NYSGA 1985
NEW YORK STATE GEOLOGICAL ASSOCIATION
57th Annual Meeting
FIELD TRIP GUIDEBOOK
Richard H. Lindemann, Editor
Department of Geology Skidmore College
Saratoga Springs, N.Y.
12866

A1: A TRIP TO THE TACONIC PROBLEM AND BACK
PHILIP C. HEWITT
Department of the Earth Sciences
SUNY College at Brockport
Brockport, NY 14420
INTRODUCTION
The purpose of this paper is to provide background information needed for both the full-day trip (A1) and the half-day trip (B1). The full day trip involves data from the entire paper while the half-day trip concentrates on the Taconic Problem primarily. However, to understand either day fully, the entire paper must be read. A separate Road Log for each trip is provided at the end of the paper.
The paper describes geologic features to be examined in area from Saratoga Springs, N.Y. to Manchester, Vt. A discussion and overview of the Taconic region and the "Taconic Problem" will be presented. Consideration will be given to both the sequential and fault hypotheses proposed for the High Taconic region.
The Taconic region is subdivided into the High Taconics and the Low Taconics based on the extreme difference in relief. The High Taconics are the mountains of Vermont, west of the Vermont Valley, with elevations of approximately 3000-4000 ft. The Low Taconics are the hills primarily in New York, west of the High Taconics, with elevations up to approximately 1500 ft. (Hewitt, 1961a). Lithologic and other distinctions will become apparent in the later discussion.

A1: A TRIP TO THE TACONIC PROBLEM AND BACK

STOP 1. The Springs, Tufa Terrace, And Flat-Lying Snake Hill Shale
The Spring along the pathway is typical of the mineralized and carbonated springs in the region. Do taste the water but with caution. Firstly, the water at this Spring passes through the dark shale and therefore, contains iron and sulfur. The amount of sufur is sufficient to "surprise" the unwary. Secondly, the water contains the radioactive gas radon. Thirdly, the bedrock from which the water rises is a dolostone and in addition to the calcium it contains magnesium. Therefore, this water is an excellent laxative. "A word to the wise is sufficient."
All of the springs are the result of the expansion, along the faults, of carbon dioxide gas released by the weathering of dolomite at depth. Acid water percolates downward to the dolostone, weathers the rock and forms mineralized water plus gas. As the water reaches the faults the carbon dioxide gas expands with the reduction of pressure and the gas carries the water to the surface.
The "Island Spouter" is, of course, not truly a geyser. In this case it is gas within a constricting pipe which allows the water to spurt into the air.
Walk north approximately 500 ft. along the path. Note dark gray to black flat-lying shale. Approximate equivalents to these shales (Snake Hill, Canajoharie?) will be seen later as metamorphic rock. These shales are medial Ordovician in age.
Note the Tufa Terrace. Formed of colloidal and precipitated calcium carbonate from the Spring on the hill above (west) the terrace. Here leaves and insect fossils are formed each year as the organic material is trapped, coated and then permineralized with the calcium carbonate.

Sand dunes.
Some totally and partially exhumed. Probably from Lake Albany equivalent. Note long axes to west. Possible 5 minute "extra" stop here if time permits.

View of Taconics ahead (east).

Saratoga National Monument on right.
Battle of Saratoga took place here during Revolutionary War.

STOP 2. Stark's Knob Area. Folded, Distorted Shale
Note badly distorted black shale on right side of road. These are equivalent of those at Stop 1 (Snake Hill). This is part of Logan's Zone and the rocks are faulted, badly fractured and somewhat metamorphosed. Note limestone and dolostone pebbles (gray to blue-gray) in shale and oxidation of parts of shale surfaces. Limestone and dolostones are not indigenous to this locality. They are from the area far to the east. We will see these later in the day in situ. The red oxidized zone probably represents a "baked" zone as the area moved westward during faulting. The "baking" might also have resulted from the emplacement of the basaltic pillow lavas of which Stark's Knob is composed.
Walk uphill and to the right for a quick examination of Stark's Knob.
This is a flow of basalt (now pillow basalt) which apparently formed when lava flowed into the sea and across a shaly (or muddy) shoreline with fragments of limestone and dolostone present. The lava and the shale which enclosed it were later thrust westward during the faulting which produced Logan's Zone. We will see basic material similar to this lava but as dikes on Rt. 7 in Vermont. Stark's Knob was formerly used as road metal.
The basalt and the shale are both of medial Ordovician age. Return to cars.

Note folded black shales on right side of road along route.

STOP 3. Folded Wallomsac Formation
This outcrop exposes typical black slate and metamorphosed sandstone (now quartzite) of the Walloomsac formation. Strata here are strongly folded and thrust faulted. Cleavage is readily visible. There is some mineralization along the faults. Folds of various magnitudes may be observed here. This outcrop expresses well the folding in the Low Taconics. Virtually every bed is slickensided. Some folds show evidence of refolding.
No fossils have been found to verify the age of this outcrop. However, it maps well into the Walloomsac which is generally considered to be medial Ordovician (Trentonian) in age. It is probably correlative with the Snake Hill. However, lithologically it resembles the Austin Glen member of the Normanskill formation more closely. This unit is believed to be older than the Snake Hill but still medial Ordovician.

Black slates and phyllites on both sides of roads.
Black slates and phyllites on both sides of roads. These are visible in many locations along the road.

STOP 4. Green Slate And Black Slate Outcrop
Green slate (or phyllite) is exposed on the left (northwest) side of the road. Black slate (or phyllite) lies across the road on the southeast side. The decision as to whether these are slates or phyllites is rather subjective since they appear to border both lithologies. Beds appear to dip to the southeast which is common in the area. The green slates appear to lie under the black beds. The age of the black phyllites is probably medial Ordovician since they are on strike with the Walloomsac beds. If so, they lie above green beds which, in many ways, resemble those of the beds further east in the High Taconics. The green slates are also on strike with known Cambrian beds of the Mettawee slates (the famous purple and green slates) in the Taconic sequence. Some few purple beds are seen at this locality also but they are better exposed 1.6 miles northeast along Rt. 313. Purple and green Mettawee slates are well known in the northwest part of the Equinox quadrangle. The author considers the green slates to be Cambrian Mettawee formation and the black slates to be Walloomsac. In this case a major unconformity is present. This is probably the unconformity recognized by MacFadyen (1956), Thompson (1959) and others. Return to cars. Continue on Rt. 313 to northeast.

Interfolded black and green slates.

Purple and green slates.

Tight folding, chevron folds in green phyllite
Tight folding, chevron folds in green phyllite (Mt. Anthony fm.) in Vermont. On left (north). These are the same phyllites which lie over the carbonate in the High Taconics. Since crossing the State Line into Vermont, we have been in the High Taconics.

STOP 5. Ordovician Carbonate Outcrop
Covered Bridge on right (south) and dolomitic marble outcrop on left (north) Pull to right past Covered Bridge and park.
This outcrop of medial Ordovician gray to blue-gray dolomitic marble contains many fossil fragments (crinoid, cystoid and related groups) and a few remains of a Trentonian cephalopod (probably Endoceras proteiforme). This establishes these strata as medial Ordovician in age. Although these beds resemble closely the Bascom-Beldens (undifferentiated), the age is too young. The Bascom-Beldens is generally considered to be of early Ordovician age. Therefore, these fossiliferous middle Ordovician rocks were mapped separately and with the associated black phyllite as the lower Mt. Anthony formation (Hewitt, 1961a). If the upper part of the Beldens could be demonstrated to be Trentonian (medial Ordovician) these beds could easily be placed, on purely lithologic grounds in that formation.
The strata at this outcrop directly underlie the green phyllites of the High Taconics assigned to the Mt. Anthony formation (MacFadyen, 1956). It is the nature of the contact between these units that is the crux of the present Taconic problem (see paper preceeding this Road Log for details). Some evidence of that contact will be seen at a later stop and more definitive evidence is presented at Stop 2 of the Road Log for the trip entitled "The Nature of the eastern Taconic Contact."
Although some observers may conclude that the folding at this locality is not extreme, it should be noted that green phyllite probably lies below the surface as well as above the carbonate. Many of the beds are up-sidedown and generally the outcrop is an inverted section at road level. Further up the hill above (north) the road the strata are right-side-up.
Some sandy beds show cross-bedding that helps to establish this but the extreme overturning of these folds will be very apparent as the field trip progresses. The nature of the synclinorium actually requires this as our eastward travel will demonstrate. Please return to the cars and drive east, staying on Rt. 313. Note carbonate on drive eastward. We will examine these later.

This is the west side of the Vermont Valley.
Outcrops within the Valley are Cambro-Ordovician Valley sequence strata. On right (east) are the Green Mtns. of Precambrian to earliest Cambrian age.

View of Mt. Equinox ahead.

Delta deposit on left (west) from post-glacial lake (Lake Bennington?).

STOP 6. Mt. Equinox
No mileages will be provided for the drive up Mt. Equinox since easily recognizeable stopping places have been provided. Drive carefully both up and down the mountain! If you do not have faith in your car's brakes and transmission do not attempt the drive. The drive will test your car.
The road up starts gently in the Shelburn formation with a lower member (Sutherland Falls) of creamy to white calcitic marble, a middle (Intermediate dolomite) member and an upper Columbian marble, the commercial marble of the Vermont Marble Belt. None of this formation is exposed until the first bench or terrace is reached. Elsewhere on the mountain, excellent exposures of all three members are easily observed.
Park at the Parking Lot at the first terrace. This is our lunch stop. Rest rooms are opposite the Parking Lot about 300 ft. to the south. Enjoy the view but please keep the area clean.
Before returning to the cars, gather at the picnic tables for a discussion of the geology, history and culture of the mountain. If time permits we will visit a small marble quarry about 900 ft. north of the Parking Lot at an elevation 100 ft. lower than the Parking Lot. You may collect at this quarry. Return to cars and continue drive up the mountain. Do not stop on the road but note when green phyllite first appears. This occurs after first private road on your right (northeast). Continue climb.
Park at Parking Lot on second terrace. This locality is in the green phyllite. It provides excellent samples of the phyllite, pyrite cubes, and pseudomorphs of limonite (goethite) after pyrite, particularly in the northwest part of the exposure. Collect all you want. Return to cars and continue climb.
At first flat area, note Little Equinox Mtn. on right (southeast) and Lake Madelaine on left (west). Note also areas of landslides on right (east) side of sharp turns near top of Mt. Equinox. One of these will be climbed on foot on the trip discussing "The Nature of the eastern Taconic Contact".
At the summit, park but leave car engine running at fast idle for a few minutes before shutting down. This will help cool the engine. Gather in Parking Lot for orientation, geomorphology and overview of Taconic area.
Descend mountain. Keep car in LOW GEAR while descending. Brakes have been known to fade and even burn on descent. Stop at first flat area below summit for view of Lake Madelaine and monastery. Lake Madelaine is totally artificial. That area was formerly Big Spruce Swamp. Continue to base of mountain. Stay in LOW GEAR.

Note Cook Hollow on left (west).
White flat outcrop is Table Rock composed of white marble (Columbian?), Landslide Scar visible above Table Rock. This is carbonate-green phyllite eastern Taconic contact. Hewitt (1961a) concludes that this is a gradational contact.

STOP 7. Dolomite Outcrop. Basic Dikes
This is the Winooski dolostone of medial Cambrian age. Bedding and jointing permit blocks to fall easily so caution is important here. Note basic dikes in wall of exposure near north end.

STOP 8. Overturned Fold
This structure is a classic fold in the Bascom-Beldens formation. The lithology is dolomitic marble and the folding is typical Taconic folding. BE CAUTIOUS AT THIS OUTCROP. FOLLOW DIRECTIONS OF THOSE DIRECTING TRAFFIC. THEY ARE THERE FOR YOUR PROTECTION.

STOP 9. Carbonate-Green Phyllite Contact
Turn left (northwest) over one lane bridge. Corkscrew turn in folded Mt. Anthony formation. Drive through turn and turn at next intersection and reverse direction. Park at end (southeast) of large outcrop.
The green phyllite (Mt. Anthony formation of MacFadyen (1956)) is well exposed here. Intense folding is obvious. These are small folds on successively larger folds in this area. With care, small folds may be collected here. All of this section appears on first glance to be green phyllite. However, at the southeast corner of the last outcrop on this road the application of cold, dilute hydrochloric acid results in effervescence at the base. It is impossible visually to locate the horizon at which calcium carbonate ends and the phyllite begins. Only an acid reaction or lack of it can determine the difference. Is there a fault here or not? It is up to you to decide. Note the valley to the south. Is this a depression within the phyllite or the result of solution of a carbonate? No outcrops have been located within that depression but plentiful float is found there.

A2: THRUSTS, MELANGES, FOLDED THRUSTS AND DUPLEXES IN THE TACONIC FORELAND
WILLIAM BOSWORTH
Marathon International Oil Company P.O. Box 3128
Houston, Texas 77253
WILLIAM S. F. KIDD
Department of Geological Sciences
S.U.N.Y of Albany
Albany, New York 12222

A2: THRUSTS, MELANGES, FOLDED THRUSTS AND DUPLEXES IN THE TACONIC FORELAND

STOP 1A. Potsdam Formation
Quartzites, arenites and dolomitic micrites of the Potsdam Formation (medial Cambrian). Williams Street in Whitehall.
Grenville gneisses are exposed in the riverbed directly below this outcrop; although the unconformity is not exposed here, it is elsewhere along strike north and south. The main purpose of this stop is to see that the strata in this outcrop show no prominent signs of deformation, being part of a gently east-dipping regional homocline. Although not a main focus of this field trip, the evidence for both shallow marine to beach facies (prominently cross-bedded and rippled clean arenites and quartzites) and lagoonal supratidalflat facies (dolomitized micrites and thin shales, laminated in places with small stromatolites and locally with sand-filled vertical burrows) are well displayed here. Some layers, with pebbles of dolomitized micrite, may well be storm deposits.

STOP 1B. Limestones of the Whitehall Formation (late Cambrian).
Sciota Road 1.6 miles from Whitehall. These strata also are part of the regional gently east-dipping homocline of autochthonous shelf strata (typically 5-10 degrees east dip). No folds or cleavage are visible in these strata, and oolites which are locally abundant in some beds do not appear strained to any significant extent. Stylolites do occur in some beds but they are bedding-parallel, presumably compactional in origin. Laminated algal micrites, locally stromatolitic, can be seen, along with micrite edgewise breccias with oolites, all evidence of shallow marine to intertidal/supratidal facies. Nodular chert layers occur locally in this outcrop. It should be emphasized that most of the volume of the pre-medial Ordovician autochthonous shelf sequence is dolostone. Limestones form an overall small proportion and this unit (part of the Whitehall Formation) is, after the medial Ordovician limestones, the most prominent limestone in the early Paleozoic shelf sequence. Dolostones occur at the east end of the quarry where the outcrop nears the road - we will not examine these.

STOP 2. Thrust of limestones over shaley melange.
Thrust of medial Ordovician Isle la Motte (or Middlebury) limestones over medial Ordovician shaly melange. Locality indicated with an "X" on Fig. 2.
Carbonate exposures such as this one form lenticular belts bounded by medial Ordovician shales and finegrained wackes (flysch) in a zone near this vicinity a few kilometers wide between the western edge of the Taconic Allochthon and the eastern edge of gently east-dipping, unfolded strata that rest with intact unconformable relationship on crystalline Grenville basement (such as those exposed at Stops la and b).
Where contacts are exposed, such as here, and Stops 6 and 9, evidence for faulted lower contacts of limestone over shale are seen. In particular, the underside of the limestone is coated with fibrous vein-type slickensides, the lineation plunging close to down-dip. Truncation of stratification in the limestone is seen locally. An abundance of veins in the limestone within about 50cm of the thrust surface suggests hydrofracturing and high fluid pressures during thrusting. A crude, lenticular cleavage in the underlying shales is deflected adjacent to the fault surface. A small horse of shale, isolated above the main thrust surface by a duplex mechanism , can be seen approximately half way along the exposure of the. thrust (Fig. 3). Towards the western limit of the overlying carbonate sheet a detached sliver of carbonate about a meter long lies in the cleaved shale just below the prominent fault surface. This may be a structurally detached piece or (less likely because of its shape) an olistolith. Similar lozenge-shaped pieces of medium-grained graywacke up to about 1/2 m long occur sparingly in the phacoidally-cleaved shale in the western part of the cut. Slickensided surfaces suggest that they too are products of structural disruption ("structural slicing"), although an olistolithic origin cannot be discounted. The shale and siltstone is locally bedded, with minor folds in part of the outcrop. Most is pervasively disrupted by the phacoidal cleavage whose microstructural character, with abundant evidence for shear offsets, is clearly related to faulting (Bosworth and Vollmer, 1981; Bosworth, 1982, 1984). This carbonate and other exposures like it are shown on the New York State geological map and by Fisher (1985) as giant olistolithic blocks. We find this interpretation of the outcrops to be unconvincing and prefer an interpretation, as shown on Fig. 2, where the carbonates and stratigraphically overlying shales form thin thrust sheets accreted beneath the Taconic Allochthon. Demonstrable tight folds and internal duplex faults within these carbonate sheets account for the many places where stratigraphic continuity is disrupted within them.

STOP 3. Pre- to syn-cleavage thrust
Pre- to syn-cleavage thrust of Poultney Formation over gray slates, above Taconic Frontal Thrust. Locality marked "P" on Fig. 2.
Plude's Quarry (Fig. 4) provides one of the few known exposures of Taconic continental rise rocks lying directly upon the underlying melange/flysch sequence. Several complexities of Taconic thrusting are evident at this stop. Along Carleton Road the shales and graywackes of the Taconic flysch are broken into a melange fabric, that grades up into the quarry with progressively less disruption, until a planar slaty cleavage is found. This is the Taconic Frontal Thrust, and can be mapped as in Fig. 2. Within the quarry a second, earlier fault is present, separating easily identified Lower Poultney slates and thin arenites from an underlying gray slate. The regional slaty cleavage cuts the fault, suggesting that this structure may be of the same generation as Rowley and Kidd's (1982) "Taconic Basal Thrust". 'The gray slates are interpreted to be a unit within the Middle Ordovician Taconic Flysch (allochthonous? parautocththonous?), and hence the fault is inferred to be a thrust. Fig. 4. Exposed pre-slaty cleavage thrust in quarry face (Plude's Quarry, Stop 3; location marked "P" on Fig. 2). Allochthonous Poultney Formation rocks were thrust over gray shales and then folded and cleaved. Thrusting and folding were apparently in part synchronous, as the amplitude of the fold in the thrust surface in the easternmost anticline is less than the amplitude in the folded Poultney. The gray slates most closely resemble a flysch lithology, although whether it is allochthonous or parautochthonous flysch cannot be demonstrated without biostratigraphic control.

