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This is a compiled listing of all 185 field localities visited during our decade-long field trip series. For the time being, by scrolling to a locality, one can read a brief description of the geology found at that particular stop. References cited in this listing can be found in the On-The-Rocks Field Guides or can be searched from our long-standing NYC/Appalachian/Cordilleran Reference Database. The reference database is a 1.6 M Kb file (~600 p. text) so it will take a short while to load but we're sure you'll find it useful. We are still working on a searchable database and map-based text and figure linkages. Detailed geological descriptions of OTR field-trip localities "stops", including driving directions and commentary, figures, maps, and orientation data can be found in each of the individual On-The-Rocks Field Guides.

1. To understand the general geologic relationships of Long Island and the occurrence of ground water in various geologic units.

2. To be duly impressed by the evidence for the rapid westward growth of the west end of Fire Island as a result of inlet migration (average rate of 1 meter per week in the interval 1834-1940).

3. To become familiar with the composition of the beach sediment (including at least three populations of particles: a. well-sorted white medium sand; b. well-sorted dark-colored, esp. dark reddish, medium sand; and c. poorly sorted coarse brown sand, gravel, and shell debris.

4. To recognize the various parts of an ocean beach, including the shore-parallel ridges of sand (are they dunes?), berm, beach face (and/or beach scarp), and the three morphodynamic zones of an ocean beach: supratidal, intertidal, and subtidal.

5. To study the relationship between deposition of new layers of sediment and sediment surfaces, including both small-scale bed forms and large-scale depositional "slopes;" and to recognize plane, parallel strata and cross strata.

6. To understand how distinctive sequences of strata are formed by shifting of depositional slopes and the significance of prograding parallel to shore and of prograding normal to shore.

7. To understand the dynamic effects of processes such as waves and tides at modern sea level and to consider the long-term history of sea-level changes, as related both to movements of the lithosphere and to world-wide (eustatic) effects, particularly with respect to climate.

8. To realize how the effects of the operation of the geologic cycle through time create a geologic record of sediments and of sedimentary bedrock.

As this field trip was to a single locality, detailed descriptions are in the guidebook. [UTM grid coordinates of the beach located just beyond the picnic pavilion at Parking Field 3, the starting point of our westward traverse to the jetty, is 646.85E / 4498.05N, Bay Shore West quadrangle.]

1. To get to our third "new" van rental garage before they go out of business.

2. To enjoy the spectacular scenery of the southern Hudson Valley, New York, during its finest viewing season.

3. To examine the geologic evidence which proves that the mafic- and ultramafic rocks, including cumulates, of the Cortlandt Complex, are parts of a pluton intruded into the continental crust as magma and later cooled in place, and were not thrust upon it (as are ophiolitic sequences from the deep-sea floor).

4. To study the contact between the Inwood Marble and the stratigraphically overlying pelitic unit (lower schist of CM's revisions of the geology of the Manhattan schist, and/or Annsville Phyllite) and the contact metamorphic effects on both within the contact metamorphic aureole of the Cortlandt plutons and in xenoliths within the pluton.

5. To examine the effects on the bedrock surface of glaciers that flowed across the region at different times and from different directions, with particular emphasis on the crescentic marks made on the Proterozoic granitoid rocks of Bear Mountain.

6. To compare the composition of the clasts from near the base of the Newark Supergroup with the composition of bedrock now exposed nearby.

STOP 1 - Igneous flow layering in norite, Pluton V of Cortlandt Complex. [UTM Coordinates: 588.94E / 4568.78N, Peekskill quadrangle.]

Situated at the western edge of the Central Funnel of Balk (1927), we here examine northeast-dipping coarse- to medium-grained norite with an igneous flow lamination composed of plagioclase laths (reddish tint) and hypersthene (an orthopyroxene).

STOP 2 - Glaciated Inwood Marble and Manhattan Schist? [UTM Coordinates: 587.29E / 4567.44N, Peekskill quadrangle.]

Low outcrop on the north side of 11th Street of dolomitic- and calcitic Cambro-Ordovician marble exhibiting glacial grooves and scratches. On the south side of the street occurs marble plus phyllite also showing glacial striae and grooves. We think it's the Annsville Phyllite.

STOP 3 - Glaciated Manhattan-Inwood contact and the Cortlandt Complex, Franklin Delano Roosevelt Veterans Hospital. [UTM Coordinates: Traverse from 589.55E / 4565.1N to 589.1E / 4565.1N, Haverstraw quadrangle.]

Four areas of interest are here covered in a traverse. The traverse starts with a rounded knoll has been sculpted by glacial ice coming from two directions. We then examine the Sauk/Tippecanoe unconformity at the edge of the Hudson River, contact metamorphic effects in the Manhattan Schist (Unit Om), and the pegmatitic Cortlandt diorite.

STOP 4 - Poikilitic, flow-layered Cortlandt norite (Pluton V) with spectacular xenolith of contact-metamorphosed Inwood Marble. [UTM Coordinates: 589.65E / 4570.3N, Peekskill quadrangle.]

Orthopyroxene-bearing gabbro (norite) of Pluton V of the Cortlandt Complex here exhibits poikiloblasts of primary igneous kaersutitic amphibole ranging from 1-4 cm and averaging 2 cm in size. Within the norite occurs an elongate xenolith of tightly folded, contact metamorphosed Inwood (Wappinger equivalent) Marble.

STOP 5 - Perkins Observatory, crest of Bear Mountain: Proterozoic granitic gneiss with crescentic glacial gouges. [UTM Coordinates: 583.15E / 4573.5N, Popolopen Lake quadrangle.]

Here, we examine glacial grooves and crescentic gouges on rounded knolls of Proterozoic gneiss that have been sculpted by glaciers that flowed across the Hudson Highlands. The usual two directions are indicated: from NNE to SSW and from NW to SE.

STOP 6 - Stony Point Battlefield and west edge of Cortlandt intrusives (Optional). [UTM Coordinates: 585.62E / 4565.8N, Haverstraw quadrangle.]

At this stop we make three small traverses at Stony Point State Park; one south of along the railroad cut to see conglomerate of the Newark Basin, one along the railroad cut that exposes intrusive rocks of the Stony Point-Cortlandt Complex and, a walk through the famous Stony Point battleground.

1) To study the effects of extreme folding, faulting, and metamorphism of the Lower Paleozoic strata of New York City.

2) To examine lithologic variations in the three schist units of New York City formerly "lumped" together into the Manhattan Formation.

3) To examine the evidence for Cameron's Line and the St. Nicholas thrust.

4) To get up close and personal with mylonitic rocks.

5) To examine the effects of multiple glaciations.

6) To get in the groove, glacial-, that is!

7) To find sufficient restrooms to keep field trip participants happy, and,

8) To try to visit all of our planned stops (Fat Chance!)

STOP 1 - Hartland exposures near West 90^th to 91^st streets [UTM Coordinates: 586.22E / 4516.00N, Central Park quadrangle] and between West 82^nd to 85^th streets [UTM Coordinates: 585.95E / 4515.50N, Central Park quadrangle], Riverside Park, Manhattan.

The Hartland Formation or upper schist unit (C-Oh) crops out in Riverside Park from West 116th Street southward to West 75th Street. Exposures near West 90-91st Streets and from West 82-85 Streets are examined for metamorphic and glacial features.

STOP 2 - Middle schist unit (C-Om) exposed at West 165^th Street, Manhattan. [UTM Coordinates: 588.78E / 4521.44N, Central Park quadrangle.]

The middle schist unit (C-Om), is here exposed in a large outcrop west of Riverside Drive. We describe the structural and metamorphic geology of the rusty- to gray-weathering, coarse-grained biotite-muscovite-plagioclase-quartz-kyanite-sillimanite-garnet-tourmaline gneiss and schist with 2-15 cm interlayers of quartz-biotite-garnet-kyanite-sillimanite granofels. Several types of glacial features are also found here.

STOP 3 - Inwood Marble and Inwood-Manhattan contact, Isham and Inwood Hill Parks, Inwood section of Manhattan. [UTM Coordinates: 590.97E / 4524.72N, Central Park quadrangle and 590.66E / 4525.40N, Yonkers quadrangle, respectively.]

A few areas are examined in the traverse including facies of the Inwood Marble (C-Oi; originally called the Inwood Limestone by Merrill l890) in Isham Park. In entering Inwood Hill Park , the first prominent ridge is composed of kyanite gneiss and schist of the middle schist unit (C-Om). From there we examine a south-plunging F₃ antiform which exposes tan weathering, gray-white Inwood Marble.

The contact between the middle and lower schist units (the St. Nicholas thrust) is exposed in a 20 m zone from beneath the Henry Hudson Bridge abutment to river level. Directly beneath the bridge, where a dirt trail leads down to the river, a coarse-grained gray-white calcite marble with differentially eroded calc-silicate nodules is exposed at low tide. It is unknown whether the marble exposed at the low-tide mark is an interlayer in the lower schist unit (Om) or the Inwood Marble.

STOP 4 - St. Nicholas Park, west of St. Nicholas Avenue between West 129^th and West 141^st Streets. [UTM Coordinates centered on: 588.58E / 4518.74N, Central Park quadrangle.]

The St. Nicholas thrust here separates the middle schist unit from the Inwood Marble along the east edge of St. Nicholas Park. Excellent outcrops of the schist form the steep ridge of the park. The Inwood Marble is not exposed but, based on drill core data, underlies the lowland immediately east of the park.

STOP 5 - Mount Morris Park at West 122^nd Street and Fifth Avenue. [UTM Coordinates centered on: 589.15E / 4517.28N, Central Park quadrangle.]

Another traverse stop to examine the mylonitic contact of the middle schist unit (C-Om) from the Inwood Marble (C-Oi) and overlying lower schist unit (Om).

STOP 6 - Grand Concourse and the Cross Bronx Expressway, The Bronx. [UTM Coordinates: 591.70E / 4521.95N, Central Park quadrangle.]

An excellent exposure of the lower schist unit (Om) occurs west of the Grand Concourse in an overpass above the Cross Bronx Expressway (I-95). Massive Inwood Marble occurs in the roadcut forming the south wall of I-95 beneath the overpass. This locality, together with exposures described earlier in Inwood Hill Park (STOP 3) are interpreted as the autochthonous essentially in place) portions of the Manhattan Schist.

STOP 7 - St. Nicholas thrust and Cameron's Line, Cross Bronx Expressway, The Bronx. [UTM Coordinates: 592.94E / 4521.75N, Central Park quadrangle.]

Most of the Paleozoic rock units of the NYC area converge in and around Boro Hall and Crotona Parks in The Bronx according to our previous and ongoing research efforts. In these small parks, separated by I-95, marble, calc-schist, granofels, gneiss, and mica schist are all exposed from west to east in NE-striking, imbricated ductile-fault bounded tectonostratigraphic units.

1) To study the four major units that are in contact on Staten Island (from the top downward, Layer VII, Quaternary sediments; Layer VI, Coastal-plain strata; Layer V, Newark strata; and IIAE, Paleozoic deep-water metamorphosed strata, and included Staten Island serpentinite). We will start with the oldest unit and study progressively younger units.

2) To examine the serpentinite of Todt Hill in light of W. O. Crosby's (1914) idea that the serpentinite body which we see now has resulted from two notable modifications to the original rock, or protolith. As a second topic, we shall consider the possible age and origin of the associated breccia that contains clasts of both serpentinite (and relatated talc "schist") and red siltstones from the Newark Supergroup.

3) To examine the petrologic relationships in the Palisades intrusive sheet; to see the effects of high-temperature reaction between the mafic magma of the sill and a xenolith of Lockatong Argillite of the Newark Supergroup, which forms the country rock into which the "city rock" of the Palisades was intruded. The argillite that became engulfed in the mafic magma was not only heated, it actually was melted and the small bit of felsic magma that formed did not mix into the mafic magma, but cooled to form a felsic igneous rock unlike that formed by solidification of the mafic magma. We shall also study the morphologic relationships of the sill and discuss our new model designating Staten Island as a potential magma feeder for the Palisades intrusive sheet.

4) To see what happens to a beach when its supply of sand is cut off.

5) To study Pleistocene sediments (tills and outwash); soil-forming reactions; mineralogic immaturity; provenance of erratics; sedimentary characteristics of braided-stream deposits; state of decomposition/preservation of stones as basis for relative ages of units; hematite-cemented sandstones and /or conglomerates.

6) To find out the current status of the continuous interaction between the beach whose predominant direction of longshore transport is toward the SW and the mouth of a small stream.

7) To examine a stratigraphic succession (possibly not needing to be converted by us into an SSF) in which a much-decayed immature Quaternary braided-stream outwash deposit rests unconformably on mineralogically mature Upper Cretaceous sands and clays.

8) To examine the contrasting kinds of strata in the coastal-plain Cretaceous, notably the effects of marine transgression whereby open-shelf sediments came to overlie sediments deposited on an intertidal flat.

STOP 1 - The Staten Island serpentinite, local serpentinite-clast breccia, and the scarce mineral artinite, east side of Todt Hill. [UTM Coordinates: 576.35E / 4495.10N, The Narrows quadrangle.] Note: This exposure is on private property owned by the homeowners association consisting of local residents. Permission may or may not be available.

The glaciated knoll forming the south part of Emerson juts up from street level roughly 10 m and displays classic roche moutonée structure with a steep, plucked southern margin. This serpentinite is one of a large number of similar bodies scattered along the entire length of the deeply eroded core zone of the Appalachian mountain range. The oval-shaped Staten Island body is about 11 km long and about 5 km in maximum width and underlies a prominent northeast-trending ridge (locally called Todt Hill) through the center of Staten Island. The top of Todt Hill, altitude 540 feet, is the highest natural point in New York City.

