y^x 1 ft * 1 Gnesquethawan Stratigraphy 

(Lower and Middle Devonian)

, GEOLOGICAL SURVEY PROFESSIONAL PAPER
Onesquethawan Stratigraphy 

(Lower and Middle Devonian) 

of Northeastern Pennsylvania

By Jack B. Epstein

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1337

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1984
DEPARTMENT OF THE INTERIOR 

WILLIAM P. CLARK, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Library of Congress Cataloging in Publication Data

Epstein, Jack Burton, 1935-

Onesquethawan stratigraphy (Lower and Middle Devonian) of northeastern Pennsylvania.

(Geological Survey professional paper; 1337)

Bibliography: p.

Supt. of Docs, no.: I 19.16:1337

1. Geology, Stratigraphic Devonian. 2. Geology Pennsylvania Monroe County. 3. Geology Pennsylvania Carbon

County. I. Title. II. Series. 

QE665.E67 1984 551.7'4'0974825 84-600160

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

604 South Pickett Street, Alexandria, VA 22304
CONTENTS

Abstract 

Introduction 

Acknowledgments 

History of nomenclature 

Onesquethawan rocks 

Onesquethawan rocks in Godfrey Ridge 

Esopus Formation 

Schoharie Formation 

Buttermilk Falls Limestone 

Foxtown Member 

McMichael Member 

Stroudsburg Member 

Onesquethawan rocks in Cherry to Stone Ridges 

Schoharie and Esopus Formations, undivided -

Palmer-ton Sandstone 

Buttermilk Falls Limestone 

Regional correlations 

Environments of deposition 

Measured sections 

References cited 

9

11

14

14

16

20

22

23

26

31

ILLUSTRATIONS

FIGURE 1. Map of outcrop belt of Onesquethawan rocks and location of measured sections and other localities 2

2. Chart of development of nomenclature for the Onesquethawan in northeastern Pennsylvania 3

3. Correlation chart of Onesquethawan rocks in northeastern Pennsylvania 5 

4-6. Photographs of:

4. Esopus Formation showing rock cleavage 6

5. Siltstone in the Schoharie Formation 8

6. Taonurus in the Schoharie Formation 9

7. Photomicrograph of the Schoharie Formation 10

8. Photograph showing limestone and crinoid columnal in the Foxtown Member of the Buttermilk Falls Limestone 11

9. Photomicrograph of the Foxtown Member of the Buttermilk Falls Limestone 12 

10-12. Photographs showing:

10. Limestone and shale in the McMichael Member of the Buttermilk Falls Limestone 13

11. Chert and limestone in the Stroudsburg Member of the Buttermilk Falls Limestone 14

12. Roadcut along Pa State Rte. 33 at Saylorsburg 16

13. Photomicrograph of a spicularite in the Schoharie Formation 17

14. Photograph showing spheroidal weathering in the Palmerton Sandstone 18

15. Photomicrograph of the Palmerton Sandstone 19

16. Photographs showing Taonurus in the Esopus and Schoharie Formations 25

ONESQUETHAWAN STRATIGRAPHY (LOWER AND MIDDLE DEVONIAN)

OF NORTHEASTERN PENNSYLVANIA

ByjACKB. EPSTEIN

ABSTRACT

Lower and Middle Devonian clastic rocks and limestones of the 

Onesquethawan Stage in the Valley and Ridge province of the Lehigh 

and Delaware Valleys of eastern Pennsylvania include the Esopus and 

Schoharie Formations, the Buttermilk Falls Limestone, and the Palmerton Sandstone. The Buttermilk Falls Limestone in Godfrey Ridge 

in the eastern part of the area is divided into three new members, from 

oldest to youngest: the Foxtown, McMichael, and Stroudsburg 

Members. The Palmerton Sandstone is present only southwest of Godfrey Ridge where it replaces the upper part of the Schoharie Formation 

and the basal Buttermilk Falls beds. The entire Onesquethawan sequence thins from about 560 feet (171 m) near Stroudsburg to 195 feet 

(59 m) along the northeast extension of the Pennsylvania Turnpike near 

Bowmanstown, a distance of 37 miles (60 km). The Tioga Ash Bed, 

which marks the top of the Onesquethawan Stage, lies immediately 

above the Buttermilk Falls near the Lehigh River and 27 feet (8 m) 

below the top of the Buttermilk Falls at Stroudsburg. These rocks were 

extensively leached by pre-Wisconsinan weathering southwest of the 

Wisconsinan terminal moraine near Saylorsburg. Outcrops are sparse 

in this area of deep weathering. The members of the Buttermilk Falls 

Limestone cannot be distinguished, and the Esopus and Schoharie Formations cannot be separated regionally, although they can be differentiated at a few localities of good exposure.

INTRODUCTION

Onesquethawan rocks in eastern Pennsylvania consist of less than 200 to more than 550 feet (61-168 m) of 

shaly siltstone, sandstone, and limestone that lies between the Ridgeley Sandstone of the Oriskany Group 

below and the Marcellus Shale above. They have been 

mapped for more than 35 miles (56 km) in the Delaware 

River and Lehigh River area (fig. 1). Some of the resistant Onesquethawan rocks alternate with the Ridgeley 

Sandstone in holding up the crest of a line of ridges 

known by various names: Godfrey Ridge in the northeast and Cherry, Chestnut, Stony, and Stone Ridges, 

southwest of a 2-mile-wide fold near Bossardsville.

The sequence is thickest in Godfrey Ridge near 

Stroudsburg where it consists of silty shale and shaly 

siltstone of the Esopus Formation at the base and 

grades up into calcareous siltstone of the Schoharie

Formation and younger argillaceous limestone and 

calcareous shale of the Buttermilk Falls Limestone. In 

passing southwest from Godfrey Ridge to the other 

ridges, the sequence thins, and the Palmerton Sandstone replaces parts of the Schoharie Formation and 

Buttermilk Falls Limestone. The Tioga Ash Bed, which 

defines the top of the Onesquethawan Stage, crops out 

at the base of the Marcellus Shale near the Lehigh River 

and 27 feet (8 m) below the top of the Buttermilk Falls 

Limestone near Stroudsburg.

The units in the southwestern part of the area lie beyond the limits of Wisconsinan glaciation and have been 

leached deeply by pre-Wisconsinan weathering. As a 

consequence, the sandstones are friable, and the shales 

and limestones have weathered to a deep clay saprolite. 

Outcrops are sparse, making stratigraphic comparisons 

with the fresh exposures on Godfrey Ridge somewhat 

difficult. Three newly named members of the Buttermilk Falls Limestone cannot be distinguished southwest of Godfrey Ridge. Also, the Esopus and Schoharie 

Formations are difficult to separate southwest of Godfrey Ridge, and they have been combined for purposes 

of mapping. In the past, the combined Esopus and 

Schoharie were called the "Bowmanstown Chert," but 

that name has been abandoned (Epstein and Epstein, 

1967).

The sinuous outcrop pattern of Onesquethawan rocks 

in eastern Pennsylvania is due to complex folding. The 

folds are asymmetric and have wavelengths averaging 

between 1,000 and 1,500 feet (305-457 m). They are 

mostly upright with some overturned limbs in Godfrey 

Ridge (see Epstein, 1973); others are recumbent with 

some limbs that are rotated more than 180° in Cherry 

Ridge and ridges to the southwest (see Epstein and 

others, 1974). An overview of the structure of the entire 

area is given in Epstein and Epstein (1969). Moderate 

structural thinning and thickening of stratigraphic 

units has occurred, depending on the lithology of the 

units and position of the units in the folds. Consequently, some of the thickness variations (see fig. 3)

i
ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

75°15'

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75°45'

FIGURE 1. Location of and TVi-minute quadrangle coverage of outcrop belt of Onesquethawan rocks between the Lehigh and Delaware Rivers 

in eastern Pennsylvania Numbers refer to measured sections and other localities listed on p. 2-3.

may be structural. Detailed maps of most of the area are 

given in Epstein (1973,1978), Epstein and Sevon (1978), 

and Epstein and others (1974). Localities of measured 

sections and some of the more important exposures in 

the area follow:

1. Schoharie Formation and parts of the Esopus Formation and Foxtown Member of the Buttermilk 

Falls Limestone (measured section 1) in roadcut 

along U.S. 209, 300 feet (91 m) northwest of 

Buttermilk Falls, type locality of the Buttermilk 

Falls Limestone, East Stroudsburg quadrangle.

2. Esopus Formation and part of the Schoharie Formation along abandoned railroad grade on north 

side of Brodhead Creek, 1,500 feet (457 m) west of 

Minisink Hills, Pa, Stroudsburg quadrangle.

3. Foxtown and McMichael Members of the Buttermilk Falls Limestone, Esopus Formation, and 

parts of the Schoharie Formation and Stroudsburg 

Member of the Buttermilk Falls Limestone (measured section 2) in abandoned quarry 100 feet (30 m)

south of the intersection of U.S. 209 and 1-80 and 

along bluffs north of the Erie-Lackawanna Railroad, 1,000 feet (305 m) southwest of the quarry, 

Stroudsburg quadrangle. The quarry is shown as a 

gravel pit on the Stroudsburg quadrangle.

4. Buttermilk Falls Limestone and part of the Schoharie Formation (measured section 3) along ErieLackawanna Railroad, 5,000 feet (1,524 m) south 

of the East Stroudsburg Post Office, type section 

of the three members of the Buttermilk Falls 

Limestone, Stroudsburg quadrangle.

5. Schoharie Formation and parts of the Esopus Formatoin and Foxtown Member of the Buttermilk 

Falls Limestone, Eureka Stone Co. quarry, 3.2 

miles (5.1 km) northeast of Saylorsburg, Saylorsburg quadrangle.

6. Buttermilk Falls Limestone, Palmerton Sandstone, 

Schoharie Formation, and part of the Esopus Formation (measured section 4) along Pa State 

Route 33 (also shown as Pa State Route 115 on
HISTORY OF NOMENCLATURE

some maps), 3,000 feet (914 m) east of Saylorsburg, Saylorsburg quadrangle.

7. Buttermilk Falls Limestone and part of the Palmerton Sandstone, clay pits of Universal Atlas Cement Co., 3.5 miles (5.6 km) east of Kunkletown, 

Pa., Kunkletown quadrangle.

8. Palmerton Sandstone and Schoharie and Esopus 

Formations, undivided, roadcut 1,600 feet (488 m) 

southwest of Little Gap, Pa., Palmerton quadrangle (Swartz and Swartz, 1941, p. 1153).

9. Buttermilk Falls Limestone, Palmerton Sandstone, 

and Schoharie and Esopus Formations, undivided, in abandoned mine tunnel at Hazard, Pa., 

Lehighton quadrangle (Swartz and Swartz, 1941, 

p. 1148).

10. Palmerton sandstone and Schoharie and Esopus 

Formations, undivided, in cuts along the Central 

Railroad of New Jersey and highway immediately 

above, 3,200 feet (975 m) southeast of Bowmanstown, Pa., Lehighton quadrangle (Swartz and 

Swartz, 1941, p. 1146-1147).

11. Buttermilk Falls Limestone, Palmerton Sandstone, 

Schoharie Formation, and Esopus Formation 

(measured section 5), Northeast Extension of the 

Pennsylvania Turnpike, 2,600 feet (792 m) southwest of Bowmanstown, Pa., Lehighton quadrangle (see also Willard, 1957, and Sevon, in 

Epstein and others, 1974, p. 400-406).

ACKNOWLEDGMENTS

I thank Wallace de Witt, Jr., and W. A. Oliver, Jr., for 

helping make the report more readable by their 

thorough reviews. J. M. Berdan, A. G. Harris, and J. W. 

Huddle helped in age determinations by their identifications of ostracodes and conodonts in the Buttermilk 

Falls Limestone. A. G. Harris helped in measurements 

of some of the sections.

HISTORY OF NOMENCLATURE

The naming of the Onesquethawan rocks in eastern 

Pennsylvania has had a long and complex history (fig. 

2). Rogers (1858) developed a Latin nomenclature that 

describes the age of rocks in Pennsylvania by referring 

to divisions of the day, from dawn (Primal) to nightfall 

(Serai). Thus, he named the rocks herein described the 

Post-Meridian Series ("afternoon"). These names did 

not survive the First Pennsylvania Survey of Rogers, 

although many stratigraphic details are credible today. 

White (1882) and Chance (1882) first applied the New 

York names Caudi-galli grit and Corniferous limestone

to the rocks of eastern Pennsylvania. The Caudi-galli 

was named for the trace fossil Taonurus, which resembles a rooster's tail. The New York name Onondaga 

was first applied by Kindle (1912) to rocks that were 

finally named the Buttermilk Falls Limestone by 

Willard (1938), although several later workers still used 

the name Onondaga, such as on the geologic map of 

Pennsylvania (Gray and others, 1960; and Inners, 1975, 

who examined these rocks in New York, New Jersey, 

and Pennsylvania). Kindle also substituted the name 

Esopus shale for the Caudi-galli. The petrology of the 

Esopus between New York and Pennsylvania is discussed by Rehmer (1976). Cooper and others (1942) first 

used the Schoharie shale in eastern Pennsylvania, although the earliest stratigraphic details were published 

by Herpers (1950a), Trexler (1953), Johnson (1957, 

1959), and Johnson and Southard (1962).

In the Lehigh Valley, Swartz and Swartz (1938) first 

demonstrated that rocks that were previously considered to be the Oriskany sandstone of Early Devonian 

age also included a younger sandstone that is separated 

from the Oriskany by a "chert" of Middle Devonian 

age. These two younger units were named the Palmerton sandstone and Bowmanstown chert by Swartz (in 

Willard and others, 1939). The Bowmanstown was later 

dropped by Epstein and Epstein (1967) who showed 

that it was similar to the Esopus and the Schoharie farther to the northeast, except that it was generally more 

deeply weathered. The Buttermilk Falls was informally 

subdivided into three mappable members in Godfrey 

Ridge by Epstein (1971). These are, from oldest to 

youngest, the Foxtown, McMichael, and Stroudsburg 

Members. The Palmerton Sandstone and the members 

of the Buttermilk Falls Limestone are herein adopted 

for use by the U.S. Geological Survey.

Onesquethawan rocks were placed in the Onondaga 

formation of the Hamilton group by Willard (1936) 

because of faunal and lithologic similarities to the 

Hamilton. Willard later abandoned this designation and 

raised the Onondaga to group rank (Willard and others, 

1939, 1947; Willard, 1938, 1957), as did Dyson (1956).

Minor units that have been recognized in this group of 

rocks include the Tioga Ash Bed (Roen and Hosterman, 

1981), which marks the top of the Onesquethawan 

Stage (Dennison and Textoris, 1966), and the Hazard 

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ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

limestone in central Pennsylvania, but later Willard and 

others (1939) reinstated the name for noncherty beds 

near Bowmanstown. Because of the uncertainty of 

continuity of these beds with the type Selinsgrove in 

central Pennsylvania and because the weathered rocks 

at Bowmanstown contain some chert, they are herein referred to as the Buttermilk Falls Limestone. Willard 

also recognized the Palmerton and the Bowmanstown 

but apparently included them in his Esopus (Willard 

and others, 1939, p. 145, 151, 154, and 333). Willard's 

statements and diagrams indicate that he placed 87 feet 

(27 m) of Esopus above the Palmerton and below the 

Hazard paint ore. His conclusions create three inconsistencies. (1) One definition of Willard's Esopus ranks 

the Esopus as a separate unit above the Palmerton; 

another places the Palmerton and the Bowmanstown as 

members of the Esopus. This inconsistency is shown 

diagrammatically in figure 2 of this report. (2) Only 5 

feet (1.5 m) of rock, not 87 feet (27 m) is present between 

the Palmerton and Hazard along the Pennsylvania 

Turnpike (see measured section 5). Willard's error was 

noted also by Swartz and Swartz (1941, p. 1180). (3) 

Whether Willard meant the Hazard to be a member of 

the Esopus (Willard and others, 1939, p. 154, table 21) 

or a part of the Selinsgrove (Willard and others, 1939, 

p. 151) is not clear.

