NYSGA 1973
NYSGA
NEW YORK STATE GEOLOGICAL ASSOCIATION GUIDEBOOK
S.U.N.Y. BROCKPORT and MONROE COMMUNITY COLLEGE
Guidebook to Field Trips
45th Annual Meeting -September 28-30, 1973
Rochester, N.Y. Area
Co-hosts: State University of New York College at Brockport, Monroe Community College
Edited by: Philip C. Hewitt, Department of, The Earth Sciences, SUNY Brockport
Field Trip Leaders Robert W. Adams, Department of The Earth Sciences, SUNY Brockport Hilliam A. Bassett, Department of Geological Sciences, University of Rochester Samuel J. Ciurca, Jr., Eastman Kodak, Rochester, N.Y. Thomas X. Grasso, Department of Geosciences, Monroe Community College Gary L. Kinsland, Department of Geological Sciences, University of Rochester William Kirchgasser, Department of Geological Sciences, SUl-.,JY Potsdam Wendell D. Rhodes, Department of Anthropology, SUNY Geneseo Robert A. Sanders, Department of Geosciences, Monroe Community College Victor E. Schmidt, Department of The Earth Sciences, SUNY Brockport Richard A. Young, Department of Geological Sciences, SUNY Geneseo
PREFACE
In preparing this guidebook the basic premises accepted were that simplicity was to be primary and maximum flexibility of style and opinion would be maintained.
Therefore, the editor made no attempt to alter any author's style or opinion. In this way, of course, the editor's task became easier. All that remained was to do the usual proofing, make minor changes and prepare the parts as a whole. Even this task was simple since each field trip is a whole unit and the guidebook merely a collection of field trip descriptions.
If the trips and the meeting are successful it is because of the efforts of many people; the contributors, my patient faculty and students, my secretary and many others including Mrs. Marion Cassie who designed the cover. My thanks go to them and most particularly to Thomas X. Grasso of Monroe Community College who is my co-host.
We hope you will enjoy the trips and the many different styles in this book.
Philip C. Hewitt Editor
INTRODUCTION
The geology of the Rochester area involves some intriguing problems. These are primarily based in the fields of paleontology and stratigraphy, glacial geology and geomorphology, mineralogy and other related subfields. A simple way to describe the geology as a whole is that it involves Lower Paleozoic (Ordovician to Devonian) sedimentary rocks veneered by dissected glacial deposits.
Although a few minor folds appear and the area displays a small number of faults, this is not the easiest place in which to observe structural geologic features. Nor will one find igneous or metamorphic rocks in place here. Rather they can only be seen as erratics from glacial deposition. It is obvious therefore, that the field trips selected for our area involve the type of geology which is so plentiful and well exposed here.
The emphasis for each trip is to teach. The method or style used by the field trip leaders may differ but the intent is the same. In every case the student is the person for whom the trips were planned and for whom the papers were written. The only assumption that is made is that the student has had at least a few courses in geology and will be able to follow the basic concepts involved.
The oldest rocks exposed in this area are of the late Ordovician and are found in the "Rochester Gorge" of the Genesee River Valley. Most of the rocks exposed at the surface in the northern part of the area (south of Lake Ontario) are Silurian in age. Knowing that the strata dip generally to the south it is obvious that younger strata will appear in the southern part of the region. Therefore, Devonian beds are exposed south of Rochester. Erosion by streams and ice and subsequent deposition by glacial action represent the most obvious later events following post-Paleozoic uplift. Yet weathering and erosion continue to leave their mark - erosion by humans shows strongly.
All field trips have been designed to add to the brief outline above. The mineralogic visit to the Penfield Quarry is placed in context with the stratigraphy and general geology of the Rochester area. At Hamlin Beach recent sedimentation will be observed - though no precise details can be given in this guidebook for that locality. Recent water levels and strong wave action have altered the entire picture there. No one can predict what conditions will be like at the time of the trip. We shall have to wait and see.

A: GLACIAL GEOLOGY OF THE WESTERN FINGER LAKES REGION
Victor E. Schmidt
State University College at Brockport
Note: This trip and discussion are designed primarily for undergraduate students, rather than for specialists in glacial geology -- who are, nonetheless, most welcome.
An attempt, however imperfect, is made to distinguish observations from inferences, hypotheses, and speculations based on these and other observations.
The number of proposed stops is probably greater than time will allow, and so selection will be made on the basis of weather conditions and the interests of the group.

A: GLACIAL GEOLOGY OF THE WESTERN FINGER LAKES REGION

Honeoye Creek
At Rush, Rt 15A crosses westward-flowing Honeoye Creek, carrying water from three of the western Finger Lakes to the Genesee River, which flows northward to Lake Ontario.

Glacial drainage channel
At Sibleyville, 1.3 mi from Rush, the route crosses a broad, swampy, flat-bottomed valley, interpreted as a glacial drainage channel which carried a river of glacial meltwater eastward, along the front of the glacier. (If time permits, a slight detour via Phelps Rd and Wagner Rd will allow a better view.)

Middle Devonian Onondaga limestone
Directly west of Honeoye Falls, 3.6 mi from Rush, is an outcrop of Middle Devonian Onondaga limestone, the formation over which Honeoye Creek falls at Honeoye Falls.

Drumlins
Long, streamlined hills - typical drumlins - parallel the route; the road goes over several, and a large one can be seen to the west, from approx 4 mi south of Lima.

Drumlins
Road crosses a field of drumlins, many of them wooded, at about 1200 ft.

STOP 1. Rt 20A between Hemlock and Honeoye
Rt 20A between Hemlock and Honeoye, 2.5 mi east of jct with Rt 15A. (Bus to let group off on left side of road, opposite bedrock exposure; then to wait on left side of road beyond
road cut ahead.)
Bedrock exposure: Shale of the Sonyea Group, Upper Devonian. Note bedding, joints, and concretions. Are there any fossils?
Questions: How resistant is this shale to weathering? How resistant would it have been to glacial abrasion; to glacial plucking?
Road cut: Cut in the south end of a drumlin. An unsorted mixture of rock material, from clay-size to boulders. Much dark gray shale and clay. Many exotic rocks. Many stones show scratches.
Exotic stones: (Possibly groups determine percentages)
Composition -crystallines__: red sandstones__: limestones and dolomites ___: others ___%
Shape - well rounded___: subrounded subangular___: angular___%
With scratches ___%
What is the fabric of this material, if any? (Possible demonstration. )
Inferences: The material is lodgment till which includes much ground-up and broken-up "local" shale. This till was deposited beneath an actively moving glacier. Well rounded, yet scratched, pebbles represent glacially transported and abraded streambed or lakeshore gravel.
The drumlins were formed by the "plastering" of till on bedrock. Their streamlining is a result of shaping by delicate adjustment of deposition and erosion (re-erosion?) to such conditions as load, velocity, pressure, and temperature of the bottom ice.

Honeoye Lake, delta
Honeoye Lake, one of the smallest Finger Lakes, drains northward into the Genesee River, Deltas show on both sides of the lake; the largest, California Point, on this side, has a trailer "park".
How does the spacing of the cottages appeal to you?

STOP 2. West Lake Rd, 4.6 mi south of Honeoye.
View:
South end of Honeoye Lake. Steep valley sides; no roads descend the slopes here. Small streams in steep gullies marked by dark conifers. One of these streams goes under the road, nearby.
Briggs Gully, a bedrock gorge directly acyoss the lake, descends 700 ft in approx 2 mi. At its lower end is a gently sloping area, underlain by gravel, which extends into the lake.
South of here, Honeoye Valley shows an interesting cross-profile which makes a sharp break with the upland surface on either side. Is this cross-profile a catenary curve? How does one tell?
Compact lodgment till is exposed in the bed of the small gully nearby. Exotic boulders of augen gneiss, anorthosite, etc.
Inferences:
Honeoye Valley was originally a preglacial stream valley, later deepened and steepened as a result of glaciation. It was affected by glacial abrasion, plucking or quarrying, and possibly also by frost wedging beneath the glacier and ahead of it. In addition, there probably was considerable erosion by meltwater. Undoubtedly the valley was subjected to, not a single glaciation, but repeated glaciations - both advances and retreats.
The small streams which flow down the steep slopes are consequent streams. They developed in consequence of a "new" land surface that resulted from glacial erosion of the preglacial valley. Hence these streams are postglacial consequents.
Briggs Gully was formed as a result of a great increase in the erosive ability of the creek in descending from an upland valley, at nearly the preglacial level, to the level of the present lake. It joins a hanging valley, at about 1700 ft., with the glacial trough of Honeoye Valley. Hence the gully is postglacial, or interglacial, or a combination of both. Material excavated from the gully has been, and is being, deposited in a combination alluvial fan and delta at the base. This adjoins the delta at the head of the lake.

