NYSGA 1958
Otto H. Muller
FIELD GUIDE BOOK
New York State Geological Association
30th Annual Meeting
HOST
Department of Geology
The City College
New York 31, N.Y.
Prepared
by
Authors of the Several Chapters
and
J. Kaikow, H. Muskatt, E. Votava
Edited and Compiled
Kurt E. Lowe

1: PALEOZOIC INLIER OF THE PEEKSKILL VALLEY
S. Schaffel
The City College
Trip 1-A, 1-B and 1-E

1: PALEOZOIC INLIER OF THE PEEKSKILL VALLEY

STOP 1. Poughquag quartzite
Walk right (N) on Highlands Ave. and right (E) on approach road to Bear Mt. Pkwy. (approx. 500 ft.). Outcrop of Poughquag quartzite (Cambro-Ordovician) in unconformable contact with Highlands gneiss (Pre-Cambrian). Dips of bedding and foliation are nearly vertical. This relation is considered typical of that between Paleozoic sediments and Pre-Cambrian crystallines along the south side of the Peekskill inlier.

STOP 2. Annsville phyllite
Southwest extension of Gallows Hill underlain by Annsville phyllite (Cambro-Ordovician Hudson River pelite group) and mantled by Pleistocene delta deposits. Interesting consolidation and solifluction structures have been collected at base of hill. Walk through US 9 roadcut following left (W) side of cut only. Take care to stay on the roadway. Observe prominent slaty cleavage (axial plane type), diagonal shear planes, flow folding of quartzite bands and later quartz veins.

STOP 3. Wappinger limestone
Wappinger limestone (Cambro-Ordovician) outcrops on north side of west abutment of bridge. Observe gradational contact with Annsville phyllite outcropping along steep west bank of creek. Specimens from this transition zone are identical with those from the Wappinger limestone outcrop at stop 4.

STOP 4. Critical Outcrops
Outcrops along left (W) side of road, Cambro-Ordovician sequence exposed from S to N (dipping east) Annsville phyllite (approx. 100 ft.) Wappinger limestone (10 - 15 ft. ) is dark gray, fine-granular transition facies (same as in contact zone at Stop 3) Poughquag quartzite, coarse granular (only a few inches exposed), In contact with granite pegmatite (Highlands crystallines). Is this an intrusive or unconformable contact? Pre-Cambrian Highlands gneisses outcrop intermittently from this point northward. Berkey (1919), on his geologic map of the West Point quadrangle (1) shows the northern border fault of the Peekskill inlier passing between the Annsville phyllite and the Poughquag quartzite at this point; (2) fails to indicate the presence of Wappinger limestone; (3) indicates an unconformable contact between Poughquag quartzite and the Highlands crystallines. This critical exposure does not yield clear evidence of faulting either within the sediments or between them and the crystallines. An orderly sequence of Cambro-Ordovician sediments appears to be present here lending support to the concept of the synclinal structure of the inlier (Plate 2). The much reduced thicknesses of the Poughquag and Wappinger support the interpretation of Bucher (1957) (Plate 2. Fig. B).

STOP 5. Annsville phyllite and Highlands gneiss
South side of roadcut shows Annsville phyllite and Highlands gneiss with intervening limestone flow breccia (relations are somewhat obscured by grading): Breccia appears to be tectonic and represents the continuation of highly deformed and metamorphosed marbles along Canopus Creek (to NE) called Grenville by Berkey (1919). Its stratigraphic position, however, makes its correlation with the Wappinger limestone a likely alternative. In that case, the Canopus Creek carbonate belt may be infolded and infaulted Cambro-Ordovician rather than Pre-Cambrian marble.

2: NEW YORK CITY SERIES
K. E. Lowe and S. Schaffel
The City College
Trip 2-B and 2-E

2: NEW YORK CITY SERIES

STOP 1. Fordham gneiss
Quarry behind transformer station at left (N), now used by N.Y. State for gravel and road machinery storage. Typical Fordham gneiss, the oldest formation of the New York City series.

STOP 2. New York City series
The 3 formations of the New York City series outcrop in close proximity, although actual contacts are not exposed.
Manhattan schist (garnetiferous muscovite schist) NW of the intersection along a side road;
Inwood marble (medium grained, crystalline marble, here containing accessory graphite) in road cut on both sides of Granite House Rd.
Fordham gneiss (banded biotite gneiss) a short distance SE along cut-and-cover portion of Catskill Aqueduct. Formations appear conformable with nearly vertical dips. These rocks were traced continuously from the New York City line to this locality by Fluhr (1940). The thickness of the Inwood marble here is much reduced compared with that prevailing in New York City (approx. 750 ft.), a feature which is rather common in Westchester County. It has been explained by "squeezing-out" of the highly plastic rock and by faulting.

Manhattan schist
Manhattan schist exposures for the next 3 miles.