STOP 4. Delaware and Hudson Railroad cut
Delaware and Hudson Railroad cut 300m NE of crossing Whitehall-Fairhaven Turnpike. Locality shown with "R" on Fig. 2.
At the east end of the cut (Fig. 5), both sides expose thinly laminated, brown fine-grained arenites in dark slate belonging to the upper Hatch Hill or lowermost Poultney Formations (Cambrian - earliest Ordovician) of the Taconic Allochthon. These are in contact across a steep fault with thicker bedded coarse dolomitic (locally calcareous) quartz arenites and quartzites in black slate of the middle to lower Hatch Hill Formation *(mid-late Cambrian). In the western portion of the exposures, best seen on the northern side, these dark slates, with variable quantities of arenite beds, are in repetitive thrust fault contact with massive greenish micaceous wackes of the (Taconic) Bomoseen Formation (early Cambrian or older). At the western end of the cut, the last exposure contains a fold in Hatch Hill slate and arenites such that bedding surfaces in the slate form the face of the exposure on one limb of the synformal fold. This western end is close to but not quite at the Frontal Thrust seen at Stop 3. On the hill to the north a southward-thinning thrust sheet of shelf limestones occurs between shaly melange below and Taconic rocks above, such as are seen in this cut and at Stop 3. A unit of shaly melange up to a few meters thick occurs between the limestone and the Taconic rocks, and was seen at Stop 3. The western part of this exposure, with the complex slicing and phacoidal cleavage in the black argillite, can be regarded as transitional, in a structural sense, to the melange. The disposition of the Hatch Hill and Bomoseen can be interpreted as an earlier thrust that has been folded and cut by younger, more steeply inclined thrust faults. Fig. 2 shows that the occurrence of a Bomoseen-derived slice immediately above the Taconic Frontal Thrust, followed by a Hatch Hill/Poultney-derived slice, is characteristic of much of the Taconic area bounded by the folded thrust that occurs near the Allochthon boundary in this region. Structures in the railroad cut that we connect with the emplacement of the thrust sheet are fault-related features, particularly slickensides, summarized in Fig. 6. A Riedel and anti-Riedel fault set are interpreted to be present and are consistent with thrust movement towards the west-northwest. We emphasize the brittle nature of this deformation.
* bolded material was inadvertently omitted from the printed copy in the published field guide

STOP 5. Mettawee River Section
Parautochthonous flysch in contact with autochthonous(?) shelf carbonates. Lunch stop; location given in Fig. 7.
The Mettawee River here provides a superb series of exposures that cross from autochthonous(?) shelf carbonates (where we will stop for lunch), through alternating zones of flysch and melange, to a large sliver of Chazyan carbonate, and on into allochthonous Taconic lithologies (Fig. 7). The only area that is poorly exposed in the river is the eastern edge of the carbonate sliver, but mapping demonstrates that this fault contact (the Taconic Frontal Thrust) cuts obliquely across Taconic stratigraphy and large-scale fold axes, and is therefore a post-slaty cleavage generation structure (Figs. 7, 8).
As at Stop 2, some workers are of the opinion that the allochthonous carbonate at this locality (D.W.Fisher, pers. comm.,1983) and along the western edge of the Allochthon in general (J.Rodgers, pers. comm., 1983; Rodgers and Fisher, 1969) is better interpreted as blocks-in-shale (i.e., olistoliths) than as coherent fault slivers. This locality provides an excellent means to test these two hypotheses. The carbonate/melange contact can be walked from point "X" to point "Y" (Fig. 7) with little difficulty (after wading across the Mettawee.... access at "Y" is limited by buckshot). The carbonate is seen to be continuous, essentially unbroken along strike, with internal fold axes approximately parallel to the general contact trend (see Selleck and Bosworth, 1985, Plate 1A). The carbonate must be in the form of a large sheet, or composite sheet, which could be called a single "block". Minor disruption near its margins is undoubtedly present, but the structural style is dominantly detachment of underlying autochthonous shelf rocks and their imbrication at the base of the advancing allochthonous thrust pile. It is misleading to describe the geometry of the large carbonate bodies along the western edge of the Allochthon as "blocks-in-shale", and it is very unlikely that they arose as sedimentary slump features (further discussed in Rowley and Kidd, 1982).

STOP 6. Imbricated carbonates, shales and melange
Imbricated medial Ordovician carbonates, shales and melange just below the Taconic Frontal Thrust. Vermont Route 22A 6.5 km north of Fair Haven. Location shown with arrowhead on Fig. 9. The part of this roadcut to be examined is illustrated in Fig. 9, and consists of the outcrop opposite the parking area and its continuation to the north. A thrust-repeated section of medial Ordovician strata is discernable from medium-bedded limestone (fossiliferous calcarenites to calcisiltites) without shale - Orwell Limestone, passing up abruptly into thin-bedded limestones (micrites) interbedded with dark shale - Glens Falls Limestone, overlain by dark shale, in part melange - here referred to as Hortonville shale (and the melange perhaps as Forbes Hill "conglomerate"). It is important to recognize that the dark shale, in the first instance, is a stratigraphic member of this succession, just as it is in the autochthon to the west (e.g., in the Mohawk Valley). That some of it has been structurally damaged by the imbrication and duplication of the sequence is a secondary effect, reflected in the lenticular (phacoidal) cleavage visible especially in the shale closest to the base of the succeeding limestone. Two of the eight sections lack the basal Orwell Limestone, probably because of local ramping of the active thrust, or original irregularities in the depositional arrangement. It is not valid, in our view, to regard this exposure as "all melange" with blocks of limestone floating in shale. Rather, it is a thrust-imbricated repeated lithic sequence, probably forming a thrust "duplex" above more extensive shaly melange, not containing limestone clasts, that is exposed on the slope to the west of the parking lot and in the separate road cut on 22A about 100 m north of this outcrop. The duplex is below the Frontal Thrust of the Taconic Allochthon which comes to the surface about 50 m east of this road cut; wackes of the Bomoseen Formation of the Allochthon form the prominent topographic feature of "the Great Ledge" visible to the east from the parking lot. More extensive massive limestones (Orwell, and perhaps Middlebury Limestone as well) that form road cuts along 22A just to the south are thought to be larger slices in the duplex zone. Noteworthy in the narrow (less than 1m) zones of shaly melange beneath each slice of limestone in the cut are a few blocks and cobbles of green micaceous arenite identical to the Bomoseen Formation of the Allochthon. The largest of these (approx. 1 m across) occurs at the very northern end of the outcrop, but other smaller ones occur within the outcrop near 30-40 m on the diagram. These we do interpret as olistolithic clasts shed from the front of the Taconic thrust sheet during its motion, and they require that the active thrust outcropped on the sea-floor, at a deep-sea trench-type feature. A similar, but larger (several m across) olistolith of Bomoseen wacke occurs in the outcrop of melange to the north. It is our observation, however, that there is a limit of a few meters to the size of these blocks that are clearly identifiable as olistoliths. Truncated bedding, slickensides and other features characteristic of ramp-flat thrust geometry can be seen in this outcrop. The present attitude inferred for the Taconic Frontal Thrust (about 10° east dip) and the steep east dip of these limestone-shale imbricate slices are consistent with their identification as duplex structures. Their attitude is not consistent with a model of tabular olistolithic slabs lying in the bedding orientation.

STOP 7. Boss Hogg's Quarry
Marked "H" on Fig. 9. Permission must be obtained from the owner to visit this locality.
The quarry exposes part of the early Ordovician Providence Island Formation, mainly dolostones with some limestone, not far below the overlying Middle Ordovician limestones (Middlebury) that outcrop to the east (see Fig. 9). The purpose of this stop is to see the structural condition of carbonates within the areally extensive thrust sheets that exist at this latitude between the Frontal Thrust of the Taconic Allochthon and the autochthonous shelf strata. On the south side of the entrance to the quarry a close synformal fold displays well-developed solution cleavage and marked changes in thickness from the short, west-dipping limb to the long, east-dipping limb due to more homogeneously distributed ductile shape change. A complementary antiform is exposed on the north side of the entrance linked to a synform that trends along the northeast face of the quarry. A wrench fault passing through the quarry entrance must offset the fold hinges in a left-lateral sense. The contrast between the substantial ductile strain shown in this outcrop and the lack of such features at Stop 1b in the autochthon is a reflection of the thrust translation of these carbonates and deformation during active movement on lower thrusts. The cleavage at this stop is roughly parallel with that in Taconic rocks exposed to the east. However, this does not necessarily make the cleavages the same age; evidence exists to suggest that they are not, and that the Taconic rocks were cleaved and folded before emplacement over this portion of the shelf carbonate terrane.

STOP 8. Scotch Hill syncline at Glen Lake.
Permission must be obtained from the owner (in the house across the road). NO HAMMERS ALLOWED. Location shown on Fig. 1.
This outcrop exposes early Ordovician strata of the Poultney Formation, probably about the same age as the carbonates of Stop 7, but a very different facies deposited in deep marine conditions on the continental rise. These rocks consist of green mudrock (slate) alternating with thinner laminated layers of fine sand to silt size arenites and quartzites that are interpreted as contourite deposits, and black/gray mudrock (slate) laminae. The black mudrock layers are probably pelagic; the green are likely mud contourites. The syncline exposed here is the single major hinge of a fold that is in a set with wavelengths of the order of 1 to 3 km and amplitudes of similar amount. The folds are tight to near isoclinal in form. This outcrop does not give the impression that the folds are this tight since the full transition to the fold limb bedding attitudes, particularly on the overturned limb, are not seen in this exposure. This particular fold can be traced north for 3 km and south for 8 km from this place; another single fold in this set in the northern Taconics can be traced for at least 50 km along its axis, characteristic of their subhorizontal to gentle plunges. The overturned nature of this fold, with its moderately east-dipping axial surface and near-axial planar cleavage is also typical of the structure of the low Taconics (Giddings Brook Slice). In detail, small parasitic folds in the quartzites in this outcrop can be seen to be transected by the slaty cleavage, suggesting that buckling of thin layers in response to shortening took place, as is usually the case, before thicker composite layers that generate longer wavelength folds. Thus the cleavage may be axial planar to the large-scale folds but not to the smaller ones. Examples of cleavage refraction can also be seen, and cleavage parallel quartz veins (? post-cleavage) are also present. We emphasize the coherent ductile deformation seen in this outcrop, characteristic of all the western Taconics in the northern part of the Allochthon. In our view it does not support the idea of the emplacement of the Allochthon as a gravity slide of unconsolidated sediments. Comparison of structures here with those in the thrusted carbonates (Stop 7) and at the western edge of the Allochthon (Stop 3) are consistent only with thrust emplacement of coherent, consolidated rock, undergoing related ductile deformation (folding and cleavage formation) at different times in different places during the overall assembly of the thrust sheets.

STOP 9. Shelf carbonate duplex
Shelf carbonate duplex beneath the Taconic Frontal Thrust at Bald Mountain, N.Y. Location given in Figs. 1 and 10.
Bald Mtn. has been a perennial favorite for stops in field guide books of eastern New York, and several excellent descriptions of the locality are available in the older literature (Walcott, 1888; Ruedemann, 1914) More recent discussions can be found in Platt (1960), Sanders, et al. (1961), Zen (1967), Bosworth (1980) and Rowley and Kidd (1982).
We have intentionally placed the Bald Mtn. quarries at the end of our trip, despite their proximity to Saratoga Springs. We have been emphasizing processes related to frontal imbrication, multiple generations of thrusting and the formation of duplexes throughout the day. We feel that the examples we have presented are fairly convincing. Bald Mtn., however, is shrouded with historical overtones, and is also exceedingly complex. The general picture is quite clear: the uppermost portions of the quarries are composed of allochthonous Taconic lithologies, these overly a thin zone of phacoidally cleaved shales, which in turn overly discontinuous masses of shelf carbonate (some quite large) and more phacoidally cleaved shale. But the details are not so clear. Are the carbonate blocks fault slivers, or are they olistoliths within a large-scale sedimentary slump mass, subsequently overridden by the Taconic thrust sheets (Rodgers, 1952; Rodgers and Fisher, 1969)?
We recognize some internal order in the disposition of lithologies in the area of the Bald Mtn. carbonates, with similar lithologies aligned along strike (Fig. 10). Several of the carbonate blocks are probably hundreds of meters in length, not unlike the Chazyan sliver on the Mettawee River (Stop 5). As at Stops 5 and 6, small rounded cobbles of limestone (in this case) within the phacoidally cleaved shale zones may in fact be olistoliths, probably derived at subaqueously emergent fault scarps from the main masses of carbonate themselves (Rowley and Kidd, 1982; Bosworth and Vollmer, 1981). However, we again feel that the structure at Bald Mtn. can reasonably be interpreted as a fault duplex (Fig. 11), as was first proposed by Ruedemann (1932, p. 134). We encourage all participants to share their thoughts with the rest of the group!
A regional compilation of presently identified structures believed to be associated with the Taconic Frontal Thrust System (youngest Taconian deformation) is presented in Fig. 12.

A3: TRI-CORN GEOLOGY THE GEOLOGY, HISTORY, AND ENVIRONMENTAL PROBLEMS OF THE UPPER HUDSON CHAMPLAIN VALLEY
Anson S. Piper
Adirondack Community College
Introduction
The region of the upper Hudson-Champlain valleys provides an excellent locale for the teaching of introductory geology courses. In addition to the desired examples of geologic phenomena there are ample opportunities to relate geology and human activities past and present and areas where various field methods may be used to solve very simple problems. It is the purpose of this trip to tour the area from Saratoga Battlefield north to Ticonderoga, view points of geologic, historic and environmental interest and to try to relate them one way or another together.

A3: TRI-CORN GEOLOGY THE GEOLOGY, HISTORY, AND ENVIRONMENTAL PROBLEMS OF THE UPPER HUDSON CHAMPLAIN VALLEY

STOP 1. Saratoga National Park Visitors Center
The battles fought here were, collectively, one of the most decisive actions during the course of North American history. They represented the climax of a complex, three-pronged campaign, which, had it succeeded, would have cut the rebelling colonies in two, probably winning the war for the British. The American victory assured recognition by France and subsequently to the alliance.
The choice of ground was made by the Americans, who drew up their lines overlooking a narrow defile along the Hudson. Entrenchments were dug along Bemis Heights under the direction of Col. Kosciusko. The area was sparsely settled, with farms in scattered clearings, connected by wagon roads through the forest. Where the roads traversed sand, they were difficult to move over with heavy loads. Where they traversed clay, they were impossible when wet, and if rutted, nearly the same until beaten down. Burgoyne, with his heavy train of baggage and artillery, was forced to descend the river using batteaus for his supplies while his men trooped along the parallel road. He had crossed to the western side just north of present day Schuylerville (Saratoga). The American defenses, therefore, commanded his route along the river and extended westward to prevent his flanking them.

This is the "280 ft." level of proglacial Lake Quaker Springs.

The "250 ft." level of Lake Coveville.

Coveville Plunge Basin.
Drainage from the Ballston Channel combined with waters of the Kayderosseras dropped into the almost river-like Lake Fort Ann.

Site of Ft. Hardy, Where British grounded arms, is on the flood plain to the right.

Burgoyne's final positions.

STOP 2. Stark's Knob.
Pull off road and park. Hike up road leading west past the knob. THE EXACT OWNERSHIP OF THIS SITE IS, AT THE TIME OF PUBLICATION, UNKNOWN, BUT IT IS NO LONGER THE PROPERTY OF THE STATE OF NEW YORK, HAVING BEEN DEEDED TO THE TOWN OF NORTHUMBERLAND. THE TOWN IS THOUGHT TO HAVE DISPOSED OF IT TO A PRIVATE INDIVIDUAL, WHO DENIES THAT IT IS HIS. AS THE RESULT OF REPEATED INTRUSION ONTO HIS ADJOINING LAND, HE HAS MADE IT KNOWN THAT HE WILL HAVE ALL PERSONS WHO STRAY ON TO HIS PROPERTY ARRESTED.
IT IS THEREFORE IMPORTANT THAT VISITORS STAY ON THE TWO ACCESS PATHS TO THE SITE AND AVOID CROSSING THE OLD FENCE LINES.
The Knob is named for General Stark. who placed his artillery atop of it in the final days of the campaign, thus blocking the withdrawal of the British up the Hudson River and along its western bank. The knob has been formed by the differential erosion of the soft black shale from around the more resistant basalt of the pillow lava. Both the shale and the pillow lava are part of an overthrust block of Ordovician rock displaced a considerable distance from the east during the Taconic events.
The material between the pillows contains fragments of the carbonates through which the lava appears to have passed on the way to the surface. The pillows themselves, have a chilled surface and are laced with quartz and calcite filled fractures. Several small faults cut down through the quarry face and water moving along these has formed a small spring at the base near the large pine tree. The basalt was quarried for "road metal" prior to its acquistition by the state.

Fort Miller
The fort was built on the opposite side of the river, to protect the portage around rapids or a small falls on the river. It was a wood stockaded "star fort".

The old Champlain Canal on the right.
This old canal wanders along, following the contours in order to reduce the number of locks. Rt. 4 crosses its path.

Exposure of black shale and sandstone in a near vertical attitude.
A few graptolites have been collected here dating it as part of the Taconic over-thrust.

Bridge over the Champlain Canal.
The Hudson River is seen below the locks. This water barrier was nonexistent during the 18th century so that it was easier to build the military road down this side of the river.

The Fort House Museum
(Time permitting, a brief stop.) This house was built prior to the revolution of materials said to have been scavenged from the buildings at the fort. There is an old, but never-the-less good, model of Fort Edward - a typical earth and timber fort.

Bridge over Fort Edward Creek with an old canal aqueduct over it to the right.

Site of Fort Edward
All that remains of this, the largest British military installation in North America prior to 1800, is a small portion of the moat. It was essentially a three bastioned earth and timber fort, built over a period of two years on the site of earlier Fort Nickolson. Additional works were built on "Roger's Island" the home base of Roger's Rangers. The fort was never besieged or defended except against small raiding parties. It was placed here at a position of great strategic importance, but like Ticonderoga, it was overlooked by high ground making it indefensible. Seven blockhouses were placed around it to cover the weaknesses in its approaches. This point is the furthest extent of the navigable waters of the Hudson and the southern end of the portages to Lakes George and Champlain.

This canal was completely plugged following the removal of the power dam.

STOP 3. Roger's Island
In the early 1970's, the Niagara-Mohawk Power Corp. received clearance to remove a small power dam located just north of the island. The volume of sediment entrapped behind the dam was greatly underestimated and the P.C.B. content was not recognized as a hazard and ignored. When the spring flood occurred, a huge volume of P.C.B. laden sediment washed down stream, leaving the north channel plugged and the south channel nearly so. This resulted in three major problems: the navigational channels were plugged here and downstream, P.C.B 's entrapped in the sediment were distributed with them and raw sewage from the Village of Fort Edward was piled up atop of the plugged channel.
The New York State Department of Transportation dredged out the channels and stored the material at the DOT sites on Roger's Island and on the Town of Moreau side of the river. It was an annual event for several years until the bulk of the sediment was washed out and the nature of the P.C.B. problem "surfaced". During the last dredging, the P.C.B. threat, having been recognized, workers were required to wear dust masks and the material was encapsulated, the previous dumpsites were covered with a temporary cap of clay. An unexcavated archeological site was buried in the, process.

STOP 4. D.O.T. Site
This is an encapsulated dump site for the P.C.B. laden sediments dredged from the Hudson River at Roger's Island. The debris was placed in a clay lined pit and then covered again with clay. It is a temporary disposal site.

Marker on left for the McCrae House
After making turn note marker on left for the McCrae House where Jane McCrae was taken by Indians. Rt. 4 approximately follows the military road to Lakes George and Champlain.

The approximate site of the killing of Jane McCrae.
A blockhouse was situated about where the school athletic field is. The road is climbing up onto the sand delta deposited into Lake Coveville.

STOP 5. Fort Edward General Electric Plant & Union Cemetery
This is one of two General Electric plants locally which manufacture electrical components (capacitors chiefly) previously using P.C.B.'s. To the right rear, next to the Grand Union Store, is an Agway Farm Store, which sells pesticides and herbicides to local farmers. Union Cemetery, located to right, is the burial place of several persons of note, including Jane McCrae, Duncan Campbell and Tobert Cochran.
The location is atop a sand delta (Lake Coveville) some 15 to 20 feet thick overlying a shale which crests under the General Electric Plant and slopes away toward the river to the southwest and the Champlain Canal to the northeast.
Two groundwater problems have developed here, the first involving agricultural chemicals and the second, P.C.B.'s and T.C.E.. Most of the local dwellings have their own waterwells, some of which have become polluted by either or both types of chemicals. The pesticides and herbicides have shown up in wells on Putnam Avenue and Ethan Allen Street southeast of the Agway Store and extend as far as Burgoyne Avenue. The seemingly harmless act of washing trucks appears to have been the cause of this problem. One more good example of why ordinary people need a better education in geology. The P.C.B. - T.C.E. problem is more complex. Both chemicals were uses extensively at the General Electric Plant and the deliberate and accidental spills over many years have gradually polluted the groundwater about the buildings. In addition, some individuals have dumped the industrial chemicals at their homes where they have been salvaging materials or using T.C.E. on their own projects. Wells along adjoining streets have been abandoned and these homes have been connected to municipal water systems, the cost being borne by G.E. There is very extensive litigation involved in these cases and little information can be gained from the parties involved.

