NYSGA 1987
NEW YORK STATE GEOLOGICAL ASSOCIATION
59TH ANNUAL MEETING
NOVEMBER 6-8, 1987
FIELD TRIP GUIDEBOOK
EDITOR
RUSSELL H. WAINES
DEPARTMENT OF GEOLOGICAL SCIENCES
STATE UNIVERSITY OF NEW YORK
COLLEGE AT NEW PALTZ
ACKNOWLEDGEMENTS
In rereading the letter of acknowledgements for the 39th Annual New York State Geological Association Guidebook I find little has changed except for the names of most of the participants.
Again I thank the contributors named in the page of contents. Their considerable efforts have provided the 'meat' of the present Guidebook, not only for the moment in this year's trips, but for the anticipated use extending many years into the third millennium.
Additionally, many have labored mightily in other ways to make this year's meeting a success; Diana Parrett, Constantine Manos, Rosario Agostaro and, in many special ways, Robert Cunningham. All of these in one way or another are associated with the Department of Geological Sciences at SUNY, New Paltz and each deserves a special thanks. Many others have given timely assistance; the classes of oceanography and sedimentary petrology at SUNY New Paltz as well as many members of the New Paltz Geological Society who helped with registration, as road guards, and other vital activities and without whose help the work of others would have been much more onerous. Three others at some point in time in this effort have helped in timely fashion; John Johnsen of Vassar College, my wife Dorothy Waines and Martin Rutstein of our Department. Their help is very much appreciated.
Finally, I must mention and thank Todd Leeds of our Department whose excellent oblique aerial photo of the Sky Top Tower at Mohonk Lake graces the Guidebook cover. I should mention also that the tower sits on a fine exposure of a Late Silurian oligomictic orthoconglomerate.
As I wrote twenty years ago "to all these and more, the Guidebook and Annual Meeting owe whatever approbation is deserved."
Russell H. Waines,
Editor

A: PAC STRATIGRAPHY OF THE BINNEWATER, RONDOUT AND MANLIUS FORMATIONS OF THE HUDSON VALLEY
E.J.Anderson, P.W.Goodwin, T.R.Buggey, S.P.Osborn, L.J.Saraka and W.M.Goodman TEMPLE UNIVERSITY
INTRODUCTION
The purpose of this trip is to present a demonstration of field application of the PAC hypothesis. Specific objectives include:
1. demonstration of criteria for recognition of PACs in a variety of facies (all STOPS);
2. field checking of stratigraphic columns described in terms of PACs (all STOPS);
3. illustration and discussion of methods of correlation of PACs (all STOPS);
4. demonstration of a major cryptic unconformity at the Manlius-Coeymans boundary (STOPS 1, 2, 3 and 6);
5. demonstration of a minor cryptic unconformity at the PAC 3-5 boundary (STOPS 1, 4 and 6);
6. demonstration of lateral facies change within a PAC (e.g. PAC 9, STOPS 1, 2, 3 and 6);
7. demonstration of episodic onlap over the Ordovician land surface (STOPS 1, 4, 5 AND 6).
THE PAC HYPOTHESIS
The PAC hypothesis (Goodwin and Anderson, 1985) is a comprehensive stratigraphic model which states that most stratigraphic accumulation occurs episodically as thin (less than 5 meters thick), generally shallowing-upward cycles characterized by internal vertical and lateral facies continuity (i.e. conjunct facies relationships). Cycle boundaries, defined by abrupt facies change to disjunct facies, are created by what stratigraphically appear to be geologically instantaneous relative base-level rises. The PAC motif (punctuation and aggradation) is independent of specific facies and therefore a single PAC may be peritidal at one locality and totally subtidal at another locality. The events which produce PAC boundaries are thought to be sea-level fluctuations. Because such events are allogenic, PAC boundaries are essentially synchronous surfaces. PACs are therefore ideal stratigraphic units for intrabasinal correlation and paleogeographic reconstruction.
STRATIGRAPHY OF THE LOWER HELDERBERG GROUP IN THE HUDSON VALLEY
The Binnewater, Rondout and Manlius Formations between Wilbur and Catskill, New York are totally divisible into PACs which can be correlated throughout the study area. The general stratigraphic relationships of these formations and their members were carefully documented by Rickard (1962). Paleoenvironmental interpretations of these rocks were presented by Waines (1976), Harper (1969) and Laporte (1967 and 1969) . An episodic (PAC) stratigraphic interpretation of the formal rock unit boundaries in this area was presented by Anderson, Goodwin and Sobieski (1984) and the cyclic facies architecture and its implications were presented by Osborn (1983), Buggey (1984), Saraka (1984), Goodman (1985) and Goodwin et al. (1986).
In brief summary, the rocks in the study interval represent a diverse set of peritidal and shallow subtidal facies deposited in small-scale allogenic cycles. Correlation and analysis of the distribution of these cycles leads to recognition of a pervasive structure of discontinuities in the lower Helderberg Group. There are not only sedimentologic discontinuities at the bed level but several types of stratigraphic discontinuities (PAC boundaries, small and large scale cryptic unconformities and a traditional angular unconformity).

STOP 1. North Catskill Route 23 exit ramp
.3 miles southwest of New York State Thruway Exit 21.
The Rondout, Manlius, Coeymans and Kalkberg Formations are continuously exposed above an angular unconformity with the Ordovician Normanskill turbidites. The Rondout Formation is made up of 1 PAC and the Manlius contains 10 PACs (PACS 5-14) at this locality. The Rondout PAC has a subtidal fauna in its base and is topped by a massive supratidal dolomite. The first Manlius PAC has been broken up by tectonism. It is overlain by a peritidal PAC (PAC 6) which is probably similar in facies to the tectonized unit. PACs 7, 8, 11, 13 and 14 are entirely subtidal and PACs 9, 10 and 12 are again peritidal cycles.
In addition to discussing criteria for PAC recognition we would like to focus attention on the following observations at this stop. 1. A major correlation point for Manlius PACs is the facies change from cryptalgal laminites to stromatoporoid bearing calcarenite at the base of PAC 11. We will trace this boundary throughout the study area. 2. The stromatoporoid bearing calcarenite at the base of PAC 9 is replaced laterally by thin-bedded shallow-water carbonate turbidites at Stop 2 and gastropod bearing calcisiltite in the Kingston area (Stops 3 and 6). 3. PAC correlations reveal that the Manlius/Coeymans formation boundary is a major cryptic unconformity. To the south at Kingston, PACs 13 and 14 are missing by erosion. To the north and west an additional PAC occurs beneath the unconformity. 4. A minor cryptic unconformity occurs at the boundary between PACs 3 and 5. South of Kingston, PAC 4 is found in this gap. 5. Finally, additional PACs appear below Rondout PAC 3 in the southern localities indicating progressive onlap of the Ordovician land surface.

STOP 2. South Catskill
Route 23A, .2 miles southwest of the intersection with Route 9W.
Manlius PACs 6 to 14 are exposed at this locality. The measured section, both overall and cycle by cycle, is nearly identical in thickness to the North Catskill section observed at the last stop. There are two purposes to this stop. 1. We will demonstrate, PAC by PAC, the degree of similarity between two localities two kilometers apart. This analysis is based on PAC correlations. Marked similarity between the two localities is seen in the thick tidal-flat facies in the upper part of PAC 9 and in PAC 10 and in the major facies change to stromatoporoid bearing calcarenite in PAC 11. In addition, the cryptalgal laminite facies with eroded mudcracks on its upper surface at the top of PAC 12 is the same as at North Catskill A-6 Another primary correlation point is the large facies change from peritidal to subtidal facies at the PAC 5-6 boundary. 2. The second purpose is to demonstrate lateral facies changes within PACs. The boundary between subtidal PACs 7 and 8 is more sharply defined than at the first locality because the calcarenite in PAC 7 is more current washed than at North Catskill. More dramatic lateral facies change within a PAC is illustrated in the base of PAC 9. At this level stromatoporoid bearing calcarenite at North Catskill changes to thin-bedded shallow-water carbonate turbidites.

STOP 3. KINGSTON A
Route 199, .5 miles west of the Kingston- Rhinecliff Bridge.
Manlius PACs 7 to 12 are exposed at this locality. In addition to checking PAC definitions, the following observations can be made at this stop. 1. The primary correlation datum is the major facies change to stromatoporoid bearing calcarenite at the base of PAC 11. Also, as at Catskill, a thin cryptalgal laminite facies occurs at the top of PAC 12. 2. If these correlations are correct, PACs 13 and 14 are missing under the first PAC of the Coeymans Formation indicating a progressive enlargement of the cryptic unconformity seen at Catskill. 3. A major lateral facies change has occurred in the PAC 9-10 interval. These PACs are here represented by subtidal gastropod bearing facies while at Catskill we saw two well developed peritidal cycles at this stratigraphic level.

STOP 4. KINGSTON B
Route 32, .5 miles south of Route 199.
The top of Rondout PAC 2, Rondout PAC 3 and Manlius PACs 5 and 6 are well exposed at this locality. The following observations can be made at this stop. 1. PACs 5 and 6 are peritidal cycles overlain by the subtidal calcarenite facies of PAC 7. This pattern supports the correlation with the like numbered units at Catskill. 2. As at Catskill, PAC 5 overlies the massive Whiteport Dolomite of PAC 3 (Fig. 4). Also, as at Catskill, PAC 4 is still missing in a minor cryptic unconformity (Fig. 2).

STOP 5. Kingston C
Route 32, .5 miles south of Stop 4.
Rondout PACS 2 and 3 (the upper part of PAC 3 covered here is fully exposed at the previous stop) overlie Ordovician turbidites of the Normanskill Formation in angular unconformity. PAC 2 is represented by the Wilbur and Rosendale Members of the Rondout Formation and PAC 3 by the Glasco and Whiteport Members (the PAC numbering system, data and interpretations in Figure 4 are taken directly from Osborn's 1983 thesis and differ slightly from those presented in the text of this paper and Figure 21. An increase in the number of Rondout PACs at Kingston relative to Catskill indicates progressive stepwise onlap to the north over the Ordovician land surface during Rondout time.

STOP 6. South Wilbur
Abandoned quarry above road along Rondout Creek, . 5 miles southwest of Wilbur, New York.
Exposed at this locality are two PACs of the Binnewater Sandstone taken from Buggey, (1984), four Rondout PACs and eight Manlius PACs. Several observations and interpretations can be made at this locality.
1. There is an excellent correlation of PACs in the Manlius interval with those observed at Kingston localities A and B. Key correlation points include the major facies change to calcarenite at the base of PAC 7, the thin-bedded gastropod bearing facies which characterizes PACs 9 and 10 and the major facies change to thick-bedded stromatoporoid bearing calcarenite at the base of PAC 11.
2. More erosion at the Manlius-Coeymans cryptic unconformity has reduced the thickness of PAC 12 to about 1 meter. Note the minor paleokarst developed on the unconformable surface. 3. PAC 4 appears between PACs 3 and 5. The presence of this PAC to the south and its absence to the north is evidence of a minor cryptic unconformity . In the initial study of this interval Osborn (1983) recognized the facies change which now defines the boundary at the base of PAC 4 but did not set it off as a PAC boundary because it was absent at the northern localities (Fig. 4). Osborn placed this unit in the upper 2-4 feet of the Whiteport Member of the Rondout Formation at the Fourth Lake, Wilbur and Connelly localities. Interpretation of a cryptic unconformity at this level provides an explanation for these facies patterns.
4. The two Binnewater PACs preserved at this locality were shown by Buggey (1984) to be correlated with two PACs in the middle of the Binnewater Formation ten miles to the south at High Falls. This correlation leads to the interpretation of the Binnewater/Rondout contact as a cryptic unconformity at which at least two PACs are lost at South Wilbur.
5. Finally the High Falls and Binnewater Formations progressively and episodically onlap the underlying Ordovician Normanskill Formation as does the Rondout Formation at Kingston and to the north.

B: PREGLACIAL AND POSTGLACIAL DRAINAGE OF THE CENTRAL HUDSON VALLEY
"Robert J. Dineen
New York State Geological Survey
Room 3160, Cultural Education Center
Albany, New York 12230
INTRODUCTION
The Problem
The preglacial drainage patterns of the mid-Hudson Valley have not been studied on a regional basis since the early nineteen-forties. These studies dealt with the meso- to macro-scale landscape features and their inferred relationships to Late Mesozoic and Early Cenozoic tectonism. They were limited by their reliance on the small scale and relatively crude maps and by the sparse subsurface information that were available at that time. The Holocene history of the area was only mentioned in passing in those studies because of the lack of information concerning Holocene features throughout the region.
Method
Abundant subsurface and surface data have been assembled during the nineteen seventies and eighties that can be used to illuminate the Late Cenozoic drainage history of the area. The modern topographic map and stereo air photo data that are available for eastern New York State can be used in combination with Cultural Resource Surveys, archeological studies, engineering reports, historical records, and newspaper accounts to develop a Late Holocene through Recent geologic history of this region. I have used a sampling of such data to prepare this preliminary report on the Cenozoic drainage of the mid-Hudson Valley from Newburgh to Catskill. I have chosen selected sites west of the Hudson River to illustrate key points in this report.

STOP 1: New Paltz Bedrock Terrace- SUNY at New Paltz Parking Lot
The section of the Wall Kill Valley near the State University College contains a sequence of strath terraces that range in elevation from the Hoogeberg to the Albany Peneplains. Several of these terraces are mappable in the lower Wall Kill Valley. Dissected and glacially scoured remnants of the Hoogeberg Peneplain occur along the western edge of the Marlboro Mountains. This surface is sharply truncated at Clintondale by a 400- to 420-foot surface that can be traced southwest to the State line. The 400- to 420-ft terrace is cut, in turn, by a 340- to 360-ft terrace. This terrace extends through the windgap in the Marlboro Mts known as The Hell. A third terrace lies at 280 to 300 ft. The SUNY at New Paltz campus is built on this terrace. The 280- to 300-ft terrace can not be traced south of Walden. It extends north into the Hudson Valley and west into the upper Rondout Valley.
The Ashokan Peneplain is preserved by the ridge line of the Shawangunk Mts. Monadnocks of the Helderberg and Monticello Peneplains remain as high points along the Shawangunks.

STOP 2: Wall Kill Floodplain
Intersection of Mountain Rest and Springtown Roads
The reach of the Wall Kill downstream from New Paltz is underlain by 200 ft of glacial-lacustrine deposits. These sediments fill a gorge that was cut into the Albany Peneplain during preglacial or interglacial time. The gorge narrows and becomes shallower to the south, and disappears between Wallkill Camp and Wallkill Village. The gorge underlies the Tillson area and passes west of the present Rondout Creek through the Eddyville area (Dineen and Duskin, 1987).
The abrupt widening of the Wall Kill's floodplain between New Paltz and Tillson is controlled by the preglacial topography. The soft glacial deposits allowed the Wall Kill to migrate laterally. Thus, the floodplain of the Wall Kill is 4,000 ft wide in the stream reach between New Paltz and Tillson. It narrows to 500 ft to the south. The floodplain is 15 to 20 ft above the level of the stream channel, and is underlain by 11 to 22 ft of floodplain deposits in the New Paltz area. These deposits tend to become finer-grained towards the surface. The sinuosity of the river in this reach is 1.6. The Wall Kill's floodplain contains Woodland through Late Archaic Indian artifacts, suggesting an age for the floodplain deposits of 700 to 5,000 yr (Len Isenberg, personal communication, Feb. 1987). The Wall Kill is deflected across a rock sill by the large glacial lake delta at Tillson (Dirieen and Duskin, 1987) and flows through a rocky channel to its confluence with the Rondout Creek. The bedrock sill is the base-level control for this reach of the Wall Kill.

STOP 3: Rondout Creek Floodplain at Napanoch
This section of the Rondout Creek's floodplain was mapped during a Cultural Resource Survey by Mr. Mark LoRusso of the NYS Museum (LoRusso, 1986). The floodplain north of the Eastern Correctional Facility is 2,000 to 3,000 ft wide and 6 to 20 ft thick. Several abandoned meanders are visible on its surface. It is developed downstream from a large alluvial fan that lies at the base of the Shawangunk Mountains. The floodplain deposits were intensely tested during the Cultural Resource Survey, but contained very sparse evidence of Indian occupations, although the meager sample of artifacts suggest an Archaic age (LoRusso, 1986).
The site is downstream from the large alluvial fan of the Rondout Creek at the Village of Napanoch. It was built where the Rondout enters its low-gradient middle valley. The upper Rondout drains the rugged foothills of the southern Catskill Mountains. The base-level of the central low gradient area is controlled by a bedrock sill at High Falls. The stream flows across deeply incised glacial lake deposits (Dineen, 1986) that fill a preglacial valley. The preglacial valley is graded to the Albany Peneplain, and is cut into the Ashokan Peneplain. The valley also erodes a section of the Hoogeberg Peneplain.

STOP 4: Esopus Floodplain at Old Tongore Road Town Park
This stop is at the alluvial fan of the Esopus Creek that was built where the Esopus flows off of the Ashokan Peneplain and onto glacial lake deposits that clog a valley cut into the Albany Peneplain. The Esopus Creek's base-level for this reach is controlled by a bedrock spillway at Glenerie Falls. The stream meanders across a 3,000 ft wide floodplain that is 12 to 20 ft thick (Stop 1 in Dineen and Duskin, 1987). The sinuosity of the stream is 1. 2 to 1.3 in this reach. Many oxbows are visible, especially near Kingston. Dr. Len Isenberg noted that many surface finds of Archaic artifacts occur on the surface of the Esopus Creek's floodplain (personal communication, Feb. 1987).
The buried valley contains a narrow inner gorge that is cut to sea level. The inner gorge extends south into the Marbletown area, although it narrows considerably. The Rondout-Esopus Valley contains a sequence of strath terraces that lie between the Hoogeberg and Albany Peneplains. The Albany Peneplain extends into the middle Rondout Valley through the High Falls water gap.

STOP 5: Kingston Point
The "inner gorge" of the Hudson is deeply incised into the Albany Peneplain in the Kingston area. The inner gorge attains depths of 205 ft below sea level. The Castleton strath terrace lies at -80 to -100 ft in this area. The irregular surface of the Albany Peneplain is probably caused by glacial scour of the weak shale beds that lie between the relatively resistant sandstone and limestone layers. The Albany Peneplain clearly extends south as far as the Newburgh-Beacon Bridge.
The Holocene deposits of this section of the Hudson's estuary are predominantly silty sand to sandy silt with abundant organic matter. The deposits overlie an unconformity that was carved into glacial deposits by the Hudson during the long period of lower sea level (12,000 to 4,000 yrs ago). The organic-rich silts and sands were deposited by the Hudson during the later stage of sea level rise. The Holocene unconformity lies at -20 to -30 ft at the Castleton Crossing of the Thruway, at -40 ft at the Rip Van Winkle Bridge, at -80 ft at the Kingston-Rhinecliff Bridge, at -120 ft at Poughkeepsie, and at -90 ft at the Newburgh-Beacon Bridge. The excessive depth at Poughkeepsie is somewhat puzzling, it might be caused by either the presence of a glacial kettle hole, by catastrophic floods during deglaciation (Dineen and Duskin, 1987) or by tidal scour.

STOP 6: Catskill Point
The bottom of the Hudson gorge is over 122 ft BSL at the Rip Van Winkle Bridge. It has been scoured into the Albany Peneplain. Remnants of the Hoogeberg Peneplain might exist at Mount Merino and the Becraft Mts., beyond the east end of the bridge.
The tidal flats and swamps south of the Village of Catskill are the Holocene delta of the Cats Kill. The tidal flats around Rogers Island are the southernmost extent of the Hudson's Holocene delta. Both of these deltas are composed of silty sand.

STOP 7: The Kaaters Kill at Timmerman Hill
The Kaaters Kill's headwaters are in the eastern edge of the Catskill Mountains. The stream flows across the remnant of the Hoogeberg Peneplain and into the Bakoven valley at High Falls. The Hoogeberg is underlain by sandstones of the Mount Marion Formation. The Bakoven valley is underlain by the Bakoven Shales and is bordered on the east by the relatively resistant carbonates of the Onondaga Formation and the Helderberg Group that underlie the Kalkberg (Chadwick, 1944). The Bakoven valley was eroded to sea level by the late preglacial Cats Kill. The Cats Kill entered the Bakoven valley through the dirt gap at Leeds Flats, flowed into the Esopus Valley at Mount Marion, and entered the Hudson's inner gorge through a dirt gap at Wilbur, near Kingston.
The Kaaters Kill flows between deeply incised clay bluffs. These rounded bluffs resemble Dutch colonial baking ovens, hence the name "Bakoven" for the valley (Chadwick, 1944). The bluffs are failing by a myriad of landslides as the Kaaters Kill undercuts their base when it overflows its narrow floodplain every spring. The clays are over 80 ft thick in the Bakoven valley and overlie shale-pebble rich esker gravels. The base level of this reach is controlled by the bedrock sill in the water gap at the Thruway's crossing of the Kaaters Kill.

STOP 8: Lower Palenville Fan
The next four stops will give us an opportunity to examine several features of the Kaaters Kill as it leaves its upland headwaters and debouches onto the Hoogeberg Peneplain or piedmont. The stream begins near North Lake (STOP 13) on the dip slope of conglomerates that are part of the Onteora Formation. It spills over the edge of the Helderberg Peneplain at Kaaterskill Falls and enters the Kaaterskill Clove. It has a high gradient in the Clove. The Clove is carved into the sandstones and shales of the Kiskatom Formation. Many knickpoints have developed on the sandstone beds in the Clove (STOPS 10 and 11). The gradient flattens somewhat when the stream exits from the Kaaterskill Clove and flows across the surface of the Hoogeberg Peneplain. A large alluvial fan has been deposited at the mouth of the Clove.
The Village of Palenville is built at the head of the fan (Fig. 10 and STOP 9). Abandoned braided stream channels (distributaries) traverse the fan's surface. The soil development is very poor on the surface of these sandy, cobbly gravels. The stream abandons its braided habit at the foot of the fan and meanders across the lake clays that mantle the Kiskatom Valley. The stream's gradient across the alluvial fan is 0.034 or 180 ft/mile.
STOP 8 is near the distal edge of the fan. The stream cut next to the the road exposes clean, open-work, imbricated cobbles that are interbedded with muddy matrix supported cobbly gravels. During low stream flow stages, the stream disappears into the open-work cobbles exposed in the streambed. Rock is exposed in the streambed and the stream flows across a rock ledge upstream at the bridge. Large swampy areas lie along the foot of the fan, thus many of the camps in that region are built on stilts.
The muddy gravels were probably deposited as either wet sediment flows during catastrophic floods or as sieve deposits left as the stream waters flowed into the highly permeable channel deposits, and the open-work cobble beds are probably channel deposits of more "normal" flows. The outcrops of ledge rock are "mini-hogbacks" of Mount Marion sandstones that have been incompletely covered by the fan. The stream channel is approximately at the the same height as the adjacent road, so the stream could break through the intervening levee and to spill onto the roadway, thus creating a new distributary!

STOP 9: Red House at Head of Fan, Village of Palenville
The head of the Palenville alluvial fan can be examined at this stop. The Kaaters Kill crosses a bedrock ledge as it exits from the Kaaterskill Clove. The stream gradient is abruptly reduced, causing the stream to deposit the coarse bed load that it carried in the Clove. Many 1-meter diameter clasts are deposited each Spring in the backyards of the people that live next to the creek. A significant number of these boulders are composed of limestone, a lithology that is not native to the Clove. The primary upstream source of limestone appears to be the rip-rap that is emplaced along the roadbed of Route 23A. These limestone clasts might have traveled a mile from their origin in the roadbed! The fan head is deeply trenched by the stream channel. It is composed of coarse-grained material.

STOP 10: Intermann's Bridge
The stream flows in a steep-walled valley upstream from STOP 9. The floodplain is thin in this section, exposures are less than 6 ft thick. The floodplain deposits are also very ephemeral in the Clove - they have been deeply scoured several times since 1890. The bridge and local houses have been swept away in those floods (Bonafede, 1980). The bridge's 1850 foundations are on rock and usually survive the floods, so they are reused in succeeding bridges. Landslides and rockfalls are common in the Clove (Fig. 10; Bonafede, 1980).
The records of the NYS Dept. of Transportation identify many landslides and seeps along the road from Intermann's Bridge to Moore's Bridge (the bridge near Fawn's Leap). The roadbed crosses a buried valley with over 100 ft of "hard to compact red clayey silt with angular gravel" (till) approximately mid-way between the two bridges. The records also note that the road was severely washed-out during a hurricane in 1935.