Glacial trough and the postglacial consequents
The steep slopes of the glacial trough and the postglacial consequents show well. The rock slides may be due to cutting timber.

Hunt Hollow
At Hunt Hollow note the knobby hills, and the flat-floored, swampy channel, containing ponds, in the valley bottom

STOP 3. West Lake Rd, 12.7 mi south of Honeoye
Road cut and hillside:
Gravel and sorted sand. Many pebbles, especially exotics, are well rounded. Many are scratched, including some that are well rounded. Are there any indications of the direction of water flow?
Knobby hills, with "dimples", similar to the hilly topography in Honeoye Valley between Hunt Hollow and here.
The hilltop affords an overlook of the flat-floored, swampy channel noted previously along the road northwest of here. This channel curves around the far side of the wooded hill ahead (SSW). The topographic map (Naples, 7.5') shows the relationship clearly. Almost the same situation occurs about 0.5 mi to the east.
In the distance are high bedrock hills: Hatch Hill (ESE), above Naples, at 1800+ ft; Knapp Hill (SE) at 2040+ ft; Pine Hill (S) at 2040+ ft; unnamed hill (SSW) above Atlanta, at 2012 ft. Valleys between these hills include: Canandaigua Valley, south end between here and Hatch Hill; Cohocton Valley, north end between Pine Hill and the hill above Atlanta; North Cohocton-Dansville Valley, east end this side of the hill above Atlanta.
At the junction of these valleys is a large area of knobby topography. Much higher and nearer is a flat-topped gravel terrace.
Inferences:
The material in the road cut is morainic. Much of it, at least, was deposited by meltwater, possibly in standing water of an icemargin or preglacial lake. The knobs and "dimples" on the hillside represent a constructional slope of the moraine.
The flat-floored channel is the spillway of a proglacial lake, at 1140+ ft, in the Honeoye Valley. The wooded hill ahead is a "run-around hill"; or umlaufberg -probably a knob of bedrock isolated by the proglacial lake overflow when its former course was blocked on this side by ice or morainic material.

Naples Tree: lycopod or club moss
West of Naples, at the mouth of Grimes Gully, D.D.Luther found the "Naples Tree" in 1882. This is the "trunk" of a lycopod or club moss, 16t ft long, of Upper Devonian age, now on display in the New York State Museum in Albany.

STOP 4. Bristol Springs Road (County Rd 12) 2 mi north-northeast of Naples
Overlook: (at vineyard of Mr. David Gentner)
South end of Canandaigua Lake, with Parish Flat and West River Valley. West River, flowing from the northeast, makes a barbed junction with northward-draining Canandaigua Valley.
Small postglacial consequent streams descend the steep sides of the valleys in small ravines, marked by dark conifers.
Parish, or Conklin, Gully (SE) is a bedrock gorge, with a gravel pit near its base. The gorge ends at a broad, semicircular area of gently and uniformly sloping farmland.
Inferences and comments:
The barbed junction of West River Valley and Canandaigua Valley supports the concept of ancient south-flowing consequent drainage of this region, later reversed as a result of stream capture or the blockage of valleys by glacial deposits. Fairchild inferred that, during Tertiary times, the Canandaigua Valley drained into the west-flowing Dansville River; at the present site of Sonyea this joined the obsequent, north-flowing Genesee River, and then continued northward to the subsequent Ontarian River (1926, p. 224 and Plate 84).
Parish Flat is a modern delta deposited at the head of Canandaigua Lake. The gentle slope at the base of Conklin Gully is on an alluvial fan. The gravel being excavated near the base of Conklin Gully may be part of a delta built by this stream into a proglacial lake that occupied the valley to this height when drainage to the north was blocked by glacial ice. More likely, it is in a kame terrace built between stagnant ice in the valley and the bedrock side of the valley. There is a bench partway up the valley side along Conklin Gully, but its cause is not known. It may be due to resistant bedrock, or possibly is a higher delta or kame terrace.
Note the attempts by man to "improve" Canandaigua Lake and its environs by bulldozing shale from the slope into the lake, allowing more cottages to be built. Fortunately, this endeavor seems to have been stopped by New York State. But others continue!

STOP 5. (Lunch stop) Ontario County Park.
Road from Bristol Springs ascends the west side of Canandaigua Valley. Shale and sandstone of the West Falls Group, Upper Devonian, are exposed, as well as considerable glacial drift.
View eastward:
Appalachian Plateau, dissected by deep valleys. Sub-accordant summit level at approx. 1900-2000 ft.
Highest hill (NNE) is Stid Hill, 2080+ ft. Moderately sharp hill (ENE) is Bare Hill, 1540+ ft, with Canandaigua Valley on this side of it and Vine Valley to the right and beyond it. Like West River Valley, Vine Valley also makes a barbed junction with Canandaigua Valley.
Inferences and question:
The sub-accordant summit level is an erosion surface, considered by Cole to have been reduced below the Upland Peneplain (1938, pp. 194, 196; 1941, p. 148). The main valleys below this surface were deepened by preglacial streams as a result of rejuvenation, and later deepened further by glacial erosion. Is this view valid?
The "Jump-off":
Overlook, at approx 2100 ft, of Berby Hollow, approx 1300-1400 ft at the bottom. This valley contrasts sharply with the upland surface. Its cross-profile approaches a catenary curve.
Berby Hollow contains no major drainage - only small creeks. Divide area is in the middle distance. Hummocky hills of gravel on the valley floor; some of these have been destroyed.
Question and inferences:
How much of the shape of Berby Hollow is due to preglacial rejuvenation and stream incisement, and how much to glacial erosion?
Gravel hills on the valley floor are ablation deposits let down by the last remnants of glacial ice, probably stagnant.
Exotics in the till here include red sandstone of the Grimsby (Medina), and possibly Queenston, formations. These formations outcrop in a belt passing through Rochester and along the south shore of Lake Ontario, below approx 400 ft. The presence of their fragments here indicates that the ice sheet covering the site of Rochester must have reached a thickness of at least 1700 ft, about 4 times as high as the Xerox Tower in Rochester.

STOP 6. Rt 21, 2 mi southwest of Naples.
Road cut and vantage point:
Unsorted mixture of clay-size to cobble-size material. Many exotic rocks. Limestones, especially, show scratches. Calcareous nodules (concretions?) also occur in the material. The stones consist of - crystallines____: red sandstones____:
carbonates____: local gray siltstones and sandstones ____%
Approx____% show scratches.
Hummocky topography, with many hollows, covers a large area between bedrock hills, at the junction of the major valleys.
Three terraces visible in distance: largest, wooded (E of N) at 1100-1120 ft; smallest (N) at 1200 ft; highest (NNW) at 1340 ft;
Inferences and questions:
Material in road cut is till, possibly containing much scraped-up proglacial lake clay. Hummocky topography marks an end moraine, probably correlative with similar moraines at the heads of other Finger Lakes valleys, named the Valley Heads Moraine by Fairchild (1926, p. 226 and Plate 88). This moraine was deposited during a several-hundred-year time of balance between forward movement and the backward melting of the ice, during the last general recession. C-14 dates indicate this may have taken place as recently as 12000 years BP. (What are the most recent data?)
What is the origin of the calcareous nodules? How old are they?
The terraces are possibly high-level deltas deposited in three different levels of proglacial lakes occupying this valley while drainage toward the north was blocked by ice. If so, one or more of them may have been deposited by outflow from a proglacial lake in Honeoye Valley. However, these terraces may instead be kame terraces, deposited between stagnant ice and the valley side, possibly ice-margin deltas built by meltwater streams.

Proceed westward and southwestward across the Valley Heads Moraine
Note morainic topography, including kettles. A flat-bottomed channel runs southwestward along the west side of the valley. Fairchild identifies this as the spillway over the moraine of Lake Naples, a proglacial lake in the south end of the Canandaigua Valley (1895, p. 362), presumably post-Valley Heads in age.

