DEPARTMENT OF THE INTEKIOR

BULLETIN

OF THE

UNITED STATES

GEOLOGICAL SURVEY

Xf^jLOfilC/i

/=b'3

67

THE RELATIONS OF THE TRAPS OF THE NEWARK SYSTEM 

IN THE NEW JERSEY REGION

WASHINGTON

GOVERNMENT PRINTING OFFICE

1890

203(222)

326
LIBRARY CATALOGUE SLIPS. - r t

United States. Department of the interior. ( U. S. geological survey). 

Department of the interior } | Bulletin | of the | United 

States | geological survey | no. 67 | [Seal of the department] | 

Washington | government printing office | 1890

Second title: United States geological survey | J. W. Powell, 

director | | The relations | of the | traps of the Newark system | 

in the | New Jersey region | by | Nelson Horatio Darton | [Vignette] |

Washington | government printing office | 1890

8°. 82pp. 6 pi.

Darton (Nelson Horatio).

United States geological survey | J. W. Powell, director | | 

The relations | of the | traps of the Newark system | in the | New 

Jersey region | by | Nelson Horatio Darton | [Vignette] |

Washington | government printing office | 1890

8°. 82 pp. 6 pi.

[UNITED STATES. Department of the interior. (V. S. geological survey). 

Bulletin 67]. 

United States geological survey | J. W. Powell, director | | 

The relations | of the | traps of the Newark system | in the | New 

Jersey region | by | Nelson Horatio Darton | [Vignette] j

Washington | government printing office | 1890

6°. 82 pp. 6 pi.

(UNITED STATES. Department of the interior. (TJ. S. geological survey). 

Bulletin 67].

[Bulletin No. 67.]

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To THE DIRECTOR OF THE

UNITED STATES GEOLOGICAL SURVEY,

WASHINGTON, D. C. 

WASHINGTON, D. C., November, 1890.

DEPARTMENT OF THE INTERIOR

BULLETIN

THE

D STATES

GEOLOGICAL SURVEY

No. 67

WASHINGTON

GOVERNMENT PRINTING OFFICE

3LS90

US. GEOLOGICAL SURVEY BULLETIN No. 67. PL 1.

GK OIX) GIC AI, MAP

OF PART OF

NORTHERN NEW JERSEY

AND ADJACE-XT PORTTOXS OK

NKW YORK AND PENNSYLVANIA

N K I, S () X H . D AR T O N

PALK07.0IC ARCHEANT 

and

METAM'ORPHIC I? I

nlrusm- Traps Extrusive Traps Sediments S hales M.inicsimirs
3(>>

UNITED STATES GEOLOGICAL SUEVEY

J. W. POWELL, DIEECTOR

THE

TRAPS OF THE STEMIN THE

NEW JERSEY REGION

NELSON HOKATIO DARTON

WASHINGTON

GOVERNMENT PRINTING OFFICE

1890

CONTENTS.

PageLetter of transmittal........................................'.............. 11

Introduction.............................................................. 13

Watchung trap sheets..................................................... 16

Structural relations in the-Watchung region........................... 16

Mutual relations of the Watchung traps............................... 18

First and second Watchung traps........................................ 19

General relations................................................... 19

Thickness Faults ...... .......... ................................ 21

Columnar structure ............................................... 23

Succession of sheets.................................. ............. 24

The surface of the trap sheets and their contact relations with the

inclosing strata................................................. 25

Third Watchung trap ................................................. 32

General relations ................................................. 32

Thickness ......................... ............................... 33

Rock structure...................................... .............. 34

Relations to the associated sedimentary rocks....................... 34

New Vernon trap.......................................................... 34

New Gennantown trap.................................................... 36

Palisade trap ............................................................. 37

General relations.............................. .................... 37

Structural relations in the palisade region ......................... 39

Faults ............................................................ 41

Thickness......................................................... 44

Relations to underlying strata ..................................... 45

Relations to overlying strata...... ................................ 50

Union Hill trap ........................................................... 53

Granton trap.............................................................. 54

Snake Hills trap ..........................;............................... 55

Arlington traps ........................................................... 56

Lawrence Brook, Ten Mile Run Mountain, Rocky Hill, Pennington Mountain, Bald Pate, and Jericho Hill traps ................................... 59

Sourland Mountain trap ......................................:.......'..... 61

Trap of Cushetunk and Round Mountains ................................. 62

Small trap sheets in the Raritan River region ........................ ..... 65

Martin's Dock..................................................... 65

New Brunswick................................................... 66

Fleraington.......................... ...... ....................... 66

W.ertsville................ ........................................ 67

Neshanic ...................................................T..... 67

Smaller trap masses of the Delaware River region ......................... 68

Point Pleasant..................................................... 68

Belle Mountain ...................................................... 68

Brookville........................................................ 69

, 5
6 CONTENTS.

Small dikes ............................................................... 69

Blackwell's mills.................................................. 69

Hackeusack ................................................ ...... 70

South Branch..................................................... 70

Three Bridges.:.................... ............................... 70

Stanton station ................................................... 70

Summary................................................................. 70

Bibliography ............................................................. 74

Index ........................................ .... ...................... 80
ILLUSTRATIONS.

Page. 

PLATE I. '(Frontispiece.) Geologic map of part of northern New Jersey and

adjacent portions of New York and Pennsylvania. 

II. Map of a portion of northeastern New Jersey, showing the relations of the Watchung traps .................................. 16

III. Sections across the Watchung traps along the lines shown on

PI. II......................................................... 18

IV. Map of the region adjacent to the New Vernon trap, Long Hill, 

and the inner side of the terminal hook of the second Watchung 

Mountain..................................................... 34

V. Lateral ascent of the base of the palisade trap across edges of 

strata in King's Point, Weehawken, New Jersey. Looking west. 

From panoramic photograph................................... 46

VI. Map of the Delaware Eiver region .............................. 62

FIG. 1. Section through Paterson, New Jersey. Looking north.......... 18

2. Sections illustrating the stratigraphy of the Watchung region

along the section lines shown in Plates II and III............... 21

3. Cross-section exposure iu the end of the front edge of the first 

Watchung trap at Garret Kock, south of Paterson. Looking 

south.................. ...................................... 23

4. Section at Bernardsville station, showing superposition of trap at 

the termination of the Second Watchung Mountain. Looking 

southwest .... ............................................... 24

5. Section along road on southeastern shore of Pompton Lake, showing portion of vesicular beds in the second Watchung trap. Looking southwest................................................. 25

6. Section showing relations of surface of first Watchung trap, and 

its contact with overlying strata, along south side of gorge, just 

northeast of Feltville, N. J. Looking south ................... 27

7. Section of breccia immediately below base of first Watchung trap

in American copper mine near Somerville, N. J................. 29

8. Cross-section exposure of edge of first Watchung trap lying on 

sandstones on the south side of the Passaic River, just below the 

 Great Falls, Paterson. Looking south ........................ 30

9. Contact of second Watchung trap with underlying sandstones

in quarry on north side of the Passaic River below Little Falls. 31

10. Supposed tuff and scoria beds overlain and penetrated by the columnar trap at the edge of the second Watchung sheet on the north 

side of the Passaic River half a mile below Little Falls. Looking northwest................................................. 32

11. Section from west of New Germantown to the crest of the second

Watchung Mountain, northeast of Pluckamin. Looking north... 35

12. Map of the New Germantown trap region........................ 36

7
8 ILLUSTRATIONS.

Page.

FIG. 13. Section showing the structure of the palisade trap along the line 

of the West Shore Railroad, in the tunnel and cuts west of Weehawken, N. J. Looking north................................ 37

14. Section similar to the preceding, but three miles south of Haverstraw, New York. Looking west.............................. . 37

15. The Palisades of the Hudson, opposite Hastings, N. Y. From a

photograph................................................... 38

16. Map of Rocklaud County, N. Y ................................... 40

17. Cross-section near Ladentown, N. Y. Looking north............. 41

18. Section across the palisade trap in Bergen Hill, Jersey City. Looking north. .................................................... 42

19. Cross-section, north of Weehawken, N. J., at H C., on Fig.

21. Looking north ............................................ 43

20. Lateral descent of base of palisade trap across edges of strata

north of Hobokeu, N. J. Looking northwest................... 44

21. Map showing the relations of the palisade trap north and northeast of Hoboken, N. J ......................................... 45

22. Contact of trap and indurated shales in entrance to West Shore

Railroad tunnel, Weehawken, N. J. Looking south............ 46

23. Dike in arkose below the quarries at Guttenberg, N. J. Looking

northwest ................ ............ ............ ............ 47

24. Lateral ascent of the base of the palisade trap across edges of

strata, two miles north of Nyack, N. Y......................... 48

25. Trap sheet in arkose under palisade trap, on shore of Hudson River,

four miles south of Haverstraw, N. Y. Looking west.......... 49

26. Exposure of back of dike of palisade trap in cut at southern entrance to West Shore Railroad tunnel, three miles south of Haverstraw, N. Y. Looking west.................................... 51

27. Exposure of back of dike of palisade trap in the cut at western entrance to West Shore Railroad tunnel between New Durham 

and Weehawken, N. J. Looking north......................... - 52

28. Section across Union Hill, northeast of Suffern, N. Y. Looking

north..... .................................................... 53

29. Map and sections showing relations of Granton trap to Palisade trap 54

30. Stereogrammic map and sections of Snake Hill, N. J.............. 55

31. Partial cross-section at one time exposed in western side of Snake

Hill showing the back of the dike. Looking north ............. 56

32. Map of the region near Arlington and the Schuyler Copper Mine,

north of Newark, N. J ......................................... 57

33. Cross-section, at A on Fig. 32, in Westlake's quarry. Looking north 57

34. Cross-section of trap outcrops in the cemetery at Arlington, N. J.

AtBonFig.32. Looking north.............................. 58

35. Fault exposed in cut for New York and Greenwood Lake Railroad,

west of Arlington, N. J. Looking north....................... 58

36. Section through Rocky Hill at gap of Millington River, across to

Sourland Mountain. Looking northeast....................... 59

37. Map of Rocky Hill, Ten Mile Ran Mountain, Lawrence Brook trap

and vicinity .................................................. 60

38. Section along the northeast side of the Delaware River from Titusville to Stockton, N. J ........................................ 61

39. Section across Sourland Mountain from Ringoes to Snydertown,

N. J.......................................................... 62

40. Stereogrammic map and sections of Cushetunk and Round Mountains and vicinity,New Jersey.................................. 63
ILLUSTRATIONS.

Page. 

FIG. 41. Contact of Cnshetunk trap and Cambrian (?) limestone near Prescott Brook, two"miles east of Allentown, N. J. Looking north. 64

42. Cross-sectiou exposure of trap sheets aloug the Raritan River near

Martin's Dock, New Jersey. Looking north .... ............. 65

43. Map of Flemington, N. J., and vicinity, showing the extent and

position of the three trap masses ............................. 66

44. Trap sheet just east of Wertsville, crossing road to Stoutsburg.

Looking north ................................................ 66

45. Cross-section exposures of trap sheet in railroad cut half a mile

west of Neshanic, N. J......................................... 67

46. Cross-section showing the relations of the Point Pleasant trap at

Byram, New Jersey. Looking northeast....................... 68

47. Trap dike in bank of canal two miles south of East Millstone, N. J.

Looking northeast ..............:............................. 69

48. Trap sheet or dike two miles east of Hackensack, N. J. Looking

north............................................. ............ 70

49. Trap dike in shales near South Branch, N. J. Looking east ...... 70

LETTER OF TRANSMITTAL.

UNITED STATES GEOLOGICAL SURVEY, 

APPALACHIAN DIVISION OF GEOLOGY,

Washington, D. 0., April 17, 1889.

SIR : I have the honor to transmit herewith a paper by Mr. Nelson H. 

Darton, assistant geologist, on the relations of the traps of the Newark 

system in ihe New Jersey region to the sedimentary rocks. The field 

work on which the paper is based was chiefly executed as a personal 

enterprise previous to Mr. Darton's connection with the Geological 

Survey, but a few weeks were also spent in revisionary work under the 

auspices of the Survey.

Very respectfully, your obedient servant,

G. K. GILBERT, 

Geologist in charge.

'Ron. J. W. POWELL,

Director.

11

THE RELATIONS OF THE TRAPS OF THE NEWARK SYSTEM IN 

THE NEW JERSEY REGION.

BY NELSON HORATIO BARTON.

INTRODUCTION.

This contribution is a summary of the more complete results of a systematic study of the relations of the Newark system in New Jersey and 

New York.

In commencing field work in 1882 it was my intention to elaborate a 

monographic investigation of the Newark system of the eastern United 

States and the scope ultimately adopted involved a study of all details 

that might throw light on the genesis and structural relations of the 

formations, but owing to a variety of circumstances more or less unavoidable, the work was abandoned after several seasons of intermittent fieldwork extending over the entire New Jersey and New York areas.

In reviewing the results of this incomplete investigation it was found 

that comparatively little new light was thrown on the stratigraphy, 

structure, or genetic relations which would admit of generalization and 

only a multitude of heterogeneous details could be presented in this 

connection. The descriptions by Eogers, Cook, Russell, and others 

give an adequate general idea of the character and distribution of the 

sedimentary rocks, to which I could add little of special interest, but 

the trap masses had not as yet been described in detail, excepting in 

isolated localities, and it seemed probable that an account of their 

structural relations would prove an acceptable contribution.

In studying the structure of the formation much important information was gained, but as this was mainly in regard to the region of the 

trap areas, it was found possible to present it in greater part without 

extending the memoir beyond a description of the relations of the 

igneous rocks.

The traps of the New Jersey Newark region are the most prominent 

features in its topography, the larger masses constituting high ridges 

rising abruptly from the surrounding plains, and generally presenting 

escarpments or steep slopes eastward and gentler slopes in the opposite 

direction towards the dip of the inclosing strata. The more conspicu13
14 . - TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

ous outcrops have long attracted attention, and their igneous nature 

was recognized by the first observers. The first scientific description 

was by Pierce in 1819, but he did not express an opinion in regard to 

their origin, and simply termed them " greenstones." Akerly, in 1820, 

discussed the nature of the Palisade and Newark Mountain rocks, and 

although his discussion and conclusions were vague, he evidently held 

the opinion that they represented old lava-flows. Cooper, in 1822, described the occurrence of columnar and amygdaloidal "basalt" at the 

falls of the Passaic, and considered the rock of Newark Mountains, and 

by analogy the other trap masses of the State, to have been poured out 

over the sandstones; but, as suggested by Davis, he does not appear to 

have had in mind the possibility of intrusion. In 1836, and again in 

1840, Rogers described the relations of the traps, and the actual or supposed alteration in the associated strata, and considered them intrusive and dike-like throughout.

In 1843 Mather described some of the relations of the.palisade trap 

in New York, and called attention to the irregularities in contact and 

to the altered strata at its base, but considered the Palisades, and by 

analogy the other ridges iu New Jersey, due to ancient lavas u that have 

flowed through rocky fissures in dikes while this portion of the continent 

was still beneath the waters of the ocean."

In 1846 Emrnons described the relations at the base of the palisade 

trap at the State line, and stated that the rock was intruded in sheets 

in the sandstone, being the first to definitely recognize its true relations.

In the " Geology of New Jersey," 1868, Cook described the traps at 

considerable length, and although the structural relations are not discussed in detail, the prevailing sheet structure is recognized, and the 

rocks were all considered intrusive. In succeeding reports up to 1886, 

Cook remained unchanged in this opinion of their intrusive nature, and 

for the Watchung traps advanced as evidence, the occurrence of indurated shales and limestones on the back of the mountain, northwest 

of Plainfield (Feltville 1?), and their analogy in general relations to the 

palisade and ether unquestionably intrusive traps.

Eussell, in 1878, described in some detail the occurrence of what were 

then supposed to be intensely altered shales and limestone at Feltville 

and added great weight to the prevailing view that the Watchung and 

all the other trap masses were intrusive. In 1882 Davis visited several 

typical localities in the New Jersey area for the purpose of determining 

the nature of the traps, and while he agreed with previous observers, 

Emmons, Cook, Creduer, and Russell, in regard to the intrusive nature 

of the palisade trap, he stated his conviction that the Watchung traps 

were extrusive and similar in relations to some of the extrusive sheets 

which he had studied in the Connecticut valley. He found the base of 

the second Watchung trap resting on apparent tuff deposits at Little 

Falls; the conformable base and the amygdular and ropy-surfaced rock
DAUTON.] INTRODUCTION. 15

of the first Watchung trap exposed near Paterson. At the Feltville 

locality he found no traces of the alteration described by Eogers, Cook, 

and Kussell, but, on the contrary, it was seen that the vesicular, slag-like 

rock was overlain by unaltered shales with an intervening trap breccia 

at some points. This breccia alone was considered satisfactory proof of 

the extrusive nature of the sheet and he stated his opinion that it could 

only have been formed on the surface of a preexistent sheet of lava.

Studies extending over the entire Watctiuug area confirm Davis's suggestions, and in this memoir it will be shown that all the trap outcrops 

inclosed by the Watchung Mountains, and the outlying mass near New 

Germantown are lavas, contemporaneous with the inclosing sediments^ 

while all the other traps described are intruded sheets and dikes.

The igneous rocks of the New Jersey region are remarkably uniform 

petrographically, as they are all basalts varying mainly in structure and 

development. The eruptives are fine grained and generally somewhat* 

glassy, and the intrusives are coarser grained, generally being doleritic, 

in some cases including considerable biotite and often near gabbro in 

structure.

* Excepting in some few special instances in this memoir, but limited 

reference is made to previous descriptions of general features of topography, structure, etc., as they are indicated in full in the appended 

bibliography, but endeavor is made to give due credit for all observations of important details or discussion of relations by giving the author's 

name, and if necessary the date, so that the remaining information may 

be readily found in the bibliography.

The accompanying colored map is not very different in a general way 

from the maps issued with Cook's reports for 1881 and 1882, but the base 

is from a tracing of the very accurate, large scale topographic maps of 

the New Jersey survey, on which the field work was based and the 

boundaries were carefully plotted. Beside this, the map is extended 

into New York, the dikes and smaller masses are shown and modifications are made in the trap and border boundaries to accord with facts 

determined by the writer's field work. The most noticeable change in 

the position of the formation boundary is between Clinton and Perfyville to exclude the slates which crop out prominently in the Lehigh 

Valley Bailroad cuts and underlie the Newark rocks unconformably.

In conclusion, I have to acknowledge my obligations to those who 

have aided in the prosecution of the investigation. To Prof. George H. 

Cook, State geologist of New Jersey, I am greatly indebted for advice 

and aid, for without his kind help the attainment of the present results 

would not have been possible.

Mr. Frank Marshall Smith has served as field assistant throughout 

the work and his efficiency merits my warmest praise.

To Mr. J. S. Diller and to Mr. Whitman Cross I am indebted for information in regard to the petrography of the igneous rocks of the region.
16 TRAPS OF THE NEW JERSEY REGION. (BULL. 67. 

WATCHUNG TRAP SHEETS.

In the western half of the Newark area, in northern New Jersey, is 

a series' of trap outcrops, of which the Watchuug or Orange Mountains are the largest and most prominent. These outcrops are the 

edges of long, thick sheets of lava, which were successively outpoured 

during the deposition of the Triassic clays and muds, deeply buried in 

subsequent deposits and uplifted and flexed in the post-Newark deformation. Profound erosion has since removed a great thickness of 

these sedimentary rocks, and the outer edges of the lava sheets are 

now exposed, forming prominent elevations above the plains of the 

inclosing, softer materials. Although deeply decomposed, eroded, and 

glaciated, these trap sheets present all the usual evidences of contemporaneous extrusions. Their more or less vesicular bases lie conformably on unaltered or but slightly altered strata; their upper surfaces are 

deeply vesicular; they present evidence of successive flows in part 

on tuft deposits, and they are overlain by unaltered strata ; in one instance with a trap breccia intervening.

STRUCTURAL RELATIONS IN THE WATCHUNG REGION.

As shown in PI. II, the region is characterized structurally by a long, 

shallow, irregular trough or synclinal, prominently defined near its 

broad ends by the curved and recurved terminations of the Watchung 

Mountains.

With the exception of some narrow, marginal crumples, this is the 

only well marked flexure in the New Jersey area, and it materially decreases the width of the general northwest monocline of the formation 

nearly to tlie latitude of New Brunswick.

In greater part the relations of this " Watchung flexure," as it may 

be conveniently designated, are well defined and indicated by abundant 

observations. The region north of the northern termination of the 

First Watchung Mountain is heavily drift covered, but southward, and 

thence along the flanks of both Watchung ridges to their eiids^ sandstone outcrops are frequent, and the changes in strike easily traced. 