View of Palisades
View of Palisades across the Hudson River (below crest of hill)

Palisades and Hudson Highlands
Next 0.4 miles: Good view of strongly dissected Palisades to west and Hudson Highlands escarpment to northwest

Delta and moraine
Cross Croton River; Croton Point delta and moraine at left (W)

Deltaic deposits
Croton Pt. Ave. (entrance to Croton Pt. Park) left (W); deltaic deposits at right (E).

Palisades and Hudson Highlands

Gravel pit
Remnants of a worked-out gravel and sand pit (part of Croton Point glacial delta)

Manhattan schist
Exposures of Manhattan schist along road

View of Hudson River Gorge
View of southeastern gateway of the Hudson River gorge straight ahead (N)

Cortlandt complex
Exposure of Cortlandt complex hornblende norite with spheroidal weathering having passed over contact between Cortlandt intrusive complex and the Manhattan schist a short distance back (not exposed)

Exposures of Cortlandt complex hornblende norite at right (N)

Exposure of Cortlandt complex pyroxenite at left (S)

Inwood / Manhattan contact
At left (SW) (in front of school) contact between Inwood marble and Manhattan schist

STOP 3. Verplanck Point Quarry
STOP No. 2-3: Verplanck Point Quarry (N. Y. Trap Rock Corp. )
Approach to quarry is down the flank of a large mound of tailings deeply carved by erosion into typical badland topography. Pass several large glacial erratics below (Highlands crystallines).
DO NOT walk too close to the edge of the quarry which has not been in operation for some years.
In east face of quarry (looking north) is well-exposed contact between Manhattan schist above and Inwood marble below showing interbedding. Dips are steeply to the east (into quarry face). The Inwood marble, except for its rather fine texture, appears to be typical. In the schist, biotite predominates over muscovite and the texture is fine-grained and more gneissic than schistose. The variation from the typical lithology of the Manhattan schist in New York City is attributed to the influence of the Cortlandt intrusive pluton.
Depending on the water level in the quarry (the water is approx. 150 ft. deep) evidence of isoclinal folding of the marble can be seen in the north face of the quarry.
Collapse of the top of the east quarry face recently exposed a discontinuous zone of coarse Inwood marble breccia in a greenish to reddish crystalline matrix, close to the contact with the Manhattan schist. Mr. S. Schaffel who first observed this curious rock believes that it is of tectonic origin and that the matrix was affected by gaseous or hydrothermal solutions from the Cortlandt intrusive. Angular fragments of marble appear to be quite fresh and unaltered. Detailed microscopic examination of this rock (unreported from any other Inwood marble locality) will be undertaken in the near future. This interpretation then assumes at least post-Taconic age for the Cortlandt intrusive (see discussion of age relations of the New York City series).
1.5 miles to the southwest across the Hudson River can be seen the Tomkins Cove quarry (N. Y. Trap Rock Corp. ) in Wappinger limestone (Cambro-Ordovician). As discussed under age relations of the New York City series in the preceding pages, several attempts have been made to correlate this series with the Cambro-Ordovician rocks of the Hudson valley. At this locality the Wappinger limestone and Annsville phyllite (Cambro-Ordovician) are in rather close proximity to the Inwood marble and Manhattan schist (uncertain age), with only the width of the Hudson River intervening. This feature makes the correlation of these two rock sequences a tempting possibility. Let us then review briefly the several alternative lines of reasoning:
(1) The Verplanck Point rocks could be the metamorphic equivalent of the Tomkins Cove sediments on the basis of similar composition, stratigraphy and structure. Paige (1956) suggested an anticlinal arch across the Hudson River along which the progressive kinetic metamorphism took place in an easterly direction. The same author also indicated that contact metamorphism associated with the Cortlandt intrusion could account, at least in part, for the metamorphosed nature of the rocks at Verplanck Point.
(2) The authors cannot agree with this interpretation. Contact metamorphism would require an unusually broad contact zone around the margins of the intrusive, a feature which does not seem to be present in other localities at similar distances from the intrusive contact. Also the characteristic contact emery deposits in the mica schist seem to be absent here.
Progressive metamorphism could offer a plausible explanation were it not for the remarkably short distance in which a typical phyllite is supposed to have changed to a biotite-muscovite schist. One way out of this dilemma would be the assumption of westward thrusting (under the Hudson River) to account for the present proximity of the two contrasting metamorphic terranes.
(3) Verplanck Point rocks of the New York City series could be older than the Cambro-Ordovician sediments at Tomkins Cove. In that case the two rock groups must be in unconformable contact with each other beneath the river.
It becomes evident that the clue to this problem of correlation is buried under the Hudson River whose bedrock profile and structure are not known in this locality.
Note a typical kame ridge (in cross-section) on top of the north quarry face.

STOP 4. Inwood / Manhattan contact
Contact between Inwood marble and Manhattan schist on right (S) side of road. Note bands of small cubic pyrite crystals in the marble (influence of the Cortlandt intrusive).