The weathered knoll at Stop 1 is known to mineral collectors as the "Spring Street" locality, famed for its artinite, a hydrated alteration product of serpentinite. First described in 1902, the rare hydrated mineral artinite forms pure white- to transparent needle-like monoclinic crystals. After we have examined the serpentinite, we shall study the associated breccia, a small body of Lafayette Gravel, a post-Miocene formation on the Atlantic Coastal Plain.

STOP 2 - Palisades Intrusive Sheet in the old "Graniteville" quarry (a misnamed place; had a knowledgeable geologist given the name it might have been Doleriteville or even "Diabaseville". [UTM Coordinates: 571.60E / 4497.72N, Elizabeth quadrangle boundary.]

Walk south on trail for the locality studied by Benimoff and Sclar (1984). We shall go to the exact spot where their specimens came from and to study the effects of the interaction between the xenolith of argillite from the Lockatong Formation (formerly considered to be a small dike intruding the dolerite) and the mafic magma of the sill. Proof exists here that a chunk of the Lockatong Formation was not only internally altered by the heat from the surrounding magma, but that some of the Lockatong actually melted to form a felsic magma (magma rich in sodium/potassium feldspars). The rock which crystallized from this small amount of magma has been identified by Benimoff and Sclar (1984) as a trondhjemite.

Examination of the orientations- and marginal relationships of xenoliths in the Palisades intrusive sheet of New York and New Jersey suggests that one of the feeder areas for the intrusive sheet was in the vicinity of Graniteville, Staten Island because of the orientation of the xenolith and other features. By contrast to the gentle dips of all other xenoliths in the New York City are where xenoliths are parallel to the gently-dipping contact of the Palisades intrusive sheet, we contend that this unique vertical xenolith and the annular cooling fractures imply upward flow of the magma and thus proximity to the feeder channel.

The Pleistocene geology includes a place where red-brown till rests on the mafic bedrock along a sharp contact. On the surface of the bedrock in the quarry area, numerous ice-sculpted features are present. These include shallow trough-like grooves, striae, and crescentic marks. Crossing sets of features eroded by the ice on the mafic bedrock confirm the effects of at least two glaciers.

STOP 3 - Great Kills (Oakwood Beach) Park - Modern beach rapidly advancing landward by marine erosion. [UTM Coordinates: 574.15E / 4488.30N, The Narrows quadrangle.]

The Oakwood Beach is undergoing rapid erosion that has intensified during the last 14 years. In 1989, the year of our first trip to this area, the main bathhouse and building that is the office for the Park Police were in great jeopardy. A scarp, 2 to 3 meters high, had formed by the undercutting action at water level. This edge is an active slope subject to collapse and is marked by a snow/sand fence. Only a few years ago, the water's edge was 100 feet or more from this building and in April 1989 the water's edge was beneath the building (which is built on piles). By 1994, the building was condemned and by the late 1990's had collapsed.

This area is the only place on Staten Island underlain by a large body of outwash. Elsewhere, the Pleistocene deposits consist mainly of till. (This is the opposite of the relationships on Long Island, where outwash predominates and till is very localized.)

STOP 4 - Cliffs of deformed and overthrust Pleistocene and Cretaceous strata along Princes Bay. [UTM coordinates: 566.7E / 4484.2N, Arthur Kill quadrangle.]

The traverse at this stop includes a dig to expose several tills and interbedded outwash. In the face closest to the creek, the sequence from beach upward is red-brown till, red-brown outwash, and red-brown till, capped by what may be about a half meter of loess and the modern soil. Near the navigation tower, a considerable body of yellowish and whitish sands and light-colored clays [some layers containing bits of charcoal that Hollick (1906d) inferred came from ancient forest fires]. Included are firmly cemented quartz-rich sandstones and -conglomerates. Evidence found in the 1987 borings for the sewer line now recently completed along Hylan Boulevard (See Figures 38-41) show the same relationships as seen here: till at the surface, outwash below, and at still-greater depth, the presumably in-situ Cretaceous.

Our subsequent studies indicate that the Cretaceous surrounded by Pleistocene sediments is part of a gigantic glacial erratic that the ice tore loose and incorporated in the till (Sanders, Merguerian, and Okulewicz, 1995a, b). The geometry of folds bounding the Cretaceous slab indicate ice-shove deformation from NW to SE. Keep in mind that such Pleistocene thrusting took place under permafrost conditions when the Cretaceous sequence was undoubtedly still frozen! Here, the displaced Cretaceous is encased in outwash, which implies that the dislocation involved ice rafting of a frozen slab in a shallow stream.

STOP 5 - AKR Excavating Co., 4288 Arthur Kill Road, Kreischerville, Staten Island, about 1 mile N of Outerbridge Crossing. Red-brown till overlying decayed-pebble outwash, which rests on white, charcoal-bearing Cretaceous micaceous sands and gray clays. [UTM coordinates: 564.68E / 4487.42N, Arthur Kill quadrangle.]

At this stop we examine geologic relationships that are nowhere else exposed in the New York metropolitan area. These include Pleistocene outwash with spectacular examples of trough cross strata. Among the clasts in this outwash are abundant recycled sedimentary strata including many Newark red-brown siltstones, white quartz, and pieces of the Cretaceous ironstone sandstone and -conglomerate; and rare granitic rocks. The siltstones have been decomposed; they can be easily broken by hand and the feldspars in the granites have been completely decomposed. This decayed-pebble outwash overlies light gray- to white, cross-stratified sand containing lignitic plant debris and interbedded layers of light gray clay (Raritan Formation, Upper Cretaceous, the oldest exposed part of the coastal-plain succession).

STOP 6 - Park at Atlantic Highlands, New Jersey, with view into Lower New York Bay from a local park. [UTM Coordinates: 581.75E / 4474.31N, Sandy Hook quadrangle.]

Cross-stratified Cretaceous sands are exposed near the parking lot. Depending on the time situation, we may carry out a short dig to show the cross strata.

STOP 7 - Cretaceous sand pits behind new furniture store south of Matawan, New Jersey. [UTM Coordinates: 566.38E / 4470.91N, Keyport quadrangle.]

The upper parts of the face consist of marine sands, and the lower parts, of sediments from intertidal flats. In the coarse debris at the base of the marine strata are pebbles of ironstone conglomerate.

1) To study the minerals-, structure, and contact relationships of the Palisades Intrusive Sheet and the Lockatong Formation it has intruded.

2) To learn to distinguish an intrusive sheet from sheet of extrusive igneous rock solidified from an ancient lava flow.

3) To examine the evidence indicating that the paleoflow direction of the Palisades magma was from SW to NE and not from NW to SE.

4) To evaluate the evidence bearing on the state of lithification (or lack of it!) of the sandstones in the Lockatong Formation at the time the Palisades sheet was intruded and from this evidence to estimate the depth of intrusion.

5) To examine pillows--the products of the extrusion of hot lava under a cover of water.

6) To examine the characteristics of the Newark sedimentary strata and to notice the contrast between sediments deposited well away from the Ramapo fault at the northwest basin margin and those deposited close to this basin-marginal fault.

7) To study the composition of boulders in the basin-marginal rudites (general name for any coarse sediment composed chiefly of gravel-size debris, i. e., coarser than 2 mm).

8) To study the evidence for postdepositional faults.

STOP 1 - Palisades Intrusive Sheet, Olivine Zone, and Lockatong Formation at Fort Lee in Palisades Interstate Park, New Jersey branch. [UTM Coordinates: 587.58E / 4522.67N, Central Park quadrangle.]

Exposures along the Palisades Interstate Park access road beneath the George Washington Bridge feature the lower contact of the Palisades intrusive sheet above contact metamorphosed sedimentary rocks of the Lockatong Formation, former lake deposits in the lower part of the Newark Supergroup. The Palisades Intrusive Sheet is one of the world's premier examples of a large sheet of mafic intrusive igneous rock. The tilted- and eroded edge of the mafic rock is expressed in the landscape as the Palisades ridge along the west side of the Hudson River.

Immediately north of the George Washington Bridge is a spectacular exposure of the basal contact of the Palisades intrusive sheet. As originally diagrammed by Olson (1980c), and reexamined by your heroes, JES and CM, the Palisades is in discordant contact relationship with a deformed slab of the Lockatong Formation. Above the Lockatong, at the south end of the xenolith, note the chilled aphanitic (very fine) texture in the Palisades at the contact with the metamorphosed sedimentary rock. Microscopic vesicles occur in the chilled-contact basalt suggesting the presence of pore water in the sediments prior to intrusion. What is more, the sandy sediments are chaotic near the contact and have "intruded" upward into the Palisades as "sedimentary apophyses" and clastic dikes.

Ramping contacts and folds (Merguerian and Sanders, 1995a, b) indicate that paleoflow of the Palisades magma was from SW to NE, not from NW to SE as had been previously thought.

STOP 2 - Pillow basalt of Orange Mountain Formation ("First Watchung Basalt"). East side of McBride Avenue ~0.7 mile NE of intersection of Glover Avenue and McBride Avenue. [UTM Coordinates: 568.1E / 4528.9N, Paterson quadrangle.]

The McBride Avenue exposures are about in the middle of the outcrop belt of the Orange Mountain Formation here. Geologists exploring the sea floor in research submarines been photographed modern pillows forming where lava oozing out of a fissure reacts with the water in such a way that individual pillows are squeezed out, expand, and then separate. The large pillowed part of the Orange Mountain Formation is inferred to have resulted from the extrusion of lava on the bottom of a large lake.

STOP 3 - Lower contact of the Orange Mountain Formation ("First Watchung Basalt") and underlying sedimentary strata of the Passaic Formation. [UTM Coordinates: 569.00E / 4529.45N, Paterson quadrangle.]

In the low cuts in the parking lot one can see the contact between an overlying mafic extrusive igneous rock (Orange Mountain Formation) and a sedimentary rock (top of Passaic Formation). The contact is not a planar surface but displays considerable irregularity. The direction of in which a sheet of ancient lava flowed can be determined from cylindrical (="pipe") vesicles and -amygdales. Typically these are bent over in the direction toward which the lava flowed. According to Manspeizer (1980), pipe amgydales here are bent over toward the NE. (See Figure 38.) This is the opposite to the direction inferred for the paleoslope of the land surface (based on directions of flow of streams that deposited the cross strata). As a result, the lava here onlapped the regional paleoslope.

STOP 4 - The Great Falls of Paterson, Orange Mountain and Passaic formations. [UTM Coordinates: 568.9E / 4529.5N, hillside exposures E and N of stadium: 569.05E / 4529.75N for contact and 569.15E / 4529.85N for cliff face near dog pound, glacial erratic at 568.95E / 4529.65 N, Paterson quadrangle.]

The waterfall here drops about 75 feet (from the 120-ft contour at the lip to about 45 ft below). The Passaic River, flowing northeastward (more or less parallel to the strike of the tilted strata), pours into a fracture that trends N-S. The water tumbles over the lip on the rock forming the W side of the fracture, and then flows southward along the fracture, then makes a U-turn and continues flowing NE. No gorge has formed downstream, as has been eroded, for example, by the upstream retreat of the lip of Niagara Falls. In its flow along a fracture and absence of a gorge, Great Falls are a miniature version of the mighty Victoria Falls on the Zambezi River in southeastern Africa (Zambia/Zimbabwe).

This stop includes a walk northward beyond the falls to examine sandstones of the Passaic Formation and a large glacial erratic.

STOP 5 - Upper, glaciated contact of the Orange Mountain Formation ("First Watchung basalt") at Garrett Mountain Reservation. [UTM Coordinates of old house: 569.50E / 4577.75N, Paterson quadrangle, altitude: 500 feet.]

From the crest of the ridge enjoy the splendid view eastward toward Manhattan (atmospheric conditions permitting). Notice the two clusters of skyscrapers: at the Battery and in midtown Manhattan. This is a function of the depth of bedrock. Where the tall buildings have been built, solid bedrock is close to the surface. In between, where no tall buildings have been built, the depth to bedrock becomes several hundred feet.

Along the trail, look for vesicles in the basalt (we are near the top of a flow unit where vesicles are to be expected) and the glacial features. Present here are glacial grooves trending NE-SW, about parallel to the trend of Garrett Mountain, and a miniature roche moutonée structure.

STOP 6 - Upper- and lower contacts of the Hook Mountain Formation ("Third Watchung Basalt"). Near parking lot for shopping center at junction of Paterson-Hamburg Turnpike and Oakland Road, Pompton, in gap cut through Packanack Mountain by Ramapo River where U. S. 202 makes a 90-degree corner at the S end of Pompton Lake. [UTM Coordinates: 560.7E / 4537.8N, Pompton Plains quadrangle.]

The top of the Hook Mountain Formation is not visible at Stop 6, but on the basis of the amygdaloidal-vesicular structure of the igneous rock exposed at the edge of the parking lot one can infer that the top is not far away. The strata here strike NW and dip SW (a result of being on the SW limb of a transverse anticline whose axis strikes NW-SE). The highland about one mile due W of us is underlain by Proterozoic rocks of the Ramapo block; the Ramapo fault, the basin-marginal fault at the NW edge of the Newark basin, lies along the foot of the steep slope. The Ramapo River flows southwestward along the trace of the Ramapo fault.

The contact at the base of the Hook Mountain Formation is exposed in the cuts along the east side of US Route 202 (if we go there, be careful of the traffic). Notice the sequence of the columnar joints in the basalt and the coarse particles in the basin-marginal rudites of the underlying Towaco Formation.