The surface west of the north and south portion of the Second Watchung Mountain is drift or marsh, excepting along the eastern side of 

a portion of the Third Mountain, and the details of the structure are 

somewhat uncertain, but the relations are not likely to be very different from those shown in PI. II. From the narrow belt of northwesterly 

and westerly dips in the strata exposed along the highland border it 

would appear that an anticlinal begins near the southwestern termination of the Second Watchung Mountain outcrops, bears the well defined 

quaquaversal of the New Vernon trap, and thence extends north-north-, 

east across the marsh and drift covered country to Towakhow Mountain. At the southern end of this ridge the shales are pitched beneath 

the surface, apparently by a flat anticlinal, which thence probably con-
U. S. GEOLOGICAL SURVEY BULLETIN NO. 67 PL. II

MAP OF A PO.RTION OF NORTHEASTERN NEW JERSEY, SHOWING THE RELATIONS OF THE

WATCHUNG TRAPS.
WATCHUNG TKAPS. 17

tinues under the marsh eastward, and by again crossing the trap sheet 

causes the cross ridge or east and-west outcrops, as shown in PI. Ill, 

and discussed in detail on a subsequent page. The axis of the Watchung 

synclinal is definitely determinable only where it u spoons" up near the 

southern hooks of the Watchuug Mountains; northward its supposed 

course is covered by marsh and drift, but it appears to have carried the 

trap beneath the surface, between Biker's Hill and Towakhow Mountain, and appears to have aided in the eastern extension of the crossridge of the latter.

In the region southwest of the hooks of the Watchung Mountains the 

northeastern dips prevail for from four to six miles, irregularly and 

gradually giving place to the normal northwestern dips, as shown in PI. 

II. Westward from north of Pluckamin to the New Germantown trap 

the structure is anticlinal, as shown in Fig. 11.

The stratigrapbic position of the Watchung traps in the series is 

somewhat uncertain, but for several miles north and south from Patersou the first Watchung sheet lies on conglomeratic beds apparently 

at the base of the formation and separated from younger members eastward by a great fault having the course shown by K - - - L, PI. II.

The best known exposures of these supposed basal rocks are at Paterson, as noted by Rogers and by Cook. The latter, in his report for 1882, 

page 36, discussed the significance of the occurrence of this shore deposit in the center of the formation as follows:

This conglomerate points to the source of these pebbles as not very far away. Blue 

limestone must have furnished its pebbles. In the absence of any ledges or outcrops 

of the rock anywhere near Patersou, the assumption is that it has been covered by 

the more recent strata, and that the conglomerate deposit was not far from it. Heref 

then, we can not be very far from the base of the formation, one side or the other.

It has been found that these conglomeratic beds are also exposed 

some distance south of Paterson in front of the Great Notch, and in 

considerable force several miles north along Goffle Creek, west of Yan 

Winkle's station, but the country is heavily drift covered and the relations are not readily determinable. In these exposures the conglomerates are composed in greater part of large pebbles of white, gray, aud 

red quartzites, including bowlders up to six inches in diameter of the 

same material, and of limestone.

The conglomerates are separated from the base of the First Watchung 

Mountain by an inconsiderable thickness of sandstones and shales, and 

are succeeded eastward by fine grained materials which dip gently westward towards the coarser beds. At Paterson, a short distance east of 

the conglomeratic outcrops in the gorge of the Passaic, a well was bored 

2,100 feet through fine grained sandstone and shales, and the presence of 

the fault is suggested by the improbability that the conglomeratic beds, 

universally characterizing shore deposition in the formation, would be 

superimposed on or intercalated in such a great mass of fine grained 

materials.

Bull. 67 2
18 TRAPS OF THE' NEW JERSEY REGION. 

The relations in the Paterson region are shown in the following figure

FIG. l. Section through Paterson, New Jersey, looking north. X, Conglomeratic beds. C, Projected 

position of the base of the trap sheet as exposed in the quarries half a mile south of the section 

line.

The extent of this hypothetical fault is not known j its probable course 

northward and for some distance southward is heavily drift covered 

and outcrops are widely separated, but in almost continuous exposures 

near Montclair and Orange there are no traces of either the conglomerate or the fault line.

In the region of the southern hooks the base of the first Watchung 

trap lies on fine grained materials, apparently far above the base of the 

formation, and, as the sheet preserves a uniform horizon throughout, 

its position on the basal members northward would indicate that there 

was a considerable thickness of deposit southward at a time when the 

Paterson region was near the shore line of the formation.

MUTUAL RELATIONS OF THE WATCHUNG TRAPS.

In PI. Ill are illustrated the relations of the trap sheets to each 

other and to the associated sedimentary rocks. It will be shown in succeeding pages that the bases of these trap sheets preserve a uniform 

horizon throughout, and the discrepancies in parallelism of the present 

position of their basal planes, as shown in the figure, are due to dislocations.

It has been suggested that the trap outcrops of the three Watchung 

ridges were due to a single sheet traversed by longitudinal faults bringing up the underlying strata in the intervening valleys, but this would 

be inconsistent with their perfectly concentric course and exact parallelism with the strike. Near each end there are unbroken, unfaulted 

sections from the top of the second Watchung traps to the base of the 

third, and throughout their course the first and second Watchuug sheets 

are separated basally by an amount which varies so slightly as to preclude even the suggestion of dislocation.

The first and second Watchung traps are separated basally by about 

1,200 feet. On section 1 the base of the first Watchung trap down the
U. S. GEOLOGICAL SURVEY BULLETIN NO. 67 PL.

SECTION I.

SECTION

SECTION 3.

SECTION 4.

SECTION 5.

SECTIONS ACROSS THE WATCHUNG TRAPS ALONG THE LINES SHOWN ON PLATE II.
DAKTON.] WATCHUNG TRAPS. ' 19

dip is apparently 1,200 feet below the base of the second Watchuug 

trap; on section 2,1,400 feet; on section 3, 1,200 feet; on section 4, 

1,150 feet ; on section 5,1,250 feet.

With the exception of section 2, these amounts are practically identical, as there is a considerable plus or minus error in the estimates, and 

the greater distance indicated in section 2 is due at least in part to 

known faults. Estimates at a number of points between the sections 

are invariably near 1,200 feet.

The distance between the present positions of the bases of the second 

and third Watchung traps varies considerably ab the outcrops. On section 1 it amounts to 2,400 feet; on section 2, 1,900 feet; on section 3, 

2,400 feet; on section 4, 2,200; on section 5, 2,700 feet. As there is no 

evidence that deformation has taken place between the two extrusions, 

these discrepancies must be due to faults in the Second Watchung Mountain area or in the valley westward, and, as will be discussed further on, 

there is positive evidence of a great fault crossing section 5, and bringing up underlying shales in the center of the trap area. On the line of 

section 2 the sheets are nearer to each other than elsewhere, and as 

there is no evidence of faulting in that vicinity, the distance indicated 

1,900 feet is probably very near the amount of actual difference in horizon. This estimate, then, serves as an approximate basis for the determination of the faults which give rise to the apparently greater 

separation on the other sections; and the thickness of the intervening 

sedimentary members, as shown in Fig. 2.

FIRST AND SECOND WATCHUNG TRAPS. .

General relations. These two sheets are so intimately connected in 

structural relations, nature, and position that they may be conveniently 

considered together. Their outcropping edges constitute the Watchung or Orange Mountains, and as before stated, they represent two great 

sheets separated by about 1,200 feet of strata, which underlie the narrow intervening valley. .

The Watchung Mountains are two long, concentric, and, in places, 

double-crested ridges, curved at their terminations ; the second or inner 

ridge being recurved for several miles along the highland border of the 

formation. The ridges are generally elevated between 300 and 400 feet 

above the surrounding plain country, but notches, depressions, and 

local elevations occasionally break their continuity of crest line. Owing 

to the hardness and structure of the trap, the ridges are defined to the 

eastward and southward by escarpments, which are flanked to a considerable elevation by the sandstones and shales on which the sheets 

lie. The inner sides are gentle slopes in which the trap extends down 

to the overlying strata in the valley or plain below. As the ridges 

closely approximate the trap outcrops in extent, their course and width 

are fully indicated in PI. II, p. 16, and hardly need detailed description. The varying widths are due chiefly to the variations in the thick-
20 TEAPS OF THE NEW JERSEY REGION. [BULL. 67.

ness and structure of the sheets, being narrow where the thickness is 

less or the dips are steeper and wider where the reverse is the case, or 

when the sheet is traversed by faults that depress the east side. Erosion, of course, has been an important factor in determining the width 

of the outcrops, but there is only one instance where a considerable 

variation in width is due to its agencies alone; this is at Paterson} 

where the ridge becomes very narrow, decreases in elevation, and is 

crossed by the Passaic, which falls over its eroded edge into a gorge. 

The wide depression at Little Falls is similar topographically, and is 

also traversed by the Passaic, but the trap sheet is comparatively thin 

in this region, and the diminution in elevation and width is only partly 

due to erosion. The same is the case with the only other wide depression, which is in the thinnest part of the first Watchung sheet at Millburn and at -present the channel of the drainage of a very limited 

area.

In contour the ridges present little variety; usually the inner slopes 

are essentially smooth, but subordinate crests, local lines of escarpments, 

and rounded elevations are found upon them in some regions. The 

outer sides are generally very precipitous; in the Second Watchung 

Mountain steep, talus-covered slopes and occasional escarpments mark 

the edge of the trap sheet. In the First Watchung Mountain long lines 

of mural escarpments generally extend from a very uniform crest line 

to a talus and sandstone slope below and vary from only a few feet to 

a hundred feet in height.

The relations, boundaries, and general structure of the first and.second Watchung sheets are well marked for the greater part of their 

course, but there are some localities in which the outcrops are obscure 

or lacking and the relations uncertain. At the northern termination 

of the First Watchuug Mountain the heavy mantle of drift covers the 

region to such an extent that the boundaries and relations can not be 

definitely determined, but from the occurrence of a number of small 

and isolated trap outcrops in the high country in the interval, and the 

general structure of the region, it is thought that the trap masses of 

the Bamapo Valley are a continuation of the first Watchung sheet. The 

larger of these masses forms a ridge with a summit over 700 feet above 

tide-water level, and is separated from the smaller mass by a narrow 

valley in which some gently west-dipping strata are exposed near the 

Eamapo. At no other point were sedimentary rocks exposed in their 

vicinity, and their structure and exact extent are obscured by the heavy 

flanking of drift. It is possible that the smaller mass is faulted off the 

larger, but it may be entirely separate and due to a local extrusion.

At the southwestern termination of the Second Watchung Mountain 

the case is somewhat similar to the one above noted, as there is some 

uncertainty as to whether the small trap outcrop north of Bernardsville is continuous southward to the second Watchung sheet. The 

latter pitches below the surface when last seen and the intervening
CARTON.] WATCHUNG TRAPS. 21

mile and the vicinity of the outlying mass are obscured by drift and 

detritus, so that no positive evidence could be obtained.

Thickness. Faults. The thickness and faults are two subjects which 

naturally come under one heading, for the estimates of thickness are 

based on evidence involving a consideration of the indications of dislocation.

In the following figure the thicknesses of the trap sheet and intervening sandstones are estimated from the data furnished by the sections in 

PI. Ill, with deductions for faults indicated by the lack of parallelism 

in the present positions of the basal planes of the sheets at their outcrops.

THIRD 

WATCHUNG

SECOND 

WATCHUNG

TP AD

FIRST 

WATCHUNG

 tAI»

==^=^~?

jrSjg:^

I 250

1300

60O

650

I 550

£~-S

g"=g!sR;

300

1250

650

730

450

~ -_-=-----

iSlsifK5SS

lS5l§i

^ 225

1050

I 850

I 600

600

S=^-^z.S

350

1300

1 600

600.

eoo

=T=^ -~^,-.

nsm

I>B= =

sSSSsi

1300

IZOO

ro a

55.0

650

FIG. 2. Sections illustrating the stratigraphy of the Watchung region along the section line shown in

Pis. II and HI.

In discussing the relations of the sheets on a preceding page it was 

shown that the base of the second Watchung trap was stratigraphically 

1,900 feet below the third Watchung trap as indicated in section 2, and 

the first Watchung trap 1,200 feet below the second Watchuug trap, 

which is the mean of allthe measurements when known faults are eliminated. The estimates of thickness of the first Watchung sheet are based 

mainly on cross-section measurements in which the unknown faults can 

not be very considerable in amount. With the case of the estimated 

thickness of the second Watchung sheet, however, the case is different, 

for the trap outcrop is wider and presents evidence of longitudinal 

faults in its topography, and in the varying apparent distances of its 

basal plane from that of the third Watchung trap, from which it was 

originally separated 1,900 feet throughout, if section 2 is not crossed 

by faults. The position and extent of the faults indicated by the discrepancies in the other sections across the Second Watchung Mountain 

are not known with any degree of certainty, and they may in part traverse the sandstone region westward j but in the estimates in Fig. 2 it 

is assumed for the sake of uniformity that they are in the trap area and 

uniformly downthrown on the eastern side.

On the line of section 1 the basal planes of the second and third 

Watchuug traps are now 2,400 feet apart at their outcrops, indicating 

faulting in the intermediate region to the amount of 500 feet, if the
22 TEAPS OF THE NEW JERSEY REGION. [BULL. 67.

original difference in horizon was 1,900 feet. If this faulting is all in 

the trap area the apparent 1,200 feet of trap represents a sheet approximately 700 feet thick as shown in Fig. 2. In this region the ridge presents considerable evidence of faulting, in its double crests and lines of 

low longitudinal escarpments presented eastward and rising from prominent joint cracks. On section 2 the trap is 600 feet, thick in the narrowest portion of its course, and constitutes a low, smoothly rounded 

ridge, apparently not traversed by faults.

Southward from Little Falls almost to its termination the Second 

Watchung Mountain is more or less prominently double crested, and 

the more marked this feature is the greater the apparent difference in 

horizon at the outcrops between the base of its trap sheet and that of 

the third Watchuug trap. In the prominent double-crested portion of 

the ridge in the latitude of Orange, on the line of section 3, the basal 

distance is 2,400 feet, indicating faulting to the amount of 500 feet; and 

if the dislocation is in the trap outcrop with the downthrow on the eastern side, the apparent 1,350 feet of trap represents a sheet 850 feet 

thick. On section 4 the double crest is inconspicuous, the apparent distance between the two trap sheets, 2,250 feet, the faulting 350 feet, and 

the actual thickness of the apparent 1,000 feet of trap, 650 feet. On 

section 5 the double crest is very prominent and clearly due to faulting, 

as shown in PI. Ill, for red shale fragments characterize a strip of 

country between the crests and probably represent underlying strata 

brought up by the fault. Making allowance for this fault, which would 

amount to about 600 feet, the second and third Watchung traps are 

separated basally by 2,100 feet on this section, indicating faulting 

amounting to 200 feet, which reduces the apparent 800 feet of trap to 

600 feet, on the same assumptions as before.

With the first Watchung sheet the case is different, for the estimates 

are less hypothetical, as cross-section exposures are frequent in which 

there is little or no room for faults that could not be detected, and the 

uniform difference in horizon of approximately 1,200 feet between the 

first and second Watchung traps gives a check on the results. In section 1 the dips, elevation of contact and width of outcrop give 650 feet 

as the thickness of the first Watchung trap, with 550 feet of overlying 

strata and no indications of faults. In section 2, at Garret Bock, a 

thickness of 800 feet is indicated, but deducting 100 feet for observed 

faults, the amount is reduced to 700 feet. There are also indications of 

another fault crossing the section in the line of escarpment and double 

crest which extends along the west side of the ridge from West Paterson, and is very prominent southward towards its termination near the 

latitude of Montclair. On section 3, at Orange, the first Watchung 

trap appears to be about 600 feet thick, and the ridge presents no special indications of longitudinal faults. On section 4, near Scotch Plains, 

the thickness is 450 feet, or considerably less than the average, and the 

outcrop is noticeably narrower. In the gaps at Scotch Plains, Plain-
DARTON.] WATCHUNG TRAPS. 23

a-a.

II11

field, and Chimney Kock, fine sections are exposed across the ridge, 

but no evidence of faulting is presented, and the 

thickness is about 500 feet near Plainfield. In 

the Chimney Kock, section 5, the thickness is 

550 feet; thence northwestward the amount increases somewhat and then gradually decreases 

to the termination of the outcrop.

The faults in Garret Rock, alluded to above, 

are finely exposed in the bluffs south of Paterson, 

along the Boonton Branch, Delaware, Lackawanna and Western Kailroad. The two principal ones were described and figured by Da vis in 

his paper on the Triassic Traps and Sandstones 

of the Eastern United States, and are shown in 

the accompanying Fig. 3.

The principal displacement amounts to about 

70 feet, with the downthrow on the eastern side, 

and although the fault plane is not exposed, the 

beds in its immediate vicinity are not noticeably 

disturbed. Northward this fault is in the sandstone region east of the trap, and is not traceable, 

but southward its course appears to be marked 

by a nearly continuous line of depression, which 

crosses the Great Notch as a prominent break in 

the walls, and trending slightly eastward with 

increased depth, passes out of the ridge into the 

sandstone country eastward. The amount of 

dislocation in the notch is less than 150 feet, as 

the underlying sandstones are not brought up 

by it.

Columnar structure. The outcropping edge of 

the first Watchung trap generally presents 

mural escarpments eastward in which columnar 

structure is more or less well defined. One of 

the finest exposures of columns is at the well 

known locality west of Orange, of which illustrations have recently received wide circulation. 

Iddings, in a paper on "The columnar structure 

in the igneous rock on Orange Mountain, New 

Jersey," gives a detailed description of the locality and a plate showing the entire exposure. He 

discusses the genesis of columnar structures in 

general, and shows that the large and small columns graduate into each other, and do not indicate the edges of successive sheets as suggested 

by Cook. He also calls attention to the similarity of the first Watchung trap to that which is poured out as a surface flow in recent times,

£igs|

a-S a

t * ! & e a
24 TRAPS OF THE NEW JERSEY REGION. [BULL.67.

and considers its glassy nature and the disposition ofits columns, " which 

resembles that of many lava sheets in western America," strongly indicative of extrusion.

A few miles north of the Orange columns in some quarries in the 

northern end of Llewellyn Park, heavily columnar trap graduating into 

small, radiating columns is finely exposed, and in Patersou there are 

many outcrops in which this feature is seen, notably at the exposure 

shown in Fig. 8.

Throughout its course the first Watchung trap exhibits this complex 

structure more or less distinctly, and on the back of the ridge and in 

the notch sections the small columns are frequently seen to graduate 

into heavily bedded rock, forming a part of the original upper surface 

of the sheet. The bedding is parallel to that of the sedimentary rocks 

inclosing the sheet, and is often quite distinct, especially on West street, 

Paterson, and back of Orange and Montclair.

The Second Watchung Mountain seldom presents fine instances of 

columnar structure, but small columns on bedded trap are finely exposed at and near the Little Falls. Generally the Second Watchung 

Mountain rock, like much of that of the first Watchung mass, breaks 

down in wedge shaped prisms and small, irregular columns, and its edge 

is not often marked by conspicuous escarpment.

Succession of sheets. When the great thickness of the Watchung 

trap masses is considered it seems exceedingly improbable that they 

could represent single outflows. Throughout their extent the trap of 

both ridges is remarkably uniform in composition and structure, so that 

it is difficult to obtain evidence of successive flows.

The marked difference in prismatic structure, as described above and 

shown in Fig. 8, is sometimes very suggestive of successive sheets, 

but detailed examination has always shown a graduation from the one 

kind to the other, and the most striking instances of this nature at 

Orange and Paterson exhibit this graduation very plainly at every 

point. Throughout the study of the first Watchung sheet, evidence of 

successive flows was earnestly sought, but without success. In the 

Second Watchung Mountain, however, indications were found of contacts of the base of one flow with the irregular, vesicular surface of a 

preceding one, and three exposures were discovered; one near each 

end of the outcrop, the other at Little Falls. The most marked instance 

is in the railroad cut, just east of Bernardsville station, where the relations shown in the following figure exist:

FIG. 4. Section at Bernardsville station, showing superposition of trap at the termination of the 

Second Watchnng Mountain. Looking southwest. Scale, 60 feet to the inch.

