NYSGA 1992.kml
New York State Geological Association
64th Annual Meeting
Richard H. April, Editor
Field Trip Guidebook
Department of Geology
Colgate University
Hamilton, NY 13346
Published by the New York State Geological Association.
Additional copies may be obtained from the permanent Executive Secretary, James F. Olmstead, Center for Earth and Environmental Science, State University of New York, College at Plattsburgh, Plattsburgh, New York 12901.
Step out onto the Planet.
Draw a circle a hundred feet round.
Inside the circle are
300 things nobody understands, and, maybe
nobody's ever really seen.
How many can you find?
Lew Welch

A1: THE TRENTON - UTICA PROBLEM REVISITED: NEW OBSERVATIONS AND IDEAS
Gordon C. Baird
Dept of Geosciences, SUNY Fredonia
Fredonia, NY 14063
Carlton E. Brett and David Lehmann
Dept. of Geological Sciences, University of Rochester
Rochester, NY 14627
INTRODUCTION
The Middle to Upper Ordovician Trenton Limestone and Middle to Upper Ordovician black (Utica-type) shale which overlies it in New York State and Southern Ontario have been of considerable interest to geologists since the time of James Hall. This attention is due to the paleontological richness of the Trenton carbonates and early recognition of the facies equivalency of part of the Trenton with black shale deposits in the Mohawk Valley. More recently, heightened interest in Trenton-Utica stratigraphy, sedimentology, paleoecology, and tectonic processes reflects recognition that these sediments are synorogenic. The closely associated Taconic Orogeny represents an arc collision event involving subduction-related emplacement (overthrusting) of an accretionary prism (Taconic Allochthon) over the margin of the Laurentia craton. This emplacement was followed by orogenesis associated with collision, suturing, and uplift of the Vermontia Terrane (Bird and Dewey, 1970; Rowley and Kidd, 1981; Lash, 1988). This paleosetting is believed to be analogous to the present day subduction of the Australian Sahul Shelf under the Banda Arc with the Taconic basin correlating to the foredeep south of Timor. In this context, the Trenton to Utica transition records the collapse of a cratonic platform owing to subduction and thrust load-related down-bending of the craton as the orogeny proceeded. Evidence for this down buckling is manifest in the Middle-Upper Ordovician succession in central and eastern New York as an upward- and eastward facies change from carbonate platform deposits to basinal facies.. Furthermore, numerous normal faults cross-cut the Trenton, which are believed to have been active mainly as synthetic (down to the east) and antithetic (down to the west) displacements reflecting lithospheric responses to subduction (Bradley and Kidd, 1991). Many of these faults are believed to have been active during the tectonic foundering of the Trenton shelf, resulting in a complex "patchwork" stratigraphy for upper Trenton and lower "Utica" units in the Mohawk Valley (see Cisne and Rabe, 1978; Cisne, etal., 1982; Bradley and Kidd, 1991).
Ruedemann (1925), Ruedemann and Chadwick (1935), and Kay (1937, 1953) mapped Trenton and Utica deposits across this region and recognized that uppermost Trenton units (Rust, Steuben, and Hillier limestones) progressively disappeared to the east and southeast of Lowville, NY Medial Trenton strata (Denmark Limestone) distinctly grade from richly fossiliferous carbonates at Trenton Falls (Poland and Russia members) through a belt of fossil-poor thin-bedded calcilutite facies (Dolgeville Member) to predominantly dark gray or black fissile Utica-type shale (Canajoharie Shale) near Canajoharie, New York. Lower Trenton units (Napanee, King's Falls, Sugar River Formations) were observed to remain fossil-rich across central New York. However, there is an eastward thinning of these lower strata east of Dolgeville, NY, possibly due to submarine erosion. West of Canajoharie, NY the Trenton Limestone is locally missing (see Kay, 1953; Fisher, 1977; Cisne, and Rabe, 1978).
In two important publications, Cisne and Rabe (1978); and Cisne et al. (1982), presented results of highly refined paleoecologic work on Trenton and Canajoharie deposits using volcanic ashes (metabentonites) as correlation isochrons (Figure 1). In so doing, they were able to subdivide the Trenton into thin, time-constrained divisions which could be followed eastward into black shale. Quantitative gradient analysis of fossil associations indicated that this was no steady eastward-sloping ramp; normal faults were believed to have been active in latest Trenton time such that a horst and graben topography was developed and submarine fault scarps existed locally (Cisne and Rabe, 1982).
Controversies concerning Trenton, Canajoharie, and Utica stratigraphy in New York arose early in the study of these units. Although some divisions can be correlated over long distances, abrupt facies changes, losses of units, and appearances of units over small distances have long been noted (see discussions in Ruedemann, 1925; Ruedemann and Chadwick, 1935; Kay, 1937, 1953; Cisne, et al., 1982; Titus, 1986, 1988). The most prominent problem involves Trenton and lower Utica Shale stratigraphy in the interval between Trenton Falls and Middleville, a 16 km wide region northeast of Utica characterized by thick surficial cover and incomplete sections. Another problem is the meaning of sharp lithologic contacts in sections where bioclastic Trenton carbonates are abruptly overlain by dark argillaceous strata (Canajoharie Shale, Utica Shale) or by sparsely fossiliferous ribbon limestones (Dolgeville facies). The presence of such contacts has long been noted, but there is disagreement concerning their extent, age, and significance (see discussions in Kay, 1953; Riva, 1969; Fisher, 1977, 1979; Cisne et.al., 1982; Titus, 1990). Very recently, parts of the metabentonite correlation scheme of Cisne and Rabe (1978) have been called into question owing to new "fingerprinting" correlation techniques for ash identification. This problem, coupled with the unstable existing stratigraphies of Kay (1953), Fisher (1977), Cisne et al.(1982), and Titus (1990), poses the need for continued field study of these rocks but with the application of new approaches and perspectives.
The interest of the present authors of the Trenton-Utica problem stems both from our interest in the relationships of black shales in foreland basins to surrounding facies and from our use of stratigraphic event-horizons in establishing refined correlations in the Silurian and Devonian as well as for Upper Ordovician strata of Ontario and north-central New York. Important to this approach is the recognition of sedimentary cycles of varying magnitude in these younger deposits which owe their origin to eustatic sea level changes (Brett and Baird, 1985; Brett et al., 1990b ). Also relevant to Trenton mapping is the discovery of widespread submarine discontinuities of varying magnitude which define mappable stratigraphic packages of great lateral extent (Brett and Baird, 1986a; Brett et al., 1990a, b). It is our goal to define, firstly, the widespread major discontinuities both within and bounding the Trenton, Canajoharie, and Utica, and secondly, the sedimentary cycles and distinctive cycle-capping condensed units within these large discontinuit-ybounded packages. Preliminary results of this work are presented below.
We are particularly attracted to the sharp erosional bases of the Ordovician black shales. Our work on Late Ordovician, Silurian, and Devonian black shale-roofed erosions contact shows that they reflect erosional processes occurring predominantly under basinal conditions of prevailing near-anoxia (Baird and Brett, 1986a, b; Baird et al., 1988; Baird and Brett, 1990; Lehmann and Brett, 1991a, b). Preliminary work on Dolgeville, Canajoharie, and Utica discontinuities is presented herein; it shows that these contacts are mappable and significant. A very large and widespread discontinuity herein informally designated the "Sub-Utica Disconfonnity" may be an Ordovician analog of an erosional overlap surface which floors Middle and Late Devonian black shale deposits across numerous eastern states.