North Cohocton-Dansville Valley
Immediately south of the moraine, the route crosses the North Cohocton-Dansville Valley, floored by gravel, probably outwash.

STOP 7. Black Creek Rd, 0.4 mi S of Sawdust Rd (County Rd 36).
Blackcrick Hollow:
Steep-walled north-south gorge. Flat, swampy floor south of the divide at 1460+ ft. Bedrock exposed in walls. Alluvial fans at the base of tributary streams.
Inferences and questions:
This is a marginal drainage channel or glacial lake spillway (How does one tell the difference?), formed by meltwater erosion of a preglacial valley or col. (How much lowering of the preglacial divide is indicated? Can this be estimated from the map?)
If this channel is the former spillway of a proglacial or icemargin lake, presumably in the North Cohocton-Dansville Valley, at 1460+ ft, what kept the lake from escaping through the southward-draining Cohocton Valley? Possibilities include:
a) Stagnant ice blocking the Cohocton Valley at, or south of, North Cohocton and Atlanta.
b) The end of a lobe of ice, possibly the Canandaigua lobe at North Cohocton, or the Keuka lobe at Bath, blocking the Cohocton Valley during or before Valley Heads time.
c) Valley Heads or "advance" Valley Heads end moraine, or even earlier end moraine (Arkport or Almond?), blocking the Cohocton Valley south of North Cohocton.
Is it just happenstance that a pitted gravel terrace (kame terrace or delta?) on the north side of the North Cohocton-Dansville Valley, nearly opposite Blackcrick Hollow, attains the same elevation (1460+ ft) as the divide in Blackcrick Hollow?

Blackcrick Hollow drainage channel
The Blackcrick Hollow drainage channel or spillway seems to lead toward a series of gravel terraces on the west side of the Cohocton Valley, north, west, and especially south of Cohocton. Some of these attain elevations of 1480+ ft and possibly more.
What is the nature of these terraces? Are they deltas, kame terraces, outwash, or what? Why are there several levels? What caused the concavely curved bank at one level, visible from Loon Lake Rd, Rt 371, just west of Cohocton? Later, if time permits, these features will be seen and discussed.

STOP 8 East side of Rt 371
Terrace and gravel pit: (on property of Mr. Myron Crouch)
Somewhat sorted and stratified "bright" gravel and sand. A great variety of exotic rocks. Pebbles mostly well rounded. Well rounded boulders of resistant crystalline rocks; poorly rounded blocks of local sandstone. Many "ghost" pebbles of weathered carbonates, including cherty Onondaga limestone.
The pebbles consist of --crystallines___: red sandstones___: carbonates___: local gray siltstones and sandstones___%
They are --well rounded___: subrounded subangular___: angular___% The depth of leaching of the gravel is ______ft.
The face of the terrace is fairly straight, but shows some "dimples". A similar terrace, with kettles, occurs on the opposite side of the valley, toward the southwest.
Inferences and questions:
The gravel was deposited by energetic meltwater, close to the ice margin. Could it be, in part, an alluvial fan deposited by Kirkwood Creek up against glacial ice in the valley?
Does the terrace indicate an "advance" Valley Heads position (Muller, 1966), or is it pre-Valley Heads in age? Connally considers it to be the easternmost remnant of Arkport Moraine (1964, p. 43). Just how was it formed? Possibilities include:
a) Deposition by meltwater at the margin of an active ice tongue --an end moraine or lateral moraine, possibly eroded later by meltwater from the Valley Heads ice.
b) Deposition by meltwater between a mass of stagnant ice and the east side of the valley --a typical kame terrace.
c) Deposition of outwash gravel on top of buried stagnant ice in the central portion of the valley; this later melted out, causing the collapse of the gravel in the central portion, but not here at the side (Rich, 1943, p. 98).
d) Deposition of outwash gravel up to the level of the terrace, followed by dissection by a later meltwater stream, leaving the terrace as a remnant of the former high-level outwash deposit.

STOP 9 Rest area on east side of Rt 15
View: Cohocton Valley, an essentially straight, steep-walled, nearly northwest-southeast valley, floored by gravel. The thickness of the gravel, not known, may be obtainable from well logs.
Across the valley is a bench of gravel which attains an elevation of 1480+ ft. It is directly south of Blackcrick Hollow. The face seems to show two levels here; more north of here.
Cohocton Valley is a "through" valley, probably eroded to a large extent by glacial meltwater, as well as by glaciers. According to Fairchild, the preglacial divide was north of Bath (1926, Plate 84). The valley shows truncated spurs, and is floored by a valley train of Valley Heads outwash. Tributary streams have built alluvial fans on top of this outwash.
The gravel bench appears to be a kame terrace, consisting of outwash gravel deposited against stagnant ice. Ice-contact surfaces show especially well on the opposite (southwest) side of the deposit, where it stands free from bedrock. At its southeast end there appears to bean area of collapsed drift.
Is it possible that this gravel bench is, instead, a delta built into a lake in the Cohocton Valley? If so, what held in the lake?
In any case, what caused the two or more levels on the deposit?

Terrace with a concavely curved bank.
Just west of Cohocton, Rt 371 ascends several terraces, one with a concavely curved bank. Could this be the cut bank of a meander, possibly of an outwash stream flowing between ice on the east and the gravel bench on the west?

View ice-contact surfaces

Hinkle Hollow view
Hinkle Hollow Rd at one place is nearly 2100 ft above sea level, affording a good view of the surrounding summit level --inferred by some to be an uplifted peneplain. The till on this hilltop contains relatively few exotics.

Glacial drift
Farther west the road descends into the next north-south valley, containing Loon Lake and much glacial drift in knobs and terraces. Connally identifies this drift as Arkport Moraine (1964, p. 43), which is possibly "advance" Valley Heads Moraine.

North Loon Lake Church kettles
Here, if time permits, a brief stop will be made to view several kettles in a kame terrace. Was each of these formed by a separate block of buried ice, or was there just one large, irregular block? Was
the ice completely or partially buried? How can one tell?

Loon Lake
The road passes Loon Lake, interpreted to be a kettle lake. Note crowding of the lakeshore by cottages. Would it not be better to have the lake and the surrounding area made a park, to be enjoyed by all? This would also reduce pollution of the water and prevent all the interesting gravel deposits from being destroyed!

STOP 10. Rt 21, west of Loon Lake.
Hillside and gravel pit: Irregular, steep gravel slope with hollows and projections. Gravel
is "bright", containing many rounded exotics, somewhat sorted and stratified. A very small percentage of rounded pebbles and cobbles consist of conglomerate containing a variety of pebbles, including crystallines, red sandstones, limestones, and dolomites --all firmly cemented.
The slope is constructional, formed in contact with stagnant ice. The hollows are kettles, and the projections crevasse fillings.
The pebbles and cobbles of exotic-rich conglomerate consist of meltwater-deposited gravel of a previous glaciation cemented during an interglacial time, then eroded during a later glaciation and rounded and deposited by meltwater. Abraded pebbles and boulders of similar conglomerate have been reported from meltwater gravels in several localities in central New York (Schmidt, 1947), and also have been found in till. How much time was required for cementation of this conglomerate to take place? Was an interglacial stage necessary, or would an intraglacial substage have been sufficient? Could it have taken place during minor oscillation of the ice front?

STOP 11. Straight Rd, just west of Price Rd.
Vantage point: Hemlock Lake (left, NNW) and Canadice Lake (right, N). Difference in levels is obvious (905 ft; 1096 ft). These are two of the smallest Finger Lakes, and nearly the farthest west. Both drain northward to the Genesee River.
Sub-accordant summits: hill West of Springwater (WSW) 2060+ ft; Marrowback Hill (NW) 1940+ ft; Bald Hill (N) 1860+ ft. According to Fairchild, Marrowback Hill is capped by Wiscoy shale and Bald Hill by Gardeau sandstone, both Upper Devonian (1928, p. 81).
West of Springwater, a creek descends the valley side in a steep gorge.
The apparent southward confluence of Canadice and Hemlock Valleys suggests former southward drainage, followed by reversal. Did this reversal occur preglacially, as a result of the capture of south-flowing consequent streams by an encroaching north-flowing obsequent stream? Or did it result from glacial deposition in the valleys south of the lakes? VonEngeln implies the latter, and on this basis distinguishes Finger Lakes "West" from Finger Lakes "East" (1961, pp. 27, 38-45). Well logs might throw light on this matter.
The hill summits may represent an uplifted peneplain, although they probably are considerably lower than the former level of this uplifted erosion surface, if there actually is one.
The gorge west of Springwater possibly was eroded chiefly by overflow from a proglacial lake in the south end of the valley of north-flowing South McMillan Creek, on the opposite side of Marrowback Hill. In any case, the gorge is postglacial, interglacial, or both.

