Stratigraphic Notes, 1980-1982

GEOLOGICAL SURVEY BULLETIN 1529-H

Stratigraphic Notes, 1980-1982

CONTRIBUTIONS TO STRATIGRAPHY

GEOLOGICAL SURVEY BULLETIN 1529-H

Seventeen short papers deal with changes in 

Stratigraphic nomenclature: names adopted, 

revised, reinstated, or abandoned and ages 

of rocks changed

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1982
UNITED STATES DEPARTMENT OF THE INTERIOR 

JAMES G. WATT, Secretary

GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Library of Congress Cataloging in Publication Data

Main entry under title:

Stratigraphic notes,1980-1982.

(Contributions to stratigraphy) (Geological Survey bulletin ; 1529-H)

Bibliography: p.

1. Geology, Stratigraphic-Addresses, essays, lectures. I. Geological Survey (U.S.).

II. Series. III. Series: Geological Survey bulletin ; 1529-H.

QE75.B9 no. 1529-H 557.3s 82-600117 

[QE651] [551.700973]

For sale by the Distribution Branch, U.S. Geological Survey, 

604 South Pickett Street, Alexandria, VA 22304
CONTENTS

Note Page

1. Adoption of the name Hutchinson River Group and 

its subdivisions in Bronx and Westchester 

Counties, southeastern New York, by 

Charles A. Baskervi1le...........................HI

2. Carboniferous formations in central Oregon, by

Harold 3. Buddenhagen...........................Hi 1

3. New Paleozoic formations in the northern Kuskokwim 

Mountains, west-central Alaska, by. 3. Thomas 

Dutro, 3r., and Wi 1 1 iam W. Patton, 3r...........H13

^. New stratigraphic unit in the Wilcox Group (upper

Paleocene-lower Eocene) in Alabama and Georgia,

by Thomas G. Gibson .............................H23

5. Revision of the Hatchetigbee and Bashi Formations

(lower Eocene) in the eastern Gulf Coastal

Plain, by Thomas G. Gibson..................... .H33

6. Formation names in the Worcester area, Massachusetts, 

by Richard Goldsmith, Edward S. Grew, 3. 

Christopher Hepburn, and Gilpin R. 

Robinson, 3r ....................................H43

7. Stratigraphic names in eastern Massachusetts and

adjacent States, by Richard Goldsmith, David R. 

Wones, and Andrew F. Shride.....................H57

8. Mauzy Formation, a new stratigraphic unit of Permian 

age in western Kentucky, by Thomas M. Kehn, 3ohn 

G. Beard, and Alien D. Wi 11iamson...............H73

9. Signal Granite (Precambrian), west-central Arizona,

by Ivo Lucchitta and Neil Suneson...............H87

10. Adoption of names of certain members of formations 

in the Hamilton Group (Middle Devonian) of New 

York, by William A. Oliver, 3r..................H91

11. Correlation of Eastford Gneiss with Canterbury Gneiss,

eastern Connecticut, by Maurice H. Pease, 3r....H95

12. Revision of Upper Cretaceous nomenclature in Montana 

and South Dakota, by Dudley D. Rice, George W. 

Shurr, and Donald L. Gautier....................H99

HI
IV

Note Page

13. Chandler Bridge Formation--A new Oligocene stratigraphic unit in the lower coastal plain of South 

Carolina, by Albert E. Sanders, Robert E. Weems, 

and Earl M. Lemon, 3r ..........................HI 05

14. New members of the Madison Limestone (Devonian and 

Mississippian), north-central Wyoming and 

southern Montana, by William 3. Sando..........H125

15. Huntersville Chert (Devonian) extending from 

southwestern Virginia into southwestern 

New York, and its Bobs Ridge Sandstone Member, 

by E. G. A. Weed...............................H131

16. Nealmont Limestone (Middle Ordovician) extending 

from southwestern Virginia into southwestern 

New York in the central Appalachians, by 

E. G. A. Weed..................................H135

17. Recognition and formalization of the Pliocene "Goose 

Creek phase" in the Charleston, South Carolina, 

area, by Robert E. Weems, Earl M. Lemon, 3r., 

Lucy McCartan, Laurel M. Bybell, and Albert E. 

Sanders........................................Hi 37
ILLUSTRATIONS

Figure Page

1. Location map showing the relation of the study area, 

Manhattan Prong of New England upland, to the State 

of New York and a sketch map outlining the known 

outcrop area of the Hutchinson River Group in 

Westchester and Bronx Counties...................H2, H2a

2. Diagrammatic stratigraphic column of the Hutchinson

River Group, Bronx and Westchester Counties, N.Y......H5

3. Map showing Carboniferous formations in central

Oregon: a correction ...............................H12

k. Sketch map showing areas of outcrop of Nixon Fork

and East Fork terranes, northern Kuskokwim Mountains, 

west-central Alaska..................................H14

5. Generalized columnar section of lower and middle

Paleozoic rocks, northern Kuskokwim Mountains, westcentral Alaska.......................................H15

6. Locality map and cross sections of Baker Hill

Formation, Ala. and Ga...............................H24

7. Section of south wall of Lynn Griffin mine //I, Henry

County, Ala., type locality of Baker Hill Format ion..H25

8. Correlation chart showing age relations of units of

late Paleocene and early Eocene age..................H28

9. Core-hole section at Highland Park, Henry County, 

Ala., lithologies of the farthest downdip part of 

Baker Hi 11 Formation.................................H30

10. Index map showing locations of Hatchetigbee and Bashi

sections, eastern Gulf Coastal Plain.................H35

11. Correlation chart showing contact relations of 

Hatchetigbee and Bashi Formations, eastern Gulf 

Coastal Plain........................................H37

12. Map showing generalized geology of the east flank of 

the Merrimack synclinorium, Massachusetts and New 

Hamp shire.................... ........................H^ ^

13. Correlation chart of layered-rock units in the east

flank of the Merrimack sync 1inorium, Massachusetts and 

New Hampshire........................................H46
VI

Figure Page

14. Sketch map of major geologic features of eastern

15. Correlation chart showing the nomenclature of Kehn

and others (this report) and of previous reports.....H75

16. Index map of the western Kentucky coal field, type 

area of the Mauzy Formation, and location of the 

stratigraphic test holes .............................H76

17. Geologic map showing area underlain by the Mauzy

Formation, western Kentucky ..........................H77

18. Map of known outcrop areas of Signal Granite, westcentral Arizona......................................H88

19. Index map showing distribution of Canterbury Gneiss

in the Eastford, Hampton, and Spring Hill quadrangles, 

New York.............................................H96

20. Correlation chart of Upper Cretaceous rocks in eastcentral Montana and northwestern South Dakota ......H100

21. Map showing areal distribution of Mosby Sandstone

Member, north-central Montana .......................HI 01

22. Electric log showing presence of several sandstones

in Mosby Sandstone Member, north-central Montana....H102

23. Map showing areal distribution of Shannon Sandstone 

Member and Groat Sandstone Bed, Montana and South 

Dakota. .............................................H103

24. Index map showing 7 1/2-minute quadrangles and known 

subcrop areas of the Chandler Bridge Formation, 

eastern South Carolina..............................HI 06

25. Diagrammatic cross section of the paleontologic 

excavation site designated as the type section of 

the Chandler Bridge Formation, lower coastal plain 

of South Carolina...................................HI08

26. Photograph of type section of the Chandler Bridge 

Formation, lower coastal plain, South Carolina, 

showing the basal contact with the Ashley Member of 

the Cooper Formation and the three beds composing 

the Chandler Bridge Format ion .......................HI 12

27. Photograph of view from above of the section shown 

in figure 26, showing the top surface of the Ashley 

Member of the Cooper Formation, lower coastal plain, 

South Carolina..................................... .HI 13
VII

Figure Page

28. Index map of north-central Wyoming and southern 

Montana showing mountain ranges and basins where 

new members of the Madison Limestone are recognized 

and location of type sect ion ........................HI 26

29. Stratigraphic diagram comparing new nomenclature of 

Madison Limestone, north-central Wyoming and southern 

Montana, with previous nomenclature and ages of the 

member s.............................................HI 27

30. Map showing the main subsurface extent of the 

Huntersville Chert, southwestern Virginia to 

southwestern Pennsylvania...........................H132

31. Location of type section and isopach map of the Goose

Creek Limestone in the Charleston, S.C., area.......HI 38

32. Type section of the Goose Creek Limestone in the

Charleston, S.C., area ..............................HI 39

33. Structure contour map of the base of the Goose Creek

Limestone in the Charleston, S.C., area.............HI 43

34. Map showing known distribution of Pliocene localities 

in the Charleston, S.C., and inner coastal plain area 

and representative values for quartz sand fraction to 

total sand fraction .................................H145

TABLES

Table Page

1. Summary list of present age assignments and present 

known geographic distribution of selected rock units 

mapped in the Nashoba block of eastern Massachusetts 

and the Putnam block of eastern Connecticut..........H59

2. Summary list of present age assignments and present 

known geographic distribution of selected units mapped 

in the Mi 1ford-Dedham terrane of eastern Massachusetts 

and adjacent states ..................................H62

3. Texture and mineralogy of selected samples of the

Pleistocene deposits and type and reference sections of 

the Chandler Bridge Formation and the Ashley Member of 

the Cooper Formation, S .C. ..........................HI 15

4. Sediment characteristics of Pliocene units in the

Charleston, S.C., area..............................H141
GEOGRAPHIC INDEX TO ARTICLES

1. Hutchinson River Group and its subdivisions, Bronx and Westchester 

Counties, southeastern New York, p. H1-H10

2. Carboniferous formations, central Oregon, p. H11-H12

3. New Paleozoic formations, northern Kuskokwim Mountains, west-central 

Alaska, p. H13-H22

4. New stratigraphic unit in Wilcox Group, Alabama and Georgia, p. H23-H32

5. Hatchetigbee and Bashi Formations, eastern Gulf Coastal Plain, p. H33-H41

6. Formation names, Worcester area, Massachusetts, p. H43-H56

7. Stratigraphic names, eastern Massachusetts and adjacent states, p. H57- 

H72

8. Mauzy Formation, western Kentucky, p. H73-H86

9. Signal Granite, west-central Arizona, p. H87-H90

10. Members of formations in Hamilton Group, New York, p. H91-H93

11. Eastford and Canterbury Gneisses, eastern Connecticut, p. H95-H97

12. Upper Cretaceous nomenclature, Montana and South Dakota, p. H99-H104

13. Chandler Bridge Formation, lower Coastal Plain of South Carolina, p. 

H105-H124

14. New members of Madison Limestone, north-central Wyoming and southern 

Montana, p. H125-H130

15. Huntersville Chert and its Bobs Ridge Sandstone Member, from

southwestern Virginia into southwestern New York, p. H131-H133

16. Nealmont Limestone, from southwestern Virginia into southwestern New 

York, p. H135-H136

17. Goose Creek Limestone, Charleston, South Carolina, area, p. H137-H148
CONTRIBUTIONS TO STRATIGRAPHY

ADOPTION OF THE NAME HUTCHINSON RIVER GROUP AND ITS

SUBDIVISIONS IN BRONX AND WESTCHESTER COUNTIES,

SOUTHEASTERN NEW YORK

By Charles A. Baskerville 

INTRODUCTION

The Manhattan Prong of the New England upland, southeast of the 

Webster Avenue valley in Bronx County and the Bronx River valley in 

Westchester County, N.Y., consists of a series of low northeast-trending 

ridges and intervening valleys. The ridges generally are underlain by granite, 

gneissoid granite, and gneiss containing some interbedded amphibolite. The 

valleys are underlain by schist, gneiss, and amphibolite.

The purpose of this paper is to formally adopt the name Hutchinson 

River Group and to define the group which is composed of the rock types 

described above, and its included formations and subdivisions.

HUTCHINSON RIVER GROUP (HERE FORMALLY NAMED)

The Hutchinson River Group is here formally named for the 

Hutchinson River that traverses most of the subject terrane from Scarsdale, 

Westchester County, on the north to Eastchester Bay (fig. I; also see U.S. 

Geological Survey topographic map of the Mount Vernon and Flushing, N.Y. 

7 l/2-min quadrangles) in the east Bronx on the south. Seyfert and Leveson 

(1968, 1969) used the Hutchinson River Group on the basis of an informal 

oral communication from C. A. Baskerville (1967). Most of the rocks of the 

group are well exposed along the length of the river and (or) within a mile of 

it. The group consists of (in ascending order) the Hartland Formation with 

its members and the Harrison Gneiss. Figure I outlines the known outcrop 

area of the Hutchinson River Group.

The contact between the Hutchinson River Group and the New York 

City Group of Prucha (1956) is shown on the Geologic Map of New York (New 

York State Museum and Science Service, 1971) as a queried dashed line. This 

line is Cameron's Line (a fault) of western New England (Robinson and Hall, 

1979, fig. 2; Rodgers, 1970; Holl, 1979, fig. 3). The line, as it passes through 

the White Plains area of Westchester County on the Geologic Map of New 

York, is reasonably well defined; it fits the detailed mapping done by Hall 

(I968a, 1976) in the White Plains, N.Y.-Glenville, Conn., area. Pellegrini 

(1977) mapped the Mamaroneck, N.Y.-Conn., quadrangle, his work does not 

extend far enough west to further define Cameron's Line south of Hall's 

area. More detailed work in the Mount Vernon, N.Y., quadrangle, to the 

west of Pellegrini's area would fill in the gap between the work done by Hall 

and this author's area in the Bronx (southern part of the Mount Vernon quadrangle and the Flushing and Central Park, N.Y., sheets). Cameron's Line, 

therefore, has been extended south of White Plains on the Geologic Map of 

New York (New York State Museum and Science Service, 1971), bisecting the 

area east of the Bronx River valley, as an unchecked approximation.

In this paper, on the basis of I960 mapping by the author (unpub. 

data), Cameron's Line has been adjusted to what appears to be a closer

U.S. Geol. Survey BulI 1529-H, 1982, HI-H10 HI
Area 

74'OC'

 * 7- Approximat

River Group (Cafirm. Teeth on upper plate

----- Approximate boundary Pelham Bay

Long Ridge" c

1234 KILOMETERS 

APPROXIMATE SCALE

EXPLANATION

V., 'J

 . .V'.j Amphibolite

APPROXIMATE SCALE

FIGURE 1. -A, Relation of the study area, Manhattan Prong of New England upland, to the State of New 

York and the known outcrop area of the Hutchinson River Group in Westchester and Bronx Counties, N.Y. Square enclosing Pelham Bay Park is location of B, approximate outcrop area of the 

Pelham Bay Member of the Hartland Formation, a large mappable amphibolite. The location of quartz-sillimanite gneiss (1) and of a K-Ar-dated sample obtained by Long and Kulp (1962) (2) are 

shown on B. Location of Cameron's Line (3) is indicated on A.

n

|

n
CHARLES A. BASKERVILLE H3

alinement with the known locations of Hartland rocks to the east and 

Prucha's New York City rocks to the west. In the vicinity of the Cross Bronx 

Expressway, east of Third Avenue, where the highway cuts through Crotona 

Park, outcrops separated by about 10 m can be seen; the rocks to the west 

are Manhattan Schist, those to the east are schists of the Hartland 

Formation (see solid portion on Cameron's Line in fig. 1(3)). Cameron's Line 

is hypothesized to be a Taconian thrust surface separating the western 

Proterozoic Y (Fordham Gneiss in the New York City area) and miogeosynclinal Cambrian and Ordovician (Prucha's New York City Group) rocks from 

the eastern Cambrian and Ordovician eugeosynclinal rocks (Hartland 

Formation and Harrison Gneiss). The allochthonous eastern units are thought 

to be thrust westward over Prucha's miogeosynclinal New York City Group 

(Hall, I968b, 1979; Rodgers, 1970, 1971; Gates and Martin, 1976).

The Hartland rocks along strike to the northeast exhibit the same 

lithologies from the east Bronx northeastward to near Bridgeport Conn., 

where they contact the Straits Schist and Prospect Gneiss on their eastern 

border (Crowley, 1968; Hatch and Stanley, 1973). The Prospect is followed 

eastward by Gregory's (HI Rice and Gregory, 1906) "Orange phyllite" and 

"Milford chlorite schist" units, respectively; the latter borders the Triassic 

and Jurassic basin at New Haven, Conn. The Prospect, "Orange," and 

"Milford" units probably would be the rocks in contact on the east with the 

Hartland rocks southward beneath Long Island Sound; this Prospect- 

"Orange"-"Milford" sequence is considered to range in age from Middle 

Ordovician to Silurian or even Devonian from west to east (Rodgers and 

others, 1956, 1959). If similar units do exist east of the Hartland Formation 

in New York, they are beneath Long Island Sound and extend under Long 

Island east of the New York City line between Queens and Nassau Counties 

(fig. I).

The name Hutchinson River Group was proposed informally by the 

author while he was engaged in a reconnaissance study of the rocks in 

Westchester and Bronx Counties, N.Y., in 1965 (Baskerville, 1967). Seyfert 

and Leveson (1968) later mapped Twin Islands in Pelham Bay Park in detail. 

The author suggested that they use the name Hutchinson River Group as so 

little was known about the rocks east of Prucha's New York City Group at 

the time. The Geologic Map of New York showed these rocks as "schists and 

gneisses, undivided" (New York State Museum and Science Service, 1962). 

Subsequent publication by Seyfert (1968) and Seyfert and Leveson (1969) of 

their Twin Islands work placed the name Hutchinson River Group in the 

literature. Work by Hall (I968b) in the Glenville area of Connecticut (fig. I) 

and southeastern New York resulted in a subdivision of the Hartland stratigraphy into four informal members.

Rocks of the group have been considered to be pre-Triassic (Rodgers 

and others, 1956, 1959; Carr, 1960) and, more specifically, Cambrian and 

Ordovician (Hall, 1976). Clark and Kulp (1968) obtained a K-Ar age of 320 

m.y. ± 12 m.y. on muscovite from a muscovite-biotite schist near Port 

Chester, N.Y., in the Interstate 287-Interstate 95 interchange area. Long 

and others (1959) obtained a 375-m.y. K-Ar age on biotite from the Harrison 

Gneiss at Long Ridge, Conn. (fig. 1). Long and Kulp (1962) determined a KAr age of 380 m.y. on biotite from gneiss in the east Bronx. Long and Kulp's 

east Bronx biotite sample was assumed to be Fordham Gneiss of Prucha's 

New York City Group, but, from the map location (fig. IB), the author
H4 CONTRIBUTIONS TO STRATIGRAPHY

thinks that it probably belongs to the Hartland Formation. An earlier event, 

affecting New England upland rocks, is indicated by remnant K-Ar ages of 

460 m.y. to 480 m.y and is probably an early Taconian phase (Clark and Kulp, 

1968; Long and Kulp, 1962). The Taconic orogeny took place at the end of 

the Ordovician about 435 m.y. ago, and the Acadian orogeny extended from 

the Middle Devonian into the Mississippian (Rodgers, 1970, p. 216). These 

radiogenic dates indicate that the Hutchinson River Group was subjected to 

both the Taconian and Acadian events. Thus, the rocks composing the 

Hutchinson River Group may range in age from Early Cambrian to as young 

as Middle Ordovician.

The Hartland Formation and Harrison Gneiss have been mapped from 

southwestern Connecticut (Hall, I968a, b, 1976, Rodgers and others, 1956, 

1959) through eastern Westchester County (Hall I968a, b, 1976; Pellegrini, 

1977; Baskerville, 1967, and unpub. data, I960) to the East River. The 

thickness of the group or any of its subdivisions is impossible to determine 

accurately because of isoclinal folding, great variations in outcrop width 

along strike, questionable contact locations, and lack of continuity along 

strike. Figure 2 is a diagrammatic stratigraphic column of the Hutchinson 

River Group.

HARTLAND FORMATION AND ITS SUBDIVISIONS

The name Hartland was first used by Gregory (in Rice and Gregory, 

1906) to describe the rocks in Connecticut that he called Hartland (Hoosac) 

Schist; no type locality was indicated. The Hartland Formation contains 

three (Carr, I960; Gates, 1959; Pelligrini, 1977) or four (Gates and Martin, 

1976; Hall, 1976) units or informal members and is named for Hartland 

township, Hartford County, Conn.

The informal units of The Hartland as used by Hall (1976) and here 

adopted are (in ascending order) the amphibolite member, not everywhere 

present; the schist-gneiss-amphibolite member; the light-gray gneiss 

member; and the schist and granulite member. These rocks crop out over a 

width of 6 to 8 km. Hall (1976) calculated an average thickness of 2,650 m 

in the White Plains-Glenville area. Tight isoclinal folding in the east Bronx 

has probably repeated the stratigraphic section at least twice in the 3.5- to 

5.5-km width of outcrop. Therefore, the average thickness for the Hartland 

in the east Bronx is probably 1,750 to 2,750 m.

PELHAM BAY MEMBER (HERE NAMED)

The Pelham Bay Member consists of a complex of interbedded thick 

rnappable amphibolites (fig. IB), some of which contain large garnet 

porphyroblasts, light- and medium-gray ptygmatically folded gneisses, 

schists (all of which are very high grade metamorphic rocks, almost gneissic 

in this unit), granulite, and coarse pegmatites, some of which are quite 

rh'ck. On the west side of the lagoon, west of Hunter Island ((I) in fig. IB), 

biotite gneiss containing garnet is found interbedded with granulite and 

amphibolite and gray to white muscovite gneiss. The biotite gneiss has 

quartz-sillimanite bands containing large sillimanite crystals. On the basis 

of composition, this quartz-sillimanite biotite gneiss unit appears to 

correlate with the schist and granulite member of Hall (1976 and oral 

commun., 1980).
CHARLES A. BASKERVILLE H5

AGE

EAST BRONX SOUTHEAST

WESTCHESTER

SECTION

NEW YORK CITY GROUP OF

PRUCHA, 1956 

SECTION AFTER GRAUERT AND

HALL, 1973 

(AUTOCHTHONOUS ROCKS)

Silurian

Late 

Ordovician

Middle 

Ordovician

Early 

Ordovician

Late 

Cambrian

Middle 

Cambrian

Harrison 

Gneiss

Schist 

and

Granulite 

Member

Light-gray 

Gneiss 

Member

Schist^x Pel ham 

Gneiss- I Bay 

Amphibolite^) MemMember C. ber

Manhattan 

Schist

-Unconformity'

Inwood 

Marble

Amphibolite 

Member

Early 

Cambrian Unknown

Lowerre 

Quartzite

Yonkers Gneiss

Proterozoic Unknown Fordham 

Gneiss

FIGURE 2-Diagrammatic stratigraphic column of the Hutchinson River Group at its type 

locality near Hutchinson River in Manhattan Prong of New England upland southeast 

of Webster Avenue valley in Bronx County and east of Bronx River valley in 

Westchester County, southeastern New York. Informal members of the Hartland 

Formation adopted from Hall (1976).
H6 CONTRIBUTIONS TO STRATIGRAPHY

The entire rock suite in the Pelham Bay Park area appears to be the 

result of very high grade progressive metamorphism beyond that normally 

found in the Hartland Formation. Enough relict textures or fabrics remain 

from "typical" Hartland lower grade rocks that the author can see a relation 

to the schist and granulite in some facies and possibly to the schist-gneissamphibolite members of Hall (1976) with the rocks seen west of the 

Hutchinson River valley and north of Pelham Bay Park in eastern 

Westchester County.

Land exposures indicate that the Pelham Bay rocks may be as thick as 

1,500 m. The complex disappears to the east beneath Long Island Sound and 

may be much thicker. The Pelham Bay Member is here named for, and its 

type area is given as, Pelham Bay Park in northeast Bronx County.

Pelham Bay Park (see U.S. Geological Survey Flushing, N.Y., 7 1/2- 

min quadrangle) is chosen as the type area because it is a park and, as such, 

the outcrops will be protected from urbanization. They should remain easily 

accessible for study in the future. Part of this unit was mapped in detail on 

Twin Islands by Seyfert and Leveson (1969). The author has mapped the 

same units to the west, south (west of Eastchester Bay), and north (Hunter 

Island) of the Twin Islands, as well as into Westchester County in Glen Island 

Park (unpub. data, 1980; see U.S. Geological Survey Mount Vernon, N.Y., 

7 I/2-min quadrangle).

Pellegrini (1977) mapped similar rocks in the Mamaroneck, N.Y.- 

Conn., 7 I/2-min quadrangle farther northeast in Westchester County. 

Pellegrini (1977) included rocks in the Horseshoe Harbor area of Mamaroneck 

that are equivalent to the high-grade metamorphic rocks of the Pelham Bay 

Member in Hall's (1976) schist and granulite member of the Hartland.

The author's reconnaissance work (unpub. data, 1980) has not discovered similar rocks in southwestern Fairfield County, Conn.; they may 

very well be there, however. The exposures of this unit, then, are confined 

to the Long Island Sound coast of Westchester and Bronx Counties of New 

York. The Pelham Bay rocks may be beneath the sound off the Connecticut 

coast and probably occur at depth in eastern Queens County, Long Island. 

South of Eastchester Bay to the Throgs Neck peninsula, at the confluence of 

Long Island Sound and the East River, no rock crops out along the shore. If 

there were outcrops inland, they are now covered by buildings and streets.

In this paper, the Pelham Bay Member is considered to be pre-Silurian 

in age, probably from Late Cambrian to Early Ordovician. This age is based 

on a 380-m.y. K-Ar date obtained by Long and Kulp (1962) on biotite from a 

sample in this area of the east Bronx. Hall (1976) has suggested that the 

rocks of southwestern Connecticut are increasingly younger across strike 

from the west to the Harrison Gneiss on the east. This decrease in age 

implies a synform in the Westchester area, according to Hall (written 

commun., 1981), with the Harrison Gneiss in the core. The rocks east of the 

Harrison are increasingly older.

The map pattern (fig. IB) and field measurements (Baskerville, unpub. 

data, I960) in Pelham Bay Park indicate a synform plunging northerly. If the 

Harrision Gneiss in the core of this synform in Larchmont, Westchester 

County, were projected south up plunge to the Pelham Bay area
CHARLES A. BASKERVILLE H7

of the Bronx, it would be above present typography. If the units in these two 

locations (Larchmont and Pelham Bay) are indeed part of the same structure, 

the Pelham Bay rocks may be surface exposures of a deep-seated root part 

of the Hartland. These Pelham Bay rocks appear to have been subjected to 

more igneous activity than the more "typical" Hartland rocks, as the 

increased amount of amphibolite, pegmatite, and gneissoid rocks present 

indicates.

HARRISON GNEISS (NAME ADOPTED)

Merrill (1898) named the Harrison diorite for extensive outcrops in 

the town of Harrison, Westchester County, southeastern New York. Eckel 

(1902), Berkey (1907), and Ziegler (1911), among others, also used the name 

Harrison diorite. Rodgers and others (1956, 1959) renamed and redescribed 

the Harrison as the Harrison Gneiss; this usage is herein adopted by the U.S. 

Geological Survey. More recently, Harrison diorite was used by Long and 

Kulp (1962) and Ruhr (1969). Clark and Kulp (1968) changed the name 

somewhat by calling it Harrison granodiorite gneiss. Fisher and others (jri 

New York Museum and Science Service, 1971), used the name Harrison 

Gneiss in the compilation of the Geologic Map of New York. Hall (I968b), 

Sanders (1974), and Pellegrini (1975, 1977) most recently have used Harrison 

Gneiss in reference to the type rocks cropping out in the town of Harrison, 

Westchester County, N.Y.

Rodgers and others (1956, 1959) redescribed this unit as a dark-gray 

to greenish gneiss having an andesine, quartz, hornblende, and biotite 

composition and local augen structure. Their description fits the rock much 

better than descriptions of this unit as diorite by other workers. The term 

diorite applied to this rock unit would not be all encompassing, and the rock 

does not fit the plutonic definition of diorite. The Harrison has a 

predominant metamorphic gneiss texture (Ziegler, 1911).

Most geologists consider the Harrison Gneiss to be a single unit of 

rock that is well exposed in Harrison township, Westchester County, N.Y. 

Pellegrini (1977) proposed a second unit to the Harrison in the Mamaroneck, 

N.Y.-Conn., 7 l/2-min quadrangle. This second unit is similar to part of 

Hall's (1976) schist and granulite member of the Hartland Formation and is 

believed by the author to be part of the Hartland. Ries (1895) studied the 

petrography of the Harrison and gave locations in Westchester County where 

it can be seen.

Both the Hartland Formation and the Harrison Gneiss may be 

observed in almost continuous exposures from west (approximately from the 

Lake Street overpass, White Plains) to east (Port Chester, N.Y.) along the 

Cross Westchester Expressway (Interstate 287) and in the driveways and 

parking lots of vast adjoining industrial and office parks along the parallel 

service roads for about I I km.

REFERENCES CITED

Baskerville, C. A., 1967, Preliminary field study of the gneiss terrane of 

southeastern Westchester and Bronx Counties, New York [abs.]: 

Geological Society of America, Northeastern Section, Annual Meeting, 

1967, Boston, Mass., Program, p. 13-14.
H8 CONTRIBUTIONS TO STRATIGRAPHY

Berkey, C. P., 1907, Structural and stratigraphic features of the basal 

gneisses of the Highlands: New York State Museum Bulletin, v. 107, 

p. 361-378.

Carr, M. H., I960, The bedrock geology of the Naugatuck quadrangle: 

Connecticut Geological and Natural History Survey Quadrangle 

Report 9, 25 p.

Clark, G. S., and Kulp, J. L., 1968, Isotopic age study of metamorphism and 

intrusion in western Connecticut and southeastern New York: American 

Journal of Science, v. 266, p. 865-894.

Crowley, W. P., 1968, The bedrock geology of the Long Hill and Bridgeport 

quadrangles: Connecticut Geological and Natural History Survey 

Quadrangle Report 24, 81 p.

Eckel, E. C., 1902, The quarry industry in southeastern New York: New York 

State Museum, Report of the Director and State Geologist, 20th Annual 

Report, p. r 143-r 176.

Ruhr, T. W., 1969, Recent engineering data on the New York City Group 

formations, in Alexandrov, E. A., ed., Symposium of the New York City 

Group of formations, 40th Annual Meeting of the New York State 

Geological Association on May 3, 1968, at Queens College of 

C.U.N.Y.: Queens College Press Geological Bulletin 3, p. 1-10.

Gates, R. M., 1959, The bedrock geology of the Roxbury quadrangle, 

Connecticut: U.S. Geological Survey Geologic Quadrangle Map GQ-21.

Gates, R. M., and Martin, C. W., 1976, Pre-Devonian stratigraphy of central 

section of the western Connecticut Highlands, _m Page, L. R., ed., 

Contributions to the stratigraphy of New England: Geological Society 

of America Memoir 148, p. 301-336.

Grauert, B., and Hall, L. M., 1973, Age and origin of zircons from 

metamorphic rocks in the Manhattan Prong, White Plains area, 

southeastern New York: Carnegie Institution, Department of 

Terrestrial Magnetism Year Book 72, p. 293-297.

Hall, L. M., I968a, Bedrock geology in the vicinity of White Plains, New 

York, Trip A, in Guidebook to field excursions New York State 

Geological Association, 40th Annual Meeting, Flushing, N.Y., 1968: 

Brockport, N.Y., State University College, Department of Geology, 

p. 7-31.

___I968b, Geology in the Glenville area, southwesternmost Connecticut 

and southeastern New York, Trip D-6, in Guidebook for field trips in 

Connecticut New England Intercollegiate Geological Conference, 60th 

Annual Meeting, New Haven, Conn., 1968: Connecticut Geological and 

Natural History Survey Guidebook 2, 12 p.

.1976, Preliminary correlation of rocks in southwestern Connecticut, in 

Page, L. R., ed., Contributions to the stratigraphy of New EnglandT 

Geological Society of America Memoir 148, p. 337-349.
CHARLES A. BASKERVILLE H9

___1979 Meeting, Blacksburg, Va.: Virginia Polytechnic Institute and State 

University Memoir 2, p. 299-306.

Hatch, N. L., Jr., and Stanley, R. S., 1973, Some suggested stratigraphic 

relations in part of southwestern New England: U.S. Geological Survey 

Bulletin 1380, 83 p.

Long, L. E., Cobb, J. C., and Kulp, J. L., 1959, Isotopic ages on some igneous 

and metamorphic rocks in the vicinity of New York City, in Lowe, 

K. E., ed., Modern aspects of the geology of New York City and 

environs: New York Academy of Sciences Annals, v. 80, art. 4, 

p. 1140-1147.

Long, L. E., and Kulp, J. L., 1962, Isotopic age study of the metamorphic 

history of the Manhattan and Reading Prongs: Geological Society of 

America Bulletin, v. 73, p. 969-996.

Merrill, F. J. H., 1898, The geology of the crystalline rocks of southeastern 

New York: New York State Museum, 15th Annual Report, v. 1, p. 30.

New York State Museum and Science Service, 1962, Geologic map of New 

York, 1961: New York State Museum and Science Service Map and 

Chart Series 5, 10 sheets.

___1971, Geologic map of New York, 1970: New York State Museum and 

Science Service Map and Chart Series 15, 6 sheets.

Pellegrini, T. L., 1975, Lower Paleozoic metamorphic stratigraphy of the 

Mamaroneck area, New York: New York State Geological Association 

Guidebook, 47th Annual Meeting, p. 179-193.

___1977, Geologic map of the Mamaroneck quadrangle, New YorkConnecticut: New York State Museum and Science Service Map and 

Chart Series 29.

Prucha, J. J., 1956, Stratigraphic relationships of the metamorphic rocks in 

southeastern New York: American Journal of Science, v. 254, no. 11, 

p. 672-684.

___1959, Field relations bearing on the age of the New York City Group of 

the Manhattan Prong: New York Academy of Sciences Annals, v. 80, 

art. 4, p. 1159-1169.

Rice, W. N., and Gregory, H. E., 1906, Manual of the geology of 

Connecticut: State Geological and Natural History Survey Bulletin 6, 

p. 96-100.

Ries, Heinrich, 1895, On a granite-diorite near Harrison, Westchester 

County: New York Academy of Sciences Transactions Series 1, v. 14, 

p. 80-86.

Robinson, Peter, and Hall, L. M., 1979, Tectonic synthesis of southern New 

England, in Wones, D. R., ed., Proceedings, "The Caledonides in the 

U.S.A." I.G.C.P. Project 27 Caledonide Orogen, 1979 Meeting,
H10 CONTRIBUTIONS TO STRATIGRAPHY

Robinson, Peter, and Hall, L. M., 1979, Tectonic synthesis of southern New 

England, jrji Wones, D. R., ed., Proceedings, "The Caledonides in the 

U.S.A." I.G.C.P. Project 27-Caledonide Orogen, 1979 Meeting, 

Blacksburg, Va.: Virginia Polytechnic Institute and State University 

Memoir 2, p. 73-82.

Rodgers, John, 1970, The tectonics of the Appalachians: New York, 

Interscience, 271 p.

.1971, The Taconic orogeny: Geological Society of America Bulletin,

v. 82, p. I 141-1178.

Rodgers, John, Gates, R. M., Cameron, E. N., and Ross, R. J., Jr., 1956, A 

preliminary geological map of Connecticut: Connecticut Geological 

and Natural History Survey.

Rodgers, John, Gates, R. M., and Rosenfeld, J. L. 1959, Explanatory text for 

preliminary geological map of Connecticut, 1956: Connecticut 

Geological and Natural History Survey Bulletin 84, 36 p.

Sanders, J. E., 1974, Guidebook to field trip in Rockland County, New York: 

Petroleum Exploration Society of New York, p. 1-87.

Seyfert, C. K., and Leveson, D. J., 1968, Structure and petrology of Pelham 

Bay Park, Trip G, jri Guidebook to field excursions, New York State 

Geological Association, 40th Annual Meeting, Flushing, N.Y., 1968: 

Brockport, N.Y., State University College, Department of Geology, 

p. 175-195.

___1969, Speculations on the relation between the Hutchinson River Group 

and the New York City Group, in Alexandrov, E. A., ed., Symposium of 

the New York City Group of formations, 40th Annual Meeting of the 

New York State Geological Association on May 3, 1968, at Queens 

College of C.U.N.Y.: Queens College Press Geological Bulletin 3, 

p. 33-36.

Ziegler, Victor, 1911, The Ravenswood granodiorite: New York Academy of 

Sciences Annals, v. 20, p. I-10.
CONTRIBUTIONS TO STRATIGRAPHY H11

CARBONIFEROUS FORMATIONS IN CENTRAL OREGON

By Harold J. Buddenhagen'

U.S. Geological Survey Professional Paper I 110-CC, "The 

Mississippian and Pennsylvanian (Carboniferous) Systems in the United 

States California, Oregon, and Washington" contained a report by Ewart M. 

Baldwin (1979), which included a map credited to me showing these 

formations in central Oregon. Said map was taken from an uncolored copy 

that was on open-file in the office of the Oregon State Department of 

Geology and Mineral Industries in Portland. For some reason, the map in 

Professional Paper 11 10-CC differs substantially from my mapping. The 

geology of the area is very complex and obscure so it is understandable that 

different geologists would probably develop different interpretations of it. 

However, in this case, no new mapping was undertaken by Baldwin so it 

appears that the error resulted from misreading of my map: roads and other 

lines were read as formation boundaries, notably in section 25, T. 18 S., 

R. 24 E., where a strip of Upper Triassic Wade Butte Formation about 2,000 

feet wide extending westerly across this section is shown erroneously as the 

Pennsylvanian Spotted Ridge Formation. To remedy this situation, the map 

on the following page (fig. 3) is offered as a substitute for figure 20, which is 

credited to me, in Professional Paper 11 10-CC. For lack of space, this map 

does not show all occurrences of Carboniferous rocks present in this area, 

but it does show the principal ones.

REFERENCE CITED

Baldwin, E. M., 1979, Carboniferous formations in central Oregon, jri Saul, 

R. B., coordinator, and others, The Mississippian and Pennsylvanian 

(Carboniferous) Systems in the United States California, Oregon, and 

Washington: U.S. Geological Survey Professional Paper 1110-CC, 

p. CCI-CC49.

'Consulting geologist, retired, Grants Pass, OR 97526.

U.S. Geol. Survey Bull. 1529-H, 1982, p. HI 1-12
HI2 HAROLD J. BUDDENHAGEN

119°54'

r

0 1 KILOMETER

FIGURE 3.-Carboniferous formations in central Oregon: A correction to Baldwin (1979,

fig. 20, p. CC38).
CONTRIBUTIONS TO STRATIGRAPHY H13

NEW PALEOZOIC FORMATIONS IN THE

NORTHERN KUSKOKWIM MOUNTAINS,

WEST-CENTRAL ALASKA

By J. Thomas Dutro, Jr., and William W. Patton, Jr. 