Manhattan schist exposures along road

Cortland complex
Start of massive, glaciated exposures of Cortlandt complex augite norite at right

Cortlandt complex exposures
Intermittent exposures of Cortlandt complex augite norite for the next 1.5 miles

Last exposures of Cortlandt complex rocks (augite norite)

3: THE CORTLANDT COMPLEX
A. Dolgoff
N.Y. City Department of Public Works
Trips 3-A, 3-B and 3E.

3: THE CORTLANDT COMPLEX

View SE gateway of Hudson Gorge
Pause: View of southeastern gateway of the Hudson gorge - on west side of River (from left to right): Dunderberg, West Mtn. and Bear Mtn. (with tower).

Hill at right with outcrops of Cortlandt complex augite norite

Norite outcrops along both sides of road

STOP 1. Olivine pyroxenite
Olivine pyroxenite near northwest margin of "Eastern Funnel" (E on Plates 4 to 8) and "Olivine Region" (Plate 6). Typical spheroidal weathering similar to that of olivine zone in the Palisades. Dickerson Hill (center of "funnel") to the southeast. Banding mapped by Balk (Plate 5) is difficult to distinguish in this exposure. Discussion of structural and petrologic features of the Cortlandt complex.

Pyroxenite
Next 0.4 miles: Outcrops of pyroxenite at right (E)
The outcrops are either on the left (E) or on the right (W).

STOP 2. Old quarry dumps
Old quarry dumps on both sides of road. Collect samples of Pyroxenite (with and without olivine) and augite norite. Note indistinct banding and quartz -pegmatite veins cutting pyroxenite and norite.

Cortlandt complex / Manhattan schist contact
Pause: Passing over contact of Cortlandt complex with Manhattan schist (country rock); schist outcrops on both sides of road.

Schist outcrops at right

STOP 3. Kingston Emery Quarry
Kingston Emery Quarry (operated by Colbate Emery Co. , Peekskill, N. Y. ) presently the only operating emery quarry in the Cortlandt complex. Note the following:
(1) In quarry, down near the working face, excellent rectangular jointing. Rocks are highly magnetic. South quarry wall shows crusts of quartz and calcite, and quartz veins in the pyroxenite.
{2} Walking up cut leading out of main excavation observe the pyroxenite grading into more banded augen schist which becomes a normal schist at the quarry entrance (Colabaugh Rd.). This zone of transition represents the Cortlandt complex - Manhattan Schist contact. The country rock shows evidence of having been mobilized by the Cortlandt pluton during intrusion. The contact effects are also well shown in the schist outcrops near the construction shacks. The quarry has only been in operation since 1942. The contact shown on Plates 4 to 8 is not quite accurate and should be shifted southwestward close to Colabaugh Pond Road.
(3) Emery ore (samples on dump at quarry entrance) is dark blue-gray with an occasional pinkish hue and massive. Quarrying operation has followed ore vein down-dip.

STOP 4. Hornblende norite
Hornblende norite with poikilitic hornblende near western margin of central "basin" (C of Plates 4 to 8). Platy structure of hornblende crystals can be observed.

Poughquag quartzite
Pause: Poughquag quartzite (Cambro-Ordovician) in unconformable contact with Highlands gneisses (Pre-Cambrian) at right (S). Dips are nearly vertical.

4: PLEISTOCENE GEOLOGY OF CROTON POINT
Cecil H. Kindle
Trips 4-B and 4E.

4: PLEISTOCENE GEOLOGY OF CROTON POINT

Former Croton River delta
If one had chanced to come along route NY-129, one would have observed the gravel and silt deposits of the former Croton River delta on the left (S) just before reaching US-9.

Former delta surface
Continuing along US-9 we rise up onto this former delta surface and find a traffic light ahead. Let us turn right (S) here on Croton Pt. Ave. and proceed to the Harmon railroad station (Fig. 1) Here we notice the wide cut made for the railroad and its shops.

Croton Point
We do not stop now, but continue, observing a former tidal swamp, now filled with rubbish, on our left. Soon the delta remnant is behind us and we travel on a tombolo (bathing beach on our right and former swamp on our left) to the outer portion of Croton Point. We proceed to the large parking field at its southern end.
Ahead of us we see a sand pit which furnishes the material used to cover the rubbish in the former swamp. Let us examine this exposure. Here we find another remnant of the old Croton delta with sand and fine gravel resting on varved silty clay. Occasional concretions may be seen in the latter. Some of the silty clay layers are disturbed with horizontal layers above them. Are they the result of slumping or disturbance by floating ice?
Let us now walk S along the shore. We see numerous bricks, castoffs from the days when bricks were manufactured here. Behind some swimming rafts parked above the reach of the tide we see a cattail (freshwater) swamp which marks the source of clay used in brick manufacture.
As we proceed beyond the swamp we see delta sands, and 100 yards or so further we observe these varved clays resting on glacial till containing boulders of various sizes in a reddish matrix. Now we realize the source of the boulders among which we have been threading our way along the beach. The surface of this moraine is uneven and appears to be dropping below sealevel for a distance before rising to 40 or 50 feet above sealevel at Teller's Point (Fig. 1). A boulder bar extending south of Teller's Point marks its further continuation.
As we return to our cars we realize the preservation of the outer remnant of the Croton delta from wave erosion must be credited to this moraine.
We can now drive to the north end of the parking area and examine the north tip of the outer part of Croton Point. The weather and the state of the tide will determine whether we walk along the outer side of the point (more boulders) or the inner side (shorter). Woodchuck holes indicate that the top of the southern end of this point is deltaic sand. At the north end are glacial till and Indian shell beds. Erosion appears to be rapid at all points along the shore. Waves have certainly cut down the size of the Indian campsite (at the point) considerably since the oyster beds were laid there. Was sealevel lower a short time ago? Does the (now buried) tidal swamp south of the tombolo indicate that sealevel was lower when that portion of the old delta was eroded?
Return to cars and drive back to headquarters following the same route as taken at the start of the trip. Compare route description of Trip 2-B between mileages 20.9. to 25.8 and 30.6 to 36.4.