ONESQUETHAWAN ROCKS

The rocks described in this report are the correlatives 

of the Esopus, Schoharie, and Onondaga of New York 

that comprise the Onesquethawan Stage. Their type 

section is west of Clarksville, Albany County, N.Y., 

near Onesquethaw Creek in the Helderberg Mountains (Cooper and others, 1942). Onesquethawan rocks 

in eastern Pennsylvania lie between the Ridgeley Sandstone of the Oriskany Group below and the Marcellus 

Shale of the Hamilton Group above. Willard (in Willard 

and others, 1939) proposed the Stroudsburgian Stage 

for these rocks; he did not recognize the Schoharie. His 

stage name has not been used by subsequent workers. 

The latest correlations (Oliver and others, 1969) place 

the Esopus, Schoharie, and Palmerton in the Lower 

Devonian and the Buttermilk Falls in the Middle Devonian, although other workers have placed all the units in 

the Middle Devonian (Willard, in Willard and others, 

1939; Jones and Cate, 1957; Sevon, 1970). These age 

assignments may not be entirely accurate because field 

relations suggest that part of the Palmerton Sandstone 

may be laterally equivalent to the basal part of the Buttermilk Falls. Faunal lists for Onesquethawan rocks in 

eastern Pennsylvania are given by White (1882), 

Prosser (1892), Kindle (1911, 1912), Swartz and Swartz

(1941), Willard (1936, 1938), Willard and others (1939), 

Willard and Whitcomb (1938), and Inners (1975). Figure 

3 shows the stratigraphic relations of these rocks in the 

report area.

ONESQUETHAWAN ROCKS IN GODFREY RIDGE

ESOPUS FORMATION

Darton (1894) named the Esopus shale for exposures 

along Esopus Creek, near Esopus, N.Y. In the Stroudsburg area, White (1882) measured 250 feet (76 m) of his 

Caudi-galli grit. Willard (1936, 1938) reported more than 

250 feet (76 m) of the Esopus and later (Willard and 

others, 1939) revised the figure to more than 300 feet 

(91 m). Swartz and Swartz (1941) measured 275 feet 

(84 m) of Esopus at Experiment Mills in Godfrey Ridge 

along Brodhead Creek (fig. 1, loc. 2). In their measurements, these workers included rocks herein assigned to 

the Schoharie Formation. Johnson (1957) and Johnson 

and Southard (1962), who recognized the Schoharie 

Formation, believed the Esopus to be more than 200 

feet (61 m) thick in the Stroudsburg area.

The Esopus is 181 feet (55 m) thick in bluffs north of 

the Erie-Lackawanna Railroad, 1 mile (1.6 km) east of 

East Stroudsburg (fig. 1, loc. 3). On the basis of a series 

of cross sections, the Esopus appears to maintain this 

approximate thickness to the southwest termination of 

Godfrey Ridge. The Esopus is a medium-gray (N5) to 

dark-gray (N3), medium-gray- (N5) weathering, shaly to 

finely arenaceous siltstone with lesser silty shale and 

minor calcareous siltstone. Cleavage is very well developed, masking sedimentary features to some degree (fig. 

4). The rock is laminated, but bedding is indistinct in 

many places. It generally is burrowed extensively with 

the trace fossil Taonurus, which is also common in the 

basal part of the Schoharie (see figs. 6 and 16). Brachipods are present but are not abundant. Moderateyellowish-brown (10172 5/4) to dark-yellowish-orange 

(10 YR 6/6) iron staining is distinctive. For practical 

separation from the overlying Schoharie into which it 

grades, the Esopus is decidedly less calcareous or noncalcareous, it has better developed cleavage, it has characteristic iron staining, and, when hit with a hammer, it 

emits a dull thud as compared to the more resonant ring 

of the more massive Schoharie. Rare beds of calcareous 

siltstone, similar to those of the Schoharie, were seen in 

the lowerpart of the Esopus in Godfrey Ridge north of 

Bossardsville.

In thin section, the Esopus is composed mainly of 

shaly graywacke siltstone and consists of medium- to 

coarse-silt-sized quartz grains (about 40-50 percent),
sw. -i-O Marcellus I Shale of the I Hamilton

0 5 10 MILES 

r-Hr-r1

0 5 10 15 KILOMETERS

75°45' 75°30'

11 ? 

"10

3& 41°00'

INDEX MAP SHOWING LINES OF SECTION

I Measured thickness 

! Estimated thickness

Thickness reported by other workers 

"^x Exposure of Tioga Ash Bed

-600

15 MILES 

I

I 

20 KILOMETERS

FIGURE 3. Correlation chart of Onesquethawan rocks in northeastern Pennsylvania
ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

FIGURE 4. Well-developed slaty cleavage in the Esopus Formation along U.S. 611 on the north slope of Godfrey Ridge immediately south of 

Stroudsburg. Cleavage (cl) dips about 75° to the southeast (to the left), and bedding (b) dips about 30° in the same direction.

muscovite and chlorite (15-30 percent), calcite (probably averaging less than 3 percent), plagioclase, chert, 

and angular to rounded tourmaline and zircon (rare) in a 

fine-silt to clay matrix consisting mostly of quartz, 

muscovite, and chlorite. Opaque minerals, including 

pyrite and leucoxene, comprise about 1 percent. The 

quartz is ragged and replaced with muscovite and 

chlorite in pressure-shadow areas of cleavage. Many of 

the muscovite, chlorite, and some quartz grains are 

oriented parallel to cleavage.

The Esopus underlies some of the highest parts of 

Godfrey Ridge. Good exposures are numerous, such as 

those along U.S. 209 (fig. 1, loc. 1), along the abandoned 

railroad grade west of Minisink Hills (fig. 1, loc. 2), at 

Foxtown Gap and on the north slope of Godfrey Ridge 

along U.S. 611 south of Stroudsburg, along the road 

east of Pine Grove Lake north of Stormville, and in the 

Eureka Stone Co. quarry (fig. 1, loc. 5).

The base of the Esopus is in sharp contact with the 

underlying Ridgeley Sandstone of the Oriskany Group

and is unconformable (Willard, 1936; Cleaves, 1937; 

Cooper and others, 1942; Jones and Gate, 1957; Epstein 

and Epstein, 1969). This interpretation is supported by 

the faunal break, abrupt lithic changes, and inferred different environments of deposition discussed in the section "Environments of Deposition."

SCHOHARIE FORMATION

Vanuxem (1840) named the Schoharie for exposures 

in Schoharie County, N.Y. At Buttermilk Falls (fig. 1, 

loc. 1), Herpers (1950a) described 72 feet (22 m) of calcareous siltstone at the top of his Esopus Formation 

and placed them in his "X-beds," a transitional interval 

between the Esopus and Buttermilk Falls Limestone. 

These beds were later assigned to the Schoharie Formation by Johnson (1957), although the name Schoharie 

was first used by Cooper and others (1942) in eastern 

Pennsylvania The base of the Schoharie, as recognized
ONESQUETHAWAN ROCKS

by Johnson (1957) and Johnson and Southard (1962), is 

placed at the lowest conspicuous calcareous siltstone 

or mudstone overlying the Esopus. Accepting this contact, which also coincides with the base of the lowest 

massive siltstone, I measured 103 feet (31 m) of 

Schoharie near Buttermik Falls (fig. 1, loc. 1; measured 

section 1). It thins at a rate of approximately 2 feet per 

mile to the Eureka Stone Co. quarry (fig. 1, loc. 5) where 

it is 97 feet (30 m) thick. Johnson (1957) noted a rate of 

thinning of 4 feet per mile from Port Jervis, N.Y., where 

the Schoharie is 271 feet (83 m) thick, to Buttermilk 

Falls, where he measured 102 feet (31 m).

The Schoharie in Godfrey Ridge is predominantly a 

medium-gray (N5) to grayish-black (Af2), thin-bedded to 

very thick bedded, laminated and massive, fairly evenly 

bedded, calcareous siltstone with lesser amounts of finegrained sandy siltstone. It weathers medium gray (N5) 

to medium dark gray (N4) and light olive gray (5Y 6/1). 

The more calcareous beds weather lighter than the silty 

beds. Beds range from a few inches to as much as 6 feet 

(2 m) thick (fig. 5). Dark-gray (Af3) chert, which weathers 

light gray (A/7), is scattered throughout as rounded and 

irregular nodules and lenses as much as 2 inches (5 cm) 

thick. The chert is more abundant toward the top of the 

unit. The upper beds in the Schoharie appear to become 

more cherty and limy toward the southwest termination 

of Godfrey Ridge; therefore, the Schoharie is gradational into the overlying Buttermilk Falls Limestone. 

Horizontal burrows (Taonurus) are abundant in the 

lower half (fig. 6). Brachiopods are common. The base of 

the formation, according to Johnson (1957), is marked 

by a zone of Pacificocoelia aeutiplicata (Conrad), a fossil 

that is typically found in his "Carlisle Center" facies. 

Inners (1975) subdivided the Schoharie Formation in 

Godfrey Ridge into the Carlisle Center Member (containing abundant Taonurus), below, and the AquetuckSaugerties Members, undivided (with vertical burrows), 

above. These subdivisions could not be used in field 

mapping. The Schoharie is transitional into the Esopus. 

The boundary locally is placed within a 10- to 20-foot interval with difficulty, especially in the fresh rocks exposed in the Eureka Stone Co. quarry. Slaty cleavage is 

locally conspicuous in the Schoharie but is generally not 

as well developed as in the underlying Esopus.

In thin section (fig. 7), calcite as microspar and as 

sparry rhombs comprises 25 to 60 percent of most of the 

rock in the Schoharie. Quartz (35-65 percent) is etched 

and generally occurs as single grains, but a few composite grains of quartz and grains of chert were noted. 

Muscovite and chlorite make up less than 5 percent of 

the rock. Plagioclase feldspar (less than 1 percent) and 

rare tourmaline, zircon, and opaque minerals, including 

pyrite and leucoxene, are accessory minerals. Rare phosphatic shell material was seen in one section.

The Schoharie is fairly well exposed in Godfrey Ridge. 

It generally underlies high parts of the ridge. In addition to the locality near Buttermilk Falls, good exposures are found in an abandoned quarry 0.9 mile 

(1.4 km) west of Minisink Hills (fig. 1, loc. 2), along U.S. 

Highway 611 south of Stroudsburg, in the ErieLackawanna railroad cut nearly 1 mile (1.6 km) south of 

the East Stroudsburg Post Office (fig. 1, loc. 4), along 

the north slope of Godfrey Ridge throughout the area, 

and along Pa. Highway 33 1.4 miles (2.3 km) west of 

Bossardsville. It is completely exposed in the quarry of 

the Eureka Stone Co. (fig. 1, loc. 5), where it is processed 

for crushed stone.

BUTTERMILK FALLS LIMESTONE

The type locality of the Buttermilk Falls Limestone is 

at Buttermilk Falls on Marshall Creek (fig. 1, loc. 1). 

Willard (in Willard and others, 1939) named the unit 

and believed it to be about 200 feet (61 m) thick. At the 

type locality (measured section 1), only the lower 25 feet 

(8 m) are exposed. Elsewhere, as in the railroad cut of 

the Erie-Lackawanna Railroad (fig. 1, loc. 4), the Buttermilk Falls is 272 feet (83 m) thick and consists of three 

mappable members a medial calcareous silty shale 

separating two cherty limestones. These members are 

herein named, in ascending order, the Foxtown, 

McMichael, and Stroudsburg Members. Inners (1975) 

recognized a similar subdivision but added an additional member to the top of the sequence (see fig. 2).

Foxtown Member

The type section of the Foxtown and of the other two 

members of the Buttermilk Falls Limestone is in the 

railroad cut of the Erie-Lackawanna Railroad, nearly 1 

mile (1.6 km) south of the East Stroudsburg Post Office 

(fig. 1, loc. 4; measured section 3). The name is taken 

from Foxtown Hill on Godfrey Ridge where the member 

is exposed in nearly vertical beds along U.S. 611.

The Foxtown consists of wavy irregularly bedded and 

lenticular, medium-gray (N5) weathering to mediumdark-gray (M>), cherty limestone in beds 1 inch (3 cm) to 

2 feet (0.6 m) thick (fig. 8). Grain size is generally fine 

(fig. 9), although very coarse grains are not uncommon. 

The limestone is interbedded with medium-dark-gray 

(A/4), calcareous, evenly bedded shale and siltstone in 

beds 1 inch (3 cm) to 1 foot (0.3 m) thick and contains 

dark-gray (N3) to grayish-black (N2) chert. The chert in 

the lower half is in irregular nodules 0.5 to 6 inches 

(1-5 cm) in diameter. Chert is more abundant in the upper half where it makes up more than 50 percent of the
10 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

FIGURE 5. Evenly bedded siltstone in the upper half of the Schoharie Formation in roadcut along U.S. 209 near Buttermilk Falls (fig. 1, loc. 1). 

More massive beds are seen at the top of the section. Lighter weathering beds are more calcareous.

unit. It is interbedded with calcareous argillite 1 to 2 

inches (2.5-5 cm) thick and limestone pods 2 to 6 inches 

(5-15 cm) in diameter. The chert contains varying 

amounts of calcite and mica (fig. 9).

Large crinoid columnals (fig. 8), as much as 1 inch 

(2.5 cm) in diameter and 4 inches (10 cm) long, are conspicuous in the lower half of the Foxtown Member. 

Oliver (1962; written commun., 1962) traced zones of 

large crinoid columnals in the base of his Edgecliff 

Member at the bottom of the Onondaga Limestone from 

Onondaga, N.Y., to Port Jervis, N.Y. The similar 

crinoid marker bed at the bottom of the Buttermilk 

Falls of eastern Pennsylvania is the equivalent of the 

basal part of the Onondaga of southeastern New York. 

Although stratigraphic relations have not been worked 

out between Monroe County, Pa., and southeastern 

New York, the facies changes alone are sufficient to 

justify the new member names in the Stroudsburg 

quadrangle.

At the type section, the base of the Foxtown Member 

is marked by a 1-foot- (0.3-m-) thick bed of medium-gray

(M>), medium- to very coarse grained limestone in 

abrupt contact with the underlying Schoharie Formation. In the western part of Godfrey Ridge, the boundary between the Foxtown and the Schoharie is transitional through about 6 feet (1.8 m) of cherty calcareous 

siltstone and silty limestone. In this area, coarse sand 

grains more than 3 mm (0.1 in.) in diameter are present 

in basal Foxtown beds, apparently heralding proximity 

to the Palinerton Sandstone in Cherry Ridge 1.3 miles 

(2 km) to the southeast. I believe that the basal part of 

the Foxtown and the upper part of the Schoharie are 

lateral equivalents of the Palmerton. Also in the western part of Godfrey Ridge, crinoid columnals are not as 

abundant as they are to the northeast along the ridge. 

