183
184

1 SO

173
181
187
189
188
1 S9

185
213
253
200
192
190
202
1QK

199
193
195
1Q7
IQfi
61
66

67

Locality No.
Field
13L-17__. __________

This
report62
71
13L-20... __..._. __60
13L-22__.._ __ . _13M-1. ____ _ _ _.
73
74
13M-4. ___ ______
13M-5_ ___ ..._.__.
72
64
13M-7__ _ __-___-_13M-10 ___ __._.__65
13M-19 ---------63
13M-23. _ . __ -._58
13M-24 ____ _ _5970
13M-30 _ ---------13M-31 _ -_-_ __ .
69
13M-32 __ __ _68
13M-33 ---------55
57
13M-34 __________
13M-35 _ . __ -56
254
14D
14G-1._
203
201
14G-2__. __ ----___ _14G-5 __ . _ . _ . _ 203B
14G-6 __ --. ________ _ 203A
204
14G-14____-__--- _ .
205
14J-13 _ _____---_-_ .
21
14L-l_---_--____--22
14L-5_------_-----14L-6--------- _____
23
20
14L-7__-_-_- _______
54
14M-2 _ _-_-_-__ ___14M 6 ___ _ _25
14M-7 -___ _______
26
39
14M-8 _--__--__-14M-9 -__- _ -_.29
14M-10- __ -__ _1850
14M-11
14M-13_-_-__-__ -._19
14M-14 __ _ . _34
14M-15- _ _ -_43
14M-16-. _ _ _____
27
51
14M-20 ---------44
14M-21 ___ -.____45
14M-22-__. ___ _._14M-23 __________
35
14M-24- ________
41
14M-25 ____ __---30
14M-26 _ ___ __ _32
14M-27 -__ __ ._33
47
14M-29 __ __--_14M-30. __ __-_--_52
40
14M-31 ---------14M-32- _ -_. __ _46
14M-33- __ ___ .
53
36
14M-35 _ --_-__.
14M-36 __ _ _ . __37
14M-37 _____-_-__
38
49
14M-38 -____--_-24
14M-39 __----_-_14M-40. _____ --_28
14M-43. ____ -_-_48
14M-44. _ -_. __ ._42
14N-3 _ -_--___ _ _31
14N-4_____ _
17206
15J-13 ___ --------- _Locality No.
This
Field
report207
15K-2-. _ -_---____ 208
15L-3--.- ____ _-. _209
15L-4.__ ____ -_- .
210
15L-10.__ ____ --._ _15N-12 _______ ._16
16H-l__-__-_-_-__.
15
16N-1. __ ----- __14
16N-11- ____ ----13
16P-1--.- _ _______
12
16P-10------------11
16P-2-. __ ------10
16Q-3__- _____ _-_9
16Q-5-. __________
7
17P-8.-- ____ _ ___2l7P-ll________-__-_
1
17Q-4. __________ _8
l7Q-12-_-__________
3
17R-6-- ------ ____
4
17R-7.___---_-_--_
5
17R-9------- _ - ___6
BR-132 _-____-___
228
BR-133 _ -___-_---_
227
LC-l____--_---_-___
81
LC-2___--------_-_
80
LC-4____-------_-_
75
LC-6____. -_-_-__.__
84
LC-8--_--------_-_
86
LC-10.--_-_ ___ .-_78
LC-11----------88
LC-12. _____ -.__
90
LC-15 _ ---_-__-___
92
LC-l7____-_-_-_-_-_
91
LC-30-__-------__-_
89
LC-33-----_------__
87
LC-34__---__-----__
95
LC-50__-_-_-_-----83
LC-51.-----------85
LC-55___---------_
76
LC-56.-_----_-----_
82
LC-60------ _ _-_-100
LC-102__--______-__
77
LC-103_____--____-_
93
LC-105A___-__--_-_
94
211
LC-113A-------- __ _LC-201------------79
R-C1 _. ____ --.
102
R-C2 .- _ ------103
R-C3 -----------104
R-C4 ____________
99
R-C5 -----------97
R-C6 -_-_-_- -_101
R-C7 _ ___-______
98
R-C8 -----------96
220
R-Sl_-.__--------- _R-S2____--- ----221
R-S3 ___ . __ ----216
215
R-S6_. _--_-___-_.__ _218
R-S14_______.___--_ _R-S15_'___
222
217
R-S16-. _----_---_-_ _219
R-Sl7___-_-_-_-_.__ _223
R-S19------------- _Davton______-__ ___214