C: THE GEOLOGY OF THE TRIASSIC LOWLAND OF SOUTHEASTERN NEW YORK AND NORTHERN NEW JERSEY.
George F. Adams
Trip C

C: THE GEOLOGY OF THE TRIASSIC LOWLAND OF SOUTHEASTERN NEW YORK AND NORTHERN NEW JERSEY.

Annsville phyllite
Roadcut through Gallows Hill; Annsville phyllite (Cambro-Ordovician) Hudson River pelite group; see Trip 1, Stop 1- 2).

Glacial deltas
Note remnants of glacial deltas along both valley walls

Climb Highlands escarpment
Road starts climbing Highlands escarpment (fault line scarp); continuous exposures of Highlands crystallines (Pre-Cambrian gneisses, schists and granites) from here to Bear Mt. Bridge.

STOP 1. Anthony's Nose
Anthony's Nose lookout point. The Hudson River has cut a gorge through the Pre-Cambrian crystallines below the Schooley peneplane level, here shown by the hilltops. The rock bench on which the Bear Mt. Inn is located is interpreted as a remnant of the Harrisburg peneplane level formed by the Hudson River when it meandered at this level. Since Harrisburg time uplift permitted the stream to cut to lower levels before the valley floor was drowned. Glacial modification of the valley is indicated by its fiord-like walls and the shortcut east of Iona Island. The crystallines form an upthrown block of the fault associated with the Triassic Lowland to the south. See description of Trip D, Stop 1.

Views from bridge
Excellent views crossing bridge:
Left (S): lona Island and southeastern gateway of Hudson gorge; prominent notch at Timp Pass (SW) where major thrust fault crosses Dunderberg-West Mtn. ridge crest
Ahead (W): North side of bridge: Mouth of Popolopen Creek (drowned); Hell Hole fault notch between Bear Mtn. (left) and The Torne (right); Crown Ridge extending northeastward from The Torne; all these owe their topographic prominence to the Storm King granite
Right (N): Southern portion of the Hudson gorge; Sugarloaf Hill on east shore (3 mi.) (Canada Hill granite phase); Livingstone Island (east shore, 1 mi.) and Cons Hook (west shore, 2 mi. ) are separated from the shore by abandoned channels of the Hudson; bedrock terraces, particularly prominent on west shore.

River channel
Iona Island and abandoned river channel at left (E); Doodletown Brook (subsequent stream on Timp Pass-Hudson River thrust fault) at right (W); fault crosses road at this point

White, graphitic marble (Greenville?) at right (W)

View of Hudson gorge and gateway to left (N)

Hudson River Reserve Fleet
Hudson River Reserve Fleet (ship "graveyard" of World War II) at left (E)
There were probably over 130 ships here at the time of the field trip. All were gone by 1972.

View of Verplanck Point quarry
Verplanck Point quarry (Pre-Cambrian or -early Paleozoic Inwoodmarble) across River at left (E).
2010: Also of possible interest, the nuclear reactors Indian Point #1 and #2 are just to the north of the quarry.

Tomkins Cove quarry
Tomkins Cove quarry (Cambro-Ordovician Wappinger limestone) at left (E)

Wappinger limestone outcrop at left (E)

Triassic redbeds
Cross bridge over Cedar Pond Creek; Triassic redbeds along both walls of gorge below

High Tor
Haverstraw railroad station at left (E), Palisades (High Tor) at right (W)

