NYSGA 1969
GUIDEBOOK
to
Field Excursions
at the
41st Annual Meeting of the
New York State Geological Association
May 1969
Stockton G. Barnett, Editor
Host:
Department of Physics and Earth Sciences
State University College
Plattsburgh, New York

A: SEDIMENTARY CHARACTERISTICS AND TECTONIC DEFORMATION OF MIDDLE AND UPPER ORDOVICIAN SHALES OF NORTHWESTERN VERMONT NORTH OF MALLETTS BAY
by
David Hawley
Hamilton College
Clinton, New York
INTRODUCTION
The central lowland of the Champlain Valley is underlain by Cambrian and Ordovician sedimentary rocks, bordered on the west by the Adirondack Mountains of Precambrian crystalline rock upon which Cambrian sandstone lies unconformably, and against which sedimentary rocks have been dropped along normal faults. The lowland is bordered on the east by low-angle thrust faults on which massive dolomite, quartzite, and limestone, as old as Lower Cambrian, from the east over-rode weaker Ordovician shale and limestone. The westernmost thrusts, the Highgate Springs thrust in the north, and the overlapping Champlain thrust in the south, trace an irregular line a few feet to 3 1/2 miles inland from the east shore of Lake Champlain. For most of the distance between Burlington and the Canadian border, the high line of bluffs marking the trace of the Champlain Thrust are composed of the massive, Lower Cambrian Dunham dolomite.
The shales, youngest rocks of the autochthonous lowland sequence, outcrop on most of the islands in Vermont, and the mainland between the thrusts and the lake. Although exposures on almost continuous shore-line bluffs are excellent, there are few outcrops inland because of glacial cover and low resistance of the shales to weathering. Fossils are rare in the older calcareous shale (Stony Point) and absent in the younger noncalcareous shale (Iberville). The lithic sequence was established almost entirely on structural criteria. Where it can be found, the Hathaway submarine slide breccia structurally over lies the Iberville

STOP 1. West shore of South Hero Island
West shore of South Hero Island, extending for one mile southward from the breakwater at Gordon Landing. The lower 215 feet of the Stony Point formation is exposed between the breakwater and the top of the Cumberland Head formation, 2900 feet to the south. In the next 2300 feet of shoreline, the upper 145 feet of the Cumberland Head formation is exposed. These sections are described in the text article. The south end of this section is cut off by a right lateral wrench fault striking N 59° W, dipping 79° NE. South of the fault the interbedded limestone and shale (about 79% ls., 30% sh.) have been mapped as the Shoreham member of the Glens Falls formation (Erwin, 1957) on the basis of lithology and the presence of Cryptolithus.

STOP 2. Road cut on east side of U.S. 2
Road cut on east side of U.S. 2 halfway between City Bay (North Hero Beach roadside park) and Carrying Place. This outcrop shows the interbedded laminated argillaceous limestone and calcareous shale typical of the middle section of the Stony Point formation. It lies close to the axis of a major, northeastward plunging anticline.

STOP 3. Middle point on north side of Carry Bay
Middle point on north side of Carry Bay, North Hero, 2000 feet east of Blockhouse Point. Typical Iberville cyclic bedding is exposed for about 1500 feet along this shore, extending eastward from the place where the access road meets the shore. From west to east are: an asymmetrical syncline, an asymmetrical anticline, and to the east of a covered interval is the east, overturned limb of a large syncline. These folds are in the axial area of a large, northeastward plunging, overturned syncline. Relationships of cleavage to bedding, axial surfaces, and direction of plunge are well shown. Small-scale current cross-lamination on some beds indicates southwestward flow.

STOP 4. Quarry in Iberville
Quarry in Iberville (mislabelled "gravel pit" on No. Hero Quad. map), 1.6 miles S 10° E from east end of North Hero-Alburg bridge. The beds are almost flat-lying, and only about 15 feet of section is exposed, but it is typical cyclic deposition, and the details are well shown, as described in the text.

STOP 5. Unnamed promontory
Unnamed promontory 1300 feet WNW of Coon Point, south Alburg. Upper-middle Stony Point beds measuring 258 feet (Hawley, 1957, p. 60, 89-91), with the base of the section on the southern tip of the point. It is composed of: olive-gray weathering, dark-gray argillaceous limestone, frequently silty, with light olive-gray weathering bands and laminae, in units of 3 inches to 40 feet, making up 96 percent of the section; light olive-gray weathering, dark-gray fine-grained limestone in beds of half an inch to 12 inches, making up 4% of the section. There are four thin (1/4 inch to 1 1/4 inch) beds of medium light-gray weathering, medium gray fine-grained crystalline limestone. Pyrite concretions are common. Trilobites (Triarthrus becki) are fairly common on a few bedding surfaces, and a few unidentifiable graptolite fragments were found. This stop is relatively inaccessible, may be cut off by high water, and may have to be omitted.

STOP 6. A small quarry, 3.3 miles north of Alburg - North Hero bridge
A small quarry, 3.3 miles north of Alburg - North Hero bridge on the west side of highway U.S. 2. Stony Point argillaceous limestone-rich section as described for Stop 5, including a fair scattering of Triarthrus becki.

STOP 7. Upper Iberville beds on the south and west sides of Clark Point
Upper Iberville beds on the south and west sides of Clark Point, at the south end of Hog Island (Vt. Hwy. 78 crosses Hog Island), west Swanton. A 304-foot section has been measured here (Hawley, 1957, p. 91-92). It is 97.8 per cent thin-cleaving noncalcareous shale (1 to 3 inch beds) with thin laminated dolomitic siltstone (1/4 inch to 2 inch beds, occasionally thicker) and homogeneous fine-grained dark gray dolomite, weathering yellowish-brown, in beds up to 14 inches, at intervals of 3 to 50 feet. Cyclic deposition is prominent here, with an estimated 1215 cycles in this section. The thin dolomitic siltstone beds commonly show cross-lamination and ripple drift, with southwestward currents indicated.

STOP 8. Upper Iberville beds in quarry
Upper Iberville beds in quarry (mislabelled "sand and gravel pit" on East Alburg Quad. map) 1800 feet north of Vt. Hwy 78 and 600 feet west of Campbell Road, northern Hog Island, west Swanton. The rock is similar to that described for Stop 7. The quarry exposes an overturned anticline, thrust faulted on the upper, eastern limb, with adjacent syncline immediately westward, also faulted.

STOP 9. Southernmost tip of St. Albans Point
Southernmost tip of St. Albans Point, on property of Camp Kill Kare. Northeastward plunging asymmetrical anticline with linked small syncline northwest of it, in Iberville noncalcareous and calcareous shale with dolomitic interbeds.

STOP 10. Between Camp Kill Kare's access road and the lake
Between Camp Kill Kare's access road and the lake, about halfway between the private cottages and the Camp buildings. There are 31 feet of white weathering, grayish-black chert in beds of 2 to 6 inches, dipping steeply (69° ) southeastward on the southeast flank of the anticline at Stop 9. Structurally overlying the chert beds is black siliceous argillite in which bedding is not apparent because of its irregular, chippy foliation. The argillite contains rounded pebbles (avg. 1 by 2 inches) of gray dolomite and fragments of chert. Some graptolites were found in the argillite, but smearing precluded identification. This is part of the Hathaway formation. It is likely that the chert beds here represents a larger mass involved in a submarine slide.

STOP 11. Hathaway Point, at the south end of St. Albans Point.
This is the type locality for the Hathaway formation. It has a matrix of pale-greenish-yellow weathering rock seen on a polished surface to be composed of small, irregular, curdled masses of greenish-gray to olive-gray argillite. Streamed and isoclinally folded in the matrix is black siliceous argillite similar to that associated with the chert beds at Stop 10. "Floating" in the matrix are small masses of grayish-black radiolarian chert which are commonly angular, as well as masses of bedded chert measurable in tens of feet. Fragments of dolomite and dolomitic siltstone occur in the western part of the Hathaway point exposure. Numerous slickensided tectonic shears are present in a variety of orientations. One 40-foot wedge between shears is composed of isoclinally folded calcareous and noncalcareous shale with occasional boudinaged masses of fine-grained limestone, resembling the transition beds at the base of the Iberville. Both of the islands east of Hathaway Point, in the middle of the bay, are composed of chaotically deformed argillite and chert. It is assumed that St. Albans Bay may lie over a deep synclinorium.

STOP 12. Lime Rock Point, on the southeast side of St. Albans Bay.
At the base of the bluff composed of the Beldens (Upper Canadian) crystalline limestone with buff-weathering dolomitic beds, there is a dramatic exposure of the Highgate Springs overthrust; lower Ordovician Beldens Limestone over upper Ordovician Iberville calcareous and noncalcareous shale with occasional beds of yellowish-brown weathering fine-grained dolomite and silty dolomite. At the base of the high, steep bluff about one half mile to the east is the Champlain overthrust, on which the lower Cambrian Dunham dolomite is thrust westward over the Beldens. South of Lime Rock Point the Highgate Springs thrust slice is overlapped by the Champlain thrust for two and a half miles. It reappears for four miles, and then disappears again under the Champlain thrust, southeast of Beans Point. This is as far south as the Highgate Springs slice can be traced.