ABSTRACT

Five new formations are proposed for the lower and middle Paleozoic 

sequence in the northern Kuskokwim Mountains, west-central Alaska. Four 

of these units, exposed in the Nixon Fork terrane, reflect dominantly 

shallow-water carbonate depositional environments. The Novi Mountain 

Formation, of Early Ordovician age, is overlain conformably by the Middle 

and Upper Ordovician Telsitna Formation. The Paradise Fork Formation, 

deeper water dark platy limestone and shale, lies disconformably above the 

Telsitna Formation and is of latest Llandoverian to Wenlockian (Silurian) 

Age. The Whirlwind Creek Formation, of Late Silurian to Late Devonian 

(Frasnian) age, lies unconformably on either the Paradise Fork or the 

Telsitna. The East Fork Hills Formation, a deep-water facies equivalent of 

the other four formations, crops out southeast of the platform sequence and 

is separated from it by a northeast-trending fault zone.

INTRODUCTION

Paleozoic rocks in the northern Kuskokwim Mountains occur in two 

different tectonic terranes that reflect widely separated depositional sites 

that subsequently have been juxtaposed by strike-slip faulting (fig. 4; Patton 

and others, 1980). The Nixon Fork terrane, composed of more than 5,500 m 

of predominantly shallow-water carbonate rocks of early and middle 

Paleozoic age, is fault-bounded on the southeast by the East Fork terrane 

composed of slightly metamorphosed, locally sheared and foliated, deepwater shaly carbonate rocks also of early and middle Paleozoic age. The 

Nixon Fork terrane is well exposed along a northeast-trending belt that 

underlies the higher parts of the northern Kuskokwim Mountains. The East 

Fork terrane is poorly exposed and is confined chiefly to low, densely 

forested hills bordering the Kuskokwim River valley. Both terranes are 

sliced by pervasive northeast-trending high-angle faults that parallel the 

nearby Nixon Fork-lditarod fault zone.

NIXON FORK TERRANE

The platform carbonate sequence of the Nixon Fork terrane is here 

divided into four new formations, ranging in age from Early Ordovician to 

Late Devonian (fig. 5). Depositional environments range from mainly 

supratidal laminated silty limestone in the Lower Ordovician through a 

complex array of shallow-water carbonate facies that include reefoid bodies 

in the Upper Ordovician and Middle Devonian. Dark platy limestones and 

shales containing mid-Silurian graptolites indicate deeper water paleoenvironments in that part of the Paleozoic column.

U.S. Geol. Survey Bull. 1529-H, 1982, p. HI3-H22
HI4 CONTRIBUTIONS TO STRATIGRAPHY

156° 155° 154° 153° 152°

64'

63'

McGrat

75 100 MILES

~l I I T 

25 50 75 100 KILOMETERS

EXPLANATION

Nixon Fork terrane Approximate location 

of type section of formation shown by 

letter: N, Novi Formation; T, Telsitna 

Formation; P, Paradise Fork Formation; 

W, Whirlwind Creek Formation

East Fork terrane Approximate location 

of type section of formation shown by 

letter: E, East Fork Hills Formation

Contact

Fault Dotted where concealed

FIGURE 4.-Areas of outcrop of Nixon Fork and East Fork terranes, northern 

Kuskokwim Mountains, west-central Alaska. From Patton and others, 1980.
J. THOMAS DUTRO, JR., AND WILLIAM W. RATION, JR. HIS

LLJ

V5

(A

Z

Z

111 

0

Z

E

_j

05

Z

^

o

Q 

OC

o

(A

111 

OC

111 W

Upper

Middle

Lower

Upper

?

Lower

Upper

^

2

2

Lower

STAGE

Frasnian

Givetian

EmsianSiegenian

Pridolian

Ludlovian

Wenlockian

7

Llandoverian

Maysvillian

BlackriveranChazyan

Whiterockian

Canadian

LITHIC UNIT

E3

^^

> ^ Whirlwind Creek 

frf ^ Formation

@ lisp

fir

^ \ Paradise §

Fork

Formation

"[gg"]^ Unconformity!?) 

JLJj Fault!?)

PPfl

B

^?j Telsitna 

fr?> Formation

iT/A

^ ^.t'

5§

^

S

/' "^A

^~T]J Novi Mountain

T^iTj^ Formation

EXPLANATION

1 'i 'i | Limestone

\t'>'i\ Dolomite

[-~-Ir] Shale

|^-~^]J Siltstone

rcD;'_ Limestone lens 

|*i*i*| Limestone with

chert nodules

\-f-\--\ Limey Siltstone 

bbcn Silty limestone

\&\Q$\ Coral biostromes 1 ' ''

|x"x.| Not exposed

FEET METERS

2000 -_ 600

1000-_ 300

.--,

FIGURE 5.-Generalized columnar section of lower and middle Paleozoic rocks, northern 

Kuskokwim Mountains, west-central Alaska.
H16 CONTRIBUTIONS TO STRATIGRAPHY

NOVI MOUNTAIN FORMATION (HERE NAMED) 

Name and distribution

The name Novi Mountain Formation is here applied to a nearly 900-mthick cyclically interbedded sequence of thin-bedded silty to micritic Lower 

Ordovician limestone and calcareous siltstone exposed in the vicinity of Novi 

Mountain. The type section is located on the east and west flanks of Novi 

Mountain, in sections 29, 30, and 32, T. 17 S., R. 28 E., Medfra (D-l) 

quadrangle.

The Novi Mountain Formation outcrops are characteristically 

variegated gray carbonate rocks alternating with yellow-weathering siltier 

members. The formation is mapped southwestward from its type section for 

about 25 km along a fault-bounded anticlinal structure (Patton and others, 

1980). In addition, it is present in a tightly folded anticline along the same 

trend, about 50 km southwest of Novi Mountain. The formation also is 

mapped in the area south of Browns Fork and east of White Mountain Creek.

Stratigraphy

The upper two-thirds of the Novi Mountain Formation is characterized by 5- to 30-m-thick carbonate cycles. Each cycle begins with 

massive limestone, usually containing flat carbonate pebbles at the base and 

locally abundant oolites. The thick-bedded limestone grades upward through 

thin irregularly bedded shaly limestone into calcareous siltstone or shale in 

the uppermost part of the cycle.

The type section of the Novi Mountain Formation, on Novi Mountain, 

is a composite of two measured sections with beds dipping generally northwest. The lower section is on the southeast spur of the mountain, measured 

from a low saddle at about 700 m elevation up to the crest of the ridge at 

1,040 m, near triangulation station Higher. The upper part of the formation 

is exposed on the west side of the mountain where a second section was 

measured downhill and downdip from the ridgetop to an elevation of 640 m 

where the stratigraphically highest outcrops occur. The two sections are 

correlated along the ridge by lateral tracing of cyclic units.

The lower 150 m is predominantly yellow-weathering calcareous siltstone and shale with much evidence of bioturbation. The interval from 

150-300 m is characterized by massive limestone beds, 3-5 m thick. At least 

a dozen cycles, as described above, occur from 300-600 m above the base of 

the formation. The upper 300 m of the Novi Mountain consists chiefly of 

thin irregularly bedded silty limestone and shale, in less clearly delineated 

cycles, with some units of dolomite, interpreted by us to be of supratidal 

origin. The Novi Mountain appears to grade upward into the Telsitna 

Formation in the high ridge southeast of the Telsitna River. No clear lower 

contact is mapped in that area, but the Novi Mountain lies directly on a 

lower Paleozoic or Precambrian calc-schist unit east of White Mountain 

Creek.

Fossils and age

The Novi Mountain contains few megafossils, but a sequence of sparse 

conodont faunas studied by J. E. Repetski (written commun., 1977-80)
J. THOMAS DUTRO, JR., AND WILLIAM W. RATION, JR. H17

indicates that the entire formation is of Early Ordovician age. Conodonts 

from the middle part of the formation, 300 to 600 m above its base, indicate 

North American Midcontinent Province Faunas C and D of the Lower 

Ordovician, according to Repetski. Included in these assemblages are 

Drepanodus parallelus Branson and Mehl s.f. (= in the form sense), 

Acontiodus iowensis Furnish s.f., Acontiodus cf. A. staufferi Furnish s.f., 

Drepanoistodus suberectus (Branson and MehT), Jyanognathus? sp., 

?Scolopodus filosus Ethington and Clark s.f., Scolopodus cf. 5. gracilis 

Ethington and Clark, Scolopodus sp., and Qneotodus cf. O_. variabilis 

Lindstrom.

Megafossils include gastropod steinkerns, poorly preserved 

indeterminate orthoconic cephalopods, and a few fragmental trilobites. E. 

L. Yocheteon (written commun., 1976) identified Sinuites sp. and Liospira sp., 

both common Ordovician genera. The trilobites include a possible 

hystricurinid and a pilekiinid, the latter limited to the Lower Ordovician, 

according to R. J. Ross, Jr. (written commun., 1978).

TELSITNA FORMATION (HERE NAMED) 

Name and distribution

The name Telsitna Formation is here applied to an approximately 

2,000 m-thick sequence of Middle and Upper Ordovician limestone and 

dolomite that conformably overlies the Novi Mountain Formation. The type 

section and type area are located on a high northeast-trending ridge situated 

along the divide between the head of the Telsitna River and Paradise Fork. 

The type section is almost completely exposed in southwest-dipping beds 

along the crest of the ridge in sections 17, 19, and 20, T. 18 S., R. 27 E., 

Medfra (D-2) quadrangle.

The Telsitna Formation is the most widely distributed Paleozoic map 

unit in the northern Kuskokwim Mountains. It extends from the type section 

southwestward to the Kuskokwim River near McGrath, essentially forming 

the northwest front of the mountains from near Novi Mountain on the north 

to Halfway Mountain on the south. Most of the prominent hills, including 

Limestone Mountain and Greens Head, consist of Telsitna Formation 

carbonate strata (Patton and others, 1980).

Stratigraphy

The lower 300 m of the Telsitna Formation is dominated by 

variegated light-gray to dark-brown dolomite beds. From 300 to 600 m, the 

sequence consists mainly of thin-bedded fine-grained medium-gray limestone 

with silty yellow-weathering interbeds. This part of the formation is highly 

fossiliferous, including silicified brachiopods and molluscs. Nonfossiliferous 

dolomite occurs in the interval between 600 and 1,000 m, limestone beds 

becoming more abundant in the upper 200 m. The upper 600 m of the 

formation is predominantly limestone that ranges from thick bedded and fine 

grained to thin bedded, silty, and micritic. Some black chert is present as 

scattered small nodules and lenses about 200 m below the top of the 

formation. The overlying Silurian deep-water strata of the Paradise Fork 

Formation appear to lie disconformably on the Telsitna Formation, but the 

contact may be faulted.
H18 CONTRIBUTIONS TO STRATIGRAPHY

Fossils and age

Conodonts have been identified from nearly the entire Telsitna 

Formation (A. G. Harris and J. E. Repetski, written commun., 1979). 

Samples from about 300 m above the base, in beds that also include the 

lowest occurence of Maclyrites, yielded conodonts of North American 

Midcontinent Province Middle Ordovician Fauna 3. Fauna 4 conodonts are 

reported from about 900 m above the base, and a Blackriveran (middle 

Caradocian) assemblage is identified from about 1,200 m above the base. 

Late Ordovician (probably Maysvillian) conodonts are present in the upper 50 

m of the Telsitna Formation.

The common Ordovician gastropod Maclurites ranges through much of 

the formation, from 300 m to at least 1,600 m above the base (E. L. 

Yochelson, written commun., 1978). The upper beds also contain a number 

of corals, stromatoporoids, and trilobites of Late Ordovician age. W. A. 

Oliver, Jr. (written commun., 1977-78) reports Catenipora sp., cf. Fletcheria 

sp., Pycnolithus? sp., Saffordophyllum sp., Tetradium sp., Labyrinthites sp., 

and Labechia spp., of possible Maysvillian Age. THlobites from the upper 

part of the formation, probably within the upper 100 m, are Bumastoides cf. 

B. miller! (Billings) and Sphaerexochus sp., of late Middle or Late Ordovician 

age (R. J. Ross, Jr., written commun., 1976). Ostracodes from about 1,300 

m above the base are Blackriveran in age, according to J. M. Berdan (written 

commun., 1980). The assemblage includes: Platybplbina (Platybolbina) sp., 

Craspedopyxion? off. C_.? tumblinqrunensis (Kraft. 1962), Eurychilina off. E_. 

strasburqensis Kraft, 1962, Leperditella? off. L.? gsymmetrica (Kraft, 1962), 

"Leperditella" off. "L." altiforma Harris, 1957, Steusloffina? sp., and 

Krausella sp.

PARADISE FORK FORMATION (HERE NAMED) 

Name and distribution

The name Paradise Fork Formation is here applied to a poorly exposed 

Silurian sequence, at least 1,000 m thick, of dark-gray thin-bedded platy 

limestone and black shale. The best exposures and type locality of the 

formation are located in low hills between upper Paradise Fork and upper 

Sulukna River drainages in sections II, 12, 14, and 23, T. 19 S., R. 26 E., 

Medfra (D-2) quadrangle.

This formation is mapped southwestward from its type area to White 

Mountain Creek, where it is terminated by a major northwest-trending 

vertical fault (Patton and others, 1980). The Paradise Fork Formation forms 

a generally southwest-trending synform that includes younger Devonian beds 

just north of Stone Mountain. Stone Mountain itself is composed mostly of 

undifferentiated Cretaceous strata and Upper Cretaceous and lower Tertiary 

monzonite bodies. No strata assignable to the Paradise Fork are recognized 

in the southern part of the carbonate outcrop belt.

Stratigraphy

The Paradise Fork Formation overlies, possibly disconformably, the 

Telsitna Formation and appears to reflect a change to a deeper water 

depositional environment. The dominant rock types in the lower half of the
J, THOMAS DUTRO, JR., AND WILLIAM W. PATTON, JR. H19

formation are dark-gray platy silty limestone and interbedded black silt 

shale containing nodular concretions at several horizons. Isolated limestone 

lenses and bodies up to 5 m thick occur in the upper part of the sequence.

The concretions, up to 12 cm in diameter, are composed of dark silty 

limestone and generally contain fossils or other foreign objects in their 

cores. Fossils include graptolites, ostracodes, gastropods, and cephalopods. 

In some instances, pebbles form the cores of the concretions, most of which 

also contain bits of bituminous material. Silty, yellow-weathering laminae, 

probably dolomitic, are common at several levels throughout the formation.

Fossils and age

The only diagnostic fossils from the lower part of the Paradise Fork 

Formation are graptolites that are identified by Claire Carter (written 

commun., 1978) as Monograptus cf. M. parapriodon Boucek and 

Paraplectograptus off. P. eiseli (Manck). Carter suggested a latest 

Llandoverian to early Wenlockian Age assignment. No beds dated as latest 

Ordovician or early Llandoverian were found between the uppermost dated 

Telsitna strata (Maysvillian) and the lowermost graptolite-bearing beds that 

are no more than 50 m above the base of the Paradise Fork. The absence of 

these beds suggests that there is a disconformity between the two 

formations, but field relations also allow for minor faulting along the 

contact. The age of the upper part of the formation is only roughly 

estimated, but ostracodes from near the top of the exposed sequence are 

identified by J. M. Berdan (written commun., 1979) as Herrmannina cf. H. 

caeca (Jones, 1891). Berdan states, "...Copeland (1976) shows Herrmannina 

consistently occurring below Leperditia in northern North America, and H_. 

caeca below L_. arctica in beds dated as Wenlockian in the south-central 

Arctic Islands." Consequently, the age of the uppermost part of the Paradise 

Fork is probably not younger than Wenlockian.

WHIRLWIND CREEK FORMATION (HERE NAMED) 

Name and distribution

The name Whirlwind Creek Formation is here applied to an Upper 

Silurian to Upper Devonian sequence of predominantly shallow-water 

carbonate rocks, 1,000-1,500 m thick. The type section is a south-dipping 

sequence exposed on the ridge between Whirlwind and Soda Creeks in section 

23, T. 24 S., R. 23 E., Medfra (B-3) quadrangle. The higher beds of the 

formation are measured in a supplemental section on the north flank of the 

syncline in sections 29 and 30, T. 23 S., R. 25 E., Medfra (B-3) quadrangle.

The main outcrop belt of the Whirlwind Creek Formation stretches 

northeastward for about 100 km from the type area to approximately 

latitude 64° N. (Patton and others, 1980). Exposures are generally poor 

northeast of Hardscrabble Creek. The southwestern limit of the belt is 

controlled by two intersecting faults north of Limestone Mountain. Two 

outlying masses of Whirlwind Creek Formation occur north of Stone 

Mountain and along a northwest-trending ridge west of White Mountain 

Creek. These two exposures are regionally significant because they show 

stratigraphic relations with adjacent formations. North of Stone Mountain, 

the Whirlwind Creek apparently lies above the Paradise Fork Formation, 

whereas it lies unconformably on the Telsitna Formation throughout most of
H20 CONTRIBUTIONS TO STRATIGRAPHY

the region. West of White Mountain Creek, the Whirlwind Creek is 

unconformably overlain by Permian through Lower Cretaceous strata.

Stratigraphy

Although not well exposed, the base of the formation in the type 

section appears to overlie the Telsitna Formation disconformably. The 

Whirlwind Creek consists of relatively thick cycles of dolomite and 

limestone that include some silty intervals and reefoid units with Favosites 

and other corals and stromatoporoids.

The lowermost cycle in the type section, about 250 m thick, starts 

with 80 m of algal laminated dolomite that grades upward into pelletoidal 

limestone and, finally, into silty limestone and siltstone between 80 and 

170 m above the base. The upper 80 m of this major cycle is thick-bedded 

reefy limestone with Favosites that grades into thin-bedded limestone in the 

uppermost 30 m. A second major cycle, much like the lowermost one, is 

about 400 m thick. A third cycle, also about 400 m thick, occurs at the top 

of the type section.

In the supplemental section, cycles do not appear to be as well 

developed, although the lower 250 m represents a major cycle that 

correlates with the highest cycle in the type section. The upper 300 m of 

the supplemental section consists of reefy coral-bearing limestone and 

dolomite, the latter containing several intervals of dolomite-breccia in the 

upper 100 m.

Fossils and age

The best age control for the lower part of the Whirlwind Creek is 

provided by ostracodes present in the upper parts of each major cycle. 

Ostracodes from two lower horizons, about 170 and 500 m above the base of 

the formation, are identified by J. M. Berdan (written commun., 1976) as 

Leperditia off. L_. arctica Salter, 1853, Sulcatiella Polenova, 1968, and 

Tubulibairdia? sp. Berdan states, "... It seems most probable that both 

collections are of Late Silurian age, but the possibility of a Devonian age 

cannot be ruled out."

Ostracodes from about 600-900 m above the base of the formation are 

probably of Siegenian (Early Devonian) Age, according to Berdan who states 

(written commun., 1979), "There does not appear to be any distinct change in 

thejcharacter of the ostracode assemblage as one goes up through [this part 

of the section. The taxa listed are close to forms described by Polenova 

from the Lower Devonian of Siberia, from localities ranging from Novaya 

Zemlya on the west to the Sette-Daban Range on the east, and south to the 

Salair Range on the southwest margin of the Kuznetz Basin. Except for 

cosmopolitan forms, there are few taxa in common with described North 

American faunas....There appear to be more Siegenian taxa than either 

Gedinnian or Emsian but, as ostracode ranges are not yet well known, both 

Gedinnian and Emsian beds could be present as well as Siegenian."

From the supplemental section, a relatively rich brachiopod 

assemblage and the coral Rhizophyllum, from about 250 m below the top, 

suggest an Emsian Age. Corals from elsewhere in the outcrop belt were
J. THOMAS DUTRO, JR., AND WILLIAM W. PATTON, JR. H21

identified by W. A. Oliver, Jr. (written commun., 1977). Alaiophyllum, a 

Middle Devonian genus, occurs in the outcrop north of Stone Mountain. 

Strata on both limbs of the syncline on upper Soda Creek contain both Middle 

Devonian and Late Devonian (Frasnian) corals. The Frasnian beds contain 

Smithiphyllum sp. These corals occur together with abundant Amphipora in 

beds that are correlated with the dominantly dolomitic unit in the upper 

100 m of the supplementary section.

EAST FORK TERRANE

EAST FORK HILLS FORMATION (HERE NAMED) 

Name and distribution

The name East Fork Hills Formation is here applied to a poorly 

exposed sequence of at least several hundred meters of Lower Ordovician to 

Middle Devonian dark-gray orange-weathering finely laminated limestone 

and dolomitic limestone. Because of the scattered outcrops, no continuous 

section is exposed, although several tens of meters can be examined at the 

designated type locality along the crest of the East Fork Hills in section 14, 

T. 27 S., R. 25 E., Medfra (A-3) quadrangle.

The East Fork Hills Formation is mapped along both sides of the 

North Fork of the Kuskokwim River, from just east of Limestone Mountain 

to Hardscrabble Creek and southeastward to Moose Hill (Patton and others, 

I960). None of the outcrops is particularly well exposed, and relations with 

other mapped units are obscure. Everywhere along the northwest edge of 

the outcrop belt, the East Fork Hills Formation is in fault contact with the 

Whirlwind Creek and Telsitna Formations of the Nixon Fork terrane. 

Paleozoic chert and phyllite in Grayling Hill, east of the East Fork Hills, 

may be a deeper water facies equivalent, as they are correlated with similar 

rocks near Lake Minchumina that have yielded probable Ordovician 

graptolites and radiolaria.

Stratigraphy

Outcrops of the East Fork Hills Formation are characterized by 

alternating thin bands of limestone and orange-weathering dolomite, locally 

sheared and foliated. Small-scale crossbedding and penecontemporaneous 

slump structures are common. Exposures on upper Soda Creek and Beaver 

Creek contain subordinate amounts of laminated dolomite, dark chert, and 

siliceous siltstone. Most of the outcrops are shattered by small-scale 

shearing and faulting, resulting in rubbly colluvial slopes. This formation is 

interpreted as a deep-water facies, approximately equivalent to the entire 

shallow-water carbonate sequence of the Nixon Fork terrane represented by 

the Novi Mountain, Telsitna, Paradise Fork, and Whirlwind Creek 

Formations.

Fossils and age

Conodonts are reported from several localities in the East Fork Hills 

Formation (J. E. Repetski, written commun., 1977-79), and ages range from 

Early Ordovician to Middle Devonian. This nearly complete overlap with the 

age range of the platform sequence supports the interpretation of the East
H22 CONTRIBUTIONS TO STRATIGRAPHY

Fork Hills sequence as a deep-water equivalent of the Nixon Fork terrane. 

The original relative positions of the two terranes, before the period of 

lateral faulting that has juxtaposed them, are unknown.

In addition, we suggest that the East Fork Hills Formation is at least 

partly correlative with the lime mudstone and shale of the Dillinger River 

region in the western part of the Talkeetna quadrangle to the east in the 

southern Alaska Range (Reed and Nelson, 1977).

REFERENCES CITED

Copeland, M. J., 1976, Leperditicopid ostracodes as Silurian biostratigraphic 

indices: Geological Survey of Canada Paper 76-IB, p. 83-88, pi.

Patton, W. W., Jr., Moll, E. J., Dutro, J. T., Jr., Silberman, M. L., and 

Chapman, R. M., I960, Preliminary geologic map of the Medfra quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-81 I-A, 

I over-size sheet, scale 1:250,000.

Reed, B. L., and Nelson, S. W., 1977, Geologic map of the Talkeetna 

quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies 

Map MF-870-A, scale 1:250,000.
CONTRIBUTIONS TO STRATIGRAPHY H23

NEW STRATIGRAPHIC UNIT IN THE WILCOX GROUP

(UPPER PALEOCENE-LOWER EOCENE)

IN ALABAMA AND GEORGIA

By Thomas G. Gibson

This report defines and names a new lithostratigraphic unit in the 

Wilcox Group on the basis of exposures in the coastal plains of eastern 

Alabama and western Georgia. The Baker Hill Formation of late Paleocene 

age is proposed for largely kaolinitic clay and crossbedded sand strata 

previously included in the time-equivalent, but lithologically distinct, 

Nanafalia Formation.

Mapping of Paleocene through middle Eocene strata in eastern 

Alabama and western Georgia has shown that the proposed unit is widespread 

in areas updip from those that contain the "classical" exposures of largely 

shelly glauconitic sand that are retained in the Nanafalia Formation. The 

Baker Hill Formation is well exposed in the Chattahoochee River valley 

drainage system in westernmost Georgia and easternmost Alabama, but also 

occurs over a wide area in the eastern Gulf Coastal Plain.

BAKER HILL FORMATION (HERE NAMED) 

Stratigraphy

This new formation includes the kaolinitic and bauxitic massively 

bedded clay, carbonaceous clay, and crossbedded micaceous sand found in 

the vicinity of Baker Hill, Ala. (fig. 6-A), in the Eufaula bauxite district; the 

formation extends a considerable distance westward into Alabama and 

eastward into Georgia. These strata typically have been placed in the 

Nanafalia Formation by previous authors (Warren and Clark, 1965; Clarke, 

1972). Although the strata herein placed in the Baker Hill Formation can be 

shown to be time equivalent to the shelly glauconitic sand of the Nanafalia 

(Edwards, I960; Gibson, I960), they are easily separable lithologically. The 

Baker Hill Formation occurs to the north and thus updip from exposures of 

the typical Nanafalia Formation. The Baker Hill represents deposition in 

fluvial and estuarine environments during the coastal onlap cycle in which 

the Nanafalia was deposited in inner neritic environments to the south.

The type locality of the Baker Hill Formation is herein designated as 

the Lynn Griffin //I mine in Henry County, southeastern Alabama (fig. 6-A), 

6 miles southwest of Baker Hill. The exposure on the south wall of the mine 

exhibits most of the common facies of the formation (fig. 7). The upper 

contact of the formation is exposed here, but the lower contact is below 

water level in the mine. This mine probably will continue to be a good 

exposure, but numerous other abandoned mines in the Baker Hill area also 

are available as reference sections. In addition, three other reference 

sections in Barbour and Henry Counties, Ala., are designated; these show 

various lithologies of the upper and lower portions of the formation and the 

contacts. Although kaolinitic clay is the most conspicuous lithology in the 

area, probably because of exposures in the mines, a significant thickness of 

the formation is composed of crossbedded quartz sand. The sand is fine- to

U.S. Geol. Survey Bull. 1529-H, 1982, p. H23-H32
H24

85°30'

CONTRIBUTIONS TO STRATIGRAPHY

85°00' 84°30' 84°00'

32W -

31°30' -,

55 

Tuscahoma

15 20 MILES 

I___|

0 5 10 15 20 KILOMETERS g

65 124 River section ^

Tuscahoma Tuscahoma Tuscahoma 

Clayton

B

Covered

- .2 p

3: :.:.:\ .:...fl

5-

10-

15-

-" Gravel Creek 

Sand Member 20-

-10

-20

-30

. Covered '"

EXPLANATION

 3 Gravel [rjFj Carbonaceous 

33 Sand {LK) Bauxite 

^1 Clay [^1 Shells 

IP] Glauconite |'>>'/.| Crossbedding

 Columnar section ° Town

FIGURE 6. -A, Location of Baker Hill Formation, Ala. and Ga. B, Columnar sections of 

Baker Hill Formation. Sections show change in facies downdip in Baker Hill Formation 

and into Nanafalia Formation.
THOMAS G. GIBSON H25

THICKNESS 

METERS FEET

2-

-10

4-

6--20

8-

-30

10-

12-

14-

16-

20-

-40

-50

-60

10 CLAYEY SAND, dark-red, 

highly weathered; 

grades into soil profile

X9 CLAY, laminated,

light-greenish-gray

8 FINE TO MEDIUM SAND, 

massive, glauconitic; 

clay clasts to 3 cm 

dark-red, iron-stained,

\ and locally iron-oxide-

\ cemented

7 SAND, glauconitic, shell 

molds, clay clasts, 

dark-red, iron-cemented

6 SILTY CLAY, massive, 

light-greenish-gray

5 CLAYEY FINE SAND, 

massive, micaceous, 

light-greenish-gray

FINE TO COARSE SAND, 

gravel and clay clasts 

toward bottom, generally 

well sorted; fine sand 

toward top with some 

medium sands containing 

clay clasts to 2 cm; 

micaceous, white to 

yellowish-brown

CLAY, massive, 

medium-greenish-gray

CLAY, massive, kaolinitic, 

highly carbonaceous, 

lignitic in upper 0.3 m; 

locally contains small 

clay clasts, micaceous 

medium-brownish-gray 

to black

CLAY, massive, kaolinitic, 

burrowing in upper 0.4 m, 

burrows filled with 

clayey sand sparse 

mica; light-greenish-gray

Water level

FIGURE 7.-South wall of Lynn Griffin mine #1, Henry County, Ala., type locality of 

Baker Hill Formation. Top of section 444 ft (135.3 m).
H26 CONTRIBUTIONS TO STRATIGRAPHY

coarse-grained, poorly to well-sorted, and highly micaceous and commonly 

contains clay clasts. Crossbedded sand that generally composes the lower 

beds of the formation also occurs between thick clay sequences and may be 

abundant near the top of the formation. The sand is deep red in color in 

updip more weathered exposures and white to buff in more downdip less 

weathered exposures. The crossbedding includes both planar and trough 

types, commonly is large scale with sets up to 3 to 4 feet high, and 

dominantly dips southeast to southwest although complex sets with several 

directions occur. The kaolinitic clay is generally massive in appearance; in 

the Mathison mine (section 65, fig. 6-B), a zoning pattern suggestive of a soil 

profile was observed. The clay is usually light gray to light greenish-gray in 

color, although highly weathered sections are color mottled gray-green and 

red to purple. The highest alumina content is in the pisolitic beds that 

generally occur in pod- to funnel-shaped masses tens of feet in diameter; in 

mine exposures, these beds largely have been removed. Occasionally, 

carbonaceous clay beds are present. They can be as thick as 10 feet; one of 

the thickest beds is well exposed in the Lynn Griffin //I mine. In a few 

places, the organic matter becomes concentrated enough to be considered 

lignite; these lignitic beds are 6 inches to several feet in thickness. As seen 

in subsurface cores in the Baker Hill area, several intervals of carbonaceous 

clay up to 8 to 10 feet thick may occur between kaolinitic clay beds. The 

facies changes among these lithologies are complex and rapid, both 

vertically and horizontally.

The type area of the Nanafalia Formation, by which these beds were 

previously referenced, is in western Alabama. There, the Nanafalia consists 

of a micaceous crossbedded sand named the Gravel Creek Sand Member at 

the base of the formation, a major overlying unit of glauconitic fossiliferous 

sand informally called the "Ostrea thirsae beds," and less fossiliferous 

glauconitic sand and clay of the Grampian Hills Member at the top. These 

three units are recognizable eastward into the Chattahoochee River valley, 

where they occur to the south or downdip from the area exposing the 

distinctive kaolinitic, bauxitic, and carbonaceous clay and crossbedded clayclast-bearing sand of the Baker Hill Formation.

Contact relations

The lower beds of the Baker Hill Formation usually are composed of 

red fine- to medium-grained sand that is crossbedded and micaceous and that 

contains clay clasts as large as several inches in diameter. These basal beds 

rest upon buff-colored limestone of the Clayton Formation, dark-red residual 

clay left from dissolution of the limestone, or light- to medium-gray 

massively bedded clay of the Porters Creek Formation. The surface is highly 

undulatory with 5 to 8 feet of relief noticeable within a single outcrop and 

approximately 70 feet found over a distance of a mile just north of Baker 

Hill. In the more downdip areas of the Baker Hill Formation, the 

crossbedded clay-clast-bearing basal sand of the Baker Hill rests, in places, 

upon micaceous carbonaceous sand of the Gravel Creek Sand Member of the 

Nanafalia Formation, which is sometimes found in sinkholes developed in the 

upper part of the Clayton Formation.

Throughout the Eufaula bauxite district and for a considerable 

distance west and east, the Baker Hill Formation is overlain by the 

Tuscahoma Formation. The considerably greater coastal onlap of the
THOMAS G. GIBSON H27

Tuscahoma, which has an extensive marine transgress!ve deposit at the base 

(Gibson, I960), gives a strongly planar surface to the top of the Baker Hill 

because of marine erosion. The basal beds of the Tuscahoma consist of 

shelly glauconitic sand containing abundant clay clasts and fine-grained 

quartz and phosphate gravel. Thus, the fresh greensand of the basal 

Tuscahoma (which weathers a deep red) contrasts sharply with the light-gray 

clay or buff sand of the uppermost part of the Baker Hill.

Geographic extent and thickness

The Baker Hill Formation is widespread throughout eastern Alabama 

and western and west-central Georgia. It has been recognized southwestward to Echo, Ala., where field investigations stopped (fig. 6-A). To the 

east, the formation is well exposed in the Springvale bauxite district in 

western Georgia near Cuthbert (fig. 6-A), is exposed also between Cuthbert 

and Fort Gaines, and can be traced eastward to the Andersonville bauxite 

district at Andersonville, Ga. Between the Springvale and Andersonville 

districts, the exposed sections are dominated by crossbedded sand and 

impure clay. This known distribution gives a lateral extent of at least 90 

miles for the formation with the high probability of an even greater extent 

both eastward and westward of its presently known limits. The northwestsoutheast or updip-downdip extent also is considerable. In eastern Alabama, 

kaolinitic clay and c I ay-c last-bear ing crossbedded sand extend from Clayton 

southward to about 2 miles northwest of Fort Gaines, Ga., a distance of 30 

miles, essentially at right angles to the strike of the beds in this area 

(fig. 6-A). The northern limit at Clayton occurs at elevations around 600 

feet; the Baker Hill is absent to the north because of the erosion surface 

that has cut down to Cretaceous rocks.

The formation has an average thickness of 80 to 100 feet and a 

probable range of 50 to 150 feet.

Age

The age of the Baker Hill Formation in terms of intercontinental 

zonations can be established by its equivalency with the Nanafalia 

Formation. The unconformities both above and below the Nanafalia 

Formation continue updip and bound the Baker Hill Formation also (Gibson, 

I960). In addition, Edwards (I960) found similar dinoflagellates of the same 

age both in marine beds of the Nanafalia and in carbonaceous clay beds of 

the Baker Hill Formation. The Nanafalia Formation in eastern Alabama is 

placed in calcareous nannoplankton zones NP7-NP9 of the late Paleocene by 

Bybell (I960); thus a similar age for the Baker Hill is indicated (fig. 8).

Toulmin (1977) considered the Gravel Creek Sand Member of the 

Nanafalia Formation, which occurs in sinkholes in the underlying Clayton 

Formation, to expand updip to include the entire thickness of what herein is 

called the Baker Hill Formation. Marsalis and Friddell (1975) suggested that 

the Gravel Creek occurred only in the sinkholes and was not present updip. 

The burrowed surface at the base of the "Ostrea thirsae beds" of the 

Nanafalia Formation where they overlie the Gravel Creek Sand Member in 

sinkholes, as at Franklin Landing near Fort Gaines, suggests that a time gap

exists between the two units. Evidence from spore-pollen and dinoflagellate 

assemblages suggests that the Gravel Creek beds along the Chattahoochee
FIGURE 8.-Age relations of units of late Paleocene and early Eocen

western Georgia. Patterned area indicates nondeposition. Epo

Vail and Mitchum (1979).
THOMAS G. GIBSON H29

River correlate with at least part of the Naheola Formation of western 

Alabama (Frederiksen, I960; L. E. Edwards, oral commun., 1981), the upper 

part of which belongs to calcareous nannofossil zone NP5 (L. M. Bybell, oral 

commun., 1981) (fig. 8). Thus, the Gravel Creek beds are considerably older 

than the Baker Hill Formation and the "Ostrea thirsae beds" of the 

Nanafalia. These relationships strongly support the idea of Marsalis and 

Friddell that the Gravel Creek is present only in the downdip sinkholes. The 

biostratigraphic information suggests that it is a remnant of an older 

depositional cycle than that represented by the "Ostrea thirsae beds", the 

Grampian Hills Member, and the Baker Hill Formation.

Environments of deposition

Environmental interpretations based on geographic distribution of the 

sedimentological characteristics and on paleontologic information suggest 

that the Baker Hill Formation was deposited in fluvial to estuarine 

environments separated by barrier bars from the shallow, inner neritic 

environments in which the Nanafalia Formation was deposited.

A freshwater origin is postulated for the more updip deposits. This 

interpretation is indicated by the occurrence of pollen and spores only, 

dinoflagellates being absent (Gibson, Edwards, and Frederiksen, 1980). 

However, the carbonaceous clay and lignite in the more downdip Griffin 

mine yielded a low diversity dinof lagellate assemblage suggestive of brackish 

rather than freshwater environments of deposition (Gibson, Edwards, and 

Frederiksen, I960). Samples from several carbonaceous clay intervals 1 mile 

north of Baker Hill, about 7 miles updip from the Griffin mine, yielded only 

pollen and spores and are considered to be of freshwater origin. The limited 

data seem to indicate that, at times, a transition from brackish to 

freshwater occurred in the area around Baker Hill. Additional evidence for 

brackish water environments in the more downdip areas of the Baker Hill 

Formation is the occurrence of Ophipmorpha, a noded burrow structure 

generally attributed to a callianassid shrimp, this burrow is considered by 

most workers to indicate brackish to marine waters, probably of at least 15 

to 20 parts per 1,000 salinity or greater (R. W. Frey, oral commun., 1981). 

These burrows are found only in the downdip parts of the formation, 

generally within 5 miles of the bar sands, such as those found at corehole 124 

(fig. 6-A). Here, in the most downdip part of the Baker Hill Formation, the 

section is composed almost entirely of sand, commonly gravelly and 

crossbedded and containing some clay clasts (figs. 6-B, 9). This area is 

interpreted as the barrier bar complex that allowed ponding of clay in 

estuarine and fluvial environments located to the north. Within 2 miles 

downdip (southeastward) from this corehole, equivalent strata are the shelly, 

glauconitic sand of the Nanafalia Formation as seen at Franklin Landing and 

other adjacent river sections at Fort Gaines (see River section, fig. 6-B).