A1: THE TRENTON - UTICA PROBLEM REVISITED: NEW OBSERVATIONS AND IDEAS

STOP 1. West Canada Creek, Prospect:
Slump folds and obrution deposits in the Rust Member, Denley Limestone.
A nearly continuous, although faulted exposure, of middle and upper Trenton strata crops out in the West Canada Creek gorge from the village of Trenton Falls to the Prospect Dam (approximately 3.5 km of exposure). At this stop, we will examine the upper 15 m of Rust bioclastic limestones and the lower 5 m of Steuben calcarenites. A number of interesting and enigmatic sedimentary and taphonomic features are present in this interval.
Note the prominent slump fold horizon (the "upper disturbed zone" of Prosser and Cummings, 1897) in the upper Rust, approximately 5 m above stream level along the east wall of the gorge. Disturbed strata occur as intermittent pods or lenses. Within lenses, strata are folded, brecciated, and -- in some cases -- over-thrusted. Lenses of disturbed strata are typically bounded by, and merge laterally into, shaley horizons, some of which contain slickensides. Some of these shales form rusty, micaceous recessions in the outcrop; they may be metabentonites. This interplay of ductile and brittle deformation suggests that strata were fairly well lithified when they were deformed (Mehrtens, 1984).
This disturbed zone is clearly continuous from Poland to Remsen, a distance of 12 km. Furthermore, "disturbed" strata occur at approximately the same stratigraphic position from Remsen to Lowville, 45 km to the northwest. This widespread occurrence of upper Rust disturbed strata, suggests that deformation reflects some sort of regional event--probably oversteepening of the Trenton ramp/platform.
The timing and nature of this oversteepening event is problematic. Unlike the slump folds in the uppermost Dolgeville (see Stop 6), these slump folds seem to indicate a down-to-the-east paleoslope (Cisne and Rabe, 1978). Although these slump features are clearly post-depositional, sediment was not completely lithified during deformation. Potentially, water released during compaction of clays accommodated the ductile behavior of the limestone beds; the disturbed zone incorporates a particularly shaley horizon of the Rust. Clearly, water content of the muds, amount of overburden, and angle of slope all played important roles in this slump deformation.
How might this slumping have been influenced by tectonic activity? Cisne et al. (1982) and Mehrtens (1988) have suggested that middle Trenton sediments were deposited in a developing foreland basin in which subsidence was accommodated by movement along the numerous normal faults which are present in the Mohawk Valley region. One such fault, which displaces Trenton strata 35 m, is located 150m upstream of the Prospect Bridge. A narrow gully occupies the surficial position of the fault. In the south wall of the gully, Steuben grainstones crop out. In the north wall of the gully, nodular limestones of the lower Rust are present. The northern exposure also contains abundant slickensides. The fault shows reverse polarity. However, drag folds associated with this fault indicate original normal, down to the east displacement; a net reversal of displacement apparently occurred at a later time (Bradley and Kidd, 1991). Tectonically-induced subsidence could have resulted in an oversteepened platform. Interestingly, the disturbed zone is cross-cut by a number of faults suggesting that either: 1) most motion along these faults occurred after slump folding, or 2) synchronous displacement along these faults -- possibly related to thrust loading -- resulted in widespread regional slumping.
Alternatively, Titus (1986) suggests that upper Denley (Rust) to Steuben deposition reflects upbuckling of the western Adirondack Arch region. In this scenario, oversteepening could accompany the basin modification. However, down-to-the-east slump features would suggest that the axis of uplift was to the west of Prospect
Waltherian relationships suggest that the Rust strata at this outcrop represent deposition below normal wave base but possibly not below storm wave base. Lower Rust strata above High Falls at Trenton Falls contain wave ripple marks, while interference ripple marks and hummocky cross stratification occur in the Steuben grainstones at Cincinnati Creek (4 km to the northwest of here). Thus upper Rust strata are conformably bracketed by deposits representing storm-dominated shelf and wave base settings. Airy wave theory analysis of ripple marks of this stratigraphic interval at Booneville (25 km to the northwest) suggests sediment was deposited in water depths of between 1 and 27 m at that locality.
The occurrence of a diverse epibenthos and ichnofauna suggests well oxygenated seafloor and substrate conditions. The nodular bioclastic upper Rust Member contains abundant specimens of the brachiopods Rafinesquina deltoidea, and Platystrophia sp., the bryozoan Prasopora orientalis, and echinoderm plates. Nodular brachiopod- and trepostome-rich packestones and grainstones are typical Rust lithology. However, a 2 m interval of tabular bedded wackestones to fossiliferous lime mudstones are present below the disturbed zone. These limestones and interbedded shales--a tongue of deeper water carbonates, approaching Dolgeville facies -- contain a distinctly different fossil fauna dominated by fenestrate and small ramose trepostome bryozoans, crinoids and the trilobites Isotelus and Ceraurus. These beds, probably correlative with the famed Rust Farm quarry beds of Walcott (1875a, b, c; 1876; 1881), contain abundant ceraurid trilobites at some localities. Brachiopods are much less common than in typical Rust strata. These tabular Rust strata include obrution deposits containing beautifully preserved specimens of Glyptocrinus and Ectenocrinus. These crinoids occur in both carbonate and siliciclastic mud tempestites/turbidites. Upright crinoid stems, up to 8 cn in length, attest to the severity of these sedimentation events.

STOP 2. Ninemile Creek, South Trenton
Disconformity (regional composite unconformity) capping Steuben Limestone and flooring Utica Shale.
At this stop, we will examine a composite unconformity -- the Thruway and Honey Hill discontinuities are superposed here -- which separates Trenton carbonates from overlying Utica strata. This is the only outcrop between Frenchville (15 km to the northwest) and the Norway-Middleville area (15 km to the southeast) where the contact between Trenton carbonates and overlying siliciclastics (in this case, the upper portion of the Utica Shale) can actually be seen; near Holland Patent (2 km to the northwest), a mineralized Steuben top surface can be seen on this same creek, but the basal 0.5 m of Utica Shale is poorly exposed. Suprisinigly, although the Holland Patent stream section is commonly cited, the South Trenton section is not mentioned in most earlier reports--most notably Kay, 1953.
The South Trenton section results from a broad anticlinal fold which brings the Steuben Limestone up into view for a distance of 100 m along this stream; this fold is exposed 500 m downstream (west) of the private road bridge over the creek. Three beds (totaling 0.75 m) of Steuben are exposed at the breached fold axis, and over 10 m of Utica Shale are exposed in the stop vicinity.
Dark gray packstone facies of the Steuben is overlain by a 35 cm-thick interval of very dark gray bioturbated wackestone, rich in phosphatic nodules and small rod-like phosphatic bioclasts which forms the limestone bench above water on the creek bank. This is, in turn, overlain by a phosphate-cemented corrosion surface which is distinctly pitted and which contains infillings of Utica Shale and phosphatic debris in depressions between knobs and raised bosses. Locally, a 2 cm-thick micritic ledge is developed along the corrosion surface; it is distinctly perforated, roofing a horizontal crevice space which is filled with phosphatic lag debris. Note the complex pattern of burrow-infilling "let down" of lag debris into and under this uppermost Steuben carbonate bed. Resting on the mineralized surface is black laminated Utica Shale which yields the lower Upper Ordovician graptolite Climacograptus pygmaeus. At Stops 4, 5, and 6 (to the southeast), we will also view Utica Shale over the Thruway discontinuity, but in these latter sections, both the underlying carbonates and the overlying shales are distinctly older. At Frenchville (to the northwest), the Steuben carbonates are overlain by turbiditic siltstones and shales of the Frankfort Formation. In this respect, the South Trenton exposure offers a unique opportunity to see Utica Shale correlative with strata of the type section (Utica) in contact with underlying carbonates. Furthermore, these contact sections illustrate a pattern of northwestward overlap of black muds which continues from Canajoharie to near Toronto, Ontario: progressively younger siliciclastics disconformably overlie progressively younger carbonates (Lehmann and Brett, 1991a).
We interpret the contact displayed at this stop as a corrasional discontinuity produced by combined processes of corrosion and abrasion under conditions of sediment-starvation and dysoxic to anoxic bottom waters. Unconformities of this type typically underlie black shales in the Appalachian foreland basin; sediment-starvation, episodic impingement of deeper water current processes, carbonate undersaturation of bottom waters, and low pH conditions are all believed to contribute to the corrasion process (see Baird and Brett, 1990 for overview). Lag debris produced from the corrasion process consists of insoluble grains of pyrite, phosphate, and quartz. Middle and Upper Ordovician lags of this type are mainly composed of phosphatic nodules and bioclasts.

Pass Strumlock Road.
The furthest southeastern exposure of limestones of the Rust Member (Denley Limestone) occur along a small stream near this road.

STOP 3. Rathbun Brook: Key beds of the Medial Trenton succession.
We will examine bed succession from the top of the Poland Member, through a complete section of our informal Wolf Hollow division, to the lowest 3.5 meters of our Brayton Corners division. Above these strata is a 10 m-thick interval of concealed strata, which begins near the closed meat packing plant. This is one of the most critical and enigmatic sections with regard to the problems of southeastward disappearance of the upper Denley (Rust) strata, thickening of Dolgeville facies, and appearance of lower/middle Utica beds.
Kay's (1953) Poland- Russia boundary on this creek is difficult to locate, as it is on several other creeks; he describes 33 m of "Denmark" at this section of which approximately half is Poland Member (which we will not examine) and half is Russia. We designate the base of Kay's (1953) Russia Member (and our Wolf Hollow division) as the base of a prominent 0.2 m-thick bioturbated packstone layer, herein designated the North Gage Road bed, which holds up a small waterfall on this creek and which will also be seen at Stop 4. This bed is approximately 12.5 m above the top of the Sugar River Limestone.
Above the North Gage Road bed is a 3.5 m interval of thin bedded, tabular to slightly nodular calcilutite beds which is, in turn, succeeded by a thick interval of nodular to massive shaly wackestone and lime mudstone which displays only weak bedding at many levels. This 15 m succession is rich in steinkems of Geisenoceras, which are conspicuous on numerous bedding surfaces. Other common taxa include the trilobites Flexicalymene and Isotelus, the bryozoan Prasopora, and pelmatozoan debris. Two main zones of strongly nodular limestones in this interval are separated by more tabular-bedded calcilutites (Figures 2, 6); These intervals of nearly non-bedded Russia seem to correlate to two thinner massive intervals at City Brook (Stop 4) and correspond to times of sediment-starvation which produced a distinctive nodular, cephalopod-rich facies (cephalopodenkalk) that is thin (stratigraphically condensed) relative to correlative deposits.
Upstream from North Gage Road, nodular deposits give way to tabular bedded calcisiltites and calcarenites which display sharp bases, some with sole marks. This 3.5 m succession, best developed near the fork in the creek below the abandoned meat packing plant, is also characterized by nodular to sandy phosphorite concentrations both at its base and at higher levels. At its base is an irregular knobby contact overlain by a bioclastic debris layer yielding a profusion of nautiloid steinkems as well as abundant phosphatic grains; this bed, in turn, is succeeded by a grainstone layer. This contact marks a submarine erosion surface that correlates to a corrasion surface at City Brook that Kay (1953) designated as the Poland-Russia boundary on that creek (Figure 3).
Herein, the strata between the top of the North Gage Road bed and the base of the 3.5 m thick calcislitite/calcarenite interval are informally refered to as the Wolf Hollow division of the Russia Member (for the excellent exposure of strata which we will see at that creek), and the overlying 3.5 m interval is refered to as the Brayton Corners division. The Wolf Hollow beds are lithologically distinct and are roughly correlative with the lower 3/4 of Kay's (1953) Russia Member (Figures 2, 6, 7).
The phosphate-bearing, grainstone-rich interval (Brayton Corners division) capping the Wolf Hollow seen here is apparently the upslope facies equivalent of ribbon limestone deposits (upper Dolgeville tongue) which we will see at City Brook (Stop 4). The Brayton Corners division expands upslope to 6 or 7 m of tabular-bedded mixed grainstone-calcilutite facies at Trenton Falls and near Gravesville. In that region, the grainstones are overlain by a 3-6 m interval of thin calcilutites which we refer to as the High Falls Tongue of the Dolgeville Member and which consitute the uppermost Russia succession of Kay (1953). Thus, the Brayton Corners beds appear to be relatively condensed and grade to turbiditic ribbon carbonates (upper Dolgeville tongue) downslope and stratigraphically upwards (High Falls Tongue of the Dolgeville Member) (Figures 2, 6).
Above the critical 10 m covered interval is a 20 m-thick succession of lower/middle Utica black shale with widely spaced micritic beds yielding the graptolites Dicranograptus nicholsonii and C. typicallis. No Rust or Steuben lithology is observed. For a full discussion of the problematic southeastward disappearance of upper Trenton deposits as well as the southeastward appearance of thick Dolgeville and lower Utica divisions, the reader is referred to the text.