SELECTED REFERENCES

SELECTED REFERENCES
Adams, G. D., 1904, Zinc and lead deposits of northern Arkansas : U. S. Geol. Survey Prof. Paper 24.
Andrews, E. B., 1870, Ohio Geological Surrey progress report,
1869: p. 62.
Androssow, N., 1897, La Mer Noire: Guide des Excursions du
VII Congress Geol. Internatl., v. 29.
Bain, H. F., 1895, Central Iowa section of the Mississippian
series: Am. Geol., v. 15, p. 317-325.
Bassler, R. S., 1911, The Waverlyan period of Tennessee: U. S.
Natl. Mus. Proc., v. 41, p. 209-224.
1932, The stratigraphy of the Central Basin of Tennessee : Tennessee Div. Geology Bull. 38.
Bates, T. F., 1953, Mineralogy of the Chattanooga shale [abs.] :Geol. Soc. America Bull., v. 64, p. 1529.
Bates, T. F., and Strahl, E. O., 1957, Mineralogy, petrography,
and radioactivity of representative samples of Chattanooga
shale: Geol. Soc. America Bull., v. 68, p. 1305-1313.
Bates, T. F., Strahl, E. O., Short, N. M., Silverman, E. N., andCamilli, Elena, 1954, Mineralogy and petrography of the
Chattanooga shale [abs.]: Geol. Soc. America Bull., v. 65,
p. 1230.
Bates, T. F., Wright, H. D., Camilli, Elena, and others, 1953, An
investigation of the mineralogy, petrography, and paleobotany of uranium-bearing black shales and lignites. Scope
A shales: U. S. Atomic Energy Comm. NYO 3363, 41 p.
Beers, R. F., 1945, Radioactivity and organic content of some
Paleozoic shales: Am. Assoc. Petroleum Geologists Bull.,
v. 29, p. 1-22.
Beers, R. F., and Goodman, Clark, 1944, Distribution of radioactivity in ancient sediments: Geol. Soc. America Bull., v.
55, p. 1229-1253.
Billings, M. P., 1955, Geologic map of New Hampshire: U. S.
Geol. Survey.
Boon, J. D., and Albritton, C. C., Jr., 1938a, Established andsupposed examples of meteoritic craters and structures:
Field Lab., v. 6, p. 44-56.
1938b, The impact of large meteorites: Field Lab., v. 6,
p. 57-64.
Borden, W. W., 1874, Report of a geological survey of Clarkand Floyd Counties, Indiana: Indiana Geol. Survey 5th
Ann. Rept, p. 134-189.
Born, K. E., and Burwell, H. B., 1939, Geology and petroleum
resources of Clay County, Tennessee: Tennessee Div.
Geology Bull. 47.
Born, K. E., and Wilson, C. W., Jr., 1939, The Howell structure,
Lincoln County, Tennessee: Jour. Geology, v. 47, p. 371-388.
Bradley, W. H., 1929, The varves and climate of the Green River
epoch: U. S. Geol. Survey Prof. Paper 158-E, p. 87-110.
Branca, W., and Fraas, Eberhard, 1905, Das kryptovulkanische
Becken von Steinheim: Berlin, K. Preuss. Akad. Wiss. Abh.,p. 1-64.
Breger, I. A., and Deul, Maurice, 1956, The organic geochemistryof uranium, in Page, L. R., Stocking, H. E., and Smith, H.
B., compilers, Contributions to the geology of uranium andthorium by the United States Geological Survey and Atomic
Energy Com mission for the United Nations International
Conference on Peaceful Uses of Atomic Energy, Geneva,
Switzerland, 1955: U. S. Geol. Survey Prof. Paper 300, p.
505-510.
Breger, I. A., Meyrowitz, .Robert, and Deul, Maurice, 1954,
Effects of destructive distillation on the uranium associatedwith selected naturally occurring carbonaceous substances:
Science, new ser., v. 120, p. 310-312.

85

Breger, I. A., and Schopf, J. M., 1955, Germanium and uranium
in coalified wood from Upper Devonian black shale: Geochim. et Cosmochim. Acta, v. 7, p. 287-293.
Bucher, W. H., 1936, Cryptovolcanic structures in the UnitedStates: Internat. Geol. Gong., 16th, 1933, Kept., v. 2, p. 10551084.
Butts, Charles, 1911, Description of the Birmingham quadrangle[Alabama] : Field ed., U. S. Geol. Survey Geol. Atlas Folio
175.
1919, Geology and oil possibilities of the northern partof Overton County, Tennessee, and of adjoining parts ofClay, Pickett, and Fentress Counties: Tennessee Div.
Geology Bull. 24, Ann. Rept. 1919, pt. 2-A.
Campbell, Guy, 1946, New Albany shale: Geol. Soc. America
Bull., v. 57, p. 829-908.
Cayeux, Lucien, 1897, Contribution a 1'etude micrographiquedes terrains sedimentaires: Mem. Soc. Geol. Nord., v. 26,
pt 2, p. 168-187.
Clarke, F. W., 1924, The data of geochemistry: 5th ed., U. S.
Geol. Survey Bull. 770.
Clarke, J. M., 1885, On the higher Devonian faunas of Ontario
County, New York: U. S. Geol. Survey Bull. 16.
1904, Naples fauna in western New York: New YorkState Mus. Mem. 6, p. 199-454.
Cline, L. M., 1934, Osage formations of southern Ozark region,
Missouri, Arkansas, and Oklahoma: Am. Assoc. Petroleum
Geologists Bull., v. 18, p. 1132-1159.
Cloud, P. E., 1955, Physical limits of glauconite formation: Am.
Assoc. Petroleum Geologists Bull., v. 39, p. 484-492.
Conrad, S. G., Elmore, R. T., Jr., and Maher, S. W., 1954,
Stratigraphy of the Chattanooga black shale in the Flynn
Creek structure, Jackson County, Tennessee [abs.]: Geol.
Soc. America BulL, v. 65, p. 1358.
1957, Stratigraphy of the Chattanooga black shale in the
Flynn Creek structure, Jackson County, Tennessee: Tennessee Acad. Sci., Jour., v. 32, No. 1, p. 9-18.
Cooper, C. L., 1948, in Weller, J. M., chairman, Correlation of
the Mississippian formations of North America: Geol. Soc.
America Bull., v. 59, p. 91-196.
Cooper, G. A., and others, 1942, Correlation of the Devonian
sedimentary formations of North America: Geol. Soc.
America Bull., v. 53, chart 4, p. 1729-1793.
1957, Paleoecology of Middle Devonian eastern and central United States, in Ladd H. S. ed., Paleoecology, v. 2 ofTreatise on marine ecology and paleoecology: Geol. Soc.
America Mem. 67, p. 249-277.
Grouse, C. S., 1925, An economic study of the black Devonian
shales of Kentucky, in Thiessen, Reinhardt, and others,
Oil shales of Kentucky: Kentucky Geol. Survey, ser. 6, v.
21, p. 59-97.
Cuttitta, Frank, 1953, A photometric method for the estimationof the oil yield of oil shale, in Brannock, W. W., and others,
Contributions to geochemistry, 1949: U. S. Geological Survey Bull. 992, pt. 2, p. 15-31.
Dawson, J. W., 1876, Note on the phosphate of the Laurentian
and Cambrian rocks of Canada: Geol. Soc. London Quart.
Jour., v. 32, p. 285-291.
Deul, Maurice, 1957, Geochemistry of uranium-bearing shale, inGeologic investigations of radioactive deposits Semiannual progress report, June 1-Nov. 30, 1957: U. S. Geol.
Survey Trace Elements Memo. Repts., p. 213-224.
Dietz, R. S., 1946, Geological structures possibly related to
lunar craters: Pop. Astronomy, v. 54, p. 465-467.