Type locality

Lynn Griffin mine //I, Henry County, Ala., 5.2 miles southwest of 

Baker Hill, Ala., on west side of County Highway 29, 0.2 miles south of 

Barbour County-Henry County line, NE 1/4 sec. 4, T. 8 N., R. 27 E. 

(Lawrenceville, Alabama, 7 l/2-min quadrangle); exposes middle and upper 

parts of the formation and contact with the overlying Tuscahoma Formation.
H30 CONTRIBUTIONS TO STRATIGRAPHY

Tuscahoma Formation

Nanafalia Formation

THICK

METERS

22-

20-

1 P

16 H

14- 

12-

10-

8-

6- 

4 

2-

n

NESS

FEET

-70

-60

-50 

-40 

-30

r 20

-10

n

Not cored

 a" ' £ ' .

. ' O' .' iJ-

 . . .

Not cored

 ' * ' jj»:i

Not cored

. ' : vCC. 

.-SAX.:-. :.-.

Not cored

Not cored

 .vxx . ;

Not cored

.' -6 ' 'V*. ^'.

..v;^.:*.^.

Not cored :;:--.;-<VX.-.'

. ^ sc ^. .

Not cored

V>W N .^ .X

Not cored

VXvl y.v.v.

Not cored

Not cored

o *.'f-*'Oo-t

Not cored

*»' -<° ' i, ' 

. . a . . 

Not cored ' !' '.' '.' . 

. .xa -. : ::&'.'.

17 

16

15 

14

13 

12 

11 

10

9

8

7

6

5 

4

3

2

1

17 SAND, dark-red highly weathered (augered)

MEDIUM SAND, massive, slightly clayey, 

glauconitic, dark-red mottled yellow-orange

MEDIUM TO FINE SAND, clayey, micaceous, 

clay clasts, dark-red to red-orange

FINE TO MEDIUM SAND, massive, micaceous, thin layer 

of pebbly sand, medium-red-orange

FINE TO MEDIUM SAND, generally massive, 

some crossbeddmg, yellow-buff

MEDIUM TO COARSE SAND, massive, dark-red

FINE TO MEDIUM SAND, generally massive, some 

crossbeddmg, medium-red-orange

SAND, generally massive, some crossbeddmg, intervals of 

medium and coarse sand, well-sorted, clay clasts, 

red-orange to buff

SAND, generally massive, some crsossbeddmg, intervals of 

fine and medium sand, well-sorted and rounded, buff-gray

MEDIUM SAND, massive and crossbedded, well-sorted, 

disseminated carbonaceous debris, buff-gray

FINE SAND, mterlaminated with carbonaceous debris, dark-gray

FINE SAND, crossbedded in upper, mterlaminated with 

more clayey sand in lower, well-sorted, red-orange

SAND, massive, fine at top to medium at bottom, several 

2 cm thick bed of clayey fine sand, greenish-gray

FINE TO MEDIUM, massive, fine gravel in lowest 0.3 cm, 

red-orange to orange-brown

COARSE SAND, massive, gravel to 1 cm, medium-red-orange

MEDIUM SAND, massive, coarse grains, medium-red-orange

VERY FINE SAND, in pods and laminae with 

fine sand, clay clasts, red-orange

FIGURE 9.-Corehole section at Highland Park, Henry County, Ala. (124 on fig. 65), 

showing sand and gravel lithologies of the farthest downdip, Baker Hill Formation. 

Top of section 232 ft (70.7 m).
THOMAS G. GIBSON H3I

Reference localities

Two Mathison mines, Henry County, Ala., I mile north-northeast of 

Screamer, Ala., 200 and 400 yards north of County Highway 57, NW 1/4 

sec. 13, T. 8 N., R. 28 E. (Fort Gaines NW, Alabama, 7 l/2-min quadrangle); 

exposes middle and upper parts of the formation and contact with the 

overlying Tuscahoma Formation.

Large abandoned mine, Henry County, Ala., in SE 1/4 sec. 5, T. 8 N., 

R. 29 E., immediately east of County Highway 93 (Fort Gaines NW, 

Alabama, 7 l/2-min quadrangle); exposes middle and upper part of the 

formation and contact with the overlying Tuscahoma Formation.

Roadcut, Barbour County, Ala., on north side of County Highway 24, 

4.1 miles northwest of Baker Hill, Ala., SE 1/4 sec. 20, T. 10 N., R. 27 E. 

(Baker Hill, Alabama, 7 l/2-min quadrangle); exposes lower part of the 

formation and contact with the underlying Porters Creek Formation.

REFERENCES CITED

Bybell, L. M., I960, Paleogene calcareous nannofossils, in Frey, R. W., ed., 

Excursions in southeastern geology, v. 2 [Guidebook]: Geological 

Society of America, I960 Annual Meeting, Atlanta, Georgia: Falls 

Church, Va., American Geological Institute, p. 416-421.

Clarke, 0. M., Jr., 1972, Bauxite and kaolin in the Eufaula bauxite district, 

Alabama: Alabama Geological Survey Bulletin 100, 90 p.

Edwards, L. E., I960, Dinoflagellate biostratigraphy: A first look, in Frey, 

R. W., ed., Excursions in southeastern geology, v. 2 [Guidebook]: 

Geological Society of America, I960 Annual Meeting, Atlanta, 

Georgia: Falls Church, Va., American Geological Institute, p. 424-427.

Frederiksen, N. 0., I960, Lower Tertiary sporomorph biostratigraphy: 

Preliminary report, jri Frey, R. W., ed., Excursions in southeastern 

geology, v. 2 [Guidebook]: Geological Society of America, I960 Annual 

Meeting, Atlanta, Georgia: Falls Church, Va., American Geological 

Institute, p. 422-423.

Gibson, T. G., I960, Facies changes of lower Paleogene strata, jjn Frey, 

R. W., ed., Excursions in southeastern geology, v. 2 [Guidebook]: 

Geological Society of America, I960 Annual Meeting, Atlanta, 

Georgia: Falls Church, Va., American Geological Institute, p. 402-411.

Gibson, T. G., Edwards, L. E., and Frederiksen, N. 0., 1980, Biological 

interpretation of depositional environments in lower Paleogene strata, 

in Frey, R. W., ed., Excursions in southeastern geology, v. 2 

[Guidebook]; Geological Society of America, I960 Annual Meeting, 

Atlanta, Georgia: Falls Church, Va., American Geological Institute, 

p. 428-431.

Marsalis, W. E., and Friddell, M. S., 1975, A guide to selected Upper 

Cretaceous and lower Tertiary outcrops in the lower Chattahoochee
H32 THOMAS G. GIBSON

River valley of Georgia: Georgia Geological Society Guidebook 15, 

79 p.

Toulmin, L. D., 1977, Stratigraphic distribution of Paleocene and Eocene 

fossils in the eastern gulf coast region: Alabama Geological Survey 

Monograph 13, 602 p.

Vail, P. R., and Mitchum, R. M., Jr., 1979, Global cycles of relative changes 

of sea level from seismic stratigraphy, jn Watkins, J. S., Montadert, 

Lucien, and Dickerson, P. W., eds., Geological and geophysical 

investigations of continental margins: American Association of 

Petroleum Geologists Memoir 29, p. 472.

Warren, W. C., and Clark, L. D., 1965, Bauxite deposits of the Eufaula 

district, Alabama: U.S. Geological Survey Bulletin 1199-E, 31 p.
CONTRIBUTIONS TO STRATIGRAPHY H33

REVISION OF THE HATCHETIGBEE AND BASH1 FORMATIONS (LOWER 

EOCENE) IN THE EASTERN GULF COASTAL PLAIN

By Thomas G. Gibson 

INTRODUCTION

Mapping in eastern Alabama and western Georgia, combined with 

biostratigraphic studies in this area and in western Alabama, has led to new 

interpretations of the stratigraphic relationship of the Hatchetigbee 

Formation. The Hatchetigbee Formation usually has been subdivided into a 

basal Bashi Marl Member that is overlain by an "unnamed upper member" 

(Toulmin, 1977). As shown by Gibson and Bybell (1981), the entire "unnamed 

upper member" is an updip facies equivalent of the Bashi Marl Member, and 

both represent an equal and relatively short time interval in the early 

Eocene. Because only the "unnamed upper member" occurs in the more 

updip areas and only the Bashi Marl Member occurs over the most downdip 

with an intervening large area containing one or more tongues of each unit, 

each of these units should be treated as coeval formations. This usage 

eliminates an informal stratigraphic name (the "unnamed upper member") 

and clarifies the previous concepts that the "unnamed upper member" 

represents a considerably greater time range than the Bashi Marl Member, 

which it does not, and that its lithologies occur above the "marly" lithologies 

of the Bashi, which is not always the situation. Each formation, as revised, 

extends at least from eastern Mississippi into western Georgia.

HATCHETIGBEE FORMATION (HERE REDEFINED) 

Stratigraphy

The Hatchetigbee Formation, as redefined, includes the various 

lithologies that have been placed in its "unnamed upper member" and also 

the lithologies termed Hatchetigbee by some authors to separate mainly 

noncalcareous strata from its Bashi Marl Member. The characteristic 

lithologies of the Hatchetigbee include (I) massively bedded very fine to 

fine-grained quartz sand that is well sorted and contains little or no 

glauconite, (2) crossbedded fine- to rarely medium grained sand, and (3) 

interlaminated sequences of very fine grained sand, silt, and clay. 

Carbonaceous debris is abundant in the interlaminated sequences in western 

Alabama (Scott, 1972), but it is much less abundant in these sequences in 

eastern Alabama and western Georgia. Glauconite occurs in some beds of 

the formation but generally composes less than 2 percent. Indistinct 

lamination is present in some updip localities of the massively bedded sand, 

but the lamination is even more diffused by bioturbation in more downdip 

exposures. Scattered molluskan molds may be present, and occasionally 

silicified shells are found in thin lenticular pockets several inches in 

thickness and several to 10 feet in length. Also present is "sawdust sand," 

used in the sense of Pryor and Vanwie (1971), which is composed of silt and 

clay particles that have been flocculated and (or) rolled together into 

medium sand-sized grains. Sand units in the most updip areas in eastern 

Alabama commonly are crossbedded; the crossbeds may be undirectional and 

large scale, up to 3ft in height, or they may be smaller scale and trough

U.S. Geol. Survey Bull. 1529-H, 1982, p. H33-H4I
H34 CONTRIBUTIONS TO STRATIGRAPHY

crossbedded with several directions present. The laminae in lithology 3 may 

be parallel and continuous but commonly are discontinuous with a length of 

several inches to I to 2 ft. Clay also may occur as flaser bedding within the 

laminated sequences and as thin clay drapes on trough crossbedded strata.

The type section for the Hatchetigbee Formation is at Hatchetigbee 

Bluff on the Tombigbee River (fig. 10); here, the Hatchetigbee anticline 

brings the unit up to the surface a considerable distance downdip from most 

outcrops of the formation, and the exposure exhibits the interfingering of 

the Bashi Formation (here raised in rank) and the Hatchetigbee. Beds 2. 3, 5. 

6, 8, and 9 of this section as described by Smith, Johnson, and Langdon (1894) 

belong to the Hatchetigbee; beds 4, 7, and 10 are placed in the Bashi. 

Reference sections at Yellow Bluff and Woods Bluff (fig. 10) also are 

contained in Smith, Johnson, and Langdon (1894). Reference sections in 

eastern Alabama and western Georgia are contained herein; these consist of 

one complete section and several partial sections and include the contacts 

with the underlying and overlying formations.

Contact relations

The Hatchetigbee Formation is underlain by the Tuscahoma 

Formation or the Bashi Formation. In western Alabama and in some downdip 

exposures in eastern Alabama, sand or interlaminated silt and clay beds of 

the lowermost part of the Hatchetigbee conformably rest upon highly 

glauconitic and fossiliferous fine-grained sand of the Bashi. In updip 

exposures in eastern Alabama, fine- to medium-grained crossbedded sand 

composing the basal beds of the Hatchetigbee rests upon interlaminated silt 

and clay of the underlying Tuscahoma Formation. At localities in eastern 

Alabama and western Georgia where much of the Hatchetigbee Formation is 

composed of interlaminated sand and clay, a I-foot- to several-foot-thick 

sand bed commonly marks the base. The lower laminated beds of the 

Hatchetigbee generally are distinguished by discontinuous laminae containing 

flaser bedding, whereas the underlying Tuscahoma has planar continuous 

laminae. The contact between the Hatchetigbee and Tuscahoma Formations 

is a marine planation surface with essentially no relief.

Unconformably overlying the Hatchetigbee is either the Meridian 

Sand Member of the Tallahatta Formation or beds higher in the Tallahatta. 

In western Alabama, the Meridian Sand Member generally overlies the 

interlaminated silt and clay of the uppermost part of the Hatchetigbee; 

where the Meridian is not present, siliceous claystones of the Tallahatta rest 

upon the top of the Hatchetigbee. In eastern Alabama, a basal sand unit of 

the Tallahatta overlies the Hatchetigbee. The contact usually is a channeled 

surface with 5-20 ft of relief. The basal sand of the Tallahatta here is 

gravelly, is medium to coarse grained, is commonly crossbedded, and 

contains clay clasts as large as 3 to 4 in in diameter. The underlying 

Hatchetigbee is a massively bedded very fine grained sand showing indistinct 

lamination and moderate bioturbation fabric.

Geographic extent and thickness

The Hatchetigbee Formation has been recognized in outcrops as far 

east as Plains, Symter County, Ga. (fig. 10), where it is an interlaminated 

sequence approximately 20 ft thick. The laminated facies dominates updip
3

30°

FIGURE 10.-Locations of Hatchetigbee and Bashi sections, eastern 
H36 CONTRIBUTIONS TO STRATIGRAPHY

outcrops westward through Cuthbert, Randolph County, Ga. (fig. 10). In the 

more downdip exposures and coreholes in westernmost Georgia and eastern 

Alabama, the Hatchetigbee is mostly massively bedded sand with lesser 

amounts of discontinuously laminated sand and clay and massively bedded 

clay.

Sand with interlaminated silt and clay continues across central 

Alabama, as seen at localities along the Pea River south of Elba in Coffee 

County and at Ozark in Dale County (fig. 10). In these sections, the 

interfingering of the Hatchetigbee with the Bashi is conspicuous. The 

interfingering of the two formations is noticeable also in the more downdip 

localities in western Alabama, particularly at the type locality at 

Hatchetigbee Bluff (fig. 10). The updip localities in northern Monroe and 

Wilcox Counties are dominated by thick sequences of interlaminated sand, 

silt, and clay beds, often highly carbonaceous, of the Hatchetigbee with only 

a thin tongue of the Bashi at the base. The Hatchetigbee Formation has 

been recognized westward into Winston County, Miss. (Mellen, 1939).

In western Georgia, the Hatchetigbee Formation is from 20-30 ft 

thick updip but thins downdip to only several feet thick with the remainder 

of the sections consisting of the Bashi Formation. In the Chattahoochee 

River area, the thickness is 56 ft updip and thins downdip to I ft or less as 

shown by Gibson and Bybell (1981). This westward thickening trend 

continues across Ala. Sixty-five ft of laminated beds and sand of the 

Hatchetigbee Formation occur along the Pea River (Smith, Johnson, and 

Langdon, 1894), and the section thickens to greater than 200 ft in westcentral and western Alabama as seen in Monroe County (Scott, 1972) and 

Choctaw County (Mancini, 1981).

Age

As shown by Gibson and Bybell (1981), the "unnamed upper member" 

of the Hatchetigbee is an updip facies and time equivalent of its more 

downdip former Bashi Marl Member, herein raised in rank to Bashi 

Formation. Palynomorphs in the revised Hatchetigbee Formation establish 

its age as early Eocene (N. 0. Frederiksen, ]n. Reinhardt and Gibson, 1980, 

p. 422-423), but the absence of calcareous nannofossils and planktonic 

foraminifers does not allow a more precise placement for these beds. 

However, the time equivalency with the well-dated Bashi Formation gives 

the age of the Hatchetigbee. The age of the Bashi is in the lower part of 

calcareous nannoplankton zone NPIO and middle of planktonic foraminiferal 

zone P6 (Gibson and Bybell, 1981), placing the Hatchetigbee also in the 

earliest 500,000 years of the Eocene (fig. 11).

Environments of deposition

The Hatchetigbee Formation represents deposition in estuarine, tidal 

flat, shoreface, and very shallow inner neritic environments during the 

marine transgressive cycle in which the Bashi Formation was deposited in 

inner to middle neritic environments to the south. The sediments of the 

Hatchetigbee are interpreted as having been deposited in shallow marine and 

marginal marine environments. The massively bedded sand that dominates 

the downdip exposures in eastern Alabama and western Georgia and occurs 

less frequently in western Alabama is considered to have been deposited in
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H38 CONTRIBUTIONS TO STRATIGRAPHY

shallow inner neritic environments. The "sawdust sand" and the 

discontinuously laminated strata containing flaser bedding occur updip from 

the massively bedded sand and are interpreted as having been formed in 

shallow marine environments, ranging from very shallow neritic through 

lower shoreface to tidal flat. The highly crossbedded sand, characteristic of 

the farthest updip basal sequences, particularly in eastern Alabama, suggests 

a variety of shallow environments including offshore bars, tidal inlets, and 

possibly nearshore bars. The continuously laminated beds, which are 

commonly carbonaceous, are found throughout the geographic range of the 

Hatchetigbee but are dominant especially in western Alabama and suggest 

deposition in various tidal flat, lagoonal, and deltaic environments.

Reference sections

In addition to the type and reference sections in western Alabama 

mentioned previously, the following reference sections are included for the 

Hatchetigbee in eastern Alabama and western Georgia where it has not been 

as commonly recognized.

In Barbour County, Ala., a roadcut on north side of County Highway 

57, 100 yd east of intersection with U.S. Highway 431, sec. 29, T. 9 N., R. 28 

E. (Lawrenceville, Alabama, 7 l/2-min quadrangle); exposes lower beds of 

Hatchetigbee Formation and contact with underlying Tuscahoma Formation.

In Henry County, Ala., the west face of Mathison mine, I mi east of 

Screamer, 100 yd north of County Highway 57, NW 1/4 sec. 13, T. 8 N., R. 28 

E. (Fort Gaines NW, Alabama, 7 l/2-min quadrangle); exposes lower beds of 

Hatchetigbee Formation and contact with underlying Tuscahoma Formation.

In Randolph County, Ga., a roadcut on south side of County Highway 

152, 3.1 mi northeast of Cuthbert, 100 yd southwest of Pachitla Creek; 

exposes middle and upper parts of Hatchetigbee Formation and contact with 

overlying Tallahatta Formation.

In Dale County, Ala., a roadcut on both sides of road, 3/4 mi north of 

Bells Crossroads, NE 1/4 sec. 5, T. 6 N., R. 26 E. (Clopton, Alabamam 7 1/2- 

min quadrangle); exposes complete Hatchetigbee Formation and contacts 

with underlying Tuscahoma and overlying Tallahatta Formations.

BASHI FORMATION (HERE RAISED IN RANK) 

Stratigraphy

The Bashi Formation, here raised in rank, consists of the lithologies 

previously called the Bashi Marl Member of the Hatchetigbee Formation. 

The general sedimentary nature of the formation is of a fine- to very finegrained sand, often clayey, silty, and calcareous, massively bedded, with 

abundant glauconite (percentages commonly of 10-25 percent), and with 

abundant calcareous fossils, commonly in relatively densely packed layers. 

Rounded calcareous concretions are common. In the farthest downdip 

exposures, as along the Chattahoochee River, the formation becomes a 

clayey silt to very fine-grained sand, and shells are more disseminated 

throughout the beds.
THOMAS G. GIBSON H39

The type section for the Bashi Formation is the type of the former 

Bashi Marl Member, along the banks of Bashi Creek, northwestern Clarke 

County (fig. 10). A description of this outcrop is found in Smith, Johnson, 

and Langdon (1894). Other reference sections in western Alabama are at 

Hatchetigbee Bluff and Woods Bluff (Smith, Johnson, and Langdon, 1894), 

where the Bashi interfingers with the Hatchetigbee Formation, and at Tunnel 

Springs (Scott, 1972) where the upper part is exposed (fig. 10). Farther east 

in Alabama, good exposures are present at the dam site on the Pea River 

south of Elba (lower part of formation) and in the railroad cut north of Ozark 

where the upper part is exposed. The entire formation was exposed along 

the Chattahoochee River northwest of Blakely, Ga. (Toulmin and LaMoreaux, 

1963), although much of the section is now covered by slumps. A corehole at 

Hutchins'Landing on the Chattahoochee River northwest of Blakely is given 

in Gibson and Bybell (1981) (see locality 99, figs. 2 and 3). The farthest 

known eastward outcrop is at Greens Branch near Coleman, Ga. (fig. 10); a 

description of this exposure is given by Gibson (in_ Reinhardt and Gibson, 

1980).

Contact relations

The Bashi Formation is usually underlain by the Tuscahoma Formation 

in Alabama and westernmost Georgia. The carbonaceous interlaminated silt 

and clay beds of the Tuscahoma are easily differentiated from the 

fossiliferous glauconitic sand of the Bashi.

In western and central Alabama, the Bashi usually is overlain 

conformably by the Hatchetigbee Formation; there may be only one thin to 

thick tongue of the Hatchetigbee that overlies the Bashi or there may be an 

overlying tongue and several lower tongues that interfinger with the Bashi. 

In some places in western Alabama, the Tallahatta Formation overlies the 

Bashi, and here the basal Tallahatta deposits consist of siliceous claystone 

or, less frequently, of medium- to coarse-grained sand. In eastern Alabama, 

shelly medium-grained sand of the Tallahatta Formation overlies the clayey 

silt of the Bashi in downdip exposures. The contact is usually straight 

because of marine planation by the transgressing Tallahatta sea.

Geographic extent and thickness

The Bashi Formation has been recognized in surface outcrops from 

Coleman, Ga., on the east (fig. 10), westward across Alabama and into 

eastern Mississippi. In updip areas where the Bashi Formation is largely 

replaced by the Hatchetigbee, thicknesses of 5 to 10 ft for the Bashi are 

common. The thickness of the Bashi increases downdip and reaches 35 feet 

along the Chattahoochee River where the Bashi comprises the entire 

section. Similar thicknesses are found in Alabama in the more downdip 

localities as at Ozark, along the Pea River south of Elba, and at 

Hatchetigbee Bluff (fig. 10); at these localities, the Bashi still has some 

interfingering with the Hatchetigbee.

Age

The Bashi Formation is of earliest Eocene age, belonging to the lower 

portion of calcareous nannoplankton zone NPIO and the middle of planktonic
H40 CONTRIBUTIONS TO STRATIGRAPHY

foraminiferal zone P6 (Gibson and Bybell, 1981). This places the formation 

in the first 500,000 years of the Eocene (fig. I I).

Environments of deposition

The Bashi Formation is interpreted as having been deposited in inner 

to middle neritic environments. The more updip localities, especially those 

in which it interfingers with the Hatchetigbee Formation, contain deposits 

from inner neritic environments. The more downdip localities, best 

exemplified by the exposures and corehole along the Chattahoochee River 

northwest of Blakely, Ga., (Gibson and Bybell, 1981), probably approach 

middle neritic environments of deposition.

REFERENCES CITED

Gibson, T. G., and Bybell, L. M., 1981, Facies changes in the Hatchetigbee 

Formation in Alabama-Georgia and the Wilcox-Claiborne Group 

unconformity: Transactions of the Gulf Coast Association of 

Geological Societies, v. 31, p. 301-306.

Mancini, E. A., 1981, Lithostratigraphy and biostratigraphy of Paleocene 

subsurface strata in southwest Alabama: Transactions of the Gulf 

Coast Association of Geological Societies, v. 31, p. 359-367.

Mellen, F. F., 1939, Winston County mineral resources: Mississippi 

Geological Survey Bulletin 38, 90 p.

Pryor, W. A., and Vanwie, W. A., 1971, The "sawdust sand" An Eocene 

sediment of floccule origin: Journal of Sedimentary Petrology, v. 41, 

p. 763-769.

Reinhardt, Juergen, and Gibson, T. G., I960, Upper Cretaceous and lower 

Tertiary geology of the Chattahoochee River valley, western Georgia 

and eastern Alabama, hi Frey, R. W., ed., Excursions in southeastern 

geology, v. 2 [Guidebook]: Geological Society of America, I960 Annual 

Meeting, Atlanta, Georgia: Falls Church, Va., American Geological 

Institute, p. 385-464.

Scott, J. C., 1972, Geology of Monroe County, Alabama: Geological Survey 

of Alabama Map 101, II p.

Smith, E. A., Johnson, L. C., and Langdon, D. W., Jr., 1894, Geology of the 

coastal plain of Alabama: Alabama Geological Survey Special Report 

6, 759 p.

Toulmin, L. D., 1977, Stratigraphic distribution of Paleocene and Eocene 

fossils in the eastern gulf coast region: Alabama Geological Survey 

Monograph 13, 602 p.

Toulmin, L. D., and LaMoreaux, P. E., 1963, Stratigraphy along the 

Chattahoochee River, connecting link between Atlantic and Gulf 

Coastal Plains: American Association of Petroleum Geologists 

Bulletin, v. 47, p. 385-404.
THOMAS G. GIBSON H4I

Vail, P. R., and Mitchum, R. M., Jr., 1979, Global cycles of relative changes 

of sea level from seismic stratigraphy, _m Watkins, J. S., Montadert, 

Lucien, and Dickerson, P. W., eds., Geological and geophysical 

investigations of continental margins: American Association of 

Petroleum Geologists Memoir 29, p. 472.

CONTRIBUTIONS TO STRATIGRAPHY H43

FORMATION NAMES IN THE WORCESTER AREA, MASSACHUSETTS

By Richard Goldsmith, Edward S. Grew, J. Christopher Hepburn, 

and Gilpin R. Robinson, Jr.

ABSTRACT

The Worcester Formation of Emerson (1917) on the east flank of the 

Merrimack synclinorium, east-central Massachusetts, is redefined, and the 

fossiliferous rocks of Middle Pennsylvanian age at Worcester are here 

renamed the Coal Mine Brook Formation. Other rock units formerly 

included in Emerson's Worcester Formation and in his Brimfield Schist, 

Oakdale Quartzite, and Paxton Quartz Schist are renamed or redefined and 

reassigned new ages on the basis of recent quadrangle mapping, radiometric 

age determinations of intrusive rocks, and regional correlation. Changes 

also have been made in the nomenclature of the rocks intrusive into the 

mostly Silurian section. These rocks are the Ayer Granite, Chelmsford 

Granite, Fitchburg Complex, Newburyport Complex, and Dracut and Exeter 

Diorites.

INTRODUCTION

Recent mapping in east-central Massachusetts by geologists of the 

U.S. Geological Survey in cooperation with the Massachusetts Department of 

Public Works and by faculty and graduate students from Harvard University, 

Boston College, and the University of Massachusetts, has led to a better 

understanding of the stratigraphic and structural relations in the Worcester 

area of Massachusetts.

In addition, a number of people, principally R. H. Zartman of the U.S. 

Geological Survey and R. E. Naylor of Northeastern University, have 

recently made radiometric age determinations on intrusive and volcanic 

rocks in the area. These determinations have enabled a closer approximation 

of the age of the layered rocks. The purpose of this paper is to redefine and 

rename some of the stratigraphic units in the Worcester area and to reassign 

ages to these units on the basis of the above work. The units discussed are 

all on the east flank of the Merrimack synclinorium and lie in or west of the 

Clinton-Newbury fault zone (fig. 12).

Redefinition of many of the stratigraphic units in the Worcester area 

depends on prior redefinition of the Worcester Formation. Hence, units in 

this paper will not be discussed in order of decreasing age but will be 

discussed as names develop from the redefined Worcester. Layered rock 

units renamed and redefined fall into eastern and western sectors separated 

by the Wekepeke fault. Because correlation across this fault cannot be made 

with certainty, layered rock units in the two sectors are discussed 

separately.

U.S. Geol. Survey Bull. 1529-H, 1982, p. H43-H56
H44 CONTRIBUTIONS TO STRATIGRAPHY

43° 72°

Massabesic Gneiss Complex

and 

Permian Granite

42<

Coal Mine Brook Formation (localities 

1 and 2) and Harvard Conglomerate 

(locale 3)

/J Chelmsford Granite and Fitchburg 

Complex

i ] 111 ] I ]| Ayer Granite, Dracut and Exeter Diorites. 

and Newburyport Complex

Littleton Formation

Worchester Formation

Oakdale Formation

Paxton Formation and Merrimack Group

Tower Hill Quartzite, Boylston Schist, ~ 

Reubens Hill Formation, and Vaughn 

Hills Quartzite

Contact 

Fault

)

1 1 I 1

1 1 1 1 1 

3 10

10 20

I 

20 KILOMETERS

FIGURE 12.-Generalized geology of the east flank of the Merrimack synclinorium, 

Massachusetts and New Hampshire.
RICHARD GOLDSMITH AND OTHERS H45

LAYERED ROCKS, EASTERN SECTOR 

Worcester Formation (here redefined)

The name "Worcester" was first used by Emerson (1889, p. 560; 1898, 

p. 17) to refer to an extensive belt of argillite-, phyllite-, and chiastolitebearing mica schist in Worcester and Middlesex Counties, Mass. The 

formation was described in detail as the Worcester Phyllite by Perry and 

Emerson (1903) and Emerson (1917) and assigned a Carboniferous age on the 

basis of plant fossils found in coal-bearing beds at the Worcester "coal mine" 

(White, 1912). The Pennsylvanian age of the coal-bearing rocks has been 

recently confirmed by Grew and others (1970) and P. C. Lyons (in Grew, 

1976, p. 395). However, Grew (1970, 1973, 1976) has shown that fHe "coal 

mine" strata containing the fossils is actually separated by faults and an 

unconformity from the rest of the pelitic rocks that Emerson called 

Worcester Phyllite.

Hansen (1956), mapping in the Hudson area, changed the name to 

Worcester Formation and redefined the unit to include other rock types in 

addition to phyllite (fig. 13). The belt of Hansen's Worcester Formation in 

the Hudson quadrangle is separated by the Oakdale Formation from the main 

belt of Worcester Phyllite as mapped by Emerson (fig. 12) and lies within a 

fault zone (Skehan, 1968; Peck, 1976; Gore, 1976b).

The Worcester Formation is here redefined as the slate, phyllite, and 

metasiltstone coinciding approximately with Emerson's (1898) belt of 

Worcester Phyllite extending from the Worcester area northward into the 

towns of Clinton and Shirley, excluding the fossiliferous strata and related 

rocks of Pennsylvanian age mapped by Grew at Worcester. As so redefined, 

the Worcester no longer includes the mica schist facies, the Vaughn Hills 

Member, the phyllite facies, and the Harvard Conglomerate Lentil of Hansen 

(1956) (see fig. 13) and is geographically and stratigraphically restricted to 

exclude those units.

The Worcester Formation thus redefined is equivalent to units 3 and 4 

of Peck (1976) (see fig. 13) and the eastern belt of Crew's (1970) Holden 

Formation (unit De of Grew, 1973). Its type area would be in the Clinton 

quadrangle where the rocks were described in detail by Peck (1976). As 

redefined, the formation north of Worcester lies east of the western belt of 

the Oakdale Quartzite of Emerson (1917; Peck's unit 5) and west of the 

eastern belt of Emerson's Oakdale Quartzite, equivalent to Peck's unit 2 (not 

shown on fig. 12, south of Worcester). The Worcester Formation is offset by 

the Pine Hill fault (Grew, 1970) at Worcester and is cut off by faults to the 

north near the Massachusetts-New Hampshire border and to the south in the 

Webster area near the Massachusetts-Connecticut border. Peck (1976, p. 

244) (see fig. 13, units 3 and 4) estimated the thickness to be between 3,050 

and 4,270 m in the Clinton quadrangle. Grew (1970, p. 157) estimated the 

thickness of his "Holden Formation" to be greater than 3,000 m in the 

Worcester area.

In the Worcester area, the Worcester Formation is in an apparent 

conformable sequence with the Oakdale Quartzite of Emerson (Peck, 1976; 

Grew, 1970), which is considered to be a probable Silurian age. The 

Worcester is intruded by granite of the Fitchburg Complex, which has an
CONTRIBUTIONS TO STRATIGRAPHY

EASTERN SECTION

AGE

PENNSYLVANIAN

EARLY 

DEVONIAN 

AND 

SILURIAN

SILURIAN

SILURIAN 

OR 

ORDOVICIAN

SILURIAN (?)

ORDOVICIAN 

OR 

PROTEROZOIC Z

EMERSON (1917)

Worcester 

Phyllite

Worcester 

Phyllite

Oakdale Quartzite 

Worcester Phyllite

Oakdale 

Quartzite

Boylston Schist 

Worcester Phyllite

Brimfield 

Schist

HANSEN (1956)

Worcester 

Formation

Harvard Conglomerate Lentil of Worcester Formation

Worcester 

Formation 

(Phyllite facies)

Vaughn Hills 

Member of Worcester Formation

Wore ester Formation (mica 

schist facies )

Nashoba 

Formation

SKEHAN (1967)

Oakdale 

and 

Worcester 

Formations

Reubens Hill 

amphibolite

Vaughn Hills 

Formation

Nashoba

GREW (1970)

Worcester

Harvard 

Conglomerate

Holden Formation 

(part)

Oakdale 

Formation 

(part)

Tower Hill 

Quartzite Member 

of the 

Boylston Formation

Boylston 

Formation

PECK (1975,1976)

Units 

3 and 4

Unit 2

Unitl

Reubens Hill 

Igneous Complex

Vaughn Hills 

Member of the 

Tadmuck Brook 

Schist

Brook

Schist

THIS PAPER

Coal Mine Brook

Harvard 

Conglomerate

Worcester 

Formation

Oakdale 

Formation

Tower Hill 

Quartzite

Boylston 

Schist

Reubens Hill 

Formation

Vaughn Hills 

Quartzite

a 

| 

O

1 

5

? 

?

Tadmuck 

Brook 

Schist

Nashoba 

Formation

WESTERN SECTION

AGE

EARLY

DEVONIAN

SILURIAN

EMERSON (1917)

Brimfield Schist

Worcester Phyllite

Oakdale Quartzite 

Paxton Quartz

Schist

GREW (1970)

Holden

(part)

Oakdale

(part)

PECK (1976)

UNITS

PEASE (1972), PEPER 

AND OTHERS (1976)

South bridge

Formation

of "Paxton Group"

Bigelow Brook

Formation of

Brimfield Group

THIS PAPER

Littleton

Formation

Southbridge

Member

Bigelow Brook

Member

C Q.

 S g

£ 5

£ u

§ 1

S s

£ 5

FIGURE 13.-Layered-rock units in the east flank of the Merrimack synclinorium, 

Massachusetts and New Hampshire. Query indicates equivalent units not recognized in 

the Merrimack Group.
RICHARD GOLDSMITH AND OTHERS H47

Early Devonian age (R. E. Zartman and R. S. Naylor, written commun., 

1978). In composition and structural position, the Worcester is similar to the 

Lower Devonian Shapleigh Group of Hussey (1968) in southern Maine. Hussey 

correlated this group with the Littleton Formation of Early Devonian age in 

its type area in New Hampshire. Robinson (1981) has evidence from graded 

bedding, however, that indicates that the Worcester underlies the Oakdale. 

Because the Worcester is in a stratigraphic sequence with probable Silurian 

rocks and is intruded by the Lower Devonian Fitchburg Complex, the 

Worcester is most likely Silurian to Early Devonian in age. However, the 

stratigraphic sequence that includes the Worcester may be older than 

Silurian and Devonian if some radiometric ages obtained from the Ayer 

Granite and Newburyport Complex are correct (see below). The Worcester is 

shown on figure 13, however, in its structural and possible stratigraphic 

position above the Oakdale, rather than in a possible stratigraphic position 

beneath the Oakdale. On the basis of the evidence presented above, the 

Worcester is assigned a Silurian and probable Early Devonian age.

Coal Mine Brook Formation (here named)

The fossiliferous strata of Middle Pennsylvanian age at the Worcester 

coal mine on the property of Notre Dame Institute, Worcester (loc. 1, 

fig. 12), and garnetiferous phyllite, arkose, and conglomerate containing 

pebbles of Devonian granite near Franklin and Shrewsbury Streets, Worcester 

(loc. 2, fig. 12), described by Grew (1970, 1973, 1976) are herein named the 

Coal Mine Brook Formation after the name of the stream near the coal 

mine. According to Lyons and others (1976), the Coal Mine Brook Formation 

is correlative with the lower part of the Rhode Island Formation of Middle 

and Late Pennsylvanian age in the Narragansett basin on the basis of fossil 

flora (Westphalian C of the Canadian maritime provinces and Europe) found 

at the coal mine. Grew (1973) gives minimum thicknesses of the Coal Mine 

Brook as 330 m of conglomerate, arkose, and phyllite in downtown Worcester 

and 50 m of slate and phyllite at the coal mine, the composite type 

localities. The Coal Mine Brook Formation at the mine is less 

metamorphosed than are the adjacent regionally metamorphosed Oakdale 

and Worcester Formations.

Harvard Conglomerate (here redefined)

The nonfossiliferous Harvard Conglomerate (Crosby, 1876) considered 

by Emerson (1917) and Hansen (1956) to be a lentil in their Worcester 

Phyllite or Formation (fig. 13) is located northeast of the Coal Mine Brook 

Formation (loc. 3, fig. 12) in the same northeast-trending belt as the Coal 

Mine Brook and is involved in the same fault system (Skehan, 1968; Grew, 

1976). The Harvard also has been considered to be Pennsylvanian in age 

(Hansen, 1956; Grew, 1970, 1973, 1976; Thompson and Robinson, 1976). It 

rests unconformably on the Ayer Granite at Pin Hill, near Harvard, Mass., 

providing a lower limit for the age of the Harvard. Some uncertainty exists 

as to the age of the Ayer at this locality; the Ayer could be Silurian or Late 

Ordovician according to R. E. Zartman and R. S. Naylor (written commun., 

1978). The Harvard Conglomerate remains a valid name coequal in rank with 

the Coal Mine Brook Formation, but the age of the Harvard is considered to 

be probably Pennsylvanian.
H48 CONTRIBUTIONS TO STRATIGRAPHY

Oakdale Formation

The Oakdale Quartzite of Emerson (1917) is a calcareous 

metasiltstone and pelite that is part of a sequence described by Peck (1976), 

Grew (1970, 1973), and Robinson (1978) in the Clinton, Worcester, and 

Shirley area that also includes the Worcester Formation and orthoquartzite 

(Tower Hill Quartzite, Vaughn Hills Quartzite). This sequence is interpreted 

by Peck (1976) as a mostly distal-turbidite deposit. The Oakdale of Emerson 

is separated by the Wekepeke fault (Novotny, 1961; Peck, 1975; Pine Hill 

fault of Castle and others, 1976) into east and west belts. West of the 

Wekepeke fault, Emerson's Oakdale is equivalent to unit 5 of Peck; east of 

the Wekepeke fault, his Oakdale is equivalent to unit 2 of Peck and unit DSd 

of Grew (1973). Following Grew (1970) and Pease (1981), Emerson's Oakdale 

Quartzite is renamed the Oakdale Formation because it is not a quartzite.