The City Brook bed caps the falls on the north side of the road.
The type section for the Rathbun Member of the Sugar River Limestone is exposed in the face of the falls.

Road forks; stay to the right.
The left fork leads to lower portion of the section-Little Falls Dolostone, Black River Group, and the lower Trenton Group--on Wolf Hollow Creek. However, the landowner for this stream section does not allow people on her property.

STOP 4. Wolf Hollow Creek (City Brook), Old City
Condensation of Medial Trenton strata.
We will walk up the creek from the bridge below the Amish farm to examine, in ascending order: the uppermost Sugar River Limestone (Rathbun Member) and the Poland Member, the Wolf Hollow division, and the upper tongue of the Dolgeville Member of the Denley Limestone.
The lowest strata which we will examine are the massive calcarenites of the Rathbun Member of the Sugar River Limestone. Note the large domal bryozoans, Prasopora, in the lowest strata of the Rathbun Member. The Rathbun calcarenites are dramatically overlain by the "Trocholites Bed" of Kay (1937), which is the base of the Poland Member. The Trocholites Bed is herein designated the City Brook bed for the excellent bedding exposures in this interval above the road crossing on this creek. The nautiloid Trocholites is not sufficiently common for that name to have much meaning, and an alternative bed name is advanced here. This unit is widespread, marking the base of the Poland Member from the Lowville area (Chenowith, 1952) to the vicinity of Kast Bridge south of Middleville. At Wolf Hollow Creek this bed is 0.7 m thick, and it is expressed as nodular, intensely bioturbated shaly wackestone-packstone facies which is extremely rich in orthoconic nautiloid and endocerid steinkerns as well as the trilobites Flexicalymene and Isotelus which are sometimes complete. A thin pelmatozoan packstone layer capping the condensed City Brook bed at this creek appears to be coextensive with a submarine discontinuity which oversteps the City Brook bed between the Kast Bridge area and Little Falls. This discontinuity may further correlate with a corrosion surface flooring the Canajoharie Shale at Canajoharie Creek and at a small stream southeast of Amsterdam.
Poland and Wolf Hollow deposits on this creek are represented by a stratigraphically condensed section which is much thinner than that developed at Rathbun Brook (Figures 2, 6). Again, at this section, the North Gage Road bed is identifiable as a 0.2 m compact, nodular limestone. This condensed interval is disconformably overlain by the sparsely fossiliferous ribbon carbonate facies of the Dolgeville Member of which only the lower 8 m are exposed at this section; we will see the top of the Dolgeville at Stops 5 and 6. Careful mapping of middle Trenton beds shows that the Poland-through-Wolf Hollow interval of the Trenton Falls section thins negligibly from approximately 32 m in that area to 31 m at Rathbun Brook; however this interval thins dramatically from Rathbun Brook to City Brook, where only 15 m of section is present. Most of this southeastward thinning occurs in the upper (Wolf Hollow division) part of the section (Figures 2, 6); 15 m of nodular, cephalopod-rich wackestone at Rathbun Brook thin to 5.5 m at the present locality. Within the Wolf Hollow division, the two zones of nodular facies at Rathbun Creek thin respectively to form two massive nodular ledges which cap waterfalls on Wolf Hollow Creek and are separated by only 0.8 m of tabular calcilutites (Dolgeville facies). These meter thick benches, rich in nautiloid steinkems and trilobite fragments, are an Ordovician expression of condensed cephalopodenkalk facies described from Devonian and younger systems (see Jenkyns, 1971; Tucker, 1973; Wendt and Aigner, 1985; Baird and Brett, 1986a, b).
Kay (1953) first reported the mineralized corrosion (discontinuity) surface which separates the upper nodular carbonate (Wolf Hollow division) from the overlying upper Dolgeville tongue. This conspicuous break, seen to best advantage upstream from our turnaround point, records a period of submarine erosion (and probably also carbonate dissolution) on the seafloor prior to deposition of Dolgeville sediment. The association of this break with condensed underlying facies is no surprise; extremely slow rates of sediment accumulation are often exceeded by rates of sediment removal by winnowing and dissolution. We saw this discontinuity in a more subtle development above the nodular interval at Rathbun Brook (Stop 3) where sediment-removal was apparently less severe. Still further west, at Trenton Falls, the top of the nodular interval is conformable with overlying beds. Preliminary study of sections between City Brook and Little Falls suggests that the condensed nodular beds are overstepped by this erosion surface towards the southeast such that some of the Wolf Hollow interval is missing in the latter area (Figures 2, 6, 7).
Kay (1953) correlated his Poland-Russia boundary at Rathbun Brook (near our North Gage Road bed position on that creek) with the corrosion surface level on City Brook. This resulted in the "abrupt facies change" of nodular Russia to Dolgeville between the two sections. Our recognition of the North Gage Road bed on Wolf Hollow Creek as well as successful matching of the nodular condensed limestone intervals (Figures 2, 6) provides a more palatable stratigraphic match between these sections, and it eliminates the disjunctive facies change. On Wolf Hollow Creek, the Poland interval, herein redefined, encompasses a 9.5 m thick interval, dominated by tabular-to-wavy bedded micrite beds between the base of the City Brook bed and the base of the North Gage Road bed which caps a low waterfall on this creek. The Wolf Hollow division includes the remaining 5.5 m of Trenton section up to the discontinuity surface.
The overlying Dolgeville Member is composed of tabular bedded ribbon carbonate which alternates with very dark gray to essentially black shales. The Dolgeville strata yield a sparse fauna including graptolites and the small trilobites Flexicalymene and Triarthrus. We agree with other workers that this is a basin slope facies characterized by carbonate turbidites and an impoverished dysoxic fauna. Some beds show distinctive current markings (sole marks, ripple marks, and aligned fossils). Soft-sediment failure is represented by ball-and-pillow deformation at several levels.
The age of this Dolgeville sequence and its relationship to the Trenton Limestone is, in part, problematic (see text). The basal 1.5 m contains beds rich in nodular, sand-sized, phosphatic debris. This interval appears to be the downslope expression of the Brayton Corners division which we saw at Rathbun Brook and which also crops out at Trenton Falls (Figures 2, 6). However, higher, non-phosphatic Dolgeville deposits at Wolf Hollow Creek and near Middleville may correlate to the High Falls tongue of the Dolgeville at Trenton Falls and/or possibly to the Rust Member (see discussion in text).

Vuggy carbonates of the Little Falls Dolostone
Vuggy carbonates of the Little Falls Dolostone crop out on the left side of the road. Many of these vugs contain doubly-tenninated quartz crystal--the famed Herkimer Diamonds.

Note the "Ace of Diamonds" Herkimer Diamond quarry and campground.
We will pass another Herkimer Diamond quarry (Herkimer Development Corp.) over the next mile.

Cross West Canada Creek on Kast Bridge.

Cross North Creek.

Kay's Poland Mbr. of the Denley Limestone
Kay's Poland Mbr. of the Denley Limestone crops out along North Creek to the right.