STOP 13. Beans Point, east shore of lake in northwest Milton.
The Hathaway crops out intermittently for 1200 feet north from Beans Point. This is in a zone of intense deformation close to the Highgate Springs thrust, the trace of which is covered, probably about 600 feet back from the shore. The base of the steep bluffs 2000 feet back from the shore marks the trace of the Champlain fault, on which lower Cambrian Dunham dolomite has been thrust over Beldens crystalline limestone and dolomite of the Highgate Springs slice.
The Hathaway is composed of boulders and fragments "floating" in mashed argillite. The argillite is mottled olive gray to dark greenish gray to greenish black. On a polished surface cut perpendicular to foliation the mottled colors are seen to represent original bedding which has been folded most intricately, and sheared with no development of slickensides or breccia. The small-scale shearing has completely healed, and some minute fold crests merge into the adjacent bed, a streaming of one bed into the next with no sharp boundary. Included in the argillite are rounded fragments of moderate-yellowish-brown weathering, dark gray fine-grained dolomite and cross-laminated dolomitic siltstone, sub-angular to rounded, up to 4 by 7 by 20 inches in size. The long axes of the boulders are approximately parallel, plunging about 55° toward S 45° E. Foliation causes the argillite to split into irregular tapered chips. Thirty-six feet of cover separates the north end of the Hathaway outcrop from cyclic-bedded upper Iberville which lies overturned, dipping 46° northeastward.

STOP 14. Camp Watson Point, 3/4 mile south of Beans Point (Stop 13).
The core of a large, overturned syncline is exposed on the point, plunging 18° toward N 56° E. The overturned limb, dipping 29° southeastward, is exposed for 200 feet or more along the shore to the south. The rock is lower Iberville transition, with interbedded calcareous and noncalcareous shale, argillaceous limestone, and silty laminated dolomite.

STOP 15. Clay Point, between Malletts Bay and the Lamoille River
Clay Point, between Malletts Bay and the Lamoille River, east shore of lake. THIS PROPERTY IS POSTED, AND PERMISSION MUST BE OBTAINED. In the transition beds in the lower Iberville (interbedded calcareous and noncalcareous shale, with argillaceous limestone, argillaceous dolomite, fine-grained dolomite, and silty-laminated dolomite with current crossbedding) there is a small, overturned anticline cut by small thrust faults. The relationship of cleavage to bedding, plunge of the fold, identification of tops by cross-bedding, and the faulting make this a worthwhile stop for a structural geology class.

STOP 16. From Kibhee Point southeastward along the shore
From Kibhee Point (northeastern South Hero) southeastward along the shore for 2500 feet, is exposed the transition from Stony Point to Iberville formations. With a few minor rumples the dip is southeastward all the way to a deep gully and small bay which separate a steep bluff-point to the east from the shore northwestward to Kibbee Point. This bluff, 2800 feet SE of Kibbee Point is composed of Stony Point argillaceous limestone and calcareous shale, overturned and dipping 55° southeastward. Thus, the gully conceals the faulted core of an overturned syncline. The fault is very likely a thrust, east side up.
West of the gully is Iberville, about 90% finely cleaved noncalcareous shale, with interbedded silty cross-laminated dolomite. Northwest from here to Kibbee Point the proportion of noncalcareous shale and silty laminated dolomitic interbeds decrease and the proportion of calcareous shale increases. About 220 feet southeast of Kibbee Point the southeastward-dipping beds are massive calcareous shale (Stony Point fm.). About 900 feet south of Kibbee Point on its west shore the Stony Point beds still lower in the section are predominantly argillaceous limestone, interbedded with calcareous shale.

B: RECENT SEDIMENTATION AND WATER PROPERTIES, LAKE CHAMPLAIN
by
Allen S. Hunt and E. B. Henson
University of Vermont
INTRODUCTION
Purpose
Within the last few years a considerable amount of research has been done on Lake Champlain. The purpose of this trip is to show what type of work is being carried out on the lake and to report some of the findings.

STOP 1. First stop of west-east traverse
This stop, along with stops 2 and 3, will constitute a west-east traverse designed to show differences in thermal patterns, benthos, and sediment types across the lake. At stop 1, a bathythermogram will be taken to demonstrate water temperature differences with depth. A grab sample will be taken and sieved for macro-organisms, and a core sample will be collected. The sediments at this stop are organic muds which contain no gravel, less than 10 percent sand, and equal amounts of silt and clay. The mean phi size is about 8, the standard deviation 2.5 phi.

STOP 2. Middle stop of west-east traverse
A bathythermogram and core will be taken and a grab sample will be sieved for benthos. The sediment at this stop is described under "sediment properties" as a pebbly sandy clay. An average sample contains 25 percent sand and gravel, 10 percent silt, and 65 percent clay. The mean grain size is 8 phi, the standard deviation 4.5 phi.

STOP 3. Last stop of west-east traverse
A bathythermogram will be taken at this station to complete the traverse profile, the benthos will be sampled, and a plankton haul will be made. Water samples will be taken from selected depths and analyzed for alkalinity, pH, and dissolved oxygen. The sediments at this stop consist of organic muds. The mean grain size is 8 phi, and the standard deviation just over 2 phi. Sand makes up less than 5 percent of the sample with silt and clay equally divided among the remaining portion.

STOP 4. This is a shallow-water stop at the mouth of the Winooski delta.
Grain-size analysis has shown sediments to be about 90 percent sand, 10 percent silt, and 1 percent clay. The mean grain size is 2 phi, the standard deviation just over 1 phi. Note the absence of an interface on the sediment surface.

STOP 5. This stop is to collect sandy clay sediment.
The sandy clays have much in common with the pebbly sandy clays of stop 2 in that both are poorly sorted, and both have a high percent of sand and clay with only a small percentage of silt. The pebbly sandy clay and the sandy clay may be facies of the same sediment.

C: BEDROCK GEOLOGY OF THE SOUTHERN PORTION OF THE HINESBURG SYNCLINORIUM
by
Rolfe S. Stanley
Department of Geology
University of Vermont
INTRODUCTION
Purpose
The geology of west-central Vermont has attracted the attention of geologists since the early work of Hitchcock, et al. (1861), and Logan (1863), to mention only two. During this century notable contributions have been made by Perkins (1910), Keith (1923, 1932, 1933) and, in particular, Cady (1945, 1960). The mapping of Welby (1961) west of the Champlain thrust, and Stone and Dennis (1964) in the Milton quadrangle just north of Burlington, completes the present state of knowledge of the Hinesburg synclinorium and immediate surrounding areas (Fig. 1, inset map). These works are incorporated in the Centennial Geologic Map of Vermont (Doll, et al., 1961).
Among several major problems still rema~n~ng to be resolved is a clearer understanding of the effects of the Acadian and subsequent orogenies or disturbances on the structures of west-central Vermont. Inasmuch as rocks of Upper Ordovician through Devonian age are not present in western Vermont, it becomes most difficult to evaluate the relative importance of Taconic and younger events. Answers to this central problem with its many corollaries can hopefully be provided by detailed studies involving a combination of stratigraphic, petrologic, geochronometric, and structural approaches. It is the purpose of this trip to examine the geology of the Hinesburg synclinorium and to show how recent work may be helpful in answering these problems in the future.