The stratigraphic order of the units in the turbidite section and their 

equivalency to other units in the region have been difficult to establish 

because of faulting and thrusting. The sequence is separated from the 

Ordovician or Proterozoic Z Nashoba Formation to the east by the ClintonNewbury fault zone, but some evidence suggests that the section lies 

unconformably on the Nashoba (Alvord and others, 1976). The Oakdale is 

continuous with the Merrimack Group of southeastern New Hampshire and 

southern Maine (Hitchcock, 1877; Katz, 1917; Billings, 1956; Hussey, 1968), 

which has been correlated with fossil if erous strata of Silurian age in central 

Main (Osberg, 1968). The Oakdale is also continuous with part of the Hebron 

Formation of Connecticut (Rodgers and others, 1959). Both the Oakdale and 

the Hebron are intruded by granite dated as Silurian (R. E. Zartman and R. S. 

Naylor, written commun., 1978); and, as Dixon (1976, p. 282) has pointed out, 

the Hebron (and Oakdale) could be older than Silurian. The Oakdale 

Formation is assigned a probable Silurian age.

Tower Hill Quartzite (name adopted)

Orthoquartzite with interlayered pelite lying between the Oakdale 

Formation and the Boylston Schist (unit B of Grew, 1973) was informally 

named the Tower Hill Quartzite Member of the Boylston Formation by Grew 

(1970), and this name is formally adopted as the Tower Hill Quartzite for use 

in the Worcester area. The Tower Hill is assigned a probable Silurian age 

based on the tentative correlation of this turbidite section with the rocks in 

central Maine. G. R. Robinson, Jr., one of the authors, believes the Tower 

Hill represents a proximal facies laterally equivalent to the distal deposits 

forming the Worcester Formation.

Vaughn Hills Quartzite (here redefined)

A quartzite with associated pelite, conglomerate, and chlorite schist 

that appears to lie at the base of the turbidite section and that may or may 

not correlate with the Tower Hill Quartzite is the Vaughn Hills Member of 

the Worcester Formation of Hansen (1956). Peck (1975) considered the 

Vaughn Hills to be the upper member of the Tadmuck Brook Schist (Bell and 

Alvord, 1976), which lies on top of the Nashoba Formation east of the 

Clinton-New bury fault. The Vaughn Hills, raised to formation rank as 

Vaughn Hills Quartzite, is herein removed from the Worcester and assigned a 

probable Silurian or Ordovician age.
RICHARD GOLDSMITH AND OTHERS H49

Reubens Hill Formation (name adopted)

The Reubens Hill Formation was named by Skehan (1967), who applied 

the name to metavolcanic rocks overlying the Vaughn Hills Quartzite and 

Nashoba Formation of Ordovician or Proterozoic Z age and underlying the 

Oakdale-Worcester sequence in the Clinton-Newbury fault zone in the 

Wachusett-Marlborough tunnel. Peck (1975) changed the name to "Reubens 

Hill Igneous Complex" because it contained metadiorite. We prefer to use 

the simpler Reubens Hill Formation for this small unit. Its type area is at 

Reubens Hill east of the Wachusett Reservoir, Clinton quadrangle, Worcester 

County, Mass. In the tunnel, the Reubens Hill is 590 m thick. On the basis 

of its uncertain stratigraphic position, the Reubens Hill is assigned a Silurian 

or Ordovician age.

Boylston Schist (here restricted)

The Boylston Schist of Emerson (1917) and Grew (1970) is restricted in 

areal usage to apply to partly graphitic and pyritic pelitic, psammitic, and 

calcarenitic rocks between the Oakdale Formation and the Ordovician or 

Proterozoic Z Nashoba Formation (fig. 12). It may be equivalent in part to 

the Tadmuck Brook Schist. The Boylston is probably Silurian or Ordovician.

Merrimack Group

The Kittery Quartzite and Eliot and Berwick Formations of the 

Merrimack Group of New Hampshire and southern Maine (Katz, 1917; 

Billings, 1956; Hussey, 1968) are here recognized as valid units in 

northeastern Massachusetts. The stratigraphic order of the units is 

uncertain, but the Kittery appears to lie at the base of the group. The name 

Kittery Quartzite is changed to Kittery Formation following Novotny (1963) 

and Hussey (1968). Its age is Silurian or Ordovician because it is intruded by 

granodiorite of the Newburyport Complex dated as Silurian and Ordovican(?) 

(R. E. Zartman and R. S. Naylor, written commun., 1981). The Eliot and 

Berwick Formations remain as probable Silurian in age on the basis of 

tentative correlation with similar rocks in central Maine (Osberg, 1968).

LAYERED ROCKS, WESTERN SECTOR 

Paxton Formation

Emerson's (1917) name Paxton Quartz Schist (Paxton Schist of Perry 

and Emerson, 1903) is herewith changed to Paxton Formation because the 

unit contains a variety of rock types although it is principally a calcareous 

metasiltstone. Emerson considered the Paxton and the Oakdale to grade into 

one another, and some believe the Paxton to be a higher metamorphic grade 

equivalent to the Oakdale (see Billings, 1956). Pease (1972) and Barosh 

(1976), on the other hand, have subdivided the Paxton into the Southbridge 

Formation and an unnamed unit equivalent to part of the Hebron Formation 

of Connecticut. The Southbridge is here considered to be a member of the 

Paxton Formation. Peter Robinson, (oral commun., 1978) mapping north of 

the type area of the Brimfield Schist near Brimfield, Mass., believes that the 

Bigelow Brook Formation of the Brimfield Group (Peper and others, 1976) is 

more appropriately a member of the Paxton Formation (fig. 13) because it 

projects into Emerson's type Paxton Quartz Schist. The Paxton is continuous
H50 CONTRIBUTIONS TO STRATIGRAPHY

with part of the Merrimack Group of southeastern New Hampshire and 

probably is equivalent to the Berwick Formation of that group. The Paxton 

Formation is assigned a probable Silurian age based on the correlation with 

the Merrimack Group (Berwick part). It is intruded by granite of Silurian age 

(R. E. Zartman and R. S. Naylor, written commun., 1978), however, and 

could be older than Silurian.

INTRUSIVE ROCKS 

Ayer Granite

The Ayer Granite (Emerson, 1917), called the "Ayer crystalline 

complex" by Gore (I976a), has been divided by Gore into two facies: a 

gneissic, partly porphyritic biotite quartz monzonite (granite) to quartz 

diorite the Devens-Long Pond facies and a porphyritic biotite quartz 

monzonite (granite) the Clinton facies. Earlier U-Pb isotopic age 

determinations had shown that the Devens-Long Pond facies could not be 

dated reliably (419 m.y.-462 m.y.) (R. E. Zartman and R. S. Naylor, written 

commun., 1978). Radiometric age determinations of the Clinton facies 

indicated an Early Silurian age (about 436 m.y.). These ages were used in 

compiling a new bedrock geologic map of Massachusetts (Zen and others, 

1981). Re-evaluation of their earlier data and application of a new time 

scale has indicated a Late Ordovician or possibly an Early Silurian age 

(433 m.y. +_ 5 m.y.) for both facies (R. E. Zartman, written commun., 1981).

Chelmsford Granite

Gore (I976b) added a hydrous two-mica granite, the commercial 

"Chelmsford" of Currier (1937) and Currier and Johns (1952) and the 

Chelmsford Granite of Lyons and Faul (1968), to his "Ayer crystalline 

complex." The Chelmsford is Early Devonian in age (about 383 m.y.) (R. E. 

Zartman and R. S. Naylor, written commun., 1978) and cuts the Devens-Long 

Pond facies of the Ayer. Although the Chelmsford and the Clinton facies of 

the Ayer might be related genetically as Gore suggests, we believe the 

Chelmsford should be a unit in its own right because of the age designation 

and composition, and it has thus been so adopted by Robinson (1978).

Fitchburg Complex (here redefined)

The Fitchburg Granite (Emerson, 1917), mostly two-mica granite with 

subordinate granodiorite, has been subdivided by various workers into 

subunits including gneissic and nongneissic phases (Peper and Wilson, 1978; 

J. C. Hepburn, unpub. data, 1976) and as mapped may contain rocks of 

several ages (see Aleinikoff and others, I960). The name is changed, 

therefore, to Fitchburg Complex. U-Pb and Rb-Sr radiometric 

determinations by R. E. Zartman and R. S. Naylor (about 395 m.y.-400 m.y.) 

(written commun., 1978) indicate that granite of the Fitchburg is Early 

Devonian or younger in age. Not all subunits have been dated, however.

Massabesic Gneiss Complex (here adopted)

Pink microcline gneiss, white oligoclase gneiss, and amphibolite 

formerly included in the Fitchburg Granite (now Complex) plyton (Emerson, 

1917; Billings and others, 1952) were separated out from the Fitchburg in the
RICHARD GOLDSMITH AND OTHERS H51

Manchester, N.H., area by Sriramadas (1966) and called the Massabesic 

Gneiss. The Massabesic Gneiss, as currently mapped, is a mixed assortment 

of rocks that includes rock resembling Monson Gneiss of the Bronson Hill 

anticlinorium and rock resembling parts of the Nashoba Formation of eastern 

Massachusetts. The Massabesic has not been mapped in detail, however. 

U-Pb ages on zircons from the Massabesic range from 475 m.y. to 646 m.y. 

(Besancon and others, 1977; Aleinikoff and others, I960). Its age is thus 

uncertain, and the Massabesic may contain rocks of Ordovician or 

Proterozoic Z age or both. It is herein renamed the Massabesic Gneiss 

Complex for U.S. Geological Survey usage. The Massabesic extends into the 

Townsend area, Massachusetts, north of the main mass of the Fitchburg 

Granite (fig. 12) in an area occupied also by granite of Permian age centered 

on Milford, N.H. (Aleinikoff, 1978; Aleinikoff and others, 1980).

Newburyport Complex (here redefined)

The Newburyport Quartz Diorite of Emerson (1917) is associated with 

porphyritic quartz monzonite in the Newburyport area of Massachusetts 

(Novotny, 1969). Under the International Union of Geological Sciences 

(Streckeisen, 1973) classification, the quartz diorite is a tonalite and 

granodiorite, and the porphyritic quartz monzonite is a porphyritic granite. 

These two rocks are abruptly gradational into each other (Shride, 1971) and 

are here grouped as the renamed Newburyport Complex. Earlier U-Pb 

radiometric age determinations on zircons (R. E. Zartman and R. S. Naylor, 

written commun., 1978) indicated that the tonalite and granodiorite are 

Ordovician (about 465 m.y.) in age, and the porphyritic quartz monzonite is 

Silurian (about 437 m.y.) in age. These ages were used in compiling a new 

geologic map of Massachusetts (Zen and others, 1981). Reevaluation of the 

isotopic data from the porphyritic quartz monzonite by Zartman and Naylor 

(R. E. Zartman, written commun., 1981) has indicated an Ordovician age 

(455 m.y. _+ 15 m.y.) for it. The Newburyport Complex is believed to intrude 

the Kittery Formation of the Merrimack Group. The age of the Kittery is 

unknown but could be either Silurian or Ordovician or both. The possibility 

exists, then, that some of the Newburyport is Silurian in age.

Dracut and Exeter Diorites

Plutons of diorite, quartz diorite, granodiorite, and gabbro and norite 

associated with the Ayer Granite in east-central and northeastern 

Massachusetts and southeastern New Hampshire include the Dracut Diorite 

(Emerson, 1917) and Exeter Diorite (Hitchcock, 1877; Billings, 1956). All 

these rocks are assigned a Devonian and Silurian age on the basis of their 

spatial association with the Devonian Chelmsford and the probable Silurian 

Ayer Granites (see Sundeen, 1971; Robinson, 1978), but some masses could be 

older, as suggested by the uncertainty as to the ages of the tonalite and 

granodiorite of the Newburyport Complex and the Devens-Long Pond facies 

of the Ayer. Gaudette and others (1975) suggest that the Exeter is the same 

age as the older part of the "Hillsboro Plutonic Series" of southeastern New 

Hampshire and southwestern Maine, about 440 m.y., placing it in the Early 

Silurian or Late Ordovician.
H52 CONTRIBUTIONS TO STRATIGRAPHY

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the Milford (15') quadrangle, New Hampshire: Hanover, New 

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geochronology of the Massabesic Gneiss and the granite near Millford, 

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of southeastern New England; a guidebook for field trips to the Boston 

area and vicinity: Princeton, N.J., Science Press, p. 352-365.

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northeastern Massachusetts, hi Page, L. R., ed., Contributions to the 

stratigraphy of New England: Geological Society of America Memoir 

148, p. 179-216.

Besancon, J. R., Gaudette, H. E., and Naylor, R. S., 1977, Age of the 

Massabesic Gneiss, southeastern New Hampshire [abs]: Geological 

Society of America Abstracts with Programs, v. 5, p. 242.

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geology: Concord, N.H., New Hampshire State Planning and 

Development Commission, 203 p.

Billings, M. P., Rodgers, John, and Thompson, J. B., Jr. 1952, Geology of the 

Appalachian Highlands of east-central New York, southern Vermont, 

and southern New Hampshire: Field Trip no. I, hi Geological Society of 

America, Guidebook for field trips in New England: p. 1-71.

Castle, R. O., Dixon, H. R., Grew, E. S., Griscom, Andrew, and Zeitz, 

Isadore, 1976, Structural dislocations in eastern Massachusetts: U.S. 

Geological Survey Bulletin 1410, 39 p.

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Boston, Mass., Massachusetts Commission to the Centennial Exposition, 

42 p.
RICHARD GOLDSMITH AND OTHERS H53

Currier, L. W., 1937, The problem of the Chelmsford, Massachusetts, granite 

[abs.]: American Geophysical Union Transactions, 18th Annual 

Meeting, Part I, p. 260-261.

Currier, L. W., and Johns, R. H., 1952, Geology of the "Chelmsford granite" 

area [Mass.], ]r\_ Geological Field Trip no. 3, Society of America Annual 

Meeting, Nov. 10-12, 1952, Guidebook for field trips in New England: 

p. 105-117.

Dixon, H. R., 1976, Summary discussion of stratigraphy of eastern 

Massachusetts and Connecticut, in Page, L. R., ed., Contributions to 

the stratigraphy of New England": Geological Society of America 

Memoir 148, p. 277-284.

Emerson, B. K., 1889, Porphyritic and gneissoid granites in Massachusetts: 

Geological Society of America Bulletin, v. I, p. 559-561.

___1898, Geology of old Hampshire County, Massachusetts, comprising 

Franklin, Hampshire, and Hampden Counties: U.S. Geological Survey 

Monograph 29, 790 p.

___1917, The geology of Massachusetts and Rhode Island: U.S. Geological 

Survey Bulletin 597, 289 p.

Gaudette, H. E., Fairbairn, H. W., Kovach, Adam, Hussey, A. M., II, 1975, 

Preliminary Rb-Sr whole rock age determinations of granitic rocks in 

southwestern Maine: Geological Society of America Abstracts with 

Programs, v. 7, no. 1, p. 62-63.

Gore, R. Z. I976a, Ayer crystalline complex of Ayer, Harvard and Clinton, 

Massachusetts, m Lyons, P. C., and Brownlow, A. H., eds., Studies in 

New England Geology: Geological Society of America Memoir 146, p. 

103-124.

 1976b, Cataclastic and plutonic rocks within and west of the ClintonNewbury fault zone, east-central Massachusetts, in New England 

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Massachusetts, Oct. 8-10, 1976, Geology of southeastern New England; 

a guidebook for field trips to the Boston area and vicinity: Princeton, 

N.J., Science Press, p. 335-344.

Grew, E. S., 1970, Geology of the Pennsylvanian and pre-Pennsylvanian rocks 

of the Worcester area, Massachusetts: Cambridge, Mass., Harvard 

University, doctoral thesis, 263 p.

___1973, Stratigraphy of the Pennsylvanian and pre-Pennsylvanian rocks of 

the Worcester area, Massachusetts: American Journal of Science, v. 

273, p. 113-129.

 1976, Pennsylvanian rocks of east-central Massachusetts, j£ New 

England Intercollegiate Geological Conference, 68th Annual Meeting, 

Boston, Massachusetts, Oct. 8-10, 1976, Geology of southeastern New 

England; a guidebook for field trips to the Boston area and vicinity: 

Princeton, N.J., Science Press, p. 383-404.
H54 CONTRIBUTIONS TO STRATIGRAPHY

Grew, E. S., Mamay, S. H., and Barghoorn, E. S., 1970, Age of plant fossils 

from the Worcester coal mine, Worcester, Massachusetts: American 

Journal of Science, v. 268, p. 113-126.

Hansen, W. R., 1956, Geology and mineral resources of the Hudson and 

Maynard quadrangles, Massachusetts: U.S. Geological Survey Bulletin 

1038, 104 p.

Hitchcock, C. H., 1877, The geology of New Hampshire; Part 2, 

Stratigraphical geology: Concord, N. H., 684 p.

Hussey, A. M., II, 1968, Stratigraphy and structure of southwestern Maine, 

in Zen, E-an, White, W. S., Hadley, J. B., and Thompson, J. B., eds., 

STudies of Appalachian geology, northern and maritime: New York, 

Interscience Publishers, p. 291-301.

Katz, F. J., 1917, Stratigraphy in southeastern New Hampshire and 

southwestern Maine: U.S. Geological Survey Professional Paper 108, 

p. I 1-29.

Lyons, J. B., and Paul, Henry, 1968, Isotope geochronology of the northern 

Appalachians, m_ Zen, E-an, White, W. S., Hadley, J. B., and Thompson, 

J. B., eds., Studies of Appalachian geology, northern and maritime: 

New York, Interscience Publishers, p. 305-317.

Lyons, P. C., Tiffney, Bruce, and Cameron, Barry, 1976, Early Pennsylvanian 

age of the Norfolk basin, southeastern Massachusetts, based on plant 

megafossils, jri Lyons, P. C. and Brownlow, A. H., eds., Studies in New 

England geology: Geological Society of America Memoir 146, p. I SI200.

Novotny, R. F., 1961, A regional fault in east-central Massachusetts and 

southern New Hampshire: U.S. Geological Survey Professional Paper 

424-D, p. D48-D49.

___1963, Bedrock geology of the Dover-Exeter-Portsmouth region, New 

Hampshire: Ohio State University, doctoral thesis, 182 p.

 1969, Geology of the seacoast region of New Hampshire: Concord, 

N.H., Division of Economic Development Quadrangle Report, 46 p.

Osberg, P. H., 1968, Stratigraphy, structural geology, and metamorphism of 

the Waterville-Vassalboro area, Maine: Maine Geological Survey 

Bulletin 20, 64 p.

Pease, M. H., Jr., 1972, Geologic map of the Eastford quadrangle, Windham 

and Tolland Counties, Connecticut: U.S. Geological Survey Geologic 

Quadrangle Map GQ-1023.
RICHARD GOLDSMITH AND OTHERS H55

Peck, J. H., 1975, Preliminary bedrock geologic map of the Clinton 

quadrangle, Worcester County, Massachusetts: U.S. Geological Survey 

Open-File Report 75-658.

___1976, Silurian and Devonian stratigraphy in the Clinton quadrangle, 

central Massachusetts, hi Page, L. R., ed., Contributions to the 

stratigraphy of New England: Geological Society of America Memoir 

148, p. 241-252.

Peper, J. D., Pease, M. H., Jr., and Seiders, V. M., 1976, Stratigraphic and 

structural relationships of the Brimfield Group in northeast-central 

Connecticut and adjacent Massachusetts: U.S. Geological Survey 

Bulletin 1389, 31 p.

Peper, J. D., and Wilson, F. A., 1978, Reconnaissance bedrock geologic map 

of the Fitchburg quadrangle and part of the Ashby quadrangle, northcentral Massachusetts: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-959.

Perry, J. H., and Emerson, B. K., 1903, The geology of Worcester, 

Massachusetts: Worcester, Mass., Worcester Natural History Society, 

166 p.

Robinson, G. R., Jr., 1978, Bedrock geologic map of the Nashua River basin 

area: Pepperell, Shirley, Townsend, and part of the Ayer quadrangles, 

northeast-central Massachusetts: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-957.

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the preliminary geological map of Connecticut, 1956: Connecticut 

Geological and Natural History Survey Bulletin 84, 64 p.

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Massachusetts, area, Trip B-5, jr^ New England Intercollegiate 

Geological Conference, 63rd Annual Meeting, Concord, New 

Hampshire, 1971, Guidebook: p. 105-117.

Skehan, J. W., 1967, Geology of the Wachusett-Marlborough Tunnel, eastcentral Massachusetts, a preliminary report, ni Farquhar, 0. C., ed., 

Economic geology in Massachusetts Proceedings of a conference in 

January 1966: Amherst, Mass., Graduate School, University of 

Massachusetts, p. 237-244.

___1968, Fracture tectonics of southeastern New England as illustrated by 

the Wachusett-Marlborough Tunnel, east-central Massachusetts, jii Zen, 

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Appalachian geology, northern and maritime: New York, Interscience 

Publishers, p. 281-290.
H56 CONTRIBUTIONS TO STRATIGRAPHY

Sriramadas, Alura, 1966, Geology of the Manchester quadrangle, New 

Hampshire: New Hampshire Department of Resources and Economic 

Development Bulletin 2, 78 p.

Streckeisen, A. L., 1973, Plutonic rocks Classification and nomenclature 

recommended by the IUGS Subcommission on the Systematics of 

Igneous Rocks: Geotimes, v. 23, no. 10, p. 26-30.

Sundeen, D. A., 1971, The bedrock geology of the Haverhill 15' quadrangle, 

New Hampshire: New Hampshire Department of Resources and 

Economic Development Bulletin 5, 125 p.

Thompson, J. B., Jr., and Robinson, Peter, 1976, Geologic setting of the 

Harvard Conglomerate, Harvard, Massachusetts, in New England 

Intercollegiate Geological Conference, 68th Annual Meeting, Oct. 8-10, 

1976, Geology of southeastern New England, a guidebook for field trips 

to the Boston area and vicinity: Princeton, N.J., Science Press, 

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Sciences Journal, v. 2, p. 114-118.

Zen, E-an, ed., and Goldsmith, Richard, Ratcliffe, N. M., Robinson, Peter, 

and Stanley, Rolfe, compilers, 1981, Bedrock geologic map of 

Massachusetts: U.S. Geological Survey Open-File Report 81-1327, 

scale 1:250,000.
CONTRIBUTIONS TO STRATIGRAPHY H57

STRATIGRAPHIC NAMES IN EASTERN MASSACHUSETTS 

AND ADJACENT STATES

By Richard Goldsmith, David R. Wones, and 

Andrew F. Shride

ABSTRACT

Changes in name and age assignment and statement of geologic 

distribution for stratified and intrusive rock units in the Nashoba block of 

eastern Massachusetts and the Putnam block of eastern Connecticut and for 

stratified and intrusive rock units in the Milford-Dedham terrane of eastern 

Massachusetts and adjacent States are described and listed. These changes 

are necessary because of new radiometric age determinations on rocks in 

eastern Massachusetts, Rhode Island, and Connecticut and reconnaissance 

mapping in preparation for a new geologic map of Massachusetts.

INTRODUCTION

New radiometric age determinations on rocks in eastern 

Massachusetts, Rhode Island, and Connecticut and reconnaissance mapping 

for a new geologic map of Massachusetts have resulted in a need for 

reassignment of ages, revision of names, and restatement of geographic 

distribution for many rock units. Eastern Massachusetts is divided into two 

structural blocks by the Bloody Bluff and Lake Char fault zones: the narrow 

Nashoba and Putnam blocks on the west and the extensive Milford-Dedham 

terrane or "Eastern basement" (Avalonian) on the east (fig. 14).

Brief descriptions for changes in nomenclature are presented for rock 

units in each of two blocks. Only rock units for which changes in name, age, 

or geographic distribution are required are discussed. Changes are 

summarized on table I.

NASHOBA AND PUTNAM BLOCKS

The Nashoba block (Skehan, 1969) is bounded by the Bloody Bluff fault 

zone on the east and the Clinton-Newbury (Essex) fault zone on the west 

(fig. 14). Within the block, the stratified units are metamorphosed 

eugeosynclinal rocks of Proterozoic Z or early Paleozoic age, and the 

intrusive rocks are early to middle Paleozoic in age (table I). The stratified 

rocks do not correlate with rock units in either the Merrimack synclinorium 

to the west or the rocks of the Milford-Dedham terrane to the east. The 

stratified rocks are the Marlboro Formation, Shawsheen Gneiss, Fish Brook 

Gneiss, Nashoba Formation, and Tadmuck Brook Schist. Equivalent units in 

Connecticut are the Tatnic Hill and Quinebaug Formations of the Putnam 

Group. None of the stratified rocks are fossiliferous. Intrusive rocks in the 

Nashoba block are the Andover Granite and related rocks and the Sharpners 

Pond Diorite and related rocks.

U.S. Geol. Survey Bull. 1529-H, 1982, p. H57-H72
H58 CONTRIBUTIONS TO STRATIGRAPHY

SOUTHEASTERN 

' MASSACHUSETTS 

BATHOUTH

EXPLANATION

Paleozoic plutons

Paleozoic and older sedimentaryvolcanic basins

Contact 

Fault

------ Approximate boundary of

Rhode Island batholith

FIGURE 14.-Major geologic features of eastern Massachusetts.
RICHARD GOLDSMITH AND OTHERS H59

Table I .--Summary list of present age assignments and present known geographic 

distribution of selected rock units mapped in the Nashoba block of eastern 

Massachusetts and the Putnam block of eastern Connecticut

NAME

Fish Brook Gneiss 

Marlboro Formation

Nashoba Formation 

Quinebaug Formation

Shawsheen Gneiss 

Tadmuck Brook Schist

Tatnic Hill Formation 

Yantic Member 

Fly Pond Member

Acton Granite 

Andover Granite

Assabet Quartz Diorite 

Sharpners Pond Diorite 

Straw Hollow Diorite

AGE 

Stratified rocks

Ordovician or Proterozoic Z

Ordovician, Cambrian, 

or Proterozoic Z

Ordovician or Proterozoic Z

Ordovician, Cambrian, 

or Proterozoic Z

Ordovician or Proterozoic Z

Silurian(?), Ordovician, 

or Proterozoic Z

Ordovician or Proterozoic Z

Ordovician or Proterozoic Z 

Ordovician or Proterozoic Z

Intrusive rocks

Devonian or 

Silurian and Ordovician(?)

Devonian or 

Silurian and Ordovician(?)

Silurian 

Silurian 

Silurian

DISTRIBUTION

Massachusetts 

Massachusetts

Massachusetts

Connecticut and 

Massachusetts

Massachusetts 

Massachusetts

Connecticut and 

Massachusetts

Connecticut and 

Massachusetts

Connecticut and 

Massachusetts

Massachusetts 

Massachusetts

Massachusetts 

Massachusetts 

Massachusetts
H60 CONTRIBUTIONS TO STRATIGRAPHY

Stratified rocks

Nashoba Formation, Fish Brook Gneiss, and Shawsheen Gneiss.~The

Nashoba Formation (Hansen, 1956), the Fish Brook Gneiss (Castle, I965b), 

and the Shawsheen Gneiss (Bell and Alvord, 1976) are intruded by the Silurian 

Sharpners Pond Diorite and the Devonian or Silurian and Ordovician(?) 

Andover Granite and generally have been considered to be Ordovician or 

older. Olszewski (1978) obtained a 742-m.y.+9l-m.y. age on a concordia plot 

of zircons from the Fish Brook and Shawsheen Gneisses, units considered to 

be volcanic and volcaniclastic by Bell and Alvord. This suggests the 

possibility of a Proterozoic Z age. The stratified rocks in the Nashoba block, 

with the exception of the Tadmuck Brook Schist, are assigned an Ordovician 

or Proterozoic Z age.

Marlboro Formation. The Marlboro Formation (Emerson, 1917) was 

redefined by Bell and Alvord (1976). The Marlboro is considered here to be 

Ordovician, Cambrian, or Proterozoic Z in age because it underlies the 

Nashoba Formation and Fish Brook and Shawsheen Gneisses.

Tadmuck Brook Schist. Bell and Alvord (1976) placed the Tadmuck 

Brook Schist above the Nashoba Formation. The Tadmuck Brook is truncated 

at the top by the Clinton-Newbury fault. The Tadmuck Brook was 

considered to underlie the Silurian rocks of the Merrimack synclinorium in 

and west of the fault zone. In places in the fault zone, however, the 

Tadmuck Brook is difficult to distinguish from schist and phyllite of the 

synclinorium sequence. In addition, Alvord and others (1976, p. 327) 

suggested that the Tadmuck Brook might lie unconformably on the Nashoba 

Formation because it truncates units of the Nashoba. The age of the 

Tadmuck Brook, therefore, is considered to be SMurian(?), Ordovician, or 

Proterozoic Z.

Tatnic Hill and Quinebaug Formations. The Tatnic Hill Formation, 

with its members the Yantic and the Fly Pond, and the underlying Quinebaug 

Formation form the Putnam Group (Dixon, 1964), which lies in a structural 

block south of the Nashoba block (fig. 14). The units in the Putnam block are 

considered to be equivalent to those in the Nashoba block (Barosh, 1977; 

Barosh and others, 1977; Goldsmith, 1980). Their age is also Ordovician or 

Proterozoic Z, with the Quinebaug also possibly being of Cambrian age 

(equal to the Marlboro). These formations project into Massachusetts in the 

Webster area (Barosh, 1977; H. R. Dixon, unpub. data, 1978).

Intrusive rocks

Acton Granite. The Acton Granite (Hansen, 1956) is considered to be 

the same general age as the Andover, Devonian or Silurian and Ordovician(?) 

because its texture, mineralogy, and field relations are similar to those of 

the Andover (Castle, I965a, p. 79).

Andover Granite. The Andover Granite (Clapp, 1910) is a mass of 

syntectonic to late-tectonic granite that consists of several phases that have 

not been mapped separately. Rb-Sr age determinations by R. E. Zartman 

and R. S. Naylor (written commun., 1981) and by Handford (1965) indicate

that rocks of more than one age may be present. Masses of undeformed 

pegmatite and aplite give an Early Devonian or Late Silurian age. A gneissic
RICHARD GOLDSMITH AND OTHERS H61

phase gives an Early Silurian or Late Ordovician age. According to Castle 

(I965a), some of the Andover is gradational with phases of the Sharpners 

Pond Diorite; if so, a Silurian age is indicated for parts of the Andover. 

Until the different phases of the Andover are sorted out, a Devonian or 

Silurian and Ordovician(?) age is indicated for the Andover.

Sharpners Pond Diorite.~The Sharpners Pond Tonalite of Castle 

(I965a) is here renamed the Sharpners Pond Diorite because its compositional range is from quartz diorite to diorite according to the Streckeisen 

(1973) classification. R. E. Zartman and R. S. Naylor (written commun., 

1981) have obtained a concordant U-Th-Pb age of about 430 m.y.+5 m.y. on 

zircons from the Sharpners Pond, placing it in the Silurian.

Straw Hollow Diorite and Assabet Quartz Diorite. The Straw Hollow 

Diorite (Emerson, 1917) and Assabet Quartz Diorite (Hansen, 1956) are 

considered to be roughly equivalent in age to the Sharpners Pond on the basis 

of similar compositions and field relations (see Castle, I965a, p. 79).

MILFORD-DEDHAM TERRANE

Eastern Massachusetts is part of the "Eastern basement" or Avalonian 

terrane of southeastern New England (Lilly, 1966; Skehan, 1969; Rodgers, 

1970; Naylor, 1975; Osberg, 1978) (see fig. 14). This largely Proterozoic Z 

terrane (Zartman and Naylor, 1972; Kovach and others, 1977; Smith and 

Giletti, 1978) extends from near New Haven, Conn., through southeastern 

Connecticut, western Rhode Island, and into Massachusetts east of the Lake 

Char and Bloody Bluff faults. In places, basins of Paleozoic and Mesozoic 

sedimentary and volcanic rocks lie in the Proterozoic Z rocks, and on Cape 

Cod a cover of Tertiary and Quaternary sediments overlies the basement. 

The older rocks of the terrane are intruded by Paleozoic granitoid rocks, 

mostly alkalic, of several ages and by mafic dikes of Mesozoic age.

Granitoid rocks, both gneissic and nongneissic, comprise a large part 

of the terrane. The widely distributed Proterozoic Z Dedham Granite and 

the commercial Proterozoic Z Milford Granite give their names to the 

terrane. Metasedimentary and metavolcanic rocks, including mafic plutonicvolcanic complexes, form marginal belts, enclaves, and roof pendants within 

the granitoid rocks. An episode of Proterozoic Z volcanism seems to have 

occurred (Kaye and Zartman, 1980).

Changes in age designations, nomenclature, and geographic 

distribution are discussed for the units listed in table 2. Where fossils are 

lacking, radiometric age determinations are assumed to be definitive in 

determining ages.

Stratified rocks

Bellingham Conglomerate. The age of the Bellingham Conglomerate 

is changed from Pennsylvanian to Pennsylvanian, Cambrian, or Proterozoic Z 

because the formation is not fossil if erous and lithologies in part resemble 

those in the Boston basin to the north, which, according to Kaye and 

Zartman (1980), could be as old as Proterozoic Z. The rocks, in part, are 

similar also to the Lower Pennsylvanian Pondville Conglomerate at the base 

of the Pennsylvanian sequence in the Northfolk and the Narragansett basins.
Table 2. Summary list of present age assignments and present known 

mapped in the Milford-Dedham terrane of eastern Massachusetts and 

NAME

Bellingham Conglomerate

Blackstone Group (with its Mussey 

Brook Schist, Quinnville Quartzite, 

Sneech Pond Schist, and Hunting 

Hill Greenstone)

Cambridge Argillite 

(of Boston Bay Group)

Hoppin Formation 

Lynn Volcanic Complex

Mattapan Volcanic Complex 

Plainfield Formation

Roxbury Conglomerate 

(of Boston Bay Group) (with its 

Brookline, Dorchester, and 

Squantum Members)

Westboro Formation

Beverly Syenite 

(of Cape Ann Complex)

Blue Hills Granite Porphyry

Brighton Melaphyre 

(of Boston Bay Group)

AGE 

Stratified rocks

Pennsylvanian, Cambria

Proterozoic Z

Proterozoic Z

Cambrian(?) and 

Proterozoic Z

Early and Middle Cambr

Early Devonian, Silurian

Proterozoic Z

Proterozoic Z or younge

Proterozoic Z

Cambrian(?) and 

Proterozoic Z

Proterozoic Z

Intrusive rocks

Early Silurian or Late O

Early Silurian or Late O

Pennsylvanian, Cambria

or Proterozoic Z
Bulgarmarsh Granite

Cape Ann Complex

Cherry Hill Granite

Dedham Granite 

(includes Barefoot Hills Quartz 

Monzonite of Lyons, 1969, and 

Lyons and Wolf e, 1 97 1 )

Esmond Granite 

Grant Mills Granodiorite

Hope Valley Alaskite Gneiss 

(of Sterling Plutonic Group)

Milford Granite

Peabody Granite

Ponaganset Gneiss 

(of Sterling Plutonic Group)

Scituate Granite Gneiss 

(of Sterling Plutonic Group)

Sharon Syenite

Squam Granite 

(of Cape Ann Complex)

Topsfield Granodiorite 

Wenham Monzonite

Proterozoic Z

Early Silurian or Late 

Devonian

Proterozoic Z

Proterozoic Z 

Proterozoic Z

Proterozoic Z 

Proterozoic Z

Middle Devonian 

Proterozoic Z

Proterozoic Z

Proterozoic Z

Early Silurian or Lat

Proterozoic Z 

Early Devonian
H64 CONTRIBUTIONS TO STRATIGRAPHY

Blockstone Group.~The Blackstone Series of Rhode Island 

(Woodworth, |n Shaler and others, 1899) was subdivided by Quinn and others 

(1948, 1949) into four formations: the Hunting Hill Greenstone, the Mussey 

Brook Schist, the Quinnville Quartzite, and the Sneech Pond Schist and 

assigned a probable Proterozoic Z age. The Blackstone is now reduced to 

group status (Goldsmith, I960), geographically extended into eastern 

Massachusetts, and assigned a definite Proterozoic Z age because units of 

the group are intruded by Proterozoic Z plutonic rocks and are more 

metamorphosed than the nearby Cambrian Hoppin Formation.

Cambridge Argil life and Roxbury Conglomerate.---The Cambridge 

Argillite; the Roxbury Conglomerate with its Brookline, Dorchester, and 

Squantum Members as defined by Billings (1976); and associated mafic and 

felsic volcanic rocks, the Brighton Melaphyre, comprise the Boston Bay 

Group. The Boston Bay Group has been considered to be Pennsylvanian in 

age on the basis of now discredited plant fossils and by correlation with 

rocks of the Narragansett basin (see Billings, 1976, and Billings, ,m Skehan 

and others, 1979). P. C. Lyons (written commun., 1981) suggests that some 

or all of the Boston Bay Group could be Devonian or Mississippian because 

the Cambridge Argillite lacks the plant fossils so abundant in the Rhode 

Island Formation of the Narragansett basin. Cameron and Jeanne (1976) 

suggest an Ordovician age for the Boston Bay Group. Recent isotopic dating 

of the Mattapan Volcanic Complex and field observations by Kaye (Kaye and 

Zartman, I960) indicate that the Boston Bay Group underlies fossiliferous 

Cambrian strata and, thus, the Boston Bay Group may be as old as 

Proterozoic Z. In support of Kaye and Zartman's thesis, acritarchs of 

Proterozoic Z to Early Cambrian age have been identified recently in the 

Cambridge Argillite (Lenk and others, 1982). Accordingly, the age of the 

Boston Bay Group could be limited to, and is most likely, Proterozoic Z and 

possibly Early Cambrian. The Boston Bay Group is shown as Paleozoic or 

Proterozoic Z on a new bedrock geologic map of Massachusetts (Zen and 

others, 1981) that was compiled before the fossil discovery.

