DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE, Secretary 

UNITED STATES GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, Director 

Professional Paper 108-H 

THE PLIOCENE HISTORY ()F NORTHERN - ' 

AND CENTRAL MIS~3ISSIPPI 

BY 

EUGENE WESLEY SHAW 

Published February 15, 1918 

Shorter contributions to general geolo~'y, 1917 

(Pages 125-163) 

WASHINGTON 

GOVERNMENT PRINTJN,G OFFICE 

1918. 

CONTENTS. 

Page. 

Introduction. . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 

or~elation of deposits and surface featur~s of lower and upper parts of Miss ssippi basin .. . ....... ____ ....... . 125 

Sedrmentary record ............................... _ . .................... . ........... -__ .... _ .. _ .. _ . _ . . . . . 126 

General character of pre-Pliocene formations ....... _ ... ~ .... ;_ ..... ;._ ..................... ___ ... _.~... 126 

Identification of pre-Pliocene formations ....... _ ..... . __ .... __ .... __ ............... __ .. __ · ___ .... _..... 127 

"Lafayette formation" ........... ____ . . . ... __ .................... __ ~ _ .............. . .... ___ . . . .. . .. . 128 

Gener~l nature ......................... _ ...... . ............ . .......... __ . . . . . . . . . . . . . . . . . . . . . . . . . 128 

Interpretations .......... _ ... _ . _ ..... . ... . _ ........... . . . .. _ ..... . . ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 _ 

Basis of various interpretations ..... _ ... ___ .. .. .. . . .. .. .. . . .. . . . . . .. .. . .. .. .. .. .. . . .. .. . . . .. . . . . .. 131 

Terrace deposits correlated with the Oitrone1le formation.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 

Location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 

Number arid names ............. ~ ... · ..................... . . .. ....... ~ . ·. . . . . . . . . . . . . . . . . . . . . . . . . . . 134 

Constitution .......... . .................................................................. ". . . . . . . 134 

Hollow pebbles ~f iron oxide ....................... . .... _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 

Stratification .................................. · ....... . .......... ~ ... -........ .. ................. 138 

Stratigraphic relations...................................... .. .................................... 139 

Fossils ................................................... . . . ...... . . _-__ ......................... 139 

Age and correlation ....................... . ................ . ...................... : . . . . . . . . . . . . . . 139 

Upl~~~:~:~nma:~~:~~i~~l~~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ i~~ Temporary definitions ........ . ......... . ............................................ -.............. 141 

Possibility that some record of Pliocene time may be left in the colluvium or residuum .... _ . . . . . . . . . . 142 

Colluvium .... _ •...... _._.~ ................. -....................... : ......... ·.......... . .......... .142 

General nature ................. .. ......... .................................................. 142 

Pebbles and boulders ......................................................... ............. 142 

Distribution and lithology ........................................ --....... _ .. -... . ..... _.... 142 

Source ........ ~ ....................................... .. __ .. . ....................... . ..... - 143 

History ................................. . .... -. _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 

Past cycles .......................... . _ ... ·..... . .. .. ......................... . . . . . . . . . 143 

Present cycle .. ........... . .... . ................. _ ........................ ~ . . . . . . . . . 144 

Residuum .................. . ............... . ...... . ............................ ~ ............. ·... 146 

General nature."--- ... . ..... -........... _-. .. ............ . .. _ .............. ~................... ·146 

Iron content .................... . . -. .. . . . . . ..... . .......... _................ . ................. 146 

:Bearing on Pliocene history of region ...... _ ............... , .................. _ . .. . . . . . .. . . . .. . · 148 

Physiographic record .......... . . .. ................... . ... . ..................................... . ... ,...... 148 

Nature of data ...... . ..... . . . . . .... . .. . .......... . ..... ·_ ................ . ............ _ . . . . . . . . . . . . . . . _148 

General surface configuration of the region ...................... : . ......... _ .......... .. ~ . • . . .. . . . . . . . .. 149 

Uplands ....................... . ......... . .. . . ·. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 

Monadnocks .............................................. . ................................. ·. . . . . 149 

Evenness and concol'dance in height of lower crests....................................... . ........ 150 

Relation of physiographic features to those of the Appalachian province............................ 151 

General character of surface along border...................................................... 151 

Highland· Rim peneplain... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . 152 

Coosa peneplain .. . ........... . ...... . ................ . . . ............. .. . ·..................... 153 

Warping of peneplains ................ . . . ....... : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 

Terraces ..........•..... --. . .......... . .. . ................ ~ .. _, ...................................... 154 -_ 

General features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 -

Brookhaven terrace ....... . ... . .......... . ......... . .... . .... ~ ............... -. . . . . . . . . . . . . . . . . . . . 155 

Sardis terrace... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 -

Canton terrace ............. · ............ . ..... . .. . ................. . ............................ ~ 156 

Loxley terrace .............................. . ............ . ................................ , ..... - 156 

Warping of terraces ....................................... ~ ........ . ........ _ ............ ~ . . . . . . . . 156 

III 
IV CONTENTS. 

Physiographic record-Continued. Page. 

Drainage modifications .... · ........... ·....•....... ........................ ..... ..•................... 156 

Mississippi River................................................................................. 156 

Pearl River ...................................... ~ .............. ·.· ......... ~.................. .... 157 

Big Black River ...................................... _.: .... .. ................................ 158 

Tom big bee River .............................................. ·. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 

Structural record ....................... · ........ ................... .. ........ ...... '. . . . . . . . . . . . . . . . . . . . . . . 160 

Conclusions ...................................................................... · .................... ·_ . . . 160 

Interpretation of the "Lafayette formation'' .................. ..... .... ~ ........... ~................... 160 

Diastrophism .....••••••................. : ................ ... ................................ ~ . . . . . . . 161 

Position of surface at beginning of epoch ............................................ :. . . . . . . . . . . . . 161 

Deformation .••.•••••••••...................................... ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 

Erosion ...................•.••....... ............................. : .................. ; . . . . . . . . . . . . . . 161 

Weathering and local transportation..... . ..... . ... . ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 

Through transportation and corrasion.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 

Drainage modifications .•........................ , ........................................... ~ . . . 162 

Sedimentation.:. . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 

Sedimentation in valleys· ................... ' ............... : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 

Coastal sedimentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 

Climate and life of the epoch .................. . ............ :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 

ILLUSTRATIONS. 

PLATE XLV. Generalized east-west and north-south sections of Mississippi. ............................... . 

XLVI. Stratification and general appearance of massive, cross-bedded, and laminated material 

formerly included in the "Lafayette formation," now interpreted as belonging with various 

formations underlying Mississippi. ................................................... ~ ... . 

XLVII. Stratification an'd general appearance of material formerly regarded ·as "Lafayette formation','' 

at and near type locality, now regarded as belonging to the Wilcox group ............. . 

XLVIII. Stratification and general appearance of Pliocene and eu.rly Pleistocene terrace deposits, most 

of which have been classified as " Lafayette formation" ................................. . 

XLIX. Stratigraphic relations of Pliocene terrace deposits .......................................... . 

L. Hollow pebbles of iron oxide (Klappersteine), possibly produced by replacement of limestone 

pebbles ........... · ...................................................................... . 

LI. Uneven bedding and gravelly portions of Pliocene terrace deposits .............••............ 

LII. Typical exposures of colluvium ............................................................ . 

LIII. Exposu,res suggestive oi origin of colluvium ................................•. _ .............. . 

LIV. Recently formed deposits of known origin and history, somewhat resembling the older colluvium but still differing rather markedly. ~ ........................ ~ .......... ~ .. ' ......... · 

LV. Remarkable pocket-like features, suggesting filled burrows or potholes, and ' pebbles and 

· boulders of quartz and quartzite from colluvium ........... · ..................•......... ~ .. . 

LVI. Residuum or material in place but modified somewhat by .;eathering, though little if any part 

has been removed ..................................................................... . 

LVII. Views illustrating reddening and probable concentration of iron compounds near the surface .. 

LVIII. Profiles along Illinois Central Railroad from Grand Junction, Tenn., through Jackson to Martinsville, Miss., and from a point near Memphis, Tenn., to Grenada, Miss .......••....••.... 

LIX. Views illustrating occurrence and mode of .development and the excellent exposures afforded 

by old field gullies ......................................... . ·· .................. · ........ . 

LX. Vie~s illustrating peneplains and monadnockS ................................ ~ ............. . 

FIGURE 21. Diagram showing general nature and areal arrangement of materials underlying the surficial deposits 

of . Mississippi .............................................................. ~ ............. . 

22. Diagram showing the slope of the Cretaceous peneplain, according to Hayes and Campbell, and the 

slope of the Paleozoic floor beneath the Cretaceous deposits of Mississippi, which has been· considered as b~ing equivalent to this peneplain ..................... , ......................... . 

23. Diagrammatic profile to show relations of upland surface features of Mississippi to the peneplains 

in a portion of Tennessee to the northeast ........................ ~ .......................... . 

24. Diagrammatic cross section of flio ene deposits and profile of Pliocene terraces in the south end of 

Mississippi ............................... · ........ ~. · .... ' ................................. 

25. Sketch map showing shapes of drainage basins in Mississippi ................•.................• 

Page. 

126 

132 

132 

132 

133 

138 

139 

142 

142 

142 

143 

146 

147 

148 

148 

149 

127 

150 

151 

155 

:L59 
• 

THE PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPPI.1 . 

By EUGENE WESLEY SHAW. 

INTRODUCTION. 

The record of Pliocene time in northern and 

central Mississippi is generally assumed to 

he scant or lacking. The published geologic 

maps of this region show no Pliocene formations, and the only deposit in the region that 

has been assigned to the Pliocen~ is the unmapped . so-called Lafayette formation. This 

formation, however, in recent years has lost 

some of its good standing, for several students 

. have become convinced that the material constituting the "Lafayette" in Mississippi has 

been altogether misinterpreted, most of it being simply more or less weathered material belonging to various underlying formations. 

Heretofore no stratigraphic record of early and 

middle Pliocene time and no physiographic 

record of any part of this epoch have been recognized in this region, and hence if recent views 

concerning the "Lafayette," commonly regarded as late Pliocene, are correct, knowledge 

of Pliocene events in this part of the State is 

very scant indeed .. However, recent work on 

the later Tertiary and Quaternary geology of 

the Mississippi embayment has brought to 

light an unexpected amount of data bearing on 

the Pliocene history of Mississippi, and the object of the present paper is to present some of 

these data in preliminary form and to point out 

their apparent significance. They pertain not 

only to the deposits of the region but also to 

the surface features. Space is not available for 

more than an outline of the basis of the conclu::. 

sions set forth, and the life of the epoch is 

barely mentioned. 

. The field work upon which this report is 

based was done in the years 1912 to 1916, inclusive, and is a part of a general study of the 

1 In its basis of field work and in its conclusions this paper is closely 

related to a recent paper by G. C. Matson, entitled "The Pliocene Citronelle formation of the Gulf Coastal Plain" (U. S. Geol. Survey Prof. 

Paper 98, pp. 187-192, 1916. The writers of the two papers visited 

critical points in the field together and compared their data and conclusions. 

Mississippi embayment planned and arranged 

for by T. Wayland Vaughan, chief of the section of Coastal Plain inv-estigations of the 

United .States Geological Surv-ey. For sev-eral 

years before 1912 the writer had been studying 

the surficial geology of the upper part of the 

Mississippi basin, and thus,.although the report 

deals primarily with only a portion of Mississippi, it is based upon a general study of both 

the upper and lower parts of the Mississippi 

basin. It has been the writer's good fortune 

to see also deposits and surface features more 

or less closely related to those under discussion 

in other parts of the Atlantic and Gulf Coastal 

Plain, including eastern Mexico. In the field 

work in Mississippi he had the advantage of 

frequent consultation with Dr. E. N. Lowe, 

State geologist. · 

CORRELATION OF DEPOSITS AND SURFACE 

FEATURES OF LOWER AND UPPER PARTS OF 

MISSISSIPPI BASIN. 

One of the principal objects of the study of 

the embayment area was the correlation of the 

late Tertiary and Quaternary deposits and 

physiographic features of the Mississippi embayment and Gulf coast with those of the 

upper par.t of the Mississippi basin. The need 

for such correlation has long been felt. For 

example, concerning the field work of R. D. 

Salisbury in 1889 T. C. Chamberlin 2 says: · 

The especial object of this investigation was to determine the relationships between the valley deposits of the 

lower Mississippi and the glacial. deposits of the upper 

, Mississippi. By examining these deposits at the supposed 

po,int of their junctions with the border of northern drift 

it is hoped to demonstrably establish their time ratios 

and their genesis. 

The elev-enth and twelfth annual reports of 

the Surv-ey contain similar statements as to 

Prof. Salisbury's work. No area offered greater 

promise for valuable results, for here extensive 

2 U. S. Geol. Survey Tenth Ann. Rept., pt. 1, p. 129, 1890. 

125 
126 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. 

Coastal Plain deposits of late Tertiary and loess of the upper part: of the Mississippi basin _ 

Quaternary. age were believed to be contiguous has been traced almost continuously to that 

to if indeed not actually interstrati:fied with of the lower part, a:rid apparently there are at _ 

glacial deposits, and a -great trunk stream, least two other deposits :of :loess in both areas, 

along which terraces and .other alluvial de- one older and one younger, but both Pleistoposits might be -expected flows from . one cene. (2) Two low stream ~erraces, one probpart of the area to the other. In New Jer- ably Illinoian and the other Wisconsin, may 

sey, how~ver, deposits of the two classes be traced from the north into the Mississippi 

were found to be more c~osely connected, . embayment, where both dip . down to the 

though no large stream flows from the deposits present flood plain of the Mississippi. No 

of one class to those of the other. As a matter· record of early Pleistocene ~ime (Kansas ~r 

of fact, north of Cairo, ill., there is. a gap of Nebraskan) has yet · been found adjacent to. 

about .40 Inil.es between glacial . and Coastal or n~ar. the upper .end of the Mississippi embay-· 

Plain deposits, and in this gap the Mississippi ment. . (3) Certain rather . extensive gravel 

flows through a rather narrow gorge in which deposits along the lower Mississippi are believed -

there are practically no terrace deposits, so that to be terrace deposits of 'Pliocene age and are 

it is almost impossible to determine the rela- correlated with most of the scattered patches 

tion of any Quaternary formation of the upper of gravel in the upper part of the Mississippi 

part of the Mississippi basin to any of 'the lower basin. 

part~ . The loess deposits of the two areas, 

however, can be correlated with a considerable 

degree of certainty. 

Along the lower Wabash and Ohio not only 

the loess but also two or three low terrace deposits form a practically continuous connection 

between the ·coastal Plairi. and glacial forma.:. 

tions. On both the southeast and southwest 

borders of Illinois there are scattered patches 

of gravel that have been called Lafayette and 

are commonly regarded as late Tertiary. If, 

as the writer believes, they ~re of late Tertiary 

age, they should be of some use in correlating 

the formations' of the two areas. In southwestern Indiana, however, small areas of such 

gravel have been referred provisionally to the 

Eocene, 1 because of their position on a plain 

thought to be Eocene. . 

Although the correlation of formations and 

surface features of the upper and lower parts · 

of the Mississippi basin is thus. difficult and 

somewhat unsatisfactory, nevertheless" certain 

significant facts have been ascertained and 

certain inferences are more or less probable. 

Some conclusions by the author and others 

regarding pre-Pliocene and also Quaternary 

geology and physiography are included in this 

,paper, f<?r upon them · depends in part the 

identification of '· the Pliocene deposits and 

. surface features of Mississippi. The conclusions having to do ·with Quaternary geology 

!l!ay be __ ~u:rnmarize~ as follows: (1) The main 

t Fuller, M. L., 'and Clapp, F. G., U.S. Geol. Survey Geol. Atlas, 

· Patoka folio (No. 105), 1904. 

SEDIMENTARY RECORD • . 

The sedimentary record of Pliocene time in 

northern and central Mississippi is believed by 

the writer ~o consist principally of a part of 

the materials that have been included in the 

"Lafayette forlliation." This formation has 

heretofore been regarded as the only record of 

Pliocene time in this region, but some revision 

in the interpretation of. material referred to 

it is suggested in . the following · pages. In 

order to give a clear idea of the basis on which 

the previous inferences concerning this formation rest, it is necess~ry to describe briefly . the 

the nature of the underlying formations. 

GENERAL CHARACTER OF PRE-PLIOCENE FORMATIONS. 

The general distribution of the materials· underlying central and northern Mississippi is indicated in fig~e 21. From this map it is to be 

seen that these portions of the State .are under- . 

lain by formations ranging in ag~· from , 

Devonian to Oligocene, and that a large part 

of the area is · underlain by Eocene strata. 

No Pliocene strata are shown, the "Lafayette" 

D;lantle not being_ mapped. Most of the formations shown .consist, like the "Lafayette," 

largely of irregularly bedded silty sands, but 

a _ few . consist of limestone or clay. ·The 

individual formationshave been identi~ed and 

traced principally by means of ·their fossil 

content, lithologic character, and stratigraphic 

relations, but their fossil content is commonly meager, their lithologic character IS 

• 
U. 9. GEOL.OQICAL SURVEY 

N. 

A 

1,ooo N. 

HIGH LA -----------------

-1.000 

B 

N 0 

s 

A 

B 

H A v E N p L 

Centers of middle Pliocene upl ifts ? 

B' 

I I - 5•;;, e ~.oo uu(} 

0 10 I!> 7.0 

N 

<U 

c: Ill Vo 

uu o., 

.. ~ t 

· ... -~-:--=- . -- -:------- -

Center of latest 

~5 .)0 MI L(; 

•.• --- ..1 ----

SARDIS PLAIN ? 

c A 

PAOFE8810NAL. PAf'ER 10 PLAT£ XLV 

Feet 

1,000 

500 

0 

-soo 

s. 

-1,000 

8 

s. 1,000 

500 

0 

-500 

GENERALIZED EAST-WEST ~NO NORTH-SOUTH SECTIONS OF MISSISSIPPI, EACH REPRESENTING DIAGRAMMATICALLY THE GENERAL FORM OF THE SU RFACE AND NATURE OF THE UNDERLYING ROCKS IN A BEL.T 80 OR 40 MIL.ES WIDE. 

A. EAST-WEST SECTION THROUGH OXFORD. 

Near the east end the I ine of the section bends to the northeast. The dip of the paleozoic rocks is not k nown with certainty, but appare ntl y its directio n is southwest, though presumabl y not at t he same rate as that of the coastal plai n deposits. 

B AND B'. NORTH-SOUTH SECTION REPRESENTING A BELT THROUGH THE CENTRAL PART OF THE STATE INCLUDING OXFORD AND JACKSON. 

S hows the effect of pliocene(?) uplifts in t he south . cen tral pa rt of the state whi ch carr ied pli ocene gravels to a ompa rative ly 1reat alt itL1de. 
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPPI. 127 

extremely varied, and their stratigraphic relations are somewhat difficult to determine. 

All three lines of evidence taken together are 

so commonly inconclusive that opinions differ 

as to the identity of some of the most accessible 

strata-those lying near the surface, abundantly exposed, and known as Lafayette. 

Some have inferred that most of the beds 

lying close to the surface belong in this surficial 

formation, which is described as differing 

markedly in many respects from the underlying formations; others, particularly more -recent workers, have thought that the concept 

of a blanket formation is incorrect and that 

most of the sands and other materials so 

classified belong in fact with the several 

underlying formatjons. Indeed, as shown in· 

Plate XLV, most of the "Lafayette" of Mississippi is found where ·the underlying beds 

are very sandy. 

IDENTIFICATION OF PRE-PLIOCENE FORMATIONS. 

The confusion concerning the "Lafayette" 

appears, to be due partly to the lack of diagnostic features in that_ formation itself and 

partly to the irregular distribution of such 

features in underlying formations. Concerning the older rocks, the testimony of fossils 

is in many places incontrovertible. Remains 

of land pi_ants are fairly common in some 

formations and sea shells in others, but nevertheless the mass of material whose age can be 

directly determined from fossils is a small 

fraction of that involved in this discussion. 

In many exposures fossils are not to be found, 

and in many others only certain beds can be 

classified with certainty by means of fossils. 

The lithologic character of only a few of 

the formations is sufficiently distinctive to be 

areas or by comparing stratigraphic relations. 

It is therefore difficult to identify much of the 

material that liesfar from beds of known age. 

Thus Tertiary and Cretaceous strata that 

aggregate thousands of feet in thickness and 

crop out over an area· of thousands of square 

miles.include few layers sufficiently persistent 

and identifiable to be traced far with certainty 

as to their exact stratigraphic positions. Yet 

these strata were long ago divided into forma25E3::::z=3:::==:E25=:==3:so'=====:i75E======SJoo M i I es 

usable in identification and mapping. The FIGURE 21.-Diagram showing general nature and areal arrangement of 

Selma chalk is easily recognized by both its materials underlying the surficial deposits of Mississippi. 

lithologic character and its fossil content, but 

most of the formations in this region and also 

in much surrounding territory in the Coastal 

Plain are made up largely of irregularly stratified sand and silt which include very few beds 

that are identifiable by their lithologic character. 

Many of the individual pre-Pliocene strata 

are not persistent and hence can not be 

correlated by continuous tracing over wide 

100833°--18----2 

tions, concerning whose general positions and 

areas of outcrop there can be no doubt, notwithstanding the fact that there is a lack of 

agreement as to whether the most accessible 

strata in the region-those immediately underlying the surface and abundantly exposed in 

cuts and washes-belong with the underlying 

strata or constitute, as has been thought for 

many years, a distinct surficial formation. 

In the opinion of the writer and others much 
128 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, ·1911. 

if not most of the material in central and 

northern Mississippi which has been called 

Lafayette or Orange sand belongs in fact with 

the underlying formations and differs from 

them only in being on the whole more reddened 

and otherwise weathered. The very fact, 

however, that ·such an idea, though tenable, 

has been so slow in arising is expressive of the 

difficulty in identifying and tracing the beds. 

"LAFAYETTE FORMATION." 1 

GENERAL NATURE. 

The ''Lafayette formation" as heretofore 

described 2 is a late Pliocene or early Pleistocene mantle deposit which crops out throughout most of the Coastal Plain of eastern North 

America and some adjoining territory, an 

area of more than 200,000 square miles. It 

consists largely of more or less deeply ironstained gravel, sand, clay, and loam, the upper 

part generally massive and the lower stratified. 

In thickness it ranges from 1 foot to 200 feet or 

more. Fossils are generally rare, and those 

that have been found are regarded as out 

of place and range. in age from Devonian to 

Pleistocene, inclusive. As described, ·the formation shows little detailed or consistent relation to altitude, -topography, physiography, 

or geologic features. However, though it 

. rests upon rocks of all ages, from pre-Cambrian to late Tertiary, it is scantily developed 

in tb.e high country of Paleozoic' and older 

rocks bordering the Coastal Plain. Its surface and base are . roughly parallel to the 

present surface, and it underlies uplands, hill-

~ides, and terraces alike. Other Coastal Plain 

formations have roughly concentric areas of 

outcrop, the youngest being nearest the sea, _ 

but this one mantles all the others. 

INTERPRETATIONS. 

The interpretations of the "Lafayette formation," though showing more or less variety, 

fall into four principal classes; the first assumes that it was deposited by flood water 

. from Pleistocene glaciers; the second, that it 

was laid do~ during a marine submergence 

1 A more complete discussion of the status of the "Lafayette formation" is in preparation. · 

2 See particularly the description by Hilgard (Geology and agriculture 

of Mississippi, 1860) and McGee (U . S. Geol. Survey Twelfth Ann. Rept., 

pt. 1, pp. 347-521, 1891). ' 

of the Coastal Plain; the third, that it is the 

product of a less catastrophic process of stream 

deposition induced by broad uplifts of the 

Appalachians; and the fourth, that much if 

not most of it is a more or less weathered portion of the older and underlying formations 

of the region, a part of it being made up of 

material of other kinds. 