The lower trap is similar to the upper mineralogically, but it is somewhat darker and more crystalline, less decomposed, and less conchoidal
DABTON.] WATCHUNG TRAPS 25

in fracture. Near the contact it is reddish or reddish brown in color 

at some points, and is generally vesicular for several inches. The upper 

. trap is a dense bluish gray rock, slightly vesicular at some points and 

obscurely bedded near the contact. The exact line of contact is not 

always well defined, and at some places the traps are separated by an 

inconsiderable thickness of breccia of trap-fragments imbedded in 

slightly altered argillaceous material. Excepting in this cut, and fora 

few yards in its vicinity, no other outcrops of the lower trap were recognized. It is possible that this locality exposes the vent through 

which the newer trap was ejected, but this could not be definitely 

determined.

At the northern end of the Second Watclmng Mountain there is moderately good evidence of perhaps three flows. The first exposures are 

in the roadside along the upper end of Pompton Lake, where, at several 

hundred feet above the base of the sheet, there is a cross-section exposure in which a layer of vesicular trap,is seen graduating downward 

into firm rock and is abruptly overlain by similar material apparently 

at the base of a succeeding sheet. Some distance farther westward 

vesicular rock is again exposed about 150 feet above the first, and it is 

similarly succeeded by firm rock, which thence extends to the overlying sandstone a short distance westward. The following section is in 

part ideal, and it is not by any means certain that the outlined relations 

actually exist in their entirety.

SECOND WATCHUNG MOUNTAIN. WATCHUNG

TRAP.

FIG. 5. Section along road on southeastern shore of Pompton Lake, showing position of vesicular 

beds in the second Watchung trap. Looking southwest.

At Little Falls a succession of flows is indicated by an irregular, horizontal streak of vesicular rock, also noted by Davis, which is interbedded in massive and columnar trap just above the canal crossing and 

about 150 feet above the base of the sheet. At some points this streak 

appears to include some fragmental materials, but the evidences in this 

regard are not positive. The exposure is a short one and somewhat 

obscure, and no contact line could be detected, but the occurrence is 

suggestive of the vesicular surface of one sheet overlain by the base of 

a succeeding one.

The surface of the trap sheets and their contact relations with the inclosing strata. In their vesicular and altered surfaces and relations to 

the inclosing strata the Watchung traps present conclusive evidence of 

their extrusion, not locally as suggested by Cook, but throughout their 

entire extent. Although the western slopes of the ridges are in most
26 TRAPS OF THE NEW JERSEY REGION. | BULL. 67.

places deeply eroded, decomposed, or drift-covered, there are many localities in which vesicular or slag-like rock still remains, and near Feltville 

the irregular, vesicular surface of the first Watchung trap is exposed,. 

overlain by unaltered red shale, separated from the volcanic rock at 

some points by a trap breccia. In their relations to the underlying 

strata, the Watchung traps present none of the characteristic features 

of the palisade sheet, but the more or less altered trap lies with perfect 

conformity upon practically unaltered, undisturbed shales, and at the 

same horizon throughout.

The Feltville locality is in a small ravine, across the creek, a short 

distance northeastof the village and exposes a cross-section for 200 yards 

along the original trap" surface, and through overlying strata on the 

western slope of the First Watchung Mountain. Owing to the peculiar 

manner in which some of the trap in this exposure is altered, it was 

thought for many years to be highly indurated shale, indicative of the 

intrusive nature of the first Watchung sheet, and in the introduction 

an account is given of the controversy which this has occasioned. In 

Rogers's description, report for 1840, page 134, it is stated that the shales 

and intercalated limestone bed were greatly disturbed and altered by 

the trap, and Russell in his paper on "The Intrusive Nature of the Triassic Trap Sheets of New Jersey," describes the locality in considerable 

detail, calling attention to the vesicularity of some of the trap and its 

rounded slaggy surface, but mistaking its highly altered variety for 

indurated shale. In several reports Cook alludes to the locality as one 

exhibiting the contact of the trap and highly altered shales, and appears to consider the breccia a metamorphic product, but he does not 

give a detailed description of the exposure. In his paper on the 

"Triassic Traps and Sandstones of the Eastern United States," Davis 

gives an account of a hurried visit to the locality, in which the unaltered 

shales are stated to extend down to the vesicular trap surface excepting 

where a trap breccia intervenes. He considers the occurrence of this 

breccia strong evidence that the Watchuug traps are extrusive, " as it 

is difficult to understand how it would have been formed except on the 

surface of a preexistent sheet of lava."

Before making detailed studies of the relations of the Watchung 

traps, I held the same opinion in regard to the Feltville locality as Russell and Cook, but after the appearance of Davis's paper a microscopic 

examination was made by Mr. J. S. Diller of the so-called altered shales, 

and they were found to be highly altered diabase, greatly decomposed, 

but presenting unquestionable evidence of its igneous nature. In this 

way it was easy to understand Russell's very natural error, and the significance of Davis's conclusions were for the first time appreciated.

In the following figure (Fig. 6) the more general relations of the Feltville section are shown and the position of the locality is indicated by 

F on PI. II, p. 16.
DARTON.] WATCHUNG TKA|»S. *

. 1891 )

Excepting in the vicinity of X the uneroded^i-aiurfaceCQu.eiS'ts ( 

smooth, low bosses, two or three feet in diameter? 

or two of enamel-like, ropy surfaced, light colored, fine 

grained diabase. This sheathing is generally filled with 

shot- like masses of calcite and it graduates downward 

sometimes into firm or columnar trap, but generally into 

vesicular rock, often filled with elongated, radial vesicles. 

In places these bosses are separated from each other by 

reticulating bands of chloritic matter or decomposed 

trap an inch or two in width, and extending downward 

for several inches. Along the southern side of the gorge, 

at X, the trap surface loses its bossy contour for some 

distance and becomes a mass of irregular, partly separated, ragged fragments similar to the Aa of the Sandwich Island lavas, as described by Button and others. 

It is at intervals in this portion of the section that the 

breccia occurs, filling the insterstices and capping the 

rough surface, as shown in a general way in Fig. 6, and 

no traces of the rock were found at other points. The 

breccia consists of masses of more or less vesicular trap 

of all sizes, from that of a bushel basket down, in. a matrix of soft, bright red shale deposit and small fragments 

of decomposed trap. The greatest development of the 

breccia is at the so-called "copper mine," where the 

thickness is eight feet, and it is exposed, graduating 

upward into the red shales which form the upper twothirds of the walls of the lower half of the ravine and 

which are elsewhere frequently exposed down to the trap 

surface without intervening breccia. Generally these 

shales are bright red in color, but in the vicinity of Y 

they are intermixed with trap sand and are so darkened 

by it that their contact with the underlying brownish 

red, highly altered trap is hardly recognizable to a casual 

observer.

At the foot of the ravine, and thence southward for 

many miles down the valley between the First and Second 

Watchung Mountains the vesicular trap surface and unaltered shales are frequently exposed very near together, 

but not in contact. Northwest of Plainfield, near the 

Stony Brook gorge, the trap surface outcrops in the 

road-side, and the alteration has at some points progressed until the 

deeply vesicular diabase is almost entirely converted into a bright 

emerald green mixture of chlorite and serpentine. Two and one-half 

miles farther southwest, at an old copper mine, near the hamlet of 

Warrenville, a shaft sunk through the overlying shales penetrated the 

surface of the first Watchung trap for some distance, but the openings

\i||iW

cS 1-5

0 S

-a t- II
28 ' TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

are now filled with water, and nothing could be learned of the relations 

excepting from the heaps of excavated rocks in the vicinity. The 

fragments of trap found in these heaps are of an olive green rock with 

abundant vesicles filled with shot-like masses of calcite, and apparently 

having an enamel-like surface composed of darker, fine grained, more 

vesicular material. No traces of intervening breccia were found, and 

the overlying shales are carbonaceous and sparingly impregnated with 

malachite, azurite, calcite, and coal, but otherwise unaltered.

Four miles west of Bound Brook, near Martinsville, there is an old 

opening for copper at which the surface of the first Watchung sheet is 

exposed, and four miles farther northwest, near Pluckamin, there is 

another similar locality. In both of these instances the trap was very 

vesicular and has undergone considerable alteration to chloritic and serpentinous material.

Northward from Feltville, in the glacial driftregion, the trap is either 

glaciated down to the bottom of the valley, or heavily flanked with 

debris, and although the unaltered, undisturbed, overlying strata are 

exposed very near the contact at the latitude of Orange, and four miles 

north of Paterson, the relations at the immediate juncture could not 

be determined. There is, however, a fine exposure of the vesicular surface of the first Watchung trap in the excavations at the lower end of 

the Orange waterworks, where the vesicularity extends at least ten feet 

below the somewhat eroded surface, and the zeolite-filled vesicles often 

attain an inch or two in diameter.

West and southwest of Paterson the surface of the first Watchung 

trap has a globulitic, rusty fracture, and is frequently vesicular. Along 

the Passaic, near the Delaware, Lackawanna and Western Eailroad 

bridge, there is an exposure described by Davis, in which the trap surface is bossy and slag-like, similar to that which predominates in the 

Feltville ravine, and the rock in the vicinity is vesicular at some outcrops.

Four miles north of the western part of Paterson there is an exposure 

at the base of High Mountain, in which the shales outcrop within fifteen 

feet of the first Watchung trap, and about four feet above it vertically. 

There is no perceptible alteration or disturbance of any kind in the soft 

argillaceous shales, and the somewhat eroded trap surface presents no 

traces of vesicularity.

The surface and inner side of the Second Watchung Mountain are 

more obscured by drift and other detritus than is the case with the First 

\Watchung Mountain, and there are no outcrops of overlying strata near 

the trap, and fewer localities of vesicularity. In its south westernmost 

outcrops and the outlier near Beruardsville vesicular trap is exposed in 

places, and at the latitude of Montclair the deeply glaciated rock on 

the western slope of the mountain contains some large quartzitic amygdules, but it is not until Paterson is reached that a vesicular surface is 

conspicuously exposed. Thence northward at many poiuts the decom-
WATCHUNG TRAPS. 29

posed surface rock is deeply vesicular over wide areas, a feature which 

is especially noticeable near the northern termination of the mountain 

towards Pompton Lake.

The base of the first Watchung trap is exposed at a number of localities, notably at Paterson and near Somerville, but also in the copper 

mines in the gorges northwest of Plainfield and Bound Brook. In all 

the instances observed the trap is considerably altered, more subject to 

decomposition than that of the main mass of the sheet, and lies upon 

unaltered, or very slightly altered, undisturbed shales along a straight 

or slightly sinuous line. In the copper mines, three miles north of Somerville, the slightly undulating contact plane is exposed over a considerable area by the mining operations, and the relations are finely exhibited. The trap is considerably altered near the contact, and is sparingly 

vesicular at some points and slag-like at others.

The sandstones are slightly darkened near the trap and impregnated 

with copper compounds, the results of chemical deposition not necessarily connected with heat. The upper layers are generally slightly 

flexed to conform to the undulating surface of the trap, and at one 

point in the mine there is an intervening breccia from half an inch to 

an inch in thickness, composed of trap fragments imbedded in a matrix 

of essentially unaltered shaly material. The relations of this singular 

breccia are shown in the following figure (Fig. 7), and it is thought that 

its trap fragments were derived by some means from the edge of the 

advancing trap sheet and then overflowed by it:

.Base of trap sheet.

FIG. 7. Section of breccia immediately below base of first Watchung trap in American Copper Mine 

near Somerville, New Jersey, a, trap fragments; 6, sedimentary matter. Jnat. size.

In Chimney Rock gorge, northwest of Bound Brook, and in Stony 

Brook gorge, northwest of Plainfield, openings for copper ore exposed
30 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

the contacts for some distance, but the workings were not accessible 

at the time of my visit. Other exposures in their vicinity exhibit the 

contact along a gently undulating line similar to that in the American 

Copper Mine above alluded to. Northward from south of Orange to 

Paterson the entirely unaltered shales and sandstones are exposed at 

many points along the side of the mountain very near the trap, and 

perfect conformity exists.

At Paterson there are fine exposures in Garret Rock, in the several 

sandstone quarries, in the railroad cut behind Barber's mills, and at 

places in the gorge of the Passaic in which the trap extends down to a 

sharp contact line without showing conspicuous change in color or texture except occasional vesicles and slightly finer grain or a smaller 

conchoidal fracture. On the south side of the gorge of the Passaic 

just below the falls, there is the exposure shown in the following figure 

(Fig. 8), in which the contact is very finely exhibited for over a hundred 

yards:

J

PIG. 8 Cross-section exposure of edge of first Wntchung trap lying on sandstones on the south side 

of Passaic River, just below the Great Falls, Paterson, looking south. From a photograph.

In this exposure the line of contact is almost perfectly straight throughout, the trap lying upon moderately argillaceous sandstones slightly 

flexed and darkened at some points, and in places containing cavities 

apparently due to the weathering out of infiltered minerals. The trap
BARTON. J WATCHUNG TRAPS. 31

is generally slightly vesicular near the contact and in irregular bands 

for some distance above, and to the right of Fig. 8 it is altered to a light 

flesh colored, vesicular rock which occurs at intervals for several yards. 

Only two exposures of the base of the second Watchung trap are 

known, and both afford very satisfactory exhibitions of the contact relations. Some features of the exposures along the Passaic and in the 

quarries opposite Little Falls were described by Kogers and by Davis, 

and the other localities are in the quarries near Haledon, two miles 

north of the western part of Paterson. The finest exposure showing 

the relations of the trap to the sandstones at Little Falls is the one 

shown in the following figure (Fig. 9) at the quarry of the Little Falls 

Brownstoue Company:

Fig. 9. Contact of second Watchung trap with underlying sandstones in quarry on north side of 

the Passaic River below Little Falls. From a photograph.

In the vicinity of this exposure neither the trap nor the sandstones 

are noticeably altered in texture or in color, and the contact is along a 

perfectly horizontal line, but westward near the falls and farther eastward down the Passaic, the base of the sheet appears to have overflowed 

some beds of scoria and tuff. In the outcrops just below the falls on 

the north side of the Passaic the firm columnar trap at first is intercalated with and then it graduates downward into vesicular and apparently scoriaceous rock, but the exposures are obscure and the exact 

relations uncertain. A half mile below the falls on the same side of
32 TRAPS OF THE NEW JEESEY REGION. [BULL.67.

the river there is an exposure of the edge of the sheet in which the relations shown in the following figure (.Fig. 10) appear to exist.

3?IG. 10. Supposed tuff and scoria beds overlain and penetrated by the columnar trap at the edge of 

the second "Watchung sheet on the north side of the Passaic River, half a mile below Little Falls, 

looking northwest. From, a photograph.

The fraginental beds consist of a loose, heterogeneous mixture of vesicular fragments of all sizes and fine grained decomposed tufaceous and 

ashy materials, all so much decomposed as to render the specific identification difficult. The columnar trap appears to graduate into this bed 

at the contact, but it appears probable that here we have an anterior 

fragmentary deposit overflowed and penetrated by lava flows in the 

manner shown in the figure, in which the features are somewhat accentuated.

Northward from this locality for many miles the drift and talus hide 

the base of the sheet, and the extent of this supposed fragmental deposit is unknown. The Haledon exposures are in two adjoining sandstone quarries, a mile and a half north of Haledon. In the northernmost of these quarries the columnar trap is vesicular at some points 

near the contact and includes masses and streaks of chloritic matter in 

which rounded and angular masses of vesicular trap are imbedded. In 

the other quarry a couple of hundred yards away the firm, hard columnar trap of the ridge comes down to the unaltered sandstones at some 

points, but it generally lies on from 10 to 20 feet of a heterogeneous deposit of fragmental material similar in nature and relations to that 

below the Little Falls, cemented into a breccia by zeolitic, quartzitic, 

and calcic impregnations.

THIRD WATCHUNG TRAP.

General relations. The outcropping edge of this sheet constitutes a 

line of single crested ridges known as Packanack Mountain, Towakbow 

Mountain, Biker's Hill, and Long Hill, which are shown on PI. II as 

trap-covered areas a short distance west of the inner slopes of the Second Watchung Mountain. These ridges are narrow, seldom exceeding 

half a mile in width, and, although similar to them topographically, 

are much less prominent and rugged than the Watchung Mountains. 

Through much of their course they present a steep side eastward, but 

escarpments are infrequent, low, and irregular, and the line of contact 

with the underlying sandstone is generally not far below the crest line. 

The inner slopes are trappean and gentle. The ridges ordinarily attain ail elevation of about 200 feet above the surrounding plains, but
DAUTON.J THIRD WATCHUNG TRAP. 33

occasionally somewhat more. Owing to the comparatively inconsiderable thickness of the sheet, slight changes in its thickness, extent, or 

structure cause breaks in the continuity of its outcrops or considerable deflections in its course, such as are not found in the larger 

Watchung masses.

The most notable of these deflections is the bowing in the line of 

outcrop in Towakhow Mountain. The curved course of this ridge is 

apparently due to a very low anticlinal, or crumple, trending and gently 

declining northwestward and crossing the sheet in the angle formed by 

the change in trend. There is a gradual change of dip approaching 

this corner from the south, and although in the eastaud-west or 

cross-ridge the trap extends down to country level, and the regions 

north and south are drift and marsh covered, the evidence seems ample 

that its course is due to flexure. In the north-and-south ridge the 

sandstone extends up nearly to the crest, dipping a,bout ten degrees to 

the northwestward conformably under the trap.

The cross ridge terminates in a few miles at a low, wide, marsh and 

drift-filled gap, through which the Pequannock River crosses the sheet. 

East of this gap the trap outcrops constitute a curved ridge, which 

thence extends parallel to the strike and gradually sinks below the 

drift plain near Pompton. Towards the southern termination of the 

Towakhow Mountain the sandstone outcrops finally cease and the 

trap sheet pitches beneath the surface in the gap towards Riker's Hill, 

apparently passing over the southward extension of the anticlinal to 

which the cross-ridge is due. The trap in Biker's Hill rises gradually 

from the plain country, either by slight flexure or byincreasein thickness 

of the sheet, and is a thin capping of trap on gently west dipping shales, 

which extend nearly to its crest. Long Hill is similarly constituted, 

and at its southern termination the trap is spread out in the spoon of 

the Watchung synclinal to cover an ill defined but considerably greater 

area than shown on the map of the New Jersey Geological Survey.

North of the corner of the Towakhow Mountain there are two poorly 

exposed outlying outcrops of trap near the highland border, and it seems 

probable that they are part of the third Watchuug trap separated by 

erosion or continuous under the surface in the interval.

Thickness. The thickness of the third Watchung trap is somewhat 

variable, but as its outcrops do not appear to be traversed by faults 

the amount may be satisfactorily estimated at a number of localities. 

The sheet gradually rises out of the glacial lake beds near Pompton, 

and in the deep gorge of the Eamapo River, a half mile south, has a 

thickness of at least 215 feet. Five miles farther south the amount is 

near 400 feet, and in Towakhow Mountain near 450 feet in the northand-south ridge, and at least as much in the cross ridge. In Hiker's 

Hill the thickness is between 200 and 250 feet, but in Long Hill the 

average is near 250 feet, and at some points it may be 275 feet. (See 

also Fig. 2.)

Bull. 67 3
34 TRAPS OF THE NEW JERSEY REGION. |J3ULL.67

Bock structure. The third Watchung trap is a fine grained rock, 

similar in every respect to that of the other Watchung ridges. Its 

structure is seldom columnar, and ordinarily it breaks down into wedge 

shaped masses of small size. Although the upper surface of the sheet 

is deeply decomposed and eroded southward, and bears indications of 

severe glaciation northward, some vesicular rock still remains. This is 

an especially noticeable feature near the latitude of Paterson, but is 

also seen north of Millington, and in the southern hook.

Relations to the associated sedimentary rocks. 7Although the third 

Watchung trap is only seen in contact with underlying strata near its 

northern and southern terminations, and contacts with overly ing strata 

are not exposed, there is ample evidence to prove that it is an extrusive 

sheet. The underlying contacts present precisely the same features as 

those of the other Watchung traps, and at other localities the strata frequently seen very near the trap are entirely unaltered and are conformably overlain by the sheet, the course of which is primarily determined 

by their flexures. Beginning at the south the shales are often exposed 

near the trap, and in the gorge at Millington the contact is finely exhibited for several yards. In this exposure the slightly vesicular, decomposed base of the sheet is a sinuous line, perfectly conformable to the 

bedding of the shales. The latter are entirely unaltered, excepting 

slight local increases in hardness, and although there is no disturbance 

in the bedding, some of the layers of shale are slightly bent, distorted, 

and indistinct for a short distance from the contact. Northward from 

Millington the sandstones and shales extend along the eastern face 

of Long Hill and Biker's Hill and the southern part of Towakhow 

Mountain, sometimes very near the trap, but not exposed in contact. 