STOP 5. Unnamed branch of North Creek, Eatonville
Upper Dolgeville-lower/middle Utica Shale contact.
We will proceed to the falls above the lower end of the creek section and examine the top 4 to 5 m of the Dolgeville Member, the Dolgeville-lower/middle Utica contact (Thruway discontinuity) and metabentonite (volcanic ash) layers in the lower/middle Utica.
Turbiditic, ribbon limestones of the Dolgeville are visible at the base of the falls and in the downstream bank. In the downstream bank, these beds are of a nearly uniform thickness and spacing, which is typical for large portions of the upper Dolgeville. A low diversity, dysaerobic fauna of graptolites, orthoconic nautiloids, and the trilobite Trianhrus is characteristic of these strata, though diminutive Onnielfa, Rafinesquina, and Flexicalymene can be found in winnowed hash layers in some parts of the Dolgeville. Just below the discontinuity, and extending up to it, is a zone of folded and contorted Dolgeville beds. (Use caution as you ascend the falls; these beds can be slick!) This disturbed zone is seen to better advantage on the New York State Thruway and it is discussed under Stop 6.
The Dolgeville-Utica discontinuity is slightly undulatory here due to effects of differential compaction over beveled limestone beds, and/or, secondary diagenesis along the contact. A lag zone of phosphatic hash overlies this break with subsidiary phosphatic debris layers recurring through the next 10 m of section. Phosphatic debris includes orbiculoid fragments, phosphatic rod-like structures possibly belonging to Sphenothallus, diminutive Onniella, corroded pelmatozoan grains, and comminuted graptolites. On the Thruway and in sections near Middleville and Norway, a spectacular lag of imbricated, corroded ribbon limestone fragments is present on this contact. These clasts display pitted exteriors characteristic of dissolution; partly exhumed in situ limestone beds at the section northeast of Norway display interior crack systems which have been extended and widened by this same process, allowing lag debris to work its way into the cracks.
The lower/middle Utica Shale consists of very hard, laminated shale with thin ribbon limestones and metabentonite layers. Graptolites are common and are spectacularly current-aligned on several bedding planes. Two excellent metabentonites can be examined in the falls; these beds appear as pasty, pale gray layers. New "fingerprinting" techniques, which allow identification of specific ash beds (specific eruption events) as geochemically unique, are presently being applied to these layers in still another approach to working out Trenton-Utica stratigraphy.
The Utica Shale at this section is distinctly older than that observed at Stop 2; the upper beds of this lower/middle Utica strata yield the graptolites Climacograptus typicalis and Dicranograptus nicholsonii whereas the upper Utica Shale at South Trenton contains C. pygmaeus, a distinctly younger graptolite (Kay, 1953; Riva, 1969). This change reflects, in part, the northwestward overlap (termination) of progressively younger Utica beds against the discontinuity surface in that direction. It also reflects the additive merging of the Thruway discontinuity with the younger Honey Hill discontinuity due to erosional overstep (see text: Figures 2, 6, 7).
As indicated earlier, the age of the upper Dolgeville, seen at this section, and at Stops 4, 6, and 7, is problematical with respect to the Trenton Limestone. The lower pan of Dolgeville (perhaps 10 to 13 m) and lower Canajoharie strata can be matched with the Poland Member using graptolites (Kay, 1953). However, the >22 m-thick upper Dolgeville tongue of the Norway-Kast Bridge area clearly overlies the top- Wolf Hollow corrosion surface, hence it cannot be linked with anything older than the Brayton Corners division at Trenton Falls. The great thickness of upper Dolgeville (and upper Canajoharie) strata relative to the upper Russia interval at Trenton Falls and at Gravesville opens the possibility that the upper Dolgeville may be time-equivalent with the Rust Member. This hypothesis remains to be tested.

Cross the mighty Mohawk River.

Thick bedded Dolgeville carbonates crop out on the right (south) side of the highway.

Low outcrops showing Dolgeville and lower/middle Utica strata
Low outcrops showing Dolgeville and lower/middle Utica strata are on the right (south) side of the highway.

Optional STOP 6A. New York Thruway: The Thruway discontinuity
This (along with optional Stops 6B and 6C) will be a relatively brief stop owing to hazardous traffic. We will stay in vehicles and observe outcrop features from van windows. This outcrop exposes essentially the same section as at Stop 5. However, this roadcut is cleaner, more extensive, and much more dramatic. Only the upper succession of Dolgeville strata is visible at this locality. Note that the upper Dolgeville contains densely packed beds of calcilutite and calcisiltite. In this region, top Dolgeville strata are underlain by a middle, shale-rich Dolgeville interval which contains relatively few ribbon carbonate beds. This middle Dolgeville interval, in turn is underlain by a calcilutite-rich lower Dolgeville succession which correlates with the Poland Member and the lower part of the Wolf Hollow division; the base of the Dolgeville however, is quite shaley. This "double paired" pattern of shaley strata giving way to more calcareous strata continues east to the Canajoharie region. On Rat Creek for example, the uppermost Canajoharie Shale is actually a Dolgeville lithology and contains closely spaced ribbon carbonate beds.
Most notable in this roadcut are the numerous folds which are best developed in the top 1.5 m of the Dolgeville. This zone of deformed strata can now be traced for at least 20 km from a small creek northeast of Norway to Nowadaga Creek (north of Newville). Lower Dolgeville beds are also locally deformed, as can be seen on the Thruway approximately 2 km west of Stop 6, but the highest deformed zone is the most conspicuous and persistent.
The cause and timing of this folding is controversial, and it is central to hypotheses concerning the inferred sequence of events associated with the Taconic Orogeny. Fisher (1979) noted that axial planes of these slump folds typically dipped to the east, indicating a down-to-the-west paleoslope, and postulated that the paleoslope reversal was the result of compressional up buckling of the Adirondack Arch. Work by Bradley and Kidd (1991) outlining the dynamics of this sort of "flexural extension" largely supports this interpretation. Clearly, a number of features indicate that this deformation is the result of post-depositional slumping. Firstly, although most deformation is ductile, fracturing and brecciation does occur in the deformed zone. Furthermore, even ductily deformed strata contain wedge-shaped fractures suggesting that this sediment was partly lithified. Secondly, most folds incorporate numerous beds.
At West Crum Creek, 5 km to the east of Little Falls, slump features indicate a more complex scenario. At that locality, most slump features indicate a northeastern dipping paleoslope; however, some folds indicate slumping towards the southwest. Perhaps these slump features represent a number of episodes of fault block adjustment. Similarly, directions of fold axes tend to be polydirectional at Nowadaga Creek, suggesting the possibility of muliple deformation events.
Above the folded beds is a sharp horizontal contact marking the change to lower Utica deposits. As we saw at Stop 5 and will see at Stop 7, this is an erosional discontinuity marked by reworked phosphatic lag debris, disseminated pyroclastic material, and localized concentrations of variably corroded, reworked Dolgeville limestone intraclasts. Furthermore, the uppermost micritic ribbons of the Dolgeville are coated by a pyritic crust Because the contact between the Dolgeville and the lower/middle Utica is so well exposed at this locality, we refer to this contact as the "Thruway discontinuity."
The Thruway discontinuity appears to breach many of the underlying folds such that many of the anticlines are "bald headed" structures. This indicates that post-Dolgeville, pre-Utica submarine erosion would have occurred after the folding event. Since we envision the episode of erosion as having taken place during a period of relative sea-level rise and consequent sediment starvation to the region, it is interesting to speculate that the folding event may have been a seismic harbinger of tectonic deepening of the basin. Again, we must note that the relationship of the fold horizon to the upper Trenton Limestone of the Poland-Prospect region is problematic; these folds may link to one the deformed zones in the Rust Member or to Brayton Corners strata (see text, Stop 1).

Optional STOP 6B. New York Thruway: Lower/middle Utica strata.
Along this portion of the roadcut, the lower/middle Utica Shale, which overlies the Dolgeville, is well exposed. As noted at Stop 6A, the contact between the Utica Shale and underlying Dolgeville strata is unconformable. Note, the metabentonite which forms a prominent rusty recession in the outcrop approximately 1.75 m above the base of the Utica. This particular metabentonite was seen at Stop 5 and will be seen at Stop 7. Other thin metabentonites can be seen in this roadcut and also in the "Black Canyon" (Stop 6C). Qualitatively, we have noticed that metabentonites typically are present in condensed intervals.
Also note that the lower/middle Utica strata in this outcrop contains thin, rusty (pyritic?), calcilutites. Locally, the lower/middle Utica succession between the Thruway discontinuity and the Honey Hill discontinuity is crudely divisible into three lithostratigraphic successions: 1) a lower, calcilutite-rich interval, 2) a middle calcilutite-poor, black shale interval, and 3) an upper calctlutite-rich interval.
Finally, note that this outcrop contains numerous small faults. These faults which displace both Dolgeville and overlying Utica strata belong to the Little Falls fault zone. The major fault of this fault zone, the Little Falls fault(> 1 km to the southeast), has a vertical displacement of 155 m (Bradley and Kidd, 1991).

Optional STOP 6C. Little Falls exit, New York Thruway
Utica strata of the "Black Canyon"
As we drive through the "Black Canyon," note the apparently monotonous nature of the Utica black shales. A number of thin metabentonites (which form rusty recessions in the outcrop) are present at this locality. The metabentonites along with graptolite zonation offer key -- yet sometimes controversial -- stratigraphic information for regional correlation of Utica strata (see Cisne and Rabe, 1978; Mitchell and Goldman, 1991).

Drive through the graffiti-enhanced canyon of Precambrain Grenville basement.

STOP 7. East Canada Creek, Dolgeville
Drag-folded Dolgeville and Utica strata.
Along East Canada Creek, below the Dolgeville Dam, the upper 15 m of Dolgeville strata and a large thickness of the overlying shales of the lower/middle Utica are spectacularly exposed in a drag fold along the east side of the creek. This drag fold is associated with the Dolgeville Fault, another of the syntectonic normal faults of the Mohawk Valley region.
Many of the features discussed and seen at Stops 5 and 6 are also readily examined at this outcrop:
1) The upper Dolgeville strata are slump-folded, but, due to the drag folding process, slump folding is not as evident as at Stop 6.
2) The Dolgeville strata are overlain by a 5 cm-thick phosphatic lag which we will sample if the stream level is low.
3) A metabentonite fonns a prominent recession in the outcrop approximately 1.5 m above the Dolgeville-Utica contact
4) The lower/middle Utica contains rusty-weathering calcilutites. However, calcilutite beds are less numerous than in lowermost Utica strata at Stop 5. This may be due to distance from a carbonate source, proximity to a siliciclastic source, and accommodation space (subsidence). Alternatively, we may be seeing a slightly lower stratigraphic interval at Dolgeville which is not represented at Stop 5 or is represented by condensed facies in that area.
Well developed fine-grained turbidites CTbcd) are present in the Utica. Winnowed shell lags containing trilobite hash, small brachiopods, and current-aligned graptolites within black shales, however, indicate that not all downslope-directed currents resulted in deposition.