86

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

Dietz, R. S., Emery, K. O., and Shepard, F. P., 1942, Phosphorite
deposits on the sea floor off southern California: Geol. Soc.
America Bull., v. 53, p. 815-847.
Dietz, R. S., and Menard, H. W., 1951, Origin of abrupt change
in slope at continental shelf margin: Am. Assoc. Petroleum
Geologists Bull., v. 35, p. 1994-2016.
Dunbar, C. O., 1919, Stratigraphy and correlation of the Devonian of western Tennessee: Tennessee Geol. Survey Bull. 21.
Edwards, Ira, and Rassche, Gilbert, 1922, Notes on the occurrence of Upper Devonian strata in Wisconsin: Public
Museum of City of Milwaukee Yearbook, 1921, v. 1, p. 88-93.
Ellison, S. P., Jr., 1946, Conodonts as Paleozoic guide fossils:
Am. Assoc. Petroleum Geologists Bull., v. 30, p. 93-110.
Fenneman, N. M., 1938, Physiography of eastern United States:
New York, McGraw-Hill Book Co.
Fettke, C. R., 1952, Tioga bentonite in Pennsylvania and adjacent States: Am. Assoc. Petroleum Geologists Bull., v.
36, p. 2038-2040.
Flowers, R. R., 1952, Lower Middle Devonian metabentonite inWest Virginia: Am. Assoc. Petroleum Geologists Bull., v.
36, p. 2036-2038.
Foerste, A. F., 1901, Silurian and Devonian limestones of Tennessee and Kentucky: Geol. Soc. America Bull., v. 12, p.
395-444.
Freeman, L. B., 1951, Regional aspects of Silurian and Devoniansubsurface stratigraphy in Kentucky: Am. Assoc. Petroleum Geologists Bull., v. 35, p. 1-61. Also published by Kentucky Geological Survey as ser. 9, reprint 2, and as Bull. 6.
Galloway, J. J., 1919, Geology and natural resources of Rutherford County, Tennessee: Tennessee Div. Geology Bull. 22.
Girty, G. H., 1898, Description of a fauna found in the Devonian
black shale of eastern Kentucky: Am. Jour. Sci., 4th ser.,v. 6, p. 384-395.
Glover, Lynn, 1959, Stratigraphy and uranium content of the
Chattanooga shale in northeastern Alabama, northwestern
Georgia, and eastern Tennessee: U. S. Geol. Survey Bull.
1087-E, p. 133-168.
Goldman, M. I., 1922, Basal glauconite and phosphate beds:
Science, new ser., v. 56, p. 171-173.
1924, "Black shale" formation in and about Chesapeake
Bay: Am. Assoc. Petroleum Geologists Bull., v. 8, p. 195201.
Grabau, A. W., 1906, Types of sedimentary overlap: Geol. Soc.
America Bull., v. 17, p. 567-636.
Grabau, A. W., and O'Connell, Marjorie, 1917, Were the graptolite shales, as a rule, deep or shallow water deposits?:
Geol. Soc. America Bull., v. 28, p. 959-964.
Hard, E. H., 1931, Black shale deposition in central New York:
Am. Assoc. Petroleum Geologists Bull., v. 15, p. 165-181.
Hass, W. H., 1948, Upper Devonian bentonite in Tennessee: Am.
Assoc. Petroleum Geologists Bull., v. 32, p. 816-819.
1953, Age of the Chattanooga shale and Maury formation[abs.] : Geol. Soc. Am. Bull., v. 64, p. 1532.
1956, Age and correlation of the Chattanooga shale andthe Maury formation: U. S. Geol. Survey Prof. Paper 286.
Hass, W. H., and Lindberg, M. L., 1946, Orientation of thecrystal units of conodonts: Jour. Paleontology, v. 20, p.
501-504.
Hayes, C. W., 1891, The overthrust faults of the southern
Appalachians: Geol. Soc. America Bull., v. 2, p. 141-154.

1892, Report on the geology of northeastern Alabama andadjacent portions of Georgia and Tennessee: Alabama
Geol. Survey Bull. 4.
1894a, Description of the Ringgold quadrangle [GeorgiaTennessee] : U. S. Geol. Survey Geol. Atlas, Folio 2.
1894b, Description of the Kingston quadrangle [Tennessee] : U. S. Geol. Survey Geol. Atlas, Folio 4.
1894c, Description of the Chattanooga quadrangle [Tennessee] : U. S. Geol. Survey Geol. Atlas, Folio 6.
1894d, Description of the Sewanee quadrangle [Tennessee] : U. S. Geol. Survey Geol. Atlas, Folio 8.
1895, Description of the Cleveland quadrangle [Tennessee] : U. S. Geol. Survey Geol. Atlas, Folio 20.
1896, The Tennessee phosphates: U. S. Geol. Survey 17th
Ann. Rept., pt. 2, p. 513-550.
1899, Physiography of the Chattanooga district in Tennessee, Georgia, and Alabama: U. S. Geol. Survey 19th Ann.
Rept., pt. 2, p. 1-58.
Hayes, C. W., and Ulrich, E. O., 1903, Description of theColumbia quadrangle [Tennessee] : U. S. Geol. Survey Geol.
Atlas, Folio 95.
Hedberg, H. D., 1926, The effect of gravitational compaction on
the structure of sedimentary rocks: Am. Assoc. Petroleum
Geologists Bull., v. 10, p. 1035-1072.
Hollingsworth, S. E., and Bannister, F. A., 1950, Basaluminite
and hydrobasaluminite, two new minerals from Northamptonshire : Mineralog. Mag., v. 29, p. 1-17.
Holmes, G. B., 1928, A bibliography of conodonts with descriptions of early Mississippian species: U. S. Natl. Mus. Proc.,v. 72, art. 5, 38 p.
Huddle, J. W., 1933, Marine fossils from the top of the New
Albany shale of Indiana: Am. Jour. Sci., 5th ser., v. 25, p.
303-314.
Jewell, W. B., 1931, Geology and mineral resources of Hardin
County, Tennessee: Tennessee Div. Geology Bull. 37.
Jillson, W. R., 1951a, Geology of Cumberland County, Kentucky : Frankfort, Ky., Roberts Printing Co.
1951b, The Burkesville limestone: Frankfort, Ky., RobertPrinting Co.
Kay, Marshall, 1951, North American geosynclines: Geol. Soc.
America Mon. 48, 143 p.
Kehn, T. M., 1955, Uranium in the Chattanooga shale, Youngs
Bend area, Eastern Highland Rim, Tennessee: U. S. Geol.
Survey TEI-528-A, issued by U. S. Atomic Energy Comm.
Tech. Inf. Service, Oak Ridge, Tenn.
Keulegan, G. H., and Krumbein, W. C., 1949, Stable configuration of bottom slope in a shallow sea and its bearing on
geological processes: Am. Geophys. Union Trans., v. 30, p.
855-861.
Kindle, E. M., 1912, The unconformity at the base of the Chattanooga shale in Kentucky: Am. Jour. Sci., 4th ser., v. 183,
p. 120-136.
King, P. B., 1950, Tectonic framework of southeastern UnitedStates: Am. Assoc. Petroleum Geologists Bull., v. 34, p.
635-671.
1951, The tectonics of middle North America: Princeton
Univ. Press, 220 p.
King, P. B., and others, 1944, Tectonic map of the UnitedStates: Am. Assoc. Petroleum Geologists.
Kinney, C. R., Broadhead, R. L., Leonard, J. T., Roessing, T. J.,
Chen, J. P., and Weinstein, A,, 1957, An investigation of
the chemical nature of the organic matter of uraniferous
shales: U. S. Atomic Energy Comm. NYO-6677, 42 p.