Road runs along the delta at the head of Hemlock Lake.

Reynolds Gully
It then passes over a large alluvial fan at the base of Reynolds Gully, a postglacial (or interglacial, or both?) gorge 2 mi north of Springwater.

STOP 12. Rt 15A, 4.6 mi north of Springwater
Overlook:
Hemlock Lake lies in a long, narrow, straight, essentially north-south trough. The depth of the trough, from the top of Marrowback Hill (W) at 1940+ ft to the deepest part of the lake, 809 ft, is 1131+ ft.
Inferences and comments:
The narrowness and straightness of this trough suggest that it was developed from a narrow valley of a relatively small stream. Possibly the trough was preceded by a narrow, steep-walled sluiceway eroded by south-surging meltwater during glacial advance.
Hemlock Lake is a major source of the Rochester area water supply. It is delightfully clear, and makes good canoeing. Note the contrast with Honeoye Lake in regard to the crowding of cottages along the lake shore. Hemlock Lake and Canadice Lake could be the start and nucleus of a Finger Lakes National Park!

B: A COMPARISON OF ENVIRONMENTS
Thomas X. Grasso
Chairman Department of Geosciences
Monroe Community College
The Middle Devonian Hamilton Group in the Genesee Valley
The Devonian System of New York State varies from carbonates at the bottom (Helderbergian and Ulsterian Series) to coarse continental clastics at the top (Chautauquan Series) and represents a westward migrating deltaic complex built during Middle and Late Devonian time, (Rickard, 1964).
This deltaic complex, the Catskill Delta, is today represented by a wedge of sedimentary rock that thickens and coarsens eastward toward the Hudson River. These rocks are highly fossiliferous and structurally simple, thereby, lending themselves to detailed faunal, stratigraphic and paleoecologic studies.
Since the Middle and Upper Devonian of New York represents a deltaic complex, at any instant in time during the Devonian there existed a series of transitional environments aligned approximately parallel to the old shoreline from west to east or offshore deep water to onshore shallow water. These contemporaneous environments are not only transitional with one another laterally, but they also succeed each other vertically since the delta prograded westward across New York State. Each environment is today characterized by its own distinctive rock type and fossil assemblage. For example, the fine shale deposits of the Middle Devonian in the west (Lake Erie) gradually coarsen to siltstones and sandstones eastward (Catskills). The fine shales of the Middle Devonian on Lake Erie are in turn succeeded by the coarser siltstones and sandstones of the Upper Devonian.
The purpose of this field trip will be to sample and contrast several offshore Devonian biotopes representing two major environments; a poorly oxygenated phase of dark shales ("Cleveland" facies), and an oxygenated environment of soft calcareous blue-gray shales and limestones ("Moscow" facies).

B: A COMPARISON OF ENVIRONMENTS

Small ravine on left exposing 11 feet of Onondaga Limestone.

STOP 1. TRIPHAMMER FALLS (Centerfield Mbr.)