Hoppin Formation. The name Hoppin Slate of Emerson (1917; see 

Foerste, jm Shaler and others, 1899) is changed herein to Hoppin Formation 

because the rock is not strictly a slate and contains limestone, shaley 

limestone, sandstone, and conglomeratic quartzite.

Lynn Volcanic Complex. The Lynn Volcanic Complex (LaForge, 1932) 

has been correlated with the Upper Silurian and Lower Devonian(?) Newbury 

Volcanic Complex (Shride, 1976; Billings, 1976) and with the Proterozoic Zor 

younger Mattapan Volcanic Complex (see discussions by Shride, 1976, 

p. 173-174, and Billings, jn Skehan and others, 1979, p. AI7-AI8). The Lynn 

is intruded by alkalic grariTte of the Quincy type (LaForge, 1932, p. 33), but, 

according to R. L. Zartman (oral commun.. I960), two groups of alkalic rocks 

exist in the area, one of Ordovician age (Quincy type) and one of Devonian 

age (Peabody type). We do not know which of the two intrude the Lynn at 

LaForge's locality. The Lynn could range in age from Devonian to 

Proterozoic Z and, therefore, is assigned an Early Devonian, Silurian, or 

Proterozoic Z age.
RICHARD GOLDSMITH AND OTHERS H65

Mattapan Volcanic Complex.~The Mattapan Volcanic Complex 

(LaForge, 1932) unconformably underlies the Roxbury Conglomerate of the 

Boston Bay Group, according to Billings (1976). Correlation with volcanic 

rocks of Pennsylvanian age adjacent to the Norfolk basin and in the 

Narragansett basin would permit a Pennsylvanian age. Correlation with the 

adjacent Lynn Volcanic Complex, on the other hand, would permit an age as 

young as Early Devonian. Field relations indicate the Mattapan to be 

younger than the Dedham Granite. U-Th-Pb radiometric ages on zircons 

from the Mattapan by Zartman (Kaye and Zartman, 1980) give a 

602-m.y.+3-m.y. age for the Mattapan. If the zircon age is accepted, the 

Mattapan would be Proterozoic Z or younger (earliest Cambrian?). The 

Mattapan, therefore, is assigned a Proterozoic Z or younger age.

Westboro and Plainfield Formations.--The Plainfield Formation of 

Connecticut and southern Rhode Island and the Westboro Formation of 

Massachusetts are designated Proterozoic Z because they are intruded by 

Proterozoic Z granitoid rocks of the Rhode Island batholith (Zartman and 

Naylor, 1972, and written commun., 1978; Nelson, 1975; Goldsmith, I960). 

The Plainfield and the Westboro are similar in composition and occupy a 

similar structural-stratigraphic position. They are correlated with part or 

all of the Blackstone Group. The Plainfield extends into Massachusetts in 

and along the western flank of the Rhode Island batholith.

Intrusive rocks

Barefoot Hills Quartz Monzonite.~The Barefoot Hills Quartz 

Monzonite of Lyons (1969) and Lyons and Wolfe (1971) is considered to be 

coeval with (Lyons, 1969), or a phase of (Wones, 1978), the Dedham Granite 

and, therefore, is included in the Dedham and assigned a Proterozoic Z age.

Beverly Syenite.~The Beverly Syenite is a facies of the Cape Ann 

Complex according to Dennen (1976). Its age designation, thus, is changed 

from late(?) Paleozoic to: Early Silurian or Late Ordovician (Zartman and 

Marvin, 1971).

Blue Hills Granite Porphyry.--The name Blue Hills Granite Porphyry 

of Chute (1966, 1969) is retained although the term Blue Hills Porphyry has 

been used by Naylor and Sayer (1976). Naylor and Sayer believe the Blue 

Hills to be the same age as the Quincy Granite, which Zartman and Marvin 

(1971) and Zartman (1977) have dated with the Cape Ann Complex as Early 

Silurian or Late Ordovician.

Bulgarmarsh Granite. The Bulgarmarsh Granite (Pollock, 1964) of 

southeastern Rhode Island and adjacent Massachusetts south of Fall River 

has been dated as early Paleozoic (Galloway, 1970), but it cannot be 

separated readily in the field from granite north of Fall River from which 

R. L. Zartman (written commun., 1979) has obtained a Proterozoic Z age 

similar to others in the southeastern Massachusetts batholith (see Kovach 

and others, 1977). The Bulgarmarsh, thus, is assigned a Proterozoic Z age.

Cape Ann Complex. The Cape Ann Granite is here renamed the Cape 

Ann Complex for the alkalic plutonic rocks (facies of Dennen, 1976) 

comprising the Cape Ann pluton (fig. 14). These are an unnamed alkalic 

granite and quartz syenite unit (Cape Ann Granite of Warren and McKinstry,
H66 CONTRIBUTIONS TO STRATIGRAPHY

1924, and of Toulmin, 1964), the Beverly Syenite, and the Squam Granite. 

Zartman and Marvin (1971) derived a radiometric age of 450 m.y.+25 m.y. 

from a concordia plot of U-Pb analyses of zircons from granite of the Cape 

Ann Complex and consider the Cape Ann to be Late Ordovician in age. A 

possibility exists, however, that because of the analytical uncertainty all or 

part of the complex might be Early Silurian (table 2); the Cape Ann, 

therefore, is considered to be Early Silurian or Late Ordovician in age.

Cherry Hill Granite. The Cherry Hill Granite, according to Toulmin 

(1964), who named it, intrudes the Wenham Monzonite and is, thus, at least 

slightly younger than the Wenham. The latter is considered with the 

Peabody, Granite to be part of the suite of alkalic plutons of eastern 

Massachusetts having Devonian radiometric ages (R. E. Zartman, written 

commun., 1981; Lyons and Kreuger, 1976, p. 94).

Dedham Granite. The name Dedham Granodiorite (Emerson, 1917) 

was changed to Dedham Granite (Wones, 1978) because most of the rock 

mapped as Dedham is granite according to the Streckeisen (1973) 

classification.

Esmond Granite. The Esmond Granite (Quinn and others, 1948) is 

Proterozoic Z in age (Hermes and others, 1981). It has similar spatial and 

textural similarities to the Proterozoic Z granites of southeastern 

Massachusetts and northern Rhode Island. Its age, thus, is changed from 

Late Ordovician or older to Proterozoic Z. The Esmond extends from Rhode 

Island into Massachusetts in the Blackstone area.

Grant Mills Granodiorite. The Grant Mills Granodiorite (Warren and 

Powers, 1914) is gradational into the Esmond according to Quinn (1971, p. 29) 

and here is assigned a Proterozoic Z age (Hermes and others, 1981). The 

Grant Mills does not project into Massachusetts, although it is shown in 

Rhode Island on the bedrock geologic map of Massachusetts (Zen and others, 

1981).

Hope Valley Alaskite Gneiss. The Hope Valley Alaskite Gneiss 

(Moore, 1958) is continuous from Rhode Island and Connecticut into 

Massachusetts in the Rhode Island batholith (anticlinorium of Rodgers, 

1970). Recent age determinations (Day and others, 1980; Hermes and others, 

1981) indicate a Proterozoic Z rather than Mississippian(?) or older age for 

this unit.

Milford Granite. U-Th-Pb radiometric age determinations on zircons 

from the Milford Granite (Emerson and Perry, 1907) by R. E. Zartman and 

R. S. Naylor (written commun., 1978) indicate a Proterozoic Z age. Its age 

designation of Proterozoic Z to early Paleozoic, thus, is changed to: 

Proterozoic Z. Although Emerson and Perry originally extended the Milford 

Granite into Rhode Island, Quinn (1971) does not recognize the Milford 

there. Granite that Emerson mapped as Milford in Rhode Island is mapped 

now mostly as Esmond Granite (see Quinn, 1971, p. 29). The Milford Granite, 

thus, is restricted geographically to Massachusetts.

Northbridge Granite Gneiss. Rocks formerly mapped as Northbridge 

Granite Gneiss (Emerson, 1917) have been found to be part of either the
RICHARD GOLDSMITH AND OTHERS H67

Scituate Granite Gneiss or the Ponaganset Gneiss (H. R. Dixon, unpub. data, 

1978), and the name Northbridge herewith is abandoned.

Peabody Granite. Zartman and Marvin (1971) considered the Peabody 

Granite (Clapp, 1910; Toulmin, 1964) to be the same age as the Quincy and 

former Cape Ann Granites on the basis of radiometric age determinations by 

several methods. However, subsequent work by R. E. Zartman (oral 

commun., 1979 and cited in Lyons and Kreuger, 1976, p. 94) has indicated 

that the Peabody is approximately 370 m.y. old. The Peabody, therefore, is 

assigned a Middle Devonian age.

Ponaganset Gneiss. The Ponaganset Gneiss (Quinn, 1967) is part of 

the granite gneiss terrane of the Rhode Island batholith that extends from 

Rhode Island and Connecticut into Massachusetts. Its age is considered to be 

Proterozoic Z, the same as the Hope Valley Alaskite Gneiss and Scituate 

Granite Gneiss, because of its similar gneissic character and intimate field 

relations with those rocks.

Scituate Granite Gneiss. The Scituate Granite Gneiss (Quinn, 1951) is 

Proterozoic Z in age on the basis of radiometric age determinations 

mentioned by Day and others (1980) and determinations by R. E. Zartman 

and R. S. Naylor (written commun., 1978). Hermes and others (1981), 

however, have shown that rock mapped as Scituate in central Rhode Island is 

Devonian. The Scituate, like the Hope Valley Alaskite Gneiss and the 

Ponagansett Gneiss, extends into Massachusetts in the Rhode Island 

batholith.

Sharon Syenite. The Sharon Syenite (Emerson, 1917) appears to have 

been produced by interaction between Dedham Granite and older gabbro and 

diorite. Its age, thus, is changed from Devonian or older to: Proterozoic Z.

Squam Granite. The Squam Granite (Clapp, 1910, 1921) is a facies of 

the Cape Ann Complex (Dennen, 1976) and, thus, is Early Silurian or Late 

Ordovician in age (Zartman and Marvin, 1971).

Topsfield Granodiorite. The age designation for the Topsfield 

Granodiorite (Toulmin, 1964) is changed from middle Paleozoic to 

Proterozoic Z on the basis of a K-Ar age of 640 m.y. on hornblende obtained 

from a dioritic phase of the Topsfield by Zartman and Naylor (1972; see also 

Shride, 1976, p. 151).

Wenham Monzonite. The Wenham Monzonite (Toulmin, 1964) is 

considered to be part of the suite of alkalic plutonic rocks of eastern 

Massachusetts having Devonian radiometric ages (Zartman, 1977; Lyons and 

Kreuger, 1976, p. 94). R. E. Zartman (written commun., 1981) obtained a 

Pb-U age of 395 m.y.+20 m.y. on zircon from the Wenham Monzonite, and it 

is thus assigned an Early Devonian age.

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H68 CONTRIBUTIONS TO STRATIGRAPHY

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RICHARD GOLDSMITH AND OTHERS H69

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H70 CONTRIBUTIONS TO STRATIGRAPHY

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RICHARD GOLDSMITH AND OTHERS H71

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H72 CONTRIBUTIONS TO STRATIGRAPHY

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scale 1:250,000.
CONTRIBUTIONS TO STRATIGRAPHY H73

MAUZY FORMATION, A NEW STRATIGRAPHIC UNIT 

OF PERMIAN AGE IN WESTERN KENTUCKY

By Thomas M. Kehn, John G. Beard , and 

Alien D. Williamson 1

ABSTRACT

The Mauzy Formation herein is named and defined as a rockstratigraphic unit in the western Kentucky coal field. Paleontological 

studies of the uppermost strata of the Sturgis Formation indicate that they 

are, at least in part, of Early Permian age, and they are reassigned to the 

Mauzy Formation. These strata are preserved in a fault block in the Sturgis, 

Union County, Ky., area. Lower Permian strata are unknown elsewhere in 

the Eastern Interior (Illinois basin) coal field area but probably covered part 

or all of this area prior to being eroded. The type section of the Mauzy 

Formation consists of interbedded shale, siltstone, and limestone, with minor 

amounts of sandstone and coal. It has a known thickness of about 390 ft but 

may be as much as 1,300 ft thick, as suggested by projected structural 

data. The Mauzy Formation conformably overlies the Sturgis Formation; the 

contact between the formations is at the base of a predominantly limestone 

sequence, in which Permian-age fusulinids have been identified, and above a 

sequence of shale, siltstone, sandstone, and coal that contains spores and 

pollen of Pennsylvanian age.

INTRODUCTION

Detailed geologic investigations supported by core drilling in the 

Bordley 7 l/2-min quadrangle (Kehn, I975a) and the Sturgis 7 l/2-min 

quadrangle (Kehn, I975b) have revealed a small down-faulted structural 

block of the Rough Creek fault system that contains a stratigraphic section 

more than 3.600 ft thick that was assigned to the Pennsylvanian System by 

Kehn (1973). Glenn (I9l2a,b; 1922) and Lee (1916) reported the 

Pennsylvanian section to be much thinner (fig. 15) and, because of the 

paucity of stratigraphic and structural control, did not recognize these 

younger strata in their reports of this area. Dunbar and Henbest (1942) 

summarized information on fusulinid-bearing horizons in the Illinois portion 

of the Eastern Interior coal field area and reported that fusulinids from the 

uppermost marine limestone beds were of Late Pennsylvanian age. They also 

stated that equivalent strata might be present in western Kentucky.

A core drilling program in the western Kentucky coal field conducted 

by the Kentucky Geological Survey was concluded recently. The core hole 

Gil-30 was taken from the fault block in which the thickest Pennsylvanian 

section had been identified. Samples of limestone from this core were 

obtained for paleontological studies, and this report is based in part on the 

result of that investigation and in part on a revision of structural control 

from data obtained in the core drilling program and reinterpretation of the 

previous mapping.

'Kentucky Geological Survey, Henderson, KY 42420.

U.S. Geol. Survey Bull. 1529-H, 1982, p. H73-H86
H74 CONTRIBUTIONS TO STRATIGRAPHY

The rocks formerly assigned to the uppermost part of the Sturgis 

Formation herein are reassigned to the Mauzy Formation, a new stratigraphic unit that is all, or in part, of Early Permian age. A summary of the 

nomenclature is given in figure 15.

PREVIOUS NOMENCLATURE 

Sturgfs Formation

Recently, the nomenclature of the uppermost part of the rockstratigraphic section of Pennsylvanian age in western Kentucky was modified 

and renamed the Sturgis Formation (Kehn, 1973), (see fig. 15). Later 

mapping, in the Bordley and Sturgis quadrangles (Kehn, I975a,b) (see fig. 16), 

revealed about 470 ft of younger strata not previously described. These 

rocks, although containing a much greater percentage of limestone and 

calcareous siltstone than previously described, were included as part of the 

Sturgis Formation. The base of the limestone and calcareous siltstone 

sequence is proposed as the base of the Mauzy Formation and the top of the 

Sturgis Formation, which, as redefined, is about 2,039 ft thick.

The Sulphur Springs coal bed, about 200 ft below the top of the 

Sturgis Formation, is equivalent to or slightly younger than the Pittsburgh 

coal bed of the Appalachian area (R. A. Peppers, Illinois State Geological 

Survey, written commun., 1978). It is the youngest stratum of Late 

Pennsylvanian age for which paleontological data are available in the 

western Kentucky coal field.

NEW STRATIGRAPHIC UNIT 

Mauzy Formation (here named)

The area underlain by the Mauzy Formation largely is concealed by 

loess and alluvium. Hence, surface criteria for differentiating the Mauzy 

Formation from the Sturgis Formation for stratigraphic and paleontological 

purposes could not be found. The core from core hole Gil-30 (fig. 17) 

confirmed the existence of the thick limestone and calcareous siltstone beds 

previously reported by Kehn (I975a, b) and also provided material for 

paleontological studies of the contained fusulinids. Therefore, the composite 

type section for the formation is designated as the 340 ft of measured 

section from core hole Gil-30 drilled by the Kentucky Geological Survey and 

at least 50 ft of younger strata inferred to exist in a nearby ridge about I mi 

west of Cap Mauzy Lake (fig. 17), from which the name Mauzy is taken. The 

core hole was about 7 1/2 mi northeast of Sturgis, Ky., in the northwestern 

part of the Bordley quadrangle (see figs. 16 and 17 and p. H79 for additional 

location data). The core is on file at the core library of the Kentucky 

Geological Survey, Lexington, Ky.

A generalized description of the composite type section of the Mauzy 

is included in this report. A thin bed of limestone at a depth of 193.9-195.8 

ft (243.9-245.8 ft, p. H8I) contains a few large Triticites sp. of Early 

Permian age (Douglass, 1979). About 145 ft of strata below the fusulinidbearing limestone is assigned also to the Mauzy Formation because the 

strata are lithologically similar to rocks above the limestone.
LEE (1916)

||

* Q

o

CO

fc

LL 

CO

O

Cn

c

CO

o

5

/Top of section

\3eiger Lake coal bed

\Top of No. 11 coal bed 

/No. 9 coal bed

Carbondale Formation

GLENN (1922)'

«=£ 

o to

o

o

E

o

c

CD

F

cn

Top of section

_x £* *~~S~**^S~*^S >^-^~S^*^N_X^K^~X-/^>

\3eiger Lake coal bed

/Providence Limestone

'

/No. 9 coal bed

Carbondale Formation

KEHN (1973)

/Top of se

\

CO

HI

Q.

0

CO

u_

cn

O)

3

CO

xGeiger Lake 

Carthage Limest

xTop of No. 1

/-No. 9 coa

Carbondale F

FIGURE 15.-Nomenclature of Kehn and others (this report) and of previous reports. 

from Kehn (1973).
50 100 MILES 

I___I____I____I

50 ' 100 KILOMETERS

INDIANA

I

ILLINOIS

/ \ W

M0<

PL .

KENTUCKY

- > TENNESSEE

37' 

301

EXPLANATION

O 

Kentucky Geological Survey core hole Gil-30

O 

Cities Service Oil Company stratigraphic test

hole Camp Breckinridge 1801

Fault U, upthrown side Area underlain by 

Mauzy Formation

88"00' 

 I 

37° 

37' 

30"

Morganfield

STURGIS QUADRANG

FIGURE 16.-Western Kentucky coal field, type area of the Mauzy Formation, and loc
THOMAS M. KEHN AND OTHERS H77

87°52'30"

Alluvium and loess not shown

1 MILE

.5 1 KILOMETER 

EXPLANATION

Mauzy Formation

}

O, *r 

^1 

-g § 

£^> 

2 c 

^8 §

Contact

Coal bed approximately located 

Dotted where concealed

Fault approximately located Bar 

and ball on downthrown side. 

Triangle indicates locality where 

fault was exposed

ii

2 < W >

*

Structure contours drawn on base 

of No. 9 coal bed Dashed 

where projected. Arrow indicates 

direction of dip. Contour interval 

100 feet. Some fault-block areas 

not contoured

O

Core hole or drill hole Core hole 

Gil-30 designated as part of 

composite type section of Mauzy 

Formation. Drill hole CS-1801 

designated as part of composite 

type section of Sturgis Formation 

(Kehn, 1973)

-K 

Caved adit

Strike and dip of bed Coal bed outcrop

FIGURE 17. -Area underlain by the Mauzy Formation, western Kentucky. Modified from

Kehn (1975a, b).
H78 CONTRIBUTIONS TO STRATIGRAPHY

The Mauzy Formation is composed of interbedded shale, siltstone, 

limestone, and sandstone. Shale and siltstone, the dominant rock types in 

the cored section, make up about 70 percent of the formation. The shale and 

siltstone, generally interlaminated, are commonly light gray to black or 

green to greenish gray. It is poorly to well laminated in even to wavy beds, 

except for steep crossbeds at a depth of 69.0-80.7 ft in the cored section 

(see p. H80). It also contains a few thin limestone and sandstone beds. The 

shale and siltstone generally are calcareous and micaceous along bedding 

surfaces. A coal bed and two thin carbonaceous shale beds are reported in 

the lower part of the cored section.

Limestone makes up about 25 percent of the Mauzy Formation. In the 

Sturgis Formation, limestone makes up less than 5 percent of the formation 

(Kehn, 1973, p. B8). The limestone of the Mauzy Formation is generally light 

gray to tan to buff. It is mostly very fine to fine grained and clayey to silty 

where it grades into or is interbedded with shale or siltstone. These 

calcareous sequences have been described as a pelmicrite by Dever and 

Macucuown (personal commun., 1978), a lithology not common to the 

western Kentucky coal field. The limestone is mostly even bedded and is as 

much as 10 ft thick. Marine fossils have not been recognized except for the 

fusilinids in the thin limestone bed near the middle of the cored section.

Sandstone makes up less than 5 percent of the formation. It is 

medium gray and fine grained. The sandstones are generally thin bedded; 

crossbedding, cut-and-fill structures, and interlaminations of shale and 

siltstone are common.

Coal is a minor constituent of the Mauzy Formation, as only three 

very thin coaly or carbonaceous shale beds were found in the lower part of 

the cored section. Additional coal beds could be in the loess-covered 50 ft 

of the type section lying above core hole Gil-30.

The total thickness of the formation is not known because of 

structural uncertainties and probable erosion of the top part of the section 

within the fault block. The formation may be as much as 1,300 ft thick as 

indicated by projected structure contours drawn on the No. 9 coal bed 

(fig. 17), which is widely used in western Kentucky as a structural datum. A 

total thickness of 1,300 ft or more for the Permian in western Kentucky 

would not be improbable as shown by McKee and others (1967, pi. 7). 

However, the structure is probably more complex than that shown (fig. 17). 

The strata may have dips more or less than those projected, or there could 

be a reversal of dip direction, and the 390 ft described here might be the 

maximum thickness preserved in the fault block and be essentially the 

maximum thickness deposited in the Eastern Interior region.

CONTACTS 

Lower boundary of Mauzy Formation

The Mauzy Formation appears to overlie the Sturgis Formation 

conformably and may intergrade with it. Deposition is assumed to have been 

continuous from one formation to the other as no evidence of a 

disconformity is seen in the core. This contact is here arbitrarily placed at 

the base of the limestone sequence in the uppermost 340 ft (390.0 ft of the
THOMAS M. KEHN AND OTHERS H79

described section, p. H80-H82) of strata cored at the core hole Gil-30 

locality. Such placement of the contact was made because the core contains 

a much greater percentage of limestone and calcareous shale above and a 

much greater percentage of sandstone and coal below.

The upper limit of the Mauzy Formation is not defined because it has 

been removed by erosion or is present only in the western portion of the 

fault block (fig. 17) where stratigraphic and structural control is not 

available to determine its placement. Younger rocks, if present, have been 

removed by erosion or are covered by Quaternary alluvium or Pleistocene 

loess in the western portion of the fault block.

Lower boundary of the Permicn System

The boundary between the Pennsylvanian and Permian Systems cannot 

be defined precisely because sufficient paleobotanical and paleontologtcal 

data are lacking. For convenience, the systemic boundary is tentatively 

placed at the proposed contact between the Mauzy and Sturgis Formations in 

core hole Gil-30. This differentation is based in part on gross lithologic 

character and on age differences of beds above and below the boundary.

The Sulphur Springs coal bed, about 200 ft below the boundary, is 

reported (R. A. Peppers, written commun., 1978) to be equivalent to or 

younger than the Pittsburgh coal bed and is presently the youngest coal bed 

of Late Pennsylvanian age identified in the western Kentucky section. The 

unnamed limestone, about 140 ft above the boundary, contains a few 

fusulinids of Early Permian age. Because deposition appears to have been 

continuous, all or part of the 340 ft of stratigraphic section between the 

Sulphur Springs coal bed and the fusulinid-bearing limestone bed mentioned 

earlier could be assigned to a transition zone or the boundary placed 

elsewhere within this interval of the section. Similarly, rocks at the 

Pennsylvanian-Permian boundary in the Appalachian area are gradational, 

and the contact is arbitrarily chosen (McKee and others, 1967, p. 36), or it is 

not precisely defined (Henry and others, 1979, p. 85).

LOCATION OF DRILL HOLES

(fig. 17)

[Core hole Gil-30; 300 ft from south line and 1,650 ft from east line of 

Carter coordinate section 13, N-20, or 2,800 ft from north boundary 

and 700 ft from west boundary of Bordley 7 l/2-min quadrangle, Union 

and Webster Counties, Ky. Surface elevation 455 ft above mean sea 

level. Core log datum 455 ft above mean sea level. Drilled 19761

[Cities Service Oil Company, stratigraphic test hole, drill hole CS-I80I, 700 

ft from south line and 600 ft from west line of Carter coordinate 

section 12, N-20, or 2,150 ft from north boundary and 3,150 ft from 

west boundary of Bordley 7 l/2-min quadrangle, Union and Webster 

Counties, Ky. Surface elevation 520 ft above mean sea level. Driller's 

log and geophysical electric log datum 526 ft above mean sea level. 

Drilled 19651
H80 CONTRIBUTIONS TO STRATIGRAPHY

COMPOSITE TYPE SECTION OF THE MAUZY FORMATION

[This composite type section includes 50 ft of strata that is inferred above 

the top of the cored section at the drill hole locality. Approximately 1,000 

ft of additional strata may be present as shown by the structure (fig. 17). 

However, no lithologic data are available, and structural control is 

uncertain; therefore, no description can be given for this part of the 

section. The following descriptive log is generalized from the core 

description by personnel of the Kentucky Geological Survey. The detailed 

descriptive log and core can be studied at that Survey, in Lexington, Ky.]

Unit Depth

(feet) 

Permian System

Mauzy Formation:

Surface, includes loess, soil and bedrock probably similar

to rock types described below ......................... 0-69.0

Shale, medium-gray to greenish-gray, slightly silty with

siltstone laminations dipping 10-20°. .................. 69.0-80.7

Sandstone, medium-gray, fine-grained; thin dark shale laminations at top, thicker toward base; base sharp ........... 80.7-106.1

Shale, gray to dark-gray, calcareous .................. 106.1-107.9

Limestone, gray to buff, finely crystalline to dense, slightly

clayey, calcite-filled fractures .................... 107.9-113.3

Shale, medium-gray, calcareous...................... II 3.3-113,8

Limestone, gray to buff ........................... II 3.8-114.8

Shale, medium-gray to greenish-gray, clayey at top, thin beds

of limestone at base ............................ II4.8-120.6

Shale, medium-gray, clayey, calcareous toward base ....... 120.6-124.1

Limestone, buff to gray, finely crystalline to dense; clayey

toward base .................................. 124.1-126.7

Shale, medium-gray, clayey. ........................ 126.7-128.9

Limestone, light-gray to tan, dense; calcite-filled fractures 

near top; green to gray shale parting 0.25 ft thick in 

middle of unit ................................ 128.9-132.7

Shale, light-gray to greenish-gray .................... 132.7-133.5

Limestone, buff to gray, clayey; becoming more shaley

toward base .................................. 133.5-139.0

Shale, dark-gray, calcareous ........................ 139.0-140.0
THOMAS M. KEHN AND OTHERS H81

Limestone, light-gray to tan to buff, dense; scattered

fractures, argillaceous in part ..................... 140.0-147.9

Shale, dark-gray, calcareous; few thin lenses of medium-gray

limestone in basal part .......................... 147.9-150.0

Limestone, medium-gray; argillaceous, dense ............ 150.0-159.9

Shale, gray to greenish-gray, calcareous; scattered

limestone nodules.............................. 159.9-170.8

Limestone, medium-gray; argillaceous, dense ............ 170.8-172.2

Shale, dark-gray, calcareous ........................ 172.2-176.1

Limestone, light-gray to tan to buff; argillaceous,

dense; dark-gray to greenish-gray shale partings ........ 176.1-202.8

Shale, greenish-gray to dark-gray, thinly laminated 

in part, silty; few thin laminations of very fine 

grained sandstone in middle of unit ................. 202.8-243.9

Limestone, light- to medium-gray; very argillaceous; 

fossiliferous with a few fusulinids of a large Triticites 

sp. of Early Permian age ......................... 243.9-245.8

Shale, dark-gray, thinly laminated; few siltstone laminations

near base.................................... 245.8-252.8

Sandstone, light-gray, very fine grained, calcareous; scattered

clay and shale nodules and laminations ............... 252.8-253.5

Shale, very dark gray, clayey, carbonaceous ............. 253.5-266.5

Limestone, tan to buff, finely crystalline to dense; fractured, 

nodular appearance, interbedded with greenish-gray to gray 

shale ....................................... 266.5-290.9

Shale, gray to greenish-gray, poorly bedded ............. 290.9-295.0

Shale, black, carbonaceous ......................... 295.0-295.1

Shale, gray to greenish-gray; occasional silt laminations,

limestone nodules at top and base .................. 295.1-325.0

Shale, dark-gray; occasional silt laminations. ............ 325.0-373.1

Coal, bony shaly near top .......................... 373.1-374.1

Shale, dark-gray to green, calcareous. ................. 374.1-375.0

Limestone, brown to tan, finely crystalline to dense ....... 375.0-376.8

Shale, dark-gray................................. 376.8-377.2
H82 CONTRIBUTIONS TO STRATIGRAPHY

Limestone, brown to tan; argillaceous toward base ........ 377.2-379.1

Shale, dark-gray ................................. 379.1-380.0

Limestone, light-gray to brown; dense, argillaceous ....... 380.0-388.2

Shale, dark-gray, calcareous ........................ 388.2-389.5

Limestone, light-gray to brown; dense, argillaceous.

The contact between the Mauzy and the Sturgis Formations is 

arbitrarily placed at base of this unit. The boundary between 

the Permian and the Pennsylvanian Systems also is placed 

tentatively at this contact ....................... 389.5-390.0

SECTIONS OF THE STURGIS FORMATION 

Upper part of the section

[This part of the composite section includes 200 ft of strata described from 

the core taken at the core hole Gil-30 locality and at the stratigraphic test 

hole, drill hole CS-I80I, locality. It corresponds to the 70- to 270-ft portion 

of the upper part of the section of the Sturgis Formation (Kehn, 1973, 

p. BII-BI2). The systemic boundary between the Permian and the 

Pennsylvanian Systems may be within this unit]

Unit Depth

(feet)

Pennsylvanian System 

Upper Pennsylvanian Series 

Sturgis Formation (in part):

Shale, green to gray, calcareous; clayey and brown to reddish

near middle and silty at base ...................... 390.0-395.9

Sandstone, medium-gray, very fine grained;

argillaceous .................................. 395.9-402.4

Shale, dark-gray ................................. 402.4-410.0

Shale, very dark gray to black; argillaceous; scattered 

limestone bands and nodules; carbonaceous in 

upper part ................................... 410.0-440.5

Coal, bright- and dull- banded; fine pyrite and calcitefilled veins at top .............................. 440.5-442.3

Shale, medium-gray, clayey, non bedded. ............... 442.3-443.3

Coal, dull to bright, fusain partings; bony with

carbonaceous shale partings at top and base; calcite

laminations in bony coal at base ................... 443.3-454.3

Shale, medium-gray, clayey, non bedded; plant impressions

at top; limestone nodules in lower part. .............. 454.3-468.8
THOMAS M. KEHN AND OTHERS H83

Shale, medium-gray, and limestone, tan, dense; silty toward

base ....................................... 468.8-480.1

Shale, dark-gray; with laminations of light-gray siltstone and

light-gray, fine-grained sandstone at base ............ 480.1-490.0

Sandstone, light- to medium-gray, fine-grained. .......... 490.0-493.3

Shale, greenish-gray to black; carbonaceous at base; pyrite

nodules and laminations ......................... 493.3-500.8

Coal, dull to bright, much fusain; pyrite bands on pyrite 

or on cleat; much bony coal and carbonaceous shale 

bands. ...................................... 500.8-505.8

Shale, medium-gray, non bedded; calcareous, with white

limestone nodules .............................. 505.8-520.4

Limestone, light-gray to gray, finely crystalline to

dense. ...................................... 520.4-526.0

Shale, medium-gray; scattered silty and calcareous

laminations and nodules ......................... 526.0-538.0

Shale, black, carbonaceous; few pyrite nodules ........... 538.0-541.1

Sandstone, medium-gray, fine- to medium-grained; scattered 

thin, carbonaceous shale laminations, argillaceous; 

sandy at top .................................. 541.1-556.5

Shale, dark-gray; scattered silty laminations ............ 556.5-565.1

Shale, black, carbonaceous, fissile .................... 565.1-567.1

Limestone, brown to gray, finely crystalline to dense; in beds 

1-2 ft thick separated by dark-gray to black carbonaceous 

shale beds 0.2-0.9 ft thick ........................ 567.1-572.8

Shale, dark-gray to black; calcareous with limestone 

laminations at top, carbonaceous and bony coal at 

base ....................................... 572.8-589.0

Lower part of the section

[This part of the composite section includes a modified log description of 

about 1,839 ft of the Sturgis Formation (Kehn, 1973, p. BI2-B23). Depth to 

described units modified to provide continuity]
H84 CONTRIBUTIONS TO STRATIGRAPHY

Unit Depth

(feet)

Pennsylvanian System 

Middle Pennsylvanian Series 

Sturgis Formation (in part):

Coal, dull to brightly banded. The Sulphur Springs coal bed 

(Kehn, 1973, p. BI2, 268-270 ft) contains a spore assemblage 

that is equivalent to or younger than the Pittsburgh coal bed 

(R. A. Peppers, written commun., 1978) ................. 589-591

Siltstone, sandstone, shale, limestone, coal, and underclay: 

siltstone, light- to dark-gray; interbedded with sandstone 

and shale; sandstone, light-gray, very fine to fine-grained; 

shale, light-gray to black; carbonaceous; limestone, brown 

and gray, dense; silty and shaley; coal, impure, generally 

in thin beds; underclay, light- to dark-gray .............. 591-1,416

Coal (Geiger Lake coal bed), bright ................... 1,416-1,417

Siltstone, shale, sandstone, limestone, and coal: siltstone, 

light- to dark-gray; shale, light-gray to black, clayey 

to sandy; sandstone, light-gray, interbedded with shale 

and siltstone; limestone, medium-gray; coal, 

thin, generally impure. Lisman coal bed, 6 in thick at 

base ....................................... 1,417-1,776

Siltstone, shale, sandstone, limestone, and coal: rock types 

similar to those described above. No. 18 coal bed, thin, 

in middle of unit. .............................. 1,776-1,957

Limestone (Carthage Limestone Member), light-olive-gray,

dense, fossiliferous............................. 1,957-1,964

Shale, siltstone, sandstone, limestone, coal, and underclay: 

rock types similar to those described above. Unit 

includes three named coal beds and the Madisonville Limestone 

Member, a single bed 5 ft thick at base .............. 1,964-2,248

Siltstone, sandstone, shale, limestone, coal, and underclay: 

rock types similar to those described above. Unit includes 

four named coal beds and the Providence Limestone Member at 

base. Basal part of claystone of the Providence Limestone 

Member in contact with top of the No. I I coal bed of the 

Carbondale Formation .......................... 2,248-2,429

SECTION OF THE CARBONDALE FORMATION

[This section includes a modified log description of about 124 ft of the 

Carbondale Formation penetrated by stratigraphic test hole, drill hole CS1801, Cities Service Oil Company. Depth to described units modified to 

provide continuity]
THOMAS M. KEHN AND OTHERS H85

Unit Depth

(feet)

Pennsylvanian System 

Middle Pennsylvanian Series 

Carbondale Formation (in part):

Coal, hard, bright; No. I 1 coal bed. No. I I coal bed at

depth of 2,047-2,051 ft .......................... 2,429-2,433

Claystone, light-gray; interbedded with light-gray siltstone

in lower part ................................. 2,433-2,436

Sandstone, light-gray, fine-grained ................... 2,436-2,440

Siltstone, light- to dark-gray, shaley .................. 2,440-2,464

Shale, light-gray to black at base. .................... 2,464-2,473

Coal, No. 10 coal bed ............................. 2,473-2,474

Shale and siltstone, dark-gray ....................... 2,474-2,487

Sandstone, medium-gray, fine-grained ................. 2,487-2,522

Shale, dark-gray, silty; carbonaceous in lower part ........ 2,522-2,548

Coal, bright, hard; No. 9 coal bed .................... 2,548-2,553

REFERENCES CITED

Douglass, R. C., 1979, The distribution of fusulinids and their correlation 

between the Illinois basin and the Appalachian basin, jri Palmer, J. E., 

and Dutcher, R. R., eds., Depositional and structural history of the 

Pennsylvanian System of the Illinois basin; pt. 2, invited papers, Field 

trip 2, Ninth International Congress of Carboniferous Stratigraphy and 

Geology: Illinois State Geological Survey, p. 15-20.

Dunbar, C. 0., and Henbest, L. G., 1942, Pennsylvanian Fusulinidae of 

Illinois: Illinois State Geological Survey Bulletin 67, 218 p.

Glenn, L. C., I9l2a, The geology of Webster County: Kentucky Geological 

Survey Report of Progress, 1910-1911, p. 25-35.

___I9l2b, A geological reconnaissance of the Tradewater River region, 

with special reference to the coal beds: Kentucky Geological Survey 

Bulletin 17, 75 p.

___1922, The geology and coals of Webster County: Kentucky Geological 

Survey, ser. 6, v. 5, 249 p.

Henry, T. W., Lyons, P. C., and Windolph, J. F., Jr., 1979, Upper 

Pennsylvanian and Lower Permian(?) Series in the areas of the proposed 

Pennsylvanian System stratotype, in Englund, K. E., Arndt, H. H., and
H86 CONTRIBUTIONS TO STRATIGRAPHY

.Henry, T. W., eds., Proposed Pennsylvanian System stratotype, Virginia 

and West Virginia: American Geological Institute, AGI Selected 

Guidebook Series, no. I, p. 81-85.

Kehn, T. M., 1973, Sturgis Formation (Upper Pennsylvanian), a new map unit 

in the western Kentucky coal field: U.S. Geological Survey Bulletin 

1394-B, 24 p.

___I975a, Geologic map of the Bordley quadrangle, Union and Webster 

Counties, Kentucky: U.S. Geological Survey Geologic Quadrangle Map 

GQ-1275.

___I975b, Geologic map of the Sturgis quadrangle, western Kentucky: 

U.S. Geological Survey Geologic Quadrangle Map GQ-1273.

