NYSGA 1976
FIELD GUIDE BOOK
New York State Geological Association
48th Annual Meeting
VASSAR COLLEGE POUGHKEEPSIE, NEW YORK OCTOBER 15-16, 1976
The organizer of the field trips described in this volume, and of the meeting at which they were given, is
Professor John H. Johnsen, Chairman
Department of Geology & Geography
Vassar College
Poughkeepsie, New York 12601
Copies of this guidebook may be purchased the Executive Secretary of the New York State Geological Association: Dr. Daniel F. Merriam, Chairman Department of Geology, Syracuse University, Syracuse New York 13210.
Frontispiece -A. Scott Warthin Jr., Professor Emeritus of Geology, Vassar College, dean of Hudson Valley Geologists and expert on Dutchess County geology, examining block of Wappinger dolostone in deformed Snake Hill Shale, visible between Stops 3 and 4 on Trip 8-6, south side of Spackenkill Road near Cedar Valley Road.
Photograph by Donald W. Fisher, 1975.
PREFACE
The area surrounding Vassar College provides a wealth of material for the geoscientist. It's classic ground in the study of geology -the Taconics, Hudson Highlands, Shawangunks, Catskills and the Hudson Valley each provide wonderful and exciting outdoor classrooms. Because most major rock types lie within one or more of these areas, it was possible to schedule a number of excursions into igneous, sedimentary and metamorphic terrains which exhibit simple to intensely deformed structures as well as geologically-oriented trips related to recent environmental concerns in part brought on by the presence of these structures. Each of the leaders invited to participate is either involved in current field research or has had a great deal of recent field experience within the area of his trip so that much new significant data heretofore unpublished are made available in this guidebook. The field program is sufficiently diverse in locale and content to provide something of interest for everyone.
To celebrate the Bicentennial of our country, we depart from tradition by offering a limited enrollment extra-cost trip on the Hudson River from New York City to Poughkeepsie on the first day of the meeting to view the geology along its east and west banks and to learn something of the colonial and revolutionary history that was made along its course and, on the final day, a walking trip through historic Fishkill, New York. A separate guidebook has been prepared for the participants of the river trip, but a limited number will be available for sale. In addition, the Lamont-Doherty Geological Observatory at Palisades, New York, will host an open house on the first day of the meeting to provide an opportunity for members of the New York State Geological Association to tour the facilities and meet with a number of the scientists conducting research there.
Lack of secretarial assistance and increased costs made it impossible for articles to be retyped on the same machine. By prior mutual consent, each author agreed to use one of several similar type styles and to review their manuscripts before submission. No editorial changes were made.
The Editor wishes to express his thanks, on behalf of the NYSGA, to Vassar College for serving as host to its 48th Annual meeting, to each of the authors who graciously accepted full responsibility for organizing and leading his trip, to A. Scott Warthin Jr., who ably took over the reins for me during the summer of 1976 while I was on the other side of the world and to those colleagues and majors in my department that gave so generously of their time.
Welcome to Vassar College and the historic Mid-Hudson Valley. We hope you thoroughly enjoy your brief study of this region.
John H. Johnsen Editor

B1: STRUCTURE, PETROLOGY ANO GEOCHRONOLOGY OF THE PRECAMBRIAN ROCKS IN THE CENTRAL HUDSON HIGHLANDS
Henry L. Helenek
Bradley University
Peoria, Illinois 61625
Douglas Mose
George Mason University
Fairfax, Virginia 22030
INTRODUCTION
Recent studies in the New York portion of the Reading Prong indicate that the Hudson Highlands may consist of two terranes of Precambrian rock (Harwood and Zietz, 1974; Hall et al., 1975). A western terrane consists of charnockitic gneisses and paragneiss intruded by syntectonic granitoid plutons. An eastern terrane consists of quartzo-feldspathic gneisses having lithic and structural similarities with the Fordham gneiss immediately to the south in Westchester County (Hall et al., 1975). Fundamental differences in lithology, structure, geochronology and magnetic signature have been summarized by Harwood and Zietz (1974) and Hall et al. (1975). Although the position and nature of the contact separating the two terranes remains problematical, an approximate boundary may be placed in the vicinity of the Ramapo-Canopus fault system in the Hudson Highlands. Detailed study is needed to establish the relationship between the two suites of rock. The purpose of this field trip is to examine the structure, petrology and geochronology of Precambrian rocks at select sites in both terranes. The Lake Carmel area in the eastern Highlands (stops 1 and 2) and the West Point area in the western Highlands (stops 3, 4, 5, 6, 7, 8) have been chosen for this purpose.

B1: STRUCTURE, PETROLOGY ANO GEOCHRONOLOGY OF THE PRECAMBRIAN ROCKS IN THE CENTRAL HUDSON HIGHLANDS

Exposures of the Wappinger Group are seen on both sides of the road.

Normanskill formation and Austin Glen formation
This low-lying area of sparse outcrop is underlain by autochthonous Middle Ordovician clastic rocks (Normanskill formation and Austin Glen formation).

Austin Glen formation on left
Exposures of autochthonous Middle Ordovician rocks (Austin Glen formation) on the left side of Route 9.

Austin Glen formation on right
Exposures of autochthonous Middle Ordovician clastic rocks (Austin Glen formation) on right side of Route 9

Glenham gneiss belt.
Exposures of sheared Precambrian gneisses and the Wappinger Group along both sides of Route 9.

Precambrian gneiss
To the left is Honness Mtn. Exposures of Precambrian gneiss.

Poughquag quartzite
Toward the left in the westbound lane of I-84, are exposures of Poughquag quartzite.

Exposures of lower members of the Wappinger Group on both sides of I84.

Gently folded syncline on left Highlands on right
Gently folded syncline in the Wappinger Group on the left (north) side of 1-84. The Hudson Highlands are seen to the right (south).

Exposures of lower members of the Wappinger Group.

Ramapo fault
The prominent valley to the right (south) is an extension of the Ramapo fault through the Hudson Highlands.

Large exposures of Precambrian gneiss.
Biotite granitic gneiss predominates with subordinate amphibolite and hornblende biotite granite gneiss. Rocks have varying degrees of cataclastic deformation. Minerals are partially altered. Toward the eastern end of the exposure is in-folded Poughquag quartzite.

Large exposures of Precambrian gneiss.
Predominant rocks are biotite-quartz-plagioclase gneiss and quartz-plagioclase leucogneiss with subordinate amphibolite, biotite-hornblende-quartz-plagioclase gneiss and pyroxenite. All minerals are partially altered and replacement textures common.

Large exposures of Precambrian gneiss.

View of Hudson Valley
Toward the left (northwest) is a spectacular view of the Hudson Valley.

Large exposure of Precambrian gneiss.
Precambrian rocks from this point to stop 1 consist of biotite-quartz plagioclase gneiss, biotite-hornblende-quartz-plagioclase gneiss, amphibolite and biotite-muscovite-quartz-plagioclase gneiss.

Sampling locality for Rb/Sr whole rock dating
Large exposure of light gray, biotite-muscovite-quartz-plagioclase gneiss. Sampling locality for Rb/Sr whole rock dating (1296 ± 77 m.y.).

Large road cut of Precambrian amphibolite.

STOP 1. Mill Pond Garden Center.
(No hammers, please!)
Exposure of light gray, biotite-muscovite-quartz-plagioclase gneiss. This foliated gneiss is one of the most important lithologies in the eastern Hudson Highlands. The exposure seen here is on strike with the large roadcut of light gray gneiss on I-84. In the I-84 outcrop. the biotite-muscovite-quartz-plagioclase gneiss contains bands consisting of biotite-actinolite-plagioclase gneiss. Foliation trends about N40°E and is almost vertical. The light gray, biotite-muscovite gneiss is among the oldest rocks found in the Hudson Highlands and yielded a Rb/Sr whole rock age of 1296 ± 77 m.y, with an initial 87Sr/ 86Sr ratio of 0.7032 ±0.0005.

Exposures of Precambrian rock.

Walloomsac formation
Exposures of metamorphosed Middle Ordovician clastic rocks (Walloomsac formation).

STOP 2. Forest Haven Apartments.
A short traverse will be made through the upper pЄ ga unit and the lower pЄ lg unit.(No hammers, please!)
Station A. pЄ lg unit. Exposures of layered, medium-grained, mesocratic biotite hornblende-quartz-plagioclase gneiss. Prominent F2-folds have axial planes trending about N40°E, 60°S. Fold axes plunge about S70°E at 60° but marked variability from this direction is noted. Abundant crenulation folds are related to F2-folds.
Station B. pЄ ga unit. Leucocratic granitic gneiss forms large domical exposures. Amphibolite with calc-silicate nodules defines a large F2-fold.
Station C. pЄ lg unit. Exposures of layered biotite-hornblende-quartz-plagioclase gneiss. Prominent F2-folds have axial planes oriented N-S, 55°E; folds plunge N58°E at 34°. The change in orientation of F2-axial planes from station A is a result of F3 folding.

Rb/Sr whole rock age of 1308
About one mile to the south, samples of a granite gneiss yielded a Rb/Sr whole rock age of 1308 ±41 m.y.

To the right (south) is the Tilly Foster Mine.

Large roadcut to the right
Geology of the large roadcut to the right described by Fenster and Brock, 1975.

Large preCambrian exposures
Large exposures of the pЄ q unit and the pЄ lg unit.

Large exposure
Large exposure of the pЄ ga unit. This roadcut is described in detail in Hall et al. (1975).

Contact between ga and am units
Exposures of the contact between the pЄ ga unit and the pЄ am unit.

Far lane has exposures of bg unit
To the left in the eastbound lane of 1-84 are exposures of the pЄ bg unit.

Whole Rock date 1296
Exposure on the left is a sampling locality for Rb/Sr whole rock dating (1296 ±77 m.y.) of the biotite-muscovite-quartz-plagioclase gneiss.

Whole rock age 1296
Exposure on the left is a sampling locality for Rb/Sr whole rock dating (1296 ±77 m.y.) of the biotite-muscovite-quartz-plagioclase gneiss.

Exposures of paragneiss on the right side of Route 301.

Entering the Ramapo-Canopus fault zone.
Note sheared rock on both sides of road.

Canopus Lake.
The Ramapo-Canopus fault roughly trends along the axis of the lake.

Whole rock age 914
Exposure on the right is a sampling locality for Rb/Sr whole rock dating (914 ±31 m.y.) of the Canada Hill granite.

Whole rock age 914
Exposure to the right of the road is sampling locality for Rb/Sr whole rock dating (914 ±31 m.y.) of the Canada Hill granite.

Site of the Robinson House on the left.
Site of the Robinson House on the left. Benedict Arnold secretly offered the British the surrender of West Point and settled the particulars in a midnight meeting with Major John Andre in the Robinson House on Sept. 21, 1780. Andre was captured two days later and hanged at Tappan, Oct. 2, 1780. Arnold made his escape to the British sloop, Vulture.

Prominent landform to the left is Sugarloaf Mountain.

Eastern anchor for chain across Hudson
Eastern anchor for the chain across the Hudson River which failed to prevent British ships from sailing up the Hudson River during the War of Independence.
2013: Historic marker here says "The first chain, planned to keep British ships from going up river anchored on shore below, was forced by the enemy, Oct. 7, 1777"

Bear Mountain and the Torne
The large mountain straight ahead and to the left is Bear Mountain. The prominent knob straight ahead and to the right is the Torne.

STOP 3. Bear Mountain.
Stop 3 is a short walk north of Bear Mountain Inn to the roadway north of Hessian Lake (Fig. 3). The exposures that will be studied at this locality are in Harriman State Park and regulations prohibit destruction of the environment in any way. (NO HAMMERING PLEASE!)
Several lithologies typical of the western Highlands terrane are seen in these exposures. These include the paragneiss (pЄ pg) with its associated amphibolite and rusty pyroxenic gneiss (pbЄ pga) and foliated hornblende granite (pЄ sk). Canada Hill granite (pЄ ch) cross-cuts structures in all three lithologies. These units form the lower limb of a reclined isoclinal F2 antiform (Ft. Montgomery antiform).
pЄ pg, pЄ ga and pЄ sk are folded into isoclinal digitations and compositional layering is completely transposed into an F1 axial planar foliation. F2-folds are locally similar in style and are usually more open than F1-isoclinal folds. Several minor F2-folds occur in the hornblende granite at this locality. A hornblende lineation best seen in the amphibolite (pbЄ ga) trends about N37°E at 37° and is parallel to fold axes of F2-folds. The broad curvature to the units in the Bear Mountain area seen on the map (Fig.3), is due to F3-folding. Fold axes of F3-folds plunge N50°E at 36° in this area.
The deformation seen in the hornblende granite at this locality is absent in the main mass (core) of hornblende granite at Bear Mountain. However. a strong hornblende lineation in the core granite parallels the hornblende lineation in the amphibolite (pЄ pga) of the paragneiss unit (pЄ pg). Since marginal gneissic facies of the hornblende granite locally possess secondary foliation related both to D1 and D2, the Bear Mountain pluton has been involved in all phases of deformation. The Rb/Sr whole rock age of 1086 m.y. and the U/Pb age of 1060 m.y. obtained from the lineated core facies of the pluton probably indicate the time of crystallization of residual melt in the Bear Mountain pluton. This would suggest that final crystallization of the hornblende granite was coeval with the termination of F2-folding in the West Point area.
The coarse-grained, leucocratic Canada Hill granite cross-cuts linear and planar structures in the granite-gneiss sequence and contains inclusions of pЄ sk and pЄ pga (the latter not seen in these exposures). In other localities where the hornblende granite and Canada Hill granite are in close proximity, the relationship between the two granites is at best equivocal. Field relationships seen at these exposures clearly demonstrate the crosscutting nature of the Canada Hill granite. This, combined with a Rb/Sr whole rock age of 914 m.y., supports the assignment of a post-Storm King age to the Canada Hill granite. The crystallization of Canada Hill granite represents the termination of Grenville activity in the Hudson Highlands.

Bridge over Popolopen Brook (also known as Hell Hole).

Fort Montgomery
To the right of the road is the site of Fort Montgomery, prominent in the American Revolution.

Canada Hill granite
Exposures of Canada Hill granite in the core of the Crystal Lake pluton.

Large exposure of hornblende granitic gneiss.
Large exposure on the left side of Route 9W is hornblende granitic gneiss. This is an extension of the Bear Mountain pluton and forms the core of the West Point antiform.

Core of the West Point antiform
On the left side of the road are exposures of paragneiss in contact with hornblende granitic gneiss in the core of the West Point antiform.

STOP 4. Northern margin of the Crystal Lake pluton.
The next two stops will illustrate field relationships between the paragneiss unit (pЄ pg) and the Canada Hill granite (pЄ ch) by taking a cross sectional traverse through the Crystal Lake pluton. Canada Hill granite is found in several zoned plutons restricted to the paragneiss unit, the largest of which is the Crystal Lake pluton. Stop 4 is located at the northern margin of the pluton; stop 5 is located in the core of the pluton. In traversing the Crystal Lake pluton from margin to core, we will proceed from non-migmatitic paragneiss, through a marginal zone of migmatite (metatexite of Mehnert, 1968) into a core of diatexite (a rock characterized by "complete or nearly complete melting no longer be distinguished", Mehnert, 1968, p. 253). The following lithologies make up the Crystal Lake pluton and its enclosing rocks:
Non-migmatitic paragneiss is an equigranular rock with a metamorphic fabric containing quartz, plagioclase feldspar, microcline, biotite and garnet. Quartz, microcline and plagioclase feldspar are present in about equal amounts.
Migmatite consists of leucosome and melanosome. Leucosome is a coarse-grained, inequigranular rock containing quartz, microcline, plagioclase feldspar and biotite with or without garnet. In mineralogy, leucosome is similar to diatexite. Melanosome is finer and more even grained than leucosome and consists of varying proportions of quartz, plagioclase feldspar, biotite, garnet and occasionally sillimanite. Alkali-feldspar is minor or absent.
Diatexite is a coarse-grained, inequigranular rock consisting of quartz, slightly perthitic microcline, plagioclase feldspar (calcic oligoclase) and varying amounts of garnet and biotite. Sphene and zircon are ubiquitous accessory minerals; sillimanite, graphite and tourmaline are rare. Two facies of diatexite occur in the Crystal Lake pluton: homophanous diatexite (a homogeneous granite) and schlieric diatexite (homogeneous granite with schlieren of restite). Alteration related to crystallization of diatexite resulted in the formation of secondary muscovite and epidote and the alteration of biotite.
The Q:Ab/Pl:Or and mineralogical ratios for these rocks are plotted in figure 5. The normative Q:Ab:Or ratio of diatexite lies in the field of igneous plutonic rocks containing 80% or more normative quartz-albite-orthoclase (Fig. SA). These data support a magmatic origin for the diatexite facies of the Canada Hill granite. The normative Q:Ab:Or ratio of leucosome in migmatite likewise lies in the field of magmatic rock. Mineralogical data for Canada Hill granite (diatexite), migmatite and non-migmatitic paragneiss are plotted in figures 5C and 5D. The composition of Canada Hill granite and leucosome is virtually identical. The homogenized composition of leucosome-melanosome pairs approximates the mineralogical composition of non-migmatitic paragneiss. These data indicate that non-migmatitic paragneiss represents paleosome from which migmatite and Canada Hill granite formed by anatexis.
Isotopic studies also support an anatectic origin for the Canada Hill granite. Paragneiss yielded a Rb/Sr whole rock age of 1139 m.y. with an initial 87Sr/86Sr ratio of 0.7067. The Canada Hill granite (diatexite) yielded an age of 914 m.y. and an initial ratio of 0.7193. The data also show that the average 87Rb/86Sr ratio of the paragneiss is 3.8. If the paragneiss remained a closed chemical system between 1139 m.y. and 914 m.y. ago, its average 87Sr/86Sr ratio would have ranged from 0.7067 to about 0.7118. A calculated ratio of about 0.718 is essentially the same (given the error) as 0.7193, the initial 87Sr/86Sr ratio of the 914 m.y. old Canada Hill granite. This indicates that the paragneiss anatectically yielded a granitic melt in an isotopically non-fractionating manner which crystallized at about 914 m.y. ago to form Canada Hill granite.
Station A. Leave the parking area and proceed to Route 970/Main St. Turn right onto Route 970/Main St. and walk to large outcrop of the non-migmatitic paragneiss on the east side of the road.
Proceed down Route 970/Main St. in the direction of the parking area. Continue south past Station Hill several hundred feet to Michel's Gift Shop. Bear left off Route 970/Main St. and proceed down gravel road passing through the nursery (this gravel road is known as Wood Lane). Proceed to the end of Wood Lane past three private houses to the large exposure overlooking the Hudson River.
Station B. Large exposure of migmatite and Canada Hill granite. No hammers, please!

STOP 5. Canada Hill granite (diatexite)
Large roadcut exposing the schlieric facies of Canada Hill diatexite.

Core of West Point Antiform
Hornblende granitic gneiss in the core of the West Point antiform is seen to the left.

On left is paragneiss
Large roadcut to the left is paragneiss (pЄ pg).

Hornblende quartz monzonitic gneiss
To the right is an exposure of a thin sheet of hornblende quartz monzonitic gneiss (pЄ sk).