STOP 11: Fawn's Leap
Fawn's Leap is a geological feature that was made famous by the Hudson River School painters. It is a waterfall that is cut into the top of the Kiskatorn Formation (Fisher and others, 1970). It has formed where one of the major joint sets of the Appalachian Plateau crosses the Kaaterskill Clove (Chadwick, 1944). The Kiskatorn Formation is apparently more resistant to erosion than the overlying rocks; the Clove has a distinct V shaped notch below Fawn's Leap, with a wider, U-shaped valley above. The Kiskatorn Formation also forms steeper slopes along the Catskill Escarpment. Seeps and springs are common in the inner gorge, many of the landslides are associated with the seeps (Bonafede, 1980; NYS Dept. of Transportation).
The stream gradient is 0.040 or 211 ft/mile from Fawn's Leap to the head of the alluvial fan. The Kaaters Kill has carved potholes, grooves and a plunge pool at the falls. Bars composed of very coarse-grained, imbricated boulders occur in the stream channel up-and down-stream from Fawn's Leap. Luanne Whitbeck (personal communication, Fall, 1983) noted small trees growing on the bars that were of approximately the same age (-10 to 15 years old). She suggested that the trees indicate that the bars were not active in 1983, and that the trees probably began growing during a drought when the stream flow was low. She also observed active landslides along the channel sides.
The floodplain is still quite thin in this reach. Large alluvial fans or cones have been deposited at the mouths of the high-gradient tributary streams in the Clove. Air photo analysis and field work by Dineen, Whitbeck, and Lorie Dunn have documented abundant evidence for landslides, rockslides, earthfalls, and earthflows in this reach. Bonafede (1980) cites several nineteenth century maps that document similar features in the Clove.

STOP 12: Tannery Mill and East Hunter
This 0.5 to 0.75 mile hike follows the floodplain of the stream. The high embankment of Route 23a is on the right (north). Many examples of earthfalls can be seen in the channel banks. The exposures along the stream show that the floodplain deposits are 1 to 2 meters thick, and are composed of imbricated flat cobbles overla1n by a thin veneer of silt. The gradient of the stream in the reach from Haines Falls to Fawn's Leap is 0.046, or 241 ft/mile.
We will pass a large (3 by 4 by 4 meters in diameter) boulder on the bank that was called "Rockefeller Rock" because of an inscription carved into the sandstone (Bonafede, 1980). That boulder had moved 5 to 10 cm away from the bank from 1979 to 1984 (Martha Costello, personal communication, Winter, 1985).
Our trek ends at the defunct East Hunter Tannery. This tannery complex and village were built in 1817 and abandoned by 1866 (Bonafede, 1980). The village is being buried by mass movements. The tannery shows abundant evidence for stream scour and deposition. The mill dams that used to serve the tannery have been washed away.
Bonafede (1980) was not able to document the presence of artifacts that were more than 200 years old, in spite of an intensive search that included many shovel test pits. This observation suggests that the Clove gets "flushed out" regularly by. the Kaaters Kill, a hypothesis that is strengthened by the evidence for mass wasting and flooding and by Route 23A's severe maintenance problems (NYS Department of Transportation).
The "horseshoe" where the road crosses the Kaaters Kill below Kaaterskill Falls is underlain by over 49 ft of red glacial till, based on NYS Dept. of Transportation test boring data. Landslides occur frequently in the area of the horseshoe (Frank Irving, personal communication, Summer, 1987).

STOP 13: North Lake: Catskill Mountain House
The North and South Lake area is a State Park, and is the headwaters for the Kaaters Kill. It is developed on the dip slope of the Onteora Formation, the rock that forms the caprock of the Catskill Escarpment. Glacially striated conglomerates are exposed around the lakes. A major mountain inn served tourists in this area throughout the late nineteenth and early twentieth centuries (Bonafede, 1980). Its abandoned hulk burned about twenty years ago. The inn was built at the edge of the Catskill Escarpment.
The park is on the Helderberg Peneplain. The view from the Escarpment overlooks the Hoogeberg and Albany Peneplains. The Helderberg Plateau-Hamilton Hills are visible to the north. To the east lie the Taconic Mountains, and to the northeast the Rensselaer Plateau can be seen. The Rip Van Winkle and Kingston-Rhinecliff Bridges can also be seen from this vantage point.
The inn and the magnificent scenery lured many geologists into the North Lake area through the years. Darton (1895) suggested that the Kaaters Kill and the Platte Kill to the south have pirated the headwaters of the Schoharie Creek. These high gradient streams had a major advantage over the Schoharie in that they had only to flow 7 to 10 miles to reach their base level at the Hudson, while the Schoharie waters had to flow 135 miles to reach the same point.
Rodgers (1987) wondered why the piracy took place as late as the Pleistocene. He suggested that the back-tilted edge of the Onteora Formation was so resistant to erosion that it impeded the headward extension of streams in the Hudson Valley for a long time. He also suggested that the Kaaterskill Clove was excavated by the stream in post-glacial time.
The NYS Department of Transportation drilled through 65 feet of compact till along the right-of-way of Route 23A from Intermann's, Bridge to Haines Falls, so both the upper, wide valley of the Clove and the narrow gorge below Fawn's Leap are pre-Wisconsinan in age. The till must be studied in more detail to determine whether earlier glacial deposits are present.

C: STRUCTURE AND STRATIGRAPHY ABOVE, BELOW, AND WITHIN
THE TACONIC UNCONFORMITY, SOUTHEASTERN NEW YORK
Jack B. Epstein and Peter T. Lyttle
U.S. Geological Survey
Reston, Virginia
INTRODUCTION
In the early Paleozoic, carbonate banks lay along the east coast of the ancient North American continent. In Ordovician time, plate convergence commenced the closing of the ancient proto-Atlantic ocean (Iapetus) and a deep basin developed into which thick muds and dirty sands were deposited, These were later to harden and become the Martinsburg Formation. Later still, with continued compression, the sediments were folded and faulted during the complex deformation of the Taconic Orogeny. In the field trip area the trend of these folds and faults is about N 20° E. These structures become less intense westward. Following Taconic deformation, mountains rose to the east and coarse sediments were transported westward and deposited as sandstones and conglomerates of the Shawangunk Formation across beveled folds of the Martinsburg Formation. However, a thin diamictite with exotic pebbles records a heretofore unreported geologic episode which occurred during the Taconic hiatus, As the mountains were worn down, finer clastic sediments and carbonates were deposited more or less continuously through the Middle Devonian. Clastic influx during the Middle Devonian records a later orogeny, the Acadian, It is probable that the structural effects of this orogeny did not extend as far west as this field trip area; the limit of Acadian folds, faults, and igneous intrusions lies to the east. Finally, near the end of the Paleozoic, continental collision deformed all rocks, down to and below the Martinsburg. The trends of these later (Alleghanian) structures are more northeasterly.
On this field trip we will develop new interpretations of Ordovician and Silurian stratigraphy, demonstrate structural zones at the limits of Taconic deformation, investigate the relative effects of Taconic, Acadian, and Alleghanian deformation in southeastern New York, and discuss the strange goings-on in a thin enigmatic unit at the unconformity between the Martinsburg and Shawangunk Formations. We will see a variety of complex structures within three Taconic tectonic zones (Stops 1, 2, 5, 6, 7, and 8), examine the nature of, and deposits at, the Taconic unconformity (Stops 2, 5, and 8), review some of the proposed facies relationships in Silurian rocks (Stops 3, 7, and 8), and, weather permitting, look out over the regional geology from high atop the Shawangunk Mountains during lunch (Stop 4).
In the case of disastrous weather, alternate Stops lA and/or lB may be substituted for Stop 1. These stops would allow a brief look at a melange zone of Taconic age, albeit not as spectacular as at Stop 1, and a thrust fault zone of Alleghanian age, both in the Martinsburg Formation.

C: STRUCTURE AND STRATIGRAPHY ABOVE, BELOW, AND WITHIN
THE TACONIC UNCONFORMITY, SOUTHEASTERN NEW YORK

Leave parking lot of Ramada Inn Motel.
Locality is on blacktop of Holocene age, unconformably overlying stream and lake-bed deposits of Pleistocene (Woodfordian) age, unconformably overlying either the Onondaga Limestone or Bakoven Shale of Middle Devonian age.

Fault in the Bakoven Shale
About one third mile straight ahead on the north side of NY 28 is a fault in the Bakoven Shale (noted by Pedersen and others, 1976, p. B-4-21), The fault zone is about 5 feet thick and consists of crumpled and slickensided black shale with abundant quartz veins. The slickenlines and verging of the folds indicate that the overriding beds moved to the northwest.
Some workers believe that these are the youngest rocks deformed in the area and therefore date the folding in Silurian and Lower Devonian rocks as Acadian. However, we believe that there is evidence to suggest that this deformation is Alleghanian (see section on Age of Deformation).
2.1 miles northeast of the fault in the Bakoven is a fault duplex about 5 feet thick, slightly higher in the section in the Mount Marion Formation. Slickensides in the duplex indicate that the overriding beds moved N 70° W. Pedersen and others (1976, p. B-4-6, 7, 22,23) consider these structures to be soft-rock "pull aparts". However, a 1-foot-thick sandstone bed is deformed into mullions and is surrounded by slickensided surfaces and sheared shale. Tectonic shortening is estimated to be 50-60 percent, judging from the overlapping of the mullions.

Fault in Bakoven Shale described above can be seen to right.
For the next 8 miles we will be riding along a flat plain underlain by floodplain and stream-terrace deposits of Esopus Creek and glacial lake-bed sediments of Pleistocene Lake Stone Ridge (Dineen and Duskin, 1987).

Shales and sandstones of the Mount Marion Formation.
The hills in foreground to right are underlain by shales and sandstones of the Mount Marion Formation. In the hills above are sandstones of the Ashokan Formation. Valleys which trend N 20° E. are parallel to lineaments that are very apparent on radar imagery and topographic maps. The valleys, seen for the next two miles, are controlled by very closely spaced joints and minor faulting. The lineaments extend northward up into rocks as young as the Plattekill Formation of Middle Devonian age and may extend into the Oneonta Formation of Late Devonian age. Southward, these lineaments parallel faults that have been mapped in the Shawangunk Formation of Silurian age. This is one of the reasons for suggesting that the deformation in the area is Alleghanian, rather than Acadian, in age.

Cross Esopus Creek.
For the next several miles we will see scattered exposures of the Onondaga Limestone poking through glacial cover.

View of Mohonk Lake tower on Shawangunk Mountain at 2 o'clock.
The tower affords an excellent view of the Catskill Mountains, Walkill Valley, and surrounding region. It overlooks a gorgeous lake at the Mohonk Mountain House which is situated at the crest of a faulted anticline.

Outcrops of the Schoharie Formation.

Cross Rondout Creek.
Classic section of High Falls Shale, Binnewater Sandstone, and Rondout Formation to left.

Exposures of uppermost Shawangunk Fm in low cliff one block ahead

Canal Museum on left.

Cross Coxing Kill.

High Falls Shale, Binnewater Sandstone, and Rondout
Exposure of High Falls Shale, Binnewater Sandstone, and Rondout Formation in steep slope to left.

Mossy Brook Road on right.
If you hike about 0.5 mile down this road, which is on private land belonging to the Mohonk Mountain House, you will find an old log cabin. Nearby, the Mohonk Lake thrust fault is beautifully exposed in Mossy Brook, This gently southeast dipping fault carries Ordovician Martinsburg Formation northwestward over the Silurian Shawangunk.

Exposure of red beds of High Falls Shale on right.

Exposure of Shawangunk on right.

Cross Mohonk Lake thrust fault
Cross Mohonk Lake thrust fault, which carries shales of the Martinsburg Formation, here dipping moderately to steeply towards the southeast, northwestward over quartzites and conglomerates of the more gently southeast dipping Shawangunk Formation. This fault is not exposed where it crosses the highway.

Outcrops of the Martinsburg
For the next 0.7 mile we pass outcrops of the Martinsburg, consisting of thin-bedded shale, minor siltstone, and very rusty weathering, fossiliferous, fine-grained graywacke in beds up to 3 inches thick. Cleavage is poorly developed.

Exposures of slumped Martinsburg on left.
View of Catskill Mountains on right.

Straight ahead, and following the stream valley, is the Kleine Kill thrust fault.
To the right are exposures of deformed Shawangunk and the slope to the left is underlain by deformed Martinsburg.

Martinsburg in bank on right.
For most of this outcrop the southeast dipping shales and graywackes are right side up; however, there are several zones about 3 feet wide that are very tightly folded. The azimuth of these folds vary from N-S to N 10° E, and they plunge gently to both the north and south.

STOP 1A. FAULT ZONE IN FOSSILIFEROUS MARTINSBURG
The Martinsburg in this outcrop is dominantly medium dark-gray shale interbedded with fine grained graywacke. The graywacke beds are commonly less than 5 inches thick, and exhibit graded bedding, and parallel and cross laminations. The graywackes are fossiliferous (mostly brachiopods and crinoids) and contain a fair amount of pyrite. The fossils are most easily seen in the very rusty weathering pyrite-bearing graywacke beds. A cleavage is poorly to moderately well developed in the shales, although not enough to call these rocks slates.
The Martinsburg in this shale pit contains fault-related structures interpreted to be of two different ages. A melange or broken formation, best seen at the far north end of the pit (at least at the time of this writing), is part of the same melange zone seen at STOP 1. The melange zone is Taconic in age and has a strike of N 5-10° E. It has been carried westward over the Silurian Shawangunk in the hanging wall of the younger Kleine Kill thrust. Most of the small faults and slickensided surfaces that are common in this pit are probably related to this younger thrust fault. The trace of the Kleine Kill thrust nearby has a strike of N 15° E, and is interpreted to be Alleghanian in age.
Based on our mapping, several generalizations can be made about Taconic and Alleghanian fault-related structures. The fault zones in the Martinsburg which clearly do not cut Silurian and younger rocks generally have: a) a trend more northerly than the northeast-trending folds and faults in the Silurian rocks, b) a diagnostic scaly cleavage (see STOP 1 for a fuller discussion), c) tightly folded "floating" knockers of graywacke whose axes plunge predominantly to the northeast with variable azimuth, and 4) very little, if any, vein quartz. The faults that definitely cut both the Ordovician Martinsburg and the Silurian Shawangunk, and which we interpret to be Alleghanian in age, generally have: a) a slightly more easterly strike, b) well-developed "pencils" in the shales formed by the intersection of bedding and cleavage, and c) vein quartz parallel to bedding and/or cleavage that commonly contains shale fragments.
An example of a good Taconic melange can be seen at STOP 1, and an example of an excellent Alleghanian fault zone can be seen at Alternate STOP 1B.

View of Wallkill Valley to right (southeast).

Martinsburg shales to right and at bend in road.
Excellent exposures of Martinsburg shales to right and at bend in road. Thin-bedded, graphitic shale interbedded with thin- to medium-bedded, parallel-laminated, fine-grained, pyritiferous graywacke. Cleavage is poorly to moderately well developed and oriented nearly parallel to bedding.

Park on right and disembark.
Climb hill along dirt road with switch back, After walking approximately 1,000 feet you will reach the intersection of Forest Drive and Oakwood Drive; continue straight ahead on Oakwood Drive. Between here and Stop 1 Oakwood Drive marks the boundary between the lands of the Mohonk Mountain House and the Mohonk Preserve, which is also a hunting boundary.
PLEASE BE AWARE THAT BOW AND ARROW HUNTERS MAY BE LURKING IN THE WOODS. NO DEER IMITATIONS ALLOWED.
After about 1,800 feet you will cross Kleine Kill Road. Continue another 50 feet on Oakwood Drive and follow it around a sharp bend to the right (northwest). For the next 750 feet until we reach Stop 1, pay attention to the outcrops of Martinsburg on the right. You should be able to find tight folds, overturned bedding, slickensided fault surfaces with and without vein quartz, and tension gashes in sandstone beds. We will not spend much time discussing these rocks until we reach STOP 1.

STOP 1. MARTINSBURG MELANGE
At this stop we will see a good example of a tectonic melange within the Martinsburg Formation. As there are no identified "exotic" blocks in this melange, it perhaps should be called a broken formation (Hsu, 1968). As you can see by looking to the northeast, we are very close to the Shawangunk cliffs beneath Skytop Tower. Although there are no exposed contacts showing unfaulted Shawangunk resting unconformably on Martinsburg melange in the field trip area, there are several localities in the Rosendale quadrangle to the east where Silurian rocks directly on strike with Martinsburg melange zones show no comparable deformation or offset. In addition, mapping by Vollmer (1981) just southwest of Albany, New York documents a beautiful exposure of unfaulted Rondout Formation resting unconformably on top of Taconic melange in the Normanskill Shale. For these reasons we feel that this melange zone, as well as similar ones nearby in the Martinsburg, must be Taconic in age. In the Kleine Kill valley down the hill and less than 1,000 feet to the west of Stop 1, is the main trace of the Kleine Kill thrust fault, which a short distance to the north offsets and folds the Shawangunk, This fault is part of an imbricate splay, or perhaps a duplex. It would appear that the melange zone seen at Stop 1 and several other places along strike is always contained in the hanging wall of the Kleine Kill thrust fault. Since there are thrust faults that postdate and transport these melange zones, it is particularly important to document structures that appear to be diagnostic for the melanges. The most important feature which can be seen at this stop is a scaly, anastomosing, phacoidal cleavage that commonly exhibits shiny and smeared surfaces. In addition, bedding is very disrupted and many tight folds are rootless and "floating" in the phacoidally cleaved shale and siltstone. Both of these features are most easily seen by exam1ning the two to six inch graywacke beds. As one might expect, the hinge lines of the rootless folds show a significant range in orientation; however, they generally plunge moderately to steeply to the NNE. By carefully examining small scale structures such as asymmetric folds, minor offsets, and slickensides, it is possible to determine the sense of movement on some of the faults. What is difticult, if not impossible, to prove is whether an individual fault formed during the Taconic melange-forming episode or is related to the later, probably Alleghanian thrust system. It is possible, however, to show that although most small-scale structures show an east-over-west sense of rotation and a west-northwest transport direction, there are quite a few examples of thrusts with the opposite sense of movement.
There are two good exposures of the Kleine Kill thrust fault in the bed of the Kleine Kill just west of this stop. These outcrops are remarkably different from the melange seen here. They show sharp, planar, knife-edge faults with minor brecciation but no wholesale bedding disruption. They also contain many quartz slickensided surfaces. Most of these slickensides show an east-over-west thrust sense; however, a number of slickenlines are subhorizontal and suggest that there is a component of strike-slip displacement. The sense of movement is ambiguous, but appears to be left lateral. The shales near the fault commonly show an excellent cleavage (they are almost slates) and are beautifully pencilled.

Shawangunk Formation and the Mohonk TowerPlacemark
Excellent view to right of cliffs of the Shawangunk Formation and the Mohonk Tower. The hills in the middleground are underlain by shales and graywackes of the Martinsburg Formation, trending northerly with angular discordance under the Shawangunk.

Overturned shales and thin graywackes of the Martinsburg Fm on right.
There are a number of narrow fault zones with vein quartz. This outcrop is roughly on strike with Alternate Stop lB

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Overturned Martinsburg shales and thin graywackes on right
Steeply dipping and overturned Martinsburg shales and thin graywackes on right. View of the Shawangunk cliffs at the Trapps straight ahead

Martinsburg with 2.5 ft graywackes on right.
Bedding appears to be right-side-up, however, the poorly developed cleavage in the shales dips steeply to the west suggesting that both bedding and cleavage have been rotated by faulting.

STOP 1B. FAULT ZONE AT GANAHGOTE--MARTINSBURG FORMATION
The shales and graywackes of the Martinsburg in this long roadcut have been severely faulted. This locality was chosen as an alternate stop in order to show the small-scale structures related to what we and others (Kalaka and Waines, 1986) interpret as a major thrust fault of Alleghanian age. Several difficulties arise when trying to document this age: 1) The extent and thickness of glacial materials in the Wallkill Valley prevents the reliable tracing of structures over great distances. 2) This locality contains no rocks younger than the Martinsburg of Ordovician age. Therefore, at this specific locality it is impossible to prove the fault is younger than Taconic. This fault was first referred to by Kalaka and Waines (1986) and they will probably visit this locality on Trip H (this guidebook).
There are at least two ages of quartz slickensides at this stop. The oldest slickensides are parallel to bedding, show movement to the northwest, and were later folded by the tight folds produced during faulting. Unfolded slickensides also formed along these late faults and again show east-over-west movement. In addition, vein quartz found along faults can contain broken pieces of shale. The faults vary in strike from N 10° E to N 50° E and dip gently to moderately to the southeast. Cleavage, though present throughout the outcrop, is more intensely developed near the NE-trending thrust faults. It is in these localities that the rock is intensely pencilled. Based on our mapping in this region, the best examples of pencil shales occur near the younger faults that cut both Ordovician and Silurian rocks, At this outcrop it is common to find bedding and folds abruptly truncated by faults, but the total disruption common to the melange seen at Stop 1 is missing. While one can find smearing along cleavage planes and some anastomosing fabrics at this outcrop, the pervasive scaly cleavage so beautifully developed at Stop 1 is also missing.
About 0.5 mile southwest of Stop lB along the Shawangunk Kill are a series of excellent exposures of the middle part of the Martinsburg that we are informally calling the sandstone at Pine Bush (see section on Ordovician stratigraphy). For a distance of at least 2,000 feet along Shawangunk Kill the entire section is overturned. These outcrops appear to be in the footwall of the thrust fault seen at this stop. However, the total width of the fault zone is not known and there appears to be some faulting at the west end of the Shawangunk Kill exposures. In addition, data from the nearby Delaware aqueduct suggests that the 2,000 feet of overturned Pine Bush might be a sliver caught in the fault zone. About 3.2 miles to the north of Stop lB on Route 299 (Roadlog mileage 21.6 to 22.4) a minimum of 4,000 feet (perhaps as much as 6,000 feet) of Martinsburg is overturned or close to vertical. Also, it would appear that the thrust is cutting up section towards the north since it is approaching the contact with the overlying Shawangunk Formation. It is most likely that this fault is the same as the Mohonk Lake thrust fault. They both have minimum offsets of several thousand feet. In the Mohonk Lake area, the stiff and thick-bedded Pine Bush is virtually absent and the thinner bedded shales and graywackes of the upper Martinsburg (Mamakating) do not appear to be regionally overturned. Locally, for distances of a few tens of feet the rocks may be tightly folded and overturned.

View of Shawangunk Formation on cliff face straight ahead.

Martinsburg on left

Martinsburg is well exposed
From here to the unconformable contact with the Shawangunk near the top of the mountain the Martinsburg is well exposed. The rocks are predominantly shale interbedded with thin-bedded (up to 5 in), crossbedded to planar laminated siltstone, and minor fine-grained sandstone. Soft-sediment slump folds are common in the siltstones. Cleavage is absent or very poorly developed, except near tight folds and narrow fault zones. Most of these folds and faults do not affect the overlying Shawangunk and must be Taconic in age. They trend from N 5° E to N 20° E, while structures in the overlying Shawangunk trend more easterly.

To the left is a turn off with a nice view of Wallkill Valley.

Buried contact of Martinsburg and Shawangunk.
This area of the "gunks" is very popular with rock climbers, often as "thick as pigeons" (R. Waines, oral commun., 1983). The contact is exposed at two spots about 400 feet southwest of the road at the base of the cliffs. Fairly regular and linear mullions are seen in the basal Shawangunk at the contact.

Pass under Trapps bridge.
Conglomerates and quartzites of the Shawangunk dipping moderately to the west.

Cross Coxing Kill.
Here the Coxing Kill valley coincides with the trough of a broad open syncline that plunges gently to the northeast. It is also the site of much nude bathing. For the next 0.5 mile we will begin to cross a broad open anticline that exposes a window of Martinsburg that is approximately 2 miles long.

Poor exposure of Martinsburg to left.

Exposure of basal Shawangunk to right
Exposure of basal Shawangunk to right with unconformably underlying shales of the Martinsburg exposed about 40 feet away. Dips in both units are very gentle and the angle of unconformity is as little as 2°. However, the divergence in strike is as much as 38°, with the strike in the Martinsburg being more northerly. The Martinsburg here is in the broad open-fold Taconic tectonic zone.

Cross Peters Kill.

