NYSGA 1989
NEW YORK STATE GEOLOGICAL ASSOCIATION
61st Annual Meeting
Middletown, New York
Field Trip Guidebook
Edited by
Dennis Weiss
Department of Earth and Planetary Sciences
City College of CUNY
Hosted by
Larry O'Brien
Department of Science and Engineering
Orange County Community College
PREFACE
The diversity of the geology of the Lower Hudson Valley and environs is reflected in the breadth of field trips contained in this guidebook for the 6lst Annual Meeting of the New York State Geological Association. No where in New York can one view, in an area of comparable size, such a wide variety ar rocks, structures, and sediments representing more than one billion years ar Earth history. Evidence of major events in the Earth's history and development ranging from periods of extreme deformation, to times of extensive sedimentation, to the breakup of continents, to the covering of the land by vast ice sheets are contained in the area's geologic sequences. In addition, modern problems in applied geology such as seismic risk and slope stability are also of particular concern.
Several of the field trips retrace the paths their authors led us on at previous meetings of the Association. Howard and Elizabeth Jaffe; Gordon Conally, Les Sirkin, and Don Cadwell; and Bob Finks update information presented at various meetings over the past twenty-nine years. It is with nostalgia that I remember that these were the first trips of the Association that I attended as a student. Moreover, some of you may recognize the art work of Jack Fagan which adorns the cover the guidebook. New views are presented by Pam Brock on the stratigraphy of the Manhattan Prong; by Tony Prave, Moses Alcala, and Jack Epstein on the nature of sedimentation in the middle and late Silurian; and by Alan Kafka, Margie Winslow, and Noel Barstow on the neotectonics of the Lower Hudson Valley region. Clearly, there is continuing interest in the Green Pond Outlier. Larry Malizzi and Alec Gates; Jim Mitchell and Randy Forsythe; and Bob Finks and Michael Raffoni present their respective interpretations of that area's geologic development. Triassic/Jurassic intrusive and extrusive igneous activity is examined by Jeff Steiner and John Puffer, respectively. Over the years the area of the Lower Hudson Valley has been extensively developed and the surficial deposits of the area disturbed. Despite this added difficulty, Les Sirkin, Don Cadwell, and Gordon Connally have been able to complete new studies of the Pleistocene geology of eastern Putnam County and Westchester County. As growth and development of the region have continued, the expansion of its highways has been accompanied by problems of slope stability. Clay Bolton's field trip will examine this concern which, in recent years, has led to catastrophe in several instances. Looking back into prehistory, this region has been occupied by man for over 6,000 years. Phil La Porta's presentation on chert, relates its stratigraphic occurrence to regional archeologic studies. Finally, as our concerns for science education increase, Bill Tucci and Bob Kalin in their "Geologic Climb of Schunnemunk Mountain" present a useful "hands on" teaching exercise for Earth Science teachers.
In closing, I would like to thank the authors of each trip for their effort and cooperation. Without them this guidebook would not be the professional reference and source of information it is. In addition, my gratitude goes to Jack Fagan for finding the time to do the cover of the guidebook, Jim Olmstead and Fred Wolfe for their wisdom and guidance, Larry O'Brien for his uplifting and cheerful support during the editing process, and finally to my wife Susan for patiently enduring the piles of manuscripts and edited texts left all over the house.
Dennis Weiss, Editor October, 1989

A1: STRATIGRAPHY OF THE NORTHEASTERN MANHATTAN PRONG, PEACH LAKE QUADRANGLE, NEW YORK-CONNECTICUT
PAMELA CHASE BROCK
Queens College and the Graduate Center of the City University of New York
INTRODUCTION
The purpose of this trip is to consider the stratigraphy of the Manhattan Prong along the New York-Connecticut border, in the Peach Lake quadrangle (Fig. 1). Recent mapping in this area has suggested that a major stratigraphic rev1s1on is necessary. Overlying the Grenvillian rocks of the Fordham Gneiss and below the magnesian marbles of the Cambro-Ordovician Inwood Marble, a traceable suite of metasedimentary and metavolcanic rocks appears to exist. This suite, here informally named the "Ned Mountain Formation", includes the K-feldspar rich quartzites typical of the "Lowerre Quartzite"; but it also contains a variety of other lithologies, all of which have previously been assigned to either the Fordham Gneiss or to post-Lowerre Paleozoic units. Ways in which rocks of the "Ned Mountain Formation" can be distinguished from other units will be pointed out on the trip and in the text.
Recognition of this new, expanded, Late Precambrian to Early Cambrian unit will have important implications both for the rift-to-drift stage of geological history and (by its map scale distribution) for Paleozoic structures in the Manhattan Prong.

A1: STRATIGRAPHY OF THE NORTHEASTERN MANHATTAN PRONG, PEACH LAKE QUADRANGLE, NEW YORK-CONNECTICUT

Station 1A. Fordham Gneiss and overlying Basal Member of the "Ned Mountain Formation"
The Yfiii member of the Fordham Gneiss is exposed on this hill. It consists of well-layered and compositionally heterogeneous coarse-grained, orthopyroxene-bearing gneisses. The scale of compositional layering ranges from about 2 cm to a meter. Some layers are highly leucocratic, dark layers are generally hornblende-rich. On close inspection, pitted and rust-stained orthopyroxenes can be seen on the weathered surface of the outcrop.
Here the Fordham largely retains its characteristic, poorly foliated Grenvillian texture. Locally, lineation defined by mafic minerals is evident. The effects of Taconian metamorphism can be seen in thin section: many orthopyroxenes are surrounded and embayed by cummingtonite and/or hornblende. Some pyroxene-bearing granite is present along the hill slope.
A number of small shear zones cut discontinuously across the gneisses. These seem to be related to an episode of post-Taconian shearing seen elsewhere in the northern Manhattan Prong. Age constraints from these areas suggest a Carboniferous age for the post-Taconian deformation (Brock and others, 1985; Brock and Brock, 1985 a & b).
After examining the Fordham, follow south along the cliff base for 60 to 100 meters to see the Basal Member of the "Ned Mountain Formation".
Here the Basal Member of the "Ned Mountain Formation" is a fissile, rusty-staining, graphitic granofels. The rocks are medium-to fine-grained, and contain quartz-K-feldspar-plagioclase-biotite-graphite±garnet. The tough Fordham gneisses form the crown of the hill, and the softer granofelses lie along its southern flank.
Biotite in the graphitic granofelses is concentrated into close-spaced (though discontinuous) streaks; as a result, the rocks tend to break into thin folia. This habit, and their K-feldspar-richness, distinguish the "Ned Mountain" granofelses from similar rocks in the Fordham and the Walloomsac. The graphitic, rusty-weathering granofels of the Fordham unit Yfy contains no K-feldspar and little biotite. Walloomsac granofelses are typically quartzplagioclase-biotite-graphite rocks containing little if any K-feldspar and breaking in a slabby fashion.
Fordham lithologies are truncated against the "Ned Mountain Formation". Where ZEnb is first seen, it is in contact with heterogeneous, layered gneisses; following the unconformity ˜30 meters southwest, largely leucocratic, homogeneous Fordham gneisses are against it; after another hundred meters large amphibolites lie at the unconformity; still further southwest, leuco-to mesocratic gneisses are in contact with the graphitic granofelses of ZEnb. Fordham gneisses adjacent to the unconformity tend to show the effects of Taconian metamorphism and deformation more than they do elsewhere. They are richer in biotite and have a better-developed foliation.
After finishing with this station, cross back to the east over the old dam. (The dam stands above the stream and swamp to the south of the hill.) Retrace your steps along the trail southwards for approximately 100 meters to the junction with a branch trail that climbs up to the east. Follow it east for ˜30 meters (Fig. 6). Then turn south off it to the outcrops of Station lB.

Station lB. Fordham Gneiss, Unit Yfv
Here Unit Yfv of the Fordham consists of well-layered, medium to coarse-grained, melanocratic to leucocratic gneisses. Plagioclase-quartz-hornblende-biotite-pyroxene±cummingtonite gneisses and amphibolite are present in the first outcrop. Rocks still showing the distinctive assemblage of YFv, garnet-clinopyroxene-plagioclase±orthopyroxene, can be seen in the outcrop further from the path. Partial replacement of this assemblage by hornblende (and of orthopyroxene by cummingtonite) is thought to have occurred during Taconian metamorphism. The assemblage has not been found in any rocks of post-Grenville age.
Next, proceed southeastwards through the bush looking for outcrops. When you reach the north-south trail marked with yellow dots, follow it southwards to the crest of the scarp overlooking Lake Windwing. En route you will see a good section through the metawackes, pelites, hornblende amphibolites and cummingtonite amphibolites of the ZEnw member of the "Ned Mountain Formation".

Station 1C. Wacke Member of the "Ned Mountain Formation"
As you walk, you will first pass outcrops of coarse-grained K-feldspar-plagioclase-sillimanite-garnet-biotite-quartz±graphite schist of the Basal Member. The rocks ara garnet-rich and contain prominent sillimanite trains; the contrast between the sillimanite-biotite-garnet and feldspathic segregations produces a pin-striped appearance. Metawackes of the Wacke Member, slightly higher in the section, have a similar pin-striped appearance but contain more quartz and less K-feldspar than the Basal Member.
A number of medium-grained granofelsic layers are present along the trail. These range from about 10 to 60 cm thick, and contain quartz-plagioclasebiotite-garnet±K-feldspar. Fine layering is often visible on close inspection.
Near the scarp several amphibolites are interlayered with the metawackes and granofelses. These include slightly greyish hornblende-cummingtonite-orthopyroxene bearing amphibolites and blacker orthopyroxene-free hornblende amphibolites.
The thick "pinstriped" metawackes, thin granofelses and hornblende amphibolites of the "Ned Mountain Formation" Wacke Member at this locality make it strongly resemble the Manhattan Schist. But in addition to the distinctive stratigraphic position of the "Ned Mountain", it can be distinguished from the Manhattan in several ways: a) while granofelses of the Manhattan contain little or no K-feldspar, those in the "Ned Mountain" in some places have substantial amounts; b) the Wacke Member is locally graphitic near its base, while the Manhattan contains no graphite; c) cummingtonite-bearing amphibolites have not yet been found in the Manhattan Schist; and d) bedding of the granofelsic layers in the Wacke Member thins towards the north, while no geographical variation is apparent in Manhattan Schist. At this locality, granofelses in the Wacke Member have similar thicknesses to those in Manhattan Schist, mostly between 5 cm and 1 meter. But about three kilometers to the north, granofels and hornblende-orthopyroxene amphibolite beds are both typically 1.5 cm to 8 cm thick, and 4.5 km to the north, many beds are ˜1 cm thick. This thinning is interpreted to reflect a southerly provenance for the sediments of the Wacke Member (Figs. 4 and 5).
Getting down the scarp is somewhat tricky. Good exposures of migmatized metawackes of ZEnw are present in the cliffs below, but for safety, it is better to follow the trail along the crest until it turns down. From the bottom of the slope, go to the spillway of Lake Windwing (at the lake's eastern end).

Station 1D. Calc-silicates, Arkosic Sandstones, and Pelite of the "Ned Mountain Formation, ZEnc member
K-feldspar-rich quartzite and clinopyroxene-K-feldspar bearing calc-silicate are interbedded on the south side of the spillway. Beds range from 5 to 50 cm thick. A biotite-rich pelite is present on either side of the spillway. This outcrop displays the thin northern variant of the Calc-silicate Member, which overlies the Wacke Member of the "Ned Mountain Formation". Shearing and pegmatite intrusion thought to be of Carboniferous age has resulted in local development of muscovite in the pelites and tremolite in the calc-silicate.

Station 1E. Inwood Marble
The Inwood here consists of well-bedded, white and buff weathering calcitic marble. The outcrop at the lakeside contains a bed of clean quartzite. Buff-weathering marbles contain the assemblage calcite-forsterite-dolomitephlogopite±periclase whereas white marbles contain calcite-dolomitephlogopite±periclase. Although quite rich in calcite, these are magnesian marbles typical of the Inwood.
The Inwood contains more carbonate and less silica and K2O than does the Calc-Silicate Member. It is also much less diverse lithologically. Marbles of the Calc-silicate Member of "Ned Mountain Formation" and Inwood Marble can be distinguished by their mineral assemblages (Fig. 3). Forsterite and phlogopite (occasionally spinel), ±clinopyroxene are typical constituents of the more magnesian, originally dolomitic Inwood. Clinopyroxene and K-feldspar are characteristic of both the low-magnesium Calc-silicate Member and Walloomsac marble.

STOP 2. OUTCROPS OF WALLOOMSAC SCHIST AND MARBLE
Here (Fig. 6) we see Walloomsac marble that was unconformably laid down over the Inwood (Table 1). Small outcrops of Walloomsac marble lie on either side of the road. These consist of well-bedded, rusty-stained, graphitic marble; they contain calcite-quartz-plagiaclase-K-feldspar-clinopyroxene ±phlogopite. Some coarse, late tremolite is present. Walloomsac marbles somewhat resemble calc-silicate rocks of the "Ned Mountain Formation", but differ from "Ned Mountain" in their distinctive rusty staining and in the abundance of graphite.
A few meters south on the west side of the road is a small outcrop of Walloomsac Schist. The Walloomsac here consists of a rusty-weathering, graphitic, quartz-plagioclase-biotite-garnet schistose granofels. K-feldspar-rich granafelses, typical of the Calc-silicate Member of the "Ned Mountain Formation", are never found in the Walloomsac.

STOP 3. CORDIERITE-BEARING WALLOOMSAC SCHIST
Slabby-breaking, rusty-staining, quartz-plagioclase-garnet-K-feldspar-sillimanite-cordierite graphitic schistose gneiss of the Walloomsac Schist outcrops here. More pelitic than at previous stop, the Walloomsac contains cordierite-sillimanite-garnet assemblages overprinted by K-feldspar-sillimanite-biotite. In thin section, garnets are rimmed by sillimanite against cordierite. The cordierites are rust-stained and obviously relict.

STOP 4. HARTLAND FORMATION AMPHIBOLITE AND GRANOFELS
Between Stop 3 and here, you have crossed Cameron's Line, the boundary between the rocks of the Manhattan Prong and the Hartland terrane (Fig. 2). Manhattan Schist, which elsewhere structurally overlies the Walloomsac, was cut out along this part of Cameron's Line. The Hartland was emplaced over the rocks of the Manhattan Prong early in the Taconian orogeny, and was later deformed along with them. At this outcrop, quartz-plagioclase-biotite granofels of the Hartland Formation is interlayered with hornblende-orthopyroxene±clinopyroxene amphibolite. Bedding ranges from 5 cm to 50 cm in thickness. The Hartland is distinguished from the Manhattan by its abundant amphibolites, its non-rusty, relatively garnet-poor granofelses, and its rhythmically interbedded schist and granofels sequences (meta-turbidites) not seen here.
A granite showing graphic intergrowth of quartz and K-feldspar and large books of biotite is also present at this outcrop. It contains no primary muscovite and is undeformed. It is thought to be late Taconian in age.
This completes a section from the Fordham Gneiss to the structurally highest rocks in the northern Peach Lake quadrangle. Next, we will examine a section in the southern part of the quadrangle.

STOP 5. CALC-SILICATE MEMBER OF THE "NED MOUNTAIN FORMATION", SOUTHERN SECTION
These outcrops are on private property. If you come by yourself, ask permission from the owners before looking. Outcrops are located at the end of the road and on the road's north side, by the driveway going north up the hill. Beware of poison ivy.
Inwood Marble lies in the bottom of the valley you have just driven across (Fig. 7). You are on the east limb of an F2 antiform, and will continue going down stratigraphically as you proceed west. Here in the southern portion of the Peach Lake quadrangle (Fig. 1), the Calc-silicate Member of the "Ned Mountain Formation" is much thicker than at Lake Windwing. At this locality, white-and-green clinopyroxene-bearing calc-silicates and marbles are interlayered with greyish, laminated, quartz-K-feldspar-plagioclase-biotite granofelses and hornblende amphibolites. Retrogressive tremolite and epidote is locally present in calc-silicate layers. The characteristic ribbing on the weathered surface of the calc-silicates reflects variations in bed-by-bed carbonate content. Some granofelsic layers are clinopyroxene-hornblende-bearing, but rich in K-feldspar whereas others are plagioclase-and biotite-rich. Modal K-feldspar in the granofelses varies from 20% to 70%, while quartz ranges up to about 60%. The granofelses show a faintly developed linear fabric.
Dikes of a Taconian granite lie in an axial-planar attitude to F2 folds. This granite is heterogeneously deformed; some parts show little foliation while others show a strong shear fabric. Small xenocrysts of calc-silicate and blebs of pyrrhotite are present in the granite. Although the granofelses (and related beds of granitic gneiss) and Taconian granites overlap compositionally, they can be distinguished by the following criteria: a) granofelses are essentially concordant, Taconian granites discordant; b) fabric tends to be homogeneously developed within the granofelses, heterogeneously in Taconian granites; c) K-feldspar rich granofelses do not generally contain sulfide, while Taconian granites can contain several percent. Layers of K-feldspar rich granofels, typically 2 to 10 cm thick, are scattered throughout the Calcsilicate Member in the south. Such layers have not been seen in the Inwood or Walloomsac marbles.

STOP 6. VOLCANICLASTIC MEMBER, "NED MOUNTAIN FORMATION"
K-feldspar-plagioclase-quartz granofelses of the Volcaniclastic Member (Fig. 7) outcrop to the east of the parking space; hornblende amphibolites outcrop to the west.
The Calc-silicate Member of the "Ned Mountain Formation" overlies and grades down into the Volcaniclastic Member in the southern Peach Lake quadrangle (Figs. 4 & 5). The Wacke Member is absent in the south: sediments here appear to have been largely volcaniclastic in origin. The granofelses in this outcrop are highly feldspathic, and include probable meta-tuff beds in the eastern end of the outcrop. Granofelses at the eastern end show thin (2 mm to 10 cm) layering, and generally contain little biotite. Occasional greenish clinopyroxene-bearing calc-silicate layers occur. Porphyroclasts and larger calc-silicate nodules containing plagioclase-quartz-clinopyroxene-hornblende are scattered through the granofelses. Some beds are relatively rich in biotite and quartz. A layer of amphibolite is present in the central portion of the outcrop; boundinaged amphibolites lie within the granofelses at the western end. These amphibolite layers appear to be related to the hornblende-clinopyroxene calc-silicate nodules and are probably of calc-silicate origin. The Volcaniclastic Member here clearly shows affinities to the granofelses of the Calc-silicate Member seen at Stop 5. Amphibolite within the Volcaniclastic Member at Pound Ridge (Figs. 2 & 4) also contains hornblende-clinopyroxene, but these minerals are restricted to amphibolitic layers there.
The hornblende amphibolite of the outcrop west of the pullout is fairly homogeneous. This amphibolite is about 15 m thick; it probably represents a metamorphosed basalt flow, but its origin remains uncertain. A Taconian granite at the west end of this outcrop has resulted in alteration to biotite.

STOP 7. CALC-SILICATE MEMBER, "NED MOUNTAIN FORMATION"
You have just passed the hinge surface of the F2 Taconian antiform. A D2 shear zone truncates the stratigraphy on the west side of the fold (Fig. 7). The Volcaniclastic Member is missing here, although it is present further north. At this location, one can see the repeat of the Calc-silicate Member on the west limb. Inwood Marble lies in the valley to the west.
On the west side of the road, near its intersection with Pettit Road, is an outcrop of white-and-green calc-silicate. The weathered surface of the outcrop shows the ribbed appearance typical of this unit. A highly sheared layer of "granitic gneiss" is present. It appears to be conformable and is tentatively interpreted as a rhyolitic ash bed.
At the end of the road are outcrops of fine-grained, purplish and grey quartz-K-feldspar-garnet-biotite±plagioclase granofelses and somewhat rusty, K-feldspar-rich metasaprolites. Metasaprolite is notable in outcrop for the abundant K-feldspar grains (1 cm to 5 cm in diameter) evident on the weathered surface. Biotite, sillimanite, and garnet are also present, but quartz (primarily in veins) is only ˜10% of the rock. The granofelses, present along side the metasaprolite, are quite different; quartz consists of 50%-80% of these rocks.
Although hard to see in outcrop, a cross-cutting foliation locally truncates the bedding. Thin section examination of the granofels reveals a highly sheared fabric defined by quartz ribbons. Here grain size in both the granofels and especially in the metasaprolite is unusually fine due to intense shearing. This shearing may be related to the D2 shear zone to the east.

STOP 8. MANHATTAN SCHIST
Turn right into parking lot opposite a church and beside the Lewisboro Police building. Intersection with Route 35 is in sight just ahead. From this parking lot we will walk to Stop 8, which is located at the east end of the roadcut on the south side of Route 35.
Route 35 is a narrow 2-lane highway with cars and trucks traveling fast in both directions. They do not have time or space to avoid errant pedestrians who pop out unexpectedly from the bushes! Because of this, it is safer to follow a route through the woods to reach the part of the roadcut where the ˜anhattan Schist is best exposed. (Most of rock exposed in the road cut is Taconian granite.)
Walk to the intersection of Spring Street with Route 35 and cross to the south side of Route 35. Walk east for -30 m to the sign for Route 35, then cut up through the bushes onto the bench above the highway. [The bench is covered by open woodland with no underbrush and is easier walking than the roadside.] Follow the top of the roadcut east for -300 meters, until the ground starts to drop off, and the roadcut is clearly decreasing in height. Climb down to road level. Be careful; a small stream lies between the roadcut and the road. There is little room to maneuver here.
Between Stop 7 and this outcrop, you have passed over Inwood Marble and Walloomsac Schist (Fig. 2). An outcrop of graphitic Walloomsac granofelses lies about 700 m east of Stop 8 on Route 35. At Stop 8, the structurally highest rocks in the southern Peach Lake quadrangle are exposed.
Interlayered amphibolite and quartz-plagioclase-biotite-garnet granofels of the Manhattan Schist are present at the eastern end of the outcrop. A dark, sooty stain (from the highway?) is present on many of the rocks. Some F1 isoclinal folding is visible in part of the amphibolite. Granofels beds vary from less than 1 cm to over 45 cm thick; a granofels-rich section extends for about 1.5 m. Proceeding westwards, the blocky granofels and amphibolites are followed by highly weathered metawackes. These rocks contain dark-colored biotite-garnet-sillimanite segregations and light-colored quartz-plagioclase veins and segregations. In thin section, biotite is brown, unlike the reddish biotite typical of the Walloomsac. As discussed at Stop lC, the Manhattan strongly resembles the Wacke Member of the "Ned Mountain Formation", but occupies a very different structural position.