Ciba-Geigy Plant and wastewater treatment plant.
Prior to the construction of the treatment plant, waste water containing heavy metals was discharged into the Hudson adding to the pollution from the paper mills upstream. Following the imposition of environmental controls, this installation was built to separate the toxic components from the water which is returned to the river cleaner (supposedly) than when it is taken out. The solids are then hauled to the Queensbury Landfill where they are placed in a disposal basin.
The road climbs up onto another sand deposit, this one is probably related to Lake Quaker Springs.
Across the river to your rear, is the Glens Falls Cement Quarry showing the thickness of the sand overlying the carbonates. The cement plant was the center of an air pollution study done by Adirondack Community College students many years ago. The study pinpointed the plant as a major source of particulate matter in the air and with the passage of clean air regulations, the old stack was replaced with one containing "scrubbers" and the problem was essentially solved. The Glens Falls Limestone quarried here was previously produced from tunnels underlying the Village of South Glens Falls.

Dix Avenue is following the route of the old military road to Lake George.
It skirted the low area through which we have just passed, and swung west and then north to avoid the swamp through which Quaker Road passes.

Prospective Peat Farm
Peat deposits have formed in swamps which developed on Lake Albany clay which sealed the underlying limestone. The development is stalled pending a decision related to the Wetlands Protection Act.

You are now entering "New France"
You are now entering "New France" as you cross Halfway Brook and enter the St. Lawrence drainage basin.

Brief Pause - Adirondack Community College Quarry.
This exposure of Ordovician, Beekmantown Carbonates, contains a breccia, (fault or collapse ?) some small cephalopods and burrows of a sort. The campus is located on a downfaulted block (a graben) with a fault running approximately across Bay Road and another somewhere between the rear of the buildings and the next ridge to the east. Other structures are suspected because of the change in the attitude of the rocks in the several outcrops on campus. A small fault with a 2 inch displacement has been found. In addition, there is an exposure with enlarged solution joints, perhaps formed during the post-glacial interval while Lake Albany was draining. The soils on campus are lake clays (some varves were found in the building excavations) and to the west and north, is the kame and esker complex.

The road climbs up onto the kame and esker complex.
Blind Rock was a locality where native war parties often took prisoners for torture.

Round Pond and Paradise Beach.
A kettle lake with an esker on each side at the far end. The one extending along the north side continues along the right side of the road.

This is near the epicenter of a number of very small quakes
This is near the epicenter of a number of very small 'quakes (.5 Richter or less) which were detected during a study done by the N.Y.S.G.S. Rt. 9 passes over 5 Mile Run, the site of several ambuscades, just in front of the Great Escape Amusement Park! The low area on the right, past the park is an extension of Glen Lake, an iceblock lake .

Kame terrace capped by Lake Albany sands.

STOP 6. Col. William's Ambush
PARK ALONG ROAD SIDES WHERE IT IS SAFE. THIS IS A DANGEROUS SITE.
The outcrop is on the west side of the road and is extremely hazardous because of traffic. The bedrock is Precambrian (Grenville) Gneiss and is cut by several nearly strike-slip faults running parallel to the road. At one point a small dike is cut into three sections by the faulting. Prior to the widening of the road, there was a fine, fluted, slickensided surface exposed. French Mt. opposite, is a horst.
The military road passed below the present road and this was the site of the French ambuscade of the Provincials and Iroquois, known as "The Bloody Morning Scout". Col. Ephraim Williams, whose estate founded Williams College, was killed standing on a glacial boulder, while old "King" Hendrick toppled from his horse and was bayoneted. The colonials and Mohawks successfully withdrew from "Rocky Gulch" to Lake George, leaving about 100 casulties behind.

Bloody Pond, a kettle lake and the scene of two skirmishes.

STOP 7. Fort George And Battlefield
Here is another exposure of Ordovician, Beekmantown carbonates, dipping about 5° northeast and lying between two mountains of precambrian rock. This presents an opportunity for solving a very simple structural problem Three responses are usually evoked from beginning students when asked to explain it:
1. The rocks were derived from the older rocks and deposited here.
2. They were downfolded into the valley form.
3. They were downfaulted.
The first choice is eliminated by the character of the sediment, and the others require further information to be gained at the next stop.
The carbonates were first used to build the stone bastion of Fort George, which was built following the Battle of Lake George. The rocks provided both the building stones and the mortar to hold them in place. The present structure has been partially restored.
The battle here followed the Bloody Morning Scout, Dieskau, the French commander launched a series of assaults on Johnson's camp and was repulsed with heavy losses. Both officers were wounded and Dieskau taken prisoner. The French and their allies fled to Bloody Pond to loot the packs of the men killed there earlier, where a relief column of over 600 men from Fort Edward caught them disorganized and scattered the survivors.
After the battle, Fort William Henry was finished on the sand terrace overlooking the lake. The fort was built of timbercribs filled with sand from the moat. The main gate was on the south side, and a stockaded area on the north. The choice was poor in the sense that the sand, being easy to dig, allowed Montcalm to advance his saps and parallels very quickly when he laid seige two years later in 1757. His artillery quickly reduced one bastion. The sand pouring out through broken timbers caused it to collapse and the fort surrendered. The attack on the unarmed British prisoners following the surrender is a matter of historic record.

STOP 8. Exposure of the upper Cambrian Ticonderoga Formation
This exposure of the upper Cambrian Ticonderoga Formation dips gently toward the northeast and consists of mostly sandstone which places it in the upper third of the formation but not at the top which contains some chert. There are ripples and stromatolites present, the latter being in the reddish-brown dolomitic layer at the top of the ledge. The upper surface has been planed smooth by glaciation and the direction of movement has been recorded in striations found there. Visible to the west is an exposure of precambrian rock at the bend in the road. These observations tend to support the hypothesis that the valley floor is a downfaulted block or graben. Further support to the idea comes from the existence of two magnetic anomalies between the two outcrops. (Personal communication from John Mead) A similar relationship between the Precambrian and the carbonates can be seen along the east side of the valley. (Along Rt. 9-L near Crosbyside)

The road follows the trace of the English Brook Fault.

Brief Pause - The English Brook Saprolith
Note: This exposure of deeply weathered rock has been known since the 1930's and has miraculously survived repeated road improvements. Originally, the exposure was topped with two layers of glacial boulders separated by a lake sand. Each spring these came rolling down - some three feet in diameter - to the dismay of the highway department. Their recent removal and the gradual covering of the face in its own debris has greatly altered the appearance of the site. The preservation of the saprolith is thought to be the result of deep weathering along the plane of the fault and the transverse orientation of the fault to the direction of ice movement. This is one of the few such exposures which can be easily seen in New York State.

Note en route: This valley was occupied by Glacial Lake Warrensburg
Note en route: This valley was occupied by Glacial Lake Warrensburg, evidence for which is seen in the numerous sand deposits along its floor. Just short of Milepost 63, the road cuts show precambrian rocks on one side and layered sediments on the other, the road straddling a fault.

Roger's Rock State Park And Campsite.
Named for Roger's Slide thought to be the fault scarp forming the east side of the Lake George graben and the scene of Major Roger's escape from the French and Indians, March 13, 1758.

Ticonderoga Creek - The outlet from Lake George flowing into Champlain

STOP 9. Fort Ticonderoga (Carillon)
This fort is built near if not on the site of Champlain's skirmish with the Iroquois in 1609. Construction was started in 1755 and essentially completed by 1758. Modifications, repairs and improvements continued until the end of the American Revolution, when it was allowed to fall into total disrepair.
The original construction was of earth and timber, later on improved by stone facints. The fort was designed for a small permanent garrison with extensive outworks for a larger "summer" army. The location was poorly chosen, since the works are well within range of seige guns placed on the heights of Mt. Defiance.
The stone fort was built from Ordovician limestone, quarried on the site, and was in total ruin prior to reconstruction. The stone work, weakened by solution and frost action, had collapsed into the moat, and hauled off to build "celler walls" by the post war settlers. The original foundations can be recognized in the walls by their weathered appearance.
Mt. Independence, on the opposite shore, was linked to the fort by a bridge consisting of 22 sunken piers connected by 12' X 50' "pontoons" chained together. The piers still survive in the muddy floor of the lake and are currently being salvaged (?) along with numerous other artifacts of the Revolutionary War.

South Bay, Lake Champlain

Note Rock Falls along road cuts .

STOP 10. The Hudson-Champlain Canal
The canal follows the general path of wood creek which rises near Fort Edward. During the spring of 1984 this area was badly flooded when water backed up behind a coffer dam following a heavy rain. The dam, installed to permit repairs on the canal, was not designed to accommodate the sudden rise of waters and considerable damage was done to the small museum here and other structures.
Historically, the locality was called Skenesborough, after Philip Skene, a prominent Tory. The claim to be the "birthplace of the United States Navy", stems from the fact that Benedict Arnold's fleet was built here, the first continental squadron. Although it was defeated at Valcour Island, the fleet delayed the Burgoyne campaign until the next year. The hull on display here is a survivor of the Battle of Plattsburg Bay, during the War of 1812. A military road was built from here to Fort Edward and later improved by Burgoyne.

This road will follow closely the old military road parallel to Wood Creek.
It travels over the floor of Lake Fort Ann.

Lake Clays On Right - Note Slumping
Champlain Canal Locks on left.

Note: Rockfalls In Road Cut.

Brief Pause - Road Cut In Precambrian Gneiss.
The foliation and some joints in the gneiss dip toward the east so that the road cut intersects or "daylights" them along the west side of the road. In order to reduce the chance of failure along these planes, the threatening blocks have been bolted into place with heavy threaded rods which penetrate into "solid" bedrock.

STOP 11. Unconformity
The base of the Potsdam Sandstone is exposed here in contact with the precambrian gneiss. The basal conglomerate above the unconformity contains many large quartz pebbles here. Additional exposures of the Potsdam may be found by walking down the side road to the left and just past the small valley, climb down over some old concrete slabs to a flat exposure. Graded bedding, crossbedding and ripples can be found here and in the railroad cut. Glacial striations, chatter marks and quarrying faces may also be seen. A commercial building stone quarry across the canal was previously operated and many local houses are built of this rock.

Battle Mt.
A rear guard action was fought here by the Americans fleeing Burgoyne's army. This was one of the first times that the "Stars and Stripes" were flown in battle.

Entering Fort Ann Village
The reconstructed blockhouse (bank) was originally intended for a museum. It is fairly accurately constructed and very close to the actual site of the fort which guarded the crossing of Halfway Brook where it entered Wood Creek. There was a stockade surrounding the blockhouse. Note the use of Potsdam sandstone in several of the older buildings.

Possible route for Burgoyne
Burgoyne's line of march probably followed Route 4, but it is also possible that he did follow this lower route.

Smith's Basin.
On the far side of the canal is an excellent section of Cambrian and Ordovician carbonates described by Donald Fisher in the N.E.I.G.C. Guidebook 61st mtg. 1969. An old limestone quarry and kiln was operated just across the bridge in an exotic block or thrust slice of Orwell and Glens Falls limestone. The basin was an old canal basin and at one time was a fairly large settlement.

Kingsbury Landfill (Closed)
Note also, the Feeder Canal, five "combines" Locks and small house at right of intersection beyond canal.
The Kingsbury Landfill is now probably the chief source of P.C.B.'s entering the Hudson River. Many capacitors were disposed of here and on summer days, their sweet odor can be detected. The P.C.B.'s are leaching out of the site, into the canal and into the Hudson River. Another path is into the groundwater and the lowlands below the site to the river. Current plans call for the capping of the site hopefully sealing it. General Electric has made a major contribution toward the cost, but the remainder must be borne by the local taxpayers.
The feeder canal served two purposes: to move barges to Hudson Falls and Glens Falls and to maintain the water level of the lower section of the canal.
The small house may have been Burgoyne's Headquarters when his army camped here. In any event, it is thought to be one of only two buildings not burned down during Carleton's Raid in 1780.

This is Baker's Falls, the highest falls on the Hudson.
While it is capped by a dam to increase its generating capacity, it is probably due to a fault. The river has cut a deep gorge through the softer shales below the falls.
It was the presence of this falls which caused Fort Edward to be built and the settlement of "Sandy Hill" to develop into the Village of Hudson Falls. The falls and dams upstream provided the water power for the early mills and later the hydroelectric generating plants, ultimately leading to the locating of the General Electric plants and the P.C.B. problem. It was also found that some P.C.B. was used to produce carbon paper upstream at a paper mill.

Caputo Dumpsite.
This site which is located along the right side of the road, in back of the houses was used to dispose of industrial wastes from the General Electric Company from about 1958 to 1970. It was an open pit into which barrels were placed, filled with waste, P.C.B.'s and T.C.E. The subsurface consists of glacial sands and lake clays overlying bedrock. The watertable is about 25 feet down. ENCON. well information indicates the following:
0 - 70 feet Medium to fine sand
70 - 95 feet Fine to very fine sand with silt lenses 1/8 to 1/2 " thick.
95 - 100 feet Fine sand - clay lenses with brown varves
100 feet + Gray clay and silt lenses over bedrock.
The site has been enclosed by 1600' slurry wall 100 feet deep and three feet thick in an attempt to contain the leakage. The slurry consists of 70% soil, 28% native clay and 2% bentonite. The whole is capped to shed water. The P.C.B.'s appear to be more or less contained and saturate the soil above the watertable. The T.C.E.'s on the other-hand appear to have sunk down rapidly to about 70 feet. A plume has formed between 45 and 70 feet, spread out about one mile down gradient in 2-2.5 years. The water at the watertable appears clean as does the water below 70 feet, thus the plume appears to be moving toward the southeast in a sheet about 25 feet thick at a present rate of eight feet per day.
Many residential waterwells have already been polluted and some properties in close proximity are claiming unsafe levels of vapors within the structures. Because of pending litigation, it is difficult to obtain specific and valid information from some parties. The plume which is moving toward the Fort Edward water supply has shown up in a stream feeding it. A system of aeriating the water has been installed which allows the T.C.E. to dissipate. Additional P.C.B.'s were sprayed along the Fort Edward road to settle dust and this has recently been removed by scooping up the contaminated soil and placing it at the Caputo Site where it is to be encapsulated.

A4: THE MINERALOGY OF SARATOGA COUNTY, NEW YORK
JOHN J. THOMAS AND JENNIFER A. RICHARDS
Skidmore College
Saratoga Springs, NY 12866
INTRODUCTION
Saratoga County includes within its boundaries the Adirondack Highlands and the Hudson and Mohawk Lowlands. The rock types range from the Precambrian Grenvillian granulites of the Adirondacks, located in the northwest quadrant of the county, through Cambro-Ordovician carbonate and clastic rocks. While the area is predominantly covered by Pleistocene glacial till and sediments of glacial Lake Albany, scattered bedrock exposures afford excellent mineral collecting.
Several of the county's most famous mineral collecting localities are either closed to the public or have been lost. An example of the former is the Gailor Quarry in Saratoga Springs. While the quarry is inactive, the faces have become very unstable and because of collector abuses, the owners no longer allow access. An example of a lost locality is the collection site for chrysoberyl, for which Saratoga County is famous.
The original description of the quarry measures its location from Route 9. Since the publication of the location, routes have been renumbered and relocated.
All of the localities that are listed in this guidebook are on private property and require special permission from the landowner to visit.
PURPOSE
The purpose of this field trip is to examine a variety of mining and mineral localities in Saratoga County that are typical of this area and the Southeast Adirondacks in general. The minerals available in large quantity are fairly common, but interesting in terms of size and development. The quarries visited will include a graphite mine and several pegmatites. Opportunities exist to collect a variety of minerals, observe the relationships between them, to study the mines' relationships with the country rock, and to see late 19th and early 20th century mining techniques.

A4: THE MINERALOGY OF SARATOGA COUNTY, NEW YORK

STOP 1. Wilton Graphite Mine
The graphite mine is located to the west of US Route 9. Enter the woods directly opposite Worth Road. There you will find a dirt road leading up the side of the mountain. The following measurements are taken starting from the west edge of US 9. All measurements are in feet.
467 | The foundation of a former building on the left.
1533 | On the right is the foundation of the boarding house for the mine.
1756 | On the left is the foundation for the loading bins. Horse teams took the refined graphite from here to the railroad.
1890 | On the left is the waste water dam and settling pond, even then a matter of controversy. Each year the pond was allowed to flush itself out into the fields below. If you follow the stream valley 1,000 feet upstream, on the right you will find the foundations of the concentrating plant which originally consisted of five levels. The original turbines are still here. There was also a steam generating plant here that supplied power for the mill and mine.
2725 | Stream crossing. Foundations on the left are for the upper level of the mill. A narrow guage railroad serviced the mine from here.
2840 | A fork in the road, take the road to the right.
2935 | The cut on the right and left was a drainage ditch for the underground mine and connects with it.
2890 | The entrance to the underground mine, known as the mine, on the left.
3411 | Follow the main road
3591 | Another drainage ditch.
3833 | The trail from the Wilton-Greenfield Road enters on the right.
3982 | On the left is the large open mine, known as the quarry. Water fills the west end.
4326 | The road is now a trail. The end of the quarry.
The following description is taken from the Adirondack Graphite Deposits by H. L. Alling (1917).
The property was first opened about 1910 by the Saratoga Graphite Company which worked it in a small way for two years. After a few years the mine was taken over by the Graphite Products Corporation which enlarged the plant and the mine and worked it until about 1922.
The original mine is 22 by 30 meters and was worked only by the Saratoga Graphite Company. The Graphite Products workings consist of the mine and the quarry. The mine extends 115 meters along strike, inclines 38-42 degrees south. A number of openings have been driven down dip meeting two parallel horizontal drifts. The quarry is an open pit mine extending eastwest, 125 by 30 meters. Now water filled, in 1917 it was 10 meters deep.
The rock containing the graphite is described as a quartz schist and occurs in two outcrops, the mine and the quarry, repeated by faulting. From Alling (1917, p. 106) describing a south to north section (fig. 1), " ... a serpentinous limestone forms the bed of the brook .. , next rock to the north is a para-amphibolite grading into the quartzite ... injected and saturated by Laurentian Granite a lenticular mass of metagabbro ... a siliceous limestone ... beneath the limestone the graphite schist shot through with 'pegamatitic material which forms knots and stringers' a fault parallel to bedding occurs here ... a gap in the cross section Pegamatite, quartzite, and metagabbro ... a reddish garnetiferous quartzfeldspar para-gneiss ... The rocks here are faulted and penetrated by pegmatite ... It is not possible to name with certainly the rock forming the floor of the quarry ... The north end of the section ends in a limestone." The section as described correlates with the Spring Hill Pond Formation of the southeast Adirondacks. A diabase dike 10 meters wide outcrops just west of the mine. A second dike, 25 cm. wide, outcrops west of the finishing mill.
The ore is similar to the American, Hague, Flake and Hooper ores. Graphite content is 7-8% all flakes are less than a millimeter in diameter. The outcrop is badly weathered, but at the bottom of the inclines in the mine is in better condition.
The mining technique was primitive by any standard consisting of steam drilling, hauling the ore out of the mines with donkey engines, and loading it into wagons. Teams hauled the ore to the narrow gauge mine cars which took it directly to the concentration mill. The usual Adirondack'milling practice of crushing, stamping, buddling, screening and drying was used. The finishing mill used Hooper pneumatic jigs which prepared the graphite for market.
Minerals and Rocks: Apatite; Diabase; Graphite; Pegmatite; Phlogopite; Quartz schist