The columnals are especially scarce in the southwesternmost exposures of the Foxtown 2,000 feet (610m) 

south of Hamilton Square and 1.35 miles (2.2 km) southwest of Bossardsville in the Saylorsburg quadrangle.

The Foxtown Member is 82 feet (25 m) thick at the 

type section. In the abandoned quarry south of 1-80 

and 1,200 feet (366 m) west of where the highway
ONESQUETHAWAN ROCKS 11

FIGURE 6. Cross section of the trace fossil Taonurus, believed to be 

a horizontal feeding burrow, in the lower half of the Schoharie 

Formation, in roadcut along U.S. 209 near Buttermilk Falls (fig. 1, 

loc. 1).

crosses Brodhead Creek (fig. 1, loc. 3, the SlaterCanfield quarry, according to Johnson (1957) who 

assigned these beds to the Schoharie Formation), the 

Foxtown is 80 feet (24 m) thick, and the lower 45 feet 

contains the large crinoid columnals.

The Foxtown Member is fossiliferous. Brachiopods 

are common, and a large silicified ostracode faunule was 

recovered by dissolving the rock in dilute acetic acid. 

The following ostracodes were identified by J. M. 

Berdan and A. G. Harris (U.S. Geological Survey):

Acathoscapha navicula (Ulrich)

Aechmina sp.

Amphizona sp.

Bairditesl sp.

Beecherella sp. cf. B. carinata Ulrich

Bufina sp.

Camdenidea

Hottinella sp.

Kirkbyella (Berdanella) sp. cf. K (B.) unicornis 

(Coryell and Malkin)

Kirkbyella sp.

Menoeidina sp.

New genus aff. Pachydomella thlipsuroidea Swain

Parabolbina sp.

Ranapeltis trilateralis Swartz and Swain

Ranapeltis sp. cf. R. unicarinata

Ranapeltis sp.

Richinat sp.

Rudderina sp.

Strepulites bifurcatus (Bassler)

Tricorninal sp.

Tubulibairdia sp.

Tubulibairdia'i sp.

Ulrichia pluripuncta Swartz and Swain (Coryell and

Malkin)

According to Berdan (written commun., 1963), these 

have affinities with forms described from the Hamilton 

Group and the Onondaga Limestone. Thus, it is probable 

that the collection represents beds of Onondaga age 

(Middle Devonian) rather than of Schoharie age (Early 

Devonian).

The Foxtown Member generally forms slight topographic rises on the north slope of Godfrey Ridge. It is 

coarsely jointed and has supplied large boulders, some 

of which exceed 30 feet (9 m) in length, to glacial drift to 

the south. In addition to the localities mentioned, good 

exposures are found at the foot of Godfrey Ridge along 

the junction of U.S. 611 and Pa. State Route 191, at the 

west edge of the Stroudsburg quadrangle near 

McMichael Creek, and along Pa State Route 33 at the 

southwest end of Godfrey Ridge where about 15 to 40 

feet (4.6-12 m) of the Foxtown forms a resistant cap on 

the Schoharie Formation.

McMichael Member

The member is named for McMichael Creek north 

of Godfrey Ridge. At the type section, along ErieLackawanna Railroad (fig. 10, it is 41 feet (12.5 m) thick, 

and at the abandoned quarry at locality 3 of figure 1 it is 

42 feet (13 m) thick. It consists of evenly bedded to 

lenticular, medium-gray (M>) to medium-dark-gray t/V4), 

weathering medium-gray (M>), calcareous, partly silty, 

fossiliferous shale in beds 2 inches (5 cm) to 1 foot 

(0.3 m) thick, and interbedded medium-gray (M>), finegrained fossiliferous biomicrite and biomicrudite in 

beds, lenses, and nodules 1 to 3 inches (2.5-8 cm) thick. 

Fossils are abundant and include crinoid, trilobite, bryozoan, and brachiopod debris and ostracodes. Silicified 

ostracodes were recovered at the type section and were 

identified by J. M. Berdan and A. G. Harris (U.S. Geological Survey). They are of probable Onondaga age and 

include:

Aechmina sp.

Amphizona sp. cf. A. asceta Kesling and Copeland

Bairdiocyprisl sp.

Bairditesl sp.

Bollia disceratina Swartz and Swain
12 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

FIGURE 7. Photomicrograph (crossed polarizers) of very coarse grained quartzose calcisiltite in the Schoharie Formation, 50 feet (15 m) below 

the contact with the overlying Buttermilk Falls Limestone, from roadcut along U.S. 209 near Buttermilk Falls, unit 4 of meaured section 1 (fig. 

1, loc. 1). The rock contains about 50 percent calcite (ca) as microspar and recrystallized rhombs; etched, predominantly simple quartz (sq) 

(about 45 percent) with a few composite grains (eg); and minor muscovite (m), chlorite, and plagioclase feldspar (p).

B. planojugosa Swartz and Swain

Bufina sp.

Euglyphellal sp.

Eukloedenellctf sp.

Favulella dicarinella Swartz and Swain

F. favulosa (Jones)

Hollinella sp. aff. H. antespinosa (Ulrich)

Kirkbyella (Berdanella) sp. cf. K. (B.) unicornis

(Coryell and Malkin) 

Pachydomella sp.

Parabolbinaparvinoda Swartz and Swain 

Parabolbina sp.

Ranapeltis trilateralis Swartz and Swain 

Reversocyprisl sp. 

Rhopalonellus sp. 

Richina sp.

Rishonal sp.

Rudderina sp.

Strepulites bifurcatus (Bassler)

Tricornina sp.?

Tubulibairdia sp.

Tubulibairdicft sp.

Ulrichia elongata Swartz and Swain

lUlrichiapluripuncta Swartz and Swain 

The McMichael Member is poorly exposed except for 

the localities mentioned. It is not exposed for 7.6 miles 

(12.2 km) southwest of the type section until 2,000 feet 

(610 m) south of Hamilton Square in the Saylorsburg 

quadrangle where it is identified with some uncertainty. 

The McMichael generally forms a topographic swale between the cherty limestones above and below. The lower 

boundary is gradational.
13

FIGURE 8. Irregularly bedded cherty limestone in the upper half of the Foxtown Member of the Buttermilk Falls Limestone, in roadcut along 

Brown Street, 5,000 feet (1,524 m) northeast of the hospital in East Stroudsburg. Inset shows 1-inch-diameter crinoid columnal from the 

lower part of the Foxtown Member at the type section on the Erie-Lackawanna Railroad (fig. 1, loc. 4).

Stroudsburg Member

This member is named for Stroudsburg, Pa., where 

excellent exposures are seen along 1-80 (see Epstein and 

Epstein, 1969, fig. 23ff). In the abandoned quarry at 

locality 3 of figure 1, the lower 15 feet (4.6 m) are exposed, and, at the type section (fig. 11; measured section 

3) 149 feet (45.4 m), probably the entire thickness of the 

member, is exposed. The Stroudsburg consists of irregularly bedded, medium-gray (N5) to medium-dark-gray 

(A/4), weathering light-gray (AP7) to medium-light-gray 

(M>), fossiliferous, fine- to medium-grained, locally argillaceous limestone in beds and lenses 1 inch (2.5 cm) to 1 

foot (0.3 m) thick and dark-gray (A/B) to grayish-black 

(N2) chert in irregular beds, lenses, and pods 0.25 inch 

(6.4mm) to 1 foot (30 cm) thick. The upper 15 feet 

(4.6 m) at the type section and near Stroudsburg contains several beds, which are 3 to 6 inches (8-15 cm) 

thick, of medium-gray (N5) to medium-light-gray (M>), 

weathering light-gray (AP7), medium to very coarse

grained limestone (mostly biosparrudite). These coarser 

limestones were named the Echo Lake Member by Inners (1975). This name has not been used because the 

rocks are not mappable due to poor exposure. They contain abundant brachipod, coral, and crinoid debris and 

some conodonts. The conodonts were identified by A. G. 

Harris and J. W. Huddle (U.S. Geological Survey) and 

include Icriodus expansus Branson and Mehl and a new 

subspecies of Icriodus latericrescens Branson and Mehl. 

These indicate that the Stroudsburg Member is no older 

than the upper part of the Moorehouse Member of the 

Onondaga Limestone of New York.

The Tioga Ash Bed, first recognized by Inners (1975) 

in the Stroudsburg area, crops out about 27 feet (8.2 m) 

below the top of the Buttermilk Falls Limestone along 

the Erie-Lackawanna Railroad south of East Stroudsburg (measured section 3) and along 1-80 just east of 

the Pa. State Route 191 overpass. The bed ranges between 10 inches (.25 m) and 1.3 feet (0.4 m) in thickness 

and is similar in general appearance to calcareous shales
14 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

FIGURE 9. Photomicrograph (plane-polarized light) of cherty biomicrite (light areas) and biomicrite (dark areas) in the Foxtown Member of the 

Buttermilk Falls Limestone, near Buttermilk Falls, unit 5 of measured section 1, 15 feet (4.6 m) above the contact with the Schoharie Formation. Ostracode is partly filled with micrite (m), a probable geopetal structure, and sparry calcite (s). Shell is also partly filled with quartz (q) 

and calcite (c) that are alined parallel to rock cleavage. Other samples of the Foxtown are biomicrudites, partly neocrystallized to microspar 

and pseudospar.

lower in the section. The Tioga is a light-olive-gray (5Y 

6/1) to medium-olive-gray (5Y 5/1) and medium-gray 

(N5) to medium-dark-gray (N4), generally noncalcareous, tuffaceous siltstone to very fine grained sandstone and crystal tuff that weathers medium light gray 

(M>) and grayish orange (10 YR 7/4) to moderate yellowish brown (10 YR 5/4). It contains rare brachipods. The 

bed is characterized by abundant bleached mica flakes 

that are visible to the naked eye. These are normally biotite elsewhere (Dennison and Textoris, 1971; Roen and 

Hosterman, 1982), but in the Stroudsburg area, X-ray 

and thin-section analyses show that the biotite has been 

altered to ripidolite.

As seen in thin section, the biotite is the most abundant crystal in the tuffaceous sediment. It is subhedral 

to euhedral, lath shaped, and altered to limonite and 

chlorite. Less common single crystal quartz grains are 

euhedral to subhedral, and many have corroded edges.

They are as much as 0.3 mm long. Elongate and curved 

grains of microcrystalline quartz are probably altered 

glass shards. Subsidiary equant grains of aggregate 

muscovite, as much as 0.2 mm long, are partial replacements of feldspar. Uncommon calcite grains, slightly 

longer than 0.1 mm, are partly replaced and rimmed by 

quartz. Minor minerals include euhedral apatite and zircon, as much as 0.2 mm long. Opaque minerals include 

pyrite and probably magnetite in irregular, framboidal, 

and euhedral grains as much as 0.06 mm long. The 

matrix makes up more than 50 percent of the rock and 

consists of chert and microcrystalline muscovite that 

may be alteration products of volcanic glass. The rock is 

laminated and irregularly laminated; this suggests 

some reworking by currents after deposition.

Because the Tioga Ash Bed marks the top of the 

Onesquethawan Stage, the uppermost 27 feet (8.2 m) of 

the Buttermilk Falls is Cazenovian in age and correlates
ONESQUETHAWAN ROCKS 15

 t*JW

FIGURE 10. Evenly bedded and lenticular limestone (light) and calcareous shale (dark) in the McMichael Member of the Buttermilk Falls 

Limestone at the type locality along the Erie-Lackawanna Railroad, nearly 1 mile (1.6 km) south of the East Stroudsburg Post Office (fig. 1, 

loc. 3). The beds are overturned and dip to the southeast (to the right) more steeply than the conspicuous cleavage in the shale. Note refraction of the cleavage in the limestone.

with the Seneca Member of the Onondaga Limestone of 

New York (the Tioga is found between the Seneca and 

underlying Moorehouse Member there). This corroborates the age of the uppermost part of the Buttermilk 

Falls in the Stroudsburg area suggested by the conodonts. As will be noted later (see p. 23), the Tioga is 

found at the base of the Marcellus Shale and just above 

the Buttermilk Falls along the northeast extension of 

the Pennsylvania Turnpike (see fig. 3). Therefore, the 

top of the Buttermilk Falls becomes younger to the 

northeast in the area of this report.

The McMichael and Stroudsburg Members have a 

gradational boundary. The upper boundary of the 

Stroudsburg Member is nowhere exposed in Godfrey 

Ridge but is probably in abrupt contact with shales and 

calcareous shales and siltstones of the Union Springs 

Shale and Stony Hollow Members of the Marcellus 

Shale.

The Stroudsburg Member is well exposed at the localities mentioned above, as well as in several small hills 

that rise above the valleys of McMichael and Brodhead 

Creeks and south of Hamilton Square near the southwest end of Godfrey Ridge.
16 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

FIGURE 11. Unevenly but distinctly bedded chert (dark) and limestone (light) in the Stroudsburg Member of the Buttermilk Falls Limestone 

at the type section along the Erie-Lackawanna Railroad south of East Stroudsburg (fig. 1, loc. 4). Beds are overturned and dip to the 

southeast (to the left). Poorly developed cleavage dips gently to the southeast.

ONESQUETHAWAN ROCKS IN CHERRY TO STONE RIDGES

Several important changes occur in Onesquethawan 

rocks in passing from Godfrey Ridge to Cherry Ridge 

and the ridges to the southwest. The units become thinner, and the Palmerton sandstone appears and thickens 

to the southwest (fig. 3). Southwest of the Wisconsinan 

terminal moraine, which crosses Cherry Ridge near 

Saylorsburg (fig. 1), the rocks have been weathered to 

depths greater than 150 feet (46 m) in places, forming 

sedimentary-rock saprolites. Southwest of Bossardsville, exposures become scarcer, and the members of the 

Buttermilk Falls cannot be distinguished. Some of these 

changes have been noted by Swartz and Swartz (1941), 

although some of their interpretations differ in detail 

from the results presented here.

SCHOHARIE AND ESOPUS FORMATIONS, UNDIVIDED

Swartz (in Willard and others, 1939) named the Bowmanstown chert for about 67 feet (20 m) of chert and 

fossiliferous argillaceous sandstone above the Oriskany 

and below the Palmerton exposed along the State 

highway 0.5 mile (0.8 km) east of Bowmanstown. Prior 

to this identification, both the Bowmanstown and 

Palmerton were thought to be part of the Oriskany. 

Swartz and Swartz (1941) recognized that the 

Bowmanstown correlated with the lower half of their 

Esopus in Godfrey Ridge. Willard (1957) recognized 

that Swartz's Bowmanstown could be divided into a 

lower shale and siltstone, which he called the Esopus, 

and an overlying blocky chert, which he called the 

Bowmanstown. Epstein and Epstein (1967) noted that
ONESQUETHAWAN ROCKS 17

these rocks are similar to the Esopus and Schoharie in 

the Stroudsburg area and could be mapped into each 

other. Therefore, they discarded the name "Bowmanstown" and termed the rocks Schoharie and Esopus Formations, undivided, a designation also followed by 

Epstein and Epstein (1969), Epstein and others (1974), 

Epstein and Sevon (1978), and Berg and others (1983).