STOP 7 - Basin-marginal rudites of Feltville Formation [sedimentary strata underlying the Preakness Formation ("Second Watchung basalt")]. Behind Oakland Diner. [UTM Coordinates: 562.2E / 4540.5N, Wanaque quadrangle.]

This locality is situated close to the Ramapo fault (buried beneath sediments of Ramapo River at foot of escarpment) near the NW end of Preakness Mountain, the type locality of the Preakness Formation ("Second Watchung Basalt"). The strike of the strata is NW-SE and the dip is to the SW. The sedimentary strata are from near the top of the Feltville Formation. What can be seen here, however, is an abundance of boulders of Cambro-Ordovician carbonates (mostly dolostones, not metamorphosed, and some limestones), vesicular basalt (presumably derived by eroding the Orange Mountain Formation), and Green Pond Conglomerate; and medium-rare boulders of Proterozoic gneiss (hold the steak sauce, please!). The predominance of pieces from the Paleozoic sedimentary formations indicates that the main body of the Proterozoic rocks forming the Ramapo block in today's landscape had not yet been exposed during the early part of the Jurassic Period when the Feltville Formation was being deposited.

At Oakland, we have ended a traverse downsection that began at the top of the Hook Mountain Basalt. We have cut through the entire Towaco Formation and the Preakness Formation and are in the topmost part of the Feltville Formation. Despite this change in stratigraphic position, the kind of rock (rudite) has remained about the same. Put another way this means that in localities within about a mile or so of the Ramapo fault, nearly all sedimentary formations consist of basin-marginal rudites. The total stratigraphic range of such rudites has not been determined, but it might come close to equaling the entire thickness of the Newark basin-filling strata. Why do you suppose that all the boulders are cut by fractures? (Are they really what they are cracked up to be?)

1) To examine the Hartland Formation of western Connecticut.

2) To locate and discuss glacial features.

3) To discuss the history of mining in western Connecticut.

4) To collect minerals and rocks from famous localities in western Connecticut.

5) Not to get bitten by ticks or mosquitos.

STOP 1 - Hartland Formation (upper member), Route 8 cuts, Torrington, Connecticut. [UTM Coordinates: 657.0E / 4624.9N, Torrington quadrangle.]

The outcrops forming the cliffs across from the commuter lot were originally described by Martin (1970) and subsequently detailed by Merguerian (1985). Here, 2-15 cm-scale very well-layered muscovite-biotite-plagioclase-quartz-(hornblende)-garnet) granofels occurs with interlayered schist of similar mineral composition. The abundance of muscovite in the rocks creates a lustrous sheen from foliation surfaces reflecting sunlight, a hallmark of aluminous Hartland lithologies. The pervasive interlayering of granofels and schist, high muscovite and plagioclase content, and presence of amphibolite suggests that protoliths of these rocks were volcaniclastic graywackes and interlayered shale with subordinate basalt flows.

STOP 2 - Harwinton Pegmatite, Harwinton, Connecticut. [UTM Coordinates: 659.1E / 4625.2N, Torrington quadrangle.]

Back from the road a quarry was opened in a pegmatite in order to mine for feldspar. Luckily for mineral collectors, the quarry operators selected pure specimens of feldspar and left behind minerals that would interfere with the processing of feldspar. Here, these minerals include whitish to greenish beryl forming six-sided prismatic crystals and groupings up to 20 cm long and 30 cm long black tourmaline (schorl). Permission to collect must be sought from local landowners. Happy hunting !

STOP 3 - Thomaston Dam Site, Thomaston, Connecticut. [UTM Coordinates: 660.4E / 4617.4N, Thomaston quadrangle.]

The Thomaston dam, a dry dam to hold back flood waters, was built by the U.S. Army Corps of Engineers in 1957 in the aftermath of disastrous flooding of the Naugatuck River valley in 1955. Fractured granite pegmatites and mica schist were exposed in a new railroad cut was made to relocate the rail line west of it's former location. Mineral collectors try to identify veins peripheral to the granite that cut, commonly along joints or faults, across the foliation of the Hartland. During the late stages of magmatic crystallization, large, typically incompatible elements complex with the fluoride and chloride ions and, driven by high vapor pressure, purge through the surrounding country rock leaving well-crystallized mineral samples as vug- and fracture fillings. The common minerals found at Thomaston include fluorite (in various colors), quartz, kyanite, galena, pyromorphite, wulfenite, pyrite, wurtzite (a polymorph of sphalerite), and a host of zeolite minerals including stilbite, harmotone, heulandite, and chabazite.

STOP 4 - Roxbury Iron Mine, Roxbury, Connecticut. [UTM Coordinates: 638.71E / 4601.90N, Roxbury quadrangle.]

Originally opened as a silver mine in roughly 1750, iron ore was ultimately discovered (probably much to the surprise and chagrin of investors!) and, later (by 1800), mined for iron ore. Forming an important deposit of "spathic" or "sparry" ore, to use the old vernacular, the iron ore occurs as siderite, an iron carbonate. The siderite occurs with quartz, pyrite, black sphalerite, chalcopyrite, galena, limonite, and arsenopyrite (rare). The ore formed in a 2-3 m wide subvertical vein cutting the Hartland strata at a high angle. Here, the mine occurs along a fault at the contact of the Mine Hill granite gneiss and mica quartzite, schist, and feldspathic mica quartzite and schist. Mineralization may have occurred here due to hydrothermal activity peripheral to the Mine Hill granite gneiss, a buried pluton, or be due to metamorphic melting at depth of carbonate-rich strata. Interesting reading on this mine can be found in Shepard (1837), Schairer (1931), Gates (1959), and Januzzi (1972, especially pp. 194-203).

STOP 5 - Roxbury Garnet Mine, Roxbury Falls, Connecticut. [UTM Coordinates: 641.62E / 4595.95N, Roxbury quadrangle.]

The Roxbury garnet mines were operated as small prospect pits in the 1800s(?) and were a major source of garnet abrasive material until the huge discoveries in the Adirondacks near North Creek, New York. The garnets occur as perfect 1-3 cm dodecahedral (twelve-sided) crystals embedded in a crumbly, muscovite-quartz schist and granofels of the Hartland Formation. In some rocks, 1-2 cm tabular brown staurolite crystals coexist with garnet. Mapping by Gates (1959) indicates that the mines occur along the west edge of 1.5-mile lense of similar porphyritic rocks within more typical Hartland occurring on Mine Hill (Stop 4).

STOP 6 - Tungsten Mines, Old Mine Park, Trumbull, Connecticut. [UTM Coordinates: 648.48E / 4572.08N, Long Hill quadrangle.] Note: Non-residents must obtain permission to park from the Trumbull Police Department.

Originally inhabited by Indians, the present site of Old Mine Park in Trumbull, Connecticut, is an area of historic and mineralogic interest. The Indian name Saganawamps (meaning "on the side of the hill") was derived from accounts of early English-speaking settlers in the area. Clearly, the Indian interest in the mine area was in the manufacture of arrow points from a pure quartz vein (currently fenced in). By the early 1800s, Ephraim Lane was selling mineral specimens of tungsten, tellurium, topaz, and fluorite from Saganawamps.

Up to the mid 1800s, tungsten ores and minerals were of interest to mineral collectors only as no commercial uses for these minerals were known. By 1855, however, the strength of tungsten-steel had been discovered and the search for tungsten ores became a priority. Mining rights were purchased by the American Tungsten Mining and Milling Company of of West Virginia by 1899 and construction of mine buildings began with the issue of $100,000 in bonds. The plant was shut down due to separation problems between pyrite and tungsten ore (wolframite) and by 1906, the American Tungsten Mining and Milling Company was declared bankrupt!

Crowley (1968) mapped the Long Hill quadrangle and shows the Trumbull Tungsten mine located in the Hartland Formation in a thin marble layer sandwiched between two layers of amphibolite. The presence of marble to the east of Cameron's Line is rare but according to CM, can easily be explained as a slide block (olistolith) formed within the trench sequence. Mineralization occurs at the contact between the amphibolite and marble in a typical contact-metamorphic environment with epidote, scheelite, and pyrite occurring as replacement minerals. Locally, the scheelite has been replaced by wolframite (pseudomorph) which retains the crystal shape of scheelite.

Of particular interest here is the mineral fluorite which occurs in its reddish-brown variety exhibiting fluorescence, phosphorescence, and thermoluminescence. Try this experiment at home. Boil some water on the stove then turn out the flame, turn out the lights, and drop the reddish-brown fluorite into the hot water. Voila -- thermoluminescence! Have fun collecting here and plan to return someday on your own. Remember to register your car with the Trumbull Police as Old Mine Park is intended for residents only.

1) Examine the stratigraphy of southeastern New York.

2) Understand the complex structure and history of faulting in southeastern New York.

3) Discuss the "Taconic controversy".

4) Examine and compare correlative bedrock units northward from New York City.

5) Discuss olistostromes, mélanges, and turbidites with particular reference to the Poughkeepsie mélange.

6) Identify and examine the Taconic unconformity.

7. To appreciate the change in metamorphic grade across the Taconide zone

8) To discuss plate models for the development of the Taconic range, and identify the probable source area of the Taconic strata.

STOP 1a - Proterozoic metasedimentary, granitic-, and dioritic gneiss of the Hudson Highlands, Sloatsburg Service area, I-87N. [UTM Coordinates: 568.1E / 4556.05N, Sloatsburg quadrangle.]

Behind the Thruway rest facilities and OTR pit stop, Grenville-aged (1.1 billion year old) granitic gneisses of the Hudson Highlands complex crop out. Here, the Grenville basement is well-exposed along the east wall of the Sloatsburg Service area of I-87N as hornblende-bearing granitic gneisses that are locally migmatitic (show evidence of partial melting) and cut by numerous faults (with at least three different orientations), as well as a series of joints. The intersection of joints and faults create blocs that are generally rust colored because of the weathering of iron-bearing sulphide minerals such as pyrite. The faults are distinguished from joints in that they show visible offset and often show slickensides (mineralized gouge developed along the bounding rock surfaces). The joints are often tight (and, by definition, show little or no displacement) but are commonly mineralized by fine intergrowths of mica, zeolite minerals, epidote, calcite, quartz, and pyrite, or mixtures of the above.

Interlayered within the main mass of the granitic gneiss are layers and lenses of dark-colored amphibolite and light green diopsidic calc-silicate rock. The probable parent rock (protolith) of the granitic gneisses are granite plutons, and/or quite possibly volcanic ash deposits and/or feldspar-rich greywackes. The calc-silicate rocks began life as carbonate-rich sediments and amphibolites are probably metamorphosed basaltic extrusives or calcareous, iron-rich (ferruginous) shales. As such, the overall stratigraphic sequence idealizes our concept of pre-metamorphic continental crustal rock and overlying shallow- water sediment of the cratonic realm.

In the center of the exposure note the steep post-Grenville mafic dike that contains no vestige of metamorphic fabric but is cut by the same brittle features found throughout. Based on regional mapping, these mafic dikes are either lamprophyres of Ordovician age (related to the Taconic Orogeny) or basaltic dikes of Mesozoic age (related to rifting and development of the Newark Basin).

Pull-Over STOP 1b - Carbonate rocks of the Sauk Sequence cut by mafic dikes on Route I-87N (10.2 miles north of STOP 1). [UTM Coordinates: 571.8E / 4570.3N, Monroe quadrangle.]

State law precludes stopping to look at rocks on I-87 so this pull-over stop will be discussed in the van - eyes right! After numerous miles of Proterozoic gneiss exposure on I-87N we have now passed into a major graben that exposes Cambrian to Ordovician limestone and dolostone. Here the well-layered, whitish to tan-weathering dolostone dips to the east with a strike parallel to the highway. Of additional interest here is the tan-weathering ferroan dolomite, algal laminae, and a mafic dikes that cut angularly across the bedding of the carbonate rock and in places include angular xenoliths of the carbonate host rock.

Pull-Over STOP 1c - Route I-84E, just off exit ramp from I-87N. Nonconformable contact between Proterozoic gneiss and overlying Cambrian Lowerre quartzite. [UTM Coordinates: N/A, Newburgh quadrangle.]

The geology of this area was mapped by Holzwasser in 1926. This site is famous for its rare glimpse at the basal contact of the Paleozoic shelf sequence where it rests depositionally upon the eroded Proterozoic in spectacular angular unconformity. Note how the layering in the Grenville gneiss is truncated at an acute angle against the surface of nonconformity (conveniently marked by the east-dipping poplar tree root), whereas the layering (bedding) in the massive quartzite is parallel to the surface of nonconformity. Across I-84 (eyes left!) the outcrop is also composed of graphite-bearing Proterozoic gneiss which dips gently toward and beneath us. Here, the Proterozoic is faulted against the Middle Ordovician Martinsburg Formation. Up the hill and to the east, are Sauk Sequence (Cambrian to Ordovician) carbonates.

STOP 2 - Sauk Sequence of central shelf: Wappinger Group (Cambrian - Ordovician) carbonates. [UTM Coordinates: N/A, Newburgh quadrangle.]

Across from the parking areas of Perkins and Burger King occur large cuts of Wappinger carbonates of Cambrian to Ordovician age. These essentially non-metamorphosed rocks are similar to age equivalent rocks of the Inwood Marble of New York City, the Woodville Marble belt of western Connecticut, and the Stockbridge Marble of western Massachusetts. Taken together, these carbonate units constitute the shallow-water Cambrian to Ordovician North American passive-margin carbonate-shelf strata that overlie the Lower Cambrian clastics. Here, the Wappinger carbonates form a well-layered, east-dipping sequence with meter-scale interbedding of dolostone, oolite, and chert with dark-colored ribbony solution residue (stylolites) generally parallel to bedding.