SELECTED REFERENCES
Kinney, C. R., Leonard, J. T., Chem. J. P., and Weinstein, A.,
1958, An investigation of the chemical nature of the organic
matter of uraniferous shale, in Semiannual report covering
the period October 1,1957 to March 31,1958: U. S. Atomic
Energy Comm. NYO-6678.
Klepser, H. J., 1937, The Lower Mississippian rocks of the Eastearn Highland Rim: Ohio State Univ. Abs. Doctoral Dissert., v. 24, p. 181-187.
Koczy, F. H., 1954, Geochemical balance in the hydosphere, inFaul, Henry, ed., Nuclear geology: New York, John Wiley& Sons, Inc.
Langbein, W. B., and others, 1949, Annual runoff in the UnitedStates: U. S. Geol. Survey Circular 52.
Lapworth, Charles 1889, On the Ballantrae rocks of south
Scotland and their place in the upland sequence: Geol.
Mag., new ser., December 3, v. 6, p. 20-24, 59-69.
Lucke, J. B., 1935, Bottom conditions in a tidal lagoon: Jour.
Paleontology, v. 9, p. 101-107.
Lusk, R. G., 1927, A pre-Chattanooga sink hole: Science, newser., v. 65, p. 579-580.
Maher, S. W., and Dunkle, D. H., 1955, An occurrence of apleuropterygian shark in the Chattanooga shale of Tennesee: Tennessee Acad. Sci. Jour., v. 30, p. 202-203.
Marble, J. P., 1950, Report of the Committee on the measurement of geologic time, 1949-1950: Natl. Research Council
Div. Geology and Geography, p. 1-24.
Marr, J. E., 1925, The Stockdale shales of the Lake District:
Geol. Soc. Quart Jour., v. 81, pt. 2, p. 113-133.
Mather, K. F., 1920, Oil and gas resources of the northeasternpart of Sumner County, Tennessee: Tennessee Div. Geology
Bull. 24, Ann. Rept. 1919. pt. 2-B.
McKelvey, V. E., and Nelson, J. M., 1950, Characteristics ofmarine uranium-bearing sedimentary rocks: Econ. Geology,
v. 45, p. 35-53.
Mellen, F. F., 1947, Black Warrior basin, Alabama and Mississippi: Am. Assoc. Petroleum Geologists Bull., v. 31, p.
1801-1816.
1955, Subsurface outliers of Chattanooga shale in northeastern Mississippi: Am. Assoc. Petroleum Geologists Bull.,v. 39, p. 1864-1865.
Milton, Charles, Conant, L. C., and Swanson, V. E., 1955, SubChattanooga residuum in Tennessee and Kentucky: Geol.
Soc. America Bull., v. 66, p. 805-810.
Miser, H. D., 1921, Mineral resources of the Waynesboro quadrangle, Tennessee: Tennessee Div. Geology Bull. 26.
Moore, G. W., 1954, Extraction of uranium from aqueous solution by coal and some other materials: Econ. Geology, v.
49, p. 652-658.
Moore, R. C., 1929, Environment of Pennsylvanian life in North
America: Am. Assoc. Petroleum Geologists Bull., v. 13, p.
459-487.
1949, Meaning of facies, in Longwell, C. R., and others,
Sedimentary facies in geologic history: Geol. Soc. America
Mem. 39, p. 1-34.
Morse, W. C., 1930, Paleozoic rocks [of Mississippi] : Mississippi
Geol. Survey BulL 23.
Morse, W. C., and Foerste, A. F., 1909, The Waverly formationsof east-central Kentucky: Jour. Geology, v. 17, p. 164-177.
Nelson, W. A., 1913, Mineral products along the Tennessee
Central Railroad: Resources Tenn., v. 3, no. 3, p. 137-160.