A2: THE GREEN POND OUTLIER OF NEW YORK AND NEW JERSEY; A MESOSTRUCTURAL LABORATORY
JAMES P. MITCHELL
The Pennington School, Pennington, NJ 08534
RANDALL D. FORSYTHE
Department of Geography and Earth Science, UNCC, Charlotte, NC 28227
INTRODUCTION
Exposures of the folded Silurian and Devonian strata of the Green Pond outlier within the Reading Prong of New Jersey and New York (Fig. 1a.) contain abundant small scale deformation features. These include: slickenfiber faults, en echelon vein arrays, two sets of disjunctive cleavage, and small scale folds. This trip visits a series of outcrops within the outlier that permit a detailed study of the interrelationships and origin of these mesostructures.
Students of structural geology are commonly introduced to small scale (meso) structures classed as being either brittle or ductile. In the Earth, however, brittle deformation is not necessarily restricted to the upper "seismogenic" layer, and ductile deformation likewise is not restricted to the deeper medium to high grade metamorphic levels. Folds that form under moderate confining pressure and low temperatures, often reveal a confusing array of both ductile and brittle mesostructures. The manner in which these ductile and brittle features are related is one of the interesting topics that can be examined on this trip.
The trip also provides students an opportunity to understand some of the dynamic or stress conditions that operate during folding. Published work on folded strata (for discussion see Ramsay, 1967) has generally focussed on the geometric development of folds and its strain-related cleavages or foliations. The array of semi-brittle features that formed along with the cleavage in the Green Pond outlier permits an appreciation of the forces or stresses responsible for folding.

A2: THE GREEN POND OUTLIER OF NEW YORK AND NEW JERSEY; A MESOSTRUCTURAL LABORATORY

STOP 1. MESOSTRUCTURES IN THE UPPER GREEN POND CONGLOMERATE
The Green Pond Conglomerate forms the distant cliffs which probably lie unconformably on the Middle Proterozoic rocks beneath the lake. This is the eastern margin of the Green Pond outlier. Bedding dips northwest beneath the mountain. You are also located at the transition between the northern portion of the outlier defined by one large syncline and the central portion defined by three smaller wavelength anticline /syncline pairs. Superimposed on this NW dipping limb are two smaller anticline/syncline pairs that can be seen in this roadcut.
The purpose of this stop is to examine associations of the en echelon vein arrays, slickenfiber faults, and cleavage and to relate them to the paleostress directions and progressive folding.
Walk along the west bound lane about 100 m to the north face of the exposure. Beginning at the east end of the outcrop, walk about lO m until you see quartz veins at eye level.
a. En Echelon Vein Arrays. Several subhorizontal arrays of quartz veins occur in 'en echelon' arrangement (Fig. 11). Each array forms within a tabular shear zone and contains veins with a geometry that clearly indicates the sense of shear. In this case the top block moved westward (to the left). These features called en echelon vein arrays (EVA) have also been called tension gash arrays.
EVA Paleostress: The array and vein attitudes indicate (assuming type 1 geometry, see Figure 3b) that bedding parallel compression caused these particular EVA's to form. The direction of maximum compression that forms an EVA parallels the direction of greatest shortening which lies somewhere in the acute angle between the shear zone (array attitude) and a vein member (Fig.11).
Walk 30-40 m to the small Geodetic Survey sign located above a Bench Mark. See Figure 10 for location.
b. Slickenfiber Faults. Examine the many minor faults (Fig. 12) with lineations defined by mineral fibers, called slickenfiber faults (SFF 's terminology of Wise, et al., 1985). Profiles of these features show overlapping fibers and give a sense of displacement characteristic of SFF's . Note that the quartz filled pull apart structures along some of of the SFF's give a reverse sense of displacement. The "rough-smooth" method (Durney and Ramsay, 1973) also indicates reverse displacement. The exposed footwall surface feels smooth to the hand when rubbed upwards along the surface, therefore the hanging wall moved up defining a reverse motion. The rough-smooth technique is reliable for SFF's because fibers always lie in plates that are overlapped in one direction like the shingles on a roof.
SSF Paleostress: Most SFF surfaces here developed on crossbedding surfaces dipping more steeply to the northwest than the bedding. Thus beddin~g parallel compression indicated by the EVA's, may also represent a conjugate shear system with SFF's following steep planes of weakness in the rocks (crossbeds oriented suitably for slip in the given stress field) and EVA's forming subhorizontal shears across rock anisotropies and in more massive rocks.
Walk 7 m west of the Bench Mark. See Figure 10 for location.
c. Conjugate EVA's and SFF's. As sketched in Figure 13, conjugate SFF's and EVA's occur in concert. A subhorizontal SFF overprints an EVA with the same sense of displacement (top block westward) . This is conjugate to a steeply dipping bedding plane-SFF with veins whose displacement is top block upward to the east. These displacements are opposite but complementary such that the principal axes of shortening and compression bisects the two shears and is at a low angle to bedding. Lying in the intersection of the two shears is a quartz vein which is subparallel to the compression direction. This vein is common in conjugate EVA's and is a reliable indicator of paleostress directions.
Progressive Strain: Note the subhorizontal EVA veins in Figure 13 are sigmoidally shaped indicating progressive shear whereas, the steep EVA veins are straight, dilated, and incompletely filled with large quartz crystals (comb structure). This conjugate association can be seen in other places and may represent a slight rotation of the principal axis of compression towards the sigmoidally deformed EVA's (Fig.14). Such a rotation of the stress field, following the initial development of conjugate EVA, would substantially dilate one set of veins. This set will have straight tips which propagate at high angles to their array (synrotational EVA's of Fig. 8). The other set of veins will have curved tips that propagate at low angles to the array (antirotational EVA's of Fig. 8) .
Walk about 34 m to a position where purple rocks project slightly closer to the curb. See Figure 10 for location.
d. EVA and SFF Links. Again, SFF's occur on steep crossbeds, but this time several SFF's at eye level link up with EVA's higher in the outcrop to form a continuous shear zone with a mutual reverse sense of displacement (Figure 15). Furthermore, the same EVA's are paired with subhorizontal EVA's of the conjugate orientation. This is an outstanding association that clearly indicates the complimentary association of SFF's and EVA's in this area, and the conclusion that many of these features formed in response to maximum compression directed subparallel to bedding.
Importance of microcracking: What controls whether a shear zone will develop into a SSF or EVA? Certainly planes of weakness in the rock favor SFF development, but sometimes SFF's cut across rock anisotropies. We postulate that the microcracking distribution prior to rock failure determines the thickness of the shear zone and therefore whether SFF's or EVA's will develop (Fig. 16). For example, the linked SFF and EVA shear zones at this site may reflect an incipient zone of microcracking that was narrow at the base where the SFF end developed and wider at the EVA end.
Walk about 30 m to a southeast dipping limb and the core of an anticline. See Figure 10 for location.
e. Mesostructures Record Progressive Folding History. Beginning here two anticlines and synclines can be viewed in four sections (the median exposes two sections). Veining here is profuse and complicated. Some EVA's in the hinge zone are bent or curved with pronounced sigmoidal shapes. These veins are interpreted to have been formed early and then incrementally deformed during folding. In the median exposure (facing the west bound lane), there is a complex set of crosscutting veins that reflects rotation of the veins with respect to stresses during buckling. A late vein found here is suggestive of a late subhorizontal compression subnormal to a steep cleavage in an adjacent bed. Also in the cleaved bed (purple bed at the end of the median), is a conjugate EVA with compression bisecting the obtuse angle. Dissolution of veins at cleavage selvages confirms that this conjugate EVA was later shortened during cleavage development. Also, the veins of the subhorizontal EVA are sigmoidally deformed while the veins of the steep EVA are comparatively straight and dilated (as at site c.). This suggests that the principal stress field rotated away from bedding parallel compression as folding progressed (model shown in Fig. 8). This deformed zone may be very near the fault tip of a buried northwest-dipping reverse fault. It also parallels a steep northwest dipping reverse fault exposed about 100 m to the northwest in the median. In addition to the fault, two anticline-syncline pairs can be seen from both traffic lanes when walking northwestward along the median.

STOP 2. MESOSTRUCTURES !N THE BELLVALE SANDSTONE
The Bellvale Sandstone floors the road shoulder. Bedding dips NNW towards the axis of the major syncline that extends northeastward into New York State. You are at a position on the fold near the hinge where bedding begins to wrap around the nose of the plunging syncline. The purposes of this stop are to examine EVA's, cleavage and their geometric relations.
Cleavages: A pronounced spaced cleavage strikes about N 80 E subparallel to bedding and a faint cleavage strikes about N 60 E subparallel to the fold axis (time permitting, cleavages and bedding attitudes are more clear at the spillway bridge on Clinton Road, northern stream bank).
En Echelon Vein Arrays: A large EVA seen here indicates N-S shortening and compression (using the vein/array bisectrix rule for type 1 geometry). This stress field is roughly normal to the spaced cleavages and is postulated to represent a second discrete non-coaxial phase of deformation in the Green Pond outlier. Also note the occasional occurrance of unusually long vein tips extending beyond the EVA shear zone (Fig. 17). These veins when propagating out of the shear zone commonly curve into parallelism with the bisectrix of the vein and its array. This is the direction of the inferred maximum compression. If microcracks in the shear zone in part control vein attitudes then veins that propagate faster than others breakout of the array and may be free of the internal constraints that control intra-EVA crack tips. Thus the breakout veins are probably reasonably good indicators of the paleostress field.
Slickenfiber Faults: SSF offset some veins, most with apparent left lateral displacements. However, some of these have fibers that actually indicate dip-slip motions on NW dipping surfaces.

STOP 3. MESOSTRUCTURES IN THE LOWER skunnemunk CONGLOMERATE
You are in the same syncline as that present at Stop 2 but on the opposite limb. Beds of the lower Skunnemunk dip steeply SE towards the syncline axis. Rocks vary in color (gray, red, purple) and lithology (conglomerate, sandstone, muddy siltstone), typical of the Bellvale-Skunnemunk gradational contact. The main purposes of this stop are to: 1) see two cleavages, and 2) see unusually large EVA's that record hinge parallel compression.
Cleavage: Two spaced cleavages are visible in some of these rocks. One strikes northeastward subparallel to bedding and the fold axis, the other strikes N 85 E. They have the same general strikes as the two cleavages at Stop 2 suggesting two distinct periods of shortening.
En Echelon Vein Arrays: EVA's record a variety of paleostress directions at this site. Figure 10 shows EVA data compiled from Stops 3 and 4 (SE dipping limb only). Some EVA's on this limb of the fold record NW trending (steeply plunging) layer-parallel compression, but other indicate compression at high angles to bedding. These likely record early and late stages, respectively, of a progressive folding history.
Some EVA's in this area record more northerly directed compression. These directions are approximately normal to the N 85 E cleavage.
Unusually large EVA's record NE-SW trending compression directed subparallel to the fold axis. They contain large gently dipping veins often dilated and incompletely filled. Veins are typically one meter long, one meter wide, and spaced up to two meters apart. They likely formed late in the folding history once the fold axis was well defined. They may be an anisotropic response to the N-S directed shortening by other EVA and compatible with the N 85 E cleavage.
Slickenfiber Faults: Most SFF's are bedding plane and cross bedding slip surfaces that record NW trending displacements that are compatible with major folding and NE trending cleavage development.

STOP 4a. MESOSTRUCTURES IN THE UPPER SKUNNEMUNK CONGLOMERATE
You are located on the same SE dipping limb as at Stop 3, but in this case we are hiking up the hill to the east (up section) into the axis of the syncline. The purposes are to observe numerous SFF's, EVA's, and a distinct N 85 E cross cleavage. Lock the vehicles, and hike eastward up the mountain along the right side of the pipe line clearing. Although the hike is perhaps strenuous to some, the geology and scenery (at Terrace Pond) makes this a worthwhile endeavor.
As you work your way up the ridge keep an eye out for the trail head of the Bue Dot Trail that will take us to Terrace Pond (0.3 miles up the gas line clearing). Before heading in, however, there are exposures under foot in the pipe line clearing near the trail head worth a bit of investigation.
Slickenfiber faults: The outcrops under foot in the pipe line clearing contain exposures of conjugate SFF's. Also, along the forest edge opposite the entrance to the trail is a slip surface worthy of close examination. Here, the SFF surface has two directions of fibers. Upon inspection you should be able to discern their relative timing. A N-S oriented set of fibers has been superimposed over a NW-SE oriented set, and suggests a clockwise shift in the axis of maximum compression.
En echelon vein arrays: The EVA's here largely record NW-SE trending shortening compatible with folding and most SFF's.

STOP 4b. Terrace Pond.
Now proceed into the woods on the Blue Dot Trail to Terrace Pond (0. 4 miles). Along the way are a discontinuous series of exposures within which various mesostructures can be examined.
Cleavages: A distinctive spaced cleavage occurs throughout this area that trends obliquely to the fold axis at about N 80 E. It crosses both limbs and can be seen on both sides of the pond (see Figure 18 for cleavage and bedding) The far cliff descending into the pond is the opposite limb of the syncline (bedding: N 35 E, 75 NW). You are standing on the western limb that forms the west margin of the pond (bedding: N 22 E, 30 SE) . The fold axis is submerged. Many mesostructures can be seen along the White Dot Trail that circles the pond. For example, on the west margin an excellent pair of intersecting conjugate EVA's record a near N-S trending compression compatible with cleavage formation in the same rocks (see Fig. 19).
Field Exercise for Students. This location is an excellent choice for conducting a field-base lab in mesostructural analysis. Structure students can be taught how to recognize, measure, and interpret SFF's and EVA's along the trail on the way in to Terrace Pond. Then, working around the pond on the White Dot Trail they can collect their own data, first on the west limb, and then on the east limb. The data can be plotted later on stereonets and used for making an interpretation of the paleostress history in the area. Sample data spreadsheets, and a crib sheet for measuring EVA's are shown in Figure 20. The scenery and wilderness setting certainly adds a sense of spirit and adventure to what might otherwise be thought of as a rather tedious exercise.

A3: STRUCTURE AND PETROLOGY OF THE PRECAMBRIAN ALLOCHTHON AND PALEOZOIC SEDIMENTS OF THE MONROE AREA, NEW YORK
The area covered by this trip lies in the northern part of the Monroe 7 1/2′ quadrangle, New York, and consists of a folded and faulted complex of autochthonous Precambrian gneisses, Lower Cambrian through Middle Devonian sediments and allochthonous Precambrian gneisses. Geologic maps covering the trip area have been published by Ries (1897), Fisher, et.al. (1961), and Jaffe and Jaffe (1962). Unpublished maps prepared by Colony and by Kothe (Ph.D. thesis, Cornell Univ.) undoubtedly contain valuable information but are not available for study. Recent workers in adjacent areas include Dodd (1965), Helenek (in progress) and Frimpter (in progress), all in the Precambrian autochthon, and Boucot (1959) and Southard (1960) in the stratigraphy and paleontology of the Paleozoic sediments. The work of Colony (1933), largely unpublished, is impressive.
This article is reproduced (with minor editorial changes) from the New York State Geological Association Guidebooks of 1962 and 1967. The log has been modified to reflect road changes in the last 22 years.
HOWARD W. JAFFE, University of Massachusetts
ELIZABETH B. JAFFE, Amhurst, Massachusetts

A3: STRUCTURE AND PETROLOGY OF THE PRECAMBRIAN ALLOCHTHON AND PALEOZOIC SEDIMENTS OF THE MONROE AREA, NEW YORK

STOP 1. ORECO TERRACE: BELLVALE GRAYWACKE
The outcrop is on the right side of Oreco Terrace just above the intersection of N.Y.208, Orange and Rockland Road, and Oreco Terrace. Here, the Bellvale graywacke of the Hamilton Group (Middle Devonian) is exposed in a section approximately 220 feet thick. It consists of 20 - 40 foot beds of dark blue-gray, green-gray, or gray, fine-to medium-grained (0.08 - 0.25mm average grain size) lithic arenite or graywacke, rhythmically interbedded with thin beds of dark green-gray to blue-gray shale. A representative modal composition of the graywacke follows:
Mode Of Bellvale Graywacke
Detritals: | |
| quartz | 20%
| oligoclase | 2
| shale phyllite | 44?
| siltstone chert | 15
| greenstone | 1
Matrix: | |
| clay, sericite, chorite, Mn oxide | 15?
Metamorphic: | |
| chlorite | 2
| muscovite | 1
| | 100%
Texturally, the rock consists of angular, elongated slivers of detrital quartz and predominantly phyllitic rock fragments (0.08 - 0.25mm) set in a fine matrix of sericitic muscovite, clay, and chlorite. It is often difficult to distinguish smeared-out phyllitic fragments from balled-up micaceous matrix, both of which frequently blend or flow together. Depending upon the uncertainty of the matrix content, or the classification used, the Bellvale is either a low-rank graywacke (Krynine, 1948), a subgraywacke or a lithic graywacke (Pettijohn, 1957) or a graywacke (Folk, 1954). Larger bent grains of chlorite and muscovite in the matrix, are here interpreted to have grown from fine matrix material marking the beginning of the chlorite zone - greenschist facies of regional metamorphism imprinted during the Appalachian orogeny.
In general, the Bellvale graywackes tend to show rhythmic interbedding with shale, with graded bedding low in the section and strong current crossbedding higher in the section. Occasional brachiopods are found low in the section; plant fossils are found higher up. Both features suggest gradation from marine to non-marine depositional environment. The provenance was a low-rank metamorphic or sedimentary terrane.
The shattered outcrop at Oreco Terrace is at the southwest corner of Rotated Block 8 (Fig. 2) and lies near the intersection of four directions of faulting. Attitudes of prominent structures at the outcrop are tabulated:
| STRIKE | DIP
Bedding, Cgl., North end of hill | N 8 E | 77E
Bedding, Cgl., North center of hill | N 59 W | 70NE
Bedding, Cgl., Center of hill | N 27 W | 50NE
Cross-fault | N 77 W | 90
Bedding, Qtz., South end of hill | N 2 W | 60E

STOP 2. GOLF RANGE: SHAWANGUNK CONGLOMERATE
The Shawangunk conglomerate and quartzite (Greenpond conglomerate unit) of Lower to Middle Silurian age occurs in a series of small outcrops extending northeastward along the western edge of skunnemunk Mountain syncline. At this stop the Shawangunk forms a small, relatively inconspicuous topographic knob as contrasted with its occurrence near Stop 5, where the same unit forms the spine of the steep, southeast-facing escarpment of Lazy Hill. At the present stop the Shawangunk consists of about 75% buff pebble conglomerate intercalated with 25% fine-grained green-gray quartzite.
The conglomerate consists of white pebbles of milky vein quartz (averaging 15 - 40mm in length) in a matrix of finer pebbles and grains of rounded quartz, all cemented by secondary silica and buff-orange-red ferric oxides. Occasional pebbles of white orthoclase are present as are black pebbles consisting of green tourmaline and quartz. The color of the weathered surface of the outcrop varies from pink (hematite) to yellow-brown (goethite) or black (manganese oxide dendrites) with some green contributed by lichens.
The pebbles, obviously well-rounded when deposited on the Late Ordovician erosion surface, have taken on a secondary angularity and elongation due to stretching, crowding, rotation, and slippage in the bedding planes produced during Paleozoic orogenies. Most of the pebbles show maximum elongation parallel to the fold axis (b-fabric axis). Many of the pebbles have been corrugated and a large number are cracked and sliced parallel to the b-c fabric plane. Bedding surfaces are slickensided, fluted, and warped parallel to the a-axis (down-dip). The fine-grained, gray-green interbedded quartzite is composed of quartz and minor orthoclase cemented by authigenic quartz, muscovite and chlorite, and Fe-oxides.
The elongation and shattering of the pebbles here at Lazy Hill to the south-west greatly exceeds that observed in pebble beds in Lower and Middle Devonian rocks (Connelly conglomerate of Oriskany age, and Bellvale graywacke, respectively) in this area, suggesting that the Shawangunk was involved in an additional deformation episode of possible pre-Oriskany age.
A pre-Acadian, Silurian deformation period in New York was reported by Megathlin (1939) and discussed by Kay (1942). The sporadic outcrops of Shawangunk quartzite to the north along the western limb of the skunnemunk Mountain syncline are all heavily silicified and sheared, again much more so than quartzites of Oriskany and Bellvale age.
The conglomerate and quartzite outcrop is S-shaped, with the attitudes of the bedding and a cross-fault as follows:
| STRIKE | DIP
Bedding, Cgl., North end of hill | N 8 E | 77E
Bedding, Cgl., North center of hill | N 59 W | 70NE
Bedding, Cgl., Center of hill | N 27 W | 50NE
Cross-fault | N 77 W | 90
Bedding, Qtz., South end of hill | N 2 W | 60E
The cross-fault displaces the stratigraphically higher Shawangunk quartzite member to the west, putting it on strike with the lower conglomerate member of the Shawangunk Formation. On first viewing the outcrop, the alternating pebble beds and fine feldspathic quartzites lead one to suspect that the beds are overturned. On close inspection this does not appear to be the case.

