er

of the Lower Delaware

Delmarva Peninsula, 

New Jersey, Pennsylvania, *-f / x / 7

GEOLOGICAL SURVEY PROFISSIOMAL PAPER

Upper Cenozoic Sediments 

of the Lower Delaware 

Valley and the Northern 

Delmarva Peninsula, 

New Jersey, Pennsylvania, 

Delaware, and Maryland

By JAMES P. OWENS and JAMES P. MINARD

SURFACE AND SHALLOW SUBSURFACE GEOLOGIC STUDIES IN THE 

EMERGED COASTAL PLAIN OF THE MIDDLE ATLANTIC STATES

GEOLOGICAL SURVEY PROFESSIONAL PAPER 1067-D

Two periods of gravel sedimentation 

have been outlined—one late Miocene 

and the other late Pleistocene

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1979
UNITED STATES DEPARTMENT OF THE INTERIOR 

CECIL D. ANDRUS, Secretary

GEOLOGICAL SURVEY 

H. William Menard, Director

Library of Congress Cataloging in Publication Data

Owens, James Patrick, 1924-

Upper Cenozoic sediments of the lower Delaware Valley and the northern peninsula, New Jersey, Pennsylvania, Delaware, 

and Maryland.

(Geological Survey professional paper ; 1067-D)

Bibliography: p.

Supt. of Docs, no.: I 19.16:1067-D

1. Geology, Stratigraphic Miocene. 2. Geology, Stratigraphic Pleistocene. 3. Gravel Northeastern States. 4. Geology 

Northeastern States. I. Minard, James P., joint author. II. Title. III. Series: United States. Geological Survey.

Professional paper ; 1067-D. 

QE694.093 551.7'S 78-606031

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

Washington, D.C. 20402

Stock Number 024-001-03194-9
CONTENTS

Page

Abstract- ————————————————— —— —————————————— - — - ————————— D1

i nysiograpny ——————— ——— • ———————————— - ————————— —— 

Regional geologic setting ————————————————————————————————————— 4

Beacon Hill Gravel ("Upland gravels") ————————————————————————— ®

Bridgeton Formation ("Arkose 2") ———————————————————————————— 8

Pensauken Formation ("Arkose 1") ——————————————————————————— 20

"Trenton gravel" —————————————————————————————————————— 2 9

Spring Lake beds ("Graywacke 2") ———————————————————————— 29

Van Sciver Lake beds ("Graywacke 1") ————————————————————— 39

A a References cited —————————————————————————————————————————— 4 "

ILLUSTRATIONS

Page

FIGURE 1. Map showing area (patterned) investigated in this report

2. Map of physiographic provinces and subprovinces of New Jersey

3. Modified map of physiographic provinces and subprovinces of New Jersey

4. Generalized lithologic map of region

5. Map of distribution of Beacon Hill Gravel in New Jersey

6. Photograph of Beacon Hill Gravel unconformity on Cohansey Sand northeast of Clarksburg, N.J

7. Photograph showing bedding style of Beacon Hill Gravel northeast of Clarksburg, N.J

8. Profiles across inner lowland near Trenton, N.J.

9. Photograph of Bridgeton Formation near Old Bridge, N.J ————————————————————————————————————— 10

10. Photographs of Bridgeton Formation near Woodstown and Bridgeton, N.J ———————————————————————————— H

11. Contour map of surface of Bridgeton Formation ——————————————————————————————————————————— 12

12. Contour map of base of Bridgeton Formation ———————————————————————————————————————————— 13

13. Map showing mean direction of crossbeds in Bridgeton Formation ———————————————————————————————— 15

14. Plot of moving averages of crossbedding orientation in Bridgeton Formation —————————————————————————— 16

15. Schematic map showing paleocurrent trends in Bridgeton Formation ——————————————————————————————— 17

16. Photograph of Pensauken Formation near Moorestown, N.J. ——————————————————————————————————— 21

17. Photograph showing iron oxide cementation in Pensauken Formation near Moorestown, N.J. ————————————————— 22

18. Photographs of Pensauken Formation at Palmyra, N.J ——————————————————————————————————————— 22

19. Photographs of Pensauken Formation at mouth of Elk River, Md ————————————————————————————————— 23

20. Photographs of Pensauken Formation near Harrington, Del ———————————————————————————————————— 24

21. Contour map of surface of Pensauken Formation ——————————————————————————————————————————— 25

22. Contour map of base of Pensauken Formation ———————————————————————————————————————————— 26

23. Map showing mean direction of crossbeds in Pensauken Formation ———————————————————————————————— 27

24. Plot of moving averages of crossbedding orientation in Pensauken Formation —————————————————————————— 28

25. Schematic map showing paleocurrent trends in Pensauken Formation ——————————————————————————————— 30

26. Location map of profiles drawn across Delaware River valley ——————————————————————————————————— 31

Hi
IV CONTENTS

Page

FIGURE 27-30. Cross sections of surficial deposits at locations shown in figure 26:

28. Profiles III and IV-———--———-—————————————-—————-—————————-———————————— 33

	30. Profiles VII, VIII, and IX———————————————————————-——————-——————-——————— 35

31. Photographs of coarse gravel and sand facies of Spring Lake beds at Penn Valley, Pa., and near Burlington, N.J —— 36

32. Photograph of basal gravel of Spring Lake beds at Palmyra, N.J——————————————————————————————— 37

33. Log of auger hole in "Fish House Clay" near Camden, N.J——————————————————————————————————— 38

34. Map showing direction of sediment transport during Spring Lake time———————————————————————————— 40

35. Photograph of gravelly facies of beds at Van Sciver Lake, south of Morrisville, Pa. ———————————————————— 41

36. Photograph of massive clay-silt near base of deposits at Artificial Island, N.J———————————————————————— 41

37. Photograph showing large-scale crossbedding in deposits at Artificial Island, N.J.————————————————————— 41

38. Composite section of excavation at Artificial Island, N.J ———————————————————————————————————— 42

39. Schematic map showing paleocurrent trends in Van Sciver Lake beds ———————————————————————————— 43

40. Map showing locations and shapes of the different units in the area of investigation———————————————————— 44
SURFACE AND SHALLOW SUBSURFACE GEOLOGIC STUDIES 

IN THE EMERGED COASTAL PLAIN OF THE MIDDLE ATLANTIC STATES

UPPER CENOZOIC SEDIMENTS OF THE LOWER DELAWARE VALLEY

AND THE NORTHERN DELMARVA PENINSULA 

NEW JERSEY, PENNSYLVANIA, DELAWARE, AND MARYLAND

By JAMES P. OWENS and JAMES P. MINARD

ABSTRACT

The "yellow gravels" referred to by R. D. Salisbury in 1898 and 

the "Trenton gravel," as defined by H. C. Lewis in 1880, were investigated along the inner edge of the New Jersey Coastal Plain in 

southern New Jersey and in the northern Delmarva Peninsula.

The highest level deposits, the Beacon Hill gravel, are found on only 

the highest hills in the New Jersey Coastal Plain. Their distribution 

suggests deposition from north to south across the plain. After deposition of the Beacon Hill, probably in middle or late Miocene time, a 

narrow valley was formed paralleling the inner edge of the New Jersey 

Coastal Plain between Raritan Bay and Camden. South of Camden, 

the valley broadened, covering much of southern New Jersey. The 

deposits in this valley are largely the Bridgeton Formation as we have 

redefined it. A second narrow valley was entrenched through the 

Bridgeton between Trenton and Salem, N.J. This valley broadens and 

covers much of the northern Delmarva Peninsula west of the Delaware 

River. The fill in the valley is largely the Pensauken Formation, as we 

have redefined it in our report. Collectively, the Beacon Hill, the 

Bridgeton, and the Pensauken were originally the "yellow gravels" 

of Salisbury. These deposits are all fluviatile in origin and were largely 

formed as a series of steplike downcutting channels.

The Delaware Valley between Trenton and the lower Delaware Bay 

region is occupied by the "Trenton gravel," which is below the average level of the "yellow gravels." Two units recognized throughout 

the area and informally named the Spring Lake beds and the Van 

Sciver Lake beds are lithologically distinct from the "yellow gravel" 

formations. The lithologies of the Spring Lake beds and the Van Sciver 

Lake beds are much more heterogeneous than those of the older formations. These two units, particularly, contain much greater amounts 

of silt and clay, often in thick beds. The depositional environments 

associated with the two units include fluviatile, estuarine, and marginal 

marine. Both these units are interpreted to be late Pleistocene (Sangamonian) in age.

INTRODUCTION

The late Tertiary and Quaternary was a time of extensive erosion of the inner emerged part of the northern 

Atlantic Coastal Plain, when large volumes of the Coastal 

Plain sediments and the adjacent Piedmont rocks were

stripped away and transported down the river systems 

to the now-submerged shelf. One large valley that served 

as a drainageway for these sediments paralleled the entire edge of the New Jersey Coastal Plain. This valley or 

lowland, which was called the "great Amboy-Salem 

trench" (Valley), by MacClintock and Richards (1936) is 

approximately 160 km (100 miles) long and a maximum 

of 40 km (25 miles) wide. As interpreted by nearly all 

investigators, the sediments within this valley are a record of multiple downcuttings and infillings associated 

with Quaternary glaciations in the Eastern United States 

(Salisbury and Knapp, 1917: MacClintock and Richards, 

1936, and Peltier, 1959). Actually, no firm evidence supports any specific age for most of the valley fill, but traditionally, these sediments are considered to be Quaternary.

In a general sense, the sediments in the valley that 

were not derived from older formations in the Coastal 

Plain can be separated into two general types—sediments that are extensively iron oxide stained and are referred to as the "yellow gravels" (Salisbury, 1898) and 

sediments that show little iron oxide staining, the "Trenton gravel" as defined by Lewis (1880).

The surficial deposits in the area in and around Trenton, N.J., were mapped by the authors at a scale of 

1:48,000 (Owens and Minard, 1975). The information we 

obtained permitted us to evaluate the valley-fill stratigraphy as mapped by Salisbury (1909) and described later 

in great detail (Salisbury and Knapp, 1917).

Using our data at Trenton as a basis, we made a detailed reconnaissance throughout the rest of the "great 

Amboy-Salem trench" (valley) of MacClintock and 

Richards (1936) and then into the gravel-capped uplands 

of southern New Jersey and west of the Delaware River 

in the northern Delmarva Peninsula (fig. 1). Our studies,

Dl
D2 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

77° 76° 75° 74°

37° —

FIGURE 1.—Outline of area (patterned) investigated in this report.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D3

which concentrated on the fluviatile and, to a lesser extent, the estuarine facies of the valley fill, are detailed in 

this report. The marine beds of presumed Quaternary 

age that fringe much of the southern Delaware-Maryland 

coast have been discussed by Owens and Denny (1978). 

Our study is highly speculative in many places because 

only reconnaissance mapping was done in areas discussed in this report, as opposed to the detailed mapping 

carried out in areas discussed in other chapters in this 

series.

PHYSIOGRAPHY

The area covered in our report includes parts of two 

major physiographic provinces—the Atlantic Coastal 

Plain and the Piedmont. These provinces, however, are 

too generalized to be of specific use at the scale of our 

study; we found it convenient to further subdivide the 

landforms in the Coastal Plain province. Earlier, the 

Coastal Plain was divided into three subprovinces, as 

shown in figure 2 (Owens and Minard, 1960; Minard and 

Rhodehamel, 1969). We have modified these earlier versions into the lowland, intermediate upland, and upland 

Coastal Plain subprovinces (fig. 3).

Altitudes in the lowland subprovince range from 0 to 

21 m (70 ft) above sea level. This subprovince forms a 

narrow lowland fringe along the Atlantic coast and up 

the larger stream valleys of this coastal region. The lowland, however, is best developed along Delaware Bay 

and the Delaware River as far upstream as Trenton, 

N. J. The higher altitudes (ca. 21 m; 70 ft) are mostly near 

Trenton. Smaller areas at approximately this altitude 

fringe the lower Delaware River and parts of Delaware 

Bay. Most of the lowland in this region is less than 7.4 m 

(25 ft) above sea level. This part of the lowland is separated from the higher elevations by a scarp that has a toe 

6 to 7.4 m (20 to 25 ft) above sea level. The scarp, however, is not continuous, having been removed from some 

areas by the many small streams that cross it. Most of 

these stream valleys and large areas at lower altitudes 

are covered by tidal marsh and swamp deposits. Areas 

at higher altitudes (above 7.4 m; 25 ft) are much sandier 

and better drained than are the lower lying areas.

The intermediate upland has altitudes that range from 

15 to 55 m (50 to 180 ft). This subprovince is separated 

into two major areas. One area is between Trenton and 

South Amboy in the Amboy-Salem trench of MaeClintock and Richards (1936); the other includes most of 

southern New Jersey.

In the Trenton-Amboy area, where the intermediate 

upland is less dissected, altitudes range from 30 to 55 m 

(100 to 180 ft). The higher altitudes are most common 

along the southeastern side of the valley. Two major exceptions to this distributional pattern, however, are near 

Franklin Park and just south of Trenton, where altitudes 

reach nearly 49 m (160 ft). The intermediate upland between Trenton and South Amboy is locally very dissected, producing a hilly topography, particularly near 

the Raritan River in the north and the Delaware River 

in the south. The rest of the area is relatively flat and is 

characterized by a sandy surface. The largest area of the 

intermediate upland is in southern New Jersey. Here,

39°

FIGURE 2.—Generalized map of physiographic provinces and subprovinces of New Jersey (Minard and Rhodehamel, 1969).
D4 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

Salem INTERMEDIATE

UPLAND 

Q Bridgeton

39°-

FIGURE 3.—Generalized map of physiographic provinces and subprovinces of New Jersey modified from Owens and Minard, 1960, and 

Minard and Rhodehamel, 1969. A-A' and B-B' are approximate 

locations of cross sections shown in figure 8.

altitudes range from nearly 46 m (150 ft) northwest of 

Salem to nearly 15 m (50 ft) just west of Atlantic City. 