Although :Bartram,3 the Rogerses/ Booth,5 

Conrad, 6 :Mather/ Lyell, 8 and Tuomey 9 had 

done some work on similar deposits along the 

Atlantic coast, and Wailes/0 Safford, 11 and Harper 12 in Tennessee and Mississippi, Tuomey 13 

seems to have been the first to attempt an extended interpretation of the "Lafayette" of 

the Gulf coast. He called it the "Southern 

Drift" and correlated it with the glacial.deposits of northern United States. Wailes had 

called it" "Diluvium or Northern Drift" without attempting an explanation, and Safford 

and Harper had called it "Orange sand." 

It should -be remarked that there has been a 

lack of complete harmony as to what should be 

included in the formation. Modifications have 

been made at different tim.es in the 80 years of 

work upon it, so that although "Southern 

drift," "Orange sand," and "Lafayette fonnation" have in a general way a similar significance, they differ somewhat in meaning from 

time to time and from author to author . 

Safford, 11 who introduced the term "Orange 

sand," applied it not only to what later becan1e 

McGee's Lafayette and Columbia, but also to 

deposits of Wilcox age (Eocene), and he classis Bartram; William, Travels through North and South Carolina, 

Georgia, east and west Florida, pp. 28-30,1791. 

t Rogers, W. B., Report of the geological reconnaissance of the State. 

of Virginia, p ; 13, Virginia Board Pub. Works, Phila,delphia, 1836. 

Rogers, H. D., Report on the geological survey of New Jersey, 2d ed., 

p. 17, 1836. 

• Booth, J. C., Memoirs of the geological survey of the State of Delaware, pp. 94, 97, 1841. · 

6 Conrad, T . A., Observations on a portion of the Atlantic Tertiary 

region; Nat. Inst. Proc., vol. 1, p. 177, 1842. 

1 Mather, W. W ., Geology of New York, pt. 1, pp. 246, 261-268, 274-

275, 1843. \ 

s Lyell, Charles, jr., On the newer deposits of the Southern States of 

North America: London Geol. Soc. Quart. Jour., vol. 2, pp·. 405-406, 1846; 

A second visit to the United States, vol. 1, pp. 344-346, vol. 2, pp. 242-

266, 1849. 

9 Tuomey, M., Geology of South Carolina, pp. 186, 188, 212, 1848 . 

10 Wailes, B. L. C., Report on the agriculture and geology of Mississippi, pp. 245-253, 1854. · ) 

u Safford, J. M., A geological reconnaissance of Tennessee: Tennessee 

Geol. Survey First Bienn. Rept., pp. 148, 162, 1856. ' 

12 Harper, L., Preliminary report on the geology and agriculture of 

Mississippi, p. 162, 1857. · 

1a Tuomey, M ., Second biennial report on the geology of Alabama, p. 

146, 1858 (transmitted for publication in 1855). 
PLIOCENE HISTOR.Y . OF NOR.THER.N AND CENTRAL MISSISSIPPI. 129 

fied both as Cretaceous. Crider,! on the other 

hand, excluded much that· had been included 

by McGee, saying: 

He [McGee] likewise included in the term Lafayette 200 

feet or more of the Wilcox which belongs to the Eocene. 

* * · * The term as used in this [Crider's J report is 

restricted to the thin veneering of iron-stained pebbles and 

sand which overlaps unconformably all the other formations of the State, from the older Paleozoic rocks along 

Ten~essee River to and including the Grand Gulf group of 

the late Miocene. * * * The thickness of the formation varies from a knife-edge to 50 feet. 

Yet McGee 2 states that ''It · is sepai·ated 

from all of the underlying formations by a noteworthy unconformity." 

It seems remarkable that there should be 

such certainty about the existence of a thing 

and such difference of opinion as ,to its whereabouts. The disagreements as to the location 

of the great unconformity at the base of the 

forn1ation suggest the query whether it may not 

after all be at the top-in other words, whether 

there is any Lafayette. 

The writer and others of the section of the 

Coastal Plain investigations of the United 

States Geological Survey have traced a part of 

even Crider's restricted Lafavette into older 

formations and suspect that · very large part 

must be so reclassified. For example, the ex-

' tensive gravel deposits that are well exposed in 

the pits east of Iuka, regarded by Crider as 

Lafayette, have been found by L. W. Stephenson and the writer independently to pass beneath Cretaceous formations at Iuka. 

Hilgard,3 the chief student of the "Lafayette" in Mississippi, agreed with Tuomey in his 

interpretations of the "Southern drift," saying 

"His [Tuomey's] suggestions regarding the 

nature and origin of the water whieh deposited 

the Orange sand [or 'Southern drift'] forrnation appear to be confirn1ed by · all the additional observations subsequently made by 

myself." He says further: 

However different may be the geological detail of the 

Orange sand formation from that of the Northern d.rift 

deposits, the evident analogy of their lithological composition and general history would lead us to suppose the two 

formations to be genetically related. In both cases immense volumes of water destitute, or nearly so, of organic 

life rushed southward, bearing with them the fragments 

and detritus of the older formations. * * * 

lCrider, A. F., Geology and mineral resources of Mississippi: U.s. Geol. Survey Bull. 283, p. 45, 1906. 

2 McGee, W J, The Lafayette formation: U. S. Geol. Survey Twelfth 

Ann. Rept., pt. 1, p. 497, 1891. 

a Hilgard, E. W ., op. cit., pp. 27-28. 

Whether or not the Orange sand deposits contain any 

material necessarily derived from a high northern latitude 

still remains to be determined, for thus fat the materials for 

comparison are imperfect on both sides. By far the greater 

mass of the pebbles occurring · in Mississippi appear to 

be referable to sources lying south of the Ohio River on 

either side of the Mississippi, while the rocks most common 

in the drift of Illinois-granite, mica schist, and metamorphi_c sandstone are either very rare or (like granite) entirely 

wanting. 

Thirty-two years later Hilgard published an- " 

other paper 4

- on the "Lafaye_tte" in whieh he 

says that the formation was laid down by running and violently agitated waters at a time of 

high elevation, partieularly of the northern 

United States, and says that much erosion 

preceded and followed its; deposition. 

The hypotheses concerning the "Lafayette" 

may be summariz~d as follows: in the order in 

which they have been advanced and peeome 

more or less popular: (1) It was laid down by 

glacial floods; (2) it is a sea deposit made during 

rapid submergence; (3) it is a stream deposit; 

and (4) it is not a formation at all but a hodgepodge of parts of various formations. Parts 

of it have also from time to time been ex-

-cluded because of their identification with 

other formations. But there have been many 

departures from this general trend. For example, Crider 5 as late as 1906 says that the 

quartz pebbles are "doubtles·s the fragments 

of the great northern drift carried southward 

by great volumes of cold fresh ~a ter at the. 

elose of the glacial epoch," thus not only subseribing to the glacial hypothesis but dating 

the formation at the end of that epoeh, whereas 

most workers, have eonsidered it much more 

ancient. The end of Pleistocene time was 

probably not more than a tenth and perhaps 

not more than a twentieth or thirtieth as long 

ago as the beginning. 

The second interpretation, that of deposition by sea water, was best set forth by McGee. 

By its excellence of logic and presentation of 

evidence his paper brought the name Lafayette into general use and crystallized ideas 

eoncerning its extent and interpretation. McGee's views are suggested by the following 

quotation: 6 

The record of Lafayette deposition is one of oceanic 

invasion, not of catastrophic swiftness, yet of such rapidity 

4 Hilgard, E. W ., The age and origin of the Lafayette formation: Am. 

Jour. Sci., 3d ser., vol. 43, pp. 389-402,1892. · 

5 Crider, A. F., op. cit., p. 45. 

6 McGee, W J, op. cit., p. 508. 
130 SHORTER CONTRIBUT'IONS TO GENERAL GEOLOGY, 1917. 

that the waves rolled over the sinking hills without carving 

shore lines; without even building broad beach~s such as 

the modern keys of the southern coast; and the inunda:-

tion was not stayed until it reached inland, drowning the 

southeastern margins of the continent in a zone 100 to 500 

miles wide. * * -*. The waves and currents spread 

* * * · [the sediment] here and there along the newmade coast, mixing it with the materials gathered from the 

new-made sea bottom. In this way only could have .been 

accumulated the widespread Lafayette mantle, composed 

chiefly of residua · of slow rock decomp<?sition and subordinately of material from local formations, together 

with great gravel beds about the waterways. * * * 

In age the Lafayette formation is many times older than 

the earliest known Pleistocene deposit, and much newer 

than any other well-defined formation of the Coastal 

. Plain. 

The third interpre~ation, that the "Lafayette" is a stream deposit, is well set forth 

by Chamberlin and-Salisbury/ who say: 

It is assumed that the [Plio~ene] upward bowing (of 

the Appalachian province] was felt first in a relatively 

narrow belt along the predetermined axis, that thle rise 

was gradual, and that the rising arch increased in breadth 

as it rose. 

The result wa.s renewed erosion and increase 

of load of the streams, and this load was too 

great for them to carry across the Coastal · 

Plain to . the sea. As the uplift progressed the 

deposit was spread farther and farther toward 

the sea. Hill and Vaughan 2 plac~ a somewhat similar interpretation on the Uvalde 

formation, which they say is of the same age 

as the "Lafayette," though they do not assume 

a broadening area of uplift and a consequent 

gradual seaward shifting of gravel. They 

say: "It does not appear to the writers that 

it is necessary to postulate a marine submergence or an absolutely horizontal deposition 

level," and they describe the deposit as occurring on the seaward side of the Balcones 

sca.rp, suggesting as conditioning agents (1) 

cloudburst storms in an ·arid or semiarid 

· region and (2) gradual uplift of the area on 

the landward side. 

It will be noted that the "Orange sand" or 

"Lafayette" is regarded as ·Cretaceous by 

Safford (1856), as Pliocene by McGee (1891) 

and by Chamberlin. and Salisbury (1906), 

and as Pleistocene by Tuomey (1855), Smith 

t Chamberlin; T. C._, and Salisbury, R. D., Geology, vol. 3, Earth 

history, pp. 305-306, 1906. 

2 Hill, R. T ., and Vaughan, T. W ., Geology of the Edwards Plateau 

and the Rio Grande Plain adjacent to Austin and San Antomo, Tex.: 

U.S. Geol. Survey Eighteenth Ann. ~ept., pt. 2, p. 246, 1898. 

and HHgard (diff~rent dates), and Crider 

(1906). ' 

The fourth interpretation of the "Lafayette" 

-that at least part of it is in reality more or 

less weathered and slumped .portions of under-

.lying formations-may be illustrated by the 

following quotations from McGee, Vaughan, 

and Berry. 

McGee 3 says: "It should be noted that a 

part of the deposits designated Orange sand 

by different geologists consists of rearranged 

residuary debris of the Tuscaloosa and perhaps 

other formations." 

Vaughan 4 argues that the "Lafayette" 

aromid Mount Lebanon and Arcadia, La., _ is 

residual and states the grounds for his belief 

as follows: (1) In it are found "fossils as casts 

in ferruginous sandstones or as ferruginous 

replacements," and these fossils are the same 

as those in the underlying formation; (2) "the 

transition from the Eocene to the superficial 

deposits can be traced"; (3) "there are in the 

specimens from the superficial deposits no 

indications of their having been waterworn." 

Berry 5 says: 

-In the exposures at Oxford the deposits are a unit with 

every graduation from unweathered materials below to 

oxidized and more or less ferruginous sands above. · Now here in this region is there a lin~ of unconformity or a 

pebble be~ to mark the supposed time interval extending 

from the early Eocene to the Pliocene. The change in 

color of the materials, when marked at all, is at varying 

levels and is due apparently to the depth to which the 

ferric oxide in the sands has been dehydrated.-

A distinct variety of this interpretation worthy o{ mention has been set forth by Harris,6 

who believes that the "Lafayette" is made up of 

parts . of various formations but that those 

parts differed originally from other parts of the 

same formations. He says:. "It has been my 

belief for several years 'that whenever the 

shingle of an old shore has -been preserved, 

there will be found 'Orange sand,' be the age 

of such littoral beds Mesozoic or Cenozoic," 

and he postu)ates a gradual seaward shifting 

of the deposits during emergence of the land. 

a McGee, W. J., Three formations of the middle Atlantic slope: Am. 

Jour. Sci., 3d ser., vol. 35, p. 330,"1888. 

4 Vaughan, T. W ., The stratigraphy of northwestern Louisiana: Am. 

Geologist, vol. 15, p. 219, April, 1895. 

• Berry, E. w ., The age of the type exposures of the Laf~yette formation: Jour. Geology, vol. 19, p. 251, April-May, 1911. 

·6 Harris, G. D., The geoiogy of the Mississippi embayment with special reference to the State of Louisiana: Louisiana Geol. Survey, pt. 6, 

p. 33, 1902. 
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPPI. 131 

BASIS OF VARIOUS INTERPRETATIONS. 

The question naturally arises, Why should 

there be so much difference of opinion concerning the content and interpretation of the "Lafayette"~ Surely it is not because the' material has failed to receive sufficient attention ' for many able investigators have given long 

study to it in the field, and many others have 

written and theorized about it. Again, it is 

not because the formation is inaccessible for it . . ' 

hes at or near the surface and is abundantly 

exposed throughout a populous region covering 

hundreds of thousands of square miles. Why 

then should ideas concerning it differ so much 

more widely than those concerning other formations~ · 

In the first place the formation is generally 

described as being unique, both in development and in constitution, differing more or less 

markedly from any other ancient or modern 

deposit, and hence there are few opportunities 

for making enlightening comparisons. Second, 

although many investigators regard it as a 

unit having a persistent and recognizable character for example, McGee 1 says that "as a 

whole_ the formation maintains so distinctive 

and strongly individualized characteristics as to 

be readily recognized wherever seen * * * 

it is more uniform petrographically than any 

other formation of even one-fourth of its extent"; and E. A. Smith 2 says that "the Lafayette has a character * * * _ so well 

marked that the observer with any reasonable 

degree of experience will scarcely ever rerriain 

long in doubt as to its identity," yet, as McGee 

himself says, "this distinctive aspect of the 

formation is to some extent fortuitous." If it 

consisted of any single or any small group of 

diagnostic characteristics there would be less 

room for doubt. The difficulty arises out of 

the fact that it consists of a large group of features, several of which may be found together 

in another formation. . 

In correlating other deposits fossils are often 

use_d, bu~ the ''Lafayette," l!nder all interpretatiOns, Is regarded as having no index fossils. 

Fossils are often found in material that had 

been regarded as Lafayette, but it is always 

inferred either that they are out of place, having 

come from some older formation, or that the 

I McGee, W J, op. cit., p. 489. 2 Smith, E. A., Am. Assoc. Adv. Sci. Proc., vol. 55, p. 374, 1906. 

stratum containing them and all below it 

should be reclassified and put into the underlying fo~mation, for, remarkable as it mayseem, 

the fossils that are certainly in place are always 

found to be just such as occur in the formation 

which happens to lie just below. Under the 

fourth interpretation the ''Lafayette" thus 

becomes a combination of the nonfossiliferous 

autcropping portions of several formations. 

Stratigraphic relations should be of some 

use in identifying the "Lafayette," ·for it is 

described as being everywhere unconformable 

at the top and bottom, as resting upon rocks 

o~ all ages older than Quaternary, and as lying 

either at the surface or just below some oth~r 

surficial deposit. But throughout three-fourths 

if not nine-tenths of the region under discussion 

the unconformities can not be found or their 

location agreed upon. The remainil).g tenth 

or. fourth is the area of the terrace-deposit 

phase of the "Lafayette" described below. 

. Stratification seems to be one of the prinCipal features used in the -identification of the 

''Lafayette," the bedding of which is commonly, 

especially in the _area under discussion, extremely irregular, often being described as 

jumbled. But irregular bedding is also found 

in older formations, where it is of the same 

general type in so far as bedding so varied can 

be said to follow a general type of irregularity. 

Lithology is of some value in identifying the 

"Lafayette," which lacks limestone and certain other kinds of rock, though it consists of 

materials so diverse as clay, shale, sand, sand:.. 

stone, gravel, conglomerate, and iron ore. But 

the usefulness of lithology for this purpose is 

reduced by the fact that other formations in 

the region are lithologically similar to the 

''Lafayette," though perhaps none others show 

so great diversity. 

Other criteria are often useful in correlationcolor, physiographic expression, mode of weathering, etc.-and some of these are involved in 

the differentiation of the "Lafayette," but 

apparently no one of them is sufficient. Ratner 

its identification seems to rest on an aggregate 

of many features, of which any one or even 

several may be found in some other formation. 

Some single features, however-for example, 

the common extreme irregularity of bedding, 

with clay m~sses in. sand-have generally been 

believed to be somewhat more characteristic of' 
132 SHORTER CONTRIBUT'IONS TO GENERAL GEOLOGY, 1917. 

the "Lafayette" than of other formations. 

The writer and others regard these irregularities 

in bedding · as characteristic of many Coastal 

Phtin formations and believe that material near 

the surface does not differ in this respect from 

that farther down and that parts of the "Lafayette" are terrace deposits. (See PlP.XLVIXLIX.) . 

In brief, the basis upon which the first three 

interpretations of the "'Lafayette formation" 

set forth above have rested is about as follows: 

First, throughout central and northern Mississippi and also mos't other parts of the Coastal 

Plain of the eastern United States, to which all 

but a very small fraction of the material called 

Lafayette is confined, the material within 20 

to 100 feet of the surface is redder than that 

below, no matter to what formation the lower 

material belongs. Second, the material from 

1 to 15 or 20 feet below the surface is commonly 

more faintly stratified and many believe it to 

be more irregularly stratified than that below. 

Third, in some places the material within a 

few feet of the surface contains elements not 

found in the underlying formations and is set 

off from them by a rather sharply defined plane, 

being apparently susceptible of the interpretation that it consists of the remnants of terrace 

deposits. 

Under the fourth interpretation it is contended that much of the "Lafayette" differs 

from underlying formations only in being, on 

the whole, redder, except that close to the surface the stratification is fainter or disturbed and 

the color in many places changed to brown or 

buff. Thesefeatures are believed to be much 

more reasonably regarded as products of the 

, weathering and slumping of the underlying 

sandy and silty formations, both at the time of 

their deposition and later than as characteristic 

of a single formation, especially because (1) the 

constitution of the material seems to depend 

·everywhere on the constitution of the underlying formation; (2) there is.generally no sharp 

lower limit to the redness and irregular or jumbled bedding, and, on the whole, the faintness 

of the stratification decreases downward; (3) 

notwithstanding the general irregul,arity of bedding and lack of persistent strata and fossils in 

the pre-Pliocene formations strata called "Lafayette" can here and there be traced continu.:. 

ously in to strata belonging unquestionably to an 

underlying formation. Moreover, characteristic 

fossils of the underlying formation, particularly 

impressions of plant leaves, have been found 

by Lowe, 1 Berry, 1 and others in lenses of soft 

clay, s.ome of which are extensive and evenly 

laminated, and . therefore could not possibly 

have 'Qeen taken bodily from some older formation and incorporated in the "~afayette." It 

is regarded as a significant fact that the fossils 

from the "Lafayette formation" described as 

transported and redeposited are either silicified 

Pal~ozoic fossils in hard pebbles or are characteristic of the particular formation which happens to underlie the "Lafayette" at the place 

of their occurrence. 

TERRACE DEPOSITS CORRELATED WITH THE 

CITRONELLE FORMATION. 

LOCATION. 

In discussing the constitution of the·" Lafayette," Hilgard 2 says: 

There are within the State two distinct regions of occurrence in which this material [gravel] appears in force. 

One of these e~tends along the eastern edge of the alluvium 

of the Mississippi River, occupying, in northern Mississippi, parts of the counties of D~ Soto, Panola, Yalobusha, 

Carroll, Holmes, and Yazoo, gradually diminishing as the 

territory of the fossiliferous Eocene is approached and giving out almost entirely in the greater portion of Warren 

County. Then, below Vicksburg, it extends inland in a 

southeast direction and is found in numerous cuts on 

theN ew Orleans, Jackson & Great Northern Railroad down 

to the Louisiana line. 

The other region of occurrence of the pebble bed begins 

at the north on the Tennessee River, in East Tishomingo, and extends along the waters of Big Bear Creek to 

the. eastern head of the Tombigbee, reaching the latter 

str~am by way of Hurricane and Bull Mountain creeks, in 

Itawamba County. It then extends southward on the 

eastern side of the Tombigbee and is continued into Alabama, meeting the great pebble beds of the Warrior, which 

bear the city of Tuscaloosa. · 

Further study ha$ confirmed the generaliza- . 

tio:r~ that most of the gravel of the "Lafayette" 

borders· the largest streams. In Mississippi it 

is found (1) in a belt of ~oull.ties adjoining the 

Mississippi bottoms and .extending from Memphis to Vicksburg, where the belt broadens and 

swings east across the State, and (2) in the 

northeastern counties of the State and a belt 

extending southward along the Tombigbee. 

The question naturally arises: Is it not possible 

that the gravel has been misinterpreted and 

that it is in part Cretaceous and Tertiary, be1 Unpublished notes. 

2 Hilgard,E. W., Report on the geology and agriculture of Mississippi, 

pp. q-12, 1860. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XLVI 

A. B. 

c. D. 

E. F. 

G. H. 

STRATIFICATION AND GENERAL APPEARANCE OF MASSIVE, CROSS-BEDDED, AND LAMINATED MATERIAL 

FORMERLY INCLUDED IN THE "LAFAYETTE FORMATION,", NOW INTERPRETED AS BELONGING WITH 

VARIOUS FORMATIONS UNDERLYING MISSISSIPPI. 

A, Thin wavy-bedded silty sand with embedded fragments of iron-cemented sandstone 5 miles east of Batesville. B, lndisti nctly cross-bedded gravel 5 miles southeast of I u ka. C, Cross-bedded sand, shale, and pebbles of Eutaw formation half a mile south of luka. D, Indistinctly cross-bedded sand of Eutaw formation(?), with clay pebbles and streaks, 1 mile east of 

luka; altitude600 feet. E, Cross-bedded silty sand of Wilcox group at Baileys Spring, 1 mile southeast of square, Oxford. 

F, Massive purple clay of Wilcox group in bottom of lsom Ravine, Oxford. G, Thin, hard, evenly bedded white sandy 

clay 6! miles southeast of Oxford. H, Doubly cross-bedded sand of Wilcox group half a mile north of Oxford. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XLVII 

A. B. 

c. D. 

E. F. 

G. H. 

STRATIFICATION AND GENERAL APPEARANCE OF MATERIAL FORMERLY REGARDED AS "LAFAYETTE 

FORMATION" AT AND NEAR OXFORD, THE TYPE LOCALITY, NOW REGARDED AS BELONGING TO 

THE WILCOX GROUP. 

A, Uneven interfingering beds of clay and sand t~ree-fourths of a. mile north of Oxford. B1 "Jumbled" clay balls and 

lenses 4 miles west of Oxford. C, Intraformational unconform1ty between strat1f1ed redd1sh sand and wh1te clay half a mile east of Oxford. D , Somewhat indistinct, uneven interfingering beds of clay and sand three-fourths of ·a mile north of Oxford. E, Heavy beds of sand and clay 3 miles west of Oxford. F, Sharpl y defined interfingering 

beds of white clay and red sand 1 mile north of Oxford. G, Peculiar stratification of silty sand on east side of 

Fourmile Creek 2 miles east of Oxford. H, Irregular stratification of sand 1 mile south of Oxford. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XL VIII 

A. n. 

c. D. 

E. F. 

G. H. 

STRATIFICATION AND GENERAL APPEARANCE OF PLIOCENE AND EARLY PLEISTOCENE TERRACE DEPOSITS, 

MOST OF WHICH HAVE BEEN CLASSIFIED AS "LAFAYETTE FORMATION." 