STOP 6. Magnetite alaskite.
Magnetite alaskite (pЄ al) is a late to post-tectonic plutonic rock occupying a narrow fault-controlled valley between the Crows Nest antiform and West Point synform. Alaskite is a medium-to coarse-grained, massive rock consisting of quartz (21 %), white plagioclase feldspar (41 %), pink microcline (35%) and magnetite (3%). Secondary minerals include muscovite, sericite and opaque oxides. Inclusions of country rock and xenocrysts derived from the country rock are common in the marginal facies of the alaskite. Recrystallized biotite inherited from the adjacent paragneiss is seen in this exposure of alaskite. A fracture cleavage is commonly developed in alaskite.
The relationship of alaskite to other Highlands lithologies remains uncertain. While it intrudes pЄ qp, pЄ pg and pЄ sk. its relationship to Canada Hill granite is not at all clear. The fracture cleavage in the alaskite may be related either to D3 or to some post-D3 deformational event. The lack of any penetrative structures related to D1 and D2 however, indicates the alaskite was intruded late in the deformational history.

Charnockitic quartz-plagioclase gneisses
To the left are large exposures of charnockitic quartz-plagioclase gneisses (pЄ qp), Coarser grained, massive rock is the alaskite which intrudes the quartz-plagioclase gneisses.

STOP 7. Crows Nest Lookout.
View of the Hudson River. Constitution Island and the United States Military Academy at West Point. The ridge southwest (to the right) of the Military Academy is held up by a thin sheet of hornblende quartz monzonitic gneiss. The hornblende granitic gneisses are the most resistant of the Highlands lithologies to weathering and are the major ridge formers in the Hudson Highlands. The quartz monzonitic gneiss at West Point forms a prominent ridge which outlines the structure of the West Point antiform. The fold axis of this antiform plunges N36°E at 22°; the axial plane is oriented N30°E, 74°S. The valley at the base of the Crows Nest is underlain by magnetite a1askite.
The Crows Nest lookout is situated along the southeastern limb of the Crows Nest antiform. Exposures of hornblende quartz monzonitic gneiss surround the lookout. The foliation in the gneiss is an F2 axial planar foliation oriented N45°E. 70°N. This foliation is continuous with a secondary foliation described by Murray (1965) in the crest of the Crows Nest antiform at Bull Hill. The hornblende quartz monzonitic gneiss forms the core of the Crows Nest structure and yielded an Rb/Sr whole rock age of 1169 m.y. The Crows Nest antiform plunges N43°E at 18°; the axial plane is oriented N60°E, 45°N. A prominent mineral lineation trends N40°E at 22°.
On the far side of Route 9W across from the lookout, a basic dike (orientation, N75°W, 62°S), about 90 feet thick, cuts the trend of the Crows Nest fold. Undeformed basic dikes are plentiful in the Highlands and parallel the dominant joint directions in the Highland gneisses. The majority of dikes are lamprophyric or diabasic; dioritic and andesitic as well as dikes consisting of syenite and quartz porphyry are less common. The age of these dikes is uncertain.

Core of the Crows Nest antiform
Exposures of hornblende quartz monzonitic gneiss in the core of the Crows Nest antiform.

To the left is a shear zone
To the left is a shear zone separating the Crows Nest block from the Storm King block.

Crest of Storm King Mountain
Large hill of bedrock to the right is the crest of Storm King Mountain (Butter Hill, elevation 1380 feet) underlain by hornblende granitic gneiss.

STOP 8. N. border fault of the Hudson Highlands.
Hornblende granite thrust adjacent to Ordovician clastic rocks. The trace of the fault on the map trends about N35°E. Berkey (1910), however, reported an orientation of N70°E, 45°S for the fault plane based on subsurface data obtained from the Catskill aqueduct project. The question arises as to whether the northern border fault is a high angle thrust fault or a low angle overthrust. A short distance southeast of this locality, Lowe (1958) reported overthrusting of Storm King granite over intensely crumpled Ordovician slaty shales. Further to the southeast (1400 feet southeast of this stop), Berkey (1910) noted that sheared hornblende granite was penetrated to a depth of 412 feet in a series of drill holes in Pagenstechers Gorge (ravine along Mountain Rd.). A tunnel bored across the Hudson River in 1912 from Storm King Mountain to Breakneck Ridge at a depth of 1100 feet and two inclined drill holes across the Hudson in the same area intersecting at a depth of about 1500 feet, both penetrated hornblende granite beneath the Hudson River (Kemp, 1912). These data would appear to suggest that the northern border fault of the Hudson Highlands is a high angle thrust fault with local overthrusting.

Museum of the Hudson Highlands.

Hornblende granite gneiss on both sides of the road.

Hills off to the right are the Hudson Highlands.

Washington's HQ to right
To the right is a road leading to Washington's headquarters in Newburgh (1782-83).

Cross the Beacon-Newburgh Bridge.
To the right (south) is a spectacular view of the northern passage of the Hudson Highlands. On the right is Storm King Mountain. On the left is Beacon Hill-Breakneck Ridge. The small island in the Hudson River is Pollepel Island.

Hornblende granite in the Glenham gneiss belt.

Wappinger Group with Balmville limestone
Exposure of the upper members of the Wappinger Group with conglomeratic Middle Ordovician Balmville limestone.

B2: STRUCTURAL GEOLOGY OF THE TACONIC UNCONFORMITY
Heinrich Toots
C. W. Post College
Long Island University
Greenvale, N.Y.
INTRODUCTION
The Hudson Valley is one of the classical areas of North American geology. One of its most prominent geological features is the Taconic unconformity separating the Ordovician and Cambrian sediments from the overlying Silurian and Devonian strata. The Taconic unconformity records the earlier of two (or possibly three) Paleozoic orogenies in the Hudson Valley. The Taconic unconformity has been known since the first half of the nineteenth century and its significance for stratigraphy and the geologic history of eastern North America has been discussed by many authors (Davis, 1883a, Schuchert and Longwell, 1932, Rodgers, 1971). It is a favorite subject of textbooks of historical geology which often illustrate and discuss the relationships displayed at the unconformity for example Dunbar and Waage, 1969, Figs. 9-8 and 9-9, Kay and Colbert, 1965, p. 174, 214).
By contrast, the structural significance of the Taconic unconformity has received little attention. The entire subject of deformation of unconformities has been neglected in comparison to its structural importance. The numerous existing studies of multiple deformation deal mainly with superimposed folding deep in the basement complex and very few of them take into account what happens at or near unconformities. Textbooks in structural geology often do not even mention the subject. The field trip area offers excellent opportunities to study the effects of folding of an unconformity and the underlying as well as overlying rocks. The plan of the field trip is to start by inspecting the formations involved in places where the structure is simple and then to proceed to outcrops at which folding of the unconformity has complicated the structures.
The present field trip is an outgrowth of class field trips I have conducted for my structural geology class. It is based on study of easily accessible outcrops that are particularly instructive by virtue of the major and minor structures they exhibit. Study of these outcrops has been carried only to the point of developing a conceptual scheme to explain the structures visible. Thus identification of formations is in some cases still tentative and I have made no attempt to record attitudes on an areal basis. Thus much work remains to be done and the field trip area should be a highly rewarding subject for one or more studies of structural details. It is difficult to find two unconformities in which the geometry of the older structures and the mechanical properties of the rocks are exactly alike at the time of the second deformation and the general principles of multiple deformation apply here to a unique array of structural details.

B2: STRUCTURAL GEOLOGY OF THE TACONIC UNCONFORMITY

Start of a long road-cut in Austin Glen Graywacke.

Erratic Boulder
Note large erratic boulder in road-cut on left side.
2013: No longer there, according to StreetView.

STOP 1. Austin Glen Graywacke.
Beds of sandstone and shale in the Austin Glen Graywacke exhibit here very regular structures indicating that only one orogeny produced major deformation in this locality. Good slaty cleavage developed in shaley layers.

Slate in road cut.

Small shale road cuts for next two miles
For next two miles there are several small road cuts in shale (possibly Snake Hill).

Gently deformed Austin Glen
Outcrops of Austin Glen Graywacke show only gentle deformation.

STOP 2. Two roadcuts in the Austin Glen Graywacke
Two roadcuts in the Austin Glen Graywacke show some of the variations in lithology in the unit. Again the structure is very simple, suggesting that the Taconic orogeny had little effect at this locality.

Gravel pits on left side of road.

Roadcut in Onondaga Limestone.

Onondaga Limestone exposures
For next mile outcrops of Onondaga in roadcuts and in back buildings.

Road cut in Esopus and Schoharie Formations.

STOP 3. Anticline
Anticline in Lower Devonian Becraft, Alsen and Port Ewen formations exposed in roadcut on both sides. The regular curvature for the formations is characteristic of flexural slip folding where there are not complications caused by the underlying rocks.

Road cut in Coeymans, Kalberg and New Scotland formations

STOP 4. The Austin Glen Graywacke
The Austin Glen Graywacke forms the bottom part of the outcrop at the north end. It is unconformably overlain by the Rondout Formation but the unconformity itself is not well exposed because of weathering of the contact. A number of faults cut through the limestones above the unconformity. Their presence lets one to expect massive graywacke underneath the unconformity.

STOP 5. Outcrop of Taconic Unconformity
One of the best outcrops of the Taconic unconformity in the Hudson Valley.
In places the unconformity is torn open into a tension gash and occupied by a quartz vein. Walking a short distance south along the outcrop one can see numerous slickensided shear fractures, blocks of shale displaced along curved or irregular shear fractures and rotated as a result so that the directions of the slaty cleavage vary in the outcrop. Note the contrast between the highly complex and irregular structure in this outcrop and the very simple and regular structures at Stops 1 and 2.

STOP 6. Sharp flexure in Schoharie Formation.
It probably lies in the continuation of a fault separating relatively large rigid blocks below the unconformity.

STOP 7. Long roadcut.
A variety of structures can be observed on the north side of the highway. A series of folds including chevron folds and isoclinal folds in a predominantly graywacke unit has moved as a single rigid block. It is in fault contact with a predominantly shaley sequence that is intensely sheared so that the original continuity of the beds is destroyed. Tension gashes can be seen cutting some graywacke beds. Shale layers in the chevron folds are greatly thickened in the hinges by flow folding. Some graywacke layers exhibit sole markings at their bottom.

Folds in Austin Glen Graywacke.

Roadcuts in Austin Glen Graywacke.

Note quartz veins in outcrop at right.

STOP 8. Intensely sheared shale and graywacke.
In places the strata have been turned virtually into a tectonic breccia with an appearance resembling a melange. Note slivers of graywacke floating in a shale matrix. The direction of the slaty cleavage is variable. Close study is needed to determine whether two intersecting directions of cleavage actually exist or whether different slices of shale have been rotated out of their original position.

B3: STRATIGRAPHY AND PALEONTOLOGY OF THE BINNEWATER SANDSTONE FROM ACCORD TO WILBUR, NEW YORK
Russell H. Waines
Department of Geological Sciences
State University of New York College at New Paltz
The Binnewater Sandstone was first recognized as a stratigraphic unit by Hartnagle (Binnewater quartzite, 1905, p. 346). It has long been recognized in outcrop within a narrow, structurally complex belt extending nine miles southwest from Wilbur (just south of Kingston) to High Falls. In addition, the Binnewater Sandstone has been recognized in boreholes just west of High Falls (Berkey, 1911, p. 132), near Accord (Port Jackson) (Johnsen and Waines, 1969, p. 30) and near Wawarsing (Bird, 1941, p. 276-278). These borings are located eight tenths, six and twelve miles southwest of High Falls respectively so that the total linear extent of the Binnewater as presently recognized is about twenty-one miles.
The Binnewater Sandstone thickens progressively from Wilbur where 4.3 feet have been measured on the east bank of Roundout Creek to about thirty feet in the Rosendale area to about forty feet at High Falls to about sixty at Accord. Bird's stratigraphic columns for Wawarsing (1941, p. 276-278) indicate 125 or 170 feet depending on the scale of the column used. According to his lithologic descriptions the thickness is more likely 85 or 105 feet. In addition, the scale in his column on page 278 seems to be in error. North and east of Wilbur the Binnewater has apparently been removed by pre-Rosendale erosion.
The lithology of the Binnewater is variable. From High Falls northeast to Wilbur it is predominantly a slightly dolomitic, fine to medium-grained quartz arenite with sparse interbeds of dolomitic shale and argillaceous dolostone. Southwest from High Falls interbeds of dolomitic shale and argillaceous dolostone tend to increase at the expense of the sand content. Non-sand content increases southwest from High Falls to Accord to Wawarsing from about five to fifty to apparently seventy per cent.
The sandstones of the Binnewater are generally dark grey to light grey to white, weathering orange to buff to grey to white. Increase in dolomite content is attended by an increasingly orange to rusty appearance when weathered. Shales and dolostones within the Binnewater may be dark grey to light grey-green. Again, increasing dolomite content is accompanied by an increasingly darker rusty color. Distinct red coloration more typical of the High Falls Shale may occur in sandstones, shales or dolostones and varies from traces at High Falls to about 15 per cent in drill core at Accord to perhaps as much as 30 per cent at Wawarsing.

B3: STRATIGRAPHY AND PALEONTOLOGY OF THE BINNEWATER SANDSTONE FROM ACCORD TO WILBUR, NEW YORK

Bridge over Wallkill River.

STOP 1. Complete exposure of Binnewater Sandstone
Complete exposure of Binnewater Sandstone can be seen at this stop; including upper contact with Rosendale Dolostone, upper massive sandstone unit, poorly developed underlying shale unit, main cross-laminated sandstone unit, lower shale unit, bottom dolostone breccia unit and possible lower contact with the High Falls Shale. Cross-laminations, ripple marks and desiccation cracks can be observed in the middle unit. Casts of salt hoppers have been found in the upper part of the middle unit and will be displayed in the Geology Department at Vassar College at the conclusion of this trip. Studies of cross-laminations by Ringler (1970, 1971) and of sand grain orientations by Fields (1975a, 1975b) indicate a preponderant net shift of sediment to the northwest (N36°W) with a statistical allignment of long axes of sand grains (N80°E-S80°W). This may indicate that the bulk of the sand grains progressed northwestward as "rollers" rather than as "sliders". A tidal flat environment is proposed for most of this section.
Caution -This road cut has become increasingly unstable over the years. Watch out for falling rocks and blocks!

Bridge over Rondout Creek.

Lefever Falls below to the right
Lefever Falls below to the right has been somewhat modified by the U.S. Army Corps of Engineers.

Park on loading platform
At bottom of hill after passing through a descending left-hand curve park on loading platform on the right. This platform once served barges berthed in a turning basin of the Delaware and Hudson Canal. The canal was last used around the turn of the Century.

STOP 2. Lefever Falls Mine
Caution - Please do not fall into the mine as accidents will impede the progress of this field trip and we are on a tight schedule! Do not crowd one another near the edge of the mine!
A nearly complete section of Binnewater Sandstone can be seen at this stop in the southwest wall of the mine entrance. It is not as well exposed as that in STOP 1 due to cover by mosses and lichens. The upper massive sandstone has been removed by pre-Rosendale erosion. The shale beneath is not exposed but can be seen several hundred feet to the south on the dip slope of the top surface of the main sandstone unit. The contact between the Shale and the overlying Rosendale Dolostone can be observed in the vicinity only with difficulty. The lower shale unit and the bottom argillaceous dolostone unit can be observed on both the north and south walls of the mine entrance. Pass through the archway in the wall on the left (south) and proceed with care past the steeply dipping mine opening on the right. Your first slip may be your last. Continue south for several hundred feet with the dip slope of the main sandstone unit on your left. Where possible, examine the slope for signs of silicified, hemispherical stromatoporoid coenostea in growth position. Should you find one please do not collect it as our studies of this location are not completed. Continue south until the upper shale unit is reached and can be examined. The significance of this locality is discussed in the text.

STOP 3: A complete section of Binnewater Sandstone
Sandstone can be seen with all units as at STOP 1 but the upper dolomitic shale unit is much more clearly defined. The relief on the top of the upper massive sandstone unit can be seen on the dip slope of the floor of the mine where the overlying Rosendale Dolostone has been removed. The Binnewater-High Falls contact probably lies within or at the base of the lower argillaceous dolostone unit. Studies of cross-laminations and ripple marks by Christianson (1969) indicate a marked net shift of sand toward the southwest (S75°W). Some years ago Susan Mocco, a student in the Dept. of Geological Sciences at S.U.N.Y. New Paltz, studied this section extensively to determine if there was indication of periodicity in the lithological variation within the main sandstone unit. The variation appears to be more random than periodic. Note the silicified stromatoporoid coenosteum in the upper massive unit, and flat shale pebbles in the bottom of the main sandstone unit.
Caution - As at STOP 2. please avoid falling into the mines as it will unnecessarily delay the trip!

STOP 4. Binnewater sandstone / High Falls shale
Binnewater sandstone unit in contact with High Falls Shale
Caution -The roadway is narrow and local drivers often speed along this stretch.
At this location the main sandstone unit is all that remains of the Binnewater at this latitude and it is in distinct contact with the High Falls Shale. The lower shale unit and the bottom dolostone unit are missing, probably indicating an onlap relation with the High Falls in an apparent northeast direction. The High Falls at this location is an uncharacteristic, poorly sorted, argillaceous, quartzose, quartz pebble-bearing material which was mistaken for a basal unit of the Binnewater sandstone by Waines and Sander (1968. p. 18).

Pass under Nytrallte conveyor.

STOP 5. Main sandstone unit of Binnewater
At this location the Binnewater Sandstone consists solely of the main sandstone unit which is completely exposed at the north end of the outcrop. The unit consists of an upper dark, somewhat silicified portion and a lower lighter colored portion. This subdivision occurs only locally. Cross-lamination is primarily confined to a very narrow zone. Dolomitic content in this section is uncharacteristically high. The Binnewater-Rosendale Dolostone contact is delineated by a discontinuous line of bleeding pyrite and can be closely observed at the north end of the outcrop. The Binnewater-Ordovician contact can best be seen near the base of the outcrop several tends of feet south of the main exposure of Binnewater. The contact is in angular unconformity with Ordovician shales, siltstones and greywackes. Quartz pebbles occur within the base of the Binnewater up to several inches above the contact. In several large blocks of Binnewater Sandstone which have fallen forward from the outcrop a cross-laminated, ripple-marked, mud-cracked bedding plane can be observed along with the Binnewater-Rosendale contact. Preliminary estimates of net sand transport from cross laminations indicate a general net shift to the south.

STOP 6: Rondout Creek Falls
Walk north to edge of Rondout Creek and observe falls from platform. Do not crowd! Upper contact of Binnewater Sandstone with Rosendale Dolostone occurs near base of falls and can be observed only with difficulty if at all. A complete exposure on the far side of the river is not accessible on this trip. Continue downhill (east) on paved road and observe exposure of Binnewater on right (south). This sequence lies somewhere in the middle and lower part of the Binnewater. Generally the Binnewater is not quite the same as in the Rosendale area. The sands especially in the lower part become somewhat vugular and tend to be more dolomitic.
Occasional traces of red coloration begin to appear. The lowermost five feet or so are somewhat transitional to more typical High Falls lithology. The lower part of the section is in some ways more akin to that in the Accord drill core which will be displayed at Vassar at the conclusion of this trip.