STOP 3 - Varigated red and green to gray Taconic slates on Route I-84E, Fishkill, New York. [UTM Coordinates: N/A, Newburgh quadrangle.]

In the only known (at least to JES and CM) occurrence of Taconic slates found to the west of the Hudson River in New York State, the outcrops exposed here show rocks typical of the Taconic allochthon. The slates at the extreme west end of the outcrop are dominantly red colored indicating a large amount of hematite (ferric iron, Fe+++). The interlayered greenish slate contains ferrous iron (Fe++). The greenish slate is similar in texture and color and possibly in composition to volcaniclastic rocks mapped by many farther north as the Mettawee Slates of the central Taconic range. As such, these rocks may represent volcanic-ash deposits which were interbedded with iron-rich oceanic mudstones.

We identify and discuss structural features and walk farther east along the exposure where the color changes to dominantly grey slates and siltstones which are representative of carbonate muds, poor in iron. Close examination indicates that truncated ripples occur in the silty layers from which we can interpret stratigraphic top directions. Intercalated with the grey slate occurs cm-scale layers and lenses of hemipelagic limestone and 10 cm by 40 cm limestone blocks. Close examination indicates that the larger limestone blocks are actually fragmental and contain angular to sub-rounded clasts of limestone. That is, they are actually carbonate conglomerates.

STOP 4 - Sauk Sequence: Pine Plains Formation on Lime Kiln Road. [UTM Coordinates: 598.88E / 4500.13N, Hopewell Junction quadrangle.]

The Pine Plains Formation was named by E. B. Knopf (1946) when she subdivided the Wappinger Group. Here, the cyclicity of alternating A-B-A-B facies patterns shows up as light- and dark layers(s) which strike NE and dip NW. Similar to Stop 2 (earlier today), the light-colored layers were carbonate sand and the darker layers consisted of carbonate mud. Layers of chert (siliceous ooze), sandstone, and intraformational breccia are common along the length of the exposure. Symmetrical wave-generated ripples occur with ripple crests roughly parallel to the strike direction. Finely laminated layers are the result of carbonate deposition during the formation of algal stromatolites. In addition, evaporite nodules have dissolved to form micro-geodes now filled with calcite, silica, pyrite, and chalcopyrite (the result of burial and dissolution). Burial has also prompted the development of stylolites as branching layer-parallel dark "injections" (cross-cutting dissolution residues) at all scales.

STOP 5 - Tippecanoe Sequence: black shale and interbedded graywacke in Mesier Park, Route 9D, Wappingers Falls, New York. [UTM Coordinates: 590.17E / 4605.48N, Wappingers Falls quadrangle.]

This will be a brief stop at a convenient place for viewing the weathered massive graywacke layers in the Tippecanoe Sequence (M. Ord.). Here, the graywackes form highly jointed, massive outcrops with approximately north-south strikes and steep easterly to vertical dips. Sedimentary structures include local shaly interbeds, large-scale cross beds, rolling ripple laminae, and amalgamated ripple bedding. These rocks were deposited in the foreland basin that replaced the shallow-water carbonate shelf on which the Sauk Sequence was deposited.

STOP 6 - Tippecanoe Sequence: black shale and interbedded graywacke exposed in Wappinger Creek, beneath bridge on Route 9D, Wappingers Falls, New York. [UTM Coordinates: 589.94E / 4605.67N, Wappingers Falls quadrangle.]

A short stop (time permitting) to look over the edge of the bridge and examine graywackes differentially eroded by Wappinger Creek. Here, the creek has deeply eroded the shaly interbeds and the massive graywackes form prominent outcrops in the creek bed. Note the potholes formed by swirling waters. With a strike essentially parallel to the south-flowing creek, these beds are oriented steeply eastward to vertical in dip and control the orientation of Wappinger Creek. Also note the building stones used along the bridge. These are potassium feldspar-rich sandstones (arkose) probably from the Newark Basin.

STOP 7 - Sauk Sequence: Pine Plains Formation (Upper Cambrian), Wappinger Group, at entrance to South Hills Mall. [UTM Coordinates: 590.16E / 4607.52N, Wappingers Falls quadrangle.]

The roadcuts directly north of the parking lot opposite the entrance to the mall expose thick bedded hummocky dolostones showing alternating A-B-A-B lithologic layering. Here, as in Stops 2 and 4, the light-colored layers were originally massive, coarse-textured carbonate sands and the darker layers are finely laminated carbonate muds. Stylolites are developed in two directions, one set parallel to bedding (often with branching forms) and the other set at a high angle to bedding. The presence of the secondary high-angle set is evidence that layer-parallel shortening here was greater than in the exposures of these carbonates we have seen previously. Structurally, the rocks of this stop dip beneath the graywackes exposed at Mesier Park and Wappinger Falls thus forming the northern limb of a syncline. Of further geological interest here, note the diagenetic bedding (dark streaks), burrow mottles resulting from bioturbation of soft sediment by burrowing creatures, micro-geodes filled with carbonate, and high-angle brittle faults.

STOP 8 - Poughkeepsie Olistostrome(?) or Mélange(?) Unit, Kaal Park, under the east footing of the Mid-Hudson Bridge. [UTM Coordinates: 588.00E / 4617.15N, Poughkeepsie quadrangle.]

One of the perplexing problems facing geologists in studying rocks associated with subduction zones, forearc and backarc basins, and in this case, arc-continent collisional orogens, is the identification of pre-tectonic soft-sedimentary slump deposits (called olistostromes) from tectonically deformed packages of incipiently lithified sediment (mélange) formed penecontemporaneous with the emplacement of thrust sheets. Here, in spectacular poison-ivy-covered exposures beneath the bridge, we will attempt to make observations and discuss this problem in order to decide, in a living laboratory - "Well Mabel, is it sedimentary, tectonic, or a combination of the two?". Because of the fact that your trip leaders are in partial disagreement over this matter, with JES supporting a soft-sediment slump model (naturally) and CM (of course) supporting the tectonic model, perhaps your observations can settle this once and for all without the need for fisticuffs, late in the day, on raw rock, in the poison ivy.

Fact 1 - The rocks are indeed black argillite in which numerous blocks of quartzose arenite in variable orientation exist. The arenite blocks range from cobble- to boulder size, show internal grading (tops indicators), laminated upper portions, and glazed bottoms (a result of sedimentary loading). The blocks are surrounded by a shaly- to slaty black matrix. In addition, larger, 2-3 m thick, internally bedded masses are surrounded by shaly- to slaty sheared margins and found rotated into various attitudes. The interbeds of arenite are separated by the same black shale (slate?) found elsewhere in the exposure. Taken together, we see what most geologists would argue is a "broken formation". But a broken formation of what? Interbedded shales and arenites which could be none other than the Tippecanoe Sequence (Middle Ordovician) flysch part of the filling of the foreland basin (great exposures to be seen at Stop 9 (tomorrow morning)). By contrast, Fisher, and others, say these rocks belong in the Taconic Sequence and are related to a subduction zone.

Fact 2 - The unit is strongly deformed; the outlines of the arenite blocks are rounded to angular. Typically, arenite masses are flattened parallel to the sub-horizontal slaty cleavage which forms a crude clast shape-fabric to the outcrop.

Fact 3 - Many of the blocks are elliptical in shape showing flattening in the subhorizontal dimension and linear elongation (within the plane of flattening) toward the east.

Fact 4 - The slaty- to shaly matrix anastomoses around the blocks of arenite (not through them) and the outlines of the blocks are sharp, not wispy or gradational.

In the light of these facts, CM argues (without significant hesitation) that the unit represents a ductile tectonic mélange but leaves open the possibility that limited internal soft-sediment deformation in the autochthon preceded the effects of low-angle thrusting. CM argues that the dominantly pelitic matrix, monomict clast population, pervasive shearing of the matrix, and sharp clast outlines all argue for a ductile mélange call on this one (JES note: based on the rules outlined by CM!). CM views the overall crude shape fabric and rounding of the clasts as tectonic in nature and the strong alignment of elliptical clasts vectorally pointing toward the direction of overthrusting. In most thrust zones, strong down-dip alignment of linear elements is taken to indicate the tectonic-transport direction, an observation that would certainly "fit the model" of Taconian continentward advancement of allochthons here, or, for that matter, post-Taconic low-angle faulting. The lack of soft, wispy outlines, the lack of injection of mud into the "non-lithified" arenite blocks, and the lack of polymict clasts argue against a pure olistostrome model for the exposure in his view. CM is not opposed to the concept of early, limited soft-sediment deformation but would tend to interpret this exposure the result of incipient subduction of the medial Ordovician foreland basin beneath the advancing active overthrust toe of the Taconic subduction complex. Implicit in this idea is that the foreland basin fill (the Tippecanoe Sequence, here) was dragged down into the trench for hundreds of meters or more, with mélange formation and subsequent shearing related to subduction. As these rocks are considered part of the autochthon, they may have been involved in incipient subduction during the final stages of Taconian arc-continental margin convergence! Deformation of the Poughkeepsie Mélange may also be the result of post-Taconic (post Medial Ordovician = Acadian or Appalachian) low-angle faulting or shearing.

JES points out that the terms used by Fisher and Warthin are not synonymous, and that clarity will be improved by using them as originally defined. Fisher has expressed his interpretation by applying "mélange" as a formational designation. But a mélange is not the same thing as an olistostrome, a wildflysch, or a chaos, which are clearly products of subaqueous, gravity-driven "mass-wasting" activities. JES argues that exposed here is an olistostrome because "blocks" are the shallow-water type and argues that the arenites (now quartzites) are possibly topset beds of a delta. He views the imbrication of the blocks as being a result of gravity slippage which caused them to become bent before cementation. According to JES, the pieces of the arenites moved downslope to deeper water where pelites were being deposited as the large slabs are parallel to the depositional surface (i.e. - bedding). JES suggests that the pieces are too small to have been pried loose by an overriding overthrust sheet and that deep burial and deformation occurred later, resulting in the cleavage. CM asserts that JES may have slumped on this interpretation! What do you think? Can they both be right? Of course! -- This is the appeal of academia.

1. The only kind of material forming the blocks is coarse quartzose arenite (quartzite? as contrasted with Austin Glen graywacke). Discrete bits and pieces of arenite are scattered at random everywhere within the cleaved black-shale matrix, in all possible orientations. Some clearly show sole marks that indicate original bottoms. Some that have been folded are completely upside down. At N end, the large continuous layers may be part of an isoclinal anticline, with tops both directions away from the shale in the middle.

2. What age are the disrupted arenites? To JES they look most like the so-called Quissaic Quartzite, DWF's Upper Ordovician molasse present on W side of Hudson River. An age as late as Late Ordovician for the disrupted arenite would scuttle the DWF idea of a Taconic mélange here. Is Quissaic the top of the Austin Glen (poss. Ramseyburg member of Martinsburg) or even younger than the upper shale member (=Penn Argyl member)? If so, then syndepositional faulting in the foreland basin during deposition of the Penn Argyl member could be an explanation for simultaneous deposition of the matrix here and the disruption of the arenite. This assignment eliminates any "Normanskill" age even if one accepts the Late Trentonian assignment of Ruedemann and WNB Berry).

If the breaking of the arenites is not syndepositional but is tectonic, then when was the deformation and tectonic mixing? Acadian? CM suggests that is possible. Or even Appalachian? Both would be in a backarc setting, not within the main subduction zone. Similar relationships are described by Vollmer and Bosworth (1984) for other localities west of the Taconic range.

JES afterthought: what about this as one of the Queenston deltas? The big news on "deep-water" (> 20 m) modern deltas from the NW Gulf of Mexico is that the sand brought to the ends of the distributary channels during floods founders into the thick hydroplastic muds (the H. N. Fisk "bar-finger sands") and all manner of slumping takes place even on very low slopes. The fact that no other kinds of coarse arenites are present or other kinds of rocks (carbonates, granites, etc. - despite Fisher's pronouncement on a variety of blocks) is consistent with a deltaic interpretation. Also, the matrix interbedded with arenites in large, multi-bed masses is the same as the general matrix (the suspended load of the river?). This delta idea needs checking. If correct, it completely revises the interpretation here and the tectonic significance of the old Poughkeepsie Mélange goes slumping into the scrap heap.

STOP 9 - Tippecanoe Sequence: flysch of foreland-basin filling, west footing of Mid-Hudson Bridge, NY Route 44 (old and new) and Johnson Iorio Town Park, Highland, New York. [UTM Coordinates: 587.11E / 4617.22N, Poughkeepsie quadrangle.]

The rocks magnificently exposed on the west end of the Mid-Hudson Bridge are part of the Tippecanoe Sequence (Middle Ordovician) flysch deposits, the bulk of the filling of the foreland basin that supplanted the carbonate shelf when the passive-margin plate setting became convergent. The new location of US Route 44 going west from the Mid-Hudson bridge has involved making splendid deep cuts through the coarser member of the Middle Ordovician flysch (possibly the Ramseyburg Member of the Martinsburg Formation, but use of that name here is not a matter of general agreement; others would opt for Austin Glen). We plan to spend much of our time in the cuts along the former location of Route 44, now a town park and thus not subject to the problems of fast-moving vehicles and anxious Bridge Authority patrols, who seem determined to keep geologists from looking at these splendid strata. We may try to look at the new cuts on the N side of the new location of US Route 44; to do so we shall park along the old Route 44 and climb up a hill to the new cuts.