Cross Sanders Kill.

Upturned beds in Shawangunk mark a fault here.

Overview on right of Rondout Valley
Overview on right of Rondout Valley, underlain by Upper Silurian through Middle Devonian rocks which are buried by a variety of glacial sediments, and the Catskill Mountains, underlain by Middle and Upper Devonian clastic rocks of the "Catskill Formation". Moderately dipping quartzites and conglomerates of the upper part of the Shawangunk on left.

Cross Stony Kill

Roadcut in tongue of the Shawangunk
Roadcut in tongue of the Shawangunk consisting of distinctive light- and dark-gray, crossbedded, slightly conglomeratic quartzite.

Cross Rondout Creek.

U.S. 209 follows the Rondout Valley
U.S. 209 follows the Rondout Valley, here underlain by rocks from the uppermost part of the Shawangunk Formation, then through a sequence of Upper Silurian through Middle Devonian limestones, shales, sandstones, and siltstones. Exposures are poor because of cover by glacial drift.

Cross Vernooy Kill.

Gravel pits in glacial delta
Gravel pits in glacial delta to right and lake clays of glacial Lake Wawarsing under flat plain to left (Rich, 1934; Heroy, 1974). Glacial Lake Wawarsing was dammed in the Rondout Valley between the recessional moraine at Phillipsport (mileage 65.2) and the retreating ice front. The top of the deltaic deposits are at approximately 600 feet altitude, showing that the lake was about 300 feet deep here. The lake enlarged during recession, it dropped as lower outlets were uncovered, and finally drained as the ice retreated past the northeast end of the Shawangunk Mountains near Rosendale.

Sand and gravel pit to right.

Eastern New York Correction Facility
Eastern New York Correction Facility, a maximum security prison, servicing many gentlemen from the New York City area, to left. There is an excellent exposure of the Martinsburg-Shawangunk contact, about 20 feet long, at an altitude of 600 feet. The angular discordance between the two formations is 4°; the Martinsburg here is in Taconic tectonic zone 3. The Shawangunk dips 22° NW in the northwest limb of the Ellenville arch. Mullions are prominent on the basal Shawangunk surface, and there is a shear fabric in both the Martinsburg and Shawangunk.

View of the Shawangunk Mountains in the NW-dipping limb of Ellenville arch to left.

Mount Marion Formation
Exposures of shaly siltstone to very finegrained sandstone of the Mount Marion Formation, dipping 56° NW, to right. Field to left covered by glacial deposits except for one exposure of Onondaga at airfield.

Cross Beer Kill.
A fine example of a slump deposit with disrupted bedding in the Mount Marion Formation is exposed 800 feet up the creek to the right. This outcrop may be within the Alcove Conglomerate of Wolff (1977).

View of North Gully in Shawangunk Mountain straight ahead.

Cross Sandburg Creek.

The Ellenville zinc-lead mine and a rock quarry
The Ellenville zinc-lead mine and a rock quarry in the tongue of the Shawangunk are located at the base of the mountain to the left. See Sims and Hotz (1951) and Rutstein (1987, p. 116) for descriptions.

Cross North Gully
Exposures of the tongue of the Shawangunk in roadcuts and tongue of the Bloomsburg in the creek bed of North Gully to the left.

Red beds of tongue of the Bloomsburg to left.
Till and moderately NW-dipping Shawangunk higher along road towards Mt. Meenahga.

View to right
View to right of the valley of Sandburg Creek, the Nevele Country Club, and the Catskill Mountains.

Conglomerates of basal Shawangunk on left.

Uppermost Martinsburg on left.

Contact between Martinsburg and Shawangunk at base of low cliff on left.

STOP 2. CONTACT OF MARTINSBURG AND SHAWANGUNK
CONTACT OF MARTINSBURG AND SHAWANGUNK; SHALE-CHIP GRAVEL AT TACONIC UNCONFORMITY; UPPERMOST MARTINSBURG IN TACONIC OPEN-FOLD FRONTAL ZONE; CLEAVAGE IN SHAWANGUNK
Take a peek to the northwest through the bushes at the broad glacial valley of Sandburg Creek and the Catskill Mountains beyond. The valley is underlain by glacial lake sediments, deposited in glacial lake Wawarsing between the morainal dam at Phillipsport, 5 miles to the,southwest, and the receding ice front. Also note the graffiti-covered, unevenly and planar bedded conglomerates with low-amplitude channels in the lower Shawangunk Formation. The contact with the underlying Martinsburg Formation is near the base of the low cliff. In this area the strike of the two formations is similar, but the Martinsburg dips 10 to 15 degrees less than the Shawangunk.
Locality A:
Walk 300 feet down the road to the exposed contact of the Martinsburg and Shawangunk.
The Shawangunk consists of planar bedded, quartz-pebble conglomerate with rounded to subangular vein quartz pebbles as much as 2.5 inches long, and planar bedded and crossbedded, conglomeratic, medium- to coarse-grained, feldspathic quartzite. Chert pebbles are rare. There are no pebbles derived from the underlying shales and graywackes of the Martinsburg Formation.
The Shawangunk forms a two-foot overhang above the underlying rock, which is at least 1.5 feet thick and consists of a mass of shale chips with an openwork texture. The chips are up to about 1 inch long and form a crude foliation approximately parallel to the overlying contact with the Shawangunk, although this foliation is interrupted in places. It might be suggested that these rocks were jammed by man under the Shawangunk, but the unit below the Shawangunk is clearly in place. The only explanation for this unit that we can think of is that it is a shale-chip gravel, deposited on and derived from a sloping Martinsburg surface. The shale chips are flat and generally equidimensional on their flat surface. There is no secondary cleavage in the chips, as far as we can tell. This suggests that cleavage was not imposed upon the Martinsburg prior to the deposition of the gravel. Thus, slaty cleavage at this locality did not form during Taconic deformation.
The gravels in the Martinsburg are remarkably similar to Pleistocene shale-chip gravels derived from Paleozoic shales in the central Appalachians, both in physical appearance and size-distribution characteristics.
If this is indeed a colluvial deposit, the geologic relations in this area indicate that the Martinsburg was gently folded during Taconic deformation, it was uplifted and exposed with a steep enough slope to develop a colluvial shale-chip gravel, and was later covered by conglomerates (believed to be fluvial) of the Shawangunk Formation.
Locality B
Walk another 700 feet down the road to exposures of uppermost Martinsburg bedrock,
The Martinsburg here consists of thin-bedded grayish black shale with some thin beds of olive-gray, very fine grained, crossbedded graywacke, capped by thin Pleistocene till. Note the lack of cleavage in the shales. The Shawangunk 40 feet above has the same strike, but dips 10° more steeply. This gentle angular discordance between the two units is typical not only for the Ellenville area, but for many miles to the northeast (to Ruedemann's Line, fig. 9) and to the southwest through New Jersey into eastern Pennsylvania (Epstein and Lyttle, 1987). This relationship is typical of the open-fold Taconic frontal zone.
Locality C
Walk another 600 feet downhill to the road intersection and the Shawangunk outcrop.
Bedding in the Shawangunk dips 40° NW here, getting steeper as we head farther northwestward into the steep limb of the Ellenville arch. The conglomerates in Shawangunk contains closely spaced fractures cutting through the quartz pebbles and sand matrix. In places a residual thin film of mica and opaque minerals along the cleavage folia shows that this is a pressure-solution phenomenon. This type of cleavage is common in the Shawangunk in New Jersey and New York. Because bedding-plane slickensides are not common in this area, it is hypothesized that shortening during folding of the Shawangunk was taken up by development of cleavage. In eastern Pennsylvania, where folding is tighter and there has been much accommodation by bedding-plane slippage, there is little cleavage in the conglomerates and quartzites.

Tongue of the Bloomsburg Redbeds on left.
The road follows this unit for several hundred feet.

Outcrops of uppermost Shawangunk in flatirons on NW limb of Ellenville arch.

Cross South Gully.

Site of Stop 3 on left.

STOP 3. Stratigraphy And Sedimentation Of The Shawangunk Formation
Pull off on shoulder to right. Cross road and walk 0.1 mile down to Stop 3.
CAUTION--WALK ONLY ON SHOULDER. THIS ROAD IS HEAVILY TRAVELLED! NO REFUNDS IF YOU ARE HIT.
The upper half of the Shawangunk Formation is exposed here and consists of cross-bedded and planar-bedded conglomeratic quartzite and pea-gravel conglomerates, with minor thin, lenticular light-olive-gray shale. Channels are abundant and many beds pinch out along strike. Shale drapes in crossbeds are common. Flattened silty shale balls up to 8 inches long are seen on the lower exposed bedding surface. Crossbed trends throughout the area of this field trip are to the northwest. The sedimentary structures, current trends, and petrographic characteristics suggest a fluvial, braided stream environment of deposition, similar to the interpretation for the Shawangunk in eastern Pennsylvania (Epstein and Epstein, 1972).
We will discuss some of the regional stratigraphic correlation shown in fig. 3.
The beds dip about 45° NW, They are interrupted by a kink fold whose axis trends 18° S 56° W, a more easterly trend than the regional strike of the beds. This fold, and scattered others in this part of the Appalachians, may represent a later stage of Alleghanian folding.
If the leaves are off the trees, you may be able to see the linear valleys in the Catskill Mountains to the north. These are discussed under "Age of post-Taconic Deformation".

Small thrusts in Shawangunk to left.
These have a strike similar to the kink axis at Stop 3 and may also be later structures.

Upper quartzite member of Shawangunk.
Launch site for hang gliders straight ahead.

Shale unit of Shawangunk on left.

Back into overlying quartzite unit.

STOP 3A.
Shale unit of Shawangunk to left, nice view at turn off to right. Pull off for Alternate Stop 3.
To the right (northwest) is the flat-floored valley of Sandburg Creek underlain by glacial lake clays, In the far distance to the north the hills are underlain by sandstones of the Ashokan Formation, and in the far distance to the north are the higher Catskill Mountains underlain by Middle and Upper Devonian rocks of the "Catskill Formation". The valleys in the Catskills are aligned along linears that are presumably controlled by structural weakness (see section on age of deformation),
CAREFULLY CROSS THE ROAD
In this area we have been able to divide the Shawangunk into lower and upper units (fig. 3), separated by a shale-bearing sequence about 100 feet thick, The shale unit underlies topographic lows, generally allowing for easy mapping. This unit can be seen at the base of the exposed section, and consists of more than 80 feet of interbedded, laminated, ripple laminated, olive-gray silty shale and moderate-brown and light-olive-gray very fine to medium-grained, crossbedded, lenticular sandstone, slightly conglomeratic in places. Many of the sandstones have sharp channeled bases and some are ripple-topped.
The shale unit is overlain by several hundred feet of thin- to medium-bedded, medium-grained, partly conglomeratic, partly feldspathic, crossbedded, channeled quartzite with scattered thin and lenticular olive gray shale. The quartzites appear to be evenly bedded from a distance, but closer scrutiny shows that they are channeled, lenticular, and unevenly bedded.

Mostly glacial till
Between here and the next stop, the road will be mostly on glacial till, with a few scattered exposures of the Martinsburg.

Martinsburg exposure on left.
This exposure and a few more up the road are in the Taconic tectonic zone of broad open folds. Views of continuous cliffs of the Shawangunk Formation in the broad top of the Ellenville arch may be seen at several places along this road.

Borrow pit on right in Martinsburg.

Entrance to Ice Caves Mountain National Landmark.
If you are quick you might read the educational (??) signs as the bus proceeds.
It is possible that we will not drive to the top of the mountain at Sam's Point. If so, pick up a lunch and take a leisurely 15-minute stroll to Sam's Point along the road to the right. The basal Shawangunk is nicely exposed near the end of the journey.

Slot Rock, a crevasse in the Shawangunk, on your right.

Martinsburg on right.
At this locality the Martinsburg dips 5° more steeply to the southeast than the Shawangunk exposed in the low cliffs above.

Cross Martinsburg-Shawangunk contact.

Lake Marentanza on right.
Many of the Shawangunk surfaces contain glacial striae.

Lake Marantanza
Lake Marantanza, partly dammed by till in a structural depression, on right.

Sign: "There are no fish in this lake...
Sign: "There are no fish in this lake. This is Lake Marentanza. It is the water supply for Ellenville. There are no fish because the rocky bottom does not grow plant life to give off enough oxygen to support fish life. It is a mystery where the water comes from since the lake is on a mountaintop. What do you think?"

STOP 4. SAM'S POINT
REGIONAL OVERVIEW; BASAL SHAWANGUNK; TROUGH CROSS BEDDING; GLACIAL STRIAE; ICE CAVES AND JOINTS; LUNCH
The highest point in the Shawangunk Mountains (2,289 ft) lies 2,000 feet north of this point. From southeast (left) to north (right), you can see (if the day is clear), the New York Highlands underlain by Precambrian rocks thrust on top of Cambrian and Ordovician carbonates and shales of the Wallkill Valley. In front of the Highlands are Schunnemunk and Bellvale Mountains underlain by conglomerates and sandstones of the Middle Devonian Schunnemunk Conglomerate in the Green Pond outlier. The rocks of the outlier are in fault and sedimentary contact with the Precambrian. The details of these structures are far from fully known. Shawangunk and Kittatinny Mountains, held up by the Shawangunk Formation, upon which we stand, next wiggle to the southwest with Tristates Monument marking the highest elevation in New Jersey at High Point (1,803 ft). We already know about the glaciated valley northwest of the mountain. The large white buildings 17 miles due west near Monticello make up the Concord Hotel, the site of several past GSA meetings, Beyond that are the Pocono Mountains of Pennsylvania that blend into the Catskill Mountains of New York to the northeast, underlain by flat-lying rocks of the "Catskill Formation".
The Shawangunk at Sam's Point dips very gently to the northeast, near the broad crest of the Ellenville Arch. Trough crossbedded is well exposed. These indicate current trends ranging between S 80° W and N 70° W. Glacial striae with chatter marks on the bedding surfaces show that the Wisconsinan glacier flowed over the mountain moving S 16° W.
The lower 80 feet of the Shawangunk here consists of medium- to thick-bedded conglomerate with quartz pebbles as much as 2 inches long. Channeled bases are common. Nowhere do we see any pebbles from the underlying Martinsburg, a peculiarity that exists throughout New York, New Jersey, and eastern Pennsylvania, and one which eludes a good sedimentologic explanation.
The Shawangunk is separated into huge blocks tens of feet wide. These have moved apart along the soft shales of the underlying Martinsburg, probably forced apart by frost action and wedging of boulders that fall into the cracks, producing a "moveoutite". This process has gone to a joyous extreme at the Ice Caves, one-half mile to the east, where the joints parallel the cliff face of the mountain. Cold air is trapped in the maze of blocks, and snow may persist throughout the summer, hence their name.

Proceed down over cliff of Shawangunk conglomerates
Proceed down over cliff of Shawangunk conglomerates, crossing buried contact with Martinsburg Formation.

Note the breaking away of large blocks of the Shawangunk along joints

At 11 o'clock are linear valleys in the Catskill Mountains
At 11 o'clock are linear valleys in the Catskill Mountains that mark lineaments seen on radar imagery and described under mileage 1.3.

Mount Marion Formation.
Moderately northwest dipping gray shale, siltstone, and sandstone of the Mount Marion Formation. We will be paralleling these rocks for the next 18 miles. On the left are lake deposits of Lake Wawarsing. This lake was dammed by the moraine at Phillipsport, four miles to the southwest.

Bear Hill to left in Ellenville arch.

Cross Homowack Kill.

Moraine at Phillipsport on left.

Leave moraine.

Parking area on right from which to see gliders on lazy summer days.

Shawangunk mine (zinc-lead)
Wurtsboro airport on left. Shawangunk mine (zinc-lead) on top of Mountain to left (Ingham, 1940; Gray, 1961).

Danny's Restaurant
Danny's Restaurant on left is excellent place for pastrami and corned beef sandwiches.

Exposures of Mount Marion to right.

Cross Basher Kill.

Large erratics of Catskill sandstone on left.

Quarry in New Scotland Formation on left.

Beginning of exposures of Shawangunk Formation on left.

Northwest dipping Shawangunk straight ahead.
In quarry to left are thin shales interbedded with typical Shawangunk quartzites and conglomerates. These are on line with exposures 1.2 miles to the southwest to which Swartz and Swartz (1931) applied the name "Otisville Shale Member of the Shawangunk Formation". This unit is out to lunch, that is, it is poorly defined, should be discarded. It is unmappable, and Clarke (1907) measured the rocks in the quarry and showed that shale makes up less than 3 percent of the section.

STOP 5. TACONIC UNCONFORMITY AT OTISVILLE
This is a classic exposure, discussed by many geologists in the past (Clarke, 1907, Schuchert, 1916, others), and visited by the 34th Meeting of the NYSGA (Fink and others, 1962). All have recognized the angular discordance in bedding between the Martinsburg (N 16° E, 44° NW) and Shawangunk (N 30° E, 28° NW). In this area we are in the broad open-fold zone of Taconic deformation, although these gentle structures are interrupted locally by a faulted overturned fold, seen at the next stop.
The basal Shawangunk conglomerates contain quartz pebbles as much as 2 inches long. No pebbles from the underlying Martinsburg were seen. The lowest few inches is pyritized. The Martinsburg comprises shale with minor thin graywacke siltstones and contains no obvious secondary cleavage.
The basal surface of the Shawangunk is irregular, with downward-projecting mullions that have a relief of about one inch and are about 3 inches to two feet apart. These have a general trend of N 32° E, about parallel to the strike of the beds and perpendicular to the regional transport direction. Note that these mullions are found only at the Martinsburg-Shawangunk contact and are not found on any surface higher up in the section. Some of the lowest Shawangunk is sheared parallel to bedding,
Between the solid Martinsburg bedrock and the Shawangunk there is an unusual zone, as much as one foot thick, containing light-gray to light-bluish gray clay gouge with slickensided quartz veins. This gouge, and the associated mullions in the overlying conglomerates, are typical of most Martinsburg-Shawangunk contacts exposed in southeastern New York and shows that the unconformity is also a plane of movement, the displacement along which is not known.
Also in this zone is a poorly sorted and vaguely bedded diamictite (a non-genetic term referring to a poorly sorted sedimentary rock with a wide range of particle sizes) containing angular to rounded pebbles of exotic types, as well as clasts from the Martinsburg, in a clay-silt matrix. Bedding is generally poor, but some samples collected from the northeast side of the cut show reasonably decent bedding. There is a sharp contact with the Shawangunk above and also a sharp contact with the Martinsburg below; both are unconformable. In places it appears that parts of the Martinsburg have been bodily lifted from the underlying bedrock and incorporated in this diamictite. There are several possibilities for the origin of this unit. We do not believe that it is fault related, because there is no foliation in it. It looks more like a product of mass wasting, and is interpreted to be a colluvial gravel.
The pebbles include types foreign to the immediately underlying bedrock, They are composed of fairly clean quartzite, some of which are pyritic, fine-grained protoquartzite and subgraywacke, red siltstone, medium-gray siliceous siltstone, laminated micaceous siltstone, medium dark-gray shale, graywacke, and vein quartz. Many are rounded, some have a thin weathering rind, and others have surfaces that are weathered in relief. Clearly, these cobbles were exposed to the air, weathered, and incorporated in the diamictite.
One question that needs to be asked is why the clay has remained a sticky clay, whereas surrounding rocks have been lithified? The answer may be that the contact is a zone of alteration. This area of the Shawangunk Mountains contains several abandoned lead-zinc mines and there are many prospects and mineralized localities throughout the area. The lower few inches of the Shawangunk here at Otisville is similarly altered.
Another puzzlement is that the colluvium contains many disoriented clasts of slickensided vein quartz. This indicates fault movement prior to incorporation in the colluvium. Possibly the Martinsburg nearby was faulted and slickensided during Taconic deformation and the slickensided fragments were later incorporated in the colluvium. Another possibility is that the diamictite is a fault gouge and not a colluvium, and there has been several periods of movement, the latest one of which fractured earlier slickensided rocks. The problem with this interpretation is that it does not account for the exotic pebbles nor does it explain the lack of foliation in the diamictite.
WHAT DO YOU THINK?

Covered contact of Martinsburg and Shawangunk.
Exposures of Martinsburg shale and graywacke on left, dipping moderately northwest.

STOP 6. OVERTURNED TACONIC FOLD IN MARTINSBURG FORMATION
The Martinsburg in the Otisville area is generally within the open-fold Taconic frontal zone. However, this locality is complicated by a faulted overturned fold (fig. 17). The Martinsburg here consists of shale and interbedded thin- to thick-bedded graywacke. Sole marks (grooves, flutes, and loads) are prominent on the undersurfaces of bedding in the overturned limb. Cleavage is well developed and is axial-planar to the fold. The axis of the fold trends about N 10°E and is overlapped by the Shawangunk about 1.3 miles to the north. Because the Shawangunk does not appear to be folded at the unconformity, the fold, faults, and cleavage in the Martinsburg at this locality must be Taconic in age. Outside the area of this fold, cleavage is generally not developed. While the map is believed to be accurate, critical parts lie within the boundaries of both a State and a Federal maximum security prison. These areas have not as yet been mapped. The criminal instincts of the senior author of this guidebook may allow him to set up residence here in the near future in order to complete the mapping.

Road to Federal Correctional Institution to left.

Otisville Correctional Facility
Otisville Correctional Facility of the New York State Department of Correctional Services to left. At this point, all those who have disagreed with the interpretations presented on this field trip will be dispatched.

Graywackes of the Martinsburg Formation on left

Lake Altemont on left
Lake Altemont on left; gently dipping Martinsburg shales on right.

Thick bedded graywacke and shale of the Martinsburg on left.

Martinsburg graywacke and shale on right.