The Schoharie and Esopus Formations generally 

become thinner west of Saylorsburg (fig. 3). Thicknesses 

reported by different workers at any single locality vary 

considerably, no doubt because of differing stratigraphic boundary interpretations and complex folding 

and some faulting that make measurements somewhat 

inaccurate. For example, along the Northeast Extension 

of the Pennsylvania Turnpike and near Bowmanstown 

(fig. 1, Iocs. 10 and 11), where I measured nearly 48 feet 

(15 m) of these rocks (measured section 5), Willard 

(1936) measured 4 to 10 feet (1-3 m), and Swartz and 

Swartz (1941) reported 67 feet (20 m). At Little Gap, 

where folding is complex, Cleaves (in Willard and 

others, 1939) reported 54 feet (16 m), whereas Swartz 

and Swartz (1941) measured 111 feet (34 m). At Saylorsburg, 68 feet (21 m) of the Schoharie-Esopus are exposed 

(measured section 4), and the unit is probably about 175 

feet (53 m) thick, on the basis of construction of cross 

sections. Near Stroudsburg, the combined Esopus and 

Schoharie Formation are about 285 feet (87 m) thick.

Because of poor exposures, the Schoharie and Esopus 

cannot be mapped separately west of Bossardsville. The 

two formations are distinguishable, however, in deep 

roadcuts (fig. 1, Iocs. 6,10, and 11) and at a few places in 

between. The Esopus is dark, finer bedded, and shalier 

than the overlying Schoharie, which is more massive 

(fig. 12) and lighter in color, apparently due to weathering of more abundant calcium carbonate (calcium carbonate is much more abundant in the Schoharie than in 

the Esopus in the unweathered sections on Godfrey 

Ridge).

The Esopus is at least 35 feet (11 m) thick at Saylorsburg and thins to 11 feet (3 m) along the Pennsylvania 

Turnpike. Silty shale and shaly siltstone are the dominant lithic types. They are dark gray (N3) on fresher surfaces and are weathered to many colors at most localities, including very light gray (A/8), light greenish gray 

(5GY 7/1), grayish red (5R 4/2), and dark yellowish 

orange (1QYR 6/6). The Esopus is laminated to fine 

bedded (beds average 2 to 3 inches (5-8 cm) in thickness, 

but some are 1 foot (30 cm) thick). The trace fossil 

Taonurus is abundant. The contact with the underlying 

Ridgeley Sandstone of the Oriskany Group is abrupt, 

whereas the boundary with the overlying Schoharie is 

gradational through interbedded shaly siltstone and 

blocky siltstone. The boundary with the Schoharie is 

placed at the base of a prominent blocky siltstone that 

weathers lighter than the siltstones in the Esopus.

The Schoharie Formation is thinner than in Godfrey 

Ridge. It is 33 feet (10 m) thick at Saylorsburg and 37 

feet (11 m) thick along the Pennsylvania Turnpike. It 

consists of evenly bedded siltstone to very fine grained 

sandstone with rare medium-grained sandstone. At 

Saylorsburg (loc. 6, fig. 1), a 3-inch- (8-cm-) thick very 

coarse grained sandstone bed is included in the 

Schoharie near the disconformable contact with the 

overlying Palmerton Sandstone (fig. 12; measured section 4). A somewhat similar unit with more sandstone 

along the Pennsylvania Turnpike (fig. 1, loc. 1) is placed 

in the Palmerton (measured section 5).

The Schoharie is medium light gray (M>) to dark gray 

(N3) on fresher surfaces and weathers white (M)) to light 

gray (AT7) and very pale orange (10YR 8/2), pale 

yellowish orange (10 YR 8/6) to dark yellowish orange 

(WYR 6/6), light brown (5YR 5/6) to grayish brown 

(SYR 3/2), and pale red (WR 6/2) to moderate reddish 

brown (IQR 4/6). Chert nodules that are 1 to 3 inches 

(3-8 cm) in diameter and irregular chert beds and lentils 

as much as 3 inches (8 cm) thick are common. These are 

dark gray (N3) and weather very light gray (N8) to 

medium gray (M>). The Schoharie contains numerous 

brachiopod fragments and hexactinellid sponge spicules 

(fig. 13). Most of the spicules are multirayed and contain 

axial canals (identification by J. Keith Rigby, Jr., 

Brigham Young University, written commun. to W. A. 

Oliver, Jr., U.S. Geological Survey, January 1981). The 

horizontal trace fossil Taonurus is abundant, especially 

in the lower part. Scattered quartz grains, 0.1 to 0.4 

inches (3-10 mm) in diameter, are found in some beds. 

Fresher rocks are not calcareous but are siliceous and 

have not been leached as have adjacent rocks that presumably contains appreciable calcium carbonate. The 

Schoharie appears to be more siliceous and blocky to the 

southwest (see fig. 84 of Sevon, in Epstein and others, 

1974), but this trend is masked by the extensive weathering of the rocks throughout the area. The Schoharie 

also contains some shaly siltstone in beds 1 to 6 inches 

(3-15 cm) thick, which are similar to beds in the underlying Esopus. Dark-yellowish-brown (IQYR 5/2) ironstone concretions, which are as much as 5 inches (13 cm) 

in diameter, are abundant at the top of the Schoharie 

near Saylorsburg. An 8-inch- (20-cm-) thick grayish-red 

(5R 4/2) siltstone bed lies 21 feet (6 m) above the base of 

the Schoharie along the Pennsylvania Turnpike.

Swartz's Bowmanstown chert was named for beds 

southwest of Godfrey Ridge that were later equated 

with the Esopus and Schoharie in Godfrey Ridge by 

Epstein and Epstein (1967). The units in both areas are 

dissimilar mainly because of the more extensive and 

deep weathering southwest of the Wisconsinan terminal 

moraine. However, similar lithic types and sedimentary 

features may be traced between the two areas. Moreover, there are a few localities on Godfrey Ridge where
18 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

Figure 12. Roadcut along Pa State Route 33 at Saylorsburg (fig. 1, loc 6; measured section 4) showing dark thin-bedded siltstone of the 

Schoharie Formation (Ds), which overlies the massive Palmerton Sandstone (Dp). The contact between the Esopus (De) and Schoharie is 

abrupt but appears uneven due to irregularities in the exposure. The Schoharie-Palmerton contact is unconformable with a relief of about 

2.7 feet (0.8 m). The beds dip about 50° to the southeast and are overturned.

the Esopus and the Schoharie are weathered deeply and 

resemble the equivalent rocks to the southwest. For 

example, on the road crossing Godfrey Ridge 1.2 miles 

(1.9km) northeast of Bossardsville, the Esopus is 

weathered to light shades of gray and is varicolored. 

Also, chert float from the nearby Schoharie Formation 

has white weathering rinds similar to weathered chert in 

ridges southwest of the Wisconsinan terminal moraine. 

Thin sections show that lath-shaped sponge spicules 

made of microcrystalline quartz, as much as 0.3 mm 

long, are fairly common in the Schoharie (fig. 13). 

Angular quartz and chert grains make up most of the 

rocks examined. Muscovite and lesser chlorite grains as 

much as 0.2 mm long comprise 20 percent of some 

rocks. Limonite and hematite are common products of 

weathering. Rare cellophane fragments and idiomorphic 

tourmaline and zircon make up the heavy mineral fraction. Sevon (in Epstein and others, 1974) also noted 

epidote and garnet. A few shale fragments were seen.

All of the brachiopod fragments are replaced by silica, 

and chert has replaced much of the quartz. This silicification gives many outcrops their blocky resistant 

character.

In addition to the good exposures mentioned above, 

there are only a few other scattered outcrops of the 

Schoharie and Esopus. These are generally near the 

crest or on the steep south slopes of the ridges, in the 

clay and sand pits south and east of Kunkletown, and in 

the sand pits near Palmerton and Germans. Elsewhere, 

these rocks were mapped by tracing siltstone and shale 

float between the sandstone of the Ridgeley and 

Palmerton (see Epstein and others, 1974; Epstein, 1978; 

and Epstein and Sevon, 1978).

PALMERTON SANDSTONE

The Palmerton Sandstone was named by Swartz and 

Swartz (1941) after it was first determined (Swartz and
ONESQUETHAWAN ROCKS 19

FIGURE 13. Photomicrograph (plane-polarized light) of spicularite or very fine grained sandstone made up predominantly of angular quartz 

and chert grains and abundant hexactinellid sponge spicules of monocrystaline quartz. From a small quarry in massive Schoharie Formation 

(beds are as much as 4 feet (1.2 m) thick), in Stony Ridge just west of Mill Creek in Aquashicola, Palmerton quadrangle.

Swartz, 1938; Swartz in Willard and others, 1939) to be 

a unit that is separable from underlying sandstones of 

the Oriskany Group, with which it was previously confused. The name was derived from exposures near 

Palmerton, but a type section was not designated. The 

best exposure, one that could serve as a reference section, is along the Pennsylvania Turnpike through Stone 

Ridge (fig. 1, loc. 10; measured section 5). A more detailed measured section is given by Sevon (in Epstein 

and others, 1974). The Palmerton Sandstone is thickest 

in Stony Ridge (fig. 1) and thins in both directions along 

strike (fig. 3). It is 108 feet (33 m) thick along the Pennsylvania Turnpike, although slightly greater thicknesses were reported by several workers, including 120 

feet (37 m) by Cleaves and Willard (in Willard and 

others, 1939), 126 feet (38 m) by Swartz and Swartz 

(1941), and 125 feet (39 m) by Dyson (1956). It thickens 

to 140 feet (43 m) in a mine tunnel at Hazard, according 

to Swartz and Swartz (1941). Northeastward, it thins to 

66 feet (20 m) along Pa. State Route 33 at Saylorsburg

and to about 40 feet (12 m), 1.6 miles (2.6 km) northeast 

of Pa. State Route 33. The Palmerton thins to a feather 

edge along the northeast end of Cherry Ridge and is absent in Godfrey Ridge.

The Palmerton Sandstone is fairly uniform in its 

petrographic characteristics throughout its area of outcrop. It is generally a medium-dark-gray (N4) to very 

light gray (N8), medium- to very coarse grained sandstone and conglomeratic sandstone with rounded quartz 

pebbles as much as 0.75 inch (19 mm) long. A few fineto very fine grained sandstone and siltstone beds are in 

the basal few feet. These rocks weather pale yellowish 

orange (1QYR 8/6) to dark yellowish orange (WYR 6/6) 

and very pale orange (10 YR 8/2) to grayish orange 

(10 YR 7/4). Bedding is generally poorly developed and 

massive. Beds range up to 8 feet (24 m) thick at 

Saylorsburg and to more than 20 feet (6.1 m) thick along 

the Pennsylvania Turnpike; however, some parts of the 

Palmerton are thin bedded and partly laminated.

The Palmerton is quartz rich. The sand grains are well
20 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

rounded to subangular. Silica cement in places creates a 

dense vitreous quartzite, and limonite is a common but 

minor cement. Cementation is variable in outcrops so 

that the Palmerton forms resistant ledges in places, 

whereas elsewhere it deteriorates into a loose sand.

The basal few feet are generally iron stained and locally contain moderate-brown (5YR 4/4) ironstone concretions 1 to 2 inches (3-5 cm) in diameter. The contact 

with the underlying Schoharie Formation is sharp, and 

at Saylorsburg it is irregular and disconformable, with a 

relief of about 2.7 feet (0.8 m). The contact generally is 

placed at the base of the lowest sandstone above the 

siltstones of the Schoharie, whereas at Saylorsburg, 

predominant siltstone and lesser sandstone in the lower 

2.8 feet (0.9 m) are placed in the upper part of the 

Schoharie.

The Palmerton is the best and most continuously exposed stratigraphic unit in Cherry, Chestnut, Stony, 

and Stone Ridges. It underlies the crests of these ridges 

in most places and also is well exposed in several sand 

quarries between Germans and the area east of Kunkletown (fig. 14). Sevon (1970) discussed the geology and 

economics of this sand resource. The Palmerton generally crops out as a rib several tens of feet high. In 

many places, it is characterized by bare loose blocks 

that are so jumbled by frost heaving that obtaining 

structural attitudes is difficult or impossible. It is 

everywhere prominently jointed, and, locally, weathering has produced spheriodal masses (fig. 14).

As seen in thin section, quartz makes up more than 95 

percent of all rocks examined. The quartz occurs mainly 

as single grains with slightly to strongly undulose extinction due to postdepositional deformation. Many 

grains are composite vein quartz with comb structure 

and abundant vacuoles. Vermicular chlorite is found in a 

few. Recrystallized composite grains (probably from a 

quartzite source) and chert are minor components. 

Many of the grains have original rounded to subrounded outlines, but most are angular due to interpenetration of the contacts (fig. 15). Interstitial quartz forms 

a cement, commonly in optical continuity with the 

enclosing grains. Limonite cement is minor, and no

FIGURE 14. Spheroidal weathering in massive Pahnerton Sandstone in pits of the Universal Atlas Cement Co., 3.5 miles (5.6 km) east of 

Kunkletown (fig. 1, loc. 7). Prominent vertical and more poorly defined horizontal joints control the shape of the large weathered spheroids.
ONESQUETHAWAN ROCKS 21

FIGURE 15. Photomicrograph (crossed polarizers) of poorly sorted very coarse grained conglomeratic orthoquartzite in the Palmerton Sandstone, roadcut along Pa State Route 33 near Saylorsburg (fig. 1, loc. 6). Rounded to subangular grains are mostly single-grained quartz. The 

large composite vein-quartz grain is more than 3 mm (0.1 in.) long. Many of the grain boundaries are indented, but quartz overgrowths cement some grains. Quartz makes up more than 99 percent of the rock.

samples studied contain more than 4 percent. Rare 

heavy minerals include zircon, hornblende, and pyrite.

In the past the Palmerton sandstone has been confused with the Ridgeley Sandstone of the Oriskany 

Group. It differs from the Ridgeley by being more poorly bedded, and it lacks the abundant spiriferid molds 

that are so characteristic of the Ridgeley. The Palmerton, however, does contain rare favositid coral and 

crinoid columnals molds as much as 4 inches (10 cm) 

long and rarer brachiopod molds. Sevon (1970, and in 

Epstein and others, 1974) also noted that the Palmerton 

has a unimodal grain-size distribution and is generally 

well sorted (although some samples are poorly sorted as 

shown in fig. 15), whereas the Oriskany is mostly 

bimodal, with modes of coarse sand and pebble-sized 

grains. The Palmerton is readily separated from the 

Oriskany where the intervening Esopus and Schoharie 

are exposed or distinguishable by float.

The latest correlations (Oliver and others, 1967, 1969) 

place the Palmerton at the top of the Lower Devonian,

with the overlying Buttermilk Falls Limestone in the 

Middle Devonian. However, the Palmerton does not 

contain diagnostic fossils, and, as discussed below and 

as shown in figure 3, the upper part of the Palmerton 

probably grades laterally into the lowermost part of the 

Buttermilk Falls. Thus, the Palmerton probably spans 

the Lower-Middle Devonian boundary.