The fine-grained, brown-weathering sandstones display a complete set of primary structures formed by deposition of fine sand from currents moving fast enough to create "normal" ripples, to cause these ripples to migrate downcurrent, and in some instances, to cause the ripple laminae to be oversteepened, even overturned, and convoluted. Examples can be found of climbing ripple-drift ripples, of climbing partial-drift ripples, of climbing oversteepened ripples, and of climbing sets of convoluted laminae.

In general, the coarse graywacke beds display few internal sedimentary structures. Along the basis of many, one can see evidence that the newly deposited coarse sediment foundered into what must have been a hydroplastic (Shrock, 1948) substratum.

STOP 10a - Taconic Sequence/Tippecanoe Sequence contact: The Taconic thrust (?) or post-thrust normal fault (?), Duchess County Road 21, Noxon, New York. [UTM Coordinates: 599.41E / 4610.87N, Pleasant Valley quadrangle.]

This exposure was described by Fisher and Warthin (1976; Stop 3 NYSGA Trip) and Bence and McLelland (1976; Stop 1 NYSGA Trip) and we borrow from their discussion but differ from their interpretation. Firstly, the rocks exposed in the large roadcuts are slates (metamorphic rocks) not shales as reported by Fisher and Warthin. We here argue that the eastern end of the exposure consists of variegated slates of the Taconic Sequence (thus, part of the Taconic allochthon) but that based largely on physical stratigraphic grounds, the western part, indeed, consists of black slates of the Tippecanoe Sequence (which also includes such formations as the Martinsburg, Normanskill, and Walloomsac). If we are correct, then within these roadcuts is a major tectonic boundary between the two so-called "pelitic" sequences! One possibility is that the tectonic boundary is none other than the Taconic overthrust itself.

Starting at the east end of the exposure (north side of Route 21) one finds pale green to red to maroon slate with cm-scale interlayers of nonfossiliferous, gray hemipelagic limestone. These strata are similar to the Taconic slates of Stop 3 (yesterday); we would correlate these units directly and argue that the depositional environment is that of the outermost continental rise or deep ocean. The west end of the exposure consists of tan-weathering black slates that are typical of the Tippecanoe Sequence (Middle Ordovician) foreland-basin flysch deposits witnessed yesterday (Stop 8) and earlier today at Stop 9.

Structurally, the rocks have experienced a number of folding events, the oldest of which resulted in long-limbed recumbent isoclinal folds with subhorizontal axial surfaces. The penetrative slaty cleavage in the slates is parallel to, and believed to be contemporaneous with, the sub-horizontal fabric. Throughout most of its extent, the map pattern indicates that the Taconic thrust dips at a low angle. These shallow-dipping recumbent structures, which are typical of the sole thrust areas of the Taconic allochthon, have been refolded by north-plunging folds with westward-dipping axial surfaces as well as by refolded drag folds. The multitude of refolded drag folds may have formed during an episode of steep faulting as argued above.

Pull-over STOP 10b - Spectacular westward view of Catskill Mountains and Hudson Valley. [UTM Coordinates: 605.40E / 4657.90N, Ancram quadrangle.]

Title says it all!

Pull-over STOP 10c - Thinly layered Taconian grayish green slate and hemipelagic limestone. [UTM Coordinates: 600.71E / 4672.72N, Hudson South quadrangle.]

The road cut exposes Taconic slate and interbedded light-gray-weathering hemipelagic limestone similar to Stops 3 and 10 seen earlier. Here, the limestone is very well layered, not metamorphosed, and forms a distinctive Taconic lithology.

STOP 11 - Taconic unconformity, bedding thrusts, and late faults, south end of Becraft Mountain. [UTM Coordinates: 599.75E / 4673.42N, Hudson South quadrangle.]

Only a few places exist where budding geologists can place their fingers on the pulse of a former orogeny. In this exposure, the Silurian Rondout Formation rests with angular unconformity on cherts of the Mount Merino Formation (Middle Ordovician Tippecanoe Sequence). The surface of unconformity is quite irregular and the angular discordance between beds above and below is small, perhaps as a result of minor thrust faulting at the Rondout-Mount Merino contact. Within the base of the brown-weathering Roundout (a silty dolostone), however, clasts of black Mount Merino chert and quartz occur. This would be expected if the contact is indeed one of unconformity!

The Rondout is overlain by highly laminated, whitish rocks of the Manlius Formation, but the Rondout appears again above the Manlius. What gives? Bedding thrusts occur within the Rondout and overlying Manlius. The field exposure shows the bedding thrusts (the lower one outlined by a calcite vein) which imbricate the Siluro-Devonian carbonates above the surface of unconformity with local folding ("rolling") of the Rondout. Again, clear evidence for significant post-Taconic, low-angle thrusting! Toward the south, the Manlius dips below the calc-arenites of the overlying Coeymans Formation and possibly massive limestones of the Kalkberg and New Scotland formations but significant complications are present.

STOP 12 - Taconic unconformity and other goodies, east side of Becraft Mountain. [UTM Coordinates: 602.53E / 4674.95N, Hudson South quadrangle.]

At the south end of this exposure on the east side of Becraft Mountain, we find support for our previous interpretations at Stop 11 and find the Rondout in profound angular unconformity with older strata below. But here, the older strata do not belong to the Tippecanoe Sequence, as at Stop 11, but consist of typical variegated red- and green allochthonous Taconic slates. Here, we are on the eastern limb of a syncline (which underlies Becraft Mountain) with the Rondout bedding parallel to the surface of unconformity.

Northward along the road note the change in orientation of the Taconic slaty cleavage beneath the surface of unconformity and the fact that the Manlius begins to crop out in the hillside above the Rondout. Farther north the dip of the bedding steepens and the stratigraphic relationships have been complicated by low-angle bedding-plane thrusts and high-angle solution cleavage. These exposures support our contention that two significant episodes of low-angle thrusting occurred before high-angle faulting and gentle folding of the Helderbergian strata. The relative ages of these events are known (post-Middle Ordovician low-angle Taconic thrusts, followed by post-Taconic low-angle thrusts, followed by high-angle faulting) but the absolute ages await further investigation.

STOP 13 - Evidence of progressive metamorphism in the Paleozoic Everett Phyllite, Bashbish Falls, Copake, New York and Massachusetts. [UTM Coordinates: N/A, Bashbish Falls quadrangle.]

Be prepared for a half-hour eastward stroll along the north side of Bashbish Creek. Note the nature of the rocks on the trail. These are Taconic slates and phyllites described by Zen and Hartshorn (1966). Near the trailhead the rocks are greenish slates and phyllites rich in chlorite mica. Near Bashbish Falls, the rocks are decidedly of higher metamorphic grade with porphyroblasts of garnet and staurolite sticking up out of the foliation surface and forming a spotted schist. Thus the complete metamorphic lithologic transition from slate to phyllite to schist can be observed along our walk.

By the time you reach Bashbish Falls, you have crossed the New York-Massachusetts state line. At the falls, note the foliation on the steeply dipping Everett Schist. The Everett is considered to be of Cambrian to Ordovician age and part of the Taconic allochthon. It rests structurally upon the bedrock of the autochthon consisting of the Walloomsac (=Egremont Phyllite), and underlying Stockbridge Marble.

STOP 14 - The Walloomsac Formation (Tippecanoe Sequence, mid Ordovician), NY Route 55. [UTM Coordinates: 613.40E / 4602.51N, Poughquag quadrangle.]

The rocks in these long roadcuts have been mapped as Walloomsac Schist by Bence and McLelland (1976; Stop 6 NYSGA) but in their own words, "whether they are, or not, is open to question." The rocks include quartzite, quartz-feldspar gneiss, and biotite-rich schist which contain garnet and kyanite, indicators of amphibolite-facies metamorphism. The kyanite occurs as bluish blades, 3 mm to 2 cm long, particularly concentrated within more-micaceous layers.

STOP 15 - Metamorphosed Briarcliff Dolostone (Sauk Sequence, Cambrian to Ordovician), NY Route 55. [UTM Coordinates: 616.07E / 4600.79N, Pawling quadrangle.]

This stop focuses on how the effects of metamorphism increase rapidly from northwest to southeast across the Taconide zone. Note that we are less than 15 miles (9 km) from our easternmost stop (Stop 4) in the Wappinger Group. Here, in an outcrop described by Bence and McLelland (1976; Stop 7 NYSGA) and McLelland and Fisher (1976; Stop 7 NYSGA) metamorphosed equivalents of the Sauk Sequence (Layer IIA(W) are exposed in cuts on either side of the road.

Along either side of Route 55, large cuts show gray-weathering, light-colored Briarcliff Dolostone with yellow, white, and black chert layers up to 5 cm thick. Accessory minerals include quartz, phlogopite, tremolite, diopside, and local serpentine. Structurally, tight to isoclinal folds, which occur in the dolostone with generally shallow axial surfaces, refold an earlier phlogopite foliation. These early fabrics are refolded by NNE-trending folds with steep plunges and a younger set of N-S-trending upright, dominantly open folds. Note disharmonic folds develped because of the profound differences in mechanical behavior between the ductile marble and brittle siliceous layers.

Petrologically, this stop is of interest because it affords the opportunity to examine the development of calc-silicates at grades approaching the first sillimanite isograd. Throughout the roadcut diopside, tremolite, and phlogopite are abundantly developed in the appropriate lithologies and are best seen on the weathered surface at the top of the roadcut. Recrystallization from progressive metamorphism, of original carbonate-rich sediments has resulted in a major change in the minerals.

Regionally, these relationships indicate that in a very short distance metamorphic grade increases rapidly from west to east. Ratcliffe (1984) argues that steepened metamorphic isograds in this region are the result of tight, asymmetric folding of the isograds along steeply dipping limbs. In concert, or perhaps alternatively, the data could be interpreted to indicate more uplift to the east, with originally deeper rocks now exposed at the surface, perhaps in response to high-angle brittle faulting.

1) To study the four major bedrock units exposed in the trip area. From top downward, these are: Layer V, Newark strata; Layer III, Silurian and Devonian; Layer II, where not metamorphosed; and Layer I, Proterozoic of the Ramapo block-Reading Prong. We will start with the oldest unit and study progressively younger units, but see Layer V only in passing.

2) To study the geologic structure, on scales both large and small, with particular emphasis on features found in the post-Taconian strata.

3) To examine the geologic relationships of the local valley-and-ridge type morphology associated with the downdropped Silurian and Devonian strata of the Green Pond-Bellvale-Schunnemunk belt.

4) To understand the relationship between slaty cleavage and bedding in folds.

5) To learn how to use slickensides to infer direction of relative movement on faults.

6) To note any flow-direction features made by glaciers or left in the glacial sediments.

STOP 1- Proterozoic Gneiss Exposures on NY Route 17A, Tuxedo, New York. [UTM Coordinates: 567.8E / 4564.6N, Sloatsburg quadrangle.]

Our first stop today is just a quick stop to examine Proterozoic gneiss of the Hudson Highlands. These gneisses are predominantly felsic; their layering and foliation are distinct and they contain variable percentages of the mafic minerals pyroxene, amphibole, and biotite. Other rock types include thin, dark layers of amphibolite gneiss and discordant bodies of granitic pegmatite. Locally, the pegmatite is internally foliated as well. This indicates that the granitic magma was emplaced before a phase of penetrative deformation had been completed. Ample evidence for granitization comes in the form of wispy pegmatite-felsic gneiss contacts, and partly digested gneissic xenoliths.

Here, the gneissic layers are subvertical and they have been cut by numerous brittle faults. Although CM and JES were not able to determine the relative ages of the faults (at 40 mph), we are convinced that both high-angle- and low-angle faults exist in this exposure. Both of these sets of structures dip eastward. As argued later, and on other On-The-Rocks field trips, the significance of low-angle faults within the Proterozoic rock is that they may be related to major dislocations within the basement. The absolute age(s) of such displacement(s) is (are) unknown.

Alternatively, according to JES, these northwest-trending cross structures might possibly be mid-Jurassic strike-slip faults. In the vicinity of New York City, CM has found ample evidence for northwest-trending faults. The movement histories of these faults are complex and include an early component of strike-slip movement. CM suggests that these faults, which are on line with transcurrent faults of the Atlantic Ocean basin, are active today because of readjustments of the oceanic lithosphere during contemporary sea-floor spreading and, therefore, are potential seismically active faults.

STOP 2 - Middle Devonian Strata, eastern crest of Bellvale Mountain. [UTM Coordinates: 560.2E / 4566.3N, Greenwood Lake quadrangle].

Our interpretation of the relationships at STOP 2 are based on the results of the 1981 "ad-hoc" Barnard summer geologic "field camp," during which JES instructed a hardy band of 6 (including 3 Barnard junior geology majors) in the fundamentals of field observations and geologic mapping and an advanced undergraduate mapping course in 1997 at Hofstra University conducted by JES and CM. The mapping projects started at STOP 2 and progressed northeastward along the crest of Bellvale Mountain, with emphasis on three units: the graded graywackes of the lower Bellvale, the coarsely cross-bedded graywackes of the Upper Bellvale, and the quartzose, pebbly Schunnemunk Conglomerate.

Topics discussed in the guidebook include characteristics of steeply dipping graywackes of the lower Bellvale and coarse, quartzose Schunnemunk Conglomerate; plant debris in the graywackes; upward-fining cycles in the Schunnemunk; evidence for original top direction of steeply dipping strata; "technicolor" slickensides; and inferred direction of fault movement.