The strata seem to range generally from 5 to 10 feet in thickness and to be comparatively persistent and yet lenticular, and these 

seem to be diagnostic features. A, 3t miles east of Bates ville, M1ss. B, 3 miles east of Batesville, Miss. C, 6t miles 

southeast of Oxford , Miss. D, 3~ miles east of Batesville, Miss. E, Part of type exposure of Port Hudson formation at Port 

Hickey, La., probabl y early Pleistocene but shows same general form of stratification as Pliocene terrace deposits. F, West 

end of main part of petrified forest 3 miles southwest of Flora, Miss. G, Detail from E, illustrating buttress form of 

weathering common in sandy clay deposited by Mississippi River. H, 8z miles west of Grenada, Miss. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XLIX 

B. 

A. 

D. 

F. 

E. G. 

STRATIGRAPHIC RELATIONS OF PLIOCENE TERRACE DEPOSITS. 

A, Terrace deposit resting on strata of Wilcox group and overlain by 2 feet of loess 4! miles east of Batesville, Miss. 

B, Terrace deposit resting on strata of Wilcox group and overlain by 2 feet of loess 5 miles northeast of Sardis, 

Miss. C, Reworked terrace gravel on deformed and eroded edges of Tuscaloosa formation, Cottondale, Ala. 

D, Eastern edge of terrace deposit resting on strata of Wi I cox group and overlain by loess 2! miles north of Batesville, Miss. E, Terrace deposit overlain by loess, with well-preserved old soil between, 15 miles east of Yazoo 

City, Miss. F, Terrace deposit overlain by loess 1! miles south of Edwards, Miss.; apparent gradation from one 

to the other probably due to creep. G, Terrace daposit, perhaps somewhat shifted and reworked, resting on Tuscaloosa formation, Tuscaloosa, Ala. 
PLIOCENE HISTOHY OF . NOHTHEHN AND CENTHAL MISSISSIPPI. 133 

longing in underlying formations, and in pa:rt a -

terrace deposit or a series of terrace deposits 

along the Mississippi and Tombigbee and. perhaps other streams, thus differing markedly 

from and having little relation to the "Lafayette'' of most of the broad regions between 

these rivers~ The gravel exposed in the pits 

east of Iuka, for example, is evidently neither a 

Quaternary terrace deposit nor a mantle formation corresponding to descriptions of the 

H Lafayette," for it dips under Cretaceous strata 

and belongs in that system, as was inferred by 

L. C. Johnson 1 as long ago as 1887. Other gravels have been found to belong at other places in 

the Cretaceous and Tertiary systems. 

The attempt to answer_ this question was 

begun by making a traverse westward from 

Oxford, Miss., in company with the State 

geologist, Dr. E. N. Lowe. The gravel area 

·was entered about 9 miles east of Ba,tesville. 

West of this point not only the deposits but 

also the surf ace features differ more or less 

markedly from those to the east, although the 

general altitude is not much lower. As discussed more fully under ''Physiographic :record," the principal difference · in surface features is that to the east there are no extensive 

flat upland areas, whereas to the west the 

slightly lower interstream areas are commonly 

flat-topped, and from many points it is evident that several have almost exactly the same 

height, though different groups have different 

heights, suggesting several terraces. 

Similar examinations were then made west 

of Holly Springs and near Grenada, Durant, 

Canton, Jackson, Vicksburg, Natchez, and 

Fort Adams, Miss., and St. Francisville and 

Baton Rouge, La. The same gravels were 

followed eastward across the State to the 

great deposits at Weathersby, Montrose, and 

other places, which Matson 2 has in~luded in 

the Citronelle formation. The gravels in 

Tishomingo County, in the northeast corner 

of the State, and those along the Tombigbee 

and its branches, particularly in and near 

Greene County, Ala., were then examined. In 

some districts the evidence that the deposits 

are remnants of terraces is so strong as to be 

thoroughly convincing. Elsewhere, especially 

1 Smith, E. A., and Johnson, L. C., Tertiary and Cretaceous strata 

of the Tuscaloosa, Tombigbee, and Alabama rivers: U.S. Geol. Survey 

Bull. 43, pp. 115-116, 1887. 

2 Matson, G. C., The Pliocene Citronelle formation of the Gulf Coastal 

Plain: U. S. Geol. Survey Prof. Paper 98, pl. 38, 1916. 

where the underlying rocks are limestone or 

clay, as near the junction of the Warrior and 

Tombigbee, the gravel remnants are small, far 

apart, and discordant in height. In the 

writer's opinion the discordance is due to the 

facts that the deposits are remnants of several 

terraces which stood at different heights, and 

that the underlying materials have suffered 

more or less erosion· while they were capped 

with considerable bodies of . gravel, which 

have thus been le~ down, with more or less 

lateral shifting. Some of the gravel, how-

.ever, belongs in Cretaceous and Tertiary formations. 

Although the terrace deposits are somewhat 

difficult to recognize, because they are not 

well preserved and because only a very small 

fraction of the region of their occurrencethe western part of Mississippi-has been 

topographically mapped, sufficient data have 

been gathered to rarrant the conclusion that 

some of the material formerly included in the 

"Lafayette formation" is in reality several 

terrace deposits. These deposits differ markedly from the "Lafayette" of most of t~e 

area under discussion, in being dissimilar to 

the underlying formations, in containing elements that could not have been derived from 

the weathering of those formations, in hav'ing 

a sharp lower limit, _and in lying at concordant 

altitudes. To illustrate, nearly aU the material called Lafayette :formation in . Lafayette 

County, Miss., the type locality, falls in that 

part now interpreted as belonging in the underlying formation. It consists of reddish silty 

sand and clay, such as could readily have been 

formed by the weathering of the underlying 

Wilcox deposits, and it grades downward into 

those deposits. But in Panola County, immediately to the west, there are extensive 

deposits of gravel lying at concordant and 

somewhat lower altitudes and having sharply 

defined bases. These deposits could not have· 

been produced by the weathering of the 

underlying forma~ion and are evidently terrace 

deposits of the Mississippi Valley. Some of 

them have been so profoundly eroded that 

they are now scarcely recognizable as terraces, 

but their terrace origin is shown by the facts 

that the eroded remnants are, so far as determined, of concordant heights, that the material 

is rather sharply distinct from the other material formerly referred to the Lafayette but 
134 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. 

now regarded as belonging with the underlying formations, and that they occupy a belt 

along the side of the Mississippi Valley. · 

NUMBER AND NAMES. 

The reasons for believing that the terracedeposit portion of the "Lafayette'! represents 

several distinct terraces are largely found in 

differences in altitude, which are discussed 

under "Physiographic record." No reasons 

for subdivision have yet been found in the 

nature of the materials, and apparently differences in degree of weathering or dissection are 

not sufficiently marked to .be usable as criteria. 

The deposits along the Mississippi seem to lie at 

four different heights above the river bottom, 

and it is inferred that they are remnants of four 

terraces. In addition, there are also two or 

more lower terraces which are assigned to the 

Pleistocene, and these are considerably less 

gravelly. Exact and reliable determinations 

·of altitude are scarce, however, as the deposits 

have been worn down and dissected considerably, and much gravel has crept or been washed 

down over the slopes of the valleys that streams 

have sunk into them. Hence infe:r:ences concerning the number of terrace deposits are uncertain and will probably remain so for many 

years, though the number of principal developments may. be determined. In order to make 

reference'to them easier, it has seemed desirable 

to name the ·four apparently well-developed' 

terrace deposits, and Mr. Matson 1 and the 

·writer have agreed to call them Brookhaven, 

Sardis, Canton, and Loxley, in order from oldest 

to you:p.gest, each deposit being · extensively 

d~veloped and well preserved yet abundantly 

exposed at or near the place for which it is 

named. Brookhaven is in the southern part 

of Mississippi, 60 miles east of Natchez; Sardis 

is in the northern part, 50 miles south of 

Memphis; Canton is in the southern part, 25 

miles north of Jackson; and Loxley is in Bald"" 

win County, southern Alabama. 

CONSTITUTION. 

AltJ::wugh the terrace deposits are such as are 

ordinarily called gravel, the bulk of the material 

is sand through which pebbles are irregularly 

distributed. In some places the pebbles are 

contiguous, but they are rarely fitted so closely 

I Matson~ G.-C., The Pliocene Citronelle formation of the Gulf Coastal 

Plain: U.S. Geol. Survey Prof. Paper 98, p. 180, 1916. . 

together that the interstitial sand and clay_ is 

reduced to a minimum. · Generally the pebbles 

occur in irregular and poorly defined _lenses 

having a· wide range in size. In many places 

pebbles are scarce and the, material is more: or 

less clayey. The terrace deposits are comparatively poorly sorted, as illustrated by the following mechanical analyses. 

Sample 1 was taken from the Sardis terrace 

5 miles ·east of Batesville, and sample 2 from the 

Canton terrace 3 miles west of Canton. Each 

sample weighed about a pound and was· taken 

·from what seemed to be a single layer lying 

about 8 feet below the surface. The percentages of the coarser constituents were determined with wire screens.; of the finer, with a 

microscope. 

Mechanical analyses of samples of Pliocene terrace materials 

from Mississippi. 

Size of grains in millimeters. 

16. 000 -11. 312 .. : ............... 11.312 - 8. 000 .. ~ ............... 

8. 000 - 5. 656 ... .. .. . .......... 

5. 656 - 4. 000 .. ' .......... ~ .... 4. 000 - 2. 828 .................. 

2. 828 - 2. 000 ................. : 

2.000 - 1. 414 .... . ............. 

1. 414 - 1. 000 ......... . ........ 1.000 - . 707 .......... . ....... 

. 707 - . 500. · ... . . . ...... . .... 

. 500 - . 3535 ................. 

. 3535 - . 250. ________ ________ .

1 

. 250 - . 177 ......... . .... · . .. .. 

. 177 - .125 .......... . .... ·_ .. 

. 125 - . 0884 .. . ............. . 

. 0884 - . 0625 ............... -- . 0625 - . 0442 ... -.-.-. -.- ... -- . 0442 - . 0312 ..... -.- . . . -... -- . 0312 - .0221.---------------- . 0221 - . 0156 ..... . .... --. : . .. . 0156 - . 0110 ... -... . .... -.... . 0110 - . 00781 .... - . - -.. -·_ . - - - . 00781- . 00552 .......... - . _· - - -

. 00552- . 00391. . -........ - . -_ -· . 

. 00391.:... ~ 0027 6 .· ..... -... - - - - - - . 00276- . 00195 ......... - - - - - , . .00195 .............. . .. . ....... 

Approxima~e 

percentage. 

1 2 

0. 1 

.1 

.3 

. 5 

1 

1. 5 

2 

2. 5 

3 

3 

3 

3.5 

6 

8 

13 

11 

11 

7.5 

6.5 

5 

4 

2. 5 

1. 5 

1 

.5 

.3 

.2 

98. 5 

I 

0 

0 

0 

0 

. 1 

.1 

. 3 

. 5 

.5 

1 

1 

1 

2 

2 

3 

4 

6 

8 

8.5 

10 

11 -

9 

9 

8 

-6 

5 

3 

99 

Samples of various surficial materials from 

Mississippi were sent to the Bureau of Soils, 

United States Department of Agriculture, with 

the request that they be analyzed according to 

the standardized method of that bureau. The 

results are valuable for c·omparative studies of 

terrace deposits and other surficial n1aterials. 
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISS!ISeiPPI. 

Analyses of "surficial rnaterials frorn Mississippi. 

[Made by Bureau of Soils, U.S. :Cept. Agr.] 

Medium Fine Very fine sand sand sand 

(0.5 to (0.25 to (0.1 to 

o.25 o:1 0 05 

Locality. 

Fine Coarse 

gra'rel sand 

(2 t) 1 (1 to 0.5 

milli- milliSilt 

(0.05 to 

0.005 

milli- milli- milli: · meters). meter). t ) t ) milli- meter). me er . me er . meter). 

32 

38 

1 

724 

Recent alluviurn. 

Mississippi River silt from bank of canal 

3 miles northwest of Vicksburg, Miss .. Mississippi River silt from foot of bluff, 

Natchez, Miss ...... , .............. ·1 

Alluvium of Tennessee River at Riverton, Ala ....... " ................... . Composite of 20 specimens of_ surface 

soil from Delay, Miss ............... . . 

Pleistocene alluviurn. 

41 Second bottom loam at west end of 

wagon bridge, Tuscaloosa, Ala ..... _ . 36 Clay from thin lamina iq. upper part of 

Natchez formation, Natchez, Miss .... 37 Sand from thin lamina at top of Natchez 

formation, Natchez, Miss ........ ... . 54 ·Pseudoloess 4 inches below the surface, 

941 

942 

943 

944 

945 

946 

725 

727 

731 

732 

734 

26 

29 

34 

35 

39 

40 

49 

50 

51 

half a mile east of Kokomo, Miss ..... . 

True loess. 

Loess 2 feet below surface near Ed wards, 

Miss ..•..... ----- ..... ---- .. ------- Loess 4 feet below surface near Ed wards, 

Miss ........ -----.----------------- Loess 5! feet below surface near Edwards, Miss ...................... . Loess 5! feet below surface near Ed- . wards, Miss ............ _ . _ ........ . 

Loess 6 feet below surface near Ed wards, 

Miss .............................. . 

''Brown loam" 2 feet below surface near Ed wards, Miss ............. ·_ ....... . 

Loess 6 feet below surface 1 mile southwest of Flora, Miss ........... _ . _ . _ .. _ 

Loess 20 feet below surface at south edge 

of Natchez, Miss. (contains fragments 

of shells) ................. _ . _ .. _ ... . 

Loess 8 to 10 feet below surface at Yazoo 

City, Miss. (contains fragments of 

shells) ............................. . Loess 12 feet below surface at Yazoo City, 

Miss. (contains fragments of shells) .. Loess 30 feet below surface at Yazoo City, 

Miss ........ ----- ... --------------- Loess 4 feet below surface 31 miles west 

of Grenada, Miss ................... . Basal! inch of loess at Yazoo City, Miss. 

''Brown loam" near Ed wards, Miss ... .. 

Loess or ''brown loam" 4 feet below sur- face 2 miles east of Chichester, near Edwards, Miss ..................... . Fossil-bearing loess, Natchez, Miss., 

from the loess clinging to several hundred fossils (contains fragments of 

shells) ............................ . Loess 2 feet above base of formation at 

Natchez, Miss. (contains fragments of 

shells) .........................•••• Loess 3 miles east-southeast of Yazoo 

City, Miss ................ " ..... .. Loess ( ?) 10! miles east of Yazoo City, 

Miss .... -----------------··------- Loess 15 miles west-southwest of Canton, 

Miss.' .................... ..•••...• 

100833°--18-3 

0.0 

.0 

. 6 

. 6 

. 0 

• 0 

. 0 

. 0 

• 0 

.0 

• 0 

.0 

. 0 

. 0 

. 0 

.1 

. 3 

.1 

.0 

. 0 

. 0 

. 0 

.0 

. 7 

.1 

.0 

.0 

.0 

-- --1 

0.0 

.3 

1.9 

1.5 

.0 

. 0 

. 3 

• 6 

• 0 

.0 

.1 

. 0 

.0 

.1 

. 0 

.1 

.4 

.1 

. 0 

.0 

.5 

.0 

.0 

1.2 

.1 

.0 

.0 

.0 

0.0 

.2 

4. 2 

.4 

.1 

.1 

1.0 

;2. 5 

.1 

• 0 

.1 

.1 

.1 

. 2 

. 0 

.0 

.1 

. 0 

.1 

. 0 

.3 

.0 

.1 

.9 

.1 

.0 

.0 

.o 

0. 1 

. 6 

39. 1 

2.6 

2.1 

3.2 

19. 1 

48.0 

.2 

. 0 

.3 

. 2 

.2 

.3 

. 2 

. 2 

. 2 

.2 

.2 

.5 

1.2 

.2 

.5 

4.9 

.2 

.3 

.4 

.4 

0. 6 

13.6 

15.9 

8.8 

4. 5 1 

12.8 

26. 7 

9. 6 

3.7 

4.2 

4.8 

4.6 

3.2 

1.5 

4.8 

5.6 

9.6 

6.2 

8.4 

10.4 

9.4 

5.9 

5.8 

10.8 

9.2 

5.5 

8.3 

6.0 

34.9 

49.1 

24.1 

62,8 

66.6 

46.8 

39.4 

30.6 

88.1 

82.0 

83.4 

83.9 

85.0 

84.0 

81. 6 

86.9 

83.3 

88.2 

87.2 1 

75.9 

80.3 

77.2 

81.5 

76.0 

83.2 

80.7 

74.0 

82.0 

Clay 

(0.005 

135 

to 0 Total. 

millimeter). 

65.1 

35.9 

14.8 

22.3 

26.2 

37.2 

13.5 

8.1 

8. 1 

13.4 

10.5 

11.9 . 

10.7 

14.8 

12.6 

6.3 

5.8 

4.2 

3.8 

12.6 

7. 7 

16.5 

11.6 

5.5 

7.1 

13. 1 

16.4 

10.9 

100. L 

99.7 

100.6 

99.9 

99.5 

100. 1 

100.0 

99.4 

100.2 

99.6 

99.2 

100.7 

99.2 

100.9 

99.2 

99.2 

99.7 

99.0 

99. 7 

99.4 

99.4 

99.8 

99.5 

100.0 

100.0 

99.6 

99.1 

99.3 
136 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. 

Analyses of surficial materials from Mississippi-Continued. 

Locality. 

Quasiloess. 

11 Upper 2 feet of ''brown loam '' 8 miles 

northwest of Oxford, Miss .......... . 13 ' 'Brown loam'' 18 inches below the sur- face 1 mile southwest of Oxford, Miss. 

15 ' ' Brown loam'' 2~ feet below the surface · 2 miles southeast of Oxford, Miss ..... 17 "Brown loam" 2 feet below surface } 

mile east of Oxford, Miss ........... . 

Mixed loess, colluvium, residuum, and 

terrace deposits. 

7 ''Brown loam'' from a groove cut from 

top to base in a vertical face in the 

head of a ravine 3 miles northwest of 

Oxford, Miss ...................... . 9 "Brown loam" from a groove cut from 

top to bottom (5 feet) in a vertical cliff 

8 miles northwest of Oxford, Miss ..... 16 '' Brown loam'' 2 feet below the surface 

at south edge of Oxford, Miss. (probably not true loess) ................ . 24 Mixed loess 10 feet below the surface 2} 

miles north of Batesville, Miss ..... . 43 Loess ( ?) 2 feet below surface of divide 3 

miles west of Holly Springs, Miss .... 46 Loess ( ?) 4 feet below the surface 1 mile 

south of Sardis, Miss .............. . 48 Loess ( ?) 16 miles west of Yazoo City, 

Miss ............................... · 726 Material down to 4 feet below surface 3 

miles west of Grenada, Miss ....... . 728 Material down to 2 feet below surface 1} 

miles south of Oxford, Miss ....... . 729 Material2 to 4 feet below surface (mostly 

colluvium), same locality as 728 ..... 

W asked loess. 

33 Loess or loess wash, Vicksburg, Miss ... 

Recent colluvium. 

12 "Wash creep"! mile south of station at 

Oxford, Miss. (composite of 20 small 

4 

10 

42 

30 

52 

5i3 

handfuls ......................... . 

Old colluvium. 

Sandy-silt containing pebbles ! mile 

west of station at Iuka, Miss. (composite of 20 small handfuls) ....... . ''Brown loam'' ( ?) from top of exposure 

below schoolhouse, at Oxford, Miss. 

(May belong just below ''brown 

loam ") ........................... . Washed loam 8 feet below the surface 

10 miles southeast of Corinth, Miss ... 

Pliocene sea-terrace deposits . . 

Clay conglomerate 6! miles east of Pinola, Miss ......................... . Lafayette (?) from groove 8 feet high, 6 

inches wide, and 1 inch deep, cut in 

cliff in gully in northeastern part of 

Brandon, Miss .................... . "Buttress clay," Woodville Miss .•.•.. 

Fine Coarse IMedi~ gravel san'd san (2 to 1 (1 to 0.5 <

0·

5 to 

"11" "11" 0.25 m1 1- m1 1- millimeters). meter). meter). 

0.0 

.0 

.0 

.0 

.0 

.0 

.0 

.2 

.0 

.0 

.0 

.0 

.0 

:5 

.0 

.4 

.0 

.0 

.0 

5.0 

2.0 

. 0 

1.9 

.2 

1.4 

.4 

.1 

.7 

.4 

3.6 

.2 

.0 

.1 

.1 

.4 

7.6 

.1 

4.9 

.4 

1.1 

5.0 

9.3 

31.0 

.1 

3.7 

.1 

1.8 

.4 

.. 2 

.7 

.5 

2.2 

.1 

.1 

.1 

.1 

.4 

5.9 

.1 

5. 7 

1.6 

1.7 

14.1 

7.2 

23.0 

.3 

Fine 

sand 

(0.25 to 

0.1 

millimeter). 

6.1 

.5 

4.5 

1. 7 

1.0 

2.5 

2.1 

1.8 

. 3 

.5 

.6 

.6 

1.8 

18.4 

.4 

17.6 

39.6 

5.4 

45.8 

18.7 

21.3 

65.5 

Very 

fine 

sand 

(0.1 to 

0.05 

millimeter). 

5.9 

4.0 

4.0 

5.5 

5.1 

. 7. 5 

6.6 

10.1 . 

3.0 

8.1 

10. 7 

4.3 

3.5 

5.1 

9.3 

9.4 

11.5 

5.4 

3.2 

16.8 

1.2 

3.4 

Silt 

(0.05 to 

0.005 

milli~ 

meter). 

69.1 

72;6 

71.4 

76.2 

Clay 

(0.005 

to 0 

millimeter). 

13.1 

22.6 

16.7 

15.0 

74.4 18.2 

72.0 16.4 

t 

72.1 18.1 

71. 9' 9. 2 

71.1 25.0 

7.3. 6 16.8 

65.0 23.3 

78. 1 16.2 

73.0 20.1 

44.9 16.9 

85.4 

50. 7 

20.0 

56.1 

24.8 

19.5 

1.4 

13.8 

4.8 

11.3 

27.0 

29. 3" 

6.8 

22.9 

19.7 

16.6 

Total. 

99.8 

100.0 

99.8 

99.2 

99.0 

99.8 

99.8 

99.0 

99. 7 

99.1 

99.8 

99.4 

99.2 

99.3 

100.1 

100.0 

100.1 

99.0 

99. 7 

99.4 

99.6 

99.7 
PLIOCENE HISTORY OF NO::tTHERN AND CENTRAL MISSISSIPPI. 137 

Analyses of surficial malt!rials from Mississippi-Continued. 

Q) Medium Fine Very 

'a Fine Coarse sand sand fine Silt Clay 

grave . sand sand (0.05 to (0.005 

~ Locality. (2 to:. (1 to 0.5 (0.5 to (0.25 to (0.1 to 0.005 to 0 Total. tll milli- milli- 0.25 0.1 0.05 milli- milli- ....... milli- milli- 0 meten). meter). milli- meter). meter). 

ci meter). meter). meter). z ---

Pliocene stream-terrace deposits. · 

27 Ancient stream silt (?) 10~ miles westsouthwest of Grenada, Miss. _________ OA 2.1 1.7 7.1 12.0 64.6 11.1 99.0 

28 Laminated loess or ancient stream silt 

30 feet below the surface at Yazoo 

City, :Miss ____ .. ______ . _ . ____ ....... .a 1.1 .5 1.4 11.2 79.9 5.6 100.0 

45 Loess (like silt) 6 feet below the surface 

7 miles southeast of Vidalia, Miss._ . .. • B 3.5 4.1 11.4 5.5 63.0 11.6 99A 

47 Terrace deposit ( ?) 6 miles north of 

Sardis, Miss ..... _ . _ . _ . _ . _ . _ ....... .0 .6 3.1 22.4 13.3 30.2 30. 1 99.7 

Residuum of Miocene deposits. 

31 Clay from Grand Gulf formation ! mile 

east of Pinola, Miss __ ..... _ ......... .0 .0 .0 .9 5. 1 65.8 27.5 99.:> 

Residuum of Eocene deposits. 