STOP 2. Black Pond Pegmatite
The Black Pond Pegmatites, unreported in the literature, were mined in the early twentieth century for abrasives used in Bon Ami Cleanser. The description of these bodies is taken from a 1984 field report by Tara Mandeville of Skidmore College.
Black Pond is one mile down the logging road from its intersection with Lincoln Mountain Road. The pegmatites are hard to spot from this direction. Directions for finding the bodies follows, the distances are in feet:
3450 - First sign of crushed pegmatite in the road.
4015 - Pegmatite (Ml) on the west side of the road.
4150 - Road on the west goes to the big pit (M2).
4365 - Pit on the west side of the road (M4).
4590 - Side road to the east (M6).
5110 - Black Pond.
As one approaches the outcrops from Lincoln Mountain Road (fig. 2), the first evidence of the outcrops is a tailings pile (Ti) adjacent to a small mine pit, Ml (approximately 4.6 m. long by 4.6 m. wide by 2.4 m. deep). The tailings are composed of feldspar, quartz and biotite. The pit contains several small pegmatites varying from pure feldspar to quartz-rich pegmatite with large crystals of biotite. The country rock is a biotite-quartz-feldspar gneiss.
The largest pit in the area (M2) is 30 m. x 12 m. x 9 m and is partially water filled. The coarse grainedfeldspar-quartz-biotite pegmatite is discordant to the 280,35W striking, medium grained, biotite-quartz-feldspar gneiss country rock.
Pit #3 (M3), 6 m. x 6 m. x 3 m., contains several smaller pegmatites that are partially concordant and rich in quartz. The surrounding fine to coarse grained gneiss contains abundant biotite. The adjacent tailings pile (T2) includes feldspar and rose and smokey quartz, but little biotite.
A very large tailings pile (T3) lies just south of Mine #3 and is probably the tailings from Mine #2. The tailings are dominantly country rock with some pegmatite. Large crystals of tourmaline were found in this dump.
Further south along the logging road a small overgrown trail enters from the east. Opposite this trail is Pit M4. This is a small quartz-feldspar pegmatite interrupted by a small lens of biotite-rich gneiss. At the entrance to the path is a small tailings pile (T4). Further up the path is a feldspar, quartz, biotite pegmatite mine (Ms) 6 m. x 9 m. x 6 m.
South along the main logging road toward Black Pond, a side road enters from the east. Along this road are feldspar-rich tailings (T5), several test pits containing quartzite (Q), and Mine #6 (6 x 3 x 2 m.) which is another feldspar, quartz, biotite pegmatite.
Along the northwest corner of Black Pond is the last of the pegmatites (M7). Here is a small discordant pegmatite in a gneiss which contains coarse grained feldspar and finer grained quartz and biotite. The tailings (T6) associated with this mine contain feldspar, rose and smokey quartz and biotite.
Minerals and Rocks: Rose quartz; Smokey quartz; Tourmaline; Biotite; Rose quartz graphic granite; K-feldspar; Graphic granite; Granitic gneiss

STOP 3. Mount Anthony West Pegmatite
The following description is taken from Geology of the Luzerne Quadrangle by W. J. Miller (1923). The pegmatite has not been described in detail, but is referred to several times.
Miller (1923) describes west of Mounth Anthony a terrane of metagabbro-granite rocks where many small pegmatites without sharp borders cut across the foliation. Magnetite, in amounts to be classed as ores, in 1923, is observed associated with granite, pegmatite, and metagabbro. This stop has been selected for this magnetite-pegmatite association. The magnetite is always in moderately coarse grained, gray pegmatite in masses up to 2 or more centimeters across. The country rock is a garnetiferous Grenville gneiss or amphibolite. Mines in this area were worked 90-100 years ago and some ore was shipped. Also, attempts were made to use the white feldspar in the pegmatites.
Minerals and Rocks: Pegmatite; Magnetite; Country rock

STOP 4. Overlook Quarry
The following map (fig. 3) and description are taken from Tan (1966). Miller (1923) describes the Overlook Quarry as producing pottery feldspar as late as 1920. pegmatites.
The country rocks are granitic gneiss and magnetite-bearing metagabbro. pegmatites.
The border and wall zone (I) is in sharp contact with the country rock. The border zone is difficult to distinguish from the wall zone. The border zone is fine grained in places. A lense rich in andesine which occurs at the west margin of the ore body is interpreted by Tan to represent an incompletely developed border zone, although a segregation (replacement) origin is possible. In the border and wall zone, both pink and white potassium feldspars are found and a coarse graphic texture is common. Associated biotite plates are more than 1 m. in diameter. pegmatites.
The intermediate zone (II) is mainly white potassium feldspar crystals up to 1 m. across, with subordinate amounts of quartz, plagioclase, and large black tourmaline crystals which reach lengths of 15 cm. or more. pegmatites.
The core zone (III) is rose quartz and crosscuts the intermediate zone (II). pegmatites.
Minerals and Rocks: Albite; Allanite; Magnetite; Manganoaptite; Oligoclase; Orthoclase; Rose quartz; Smokey quartz; Thorite; Tourmaline; Zircon (Cyrtolite); Graphic Granite; Andesine; Biotite; Microcline; Monazite; Plagioclase; Polyclase; Quartz var.; Sericite; Uranite; Uranothorite; Manganoan-flourapatite; Country rock

STOP 5. Batchellerville Quarry
The following description is taken from Tan (1966). The Batchellerville deposits can be reached by a logging road at the rear of the mobile home park east of Saratoga County Route 7. The outcrops consist of two pegmatite bodies (fig. 4) reported by Newland and Hartnagel (1939) and six more bodies found by Tan (1966).
The bodies were worked by the Claspka Mining Company in 1906 and were still mined in 1916 and 1921. Mining was for microcline for the ceramic industry. Most of the pits show only wall rock with the central productive portions, the pegmatite, having been removed. The small size of the mining pits indicates that the production was never great. The deposits are famous for having yielded the largest beryl reported in the state, 69 cm. long and 25 cm. in diameter. The muscovite contains too many iron inclusions for electrical uses.
In the lower pit, the contact between the pegmatite body and the wall is sharp. On the south wall the pegmatite body lies in a gently folded anticline plunging 30 degrees toward the south. Biotite, uraninite, pink and pale green apatite, and bladed allanite are found along the vertical northwest wall of the pit. In the wall zone (III), scrap muscovite (about 1/4 to 1 cm. in width) appears. White graphic potassium feldspar with parallel short quartz rods is exposed in the south wall. The biotite is partly chloritized. Subhedral high-temperature quartz is intergrown with muscovite. Pyrite and low-temperature quartz crystals, with prism faces, are found in small vugs about an inch across. The intermediate zone (III) consists of giant white microcline about 1 m. long, muscovite columns, and small amount of quartz. The quartz core (IV) near its upper margin contains columnar muscovite crystals with lengths of 15 to 25 cm. Veinlets of quartz extend outward from the core and invade the microcline, but no sign of argillization or sericitization is observed.

A5: CORRELATION OF PUNCTUATED AGGRADATIONAL CYCLES, HELDERBERG GROUP, BETWEEN SCHOHARIE AND THACHER PARK
PETER W. GOODWIN, E.J. ANDERSON, LAWRENCE J. SARAKA, WILLIAM M. GOODMAN
Temple University
INTRODUCTION
The purpose of this trip is to instruct participants in the field application of the PAC Hypothesis. Specific objectives include:
1. demonstration of criteria for recognition of PACs in shallow - water carbonate facies of the Manlius Formation;
2. construction of a PAC column by participants at Schoharie N.Y. in the Manlius Formation;
3. observation and evaluation of the stratigraphic section of the Manlius Formation at Thacher Park from an episodic perspective and comparison of those observations to a PAC column constructed by the trip leaders and
4. discussion of the methods, problems and implications of correlation of Manlius PACs between the Thacher Park and Schoharie sections.

A5: CORRELATION OF PUNCTUATED AGGRADATIONAL CYCLES, HELDERBERG GROUP, BETWEEN SCHOHARIE AND THACHER PARK

Large road cut in lower Helderberg Group (STOP 1) on south side of 1-88.

Road cuts in Kalkberg, New Scotland and Becraft fms
Small road cut in Kalkberg Formation on north side of 1-88; large road cut on south side in New Scotland and Becraft Formations.

Small road cut on south side of 1-88 in upper Becraft Oriskany and Esopus Formations.

STOP 1. Brayman, Rondout Manlius and Coeymans Formations
The Cobleskill-Rondout-Manlius interval (85-feet thick) is completely divisible into 13 PACs (fig. 4). The 5 Cobleskill-Rondout PACs comprise a sequence of peritidal cycles initiated and ended by large punctuation events (see water-depth curve). The first of these events followed a sea-level fall which produced the unconformity with the Brayman Shale. After the deposition of 5 PACs, a second large event terminated tidal-flat deposition and initiated a sequence of basically subtidal PACs in the lower Thacher Member of the Manlius Formation. Thus each of these major punctuation events is marked by the introduction of significantly different facies.
Within the sequence of 8 Manlius PACs the boundary between PAC 5 and PAC 6 is unique. At this boundary the upper part of PAC 5 is marked by a laminated cryptalgal crust on a scalloped surface, features which suggest subaerial exposure and erosion resulting from a minor sea-level fall. This surface is a widespread marker horizon traceable throughout the Hudson Valley. The subsequent sea-level rise created water depths sufficient to produce the subtidal bioturbated stromatoporoid-bearing limestones of PAC 6. Another significant punctuation event resulted in even greater water depth and the diversely fossiliferous subtidal facies of PAC 7. PAC 8 is like 7 but is truncated by an unconformity.
The Manlius-Coeymans boundary is a surface with a complex history. At Schoharie, at the top of Manlius PAC 8 (fig. 4), it appears to be a normal PAC boundary marking a major punctuation event which introduced facies very different from Manlius facies below. However, correlation of PACs to the east and south indicate progressive erosion and elimination of PAC 8, 7 and 6 in the Hudson Valley as a result of differential uplift. This erosional surface was then inundated by a sea-level rise which initiated Coeymans deposition throughout the area.
Thus the Cobleskill-Rondout-Manlius interval at Schoharie represents episodic stratigraphic accumulation in response to a complex history of small-scale sea-level fluctuations including 3 sea-level falls and 14 sea-level rises. That each of these events is trUly allogenic and probably eustatic is suggested by correlating each PAC and PAC boundary between Schoharie and Thacher Park (fig. 5).

Quarry in the ManliusCoeymans interval
Quarry in the ManliusCoeymans interval on the south side of road (Rickard Locality 67).

STOP 2. Indian Ladder Staircase, John B. Thacher State Park.
At this locality the Rondout-Manlius-interval consists of 9 PACs, 2 in the Rondout and 7 in the Manlius (fig. 5). The smaller number of Roundout PACs relative to Stop 1 reflects the episodic overstepping of the land mass which was topographically higher at Thacher Park than at Schoharie. Manlius PAC 8 at Thacher Park is absent as a result of pre-Coeymans erosion. Correlation of PACs between the two localities was accomplished by matching unique facies and major facies changes produced by punctuation events. When the columns are correlated by these methods, the number of PACs between major punctuation events is the same at each locality.
Within the Manlius Formation PACs generally consist of facies representing more restricted paleoenvironments than those at Schoharie. For example, PACs 3 and 5 at Thacher Park are capped by a significant thickness of cryptalgal laminites representing aggradation to sea-level. At Schoharie PACs 3 and 5 are capped by shallow subtidal facies reflecting the presence of persistently deeper and less restricted environments at this locality.
Patterns of punctuation events are similar at both localities as interpreted by comparision of facies changes at PAC boundaries. For example a major punctuation event introduced Manlius facies (PAC 1) at both localities; major events also produced marked facies changes at the PAC 3-PAC 4 boundary and at the PAC 6-PAC 7 boundary (fig. 5).
Interpretation of the Manlius-Coeymans Formation boundary as an unconformity at Thacher Park is based on the absence of PAC 8 and on the sharp contact separating markedly disjunct facies. Farther to the south along the Hudson Valley progressively more PACs were eroded as a result of differential uplift of the eastern side of the basin.

A6: STRUCTURE AND ROCK FABRIC WITHIN THE CENTRAL AND SOUTHERN ADIRONDACKS
James McLelland
Department of Geology
Colgate University
Hamilton, NY

A6: STRUCTURE AND ROCK FABRIC WITHIN THE CENTRAL AND SOUTHERN ADIRONDACKS

STOP 1. Peck Lake Fm.
This exposure along Rt. 29A just north of Peck Lake is the type locality of the sillimanite-garnet-biotite-quartz-feldspar gneisses (kinzigites) of the Peck Lake Fm. In addition, there are exposed excellent minor folds of several generations. Note that the F2 folds rotate an earlier foliation.
The white quartzo-feldspathic layers in the kinzigites consist of quartz, two feldspars, and garnet and are believed to be anatectic. Note that fish-hook terminations on some of these suggest that they have been transposed. It is also clear that these anatectites have been folded by F2 indicating a pre-F2 metamorphic event(s). In a similar fashion some garnets in the rock appear to be flattened while others do not. It is believed that the anatectites formed at the muscovite-quartz reaction and are essentially in situ melts. Further anatexis did not take place due to absence of vapor.

STOP 2. Irving Pond Fm., .5 mile north of Nick Stoner's Inn, Canada Lake .
The outer portion of the Irving Pond Fm. is exposed in low cuts along the east side of Rt. 29A just prior to the crest in the road heading north.
At the southern end of the cut typical, massive quartzites of the Irving Pond are seen. Proceeding north the quartzites become "dirtier" until they are essentially quartzose sillimanitegarnet-biotite-feldspar gneisses (kinzigites).
At the northern end of the cut, and approximately on the Irving Pond/Canada Lake Fm. contact there occurs an excellent set of F2 minor folds. Polished slabs and thin sections demonstrate that these fold an earlier foliation defined by biotite flakes and flattened quartz grains.
The Irving Pond Fm. is the uppermost unit in the stratigraphy of the southern Adirondacks. Its present thickness is close to 1000 meters, and it is exposed across strike for approximately 4000 meters. Throughout this section massive quartzites dominate.

STOP 3. Canada Lake Charnockite
These large roadcuts expose the type section of the Canada Lake charnockite. Lithologically the charnockite consists of 20-30% quartz, 40-50% mesoperthite, 20-30% oligoclase, and 5-10% mafics. The occurrence of orthopyroxene is sporadic. These exposures exhibit the olive-drab coloration that is typical of charnockites. Note the strong foliation in the rock.
Although no proto1ith is known with certainty for these rocks a metavolcanic history is suggested by their homogeneity and lateral continuity. Their bulk chemistry corresponds to dacites.

Canada Lake Store. Good exposures of Royal Mt. member of Green Lake Fill.

STOP 4. Rooster Hill megacrystic gneiss at the north end of Stoner Lake.
This distinctive unit is believed to be, in part, correlative with the Little Moose Mt. Fm. Here the unit consists of a monotonous series of unlayered to poorly layered gneisses characterized by large (1-4") megacrysts of perthite and microcline perthite. For the most part these megacrysts have been flattened in the plane of foliation as well as elongated in an E-W direction with concomitant developed of tails of grain-size reduced tails asymmetric to foliation. However, a few megacrysts are situated at high angles to the foliation. The groundmass consists of quartz, oligoclase, biotite, hornblende, garnet, and occasional orthopyroxene. An igneous rock analogue would be quartz-monzonite or granodiorite depending on concentration of K-feldspar.
The origin of the Rooster Hill is obscure. Its homogeneity over a thickness approaching 2.5 km suggests an igneous parentage. This conclusion gains support from the presence of localities where megacrysts appear to retain a random orientation, and from the occasional presence of what may be drawn out xenoliths of biotitic or amphibolitic gneisses. However, these features may be explained by other models. The contacts of the Rooster Hill are always conformable with enclosing units, and this suggests a metastratified (metavolcanic?) origin. However, the anorthosites of the region also show conformable contacts, and this may, in part, be due to tectonic flattening.
Recently Eckelmann (pers. comm.) has studied zircon population morphologies in the Rooster Hill and similar lithologies. His results strongly suggest an igneous plutonic origin. This would be consistent with the igneous origin assigned the Hermon granite of the northwest Adirondacks - a rock that is markedly similar to the Rooster Hill.

Low roadcut in kinzigites of Tomany Mt. Fm.

Long roadcuts of quartzo-feldspathic gneisses and metasediments
Long roadcuts of quartzo-feldspathic gneisses and metasediments of Lake Durant Fm. intruded by metagabbro and anorthositic metagabbro.

Roadcut of anorthositic metagabbro and metanorite.

Excellent examples of anorthositic gabbros
Roadcut on west side of highway shows excellent examples of anorthositic gabbros intrusive into layered pink and light green quartzo-feldspathic gneisses. The presence of pegmatites and cross-cutting granitic veins is attributed to anatexis of the quartzo-feldspathic gneisses by the anorthositic rocks.

Stop 5. Lake Durant and Sacandaga Fms.
Stop 5. Lake Durant and Sacandaga Fms. intruded by anorthositic gabbros and gabbroic anorthosites. These roadcuts are located on Rt. NY 10 just south of Shaker Place.
The northernmost roadcut consists of a variety of metasedimentary rocks. These lie directly above the Piseco anticline and are believed to be stratigraphically equivalent to the Sacandaga Formation. The outcrop displays at least two phases of folding and their related fabric elements. These are believed to be F2 and F3. A pre-F2 foliation is thought to be present. Both axial plane foliations are well developed here. Several examples of folded F2 closures are present and F2 foliations (parallel to layering) can be seen being folded about upright F3 axial planes.
Farther to the south, and overlooking a bend in the west branch of the Sacandaga River, there occurs a long roadcut consisting principally of pink and light green quartz-perthite gneiss belonging to the Lake Durant Fm. About half-way down this roadcut there occurs a large boudin of actinolitic and diopsidic gneiss. To the north of the boudin the quartzo-feldspathic gneisses are intruded pervasively by anorthositic gabbros, gabbroic anorthosites, and various other related igneous varieties. At the north end of the cut and prior to the metastratified sequences these intrusives can be seen folded by upright fold axes. They are crosscut by quartzo-feldspathic material.
Within this general region the Lake Durant Fm. and other quartzofeldspathic gneisses seem to have undergone substantial anatexis. This is suggested by the "nebular" aspect of the rocks. Good examples of this are seen in the manner in which green and pink portions of the quartzo-feldspathic gneisses mix. Note also the clearly cross-cutting relationships between quartzofeldspathic gneiss and mafic layers at the south end of the roadcut. Here it seems that mobilized Lake Durant is cross-cutting its own internal stratigraphy. Also note that the quantity of pegmatitic material is greater than usual. This increase in anatectic phenomena correlates closely with the appearance of extensive metagabbroic and metanorthositic rocks in this area. It is believed that these provided a substantial portion of the heat that resulted in partial fusion of the quartzo-fe1dspathic country rock.

Red-stained basal quartzo-feldspathic gneisses that have been faulted along NNE fractures.