STOP 7 ROUTE 17 ROADCUT
STRATIGRAPHY AND STRUCTURE OF THE UPPERMOST MARTINSBURG, THE TACONIC UNCONFORMITY, AND LOWERMOST SHAWANGUNK.
CAUTION. DO NOT FALL OFF ROADCUT. DEATH WILL RESULT
A fine view may be seen from this point. Far to the east (right) are the Schunnemunk and Bellvale Mountains, underlain by the Schunnemunk Conglomerate of Middle Devonian age in the Green Pond outlier. The lowland immediately to the east is the Walkill Valley, underlain by carbonate rocks of Cambrian and Ordovician age, as well as the Martinsburg Formation. Directly under us is a marvelous 3000-foot-long exposure demonstrating the stratigraphy and structure within the Martinsburg. To the west (left) you can see the overlying Shawangunk conglomerate (STOP 8), as well as the tongue of the Bloomsburg and overlying tongue of the Shawangunk. Beyond the bend in the road, and not seen, is the High Falls Shale. Off in the distance are the Catskill Mountains with rocks as young as the Plattekill Formation of Middle Devonian age.
This outcrop offers the best look at the uppermost 60U feet of the shale and graywacke at Mamakating of the Martinsburg exposed anywhere in the Wallkill Valley. Some of the more interesting sedimentologic and structural features are described below and located on figure 18, so that at some future date the field tripper can return and look at the outcrop at his or her leisure. As mentioned in the section on Ordovician stratigraphy, the Mamakating in southern New York differs from both the Ramseyburg and Pen Argyl Members of the Martinsburg that have been mapped in eastern Pennsylvania and northern New Jersey. The Mamakating consists dominantly of thick sequences (hundreds of feet) of medium dark-gray, thin-bedded shale interbedded with with very thin to medium-bedded (1/4 to 15 in), very fine to fine-grained, graywacke. These thick sequences alternate with thinner sequences (generally less than 100 feet) of thin-bedded shale interbedded with medium- to thick-bedded (up to 6 ft), fine-grained graywacke. Locally in both sequences, graywacke makes up more than 50 percent of the outcrop, but a more common average would be less than 25 percent. Only seen at this outcrop, but probably present elsewhere in the Mamakating, is a 40 foot thick olistostrome (fig. 19, near location B, specifically all rocks at ground level between station 50 and 300; fig. 18) with slump folds, flute casts, randomly oriented fissile shale chips, and imbricately stacked thin graywacke beds in a dominantly shale matrix, all of which suggest westward flowing currents. The olistostrome is dominantly shale, but contains some coherent graywacke beds which have incorporated some folded shale rip-ups. Perhaps earthquakes triggered slurries of slump deposits which were then immediately followed by turbidites which ripped up the shale. This olistostrome appears to be in the hanging wall of a back thrust of unknown displacement. A return to this exposure at a later date would be well worth the effort.
Near locality A on Figure 18 is a minor 2 inch thick bedding plane fault at the base of a foot thick graywacke bed. Another 60 feet east (at station 480 on fig. 18) is a graywacke bed with breccia at its base. The breccia contains quartz and calcite crystals and slickensides at its base. The upper block appears to have moved to the southeast.
The most obvious features seen from this vantage point are a number of faults (fig. 18, location C) directly across the highway. All of these structures trend in a more northerly direction than bedding in the overlying Shawangunk, and comparable disruption is not seen in the Shawangunk. Therefore, it seems most probable that these structures are Taconic in age. The thrust fault on the east (right) side of this tepee-like structure has an east-over-west sense of motion, and has produced an excellent cleavage in the gently arched adjacent rocks of the hanging wall. This is all the more evident because cleavage is not well developed, if at all, at Stop 7, except near faults. It is difficult to prove, but this fault is probably the one with the greatest displacement. Framing the west side of this tepee-like structure is a back thrust with unknown, but probably less, displacement. This back thrust cuts a bedding plane fault that probably has had minor movement with most of the strain taken up in little buckle folds, narrow breccia zones, and fractures. In between the two are a host of accommodation faults, which are trying heroically to solve the room problem. With a little patience it is possible for the field tripper to work out a chronology of movement among the many little faults in this area.
About 250 feet to the west (fig. 18, location D) is a complex area with faults of three different ages. From our vantage point across the road it is impossible to see these details, but it is worth discussing. The earliest movement is parallel to bedding and produces quartz slickensides, These slickenlines plunge N. 60° W. and show that the upper block moved northwest. The bedding plane faults are cut by a very steep fault oriented N. 83° E., 80° SE. which has a 6-12 inch gouge. Down-dip slickenlines show that the south block moved up in this case. This steep fault is in turn cut by a third fault oriented approximately N. 70° E., 50° NW, This cross structure may be a much later Alleghanian feature similar to the late kinks seen at Stop 3. Movement on this youngest fault folds the second steep fault and shows down-to-the-northwest movement.
At the 1175 foot marker on Figure 18 (near location E) are beautiful fractures filled with calcite, brecciated shale fragments, quartz, and a brownish-orange carbonate mineral (probably ankerite). These vertical fractures, seen at road level, are oriented N. 11° E. and appear to be caught up in a fault zone about 20 to 25 feet above road level. This fault reaches road level at station 1300 on Figure 18. We interpret this thrust fault as a backthrust, based on folding of bedding in the upper block (presumed hanging wall) and the sense of rotation of the vertical fractures. Some of these fractures were the locus of later movement as evinced by slickenlines oriented 11° 0 N. 11 E.
From station 1300 (fig. 18) west to the contact with the unconformable contact with the overlying Shawangunk at Stop 8, the Mamakating dips gently northwest and is devoid of any complex structures.
D. W. Fisher made three collections of graptolites from the Martinsburg shales of this outcrop, which were reported on by W. B. N. Berry (1970), The species reported by Berry are: Climacograptus spiniferus Ruedemann and Climacograptus typicalis Hall from 16 feet below the contact with the Shawangunk; Climacograptus sp., Dicranograptus nicholsoni var. minor Bulman, and Orthograptus quadrimucronatus var. approximatus (Ruedemann) from 49 feet below the contact with the Shawangunk; and Dicranograptus nicholsoni var. minor Bulman from 138 feet below the contact with the Shawangunk. These fossils are of critical importance to the dating of Taconic events (see section on Ordovician stratigraphy in text) and in establishing the length of the hiatus represented by the Taconic unconformity in southern New York State. Berry puts these graptolites in his upper subzone of zone 13, which suggests the rocks are late Middle Ordovician to early Late Ordovician in age.
Just to the south of where we are standing and approximately 240 feet beneath us is an old abandoned railroad tunnel that Russell Waines kindly suggested we visit. The southeastern 3,400 feet of this tunnel is in the Martinsburg, while the northwestern 400 feet offers excellent exposures of Shawangunk. The mineralized unconformable contact is especially well exposed (for details see Stop 8). Interestingly, a long section of the tunnel that is bricked over so that no rocks can be seen coincides with the most faulted section of the Martinsburg (fig. 18, between localities C and E). A thirty foot wide thrust fault zone (located about 400 feet in from the southeastern end of the tunnel) which, if projected along strike, would be located about 1,000 feet east of the long roadcut of Stop 7. For anyone enterprising enough to visit this tunnel, we would highly recommend a hard hat, and even more importantly, a pair of chest waders at least 5 feet tall; there is always a great deal of water in the north end of the tunnel.

Excellent exposure of olistostrome
Excellent exposure of olistostrome showing slump folds in thick graywacke on left beneath overpass

STOP 8. MARTINSBURG-SHAWANGUNK CONTACT STRATIGRAPHY OF THE SHAWANGUNK-BLOOMSBURG INTERVAL
BE VERY CAREFUL OF HIGH-SPEED TRAFFIC.
This is another fine exposure of the Taconic unconformity in southeastern New York. The rocks of the Martinsburg and Shawangunk are similar to those we have seen elsewhere. The basal foot of the Shawangunk contains much pyrite. The Martinsburg at the contact dips 16° to 31° NW., whereas the Shawangunk dips 25° NW. The angular discordance at eye level is 15°. No secondary cleavage is seen in the Martinsburg at this spot. Graptolites of Zone 13 age (late Middle to early Late Ordovician) were identified by Berry in the Martinsburg within 135 feet of the overlying Shawangunk (Offleld, 1967, p. 53; Berry 1970; see Stop 7).
The character of the zone between the Martinsburg and Shawangunk varies from place to place. Near road level, the zone contains rotated shale fragments with some quartz veins. This is probably a shear zone. Also included in this zone are disrupted shale fragments and a medium dark-gray sticky clay, a fault gouge. To the southeast, where the contact rises to about 20 feet above road level, we found rounded to subangular pebbles and cobbles up to 4 inches long of graywacke, chloritic sandstone, cross-laminated feldspathic conglomeratic quartzite, and red very fine-grained sandstone. Small ribs on the surface of one pebble prove that the clast was weathered prior to emplacement, and is not a fault-breccia fragment. Several pebbles also have distinct weathering rinds. The shape of the pebbles suggest transport of short distances.
As indicated in the section on stratigraphy at the beginning of this guidebook, these findings suggest that there were a series of Upper Ordovician and possibly Lower Silurian rocks that were deposited upon the Martinsburg following Taconic uplift and folding. These were derived from source rocks that are now gone. The potential source areas are presently under investigation.
About 1,000 feet to the west we can see fine exposures of the tongue of the Bloomsburg (called High Falls by Gray, 1961, and Otisville Shale and High Falls by Smith, 1967), overlain by the tongue of the Shawangunk (called Binnewater by both Gray, 1961, and Smith, 1967). About 2,000 feet farther west are rocks which we believe to be part of the High Falls Shale. See the section on stratigraphy for an understanding of these interpretations. The conclusions were based on tracing the various facies in the Shawangunk and Bloomsburg eastward from New Jersey.

Uppermost Shawangunk on left.

Bloomsburg Redbeds - Shawangunk contact
Contact between tongue of the Bloomsburg Redbeds and tongue of the Shawangunk on right.

High Falls shale dipping moderately northwest.

Shawangunk Mine
Shawangunk Mine high on northwest slope of Shawangunk Mountain to right.

View of Ellenville Arch straight ahead.

View of eroded Ellenville arch
View of eroded Ellenville arch producing flatirons in northwest limb of fold on right.

Granit Hotel to right
Granit Hotel to right and water tower at Minnewaska at top of Shawangunk.
2015 OHM: The Granit Hotel is now the Hudson Valley Resort and Spa. A proposal to construct a $750 million casino here in 2014 did not get approved.

Dark gray shales of Bakoven Shale on left.

D: PALEOGEOGRAPHY AND BRACHIOPOD PALEOECOLOGY OF THE ONONDAGA LIMESTONE IN EASTERN NEW YORK
RICHARD H. LINDEMANN
Department of Geology
Skidmore College
Saratoga Springs, New York 12866
HOWARD R. FELDMAN
Biology Department
Touro College
New York, New York 10036
During the three plus decades since Oliver (1954) formally divided the Middle Devonian Onondaga Limestone into its Edgecliff, Nedrow, Moorehouse and Seneca Members, the formation has been the focus of considerable attention. However, with the exception of subsurface investigations, research has concentrated on the formation as seen in outcrop between Buffalo and the Helderberg/Catskill area. Few geologists have ever examined the Onondaga south of its classic exposure in Leeds Gorge. As an arbitrary measure of this, we note that between 1962 and 1986 more than ten NYGSA field trips concentrated on the Onondaga while only one (Oliver, 1962) was sited in southeastern New York. As a result, stratigraphers and paleontologists alike tend to have a somewhat skewed impression of Onondaga paleogeography, a situation we hope this field trip will partially rectify.

D: PALEOGEOGRAPHY AND BRACHIOPOD PALEOECOLOGY OF THE ONONDAGA LIMESTONE IN EASTERN NEW YORK

STOP 1. Onondaga/Schoharie contact can be observed in an abandoned quarry
The trip begins in Wawarsing, New York, approximately 0.5 miles northeast of Vernooy Kill, 100 feet north of Route 209, on the property of Steve and Sue Caruso (Be sure to ask permission before entering outcrop area). The Onondaga/Schoharie contact can be observed in an abandoned quarry (AMNH [American Museum of Natural History] Locality 3151B; see Feldman, 1985) where the Edgecliff Member with characteristic large crinoids, trilobites and some Amplexiphyllum is accessible. The Edgecliff here is finer grained than in the Mid-Hudson Valley and represents the deepest part of the basin to shelf lithology we will see today.

STOP 2. Pull off on the west side of Route 209 (wide shoulder).
On the east side of the road note a transitional, deeper water facies, similar to that found at Locality 1, about 1 meter thick, with 0.5 meter of shallower water, "cleaner" Edgecliff Limestone. The fauna here consists of large crinoids, ?Amplexiphyllum, ?fenestrate bryozoans (weathered), and Syringopora. Note storm layers and a sharp break between two facies.

STOP 3. Here we are higher in the Edgecliff (about 4 meters thick).
The water was shallower and the brachiopods larger. Chondrites is evident here but not further southeast due to the fact that as the ramp deepened (to the southwest) the sediment became too "soupy" for tubelike or tunnel structures.

Entire Lower Devonian section
Note that along Route 199 we are passing through the entire Lower Devonian section, from the Thacher at the base, to the Schoharie, which underlies the Onondaga in this part of New York State

On W side of the road note complex thrust slices oblique to the section

Angular unconformity
Angular unconformity between the Wilbur Limestone Member of the Rosendale Formation (Late Silurian) on Normanskill (Austen Glen aspect) strata.

STOP 4. Note the gradational nature of the Onondaga/Schoharie contactPlacemark
Note the gradational nature of the Onondaga/Schoharie contact which is placed at the uppermost buff-weathering band. Ranging through the upper Schoharie into the lower Edgecliff are massive cyclostome bryozoans often encrusting (e.g. crinoids). Other faunal constituents here include brachiopods, particularly Atrypa "reticularis," and Fistulipora. The stratigraphy at this locality is complicated by faulting and repetition due to thrusting (note slickensides and slip-fiber sheets), thus making the Edgecliff seem to be thicker than it actually is. According to Marshak (1986) there are two major thrusts which display a relatively large stratigraphic throw along Route 9W. The upper one, now covered by the exit ramp, emplaces Esopus Formation on Onondaga Limestone while the lower one, exposed further to the north along the roadcut, emplaces Onondaga Limestone on Schoharie. The upper fault may be the continuation of the Fly Mountain Thrust. In general, there is an absence of favositids between here and Wawarsing, but north of here, especially in Leeds, they are abundant. Note the light-weathering chert.

Note Howard Johnson's on the right
If time permits we will pull into the parking lot and observe well-weathered blocks of Onondaga with silicified fossils [bryozoan bafflestone].

STOP 5: Large outcrop of Edgecliff
On the east side of Route 32 note a large outcrop of Edgecliff which shows, for the first time on this southwest-northeast transect, typical coarse-grained Edgecliff lithology. This is the southernmost exposure of the crinoidal biosparites which are so characteristic of the Edgecliff Member.

STOP 6: Chert seams and massive joints
DO NOT COLLECT AT THIS STOP; IT IS ON PRIVATE PROPERTY AND THE OWNERS DO NOT WANT ANY SPECIMENS OR BLOCKS REMOVED!
This outcrop, on the Kaaterskill (AMNH Locality 3137; see Feldman, 1985), known as Quatawichna-ach, takes its name from the Indian "place where all the water goes in a hole" referring to the chert seams and massive joints which take the water underground as it passes through the limestone (Chadwick, 1944). A stratigraphic placement of upper Moorehouse is indicated by [1] shale chips in the adjacent woods (probably Bakoven, since it outcrops a short way downstream], [2] dark-weathering chert, and [3] faunal similarity with upper Moorehouse strata from the Leeds area, specifically, Platyceras dumosum and Atrypa "reticularis." The fauna here is moderately to well-silicified probably due to the diagenetic action of percolating groundwater through the numerous joints. At this locality Feldman (1980) recognized a highly diverse Atrypa-Coelospira-Nucleospira Community containing the following morphotypes:
[1] Orthotetacids, Schuchertella (broad, flat)
[2] Nucleospira, Athyris (smooth spiriferids)
[3] Schizophoria (unequally biconvex)
[4] Atrypa (with frills)
There is a great similarity here with Lenz's (1976) Lower Lochkovian Howellella-Protathyris Community from the northern Canadian Cordillera in which he found similar faunal elements in an offshore position. A similarity is also evident to Copper's (1966) biotope of primitive, abundant Atrypidae in which variably sized atrypids occur with spiriferids and schizophorids in fine-grained sandstones, siltstones and shales with thin limestone interfingerings.

STOP 7. The only known exposure of the Bakoven/Onondaga contact
Descend steep embankment to Kaaterskill Creek where the only known exposure of the Bakoven/Onondaga exists. Whereas Oliver (1956) considered the Onondaga/Bakoven contact to represent a minor break in deposition we believe that the contact is a disconformity, albeit a minor one in this part of the state, representing a time period during which rapid crustal subsidence, to a shallow or proximal basin depth position below storm wave base, resulted in stratification of the water column and dysaerobic bottom conditions. We found evidence of a more substantial disconformity in central New York, near Syracuse, where the Union Springs Shale (lateral equivalent of the Bakoven) truncates westwardly dipping Seneca strata. At that contact there exists a substantial bone bed with reworked (?) crinoids and brachiopods, and current-sorted fish spines and/or teeth.

STOP 8 : Overlooking Catskill Creek
Overlooking Catskill Creek, to the east, note the Schoharie/Onondaga contact, to the east of which the Onondaga lies in an (overturned?) thrust-faulted syncline. If time permits we will examine the typical Edgecliff lithology at the waterfalls where trilobites, corals, and brachiopods are evident.

E: STRUCTURE AND STRATIGRAPHY OF THE NORMANSKILL GROUP (EARLY MEDIAL ORDOVICIAN) WEST OF THE HUDSON RIVER, TOWN OF LLOYD, ULSTER COUNTY, NEW YORK
ROBERT W. CUNNINGHAM
Department of Geological Sciences
State University of New York
College at New Paltz
New Paltz, New York, 12561
The rocks of the Normanskill Group, formerly included in the Hudson River slates and shales are among the first studied rocks in North America. Notables such as W. W. Mather, Sir William Logan, and James Hall studied the rocks in the mid-Hudson area in the 1830's to 1860's. Because of the complex structure and repetitive stratigraphy of the Normanskill work has progressed slowly, with the most extensive and recent studies being done in the Albany, N.Y. and Quebec areas. In the Mid-Hudson, particularly in Ulster County, the Normanskill rocks have never been adequately mapped, despite extensive exposures along the Hudson River and in area highway and railroad cuts.
Recent fieldwork in the eastern part of the Town of Lloyd has resulted in several discoveries in the Normanskill Group. A relatively diverse shelly fauna has been found in a thick sequence of laminated strata tentatively dating these rocks as post-Austin Glen, but pre-Balmville in age, probably making these the youngest Normanskill rocks yet found. Outcroppings of lower Normanskill aspect (Mt. Merino Formation?), the first seen in this part of Ulster County, have been mapped around Blue Point. Four structural domains have been recognized on the basis of structural and lithologic criteria. Two of the domains apparently cross the Hudson River. Numerous folds and faults have been mapped, some of which show evidences of multiple deformation. Outcrops exposing thick stratigraphic sections have been measured for possible correlation, and excellent sedimentary structures noted in the Austin Glen Formation. Analysis of the data collected during this fieldwork can lead to a more comprehensive understanding of the age relations, sedimentology, stratigraphy, and styles of structural deformation.

E: STRUCTURE AND STRATIGRAPHY OF THE NORMANSKILL GROUP (EARLY MEDIAL ORDOVICIAN) WEST OF THE HUDSON RIVER, TOWN OF LLOYD, ULSTER COUNTY, NEW YORK

STOP 1. Near Mid-Hudson Bridge approach.
This road cut exposes rocks of middle to upper Austin Glen lithology, dipping about 45 degrees west. Thick beds of graywacke show massive bedding and thinner beds expose primary sedimentary structures such as flame structures, convoluted bedding, and cross-lamination. Cleavage dips less steeply than bedding indicating a possible downward facing structure. Looking south into the road cut for the Mid-Hudson Bridge, one can see the most complete section of Austin Glen strata yet measured (Krusansky, 1983, Manning, 1983). This section begins at a fault exposed near the final turn to the bridge, and continues with little interruption to the toll gate. It then continues in a railroad cut until it intersects the center of a N15°W trending syncline. This syncline plunges NE, and covers much of the area in domain 2 (figure 1). Strata from lower to upper Austin Glen is seen in this section.

STOP 2.Lower Austin Glen strata
This outcrop in the vicinity of Johnson Iorio Park contains lower Austin Glen strata. Both the north and south ends are quite deformed with a small reverse fault exposed at the north end, and an intense fault zone at the south end. Numerous graptolites have been found in rock fall near the Park entrance.

STOP 3 Blue Point.
This area consists largely of lower Normanskill strata - probably Mt. Merino Formation. This is the only known exposure of this rack type west of the Hudson River between Kingston and Newburgh. East of the Hudson it is more commonly exposed. This rock is a highly indurated, gray-green argillite with silty or cherty interbeds, and occasional pyrite layers. Gray to black shales are characteristic of the upper part of the formation. It is probably allochthonous with four thrust slices present locally, two on each side of the Hudson (figure 1). These outcrops constrict the river by about 30 per cent (pre-railroad width) accentuating the hardness of this material. The strata generally dip and young northwest except at the north end where it is overturned. It is highly sheared and folded making stratigraphy very difficult. Bedding can be traced by following the cherty or silty layers when the light is right. The southern part of the exposure is green argillite cored by a brown, dolomitic argillite forming an antiformal structure. The middle portion of the outcrop is primarily green argillite while the northern end contains sheared, gray to black shales known from the upper Mt. Merino. Graptolites are commonly found in these shales. To the northwest, the contact with the overlying Austin Glen Formation is probably at the north end of the outcrop where light gray, thin-bedded shales appear. A thin covered zone separates this strata from thick bedded graywackes with thin shales characteristic of the upper Austin Glen. This suggests a major fault trending southwest. The presence of other Mt. Merino outcrops directly across the river at Mine Point raises the question of whether the Hudson River is structurally controlled or whether it is a superposed stream. Circumstantial evidence here and to the north at Crum Elbow suggests that this is a superposed stream.

STOP 4.Typical upper Austin Glen lithology
This outcrop contains thick gray-wacke beds with thin shale interbeds typical of upper Austin Glen lithology. These beds dip northeast and are overturned. Cleavage dips gently southeast. The stream to the south may be a fault trace. If this is so, the fault may have reoriented this strata causing the shallow orientation of the cleavage.

STOP 5. Interbedded gray shales and graywackes
Interbedded gray shales and graywackes averaging 2 to 4 cm. in thickness with occasional calciferous or dolomitic, laminated siltstones comprise this outcrop. The rocks in the upper part of the outcrop dip northwest and may be separated from the lower part by a bedding plane fault. The lower strata dip generally northeast and are more deformed than those above. All strata appear to be overturned.

STOP 6.
Here the same lithology is exposed as in Stop 3 except many broken sections of thick graywacke are present in the shales due to tectonic disturbance. These beds are overturned and dip about 25 degrees to the east. Bedding plane slickensides are numerous and are aligned approximately east west.

STOP 7.
This section represents strata of middle to upper Austin Glen aspect with thin turbidites at the south end and thick graywackes at the north. These beds are highly deformed with the northern, more massive strata apparently dragged into folds along a fault at the north end. Another fault separates the thick graywackes from thin turbidites at the south end of the outcrop. The overall structure dips northeast with the beds dipping nearly 90 degrees at the south part of the section, decreasing to 40 degrees to the north, and then overturning and dipping 40 degrees southeast at the north end. This outcrop also contains curved tension gashes in the massive graywackes and disarticulated folds of thin graywacke in 'smeared' shales at the south. A thick graywacke surrounded by shales truncates abruptly near the south end. Just north of this outcrop, a tight drag fold of smaller dimensions is exposed.

STOP 8.
Medium to thick bedded graywackes are exposed here which are upright, dipping 15 degrees northeast. Higher on the hill, these beds increase in dip and are likely to be separated from those of Stop 6 by a fault in a stream bed.

This outcrop contains black shales with fragmented sandstone layers enrolled in the shales. This outcrop is highly disturbed. Relatively flat-lying beds appears to pin almost vertical graywackes to the hill, while thick shales show pinch and swell structure between graywacke layers. Tension gashes and "riedel shears" can be seen in this convoluted section.

This exposure of lower Austin Glen contains 1 to 2 cm. thick graywackes and shales. Pyritic graptolites can be found here. Tight folds have formed in this sheared strata with shale enveloped sandstone fragments indicating the degree of deformation. Strata dip northeast at the south end and northwest at the north end, while the cleavage dips east-southeast at a low angle.

This 1500 foot (460 m.) long section consists of lower to middle Austin Glen lithology south of the Poughkeepsie Railroad bridge, and upper Austin Glen north of the bridge. This area offers a good stratigraphic section to compare to that in the Mid-Hudson bridge approach (stop 1), and that seen in the railroad cut north of Crum Elbow (stop 27). Beds 1 to 4 cm. thick of alternating graywackes and shales predominate in the southern strata with well developed (ignore the graffiti) reclining, parasitic folds. These give way to thicker graywackes and shales just south of the bridge. Graptolites were found where a cut was made for cables which cross the Hudson River. Thick beds of graywacke dominate north of the bridge abutment. At the south end of the outcrop the beds dip northeast at 40 degrees, increasing to 53 degrees north of the bridge. This is part of the synclinal structure seen at Stop 1.

Highland Landing. This stop consists of middle to upper Austin Glen strata dipping N65E. A small reverse fault cuts this outcrop and a thrust runs along the upper part. Turbidites averaging 10 cm. in thickness dominate the southern half of this outcrop, while thick turbidites with thin shales constitute the northern part beds. Flute casts are visible an the undersides of some beds.

A shear zone formed in a failed fold hinge occurs at the south end of this stop. Rounded sandstone blocks enrolled in a shale matrix give good evidence of the shear couple at work here. This commonly happens in the hinges of the recumbent folds found in this area when the rock is stretched beyond its yield point dragging fragments of more competent strata into dismembered folds surrounded by shale. The rocks dip steeply northwest at the south end of the outcrop, but flatten considerably to the north. This is apparently middle Austin Glen lithology.

These thick graywackes with thin shale interbeds characteristic of the upper Austin Glen are overturned, dipping 85 degrees northeast. Convoluted beds and rill patterns show the effects of dewatering of the clay layers due to loading. Note the foliated shale clinging to the bottom of some graywacke beds. Sigmoidal tension gashes show orientation of compressive forces, although block rotation cannot be inferred here. A tight fold seen at the north end leads into another shear zone with fragmented graywackes in a shale matrix.

Here, middle to upper Austin Glen with turbidite beds vary from 3 to 7 m. thick with thin turbidites overlying them. Beds are steeply dipping (NW) with a northeast strike. Sedimentary convoluted beds can be seen at the south end.