A2: NON-FOSSILIFEROUS AND FOSSIL RICH BEDS IN THE HAMILTON GROUP; INDICATORS OF SEDIMENTATION RATES
David Linsley
Department of Earth and Planetary Science
University of Pittsburgh.
Pittsburgh, PA 15260
Stephanie Christensen, Leah Kittredge, Cathryn Dwyer, and Robert M. Linsley
Department of Geology
Colgate University
Hamilton. NY 13346
The Hamilton Group siliciclastic rocks are part of the progradational sequence formed at the onset of the Acadian Orogeny. Mountain building occurred to the east of New York state on a NNE/SSW trend. Paralleling the mountains to the west was the axis of the depositional basin which ran approximately through the Finger Lakes region. This is reflected by the thickening trend of Hamilton Group rocks from west (100 m) to east (1000 m). Throughout most of the Givetian Stage, eastern New York was close to the depositional source. This can be seen in the Albany area and immediately to the south where Hamilton Group equivalent rocks such as the Plattekill and Manorkill Formations preserve evidence of fluvial depositional environments (Willis 1990). To the west of the fluvial facies is the Panther Mountain Formation which contains nearshore marine sandstones which extend to the Unadilla valley area. The Panther Mountain Formation is the eastern equivalent of the Skaneateles and Ludlowville Formations of Central New York. In western New York the Hamilton group is predominantly dark shales and siltstones with rare carbonate units. The dark shales represent environments distant from the depositional source and in deeper water conditions than the sandstones of the Panther Mountain Formation. The rocks of central New York are a mixing and interfingering of the basinal and nearshore marine environments (Fig 1 ).

A2: NON-FOSSILIFEROUS AND FOSSIL RICH BEDS IN THE HAMILTON GROUP; INDICATORS OF SEDIMENTATION RATES

STOP 1. Hoaxie Road Quarry
This coarsening cycle is interpreted to be at the base of the Butternut Member in the Skaneateles Formation. The quarry exhibits the repeated coarsening-upward trend observed at most localities in the Hamilton Group. The rock type at the base of the quarry is shale interlaminated or thinly interbedded with fine siltstone. Close inspection reveals repeated 1-2 cm thick couplets of fine siltstone and shale. The siltstone contains low angle cross laminae and planar laminae. The base of the siltstone units is abrupt and the contact with the shale above is gradational. In the middle part of the exposure the silt beds become thicker (5 cm) and preserve rare articulated crinoid columnals typically on the upper surface of the siltstone beds. No fossil lag deposits are observed at the base of the siltstone beds and fossils are otherwise rare in this part of the outcrop. The upward increase in thickness of the siltstone beds indicates a closer proximity to the source of sediment and an increase in energy conditions on the substrate, both of which reflect the shallowing upward nature of the depositional cycles. The upper part of the outcrop is bioturbated very fine sandstone and contains a normal Hamilton assemblage of bivalves and brachiopods.
Fossils in the lower part of the exposure are rare and when observed are concentrated on single bedding planes. At vertical intervals of 1-2 m discontinuous lenses, meters in width and 1-2 cm in height, contain articulated bivalves, brachiopods, and the crinoids Gilbertsocrinus and Acanthocrinus. The bivalves Leiopteria conradi, Actinodesma erectum and Actinopteria boydi are numerically the most abundant taxa and are all epifaunal, possibly byssally attached forms. The brachiopods Tropidoleptus carinatus and Camarotoechia congregata are associated with the bivalves but are less abundant. The crinoids are articulated and appear to be using the bivalve shells as a substrate. The unusual aspect of these shell beds is that they are not storm accumulations and the fossils are articulated and in life position. Rocks above and below the fossil beds are nearly barren and preserve only rare brachiopods and bivalves.
The presence of small-scale sedimentary structures in fine grained sediments is rare in Hamilton Group rocks in central New York. Infaunal and semi-infaunal organisms disturb the substrate and destroy sedimentary structures. If sedimentation rates are low enough for the organisms to continually rework the sediment, no sedimentary structures will be preserved and the mud and silt layers are homogenized into the bioturbated mudstone commonly observed in Hamilton Group rocks. At this and other localities there is a conspicuous absence of fossils associated with the stratigraphic intervals where sedimentary structures are preserved. An absence of fossils may be explained by rapid deposition rates which create an unstable substrate, by a lack of oxygen, or by non-normal marine salinities. The pycnocline model is applicable in relatively deep water settings; however central New York is closer to the depositional source and in presumably shallow water depths.
An alternate explanation for non-fossiliferous units could be viewed as follows: assuming that the depositional cycles are shallowing up sequences one method of deposition may have been basinal infilling. If sea level is stable and sediment is transported to the basin, progradation of the shoreline will occur. The part of the basin proximal to the shoreline will become infilled with sediment and a shallowing upward depositional sequence will be produced. By this model the muddy siltstones would be less than ten meters below the sandstones. The water depth of the sandstones is equivocal but they are definitely within storm wave base, and given the proximity to the shoreline, probably in less than ten meters water depth.
Brett (1985) has postulated that periods of maximum deposition occur in the middle of the depositional cycles in the siltstone/ mudstones and that while the sandstones are deposited in the shallowest water, they are also periods of low deposition rates. The sandstones are possibly reworked or winnowed over long periods of time. If the siltstones and shales were deposited rapidly this could have created unstable water saturated sediment which would have kept epifaunal or semi-infaunal filter feeders from colonizing the substrate, thus creating non-fossiliferous intervals. However evidence from this locality suggests otherwise due to the presence of rare shell beds with epifaunal bivalves. Furthermore, the centimeter- scale siltstone beds, which should have been a relatively stable substrate, have no fossils associated with the upper surface. This suggests that a factor other than anoxia or substrate instability was preventing the colonization of the substrate by epifaunal benthic organisms.
The proximity of central New York to the fluvial environments in the east suggests that hyposaline conditions could be a factor in controlling faunal assemblages on the nearshore shelf. The northern end of the Appalachian Basin during the Devonian was a relatively enclosed basin. The uplands created to the east by the Acadian Orogeny were the major source of siliciclastic sediment. Fluvial depositional systems have been identified in Hamilton Group equivalent rocks in eastern New York. Rivers feeding the sediment to the basin may have had the effect of reducing salinity in the shallow, nearshore regions of the basin. If the siltstone/ mudstone intervals were deposited during periods of maximum sedimentary influx, and the position of the ancient shoreline was less than 100 km to the east, it is possible that the nearshore or shallow part of the basin experienced periods of hyposalinity. During periods of low rainfall normal salinities would return to the nearshore part of the shelf and a normal marine fauna would colonize the substrate. If the sandstones were deposited or reworked during periods of low sedimentary influx this may also have been a time of relatively low rainfall and consequently normal marine salinities.
Fossil evidence in the form of thin lenticular shell beds containing in place articulated bivalves and crinoids suggests episodic colonization of the substrate followed by an abrupt event which preserved the fossils without disruption. The rare fossils, typically Camarotoechia congregata, Trooidoleptus carinatus, Grammysia bisulcata and Pterochaenia fragilis in the intervening layers between shell beds are found on single bedding planes with only Grammysia appearing to be in life position. In the middle part of the outcrop siltstone beds preserve articulated crinoids on the upper surface of the beds. The fossils between the shell beds in the interbedded siltstones and shales are the best indicators of the typical paleoenvironment. Fossils such as Camarotoechia, Tropidoleptus and Grammysia could have been salinity tolerant. Only Grammysia and Pterochaenia are found articulated and in place. The brachiopods could have been transported although they are not found associated with sedimentary lag deposits. The crinoids associated with siltstone layers could have been transported, although not over long distances since they are still articulated. The shell beds contain dominantly bivalves which may have been salinity tolerant (Brower and Osborne 1991) but also contain articulated crinoids which are much less likely to have been salinity tolerant.
The rarity of both fossils and bioturbation in the thinly interbedded siltstones and shales suggests that some factor was preventing colonization of the substrate. Dysoxia has been suggested as a possible factor but the fossils that are present tend to be salinity tolerant species rather than species typical of the deeper water dark shales associated with dysaerobic conditions. When periods of normal marine conditions occur the substrate is apparently rapidly colonized by bivalves, brachiopods and crinoids. These brief periods of colonization are equally rapidly ended by an event which preserves the fauna intact and articulated. The proximity of central New York to the ancient shoreline and accompanying river systems suggests that fresh water flooding of the nearshore shelf may account for some nonfossiliferous intervals in the interbedded silts and shales.