STOP 3. MUSEUM VILLAGE KLIPPE: ALLOCHTHONOUS PRECAMBRIAN LEUCOGNEISS RESTING ON CAMBRO-ORDOVICIAN WAPPINGER DOLOMITE
From the Old Mansion Road cut in the Precambrian Museum Village klippe, look south across the N 75°W-trending Quickway crossfault. The ridge due south is the Bellvale synclinal extension of skunnemunk Mountain. The next ridge to the west is Lazy Hill, held up by Shawangunk conglomerate, and offset from the Golf Range Shawangunk conglomerate of Stop 2. To the west of Lazy Hill, the next prominent ridge is the Goose Pond Precambrian klippe, formerly continuous with the Museum Village klippe and now offset about 2 miles along the Quickway cross fault.
Museum Village klippe is a thin, synclinal, saucer-shaped slice of gray-white albite-quartz-microperthite leucogneiss that has survived five or six orogenies. The rock of the allochthon were deposited as a clastic wedge (molasse) in a reducing environment, perhaps as long as 1500 million years ago; they were folded and metamorphosed to the sillimanite-almandine-orthoclase metamorphic grade about 1100 million years ago; thrust from the east in Taconic or Late Ordovician time; refolded and faulted in Taconic time; possibly again in Acadian time; refolded and faulted in Appalachian time; and finally shattered by Triassic block faulting and associated block rotation. In outcrop, the leucogneiss is heavily shattered and slickensided with lineations often running in three directions at a given place. Quartz grains and pebbles are stretched into thin corrugated tongues and sheets showing elongations of 15:1 and 20:1 parallel to the b- and a- fabric axes. Over most of the outcrop, biotite and garnet are extensively retrograded to chlorite, and abundant calcite veinlets cross at all angles.
Towards the central and western part of the cut there occur occasional thin layers rich in fresh biotite and uncommonly coarse laths (not needles) of fresh blue-gray sillimanite that have survived the complex orogenic history. As none of the Cambro-Ordovician or younger rocks in the area show any metamorphic grade higher than chlorite zone metamorphism, the sillimanite is assumed Precambrian in age, and its preservation in large fresh grains in an otherwise extensively retrograded outcrop is remarkable.
Modal analyses of samples collected along an east-west traverse across the Museum Village klippe follows:
| | Sample Number |
| East Side | Center | West Side
Almandine-pyrope | 0.1 | 2.0 | - | -
Tourmaline | - | + | + | -
The presence of albite in the most retrograded gneisses of this and the other allochthonous Precambrian blocks studied, fairly consistently suggests that it may be a retrograded mineral after an originally more calcic plagioclase. The K-feldspar in all of these rocks is microperthite (usually microcline microperthite) and is indicative of a temperature of Precambrian metamorphism of the order of 600°C. The presence of two plagioclases, one as free grains and the other exsolved in microcline microperthite, is characteristic of many of the granitic gneisses of both the autochthon and the allochthons. In some of the allochthonous leucogneisses, the microperthite and the albite tend to occur in separate bands which may reflect original compositional differences.
Return to the cars and cautiously descend the hill to the left to the Quickway (N.Y. 17-West/U.S. 6). Beware of high speed traffic and stay close to the outcrop which parallels the highway. Walk to the extreme west edge of the roadcut where the Precambrian leucogneiss rests in overthrust contact on the light gray Cambro-Ordovician Wappinger dolomite. Note the occasional flat-lying, slippery fracture planes of the contact.
The metamorphic layering in the allochthon dips to the east whereas the dolomite bedding dips predominantly west.
The average foliation of the leucogneiss is N33°E, 20°SE. The average attitude of the dolomite beds is N22°W, 35°W. Prominent faults in the klippe parallel the metamorphic layering and trend N22°E, 20°SE. The fault contact of the dolomite and the klippe is irregular and has the same general attitude. Both the dolomite and the klippe are cut by vertical faults trending N27°W.

STOP 4. GREEN POND MOUNTAIN: PRECAMBRIAN ALLOCHTHON OVER OVERTURNED HUDSON RIVER PELITE.
Observe black, fissile Hudson River shales (Middle? Ordovician) in the road cut at the northwest edge of the Precambrian allochthon. Careful observation will show that the attitude of the bedding and cleavage is N78°E; the bedding dips 70°S and the cleavage 40°S. This indicates that the outcrop is on the limb of an overturned fold with the synclinal axis north. The shales both here and at Bull Mine Mountain klippe to the north are all wildly folded and overturned close to the overriding Precambrian allochthons.
Many of the Hudson River black shales are calcareous, and consist of fine laminae (0.05 ~ 0.1mm) of dolomitic silt or mud (marl) intercalated rhythmically (occasionally cross-bedded) with carbonaceous shale. An estimated thin-section mode of a representative Hudson River "shale" follows:
| Mineral | Calcareous laminae | Mineral laminae
Detritals and matrix | | |
| dolomite, calcite | 30% | 5%
| plagioclase, microcline | 10 | +
| mica, clay, chlorite | 15 | 50
| carbonaceous matter, graphite | - | 15
| pyrite | - | +
Metamorphic: | | |
| chlorite, muscovite, biotite | - | 5
| | 100% | 100%
Walk about 100 - 150 feet into the woods southwest of the shale outcrop on N.Y. 17M. A moss-covered rubble of shale, dolomite, and "limonitized" fault breccia indicate where the covered contact has been crossed. The edge of the Precambrian allochthon of Goose Pond Mountain is found about 130 feet south from the road, and the first rock found in place is a graphitic calcareous quartzite of which sample No. 527 is representative.
Return to the cars and drive 0.4 mi east on N.Y. 17M, stopping at a white albite-quartz-microcline microperthite leucogneiss (sample No. 20), in places graphitic, biotitic or rarely, garnetiferous.
Note the extreme elongation and smearing out of quartz pebbles and grains similar to that seen at the Museum Village outcrop of Stop 3. Further to the east, the rocks become increasingly calcareous (sample No. 788). At the extreme eastern edge, prehnitized calc-silicate leucogneiss is interlayered with some amphibolite, the latter of probable basic volcanic origin. Modes of representative rock types of the Goose Pond allochthon follow:
Modes Of Gneisses Of The Goose Pond Mountain Allochthon
| | Sample Number |
| East Side | Center | West Side
Brown Hornblende | 0.2 | 33.0 | - | -
Here, as in the Museum Village klippe of Stop 2, the greatest amount of retrograding occurs at the eastern and western margins of the allochthon with some fresh rocks occurring near the center. If the klippen are indeed synclinal saucers the presently exposed centers of the masses would lie at a further distance from the sole of the thrust and would be expected to show less alteration. It should be emphasized that the Precambrian autochthonous gneisses in the southern part of the Monroe quadrangle (Jaffe and Jaffe, 1962) are not comparably retrograded except near Triassic border faults.

STOP 5: Shawangunk Quartzite
STOP 5. LAZY HILL - SHAWANGUNK QUARTZITE
Walk 0.2 miles west crossing buried northeast-trending fault contact between the Shawangunk ridge of Lazy Hill rising steeply ahead and the Bellvale ridge of Durland Hill to the rear. Walk to the north nose of Lazy Hill (permission of the owners, the Durlands, is necessary) where a large outcrop of Shawangunk quartzite is exposed. The rock is a thin-bedded, pink, buff and white orthoquartzite consisting of:
Mode of Shawangunk Orthoquartzite, Durland Property
Quartz | 93%
Chert | 5
Sericite, Chlorite | 2
Zircon | +
Hematite | +
Goethite | +
Pyrite | +
Green tourmaline | +
| 100%
|
The quartz grains are well-rounded, moderately elongated, well-sorted (average diameter, 0.75mm), and the rock is very tightly cemented. Each grain of quartz is cemented to another by authigenic quartz overgrown in optical continuity with the detrital cores. Undulatory extinction due to deformation passes through the core and overgrowth of each grain. The Lazy Hill ridgetop to the south (not visited) is formed of a coarse white pebble conglomerate interbedded with white orthoquartzite (occasionally ripple-marked) and grades eastward to a red arkosic conglomerate below the ridge-top. Quartz pebbles and orthoclase pebbles are strongly elongated (3:1 and 4:1) and heavily shattered and veined in both the red arkosic and the white conglomerate.

STOP 6. MONROE BOWL-0-FUN: CONNELLY (ORISKANY) -ESOPUS CONTACT)
2012: Monroe Bowl-O-fun burned down in 1997.
The outcrop at Monroe Bowl-0-Fun originally was described by Jaffe and Jaffe, (1967) to consist of about 300 feet of the Esopus Formation underlain at the rear of the cut by red and white pebble conglomerate, the Connelly Conglomerate of Oriskany age. Most of the exposure has been covered by a railroad tie retaining wall. Here, a small outcrop of the Connelly is still exposed to the far right near the gasoline service station, and was described by Jaffe and Jaffe (1967) to consist weathered yellow, "limonitic" conglomerate (3 ft or more), succeeded by white to buff, pebble-bearing orthoquartzite (5 ft), which is in turn overlain by bright red hematitic quartzite (10 ft). The pebbles in the Connelly conglomerate are of white, round to slightly elongated quartz, averaging 1-2 mm in maximum dimension. The Connelly is disconformably overlain by a lowermost member of the Esopus Formation, recognized by Southard (1960). A small exposure of the Esopus Formation is exposed at the far left of the retaining wall. The attitude of both the Connelly and the Esopus at their contact was described to be N68°E, 45°N. A heavily slickensided fault surface, trending N53°, 60°SE cuts across the Connelly beds and presumably also cuts the overlying Esopus Formation.
The lowermost member of the Esopus, at its base, consists of fissile, bluegray siltstones which weather to brown and orange on cleavage surfaces. Many of the rocks are marked with Taonurus cauda-galli on bedding planes. At this outcrop the authors have collected a remarkable fauna including a specimen of the giant trilobite, Coronura myrmecophorus, not previously reported from the Esopus Formation. According to D.W. Fisher, New York State paleontologist who identified the specimen, it has previously been reported from the Schoharie and Onondaga Formations. The specimen was donated to the N.Y. State Museum collection.
The lowermost member is also relatively rich in conulariids, none of which have yet been identified. Other fauna include the brachiopods: Leptocaelia flabellites, Schuchertella sp., Acrospirifer macrothyris as well as some chonetid and orbiculoid genera. Platystomid and loxonemid gastropods, rugose corals and a dalmanitid trilobite were also collected by the authors.
The lowermost member grades into the black, poorly fossiliferous Lower Mudstone member which in turn grades into a purple sandstone at the north end of the 350 foot exposure. The sandstone is presumably the lower part of the Highland Mills member of the Esopus Formation. The fauna of the lowermost member at the Bowl-0-Fun appears to differ significantly from that of the Highland Mills member of the Esopus Formation found at Bakertown and Highland Mills (described by Boucot, 1959). The fauna should receive some serious study by specialists before the outcrop is demolished by new construction.

STOP 7. ORANGE TURNPIKE: POUGHQUAG QUARTZITE (LOWER CAMBRIAN)
Walk 0.16 miles due west over hilltop to the edge of a cliff formed by a 10 foot section of the Poughquag Formation (Lower Cambrian). The section consists of alternating 2 inch to 2 foot thick beds of ferruginous orthoquartzite, conglomerate, and arkose, striking N75°W and dipping 8°N, overlying the vertically dipping Precambrian autochthon with marked angular unconformity. This represents original sedimentary onlap with gentle warping or folding in subsequent geologic time.
Apparently the Precambrian Monroe Massif (Block 2) was sufficiently rigid throughout the Paleozoic to prevent the deformation of the overlapping embayment of Poughquag quartzite and Wappinger dolomite. This is indicated by both the gentle warping observed and also by the relative sphericity of the quartz pebbles in various Poughquag beds.
Several of the beds are feldspathic, a feature uncommon in the Poughquag of the Poughkeepsie Quadrangle (Gordon, 1911). One such bed at the Monroe outcrop is a conglomeratic arkose which is a true high rank arkose in the sense of Krynine (1948). A remarkable textural feature of this rock is the abundance of authigenic feldspar (microcline?) which is the principal cementing medium in sample No. 466. The specimen consists of 1-2 m quartz and microcline pebbles (all very round) lying in a matrix of authigenic microcline (?) cement which is clear in appearance. Some sawtooth or hacksaw terminations on the detrital microcline cores (Edelman and Doeglas, 1931) indicate that interstratal solution has taken place after deposition, presumable in situ. The authigenic feldspar overgrowths show only weak twinning when grown around detrital cores showing strongly developed microcline twinning. A mode of such rock is as follows:
Mode Of Lower Cambrian Poughquag Conglomerate Arkose Specimen No. 466
Microcline | 47.4%
Microcline microperthite | +
Quartz | 48.6
Albite-oligoclase | +
Muscovite | +
Rutile, Anatase, Tourmaline (green + brown) | 0.5
Zircon | 0.5
Hematite  } |
} | 3.0
Mn oxides} |
| 100.0%
The mineralogical composition of the Poughquag at Monroe leaves little doubt that it was derived from erosion of the granitic gneisses it overlies.
On the return walk to the road, stops may be made at exposures of post-Wappinger lamprophyre dikes which the authors believe to be of late Ordovician age (Jaffe and Jaffe, 1962). The authors have studied the dikes in considerable detail and would suggest a possible age of intrusion similar to that of the ultramafic intrusion of the Cortland Complex at Stony Point, New York (Ratcliffe, 1967). The Cortland Complex has been dated by Long and Kulp (1962) at 435 million years by K/A isotopic ratios obtained on biotite from the complex, a date close to the accepted Ordovician-Silurian boundary. An age of 398+17 m.y. was obtained from Ar /K ratios on the amphibole (kaersutite) phenocrysts in one of these dikes (Jaffe and Jaffe, 1973). This age may be a bit low because of argon loss during a regional Paleozoic reheating· These ages were run some years before development of more refined Ar/Ar methods now in use.
Thus, lamprophyre dikes of deep-seated (mantle-derived?) origin are not restricted to Mesozoic and Tertiary ages. They may range from Precambrian to Recent (Zartman, et al., 1967).
Stops 8, 9, 10, 11, and 12 (Fig. 3) are located in the granulite facies gneisses of the authochthonous block, here called the Monroe crystalline massif of Precambrian (Proterozoic) age. For reemphasis, we note that the gneisses of the authochthon do not show the pervasive retrograde alteration and extensive mineral stretching that characterize the rocks of the allochthon.
The prevalence of hypersthene and total absence of muscovite from folded gneisses of the Monroe crystalline massif verify that regional metamorphism took place in the granulite facies. The omnipresent coexistence of hypersthene with augite in mafic rocks; hypersthene-K-feldspar association in granitic gneisses (charnockite); sillimanite-K-feldspar assemblages in pelitic gneisses; Fe-rich cordierite-sillimanite-K-feldspar-almandine-tourmaline assemblages, also in pelitic gneisses; and copious exsolution of pigeonite in host hypersthene collectively indicate that metamorphism occurred at T = 700 - 800°C, at p = 2-4 kbars (7-14 km depth) (Jaffe and Jaffe, 1973).

STOP 8. ORANGE TURNPIKE: QUARTZ-OLIGOCLASE GNEISS
Leaving Stop 7, the Orange Turnpike turns southwest and crosses the concealed unconformable Cambrian-Precambrian contact. The quasi-horizontal Poughquag and Wappinger beds overlie vertically dipping Precambrian gneisses, permitting the delineation of a major unconformity, unfortunately not exposed in the area. Beyond the Lipalian interval, the first rock encountered is a fine-grained pink alaskite composed mainly of 1-3 mm microcline-microperthite and quartz, minor sericitized albite-oligoclase and an occasional flake of biotite. Within 100 ft to the south, the pink alaskite grades through a narrow zone of coarse biotite-microperthite-oligoclase granite and granodiorite into a medium-grained (2 mm), gray, essentially massive hypersthene quartz diorite gneiss which forms the bulk of the outcrop. It is variously called quartz oligoclase gneiss or enderbite by other workers. It contains: oligoclase 70%, quartz about 25% and hypersthene, biotite, magnetite and chlorite about 5%. In thin section, quartz is not uniformly distributed but rather forms long tongues which embay adjoining oligoclase grains; these are well twinned and antiperthitic. On top of the outcrop, observe several lenses of biotite-hornblende-hypersthene-labradorite (An55) pyribolite infolded in the quartz diorite gneiss. Foliation measured on the pyribolite is N35° to 50°E, with a dip close to 90°. Slickensided joint faces strike N24° to 65°W. About 0.3 mi south (not a scheduled stop) the quartz diorite gneiss darkens in color, the quartz content drops markedly, and the rock grades to an augite diorite gneiss interlayered with hornblende-hypersthene-andesine pyribolite. Where quartz becomes locally abundant, it embays and replaces both plagioclase and the ferromagnesian minerals.
Hypersthene-quartz-oligoclase gneiss (quartz diorite gneiss) is thus formed from the metamorphic reconstitution of pyribolite accompanied by the introduction of silica and small amounts of potash. These constituents could logically be derived from anatectic granitic liquids derived from the fractional melting of sedimentary precursors.

STOP 9. HARRIMAN HEIGHTS ROAD: CALC-SILICATE MIGMATITE
A fresh roadcut exposes a dark gray, green, and pink banded migmatite. The gray rock is a calc-silicate paragneiss composed of quartz, microcline, bytownite (An80), augite, green epidote (pistacite), dark brown sphene (titanite), zircon, apatite, and magnetite. The pink bands consist mainly of quartz and microcline or microcline microperthite. Other samples of this migmatite contain almost pure anorthite (An95). Epidote, common throughout the region in calc-silicate units, evidently formed by retrograde metamorphic alteration or exchange of Ca, Al, Si, and Fe in anorthite+augite, in a wet oxygenated environment.

STOP 10: ORANGE TURNPIKE: CAMPTONITE DIKE CUTTING HORNBLENDE GRANITE GNEISS
The outcrop on the west side of the road shows a 20-25 ft dike of lamprophyre called camptonite forming the low pavement of the outcrop. It strikes N38°W and dips 86°NE. The dike contains green hornblende phenocrysts up to 1/4 in lying in a matrix of albite laths, 0.2 x 0.4 mm, which, in turn enclose granular epidote. In these rocks, it appears that deuteric alteration of an initially more calcic (intermediate) plagioclase has resulted in the growth of albite+epidote. The camptonite contains: albite - 53.3%, hornblende - 21.5%, epidote - 12.6%, chlorite - 7.3%, and apatite+opaque+calcite+quartz+k-feldspar - 5.3%.
The country rock intruded by the dike is the hornblende granite gneiss that makes up about one-quarter of the volume of the Monroe crystalline massif and is also widespread in the other areas that constitute the Hudson Highlands. In the Monroe block, these granitic gneisses are uncommonly iron-rich and the hornblendes are ferrohastingsites with 100Fe/(Fe+Mg) = 86 that coexist with Ti-and Fe-rich biotites in which 100Fe/(Fe+Mg) = 90, ratios found in minerals at this outcrop. Here, the granite gneiss contains occasional schlieren of very biotite-rich rock.

STOP 11. EAST MOMBASHA ROAD: LEUCOPHYRE DIKE INTRUDING AMPHIBOLITE
Stop 11 shows a 16 ft thick granodiorite leucophyre dike which strikes N48°W, cross-cutting the foliation of the surrounding amphibolite which strikes 57°E and dips 20°S. Note the large wedge of amphibolite in the center of the dike and the occasional pink K-feldspar-quartz bands in the amphibolite. This dike is unique in the Monroe quadrangle, and perhaps in the Highlands. It shows sparse pink phenocrysts of oligoclase, quartz, less microcline and biotite lying in a dark gray matrix, which is again porphyritic on a microscopic scale. The second generation of microphenocrysts is made up of square to rhombic zoned potash feldspar and laths of albite-oligoclase. These lie in a very fine granophyric groundmass made up of feldspar, quartz, mica, chlorite, "limonite" and manganese oxide. The extremely fine-grained oxides form megascopic crenulated black streaks which give the dike a distinct flow layering in parts of the outcrop. A mode was not obtained because of the fine nature of the matrix. X-ray data on a powdered sample indicate that oligoclase>quartz>microcline, hence the dike is of granodioritic composition. East of the road, the dike is not found, and may be cut off by a north-south fault; if so, the dike is very old. An outcrop of the same rock was found 0.25 mi to the west cutting migmatite; it may be an extension of the same dike.

STOP 12. EAST MOMBASHA ROAD: PELITIC PARAGNEISS
This is a tightly folded, crenulated pelitic paragneiss in the sillimanite-K-feldspar zone of metamorphism. The outcrop consists of thin bands of gray biotite-microcline-labradorite-quartz gneiss intercalated with bands rich in orthoclase cryptoperthite (anorthoclase) and quartz. Abundant garnet (almandine-pyrope), Fe-rich cordierite, dark blue-green tourmaline and prismatic sillimanite are developed along the interfaces of the biotitic and alaskitic layers. Biotite is, under the microscope, intensely pleochroic from "paprika-red" to almost colorless and is undoubtedly rich in Ti as well as Fe. Sillimanite and tourmaline lie in the foliation planes with their long axes parallel to the fold axes. Cordierite, not recognized when the 1962 NYSGA Guidebook was written, is abundant in parts of the outcrop and can be recognized in some places by its characteristic blue or purplish blue color imparted to hand specimens. Under the microscope, it shows both polysynthetic twinning and sector-zoning or twinning; alteration to fibrous pinite plus the twinning make it difficult to identify and it may be mistaken for altered plagioclase; characteristic yellow, bulls-eye halos are virtually absent. Thin sections cut across foliation planes show numerous square cross-sections of sillimanite needles enclosed in cordierite. The relatively Fe-rich nature of this cordierite, 100Fe/(Fe+Mg) = 25 is useful in limiting the pressure at which the high-temperature regional metamorphism occurred; it is 2-4 kbars with water vapor present but not necessarily saturating the pore spaces. This, plus the hypersthene and sillimanite-K-feldspar parageneses fix the parameters of regional metamorphism in this part of the Hudson Highlands at T = 700 - 800°C and P = 2 - 4 kbars.