8 Wilcox or Lafayette formation 10 to 20 

feet below the surface ~ mile east of 

Oxford, Miss ... · .......... _ . _ . ___ . _ . 6.0 60.0 16.0 15.7 1.1 .8 .6 100.2 

14 Wilcox or Lafayette formation from thin 

sand lamina j mile north of station at 

Oxford, Miss._. __ .... _._. ___ ... ___ . .0 .0 .1 2.8 20.6 42.7 33.5 99. 7 

18 Clay lens in Wilcox formation 1~ miles 

south of Oxford, Miss. A layer of iron ore has been concentrated on top of clay .0 .0 .0 .1 2.8 58. 7 37.7 99.3 

19 Leaf-bearing clay at Oxford, Miss ..... .0 .0 .0 .4 12.9 48.4 37.7 99.4 

20 Wilcox or Lafayette formation 4 to 16 

feet below the surface 1~ miles south 

of Oxford, Miss . ....... _____ . _ .. _ . _ . .6 4.4 4.4 68.2 4.2 9.2 8.5 99.5 

21 Purple clay from Wilcox formation at 

Oxford, Miss ......... _ ........ . .... .0 1.0 2. 5 7.6 6.0 43.6 38.3 99.0 

22 Clay from Lafayette or Wilcox formation at schoolhouse, Oxford, Miss .... .0 .0 .0 .6 1.0 49.6 47.8 99.0 

23 Sand from Wilcox formation 10 to 20 

feet below the smface 1~ miles south 

of Oxford, Miss ..... _ ......... _ .. ___ .0 .4 1.5 81.9 5.4 5.8 4.2 99.2 

25 Sand from Wilcox formation 4 miles 

east of Grenada, Miss. This apparently iron-free sand is interbedded 

with iron-bearing sand. _ ....... _____ .0 .7 8.1 90.1 . . 5 .1 .0 99.5 

947 Residuum 3 feet below surface near Oxford, Miss ............ _ . __ -. -....... .2 2.4 6.0 29.0 7.0 41.7 14.6 100.9 

948 Residuum 6 feet below surface near Oxford, Miss ............ _ .. ~ .......... .0 .9 2.2 11.3 6.2 70.2 9.5 100.3 

Residuum of Cretaceous deposits. 

2 Clay balls in sand 6 feet below surface 1 

mile east of Iuka, Miss .... _ .. __ ._._. .0 .1 2.0 12.4 6.1 39.9 39.3 99.8 

3 Sand surrounding clay balls 6 feet 

below surface 1 mile east of I uka, Miss. .0 1.0 8.3 70.3 1.2 3.9 15. 7 100.4 

5 Sand 5 miles south of Iuka. Miss .. _____ ' .1 .6 1.0 48.0 31.0 10.1 8.9 99.7 

6 Sand containing small masses of white 

clay 4~ miles east-southeast of Iuka, 

6.0 1 

Miss. (Is the clay the residuum of 

limestone pebbles?) ............. __ .. .0 .1 1.3 60.0 7.2 25.5 100.1 
138 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, ·1917. 

The pebbles of the terrace deposits are mostly 

·of subangular chert, though well-rounded 

quartz pebbles are common. On the other 

hand, among the sand grains quartz predominates, and both quartz and chert are less well 

rounded. Quartzite, sandstone, and some other 

. rocks are represented among the pebbles, but 

limestone seems to be lacking throughout the 

·extent of the ·deposits. Many pebbles of all 

rocks, even quartz, are ready to fall to pieces so 

long have they been exposed to the weather .. 

The ·chert pebbles have evidently come from 

the areas of Paleozoic · rocks bordering the 

Mississippi embayment, particularly central 

Tennessee and Kentucky and the Ozark province, for many of them contain identifiable 

Paleozoic fossils. Most of the quartz pebbles 

may have come indirectly from the Piedmont 

province, which extends northeastward from 

northeastern Alabama, but _if so they probably 

started long .ago and in the meantime have 

been incorporated in one, if not several, Paleozoic and younger formations, for though very 

resistant they are well rounded and hence have 

been subjected to much wear, and no trans-

. porting agent is known to have carried materi.al 

from the Piedmont province to central and 

northern Mississippi since middl~ Tertiary 

time. The large streams have been flowing 

southward across this line instead of westward 

along it, and if the "Lafayette" is not the 

product of marine invasion no shore-line transportation has been operative along this course 

since Miocene, if indeed since Oligocene, time. 

On the whole, the lower part of each terrace 

deposit is more gravelly tha~ the upper part. 

In many places the upper fewfeet is sandy clay, 

free from pebbles, and separated rather sharply 

from the underlying more gravelly portion. 

Generally, however, the gravel lenses become 

smaller, less numerous, arid more sandy toward 

the top. 

As is common with the Coastal Plain formations, the terrace deposits are more or less deeply 

stained with iron and are here and there cemented into sandstone and conglomerate. 

HOLLOW PEBBLES OF IRON OXIDE. 

In some places-for example, near highwater mark in the bluff of the Mississippi at. 

N atchez_:.iron compounds seem to have partly 

replaced the .lime carbonate of limestone pebbles, for although here, . as elsewhere in the terrace deposits, limestone pebbles are lacking, 

there are many .hollow and fragile ·pebbles of 

iron oxide which contain a little clay. They 

are similar to some of the pebbles known as 

Klappersteine, aetites, or eagle sto_nes. (See 

Pl. L.) · These pebbles must have been more 

durable at the time of their transportation, for 

although t4ey have outwardly the form of pebbles they could not have been hollow when they 

were formed, else the shells of individual pebbles would vary -in thickness, many would be 

worn through, and fragments would be abundant. The clay in the interior appears to be 

indistinguishable from the residue of limestone 

after the lime carbonate has· been dissolved 

with acid, though both materials show considerable variation. . . 

The nature of the chemical processes involved 

in the replacement is not obvious. The facts 

(1) that in other regions layer:s of iron ore are 

common at the tops of such limestones as are. 

overlain by marcasitic shale, (2) that in many 

places the contact between iron ore and limestone does not lie along a bedding plane, its position indicating that the ore is not an original 

bed, and (3) that fossils consistjng partly of iron 

o~e and partly of limestone are :q.ot uncommon 

show that the replacement of lime carbonate by 

. some iron compound takes place rather readily 

under certain conditions that are common in 

nature. The fact that in some places the ore at 

such contacts is in the form of carbonate suggests .that ground water saturated with iron 

carbonate may on reaching . ~orne . lime carbonate effect replacement because of a greater solu.-

bility of the lime carbonate in water containing 

a moderate amount of carbon dioxide. 

STRATIFICATION. 

Although the Wilcox and other sandy 

Coastal Plain formations seem to show· every 

possible variety of stratification, the terrace 

deposits are commonly distinguishable from 

them by differences in stratification ·alone. 

The s&ata of the terrace deposits are comparatively thick and persistent, they are commonly separated from one another . by . a gradation layer several inches thick, and few of 

them can be followed more than half a mile 

because, as a rule, they pinch out or become 

indistinct. The contrast in stratification is 

well shown in Plates XLVI-XLIX and LI, 

·and its significance is b~lieved to be that the 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE L 

HOLLOW PEBBLES OF IRON OXIDE CKLAPPERSTEINE), POSSIBLY PRODUCED BY REPLACEMENT OF 

LIMESTONE PEBBLES. 

Each pebble contains a little clay, and some have a I ittle iron carbonate, suggesting that iron carbonate was the replacing 

compound and that it has since changed to the oxide. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE Ll 

B. 

A. c. 

D. 

E. F. 

UNEVEN BEDDING AND GRAVELLY PORTIONS OF PLIOCENE TERRACE DEPOSITS. 

A, Evenly stratified red gravel 2 miles north of Batesville, Miss. B, Uneven bedding planes 9 miles west of Holly 

Springs, Miss.; red (dark) material Wilcox group. C, Gravel in pit on campus at University, Ala. D, Undulating bedding plane with old soil 3 miles east of Batesville, Miss. E, Gravel and clay at Rocky Springs, 

Miss. F, Gravel resting upon Wilcox group 7! miles southeast of Byhalia, Miss. 
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPPI. 139 

terrace- deposits were made by a single large I it might have been taken from some older · 

s~ream, wher~as the Wilcox and other forma- formation and reburied in the terrace depostwns were laid down by many small streams. its. The writer, however, found some large 

STRATIGRAPHIC RELATIONS. 

The terrace deposits rest unconformably on 

rocks ranging in age from Cretaceous to Miocene or younger; In some places where the 

underlying formation is sandy and the terrace 

deposit not pebbly, it is difficult to recognize 

~he unconformity, but there can be no doubt of 

Its presence. Plate XLIX, A, B, D, G, shows 

the common appearance of the basal contact. 

The chief material overlying the terrace 

deposits is loess, which is thickest on the bluffs 

of the Mississippi and gradually thins to the 

east. It · also varies considerably along the 

bluffs, being 50 to 75 feet thick at Vicksburg 

and Natchez and scarcely half as thick west of 

Grenada. The contact at the base of the 

loess is _undoubtedly unconformable everywhere and is in places _marked by an ancient soil, as shown in Plate XLIX, E. However, as shown in Plate XLIX, F, in many 

places one formation seems to grade into the 

other. Most of this gradation is believed to 

be due to creep. At Natchez a thin layer of 

terrace gravel is overlain unconformably by a 

heavy deposit of river sand, which is apparently of early Pleistocene age; for it contains 

very deeply weathered pebbles from Canada. 

The formation which it represents has been 

so severely eroded that though a somewhat 

careful search has been made no other remnants 

of it have been found. -

The stratigraphic relations of the terrace 

deposits therefore indicate that they are considerably younger than any other Tertiary 

deposit of the region and considerably older 

than the loess and probably also than the 

early Pleistocene gravel at Natchez. 

FOSSILS. 

Diligent search for fossils that might aid 

in the determination of age and , in the 

_interpretation of the terrace deposits has 

been made by the writer and several others ' but almost none have been found. Silicified 

shells in pebbles are common but serve only 

to show that the material is post-Paleozoic. 

Petrified wood is not at all rare, but it has been 

considered of little · value in this study, for 

logs that could scarcely'have been reworkedthey are not only too large but are broken 

into sections which retain their natural position and orientation. Thin sections of some 

of this petrified wood have been cut and submitted to F. H. Knowlton, who says: 

One specimen is a conifer, probably Sequoia, and the 

other a 'dicotyledon, perhaps Querr:us. It is not possible 

t.o fix the age, though I think it is probably Tertiary, 

but beyond this I would not venture an opmion. -

AGE AND CORRELATION. 

The assignment of the terrace deposits to 

the Pliocene is based on the absence of igneous pebbles in them, their extremeiy weathered and dissected condition, their position 

topographically above the Natchez terracer 

which contains pebbles of glacial origin and is 

believed to be of early Pleistocene age, and 

the fact that they may be traced almost continuously into great deposits in the southern 

part of the State, some of which are unquestionably Pliocene.1 The terrace deposits are 

certainly younger than Oligocene, for they overlie formations of that age, and they are older 

than any of the loess, which is Pleistocene. 

Their appearance and relations indicate that 

they are much younger than the Oligocene formations and yet much older than the loess. 

UPLAND SURFICIAL MATERIALS. 

CLASSIFICATION AND TERMINOLOGY. 

For some purposes it is desirable to classify 

the material near the surface of the earth according to the extent and nature of its modification by weathering a~d other erosive 

processes. In the region under discussion 

the upland surficial deposits seem to fall naturally into the principal divisions named bel~w, 

from above downward. For convenience these 

will be called layers, though most of them 

have not been laid down as true strata. 

1. The surface soil, about a foot thick, containing more or less organic matter and other 

matte_r that has been modified by organic · 

agencies. 

2. A discontinuous but ubiquitous layer from 

1 foot to 15 feet or more in thickness, consistI Matson, G. C., op. cit. 
140 SHORTER CONTRIBUTIONS TO GENERAL _GEOLOGY, 1917. 

ing of material from the outcropping edges of landslides and creep and says that "colluvial 

underlying formations which has been washed soils form a large portion of rolling and hilly 

down slopes by sheet floods and small rills. uplands." On the whole, other authorities 

3. A layer from 1 foot to 4 or 5 feet thick, seem inclined to use the term in a broad sense 

consisting of surface portions of underlying more or less si-milar to Hilgard's usage, but 

formations which have crept a few or many most authors of geologic textbooks do not 

feet down slopes. Both Nos. 2 and 3 are as a use it at all. The adjective "pluvial" (from 

rule scarce or altogether lacking on the crests pluvius, rain) has been used for such deposits, 

of divides. but there is no corresponding noun, and, fur4. A layer of material in place, from 1 foot to thermore, rain ceases to be rain after it reaches 

5 feet in thickness and very deeply weathered. the surface of the earth. 

5. A much less but still deeply weathered Layer 3 is the result of a process for which the 

layer extending from No. 4 doWn. to the lowest ·word" creep'" is generally used, but there seems 

dry-season position of the ground-water sur-: ·to be no corresponding noun for the product. 

face. In other words, this division includes Layer 4, produced -by the weathering of 

all the material below No. 4 which is subject to underlying beds in place, might be called 

alternate wetting and drying and as a conse- residuum, but it is not exactly formed in place 

quence exhibits certain peculiarities, particu- by rock decay and left as a residue after the 

larly as regards its content of iron oxide. It ·leaching out of the more soluble products, for 

may be subdivided into two parts at the ordi- materials so extensively oxidized as those of 

nary position of ground water and ·is often most ·of the formations underlying . qplands in 

found at two horizons because of perched Mississippi can scarcely be said to decay 

ground water. . . further, and these materials consist generally of 

6. Below the dry-season ground-water table about equally insoluble substances-mainly 

the Coastal Plain strata are practically a unit quartz, clay substance, and iron oxide-and 

as regards weathering a~d consist largely of hence they are subject to little change in con- · · 

unconsolidated sand and clay many hundred stitution ·through the carrying away of more . 

feet thick, resting upon a floor of hard Paleo- soluble parts. Furthermore; layer 5, the 

zoic rocks. This division is scarcely surficial, layer between the subsoil ·and the groundand yet it seems to fall under the name regolith, water table, though differing in important 

which was proposed for unconsolidated sur- respects from layer 4, is almost as truly 

:ficial deposits. . residual. "Eluvium" also is not sufficiently 

The terms in use for surficial materials and definite and restricted. 

also those proposed but not yet current are The great mass of material below layer 5, 

only in part satisfactory for the materials comprising all the unc0nsolidated deposits 

listed above. . below the dry-season water table, is .somewhat 

Layer 1 is commonly called "soil," but many peculiar to areas of Cretaceous and Tertiary 

writers use this word in a broader sense to in- deposits in this and other parts of the yoastal 

dude this layer, the underlying subsoil, and Plain, for in few other places does a great thickvarying amounts of lower unconsolidated ness of largely unconsolidated material permaterial. petually saturated with water. rest upon a floor 

' For layer 2 the descriptive word "colluvial" of hard rock. For this material th~re seems to 

would be used by some geologists, but this be no distinctive name. It might be called 

term is an adjective and it has been used for "regolith," a name proposed by Merrill 3 for 

deposits of other kinds. Merrill 1 restricts it the"entire mantle of unconsolidated material" 

to "talus and cliff debris," a definition that resting upon "solid rock," but this term would 

would exclude layer 2. On the other hand, include all the other members in the list, for 

Hilgard 2 uses it in a much broader sense for though here and there ~he Coastal Plain strata 

the product of "rolling or sliding down, wash- are cemented they are on the whole comparaing of rains, sweeping of wind, etc." He does tively unconsolidated. 

not mention cliff debris, though he speaks of Other more or less generally current terms 

1 Merrill, G. P., A treatise on rocks, rock weathering, and soils, p. 319, 

1897; new ed., p. 307, 1906. 

2Hilgard, E. W., Soils, p.12, New York, 1906. 

·seem still less applicable to the surficial mate.,. 

s Merrill, G. P ., op. cit., new ed., p. 287. 
PLIOCENE HISTORY OF' NORTHERN AND CENTR.AL :i\HSSISSIPPI. 141 

rials in Mississippi and adjoining States than 

those already mentioned. ''Saprolite," proposed by Becker 1 for ''thoroughly decomposed 

earthy but untransported material," would include layers 4 and 5 and perhaps also a part of 

layers 6 and 1. As Merrill 2 remarks, it is also 

objectionable on other grounds. "Geest, " . 

proposed by Deluc 3 and indorsed by Eaton, 

Beck, McGee,4 and others, for decayed rock in 

place, as opposed to alluvium, has been used 

in a variety of senses, and in each it seems to include inore than one of the Mississippi deposits. "Local drift" 5 and "meteoric drift" 6 

would indicate layers 1 to 5 but were especially 

intended for residual material, for which the 

word "drift" seems inappropriate. 

TEMPORARY DEFINITIONS. 

Although most of the terms available seem 

objectionable on one score or another, it is undesirable to burden geologic literature with 

additional terms, at least until careful and 

somewhat extended consideration can be given 

to the invention of new ones. For the present 

report the existing terminology may perhaps 

be made to serve if temporary definitions are 

given and two terms introduced which, though 

new, are closely allied to two already in use. 

For layer 1 the word "soil" will be used in 

this report, the application of tl;le term being 

thus restricted to that surficial material which 

contains much plant and plant-modified matter.· The Latin word "humus" (soil) might be 

used in making a technical term, such as 

"humulite," especially as this layer generally 

contains much humus. 

Layers 2 and 3, which together have sometimes been called a colluvial deposit, deserve a 

substantive appellation, and for this purpose 

''colluvium," corresponding to ''alluvium," 

seems so natural that its apparent novelty is remarkable. The writer and perhaps others 

have used it orally for many years. This new 

term will be used in a broad sense as similar as 

possible to that given to the adjective form by 

Hilgard and others. It thus becomes a generic 

1 :Seeker, G. F., Reconnaissance of the gold fields of the southern 

Appalachians: U. S. Geol. Survey Sixteenth Ann. Rept., pt. 3, p. 289, 

1895. 

2 Merrill, G. P. op. cit., new ed., p. 287. 

a Deluc, J. A., Abrege geologique, p. 121, Paris, 1816. 

4 McGee, W J, The Pleistocene history of northeastern Iowa: U. S. 

Geol. Survey Eleventh Ann. Rept., pt. 1, p. 279, 1891. 

o Broadhead, G. C., Missouri Geol. Survey Rept., 1873-74, p. 64, 1874. 

6 Kinahan, G. H., Irish drift, subgroup meteoric drift: Royal Geol. 

Soc. Ireland Jour., new ser., vol. 4, pt. 3, pp.l15-121, 1877. 

or class name, and no doubt at a ·later date 

· the two species here referred to as layers 2 and 

3, and perhaps others, will be setoff and named. 

It seems necessary even now to recognize the 

two · species, and for these the Anglo-Saxon 

words "wash " 7 and "creep" will be used temporarily, though it is recognized that both 

words are in some respects objectionable. 

Layer 2 is perhaps the least well washed of all 

aqueous deposits, and "wash" has many other 

meanings. "Pluvialite" seems at present not 

quite satisfactory, even though the ancient 

Rorrians used "pluvialis" for "produced by 

rain." It would seem better to limit "pluvial" to the product of true rain, including 

accumulations of soil particles through the 

beating of rain, and to classify deposits made by 

little rills and other water running down hillsides as of streani origin. Not only in origin 

but in character such deposits are more similar 

to stream deposits than to material moved by 

rain beat. However, they should not. be 

classed with alluvium, and Hilgard's criticism 

of Shaler for so doing seems well taken. The 

Latin word "rivulus" (a rivulet) would thus 

seem to furnish a better foundation than 

"pluvius" (rain), "pluvialis" (produced by 

rain), or "nimbus" (pouring rain). "Creep" 

has been used by St!Veral authorities for the 

process by which layer 3 is formed, but no 

name seens to have been given to the result. 

"Creep" is not altogether satisfactory as a 

noun, but it may suffice until a better term is 

invented-perhaps "repite," from the Latin 

"repo," to creep. The Latin "gravitas" 

(weight) may be found useful as the basis for 

a generic term to include both •the products of 

slow creep and landslides which .gravitate down 

hill slopes. 

For layers 4 and 5 "upper residuum" and 

"lower residuum" may be used temporarily, 

though "residuum'' is misleading except as it 

indicates rough homology wi tl+ the un transported product of weathering in other regions, 

where, in the process of erosion, a mere soluble 

part of the rock is carried ·away and a less 

soluble part thus concentrated at the surface. 

A name for layer 6 can perhaps be dispensed 

with in this report. One seems to be needed 

that will mean unweathered, except for the 

7 See, for example, Hill, R. T., and Vaughan, T. W., Geology of the 

Edwards Plateau and the Rio Grande Plain adjacent to Austin and San 

Antonio, 'l'ex.: U. S. Geol. Survey Eighteenth Ann. Rept., pt. 2, p. 254, 

1898. 
142 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. 

weathering before arid during deposition, and 

signify that the deposits are comparatively uncemented, and ,another would be useful for the 

underlying Paleozoic rocks, which are both unweathered and cemented. It will be noticed 

that layers 1 to 5, inclusive, lie . in the belt of 

weathering, a part of the zone of katamorphism 1 

and those below in 'the belt cementation. Van 

Hise says: "The zone of katamhrphism is 

divisible into two belts-(1) an upper belt of 

weathering and (2) a lower belt of cementation. 

The belts are delimited by the level of ground 

water." · 

POSSIBILITY THAT SOME RECORD OF PLIOCENE 

' TIME MAY BE LEFT IN THE COLLUVIUM OR 

RESIDUUM. 

If throughout the broad area of uplands occupying·the central and northern parts of Mississippi east of the practically single row of 

counties in which the Mississippi bluffs and 

Pliocene terraces occur the ";Lafayette" consists in reality only of the outcropping portions 

of several underlying formations, the sedimentary record of Pliocene time would seem to be 

lacking in this area, for all parts of it have been 

.visited by geologists, and no Pliocene deposit 

other than the " .Lafayette" has ever been 

found. However, in a geologic sense the Pliocene epoch was not very long ago, and the 

questions arise: (1) May there not have. been 

made in this region in that epoch some deposit 

of which, though now mostlyworn away, some 

remnants are left on or just below the surface~ 

(2) Even if no Pliocene deposit was made, may 

not the colluvium or . the residuum contain 

material from other formations or display some 

other feature due to Pliocene events~ . 

COLLUVIUM; 

GENERAL NATURE. 

The material lying from 1 foot to 10 feet or 

so · below the surface of central and northern 

Mississippi is generally massive reddish or buff, 

more or less sandy clay, having at least ·the 

general appearance of such material as would be 

expected to develop through the weathering of 

underlying more or less sandy strata. · The upper part, which, especially in the western half 

:of the region, is less sandy, has be~il called" the 

.

1 Van Rise, C. R., A treatise on metamorphism: U. S. Geol. Survey 

Mon. 47, pp. 162-163, 1904. · 

yellow loam" 2 or "the brown loam." a- Some. 

if not all of the lower part has been regarded as 

''Lafayette" or Cblumbia. How~ver, several 

inconspicuous but nevertheless definite characteristics show that this lower part is neither 

residuum nor a sea or stream deposit . . It is not 

residuum, for it contains elements not found in 

the immediately underlying strata, and it commonly has a sharply defined base. It is not a 

stream or sea deposit, for it mantles the surface 

at . all. altitudes and slopes, it is comparatively 

unsorted, it contains fragments of soft ironcemented sandstone that show no wear, and it 

partakes from place to place of the nature of 

the underlying material . . Its features indicate 

that it has been produced by rain wash, modified perhaps from time to time by climatic 

changes, and hence it falls under the class name 

colluvium. Its general features are well shown 

in Plates LII and LIII and its possible origin 

suggested in Plate LIV. · 

The upper part, comprising much of what 

has been included in the brown or yellow loam, 

is believed to be partly eolian and related to the · 

loess and partly rriuch weathered colluvium 

and other surficial material. 

PEBBLES AND BOULDERS. · 

DISTRIBUTION AND LITHOLOGY. 