STOP 7. Rosendale Limestone
Here the Rosendale Limestone contains a highly arenaceous unit at the base which disconformably overlies a laminated, soft weathering, argillaceous dolomite with the fissility of shale. This has been referred to as the Accord Shale by Fisher (1959). Drill cuttings of the top six feet of this unit obtained in a nearby quarry were examined for insoluble residues through six inch intervals by Ruth Ellen Nielson, a student at S.U.N.Y. New Paltz several years ago. All residues proved less than half the samples by weight; generally between thirty and forty-five per cent. Harry Dembicki, another student, determined a general fifty-fifty ratio in the Ca/Mg ratios in the dissolved portions of the samples suggesting dolostone. According to drill core taken in a nearby boring, this argillaceous dolostone unit is about 14 feet thick. The disconformable contact with the overlying Rosendale Limestone can also be seen in the same core. There is a possibility that ostracods may be found in this outcrop. One was encountered in the drill core in about this interval. Possible relation of this dolostone to the Binnewater Sandstone at High Falls is indicated in figure 2.

On left is quarry
On left is quarry mainly excavated in Rosendale Limestone. Road skirts northwest side of quarry. Drill core mentioned at STOP 7 was taken on far side of quarry.

B4: STRATIGRAPHY AND STRUCTURE OF SILURIAN AND DEVONIAN ROCKS IN THE VICINITY OF KINGSTON, N.Y.
Kenneth Pedersen
Michael Sichko, Jr.
Manfred P. Wolff
INTRODUCTION
On this trip the lower contact of the Rondout formation will be observed at two locations. In the southernmost exposure at Tillson Hill the Rondout lower contact is sharp to gradational with the Binnewater sandstone. The significance of this contact is that it is in paraconformity or conformable with the earlier Silurian rocks.
At stops two and three to the north of Kingston (Fig. 1) the lower contact of the Rondout formation lies in angular unconformity to the Ordovician Normanskill formation. At these two northern stops the Shawangunk conglomerate, High Falls
shale and Binnewater sandstone are all missing. There are three possible hypotheses which may explain this :
a. The northern area was being eroded while the southern area was submerged for deposition (a Silurian shoreline).
b. The northern area was undergoing deposition and later erosion. Thus, eroding the unconsolidated earlier Silurian sediments (a regressive sea).
c. In the later Devonian time, the entire area was thrust faulted and the angular unconformity is a thrust fault plane.
The authors favor explanation "a" since the missing formations are all thinning in a northeasterly direction although there is some evidence in support of each hypothesis
In the later Silurian the upper part of the Rondout formation was gradationally deposited with the Thacher limestone of Early Devonian. The Silurian-Devonian time division has therefore been placed within the upper Rondout formation (Rickard, 75). The Early Devonian was characterized by rather low energy environments in which a general carbonate and calcareous mud sequence was deposited.
The lower Devonian carbonates are exclusively marine, although the energy levels vary indicating fluctuations in sea level throughout the area. The lowermost Thacher limestone is variable from low to high energy levels perhaps tidal to subtidal while the Thacher is biostromal near the top.
From the overlying Ravena limestone through the Kalkberg limestone and New Scotland formation the energy levels fell off and the sea level was rising until the depth exceeded 200 feet at local wave base level. This sequence was followed by a recession of the sea during the deposition of the Becraft limestones. The environments deepened again during the deposition of Alsen limestone and the Port Ewen formation.
Fluctuations occurred perhaps during the deposition of the Glenerie formation and stabilized in a deep water environment during Esopus and Schoharie times (Waines, 67).
The Middle Devonian Period is initiated with the deposition of the cherty Onondaga Limestone which has been subdivided into various units (Oliver, 1956, 1962). Only the Edgecliff and Moorehouse members occur in this region. This culminates the lower Paleozoic periods of carbonate deposition; the remainder of the Paleozoic is now characterized by the various clastics derived from the uplifted New England provinces deformed during the Acadian orogeny.
The first major pulse of sediments (Hamilton Group) form a vertical and lateral progradation of marine, coastal, and alluvial deltaic environments that continue to fill the various embayments near the edge of the basin and spread westward across the state - the initial development of the classic Catskill delta or deltaic complex (Barrell, 1913, Chadwick, 1933, Wolff, 1965, Friedman and Johnson, 1966).
This trip will examine some of these sediment phases or "facies" as represented by the Marcellus Formation (Table 1). Each of these units can be traced northward by physical correlation because of the similarity between regional structure (the Hoogeberg escarpment) and depositional strike, and then westward by thickening rates (Rickard, 1964) and paleontological control (Cooper, 1933). The vertical section of rock units and inferred depositional environments seen here are quite similar to those seen southward toward Pennsylvania (Mazzullo, 1973) and northward toward Albany (Wolff, 1969).
The Onondaga Limestone is conformably overlain by the fissile, black, Bakoven Shale which transitionally grades into the Stony Hollow Siltstone. Both of these units are slightly calcareous. They are overlain by a thick sequence of interbedded dark gray shales, siltstones, and massive fine-grained sandstones (Mt. Marion Fm.), and these transitionally grade into the cross-bedded, relatively unfossiliferous, sandstones of the Ashokan Formation. This unit, of variable thickness, is also transitionally overlain by the sandstones and shales of the Plattekill Formation. The presence of red shales and mudstones in place of only olive-green knobby mudstones adjacent to and in conjunction with the cross-bedded sandstones, is used as the facies boundary between these units.
The entire vertical section represents the single initial deltaic progradational sequence followed by a series of at least four other major deltaic sequences (Wolff, 1965, 1969) within the Devonian "Catskill deltaic complex." Road stops (5A-B) will begin at the top of the section (Table 1) in the Plattekill Formation and end at the Bakoven Shale. Previous trips examining the stratigraphy of this area include: Dunn and Rickard (1961), and Wolff (1969).

B4: STRATIGRAPHY AND STRUCTURE OF SILURIAN AND DEVONIAN ROCKS IN THE VICINITY OF KINGSTON, N.Y.

STOP 1. Silurian System - Tillson Hill, N.Y.
This stop shows an exposure of the formations of Silurian age which are exposed in the Hudson Valley. The Shawangunk conglomerate, the High Falls shale and the Binnewater sandstone are all found below the Rondout formation. The contact between the Binnewater sandstone and the Rondout formation is conformable at this locality. Farther North, however, the Rondout is found in angular unconformity to the underlying Normanskill formation of Ordovician Age. Proceed north on route 32 toward Kingston, N.Y.

STOP 2. Subterranean Ord/Sil unconformity.
Subterranean exposure of the Ordovician-Silurian angular unconformity.
The steeply tilted Normanskill formation is exposed in angular unconformity with the Rondout formation. At this location the only remnants of the Rosendale and Whiteport members are the columns which support the roof in the mines (Fig. 3).

STOP 3. Subaerial exposure of unconformity
Again the Normanskill-Rondout angular unconformity. At this locality, major structural deformation due to the Taconic Orogeny are easily observed.

STOP 4. Thrust faulting
Thrust faulting within the Thacher member of the Manlius limestone:
The Thacher limestone shows major structural deformation from the Acadian Orogeny in the form of thrust faulting. The carbonaceous interbedded shales have been metamorphosed into phyllites and phyllites schists.

New Paltz Ashokan campus. Lunch Stop

STOP 5A: Plattekill Formation (Catskill Facies)
Stream channel environment.
Exposure consists of 14 feet (4.3 m.) of flat bedded and planar cross-bedded sandstones. These occur in a series of overlapping and truncated wedges averaging 1-3 feet (0.3-1 m.) in thickness (Figure 5). The individual dark subgraywackes are 1/2 to 2 inches (1-3 cm.) thick and form accretionary slopes of 2-5°, While the regional direction of flow is S80°W, the individual sets of crossbeds trend northeast-southwest. Rather than a major upward-fining alluvial channel, this section is interpreted as an area of shallow distributary or braided stream channels laterally filled through point bar accretion and vertically filled by channel aggradation.

STOP 5B: Plattekill Formation (Catskill Facies)
Floodplain environment.
Base of outcrop consists of 17 feet (5.2 m.) of knobby red-green mottled mudstone grading upward into 4-6 feet (1.3-2 m) of olive green mudstone. Section is disconformably overlain by a sequence of medium-gray, shallow-dipping planar cross-bedded sandstones. The regional paleoslope across the megarippled erosional surface trends S70°5. The zone of recent differential erosion about 8 feet (2.5 m) above the base represents a section of westward lateral compression producing minor folding, slickensides, and thrusting within the red mudstones - a minor decollement (Figure 6.) This section is about 200 feet (61.5 m.) above the base of the Plattekill Formation.

STOP 6: Skaneateles-Marcellus Formations
(includes the local Ashokan and upper Mt. Marion Formations)
Contains features characteristic of the Chemung-Hamilton facies (intertidal environment). Use parking lot of Micrometries, Inc. on the south side of the road.
A. Southside of Rt. 28 roadcut - Mottville and Ashokan Sandstones. Major feature is the 8 foot (2.6 m) laminated and cross-laminated, moderately sorted, planar crossbedded sandstones. These occur on a series of en-echelon "sand bars" here, over 130 feet (40 m.) wide and interbedded with dark shales and massive, fine-grained, bioturbated sandstones. These bars strike N70°W and have steep "foreshore" slopes (20°) trending northeast with more gentle (10-15°) "backshore" dips. Overlying the sandstones is a 5 foot (1.8 m.) succession of dark shales and fine-grained laminated sandstones with abundant plant fragments. This part of the section has been traced to Schoharie Valley (Mottville Sandstone) and is interpreted as a series of river mouth bars, intertidal or shallow subtidal sandbars, and sandflats (Wolff, 1969). These marginal sandstones are steeply truncated by a 40 foot (12.6 m.) section of thick, large-scale trough and planar cross-bedded sandstones with irregular lenses of olive mudstone (Figure 7). Individual beds are 2-4 inches (4-7 cm.) thick and dip at angles of 2-10° to the northwest. Worm burrows, shale chips, and plant fragments are common. This section represents the first major intertidal channel cutting across the sequence (Ashokan sandstone). The paucity of marine fossils may reflect the alien ecologic conditions that would be associated with the rapid lateral and vertical erosion and sedimentation in this environment. However, small crustaceans Estheria (a brachiopod) and Beryrichis (an ostracod) have been collected in several areas at this interval (Goldring, 1943, p. 268) supporting a brackish-water interpretation.
B. North side of Rt. 28 -upper Mt. Marion Formation. Suggested to be equivalent to Pecksport member of Marcellus Formation (Copper (in Goldring) 1943, p. 260, and Wolff, 1967, 1969). Outcrop consists of 9 feet (2.8 m.) of brown-black interbedded shales and siltstones capped by a 3 foot (1 m.) bed of dark, small scale, planar cross-bedded sandstone (equivalent to base of section on south side of road). Many of the shales exhibit an "oily" iridescent purple sheen. Structures include wave ripples, laminations, cross-laminations, lenticular bedding, flaser bedding, worm burrows, and tidal bedding -all features that can be associated with lagoons and tidal flats (Reineck, 1963, Klein, 1970). Fossils include Schizophoria, Pterinopecten, Paraspirifer, and Tropidoleptus, and are representative though not diagnostic for the uppermost Marcellus (Pecksport member). This area is interpreted as a region of wide sand flats containing barrier base and beaches, lagoons or tidal channels, and marshes or swamps that formed between deltaic layer during a period of general submergence. (Figure 8). After submergence (Pecksport interval -A) there is an interval of transgression, reworking, and nearshore deposition (Mottville interval -B), before the next major pulse of deltaic sedimentation (Ashokan interval -C)

STOP 7. Marcellus Formation
(Portage Marcellus Facies)
Stony Hollow and Bakoven members (distal slope and basin environment)
Base of section consists of 22 feet (6.6 m.) of thinly laminated black calcareous shales, commonly drag folded and faulted (underthrusts). The next 8 feet (2.3 m.) also contain black calcareous concretions (frequently slickensided), and compression fractures with quartz veins. The Bakoven is about 100 feet (30 m.) thick, but only the upper portion is exposed here. This unit grades into 8 feet (2.3 m.) of dark gray massive calcareous siltstones. The near vertical joints, trending N60°E are quite characteristic. Upon weathering the buff-colored surfaces exhibit the laminations or cross-laminations commonly associated with this unit. These may represent deposition by waning turbidity, or other marine currents. The siltstones contain some detrital carbonate and a few fossils, and become more massive through this 35 foot (11 m.) section. It is equivalent to the Cherry Valley (Agoniatite) Limestone in central New York and was first described by Cooper (in Goldring), 1943.

STOP 8: Marcellus Formation Portage Facies
Locally the lower Mt. Marion Formation or the sandy equivalent of the Chittenango member of east-central New York.
Road cut consists of 120 feet (37 m.) of dark gray arenaceous shale with some anomalous interbedded fine-grained sandstones through the lower 20 feet (6.2 m.) of the section. The overlying shales contain light gray concretions and include 5 "coquinite" fossil horizons. Of significance is the Meristella -coral zone in the central zone (now covered by the weathered shale) and horizons of brachiopods and pelecypods. Cooper (in Goldring) 1943, traced this horizon from the Berne Quadrangle (S.W. of Albany) into this area. The interval between the Stony Hollow member and the Otsego Shale was designated as the "Berne member" (Cooper, op. cit., p. 249) but it was restricted because of the few known locations. The extension of this member to the Kingston area enables it to be also correlated as the sandy equivalent of the Chittenango Shale (Cooper, op. cit.), and establishes the contact between this shale and the Otsego Shale in this region (Wolff, 1967, 1969). The pull apart and transposition structures at the base of this section (Figure 9) are described in the structure section of this article.

STOP 9. Gentle folding in the lower Devonian Rocks
Here the gentle anticlines and synclines expose the lower Devonian section almost in its entirety. We are proceeding downward in the column so the rocks encountered are in the following sequence: Schoharie, Esopus, Glenerie, Port Ewen, Alsen, Becraft, New Scotland, Kalkberg, Ravena and Thacher (Waines, 1967).

B5: PLEISTOCENE HISTORY OF THE MILLBROOK, NEW YORK REGION
David J. Murray
LaGrange Junior High School
Pleasant Valley, N. Y.
Location, Physiography, Relief and Drainage
The Millbrook, New York quadrangle is centrally located in Dutchess County, New York, mid-way between the Hudson River and the State of Connecticut (to the east) and New York City and Albany (to the north). The topography of the southern half of the quadrangle is generally hilly with areas of low relief be tween the hills. These areas appear to be lake plains of ice-marginal lakes formed during the retreat of the continental ice sheet from the Mid-Hudson Valley. Subsequent erosion of the lacustrine deposits has formed flood plains and terraces. The lowest elevation, about three hundred feet above sea level, occurs on the western border of the map area in the flood plain of the east branch of Wappingers Creek. A series of progressively higher rock ridges trending northeast-southwest traverse the quadrangle. The highest elevation, Tower Hill, rises to 1323 feet. The valleys between these ridges are probably pre-glacial in origin but at present are partially filled with glacial deposits. The larger valleys have terraces along the sides.
The area is drained by tributaries of three major creeks. Tributaries of Wappingers Creek on the west and Fishkill Creek on the south, flow into the parent streams and then into the Hudson River. The extreme eastern part of the area is drained by unnamed tributaries of the Ten Mile River, which flows into the Housatonic River in Connecticut. These tributaries originate in elevated bogs and small kettle ponds and lakes.

B5: PLEISTOCENE HISTORY OF THE MILLBROOK, NEW YORK REGION

Cross Wappinger's Creek.
This creek provides drainage from field trip area.

Pass Dutchess County Farm and Home Center.
This site is on the east side of former Glacial Lake Washington.

Pass Bennett College

STOP 1. Town of Washington Disposal Area.
Sanitary Landfill. This is the highest level of the field trip area. Look for massive kettle holes and distorted bedding, due to slumping as buried ice blocks melted. Top elevation 900 feet.

STOP 2. Deltaic deposit
Deltaic deposit consisting of foreset and topset beds dipping west indicating source of sediments from east into Glacial Lake Mabbettsville.

STOP 3. Observe lake plain and lake terrace
Pull into Dutchess Day School Driveway on right. Observe lake plain and lake terrace indicating Glacial Lake Mabbettsville.

Kame and kettle topography
Note kame and kettle topography on right in field next to swimming pool.

STOP 4. Large gravel pit.
The sand and gravel from this pit is used "as is" as a high grade bank run gravel. It is quite well sorted and fairly free of silt and clay sized particles. Foreset and topset beds visible in this massive deltaic deposit in Glacial Lake Washington.
2013: Good Google Earth image from 1994 shows excavation.

Lunch Stop. Cary Arboretum
The Cary Arboretum of the New York Botanical Garden is a 2000 acre tract of land devoted to botanical research, applied environmental science, and education about plants. It was established in 1971 with a grant of land and funds from the Mary Flagler Cary Charitable Trust on an estate owned by the late Mrs. Cary.

STOP 5. Level ground underlaid with deep gravel
Level ground underlaid with deep gravel; bedding almost horizontal. Look for fairly well sorted gravels and stagnant ice features.

STOP 6. Level field is a delta surface
Level field is a delta surface at 440 feet elevation. Soil on left side of road is dramatically different from soil on right side of road.

Bear right across Glacial Lake Washington plain.

STOP 7. Bridge across Wappinger's Creek.
Inferred history of Glacial Lake Washington will be discussed.

STOP 8. Gravel pit
Gravel pit is an exposure of poorly sorted outwash overlaid with ground moraine on western margin of Glacial Lake Washington.

Deltaic Deposit
On right side of Route 82 at this point a deltaic deposit was removed for road building material. Bones thought to be those of Indians were found here in 1973 but have not yet been authenticated.

STOP 9. Large gravel pit
This large gravel pit operated by the Route 82 Sand and Gravel Company has a variety of features that will be discussed here.

B6: STRATIGRAPHIC AND STRUCTURAL GEOLOGY IN WESTERN DUTCHESS COUNTY, NEW YORK
by
Donald W. Fisher State Paleontologist, Geological Survey,
New York State Museum and Science Service, Albany, New York 12234*
and
A. Scott Warthin Jr.
Professor Emeritus, Geology, Vassar College
Poughkeepsie, New York 12601
*Published by permission of the Director, New York State Science Service. Journal Series No. 217.
PROLOG
Sedimentary rocks with deceptively similar but subtly different physical characteristics and yielding rare and hard-to -identify fossils demand exceedingly careful scrutiny. When, however, a further measure of obscurity arises because such rocks are overprinted by poly-deformational complex folds, faults, cleavage, and metamorphism, the demands made upon the investigating geologists are, indeed, taxing. This is the situation confronting those who attempt to unravel the geological maze of Dutchess County and eastern New York.
On this trip, our intention is to expose you to some of the knotty problems that beset us and permit you to examine some of the typical rock units and typical structures of the region. Owing to time limitations, we shall confine our visitations to western Dutchess County from Poughkeepsie northward -- and not all the rock units nor all types of structures will be examined. If we make you aware of the fascination and frustration of Taconic geology, then we have succeeded in our mission.
ACKNOWLEDGEMENTS
John B. Skiba, Senior Cartographer with the New York State Geological Survey, skillfully prepared the charts and maps which accompany this article and make for better understanding of the perplexing geologic relationships. The pictures taken from the U-2 aircraft and the ERTS satellite image were furnished by Yngvar W. Isachsen of the New York State Geological Survey.