STOP 2. Haverstraw Quarry
level with crusher and loader at right (pick up Company guides)
Haverstraw Quarry of the N. Y. Trap Rock Corp.
Buses follow quarry road to left and take middle road (SE) at fork of roads; gentle uphill grade
Lower Quarry Level (appr. elevation 238 ft. ):
The quarry, extending in a NW - SE direction, is in the intrusive diabase forming the northern arc of the Palisades. Here the strike of the diabase body is oblique to the strike of the Trias sic sediments to the southwest indicating a cross-cutting relationship of the tabular igneous mass.
The prominent columnar structure of the diabase changes in attitude from nearly vertical (in the northeast quarry face) to easterly dips of 450 to 500 (in the northwe st and southeast quarry face s). This feature suggests a rather abrupt change in the attitude of the intrusion with re spect to the country rock from a gently dipping (150 SW) sill-like body to a steeply dipping (450 SW) dike. Prelimiary results of recent extensive diamond core drilling on the Company's property bear out this contention (Fig. 2). It is not yet known whether the sill-like portion (Upper guarry level and Little Tor) is a true sill or a low-angle dike transgressing across the equally gently dipping Triassic sediments. The true thickness of the diabase intrusion appears to be approx. 700 ft.
Farther south the upper contact of the steeply dipping diabase dike can be seen cross -cutting the Triassic sediments at the portal of the West Shore Railroad tunnel (mileage 22.7). No stop will be made at this locality.
Also observe occasional oblique shear planes with narrow zones of brecciation in the northeast quarry face. return (NW) to crusher level sharp right (SE) turn on road leading to upper quarry level; steep grade
Upper Quarry Level (appr. elevation 340 ft. ):
On a clear day, a fine view of the Triassic Lowland shows the low sandstone ridges striking toward the observer and oblique to the diabase dike. The ridge line at the back of the quarry extends southward for several miles showing the mature dissection characteristic of the Schooley peneplane remnants. In the far distance (S) the even summit area of the Palisades is characteristic of the early mature dissection of the Fall Zone peneplane remnants. Sparkill Gap near the boundary of the two surface s is hidden from view. The headwater s of the Hackensack River have been impounded to form the Lake DeFore st re servoir seen directly south. Turning toward the impressive northeast quarry face, osbserve extensive mass wasting aided by the near-vertical columnar structure and joint (.shear) planes dipping toward the quarry floor. A 50 ft. wide bench at approx. 430 ft. elevation, indicating the earlie st quarry level, has been almost buried under weathered debris. This represents one of the hazards of quarry operation, overcome in part by leaving ever wider benches on successively lower levels (thus reducing the rock volume that can be quarried).
Return (NW) to crusher level
2010: Quarry operations over more than fifty years have modified this stop considerably. This path will correspond to the road log after leaving the quarry.

Columnar jointing
Unusually well-developed, polygonal columnar structure at left (SE)

Upper contact of dike
Passing over West Shore Railroad tunnel; portal at right (S) below road shows steep upper contact of diabase dike cross-cutting the Triassic sediments.

Roadcut through Palisades diabase

Triassic Redbeds
Triassic redbeds (arkose of the Stockton formation) dipping gently NW (into cliff) at right (W) (behind bottling plant); top of outcrop approx. 150 ft. above sea level; Tappan Zee at left (E).

STOP 3. Sparkill Gap
Note: Take your belongings, because the party will not return to buses until after lunch (approx. 1.5 hrs.)
As the Gap is approached from the north along the Hudson River several outcrops of the Stockton formation (mileage 30.9) extend up the valley wall to about 150 ft. above sea level. The contact with the diabase is not visible at these localities, but must be above 150 ft. elevation.
Walk across bridge into Tallman Mt. Section of the Palisades Interstate Park. Follow shore road southward. Here the diabase is first seen extending to sea level. Although the contact is not exposed at this point, its position can be estimated from the location of the olivine zone about 30 ft. above sea level. Elsewhere this zone is known to lie about the same distance above visible contacts. It is interpreted as the result of magmatic differentiation by gravitative settling of early olivine crystals in the still fluid diabase magma. The olivine concentration in the zone is up to 25%.
Continuing along the shoreline past the swimming pool, an outcrop of arkose holds up a low terrace a few feet above sea level. A ledge at the back of the terrace is indurated arkose near the igneous contact, which is not exposed. The higher slopes expose fine -grained diabase and farther up the olivine zone.
Farther south, at a place not to be visited, the contact rises to over lOft. above sea level. It is evident, therefore, that there is a sag in the base of the sill at Sparkill Gap which may be associated with faulting. That a thickening of the diabase is not involved, is indicated by a distinct narrowing of the width of outcrop at the Gap. We now walk back up the automobile road to the level of the Gap floor (some 200 ft. above sea level). Here coarser diabase outcrops nearer the interior of the sill. We are close to the north side of the Gap which extends southward for about 2 miles before the slopes rise to the summit at 500 ft. elevation (see mileage 36.1 to 36.7). To the north, we look down on the water gap of the Sparkill. An offset of the diabase on the west side of the gap indicates that this creek follows a cross fault. It is the only stream cutting through the Palisades for its entire length from Haverstraw, N. Y. to Bayonne, N.J. On the other (N) side of the Sparkill the diabase slopes rise to rounded hills reaching heights of 700 ft. Care must be taken to distinguish between the actual water gap of the Sparkill and the interpreted earlier wind gap of broader dimensions and greater height (Plate 9, Fig. A).
Johnson (1931) interpreted the wind gap as a part of the former course of the Hudson River established as a superposed subsequent during the Schooley cycle. Later the river cut a water gap through the Palisades sill during the Harrisburg cycle. This water gap was abandoned when capture diverted the Hudson into its present course southward. At this time a reversal of drainage through the gap established the Sparkill as a tributary to the Hudson along the fault line mentioned above. (Plate 9, Fig. B).
Lunch in picnic grounds at north end of Tallman Mt. State Park return to buses via the same route

Fall Zone peneplane
Turn off road to right in front of large (burnt-out) road house Pause (if time permits): Discussion of Fall Zone peneplane level.