Lee, Wallace, 1916, Geology of the Kentucky part of the Shawneetown 

quadrangle: Kentucky Geological Survey, ser. 4, v. 4, pt. 2, 73 p.

McKee, E. D., Oriel, S. S., and others, 1967, Paleotectonic maps of the 

Permian System: U.S. Geological Survey Miscellaneous Investigations 

Series Map 1-450, 164-p. text.
CONTRIBUTIONS TO STRATIGRAPHY H87

SIGNAL GRANITE (PRECAMBRIAN), WEST-CENTRAL ARIZONA

By Ivo Lucchitta and Neil Suneson 

INTRODUCTION

The name Signal Granite is given here to the granitic batholith that is 

at least 30 km in diameter and is best exposed in the northern part of the 

Artillery Mountains in the Artillery Peak 15-min quadrangle in west-central 

Arizona, between the ghost town of Signal (SW 1/4 sec. 9, T. 13 N., R. 13 W.) 

and Eagle Point (E 1/2 sec. 7, T. 12 N., R. 13 W.) (fig. 18). These exposures, 

considered its type locality, can be reached by jeep trail from near Signal 

and by the poorly maintained Old Alamo dirt road. Formalizing the name of 

the Signal Granite and describing its occurrence, geologic relations, 

lithology, and assigned age will make future references to this body simpler 

and more convenient.

GEOLOGIC SETTING AND LITHOLOGY

Geologic studies and field mapping on which this report is based 

indicate that the northern contact of the pluton is intrusive and occurs in the 

northwestern part of the Artillery Peak 15-min quadrangle and in the 

northeastern part of the Castaneda Hills 15-min quadrangle (fig. 18). The 

country rock consists of gneiss, schist, and plutonic rocks typical of the 

Precambrian terrane of the Hualapai Mountains of the southwestern edge of 

the Colorado Plateau. The eastern extent of the pluton is unknown because 

no mapping has been done in that direction. The western contact is poorly 

exposed and structurally complex and occurs approximately along the 

I 13° 50" west meridian in the Castaneda Hills quadrangle. Southward, the 

granite becomes increasingly sheared, altered, and mylonitized and is 

believed to form the protolith of the mylonitic quartz-feldspar gneiss of the 

Rawhide Mountains (Lucchitta and Suneson, unpub. data, 1978).

The granite is cut by veins of quartz, pegmatite, and aplite and by 

dikes of diabase, metarhyolite porphyry, and leucogranite. The Signal 

Granite is a light-gray to medium-brownish-gray, leucocratic to mesocratic, 

unfoliated to weakly foliated, typically massive, locally jointed and 

spheroidally weathered, medium- to coarse-grained porphyritic biotite 

granite or monzogranite. Phenocrysts are subequant, typically 2-3 cm long 

but as much as 5 cm in places, and composed of twinned potassium 

feldspar. The matrix consists of 0.5 cm plagioclase, gray quartz, and biotite 

that commonly is oxidized. Modal analysis of one stained slab has yielded 

the following mineral percentages: potassium feldspar, 36.2 percent; 

plagioclase, 25.7 percent; quartz, 27.5 percent; and biotite, 10.5 percent 

(Suneson, I960). A coarse-grained equigranular phase occurs locally. In 

places, the granite contains sparse xenoliths of melanocratic diorite, biotite 

schist, and leuco- to mesocratic gneiss. Leucocratic and mesocratic phases 

of the granite form bodies whose dimensions measure hundreds of meters. 

The granite is cut by numerous shear zones that are mineralized locally and 

show weak recrystallization. Zones of closely spaced subparallel joints are 

present in places.

U.S. Geol. Survey Bull. 1529-H, 1982, p. H87-H90
H88 CONTRIBUTIONS TO STRATIGRAPHY

1U°00'

-34°45' -

113°45' 113°30'

34°30'

34° 15

CASTANDEA HILLS 

15' QUADRANGLE

\\\\\\\\\\\\\\A\\

10 KILOMETERS

FIGURE 18.-Known outcrop areas of Signal Granite, west-central Arizona (stippled 

area). Area outlined with hachures has been mapped (Lucchitta and Suneson, unpub. 

data).
IVO LUCCHITTA AND NEIL SUNESON H89

AGE

Rocks here defined as the Signal Granite were assigned to the 

Precambrian by Lasky and Webber (1949) and by Wilson and others (1969). In 

both cases, however, the age assignment probably was made primarily on the 

grounds that basement plutonic and metamorphic rocks are Precambrian 

because a Precambrian age was assigned also to mylonite gneisses that are 

very different from those of the typical Precambrian basement of the area. 

These gneisses are known now to be of late Mesozoic or Tertiary age. 

Before the advent of routine radiometric dating, assignment of a 

Precambrian age on such assumptions was customary.

The Signal Granite still has not been dated radiometrically, although 

such dating is planned. Nevertheless, we assign it a Precambrian age on the 

following grounds:

1. It is lithologically and structurally similar to granites of known 

Precambrian age in Arizona (Hualpai [sic] Granite of Putnam and 

Burnham (1963); the Proterozoic Y Dells Granite, dated at 1.3 b.y. by 

Marvin and Cole (1978); granites near Bagdad, Ariz., described by 

Anderson and others (1955); the Oracle Granite of Peterson (1938); the 

Proterozoic Y Ruin Granite, which has a 1.4-b.y. age given by Ludwig 

and Silver (1977); and the quartz monzonite or granodiorite of Shride 

(1967)).

2. It is part of a basement terrane continuously traceable, without 

significant change in lithology, to rocks that underlie the Tapeats 

Sandstone (Lower and Middle Cambrian) of the Colorado Plateau 

margin, less than 30 km away.

3. It is cut by diabase and metarhyolite porphyry dikes that resemble 

similar rocks unconformably overlain by Cambrian strata in many parts 

of Arizona.

These criteria do not permit an unequivocal age assignment; the 

granite could be younger than Precambrian. In this unlikely case, however, 

the granite probably would be Late Cretaceous and (or) early Tertiary 

("Laramide") in age because that is the only known episode of postPrecambrian age that has produced large, deep-seated plutons in 

northwestern Arizona. Middle Tertiary plutons generally are small and 

hypabyssal.

REFERENCES CITED

Anderson, C. A., Scholz, E. A., and Strobell, J. D., Jr., 1955, Geology and ore 

deposits of the Bagdad area, Yavapai County, Arizona: U.S. Geological 

Survey Professional Paper 278, 103 p.

The Hualpai Granite of Putnam and Burnham (1963) was misspelled in 

publication; the correct spelling is Hualapai according to U.S. Geological 

Survey, Board on Geographic Names.
H90 CONTRIBUTIONS TO STRATIGRAPHY

Lasky, S. G., and Webber, B. N., 1949, Manganese resources of the Artillery 

Mountains region, Mohave County, Arizona: U.S. Geological Survey 

Bulletin 961, 86 p.

Ludwig, K. R., and Silver, L. T., 1977, Lead-isotope inhomogeneity in 

Precambrian igneous K-feldspars: Geochimica et Cosmochimica Acta, v. 

41, no. 10, p. 1457-1471.

Marvin, R. F., and Cole, J. C., 1978, Radiometric ages; Compilation A, U.S. 

Geological Survey: Isochron/West, no. 22, p. 3-14.

Peterson, N. P., 1938, Geology and ore deposits of the Mammoth mining 

camp area, Pinal County, Arizona: Arizona Bureau of Mines Bulletin 144, 

Geologic Series I I, 63 p.

Putnam, G. W., and Burnham, C. W., 1963, Trace elements in igneous rocks, 

northwestern and central Arizona: Geochimica et Cosmochimica Acta, v. 

27, no. I, p. 53-106.

Shride, A. F., 1967, Younger Precambrian geology in southern Arizona: U.S. 

Geological Survey Professional Paper 566, 89 p.

Suneson, Neil, 1980, The origin of bimodal volcanism, west-central Arizona: 

University of California at Santa Barbara, Ph.D. dissertation, 293 p.

Wilson, E. D., Moore, R. T., and Cooper, J. R., 1969, Geologic map of 

Arizona: Arizona Bureau of Mines and U.S. Geological Survey, scale 

1:500,000.
CONTRIBUTIONS TO STRATIGRAPHY H91

ADOPTION OF NAMES OF CERTAIN MEMBERS OF FORMATIONS 

IN THE HAMILTON GROUP (MIDDLE DEVONIAN) OF NEW YORK

By William A. Oliver, Jr. 

INTRODUCTION

Present understanding and nomenclature of Hamilton Group (Middle 

Devonian) rocks in New York date from Cooper (1930). The marine parts of 

the group in western and central New York are divided into four formations; 

in ascending order these are the Marcellus Shale, Skaneateles Shale, 

Ludlowville Shale (now changed to Formation), and Moscow Shale. These 

formations have long been used in U.S. Geological Survey publications as 

defined by Cooper. The history of usage through I960 is outlined in the 

lexicons of Wilmarth (1938) and Keroher and others (1966).

Cooper (1930) subdivided each of the Hamilton formations into 

numerous members, many of which have been adopted for U.S. Geological 

Survey usage as the need arose. Cooper's members have stood the test of 

time very well, but later workers have redefined a few units, and additional 

members have been named. Currently used member nomenclature is shown 

on the correlation chart of Rickard (1975), although Baird (1979) recently has 

modified the formational assignment of some members in western New York.

Recent work on coral biostratigraphy in New York (Oliver and Sorauf, 

1981) has indicated the need for U.S. Geological Survey adoption of 

additional member names as summarized in the following section.

NEW ADOPTIONS 

Kashong Shale Member (of Moscow Shale)

This name is adopted as originally defined by Cooper (1930, p. 231- 

232) and as used by subsequent workers (for example, Boardman, I960; p. 7; 

Rickard, 1964, 1975; Oliver and others, 1969; Baird, 1979, p. 12-14). Baird's 

recent description and interpretation is the most complete. The Kashong is 

underlain by the Menteth Limestone Member and the Portland Point 

Limestone Member of Cooper (1930) and is overlain by the Windom Member, 

all of the Moscow Shale.

The type section is in Kashong Creek on the west side of Seneca Lake, 

Yates County, where it is 24 ft thick (Cooper, 1930, p. 231).

Otisco Shale Member (of Ludlowville Formation)

This member is adopted as originally defined by Smith (1935, p. 45-47) 

and accepted by Cooper (m Cooper and others, 1942, chart). It was used 

with the same meaning by Oliver (1951), Rickard (1964, 1975), and Oliver and 

others (1969). The most recent description and discussion is by Grasso (1978, 

p. 144-146). The member is underlain by the Centerfield Limestone Member 

and overlain by the Ivy Point Member of Smith (1935), both of the 

Ludlowville Formation.

U.S. Geol. Survey Bull. 1529-H, 1982, p. H9I-H93
H92 CONTRIBUTIONS TO STRATIGRAPHY

The type section is in Millers Place ravine on the west side of Otisco 

Lake, I mi northwest of the former causeway, Cayuga County, where it is 

150 ft thick (Smith, 1935, p. 45).

Pompey Shale Member (of Skaneateles Shale)

This member is adopted as originally defined by Cooper (1930, p. 220- 

221) and as subsequently used by Rickard (1964, 1975) and by Oliver and 

others (1969). The member is underlain by the Delphi Station Member of 

Cooper (hi Cooper and others, 1942, chart; name replacing Delphi Member of 

Cooper, 1930) and is overlain by the Butternut Shale Member of Cooper (hi 

Cooper and others, 1942, chart; name replacing Berwyn Member of Cooper, 

1930), all of the Skaneateles Formation.

The type section is at the top of Pratt Falls, Onondaga County (Oran 

7 l/2-min quadrangle), where the member is 60 ft thick (Cooper, 1930, 

p. 220).

REFERENCES CITED

Baird, G. C., 1979, Sedimentary relationships of Portland Point and 

associated Middle Devonian rocks in central and western New York: 

New York State Museum Bulletin 433, 24 p.

Boardman, R. S., I960, Trepostomatous Bryozoa of the Hamilton Group of 

New York State: U.S. Geological Survey Professional Paper 340, 87 p.

Cooper, G. A., 1930, Stratigraphy of the Hamilton Group of New York: 

American Journal of Science, 5th ser., v. 19, p. I 16-134, 214-236.

Cooper, G. A., chairman, and others, 1942, Correlation of the Devonian 

sedimentary formations of North America chart no. 4 : Geological 

Society of America Bulletin, v. 53, no. 12, pt. I, p. 1729-1793.

Grasso, T. X., 1978, Benthic communities of the Ludlowville and Moscow 

Formations (upper Hamilton Group), in the Tully Valley, Onondaga 

County, ni New York State Geological Association Guidebook, 50th 

Annual Meeting: p. 143-172.

Keroher, G. C., and others, 1966, Lexicon of geologic names of the United 

States for 1936-1960: U.S. Geological Survey Bulletin 1200, 4,341 p.

Oliver, W. A., Jr., 1951, Middle Devonian coral beds of central New York: 

American Journal of Science, v. 249, p. 705-728.

Oliver, W. A., Jr., de Witt, Wallace, Jr., Dennison, J. M., Hoskins, D. M., and 

Huddle, J. W., 1969, Correlation of Devonian rock units in the 

Appalachian basin: U.S. Geological Survey Oil and Gas Investigations 

Chart OC-64.

Oliver, W. A., Jr., and Sorauf, J. E., 1981, Rugose coral biostratigraphy of 

the Devonian of New York and adjacent areas, jn Oliver, W. A., Jr., and 

Klapper, Gilbert, eds., Devonian biostratigraphy of New York; Part I,
WILLIAM A. OLIVER, JR. H93

International Subcommission on Devonian Stratigraphy: Washington, 

D.C., p. 97-105.

Rickard, L. V., 1964, Correlation of Devonian rocks in New York State: New 

York State Museum Map and Chart Series, no. 4, with text.

___1975, Correlation of the Silurian and Devonian rocks in New York 

State: New York State Museum Map and Chart Series, no. 24, 16-p. 

text, 4 sheets.

Smith, Burnett, 1935, Geology and mineral resources of the Skaneateles 

quadrangle: New York State Museum Bulletin 300, 120 p.

Wilmarth, M. G., 1938, Lexicon of geologic names of the United States 

(including Alaska): U.S. Geological Survey Bulletin 896, 2,396 p.

CONTRIBUTIONS TO STRATIGRAPHY H95

CORRELATION OF EASTFORD GNEISS WITH 

CANTERBURY GNEISS, EASTERN CONNECTICUT

By Maurice H. Pease, Jr.

Gregory (nn Rice and Gregory, 1906) assigned the name Eastford 

granite gneiss to a body of orthogneiss exposed mostly in the town of 

Eastford, Conn. He also mapped as Canterbury granite gneiss (irji Gregory 

and Robinson, 1907) several bodies of similar granitic orthogneiss, the 

largest of which underlies the western part of the town of Canterbury.

Dixon (1968) gives a comprehensive review of the historical 

background and geographic distribution of the Eastford Gneiss and 

Canterbury Gneiss, as they were termed at that time. She restricted use of 

the term Eastford Gneiss to the orthogneiss exposed in the Eastford 

quadrangle and northern part of the Hampton quadrangle and mapped (in 

Dixon and PessI, 1966) these rocks as a separate body not contiguous wifH 

exposures of similar orthogneiss to the south.

Dixon also recognized minor differences in mineral composition 

between this restricted body of Eastford Gneiss and typical Canterbury 

Gneiss stating that, "In general, the Eastford Gneiss contains more 

microcline and slightly more muscovite and less biotite and calcium-bearing 

accessory minerals such as epidote, allanite and sphene" (Dixon, 1968, p. 175) 

than the Canterbury. In addition to this mineralogical difference, it was 

postulated that the Eastford Gneiss has a relict primary foliation not present 

in the Canterbury Gneiss and that, on this basis, the Eastford is a separate 

and slightly older pluton (Dixon, 1968; Pease, 1972). Dixon (1968, p. 109), 

however, did recognize that the composition and mode of occurrence of the 

two gneisses were similar, and stated further that whether they constituted 

a single body was still not certain.

More recent detailed mapping in this area (fig. 19; Pease and Fahey, 

1978) has shown that the orthogneiss mapped as Eastford Gneiss in the 

Eastford quadrangle (Pease, 1972) and in the northwestern part of the 

Hampton quadrangle (Dixon and PessI, 1966) extends into the Spring Hill 

quadrangle where it is contiguous with rocks mapped as Canterbury Gneiss. 

These two rock units cannot be distinguished reliably in outcrop, and studies 

of core samples from drill holes in the critical area and of samples from a 

gas-transmission-line trench have shown no persistent differences between 

samples of Eastford and Canterbury (Pease, 1980). Furthermore, although no 

statistical assessment has been made, greater differences in mineral 

composition and degree of foliation have been observed within the various 

exposures of orthogneiss than the slight differences observed between the 

Eastford and the Canterbury.

Radiometric age determinations also indicate that the Canterbury and 

the Eastford are probably one and the same. Zartman (in Zartman and 

others, 1965) originally reported Rb-Sr whole-rock isochron ages for the 

Canterbury as 430 m.y.+20 m.y. and for the Eastford as approximately 380 

m.y. More recently, Zartman (personal commun., 1979), using zircons, 

derived 207Pb/206Pb data from Canterbury and Eastford samples that plot

U.S. Geol. Survey Bull. 1529-H, 1982, p. H95-H97
H96 CONTRIBUTIONS TO STRATIGRAPHY

72°00'

41°45'

I I i I

i i i r

5 KILOMETERS

5 MILES 

J

EXPLANATION

Fault

Thrust fault Sawteeth 

on upper plate

FIGURE 19.-Distribution of Canterbury Gneiss in the Eastford, Hampton, and Spring 

Hill quadrangles, New York. Geology modified from Pease (1978).
MAURICE H. PEASE, JR. H97

reasonably well as a linear array on a concordia diagram yielding an age of 

400 m.y.nJO m.y. Zartman (personal common., 1979) also redetermined the 

Rb-Sr whole-rock isochron ages by using more samples and more precise 

analytical techniques. He was able to derive a colinear single isochron 

diagram of 352 na.Y,+9 m.y. for all of the samples that is in close agreement 

with the ^u/Pb/^U6P~b age. Independent isochrons for the Canterbury and 

the Eastford yielded values of 403 m.y.jH28 m.y. and 389 m.y.jfl4 m.y., 

respectively. Each separate isochron is less colinear than the combined 

isochron, and they lie well within the margin of analytical error for a single 

isochron age. Zartman (personal commun., 1979) concluded that the 

Canterbury and the Eastford probably were intruded at the same time.

Thus, the criteria used to separate the body of orthogneiss mapped as 

Eastford from the several bodies of orthogneiss mapped as Canterbury 

appear to be insufficient to warrant the distinction. Use of the name 

Eastford Gneiss, therefore, is abandoned herein; and use of the name 

Canterbury Gneiss herein is extended geographically to include those rocks 

formerly mapped as Eastford.

REFERENCES CITED

Dixon, H. R., 1968, Bedrock geology of the Plainfield-Danielson area, 

Connecticut: U.S. Geological Survey Open-File Report, 308 p.

Dixon, H. R., and Pessl, Fred, Jr., 1966, Geologic map of the Hampton 

quadrangle, Windham County, Connecticut: U.S. Geological Survey 

Geologic Quadrangle Map GQ-468.

Gregory, H. E., and Robinson, H. H., 1907, Preliminary geological map of 

Connecticut: Connecticut Geological and Natural History Survey 

Bulletin 7, 39 p.

Pease, M. H., Jr., 1972, Geology of the Eastford quadrangle, Windham and 

Tolland Counties, Connecticut: U.S. Geological Survey Geologic 

Quadrangle Map GQ-1023, 3-p. text.

___1980, Geologic data obtained from core samples drilled in the vicinity 

of Chaplin, Windham County, Connecticut: U.S. Geological Survey 

Open-File Report 80-933, 34 p.

Pease, M. H., Jr., and Fahey, R. J., 1978, a reinterpretation of the 

stratigraphy and structure in part of eastern Connecticut [abs.]: 

Geological Society of America Abstract with Programs, v. 10, no. 2, 

p. 79.

Rice, W. N., and Gregory, H. E., 1906, The crystalline rocks of 

Connecticut: Connecticut Geological and Natural History Survey 

Bulletin 6, p. 39-156.

Zartman, R. E., Snyder, G. L., Stern, T. W., Marvin, R. S., and Bucknam, 

R. C., 1965, Implications of new radiometric ages in eastern 

Connecticut and Massachusetts: U.S. Geological Survey Professional 

Paper 525-D, p. DI-DIO.

CONTRIBUTIONS TO STRATIGRAPHY H99

REVISION OF UPPER CRETACEOUS NOMENCLATURE 

IN MONTANA AND SOUTH DAKOTA

By Dudley D. Rice, George W. Shurr, and 

Donald L. Gautier

Changes in Upper Cretaceous nomenclature are necessary to 

facilitate the presentation of results of recent and future stratigraphic and 

sedimentological studies in Montana and South Dakota. The changes pertain 

to the Belle Fourche Shale, Greenhorn Formation, and Mosby Sandstone 

Member of Cenomanian and Turanian Age and with the Groat Sandstone Bed 

of Companion Age (fig. 20).

In central Montana, the Belle Fourche Shale and Greenhorn Formation 

are redefined. Their contact is moved upward from the base of the Mosby 

Sandstone Member where the Mosby occurs (fig. 21) to the top of 

noncalcareous shale that overlies the Mosby. The change is based on 

lithology. Thus, the Mosby is removed from the Greenhorn and reassigned to 

the Belle Fourche. The Greenhorn Formation, as redefined, is composed 

primarily of calcareous shale and limestone, whereas the Belle Fourche Shale 

is mainly noncalcareous shale with minor siltstone and sandstone, 

particularly in the upper part.

In outcrop, the Mosby Sandstone Member commonly consists chiefly 

of two sandstone beds that contain a distinct gastropod fauna developed in 

the uppermost 10 m of the Belle Fourche (Cobban, 1953). The upper contact 

of the Mosby is the top of a unit of noncalcareous shale that overlies the 

sandstone beds and coincides with the top of the Belle Fourche Shale. As a 

result of detailed outcrop and subsurface studies, the Mosby hereafter is 

extended to include all sandstone beds developed in the Belle Fourche that 

are approximately confined to the upper 60 m. If more than one sandstone is 

present, the member also includes noncalcareous siltstone and shale between 

and above the sandstones. Logs in figure 22 show the presence of several 

sandstones in the Mosby in north-central Montana.

Sandstone that crops out 45 m below the top of the Gammon 

Ferruginous Member of Pierre Shale along the northern flank of the Black 

Hills has been named the Groat Sandstone Bed (Rubey, 1930). The term is 

not widely used and is hereby restricted to outcrop. The name Shannon 

Sandstone Member is hereby extended from Wyoming to the subsurface of 

east-central Montana and northwestern South Dakota as a member of the 

Gammon Shale and applied to sandstone equivalent to the Groat in the 

subsurface. This extension is justified because (I) the name Shannon was 

adopted earlier than the Groat (Wegemann, 1911), (2) the term Shannon 

commonly is used in the northern Great Plains, and (3) the sandstone in the 

subsurface of Montana and South Dakota correlates with the type Shannon of 

Wyoming (Parker, 1958) and lies within the same ammonite zones (Gill and 

Cobban, 1973). The name Shannon Sandstone Member in Montana and South 

Dakota is restricted to discontinuous but widespread sandstone bodies that 

are equivalent to and lie eastward (seaward) of more continuous sandstone 

beds in the Eagle Sandstone. The Shannon, as now used, is laterally 

continuous and was deposited in the same depositional environment as the

US. Geol. Survey Bull. 1529-H, 1982, p. H99-HI04
HIOO CONTRIBUTIONS TO STRATIGRAPHY

SERIES

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FORMATION/MEMBER

i&^a'^SlE? <^^f^^^ 

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Carlile Shale

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 ;: .* Mos'by .'.S f 

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1

Groat Sandstone BedVor 

Shannon Sandstone 

Member2

Gammon Ferruginous Member 

of Pierre ShaleVGammon 

Shale2

'Outcrop 

2Subsurface

FIGURE 20.-Upper Cretaceous rocks in east-central Montana and northwestern South

Dakota.
DUDLEY D. RICE AND OTHERS HIOI

nfio CANADA

7 |6 __ _114°_____ 

' UNITED^STATES

112°

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110° 108'

M O N T A N

106°

| NORTH

DAKOTA/160 

SOUTH

, 

_/\l 0 50 100 150 MILES

I I I . I

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0 50 100 150 200 KILOMETERS

FIGURE 21.-Areal distribution of Mosby Sandstone Member (lined pattern), northcentral Montana.
HI02 CONTRIBUTIONS TO STRATIGRAPHY

DEPTH 

METERS 

304.8

Greenhorn 

Formation .

Carlile 

Shale

1

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Belle

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Mosby

Sandstone

Member

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DEPTH 

FEET 

1000

- 1100

1200

- 1300

1400

FIGURE 22.-Electric log showing presence of several sandstones in Mosby Sandstone 

Member, north-central Montana.
DUDLEY D. RICE AND OTHERS HI03

Groat Sandstone Bed in outcrop. The approximate areal distribution of the 

Shannon Sandstone Member and Groat Sandstone Bed in Montana and South 

Dakota is shown in figure 23. Where the term Shannon Sandstone Member is 

applied in Montana and South Dakota, the Gammon is raised to the rank of 

formation and named the Gammon Shale. The Shannon remains a member of 

the Cody and Steele Shales in the Big Horn and Powder River Basins of 

Wyoming, respectively.

CANADA

114° 112

\ \ \ 

0 50 150 200 KILOMETERS

FIGURE 23. -Areal distribution of Shannon Sandstone Member (lined pattern) and Groat 

Sandstone Bed (dashed line), Montana and South Dakota.
H104 CONTRIBUTIONS TO STRATIGRAPHY

REFERENCES CITED

Cobban, W. A., 1953, Cenomanian ammonite fauna from the Mosby 

Sandstone of central Montana: U.S. Geological Survey Professional 

Paper 243-D, p. D45-D54.

Gill, J. R., and Cobban, W. A., 1973, Stratigraphy and geologic history of the 

Montana Group and equivalent rocks, Montana, Wyoming, and North 

and South Dakota: U.S. Geological Survey Professional Paper 776, 

37 p.

Parker, J. M., 1958, Stratigraphy of the Shannon Member of the Eagle 

Formation and its relationship to other units in the Montana Group in 

the Powder River Basin, Wyoming and Montana: Wyoming Geological 

Association, 13th Annual Field Conference Guidebook, Powder River 

Basin, p. 90-102.

Rubey, W. W., 1930, Lithologic studies of fine-grained Upper Cretaceous 

sedimentary rocks of the Black Hills region: U.S. Geological Survey 

Professional Paper 165-A, p. AI-A54.

Wegemann, C. H., 1911, The Salt Creek oil field, Natrona County, 

Wyoming: U.S. Geological Survey Bulletin 452, 87 p.
CONTRIBUTIONS TO STRATIGRAPHY H105

CHANDLER BRIDGE FORMATION-A NEW OLIGOCENE

STRATIGRAPHIC UNIT IN THE LOWER COASTAL PLAIN

OF SOUTH CAROLINA

By Albert E. Sanders , Robert E. Weems, and Earl M. Lemon, Jr.

ABSTRACT

The name Chandler Bridge Formation is introduced herein for a thin 

sequence of noncalcareous arenaceous beds i-'nat lies disconformably above 

the Ashley Member (Oligocene) of the Cooper Formation and disconformably 

below post-Oligocene deposits northwest of Charleston, S.C. A diverse 

fauna of well-preserved whales indicates that the Chandler Bridge is of late 

Oligocene (Chattian) age.

INTRODUCTION

The name Chandler Bridge Formation is introduced here for a 

sequence of noncalcareous arenaceous beds as much as 5 m thick that 

disconformably overlies the Ashley Member (Oligocene) of the Cooper 

Formation (Ward and others, 1979) in the Stallsville, Ladson, Johns Island, 

and Mount Holly 7 l/2-min quadrangles, Dorchester, Berkeley, and 

Charleston Counties, S.C. (fig. 24). The formation is disconformably 

overlain throughout most of this area by surficial Pleistocene deposits.

The Chandler Bridge Formation can be divided into three conformable 

beds: bed I, a basal, dark-yellowish-brown (IOYR 4/2) , clayey, slightly 

calcareous, fine-grained quartz-phosphate sand; bed 2, a middle, mediumgray (N5), clayey, noncalcareous, poorly compacted, fine-grained quartzphosphate sand; and bed 3, an upper, medium-gray (N5), clayey, 

noncalcareous, well-compacted, medium-grained quartz-phosphate sand. 

Phosphate nodules ranging from 10 to 50 mm in diameter are abundant in 

beds 2 and 3. Bed I occurs throughout the type area, but it is only sporadic 

elsewhere in the subcrop belt and may be discontinuous even within a single 

subcrop. Its maximum known thickness is 30 cm. Bed 2 ranges in thickness 

from 30 to 60 cm, whereas bed 3 may be as thick as 4 m. The maximum 

known thickness for the entire formation is about 5 m.

The beds described here as the Chandler Bridge Formation possibly 

were included in the Ladson Formation as defined by Malde (1959), but 

reevaluation of his detailed sections suggests that he did not actually 

penetrate the Chandler Bridge in any of his augered holes. Because the 

Chandler Bridge is preserved sporadically in low areas on the surface of the 

Cooper Formation, it is not surprising that these beds were not reported. 

Although generally similar in gross appearance to some of the Pleistocene 

sediments that overlie it, the Chandler Bridge Formation, unlike the 

Pleistocene sediments, contains abundant sand-sized rounded phosphate 

grains and has a much finer quartz-sand fraction. Its diverse fauna of

'Curator of Natural History, Charleston Museum, Charleston, SC 29401. 

Color designations are based on the "Rock-Color Chart" of the National 

Research Council (Goddard and others, 1948).

U.S. Geol. Survey Bull. 1529-H, 1982, p. H105-HI24
HI06 CONTRIBUTIONS TO STRATIGRAPHY

80°15'

EXPLANATION

Subcrop area of Chandler 

Bridge Formation

F Fossiliferous exposure

T Type locality

R1 Reference section

 Province boundaries

80°07'30"

SOUTH CAHl

79°52'30"

33°07'30"

32°52'30"

32° 45'

4 6 MILES

J_____|

I I I 

0246 KILOMETERS

FIGURE 24.-Report area, eastern South Carolina, including 7 Vz-minute quadrangles and 

known subcrop areas of the Chandler Bridge Formation. At the locality in the northwestern North Charleston quadrangle labeled with a question mark, Malde (1959) 

reported sand beneath the "upper Miocene Duplin Marl" (equivalent to lower Pliocene 

"Goose Creek Marl" of Sloan, 1908) that possibly belongs with the Chandler Bridge Formation. Other unfossiliferous but lithologically identical subcrops, penetrated during 

drilling in this area, are labeled with question marks and probably belong to this unit.
ALBERT E. SANDERS AND OTHERS H107

archaeocete and odontocete whales establishes the age of this unit as 

Oligocene (Sanders and others, 1979). The occurrence in the Chandler Bridge 

of only one genus and none of the species found in the underlying Ashley 

Member of the Cooper Formation (listed in Whitmore and Sanders, 1976) 

strongly suggests that a significant unconformit/ exists between these two 

units.

TYPE SECTION AND REFERENCE SECTIONS

The Chandler Bridge Formation is named here for exposures in a 

Charleston Museum paleontological excavation along Chandler Bridge Creek, 

0.7 km northwest of of the confluence of that creek with Eagle Creek, in the 

northeast quarter of the Stallsville 7 l/2-min quadrangle, Dorchester 

County, S.C. (figs. 24, 25). At the time of excavation, these beds were 

informally designated as the "Eagle Creek beds" (Whitmore and Sanders, 

1976), but this name has been abandoned as it has been used widely 

elsewhere in the geological literature and is preempted as a formal geologic 

name. Also, at the time of excavation, the recognizable lithologies were 

field designated "zone I" (equivalent to Ashley Member, Cooper Formation), 

"zone 2" (equivalent to bed I of this report), "zone 3" (equivalent to bed 2), 

and "zone 4" (equivalent to bed 3). This terminology appears in figure 26, a 

photograph taken at the time of excavation. These zones do not have formal 

status.

Nowhere does this unit crop out naturally, but data from 

channelization ditches and borings indicate that the unit is more or less 

continuous throughout the northeast quarter of the Stallsville quadrangle 

(fig. 24). Because all these manmade outcrops are evanescent, the northeast 

quarter is designated as a type area containing the type section. A sandpit 

southeast of the Creekside Trailer Park in the north-central part of the 

StalCsville quadrangle and an excavation site in the northeast quarter of the 

Ladson 7 l/2-min quadrangle are designated here as reference sections 

(fig. 24), although at these localities all the constituent beds are not present.

TYPE SECTION OF THE CHANDLER BRIDGE FORMATION

[Measured at the Charleston Museum paleontologic excavation site 0.7 km 

northwest of the confluence of Chandler Bridge Creek and Eagle Creek, 

30m northeast of Chandler Bridge Creek, Stallsville 7 l/2-min quadrangle 

(northwest of Charleston), Dorchester County, S.C. Surface altitude is about

6m].

Unit Description Thickness (meters)

Pleistocene deposits: 

7. Topsail .........................................0.15

6. Hardpan, clayey subsoil.............................. 0.35

5. Quartz sand, medium-gray (N5), medium-grained, angular, 

massive, clayey, noncalcareous, well-compacted; basal 

quartz and phosphate pebble bed 0.05 m thick. ............ .0.65
HI08 CONTRIBUTIONS TO STRATIGRAPHY

UNIT

O O.

^ Disconformity/ 

(approximate altitude is 3 m above sea level)

Poorly consolidated limestone

3 FEET 

1 METER

FIGURE 25.-Paleontologic excavation site designated as the type section of the Chandler 

Bridge Formation, lower coastal plain of South Carolina. No vertical exaggeration.
ALBERT E. SANDERS AND OTHERS H109

Chandler Bridge Formation (Oligocene):

4. Quartz-phosphate sand (bed 3 = "zone 4"), medium-gray 

(N5), medium-grained, massive, clayey, noncalcareous, 

well-compacted; abundant subrounded to angular lumps 

of phosphate ..................................... 0.55

3. Quartz-phosphate sand (bed 2 = "zone 3"), medium-gray 

(N5), fine-grained, bioturbated, clayey, noncalcareous, 

poorly compacted; abundant subrounded to angular lumps 

of phosphate ..................................... 0.40

2. Quartz-phosphate sand (bed I = "zone 2"), dark-yellowishbrown (10 YR 4/2), fine-grained, massive, clayey, slightly 

calcareous, poorly compacted; rests on a sharply defined, 

undulatory surface ............................. 0.20-0.30

Total thickness of the Chandler Bridge Formation............. 1. 15-1.25

Cooper Formation, Ashley Member (Oligocene):

I. Limestone ("zone I"), light-olive-brown (5 Y 5/6),

fine-grained, bioturbated, well-compacted but poorly

consolidated; contains fine-grained phosphate and quartz

sand; top surface burrowed and filled with matrix of

overlying unit................................. 0.30-0.40

REFERENCE SECTION I OF THE CHANDLER BRIDGE FORMATION

[Measured 0.8 km southeast of S.C. Route 165 bridge over Sawmill BranchDorchester Creek in bank of borrow pit southeast of Creekside Trailer Park, 

in the Stallsville 7 l/2-min quadrangle (northwest of Charleston), Dorchester 

County, S.C. Surface altitude about 6m.]

Unit Description Thickness (meters) 

Pleistocene deposits: 

6. Topsail ........................................ .0.15

5. Quartz sand, medium-gray (N5), medium-grained, angular, 

massive, clayey, noncalcareous, we 11-compacted; basal 

quartz and phosphate pebble bed 0.05 m thick.............. 0.60

Chandler Bridge Formation (Oligocene): 

4. Absent (bed 3) .................................... 0.00

3. Quartz-phosphate sand (bed 2), medium-gray (N5), finegrained, bioturbated, clayey, noncalcareous, poorly 

compacted; abundant subrounded to angular lumps of 

phosphate ....................................... 0.70
HI 10 CONTRIBUTIONS TO STRATIGRAPHY

2. Quartz-phosphate sand (bed I), dark-yellowish-brown 

(10 YR 4/2), fine-grained, massive, clayey, slightly 

calcareous, poorly compacted; rests on a sharply defined, 

undulatory surface ............................. 0.00-0.10

Total thickness of the Chandler Bridge Formation. ............ 0.70-0.80

Cooper Formation, Ashley Member (Oligocene):

I. Limestone, light-olive-brown (5 Y 5/6), fine-grained, 

bioturbated, well compacted but poorly consolidated; 

contains fine-grained phosphate and quartz sand ........ 0.20-0.30

REFERENCE SECTION 2 OF THE CHANDLER BRIDGE FORMATION

[Measured 1.6 km north-northwest of junction of Ashley Phosphate Road and 

Interstate 26, 0.25 km northeast of Interstate 26 in sewerline pit at 

Northwoods Estates, in the Ladson 7 l/2-min quadrangle (northwest of 

Charleston), Charleston County, S.C. Altitude about 6 m .]

Unit Description Thickness (meters) 

Pleistocene deposits: 

6. Topsail .........................................0.15

5. Quartz sand, medium-gray (N5), medium-grained, angular,

massive, clayey, noncalcareous, well -compacted; basal quartz

and phosphate pebble bed 0.10 m thick ................... 1.65

Chandler Bridge Formation (Oligocene):

4. Quartz-phosphate sand (bed 3), medium-gray (N5), mediumgrained, massive, clayey, noncalcareous, well compacted; abundant subrounded to angular lumps of phosphate ............ .0.60

3. Quartz-phosphate silt (bed 2), medium-gray (N5), sandy

and clayey, bioturbated, noncalcareous, poorly compacted; 

sand content decreases downward so that basal 0.10 m is a sandy 

clay; abundant subrounded to angular lumps of phosphate; rests 

on a sharply defined, nearly planar surface ................ 0.30

2. Absent (bed I) ................................... .0.00

Total thickness of the Chandler Bridge Formation. ................ 0.90

Cooper Formation, Ashley Member (Oligocene):

I. Limestone, light-olive-brown (5 Y 5/6), micritic, bioturbated, well compacted but poorly consolidated; 

contains fine-grained phosphate and quartz sand ............ 0.90
ALBERT E. SANDERS AND OTHERS Hill

CONTACT RELATIONS

The basal contact of the Chandler Bridge Formation is a sharp, rolling 

(amplitude about 5 cm), sparsely burrowed surface separating sparsely 

calcareous or noncalcareous, dark-yellowish-brown (bed I) or medium-gray 

(bed 2) sand from the underlying light-olive-brown, highly calcareous sand of 

the Ashley Member of the Cooper (fig. 26, 27). This contact is interpreted 

as a disconformity. This interpretation is supported by the lack of any whale 

species (and only one genus) common to the two units, which suggests a 

significant time gap between the units.