B6: STRATIGRAPHIC AND STRUCTURAL GEOLOGY IN WESTERN DUTCHESS COUNTY, NEW YORK

Middle Ordovician Snake Hill Shale on left.
Proceeding in lower Ordovician-Cambrian carbonate valley. Megabreccia (?) of carbonate blocks deposited on Snake Hill mud.

Road cut in Rochdale Dolostone.

Village of Pleasant Valley, crossing Wappinger Creek.

Lower Cambrian Nassau pelites
Have entered the Van Buren gravity slide.

Lower Ordovician Stuyvesant Falls green shale
Lower Ordovician Stuyvesant Falls green shale, and thin quartzites on NW(left).

STOP 1. Camb-Lower Ord Germantown Fm
Intersection of Drake-Rossway Rds. &T.S.P. Exposures of Cambrian-Lower Ordovician Germantown Formation along both lanes of T.S.P., north of intersection. We shall examine only the western cut on the southbound lane. Here, almost vertical dipping platy, silty shale with very thin-bedded limestones and carbonate-clast carbonates are superbly exposed. Tight drag folding indicates that we are on the eastern limb of a larger synclinorium. Note the quartzose limestone beds. These and the carbonate-clast conglomerates have large and well-rounded frosted quartz grains; the clasts consist of fine-textured limestones and differing types of dolostones and black phosphate pebbles. These conglomerates are thought to be lag-turbidites on an ancient continental slope.

Lower Cambrian Nassau shales and argillites.

Valley floored with outwash gravels.

Kame terrace on E side of valley.

Everett Schist in hill on left.
Lower Cambrian or Late Proterozoic Everett Schist in hill on left. Everett is thrust-faulted, westwardly, onto Middle Ordovician Snake Hill (= Walloomsac) Shale.

STOP 2. Intersection of Todd Hill Rd. and T.S.P.
Here we have a geological enigma -- an exposure of Proterozoic gneiss in an area far removed from larger masses of Proterozoic gneiss. This orange feldspar-rich granite gneiss does not have a normal shelf stratigraphy (Poughquag Quartzite, Wappinger carbonates) associated with it as does the Cronomer Hill section at Newburgh or the Stissing Mt. section near Pine Plains. Todd Hill and a smaller hill to the SW are flanked on the east by Everett Schist and Mount Merino(?) Shale. respectively. These two gneiss hills are bounded on the W by a major NE-trending fault. The field relations deny the views that these gneiss hills were islands around which Cambrian and Ordovician sediments accumulated or that the gneisses were up-punched due to doming or normal block faulting (horst). The gneiss owes it position as a result of far-travelled movement--either as a sliver along a low thrust fault or as an erosional outlier of a once larger overthrust mass of gneiss, such as the Hudson Highlands. We prefer the sliver supposition.
2013: Crossing the Taconic State Parkway is no longer considered a good idea, so we will go back, and around, to get to the other side.

STOP 3. Normanskill Group
Noxon Rd. E of Sprout Creek (D.C. 21) rock cut. Here, we have the Mt. Merino Shale on the west and the Indian River Shale on the east -- the middle and lower divisions of the Normanskill Group, respectively. The Mt. Merino is a gray to black shale or mudstone locally with gray to black chert; the Indian River is a pale green to red to maroon shale or mudstone with light green to red chert; within the Indian River here is an unfossiliferous dove-tan-gray, fine-textured limestone. Three and possibly four episodes of folding are displayed here. One set has horizontal axial planes, another has westward dipping axial planes with N-plunging folds, and a third are small drag folds which appear to be refolded. In addition, the penetrative cleavage is folded. The interpretation is that this outcrop exposes a portion of a lower limb of a westwardly overturned fold (nappe). Small discrete bodies of graywacke, more convex upward and to the east, are probably turbidites; they too, are upside down. No fossils have been found at this exposure but elsewhere, where less deformed, the Indian River and Mt. Merino yield graptolites characteristic of the Nemagraptus gracilis zone of the Early Medial Ordovician.

Spackenkill Rd. (D.C. 76). Slow, but no full stop.
On S (left) side of Spackenkill Rd. is a block of Wappinger (Briarcliff) carbonate in the Snake Hill Shale. This is regarded to be part of an extensive NE-trending megabreccia extending from the Cronomer Hill area at Newburgh, generally following Wappinger Creek and reaching Stissing Mountain near Pine Plains. Although the precise sequence of deformational events is uncertain, this megabreccia is believed to be an early melange deposit in the Snake Hill mud, created by the ripping-up of underlying shelf carbonates as the pelitic Van Buren gravity slide moved westward. This exposure is but one of many carbonate blocks illustrating various attitudes and differing Wappinger units.

STOP 4. West side of Cedar Valley Rd..
(NO ROCK BREAKING OR SAMPLING, PLEASE.)
Here, we have opportunity to see the significant Middle-Lower Ordovician contact, -- a profound erosional unconformity on a regional scale. At this exposure, the Middle Ordovician (Mohawkian) Balmville Limestone rests on the Lower Ordovician (Canadian) Rochdale Limestone. In some parts of the Hudson Valley, the Balmville rests on older rocks -- as old as Medial Proterozoic gneisses.
The Balmville consists of medium-dark gray, coarse-fine textured limestone, fossil fragmental, and, locally, with a pebble conglomerate composed of clasts of finer textured, light gray weathering limestone of buff-weathering dolostone. Some "clasts" are colonies of the alga Solenopora. The Balmville is relatively fossiliferous but whole specimens are difficult to obtain. Brachiopods, crinoids, and bryozoans are the principal taxa; algae, conodonts, gastropods, ostracodes, and trilobites are secondary taxa. The subjacent Rochdale Formation is fine-textured, bluish-gray to black limestone with interbedded paler bluish-gray, buff weathering dolostones. In some beds. the proportion of calcite to dolomite varies considerably; this produces a fretwork appearance to the weathered surface. The Rochdale is Medial Canadian (Demingian) age as evidenced by the diagnostic discoidal gastropod, Leaanospira, the trilo Hystricurus conicus, and the cephalopods Bassleroceras, Dwightoceras, and Vassaroceras. Stromatolites are also occasionally seen. The Rochdale seems to have been deposited in a low-energy, distal intertidal environment whereas the Balmville is a product of extremely high-energy conditions on an ancient beach.
The dip varies from 55°E at the northern end of the exposure to near vertically at the southern end. The observed rocks are on the eastern edge of an elongated carbonate block with Middle Ordovician Snake Hill Shale occupying the lowland to the east and the adjacent lowland to the west of the NE-trending carbonate ridge.

STOP 5. East side of Cedar Ave. (D.C. 74)
This long exposure is in the Briarcliff Dolostone division of the Wappinger Group. Note the variation in textures and colors in the dolostones. Small faults with only a few centimeters displacement and microbreccias are common. A more prominent normal fault across from the parking area trends N70°E and dips almost 90°. A short distance to the east, the Briarcliff abruptly ends in a cliff; Snake Hill Shale occupies the bounding lowland. This is the eastern extremity of the relatively large block of carbonate that is exposed in the large Clinton Point Quarry on the Hudson River. Here, earthquakes have been documented from 1937 to the present. It is speculative whether this Cedar Ave.-Clinton Point block is (1) an exceedingly large block in a megabreccia, (2) an up-punched block bounded by normal faults, (3) the leading edge of a thrust block, or (4) a megabreccia block trimmed by subsequent block faulting. Because of its proximity to known, but smaller, megabreccia blocks, we favor views (1) or (4).

Note gentle dips in Briarcliff Dolostone in every exposure.

Briarcliff Dolostone
Note outcrop of Briarcliff Dolostone just north of Robert Hall Store. Dips are abnormally steep and may record bevelled isoclinal folds or indicate proximity to a fault. This is the western margin of the Cedar Ave.-Clinton Point carbonate block.

STOP 6. KAAL PARK (LUNCH)
NO HAMMERING, THIS IS A CITY PARK.
This is an exquisite exposure of a tectono-sedimentary unit known as chaos, melange, olistostrome, or wildflysch. Fisher (1976, in press) has named this unit the Poughkeepsie Melange. It consists of various sized, angular to rounded clasts of rock (with varying attitudes) in an unbedded or poorly bedded argillaceous matrix. Here, the blocks are almost exclusively Austin Glen Graywacke; elsewhere, there are varying amounts of quartzite, sandstone, shale, and carbonate. This type of sedimentary-tectonic unit is believed to result when westwardly moving rock masses broke up at their leading edge, spalled off, and tumbled downslope into a deepening basin which was receiving mud. Evidences of soft-sediment deformation are widespread. This deposit accumulated during the Vermontian Phase of the Taconic Orogeny (mid-Mohawkian time) when the Livingston and Van Buren Gravity Slides were emplaced into the Magog (Snake Hill-Martinsburg) Trough. Rocks of the Livingston Slide are superbly exposed at the western end of the Mid-Hudson Bridge.

Numerous exposures of Poughkeepsie Melange.

Culinary Institute of America on W (left).

STOP 7. Exposures on both sides of St. Andrews Rd.
Here, the uppermost member of the Middle Ordovician Austin Glen Graywacke is deformed into broad, low amplitude folds. The somewhat cyclical shale-graywacke succession is cleaved and the cleavage is slightly bent, denoting that here we are at the western limit of a folding episode which deformed the earlier regional fracture cleavage. This stop, however, is more instructive for the wealth of sedimentary features that are to be observed: load casts, cross-lamination, cross-bedding, graded bedding, intra-bed clasts, climbing ripple marks, etc. Note also, the micro-folding of the thinnest seams. The abrupt change from arenite sedimentation (graywacke) to pelite sedimentation (argillite, shale) is striking. Many of the graywackes, especially the thicker ones, are turbidites as evidenced by the variety of load casts and trapped shale or pelite clasts.
The Austin Glen Formation is thought to have been deposited on an ancient continental slope where the sediments on the sea floor were unstable. This type of substratum was inhospitable to benthonic animals. A few pelagic forms (graptolites, radiolarians) have been recorded from the Austin Glen elsewhere in Dutchess County. The lower member of the Austin Glen belongs to the Nemagraptus gracilis zone and the upper member belongs to the Diptograptus multidene zone. Because of the absence of a shelly, benthonic fauna from all divisions of the Normanskill Group, its correlation with the shelf carbonates remains equivocal. Outcrop is in the Livingston Gravity Slide.

Austin Glen Graywacke
Exposures of very massive Austin Glen Graywacke in Livingston Gravity Slide. Continues for next 0.9 miles.

Outcrops of melange near intersection.

Germantown conglomerates, limestone, and shale
Germantown conglomerates, limestone, and shale on N (left) side. Have just entered Van Buren Gravity Slide.

Entering Gallatin Thrust Slice
Elizaville argillite and quartzite in numerous exposures on both sides.

STOP 8. Elizaville Argillite and Quartzite
Early Cambrian or Late Proterozoic Elizaville Argillite and Quartzite on Slate Quarry Rd.
The Elizaville consists of hard, compact greenish-gray slate and argillite (weathering tan to orange) and interbedded greenish-gray quartzite. Elsewhere, some of the quartzites attain 10 meters thickness. Here, the thinner quartzites are traversed by cross-fractures filled with milky quartz and iron carbonate (siderite). NO HAMMERING OR COLLECTING SIDERITE!!! On the west end of the exposure, the strata form a low fold with cleavage dipping 50-60° E. Further east, the bedding and cleavage are parallel (dipping 60° E). Where this coincidence exists, the chances for good quality commercial slate are better; abandoned slate quarries may be found on both N and S sides of the road in the woods. In general, in the Gallatin Slice, cleavage is predominant over bedding. And, cleavage is virtually undeformed.
No fossils have been discovered in the Elizaville Formation. It is presumed to be equivalent to part of the Nassau Formation of the Van Buren Slide.

Mt. Merino black shale on N (left) side.
Exiting from Gallatin Thrust Slice into Livingston Gravity Slide.

STOP 9. MILAN WINDOW: WAPPINGER carbonate
MILAN WINDOW: WAPPINGER (HALCYON LAKE?) carbonate on N side of D.C. 19 near intersection with D.C. 18.
This is a NNE-trending valley floored by Wappinger carbonates, Balmville Limestone, and Snake Hill Shale. Rimming this sequence of shelf rocks are slope and basin Normanskill graywackes and pelites of the allochthonous Livingston Slide. The window of parautochthonous shelf rocks was produced by differential erosion of part of the covering Livingston Slide and additional covering Gallatin slice; the Van Buren Slide was presumably eroded prior to the emplacement of the Gallatin Slice. Subsequent normal faulting may have accelerated erosion and the creation of the Milan Window. This stacking of gravity slides and thrust slices is seen to no better advantage than in this region of the Rock City Quadrangle. Mapping of the divisions of the Wappinger Group has disclosed here, and in other lengthy carbonate terranes, the existence of a NW-SE trending fault set (strike-slip faults) which, seemingly predate the gravity slides. These faults may have been the product of stresses in effect during expansion of the Proto-Atlantic Ocean. The slides and slices were formed during contraction of the Proto-Atlantic Ocean.
Field relations at the Milan Window demonstrate that the parautochthonous carbonates (megabreccia?) were emplaced prior to the transport of the slides and slices -- an important criterion in documenting the regional geologic history.

E edge of Milan Window.
Several exposures of Mt. Merino black shale on both sides of road almost to T.S.P. (black shale on S side of road).

Melange exposures on T.S.P. near intersection.

Everett Schist on both sides of road.

Everett Schist on E (left).

Crossing into Van Buren Slide
Crossing into Van Buren Slide near intersection with Knight Rd. Indian River green and red shales and cherts.

Germantown fm to S, Stuyvesant Falls fm to NW
Germantown gray-black shale in borrow pit on S side of intersection; Stuyvesant Falls Formation in cliff NW of intersection.

Indian River
Indian River green and red mottled slates near Tinkertown Rd.

Wappinger carbonate valley
Re-enter Wappinger carbonate valley at Pleasant Valley.

Rochdale limestone and dolostone on both sides.

STOP 10. Rock cut and fault along Penn Central R.R.
At the western end of the railroad cut is an apparent high-angle reverse fault with Late Cambrian Briarcliff Dolostone on the east and the Middle Ordovician Snake Hill Shale on the west. Note the gouge (mylonitized) zone along the contact. The question here is whether this is a bonafide high-angle reverse fault, east being the overriding block, or rather a carbonate block which has gravity slid into the Snake Hill mud; the illusion of a high-angle fault may have been created subsequent to sliding by rotation of the strata during an Acadian (Middle Devonian) folding episode.
The fault plane dips 75-80° E and there is no apparent drag here or anywhere else along the western margin of this carbonate block. At New Hamburg, along the railroad on the Hudson River, the fault plane dips 35-40° E. The absence of drag and variable dips of the "fault plane" tend to argue for a "block-in-shale" situation.

B7: PROGRESSIVE METAMORPHISM IN DUTCHESS COUNTY, NEW YORK
A. E. Bence
SUNY-Stony Brook
and
J. M. McLelland
Colgate University
Introduction
The purpose of this trip is to examine the development of regional progressive metamorphism within southeastern Dutchess County, N.Y. All stops, except the first, lie within the Clove 15' quadrangle (Fig. 1). Localities to be visited have been chosen in order to show a variety of mineral assemblages beginning with rocks at chlorite grade and proceeding eastward through the first sillimanite isograd. The majority of lithologies to be examined are pelitic with interbedded cherts and quartzo-feldspathic rocks. One stop will be made within units of the carbonate shelf sequence where calc-silicates may be seen. The implications of recent geochronological studies will be discussed relative to the geologic history of the area.

B7: PROGRESSIVE METAMORPHISM IN DUTCHESS COUNTY, NEW YORK

Mt. Merino member of Normanskill Fm.
Between here and Stop 1 the Mt. Merino member of the Normanskill Fm. is exposed at a number of localities in the surrounding fields.

STOP 1. Chlorite Grade - Roadcuts
The purpose of this stop is to display typical pelitic lithologies at low metamorphic grade (i.e. chlorite zone). Similar lithologies, though not necessarily identical stratigraphy, constitute the metapelites to be visited at later stops.
The east end of the cuts consists of typical red and green slates and phyllites of the Indian River member of the Normanskill Fm. At the west end of the cut black slates, phyllites, and greywackes of the Mt. Merino member are exposed. The contact between these two units occurs just at the western end of the red Indian River exposures. Some faulting appears to have occurred along the contact and a later northwestward dipping reverse fault, with associated fracture cleavage, further complicates relationships. These roadcuts are part of a small erosional remnant of a larger allochthon whose principal exposure lies just north of Freedom Plains, N.Y. and is well exposed in the vicinity of James Baird State Park (Fig. 1).
Mineralogically the red phyllites and slates consist of hematite-chlorite-muscovite-plagioclase-quartz. The green lithologies consist of muscovite-chlorite-plagioclase-quartz. These differences imply a variation in oxidation state whose origin is not well understood. Gradations in color occur along strike of the beds and suggest that the variations may be secondary in origin.
The eastern portion of the roadcut consists of several relatively large (λ = 50-60'), upright folds on which are developed a multitude of parasitic chevron folds. Fold axes trend N30-50E and plunge NE at between 10° and 60° with most of the steeper plunges on the north side of the road. The style of folding is of the rounded, chevron type with minor folds reflecting the symmetry of the larger structures. Late flattening appears to have occurred. Associated with these folds is an axial planar crenulation cleavage that strikes N30-50E and dips steeply to the northwest. Close inspection shows that the cleavage intersects an earlier foliation that has been folded by the upright folds. The earlier foliation is usually subparallel to bedding but large intersection angles have been found.
Excellent weathered exposures, and a good overall perspective of the folds in the roadcut, can be found by climbing to the top of the cut.
At the western end of the cut the Mt. Merino slates and phyllites have undergone extensive kink folding with associated axial plane crenulation cleavage which strikes N40-50E and dips steeply to the west. Presumably these kinks are of the same generation as the chevron folds in the Indian River. Greywackes within the Mt. Merino have deformed by buckling rather by kinking. Sedimentary structures can be seen within the greywackes and suggest that the section is not overturned.

Roadcut in green phyllites of Everett Fm.
Roadcut in green phyllites of Everett Fm. (presumed allochthonous) on south side of road. This outcrop exhibits minor structure evidence for at least four phases of deformation. Kink folding and crenulation cleavage are abundantly developed.

Quartz-breccia fault zone.