Near Berlin, however, altitudes rise to nearly 55 m (180 

ft).

The intermediate upland is bounded on the west, south, 

and east by the lowland. On the north, this subprovince 

abuts against the higher altitudes of the upland subprovince. This junction is marked by a gently eastward sloping, highly dissected scarp. Many streams have cut into 

this intermediate upland and have produced a generally 

hilly terrain. The largest of these streams, the Mullica 

River, has cut a broad valley across the intermediate 

lowland and well into the bordering upland. Much of the 

upland and the intermediate upland has been removed 

by this stream. A small segment of the intermediate upland has been separated from the main part of this subprovince by this river. The surface of the intermediate 

upland is typically sandy and well drained.

The upland subprovince has altitudes ranging from 61 

m (200 ft) to nearly 122 m (400 ft). This subprovince covers most of the central and northern New Jersey Coastal 

Plain. The upland areas are more dissected than either 

of the other two subprovinces. This upland is very hilly 

and is characterized by isolated high hills surrounded by 

lower lying areas. Where intact, the upland surface is 

typically gravelly. Some of these surfaces are littered by 

iron oxide-cemented blocks.

REGIONAL GEOLOGIC SETTING

A generalized lithologic map of the rocks bordering the 

inner lowland is shown in figure 4. The Piedmont terrain 

along the northwestern part of the valley is a complex 

mixture of many rock types. Between Trenton and New 

Brunswick, the inner lowland subprovince is bordered by 

sedimentary rocks of Triassic age, mostly fine- to coarsegrained arkose of the Stockton Formation and, less commonly, red shale and red sandstone of the Brunswick 

Formation. Locally, large masses of diabase crop out 

near Princeton, N.J., and are a potential nearby source 

of mafic materials, particularly to the inner lowland in 

this region. These rocks form part of the Triassic lowlands section of the Piedmont physiographic province. 

From Trenton, N.J., to Wilmington, Del., the crystalline 

rocks crop out; these rocks are mainly metamorphic but 

also include some igneous rocks and a lesser amount of 

metasedimentary rocks of Precambrian and early Paleozoic age. Most of these rocks are very feldspathic, and 

locally some are abundantly micaceous, particularly the 

schist and gneiss of the'Wissahickon Formation. These 

rocks are part of the Piedmont Upland section of the 

Piedmont physiographic province. Sediments derived 

from the Triassic and Jurassic basin or from the older 

crystalline rocks have a high feldspar and mica content; 

hence, they normally provide immature sediments to the 

late Cenozoic valleys.

The Coastal Plain rocks of Late Cretaceous through 

late Tertiary age are a second major sediment source. 

These sediments are generally found to the east and 

southeast in addition to underlying most of the late Cenozoic valleys. In this area, the Coastal Plain sediments 

can be separated into three gross lithologic units: an up-
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA

77° 76° 75° 74°

D5

EXPLANATION

Coastal Plain sedimentary rocks

Triassic arkosic sands and gravel of the Stockton 

Formation; some diabase

Triassic red shale and sandstone of the Brunswick 

Formation; some diabase

New York City Group metamorphic and igneous 

rocks

New Jersey Highland gneiss and schist; abundant 

intrusive rocks

Piedmont metamorphic and igneous rocks

FIGURE 4.—Generalized lithologic map of rocks bordering the physiographic subprovinces shown in figure 3.

per sheet of quartz sand of Miocene beds; a middle interbedded clay and sand sequence, which contains large 

concentrations of glauconite and mica in addition to quartz 

and feldspar, in the Upper Cretaceous to Eocene beds; 

and a lower interbedded clay and sand sequence in which 

all the sand is quartz, in the lower part of the Upper 

Cretaceous beds. In summary, the Coastal Plain strata 

contributed large amounts of quartz and glauconite sand 

and lesser amounts of feldspar and mica to the inner lowland. Significant concentrations of feldspar are found in 

many of the formations (as much as 15 percent of the

sand fraction), but much of the feldspar is weathered and 

probably could not survive any extensive recycling. It is, 

therefore, the green glauconite sand that is unique to the 

Coastal Plain rocks. Its presence and quantity in the surficial alluvium is one of the best measures of contribution 

from the Coastal Plain formations.

Additionally, the Coastal Plain formations were a major source of clay and silt found in the alluvial-valley deposits. The types of clay contributed by each of the 

Coastal Plain formations were discussed in an earlier 

publication (Owens and Sohl, 1969).
D6 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

A third major sediment source is the glaciofluvial deposits derived from the areas north and northwest of the 

alluvial valleys. These deposits are distinguished from 

those of the other major sediment sources by the quantity of gravel and the large variety of immature rock 

types that they contain, such as limestone, and the abundant rock fragments in the sand fraction.

Some of the alluvial sediments may have been derived 

from more distant sources such as the folded Appalachians, but any contribution from such sources probably 

was small.

STRATIGRAPHY

The surficial sediments of the Trenton area were 

mapped in two major classes, those sediments largely derived from the Coastal Plain and those contributed from 

other major sources outside the Coastal Plain (Owens 

and Minard, 1975). This report will discuss mainly sediments derived from outside the Coastal Plain, or essentially those in the lowland and intermediate lowland. The 

non-Coastal Plain sediments have been separated into 

five units, four of which constitute the bulk of the surficial sediment in these subprovinces. The fifth, the Beacon Hill Gravel, as defined by Kiimmel and Knapp (1904), 

is a series of isolated gravel patches, generally small, 

which crop out on many of the highest hills within the 

upland subprovince.

Salisbury and Knapp (1917) divided the surficial sediments of New Jersey that are below the general level of 

the Beacon Hill into three formations: Bridgeton, Pensauken, and Cape May. The name Cape May seems least 

appropriate of the three for widespread use because it 

largely applies to the marine beds cropping out only in 

the lower Delaware River valley near the coast. Additionally, we will not discuss the fill of the present Delaware River and Bay. Some of the characteristics of these 

sediments have been discussed by Owens and others 

(1974).

The stratigraphy of the valley-fill sediments in those 

units, as defined above, is, from youngest to oldest, as 

follows:

Stratigraphy in this report

Comparable stratigraphic

nomenclature used in 1975

by Owens aiid Minard

Van Sciver Lake bed ————————————— "Graywacke 1."

Spring Lake beds —--—————————— "Graywacke 2."

Pensauken Formation -————-—-—«—- "Arkose 1."

Bridgeton Formation ————————————— "Arkose 2."

Beacon Hill Gravel ———————————— "Upland gravels."

It is very difficult to apply classical formation techniques to largely thin, often patchy fluviatile-estuarine

deposits in which facies changes are common. Because of 

the highly dissected nature of the older formations, correlation of isolated deposits over widely spaced areas 

was necessary in order to reconstruct the original shape 

of these formations. Some of the conclusions reached in 

this reconstruction, therefore, are speculative. Use of 

the term "formation" with a geographic name, however, is a good method for describing units that actually 

are a combination of lithology (rock stratigraphic) and 

areal position.

BEACON HILL GRAVEL ("UPLAND GRAVELS")

The name Beacon Hill was first applied to the upper 

gravelly beds of the "yellow gravels" by Salisbury (Salisbury and others, 1894). The name was subsequently 

dropped but was resurrected by Kiimmel and Knapp 

<1904). Owens and Minard (1975) referred to these deposits as "Upland gravels."

DISTRIBUTION AND LITHOLOGY

Many of the highest hills in the inner Coastal Plain upland, at altitudes of approximately 61-105 m (200 to 350 

ft), are capped by small patches of interbedded sand and 

gravel of varying thickness (to 12 m; 40 ft). Although 

these coarse clastic deposits are considered by most geologists to be Pliocene in age, no datable materials have 

been found in them. Their presumed antiquity is based 

upon their upland topographic distribution and upon 

their apparent advanced state of weathering, as shown 

by abundant iron oxide as grain coatings and cementation, weathered chert, and quartz clasts.

This upland gravel crops out at only a few localities in 

the New Jersey Coastal Plain, especially in a narrow 

band from Clarksburg on the north to Warren Grove on 

the south (Lewis and Kiimmel, 1912, and fig. 5). In the 

highlands of the Clarksburg area, these beds are well exposed in several pits(Minard, 1964). Here, as elsewhere, 

the gravel overlies the Cohansey Sand (Miocene); these 

gravel deposits form channel-shaped bodies that are unconformable on the older unit (fig. 6). The Cohansey is 

certainly post-Kirkwood (middle Miocene) in age and 

younger than the Yorktown (Pliocene); it therefore will 

be referred to as Miocene in age in this report. Throughout this area, the Beacon Hill is as much as 12 m (40 ft) 

thick. Typically, the upper beds are irregularly cemented by iron oxide into hard consolidated masses. 

These ironstone masses commonly overlie either extensively cross-stratified light-gray to reddish-brown sand 

or, more commonly, horizontally bedded sandy gravel 

(fig. 7). Most of the gravel in these lower beds is 2.5 cm 

(1 in.) in average diameter. Horizontally stratified sandy
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA

75°

D7

74°

40°

39°

o.Clarksburg 

Allentown/ 

Bordentown

*

EXPLANATION 

Outcrop of Beacon Hill Gravel

Hypothetical direction of 

transport of Beacon Hill 

Gravel

20 30 40 KILOMETERS

\ 

20 MILES

FIGURE 5.—Distribution of Beacon Hill Gravel in New Jersey (modified from Lewis and Kiimmel, 1912; revised by Johnson, 1950).
D8 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

FIGURE 6.—Beacon Hill Gravel unconformably overlying Cohansey 

Sand 1.4 km (0.9 mile) northeast of Clarksburg, N.J. Shovel head 

marks contact.

gravel is characteristic of many of the Coastal Plain upland deposits southwest of New Jersey (Schlee, 1957; 

Owens, 1969).

PETROLOGY

Pebble counts in the pits near Clarksburg have shown 

that quartz, quartzite, and chert are the principal constituents of the Beacon Hill. The presence of chert, locally in large concentrations, is also typical of the upland

FIGURE 7.—Exposure showing massive to poorly developed horizontal 

stratification in Beacon Hill Gravel 5.4 km (3.4 miles) northeast of 

Clarksburg, N.J. Pebbles are mainly chert.

deposits outside New Jersey (Schlee, 1957; Owens, 1969). 

The sand in the upland deposits is nearly all quartz, and 

the nonopaque minerals in the heavy-mineral assemblages are dominated by the more stable minerals such 

as zircon, staurolite, and sillimanite. Overall, the sediments in the Beacon Hill are mature.

MODE OF DEPOSITION AND ORIGIN

The similarity in composition, altitude, and stratification of the upland deposits in the Middle Atlantic States 

suggests a similar mode of deposition and possibly a similar time of origin (probably Miocene). Essentially, this 

idea was suggested by McGee (1888) in his definition of 

the highest level gravel throughout the Atlantic Coastal 

Plain.

All investigators of the gravel agree that it is subaerial 

in origin. Schlee (1957) favored a fluviatile origin for 

these beds; others (Campbell, 1931; Owens, 1969) have 

suggested an alluvial-fan origin. If the Beacon Hill Gravel 

is a stream deposit, then the parallel stratification would 

indicate deposition within the upper-flow regime and 

therefore in streams that had a high discharge (Harms 

and Fahnestock, 1965). We would favor this interpretation for the Beacon Hill rather than that of an alluvial-fan 

origin. The absence of fossils, animal burrows, and beachstratification, and the presence of a channel seem to preclude the possibility of a marine environment.

The distribution of the Beacon Hill sediments in New 

Jersey suggests transport from Morganville on the north 

to Warren Grove on the south (fig. 5). This directional 

pattern indicates a probable ancestral Hudson River 

transport for these deposits. The high concentrations of 

chert, low feldspar content, and mature heavy-mineral 

assemblage point to a probable Appalachian Mountain 

source. It seems likely that in post-Cohansey time (Miocene), a southward-flowing stream from the present 

Hudson River valley flowed across the New Jersey 

Coastal Plain to the Atlantic Ocean. These sediments 

predated, therefore, the formation of the Amboy-Salem 

valley of MacClintock and Richards (1936).

BRIDGETON FORMATION ("ARKOSE 2")

Salisbury (1898) named the Bridgeton Formation for 

a widespread blanket of surficial feldspathic sand. The 

type locality is at Bridgeton in southern New Jersey. 

Salisbury and Knapp (1917) later divided the Bridgeton 

into two phases, the "Glassboro" and the "Woodmansie." The Glassboro phase is mostly in southern New 

Jersey; the Woodmansie is mostly in the upland subprovince (fig. 3). The Glassboro phase, according to the authors, is locally an arkosic deposit. The Woodmansie 

phase is mainly a quartz sand.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D9

DISTRIBUTION AND LITHOLOGY

In and around Trenton, brightly colored sediments 

(various shades of yellow-orange, red, or brown) were 

mapped at two levels (Owens and Minard, 1975). These 

sediments were called "Arkose 1" (the lower, at altitudes of 12 to 24 m; 40 to 80 ft) and "Arkose 2" (the 

higher, at altitudes of 27 to 46 m; 90 to 150 ft). These 

beds, which are within the inner lowland (the AmboySalem valley of MacClintock and Richards, 1936), crop 

out well below the Beacon Hill Gravel.