The study of the colluvium was begun at 

Oxford, where after a search of a few hours 

pebbles were found that seemed considerably 

larger than any occurring. in the underlying 

Wilcox. In a few days many such pebbles 

were found, some being so large as to be more 

appropriately called boulders, whereas in the 

Wilcox no pebbles over half an inch in diameter 

were found, and few more than a quarter of 

an inch. On a later field trip an estimate of 

the average number of exotic pebbles and 

boulders present on a unit area in northern 

Mississippi indicated between 20 and 100 to 

the acre. 

The suspicion then arose that the pebbles 

and boulders had come from some very high 

gravel deposit, practically unmodified remnants 

of which ·might be found in some part of 

Lafayette County or in the adjoining region. 

A careful search, however, was without result. 

Instead, more pebbles and boulder~ were 

2 Hilgard, E. W ., Geology and agriculture of Mississippi, p; 197,1860. 

a McGee, W J, The Lafayette formation: U. S. Geol. Survey Twelfth 

Ann. Rept., pt. 1, p. 393, 1891. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE Lll 

A. B. 

c. D. 

E. F. 

G. H. 

TYPICAL EXPOSURES OF COLLUVIUM. 

The colluvium shows little or no stratification and contains quartz pebbles and other elements commonly lacking in underlying 

formations, also angular fragments of iron-cemented sandstone. A, Colluvium about 2 feet thick, overlain by 2 feet of loess 

and underlain by Wilcox group, with an old soil at top, half a mile north of station at Oxford, Miss. B, Colluvium with fragments of iron-cemented sandstone at base, south edge of Oxford, Miss. G, Colluvium, from 5 to 15 feet thick, resting on Eutaw formation about 2 miles northwest of Leedy, Miss. D, Layer of iron-cemented sandstone fragments and concretions 

at base of colluvium 10 miles northwest of Holly Springs, Miss. E, Distribution of pebbles in subsoil 1! miles east of 

I u ka, Miss. Base of coil uvi um indicated by black I i ne. F, Distribution of pebbles in su bsoi I near top of Red Hi II, southeast 

of Jackson, Miss. G, Colluvium resting on Citronelle formation 1 mile south of Lamberts, Ala. H, Colluvium, largely 

red sand with layer of iron-cemented sandstone fragments at base, 4 miles northeast of Holly Springs, Miss. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE Llll 

A. . B. 

c. D. 

E. F. 

G. H. 

EXPOSURES SUGGESTIVE OF ORIGIN OF COLLUVIUM, SHOWING PARTICULARLY THAT IT COMMONLY FILLS 

HOLLOWS AND IS IN SOME PLACES THOUGH RARELY DOUBLE. 

Base of colluvium indicated in places by black line. A and B, Panorama of colluvium 10 miles southeast of Corinth, Miss. 

The concretionary mass beneath the collecting bag throws light on the origin of the surficial deposit, for it contains many 

Eutaw fossils, is very tragile,and has evidently been let down from the concretionary layer seen in the distance at a stratigraphic position abouf10 feet higher. The concretion is of a kind characteristic of this layer. The associated pebbles, 

however, are not COr:QI,nOn, if indeed such pebbles occur at all in the underlying Eutaw formation, and hence the con- clusion seems unav,q)dfible that the coarser parts of overlying strata have been concentrated downward in the development 

of the surficial forrn~tion and that none of the material has been transported very far. C, Small valley fi lied with coli uvi um 8 miles southeast ,.O:f"-C,orinth. D, Colluvium with very uneven base 1 mile west of luka. E, Colluvium with angular 

fragments of iron-cem~nted sandstone at base, Fourmile Creek, 2 miles east of Oxford. F, Colluvium with uneven base half a mile west\ of luka. G1 Gully filled with colluvium 71 miles southeast of Corinth. (Photograph by L. W. 

Stephenson.) H, Double(?) colluv1um half a mile west of luka. Upper 8 or 10 feet is from railway cut; below are two 

layers, each several feet th1ck, with q~artz pebbles at base. 
U. S. GEOLOGICAL:. SURVEY PROFESSIONAL PAPER 108 PLATE LIV 

A. 

c. 

B. 

E~ 

D. F. , 

RECENTLY FORMED DEPOSITS OF KNOWN ORIGIN AND HISTORY, SOMEWHAT RESEMBLING THE OLDER COLLUVIUM BUT STILL DIFFERING RATHER MARKEDLY. 

A, Exposure 7 miles northeast of Canton, showing coarse material left behind in a wash; perhaps the 

old colluvium was formed in part by the burial of a residual accumulation of this kind. B, Product of creep half a mile south of Oxford. C, Colluvium in bank of small stream 7t miles southeast of Byhalia. D, Colluvium in bank of small stream 7± miles southeast of Byhalia, somewhat 

similar to the old colluvium. E, Small filled gully St miles east of Grenada. F, Colluvium in 

bank of small stream 7-l miles southeast of Byhalia. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE LV 

B. 

A .' 

D. 

c. 

E. 

F. 

G. H. 

REMARKABLE POCKET-LIKE FE,ATURES, SUGGESTING FILLED BURROWS OR POTHOLES, AND PEBBLES 

AND BOULDERS OF QUARTZ AND QUARTZITE FROM COLLUVIUM. 

A, Filled burrows (?)extending below colluvium 3! miles southeast of Corinth, Miss. (Photograph by L. W. Stephenson.) 

B, Botryoidal quartzite from colluvium St miles south of Oxford, Miss. C, Filled burrows(?) extending below colluvium 4-! miles southeast cif Corinth, Miss. (Photograph by L. W. Stephenson.) _D, Pebbles and blocks of quartz 

and quartzite from colluvium 1 m i lenortheast of Buford M i lis, Miss. E, Fi lied burrow(?) extending below colluvium 

1! miles southeast of Washington, Ark. (Photograph by G .. D. Harri.s.) F, Botryoidal quartzite from colluvium 5! 

miles south of Oxford, Miss. G, Quartzite in place in colluvium three~fourths ofa mile north of Oxford, Miss.; the 

quartzite is so much weathered that it is about to fall to pieces. H, Near vieW of one of the filled burrows(?) just 

northwest of Strickland, Miss. (Photograph by L, W. Stephenson.) 
PLIOCENE HISTORY OF NORTHERN· AND CENTRAL MISSISSIPPI. 143 

found, every one lying at or near the surface 

with?ut regard · to altitude or physiographi~ r~latwns. The :pebbles and boulders not only 

differ f:om any In the underlying Wilcox, but 

they. differ · among themselves, falling naturally Into several groups. Lithologically they 

may be classified as iron-cemented sandstone 

or sandy iron oxide, quartz, quartzite, and 

chert. All the pebbles are of very resistant 

materials, and ~et _most of them are deeply 

weathered. · Thmr features are illustrated in 

Plate LV. 

The fragments of iron-cemented sandstone 

s~ow all degrees of rounding, rang~ng from 

pieces that are almost entirely angular to some 

t~at are nearly sp~erical, and it is generally 

~Ifficult to determine whether the rounding 

Is due to wear or. to concretionary or some other 

cementation. · 

The quartz pebbles are nearly white and are 

well ~oun~ed, but many show more or less deep 

solutiOn pits and some, particularly the larger 

ones, hav:e many cracks, probably made by 

changes In temperature extending over a 

long period of time. M:any of them have one 

or two flat faces, indicating that they have 

been broken by this process of insolation. 

~he quartz.ite pebbles and boulders display 

a wide_range In form. Some look so much like 

the quartz pebbles that a close examination is 

necessary to distinguish them. On the whole 

they are larger, more angular, and more of a 

cream or brownish color. The most striking 

features they display are the huge size of such 

blocks as those 5~ miles south of Oxford, one of 

which is over 8 feet ac:r:oss, and the botryoidal 

form of some of the same blocks and others 

elsewhere, as illustrated in Plate LV B D F ' ' ' . Another feature, which, though more obscure, 

is fully as significant with reference to the origin 

of · some of the quartzite, is the presence of 

gra~ns of certain minerals, particularly graphite, 

wh~ch are characteristic of the metamorphic 

regwn of northern Georgia and farther north. 

Except the boulders nothing has so far been 

found in the residuum that promises to throw 

light on the Pliocene history of _the region, 

t~ough here an.d there th~ clay and sand portwns seem to differ essentially from the underlying materials. · 

SOURCE. 

Th~ fact that all the pe,bbles and boulders 

are within a few feet of the surface and are· 

much larger than any found in underlying formations indicates that they came from some 

other formation, and they are sufficiently nu-

~erous and observations on the size of pebbles 

In the underlying strata are sufficiently abun- . 

dant to put this inference beyond question. 

The ~arge size and angularity of such quartzite 

blocks as those shown i~ Plate LV, B, makes the 

conclusion that they are less than a mile from 

their place of formation practically unavoidable, but. on_ the. other hand the p;resence 

of graphite In fmrly well rounded quartzite 

boulders 1 to 5 inches in diameter points 

clearly to a source in the area of metamorphic 

rocks 200 miles to the east. Obviously, then, 

the quartzite is of two v~rieties. Some was 

formed i!l the Coastal Plain by the cementation 

of sand grains with silica without the help of 

~igh temperature and pressur~. Such quartzItes have been found at numerous places in the 

Mississippi embayment, particularly in the 

Cla~bo~e group, the northernmost outcrop of 

· whiCh Is at Grenada. Being similar in certain 

peculiar features they may also be similar in 

conditions of development and perhaps also in 

age to the abundant· quartzite blocks scattered 

over some parts of the Dakota plains and the 

region to the west. On the other. hand, some of 

the quartzite must have been subjected to high 

pressure and fairly high temperature, else it 

would not contain delicate flakes of graphite. 

Such flakes could scarcely have been taken by 

water, wind, or any other agent from some other 

rock and incorporated in the sand of this rock 

at the time of its deposition without the delicate 

cleavage folia being broken up if not ground to 

powder or floated, b~cause of their lightness, 

far out among finer deposits. 

HISTORY. 

Past cycles.__:_Although something can be determined concerning the original source of the 

pebbles and boulde-rs, their history is largely 

problematic. The quartz and some of the 

quartzite pebbles and boulders evidently 

started in the region of metamorphic rocks 200 
144 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. 

miles and more to the east. At many places the eroded landward portions of formations 

the quartz and quartzite boulders are cer- now present in the region once contained pebtainly larger than any in the formations which bles larger than any now fou:nd in them. If 

underlie these places, and they seem larger the blockS of stone too large to be moved by 

than' those known to be in place anywhere -streams, rills, and rain wash were so numerous 

else in the region. The large quartzite blocks 

and probably the iron-cen1ented sandstone 

also were formed near by; for such sandstone 

occurs abundantly in many formations in 

the region particularly near the surface and 

some of the quartzite blocks are too large 

and too angular to have been transported_ 

far. The chert pebbles had .their source-in a 

region of Paleozoic limestone; probably most 

of them came from central Tennessee. In 

any event the pebbles and boulders are. evidently remnants of strata now worn away, for, 

they are not concretions or other forms originating in their present positions. The question then arises, Did those strata belong to a 

single formation that covered all or practically 

all the region, or did they belong to several 

formations, some or all of which are still represented by more or less continuous deposits~ 

It seems improbable, if not unbelievable, that 

they are the sole remnants of a single formation, for the removral of a formation from an 

area of 10,000 or 20,000 square miles would 

ordinarily proceed by its complete removal 

from some parts of the area before it had 

scarcely been dissected in other parts. The 

removal of '99.9 per cent or more from all 

parts of the area before all had been carried 

away from any part seems altogether beyond 

possibility, t~ough if possible for any formation it would be so for one consisting of sand 

and silt containing scattered boulders. If the 

boulders had been let down from a single formation th}3y should show some relation to altitude and surface features. · They should be 

most abundant near their source and in the 

bottoms of washes and gullies. 

The second hypothesis, that the boulders 

have come from several different formations, 

seems to accord with all known facts and principles. The original landward portion of any 

coastal-plain deposit, whether marine or subaerial, is likely to. be coarser than the seaward 

portion, and as the beds off-lap one another the 

landw~rd portion of each formation is exposed 

from the beginning of deposition, though the 

seaward portion is buried and protected from 

erosion. · Hence it is not at all unlikely that 

as to form a I thick bed, they would act as- a 

resistant stratum which in the 1course of erosion. 

would come to cap the highest hills. But . if 

they were scattered here and there in a matrix 

of sand and clay this :fint;~r material would he 

worn away from above, around, and below 

them, and they would be let down, with more 

or less lateral shifting, until by long exposure 

to the weather they would be broken to pieces 

small enough to be carried away. 

Little has been determined concerning the 

long gaps between the times when the pebb.les 

were integral parts of their parent rocks and 

the time or times when they reached their present positions, probably· before · the Pliocene 

epoch. The quartz pebbles may have passed 

through several cycles of weathering, transportation, and deposition. Probably they 

have traveled fat, and to this their rounding is 

no doubt partly due. On the other hand, their 

long travel is due partly to their ·rounded form . 

. Some of the quartzite may have had a similar 

varied history. The large, angular quartzite 

blocks, however, and the iron sandstones have 

never formed parts of any strata except those 

in which their cementation was accomplished 

and those in which they now lie. They seem to 

be similar in origin to the "graywethers" or 

"sarcen stones" of the English chalk downs, 

except that these are believed to be relics of 

formations not now . present in the region. 

Some of the chert pebbles, particularly the 

smaller ones, may have been taken from their 

parent limestones long ago, dropped in a 

Coastal Plain formation, and perhaps later 

taken up and redeposited once or many times, 

but it seems probable that most of them came 

directly from the Appalachian province comparatively late in geologic time, during one of 

the more recent epochs of uplift of that province. 

Present cycle.-The questions then arise, 

When and under what conditions were the pebbles moved from their places in the last formation of _which they formed a part to th~ir present positions, and how far did they travel~ 

These questions are more germane to the present discussion, for it is believed that their 

answers afford data on the Pliocene history. 
PLIOCENE HIST'ORY OF NORTHERN AND CENTRAL MISSISSIPPI. 145 

The data bearing on them are · also more abundant and less inscrutable. The distribution of 

the pebbles, their stratigraphic relations, and 

certain general inferences concerning rate of 

erosion seem to throw light on the Pliocene 

history of this region. 

The fact that the pebbles and boulders are 

nowhere concentrated into gravel beds or lenses 

but are widely and rather evenly scattered, 

particularly over the smoother middle and high 

portions of the surface, suggests that their lowering began, if indeed most of it did not occur, 

at a time when the region was lower and 

smoother than now, for if they had been let 

down by the erosion of their matrix while the 

country was rough they would have shown a 

tendency to move away from divides and down 

slopes, accumulating here and there in the bottoms of gullies. A similar argument indicates 

that their downward movement has not been 

great-at least not many hundred feet. 

Their apparently close genetic relationship 

and the fact that they rest upon Coastal Plain 

formations ranging from middle or early Cretaceous to Oligocene indicates that they came 

to their present positions not longer ago thari 

middle Tertiary time. , 

It seems much more likely that the pebbles 

came to approximately their present positions 

in Pliocene time than in any other epoch. If 

pebbles and boulders had been scattered over 

the surface of Mississippi in any epoch preceding the Pliocene, it seems very improbable that 

most of them would still remain near their 

original position, for in the opinion of the writer 

the assumption is well warranted that the up;. 

lands of central and northern Mississippi have 

been worn down more than 100 feet in Pliocene 

and Quaternary time. The present rate of 

erosion is probably about a foot in 10,000 years. · 

The pebbles and boulders have certainly been 

let down many feet, for they are found only in 

the colluvium. If they had been lowered much 

less than 100 feet, one might reasonably expect 

to find here and there remnants of the-beds from 

which they came, but no such remnants have 

been found. They have not been let down 

many hundred feet, however, for they are somewhat evenly distributed and are almost as common on divides as anywhere else. On sharpcrested and steep-sided ridges and knobs they 

are scarce or lacking, but on rounded divides 

they seem as common as anywhere else. No 

beds known tobe of Quaternary age have been 

so extensively eroded. Hence it is inferred that 

the beds from which the pebbles and boulders 

came were worn away, in part at least, in Pliocene time, and the somewhat even distribution 

of the pebbles and boulders suggests that the 

region lay lower in that epoch than it does now. 

Just how the colluvium was formed is not yet 

clear. The distinctly greater abtindance of 

coarse material at the base and the great 

extent of the deposit can apparently be explained best by climatic change, for ordinarily 

in the wash of soil down a slope there is little 

chance for such sorting. It would therefore 

appear that the basal coarse material was accumulated under different conditions from those 

which .existed while the upper, finer part was 

being formed. 

The general history of little hillside gullies in 

the region to-day seems to consist of (1) cutting 

of the gully, (2) deposition of gravelly and sandy 

silt in its bottom, (3) gradual obliteration of the 

gully by wash of fine material from above and 

the sides. This proce~s being qbserved, the 

resulting deposit was carefully . compared with 

the older colluvium, but it was found to differ 

markedly on the whole, though perhaps not in 

any single essential respect. The principal difference is that the basal coarse layer is much 

more irregularly developed in the present-day 

colluvium. This may be accounted for by the 

fact that owing to the activities of man in clearing forests and pasturing, etc., washing proceeds more rapidly than formerly, with results 

that differ not only in extent but in kind; but 

this seems scarcely an· adequate explanation, 

and hence the writer is inclined to accept the 

hypothesis of climatic change. 

On the other hand, objections may be raised 

'to this hypothesis. The greatest climatic 

changes since middle Tertiary time have been 

those of the glacial epoch, and it might be reasonably assumed that the colluvium was pro..:. 

duced by them, but if so it should be possible to 

find several deposits of colluvium of different 

ages and in many places one deposit superimposed upon or cutting another, whereasin only 

a few places, as in the railroad cut half a mile 

west of the depot at Iuka (see Pl. LIII, H), has 

one colluvial deposit been found above another. 

In any case many of the pebbles and boulders 
. 146 · · SHORTER CONTR.IBUT'IONS TO GENERAL GEOLOGY, 1917 • 

seem to date back to Pliocene time, though they 

may not have reached their present positions in 

that epoch. 

Except the pebbles and their arrangement 

little that promises to throw light on the 

Plioce:p_e history of the region has so far been 

found in the colluvium, though here and there 

the clay and sand portions seem to differ from 

underlying materials. ·One of its very remarkable features consists of forms that resemble 

filled burrows or potholes and extend down 

into underlying material. Harris 1 reproduces 

a photograph (see Pl. LV, E) showing one of 

these burrows;which he ascribes to a Cretaceous 

reptile, a Cretaceous age being assumed because 

the supposed burrow is in Cretaceous strata on 

a hillside and higher strata crop out near by. 

But the writer has found a great many of them, 

and all are connected with the colluvium. The 

best· examples of them have been found by 

L. W. Stephenson in new cuts along the Illinois 

Central Railroad 5 to 10 miles southeast of 

Corinth, Miss., and pictures of some of these 

are shown in Plate LV. To judge by the 

present rate o{ erosi~n these burrows would 

seem to be of late Pliocene or early Pleistocene 

age. 

RESIDUUM. 

GENERAL NATURE. 

Below the material which has been moved 

down slopes a greater or less distance by some 

agency, or at the surface in places where such 

material is lacking, ·lie strata of different ages 

that are in almost the exact position in which 

they were deposited and yet have been subjected to the somewhat effective weathering 

process of frequent wetting and drying. (See 

Pl. LVI.) They consist for the most part of 

irregularly bedded sand or clay or mixtures of 

the two. ' The upper few feet of this member, · 

here called the upper residuum, commonly has a 

different appearance from the underlying part. 

In some places it is huffish gray or dull colored, 

contrasting with the brigh~er-hued strata below, but more generally it has red, brown, or 

black colors due to iron oxide, which here and 

there constitutes more than half of the deposit. 

(See Pl. LVII.) Below is a greater thickness of 

bright-colored and more sharply defined strata, 

the lower residuum, extending down to the 

dry-season water table. 

1 Harris, G. D., Oiland gas in Louisiana: U, S. Geol. Survey-Bull. 

429, pl. 15, B, 1910 . 

IROi,q" CONTENT. 

It seems to have been generally assumed 

that the iron which is so abundant or at least 

so conspicuous near the surface in Mississippi 

was deposited in one form or another along 

with · the sediments .with which it is now mingled, except for so.me shifting by solution and 

redeposition. For example, Crider 2.says: "The 

water passing through the Lafayette takes up 

iron oxide in solution-and, being checked by the 

underlying impervious bed, ·deposits the iron 

oxide, thus cementing t~e sands into a compact mass." It is also assumed that the relative abundance of red color near the surface 

is due to some chemical change induced by 

exposure to the weather. Thus Berry, in- the 

quotation given on page 130, ascribes the redness 

of the surficial material to dehydration of ferric 

oxide.. Hilgard,3 on the other hand, says that 

the color is due to ,"hydrated peroxide of iron 

or orange-yellow ocher." So far as the writer 

can determine many of the more or less reddish 

tints displayed may be due to either hydrous 

or nonhydrous iron oxide, and not only limonite 

and hematite may be present but perhaps 

turgite or other oxides and also iron compounds 

that are not red, such as the carbonate, sulphate, and sulphide. 

If the iron has been subject to solution and 

redeposition and to change in constitution, it 

is reasonable to suspect that these processes 

would have been affected by_ any change in 

climate or altitude, by any burial · benea.th 

strea~ or sea. sediments, and perhaps by faunal 

or floral changes. If so, the question presents 

itself, May not some Pliocene events have been 

thus recorded and the record preserved ? 

Although the iron 'compounds ·seem to have 

been modified more than other portions of the 

residuum, perhaps other materials -may also 

contain scraps of Pliocene history. A search 

has not yet brought to light any considerab~e 

record of this sort. Evidently one reason IS 

that such records are more obscure than might 

be expected, and a:qother is that the greater 

part of any rec?rd that was. m.ade has been 

effaced ·by erosiOn. The pr1nc1pal effect of 

such chanO'es as those mentioned would have 

been felt ~thin 50 feet of the surface, and the 

writer believes that most of the region h~s 

2 .Crider, A. F., Geology and mineral resources of Mississippi: U. S. 

Geol. Survey Bull. 283, p. 46, 1906. 

a Hilgard, E. W., op. cit., p. 7. 
U. s •. QEOJ..OGIC~L S.URV.EY PROFESSIONAL PAPER 108 P)..AT,E LVI . 

A. 

c. 

B. 

D. 

E. F. 

RESIDUUM OR MATERIAL IN PLACE BUT MODIFIED SOMEWHAT BY WEATHERING, THOUGH 

· LITTLE IF ANY PART HAS BEEN REMOVED. 

Dr. E. A. Smith believes that much of the iron cementation shown in railway cuts has occurred since the 

cuts were made, but some is apparently much older, perhaps PI iocene. The residuum seems to contain 

material brought to it in solution and in the form of minute particles by the way of pores, from strata 

removed in the PI iocene and other epochs. A, Tuscaloosa formation 5 miles east of Tuscaloosa, Ala. 

B, Wilcox group 2 miles east of Holly Springs, Miss. C, Wilcox group at Oxford, Miss. D, Eutaw 

formation about 11 miles northwest of Leedy, Miss. E, Wilcox group 6! miles east of Sardis, Miss. 

F, Wilcox group 13 miles east of Holly Springs, Miss. 
U. $. GEOLOGiCAL SURVEY PROFESSIONAL PAPER 108 PLATE LVII 

B. 

c. D. 

E. F. 

G. H. 

VIEWS ILLUSTRATING REDDENING AND :PROBABLE CONCEN I RATION OF IRON COMPOUNDS NEAR THE 

SURFACE. 

A, One mile north of station at Oxford, Miss. B, Gravel composed of hollow pebbles of iron oxide 1 mile north of wharf at 

Natchez, Miss. (See Pl. L.) C, Red sand with much iron oxide over· impervious white clay, Grand Junction, Tenn. 