A4: THE NYACK SECTION OF THE PALISADES: FACIES, CONTACTS AND LAVA DOMES
Jeffrey C. Steiner
Dept. of Earth and Planetary Sciences
The City College of New York
New York, NY 10031
INTRODUCTION
The Palisades is a large, internally layered tholeiite intrusion which is exposed for approximately fifty miles along the west side of the Hudson River (figure 1). This trip examines pigeonite and augite dolerite sites on an Upper Nyack to Valley Cottage, New York traverse (figure 2).
The data previously collected at these sites will be used to address the issue of identifying the number of magma pulses which produced these and related facies. Peripherally, the relationship of the internal layering to the pulses will also be explored.
The Palisades has widely been considered to have arisen from at least two magma pulses (Walker, 1969). These pulses were defined petrographically by Walker (1969) and may be synchronous with the First Watchung and Ladentown-Union Hill Basalts, respectively (Puffer, et al., 1982, and this volume). Recently, Shirley (1987) identified three to four poorly defined pulses, none of which were characterized petrographically. The pigeonite and augite dolerites of present interest document a pulse distinct from those identified by Shirley (1987), but petrographically similar to Walker's Pulse 1 at Haverstraw Quarry.

A4: THE NYACK SECTION OF THE PALISADES: FACIES, CONTACTS AND LAVA DOMES

STOP 1 NYACK BEACH STATE PARK - OLIVINE LAYER
The escarpment at the eastern edge of Nyack Beach State Park represents the western wall of an infilled stone quarry. On this rock face, at approximately 40 feet above the presently obscured basal contact, a subhorizontal "rotten" zone (first horizontal depression above tree line) can be observed. This zone presumably represents the last vestige of the olivine layer referred to by Walker (1969) It appears to fade northward of the present location.
A closeup view of this structure, which involves a certain risk due to the fractured nature of the rock infrastructure, reveals that the basal part of this horizon is undulose and uneven. It is marked by nodules of basalt enclosed in a weathered granular matrix. Samples of both material show that the composition of the matrix is nearly identical to the composition of early dolerite at thirty feet above the lower contact at Englewood Cliff (Steiner, in preparation). An analysis of one of the olivine bronzite nodules yield 10 percent MgO. This percentage is high for most facies of the Palisades, but substantially less than the 19 percent reported by Walker (1969) for the hyalosiderite facies.
Here, as elsewhere, it appears that cooling cracks are reasonably continuous through the rotten zone. This indicates that the rotten zone belongs to the same cooling unit as the overlying dolerite.

STOP 2 UPPER NYACK - LOWER CONTACT OF UPPER NYACK SECTION
The basal contact is well exposed along a small escarpment. Here, small, infilled cavities can be observed in the Triassic baked shales indicating that the sediments were not fully lithified at the time of intrusion, and the intrusion was relatively shallow.
A scramble up the escarpment for forty feet reveals small (3 cm) nodule-like protrusions in an otherwise uniform dolerite. These analyze to normal basalt (Steiner, in preparation). An olivine layer has yet to be discovered at this locality.
Backscatter electron imaging of the quench rock (figures 7 and 8) shows subophitic pyroxene and labradorite clusters surrounded partially by pools of interstitial glass. Titanomagnetite and minor plagioclase, sanidine, quartz, and residual glass populate the interstitial spaces (figures 7 and 8) .

STOP 3 UPPER NYACK - COARSE PIGEONITE DOLERITE
This coarse pigeonite facies is characterized by elongate (1 cm) augite laths with pigeonite cores or attached plates which runII parallel to the augite prisms (figure 3). This facies is substantially enriched in REE relative to the contact facies, and shows a slight positive Europium anomaly suggestive of plagioclase accumulation (figure 6).
Time permitting, proceed 25 yards south on Route 9W to intersect a well marked service trail which drops sharply down the east bank. Samples have been taken from approximately 30 yards down the trail to the summit of Hook Mountain. From Hook Mountain, the tabular form of the Palisades is visible against the southern skyline. At Piermont, the topography changes dramatically in apparent response to a stepwise increase in the angle of westerly dip of the Palisades. Haverstraw Quarry is visible to the north. The rolling hills of the Triassic basin are framed by the Hudson Highlands to the east.

STOP 4 VALLEY COTTAGE - COARSE AUGITE DOLERITE
The best developed porphyritic texture (figure 3) in coarse augite dolerite occurs in the landscaped outcrop at the corner of Christian Herald and Herald Court. Slabs of samples taken prior to landscaping will be shown. PLEASE DO NOT DEFACE THE PROPERTY. DO NOT VISIT WITHOUT THE PERMISSION OF THE OWNER.
The iron-enrichment of the Palisades at this stop is due to abundant titanomagnetite in the groundmass. Titanomagnetite is often dendritic, and is considered to occur as both a primary and a quench feature. There is little indication that the magnetite was emplaced secondarily via an aqueous vapor or solution. Chemically, and to a certain extent petrographically (mesostasis replaces micropegmatite) this facies appears to be equivalent to the late stage ferrodolerite, fayalite granophyre and other facies of Walker (1969), except that the iron enrichment is not accompanied by iron rich ferromagnesian minerals, such as ferroaugite or fayalite. Ferroaugite rims may occur, but the bulk clinopyroxene is clearly augite.
The REE patterns (figure 5 and 6) are consistent with the derivation of this facies from the pigeonite facies through crystal liquid fractionation.

STOP 5 VALLEY COTTAGE - WEATHERED COARSE AUGITE DOLERITE
This is one of the few localities not in someone's yard which shows weathered coarse augite dolerite. Other localities occur sporadically along Mountainview Road.

STOP 6 VALLEY COTTAGE - UPPER CONTACT RELATIONS
From the intersection of Route 303 and Lake Road, walk 20 yards north along the eastern side of Route 303 to examine the contact between diabase and sedimentary rock which dips northerly at about 45 degrees. The contact is very sharp at about 10 feet up from the sidewalk alongside the telephone pole. It is otherwise somewhat hard to observe the trend do to the tendency for the dolerite to reduce the iron in the sedimentary rock producing a black baked sandy shale.
As observed at Stop 2, the intrusive dolerite has vesiculated the sedimentary rock. At this stop the cavities are somewhat sharper and lack infilling. The baked zone buttresses the east-west trending slope which marks the position of the Palisades contact as it extends toward Rockland Lake.
The texture of the contact rocks is microporphyritic with augite microphenocrysts. Within five feet of the contact the texture is ophitic, and beginning perhaps fifteen feet south, occasional recrystallized patches of interstitial mesostasis appear (figure 9).
Proceeding South, the diabase appears to plunge beneath the sedimentary cover. About 0.5 miles north of Lake Road, the contact is rediscovered on the upper potions of the exposed slope which is inset 60 yards east of route 303. The dolerite dips roughly west at about 45 degrees underneath a veneer of backed shales. The intrusive contact is therefore complex, wending in a curvilinear fashion along its margin in the general form of poorly exposed coalesced domes or localized arches.
To see quarried rock of horizon 1 (Steiner, et al. 1989a,b) drive west on Lake Road 0.3 mi to the Valley Cottage Fire Station and park along the West edge of the lot. The large blocks along the stream bank contain pegmatite dolerite clusters with sprays of augite locally reaching 6 cm.

STOP 7 WEST NYACK - COARSE PIGEONITE DOLERITE, INTRUSIVE RELATIONS AND LAVA DOME
The suggestion of a domal configuration at many points along the western contact is strongly supported by the lava dome situated southwest of the main quarry buildings. This dome was well exposed in the Fall of 1988, but has since been partially buried by crushed quarry rock.
Several facies are transected when walking or driving to Stop 8. In particular, trondhjemitic and granophyric varieties of the coarse dolerites, ultramafic segregation veins (Steiner, in preparation) and secondary "flowers" of chalcocite against malachite ovals along fracture systems may be visible. Unfortunately, many of these features have been completely removed by the quarrying operation.

STOP 8 WEST NYACK QUARRY - COARSE PIGEONITE DOLERITE WITH PEGMATITIC DOLERITE (COARSE AUGITE DOLERITE) PODS
Along the south end of the westernmost wall at the second level from the top, a coarse intrusive facies (H1, Steiner, et al., 1989a,b) invades diabases comparable to those exposed at Stop 6 along a narrow 12" dike. The dike shows an approximately 1" gap through which the magma welled up into adjacent rocks creating a balloon-like profile. This dike apparently represents an offshoot of the major contact which runs subparallel to the intersecting north wall. Pegmatite dolerite, comparable in many respects to the coarse augite dolerite of Stops 4 and 5 characterizes the general zone separating the two lithologies.

STOP 9. (OPTIONAL) WEST NYACK -SECOND UPPER CONTACT AND REDUCED ZONE
Park and walk up slope to prominent outcrop.
Here, a dip slope of the Triassic arkose (fossil fish locality) which is visible below abuts the Palisades. Portions of the metamorphosed sedimentary rock form a veneer over and are partially crosscut by offshoots of the dolerite. The tendency for the reduction of iron is again visible in the sedimentary rock.

A5: STRATIGRAPHY AND SEDIMENTOLOGY OF MIDDLE AND UPPER SILURIAN ROCKS AND AN ENIGMATIC DIAMICTITE, SOUTHEASTERN NEW YORK.
ANTHONY R. PRAVE and MOSES L. ALCALA
Dept. of Earth and Planetary Sciences
The City College of New York
New York, NY 10031
JACK B. EPSTEIN
U.S. Geological Survey
Reston, VA 22092
During much of the Silurian Period, sedimentation patterns throughout the northern Appalachian Basin record west to northwest spreading of terrigenous and marginal marine clastics into a deeper water mud and carbonate basin (Cotter, 1988; Middleton, 1987). The clastics were derived from highlands uplifted during the Taconic orogeny in eastern Pennsylvania and southeastern New York. By the Late Silurian, active tectonism had ceased so that the (dis)equilibrium between sediment influx, basin subsidence and relative changes in sea level were the probable first-order variables controlling facies distribution.

A5: STRATIGRAPHY AND SEDIMENTOLOGY OF MIDDLE AND UPPER SILURIAN ROCKS AND AN ENIGMATIC DIAMICTITE, SOUTHEASTERN NEW YORK.

For the next 12 miles there are scattered outcrops of Martinsburg Fm.

Martinsburg-Shawangunk contact to left.

Excellent view of the Pocono Plateau
Parking area to right affords an excellent view of the Pocono Plateau; intermediate ridges are in the Middle Devonian Hamilton Group; Neversink Valley is floored by Upper Silurian - Lower Devonian rocks.

Middle Devonian Esopus Fm on right.

Ascent is on Wisconsinian till covering Upper Silurian - Lower Devonian rocks.

STOP 1A (PORT JERVIS AREA) BLOOMSBURG RED BEDS.
Epstein and Lyttle (1987) estimate that the Bloomsburg Red Beds is about 335 m thick near Port Jervis, NY. These strata can be traced continuously across New Jersey from Pennsylvania with little facies change. The Shawangunk tongue, which separates the main body of the Bloomsburg from the Bloomsburg tongue to the northeast, thins to a feather edge at this locality and is unmappable at a scale of 1:24000. For the sake of brevity, the description and interpretation of the Bloomsburg tongue will be given at this stop and at Stop 5 for the Shawangunk tongue. Alcala measured the section from the top of the Shawangunk Formation to the top of the Shawangunk tongue (Fig. 6). The Shawangunk tongue is only 5 m thick. It is described in detail at Stops 5 and 6B. The Bloomsburg between those two units is 65 m thick and consists of ~5 fining upward cycles. Discontinuous pebbly lags occur above a flat to scoured erosive base which is overlain by fine to coarse quartzose sandstones and lithic wackes. These in turn grade upward into reddish or grayish fine sandstones and siltstones generally overlain by blocky red mudstones. Thin, discontinuous stringers of coarser sandstones are common in these finer clastics.
The fine to coarse sandstones above the erosive base consist of several centimeters-to decimeters-thick cosets of trough cross-beds arranged in sigmoidal-and wedge-shaped bundles bounded by lateral accretion surfaces. The cosets generally thin upward. Planar cross-bedding and reactivation surfaces are present locally. Interference ripples are common on bed tops. The laterally continuous appearance of these sandstone beds is deceiving. They actually are broad. shallow channels that thin and pinch out into finer clastics (this will be seen from the top of the outcrop from a near normal-to-paleoflow view across I-84).
The overlying red and gray fine sandstones and siltstones contain abundant small-scale trough cross-bedding and flat lamination. Flaser and lenticular bedding, reactivation surfaces. interference ripples and burrows are common locally. The red mudstones generally contain desiccation cracks, horizontal and sub-vertical burrows and possible root traces. Calcrete zones and pedogenic slickensides are present in places.
These facies characteristics coupled with the paleocurrent data {Fig. 4) lead us to conclude that the Bloomsburg Red Beds record deposition in an intertidal environment. The broadly channeled, coarse sandstones were tidal channels that migrated through a finer detrital intertidal flat. Paleosols developed locally in a dry climate as indicated by the calcrete zones and dessication cracks. The thin, coarse sandstone stringers in the shales probably record exceptional tidal or storm events.
From the paleoflow data (Fig. 4), it is evident that ebb flows were dominant. The larger-scale trough cross-beds and lateral accretion surfaces make up the WNW-mode whereas the ESE-mode is more dependent on the presence of smaller bed forms. The lateral accretion surfaces and sigmoidal-shaped bundles indicate that tidal currents continuously mobilized the sandy substrate in a general WNW-ESE trend. These observations corresponds nicely with the pattern of tidal forcing one would expect given the Silurian paleogeographic reconstructions of Scotese et al. (1979) and Ziegler et al (1977) showing the Taconic highlands as a NE-trending belt that had an epeiric sea to the west (Fig. 7). We interpret the strong NNE mode on the rosette as representing a dominant lateral migration direction of the tidal channels due to the influence of a NE-flowing longshore current. Again this fits well with the paleoclimatic inferences of Ziegler et al. (1977) which indicate a southern, low-latitude high pressure system to the west of the Taconic highlands (Fig. 7): the counterclockwise circulation of surface winds associated with this high would force a NE-flowing longshore current along the western edge of the highlands. Thus, the paleoflow data indicate a dominant WNW ebb tide and a weaker ESE flood tide with a moderately influential NNE-flowing longshore current.
Unfortunately, the exposures are not quite good enough to determine spring-neap cycles. However, many of the coarser sandstones appear to have bundles of well-developed cosets and lesser-developed cosets which we have tentatively interpreted as full-vortex and slackening structures, respectively.

STOP 1B (PORT JERVIS AREA) TACONIC UNCONFORMITY BASAL SHAWANGUNK FORMATION.
The Shawangunk Formation is interpreted as recording a NW-flowing braided fluvial system draining the Taconic highlands (Yeakel, 1962; Smith, 1967; Epstein and Epstein, 1967, 1972) The facies and paleoflow data from this exposure (which is representative of the basal Shawangunk throughout the area) support that interpretation (at least for the basal part of the formation): thick-bedded, massive to large-scale trough cross-bedded, quartz-pebble conglomerate and coarse quartzite yielding uniquadrant paleocurrent rosettes (Fig. 8).
Here the Shawangunk rests unconformably on shale and graywacke of the Martinsburg Formation. The angular discordance is 5°. Along the contact is a 5 to 15 cm thick fault gouge containing angular Martinsburg fragments in a dark-yellowish orange clay matrix. Thus, this contact also represents a zone of tectonic displacement, the amount of which is not known. For a complete discussion of the relative effects of the Taconic and Alleghanian orogenies, see Epstein and Lyttle (1987).

Travel along south slope of Shawangunk Mtn
Travel along south slope of Shawangunk Mtn: note occasional Martinsburg outcrops.

STOP 2 (OTISVILLE). DIAMICTITE AT THE TACONIC UNCONFORMITY
This classic exposure of the Taconic unconformity along the railroad cut was visited on the 59th NYSGA Meeting (Epstein and Lyttle. 1987). This discussion is a summary of that visit.
The quarry across the road is in the Shawangunk Formation: it is about 2 km along strike from the type locality of the "Otisville Shale" of Swartz and Swartz (1931). As is evident, shale is meager. The "Otisville" is poorly-defined and should be discarded.
The shales and siltstones of the Martinsburg dip moderately to the northwest, whereas, above the unconformity, the quartz-pebble conglomerate of the Shawangunk dips 16° less. The basal surface of the Shawangunk is irregular and displays downward projecting mullions having a few centimeters of relief and spacings up to a few decimeters. Bed-parallel shearing is developed in places above the unconformity.
Along the contact is a diamictite as much as 30 cm thick with sharp, unconformable upper and lower contacts. Within the mud matrix are angular clasts of the Martinsburg (in places large parts of the Martinsburg appear to have been bodily incorporated into this zone) as well as angular to rounded "exotic" pebbles not present in the underlying bedrock: clean and pyritic quartz arenite, feldspathic and chloritic sandstone, cross-laminated feldspathic conglomeratic quartzite, siliceous and micaceous siltstone and red siltstone. Weathering rinds and pits are present on some of the pebbles and. along with the rounding, are evidence for subaerial transport and exposure prior to deposition. The above indicates that the diamictite is a product of mass wasting, possibly a colluvial gravel.
Also in this zone is a grayish gouge with slickensided quartz veins. This gouge and the mullions are typical of many of the Martinsburg-Shawangunk contacts in southeastern New York and indicate that the unconformity is a plane of movement, the displacement along which is not known.

Shawangunk Fm to right.

Shawangunk mine (Pb-Zn) on top of Shawangunk Mtn to right (Gray, 1961).

STOP 3 (BEAR HILL). LUNCH AND SHAWANGUNK FORMATION CROSS-BEDS.
These nearly flat-lying beds of the lower part of the Shawangunk Formation are near the crest of the Ellenville arch, a broad, open fold of Alleghanian age (Epstein and Lyttle. 1987). The basal 30 m of the formation are exposed here and consist primarily of quartz-pebble conglomerate and medium to pebbly quartzite composed of decimeter-scale cosets of trough cross-bedding. A well-developed joint pattern and numerous exposures of bedding surfaces afford an excellent opportunity to examine the relationship between quasi-3-D views and plan views of trough cross-bedding. These exposures can be used to discuss the 'proper' methods of obtaining paleoflow data from troughs.

Martinsburg Fm exposure to left.

STOP 4 (ELLENVILLE). SHALE-CHIP GRAVEL AT TACONIC UNCONFORMITY.
This exposure also was visited on the 59th NYSGA Meeting (Epstein and Lyttle, 1987) but it is a problematic exposure worthy of further puzzlement. Your opinions are encouraged.
The basal Shawangunk forms a slight overhang which affords a view of an in-place, shale-chip gravel developed beneath the unconformity. The shale-chip gravel is at least 60 cm thick and consists of very well sorted shale chips about 3 cm in length derived from the underlying Martinsburg (exposed about 6 m below this outcrop). It is crudely foliated parallel to bedding in the Shawangunk. This shale-chip gravel is similar to those of Pleistocene age derived from Paleozoic shales in many areas in Pennsylvania and New Jersey.
The excellent sorting suggests winnowing of the gravel during transport. This gravel and the diamictite observed at Stop 2 indicate that the Martinsburg surface, uplifted during the Taconic orogeny, was subaerially exposed and covered by colluvium and gravels. Much of this material was subsequently removed by erosion and the remnants were buried by the Shawangunk conglomerates. There are no known nearby sources for the exotic pebbles in the diamictite. As stated earlier, it is possible that they were derived from now-eroded Taconic nappes.

STOP 5 (ELLENVILLE). BLOOMSBURG AND SHAWANGUNK TONGUES.
This section was measured by Alcala. The Bloomsburg tongue is 48 m thick and consists of 37 fining upward cycles (Fig. 9). Seven meters of the Shawangunk tongue are exposed. The contact between the Shawangunk Fm and Bloomsburg tongue is gradational as is the contact between the two tongues.
The fining-upward cycles in the Bloomsburg tongue are similar to but contain more shale and mudstone than the Bloomsburg strata seen at Stop 1A. The sandstones forming the basal parts of cycles are the same. Quartz and lithic wackes that consist of sets and cosets of trough cross-strata are arranged in sigmoidalshaped bundles commonly bounded by lateral accretion surfaces. Given the same facies characteristics and paleoflow trends (Fig. 4), we interpret this section similarly. The dominant WNW-ESE bipolar rosettes indicate tidal flow. The data obtained from the larger bed forms again suggest a stonger ebb tide relative to the flood tide. The NNE mode indicates the continuing influence of northeast flowing longshore currents in forcing a preferred NNE migration direction of tidal channels. The finer clastics represent the intertidal flats. We interpret their greater proportion here as indicating deposition primarily in upper intertidal flat areas.
The first tabular-appearing quartz arenite bed marks of the Shawangunk tongue which consists predominantly of thick-bedded, fine to medium quartz arenites with minor shale and rare red shale. Shales occur as thin partings or layers up to 20 cm in thickness. Pebbly quartzite occurs in places (such a bed occurs about 4 m above the base here and at the section near Wurtsboro}. Bases of beds are erosive and flat to shallowly scoured and pebbly lags occur locally. Trough cross-bedding is common and occurs in sets and cosets 0.1 to 1 m thick. Planar cross-bedding and flat lamination occur locally; some of the finer sandstones contain small-scale cross-stratification. In all cases, laminations consist of alternating light-dark couplets. some of the foresets are defined by flat mud clasts. Interference ripples and, rarly, trails and burrows can be observed on some bed surfaces.
On the basis of the facies characteristics and paleocurrent data (Fig. 4), we interpret the Shawangunk tongue as a sub-tidal (and possible lower intertidal) sand body. The clustering of flow data in the western hemisphere of the rosettes (i.e. from 180° to 360°) indicates primarily offshore-directed transport, probably by strong ebb tides and possibly by rip and storm currents (note, however, that no hummocky or swaley cross-stratification has been observed to support a storm influence). The NNE mode indicates sediment transport by longshore currents. We interpret the 'clean' quartz arenitic character of theses sandstones as resulting from selective sorting by marine currents (the coarser, 'dirtier' sands were 'locked-up' in the tidal channels of the Bloomsburg). The presence of interference ripples and rare trace fossils further supports this interpretation.
Modern tidal flats display a progressive facies change. Upper intertidal areas are finer-grained, less and smaller channeled relative to the well-channeled, mid intertidal areas whereas sub-tidal zones are sandy (Klein, 1985). Examination of the measured sections (Figs. 6, 9, 11) indicates such a trend. The lower part of the Bloomsburg tongue contains more fines than does the uppermost part, i.e., deposition initially occurred in middle and upper areas of an intertidal environment with subsequent deposition in lower intertidal environments. As the transgressive event progressed, those deposits were covered by sandy subtidal deposits of the Shawangunk tongue.