Stop 6. Core rocks of the Piseco anticline.
Hinge line of Piseco anticline near domical culmination at Piseco Lake. The rocks here are typical basal quartzo-feldspathic gneisses such as occur in the Piseco anticline and in other large anticlinal structures, for example Snowy Mt. dome, Oregon dome.
The pink "granitic" gneisses of the Piseco anticline do not exhibit marked lithologic variation. Locally grain size is variable and in places megacrysts seem to have been grain size reduced and only a few small remnants of cores are seen. The open folds at this locality are minor folds of the F3 event. Their axes trend N70W and plunge 10-15° SE parallel to the Piseco anticline. Co-axial F2 isoclines are also present.
The most striking aspect of the gneisses in the Piseco anticline is their well-developed lineation. This is expressed by rodding and ribbon fabrics. These may consist of alternating ribbons of quartz, quartzo-feldspathic gneiss, and biotite-rich layers. In some instances the rods represent transposed layering on the highly attenuated limbs of early, isoclinal minor folds. Near the northeast end of the roadcut such minor folds are easily seen due to the presence of more massive layers in the rock. Slabbed and polished specimens from this and similar outcrops demonstrates that these early folds are exceedingly abundant in the Piseco anticline. Examination of these folds shows that the dominant foliation in the rock is axial planar to them.
The lineation in these outcrops is shown in Fig. 8a while slabbed sections are shown in Figs. 8b,c. Fig. 8b is cut perpendicular to foliation and both parallel to (left face) and perpendicular to (right face) lineation. As can be seen K-feldspar augen have been elongated in the direction of lineation. Together with elongated quartz aggregates, these grain size reduced minerals form the prominent mineral lineation that characterizes foliation surfaces (Fig. 8a). Note that the K-feldspar augen exhibit shapes closer to equant on the right hand face at perpendicular to lineation. This strongly suggests that the rock fabric is the result of rotational strain in the direction parallel to lineation, i.e., the lineation is an elongation, or stretching type. Fig. 9 shows a less deformed sample slabbed perpendicular to foliation and parallel to lineation. The development of tails on K-feldspar augen are clearly visible. These are the result of grain size reduction during ductile rotational strain. A sinistral (east over west) sense of motion is indicated. At more extreme conditions of strain the K-feldspar augen and quartz aggregates are drawn into ribbons as in the present outcrop. Long dimensions of 40-60 cm are common along with thicknesses of a millimeter, or less. Clearly strain has been extreme and elongations of 30-40 times are not unusual.
Ribbon gneiss origin by rotational strain is also suggested by the parallelism between lineation and F2, F3 fold axes. It is believed that these fold axes were drawn into parallelism with the lineation by ductile, rotational strain directed from east to west. The most satisfactory mechanism for this configuration is the stacking of thrust sheets and thrust nappes during plate collision. Thrusts have been recognized to the east of Lake George (Fig. 4) and others probably exist although the intense, ductile nature of the deformation has resulted in extremely subtle truncations that are difficult to recognize. Sheath folds (Fig. 10) with tube axes parallel to lineation are consistent with this model. Presumably crustal thickening during the Grenville Orogeny was caused by the stacking of these thrusts.

Stop 7. Blue Mt. Lake Fm. exposed in roadcuts on both sides of highway.
The Blue Mt. Lake Fm. is exposed in roadcuts on both sides of the highway. These exposures show typical examples of the extreme ductility of the carbonate-rich units. The south wall of the roadcut is particularly striking, for here relatively brittle layers of garnetiferous amphibolite have been intensely boudinaged and broken. The marbles, on the other hand, have yielded plastically and flowed with ease during the deformation. As a result the marble-amphibolite relationships are similar to those that would be expected between magma and country rock. Numerous rotated, angular blocks of amphibolite are scattered throughout the marble in the fashion of xenolith, in igneous intrusions. At the eastern end of the outcrop tight isoclinal folds of amphibolite and metapelitic gneisses have been broken apart and rotated. The isolated fold noses that rema in "floating" in the marble have been aptly termed "tectonic fish." The early, isoclinal folds rotate on earlier fo1iation.
Near the west end of the outcrop a deformed layer of charnockite is well exposed. In other places the charnockite-marble interlayering occurs on the scale of one to two inches.
Exposed at several places in the roadcut are cross-cutting veins of tourmaline and quartz displaying a symplectic type of intergrowth. Other veins include hornblende and sphene bearing pegmatites.
Commonly included in the Blue Mt. lake Fm., but not exposed here, are quartzites, kinzigites; sillimanite rich, garnetiferous quartz-microcline gneisses; and fine grained garnetiferous leucogneisses identical to those characterizing the Sacandaga Fm. These lithologies may be seen in roadcuts .5 mile to the south.
Almost certainly these marbles are of inorganic origin. No calcium carbonate secreting organisms appear to have existed during the time in which these carbonates were deposited (> 1 b.y. ago). Presumably the graphite represents remains of stromatolite-like binding algae that operated in shallow water, intertidal zones. If so, the other roadcut lithologies formed in this environment as well. This seems reasonable enough for the clearly metasedimentary units such as the quartzites and kinzigites. The shallow water environment is much more interesting when applied to the charnockitic and amphibolite layers. The fine scale layering, and ubiquitous conformity of these, strongly suggests that they do not have an intrusive origin. Perhaps they represent the metamorphosed products of volcanic material in a shelf like environment. Such intercalation is now occurring in many island arc areas where shallow water sediments cover, and in turn are covered by, ash and lava. Alternatively they may represent metasediments. A large lumber of minerals are developed within these outcrops. Both calcite and minor dolomite are present in the carbonate horizons. These are accompanied by green diopside and serpentinized forsterite as well as by tourmaline, graphite, and various sulfides. In calcsilicate horizons phlogopite, diopside (white), and tremolite occur. Wollastonite is locally present. The presence of tremolite and wollastonite is believed to be a function of the relative concentration of CO2 and H2O in the vapor phase Valley et al., 1983).

Extensive roadcuts in lower part of Blue Mt. Lake Fm.
Quartzites, kinzigites, and leucogneisses dominate. Minor marble and calcsilicate rock is present.

Large roadcuts in lower Lake Durant Fm.
Pink, well-layered quartzo-feldspathic gneisses with subordinate amphibolite and calcsilicate rock.

Stop 8. Intermediate Adirondack anorthositic gneiss
On the west side of the road small roadcut exposes an excellent example of Adirondack anorthositic gneiss intermediate in character between the so-called Marcy type (coarse) and the Whiteface type (fine grained). About 50% of the rock consists of fine grained crystals of andesine plagioclase. Some of these crystals appear to have measured from 6-8" prior to grain size reduction. Excellent moonstone sheen can be seen in most crystals. In places ophitic to subophitic texture has been preserved with the mafic phase being represented by orthopyroxene.
In addition to the anorthosite there exists a clearly crosscutting set of late iron-rich orthopyroxene rich dikes containing xenoliths of coarse grained anorthosite. The latter may represent a late mafic differentiate related to cotetic liquids responsible for the ophitic intracrystalline rest magma. This would be consistent with the iron enrichment trend characteristic of Adirondack igneous differentiation.
Near road level there can be found several inclusions of calcsilicate within the anorthositic rocks. These are believed to have been derived from the Cedar River Fm. and are consistent with a non-basement status for the anorthosite.
The upper, weathered surface of the outcrop affords the best vantage point for studying the textures and mineralogy of the anorthositic rocks. In several places there can be seen excellent examples of garnet coronas of the type that are common throughout Adirondack anorthosites. These coronas are characterized by garnet rims developed around iron-titanium oxides and pyroxenes. Recently McLelland and Whitney (1977) have succeeded in describing the development of these coronas according to the following generalized reaction:
Orthopyroxene + Plagioclase + Fe-bearing oxide + quartz = garnet + clinopyroxene.
This reaction is similar to one proposed by de Waard (1965) but includes Fe-oxide and quartz as necessary reactant phases. The products are typomorphic of the garnet-clinopyroxene subfacies of the granulite facies (de Waard 1965). The application of various geothermometers to the phases present suggests that the P,T conditions of metamorphism were approximately 8 Kb and 700 ± 50°C respectively.

Cedar River Fm. Minor marble, amphibolite, and calcsilicate rock.
Predominantly very light colored sillimanite-garnet-quartz-K-feldspar leucogneisses.

Leucogneisses of the Blue Mt. Lake Fm.
To the west of the intersection are roadcuts in leucogneisses of the Blue Mt. Lake Fm. A large NNE normal fault passes through here and fault breccias may be found in the roadcut and the woods beyond.

Entering Little Moose Mt. Fm.
Entering Little Moose Mt. Fm. on northern limb of the Glens Falls syncline. Note that dips of foliation are to the south.

Downdropped block of lower Paleozoic sediments.
Entering town of Wells which is situated on a downdropped block of lower Paleozoic sediments. The minimum displacement along the NNE border faults has been determined to be at least 1000 meters.

Silver Bells ski area to the east.
The slopes of the ski hill are underlain by coarse anorthositic gabbro intrusive into the Blue Mt. Lake Fm.

Lake Durant Fm
On the north side of NY Rt. 30 are quartzo-feldspathic gneisses and calcsilicate rocks of the Lake Durant Fm. An F1 recumbent fold trends subparallel to the outcrop and along its hinge line dips become vertical.

Gabbro and anorthositic gabbro.

Stop 9. Pumpkin Hollow.
Large roadcuts on the east side of Rt. 30 expose excellent examples of the Sacandaga Fm. At the northern end of the outcrop typical two pyroxene-plagioclase granulites can be seen. The central part of the outcrop contains good light colored sillimanite-garnet-microcline-quartz gneisses (leucogneisses). Although the weathered surface of these rocks are often dark due to staining, fresh samples display the typical light color of the Sacandaga Fm. The characteristic excellent layering of the Sacandaga Fm. is clearly developed. Note the strong flattening parallel to layering and the lineation developed on many foliation surfaces. These gneisses are similar to so-called straight gneisses found in proximity to ductile shear zones. The Sacandaga Fm. may represent mylonitic rocks of this type and its layering may, in fact, be tectonic.
Towards the southern end of the outcrop calc-silicates and marbles make their entrance into the section. At one fresh surface a thin layer of diopsidic marble is exposed. NO HAMMERING PLEASE. Many "punky" weathering layers in the outcrop contain calc-silicates and carbonates.
At the far southern end of the roadcut there exists an exposure of the contact between the quartzo-feldspathic gneisses of the Piseco anticline and the overlying Sacandaga Fm. The hills to the south are composed of homogeneous quartzofeldspathic gneisses coring the Piseco anticline (note how ruggedly this massive unit weathers). The Sacandaga Fm. here has a northerly dip off the northern flank of the Piseco anticline and begins its descent into the southern limb of the Glens Falls syncline.
No angular discordance or other indications of unconformity can be discerned at the base of the Sacandaga Fm. However, this does not preclude the prior existence of an angular discordance which may have been swept into pseudoconformity by tectonism.
Along most of the roadcut there can be found excellent examples of faults and associated pegmatite veins. Note that the drag on several of the faults gives conflicting senses of displacement. The cause of this is not known to the author. Also note the drag folds which indicate tectonic transport towards the hinge line of the Piseco anticline.

Core of the Piseco anticline.
All exposures are within the basal quartzo-feldspathic gneisses at the core of the Piseco anticline.

Re-enter the Sacandaga Fm. Dips are now southerly.

Southerly dipping quartzo-feldspathic gneisses of Lake Durant Fm.
In long roadcuts of southerly dipping quartzo-feldspathic gneisses of Lake Durant Fm.

A7: CAMBRO-ORDOVICIAN SHOALING AND TIDAL DEPOSITS MARGINAL TO IAPETUS OCEAN AND MIDDLE TO UPPER DEVONIAN PERITIDAL DEPOSITS OF THE CATSKILL FAN-DELTAIC COMPLEX
Gerald M. Friedman
Department of Geology
Brooklyn College
and
Rensselaer Center of Applied Geology
Affiliated with Brooklyn College of the
City University of New York
P.O. Box 746, 15 Third Street
Troy, New York 12181
This field trip, in which sedimentary facies deposited in Cambrian, Ordovician, and Middle to Upper Devonian shallow-water marine environments will be examined, has been divided into two parts. The first three stops will be devoted to facies of the Cambro-Ordovician period, and the last three will cover the Middle to Upper Devonian facies.

A7: CAMBRO-ORDOVICIAN SHOALING AND TIDAL DEPOSITS MARGINAL TO IAPETUS OCEAN AND MIDDLE TO UPPER DEVONIAN PERITIDAL DEPOSITS OF THE CATSKILL FAN-DELTAIC COMPLEX

STOP 1. Lester Park
PRODUCTS OF INTERTIDAL ENVIRONMENT: DOMED ALGAL MATS (CABBAGE HEADS)
This locality is the site of one of the finest domed algal mats to be seen anywhere preserved in ancient rocks. On the east side of the road in Lester Park a glaciated surface exposes horizontal sections of the cabbage-shaped heads composed of vertically stacked, hemispherical stromatolites (Figure 5). These structures, known as Cryptozoons, have been classically described by James Hall (1847, 1883), Cushing and Ruedemann (1914), and Goldring (1938); an even earlier study drew attention to the presence of ooids as the first reported ooid occurrence in North America (Steele, 1825). Interest in these rocks has been revived as they are useful environmental indicators (Logan, 1961, Fisher, 1965; Halley, 1971). The algal heads are composed of discrete club-shaped or columnar structures built of hemispheroidal stromatolites expanding upward from a base, although continued expansion may result in the fusion of neighboring colonies into a Collenia-type structure (Logan, Rezak, Ginsburg, 1964). The stromatolites are part of the Hoyt Limestone of Late Cambrian (Trempealeauan) age. An intertidal origin has been inferred for these stromatolites (Fig. 6, 7 and 8).
The evidence for deposition under tidal conditions for the Hoyt Limestone at Lester Park includes: (1) mud cracks, (2) flat-pebble conglomerate, (3) small channels, (4) cross-beds, (5) birdseye structures, (6) syngenetic dolomite, and (7) stromatolites (for characteristics on recognition of tidal limestones, see Friedman, 1969).
At Lester Park the heads which are circular in horizontal section range in diameter from one inch to three feet; many are compound heads. The size of the larger heads suggests that they formed in highly turbulent waters.
The line of depositional strike along which the domed stromatolites occur was probably where the waves were breaking as they came across the deeper ocean from the east and impinged on the shelf.
Several petrographic observations in these rocks permit an analogy with modern algal mats in hypersaline pools of the Red Sea Coast (Friedman and others, 1973). Mat-forming algae precipitate radial ooids, oncolites, and grapestones which occur in these rocks; interlaminated calcite and dolomite, which in part compose the stromatolites of the Hoyt Limestone, correspond to alternating aragonite and high-magnesium calcite laminites which modern blue-green algae precipitate. In modern algal mats the highmagnesium has been concentrated to form a magnesium-organic complex. Between the magnesium concentration of the high-magnesium calcite and that of the organic matter, sufficient magnesium exists in modern algal laminites to form dolomite. Hence the observation in ancient algal mats, such as observed in the Hoyt Limestone, that calcite and dolomite are interlaminated, with calcite, probably forming at the expense of aragonite and dolomite forming from high-magnesium calcite.

STOP 2. Fort Hunter Quarry
Stromatolites in the Fort Hunter Quarry consist almost entirely of dolomite in the form of irregularly bedded, finely-laminated, undulating structures (Figure 9). The rocks in this quarry are part of the Tribes Hill Formation of earliest Ordovician age (Fisher, 1954). The lithofacies of the Tribes Hill formation have been studied in detail by Braun and Friedman (1969) within the stratigraphic framework established by Fisher (1954). Figure 10 is a columnar section showing the relationship of ten lithofacies to four members of the Tribes Hill Formation. At Fort Hunter we will study the lowermost two lithofacies of the Fort Johnson Member (see column at right (east) end of section, in Fig. 10).
Two lithofacies are observed: (1) lithofacies 1, mottled f~ldspathlc dolomite (Figure 10), and (2) lithofacies 2,. laminated feldspathic dolomite. Lithofacies 1 is at the bottom of the quarry, and lithofacies 2 is approximately halfway up.
Lithofacies 1
This facies occurs as thin dolostone beds, 2 cm to 25 cm but locally more than 50 cm thick, with a few thin interbeds of black argillaceous dolostone which are up to 5 cm thick. In the field, the dolomite shows gray-black mottling and in places birdseye structures. In one sample, the infilling of the birdseyes shows a black bituminous rim which may be anthraxolite. In the field, trace fossils are abundant, but fossils were not noted. Authigenic alkali feldspar (microcline) is ubiquitous throughout this lithofacies; its identity as alkali feldspar was determined by Xray analysis and staining of thin sections with sodium cobaltinitrite. The insoluble residue makes up 22 to 54% by weight of the sediment in samples studied with most of the residue composed of authigenic feldspar. An iron-poor yellow sphalerite may be occasionally found in the rocks of this lithofacies.
Lithofacies 2
This lithofacies is mineralogically identical to the previous facies but differs from it texturally and structurally in being, irregularly bedded and in containing abundant undulating stromatolitic structures ("pseudoripples"), as well as disturbed and discontinuous laminae. In places there are a few thin interbeds of black argillaceous dolostone. The thickness of the laminites of this facies ranges from 1/2 mm to 2 or 3 mm; on freshly broken surfaces the color of the thinner laminae is black and that of the thicker ones is gray. The insoluble residue, for the most part composed of authigenic feldspar, constitutes between 35% and 67% by weight in samples studied.
These two lithofacies which form the basal unit of the Ordovician, were formed on a broad shallow shelf. Stromatolites, birdseye structures, scarcity of fossils, bituminous material, syngenetic dolomite, authigenic feldspar, and mottling suggest that these rocks were deposited in a tidal environment (Friedman, 1969). Based on analogy with the carbonate sediments in the modern Bahamas, Braun and Friedman (1969) concluded that these two lithofacies formed under supratidal conditions. However, in the Persian Gulf flat algal mats prefer the uppermost intertidal environment and along the Red Sea coast they flourish where entirely immersed in seawater, provided hypersaline conditions keep away burrowers and grazers (Friedman and others 1973). Hence on this field trip we may conclude that the stromatolites indicate tidal conditions without distinguishing between intertidal and supratidal. For more details on these lithofacies refer to Braun and Friedman (1969).

Cross original Erie Canal, built in 1822.
Cross original Erie Canal, built in 1822. Amos Eaton surveyed this route at the request of Stephen Van Rensselaer; after this survey Amos Eaton and Van Rensselaer decided to found a school for surveying, geological and agricultural training which became Rensselaer Polytechnic Institute.

STOP 3. North Tribes Hill Quarry
Route of Walk
Take the trail toward old abandoned crusher, but instead of heading toward the quarry move uphill to the first rock exposures. The rocks to be examined are near the edge of steep cliff.o
Description and Discussion
In the rocks at this exposure the field relationships show typical channels truncated at their bases. Lodged within the channels are limestone blocks of variable shape ranging in diameter from about one to three feet. These blocks resemble similar blocks in tidal channels of the Bahamas which are derived by undercutting of the banks of the tidal channels. The blocks at this exposure are rounded, suggesting that they have undergone some transport.
The rocks composing the channel (the channel fill) and the blocks of rock within the channels have been described as lithofacies 8 (Figure 11) (channel fill) and lithofacies 7 (Figure 12) (blocks) of the Wolf Hollow Member of the Tribes Hill Formation (lowermost Ordovician) (see columnar section of Fig. 10); column at right end of the section) (Braun and Friedman, 1969). The channel fill (lithofacies 8) consists of intrasparite and biointrasparite with sporadic ooids, a high-energy facies, whereas the blocks (lithofacies 7) consist of mottled dolomitic micrite and biomicrite, a low-energy facies of the undercut bank. The micrite blocks which foundered in the channels must have been indurated penecontemporaneously (Fig. 13).

STOP 4. Marsh Facies
STOP 4. MARSH FACIES
No examples of the marsh facies have been found in situ. However, giant seed ferns of the Gilboa Forest (Goldring, 1924, 1927), which grew in a marsh environment, were discovered in the now-inactive Riverside Quarry near here. More than 200 stumps were taken from this single quarry; some of these have been placed at this site, others are now preserved in museums. The "trees" of Gilboa Forest are among the world's oldest; they grew in a marsh environment of the Catskill Deltaic complex. The bulbous bases of these fossils were found in place in dark-colored shale; the upright trunks were encased in olive-gray, cross-bedded sandstone of probable tidal origin. The age of the "trees" is latest Middle Devonian.