The Palmerton is everywhere sandwiched between the 

Buttermilk Falls Limestone above and Schoharie Formation below. In Godfrey Ridge, where the Palmerton 

is absent, the Buttermilk Falls immediately overlies the 

Schoharie. The only evidence in Godfrey Ridge that 

may herald the lateral presence of the Palmerton to the 

southwest is the occurrence of isolated coarse quartz 

grains in the lowermost beds of the Foxtown Member of 

the Buttermilk Falls. These quartz grains disappear 

along strike to the northeast. Crinoid columnals are 

common in the lower half of the Foxtown Member and 

become scarcer to the southwest along Godfrey Ridge 

as the outcrop area of the Palmerton is approached. The
22 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

Palmerton contains scarce comminuted crinoid columnals that, together with the presence of quartz grains in 

the Foxtown, suggest that the upper part of the Palmerton and basal part of the Buttermilk Falls are laterally 

continuous.

At Saylorsburg, basal Palmerton beds unconformably cut into the Schoharie, and the uppermost part of 

the Schoharie contains interbedded sandstone of 

Palmerton type. This vertical relation suggests lateral 

equivalence of the basal Palmerton and uppermost 

Schoharie.

Along the Pennsylvania Turnpike (loc. 11), the basal 5 

feet (1.5 m) of the overlying Buttermilk Falls Limestone 

contains conodonts of early Middle Devonian age. 

These rocks underlie the Tioga Ash Bed and correlate 

with the upper half of the Moorehouse Member of the 

Onondaga Limestone of New York. Thus, the Palmerton in the western area of this report may range from 

Schoharie, through Edgecliff and Nedrow, to Moorehouse in age. In the eastern end of Cherry Ridge, the 

Palmerton is thinner and may have a much narrower 

age range, since it replaces upper Schoharie and lower 

Foxtown rocks. If the lower part of the Foxtown 

Member of the Buttermilk Falls is continuous with the 

Edgecliff Member of the Onondaga Limestone of New 

York, on the basis of the lateral continuity of the 

distinctive crinoid-bearing beds (Oliver, 1962), then the 

Palmerton may range from Schoharie to Edgecliff in 

age in the eastern part of the report area

The area where the Palmerton disappears and is replaced by other Onesquethawan rocks is about 1 mile 

(1.6 km) southwest of Bossardsville. As mentioned, the 

Palmerton is about 40 feet (12 m) thick in Cherry Ridge, 

1.6 miles (2.6 km) northeast of the roadcut along Pa 

State Route 33 in Saylorsburg. It crops out for an additional 0.9 mile (1.4 km) to the northeast along the ridge 

crest, to a point that is 0.9 mile (1.4 km) S. 10° W. from 

Bossardsville. There the Palmerton apparently is folded 

to the northwest for about 1 mile (1.6 km), as indicated 

by a topographic high in that direction, but this area is 

covered by thick glacial drift. In the next exposure of 

Onesquethawan rocks, 0.3 mile (0.5 km) to the north, 

the Palmerton is missing, and the Buttermilk Falls is in 

contact with the Schoharie. The possibility that the 

Palmerton-bearing sequence in Cherry Ridge has been 

telescoped structurally onto the Palmerton-absent sequence in Godfrey Ridge is discounted because there is 

no evidence for faulting along strike in the Bossardsville 

area Abundant exposures are in many quarries of the 

Bossardsville Limestone of Silurian age, demonstrating 

that a major dislocation does not exist (see Epstein, 

1980, fig. 8). Thus, the lateral change from the Palmerton Sandstone in Cherry Ridge to equivalent rocks in 

Godfrey Ridge occurs within a distance of 1 mile 

(1.6 km) in an area of no exposures.

BUTTERMILK FALLS LIMESTONE

The three members of the Buttermilk Falls Limestone 

that are mappable in Godfrey Ridge cannot be distinguished to the southwest because of poor exposure and 

extensive leaching of the original cherty limestone and 

calcareous shale. This leaching has produced deep 

residual clay (sedimentary rock saprolite) because of 

pre-Wisconsinan weathering (Epstein and Hosterman, 

1969). The clay is found only southwest of the Wisconsinan terminal moraine (fig. 1). Presumably, the clay extended farther to the northeast but was stripped by the 

advancing Wisconsinan glacier, exposing the fresh 

bedrock that is now present in Godfrey Ridge.

The Buttermilk Falls is 263 feet (80 m) thick at 

Saylorsburg (measured section 4; fig. 1, loc. 6), similar 

to the thickness at the southwest end of Godfrey Ridge 

(fig. 3). It thins rapidly to 63 feet (19 m) at the pits of the 

Universal Atlas Cement Co., east of Kunkletown (fig. 1, 

loc. 7), and to 40 feet (12 m) along the Pennsylvania 

Turnpike (measured section 5; fig. 1, loc. 10). At the latter locality, previous workers reported 27 to 29 feet 

(8.2-8.8 m) (Chance, 1882; White, 1882; and Willard, in 

Willard and others, 1939), whereas Willard (1957) 

reported slightly more than 50 feet (15 m).

At most exposures, the Buttermilk Falls is a deeply 

weathered silty and shaly clay with rare fine-grained 

sand and minor clayey, shaly siltstone. Much of the clay 

is iron stained with limonite and hematite. Nodular and 

irregularly bedded chert is common. The nodules are as 

much as 3 inches (8 cm) in diameter, and some pods are 

up to 1 foot (30 cm) long. The chert beds are as much as 

3 inches (8 cm) thick. The chert weathers to mottled 

very dusky red (5ft 2/6) and very light gray (NS) to 

medium gray (M>). Fresher chert is dark gray (A/3) to 

grayish black (N2).

The clays of the Buttermilk Falls Limestone weather 

light gray (JV7) to white (A/9), yellowish gray (5F 8/1) to 

grayish yellow (5Y 8/4), and many shades of orange, red, 

and purple, including very pale orange (lOFft 8/2) to 

moderate yellowish brown (10 YR 5/4), pale yellowish 

orange (lOFft 8/6) to dark yellowish orange (10 YR 5/6), 

pale brown (5YR 5/2), pale red (10ft 6/2) to pale red 

purple (5ftP 6/2), and moderate orange pink (10ft 7/4) to 

moderate reddish brown (10ft 4/6). Less weathered 

rocks are medium gray (M>) to medium dark gray (N4).

The Buttermilk Falls southwest of Godfrey Ridge is 

fossiliferous, containing brachiopods, crinoid columnals, ostracodes, bryozoans, trilobites, conodonts, and 

corals.

About 25 feet (8 m) of fresh Buttermilk Falls Limestone is exposed in a 40-foot- (12-m-) long overgrown pit 

cut into the side of Stony Ridge behind a red garage, 

about 1,000 feet (305 m) southwest of the road intersection in Little Gap and on the west side of Buchwha
ONESQUETHAWAN ROCKS 23

Creek (fig. 1, loc. 8). The rocks here consist of flaggy to 

thin-bedded (beds 1 inch to 2 feet (2.5 m-0.6 m) thick) 

and unevenly bedded, medium-light-gray (M>) to 

medium-dark-gray (N4), fine-grained limestone with 

nodules of grayish-black (N2) chert several inches long. 

Brachiopods are common. A channel sample of about 9 

pounds (4 kg) of rock was digested in dilute acetic acid, 

but no conodonts or ostracodes were found; only minor 

silicified brachiopod fragments were recovered.

At the pits of the Universal Atlas Cement Co., east of 

Kunkletown (fig. 1, loc. 7), the varicolored clay becomes 

white (AT9) at depth. In these pits, the saprolite is deeper 

than 180 feet (55 m) in places. X-ray diffraction studies 

show that leaching of the Buttermilk Falls Limestone 

has removed calcite and chlorite from the fresh rock and 

altered 2M muscovite to Md polymorph (Epstein and 

Hosterman, 1969). A few thin bands of moderate-red 

(5R 4/6) to dusky-red (5.R 3/4) hematitic shale about 2 inches (5 cm) thick are found in the clay near the top.

At Saylorsburg, the contact with the underlying 

Palmerton Sandstone is covered, but it is probably 

sharp, as it is in the pits of the Universal Atlas Cement 

Co., east of Kunkletown, and along the Pennsylvania 

Turnpike. Both the Buttermilk Falls and the overlying 

Marcellus are deeply weathered at Saylorsburg, and the 

upper contact is placed at the top of the bed containing 

the last chert going upsection (measured section 4). At 

the pits near Kunkletown, the Buttermilk Falls clays 

are in sharp contact with at least 5 feet (1.5 m) of 

grayish-black (N2) carbonaceous fissile shale of the 

overlying Union Springs Shale Member of the 

Marcellus Shale (Epstein and Hosterman, 1969, fig. 6). 

A similar sharp contact is exposed along the Pennsylvania Turnpike where the basal 1.5 feet (0.5 m) of 

dark-gray (N3) to medium-dark-gray (N4) shale of the 

Marcellus contains abundant coarse mica and pyrite 

grains of its Tioga Ash Bed (see Sevon, in Epstein and 

others, 1974, p. 132), marking the top of the Onesquethawan Stage (Dennison and Textoris, 1966). Three to 

five beds within the Buttermilk Falls contain similar 

mica flakes. These may be volcanic ash similar to the 

Tioga These pale-yellowish-orange (10 YK 8/6) to 

grayish-orange (IQYR 7/4) shale beds are 1 inch (2.5 cm) 

to 1.1 feet (34 cm) thick and lie 16 to 28 feet (5-8.5 m) 

above the base of the Buttermilk Falls along the Turnpike exposure.

In the clay pits near Kunkletown, no ash bed was 

seen in the 10-foot (3-m) interval straddling the 

Marcellus-Buttermilk Falls contact. The rocks at the 

contact are replete with slickensides, so it is probable 

that the Tioga here is absent due to faulting.

About 5 feet (1.5 m) above the base of the Buttermilk 

Falls in the Turnpike roadcut are two beds of brownishgray (5YR 4/1) to dusky-red (5.R 3/2) siderite separated

by a dark-gray (N3) hematitic siltstone. This is the Hazard paint ore that has been described by many workers, 

including Agthe and Dyan (1910), who traced it from 

Little Gap to Germans, a distance of more than 12 miles 

(19 km). The Hazard "ironstone" is 1.6 feet (0.5 m) thick 

along the Pennsylvania Turnpike (measured section 5), 

a figure in agreement with all previous workers, except 

Willard (1967) who reported 6 to 7 feet (2 m). It was 

reportedly 3.7 feet (1.1 m) thick in the abandoned mine 

at Hazard (Hill, 1887), but Miller (1911, p. 57) was 

unable to verify this figure. Sevon (1970, in Epstein and 

others, 1974) believed that the distribution of the 

Hazard could be determined by the extent of iron staining in the underlying Palmerton Sandstone. The iron 

was leached from the Hazard and precipitated in the 

Palmerton. However, hematite staining is also common 

beyond the limits of the Hazard, such as at Saylorsburg. 

The iron probably was leached from the overlying Buttermilk Falls at this locality.

The Hazard contains abundant brachiopods, trilobites, crinoids, and bryozoa and less common corals, 

ostracodes, and mollusks (Willard and Whitcomb, 

1938).

Below the Hazard paint ore along the east side of the 

Pennsylvania Turnpike, is about 5 feet (1.5 m) of weathered light-gray (N7) to medium-dark-gray (N4), grayishorange (10YK 7/4) to moderate-yellowish-brown (IQYR 

5/4) clay, shale, and minor siltstone containing scattered 

coarse and medium sand grains similar to the sand 

grains in the basal part of the Foxtown Member of the 

Buttermilk Falls Limestone at the southwest end of the 

Godfrey Ridge. Lithologic details of this unit and the 

others in the Buttermilk Falls are given by Sevon (in 

Epstein and others, 1974, p. 403-405).

On the west side of the turnpike at road level, there 

are several fresh limestone beds below the Hazard that 

contain the following conodonts (identified by A. G. 

Epstein, U.S. Geological Survey): (1) Icriodus cf. /. 

struvei Weddige, (2) /. sp. indet., (3) Polygnathus 

angusticostatus Wittekindt, and (4) P. angusticostatus 

trans. to P. robusticostatus Bischoff and Ziegler. 

Because these rocks lie below the Tioga Ash Bed, the 

age can be narrowed to the Polygnathus costatus 

costatus zone (early Middle Devonian), and the rocks 

correlated with the upper half of the Moorehouse 

Member of the Onondaga Limestone of New York.

There are no natural outcrops of the Buttermilk Falls 

Limestone southwest of the Wisconsinan terminal moraine. It is exposed only in several clay and sand pits and 

highway cuts. In the Saylorsburg area, the position of 

the Buttermilk Falls is marked by many collapsed drifts 

that were sites for underground access to the clays (Peck, 

1922). Elsewhere, it generally lies on the northern slopes 

of the ridges buried by debris shed from units higher up, 

generally from the Palmerton Sandstone.
24 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

REGIONAL CORRELATIONS

Rocks of Onesquethawan age extend northeast 

through New Jersey into southeastern New York with 

the same general lithologic characteristics as those in 

Godfrey Ridge (for example, Helpers, 1950b; Johnson 

and Southard, 1962; Oliver, 1962, Rickard, 1964; and 

Oliver and others, 1967). However, stratigraphic details 

have not been determined, and the three members of the 

Buttermilk Falls Limestone have not been mapped 

beyond Buttermilk Falls, Pa Oliver (1962) and Inners 

(1975) recognized that the crinoid columnals in the lower 

half of the Foxtown Member are similar and probably 

are part of a zone continuous with those in the basal 

part of the Edgecliff Member of the Onondaga Limestone of New York.

Equivalents of the Palmerton Sandstone are not 

found in the main outcrop belt between Godfrey Ridge 

and Port Jervis, N.Y. However, a similar sandstone is 

found in the Green Pond Mountain area of northern 

New Jersey and southeastern New York, about 40 miles 

(64 km) northeast of Buttermilk Falls and about 22 

miles (35 km) southeast of the main outcrop belt. It was 

named the Kanouse Sandstone by Spencer and others 

(1908), who believed that it is a shoreward equivalent of 

the Onondaga Limestone in the main outcrop belt, a 

fact corroborated by Kindle and Eidman (1955), although Willard (1937) thought that it correlated with 

the Esopus of the Delaware Valley. In central New 

York, much thinner sandstone is found at the base of 

the Edgecliff Member of the Onondaga Limestone 

(Oliver, 1954).

The Palmerton Sandstone does not appear to extend 

very far northward in the subsurface from its type area. 

The Phillips Petroleum No. 1 Graver Estate well was 

drilled 3.5 miles (5.6 km) north of Palmerton in an apparently faulted sequence of rock. It did not penetrate 

any rocks that could be interpreted to be the Palmerton 

Sandstone (Epstein and others, 1974, p. 459). The absence of the Palmerton is similar to the rapid disappearance of the sandstone between the northeast end of 

Cherry Ridge and Godfrey Ridge near Saylorsburg. The 

Palmerton, therefore, may be interpreted as a linear 

sand body that was probably never more than a few 

miles wide.

Stratigraphic relations of Upper Silurian through 

lower Middle Devonian rocks southwest of the 

Lehighton quadrangle are not well known because of 

very poor exposures, limited paleontologic data, and 

abrupt lithic changes. The entire sequence becomes 

thinner and more clastic as an ancient low-lying positive 

area is approached about 35 miles (56 km) southwest of 

the Lehighton quadrangle (Epstein and others, 1974, 

p. 111). The area was named the "Harrisburg axis" by

Ulrich (1911) and Willard (1941) and termed the 

"Auburn Promontory" by Swartz (in Willard and 

others, 1939). Wood and others (1969) delineated this 

area of stratigraphic thinning in several isopach maps. 