STOP 6A (WURTSBORO). HIGH FALLS SHALE.
The High Falls Shale and correlative Poxono Island Formation are poorly exposed in this area. The nearest exposures to this locality are 34 km to the northeast near Accord, NY and about a similar distance to the southwest in New Jersey. The sections at Stop 6 (A & B) were measured by Alcala.
The section of the High Falls Shale is 10 m thick (Fig. 10), but it is incomplete (both contacts are covered). The High Falls consists of fine to medium quartzose sandstones with minor, laterally discontinuous greenish and reddish shale layers. Beds are composed of large scale trough cross-bedded sets and cosets as much as 80 cm thick. Lateral accretion surfaces and, less commonly, reactivation surfaces bound many of the sets. Planar cross-bedding, flat lamination. desiccation cracks. symmetrical ripples. and burrows and trails are moderately common. Bases of beds are flat but erosive and have local lags. Bed tops generally are mantled with interference ripples.
Examination of the paleocurrent rosettes (Fig. 10) clearly indicates that these are tidal deposits. The sedimentary structures and composition suggest lower intertidal to sub-tidal settings. The WNW-directed ebb tide was dominant. A less developed NE mode is once again interpreted as recording the influence of longshore currents. Curiously, these flows are rotated slightly clockwise relative to those of the Bloomsburg and Shawangunk tongues. We tentatively conclude that this probably indicates a slight reorientation of the paleostrandline to a more northeasterly direction. The NE-trend of wave ripple crests (Fig. 10) adds some credence to this speculation.

STOP 6B. (WURTSBORO). BLOOMSBURG AND SHAWANGUNK TONGUES.
The Bloomsburg and Shawangunk tongues are best exposed at this locality which is a normal-to-paleoflow view. Contacts between the "tongues" and the underlying Shawangunk Fm are gradational. The Bloomsburg tongue is 58 m thick and consists of 41 fining upward cycles (Fig. 11). The Shawangunk tongue is nearly complete (top contact is covered) and is 34 m in thickness. The facies here are similar to those observed at Stops lA and 5 except that they are thicker and have more paleosol and caliche layers. Thus, given the same facies and paleoflow trends (Fig. 4), the same interpretation is proposed: the Bloomsburg tongue is an intertidal deposit recording WNW-ESE ebb-flood tides and the Shawangunk tongue is a sub-tidal deposit. Both "tongues" were influenced by NNE-flowing longshore current.

Taconic unconformity and Martinsburg Fm
We will pass the Taconic unconformity and a long exposure of Martinsburg Fm described by Epstein and Lyttle (1987, p. C-71-73); under overpass is a slump structure to the right.

A6: EARTHQUAKE ACTIVITY IN THE GREATER NEW YORK CITY AREA: A FAULTFINDER'S GUIDE
ALAN L. KAFKA
Weston Observatory
Department of Geology and Geophysics
Boston College
Weston, MA 02193
MARGARET A. WINSLOW
Department of Earth and Planetary Sciences
City College of CUNY
New York, NY 10031
NOELL. BARSTOW
Rondout Associates, Inc.
Stone Ridge, NY 12484
INTRODUCTION: EARTHQUAKES IN THE NORTHEASTERN UNITED STATES
Although the area within a 100 km radius of New York City is clearly not as seismically active as most areas near plate boundaries, this area has had its share of moderate earthquake activity. For most earthquakes in the interior of the North American plate -- unlike the situation along plate boundaries -- it is not clear whether geologic faults mapped at the surface are the faults along which the earthquakes are occurring. The purpose of this field trip is to examine several geologic features in the greater New York City (NYC) area that might be related to earthquake activity. As we proceed, the following question will be addressed:
Are seismically active faults in the NYC area delineated by geological features that are observable at the earth's surface?
To understand earthquake phenomena in the NYC area, it is helpful to picture this area in the context of earthquake activity throughout the northeastern United States (NEUS). The NEUS has one of the longest records of reported earthquake activity in North America (Fig. 1). Earthquake activity was noticed in this region by early European settlers, and as the population density grew, an increasing number of earthquakes were reported. These earthquakes were usually minor, but sometimes not-so-minor, and occasionally even caused damage. Instrumental seismic monitoring in the NEUS began in the early 1900's, and routine reporting of instrumentally recorded earthquakes began in 1938 with the initiation of the Northeastern Seismic Association (Linehan and Leet, 1942). The first telemetered regional seismic network was operated in northern New England by Weston Observatory from 1962 to 1968, but it was not until the early 1970's that the present regional networks were established. The number of seismic stations in the NEUS steadily increased between 1970 and 1974. By 1975, a number of institutions operating seismic networks in the region formed a cooperative group known as the Northeastern United States Seismic Network (NEUSSN; Fig. 2). The data recorded by the NEUSSN has enhanced our ability to study the regional seismic activity. Analysis of these data provides insight into the possible causes of the earthquakes. RAMAPO FAULT FIELD TRIP
In this field trip, we will examine geologic features that might be related to earthquakes, and we will look for characteristics that might identify active and nonactive faults. Of several geomorphological features possibly associated with Quaternary age faulting in the NEUS, a few well-defined examples stand out in the NYC area (Figs. 6b and 7). These features appear to concentrate along the Ramapo Fault zone and the Hudson River valley. This field trip will visit several localities along the distinctive topographic lineament of the Ramapo fault system where geomorphic features suggest Quaternary displacements. These features include the following:
(1) Fault scarps (primary and secondary) along the length of the Ramapo Fault system.
(2) Different heights, numbers, and ages of river terraces across the Ramapo and Mahwah Rivers.
(3) Asymmetric valleys with river running against the faulted side of the valley. This suggests continued tilting of fault blocks (e.g. Ramapo and Mahwah Rivers).
(4) Narrow zones of unconsolidated fault gouge in soil along the Ramapo Fault.
(5) Repeated offset tributaries to the Ramapo river suggesting dextral shear.
(6) Migrated meander loops of the Ramapo River suggesting dextral shear.
Some features, such as offset tributaries, valleys, and asymmetric meanders are better observed on maps and aerial photos than on a field trip. Other tectonically controlled landforms, such as reversal of river drainage direction, changes in tilt of the Palisades sill, offsets in the sill, and abrupt changes in height of its basal contact, post-date the early Mesozoic, but cannot be proven to be Quaternary in age.
The field trip follows the trace of the Ramapo fault along the Ramapo River in NJ and the Mahwah River in NY. South of Suffern, the Ramapo fault system forms a well-defined linear feature. At Suffern, however, it appears to split into two or more splays beneath a floodplain. The lineament following the Mahwah River marks the boundary between the Hudson Highlands and the Newark Basin. The field trip will follow the Mahwah River to its headwaters, where the Ramapo fault appears to split or be truncated by the Willow Grove Fault. North of Willow Grove, a NE-trending fault can be followed to the Hudson River.
The presence of greater numbers and heights of river terraces on the west side of the Ramapo and Mahwah River valleys along the boundary between the Hudson Highlands and Newark Basin support uplift of the NW side of the valley, the Hudson Highlands, along the Ramapo fault. The regular spacing of the terraces down to the present river edge suggests episodic uplift during the Quaternary. The absence of terraces on the SE side of the river valleys appears to be independent of lithology. In other words, the river terraces on the NW side appear to be tectonic.
Several right-slip offsets of cross-strike (SE-flowing) tributaries occur where they empty into the Ramapo River. Two meanders of the Ramapo also appear to be structurally controlled. They also support Quaternary age right-slip motion.

A6: EARTHQUAKE ACTIVITY IN THE GREATER NEW YORK CITY AREA: A FAULTFINDER'S GUIDE

The Ramapo fault lies to the west between the Ramapo Mountains and the Ramapo River.

STOP 1. DEERHAVEN.
The topography rises toward the west in discrete steps forming several discontinuous terraces on the NW side of the Ramapo River valley. They are not matched on the SE side. The terraces have formed on both unconsolidated sediment and bedrock. Notice how the river flows to the NW side of the valley along most of its length, regardless of the topographic and bedrock changes on the SE side of the river. This suggests westward tilting of the valley toward the fault. Bear Swamp Brook cuts perpendicular to the structure (SE). Upstream its banks are unequal in height. The NE side appears to be higher, as is the case for several other cross-strike streams that cross the Ramapo fault trace.

The houses are built on a higher level.

Take a left at Deerhaven Road which follows a higher level.

Crystalline rocks
At fork make right and go up hill to discontinuous outcrops of crystalline rocks.

STOP 2. RAMAPO RESERVATION.
This stop involves a 30 minute round-trip hike. Follow a trail directly west to a bridge over the Ramapo River. Cross abandoned meander loops and marshy areas. Across the river is a large lake in a wide, flat flood plain. Begin to climb upward. Return to parking area. Exit to south only.

STOP 3. PAVILION ROAD.
Near the bottom of the hill are exposures of slickensided crystalline rock, one of the few outcrops of the Ramapo fault. These well-developed slickensides of unknown age suggest dip-slip movement with a minor right-slip component. Slickensided fault surface averages N 55-65°E, and dips 60-65°SE. Slickenlines pitch N 15°E, 55°SE.

Terrace levels
Route 202 runs along one terrace level above the Mahwah River that is not present on the eastern side. Some discontinuous, higher terrace levels can be seen on the west side of the road.

STOP 4. SKY MEADOW ROAD.
Proceed southwest and west down across the Mahwah River, driving toward the fault. The road climbs four well-developed levels between the river and the fault. Power lines on the mountain follow a natural bench for several kilometers. The river valley is terraced on the NW side, and is hummocky and irregular on the SE side. Drilling data near here suggest that a Triassic age vesicular lava flow, over 450 ft thick, accumulated near the border fault (Ratcliffe, 1980). Local relief at the edge of the basin at the time was approximately 450 feet (Ratcliffe, 1980).

This road runs parallel to the Ramapo fault.
The river valley narrows toward the north. The fault lies on the west side of the river valley. The topography rises on both sides of the road. However, on the east side, the landforms are hummocky and irregular, whereas on the west side of the river, there are distinct levels. The power lines follow one wide terrace.

STOP 5. CALL HOLLOW ROAD.
North of Ladentown and just south of Willow Grove on Call Hollow Road the ridge defining the eastern edge of the Hudson Highlands begins to turn north as you approach the Willow Grove Valley. The Mahwah River valley pinches out. The terrace along which the power lines have run also ends here. The lines cross the road to join a buried gas line that follows the NW-trending steep ridges and narrow valley. These features also truncate in Willow Grove valley. The gas line is buried in intensely fractured material. Triassic basalts on the W side of the road tilt SE.

STOP 6. WILLOW GROVE.
The Ramapo fault cannot be easily followed north of Willow Grove valley. The fault appears to trend more toward the north and to be offset about 4 km right laterally by an E-SE-trending fault that follows Minisceongo Creek through Willow Grove valley. The creek experiences several 90° bends near Willow Grove. The terrain to the north and west of Willow Grove consists of massive, rounded hills with short, non-linear valleys as is typical of the topography west of the Ramapo fault. An alternative suggestion is that Willow Grove valley could be a pull-apart developed between the diverging splays of the Ramapo and Theills faults. The saddle to the south consists of highly brecciated rock fragments.

STOP 7. THEILLS ROAD.
Here the best candidate for a continuation of the Ramapo fault is seen to follow the NE-trending section of Cedar Pond Brook. Terraces are seen only on the NW side of the stream valley. Once again it represents hilly Hudson Highlands juxtaposed next to Quaternary sediments. Notice here, too, that there are river terraces only on the NW side of the valley, and that the SE side is lower. Between Call Hollow Road and Theills Road is a possible horst block of Proterozoic gneiss (Ratcliffe, 1980). NE striking features in the area do not seem to offset lava flows, but discontinuous exposures do not allow confirmation of any post-Mesozoic movements, except for tilting of basaltic layers.

Cedar Flats Road and Matt Farm Road parallel the fault.

The road detours around Lake Bullowc.
The fault continues on NW side of the lake. The road then resumes its trend parallel to the possible fault.

STOP 8. MOTT FARM ROAD.
Slickensided surfaces, vertical to steeply dipping. Some slickensided surfaces dip steeply SW with slickenlines plunging 65-75°SW. Other surfaces dip steeply NW with slickenlines plunging 75-80°NE. Several fracture patterns are also evident.

Pass outcrop of brecciated rock with complex fracture patterns.

Natural terrace 2-3 meters high
At Tompkins Lake, follow road around toward north on natural terrace 2-3 meters high which is not present on the other side. Steep talus slope rises to west.

STOP 9. TOMPKINS LAKE.
View of terrace and former lake level.

STOP 10. TOMPKINS COVE QUARRY.
Cambro-Ordovician limestone beds with black chert interbeds and bedding-parallel stylolites trend N 10-20°E and dip 55-65°SE. Calcite-filled fractures cut the outcrop at N 20-30°E and dip 40-42°SW. The brittle features could be related to the Ramapo fault system. See Ratcliffe (1980) for further information. The quarry reveals eight fault zones that disrupt the structural continuity (Ratcliffe. 1980). The faults are identifiable as red or green zones of clay gouge and phyllonite, best seen on the south face of the quarry on all levels. These faults are SE-dipping reverse faults with left-or right-lateral offsets. Despite a youthful appearance, they are associated with folds (Ratcliffe, 1980) although they appear to have been reactivated to produce the clay gouge and slickensides. Ratcliffe suggests that the faults are pre-Mesozoic thrusts that were reactivated during the Triassic as normal and strike-slip faults.

Slickensided surfaces on a new outcrop
Slickensided surfaces on a new outcrop exposed on left at mile point 36.0. No stop here. As you proceed north on Route 9W, the Ramapo fault or Matt Farm Road fault runs close to the river. Route 9W is adjacent to or on the fault. Recent construction on Route 9W has revealed rich zones of slickensides, intensely fractured rock, and brecciated zones along this stretch of road.

STOP 11. JONES POINT.
Jones Point is built on a series of low terraces. Walk along the railroad bed toward the north. STAY OFF THE TRACKS! The fault also outcrops immediately behind the house. At the intersection of the road and the railroad tracks is a polished and grooved outcrop that marks the end of the crystalline rocks in this area. The steep, SE-facing fault surface is polished and has sub-horizontal glacial grooves. Small normal faults are seem on the exposure. Note that where the fault crosses the Hudson River, the river abruptly changes direction. The Indian Point power plant is located directly across the Hudson River to the east. The Canopus and Peekskill River valleys are visible from here.

View a possible older terrace and till remnant near a former chapel.

STOP 12. ABANDONED QUARRY.
The Ramapo fault cuts the south side of the hill. Between this site and the river are several low terraces. Note truncated (over-steepened) spurs here. Walking west over a wide flat area, there is a possible scarp and sag pond in the area not exploited by the former quarry. The small scarp is 1-1.5 meters high. The terrace is developed on stream cobbles of a former river level.

STOP 13. BEAR MOUNTAIN INN.
Refreshments, etc. The only scheduled rest stop.

STOP 14. PERKINS MEMORIAL DRIVE LOOKOUT.
The Ramapo fault crosses the Hudson River to enter the Peekskill Hollow or Canopus River valleys. Sharp bends in the Hudson River appear to be structurally controlled. Each linear river bend, when projected onshore in Westchester or Rockland County, is associated with an anomalously linear river valley that follows the same strike. Some examples include the Ramapo, Mahwah, Cedar Pond, Minisceongo, Canopus, Leeds Cove, and Peekskill Hollow valleys. The terrace on the NW side of the Peekskill river appears to be higher than on the east side. On a regional scale, the Hudson River is linear and trends N-S, except where crystalline rocks cross it. At least one of the NE-trending segments occurs where the Ramapo fault crosses the Hudson. Another SE jog occurs where the Willow Grove fault crosses the river. The trend of another sharp bend in the Hudson River toward the SE follows a lineament onshore into Westchester County along the linear Leeds Cove valley. This latter example suggests that the Ramapo fault offsets one kilometer right-laterally a possible fault beneath the Hudson River.

A7: ROCK SLOPE STABILITY: DESIGN, CONSTRUCTION AND REMEDIAL TREATMENT
CLAYTON L. BOLTON JR.
Engineering Geology Section
Soil Mechanics Bureau
New York State Department of Transportation
The design and construction of rock slopes with emphasis on stability began with the ability to drill and blast on an alignment whereby the final slope product was sound and durable and free of potential rock fall hazards. The first attempt at constructing a planar surface in rock was not for a highway but for construction of the sides of an intake channel for the "Niagara Power Project" in Niagara Falls, New York. The extra effort to develop a vertical planar surface for the intake channel was not to prevent potential rock falls but to establish a surface whereby the concrete channel wall liners could be built with a minimum overrun in concrete quantities. (Wnen one considers that the majority of the listed 38,846,000 cubic yards of excavation was in rock, and that several million square feet of rock face had to be prepared within a tolerance of six (6) inches, it is easy to see that quite a problem was presented to the various contractors to keep from overbreaking beyond the payline, or "B" line, as it was called, with conventional methods of drilling and blasting). The method for constructing the planar face was named "presplitting".
The results of "presplitting" in constructing the vertical planar rock wall were so good that it soon was considered to be worthy of utilization in establishing minimum maintenance, hazard free rock faces for highways, tunnels, building foundation excavations and other locations where rock stability is a major concern. New York State Department of Transportation incorporated "presplitting" in its EXCAVATION SPECIFICATIONS on August 27, 1970 by inclusion in Addenda 49 to the January 2, 1962 PUBLIC WORKS SPECIFICATIONS. Once the "presplitting" tool was in place for constructing a stable rock slope, the Engineering Geologist could then put his knowledge to work to establish a suitable rock slope design. This method of construction leading to proper design is another example of empirical knowledge's ability to make theory, fact.

A7: ROCK SLOPE STABILITY: DESIGN, CONSTRUCTION AND REMEDIAL TREATMENT

STOP 1: Slope has two (2) lifts.
A few bolts are in the top lift across from the west end of the parking area. There are more bolts near the location marker.

STOP 2: Slope has two (2) lifts.
A gabion wall is installed on the bench. There are numerous bolts in the upper face. A large dike cuts through the center of the face.

STOP 3: Between parking area and bridge
There are several areas between the the parking area and the Bridge which have rock catchment fences, rock bolts and/or buttresses.

STOP 4: Rock Slope Stabilization Project.
Slope is being trimmed to an inclination of 1 vertical on 1 horizontal.

STOP 5: Shoulder is being widened
Shoulder is being widened and rock slope is being trimmed to inclination of 2 vertical on 1 horizontal.

STOP 6: Vertical slopes
Vertical slopes on both sides of highway and in median. Massive wedge failure scar on south slope. (Fig. 2)

STOP 7: Mylonite zones, rock bolts
Several areas showing thick mylonite zones, rock bolts & wedge failures.

Catchment mesh

STOP 8: Rock slopes on both sides of highway.
There is a wide bench on the south side with a guard rail installed at the edge to act as a catchment.

A8: DEGLACIAL HISTORY AND ENVIRONMENTS OF THE UPPER WALLKILL VALLEY
G. GORDON CONNALLY
12 University Avenue
Buffalo, NY 14214
LES SIRKIN
Department of Earth Sciences
Adelphi University
Garden City, NY 11530
DONALD H. CADWELL
New York State Geological Survey
Room 3140
Albany, NY 12230
The glacial history of the Wallkill Valley of eastern New York first was described by Connally and Sirkin (1967) in the guidebook for the 39th annual meeting of NYSGA. Prior to their interest, the area had received scant attention. It was mentioned peripherally by Woodworth (1905) and discussed in abstract by Connally (1966). The only previous detailed work was a study of preglacial lakes reported by Adams (1934).
Before commencing the joint study, Connally and Sirkin established restrictive criteria for locating the bogs that have become the standard sections: 1) some aspect of the peat bog must be directly linked to some specific geomorphic event, 2) the bog must have a high, unbreached rim with exclusively internal drainage, and 3) a deep section must directly overlie glacial sediments. We refer to this strategy as an integrated approach and contrast it with the grab-sample approach of others.
Following the tenets of the integrated approach, Connally and Sirkin (1970) refined interpretations. They discussed the valley again in the context of the entire Hudson-Champlain Lobe (Connally and Sirkin, 1973) and then Connally (1983) and Connally and Sirkin (1986) discussed regional correlations.
In the summer of 1988, Connally completed a 25-year project, mapping the entire Wallkill Valley at a scale of 1:24,000. The 7.5' maps that cover the New York portion are on open file in the New York State Geological Survey in Albany, New York. NYSGS supported the later phases of this project, from 1983 through 1988, under the aegis of Don Cadwell. The maps are part of the data base for the Lower Hudson sheet of the Surficial Geologic Map of New York. During NYSGS sponsorship, new landforms have been recognized, new ideas have been generated in the field of glacial geology, and new interpretations have been applied to the Wallkill Valley.