STOP 4. Flatrock Brook
The outcrop of diabase near the road is close to the upper contact of the Palisades sill. It is fine-grained and cut by thin acidic dikes. The hill-slope down toward the Brook approximates the dip-slope of the upper contact. The contact zone appears in the Brook as the diabase gives way to light-colored baked shales with low northwesterly dips. The actual line of contact is obscured by cover. Similar baked shales are found at the lower contact near Edgewater, N. J. but of much darker hue. The baked shales of the upper contact continue south along the strike of the sill. Their most impressive exposure is in Granton Quarry at North Bergen, N. J. where they underlie a subsidiary sill of diabase. Fossil fish (coelacanths) and a small crustacean (ostracod) have been collected from that locality. Both the lithology and fossil content of these beds strongly suggest the Locatong formation, although they occur many miles north of the main outcrop area of this formation.
Looking east from the road outcrop, one sees US-4 descending a valley which runs oblique to the upper contact in a northerly direction. The valley follows a fault line of the gravity type with downthrow on the east. The vertical displacement is approx. 100 ft. and appears to be related to adjustments connected with the emplacement of the magma.
Looking west, one sees the drowned valley of Overpeck Creek and beyond the low sandstone ridges of the Brunswick formation, approx.at the Harrisburg level. The skyline ridge is the First Watchung Mountain, a lava flow (fissure type) approximating the Schooley level. It should be possible to make out the Paterson wind gap which is similar in form and origin to the Sparkill Gap.

STOP 5. Brunswick Formation
Woodcliff Lake area - Brunswick Formation Construction of the Garden State Parkway below produced this new road and outcrop. These are rather typical sandy beds of the Brunswick formation. The shaley beds are usually found in the valleys. The brown sandstones here contain a few pebble beds which could be stream channel deposits. Conglomerate cobbles similar to those found near the border fault (Stop C-6) in alluvial fan deposits suggest a westerly source. This outcrop is about 8 miles from the border fault.

STOP 6. Triassic Border Fault
Park at right (on US-202): outcrop along road (uphill) at left (NW) The outcrop consists of badly sheared, Pre-Cambrian (granite) gneisses. Many slickensided surfaces are parallel to the surface of the border fault. The lineation (fault striae) approximates the direction of relative motion along the fault. While this is not considered to be the actual fault plane (dipping steeply southeast with downthrow of Triassic sediments to the south), it is probably within the fault zone. From a high point one sees the escarpment (Ramapo Mts. of the Hudson Highlands) extending beyond the Thruway toward the southwest. This escarpment is the product of differential erosion along the fault whose relative motion dropped the Triassic beds down on the southeast in contact with the Pre-Cambrian crystallines. The whole mass was deeply eroded by the time the Schooley peneplane was produced. The escarpment was developed later as a consequence of regional uplift. Looking southeastward toward the Triassic Lowland, a prominent hill just across the Thruway is an eroded plug-like intrusion of diabase (now being quarried for crushed rock).

Highway leaves fault line
US-202 swings away (S) from fault line proceeding on the rocks of the Triassic basin

STOP 7. Triassic Border Conglomerate
Y-intersection with Viola Rd. (Antrim Playhouse sign); park in triangular plot at right of US-202; outcrops on both sides of road These outcrops are about 1/4 mile east of fault line. Here the Mahwah River has etched a valley along the fault zone in Triassic beds. The outcrop at left (NW) side of road indicates former alluvial fan which was banked up against the original fault scarp. The presence of early Paleozoic cobbles, sometimes only slightly rounded, and the absence of the crystalline cobbles lead to several conclusions: (1) streams cutting into the upthrown block were relatively short, (2) the upthrown block was much higher than at present and contained a thick Paleozoic cover, (3) as the streams cut into this cover they nowhere reached the Pre-Cambrian basement, and (4) the upper surface of the fan must have been higher than the present Schooley level. What we see now are a few remnants of this fan showing typical torrential cross-bedding and rapid changes in grain size. Cobbles consist of Cambrian quartzite, Cambro-Ordovician limestones and Silurian-Devonian conglomerates. None of these rocks are now present on top or within the Pre-Cambrian crystallines of the Hudson Highlands directly to the northwest. Some have been preserved, however, as inliers to the west (along the New York-New Jersey border and in the New Jersey Highlands). They also outcrop abundantly in the Great Valley beyond the present Highlands to the north and northwest. On the east (SE) side of the road, pebble beds decrease and a more normal Brunswick aspect appears, similar to that seen at Stop C -5.