87

Pepper, J. F., and deWitt, Wallace* Jr., 1950, Stratigraphy of
the Upper Devonian Wiscoy sandstone and the equivalentHanover shale in western and central New York: U. S.
Geol. Survey Oil and Gas Inv. Prelim. Chart 37.
Pettijohn, F. J., 1949, Sedimentary rocks: New York, Harper& Bros.
Pohl, E. R., 1930, The black shale series of central Tennessee:
Am. Jour. Sci., 5th ser., v. 20, p. 151-152.
Price, P. H., and Woodward, H. P., 1940, Resume of the
Devonian system of West Virginia: Am. Assoc. Petroleum
Geologists Bull., v. 24, p. 1983-1994.
Rich, J. L., 1948, Probable deep-water origin of the MarcellusOhio-New Albany-Chattanooga black shale [abs.]: Geol.
Soc. America Bull., v. 59, p. 1346-1347.
1951a, Three critical environments of deposition andcriteria for recognition of rocks deposited in each of them:
Geol. Soc. America Bull., v. 62, p. 1-20.
1951b, Probable fondo origin of Marcellus-Ohio-New
Albany-Chattanooga bituminous shales: Am. Assoc. Petroleum Geologists Bull., v. 35, p. 2017-2040.
1953, Paleogeographic implications of evidences pointing
to fondo origin of the Chattanooga-New Albany-Ohio
bituminous shale [abs.] : Geol. Soc. America Bull., v. 64,
p. 1535-1536.
Ross, C. S., 1955, Provenience of pyroclastic materials: Geol.
Soc. America Bull., v. 66, p. 427-434.
Rubey, W. W., 1930, Lithologic studies of fine-grained Upper
Cretaceous sedimentary rocks of the Black Hills region:
U. S. Geol. Survey Prof. Paper 165-A, p. 1-54.
Ruedemann, Rudolf, 1934, Paleozoic plankton of North
America: Geol. Soc. America Mem. 2.
Russell, W. L., 1944, The total gamma-ray activity of sedimentary rocks as indicated by Geiger counter determinations: Geophysics, v. 9, p. 180-216.
1945, Relation of radioactivity, organic content, and sedimentation: Am. Assoc. Petroleum Geologists Bull., v. 29,
p. 1470-1493.
Safford, J. M., 1851, The Silurian system of middle Tennessee,with notices of the strata surrounding it: Am. Jour. Sci.,
2d ser., v. 12, p. 352-361.
1856, A geological reconnaissance of the State of Tennessee: First biennial report presented to the Thirty-first
General Assembly of Tennessee: Nashville, 164 p.
-1869, Geology of Tennessee: Nashville, 551 p.
Safford, J. M., and Killebrew, J. B., 1900, The elements of thegeology of Tennessee: Nashville, 246 p.
Savage, T. E., 1930, The Devonian rocks of Kentucky: Kentucky
Geol. Survey, ser. 6, v. 33.
Savage, T. E., and Sutton, A. H., 1931, Age of the black shalein south-central Kentucky: Am. Jour. Sci., 5th ser., v. 22,
p. 441-448.
Schuchert, Charles, 1910, Paleogeography of North America:
Geol. Soc, America BulL, v. 20, p. 427-606.
1915, The conditions of black shale deposition as illustrated by the Kupferschiefer and Lias of Germany: Am.
Philosophical Soc. Proc. 54, p. 259-269.
Shepard, F. P., 1948, Submarine geology: New York, Harper &Bros.
Smith, R. W., and Whitlatch, G. I., 1940, The phosphate resources of Tennessee: Tennessee Div. Geology Bull. 48.
Stockdale, P. B., 1939, Lower Mississippian rocks of the eastcentral interior: Geol. Soc. America Spec. Paper 22.

88

CHATTANOOGA SHALE, RELATED ROCKS, CENTRAL TENNESSEE AND NEARBY AREAS

Strahl, E. O., Camilli, Elena, Short, N. M., and others, 1954, An
investigation of the mineralogy, petrography and paleobotany of uranium-bearing shales and lignites. Scope Ashales: U. S. Atomic Energy Comm. NYO-6060, 70 p.
Strahl, E. O., Silverman, E. O., O'Neil, R. L., and others, 1955,
An investigation of the mineralogy, petrography, and paleobotany of uranium-bearing shales and lignites. Scope Ashales: U. S. Atomic Energy Comm. NYO-6068, 79 p.
Strom, K. M., 1948, A concentration of uranium in black muds:
Nature, v. 162, p. 922.
Sverdrup, H. V., Johnson, M. W., and Fleming, R. H., 1942, Theoceans: New York, Prentice-Hall, Inc.
Swartz, J. H., 1924, The age of the Chattanooga shale of Tennessee: Am. Jour. Sci., 5th ser., v. 7, p. 24-30.
1926, The age of the Big Stone Gap shale of southwestern
Virginia: Am. Jour. Sci., 5th ser., v. 12, p. 522-531.
1927, The Chattanoogan age of the Big Stone Gap shale:
Am. Jour. Sci., 5th ser., v. 14, p. 485-499.
1929, The age and stratigraphy of the Chattanooga shale
in northeastern Tennessee and Virginia: Am. Jour. Sci.,
5th ser., v. 17, p. 431-448.
Trask, P. D., 1951, Depositional environment of black shale:
Program 1951 Ann. Mtg., Am. Assoc. Petroleum Geologists,
St. Louis, Mo., April 23-26, p. 44.
Troost, Gerard, 1835, Third geological report to the Twentyfirst General Assembly of the State of Tennessee: Nashville, 32 p.
1837, Fourth geological report to the Twenty-second
General Assembly of the State of Tennessee: Nashville,
37 p.
1840, Fifth geological report to the Twenty-third General
Assembly of Tennessee: Nashville, 75 p.
1841, Sixth geological report to the Twenty-fourth
General Assembly of the State of Tennessee: Nashville,
48 p.
-1843, Seventh geological report to the Twenty-fifth
General Assembly of the State of Tennessee: Nashville,
45 p.
Twenhofel, W. H., 1915, Notes on black shale in the making:Am. Jour. Sci., 4th ser., v. 40, p. 272-280.
1932, Report of the Committee on Sedimentation, 19301932: Natl. Research Council Bull. 89, p. 5-19.
1939, Environments of origin of black shales: Am. Assoc.
Petroleum Geologists Bull., v. 23, p. 1178-1198.
Ulrich, E. O., 1911, Revision of the Paleozoic systems: Geol. Soc.
America Bull., v. 22, p. 281-680.

1912, The Chattanoogan series with special reference tothe Ohio Shale problem: Am. Jour. Sci., 4th ser., Y. 34,.
p. 157-183.
Ulrich, E. O., and Bassler, R. S., 1926, A classification of thetoothlike fossils, conodonts, with descriptions of American*
Devonian and Middissippian species: U. S. Natl. Mus. Proc.,v. 68, art. 12, 63 p.
Ulrich, E. O., and Smith, W. S. T., 1905, The lead, zinc, andfluorspar deposits of western Kentucky: U. S. Geol. Survey
Prof. Paper 36.
Washburne, C. W., 1937, Salt domes, meteor craters, andcryptovolcanic structures: Am. Assoc. Petroleum GeologistsBull., v. 21, p. 629-630.
Weaver, C. E., Wright, H. D., and Bates, T. F., 1952, Annual!
progress report on investigations of the mineralogy andpetrography of uranium-bearing shales, July 1, 1951, to>April 1, 1952: U. S. Atomic Energy Commission NYO-3357.
Weller, J. M., and others, 1948, Correlation of the Mississippian.
formations of North America: Geol. Soc. America Bull., Y.
59, p. 91-196.
Whitlatch, G. I., 1948, Carbsil Pigment Company: TennesseeState Planning Comm. Newsletter, p. 4, Nashville, Tenn.
Also printed, in modified form, ~by W. H. S., 1948, Pay Dirt r
Indus. Eng. Chemistry, v. 40, December, p. 22A-24A.
Wilmarth, M. G., 1938, Lexicon of geologic names of the United1
States (including Alaska) : U. S. Geol. Survey Bull. 896.
Wilson, C. W., Jr., 1935, Pre-Chattanooga development of the
Nashville dome: Jour. Geology, v. 43, p. 449-481.
1949, Pre-Chattanooga stratigraphy in central Tennessee:
Tennessee Div. Geology Bull. 56.
[1951?], Geologic map of central Tennessee: Prelim, ed.,Tennessee Div. Geology (one color; scale 1 inch = 1 mile).
Wilson, C. W., Jr., and Born, K. E., 1936, The Flynn Creek
disturbance, Jackson County, Tennessee: Jour. Geology, Y.
44, p. 815-835.
Wilson, C. W., Jr., and Spain, E. L., Jr., 1936, Age of Mississippian "Ridgetop shale" of central Tennessee: Am. Assoc.
Petroleum Geologists Bull., v. 20, p. 805-809.
Woolnough, W. G., 1937, Sedimentation in barred basins, andsource rocks of oil: Am. Assoc. Petroleum Geologists Bull.,
v. 21, p. 1101-1157.