STOP 1. Champlain thrust at Long Rock Point, Burlington
(Note: The Episcopal Diocesan Center has been kind enough to allow us to visit this locality. Please do not litter.) This locality is perhaps one of the finest exposures of the Champlain thrust in Vermont and Canada. Here the Dunham Dolomite (Conners facies) of Lower Cambrian age overlies the Iberville Formation of Middle Ordovician age. The thrust contact is sharp and marked by a thin discontinuous zone of breccia in which angular clasts of dolostone are embedded in a highly contorted matrix of shale. Slivers, several feet thick, of limestone are found along the fault and may represent pieces of the Beekmantown Group (Beldens Member of the Chipman Formation?). The undersurface of the Dunham Dolomite along the thrust is grooved by fault mullions which plunge 15° to the southeast (Fig. 3 diagram 1 and 2a). The average southeastward dip of the thrust is 10°.
A variety of minor structures are found in the Iberville Formation whereas joints are the only structures in the Dunham Dolomite. Faults and joints are oriented in a number of attitudes in the shale, but they have not been analyzed as yet. Many of these fractures are filled with calcite and grooved with slickensides. The minor folds in the shale are numerous, and are easily grouped into two age generations. The early folds have a well developed slaty cleavage which offsets the bedding and attests to differential flow parallel to the axial surface. Although only a few fold hinges are present, the slaty cleavage forms the dominant layering and is concordant to the undersurface of the Dunham Dolomite.
The younger generation consists of asymmetrical drag folds with short gently curved hinges and rather open profiles. The axial surface is rarely marked by cleavage but when it is developed, fracture cleavage, which is commonly filled with calcite, is typical. These folds deform the slaty cleavage of the older generation and hence are younger in age. The orientation of 59 axes with their sense of rotation is shown in diagrams 1, 2a and 2b of figure 3.
Slip line orientations The drag folds of the younger generation can be used to determine a slip surface and direction according to the method described by Hansen (1967, p. 390-397). The analysis assumes that these folds are in the truest sense drag folds and have formed by movement of one layer or zone over another. In this locality the drag folds in the shale presumably were formed by Dunham Dolomite moving over the Iberville Formation. Because the shale is highly anisotropic, consisting of thin layers of compact shale separated by thinner layers of extremely fissile shale, the folds are confined to zones several feet in thickness and are disharmonic in profile.
A slip plane and line were determined for three separate localities at Rock Point (Fig. 3, diagrams 1, 2a, 2b). For each place the 18 to 23 fold axes with their respective senses of rotation were plotted on a lower hemisphere equal area net. The great circle that best approximates the spatial distribution of axes defines the slip plane. In all the diagrams of figure 3, clockwise folds cluster along one part of the slip plane whereas counterclockwise folds cluster along the other. The bisector of the arc separating the two groups of folds is the slip line. The location of clockwise and counterclockwise arrows on either side of the separation arc determines whether the upper layers moved up or down along the slip line. In diagrams 2a and 2b (Fig. 3) the upper layers moved to the northwest along a line striking N 40 W for 2a, and N 54 W for 2b. In contrast the upper layers moved downward along a line striking N 86 E for the southern part of the Champlain thrust at Long Rock Point. (diagram 1, Fig. 3).
Discussion of Results The kinematic basis for this analysis has been worked out in such geologic environments as tundra and sod slides, glacial lake clays, lava flows and metamorphic rocks of all grades (Hansen, 1967; Hansen, et. al., 1967; Howard, 1968). It can be shown that the separation arc contains the movement direction of slip line and that the drag folds which locate this direction are a product of one movement event. One can further deduce the likely position of the principal axes of stress (σ1,σ2, σ3 by analogy to slip systems. σ2 would lie in the slip plane perpendicular to the slip direction. σ1 and σ3 would define the deformation plane which is perpendicular to the slip plane and parallels the slip direction.
σ1would be oriented approximately 45° from the slip plane in a direction permitted by the sense of shear indicated by the drag folds. The slip line would then parallel the direction of maximum resolved shear stress.
In all subsequent discussions σ1 is the maximum compressive stress, σ2 is the intermediate compressive stress and σ3 is the minimum compressive stress.
Diagrams 1 through 3 (Fig. 3) were determined at localities in the Iberville Formation beneath or just west of the Champlain thrust. With the exception of diagram 1, the slip directions indicate movement to the northwest (see diagram 7, Fig. 3 for synopsis). This direction is approximately parallel to fault mullions at Long Rock Point and slickensides on calcite-veneered surfaces at Shelburne Point (diagram 3) and, therefore, suggests that the deformation plane containing σ1 and σ3 for this phase of movement did trend northwesterly. A unique explanation for the easterly slip direction in diagram 1 is not known at present, but several possibilities will be discussed.

STOP 2. Shelburne Access Area
This locality is one of several places in the Monkton Quartzite that displays a sufficient number of joints, faults and feather joints for dynamic analysis. The location and orientation of faults and feather joints are shown on the geologic map (Fig. 4). At each numbered station the orientation, relative abundance, and surface features of approximately 10 joints were recorded. Diagram A of figure 5 shows the poles to 248 joints and diagram B shows four planes corresponding to the maxima in diagram A. The trend of each of the 10 feather joint arrays and their sense of shear are shown in diagram C.
Diagram D shows 13 faults with letters or arrows indicating the apparent movement. All faults trend approximately eastward (hereafter called cross faults) except for one that is striking to the north. As indicated on the map the dip slip displacement of each fault is only several inches whereas the strike slip displacement on one of these faults is 9 feet (fault 13, Fig. 4). (Faults are identified by the station number nearest them on the geologic map (Fig. 4)). Feather joint arrays adjacent to several cross faults further attest to strike slip displacement. This relationship is further emphasized by comparing diagram C and D (Fig. 5). Although Welby (1961, p. 204) assumes that all cross faults are normal faults, the above data definitely supports a wrench fault interpretation. Petrofabric analysis of quartz deformation lamellae in three samples (Ml, M3, M4) further confirms this conclusion (Fig. 6).
Dynamic Analysis Discussion of the stress configurations for each structure is based upon techniques and principles summarized by Friedman (1964). In stress analysis only the direction and relative magnitudes of the principal stresses can be evaluated. Furthermore, it is assumed that the manner in which these structures formed in nature is similar to the way analogous structures are formed in the laboratory.
Joints: The planes in diagram B (Fig. 5) corresponding to the maxima of diagram A can be interpreted in several ways. The acute angle between joints 1 and 3 is 80 degrees and the acute angle between joints 2 and 4 is 83 degrees.
Hypothesis 1: Joints 2 and 4 formed in the shear position. Joints 1 and 3 formed as extension and release joints respectively.
Hypothesis 2: Joints 1 and 3 formed in the shear position. Joints 4 and 2 formed as extension and release joints respectively. In both hypotheses σ2 is defined by the intersection of all joints. In hypothesis 1, σ1 would parallel joint 1 and trend to the east whereas in hypothesis 2 0σ1 would parallel joint 4 and trend to the southeast. Hypothesis 1 is preferred because joint 1 is commonly filled with calcite. Furthermore, this configuration is similar to the stress configurations deduced from the other structures (Fig. 6).
Feather joints: The 10 feather joint arrays in diagram C (Fig. 5) with their respective senses of shear indicate that σ1 is oriented east-west. σ3 is oriented north-south and σ2 is oriented vertically. Because the dip of the feather joint array could not be measured, the inclination of the principal stress axes could not be pinpointed. Although the principal stress directions are not as accurately known for feather joints as they are for other structures, their symmetrical relationship to the cross faults support a wrench fault interpretation and thus suggest that those faults trending north of west are left lateral whereas those trending north of east are right lateral.
Wrench Faults: The apparent vertical movement on all faults trending north of west is up to the north. This movement can be realized on left lateral wrench faults if σ1 dips more steeply to the east than the bedding. Those faults trending north of east that are downthrown to the north would then be right lateral wrench faults.
The apparent vertical movement of faults 4 and 13 trending north of east is up to the north. These faults are right lateral wrench faults if the movement on 4 is assumed to be the same as the displacement of fault 12 by 13. The horizontal and vertical components of the actual movement at these faults could be caused by σ1 trending westward and dipping eastward more gently than the bedding.
North-South Fault: This fault cuts several of the wrench faults and hence is younger in age. It could result from the following two stress configurations: Hypothesis 1: If the fault is a normal fault downthrown to the west, then σ1 would be vertical or steeply inclined to the north so as to produce the right lateral movement. σ3 would trend eastward or dip gently westward. σ2 would trend northward.
Hypothesis 2: If the fault is a wrench fault, then σ1 would trend northeasterly. σ3 would trend northwesterly and σ2 would be approximately vertical.
Quartz Deformation Lamellae: Approximately 380 deformation lamellae from 3 oriented samples have been measured from this outcrop. For each sample 100 (50 for M4) quartz grains were measured from each of three mutual perpendicular thin sections. For each grain the orientations of the c axis and deformation lamellae (if present) were measured. The results were analyzed using methods described by Carter and Friedman (1965), and Scott, et al., (1965). The deduced orientation for σ1,σ2, and σ3 are shown in figure 6. In M3 and M4, 01 lies in the bedding and 02 appears to be equal to 03 in magnitude. In Ml σ1 is inclined 40° to the east, σ2 dips 50° to the west and σ3 trends northward and is horizontal. Although these orientations are not parallel in all samples, they are consistent with the stress positions deduced from the megascopic structures and support the conclusions on the cross faults and joints.
Structural and Stress History Based on the above information it is possible to develop a structural history for this outcrop. This sequence is divided into the following three phases.
Phase 1: During this time all the wrench faults formed except fault 13, 4 and 10 (north-south fault), σ1 was inclined more steeply to the east than the bedding so that faults trending north of west are upthrown to the north and faults trending north of east are downthrown to the north. σ3 was oriented northward and σ2 was inclined steeply to the west.
Phase 2: During this time faults 13 and 4 developed with σ1 either horizontal or inclined more gently eastward than the bedding. This orientation permitted the right lateral faults (13 and 4) to be upthrown to the north. It should be emphasized at this point that the change in orientation of σ1 relative to the bedding in the Monkton Quartzite can equally be attributed to a rotation of the bedding within a stress system of constant principal stress orientation.
Phase 3: During this time the north-trending fault developed and can be interpreted as a normal, wrench, or reverse fault.
The feather joints and deformation lamellae are thought to have formed during phase 1 and 2, although definite evidence for their timing is lacking at present. The formation of the joints shown in diagram A and B in figure 5 could well have spanned the first two phases.
Relationship to the Champlain Thrust Wrench faults are commonly associated with thrust faults. Both can be related to the same σ1 direction and only require a switch of σ2 and 0σ3 in the stress configuration during thrusting to develop wrench or tear faults. In the same manner the small wrench faults in the Monkton Quartzite are thought to bear the same relationship to the Champlain thrust and as such suggests that other cross faults shown on the Geologic Map of Vermont (Doll, et al., 1961), may also be wrench faults.
The different stress orientations deduced at Long Rock Point (stop 1) and the Shelburne access area suggest several explanations. It is possible that they formed under the same stress system but have assumed their present orientation by subsequent deformation. Alternatively, they could have formed at different times under stress systems of different orientations. Future work will resolve this problem.