This is a steeply dipping limb of a synclinal fold which plunges gently north-northwest. Complementary sets of tension gashes indicates direction of maximum compression. Sedimentary structures include rilled surfaces, cross-cutting tool marks, and to the north a 100 foot long by 60 foot (30 m. x 20 m.) high bed under-surface with large flute casts of bidirectional orientation. Shales are altered in color from black to orange, possibly due to incipient metamorphism. It is unfortunate that this as well as many other important geologic features have been painted over in the name of school spirit, young love, or personal identity. North of this outcrop is a tidal pool indicating the pre-railroad (1878) shoreline. Before the railroads were constructed the Hudson River shoreline was considerably more sinuous.

This outcrop contains more sedimentary structures such as convoluted bedding, parallel, horizontal tool marks and, to the north, curved tool marks. Structural indicators are fibrous calcite slickensides, and tension gashes whose sigma one direction appears to be perpendicular to that of the last stop. Here again, orange weathering shales are seen.

STOP 18. House on river, quarry.
This quarry supplied graywacke curbstones for New York City. Near the river these middle to upper Austin Glen graywackes and brown weathering gray shales are quite deformed. Overturned shales are pressed against thick upright turbidites which dip 40 to 75 degrees southwest. In the quarry the beds dip 60 to 70 degrees southeast.

This outcrop contains varying lithologies with thick graywackes underlain and overlain by thin turbidites. Similar sequences are seen at several other outcrops. The south end of this section is a shear zone with folded, dolomitic graywackes enrolled in a shale matrix. Toward the north a thick graywacke is encountered, truncated by a reverse fault forcing thin turbidites around it. Immediately beyond, a thick section of 1 to 3 cm. thick graywackes and shales are displaced by faults every few feet.

Thin turbidites form an antiformal structure. Deformation is similar in style to Stop 19. Here, brittle deformation has resulted in at least 4 steeply dipping, cross-cutting faults. These faults separate the strata into zones with different orientations. At the south end the rocks dip 70 degrees to the east. In the next zone they dip about 30 degrees northeast, then 40 degrees northwest. They then change to 5 degrees to the west, and finally at the north end dip 40 degrees southwest and seem to dissect a north plunging anticline. Numerous tension gashes are exposed at the south end of the structure.

This outcrop begins in thin gray shales and laminated siltstones striking slightly west of north and dipping 65 degrees northeast. Small scale folds are well developed as are joint sets. To the north thick graywackes predominate. Here the beds have rotated to N35E, exhibiting tension gashes. North of the outcrop is a broken zone probably representing a fault.

Following a shear zone at the south end, the cut exposes thick graywackes with dolomitic, laminated turbidites. These beds strike S80W, and dip 35 degrees northwest. This is the first of two outcrops with this anomalous orientation. These rocks probably form a thrust slice separate from the surrounding rocks. This is probably an upper Austin Glen lithology.

Here is a continuation of the lithology in Stop 22. Thick, massive graywackes contain many rip-up clasts of foliated shale. At the north end of the outcrop laminated, dolomitic sandstones underlie the thick graywacke beds. These rocks strike S85E and dip 23 degrees NE.

These beds are oriented N60E to N40E dipping 40 to 67 degrees NW. This assemblage of rocks is dominated by thin turbidites with 10 to 15 cm. thick shale interbeds. This cut shows very good cleavage development with refraction of cleavage into the graywackes. Cleavage is oriented at N42E by 85 degrees SE. At the north end these turbidites dive under thick graywackes which lay at N85W, dipping 55 degrees, increasing to 90 degrees at the north end.

This outcrop consists af a 7 m. band af (2 to 30 cm.) turbidites underlain and overlain by graywackes up to 5 m. thick in a section totalling 40 m. (Hayden, 1986). Insoluble residue studies of some af these shales have revealed up to 55 per cent CaCO3 by weight (Miller, 1986). This outcrop is extremely similar in lithology and cleavage orientation to those in an outcrop located across the Hudson River the Roosevelt estate, suggesting a continuation of structure across the river. The strata of the outcrop dip southeast at 15 degrees at the south end, flattens in the middle, then steepen to 25 degrees SE at the north end.

STOP 26. Crum Elbow.
Here the lithology contains middle Austin Glen with 2 to 15 cm. thick turbidites and occasional thick graywacke beds. Cleavage in this outcrop is N35E dipping 76 SE. Several small thrust faults cause the bedding to splay in several directions at the center of the outcrop. Toward the north end of the outcrop is a kink fold whose axis trends N35E, plunging 73 degrees SE. North of this are lower Austin Glen strata striking N25E, dipping 35 degrees SE. The open valley and stream to the north probably indicate a fault zone.

This road cut contains the best stratigraphic section of lower Austin Glen north of Highland. A fault zone at the south end of the cut is traceable for a couple miles to the south-southeast, and forms the boundary between domains 3 and 4 (figure 1). The north edge of this fault zone contains small drag folds along the last two faults in the fault zone. North of here the strata are overturned, dipping steeply to the east. Thin (1 to 3 cm), turbidites dominate the youngest part of the section, thick graywackes are common in the middle, and thin turbidites again dominate the north end with a few thick graywackes interspersed. Where outcrop on the east side of the tracks ends, another fault terminates the stratigraphic section. North of this are more complexly deformed rocks of the same type and age.

This cut begins at Mile Marker 76, continues for about 1000 feet (300 m.) and contains repeating, sometimes overturned sections of lower Austin Glen strata. These rocks strike about N25E dipping 74 degrees SE. These turbidites usually are 2 to 15 cm. thick. At the north end the graywackes and shales are highly disturbed with massive sigmoidal tension gashes, and en echelon phacoidal fragments of sandstone surrounded by a shale matrix. The stream is probably another fault trace.

This section is complexly deformed and folds plunge steeply northeast. Beds are alternately upright and overturned. At the south end the bedding is overturned, and forms an undulating, curved surface. Tension gashes are vertically oriented, with a number of en echelon sets exposed. In the middle of the section the beds are generally upright. Boudined calcite slickensides are exposed about in gray shale 12 feet up from the road. A massive tension gash oriented horizontally is over twenty feet long and may bend around the rock mass which it envelopes. At least three generations of vein filling can be identified including milky quartz, white calcite, and late clear calcite. The beds at the north end of this outcrop are overturned and are composed of gray shale and thick graywacke. Flattened flute casts are oriented in a near vertical position.

Here the uppermost Normanskill strata are seen for the first time. These are laminated siltstones and shales (usually less than one cm.) with occasional thicker graywacke layers. Here the beds are overturned, striking N8W and dipping 57 degrees NE. At the south end thick tension gashes are seen in the graywackes. Further north curvi-planar surfaces cut by joint sets are seen. These rocks seem almost 'reptilian' in appearance (curvi-planar with 'scales'). To the north, a thrust fault trace is exposed plunging moderately north. Massive tension gashes are exposed below, and up the cliff face they form large curving cavities. At the north end of the outcrop on the footwall of the fault the rocks are less deformed, although they still exhibit good jointing.

These rocks at Mile Marker 77 contain the same lithology as those in Stop 30; laminated siltstones and phyllitic shales showing good jointing. These beds are oriented N8E and dip 72 degrees SE. The strata, and most of those to the north and west continue for miles striking a few degrees east or west of north and dipping-steeply east for the most part.

These laminated siltstones, sandstones, and shales belong to the uppermost Normanskill strata. Bedding is variable as this location is near an inferred east-west fault zone. The Esopus fault lies about 3000 feet west of here. Fossil brachiopods are found in the disturbed rock, but the exotic trilobites found further south have not been seen here.

STOP 33. Railroad cut through north end of Illinois Mt.
Here the Esopus fault lies to the south with rocks of the upper Ordovician Quassaic Group sitting to the west. These rocks form most of Illinois Mountain, and then bending eastward to form the hill to the northeast. The unnamed rocks of uppermost Normanskill are laminated sandstones, siltstones, and shales. They are seen on the east end of Grand Avenue and along a power line running along the east side of Illinois Mountain. Numerous small brachiopods are found in these rocks. In the railroad cut rocks of the Slabsides Formation of the Quassaic Group are exposed. These are steeply dipping, medium to thick graywackes with thin shale interbeds. Shale clasts and limestone pebbles are much more common than in the Normanskill strata. Large strophomenid brachiopods are often seen on the bottoms of sandstone beds.

F: GEOLOGY ACROSS THE GREAT VALLEY:FROM THE SHAWANGUNKS TO THE HUDSON HIGHLANDS
Lawrence E. O'Brien
Orange County Community College
Middletown, New York 10940
Introduction
Orange County is a region of diverse geology, with bedrock ranging in age from Precambrian to Devonian, with structures ranging from klippe and overturned folds to relatively flat-lying strata, with geomorphic features varying from bedrock to glacial, and with fossils varying from the Otisville Eurypterid to the Sugarloaf Mastodon. Despite this diversity the county has not (with the exception of the Hudson Highland area) been the site of a great deal of geologic study.
On this field trip we will begin with the least deformed Silurian Bloomsburg and Shawangunk formations on the west side of the county near Port Jervis and traverse southeastward through succeedingly older and more deformed rocks of Ordovician and Cambrian age to the 1.1 billion year old Precambrian rocks of the Hudson Highlands following routes I-84 and 9W. We will not have time to see some of the interesting rocks and structures farther south along the New jersey border but these have been discussed by Offield (1967) and Jaffe and Jaffe (1973).

F: GEOLOGY ACROSS THE GREAT VALLEY:FROM THE SHAWANGUNKS TO THE HUDSON HIGHLANDS

Lower Devonian Esopus formation
The cliff behind you is the sands and shales Lower Devonian Esopus formation (sometimes called the Esopus Grits in this area).

Trilobite Ridge - Lower Devonian Glenerie Limestone
Between mile markers 1 and 2 the ridge visible to the left (north) side of the interstate is Trilobite Ridge, a famous collecting locality composed of the Lower Devonian Glenerie Limestone.

Silurian Bloomsburg Red Beds.
The redbeds on the right are the sands and shales of the Silurian Bloomsburg Red Beds.

STOP 1. Stop at the parking area.
The view northwest from this overlook is across the valley of the Neversink River which flows in a valley composed of Devonian carbonates (the Onondaga Limestone) lying between the Shawangunk Ridge (to the right) composed of middle Silurian clastics and Allegheny Front (across the valley), composed of Devonian clastic strata of the Hamilton Group. The confluence of the Delaware and Neversink Rivers is to the left in Port Jervis. The Delaware River can be seen to the southwest as it flows along the west side of the Shawangunk Ridge.
The rock cut to the west of this parking area is in the redbeds of the Silurian Bloomsburg Redbeds (or High Falls Formation) which strike approximately N.40°E and dip 25-30° NW at this location. They consist of fine red sands, silts and shales, often with mud cracks and gray reduction spots, interbedded with coarse, gray-green sands showing trough crossbedding. There are noticeable carbonate grains in the coarse cross-bedded sands. The Bloomsburg, which is conformable with the underlying Shawangunk conglomerate (stop 2), is inferred to be an alluvial deposit with the coarse beds reflecting channel deposits and the finer redbeds being floodplain deposits. It was shed westward from the mountains of the Taconic Orogeny, which existed to the east, into a sea which existed to the west. This formation grades downward into the basal Shawangunk conglomerate which unconformably overlies earlier (pre-Taconic Orogeny) sediments.
Things to look for at this stop include:
1. Good cross-bedding in the coarse gray sands.
2. Carbonate grains in the coarse gray sands (what is their origin?).
3. Gray reduction spots in the redbeds. Some vertical reduction spots may follow burrows.
4. Pebbles of fine red silts/shales in the coarse gray sands.
5. Mud cracks in the finer sediments.
6. Invertebrate tracks. I have seen these at one other locality, but not here.

STOP 2: Angular unconformity between Shawangunk and Martinsburg
This location is at the angular unconformity below the middle Silurian Shawangunk formation and the underlying mid-Ordovician Martinsburg formation. At this locality the angular discordance is very slight which is the same as I have seen at other exposures of the unconformity in Orange County.
The basal Shawangunk is a quartz-pebble conglomerate with a sandy matrix which grades upward into a coarse sand with fewer and smaller pebbles. Some feldspar fragments are visible in the upper coarse sand areas. The limonite stain on the Shawangunk results from oxidation of pyrite which may be seen as minute grains in the matrix of the conglomerate. The Shawangunk has been interpreted as a beach deposit (Fink and Schuberth, 1962) and as a braided stream deposit in a complex transitional marine-continental environment (Epstein and Epstein, 1972).
Between the Shawangunk and the Martinsburg is a brown clay layer which may be seen in other exposures of the unconformity in this area. Waines (Waines, Shyer and Rutstein, 1983) has speculated on the origin of this layer and has called it a paleosol, although there are several other plausible origins. The other possibilities will be discussed on the outcrop.
Walking around the outcrop to the right (west) you may note some glacial smoothing of the dip slope and along a trench behind the outcrop you can see an exposure of slickensides on a fault plane which strikes N 60° W and dips about 65°NE. The slickensides plunge about N 40° W at 30°. According to Fink and Schuberth (1962) tear faults like this are more common farther south in New Jersey. There are also several quartz veins on the dip slope and they strike N 70°±10°W.
Things to look for at this stop include:
1. The clay layer at the unconformity.
2. Pyrite grains in the Shawangunk.
3. Slickensides on the tear fault.
4. Glacial smoothing and quartz veins on the dip slope.
5. Variation in quartz pebble size and quantity. An interesting question is what is the source of the quartz pebbles since they are not common in the underlying Martinsburg.

Drainage interruption due to the highway.
The swamp in the median and to the right (south) is an example of drainage interruption due to the highway. A beaver lodge is sometimes visible in this swamp.

STOP 3: Approximate mile marker location 9.8
This is the first of four stops in the mid-Ordovician Martinsburg formation which will emphasize different types of structural deformation and sedimentary features.
At this location you can see more or less horizontal beds in the Martinsburg at each side of a section of almost vertical beds. The deformed structure is approximately 225 feet wide and varies from N 25° E, dip 82° SE on the south side of the highway to N 15 E and vertical on the north side. This seemingly isolated segment of almost vertical beds could be several things: an isoclinally folded anticline or syncline, a monocline downthrown to the northwest or to the southeast, a rotated fault block or possibly something else. The graywacke beds in the Martinsburg often show graded bedding so it is possible to determine the original bed tops in the vertical section. It appears the bed tops are all facing the northwest (thus eliminating the isoclinal fold possibility) and they show an obvious upward curvature at the west end of the tilted section. This suggests a monoclinal flexure downthrown to the northwest, but similar indications of folding at the southeast end of the tilted section are not apparent. I suspect the monocline has been cut off by faulting at the southeast end but the evidence is not clear.
A second question is when did the deformation occur. Conventional thought would relate it to the Taconic Orogeny of late Ordovician time, but Epstein and Lyttle (1986), based on work done in 15 areas along the Taconic Unconformity from Pennsylvania to New York, suggested that post-Taconic faulting had cut both the Martinsburg and the overlying Shawangunk. Compare this style of deformation with the other styles of deformation you will see in the Martinsburg at stops 4 and 6 and ask yourself whether this high-angle faulting might represent a different episode of faulting.
Things to look for at this stop include:
1. Grading in the graywacke beds.
2. Slickensides on the bedding planes of the vertical beds. Try to determine sense of motion of the slip.
3. Evidence for folding/faulting at the east end of the deformed section.

STOP 4. [Approximate mile marker location 11.3]
This cut is on the north side of the west-bound land of I-84 [Note: During the field conference this will be the first stop so that we will not have to cross the highway].
At this location the Martinsburg shows a typical "suddenness" of intense deformation. Beneath the overpass and to the east of the overpass the beds are relatively flat and seemingly undisturbed, but about 130 feet west of the overpass the bedding is sharply deformed by an overturned anticlinal fold which has been cut by a thrust fault. This thrust fault and associated drag folding extends 140 feet further west where it curves upward to the top of the road cut in a characteristic listric-fault fashion. The fault and associated drag folds strike about N.40°E and dip SE. Be sure to compare this style of deformation, which I consider to be unquestionably Taconic, with the style of deformation you see at Stops 3 and 6 in the Martinsburg.
This is a good location to examine slaty cleavage in the shale layers. It strikes N.40-60°E and dips 25° SE, but does not penetrate the graywacke layers. This is a good stop to show students that slaty cleavage is a pressure phenomena unrelated to primary bedding. The sketch at the left extends west from the overpass to the west end of the cut.
1. Slaty cleavage between the graywackes.
2. Synclines and overturned anticlines produced by drag folding.
3. The listric thrust fault. Try to estimate the amount of offset if you can find a suitable marker.

Underpass with wind generator to left (north).

STOP 5. Recent (1968?) deformation in the Martinsburg
This is a brief stop to examine recent (1968?) deformation in the Martinsburg. Notice the drill holes on the south side of the highway. They have been offset by slippage in an up-dip direction to the northwest. I was told by Cliff Lloyd, who brought this site to my attention, that most of this deformation took place shortly after completion of the highway and that for a time the highway department had been quite concerned about it. I have stopped here a number of times since 1973 and there has been no noticeable change since that time. You can see that there are several slippage planes, each deformed by a thrusting motion, probably related to stress relief following excavation of the road cut. For a recent article on this phenomena with a list of reference see Bell (1985). He lists references to other such features in the Appalachians.
Across the road you can see another thrust fault (Taconic) which strikes N20°E and dips 35° SE.
1. Amount of offset on the recent faults.
2. Drag-folding on the thrust fault.

Bridge over the Wallkill River.

Gravel flows on the right (south) side of the highway.
The gravel, intended to prevent slumping of the underlying material, has itself flowed downslope. These flows have noticeably enlarged over the past few years. Do you think the motion is partly within the gravel, or is it merely slipping over the substrate? Compare this with the cuts at 34.0 and 35.3.

STOP 6. [Approximate mile marker location 31.5]
This long road cut shows a number of interesting features, both structural and sedimentological, in the Martinsburg formation. The diagram at the left extends along the cut on the south side of the highway westward from the overpass for 500 feet.
Structure: On the south side of the highway there are a number of faults which cut the strata. Examination of the drag folds and the offset of the strata at 200 feet show that these are mainly normal faults. This deformation does not seem to match the thrusting which was evident at stops 4 and 5. While it would be nice to see a normal fault offsetting a thrust fault, I nevertheless believe this is a post-Taconic period of faulting. Whether these faults, downthrown to the southeast, are related to the deformation at stop 3 (downthrown to the northwest) I can't tell.
North of the highway and east of the overpass are a pair of adjacent anticlines offset by a fault, and plunging in opposite directions. This in an interesting spot to have students test their powers of observation.
Sediments: The Martinsburg is a classic flysch deposit with the graywackes of the Martinsburg being classic turbidites (turbidity current deposits) (McBride, 1962). Turbidites are considered to have an "ideal" sequence of structures which has been called a Bouma cycle after the Dutch sedimentologist who described them in 1962. A complete Bouma cycle consists of the five divisions shown in the diagram below. Often some of the divisions are missing but the ones that are present are always in the same order. Proximal deposits (near their origin point) are more likely to have a significant A division whereas more distal deposits may consist only of divisions C, D, and E. Examine the graywacke beds closely and try to identify the various divisions of the Bouma cycle. Are these proximal or distal deposits?
1. Faults. What type? Amount of offset.
2. Drag folds along faults.
3. Oppositely plunging anticlines on north side of the highway.
4. Bouma cycles in the graywackes. Identify each division present. Are the turbidites proximal or distal?

Another long outcrop of Martinsburg.

Slumping in road cut to right.
This cut was given no special engineering protection to prevent mass wasting. Compare this with the cuts at 27.0 and 35.3.

Gravel drainage zone around top of road cut to right.
Highway engineers apparently decided to intercept the water which would percolate down the slope and cause mass wasting and drain the water off to the side. The lack of slumping or flow compared to cuts at 27.0 and 33.0 suggests it was effective.

STOP 7. This is one of perhaps 14 small (?) klippe
This is one of perhaps 14 small (?) klippe, or allochthonous blocks of Precambrian Hudson Highlands material which was thrust northwestward during the Taconic Orogeny and then isolated from the parent mass by later erosion (other interpretations have been made but this is the one I like).
Toward the east end of the road cut you can see the Cambrian age Poughquag Quartzite, which at this location is noticeably conglomeratic. The pebbles are mainly quartz and the matrix contains substantial amounts of pyrite. Oxidation of the pyrite has caused the pervasive limonite staining of the rock. Toward the western end of the cut the Poughquag overlies Precambrian granitic gneisses in a classic nonconformity. The gneisses have been severely weathered and are almost unrecognizable at the first casual glance. The attitude of the unconformity shows that the Poughquag extended above the level of the cut on the north side of the highway and has been eroded away so that only gneissic material is exposed. This transgressive Cambrian sand marks the inundation of the continent following rifting of the continent after the Precambrian Grenville Orogeny. It probably represents a beach environment.
The outcrop across the entrance ramp to the northwest (onto I -84 west) is Martinsburg, so the basal fault below this thrust block must be located between the two cuts north of the highway, however I have never seen reference to it by anyone who noted it during the building of the highway.
1. The non-conformity at the base of the Poughquag.
2. The granitic gneiss below the unconformity.
3. Variations in pebble content in the Poughquag.
4. Evidence for faulting in the Poughquag.
5. Pyrite in the matrix of the Poughquag.

Road cut though Cambro-Ordovician age Wappinger Group Dolomites.
These represent a stable shelf environment which existed here following the transgression of the Poughquag. They persisted until the downwarping of the continental margin began during the subduction and closing of Iapetus which preceded the Taconic Orogeny. They are overlain by the flysch deposits of the Martinsburg which are subduction-related (Isachsen, 1980). For additional information on these carbonates see Friedman (1975).

Start of oil tank area for Port of Newburgh on the left.
Several of the homeowners in the area complained of devaluation of their property as this tank farm expanded. Would you agree?

Bridge over Moodna Creek.

The hill in front of you marks the beginning of the Hudson Highlands.
The road leaves the valley of Martinsburg sediments, crosses the northwest border fault of the Highlands thrust block and starts up the Precambrian gneissic material. The first outcrop is visible on the left shortly after you start up the hill.

STOP 8: Overlook at Storm King.
[Note: During the field conference this will follow stop 9 so that we will be able to park at the overlook.]
This cut is an excellent exposure of the Storm King granite gneiss, at this location a two-feldspar, hornblende granite gneiss. The gneissic structure is shown by lineation of the amphiboles and a similar elongation of the quartz (Lowe, 1958. indicates there is "no clearly preferred space-lattice orientation" of the quartz). There are a number of pegmatitic zones in the granite and these have a similar mineralogy to the surrounding finer-grained areas. The pegmatite zones sometimes follow the strike of the lineation in the gneiss and at times cut across the lineation suggesting they are either late-phase crystallization or later remobilization of the material. The Storm King was first thought to be a late intrusion into the gneisses (Lowe, 1958) but is now suggested to be an early Grenville intrusion (Helenek and Mose, 1984, give a date of 1140 m.y.).
The overlook to the east provides an impressive view over the Hudson River.
1. Large hornblende crystals in the pegmatitic zones.
2. Orientation of the pegmatitic zones relative to the lineation of the gneiss.
3. Nature of the lineation.
4. A cross-cutting, epidote-filled fracture.
5. View from the overlook.

The proposed Storm King pumped storage reservoir site is on the right (west) side of the highway.