The relationships of the arkosic sediments called "Arkose 2" by Owens and Minard in 1975, the oldest surficial unit, to other units in the Amboy-Salem valley is 

shown in figure 8. Section A-A' is a profile across the 

valley 4.8 km (3 miles) northeast of where the Delaware 

River enters this lowland from the northwest. In this 

area, highest level arkosic sediments underlie most of 

the valley, essentially at altitudes of 30 to 46 m (100 to 

150 ft) above sea level. Extensive drilling in this general 

area shows that the base of the highest arkosic sediments 

is highly irregular, consisting of many channels which locally extended to about 20 m (65 ft) above sea level. Section B-B' is a profile across the valley 9 km (3 miles)

southwest of the Delaware River—lowland subprovince 

junction. The highest level "Arkose 2" sediments in this 

part of the valley occur only on scattered hills or along 

the valley edge at altitudes of 30 m (100 ft) or more. This 

profile also shows in more detail the physiography of the 

lowland subprovinces (fig. 3) at the northernmost extent 

of both subprovinces. The rapid change from the lowland 

to intermediate upland in this area is also evident in 

these profiles.

"Arkose 2" near Trenton is an extensively cross 

stratified feldspathic quartz sand stained reddish brown 

to depths of as much as 5 m (15 ft). Widespread black 

iron(?) oxides in this weathered zone occur as small circular segregations or as thin laminae in the lighter colored cross strata. Below the reddened zone, the sand is 

either yellow or white and irregularly stained reddish to 

orange brown. Locally, beds of fine gravel are present, 

but distinct layers of clay or silt are rare in this region.

Northeast of the area of section A-A', "Arkose 2" 

has about the same lithology as at Trenton. Thus, near 

Raritan Bay, where these deposits are widely dug, as 

shown in a typical exposure (fig. 9), they are mostly a 

light-colored cross-stratified sand containing scattered

A

METERS

75 ,

50

25 

SEA 

LEVEL

/Tar2

Tar2

Qgw2 

Qal not shown in section

PRE-UPPER TERTIARY DEPOSITS

VERTICAL EXAGGERATION X 40

PRE-UPPER TERTIARY DEPOSITS

-25

0 .5 1 3 KILOMETERS

VERTICAL EXAGGERATION X 40

n I I 

0 '/2 1 2 MILES

EXPLANATION

"Graywacke 1" (Van Sciver Lake beds) 

"Graywacke 2" (Spring Lake beds) 

"Arkose l"(Pensauken) 

"Arkose 2" (Bridgeton)

FIGURE 8.—Profiles across the inner lowland near Trenton, N.J. Section A-A' is 4.8 km (3 miles) northeast of where the Delaware River 

enters the inner lowland. Section B-B' is 4.8 km (3 miles) southeast of point. Approximate location of sections is shown in figure 3.
DIG GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

FIGURE 9.—Feldspathic quartz sand of Bridgeton Formation ("Arkose 

2") in upper valley at Old Bridge, near Raritan Bay, N.J. Maximum boulder size in deposit at this locality is about 61 cm (24 in.). 

Bulk of gravel is mostly vein quartz, chert, and quartzite. Smaller 

amounts of red shale, red sandstone, crystalline rocks, and rounded 

ironstone gravel are also present.

pieces of gravel. Not shown in this photograph but present in most exposures in this area are the near-surface 

more massive reddish sandy beds.

Small fan-shaped masses are present at places along 

the border of "Arkose 2" in this region. These fanshaped deposits, which are generally at somewhat higher 

altitudes than are the surficial sediments in the main valley, apparently were deposited in tributaries to the main 

(Bridgeton; "Arkose 2") valley. The tributary sediments differ between localities, reflecting, in large part, 

the rocks in their drainage basin. In one such fan-shaped 

deposit near Englishtown, for example, the tributary 

sediments are very glauconitic, thus indicating a Coastal 

Plain and specifically a marine Upper Cretaceous-lower 

Tertiary strata provenance.

From southwest of Trenton to the vicinity of Clementon, "Arkose 2" only occurs on scattered high hills similar to those shown in section B-B' (fig. 8). In southern 

New Jersey, the intermediate upland (fig. 3) is capped 

by "Arkose 2." This upland, which is the largest (but 

discontinuous) exposure of this unit in New Jersey, covers approximately 3,072 km2 (1,200 sq. miles). The lithology of the beds in this area is very similar to that in the 

north (fig. 1QA and B). The same general arrangement of 

massive dark-red very clayey sands over a lighter colored extensively coarse stratified sand (fig. 10A, specifically) is common throughout this region, as it is in many

FIGURE 10.—A. Bridgeton Formation 14.4 km (9 miles) northeast of 

Salem on southeast edge of Woodstown, N.J. Surface altitude of pit 

about 49 m (160 ft). Note upper massive clayey unit at top of formation, a characteristic of this unit.

areas northeast of Trenton. The type locality of the 

Bridgeton Formation, at Bridgeton, N.J., as defined by 

Salisbury (1898), is in this area, and we shall adopt this 

name for "Arkose 2" henceforth in this report. We wish 

to reiterate that our definition of the Bridgeton differs 

from that of Salisbury and Knapp (1917), mainly because 

we have included the surficial beds of the intermediate 

upland between Trenton and South Amboy in the Bridgeton rather than in another unit (Pensauken) as they did. 

The type exposure of the Bridgeton no longer exists. 

The closest exposure of the Bridgeton Formation in this 

area is shown in figure 105, and, as can be seen, the 

Bridgeton is here a cross-stratified sand. To the west, 

the Bridgeton maintains much the same lithology but has 

in addition many thin brown clay-silt beds.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA Dll

FIGURE 10.—B. Bridgeton Formation in southern New Jersey, 9.75 km (6.2 miles) due west of Bridgeton, N.J. Sandy and gravelly nature of 

formation can be seen. The scale of cross stratification is larger here than normal, but the dark massive upper clayey sand is still present.

CONFIGURATION OF THE BRIDGETON VALLEY FILL

On the basis of mapping and drilling near Trenton, reconnaissance north and south of this area, and a review 

of the literature, two maps were constructed. One shows 

the contours on the surface (fig. 11) and the other, contours on the base (fig. 12) of the Bridgeton Formation. 

The surface map was drawn by plotting the highest altitude at which the Bridgeton was found in any given 

quadrangle. Because parts of the intermediate upland 

subprovince are very dissected, restoration of the surface contours sometimes required projections over large 

distances. These contours thus are generalized and locally are very speculative. Other areas are urbanized, 

and exposures are few; in these areas, contours were

drawn on the basis of interpretations in other geologic 

literature (mostly Greenman and others, 1961).

The contour map on the base of the formation was 

based on the average value of the lowest altitudes noted 

in any given sector of the quadrangle. In some areas, a 

few channels extended below this average altitude, but 

their depth was so anomalous to the general pattern that 

they were disregarded.

In general, the map (fig. 11) shows the down valley 

slope at the top of the Bridgeton from an altitude of more 

than 56 m (180 ft) near Old Bridge in the upper part of 

the valley to about 15 m (50 ft) near Pleasantville in the 

lower part. The gradient pattern is complicated by the 

tributary valleys along the edge of the Bridgeton outcrop. Five of the larger tributary valleys are shown on
D12 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

RARITAN

-- BAY

PENNSYLVANIA

DELAWARE BAY Approximate outcrop limit of the

Bridgeton Formation

Contour interval in feet—Queries indicate 

the contours on surface of formation 

are unknown

FIGURE 11.—Contour map showing configuration of the surface of the Bridgeton Formation.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA

75°

D13

Woodbridge^ $Jj ISLAND 

Metuchen

lamesburg 

Englishtown

PENNSYLVANIA

EXPLANATION

Approximate outcrop limit of the

Bridgeton Formation 

Contour interval in feet—Queries indicate 

the contours on base of formation 

are unknown

40 KILOMETERS

FIGURE 12.—Contour map showing configuration of the base of the Bridgeton Formation.
D14 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

this map; near Englishtown, Franklin Park, Silver Lake, 

Clementon, and Tuckerton. These tributary valleys typically are at higher altitudes than the main- or trunk-valley fills. In addition, the map also shows significant variations across the main valley. For example, the surface 

of the Bridgeton slopes from an altitude of more than 56 

m (180 ft) near Old Bridge on the eastern edge of the 

valley to about 36 m (120 ft) on the western side near 

Metuchen.

In southern New Jersey, the Bridgeton has a general 

southeastward slope from about 46 m (150 ft) in the 

northwest to 15 m (50 ft) in the southeast. Two exceptions to this pattern in this southern area are near Clementon and Tuckerton. At Clementon, one of the fanshaped masses present along the valley edge is at higher 

altitudes than the Bridgeton of the valley to the west. 

Here the Bridgeton is at altitudes of slightly more than 

56 m (180 ft). The sediments of the beds in this fanshaped mass are similar in appearance to those shown'in 

figure 10A but have significantly lower feldspar content. 

These tributary-valley sediments were derived in large 

part from the quartz-rich Cohansey Sand, which crops 

out in the upland to the east. In addition, reworked pieces of ironstone from the older formations are common 

gravel constituents.

Although many fewer control points were used to construct the contour map drawn on the base of the formation (fig. 12) than were used to make the surface-contour 

map (fig. 11), the data complement the surface map. In 

general, where the surface of the deposits is lower, the 

base of the deposits is lower. This relationship suggests 

that the Bridgeton was formed by a series of channels 

that progressively downcut as they migrated across the 

Bridgeton valley. The alluvium in the channels coalesced 

to form a continuous but sloping sheet of gravel across 

the intermediate upland. The absence of high-altitude 

deposits south of Allentown and north of Clementon (fig. 

11) suggests that the Bridgeton river removed the older, 

higher deposits here as it migrated westward, downcutting to progressively lower altitudes. Thicknesses within 

the Bridgeton vary, largely depending upon the amount 

of postdepositional stripping. In those areas where the 

sand appears less dissected, this unit averages 9 to 15 m 

(30 to 50 ft) in thickness. The maximum known thickness 

is, however, nearly 24 m (80 ft) near Allentown, N.J., in 

the northern intermediate upland (Owens and Minard, 

1966).

VECTORAL PROPERTIES

The widespread well-developed cross stratification in 

the Bridgeton makes this an ideal unit in which to study 

dispersal patterns based upon measurements of 

crossbedding directions. The mean direction of the 

crossbeds at all the major stations have been plotted in

figure 13. These data are the summation of 120 individual 

dip azimuth readings. The data show some scatter, but 

the trend of the crossbeds in the northern part of the 

Bridgeton valley parallels the outcrop pattern of the formation (that is, southwest). In the southern outcrop, azimuth readings are more scattered, but a general easterly 

and southeasterly trend is apparent.

Figure 14 recasts the data in a moving-average diagram. This technique has been used and discussed in 

many publications and has been summarized by Potter 

and Pettijohn (1963). In general, this type of diagram 

smooths out the scatter irregularities and focuses upon 

the major dip directions.

Techniques commonly used for plotting the azimuth 

data are a simple arithmetic mean (used by Schlee, 1957, 

on the gravelly sediments in southern Maryland), or a 

vectoral mean (used by Jordan, 1964, in Delaware). The 

first technique is simple to calculate but is not recommended for dip azimuth readings that have a wide scatter (Potter and Pettijohn, 1963). In such a case, the more 

complex vectoral calculation is recommended. If, however, the data have only moderate or small scatter, then 

the simple arithmetic mean is just as accurate (Potter 

and Pettijohn, 1963). Our data have sufficiently small 

scatter to use the simple arithmetic-mean technique. The 

resultant diagram (fig. 14) seems to bear out this contention. The calculated paleocurrent readings show a strong 

tendency to be oriented to the southwest in the northern 

part of the Bridgeton valley and to the south, then southeast, and finally eastward progressively down the valley. 

A comparison of these data with the figures showing the 

contoured top and base of the Bridgeton (figs. 11 and 12) 

suggests that the emplacement of the channels carrying 

the arkosic sediments into the southern valley is not unlike that in the northern valley; that is, a series of channels shifting and downcutting to progressively lower elevations. In the southern valley, the highest and 

presumably the oldest channels are in the northern wall. 

To the south-southwest, the younger channels progressively cut to lower altitudes; the lowest lying channels in 

the extreme southern end of the gravel sheet would 

therefore be the youngest. Essentially, this was the 

same explanation proposed by Hack (1955) and Schlee 

(1957) for the upland gravels of southern Maryland.

Figure 15 is a schematic representation showing the 

paleocurrent trends during deposition of the Bridgeton. 