STOP 2. Biotite Grade - Black Walloomsac slates.
The slates are highly graphitic and often contain large amounts of pyrite. A strong N20W, 60E cleavage pervades the rocks and is related to N20W minor folds in the outcrop. These folds rotate an earlier foliation. Mineral phases present in the rock are: biotite-chlorite-muscovite and plagioclase-quartz-ilmenite. The principle reason for stopping at this outcrop is that biotite is developed macroscopically and is easily visible with a hand lens. Here we are very close to the biotite isograd. Note that the biotite flakes grow across the planes of foliation. Be careful to distinguish flakes of biotite from ilmenite grains.

Black, graphitic, sulfidic Walloomsac slates.
Large roadcuts in black, graphitic, sulfidic Walloomsac slates. Vein quartz is abundant in the outcrop. Proceeding down the hill, we enter the Clove Valley which is underlain by Wappinger carbonates of the shelf sequence.

Cuts on south side
Going up the hill note the cuts on the south side of the road.

STOP 3. Garnet Grade
Small parking area on south side of road.
(a) Walk back down hill to examine cuts passed as we drove uphill. These consist of black biotite rich schists and cleaved metagreywackes. The observer is asked to compare these lithologies with the Mt. Merino seen at Stop 1. The principal foliation is N60E and dips 45°S.
In coming eastward from Stop 2 we have passed over the garnet isograd. At this locality garnet is sparsely developed in the more westerly (downhill) outcrops of black, graphitic biotite schists. The mineral phases in these rocks consist of garnet-chlorite-biotite-muscovite-feldspar-quartz (Fig. 4a). Proceeding uphill, the amount of graphite decreases while quartz increases, and the rocks begin to resemble greywackes. Within these units garnet is principally developed in thin beds which probably represent pelitic members in a turbidite sequence.
It has not been determined whether these rocks are allochthonous or autochonthonous. They are shown on the New York State Geological Map (1973) as Austen Glen greywackes. This designation, or an assignment to the Mt. Merino, would strongly imply that they are allochthonous. Approximately 1/4 mile south of here the metapelites are found overlying either Poughquag quartzites or the lowermost, quartzite rich, portion of the Stissing. If the rocks are not allochthonous, then the Middle Ordovician unconformity bevelled to the deepest portions of the shelf here, while 1.5 miles to the west the Balmville and Walloomsac rest on the Copake Limestone which occurs at the top of the Wappinger Group. This is by no means an impossible situation, but serves to emphasize the nature of the unresolved structural problems in the area.
(b) Return to parking area and walk north along the old dirt road to the north of the highway. After approximately 200' climb up to the exposures on the east side of the road. These small ledges show an exceptional development of chloritoid. Black chloritoid grains of up to 1/8" in length can be seen growing in seemingly random orientation. Microscopically the chloritoids are clearly younger than the principal foliations but are deformed by kinking and crenulation.
The mineral assemblage in these rocks consists of garnet-muscovite-chlorite-chloritoid-feldspar-quartz. As shown in Fig. 5a, this assemblage is the result of a more aluminous bulk composition than in the rocks at 3a. Here biotite is absent and is separated from chloritoid in an AKFM projection by the garnet-chlorite tieline (Fig. 5a).
At least two major foliations are present in the outcrop. An early N30E, 40S foliations appears to be related to small, attenuated isoclinal folds defined by thin quartz stringers. This foliation is generally parallel to compositional banding. The dominant foliation in the rock appears to be later and trends N80E, 25S. This foliation is axial planar to a sharp disharmonic fold exposed just above the ledge which best displays the chloritoid grains. Note that this fold folds an earlier foliation.
(c) Return to the paved highway and walk east up the hill examining the interlayered schists and quartzose rocks. Chloritoid is still present in some of these units but grain outlines are not as sharp as at 3b. This may be the result of the onset of a chloritoid consuming reaction. Biotite and chloritoid are still mutually exclusive and remain separated by the tie line garnet-chlorite. Although chloritoid is still present in some layers, most of the schists consist of garnet-chlorite-biotite-muscovite-feldspar-quartz. These lithologies are similar to the rocks at 3a, and chloritoid is unable to form because the bulk compositions are not sufficiently rich in aluminum (Fig. 5a). This serves to emphasize the control of rock chemistry on the development of chloritoid in the area.

STOP 4. Staurolite Grade
Low, rounded outcrop on the north side of the road.
These rocks are approximately along strike (N20E, 30E) with the chloritoid bearing schists at STOP 3b. Here we are at somewhat higher grade and staurolite is developed in thin section. The overall mineral assemblage in these rocks is (Fig. 5b). The presence of five ferromagnesian phases is clearly in violation of the phase rule and this assemblage cannot be in equilibrium. This locality marks the lowest grade at which staurolite is found and the highest grade at which chloritoid is stable. Note the coexistence of biotite and chloritoid both of which are visible in hand specimen. Clearly the tie-line chlorite-garnet is in the process of being broken by biotite-chloritoid. Simultaneously chloritoid is participating in a staurolite forming reaction.

Poughquag Quartzite on the south of Rt. 55.

Enter Edward R. Murrow Park for lunch.
The exposures in the park are Balmville limestones and Walloomsac schists.

STOP 5. Kyanite Grade up hill by power line
Park at dead end and walk up the dirt road, past a house, and continue along the footpath. The valley here is underlain by Balmville Limestone. After approximately 1/4 mile the path crosses beneath a power line. Turn east up the hill to exposures of staurolite-garnet-biotite-muscovite-quartz-feldspar schists (Fig. 5c). These rocks are typical of staurolite rich schists in the region. Good penetration twins of staurolite can be found. Kyanite appears to be absent at this locality, and this is probably due to differences in bulk rock composition (Fig. 5c). The outcrop here contains several large, recumbent isoclinal folds. One of these is dominant and its axial region is exposed near the top of the outcrop. The axial plane strikes N60E and dips 20° S while the axis trends N30W and plunges 10° N. however, the exposure may be out of place. An earlier foliation, defined by micas, has been folded by this structure.

Hudson Highlands.
Turn east and head uphill through Precambrian gneisses of the Hudson Highlands.

Precambrian/Paleozoic contact
Contact between the Precambrian and black, rusty Paleozoic schists (Walloomsac?). Balk (1936) mapped this contact as a reverse fault. Ratcliffe (pers. comm.) has suggested that the absence of the carbonate section may be due to the lower Middle Ordovician unconformity. Minor structures are consistent with Balk's interpretation.

STOP 6. Kyanite Grade - long roadcuts
The rocks in these long roadcuts have been mapped as Walloomsac schists (N.Y. State Geological Map, 1973). Whether they are, or not, is open to question. Regardless of stratigraphic uncertainty, the lithologies are dominantly pelitic with biotite rich schists predominating. Quartzose and granular quartzofeldspathic layers and lenses are interlayered with the schists and serve to define early isoclinal folds. The dominant cleavage trends N30-40E and dips approximate1y 50°S. This cleavage is axial planar to tight northeast trending folds which fold the earlier isoclinal folds whose general trend is also northeast. An earlier foliation is associated with these isoclines. In places the second generation folds have been flattened into isoclines. Minor folds associated with these give opposing senses of rotation as the roadcuts are traversed along their length and suggest that the entire roadcut has been telescoped by the second generation folds. A third of open N-S folds is present and associated with kinking and crenulation cleavage in the rock.
Mineralogically the schists generally contain biotite-garnet-kyanite-muscovite-feldspar-quartz. The kyanite appears as 1/8"-3/4" blue blades growing without orientation within the schists, and is particularly concentrated within more pelitic layers, many of which have thickened on the noses of folds. This gives rise to pod like areas that are extremely rich in kyanite. These can be examined to best advantage on the top of the roadcut where weathering has made the kyanites most visible. The metamorphic grade observed here is the same as at Stop 5 but staurolite is rarely observed in these rocks. This may be attributed to bulk compositional differences between the two localities (Fig. 5c). The rocks here are more magnesian than at STOP 5 and staurolite is generally excluded from the phase assemblage.
In addition to kyanite rich layers certain quartzose bands are extremely rich in garnet. Hornblende bearing pods are also present and represent more calcic bulk compositions in the original sediment. Biotite from a biotite-kyanite assemblage here gives an 40Ar/ 39Ar plateau age of 414 million years.

Roadcuts in the Walloomsac black schists.
A sharp anticline brings the Balmville limestone to the surface near the east end of the cut. This outcrop is situated near the hinge of the Harlem Valley Syncline.

Roadcuts in the Balmville Limestone.
Here the Balmville is directly overlain by Walloomsac black schists.

Walloomsac calc-silicates and Balmville Limestone.
The Harlem Valley can be seen directly ahead. We are now proceeding into the overturned, eastward dipping limb of the Harlem Valley Syncline.

Upper portion of the Wappinger Group
Calcitic marbles of the upper portion of the Wappinger Group are exposed to the south of the highway.

STOP 7. Very large roadcuts in the Briarcliff Dolostone.
This stop is the same STOP 7 in McLelland and Fisher (this volume), and the structure of the cut is discussed in that article. 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. The most noteworthy example of calc-silicate development occurs close to the top of the roadcut near its eastern terminus. Here a two foot wide layer consists almost entirely of extremely coarse tablets, blades, and rosettes of white tremolite. The layer can be followed for well over 50 feet. In adjacent layers diopside tablets appear to be the only calc-silicates developed. Presumably this represents a very steep gradient in PH2O and a local system effectively closed with respect to the water migration across layers.

Briarcliff Dolostone
Low outcrop of Briarcliff Dolostone on the north side of Rt. 55. This outcrop contains outstanding examples of perfectly formed diopside tablets.

STOP 8. Sillimanite Grade
Roadcuts in coarse, muscovite rich schists.
Large garnets are developed. Sillimanite is present in this outcrop but has not been recognized in hand specimen. Tourmaline bearing pegmatites occur and suggest the onset of anatexis (Table 2).
Displayed within the roadcut are numerous examples of disharmonic folding in which the more competent quartzo-feldspathic units have broken and rotated. Early isoclinal folds may be seen. Many of these have attenuated limbs. Rootless isoclinal folds occur.

B8: ALLUVIAL AND TIDAL FACIES OF THE CATSKILL DELTAIC SYSTEM
by
Kenneth G. Johnson
Skidmore College
Within the uppermost Middle Devonian and lowermost Upper Devonian rocks of eastern New York State there occurs a remarkably complete spectrum of ancient sedimentary facies (Johnson and Friedman, 1969; Johnson, 1970, 1972, 1976). These beds, which evolved during a transgressive pulse in the building of the great Catskill deltaic system, are part of a 3000 meter sequence that constitutes the standard for the Devonian System of North America (Figs. 1 and 2). They are exposed at the northeastern end of the Allegheny Synclinorium, are essentially undisturbed and, for the most part, very fossiliferous. Laterally transitional between those beds that are clearly of marine origin and those that are clearly non-marine are sandstones and shales that have sedimentary structures, lithology, geometric relationships with adjacent units and biogenic structures that indicate that they evolved in tidal environments generally similar to those of the modern Wadden Sea.
The purpose of this trip is to outline evidence for assigning depositional environment interpretations to these non-marine and transitional clastics and to offer their associated characteristics as recognition criteria for rock units developed in other tectonic delta complexes (Friedman and Johnson, 1966) at other times in the geologic past.

B8: ALLUVIAL AND TIDAL FACIES OF THE CATSKILL DELTAIC SYSTEM

Cherty Onondaga Limestone exposures.
ON LEFT - colonial house, construction material Lower Devonian limestone.

Onondaga cherty, fossiliferous limestone.
Deep roadcut in Onondaga cherty, fossiliferous limestone. AHEAD - view of Catskill Front. The Front marks the eastern margin of the Catskill Mountains. It is cut by several narrow stream valleys (cloves) in which there are excellent exposures of Middle and Upper Devonian Catskill lithofacies. We will climb Kaaterskill Clove and observe rocks along the Rip Van Winkle Trail

Roadcut in cross-bedded, blue-gray sandstone.
Local term for this rock type is Bluestone.

ON LEFT Old, inactive quarries in Bluestone.

ON LEFT In distance, view of Kaaterskill Clove.

Cross small creek.
Rapids and low waterfalls in bed of creek due to well developed, horizontally bedded Bluestone ledges.

STOP 1. Gloria Dei Church (Episcopal)
This church, constructed in the late 19th Century, was built of fieldstone, most of Which is of local bedrock lithologies. The most significant of these are (1) polymictic pebble conglomerate, (2) grayish green, immature, medium-grained, sandstone, and (3) dark red, very fine grained sandstone and siltstone. In some respects this is as good an outcrop as any that you will see today.

Cross Kaaters Kill and begin climbing clove.
Just downstream from this bridge are very well developed pot holes and water falls, where the stream flows over Bluestone ledges.

Red and green Catskill lithofacies.
ON RIGHT, across Kaaters Kill - inter-beds of red and green Catskill lithofacies.

ON LEFT, up clove -Twilight Park
Twilight Park, a private preserve that was very fashionable in the late 19th and early 20th Centuries. It is still private, but less fashionable. The preserve is the type locality of the Twilight Park Conglomerate, the coarsest of the Catskill lithofacies rocks. The conglomerate appears to represent an ancient mountain front, braided stream deposit. You will see it in outcrop at Stop 3.

Road swings sharply left.
Cascade on right formed where tributary of Kaaters Kill flows over sandstone ledges.

STOP 2. View down Kaaterskill Clove
From this point it is possible to look east down Kaaterskill Clove. The cross-sectional profile is typical of high-gradient streams that are engaged in active vertical erosion. The Kaaters Kill is considered to be an excellent example of a short, high gradient stream that has managed to capture the headwaters of a longer lower-gradient stream flowing in an opposite direction. The elbow of capture is at Haines Falls, just west of this observation point.

Route 18 leading to North Lake Campsite,
Route 18 leading to North Lake Campsite, former site of Catskill Mountain House. The Mountain House, a resort hotel, was situated near the top of the Catskill Front, some 700 meters above the Hudson River. Exposures of cross bedded gray, conglomeratic sandstone and conglomerate may be seen on the trails around North Lake Campsite.

AHEAD - Hunter Mountain ski area.

STOP 3. Outcrop of cobble conglomerate
Outcrop of cobble conglomerate at base of one of Catskill lithofacies alluvial channels. This basal lag concentrate was apparently deposited quite near its source area. It is by far the coarsest exposure that you will see today.

ON RIGHT -Catskill lithofacies.

ON RIGHT -Catskill red beds.

Pratt Rock Park on outskirts of Prattsville.

STOP 4. Hardenburgh Falls
Walk northeast along unsurfaced side road to Hardenburg Falls.
At this point Bear Kill flows into Schoharie Reservoir. Beds here are assigned to the tidal channel and tidal flat facies. The tidal channel facies is represented by gray, cross-bedded, fossiliferous sandstones and the tidal flat facies by very dark gray, very thin-bedded, in part conglomeratic, shales. Lag-concentrates in both facies are rich in shallow marine brachiopod shells.

STOP 5A. Alluvial channel sandstone
On east side of road, exposure of alluvial channel sandstone resting on red over bank shale.

STOP 5B. Gray, cross-bedded sandstone
On east side of road, exposure of gray, cross-bedded sandstone of tidal channel facies with lag-concentrates of shallow marine spiriferid brachiopods.
BE VERY CAREFUL. THIS IS A NARROW SPEEDWAY WITH POOR VISIBILITY.

On right, in distance - large quarry
On right, in distance - large quarry from which much of stone for Gilboa Dam was taken. Completion of dam impounded waters of Schoharie Creek, forming Schoharie Reservoir, a part of New York City water supply system.

View north down Schoharie Valley.
Note even crest of hills flanking valley, a result of stream dissection of nearly horizontal Devonian strata

STOP 6. Display of seed-fern stumps
Display of seed-fern stumps taken from quarry just to southwest. Some 200 specimens were found during the quarrying operation. These seed-ferns are thought to have grown to heights of some 18 meters in swamps along the seaward margin of the Catskill alluvial plain during late Medial Devonian time. They were buried during a minor oscillation of the marine shoreline in tidal channel or bar sand deposits.
2013: Stumps were apparently moved here, from the other side of the bridge, as the excavation took place in 2010...OHM

STOP 7A. Alluvial channel sandstones
These alluvial channel sandstones mark the top of an excellent section of some 185 meters, consisting almost entirely of rocks of alluvial origin. Many of these sandstone ledges show an interesting upward progression of change in texture and sedimentary structures.

Hamilton Group
To left (north), in distance, dip slopes of Hamilton Group strata.

Tidal channel facies.
ON RIGHT - high on outcrop - tan sandstone, much lighter in color than sandstone in remainder of exposure, assigned to tidal channel facies.

STOP 7B. Over bank facies root stigmaria
At the driveway are alluvial overbank facies root stigmaria and a highly calcareous overbank "evaporite" bed. A short distance downhill is a compound alluvial channel and laterally equivalent overbank silt stones.

Catskill lithofacies
Beginning of series of road cuts channel and overbank rocks in Catskill lithofacies

B9: ENVIRONMENTAL GEOLOGY and VISUAL POLLUTION OF THE LLOYD NUCLEAR POWER PLANT SITE
by
Stephen J. Egemeier
Department of Geological Sciences
State university of New York College at New Paltz
A History of Site Study
In November 1971 the N.Y. Atomic and Space Development Authority released an anonymous report by Dames and Moore (a consulting engineering firm) entitled : "Consultation and Geologic Evaluation Site Suitability Studies: Hudson River Valley between Albany and Newburgh, New York." The report studied nine sites, two adjacent to the present Lloyd site. Of the nine sites, 5, or more than half, are rated as most favorable for additional study.
Starting in March 1975, R. Waines and I decided to have a quick look at the regional geology of the site. We started by walking the Dames and Moore cross section and studying all outcrops within a few hundred feet of the trace of the section. Many man days were spent and over 100 observations recorded for the 3 mile section. We then checked critical outcrops mentioned by Dames and Moore and did a general reconnaissance of the area. A broad picture has emerged and is shown in our tentative cross section in Fig. 5.
The aim of this field trip is to show you some of the major points of geologic interest and also show some of the areas of controversy. There is ample room for supposition and argument until adequate study is completed.
The site geology is difficult to determine due to a lack of good marker beds, a lack of diagnostic fossils, and lack of continuous outcrop. Recently, many people have started working out the geology, however, a considerable effort will be required to gain a detailed understanding of the site geology. There is still a lot to be done, for example, as yet there is no published detailed stratigraphic column of the site area. Up until now there had been no economic reason to study this area.
Harvey K. Flad
Vassar College
Introduction
The analysis of the environmental impact of a noxious facility implies the need for assessment of aesthetic and social impacts as well as the physical impact upon the land, air, water, and biota. Aesthetic impacts, such as upon the visible scene, have not been studied in detail for the environmental impact statement of the siting of a nuclear power plant at Lloyd, N.Y.
This lack of detailed concern is unfortunate: the changes due to the viewscape are obvious and of a degree of magnitude which demand their attention. Although the assessment of aesthetics is complex and fraught with problems of subjectivity, nevertheless transmission tower and power plant design and siting must be implemented in consonance with the overall human environment, indeed, Federal and State legal rulings reflect an increased awareness and justification tor aesthetics as a form of environmental control. (Flad, 1974) Measurement of aesthetic impact of nuclear power plants is possible (Burnham, 1974). This paper and field trips will deal with some of the outstanding aesthetic concern (cooling tower height and plume, transmission pylons and rights-of-way, and historic and cultural sites) with respect to varying viewsheds of the Lloyd site viewscape.
Conclusion
A concern for the aesthetic impact of a nuclear power generating facility is not a secondary matter. Not only is it mandated by the Nuclear Power Regulatory Commission in pursuance of the goals of NEPA, but it is an appropriate measure of the goals and purpose of the electric utility or state agency which originates the proposal for a site and employs a consulting firm to do the EIS. Some concern was shown for the biotic impact upon the John Burroughs Sanctuary (National Audubon Society, 1974), but its aesthetic impact on this historic site and on the historic sites along the Hudson River (Roosevelt, Vanderbilt and Ogden Mills Estates) was less apparent. The accompanying road log to the field trip details some on the viewshed and aesthetic amenities of the Lloyd site and its impacted Mid-Hudson region.