Rocks of Onesquethawan age thin to about 100 feet 

(30 m) at Andreas, Pa., 7 miles (11 km) southwest of the 

Lehigh River, and are absent about 46 miles (74 km) farther southwest (Berg and others, 1980).

The continuation and identity of Onesquethawan 

rocks southwest of the Lehigh River is uncertain. For 

example, along the Pennsylvania Turnpike, Willard (in 

Willard and others, 1939) subdivided the rocks above 

the Hazard paint ore and below the Marcellus into the 

Buttermilk Falls Limestone and the underlying Selinsgrove Limestone. The Buttermilk Falls disappears 

westward with the loss of chert and was included in the 

Selinsgrove of central Pennsylvania. Willard equated 

the Hazard and the underlying Esopus (SchoharieEsopus of this report) with the Needmore Shale of central Pennsylvania. Willard (1957) later placed all the 

rocks above the Hazard along the Turnpike in the 

Selinsgrove Limestone (see fig. 2). Seven (in Epstein and 

others, 1974) believed that the 5 feet (1.5 m) of shaly 

beds below the Hazard may correspond to the Needmore Shale of the Susquehanna River area. Thus, correlation of Onesquethawan rocks west of the area of this 

report has been quite speculative.

There are only two good exposures of these rocks between the Lehigh and Schuylkill Rivers. One is in an active quarry 0.5 mile (0.8 km) southeast of Andreas, Pa., 

2.3 miles (3.7 km) southwest of the southwest corner of 

the Lehighton quadrangle. The other is 20 miles (32 km) 

southwest of Andreas in an abandoned quarry about 1 

mile (1.6 km) northeast of Schuylkill Haven, Pa.

At Andreas, weathered limestone, called Onondaga 

by Swartz and Swartz (1941) and by Seven (1968), and 

the Palmerton Sandstone are exposed. Near the bottom 

of the quarry, the Bossardville Limestone, which is 

about 70 feet (21 m) thick, underlies about 60 feet (18 m) 

of argillaceous and sandy limestone and calcareous 

shale and sandstone of the Decker Formation. Both of 

these units are Late Silurian in age (Swartz and Swartz, 

1941; Epstein and Epstein, 1967, 1969). These are overlain by 86 feet (26 m) of red shale (termed the Andreas 

red beds by Swartz and Swartz (1941) and tentatively 

assigned a Keyser (Decker) age) and sandstone. These 

red beds are interbedded with light-gray (N7) crossbedded sandstone that weathers grayish orange (10 YR 

7/4). The age of the red beds and gray sandstones remains speculative. They may be Decker equivalents (uppermost Silurian) or facies of the Stormville Member of 

the Coeymans Formation (Lower Devonian, on the basis 

of inferred stratigraphic position as determined by 

mapping (Epstein and Epstein, 1967, p. 16, 17; Epstein
ENVIRONMENTS OF DEPOSITION 25

and others, 1974, p. 84-87). Sevon (1968, p. 191) believed that the Oriskany is represented by nonred sandstones interbedded with the red beds that he called New 

Scotland. These uncertainties as to the age of these 

sandstones have an important bearing on identifications at Schuylkill Haven.

About 1 mile (1.6 km) southwest of Andreas, Swartz 

and Swartz (1941, p. 1145) and Sevon (1968) reported 

that the Oriskany is missing, on the basis of interpretation of float. The only difference is that Sevon (1968, 

and oral commun., 1981) noted that 27 feet (8 m) of 

Esopus and Schoharie intervened between cherts of the 

New Scotland Formation and the Palmerton Sandstone 

and Swartz and Swartz (1941) did not recognize any 

Esopus and Schoharie (their Bowmanstown Chert).

At Schuylkill Haven, the section consists of 44 feet 

(13 m) of nodular limestone and calcareous shale, siltstone, and sandstone, referred to as the Keyser 

Limestone by Swartz and Swartz (1941, p. 1134) and 

equivalent to the Decker Formation to the northeast. 

Most of these beds contain typical Late Silurian fossils. 

At the top of this sequence are about 13 feet (4 m) of 

interbedded, laminated to slabby (beds up to about 10 

inches (25 cm) thick), pale-olive (10 Y 6/2) to light-olivegray (5Y 6/1) and greenish-gray (5GY 6/1) fissile shale 

and shaly siltstone and quartzose blocky medium-lightgray (M>) and light-olive-gray (5Y 6/1) very fine grained 

sandstone. No fossils were seen in these upper beds. 

Sevon (1968) tentatively assigned the lower rocks to the 

Schoharie and Esopus Formations and the upper 13 feet 

(4 m) to the New Scotland Formation, but this assignment is doubtful. The uppermost sandstones and shales 

may correlate with the Stormville Member of the 

Coeymans or the Decker Formation.

Next in succession at Schuykill Haven is a 4- to 

5-foot- (1.2- to 1.5-m-) thick bed of quartz-pebble conglomerate with pebbles 0.25 inch to 1 inch (0.6-2.5 cm) 

long. This bed lies abruptly on the green and gray beds, 

possibly unconformably or in fault contact. No fossils 

were seen. Cleaves (in Willard and others, 1939, p. 129), 

however, reported an Oriskany fauna from an outcrop 

on the east side of the quarry, presently not exposed, 

and in loose blocks. He believed that the Palmerton 

Sandstone is absent in the quarry, as did Willard (in 

Willard and others, 1939, p. 153). Swartz and Swartz 

(1941, p. 1134) also identified these rocks as the 

Oriskany Sandstone. Sevon (1968), on the other hand, 

identified the sandstone as the Palmerton, on the basis 

of textural comparisons of the Palmerton with the 

Oriskany. Wood (1973) mapped a conglomeratic sandstone in the bottom of the Selinsgrove Limestone, suggesting that it is the Palmerton Sandstone.

Thus, the identification of this sandstone bed at 

Schuylkill Haven is open to considerable question.

Unless the Oriskany fauna can be confirmed, this bed 

could be Palmerton, Oriskany, or even Stormville. An 

added complication is that Cleaves (in Willard and 

others, 1939) thought that the Oriskany is more than 40 

feet (12 m) thick here. Faulting in the area, cutting out 

the Oriskany in the quarry, is quite possible.

The conglomeratic sandstone is overlain next by noncherty medium-gray (A/5) and medium-dark-gray (A/4) 

fossiliferous shale and limestone. This was named the 

Needmore Shale by Cleaves (in Willard and others, 

1939, p. 129), the Selinsgrove Limestone by Willard (in 

Willard and others, 1939, p. 153) and Wood (1973), and 

the Onondaga Limestone or Formation by Swartz and 

Swartz (1941), Sevon (1968), and Inners (1975).

The discussion above demonstrates the need for further study of stratigraphic details between the Lehigh 

River and the well-known Onesquethawan interval in 

central Pennsylvania in the Susquehanna River area

ENVIRONMENTS OF DEPOSITION

The abrupt contact between the Esopus Formation at 

the base of Onesquethawan rocks and the underlying 

Ridgeley Sandstone of the Oriskany Group is believed 

to be an unconformity (Willard, in Willard and others, 

1939, p. 154; Epstein and Epstein, 1967, p. 18), reflecting a period of regional emergence. The locus of subsequent Onesquethawan deposition was in northeasternmost Pennsylvania and southeastern New York, where 

more than 800 feet (240 m) of sediments was deposited. 

Nearly pure carbonate rocks are in the north, and they 

become more clastic southwards (Oliver and others, 

1967, p. 1012-1013). In the area of this report, the units 

thin and become more clastic to the southwest along 

strike (fig. 3).

Onesquethawan rocks are believed to represent a 

deep- to shallow-neritic regressive sequence that followed shallow marine (beach or bar) deposition of the 

underlying Ridgeley Sandstone. The Esopus Formation 

is interpreted to be a deep neritic deposit because it is 

widespread and fairly uniform in its lithic characteristics, it does not contain abundant shell debris, and it 

contains the trace fossil Taonurus (fig. 6), which represents the sublittoral to bathyal Zoophycus facies of 

Seilacher (1967). Lower Schoharie beds also contain 

Taonurus, as well as hexactinellid sponge spicules, 

which also suggests a deepwater environment (Prof. J. 

Keith Rigby, Jr., written commun., 1981). According to 

Shrock and Twenhofel (1957, p. 83), the Hexactinellida 

lived at depths between 300 to 16,000 feet (100- 

> 5,000 m). Reid (1968) similarly indicated that Hexactinellida are rare above 660 feet (200 m). Taonurus 

disappears upwards, and vertical burrows become dominant in the middle part of the Schoharie Formation.
26 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

Seilacher (1967, p. 421) noted that the transition from 

horizontal to vertical burrows reflects transition from 

sediment feeding in the deeper zone, where food settles 

in quieter water, to suspension feeding in the shallower, 

more agitated zone. This indicates that gradual transition from deep-neritic to shallower deposits proceeded 

through Schoharie time. Basin shallowing continued 

from late Schoharie into Buttermilk Falls time and produced depths within the photic zone that contained 

warm, well-oxygenated, and gently circulating water. 

These neritic conditions are indicated by the upward 

increase in diverse marine fauna (including corals), vertical burrows, and abundance of limestone in the upper 

part of the Schoharie and the Buttermilk Falls 

Limestone.

Interpretation of the bathymetry of the Esopus and 

Schoharie Formations rests to a large part on inferences 

drawn from the occurrence of Taonurus. A short discussion of this trace fossil therefore is appropriate.

In cross section, Taonurus consists of alternating 

light and dark meniscate bands in laminae 0.1 to 0.3 

inch (2-8 mm) thick (fig. 16A, B). The laminae generally 

parallel bedding, but some are crosscutting and may be 

inclined nearly 30° (fig. 16C). The sediments in which 

Taonurus is found are mostly fine to coarse siltstone. 

The darker bands contain more muscovite and chlorite 

and less quartz than the lighter bands and may contain 

slightly more carbonaceous matter. There does not appear to be differential sorting of the quartz in the two 

types of bands.

A large literature on ichnology (the study of trace 

fossils) exists, but total agreement on the interpretation 

of Zoophycus, the general group to which Taonurus 

belongs, is lacking. Most investigators have concluded 

that ichnofossils are sedimentary structures resulting 

from organic activity and reflect the ecological environment of the producing animals regardless of the 

animals' morphology or geologic age. The structures in 

the Zoophycus fades were produced by hemisessile 

deposit feeders, generally below wave base in areas free 

of turbidite sedimentation (that is, quiet offshore waters 

in deep-shelf and bathyal areas), although the fades is 

gradational into shallower and deeper zones (Crimes, 

1973; Frey, 1975; Seilacher, 1964, 1967, 1978). Some 

workers have noted that Taonurus occurs in sediments 

deposited above wave base in protected areas (Crimes, 

1973; Hallam, 1975; Kennedy, 1975; Osgood and 

Szmuc, 1972). As noted by Seilacher (1978), the 

examples of Taonurus in shallower deposits do not 

invalidate the use of trace fossil assemblages in environmental analysis, especially when other paleontological and sedimentological criteria are used.

At the other end of the interpretive spectrum, Plicka 

(1968) believed that Zoophycus are prostomia of marine 

worms. Osgood (1975) disagreed, partly because of the

interpenetration of the structures (see fig. 16C). Similarly, Sarle (1906) believed that Taonurus could not be a 

body fossil. Osgood also disagreed with the interpretation of Loring and Wang (1971) that Taonurus is a 

marine plant.

Goldring and Flower (1942) suggested that Taonurus 

represents deposition in mud flats "in which sandy 

sediments were subject to constant reworking by 

organisms during their extremely slow accumulation." 

However, I know of no reports of Taonurus forming in 

recent tidal-flat sediments or formed in proven ancient 

tidal-flat sediments.

Another dissenting opinion is given by Sevon (in Epstein and others, 1974, p. 118-119) who believed that 

these structures are overturned ripples formed by currents that alternated in direction on a tidal flat. 

However, if these structures are indeed ripples, most 

overlying laminae would indicate a direction of current 

flow that is opposite to the direction that would be 

necessary to overturn the underlying ripple (see fig. 

16A, B). In plan view, as seen on bedding surfaces, 

which are rarely exposed in eastern Pennsylvania 

because of the intense development of rock cleavage, 

Taonurus appears as curved alternating light and dark 

bands in masses up to a few feet in diameter (see Chamberlain, 1978, p. 159, fig. 115) with tiny appendages (fig. 

16Z>), quite unlike ripple marks generated on a tidal flat. 

Moreover, there are many published photographs of 

Zoophycus from a wide range of geologic ages that are 

similar to Taonurus seen in the Esopus and Schoharie of 

eastern Pennsylvania (Chamberlain, 1978, p. 158; 

Ekdale, 1977, p. 171, 173; Kennedy, 1975, p. 386; 

Seilacher, 1967, p. 423).

In summary, the available evidence and comparisons 

with published data suggest that the trace fossil 

Taonurus is a feeding burrow of an animal that lived in a 

marine environment below wave base.

The Palmerton Sandstone, which is the southwestward lateral equivalent of the upper part of the 

Schoharie Formation and the lower part of the Buttermilk Falls Limestone (fig. 3), probably accumulated at 

depths similar to or somewhat shallower than those of 

its correlatives but was close to a source of coarse 

clastic supply. The formation is massive and generally 

lacks sedimentary structures except for channeled lower 

contacts in basal beds. This does not help in interpretation of the environment of deposition. The Palmerton is 

definitely marine, as indicated by minor crinoid and coral debris (probably derived from the nearby Buttermilk 

Falls carbonate terrane). It may be a beach or barrierbar nearshore deposit. The quartz types in the Palmerton suggest a source area consisting of sandstone and 

quartzite, quartz veins, chert-bearing sediments, and 

possibly granitic rocks.

The unique iron-rich rocks of the Hazard paint ore
ENVIRONMENTS OF DEPOSITION 27

D

FIGURE 16. The trace fossil Taonurus in the Esopus and Schoharie 

Formations, northeastern Pennsylvania A, Polished slab showing 

cross section of completely bioturbated siltstone, from roadcut 

southeast of Bowmanstown (fig. 1, loc. 10). Direction of meniscate 

light and dark bands alternates in each overlying laminae. B, 

Negative print of acetate peel showing rapid lateral termination of 

meniscate laminae. Stratigraphic top is up. Lower half of Schoharie 

Formation from roadcut along U.S. 209 near Buttermilk Falls (fig. 

1, loc. 1). C, Negative print of thin section showing crosscutting

burrows in coarse quartz-muscovite-chlorite siltstone of the Esopus 

Formation in Godfrey Ridge, 650 feet (198 m) southwest of the 

WVPO radio tower, near Stroudsburg. Stratigraphic top is to the 

left. Horizontal lines are rock cleavage. White markings are orientation scratches on thin section. D, Polished slab cut parallel to bedding from same locality as figure 16A The burrows are curved, 

and the bands are digitated. Later burrowing has altered earlier 

structures in several places.
28 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

suggested unusual conditions for iron accumulation to 

Sevon (in Epstein and others, 1974, p. 119, 130-131).