STOP 3. Winooski Dolomite in fault contact with Monkton Quartzite
This locality is a fine exposure of the Winooski Dolomite in fault contact with the upper portion of the Monkton Quartzite. The bedding in both these units dips gently eastward. The most conspicuous of several northeastward-trending faults is downthrown to the north placing the Winooski Dolomite in fault contact with the upper portion of the Monkton Quartzite south of the fault.

STOP 4. Shelburne Falls just southeast of the village of Shelburne
The Danby Formation dips gently eastward at this locality and is cut by several sets of joints. Ripple marks of varying sizes, cross beds and fossil burrows are well displayed in the quartzite and sandy dolomite on the west bank of the river. Current directions based on current ripples in the upper layers along the southern part of the exposure indicate flow to the southeast (S 10 E to S 40 E) whereas current directions based on cross bedding in the lower layers exposed near the falls to the north indicate flow to the north and west.

STOP 5. Jones Hill
This stop is located just west of the Champlain thrust and shows several large folds and minor thrusts exposed in the Iberville Formation. A lamprophyre dike, striking N 78 W and dipping 75 degrees to the northeast, is exposed in the southern part of the outcrop. The laccolith of syenite on Barber Hill is located approximately a mile southeast of here near the village of Charlotte.
The orientation of fold axes, slaty cleavage and faults is shown on figure 7; most of the faults are thrusts dipping eastward or southeastward at gentle to moderate angles. As shown on plate 1 the trace of the Champlain thrust is sinuous and offset at several places in the area. Welby (1961, Plate la) shows normal faults at each of these places but the orientation of bedding, particularly between Jones Hill and Pease Mountain, suggests that the eastward reentrants can be explained equally well by anticlines plunging gently to the east. Minor folds with this orientation are present on the north side of Jones Hill.

STOP 6. A short traverse through the fields north of the road.
This stop will consist of a short traverse through the fields north of the road. The Clarendon Springs Dolomite, the Shelburne Formation, and the Cutting Dolomite will be crossed. If time permits the traverse will be extended northward into the Bascom Formation. At least two generations of folds are present in this area. Axes of the earlier generation plunge to the southeast, east and northeast and possess a well developed axial surface cleavage which commonly dips eastward except when it is deformed by folds of the younger generation. The slip line orientations of diagrams 4 and 5 (Fig. 3) were determined from drag folds of the earlier fold generation at localities 4 and 5 on figure 1. These slip lines are almost parallel to those to the west of the Champlain thrust discussed under stop 1 and, therefore, strongly suggest that they may have formed contemporaneously as a result of the same stress system. The younger generation of folds plunges northward and folds the cleavage of the earlier fold generation.

STOP 7. Hinesburg thrust northwest of Mechanicsville
This locality is one of the finest exposures of the Hinesburg thrust. The Bascom Formation forms the lower plate and the argillaceous facies of the Cheshire Quartzite forms the upper plate. Minor folds can be found in both these units. Inasmuch as only 4 folds could be found in the Bascom Formation little significance can be attached to southwestward movement direction shown in diagram 6 (Fig. 3).

STOP 8. The Bascom Formation
The Bascom Formation crops out on several small hills just west of Brownell Mountain. To the east the Bascom grades into the Brownell Mountain Phyllite, a member of the Bascom Formation only recognized in the Hinesburg synclinorium. This stop may be cancelled if insufficient time is available.

D: THE LATE PLEISTOCENE OF THE CHAMPLAIN VALLEY, VERMONT
W. Philip Wagner
Department of Geology
University of Vermont
Burlington, Vermont
The existing knowledge of Pleistocene events in the Champlain Valley can be discussed in terms of glacial stratigraphy, areal distribution of glacial deposits, and water planes of Lakes Vermont and "New York", (this paper) and the Champlain Sea. The purpose of this field trip is to examine new evidence of glacial and post-glacial events as recently deduced from field study of the Champlain Valley between Burlington and Middlebury, Vermont.
Included in the list of references are recent papers which pertain to the Pleistocene and Recent history of the Champlain Valley. The topographic quadrangles, in order of their first appearance on the field trip, are as follows: Burlington; Fort Ethan Allen; Essex Junction; Mount Philo; Hinesburg; Bristol; Monkton. Acknowledgement is made to Chester A. Howard, Jr. and William R. Parrott, Jr. for data on Stop 16, to Howard for information about surficial deposits near the mountains north of the Winooski River (Fig. 1), to Robert Switzer for field assistance in 1967 and 1968, and to Allen S. Hunt for a review of the manuscript. The work upon which this paper is based was supported in part by funds provided by the U. S. Department of Interior as authorized under the Water Resources Research Act of 1964, Public Law 88- 379.

STOP 1. Champlain Sea beach (No.1, Figs. 1 and 2)
Exposures in gravel pits on both sides of barn show excellent beach structures and marine mollusks.

STOP 2. Lake New York beach-spit and delta (No.2, Figs. 1 and 2)
Gravel pits are in beach material; slightly lower bench to west is composed of deltaic sand which correlates with No.4, Figures 1 and 2.

STOP 3. Lake New York beach (No. 56)
One of the best developed beach landforms known in the area; terrain immediately east of beach is lake clay and west of beach is a lower level Lake New York delta. Note dunic(?) landforms between stops 3 and 4.

STOP 4. Fort Ann delta (correlative with No. 57)
Gravel pit shows channel structures characteristic of deltas in this area.

STOP 5. Oak Hill outlet channel (No. 68)
Gravel pit in channel bottom shows very coarse, poorly sorted gravel; outlet drained a Winooski Valley Lake in post-Coveville (?) time and therefore proves (?) that ice blocked the Winooski Valley during Coveville time.

STOP 6. Ice-contact delta (No. 59)
Numerous gravel pits in vicinity show progressively finer material from stop 5 to stop 6 where cross-bedded fine gravel, sand, and silt are exposed in pit; ice-contact nature of delta is suggested by poorly sorted gravel in nearby vegetated area to southwest; delta was apparently formed by Oak Hill channel water drainage into local lake impounded by continental ice.

STOP 7. Fort Ann bench (No. 27)
Road cut exposes coarse, poorly sorted gravel underlying (?) boulder-strewn (lag?) bench on hillside. A problem exists here in that the topography and the lag (?) suggest an erosional environment whereas the road cut indicates a depositional environment. Possibly mantle material (see text) has been modified by wave action.

STOP 8. Hummocky dead ice terrain (No. 43)
Stop is at gravel pit showing poorly sorted character of deposit; ice contact structures are visible in places in the vicinity from time to time.

STOP 9. Ice-contact delta?
This is a brief photography stop. Large scale cross-bedding is in kame terrace, delta, or ice-contact delta(?). The last named possibility is favored here.

STOP 10. Kame terrace
Gravel pits in vicinity show characteristic ice-contact features.

STOP 11. Pre-Coveville (44, 45), Coveville (46), and upper Fort Ann (47) delta
STOP 11. Pre-Coveville (Nos. 44 and 45), Coveville (No. 46), and upper Fort Ann (No. 47) deltas; 3 miles southeast of Hinesburg along Route 116; deltas were constructed by water from a local Winooski Valley lake which drained through an outlet channel (No. 67) at the divide between Hollow Brook and Huntington River; gravel pits show coarse gravel with large scale foreset bedding and less obvious topset bedding in places.

STOP 12. Coveville (No. 50) and upper Fort Ann (No. 51) deltas
The village of Bristol is located on the Coveville delta and the upper Fort Ann delta just west of Bristol; gravel pits show features similar to those at stop 11.

STOP 13. Lacustrine sediment veneered hummocky dead ice terrain; No. 53
Gravel pit exposes ice-contact material overlain by and interbedded (?) with lacustrine sediment; features suggest glacial and lacustrine sedimentation in close proximity.

STOP 14. Shoreline features of Lakes Fort Ann and New York (Nos. 16-22)
Southwest side of Mount Philo; a spectacular succession of six wave-cut benches and one beach-spit.