In the gorge of the Eamapo, near Pompton, about a mile south of the 

northern end of the ridge, there is a fine exposure in which the trap 

is seen lying on calcareous conglomerate dipping conformably to 

the southwestward. The exact line of contact is not exnosed, but a 

few inches from it the trap is firm and dense, and the calcareous rock 

entirely unaltered.

No exposures of contact with overlying strata are known, and in 

most cases the nearest outcrops on the inner slopes are at a considerable 

distance from the trap. A mile north of Millington, on the road to 

Basking Eidge, there are some very argillaceous shales, which, at one 

point outcrop within five or six feet of the surface of the sheet, and do 

not present the slightest signs of alteration.. A mile southeast of Basking Ridge there is another exposure of unaltered shales near the trap, 

but the exact distance from contact can not be ascertained.

NEW VERNON TRAP.

Three miles northwest of Long Hill, and separated from it by the 

Great Marsh, is a semicircular trap outcrop which extends to within a 

few rods of the border of the formation. It is the edge of a lava sheet
U. S. GEOLOGICAL SURVEY BULLETIN NO. 07 PL. IV

MAP OF THE REGION ADJACENT TO THE NEW VERNON TRAP, LONG HILL, AND THE INNER SIDE 

OF THE TERMINAL HOOK OF THE SECOND WATCHUNG MOUNTAIN.
DABTON.J NEW VERNON TRAP. 35

outcropping up the sides of an irregular quaquaversal, and may be either 

the attenuated western extension of the third 

or second Watchuug sheets brought to the surface by flexure, or a local extrusion. In PI. II, 

the general relations of this outcrop to the 

others is indicated, and in PI. IV its structural 

and areal relations are shown.

With the exception of a couple of narrow 

drainage gaps the main outcrop line of the sheet 

is marke'd by a ridge about 200 feet in height 

and with a width somewhat greater than that 

of the trap outcrop.

In contour the ridge is not as steep and rugged as the Watchung Mountains and its steeper 

inner slope is not marked by escarpments. 

The ridge is single-crested northward, but towards its southern termination it is divided 

into knobs and subordinate ridges. The southernmost outcrop is in a small, isolated knoll, 

and is apparently separated on the surface, 

although possibly continuous with the main 

mass under ground. The New Vernon trap is 

a fine grained rock, very much decomposed 

superficially, but notably vesicular and slaglike in places on its surface, and very similar 

on the whole to the rocks of the Watchung 

ridges. The thickness of the sheet is between 

150 and 200 feet, and becomes very slight in the 

north westernmost outcrop. There is every 

evidence that the sheet is perfectly conformable to the sedimentary rocks throughout. The 

underlying sandstones and shales flank the 

inner side of the ridge, and, as shown in PI. IV, 

their strike is closely parallel to its trend. 

Outcrops near the trap are infrequent, but in 

the one or two instances observed there were 

no traces of alteration. The only exposures of 

overlying beds are some distance southward, 

along and near the Passaic Eiver, where the 

unaltered shales dip as shown in PI. IV. 

Southwest of these exposures, to the second 

and third Watchung traps, the strikes vary 

from west to northwest, so that the relative 

stratigraphic position of the New Vernon trap 

could not be exactly determined; but it is 

probably connected with either the one or the other eastward under the 

Great Swamp, or southward below the surface.

'NOJ.ONIWVI:

SdVWJ.

NMOJ.IMVWM39 

/V\3N
36 TRAPS OF THE NEW JERSEY REGION [BULL. 67.

NEW GERMANTOWN TRAP.

Lying near the border of the formation west of New Gerinantown, 

seven miles west of the hooks of the Watchung Mountains, there are 

two small trap outcrops which are similar to the Watchung traps in 

their relations, and possibly an extension of these flows; for, as shown 

in Fig. 11, the intervening country is anticlinal in structure, and, if no 

faults traverse it, the traps on either side are at approximately the same 

horizon.

The New Germantown trap outcrops constitute a semicircular ridge 

inclosing a prominent central knoll, as shown in Fig. 12.

TRAP SHALES & GNEISS. 

CONGLOMERATES,

FIG. 12. Map of the New Germantown trap region. 

L E, line of section shown in Fig. 11.

The outer ridge consists of a trap sheet lying conformably between 

unaltered shales with its curved course determined by a shallow trough 

or partial ceutroclinal having the relations shown in the figure. The 

trap presents its steeper face to the east and south and its outcrops terminate by the thinning out of the edges of the sheet. At greatest its 

thickness is about 250 feet. The sheet is exposed in cross-section along 

North Rockaway Creek, but at no point is it seen in actual contact with 

theanclosing strata, although there are outcrops at some points very 

near the trap in which the shales are entirely unaltered and undisturbed in bedding.

0 The central knoll is abrupt and high, but its surface and slopes are 

so covered with trap fragments that its structural relations are not entirely determinable. The dips in the adjoining strata indicate the struct-
BARTON.J PALISADE TRAP. % 37

lire shown in Fig. 11, and from the absence of alteration in the beds it 

seems improbable that the trap mass is a dike or intrusive sheet.

The trap of both the curved ridge and the knoll is fine grained rock, 

similar to most of that of the Watchung Mountains, and although vesicularity was not observed in the deeply decomposed and eroded surface 

of the sheet, and contacts with inclosing strata were not seen, there 

seems little doubt that the rock was extruded contemporaneously with 

the deposition of the sedimentary members of the formation.

PALISADE TRAP.

General relations. This great mass of intruded diabase forms one of 

the most conspicuous and best known topographic features in New 

Jersey. Its comparatively narrow outcrop extends as a high ridge 

with palisadal front for thirty miles along the western side of the Hudson River from New York Bay to Haverstraw, and thence around a 

huge hooked course to the Highlands.

The palisade trap above the present surface is in greater part a thick 

sheet, which was intruded up the west-dipping strata from a dike which 

follows at or near the western flank of the outcrop. This dike-andsheet structure is best exposed in the railroad cuts and tunnels across 

the ridge at Weehawkeu and near Haverstraw, and is shown in the 

sections in Figs. 13 and 14, viz:

.i^^TlS^^^^^^^M^^^^^^^^^^^^S^^

'^S'Aft D8T6NES^-^feSj4^^^r'r""

FIG. 13. Section showing the structure of the palisado trap along the line of the West Shore Railroad in the tunnel and cuts west of Weehawken, New Jersey, looking north.

IOOO FT 

FIG. 14. Section similar to preceding, hut three miles south of Haverstraw, New Tork, looking west.

For many miles along the Hudson Eiver the base of the sheet is frequently exposed, and while it preserves a practically uniform horizon 

near the base of the formation, many local irregularities are seen in 

which the trap crosses underlying strata laterally up or down, in some 

instances for over a hundred feet. In the hook extending from Haverstraw westward the sheet ascends in the formation by successive steps, 

and at its north westernmost outcrop at the Highland border presents 

some evidence of having been extruded.
38 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

Beginning at the south the palisade trap is first found in wells near 

the Fresh Kills, on Staten Island, but it soon comes to the surface and 

constitutes a hill extending to the Kill von Kull. On Bergen Point 

the outcrop is inconspicuous for some miles, but finally develops into a 

ridge which gradually increases in elevation northward and is characterized by au escarpment on its eastern side. This ridge reaches the 

Hudson River at Weehawken and thence continues northward with 

palisadal front to the State line, its elevation increasing in the interval 

from 225 to 550 feet.

In Eockland County, New York, the topography of the ridge becomes somewhat irregular, a deep.notch crossing it at Piermont, north 

of which it rapidly increases in elevation and width. Near Nyack the 

elevation decreases, and towards Rockland Lake the ridge becomes very 

narrow for a short distance. Thence northward the Hook Mountain is 

a high, rough, single crested ridge, bearing the abrupt knobs or increased elevation known as the High Torne, 1,008 feet above tide and 

the Low Torne, 900 feet above tide. Towards its termination the ridge 

gradually decreases in altitude, and is crossed by a wide depression 

extending down to country level near the line of the New Jersey and 

New York Rairoad.

In contour the Palisade Mountain and its prolongations is generally 

a single crested or slightly corrugated ridge, with gentle western slopes, 

often flanked by overlying strata, and with an escarpment eastward in 

which a greater or less thickness of trap caps the underlying strata.

The columnar wall, which is so characteristic of the ridge, begins in 

Jersey City, and for some miles the columns are moderately well denned, 

but along the Hudson River from Fort Lee to the State line the great 

even crested wall at the edge of the sheet is a continuous line of huge 

columns extending down for three to four hundred feet to the steep 

talus along the river. The following figure (Fig. 15) gives a general

FlO. 15. The Palisades of the Hudson opposite Hastings, New York. From a photograph.
BARTON.] PALISADE TKAP. 39

idea of the evenness of the crest line and escarpment, but very inadequately represents the grandeur and prominence of the exposure.

The palisade trap is remarkably uniform in cdnstitution, and although 

its texture varies somewhat, it is a normal, almost glassless diabase 

throughout. Near its contact with the inclosing sediments it is fine 

grained, sometimes for a considerable distance, and different portions 

of the sheet vary somewhat in texture, but the predominating rock is 

a moderately coarse grained, dense gray rock in which the constituent 

minerals may be discerned. Immediately at its northwestern termination, the surface of the sheet is vesicular for a few rods of its course, 

and the rock is very similar to that of the Watchuug flows. Otherwise 

it is unlike the fine grained, glassy, extrusive rocks, and at no other 

point presents the slightest vesicularity.

So far as known the palisade trap sheet is the result of a single intrusion, continuous from beginning to end, but it may possibly be connected under ground with the smaller posterior sheet at Gran ton, and it 

is undoubtedly the source of the several small sheets which are intruded 

in the immediately underlying strata at Weehawken, King's Point, and 

near Haverstraw.

There is some probability that the palisade trap reappears southward 

in the Lawrence Brook trap, which is along the extension of its projected 

line of outcrop. The interval between the Staten Island outcrops and 

those at Lawrence Brook is mostly covered by cretaceous clays under 

which the Newark is known to extend for some distance, and it is possible that the trap continues southward and is similarly overlapped. 

The small trap masses near New Brunswick occur in this region, and in 

Cook's report for 1882, page 59, reference is made to a belt of indurated 

shales found in excavations in the Earitan River, a little below Martin's 

Dock, which may indicate the presence of the extension of the palisade 

trap. Union Hill, just northeast of Sufferns, may also be an extension 

from the edge of the palisade trap, but the intervening region is driftcovered, and the relations are uncertain.

Structural relations in the palisade region. The palisade trap is not 

flexed to any great extent, and although there are in its area a number 

of topographic and structural features suggestive of dislocation, only 

two well defined faults were found.

In its course along the Hudson River nearly to Haverstraw the 

sheet lies on strata dipping gently westwardly and striking parallel to 

the general trend of the ridge. Local variations in direction and amount 

of dip are not unusual, but their influence is in most cases confined to 

increasing or decreasing the elevation of the contact line in the face of 

the cliff, although in some cases causing slight deflections in the trend 

of crest line. The increased width of the ridge near Nyack is in part 

due to the thickening of the trap, but the dips in that region are very 

low and aid in widening the outcrop. North of the State line the strata 

are inclined due west in most instances, and the average trend of the
40 TRAPS OF THE IS'EW JERSEY REGION. IBULL. 67.

ridge is north for over 10 miles. Near Haverstraw the great hooked outcrop begins, and its structural relations are somewhat complicated. The

FIG. 16. Map of Rockland County, New York.

similar great hooks of the Watchung Mountains, it will be remembered r 

are due entirely to flexures, but in this instance the structure of the 

associated strata facilitates the curved outcrop but is not its principal 

cause. Primarily the hooked outcrop is determined in greater part by a 

gradual deflection in the course of the dike from north and south, finally 

to due east and west, but at the same time the base of the sheet ascends 

laterally westward several hundred feet. If this was not the case the 

sheet would be carried below the present surface by the inclination of 

the gently west dipping monocline into which it was intruded. These 

changes in elevation in the sheet may possibly be due to or aided in 

greater or less part by two faults, the presence of which is suggested by
DAKTON.] PALISADE TRAP. 41

the topography of the Long Clove a,nd the Short Clove. These two 

deep gaps cross the ridge near Haverstraw, 

in the very region where the principal changes 

in position are effected.

The dike structure is plainly exposed in the 

inner side of the hook from L to K, being 

finely exhibited in the railroad cut at K, as 

shown in Fig. 26. Elsewhere its presence is 

indicated by the steeper inclination of the 

trap slopes than that of the adjacent strata 

frequently exposed in its vicinity, although 

in some part, at least, the appearance may 

be due to faulting. On the outer side of the 

ridge along the Hudson Eiver, southeast of 

Haverstraw, the dips are very gently to the 

westward in most cases, but southwestern 

dips occur occasionally. South of Haverstraw 

the west-southwest dips are general, and it is 

here that the face of the sheet is either intruded upward across the edges of the strata 

in several step-like irregularities or is faulted 

so as to preserve a considerable elevation in 

the bluff notwithstanding the tendency of the 

dip to carry it downward. West of Haverstraw there are no outcrops near the trap until 

on the road-side near Theils, where, as shown 

in 'the map, some pebbly conglomerates dip 

gently southward. In the region northwest 

of Haverstraw the shales dip at very low 

angles to the west and north, and near the 

Highland border the calcareous conglomerates are involved in a shallow synclinal which 

extends southward and crosses the palisade 

trap west of L in a wide depression through 

which the New Jersey and NewYork Eailroad 

passes. The recurved course of the termination of the trap outcrop is due to this syncline, 

which is well defined near Ladentown, where 

its relations are as shown in Fig. 17.

The horizon held by the sheet at its southwestern termination is not far from the top 

of the formation, which in this region has no 

great thickness.

Faults. Wherever the palisade trap is exposed in cross-section it appears to be traversed by small faults which offset its horizontal joint planes, and there

>
42 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

m

are several longitudiual depressions and subordinate escarpments on 

the Palisade Mountain which are possibly due to dislocation. In studying the palisade trap it was soon discovered that a longitudiual fault 

extended along Bergen Hill from Bergen Point 

through Jersey City heights to the latitude of Hoboken, and another was found in the ravine behind 

King's Point north of Hoboken extending to and 

across the West Shore Eailroad tunnel, as shown in 

Figs. 13 and 19.

\^ 5 The first indications of the Bergen Hill fault, as it 

maybe conveniently designated, are in BayonueCity, 

on Bergen Point, where a narrow strip of sandstone 

is obscurely exposed, extending along the center of 

the trap outcrop and apparently protected from erosion by the fault scarp. Southward from this exposure a strip of red soil extends for several miles, 

and northward a depression soon begins which 

crosses tlie Morris Canal cut as a break in the continuity of the trap walls. At the next section across 

the hill, in the cut of the Newark and New York Eailroad, the line of fault is indicated by a wider and 

deeper break in the walls than at the canal, while in 

the cuts of the Pennsylvania Eailroad the break is 

700 feet in width, and was found to be underlain by 

thinly bedded sandstones dipping towards the trap 

§- wall on the western side. Cook, in the Geology of

*; New Jersey and on the accompanying map, called 

g attention to the occurrence of the sandstones in the 

P. Pennsylvania Eailroad cut; and again, on the map of 

I 1874, sections are given in which the trap of Bergen 

| Hill is represented as two sheets separated by sedi- 

§ mentary beds. Eussell, in his paper on Hudson

 s County, concurs in this opinion, but Davis, in his 

08 paper on the Triassic trap and sandstones of the east- 

°2 *ern United States, suggests that the sandstones may 

8 owe their presence to a fault similar to the one in 

Garret Eock.

A half mile north of the Pennsylvania Eailroad 

cut, in the two tunnels, the line of fault is marked 

by a narrow belt of greatly disturbed and decomposed 

trap, and a short distance north of the tunnels thinly 

bedded sandstones were found near the surface in 

excavating for the reservoir. Thence northward for several miles there 

are indications of the continuance of a debris-filled depression, but the 

termination of the fault could not be located. The amount of the dislocation is not known, as it has simply brought down some of the over-
DAUTQN.] PALISADE TRAP. - 43

lying strata on the eastern side, so as to be protected from erosion by the 

fault .vcarp of hard rock, and the absence of outcrops of inclosing strata 

on either side of the trap sheet renders the exact relations undeterminable. The foregoing section (Fig. 18) shows the position and nature of 

the fault in the Pennsylvania Railroad cut.

The absence of sandstones in the tunnel sections is ample proof that 

the trap is not in two sheets separated by a layer of sandstones, aiid 

that the amount of the fault is not sufficient to bring up the underlying 

strata. On the above figure are also shown the supposed relations of 

a small trap outlier in Jersey City, locally known as Fairrnount. Its 

length is only a few hundred yards, and it is completely separated from 

Bergen Hill by tide marsh. Russell, iu his paper on Hudson County, 

suggests that it is due to a local anterior intrusion from the palisade 

trap mass, but it is now better exposed for study, and appears to be 

part of the edge of the main trap sheet separated by a fault, as shown 

in the figure.

 A short distance north of Hoboken the prominent King's Point is 

at the southern termination of an anterior trap ridge, which thence extends for several miles northward, and finally coalesces with the main 

ridge. The intervening depression holds the little Awiehawken Creek 

which rises near Guttenberg, flows through a marsh-filled depression for 

some distance, and thence down a narrow and deep.ravine to empty 

into the Hudson just below King's Point. In his memoir on Hudson 

County, Russell appears to consider this anterior ridge due to the 

change of horizon of the base of the trap, which takes place at its southern end, or to its bifurcation; and Davis, in his paper on the triassic 

traps and sandstones, page 270, suggests that it is due in part to the 

resistance to erosion offered by an increased thickness of the trap sheet, 

possibly aided by a fault similar to the one at Garret Rock, Paterson. 

The finding of shales in the ravine back of the ridge, and in the tunnel 

below the marsh-filled depression, affords an entirely satisfactory explanation of the structural relations which are shown in Fig. 19, and 

also in Fig. 13, p. 37.

FIG. 19. Cross-section north of Weehawken, New Jersey, at H - - - C. on Fig. 21, looking north.

The strata in the ravine are continuous with those underlying the 

main ridge southward, which are observed to abut against the trap of 

the back of the anterior ridge, and in the tunnel two miles farther north 

the same relations exist. In the ravine at W, Fig. 19, a well was driven 

125 feet into the indurated shales without meeting trap, which is ample
44 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

proof that bifurcation or longitudinal change of horizon has not taken

place. The extent of this fault is not 

known beyond the limits shown in Fig. 21 j 

southward it may pass either east or west 

of the serpentine of Castle Hill, Hoboken, 

but northward it probably dies out towards 

Guttenberg. Near Piermout there are 

some suggestions of a fault diagonally 

from southwest to northeast with downthrow on the eastern side, but its presence 

could not be established.

In the great hook farther north, near 

Haverstraw, the ridge is crossed by two 

depressions, the "Long Clove" and the 

" Short Clove," of which the topographic 

configuration suggests dislocation, but no 

positive evidence of faulting could be obtained.

Thickness. There are few localities in 

which the thickness of the palisade trap 

sheet may be satisfactorily estimated, for

* there is a continual possibility of longing tudinal faults, and when the dike structure 

I extends to the country level more cr less

* of the upper part of the sheet has been removed by erosion. Bearing in mind the 

Bergen Hill fault and supposing the underlying sandstones to be at tide-water level 

with a gentle dip westward, which no doubt 

is approximately the case, the thiekness of 

the sheet at the latitude of Bergen Hill 

would be about 300 feet. Near Weehawken, as shown in the tunnel section, Fig. 

13, p. 37, the sheet is apparently 400 feet in 

thickness and the amount appears to gradually increase to about 700 feet near the 

State line. Near Piermont there is a considerable decrease for a short distance, and 

then an increase to 800 or 850 feet, but as 

the entire surface of the sheet is exposed 

to erosion in this region the thickness was 

greater originally. In the Hook Mountain 

the thickness is probably near 600 feet on 

the average, but varies, and there is not 

less than 850 feet of trap in the escarpment

m

"^\r.v

at High Tome. Farther westward the thickness gradually decreases,
PALISADE TRAP. 45

and it is not over 200 feet at Ladentowu and about 30 feet at the terminal outcrop.

Relations to underlying strata. Exposures of the base of the palisade 

trap are frequent along the Hudson River from north of Hobokeu to 

Haverstraw and many details of its relations are exhibited. The sedimentary rocks at the contact are generally the argillaceous shales overlying the basal arkose, and they are in most cases greatly increased in 

hardness and darkened in color for many feet from the trap. The two 

rocks are always welded together along the contact, although the line 

of junction is frequently weathered out, owing to an increased tendency to decomposition which exists at the contact in some localities. 