B9: ENVIRONMENTAL GEOLOGY and VISUAL POLLUTION OF THE LLOYD NUCLEAR POWER PLANT SITE

Typical urban strip
On the way, one may notice typical urban strip development, including two important historical buildings as noted. The West Indian grocery on the right is an urban landscape indicator of ethnic change in the Poughkeepsie Central Business District.

Glebe House
The Glebe House is on the right. Built in 1767 by the Poughkeepsie and Fishkill congregations of the Episcopal church for their minister, it is the oldest brick house in Dutchess County. The first permanent Episcopal minister, Reverend Beardsley, was exiled during the Revolutionary War for his Tory sympathies. It is now maintained by the Dutchess County Historical Society and the Junior League of Poughkeepsie.

Clinton House
The Clinton House is a State historic site, named in honor of the first governor, who made his headquarters in Poughkeepsie when it was the temporary state capital from 1777 to 1783. Originally built c.1765, it was rebuilt and enlarged in 1783 by Udny Hay, purchasing agent for the state, with assistance from artisans from the Continental Army sent by General Washington.

STOP 1. College Hill Park.
The largest park in the city of Poughkeepsie, College Hill Park is located on the highest point in the city (375 feet). Excellent views south and southwest of Poughkeepsie and its environs, as well as the bridge and the Hudson River; farther south the Fishkill or Breakneck Ridge can be seen. West and northwest lie the Catskills; the Lloyd power plant site lies among the hills to the northwest. The park is named for a school which existed at this site in the mid-nineteenth century. After the school and subsequent plans to use the buildings had failed, William W. Smith, of Smith Brothers cough drops in Poughkeepsie, donated the land to the city in 1892. The Greek Doric designed stone solarium on the crest of the hill was built in 1935-6.

Open reservoir on left.
This open area affords the best view northwest across the Hudson River towards the Lloyd site. The open reservoir was formerly the main water supply of the city.

Michael's (Joseph's since 2011) Restaurant on right.
This building was used as the tea room for Val-Kill Industries, established in 1927 by Mrs. Eleanor Roosevelt. Eleanor Roosevelt's cottage (Val-Kill) still exists one quarter of a mile east of this point (on a dirt road 150 feet north of the intersection of Route 9G and Creek Road). At the cottage Mrs. Roosevelt organized a cottage crafts industry which attempted to reintroduce the crafts of furnture making, pewter smithing and hand-weaving as a local economy. The cottage is presently under consideration for inclusion in the Federal Register as a National Historic Landmark.
If a power plant is built at Lloyd, the electricity will be shipped by high tension transmission lines along a power line corridor that traverses this property; the lines and pylons will dominate the Val-Kill skyscape.
2013: In 2011 Joseph & Diana Wilson open Joseph’s Steakhouse as a classic New York style Steakhouse in Hyde Park. The Steakhouse property was formerly owned by Eleanor Roosevelt as the Val-Kill Tea Room.

Homestead Market on the right.
This property until recently was the last remaining dairy farm in the Poughkeepsie-Hyde Park urban area.

William Stoutenburgh House, on left.
One of the only two remaining early Dutch stone houses, built probably in 1750 by William, son of Jacobus Stoutenburgh, the first settler of Hyde Park. It was fired upon by British ships in October 1777. Otto Berge, who was foremost maker of antique reproduction furniture at Mrs. Roosevelt's Val-Kill furniture shop, lived in this house for over forty years until 1975.

STOP 2. Vanderbilt Estate
The Vanderbilt Estate was built by the grandson (Frederick) of Cornelius (Commodore) Vanderbilt in 1895. The building is a classic by the architectural firm of McKim, Mead & White.
A short walk from the parking lot to the mansion and surrounding lawns. From the edge of the bluff a magnificent view west across the Hudson River.
Viewing southwest, one can have a clear sight-line towards the Lloyd site, exactly 3 miles away. All four stacks will be visible.

View west and northwest of the Catskills.

Hyde Park Playhouse
Directly across the exit are the former estate horsebarns, now the Hyde Park Playhouse, famous for summer theater.
2013: Burned down on April 28, 1987.

Bergh-Stoutenburgh House on left.
The second of the two remaining stone houses in Hyde Park, built before the Revolutionary War. Its gambrol roof is unusual. Now recycled and occupied by the Green Frog dress shop.
2013: Later, home to Edo Sushi, a Japanese restaurant. The restaurant closed its Hyde Park location and moved to nearby Poughkeepsie in the fall of 2012. The Bergh-Stoutenburgh House is currently unoccupied.

Cleared Lot
On the left (next to Gasland gas station) is a cleared lot ... all that remains of the third of the previously three existing pre-Revolutionary stone houses.

STOP 3. F.D.R. home and museum.
The birthplace of the 32nd President of the United States, and home for himself and family. The 94 acre site contains a museum and library as well as the graves of both Franklin and Eleanor Roosevelt. Originally built c. 1826, the wings were added in 1915 by F.D.R.
The view from this home of 3.1 miles of the Lloyd site is only slightly obscured by a range of hills in the Lloyd region. Stacks numbered 3 and 4 of the proposed Lloyd site plan would definitely be seen in any case.

Barkers shopping center on right.
After intensive discussion, stone walls were preserved.
2013: Now called Hyde Park Mall, it was renovated in 2010.

Culinary Institute of America on right.
Formerly St. Andrew's Novitiate, a Jesuit seminary since 1903. American Trappist Monk Fr. Thomas Merton, author of The Seven Storey Mountain and numerous poems and essays, is buried here. Purchased by the C.I.A. in 1970 as a college for fine chefs.

Hudson Valley Psychiatric Hospital on the left.

Marist College on the right.

Austin Glen formation
The curved roadcut just west ot the bridge reveals a section interbedded shales and graywackes mapped as Austin Glen formation on the 1970 N.Y. State geologic map and by Dames and Moore, 1975. On the west (left) side of the cut several faults are visible. Note that an individual bed may vary in thickness even over short distance. We will see a lot ot outcrops that are frustratingly similar to this one.
Good marker beds are non-existent and what poor markers there are are useful only in very small areas. Fossils are rare and usually nondiagnostic. Thus geologic mapping in the Lloyd area is a slow and arduous task. All the rocks in the Lloyd area are Ordovician in age.

STOP 4. Steeply dipping graywacke.
On the 1970 N.Y. State Geologic map this is mapped as Quassaic although this sequence differs trom the map's description of the Quassaic. Dames and Moore map this outcrop as Schenectady Formation, just south of here, along strike, they map the same rocks as Quassaic Sandstone. These rocks may be Quassaic or may overlie the Quassaic.
This outcrop is a section of the east limb of an asymmetric syncline with it's east limb overturned. On the east and of the outcrop the rocks dip east steeply and are overturned. On the west end of the outcrop the rocks dip steeply west and are right-side-up. The fold axis is just west of here, perhaps along the Black Creek (i.e. near the bridge).
If we were to travel to the west we would not see a repeat of the strata exposed here, but would see mostly shale. Thus it is assumed that a fault is buried beneath the till along Black Creek. The fault could be a thrust dipping east that formed contemporaneously with the folding or it could be a steeply dipping normal fault dipping east as shown by Dames and Moore, 1975. Minor faults in this outcrop might suggest this.
I prefer the former interpretation and Dames and Moore prefer the latter. As the fault is buried neither answer can be proven at this time.

East dipping shales
Note shales on right side of road, gently dipping towards east, also outcrops on left in pasture of east dipping shales.

Revolutionary age cemetery on left.

Cross Black Creek.
Note waterfall on right. Outcrops of gently eastward dipping shales with interbedded graywacke.

STOP 5. West limb of a syncline
We will stop on the east shore of Chodikee Lake and hike to the east across the west limb of a syncline to the axis of syncline. STOP 4 was on the east limb of this same fold.
To the west of where we will park the busses is Chodikee Lake. Based on outcrop along the south shore of the lake (near the waterfall for example) it appears that the bedrock under the lakes is mainly shale with some interbedded graywacke. The low ridge just west of the lake is mainly massive graywacke. The ridge is bounded on the east by a shear zone that follows a swampy valley.
As we walk east you will note that the exposed bedrock is mostly graywacke. Shales are found in some of the valleys beneath the soil. The axis of the syncline is just west of a cliff formed by graywackes of the east limb of the fold. If we were to continue to the mountain summit we would climb valley and ridge topography with very little shale. Thus the shales beneath Chodikee Lake do not seem to repeat on the east limb. This again suggests that the fold is faulted. The extreme asymmetry of the fold and the general pattern of thrusting from the east suggest that the fault would be a reverse fault.
The rocks that crop out at the axis of the fold at this point are the youngest rocks of the Lloyd site. Their exact age is not certain as diagnostic fossils have not been found in this area. I have found fossils in float and am hopeful that I will find some in place.

STOP 6. View across lake
View across lake towards site of nuclear power plants and cooling towers, less than one mile NW of east shore of Chodikee Lake. Notice meteorological tower directly west (at southern end of site). The tower is 90 meters tall; thus the cooling towers will be almost two times as tall, as well as much more massive.

Land use that may be affected
As examples of the agricultural land use that may be affected by land pressures due to growth, or to climatological change; note the vineyards and orchards to right side of road.

Outcrop on left.
Outcrop shows slightly metamorphosed slaty shales and siltstones, with foliation steeper than the eastward dip.

Agricultural land use typical of region
Note new plantings at apple orchard on left

Examples of architectural individualism
Note house with sculptured gargoyles on left, and building with used car parts sign on the right side of Route 9-W.

Outcrop of shales.
Stop sign, Turn left onto Route 9-W northbound. Outcrop on immediate left at stop sign is another good example of shales.
2013: Now there is no access to northbound lane here. Hence, we return along North Road to where we can get into the northbound lane.

Town of Esopus sign on right side of highway.
Two nuclear plants are projected to be sited on the town line between Esopus and Lloyd, less than two miles directly west. Such exact siting is to spread the economic impact over two towns.

Mother Cabrini Retreat House on right.
Many former Hudson River estates have been converted to monasteries, seminaries, or retreat housed by various churches and orders, such as the Holy Cross, Christian Brothers, and Marist Brothers. Excellent views of the Hudson River valley looking eastward from these properties.

Outcrop on right. Extremely steeply dipping.
Excellent example of an overturn, note ripple marks overturned.

STOP 7. LUNCH STOP
At driveway (entrance) to Cabin of John Burroughs, noted Catskill naturalist and author of many books on natural history in the 19th Century, stop for short walk to lunch stop area.
Bus will stop briefly to offload passengers for a short walk alongside outcrops alongside road and will meet us a Gordon Preserve Park (along Black Creek in the Gordon Memorial Woods). Watch it -- Poison Ivy is abundant in this area.
The buses will stop near the crest of the ridge where the bedrock is clearly overturned. We will walk down the road to the Black Creek where several ledges in the stream dip south. Just west of the stream bedrock dips east. The Black Creek is following the axis of the syncline along this reach. We are on the axis of the syncline at a point stratigraphically much lower than at the Highland Training School, STOP 5. This is one of the most accessible places to view the syncline. Even so, we cannot trace beds from one side of the fold to the other because of a fault.
Southeast of here on the road that parallels the creek is Villa Valley. At Villa Valley another fault is exposed in outcrop. It dips east at a slight angle to bedding and is apparently a thrust. It strikes north and crosses Floyd Ackert Road about half a mile east of here.
Lunch can be eaten along the banks of Black Creek or the dammed up swimming pool on the creek. Tour participants are encouraged to seek additional evidence from neighboring outcrops, or commune with nature in the manner of John Burroughs.

Note very gentle dips on outcrops.
Popletown Road becomes a gravel road as it steeply climbs 350 feet to the peak of Shaupeneak Mountain.

STOP 8 Western Union communications tower
From the clearing afforded by the Western Union communications tower facilities, note the view South and Southwest of the Lloyd nuclear site. The nuclear plants and cooling towers will be approximately four miles directly south from this peak, in the center of the presently relatively unspoiled and aesthetically pleasing view.
There is an OUTHOUSE available at this stop.
A short walk to various outcrops on peak; especially noteworthy are the red cherts. Return to bus for trip hack down mountain to Old Post Road.
This stop is at the northern end of the syncline we saw at Black Creek and the Highland Training School. We are several thousand feet stratigraphically lower than we were at the training school.
The stratigraphically lower part of the fold is far more gently folded and is not overturned. Several north striking shear zones cut the structure and at least one can be seen in outcrop along the cliff to the east.
Just north of a former community antenna system rocks crop out that fit the description of Quassaic Quartzite as given on the Geologic Map of New York, 1970. They are overlain by thousands of feet of rocks that do not fit the description. The description from the 1970 N.Y. State Geologic Map key is as follows:
"Quassaic Quartzite - thick bedded red and green quartzites and greenish-gray sandstones, conglomerates with pebbles of red and black chert, shale and limestone."
Dames&Moore in their 1975 report have changed the description of Quassaic. Their map key states:
"Quassaic Sandstone: Grey to brown calcareous protoquartzite and subggraywacke with occasional conglomeratic zones of limestone, chert and shale pebbles."
The point of this trip is not to pick hones over stratigraphic nomenclature, but to get a general idea of the environmental geology of the Lloyd Site. The proposed nuclear power plant complex represents the first time there has been significant economic reason to work on the geology of this region.

Historic one room school house
Note historic one room school house building on right which has been recycled into a home.

STOP 9. Sturgeon Pool of the Wallkill River.
Sturgeon Pool is part of a hydroelectric installation of Central Hudson Gas andElectric Corporation.
Dames & Moore 1975 have mapped the northern half of the pool as Snake Hill formation. The eastern shore at the pool is massive graywacke and the hill on the west is largely shale. Thus on the 1970 N.Y. State Geologic Map the eastern shore is mapped as Austin Glen and the west as Normanskill (Snake Hill).
As an example of the visual imprint of electric power transmission lines and pylons in the skyscape, note the 345 kV lines across the lake at the spillway. Lines which carry greater loads (765 kV) require higher pylons and are therefore even more apparent in the landscape and skyscape.

Outcrops on left
Shales with interbedded thin graywackes.

1816 stone Church on right.

Thick graywacke beds interbedded with shale
As we drive south along Sturgeon Pool, you will note thick graywacke beds interbedded with shale. Dames & Moore show a thrust fault relationship between the graywackes and shales.

STOP 10. Electric power substation
Central Hudson Gas and Electric Corporation electric power substation
Offload from busses in the C-H parking lot and walk down Route 213 on left side of road. WATCH FOR TRAFFIC. A small fold is in evidence, as well as interesting facies changes of graywacke and shale. Note as you walk along to road cut that at least one 2 ft. thick massive graywacke bed develops shale interbeds to the west. Generally, there is a facies changes in the Lloyd area with graywackes on the east and shales to the west. We will walk up the bank and through the woods to get to a unique outcrop. There is no trail so watch your step.
This outcrop is described by Dames and Moore in the 1975 report on page 31 as follows:
"4.1 Dashville thrust
"Perhaps the most spectacular and (from a classical viewpoint) unexpected structure in the region is the Dashville thrust. This feature is exposed along Rt. 213 between Rt. 32 and Rifton, and is best preserved in the hillside below the Woodcrest School. There, upward from road level, occur (1) moderately folded Snake Hill sandy shale, (2) 20 ft. of thrusted slices of Schenectady Formation and Quassaic sandstone, (3) three feet of tectonically mixed Snake Hill and Quassaic and, (4) about 200 ft. of Snake Hill Formation. The investigators feel that (1) the amount of evident thrusting (2) the observed intermixing of Quassaic and Schenectady, (3) the thinness of the characteristically thick Quassaic-Schenectady section, and (4) the overlying zone of mixed Quassaic-Snake Hill all argue for a tectonic sliver of Quassaic and Schenectady caught in a major thrust of Snake Hill over Snake Hill."
The names used by Dames and Moore refer to lithology as follows (abstracted from their map key):
Schenectady formation: thinly bedded subgraywacke interbedded with siltstone and silt-shale.
Quassaic sandstone: Protoquartzite and subgraywacke with occasional conglomerate zones.
Snake Hill Formation: Silt and clay shales interbedded with thinly bedded siltstone.
Look at the outcrop and come to your own conclusions. Is what you see due to thrusting or some other cause?
Continue to "Perrines Bridge," an old covered bridge across the Wallkill circa 1844 (Ulster County Historical Site).

STOP 11. Possible seismicity along linear?
Events similar to earthquakes have been reported by several homeowners in this area. The reports are only from those who live along a line parallel with the base at the ridge just east ot the road intersection. The reports seem to be aligned along a N-S linear feature that shows up on landsat photography. The linear also shows up on topographic maps and on the ground as a series of aligned valleys. This linear is one of the more noticeable of s e veral subtle N-S linears that cross the site. This linear is apparently at least 8 miles long.
Where one of the linears crosses Shawpeneak Summit sheared graywackes crop out on the southeast side of a valley that marks the linear. Dames and Moore drill hole 2 is 500 ft. east of the linear. The hole was drilled to 249 ft. and several broken zones were reported. It seems most reasonable to conclude that his linear is a fault.
People who live along this alignment have reported events that may be earthquakes. The linear passes through one of the proposed nuclear power plants. A summary of the reported events are listed in the appendix.

ASDA (ERDA) Meteorological Station on the right.
Climatological data is gathered at ground level and from the 90 meter tower noticeable from the road.

STOP 12. Sorbello's greenhouses and onion farms
Situated on the deep rich muck soils, Sorbello's greenhouses and onion farms are located in the very heart of the proposed nuclear site at Lloyd. The land use plan proposes the first two plants and cooling towers to be located just to the north in the same swampy soils. View south and notice the height of the ASDA-ERDA meteorological tower (90 meters) and recall that the cooling towers planned for this site are almost two times as tall and massive enough at their bases to essentially fill the valley east-west.

B10: ENGINEERING AND ENVIRONMENTAL GEOLOGY OF THE HUDSON VALLEY POWER SITES
William D. Lilley
Associate Generating Facilities Analyst (Geology)
Office of Environmental Planning
NYS Department of Public Service.
Empire State Plaza
Albany, New York 12223.
and
Claudia Assini
Geologic Consultant to the NYS Geological Survey
for the Indian Point Project.
Introduction
The four main types of electric generation facilities that will be available in the next 25 years are coal, oil, nuclear and hydro. Each type has significant environmental impacts requiring detailed geologic and environmental studies. The purpose of this field trip is to identify some of the geologic and environmental considerations involved with siting various types of facilities.