Workman, L. E., and Gillette, Tracey, 1956, Subsurface stratigraphy of the Kinderhook series in Illinois: 111. State Geol.
Survey Rept. Inv. 189.

INDEXA

Page

Acadian orogeny_________________________________
51
Accumulation rate, sediment___________________________ 64-55
Acknowledgments________________________________ 4-5
Age assignments, Chattanooga shale.______________________ 21,22
comparison with Campbell's________________________
22
Maury formation_________________________________ 22,62
Aggregate, light-weight______________________________
69
Analyses, Chattanooga shale___________________________
43
phosphate nodules.______________________________
70
uranium in Chattanooga shale____________________ 71,74,75,76
vitrain from Chattanooga shale_______________________
47
Appalachian Valley and Ridge, surface feature_________________ 6,8
Assays, oil shale________________________________ 69, pi. 17
B
Basal sandstone of Chattanooga shale, age___________________
25
character and distribution..___________________________ 23-25
origin.. ._ __ _________________________ 53,61
petrography.._.______________________________
44
relation to "blue phosphate"-..________________________ 27-28
relation to Hardin sandstone __..____________________
28
Basal sandstone of Gassaway member_ __________________
35
Basal sandstone of Maury formation________________________ 25, 44
Basaluminite .
_ ___ ___._______
16
Bassler, R. S., age of Chattanooga shale..___________________
18
quoted...____ _______________________________
62
Batelle Memorial Institute, analyses by____________________
43
Bentonite, Dowelltown member..
_._____ 30-32, 46, 54, pis. 6, 9
Black shale, relation to gray claystone__..____________________ 55-56"Blue phosphate," composition.---- . ..___._____________
47
relation to Hardin sandstone_________________________ 27-28
source of sediment___ ____..____.__
53
Bones, Chattanooga shale.... . .. ____________ 20-21, 44, 45, 47
Brachiopods, significance___ _ ________________ 21,62, 67
Bransford sandstone, history of name___.__________________
23
petrography
45
source of sediment _ _ __________________
68
thickness____ __...._________________________
35
Breger, I. A., and Deul, Maurice, quoted..___________________
73
O
Calcite.... .-... .-... .-.. .....-.-.....-...... .-.. .......... 44,48
Callixylon.......,_. __ _________________
19
Cameron Hill, Chattanooga, Tenn., exposure of Chattanooga shale______
12
Campbell, Guy, age and nomenclature of Chattanooga shale______ 19,22-23,35
nomenclature of Maury formation_____________________ 22,63
quoted- _. __._____.________
67
Carbonaceous material, denned ________________________ 6,9
significance of preservation- _________________________
60
Center Hill bentonite, age____________________________
32
character and distribution____________________ 4, 30-32, pis. 6, 9
mica.
__ ____.___________________
46
source of sediment..____________________________ 31-32,53
Chalcedony-___________________________________
48
Chattanooga sea, environmental conditions____________________ 56-62
Chattanooga shale, age.._______________________________ 16-21
analyses ..__ ___....._____________________ 43,70,71
composition-____________________________________ 42-48
distribution_________....__._____________ 4CM2, pis. 1,12, 14
environment of deposition.. ___.____________________ 56-62
extent.. .
. ___._________________ 49,50,51-52
falls at Fall Creek.._____.____________________.___ 7, pi. 2
Flynn Creek cryptoexplosive feature_._______ 10-12,30,38,55,61, pis. 4, 7
fossils.
_..- . 19-21, 35, 41-42, 62, 63, pi. 5
history of name..... __....________________________ 12-13
indications of deep-water origin___...___.____________._ 59-60
indications of shallow-water origin__ __ __-_____ ... 60-62
paleogeography during Late Devonian time..-.
-..
. ... 48-52