STOP 9. Other gneisses of Hudson Highlands and a nice dike
This cut exposes some of the "other" gneisses of the Hudson Highlands, and one of the best dikes you could ask for.
The gneisses are quite varied in composition and in several places show coarse-grained remobilized zones. Garnets are abundant locally but they are usually fractured and are difficult to remove from the gneiss. You can see how distinct the Storm King gneiss is from these other gneisses.
The dike, which is visible on both sides of the road cut, strikes across the road cut at N47°E and dips approximately 70°NW but it curves markedly on the right (east) side of the cut. Close examination of the dike shows it to be mafic (dioritic to gabbroic) with accessory pyrite. There are excellent chilled margins with knife-edge sharp contacts with the country rock (best seen on the east side of the cut). There are also several apophyses (tongues) extending into the country rock. About 2 meters above road level on the east side of the cut, you can see two small light-colored intrusions into the chilled margin of the dike. These obviously came from the dike's still molten interior and thus are auto-intrusions, one of the clearest examples I have ever seen.
Facing the dike on the east side of the cut, you should notice the dark (mafic) band about 7 cm wide which parallels the right contact inside the chill margin. This mafic zone does not exist along the left contact but there is visible a zone parallel to the contact and inside the chilled margin characterized by coarse blebs of light and dark minerals. Similar zones are visible in the dike on the other side of the cut but they are harder to see because of groundwater which normally drains along the margins on that side. These dissimilar zones present a problem. Why is the dike not symmetrical? I am tempted to believe the mafic zone on the right is an example of crystal settling of the mafics and the blebby zone on the left represents the last stages of crystallization of the dike, but if this is true it would seem to require a significant upward rotation of the dike since its crystallization. I have not seen or read of a similar feature on other dikes in the area (Mack, 1962; Ratcliffe et al, 1983; and others). Differential weathering is noticeable at the top of the dike where the spheroidal weathering of the mafic dike is in sharp contrast to the minimal weathering of the surrounding gneisses.
The engineering techniques used to minimize the hazard of falling rocks are also worth mentioning. On the west side of the cut you can see rock bolts, a ledge and a fence (chicken-wire conglomerate). What you can't see is that they have replaced the guard rail on that side 3 times in the past 15 years and still there are dents visible on top of the rail. The fault zone visible above the ledge was the source of a major fall several years ago. A fracture pattern on that side of the cut dips into the cut so it is virtually impossible to totally prevent rock falls here.
1. Intrusive features such as chill margins on the dike, auto-intrusions in the dike, and apophyses from the dike.
2. Mafic and blebby zones in the dike.
3. Spheroidal weathering at the top of the dike.
4. Remobilized zones and garnets in the gneisses.
5. Evidence of falling rocks and engineering techniques to prevent them.

G: KARST AND STREAM CONSIDERATIONS IN THE ENVIRONMENTAL GEOLOGY OF THE MIDDLE RONDOUT AND ESOPUS VALLEYS, ULSTER COUNTY, NEW YORK
Lawrence R. Matson
Department of Physical Science/Geology
Ulster County Community College
Stone Ridge, New York 12484
The geology of the middle Rondout and Esopus Valleys is as rich and varied as is the story of the struggle of the early colonial Dutch, French and English settlers of this region. The area has remained essentially rural in character until recently, but with the relative nearness of the nation's largest metropolis in the time of rapid transportation and high-tech employment the region's land is quickly becoming developed.
Soils in these valleys are on bedrock of carbonates topped by thick deposits of till, modern alluvium and post-glacial lake bottom deposits. These valleys are well known for abundant harvests of sweet corn and apple production. Any acid precipitation is apparently neutralized by the carbonate character of the bedrock and the alkalinity of the streams that flow across them since no noticeable effects that occurred in these valleys. But the increase of population is coupled with a greater need for groundwater construction resources such as sand and gravel, and additional land fill sites for waste disposal. Land development has occurred here, as it has in many other areas, with little forethought and planning for environmental consequences. This field trip is a look at some factors that should be considered here and in other areas with a similar projected development of the land.
Figure 1 is a location map for this field trip. The trip can be taken with 11 stops or as either of its parts. The first part, trip G-I (stops 1-6) is a study of the environmental geology and hazards associated with Karst features of the Stone Ridge area; and the second part, trip G-II (stops 7-11) is a study of the environmental geology of the Esopus Creek Valley and some factors that may be at least partially responsible for apparently increased stream flooding and the resulting publicly voiced concern of local residents.
The middle Rondout and Esopus Valleys are enclosed by clastic rocks of the Shawangunk Mountains to the southeast and the Catskill Mountains to the West. A more complete discussion of the bedrock geology of this "classic" area has been recently described by Lindemann and Waines (1987), and a postulated stratigraphic column of most of the formations of the valley is given in Figure 2. The Onondaga Formation is located stratigraphically 225-420 feet higher in the column than the Glenerie Formation. The basal Onondaga Formation beds are coarse-grained limestones containing abundant corals and large crinoid columnals, while the upper beds are fine-grained limestones containing dark-gray to black chert and bryozoa and brachiopod fauna.
Karst features of the Stone Ridge, N.Y. area involve principally the Onondaga, Becraft and Rondout Formations, all quite pure limestones subject to dissolution. These units have been mined in open pits and shafts for the manufacture of natural and portland cement and for use as construction aggregate. A small solution cavity swallowing an intermittent stream is located in the Onondaga Limestone near the intersection of Route 9W and Route 199 near Kingston, N.Y. and outside of this field trip area. Pre-Wisconsinan near-surface weathering may have led to the development of solution features along joint planes in the carbonates of these valleys.
Concurrent with the forced closings of present landfills throughout the region, community leaders are faced with the difficult tasks of locating economically feasible waste disposal sites while also protecting their citizens, present and future. In order to locate and determine sites that are suitable for safe waste disposal, knowledge of site geology must be included. Early input by geologists and hydrogeologists may quickly rule out some areas before costly engineering and construction is performed. Conversely early study by geologists and hydrogeologists may affirm the inherent suitability of a site and allow progress in the difficult task of landfill selection. Important in the study of landfill site selection, in the proper management of sand, gravel and water resources and in stream flood control is an appreciation of the surficial deposits. The surficial deposits of the study area include lodgement till, modern alluvium and kames, (figure 3).
Figure 4 is the location map for a proposed landfill site near Rest Plaus Road in the Town of Marbletown. The geology and hydrology of the site and nearby areas proved to be more complex than could be estimated from published geologic maps and a brief study would indicate. Field trip part G-I examines the evidence that geological and hydrological data should be gathered and analyzed early in landfill site selection.
Field trip part G-II is a study of stream conditions that have become, at least in the eyes of the public, an increasing threat from flooding. The Esopus Creek has, however changed its course several times in the pre-history and perhaps early history of the area. With this fact in mind, present land-use practices may be evaluated less harshly than may immediately be apparent. Nevertheless, certain land-use practices, such as mining or other stream disturbances may upset a balance and increase existing environmental problems. We will examine the possible or probable effects of mining, agriculture, and residential and commercial development in the Esopus Creek floodplain.

G: KARST AND STREAM CONSIDERATIONS IN THE ENVIRONMENTAL GEOLOGY OF THE MIDDLE RONDOUT AND ESOPUS VALLEYS, ULSTER COUNTY, NEW YORK

Oxbow on right (west), and Stop 10.

Bridge over Esopus Creek.

Onondaga Limestone exposed along highway for next 1.5 miles.

Meander of Esopus Creek on right (west).

Onondaga Limestone (old quarry?) on right (west)

STOP 1. Enlarging Sinkhole
This sinkhole was first noted in the mid- 1970's. At that time, it was approximately 5 feet in diameter and provided a convenient drain for the then-producing grapevines nearby. In ten years, it has enlarged to its present diameter of about 20 feet, with two well-developed channels leading to it. A drain next to the highway leads to a storage basin that overflows with each heavy rain. CAUTION PLEASE: the storage basin cover is a lightweight steel plate and is usually lifted off the basin entrance by the force of the overflowing water; the opening is a danger to anyone walking through the brush along this road.
Another small sink has developed next to the foundation of the rear of the two-century-old house immediately north of this stop. Please respect private property and do not enter without permission. An additional sink is located east of the rear lawn, and some subsidence is in evidence on the front and side lawns.
The former owner of the property on the west side of the highway wished to construct a small pond on the property. He excavated soil and lined it with clay as he was instructed by personnel with the State Department of Environmental Conservation, and watched it fill with rain water. He was quite perturbed to see the water go "down the drain." In the center of the dry basin was a hole about one foot in diameter which he sealed with cement. The man-made basin stays dry and the present landowners are evidently trying to fill it with debris.
The cause of the sinkhole development here is evidently the collapse of a cave or cave system within the Onondaga Limestone during a lowering of the local water table. When the water level dropped, the cave roof was unsupported and collapsed. The condition is accelerated by the entrance of surface water that can cause more solution of the carbonate bedrock.
In the mid-1970's, a company located about one mile to the north of this site was using water drawn from several drilled wells. The company reportedly had a need for a dependable and plentiful supply of water and were concerned that the water level in its wells had dropped more than 40 feet in three or four years. The company wanted to know where it should drill for more water. At least one neighbor was concerned that the company's drilling for more water was causing his household well to be contaminated with silt and clays. The company was advised to obtain its water from the west side of the highway from tills and alluvial sediments in the Esopus Valley. This "solution" has evidently ended for the present the company's water supply problems.
The cause for the lowering of the local water table is difficult to determine. The construction of the wider highway may have restricted important recharge locally (Egernier, personal communication). Ulster County Community College with large, impermeable parking lots and increased commercial development locally may all be withdrawing much water and preventing recharge that could result in a lowering of the water table. There has been a significant increase in the number of homes built nearby, and all have drilled wells with cones of depression that may cause a lowered water table. The temperature-precipitation conditions may have changed to decrease the ground water recharge. A stream, local excavation, or roadcut nearby may have intersected a cave or fracture system that is now flowing as a spring. Of course, the lowering may be a natural event producing a sinkhole that should be considered normal in a carbonate bedrock located in a humid region. Well-developed sinkholes that are located at Stop 2 have evidently formed naturally during the past.

STOP 2. Hendricks Lane Sinkholes
Positions of at least four sinkholes can be seen in the field to the south. They can be recognized by stands of large trees. Farmers were not able to work the land at sinkholes and trees were allowed to grow there. A sinkhole in the field to the north was covered during the early 1980's. It will be interesting to see how long it will remain covered and tillable.

Limestones in roadcut
Limestones in roadcut, former railroad overpass at hamlet of High Falls.

Rondout Creek meander on left.

Limestone on right, New Scotland and Kalkberg Formations.

STOP 3. Pompey' s Cave
A suggested explanation of the initiation of this cave and subsurface drainage follows. Kripplebush Creek has cut through a recessional moraine at the hamlet of Kripplebush and its course meanders considerably as it flows southeasterly across the post-glacial lake bottom deposits and empties into the Rondout Creek nearby. The Rondout Creek flows over a shrinking waterfall ~2 miles north at High Falls since the caprock is dipping west. As the waterfall height lowers and as the Rondout Creek above the waterfall continued to erode through the carbonates, the base level of the Kripplebush Creek was lowered and the local water table dropped. Subsequently, the lower reach of the Kripplebush Creek was rejuvenated and has cut into the Rondout carbonates. The water evacuated from the cave beneath the Mg-Carbonate member of the Rondout Formation following the lowering water table, and eventually the surface stream began seeping downward through and, thereby, enlarging joints in the Rondout carbonates. This probably occurred first in joints near the Rondout Creek, then later in joints farther upstream. Now, the stream enters several "swallow holes" upstream and has become an underground stream flowing presumably into the Roundout Creek. Indications are that this process will continue and, in fact, the upstream, meandering portion of the stream seems to be rejuvenated more each year; it is expected that the increased downcutting will result in additional sinks developing in the stream bed as long as the surface water can enter a cave below it.
Note the character of the dry stream bed near the Lucas Turnpike bridge. Joints are apparent, and well-developed mudcracks can be observed. An entrance to the cave is located a few hundred feet "upstream" in the dry stream bed, and a homemade ladder is constructed to assist people who wish to enter the cave. CAUTION: The property owner has not chosen to "post" or restrict valid study of this local phenomenon. If you decide to enter, please realize it is your decision and you have decided to assume any associated risk. Before studying or entering the cave, you may wish to walk upstream farther to see a partial collapse of the stream bed into the cave below, and to observe the stream entrance holes farther upstream. CAUTION: The fields nearby are used for pasture for cattle. Be careful that a bull in not loose nearby or you may need to make a hasty retreat downstream! If you decide to enter the cave, check each ladder rung very carefully to determine if it will hold your weight. Always leave at least one person on the surface to obtain help if the ladder breaks.

STOP 4. Rondout Creek Meander
This vantage point provides an excellent view of the Rondout Creek at a magnificent sweeping mobile meander. During flood stage, the stream severely undercuts its bank and some slumps and subsidence have occurred.

STOP 5. Artesian Spring and Pool
A fence protects an unwary visitor from the artesian spring (locally called a sinkhole) located near the western boundary of the RMC parking lot. This is reported to be the third protective fence placed around this feature, following the enlargement of the pool and loss of the fences. This lot was a sand and gravel quarry that was mined until the operators noted the appearance of groundwater surfacing. After mining ceased, the property was developed in the 1970's as the current operation. Water broke through the sand forming an apparent sinkhole. Evidently, sand is flushed out and onto the land surface with occasional increased water flow, causing a pit to form filled with water. The pool within this pit was plumbed to be about 40 feet deep in the early 1980's. I have observed water, and possibly gas bubbles, ejected one or two feet into the air, with the appearance of "rising" and/or "jumping" fish! The. aquifer feeding this spring is unknown and somewhat of an enigma, since the elevation of discharge is about 30 feet higher than the nearby unnamed stream. The surrounding surface is generally at a lower elevation and increased discharge does not seem to be immediately correlated with rainstorms. No geochemical tests of the water or continuous studies or monitoring of discharge are known. Could this spring be the outflow of a leak in the nearby Rondout Pressure Tunnel section of the New York City Aqueduct? Clearly, additional study is warranted and could prove interesting. In any event, it does indicate that the hydrology of this area is not well-known.

Narrow former underpass of former railroad.
The rocks used in constructing this underpass/railroad bridge foundation were taken from the old Delaware and Hudson Canal works

STOP 6. Rest Plaus Road Proposed Landfill Site
This site was considered as a landfill for the Town of Marbletown in the early 1980's. The landfill would be located within the shielding forest to the northeast with a leachate lagoon located on the southwest. The soils of the land on the western portion of the property would serve as the mine for the daily landfill cover, as well as to provide for some future expansion of the landfill if needed.
Near the southern boundary of the property, a small stand of trees can be seen from the road in the field. Close examination shows that the trees are growing within and around a shallow, filled sinkhole. Blocks of the relatively soluble Becraft Limestone are exposed, and dissolution has occurred between the separated limestone blocks which are at slightly different attitudes. Some surface runoff is passing into this depression. At various depths, Becraft Limestone and other limestones less susceptible to solution and sinkhole development underlie the proposed lagoon and landfill areas, as well as the proposed landfill nine.
Some less obvious solution effects can be observed along joint planes and limestone nodule layers in the Port Ewen mudstones. These appear to occur within 2 m. (~ 6ft.) of the bedrock surface and can be seen after a short walk along the abandoned railroad grade along the east border of the site.
In addition to solution effects calling into question the use of the site as a landfill, there is some evidence that a southeast-northwest thrust in the Port Ewen Formation occurs in the eastern limb of a northeast-trending plunging syncline, projected along the hillside and crossing the abandoned railroad grade. Also, a much smaller, narrower, more tightly folded, northeast-trending and plunging anticline may project into the southern half of the property and may pass through the location of the previously described sinkhole in the Becraft Limestone.
Clearly, additional geology and hydrology investigations are called for before this property should be used as a landfill. The recent search for a town landfill has been abandoned, and there are at present no known plans to determine the suitability of this site.

East overview of Stop 6, former proposed landfill site.

STOP 7. Esopus Creek - "Bathtub"
This area is called locally the Bathtub. Reportedly, sand and gravel mining was conducted here, along the outside of a stream meander. During a flood in the 1960's, the stream cut through the narrow berm separating the quarry from the stream, and the quarry became a portion of the stream. Mining operations have been relocated to several other areas of the Esopus Floodplain; we will visit some of the newer operations.
Environmental problems associated with a breach of quarry operations that could affect the Esopus Creek include the following. (1) The stream slows when entering the wider, deeper area, and exposure to additional light coupled with less shade from protective shoreline trees will warm the waters. The warming waters will be expected to hold less dissolved oxygen and the stream ecology will, thus, change. This renowned fishing stream will probably produce fewer trout in the future. (2) More rapid stream bank erosion may be expected during flood stage causing an increase in stream sediment load. This also is expected to change the stream ecology. (3) Increased erosion here should produce increased stream channel deposition downstream, and more overbank flooding more often. Communities downstream include the hamlet of Hurley, the City of Kingston, the hamlet of Lake Katrine, the Town of Ulster, and the Village of Saugerties; increasing concern is being expressed in local newspapers by citizens and local government officials (Kwiatoski byline, Kingston Daily Freeman, 10/2/87 and 10/5/87). The usual call is for the Army Corps of Engineers to dredge, channelize, or to otherwise provide increased flood control of the middle Esopus Creek.

STOP 8. Town of Marbletown Park, Esopus Creek
A kame can be seen to the south that has been mined since the late 1970's. A kame is valuable for sand and gravel mining, since it is sorted by glacial-fluvial processes and operations can thereby save considerably.
The Esopus Creek enters the valley about one-half mile upstream (west) of this stop and begins a broad meander to flow northeasterly. Mining of sand and gravel deposits was done on the floodplain on the opposite side of the stream, evidently in accordance with (then) existing state and local regulations that required a minimum 10-foot berm to be left untouched. Floods of the late 1970's repeatedly breached the berm; and repeated efforts to reinforce the berm with at first gravels and then a steel wall continually failed. Rapid bank erosion has begun on the south side of the Esopus. In 1977, a row of trees about 20 feet wide existed from the man-made sand beach to the east along the creek. These have been washed away. The channel downstream is evidently filling with gravels, and it appears the stream may be changing its course here because of, or in spite of, the mining disturbance.

On left, is this a meander scar of an earlier Esopus Creek channel?

Is this an oxbow of an early Esopus Creek?
This was a nearly filled pond until the 1980's, when it was dredged to provide a more attractive pond. It is possible that the stone house was constructed alongside a well-flowing stream two or three centuries ago. Several small streams flowing into the valley seem to flow into meander scars of a once larger stream. Of course, they may have constructed these meanders themselves if they previously had a greater discharge. However, several other undoubtedly Esopus Creek oxbows and meander scars are apparent from a study of the Kingston West Quad.

Sand and gravel mining on right side
Operation has been intermittent during the 1980's.

STOP 9. Fording Place on Esopus Creek.
Sand and gravel mining can be studied here. Note that an operation in modern alluvium, ground moraine, and lake deposits must include mechanical separation or grading. This increases mining costs to the operators. Occasional glacially carried boulders and cobbles can be found here, recognized by facets and striae. Note also that the operations of the mine are near the stream and the berm is occasionally breached by floods. When water is low, many local residents ford the stream here with their vehicles. The hamlet of Marbletown is located on the other side.

Fallen rock zone; cliff prone to landslides.
This valley wall was probably cut by the glacier(s), but the cliff base may have also been undercut by an early meandering Esopus Creek.

Landslide prone area.
Rockslides and slumps occur here about every 7 to 15 years, often covering the roadway. The highway department has each time quickly removed the supporting talus at the base of the cliff, probably encouraging additional future landslides. Note the "blocks" of rock (Hamilton Formation, shales and siltstones) that are ready to break loose along joints.

Crossing over a meander scar of early Esopus Creek?
At the end of Evergreen Lane, a broad, open oxbow lake, a meander of an early Esopus Creek can be seen (on private property). This oxbow lake is apparent on the Kingston West Quad.

Lawns on left were damaged in 1987
Lawns of the houses on the left were severely damaged by Esopus Creek floodwaters during the heavy rains of mid-April, 1987. If the rains had occurred with a melting snow, the damage might have been more serious. Large "potholes" or "swirl-holes" over 10 feet in diameter, several feet deep, developed in at least one lawn. The damage has since been repaired by residents.

STOP 10. Oxbow Lake
A large gravel-covered area on the right side of the road provides ample parking space. If you cross the road, use extreme caution since cars are leaving a controlled-access four-lane highway here and are often travelling at a high speed.
Some area residents believe that the stream's channel was changed by man during the construction of this newer section of Route 209, and that the pond along the west side of the highway was where the pre-highway Esopus Creek was flowing. The 1942 Kingston West Quad, however, shows that this existed before the highway was constructed in the early 1960's. It is certain evidence that the Esopus Creek has changed its course in the past, and probably will continue to do so in the future barring complete channelization.
This oxbow is undergoing rapid eutrophication now, since the nearby agricultural fields are heavily fertilized; normal runoff is feeding the vegetation within this oxbow.

STOP 11. Plaza Flood Control Project
Flooding during January thaws and spring melts of 1976-1978 caused citizens, commercial interests, and politicians to request the Army Corps of Engineers to provide flood control. The Corps of Engineers at first suggested that flood control might not be wise since it might cause increased flood problems downstream (north), but a compromise was agreed upon to construct flood control on the Plaza side only. High waters are now not a hazard to the stores, but some people have wondered if flooding of the opposite side might become more common now that nearly all the flood waters must flood onto the opposite side.

Continue driving along the flood control dike.
Note that high flow water can be diverted to a confined wetland to allow some groundwater recharge. Exit the Kingston Plaza and turn right onto Schwenk Drive. Turn right (north) at traffic light onto Washington Avenue.

H: GENERAL STRUCTURE AND ORDOVICIAN STRATIGRAPHY FROM THE
MARLBORO MOUNTAIN OUTLIER TO THE SHAWANGUNK CUESTA, ULSTER COUNTY, NEW YORK
MICHAEL J. KALAKA
1184 Ocean Avenue, Sea Bright, New Jersey, 07760
RUSSELL H. WAINES
Department of Geological Sciences
State University of New York
College at New Paltz
New Paltz, New York 12561
The Lower Wallkill Valley lies within the western portion of the Appalachian fold belt and is approximately 70 miles (43.5 km) northwest of New York City (fig. 1).
Within the study area the eastern side of the valley is flanked by Ordovician flysch deposits forming the Marlboro Syncline (Waines, 1986). On the western side is the Shawanqunk Mountain escarpment capped by the Upper Silurian Shawanqunk Conglomerate.
The Middle to Late Ordovician Martinsburg Formation forms the bedrock of most of the Lower Wallkill Valley while the bedrock on the eastern side is underlain by Middle to Late Ordovician Quassaic arenites. Most of this is usually blanketed by Wisconsinan till or alluvial deposits derived from the Wallkill River (Connally and Sirkin, 1967).
Because of structural complexities, infrequent fossils, and lack of stratigraphic markers it is difficult to establish close lithologic correlation within the Martinsburg Formation.
Previous attempts to determine and depict the structure and stratigraphy of the area by Holzwasser (1926), Rickard(1973), and Waines et al. (1983) have not been entirely successful. An increase in bedrock exposures as a result of recent road construction together with geologic data acquired from the Delaware West Branch Aqueduct (City of New York Board of Water Supply, 1938, 1939), Catskill Aqueduct (Board of Water Supply, 1905- 1918), and logs from three wild cat wells (Susi, Modena, Minnewaska) have enabled the construction of a composite northeast-southwest structure section (Kalaka, 1985, fig. 23). This section extends from the center of the Marlboro Mountains near Lloyd, New York westward through the Martinsburg Formation in the eastern central, central, and western portions of the valley continuing under the Shawangunk Mountains almost to Wawarsing, New York (figs. 2 and 3).
The section reveals three major structural domains (east to west) : (1) a monoclinal, southeast-dipping domain in which an arenite facies shales to the west and southwest (west limb of the Marlboro Syncline); (2) a complex domain involving mostly shales (central portion of the Wallkill Valley); (3) an open fold domain involving mostly shales (western portion just east of and under the Shawangunk Cuesta) (Kalaka, 1985, fig. 24), (fig. 2).

H: GENERAL STRUCTURE AND ORDOVICIAN STRATIGRAPHY FROM THE
MARLBORO MOUNTAIN OUTLIER TO THE SHAWANGUNK CUESTA, ULSTER COUNTY, NEW YORK

Allochthonous Normanskill on the east side of the Esopus Thrust.
Shale near telephone pole on left side of road is probably allochthonous Normanskill on the east side of the Esopus Thrust.

Crossing buried Esopus Thrust.

STOP 1. Here we are in middle third of Chodikee Formation
Here we are in middle third of Chodikee Formation (Strater, 1983) the uppermost unit of the Quassaic Group. We are located in the east limb of the Marlboro Syncline. The age of these autochthonous strata is Late Ordovician. Beds are vertical to slightly overturned to the west.

Bridge over Black Creek
Bridge over Black Creek fault where east limb of Marlboro Syncline has thrust westward over west limb of syncline.

STOP 2. Here is a more shaley version of the Chodikee Formation.
Fossils include brachiopods and highly deformed cryptolithids. Strata typically dip east.

Arenitic formations are shaling out to the southwest.
We will be moving down section for the next 2.1 miles and the normally arenitic formations in the Quassaic beneath the Chodikee are shaling out to the southwest.

Outcrop of Slabside Formation (?) on right.