Descending plates and dikes of trap are of comparatively frequent 

occurrence and slight irregularities, in which the trap breaks across the 

ragged edges of the strata for a shortdistance are found in nearly every 

exposure.

The first outcrops of underlying strata are north of Hoboken, where 

the contact line gradually rises above tide-level, and is entirely conformable to the stratification of the highly altered shales. Owing to the dip 

of the strata and the trend of the. outcrop, a considerable altitude in

FIG. 21. Map showing the relations of the palisade trap north and 

northeast of Hoboken, New Jersey.

the cliff is soon attained, when, as also noted by Eussell, the trap 

breaks abruptly across their edges and descends about 180 feet, as 

shown in Fig. 20 at the locality indicated by E in Fig. 21.

The cross-contact is an exceedingly ragged one, the trap penetrating 

the shattered edges of the shales and including some of their great
46 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

fragments for some distance. Owing to the increased thickness of the 

harder rock, the escarpment advances eastward for several hundred 

feet, forming the bluff on which the "observatory" is built. At the 

southeastern corner of this bluff the underlying strata again emerge 

from below the surface, as shown in the right-hand corner of Fig. 20, 

and are theuce exposed for some distance northward. Around the eastern side of the bluff to the "100 Steps" the trap lies on the arkose 

along an irregular contact plane, one of the most noticeable irregularities of -which is exposed along the road below the " 100 Steps." This 

arkose is slightly altered to a hard gray rock near the contact, and a 

short distance south of the " 100 Steps " it is penetrated for a few yards 

by a trap sheet five feet below the main mass and about a foot in thickness.

North of the " 100 Steps " the ravine described on page 43 extends 

up into the ridge, and the line of escarpment offsets to the shore of the 

Hudson Eiver at the prominent headland of King's Point (at C on 

Fig. 21).

At the southern end of this point the bluffs are trap from base 

to summit, but a few rods northward the base of the sheet comes up 

from tide water level, below which it was carried by the fault described 

on page 43, and crosses the strata as shown in PI. V.

FIG. 22. Contact of trap and indurated shales in entrance to West Shoru Railroad tunnel. \Venawken, New Jersey. Looking soutli. From a photograph.

In this ascent the trap ascends to approximately the horizou at which 

it was first observed below the " observatory," and this relation is apparently preserved for many miles northward. As the ascent is lateral 

to the course of the trap it probably extends into the ridge for some
U. S. GEOLOGICAL SURVgV BULLETIN NO. o? PL. v

LATERAL ASCENT OF BASE OF PALISADE TRAP ACROSS EDGES OF STRATA IN KING'S POINT, WEEHAWKEN, NEW JERSEY, LOOKING WEST.

From panoramic photograph.
BARTON. J PALISADE TRAP. 47

distance, and on the west side of the fault, in the ravine, there are some 

indications of its presence, but the exact relations are not exposed.

The unconformity at King's Point is described and figured by Russell 

1880, Cook 1882, and Davis 1883, and Eussell suggested that it might 

be due to bifurcation of the mass in which an anterior sheet had extended eastward, but the ascent is entirely lateral and the well boring 

near the fault referred to on page 43 shows that no bifurcation has 

taken place.

The small trap sheet shown in PI. V is an offshoot from the main 

mass, and extends for about half a mile noithward, preserving a uniform horizon throughout, with the exception of some slight local irregularities.

At theeastern entrance to the West Shore Railroad tunnel, two miles 

north of King's Point, there is a fine cross-section exposure, showing 

the relations of the trap to the underlying strata, as shown in Fig. 22.

Northward from the tunnel for some distance outcrops are infrequent, 

but the line of contact appears to remain essentially unchanged in position until near Guttenberg, where there are some indications of either 

a slight fault or a change of horizon. The relations at this point are 

not determinable on account of the drift and debris, and a slight local 

decrease in dip may be the cause of the apparent irregularity.

In the road below the quarries of Guttenberg there is a dike in the 

arkose underlying the trap, exposed as shown in the following figure:.

 -r "^ -' //,;>.T^ - ^ -- yr^^-.^. _ _ . '-^_- -^~vr " " *>Zs : "^~-^ ~~ ,-rr3^"".r»-r^,m;^<:?5K .. -^-^ -r =-'^f^_ --- ----^0^

FIG. 23. Dike in arkose below the quarries at Gnttenberg, Kew Jersey. 

Looking northwest. From a photograph.

This dike appears to be connected with the palisade trap, and is a 

precisely similar rock, but whether it is an ascending dike or an offshoot from the trap above is not known.

At Fort Lee landing there is a break in the continuity of the crestline, a shallow depression extends up into the ridge, and the line of 

escarpment offsets several rods to the eastward to form the "Bluff" 

which marks the beginning of the palisadal front, thence extending
48 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

northward uninterruptedly beyond the State line. Near the lower 

<md of the depression behind the " Bluff" there is an obscure exposure 

in the road-side, in which the trap breaks down across the edges of the 

intensely indurated shales and the base of the sheet in the " Bluff" is 

apparently about 75 feet below the horizon, which it held southward. 

It seems probable that in this instance there is a descent of the trap 

laterally across the edges of the shales for some distance, as in the 

King's Point exposure, for there are no indications of a fault in the 

depression, and the dip remains unchanged throughout in the exposures 

toelow along the river.

From the bluff northward to the State line there are numerous exposures of the contact and its vicinity, but there is no evidence of noteworthy irregularity. Near Sneden's Landing, a mile north of the State 

line, a change in trend of the ridge to due north brings the contact line 

to tide-water level, and the underlying strata are not exposed again until 

at Piermont where they reappear conformably underlying the trap. 

Just south of the village the base of the sheet appears to have ascended 

across the strata for some distance, but the exposures are obscure and

 some local changes of dip or a small fault may cause the apparent 

change in position.

In the road just above Upper Piermont the base of the sheet is exposed for some distance and sends a small offshoot obliquely downward 

.and outward into the sandstone for twenty or thirty feet. Another similar occurrence of this kind is exposed in a quarry behind Haverstraw, 

where two small offshoots extend obliquely into the underlying strata 

and terminate by thinning out. From Piermont northward for some

 distance the contact is high above the river, but near Nyack the strike 

gradually attains a direction west of the trend of the ridge, and although 

outcrops near the contact are not exposed for two miles the altitude of 

the base of the sheet probably decreases.

North of Nyack the trend rather abruptly changes to the northeastward, and in the prominent Hook Mountain the escarpment regains the

shore of the Hudson, exposing 

the underlying strata up to a considerable elevation above the 

river. Whether or not there have 

been irregularities in the contact 

line in the two miles of debriscovered interval is not known, 

but the trap has not changed its 

horizon in the formation to any 

considerable extent.

Northward along the river the 

contact is easily traceable, and 

retains a uniform altitude for 

about two miles, when it comes down about 30 feet to tide-water, and so

io. 24. Lateral ascent of the base of the palisade 

trap across edges of strata, two miles north of 

Nyack, New York.
DARTON.] PALISADE TRAP. 49

continues for about 500 feet, to ascend again to approximately its original position. The transverse contact is exposed at the northern end of 

the irregularity, having the relations shown in the preceding figure.

At Bockland Lake some distance northward, another ii regularity of 

similar character is indicated, and a small exposure of ragged uucomformity was exposed below the landing in 1884, but otherwise its vicinity 

is heavily covered with debris and talus.

About half way between Kocklaud Lake Landing and Haverstraw 

there is a small trap sheet in the arkose thirty or forty feet below the 

palisade sheet, and its relations are shown in the following figure :

FIG. 25. Trap sheet in arkose under palisadr ii'ap. on tin- shore of Hudson llivei. I'our miles south of 

Haverstraw, "Sew York, looking west. From a photograph.

This anterior sheet varies in thickness from 3 inches toa foot, and may 

be traced for a short distance from the locality shown in the figure. The 

rock is a fine grained diabase, and has not altered the inclosing arkose 

to the least degree, but on the contrary the trap is slightly vesicular at 

some points along the contact.

The relations of the palisade trap to the underlying strata in the 

region of the great hook near Haverstraw are not well exposed, and 

there is considerable uncertainty in regard to the position of the contact and its changes of horizon. In discussing the structure of the 

region it is stated that the course of the sheet was not determined by the 

structure of the inclosing stata, as in the hooks of the Watchung MountBull. 67 4
50 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

aius, but by the crescentic course of the dike, aided to a considerable 

extent by the structure, but attended by unconformities by which a 

change of horizon is effected aggregating at least several hundred feet. 

Owing to the talus and debris, none of these unconformities are exposed, 

but at some points the base of the sheet is seen lying with perfect conformity on the sandstones which strike in some cases parallel to 

the trend of the ridge, and in others to the west-northwest. Between 

the West Shore Eailroad tunnel and the foot of the High Torne the 

base of the sheet appers to ascend at least 150 feet, while just behind Haverstraw its base is 200 feet above the river, or approximately 

300 feet above the position the contact -would have held if it had followed the dip in this vicinity. As before suggested, it is possible that 

these irregularities are due in part or entirely to faults passing through 

the Short Clove and the Long Clove. These " Cloves" are deep depressions extending across the ridge, and they are approximately at the 

points where the changes of level take place.

West of Haverstraw the underlying strata are not exposed within 

half a mile of the trap until near Tlieils, where, as before noted, some 

pebbly conglomerates on the roadside dip gently southward directly 

under the edge of the sheet, and this conformable relation may prevail 

along the entire northern side of the hook. In the wide gap at Mount 

Ivy the surface of the sheet is at country level, probably being brought 

down by the marginal synclinal which crosses it in this vicinity. To 

the southward, underlying strata again come up, dipping gently to the 

southeastward with perfect conformity under the sheet, but not exposed 

in actual contact. Near Ladentown the calcareous conglomerate is exposed near the trap, but it presents no sign of alteration, and the pebbly 

conglomerates exposed within two feet of the trap farther southward 

are entirely unaltered.

Relations to overlying strata. Owing to the extensive denudation to 

which the surface of the palisade trap has been subjected, overlying 

strata seldom extend far up its inner slope, and they are generally 

either removed down to the level of the detritus covered plain westward, 

or hidden by the heavy masses of drift which often extend for long distances along the western side of the ridge. There are, however, a sufficient number of scattered exposures along its course to indicate the 

structure of the trap and throw some light upon the mechanism of its 

intrusion.

Iii New York the only exposures of overlying strata are near the northwestern termination of the trap outcrop, where the relations shown in 

Fig. 17 prevail, and in a small outcrop of highly indurated, gently westdipping shales, halfway up the slope, in the road from Valley Cottage 

station to North Nyack. Elsewhere the trap either slopes gently down 

to the level of the back country, as in the vicinity of Eockland Lake 

and across the ridge from Nyack, or forms steep, rugged slopes having 

greater inclination than the dip of the strata in the adjoining outcrops,
PALISADE TEAP. 51

and indicating the extension above the surface of the dike portion of 

the mass. These steep, inner slopes are very conspicuous along the 

east-and-west ridge, southwest and west of Haverstraw, where the sandstones near the trap dip at very low angles to the westward, and southeast of Nyack, where similar conditions prevail to within a couple of 

miles of the State line, although in these instances the possibility of 

faulting is not entirely out of the question. In the cut just south of 

the West Shore Bailroad tunnel, south of Haverstraw, there is a fine 

exposure of the back of the dike crossing the shales, as shown in the 

following figure (Fig. 26), and indicating the structure shown in Fig. 

14, p. 37:

FIG. 26. Exposure of back of dike of palisade trap in cut at southern entrance to West Shore Kailroad 

tunnel, 3 miles south of Haverstraw, New York, looking west. From a photograph.

A short distance west of the tunnel a small area of intensely indurated shales is exposed in the roadside at the base of the ridge, and 

dips away from the trap nearly vertically, being apparently flexed to 

conform to the side of the dike.

For many miles southward from the State line into Kew Jersey the 

dike of the palisade trap does not appear to reach the present surface, 

and along the western slope of the ridge the sheet is overlain with essential conformity by highly indurated shales and sandstones. Two miles 

east of Closter is a series of exposures of indurated strata near the 

trap, in which only slight local unconformities are apparent, and on the 

road from Closter to Alpine a perfectly conformable contact is exposed.
52 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

Davis describes the locality in the stream bed near Floraville, south 

east of Englewood, where the indurated shales are exposed in conformable contact with the trap, and a mile south, near and on the road from 

Leonia to Fort Lee, there are numerous small, thin patches of intensely 

indurated shales lying on the surface of the sheet.

Along a stream, about a mile northeast of Granton, there is a fine 

exposure of the strata immediately overlying the trap, and although 

the exact point of contact is not exposed, considerable unconformity 

exists both in dip and strike, probably indicating the presence of the 

dike. Two miles farther south, the back of the dike is exposed in the 

cut of the West Shore Eailroad, as shown in the following figure (Fig. 

27), and having the relations shown in Fig. 13, p. 37.

PIG. 27. Exposure of back of dike of palisade trap in cut at western entrance to West Shore Eailroad 

tunnel between New Durham and Weehawken, New Jersey, looking north. From a photograph.

In this exposure the strata are inclined to the northwestward 10 

degrees, and the back of the dike slopes west-southwest > 60 degrees, 

so that the course of the dike is oblique to the strike of the strata. The 

rock in contact with the dike at this locality is arkose, greatly shat 

tered at most points and considerably disintegrated, owing to the decomposition of its feldspathic constituent, but in places there is a welded, 

ragged contact showing unmistakably that the sharp break is not due 

to faulting. Between New Durham and Homestead Station (Schuetzen 

Park) the course of the dike is bowed eastward, as shown in Fig. 21 

and on PI. I, and its northwestwardly trend in the West Shore Railroad 

cut is part of this deflection, which may be connected with the change 

in horizon of the base of the sheet, on the other side of the ridge at 

Weehawken, as described on page 46.

In the small quarry, near the base of the hill, about 500 yards southeast of Homestead station, there is found the last exposure of overlying
DABTOJC.J UNION HILL TRAP. 53

strata in New Jersey, in a mass of highly indurated, gently west-dipping shales, welded to the trap along a conformable contact line, indicating the extension of the sheet westward again to the base of the hill, 

and the descent of the dike below the surface. Opposite Jersey City 

the gentle trap slope extends down to the marsh or drift deposits, and 

on Bergen Point is the shore of Newark Bay. On the northwestern 

corner of Staten Island, and on a small island in the Kill opposite, there 

are exposures of unaltered, overlying, thin-bedded sandstones, dipping 

at a low angle westward, but they are at some distance from the trap, 

and nothing further is known of their relations.

As stated on page 42, there is a strip of overlying shales extending 

along the fault line up Bergen Point to the reservoir in Jerse}' City. In 

the exposures at Bayonne City Pennsylvania Eailroad cut and the reservoir, they are entirely unaltered in texture or color, but are not exposed 

near their contact with the trap.

Oil the southwestern corner of Fairmount, in Jersey City, just east 

of Bergen Hill, there are some thin, irregular streaks of sedimentary 

material mixed with the trap, probably remnants of overlying strata, 

but the means by which they were included and their source are not 

known.

UNION HILL TRAP.

A short distance northeast of Suffern, New York, there is an isolated 

trap ridge very near the western border of the formation. It rises 150 

feet above the surrounding country, and presents its steepest face to the 

eastward. It is in line with the north westernmost outcrop of the palisade trap, as shown on Fig. 16, and is possibly due to an extension of 

that sheet brought up again by flexure or change in horizon. Its structural relations, so far as known, are shown in the following figure:

PIG. 28. Section across Union Hill, northeast of Suffern, New York. Looking north. T, trap of 

TJnioii Hill. C, conglomerate. SS, sandstones. G, gneiss. L, limestone (?).

No overlying strata are exposed, and the underlying rocks are heavy 

beds of quartz conglomerate, extending up to about 100 feet above the 

plain on the eastern side of the ridge, and dipping W. > 10°, under 

the trap sheet. The thickness of the latter is about 100 feet. It is a 

moderately fine grained diabase, presenting no evidence of vesicnlarity 

at any point, and rather more like the intruded traps than those extrusive in nature. The manner in which it terminates north and south and 

its exact horizon in the formation are unknown.
TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

GRANTON TRAP.

Midway between Jersey City and Hackeusack a small, intrusive trap 

mass constitutes a short ridge just across the turnpike from the western 

slope of the Palisade Mountain, and lying parallel with it. In Fig. 29 

its areal and apparent structural relations are shown. Its striking resemblance in structure to the palisade trap is one of the most interesting features.

/

i«

^^^^^yf^^A^^^^n^^^^^.

FIG. 29. Map and sections showing relations of Granton trap to Palisade trap.

On the steep western side of the ridge the back of the dike is exposed 

in the West Shore Eailroad cut, breaking almost vertically across the 

shales, of which only a small mass remains. On the eastern and northeastern sides the sandstones separating this trap from that of the Palisades dip northwestward conformably under the edge of the sheet. 

On the southern side of the ridge there are no outcrops. No overlying 

strata remain on the sheet and its outcrop terminates northward, southward, and eastward in escarpments, so that its former extent and therelations of its original north and south edges to the dike and the inclosing strata are not determinate. As its inner side is not exposed at 

either end of the ridge, the thickness of the dike is not known, and as 

there are no traces of its extension to the north or south it probably 

-terminates within the present trap-covered area.

The rock of the posterior ridge is a moderately fine grained basalt, 

very similar to much of that of the adjacent palisade mass. It is dense 

and homogeneous throughout and presents no traces of vesicularity. 

The adjacent shales are greatly altered, and the trap is fine grained at 

the contact and welded to the sedimentary material. The thickness of 

the sheet now remaining is probably near 125 feet, but as the entire 

surface has been eroded more or less deeply, the original thickness may 

have been considerably greater,
DARTOS.l SNAKE HILLS TRAP.

SNAKE HILLS TRAP.

55

Big and Little Snake Hill are two knobs rising abruptly from the 

tide marsh some distance west of the inner slope of the palisade trap in 

Bergen Hill, near the latitude of Hoboken. The smaller hill is a trap 

outcrop covering a few acres to a maximum height of 76 feet, and nothing is known of its structural relations. The larger hill is half a mile, 

farther west, along the eastern shore of the Hackensack Eiver, and 

covers approximately a square half mile. Its elevation varies between 

125 and 200 feet, and its central mass of trap is flanked in part by small 

remnants of sandstones and shales. It has steep slopes on all sides 

but the northern, which is drift-covered and gradual, and its structural 

relations are quite similar to those of the Granton ridge.

FIG. 30. Stereogrammic map and sections of Snake Hill, New Jersey.
56 TEAPS OP THE NEW JERSEY REGION. [BULL. 67.

The trap forming the precipitous eastern side of the hill is a sheet 

with an irregular bedded structure, underlain southward by sandstones 

and shales which dip N. 30° W. > 14°, in the railroad cut. On the 

northern side of the cut the contact with the trap is exposed, and 

the line of junction, though somewhat ragged, is essentially conformable to the bedding. The dip soon carries the underlying strata beneath the surface westward, and the southwestern corner of the hill 

is entirely trap. On the western slope the sandstone and shale outcrops begin again as shown on the map, Fig. 30, and extend northward 

to the drift mantle, which obscures all bat the trap boundary to the 

north and northeast. In the quarry near the southern termination of 

these sandstone outcrops the edges of the strata are exposed abutting 

against the back of the dike which rises along the western slope of the 

hill to join the sheet, which thence appears to extend eastward as shown 

in the cross-section. Formerly this unconformity was finely exposed 

at the center of the quarry, as shown in the following figure (Fig. 31),

but in 1886 the only exposure was an 

obscure one in the northern end of 

the quarries.

The dips in this vicinity are N. 20° 

W.>15°, and at some points the disturbance is considerable in amount. 

The extent, thickness, and exact 

relations of the dike are uncertain, 

for its inner side is not exposed, but 

it does not appear to extend north 

and south beyond the area of the elevation, and probably is not over 20 

or 30 feet thick at the greatest. The 

sheet is undoubtedly intrusive, as shown by its ragged contact with the 

shales in the railroad cut arid by the alteration of the strata in the immediate vicinity of the sheet wherever exposed. The Snake Hills trap 

is exactly similar to the typical Palisade rock, and it has been suggested 

by Credner and by Eussell that it is a posterior offshoot from the same 

mass. As the entire surface of the sheet has been exposed to erosion, 

the original thickness is not determinate, but there now remains about 

200 feet, which is in greater part above country level.

ARLINGTON TRAPS.

Along the eastern slope of the sandstone ridge which bounds the 

Hackensack meadows, three miles west of Snake Hill, there are several 

small trap sheets, the extent of which is shown on Fig. 32.