STOP 1. Danskammer and Roseton, Marlboro, New York
(1) Danskammer - Central Hudson Gas & Electric Corp. Plant - Oil Fired - 531.9 MW - 66.3 Acres Plant Site
Units 3 and 4 of the Danskammer Point Generating Station are the subject of a notice of intention by the Federal Energy Administration to issue a prohibitive order that would require conversion of those units from residual oil to coal.
Unit 3 was first placed in commercial service in October 1959 and Unit 4 in September 1967. Central Hudson currently has $57,000,000 invested in the two units; $5,000,000 represents the cost of converting these units from coal-firing to oil-firing in 1970 and 1971.
These units were originally designed with coal as their primary energy source. In the late 1960s, however, because of the rapidly rising cost of coal, the deteriorating quality of the coal economically available, coal delivery problems, increasing costs associated with coal unloading and handling and ash disposal, increasing concern about the environmental impact of coal burning, and the very attractive prices for fuel oil being offered by some of the major oil companies, the decision was made to convert these units to oil firing. At that time the oil companies indicated to the company that oil prices would be stable for a long time and that ample oil supplies would be available. Indeed, after competitive bidding, the company entered into an advantageous contract for fuel oil at a fixed price; that price prevailed from 1968 to the oil embargo in 1973.
Because of the foregoing factors and the severe space limitations at the station, the company decided that the conversion from coal to residual oil would be permanent, with no consideration for reconversion to coal-firing. Consequently, major modifications were made that resulted in these units becoming exclusively oil-fired.
The major problems of air quality impact and waste disposal associated with conversion have not yet been resolved. At present there are air quality violations in the area of the plant, and conversion to coal could only worsen this situation. The Environmental Protection Agency has yet to make a decision on the FEA coal conversion notice.
(2) Roseton - Central Hudson Gas & Electric Corp. Plant - Oil Fired - 1242 MW -133 Acres in Land Use
Environmental Impacts:
(a) Aquatic and Water Quality The plant is under EPA orders requiring cooling towers. The company has requested a variance to prepare studies to prove the impact of cooling water intake and discharge location and operation is insignificant.
(b) Air Quality Violations of the Federal primary ambient SO2 standards have occurred in the vicinity of the plants. The New York State Department of Environmental Conservation has ordered Central Hudson to burn lower sulfur fuel costing $8 million more per year. Public Service Commission staff believes that the severe downwash problems due to the short stacks, compounded by the high terrain at these facilities, are creating the air quality problems. The stacks were designed in response to a State agency request to limit the aesthetic impact of the facility.
(c) Noise Numerous complaints have been made about noise generated by the Roseton Station. The noise problem is a result of the short stacks. The company has attempted to increase exit velocity of the stack gas to improve air quality. The company has failed to solve the air problem and now has a noise problem.

STOPS 2 AND 3. Storm King-Cornwall Project
Storm King-Cornwall - Consolidated Edison Company of New York. Inc. - Pumped Storage - 2000 MW Proposed 1965. Planned Operation 1988
History
The ten-year legal battle between the Scenic Hudson Preservation Conference and Consolidated Edison Company of New York. Inc. over the Storm King project anticipated the environmental litigation that developed in the late 1960s and early 1970s, resulting in NEPA and subsequent Federal and State legislation governing air and water quality. It also highlighted a new area in the legal practice -- environmental law. The turning point in the Storm King case came in late 1965 when the United States Court of Appeals for the Second Circuit ordered the FPC to reopen proceedings after granting Consolidated Edison a license to build. The FPC was instructed to weigh aesthetic and other environmental values in the utility's proposal and to explore alternative means for meeting the project's objectives. In 1966 Consolidated Edison amended its plans to put the powerhouse entirely underground, thus eliminating the cut in the face of Storm King Mountain, and making the trail race less visible. Since licensing hearings before the FPC have been suspended until after October 1, 1976, it is not possible to accurately predict what constraints may arise from these hearings. Constraints could include possible reduction of biological impact of the plant. This may require fish protection devices or other mitigating measures, and continuation of present environmental studies or the addition of new studies to determine plant impact on aquatic population may be required.
In March 1976, at the request of the New York State Public Service Commission, Consolidated Edison submitted a report of a restudy of the need for, and economic justification of, the Cornwall project. The report says the underground pumped storage plant's capital cost would be about $1 billion and alternatives to the project would require an investment of $1.4 billion to $3.2 billion.
Engineering Geology
The Pagenstecher Creek fault lies to the northwest, separating the Highland's granite from sedimentary rocks to the north. This fault strikes northeast-southwest and dips steeply to the southeast. The surface and the Pagenstecher fault intersect at a minimum distance of 8,000 feet from the reservoir site; and the fault dips beneath the reservoir at depths between 6,000 feet and 29,OOO feet. The claim was made that the Pagenstecher Creek fault might be reactivated by the weight of the water as it rises and falls in the reservoir. The FPC found that the thousands of feet of sound, tight, granite rock and gneisses underlying the project are capable of sustaining any loading without movement of the Pagenstecher Creek fault.
The hazards to the Catskill Aqueduct from powerhouse excavation and vibrations caused by blasting were raised by New York City and Scenic Hudson. Construction of the powerhouse would require removal of approximately 254,000 cubic yards of rock. After several geologic studies and witnesses were heard on the subject of rock stress, the FPC concluded that the evidence in the record indicates that the probability of damage to the Catskill Aqueduct is remote.
2013: Update - 1980 (December 20) – Scenic Hudson and Consolidated Edison reached a settlement in which Consolidated Edison agreed to terminate its plans for Storm King Mountain, reduce fish kills at Indian Point and other power plants along the Hudson River, and establish a research fund for the Hudson River ecosystem in return for not having to install closed-cycle cooling towers at existing plants.

STOP 4. Ramapo Fault System, Stony Point, New York
The Ramapo Fault System, shown in Figure 7, extends for more than 50 miles northeast from Peapack, New Jersey to the Hudson River at Stony Point, New York just west of Indian Point. Along this trend, to at least the New York State border, the Ramapo Fault System is a zone in the Newark Basin. The term Ramapo Fault has been applied to the structure north of the New York State line where the fault system continues northeastward, but is divided into several major splays trending subparallel to each other and passing into the Precambrian Hudson Highlands on both sides of the Hudson River.

STOP 5. Indian Point, Buchanan, New York
Nuclear Unit 1 - Operational 1962, 260 MW (the second commercial reactor in the United States) -Shutdown in 1974 due to inadequate emergency core cooling system.
Nuclear Unit 2 - Operational 1976, 873 MW, has applied for its full operational license. Owned by Consolidated Edison Company of New York, Inc.
Nuclear Unit 3 -Operational 1978, 965 MW, has applied for its testing operational license. Owned by PASNY.
Seismic Analysis
The hearings on seismic safety of Indian Point have been held before the Atomic Safety and Licensing Board. The New York State Atomic Energy Council, Citizens Committee for the Protection of the Environment, Consolidated Edison, and NRC were parties in the proceeding. The following issues are in controversy:
(1) Does the Cape Ann earthquake of 1975, or any other historic event, require the assumption, in accordance with 10 CFR, Part 100, Appendix A, of a Safe Shutdown Earthquake for the Indian Point site greater than a Modified Mercalli Intensity VII?
(2) Should the ground acceleration value used for the design of Indian Point Unit 1, 2 or 3 be increased?
(3) Is the Ramapo Fault a capable fault within the meaning of Appendix A, 10 CFR, Part 100?
These hearings were completed this summer and decisions on these issues are expected this fall. The decision could effect the seismic analysis used in siting all nuclear plants.
At present, Consolidated Edison is undertaking extensive geologic and seismic studies of the Ramapo Fault System.
Environmental Impact
The major fishkills at Indian Point plants in the winter of 1964-1965 served to high-light the potential impacts of power plants on aquatic life. These fishkills added controversy to the Storm King hearings and the requirement for cooling towers at many power plants to protect aquatic life. At present. Consolidated Edison is under orders from NRC, at the request of EPA, to install cooling towers at Unit 2 by 1979 and at Unit 3 by 1981. Consolidated Edison has requested a variance on the tower requirement. The people of Buchanan, New York and local officials have opposed cooling towers due to the noise, visual impact and impacts on salt drift. Consolidated Edison has requested time to prepare impact studies.

STOP 6. Quarry Site, Wappinger's Falls, New York
Proposed Coal Plant - 700 MW - Power Authority of the State of New York
The quarry site is an alternative to the Arthur Kill site on Staten Island, New York. The plant would supply for the MTA. This would relieve some of the load carried by Consolidated Edison. This site is subject of an as-yet-to-be docketed Article VIII application pending before the New York State Public Service Commission.
Engineering Geology
This site is located next to one of the largest limestone aggregate quarries in the United States. On June 7, 1974 an earthquake of magnitude 3.3 occurred at the quarry site. All available evidence indicates that this earthquake sequence, and possibly past earthquakes in the same area, may have been triggered by crustal unloading associated with quarrying operations in the presence of high horizontal stress.
Environmental Geology
The coal plant proposed to be built will have SO2 stack gas scrubbing equipment. The only type of SO2 scrubbing equipment the engineers consider reliable enough to meet present air quality standards is a nonregenerable scrubber system, would produce over one million tons of toothpaste-like material requiring stabilization and disposal. The disposal options are quarries, the ocean or the Bahamas. The economic and environmental impacts of each option have yet to be fully explored.

C6: WALKING TOUR OF HISTORIC FISHKILL, NEW YORK
Harvey K. Flad
Department of Geology & Geography
Vassar College
The village of Fishkill was the scene of a number of important events during the Revolutionary War, and remained a serene rural village until the recent suburban growth of southern Dutchess County. Settled by the Dutch a few years after the granting of the Rombout Patent of 1685, Fishkill soon became an important center of local agricultural activities.
Participants of the walking tour will have a chance to enjoy the human scale of heritage that remains in historic Fishkill.

C6: WALKING TOUR OF HISTORIC FISHKILL, NEW YORK

Vassar Farm
On right is Vassar Farm, a 541 acre "island" of open space in the rapidly developing area. A concept master plan by Sasaki Associates, 1975, is presently underway to create a conservation area of over 300 acres.

IBM Development laboratories
IBM Development laboratories on the former Boardman-Kenyon farm.

View the Catskill Mountains
From this height one can view the Catskill Mountains across the Hudson River to the west. As one proceeds west on Spackenkill, note the development of single family dwellings on the left known as Hagantown. Vassar Farm property on right.

Spackenkill High School on left.
A confusion of architectural styles of the single family dwellings is evident (for example the peculiar "mansard" roof lines), as well as a lack of concern for appropriate front yard plantings along a busy highway. "For Sale" signs indicate continued growth.

Oakwood School on left.
This school is the oldest private coeducational boarding school in the United States, begun by Quakers in 1796.

South Road plant of IBM
As you cross the bridge ahead is the South Road plant of IBM, where much of IBM's hardware is constructed. IBM is the largest single private employer in Dutchess County. The summer home of Samuel F B.Morse. inventor of the telegraph, is just to the north of this plant.

I.B.M. Country Club on left, followed by Hudson Valley Block aggregate.

On right, low cost modular homes.

Poughkeepsie Asphalt. Inc
Poughkeepsie Asphalt. Inc. (bituminous concrete) on right.
2013: Good image of plant when it was operating, is on Google Earth, 2004.

Lone Star Industries - crushed stone
Lone Star Industries, New York Trap Rock Corporation Clinton Point Plant; Dutchess Quarry and Supply, on right. Major source of crushed stone (dolomite) (see: River Guide); also mentioned as potential site for nuclear power plant, although small earthquakes have been noted here.

George Clinton estate
Entrance to estate owned and occupied 1804-1812 by George Clinton, then vice president of the United States. No longer existing; owned by Lone Star Industries.

Mt. Alvernia seminary of the Franciscan Friars on the right.

STOP 1. View south.
View of Fishkill plains nestled at foot of Highlands; a strategic staging and transport center for the Continental troops.

Dutchess County Park on right.
Recently purchased by the county from Children's Aid Society in New York City, it was known as the Bowdoin-Vanderbilt Camp. During the past year geography students from Vassar College, landscape architecture students from Cornell, and ecology students from S.U.N.Y. Purchase studied the environment and social uses and created plans for the consideration of the county legislature. The work was coordinated by the Dutchess County Cooperative Association and County Planning.

Cross bridge over Wappinger's Creek.
On right is Wappingers Creek estuary; across railroad tracks and Hudson River see Danskammer power plant. The mouth of Wappinger's Creek was an important loading dock for produce from the farms of Dutchess County during the period just before the Revolutionary War. Dutchess County supplied much of the wheat for the Continental army.

STOP 2. Wappingers Falls
Walk from cars to bridge on E. Main Street over looking Wappingers Falls. The falls was a major source of power for textile dying firms (the bleachery); the village retains many fine nineteenth century facades.

Mesier Park.
Turn left into parking area at sign for police station. Mesier Homestead, c.1750. Peter Mesier, a New York City merchant, bought the grist mills originally built by the Brewer brothers in 1777. Because Mesier held Tory sympathies, his store (operated from part of this house) became the scene of several "Wappingers Tea Parties" where Whigs and patriots broke into Mesier's house and store and "protested" his price of tea by "consuming large quantities of liquor."

The Dutch Reformed Church
The Dutch Reformed Church was originally built in 1731 although it was substantially rebuilt in 1786 after its active use during the Revolutionary War. During the Revolutionary War it served as the seat of the Provincial Congress from September 1776 to February 1777, after it had fled from New York City and White Plains, making Fishkill the capital of New York for that period. Later in the war the church was used as a military prison and was the scene of the "escape" of Enoch Crosby, patriot spy, which became the basis for John Fenimore Cooper's novel The Spy.

Trinity Church
Trinity Church, built in 1768, is the county's oldest church building still in use. During the Revolutionary War it was first used for a meeting of the Provincial Congress; later it became a military hospital.

STOP 3. Assemble for "Walking Tour of Historic Fishkill"
(approximately 1.5 hours). Of the many interesting buildings, two are of greatest interest: the First (Dutch) Reformed Church and Trinity Church.

STOP 4. Van Wyck-Wharton House
Van Wyck-Wharton House, at Interstate 84 and Route 9, was built in 1733, with a major addition twenty years later. During the Revolutionary war the house was used by the Continental army and quartermaster department officers stationed at the Fishkill camps, and was also the scene of several courts martial. Built by the Van Wycks, it has also had the name Wharton attached to it as it was the inspiration for the Wharton House in James Fenimore Cooper's novel The Spy.

C7: STRATIGRAPHY AND STRUCTURAL GEOLOGY IN THE HARLEM VALLEY, S.E. DUTCHESS COUNTY, NEW YORK*
James M. McLelland
Colgate University
Donald W. Fisher
New York Geological Survey
The purpose of this field trip is to provide familiarity with the stratigraphy and structure of the Amenia-Pawling portion of the Harlem Valley in eastern New York State. Emphasis is placed upon stratigraphic relations of the Wappinger Group (Dana, 1879) which represent the Cambrian-Ordovician carbonate shelf sequence in this portion of the Appalachians. Additional stops will be made to examine the Poughquag Quartzite, the Walloomsac Schist, the Everett Schist, and Precambrian units of the Hudson Highlands, all of which are integrally related to the regional geology.
It should be understood that the structural framework and geologic history of this area have not been clearly deciphered. As in other parts of the Taconide Zone (Zen, 1972), complex polyphase deformation, regional metamorphism, and limited exposure have combined to leave scanty evidence of a protracted geologic history. A great deal more detailed work is required before the Harlem Valley area is well understood. It is our hope that this trip may arouse sufficient interest in the regional geology so that others will decide to undertake further field studies in the area.
Acknowledgments
We thank the following individuals for their roles in enhancing our understanding and interest in the local geology: John Rodgers, Yngvar Isachsen, and Rosemary Vidale. One of us (JMM) was supported by a NSF Science Faculty Fellowship during the summer of 1971.
* In large part reprinted from NEIGC Guidebook, 67th Annual Meeting, 1975, with permission of editors.
Summary
Although important unresolved problems remain in the Amenia-Pawling Valley, we are able to conclude with reasonable certainty that the valley is underlain by the overturned, eastern limb of a large NNE trending syncline. In the western limb of this fold the carbonate shelf remains hidden beneath Walloomsac and Everett schists. This structure is termed the Harlem Valley Syncline and is thought to be complementary to the Housatonic Highland massif and its southern extension. It is suggested that the Proterozoic gneisses at Corbin Hill are a relict klippen of a hard-rock thrust slice emplaced in the late Taconian Orogeny (Hudson Valley phase). Local allochthons of Everett Schist were emplaced at the sane time. Penetrative cleavage and metamorphism followed these events, probably, in late Ordovician time. A Devonian overprinting of Ordovician metamorphism is probable.

C7: STRATIGRAPHY AND STRUCTURAL GEOLOGY IN THE HARLEM VALLEY, S.E. DUTCHESS COUNTY, NEW YORK
James M. McLelland
Colgate University
Donald W. Fisher
New York Geological Survey
The purpose of this field trip is to provide familiarity with the stratigraphy and structure of the Amenia-Pawling portion of the Harlem Valley in eastern New York State. Emphasis is placed upon stratigraphic relations of the Wappinger Group (Dana, 1879) which represent the Cambrian-Ordovician carbonate shelf sequence in this portion of the Appalachians. Additional stops will be made to examine the Poughquag Quartzite, the Walloomsac Schist, the Everett Schist, and Precambrian units of the Hudson Highlands, all of which are integrally related to the regional geology.
It should be understood that the structural framework and geologic history of this area have not been clearly deciphered. As in other parts of the Taconide Zone (Zen, 1972), complex polyphase deformation, regional metamorphism, and limited exposure have combined to leave scanty evidence of a protracted geologic history. A great deal more detailed work is required before the Harlem Valley area is well understood. It is our hope that this trip may arouse sufficient interest in the regional geology so that others will decide to undertake further field studies in the area.
Acknowledgments
We thank the following individuals for their roles in enhancing our understanding and interest in the local geology: John Rodgers, Yngvar Isachsen, and Rosemary Vidale. One of us (JMM) was supported by a NSF Science Faculty Fellowship during the summer of 1971.
* In large part reprinted from NEIGC Guidebook, 67th Annual Meeting, 1975, with permission of editors.
Summary
Although important unresolved problems remain in the Amenia-Pawling Valley, we are able to conclude with reasonable certainty that the valley is underlain by the overturned, eastern limb of a large NNE trending syncline. In the western limb of this fold the carbonate shelf remains hidden beneath Walloomsac and Everett schists. This structure is termed the Harlem Valley Syncline and is thought to be complementary to the Housatonic Highland massif and its southern extension. It is suggested that the Proterozoic gneisses at Corbin Hill are a relict klippen of a hard-rock thrust slice emplaced in the late Taconian Orogeny (Hudson Valley phase). Local allochthons of Everett Schist were emplaced at the sane time. Penetrative cleavage and metamorphism followed these events, probably, in late Ordovician time. A Devonian overprinting of Ordovician metamorphism is probable.