STOP 5. Intertidal Facies: Tidal Flats and Tidal Channels
The rocks at this exposure are medium-gray, fine-grained graywackes; tabular cross-beds are ubiquitous, parting lineations are common. The most interesting single feature at this exposure are the tidal channels. These channels are small, about 2 to 10 feet in cross-section; they truncate the underlying strata. The channel fill consists mostly of a lag concentration of transported spiriferid brachiopod shells (Figure 14). Usually the shell material is abundant enough to rate for the channel the name "coquinite." Holes in the coquinites are brachiopod molds. Interestingly, brachiopod shells are confined only to the coquinite lenses; they are not found in the surrounding rock. Hence the brachiopods were treated by the channels as pebbles that were washed in from the open marine environment. In analogous modern tidal channels, typical open sea species are washed into the channels by flood tides (Van Straaten, 1956).
An alternate interpretation for the coquinite lenses is that they may be storm deposits. The lenses are lag concentrates of brachiopod shells; in the contiguous sandstones pelecypods, chiefly Unio, occur. If these lenticular coquinite lenses were tidal channels,then according to this alternate interpretation, lateral cutting should have concentrated the molluscs. Yet these lenses are devoid of molluscs, hence storms rather than tidal action should have caused the coquinite lenses.
Load-flow structures, formerly known as ball-and-pillow structures, load casts or storm rollers are locally present. They represent compactional differential loading. These structures may be related to slumping and are common on the front of modern deltas.
Note that the next exposure south (uphill) is composed of red fluvial rocks.
This exposure has been described by Johnson and Friedman as part of their section 43 (1969, p. 471-475, especially Figs. 22 and 23). These rocks are the clastic correlatives of the Tully Limestone (early Late Devonian or latest Middle Devonian).

STOP 6. Deposits Of Lagoons And Bars Or Tidal Deltas
At this exposure lenticular sandstone bodies interfinger with dark-gray siltstones and shales. The sandstones have a vertically shingled, or en echelon, configuration relative to one another. Even the thickest sandstone, approximately 6 feet thick, thins and pinches out laterally (see Fig. 25, p. 478 in Johnson and Friedman, 1969). The sandstones contain marine fossils and wood fragments. In places they are crossbedded; ripple marks are locally present. In the siltstones and shales wood fragments are abundant. The presence of marine fossils, the absence of channels, and the lenticular geometric configuration of the sandstones within interfingering siltstones or shales suggests that the sandstones may be bars or tidal deltas. If so, the siltstones or shales are of lagoonal origin.
The rocks at this exposure belong to the Hamilton Group (Middle Devonian) and are about 600 feet below the stratigraphic level of the Tully clastic correlatives.

A8: ROCKS AND PROBLEMS OF THE SOUTHEASTERN ADIRONDACKS
PHILIP R. WHITNEY
Geological Survey, New York State Museum*
Purpose of the Trip
This trip is a roadcut tour of the easternmost fault block of Proterozoic rocks in the Southeastern Adirondacks, and has two major purposes. For beginners in Adirondack geology, the trip will provide an introduction to the major rock types of the area, as well as to many of the characteristic structural features. For the advanced student or professional, the emphasis will be on the numerous unsolved or partially solved problems presented by these extremely complex rocks.
Introduction
This article is not a report on a finished project, because the writer has not done detailed mapping in the area. The discussion therefore consists largely of preliminary descriptive material, based on a few reconnaissance traverses by the writer and colleagues, plus more detailed examination of the rocks at the scheduled stops, and some very preliminary petrographic work. Previous work in the area includes mapping by Hills (1965) in the southern part of the Pinnacle Range, and by Berry (1961) in the portions of the Whiteball and Putnam quadrangles W and N of the trip area.
Location
The rocks seen on this trip are exposed in roadcuts along Routes 4 and 22 in the Fort Ann and Whitehall 7 1/2 minute quadrangles. They are part of a tilted fault block of Precambrian rocks at the southeastern edge of the Adirondack Highlands, which has been called the Pinnacle Range by Hills (1965). The eastern side of this block is close to the contact with overlying Paleozoic rocks; the unconformity itself is exposed at stop 3.
*Contribution number 462 of the New York State Science Service

A8: ROCKS AND PROBLEMS OF THE SOUTHEASTERN ADIRONDACKS

Outcrops of Cambro-Ordovician Beekmantown carbonates.

Fault block of Precambrian rocks
As you leave the village, notice the range of hills straight ahead. The eastern slope is a dip slope on a fault block of Precambrian rocks (known as the Pinnacle Range) bounded on the west by the Welch Hollow Fault (Hills, 1965). The Paleozoic rocks previously noted are on the downthrown (W) side. This is the easternmost of several such fault blocks, all showing a gentle, regional eastward dip of 10-15° on the Precambrian rocks and overlying paleozoics. The eastern slope of this block is a dip surface close to or at the unconformity, which will be seen in outcrop at stop 3. Is the tilt of this surface a result of a rotation of the fault blocks, or a reflection of the Tertiary-Recent doming of the Adirondacks (Isachsen 1975)?

STOP 1. A plaque on the face of the outcrop
Turn into parking area on R (SE) side of road and cautiously cross road to outcrops on opposite side. A plaque on the face of the outcrop commemorates the Battle of Fort Ann (July 8, 1777). The rocks here are intensely foliated and fractured representatives of the anorthosite suite. Although the characteristic andesine megacrysts found in anorthosites elsewhere in the Adirondacks are absent here, they can be found sporadically in other outcrops along the west side of the Pinnacle Range. Minerals in the anorthosite at this stop consists of recrystallized and sericitized plagioclase, hornblende, clinopyroxene and garnet. Large garnets (please do not sample) are surrounded by leucocratic haloes which locally obliterate the foliation, which suggests that the garnet grew at the expanse of mafic minerals which define the foliation, and that it postdates at least the first deformation.
At the eastern end of the outcrop is a large mass of gabbroic rocks (plagioclase-clinopyroxene- garnet-ilmenite) which displays little or no foliation, and around which the foliation in the anorthositic gneiss is deflected. Also present in the outcrop are a breccia zone and numerous closely spaced fractures with a general northeasterly trend; a major high angle fault may exist roughly parallel to the road.

Coarse marble with amphibolite and gneiss
Outcrops in woods to L of road are coarse marble with numerous detached and rotated blocks of amphibolite and gneiss around which the foliation of the marble is wrapped.

STOP 2. Foliated gneiss with banding and folds
Stop #2. Roadcut on R (SE) side of road. Strongly foliated quartz- 2 feldspar-pyroxene-hornblende-garnet gneisses, ±. biotite. Leucocratic bands contain numerous pyroxene megacrysts, both clino and ortho, the latter showing characteristic rusty weathering color. These rocks are close to the charnockitic end of the migmatitic gray gneiss spectrum. Note the presence of at least two types of amphibolite. One is relatively coarse grained, boudinaged and injected with leucocratic veinlets. The foliation within the boudins is locally truncated by that in the enclosing gneisses. The other amphibolite is dark, fine-grained, biotite-rich, and lacks the leucocratic veining and prominent foliation of the coarser amphibolite. The fine-grained, massive amphibolite forms a megaboudin or recumbent fold (which is it?) near the center of the cut. Do these amphibolites represent one, two, or more generations of mafic intrusives?
Numerous complex minor folds are present within the gneisses; also observe the warping of the foliation by larger, open folds. Measure and record lineations and attempt to relate them to the fold axes of both types. Is more than one lineation present in these rocks?
Thin, folded dark bands near the N end of the cut are a peculiar, fine grained carbonate-rich rock with poorly oriented biotite.

STOP 3. Proterozic / Paleozoic unconformity
The outcrop on the R side of Rte. 4 just beyond the intersection exposes the unconformity between Proterozoic and Paleozoic rocks (missing: roughly 500 million years of the geologic record, and 20-25 km of Proterozoic rock). The Paleozoic rocks here are coarse arkosic sandstones and quartz-pebble conglomerates of the Cambrian Potsdam Formation, locally with carbonate cement. Measure the strike and dip of the unconformity surface, and compare this with the 10-15° easterly slope of the fault block as observed driving N out of Fort Ann.
Observe the lack of evidence for deep weathering of the Precambrian rocks beneath the contact, and the absence of a paleosol layer. This suggests deep erosion and scouring (by waves? ice?) shortly before deposition of the Potsdam.
Walk a few meters along the S face of the outcrop, towards the canal. Note the complex fracturing of the gneisses, and the filling of the fractures with dark, fine-grained dolomitic rock. The significance of this feature is unclear, and it will be discussed in more detail on the trip. Note the deeply weathered zone where these rocks are exposed at the surface.
After examining the unconformity, cautiously cross the road to the cut in complexly deformed gray gneisses on the opposite side. Measure several lineations here and compare with what you saw at stop #2. Note not only differences in orientation, but also in the nature of the lineation.

Potsdam Sandstone
Outcrops at edge of woods on R are fine-grained white arkosic Potsdam sandstones.

Granitic gneisses close to a NS brittle fault.
Outcrops on L are extensively fractured granitic gneisses close to a NS brittle fault.

STOP 4. Kinzigite and amphibolite
The rocks immediately to the R are strongly foliated biotite-quartz-2 feldspar-garnet gneisses. This version of the gray gneiss is commonly referred to as "kinzigite". Present in this outcrop are thin quartzo-feldspathic pegmatites in various stages of tectonic disintegration and reorientation. The large K-feldspars survive the tearing-apart process better than quartz, and remain visible as large porphyroclasts, either in strings or as isolated individuals. Be alert for evidence of tectonic rotation of these feldspars, which can be a useful indicator of the sense of shear.
Also observe the variable shape and appearance of the garnets: some are rounded and others elliptical: some are nearly inclusion-free while others are "spongy". Careful study of this variation might, if combined with probe analysis of garnet compositions, yield information on the interrelation of metamorphism and deformation of these rocks.
From here, walk northward along the road past a gap in the outcrop, then enter the S end of a long cut. The first rocks are strongly foliated and lineated gray gneisses with lenses and pods of calcsilicates. Roughly 30 m. northward and uphill, these overlie amphibolitic rocks, which comprise most of the remainder of the cut. The bulk of these rocks are strongly foliated garnet amphibolites and mafic gneisses. Numerous lenses and pods of calcsilicates, garnet hornblendite, and ultramafic rocks are present. (Students: the coarse grained ultramafic pods are a fine opportunity to test your mineral recognition skills). About 90 m. northward along the cut a large pod of calcsilicate granulite (grossular-diopside-quartz) is visible in the mafic gneisses on the opposite side of the road. Near the N end of the cut, still on the R (E) side, two large pods or megaboudins of massive, relatively fine grained, garnet-rich metagabbro are surrounded by strongly foliated amphibolites. The transition between foliated and unfoliated rock is very abrupt. Patches of tourmaline- bearing pegmatite are present at the broken(?) end of one of the megaboudins.

STOP 5. Gneisses and Gabbros
Cross the road and walk N along the W side. At the S end are more gray gneisses, here with a distinct reddish tinge caused by an abundance of garnet. The gray gneisses here are nearly devoid of K feldspar. They become more strongly foliated toward the contact with overlying pink granitic gneisses. The contact itself is extremely sharp (but note the late spherical, undeformed garnets, some of which are situated directly on the contact). The pink granitic gneisses, which contain biotite, chlorite and garnet, are strongly foliated, approaching mylonitic texture in places, and display prominent quartz ribbon lineation. The less deformed parts of these gneisses contain K-feldspar megacrysts (phenocrysts? porphyroblasts?) in various stages of deformation and recrystallization.
Continuing N, pass a large gabbro pod, broken at the base and injected with granitic material, in part pegmatitic. Look S across the road; the similarly shaped body of gabbroic rock in the pink gneisses is probably the same pod. Then re-enter gray gneisses, here with somewhat more K feldspar, which is concentrated in the leucosomes. Notice the prominent discontinuity in the foliation which is visible for some distance along the cut. Even though little textural evidence (e.g. grain size reduction) for shear displacement exists along the discontinuity, other explanations for this feature are even more difficult to defend. Toward the N end of the cut is another body of gabbroic rock, which also appears to continue on the opposite side of the road. These mafic rocks, which intrude both the gray and pink gneisses, are generally fine grained and massive with a distinct relict igneous texture. Much garnet is present in the form of indistinct coronas. These rocks are the equivalent of the coronitic olivine metagabbros, a more typical example of which will be seen at stop #8. These gabbroic bodies (several are present here) are lensoid to sigmoidal in cross section but apparently elongated in a roughly N-S direction. Their crudely sigmoidal shape yields opposite estimates of shear sense depending on whether they are pre- or syn-tectonic in origin.
Cross the road to the E side, and note the prominent minor folds in the migmatitic gray gneisses near the N end of the cut. Also note the open, upright folds, which warp the foliation of these rocks, then compare the orientation of these with the recumbent, isoclinal minor folds and with the lineation. Then walk S along the E side and return to the starting point. The petrology of the rocks at this outcrop has been studied in detail by William Glassley and students at Middlebury College. Dr. Glassley (pers. comm. 1985) reports the following:
"Garnet-clinopyroxene and garnet-biotite temperatures were computed from microprobe data. Average temperatures from eight samples ranged from 770 C to 850 C, with a strong mode at 810 C. Pressures, calculated from the assemblages garnet-plagioclase-clinopyroxene-quartz and garnet-plagioclase-orthopyroxene-quartz using the method of Newton and Haselton, averaged 7.5 kb + .5 kb.
"Two unusual assemblages can be found along the contact between the two gneiss units. Within 50 cm of the contact occur 1-3 cm long augen which contain the assemblages clinopyroxene-garnet-rutile and biotite-sillimanite-hercynite-kspar-garnet. The former assemblage is a typical eclogite assemblage. Garnets from these eclogitic lenses are similar to those reported from basal gneiss eclogites in Western Norway. The clinopyroxenes, however, are poor in jadeite component, with only 5% of this component present. The sillimanite- spinel-bearing assemblage is clearly consumed and biotite and sillimanite are being generated. The significance of this assemblage for P-T conditions remains obscure, in that we do not yet have compositional data for all of the minerals in the assemblages nor do we have water fugacity values that would allow calculation of the equilibrium conditions."

STOP 6. (Optional) Paragneiss
The rock here is a pale gray biotite-quartz-2 feldspar-garnet-sillimanite-graphite paragneiss with thin layers and lenses of calcsilicates. Compared to the previously examined "kinzigites", this rock is finer grained, more aluminous, and has distinctive lavender garnets. The abundant white layers look like leucosomes in a migmatite, but they contain significant amounts of sillimanite and are thus probably more aluminous than minimum-melt granite. Note the flattening of the quartz in these layers. Look carefully for lineations defined by sillimanite and quartz.
The protolith of these rocks must have had a significant argillaceous component, as indicated by the presence of both garnet and sillimanite. The lavendar-colored garnets are typical of many Adirondack metapelites, a more extreme example of which will be seen at Stop #9.

STOP 7. North end of roadcut.
Pull off road on R and cautiously cross to outcrops at N end of cut on west side; walk S along outcrop. Probably the best way to appreciate these rocks is to move rather rapidly to the S end, scanning the rocks on both sides as you go for major lithologic changes, and then return northward looking at the rocks in detail.
The sequence of rock types going S on the W side is as follows:
A Interlayered (or interleaved?) marbles and paragneisses
B Garnetiferous quartzofeldspathic gneisses intruded by unmetamorphosed mafic dikes
- Gap -
C Charnockitic gneiss
D Thin marble with numerous exotic blocks
E Mafic gneiss
F Calcsilicates and marble
G Interlayered (interleaved?) Paragneiss, charnockite, marble and calcsilicate with amphibolite boudins. An unmetamorphosed mafic dike forms the face of much of this section of the cut.
Details (walking N)
G. Note the wide variety of rock types, including charnockitic gneisses, amphibolites, marble (carefully examine the marble/amphibolite contact), lineated sillimanite bearing metapelites, and calcsilicates. Note the local slickensides along foliation surfaces as well as on vertical fractures. Has there been late movement parallel to the foliation?
F. This thin calcareous unit consists of marble near the base and a complex calcsilicate zone adjacent to the contact with the overlying mafic gneiss. Major minerals in the calcsilicate zone are grossular, diopside, quartz, calcite and K feldspar, with lesser amounts of plagioclase and chlorite as well as several minor phases yet to be identified. Some evidence indicates that wollastonite was initially present but none has yet been positively identified. The calcsilicates probably originated by contact metamorphism at the time of intrusion of the igneous precursor of the overlying mafic gneiss. This contact is irregular and appears to have been folded. The thickness of the calcsilicate layer varies widely, both in this outcrop and on the opposite side of the road.
E. This mafic gneiss contains plagioclase, clinopyroxene, hornblende, biotite, garnet and minor quartz and K feldspar. The composition is probably similar to a monzodiorite. Similar rocks elsewhere in the Adirondacks have been called "jotunite" and are associated with the anorthosite suite of rocks. The rock is well foliated throughout, but becomes more so towards the sharp upper contact. On the opposite (E) side of the road, a detached sliver of the mafic gneiss is found in the overlying marble, and contains carbonate-filled fractures.
D. The next unit upward is a thin (generally < 1 m) band of marble with numerous rotated fragments of other rocks. No calcsilicates are developed near the sharp contact with the mafic gneiss beneath, and the foliation both in the mafic gneiss and in the overlying charnockitic gneiss is strongly developed and parallel to the marble band. In the outcrop on the opposite side of the road, foliation in the charnockite is locally truncated by the marble. This marble is a good example of a possible detachment zone, with relative movement of uncertain direction and magnitude, between the mafic gneiss and the charnockite. The absence of a contact metamorphic zone of calcsilicates at the upper contact of the mafic gneiss may result from its having sheared off during displacement. Alternatively, this marble may be a tectonically emplaced younger rock (see discussion under unit "A", below). Considerable displacement may have taken place along most or all of the marble layers in this outcrop.
C. Above the marble is a thick unit of charnockitic gneiss. This rock, close to granite in composition, consists of quartz, microcline, plagioclase, hornblende, garnet, clinopyroxene and orthopyroxene. The orthopyrcxene is extensively chloritized, which is characteristic of many Adirondack charnockites. The typical green color is well developed toward the center of the unit. Near the northern end of the outcrop both green and white varieties are present, with diffuse color boundaries which crosscut foliation.
Immediately beyond the charnockite unit is a gap in the outcrop, possibly indicating the presence of a fault or thick marble layer.
B. Following the gap is a short section of well foliated, garnetiferous quartzofeldspathic gneisses similar to the charnockite but with green color less well developed. Note the unmetamorphosed mafic dike just back from the face of the outcrop, and roughly parallel to it. A few meters farther N is a complex vertical fault with a zone of carbonate-cemented breccia.
A. The last section of the outcrop, roughly 100 m long, consists of interlayered (interleaved?) paragneiss and marble, with minor amphibolite and thin calcsilicate bands in the paragneiss. Contact surfaces are frequently slickensided and/or coated with graphite. At least two types of marble are present; one is dark, relatively fine grained, brown-weathering dolomite marble, which has a slightly fetid odor when struck with a hammer; the other is coarser grained, has a somewhat lighter color and considerable calcite as well as dolomite. Both marbles contain abundant rounded to angular silicate rock and mineral fragments, including quartz, feldspar and serpentine, and larger rotated blocks of various rock types including amphibolites, serpentinite, paragneiss and calcsilicate granulite. Quartz, dolomite and serpentine coexist in these rocks with no evidence of mutual reaction, indicating that the rock as presently constituted has never undergone high temperature metamorphism. Temperatures must have been sufficiently low to prevent reaction of quartz with either dolomite or serpentine. It is probable that these marble zones, as well as those of units G, F and D, are tectonic breccias formed along thrust faults or low-angle normal faults under conditions that permitted the carbonates to recrystallize and deform in ductile fashion, while silicates behaved in a more brittle manner. The interleaved paragneisses, by contrast, are similar to the gray gneisses seen in previous stops, have a high-T metamorphic assemblage and show little evidence of retrogression.
The age of the tectonic interleaving of the gneisses and marbles may be either late Proterozoic or Taconic. The marbles themselves may be Proterozoic with retrograde serpentine after forsterite and entrained fragments of quartz and feldspar, or they may be Paleozoic carbonates with entrained fragments of ultramafic rocks. This question is now under study and will be discussed on the outcrop.