D, West side of Fourmile Creek, 2 miles east of Oxford, Miss. E, One mile south-southeast of Oxford, Miss.; upper part 

of white material is impervious clay and basal part of overlying red sand is more than half iron oxide. F, Three-fourths 

of a mile north of Oxford, Miss. G, Three-fourths of a m.ile south of Oxford, Miss. H, 4! miles south of Oxford, Miss.; 

sand is white under clay lens showing in upper part of view but reddened to each side. 
PLIOCENE HISTORY {)F NORTHERN AND CENTRAL MISSISSIPPI. 14 7 

been reduced more than that · amount since II water table, and many iron crusts ma).Je inPliocene time, and an additional, probably terpreted as marking a present or former posistill greater, amount during Pleistocene time. tion of the ground-water surface, but these 

However, other facts point to the .inference crusts are comparatively thin instead of 

that the fundamental assumptions above men- characterizing the saturated zone or its upper 

tioned need some modification. part as a whole, evidently more of the iron-

· It seems probable that the iron was not de- j rich sand is related to impervious beds than to 

posited along with the sediments where it is present or former positions of the water table, 

. now found, but that it has been moved and and the arrangement can be much better exconcentrated not only through solution and / plained by a mechanical process of downward 

redeposition but also mechanically. The basis concentration, the minute particles of iron 

of these inferences may be briefly state'd. being swept downward by rain water as it 

Much of the iron oxide is in the form of minute sinks into the ground a.nd accumulating 

discrete grains, which are corrimonly less than at the top of the ground water, where the 

a thousandth of a millimeter in diameter, and rain water. js stopped or its velocity greatly 

some are less than a ten-thousandth. Many checked. · 

of them are thus smaller than the pores of sand It should be remarked, however, that a large 

and other surficial material an4 must be car- part of the iron oxide is very irregularly disried about by percolating water. The main tributed, in an unaccountable manner, and 

movement is naturally downward, for the much of it has -evidently been affected by 

downward movement of water after a rain is[ solution and reprecipitation, for some of it fills 

more rapid and more effective in washing than pores completely as a practically impervious 

the upward and lateral movements due to[ mass and some of it coats sand grains, adhering 

capillarity and hydraulic gradient. As a rei to then1 closely. The iron oxide is thus found 

suit and also because the comparatively im- in two principal f<;>rms-as a compact mass 

pervious bed acts as a strainer the iron i~ clinging to sand grains and filling pores and as 

concentrated· at the base of a porous layer andl loose particles scattered through the pores. 

the top of an impervious layer. fany specirr1ens of. what seen1s to be deeply 

The accumulatio~ of iron oxide at the top o~ iron-stained red sand are easily cleaned by 

a clay layer, as illustrated by the quotation washing in water, and under the microscope 

from Crider on page 146, has been ascribed to the iron oxide is seen to consist of separate 

transfer in solution, but the assigned reason! particles. The iron · thus seems to be transfor precipitatio~ of the iron seems inadequatel ferred both mechanically and in solution, and 

Only two poss1ble causes suggest themselves, there is reason for believing that the dominant 

and both seem probably ineffective. First, th ~ process is a downward mechanical concentraimpervious bed is generally different in chen1J tion, followed by a slight rearrangement and 

ical constitution froll_l the ·pervious bed, and compacting by solution and redeposition. 

something in it may cause a precipitation of ·In son1e places, particularly where erosion is 

the iron, but there is little reason for assuming proceeding rapidly, the n1aterial most enriched 

that such a reaction occurs, particularly as thJ with iron lies at the surface, the iron having 

iron is concentrated only at the top of the imT come from material eroded away. In a railpervious bed. Second, it is conceivable that way cut half a mile south of the station at 

the iron oxide is slowly being precipitated frorrl Oxford about 5 feet of colluvium overlying 10 

ground water all the time, and the reason wh~ feet of sandy Wilcox strata is exposed. A 

more of it accumulates at the top of clay beds series of samples were taken at this place and 

than elsewhere is -that water is more nearl~ submitted to Chase Palmer, of the United 

perpetual at such positions than elsewhere. States Geological Survey, with the request that 

But if this is so, it would seem that iron should the percentage of total iron· in each be deteraccumulate at and below the water table and mined. The results show a concentration of 

that the sand above should be robbed of its iron at the present surface and a similar coniron content. In many places there seems to centration at the old surface which existed 

be a concentration of iron at the top of the before the colluvium was laid down. 
148 SHORTER CONTRIBUTTONS TO GENERAL GEOLOGY, 1917. 

Percent' of metallic iron in colluvium and residuum hal/ gravel may have been swept from the region a mile southwest of station, Oxford, Miss. under study. 

[Chase Palmer, analyst.] As detailed topographic maps have not been 

Colluvium: Per cent. made for most of Mississippi, full and ex1 foot below surface.······ ·· ····· ·· ····· 3· 85 act data regarding the surface features, such as 

2 feet below surface ......... . .......... ·. . . . . 3. 08 

3 feet below surface._. __ _ , _______ .__________ 2. 58 are necessary for their interpretation, are com4 feet below surface . ............... . ........ 2. 06 partitively meager. The literature concerning 

Residuurp. : Mississippi seems to · contain no .descriptions of 

6 feet below surface.·---·----- -- ---- --·-·- · 3. 18 peneplains and little reference to terraces. The 

8 feet below surface · · · · · · · · · · ·-· · · · · · · · · · · · · 2· 85 drainage lines are well shown ori many maps of 

~~ :~ ~:~~; ::!:~:~ ~ ~ : ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~: :~ the State, but they appear in greatest detail on 

14 feet below surface ... . ......... . ........ . . 89 the General Land Office map, upon which most 

.BEARING ON PLIOCENE HISTORY OF REGION. 

If the process of downward concentration of 

-iron is now operative it has presumably been 

in progress for ages, though perhaps modified 

from tin1e to time by climatic changes. If the 

surface of central and northern Mississippi has 

been lowered by erosion 100, 200, or 300 feet 

since the beginning of the Pliocene epoch, and 

the process of concentration has been active 

during this tin1e, some iron from strata worn 

away in Pliocene time is probably present in 

the region to-day. But the search for some 

record of climatic an~ other changes in the 

iron deposits has thus far been fruitless. Ironrich layers and lenses lie at many positions; 

which so far seen1 quite discordant, and much 

of the iron-cemented sand does not follow the 

bedding but cuts across it at various angles. 

PHYSIOGRAPHIC RECORD. 

NATURE OF DATA. 

In order to decipher the physiographic history of a region it is necessary first of all 'to have 

knowledge concerning areas that are approximately flat or that lie at accordant altitudes, 

for such features, whether large or small, may 

mark periods of erosion, producing extensive or 

incipient peneplains; of erosion and sedimentation, particularly in connection with stream 

terraces; or of sedimentation essentially- alone, 

such as produces the surfaces of many 8ea,Jake, 

and even stream deposits. Second, the investigator must know the arrangement of drainage 

lines. Third, he must know to some extent 

how readily the rocks underlying different 

parts of the region yield to erosion. Fourth, he 

can often use certain other facts concerning the 

nature of the sedimentary strata of the region 

and adjoining areas to which silt, -sand> and 

commercial maps are based. Information of 

other sorts is still comparatively scarce, though 

it has been considerably augmented by the 

present study. · 

The basis of the inferences set forth in this re-

. port consists of published maps and descriptions 

of the region; unpublished topographic and physiographic observations of other geologists, particularly Dr. E. N. Lowe, State geologist, and 

members of the section of Coastal Plain investigations of the United States· GeologicaJ Survey; 

results of spirit leveling, the profiles, generously furnished by many railroads (see. Pl. 

LVIII), being of especial value; and notes on the 

appearance of the surface, made by the writer 

as he traveled by rail and buggy throughout the 

region, these notes being correlated with points 

of known altitude by the help of barometricreadings between such points. 

As good topographic maps are not available,. -

it was necessary to use a barometer constantly, 

and although the readings of this instrument 

are subject to unknown and variable corrections, still, by using all possible means of 

checking, results of some value were obtained. 

The checks consisted of established bench 

marks, Weather Bureau records of air pressure. 

for the times during which the bar_ometer was 

used, the general average diurnal variation in. 

air pressure, previous barometer readings, and 

occasional sights with a hand or spirit level.. 

The appearance of the surface to .the unaided 

eye, although scarcely usable in checking even 

a barm;neter, was nevertheless recorded, especially where appearances and barometer readings were discordant. Part of the time a barograph was used to record the air pressure for 

the day at a ~ingle point, generally in a hotel, 

and .the barometer readings were modifie~ t() 

accord with those of the barograph. 
U S GEOLOGICAL SURVEY 

W 0 L F Lamar R I V E R VALLEY HEADWATERS COL DWATER R I V E R 

Grand Junction 

. · c· £N RTtN SVIL L£ M ISS. ; •••hd\lgan ity L£ FROM GRAN{) Ju'VCiJON, T IV .. TO MA 

: pRof1 · 

.• . / _ •• •••• ••• ·-. .•• ,_ .... ,, . , •• , •• , ___ ,. , ___ ,. , -. ····~· .. _r,/',_ ....... , • .,_... Col'J;;:!:r .. · .... ... . 

;·- - · ... . .. ... ............ -.. .. ----------· Hen18ndo -.' '- ---•"\· -~'" ' .. --· r ..... -----..... _, ......... ____ .......... .. 1 ...... ___ .. _ ... _ .. _ ..-.. _ --:------.... _ .... / .. _ ............. _ ... ......... .. ........... , --

500-

20 

400-

20 

10 

40Q300 

200 

tOO 

210 miles from Jackwn. Miss. 205 

Abbev ille 

' 

165 

S<;obey 

_/ .~" .. '"---.-.... -- Tillatobe 

' -... 

Coffeeville 

125 

62·mi!e 5iding 

BOTTOM LANDS, HAYS CRE~~ 

Col l~ge Hil l 

, ........ _,. ...... ,-:·-......... --....... _ ..... , ...... .... '\; .. .. sardis 

160 

H~rdy 

---...... _ ... __ ---·-----...----

Torrance 

120 

Horn L4ke Nesbitt 

200 ISS 

Oxford 

r a.l.lahatchi.e 

·.,_·.'•.·.·,!·--V>,•, __ .-,-,, _____ ,___ Rtver 

---- -~--- .... .. ! ..... : .... ·--;•'" " - -----........... " .................. .. , ..... _______ __ _ ---j "---......... - - -

T"l l,hatchie ' Bates'ville 

155 

115 

YaLobusiUL Rb•er 

Grenada VALLEY 

110 

190 185 

'-'--.... --~--¥ ___ .......... _ ---; ..... ----- Courtland Pdpe 

150 145 

5 I D E, BATUPAN lli~tt R I V E R 

105 

BLACK R IVE R 

Love 

~" __ ,._, ''-,.__ ... ~ ... ~ ... ~>~ _ ... "' 

---....... ---

Duck Hill 

100 

Du t 

' 

140 

ater 

180 

95 

Aberdeen Junction BO T T OM 

135 

L A ND S , 

PROF"ESSIONAL PAPER 108 PLATE LVIII 

Spring Creek 

TolJ.ahatchi-. -t. 00 

!Uver 

~----- --~------------- -~~-~---~-~~~~~~~~_,--,3 00 ~-- .. -\ ..... ---------- Senatobia 200 

100 

0 

175 170 

~on 

::::::::: ...-- ---: ... S ..c:-: ..=- ~~...:..:.~:.::..::::::::.::......_.~~..,c,-.,.&:.--::;·-~~-3oo 

200 

100 

0 

90 

Goodman 

B I G B L A C K R I V E: R 

13 0 

-400 -~-----~-------1 300 

200 

100 

0 

0~----------------~---------.--------~--~----~--~----~--~----~--~---.----~--~----~--~----r---~------------~----.---~----~--~----~---.----~--~----~--~----s~--~----~------------~----L o 45 

200 

100 

0 

85 55 80 75 70 65 60 

v,u~h"" BLACK , RIVER 

200r-·---------~~---------------/--------~--_/ 

Pickens I 

' B OT TOM LANDS, BIG BigBlackRiver Canton 

: C ANTON TERRACE 

300 

200 

tO 100 

0 

40 35 30 25 20 15 10 

Mil l Hazlehur11t t~ rt.in ill e 

400- Asylum switch Jack:!!on Terry B R 0 0 K H A v N L A -400 

300 

200 

100 

0 

NORTH --- 0 ~ SOUTH 5 10 15 20 25 3 0 

PROFILES ALONG ILLINOIS CENTRAL RAILROAD FROM GRAND JUNCTION, TENN., THROUGH JACKSON TO MARTINSVILLE, MISS., AND FROM A POINT NEAR MEMPHIS, TENN., TO GRENADA, MISS. Profiles show surfa,ce features before cuta and fills were made. 

Figures along bottoms of profiles show distances north and south from Jllcltson, Miss. 

Vertical I!Cale exaggerated about 20 times. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE. LIX 

A. B. 

c. D. 

E. F. 

G. H. 

VIEWS ILLUSTRATING OCCURRENCE AND 'MODE OF · DEVELOPMENT AND THE EXCELLENT EXPOSURES 

AFFORDED BY OLD FIELD GULLIES. 

Such gullies may have played an important part in the Pliocene erosion of the region, though they were no doubt much less numerous than to-day. The part played by the sod in resisting erosion is well shown. Many of the .gull ies have rounded 

instead of V -shaped heads and evidently grow neither through erosion by water flowing into their heads nor through softening of materials by underground water issuing as a seepage, but only because of the fact that the rain which falls into 

them finds erosion easier than that which falls on sodded areas. A, Recent colluvium on border of flood plain 1t miles 

south of Delay. B, 8 miles south-southeast of Yazoo City. C, 5 miles west of Grenada. D, 12 miles east of Batesville. 

E, 7 miles west of Oxford. F, 12 miles west of Oxford. G, 15 miles east of Batesville. H, At Oxford; shows filling after 

deep erosion. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE LX 

A. B. 

c. D. 

VIEWS ILLUSTRATING PENEPLAINS AND MONADNOCKS. 

A and B, Peneplain with monadnock ii1 distance 6 miles east of Holly Springs; the road on the right follows an even-crested divide, whose top was once a part of 

the peneplain. C, Thackers Mountain, a monadnock, from a point 5~ miles south of Oxford. D, Flat plain at altitude of 600 feet (barometric) on Ripley road, 

11 miles east of Holly Springs. 
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPPI. 

GENERAL SURFACE CONFIGURATION OF THE known as Thackers Mountain stands on the 

REGION. west side of the Illinois Central Railroad 5 

The surface features of northern and central miles southwest of Oxford, and another, someMississippi are those of comparatively rough what lower, known as Summerville Mountain, 

elevated coastal plain, sculptured for the most is 9 miles west-northwest of Oxford. These 

part in only slightly consolidated sand and hills are not capped with gravel or other mateclay, the layers of which are nearly fiat but rial differing from the country rock, though as 

lenticular and commonly ill defined. The alti- a rule each one has a layer of sand firmly cetude ranges from about 800 feet above sea level men ted by iron at or near its top. · 

at the tops of some of the higher hills in the The question then arises whether any or all 

northeastern part of the State to about 100 feet of these striking isolated hills have been 

on Mississippi River at Vicksburg, in the south- formed in one and the same cycle of erosion. 

west corner of the area here discussed. The Apparently the two in Lafayette Qounty ~ere 

profile in Plate LVIII shows some of these not formed in the same cycle, for one, Thackers 

features. · Mountain, rises above a· high divide, whereas 

The areas underlain by sand are mostly 

rough, and some of them are almost rugged. 

The ·areas of clay and limestone are less extensive and smoother; some parts, as for example 

the uplands north .of West Point, being strikingly fiat and prairie-like. A part of the fiat 

country around West Point, however, is made 

up of terrace tops. The principal areas of 

clay and limestone are along the ea&t and south 

sides of the region. The divides in these areas 

are lower than in the sand areas; on the other 

hand, the valley. bottoms seem somewhat 

higher. . Old field gullies are common in most 

parts of the State, and their general form is 

illustrated in Plate LIX. 

The physiographic record of Pliocene time in 

Mississippi seems to fall into three principal 

divisions. One is found in the upland surface 

forms, another in high terraces along Mississippi. River, and a third in the arrangement of 

~ drainage lines. 

UPLANDS. 

. MONADNOCKS. 

the other, Summerville Mountain, is on the 

side of the · broad valley of To by Tuby Creek, 

and its crest is scarcely so high as the divide 

between this stream and Clear Creek, the next 

stream to the southwest. According to barometer readings, it is also considerably lower than . 

the divide between Tallahatchie River and 

Yocona River, the major drainage lines to the 

northwest and sou.theast. 

Most of the isolated hills, however, stand on 

high uplands and their tops show more or less 

concordance in height . . Those in the northeast _ 

corner of the State reach about 800 feet above 

the sea; those in the Pontotoc Ridge country, 

east of New Albany, about 700 feet; and 

Thackers Mountain about 600 feet. In Choctaw County hills that are perhaps similar in 

history have crests at about 650 feet, suggesting that if they are of the same age . the area 

including Choctaw County has been uplifted, . 

for it is no more favorably situated with reference to drainage lines than the area to the 

north. The similarity in height of these isolated hills is not very close, however, the high 

hills in any county commonly showing a disSeveral more or less distinct stages in erosion / cordance of 100 feet or more. · 

are reco~d.ed in the surfac~ features. T~e I The fact that no such large m~sses of ~ard 

most stnking and most legible part of th1s rock seem to be present anywhere 1n theregwn, 

record consists of isolated monadnock-like hills except on the tops of scattered hills, suggests 

which rise above the general upland where the that their formation was started by conditions 

underlying material is sand, for sand seems to different from those of•to-day. If other such 

be much more favorable to their preservation masses were present in the earth and were 

than limestone or clay. Several of these hills sharply defined and not close together, no 

are to be seen in the vicinity of Iuka; one is 3 doubt in the progress of a single cycle of erosion 

miles southwest of the town and another· 5 they would come to cap isolated hills, but unmiles northwest . . Blue Mountain, south of less the strata were horizontal and the hard 

Ripley, and parts of the Pontotoc Ridge also masses occurred in only one layer the hills 

belong in this class. A striking isolated hill would be discordant in height. As a matter of 
150 SHORTER CONTRIBUTIONS TO GE"NERAL GEOLOGY, 191'7. 

fact, strata belonging at the horizons of the 

iron-cemented hill caps: are well exposed at 

many places and are within reach of wells in 

extensive areas, but no, such large; hard, and 

sharply defined masses have been found except 

on hilltops. Hence it must apparently be infeiTed that the formation of the hard masses 

began on a peneplain now marked by the tops 

ofmost of these hills and that instead of .disintegrating with exposure to the weather the 

masses that now cap the hills have become 

more and more consolidated.· The processes 

~ 

~ 

In any case their rough accord:ance of•summits 

suggests a peneplain. · 10n the ·other hand, the 

hard caps ar:e .not being softened by weather 

and even seem to be due in part to the forms of 

the hills, as well as the forms of the hills to the 

hard caps. 

EVENNESS ·AND CONCORDANCE IN HEiGHT OF 

LOWER CRESTS. 

Throughout~;tlarge partoftheregion the divide , 

crests are so ~early .even that more and better 

wagon roads .are to be found on them than 

. a~ any other topographic position. 

This is well shown in Plate LX, 

which shows also in the distance 

two low mon:adnocks. ~ The even- · 

ness, _howev.er, though co.mmonly a 

striking feature, is throughout 

, most of. the region onJ.y relative. 

Generally the divides in any area 

are not only even crested but somewhat similar in height, the differences in altitude being as a rule only 

50 -to 100. feet. At many places, 

how.ever, the average altitude of 

the divid seeems to increase rather 

~b:ruptly by 50 or 100 feet, and the 

increase can scarcely be explained 

Contours showing atzitude and 

shape of' restored .Cretaceous ~Jeneplain" after Hayes and 

Campbell, 1894 

Contours showing attitude and 

shape of Paleozoic floor u.nder 

Cretaceous deposits 

· by the presence of harder rock. In 

some places the rise is so abrupt 

as to be unquestionable, but more 

. commonly there is room for doubt 

as to the existence of any signi:fi:... 

. cant boundary of a -physiographic 

feature. _ 

The scarcity of exact ·data as to 

altitude, the uncertainties of the 

barometer' and the common lack 

of definition of the surface features 

make the unraveling of the upland 

FIGURE 22.-Diagram shoWing the slope of the Cretaceous peneplain,' according to 

Hayes and Campbell, and the slope of the Paleozoic floor beneath the Cretaceous deposits of Mississippi, which has been considered as being equivalent to this peneplain. 

. erosional record very difficult. At 

hundreds of places it is evident 

that more of the upland surface lies 

at one, two; three, or even four alti-

. The contours shoWing the Cretaceous surface are. copied directly from an illustration in 

the pioneer description of peneplains of the southern Appalachians, which may be regarded as a first approximation and a representation of a hypothesis of the -authors. 

Some believe that no peneplain of the Appalachians would, if restored, have the form 

of that here represented, but there is general agreement (1) that peneplains· are represented in the Appalachian province, (2) that they slope outward from a central region at an angle no greater than that represented here, and (3) that in a belt around 

the margin of the pro; ince the slope decreases outward. 

. .tudes than at any intervening positions, · and that the difference is not due 

altogether to differences in hardness of rock 

nor to a combination of such differences and 

some other cause. But satisactory proof 

that any particular feature records a change . 

-in the rate or nature of erosion is difficult 

to obtain, and the correlation of features that 

·probably record stages of erosion is f~lly as 

of underground mechanical concentration of 

· ·iron oxide outlined on page 147 seem in accord 

with this inference. It seems possible if :not 

probable that the hard masses began to develop 

in little hollows on a smoothish surfac.e and then 

after uplift and during dissection the hard 

masses caused hills to develop where there had 

been hollows . . Had there been no peneplain 

there ~ght have been no such isolated hills. . difficult. 
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPPI. 151 

However, after several months of study the 

writer has become convinced that several 

stages of erosion are recorded in the uplands 

and that these stages can be proved when detailed topographic maps are made. The data 

collected suggest that surfaces of concordant 

height stand at four different main positions. 

One position is represented by the tops of 

most of the monadnock-like hills. A second 

is represented by the comparatively evencrested high divides of the Pontotoc Ridge 

and some other less conspicuous features, 

particularly in a belt extending north-northeastward from the headwaters of Pearl River 

to Tishomingo County. A third, which is at 

present by far the most extensively represented, 

is. that of most of the divides of the region. 

A four.th is represented by the tops of innumerable shoulders or benches, 

which are broadest near Missis- NW. 

According to Hayes, 1 the region lying northeast. of the northeast corner of :Mississippi, 

including n1uch of central Tennessee and 

northeastern Alabama, belongs in the Highland Rim portion of the Interior Lowlands 

division of the southern Appalachian province. 

(See figs. 22 and 23·.) Later studies have not 

led to any essential revision of this classification. Hayes and Campbell 2 describe two peneplains in · this region. . The older and higher 

or "Cretaceous peneplain" slopes westward 

and southwestward from 2,000 feet above 

sea level in Warren County, Tenn., 60 miles· 

southeast of Nashville, to 1,000 feet above sea 

level within 100 n1iles, or at the rate of about 

10 feet to the n1ile. The second or Tertiarv 

peneplain is represented on Plate' YI .of -th~ 

report cited, reproduced in. part in figure 22, 

SE. 

sippi River and on the more yield- z,ooo ___ c;:_u_'"'2~~~~nd ttretaceous"J . Hi hi and Rim---------'--- e_e_n~E~~~ ---_-:. ::_ ':!.!1?'2_1~~d_R!._m_trJ~~sY~L e_e~e_p!_?i_9.. 

ing formationS. 1•

000 Prese.nt uplands.'of . . 

Sh uld d b h northeastern MISSISSippi 

0 ers On SpUrs an enC eS Floor under 

on hillsides which are accordant l _____________ c_re_ta_ce_o_us_de_p_os_it_s ____ ____::~__., . ~1,000 

in altitude but not sufficiently so 0 10 20 3<J 40 50 60 70 SO MILES 

to be terrace re1nnants and which 

bear no terrace deposits are common at still lower positions, but 

they are even more difficult of 

correlation and interpretation. 