STOP 2: Brookfield West Quarry
This section is tentatively placed as the fourth or uppermost coarsening cycle of the Delphi Station member of the Skaneateles Formation. The lower two meters of section contain 5-20 cm thick interbeds of shale and siltstone. Siltstone beds have an abrupt base and grade upward from planar laminae into small scale, high angle cross laminae. The upper surfaces of some siltstone beds preserve symmetrical ripples. The siltstone units are interpreted to be event beds, probably storm deposits. The absence of infaunal and epifaunal organisms with the related bioturbation is discussed in the section on the Hoxie Road quarry. The shale separating the siltstones is fissile, lacks lamination and contains no fossils with the exception of rare cephalopods.
In the middle of the exposure is a noticable notch in the quarry wall. Above this the siltstone/ shale interbeds disappear and bioturbated sandstone, with a normal Hamilton faunal assemblage of epifaunal bivalves and brachiopods, is observed. The notch in the quarry wall is a light gray clay, varies in thickness from 0.5-3.0 cm, and is tracable the length of the outcrop. X-ray analysis reveals the presence of illite and chlorite but no expandable clay minerals. The coarse fraction of the clay does contain some euhedral crystals. This bed is tentatively identified as a meta-bentonite .
Ten centimeters below the clay bed is a densly packed fossil-rich zone 1-4 cm thick. This is the first appearence of fossils in the lower part of the quarry. The assemblage is unusual in that it contains the monoplacophoran Cyrtonella and abundant infaunal bivalves, Nuculoidea, Nuculites and Modiella. Infaunal bivalves would not normally be found in a packed shell bed like this since when they die they are already buried. The presence of these shells together indicates that the sediment has been reworked and that this bed may be a sediment-starved omission surface. Phosphate pebbles are found with the shells in this bed which also suggests that the accumulation of shells took place during a depositional hiatus.
This section is somewhat unusual in that it does not follow the typical pattern of a gradual coarsening upward trend. The fossil rich sandstones at the top of the locality appear relatively abruptly following the appearance of the clay bed. Whether there is a tectonic connection between the two events is highly ambiguous.

STOP 3: Bailey Road Quarry
The seventeen meters of section at this locality represent the Pompey Member of the Skaneateles Formation. From the base of the section to the top there is an overall coarsening trend from shale through fine sandstone. Within this coarsening trend there are four, meter-scale coarsening upward units. In the terminology of Bush and Rollins (1984) the entire outcrop would be a fifth order cycle and the smaller coarsening sequences would be sixth order cycles. The base of the smaller cycles is indicated by topographically level areas within the quarry.
The lowest small-scale coarsening cycle is bioturbated shale with abundant, well preserved, articulated bivalves and brachiopods. The bivalve assemblage is dominated by Nuculites oblongata, N. triguiter, Modiella pygmaeaand Paracyclas Iicata. The top of the first cycle grades upward into a packed silty shell bed containing Longispina, Mucrospirifer, and rare septate rugose corals. The second depositional cycle grades upward from a siltstone through a coarse siltstone. The finer grained interval is bioturbated but contains no fossils with the exception of rare cephalopods. The coarser part of the cycle contains a chonetid/Mucrospirifer assemblage. The third cycle is progressively coarser than the first two, grading from mudstone through very fine sandstone. The base is again bioturbated but relatively non-fossiliferous. The top of the cycle is capped by a packed shell bed containing the brachiopod genera Rhipidomella, Pseudoatrypa and Athyris. These brachiopods, particularly Pseodoatrypa, are relatively rare in the rocks of central New York and have been interpreted to represent clear non-turbid water conditions. The fourth cycle is again coarser than the previous three, grading from siltstone to fine sandstone. Brachiopods dominate the fauna though bivalves, particularly Cypricardinea indenta, Paracyclas lirata and Nyassa arguta, are quite abundant. Bryozoa and zoophycus are common in the upper part of the cycle but appear only occasionally below this. Several packed shell beds are located within this cycle. Two are similar to the one capping the third cycle (i.e. dominated by Rhipidomella and Athyris) while several others are dominated by Spirifers and Ambocoelia, with lesser amounts of Chonetes and other organisms
The depositional sequences at this locality provide some clue to sedimentation rates if the assumption is made that fossil preservation potential and biogenic productivity, in terms of shell production, is constant through time. The fossiliferous shaley interval of the lowest cycle can be interpreted to have relatively low sedimentation rates due to the presence of numerous infaunal and epifaunal organisms. The shell bed which caps this interval is a period of low siliciclastic deposition where fossils accumulated gradually through time. Evidence in the form of disarticulated shells suggests that the shell bed was affected by storm events; however, no sedimentary structures are visible to support wholesale transport or reworking of the shells as a lag deposit. The base of the shell bed is gradational with the underlying shale, further supporting an in place formation of the bed. The base of the second cycle is nonfossiliferous yet it is bioturbated. This interval probably represents a period of rapid deposition where epifaunal filter feeders would have had difficulty with an unstable and rapidly aggrading substrate. The absense of infaunal deposit feeding bivalves cannot be easily explained since the presence of bioturbation and rare cephalopods suggests that organisms were present and that fossilization was possible. The upper part of the cycle is coarser grained and preserves abundant brachiopods. This indicates a decrease in sedimentation rates. The third cycle is again non-fossiliferous at the base and is capped by a shell bed containing an unusual assemblage of brachiopods. The Athyris/Pseudoatrypa/Rhioidomella assemblage has been interpreted to represent a shallow, clear water depositional environment. This shell bed represents an absence of siliciclastic deposition. The abundant brachiopods of the fourth cycle again suggest fairly low sedimentation rates, while the shell beds, similar to those of the third cycle, most likely represent periods of non-deposition.

STOP 4. Geer Road Quarry
The nine meters of section at this locality represent the lowermost of the four coarsening upward cycles in the Moscow Formation (Selleck, personal comm.). Grain size ranges from very fine siltstone at the base of the quarry through very fine sand at the top, with most of the coarsening occurring in the upper three meters. The faunal assemblage is dominated by brachiopods (80%) and bivalves (10%) with gastropods, cephalopods, trilobites, bryozoans and crinoids also present.
Fossils are distributed abundantly and fairly uniformly throughout the section; however, flat bedding planes of densely packed shells, predominantly of the brachiopod Chonetes, also occur. In the lower three meters of the section these Chonetes shell beds occur at intervals of 20-25 cm. Above the first three meters Chonetes beds become rare. Orientation of the shells varies between the upper and lower beds. In the lower shell beds Chonetes are found 50% in life position and 50% overturned while in the upper beds 90% of the Chonetes are overturned. In the siltstones between the shell beds different taxa are present in approximately the same ratio as seen on the shell beds, but the density of fossils is much less. No sedimentary structures are visible.
The Chonetes beds may represent storm events during which transported siliciclastic sediment smothered the brachiopods. However, the sedimentary characteristics normally associated with tempestites, such as fining upward sequences or planar or cross laminae, are not visible. The presence of fossils in the sediment between the shell beds suggests that they are not winnowed lag deposits.
A more probable theory is that the shell beds represent periods of non-deposition allowing for the build-up of many shells over time. If the coarsening upward sequence reflects shallowing, the lower shell beds would have been in deeper water than the upper beds. The differing orientations of the Chonetes may then be explained; the lower, deep-water shell beds would have remained relatively unaffected by wave action, allowing half of the brachiopod shells to remain, even after death, in the less stable life position. The Chonetes of the upper shell beds, being in shallower water, would have been 90% overturned into a hydrodynamically stable position.
The most definitive evidence for storm deposited sediments is a 5-8 cm fine to medium grained sand bed located six meters above the base of the quarry. The sand bed has an abrupt base and contains small scale cross and planar laminations. Both shelled fossils and trace fossils are absent from this bed, appearing neither as storm lag deposits nor as colonizers of the post-storm surface. The position of this bed is near the top of the section, in the coarser part of the cycle. Assuming that the cycles represent shallowing upward, this part of the quarry may have been within the influence of storm wave base. The lower, finer grained part of the cycle was likely deposited in deeper water below storm wave base.

STOP 5. English Avenue Quarry
This quarry is situated in the Delphi Station member of the Skaneateles Formation. The gastropod species Bembexia sulcomarginata is abundantly represented at this locality and all specimens are either of the ornamented variety or the intermediate B variety. (See the discussion of Bembexia following the locality 6 description.) They are distributed from the finer grained siltstones at the bottom of the quarry through the coarser material at the top.

STOP 6. Peterboro South (Swamp Road South)
This locality is in the lower part of the Pecksport Member of the Marcellus Formation. The rock type is mudstone with very few sedimentary structures and abundant fossils. The preservation at this locality is quite exceptional for the Hamilton Group in that molluscs have their shells intact and are not preserved as composite molds as at Geer Road. Small amounts of original aragonite may still be found in some shells and the replacement of aragonite by calcite is so fine that the original shell microstructure is still preserved (Carter 1978).
All the specimens of Bembexia sulcomarginata that have been found in this quarry are of the unornamented type. They may be found throughout the entire quarry but are most abundant in the upper surface of the lower quarry face.