STOP 3 - Schunnemunk Conglomertae and Upper Bellvale Formation, NY 17A, western crest of Bellvale Mountain. [UTM Coordinates: 559.6E / 4565.9N, Greenwood Lake quadrangle.]

In view of the scenic panorama to the NW are isolated knobs composed of Proterozoic rocks (klippen), the Appalachian Great Valley, Schunnemunk Mountain (to the NE), and the Shawangunk-Kittatinny ridge in the far distance. In exposures behind us the rocks here are typical Schunnemunk, with upward-fining cycles starting with pebbles at the base and grading up into shale. Notice the irregular bases of the pebbly layers, the clasts of red slate (as well as of white quartz), and the cross strata. Two cleavages are present here. As usual, the slaty cleavage is best developed in the fine-textured strata. Notice what becomes of the cleavage in the coarser layers.

STOP 4 - Tippecanoe Sequence (Martinsburg Slate), County Route 1, west of Warwick, New York. [UTM Coordinates: 592.8E / 4568.3N, Warwick quadrangle.]

The purpose of this stop is to demonstrate the relationship between slaty cleavage that is parallel to the axial plane of a fold and the bedding, and also to examine the Bushkill Member of the Martinsburg Formation. Notice that in the axial part of the fold (crest of an anticline or trough of a syncline), the slaty cleavage cuts the bedding at a high angle.

STOP 5 - Franklin Marble (Grenville Proterozoic), Orange County Route 1A, between Warwick and Pine Island, New York. [UTM Coordinates: 551.2E / 4569.1N, Pine Island quadrangle.]

In sharp contrast to the felsic Proterozoic gneisses exposed at Stop 1, the Grenville here consists of massive graphite-bearing carbonate rocks. In fact, this entire exposure might be considered a single crystal of calcite but we suspect that significant heating and recrystallization have taken place. In fact, CM and JES are of the opinion that we are looking at "igneous" carbonate here that was thoroughly molten and then crystallized at depth to form such large crystals (more than 5- to 10 cm in size). At this stop, mineral enthusiasts will be happy to collect beautifully twinned calcite, graphite, quartz, calcic plagioclase, amphibole, diopsidic pyroxene, phlogopite, muscovite, idocrase(?), and a few specimens of red-colored idontknowite and leverite. These minerals are typical of skarn deposits (contact-metamorphic rocks). If the skarn interpretation is correct, then a buried intrusive lurks in the vicinity.

These massive carbonate rocks lie along strike with and thus are considered to be correlative with the massive Franklin Marble and identical marbles exposed at Sparta, New Jersey. Likewise, their mineralogic composition is identical with Grenville-aged Proterozoic marbles mapped throughout the Adirondack massif of northern New York State. Many of you apply lime to your lawns from the Limecrest Quarry which is located in this marble belt (look for the Limecrest trademark next time you shop!).

STOP 6 - Coarse-textured Tippecanoe Sequence - either the Ramseyburg (M. Ord.) or the High Point (U. Ord.) Members of the Martinsburg Formation. Cuts in Ramps at I-84 interchange at Mountain Road and Smith Corners. [UTM Coordinates: 532.3E / 4579.1N, Unionville quadrangle.]

Here we approach the NW side of the Appalachian Great Valley and its bounding strike ridge underlain by NW-dipping Lower Silurian conglomerate/sandstone. Along this side of the Great Valley, the dips of Ordovician and Silurian strata typically are the same; we are outside the belt of Taconian folds. The coarse Martinsburg strata here display the features of what geologists refer to as a "flysch." The coarse layers commonly show grading; their bases are sharp and may display indications that the current which deposited the coarse sediment interacted with the muddy bottom over which it flowed. See how many features you can find that were made by currents, either now preserved as counterparts on the bases of the sandstone beds or within them, and what conclusions you can draw about the direction of flow of the currents on the Ordovician sea floor.

STOP 7 - Shawangunk Formation, High Point State Park, New Jersey. [UTM Coordinates: 528.35E / 4574.25N, Port Jervis quadrangle.]

STOP 7 is another rocks-plus-scenic-vista locality. The Shawangunk and underlying Martinsburg here have been closely folded together, an arrangement that is not typical of the monoclinal strike ridge to the NE and SW. Our purpose is to examine the massive sandstone/conglomerate, look for sedimentary structures to indicate tops, and to relate this resistant formation to its topographic expression.

STOP 8 - Upper Cambrian part of the Sauk Sequence (Cambro-Ordovician carbonates). Roadcut along NJ Route 94, Hamburg, New Jersey. [UTM Coordinates: 534.30E / 4455.45N, Hamburg quadrangle.]

The features to see here include the alternating coarse-fine layers and the characteristics of each, plus their mutual interpenetration along stylolite seams and the chert. Layers that consist of original sand-size sediment contain quartz, intraclasts of the former lime mud, and ooids. Cross laminae are common. The finer-textured layers are well laminated. Algal stromatolites characterize certain layers. The repeated pattern of couplets of coarse- and fine layers has been interpreted as being the result of upward shoaling from a subtidal environment to an intertidal/supratidal environment.

STOP 9 - SE-vergent anticline in the Green Pond Formation, SE of Newfoundland, NJ. Roadcut in the median of NJ Route 23. [UTM Coordinates: 547.4E / 4542.7N, Newfoundland quadrangle.]

This splendid exposure enables one to examine the crest of an anticline that is totally accessible. Trace the layers carefully and see if they are as continuous as they might seem to be. Notice the direction of asymmetry of the folds; the steep limbs are on the SE and the gentler limbs on the NW, just the opposite of most Appalachian folds. This area is part of the Green Pond outlier where the width of the outcrop of the Green Pond belt increases so that all the strata from the Green Pond to the Schunnemunk are present. The wider outcrop belt also coincides with the localities in which the basal Silurian cuts across the older Paleozoic strata to rest on the basement.

1) To examine the depositional features in the deltaic sediments at Croton Point Park.

2) To compare and contrast the red-brown tills with those having colors other than red-brown.

3) To study the gray varved clays that were deposited in the same lake into which the delta grew, but that were protected by higher-standing parts of the former lake bottom (underlain by till) from the influx of sand from the east.

4) To relate the modern depositional setting (intertidal marsh, beach, and boulder-strewn flats) to the Pleistocene sediments.

5) To infer a chronology of events that took place during the Pleistocene glacial age(s) and the Holocene.

6) To study the boulders washed out of the till(s) as indicators of provenance. In this respect, we will concentrate on the kinds of mafic rocks derived from the Cortlandt Complex, a pluton near Peekskill, and the surrounding country rocks, and,

7) To examine the bedrock geology in the vicinity of Peekskill Hollow, a source for many of the boulders in the NNE-derived tills exposed to the south.

STOP 1 - Pleistocene deltaic sediments along cliff face and SST (Sanders Scientific Trench) in beach sands. [UTM Coordinates: 592.8E / 4560.0N, Haverstraw quadrangle.]

Walk northward beyond the Park Office then turn right along the beach at opening in fence. A couple of hundred yards along the shore look up (to right) to find the preliminary dig site. We have four stops at Croton Point Park as shown on the location map in our guide. Note the view to the north of the Hudson Highlands and electric power-generating plants (including Indian Point nuclear reactors). To the west note the north end of the Palisades at High Tor where this sheet of igneous rock swings inland away from the Hudson River. The undulating lowlands to the east and northeast are underlain by metamorphic rocks of the Manhattan Prong that project upward from beneath the water of the Hudson River.

The dig site will expose the lower part of the deltaic sands of the Croton River delta. The delta was built into Lake Albany that formed when the Woodfordian glacier retreated northward past Croton Point Park. This lake persisted until roughly 12,000 years ago (based on radiocarbon date published by Newman and others, 1969). Glacial Lake Albany drained abruptly when a glacial moraine dam at the Narrows broke and water surged out across the shelf, eroding the Hudson Shelf Valley. Then a very rapid submergence took place, and the Hudson estuary formed and has stayed that way ever since.

STOP 2 - Cliffs at Teller's Point to examine oyster middens, red-brown till overlying gray till containing decayed granite boulders and erratics from Cortlandt Complex and boulder-residue "beach". [UTM Coordinates: 592.38E / 4557.81N, Haverstraw quadrangle.]

The cliffs at Teller's Point are immediately across (about 2 km or 1.2 miles) the Hudson River from the Palisades intrusive just south of Haverstraw, New York. At the left of the path just before the steep descent to the river are some oyster shells from an Indian midden. Walk down the path to the water's edge and begin by scraping off loose sediment from the cliff face. Note that two tills are present here. A red-brown till caps the cliff; at a level of about 3 m above the water can be seen the top of a gray-brown till that persists down to water level. We know that the red-brown till is associated with a glacial advance from New Jersey (from NW to SE): it contains boulders and pebbles of various facies of the Palisades trap rock, red-colored sedimentary rocks from the Newark Supergroup, the Green Pond Conglomerate, and chips of anthracitic coal.

The lower gray-tan till contains rocks not found west of the Hudson River. Rather, the distinctive rocks eroding out of the lower till consist of igneous- and metamorphic lithologies which crop out to the east of the Hudson, mostly from regions due north of us. The feldspars in the dark, smaller stones in the lower part of the cliff face have totally decayed.

A list of boulders averaging from 2 m to pebbles in size observed at our pre-trip investigation follows. See if you can find these distinctive rock types and perhaps identify some odd lithogies that we've missed. Boulder bashing is an acceptable method of investigation here.

Boulders, boulders everywhere------

Diabase showing fine, medium, and coarse textures

Hornblende diorite

Poikilitic pyroxenite

Pyroxenite

Gabbro, norite, and poikilitic norite

Granite and granite pegmatite

Red-orange granite

Granite gneiss +/- garnet, epidote

Hornblende gneiss

Mica schist

Phyllite

Amphibolite

Foliated granite

Hematitic quartzite

Clean quartzite

Greenstone

Folded, foliated rocks

Red jasper

Limestone

Dolostone

Arkose

Siltstone

Graywacke

STOP 3 - Squaw Cove beach: Gray varved clay overlying red-brown till overlain by fluffy brownish sand and boulder-residue "beach." [UTM Coordinates: 592.27E / 4558.37N, Haverstraw quadrangle.]

Walk through wooded area to the beach for Stop 3. At the beach, gray varved clay is exposed at the top of a low bluff. A dig a few meters to the N from where the pat ends shows that this same gray clay overlies the red-brown till. We note many more reddish Newark sandstone boulders here plus mafic rocks of the Palisades intrusive sheet (in comparison to Stop 2) and lesser mafic- and ultramafic rocks of the Cortlandt intrusive suite.

On our pre-trip investigation on 21 October 1992, we found a large dropstone in the clay. (A dropstone is a stone that started its career by being incorporated into a glacier. At the terminus, the glacier calved into the water of a lake, and the ice+stone became an iceberg. The iceberg drifted out into the middle of the lake. When the iceberg melted, the stone to the bottom, coming to rest in a quiet environment where otherwise only clay was being deposited.) On trip day, we plan to clean up a face to show the relationship between this dropstone and the laminae in the clay.

STOP 4 - Enoch's Nose: Drumlin, red-brown till, red-brown outwash, upper yellow-brown till, oyster middens, and boulder-residue "beach". [UTM Coordinates: 592.1E / 4559.9N, Haverstraw quadrangle.]

Walk along the trail to the large erratic boulder marked by two smaller rocks. The elongate shape of the promontory suggests that it is a drumlin, shaped by the advance of glacial ice. The bluffs here consist of two red-brown tills with local reddish outwash between two units of till. Note that no gray-tan till as observed at Stop 2 is exposed here. However, boulders of the Cortlandt Complex suggest that some gray till or other must have been eroded. Possibly the older such till is present exposed at or below river level. Possibly these boulders came from the upper yellow-brown till that caps the hill.

Walk along the boulder beach. Notice the large erratics from the Cortlandt Complex and a few Newark sandstone boulders. Dig at the NW end of the promontory and, depending on time, we'll look at the large cliff at the north end of the drumlin. Note the oyster middens on the terrace level at the boundary between the youngest yellow-brown till (capping the drumlin) and the older red-brown till(s) exposed in the eroding bluffs.

STOP 5 - Igneous flow layering in norite, Pluton V of Cortlandt Complex. [UTM Coordinates: 588.94E / 4568.78N, Peekskill quadrangle.]

The purpose of this stop is to examine flow layering in igneous rocks of Pluton V (norite) of the Cortlandt Complex. We are situated at the western edge of the Central Basin of Balk (1927). Here notice the well-developed, northeast-dipping coarse- to medium-textured norite with an igneous flow layering. The layers consist of plagioclase laths (reddish tint) and hypersthene (an orthopyroxene). Note the northeast-dipping lithologic contact between texturally and mineralogically different phases within the igneous rock, the presence of schlieren (mafic clots), and the compact, dense mafic rock here. Are you convinced that bedrock such as some of the coarse layers exposed here could have supplied some of boulders we have just examined at Croton Point?

STOP 6 - Glaciated Inwood Marble and Manhattan Schist? [UTM Coordinates: 587.29E / 4567.44N, Peekskill quadrangle.]

Low outcrop on the north side of 11th Street of dolomitic- and calcitic Cambro-Ordovician marble exhibiting glacial grooves and scratches. On the south side of the street occurs marble plus phyllite also showing glacial striae and grooves. We think it's the Annsville Phyllite.

STOP 7 - Poikilitic flow-layered norite (Pluton V) with xenolith of isoclinally folded, contact-metamorphosed Inwood marble. [UTM Coordinates: 589.65E / 4570.3N, Peekskill quadrangle.]