Chattanooga shale Continued
Page
pre-Chattanooga surface..
13-16
reason for absence in certain areas.._42
relation to Maury formation__... 8, 36, 62, 64, 65, pis. 10,13,16
section....____ -___.
.
. 24,27,37,38,63,64
sedimentation..
52-56
stratigraphy____ _...
.
.
.... 8,21-40
thickness __.. . . 8,14, 71, pi. 15
uranium content_
47,70-76
Chemical determinations, Chattanooga shale_. 43,47,70,71
Chert, in Chattanooga shale.
23,48,53
Chlorite. . ..._
48
Clarke, J. M., quoted....
57
Classifications, stratigraphic
21-23
Clay....___._.__.
46
Claystone, defined_
6
ia Dowelltown member__
30,33,55-56
Coal. See Vitrain.
Color terms, used in report...
6
Compaction, sediment.
10,55
Conodonts, named__
19-20,27,35,63
significance for age of shale..
- .
16,23,54
Correlation of locality numbers.
84
Cross Key, Tenn., section of Maury formation
63,64
Cryptoexplosive structural features
9-12
Cumberland Plateau, surface feature.-...
.. 6,8
Deep water, indications for origin of shale.
59-60
meaning of term..
57
Definition of terms...
.
5-6
Deposition, rate..
54-55
Determination of uranium..
.
_71
Deul, Maurice, and Breger, I. A., quoted
73
Dowelltown member, age____ ____.____ ....__ .
19extent and thickness___________________ 28-29, 30, 33-34, pis. 7, 8
fossils..___..__________.__________._____ 19-20, 27, 63, pi. 5
lithologic character_____.
28, pis. 6, 8, 10
lower and upper contacts. _29, pis. 4, 5
lower unit_______________________._________ 29-30, pi. 10
petrography_________
44,45
section. _....________.__________________.. 24,27,37,38,63
term used by Campbell..._
__
....
22-23
upper unit, alternation of beds
55-56
bentonite________.
30-32, pis. 6, 9
correlation of individual beds _.
32-33
extent and thickness___________________-__ 33-34, pis. 7, 8
general characteristics_______ .___ .... -. . 30, pis. 6, 9
uranium content______
.
.
71,74
Drill holes, Chattanooga shale..._________________ 4,5,37,38,71,72,73,74
Dunkel, D. H., quoted ...__.
.
20
E
Eastern Highland Rim. -See Highland Rim.
Economic geology, light-weight aggregate.. ...
69
oil shale. . -. .
.
. 69-70, pi. 17
phosphate___________.
70
pigment______ . .
70
sulfuric acid.___70
uranium.
70-76
Ellison, S. P., Jr., quoted
16
Environment of deposition, Chattanooga shale...__._.__ _ 56-62
F
Feldspar._____________ ____
Fieldwork_______.
Fine grain of shale, significance.
Fish fossils....____- ___- .
Flynn Creek cryptoexplosive area_

43,44,45,46
4-5
56,59
20-21,48
10-12, 25, 30, 55, 61, pi. 4

90

INDEX

Page
Foerste, A. F., quoted.. ._....
54
Foerste, A. F., and Morse, W. C., age of Chattanooga shale. _.
17
Fort Payne chert, contact with Maury formation_._ ..... 68, pis. 10,13,16
Flynn Creek cryptoexplosive feature.
10
physiographic expression__
7-8
stratigraphy....
9, pi. 4
Fossils, Bransford sandstone__ .
35Chattanooga shale._______.... ..
19-21, 27. 35, 62, 63, pi. 5
Maury formation.
67
Freeman, L. B., quoted
13
Q
Galena.._____________________________________
48
Gamma-ray log, Chattanooga shale and Maury formation_
74
Gassaway member, age . - . _ .
20basis for subdivision.
36
extent and thickness__.
35-36, pis. 7,10,12
fossils.... .
... 20,35,63
lithologic characteristics.
34-35, pis 6, 9-11,16
lower and upper contacts_
29,36, pis. 4,5
lower unit.. ...
. ___~_____ 36-39
middle unit... _ . ________ 39, pi. 13
petrography..
44,45
section..... . .
__._.
._.. 24,27,37,38,63
term used by Campbell__..__.. 22-23
upper unit
40, pis. 6,10,11
uranium content...,.
.._ 71,74-76
Geology, economic_.
_______ 69-76
general.
8-12
Geosyncline, major tectonic element...._ 48-51
source of sediment...._____ 52,54
Germanium___________ 47-48
Girty, G. H., age of Chattanooga shale...
.._..
17
Glauconite, Chattanooga shale_.._____
48
Maury formation..
...__ 64,65,68
Glendale shale..
21
Grabau, A. W., age of Chattanooga shale..
_____
17
H
Hard, E. H., quoted_.
.
____
58
Hardin sandstone member, age.
....___ 27-28
character and distribution..
......_ 25-27
history of name________
23
petrography.....
. ..___
44
section.....
......___
27
Hass, W. H., age of Chattanooga shale.....
_ 2,4,17,18,20,21
age of Maury formation_. ____ 2,8,67
Hayes, C. W., age of Chattanooga shale....
._________
17
history of name of formation_._____._______ 12,13
Highland Rim, surface feature..
....__ 6,7,8
Historical summary, age of Chattanooga shale.. . .________ 16-21
environment of deposition of black shale..
. ____ 57-59
History of name, Chattanooga shale..
.__ 12-13
Maury formation. . ...
.....
63
Hohenwald platform.___._._____ . ...._______ 41,50,53, pi. 15
Howell cryptoexplosive feature..... 10,12
Huddle, J. W., age of Chattanooga shale..
..___18
Elite........ .-..-.-..
Interior platform, major tectonic elementInvestigation methods....................

43,46
51
4

Kaolinite.
.
_
46
Killebrew, J. B., and Safford, J. M., quoted......_.. ..________ 63,65
Kindle, E. M., quoted.......__......_....... ..
...._..___
17
Kinney, C. R., and others, quoted_..
..__..
75
Klepser, H. J., age of Chattanooga shale. ____
18............... .................
60
Lag-concentrates, significance__....... . . .........___....
51
Landmass, major tectonic element_-.
.
__
52
source of sediment . ....
Lexington Basin, area of outcrops.,_ ... . -.. _-__.__.__
3.
.
_..._..
76
uranium content of shale ......
Lingula........... ...._._._..........
..................... 19,62,67
Locality numbers_..
..... .
.
__.... 6,84
Locah'ty register.
.....____. _.__ 77-83,84
Location of area__ ........_____ . ...______.____ 3-4

MMarcasite__
46-47
Mather, K. F., age of Chattanooga shale
17
Maury formation, age and classification .
2,8,13,21,22,42,67
analyses_...
70
description...
. .
.... .... ...
- 63, pi. 16
extent and thickness
66-67, pi. 1
fossils.____.. __.
- - .... 63,67
genetic significance_
67,68-69
history of name...
13,21,63
lower and upper contacts
67-68, pis. 5,13,16
phosphate nodules__65-66,70, pi. 16
pronunciation of name...
2
reasons for treating as separate formation ___... ....__
62
relation to Chattanooga shale____..._..____________ 32,62,64-65
Maury formation, section._______________. _____ 24,27,37,38,63,64
suggested standard locality.
63
uranium___..._
74
Measurements, linear, used in report.
-...__
6Mica.
..
.
30-31,44,46
Mineralogy, Center Hill bentonite.
. ... . ....... 30-31,46
Chattanooga shale.... .
....
____ 42-48
phosphate nodules....
.
.
...__... 47,66
Moore, R. C., quoted.. ..... . .
_____________...
58
Morse, W. C., age of Chattanooga shale ..._______________...
18
quoted .
.
58
Morse, W. 0., and Foerste, A. F., age of Chattanooga shale
. __
17
N
Nashville Basin, area of outcrops
3, pi. 1
surface feature
6,7
New Albany shale, age
18history of name____________.. -.--... ._________
13
New Providence shale
9,22,62,66
Nomenclature, comparison with Campbell's......_
22
Northern Highland Rim. See Highland Rim.
Ohio shale, age
history of nameOil shale....................... .......__...
Outcrop localities___ .
Ozarkianland area ____ ...