The top of the Chandler Bridge Formation is disconformably overlain 

in all studied exposures by surficial Pleistocene deposits. This contact is 

marked by a basal Pleistocene bed of coarse-grained quartz sand containing 

many subrounded to discoidal quartz pebbles and cobbles and many rounded 

to angular phosphate pebbles, cobbles, and boulders. At some localities, the 

top of the Chandler Bridge Formation contains burrows filled with 

Pleistocene sediment and mollusk shells. Textural analysis of Chandler 

Bridge sediments from near the upper contact reveals a significant 

percentage of sand that is typical of the modal size range of the overlying 

Pleistocene sediments and that is coarser than the sand found elsewhere 

(downward) in the Chandler Bridge beds. The presence of this sand suggests 

that bioturbation of the Chandler Bridge-Pleistocene contact has taken place 

even where burrows are not readily visible near the upper contact.

Malde (1959) reported a thin sand unit similar to the Chandler Bridge 

Formation beneath the "upper Miocene Duplin marl" (equivalent to the lower 

Pliocene "Goose Creek marl" of Sloan, 1908) along the route of the F. B. 

McDowell, Jr., Tunnel in the western part of the North Charleston 7 l/2-min 

quadrangle. Because this bed is only 1.4 km northeast of a fossiliferous 

Chandler Bridge locality of comparable altitude in the eastern Ladson 7 1/2- 

min quadrangle, the unit mentioned may be assignable to the Chandler 

Bridge Formation. If so, at least locally in the North Charleston 7 l/2-min 

quadrangle, the Chandler Bridge Formation may be overlain by the "Goose 

Creek marl" of Sloan. Though not exposed, the contact between the 

Chandler Bridge Formation and the "Goose Creek marl" is presumed to be a 

disconformity.

LITHOLOGIC FEATURES

In contrast to the Pleistocene sediments, which have a median grain 

size of 2 to 2.2 0 for the quartz-sand fraction, the sediments of the 

Chandler Bridge Formation have a median grain size of 3.3 to 3.5 0 for the 

quartz-sand fraction. Generally, the phosphate-sand fraction of the 

Chandler Bridge is coarser than the quartz-sand fraction and consists of 

foraminifer internal molds and bone fragments. The quartz- and phosphatesand fractions of the Cooper Formation (Ashley Member) are similar to those 

of the Chandler Bridge. Both the upper bed and the lower bed of the 

Chandler Bridge Formation are massive and show no obvious evidence of 

bioturbation or crossbedding. In contrast, the middle bed shows extensive 

evidence of Thai I asanoides-type burrowing. The lower and middle beds are 

soft and crumble readily when dug, but the upper bed is dense and cannot be

excavated as easily. The clay content of the upper bed is not obviously 

higher than that of the other beds (table 3), so the difference in the cohesion
FIGURE 26.-Type section of the Chandler Bridge Formation showing the basal contact with the Ashley Member of 

the Cooper Formation ("zone 1," not labeled) and the three beds (beds 1-3 equivalent to "zones 2-4") composing 

the Chandler Bridge Formation. The bottom of each "zone" card marks the basal contact of the corresponding 

bed.

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of the beds is attributed here tentatively to tighter grain packing in the 

upper bed. The upper bed also differs from the lower two in that it contains 

a dominantly medium-grained phosphate-sand fraction as opposed to a 

dominantly fine-grained phosphate-sand fraction in the lower two beds.

MINERALOGY

The Chandler Bridge Formation is noncalcareous except for the basal 

bed, which is slightly calcareous. Because the basal bed is thin and directly 

overlies the highly calcareous Cooper Formation, the calcite content of the 

basal bed is possibly the result of direct reworking of Cooper sediments. The 

sand fraction of the Chandler Bridge Formation consists almost exclusively 

of quartz and phosphate but contains some very stable detrital heavy 

minerals (ilmenite and sillimanite) or their alteration products. In all beds, 

quartz predominates by weight over phosphate, but generally, within any one 

bed, phosphate is dominant in the relatively coarser fractions (except where 

weathering has selectively leached the phosphate), and quartz is dominant in 

the relatively finer fractions. The relative proportions of quartz and 

phosphate in the Chandler Bridge Formation vary widely with stratigraphic 

position; the quartz fraction ranges from 15 to 50 percent dry weight, and 

the phosphate fraction, from 5 to 35 percent. The quartz-sand fraction in 

the underlying Cooper sediments generally ranges from 10 to 25 percent.

The Chandler Bridge silt fraction also is dominated by quartz and 

phosphate, but the clay fraction consists mostly of interlayered illitesmectite having high percentages of expandable layers and small amounts of 

kaolinite and phosphate. In contrast, the clay-sized fraction of the Cooper 

sediments contains sepiolite, palygorskite, calcite, apatite, kaolinite, and 

illite-smectite. Bed I is exceptional in that it contains less kaolinite than 

either the beds above it or the Cooper below it. Clay minerals in the 

Pleistocene sediments are typically kaolinite, illite, gibbsite, and vermiculite 

(Lemon, 1979). The mineralogy of the Chandler Bridge Formation is 

summarized in table 3.

FAUNA AND FLORA

Because the Chandler Bridge Formation is thin and permeable and 

thus typically leached of carbonate, attempts to recover a calcareous 

microfauna or microflora have been either unsuccessful or equivocal in that 

the few specimens obtained may represent material reworked from the 

underlying Ashley Member of the Cooper into bed I. Unworn phosphatized 

molds of solitary corals (Balanophyllia sp.), snails, and pelecypods (some of 

the last still retaining original but decayed shell material around them) were 

found at the type section. Specimens of these three groups appear to be 

grossly similar to forms found in the Ashley Member (Druid Wilson, oral 

commun., 1970) but have not yet been studied in detail.

By far the most abundant and best preserved components of the fauna 

are vertebrates. Ray plates (Aetobatis, Myliobatis), sharks' teeth 

(Carcharpdon, Galepcerdo, Odontaspis, and others), scombroid skeletons, and 

other unidentified bony-fish remains are abundant as are skeletal remains 

representing at least four genera of sea turtles. A single femur of a 

crocodilian is the only indication thus far of these animals in the Chandler 

Bridge. Bones of birds also were recovered at the type section, but studies
ALBERT E. SANDERS AND OTHERS HII5

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of these specimens have not been completed. Among mammals, sirenian 

bones are common; some isolated elements of these animals can be referred 

to Halitherium and Metaxytherium. Whales are abundantly represented; taxa 

include at least two species of archaeocetes, four genera of squalodontoids, 

and a species of the taxonomically problematical genus Xenorophus, which is 

not the same as X. sloanii found in the underlying Ashley Member of the 

Cooper FormationTSanders, 1980).

Plant remains are also present in the Chandler Bridge Formation. At 

the type section, only remains of acritarchs were recovered from samples 

submitted for microfloral analysis (F. E. May, written commun., 1975). The 

presence of small (as much as 18 microns in diameter) sphaeromorphs and 

small (as much as 28 microns in diameter) acanthomorphs bearing very short 

(as much as 3 microns) spines was noted. The megafossil flora includes 20 to 

30 seed cases of hickory, several acorns, and a single seed of a grape (Vitis 

sp.) (J. A. Wolfe, written commun., 1971), all recovered at the type section. 

At first, we were concerned that these seed remains might have been 

introduced by Pleistocene burrowing rodents, but careful observation during 

the excavation of the type locality showed no sign of such burrowing near 

the seeds. Many acorns and hickory nuts were recovered from bed I, in 

which they were completely surrounded by normal bed I matrix; burrowing in 

this distinctively colored and textured unit would have been obvious, but no 

evidence was found of it.

ORIGIN OF THE CHANDLER BRIDGE FORMATION

The presence of a vertebrate fauna dominated by whales and, to a 

lesser extent, by sea turtles, sharks, rays, and scombroid bony fishes 

indicates that the Chandler Bridge Formation was deposited under marine to 

marginal-marine conditions. The presence of abundant hickory nuts, acorns, 

and a grape seed further restricts the likely area of deposition to nearshore 

marine or lagoonal environments. The acritarch assemblage suggests an 

inshore, basinal, turbulent environment. Thus, a back-bay to lagoonal 

environment seems best to accommodate the requirements of all the above 

faunal and floral components. The finding of many of the whale skeletons in 

nearly parallel alinement in bed 3 indicates that the whales may have 

become stranded along some sort of intertidal bar within the marginalmarine environment. The probable tighter grain packing in bed 3, mentioned 

earlier, might be explained also by accumulation along a wave-sorted 

intertidal bar.

The modal quartz-grain size found in the Chandler Bridge Formation 

(3.3 to 3.5 0) is the same as that in the quartz fraction of the underlying 

Cooper Formation. This suggests that the Chandler Bridge was derived 

either from the same source as the Cooper or by reworking of the Cooper 

from local sources. Because the Chandler Bridge is preserved only in low 

areas in the Cooper, reworking may be a more likely explanation, unless 

tectonic downwarping can be demonstrated to account for the present 

geometry and distribution of the Chandler Bridge beds. Modern rivers from 

the Piedmont carry large quantities of kaolinite and (or) its feldspar 

precursors, whereas local coastal rivers (for example, the Ashley River) do 

not. Therefore, the very low kaolinite content of bed I suggests that only a 

local coastal drainage system was present in early Chandler Bridge time.
ALBERT E. SANDERS AND OTHERS H117

AGE AND CORRELATIONS

Because the Chandler Bridge Formation lacks well-preserved 

macroinvertebrate, microfaunal, or microfloral assemblages, 

biostratigraphic correlations cannot be made. Therefore, the age of the 

Chandler Bridge must be deduced from determinations of the age of the 

immediately underlying Ashley Member of the Cooper Formation and from 

the evolutionary grades represented in the rich cetacean fauna of the 

Chandler Bridge beds. The youngest beds of the Ashley have yielded a wellpreserved planktonic foraminiferal fauna (Hazel and others, 1977; C. W. 

Poag, written commun., 1974) which includes Globigerina angulisuturalis, 

Turborotalia mendacis, and T. siakensis (all first appearing in zone P2I) as 

well as G_. gortanii and T. nana (both disappearing in P22). Thus, the Ashley 

definitely ranges into zone P21 and cannot be younger than zone P22. In the 

biostratigraphic correlation charts of Berggren (1972), Steininger and others 

(1976), and Curry and others (1978), zone P2I extends from uppermost 

Rupelian (middle Oligocene) to the middle Chattian (upper Oligocene), the 

base of this interval being marked by the appearance of G. angulisuturalis 

(Berggren, 1972). The additional presence of Globigerinoides primordius in 

the Ashley assemblage would have suggested a latest Oligocene (P22) or 

earliest Miocene (N4) age for the youngest beds of the Cooper Formation 

(Berggren, 1972), but Steininger and others (1976, p. 179) found the first 

occurrence of this species "to be worthless as an index of the 

Oligocene/Miocene boundary," noting that G_. primordius "is found in Trinidad 

and Venezuela within the Globigerinoides ciperoensis ciperoensis zone" (P22) 

and "in the western Carpathians even together with Globorotalia opima 

opima (Cicha and others, 1971)." Because the horizon of disappearance of 

G_. £. opima is currently used as the boundary between P2I and P22 

(Berggren, 1972; Steininger and others, 1976; Curry and others, 1978) and the 

because foraminifers reported from the uppermost beds of the Ashley range 

through P2I and possibly into P22, the uppermost part of the Ashley must at 

least be referable to P2I. It cannot as yet be proven to range into P22 

because the absence of G. o. opima may be an artifact of collecting or of 

paleoenvironmental conditions rather than an indication that this species was 

extinct by latest Ashley time.

The cetacean fauna of the Chandler Bridge Formation is composed of 

toothed whales (suborder Odontoceti) referable to the super-family 

Squalodontoidea Simpson, 1945, and of undescribed species of archaeocetes 

(suborder Archaeoceti). The odontocete assemblage consists of cranial 

elements and partial skeletons documenting at least five genera. Three are 

undescribed and have been designated temporarily as Genus X, Genus Y, and 

Genus Z (Whitmore and Sanders, 1976); one partial skull is tentatively 

regarded as a new species of the genus Squalodon Grateloup, 1840; and a new 

species of the genus Xenorophus Kellogg, 1923, is abundantly represented by 

cranial and postcranial elements. The type of the last genus, Xenorophus 

sloanii Kellogg (1923), was described from a partial skull found in the 

underlying Ashley Member of the Cooper Formation near Woodstock, 

Charleston County, S.C. Because of the primitive features in the holotype, 

Xenorophus was placed in the Agorophiidae by Miller (1923, p. 40). However, 

the more complete cranial material of the new species of Xenorophus has 

proved that assignment to be incorrect, and, as a result, Xenorophus was 

placed in incertae sedis by Whitmore and Sanders (1976). The other four 

genera (Squalodon, Genus X, Genus Y, Genus Z) represent the family
H118 CONTRIBUTIONS TO STRATIGRAPHY

Squalodontidae Brandt, 1873. Virtually all of the odontocete material was 

found during the Charleston Museum excavation of the Chandler Bridge beds 

conducted by Sanders (1980) during the summers of 1970-72. Supported by 

research grants from the National Geographic Society (1971-72) and the 

Charleston Scientific and Cultural Educational Fund (1970), the project 

yielded the remains of at least 17 associated partial skeletons (one from bed 

2, 16 from bed 3) within the 21- by 21-m area of excavation. Some of the 

forms represented have been discussed and figured by Whitmore and Sanders 

(1976).

Archaeocete remains were not found during the excavation at the 

type section of the Chandler Bridge Formation, but skulls and partial 

skeletons of three individuals have since been discovered in this unit at other 

localities near Charleston. One specimen was obtained from bed 3, 2.2 km 

north-northwest of the type section in 1975, and two were found in bed 2 at 

separate locations during the summer of 1978. The specimen from bed 3 has 

not been prepared and thus awaits taxonomic evaluation. Preparation of the 

two specimens from bed 2 has not been completed, but we already know that 

they represent two undescribed species that share similarities in dental 

morphology but differ in size and in details of the auditory bones. The 

relations between these two forms at the generic level and their affinities 

with other archaeocetes at the familial level are not clear at present. The 

most primitive of the three recognized suborders of the Cetacea 

(Archaeoceti, Mysticeti, Odontoceti), the Archaeoceti are best represented 

in Eocene beds and do not appear to have been validly recorded previously 

above the middle Rupelian (middle Oligocene), with the possible exception of 

Mammalodon colliveri .

As one of the largest and most diverse assemblages of cetacean 

remains yet recorded from an Oligocene formation, the Chandler Bridge 

material has furnished important new information about the telescoping of 

the cranial elements in early odontocetes (Whitmore and Sanders, 1976, 

p. 312-314) (see figs. 24-27). The degrees of telescoping (that is, the 

progressive movement of the nasal opening and contiguous bones backward 

to a position at the vertex of the skull) represented in the three new

 ^The archaeocete Phococetus vasconum (Delfortrie) was described 

from a single tooth from beds in France that were thought to be of 

Burdigalian (early Miocene) Age (Kellogg, 1936, p. 230, citing Dollfus, 1909, 

p. 385, 397) but which have since been referred to the middle Rupelian 

(middle Oligocene) (Richard, 1946, p. 136, 342). Kekenodon onamata Hector, 

from New Zealand, was originally reported from the Eocene (Hector, 1881) 

and was later referred to the early Miocene (Kellogg, 1936) but has since 

been placed in the middle Oligocene (Keyes, 1973). Chonecetus sookensis 

Russell, from the Sooke Formation (upper Oligocene) of Vancouver Island, 

British Columbia, was originally described as an archaeocete (Russell, 1968), 

but the propriety of this assignment has been questioned by Mitchell 

(Whitmore and Sanders, 1976, p. 305) and by Barnes (1976, p. 324). 

Aetiocetus cotylalveus Emlong (1966), from the Yaquina Formation (upper 

Oligocene part) of Oregon, Ferecetotherium kellogg[ Mchedlidze (1970), 

from upper Oligocene beds in the Caucasus region of the Soviet Union, and 

Mirocetus riabinini Mchedlidze (1970), from upper Oligocene beds of 

Azerbaijan, were originally described as archaeocetes but were referred to 

incertae sedis by Whitmore and Sanders (1976, p. 305, 317).
ALBERT E. SANDERS AND OTHERS H119

squalodontids (Genus X, Genus Y, Genus Z) from the Chandler Bridge 

Formation compare most closely with those of squalodontids from the 

Chattian (upper Oligocene) of Europe (Whitmore and Sanders, 1976; Sanders, 

1980).

Genus X represents the same stage of telescoping as that of 

Eosquglodon Igngewieschei Rothausen (I968a) (Whitmore and Sanders, 1976, 

figs. 2b, 5; Sanders, TWO) from Eochattian beds at Doberg bei Bunde 

(Westfalen) in northwestern Germany (Karlheinz Rothausen, written 

commun., 1979). The Eochattian sands (Chattian A) at Doberg have been 

referred to nannoplankton zone NP24 (Martini and Muller, 1975) and are 

considered to be of early Chattian Age (Curry and others, 1978, p. 46). The 

genus is also represented by E. latirostris (Capellini, 1904) (Rothausen, 

I968b) from the "arenaria calcarifera" (Capellini, 1904, p. 441) at Schio, 

northern Italy. Formerly considered to be of Miocene age (Capellini, 1904), 

these deposits since have been placed in the late Oligocene (Rothausen, 

I968b, p. 4). Genus X is a smaller form than either of these two species and 

differs also in having teeth that are similar to those of taxa assigned to the 

genus Microcetus, the type-genus of which, M. ambiguus (Meyer, 1840), was 

founded only upon a series of teeth from Doberg (Rothausen, 1961). AA. 

sharkovi Dubrovo and Sharkov (1971), a small squalodontid that also has M. 

ambiguus-like teeth, was described from a partial skull and two mandibles 

from upper Oligocene deposits on the Magyshlak Peninsula in western 

Kazakhstan, U.S.S.R. (Dubrovo and Sharkov, 1971). Because the species 

represented by Genus X is clearly not referable to M. sharkovi, and because 

there is no cranial material for the holotype of Microcetus ambiguus, Genus 

X cannot be safely assigned to Microcetus.

As noted by Sanders (1980), the stage of telescoping exemplified by 

Eosqualodon and Genus X is represented also in the holotype of Agriocetus 

incertus (Brandt, 1874), a poorly preserved partial skull from the Linz Sands 

at Linz, Austria. These sands have been referred to nannoplankton zone 

NP25 (uppermost Oligocene) by Rabeder and Steininger (1975, p. 177). 

Sulakocetus dagestanicus Mchedlidze (1976), from upper Oligocene deposits 

in the northern Caucasus region of the U.S.S.R. (Mchedlidze, 1976, p. 42, fig. 

12), and "Prosqualodon" ham i I ton i Benham (1937, figs. 1-3), from upper 

Oligocene beds mNew Zealand, represent grades of this stage of 

telescoping, as suggested by Rothausen (1970, p. 186). "P." ham i I ton! is not a 

valid member of the genus Prosqualodon and needs to be reassigned.

Genus Y from the Chandler Bridge Formation demonstrates a more 

primitive stage of telescoping in which there is a pronounced intertemporal 

constriction (Whitmore and Sanders, 1976, fig. 4), a characteristic feature in 

early odontocetes in which the parietals form a part of the skull roof. 

During later stages of telescoping, these bones were eliminated gradually 

from the skull roof, apparently through atrophy, and are restricted to the 

sides of the skull in odontocetes of Miocene to Holocene time. Among the 

extinct odontocetes described to date, Genus Y can be compared only with 

the squalodont Patriocetus ehrlichi (van Beneden, 1865; Rothausen, I968a, 

fig. 2a) from the Linz Sands, notecT earlier as being of latest Oligocene age 

(Rabeder and Steininger, 1975). Although these two forms have many 

differences, they appear to represent the same general stage of telescoping, 

to which Rothausen (I968a, p. 87) has applied the term "protosqualodontid," 

in reference to the evolutionary level reflected in the cranial morphology of
H120 CONTRIBUTIONS TO STRATIGRAPHY

Patriocetus. Rothausen (1970, p. 180) suggested that Patriocetus was a 

survivor "of an evolutionary level that was more usual in earlier times, 

maybe in the middle Oligocene."

Genus Z, from bed 2 of the Chandler Bridge Formation, documents a 

stage of telescoping that is morphologically intermediate between Genus X 

and Genus Y in some respects but is closer to Genus Y in others. The 

combination of features in the skull of this form is not duplicated in any 

squalodont described to date, but the effects of the intertemporal 

constriction upon the adjacent bones are the same as those in Genus Y 

(Whitmore and Sanders, 1976, p. 312; Sanders, I960).

By far the most primitive of the odontocetes of the Chandler Bridge 

Formation, the new species of Xenorophus has the most archaic braincase 

structure yet recorded in the Odontoceti (Whitmore and Sanders, 1976, fig. 

la). Although telescoping of the rostral elements is well advanced, the 

relative positions of the bones of the braincase are essentially the same as 

those in typical land mammals, quite unlike the radically restructured 

braincase in the toothed whales of Miocene to Holocene time.

The significance of the degrees of telescoping manifested in the 

Chandler Bridge cetaceans is that this process is complete in all known 

odontocetes from the lower Miocene. As summarized by Rothausen (1970, 

p. 187-188):

"the last distinct [evolutionary] advance is that between the 

Chattian and the Aquitanian. But the main steps of evolution in the 

squalodontoidea had already occurred within the Oligocene. In the 

Chattian there are very clear trends toward Neogene faunal assemblages of the Squalodontoidea. With the Aquitanian [early Miocene] 

had disappeared also the survivors of various earlier stages of 

evolution that had still been in existence in both hemispheres during 

the Chattian."

Although a few as-yet-undiscovered forms having incomplete telescoping 

may have straggled into the earliest Miocene, the early Miocene odontocetes 

Squalodon (S_. catulli, S_. bellunense), Prosqualodon (P. austral is), 

Neosqualodon, Phoberodon, Diochoticus, Acrodelphis, Argyrocetus, 

Cyrtodelphis, Eurhinodelphis, and Diaphorocetus all possessed fully 

telescoped crania and together serve to demonstrate that this stage of 

telescoping was fully established in the odontocetes from the lower Miocene 

(Kellogg, 1928, p. 62).

The primitive aspects of the Chandler Bridge cetacean fauna seem, 

therefore, to provide an adequate indication of the age of this formation. 

Telescoping of the cranial elements is incomplete (that is, the parietals are 

still in place in the skull roof) in three of the four squalodont genera 

represented (Genus X, Genus Y, Genus Z) and has not taken place at all in 

the braincase of Xenorophus. Thus, telescoping is incomplete in four (80 

percent) of the five odontocete genera recorded from the type locality, the 

lone example of completed telescoping being the partial skull tentatively 

referred to the genus Squalodon. In contrast to this record of a single 

individual having completed telescoping, Xenorophus is represented by the 

remains of at least 10 animals, Genus X, by at least 8, and Genus Y, by 4 

specimens, one of which is a virtually complete skeleton. Genus Z is known 

from one individual. When the three archaeocete specimens from the
ALBERT E. SANDERS AND OTHERS H121

Chandler Bridge beds are added, the primitive composition of this 

assemblage becomes even more apparent. The evolutionary levels 

represented therein are uncharacteristic of Miocene faunas known from 

elsewhere and correspond much more closely to those of forms from the 

upper Oligocene of Europe. On these grounds, and in the absence of 

evidence to the contrary, it seems safe to conclude that the Chandler Bridge 

Formation is of Chattian (late Oligocene) Age.

Huddlestun (1973) alluded to the presence of an upper (?) Oligocene 

unit and a lower Miocene unit in the vicinity of the lower Savannah River, 

Ga. The older ("Alum Bluff") unit belongs in P22 or N4, whereas the younger 

("lower Marks Head marl") unit belongs in N4 or N5 (J. E. Hazel written 

commun., 1979). The older of these units might be, but probably is not, time 

correlative with the Chandler Bridge Formation; biostratigraphic data are 

too few for us to make a determination. Other than Huddlestun's older unit, 

no possible correlatives to the Chandler Bridge Formation have been 

reported in the Atlantic Coastal Plain.

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assemblages: Systematic Zoology, v. 25, p. 321-343, figs. 1-3.

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parts of the skeleton of Prosqualodon hamiltoni n. sp.: Royal Society 

of New Zealand Transactions, v. 67, p. 8-14, 4 pis.

Berggren, W. A., 1972, A Cenozoic time scale Some implications for 

regional geology and paleobiogeography: Lethaia, v. 5, no. 2, 

p. 195-215.

Brandt, J. F. von, 1874, Erganzungen zu den fossilen Cetaceen Europe's: 

Academy of Science of Petersburg, v. 16, 84 p., 3 pis.

Capellini, Giovanni, 1904, Avanzi di squalodonte nella arenaria di Grumi dei 

Frati presso schio: Accademia delle Scienze dell'lnstituto di Bologna 

Memorie, v. 10, p. 437-445, I fig.

Cicha, Ivan, Hagn, Herbert, and Martini, Erlend, 1971, Das Oligozan und 

Miozan der Alpen und der Karpaten; Ein Vergleich mit Hilfe 

planktonischer Organismen: Bayerische Staatssammlung 

Palaeontologie und Historiche Geologic Mitteilungen, v. 11, p. 279-293.

Curry, Dennis, Adams, C. G., Boulter, M. C., Dilley, F. C., Eames, F. E., 

Funnell, B. M., and Wells, M. K., 1978, A correlation of Tertiary rocks 

in the British Isles: Geological Society of London Special Report 12, 

72 p., 5 figs.

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Geologique Bulletin, v. 19, no. 124, p. 379-508.

Dubrovo, I. A., and Sharkov, A. A., 1971, Kit iz verkhnyego oligotsena 

Mangyshlaka: Akademiya Nauk SSSR Doklady, v. 198, no. 6, p. 1403- 

1406.
H122 CONTRIBUTIONS TO STRATIGRAPHY

Emlong, D. R., 1966, A new archaic cetacean from the Oligocene of 

northwest Oregon: Oregon University Museum of Natural History 

Bulletin 3, 51 p., 15 figs.

Goddard, E. N., and others, 1948, Rock-color chart: Washington, D.C., 

National Research Council, 6 p. (Republished by Geological Society of 

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E., McLean, D. M., Poore, R. Z., Smith, C. C., Sohl, N. F., Valentine, P. 

C., and Witmer, R. J., 1977, Biostratigraphy of the deep corehole 

(Clubhouse Crossroads corehole I) near Charleston, South Carolina: 

U.S. Geological Survey Professional Paper 1028-F, p. 71-89.

Hector, James, 1881, Notes on New Zealand Cetacea, Recent and fossil 

[abs.j: New Zealand Institute Transactions, v. 13, p. 434-436.

Huddlestun, Paul, 1973, Lower Miocene biostratigraphy along the Savannah 

River, Georgia: Gulf Coast Association of Geological Societies 

Transactions, v. 23, p. 432-433.

Kellogg, Remington, 1923, Description of an apparently new toothed 

cetacean from South Carolina: Smithsonian Miscellaneous Collections, 

v. 76, no. 7, p. 1-7, pis. 1-2.

___1928, The history of whales Their adaptation to life in the water: 

Quarterly Review of Biology, v. 3, no. I, p. 29-76 and 174-208, 11 figs.

___1936, A review of the Archaeoceti: Carnegie Institution of Washington 

Publication 482, v. 15, 366 p.

Keyes, I. W., 1973, Early Oligocene squalodont cetacean from Oamaru, New 

Zealand: New Zealand Journal of Marine and Freshwater Research, v. 

7, no. 4, p. 381-390, 6 figs.

Lemon, E. M., Jr., 1979, Textural and clay-mineral differentiation of 

Oligocene and Pleistocene deposits in the Stallsville quadrangle, South 

Carolina [abs.]: Geological Society of America Abstracts with 

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Malde, H. E., 1959, Geology of the Charleston phosphate area, South 

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Martini, Erlend, and Muller, C., 1975, Calcareous nannoplankton from the 

type Chattian: Congress on Neogene Mediterranean Stratigraphy, 6th, 

Bratislava, Yugoslavia, Proceedings, 1975, v. I, p. 37-41.

Mchedlidze, G. A., 1970, Nekotorye obshchie cherti istorii kitoobraznykh, 

Ch. I: Akademiia Nauk Gruzinskoy SSR, Institut Paleobiologii 

"Metsniereba" Press, 112 p., 23 figs., 6 pis.

___1976, Osnovniye cherti paleobiologicheskoi istorii kitoobraznich: 

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ALBERT E. SANDERS AND OTHERS H123

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Tertiarmergel: Beitrage zur Petrefactenk, v. 3, p. 3-11, pi. 8, fig. I.

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korrelationsmoglichkeiten von Saugetierfaunen aus dem Oligo/Miozan 

der Zentralen Paratethys: Congress on Neogene Mediterranean 

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177-183.

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Abhandlungen, v. 112, p. 106-118, pi. 23.

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83-103, 3 figs., 2 pis.

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Memorie, v. 26, 19 p., I fig., 2 pis.

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Vancouver Island, British Columbia: Canadian Journal of Earth 

Sciences, v. 5, no. 4, pt. I, p. 929-933, 2 pis.

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Charleston, South Carolina: National Geographic Society Research 

Report, v. 12, p. 601-621.

Sanders, A. E., Lemon, E. M., Jr., and Weems, R. E., 1979, A newly 

recognized post-Cooper/pre-Hawthorn stratigraphic unit in the lower 

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H124 CONTRIBUTIONS TO STRATIGRAPHY

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d'Anvers, les squalodons: Acade'mie Royale de Belgique Memoires, 

Classe des Sciences, v. 35, 85 p.

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formations of South Carolina: South Carolina Division of Geology 

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CONTRIBUTIONS TO STRATIGRAPHY H125

NEW MEMBERS OF THE MADISON LIMESTONE

(DEVONIAN AND MISSISSIPPIAN), 

NORTH-CENTRAL WYOMING AND SOUTHERN MONTANA

By William J. Sando 

INTRODUCTION

The stratigraphy of the Madison Limestone in the mountain ranges of 

north-central Wyoming and southern Montana was studied by the author 

during the summers of 1964, 1965, 1966, 1968, and 1970. Three formal 

members and three informal members of the Madison were described in a 

series of reports on the stratigraphy of the area (Sandberg and Klapper, 

1967; Sando, 1967, 1968, 1972, 1974, 1975, 1976, 1977, 1979). The purpose of 

this report is to propose formal nomenclature for the three previously 

informal members of the Madison.

Complete sequences of the members of the Madison are recognized in 

the Beartooth Mountains, Absaroka Range, Washakie Range, Gros Ventre 

Range, Wind River Range, Owl Creek Mountains, and Bighorn Mountains 

(fig. 28). Some of the members extend to outcrop areas to the north and 

southeast of the area of this study. Preliminary examination of well logs 

suggests that the members are recognizable also in the subsurface of the 

Bighorn, Wind River, and Powder River Basins.

Stratigraphic sections measured in the Bighorn Mountains provide 

complete sequences of the Madison that show variations in thickness and 

lithology characteristic of its members. The best reference section for the 

Madison in north-central Wyoming and southern Montana is the well-exposed 

and readily accessible Little Tongue River section described by Sando (1976, 

p. 48-52) along U.S. Highway 14 above the Little Tongue River west of 

Dayton, Wyo. (fig. 28). This section also serves as the type section for the 

three new members proposed here.

STRATIGRAPHY

Previously recognized members of the Madison Limestone in northcentral Wyoming and southern Montana are, in ascending order, the 

Cottonwood Canyon Member (Sandberg and Klapper, 1967), the lower 

dolomite member (Sando, 1972), the Woodhurst Member (Weed, I899a, b), the 

cherty dolomite member (Sando, 1972), the cliffy limestone member (Sando, 

1972), and the Bull Ridge Member (Sando, 1968). The revised nomenclature 

is compared with previous nomenclature on figure 29.

Little Bighorn Member (new name)

The lower dolomite member of Sando (1972) is here formally named 

Little Bighorn Member for exposures in Little Bighorn Canyon in NW 1/4 sec. 

30, T. 58 N., R. 89 W., Sheridan County, Wyo. (see Sando, 1976, pi. I, for 

graphic section). The type section is the Little Tongue River section of 

Sando (1976, p. 48-52) in NEI/4 sec. 27, T. 57 N., R. 87 W.,

U.S. Geol. Survey Bull. 1529-H, 1982, p. HI25-HI30
HI26 CONTRIBUTIONS TO STRATIGRAPHY

110°

45°| 

0 50 MILES

I I I I I I

I i I I i I

0 50 KILOMETERS

.I_______L.

FIGURE 28.-Mountain ranges and basins of north-central Wyoming and southern Montana where new members of the Madison Limestone are recognized and location of type 

section.
WILLIAM J. SANDO HI27

c

CD 

O

U.

CD

Jmeston

 *

c 

o

CO

T3

CD

Jg

Members

Sando (1972, 1975, 

1976, 1977, 1979)

Bull Ridge

Member

Upper solution zone

Cliffy

limestone

member

Lower solution zone

Cherty 

dolomite 

member

Woodhurst

Member

Lower dolomite 

member

Cotton wood Canyon Member

This report

Bull Ridge

Member

Upper solution zone

Little

Tongue

Member

Lower solution zone

Big Goose 

Member

Woodhurst

Member'

Little Bighorn 

Member

Cottonwood Canyon Member

'> * 

2 w

a.

u

CD

E c

CD _CO CD ~

5

C 

CD 

-CD 

O)

CD

CO

o

-«

Kinder- hookian

E.<"

0

 -z

HI Tf. "^

fcsat

NVIddlS

in in

5

QC

1

DEVONIAN

FIGURE 29. -Stratigraphic diagram comparing new nomenclature of Madison Limestone 

in north-central Wyoming and southern Montana with previous nomenclature and 

showing ages of the members.
H128 CONTRIBUTIONS TO STRATIGRAPHY

Sheridan County, Wyo. The member includes units 5 and 6 of Sando's (1976, 

p. 51) section description and is 17.5 m thick in the type section.

The Little Bighorn Member rests conformably on the Cottonwood 

Canyon Member at most localities but is regionally unconformable on the 

Jefferson Dolomite (Devonian), Bighorn Dolomite (Ordovician), or Gallatin 

Limestone (Cambrian and Ordovician) where the Cottonwood Canyon 

Member is absent. The Little Bighorn Member is overlain conformably by 

the Woodhurst Member of the Madison. The member consists of 3 to 48 m of 

thick-bedded, fine- to medium-crystalline, crinoidal dolomite and dolomitic 

limestone. Conodonts recovered at a few localities date the member as 

Kinderhookian in age. Brachiopods and corals also occur rarely in the 

member.

Big Goose Member (new name)

The cherty dolomite member of Sando (1972) is here formally named 

Big Goose Member for exposures on Big Goose Creek in NW 1/4 sec. 2, 

T. 54 N., R. 86 W., Sheridan County, Wyo. (see Sando, 1976, pi. I, for graphic 

section). The type section is the Little Tongue River section of Sando (1976, 

p. 48-52) in NE 1/4 sec. 27, T. 56 N., R. 87 W., Sheridan County, Wyo. The 

member includes units 19 through 24 of Sando's (1976, p. 50) section 

description and is 55.5 m thick in the type section.

The Big Goose Member rests conformably on the Woodhurst Member 

and is overlain conformably by the Little Tongue Member. The Big Goose 

consists of 38 to 100 m of predominantly fine-grained, thin- to mediumbedded, very cherty dolomite and dolomitic limestone. The member contains 

rare limestone beds at some localities. Autobrecciation and shattering of 

the rock are distinctive features. The few corals and brachiopods found in 

the member support an Osagean age assignment determined mainly on the 

occurrence of the member between members dated as Osagean on the basis 

of foraminifers.

Little Tongue Member (new name)

The cliffy limestone member of Sando (1972) is here formally named 

Little Tongue Member for exposure at Little Tongue River in NW 1/4 

sec. 26, T. 56 N., R. 87 W., Sheridan County, Wyo. (see Sando, 1976, pi. I, for 

graphic section). The type section is the Little Tongue River section of 

Sando (1976, p. 48-52) at the same locality. The member includes units 25 

through 29 of Sando's (1976, p. 50) section description and is 66.9 m thick in 

the type section.

The Little Tongue Member rests conformably on the Big Goose 

Member and is overlain either conformably by the Bull Ridge Member or 

disconformably by the Amsden Formation where the Bull Ridge Member was 

removed by post-Madison, pre-Amsden erosion. The Little Tongue Member 

consists mostly of cliff-forming medium- to thick-bedded, cherty, crinoidal 

limestone and dolomitic limestone, but at some localities the member is 

predominantly or entirely crinoidal dolomitic limestone and dolomite. At 

most localities, the base of the member is marked by a solution breccia 

(lower solution zone of Sando, 1972) 2 to 13m thick that represents a 

leached interval of evaporite, carbonate, and terrigenous rocks; anhydrite
WILLIAM J. SANDO HI29

occurs at this level at some subsurface localities. The limestone beds 

immediately above the solution zone are ordinarily brecciated because of 

foundering of the roof of the solution zone, forming a collapse zone 5 to 24 

m thick. The Big Goose Member ranges in thickness from 24 to 87 m. Large 

spiriferoid brachiopods and corals are common to abundant in the limestone 

beds. Foraminifers of Mamet Zone 9 are common and indicate a late 

Osagean age for the member; Zone 10 foraminifers also are present at one 

locality.

REFERENCES CITED

Sandberg, C. A., and Klapper, Gilbert, 1967, Stratigraphy, age, and 

paleotectonic significance of the Cottonwood Canyon Member of the 

Madison Limestone in Wyoming and Montana: U.S. Geological Survey 

Bulletin I25I-B, p. BI-B70, 5 figs.

Sando, W. J., 1967, Madison Limestone (Mississippian), Wind River, Washakie, 

and Owl Creek Mountains, Wyoming: American Association of 

Petroleum Geologists Bulletin, v. 51, no. 4, p. 529-557, 8 figs.