Beginning at the south, the first exposure is in. a small opening just 

north of the railroad, where the edge of a sheet six feet in thickness is 

seen conformably intercalated between beds of coarse sandstone, which

FIG. 31. Partial cross-section at one time exposed in western side of Snake Hill, showing 

the back of the dike. Looking north.
ARLINGTON TRAPS. 57

are not perceptibly altered in its vicinity. A few rods farther north, at 

A on the map (Fig. 32), the edge of this sheet was exposed again in

FIG. 32. Map of the region near Arlington and the Schuyler 

copper mine, north of Newark, New Jersey.

excavations for copper in Westlake's quarry, and its relations are shown 

in the following figure:

FIG. 33. Cross-section at A on Fig. 32, in Westlake's quarry, looking north. The black blotchings 

and dottinga represent seams and impregnations of copper ores, a, trap sheet; b, sandstone; c, 

shales.

The writer was present during the uncovering of the trap, and 

sketched all the details shown in the figure. The sheet has forced its 

way forward near the junction of shales and sandstones, lifting the latter, and probably causing the fissures which hold the plates and bunches 

of chalcocite. The trap is a fine grained, dense, bluish gray rock, five 

feet thick, and with smooth surfaces to which the strata were generally 

found welded. The adjoining shales are intensely altered, but the alteration only extends for a few feet from the trap.

Beginning in the cemetery and thence extending northward for about 

a mile, a trap sheet is exposed at intervals to the old Schuyler copper
58 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

mine, and may be an extension of the sheet just described. At B on 

the map it is associated with two smaller trap .masses apparently having the relations shown in the following figure, the dike ascending along 

a line of fault and sending off a small sheet eastward :

JTiG. 34. Cross-section of trap outcrop in cemetery at Arlington, New Jersey. At B 011 Fig. 32, looking north.

The main sheet in this vicinity is exposed in contact with sandstone, 

in which it is conformably intercalated, and there is comparatively little disturbance in the bedding or alteration in color or texture. North 

of the cemetery the edge of the sheet forms a mural escarpment along 

the turnpike, and its thickness is increased to 20 feet. A short distance 

westward in this vicinity there is a small sheet in the overlying strata, 

which crosses the road as shown in the map. After crossing the turnpike the main sheet pitches beneath the surface and forms the floor of 

the old Schuyler mine, which sends a net-work of galleries through the 

cupriferous sandstones near the contact. It was hoped that in this 

mine the structure of the trap could be studied, but the workings were 

found to be fallen shut in the parts of greatest interest, and the edge of 

the sheet could not be reached. Generally in the mine the surface of 

the sheet is smooth and comformable to the gently dipping sandstones, 

but there are irregularities in which the strata are crossed for a few feet, 

and the sheet sends several offshoots up into the sandstone. It is stated 

that the trap surface was followed westward for a half mile in the mining 

operations, and that at one point it is traversed by a fault of considerable amount. It is possible that this fault is an extension of the one so 

finely exposed in the New York and Greenwood Lake Eailroad cut, 

near Arlington, and shown in the following figure :

FIG. 35. Fault exposed in cut for New York and Greenwood Lake Railroad, west of Arlington, New 

Jersey, looking nortli. From a photograph.

Cook and Eussell have described some features of this fault, and its 

amount has been estimated at about five feet, but after a very careful
DAKTON.] LAWKENCE BROOK TO JERICHO HILL TRAPS. 59

reexamination of the monotonous succession of sandstones and shales 

on either side, the writer is convinced that it may be much 

greater. The disturbance is considerable, and a width 

of from 6 to 8 feet is occupied by fault-rock composed of 

slickensided fragments, coated with chloritic matter, calcite and quartz. The hade is 20 degrees to the westward 

and the down-thrown side appears to be the eastern. 

The trend is north-northeast and south-southwest, as 

shown on the map, and although the fault is not traceable 

on the surface, it very likely extends to the Schuyler 

mine. Russell considered the fault-rock of this dislocation the result of metamorphism, which is also stated to 

extend for some distance on either side, indicative of the 

presence of trap below, but, excepting the coating men 

tioued above, the rock is not altered in appearance, and 

its hardness is not perceptibly increased.

LAWRENCE BROOK, TEN MILE RUN MOUNTAIN, 

ROCKY HILL, PENNINGTON MOUNTAIN, BALD 

PATE, AND JERICHO HILL TRAPS.

A series of trap outcrops extends from the Cretaceous 

border six miles southwest of New Brunswick, westsouth westwardly, diagonally across the southern corner 

of the New Jersey Newark area into Pennsylvania, a distance of 25 miles. They are in the region to which I have 

given the least attention, and their structural and stratigraphical relations are not well exposed for study. Pis. 

I and VI and Fig. 37 indicate the position and extent of 

the several members of the series, and their relation to 

the palisade trap was discussed on a preceding page.

With the exception of the Lawrence Brook outcrops, 

which are at country level, the traps of the series give 

rise to sharply defined ridges, rising three or four hundred feet above the red shale country, and consisting of 

a thick trap sheet, more or less heavily flanked by the 

highly altered, gently west-dipping strata into which it 

was intruded.

In the gap by which the Milliugton River crosses Rocky 

Hill at Rocky Hill Station there is a typical cross-section 

exposure in which the relations are as shown on the right 

in Fig. 36.

Whether or not the breaks in the line of outcrop that 

isolate Pennington Mountain are due to discontinuity 

in the trap is not definitely known, but the sheet is probably continuous, and its presence under the surface indicates the belt of altered shales in the intervening gaps.
60 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

The trap is uniform in character throughout, being in greater part a 

coarse grained, blue gray rock, similar to that which predominates ia 

the palisade outcrop, and similarly fine grained and bedded in structure near its contact with the sedimentary rocks. The latter "are always 

more or less highly altered, frequently for a hundred feet vertically 

above the sheet, and this alteration is especially noticeable and interesting at the copper mine near Griggstowu, Rocky Hill gap, and Lawrence Brook, as described by Rogers and Cook. There are a number, 

of irregularities in the course of the Lawrence Brook, Ten Mile Run 

Mountain, and Rocky Hill trap which are not entirely due to changes 

in structure of the inclosing strata and a progressive ascent westward, 

in its horizon in the formation; for at Lawrence Brook the sheet lies 

near the basal beds at the Cretaceous border, and at Hopewell, 1,000 

feet higher if faults do not intervene. In the following figure (Fig. 

37) these features are shown, and it will be seen that the trap crosses 

the strike for some distance south of Hopewell, and at the northwestern end of Ten Mile Run Mountain.

FIG. 37. Map of Rocky Hill, Ten Mile Run Mountain, Lawrence Brook trap and vicinity.

Unfortunately I did not have an opportunity to study the question 

in detail, and do not know whether the unconformities are exposed in 

the shales which underlie the trap along the southern slope of the ridge, 

or in those on its other side. The structure of the crescentic outcrop 

east of Rocky Hill is not definitely known, and while its form is very 

suggestive of a cross synclinal or of centroclinal flexure, it is apparently 

due to a bifurcation of the sheet or of the course of its feeder, and progressive changes of horizon in the trap at the southern part of the 

Ten Mile Run Mountain.

In the interval between the western end of Rocky Hill and Pennington Mountain the strata are considerably disturbed in position and 

altered in color and texture. At its westernmost exposure the Rocky 

Hill trap thins out and pitches beneath the surface, apparently to pass 

over the point of a low northwest pitching anticlinal and reappear in 

Penningtoii Mountain, as suggested by the dotted Hues in PL VI.
DABTON.] SOURLAND MOUNTAIN TRAP. . 61

Penuington Mountain consists of a trap sheet, conformably capping 

northwest dipping, altered shales, which extend up its steep eastern 

side and flank its western slope. The trap thins south west wardly and 

retreats down the dip to sink below the surface, but probably reappears 

again in Bald Pate. This irregular ridge is similar in structure to Pennington Mountain, but is apparently traversed by a fault or flexure 

causing its wide, northern lobe. The trap of Bald Pate reappears on 

the Pennsylvania side of the Delaware as Jericho Hill, the hooked 

termination of which is due to flexure, as described by Lewis, and indicated in PL VI.

SOURLAND MOUNTAIN TRAP.

This great intruded sheet and its heavy flanking of indurated shales 

constitute the prominent flat topped mountain extending from ^eshauic 

to the Delaware Eiver, and thence into Pennsylvania to the great medial fault which cuts it off very near its natural termination. Throughout its course the ridge rises steeply to about 200 feet above the adjacent plain, with a width averaging near four miles, and with both slopes 

approximately the same in inclination. The trap outcrop occupies the 

center of the elevation, varying in width as shown in the map, and the 

belt of hardened and darkened sedimentary rocks forms the edge of the 

plateau and the corrugated slopes.

Along the Delaware, south of Lambertville,the trap sheet is finely 

exposed in cross section, and the following figure shows its relations to 

the associated strata and to the other trap sheets of the Delaware Eiver 

region.

FIG. 38. Section along the northeast side of the Delaware River from Titusville to Stockton, New 

Jersey, on line L K, Plate VI. O, lower Paleozoic limestone overlain by basal Newark conglpmerateand sandstones.

In the main, the trap-sheet preserves essentially the same horizon 

throughout, but east of Eiugoes there is a sharp deflection in the line 

of outcrop, which is due to a temporary change of horizon, amounting 

to about 250 feet vertically, and slightly aided by flexure.

The strata inclosing, the sheet dip to the northwest in the main, at 

angles between 12 and 18 degrees, the principal variation being near 

the northern end of the ridge, where the dip is only about 5 degrees and 

the width of outcrop correspondingly increased, and along the Delaware, where the amount is about 22 degrees. A singular feature in the 

^structure of the Sourland Mountain trap sheet is the comparatively 

.greater inclination of the strata on its western flanks than that of the
62 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

underlying beds and those in the plain country to the westward. This 

structure is not apparent throughout the course of the ridge, but is the 

most noticeable between the deflection near Kingoes and its northern 

. termination. East of Kingoes the dips are at first 10 to 12 degrees, but 

as the slope of the ridge is ascended they progressively increase finally 

to 25 degrees, while on the eastern side the amount is about 12 degrees 

throughout. It seems probable that this increase in dip indicates the 

structure shown by the dotted line A in the following figure, but it is 

also possible that it is due to a general longitudinal flexure, as shown 

byB.

aooo rr

FIG. 39. Section across Sourland Mountain from Kingoes to Snydertown, New Jersey, on line C X>

PI. VI.

The thickness of the Sourland Mountain trap appears to be generally 

near 700 or 800 feet, but along the Delaware the amount is nearly 1,500 

feet if the sheet is not traversed by faults. Its northern termination 

near Neshanic is due to thinning out, and the mechanism of its increase 

in thickness southward is not known, as it may be due either to wider 

separation of the inclosing beds by flexure or to progressive lateral unconformities to their edges. The terminal outcrops in Pennsylvania 

were not studied.

The rock of the sheet is rather coarse grained, except near its contacts,, 

where it is often very fine grained, and is in general very similar to the 

palisade trap and the rock in the ridges to the east and south, it 

appears to be the result of a single intrusion and to occupy a horizon 

considerably above that of the palisade trap.

Contacts of the trap with the inclosing strata were not found and 

would be very dificult to recognize in hand specimens on account of 

the intense induration. This alteration of hardness and color of the 

ghales is one of the most characteristic features of the ridge, and it is 

due to their hardness that the altered beds constitute so considerable 

a portion of its flanks. The alteration seldom extends for less than 

200 feet above the trap, and 30 or 40 feet below, but generally prevails 

in both directions for five or six hundred feet vertically. At Lambertville, and on the opposite side of the river as described by Kogers, and 

near Kocktown, southeast of Kingoes, nodular alteration products are 

conspicuous in considerable variety.

TRAP OF CUSHETUNK AND ROUND MOUNTAINS.

Ten miles west of the hooks of the Watchung Mountains is the 

prominent ridge of Cushetunk Mountain, which extends in an irregular
U. 8. GEOLOGICAL SURVEY BULLETIN NO. 67 PL. VI

V tr. 

NESHANlClS

ELEVATED PLATEAU KNOWN AS "THE SWAMP 

AND UNDERLAIN IN GREATER PART BY INDURATED,

SHALES. DIPS; N W 10-20?

RAVEN ROCK__ __ STOCKTON^ 

- //.

t ^^^r&^^'^T^^--

LOWER PALtOZOlC.

MAP OF THE DELAWARE RIVER REGION,
CARTON.] CUSHETUNK TRAPS.

horse-shoe shaped course to the border of the formation, as shown in 

Fig. 40.

LEGEND 

TRIASSIC SHALES.

TRAP.

LOWER PALEOZOIC.

ARCHEAN.

FIG. 40. Stereogrammic map and sections of Cushetunk and Round Mountains and vicinity, New Jersey. A, part of New Germantown trap.

Excepting at its western ends the portion of Cushetunk Mountain 

bordering the inclosed, oblong, red shale valley is of unbroken crest line, 

generally elevated between 650 and 850 feet above tide and having a 

steep inner slope. In its broad lobe southward the slopes are gentle 

to the west and south but steep to the southeast, and a depression 

extends up into the mountain from the westward.

Round Mountain rises pyramidally to an elevation of 608 feet above 

tide, with moderately steep slopes on all sides, and is separated from 

Cushetunk by a depression extending down to 345 feet above tide.
64 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

The structural relations of the region are complicated by flexures and 

irregularities of intrusion, and outcrops of the sedimentary rocks are 

not sufficiently numerous in the vicinity of the traps to yield data for 

the satisfactory determination of all the relations. As shown in the 

cross-sections, the trap appears to have constituted one wide sheet, considerably flexed, and with the form of its present outcrops mainly determined by the removal of the trap from the crests of anticlinals. In 

the northern ridge of Cushetunk the trap is a sheet extending down 

between the strata northward and northeastward for an unknown disdistance in the slightly flexed monocline. In the vicinity of B the sandstones are not exposed within a half mile of the trap, and the relations 

are uncertain, but the inner edge of the sheet comes to the surface in a 

synclinal which begins near that point, and thence with increased width 

and depth, extends westward, as shown in the medial longitudinal section in Fig. 40. Southwest and west from E, around the outer edge of 

the mountain, the strata dip gently beneath the eroded edge of the 

sheet until near C, where the trap pitches beneath the surface, and 

so continues along the wide western border of the outcrop. Just north 

of the center of the cross-section the edge of the sheet comes to the surface again and is exposed, overlapping the bordering Paleozoic limestone for some distance, as shown in the following figure:

10 FT.

~FiG. 41. Contact of Cushetunk trap and Cambrian (?) limestone near Prescott Brook, 2 miles east of 

Allentown, N"ew Jersey. Looking north. From a photograph.

dp the depression just east of this overlap, patches of shale are inclosed by the trap outcrops, but their relation is not exposed, and just 

northward there is a considerable embayment of strata apparently 

below the sheet in horizon brought up by alow, local anticline.

In Bound Yalley the strata are not exposed near the trap, and few 

dips were observed that would aid in determining the relations. On the 

north side of the valley the dips are towards the trap; at the eastern 

end no outcrops are found within half a mile of the ridge; in the center 

northwestern dips prevail, but they become more to the westward south 

of the valley road, and at.one point near the trap the dip is apparently 

steeply to the south westward in an obscure outcrop, as shown by the 

dotted dip-mark in Fig. 40. Notwithstanding the scarcity of positive 

evidence it seems probable that Eouud Valley is an irregular anticline, 

with its axial plane dipping northeastward and pitching northwestward.

The trap of Bound Mountain lies in a well defined synclinal or spoon, 

and is separated from Cushetunk by a local anticlinal shown in the 

cross-section.
DAKTON.] CUSHETUNK TRAP MARTIN'S DOCK TRAP. 65

The Cushetunk trap appears to be an intrusive sheet, as it is undoubtedly unconformable to the inclosing strata at some points, and has 

caused extensive alteration in their hardness and color. In the railroad 

cuts between Lebanon and White House the conformable overlying 

strata are indurated at several points for some distance from the trap, 

and near Stanton the underlying beds are hard and black for a thickness of at least 150 feet. Contacts with the sediments were not found, 

but north of Stanton the line of juncture was only obscured by a narrow 

belt of debris, and might have been discovered by a more careful search 

than 1 had time to make.

The thickness of the Cushetunk trap could be determined even approximately only in the northern part of the ridge, where it averages 

near 400 feet. In the southern outcrops the original thickness of the 

sheet was reduced by erosion, as its entire surface is exposed, but north 

of Stanton the amount is at least 900 feet, if the dip is constant and no 

faults intervene. The surface of the sheet in Eound Mountain is 

similarly exposed to denudation, but a thickness of at least 350 feet of 

trap remains. Near E, and from C northward, the uneroded edge of 

the sheet is very thin, and the northern ridge appears to end westward 

by thinning out near Lebanon.

The Cushetuuk trap is a dense, coarse grained, gray rock, excepting 

at its edge near 0, where it is fine grained and more like an extrusive 

rock in appearance and topography.

SMALL SHEETS IN THE RARITAN RIVER REGION.

Martin's Dock. The occurrence of two thin sheets or trap intercalated in the shales near this point is described and.figured by Cook, 1 

and by Davis, in his Triassic Trap Memoir, page 276 and figure 5'J, 

and in Cook's report for 1882 a photo-lithograph is given of a portion 

of the exposure. I can add but little to this information. The exposure is on the north bank of the Raritau, two miles below New 

Brunswick, and the following figure represents the general relations.

FIG. 42. Cross-section exposure of trap sheets along the Raritan Eiver near Martin's Dock, New

Jersey, looking north.

The upper bed varies in thickness from 18 inches to 2 feet, the lower 

bed from 13 to 15 feet, and the separating strata is generally about (a 

foot thick. The trap is a uniformly fine grained, blue gray rock, slightly 

denser and finer grained at the contact. Its surface and contacts are 

slightly irregular locally, but essential conformity prevails. The alterBnll. 67 5

1 Geology of New Jersey, 1868, p. 202.
66 TRAPS OF THE NEW JERSEY REGION. [HULL. 67.

ation in color and hardness in the inclosing shales is confined to within 

a few inches of the contact on either side, and no evidence of fusion was 

found. The intrusion has caused no noticeable disturbance in the strata 

except a slight breaking or offsetting of the beds at the contact line, and 

the two sheets are entirely separated as far as exposed. No evidence 

could be found bearing on the sequence of their intrusion, and it is 

possible that the separating shaly bed is a local inclusion in a single 

trap mass.

Neiv Brunswick. Cook 1 refers to the occurrence of trap southwest of 

New Brunswick, in the cut of the Pennsylvania Eailroad, and at the old 

Earitan copper mine. The first exposures from the north are in the 

railroad sut, a short distance north of the " straight turnpike," where 

there appears to be a sheet approximately five feet in thickness intruded 

in the shales. The outcrop is an obscure one, and the trap is a mass of 

fragments inclined parallel to the dip of the strata. South of this sheet 

in the cut there is another and smaller trap mass, equally obscure in its 

relations and similarly composed of a fine grained, gray rock. Trap

fragments, apparently representing 

the extension of both of these dikes, 

were found at intervals in the fields 

for a couple of miles to the southwestward, and at the old openings 

of the Earitan copper mine there is 

an outcrop just west of the shaft, 

apparently the northernmost trap, 

and, judging from the fragments, the 

other sheet was pierced by the shaft. 

No attempt was made to trace the 

traps farther southward, aud they 

may possibly be connected with the 

Ten Mile Eun trap, with the western 

arm and outlier of which they are in 

line. Continued northeastwardly they would cross the Earitan about 

at Martin's Dock, and appear to be at the same horizon as the two 

sheets at that place.

FIG. 43. Map of Flemington, New Jersey, and 

vicinity, showing the extent and position of 

the three trap masses.

FIG. 44. Trap sheet just east of Wertsville, crossing road to Stoutsburgh, looking north.

Flemington. In the vicinity of Flemington there are several lines of 

trap intrusion, which are referred to in part by Eogers and by Cook.

Geology of New Jersey, p. 204, and in the report for 1882, p. 59.
DARTON.] FLEMINGTON, WERTSVILLE, AND NESHANIC TRAPS. 67

The principal mass constitutes a ridge just west of the town and extends north and south for less than half a mile, not reaching either the 

Clinton or the Stockton turnpike. The exact rela- ______ 

tion of the trap to the sandstone is not exposed, but 

from the structure and induration of the adjacent 

strata it is thought the trap constitutes a sheet 

thirty or forty feet in thickness, intruded up the 

northwest dipping beds of shales. Parallel to this 

trap and between it and the town are two smaller 

lines of outcrop, having the positions shown in Fig. 