STOP 8. (Optional) Typical Adirondack olivine metagabbros
Stop #8 (Optional). Park as far off the road to the R as possible. Cross with great care to outcrops on the L, and examine them briefly. These are typical Adirondack olivine metagabbros, with well preserved igneous textures as well as coronitic reaction rims around olivine and ilmenite (see introductory section). The interiors of the olivine coronas here have been retrograded to chlorite and carbonate; otherwise the rocks are quite fresh.

Dip-slope on foliation
Flat outcrops on slopes to the L are a dipslope on foliation in highly strained gneisses. A short distance N, on West Mtn., a mylonite zone close to 300 m thick is exposed. The hills across the valley to the R, and on Skene Mtn. straight ahead, are Cambro- Ordovician carbonates of the Whitehall Formation, resting on Potsdam sandstone.

STOP 9. Typical metapelites
Pull off road to R close to smaller outcrop, and cross to larger cut on L. The rocks here are typical metapelites, consisting of quartz, K feldspar, sillimanite, lavender garnet and varying amounts of biotite and graphite.

Entering series of cuts in highly fractured metasedimentary rocks.

STOP 10. Abandoned Quartzite Quarry
Entrance to abandoned quarry and Washington County Highway Dept. Garage. This is posted private property; if following this road log on your own, ask permission at large brick farmhouse 0.2 miles further along road on R. Be extremely careful climbing and hammering here - there is much loose rock and the quartzite is very splintery when hammered.
This thick unit of quartzite is interlayered with lesser amounts of a greenish rock which forms bands and streaks from a fraction of a millimeter up to several tens of centimeters thick, with knifesharp contacts against the quartzite.
The quartzite, which is visibly foliated in hand specimen, comprises over 95% of strongly flattened quartz; small, flattened and elongated grains of K feldspar and sericitized plagioclase, lensoid garnets, green biotite and chlorite. The interlayered green rock ranges from plagioclase-quartz-garnet-biotite-hypersthene gneiss to a retrograded epidote-chlorite-quartz-plagioclase rock with some muscovite and at least two minerals yet to be identified. Some well crystallized chlorite is present as flakes parallel to the foliation, but chlorite also occurs locally as an alteration product of garnet. Distribution of the retrograde assemblage within the outcrop has not been determined. If it is related to fracture patterns, it may be low temperature alteration along the E-W brittle fault which parallels the road. If not, it may be evidence for localized retrogression associated with renewed, layer- parallel shearing during the latest Proterozoic or during the Taconic event. Supporting the latter hypothesis are slickensides on foliation surfaces at an acute angle to the lineation.
All rocks at this site show extreme foliation and a well developed lineation, here close to E-W, with a 0-20° E plunge. Numerous minor folds are present. These are of two distinct types, both of which are recumbent with axes parallel to the lineation. One type consists of intrafolial, highly asymmetric, isoclinal folds defined by thin micaceous layers in the quartzite. Among folds of this type is an apparent sheath fold strongly flattened in the plane of foliation. The other type is not quite isoclinal, more symmetric, and visibly folds the foliation in the quartzite. The minor folds and petrofabrics at this outcrop have been described by Granath and Barstow (1980), who attribute the deformation primarily to a severe flattening strain.

Fault bounded block
Crossing South Bay on Lake Champlain. The rocks underlying the valley to the North are Paleozoic strata downdropped along a major normal fault which here forms the western side of the Pinnacle Range.
Toward the south, this fault intersects the Welch Hollow fault at an oblique angle. The fault follows the shore of South Bay south of the bridge, then strikes inland and follows the line of cliffs visible to the north. Estimated vertical displacement on this fault based on offset of Paleozoic cover rocks is in the vicinity of 300 m. West of the bay, outcrops of gently E-dipping, highly deformed Precambrian rocks resume.

A9: CAMBRIAN AND ORDOVICIAN PLATFORM SEDIMENTATION - SOUTHERN LAKE CHAMPLAIN VALLEY
Bruce Selleck
Colgate University
Brewster Baldwin
Middlebury College
The Cambrian-Medial Ordovician strata of the southern Lake Champlain Valley record the evolution and demise of passive margin sedimentation on the North American coast of the proto-Atlantic Ocean. The goals of our trip are to examine exposures of key units in this stratigraphy, interpret the depositional environments represented and consider the possible tectonic controls over the history of platform sedimentation during the early Paleozoic in eastern North America.
Our trip will focus on two sections of the stratigraphy: (1) the Late Cambrian Ticonderoga Dolostone and basal Whitehall Formation and (2) the Medial Ordovician Chazy, Black River and Trenton Groups. The general area of interest (Fig. 1) lies within the Ticonderoga and Port Henry, N.Y. 151 Quadrangles.

STOP 1A. Ticonderoga Dolostone
Relatively new roadcuts on Shore Airport Road provide excellent exposures of portions of the Ticonderoga Dolostone and Whitehall Formation. The generalized stratigraphy of this series of outcrops is presented on the following pages. Stop 1A is wholly within the Ticonderoga Dolostone; lB is uppermost Ticonderoga Dolostone or basal Whitehall (Finch Dolostone of Fisher, 1984) Formation; Stop lC is clearly Whitehall Formation, Finch Dolostone Member. We will walk upsection from the base of Stop 1A to Stop 1B, reboard the bus to Stop 1C. Please watch for cars!
A series of normal faults juxtapose blocks containing various sections of the Cambro-Ordovician stratigraphy in the Ticonderoga area. To our southwest, Proterozoic marbles and gneiss hold up Prospect Mountain. The village of Ticonderoga largely sits upon Potsdam Sandstone (Keeseville Member). To our south and east, the younger formations of the Beekmantown Group are exposed in the vicinity of Fort Ticonderoga. At this stop approximately 20 meters of Ticonderoga Dolostone is exposed. The basal 2/3 of the outcrop consists of 0.2 - 1.0 meter units of bioturbated sandy dolostone interbedded with 0.1-1.0 meter units of cross-stratified slightly dolomitic medium to fine sandstones. Rare prism cracks in the fine silty dolostones document sporadic subaerial exposure. "Herringbone" cross-strata, reactivation surfaces and shear-deformed cross-strata are well-exposed on weathered surfaces of the sandstones. Poorly preserved specimens of the gastropod Ophileta sp. are found on the bedding surface of a dolomitic sandstone approx. 8 meters from the base of the section. R. Linsley (personal communication) has suggested that Ophileta, was a relatively sedentary grazer or deposit feeder. The upper 1/3 of the section contains relatively more abundant prism cracks, sha1y interbeds and intraclast breccia horizons, perhaps indicating more regular subaerial exposure.
The rhythmically interbedded bioturbated dolostones and cross-stratified dolomitic sandstones are interpreted as high and low tidal flat/shallow subtidal facies, respectively. Carbonate mud and terrigenous sands deposited on a relatively low energy upper intertidal flat provided a suitable habitat for burrowing infaunal organisms. The lower tidal flat and shallow subtidal environment was characterized by more vigorous current action which limited faunal activity and produced cross-strata and associated structures. The repetitive interbedding of these facies suggests repetitive progradation of burrowed sandy muds over current-bedded sands. The upsection decrease in current-produced structures and increasing evidence of exposure indicates an overall shallowing up trend in the Ticonderoga Dolostone at this locality.

STOP 1B. North side of Shore Airport Road, 150 m from STOP 1A
This outcrop exposes about 7 m of silty, cherty dolostones assignable to either the uppermost Ticonderoga Dolostone or the basal Finch Member of the Whitehall Formation. The pervasive dolomitization plus outcrop weathering have obscured the primary structures and fabrics. The lower approx. 1 meter consists of laminated silty dolostones with ripple cross-lamination and thin intraclastic horizons. The succeeding 1.5 meters consists of thick-bedded to massive coarsely crystalline dolostone containing calcite-filled voids of various sizes. The succeeding 2 meters consists of bioturbated, dark medium crystalline dolostone with vaguely developed digitate algal (?) structures. Laminated, finely crystalline dolostones follow, capped by dolostones with algal mounds. In the upper 1 1/2 m of the outcrop, cherty, laminated dolostones apparently drape an irregular algal mound (thrombolites) surface. Note laminated silty dolostone between algal mounds.
The lack of diagnostic fossils and primary structures ln these lithologies make environmental assignment difficult. If the digitate algal structures and cryptalgal laminites are indeed present, a shallow subtidal to low intertidal environment may be inferred. Bioturbated dolostones could be of intertidal or more offshore origin. Any suggestions?? (We will reboard bus at this point and continue east on Shore Airport Road 400 meters to Stop 1 C.)

STOP 1C. Outcrop on north side of road, 400 m from STOP 1B
Approximately 3 1/2 meters of the Finch Dolostone Member of the Whitehall Formation is exposed at this stop. Three facies occur in a somewhat repetitive fashion: (A) Coarsely crystalline, laminated to slightly bioturbated dolostone (dolomitizad grainstone); (B) "pin-stripe" laminated cherty finely crystalline dolostone with rare burrows; and (C) dark grey to black dolomitic chert with dolomitized molluscan debris and dolomitic digitate algal stromatolites and dolomite "knots" (small algal structures??). The uppermost dolomitic chert bed thickens and thins on outcrop scale. The thicker portions of this bed appears to represent local "domes" or mounds formed by the thrombolites or algal stromatolites. Gastropod debris can be seen in one mound, perhaps representing shell material collected between cylindrical algal pillars.
The absence of direct evidence of subaerial exposure again makes exact environmental assignment quite equivocal. We suggest that the coarsely crystalline dolostones represent a "high energy" shallow subtidal/low intertidal facies; the "pin stripe" laminites a relatively lower energy muddy tidal flat facies. The dolomitic chert facies containing algal structures is probably shallow subtidal. We are again open to suggestions.
The origin of the silica for chertification of these rocks is also something of a problem. Rubin (1975) suggested that subaerial "silcretization" involving dissolution of terrigenous silicates and precipitation of opaline silica or quartz in a pedogenic setting on emergent tidal flats was a factor in chertification of Whitehall Formation carbonates. The fabrics indicating pedogenic silicification reported by Rubin are not present at this locality, however. A possible alternative is fabric-selective replacement of primary carbonate mud by silica derived from a biogenic source (sponge spicules) within the original sediment.

STOP 2A. Outpost fort east of N.Y. 8
Approximately 6 meters of variously burrowed, slightly dolomitic, thin to medium bedded bioclastic packstones are exposein this section. The dolomite occurs in shaly weathering wisps and laminae and in burrow fills. Abundant "Girvanella" algal oncolites (algal accretionary grains) are present in beds approx. 4 meters from the base of the section. Rounded dark calcite grains (abraded gastropod fragments) form the cores of the oncolites, and are scattered in other beds. Fossils are relatively abundant and best seen on bedding surfaces. Trilobite fragments, brachiopods, bryozoans, pelmatozoan plates, nautiloids and large Maclurites magnus are present. The relatively high faunal diversity, abundant lime mud and burrowing argue for a normal marine, low energy shallow subtidal carbonate environment. A possible modern analogue is found in the mixed mud and sand shelf to the west of the emergent Andros Island tidal flats, as described by Bathurst (1971) and Purdy (1963). The 5-10 cm thick beds of "oncolite conglomerate" and other more well-sorted grainstone beds may represent periods of storm winnowing of the bottom, with transportation of abraded sand from adjacent sand shoal environments (e.g. Locality 2B). The wavy, irregular dolomite laminae appear to result from post-depositional dolomitization of lime mud, followed by compaction and local pressure solution of calcite, producing irregular, clay- and dolomite-rich stylocumulate seams. Preferential dolomitization of burrows may be due to contrasts in porosity or permeability of burrow-fill versus burrow-matrix sediment. The burrow-fill sediment may have retained permeability longer during diagenesis, permitting pervasive dolomitization. This sort of fabric selective dolomitization is common throughout the Chazy and Black River Groups in the southern Lake Champlain Valley.

STOP 2B. Ledge immediately NE of gate to Historic Site
Cross-stratified coarse lime grainstones with bipolar crossbed dip directions are well-exposed near the entrance road. Siliciclastic sand grains (angular quartz and feldspar up to 2 mm in diameter) are locally concentrated along prominent stylolite seams. The carbonate particles are dominately subrounded, abraded pelmatozoan plates, plus gastropod and brachiopod fragments. Large Maclurites fragments and grainstone intraclasts are present on the upper bedding plane surfaces of the ledge.
We envision the environment of deposition of this facies as shallow subtidal wave and/or current reworked sand bars. Active transport of abraded grains may have been accomplished by tidal currents as suggested by the bipolar cross-beds. The lack of burrows and well-preserved fossils may be due to the inhospitable shiftng sand substrate. This environment may have been rather like the unstable sand shoal environments described from the Bahamas Platform by Bathurst (1971) and Ball (1967). The scale and style of cross-stratification present here are similar to that predicted by Ball from his studies of the bedforms and primary structures of the Bahamian sand bodies. Similar Chazyan facies in the Northern Champlain Valley contain abundant oolites (Oxley and Kay, 1959).

STOP 2C. Low Ledges on entrance road approx. 50 meters north of 2B
Brown weathering, slightly shaley dolostone exposed here contains small lenses and stringers of fossiliferous lime packestone. Trilobites, small brachiopods and Maclurites fragments are common. This exposure resembles the shelf lagoon facies of Stop 2A, although dolomitization is more pervasive.

STOP 2D. East point of British Fort, by horizontal water tank and south moat
Approximately 3 meters of thickly laminated limestone and dolostone is exposed in the southeast "moat" of the British Fort. The dominant facies here consists of alternating 0.5-2 cm thick laminae of limestone and dolostone - often termed a "ribbon rock". The limestone ribbons are mudstones and appear blue-grey on slightly weathered surfaces and as indentations on highly weathered surfaces. The more resistant dolostone weathers tan to brown. An erosional surface with 10-20 cm of relief is exposed near the base of the southwall. Abundant Maclurites shells occur in a shell bed on this surface. Lateral accretion cross-strata consisting of gently dipping ribbon rock are present above the erosional surface. Dolomitized burrows transect the limestone ribbons in the lower 1 meter of the section. On the less-weathered prominence on the SE corner of the moat, shallow scours containing a shell hash of brachiopods and gastropod debris are present, along with intraclasts of lime mudstone in dolostone and "Mexican Hat" structures (rolled intraclasts or pseudoclasts with a dolomitized burrow center).
We interpret this sequence as a tidal flat facies. The rhythmic limestone/dolostone "ribbon" fabric is interpreted as representing alternating slightly finer (lime mudstone) and coarser (dolostone) "tidal bedding" similar to that described by Reineck and Singh (1980) from the clastic mud/sand tidal flats of the North Sea. The Maclurites shell bed may mark the basal erosional level of a tidal channel, with the cross-stratified ribbon laminites forming by draping on the channelled surface. Variations in degree of burrowing record subtle differences in degree of subaerial exposure of the flat and/or reworking by tidal currents. Limited in situ faunal diversity is also expected in the stressed tidal flat environments. The absence of mudcracks and any indication of evaporite minerals suggests that we are seeing only the lower portion of a wet intertidal flat system preserved here.

STOP 2E. Enter Parade Grounds by barracks.
Around 1916, gunite was sprayed on the interior walls to protect the mortar from deteriorating. Starting in 1976, the N.Y. State Division for Historic Preservation began extensive maintenance, removing loose gunite, replacing rotted stones and repainting the stone walls.
In the outer wall of the first barracks, note at about eye level the stones that are nearly white-weathering. These are lime mudstones from the "Lowville" facies of the Orwell Limestone, exposed at Stop 2F.
The broad limestone outcrop west of the barracks is a cross-stratified lime grainstone with scattered subrounded quartz and feldspar sand grains. Trough cross-strata and "herringbone" co-sets of planar-tabular cross-strata are visible on the low vertical face. Large angular clasts of slightly dolomitic lime grainstones and Maclurites magnus shells are present on the uppermost bedding surfaces.
We interpret this facies as a current-dominated sand shoal environment rather similar to the exposures at Stop 2B.
Westward across the parade grounds there is a massive, bioturbated, brown weathering dolostone unit (similar to Stop 2C), overlain by 0.5 meters of very coarse-grained bioturbated, slightly dolomitic feldspathic quartz sandstone. This sandstone forms the summit of the Chazy Group (Crown Point Formation). The abundant angular quartz and feldspar granules in the sandstone suggest derivation from a relatively close granitic (Adirondack?) source terrane. These sands were apparently transported from the west during an interval of relative emergence of the carbonate platform and were briefly reworked in a shallow marine setting. The basal dolostone bed of the Black River is exposed immediately atop the sandstone.

STOP 2F - Moat Walls at North Entrance to British Fort
The section from here to locality I is within the Orwell Limestone. The basal beds consists of thick-bedded to massive lime mudstones with vertical spar-filled burrows (form - genus Phytopsis) and rare ostracodes. Fossil abundance and diversity increase in the overlying beds, with gastropods (Loxoplocus), corals (Lambeophyllum, Foerstephyllum) and brachiopods appearing. Grain size increases upsection, with sporadic appearance of intraclast grainstones and ripple cross-lamination. Overall this section is similar to the Lowville Limestone of the type Black River Group of the Tug Hill region. The facies pattern here suggests a progression from restricted (tidal or lagoonal?) mud flats (Phytopsis lime mudstones) to more open marine mixed mud/sand shelf environments.
The summit of the moat outcrop exposes a horizon of black chert nodules which can be traced laterally across the road to locality G.

Stop 2G. Ledges extending from service road to lake shore.
Watch for poison ivy!
These exposures closely resemble the Chaumont (House Creek Limestone of Fisher, 1977) facies of the Black River type section. Thick-bedded to massive richly fossiliferous lime packstones and wackestones document a normal marine, relatively low energy carbonate shelf environment. In addition to the forms mentioned earlier, the large stromatoporoid (calcisponge) Stromatocerium, the high-spired gastropods Hormotoma and Subulites, the nautiloids Actinoceras and Geisonoceras, plus bryozoans, brachiopods and pelmatozoan material are common. On some bedding surfaces, black chert nodules follow large horizontal burrows. The chertification here is post-depositional and involved dissolution and reprecipitation of siliceous skeletal material (sponge and radiolarian). The uppermost bed in this set of ledges is a black chert bed approximately 2 cms thick. This bed can be traced to the lake shore where a similar section can be seen. Glacial abrasion obscures much of the detail that is exposed on more weathered surfaces.

STOP 2H. Blocks and Quarry Walls by Lake Shore
The quarry was established in 1870 by the Fletcher Marble Co. in an unsuccessful attempt to find a source of "black marble" dimension stone. The quarry is reportedly only 1 meter or so deep. The narrow spit going north was built to load blocks on barges, but evidently no blocks were shipped. The quarried blocks consist of medium to thick-bedded fossiliferous packstones and wackestones with some ripple cross-laminated grainstone beds visible in the north quarry bench. Strophomenid brachiopods, bryozoans, pelmatozoan stems and fragments of the trilobite Isotelus are present. The environments represented here are similar to those at 2G. As we continue north and walk along the lake shore, more exposures of the upper part of the Orwell can be examined. The bedding surfaces contain abundant opercula of Maclurites logani, and scattered Forstephyllum, Lambeophyllum and Stromatocerium are found. The byssate bivalve Ambonychi is also present.
The transition from the Orwell to overlying Glens Falls Limestone is covered by beach gravels as we continue west along the lake shore.