STOP 6A. Peterboro North
(no description)

A3: COMPARATIVE SEDIMENTOLOGY OF THE LOWER DEVONIAN MANLIUS FORMATION NEAR HAMILTON, NEW YORK
Robert V. Demicco,
Tim K. Lowenstein,
Binghamton University
The State University of New York,
Binghamton, New York
Kathleen M. Browne
Comparative Sedimentology Laboratory
Rosenstiel School of Marine and Atmospheric Sciences
Miami, Florida
INTRODUCTION
The paleo-environments of ancient sedimentary deposits are diagnosed from the vertical and lateral distribution of elemental rock units (subfacies), characterized principally by their assemblages of sedimentary structures, using analogs established from observations of processes and the sediments in modem depositional environments (the "comparative sedimentology" method of Ginsburg, 1974). Modem shallow marine carbonate environments carry a particularly rich inventory of primary and early diagenetic sedimentary structures, such as current and wave bedforms, trough and tabular cross-stratification, "herring-bone" cross-stratification, flat lamination, wavy and crinkled lamination, thin bedding, stromatolites, thrombolites, mudcracks, sheet cracks, prism cracks, flat pebble gravels, fenestrae, burrows, evaporite minerals, early cements, hardgrounds, caliche crusts, tepee structures, soils, and so on. And most significantly, the stratigraphic record back at least into the Proterozoic is replete with carbonate deposits that delicately preserve these sedimentary structures (see, for example, Ginsburg, 1975; Wilson, 1975; Hardie and Shinn, 1986; Gretzinger, 1989), demonstrating the existence through much of geologic time of environments and environmental processes analogous to those of modem shallow marine carbonate platforms and shelves.
There are other areas of study beyond reconstruction of paleo-environments where the environmental information preserved in the primary sedimentary structures and early diagenetic features of shallow water carbonates is of considerable value, for example, in the fields of paleo-oceanography, paleo-climatology and cyclostratigraphy. In particular, tidal flat facies are unsurpassed "sea level gauges," "tide gauges," and "climate recorders" (Hardie, 1977, p.188-189). An unambiguous record of the position of ancient mean sea level is engraved within the intertidal subfacies of all ancient shallow marine carbonate deposits. And the same intertidal subfacies carry a record, quantitatively determinable, of the tidal range in the depositional environment (cf. Klein, 1971). At the same time, the subtidal subfacies record the ambient and storm wave energy levels across the buildup, and this information in turn reflects, at least in a qualitative way, the prevailing weather patterns. The nature of the supratidal subfacies is a direct response to the prevailing climate in the region (Hardie and Shinn, 1986). If the climate is arid, like the modem Persian Gulf carbonate environments, then the supratidal subfacies will carry evaporite and aeolian features (Shinn, 1983). If the climate is rainy, like the modem Andros Island tidal flats, then the supratidal deposits will carry freshwater marsh and lake features (Hardie, 1977; Shinn, 1983).
The stratigraphic record abounds with shallow water carbonate deposits characterized by meter-scale vertical successions of subfacies that are organized into shallowing-upward "cycles", as revealed by analysis of primary sedimentary structures and early diagenetic features (Wilson, 1975; James, 1984; Hardie and Shinn; 1986). Vertical stacks of such shallowing-upward cycles record repeated fluctuations in relative sea level. In some cases these sea level fluctuations appear to be periodic oscillations, driven by Milankovitch astronomical rhythms (e.g. Goldhammer and others, 1987, 1990). Clearly such cyclic shallow water carbonates take on a special significance as storehouses of information about global climatic and eustatic variations in the past.
Overall, an understanding of the origin and significance of primary sedimentary structures and early diagenetic features is vital in our quest to unravel the origin and significance of carbonate deposits in the geologic record. Without such an understanding at the individual sedimentary structure scale we cannot hope to accurately reconstruct the large scale accumulation history of carbonate buildups or to decipher the roles of sea level changes, sedimentation rates, subsidence rates, and tectonics in determining the facies stratigraphy, cyclostratigraphy and sequence stratigraphy of these buildups. In summary, it could be said that unless we get the little things right we may not be able get the big things right.
With this in mind, the purpose of this trip is to examine two or three sections of the Manlius Formation (Lower Devonian) near Hamilton, New York. We are principally concerned on this trip with describing the subfacies that comprise the Manlius Formation in this area. We shall then use the sedimentary features preserved in these rocks to interpret their depositional significance. Defining cycles of subfacies that record relative sea level changes in the Manlius Formation is a controversial matter. One need only compare: (1) Laporte's (1975) original ideas. about migrating tidal flat islands; (2) the shallowing-upwards cycle definitions of Kradyna (1992); and (3) the allocyclic stratigraphy of Anderson and Goodwin (1991). Literally every possible kind of cycle and interpretation of cycle significance have been suggested for this unit. It is not our intention to review this controversy. However, it is our contention that a thorough analysis of the primary and early diagenetic sedimentary structures that are so well preserved in this unit must be the starting point for any paleo-environmental analysis of these rocks including any analysis of their cyclostratigraphic significance. GEOLOGIC SETTING
The Manlius Formation is the lowermost unit of the Helderberg Group, a succession of Lower Devonain carbonates exposed across central and eastern New York. Rickard (1962) interpreted the Manlius Formation as time transgressive from east to west. Figure 1 is a portion of Rickard's (1962) stratigraphic chart of the outcrop belt of the Helderberg Group across central New York from Cherry Valley on the east to Syracuse on the west. Here the Manlius Formation is very nearly flat-lying and is divided into a number of members (Fig. 1).
DESCRIPTION OF MANLIUS SUBFACIES
Figures 2 and 3 are measured stratigraphic logs of the Manlius Formation from two stops of this fieldtrip: (1) Clockville and (2) the Jamesville Quarry (locations given in Figure 4). A third optional stop is the quarry at Munnsville. At these three locations the Manlius Formation can be divided into 6 subfacies defined by their assemblages of primary and diagenetic sedimentary structures: (1) grainstone subfacies; (2) microbial bioherm subfacies; (3) wavy to lenticular thin beddded subfacies; (4) laminite subfacies; (5) disrupted mudstone subfacies; and (6) thin beddite subfacies. These are described below.
A note on the significance of the colors of the rocks is in order. In outcrops in this part of the Appalachians the color of a well weathered surface is a fairly reliable guide to the mineralogy of the rock. Limestone (composed of low magnesium calcite) generally weathers blue or grayish blue. On the other hand, dolomite (CaC O3·MgCO3) commonly weathers a tannish yellow. Dolomite takes on this color upon weathering as most natural dolomites have small amounts of iron substituting for Mg. Upon weathering the iron oxidizes and stains the rock with iron oxide.
Grainstone Subfacies
The grainstone subfacies is composed of intraclastic, bioclastic, and peloidal grainstones and conglomerates. The grainstones are generally well sorted and individual sets vary from coarse to fine sand-sized. Intraclastic conglomerates have rounded clasts up to 20 mm in diameter. In two outcrops of the Manlius Formation we will examine, the main primary sedimentary structure of the grainstones and conglomerates is planar stratification. The sets of planar strata are tens of millimeters thick and are separated by dolomite-rich seams a few millimeters thick. Cross-stratified grainstones are rare in these two outcrops; one probably example is 4.5 m above the base of the Jamesville Quarry section.
Microbial Bioherm Subfacies
The microbial bioherm subfacies includes thrombolites and stromatolites found at the Clockville and Munnsville Quarry sections. The thrombolites of the Manlius Formation are described in Browne and Demicco (1987). Aitken (1967, p. 1164) proposed the term thrombolite: "(from the Greek thrombos, bloodclot) ... for cryptalgal structures related to stromatolites, but lacking lamination and characterized by a macroscopic clotted fabric." Other terms that are commonly used to refer to these and similar structures are "bioherm" and "biostrome" (e.g. thrombolitic bioherm or biostrome). The former term refers to discrete mound or coalesced mounds (interpreted to be of organic origin) embedded in rocks of a different lithology whereas a biostrome is a layer consisting of and built mainly by organisms. Manlius Formation thrombolites occur as discrete mounds, as coalesced mounds and as continuous biostromes. Figure 5 is a bedding diagram of a portion of the Clockville section illustrating the three layers that contain thrombolites. The basal layer (0 to 1 m) contains discrete mounds up to 1 m thick and coalesced mounds where laterally adjacent thrombolites have welded upon upward growth. The thrombolites in the bottom layer are surrounded by planar-stratified grainstones. The upper most layer at Clockville (3.8 to 5 m above the base) is a biostrome. Irregularly- shaped pockets of grainstone and intraclastic conglomerate are found within this layer. The middle layer of thrombolites between 2.9 and 3.8 m is an interesting and complicated one. The lowermost 200 mm of this layer is a continuous thrombolite biostrome with stromatolites nucleated on its upper surface. Higher up in the layer are scattered, discrete, delicate thrombolites composed of upward-directed fingers of mudstone. These also are capped with stromatolites. All of the stromatolites in this layer have "gravity defying" mudstone laminae. However, surrounding the gravity defying laminae are wavy laminae of fine peloidal sand that are quite different. These wavy laminae are part of the wavy and lenticular thin bedded subfacies and are more fully described below.
The internal structures of thrombolites of the Manlius Formation at the hand-sample scale are complicated. Structures are visible in sawn slabs and in those outcrops which have been delicately etched by selective weathering. Internally, Manlius Formation thombolites comprise millimeter- to centimeter-scale mudstone masses ("clots" or "mesoclots") surrounded by skeletal mudstones, skeletal wackestones, skeletal packstones, or rare sparry patches. The mudstone masses typically make up 30 to 50 % of the rock and vary from highly irregular shaped to vertically-oriented columns with circular cross-sections in bedding plane views. Columns can branch upward. There are two types of thrombolites at the Clockville section: (1) those found between 0-1 m, 2.8-3 m, and 3.75-5 m above the base; and those found at 3.5 m above the base.