STOP 15. Two(?) till locality
Stewart (1961a, Stop 6) reports two till units with intervening lake sediment. The present investigation showed complex vertical and horizontal variations. At the east end of the exposure occurs (bottom to top): gray till (25 feet); till or gravel (30 feet); slumped lake clays. At the west end: gray till (25 feet); lake sediment (25 feet). At the middle of the exposure as many as five till units with intervening lake sediment have been counted. Lateral relationships are difficult to determine due to the steepness of the exposure but facies changes are likely.

STOP 16. Two(?) till locality
Stream bank exposures of a lower gray till and upper brown till; Stewart's (1961a, Stop 4) type locality for the Shelburne (gray) and Burlington (brown) tills. At the time of this writing, fabric and clay mineralogy analyses are being made. This information will hopefully be available for field trip presentation.

E: STRATIGRAPHY OF THE CHAZY GROUP (MIDDLE ORDOVICIAN) IN THE NORTHERN CHAMPLAIN VALLEY
Frederick C. Shaw
Herbert H. Lehman College
Bronx, New York
The Chazy Limestone (the oldest Middle Ordovician Group of the Champlain Valley) was first named by Emmons (1842) from exposures 15 miles north of Plattsburgh at Chazy, New York. Here and elsewhere in the northern Champlain Valley (Fig. 1) the unit outcrops on a variety of normal fault blocks. Given the low dips and heavy cover, Chazy stratigraphy is most easily understood from various shore outcrops around Lake Champlain. Valcour Island, southeast of Plattsburgh, offers perhaps the best section of the Chazy, and has been intensively studied (Raymond, 1905; Hudson, 1931; Oxley and Kay, 1959; Fisher, 1968; Shaw, 1968). The Isle La Motte, Vermont, exposures to be covered in this trip and trip Fare those studied by many of the same authors and, in addition, display the lower contact of the Chazy with the underlying Ordovician dolostones of Canadian age.
In the northern Champlain Valley (Valcour Island and north to the International Boundary), the Chazy Limestone (now Group) consists of about 800 feet of quartz sandstones, calcarenites, dolomitic calcilutites and biohermal masses (Fig. 2). Three formations, Day Point, Crown Point, and Valcour, in ascending order, were proposed by Cushing (1905) and have persisted to the present, albeit with some controversy (Fisher, 1968; Shaw, 1968). Oxley and Kay (1959) further subdivided the Day Point and Valcour into members, those of the Day Point (Head, Scott, Wait, Fleury) coming from southern Isle La Motte in the area to be visited. Shaw and Fisher experienced difficulty in using the Valcour subdivisions outside of their type areas at South Hero, Vermont.

STOP 1. The Head, Isle La Motte, Vermont
PLEASE NOTE: STOPS 1 AND 2 ARE ON PRIVATE PROPERTY WHICH WE HAVE SPECIAL PERMISSION TO ENTER. DO NOT SMOKE IN THE FIELDS, KNOCK OVER FENCES, ETC. OTHERS MAY WANT TO RETURN TO THIS CLASSIC LOCALITY AFTER YOU.
Lakeshore outcrops of the Providence Island Dolostone (Lower Ordovician) and the Day Point Formation (Chazy Group). Dip of both units several degrees to the north. Contact well-exposed and at least locally unconformable. Locality discussed by Shaw (1968), Erwin (1957). Section measured and described by Oxley and Kay (1959).
Approximately 40 feet of Providence Island Dolostone is exposed, being very fine-grained, massive, thinly laminated, am unfossiliferous. Mudcracks and a few ripple marks complete the picture of a unit deposited in very shallow water. Following Laporte (1967), the environment of formation was probably supratidal, closely paralleling modern day environments of dolomite formation described from Florida and the Bahamas. No detailed petrologic work has been done on this unit. In the absence of fossils, the age of this unit is not known. The underlying Fort Cassin Limestone (not exposed here) is known to be Late Canadian.
The Chazy Group begins here with about 20 feet of quartz sand and siltstones together with minor amounts of greenish shale (Head Member of Oxley and Kay, 1959). Ripple marks and cross-bedding are common. The fossils consist primarily of 'fucoids' (probably recording a variety of trails, worm tubes and the like) and Lingula. The succeeding Chazy unit (Scott Member of Oxley and Kay) consists of about 40 feet of echinodermal lime sand, cross-bedded in some places. Brachiopods (Orthambonites?) and indeterminable trilobite scraps are the chief recognizable fossils. The overlying 15 feet of quartz sandstone (Wait Member of Oxley and Kay) appears very similar to the initial sandstone.
This second sandstone is followed by a thick (115 feet) lime sand (Fleury Member of Oxley and Kay) which occupies most of Scott Point and The Head south of the road. Much of the unit is composed of echinoderm fragments, although little is known about the actual morphology of the creatures involved. Both the fragmental nature of the fossils and the frequently observed cross-bedding argue for considerable agitation of the ocean bottom.

STOP 2. Upper Fleury Member of Day Point Fm and overlying Crown Point Fm.
Upper Fleury Member of Day Point Fm and overlying Crown Point Fm. 200 yards south of the right angle bend in the road is locality R 25 (Shaw, 1968) which yielded 12 genera of trilobites, including Sphaeroxochus and Ceraurinella, from a particularly coarse pocket in the upper Fleury lime sands. Gastropods (Raphistoma) and brachiopods (Orthambonites?) are also present. This same stratigraphic level elsewhere, particularly 1 mile to the NE, displays spectacular bryozoan bioherms and the very early tabulate coral Lichenaria (Pitcher, 1964). These will be viewed on Trip F.
About 50 yards north of the road at this same stop, the silty, Maclurites-bearing limestones of the Crown Point appear. The actual contact with the Day Point is not visible but the lithologic change is evident. The Crown Point here contains several modest bioherms which have not been studied in detail. The earliest known stromatoporoids (Pitcher, 1964) are known to be important reef builders nearby in this unit and doubtless are dominant here as well (see Trip F).

STOP 3. Fisk Quarry
Middle Crown Point Formation, consisting of fine-grained, dark, silty limestone with buff-colored dolomitic partings. This is 'typical', non-reef Crown Point lithology. However, in the quarry wall and some of the cut blocks, small reeflets can be seen. These are assumed to be largely stromatoporoids and calcareous algae, although they have not been studied as intensively as the reefs at the same horizon to the east (Trip F). Evidently, these reef masses could grow at some depth in relatively silty waters. The mechanism of their establishment thus does not appear to be tectonic. Maclurites (large gastropod, rare) and a few trilobites and brachiopods may possibly be collected from the limestone, although they are not abundant.

STOP 4. Sheldon Lane
Upper Crown Point and Valcour Formations; dip north several degrees. Locality R3 of Shaw (1968) and "Road to Little Monty Bay" locality of Raymond and others.
South of the road, a very low-dipping section of Crown Point and Day Point extends for almost 2 miles across fields. The transition between the two units is similar to that on Isle La Motte. Bioherms appear not to be present in the Day Point in this area. The Crown Point, however, is only about 100-150 feet thick here, being composed largely of biohermal masses. These can be seen just south of the road. Just north of the road, in and around the abandoned quarry, are exposed bioherms usually classified as basal Valcour. They are characterized by somewhat more silt than the reefs south of the road. Similar reefs on Isle La Motte have been classed by Pitcher (1964) as having a higher percentage of bryozoan and algal components than the Crown Point reefs. Billingsaria (tabulate coral) may also be important here.
Impressive cephalopod and trilobite faunas have come from the Valcour reefs here, including Glaphurus (trilobite, Pl. 1, Fig. 4) and large asaphids, illaenids and ceraurids (trilobites). Shaw (1968) has discussed the restriction of some of these forms to the reef environment. Most of the fossils appear in fine lime mud which apparently was trapped in channels and pockets in the reef framework. Lime sands of pelmatozoan origin drape the reefs.

STOP 5. Abandoned quarry of International Lime and Stone Company
This is the uppermost part of the same section covered at stop 4 and shows well the contact of the Valcour with the overlying Black River Group (see also Fisher, 1968, Fig. 25). The upper Valcour, here, probably equals the Pamelia (lowest Black River), and is a shaly dolostone bearing Rostricellula (brachiopod, Pl. 1, Fig. 4). The contact with the overlying Lowville Limestone, a massive, gray limestone is gradational. The early horn coral Streptelasma is present in this unit, although possibly not here. The Isle La Motte appears correlative to the Chaumont west of the Adirondacks.