Shaupeneak or Rifton Formation in road cut.
This is the last exposure in the east-dipping domain on NY 299.

Entering eastern margin of complex domain.

STOP 3. Here is a typical example of complex domain strata
Here is a typical example of complex domain strata in the road cut on the north side with a good east-west sectional view. The strata are Medial Ordovician Bushkill shales and siltstones.

Bushkill outcrop on left.

STOP 4. Deformed shales and siltstones with east-dipping cleavage.
Here, beneath the poison ivy, are deformed shales and siltstones with east-dipping cleavage. Again, these appear to be Bushkill and the exposure occurs near the center of the complex domain.

Head west across Wallkill River floodplain.
Cross bridge over Wallkill River and head west across Wallkill River floodplain.

View of Shawangunk Cuesta at 12 o'clock.

Roadcuts observed over next 2.6 miles are in the complex domain.

STOP 5. Extensive outcrop occurs at base of hill along river.
Predominantly east-dipping argillites are involved in some folding and faulting. A foundation of an old covered bridge is observable. Here is another aspect of the complex domain. The strata are apparently Bushkill. No fossils have been found.

STOP 6. This is a hiking stop
This is a hiking stop and we have been given special permission by the owner of the mill to walk across the property along the north bank of the Shawangunk Kill. Please stay with your leader and do not wander.

STOP 6b. Concrete dam across the Shawangunk Kill.
The first phase of the hike is about 1100 feet to a concrete dam across the Shawangunk Kill. On the far side of the stream and on the near side, when water is low, one can see an overturned section of east-dipping interlaminated siltstones and argillites which aggregate some 2000 to 2500 stratigraphic feet.
As far as we can tell, there is little faulting other than bedding plane dislocations and the sequence does not appear to belong in the complex domain. The differences between these strata and those at the next stop are noteworthy.
No samples in the dam area, please.

STOP 6c. The top of the argillite and silt sequence.
Proceed upstream from the dam along the berm of an abandoned canal. Watch out for woodchuck holes in the berm. They can be treacherous (the holes - not the woodchucks).
Proceed about 1,000 feet upstream from the dam to a point where a large hill on the north side of the stream closes to the stream. Here are numerous arenite layers in the shales, some up to a foot or so in thickness. These arenites are also overturned, dipping east as can be seen by flow structures on the basal bedding planes. This sequence seems to occur at the top of the argillite and silt sequence. The arenites can be traced southwestward into an ever-thickening arenite-shale sequence which seems to approximate the position of the Ramseyburg member in the Martinsburg Formation much further south. The argillite-silt sequence is most likely upper Bushkill if the foregoing is correct. This sequence in the Shawangunk Kill was first noted by Paul Kopsick (1977).

STOP 7. This extensive road cut is in the Bushkill shale
Walk uphill (west) along one side of highway and return, walking down other side. This extensive road cut is in the Bushkill shale and strata generally are right side up and dip east, but faulting and some drag folding suggest imbricate thrusting. This exposure is thought to represent a portion of the upper plate thrust over the lower plate exposed at STOP 6. A chance rockfall in this cut yielded an extensive fauna including bivalvia, articulate and inarticulate brachiopods, cryptolithid trilobites, graptolites, gastropods and burrows. Weathering rapidly reduces the shale to fine rubble.

STOP 8. Martinsburg strata may be Pen Argyl Equivalent
STOP 8. Here Martinsburg strata, which appear to be Bushkill, may actually be Pen Argyl Equivalent though they do not resemble the latter. Here and at STOP 9, a short distance away, the strata occur in the open fold domain and in the immediate vicinity the overlying Shawangunk conglomerate may reflect Acadian or later deformation which was superposed on a predominantly Taconian structure.

STOP 9. Scenic Overview and Field Trip Conclusions
Facing northwest we see the relative attitudes of the underlying Martinsburg (Pen Argyl Equivalent?) and the overlying Shawungunk conglomerate. Although the angular unconformity between the two can be projected, the actual contact can be seen just south of Rt. 44-55 at the base of the Shawungunk (Waines and Sanders, 1968). The study of the relative structure of the Shawangunk and Martinsburg in this immediate vicinity was conducted by Persico (1984). He concluded that same Taconic structures were further deformed at a later time.
Next, a view to the southeast and east stretches beyond the immediate Wallkill Valley to the Hudson Highlands and the Hudson River Gap (southeast) and the Housatonic Ridge along the Connecticut border to the east. Closer at hand, to the east, we can retrace our general progress of the day from the irregular ridge of the Marlboro Mountains (overturned east limb of the Marlboro Syncline). Slightly closer we drop in elevation across the east dipping monoclinal domain which cannot be recognized from this viewpoint. We know that the complex domain centers an the lower elevations of the Wallkill Valley, but again the domain cannot be recognized from here. Similarly, the open fold domain and its eastern boundary fault give no indication of their presence. It must be concluded that only extensive exposure data (borings, tunnels) are necessary to augment meager or fortuitous exposures as in Stops 6 and 7.

I: BLOCKSTREAMS AT MILLBROOK MOUNTAIN, TOWN OF GARDINER, ULSTER COUNTY, NEW YORK
ROBERT W. CUNNINGHAM
Department of Geological Sciences
State University of New York
College at New Paltz
New Paltz, New York, 12561
Peter A. Robson
MITRE Corporation
San Antonio, Texas, 78284
PURPOSE
To raise questions concerning the origin of the features found in the scree below Millbrook Mountain.
INTRODUCTION AND DESCRIPTION
Millbrook Mountain is a three quarter mile long anticlinal structure forming a topographic high (elevation 1620 feet, 495 m.). It is located about one mile south-southeast of Lake Minnewaska in the Shawangunk Mountains. This anticline is truncated on the east side by a 350 foot (107 m.) cliff and is composed entirely of Shawangunk conglomerate dipping up to 55 degrees to the northwest. While the vista from the top offers a commanding view of the Wallkill valley and Shawangunk Mountains, the most unusual and engrossing geomorphic features lie 500 feet below in the talus at the foot of the cliff forming Millbrook Mountains' south-east face. Instead of forming the 25 to 35 degree straight talus common to the Shawangunks, this scree displays a varied mixture of steep slopes, block streams, ramps sub-parallel to the cliff face, rampart-like ridges, valleys and closed depressions (figure 2).
These features are composed of blocks of Shawangunk conglomerate averaging five to ten feet cubed 1.5 to 3 m3, with some blocks forty feet (12m.) in length (Robson, 1972). These blocks are significantly larger than those in the scree presently being deposited at the base of Millbrook Mountain. Block streams are largely lacking vegetative cover, exposing the bright, white surfaces of conglomerate to view; this is what initially aroused the curiosity of Dr. Russell Waines who encouraged the initial studies of these talus features by Robson and Cunningham in 1972.
The block streams generally slope from one to ten degrees along their long axes, while the adjacent rampart-ridges slope at greater than thirty degrees. The steepest slopes are on the main rampart (figure 2) and attain a maximum angle of repose of 41 degrees (Cunningham and Robson,1973). Mature hemlocks up to three feet 1 m.) in diameter growing in several feet of humus cover the slopes and tops of the ramparts indicating a long period of stability. The block stream ramps, valleys, and depressions are barren rock with occasional small shrubs and sparse pines of small diameter. The newer talus forming at the foot of the cliff, and spreading onto the larger blocks supports mixed deciduous and coniferous trees of moderate size.
The steep, vegetated slopes, topped by the rampart-like ridges sit east of relatively unvegetated high valleys (figure 2). Block streams A and B descend up to 0.5 miles (0.8 km) north and south from valleys 2 and 3 respectively. Block stream C descends from valley 4 extending to the south then to the southeast. These contrasting surface features offer good evidence that this block scree has been redistributed about the base of Millbrook Mountain.
In the northern part of the area the heavily vegetated slopes have apparently remained stable, while the scree behind the main rampart has presumably migrated to the north and south leaving shallow valleys (2, 3) separated by a saddle.
Another feature occurs south of block stream C where a mass of scree, set out from the cliff face occurs as a domal structure (figure 2) with blocks dipping outward in all directions. A small vegetated area separates this structure from the unvegetated block stream to the north.
On the steep eastern face of block stream B, is an alignment of several thin, unvegetated crescents of scree trending horizontally and surrounded by vegetated slopes (figure 2).
When hiking on the talus below Millbrook Mountain good shoes are required! Good physical conditioning and agility are important. Permission of the owner is necessary! He lives just north of the target area up long driveway on the west side of the road.
Approach scree from below (east).

I: BLOCKSTREAMS AT MILLBROOK MOUNTAIN, TOWN OF GARDINER, ULSTER COUNTY, NEW YORK

STOP 1. Millbrook Mountain Scree Slope
Millbrook Mountain is a three quarter mile long anticlinal structure forming a topographic high (elevation 1620 feet, 495 m.). It is located about one mile south-southeast of Lake Minnewaska in the Shawangunk Mountains. This anticline is truncated on the east side by a 350 foot (107 m.) cliff and is composed entirely of Shawangunk conglomerate dipping up to 55 degrees to the northwest. While the vista from the top offers a commanding view of the Wallkill valley and Shawangunk Mountains, the most unusual and engrossing geomorphic features lie 500 feet below in the talus at the foot of the cliff forming Millbrook Mountains' south-east face. Instead of forming the 25 to 35 degree straight talus common to the Shawangunks, this scree displays a varied mixture of steep slopes, block streams, ramps sub-parallel to the cliff face, rampart-like ridges, valleys and closed depressions (figure 2).
These features are composed of blocks of Shawangunk conglomerate averaging five to ten feet cubed 1.5 to 3 m3, with some blocks forty feet (12m.) in length (Robson, 1972). These blocks are significantly larger than those in the scree presently being deposited at the base of Millbrook Mountain. Block streams are largely lacking vegetative cover, exposing the bright, white surfaces of conglomerate to view; this is what initially aroused the curiosity of Dr. Russell Waines who encouraged the initial studies of these talus features by Robson and Cunningham in 1972.
The block streams generally slope from one to ten degrees along their long axes, while the adjacent rampart-ridges slope at greater than thirty degrees. The steepest slopes are on the main rampart (figure 2) and attain a maximum angle of repose of 41 degrees (Cunningham and Robson,1973). Mature hemlocks up to three feet 1 m.) in diameter growing in several feet of humus cover the slopes and tops of the ramparts indicating a long period of stability. The block stream ramps, valleys, and depressions are barren rock with occasional small shrubs and sparse pines of small diameter. The newer talus forming at the foot of the cliff, and spreading onto the larger blocks supports mixed deciduous and coniferous trees of moderate size.
The steep, vegetated slopes, topped by the rampart-like ridges sit east of relatively unvegetated high valleys (figure 2). Block streams A and B descend up to 0.5 miles (0.8 km) north and south from valleys 2 and 3 respectively. Block stream C descends from valley 4 extending to the south then to the southeast. These contrasting surface features offer good evidence that this block scree has been redistributed about the base of Millbrook Mountain.

J: THE WHITEPORT DOLOSTONE OF THE LATE SILURIAN RONDOUT GROUP, VICINITY OF KINGSTON, ULSTER COUNTY, NEW YORK
Brian V. Fetterhoff
New Paltz, New York 12561
Introduction
The term Whiteport was proposed by Rickard (1962) for a dolostone referred to by Hartnagel (1903) as the 'Rondout' in a rather restricted sense. Rickard suggested "that the name Rondout be applied to the dolomite strata subjacent to the Manlius everywhere in New York" (p. 3O). Thus, according to Rickard, in the Rondout Formation the Whiteport is the uppermost of three members (Whiteport, Glasco, Rosendale), with a type section near Whiteport, New York.
Harper (1969) described the Whiteport as a "buff-weathering, light-gray to blue-gray on fresh, argillaceous silty dololutite. It is mudcracked, finely laminated, commonly burrowed, and very rarely fossiliferous" (p. 14). Harper's environmental interpretation is that of a mudflat facies. Harper acknowledged that lime interbeds do exist within the Whiteport in the vicinity of Kingston:
"One prominent interbed has been termed the "Twalfskill Bed" (Wanless, 1921; Van Ingen, local unpublished field term). Its thickness averages about one foot, and it is found to occur in the majority of sections in the Rosendale quadrangle... In this blue weathering, dolomitic limestone the fossils are commonly algal-coated, a fact which prompted Wanless to describe it as the "Algal Reef Limestone" (p. 14-15).
An additional limestone was recognized by Harper in the base of the Whiteport; a "two-foot interval of interbedded ostracod-rich calcarenites, calcilutites and calcareous silty dolomites" (p. 119).
Waines and Gomez (1977) divided the Whiteport (from Accord to Kingston) into five recognizable units (from top to bottom): Unit one, an argillaceous shaly dolostone (found south of Kingston), unit two, a massive weathering dolostone (unit one of this paper), unit three which can be subdivided into an upper, laminated portion and a lower, organic "reef" (unit two here), unit four, a massive dolostone (unit three here), and unit five, a somewhat fossiliferous lime unit (unit four here). This unit, which was often placed in the top of the Glasco, is actually a separate unit in the base of the Whiteport.
It is the presence of these limestone units which appear in the vicinity of Kingston that allows additional interpretations of environments and, due to their fossiliferous nature, a determination of age.

J: THE WHITEPORT DOLOSTONE OF THE LATE SILURIAN RONDOUT GROUP, VICINITY OF KINGSTON, ULSTER COUNTY, NEW YORK

Mt. Marion Formation (Middle Devonian)
For the next 2.1 miles are extensive roadcuts in gently dipping siltstones and shales of Mt. Marion Formation (Middle Devonian).

Roadcut shows Lower Devonian strata.

STOP 1A: Wygant North. Roadcut Exposing Thacher, Whiteport, Glasco, And Rosendale.
(PLEASE DO NOT CROSS HIGHWAY. BEWARE OF FALLING ROCK - WEAR HARD HATS.)
Whiteport
Thickness of Whiteport is five feet. Unit two is not present in this section, and unit one rests disconformably upon unit three.
Glasco
Note lower disconformable contact with massive dolomitic mudstones of the Rosendale. Coverstone lithology of unit A (subunit 2) characterized by laminar stromatoporoids; chiefly Stromatopora clarkei, intercalated with stick-like tabulates and/or bryozoa, and chert. Take note of the position of this unit in the stratigraphic sequence.
Distinct color change between unit B and C (dark blue vs. light grey). Bedding plane parting marks upper contact of unit C with overlying basal ostracod floatstones of the Whiteport. This unit in the lower Whiteport occurs in virtually all localities studied and serves as an excellent marker bed.

STOP 1B: Wygant South.
Please Do Not Cross Highway.
Whiteport
Unit four is well exposed at this stop. Note abundance of ostracods, and fragments of limestone (intraformational conglomerate) within this unit. Gradational contact with unit three. Unit one and two are not exposed at this stop.
Glasco
Hemispherical stromatoporoids and halysitids found in the basal hemstones are typical of the northern domain. Compare intact halysitid coralla with fragmented types in chainstone. Note laminar stromatoporoids in coverstone and chainstone lithologies of unit A. Pay particular attention to stromatoporoid/halysitid association in low matrix chainstone.
Dominant macro-invertebrates in unit B are solitary rugosa, cladoporid-like tabulates, and stick-like tabulates and/or bryozoa (especially in subunit 2). Unit C is characterized by fossil fragments. Note irregular disconformable upper contact and associated rip-up clasts.
Rosendale
At this location unit one is missing, probably due to erosion. Unit two is massive dolostone. Unit two subunit is a massive dolostone with discontinuous to continuous limestone stringers. Unit three, Wilbur is mottled and contains a fossil marker bed. The bottom portion of this unit is a sandy limestone which rests on Ordovician sediments with angular unconformity. Most likely, unit four was never deposited.

STOP 2: Vlightberg Hill. (Follow Fieldtrip Leaders Up Hill).
Please Follow Pink Ribbon Trail And Do Not Wander - Especially Dangerous Cliffs.
2A: Van Ingen's Wilbur
Rosendale
Unit three, Wilbur is massive but still has that mottled look. Here the limestone is in angular unconformity with underlying Middle Ordovician Normanskill (Austen Glen aspect) graywackes.
2B: South End Of The Vlightberg
Whiteport
Unit four is not present at this stop. Unit two is dolomitized, and the subunits are barely distinguishable.
Glasco
The Glasco is represented by unit C (subunit 2) which consists of dolomitic mudstones, indistinctly laminated dolomitic mudstone, end stringers of fossil hash with quartz grains. Similar horizons occur at stops 3, 5A and 5B.
A small mottled portion of unit one is present.

STOP 3: Sweeney's Stoneyard. (Follow Field Trip Leaders)
No Sampling At This Outcrop - When We Cross The Road Stay On Sidewalk. Do Not Walk On The Flower Garden.) Outcrop Descriptions Will Be Presented By Fieldtrip Leaders On Opposite Side Of Outcrop.
Best exposure for the Whiteport Dolostone in the Kingston area. Unit four is dolomitized at this stop. Unit two can be seen in its two subdivisions, the upper laminated subunit and lover 'reef* subunit. The three subzones within the lower subunit are best exposed here. Note disconformity at the base of units four, two, and at the top of unit two. At the top of of unit one, mudcracks mark the contact with the Thacher limestone.
Cherty boundstone is found near the base of unit A (very thin subunit 1). Unit B contains a lower dolomitic floatstone/lamstone (subunit 1). The upper dolomitic mudstone may be indicative of quiet water in the back reef environment. Note the highs and lows within the stromatoporoid knobs along with laminar and hemispherical stromatoporoids located at similar horizons. Take a close look at the overlying subunit 2.
Rosendale
At this stop all four units in the four-fold proposal are present. The upper limestone of unit one can be seen with its mottled look and a minor parting at the base. Unit two is massive dolostone which has several partings present. Unit three and unit four are present but are hidden behind the fence. Once again do not step on the garden and no samples please.

STOP 4: City Of Kingston Gravel Pit (Follow Fieldtrip Leaders).
The Cliff To The Northwest Is Formed Of An Extensive Sequence Of Upper Silurian And Lower Devonian Strata (Mostly Carbonates) Partly Repeated By Faulting.
Unit four is dolomitized at this outcrop. Fossiliferous horizons can be noted, with concave-down ostracod valves, brachiopods, and solitary rugose corals. Hemispherical stromatoporoids also present. Unit three is covered by talus; unit two can be seen in both subunits. Contact between unit one and overlying Thacher limestone is last mudcrack in unit one.
The cherty coverstone marker bed essentially sits at the base of unit A. The chainstone lithology has thinned relative to the north, contains more matrix and few, if any, laminar stromatoporoids. The cyclic nature of floatstone and lamstone within unit B is best demonstrated at this locality. The base of unit C shows an unusual stromatoporoid growth form. A vertical channel wall and subsequent infillings are encrusted by stromatoporoid coenostea (Parallelostroma constellatum). Once again take note of of the laminar and hemispherical stromatoporoids that seem to co-exist at similar horizons.
This stop represents the standard reference for the Rondout Formation and the type section of the Wilbur member. Here all four units of the Rosendale dolostone can be seen. The cliff to the northeast shows an extensive sequence of all four units. Unit one can clearly be identified below the base of the Glasco. The massive limestone is mottled and the upper portion is darker than the bottom. The Wilbur, unit three, is sandwiched between the dolostone of unit two and unit four. Unit four lies with disconformity on the underlying Binnewater Sandstone.

STOP 5: Callanan's Quarry.
Waiver forms must be signed releasing quarry and its employees of any liability, before entering premises. It is mandatory that hard hats and field boots be worn - no one admitted without such safety equipment. Follow fieldtrip leaders to designated localities. Do not wander - Extremely dangerous overhangs and cliffs.
5A: CALLANAN'S WEST: Field assistants will be on hand to assist (especially keeping fieldtrip participants aware of dangerous cliffs and overhangs). No climbing of any sort.
'Reef' subunit of unit two is present in this section. Undeformed halysitid coral found at this location. Unit four is almost completely dolomitized.
Cherty boundstone marker bed is once again located near the base of unit A. Take a close look at the burrowed horizon and high matrix chainstone (rare entire halysitid corals). Unit B is rather thick at this locality. Take some time to examine the stromatoporoid knobs and the overlying dolomitic mudstone and floatstone with occasional laminates, fissile debris and scattered hemispherical stromatoporoids. The latter was interpreted as a low subtidal to intertidal (?) flat environment.
At this outcrop all four units are present but due to faulting the beds are repeated several times. Unit one can be found sitting under the shale parting at the base of the Glasco. This mottled limestone has a parting at its base. Unit two massive dolostone has several partings. Unit three, Wilbur is mottled and also has several partings. The lower dolostone of unit four is massive with areas that are more calcareous. This dolostone lies disconformably on the underlying Binnewater Sandstone.
5B: CALLANAN'S EAST: Once again follow fieldtrip leaders. Stay away from edge of bench. Do not wander or climb!! Field assistants are instructed to keep field trip participants away from cliff. Stay away from roped off area.
Unit four is no longer present; unit three is over seven feet in thickness. Unit two is much thinner in than the western side of the quarry, and, due to the less abundant fossils within the lower subunit, is now 'off-reef'.
This locality has been the most problematic to decipher due to its seemingly "unusual" character. With the help of marker beds in the Whiteport and Rosendale the intricate nature of this exposure appears to have been clarified. Unit A as usual contains a lower coverstone/boundstone but only fragments of the chainstone remain. Unit B does not contain subunit 1 but is represented by a thick subunit 2 (5.4 feet) consisting chiefly of dolomitic mudstones with fewer floatstones (somewhat cyclic). Some beds are laminated and burrowed. The base of the unit contains wide, deep, vertical burrows that appear related to a horizon on the west side. Unit C is represented by subunit 2 and its associated mixture of dolomitic mudstones and floatstones, rudstones, and black shale at the top. These lithologies contain more fossil debris and quartz grains. Only unit C, at other localities demonstrates these associations.
Unit one, the mottled limestone, is represented in the the cliffs (very dangerous do not climb up talus). Unit two and its subunit along with the Wilbur can be seen on several boulders lying near by. Unit two is massive dolostone which is somewhat calcareous. Again unit two subunit is present, a dolostone with continuous to discontinuous limestone stringers. Unit three, the Wilbur, is mottled, and fossiliferous along with clasts of sandstone present near the base. The Wilbur sits on top of Ordovician sediments at an angular unconformity. Most likely unit four was never deposited here.