17,18
13
..
3, 69-70, pi. 17
4, 77-83, 84, pi. 1.
42,51,52,63

Paleogeography, Late Devonian_______.__.__ ___ .. 48-52, pL 14
Paleogeology, Late Devonian..
8,13-14, pL 3
Paleotectonic features, Late Devonian.
48,50,51
Pennsylvania State University studies_
42,43,45,46
Petrographic determinations, Chattanooga shale..
.
43-45
Phosphate, Chattanooga shale_....
.
. 19,35,43,47,60.70,76
Phosphate nodules, analyses...
43,66,70
economic possibilities.
70
Maury formation_
65-66, 70, pis. 13,16
significance47,55,60,66,68
Physiography....
6-8
Pigment..
70
Plant matter, Chattanooga shale.
19, 47-48, 59, pi. 5
Pohl, E. R., age of Chattanooga shale..
18
Trousdale shale_
19,22,23,28
Pre-Chattanooga surface, general character......
13-14, pis. 3, 5
sub-Chattanooga residuum___.. 14-16, pi. 5
Purpose of study..
3
Pyrite, in shale.
. ~.... 30,43,46-47,70
relation to uranium...
...
73
Quartz- __. .__...

Q._-__._-_.__ 30, 43, 44, 45, 59, pi. 11

R
Radioactivity. See Uranium.
Radiolaria, Chattanooga shale
Maury formation
Register of localities....
Residuum. See Sub-Chattanooga residuum.
Rich, J. L., quoted.
Ridgetop shale...
.
Ripple-marks, significanceRock terms, defined..
Ross, Clarence S., quoted_..
Ruedemann, Rudolf, quoted...

. .
.

21
66
77-83

___ ___
57.. ..
9,42,62
39,59-60
5-6
31
.
57

91

INDEX

Page

S
Page
Safford, J. M., age of Chattanooga shale _ ______________
17
history of name of Chattanooga shale.
.
.
. ... 12,13
history of name of Maury shale..
_ _ ... _ 13,21
quoted...
2,3,7Safford, J. M., and Kfflebrew, J. B., quoted. 63,65
Sample numbering system.___ .... _ _ _._ _ __6
Samples, for uranium analysis.____-________.___ __.__ 70-71
Sampling methods...
.
. 4,6,70
Sandstone, defined....- __ _ __ ___. ...._
6
Savage, T. E., and Button, A. H., quoted. __-___-___ __-__
18
Scope of study..
3
Scour channels, significance__ . .
- 59-60,61
Section, Chattanooga shale..
_ .__ _ 24,27,37,38,63,64,74
Flynn Creek cryptoexplosive feature.._10
Maury formation.. ___.___________-_ __ 24,27,37,38,63,64,74
Swan Creek area... __..
-.. ...
15
Sediment, age....
.
54
compaction.
. . .
. ... ...
55
rate of accumulation.. . .
.
...
_ _ 54-55
relation of black shale to gray claystone__.._....._.__ 55-56
sources....
31,52-53transportation- . ... ... ......__ ... __..__
54
Sequatchie Valley, anticline__ _... ....._______________ 9, pi. 4
location.....
. .... 3,7,8,72
presence of bentonite_ . .. __ .._...__________
31
uranium in Chattanooga shale...____....._.._._.___________
76
Shale, defined.____ ___ __-____________________ 5-6
Shallow water, indications for origin of shale..
.
60-62
meaning of term.
. . . _..._
57
Siltstone, defined. .
. . __..__ ..________
6
Southern Highland Rim. See Highland Rim.
Spores..
19,43,46, pi. 5
Standard locality and section, Chattanooga shale.
23,24
Maury formation.
. , _. _._.. __ 63,64, pi. 16
Standards, potentially exploitable on shale,...
69
Stockdale, P. B., age of Chattanooga shale_.
. _ 18,19
quoted...
.
.
. __..__.__ 18,58
Strahl, E. O., and others, cited_... ___________ _____
46
Stratigraphy, Chattanooga shale. ..
21-40
regional__. ... .....
. __._ 8-9
Structure of area_._ _ ___.______ ________ 9-12, pi. 4
Sub-Chattanooga residuum.... . __ __ _______ 14-16, pi. 5
Sulfuricacid_ . _ __ .__________________
70

Button, A. H., and Savage, T. E., quoted..
Swan Creek area, "blue phosphate"section_..
.
Swartz, J. H., age of Chattanooga shale...

18
25,28,47
15
18

T
Tasmanites......................_.._
Terminology...
.
Tourmaline__
Transportation of sediment.
Trask, P. D., quoted.
Troost, Gerard, history of name of formation-..
Trousdale shale...______.____ -__Twenhofel, W. H., quoted .
U
Ulrich, E. O., age of Chattanooga shale...
Uranium, determination.-.-.
early studies
origin and distribution .
regional variations in content
relation of thickness of shale to content-_
sampling_
tonnage__
U.S. Bureau of Mines, analyses and assays
drilling..

19, pi. 5
5-6
48
54
59
12
-_. 19,22-23,28,48
58

..

17
71
3-4
71-75
75-76, pis. 11,12
..
71
70-71
76
47, pi. 17... 5,71,72,73" Varved" bed, middle unit of Gassaway member. 39-40, 45, 55, pi. 13
Varves, absent in Chattanooga shale_.
. .
55
Vitrain, analyses_~ _ ~_ ___. _47
identified_.
19
W
Water currents, transportation of sediments.
54
Wells Creek cryptoexplosive feature..
10
Western Highland Rim. See Highland Rim.
Whetstone Branch formation.
. . __ 18,42,45,58
Wind, transportation of sediment.. .
.
54
Wolf Creek Reservoir, covers area of outcrops. _.... __.__
4
Zircon.

O