STOP 2. Jacox Run
Jaycox Run Section
Centerfield Member
Seven feet of the Centerfield is poorly exposed in the stream bed and small side banks (1-2') just upstream from the old railroad tressel at the base of Jaycox Run. It is mostly a shaly limestone or very calcareous shale at the base of the exposure becoming more shaly and darker upward grading into the Ledyard above. The upper boundary is not a lithologic one but a faunal one being placed at the top of the uppermost abundantly fossiliferous zone (Zone B).
Zone A: The lower part of the exposure is composed almost entirely of microphagous carnivores of bryozoa and corals. Solitary horn corals dominate the assemblage, to the exclusion of almost all other invertebrate species except bryozoans. In this aspect it is almost a coral biostrome and closely parallels those described by Oliver (1951): Heliophyllum halli is very abundant; Amplexiphyllum haniltoniae, Heterophrentis simplex Aulopora sp. are abundant; Favositesalpenensis is common; Favosites hamiltoniae is present. (Descriptive terms for abundance throughout the text from the table on page 11.) The overwhelming domination of microcarnivores certainly means minimal amount of clastic influx with abundant nutrients in shallow, warm, well lighted, agitated waters. Other species are represented by relatively few individuals.
Zone B: Atrypa reticularis Zone: Influx of clastics ended the rugosan-bryozoan domination allowing for the establishment of other feeding groups. Large epifaunal filter feeders dominate this zone especially the brachiopods Atrypa reticularis, (abundant), Mucrospirifer mucrunatus (present) and Megastrophia concava (rare). Vagrant epifaunal forms are conspicuous represented mostly by Platyceras (common) and Phacops rana (present). Corals and bryozoans still survive though reduced in numbers.
Ledyard Member
The Ledyard Member is composed of approximately 57 feet of dark gray calcareous bituminous shale with some black shale interbeds. Calcareous non-septarian concretions mostly small (less than 1 foot in diameter) are abundant at certain intervals throughout the unit. Larger septarian concretions are found toward the top of the Ledyard.
Zone C: Ambocoelia-Chonetes zone: Gradually deteriorating conditions for epifaunal filter, microcarnivore, and infaunal filter feeders beginning during later Centerfield time culminated in their complete removal by Ledyard time. Soft muds high in organic matter allowed infaunal deposit feeders (worm tubes common) and vagrant epifaunal deposit feeders (Phacops rana-common) to flourish initially along with the small filter feeding Ambocoelia (common) and Chonetes (common). Perhaps this interval should be set off as a subzone based on the abundance of Phacops rana. Many of the trilobites are complete, a few are enrolled. They are found nearly parallel with the horizontal, dorsal surface up and some reversed with the ventral surface up. This means that Phacops and to a lesser extent Greenops moved on the substrate plowing or occassionally burrowing into it for food. The fine, bituminous,dark shales in which they are found were soft muds high in organic matter an indication perhaps that Phacops was a deposit feeder.
Zone D: Leiorhynchus Zone: Although this interval is nearly covered, some patches of it are exposed for sampling purposes. It is mostly a calcareous, bituminous, black shale with some dark shale interbedded with it. For all intents and purposes the only species found is Leiorhynchus guadricostatum (very abundant). Anerobic conditions at or above the sediment-water interface existed during the time of deposition of Zone D.
Zone E: (Second Ambocoelia-Chonetes Zone) and Zone F (Phacops rana Zone) are recurrences of Zone C conditions. One unusual addition is a small thin zone at about 75 feet containing the gastropods: Moulonia itys (present), Nauticonemalineata (present), Loxonema hamiltoniae (rare), and Bembexia sulcomarginata (rare), the cephalopod Orthoceras (common), and the infaunal deposit feeding clams Nucula (rare), Paleoneilo (present), and Nuculites triquetor (rare). This deposit feeding assemblage indicates high organic matter in the substrate and oxygen levels high enough to support a diverse molluscan assemblage although composed of mostly small individuals.
Wanakah Member
The Wanakah member is composed of 34 feet of dark gray, bituminous, calcareous shale, succeeded by 1 foot of coarse, silty shale and 11 feet of gray, non-bituminous shale, totaling nearly 46 feet in all.
Zone G: Pleurodictyum americanum Zone: Although no lithologic break separates the Wanakah from the Ledyard Shales, the first appearance of Pleurodictyum americanum is generally taken to represent the lower boundary of the Wanakah (Cooper, 1930). Zone G is a highly fossiliferous zone containing species representative of all feeding groups described. Infaunal deposit feeders are only weakly represented. Well oxygenated conditions must have existed although the bottom sediment was fairly soft. Large epifaunal filter feeders are represented by several forms; Mucrospirifer mucronatus (common); Pterinopecten (very rare); Spinocyrtia granulosa (very rare) being a few.
Stereolasma rectum, the solitary small horn coral is common, apparently the larvae attaching to the shells of other invertebrates (Bray, 1971). Pleurodictyum is present, its larvae attaching to the shells of Loxonema. Aulopora is abundant in a thin layer toward the top of this zone. Small epifaunal filter feeders dominate the assemblage. This assemblage is one adapted to a soft bottom environment; the coelenterates found being those tolerant of turbid water and using the shell of other invertebrates as their "firm substrate" for larval attachment.
Zone H: Modiomorpha subalata Zone: Contained with a thin, coarse, silty, shale bed, capping a small waterfall at 82 feet is the first appearance of abundant infaunal filter feeders. A firmer substrate and increased current activity are probably responsible. The endobyssate bivalve Modiomorpha subalata is common, along with the vagrant gastropod Bellerophon (abundant) and the infaunal bivalve Paleoneilo is common. The silty substrate must have been rich in organic matter to support the infaunal deposit feeders.
Zone I: Mucrospirifer mucronatus Zone: Large numbers of the large epifaunal filter feeder Mucrospirifer mucronatus characterize the succeeding 10 feet of dark bituminous shale on top of the Modiomorpha Zone, Ambocoelia umbonata is common in this interval also. Mucrospirifer mucronatus is characterized by the hinge line extending laterally to form large spines or alae. These presumably functioned like skies to better distribute the weight on a soft substratum. The conspicuous absence of Mucrospirifer from other soft bottom horizons (C, E, & F) leads me to the conclusion that C, E, and F were zones of lower oxygen potentials or less particulate organic matter in suspension and available for food. One other possible explanation is the selective predation of Mucrospirifer larvae during or just before spat fall. This explanation seems to be fairly weak as searching through my mind I cannot conceive of an organism responsible for the selective destruction of just Mucrospirifer larvae.
Zone J: (Second Leiorhynchus Zone): This is a recurrence of Zone D.
Zone K: Third Ambocoelia-Chonetes Zone: This is a recurrence of zones C and E. The Ambocoelia, at least in this zone, seem to occur in clusters. Bray (1969) has dealt with cluster developement in Ambocoelia of the Ludlowville Formation in Erie County. They apparently initiate as a small patch on an otherwise lethal substrate due to their adaptability on soft substrates. Successive generations use the shells of earlier ones to attach the pedicle, thereby increasing the diameter of the cluster. As density increased fecal matter and other toxic substances could have built up to a point inhibiting further spot development and the cluster became extinguished. Other adjacent "immature" clusters would still survive.
Zone L: Stereolasma Zone: The Stereolasma zone represents a trend to more opulent conditions of oxygen, and food supply in the water and substrate. Microcarnivores are represented by Stereolasma rectum (common) vagrants by Phacops rana (abundant) large epifaunal filter feeders by the brachiopods, Athyris spiriferoides (common) Mucrospirifer mucronatus (common).
Zone M: Styliolina fissurella Zone: Bedding planes containing very abundant individuals of the pteropod Styliolina fissurella can be found above Zone L. They appear to represent catastrophic swarm kills with their shells current oriented in a NE-SW direction. Ambocoelia umbonata is abundant in other layers in this zone. A stressed environment of low oxygen, the Styliona zone contrasts markedly with the well aerated waters of the Stereolasma Zone.
Zone N: Nauticonema lineata Zone: This zone represents a recurrence of the gastropod faunal in Zone F. Infaunal filter feeders are most pronouned being represented by Taonurus (present). Infaunal deposit feeding is suggested by the numerous limonite stained worm tubes or trails.
Zone O: Second Mucrospirifer mucronatus Zone: This is a reoccurence of Zone I.
Zone P: Cypricardella-Pseudaviculopecten Zone: At the top of the largest falls in Jaycox Run at 110 feet occurs a foot interval of coarse calcareous silty shale or siltstone. It is characterized by large epibyssate bivalves, endobyssate bivalves, infaunal deposit bivalves, gastropods and brachiopods. This unit presents the highest energy environment of clastic deposition in the Ludlowville Formation of Jaycox Run. Organic material was abundant in suspension, and in the firm substrate. Epibyssates are represented by:
Pseudaviculopecten princeps, (present)
Pterinopecten (rare)
Cyriopecten (rare)
Gosselettia (rare)
Mytilarca (rare)
Endobyssates by:
Cypricardella bellistriata (common)
Actinoptcria decussata -(present)
Leiorpteria conradii (rare)
Modiomorpha mytiloides (rare)
Modiomorpha concentrica (present)
Actinodesma erectum (rare)
Goniphara hamiltoniae (very rare)
Gastropods by:
Moulonia itys (present)
M. lucina (large) (rare)
Nauticonema lineata (rare)
Brachiopods by:
Stropheodonta demissa (present)
Mucrospirifer mucronatus (common)
Mediospirifer audaculus (common)
Infaunal deposit feeders by:
Paleoneilo (common)
Zone Q: Hamilton Fauna: The uppermost 11 feet of the Wanakah member are the most fossiliferous in terms of numbers of species. All feeding types are represented and many species are common to very abundant. A faunal list would be exhaustive; suffice it to say that every common Hamilton form is represented in these 11 feet. This interval represents opulent conditions of temperature, food, substrate, and oxygen. The fossiliferous horizons are separated by a few inches of less fossiliferous shales indicating successive periods of greater deposition separated by the fossiliferous horizons of little or no deposition.
Tichenor Member
Zone R: Tichenor Fauna: The Tichenor Member, a 1 to 2 foot thick hard limestone represents a recurrence of Zone A of the Centerfield Members.
Deep Run Member
Zone S: Crinoidal-Phacops Zone: Zone S encompasses the entire 7 or 8 feet of the blue gray limey shales of the Deep Run Member. Large epifaunal filter feeders represented mostly by crinoids stems and microphagous carnivores by bryozoans are abundant, some endobyssate types are present, epibyssates being rare. Phacops rana is common but extraordinary in size. Some specimens are two to three times the normal size. This fact together with the abundant worm tubes (limonite tubes) suggest abundant organic matter on and in the substrate.
The absence of abundant corals would indicate an environment too turbid for them to become established.
Moscow Formation
Menteth Member
Zone T: Crinoidal Zone: Zone T contains most large crinoid stems. Other feeding tubes are only slightly represented, Phacops rana being the most common vagrant and Taonurus, (common) the infaunal filter feeder.
The assemblage suggests a very turbid high energy environment well suited for filter feeders

Boyd Parker Monument on left.
Site of the murder of Lieutenant Boyd and Captain Parker, two members of General Sullivan's campaign of 1779 against the Iroquois Confederacy to end their continual harassment of colonial frontier settlements in New York. The victims' execution was prefaced by the most insidious torture apparently at the direction of the infamous Mohawk Valley Tory, Colonel Walter Butler.

Genesee Valley Canal
Cross line of the old Genesee Valley Canal which connected Olean with the Erie Canal at Rochester. The Genesee Valley Canal was completed in 1856 and abandoned in 1878. Proceed on U.S. 20A, N.Y. 39.

STOP 3. LITTLE BEARDS CREEK
The Kashong Shale is exposed at this locality and it carries an excellent "Moscow" facies fauna.

STOP 4. TAUNTON GULLY
The upper 20 feet or so of the Windom Member is exposed at the base of the exposure. Upstream from this point there is nearly a continuous exposure from the Leicester Pyrite to the Genundewa Limestone which caps a waterfall at an elevation of about 850 feet.

C: LOWER UPPER DEVONIAN STRATIGRAPHY FROM THE BATAVIA-WARSAW MERIDIAN TO THE GENESEE VALLEY: GONIATITE SEQUENCE AND CORRELATIONS
William Kirchgasser
Department of Geological -Sciences
State University of New York
Potsdam, New York
INTRODUCTION
Previous Work-
The starting point for stratigraphic studies of the Lower Upper Devonian rocks of Western New York is James Hall's (1843) Survey of the Fourth Geological District. In this classic report the names Genesee Slate, Portage Group (with Cashaqua Shale, Gardeau Shales and Flagstones, and Portage Sandstones) became firmly established for the undisturbed and remarkably well exposed sections in and around the Genesee Valley. This far off-shore (basin) succession begins with black and dark gray shales which pass upward into alternating gray, green and black shales, silty gray shales and siltstones, the latter becoming predominant toward the top.
Although little remains of Hall's original subdivision his preliminary observations provided the framework for later detailed stratigraphic studies and the monographs of the rich faunas which these rocks contain (Hall, 1879; Clarke, 1898, 1904). Among the various elements of the chiefly pelagic and molluscan "Naples Fauna" the goniatite cephalopods have received the most attention. Although they lack the diversity of their Eurasian contemporaries, the goniatite faunas from New York have special value because their stratigraphic position and sequence can be rather precisely determined. The correlation of the New York succession with the European standard, by means of goniatites and conodonts, is now generally established (Fig. 1) although a few discrepancies and details still need to be worked out.