F. THE PALEOECOLOGY OF CHAZYAN (LOWER MIDDLE ORDOVICIAN) "REEFS" OR "MOUNDS"
Robert M. Finks
Queens College
Flushing, N. Y.
and
Donald F. Toomey
Pan American Petroleum Corporation
Tulsa, Oklahoma

STOP 1. Walking tour of LaBombard pasture
The walking-tour will start at the north end of the picnic ground and trailer camp on the north side of Wait Bay in southeastern Isle La Motte. It may be reached by following the main north-south road down the center of Isle La Motte to its southern end, turning left (east) to the trailer park entrance, and then turning left (north) up the hill to the picnic ground. Please note that the entire trip is on private property, and that permission must be secured from the landowners for visits.
Cross the fence and walk north to the bare exposures of the Lamottia biostrome in the Fleury Member of the Day Point Formation. CAUTION! DO NOT STEP INTO SOLUTION-ENLARGED JOINTS. SOME ARE PARTLY CONCEALED BY VEGETATION. WALK ONLY ON BARE ROCK SURFACES. THE JOINTS ARE OVER A FOOT DEEP.
The hemispherical to discoidal heads of Lamottia are closely packed in a calcarenite matrix. Joints offer an opportunity to observe their orientation in section. More than half are overturned over much of the area. Many are broken. The proportion of broken ones increases to the north and east, where the biostrome passes into calcarenite with ever fewer and smaller fragments of Lamottia. In the central area of the exposure there are belts some 10 feet wide in which fragmentation, proportion of over-turned specimens, and quantity of calcarenite matrix, are higher than elsewhere. These may represent surge channels. In the peripheral area to the northeast one may see much laminar Batostoma chazyensis surrounding the Lamottia fragments. This is the type locality for the genus Lamottia Raymond, 1924. Although Raymond's description of this bed as the "world's oldest 'coral reef" may be disputed, it still seems to be unchallenged as the world's oldest occurrence of corals of any kind.
Walk northwestward upsection, so far as fence lines, cultivated fields, and vegetation permit. DO NOT DISTURB FENCES OR LEAVE GATES OPEN! NO SMOKING WHILE WALKING THROUGH THE FIELDS; THERE IS A DANGER OF FIRE. ALSO, PLEASE KEEP OFF CULTIVATED GROUND.
At about 2000 feet N 45 W of the Lamottia outcrop, we will find small mounds of Batostoma chazyensis at the top of the Day Point Formation. They tend to show a N·S alignment, the zoaria are mostly branching rather than laminar. Possibly this is a deeper water environment than that of the Lamottia biostrome.
Continue to walk northward to a small dirt road, then walk west along it to a T-junction with a larger dirt road. Turn left and follow it southwest to a house and barn on the right. We will enter a gate into the large pasture behind the house and barn. Mr. Ira LaBombard, the present owner of the property, has kindly given us permission to enter his pasture to study the reefs in the Crown Point and lower Valcour Formations. He has requested, as a condition of permission, that NO SPECIMENS WHATEVER be collected. PLEASE RESPECT THIS ORDER. We will have an opportunity later in the day to collect from these same beds at another locality. The fossils are so beautifully displayed here that relationships may be seen without disturbing the rock. They may be photographed very advantageously on the glacially polished surfaces.
The reefs exposed here are mainly in the Crown Point formation and are the ones intensively studied by Pitcher (1964). You may examine contemporaneous reefs by walking northeastward along strike. You may examine successively younger reefs by walking northwestward upsection (slip is about 100 NW).
The reefs are exposed as mounds of light rock. The calcarenite between the reefs, and filling the channels in the reefs, is nearly black. The reefs outcropping nearest the fence were mapped by Pitcher as his Assemblage A, consisting of the stromatoporoid Cystostroma and the alga Solenopora. Those beyond to the northwest, and covering most of the pasture up to a distinct linear rise in ground, belong to Pitcher's Assemblage B. These show interesting variations from reef to reef as well as changes in faunal distribution from flanks to tops of the mounds. The fauna consists of the stromatoporoid Pseudostylodictyon eatoni, the lithistid demosponges Zittelella varians and Anthaspidella sp., the tabulate coral Billingsaria parva, the bryozoan Batostoma chazyensis, and the calcareous algae Solenopora, Sphaerocodium and Girvanella.
The fossils may be identified readily on weathered surfaces as follows:
1. Pseudostylodictyon eatoni: Large whitish masses with fine, dark laminae forming concentric patterns about centers an inch or two apart. These concentric patterns represent the mamelons and their small size is characteristic of the species.
2. Zittelella varians: Circular, dark gray bodies two to three inches in diameter, with a central circular light area representing the matrix-filled cloaca, and radial light areas, or ovoid dots, a few millimeters wide, representing the canals. In longitudinal section, the sponge is conical, and oblique sections will show the expected intermediate shapes. Some specimens have an irregular outline in cross section.
3. Anthaspidella sp.: Similar to Zittelella in color and texture, but shaped like long sinuous bodies, an inch or so thick and several inches long, when seen in cross section. A surface view of the sheet-like sponge shows a somewhat irregular mass with out a cloaca. The complete sponge has a short stalk, the whole being shaped somewhat like a distorted cake-plate. The open, "spongy" texture may help when shape fails. Needless to say, the shape and geometric arrangement of the spicules in thin section is necessary for a secure identification. Not every shapeless mass is a sponge.
4. Billingsaria parva: Small, black, oval patches, a few inches across. The dark color is very distinctive. Close inspection with a hand lens will reveal the stellate outlines of the corallites with their characteristic septal ridges.
5. Bryozoa: These weather white, either as small, branching twiglets, or as laminated sheets. Identification requires thin sections, but the outlines of the zooecia are usually visible on the weathered surface and suffice to identify it as a bryozoan.
6. Solenopora: White concentric circles, often sparry. A few inches across. This is the most common form of Solenopora seen on the reef surfaces.
7. Girvanella: Small black ovoid bodies, less than an inch in length. These are oncolites, or algal-coated shell fragments.
8. Maclurites magnus: Large coiled shells a few to several inches across. No septa. The shell substance is white in cross section.
At the rise in ground is a one-foot stromatolitic layer with many orthocone cephalopods. Pitcher called this his Assemblage C and assumed it was laid down as a blanket during a relative drop in sea level. It forms a dip slope through which appear, apparently, the tops of Assemblage B mounds, as well as small mounds of Batostoma chazyensis alone which Pitcher called Assemblage D. At the west end of this cuesta-like feature, nearest the main road, a good cross section of an Assemblage B mound is exposed (see Plate 2).
Down the dip slope, above a ten-foot interval of grey calcarenites, are mounds in the lower part of the Valcour Formation. They are composed of Batostoma campensis, together with the alga Solenopora. Some Zittelella may be found. The bryozoa are clearly dominant.
Walk northeastward along strike for about a half-mile, observing Crown Point mounds as you go. You will eventually reach the Goodsell Quarry, operated by the Vermont Marble Company. The quarry is opened in the lower beds of the Crown Point which are relatively lacking in reefs except for small stromatoporoid-algae mounds. The quarry has been intermittently active, and the stone, which makes a beautiful black marble when polished, has been widely used as an interior trim. The rock weathers light gray, and has also been used locally as a dimension stone. It was used to build the old border fort, Fort Montgomery, visible from the Rouses Point bridge.
CAREFULLY avoiding falling into the water-filled quarry, one may observe vertical sections through stromatoporoid-algal mounds and their relationships with the surrounding calcarenite (see Plate 5). By tracing laminae from the mounds into the surrounding sediment, one can see that the mounds never stood more than a foot or two above the sea floor at anyone time, though the total thickness is much greater because of the persistence of the mound population on the same spot. On the quarry benches, especially the glacially polished upper surface, one may see plan views of mounds and note their tendency to a N-S lineation. On these surfaces also, especially when wet down, one may see orthocone and other nautiloid shells, and Maclurites shells, overgrown by algal coatings.
This ends our examination of the Isle La Motte exposures. On our way back we will stop at the Sheldon Lane section, south of Chazy, where we may collect from the Crown Point and lower Valcour, in essentially the same facies.
The Sheldon Lane beds dip north. We will begin with cross-bedded upper Day Point (Fleury) calcarenite at the south end and walk through the entire Crown Point section including reef mounds with the same fauna as in LaBombard's pasture. North of the road is an old quarry in which the lower Valcour is well exposed.

STOP 2. Sheldon Lane
On our way back we will stop at the Sheldon Lane section, south of Chazy, where we may collect from the Crown Point and lower Valcour, in essentially the same facies.
The Sheldon Lane beds dip north. We will begin with cross-bedded upper Day Point (Fleury) calcarenite at the south end and walk through the entire Crown Point section including reef mounds with the same fauna as in LaBombard's pasture. North of the road is an old quarry in which the lower Valcour is well exposed.

G. SURFICIAL GEOLOGY AND GEOMORPHOLOGY OF WHITEFACE MOUNTAIN AND KEENE VALLEY
Jesse L. Craft
Carleton University
Ottawa, Ontario

STOP 1. Whiteface Mtn "Coon Pit" stop
Proceed from the bus to the chair lift and ride to the end of first lift. "Coon Pit" stop. After getting off the chair lift walk up stream to the waterfall. There is a deep glacial grove enlarging a joint. Which direction was the ice flowing to cut this grove?