This interpretive diagram is strikingly similar to the one 

by Schlee (1957) for the upland gravels (Brandywine) in 

southern Maryland. If correlations based on altitude 

have any validity, then the Bridgeton of New Jersey and 

Pennsylvania is younger than the upland gravel sheet of 

southern Maryland and represents another period of 

downcutting by one of the major streams in the northern 

Atlantic Coastal Plain.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA

75°

D15

Approximate outcrop limit of the 

Bridgeton Formation

0 10 20 30 40 KILOMETERS

i i i i

FIGURE 13.—Mean direction of crossbeds measured at several localities in the Bridgeton Formation.
DIG GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

Old Bridge

^(250) 

Jamesburg

Englishtown 

(234)

Woodstown

' (156) Elmer^ . . , , 

Salem _ v 0_52)_V- (133) Xv- ( -- -

(103) (101J

\ DEL/WAflE BAY 

\

Approximate outcrop limit of the 

Bridgeton Formation

FIGURE 14.—Plot of moving averages of crossbedding orientation in the Bridgeton Formation. Outcrop area of formation is divided 

into squares approximately 13 km (8 miles) on a side. The azimuthal average of the crossbedding was calculated from all readings 

within each square. The average crossbedding azimuth orientation for each square where readings were taken is shown as an 

arrow whose center is in the upper left-hand corner of the square. The actual average orientation in degrees is in the parentheses 

at the end of each arrow.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D17

Silver Lake/^v J,renlon

Approximate outcrop limit of the 

Bridgeton Formation

Hypothetical direction of sediment 

movement in Bridgeton channels 

—Queried where unknown

10 20 30 40 KILOMETERS

FIGURE 15.—Schematic plot of paleocurrent trends during deposition of the Bridgeton Formation. Direction of downcutting is shown

in southern New Jersey.
D18 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

PETROLOGY

The Bridgeton sand is, for the most part, very feldspathic. Because feldspar content generally exceeds that 

of rock fragments, this unit was earlier called an arkosic 

deposit ("Arkose 2" of Owens and Minard, 1975). Actually the sand in this unit ranges from an arkosic to a 

subarkosic deposit. In the northern outcrops of the 

Bridgeton, the major sand minerals are quartz, microcline, and plagioclase (most commonly oligoclase). In the 

southern outcrops, quartz and microcline are the principal sand minerals, and plagioclase is a rare constituent. 

Mica (principally muscovite) is locally abundant, but, for 

the most part, it is present in surprisingly low amounts. 

Along the southeast side of the upper valley, the feldspathic sediments of the Bridgeton are overlapped and 

less commonly interfinger with highly glauconitic sediments derived from the glauconite-bearing Upper Cretaceous and lower Tertiary formations exposed in the 

Coastal Plain upland to the east. Such sediments are particularly widespread in the large tributary to the main 

trunk of the upper valley near Englishtown, N. J.

The nonopaque heavy minerals in most of the Bridgeton Formation are characterized by a large number of 

species, notably the metamorphic minerals. Essentially, 

these assemblages are classed as a full (immature) suite 

and are decidedly less mature than those in the Beacon 

Hill. The major opaque minerals are ilmenite, leucoxene, 

and, locally, magnetite. Magnetite is particularly abundant in the northern outcrop area, especially from Trenton northeastward. The nonopaque minerals also show 

considerable variation from outcrop to outcrop, but from 

Trenton to Raritan Bay, these assemblages commonly 

have higher concentrations of hornblende.

Several authors have noted the occurrence of gibbsite 

in the upper beds of the feldspathic sand in the AmboySalem trench (Krebs and Tedrow, 1958; Lodding, 1961; 

and Bowman, 1969). Bowman also studied the distribution of gibbsite ("lateritization") in the feldspathic sand, 

principally between Camden and Raritan Bay. He 

adopted the existing stratigraphic terminology; hence, in 

his view, the formation of gibbsite was in the "Pensauken." We expanded this study to cover all the feldspathic sediments in New Jersey and the northern Delmarva Peninsula. We found that gibbsite (plus halloysite, 

kaolinite, and goethite) was abundant in the near-surface 

beds (our Bridgeton) but was less abundant in the nearsurface beds of the other formations of this region. In a 

crude sense, therefore, we examined the soil development within these units and noted that gibbsite and especially halloysite and endellite had formed as much as 9 

m (30 ft) below the surface in the Bridgeton. These minerals are, however, particularly abundant in the reddish 

to reddish-brown near-surface beds of the Bridgeton.

AGE

The age of the Bridgeton has always been speculative, 

but, as noted earlier, all previous investigators have considered this unit to be Pleistocene. The youngest unit overlain by the Bridgeton is the Cohansey Sand. Gibson 

(1970) considered the Cohansey to be equivalent to the 

Yorktown Formation, which is now thought to be early 

Pliocene in age (Hazel, 1971). Rachele (1974) studied the 

pollen and spores from the Cohansey Sand near Lakehurst, N.J. She favored a late Miocene or early Pliocene 

age range for the pollen assemblages. Actually, the age 

she cited (approximately 18 m.y.) would be early to 

early middle Miocene. In spite of these most recent studies, the age of the Cohansey must still be considered uncertain. All we can state with any degree of certainty is 

that the Cohansey overlies beds of early middle Miocene 

age (Kirkwood Formation = upper part of Calvert For- 

-mation of Maryland). The best data regarding the age of 

the Bridgeton is its stratigraphic relationship to the Pensauken Formation. The Pensauken Formation, which 

cuts the Bridgeton, is late Miocene in age; therefore, the 

Bridgeton is at least this old. If the unit is indeed Miocene rather than Pleistocene in age, the extensive weathering is easier to understand.

MODE OF DEPOSITION AND ORIGIN

Minor sedimentary structures and the channel shape 

of the sedimentary deposits within the Bridgeton are 

typical of those found in fluviatile environments. No marine or estuarine beds were found in this unit even near 

the coast, though Salisbury and Knapp (1917) thought 

marine beds might be present in this area. The most obvious features, abundant loose sand and gravel, extensive cross stratification, and lack of marine trace fossils 

are typical of channel-fill deposits, specifically point-bar 

and channel-lag gravels (Alien, 1965). The finer overbank deposits are also an important indicator of a fluviatile depositional environment, but they are only found at 

a few localities (the pits at Old Bridge and Woodstown). 

These overbank sediments, because of their high topographic position and fine-grained nature, may have been 

more easily eroded than the coarser clasts of channel-fill 

origin and hence were stripped off large areas.

The channels, which appear to be the major depositional environment in this unit, are spatially arranged 

higher on one side of the deposit than on the other. This 

arrangement suggests a series of migrating downcutting 

channels. This situation is evident in both the northern 

and southern outcrops. In the latter area, the degrading 

channels have formed a broad, sheet deposit similar to 

that formed by the upland gravels of southern Maryland 

(Hack, 1955; Schlee, 1957). Apparently a highland simi-
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D19

lar to the Coastal Plain upland (fig. 3) was once present 

over all of southern New Jersey. This upland was systematically eroded away as the channels first entrenched 

into it and then migrated southward against it during 

Bridgeton time, ultimately producing a relatively flat, 

southeast-sloping surface in this area. In the northern 

part of the valley, the migrating channels were restricted to a much smaller area, and in many areas, the 

older higher level deposits are absent; they probably 

were eroded as the lower level channels shifted from one 

side of the valley to the other. As a result, only remnants 

of these higher level deposits remain here. From the surface evidence still available in this upvalley area, the 

Bridgeton deposits downcut from altitudes somewhat 

more than 60 m (200 ft) above sea level to a low of about 

30 m (100 ft) across the valley. The base of the deposits 

ranges in altitude from 45 m (150 ft) to 18 m (60 ft) above 

sea level in this general area. In the southern part of the 

valley, the channels have surface altitudes as low as 15 m 

(50 ft) above sea level and bases as low as 8 m (25 ft). At 

the coast, the arkosic sediments appear to be fluviatile 

all the way to a subdued ocean-facing scarp where they 

are eroded or overlapped by younger sediments. How 

much farther eastward and southward those fluviatile 

beds extended is now conjectural, but Schlee and Pratt 

(1970) showed a large patch of "yellow gravels" off the 

coast of New Jersey that appears to be on trend with the 

direction of transport of the arkosic sediments.

Hack (1955) and Schlee (1957) both discussed the hypothesis, first advanced by Mackin, that the size and 

depth of the river occupying the channels could be determined from the thickness of the alluvium in any single 

channel. If this hypothesis is correct, then most of the 

Bridgeton channels averaged about 12 m (40 ft) in depth.

Studies of the crossbedding azimuths in the Bridgeton 

indicate that the major sediment transport in the northern part of the valley was from northeast to southwest, 

essentially paralleling the axis or thalweg of the AmboySalem valley of MacClintock and Richards (1936). This 

interpretation supports the view of Salisbury and Knapp 

(1917) as to the position of the main trunk of this stream 

beyond its present northeast limit. An ancestral Hudson 

drainage for this river system, therefore, is possible if 

not probable. Howell and Hale (1946) and, with less certainty, Campbell and Bascom (1933) suggested that the 

major trunk of the stream occupying this valley came 

from northern New Jersey rather than southeastern 

New York. In both these reports, the authors stressed 

the occurrence of black fossiliferous cherts, which they 

thought were derived from the Paleozoic limestones in 

northern New Jersey. Essentially the same sequence of 

rocks crops out along the present Hudson River drainage 

in southeastern New York. Some sediment also may

have been contributed from northern New Jersey rocks 

to the main valley. Figure 11 shows a tributary joining 

the main trunk in this area. In fact, the presence of another tributary of equal size directly across the valley 

near Jamesburg, N.J., suggests that this area was the 

confluence of two major tributaries joining the master 

valley northeast of this junction. The ancestral Hudson 

seems to have been the master stream in this area during 

Bridgeton time.

Evidence of the existence of a major ancestral Delaware River drainage during Bridgeton time is lacking, at 

least where the present river now enters the lowland at 

Trenton. Campbell and Bascom (1933) agreed with this 

interpretation, but not Salisbury and Knapp (1917) or 

Peltier (1959), who favored the existence of the Delaware as a major drainage way for these sediments during 

the entire Quaternary.

The crossbedding data in the southern outcrops suggest that the streams left the inner edge of the Coastal 

Plain and flowed southeast and east to the Atlantic and 

downcut across this region in arcuate-shaped channels. 

Salisbury and Knapp (1917), for the most part, were the 

only investigators to examine the Bridgeton in this 

southern region in any detail. Their conclusions regarding the depositional environment for these sediments in 

this area were vague. For example, they thought that 

the Bridgeton might be a marine unit. They did, however, recognize the regional eastward dip of the Bridgeton.

The coarseness and composition of the Bridgeton clasts 

led most previous investigators to postulate a glacial-outwash origin for this unit. Typically, however, outwash 

deposits are a complex of many lithofacies characterized 

by rapid textural variations. Certainly this is not true in 

the Bridgeton, where sand is by far the major constituent throughout its entire outcrop. Tectonic or eustatic 

effects then appear to have been a more likely cause or 

causes for the abundance of sand clasts in the Bridgeton. 

The youngest dated beds in the New Jersey Coastal 

Plain are the Kirkwood (middle Miocene) and, with less 

certainty, the Cohansey (middle? to upper middle? Miocene). The Cohansey crops out at altitudes of more than 

90 m (300 ft) and the Kirkwood, as much as 60 m (200 ft) 

above present sea level. Both are marine or marginal marine units; therefore, since Cohansey time, the New Jersey Coastal Plain has been uplifted at least 90 m (300 ft). 

The localization of the northern part of the Bridgeton 

roughly paralleling the course of the Hudson River also 

seems significant. Of all the river systems in the Middle 

Atlantic States, the ancestral Bridgeton and a short 

reach of the Potomac River are the only ones that parallel the Coastal Plain-Piedmont boundary. In the case of 

the northernmost part of the Bridgeton and its probable
D20 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

extension into the Hudson Valley, a fault-system control 

is possible if not probable. Certainly a horst-graben origin has been discussed for the Hudson-Lake GeorgeLake Champlain drainage basins (Isachsen and Wold, 

1977). We would suggest that localization of the northern 

part of the Bridgeton valley might have been controlled 

by this Hudson-Lake George fault system and that a major movement along this system took place in late Miocene time. Such a structural control would not only have 

localized the course of the Bridgeton river but would also 

have supplied fresh feldspathic clasts from the underlying crystalline rocks in the Hudson River valley.

PENSAUKEN FORMATION ("ARKOSE 1")

Salisbury (1898) named the Pensauken Formation. 

The type locality was the exposures of surficial sediments in gravel pits along Pensauken (now spelled Pennsauken) Creek at Palmyra, N.J. Later, Salisbury and 

Knapp (1917) provided a better definition of this unit; 

this definition has since been used by most investigators 

of the formation. Salisbury and Knapp believed that the 

Pensauken, like the Bridgeton, consisted of two major 

lithofacies. One lithofacies was primarily reworked 

Coastal Plain sediments; the other was primarily sediment derived from rocks outside the Coastal Plain. The 

reworked Coastal Plain rocks were characterized by 

glauconite sand and a low feldspar content, whereas the 

non-Coastal Plain sediments were typically very feldspathic.

Within the Amboy-Salem valley, Salisbury and Knapp 

(1917) proposed that the Pensauken clasts occurred in 

two distinct plains. The lower plain, Swedesboro, was 

nearest the Delaware River at altitudes of 15 to 24 m (50 

to 80 ft). This plain apparently could be traced from just 

northeast of Salem to Trenton. The higher plain, Woodstown, is at altitudes approximately 15 m (50 ft) higher 

than the Swedesboro plain. The Woodstown plain is 

southeast of the Swedesboro plain and can be traced 

from near Woodstown on to Trenton. Northeast of Trenton, Salisbury and Knapp (1917) could not recognize the 

twofold division of the Pensauken; the formation covered 

the entire valley, even though these deposits were at the 

level of the Woodstown plain.