Fine-grained diabase
Lime Kiln Rd. at right (S); fine-grained diabase; intrusions of diabase outcropping intermittently along south (right) side of road for the next 1.5 miles are presumed to be one or more plug-like bodies or dikes; rare contact exposures show cross-cutting relationships.

Coarse border conglomerate at right (S)

Coarse border conglomerate on both sides of road

Diabase with columns
Next 0.2 miles: fine-grained diabase with columnar structure at right (S)

STOP 8. Mt. Ivy Glacial Delta
Park at entrance of sand and gravel pit at left (N) side of road This appears to be a fairly normal delta deposited in a periglacial lake, with typical top and foreset beds. No varved clays are exposed. The elevation of the delta top is 400 + ft., which indicates that it was a local lake feature not connected with the Hudson River 4 miles to the east.

View of Palisades
View of Palisades ahead to right (E); westerly end of hook-shaped Palisades ridge (dike) rising from beneath Triassic sediments (Plate 13)

STOP 9. Triassic Fanglomerate
This remarkable remnant of another alluvial fan consists almost entirely of semi-rounded Wappinger limestone (Cambro-Ordovician) pebbles poorly cemented by calcite and hematite. The source formation can be seen in place along a road to the north (mileage 86.5) and has wide exposure in the Tomkins Cove quarry 0.5 mile to the north. The occurrence of the Cortlandt complex and some gneisses of dubious age at Stony Point to the east suggest some complicated step-faulting in the region.

Wappinger Limestone
Roadcut through folded Wappinger limestone (Cambro-Ordovician); this belt of limestone widens northward where it is quarried at Tomkins Cove (0.5 mile)

D: PRE-CAMBRIAN AND PALEOZOIC GEOLOGY OF THE HUDSON HIGHLANDS
Kurt E. Lowe
Trip D

D: PRE-CAMBRIAN AND PALEOZOIC GEOLOGY OF THE HUDSON HIGHLANDS

STOP 1. Anthony's Nose
Anthony's Nose Lookout (See Plates 10 and 11, Fig. B)
Lithology: Canada Hill phase of Highlands Complex (Canada Hill granite of Berkey, 1919) - biotite oligoclase granite with epidote pods; gneissoid structure not pronounced; interpreted as granitized meta-sediments
Hudson Gorge: Southeastern gateway of Hudson gorge; superposition versus progressive headward stream erosion of the Hudson River; Iona Island and abandoned River channel; significance of bedrock terrace at Bear Mt. Inn
Faulting: Timp Pass - Hudson River thrust fault; channel fault (?) at Dunderberg ML ; Hell Hole tear fault (Popolopen Creek)
Regional Structure and Intrusive Plutons: Synclinal plutons of Storm King granite: Dunderberg and West Mts. (lower pluton) Bear Mt. - The Torne and Crown Ridge (upper pluton)

Views crossing bridge
Excellent views crossing bridge:
Left (S): Iona Island and Southeastern gateway - prominent notch at Timp Pass, where fault crosses West Mt. - Dunderberg ridge
Ahead (W): South of bridge: Bear Mt. terrace North of bridge: Mouth of Popolopen Creek (drowned); Hell Hole fault notch between Bear Mt. (left) and The Torne (right)
Right (N): Hudson gorge (southern portion); Sugarloaf Hill on E-shore (3 mi. NE) (Canada Hill granite phase); abandoned river channels at Livingston Island (1 mi. on E shore) and Cons Hook (2 mi. on W shore); bedrock terraces, particularly on W-side of river

STOP 2. Bear Mt. Inn Terrace
Walk N along W-edge of playing field: glaciated and striated outcrops of pegmatitic Canada Hill granite phase (S of roller skating rink); outcrop of sillimanite-garnet-biotite gneiss and schist (metasediments of Highlands Complex) at SE corner of rink
Hessian Lake: Shallow, glacially scoured contact line depression in Grenville (?) metasediments (including marble bands); intrusive contact with Storm King granite pluton along Sand W shores of lake; Canada ~lill granite phase along NE shore (Plate 12).
Ancient landslides of large Storm, King granite blocks (SW shore) from near vertical cliffs (obscured by trees) developed along major NE trending longitudinal joints in granite; prominent exfoliation of Storm King granite along W -shore; steep W -shore profile developed parallel to linear and platy structure of hornblende crystals in Storm King granite

STOP 3. Storm King Granite Contact
This stop on SW flank of Bear Mt, will be reached on foot (.6 mi. from entrance), because buses are not permitted on the Perkins Drive. It is regrettable that the planned visit to the top of Bear Mt. had to be eliminated for the same reason.
Keep to the left side of the Drive facing traffic and watch for cars on this winding 2-lane, 2-way road.
Layered sequence of Highlands Complex rocks: Biotite and hornblende gneisses and schists with intercalated bands of pseudo-alaskite (Canada Hill granite phase); interpreted as the result of selective granitization of metasediments (micro-pegmatite bands parallel to structure; replacement of quartz by plagioclase feldspars and perthite in thin-section); biotite in places makes rock indistinguishable from Canada Hill granite of Berkey.
Lower contact of Storm King granite pluton: (at nose of syncline) with metasediments; xenoliths near contact; dark- green, chloritized, quartz-rich contact phase of Storm King granite 500 ft. NW along road; prominent exfoliation of massive granite; typical "rubbly" weathering along linear hornblende structure; if time permits: visit to eclogite locality 100 feet below on abandoned road; metamorphic pyroxene (diallage) - garnet - graphite - quartz layer in Highlands Complex; source rock questionable.
2010: Path shown assumes users will not be in buses.