Any single one might be due to 

a resistant bed or to some unknown cause. However, after 

traversing n1any valleys the 

FIGURE 23.-:':iagrammatic profile to show relations of upland surface features of Mississippi to the peneplains in a portion of Tennessee to the northeast, described in the text. 

This profile indicates that the peneplains ofthe Appalachian province are much younger 

than the floor beneath the Cretaceous sediments, and apparently the older of the two 

plains represented is younger than the floor under the Tertiary. This representation of 

the Appalachian peneplains seems subject to amendment of two principal sorts. ·First, 

the restored Cumberland peneplain may be warped up over the Nashville uplift, which 

falls in the left center of the figure; and, if so, the apparent discordance between it 

and the floor under the Cretaceous would be reduced. Second, there is strong indication that more than two peneplains are represented in this region, and each has a ge\].-

eral slope less than those represented, and, if so, the discordance would be increased. 

writer has become convinced that below the 

four upland flats referred to above, two or 

more changes in rate and nature of erosion are 

recorded in features that are not stream or seacut terraces. 

RELATION OF PHYSIOGRAPHIC F:mATURES TO 

THOSE OF THE APPALACHIAN PROVINCE. 

GENERAL CHARACTER OF SURFACE ALONG BORDER. 

In the northeast corner of :Mississippi and 

adjoining parts of Tennessee and Alabama 

opportunity is afforded for tracing the peneplains of the Coastal Plain northeastward into 

the Appalachian . province, where three peneplains have been mapped and described and 

have become widely known. Fortunately 

several quadrangles in this critical border area 

have been mapped topographically. 

as having a westward and southwestward slope 

in the same region from 800 to 600 feet in 

60 n1iles, or 3 1 feet to the mile. Hayes 3 a 

little later deseribed three peneplains- under 

the names Curnberlarid, llighland Rim, and 

Coosa, of which the first two apparently correspond ·to the Cretaceous and Tertiary, 

though he does not say so explicitly. The 

conclusions concerning these peneplains have 

received wide acceptance, and it would be 

out of place to discuss their status in a report 

on Mississippi. 

In the vicinity of Iuka, ·in the northeast 

corner of Mississippi, the divide tops average 

perhaps 650 feet above the sea and are thus 

1 Hayes, C . . W., Physiography of the Chattanooga district: U. S. 

Geol. Survey Nineteenth Ann. Rept., pt. 2, pl. 2, 1899. 

2 Hayes, C. W ., and Campbell, M:. R., Geomorphology ofthe southern 

Appalachians: Nat. Geog. Mag., vol. 6, pis. 5, 6, May, 1894. 

a Hayes, C. vV ., op. cit. 
152 SHORTER CONTRIBUT'IONS T'O GENERAL GEOLOGY, 1917. ' 

not far from: alignment with the slope of the 

Tertiary peneplain above referred to . . As a 

matter of fact, however, between 10 and 25. 

miles to ·the northeast the divides of to-day rise 

somewhat abruptly to 1,050 feet, and farther 

northeast the rise is again very slight. Thus 

the divides in south-central Tennessee fail to 

accord with the described slope of the Tertiary 

.or Highland Rim penephiin. To the west they 

hold their altitude or decline very gently to 

600 feet at the border of the somewhat lower 

area of :Mississippi River terraces 25 miles east 

· of Memphis. To the south · they decline 350 

feet within 80 miles, the altitude of those near 

West Point being · only about 300 feet. The 

decline is not regular but is relatively steep to 

the belt underlain by the nonresistant Selma 

chalk. . For example, the divide on which Guntown, 35 miles southwest of Iuka, is built has 

an altitude of about 350 feet. This same belt 

of weak rocks is, however, over 500 feet high 

west of Iuka, suggesting two stages of erosion·. 

South-southwest of Iuka, along the main divide 

between :Mississippi and Tombigbee rivers, and 

southward to the latitude of Natchez, or fully 

250 miles, the surface ranges from 450 to 600 

feet in altitude, showing from place to place a 

response to varying rock hardness and perhaps 

reoording substages in erosion and slight warping. In other words, the uplands of :Mississippi 

seem to show remnants of several plains, all of 

which are nearly horizontal and lie below the 

uplands of the adjoining Interior Lowlands subdivision of the Appalachian province and most 

of which, at least, have . not sufficient northeastward rise to meet the "Tertiary peneplain" 

of Tennessee, unless they have undergone a 

somewhat sharp upwarp, so as to rise 400 feet 

in 25 miles. 

HIGHLAND RIM . PENEPLA!N. 

assumption that the-uplands of Mississippi are 

not of the same age as those of the adjoining 

portion of the Appalachian province seems warranted, and this assumption is verified by the 

fact that ' the divides near Waynesboro show 

some degree of accordance with the tops of the 

monadnocks near Iuka, . suggesting that these 

two groups of features may be . equivalent in 

age and may owe their difference in size and · 

form to the difference in · underlying rna terials. 

East and south of Waynesboro, Tenn., .there 

are some rather large and flat upland areas 

that are no doubt remnants of the plain which 

Hayes called the Highland Rim peneplain, and 

apparently considered identical with the Ter- . 

tiary peneplain that he and Campbell had 

described three years before. One remnant 

is a flattish . divide area of about 40 square· 

miles, from 1 to 5 miles wide and about 22 · 

miles long, all of which ·is between 1,000 and 

1,080 feet above sea level. The crest of the 

,north end of this divide averages about 1,065 

feet above sea level and that of the south end 

~bout 1,005 feet; in other words, the divide 

slopes southwestward at the rate of about 3 · 

feet to the mile for 20 miles. 

In Mississippi, 45 miles southwest of · th~s 

area, is a monadnock whose t~p is almost 800 

feet above the sea. If the divide south of 

Waynesboro, with its slope of 3 feet to 'the mile, 

were extended to this hill it would lie 870 feet 

above the ·sea. As, if other considerations 

balance, the smaller the remnant of a peneplain 

thf\ lower is its altitude, it may be that the two 

crests are to be correlated, and this possibility 

is strengthened by one or two remnants of 

intermediate height-for example, one 3 miles 

southeast of Riverton, Ala., whose top is 850 

feet above the sea. It is also only natural 

that the peneplain should be found to slope 

continuously in a southwesterly direction 

Not only would the upwarp first referred to toward the sea and the master drainageline. 

be called for if the general uplands of :Mississippi ·In view of .the presence of a large stream 

are to ·be correlated with the Tertiary pene- (the Tennessee) in this region, it is remarkable 

plain, as described, or with the Highland Rim, that the distance between the remnants 

as it exists to-day, but also a downwarp a little described is not greater. They are so close 

farther to the northeast, for the slope of the together and so similar in altitude that it 

"Tertiary peneplain" is only one-third as great must be inferred either that they are all remas this rise, and the crests of the present divides . nants of the same surface or that the larger 

in the vicinity of Waynesboro, Tenri., 40 miles . and relatively higher ones near Waynesboro 

northeast of Iuka, :Miss., are still more nearly belong to a somewhat older surface. 

horizontal and 400 feet higher than most of the If a broader area is considered it is found 

divides of northeast~rn :Mississippi. Hence t4e that the flat near Waynesboro extends inter-
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPPI. 153 

ruptedly northeastward 40 miles, or nearly 

to Columbia, holding the same altitude of a 

little over 1,000 feet; indeed, it may be carried 

to Duck River Ridge, 10 or 12 miles north of 

Columbia, whose crest is also between 1,000 

and 1,050 feet above the sea. East of this 

ridge the surface rises gradually for at least 15 

miles, to a point where it reaches 1,150 feet, 

and it seems to have a general eastward rise 

beyond that point. However, in the Hollow 

Springs quadrangle, 40 miles east of Columbia, 

where itis well developed and preserved, it has 

a southeastward slope from 1,200 or 1,300 

feet to about 1,100 feet within 15 miles. To 

the north the old flat is interrupted by the· 

Nashville Basin, the bottom of which Hayes 1 

correlated with a peneplain in Georgia that he 

called the Coosa. 

From these facts it is evident that the Highland Rim is _so high and so nearly horizontal 

that if projected south-southwestward it would 

inklrsect nothing in northeastern Mississippi 

but would lie slightly above the tops of the 

monadnocks in that region. _ If extended still 

farther it would likewise lie just above the tops 

of the highest hills in Union and other counties, 

and at Thackers Mountain (600 feet), 70 miles 

southwest of the 800-foot hill near Iuka, it 

would lie at 660 ·feet. Other intermediate 

hills, however, suggest that the slope of 3 feet 

to the mile is slightly reduced in Mississippi, 

so that at Thackers ~1ountain the position of 

the' old plain is perhaps 700 feet above the sea, 

this hill, like others of the monadnocks, having 

been worn down 100 feet or so more than the 

larger remnants in Tennessee. 

Still farther south the old plain seems to be 

traceable in the tops of the highest hills as far 

as the latitude of Jackson, a short distance 

south of which it is ·apparently covered by 

strata of Pliocene age, at an altitude of about 

4 70 feet. However, as the Pliocene overlaps 

somewhat it is possible that this old surface 

lies below the Miocene. The tracing is a little 

uncertain because of the lack of topographic 

maps, the poor preservation of the features 

representing the old plain, and the comparatively slight difference in· height between this 

plain and younger and lower upland plains; but 

two features relieve a large part of the uncertainty. One is the comparatively strong 

-contrast in form between the monadnock-like 

1 Hayes, C. W ., op. cit., pl. 2. 

remnants of ·the old surface and the much 

broader remnants of younger plains, and the 

other is the apparently uniform response to 

erosion by the numerous ferruginous sand 

member~ of several formations . . If no error 

has been made in tracing,· the average slope 

of the old surface in Mississippi is 2 feet to 

the mile for 200 miles. Owing to warping, 

however, the slope is not regular but apparently ranges from 3 feet to the mile to horizontality, or even a slight reversed slope here and 

there. 

COOSA PENEPLAIN. 

If the old surface represented by the tops of 

monadnocks in Mississippi is the Highland Rim 

peneplain, one would expect to find remnants 

of the younger Coosa peneplain in some of the 

lower hilltops. Correlation is somewhat un-· 

certain, because the distance from the Mississippi region to known remnants of this surface is greater than to the type region of the 

Highland Rim peneplain. It seems possible 

that the Coosa plain is compound and that its 

members are equivalent to the two or three 

upland plains of Mississippi that lie lower than 

the tops of the monadnocks. 

According to Hayes z peneplains may be correlated by continuous tracing, by noting 

similarities in degree of dissection, by observing 

coincidence of projected plains, and by determining recent drainage _ changes. To this list 

may be added observations of relation to other 

peneplains. Apparently the Coosa peneplain 

can not be traced continuously into Mississippi. 

Its degree of dissection would presumably be 

different in the "region under consideration from 

that in the type locality, because the underlying materials are very different and also 

because of a different arrangement of principal 

drain.age lines. The regions are too far apart 

to use coincidence of projected plains as a 

criterion, and no recent drainage changes seem 

to help in correlation. 

In Mississippi the next to the oldest · peneplain of which remnants are preserved lies 

a'Qout 100 feet below the tops of the widely 

spaced monadnocks, and if they have been 

wor:ri down 100 feet more than larger remnants 

its position is about 200 feet lower than that of 

the Highland Rim. On the other hand, it 

lies from 100 to several hundred feet above 

the present vall-ey bottoms, which have ap2 Hayes, q. W ., op. cit., p. 25. 
154 SHORTER CONTRIB.UTIONS 'l'O GENERAL GEOLOGY, 1917. 

proximately adjusted gradients, and it is 

maturely dissected. It thus resembles the 

Coosa peneplain in being next below the Highland Rim peneplain, in lying considerably 

above present graded valley floors, in being 

much dissected, _ antl in being the principal if 

not the only peneplain between ·the Highland 

Rim and the present valley floors. It differs 

from the Coosa plain in being somewhat more 

dissected and in being apparently one of about 

three that are younger than the Highland Rim. 

The greater dissection may be explained by 

more yielding materials. The Coosa plain is 

decidedly undulating if not rough, and it seems 

possible if not probable that it will be found to 

be compound. If so, its divisions may correspond with plains later than the Highland Rim 

lying -lower than the tops of monadnocks in 

northern Mississippi. -

Thus it · seems possible to determine the 

probable age of certain peneplains in Mississippi 

from evidence found within the State, and this 

forms a basis for revising and clarifying ideas 

concerning the age of Appalachian peneplains. 

It is recognized, however, that the data are not 

conclusive. 

WARPING OF PENEPLAINS. 

The peneplains , of northern and central 

Mississippi lie nearly horizontal, and yet all of 

them have suffered SOUle warping; originally 

each had no dou"Qt a slight general inclinati,on 

in some direction between . west and south. 

Their present slopes are in the same quadrant, 

but the directions of slope of some have ap-

- parently been shifted a little, and the amount 

of slope :of some has been increased and of 

some diminished. In general, the younger the 

plain the gentler is its present inclination, · and 

a considerable part of the deformation seems 

to have taken place in Pliocene time. 

The Paleozoic floor slopes about 30 feet to 

the mile; the plain at the base of the Tertiary 

about 20 feet to the mile; the slope of one at 

the top of the Eocene and others buried in the 

Eocene is _ no doubt considerably less than 20 

feet to the mile. Thus the slope of _successive 

buried plains gradually decreases toward the 

top of the geologic time scale. The slope of 

the top of the Oligocene averages only about 

2 feet to the mile, and still youn,ger peneplains 

seem to have average slopes of less than 2 feet 

to the mile. 

Next to the general southwestward tilting 

of the plains and the fact that the older the 

plain the _greater the .slope, the most ·striking 

feature of their warped form consists in the 

decidedly steeper average _slope of the older 

plains south of a belt of counties in th~ latitude of Vicksburg. The downward bend does 

not follow a sharp line but is irregularly developed. On the whole, its course trends 

east-southeastward from Jackson. For the 

older plains it inclines more to the southeast, 

and for the younger plains to the east. The 

slopes of the plains continue to increase southward, and at the present coast even some of 

the Pliocene -buried plains are tilted as much 

as 25 feet to the mile. _ 

~ ot only do the plains slope steeply in the 

south end of the State, but in the centr_al part 

they seem to have been warped i:q_ the opposite 

direction, so that north of Jackson their original gentle seaward and riverwar·d slope has 

been reduced _ to zero or a reversed slope. So 

far it has not been possible to determine the 

details of the warping. Some features suggest that a principal axis of uplift runs from 

Natchez to the northeast corner of the .State, 

and ' another from Mobile northeastward, and 

other features suggest an east-west axis through 

Vicksburg and another through Natchez. 

Perhaps the warping has followed all these 

lines at the same time or at different times. 

Determin~tion must await the preparation of 

topographic maps. _In any case the evidence 

that some of this warping occurred in Pliocene 

time seems. convincing, for both peneplains 

andquasipeneplains, including those which slope 

down into Pliocene deposits, seem to be warped 

upward around Jackson, and features of terraces and the drainage ·confirm the inference. 

TERRACES. 

GENERAL FEATURES. 

The presence of several ancient and high 

gravel terraces; principally along the Mississippi, the deep erosion of these terraces, and 

some other reasons for regarding them _as 

Pliocene have been referred to illnder "Sedimentary record." Apparently there are four 

main Pliocene terraces. All of them are now 

discontinuous, but on account of the facts 

that the terrace remnants are parts of ancient 

valley floors which were evenly graded, and 

that they have not since suffered very great 
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPPI. 155 

deformation, they can be classified and correlated roughly, and if topographic maps were 

available they could no doubt be traced with 

a good degree of certainty. 

The scattered remnants of the terraces were 

followed southward from Illinois through 

Tennessee, Kentucky, and western Mississippi 

to Vicksburg, where they were found to 

broaden and swing abruptly to the east 

across the State and continue into Alabama. 

After a conference with G. C. Matson/ who 

had been working on the late Tertiary deposits of the Gulf coast, it was decided . to 

name the four main terraces as described below and illustrated in figure 24. 

BROOKHAVEN TERRACE. 

The Brookhaven terrace is broad and well 

preserved around Brookhaven, where it now 

lies nearly 500 . feet above the sea. On th~ 

-north it rises gradually for 35 miles to the 

FEET Brookhaven pla in 500 

400 

300 

200 

100 

0 

Horizontal scale 10 20 30 40 MILES 

-500 

Thus• the Brookhaven terrace, or plain, as 

Matson has called its seaward portion, is fully 

60 miles wide and rises northward from 

about 450 feet to more_ than 550 feet, perhaps 

to 600 feet, and then declines to some unknown 

altitude greater than 450 but probably not 

mo:J;'e than 5oo feet. It has been so severely 

deformed and eroded that present information is not sufficient to justify a statement that 

it is not compound. Relative to lower terraces, it is much broader in the east-west 

coast belt than along the Mississippi in the 

central and northern parts of the State, and 

this may be due simply to a difference in resistance of underlying materials, but differences in the process of development n1·ay also 

have played a part, and differences in destructive processes have almost certainly had 

a notable effect. 

North of Vicksburg and Jackson, for the 

width of a county or two, no remnants of the 

FIGURE 24.-Diagrammatic cross section of Pliocene deposits and profile of Pliocene t erraces in the south end of Mississippi. 

southern parts of Hinds and Rankin counties, 

where, notwithstanding the fact that it has 

been severely eroded, its scattered remnants 

still reach 550 feet above the sea. That this 

terrace or some similar gravel-formed surface 

must have once ·extended 20 or 30 miles still 

farther north is indicated by the gravelly soil 

and subsoil of the higher knobs in that belt. 

These knobs are all lower than the remnants of the terrace south of Jackson, apparently for two reasons-the easy erodibility of the Vicksburg and Jackson formations, which underlie this district, and the fact 

that the horizon of the original surface of 

the terrace is lower because of warping than 

in , the vicinity of Star and other places south 

of Jackson. The warping is inferred from the 

position of several plains and terraces but 

particularly from t4at of the younger terraces, 

which are fairly well preserved west and northwest of Jackson. 

1 Matson, G. C., op. cit., pp. 180-186. 

Brookhaven terrace are now known, though 

pebbles tet down from the deposit forming it 

are numerous in many places. North of 

Yazoo County, however, where the underlying formations are the more sandy and resistant Claiborne and Wilcox, scattered remnants 

of the Brookhaven terrace are found as far 

north as Memphis. They seem to decline 

very gradually to the north, or upstream, from 

about 460 to about 430 feet above sea level. 

SARDIS TERRACE. 

The'· Sardis terrace is somewhat better pre- _ 

served than the Brookhaven but is still so 

badly eroded that in the lack of exact topographic data the identification of many of the 

supposed remnants is somewhat doubtful. 

It seems to be practically horizontal and from 

2 to 10 miles wide from Sardis, where it lies 

nearly 400 feet above the sea, to Durant. 

Between Durant and Vicksburg, where no _ 

part of the Brookhaven terrace'remains, there 
156 SHORTER CONTRIBUTIONS TO GENERAL _GEOLOGY, 1917. 

are a few remnants of the Sardis terrace. A 

·few miles southeast of Vicksburg the _terrace 

lies a little more than 400 feet above the sea, 

and east of Natchez it. reaches nearly 450 feet, · 

is 30 to . 40 miles wide, and is fairly well preserved. To the east it becomes narrower and 

slopes to the e~st and south. 

· CANTON TERRACE. 

gentle than that of the present flood plain. 

However, the divergence of th~ two is not 

uniform. 

WARPING OF TERRACES. 

Although many of the terrace ·tops are undoubtedly parts of ancient flood plains, most of 

them differ in gradient from the present flood 

plains of the same streams. On the whole they 

have a more gentle slope, but in some parts of 

In the vicinity of Canton, Miss., there are the State they seem to slope upstream instead 

some very broad, rather flat, upland areas, of down, and these upstream slopes can be acunderlain by sandy clay with gravel here and counted for only by deformation. -

there, at an altitude. of somewhat less than !J.'he Brookhaven terrace seems to be warped 

300 feet above the sea, evidently remnants of a upward as much as 200 feet just south of Jackterrace. To the north the terrace seems to son, where its position reaches 550 feet. Inbe nearly horizontal· or to ris~ very gently to deed, it seems to slope away from this district 

the Tennessee line. To the south the remnants in all directions, but most steeply' to the west 

rise to an altitude of about 370 to 380 feet at a and south. Fifty miles to the northeast it is 

point east of N'atchez. Along the Mi~sissippi · 60 or 70 feet lower. To the east, near. the 

this terrace ranges generally from 1 mile to 10 Alabama line, it is over 100 feet lower, and 

miles in width, though here and there it seems according to Matson 1 this slope continues 

to have been cut away by the lateral swing of across Alabama. Appa,r:ently, however, anthe river. Unlike the older terraces, it seems other and smaller upwarp iE! located north of 

to be fairly well developed along some of the Mobile. Fifty miles south of Jackson the terlarger tributaries, particularly the Big Black. race is ·more than 75 feet lower. To the west 

LOXLEY 'EERRACE. 

The Loxley terrace lies generally 40 to 80 

feet below the Canton terrace, and its general 

slope is slightly greater, or more nearly like that 

of the present·flood plains of the Mississippi and 

other large rivers. In the northern part of the 

State it lies 275 to 300 feet above the sea, or 

100 feet above the present flood plain. To. the · 

south it declines gradually at about the same 

rate as the present flood plain to Yazoo City, 

where its surface buried under the loess is 

about 250 feet above the s.ea. · From Yazoo 

City to Vicksburg it seems to be about horizontal and thus its distance above the present 

stream increases. Farther south · its altitude 

increaSes somewhat rapidly downstream to 

more than 300 feet at a point east of Natchez. 

·Apparently a terrace equivalent in age was well 

developed and is fairly well preserved on 

Pearl, Big Black, Y alobusha, and T~llahatchie 

rivers and on the Tom big bee, .·in the eastern 

part of _ the State. The terrace rises up each 

one of these streams, though its height above 

the present flood ·plain gradually decreases upstream-in other words, on these streams the 

terrace has a downstream slope which is more 

also it declines to about 380 feet in Louisiana. 

The site' of maximum uplift of the later terraces seems to be successively farther and farther southwest toward ' Natchez, and the 

amount of uplift less and less. Perhaps, however, the actual amounts of uplift of each terrace did not differ greatly, but, the effect being 

cumulative, the oldest terrace now shows the 

greatest deformation. . The re~ulting slopes 

have been still further modified by an uplift 

of the ear.liest Pleistocene terrace in the vicinity 

of Natchez.2 

DRAINAGE MODIFICATIONS. 

MISSISSIPPI RIVER. 

During Pliocene time the Mississippi or some 

other large stream· followed the general course 

of the present Mississippi, in the region under 

discussion, as . ·can· be inferred from the remnants of its old deposits and valley floors 

which are preserved in the form of terraces. 

N ev:ertheless the stream differed in several 

.noteworthy respects from the Mississippi of 

to-day. 

1 Matson, G. C., op. cit., p. ISO: 

2Shaw, E .. W., The mud lumps at the mouths of the Mississipri: 

U.S. Geol. Survey :frof. Paper 85, p.IS, 1914. 
PLIOCENE IUST'QRY OF NORTHERN AND CENTRAL MISSISSIPPI. 157 

In early Pliocene time its mouth was far 

· above the site of its present mouths-probably farther north than Natchez, which is 375 

miles by water above the mouths-for (1) the 

general effect of bringing so huge a load of 

sediment as it carries to the sea is to build the 

coast forward, whether or not moderate warping is in progress, though in case of rapid 

downwarping the coast might migrate landward; (2) no Pliocene river ,deposit is known 

south of the southwest corner of Mississippi; and 

(3) a Mississippi River terrace deposit believed 

to be early Pliocene spreads eastward across the 

State 100 miles north of Natchez, indicating 

either a seashore at this latitude or the northern 

boundary of a great and continuous area of land 

sedimentation, for the deposit caps the highest 

divides; and its landward edge, though now 

much frayed, was apparently once straight or 

gently sinuous. 