C: LOWER UPPER DEVONIAN STRATIGRAPHY FROM THE BATAVIA-WARSAW MERIDIAN TO THE GENESEE VALLEY: GONIATITE SEQUENCE AND CORRELATIONS

STOP 1: BETHANY CENTER, N. Y.
Park below the overpass at right turnoff to Bethany Center.
Walk down hill on north side of Rt. 20 and observe loose blocks of Genundewa Limestone on the embankment. Although the rocks are weathered and picked over, this remains one of the best collecting sites for the fauna of the Genundewa Limestone. In addition to the ubiquitous Styliolina, the more common fossils are species of pterochaenia and Bactrites, Tornoceras (T.) uniangulare compressum and forms referable to Manticoceras styliophilum. The less weathered blocks of limestone yield abundant conodonts when digested in dilute acetic acid.

STOP 2: LINDEN, N.Y.
Walk to edge of Little Tonawanda Creek and observe section of lower Genesee Formation (Geneseo, Penn Yan and Genundewa members) in falls of side creek (Fig. 4A-B) (Private Property).
The contact with the underlying Moscow Formation is at about creek level. At this locality the Geneseo-Penn Yan interval is 31 feet thick; at Eighteenmile Creek near Lake Erie this same interval is less than 0.5 feet thick and on the east side of the Genesee Valley (Stop 7) it is 80 feet thick.
The Geneseo-Penn Yan contact is drawn at the top of a pair of black shales Which outcrop in the face of the falls; the horizon of these shales has been traced westward to Cayuga Creek and eastward to the east side of the Genesee Valley. Manticoceras first appears in the Penn Yan Member in a concretion horizon 8.5 feet below the base of the Genundewa Limestone, which caps the falls. Tornoceras (T.) uniangulare compressum and forms referable to Manticoceras styliophilum are common in the Genundewa Limestone in this area.

STOP 3: WYOMING GULF.
Park on right (S) side of road at jct. with Wass Road (on right).
Contact between Cashaqua and Rhinestreet Shales occurs in road cut above the intersection.
The dark shale facies of the upper Cashaqua is rather poorly exposed here but the characteristic fossil Pterochaenia cashaquae is common at some levels; The horizon of baritic septaria which characterizes the uppermost Cashaqua is not exposed at this locality. A 3 inch thick black shale about 10 feet below the base of the Rhinestreet has been traced in about the same position from Lake Erie to Honeoye Lake.
Walk down the hill and observe roadcuts (or stream section) of the concretion facies of the Cashaqua. The following fossils are common in olive green shales and concretions: Styliolina fissurella, Buchiola retrostriata, Paracardium doris, pterochaenia sp., Protospirialis minutissima, Bactrites aciculum and Probeloceras lutheri. Less common are: Ontaria suborbicularis, Loxonema noe, Palaeotrochus praecursor, Spathiocaris emersoni (crustacean), Tornoceras (T.) uniangulare obesum and Manticoceras sinuosum.
In general the fauna is dominated by small shells and is less diverse than the Naples Fauna in the nodule facies of the Cashaqua around Canandaigua and Keuka Lakes where in more arenaceous, current-reworked, and probably shallower water sediments, the larger bivalves such as Lunulicardium, Ontaria, and Honeoyea were important elements.

STOP 4. STONY CREEK.
Park beyond RR tracks opposite RR station. Cross Rt. 20A (CAUTION) and walk 0.5 miles SOUTH along RR tracks to Stony Creek. Climb down embankment to left of bridge.
CAUTION: STAY OVER TO LEFT, AWAY FROM THE FALLS!!
Observe section in middle part of West Falls Formation (Figs. 2, 5). At this meridian, the western Angola shale facies (member) interfingers with the more arenaceous Gardeau facies. The succession consists of silty gray shales interbedded with siltstones black shales and concretion horizons. The siltstones, many of which are crossbedded and ripplemarked, are thicker and more numerous toward the top of the section.
The black shale above the Scraggy Bed, which marks the Rhinestreet-Angola contact around Lake Erie, is represented in this section by a 3 foot 9 inch bed of black shale, 22 feet below the top of the 1 foot thick siltstone capping the main falls. The Gibson's Glen Goniatite Bed (Stop 5) occurs lower down, 25 feet below the base of the Scraggy Bed black shale, in rocks equivalent to the Upper Rhinestreet of westernmost New York. The Point Breeze Goniatite Bed, which has been traced from its type exposure on Lake Erie shore, occurs 7.5 feet above the 1 foot thick siltstone in rocks equivalent to the Lower Angola Shale to the west.

STOP 5 RELYEA CREEK.
Section commences at edge of farm field, 500 yards west of Rt. 19 at c. 1100 feet altitude. (Private property).
Description The Gibson's Glen Goniatite Bed, noted for its well preserved specimens of Manticoceras rhynchostoma, outcrops in the face of the low falls about 100 yards upstream from start of section (Fig. 5); goniatites are also common in concretions about 5 feet above the top of the falls. The Scraggy Bed black shale outcrops about 100 yards farther upstream, about 2 feet above the base of the high falls. The Point Breeze Goniatite Bed occurs in the face of the falls, about 23 feet higher, beneath an 11 inch thick siltstone.

STOP 6. TAUNTON GULLY.
Park on right side of Rt. 36 and cross the highway (CAUTION). The bus will proceed to rendezvous point at top of section. Those who do not wish to walk the entire creek section (about one mile) may stay on the bus:
Section commences in Geneseo shale member (Genesee Formation) above Leicester Pyrite, about 2000 feet west of RR bridge at 730 feet elevation (Fig. 4B).
Styliolina fissurella and pterochaenia fragilis occur in the gray shales and thin argillaceous limestones above the basal black shales of the Geneseo and poorly preserved Ponticeras perlatum and Tornoceras sp. are not uncommon in the most prominent limestone outcropping 17 feet above the base of the member. This limestone is also recognized at White Creek, Beards Creek, and Fall Brook.
The Geneseo-Penn Yan contact is drawn at the top of a pair of black shales about 4.5 feet above the 10 inch black shale near the level of the pool at the base of the main falls. The bed of small nodules immediately below the lower member of the pair of black shales contains rare Ponticeras in the Beards Creek and Fall Brook sections. Forms referable to Ponticeras perlatum occur in the concretion horizon 3 feet below the 1 foot interval of thin styliolina limestones which form the lip of the falls; similar limestones are frequent higher in the Penn Yan member.
Manticoceras first appears in the section in a 2 foot interval of concretions and nodules beneath a 5 inch black shale, 16 feet below the base of the Genundewa limestone member. Probeloceras genundewa occurs in the topmost beds of the Genundewa which outcrop a few feet upstream from the road bridge.

Bridge over Taunton Gully; rendezvous point.

STOP 7 -DEWEY HILL
Roadcut exposes upper Penn Yan shale and Genundewa limestones members (Genesee Formation) (Fig. 4B)
The Geneseo and Penn Yan members are well exposed in the classic section in nearby Fall Brook but most of the Penn Yan is inaccessible except in the side creek. In the road section the Penn Yan is characterized by silty gray shales interbedded with many thin argillaceous limestones and a few concretion horizons. Several of the thin limestones are composed almost entirely of Styliolina fissurella.
Poorly preserved goniatites identified as Manticoceras and Tornoceras occur in a 4.5 inch thick limestone above the interval of concretions near the base of the section, and similar forms occur about 3 feet higher in the lowest member of a set of three Styliolina limestones.
The Genundewa limestone, which caps the Falls at Fall Brook, outcrops at the crest of the hill.