K: TIDAL CURRENTS, BIOGENIC ACTIVITY AND PYCNOCLINAL FLUCTUATION ON A LOWER DEVONIAN RAMP: BECRAFT, ALSEN, AND PORT EWEN FORMATIONS, CENTRAL HUDSON VALLEY
JAMES R. EBERT
Department of Earth Sciences
State University College
Oneonta, New York 13820-1380
The Helderberg Group (Lower Devonian) of New York State includes eight thin, but extensive formations that comprise two transgressive cycles separated by a minor regression (Rickard, 1962; Head, 1969; Laporte, 1969; Ebert, 1982, 1983). The lower cycle exhibits the classic deepening upward sequence of formations: Rondout, Manlius, Coeymans, Kalkberg, New Scotland (Table 1; Rickard, 1962; Laporte, 1967, 1969) that has been widely cited as an example of epeiric sea (ramp) sedimentation. The regression is recorded by an upper tongue of the Kalkberg Formation and the lower portion of the Becraft Formation (Head, 1969; Arif, 1973; Ebert, 1982, 1983). The upper transgressive cycle is comprised of the Becraft, Alsen and Port Ewen formations and has been assumed to represent a repetition of Coeymans, Kalkberg and New Scotland lithologies and environments (Rickard, 1962; Laporte, 1967). Gross similarity in outcrop appearance had been the only basis for this assumption. Recent descriptions of the upper cycle (Ebert, 1982, 1983, 1985, 1986; Mazzo, 1981, Mazzo and LaFleur, 1984) have indicated significant departures from the characteristics of the lower formations. Comparison of upper and lower cycles (Ebert, 1982, 1983, 1985) has resulted in improved understanding of the processes that operated on the Helderberg ramp.
Tidal sand waves are recognized in the Becraft Formation. This formation and other skeletal grainstone units have previously been interpreted as shoal deposits that accumulated above wave base. The predominance of wave action has always been assumed in these interpretations; however, analysis of sedimentary structures clearly indicates the dominance of tidal currents.
Tidal sand waves occur in a variety of modern environments, from estuarine channels to the open shelf. The simplistic, and possibly erroneous, interpretation of wave dominance in many coarse carbonates probably has led to inaccurate reconstructions of environments and paleogeography, especially when adjacent facies are poorly exposed.
The occurrence of tidal sand waves in a sequence that has been interpreted as representing sedimentation in an epeiric sea (Laporte, 1969) raises important questions about the processes that operate in such seas. Traditional epeiric sea models (Shaw, 1964; Irwin, 1965; Ahr, 1973) have treated these seas as being tideless (Hallam, 1981). These models regard the position of wave base as the primary factor governing the distribution of facies. Tides are considered to be absent or of negligible effect.
Significant tidal exchange in epeiric seas has been disregarded because of the supposed frictional difficulty of moving the tidal prism across such wide, shallow shelves (Shaw, 1964; Irwin, 1965; Mazzullo and Friedman, 1975; Hallam, 1981). Despite this bias, a tidal origin has been demonstrated for many quartz arenites from epeiric sea settings (e.g. Klein, 1970, 1971, 1975, 1977; Thompson, 1975; Johnson, 1975; Swett, Klein and Smit, 1971; Chafetz, 1977; Barwis and Makurath, 1978; Recently, Slingerland (1986) has developed a numerical model that supports the hypothesis (Klein, 1977; Klein and Ryer, 1978) that some epeiric seas could have been tide-dominated. This model for the Upper Devonian Catskill epeiric sea includes the geographic area of the present study. Tidal sand waves of the Becraft Formation and the model of Slingerland suggest that, at least, the shallow portions of the northern Appalachian Basin may have been tidally dominated throughout the Devonian. It should be pointed out, however, that deeper portions of the basin, especially during the Middle Devonian, were storm dominated (for examples, see Brett, 1986).
Biogenic processes played an important role in the Helderberg sea, as well. The Alsen Formation displays a predominance of biogenically-disrupted fabrics, although remnants of physical structures are also preserved. The overlying Port Ewen Formation also shows evidence of the importance of biogenic activity. A variety of ichnofossils are present in this unit. These traces provide a detailed record of subtle changes in water oxygenation on the deeper portions of the Helderberg ramp. Of particular interest are the cyclic variations in the distribution of Zoophycos, Chondrites and Helminthoida and associated lithologies. These cycles record fluctuations in the position of the pycnocline and its intersection with the sediment-water interface. These fluctuations occurred in response to regional transgression and record the shoreward shift in the location of the pycnoclinal intersection. Both symmetric and asymmetric cycles are recorded. Although PAC-like in scale, these cycles do not seem to fit the PAC motif of shallowing upward. Deepening upward and shallowing followed by deepening seem to be the more typical pattern for these cycles.

K: TIDAL CURRENTS, BIOGENIC ACTIVITY AND PYCNOCLINAL FLUCTUATION ON A LOWER DEVONIAN RAMP: BECRAFT, ALSEN, AND PORT EWEN FORMATIONS, CENTRAL HUDSON VALLEY

Outcrop on left displays Taconic unconformity

Rip Van Winkle Bridge toll plaza
Outcrops on both sides of road show chevron folds in the Austin Glen Formation, cross Hudson River $0.50 toll for passenger vehicles

Outcrop on corner is in Manlius Formation

Small outcrop of Normanskill Formation.
The hill to the right of the road is Becraft Mountain, an outlier of the Helderberg Group

STOP 1. Becraft Mountain
Inactive quarry of the Independent Cement Corporation on Becraft Mountain outlier ("Becraft Hills"), located in northeast quarter of the Hudson South, New York 7.5 minute quadrangle, just east of Rt. 9, approximately 1 mile south of Hudson.
References: Grabau, 1903; Rickard, 1962
Description: A small pit in the Manlius and Coeymans formations can be seen to the left of the access road to the main quarry. Before entering the main quarry, exposures in the New Scotland Formation are visible along the access road. The main quarry is quite extensive; however, we will concentrate on the northern end. The lower Helderberg formations are largely submerged, but excellent exposures of the upper formations may be studied throughout the quarry.
The upper contact of the New Scotland Formation is clearly exposed in the northern wall of the quarry. Above the New Scotland is a thin (1.8 m) unit that I interpret as the easternmost extension of Rickard's (1962) upper tongue of the Kalkberg Formation. Slightly less than four meters of Becraft subfacies 1 overlie this unit. Subfacies 2 (8.5 m) and subfacies 3 (1.8 m) occur above subfacies 1. The Alsen Formation (2.5 m) is the highest unit present in the quarry.
The eastern position of the Becraft Mountain outlier places this exposure in a more shoreward position relative to localities in the main outcrop belt of the Helderberg Group. This is clearly reflected in the character of the upper formations. Subfacies 1 for example, exhibits fewer and thinner silty interbeds and drapes than at other localities in the central Hudson Valley, an indication of stronger current action in shallower water. Holdfasts of Aspidocrinus scutelliformis are usually sparse in this unit. Elsewhere, this holdfast is abundant in subfacies 1. These two factors combine to give subfacies 1 an overall appearance that is similar to that of subfacies 2 at other locations west of the Hudson. Erosional surfaces and silt drapes within sets of cross stratification are the major features to be observed in subfacies 1 at this stop.
Subfacies 2 is clearly exposed in the quarry, but access for large groups is difficult and potentially dangerous. For this reason, this unit will not be observed here. The general character of subfacies 2 can be seen from a distance, however. Thicker bedding, coarser textures and an abundance of A. scutelliformis and Gypidula pseudogaleata differentiate this unit from subfacies 1. The relative freshness of the exposure and the coarseness of subfacies 2 make observation of sedimentary structures difficult. Interbedding of rudstone and grainstone is the dominant structure. This interbedding is interpreted as vertically accreted tidal bundles. Unimodal cross stratification is common in the center of the unit, but may also be present elsewhere.
Subfacies 3 occurs just below the Alsen Formation. This unit is superficially similar to subfacies 2, but may be differentiated by the presence of bioturbate fabrics and the rootlike holdfast Clonocrinus(?). This unit is readily observable in the quarry, but is better studied at STOP 2, owing to the weathered character of that exposure.
By virtue of its position near the pre-quarry ground surface, the Alsen Formation is better weathered than other units in the quarry. Sedimentary structures and textures are highlighted by this weathering. Nodular chert also helps to differentiate this formation. Herringbone cross stratification, argillaceous interbeds, vague grading and bioturbate fabrics are the important features to note. Faunal differences from the underlying Becraft are evident in the decrease in crinoidal debris and brachiopods and the obvious increase in abundance and diversity of bryozoans. The Alsen Formation at this stop displays significantly more physical sedimentary structures than at other exposures. This is further evidence of a shallower position on the ramp for this location.

View of Catskill Front across the Hudson

Excellent exposure of the Taconic unconformity on offramp.

Large outcrop in Helderberg Group
These exposures continue for next half mile, units show complex deformation (see Marshak, 1986).

STOP 2. Catskill Creek In Austin Glen.
CAUTION: TRAFFIC IS OFTEN HEAVY AND FAST-MOVING. CROSS TO SOUTH SIDE WITH EXTREME CARE.
Location: Waterfall and rapids on Catskill Creek, below and just south of the Rt. 23 bridge over the creek, approximately 0.35 miles northwest of the Rt. 23 bridge over I-87. The deep, narrow valley of Catskill Creek is known as Austin Glen or Leeds Gorge in this area.
References: Section 44 of Rickard (1962), Structural geology is described by Marshak (1986), STOP 2B, see also STOPS l and 2.
Description: The near vertical bedding at this location has created a natural dam across Catskill Creek. Resistant beds of the Glenerie Formation and the Upper Helderberg Becraft, Alsen and Port Ewen Formations form the dam and subsequent waterfall. Upstream from this dam, the creek has scoured out the less resistant Esopus Formation as it flows parallel to strike. In addition to these units, the top of the New Scotland Formation and the upper tongue of the Kalkberg Formation are also exposed just below the falls on the east bank of the creek.
The upper tongue of the Kalkberg Formation (4 m) and Becraft subfacies 1 (4.9 m) are strikingly similar at this location. The two are differentiated by the abundance of Aspidocrinus holdfasts in subfacies l. This designation follows Rickard (1962). Dune forms, silty and peloidal interbeds and drapes are the essential features to note in this part of the section. Herringbone and unidirectional cross stratification are common, with end-on views of troughs less common. Ripples and cross lamination occur in some of the finer interbeds. The increased abundance and thickness of finer lithologies, relative to STOP 1 suggest that this location occupied a slightly more offshore or down ramp position.
Becraft subfacies 2 (approx. 9.5 m) is exposed in the falls and on the west bank of the creek. Thick to massive-appearing bedding and a nearly white weathered color set this unit apart from underlying and overlying units. As at STOP 1 the coarse texture of this unit makes observation of sedimentary structures difficult. Crude bedding is apparent in some crinoidal, Gypidula - Concinnispirifer rudstones. Planar stratification, grainstone - rudstone interbedding, normal and inverse grading are present. These features are interpreted as upper stage plane bedding and vertically accreted tidal bundles. Cross stratification is present, but is difficult to observe.
Subfacies 3 (1.6 m) is only subtly different from subfacies 2 in overall appearance. This unit is recognized by the abundance of Gypidula and Concinnispirifer and by the pink, root-like holdfasts of Clonocrinus(?). Finer textures and in situ holdfasts indicate reduced turbulence and increased stability of substrate relative to the underlying subfacies.
The Alsen Formation (approx. 11 m) is noticeably darker, finer-grained and chertier than the underlying Becraft Formation. The fauna is enriched in bryozoans relative to subfacies of the Becraft Formation. Crinoidal constituents are less abundant and finer and brachiopods tend to be thinner shelled than in the Becraft.
Sedimentary structures have been largely destroyed by bioturbation. The increase in biogenically-disrupted fabrics and the paucity of physical structures, as compared to the Becraft Mountain exposure, also suggest a slightly more down ramp position for this exposure.
Approximately two meters of the Port Ewen Formation are exposed near the top of the section, just below the Glenerie Formation. The Port Ewen is a moderately fossiliferous, bioturbate wackestone to packstone at this section. Bryozoans dominate the fauna. Trilobites and ostracodes are also common. The Port Ewen is greatly thinned here by pre-Glenerie erosion. Large phosphatic and/or slightly pyritic cobbles in the base of the sandy Glenerie mark this disconformity. These features may be observed in the beds that make up the upstream portion of the "dam".

Note Helderberg outcrops on ramp.

Helderberg, Tristates, Onondaga Limestone and Hamilton Group
Outcrops of the Helderberg Group, Tristates Group, Onondaga Limestone and Hamilton Group may be seen along I-87 over the next 21.4 miles.

Bridge over Esopus Creek

Outcrop in Tristates Group and Onondaga Limestone.

Outcrops in lower Helderberg Group

Outcrops of Austin Glen Formation on ramp

STOP 3. Roadcut on Route 199.
Location: Roadcut through anticline in the upper Helderberg Group on Rt. 199, the approach to the Kingston-Rhinecliff Bridge over the Hudson River. Exposure is 0.7 miles east of the junction of 199 with Rt. 9W and 0.35 miles west of the Rt. 32 overpass.
References: STOP lb of Waines and Hoar (1967); STOP 3 of Heyl and Salkind (1967); STOP 3 of Toots (1976); STOP 9b of Pederson, Sichko and Wolff (1976); STOP 7 of Marshak (1986).
Description: This exposure has been visited on several previous NYSGA field trips for the purposes of illustrating structural features or stratigraphic succession. This trip will examine the sedimentology of the Upper Helderberg Formations exposed in this popular roadcut.
The Becraft Formation (9.5 m) occupies the core of this anticlinal exposure. Slightly less than two meters of subfacies 1 are exposed at the base of the section. Subfacies 2 comprises the remaining 7.6 meters of the formation. Subfacies 3 is absent, although the uppermost parts of subfacies 2 are somewhat similar to subfacies 3. Minor silty interbeds may be found in places in the lower parts of subfacies 2. These interbeds are commonly cross laminated and some show paleocurrent reversals relative to adjacent cross-bedded grainstones. Structures in the grainstones are difficult to observe on this relatively fresh face.
The Alsen Formation (6.3 m) sharply overlies subfacies 2 of the Becraft Formation, although several beds of Becraft-like grainstones are interbedded throughout the lower few meters of the Alsen. Bioturbate fabrics predominate in the grainstones and packstones of this unit. The contact with the overlying Port Ewen Formation is readily recognized, but appears to be gradational.
All five lithologies that make up the Port Ewen Formation (24 m) are present in this exposure. Cyclicity is most noticeable in the distribution of the nodules and beds of peloidal grainstone. Asymmetrical and symmetrical cycles are present.
Nodules are thoroughly burrow-mottled, except where recognizable ichnogenera are present, typically Chondrites and Zoophycos. Bioturbation is more intense within nodules than in the surrounding lithologies. Most nodules have sharp boundaries. However, some nodules exhibit a gradual decrease in the degree of bioturbation into the surrounding lithologies. Differential compaction between nodular and non-nodular lithologies is readily apparent. Note the absence of evidence for soft-sediment deformation which Mazzo (1981) and Mazzo and LaFleur (1984) suggest should be ubiquitous.
The distribution of ichnofauna within cycles is such that Zoophycos and Chondrites are most abundant in the centers of symmetrical cycles. Deeper water forms are present in the upper and lower portions of these cycles. Several nodular beds exhibit pyrite impregnation of the upper surfaces. Borings (?) are associated with these surfaces, as are pebbly, phosphatic and/or pyritic clasts that contain similar biogenic structures. Periodic exhumation of some nodular horizons and the development of patchy hardgrounds are suggested by these features. Additional evidence for early cementation is provided by synsedimentary fractures in some nodules that are partially cement-filled, with sediment overlying cement.
Chert is present as rinds that centripetally replace nodules of peloidal grainstone and as continuous beds that were originally peloidal. These features tend to be more common within five to eight meters of the contact with the Glenerie Formation.
Sandy, brachiopod-rich beds of the Glenerie Formation are present on the west limb of the fold. A covered interval of approximately 5 meters separates this formation from the Port Ewen below.

L: THE CATSKILLS REVISITED
Constantine Manos and Russell H. Waines
State University of New York, College at New Paltz
On this trip we hope to present an overview of sediments that accumulated to form the Catskill Clastic Wedge. Rather than develop a paper and field trip guide that deal entirely with new research, we plan to visit some outcrop locations that have already been reported in the literature, add one or two new locations, including a fossil collecting stop in the Mt. Marion formation, and travel to the Blenheim-Gilboa Hydroelectric Power Station north of Grand Gorge.
The study first begins in the post-Onondaga Bakoven shales at an outcrop in the Kingston area. These dark shales, deposited in a deep, euxinic marine environment, are successively overlain at other locations by mudstones, shales, and sandstones that comprise the first gray, and then red beds to be seen as we travel stratigraphically higher into the Catskill Front. The Stony Hollow formation, which we may see en route, was deposited on a distal prodelta slope. The first four stops are clustered a few miles within the trip's point of origin at locations where the Bakoven, then Mt. Marion mudstones, fossiliferous Mt. Marion iron-stained mudstones exposed in a somewhat remote quarry, and the Plattekill sandstones are exposed. The Ashokan formation, which underlies the Plattekill, was deposited on an intertidal shelf, while the Plattekill best represents a piedmont floodplain deposit.
From here, we will travel in a northwest direction through Shandaken, onto NY 23, then along NY 30 N past Grand Gorge to the Blenheim-Gilboa Power Station. On the trip towards Grand Gorge, we will be traveling on terrain mostly underlain by the Oneonta formation and have opportunities to view on our left, the valley of Schoharie Creek. The Schoharie is normally an underfit stream, although heavy rains during April, 1987 caused considerable flooding and erosion. The Blenheim-Gilboa Power Station, completed after World War II, employs waters of the Schoharie Creek, held in a main (channel-level) reservoir and an upper reservoir located on a plateau west of the Schoharie, to generate electricity for the Power Authority of the State of New York. A cluster of four stops in this area, which is essentially underlain by beds that are upper Hamilton and Tully equivalents, will include a visit to a sharply undercut slope in the Schoharie channel produced during the April floods, and a revisit to the Gilboa bridge, north of the Schoharie Reservoir. Near the bridge stand some of the stumps of the famous Gilboa Forest flora.
The return south through Grand Gorge and then eastward, will carry us to a unique exposure of the Oneonta formation, where we can be afforded the chance to examine a small, yet detail-packed outcrop, and discuss various ideas on the environment of deposition of these sediments. It is not a new outcrop, but apparently it is visited by geologists quite often, according to people living nearby, and this would seem to justify our return to it.
As we travel through Haines Falls to Tannersville, in a direction roughly perpendicular to the depositional strike (mean cross-bedding in this area near the Catskill Front has a vector of 297° according to Fletcher's 1967 paper), we will not be traveling "down-section" to any great degree. At Tannersville, we will turn towards North and South Lakes and stop at the edge of the Catskill Escarpment, nearly 2000 feet or about 700 meters above the Hudson Valley floor. Hopefully, we can reach this location before late afternoon. The view eastward, across the Hudson Valley to the Housatonic Mountains in the distance, is a grand vista. It should make any of us speculate on, and perhaps better understand the Acadian Mountains that were the high source terrain for the sediments that we revisited.
We hope that you will enjoy this trip, and rest secure in the comforting thought that there will be no examination at the end of the trip!

L: THE CATSKILLS REVISITED

STOP 1. Bakoven Shale.
The black shale and overlying siltstone section in the high road cut across the road area well described by Pedersen et al. (1976, Stop 7) and appear to represent the upper part of the Bakoven formation. This unit may represent initial deposition of a delta toe in a deep distal basin.

Mountain Marion escarpment and Esopus floodplain
Proceed along base of Mountain Marion escarpment (on right) with Esopus floodplain (bottom of glacial lake) on left.

STOP 2. Base of Mount Marion Escarpment.
Observe the variation in lithology, sedimentary structures, and fossils or lack of them. Can you find any reason for postulating the advance of a delta into the Bakoven basin such that these sediments represent deposition on a distal to proximal prodelta slope? Many blocks of Mount Marion, some quite large, have rotated with slow gravitational descent to give erroneous impressions of bedding plane attitudes along the escarpment.

Increasing sandstone bed frequency and thickness
We have been ascending up section and for the next 0.9 miles will note increasing sandstone bed frequency and thickness in the road cuts and nearby outcrops as we pass from Mount Marion to Ashokan beds.

'Slow Children' and Feral Dogs.
Close your windows and drive very slowly.

STOP 3. Quarry in Mt. Marion.
This quarry is probably in upper Mount Marion shales and siltstones. Fossils are exceedingly abundant in one horizon with articulate brachiopods and bivalves most abundant but many other types of fossils also occur. Some of these are very small and some are exceptionally large - especially two inarticulate brachiopods, Roemerella grandis and Lindstroemella aspidium.
Sheets of illustrated fossils will be passed out to help you identify your discoveries. A mug-shot of the fractal-like trace fossil Aristophycous will also be distributed. This specimen, obtained from this quarry, appears to be the only Devonian find recognized and is currently in private hands. Please help us find the other half of this specimen or another equally well-preserved. The specimen appears to have come from within six inches of the glaciated pavement at the north end of the quarry. Sandstones, possibly representative of the Ashoken formation, can be seen across the road to the west. The strata in the quarry may represent sediments deposited on the shallow, marine shelf of an advancing delta marine platform. The Ashoken sands may represent further shelf advance as intertidal shelf deposits.

At some point in the next 1.6 miles we will pull off highway and park on right.

STOP 4. Plattekill Formation.
In these 1.6 miles there are many good road cuts where the red and green sandstones and shales of the Plattekill formation can be seen. Look for lithologic changes and sedimentary structures which might indicate a piedmont floodplain environment.

STOP 5. Blenheim-Gilboa Power Station.
Hidden in the Schoharie Valley at this location, and designed to blend in with the natural landscape is one of six power stations operated by the New York Power Authority. The facility is located on the Lansing Manor Estate property, and the Lansing Manor Museum, housed in the 19th Century Manor House is nearby. A dam has been built to block the north flowing Schoharie Creek. Water is recycled between the lower reservoir and an upper one located on Brown Mountain to the east. The substation on the east side of the lower reservoir is not easily recognized from the visitors' center here, and the upper reservoir can not be seen at all. During times of high power demand, water is released from the upper reservoir to drive four turbine generators. Flow of Creek water northward beyond the dam is measured to match water intake into the lower reservoir whenever possible. The Creek here is underlain most likely by the Potter Hollow formation. The visitors' center contains a small museum that includes rock samples and one or two tree stumps.

STOP 6. Mine Kill Falls Overlook.
This is in part of a recreational site located just south of Lansing Manor. We will stop briefly here. At the north end of the parking lot we can view waterfalls of the Mine Kill as it flows eastward into the Schoharie Valley. The Manorkill formation overlies Potter Hollow gray and red beds, but the contact cannot bee seen from the observation platforms.

STOP 7. Erosion in Bend of Schoharie Creek.
This location is at a sharp bend in the Schoharie at the base of Bernt Hill, in marine facies of the Manorkill formation. Heavy rains during April, 1987 resulted in severe flooding of the Schoharie that caused much erosion in several places, sometimes undercutting nearby roads. This is what we see here on the west side (undercut slope) of the bend. Moderate gullying also developed on the opposite (far) side of the road in this area, but road crews have repaired most of the damage. Please watch your step, and do not walk too close to the edge of the rock ledges.

STOP 8. Tree Fern Trunk Display.
A well known display, about a half dozen stumps that are identified by Banks et al. (1985) as progymnosperms which represent typical remains of the Gilboa Forest, uncovered during quarrying operations near here. The trees probably grew to a height of about 60 feet (18 meters), and the specimens we see are mostly Eospermatopteris. The stumps were found in the lower Manorkill beds (and upper Potter Hollow?), which are assigned to the upper Hamilton Group. Although we will not make the attempt, a trek across the bridge and then southward along the Schoharie Channel leads to the east side of the Schoharie Reservoir (see Figure 3), where, during times of lower water levels, cross-bedding and occasional molds of small stumps may be seen in the light gray sandstone near the water's edge.

STOP 9. Fluvial Facies (?) Red Beds.
NO ROCK HAMMERS, PLEASE! This small outcrop is unique in terms of what it has to offer in one package. It consists primarily of three lithologic divisions in a coarsening-upwards sequence with distinct cross-bedding in the uppermost unit, and a small channel cutout on the left (west) side of the outcrop. The top surface of this rock exposure shows a top view of the cross-bedding structures, and a glacially smoothed and striated surface. Buttner (1977) referred to this outcrop as possibly representing a transitional facies (we assume transitional between meandering and braided fluvial systems). What interpretation can you obtain from this outcrop? (Oneonta formation here.)

STOP 10. Catskill Escarpment.
NO ROCK HAMMERS, PLEASE! Site of Catskill Mountain House. Although Figures 4 and 5 show details of topography and stratigraphy of the Catskill Clastic Wedge and the Catskill Front respectively, we feel that Figure 71B on page 139 of Dunbar and Rodgers (1957) is unexcelled in depicting lithologic boundaries, and the Catskill facies crossing time lines, in a simple yet effective way. We are on the very edge of the escarpment, and Palenville is about 1700 feet (520 meters) below us, while the Hudson River farther to the east is at a level that is about another 165 meters lower. We can easily see (hope for a clear day) the Rowena Memorial School Building, built in 1899 in Palenville, and made of Becraft limestone (Helderberg Group). The Catskill Mountain House was a resort hotel first built here in the early 1800's, and enlarged over the decades to become one of the most notable vacation sites in the East. After the turn of the century, its popularity began to decline somewhat, and reportedly, the steel rails used for conveying passengers by a train system up to the level of the escarpment were torn up and scrapped for the war effort in World War I. Although there were changes of ownership, the hotel continued to serve tourists until the late 1940's. By the late 1950's the building was judged to be beyond repair, and on a pre-dawn winter morning in the early 1960's, it was set afire by State authorities. Whatever part of the wreckage that could not be removed was pushed over the escarpment to the slopes below. Today, the view to the east is as spectacular as it was for hotel guests who sat on the front porch which was located very near the edge of the escarpment. At this location during late Devonian time, there was perhaps another mile of sediments above us. Projecting, in our minds, the trend of these sediments upward to the east as we view the present Housatonic Mountains beyond the Hudson River, we can begin to comprehend the elevation of the Acadian Mountains source terrain. Red bed sandstones and conglomerates with much cross-bedding evident, can be seen along the escarpment here.