Salisbury and Knapp (1917) proposed that the twofold 

morphological subdivision in the lower Delaware Valley 

also represented a lithologic subdivision. The lower Swedesboro plain deposits were largely arkosic, and the upper Woodstown plain deposits were largely reworked 

Coastal Plain sediments.

DISTRIBUTION AND LI1HOLOGV

In the Amboy-Salem valley at Trenton, sediments similar in lithology and color to the Bridgeton are present at

surface altitudes of 15 to 24 m (50 to 80 ft) above sea 

level. These sediments were mapped as "Arkose 1" 

(Owens and Minard, 1975); together with the Bridgeton 

and Beacon Hill, they were originally the "yellow gravels" of Salisbury (1898).

The arkosic sediments are in two tiers at Trenton (fig. 

8); the higher tier was mapped by us as "Arkose 2" 

(Bridgeton) and the lower, as "Arkose 1." This relationship is critical in evaluating the Salisbury and Knapp 

interpretation of the geology of these sediments. These 

authors believed that the regional gradient of the Bridgeton as determined in southern New Jersey would preclude beds of this age being present at Trenton. Our 

interpretation differs in that we recognize two periods of 

arkosic sedimentation (Bridgeton and "Arkose 1").

The outcrop pattern of "Arkose 1" is very narrow just 

north of Trenton. Here these sediments were recognized 

only in the Assunpink Creek valley. Salisbury and Knapp 

(1917) traced similar sediments north of Assunpink Creek 

valley a short distance into the valley of the Millstone 

River. North of this area, no "Arkose 1" sediments 

have been reported.

Just south of Trenton, the outcrop of "Arkose 1" 

broadens; these sediments occur locally in valleys between interflures capped by the Bridgeton Formation. 

The base of "Arkose 1" is irregular, consisting of a series of channels, some of which extend nearly to sea 

level. "Arkose 1" in this general region consists typically of interbedded sand and gravelly sand (fig. 16).

Most of the gravelly beds are horizontal, and the sand 

is horizontal to crossbedded (typically large amplitude, 

about 1 m (3 ft). The gravel in this unit at Trenton is 

typically coarse; boulders to 1.5 m (5 ft) in size are common. The gravel in "Arkose 1" is typically coarser than 

in the higher level Bridgeton deposits in this general 

area. The gravel assemblage in "Arkose 1" is heterogenous, consisting largely of quartz, quartzite, and chert. 

Saprolitized crystalline and metamorphic rocks are present, as are red sandstone, siltstone, and shale (Triassic). 

Another common feature in the "Arkose 1" beds is 

widespread cementation of the sand and gravelly sand 

(fig. 17).

Southwest of Trenton, the outcrop of "Arkose 1" 

broadens, and near Moorestown, it merges with the 

Swedesboro plain of Salisbury and Knapp (1917). Included in the plain downvalley is the type locality of the 

Pensauken Formation at Palmyra, N.J. Therefore, we 

now would include "Arkose 1" in the Pensauken Formation but would restrict its usage in New Jersey to the 

sediments largely underlying the Swedesboro plain.

The type locality of the Pensauken has long since been 

mined out. Pits in the same general region, however, 

were still available at the time of our investigation (fig. 

18). The Pensauken beds here are largely iron oxide-ce-
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D21

FIGURE 16.—Pensauken ("Arkose 1") beds at Turkey Hill, 3.8 km (2.4 miles) south of Morrisville, Pa. Hill has surface altitude of nearly 24 m 

(80 ft). Bedding in this formation is largely horizontal, although locally the sandy beds have large-scale (>1 m; >3 ft) crossbeds.

merited, extensively cross-stratified feldspathic sand. 

Not shown in this photograph are thin horizontal beds of 

glauconite sand that overlie the feldspathic beds 

throughout most of this region. Thus, at the type locality 

on the Swedesboro plain, both major lithofacies of the 

Pensauken are present and are not restricted to separate 

plains as reported by Salisbury and Knapp (1917). This 

spatial relationship of glauconite sand over feldspathic 

sand is similar to that noted at several locations in the 

Bridgeton Formation. We mapped the glauconite sand, 

however, as a separate unit (as in Owens and Minard, 

1975).

Exposures of the Pensauken arkose beds are few in 

New Jersey. In the northern Delmarva Peninsula, however, exposures of the surficial beds of arkosic composition are widespread, particularly along the Chesapeake 

and Delaware Canal and west along Chesapeake Bay and 

its major tributaries (fig. 19). In the upper peninsula 

area, the provenance of the arkosic deposits is of considerable interest because of the proximity of these beds to 

the Susquehanna River drainage. Elk Neck, a small promontory, projects into the northern part of the bay 

across the trend of the Susquehanna River. Altitudes in 

the central part of this promontory reach a maximum of
D22 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

FIGURE 17.—Iron oxide-cemented beds in the Pensauken Formation 

on north side of Centerton Road, 4 km (2.5 miles) east of Moorestown, N.J.

nearly 120 m (400 ft) above sea level or well above the 

surface level of the nearby Pensauken beds to the east. 

Along the east side of the promontory, arkosic beds form 

a series of descending terrace deposits. On the west side 

of this landform, no similar arkosic terraces or beds are 

present. Additionally, no sediments of Pensauken lithology are present in the lower Susquehanna valley. On the 

basis of these observations, the Pensauken beds in the 

Delmarva Peninsula are probably of Delaware Valley origin. Well south of Elk Neck, some arkosic sediments of 

the Pensauken lithology might possibly have been introduced into the Delmarva Peninsula from the Susquehanna River, but there is no strong evidence to support 

such a supposition. We have concluded that most if not 

all the Pensauken sediment in the Delmarva Peninsula 

was transported here from the Delaware River valley. 

Southward down the peninsula, abundant clay-silt beds 

are found in the Pensauken, although sand, locally gravelly sand, is still dominant. Iron oxide staining and local 

cementation are common, as are light-green clay galls 

(fig. 20). Along an irregular line running from Salisbury, 

Md., to Milford, Del., the Pensauken is overlapped by 

younger formations and is only known in the subsurface 

southeast of the line.

CONFIGURATION OF PENSAUKEN VALLEY FILL

In general, the shape of the Pensauken Formation is 

similar to that of the Bridgeton, that is, narrow upper 

valley fill and broad lower valley fill. When the surface of

FIGURE 18.—A. Pensauken Formation near type locality at Palmyra, 

N.J. Pit on west side of U.S. Route 73, 0.4 km (0.25 mile) from 

junction with U.S. Route 130. Beds are extensively stained and locally cemented by iron oxide. B. Close-up of base of cut shown in A, 

illustrating style and scale of cross stratification in the Pensauken 

in the northern part of the outcrop.

the Pensauken (fig. 21) is compared with that of the 

Bridgeton (fig. 11), it is evident that the two-arkoses 

concept within the "yellow gravels," as postulated by 

Salisbury and Knapp (1917), is indeed valid in a regional 

sense. Clearly, the surface of the Pensauken has an average lower surface altitude than that of the Bridgeton. 

The map also shows the regional southeast slope of these 

beds as opposed to the southwest slope of those in the 

Bridgeton.

Figure 22 also shows the general southeast slope of the 

deposits. This map, however, also reveals an unexpected
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D23

FIGURE 19.—A. Pensauken Formation north of the Elk River in the upper Chesapeake Bay region. Here the Pensauken is in a well-defined 

channel in the Potomac Group of Cretaceous age. Channel fill is largely sand with a thick gravel layer near the top and is approximately 24 

m (80 ft) thick. B. Close-up of planar crossbedding and thicknesses of crossbeds at this locality.

low paralleling Elk Neck in the northern part of the 

lower valley. These beds may be a younger unit but have 

no fossils, and because of the similarity of the lithology 

to that of the rest of the Pensauken, we have included 

these beds in the Pensauken Formation.

PETROLOGY

Some authors have suggested that a lithic differentiation between the Pensauken and Bridgeton is not possible (MacClintock and Richards, 1936). Others have reported it possible but very difficult (Salisbury and Knapp, 

1917). In our interpretation of these two formations, the 

only area where they are in contact is in the inner lowland (fig. 3) between Trenton and Salem, N.J. We mapped 

part of this lowland in detail near Trenton (Owens and 

Minard, 1975) and found that in addition to the differences in altitude between the two units, each had mappable lithic differences. Figure 18 shows a typical lithology in the Pensauken near Palmyra, N.J., where the 

formation consists of interstratified sand and gravelly 

sand. Gravel of the size and concentration shown are 

common in the Pensauken but are uncommon in the

Bridgeton in this area. Another lithic difference is in the 

much larger concentrations of reworked Coastal Plain 

sediments in the Pensauken; such concentrations are evidenced by larger amounts of glauconitic sand even in the 

highly feldspathic beds and channels largely filled by 

Coastal Plain quartz gravels near the present Delaware 

River. Salisbury and Knapp (1917) observed that this 

Pensauken sand commonly was cemented by iron oxide. 

We noted that this cementation certainly was present in 

this area (fig. 17) and was common at several localities 

downvalley from the Trenton area. In fact, many of the 

characteristics just cited can be found in the Pensauken 

beds throughout the upper part of the valley.

Petrographic studies of the sand throughout the Pensauken show that it is mostly a subarkose but locally is 

either feldspathic enough to be classed as an arkose or 

quartz-rich enough to be classed as a protoquartzite. 

Typically, the Pensauken sand contains both plagioclase 

(oligoclase) and microcline in both New Jersey and the 

Delmarva Peninsula. This distribution in the Pensauken 

is in marked contrast to that of the Bridgeton in which 

the two feldspars are present only in the northernmost 

outcrops of that formation.
D24 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

FIGURE 20.—A. Pensauken Formation near Harrington, Del. Pit is near the southern edge of the Pensauken outcrop. The formation here is still 

largely sand. Crossbedding is less distinct and on a smaller scale on the average than in the upvalley regions. B. Closeup showing the 

indistinct crossbedding and a row of pale-green rounded clay clasts. Clay galls of this type are common in the Pensauken in the downvalley 

region.

The nonopaque heavy minerals in the Pensauken include a full or immature suite similar to the heavy-mineral assemblage in the Bridgeton. In the opaque suite, 

however, magnetite is much more abundant and widespread in the Pensauken that it is in the Bridgeton.

X-ray studies of the clay-silt fraction of the Pensauken 

surface and near-surface sand also reveal an important 

difference in mineralogy as compared with that of the 

Bridgeton sand. Gibbsite, which is so abundant in the 

upper several feet of the Bridgeton sand, is absent or 

sparse within much of the Pensauken Formation. The 

general absence or small concentration of gibbsite in the 

upper sand of the Pensauken was noted in all the outcrops shown in figures 16 through 20, which include the 

sections sampled near the type locality of this unit at Palmyra, N.J.

The clasts in the Pensauken indicate derivation in 

large part from the very feldspathic rocks of the Piedmont province, as evidenced by the large amount of plagioclase in the Pensauken both in New Jersey and in the 

Delmarva Peninsula. Contribution of sediment from the 

Bridgeton (mainly reworked ironstone) and other Coastal 

Plain formations (mainly glauconitic sand), although significant, was probably small in comparison with "new" 

sediment derived from the crystalline rocks of the Piedmont.

VECTORAL PROPERTIES

The sand of the Pensauken Formation is exceptionally 

well cross stratified. (See figs. 18-20.) The azimuths of 

crossbedding directions were measured at several localities in the upper valley (fig. 23). Most of the crossbedding data from the Delaware part of the Delmarva Peninsula came from a report by Jordan (1964). Figure 24 is 

a plot of the moving averages of the crossbedding azimuths in this unit and clearly shows a more southerly 

trend than in the Bridgeton sediments of southern New 

Jersey.

AGE

As stated earlier, all previous investigations except for 

ours (Owens and Minard, 1975) considered the Pensauken to be Pleistocene in age. All the dating of this unit is 

based upon poorly preserved leaves (Berry and Hawkins, 1935) and poorly described flora (Rollick, 1899). The 

stratigraphic position of these fossil localities, all in New 

Jersey, is uncertain. Our definition of the Pensauken includes the extensive surface sand and gravelly sand of 

the northern Delmarva Peninsula. In the southern limit 

in this peninsula, beds of Pensauken lithology interfinger 

with thick black-clay beds. Pollen and spores obtained 

from the black clay show that the pollen assemblage is
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA

76° 75°

D25

Approximate outcrop limit of 

the Pensauken Formation — 

Queried where doubtful

Contour interval 10 feet

39°

FIGURE 21._Contour map showing configuration of the surface of the Pensauken Formation.
D26 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

76° 75°

PENNSYLVANIA

NEW JERSEY

Approximate outcrop limit of 

the Pensauken Formation — 

Queried where doubtful 

Contour interval 25 feet Cambridge 

MARYLAND 0 10 20 KILOMETERS 

0 10 MILES

39°

FIGURE 22.—Contour map showing configuration of the base of the Pensauken Formation. Contour interval is in feet. Note low or saddle

in base of formation east of Elk Neck.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA

76° 75°

D27

Approximate outcrop limit of 

the Pensauken Formation — 

Queried where doubtful

Mean direction of cross beds

39° —

FIGURE 23.—Mean direction of crossbeds in Pensauken Formation.
D28 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

76'

Approximate outcrop limit of 

the Pensauken Formation— 

Queried where doubtful

FIGURE 24.—Plot of moving averages of crossbedding orientation in the Pensauken Formation. The method used to construct this plot is

the same as that described in figure 14.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D29

dominated by pine (Pinus), hickory (Carya), and oak 

(Quercus). Locally, the Asian walnut (Pterocarya) is 

very abundant. The presence of Pterocarya indicates a 

Tertiary age for this unit (L. A. Sirkin, written commun., 1974).