D: EURYPTERID HORIZONS AND THE STRATIGRAPHY OF THE UPPER SILURIAN AND ?LOWER DEVONIAN OF WESTERN NY
Samuel J. Ciurca, Jr.
Rochester, New York
Introduction
The Upper Silurian rocks of New York State comprise an interesting variety of distinct lithologies, e.g. red and green shales, some sandstone, limestone and dolostone, halite, gypsum, and anhydrite. While these rocks are of economic importance because of the halite and gypsum deposits they contain, much of current geologic interest in these strata is concerned with their sedimentology, correlation, and more recently, the paleontology of certain well-known fossiliferous units (see, for example, Treesch 1972, Rickard 1969, Berry and Boucot 1970, Berdan 1972). Often overlooked is the unusual eurypterid and scorpion faunas which these generally "unfossiliferous" rocks contain.
The purpose of this article and associated field trip is to familiarize the reader with the Upper Silurian and ?Lower Devonian rocks of the Genesee region, particularly the Bertie Group, and to examine outcrops of these rocks at localities which have yielded eurypterid remains.

D: EURYPTERID HORIZONS AND THE STRATIGRAPHY OF THE UPPER SILURIAN AND ?LOWER DEVONIAN OF WESTERN NY

STOP 1. Oaks Corners Quarry

STOP 2

STOP 3.

STOP 4.

STOP 5. Mud Creek

STOP 6. Bridge over Honeoye Creek

STOP 7. Sewage Treatment Plant

Rock fences primarily of Cobleskill Fm. some stromatoporoids, rare favosite coral

STOP 8. Neid Road Quarry
Town of Le Roy Metal Refuse Disposal

Quarry in the Onondaga Fm.
Entrance to General Crushed Stone Co.-Le Roy plant.

STOP 9. Brief stop
Steam shovel used from 1906-1949 - also small locomotive and car for carrying stone.

Quarries in the Onondaga Fm. on both sides of the road

STOP 10. LAST STOP

E: LATE GLACIAL AND POSTGLACIAL GEOLOGY OF THE GENESEE VALLEY IN LIVINGSTON COUNTY, NEW YORK: A Preliminary Report
RICHARD A. YOUNG
Department of Geological Sciences
SUNY, Geneseo, N.Y.
WENDELL D. RHODES
Department of Anthropology
INTRODUCTION
Geologic and archaeologic investigations in the Genesee Valley have produced evidence of glacial drift blockage (moraine?) within the valley, followed by floodplain aggradation up to 95 feet above the modern river bed. The terraces may have been formed between 2500 and 4400 years ago between Avon and Mt. Morris, New York. The exact manner of emplacement of the abnormally thick till section in the valley is unclear, but the resulting postglacial fluvial aggradation and subsequent terracing appear to correlate in a general way with the periods of neoglacial climatic fluctuation discussed by Denton and Porter (1970).

E: LATE GLACIAL AND POSTGLACIAL GEOLOGY OF THE GENESEE VALLEY IN LIVINGSTON COUNTY, NEW YORK: A Preliminary Report

STOP 1. Cross ice marginal drainage channel

Turn west on Cheese Factory Road following ice marginal channels

Cross Honeoye Creek
Cross Honeoye Creek on approach to Sibleyville, Honeoye Creek occupies ice marginal drainage at this point.

STOP 2. View esker, kettles, and kames at Round Pond

STOP 3. Warren Shoreline
Oak Opening Road follows Warren Shoreline north-south across Routes 5 & 20

STOP 4. Beach along wave eroded drumlin(?) on south side of highway

STOP 5. Gravel pit on west bank near large glacial drainage
Gravel pit on west bank near large glacial drainage which discharged SE into Genesee Valley. View drainage features and gravels mapped as deltas by Fairchild (1909).

STOP 6. For 1/2 mile cross remnant of delta-like deposits
For 1/2 mile cross remnant of delta-like deposits at 580 feet at Conesus Outlet stream which might have been deposited into lake waters prior to the formation of Lake Scottsville at 540 feet. Alternatively it could represent the remnant of a higher floodplain in the Genesee Valley 40 feet above the modern floodplain (See discussion regarding Genesee Valley terraces)

STOP 7. Bridge over river near Fowlerville: view valley profile and till outcrop

STOP 8. Avon landslide of April, 1973
2012: Best GE image from 3/23/2010

STOP 9. Lunch at Dept of Geol Sciences, Geneseo.
View maps, aerial photographs, etc.

STOP 10. Archaeology site in Genesee River terraces
Turn west toward river through field to Archaeology site in Genesee River terraces near confluence with Canaseraga Creek.

F: THE PINNACLE HILLS AND THE MENDON KAME AREA: CONTRASTING MORAINAL DEPOSITS
Robert A. Sanders
Department of Geosciences
Monroe Community College
The Pinnacle Hills, fortunately, were voluminously described with many excellent photographs by Fairchild, (1923). In 1973 the Range still stands as a conspicuous east-west ridge extending from the town of Brighton, at about Hillside Avenue, four miles to the Genesee River at the University of Rochester campus, referred to as Oak Hill. But, for over thirty years the Range was butchered for sand and gravel, which was both a crime and blessing from the geological point of view (plates I-VI). First, it destroyed the original land form shapes which were subsequently covered with man-made structures drawing the shade on its original beauty. Secondly, it allowed study of its structure by a man with a brilliantly analytical mind, Herman L. Fairchild. It is an excellent example of morainal deposition at an ice front in a state of dynamic equilibrium, except for minor fluctuations.
The Mendon Kame area on the other hand, represents the result of a block of stagnant ice, probably detached and draped over drumlins and drumloidal hills, melting away with tunnels, crevasses, and perforation deposits spilling or squirting their included debris over a more or less square area leaving topographically high kames and esker segments with many kettles and a large central area of impounded drainage. There appears to be several wave-cut levels at around the + 700 1 Lake Dana level, (Fairchild, 1923).
The author in no way pretends to be a Pleistocene expert, but an attempt is made to give a few possible interpretations of the many diverse forms found in the Mendon Kames area. Fairchild's work (1923) on the Pinnacle Range seems to need little in the way of additional interpretation.

F: THE PINNACLE HILLS AND THE MENDON KAME AREA: CONTRASTING MORAINAL DEPOSITS

Eggs-in-a-basket kames.

More non-ice-contact kames.

Driving along sub-lacustrine outwash slope.

Cross Clinton Avenue South pit on left.

Kame appears to be ice-contact on north outwash slope.

Circle Reservoir
Circle Reservoir overlooking Rochester till plain to north and Lake Dana basin to south (if clear, may see Bristol Hill-south shore of Lake Dana) Pinnacle Hill high point to west with T.V. towers.

Climbing up Salina Group.

Notice swell and swale topography-both sides.

Notice Drumlins on both sides of road.

Notice collection of erratics on house below on right.

STOP 1. Clover Sand & Gravel Co.
Large cut in esker cone showing torrential bedding.

STOP 2. Get out of bus for walk on esker.

Get back on bus at Devil's Bathtub parking lot

STOP 3. Eggs in a basket, etc.
Look at eggs-in-a-basket kames (non-ice-contact) and edge of kettle with sharp break in slope-(ice-contact).

STOP 4. Entrance to Shafer's Pit
Entrance to Shafer's Pit in large-till-capped? kame, probably draped over drumlin.

STOP 5. Walk on esker segment in east side of park.

STOP 6. View of dissected ice-contact kames.

STOP 7. Optional. Right turn in Russo's pit.
Look at catastrophic bedding overlying pre-glacial Genesee River (?), truncated by ice-marginal drainage channel of Lake Warren II, get on bus for trip back to motel.

G: PLEISTOCENE AND HOLOCENE SEDIMENTS AT HAMLIN BEACH STATE PARK, NY
Robert W. Adams
State University College at Brockport
Erosion and sedimentation along the Lake Ontario shore at Hamlin Beach State Park, ten miles north of Brockport, New York, have exposed and produced numerous sedimentological features. The purpose of this trip is to examine Pleistocene and Holocene deposits in order to observe the variety of materials and structures present and to discuss their possible origins. The high water level condition of Lake Ontario and periodic lake storms have created new exposures of Pleistocene deposits and have removed or made inaccessible other exposures. This situation is not expected to change prior to the field trip and therefore specific localities cannot be designated in this summary. The general types of material which we may reasonably expect to examine are outlined below. It is hoped that the experience of the participants and discussions on the "outcrop" will aid in the interpretation of the Pleistocene features.