43. The easternmost trap forms a prominent outcrop on the Stockton road near the Pennsylvania 

Eailroad depot, and was also found in the old copper mine near by. An extension of apparently the 

same trap is fairly well exposed in a run just north 

of the Clinton turnpike, where it appears to be a 

thin sheet intercalated in slightly altered shales.

Three miles south of Flemingtou, near Copper 

Hill, fragments of trap in the fields possibly indicate the southward extension of the Flemington intrusions.

Wertsville. Six milesjsoutheast of Flemington, 

and a few rods east of the road from Neshauic to 

Ringoes, there is a trap sheet, which was traced for 

about a mile parallel to the Sourland Mountain 

sheet, and distant from it a mile and a quarter. 

The best exposure observed is on. the road east of 

Wertsville. where the relations are as shown in the 

accompanying Fig. 44.

The thickness of the sheet is about two and a 

half feet, and while the trap is in the main conformable to the west-dipping shales, it crosses them for 

several feet in the exposure. The rock is fine 

grained basalt, considerably decomposed.

Neshanic. In the cut of the Lehigh Valley Eailroad, about half a mile west of Neshauic station, 

there is a cross-section exposure of a small intruded 

trap sheet. Its thickness varies from two to three 

feet, and it is* essentially conformable to the gently 

northwest-dipping strata, although on the northern 

side of the cut it crosses their edges at a low angle. 

The shales are somewhat darkened in color and 

hardened immediately adjacent to the trap, but the ______ 

alteration is not extensive. The intrusive rock is a " 

fine grained, bedded basalt, uniform in texture throughout. It could
68 TRAPS OF THE NEW JERSEY REGION. [BULL. 67.

be traced on the surface for only a few yards in either direction from the 

cut. Its position is shown in Pis. I and VI, and its relations in the accompanying Fig. 45.

SMALLER TRAP MASSES OF THE DELAWARE RIVER REGION.

Point Pleasant. This trap outcrop was alluded to by Eogers in his 

final report on New Jersey, page 150; Cook in Geology of New Jersey, 

page 192, and in his report for 1882, page 63 ; H. C. Lewis in Am. Phil. 

Soc. Proc., vol. 22, page 454, and by Davis, in Triassic Traps, etc., 

page 277. Cook suggests, 1882, that there are two interbedded trap 

masses, and Davis describes the locality in considerable detail, announcing the presence of seven trap sheets, two south of Byrara station, 

one at the quarry just north, and four in a ravine some distance northward. My examinations have convinced me that there is but one trap 

sheet, and the other supposed ones are heavy beds of highly altered 

shales. Several specimens of each were obtained and a microscopic examination showed very plainly the clastic nature of all but the coarsely 

crystalline rock of the conspicuous outcrop south of Byram station. 

This trap is an essentially conformable sheet between 100 and 125 feet 

in thickness, intruded between beds of shales which are altered for a 

short distance below, and for nearly half a mile (500 feet vertically) 

above the sheet. The exact contact of trap and shales was not observed, 

but in a ravine extending east from near Byram there is an exposure 

near the line of upper contact and possibly the junction could be found 

on careful search. The dips throughout are gently to the northwest, 

and there is no evidence of disturbance caused by the intrusion. The 

trap outcrop extends east of Byram about a mile, and southward in 

Pennsylvania, according to Lewis, about five miles. The rock is very 

similar to the typical palisade trap and is fine grained near the contacts 

and coarser in the center. Its general relations are shown in the following section, and its extent and relation to other traps in PI. VI.

Shales. b.J3yram, Station,.

FIG. 46. Cross-section showing the relations of the Point Pleasant trap at Byram, New Jersey,

looking northeast. 

Belle Mountain. Belle Mountain, an abrupt, narrow ridge on the 

east side of the Delaware, between Sourland Mountain and Bald Pate, 

is the edge of a small intruded trap sheet. Its length in New Jersey is 

about half a mile, and it extends across the river into Pennsylvania for 

about two miles, appearing to end in either direction by thinning out. 

Its course is somewhat oblique to the strike of the inclosing strata, but it 

does not appear to have caused any considerable amount of disturbance
DARTON.] BROOKVILLE AND BLACKWELL'S MILLS TRAPS. 69

or alteration. The rock is coarse grained, and similar to that of Bald 

Pate, and its relations to the other trap masses in this vicinity are 

shown in PI. VI, p. 60, and Fig. 38, p. 61.

BrooTcville. Midway between Lambertville and Stockton there is a 

trap outcrop rising abruptly from the Delaware and extending six or 

seven hundred yards along the river, and thence northeastwardly for a 

mile and a half. It is an irregular sheet of coarse grained diabase", and 

has caused considerable disturbance and alteration in the associated 

strata. It lies very near the great fault which brings up Cambrian and 

Ordovician rocks in the center of the formation in Pennsylvania, and it 

was Lewis's opinion that the trap had been intruded in the fault rock 

of this great dislocation. Exposures are few and unsatisfactory in its 

vicinity, and the relations are not entirely determinable, but it seems 

probable to the writer that the fault passes just northwest of the trap 

which appears to be entirely inclosed in Newark shale. The trap does 

not cross the river into Pennsylvania, at least on the surface, and may 

be cut off by the fault which crosses its course at the Delaware.

SMALL DIKES.

Besides the offshoots descending from the base of the palisade trap, 

several dikes were incidentally discovered in the progress of the work, 

and Cook1 calls attention to the Blackwell's mills' dike.

BlackweWs mills. On the east bank of the Millstone Eiver, near this 

place, two miles above Millstone, there is a tine, cross-section exposure 

of a dike which was found to extend four miles westward, and Cook has 

traced it in the opposite direction nearly to the Earitan, along the course 

shown on PI. I. The dike does not appear to mark a line of dislocation, 

but extends nearly parallel to the strike of the region and has not caused 

any considerable amount of alteration or disturbance. The following 

section shows the relations in the Millstone Eiver exposure:

FIG. 47. Trap dike in bank of canal 2 miles south of East Milletone, New Jersey, looking northeast.

The trap is a fine grained, dark colored rock, with a slight tendency 

to bedded structure parallel to the walls, and the adjacent shales are

J Geology of New Jersey, page 204.
70 TRAPS OF THE NEW JERSEY REGION. IBU.LL. 67.

darkened and altered in blotckings of black, brown gray, dark red, and 

dull green.

Hackensack. About a mile east of Hackensack, on the road to Leoma, there is a small exposure of trap the exact relations of which 

could not be definitely determined on account of the drift and debris. 

It is on the crest of the first ridge east of the Hackensack Eiver, in 

west-dipping red shales, which are somewhat hardened and darkened 

in its immediate vicinity. The exposure is about ten feet in width, 

and could only be traced for a short distance along a north by east 

course. The exact line of its contact with the shales is not exposed, 

and it may constitute either an irregular sheet three or four feet in 

thickness or a dike, as suggested in the following figure:

FIG. 49. Trap dike in shales near 

South Branch, New Jersey. Looking east.

FIG. 48. Trap sheet or dike two miles east of Hackensack, New 

Jersey. Looking north.

South Branch. Five miles southwest of Somerville, on the road from 

South Branch to Neshanic, and a half mile south of the former place, 

a small trap dike is inconspicuously exposed. Its thickness is about a 

foot, and its relations are shown in the following figure:

The rock is a fine grained basalt, greatly 

decomposed at the outcrop, and although 

the associated shales are not appreciably 

altered, those on the northern or upper 

side are bent upward, as shown in the figure. The strata in the vicinity dip N. 10° 

E. > 10°, and the dike appears to trend 

northeast and southwest. 

Three Bridges. About four miles northeast of Flemington, and a 

half mile northeast of Three Bridges station, there is a small trap outcrop on the road to Centreville. Its extent appears to be inconsiderable, and its relations to the shales could not be determined. It has 

caused considerable alteration in the adjacent strata, but has not disturbed their gently northern dip. The trap is a fine grained, dark bluegray rock, similar to the other dike rocks of the formation.

Stanton station. Midway between Clinton and Flemington, one mile 

due west of Stanton station, there is a small trap outcrop in the road 

but its relations and extent are unknown.

SUMMARY.

In their genetic relations, the traps of the New Jersey region belong 

to two classes; first, the extrusive sheets contemporaneous with the 

inclosing strata and typified by the great lava flows constituting the
BARTON.] SUMMARY. 71

Watchung Mountains ; and, second, intrusive sheets and dikes, which 

attained their present positions subsequent to the deposition of the 

formation and of which the Palisade trap is a typical example.

The extrusive sheets are characterized by their perfect conformity to 

the underlying strata, the deep vesicularity and alteration, or slag-like 

aspect of their upper surfaces, the unaltered and undisturbed condition 

of the inclosing strata, the presence of trap breccias at the contacts, 

the altered and frequently vesicular condition of the rock at their bases, 

the evidence of successive flows, their relations to anterior tuff deposits, 

and their distinctive columnar structure and petrography.

The intrusive sheets are characterized by irregular lower contacts in 

which the trap cuts across the ragged edges of the strata for greater or 

less distances, the intense alteration in the inclosing strata, the increased density and fineness of grain and the bedded structure in the 

trap near the contacts, and the absence of vesicularity and breccias.

In the Watchuug Mountains, erosion, glaciation, and drift cover cause 

scarcity of outcrops of the original upper surfaces, but there are many 

localities scattered along their course in which deeply vesicular trap is 

exposed, and others in which unaltered and undisturbed strata outcrop 

very near the contact. The only actual overlap well exposed is in the 

ravine at Feltville, where the trap surface is in greater part vesicular 

and slag-like and the soft, red argillaceous shales fill the irregularities 

excepting at one point, where there is an intervening trap breccia filling 

the interstices in an " Aa"-like portion of the surface.

Contacts of the Watchung traps with underlying strata are exposed 

at intervals along the outer sides of the ridges and absolute conformity 

prevails throughout. The trap is frequently vesicular and altered and 

lies on the unaltered or very slightly altered strata along a straight or 

gently sinuous line, in one case with a trap breccia intervening.

At two points in its course the second Watchung trap is exposed, 

overlying beds of loose, eruptive materials, apparently scoria and tuff, 

and at other localities the sheet is seen to be composed of successive 

flows, the base of one lying on the vesicular surface of a preceding flow, 

in one case with an intervening layer of trap breccia at some points.

In thickness the first Watchung trap varies from 450 to 650 feet; the 

second from 600 to 850 feet; and the third from 225 to 350 feet in the 

main, and the area inclosed by the outermost hooks is about 500 square 

miles, no doubt in greater part underlain by trap, so that the Watchuug 

sheets represent lava-flows of no mean volume. Apparently the extrusions were continuous throughout, for, excepting the intercalated 

breccia above alluded to, no intervening or overlapping sedimentary 

materials were discovered. The absence of fragmental volcanic deposits, excepting the local beds at the base of the second Watchung 

sheet, is a noteworthy feature, and the first extrusions were not attended 

by ejections of scoria, ash, etc., or at most in sufficient amount to extend to the present lines of the outcrop. The eruptions which gave
72 TEAPS OF THE NEW JERSEY REGION. [BULL.67.

rise to the Watchung traps were no doubt very similar to those of some 

of the great lava-flows 01 the western part of the United States, which 

appear to have welled forth from long fissures without attendant craters or the ejection of fragmental materials.

The great hooks characterizing .the southernmost outcrops of the 

Watchung traps are entirely due to flexure, and the bowed course of 

their northern terminations aud of Towakhow Mountain are due to 

the same cause.

In the vicinity of Paterson the first Watchung trap lies on conglomeratic members, apparently representing the base of the formation, sep-° 

arated from the younger members eastward by a great fault amounting 

to at least 2,000 feet. It would appear from this that the formation 

thickens southward, for, at the southern hook the trap lies on a thickness of at least 1,500 feet of fine grained strata of which the lowermost 

members must be some distance above basal beds.

The New Vernon trap, across the Great Marsh from the Watchung 

Mountains, is apparently an extension of one of the Watchung flows 

brought up by the partial quaquaversal which determines its crescentic 

course, and it is similar to them in every respect, but not so well exposed 

for study, while the New Germantown traps farther southwestward, 

but at the same horizon, are undoubtedly extrusive and may be remnants of another extension of the Watchung flows.

The palisade trap is the best exposed instance of intrusion on a large 

scale in New Jersey, and although it is in greater part an essentially conformable sheet throughout, the supply dike from which the sheet extends 

eastward up the dip, reaches the surface northwest of Hoboken and in 

Eockland County, New York, along the inner side of the ridge.

For many miles along the Hudson River the palisade sheet is exposed 

in contact with the underlying strata near the base of the formation, and 

while the relations are essentially conformable throughout, local irregularities are frequent in which the ragged edges of the strata are crossed 

laterally up or down for over 150 feet in one instance, and trap offshoots are sent down or out into the underlying beds. In the vicinity 

of Haverstraw the crescentic course of the dike causes a corresponding 

deflection of the line of outcrop, and although this is greatly aided by the 

structure of the underlying beds and possibly by faults, the base of the 

sheet has to cross the strata for several hundred feet in order to preserve its position above the surface, and at its terminal outcrop, an 

occurrence of vesicular rock, suggests that the sheet was finally extruded.

At its contacts with inclosing strata the palisade trap becomes fine 

grained, very dense, and bedded in structure, and the sedimentary 

rocks are darkened and hardened often to a considerable distance.

A short distance west of the palisade trap, near the latitude of the 

 city of New York, are the posterior trap masses of Granton and Snake
DARTON.] SUMMARY. 73

Hills, similar structurally to the palisade trap in consisting of a dike,. 

and a sheet extending eastward up the dip.

While it seems probable that the palisade trap continues southward 

to reappear in the series of outcrops which extend from Lawrence Brook 

through Eocky Hill and Pennington Mountain to Bald Pate and Jericho 

Hill on the Delaware, it is possible that it is due to an entirely separate 

intrusion. The trap of this series of outcrops from Lawrence Brook to 

Jericho Hill is similar to the palisade sheet structurally and petrographically, and is apparently a continuous mass not reaching the surface in 

the gaps that isolate Pennington Mountain. It is heavily flanked with 

indurated shales and crosses the strike of the inclosing strata, both at 

intervals in its westerly course and in the hooked outcrop of Ten Mile 

Run Mountain.

Sourland Mountain consists of a thick sheet of coarse grained diabase, heavily flanked by highly indurated shales, and follows the strike 

of the inclosing strata excepting in a local bowing near the center of its 

course where it crosses and recrosses the strike for a short distance.

Cushetunk and Round Mountains are the remnants of a wide, thick, 

intrusive sheet considerably flexed, and eroded through at the anticlinals 

so as to give the singular horseshoe-shaped course to Cushetunk Mountain and isolation to Round Mountain. The indurated strata associated 

with this trap are crossed by it at some points, and along the western 

border for a short distance the edge of the sheet overlaps the lower 

Paleozoic limestones and presents some evidence of having been extrusive.

The smaller trap masses along the Delaware, at Belle Mountain, 

Brookville, and Point Pleasant are all local intrusive sheets intercalated 

between highly altered strata, and near Neshanic, Martin's Dock, and 

Arlington are other intrusive sheets, finely exposed in cross-section. 

The other trap masses in the New Jersey region are some small sheets 

and dikes near and northeast of Flemington, the dike so finely exposed 

near Blackwell's Mills, the dike near Hackensack, and the sheets south 

of New Brunswick.

The ages of the intrusive sheets of the formation are difficult to 

estimate. Davis has called attention to the raggedness of some of the 

contacts as evidence that the intrusion was effected before the development of joints by the uplift of the formation, and this certainly seems 

very probable.

As the stratigraphy of the Jura-Trias of the New Jersey region is 

not worked out, the horizons of the trap masses are not known, and 

the sequence of their intrusion is indeterminable from any evidence now 

in hand. The palisade trap lies just above the basal arkose, which is 

known to overlap the crystalline rocks in wells in Jersey City, and as 

the first Watchung trap lies on basal beds near Paterson, it might be 

suggested that the two sheets are not far distant in horizon, but in the
74 TRAPS OF THE NEW JERSEY REGION [BULL.67

absence of definite knowledge of the comparative age of the basal rocks 

at Paterson, and the structure and configuration of the buried Newark 

shores in the intervening region, the relative positions of the two sheets 

can only be conjectured.

At Lawrence brook the supposed southward continuation of the palisade trap is not far above the base of the formation, but in Ten Mile 

Run Mountain and Eocky Hill the strata are crossed so that at the 

Delaware the sheet is apparently 10,000 feeb above the Trenton gneisses, 

but probably there are intervening faults which might decrease this 

estimate very greatly.

Sourland Mountain trap is apparently high in the formation but its 

exact or relative horizon can not be determined until the stratigraphy 

and structure of the region cau be worked out, and the same is the case 

with the other traps of the Delaware region, and the Oushetunk and 

the Arlington traps.

BIBLIOGRAPHY.

(The following references are solely to papers or parts of papers relating to the 

traps of the New Jersey region:)

AKERLY, SAMUEL. An essay on the geology of the Hudson River and the adjacent regions. New York, 1820, pp. 69, pi. 12°.

Gives a general sketch of the extent and salient features of palisade rocks, pp. 

27-34, and a section along the Hudson River, showing the relations of the underlying strata at some points. Refers to the occurrence of amygdular rock and 

"rocks resembling volcanic scoria," near the falls of the Passaio. Discusses the 

nature of the Palisade and Newark Mountains, and seems inclined to consider 

them volcanic, pp. 62-64.

BRITTON, NATHANIEL L. On the geology of Richmond County, New York. Annals 

New York Acad. Sci., vol. 2, 1881, pp. 161-182, 2 pis.

Describes the outcrops of the trap, p. 169, and shows its extent on the map, 

plate 15.

COOK, GEORGE H. Geology of New Jersey. 1868, pp. 176-194,195, 200, 201. 202-205, 

207, 215-218, 230, 231, 337,676-679.

Principally devoted to a detailed description of boundaries, the position of contact lines, and'topography, pp. 176-194. Calls attention to the cause of the peculiar topography of Sourland Mountain, pp. 191, 192; the anticlinal structure 

in Round Valley, p. 193 ; bedded structure in trap at Martin's Dock, Belleville, 

and near Plainfleld; columnar structure in Morris Hill, Paterson, and elsewhere, 

and trap dikes at Blackwell's Mills, Flemington, and near New Brunswick. 

Gives a cross-section of the palisade trap, p. 200, and discusses the mode of its 

intrusion. Gives list of joints in Bergen Hill, pp. 202-205. Describes and gives 

analyses of some of the traps of each the principal trap masses, pp. 215-218. 

Discusses the genesis of the traps and their relative ages, p. 337. In describing 

copper ores of the formation, pp. 676-679, refers to trap at the Schuylermine and 

the exposures of base of first Watchung trap in mines near Plainneld and Somerville. On the accompanying map the trap boundaries are shown and cross-sections given across the formation.

 Geological survey of New Jersey. Annual report of the State geologist for 

the year 1874, pp. 56,57.

Announces discoveries of grains of metallic iron in trap of Bergen Hill.
DARTON.I BIBLIOGRAPHY. 75

COOK, GEORGE H. Geological survey of New Jersey. Annual report of the State 

geologist for the year 1879, pp. 20, 3^, 34.

Includes a general statement of the distinctive features of the trap outcrops 

Calls attention to an exceptional instance in which curved outcrop is not due 

to flexure in the great hook of the Palisade Mountains in New York, " where 

the trap has broken directly across the beds of stratified sandstone," p. 32. Considers all the traps intrusive.

 Geological survey of New Jersey. Annual report of the state geologist for the 

year 1881, map in pocket. Shows the trap boundaries.

Geological survey of New Jersey. Annual report of the State geologist for

the year 1882, pp. 19,22,23,31,32,43-66, map in pocket. The descriptions of the 

traps in this report, covering 23 pages, consist mainly of brief references to the 

more general features of the outcrops, their extent, topography, rocks, columnar 

structure, nature of the exposures, and the alteration and some of the relations 

of the associated sedimentary members, but in some cases the structural relations 

are briefly considered as follows:

Palisade trap. Description and ph'oto-lithograph of relations at Weehawken.

Notes overlying strata at Homestead station and Alpine, the frequency of lower

contacts, the occurrence of sandstone between trap outcrops at Bayonne City

- and in Bergen cut, and estimates the maximum thickness of the trap at 400 feet

at Alpine and 200 feet at Weehawken.

Snake Hills. Notes occurrence and dips of adjoining shale outcrops, and considers it probable that the trap has broken across the strata.