The volume of the Mississippi was evidently 

much smaller in the Pliocene epoch than now, 

for an extensive area is kno-wn to have been 

added to the northern part of its basin by the 

glaciers of Pleistocene time, and certain topographic features in the upper half of its basin 

including the youthful form of its valley, seem 

to indicate that this added area is consider~ 

ably larger than has generally been supposed. 

'l'he coarseness of the Pliocene deposits of the 

river may also be an indication of lesser volume. 

If its volume was less its gradient was presumably steeper, as the coarse deposits also suggest; and if the gradient was steep~r the inferred deformation which has brought the deposits in places to a horizontal attitude or even 

given them an upstream slope was greater 

. than if the slope had been as gentle as at 

present. However, the gradient of the lower 

half of the Mississippi is not extremely gen tie 

to-day, for the lower Amazon, the lower Nile, 

and even the lower Ohio have gradients as 

slight or slighter. 

The breadth of the Mississippi Valley was 

apparently not so great in Pliocene time as 

to-day, for the terrace remnants of its Pliocene valley floor are small and have evidently 

been severely worn by lateral swings of the 

river. In very few places are all four of the 

main Pliocene terraces represented, and in 

some places all have been worn away. 

In one or several parts of the Pleistocene 

epoch the Mississippi flowed on the west side 

of its valley, ·at times whipping against the 

bluff at Little Rock, and the Ohio joined it 

at some point below Helena, Ark., perhaps 

s'outh of Greenville, :Miss., Crowleys Ridge 

being the divide between the two rivers. . It 

appears probable that a similar arrangement 

existed in Pliocene time, but direct evidence is 

lacking. 

PEARL RIVER. 

The course ,of Pearl River 'lies for the most 

part in the region of the coastal Pliocene deposits, and although precise data concerning 

the form of the valley and the profile of the 

stream are scant it is evident that some anomalous features are displayed in the vicinity 

of Jackson. These features seem to be explained by the upwarps at Jackson and to the 

southwest. In the first place its course has a 

peculiar westward bend at Jackson and its 

main tributaries come from the east, suggesting 

that one or more of its main western tributaries 

have been captured and diverted by the ·Big 

Black. Second,' the smaller southern tribu~ . 

taries of the Big Black are pushing the divide 

close over to the Pearl, whose channel is from 

50 to 100 feet higher than that of the Big 

Black. Third, in the vicinity of Jackson the 

Pearl has a low gradient, a very meandering 

channel, and a swampy flood plain, whereas 

the Big Black and also sections of the Pearl 

abov,e and below this part have a higher 

gradient, a more direct course, and a lesf:) 

swampy flood plain. · In the vicinity of Jackson the Pearl has the appearance of an aggrading stream, which is disproportionately small 

compared with its v~lley, yet it is 250 to 300 

feet' above sea level and the distance that its 

water hasto travel in getting to the sea is 100 

miles shorter than that traveled by the water 

of the Big B~ack. 

These facts suggest that the headwaters of 

the Big Black were once the western headwaters 

of the Pearl. Whether the diversion took place 

near Canton or at some place farther upstream 

·has not , been ascertained. The remarkable 

width of the Canton terrace and the much 

lower general altitude and more subdued surface features around Canton, compared with 

the region around · Jackson, shown on the 

Jackson topographic · map, suggests that the 

stream capture may have occurred in that 

vicinity, and, that the time was late. Pliocene 

or later. 
158 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. 

BIG BLACK RIVER. 

. In addition to the apparent enlargement of 

its drainage basin one other feature of th~ Big 

Black seems worthy of mention in a paper on 

the Pliocene history of the region. The divide 

between the Tennessee and the headwaters of 

Big Black, Yalobusha, Y ocona, and T~llahatchie rivers is well over toward the Tennessee, · 

the middle and upper portion$ of which are 

much more nearly in line with one of these 

Mississippi rivers than with the lower course of 

the· Tennessee.. On account of . this and other 

considerations Hayes and Campbell 1 have inferred, and many geologists have accepted the 

inference, that the Tennessee once had a southwesterly . course across Missis~ippi. They believe tb,.at "at the close of the Cretaceous cycle 

of erosion" a small river flowed westward 

. across northern Alabama and emptied into the 

sea in the northeast corner of Mississippi; that 

one or more of the head branches of this stream 

to indicate that when they were laid down 

many small streams (or distributaries of ·a few 

large ones) with shifting channels flowed in general southwesterly courses across Mississippi. 

Presumably the Eocene sediments of Mississippi came from the adjoining portion of the 

Appalachian province, which includes .. t~e 

middle and upper parts of the present basm of 

the Tennessee and adjacent territory. There 

is hence reason for assuming that the drainage 

of most of the Tennessee basin in Eocene time, 

and perhaps also in Oligocene time, went sout?-

westward a'cross western Alabama and J\!bssissippi. However, the Oligocene Vicksburg 

limestone and some of the Eocene Jackson 

marl indirectly indicate that at the time of 

their deposition.sand and silt from the southern 

part 'of the Appalachian province was not being 

deposited in the region of their occurrence 

(Mississippi and farther east). 

TOMBIGBEE RIVER. 

then captured some eastern Tennessee drainage Along the Tombigbee· there are somewhat 

that had been going to Mobile Bay; that upon extensive high terraces, particularly in the 

the withdrawal of the sea this stream followed vicinity ofWest Point, Miss., and to the souththe course of the Big Black to the Mississippi. east in Alabama; Beat Creek, a tributary of the 

The northward diversion of the Tennessee in Tennessee in the northeast corner of Mississippi, 

the northeast corner of Mississippi is de- has a strikingly gentle gradient and a broad 

scribed as having occurred in the early part of valley; the divide around the headwaters ofthe 

"the present cycle," a~ter "the Lafayette de- Tombigbee, in the northeast corner of the State, 

pression," which "QCcupied the closing epoch is only 15 or 20 miles 'from the Tennessee; and 

of the Tertiary cycle." 2 northeast of Iuka the Tennessee flows over a 

Although many . details of the ;history of the rocky s{wa1 in a very narrow valley. These 

Tennessee as set forth by Hayes and Campbell facts suggest that the .Tennessee may have 

appear to need modification, numerous facts emptied down the Tombigbee Valley in Plioseem to support the more essential parts of their cene tim~, but if so some parts of the old cour8e 

postulate. The ·Tennessee surely did not flow of the stream have not been found. · It seems 

down the course of the Big Black in Pliocene rather unlikely that Bear Creek occupies a part 

time, for no high terraces seem to be left along of the. old course, for its valley, though wide, is 

the Big Black as a record, and there is no scarcely wide enough for the Tennessee, and if 

abandoned valley between the . two streams. it was cut by a large stream that is now diverted 

Certainly the Tennessee did not flow near Iuka · the diversion must have occurred in Quaterand Tupelo, as shown in their figures. For nary time, for the valley is broad to its bottom. 

similar reasons it seems also certain the Tennes- As Lowe a has pointed out, however, the 

see did not flow down the Y alobusha, Y ocona, higher part of the divide between the major 

or Tallahatchie valleys·in the Pliocene epoch. streams is in some places ''a narrow ridge'' a 

That it did not flow down the Tombigbee, few hundred yards wide and perhaps 50 feet 

however, or even that it did not follow one of high, and it is probable that at a point 4 miles 

the other valleys mentioned, in some earlier below Paden Mackeys Creek, a tributary of the 

epoch, is not clear. The Eocene deposits of Tombigbee, is as low as the Tennessee at the 

Mississippi seem to be largely streani hiid and 

1 Hayes, C. W ., and Campbeli, M. R ., op. cit. 

2 Idem., p. 119. 

a Lowe, E. N.,A diversion scheme to prevent overflows of the Mississippi and to establish a navigable waterway from Mobile Bay to the Ohio 

River, p. 5, 1912. · 
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPPI. 

.A, "' 

~ 

~ 

91° 

32~----~~~~~~~~~-=~L-~~~~~~~~,4~-+~~~~~~rt---~~t---~-p ~ 

~ 

~ 

'\ 

159 . 

· , j 

FIGURE 25.-Sketch map showing shapes of drainage basins in Mississippi. Note particularly that the divide between Mississippi and Tennessee 

rivers is located far to till! east, and that the form of the drainage basin of the Pearl strongly suggests that the upper and middle parts of the 

Big Black basin formerly drained into it. 
160 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, l917. 

north boundary of the State. Lowe states 

that "the total distance * * * from the 

Tennesse~ "·River to··an ··equal•elevation on 

Mackeys' Creek is 29 miles," and the crest of the 

divide is: only about 200 feet above -low water 

on the Tennessee· and considerably less above 

high water. · -

The general shap~ of the drainage basins of 

Missis~ippi, whi~h seems to have been largely 

acquired in Pliocene time, is indicated rn 

figure 25. 

STRUCTURAL RECORD. 

What is· known of the structural record of 

Pliocene time in northern and central Missis.:. 

sippi has been largely outlined in the discussion 

of warped physiographic features. It consists 

of evidence of uplifts in the southwestern part 

of the State and perhaps also along a belt extending northeastward to the northeast corner 

and possibly another uplift whose axis lies in 

southwestern Alabama, affecting the southeast 

corner of the State. Stephenson 1 has found 

evidence of an uplift at Starkville, on the axis 

that is thought to run northeastward from 

Jackson, and such an uplift may have occurred, 

as there seem to .have been 'other movements 

along this axis in Pliocene time. 

The Pliocene uplift along the MemphisCharleston axis suggested by Shaler; 2 described 

by McGee/ and accepted by Hayes and Campbell,4 does not seem to have affected either the 

surface features or the deposits of Mississippi,. 

though it is described as crossing the northern 

part of the State. · 

That a surprisingly large amount of ·deformation of the strata of Mississippi probably occurred in Pliocene or early Pleistocene time is 

~hown by the comparatively much disturbed 

attitudes of the Pliocene deposits and the surface features that are buried -in them or for 

other reasons ·are believed to . date from the · 

Pliocene epoch. 

Hilgard 5 and Crider 6 call attention ·to a 

northward, dip of Eocene and Oligo?ene strata 

1 Stephenson, L. W ., unpublished notes. 

2 Shaler, N .. S., On the causes which have. led to the production of Cape 

Hatteras: Boston So·~. Nat. Hist. Proc., vol. 14, pp. 110-121, 1871. 

a McGee, W J, The Lafayette formation: U.S. Geol. Survey Twelfth 

Ann. Rept;, pt. 1, p. 403, 1891. 

•Hayes, C. W., and Campbell, M.R., op. cit., p. 81. 

o Hilgard, E. W ., Geology and agriculture of Mississippi, p. 128, 1860. 

6 Crider, A. F., Geology and mineral resources of Mississippi: U. S. 

Geol. Survey Bull. 283, p. 34, 1906. 

between Jackson and Canton. Veatch 7 describes a fault with a downthrow on the north 

of about 600 feet that extends from Texas 

through. southern Arkansas and northern 

Louisiana to a point 15 or 20 miles north of 

Vicksburg and forms a continuation: of one 

-in Texas called by Hill .

8 the Red River fault 

and described as having a similar displacement; 

but later work by Stephenson 9 throws doubt 

on · the existence of this fault ill at least a 

part of its ·course. Another structural feature, 

''the Angeline-Caldwell monoclinal flexure, '' is 

described by Veatch as extending southwestward from the same point north of Vicksburg. 

·· However, on account ·of the fact that an 

uplift of the southwestern part of Mississippi is . 

implied by the physiographic features, the 

writer recommended . that an area around 

Vicksburg be examined 'with reference to its 

possibilities of yielding oil and· gas. A survey 10 

was made and the hard rocks were found to 

be bent upward, thus confirming the inferences drawn from surface ·features.- The 

map showmg the structure · of the hard rocks 

gives somewhat more detail than can be inferred from the surface features in the lack of 

topographic_ maps, but still it shows· less 

accurately the movements that have affected 

the rocks, because it includes the effects of 

pre-Pliocene warping and also those of all 

later movements together, whereas from the 

surface features something niay be inferred as 

to the time, place, and _ effect of each movemerit. 

CONCLUSIONS. 

INTERPRETATION OF THE "LAFAYETTE FORMATION." 

In the opinion of the writer, the material 

called "Lafayette formation" in Mississjpp{ is 

the product neither of Pleistocene icy Roods 

from the north nor of a marine invasion; it 

is not a Pliocene blanket of waste from the 

Appalachians gradually spread over the State 

by streams; and it does ~ p.ot consist altogether 

7 Veatch, A. C., Geology and underground water resources ofnorthe~ 

Louisiana and southern Arkansas: U. S. Geol. Survey Prof. Paper 46: 

p; 68, pls. 36, 37, 41, 1906. 

s Hill, R. T ., Geography and geology of the Black and Grand prairies, 

Tex.; U. S. Geol. Survey Twenty-first Ann. Rept., pt. 7, p. 384, 1901. 

9 Stephenson, L; W ., unpublished notes. 

1o Hopkins, 0. B., Structure of the Vicksburg-Jackson area, Miss.: 

u. S. Geol. Survey Bull. 641, pp. 93-120, 1916 (Bull. 641-D). 
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPPI. 161 

of parts of pre-Pliocene formations, with their 

surface ;residuum. It is believed to be made 

up of unrelated or distantly related materials 

that have been erroneously .grouped together 

~nd to consist in the main of more or less 

modified parts of the underlying ·formations, 

including some residuum and colluvium, and 

of terrace deposits of Pliocene and Quaternary 

age. 

DIASTROPHISM. 

Position of surface at begi'[!Jning of epoch.-

The facts that the buried portion of the Pliocene surface is of gentle relief and that the 

tops of monadnocks and other remnants of 

plains are somewhat concordant in altitude 

suggest that at the beginning of the Pliocene 

epoch the surface of ~1ississippi was smoother 

than it is to-day. The coarseness of the 

stream deposits and the nature of the warping 

of the plains and for~ations suggest that at 

that time the surface of central and northern ~ss.issippi, though possibly lower than 

at present, had a considerable and somewhat regular westward and southwar.d slope 

toward ~ssissippi River and the Gulf. 

However, this surface, though perhap& lower 

with reference to sea level, was higher '\\-rith 

reference to the underlying rocks and possibly 

with reference to the earth's center; for it has 

not only suffered local upheaval but has been 

worn down by erosion and perhaps has sunk 

a little, owing to general earth shrinkage. 

Deformation.-The triangular area of which 

Jackson, Vicksburg, and Natchez form the 

corners has certainly been eleva ted in and 

perhaps after Pliocene time, and the place of 

maximum upwarp seems to have shifted southwestward during the epoch, for the deposits and 

plains are not only warped upward, but the 

earliest ones are uplifted most and the center 

of uplift is different for different plains and 

deposits. In addition there ·appear to have 

been a general east-west and a northeastsouthwest belt of uplift through Jackson and 

another region of uplift just east 'of the southeast corner of the State. The maximum 

amount of uplift seems to have been at least 

200 feet, for a terrace seems to rise in a downstream direction to that extent between Yazoo 

City and Star. The uplift seems to have been 

intermittent and to have occurred in four 

principal stages. The great breadth of the 

earliest Pliocene terrace and its height compared with the bordering divides suggest that 

the low relief of the beginning of Pliocene time 

lasted through perhaps a third or a half of the 

epoch before the first of the four uplifts 

occurred. The most pronounced result of all 

the movements is a great steepening of the 

seaward slope of strata and plains of all ages 

in the southern third of the State. Other than 

the depression of the coast region involved in 

this steepening, no downwarps are known to 

have occurred. 

EROSION. 

Weathering and local transportation.~The 

work of meteoric waters and of vegetation 

during the Pliocene epoch was evidently 

manifold. In addition to the main processes 

involved in the production of soil rains and 

consequent rills washed much of the in cohereD. t 

underlying sand and clay down slopes and 

dissolved and carried away much mineral 

matter, both above and below ground; gravity 

through the aid of wetting and drying and 

other agencies, including perhaps freezing and 

thawing, . pulled surface material downhill; 

wetting, aeration, and chemical processes 

weathered the material lying above ground 

water and transported iron oxide and other 

substances, both by solution and mechanically, 

a greater or less distance; and apparently much 

iron oxide that lies near the surface to-day has 

been concentrated downward from strata that 

were worn away in Pliocene time. 

Through transportation and corrasion.-Aside 

from the probably small amount of mineral 

rna tter that has been carried to the sea underground the removal of such ~atter from Mississippi has evidently been accomplished largely 

by streams, though no doubt some material 

has been swept out of the State by wind. The 

general work of erosion has been the gradual 

deepening of valleys, though apparently this 

work has been in places, particularly on the 

Mississippi, subjected to interruptions during 

which considerable deposits were laid down. 

Not only were valleys deepened, however, but 

divides were reduced both by mechanical and 

by chemical agencies. To . judge by processes 

now active the amount of rna terial carried 

away in solution was fully as great as that in 

suspension if not greater. Hence it must be 

assumed that all parts of the region that have 

been exposed since Miocene· t!me have been 
162 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 191'7. 

subjected to a continuous and vigorous process 

of reduction, perhaps to an. extent of 100 tons 

to the square mile each year.1 · It seems reasonable to assume, therefore, that the surface at the 

beginning of Pliocene time was at least 100 

feet above the highest hills remaining, to-day, 

and that much of it was lowered more than: 200 

feet in the Pliocene epoch. _ 

At apparently · four different times the nature of the erosive processes was 'so modified 

that plaihs began to · be formed, though the 

earliest one or two of these times may have 

been in the Miocene epoch. It seems possible 

that the deepening of valleys in Mississippi 

was checked at times when it was accelerated 

in adjoining provinces, for at such times in 

Mississippi through streams would probably 

-be overloaded with · material from their upper 

courses. In any case -erosion developed striking monadnock-like hills in certain sa:ndy 

areas. and cemented their tops with iron oxide. 

In the northeast corner of Mississippi an 

opportunity is afforded for tracing the peneplains of the Appalachain provmce southwestward into the Coastal Plain. A careful study of 

the surface features in and near this part of the 

State suggests that the Highland Rim peneplain; so well developed ill the adjoming portion of the Appala9hain province, is less 

ancient than has generally been supposed. It 

does not seem to be older than the beginning 

of the Pliocene but may be as old as early 

Miocene. A pre-Cretaceous peneplain, however, is apparently' represented by hilltops in 

and near the northeast corner of Mississippi, 

but this plain is preserved because for a large 

part of its existence it was buried beneath the 

Coastal Plain sediments and has 'only recently 

been exposed. There is also indication that a 

peneplain emerges from between the Cretaceous and Tertiary systems in Mi~sissippi and 

passes upward toward the ·northeast but 

slopes less steeply than the pre-Cretaceous 

plain, with the result that the two intersect. 

Both plains no doubt suffered considerable -

denudation in Pliocene time. The Miocene 

0) plain at the tops of the isolated hills rises 

even more gently to the northeast and intersects the other two plains. The still lower 

and younger plains are not yet satisfactorily . 

differentiated, b~t they are nearly horizontal : 

·1 See particularly data on the Pearl at Jackson .given in U.S. Geol. 

Survey Water-Supply Paper 234, p. 87, 1909. 

and, like the older ones, rise to the northea·st, 

each successive one more gently than the preceding and . each intersecting all the older 

plains: 

If the old surface represented by the tops of 

monadnocks is not the Highland Rim peneplain, it must be sli"ghtly younger7 and if so 

that peneplain must cross it and ·slope down _ 

under slightly older sediments. The lack · of 

any indication of such a relation lends support 

to the in terprett1tion that the monadnocks are 

really somewhat' reduced remnants of the 

Highland Rim peneplain. Moreover, if the 

seaward portion of this peneplain passes under 

Pliocene sediments, it must have been formed 

just before Pliocene time, and one piut was 

buried and another carved into monadnocks 

during Pliocene time. 

It seems evident that the present divides, 

which show a comparatively abrupt rise 10 to 

25 miles northeast of Iuka, do not belong to a 

surface of uniform age and origin, but that 

the surface farther northeast is the remnant 

of a plain which was mainly developed upon 

resistant cherty limestone of Mississippian 

(St. Louis and Fort Payne) age and which now 

has a gentle southwesterly slope to a line 

lying about 25 miles northeast of Iuka. Along 

this line the · Highland Rim peneplain intersects a more steeply sloping and ol~er planed 

surface which dips under Cretaceous deposits 

that reach sea · level 15 or 20 miles ·west of 

Iuka. The accordant crests of Mississippi, 

with the possible exception of the monadriock 

tops, evidently belong neither to the Highland Rim peneplain nor to the peneplain finished just before Upper Cretaceous- time. 

However, the -surface of the region when it 

became partly subm-erged in the Upper Cretaceous sea may have been little or no smoother 

thanit has been at.many times before and since. 

Drainage modifications.-The drainage modifications seem to have been continuous and very -

gradual rather than sudden. A portion of the 

Pearl seems to have been captured by the Big 

Black; but the other changes seem to have consisted in a gradual shifting of divides, which is 

suggested by drairiage patterns but can not be 

demonstrated because of lack of topographic-. 

data. Perhaps the inost striking feature of this 

class is the short distance between Tennessee 

River and the divide on th~ southwest side of 

its basin in Mississippi. 
PLIOCENE HISTORY OF NORTHERN AND CENTRAL MISSISSIPJ;>I. 163 

SEDIMENTATION. composition and extent and resemble the terSedimentation in valleys.-Not only did the race deposits of the Mississippi much more than 

streams of Mississippi considerably deepen their those of other streams, and that the surface feavalleys in the Pliocene epoch, but at the same tures consist of about four terraces parallel to 

·time, thoug?- not ~t a uniform rate, they depos- the coast suggesting in some respects the surited much sand and gravel in their valley bot- faces of uplifted compound deltas seem to sugtoms. Apparently, at four stages in particular, - gest marine conditions. On the other hand, the 

the Mississippi received more sand .and gravel facts that the terrace fronts are not well-defined 

than it could carry perhaps because of uplifts of . escarpments' that sea cliffs and beaches seem to 

the Appalachian or Ozark mountains, and as a be lacking, that Pliocene land plants grew at 

consequence it meandered widely, undercutting least as near the present coast a~ Perdido Bay, 

its valley sides and spreading sand and gravel Ala., and perhaps considerably farther south 

over its flood plain. Somewhat extensive than the present coast, that the stratification 

though much dissected remnants of the~e de~ and sorting seem to point to stream rather than 

posits are to be found to-day here and there ocean action, and that nowhere in these depos- -

along the valley side. The overloaded condi- its do there seem to be marine fossils strongly 

tion did not last long, for the deposits do not . suggest land deposition. 

seem tohave been much thicker than the ordinary alluvium along large rivers. Perhaps the 

four terrace deposits correspond to the four 

peneplains that are possibly represented in the 

divides; but it may be that at only two or 

three times of valley filling were plains perceptibly developed and that the older one or two 

peneplains are Miocene~ · 

Coastal sedimentation.-Whether at the beginning of Pliocene time the coast was at the 

northern limit of the Pliocene deposits or 

whether part or all of these sediments are land 

deposits are problems that have not been 

solved, though the balance of evidence seems 

to favor land deposition. The facts that the 

-northern boundary seems to have been a somewhat regular line, that the deposits cross interstream areas, that they are fairly uniform in 

CLIMATE AND LIFE OF THE EPOCH. 

What is lmown of the plants and animals that 

lived in Mississippi in Pliocene time is largely 

set forth in recent papers by Matson and Berry .

1 

The. only additional organic remains worthy of 

mention are petrified logs, such as are fairly 

common in the high terrace deposits of the Mississippi. The climate also seems to have left 

little record except the products of weathering, 

which seem to be in,distinguisha ble from those · 

of to-day. Perhaps some· of the erosion features were produced by changes in climate, but 

they seem more reasonably accounted for by 

deformation. 

1 Matson, G. C., The Pliocene Citronelle formation of the Gulf Coastal 

Plain: U.S. Geol. Survey Prof. Paper 98, pp.167-192, 1916. Berry, E. W ., 

The flora of the Citronelle formation: Idem, pp.193-208. 

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