Orthopyroxene-bearing gabbro (norite) of Pluton V of the Cortlandt Complex here exhibits poikiloblasts of primary igneous kaersutitic amphibole ranging from 1-4 cm and averaging 2 cm in size. Within the norite occurs an elongate xenolith of tightly folded, contact metamorphosed Inwood (Wappinger equivalent) Marble.

STOP 8 - Type locality of Annsville Phyllite, Annsville, NY. [UTM Coordinates: 590.00E / 4573.19N, Peekskill quadrangle.]

This large roadcut exposes the Annsville Phyllite of Medial Ordovician age. We are in the town of Annsville and you are therefore in the type locality of this distinctive, black to dark-gray carbonaceous rock unit. Here, the lithology holds up a ridge bifurcated by Sprout Brook to the west and Peekskill Hollow Creek to the east. The cut exposes a rather monotonous, steeply dipping and highly cleaved sequence of uniform micaceous slate and lustrous, flaggy phyllite that extends northeastward toward Gallows Hill. CM argues that the presence of a steep down-dip intersection lineation and mineral streaking within the slaty cleavage indicates the presence of non-obvious intrafolial F₁ isoclinal folds that are probably best observed on top of the outcrop. In a few places isoclinal folds (probably F₂ or second generation) of thin quartz veins occur showing SE plunges. There is a sub-horizontal rock cleavage that is axial planar to kink bands and crenulations of the slaty cleavage and late joints that trend N28°E, 32°NW. The overall structure of the ridge is probably that of a synform overturned to the northwest.

STOP 9 - Poughquag Quartzite. (Optional, time permitting). [UTM Coordinates: 589.82E / 4559.9N, Peekskill quadrangle.]

Here, hopefully up-wind from the sewage treatment plant on the day of our trip, note the gently east-dipping thinly laminated bedding and sub-parallel foliation of the Poughquag Quartzite. The quartzite is of Early Cambrian age; it represents the basal part of the Sauk Sequence (deposits of former Early Paleozoic shelf). The Poughquag is a dense, hard, fine- to medium-textured quartzite that ranges in color from white to tan and brown to reddish (Schaffel, 1958). Local conglomeratic facies contain distinctive bluish quartz pebbles. As such, this outcrop belt of the Poughquag (and perhaps its northern correlative--the Cheshire Quartzite) are the probable parents for many of the resistant quartzite (+/- hematite stained) boulders that we found had been eroded from the tills at Croton Point Park.

1) To familiarize you with the variety and depositional history of the Silurian and Devonian strata of Layer III in New York State.

2) To examine and understand the northeasterly stratigraphic thinning and ultimate pinchout of these units in comparison to their temporal equivalents toward the southwest.

3) To get close and personal with anticlines, synclines, faults, and other geologic structures.

4) To examine and use in the determination of topping direction, sedimentary structures such as graded beds, ripple marks, cross beds, etc.

5) To examine and marvel at the Taconic unconformity at a number of places.

6) To observe and hopefully, collect fossils from the Siluro-Devonian strata.

7) To perform a series of exercises in geologic mapping and compass techniques.

8) To test, in the field, the application of the PAC hypothesis in understanding sedimentation.

9) To witness, in a 350-million-year flashback, the depositional history of the Lower Paleozoic strata and to note the change from marine- to non-marine sedimentary successions, and,

10) To visit all of our intended field trip stops (Fat Chance! But 9 out of 10 isn't bad).

STOP 1a - Proterozoic metasedimentary, granitic-, and dioritic gneiss of the Hudson Highlands, Sloatsburg Service area, I-87N. [UTM Coordinates: 568.1E / 4556.05N, Sloatsburg quadrangle.]

Behind the Thruway rest facilities and OTR pit stop, Grenville-aged (1.1 billion year old) granitic gneisses of the Hudson Highlands complex crop out. Here, the Grenville basement is well-exposed along the east wall of the Sloatsburg Service area of I-87N as hornblende-bearing granitic gneisses that are locally migmatitic (show evidence of partial melting) and cut by numerous faults (with at least three different orientations), as well as a series of joints. The intersection of joints and faults create blocs that are generally rust colored because of the weathering of iron-bearing sulphide minerals such as pyrite. The faults are distinguished from joints in that they show visible offset and often show slickensides (mineralized gouge developed along the bounding rock surfaces). The joints are often tight (and, by definition, show little or no displacement) but are commonly mineralized by fine intergrowths of mica, zeolite minerals, epidote, calcite, quartz, and pyrite, or mixtures of the above.

Interlayered within the main mass of the granitic gneiss are layers and lenses of dark-colored amphibolite and light green diopsidic calc-silicate rock. The probable parent rock (protolith) of the granitic gneisses are granite plutons, and/or quite possibly volcanic ash deposits and/or feldspar-rich greywackes. The calc-silicate rocks began life as carbonate-rich sediments and amphibolites are probably metamorphosed basaltic extrusives or calcareous, iron-rich (ferruginous) shales. As such, the overall stratigraphic sequence idealizes our concept of pre-metamorphic continental crustal rock and overlying shallow- water sediment of the cratonic realm.

In the center of the exposure note the steep post-Grenville mafic dike that contains no vestige of metamorphic fabric but is cut by the same brittle features found throughout. Based on regional mapping, these mafic dikes are either lamprophyres of Ordovician age (related to the Taconic Orogeny) or basaltic dikes of Mesozoic age (related to rifting and development of the Newark Basin).

Pull-Over STOP 1b - Carbonate rocks of the Sauk Sequence cut by mafic dikes on Route I-87N (10.2 miles north of STOP 1). [UTM Coordinates: 571.8E / 4570.3N, Monroe quadrangle.]

State law precludes stopping to look at rocks on I-87 so this pull-over stop will be discussed in the van - eyes right! After numerous miles of Proterozoic gneiss exposure on I-87N we have now passed into a major graben that exposes Cambrian to Ordovician limestone and dolostone. Here the well-layered, whitish to tan-weathering dolostone dips to the east with a strike parallel to the highway. Of additional interest here is the tan-weathering ferroan dolomite, algal laminae, and a mafic dikes that cut angularly across the bedding of the carbonate rock and in places include angular xenoliths of the carbonate host rock.

STOP 2 - Devonian Sandstones at Highland Mills (former) Railroad Station. [UTM Coordinates: 573.5E / 4577.3N, Popolopen Lake quadrangle.]

Watch for trains here as they do come by! The belt of outcrop here is the NW-dipping southeast limb of a syncline consisting of steeply dipping Devonian clastic strata of the Highland Mills Member of the Esopus Formation. Note the view to the north of Schunnemunk Mountain which occupies the core of a large synclinal structure. The topographic map shows evidence of strike ridge with a NE strike and vertical to very steep NW dip. The ridge is underlain by lower Silurian, here the Green Pond Conglomerate, overlain by redbeds (Longwood Shale = equivalent of High Falls Shale to be seen later). The things we would like to do here is show you how to measure strike and dip, identify tops and bottoms of beds, hummocky strata, and to find some representative Devonian fossils.

The rocks here consist of interbedded highly laminated sandstones and shales with individual layers 0.5 to 1.0 m thick. Local 3-4 cm layers of black shale are present. The laminated texture of the sandstones suggest that deposition took place under the influence of moderate to strong currents. The interbedded shales indicate periods of quiescent deposition. The fossils found here include various types of brachiopods, gastropods, pelecypods, and trilobites, preserved as molds and casts; original skeletal carbonate has generally been dissolved. The layers show shell hash, probably concentrated during storms. Loose slab shows symmetrical wave-generated ripples; look to see if these can be found in situ. At the N end of exposure, where the burrow marks are so prominent, the overlying massive sandstone shows spheroidal weathering as a result of weathering along right-angle corners of joint intersections.

STOP 3 - Ordovician graywackes of the Tippecanoe Sequence under Thruway Bridge. [UTM Coordinates: 578.21E / 4629.7N, Rosendale quadrangle.]

Exposed under the Thruway overpass are interbedded, cross laminated Ordovician graywacke and black shale and siltstone exposed in an open syncline. Beneath the Thruway bridge, strata are nearly horizontal and wacke layers are over a meter thick. West of the bridge, the average thickness of the wacke layers are 5 to 15 cm and they are internally laminated indicating deposition during strong currents. They exhibit graded bedding, irregular bases, rip-up clasts, flame structure, and sole marks that together indicate that tops are up. Cross strata indicate current flow towards the SW. Locally the wackes contain pebbles of Sauk carbonate and black chert, black argillite, and brachiopod fossils. The brachiopods show up as "holes" in the graywacke layers and as these are grain-flow deposits, the fossils have been transported and would give a maximum age for the layer.

Time permitting, we may continue eastward on Route 213 to examine a thick-bedded portion of the Tippecanoe sequence exposed on the above the Dashville hydroelectric plant along the Wallkill river. Here, many spectacular anticlines and synclines expose Tippecanoe rocks. Faulting and imbrication and minor folding of the wacke layers was produced by layer-parallel shortening during large-scale folding when the incompetent shaly interbeds flowed and the sandy beds broke. A steep fault is exposed at the east end of the exposure. Note the calcite and quartz veining and the abrupt change in orientation east of the fault. Glacial scratches here are oriented N5°W and an erratic of Helderbergian limestone looms on the hillside above the fault.

STOP 4 - Siluro-Devonian Section and Rosendale Quarry at Tillson. [UTM Coordinates: 576.7E / 4631.7N, Rosendale quadrangle.]

The strata exposed here are quite thin but consist of a northward-topping sequence of Shawangunk Conglomerate (L. Sil.), overlain by the High Falls Shale, Binnewater Sandstone, and overlying cementstone carbonates. Farther ahead in the woods, the Siluro-Devonian succession crops out.

From the base upward, the units include the Shawangunk Conglomerate near the Taconic unconformity. The actual contact is not visible here (we might dig a little during the trip). The Shawangunk Conglomerate is in sharp contact at top with an overlying silty unit, the High Falls "Shale". The High Falls is not too well exposed and is about 6 m thick behind the bushes. Some reddish layers occur but bedding is obscure as the siltstone breaks into irregular chips. Farther along the road, is a good exposure of the top of the High Falls and base of the overlying Binnewater Sandstone. The Binnewater consists of interlayerd dolomitic carbonates and gray quartzose sandstones, in layers 10 to 15 cm thick. In the sandstones, are wave-generated oscillatory ripples, ripple cross strata, and possible hummocks.

Walk to end of exposure; find trail on R at start of metal guard rail. Continue along trail to exposure in woods to R and beware of poison ivy. Look for two pillars and entrance to former cement mine, now flooded. It is possible that the Wilbur Limestone occurs in this covered interval. The next rock unit exposed is the Rosendale Dolostone, the brownish-weathering rock found in the bottoms of the pillars. Cementstones were quarried because the dolomitic layers contain just the right amount of quartz silt to make a cement when roasted. These formed the basis of the Rosendale cement business of the 19th century (see historical marker in village of Rosendale).

STOP 5 - Faulted Shawangunk Conglomerate in High Falls village. [UTM Coordinates: 572.6E / 4630.65N, Rosendale quadrangle.]

This stop is in two parts separated by a buried (inferred) fault. Part 1 is found to the E, opposite the High Falls Motel (CM, but not George Washington, slept here on the eve of his first undergraduate field trip with Drs. Jack Fagan and Sy Schaffel of CCNY in 1968). Here occurs Shawangunk, about 6 m thick, with no top or bottom exposed. The conglomerate and silica-cemented sandstone dips 13°E and exhibits planar cross strata that show updip transport direction. Two sets of slickensides are found at the western edge of the exposure: (1) parallel to bedding, and (2) steep, with sense of motion E side up.

Part 2 to the W is across a fault with overlying red High Falls Shale preserved on top of the Shawangunk. The conglomerate here is about 8 to 10 m thick with base not exposed, in the crest of a broad anticline that trends N-S. The features here include shaly interbeds, possible hummocks, and cross beds. It is unusual to find this much Shawangunk without high relief. A possible explanation is that this is the crest of an anticline only recently exposed and not yet elevated with respect to surrounding rocks. Between the two outcrops is a fault, trending NS and with E side up to bring Shawangunk up to level of High Falls Shale Formation. In the covered interval, Ordovician shale may be faulted against High Falls Formation.

STOP 6 - Binnewater Sandstone and High Falls Shale in east-vergent monoclinal flexure, High Falls hydroelectric station. [UTM Coordinates: 571.91E / 4630.95N, Mohonk Lake quadrangle.]

Walk through fence maze to the fence nearest the falls. This area has been restored and made available by Central Hudson Gas and Electric Corp and the High Falls Civic Association. At the upper Falls, the lip is composed of the Rosendale Dolostone with Binnewater Sandstone just below, both dipping NW (upstream). Beneath the Binnewater is the High Falls Shale with cuts here on the N side of creek marking the type locality. Walk down blacktop path to lower level. Exposed on R is cliff of Binnewater Sandstone, with dip to NW. Near the bottom is the contact with the High Falls Shale.

A noteworthy feature of the asymmetric fold on opposite bank of creek is that the fold axial surface dips NW (opposite to the SE dip of most Appalachian folds). CM and JES suggest that this anticline has developed over a ramp up to a bedding-plane thrust that duplicates the Rosendale-Binnewater-High Falls succession here.

STOP 7 - Williams Lake Hotel transect through plunging folds. [UTM Coordinates: 576.3E / 4535.0N, Rosendale quadrangle.]