A8: DEGLACIAL HISTORY AND ENVIRONMENTS OF THE UPPER WALLKILL VALLEY

Esker complex on left
Esker complex on left marking the Pellets Island Moraine in the Rutgers Creek valley

Dead ice sink on right
Dead ice sink on right; in-wash is mined for sand and gravel

Lake Fairchild/Lake Dyson lake bottom
Lake Fairchild/Lake Dyson lake bottom at left, now the Wallkill River floodplain

View of inversion ridge
The inversion ridge formerly identified as the "Sussex Moraine" is visible at 11:00 o'clock

STOP 1. INTERNAL STRUCTURE OF AN INVERSION RIDGE
NOTE! Permission to enter this property has been obtained for this trip ONLY! RAIA Industries, in Hamburg, New Jersey, probably will NOT grant permission to individuals.
Walk down the inversion ridge to the exposures in the active sand and gravel pit. This feature formerly was described as the "Sussex Moraine". What type of depositional environment can you infer from the sedimentary structures? What and where was the source for this sediment? Where was the glacier? In what condition was the ice?
As you travel to Stop 2, you will cross the upland drainage system that fed onto the ice to form this feature. Keep your eye peeled for this at mile 26.1.

The head of the inversion ridge drainage channel
Upland drainage system strewn with boulders to the right, dead ice and inversion ridges (then, stream channels in the ice) to the left.

Lake Fairchild/Lake Dyson lake bottom ahead, on left.

Pochuck Creek valley to right at 2:00 o'clock

Bridge across Pochuck Creek

Orange County muck-lands
Orange County muck-lands on both sides of the road for next 5 mi. This is the last remnant of Glacial Lakes Fairchild and Dyson.

A cluster of 5 drumlins forms "Big Island"

The Pellets Island Moraine crosses the Orange County muck-lands.

Drive up the distal slope of the Pellets Island Moraine

STOP 2. INTERNAL STRUCTURE OF THE PELLETS ISLAND MORAINE
NOTE! You must obtain permission from Gurda Gardens, Ltd. to enter this sand and gravel pit.
Walk into the sand pit on the west side of Cedar Swamp Road. This pit is about 5 km east of the type locality for the Pellets Island Moraine at Pellets Island. The old pit, visited in 1967, is badly slumped today. What type of depositional environment can you infer from the sedimentary structures? What and where was the source for the sediment? Where was the glacier? In what condition was the ice? How does this deposit contrast with that at Stop 1?

Bridge across Wallkill River

STOP 3. SMILEY FARM ESKER(?)
NOTE! DO NOT EVEN ASK! This popular stop was included on the 1967 trip. Since then, the Smiley's have been deluged with visitors - most of whom have not even asked permission. For many reasons, the Smiley's DO NOT WANT PEOPLE VISITING THEIR WORKING FARM. DO NOT EVEN BOTHER TO ASK PERMISSION! We have obtained permission for this trip only--and only because of our long association with the Smileys and with this stop.
Climb the hill on the east side of the dirt access road. Gather at the top of the hill, that is located about midway between the Pellets Island and Wallkill Moraines. See if you can come up with an explanation better than 1967's when the term "moulin kame" was bandied about.

LUNCH STOP. THOMAS BULL MEMORIAL PARK
This is the same lunch stop used in 1967. In May of 1967 it was so cold (it snowed in the Catskills) that Orange County thought we would cancel lunch and didn't even have the restrooms open for us. They are up the hill, on the left. If the weather is bad, we have reserved the picnic pavilion.

Wallkill Moraine
Wallkill Moraine visible on right from 1:00 o'clock to 4:00 o'clock.

Wallkill Moraine outwash apron
Wallkill Moraine outwash apron deposited at the edge of Glacial Lake Dyson at ±400 ft.

STOP 4. A ROADSIDE BOG
At this stop we will demonstrate the technique used in retrieving a core from a subsurface organic deposit. Although this site does not meet the restrictive criteria established by Connally and Sirkin, it is conveniently close to the road as a demonstration site. First we will probe the depth of the organic sediment and then retrieve a sequential core using a Davis Piston Corer. We also will discuss surface vegetation and the subsurface pollen stratigraphy of the Wallkill Valley.

Climb the distal slope of the Wallkill Moraine

"Inner" Wallkill Moraine
The road climbs the distal slope of the "inner" Wallkill Moraine

STOP 5. ESKER FEEDER FOR THE WALLKILL MORAINE
CAUTION! You are on the property of the Wallkill State Prison. If you do not obtain permission before visiting this pit you may expect a visit from one or more armed officers.
There is little exposure left at this site that is about 4 km north of the inner Wallkill Moraine. Look about for clasts that you can identify as white Shawangunk conglomerate or orthoquartzite sandstone. Take in the splendid view of the bare rock cliffs of Shawangunk conglomerate·--these are made fameous by mountain climbers from all over the northeast. Why are these cliffs so fresh? Why is the escarpment to the south covered by a blanket of talus? What is the source of the sediment for this huge esker that flanks the bottom land channel of the Wallkill River?
Look for evidence of Shawangunk conglomerate as you travel to Stop 6.

The foot of a feeder esker
The foot of a feeder esker appears on the left; the road parallels this esker up the hill to the base of the Shawangunk cliffs.

STOP 6. HEAD OF FEEDER ESKER AND VIEW OF SHAWANGUNK CLIFFS
This stop enables you to view the huge, block-sized clasts of Shawangunk conglomerate that were frozen in time as they were moving down into or onto the Woodfordian glacier. Evidently the hydraulic situation along the cliff was similar to a bergschrund on a cirque headwall. The plucking of these huge blocks resulted in a cleanly exposed rock face (or free face) once the glacier receded. Why don't you see these large blocks down in the valley? Why are these cliffs not covered with talus as are those to the south?
As you drive down into the valley, you will pass a second massive esker on your left. Look at the change in the size of the Shawangunk conglomerate clasts as you continue down to the valley floor.

B1: LATE PALEOZOIC DEFORMATION IN THE RESERVOIR FAULT ZONE AND GREEN POND OUTLIER, NEW JERSEY HIGHLANDS
L.D. MALIZZI AND A.E. GATES
Department of Geology
Rutgers University
Newark, New Jersey 07102
The New Jersey Highlands are part of the Precambrian Reading Prong which extends from Massachusetts to Pennsylvania (Fig. 1a). The field study area is in north-central New Jersey and contains the Reservoir Fault zone and Green Pond outlier.
The Reservoir Fault zone forms the boundary between the western side of the Paleozoic sedimentary rocks of the Green Pond outlier and Grenville gneisses of the New Jersey Highlands (Fig. 1b). The Paleozoic Green Pond outlier locally contains northwest-dipping reverse faults (Herman, 1987; Herman and Mitchell, 1989) and southeast-verging folds. These structures indicate southeast directed transport which is enigmatic with respect to the rest of the Appalachian foreland fold and thrust belt.
The major structure in the area is the northeast-striking Reservoir Fault zone. The fault zone is a high angle 100 m wide cataclasite and semi-brittle mylonite zone, which is composed predominantly of Grenville gneisses. Numerous theories have been presented for the deformational history of the Reservoir Fault zone including Mesozoic normal faulting (Lewis and Kummel, 1912; Ratcliffe, 1980), Proterozoic wrench faulting (Helenek, 1987), Alleghanian sinistral strike-slip faulting (Mitchell and Forsythe, 1988), and Alleghanian reverse faulting (Herman and Mitchell, 1989). Recent work by Malizzi and Gates (1989) indicates that the Reservoir Fault zone and Green Pond outlier form the east side of a positive flower structure that formed through Late Paleozoic dextral transpression with later sinistral strike-slip reactivation.

B1: LATE PALEOZOIC DEFORMATION IN THE RESERVOIR FAULT ZONE AND GREEN POND OUTLIER, NEW JERSEY HIGHLANDS

STOP 1. CONJUGATE REVERSE FAULTS IN THE DEVONIAN SKUNNEMUNK CONGLOMERATE
This is a typical exposure of the Devonian Skunnemunk conglomerate (Fig. lb). This conglomerate is a very coarse-grained quartz pebble conglomerate with a red-purple medium-grained sandstone matrix which is thin to very thick bedded. The conglomerate contains medium-grained red sandstone interbeds and is locally crossbedded.
The conglomerate exhibits bedding and cleavage with attitudes of N47E 48SE and N45E 90SE, respectively. This exposure contains conjugate reverse faults (Fig. 4b). The attitudes of the reverse faults are N57E 47SE and N52E 65NW. Movement sense is indicated by fiberous stepped quartz slickenfibers. The northwest-dipping reverse fault contains slickenfibers with an average attitude of N49E 73N. The reverse faults were produced by Late Paleozoic tranpression.
The exposure also contains sinistral en-echelon quartz vein arrays. The individual veins in the vein array are spaced 10 cm apart and reflect small scale displacement. The vein arrays were developed by a north-south compression which was probably produced by Mesozoic pre-rifting sinistral strike-slip movement.

STOP 2. STRIKE-SLIP AND REVERSE STRUCTURES IN THE PRECAMBRIAN PYROXENE-BIOTITE GRANITE GNEISS
This is a typical exposure of the granite gneisses that comprise the New Jersey Highlands (Fig. 1b). The rock is coarse-grained, brown to dark greenish-gray pyroxene-biotite granite to alkali-feldspar granite gneiss which is brown to dark greenish-gray. Major minerals include quartz, microcline, plagioclase, and clinopyroxene. Biotite, orthopyroxene, and hornblende are minor minerals. Accessory minerals include sphene, zircon, apatite, and magnetite. Epidote and chlorite are secondary vein-filling minerals.
The western side of the exposure consists of 3 m of green cataclasite composed of pyroxene-biotite granite gneiss. The cataclasite contains foliation that exhibits northeast-striking dextral drag. The zone of cataclasite also contains a minor brittle fault filled with fault breccia that is oriented N28E 80NW. Horizontal slickenfibers are present on the northeaststriking minor fault. In thin section, the cataclasite contains northeast-striking dextral pull-apart grains, minor northwest-striking sinistral faults, and offset grains exhibiting northeast-striking sinistral faulting. The cataclasite also contains both northwest-and northeast-dipping reverse faults. Movement sense is indicated by fibrous, stepped chlorite slickenfibers. The reverse faults average N53E 43NW and N47E 43SE.
The eastern side of the exposure consists of less deformed pyroxene-biotite granite gneiss. Sections of the eastern side of the exposure contain granite pegmatites but the majority of the exposure exhibits well developed gneissic foliation. The gneissic foliation is offset and dragged by minor northeaststriking dextral and sinistral faults and minor northwest-striking dextral and sinistral faults. The minor faults represent early and late shear joints (Figs 4a and 4c). Offsets are often difficult to trace because of local shifts in the stress field during deformation. In thin section, the granite gneiss exhibits a cataclastic texture with pull-apart grains and offset grains similar to the cataclasite.

STOP 3. REVERSE AND STRIKE-SLIP STRUCTURES IN THE DEVONIAN skunnemunk CONGLOMERATE
This stop contains exposures of the same formation described at STOP 1 (Fig. 1b). The conglomerate exhibits both reverse and strike-slip kinematic indicators. The hill at this stop is a large syncline that is known as Bearfort Mountain. The walk is relatively steep and not recommended for individuals who have physical limitations (use common sense).
At the bottom of the hill and along the side of the hill are sinistral en echelon quartz vein arrays. The quartz veins range between 1 to 15 cm wide and 10 to 40 cm long. The exposures along the hill also contain northwestand southeast-dipping reverse faults. The reverse faults are similar to those at STOP l. Movement sense is indicated by quartz and chlorite fibrous, stepped slickenfibers. The shallowing of reverse faults away from the Reservoir Fault zone is exhibited. Average orientations of the reverse faults are N53E 54SE and N47E 52NW.
A small-scale keystone structure bounded by conjugate reverse faults (Fig. 4b) is located at the top of the hill. Reverse movement sense is indicated by slickenfibers and by offset quartz pebbles and quartz veins. Average orientations of the reverse faults are N52E 65NW and N47E 48SE. The acute angle between the conjugate reverse faults indicate a west-northwest to eastsoutheast maximum compression. This exposure also contains the late cross-cleavage produced by sinistral reactivation of the Reservoir Fault zone with an average orientation of N81E 89SE.

STOP 4. CATACLASITE IN THE GRENVILLE GNEISS AND TYPE II S-C MYLONITE IN THE SILURIAN GREEN POND CONGLOMERATE WITHIN THE RESERVOIR FAULT ZONE
Directly to the right of the parking area is a 15 m vertical face of cataclasite (Fig. 1b). The cataclasite is composed of pyroxene granite to alkali-feldspar granite gneiss. The pyroxene granite gneiss contains microcline, quartz, plagioclase, and clinopyroxene. Minor minerals include hornblende, orthopyroxene, and biotite. The gneiss also contains accessory sphene, apatite, magnetite, and zircon with secondary chlorite and epidote. The pyroxene granite gneiss is cut by granitic pegmatites. The pegmatites are coarse-grained and contain quartz, plagioclase, and microcline and are highly radioactive. A minor mineral is biotite and zircon is an accessory mineral. Secondary minerals include epidote, hematite, and monazite.
The northeast-striking foliation in the cataclasite exhibits dextral drag. In thin section, the cataclasite contains offset quartz and plagioclase grains, kinked plagioclase grains, and pull-apart textures in microcline grains (Fig. 3a). All of the microstructural features indicate northeast-striking dextral shearing. The dextral kinematic indicators are offset by later sinistral movement.
500 m south along the escarpment of cataclasite is a Type II S-C mylonite in the Green Pond conglomerate. The Green Pond conglomerate is a medium-grained quartz pebble conglomerate with a medium-grained sandy matrix and silica cement. The conglomerate contains thin interlayers of crossbedded sandstone. The shear zones in the conglomerate are not very extensive. The sheared conglomerate contains a semi-brittle mylonite with well defined C-planes subparallel to bedding and poorly defined S-planes (Fig. 2a). Northeast-striking dextral drag is exhibited by quartz ribbons along C-planes. In thin section, the sheared Green Pond conglomerate contains -Type porphyroclasts, conjugate deformation bands and lamellae (Fig. 2b), and shear bands. All of the microstructural features indicate northeast-striking dextral shearing.
2012: This stop is 0.4 miles from the last pull off, not 4.1 miles, but fits the rest of the data...

B2: THE STRATIGRAPHIC RELEVANCE AND ARCHAEOLOGICAL POTENTIAL OF THE CHERT BEARING CARBONATES WITHIN THE KITTATINNY SUPERGROUP
PHILIP C. LA PORTA
Queens College and Department of Earth and Environmental Sciences
C.U.N.Y.
All of the formations to be visited on this field trip are Cambro-Ordovician in age and were deposited in very shallow waters (shelf settings) (Figure 1). A few of the formations contain shaley members but are almost entirely composed of dolomites and lesser amounts of limestone.
The Cambrian formations are remarkably persistent both laterally and vertically and this leads to extensive facies continuities, covering distances as great at 50 to 100 miles (Read, 1985). The Lower Ordovician formations (capped by the Knox Unconfonnity; Sloss, 1963) have a more heterogeneous character, still with the same lateral persistence, but with considerably greater variations in facies composition.
The Cambrian cherts appear to be facies-controlled (porous oolitic layers, sandy layers, etc.) except for the top of the Allentown Formation. The upper Allentown appears to be a surface of unconformity, but is not marked by deep incisions, just shallow channel cuts. The zone of chertification follows this surface and occurs as a series of complex rubble zones, and silicification along joints.
The cherts within the Rickenbach Formation (Lower Ordovician) are facies controlled and are widely persistent fanning a distinct marker horizon. The lower member exhibits an intrastratal breccia, but there is no evidence of an associated unconformity. The Epler Formation contains chert which is facies-controlled, but the most obvious varieties of chert are associated with paleokarst features. Some of the paleokarst features were filled by argillite which has also suffered later silicification. The Epler Formation is overlain by the Ontelaunee, a fossiliferous carbonate, a good portion of which has been strongly dolomitized. Chert is ubiquitous to both members of the Ontelaunee Formation and the Harmonyvale (uppermost member) is strongly cut by erosion features. This eroision surface is very variable and in some places has incised all the way down into the Rickenbach Formation.
The great variety and volume of chert extant within the chert-bearing carbonates of the Kittatinny Supergroup has been known for some time (Markewicz, 1967). The use of chert beds as stratigraphic marker horizons or key beds was first implemented in this region by Markewicz (1967) and Markewicz and Dalton (1973). Their formation and member level subdivision (Fig. 1) will be used for the field trip. The chert appears to be restricted to specific units within members of the formations of the Kittatinny Supergroup. The chert-bearing facies are laterally persistent for substantial distances. (The host rock for the silica are often highly porous beds, unconformities and paleokarst fractures.) An extension of the chert stratigraphy has been the discovery, over the last two decades, of more than 200 small and large sites of prehistoric mining operations sites.
The chert stratigraphy is the focus of this field trip and has been specifically designed to also aid the archaeologist conducting provenance studies in the field.

B2: THE STRATIGRAPHIC RELEVANCE AND ARCHAEOLOGICAL POTENTIAL OF THE CHERT BEARING CARBONATES WITHIN THE KITTATINNY SUPERGROUP

STOP 1. PALEOKARST FEATURES AT DeKAY'S HAMLET.
The paleokarst features at DeKay's Hamlet are unique for several reasons. They are clearly visible on the Wawayanda topographic atlas sheet, and are outlined in Fig (3}. The single hole-like depressions are of great areal extent, and the likelihood of discovering more in the vicinity is very good. The infilling within the inverted depressions contains much more chert than is seen at other locations. The feature rests on the Upper member of the Allentown Formation. To the writer's knowledge, this represents the deepest penetration of the Knox-Beekmantown erosional event in this area.
Along Price Road, the Allentown Formation is poorly exposed and is visible as thickly bedded coarse grained blue dolomite with thin beds and wisps of black oolite chert. Capping the Upper Allentown is a chert sequence of variable thickness. Sawed slabs of chert from the Price Road outcrops have yielded both algal rich beds and slabs with a structureless form. The chert sequence capping the Allentown at DeKay's Hamlet may represent algal beds in some locations, while in others the chert may represent a silcrete (Khalaf, 1988}. Above this zone is the extensive rubble of the paleokarst feature. Chert clasts can be very large and the refitting of chert clasts, blocks, and beds within a single block of karst infilling dolomite is easily accomplished. The infilling between chert clasts and individual dolomite blocks is a very coarse grained buff dolomite.
The chert clasts appear to be representative of the Hope Member and the Crooked Swamp Dolomite Facies of the Rickenbach Formation. At a nearby location along Owen's Station Rd. in Wantage Township, a similar chert breccia contains the preserved remains of cystoid-like organisms.
In the surrounding valley, the outcrops of the Upper Member include a distinct intra-stratal breccia zone with siliceous infilling. The chert horizons may represent the remains of a vast doline system which penetrates the Allentown Formation and creates a plexus of breccia zones which may be genetically related to the vast subaerial feature being viewed at the first stop. This unique chert breccia and silicified infilling has not been encountered elsewhere in the valley, and recent field evidence suggests that in the Vernon Valley, the karstification may proceed down as far as the Limeport Member of the Allentown Formation. Virtually all of the farm fields in DeKay's Hamlet show exposed beds of the breccia and the laminated infilling described under the Upper Allentown Member. Similar laminated chert beds and brecciated zones are visible in the Big Springs Member of the Epler Formation but these do not bear the color characteristics of the Upper Allentown Member chert. Therefore it is logical to assume that the process of silicification and brecciation is similar in both cases.
The paleokarst feature appears to have provided quantities of chert to Archaic as well as Woodland Age groups of hunter-gatherers. The workshops and screes have a different character about them because the quarrying process is unlike other locations. Here, large angular chert clasts are worked free from the surrounding dolomite, instead of mining a single continuous bed of chert as at other locations. In addition, the archived collections from the area exhibit diagnostic projectile points whose overall morphologies are statistically different from culturally similar stone tool inventories from neighboring areas. This measurable difference in physical attributes may be linked to the individual artisan or to the physical properties and limitations of the chert. The writer feels the latter reason may be more important at this location.
The breccia zones described above crop out on nearby farm fields and all have been quarried for the intra-stratal breccias and silicious infillings.

STOP 2. THE PALEOKARST AT THE BEAVER RUN.
The traverse at Beaver Run begins in the Hope Member of the Rickenbach Formation, with the Leithsville and Allentown Formations behind you to the east (Fig. 4). Prominent within the Hope Member is a silicified intra-formational conglomerate, in which both rounded clasts as well as matrix have been silicified. This intra-formational conglomerate is also visible along the eastern edge of the Haven's Estate, and in the Richter Estate (see Fig. 4). The beds are inclined to the northwest and the intra-formational conglomerate has been interpreted by some to represent the base of an extensive paleokarst system. The paleokarst is first visible within the Branchville Member of the Epler Formation, where the dolomite is brecciated and re-cemented in-situ. When this occurs within the Big Springs and Lafayette Members of the Epler Formation, the solution crevices contain a laminated green argillic infilling, which occasionally bears euhedral pyrite. Farther up-section the topographically inverted karst infilling is visible to your right. The feature stands 180 feet in elevation above the roadside, and is prominent at the 700 ft. contour interval in Fig. 4. The eastern half of the feature is developed within the Epler Formation. The dislodged and overturned masses of dolomite in the eastern portion of the feature are derived frcxn the Big Springs and Lafayette Members.
Midway through the paleokarst feature, large blocks of chert bearing dolomite, derived from the Beaver Run Member are visible as a stack of disorientated re-cemented blocks. The slabs may represent the collapsed roof structure of the karst system. The paleokarst is best developed within the Lafayette Member. The evidence for karstification within the Epler Formation is visible along strike to the north into the Blair Estate Traverse and the Haven's Island #1 traverse, far greater than 6,000 ft. The feature continues to the south across Beaver Run Road more than 4,000 ft. to the Richter Prehistoric Chert Quarry along the Phillips Traverse (see Fig. 7).
The thickened Ontelaunee Formation section may be the result of faulting (see Fig. 4), and as you continue up-section, you encounter the Jacksonburg Formation (Ojb). From this point, proceed north along strike in the Beaver Run member. Here, along the western edge of the traverse are a splay of intrusive dikes, thought to be upper-Lower Ordovician. Approximately 1,000 feet north, along strike and southeast of the Dagmar Dale Estate, is a prehistoric chert quarry developed within the Beaver Run Member. This quarry and associated scree is typical of those developed within the Beaver Run Member. There is an enormous quantity of broken chert, all representing the earliest stages of the lithic reduction process.
If time and interest exist, traverse downsection on the Blair Estate, of which you are presently on the western edge. Visible will be paleokarst within the Epler formation, chert quarries within the chert breccia zones of the Lower member of the Rickenbach Formation, and a series of convex upwards silicified algal beds present in the Upper Allentown Formation. The algal structures are present on the Haven's Estate and elsewhere within the Hamburg Quadrangle and may represent a distinct marker horizon.