STOP 1. Roadcuts in Walloomsac and Wappinger
Roadcuts in Walloomsac schist and Wappinger carbonates on both sides of NY 22.
Here the Walloomsac schist overlies calcitic and dolomitic limestones of the upper Wappinger -- possibly the Copake Limestone. The presence of brown and tan weathering dolostone beds in the carbonates preclude their being Balmville. Probably this was a site of non-deposition of the Balmville. At or near the contact, there is developed tectonic interleaving of schist and carbonate. This interleaving could result from at least two causes: (1) differing mechanical properties of the schists relative to the carbonates; (2) the shearing off of original irregularities along the old erosional surface. Within the outcrop, the foliation and bedding surfaces strike N40E and dip 50°W. The stratigraphy is right side up. Tight folding takes place about N10-15E axes and the folds verge westward. Near the south end of the outcrop there exist good examples of the relationship of fold wavelength to bed thickness. Note that the principle foliation has been refolded representing, probably, the D2 and D3 events. A thin section of Walloomsac from this outcrop shows abundant quartz and biotite as well as garnet, feldspar, muscovite, graphite, and metallic opaques. Two generations of biotite can be seen megascopically.

STOP 2. Large roadcuts in upper Wappinger carbonates.
Nellie Hill. The beds strike N10-20E and dip 30°-40°E. In the fields beyond the west side of the road are outcrops of Balmville Limestone and Walloomsac Schist that also dip to the east. If one proceeds eastward over the top of the roadcut and onto the next ridge (-300 m), Briarcliff Dolostone is encountered. Still further to the east the Pine Plains Formation, Stissing Dolostone, and Poughquag Quartzite crop out successively until the proterozoic gneisses of the Housatonic Highlands rise in the ridge defining East Mt. Except for minor folding, the strata dip consistently to the east and the entire section must be regarded as overturned. Chestnut Ridge, immediately to the west on Rt. 22, consists of Everett Schist and is regarded as an allochthonous hard-rock slice.
The southern portion of the outcrop is thought to consist of Copake Limestone that has been pervasively folded about N10-20E axes, plunging l0°-l5°N. Excellent examples of transposed bedding and thinned out fold limbs can be seen. The rock consists of dark, pure calcitic metacarbonate interbedded with coarser sandy dolostone. Possible crossbedding can be seen in the steep walls of the roadcut.
At its northern end, the outcrop shows the development of well layered buff and brown dolostone beds interlayered with dark, massive calcite rich beds. These units are thought to belong to the upper portion of the Rochdale Limestone. Bedding averages around 0.5-1 m in thickness. Some of the dolostone beds are quartzose and show thin bedding laminations. No cross-bedding or graded bedding has been recognized and discoveries of the same will be welcomed.
Above the road level, and within the tree cover, there are developed coarse, gray, massive limestones that extend to the top of the hill. These are considered to be part of the Rochdale. Between the hilltop and the Briarcliff dolostone, limestone bearing units of possible Halcyon Lake assignation crop out. A problem with the correlations as given above is that the resulting thickness of the Rochdale Limestone is less than would be expected. Warthin (pers. comm.) reports approximately 125 m of Rochdale near Poughkeepsie. If the Halcyon Lake is present in the section above the Briarcliff here, it does not appear possible to have 125 m of Rochdale. Perhaps faulting has cut out some of the section. Alternatively the Halcyon Lake Fm. may not have been deposited locally. A further possibility is that the beds assigned here to the upper Briarcliff are actually Halcyon Lake.

STOP 3. Excellent outcrops of Everett Schist
Park on east side of NY 22 near bend in road. Walk southward along railroad tracks, for approximately 150 meters. Excellent outcrops of Everett Schist are exposed in a small railroad cut. NO HAMMERS PLEASE. Large (1/8" -1/4") staurolite and garnet crystals are developed in coarsely micaceous muscovite schists which display the typical silver sheen of the Everett at this grade. Quartz and feldspar are plentiful with quartz predominating. Some graphite is present. The foliation has been refolded.

Briarcliff Dolostone on east side of road.

Briarcliff Dolostone on hill to west of road.

Briarcliff Dolostone in roadcut.

Abandoned quarry in Briarcliff Dolostone to south of road.

Cut in Briarcliff Dolostone.

Cut in Pine Plains Formation.

STOP 4. Peckham Industries Quarry
The quarry is within Stissing Dolostone and the broad expanse of dazzling white dolostone reflects the purity of this lowermost carbonate. During World War II, this quarry was utilized as a source for magnesium. Within most units the rock consists almost entirely of dolomite and calcite. The structure within the quarry seems to be fairly straightforward. Bedding dips steeply around an anticline that trends N10-20E and plunges 10°-15°S. The core of this anticline is preserved in the lower quarry level where pelitic beds of Stissing are also exposed. Presumably these are related to the red shale horizons recognizedby Mrs. Knopf (1946) near the middle of the Stissing. At the stratigraphic level of the pelite rich zones, the Stissing is difficult to distinguish from portions of the Pine Plains Formation.
At the south end of the quarry beds of Pine Plains dolostones overly the Stissing. The Pine Plains appears to overly the Stissing around the entire margin of the quarry, reflecting its overall anticlinal structure. Because its regional extent is unknown, the Pine Plains in this area has been mapped in Undivided Carbonates (Of) in fig. 2.
In terms of regional structure, note that the quarry lies within the Wingdale-Bulls Bridge gap. Within this gap the Stissing Dolostone appears to wrap around the southern end of the Housatonic Highlands. Moreover, Stissing within the gap appears to be structurally and stratigraphically continuous with Stissing to the west in the Harlem Valley. This strongly suggests that the gap represents the south plunging nose, and upper limb, of the westward verging anticlinorium cored by the Proterozoic gneisses of the Housatonic Highlands. The possibility exists that this anticlinorium is developed on an eastward dipping thrust plate (Harwood and Zeitz, 1974).

Pine Plains Formation on west side of Rt. 22

Pine Plains Formation on east side of Rt. 22.

Manhattan Formation
Manhattan Formation of the schist mass comprising the east side of the valley.

Pine Plains Formation on west side of Rt. 22.

Stissing Dolostone on both sides of Rt. 22.

STOP 5. Corbin Hill
The long roadcuts on either side of NY 22 are fine examples of Pine Plains Formation. However we will not examine these at this location. The primary purpose of this stop is to point out, and discuss Corbin Hill which rises from the swampy fields to the west of NY 22.
Corbin Hill consists of Proterozoic (Helikian) gneisses whose bedding and foliation are conformable to the valley trends. These gneisses are surrounded by, and may rest on top of, interlayered Balmville limestones and Walloomsac slates. Balk, 1936, considered Corbin Hill to represent a slice of basement brought to its present erosional level along a steeply dipping reverse fault block that involved Precambrian rocks only (fig. 5a). If this mechanism is correct, then it should be reflected by a break in the stratigraphic succession of the valley carbonates. Similarly, if Corbin Hill punched its way upward as an elongate domal mass, then the carbonate stratigraphy should wrap around the Precambrian gneisses (fig. 5c).
Mapping around Corbin Hill has shown that the carbonate stratigraphy is unaffected by the gneiss body. Units of the Wappinger Group can be followed down the valley and "through" Corbin Hill with no signs of displacement or "wrapping-around". As shown in fig. 2, the Briarcliff Dolostone is the Wappinger unit underlying Corbin Hill. This is inconsistent with an up punched or up thrust origin of this feature. Similarly the presence of Balmville limestone, Walloomsac Schist, and even Everett Schist in close proximity to the western margin of the Precambrian gneisses makes it difficult to account for Corbin Hill by essentially autochthonous mechanisms. The stratigraphic continuity of the carbonate shelf units, and their overturned attitudes, cannot tolerate vertical movement models for Corbin Hill. In effect, the gneisses on Corbin Hill do not appear to be rooted through the valley carbonates. While this conclusion cannot be made firm without further evidence it does represent our preferred interpretation of the field data.
In the absence of further data, we are unable to offer any convincing, detailed history relating to the origin of Corbin Hill. Our preferred model is that these gneisses represent an erosional outlier of a low dipping hard-rock slice that transported Proterozoic rocks from east to west. Rather than suppose the existence of extensive Proterozoic rocks in this slice (fig. 5d), we prefer to attribute the rocks of Corbin Hill to tectonic slivering of basement rock by an overriding slice of Everett Schist (fig. 5e). This slivering could have occurred in the basement rocks that underly the Manhattan Schist terrain, forming the ridge on the east side of the valley. While other source areas exist, this one appears to be the most economical of long distance transport. Similarly, slivering of the Proterozoic offers the simplest explanation for the restricted outcrop of Corbin Hill.
The foregoing model is consistent with the recent aeromagnetic interpretations of Harwood and Zeitz (1974) for rocks of the Housatonic massif. Here, eastern, weakly magnetic Precambrian rocks are thrust westward along low angle faults rooting in the east. This thrusting occurred late in the Taconian Orogeny and involved the various hard-rock slices of the High Taconics and the Precambrian massifs. Note that just to the north of Towners, New York, Balk (1936) mapped Precambrian and Poughquag Quartzite thrust over carbonate units. Lying north of this is the small Pine Island mass of Precambrian and Poughquag which, presumably, is also thrust in (see STOP 9).

Pine Plains Formation on east side of NY 22.

Briarcliff Dolostone on east side of NY 22.

Briarcliff Dolostone in large roadcut on east side of NY 22.
Abundant diopside and tremolite are developed in the outcrop.

Briarcliff Dolostone on west side of NY 22.

STOP 6. Road cut in the Pine Plains Formation.
Excellent example of the highly variable lithologies that characterize this unit. Brown and buff sandy dolostones alternate with quartzites and relatively pure, massive white dolostones. Tan colored units often shows typical rotten weathering. Punky, asphalt bearing layers give off H2S upon breaking open. Bedding is of variable thickness. The beds of quartzite and chert have undergone boudinage and pinch and swell of textbook quality. Reaction rims and selvages exist between the carbonates and the quartz rich layers. In the brown to purplish pelitic zones phlogopite, sphene, diopsidic pyroxene, and tremolite are developed. Within the more massive beds of grey weathering, white colored dolostones diopside tablets attain dimensions approaching 3 cm across.
On the east side of NY 22, the Pine Plains units strike subparallel to the road and dip steeply to the east. On the west side the strike has turned E-W and dips are steeply to the south. This represents a fairly open, dextral type of fold that swings the carbonate units and the Manhattan Schist westward for about 0.8 km at which point strikes return to NNE trends (see fig. 3).
The contact between the Briarcliff dolostones and the Pine Plains Formation is thought to occur just to the west of NY 22. The low hill rising from NY 22 is known to be underlain by Briarcliff Dolostone and this unit is beautifully developed just to the south of the NY 55 underpass (0.5 km along strike to the north). Perhaps some of the massive, pure dolostone at the north end of the cut should be assigned to the Briarcliff.
Minor folds in the outcrop suggest that we may be observing here the limbs of larger isoclinal folds. Two foliations exist and are best manifested by micaceous bands.

Briarcliff Dolostone
Briarcliff Dolostone with excellent diopside crystals on north side of NY 55.

STOP 7. Very large roadcuts in the Briarcliff Dolostone.
The Briarcliff consists typically of grey weathering, light colored rather pure dolostones with yellow to white and even black chert layers (1"-2") abundantly developed in some units. Knots and nodules of vitreous quartz are locally present and weather out above the dolostone surface. At the east end of the cut some dirty portions of the Briarcliff exhibit moderate development of phlogopite. At the western end of the beds of dolostone are massive and pure. This difference appears to be reflected in the more open style of folding associated with the pure thick layered (5-7 m) beds.
A large number of different structural styles and phenomena can be seen in the roadcut. Folds range from fairly open flexural styles to isoclinal folds that may involve flowage and/or significant flattening. In many areas of the cut disharmonic folding is pronounced with the dolostones undergoing extensive flowage while the much more brittle chert layers show rupturing and extensive separation of blocks. Examples of the folded boudinage are beautifully developed at the eastern end of the roadcut.
There appear to be at least four major compressional events recorded in the outcrop. The earliest of these is manifested by only an early foliation (flakes of phlogopite) that lies within the surfaces rotated by the earliest recognizable folds. These folds are generally very tight to isoclinal and their axial planes display a variable attitude. In general the axes of these folds do not plunge steeply but exceptions are common due to later refolding. These tight folds are then refolded about NNE axes with relatively steep plunges (50-60°). This leads to an interesting set of geometrical relationships wherein the early isoclinal folds are well exposed in vertical faces of the cut while the steeply plunging folds are best seen on horizontal erosional surfaces. A final set of upright, open, and gently plunging folds that trend approximately N-S. These are best exposed near either end of the large road cut.
Fold interference patterns are best seen at three places. The first is on the north side of the road and near the east end of the roadcut just prior to the beginning of the cut is really steep faces. Here upright isoclinal folds are clearly refolded by steeply plunging, tight folds. Close examination of the folded surfaces of the isoclinal folds indicates phlogopite mica growing parallel to them. Folded boudinage also appears to be present.
A second vantage point for observing fold interference is on the north side of the cut just beyond the large saddle nearly 2/3 of the way up the cut. Here several pelitic layers define the core region of early gently plunging isoclinal folds. These can be clearly seen to be folded by a later, steeply plunging fold set.
A third example of fold interference lies on the south side of the cut almost directly opposite the case cited immediately above.
Numerous high angle faults cause observable offsets in the dolostones. Some of the fault stones contain serpentine. These faults appear related to a larger fault zone that causes a topographic saddle about half way along the roadcut.
Of particular petrologic interest are layers of tremolite and diopside in the Briarcliff. These are best observed on the top of the roadcut at its southeastern end. Massive beds of tremolite and diopside areas are mutually exclusive and seem to reflect the relative immobility of the vapor phase during metamorphism. Note that the diopsides, especially, appear to post-date any severe orogenic events.

Calcitic Walloomsac schists
Calcitic Walloomsac schists containing calc-silicates, calcite, and overlain by a calc-silicate bearing calcitic dolostone. The latter may be a tectonic sliver similar to those seen at Stop 1.

STOP 8. Balmville / Walloomsac contact
In this small roadcut we are afforded a view of the contact between the Balmville Limestone and the Walloomsac Schists. At the north end of the outcrop the schists overly the Balmville, but at the south end, units dip steeply to the east, and, if outcrop were preserved, the Balmville would overly the schists. We consider this relationship to be due to proximity to the hinge line of the overturned Harlem Valley Syncline whose upright, western limb is entered as NY 55 is followed to the west (see fig. 3). The roadcut itself probably represents a minor fold near the hinge line since black Walloomsac calcitic schists are found farther to the east at mileage 26.8.

STOP 9. Thrust contact
Thrust contact between the Proterozoic gneiss and the Cambrian-Ordovician shelf sequence. Balk (1936) mapped the Towners Thrust through this area. As he indicated, the upper thrust plate consists of Proterozoic gneisses overlying Poughquag quartzites. Beneath the Poughquag there appears a much deformed and cleaved impure dolostone. Because of the impurity of this unit (particularly the number of chert stringers in it), we have tentatively correlated these dolostones with the Briarcliff. The possibility remains that future work will result in a revision of this correlation and the dolostones may be incorporated into a dirty, lower facies of the Stissing. At this grade of metamorphism, and with lack of fossil control, it is difficult to make stratigraphic assignments with absolute certainty. However, the present correlation is preferred.
If the dolostones at this stop are accepted as Briarcliff, then the stratigraphy itself necessitates a reverse fault between the Proterozoic/Poughquag and the underlying Briarcliff. Such stratigraphic control would demonstrate thrusting, and fix its minimum displacement. However, this control is not necessary in order to demonstrate that low angle faulting was extremely likely in this area. Balk (1936) concluded that fabrics and minor structures in the surrounding rocks strongly suggested a reverse fault at the Proterozoic/Poughquag contact with the carbonates. Examination of the Proterozoic gneisses shows the presence of strong mineral lineations, rodding, and grooving near their lower contact. An anastomosing network of foliation planes can be seen intersecting an earlier foliation. The later foliation is oriented approximately parallel to the postulated plane of faulting and is believed to be similar to the mylonites observed by Ratcliffe (1975) and Harwood (1975) in thrust slices of the Berkshire massif. The linear features developed on these foliation planes are thought to manifest the slip direction along the fault. Pronounced grooving in the Poughquag quartzite is attributed to the same tectonic event. These lineations trend E-W and plunge to the east at about 40°. Within most of the Harlem Valley lineations vary around NNE and NNW directions parallel to the major fold axes. The high angle between the lineations here and both regional and local fold axes strongly suggests that the linear features are a result of fault motion and probably lie parallel to the slip vectors along these faults (i.e. an "a" lineation).
At the Proterozoic-Poughquag contact there are developed biotite rich seams that resemble the blastomylonites of the Berkshires (Ratcliffe, 1975; Harwood, 1975).
A short distance up the hillside to the southeast there is exposed a vertical face of Proterozoic granitic gneiss. The foliation in this rock has been tightly refolded about gently dipping axial planes, many of which have been infilled by quartzo-feldspathic material. These axial planes dip parallel to the presumed thrust fault. The lower limb of several of the folds have been attenuated. A general East over West movement is indicated. As with the linear features and mylonites, these folds and granitic seams are reminiscent of minor structures of the Berkshires. We believe that the minor folding and associated axial plane foliation in these rocks are the consequence of westward thrusting of the Proterozoic, with local patches of attached Poughquag quartzite, over the Cambrian-Ordovician carbonates.
As shown on fig. 6 the Towners Thrust extends well beyond its exposure at Stop 10. Following Balk (1936), we conclude that it is likely that Pine Island is part of the thrust plate and this hypothesis has been incorporated into fig. 6. The eastern margin of the thrust plate cannot be drawn in with any certainty, and we have not attempted to extrapolate beyond Pine Island.
The full extent of the Towners Thrust is presently unknown. It may continue southward into the pronounced N-S valley within the Proterozoic. In this case the small outcrops of Wappinger carbonates in this valley may represent tectonic slivers along the sole of the thrust. Alternatively the trace of the thrust may pass along the Proterozoic-Paleozoic contact west of Towners (fig. 6), and then swing to the south at the western margin of this Proterozoic block. This is essentially the pattern shown on the 1973 edition of the New York State Geological map. Such a trace would explain the abrupt truncation of the carbonate shelf sequence by the Proterozoic just to the west of Towners. It would also explain the fact that, along its western contact, this mass of Proterozoic appears to overly shelf carbonates. A third possibility is that the abrupt termination of the Paleozoic stratigraphy west of Towners is due to a WNW high angle fault that connects the thrust at Cornwall Hill with its continuation along the N-S Proterozoic-Paleozoic contact west of Towners. In this case the small carbonate bodies referred to above as possible tectonic slivers might possibly lie within erosional windows through the overlying Proterozoic thrust sheet.
The regional extrapolation of the Towners Thrust remains a major research problem in the area. Together with Corbin Hill, it raises the possibility that portions of the Hudson Highlands may be parautochthonous, as in the Berkshires, or even allochthonous, as suggested by Isachsen (1964).