South of Salisbury, Md., the Pensauken grades into 

the very carbonaceous fossiliferous beds of the "Yorktown and Cohansey (?)" Formations as used by Rasmussen and Slaughter in 1955. The macro- and microfossils in these beds have been dated as late Miocene (B. W. 

Blackwelder and J. E. Hazel, written commun., 1974). 

The Pensauken is, therefore, of late Miocene age. Stratigraphic relationships, as we have outlined, indicate 

that the Pensauken is younger than the Bridgeton, and, 

therefore, by inference, the Bridgeton is also at least this 

age or older.

MODE OF DEPOSITION AND ORIGIN

The body geometry and bedding characteristics of that 

part of the Pensauken covered in this report are similar 

to those of the Bridgeton, suggesting that this part of the 

Pensauken and the Bridgeton were formed in a similar 

fluviatile environment. If this interpretation is correct, 

then the Pensauken as far southwest as the northern 

Delmarva Peninsula formed in a series of shifting downcutting channels similar to those described herein for the 

emplacement of the Bridgeton gravelly plain. In the Pensauken, however, the channels downcut progressively to 

the southeast and east (shown schematically in fig. 25), 

whereas those in the Bridgeton downcut to the southwest (fig. 15). The emplacement of this gravelly plain, 

therefore, contributed to the formation of the Delmarva 

lowland between the much higher Coastal Plain highlands to the northeast in New Jersey and to the west in 

southern Maryland. No evidence precisely establishes 

the age of the Pensauken within the area discussed in 

this report. As will be detailed in a companion report 

(Owens and Denny, 1978), however, the age of this unit 

to the south appears to be latest Miocene, not Pleistocene. Such an age has at least two very favorable aspects. First, it helps explain the weathering found 

throughout almost the entire unit (these beds had more 

time to be oxidized subaerially); secondly, it provides 

clues to the effects of the emergence of nearly half of the 

northern Atlantic Coastal Plain after the initial early(?) 

Miocene submergence of much of this region. Apparently 

the uplift of the northern Atlantic Coastal Plain was accompanied by reactivation of the Salisbury Embayment 

structure (essentially a downwarp; the gravels of Miocene age were transported and in part deposited in this 

very large continental sag or syncline). The Pensauken 

gravels represent one tectonic episode in the massive 

epeirogenic movement of the eastern continental block.

"TRENTON GRAVEL"

The name "Trenton gravel" was proposed by Lewis 

(1880) to apply to "the newest and last gravels found in 

the lower Delaware valley."

This very gravelly sand crops out in a large area in the 

present Delaware River valley, particularly near Trenton. It is below the general level of the Beacon Hill, the 

Bridgeton, and the Pensauken, and is the youngest sequence in the lowland physiographic subprovince (fig. 3).

Lithologically, this sand is distinct from all the previously described units, being an overall gray or pale reddish brown rather than the yellow or dark reddish brown 

of the Beacon Hill, the Bridgeton, and the Pensauken. 

Other lithic characteristics can also be used to separate 

the units, and these will be discussed shortly. Collectively, these low-lying gravels were grouped into the 

Cape May Formation by Salisbury and Knapp (1917), 

even though Fuller (1914) had noted these deposits at 

two distinct levels—6 m (20 ft) and 12-18 m (40-60 ft). 

Subsequent investigators of these sediments, notably 

MacClintock and Richards (1936), Peltier (1959), and 

Owens and Minard (1975), concurred with Fuller's conclusion that the low-lying "Trenton" gravelly deposits 

could be divided into two lithic units. Although the deposits are roughly at the levels suggested by Fuller 

(1914), the sediments at both levels are lithically very 

similar (the Bridgeton-Pensauken lithic problem repeated).

We have given these deposits provisional locality 

names; the higher level deposits mapped as "Graywacke 

2" (Owens and Minard, 1975) will be discussed under 

the heading Spring Lake beds, whereas the lower lying 

beds mapped as "Graywacke 1" will be discussed as the 

Van Sciver Lake beds. Figure 26 shows the location of 

profiles across the Delaware River from north of Trenton. Figure 27 is our interpretation of the published 

(Greenman and others, 1961) and unpublished data from 

borings from Scudders Falls on the north (Profile I) to 

the Cape May peninsula on the south (Profile IX). The 

profiles show the distribution of post-Pensauken beds 

within the Delaware River valley.

SPRING LAKE BEDS ("GRAYWACKE 2") 

DISTRIBUTION AND LITHOLOGY

Deposits having surface altitudes of 10.4-21 m (35- 

70 ft) are present in the upper reaches (fig. 3) of the lowland subprovince between Trenton, N.J., and Philadelphia, Pa. (figs. 27-30, Profiles I-IX). Most of these deposits are within the Delaware River valley except at 

Trenton, where they trend away from this valley to the 

northeast up the valley of Assunpink Creek. (See geologic map of Trenton area, Owens and Minard, 1975.)
D30 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES 

76° 75°

PENNSYLVANIA

NEW JERSEY

Approximate outcrop limit of 

the Pensauken Formation — 

Queried where doubtful

Theoretical direction of 

sediment transport in 

Pensauken channels

Cambridge 

MARYLAND 0 10 20 KILOMETERS

39°

FIGURE 25.—Schematic diagram of paleocurrent trends during the deposition of the Pensauken Formation.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D31

'Pennsylvania Turnpike Bridge

NEW JERSEY

Tacony Bridge 

PhaadelphiaS4-*fFish House o° 

Camden

39° —

FIGURE 26.—Location of profiles (shown as heavy line) drawn across Delaware River valley (fig. 3). Data used to construct profiles 

came from many published and unpublished sources but largely from Greenman and others (1961).
I.—Section at Scudders Falls Bridge

IL—Section from Trenton, New Jersey to Morrisville, Pennsylvania

SEA 

LEVEL

TRIASSIC ROCKS

Artificial w Water

EXPLANATION

'.:• Sand

FIGURE 27.—Cross sections showing stratigraphic relations of surficial deposits at locations shown in figure 26. Profiles I and II. Beds 

include Fish House Clay and Philadelphia Blue Clay of others. Beds at Van Sciver Lake include the Cape May Formation of Salisb

(1917) and Gill (1962). This information applies to figures 27-30.
-SPRING LAKE BEDS- -VAN SCIVER LAKE BEDSMETERS XBRIDGETON 

30 —

20 —

10 —

^r / r

PENSAUKEN

PENNSYLVANIA

III—Section from Emilie, Pennsylvania to Bordentown, New Jersey

20-

SEA 

LEVEL

10-

PENNSYLVANIA

———————————SPRING LAKE BEDSIV.—Section at Pennsylvania Turnpike Bridge

-VAN SCIVER LAKE BEDSNEW 

_____

0 400 METERS 

0 1300 FEET

CR

FIGURE 28.—Cross sections showing stratigraphic relations of surficial deposits at locations shown in figure 26. Profiles III and IV. 

explanation.
D34 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES
20

CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA 

PENNSYLVANIA

SPRING LAKE

D35

NEW JERSEY

VAN SCIVER LATE WISCONSINIAN 

LAKE BEDS AND HOLOCENE BEDS

_N,______J^ / ^l

SPRING LAKE 

BEDS .

EXPLANATION

Artificial fill

Water

i_~^~_ Silt-clay

VII.—Section from South Philadelphia, Pennsylvania 

to Red Bank, New Jersey

\ ' BEDS

•••-XPENSAUKEN LATE WISCONSINIAN 

AND HOLOCENE BEDS

NEW JERSEY

VIII.—Section from Port Penn / MIOCENE ROCKS

Delaware to Artificial 

Island, New Jersey

2000 4000 METERS

I 1 I 

0 4000 8000 12,000 FEET

LATE WISCONSINIAN VAN SCIVER LAKE BEDS AND HOLOCENE BEDS 

VAN SCIVER LAKE BEDS

•^Cape Henlopen DELAWARE BAY

IX.—Section from Cape Henlopen, 

Delaware to Cape May, New 

Jersey

I T I 

0 10,000 20,000 30,000 FEET

30 —

40 —

50

60

MIOCENE ROCKS

10,000 METERS

FIGURE 30.—Cross sections showing stratigraphic relations of surficial deposits at locations shown in figure 26. Profiles VII, 

VIII, and IX. Profiles VII-IX modified from Moody and Van Reenan (1967).
D36 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

The distribution is very significant because the northwestern part of Assunpink Creek valley is bounded by a 

high-level (30 m (100 ft) or more) uninterrupted valley 

wall of sedimentary and metamorphic rocks of the Piedmont province. At least part of the sediment of the 

Spring Lake beds at Trenton, therefore, was introduced 

into this region by a large stream flowing from the northeast and not by the Delaware River, a fact noted by Salisbury and Knapp (1917).

Exposures of this unit within Assunpink Valley are far 

and widely scattered; locally, they may be seen along the 

creek, in the bluffs along Spring Lake where the Delaware River cuts across the valley fill of the creek, and in 

railroad and roadcuts in and north of Trenton. Within 

this valley, the fill is as much as 18 m (60 ft) thick but is 

commonly much less. Typically, this formation consists 

of two lithologies—a lower yellow-brown gravelly sand, 

similar to the Pensauken discussed previously, and an 

upper pale-reddish-gray to pale-gray gravelly sand. The 

contact between the two units is sharp, and commonly a 

gravel layer is found along the contact. The thickness of 

each bed varies from locality to locality, but the reddishgray beds are typically the thickest. Salisbury and Knapp 

(1917) and later MacClintock and Johnson (1956) considered the upper bed to be the Cape May Formation and 

the lower bed, the Pensauken Formation. We do not 

agree with these interpretations.

Across the Delaware River in Pennsylvania, sediments in a long, narrow band are similar to and are at

generally the same altitude, nearly 21 m (70 ft), as those 

in the Assunpink Valley (Owens and Minard, 1975). 

These deposits are typically very gravelly (fig. 31A). In 

fact, boulders as much as 14 m (5 ft) across are common 

in many of the pits in this unit. Somewhat farther downvalley, between Florence and Burlington, N.J., these deposits are much sandier (fig. 3L5).

Between Burlington and Palmyra, the width of the 

post-Pensauken valley is less than 3 km (2 miles), and 

deposits referrable to the Spring Lake beds are absent, 

possibly having been removed during the emplacement 

of younger deposits. At Palmyra, the Pensauken (fig. 32) 

is overlain by a channel-shaped deposit of interstratified 

thin beds of cross-stratified sand and grayish-green clay 

(fig. 28, Profile III). These beds, the interstratified sand 

and clay, are downvalley equivalents of the Spring Lake 

beds. A coarse gravelly sand is present at the base of the 

channel (fig. 28). The clay that crops out near the surface 

is dark red, suggesting deep subaerial oxidation of these 

deposits.

To the southwest, the post-Pensauken valley broadens 

again, and near Philadelphia, it is approximately 6.5 km 

(4 miles) wide. Deposits that appear to be correlative 

with those at Spring Lake occur on both sides of the Delaware River at altitudes of 12 to 18 m (40 to 60 ft). The 

largest area underlain by these deposits in this region is 

at Philadelphia, where the deposits are referred to as the

FIGURE 31.—A. Coarse-gravel fades of Spring Lake beds. Pit is at Penn Valley, Pa. B. Sand fades of Spring Lake beds 1.9 km (1.2 miles)

northeast of Burlington, N.J., just north of U.S. Route 130.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D37

FIGURE 32.—Basal gravel of Spring Lake beds overlying Pensauken Formation at Palmyra, N.J. Pit is just west of junction of U.S. Route 130

and U.S. Route 73.

"Philadelphia blue clay." In New Jersey, a small perched 

terrace near Camden was once extensively mined and referred to as the "Fish House Clay" (fig. 29, Profile VI). 

Although the "Philadelphia blue clay" is more widespread than its probable New Jersey equivalent, the 

"Fish House Clay," the latter unit is better known, primarily because of the very detailed study of this deposit 

by Woolman (1897) (see fig. 29, Profile VI). The pits that 

exposed the "Fish House Clay" have been abandoned 

and built over. Part of the deposit remains as indicated 

by the log from an augered hole along the abandoned pit 

edge (fig. 33). The bulk of the deposit is primarily fine 

clasts, silt and clay, green or grayish green, and deeply 

weathered near the surface. The clay is about 9 m (30 ft) 

thick and overlies beds resembling the Pensauken. Similar thick clay-silt layers, overlying Pensauken-type deposits, also occur in the Philadelphia area (Strock, 1929; 

Greenman and others, 1961).

Down valley from here, data regarding the Spring Lake 

beds are very sparse, largely because of poor exposures 

and few detailed studies of the wells that have been 

drilled in this area, or lack of drilling by ourselves. Correlations, therefore, are speculative between Philadelphia and lower Delaware Bay.