This is a free-form stop with no notes, but we will traverse the old railroad bed to map the lithology and structure of the rocks exposed here. The section starts with Shawangunk Conglomerate and proceeds upward through the High Falls Shale, Binnewater Sandstone, Rosendale Dolostone, Glasco Limestone, Whiteport Dolostone, and Manlius Formation. Note that this area marks the northernmost exposure of the Shawangunk which pinches out somewhere between the Fifth and Fourth Binnewater Lakes. We will examine many geologic features, including sedimentary structures, bedding-plane thrusts, bedding-cleavage relationships, and folds and you will be rewarded with a lovely trip through the plunging folds (literally). We will walk up section into the Helderbergian limestones which you will see in more detail tomorrow.

STOP 8 - Mount Marion Formation on US Route 209, near Sawkill Road. [UTM Coordinates: 581.25E / 4647.15N, Kingston West quadrangle.]

The Mount Marion Formation is exposed here and consists of turbidites with individual beds 20 to 30 cm thick. They are interspersed in a predominantly black siltstone/shale succession. A spectacular repetition of an individual bed, over 30 times, in slices 2 m long, occurs as stacked, imbricate slices, sandwiched between horizontal beds. CM noticed this at 55 MPH! Let's pace the current horizontal distance between the 30 slices and calculate the percent of layer-parallel shortening. We estimate roughly 300% shortening just within this one obvious thrust zone.

The main slip surface is subhorizontal and disappears within bedding. Slabs are sheared along individual imbricate thrusts. Many of the slabs terminate in lenticular tips which we view as "tectonic" with a capital T. Earlier investigators have suggested soft-sediment deformation for this exposure. Rather we view the lenticular ends the result of mechanical slivering. Many angular shards of wacke floating in the weaker shaly matrix originated from the larger slabs of wacke. Overall, the movement sense is right-lateral slip with travel toward the west. As such, this small exposure is a microcosm of the entire Valley and Ridge Province as deformed during the terminal stage of the Appalachian orogeny.

The Mount Marion is equivalent to the Lower Bellvale Formation of the Monroe area of New York. It is the highest marine unit in the Appalachian Devonian and also the highest marine formation in Devonian. From here on up section there are no more carbonates. You might say we have just made a sudden withdrawal from the carbonate bank.

STOP 9 - Taconic Unconformity with Silurian Rondout Formation on Ordovician (Tippecanoe) Siltsone, NY 32, East Kingston. [UTM Coordinates: 585.1E / 4646.2N, Kingston East quadrangle.]

The two main features to be seen here are the Taconian unconformity and the Binnewater and Rondout strata that immediately overlie it. Notice the characteristics and attitude of the Ordovician strata (dominantly siltstones) which dip more gently than the overlying Rondout strata. Here the Binnewater is only 0.25 m thick and the High Falls and Shawangunk formations are totally missing.

The rocks are tilted due to folding and although we do not see obvious folds a prominent pressure solution cleavage is developed in the Silurian strata. It passes through and beneath the unconformity and is sub-parallel to the Ordovician slaty cleavage. Thus, the Ordovician strata are cut by two cleavages (note the wedge-like appearance of the cleavage fragments) but the Silurian only possesses one obvious deformational fabric. If the Rondout strata are rotated back to their initial horizontal positions, the attitude of the Ordovician strata would be subhorizontal. Note that the pre-Silurian (Taconic) Ordovician cleavage (after unfolding of the Silurian strata) would dip moderately steep toward the SW! Thus, we must be at the hinge area of an eroded Ordovician fold and, as such, the unconformity here might be a disconformity.

STOP 10 - Taconic Unconformity and bedding-plane thrusts in Helderbergian carbonates, NY 32, East Kingston. [UTM Coordinates: 585.1E / 4646.82N, Kingston East quadrangle.]

At Stop 10, we see all parts of the Rondout Formation, with base resting on the Taconian unconformity, as at Stop 9, but with the added factor of repetition of the Siluro-Devonian strata along a number of bedding-plane thrusts. We will work our way along the large rock face beginning at the N end with the Ordovician strata. Steeply north-dipping extension fractures (related to the ramp-like thrusts) are lined with calcite. We note minor normal reactivation of some of the bedding plane thrusts based on left-lateral offset of steep, post-thrust calcite veins.

STOP 11 - Helderberg Strata on N side NY Route 199, on W approach to Kingston-Rhinecliff Bridge. [UTM Coordinates: 585.05E / 4647.5N, Kingston East quadrangle.]

At this stop, the bottom of the Helderberg carbonates is not visible, but we can see the upper part of the Manlius (Thacher Member) and all three units of the lower fining-upward cycle of Coeymans (Ravena Member)-Kalkberg (lower Hannacroix and upper Broncks Lake members)-New Scotland. See what you can find in the way of fossils here. The best specimens may not be in the fresh bedrock, that breaks so irregularly, but in the weathered blocks at the top of the ridge. Study of the molds and casts in fine-textured rocks can yield nearly as much detail as study of fossils in which the original skeletal material is intact.

STOP 12 - Anticlinal Fold of Helderberg Strata, on N side of NY Route 199, W approach to Kingston-Rhinecliff Bridge. [UTM Coordinates: 584.75E / 4647.38N, Kingston East quadrangle.]

This small anticline brings up the strata of the upper fining-upward cycle, the Becraft-Alsen-Port Ewen beds. The anticline is separated from the strata at Stop 11 by a fault that follows the low covered interval between the two ridges where rock is exposed along the highway. Notice the comparable relationships of a coarse, gray, skeletal limestone without much silt and lacking chert in the basal unit (Coeymans and Becraft). This grades upward into a siltier rock containing chert (Kalkberg and Alsen). At the top, the chert vanishes and the rock is a shaly calcareous siltstone (New Scotland-Port Ewen).

STOP 13 - Mount Marion Formation, New Cut on NY Route 32, Quarryville (N of Mt. Airy). [UTM Coordinates: 584.0E / 4363.15N, Saugerties quadrangle.]

This cut exposes the same formation we examined at Stop 8, a deep-water marine deposit consisting of dark gray to black shale, siltstone, and sandstone somewhat resembling the Ordovician flysch. Very little shale is exposed at the W end of the exposure. Rather, non-graded and non-laminated massive sandstone and siltstone occurs. Note the rounded, dense concretions which consist of pyrite, siderite, and possibly barite. Look for Devonian brachiopods in the sandy layers. Check closely to see if any bedding-plane thrust faults repeat any layers, as observed at Stop 8.

STOP 14 - Ashokan Formation, NY Route 32, W of Quarryville. [UTM Coordinates: 583.13E / 4663.6N, Saugerties quadrangle.]

The Ashokan Formation is the formation quarried as New York blue stone and is used for paving slabs on sidewalks. Notice the well-developed large-scale cross strata that show stream flow toward the west. JES thinks that the Mount Marion-Ashokan combination is equivalent to the Bellvale Formation of the Schunnemunk-Green Pond belt, with lower Bellvale equal to Mount Marion and upper Bellvale, to the Ashokan.

STOP 15a - Catskill Redbeds and Conglomerate along North Lake Escarpment, Haines Falls, New York. [UTM Coordinates: 580.02E / 4672.92N, Kaaterskill quadrangle.]

The Catskills are a thick sequence of fan- and delta deposits that show sedimentary structures indicating an eastward source. The horizontal layering of the Catskills are quite obvious (even from a distance) and the rocks vary from red shales to siltstones and sandstones to very coarse conglomerates. The red color may make you think of the Newark Series but, in fact, these rocks are much older (middle Devonian) despite the fact that they appear similar. We hope you noted the impressive thickness of the Catskill sequence as we drove up the Catskill Front from Stop 14.

The Catskill Mountains are mountains because they are composed of resistant strata containing sandstone and conglomerate. These are much more difficult to erode than the soft shales and limestones in the Hudson Valley. The section of strata along Route 23A consists of 2,000 feet of coarse river deposits and also contains successive intervals of fine grained floodplain deposits (red siltstone and mudstone) - all characteristics of the non-marine portion of the Catskill Delta. The source area for the cobbles is clearly toward the east - any ideas on where they came from? Try to imagine the ancient landscape as mirror image of the modern Rockies and Great Plains with mountains to the east (now eroded hills of the Taconics and Berkshires) with an alluvial apron sloping westward as far as present day Ohio. The continentally-derived fans gave way westward to shallow marine seas into western Pennsylvania and Ohio where thinner Devonian marine facies are found. The shoreline prograded toward the west as the abundance of sediment pushed the seas toward the interior of Devonian North America.

Pull-Over STOP 15b. [UTM Coordinates: 589.27E / 4672.20N, Cementon quadrangle.]

Note the open anticline on the right (south) side of the road at the end of the unfinished (abandoned?) Thruway exit ramp. Here, The sequence, from top to bottom, is the Esopus Shale, Glenarie Limestone, and Port Ewen Limestone. Note the well developed subvertical slaty cleavage in the Esopus and the intricate folds in the Glenarie within the disrupted bedding. Note the contrast in structural style of the three units, a function of their composition and layering characteristics.

STOP 16 - Taconic Unconformity and overlying Rondout and Helderbergian carbonates, N side of exit ramp from new location of NY Route 23 from Rip Van Winkle Bridge to old NY Route 23, Jefferson Heights, Catskill. [UTM Coordinates: 591.9E / 4676.6N, Cementon quadrangle.]

Here, the Rondout Formation and Helderbergian carbonate succession are in marked steeply-dipping unconformity with underlying Ordovician graywackes. The Rondout Formation consists of about 1 m of Rosendale Dolostone with a thin basal sandstone (Binnewater?) resting on the steeply dipping Ordovician Tippecanoe sequence. Overlying the Rosendale is roughly 10 cm of limestone that is probably the feather edge of the Glasco Limestone, followed by the Whiteport Dolostone. Thrust faults occur above the Whiteport in a chaotic zone with right-lateral shear sense, characterized by intrafolial isoclinal folds and then the chaotic sequence is capped by the highly laminated Manlius (Helderbergian) Limestone follwed by the Coeymans and Kalkberg limestones. Note that the Shawangunk, High Falls, Binnewater, Wilbur sequence is absent and that what is left of the Silurian is exceedingly thin.

STOP 17 - Taconic Unconformity at SW corner of Becraft Mountain, S of Hudson, NY. [UTM Coordinates: 599.75E / 4673.42N, Hudson South quadrangle.]

Only a few places exist where budding geologists can place their fingers on the pulse of a former orogeny. In this exposure, the Silurian Rondout Formation rests with angular unconformity on cherts of the Mount Merino Formation (Middle Ordovician Tippecanoe Sequence). The surface of unconformity is quite irregular and the angular discordance between beds above and below is small, perhaps as a result of minor thrust faulting at the Rondout-Mount Merino contact. Within the base of the brown-weathering Roundout (a silty dolostone), however, clasts of black Mount Merino chert and quartz occur. This would be expected if the contact is indeed one of unconformity!

The Rondout is overlain by highly laminated, whitish rocks of the Manlius Formation, but the Rondout appears again above the Manlius. What gives? Bedding thrusts occur within the Rondout and overlying Manlius. The field exposure shows the bedding thrusts (the lower one outlined by a calcite vein) which imbricate the Siluro-Devonian carbonates above the surface of unconformity with local folding ("rolling") of the Rondout. Again, clear evidence for significant post-Taconic, low-angle thrusting! Toward the south, the Manlius dips below the calc-arenites of the overlying Coeymans Formation and possibly massive limestones of the Kalkberg and New Scotland formations but significant complications are present.

1) To drive across and observe the Mesozoic rocks of the Newark Basin at 55 mph.

2) To examine the Cambro-Ordovician shelf deposits Kittitinny dolomitic carbonates of Passive Margin I.

3) To examine evidence for glaciation and glacial deposition in the Wallkill valley and discuss the drainage history of the region.

4) To contrast and compare the Paleozoic and Proterozoic marble units and to discuss their paleoenvironments.

5) To examine the Proterozoic rocks paying particular attention to the host rock for the Franklin-Sterling Hill orebodies and to discuss their genesis.

6) To visit the world-famous Sterling Hill Mine site and the Franklin Mineral Museum for guided tours and, time permitting collecting, and,

7) To get close and personal with folds, faults, and surfaces of unconformity.

STOP 1 - Folded- and Faulted Sauk Sequence Carbonates (Cambro-Ordovician) in new cuts on NJ Route 15. [UTM Coordinates: 530.7E / 4544.5N, Newton East quadrangle.]

New road cuts are the stuff geologist's dreams are made of. Here, in freshly opened roadcuts for new ramps on NJ 15, Paleozoic carbonate rocks (the blue limestone of the older literature or Kittatinny Dolostone and Limestone of modern usage) are exposed. At the extreme south end of the exposure note the well-bedded nearly vertical layers with discontinuous black chert seams 3- to 4 cm thick. The bedding is subparallel to subvertical dissolution cleavage (stylolites) that indicate, along with the steep orientation, that some degree of deformation has affected these strata. These features are cut by subhorizontal cross fractures filled with calcite.

Grading northward, underneath the overpass, the carbonates are more massive. Here, crenulate folds with subhorizontal axial surfaces deform the dissolution cleavage and sedimentary layering. These second-generation (F₂) folds are geometrically, and possibly temporally, related to the calcite-filled fractures noted above. North of the overpass significant zones of breccia are present; clast sizes range from l cm to 1 m and many show significant internal cracking suggesting high pore pressures during brecciation of consolidated rock. In addition, some of the boulders are breccias within themselves! We interpret that most of the brecciation was stratigraphic (sinkhole- and collapse breccias) and compare them