STOP 2I. Exposures of Glens Falls ls separated by intervals of beach gravels
Stops 2I ,J, ad K - Series of exposures of Glens Falls Limestone separated by covered intervals of beach gravels
The westernmost outcrops are on Private Property beyond Locality K. Do not go onto that part of the shore (marked by fence and stone wall, plus the large dead elm tree).
The Glens Falls limestone consists of medium to thin-bedded lime packstones and wackestones with some well-laminated, fine-grained bioclastic grainstones. Many limestone beds show internal grading from coarse, fossil-rich bases to less fossiliferous, fine-grained tops. Thin shaley interbeds separate the limestone beds. Horizontal trails and burrows (including form-genus Chondrites) are common on some bedding surfaces.
Fossils are abundant and rather diverse. Trilobites (usually fragmental) include Isotelus, Flexicalymene and rare Cryptolithus; the brachiopods Sowerbyella, Rafinesquina, Dinorthis and Dalmanella; bryozoans Prasopora, Eridotrypa and Stictopora; plus orthocone cephalopods and pelmatozoan debris. Gastropods, which are so abundant in the underlying Orwell limestone are exceedingly rare in the Glens Falls.
The environment of deposition for the Glens Falls is a sub-wave base shelf. No shallow water features are observed and the graded limestone beds are evidently deposited by density/turbidity currents generated on adjacent, slightly shallower portions of the shelf. The Glens Falls here records the continuing deepening of the Middle Ordovician shelf that began with the deposition of the Phytpsis lime mudstones at Stop 2F. The shale interbeds and generally more argillaceous character of the Glens Falls document increase in terrigenous mud input, perhaps derived from the rising Taconic Orogenic complex to the east. Quartz and feldspar grains of volcanic origin are also common in insoluble residues of Glens Falls limestones, suggesting increased eruptive activity at this time.
The contrast in terrigenous content of the Chazy Group vs. Black River and Trenton Groups is noteworthy. Insoluble residues from Chazy Group carbonates contain abundant, coarse-grained, rather angular quartz and feldspar grains (e.g. Stops 2B and 2D) plus clay-size material whereas the Black River and Trenton Groups lack coarse sand-size grains and contain either volcanic quartz and feldspar (Black River and Trenton Groups) or clay plus volcanics (Trenton Group). This change is likely related to a shift in available clastic source from the slightly emergent cratonic basement to the west that was exposed during Chazy Group deposition to the rising Taconic volcanic/metamorphic complex to the east during Black River-Trenton Deposition.
Combining the environments of deposition with the time-thickness pattern of sedimentation, the Crown Point section takes on tectonic meaning. The Chazy sediments were deposited just about at sea level -- Girvanella and Maclurites. The Orwell was deposited in shallow sub-tidal conditions -- two corals, the grazing snail Maclurites, and probably the Stromatocerium. The Glens Falls was deposited in a more offshore setting.
A time-thickness graph for the Cambrian-Ordovician sequence of the Champlain Lowlands shows some interesting changes in slope. Sedimentation through the Chazy yields a concave-upward curve that shows a continued slowing of crustal subsidence. Then, starting with the Orwell, the crustal subsidence is greater than the rate of sedimentation, because the water deepens. Using the Middle Ordovician time scale of Churkin and others (1977), it is clear that Chazy sedimentation was scarcely 5 m/m.y.; the Orwell and Glens Falls accumulated at 30 or 40 m/m.y., and the thick shales accumulated at 200 m/m.y. (solid-grain thickness). This high rate is comparable to the rate of subsidence of the Australian platform entering the Timor trench (600 m/m.y.; Baldwin, 1982).
The Crown Point section, then, fits the picture of a cooling and slowly subsiding continental margin, through Chazy time. Then, the margin began collapsing as it tried to enter a subduction zone to the east, causing water to deepen rapidly. The section is a record of the very early part of the Taconic Orogeny, as the "east-moving proto-North American Plate 'felt' the presence of an approaching island arc" (Baldwin, 1982). collision that constitutes the Taconic orogeny.

A10: GLACIAL GEOLOGY AND HISTORY OF THE NORTHERN HUDSON BASIN, NEW YORK AND VERMONT
DAVID J. DE SIMONE
Department of Geology, Rensselaer Polytechnic Institute
Troy, New York 12180-3590
ROBERT G. LA FLEUR

A10: GLACIAL GEOLOGY AND HISTORY OF THE NORTHERN HUDSON BASIN, NEW YORK AND VERMONT

Ahead is the Batten Kill delta (310-320 ft Lake Quaker Springs).

NY 29 climbs the foreslope of the delta
NY 29 climbs the foreslope of the delta approximately along the axis of maximum thickness of gravel and sand. The banks along the road reveal the coarsening-up stratigraphy.

Water well logs record up to 65 ft of deltaic gravel and sand in the area.

STOP 1: Hollingsworth-Vose landfill.
Deltaic topset and foreset beds of the Batten Kill's Quaker Springs delta.

Deltaic gravel and sand, lake clay, and lodgement till are exposed.

Sediment thins rapidly southward
Water well logs and exposures indicate deltaic sediment thins rapidly southward through 30 ft to less than 10 ft. Notice the clay dug up from the pond farther along the road.

Groundwater flows out along the SG-clay contact
Groundwater flows out along the SG-clay contact at the heads of these gullies in Fryer Brook. We observed a pipe with a diameter just right for your arm at the head of one gully in 1977.

Notice the clay gullies as Wilbur Ave. crosses Fryer Brook.

Traversing the dissected clay plain and delta sand is gone
We're traversing the dissected clay plain and delta sand is gone so we cross Flately Brook and turn to the E.

Observe the shoreline profile of Lake Quaker Springs.
No beach sediment is preserved.

Till on your left and the lake clay plain on your right
Till on your left and the lake clay plain on your right with the tops of a few drumlins poking through.

Outwash fan into Lake Albany.
Meltwater flowed between Schuyler and Whelden mountains and deposited an outwash fan into Lake Albany. Minor exposures along the stream to your right (S) reveal gravel overlying clay and basal lodgement till.

STOP 2: Archdale kame moraine.
Exposure of clinoform sand and gravel beds in the moraine. Minor slumping of beds.

STOP 3: Nessle Bros Meats parking lot.
An excellent overview of the Archdale kame moraine deposited against the flank of Herrington Hill. This kame moraine band can be traced southward along the west side of Fly Swamp and across the valley at the southern end of the swamp where a head of outwash is recognized. Return N on WC 74.

Terrace-outwash gravel and sand
Note the terrace-outwash gravel and sand we're crossing with thin till and bedrock uplands to the north. At small rises and around curves in NY 29 till and bedrock are often exposed where the upland thin till and bedrock topography protrudes through the gravel and sand.

Old excavation into a kame ahead on your left.
Note the old excavation into a kame ahead on your left. This is associated with the Battenville moraine.

There is hummocky kamic gravel and sand ahead on your left.
NY 29 used up the till and gravel of the Battenville moraine where the moraine crosses the valley in Battenville.

Flat outwash and terrace gravel and sand
The fairly flat outwash and terrace gravel and sand we're crossing was deposited by meltwater from the ice margin

STOP 4: Tracy Bros excavation.
Horizontally-stratified gravel and sand overlies cross-stratified gravel and sand. Meltwater from the Carter Swamp ice margin deposited this deltaic sediment with sediment sources from the N and E. The Batten Kill has terraced the S end of this deposit.

STOP 5: Lodgement till exposure N side of NY 29.
Both lowland and highland lodgement till facies are similar in Washington County. Why? In contrast, the lodgement till of the Adirondacks is quite different from the Hudson lowland till.

A thick graded gravel bed was observed.
There is an excavation just to your right off of Ferguson Rd where a thick graded gravel bed was observed. How would you describe the sedimentary environment which produced this feature?

Notice the hummocky ice marginal sediment on your left.

Carter's Pond Wildlife Management Area. Lunch Stop.

Smooth rounded drumlinoid topography
Notice the smooth rounded drumlinoid topography developed in these thinly-veneered bedrock highlands.

Argyle sits atop a modest esker delta
The village of Argyle sits atop a modest esker delta deposited into Lake Quaker Springs. Lake clay nearly buried the delta.

STOP 6: Esker gravel and lake clay.
NY 40 rides atop this esker which fed the Argyle delta. Lacustrine clay has partly, and in places completely, buried the esker gravel and sand. Observe the deformed clay and gravel beds here. Is the deformation consistent with what you'd expect from melt-out of buried and/or adjacent ice or would you suggest a minor ice surge after deposition of the clay to account for the stratigraphy? Continue N on NY 40 along the crest of the esker.

STOP 7: Meltwater sediment complex
Harrington Farm excavations expose part of a meltwater sediment complex deposited at the base of the Taconic front along the eastern edge of Tamarack Swamp. The ice tongue responsible for the esker and delta through North Argyle and Argyle stagnated in the swamp. The major meltwater source for this sediment can be traced eastward along Safford Rd. to the town landfill. Coarser gravel and sand, horizontally-bedded and cross stratified, is exposed east of the road. The more distal portion of the delta fan exposed here contains laminated and ripple-laminated sand. A third excavation to the SW in the middle of the swamp contains the most distal and finest-grained sand, silt, and clay beds. The morphology of this last deposit suggests deposition in a tunnel or crevasse in the ice and indicates the rotting ice in Tamarack Swamp was inundated by Lake Quaker Springs.

STOP 8: Outwash gravel and sand in a significant local impoundment.
The north-flowing Mettawee River deposited this outwash gravel and sand in a significant local impondment. The exposed sand, silt, and clay beds accumulated in this Lake Granville whose elevation was approximately 420 ft. Clay is also preserved in the Mettawee valley from Middle Granville westward to Truthville with more silty sediment north of Raceville. There are some concretions in the clay here. Mildly deformed sediment particularly at the north end of the exposure probably resulted from meltout of abandoned ice in the lake. The Hudson ice lobe probably blocked the lower Mettawee valley at Truthville and contained Lake Granville. Retreat of this ice drained the lake and the Mettawee. River deposited its delta into Lake Quaker Springs.

This surface is the top of the Mettawee delta.

STOP 9: Winchell channel overlook.
Park as far off the road as possible and be careful of the traffic! The Winchell channel was one of three channels (the Durkeetown and Ft. Edward are the other two) which carried the outflow of Lake Fort Ann in the Champlain valley through the northern Hudson valley. The present surface stream, Big or Mill Creek, enters the channel from the south through a bedrock gorge (seen as a notch in the distance) and meanders across the channel bottom to Smith's Basin. The channel bottom consists primarily of lake clay while clay, till, and bedrock are all exposed on the flanks of the Winchell channel. This pattern generally holds for the other two channels as well except there is considerably more eroded bedrock along the primary Ft. Edward channel.

Bottom of the broad Durkeetown channel
We're crossing the bottom of the broad Durkeetown channel and will climb up its western escarpment. North-flowing Wood Creek and south-flowing Dead Creek are underfit streams in the bottom of the channel.

We're descending into the Ft. Edward channel.

The canal follows the bottom of the Ft. Edward channel.
Hudson-Champlain canal crossing - the canal follows the bottom of the Ft. Edward channel.

B1: THE NATURE OF THE EASTERN TACONIC CONTACT
PHILIP C. HEWITT
Department of the Earth Sciences
SUNY College at Brockport
Brockport, NY 14420
The purpose of this paper is to provide background information needed for both the full-day trip (A1) and the half-day trip (B1). The full day trip involves data from the entire paper while the half-day trip concentrates on the Taconic Problem primarily. However, to understand either day fully, the entire paper must be read. A separate Road Log for each trip is provided at the end of the paper.
The paper describes geologic features to be examined in area from Saratoga Springs, N.Y. to Manchester, Vt. A discussion and overview of the Taconic region and the "Taconic Problem" will be presented. Consideration will be given to both the sequential and fault hypotheses proposed for the High Taconic region.
The Taconic region is subdivided into the High Taconics and the Low Taconics based on the extreme difference in relief. The High Taconics are the mountains of Vermont, west of the Vermont Valley, with elevations of approximately 3000-4000 ft. The Low Taconics are the hills primarily in New York, west of the High Taconics, with elevations up to approximately 1500 ft. (Hewitt, 1961a). Lithologic and other distinctions will become apparent in the later discussion.

B1: THE NATURE OF THE EASTERN TACONIC CONTACT

STOP 1. Carbonate-Phyllite Contact At Sandgate
The exposure of green phyllite at this locality lies at the axis of a large anticline that lifts the base of the formation structurally. With favorable topography the lower parts of a formation may be exposed as at this locality. In a synclinorium, it is normal to expect that generally, the higher parts of the formations will lie deeper in the earth. When an anticline fortuitously is cut by erosion to expose lower and lower parts of a formation more data become available. In this case, part of the phyllite section responds to hydrochloric acid in a formation that normally has no calcareous beds.
After a general examination of the exposure a study of the lowest part of the formation visible here should be undertaken. This part is located at the southeast end of the outcrop. Note that the base of the exposure appears to be phyllitic and very much like the rest of the rocks here. If cold, dilute hydrochloric acid is applied, the lowest beds will effervesce. Visually one cannot see a difference between those beds that will react with the acid and those that will not. The question that must be asked is "What does this mean?" No other part of the phyllite reacts with acid. Carbonates are known to lie under the phyllite. Therefore, this is probably the contact of the carbonate and green phyllite. The nature of that contact at this locality is for you to decide.
Note also the depression to the south of this outcrop. Two possibilities exist here. The depression may be a combination of structure and topography. That is, the depression might lie in a syncline and therefore lower as a result of structure. This does not appear to be the case here because the anticline passes across the depression. It is also possible that the depression is the result of weathering of a carbonate exposed at the base of the phyllite. Return to cars and proceed southward.

Note folding along road.

STOP 2. Cook Hollow-Exposure Of Contact
It is wise, politic and intelligent to request permission to cross the property here to make the climb. The climb will involve a rise of 1200- 1400 ft. in elevation. Caution is important. Parts of the climb are steep. Some parts are slippery. A slow, steady climb with frequent stops is the best way to see the outcrops and arrive at the contact safely.
Each of the formations mentioned are described briefly in Table 1.
The drive from Rt. 7 crossed the upper Cambrian Danby quartzite and Clarendon Springs formation both of which contain quartzite and dolostone. These formations are not exposed along that traverse. After leaving the cars the traverse begins in the Shelburne marble. Exposures of these strata are best in the creek south of the traverse. It is best to begin the traverse by approaching the creek in order to examine the beds during the climb. However, higher parts of the climb may be difficult or nearly impossible in the creek since this is a landslide area. The easiest climb is on the north (right) side of the creek.
The contact of the Shelburne marble with the overlying Bascom-Beldens formation is at Table Rock. White marble, similar to that of the commercial marble in the Shelburne is also found in the Bascom-Beldens. However, most of the Bascom-Beldens formation is dolomitic marble which is blue-gray to black in color. Near the top of the dolomitic sequence, several hundred feet below the contact with the green phyllite are fossiliferous beds in the marble which contain fossils identical to those at the Covered Bridge on Rt. 313. These indicate an age of medial Ordovician (Trentonian). Beds containing fossils continue across the sequence almost to the contact.
Continued climb will reach a zone of carbonate and phyllite interbeds. Above this zone is a flat area or bench with the contact easily visible. Carbonate ends and the green phyllite continues to the top of Mt. Equinox.
No further description will be presented. It is up to the observer to decide what is seen here. Is this a faulted zone? Where is the fault? Between which strata? Is this a gradational contact? Where does one lithology end and the other begin? How would you describe the bed at the end of the carbonates and the beginning of the green phyllite?
It is up to you.
The descent is probably more difficult than the climb but it is much faster. Be careful.

B7: ROBERTS HILL AND ALBRIGHTS REEFS: FAUNAL AND SEDIMENTARY EVIDENCE FOR AN EASTERN ONONDAGA SEA-LEVEL FLUCTUATION
Thomas H. Wolosz
Center for Earth and Environmental Sciences
SUNY College at Plattsburgh
Plattsburgh, N.v. T2901

B7: ROBERTS HILL AND ALBRIGHTS REEFS: FAUNAL AND SEDIMENTARY EVIDENCE FOR AN EASTERN ONONDAGA SEA-LEVEL FLUCTUATION

STOP 1. Albrights Reef
Park cars along shoulder of road. Main part of reef lies to the right (east). Exposures along road are crinoidal sand/favositid flank deposits. Cliff face about 130 feet to east exposes rugosan constructed Inner Core.

STOP 2. Roberts Hill Reef.
Reef lies to the east of the road and makes up the entire northern portion of the hill. Old logging road marks approximate southern end of reef. Exposures to the west of the road and south of the logging road consist of post-reef growth flanks.
CAUTION: SOLUTION EXPANDED JOINTS ARE COMMON ON THE TOP OF THE HILL AND ARE COMMONLY FILLED WITH LEAVES. PLEASE WATCH YOUR STEP.

B8: DEGLACIATION OF THE MIDDLE MOHAWK AND SACANDAGA VALLEYS, OR A TALE OF TWO TONGUES*
Robert J. Dineen
New York State Geological Survey
The State Education Department
Albany, NY 12230
Eric L. Hanson
Dunn Geoscience Corporation
5 Northway Lane
North Latham, NY 12110
PURPOSE
The middle Mohawk Valley contains a record of the interaction between the Mohawk and Sacandaga glacial lobes, including evidence for several readvances. We will examine exposures in deposits that document these interactions and features.

B8: DEGLACIATION OF THE MIDDLE MOHAWK AND SACANDAGA VALLEYS, OR A TALE OF TWO TONGUES

You are on the Quaker Springs delta.

Kame moraine.

Follow North Street to the right (northeast), along south edge of Interlobate Moraine.

STOP 1: Broadalbin Town Landfill
This pit reveals the products of the ice-marginal environment. Here, the Yosts Readvance reached its maximum extent. The massive basal sands contain dewatering features (flame, dish, ball-and-pillow structures) .. These basal sands are sharply truncated, and overlain by fluvial sand with gravel that contains many reverse graded diamictons (flowtills).
Another pit, 0.4 m (0.7 km) west of Stop 1 shows evidence of more active ice. At this pit, a sequence of trough corssbedded sand is shared and overlain by a thick (1 to 3 m) diamicton.

Proceed along Lake Sacandaga sands to the intersection of NY Routes 29 and 30.

Perth Moraine and Perth Recessional Moraine
The upland that we drove over is the broad platform of the Perth Moraine. The low rise that we cross just before the stoplight is the Perth Recessional Moraine.

STOP 2. Perth Pit
We are on the Perth moraine, in a pit that cuts into the Perth Recessional Moraine. The base of the pit is trough-crossbedded outwash, overlain by 3 m of sand-matrix-supported diamicton. This till is overlain by trough-cross-laminated outwash sand and gravel. Wells nearby indicate that the pit is underlain by 30 to 40 m of interbedded till and sand. The till in this pit probably was deposited by the Yosts Readvance.

The Interlobate Moraine is on the right.
Follow the outlet of Lake Sacandaga to the long access road at the next Stop.

STOP 3. Rex Excavating
This exceptional pit has many instructive exposures. The base of the pit is bluish-gray clayey Mohawk till, overlain by 5 m of laminated fine sand, cut by trough-cross bedded sand and gravel. The sand and gravel is capped by 2 m of weathered till that is overlain by another sequence of lacustrine sand and prograding outwash. Till overlies this outwash, and is interbedded with lacustrine sand.
The multiple tills are the products of at least two readvances. The soil zone between the major sequences suggest several thousand years separated the two advances. Both sequences involved glacial ice overriding proglacial lacustrine and outwash deposits. The several tills above the soil zone probably were mudflows and lodgement tills of the Yosts Readvance. A similar exposure lies 1.1 miles to the east.

Cross the Cayadutta Spillway.

STOP 4. Twin Cities Sand and Gravel
This immense pit is over 300 m long and 7 m high.
It is the distal portion of the Interlobate Moraine, and contains distinct deltaic features. Both thrust and gravity faults are common, especially on the eastern end of the pit. A sandy diamicton caps the sandy deltaic sequence. Aeolian sand unconformably overlies the sandy till on the eastern end of the pit.

Drive up ice-contact slope and onto delta
Drive up ice-contact slope of the Interlobate Moraine and onto the Lake Gloversville delta.

Nice drumlins to the west, the Interlobate Moraine dominates the skyline to the southeast.

STOP 5. Mayfield Pits
This complex of pits is developed in an esker that drained the Sacandaga ice tongue. A subaqueous sand and gravel fan lies at the mouth of this esker. It was built by meltwater flowing in an ice tunnel into Lake Sacandaga. The esker is interbedded with lake sand.