In the Port Penn, Del., area (fig. 30, Profile VIII), 

sediments having surface altitudes of 6 to 9 m (20 to 30 

ft) above sea level occur along the edges of the Delaware 

River. These sediments are interpreted to be remnants 

of the Spring Lake beds. Farther south, in the lower Delaware Bay, similar deposits are present, at least on the 

west side of the bay. There, deposits are separated from 

the lower lying deposits by an intermittent scarp that 

has a toe almost 6 m (20 ft) above sea level. Apparently, 

Spring Lake beds were present throughout the present 

Delaware River valley but have been extensively stripped 

away in many parts of the valley.
D38 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

METERS 

BELOW SURFACE

0

6 -

10

Surface: 55 feet (16.7 m) 

Yellow-brown sand, medium-grained

Light-yellow to pale-gray silty clay streaked with 

iron oxides

Orange-brown streaked white silty clay

Light-gray clay with occasional streaks of iron 

oxide, becomes darker gray with depth

Greenish-gray very clayey silt 

Greenish-gray clay with traces of silt

Greenish-gray very clayey silt

Gray very micaceous clayey silt

Gray clay with numerous irregular masses of 

blue vivianite.

Dark-gray clayey silt with small amounts of 

fine-grained sand; extremely micaceous; 

glauconite sand abundant at 28-31 feet (8-9 

m)

Orange-brown clayey silt to clay; abundant 

iron oxides. Pensauken(?) Formation

Yellow-brown sand, medium- to 

coarse-grained, Pensauken(?)

FIGURE 33.—Log of auger hole in "Fish House Clay" on east side 

of River Road, Camden, N. J. For precise location and description of clay pit, see Woolman (1897).

PETROLOGY

The Spring Lake beds are characterized by marked 

textural changes downvalley. At Trenton, the beds are a 

very gravelly graywacke sand. Gravel diminishes in both 

size and concentration downvalley, and the unit is mostly 

interbedded sand and clay-silt. Clay-silt is particularly 

thick in the upper beds near Philadelphia. The sand also 

shows a downvalley change in composition. At Trenton, 

the sand has large concentrations of feldspar. Downvalley, the feldspar content decreases and the sand is mostly 

quartz. This change is possibly the result of two factors. 

One factor is that the rock fragments are less durable 

than quartz during transport downstream. The other factor is that the Delaware passes through a vast width of 

quartz-sand surface beds (Cohansey Sand and Kirkwood 

Formation) that would contribute large amounts of quartz 

to the Van Sciver beds, causing a marked change in

quartz content from the upper to the lower valley. Heavymineral assemblages in the beds follow much the same 

pattern. In the upper valley, the beds have large concentrations of hornblende and pyroxene (immature assemblage). Downstream, the concentrations of these two 

mineral types decline markedly, producing a more mature heavy-mineral assemblage after the change from a 

graywacke to an orthoquartzite in the lower valley.

The clay assemblages in this unit also are less mature 

than the assemblages in the older units, as shown by the 

large concentrations of chlorite and montmorillonite in 

both the clay-silt beds and the clay-silt matrix of the 

sand. Montmorillonite and chlorite are unstable in zones 

of intensive subaerial oxidation. The presence of these 

minerals in the interstices of sands indicates that the 

beds are not extensively weathered.

AGE

, In contrast to the older formations, the Spring Lake 

beds have floral and faunal remains. In the middle upper 

valley near Camden, N.J., marine and freshwater diatoms, sponge spicules, freshwater clams, and vertebrate 

remains (horse, Equis complicatus, and unnamed wolf 

vertebrate) have been reported from these beds (Woolman, 1890; 1897; Pilsbry, 1897; Richards, 1932). In the 

lower Delaware Bay region and along the coast in the 

Delmarva Peninsula, the Spring Lake beds apparently 

interfinger with the estuarine beds and then, farther seaward, with the marginal marine facies of the Omar Formation, which has been dated radiometrically at about 

107,000 years, or Sangamon (B. Szabo, written commun., 1975). The beds at Spring Lake, therefore, are 

Sangamonian in age.

Palynologic studies were made on the dark clayey beds 

at Fish House. As suggested by the marine fauna, the 

overall assemblage is dominated by a warm-temperate 

flora (oak-hickory-birch) and small amounts locally of 

cool elements (spruce and hemlock), particularly near the 

base (L. A. Sirkin, written commun., 1976). The exotic 

pollen types, Pterocarya, Englehardtia, and others, presumably Tertiary forms, are absent; hence, the Spring 

Lake beds contain a modern flora (Quaternary forms).

MODE OF DEPOSITION

The Spring Lake beds have many sedimentary characteristics not observed in the older alluvial units of this 

area. The unit grades from a coarse gravel in the upper 

part of the Delaware Valley at Trenton, N.J., to a sand 

at Burlington, N.J., and finally to a clayey silt at Philadelphia. This textural change takes place within the relatively short distance of 32 km (20 miles). In contrast, 

the older units, particularly the Bridgeton and Pensauken, are largely sand and coarser fragments throughout
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D39

most of their outcrop area—about 160 km (100 miles) in 

both units.

The general arrangement of the various lithofacies in 

the Spring Lake beds resembles, in most respects, the 

depositional environments existing today in the Delaware River valley, particularly between Trenton and 

Philadelphia. At present, the Delaware River upstream 

from Trenton is flowing on bedrock and has a relatively 

steep gradient. Below Trenton, the gradient is low, and 

the river is tidal. Above Trenton, the stream is mostly 

transporting sand and gravel as bedload, whereas below 

Trenton, most of this bedload is deposited because of a 

reduction in gradient, and only the clay-silt clasts are 

transported in suspension downstream. The depositional 

environments in this modern analog, therefore, would be 

fluviatile above Trenton, deltaic at Trenton just below 

the Fall Line, and estuarine where the sand is deposited 

(clayey) from Philadelphia downstream.

The presence of thick clayey estuarine deposits well 

into the upper part of Spring Lake depositional valley 

represents a marked change in environmental conditions 

when this valley is compared with the depositional valleys of the older formations in which sand dominated 

throughout.

The Spring Lake beds, particularly at Trenton, are 

markedly different in physical appearance from those in 

the older gravelly units. Overall they are gray to pale 

reddish brown and lack the widespread cementation and 

staining by iron oxide found in the older, higher level 

units. The similarity of the clay-mineral assemblages in 

both the matrix of the sand and gravel and in the claysilt strata of the Spring Lake beds suggests that these 

beds have not been weathered extensively. Certainly the 

degree of subaerial oxidation in this unit is considerably 

less than that found in the older formations. Several previous investigators recognized the similarity between 

the sediments of the Spring Lake beds and those in the 

morainal deposits to the north. Because of this similarity, many have considered the "Trenton gravel," including the beds at Spring Lake, to be Wisconsinan in age 

(Peltier, 1959). Radiocarbon dating in the lower valley 

and the possibility that the Spring Lake beds may be the 

fluviatile equivalent of the fossiliferous Omar Formation 

at the coast, however, make such an interpretation unlikely. In our study of the coastal deposits in the central 

Delmarva Peninsula, we would correlate this unit with 

the Omar beds (Sangamonian age) of that region. If the 

Spring Lake beds are Sangamonian in age, they probably 

represent in part reworked debris from morainal deposits older than Wisconsinan, that is, Illinoian, or perhaps 

older.

The fossil evidence (marine diatoms, Woolman, 1897) 

supports at least a partial estuarine origin for the clayey 

beds as far upvalley as Philadelphia. The presence of

fresh-water mussels (Woolman, 1897) near the base of 

the clay, then more marine diatoms in the upper part of 

the clay, suggests the gradual encroachment of marine 

conditions up the valley during deposition of this unit. 

This relationship suggests that the deposits accumulated 

during a rise in sea level (transgression). Microfloral remains (principally oak-hickory-dominated pollen assemblages) in the clay indicate that the climate was mild during this transgression, thus attesting to a nonglacial time 

of accumulation.

Figure 34 shows the direction of sediment transport 

during the deposition of this unit. There is no evidence 

that beds of this age are present in southern New Jersey; 

they are, however, found along the west side of Delaware Bay.

VAN SCIVER LAKE BEDS ("GRAYWACKE 1") 

DISTRIBUTION AND LITHOLOGY

In the Delaware Valley at Trenton, a broad terrace as 

much as 8 km (5 miles) wide has surface altitudes of 3 to 

6 m (10 to 20 ft) above sea level (fig. 27, Profile II). The 

terrace crosscuts the higher level Spring Lake beds, dividing this unit into three separate masses (Owens and 

Minard, 1975). The lower part of the terrace is underlain 

by sand and gravelly sand, which have been extensively 

dug in Pennsylvania, producing a large artificial body of 

water called Van Sciver Lake. This site was chosen to be 

representative of these beds, although only one of several lithofacies in this unit is present here. Earlier, this 

deposit was mapped as "Graywacke 1" (Owens and Minard, 1975).

The distribution of this unit is shown in the cross sections in figures 27-30. In the northernmost section (Profile I), up the Delaware River, the Van Sciver Lake beds 

have surface altitudes as much as 12 m (40 ft) above sea 

level, and the base is consistently above sea level. At 

Trenton (see Profiles II and III), the crosscutting relationship to the Spring Lake beds is shown. The base of 

the Van Sciver Lake beds deepens gradually down the 

Delaware Valley (Profiles IV-VIII), and in the vicinity 

of the Cape May airport, the deepest channel in the unit 

extends to about 60 m (200 ft) below sea level (Profile 

IX). The entrenchment into and below the Spring Lake 

beds is shown in this series of profiles.

Exposures of the Van Sciver Lake beds are few because most of the unit is deeply buried. The best outcrops are in excavations in the upper Delaware River 

valley, particularly at Van Sciver Lake. For a short 

time, the beds were exposed in a deep excavation at Artificial Island, N.J. The coarse gravel and sand within 

this unit are somewhat similar to those in the beds at 

Spring Lake. In the upper part of the valley near Trenton, the beds are very gravelly (fig. 35). Downvalley at
D40 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

PENNSYLVANIA

MorrisvilkTX ^Trenton

Philadelphia 7 Fish House 

Camden

—— —— Approximate limit of outcrop of 

Spring Lake beds DELAWARE BAY

Direction of sediment transport 

—Queried where unknown

Cape Henlopen 

Lewes

39° —

FIGURE 34.—Direction of sediment transport during Spring Lake time. Sediment entered the Trenton area from the northeast and

moved down present Delaware Valley to the sea.
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D41

FIGURE 35.—Typical lithology in cut banks at Van Sciver Lake 2.7 km 

(1.7 miles) due south of Morrisville, Pa.

Artificial Island, the gravel content has declined, and the 

unit is mostly interbedded, thick-bedded clay-silt (fig. 

36) and crossbedded sand (fig. 37). Figure 38 is a measured section in the pit, showing the various lithologies 

in this unit. The interbedding of sand and clay-silt persists to the coast (fig. 30, Profile IX), where, however, 

the unit is fossiliferous (Gill, 1962). Here we included the 

Cape May Formation of Gill (1962) in the Van Sciver 

Lake beds.

Figure 39 shows the direction of sediment transport in 

this unit within the area of investigation. The sediment 

in this unit at Trenton was introduced in the Delaware 

Valley from the northwest, as shown by the map distribution (Owens and Minard, 1975). This direction thus 

represents a significant change from the direction of sediment input of the older units in the valley. Downvalley 

from Trenton to Salem, the Van Sciver Lake sediments 

underlie much of the lower lying parts of the valley. 

From Salem to Cape May, these sediments appear to be 

largely restricted to the east side of Delaware Bay.

Because of their restriction to the Delaware Valley 

and because of poor exposures, no effort was made to 

study the crossbedding, hence vectoral properties, in 

this unit.

PETROLOGY

As observed earlier, the sediments in this unit and in 

the Spring Lake beds are lithologically very similar in

FIGURE 36.—Massive dark-gray clay-silt underlain by thin coarse 

gravel bed at base of channel in excavation at Artificial Island, N.J. 

Vincentown Formation (Paleocene) is exposed at base of bank.

FIGURE 37.—Large-scale high-angle crossbeds in sands near base of 

excavation at Artificial Island, N.J.

outcrop to those in the upper part of the valley. Downvalley samples were available at only a few localities (Artificial Island and Cape May Peninsula, N.J.). The mineralogy of the sediments in this unit therefore is only 

grossly known.

On the Pennsylvania-New Jersey border, at and in the 

vicinity of Van Sciver Lake and upvalley to Scudders 

Falls, the sand in this unit is a high-rank graywacke as 

defined by Krynine (1948). The gravel (fig. 35) also is 

characterized by a large number of rock types, conspicuous among which is limestone. Mostly, however, the
D42 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

Top of cut bank, 11 feet (3.3 m) above sea 

level. Finely laminated clays and silts. 

Form long continuous beds. Dark gray 

throughout

Pale-brown sand with small worn shells. 

Thin layers of very carbonaceous "hash" 

scattered throughout. Probable artificial 

fill

Dark-gray clay with thin laminae of very fine 

sand. Carbon-14 date on wood 6330 

radiocarbon years, (W-2324)

Thinly bedded dark-gray silts and clays 

interbedded with light-brown sands. 