Banded metasediments
Prominently banded metasediments (biotitic and graphitic gneisses and schists) at left along Palisades Parkway.

Brooks Hollow marble
Passing between Lake TeAta. (left -S) and Lake Massawippa (right -N); construction of dam (at N end of Lake Massawippa) across the Brooks Hollow Creek temporarily uncovered a striking coarse-grained marble (contact-metamorphosed by intrusive Storm King granite) consisting of pink calcite, pale-green diopside and brownish phlogopite (named the Brooks Hollow marble).

STOP 4. Popolopen Natural Bridge
Walk 0.25 mile to SW end of Popolopen Lake
Natural Bridge across creek flowing into Popolopen Lake, developed through coarse, white, chondrodite-bearing marble; spinel dike on down-stream (lake-side) of bridge; curious dense, dark gray rock paralleling marble and creek on upstream side; thin-section study suggests a metamorphosed graywacke; both rock types along creek are completely different from known Pre-Cambrian metasediments in the Hudson Highlands; preliminary reconnaissance also indicates strong deformation of Highlands rocks along both sides of Popolopen Lake valley; rocks at this locality are, therefore, interpreted as infolded (and possibly infaulted) Paleozoic sediments(inlier).

Top of Escarpment
Top of NE-trending fault-line escarpment of crystalline Hudson Highlands; view of Central Valley (belt of early Paleozoic limestones)

Brecciated zones
Brecciated zones in Highlands gneisses at right (only evidence of steeply SE dipping border thrust at base of escarpment)

Last outcrop of Highlands crystallines (Pre-Cambrian)

View of Schunemunk Mt.
Passing over N. Y. Thruway; view (straight ahead) of Schunemunk Mt. (Devonian orthoquartzite and conglomerate).

STOP 5. Devonian Sediments
Cross railroad tracks to prominent outcrops along E-side of right of way. Devonian shaly sandstones (Oriskany-Esopus-Schoharie horizons)
Fossils:
Lower strata: poorly preserved sponges of type Titusvillia (?)
Leptocoelia flabellites, Leptaena rhomboidalis and other brachiopods
Middle strata: Spirophyton caudagalli (worm burrows or algal swish marks? ? )
Upper strata: Cypdcardinia (pelecypod)
Brachiopods (several genera)
Phacops and Dalmanites (trilobites) (confined to a single layer, hard to find)
Time will not permit to traverse across hill to E; in valley E of hill can be found (in descending stratigraphic order) Lower Devonian and Upper Silurian limestone (with corals), Silurian red shales (Longwood) followed by Lower Silurian conglomerate (Shawangunk) in Pine Hill beyond. Between Pine Hill and the Highlands escarpment to the E are beds of Wappinger limestone (Cambro-Ordovician). The exact structural relations between these stratigraphic sequences are not known with certainty. Westward across the valley of Woodbury Creek the shaly sandstones of the Highland Mills station appear to include the Hamilton group and are finally overlain by (Uppper ?) Devonian orthoquartzites and conglomerates of Schunemunk Mt. (a shallow syncline).
Approximately 1 mile to the north, along the E-side of the railroad, rocks of Oriskany lithology have been correlated with the Kanouse horizon (Onondaga) on good fossil evidence. (Eidman and Kindle. 1955)

Glacial delta deposits on both sides of narrow valley

STOP 6. Overthrust in Highlands Outlier
Walk S on Mountain road, crossing bridge to outcrop in hill at left (E) side of road (appr. 300 yds.)
Overthrust of Storm King granite (Pre-Cambrian) on intensely crumpled slaty shales of the Hudson River pelite group (Cambro-Ordovician).
Thrust plane dips rather gently toward the southeast. Small hill appears to be an outlier because Lower Paleozoic sediments have been found between it and the Highlands escarpment a short distance to the SE. Attitude of thrust plane here is atypical of Highlands border thrust which generally dips at high angles (70° in Delaware Aqueduct Tunnel E of Hudson River) to the SE.

STOP 7. Crow's Nest Lookout
View of middle Hudson gorge; West Point Military Academy on rock terrace below; Constitution Island with abandoned river channel; similar to Iona Island (Stop No. D-l), but on E-side of valley; Schooley Upland level E of the Hudson.

Large xenoliths
Large xenoliths of hornblende gneiss in pegmatite phase of Storm King granite at right (W)

Return
2010: Cross bridge and return by the same route taken to get here.