Hamlin Beach State Park

H: MINERAL COLLECTING AT PENFIELD QUARRY
William A. Bassett
Gary L. Kinsland
Department of Geological Sciences
University of Rochester, Rochester, N.Y.
ABSTRACT
Penfield Quarry, Penfield, N.Y., is in the dense gray Lockport Dolomite and is operated by Dolomite Products as a source of material for road construction. A large variety of nicely crystallized minerals occur in solution vugs as well as cavities associated with corals in the upper portions of the formation. Some of the finest specimens to come from this locality are variously colored fluorite cubes, very clear gypsum, reddish brown sphalerite crystals, celestite crystals, and vugs lined with dolomite and calcite crystals. The origin of these minerals is a subject that can lead to lively discussions.

STOP 1. Penfield Quarry
Lockport Dolomite
The Lockport Dolomite is a hard, dense, fine grained dolomitic limestone of Middle Silurian age. It is quarried and crushed by the Dolomite Products Company for use in road construction. Its resistance to erosion has led to the formation of an escarpment that is a rather prominent feature running west from Rochester to Niagara Falls where it forms the crest of the falls. From there it runs west through Ontario and Michigan. In places it is argillaceous. It is also very petroliferous and has a strong odor of crude oil when broken. Black encrustations and blobs of natural asphaltum are abundant. At Rochester the Lockport Dolomite has a total thickness of approximately 180 feet. Fossil corals are commonly found in some layers but are not easily removed from their matrix. Solution has produced cavities and stylolites which in turn have served as hosts for much of the mineralization.
Mineralization
In spite of numerous outcrops and extensive quarrying of the Lockport Dolomite, there are only certain localities that offer the variety of minerals and well developed crystals found at the Penfield Quarry. The best known of these are the Royalton Stone Quarry east of Gasport on route 31, Frontier Quarry southwest of Lockport, the piles of rubble taken from the Barge Canal excavation at the east edge of the Monroe County Airport and just west of Lockport, and the Walworth Quarry east of Rochester. The minerals described below occur as crystals and encrustations lining the inner surfaces of the solution vugs, fissures, and corals found in the Lockport Dolomite. One reason that the mineral specimens from these localities have been very popular among collectors is the fact that they have formed as crystals growing rather freely into solutions that filled these spaces. The sequence of crystallization among the minerals has resulted in particularly interesting relationships. For instance, calcite crystals are commonly found on top of the dolomite crystals whereas dolomite crystals are commonly found embedded in clear gypsum. The availability and quality of the minerals at the Penfield Quarry vary considerably with time as the quarry workings traverse certain zones.
Anhydrite CaSO4 Orthorhombic mmm
Light blue masses often found completely filling vugs and enveloping other minerals, commonly mixed with fine grained white gypsum. These masses are often found to be somewhat foliated. The gypsum may be an alteration of the anhydrite.
Aragonite CaCO3 Orthorhombic mmm
Sometimes found as white crusts.
Barite BaSO4 Orthorhombic mmm
Distinguished from the more common celestite with certainty only by flame tests or X-ray diffraction. It has an occurrence similar to that of celestite.
Calcite CaCO3 Trigonal bar 3 2/m
Scalenohedral crystals (dog tooth) are sometimes found as large as 15 centimeters; more commonly 2-5 centimeters. Also occurs as beautiful micro-crystals of rhombohedral habit and unusual clarity associated with marcasite on the dolomite. Scalenohedral crystals commonly occur on the dolomite oriented in such a way as to permit firmly attached doubly terminated specimens. Best large specimens are found in dolomite-lined vugs with little else present.
Celestite SrSO4 Orthorhombic mmm
Light blue to white to colorless, translucent to transparent, elongate crystals. A light blue color is fairly indicative of celestite. The colorless crystals may be barite. Often found enveloped by gypsum; beautiful specimens with celestite penetrating transparent gypsum can be found. Crystal size from millimeters to approximately 0.3 meters.
Dolomite CaMg(CO3)2 Trigonal bar 3
Nice translucent white rhombohedral crystals with curved faces lining cavities are a certain find for anyone visiting Penfield Quarry. Crystals are commonly 0.5 -1 centimeter in size and situated so as to show faces. Smaller colorless transparent rhombohedrons may also be observed with a lens and distinguished from calcite by acid.
Fluorite CaF2 Isometric m3m
The most prized specimens from Penfield Quarry are those with free-standing fluorite cubes. They range in size from less than a millimeter to approximately 10 centimeters on a side, though most are in the 1-2 centimeter range. Color ranges from colorless to yellow to green to blue to purple making these especially attractive specimens. Many of the examples exhibit especially fine banding which can be seen in three dimensions within the crystals. The best crystals are found free-standing in vugs lined with white dolomite crystals which make the fluorite colors stand out vividly.
Galena PbS Isometric m3m
Rare. Occurs imbedded in the gray dolomite rock, more rarely as free standing cubes in cavities.
Gypsum CaSO4•2H2O Monoclinic 2/m
Occurs as fine grained white masses as well as the selenite variety of unusual clarity. Some selenite masses are as large as 0.3 meter in length. Occasionally crystal faces can be found. Selenite commonly envelops other crystals, notably celestite and dolomite producing quite nice specimens. Both varieties of gypsum commonly fill entire cavities.
Marcasite FeS Orthorhombic mmm
Small cockscomb masses and singly or doubly terminated crystals usually less than 3 millimeters in length. Most are tarnished to a brilliant iridescent blue; some are pale bronze-yellow. Usually found on dolomite crystals and sometimes imbedded in gypsum.
Pyrite FeS2 Isometric 2/m bar 3
Small cubes and pyritohedrons less than 2 millimeters. Other forms may be present as well. Usually brass-yellow, sometimes tarnished iridescent blue. Usually found on dolomite crystals with little else near except marcasite and colorless rhombs of calcite.
Quartz SiO2 Trigonal 32
Skeletal masses of drusy micro-crystals. Distinguishable in hand specimens from similar masses of dolomite by sparkle and from similar masses of calcite by acid test. Hardness is not applicable because the individual crystals are of the order of tenths of a millimeter. With a hand lens and a careful eye, identification based on crystal forms is possible in some cases. All three minerals may occur together.
Sphalerite (ZnFe)S Isometric bar 4 3m
Variable in color from light yellow to red to dark brown depending on iron content. Occurs as veinlets in the dolomite rock and as curved, thick, fan-shaped crystals that are free-standing in the vugs. The crystals are often a centimeter or more across.
Strontianite SrCO3 Orthorhombic mmm
Sometimes found associated with celestite.
Sulphur S Orthorhombic mmm
Occurs rarely as surface coatings and masses and as micro-crystals.

I: STRATIGRAPHY OF THE GENESEE GORGE AT ROCHESTER
Thomas X. Grasso
Monroe Community College
The Genesee River, in its northward flow to Lake Ontario, plunges over the Niagara or Lockport Escarpment at Rochester. Diverted from its preglacial outlet through Irondequoit Bay, the Genesee River, since the last ice retreat (8,000 years ago) has carved a post glacial gorge exhibiting a nearly complete exposure of Upper Ordovician to Middle Silurian rocks. Formations of the same age are superbly exposed in the Niagara Gorge and a comparison of the two sections reveals a Lower and Middle Silurian section ideally suited for the illustration of complex facies changes and/or disconformities.

STOP 1. Lower Falls and Gorge
Down from Seth Green Drive at St. Paul and Norton Streets, on east side of gorge below Driving Park bridge.
Group
Formation
Member
Lower Clinton
Reynales
Wallington Ls.
Furnaceville Hematite
Hickey Corners Ls
Maplewood Shale
Thorold Ss.
Medina
Grimsby Fm.
Queenston Fm.

STOP 2. Middle Falls and Gorge
At the bottom of Brewer St. down from St.Paul Street on east side of river; south of Driving Park Bridge and North of the Bausch Bridge (Smith St. Bridge)
Group
Formation
Member
Upper Clinton
Rochester Shale
Irondequoit Ls.
Williamson Shale
Lower Clinton
Lower Sodus Shale
Reynales Ls.
Wallington Ls.
Furnaceville Hematite
Hickory Corners Ls.
Maplewood Shale |

STOP 3. Upper Falls and Gorge
Down from Mill St. and Falls St., on access road to Rochester Gas and Electric Power Stations 2 & 3, on west side of gorge below Platt Street bridge
Group
Formation
Member
Lockport | Decew Dolomite |
Clinton | Rochester Shale |