Sands cross-stratified. Possible artificial 

fill from dredged channel adjacent to 

island

/Pale-green interbedded silts and fine-grained 

sands. Cross-stratified, small-scale troughs

^ark-gray massive clay, abundant 

carbonaceous matter. Carbon-14 date 

>40,000 radiocarbon years, (W-2296)

Sandy gravel; maximum gravel size 2 inches 

(5.08 cm)

Dark-gray very clayey silt with abundant 

finely dispersed carbonaceous matter, 

pieces of gravel to 1 inch (2.54 cm) 

scattered throughout. Carbon-14 date on 

wood >42,000 radiocarbon years, (W-2266)

vSandy gravel, maximum size gravel 2 inches 

(5.08 cm)

Pale-green sand, medium grained, mostly 

with small pieces of wood disseminated 

throughout. Basal beds reddish to orange 

brown. Extensively cross-stratified, 

large-scale planar beds

Dark-gray to black silty clay to clayey silt, 

somewhat sandy. Abundant 

carbonaceous matter, mostly finely 

dispersed but with large coalified logs

Pale reddish-brown sand with roots 

projecting from above. Based with a gravel, 

maximum size gravel 2 feet (0.6096m)

Calcarenite, Vincentown Formation 

(Paleocene)

FIGURE 38.—Composite section from deep excavation at Artificial Island, N.J.

calcareous material forms coatings on the more siliceous 

gravel pieces. At Artificial Island, the sand has a much 

lower proportion of rock fragments, and the quartz content increases markedly. The interbedded clay-silt has a 

veried clay-mineral assemblage characterized, as in the

Spring Lake beds, by a high concentration of chlorite. On 

the Cape May Peninsula, the beds assigned to this unit 

are very quartzose, essentially protoquartzite in composition.

The nonopaque heavy minerals do not vary greatly 

throughout the valley. At all localities sampled, the nonopaque heavy minerals are immature, containing moderate amounts of hornblende and to a lesser degree, hypersthene.

AGE

The beds at Van Sciver Lake are considered to be Sangamonian in age on the basis of the following facts. The 

fossils in this unit at Cape May are in part a warm-water 

assemblage (Richards, 1962). The pollen in the deposits 

at Artificial Island and in the clay-silt beds at Cape May 

consists of similar warm-temperate assemblages (L. A. 

Sirkin, written commun., 1975). Radiocarbon ages run 

on shells from Cape May were greater than 35,000 radiocarbon years (Richards, 1962). Wood from the undisturbed beds at Artificial Island yielded ages of greater 

than 40,000 radiocarbon years (W-2266 and 2296). All 

these data are compatible with deposition during an interglacial period. These facts taken in conjunction with 

the crosscutting relationship of this unit with Spring 

Lake beds, also thought to be Sangamonian, suggest a 

late Sangamonian age for the beds at Van Sciver Lake. 

These beds would correlate with the Ironshire Formation of the central Delmarva Peninsula (Owens and 

Denny, 1978).

MODE OF DEPOSITION AND ORIGIN

The distribution of sediment in this unit is somewhat 

similar to that in the Spring Lake beds. Basically, the 

deposits in the Van Sciver Lake beds are more gravelly 

in the upper part of the valley and more clayey in the 

lower part. In addition, the sand changes from immature 

(graywacke) in the upper part of the valley to mature 

(protoquartzite) in the lower part. Gill (1962) in his analyses of the beds at Cape May noted that estuarine beds 

were at the base and marine beds at the top. Such a relationship suggests an initial period of downcutting and 

then an infilling of the valley, first by sediments laid 

down under brackish conditions and then by sediments 

deposited under open-ocean marine conditions. The vertical arrangement of beds indicates a regression followed 

by a transgression. The regression was of large magnitude, extending to more than 60 m (200 ft) below sea 

level at the present coast. Sea level then rose to nearly 

7.4 m (25 ft) above the present level, or somewhat less 

than the sea-level rise associated with the beds at Spring 

Lake (nearly 21 m (70 ft) above present sea level).

If these relationships are valid, then the Van Sciver
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA

75°

D43

Limit of outcrop of Van Sciver 

Lake beds

Trend of paleocurrents 

—Queried where unknown

39° —

FIGURE 39.—Hypothetical paleocurrent trends in the beds at Van Sciver Lake, Pa.
D44 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

Lake beds represent a single regressive-transgressive 

cycle and are not associated with the sedimentary cycle 

represented by the Spring Lake beds. Open-ocean marine conditions did not extend very far up the Van Sciver 

Lake beds valley, as evidenced by no marine fossils at 

Artificial Island, N.J., and none reported in the many 

borings into this unit even farther up the valley. The marine phase of the Van Sciver Lake beds has a very restricted distribution to the lower Delaware Bay region. 

The marine incursion up the Delaware Valley was less 

during Van Sciver Lake time than during Spring Lake 

time.

SUMMARY

The original plan of our study was to examine the surficial sediments of the "Amboy-Salem" trench or valley 

along the inner edge of the New Jersey Coastal Plain. As 

the study progressed, the scope of the investigation had 

to be enlarged to cover southern New Jersey and the 

northern half of the Delmarva Peninsula west of Delaware Bay in order to understand the regional stratigraphic relationships within these alluvial sediments.

The "yellow gravels" of Salisbury (1898) were critically analyzed to determine whether mappable units 

were indeed present, as Salisbury and Knapp (1917) proposed, or whether, as MacClintock and Richards (1936) 

had proposed, the "yellow gravels" were a single sedimentary complex spanning most of early Pleistocene 

time. Although the "yellow gravels" are lithologically 

very similar (largely sand and gravelly sand of arkosic 

composition), viewed regionally, two distinct gravelly 

sand sheets were outlined—the older and higher level 

beds (the Bridgeton), largely in southern New Jersey, 

and the lower level beds (the Pensauken), mostly in the 

northern Delmarva Peninsula (fig. 40). These two units 

occupy part of the Amboy-Salem trench or valley between Trenton and Salem, N.J. Here, the Bridgeton is 

found typically on hilltops, surrounded by Pensauken in 

the adjacent valleys. The Pensauken appears to have 

been deposited in valleys that eroded through the Bridgeton and thus postdates this unit.

This interpretation differs from that of Salisbury and 

Knapp (1917). In their interpretation, the Bridgeton 

would have been restricted largely to southern New Jersey, and the Pensauken would have occupied nearly all 

the Amboy-Salem trench. In this general region, we 

would restrict the Pensauken to the Swedesboro plain 

(New Jersey) of Salisbury and Knapp (1917), and the 

Woodstown plain deposits (New Jersey) to the Bridgeton.

Crossbedding studies within the Bridgeton and Pensauken Formations reveal that both units occupied at 

least parts of the Amboy-Salem trench northeast of

Bridgeton Formation

Pensauken Formation

Spring Lake and Van Sciver Lake beds

Upper Pleistocene and Holocene, largely 

Chesapeake and Delaware Bay fill

Approximate limit of glacial deposits 

Approximate limit of outcrop of units 

—Queried where doubtful

STATEN ISLAND 

oodbridge

FIGURE 40.—Map showing locations and shapes of the different units 

in the area of investigation.

Trenton. The Bridgeton sediments were carried into the 

New Jersey Coastal Plain by a large stream coming from 

the north (the ancestral Hudson?), but the evidence for 

the most northeasterly extension of the stream is buried 

beneath a thick covering of glacial deposits of Pleistocene 

age. The upvalley distribution of the Pensauken was not 

investigated, but the deposits discussed by Hale and 

Howell (1946) and Campbell and Bascom (1933) in the 

vicinity of Somerville, N.J. or well to the north of the 

Amboy-Salem trench, may be the Pensauken. In any 

case, the sediments of both formations occupy the same 

part of the valley southwest from Trenton to near Clementon, where the crossbedding direction in the Bridgeton sediments turns sharply to the east. Studies of the 

Bridgeton crossbeds in southern New Jersey reveal that 

the gravel sheet was constructed by a series of channels
CENOZOIC SEDIMENTS OF DELAWARE VALLEY AND DELMARVA PENINSULA D45

downcutting from north to south. Studies of the 

crossbedding in the Pensauken gravel sheet largely east 

of Chesapeake Bay reveal that this unit was also constructed by a series of channels downcutting from northeast to southwest, or nearly at a right angle to the downcutting direction of the Bridgeton channels in southern 

New Jersey. Both these gravel sheets, therefore, were 

formed by essentially the same mechanism as that proposed by Hack (1955) for the upland gravels sheet of the 

"ancestral" Potomac River in southern Maryland.

No datable fauna or flora have ever been recovered 

from the Bridgeton, but, as discussed by Owens and 

Denny (1978), the Pensauken coarse clasts interfinger 

with deltaic marginal marine units in the subsurface of 

the southern half of the Delmarva Peninsula. These marginal marine (deltaic) units (the "Yorktown and Cohansey?" Formations as used by Rasmussen and Slaughter 

in 1955) have been dated as latest Miocene. In our view, 

therefore, the Pensauken and thus the Bridgeton are not 

Pleistocene in age but are considerably older. The Bridgeton is post-Cohansey (the Cohansey of New Jersey, 

which must be at least Miocene) and is older than the 

Pensauken (upper Miocene); it must therefore be some 

part of the Miocene, possibly upper. This greater age is 

probably the reason for the very weathered appearance 

and lateritic soil of these two formations.

The "Trenton gravel" of Lewis (1880) is lithologically distinct from the deeply weathered Bridgeton and 

Pensauken Formations. The sediment in this unit is 

much fresher and shows comparatively little evidence of 

subaerial oxidation. A twofold division of the "Trenton 

gravel" near Trenton is proposed: (a) the Spring Lake 

beds, at altitudes as great as 21 m (70 ft) above sea level; 

these deposits were introduced into this area from the 

northeast and therefore not along the present segment 

of the Delaware River flowing from the northwest; and 

(b) the Van Sciver Lake beds, which have surface altitudes at approximately 6 m (20 ft); the sediments in these 

beds were transported into the Trenton area from the 

northwest along the present Delaware River. Both these 

units have similar facies relationships—coarse gravelly 

sand in the upper part of the valley that grades rapidly 

downvalley to finer clasts characterized by abundant 

finely dispersed carbonaceous matter. This downvalley 

fining of the sediment in these beds is a marked departure in sedimentation pattern from that of the Bridgeton 

and Pensauken Formations, where sand predominated 

over vast areas. Certainly, the sheet gravels characteristic of the older formations are absent in the two units 

of the "Trenton gravel." As interpreted, a rapid sealevel drop initiated downcutting, and both these units 

were deposited as valley infillings during a subsequent 

rise in sea level. The deposition of these Sangamonian

beds of the "Trenton gravel," therefore, seems to conform with the theory of a late Wisconsinan drop of sea 

level and the subsequent infilling of the formed river valleys during a Holocene rise in sea level in Chesapeake 

and Delaware Bays (Owens and others, 1974).

The problem, therefore, is what event or events are 

represented by these two units in the "Trenton gravel." 

The very heterogeneous character of the sediment in 

these units suggests the contribution of rocks from many 

sources. Several other investigators have noted the general similarity of the sediments in these beds at Trenton 

to those in the glacial deposits of northern New Jersey 

and have interpreted the "Trenton gravel" to be reworked sediment from these glacial deposits. The higher 

level deposits (Spring Lake beds) appear to have been 

introduced into the Trenton area from the northeast by 

a stream system no longer in existence. Certainly the 

present stream is too small to account for the quantity 

and size of the material in the Assunpink Creek valley in 

the area north of Trenton. In addition, these sediments 

can be only traced a relatively short distance (11 km; 7 

miles) northeast of Trenton and certainly not to the Wisconsinan moraines near New Brunswick, N. J. A possible 

interpretation is that the Spring Lake beds are reworked 

sediment from pre-Sangamonian glacial deposits. Although these deposits have been reported (Minard and 

Rhodehamel, 1969) in New Jersey south of the terminal 

moraine, they are very poorly known. Downvalley from 

Trenton, the gravel in this unit decreases, and in the 

Philadelphia-Camden area it is overlapped by a thick sequence of dark clay-silt (the "Philadelphia blue clay" in 

Pennsylvania and the "Fish House Clay" in New Jersey). These beds probably are the estuarine facies associated with a Sangamon sea-level rise to about 12 m (40 

ft) and perhaps as high as 18 m (60 ft) above sea level 

during this time. Numerous fossils in these beds support 

an estuarine origin but could not be used to date the deposits. At the coast, beds of this unit have more marine 

aspects and contain a warm-temperate flora (the Omar 

Formation of Owens and Denny, 1978). The fossil assemblage is considered to be probably late Pleistocene in 

age. Shells within this unit that were dated by the radiocarbon method were too old to yield a finite age (therefore, the unit is probably older than 38,000 years B.P.). 

This age taken in conjunction with the warm flora, and 

presumably a warm-water fauna, suggests a Sangamonian or older age.

The Van Sciver Lake beds are lithologically similar to 

the higher level deposits at Spring Lake but appear to be 

at consistently lower levels throughout the area of investigation. The sediment in this unit appears to have been 

introduced into the Trenton area down the present Delaware Valley (northwest) and thus establishes the time
D46 GEOLOGIC STUDIES IN EMERGED COASTAL PLAIN OF MIDDLE ATLANTIC STATES

when this segment of the river became the major sediment drainageway for the river. Downvalley, these sediments downcut through the Spring Lake beds and ultimately interfinger with marine and marginal marine 

fades, the Cape May Formation of Gill (1962). The Van 

Sciver Lake beds are considered to be late Sangamonian 

in age and equivalent to the Ironshire Formation of the 

lower Delmarva Peninsula (Owens and Denny, 1978).

Both the Spring Lake and Van Sciver Lake beds represent separate transgressive-regressive cycles. Thus, 

in the Sangamon, there is evidence of two periods of sealevel drop followed by a rise. Although the Spring Lake 

beds might be an older Pleistocene unit (Illinoian?), they 

are probably early Sangamonian in age.

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