STOP 3. THE PREHISTORIC QUARRIES AT BEAVER RUN CREEK.
The traverse begins on the south side of Pond School Road 700 ft. east of the road, in the Lower member of the Rickenbach Formation. The rubble zone marking the unconformity is at the top of the Upper Allentown Member. The chert breccia of the Lower Rickenbach is present here (Fig. 5). Above the chert breccia is the lower chert horizon of the Hope Member. Proceed up section into the Branchvile member of the Epler Formation. Visible from this point is yet another type of paleokarst infilling. Here are large cemented masses of a very coarse grained dolomite. Throughout the dolomite are clasts of lavender and blue chert. The clasts represent the broken and disrupted chert bearing beds of all three members of the Epler Formation. Two hundred feet to the south is a series of round-like structures which represent a prehistoric quarry operation within the Branchville Member. The chert present is translucent white·with lavender brecciated masses. This breccia is tightly welded., and the quarry is represented by buried tailings.
Across School Pond Road to the west 300 feet is the prehistoric quarry at Beaver Run. This is an excellent location because the quarry has been acted upon by erosion and the prehistoric workings are visible.
The traverse begins 200 feet upsection in the Beaver Run member of the Ontelaunee Formation. A massive black chert zone is present in the Beaver Run member. Evidence of the reduction process is to be found at the quarry face. Many of the quartzite boulders and cobbles lying in the rubble represent the broken remains of discarded hammer and anvil stones. Approximately 75 feet above the thick chert sequence is the base of the Harmonyvale Member. There are a great number of conical depressions along strike in the many chert beds of the Harmonyvale Member. This pattern may represent the differential weathering of the solution cleavage within the Harmonyvale Member.
Both members of the Ontelaunee Formation are included in this quarry, and the workings and prospects extend an area of 450 feet by 300 feet. In this quarry, the Harmonyvale Member appears to be the preferred ore, as most of the deeper prospects are developed within this member. There is more archaeological visibility within the lower Beaver Run member, than in the Harmonyvale Member. The Beaver Run chert is usually conspicuous on the landscape, forming benches and topographic high areas. The prehistoric workings are usually extensive and the quarries can be developed continuously along strike. The tough ash-gray dolomite of the Harmonyvale Member, oftentimes caps the crests of hillsides and is covered by vegetation. Prehistoric workings within the Harmonyvale member are much less visible to the observer. Usually, a single light blue chert bed will be worked continuously along strike for several hundred feet as at this 1ocation. Because Harmonyvale chert occurs as thinner beds, the conical pits and workings along strike exhibit less visibility. Chert beds within the Beaver Run member can attain thicknesses of 8 or 10 feet, which render the quarries conspicuous. The writer feels that when both members are present in one quarry complex, the Beaver Run Member may be a second choice of lesser grade ore. The more highly sought after ore is the light blue chert of the Hannonyvale Member. This seems to be substantiated through the examination of archived collections.
Great quantities of quartzite hammerstones are present at this site. One large pounding stone or anvil near the Beaver Run member weighs more than 100 pounds. A collection of very diagnostic hammerstones was made at this quarry. These are always fashioned from quartzite, perfectly round and flat along their top sides, much like a wheel. Many instruments of this kind have been collected as well as hammerstones which appear to approach this diagnostic form. The hammerstones in the quarry represent the continuum of mining instruments, from expedient tools to instruments which are midway or at some stage of refinement towards being diagnostic. The final stage of processing appears to be represented by the spherical form with the flattened edges, or achieving the ideal pre-determined form.
Most of the quarry workings represent the initial reduction process. Chert from the quarry is found as unprepared cores, prepared cores, and diagnostic tools throughout the valley. It appears that much of the reduction process took place away from the quarry site.

STOP 4. THE HARMONYVALE TRAVERSE.
The Harmonyvale traverse begins at the base of the Branchville member of the Epler Formation (Fig. 6). The ravine to your east is occupied by the Hope member of the Rickenbach Formation, and the eastern edge of the summit is occupied by the Crooked Swamp Facies. Present is the sugary blue dolomite, which has a sulfurous odor on freshly broken surfaces, clots of varied-colored black and blue mottled chert, and silicified algal structures.
Proceeding up-section, the base of the Branchville member exhibits discontinuous black chert beds, up to 8 or 10 inches thick. Small chert outcrop quarries are present within this horizon. Up-section and to the south, one encounters the white chert of the Branchville member. The outcrops are littered with prehistoric workshop debitage and 30-40 small outcrop quarries exist along strike to the south in this member.
The Big Springs member crops out within the woodlot near the eastern shore of the pond. The lower unit contains a unique variety of chert which is maroon and white, and slabby. It represents a silicified shale unit which is stratigraphically similar to the maroon shales within the Upper Branchville member, at Haven's Island #4 Traverse. Above this unit are a series of jade green and white chert beds. The green chert beds may represent the silicified equivalent of the argillaceous karst infilling ubiquitous to the Big Springs Member. The white chert achieves an acme in form along this series of outcrops, where it is highly translucent, milky to waxy white to gray, highly lustrous, and occurs as both beds and clots. The laminated procelain-like gray chert is also present at these outcrops.
Close inspection will reveal prehistoric outcrop quarries, and a large quarry is buried under tailings at this location. The dolomite and chert blocks and rubble are part of the quarry tailings. Quartzite hammerstones, and chert debitage are abundant near the surface. Proceed along strike to the southeastern edge of the pond and back down-section 300 feet to the base of the Branchville Member, and the location of yet another prehistoric quarry. The principal ore here is the white chert and the porcelain-like chert. A small surface clearing has yielded hundreds of hammers tones and countless chert flakes. This series of quarries clearly illustrates the difficulty encountered when attempting to locate prehistoric chert mines. The ancient mining operations are usually buried in old tailings and fallen vegetation. This fact has also served to preserve their potential wealth of knowledge.
Now traverse up-section through the Big Springs and Lafayette members across the southern edge of the pond, and into the base of the Beaver Run member. Approximately 100 feet up-section occur the first series of dolomite and associated chert beds. The chert is vuggy, rugose and occurs in concentration as discontinuous swells which create topography to the south along strike. Each of these swells marks the location of very small chert outcrop quarries. Up-section is a second zone of chert which occurs as a series of beds which pinch and swell. The chert is homogeneous vitreous, and black, whereas the associated dolomite beds are thick and billowy. These chert beds are extensively quarried along the southwestern portion of the pond. The base of the steep ledge created by the resistant chert beds is covered with broken dolomite and chert beds, which have been pried from their ledges.
Transitional into the Harmonyvale Member is a dark and light blue mottled chert bed which is laterally continuous and eventually grades into a dolomite bed. The dolomite here is resistant, crosshatched, weathers to a white color and marks the lower Harmonyvale Member. Prehistoric mining activity is extensive here, but the precipitous climb and lush vegetation hinder close inspection.
Traverse along strike in the Beaver Run Member, passing the swells of rugose chert, and continue 1,500 feet to the 700 feet contour interval and a large scree developed along one bed of Harmonyvale chert. The workings in this light blue bed are continuous for 90 feet Below this scree is a 1arge quarry face developed in the upper unit of the Beaver Run Member. Inspect the proliferation of chert. To the immediate west lies the Jacksonburg Formation. Turn south. and traverse to the pond along strike in the Epler Formation. End of the Traverse.

STOP 5. THE RICHTER AND PHILLIPS ESTATES TRAVERSE.
The traverse begins in the rubble zone of the Upper Allentown member. Proceed up section through a thick chert breccia zone of the Lower Member of the Rickenbach Formation (Fig. 7). The ravine to your west is underlain by the Hope Member of the Rickenbach Formation and a distinct chert horizon is visible to the south along strike. The bedding dips to the northwest (see Fig. 7). Traverse through the open field which is underlain by the Crooked Swamp Facies, further south along strike. The step cliff overlooking the ice pond is composed of the Hope Member and Crooked Swamp Facies. The distinct chert horizon is visible in this ravine. The wall of the cliff face contains a partially silicified intra-formational conglomerate. Above this is a zone of sugary coarse grained blue dolomite containing wisps, beds and clots of a blue-gray translucent chert. This outcrop bears great resemblance to the Crooked Swamp Facies. The crest of this hill contains the Branchville member of the Epler Formation. The characteristic lavender and white brecciated chert zone is at the base of the member. Small prehistoric outcrop quarries are abundant along strike to the north. The ravine is occupied by the Lafayette Member and is much similar to the Lafayette Member ravine at Harmonyvale. You will cross this ravine to a hillside underlain by the Beaver Run Member of the Ontelaunee Formation. This is the Richter Estate.
The Beaver Run Member is covered by vegetation at this location. If you traverse north towards Beaver Run Road. you will cross over into the Harmonyvale Member, when the stratigraphic section thickens. Here are a number of small outcrop quarries and screes developed in the Harmonyvale Member. This light blue chert is very similar to the chert exposed in the quarry at the Phillips Estate, just to your west, and very similar to the chert at the Harmonyvale and the Beaver Run Quarries. The west facing slope is underlain by very fossiliferous Jacksonburg limestone. As you cross the Jacksonburg, you pass the location of a proposed fault, (see Fig. 7) and thereby re-enter the Beaver Run Member. Here the Beaver Run contains the upper chert-bearing unit, and a small prehistoric outcrop quarry and scree is present along the summit of the hill.
Passing westward, down the steep west-facing slope and into the Harmonyvale Member, you encounter a unique prehistoric quarry in the Harmonyvale Member. Vegetation-covered mounds of quarry tailings are present, along with the characteristic quartzite hammerstones. The unique feature of this quarry is what appears to be a rock-cut shaft which is about 10' x 10' and filled with tailings. A 6 inch thick light blue chert bed is inclined into the shaft at an inclination of 47° NW. The writer does not know how deep the shaft is or how extensive are the workings. As in the instance of the other quarries, all the workings are deeply buried and only a thin veneer of cultural debitage marks the locations of the ancient prospects. Erosion along steep slopes has exposed the workings and created a window into the past. Similar workings are present throughout this ravine which is to the north on the Phillips Estate. Just to your west is the Jacksonburg Formation repeated after the fault, and the Bushkill Member of the Martinsburg Formation (Omb) which comprises the western hillside and the termination of the traverse.

STOP 6. THE CHERT QUARRY ALONG THE PAULINS KILL.
The traverse along the Paulins Kill was suggested by Don Monteverde and Greg Herman of the New Jersey Geological Survey. They have noted large concentrations of chert within the Ontelaunee Formation. The prehistoric chert quarry on this traverse was located within the first day of research in the area.
The quarry is developed within the Beaver Run member of the Ontelaunee Formation, and has a length greater than 200 feet (Fig. 8). The chert beds pinch out to the north and south. To the writer's knowledge, the Harmonyvale Member is not present along this traverse. A distinct rubble zone occurs at the top of the section. and marks the incision of the Knox-Beekmantown Unconformity which removed the Harmonyvale Member at this location. The Jacksonburg Formation (Ojb) lies to our east under Paulins Kill Lake. The steep rise to your east is comprised of the Beaver Run Member and across Dove Island Road to your west lies the Epler and Richenbach Formations. If the stratigraphic formations contacts are interpreted correctly, the chert quarry is developed along the eastern 1imb of an antiform.
The series of black. and gray chert beds have been extensively worked. The gently inclined beds allowed easy access to the chert. This factor often determines to what degree the chert beds will be exploited. Tailings from the initial stages of reduction are abundant and this is one of the few quarries where structure and erosion are combined for excellent viewing. The chert beds are thick and homogeneous, with well-spaced fractures, creating a valuable ore of the black chert.

B3: ANCIENT LAND SURFACES IN AND AROUND THE GREEN POND OUTLIER, A DEVONIAN CORAL REEF, AND "TACONIAN ISLANDS" REVISITED.
ROBERT M. FINKS AND MICHAEL P. RAFFONI
Department of Geology, Queens College (CUNY)
Flushing,NY 11367
Some twenty years ago, at the 1968 NYSGA meeting, the senior author led a trip entitled "Taconian Islands and the Shores of Appalachia" (Finks, 1968). Having acquired a few new thoughts in the meantime, and a new generation of NYSGA members having come on the scene, it seems appropriate to revisit some of these localities on the way to a splendid Devonian coral reef studied by the junior author.
The sites visited are intended to stimulate further research rather than to present definitive answers. It is hoped that discussion will ensue, both on the trip and later. Much of the trip involves observation of fluvial bed-loads of various ages, and discussion of what they tell us.

B3: ANCIENT LAND SURFACES IN AND AROUND THE GREEN POND OUTLIER, A DEVONIAN CORAL REEF, AND "TACONIAN ISLANDS" REVISITED.

Anticline in Martinsburg Fm.
Anticline in Martinsburg Formation (Ordovician) on left. Zone 13 (possibly Zone 14) graptolites were collected here by Alejandro Vargas and identified by W.B.N. Berry (Vargas, 1976, p. 32 and fig. SA). Distal turbidites can be seen here.

Martinsburg Slate on both sides of the road.

Martinsburg Slate on both sides of the road again.

Klippe of Precambrian gneiss on right, forming hill.

Klippe of Precambrian gneiss on left
Klippe of Precambrian gneiss on left, in thrust contact with underlying Cambro-Ordovician dolomite. The thrust plane and accompanying fault breccias can be seen.

BONUS STOP. Museum Village Klippe
Walk into woods on left (south) side of road downhill toward NY 17, crossing the old, low stone wall left of the barbed wire. At highway level the thrust plane is exposed, dipping about 30° SE, with garnet-gneiss above and white-weathering dolomite below. Immediately above the fault plane you may collect samples of gneiss mylonite breccia, and immediately below it, tectonic breccia of dolomite.

Western border fault
The western border fault of the skunnemunk Outlier crosses approximately here, shown on the 1971 NY State Map as a small offset of the main fault at this point. (Fisher, Isachsen and Rickard, 1971.)

Bellvale Sandstone on left, dipping SE. (Mid-Devonian)

Axis of skunnemunk Syncline plunging NE.
Horizontal pebble beds of Bellvale Sandstone on left. Between here and .4 miles ahead is a 2,000-foot complete section of the Bellvale Sandstone (measured section in Finks, 1968) from submarine prodelta silts .4 miles ahead to subaerial piedmont conglomerates at here. It is a part of the Catskill Delta. The beds dip NW on the east limb of the skunnemunk Syncline.

Basal beds of Bellvale Sandstone, dipping steeply NW.

Ramapo Mountains ahead and to your left
Main mass of Ramapo Mountains (Hudson Highlands) are ahead (Precambrian of Reading Prong) and to your left as you swing south. You are in a valley on Cambro-Ordovician dolomitic limestones. This is also part of the Green Pond - skunnemunk Outlier, although the NY State Map has a structural discontinuity (normal fault) between these rocks and the Siluro-Devonian just passed through (Fisher, Isachsen and Rickard, 1971).

Outcrop of Cambro-Ordovician limestone on left.

Outcrop of Cambro-Ordovician limestone also on left.

Greenwood Furnace on left.
This smelter served the small magnetite mines in this vicinity during the 19th Century. The ore is from the Precambrian rocks.

Town of Tuxedo Park, where the Tuxedo jacket was invented.

Precambrian gneiss outcrop on left.

Crossing Ramapo Fault into Mesozoic Basin
Crossing Ramapo Fault into Mesozoic Basin, a rift-valley formed during the opening of the Atlantic Ocean. The Green Pond-skunnemunk Outlier has a similar structure and may be a Mesozoic basin in which no Mesozoic rocks were preserved. (Or a Siluro-Devonian extensional basin?)

Old stone house on right. Historic marker.

Good view of Ramapo fault-line scarp on right.

Crossing Orange Mountain Basalt (Lower Jurassic).

Outcrops of Orange Mountain Basalt on left.

Another basalt outcrop on left.

STOP 1. OAKLAND. JURASSIC FANGLOMERATE BENEATH THE PREAKNESS BASALT.
The most accessible outcrops are on the south side of the diner parking lot on the east side of US 202. Look for the boulders of vesicular basalt. Search for gneiss boulders. Some Paleozoic formations to look for are: white-to-buff-weathering Cambro-Ordovician dolomites, the purple with white quartz Green Pond Conglomerate, the red with white quartz and red quartzite Skunnemunk Conglomerate, the subgreywacke Bellvale Sandstone. Note their proportions.

Outcrop of Preakness Basalt on left.

This is Stop 2. Do not stop here but proceed to Noyias Road.

STOP 2. POMPTON LAKES. JURASSIC FANGLOMERATE BENEATH THE HOOK MOUNTAIN BASALT.
Park off road next to pumping station. Walk back to outcrop on east side of US 202. LOOK BOTH WAYS WHEN CROSSING ROUTE 202. YOU ARE ON A CURVE AND A HILL. VISIBILITY IS LIMITED. WALK FACING TRAFFIC AND STAY OFF THE ROADWAY.
Note the large boulder of Green Pond Conglomerate near the south end of the outcrop, and the many boulders of whitish-weathering Cambro-Ordovician dolomite. Note also the interbeds of finer sand and shale. How do the proportions of lithologies among the clasts compare with those of the preceding stop?

Outcrop of Hook Mountain Basalt on left.
The outcrop crosses the bed of the Ramapo River on the right, on top of which is a dam and waterfall.

Cross Ramapo River.

Crossing Wanaque River.

STOP 3. RIVERDALE. ANNSVILLE PHYLLITE (ORDOVICIAN) AND BED-LOAD OF THE PEQUANNOCK RIVER.
Descend carefully under the bridge and walk to the south side of the east abutment. There is also a path to this point from the south side of Hamburg Turnpike. CAREFUL CROSSING ROAD. The outcrop of the Annsville Phyllite is exposed here. PLEASE DO NOT HAMMER ON THIS RARE OUTCROP! THERE ARE PLENTY OF LOOSE PIECES LYING ABOUT. Another small outcrop lies upstream of the bridge in the channel and on the west bank.
Unless the river is in flood, a large sample of the Pequannock bed-load is exposed beneath and downstream of the bridge. Look for imbricated cobbles. See how many different Precambrian lithologies you can find. Green Pond Conglomerate cobbles are common. Can you find any Cambro-Ordovician dolomites? This river crosses the Green Pond outcrop about ten miles upstream, but much closer glacial moraines may be the source of most of the cobbles.

There is a quarry in Precambrian granite visible ahead.

Washington's Headquarters on left.

Crossing Ramapo Fault.
Road climbs hill on Precambrian with extensive cuts exposed in ramps for I-287. A gravel pit was formerly present to the left (south) in a delta built into Glacial Lake Passaic. Moraines on left about a half mile ahead.

Outcrops of Precambrian on right, Pequannock River valley on left.

Kanouse Mountain ahead, made of Green Pond Conglomerate on Precambrian.

You are paralleling Kanouse Mountain.

Bend in road. Hill of Precambrian ahead.

STOP 4. GOULD QUARRY.
PRECAMBRIAN GNEISS, HARDYSTON SANDSTONE AND LEITHSVILLE DOLOMITE (LOWER CAMBRIAN) , BASAL GREEN POND CONGLOMERATE (SILURIAN) IN KARSTIC POCKETS.
Outcrops at entrance to the road are Precambrian gneiss. Continue uphill on this road to the SW. Where the road bends to the left (south) continue straight ahead into the woods. You will soon reach a small swale. The lower Hardyston Sandstone underlies this swale. As you face SW, the hill on your left is Precambrian gneiss and the low ridge on the right exposes ledges of the upper part of the Hardyston Sandstone and the base of the Leithsville (or Stissing) Dolomite dipping NW. Walcott (1893) reported the trilobite Olenellus from the same beds a mile or so north, proving their Lower Cambrian age (and for us, their position on the Laurentian Plate). Follow this ridge a short ways to its southern end, where there is a small depression and cross-valley in the ridge. In the depression, against the ledges to the left, is a small pocket of conglomerate in the basal Leithsville Dolomite. (It may be covered by leaves.) This is a karstic cavity filled with the Silurian Green Pond Conglomerate which has infiltrated from above. A thin red shale lines this pocket. Walk to the top of the Leithsville ridge at this point through the small notch and descend its west side. Immediately to the right you will see a small patch of conglomerate on top of the steeply northwestward dipping beds of the Leithsville Dolomite. If you examine the dip-slope below it you can see a narrow extension of this patch apparently filling a fissure in the Leithsville. This must have been the entrance for the gravel into the pocket represented by the patch. PLEASE DO NOT HAMM£R ON THIS RARE OUTCROP! IT IS THE ONLY RELIC OF THE KARSTIC INFILLING. PLEASE PRESERVE IT FOR POSTERITY. This outcrop was illustrated by Rodgers (1971, p. 1160, fig. 9B). In the valley to the west is a small outcrop of the Green Pond Conglomerate just west of a small brook. The main mass of Kanouse Mountain, composed of the conglomerate, lies beyond. If you have time, note the ruins of the old lime kiln, north of the quarry, with its partly melted walls of stone blocks. The Leithsville was quarried here for lime. This tree-filled hollow was once an active quarry. The geologic relations here are illustrated in Kümmel and Weller (1902, figure 1).