STOP 2 - Top of Whiteface Mountain
After leaving the chair lift walk to the top of the mountain. Gather at the elevation marker.
From this point you can observe the only indication I have observed of continental glaciation over riding the mountain tops in the high peaks region. This is the "roches moutonnees" form of the crest on the south side of the peak.
Observe the "horn" configuration of the peak area. The "cirque form" of the valleys leading away from the peak and the very narrow "arete" ridge to the west of the peak. Could these features develop from Continental Glaciation?

STOP 3 - Atmospheric Sciences Research Centre, Whiteface Mountain Field Station
Leave the bus and walk up the jeep road to the Whitebrook valley trail (unmarked). We will be going about ~ mile up the valley. Anyone that wishes to, may stay at the centre and look around the lodge.
Whitebrook Valley Moraine. This ridge was described by Alling (1919) as a lateral moraine of a local glacier occupying this "cirque". Notice the high percentage of Potsdam sandstone pebbles lying on the surface.

STOP 4. - County Gravel Pit on 9 N
10' till, grey oxidize moderately stoney, very sandy at base, large folds of underlying sand, silt and clay carried upward into till.
50 to 100' fine sand, silt and clay upper 5' strongly contorted by load folding.

H: META-ANORTHOSITE OF THE JAY-WHITEFACE NAPPE, AUSABLE FORKS-LAKE PLACID QUADRANGLES, NORTHEASTERN ADIRONDACKS, NEW YORK
Bradford. B. VanDiver
State University of New York
Potsdam, New York

STOP 1. Locality A, Jay, Ausable Forks Quadrangle
Take woods road beginning opposite Tirolerland restaurant, 0.8 miles N. of Jay on Route 9N. Follow woods road to point where it begins to veer sharply south, 0.25 miles from Route 9N. Climb 100 yards south to exposed slabs on hilltop which has been stripped and cleared by Rock of Ages Corp. Professor Brewster Baldwin of Middlebury College prepared base map by plane-tabling on which geology and sample localities have been plotted (Fig. 2).
The exposure is representative of massive, generally porphyroelastic, core meta-anorthosite of the "Marcy-type," but shows the considerable local compositional and textural variation encountered in this map-unit. Three local facies have been distinguished here, viz:
Facies I: A fine-to-medium grained granoblastic equigranular gabbroic meta-anorthosite, locally passing into an anorthositic metagabbro, largely confined to the northwestern portion of the outcrop. It shows many analogies with the border facies anorthosite. (Whiteface- type") and perhaps should be so mapped. Clinoopyroxene (Wo40En35Fs25) takes place of hypersthene in this facies, and garnet is absent.
Facies II: This is the predominant lithic type in the exposure and consists of inequigranular meta-anorthosite with plagioclase megacrysts forming from about 25 to 70 per cent of the total rock volume, the proportion of megacrysts decreasing toward the southeast. Hypersthene is the major ferromagnesian constituent, but locally incipient rims of garnet and clinopyroxene are visible. Before concluding that the finer-grained plagioclase matrix between the megacrysts is of proto clastic origin or produced by post-crystallization deformation, examine the hypersthene grains intergrown with the matrix. Many will be seen to be optically continuous as shown by reflections from parallel cleavage surfaces and may indicate an ophitic intergrawth suggestive of a final, possibly eutectk, assemblage.
Facies III: Appearing as irregular patches up to 50 feet across in facies II meta-anorthosite is a pegmatitic phase, varying from meta-anorthosite to anorthositic metanorite. A coarse ophitic intergrowth of little-granulated plagioclase crystals and hypersthene, both attaining lengths up to one foot, is characteristic of facies. Garnet rims may be seen around some of the hypersthene.
In Table 2 are given modes measured on the outcrop (numbers painted on outcrop and located on Fig. 2) covering 6.5 feet2 apiece (619 cm2 ) with reticular spacing of one inch (2.54 cm.) Means for each of the facies and a mean for all modes, which have been apportioned among the various facies proportional to their aerial extent, have been calculated. The anorthite content of a limited number of plagioclase samples, both megacrysts and the finer grained matrix, has been determined by refractive indices. The compositional range is from calcic andesine (An44) to sodic bytownite (An72) with the average of all determinations An53. Where both matrix and megacrysts were measured in a single sample, the composition was identical in each. It is likely, however, that many of the megacrysts show chatoyant core and a non-chatoyant rim.

STOP 2. -- Omitted --

STOP 3. Roadcut South of the Flume, Route 86
In this extensive exposure (for cross-section 835 feet long prepared from a photomosaic refer to Plate 3), the relationships between three distinctive anorthositic varieties are well displayed. Coarse-grained porphyroclastic meta-anorthosite to noritic meta-anorthosite (Facies 1) with blue-black plagioclase megacrysts composing from iO- 40% of the total rock flanked by a medium-grained, generally equigranular noritic meta-anorthosite to anorthositic meta-norite gneiss (Facies II) and a medium-grained, granoblastic anorthosite with mottled pale green and pink to lavender plagioclase (Facies III). For petrographic details, see Table 3. Despite the considerable compositional and textural variation, the anorthosite content of plagioclase remains remarkably constant {ca. An55) with the principle difference being the Fe-Ti oxide inclusions of the dark plagioclase megacrysts and the absence of impurities and characteristic coloration of the (recrystallized?) plagioclase of Facies III.
Facies I meta-anorthosite closely resembles massive core meta-anorthosite of the Marcy-type although here it appears to be isolated from any extensive exposed body of such meta-anorthosite. Facies II is most closely related to border facies (Whiteface-type) meta-anorthosite and Facies III which forms most of the gorge (Flume) along the Ausable River just to the north is found interlayered with noritic meta-anorthosite at numerous localities in the Whiteface sheet to the west.
The meta-anorthosite facies are numbered in the order of their presumed relative ages as shown at this exposure. Block structure with inclusions of Facies II noritic meta-anorthosite gneiss in the much more leucocratic Facies III is especially well developed 600 feet south of the northern end of the cut. The position of Facies I meta-anorthosite in the sequence is much less certain, and it is placed first largely because of the inclusion within Facies II near the 400 feet marker. Large masses of Facies II, however, are surrounded by Facies I between the 200 and 300 feet markers. There is thus some evidence of reciprocal intrusion if geometric factors are ignored. Another example is patches of Facies III meta-anorthosite surrounded by Facies II at 400 feet. Some discussion of field criteria for age relationships will undoubtedly be warranted. In general elsewhere in the eastern Adirondacks as described in the literature, it is more common to find gabbroic meta anorthosite intruding and enveloping blocks of a more leucocratic meta-anorthosite. At the next stop we shall examine further evidence bearing upon the anorthosite sequence.
There are small inclusions of diopsidic or garnet-biotite rich fieldspathic gneisses or granofelses in Facies III meta-anorthosite at 690 feet (specimen 66-56). More extensive layers of diopsidic metasediments in Facies II gabbroic meta-anorthosite are to be found 100 yards west of the bridge over the Flume just to the north.
The outcrop shows a number of fine-grained diabase dikes from 10 inches to 6 feet thick nearly parallel to the general trend of the cut (estimated mode, samples 62-70, Table 3).
Many shear surfaces of indeterminate displacement are present, the most prominent set perhaps being about N30E, parallel to the cut face and on strike with the pronounced linear through Wilmington Notch visible to the south, a locus of probably major faulting. Augen gneiss zones in the meta-anorthosite with considerable microclinization may be seen at 100 feet and at 320 feet (estimated mode, sample 62-72, Table 3). Garnet in the meta-anorthosite appears to be localized in these gneiss zones, a phenomenon observed at many other exposures. Many secondary minerals occur along the late shear surfaces, including calcite, quartz, epidote, and chlorite. Natrolite has also been identified.