Onesquethawan time ended with the regional deposition of a volcanic ash, the Tioga Ash Bed. The volcanic 

center was in the Piedmont of central Virginia (Dennison, 1969). This was followed by sublittoral deposition 

below wave base in a reducing environment represented 

by the carbonaceous, pyritic, sparsely fossiliferous 

laminated shales of the Marcellus Shale.

MEASURED SECTIONS

Section 1

Esopus and Schoharie Formations and Foxtown Member of the Buttermilk Falls Limestone in roadcut along U.S. Route 209 near Buttermilk Falls, East Stroudsburg quadrangle, Pennsylvania Beds 

dip gently to the southwest. Type locality of the Buttermilk Falls 

Limestone. Locality 1, figure 1.

Buttermilk Falls Limestone (part): Thickness 

Foxtown Member (part): (Feet) (Meters) 

7. Limestone, silty; medium-gray (M>); weathers medium light gray (M5) to light gray 

(Nl) and olive gray (5Y 5/1) to yellowish 

gray (5Y 8/1); fine- to medium-grained, 

with some coarser grains as much as 

2mm long; evenly to unevenly bedded; 

thin-bedded (beds range from 1 in. to 1 ft 

in thickness), with brachiopods and crinoid columnals that are as much as 1 in. in 

diameter. Lesser interbedded calcareous 

shale is medium dark gray (N4); weathers 

medium gray (M>); and is in thin lenses, 

laminae, and beds as much as 2 in. thick; 

burrow mottled. Irregular dark-gray (N3) 

chert lenses and pods as much as 5 in. long 

are throughout and make up about 5 percent of unit near base. Chert replaces 

limestone and also forms a halo around 

more calcareous segregations. Some chert 

contains fossils and burrows. Basal contact abrupt 25.0 7.6

Incomplete thickness of Foxtown 

Member of the Buttermilk Falls Limestone 25.0 7.6

Schoharie Formation:

6. Siltstone, dark-gray (N3) to medium-darkgray (A/4); weathers medium dark gray 

(N4) to medium gray (M>) and light olive 

gray (5F 6/1); calcareous; massive; evenly 

bedded; laminated. Contains scattered 

dark-gray (N3) chert nodules and lenses as 

much as 2 in. thick in lower half and more 

abundant chert and limestone in upper 

half of unit. Chert makes up less than 5 

percent of basal part of unit. Upper 15 ft 

contains as much as 40 percent chert, enclosing irregular lenses of dark-gray (N3) 

to grayish-black (N2) fossiliferous (brachThickness

(Feet) (Meters)

iopods), irregularly bedded, shaly siltstone. Lowest bed contains a 2-in.-thick 

grayish black chert lens that is about 3 ft 

long and about 4 in. above base; chert is 

more abundant above 31 ft above base. 

Above 51 ft above base, beds become sandy (fine-grained sandy siltstone), more 

massive and blocky (beds as much as 6 ft 

thick), and cleavage is poorly developed. 

More calcareous beds weather lighter 

gray than silty beds. Irregular lenses, 

beds, and pods of more calcareous siltstone slightly burrow mottled with vertical shale-filled burrows approximately 

0.5 in. in diameter and 1 to 2 in. long. More 

extensively burrowed and less laminated 

toward top of unit. Contains scattered 

shale chips that are inclined about 45° and 

are as much as 2 in. long 66.0 20.1

5. Siltstone, medium-dark-gray (Af4); weathers 

medium dark gray (N4) to medium gray 

(M>); calcareous; evenly bedded; thinbedded; beds range from about 4 to 16 in. 

thick; fossiliferous; moderate cleavage 

development 7.0 2.1

4. Siltstone, calcareous; dark-gray (N3) to 

medium-dark-gray (N4); weathers medium 

dark gray (N4) to medium gray (M>) and 

light olive gray (5Y 6/1) and grayish 

orange (10 YE 7/4); thin- to thick-bedded 

(beds range from a few in. to as much as 3 

ft thick); laminated, with minor interbedded calcareous shaly siltstone; fossiliferous; more evenly bedded and laminated 

and more calcareous toward top where 

unit contains coarser grained siltstone. 

Slightly burrow mottled toward top; most 

burrows are horizontal. Slightly pyritic 

toward base. No chert. Abundant Taonurus caudigaM. Slightly pyritic toward base. 

Cleavage not well developed, except in 

basal 20 ft. Contact with Esopus is gradational and placed with some question at 

the base of the first massive siltstone going upsection. Schoharie more resonant 

when hit with a hammer as compared to 

the muted sound of the Esopus 30.0 9.2

Thickness of Schoharie Formation 103.0 31.4

Esopus Formation (part):

3. Siltstone, shaly; dark-gray (N3); weathers 

medium gray (N4) to dark gray (N3) and 

light olive gray (5Y 6/1); iron stained dark 

yellowish orange (10 YR 6/6) to moderate 

yellowish brown (10 YR 5/4); pyritic; laminated; thin- to very thick bedded (beds 

range from 4 in. to 7 ft thick); locally calcareous; abundant Taonurus caudigaM. 

Weathers into platy fragments more readily than Schoharie 11.0 3.4 

2. Covered 26.0 7.9 

1. Siltstone, similar to unit 3 40.0 12.2

Incomplete thickness of Esopus Formation 77.0 23.5
MEASURED SECTIONS 29

Section 2

Generalized description of the Foxtown and McMichael Members of 

the Buttermilk Falls Limestone, Esopus Formation, and parts of 

the Schoharie Formation and Stroudsburg Member of the Buttermilk Falls Limestone in abandoned quarry 100 ft (30 m) south of 

the intersection of U.S. 209 and Interstate 80, 1.5 mi (2.4 km) east 

of East Stroudsburg, and 1,000 ft (305 m) southwest of the quarry 

along bluffs near the Lackawanna and Western Railroad, Stroudsburg quadrangle. The Buttermilk Falls is exposed in the quarry in 

an overturned syncline, and the Esopus and Schoharie are exposed 

in the overturned limb of that fold in the bluffs. Locality 3, figure 1.

Thickness

Buttermilk Falls Limestone (part): (Feet) (Meters) 

Stroudsburg Member (part):

5. Limestone, argillaceous, medium-gray (Mi) 

to medium-dark-gray (AT4); weathers medium gray (Mi) to light olive gray (5Y 6/1); 

fossiliferous; thin-bedded (beds range 

from 4 in. to 1 ft in thickness); with darkgray (N3) chert nodules several in. long 15.0 4.6

Incomplete thickness of the Stroudsburg Member of the Buttermilk Falls 

Limestone 15.0 4.6

McMichael Member:

4. Shale, calcareous; medium-gray (Mi); weathers light olive gray (5Y 6/1) to medium 

gray (Mi) and grayish orange (10YR 7/4); 

thin-bedded (beds 2 to 8 in. thick); with 

lenses of medium-light-gray (AT6) fossiliferous limestone 41.7 12.7

Thickness of McMichael Member of the 

Buttermilk Falls Limestone 41.7 12.7

Foxtown Member

3. Siltstone, calcareous; medium-dark-gray 

(AT4) alternating with medium-gray (Mi) 

argillaceous limestone; weathers medium 

gray (Mi) to light olive gray (5Y 6/1) and 

grayish orange (IQYR 7/4); irregularly 

bedded; thin-bedded (beds range between 

2 and 10 in. in thickness); fossiliferous 

(brachiopods and abundant crinoid columnals up to 1 in. in diameter in lower 45 ft) - 80.0

Thickness of Foxtown Member of the

24.4

Buttermilk Falls Limestone 80.0 24.4

Incomplete thickness of Buttermilk 

Falls Limestone 136.7 41.7

Schoharie Formation:

2. Siltstone, partly calcareous; dark-gray (AT3); 

generally massive; prominent cleavage 

not as well developed as in underlying 

Esopus Formation. Contact with Esopus 

gradational through about 20 ft of interbedded siltstone and silty shale. Contact 

placed at first massive siltstone bed going 

upsection.

Thickness from construction of cross 

section 100.0

Approximate thickness of Schoharie 

Formation 100.0

30.5

30.5

Thickness

Esopus Formation: (Feet> (Meters) 

1. Siltstone, generally noncalcareous except for 

beds between 7 to 9 ft above base and 

some beds between 104 to 181 ft above 

base; dark-gray (AT3); weathers medium 

dark gray (AT4) and is iron stained grayish 

orange (IQYR 7/4) to moderate brown 

(IQYR 5/4); laminated; generally massive 

(beds range from 2 in. to more than 6 ft 

thick); bedding generally not distinct 

below 104 ft; abundant Taonurus caudagatti; lower 7 ft covered; contact with 

underlying Ridgeley Sandstone of the 

Oriskany Group covered 181.0 55.2

Thickness of Esopus Formation 181.0 55.2

Section 3

Buttermilk Falls Limestone and part of the Schoharie Formation in 

railroad cut of the Erie-Lackawanna Railroad, 1 mi south of the 

East Stroudsburg Post Office, Stroudsburg quadrangle. The 

center of the cut is in the Schoharie Formation and in the crest of 

an overturned anticline. The Buttermilk Falls Limestone is in overturned beds to the north that dip as much as 55° to the southeast. 

Locality 4, figure 1. 

Buttermilk Falls Limestone: 

Stroudsburg Member

6. Limestone, medium-dark-gray (AT4); weathers medium light gray (M5) to light gray 

(AT7); fine- to medium-grained; fossiliferous; lenticular and irregularly interbedded 

with about equal amounts of grayishblack (AT2) to dark-gray (N3) chert. Generally thin bedded (beds between 2 in. and 

1 ft thick). The top of the Tioga Ash Bed is 

27 ft below the top of the unit. It is 10 in. 

to 1 ft thick and consists of light-olivegray (5Y 6/1) to dark-gray (AT4) tuffaceous 

siltstone to very fine grained sandstone 

that weathers medium light gray (A/6) and 

moderate yellowish brown (IQYR 5/4). Upper 15 ft contains three beds that are 3 to 

6 in. thick of medium-gray (Mi) to 

medium-light-gray (M5), light-gray- (AT7) 

weathering, medium- to very coarse 

grained limestone with abundant brachiopod debris. Contact with overlying 

Union Springs Shale Member of the Marcellus Shale not exposed but probably 

near top of measured unit 90.0 27.4 

5. Shale, calcareous; silty; medium-gray (Mi); 

with some medium-gray (Mi) to mediumlight-gray (AT6), fine- to medium-grained 

limestone pods as much as 2 in. in diameter that weather light gray (AT7) 3.0 0.9 

4. Limestone, locally argillaceous and fossiliferous; medium-gray (Mi) to medium-darkgray (AT4), weathers light gray (AT7) to medium light gray (AT6); fine- to mediumgrained; thin bedded with irregular beds; 

lenses and pods 1 in. to 1 ft thick; and 

dark-gray (AT3) to grayish-black (N2) chert 

in irregular pods, lenses, and discontinuous beds 0.25 to 8 in. thick 56.0 17.1
30 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

Thickness 

(Feet) (Meters)

Thickness of Stroudsburg Member of 

the Buttermilk Falls Limestone 149.0 45.4

McMichael Member:

3. Shale, calcareous; partly silty; medium-gray 

(N5) to medium-dark-gray (N4); weathers 

medium gray (N5); evenly bedded to lenticular; fossiliferous; thin-bedded (beds 2 

in. to 1 ft thick); interbedded with 

medium-gray (N5), fine-grained limestone 

in beds, lenses, and nodules 1 to 3 in. 

thick. Limestone contains ostracodes and 

brachiopod and crinoid debris. Contact 

with overlying Stroudsburg Member gradational and marked by upward appearance of chert and disappearance of argillaceous beds ___ 

41.0 12.5 

Thickness of McMichael Member 41.0 12.5

Foxtown Member

2. Limestone, medium-gray (N5) to mediumdark-gray (N4); weathers light gray (NT) 

to medium light gray (M5); fine- to very 

coarse grained; irregularly bedded to lenticular; generally thin-bedded (beds 1 in. 

to 2 ft thick); interbedded with mediumdark-gray (N4), calcareous, evenly bedded 

shale and siltstone in beds 1 in. to 1 ft 

thick and grayish-black (N2) to dark-gray 

(N3) chert. Chert in lower half in irregular 

nodules 0.5 to 6 in. long. Chert becomes 

more abundant in upper half where it 

makes up more than 50 percent of unit 

and is interbedded with calcareous shale 

and siltstone 1 to 2 in. thick and limestone 

pods 2 to 6 in. in diameter. Large crinoid 

columnals with cross section diameters to 

1 in. are conspicuous in lower half. Abundant ostracodes. Base marked by 1-ftthick, medium-gray (N5), light-gray- (NT) 

weathering, medium- to very coarse 

grained limestone in abrupt contact with 

underlying Schoharie Formation. Contact 

with overlying McMichael Member transitional through 4-ft interval 82.0

Thickness of Foxtown Member 82.0

Thickness of Buttermilk Falls Limestone 272.0

25.0

25.0

82.9

17.7

Schoharie Formation (part):

1. Siltstone, sandy to argillaceous; calcareous 

to noncalcareous; medium-gray (N5) to 

medium-dark-gray (N4); in beds as much 

as 5 ft thick. Becomes sandier towards 

top. Base not exposed 58.0 __

Incomplete thickness of Schoharie Formation 58.0 17.7

Section 4

Schoharie Formation, Palmerton Sandstone, and parts of the Esopus 

and Schoharie Formations and Marcellus Shale in roadcut through

Cherry Ridge along Pa State Route 33 near Saylorsburg, Saylorsburg quadrangle. Beds are overturned and dip as much as 30° to 

the southeast. Many units are deeply weathered to saprolite. Measured during road construction in 1962. Locality 6, figure 1.

Thickness 

Marcellus Shale (part): (Feet) (Meters)

27. Shale, medium-gray (M>); weathers dark yellowish gray (5Y 6/2) to grayish orange 

(10 YR 7/4). Upper contact covered 10.0 3.1

26. Shale, medium-gray (N5); weathered partly 

to clay; weathers pale yellowish orange 

(10 YR 8/6) to dark yellowish orange (10 YR 

6/6), pale red purple (5RP 6/2), moderate 

reddish brown (10ft 4/6), and light gray 

(#7). 