___1968, A new member of the Madison Limestone (Mississippian) in 

Wyoming: Geological Society of America Bulletin, v. 79, no. 12, 

p. 1855-1858, 2 figs.

___1972, Madison Group (Mississippian) and Amsden Formation 

(Mississippian and Pennsylvanian) in the Beartooth Mountains, northern 

Wyoming and southern Montana: Montana Geological Society, 21st 

Annual Field Conference Guidebook, p. 57-63, 9 figs., I pi.

___1974, Ancient solution phenomena in the Madison Limestone 

(Mississippian) of north-central Wyoming: U.S. Geological Survey 

Journal of Research, v. 2, no. 2, p. 133-141, 3 figs.

___1975, Stratigraphic sections of the Madison Limestone and Amsden 

Formation, west flank of the Bighorn basin, Wyoming: Wyoming 

Geological Association, 27th Annual Field Conference Guidebook, 

p. 129-137, 7 figs.

___!976, Madison Limestone (Devonian and Mississippian), east flank of 

Bighorn Mountains: Wyoming Geological Association, 28th Annual 

Field Conference Guidebook, p. 45-52, 2 figs., I pi.

_____\ 977, Stratigraphy of the Madison Group (Mississippian) in the northern 

part of the Wyoming-Idaho overthrust belt and adjacent areas: 

Wyoming Geological Association, 29th Annual Field Conference 

Guidebook, p. 173-177, I fig., I pi.

___1979 [l980j, Lower part of the Carboniferous, m_ Lageson, D. R., 

Maughan, E. K., and Sando, W. J., The Mississippian and Pennsylvanian 

(Carboniferous) Systems in the United States Wyoming: U.S. 

Geological Survey Professional Paper I I 10-U, 38 p., 12 figs.
H130 CONTRIBUTIONS TO STRATIGRAPHY

Weed, W. H., I899a, Fort Benton Folio, Montana: U.S. Geological Survey 

Geologic Atlas, Folio 55, 7 p., maps.

J899b, Little Belt Mountains Folio, Montana: U.S. Geological Survey

Geologic Atlas, Folio 56, 9 p., maps.
CONTRIBUTIONS TO STRATIGRAPHY HI 3 I

HUNTERSVILLE CHERT (DEVONIAN) EXTENDING FROM

SOUTHWESTERN VIRGINIA INTO SOUTHWESTERN NEW YORK,

AND ITS BOBS RIDGE SANDSTONE MEMBER

By E. G. A. Weed

The Huntersville Chert is a discrete mappable lithologic unit, 

extensive in outcrop and in the subsurface (fig. 30), and mappable at 

1:24,000. The name was introduced by Price (1929) of the West Virginia 

Geological Survey and has been used in their published reports during the 

past 50 years. This paper recommends that Huntersville Chert be accepted 

as a valid geologic name for use by the U.S. Geological Survey.

The name Huntersville was first applied by Price (1929, p. 236-239) to 

a yellow to dark-gray sandy chert, which contains a sparse marine fauna of 

Early Devonian age. Price (1929, p. 397-398) also described an almost white, 

fine-grained sandstone unit commonly iron stained in outcrop at the top of 

the Huntersville.

The Huntersville Chert crops out along the Allegheny Front in parts 

of Virginia and West Virginia. The type locality is in the vicinity of 

Huntersville in southeastern Pocahontas County, W. Va. (Price, 1929). Its 

geographic extent in the subsurface is from southwestern Virginia, northward 

through West Virginia, Kentucky, Ohio, Maryland, and Pennsylvania, to 

extreme southwestern New York State (Oliver and others, 1971). It ranges in 

thickness from 5 to more than 60 m in northern West Virginia. An arbitrary 

limit at less than 50 percent chert is used to define the separation of 

Huntersville Chert from its neighboring units. The Huntersville Chert is best 

developed in northeastern West Virginia and southern Pennsylvania. It 

overlies the Oriskany Sandstone and underlies the Marcellus Shale. Where 

present, the Tioga Ash Bed lies at or near the base of the Marcellus Shale 

and above the Huntersville Chert.

Woodward (1943) described the gradational relation between the 

Huntersville Chert and the Needmore Shale to the east.

Dennison (1961) placed the Huntersville in the Onesquethawan Stage 

(Lower and Middle Devonian) in Virginia and West Virginia. It intertongues 

with the Onondaga Limestone and the Needmore Shale to the northeast and 

east. It intergrades with the Columbus Limestone to the west and northwest 

in Ohio, and along the south shore of Lake Erie the Huntersville merges into 

the cherty limestone of the Bois Blanc Formation (Dennison, I960).

Dennison (1961, p. 25-33) presented a detailed description of the 

subsurface Huntersville Chert. All gradations between chert and shale exist 

in the eastern part of the Huntersville. In the central part of the 

Huntersville, the chert is nearly free of carbonate. To the west, the chert 

becomes more calcareous and dolomitic. The chert has a higher clastic 

content in the south.

U.S. Geol. Survey Bull. 1529-H, 1982, p. HI3I-HI33
HI 32 CONTRIBUTIONS TO STRATIGRAPHY

78°

FIGURE 30.-Main subsurface extent of the Huntersville 

Chert, southwestern Virginia to southwestern Pennsylvania (modified from Oliver and others, 1971).
E.G. A. WEED HI33

Dennison also named Price's sandstone member in the upper part of 

the Huntersville Chert, calling it the Bobs Ridge Sandstone Member of the 

Huntersville Chert (1961, p. 33-35). Dennison's Bobs Ridge is also herein 

accepted as a valid geologic name for U.S. Geological Survey usage in West 

Virginia and Virginia. Its type locality is Bobs Ridge in Greenbrier County, 

W. Va., and it crops out along Browns Mountain anticline. The member is 

fine-grained quartz sandstone with much "glauconite." It is 2 to 3 m in 

thickness at the type locality and underlies the Tioga Ash Bed of the 

Marcellus except where a tongue of the Needmore Shale is interposed.

Oliver and others (1967, p. 1018-1019) discussed the relative position 

of the Huntersville in the Onesquethawan Stage and showed its extent in the 

subsurface and its relation to the Bois Blanc Formation, the Columbus 

Limestone, the Needmore Shale, and the Onondaga Limestone (Oliver and 

others, 1969).

REFERENCES CITED

Dennison, J. M., 1960, Stratigraphy of Devonian Onesquethaw Stage in West 

Virginia, Virginia, and Maryland: Dissertation Abstracts, v. 21, no. 3, 

p. 593; University of Wisconsin, unpub. dissertation, 339 p.

___1961, Stratigraphy of Onesquethaw Stage of Devonian in West Virginia 

and bordering States: West Virginia Geological Survey Bulletin 22, 

87 p.

Oliver, W. A., Jr., de Witt, Wallace, Jr., Dennison, J. M., Hoskins, D. M., and 

Huddle, J. W., 1967, Devonian of the Appalachian basin, United States, 

_m International Symposium on the Devonian System: Alberta Society 

of Petroleum Geologists, Calgary, Alberta, Canada, v. I, p. 1001-1040.

___1969, Correlation of Devonian rock units in the Appalachian basin: 

U.S. Geological Survey Oil and Gas Investigations Chart OC-64.

___1971, Isopach and lithofacies maps of the Devonian in the Appalachian 

basin: Pennsylvania Bureau of Topographic and Geologic Survey, 

Progress Report 182, [map] sheet 4.

Price, P. H., 1929, Pocahontas County: West Virginia Geological Survey 

County Report, 531 p.

Woodward, H. P., 1943, Silurian system of West Virginia: West Virginia 

Geological Survey, v. 15, 655 p.

CONTRIBUTIONS TO STRATIGRAPHY H135

NEALMONT LIMESTONE (MIDDLE ORDOVICIAN) EXTENDING FROM

SOUTHWESTERN VIRGINIA INTO SOUTHWESTERN NEW YORK

IN THE CENTRAL APPALACHIANS

By E. G. A. Weed

The Nealmont Limestone is a discrete lithologic unit, mappable at 

1:24,000, and extensive in outcrop and in the subsurface in Pennsylvania,

West Virginia, and Virginia. Kay introduced the Nealmont in an abstract in 

1941 and formally defined it in 1944. The name has been used in many

published reports during the past 40 years. This paper recommends that

Nealmont Limestone be accepted as a valid geologic name for use by the

U.S. Geological Survey.

The name Nealmont was first applied by Kay (1941) to a limestone in 

the Trenton Group of Middle Ordovician age, including as members the type 

Rodman, Lemont, and Centre Hall. It ranges in thickness from 20 to 40 m. 

Kay (1943) included the Nealmont in his discussion of limestone resources in 

central Pennsylvania.

The Nealmont type section at Union Furnace, Huntingdon County, 

Pa., is 40 m in thickness (Kay, 1944). It is underlain by rocks of the Black 

River Group or Limestone and overlain by Kay's Salona Limestone. In 

descending order, Kay's (1944) Nealmont includes the Rodman, Centre Hall, 

and Oak Hall Members. Kay described the Rodman Member as dark impure 

fossiliferous limestone, the Centre Hall Member as gray shaly limestone, and 

the Oak Hall Member as gray fossiliferous limestone of medium texture with 

interbedded coquinal ledges. Perry (1964) identified the Nealmont in the 

Ray Sponaugle well, Pendleton County, W. Va., and described it (1972) as 

about 85 m of predominantly thin wavy-bedded fine-grained limestone with 

clay partings overlain and underlain by beds similar to those in the type 

area. Kay's Oak Hall Member, the basal member, included two beds of 

altered volcanic ash (Kay, 1956). Equivalent ash beds are present in the 

Nealmont in West Virginia (Kay, 1956; Perry, 1964, 1972). Knowles (1966) 

described the Nealmont at Ashcom, Pa., as a dark-gray platy thick-bedded 

(up to 15 cm) limestone containing many bioclastic beds.

Some of the volcanic ash beds, also termed K-bentonite or 

metabentonite, present in the Middle Ordovician (Kay, 1944; Craig, 1949; 

Perry, 1964; Wagner, 1966) have been shown to be correlative throughout the 

Appalachian basin, especially the two lower beds of Kay's Oak Hall Member.

Cooper and Cooper (1946) and Pierce (1966) discuss the occurrence of 

the partly equivalent Edinburg Formation and Chambersburg Limestone in 

Virginia and Pennsylvania.

The Nealmont, striking northeast-southwest, crops out in the western 

anticlines of the Appalachians in Pennsylvania, West Virginia, and Virginia 

(Kay, 1944; Cardwell and others, 1968; Perry, 1972). It merges eastward into 

the Mercersburg Formation of Kay (1944) and Craig (1949) and extends 

southwestward into West Virginia and Virginia (Kay, 1956), where it becomes 

increasingly argillaceous and grades into the reddish Moccasin Formation in

U.S. Geol. Survey Bull. 1529-H, 1982, p. HI35-H136
HI 36 E. G. A. WEED

Bath County (Bick, 1962). The Nealmont is recognized in outcrops in central 

Pennsylvania east of the Allegheny Front. Wagner (1966, pi. 7) shows it 

extending westward in the subsurface into the Pittsburgh-Huntington basin. 

Northwestward, the Nealmont grades into the Verulam Formation in Ontario 

(Wagner, 1966). To the north, in New York, the upper part of the Nealmont 

appears to be equivalent to the Kirkfield of Ontario (Wagner, 1966).

REFERENCES CITED

Bick, K. F., 1962, Geology of the Williamsville quadrangle, Virginia: Virginia 

Division of Mineral Resources Report of Investigations 2, 40 p.

Cardwell, D. H., Erwin, R. B., and Woodward, H. P., 1968, Geologic map of 

West Virginia: West Virginia Geological Survey, 2 sheets.

Cooper, B. N., and Cooper, G. A., 1946, Lower Middle Ordovician 

stratigraphy of the Shenandoah Valley, Virginia: Geological Society of 

America Bulletin, v. 57, p. 35-1 14.

Craig, L. C., 1949, Lower Middle Ordovician of south-central Pennsylvania: 

Geological Society of America Bulletin, v. 60, p. 707-799.

Kay, Marshall, 1941, Middle Ordovician formations in central Pennsylvania 

[abs.]: Geological Society of America Bulletin, v. 52, no. 12, p. 1969.

___1943, Chemical lime in central Pennsylvania: Economic Geology, v. 38, 

no. 3, p. 188-203.

___1944, Middle Ordovocian of central Pennsylvania: Journal of Geology, 

v. 52, no. I, p. 1-24,97-116.

___1956, Ordovician limestones in the western anticlines of the 

Appalachians in West Virginia and Virginia northeast of the New 

River: Geological Society of America Bulletin, v. 67, no. I, p. 55-106.

Knowles, R. R., 1966, Geology of a portion of the Everett 15-minute 

quadrangle, Bedford County, Pennsylvania: Pennsylvania Topographic 

and Geological Survey Progress Report 170, 90 p.

Perry, W. J., Jr., 1964, Geology of the Ray Sponaugle well, Pendleton 

County, West Virginia: American Association of Petroleum Geologists 

Bulletin, v. 48, no. 5, p. 659-669.

___1972, The Trenton Group of Nittany anticlinorium, eastern West 

Virginia: West Virginia Geologic and Economic Survey Circular 13, 

30 p.

Pierce, K. L., 1966, Bedrock and surficial geology of the McConnellsburg 

quadrangle, Pennsylvania: Pennsylvania Geological Survey, 4th ser., 

Atlas I09a, 11 I p.

Wagner, W. R., 1966, Stratigraphy of the Cambrian to Middle Ordovician 

rocks of central and western Pennsylvania: Pennsylvania Geological 

Survey, 4th ser., Bulletin G49, 156 p.
CONTRIBUTIONS TO STRATIGRAPHY H137

RECOGNITION AND FORMALIZATION OF THE PLIOCENE "GOOSE 

CREEK PHASE" IN THE CHARLESTON, SOUTH CAROLINA, AREA

By Robert E. Weems, Earl M. Lemon, Jr., Lucy McCartan, 

Laurel M. Bybell, and Albert E. Sanders

ABSTRACT

Although never formally introduced into U.S. Geological Survey 

usage, Earle Sloan's (1908) "Goose Creek phase" of the Charleston, S.C., area 

has proven to be a valid and properly defined stratigraphic unit. As such, it 

is revived herein and formally recognized as the Goose Creek Limestone. 

The age of this unit is definitely Pliocene, but its position within that epoch 

has been controversial. On paleontologic grounds, it is probably slightly 

older than the Bear Bluff Formation at Myrtle Beach, S.C. Because both the 

Goose Creek Limestone and the Bear Bluff Formation are soft, mediumgrained calcarenites from which aragonite has been removed and (or) 

recrystallized, lithic stratigraphers have suggested direct correlation of the 

two units. However, because these units are not known to occur in 

superposition at any locality, resolution of their physical stratigraphic 

relations is impossible at this time.

INTRODUCTION

Sloan (1908) named the "Goose Creek phase" for a section along Goose 

Creek north of Charleston, S.C. Although "phase" is not a modern 

stratigraphic term, it is clear that Sloan's "phases" were intended to 

represent transgressive-regressive episodes of deposition that left behind 

lithologically distinctive deposits across parts of the South Carolina coastal 

plain. As such, this concept conforms closely to the modern concept of 

stratigraphic classification and nomenclature used in the coastal plain. In 

some cases, Sloan's "phases" are ambiguous or actually composite entities, 

but, in the case of the "Goose Creek phase," a type section was designated 

that contains a single, fairly homogeneous, lithologically distinctive deposit 

that appears to represent a single depositional episode. Much of the 

aragonitic material that was once present is leached out, but calcareous and 

phosphatic fossils have persisted and indicate this unit is of Pliocene age.

STRATIGRAPHY

Sloan's (1908) "Goose Creek phase" is herein revived, formalized, and 

renamed the Goose Creek Limestone. The unit's type section in a bluff along 

Goose Creek 0.3 km east of the Seaboard Coastline railroad bridge over 

Goose Creek in the North Charleston 7 l/2-min quadrangle (fig. 31) remains 

unchanged. This section, described in Holmes (1860, p. iv) and in Sloan 

(1908, p. 296, locality 441), is summarized in figure 32. The part of the 

section below sea level was determined from a core (field number CNC-20- 

D), which is stored at the U.S. Geological Survey (Reston). Although the 

type section is only 3 m thick, the unit is known to range up to 8.5 m thick in

'Curator of Natural History, Charleston Museum, Charleston, SC 29401. 

U.S. Geol. Survey Bull. 1529-H, 1982, p. HI37-HI48
HI38 CONTRIBUTIONS TO STRATIGRAPHY

32°45'

10 MILES

I I

5 10 KILOMETERS

FIGURE 31. -Location of type section (X) and isopach map of the Goose Creek Limestone 

in the Charleston, S.C., area. Isopach contour interval 5 m. Distribution of subcrop 

based on nearly 800 auger holes and a few scattered outcrops. 7V2-min quadrangles 

shown by grid and names.
ROBERT E. WEEMS AND OTHERS HI39

»§

0) Q. *

a 3

Sand, medium-grained, orange and 

yellow-mottled, clayey, somewhat 

tougher than the sand below; basal 

contact gradational

Sand, coarse-grained, well-sorted, 

pale-white, soft

Calcarenite, medium-grained, pale-buff-gray 

some quartz and phosphate sand, soft but 

locally indurated around shells into 

nodules, Amusium mortont and Argopecten 

eboreous common, most other mollusks 

are casts, phosphate pebble bed at base

Calcarenite, fine-grained, olive-brown, 

some quartz and phosphate sand, dense

3 6 FEET 

i i I i

1

2 METERS

FIGURE 32.-Type section of the Goose Creek Limestone, Charleston, S.C., area. Location shown on figure 31. No vertical exaggeration.
H140 CONTRIBUTIONS TO STRATIGRAPHY

the Kittredge quadrangle, up to 11.8 m thick in a channel in the Mount Holly 

quadrangle, and up to 18m thick in the Fort Moultrie quadrangle (fig. 31).

In the Charleston area, the Goose Creek Limestone (table 4) is a 

medium- to coarse-grained, quartzose and phosphatic, sparsely shelly, palebuff-gray (wet) to chalk white (dry) calcarenite. Shell material was once 

abundant, but aragonitic forms have been extensively leached, leaving only 

molds and casts. It contains kaolinite in the greater than 2 micron-size 

fraction and both kaolinite and illite-smectite in the less than 2 micron-size 

fraction. Locally, its composition is influenced by the nature of the 

substrate. For example, near Mount Holly, a channel containing Goose 

Creek Limestone is incised deeply into the Eocene Parkers Ferry Member of 

the Cooper Formation (Ward and others, 1979); there, the Goose Creek is 

nearly a calcilutite, like the Parkers Ferry, and contains calcilutite clasts 

obviously derived from the subjacent and adjacent beds of the Parkers 

Ferry. Where the Goose Creek Limestone lies on the Oligocene Ashley 

Member of the Cooper Formation, which is a compact, quartzose and 

phosphatic, fine-grained calcarenite, it is similar to that lithology, though 

coarser grained, much less dense, and light-buff-gray rather than olivebrown. Locally, in the Charleston area, the distribution of the Goose Creek 

is well known (fig. 31). Except for five localities, however, it is known only 

from auger holes.

The fauna of the Goose Creek Limestone is not well known. 

Aragonitic mollusk shells were once abundant but generally have been 

dissolved, leaving only molds and casts. Typically, only calcitic mollusk 

shells have survived in their original form. These include Amusium mortoni, 

Argopecten eboreus, Pecten hemicyclica, Ostrea raveneliana, O. sculpturata, 

and Crasspstrea? sp. (L. W. Ward and B. W. Blackwelder, written commun., 

I979TA. mortoni is consistently present among recently collected 

Charleston Museum specimens from the Goose Creek Limestone at several 

localities near Charleston. Mollusks from Tuomey and Holmes' (1857) 

localities on the Cooper River, Edisto River, and Goose Creek were all 

representative of the Goose Creek Limestone (see Sloan, 1908, p. 285, 

locality 436) and are the only specimens from the fauna of this formation 

that have been figured in the literature. Tuomey (1848, p. 179) and Malde 

(1959, p. 31-32) are the only other publications known certainly to have 

described a part of this fauna.

There are no published reports of Pliocene vertebrate fossils that can 

be assigned readily to the Goose Creek Limestone, but two recent 

discoveries demonstrate that vertebrate remains do occur in place in this 

formation. In 1974, Sanders recovered a partial skeleton of a baleen whale 

from Goose Creek deposits in a pipeline excavation at the South Carolina 

Electric and Gas Company plant on the west bank of the Cooper River in 

Berkeley County, S.C. (USGS North Charleston 7 l/2-min quadrangle) (fig. 

31), approximately 20 km north of Charleston. Preliminary studies by 

Dr. Frank C. Whitmore, Jr. (U.S. Geological Survey), and by Sanders suggest 

that the remains are those of a Minke Whale, Balaenoptera acutorostrata 

(Balaenopteridae, Cetacea), a form occurring today in most of the oceans 

and seas of the world but mainly in temperate and colder waters (Lowery, 

1974). A modern record of this species on the coast of South Carolina has 

been reported by Sanders (1978). During the summer of 1980, James 

Malcom, a local high school student, collected well-preserved elements of a
Table 4. Sediment characteristics of Pliocene units in the Charle

[Numbers refer to localities in figure 34]

Sand, silt, and clay (bulk) (percent)

Raysor Formation

1) Raysor Bridge

2) Cross quarry

3) Canadys Bridge

Goose Creek Limestone

4a) Givhan's Ferry 1

4b) Givhan's Ferry 2

5) K-53

6) Goose Creek

7) Clouter Creek

8) Mark Clark pit

9) Tall Pines

Total 

sand

86

83

55

76

76

78

72

79

78

80

Very 

coarse- to 

coarse Medium

14

II

4

II

14

41

16

1/43

II

2/46

62

64

30

50

57

36

47

35

63

31

Fine- to 

very 

fine

10

8

21

15

5

1

9

1

4

3

Silt and 

clay

14

17

45

24

24

22

28

21

22

20

Total 

sand

63

60

41

23

25

12

10

9

II

27

co

c

 ' Extensive secondary cement, original modal size, probably medium grained.

 / Deposit about 30 cm thick, coarseness and high quartz content probably due to this being 

and (or) bioturbation churning in quartz sand from Pleistocene bed above.
H1 1\2 CONTRIBUTIONS TO STRATIGRAPHY

bird skeleton from Goose Creek Limestone sediments immediately above a 

basal lag deposit of massive phosphate nodules exposed in a ditch paralleling 

the Seaboard Coast Line Railway tracks at a position approximately 1.6 km 

west of S.C. Route 165 (Dorchester Road) in Charleston County (USGS Johns 

Island 7 l/2-min quadrangle) (fig. 31). Now in the collection of the 

Charleston Museum, the specimen is under study by Dr. Storrs Olson of the 

National Museum of Natural History, who has determined it as a gannet, 

Morus sp. (Sulidae, Pelecaniformes). "True gannets (Morus) are of temperate 

range in the North Atlantic or belong to somewhat similar, relatively coolcurrent regions in southern Africa, southern Australia, and New Zealand" 

(Murphy, 1936, p. 827). The gannet M. bqssanus is a fairly common visitor to 

the South Carolina coast from early "October to mid-June (Forsythe, 1978).

Teeth of the shark Carcharodon carcharias occur in the Goose Creek 

Limestone, but those of the late Miocene form Carcharodon megalodon are 

not known to be present except as reworked material in basal lag deposits. 

These circumstances indicate that the Goose Creek is no older than early 

Pliocene in age (Leriche, 1942). However, calcareous nannofossils suggest 

that the Goose Creek is probably no younger than the Reticulofenestra 

pseudoumbilica zone (NNI5), which is considered to be middle Pliocene 

because of the presence of Reticulofenestra pseudoumbilica (Gartner, 1967) 

and Sphenolithus abies Deflandre, 1954. Together these fossil data imply 

that the Goose Creek Limestone is early to middle Pliocene (between 5 m.y. 

and 3 m.y.) in age.

The Goose Creek Limestone occurs extensively along the axis of the 

modern Cooper River and may fill a tectonic trough and (or) an old river 

valley (fig. 31). In the Mount Holly quadrangle, however, the channel-like 

nature of the base of the Goose Creek is more obvious (fig. 33).

STATUS OF THE RAYSOR FORMATION

Cooke (1936 p. 116, locality 216) named the "Raysor marl" on the 

basis of a locality first listed by Sloan (1908, p. 280, locality 366) as being 

present at Raysor Bridge on the Edisto River. The only extant locality that 

seems to closely match Sloan's description, however, is a bluff located at 

what is presently called Canadys Bridge. This bluff, badly overgrown and 

accessible only by drilling, was considered by Blackwelder and Ward (1979) to 

be the original type locality of Cooke's Raysor. The material cored at this 

locality (table 4) is siltier than the Raysor Bridge material (collected by 

Sloan) available at the Charleston Museum but is otherwise comparable. It 

does not appear that Cooke actually saw the type locality; instead, he relied 

entirely on the collections of shells made by Sloan that are now stored in the 

Charleston Museum and at the U.S. National Museum. On the basis of 

mollusk identifications probably made by either Julia Gardner or W. C. 

Mansfield, Cooke at first thought this locality represented a unit distinctly 

older than the "Duplin marl" of North Carolina. At that time, Cooke 

equated the "Duplin" on faunal grounds to most of the Sloan's (1908; "Goose 

Creek marl or phase," though two localities were considered to possibly 

correlate with either the "Duplin" or the Waccamaw. In later years, 

however, Cooke (1945) decided there was no significant age difference 

between his "Raysor marl" and the "Goose Creek phase" and, therefore, 

equated them both with the "Duplin." This status was later accepted by 

Maided 959).
ROBERT E. WEEMS AND OTHERS HI43

8015' 79°45'

32°45

5 10 MILES 

J________I

10 KILOMETERS

FIGURE 33.-Structure countour map of the base of the Goose Creek Limestone in the 

Charleston, S.C., area. Contour interval is 5 m; 0 is sea level.
H144 CONTRIBUTIONS TO STRATIGRAPHY

Recently Blackwelder and Ward (1979) have reinstated the "Raysor 

marl" as the Raysor Formation. They did so in the belief that the Raysor 

was a shell bed with a largely calcareous matrix as opposed to the "Duplin," 

which they considered synonymous with the Yorktown Formation, that has a 

largely clastic matrix. They seem to have derived this apparent difference 

from an analysis of the "Raysor marl" made by Sloan (1908), who stated that 

the rnarl was 80.82 percent calcium carbonate. But collection of matrix 

from several shells in the Sloan collection from Raysor Bridge, now housed 

at the Charleston Museum, has shown that this matrix material actually is 63 

percent medium-grained quartz sand (table 4) excluding clastic silt and clay 

(fig. 34). A sample from Canadys Bridge, though more silty, still contains a 

comparable relative amount of sand (right column, table 4). Since Sloan 

stated the rnarl contained 80.82 percent CaCOo and the marl consisted of 

"shells in a dark blue matrix," we now conclude in retrospect that Sloan 

analyzed a very shell-rich bulk sample and not the matrix alone. This would 

seem to be confirmed by Sloan's referral of the Raysor Bridge locality to his 

"upper Pee Dee phase" (Sloan, 1908, p. 474), which he characterized as 

consisting of "a profusion of shells in a dark blue soft clay matrix which 

encloses variable amounts of sand [italics oursj." Therefore, in bulk sample 

the Raysor is a calcarenite as reported by Blackwelder and Ward, but the 

matrix alone is not.

Blackwelder and Ward (1979) suggested that the stratotype of the 

Raysor Formation be moved to Givhan's Ferry, a locality that neither Cooke, 

originally, nor Sloan believed to be equivalent to the "marl" at Raysor 

Bridge. The dissimilarity of the lithologies at these two sites is confirmed 

by our own studies, which show that the matrix of the pale-buff-gray 

Givhan's Ferry calcarenite contains about 25 percent quartz sand and only 

minor kaolinite and aragonite. This analysis matches well with the Goose 

Creek Limestone (to which Sloan, 1908, referred this locality) and is in 

marked contrast to the Raysor Bridge locality that yielded dark-blue (fresh) 

to gray-green (dry) sediment containing 63 percent quartz sand with about 

twice as much kaolinite, more aragonite, and more hematite than the Goose 

Creek. The material from the Raysor Bridge locality, however, does match 

the material correlated with it at the Martin Marietta Company Berkeley 

quarry (Ward and others, 1979, p. 6), although the matrix of this latter 

material is not so calcareous as they had indicated it to be. Articulated 

shells are filled with very fine grained calcarenite, perhaps because their 

cavities were not widely open to the bottom currents. Discussion with L. W. 

Ward indicates that such shells were the source of the matrix that Ward and 

Blackwelder described, but this material is atypical of the matrix collected 

in bulk quantity. Generally, the yellowish-gray-green shell bed at the 

Berkeley quarry locality also has abundant kaolinite, hematite, and aragonite 

and has a shell-rich matrix that contains 60 percent medium-grained quartz 

sand. Thus, on the basis of bulk matrix, the Berkeley quarry, Canadys 

Bridge, and original Raysor Bridge localities appear to be lithologically 

equivalent, but the proposed neostratotype for the Raysor Formation at 

Givhan's Ferry has a quite different lithology that is readily referred to the 

Goose Creek Limestone as Sloan originally suggested. Therefore, since the 

neostratotype proposed by Blackwelder and Ward (1979) would both totally 

alter the concept of the Raysor as originally established by Cooke (1936) and 

directly conflict with the concept of the "Goose Creek phase" (herein 

proposed as the Goose Creek Limestone) as established originally by Sloan 

(1908), the neostratotype of the Raysor Formation should be abandoned. The
ROBERT E. WEEMS AND OTHERS HI45

10 MILES

0 5 10 KILOMETERS

FIGURE 34.-Known distribution of Pliocene localities in the Charleston, S.C., and inner 

coastal plain area and representative values for quartz sand fraction to total sand fraction (see table 4). Uncircled number indicates location name from table 4; circled 

number indicates ratio of insoluble sand to total sand.
H146 CONTRIBUTIONS TO STRATIGRAPHY

term Raysor Formation should be restricted to lower Pliocene 

biocalcarenites with a quartzose matrix, whereas the term Goose Creek 

Limestone should be restricted to lower to middle Pliocene biocalcarenites 

with a calcareous matrix.

STRATIGRAPHIC RELATIONSHIPS OF THE GOOSE CREEK LIMESTONE 

TO THE RAYSOR FORMATION

The physical stratigraphic relations between the Raysor Formation 

and the Goose Creek Limestone are presently unclear. The relative sparsity 

of quartz, kaolinite, hematite, and aragonite in the Goose Creek Limestone 

at Givhan's Ferry, as compared to the Raysor Formation at Raysor Bridge, 

Canadys Bridge, and Cross quarry, is striking. This difference is much 

greater than any seen within the known outcrop range of either unit (fig. 

34). It is plausible that these two units represent onshore and offshore 

facies, respectively, of a single depositional cycle that graded very rapidly 

from a nearshore clastic phase to a shelf carbonate phase. For example, 

rapid gradation from a nearshore terrigenous phase to a shelf carbonate 

phase over a distance of less than 20 km has been documented for the 

Holocene sediments off the coast of Belize (Purdy and others, 1975). 

Conversely, the two units could represent two separate transgressions within 

early to middle Pliocene time and may have no gradational interrelation at 

all. Although a large fauna was collected from Raysor Bridge by Sloan 

(Blackwelder, 1967), the poor preservation of the Goose Creek fauna 

hampers meaningful detailed mollusk comparisons between the two. So far, 

the Raysor has yielded no diagnostic nannofossils. If future drilling furnishes 

new sections between the known Raysor and Goose Creek outcrop belts, the 

physical stratigraphic relations may become clear. In the meantime, all we 

can demonstrate is that the units are lithologically different where they are 

known. Should future work show the boundary to be gradational, 40 percent 

quartz in the sand-size matrix is tentatively suggested as the arbitrary 

lithologic boundary unless future field mapping shows some other parameter 

that better characterizes the change from the typical quartzose calcarenite 

(10-15 percent quartz-sand content) of the Goose Creek Limestone to the 

shelly quartz sand (60-65 percent quartz-sand content) of the Raysor 

Formation.

STRATIGRAPHIC RELATIONS OF THE GOOSE CREEK LIMESTONE 

TO THE BEAR BLUFF FORMATION

DuBar and others (1974) proposed the name Bear Bluff Formation for 

Pliocene-age calcarenites exposed in the Myrtle Beach, S.C., area, 130 km 

northeast of the Charleston area. Analyses of samples from this area 

indicate an age for this unit within the range of the Discoaster surculus zone 

to the D. brouweri zone (NNI6-I8). This would make this unit late Pliocene 

in age Tbetween 2.9 m.y. and 1.7 m.y. old) and suggests that the Bear Bluff in 

its type area is younger than the Goose Creek. It is not known if these two 

units are related as transgressive portions of a single depositional cycle or if 

they represent discrete transgressive events separated by an unconformity. 

In either case, they are lithologically very similar. Because physical 

stratigraphic relations between the Goose Creek Limestone and the Bear 

Bluff Formation are unclear, because the two areas are widely separate, and 

because the name Goose Creek is the older name, we favor the use of the 

name Goose Creek in at least the Charleston area until such time as the
ROBERT E. WEEMS AND OTHERS H147

relation between the two units is firmly established. Although there is 

provision in the code of stratigraphic nomenclature (American Commission 

on Stratigraphic Nomenclature, 1970) for retention of younger, wellestablished names of stratigraphic units in preference to older, little used 

names, we suggest in this case that, if the two units do prove to be 

lithologically continuous, the older name, Goose Creek, should be retained. 

The Goose Creek was lithologically well defined by Sloan, so its subsequent 

abandonment based on purely paleontological correlations should not be 

grounds for considering it an invalid lithologic unit.

If the possible age differences among the Raysor, the Goose Creek, 

and the Bear Bluff are correct, a threefold chronostratigraphic division of 

the Pliocene in South Carolina is indicated, as suggested by Campbell and 

others (1975). In South Carolina, these authors recognized the Raysor and 

the Bear Bluff but referred to the middle unit as the "Natural Well member 

of the Duplin," apparently in reference to Natural Well, N.C. Their middle 

unit may be equivalent to the Goose Creek Limestone, judging from its 

position relative to the Raysor and the Bear Bluff. Again, the name "Natural 

Well member" has been applied only recently, and the Goose Creek is by far 

the older term.

REFERENCES CITED

American Commission on Stratigraphic Nomenclature, 1970, Code of 

stratigraphic nomenclature: American Association of Petroleum 

Geologists, 22 p.

Blackwelder, B. W., 1967, Invertebrate fossil collections at the Charleston 

Museum: Geologic Notes, v. I I, no. 2, p. 5-19.

Blackwelder, B. W., and Ward, L. W., 1979, Stratigraphic revision of the 

Pliocene deposits of North and South Carolina: Geologic Notes, v. 23, 

no. I, p. 33-49.

Campbell, L. D., Campbell, S. C., Colquhoun, D. J., and Ernissee, J. J., 1975, 

Plio-Pleistocene faunas of the central Carolina coastal plain: Geologic 

Notes, v. 19, no. 3, p. 51-78.

Cooke, C. W., 1936, Geology of the coastal plain of South Carolina: U.S. 

Geological Survey Bulletin 867, 196 p.

___1945, Geology of Florida: Florida Geological Survey Bulletin 29, 339 p.

DuBar, J. R., Johnson, H. S., Thorn, Bruce, and Hatchell, W. 0., 1974, 

Neogene stratigraphy and morphology, south flank of the Cape Fear 

Arch, North and South Carolina, ]n_ Oaks, R. Q., Jr., and DuBar, J. R., 

eds., Post-Miocene stratigraphy, central and southern Atlantic Coastal 

Plain: Logon, Utah, Utah State University Press, p. 139-173.

Forsythe, D. M., 1978, Birds (of the coastal zone of South Carolina) hi 

Zingmark, R. G., ed., An annotated checklist of the biota of the coastal 

zone of South Carolina: Columbia, University of South Carolina Press, 

p. 277-295.
H148 CONTRIBUTIONS TO STRATIGRAPHY

Holmes, F. S., I860, Post-Pliocene fossils of South Carolina: Charleston, 

S.C., 122 p.

Leriche, Maurice, 1942, Contribution a ['etude des faunes ichthyologiques 

marines des terrains tertiares de la Plaine Cotiere Atlantique et du 

centre des Etats-Unis: Societe Geologique du France Memoire, v. 45, 

n.s., t. 20, fasc. 2-4.

Lowery, G. H., Jr., 1974, The mammals of Louisiana and its adjacent 

waters: Baton Rouge, Louisiana, Louisiana State University Press, 

p. 1-565.

Malde, H. E., 1959, Geology of the Charleston phosphate area, South 

Carolina: U.S. Geological Survey Bulletin 1079, 105 p.

Murphy, R. C.,, 1936, Oceanic birds of South America: New York, American 

Museum of Natural History, 2 vol., 1-1245.

Purdy, E. G., Pusey, W. C., Ill, and Wantland, K. F., 1975, Continental Shelf 

of Belize Regional shelf attributes, in Wantland, K. F., and Pusey, W. 

C., Ill, Belize shelf Carbonate seaTments, clastic sediments, and 

ecology: American Association of Petroleum Geologists Studies in 

Geology, no. 2, p. 1-39.

Sanders, A. E., 1978, Mammals (of the coastal zone of South Carolina) ]n_ 

Zingmark, R. G., ed., An annotated checklist of the biota of the coastal 

zone of South Carolina: Columbia, University of South Carolina Press, 

p. 296-308.

Sloan, Earle, 1908, Catalogue of the mineral localities of South Carolina: 

South Carolina Geological Survey Bulletin 2 (reprinted 1958), ser. 4, 

505 p.

Tuomey, Michael, 1848, Report on the geology of South Carolina: Columbia, 

S.C., 293 p.

Tuomey, Michael, and Holmes, F. S., 1857, Pliocene fossils of South 

Carolina, consisting of descriptions and figures of Polyparia, 

Echinodermata and Mollusca; Charleston, S.C., 152 p., 30 pi.

Ward, L. W., Blackwelder, B. W., Gohn, G. S., and Poore, R. Z., 1979, 

Stratigraphic revision of Eocene, Oligocene, and lower Miocene 

formations of South Carolina: Geologic Notes, v. 23, no. I, p. 2-32.