STOP 4. Stream-worn slabs under lower ski lift, elev. 1800 - 2000 feet
Between powerhouse and mid-lift station.
Drive into Whiteface Ski Center from Route 86 between Wilmington and Lake Placid. The lift will probably not be operating, so climb ski trail 600 feet vertically right (north) of stream along lift line to bare stream slabs above powerhouse.
Three distinct facies of the meta-anorthosite series are represented at this exposure, two of them related to those seen at the Flume. The earliest member of the series (Facies 1) is not, and is preserved as several rounded inclusions mostly under running water in the stream bed as it veers north of the lift line towards the upper end of the exposure. It is a fine-to-medium-grained equigranular mafic anorthositic meta-gabbro enclosed by both Facies II and Facies III rocks. For thin-section mode see specimen 65-175 in Table 5. Notable is the calcic content of the plagioclase (An70) compared to that of Facies II (An52-55)'
Facies II comprises most of the outcrop. For thin-section modes, see Table 5,: for larger-area point counts with the screen employed at Stop 1, see Table 4 -- the numbers are painted on the outcrop. The average rock is a noritic-meta-anorthosite (color index 17.85) with mean per cent plagioclase megacrysts 24.25 and plagioclase matrix 57.80. The proportion of megacrysts varies from a minimum of 7.6% to a maximum of 42%. There is also considerable textural variation with a medium-grained rock showing subtle compositional banding and a suggestion of sub-ophitic texture in the matrix the preponderant type (modes, no. 1-10). Mineralogically similar, but coarser-grained and showing better developed ophitic texture is mode no. 11, whereas modes no. 13 and 14 are somewhat more leucocratic than the average but otherwise related texturally.
Facies III is an inequigranular mediumn-to-coarse-grained leuocratic meta-anorthosite apparently cutting Facies II noritic meta-anorthosite in irregular dikes with apophyses. It is interpreted as definitely younger than Facies II, and bears out the sequence deduced at the Flume. Similar dike-like bodies of Facies III in Facies II meta-anorthosite are present in slabs along the Boreen ski trail 100 feet higher to the northwest, and may be visited if time permits.
It is worthwhile inspecting some of the coarser-grained ophitic Facies II noritic meta-anorthosites in the lower narrow portion of the stream slabs for textural evidence of protoclasis or several stages of granulation followed by crystallization. Representative of the textures seen are large, partially granulated, plagioclase megacrysts with inserted ungranulated hypersthene crystals and shattered plagioclase augen veined ty noritic meta-anorthosite. Relationships may be explained by varying paths of crystallization in Di-Ab-An ternary coupled with one or more stages of cataclasis. Locally there appear to be eutectic intergrowths of plagioclase and hypersthene between plagioclase megacrysts.
Observations bearing upon the metamorphic history of the metaanorthosite at this locality are the following:
1. Garnet is generally absent except along shears. At the slabs in the Boreen ski trail a little higher, leucocratic meta-anorthosite "dikes" in gabbroic meta-anorthosite have garnet and clinopyroxene + hornblende rims to hypersthene grains whereas hypersthene does not have such reaction rims in the gabbroic meta-anorthosite.
2. Hypersthene generally is rimmed by clinopyroxene or horrnblende or an intergrowth of the two in the noritic meta-anorthosite under the lift. Locally, a hypersthene core is rimmed by clinopyroxene and this in turn by hornblende. It is possible that the clinopyroxene rim represents exsolution from a primary orthopyroxene or inverted pigeonite host. No exsolution lamellae have, however, yet been detected in the hypersthene. If the clinopyroxene is a result of unmixing, then the only metamorphic mineral here is hornblende.

STOP 5 (6, 7 ...) Whiteface Memorial Highway and summit
If time permits, we will ride up the Whiteface Memorial Highway, making one or more stops, and take one of the trails to the summit, preferably the northeast ridge trail from the "Wilmington turn" at the large cut below the main parking lot.
The meta-anorthosite rocks exposed in the Whiteface sheet extending from the upper slopes of Whiteface Mt. on the south to Catamount Mt. on the north and the Franklin Falls area on the west show many mineralogical, textural, and structural contrasts with the border facies of the meta-anorthosite we have thus far examined.
In general, they are much more recrystallized and relict igneous textures as observed under the ski lift at Stop 4 are rare. Foliation, and often lineation as well, is strongly developed and plagioclase megacrysts, mostly small and augen-shaped, seldom constitute more than a few per cent of the total rock. Banding is also common; and gabbroic meta-anorthosite alternates with leucocratic meta-anorthosite layers over short intervals. Garnet becomes a major phase and hypersthene a correspondingly less important constituent. There are layers of varying thickness from less than an inch to many tens of feet of mangeritic rocks, of Keene gneiss and of metasediments including coarse-grained gray quartzite and garnet-diopside granofels. Graphite is present locally near marble or calc-silicate contacts. I believe many of the physical and mineralogical characteristics of the Whiteface meta-anorthosite sheet can be explained by its tectonic position at the leading edge and base of the nappe described in the introduction to these notes.
Table 6 presents 20 modes of anorthosite rocks on Whiteface Mt. along the Memorial Highway and summit ridges in order of increasing elevation to emphasize any depth-controlled trends that may be present in the sheet. As we climb the northern slope of the Whiteface massif we are slowly passing upward through a nearly dipslope compositional layering parallel to a regional foliation.
At the Lake Placid turn (First switchback) there is a spectacular view of Lake Placid to the south. The contact between gabbroic meta-anorthosite, here somewhat more mafic than average, and mangeritic rocks is exposed just to the east of the turn. At the contact the mangerites are greenish but further away they become progressively pinker and quartz content increases. Boudins of anorthosite are enclosed in the mangerite-charnockite sequence -- is this an intrusive or tectonic relationship?
At the Wilmington turn, gabbroic meta-anorthosite structurally overlies green mangerite at the eastern end of the large cut. Meta-anorthosite blocks in the retaining wall excavated from the cut provide a good sample of the average rock in the cut. Garnet coronas are fairly common. On the upper, slightly weathered surfaces of the cut strong gently northeast-plunging lineation shown by aligned mafic minerals is shown to advantage. There are also thin quartzitic beds parallel to the foliation in the meta-anorthosite. One meta-anorthosite block not quite in place shows sharp folding of a quartzite layer.
Continuing up the trail along the northeast ridge of Whiteface Mt. to the summit, the open slabs will show the strongly gneissic, lineated, and banded character of the gabbroic meta-anorthosite. Thin plate-like quartzite layers parallel to foliation are common. From the summit, if you descend the south face 100 vertical feet you will cross the meta-anorthosite-mangerite contact once more. There is no intermediate andesine augen mesoperthite gneiss (Keene gneiss) at the boundary. Quartz content varies widely from 30-40 per cent to less than 5% in adjacent layers.
If the day is fine, it will be possible to point out regional relationships between anorthosite and related rocks in the High Peaks to the south and in the Jay-Whiteface sheet to the southeast and northwest.

J: SURFICIAL GEOLOGY OF THE INTERNATIONAL LEAD COMPANY MCINTYRE DEVELOPMENT AT TAHAWAS, N.Y.
Jesse L. Craft
Carleton University
Ottawa, Ontario

J: SURFICIAL GEOLOGY OF THE INTERNATIONAL LEAD COMPANY MCINTYRE DEVELOPMENT AT TAHAWAS, N.Y.

STOP 1. Deltaic sands, forset beds dipping west into valley wall
Deltaic sands, forset beds dipping west into valley wall. Delta built into Glacial Lake Warrensburg (Miller 1925).
Water seems to have carried material into the Valley from the Blue Ridge moraine which lies about 3 miles due west.

STOP 2 - Blue Ridge Moraine
This is a narrow moraine complex blocking off the east west valley. Outwash from this moraine can be traced into the deltaic deposits of the last stop. The north side has been modified by water flow from the north indicating ice occupying the valley to the W of this spot with the main N-S valleys free of ice.

STOP 3 - Outwash gravel and Kame deposits
Water was flowing out of Niagara Brook along the north side of the Blue Ridge Moraine into Glacial Lake Warrensburg.

STOP 4. Striated bed rock face
Striated bed rock face on Highway 128, 2 miles west of Newcomb. Just west of BM 1595 and Lodo Pond.
Which way was the ice flowing past this point?

STOP 5 - Tahawus, McIntyre Development, International Lead Co.
Excavation of the present pit area was started in 1961. In clearing the overburden from the area formerly under Sanford Lake, a multiple till section was exposed with interglacial lake sediments between two tills. Disseminated wood fragments including material identified as Pinus strobus (David Bierhorst, Dept. of Botany, Cornell Univ.) were collected by E. Muller and the section was described (Muller 1966). The wood fragments were dated at an age greater the 40,000 years (W-1520). Muller describes two tills separated by the interglacial lake deposits.
This author observed what appeared to be a third till when visiting the pit in 1966. Detailed measurement in the pit verified the existence of three till units separated by stratified sediments.
Section at Sanford Pit (as exposed in 1966)
Top
| Feet
Coarse sand and gravel, oxidized in zones - upper part mixed with excavation fill from Tahawas village | 2 - 5
Laminated sand, silt some gravel lenses, upper parts oxidized, well developed ripple marks cut and fill structures throughout, bedding dips 8°N. | 1 - 20
Till,yellow brown oxidized moderately stoney, non-calcareous very few ore pebbles. | 1 - 25
Sandy gravel, laminated sand and silt. Numerous small folds overturned to the north. In some places this layer has been so disturbed it becomes till like in texture. | 4
Till, gray, moderately stoney, non-calcareous few Potsdam pebbles observed, no ore pebbles. Contact with overlying sediments marked by thin silt bands. | 8 - 15
Sand, yellow brown oxidized medium to coarse changes to sandy gravel a short distance to the west. | 5 - 15
Contact with underlying laminated clay not observed. |
Clay, brown with few pebbles and disseminated wood fragments including material identified as Pinus strobus (David Bierhorst, Dept of Botany, Cornell Univ.) Age greater than 40,000 years (W-1520). | 3 - 12
Gravel stratified | 1
Till yellow grey moderately stoney, noncalcareous, oxidized | 5
Till, stoney, numerous ore pebbles folded silt, sand inclusion, shear planes dipping south | 1 - 30