Thickness approximate 50.0 15.2

25. Shale, silty, and clay; weathers grayish 

orange (10 YR 7/4) to moderate reddish 

brown (10ft 4/6); trilobite fragments 45.0 13.7

Incomplete thickness of Marcellus

Shale 105.0 32.0

Buttermilk Falls Limestone:

24. Clay, silty, with some fine-grained sand; 

pale-red-purple (5ftP 6/2) and very light 

gray (N8), with light-gray (NT) and mottled 

reddish chert; few crinoid columnals; last 

chert going upsection 17.0 5.2

23. Clay, argillaceous; limonitic and hematitic; 

very dark yellowish-orange (lOYft 5/6) to 

dark-yellowish-orange (107ft 6/6) and moderate-reddish-brown (10ft 4/6) to pale-brown 

(57ft 5/2); with iron-stained light-gray (NT) 

to medium-gray (N5) chert; scattered 

brachiopods. Lower half covered by concrete abutment at overpass of SaylorsburgBossardsville road 35.0 10.7

22. Clay, silty; moderate-pinkish-red (5ft 6/4), 

light-gray (NT), and dark-yellowish-orange 

(107ft 6/6); with minor chert that weathers very dusky red (5ft 2/6) and very light 

gray (N8) to medium gray (N5). Some 

brachiopods 25.0 7.6

21. Siltstone, shaly; clayey; mottled yellowishorange (lOYK 7/6) and pale-red-purple 

(5ftP 6/2); fossiliferous 3.0 0.9

20. Clay, white (JV9) to light-gray (NT) and very 

pale orange (107ft 8/2), with light-gray 

(NT) to medium-gray (N5) chert 28.0 8.5

19. Clay, medium-light-gray (M5) and yellowishorange (lOyft 7/6), with very light gray 

(N8) to medium-gray (N5) chert. Chert 

more abundant than in underlying unit 32.0 9.8

18. Clay, light-gray (NT), yellowish-gray (5Y 

8/1), yellowish-orange (107ft 7/6), and 

pale-red (5ft 6/2). Few beds 1 to 3 in. thick 

of nodular chert 25 to 45 ft above base. 

Fossiliferous (bryozoans) 58.0 17.7

17. Chert, white (W) to light-gray (NT); and 

silty to medium- to coarse-grained sandy 

white (A/9) to very light gray (NS) clay. 

Very fossiliferous in places (crinoid columnals, favositiid corals, ostracodes, and 

bryozoans). Contact with underlying Pal-
MEASURED SECTIONS 31

Thickness

_. o J . J u . u u, <Feet> (Meters> merton Sandstone covered but probably

sharp 65.0 19.8

Thickness of Buttermilk Falls Limestone 263.0 80.2

Palmerton Sandstone

16. Sandstone, slightly limonitic; medium-gray 

(N5) to very light gray (N8) and darkyellowish-orange (WYR 6/6); medium- to 

very coarse grained; with some quartz 

grains as much as 3 mm long; silica cement; thin- to thick-bedded 13.0 4.0

15. Sandstone, coarse- to very coarse grained 

and conglomeratic; quartz pebbles are 

subrounded to well rounded and as much 

as 5 mm long with rare grains as much as 

10 mm long; very light gray (N8) to lightgray (A/7), pale-yellowish-orange (10YR 

8/6) to dark-yellowish-orange (WYR 6/6); 

partly laminated; generally very thick 

bedded (some beds are more than 8 ft 

thick); a few beds of fine-grained sandstone near base 48.0 14.6

14. Sandstone, very fine to fine-grained; with 

scattered coarse sand grains; darkyellowish-orange (10 YR 6/6); with 

moderate-brown (5YR 4/4) ironstone concretions that are 1 to 2 in. in diameter 0.6 0.2

13. Sandstone, very coarse grained; ironstained; very dark reddish-brown (WR 2/4) 

to dark-yellowish-brown (10 YR 4/2); with 

lesser yellowish orange (10 YR 7/6) and 

very pale orange (WYR 8/2) siltstone and 

very fine grained sandstone. Many channeled upward-fining subunits; base irregular and disconformable; relief about 

2.7 ft 4.2 1.3

Thickness of Palmerton Sandstone 65.8 20.1

Schoharie and Esopus Formations, undivided: 

Schoharie Formation:

12. Siltstone and very fine grained sandstone 

with scattered quartz grains as much as 

3mm long; dark-yellowish-orange (10YR 

6/6) and very light gray (A/8); with darkyellowish-brown (WYR 5/2) ironstone concretions as much as 5 in. in diameter and 

ironstone beds about 0.5 in. thick. Near 

top of unit, 3-in.-thick, pale-yellowishorange (WYR 8/6) to dark-yellowishorange (WYR 6/6), very coarse grained 

sandstone bed is cut out by channeling of 

overlying unit about 10 ft above road 

level. Lower contact irregular and disconformable 2.2

11. Siltstone and medium-grained sandstone 

with scattered quartz grains as much as 

1 mm long; very light gray (A/8) to lightbrown (5YR 5/6); with light-gray (A/7) to 

medium-gray (N5) chert; sparingly fossiliferous (brachiopods) 0.6

0.7

0.2

Thickness

(Feet} (Meters) 

10. Siltstone, sandy; with scattered quartz

grains as much as 3 mm long; very light 

gray (N8) and dark-yellowish-orange 

(WYR 6/6), with light-gray (A/7) to 

medium-gray (A/5) chert nodules averaging about 1 in. in diameter 2.0 0.6

9. Siltstone, silicified, and very fine grained 

sandstone with scattered quartz grains as 

much as 2 mm long; light-gray (A/7) and 

dark-yellowish-orange (WYR 6/6); with 

light-gray (A/7) to very light gray (NS) 

chert nodules as much as 2 in. long; scattered brachiopods 1.1 0.3

8. Siltstone, sandy, shaly, silicified, to very fine 

grained sandstone with scattered quartz 

grains as much as 2 mm long and a few 

grains as much as 5 mm long; paleyellowish-orange (WYR 8/6) to darkyellowish-orange (IQYR 6/6); massive 

(beds as much as 3.5 ft thick), with a few 

shale and shaly siltstone beds 1 to 2 in. 

thick; scattered brachiopods 10.7 3.2

7. Siltstone, silicified, to very fine grained 

sandstone with scattered quartz grains as 

much as 1 mm long; very light gray (N8) 

and pale-yellowish-orange (WYR 8/6) to 

dark-yellowish-orange (WYR 6/6); burrowed 0.9 0.3

6. Siltstone, shaly; yellowish-orange (WYR

7/6) 0.6 0.2

5. Siltstone, shaly; very pale orange (WYR 

8/2) to yellowish-orange (WYR 6/6) in two 

beds 14 and 12 in. thick; fossiliferous; burrowed; with very light gray (N8) to lightgray (A/7) chert 2.2 0.7

4. Siltstone, shaly; grayish-orange (10 YR 7/4) 

to yellowish-orange (WYR 7/6); thinbedded (beds 2 in. to 1.2 ft thick); fossiliferous; with a few shale beds about 1 in. 

thick; and very light gray (N8) to mediumgray (A/5) and grayish-orange (WYR 7/4) 

chert pods, lentils, and irregular beds as 

much as 3 in. thick 8.2 2.5

3. Chert, medium-gray (A/5) to very light gray 

(A/8) and grayish-orange (WYR 7/4) to 

dark-yellowish-orange (10 YR 6/6) burrowed siltstone 0.3 0.1

2. Siltstone, shaly; very light gray (A/8), yellowish-gray (57 8/1), yellowish-orange (WYR 

7/6), and grayish-yellow (5Y 8/4), evenly bedded; thin-bedded (beds 2 in. to as much as 1 

ft thick); fossiliferous; burrowed; with small 

(less than 1 in. long) lenticular chert pods 

parallel to bedding 4.3 1.3 

Thickness of Schoharie Formation 33.1 10.1

Esopus Formation:

1. Siltstone and shaly siltstone, light-gray (A/7) 

to medium-dark-gray (A/4) on fresher surfaces; weathers shades of gray, purple, 

orange, red, and brown (light gray (A/7), 

light greenish gray (5GY 7/1), grayish red 

(5R 4/2) to blackish red (5R 2/2), and dark
32 ONESQUETHAWAN STRATIGRAPHY OF NORTHEASTERN PENNSYLVANIA

Thickness 

(Feet) (Meters)

yellowish orange (10YR 6/6)); mottled in 

places; iron-stained; color bands transect 

bedding and well-developed cleavage; 

evenly bedded; laminated and thin-bedded 

(beds range from 1 in. to 1 ft in thickness); 

lower half of unit partly slumped; lower 

contact concealed; weathers darker than 

overlying Schoharie Formation 35.0

Incomplete thickness of Esopus Formation 35.0

10.7

10.7

Incomplete thickness of Schoharie and 

Esopus Formations, undivided 68.1 20.8

Section 5

Generalized description of the Ridgeley Sandstone and part of the 

Shriver Chert of the Oriskany Group, Esopus and Schoharie Formations, Palmerton Sandstone, Buttermilk Falls Limestone (including the Hazard paint ore), and lower part of the Marcellus 

Shale (Union Springs Shale Member, including the Tioga Ash Bed, 

and part of the Stony Hollow Member) along the east bench in 

highway cut through Stone Ridge about 20 ft above the Northeast 

Extension of the Pennsylvania Turnpike, Lehighton quadrangle. 

Beds are overturned and dip 67° to 80° SE. A more detailed 

description of the units is given by Sevon (in Epstein and others, 

1974, p. 400-406). The rocks are faulted, particularly the Marcellus 

Shale (see Glaesser, in Epstein and others, 1974, p. 288), so that the 

units have different thicknesses in different parts of the cut. The 

rocks are generally deeply weathered but are fresher at lower levels 

of the cut. Locality 11, figure 1.

Marcellus Shale (part): 

Stony Hollow Member (part): 

13. Shale, calcareous; medium-dark-gray (N4) 

to dark-gray (A/3); interbedded with evenly bedded dark-gray (N3) shaly finegrained limestone in beds between 4 in. 

and 1 ft in thickness and aggregating 

about 5 ft of unit; with scattered shaly 

limestone pods about 1 ft long and 4 in. 

thick. Upper contact at top of last limestone encountered going upsection and 

gradational into calcareous shales that are 

in turn gradational into noncalcareous 

shales of the overlying Brodhead Creek 

Member of the Marcellus Shale. Lower 

contact placed at base of lowest limestone 

bed. Unit highly faulted 41.7 12.7

Incomplete thickness of Stony Hollow 

Member of the Marcellus Shale 41.7 12.7

Union Springs Shale Member: 

12. Shale, noncalcareous; dark-gray t/V3) to 

medium-dark-gray (N4); sheared, welldeveloped slaty cleavage; basal 1.5 ft contains three layers 1 to 2 in. thick with 

abundant mica and pyrite grains as much 

as 1 mm long (Tioga Ash Bed). Lower contact abrupt 29.2

Thickness of Union Springs Shale Member of the Marcellus Shale 29.2

8.9

8.9

Incomplete 

Shale -

thickness of Marcellus

70.9 21.6

Buttermilk Falls Limestone:

11. Shale, siltstone, very fine grained sandstone, and clay; deeply leached residue 

from limestone; varicolored, including 

light-gray (7V7) to medium-dark-gray (N4), 

dark-yellowish-orange (10 YR 6/6) to paleyellowish-orange (WYR 8/6) to moderategrayish-red (IOR 5/2); partly hematitic and 

fossiliferous; with about five intervals of 

dark-gray (N3) to grayish-black (N2) chert 

nodules and irregular beds between 7 and 

25 ft above base above base of unit; with 

at least three beds and possibly five beds 

of grayish-orange (10 YR 7/4) to paleyellowish-orange (10 YR 8/6) shale that are 

1 in. to 1.1 ft thick and 9 to 21 ft above 

base of unit, containing abundant biotite 

flakes (Tioga Ash?). Lower contact 

abrupt 

10. Siderite and hematitic siltstone; brownishgray (SYR 4/1) to dusky-red (5R 3/2) and 

dark-gray (N3) siltstone; in beds 0.5 to 0.6 

ft thick (Hazard paint ore). Lower contact 

abrupt 

9. Clay, shale, and minor siltstone, leached 

from limestone, with floating medium and 

coarse sand grains; light-gray (N7) to 

medium-dark-gray (N4), grayish-orange 

(10 YR 7/4) to moderate-yellowish-brown 

(WYR 5/4). Lower contact abrupt. On 

west side of the cut at road level, this interval contains nodular beds, 1 to 6.5 in. 

thick, of dark-gray (N3) to medium-darkgray (N4) fine-grained fossiliferous limestone that weathers medium light gray 

(M>) to light gray (W7) and light olive gray 

(5Y 6/1) and contains conodonts of early 

Middle Devonian age 

Thickness

Thickness 

(Feet) (Meters)

33.7 10.3

1.6 0.5

4.9

of Buttermilk Falls Limestone 40.2

1.5

12.3

Palmerton Sandstone:

8. Sandstone, generally very coarse grained; 

conglomeratic; with pebbles that are generally rounded and as much as 0.5 in. long; 

very light gray (M5) to medium-light-gray 

(N6) and dark-yellowish-orange (WYR 6/6) 

to grayish-orange (WYR 7/4); partly iron 

stained; thick bedded (beds about 2 to 25 

ft thick). Lower contact abrupt 104.0

7. Siltstone, light-gray (7V7), and lenticular very 

coarse grained sandstone in beds 0.4 to 

1.6 ft thick. Lower contact abrupt 3.5

31.7

1.1 

Thickness of Palmerton Sandstone 107.5 32.8

Schoharie and Esopus Formations, undivided: 

Schoharie Formation:

6. Siltstone to minor very fine grained sandstone; partly shaly; very pale orange 

(10 YR 8/6); fossiliferous; with mediumlight-gray (M>) nodular chert. Lower contact abrupt 13.5 4.1
REFERENCES CITED 33

5. Siltstone, siliceous; dark-gray (N3) to 

medium-dark-gray (A/4); with minor very 

fine grained sandstone; generally 

weathers from pale brown (5YR 5/2) to 

light brown (5YR 5/6); lower part contains 

silty shale in beds 2 to 5 in. thick and more 

massive siltstone to very fine grained 

sandstone in beds 3 to 9 in. in thickness; 

upper part is mostly siltstone to very fine 

grained sandstone in massive even beds 

as much as 3 ft thick; grayish-red (5R 4/2) 

siltstone, 8 in. thick, is 2.2 ft below top of 

unit. Abundant Taonurus. Lower contact abrupt 

Thickness 

(Feet) (Meters)

23.2 7.1 

Thickness of Schoharie Formation 36.7 11.2

Esopus Formation:

4. Siltstone, very shaly; medium-gray (A/5); 

fissile; thin-bedded (beds as much as 3 in. 

thick); Taonurus. Upper contact transitional through interbedded shaly siltstone 

and siltstone 3.0

3. Shale, silty; fissile; very light gray (A/8) to

olive-gray (55^ 4/1). Lower contact abrupt 8.0

Thickness of Esopus Formation 11.0

Thickness of undivided Schoharie and 

Esopus Formations 

0.9

2.4 

3.3

47.7 14.5

Oriskany Group (part): 

Ridgeley Sandstone:

2. Sandstone, generally medium- to very coarse 

grained; conglomeratic; with rounded 

quartz grains as much as 0.5 in. long; paleyellowish-orange (10YK 8/6); thin- to 

thick-bedded (beds range from 0.5 to 3 ft 

in thickness); upper 8 in. hematitic; base 

partly covered by rubble; probably transitional into underlying Shriver Chert; 

fault contact with overlying Esopus Formation so that unit is 5.6 ft thinner at 

road level below 26.9

Thickness of Ridgeley Sandstone of the 

Oriskany Group 26.9

Shriver Chert (part):

1. Chert, white (AT9) to very light gray (AT8); 

fossiliferous; thin-bedded (beds as much 

as 1 ft thick); interbedded with very pale 

yellowish-orange (1QYR 9/6) coarse- to 

very coarse grained conglomeratic sandstone with quartz grains as much as 0.4 

in. long. Base covered 6.0

8.2

8.2

1.8 

Incomplete thickness of Shriver Chert 6.0 1.8

Incomplete thickness of Oriskany

Group 32.9 10.0

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