STOP 5. NEWFOUNDLAND. GREEN POND CONGLOMERATE (SILURIAN) AND PRECAMBRIAN GNEISS.
The parking area is a loop of old Route 23 and is the original width of the two-way road. Note the historical marker with original relics of local iron smelting. To the south of NJ 23 is Charlotteburg Reservoir. Copperas Mountain to its right (west) comprises the extension of the Green Pond outcrop on the south of the Pequannock watergap. Seen in the distance to the west-southwest, are the ridges of Green Pond Mountain and Browns Mountain, also composed of Green Pond Conglomerate on Precambrian, repeated by folding and faulting.
The nearest ledges north of the parking area show well the steep westward dip and the fining-upward cycles in the Lower Conglomerate Member of the Green Pond Formation. Look for colored chert clasts (red, green, black) in the conglomerate layers. Many show weathering rinds. Follow the base of the cliff uphill to the east (right). A short distance up is a good place to see the cross-bedding. Note the consistent westward dip of the cross-laminations, indicating a westward current.
Continue upward along the base of the cliff and pick up a trail which heads uphill into the woods parallel to the base of the cliff but some distance from it. Keep on this trail in a northeastward direction. After several hundred feet you will come upon ledges of Precambrian gneiss. They are about 50 feet from the base of the cliff, the intervening area being strewn with large talus blocks of the conglomerate. The actual unconformity is not exposed here but it is clear that the conglomerate must rest directly on the gneiss.
When you return via the same trail you will see on the right (west) just above the ledges next to the parking area, beds of the higher non-conglomeratic part of the Green Pond Formation ("Upper Quartzite Member" of Finks, 1968). You can climb up to them if you have rubber-soled shoes or hiking boots (STAY AWAY FROM THE CLIFF EDGE TO THE LEFT) and observe the banded tongues (Liesegang rings) of hematite, showing former groundwater flow to the left (southwest) when the quartzite still had porosity.

Drag folds in Upper Quartzite Member of Green Pond Conglomerate.

Small outcrop of Longwood red shale (Upper Silurian) on right.

Type locality of the Kanouse Sandstone (Lower Devonian) in the village of Newfoundland to the right.

Outcrops of Precambrian.
We have just crossed the normal fault bounding the Green Pond-skunnemunk Outlier on the northwest. Oak Ridge Reservoir on left. The fault-line scarp bounds the reservoir on the west. This is called the Reservoir Fault (see Malizzi and Gates in this guidebook).

Franklin Lake on left. Source of the Wallkill River.

Outcrop of Cambro-Ordovician limestone on right.

Old Buckwheat Mine dump and Franklin Mineral Museum on right.
Old Buckwheat Mine dump (zinc mine in Precambrian Franklin Marble; type locality for Franklinite) and Franklin Mineral Museum on right.

Crossing Wallkill River.
This river flows northeast to join the Hudson River at Kingston, following the Great Valley on the Cambro-Ordovician outcrop belt. Water from Franklin Lake flows 75 miles northeast, then another 100 miles south before it reaches the sea.

Wildcat Road on left.
0.5 mile down this road is an exposure of the Precambrian-Lower Cambrian unconformity (described in Finks, 1968). The first archaeocyathids from New Jersey were found here in the basal Leithsville Dolomite by Frank Markiewicz on the 1968 NYSGA field trip.

Outcrop of Cambro-Ordovician Limestone on left.

Outcrops of Cambro-Ordovician limestone on left.

Outcrops of Martinsburg Slate on right.

Culver Lake on right.
Ahead is Kittatinny Mountain, held up by the Silurian Shawangunk Conglomerate.

Outcrop of New Scotland Limestone (Lower Devonian) on right.

STOP 6. COEYMANS LIMESTONE REEF LOWER DEVONIAN).
Park off road on right. Mile marker 1. Enter woods-trail ahead on left, opposite outcrop of pre-reef limestone on right.
Approach the reef by the trail which leads toward the high southeast cliff and attain the top by climbing the slope to the right (east) of it. Here you are at the supposed back-slope area dominated by massive Thamnopora. A good outcrop to start with, showing most of the coral species, is just west of the large glacial erratic boulder of shale. From here one may walk along the edge of the high cliff to the west and then north. The reef-ridge area of strong orientations, with dominant branching Thamnopora, solitary rugosa, and domal stromatoporoids, is best exposed at about halfway along the northwest face. (Compare Figures 5, 7, and 8.) From here one may walk south along a series of outcrops toward the highest part of the hill, seeing the back-reef lagoon facies and finally reaching the back-slope area at the top of the hill. From here one may walk northeast, past the old stone wall on the right (east) to a fine outcrop at the northeast tip of the reef, with silicified oriented branching Thamnopora well displayed, again part of the reef-ridge. (Compare Figure 10.) A walk back along the base of the northwest-facing cliff paralleling the reef-ridge will show some calcarenite channels in crosssection (or grooves of a spur-and-groove system) near the northeast end, some fine stromatoporoid colonies in vertical section about half-way along, and the pre-reef calcarenites at the southwest end. Note that the matrix of the main part of the reef is mostly micrite.

B4: THE WATCHUNG BASALTS OF NORTHERN NEW JERSEY
JOHN H. PUFFER
Geology Department
Rutgers University
Newark, New Jersey 07102
This field trip through the northern end of the Watchung Mountains of New Jersey will include six good exposures of quartz tholeiitic basalt. The Watchung basalt flows of the Mesozoic Newark Basin are exposed as three northeast/southwest trending ridges. The three basalt units dip to the west at about 15 degrees and are known as the Orange Mountain, Preakness, and Hook Mountain Basalts (Fig. 1).
The lower contact of the first flow unit of the Orange Mountain Basalt with the underlying Passaic Formation will be seen at Stop 2. The three flow units of the Orange Mountain Basalt are locally separated from each other by thin layers of sediment and comprise an aggregate thickness averaging 183 m (Faust, 1975). The upper flow is characteristically pillowed and amygdaloidal, whereas the lower two flows typically display well-developed columnar joints (lower colonnade and entablature).
Each of the three flow units of the Preakness Basalt are geochemically distinct, and each will be visited during the field trip. The massive, very coarse grained lower flow of the Preakness will be seen at Stop 3, the second flow together with a thin layer of sediment separating it from the first flow will be seen at Stop 4, and the second and third flows separated by another thin layer of sediment will be seen at Stop 5. The aggregate thickness of, the three Preakness flows averages 215 m (Olsen, 1980).
The lower contact of the Hook Mountain Basalt with the underlying Towaco Formation will be seen at Stop 6. The Hook Mountain Basalt extruded about 550,000 years after the extrusion of the Orange Mountain Basalt (Olsen and Fedosh, 1988) and consists of at least two flows with an aggregate thickness of 91 m (Faust, 1975).
The hydrous mineral assemblages that accumulated in the vesicles and vugs between pillows of Watchung Basalt, presumably mixtures of carbonates, clays and alteration products, have responded to low temperature burial metamorphic effects. The resulting zeolite facies assemblage includes some very well developed crystal aggregates of stilbite, heulandite, chabazite, and datolite typically precipitated with calcite, quartz, prehnite, and sulfides (principally chalcopyrite and chalcocite).

B4: THE WATCHUNG BASALTS OF NORTHERN NEW JERSEY

STOP 1. LADENTOWN BASALT
The closely-spaced curved cooling columns displayed by the Ladentown basalt along us 202 contrast with the thick massive columns typical of the Palisades sill that underlies the basalt and was probably its source of magma. The basalt exposed at this locality is fine grained, contains large plagioclase phenocrysts, and is slightly vesicular. Chemical analysis of the Ladentown Basalt (Puffer and others, 1982) compare closely with the fractionated interior (Walker's (1969) second magma pulse of the Palisades sill). The Ladentown Basalt, appears to have extruded onto sediments of the Passaic Formation, perhaps forced to the surface by the injection of a second magma pulse within the Palisades sill. This occurred before the Feltville Formation was deposited, and before the Preakness Basalt was extruded. A physical connection between the Ladentown flow and the western end of the Palisades sill at Mount Ivy is indicated by magnetic and gravity data (Kostsomitis, 1980; Kodama, 1983). However, this connection is not seen at the surface.
Good exposures of coarse boulder conglomerate are located another 0.4 mi. south along US 202. The coarse clast size of the sediment coincides with their close proximity to the western border fault in the valley running parallel to US 202. Note the distinct change in topography on the opposite side of the border fault where Precambrian gneisses are the dominant lithology.

Fanglomerate and Reading Prong
Coarse grained fanglomerate exposed on the left and the Precambrian Highlands of the Reading Prong exposed west of the Ramapo fault valley on the right.

STOP 2. PREAKNESS BASALT AT HIGH MOUNTAIN, NORTH HALEDON
High Mountain is the highest point (970ft; 296m.) in the Preakeness Mountain chain. The upper portion of the hiking or jeep trail to the top of High Mountain cuts through closely spaced columnar-jointed basalt typical of the entablature of the Preakness Basalt. At the top of the mountain is a beautiful alpine meadow that on a clear day affords a spectacular view of most of northern New Jersey. The basalt exposed in the meadow is very coarse-grained; it is typical of the interior of the first flow of the Preakness Basalt and resembles diabase.
The view to the southeast includes the New York City skyline in the background behind the ridge formed by the Palisades sill. (A copy of 1981 Paterson 7 1/2-minute Quadrangle is recommended). The city of Paterson is in the foreground where the Passaic River cuts through the First Watchung Mountain ridge formed by the westward dipping Orange Mountain Basalt. The New Street traprock quarries and Garret Mountain are clearly visible just north of Paterson. The view directly to the south includes the city of Newark in the distant background on the far side of the First Watchung Mountain, Montclair State College southeast of Paterson, and Paterson State College in the foreground. The view to the southwest includes the Precambrian New Jersey Highlands province west of the Ramapo Fault scarp in the background and the curved "inverted S" shaped Hook Mountain ridge formed by the Hook Mountain Basalt in the foreground.

STOP 3. ORANGE MOUNTAIN BASALT AT PASSAIC FALLS
An excellent exposure of Orange Mountain Basalt is located here in the park above Passaic Falls. Observe the columnar jointing in the basalt and some large convex upward, or half-moon vesicles that typically occur near flow-tops. Carefully climb into the narrow notch in the basalt eroded along the strike-slip fault for a closer inspection of the basalt. Most of the slickensides have been eroded away but a few still remain.
Cross the footbridge, or if blocked, walk down Spruce Street to the statue of Alexander Hamilton. At the exposure along the north edge of the parking lot near the statue of Alexander Hamilton, the lower contact of the Orange Mountain Basalt with the underlying Passaic Formation is seen. Southwest plunging pipe-amygdules and vesicles are exposed in the basalt near the contact. These vesicles occur entirely within the basalt above the basal contact. From the statue of Alexander Hamilton observe the vertical strike-slip fault planes through the lower flow unit of the Orange Mountain Basalt and the contact between the lower colonnade and the overlying entablature. The "S.U.M." over the door of the historic building near the river at the base of the view area stands for "Society of Useful Manufactures," an organization founded in 1789 to promote local trade.
From the falls, walk south along Spruce Street, cross McBride Avenue and continue one-half block to the Paterson Museum. Some of the best examples of the secondary minerals found in the Paterson area trap-rock quarries are on display at the museum.

STOP 4. PREAKNESS PILLOW BASALT, TOTOWA
The lower portion of a Preakness Mountain Basalt flow unit, the second of three, is exposed along the west side of Claremont Avenue. The base of the flow is a subaqueous flow lobe containing ellipsoidal pillows and pahoehoe toes. Secondary mineralization includes calcite, quartz, and minor heulandite in small stretched amygdules. The pillowed base of the flow rests on a thin layer of red siltstone exposed (depending on the amount of refuse present) at road level. The flow grades upward into massive columnar basalt. Further north on Claremont Avenue the upper part of the flow, in contrast to the bottom is not pillowed and contains large spherical amygdules mineralized with prehnite and pectolite.

STOP 5. UPPER (LOW-TI) FLOW OF PREAKNESS BASALT, NORTH CALDWELL
The middle and upper flows of the Preakness Basalt are exposed here together with a layer of red siltstone that was deposited between the two flows. The middle flow is well exposed along the banks of Green Pond (sample site P39, Fig. 1) and can be examined by carefully walking down the slope near the bridge. Be careful of the poison ivy. The middle flow is greatly enriched in incompatible elements compared to the upper high-Ti or HTO flow of the Preakness (Table 1).
The upper flow can be examined along the road-cut just south of the bridge (Sample site P40, Fig 1). It is exposed above the thin red silstone layer along the road. Good dinosaur footprints were found in this siltstone by Chris Laskovich. Columnar jointing is reasonably well displayed at this stop but both flows are other-wise quite massive with little evidence of secondary mineralization.

STOP 6. HOOK MOUNTAIN BASALT, ROSELAND
This Hook Mountain exposure displays columnar joints, but a well-defined Tomkeieff (1940) sequence is not apparent. An extensively altered volcano-clastic layer is exposed near the base of the Hook Mountain Basalt. In addition, some bleaching and evidence of low-grade thermal metamorphism is seen at the lower contact.
In contrast to the Orange Mountain (Stop 2) and Preakness (Stop 3) Basalts, the Hook Mountain Basalt is relatively enriched in amygdules and vesicles. Prehnite is abundant at this locality and is easily collected, particularly near the north end of the exposure.

B5: PLEISTOCENE GEOLOGY OF THE EASTERN, LOWER HUDSON VALLEY, NEW YORK
Les Sirkin
Department of Earth Sciences
Adelphi University
Garden City, NY 11530
Donald H. Cadwell
New York State Geological Survey
Room 3140
Albany, NY 12230
G. Gordon Connally
12 University Avenue
Buffalo, NY 14214
A preliminary understanding of the style of glacial retreat, in the eastern lower Hudson Valley, has been gained through mapping the surficial deposits between the Long Island-Staten Island end moraines and the Hudson Highlands. The present model of late Pleistocene glaciation for the region includes 1) a lobate ice front, 2) two distinct glaciations separated by a warm interval, and 3) final deglaciation with the sequential development of recessional moraines at some ice margins and extensive preglacial lake and valley fill deposits. This model is used in conjunction with field evidence to reconstruct the glacial history of the region. This field guide provides the basic framework for the glacial history and illustrates typical deposits and morphologic features. This article complements that of Connally, Sirkin, and Cadwell (this volume). For convenience, certain sections and descriptions are not repeated in both articles, but are crossreferenced.

Untitled Path

STOP 1. CROTON POINT PARK.
Walk westward along the beach about 0.5 mi. to exposures of till and clay beds. Discussion will center on the evidence for the Croton Moraine and the Croton Point Delta (see Figure 1 in text). Note the lithologies of the boulders.

STOP 2. PEEKSKILL HOLLOW CREEK: CLAY BEDS.
Park at the entrance to the new railroad station construction site. Walk northeastward to stream bed. Examination and discussion of clay beds exposed in the stream banks.
2012: The location of this stop is unclear. This Placemark is 0.5 miles south from the exit on route 9A. There is no bridge over a railroad, no new railroad station construction site, etc. A new station was opened in 1996, but the image from 1994 shows no construction yet where that went in. That would have been Northeast of Cruger, this point is south of Cruger, and the text indicates clay beds both northeast and south of Cruger.

STOP 3. PEEKSKILL HOLLOW CREEK: OUTWASH AND KAME DEPOSITS.
Walk along the northbound lane in the yard, bear right at fork between trailer home and concrete building, follow lane to gravel pit. This pit has been excavated into one of the many outwash and kame deposits in Peekskill Hollow. Some kames show ice contact features. At this site a kame delta has been overtopped by flood gravels suggesting a change from deltaic to high energy fluvial deposition.
2012: Became a golf course in 2004.

STOP 4. KAME DELTA.
Proceed into gravel pit. This is a large kame delta complex constructed by meltwater flow through the Highlands during development of the Shenandoah Moraine.

B6: A GEOLOGICAL CLIMB OF SCHUNEMUNK MOUNTAIN
WILLIAM J. TUCCI
Science Department
Valley Central High School
Montgomery, New York 12550
ROBERT KALIN
E.S.S. Department
Suffolk County Community College
Selden, New York 11784
GENERAL INTRODUCTION
This trip focuses on the area known as the Hudson Lowlands. To the east are found the Hudson Highlands, an area of Precambrian terrane of high relief which strikes northeast-southwest. The Catskill Mountains of Devonian age, with Silurian and Lower Devonian outcrops along their eastern front are found to the west. The Hudson Lowlands are an area of relatively low elevation which are underlain by Cambro-Ordovician calcarenites and argillites. It is part of a physiographic trough that extends from the St. Lawrence Valley south into Pennsylvania. This region has a maJor down-fold referred to as the Schunemunk Outlier. Schunemunk Mountain which is a portion of the central axial region has a height of 507 meters (1664 feet). The synclinal fold that makes up the axial region of the lowlands has flanks upon which older rocks are exposed in topographic highs. The central part is underlain by the youngest rocks which, being resistant sandstones and conglomerates, form ridge-like masses of northeast-southwest trend along the axis. (Kothe, 1960).
The word Schunemunk, pronounced Skun-uh-munk, is the Algonquin Native American name given to the mountain by its early inhabitants. The name means "excellent fire-place" in the Algonquin language and may be the result of the fact that this group at one time occupied a fortified site somewhere near the northern end of the mountain.
Schunemunk is a folded and faulted mountain, unlike the Catskills to the north and west which are erosional remnants of a plateau. Schunemunk is a complexly folded and faulted remnant of the Devonian. Despite the ravages of glaciers, erosion, mass wasting, and the frost action of the Hudson Valley, it stands out as one of the highest peaks in Orange County and one of the highest west of the Hudson River.

B6: A GEOLOGICAL CLIMB OF SCHUNEMUNK MOUNTAIN

Notice the use of the Schunemunk Conglomerate as a building material.

STOP 1: DEVONIAN FOSSILS
USE CAUTION HERE. THIS IS AN ACTIVE RAIL LINE. Park vehicles west of the tracks and proceed along the tracks about 110 meters (363 feet) to a worked outcrop of the Lower Devonian Esopus Formation (Lowe, 1958). This outcrop contains a wide variety of brachiopod and pelecypod fossils and (rare) trilobite fossils, as well as ripple marks in the tilted bedding planes. Note that Schunemunk Mountain is visible at N 15 E from this point.

Note glacial erratics and stratified sand and gravel deposits of glacial origin on the left of N.Y. Rte. 32.

Cemetery of the Highlands. Note the use of Schunemunk Conglomerate to build cemetery walls.

STOP 2: KAME TERRACE
Proceed north along the unsurfaced quarry road to a large outcrop of Precambrian schist and gneiss exposed by a quarrying operation. Glacial striae, grooves and chatter marks are common on the glacially polished bedrock. A fine view of Schunemunk Mountain can be observed to the southeast from the top of the exposure. This site is an abandoned sand and gravel quarry. The glacial deposits appear to have been formed as melt waters flowed from the edge of the ice and deposited their sedimentary load at the base of the Precambrian outcrop (Sorrentino, 1979). Much of the original formation has been removed by the quarrying operation. A variety of cobbles, pebbles and sand has been deposited against the bedrock of the Hudson Highlands. Return to the vehicles and continue north on N.Y. Rte. 32.

STOP 3: GROUND WATER
Follow the faint foot path through the cornfield. Observe the hillside to the south (left) of the dirt road for traces of surface water. Proceed about 160 to 170 meters (approx. 500 ft.) along the trail to a large oak tree bordering the woodland on the north. At this point the land to the south slopes upward and a small spring, which flows throughout the year will be observed emerging from the plowed field. About 100 meters (300 feet) further along the trail note a concentration of erratic boulders along the north side of the path. The boulders are part of a ground moraine, a deposit left by glaciers melting in place. Take note of the size and shape of the boulders.

STOP 4: RAPIDS OF BABY BROOK
Baby Brook is a youthful stream and is actively downcutting its bed. Several Important observations and definitions can be made at this stop: earth flows, gravity falls, solifluction, "V" shaped valleys, mass wasting, and hillside creep. Observe the large boulders in the stream bed and the curved boles of the trees along the sides of the stream.

STOP 5: WATERFALL OF BABY BROOK
Cross the railroad track and continue along the trail following the yellow markers. Walking time expended about 40 to 45 minutes. You will hear Baby Brook far below in a steep valley it has cut into the softer sandstone (Bellvale) below the resistant Schunemunk Conglomerate capstone.
Note the nature of the bedrock that is visible on the trail surface. This is part of the Hamilton Group which consists of Devonian sandstones. At about 50 minutes walking time a small side trail to the west will appear. This trail leads to the Baby Brook Falls. Here one can observe the Schunemunk Conglomerate as bedrock for the first time. The conglomerate acts as a resistant cap-rock which produced Baby Brook Falls. Beyond this point note the preponderance of Schunemunk Conglomerate (with its dark reddish brown matrix and milky quartz pebbles). Continue along the Jessup Trail (yellow markers).

STOP 6: APPROACHING THR SUMMIT OF SCHUNEMUNK
This site is said to be the site of an Algonquin Indian encampment. The connection between geology, topography, ecology, and the Algonquin's adaptation to these natural features can be explored. The participants should be encouraged to find the connection between these factors by placing themselves in their position and exploring their needs for food, shelter, wood, game, water, and protection from their enemies. Return to the Jessup Trail (yellow markers) and continue toward the summit. Along the way the many glacial features of the mountain should be noted: glacial polish, faceted pebbles of the Schunemunk conglomerate, chatter marks, plucking, and "white" carbonate erratics which have been transported from the north.

STOP 7: THE SUMMIT
From this elevation much of the topography of the region can be observed: the Catskills, the Shawangunks, and the Hudson Highlands. A question poses itself at this point: Why have Schunemunk and Woodcock Mountain, part of a nappe, (a remnant of a sheet like, allochthonous rock unit that has moved in a horizontal surface) remained?

STOP 8: THE MEGALITHS
The Megaliths are the result of faulting. These large blocks, originally fractured by faulting, have tumbled together to form "caves" as a result of glacial plucking and/or mass wasting. Snow can sometimes be found well into spring in these "caves". At this location many I features of faulting and jointing can be found. Joints, joint pairs, faults, slickensides (show direction of movement), frost heaving, and weathering can be identified.