Watchung Mountains. Discusses connection with traps of Ramapo Valley. 

Calls attention to the parallelism of outcrops to strike; some of the relations of 

underlying strata at Paterson, Plainfield, and Somerville; the elevation of contact 

line in outer side of First Watchung Mountain; overlying rocks near Warrenville; the shale fragments near Mount Horeb, in the Second Watchung Mountain, 

indicating the possibility of an interval between the two sheets of trap rock 

lower contacts and columns near Little Falls, and the occurrence of cellular 

rock surface in some places along western slopes on the ridges.

Pompton, Preakness, and Hook Mountains, Biker's Bill and Long Hill. Calls 

attention to some relations of underlying strata near Pompton, in Hook Mountain and Long Hill, occurrence of cellular rock on back of the ridge near Mountain View and outliers of trap west of Pompton Plains. Estimates the thickness 

of the trap near Vreeland's quarry as at least 300 feet. Discusses cause of the 

east and west ridge of Hook Mountain, and considers it due to " a series of offsetting northeast and southwest dykes connected by outflows through fractures 

across the strata."

Basking Ridge trap. Calls-attention to the uncertainty of its boundaries and 

to the occurrence of an outlier near Bernardsville, naving cellular rock on its 

eastern slope.

New Vernon trap. Refers to outcrops of cellular rock on its surface at some 

points, and is of the opinion that the trap has broken across the strata through 

part of its course.

Martin's Dock trap. Description and photolithograph of the outcrop and references to the trap exposed south of New Brunswick. Calls attention to belt of 

indurated shales crossing the Raritan below Martin's Dock.

Ten.Mile Run. Rocky Hill trap. Calls attention to the unconformity of intrusion indicated by the curved course of these outcrops.

Sourland Mountain. Refers to some structural features and the alteration in 

the strata along its flanks.

Point Pleasant trap. Discusses its extent underground and states opinion that 

there are two sheets.

Cushetunk Mountain. Considers trap unconformabie to strata at some points, 

and to have been intruded along axial lines.
76 TRAPS OF THE NEW JEESEY EEGION. [BULL. 67.

COOK, GEORGE H. Continued.

New Germantoivn trap. Considers trap unconformable at some points. 

The trap boundaries on the map only differ from those on the map issued with 

the preceding report in having the New Vernon outcrops continuous.

 Geological survey of New Jersey. Annual report of the State geologist for 

the year 1883, frontispiece, pp. 22-25, 164-166.

Reviews Davis's conclusions in regard to the extrusive nature of the Watchung 

traps and states his opinion that, all the traps of the New Jersey region " were 

intruded after the sedimentary rocks had been elevated to their present inclined 

position.'' Describes a lower contact of the second Watchung sheet at Haledon 

and gives a photolithograph of the exposure. Calls att ention to altered strata 

associated with the Lawrence Brook, Ten Mile Run, Sourland Mountain, Palisade 

and Schuylev Mine traps as noted in the report for 1882, and on the back of First 

Watchung Mountain near Pluckamin, Feltville, andWarrenville. Does not consider the occurrence of cellular trap a decisive proof of extrusion and thinks the 

curved courses of the traps indicative of intrusion.

 Geological survey of New Jersey. Annual report of the State geologist for 

'the year 1884, frontispiece, pp. 23-28.

Description and photolithographs of the columnar trap near Orange. States 

opinion that the trap is intrusive and suggests the possibility that the small-columned rock represents the edge of a separate sheet. Calls attention to the occurrence of cellular trap on the back of the First Watchung Mountain at the Orange 

water-works.

 Geological survey of New Jersey. Annual report of the State geologist for 

the year 1885, p. 122.

Refers to a well 297 feet deep in the palisade trap in Union, and one near Montclair through the first Watchung trap into the underlying sandstones.

Geological survey of New Jersey. Annual report of the State geologist for

the year 1886, pp. 125-127.

Discusses briefly the nature of the traps and states his opinion that all are intrusive, excepting perhaps, locally, where they may have reached the surface and 

overflowed.

 and SMOCK, JOHN C. Geological survey of New Jersey. Map of northern 

New Jersey, 1874.

Shows the trap areas of northern New Jersey and Rockland County, New York, 

and gives a cross-section from Jersey City to Morristown, showing the structural 

relations of the Palisade and Watchung traps.

COOPER, T. On volcanoes and volcanic substances, with a particular reference to the 

origin of the rocks of the floetz trap formation. Am. Jour. Sci., vol. 4,1822, pp. 

205-243.

Describes thejoccurrence of columnar and amygdular " basalt" at the falls of 

the Passaic and is of the opinion that it was poured out over "the old red sandstone" and similar in nature and origin to the other traps of the New Jersey 

region.

COZZENS, ISSACHAR, Jr. A geological history of Manhattan or New York Island, 

New York, 1843, pp. 114, pi. 9, 8°.

Gives a section along the Hudson from Jersey City to Weehawken, showing 

the position of the Palisade trap and underlying strata, plates 2, 3, and a section 

at Pompton across the third Watchung trap, pi. 8. Refers to the Palisade and 

Watchung traps as unconformable volcanic rocks, p. Ill, and describes the 

columnar structure and extent of the former, p. 48.

CREDNER, HERMANN. Geognostische skizze der Umgegend von New York, Zeitschr. 

Deutsch. geol. Gesell., vol. 17, 1865, pp. 388-398, pi. 13.

Describes some of the more obvious features of the Palisade, Staten Island and 

Snake Hill trap outcrops. Considers palisade trap intrusive and the Snake Hills

due to offshoots from the main trap mass,
DAUTON.] BIBLIOGRAPHY. 77

DARTON NELSON H. On the disintegrating sandstones of New Durham, New Jersey. Trans. New York Acad. Soi., vol. 2, 1883, pp. 117-119.

Describes the relations and lithology of the strata lying against the back of the 

dike of the palisade trap in the cut at the west end of the West Shore Railroad 

tunnel at Weehawken.

DAVIS, WILLIAM MOBRIS. Brief notice of tbser rations on the Triassic trap rocks of 

Massachusetts, Connecticut, and New Jersey. Am. Jour. Sci., 3d series, vol.24, 

1882, pp. 345-349.

Refers to the palisade trap as undoubtedly intrusive and the trap of the Watch - 

ung Mountains as probably extrusive. Calls attention to the breaking of the 

dikes and intruded sheets across the strata without relation to the present joint 

planes as evidence indicating that the intrusion was effected before the formation 

was tilted.

 The structural value of the trap ridges of Connecticut Valley. Proc. Boston 

Soc. Nat. Hist., vol. 22, 1882, pp. 116-124.

Refers to some general features of the trap ridges, and instances the palisade 

trap as a typical intrusive sheet.

On the relations of the Triassic traps and sandstones of the eastern United

States. Bull. Mus. Comp. Zool., Harvard College, vol. 7, No. 9,1883, pp.249-309, 

pi. 9-11.

Besides a general review of former opinions on the subject, describes a series of 

typical localities in New Jersey, pp. 269-279, and discusses the evidence indicative of the intrusive origin of the trap of the Palisade, Sourland Mountains, Martin's Dock, Point Pleasant, etc., pp. 244-295, 296, 301, and the extrusive nature of 

the Watchung traps, pp. 291, 294, 300, 302.

Palisade trap. Describes upper contact near Englewood, lower contact at 

Fort Lee, and the unconformity and indurated shales at Weehawkeii. Suggests 

that King's Point and the occurrence of sandstones in the Bergen Cut are due to 

faulting.

Watchung traps. Describes lower contact at Patersou, faults in Garret Rock, 

amygdular and ropy trap surface southwest of Paterson, lower contacts and tuff 

deposits at Little Falls, and the surface of the first Watchung trap in contact 

with overlying unaltered shales and breccia at the Feltville locality, indicating 

the extrusive nature of the sheet. Suggests that irregularities in columnar 

structure of First Mountain maybe due to successive flows, p. 300.

Martin's Dock. Detailed description.

Point Pleasant Station. Describes main trap mass south of the station, and six 

others in the shales northward. 

EMMONS, EBENEZER. Agriculture of New York, vol. 1, 1846, p. 200, map.

Gives a section of the Palisades near the State line, and states that the intrusive nature of the trap is indicated by the .manner in which it is intercalated in 

the sandstone layers and by the alteration that ib has produced. 

GRATACAP, Louis P. Fish remains and tracks in the Triassic rocks at Weehawken, 

 New Jersey. Am. Naturalist, vol. 20,1886, pp. 243-246, pi. 12,13.

Describes strata underlying the palisade trap at the locality, and gives a section showing the position of the contact line in the entrance of the West Shore 

Railroad tunnel.

HAWES, GEORGE W. On the rnineralogical composition of the normal mesozoic 

diabase upon the Atlantic border. 1881. Proc. U. S.Nat. Mus., vol. 1, 1881, pp. 

129-134.

Gives as results of a inineralogic analysis of trap from Bergen Hill, p. 131. 

HEILPRIN, ANGELS. On a remarkable exposure of columnar trap near Orange, New 

Jersey, 1885, Proc. Phila. Acad. Sci., 1884, pp. 318-320, pi. 8.

Gives a description and sketch of the columns and discusses columnar structure.
78 TRAPS OF THE NEW JERSEY REGION. IBULL. 67.

IDDINGS, JOSEPH P. The columnar structure in the igneous rock on Orange Mountains, New Jersey. Am. Jour. Sci., 3d series, vol. 31,1886, pp. 321-331, pi. 9.

Describes and figures the columns and discusses the origin and nature of columnar structure. Shows that the Tariations in structure are not indicative of 

successive sheets and gives an account of the petrography of the rock, the glassy 

nature and disposition of the columns of which are thought to indicate a surface 

flow and not an intrusion.

KITCHELL, WILLIAM. Second annual report of the Geological Survey of New Jersey, 

1856, p. 145.

Calls attention to the occurrence of trap near Jacksonville, along the highland 

border.

LEWIS, H. CARVILL. A great trap dike across southeastern Pennsylvania. Proc. Am. 

Phil. Soc., vol. 22,1885, pp. 438-456, map.

Describes the extension of the Bald Pate, Belle Mountain, Sourland Mountain, 

and Point Pleasant traps into Pennsylvania, and some of the relations of the 

Brookville trap and the great medial fault in New Jersey.

MATHER, WILLIAM W. Geology of New York, First Geological District, 1843, pp. 

278-283,627, pis. 1,5,34,45.

Describes the palisade trap in Rockland County and Staten Island,some of the 

irregularities of lower contact along the Hudson River south of Haverstraw, and 

the alterations of the underlying strata, pp. 278-282. Considers the trap an ancient lava, "that has flowed through the rocky fissures in dikes, while this portion of the continent was still beneath the waters of the ocean," and similar in 

origin and relations to the other traps of the New Jersey region, p. 283. It is 

thought that the trap was " probably erupted at the epoch of the marl and green 

sand deposits of New Jersey," p. 627.

PIERCB, JAMES. Account of the geology, mineralogy, scenery, etc., of the secondary 

region of New York, New Jersey, and the adjacent States, 1820. Am. Jour. Sci., 

vol. 2, pp. 181-199.

Describes the general features of the more prominent trap masses of the New 

Jersey region, especially the Palisade and Newark Mountains.

ROGERS, HENRY D. Report on the geological survey of the State of New Jersey, 

1836, pp. 188, pi., 8°, Philadelphia.

All the information in regard to. the traps in this report is republished with additions in the report for 1840, excepting a plate of sections showing the supposed 

relations of the larger trap masses.

 ' Description of the geology of the State of New Jersey, being a final report; 

Philadelphia. 1840, pp. 301, map, pi., 8°.

Briefly describes the course, topography, and rocks of theprincipal trap masses 

of New Jersey, the altered strata at Lambertville, New Hope, The Swamp, Lawrence Brook, on back of First Watchung Mountain northwest of Plainfield (at 

Feltville), Rocky Hill, Moore's Creek, Sourland Mountain, and Point Pleasant, 

and the contacts at Paterson, Little Falls, and the copper mines near Somerville. 

Discusses the relations of the traps to the sedimentary members, the date and 

mode of extrusion, induration, and the origin of the copper ores, pp. 114-171, map, 

plate.

RUSSELL, ISRAEL C. On the intrusive nature of the Triassic trap sheets of New Jersey. 

Am. Jour. Sci., 3d series, vol. 15, 1878, pp. 277-280.

Refers to alteration of strata underlying the palisade trap at Paterson and 

near Plainfield, and describes a locality near Feltville where the bossy, vesicular 

surface of the first Watchung trap is exposed, overlain by highly altered shales 

and a thin bed of metamorphosed limestone. Calls attention to the occurrence 

of the trap breccia and suggests that it may " have a history somewhat similar 

to that of the 'friction breccias' mentioned by Van Cotta," considers the curved 

courses of some of the New Jersey traps indicative of unconformable intrusion.
BARTON. J BIBLIOGRAPHY. . 79

RUSSELL, ISRAEL C. On the occurrence of a solid hydrocarbon in the eruptive rocks 

of New Jersey. Am. Jour. Sci., 3d series, vol. 16, 1878, pp. 112-114.

Describes the albertite-like substance occurring in elongated vesicles, in the 

trap at the locality described in the preceding paper, and discusses its origin.

 The physical history of the Triassic formation of New Jersey and the Connecticut Valley. Annals, New York Acad. Sci., vol. 1,1878, pp. 220-254.

Includes some general statements in regard to the relations and nature of the 

traps and a discussion of their supposed former connection with those of the Connecticut Valley region.

 - The geology of Hudson County, N. J. Annals, New York Acad. Sci., vol. 2t 

.1880, pp. 27-80, pi. 2.

Describes contacts and their irregularities at the base of the palisade trap along 

the Hudson from Jersey City to Bull's Ferry, the dike at Guttenberg and some of 

the relation at Snake Hill. Gives an ideal section of the palisade trap and its 

supposed offshoots, to which Snake Hills, Fairmount, King's Point sheet, and the 

posterior ridge of Bergen Hill are thought to be due. Alludes to occurrence of 

trap at the Schuyler mine, and describes the fault rock and its supposed metamorphism in the cut west of Arlington.

 Oil the former extent of the Triassic formation of the Atlantic States. Am.

Naturalist, vol. 14, 1880, pp. 703-712.

Includes general statements in regard to the palisade and Watchung traps and 

allusions to the evidence of their intrusive nature. Calls attention to altered 

strata on top of First Watchung Mountain along Johnson's drive near Plainfield, 

New Jersey.

WURTZ, HENRY. Progress of an investigation of the structure and lithology of the 

Hudson River palisades. Proc. New York Lyceum, vol. 1, 1871, pp. 99-105.

Advances the hypothesis that the palisade trap is a metamorphic rock throughout, and appears to consider the other traps of similar nature, excepting that of 

the First Newark Mountain, which it is suggested may be eruptive in part. 

Considers the highly altered strata underlying the palisade trap transition beds." 

Describes the petrography of the trap of Bergen Hill.

INDEX.

Page. 

Akerly,S.,cited ........................... 14,74

Allentown ...... ....................... 64

Alpine..................................... 51,75

Arlington............................. 56, 57,58, 79

Awiehawken Creek ....................... 43

Basking Ridge............................. 34

Bayonne City............................42,53, 75

Belleville .................................. 57,74

Bergen Point ............................38,42,53

Bernardsville... ...................20,24,28,75

BlackweH'8Mills ........................69,73,74

Blauveltville............................... 40

BoundBrook .............................. 28

Britton, N.L., cited........................ 74

Brookville...............................69, 73,78

Bull'sFerry ............................... 79

Byram...^.................................. 68

Chimney Rock............................. 23,29

Clinton ..............'...................... 15

Cloater................................... i.. 51

Cook, G. H., cited ..... 13,14,16,17,23,25,26,33,42,

47, 58, 60,65,66,68, 74, 75,76 

Cooper, T., cited .................. ..... 14,76

Copper-Hill................................ 67

Cozzens,I., cited........................... 76

Credner, H.,cited........................14,56,76

Cross, W., cited............................ 15

Barton, N.H............................... 77

Davis, W. M., cited ..........14,15,23,25,26,28,31

42, 43,47,52, 65, 68,76,77 

Diller, J. S., cited........................... 15,26

Emmons, E., cited.......................... 14,77

Englewood................................. 77

Fairmonnt..... ....................42,43,53,79

Feltville...............14,15,26,27,28,71, 76,77,78

Flemington...........................66,67,73, 74

Floraville.................................. 62,77

Fort Lee..............................38,47,52,77

Garret Rock..........................22,23,42,43

GoffleCreek ............................... 17

Granton ...........................39,52,54,55,72

Gratacap, L. P., cited....................... 77

Great Marsh............................... 34,35

Great Notch............................... 17,23

Gutlenberg..............................43,47,79

Hackensack .............................54,70, 73

Haledon................................... 31,32

Hastings................................... 38

Haverstraw ........ 37,39,40,41,45,49,50,51,72,78

Hawes, G. W., cited........................ 77

Heilprin, A., cited.......................... 77

High Tome...............................38,44,50

Hoboken................................... 44,45

Homestead ................................ 52,75

Hopewell .................................. 60

Hudson River...............37,39,40,41,43,45,46,

48, 49, 54, 74, 76, 78, 79 

Iddings, J,P., cited........................ 23,78

Jacksonville............................... 78

Jersey City............ 38,42,43,53,54,73,75, 76,79

Kill vonKull.............................. 38,53

King's Point.............. 39,42,43,46,47,48, 77, 79

Ladentown .......__................40,41,45,50

Lambertville.-........................61,62,68,78

Lamington....................:............ 35

Lawrence Brook........................... 39

Lebanon............. ................... 63,65

Leonia..................................... 52

Lewis, H.C., cited ....................61,68,69, 78

Little Falls............... 14,20, 22,24,25, 31, 75,78

Llewellyn Park............................ 24

Long Clove..............................41.44,50

Martin's Dock...................-.39, 65, 66, 75, 77

Martinsville............................... 28

Mather, W. "W.. cited........ ............ 78

MiUington................................. 34

Millington River..... ................... 59

Montclair.......................... 18,22,24,28,76

Mount Ivy........................... ..... 40,50

Mountain View ......._..._............ 75

Munsey.................................... 40

Neshanic..............................61, 62, 67, 73

New Brunswick...................16,39,65, 66, 76

NewCity .................................. 40

New Durham........................'.37,45, 52, 77

New Germantown............ 16,17,36,36,63, 72,76

New Hope.................................. 78

New Vernon.......................-..35, 72, 75, 76

New York Bay............................. 37

North Rockaway Creek.................... 36

Nyack.............:...............39,40,48,50,51

"OneHundred Steps" .................... 46

Orange................18,22,23,24,28,30, 76,77,78

Paterson................................... 15,17,.

18,20,22,23,24,28,29,30,72,73,74,75,76,77,78 

Perry ville.................................. 15

Pierce, J., cited............................ 14,78

Piermont .................................. 44,48

Plainfleld....................22,27,29,74,75,78,79

Pluckamin...............................17,28, 76

Point Pleasant........................68,73,77,78

Pompton.............................. 33, 34,75,76

Pompton Lake............................. 25,21*

Potterstown ............................... 63

Princeton.................................. 60

Ramapo Valley ............................ 20,75

81
82 INDEX.

Page. 

Ringoes.................................... 61,62

Kockland County........................38,76, 78

RooklandLake........................38,40,49,50

Rocktown.................................. 62

Rocky Hill...............................59, 60, 78

Rogers, H. D., cited.......13,14,15, 31, 60, 62, 66,78

Russell, I.C., cited.........................13,14,

15, 26, 42,43,47, 56, 58, 59, 78, 7$ 

Schuyler's Mine ......................57,58,59,79

ScotchPlaina.............................. 22

Short Clove..............................41,44,50

Smith,F.M., cited......................... 15

Smock, J.C., cited.......................... 76

Snake Hills.....................55,56,72,75,76,79

Sneden's Landing.......................... 48

Somerville............................29,74,75,78

South Branch............. .............. 70

Page. 

Spring Valley.............................. 40

Stanton..................................63, 65, 70

Staten Island...................38,39,53,74,76,78

Stockton................................... 69

Stony Brook ......................... ..... 27,29

Sufferns ........'.........................39,40,53

Thiels| ................................ ..40,41,50

ThreeBridges ...... .................... 70

Union...................................... 76

Valley Cottage............................. 50

Van Winkle............................... 17

Warrenville .............................21,75,76

Weehawken ...........37,38,39,43,44,45,52,76,77

Wertsville..................i.............. 67

White House......... .....;................ 63,65

Wnrtz, K., cited........ .................. 79

100 steps ................................... 46