Mudstone masses in the thrombolites found between 0-1 m, 2.8-3 m, and 3.75-5 m above the base at Clockville are made up of 5 components: (1) millimeter-scale hemispheroids with radial and concentric structure which Browne (1986) interpreted as the problematic fossil Keega; (2) variable amounts of the problematic fossil Renalcis and masses of micrite that superficially resemble this form; (3) stromatolitic mudstone laminae; (4) peloidal laminae with micron-diameter filament molds; (5) rare, submillimeter-scale brachiopod, ostracod and gastropod fragments. In some cases Browne (1986) reported possible framework-building skeletal red algae encrusting the sides of mudstone clots. Structureless skeletal mudstones, wackestones and packstones that are lighter in color fill the spaces between the mudstone masses. Millimeter-scale burrow-tubes filled with peloids disrupt the fills among thrombolitic mudstone clots and fingers but do not cross-cut them.
The thrombolites in the layer at approximately 3.5 m differ from other Manlius Formation thrombolites insofar as the digitate fingers that make up these thrombolites are dense mudstone and they do not contain microfossils. Also, the fingers of these thrombolites are surrounded by mudstone with no skeletal fragments. Finally, the thrombolite mounds themselves (and the ones immediately below) are capped by stromatolites and surrounded by a unique subfacies: the wavy to lenticular thin bedded subfacies described below.
Wavy to Lenticular Thin Bedded Subfacies
The wavy to lenticular thin bedded subfacies is only found in the outcrops of this field trip surrounding thrombolites and stromatolites 3.5 m above the base of the Clockville section. The rocks comprise dolomite fine-grainstones alternating with dolomite mudstones. Mudcracks are rare. The grainstones have flat bottoms and wavy tops. The wavy tops of the grainstone layers appear to be oblique cuts through wave ripples and, indeed, internally the grainstone layers are sets of wavy fine lamination typical of oblique cuts through wave ripples (see de Raaf and others, 1975). The mudstone layers also are sets of fine wavy laminae. These mudstone layers drape the ripple-marked surfaces of the grainstones, thinning over crests and thickening
The geometry of the limestone layers and sets varies from planar and continuous through discontinuous lenses to notably wavy and nodular forms similar to "nodular", "irregular", "flaser", and "lumpy bedding" described by Wilson (1975), Wilson and Jordan (1983), Matter (1967), and Schwarz (1975), among others. At the lateral boundaries of the nodules, internal graded layers within the limestone patches thin by compaction and pass laterally into dolomitic shaley partings. Other volume reduction features are very common in these rocks, especially in the mudstones and wackestones. Stromatoporoids and corals of various scales are common in the thin beddite subfacies of the Manlius Formation. In many cases, these rigid skeletons are encased in dolomitic shaley seams which bend around the skeleton from both above and below (drag or penetration effects of Pray, 1960). The affected seams thin laterally directly above and below the bioherm and show increasing dips and thicknesses down the sides of the skeleton. Significantly, seams are thickest along the flanks of the skeleton and thin not only over and under the bioherm but laterally away from the bioherm as well. It is important to note that nodules of mudstone show the same drag effects of shaley dolomitic seams around them just as the stromatoporoids and corals do. This, in turn, suggests that the limestone nodules were hard at the time of compaction as well.
COMPARATIVE SEDIMENTOLOGIC INTERPRETATIONS
By far the easiest rocks to interpret are the laminites. The crinkled geometry of many of the laminae; a number of which are clearly composed of detrital fine-sand and silt-sized peloids, suggests that sediment laminae were agglutinated by a sticky microbial mat. The desiccation cracks suggest periodic exposure. Moreover, the prism-cracks imply the periodic rise and fall of a ground-water table (Ginsburg, 1991, pers. comm.), and drying out in the vadose zone. Modem analogs of this subfacies are found beneath high intertidal to supratidal subenvironments of low-energy tidal flats where there is an organic mat dominantly composed of cyanobacteria ("blue-green algae"). Modem examples of laminated sedimentary deposits directly influenced by a surface mat of cyanobacteria have been described from : (1) the supratidal islands of Florida Bay (Ginsburg and others, 1954); (2) the intertidal and supratidal mud flats and coastal marshes of Andros Island by Black (1933), Monty (1967, 1972, 1976), Monty and Hardie (1976), and Hardie and Ginsburg (1977); (3) the intertidal and supratidal mud flats of the Trucial Coast of the Persian Gulf by Kendall and Skipwith (1968) and Kinsman and Park (1976); (4) the intertidal sand and mud flats of Shark Bay in Western Australia (Davies, 1970; Logan and others, 1974) and (5) the siliciclastic mud flats accumulating behind barrier islands of the Delmarva Peninsula, Virginia, by Harrison (1971). Subaerial desiccation of thick fleshy surface mats results in disruption into polygonal cracks (e.g. Kinsman and Park, 1976) the upturned edges of which become preferential sites for growth of the succeeding generation of cyanobacteria to produce oversteepened "stromatolitic" layering (e.g. the type C algal heads of Black, 1933). The anticlinal tepee-like buckles of the laminite 4.3 m above the base of the Jamesville Quarry section have two possible origins. Lateral expansive growths of cyanobacterial mats can produce buckles in soft sediment (see Figure SA and 8B, p. 178, in Shinn, 1983). Alternatively, expansive growth of cements within crusts forming in the high intertidal to supratidal zone can produce anticlinal buckles where crusts overthrust and break.
The laminite subfacies of the Manlius Formation records deposition on a tidal flat. However, it should be noted that "tidal" is used in a rather loose way. The periodic introduction of sediment onto most of the modem examples cited above is by storms. Indeed, for many modern tidal flats, the normal tidal process is to inundate the cyanobacterial mats with clear water. Many modern examples are more properly called wind tidal flats insofar as the prevailing wind direction can have as much, if not more, to do with the flooding of the flats as the tides do.
The disrupted mudstone subfacies also has a quite elegant modern analog: the mudcracked soils developing on modern playas in closed basins and supratidal flats (Smoot, 1983; Smoot and Katz, 1982; and Smoot and Lowenstein, 1991). These modern playa muds are riddled with mudcracks of various sizes and spacings that are open at the surface but at depth are filled with mud, muddy sand, or sand. Mudcracks branch and connect via a complicated network of sheet cracks that surround irregularly-shaped patches of finer mud. Within these modern muds are irregularly shaped fenestrae that are the result of entrapped air bubbles and desiccation. Typically, laminated Pleistocene lake clays grade up through a brecciated zone into a chaotic mud disrupted by complex, superimposed mudcracks. This sequence strongly resembles the smaller cycles that comprise the disrupted mudstone subfacies. It is interesting to speculate as to the time value of each of the small cycles in this subfacies because Holocene/Pleistocene examples may record thousands of years of slow aggradation and intense disruption by desiccation.
The thrombolites of the Manlius Formation are similar to their more common Cambrian and Lower Ordovician counterparts and are similarly interpreted as small, in-place mounds that were hard, rigid bioherms with a biogenic framework when deposited; in other words, they were biological reefs. The clotted mudstone that makes up Manlius Formation thrombolitic fingers is interpreted as calcified cyanobacterial filaments similar to Girvanella. The problematic microfossil Renalcis is generally interpreted as calcified coccoid cyanobacteria or an encrusting foraminiferae. The enigmatic micrite clots that give thrombolites their name have also been interpreted to be the result of calcification of cyanobacterial mats and colonies.
Oddly enough, thrombolites of the Paleozoic resemble in some respects porous carbonate mounds that were deposited in Pleistocene and Holocene pluvial lakes collectively known as tufa. Pleistocene to Modern lacustrine tufas comprise mounds and coalesced mounds that make large encrustations up to 30 m high. Internally, lacustrine tufas may be composed of: (1) rigid centimeter-scale clots and fingers composed of micrite that strongly resemble Renalcis, Girvanella, etc.; (2) stromatolitic laminae and small stromatolites; and (3) dendritic masses and arborescent millimeter- to centimeter-scale "shrubs" interpreted by Chafetz and Folk (1984) to be calcified bacterial colonies. Surrounding these framework elements in lacustrine tufas are a variety of detrital sediments, many of which show evidence of penecontemporaneous cementation.
The wavy to lenticular thin bedded subfacies surrounds thrombolites and stromatolites 3.0-3.75 m above the base of the Clockville section. We are not sure of the origin of this subfacies and critical to any interpretation is whether these rocks are mudcracked. They probably represent alternating layers of wave-ripple cross-stratified fine sands and suspension settle-out of mud, implying an on-off wave regime. Furthermore, these rocks are not bioturbated, they contain stromatolites which are otherwise rare in the Manlius Formation, and associated thrombolites contain no microfossils. These observations suggest that this is the deposit of a subenvironment with waters inimical to organisms. Our best guess is that this subfacies represents some kind of restricted pond or lagoon with elevated salinities developed behind a lateral barrier.
The grainstone subfacies surrounds thrombolites at the base of the Clockville section and is likewise interpreted as a shallow subtidal shelf deposit. The common planar stratification implies that deposition commonly occurred beneath an upper-stage plane bed generated by either unidirectional or oscillatory (wave) currents. The common fining-upwards sets capped by finer-grained dolomites suggests these are storm deposits.
The thin beddite subfacies has long been recognized as subtidal shelf deposits (Laporte 1967; Walker and Laporte 1970). We concur. However, we feel that there are two features of this rock type worthy of note.
First, these rocks have been severely effected by diagenesis. There is ample evidence of differential cementation and differential compaction in the common drag effects of layering around both hard skeletal elements and nodules of limestone. Moreover, the obvious association of the shaley dolomitic partings with compacted sediment opens the door to consideration of pressure-solution dolomitization (Wanless, 1979; and Logan and Seminiuk, 1976). Indeed, most of the preserved layering here might be due to early, layercake diagenesis argued for by Bathurst (1987). The nature and significance of dolomite and shaley dolomitic partings (which, after all apparently define the main layering style) in these rocks must await formal study of the diagenesis of this formation.
The second point about the thin beddite subfacies of the Manlius Formation is that we see absolutely no compelling reasons to subdivide these rocks. The nature of the diagenetic overprints, the nature of the internal sedimentary structures, and the nature of their preserved fossils suggest that these rocks are rather insensitive indicators of water depth. Moreover, there is no one no parameter in these rocks that is sensitive to water depth. Wave ripple marks preserved on bedding surfaces would be an obvious place to start considering their potential for quantitatively giving water depth (Komar, 1974; Clifton, 1976). However, much of the waviness of bedding surfaces in this subfacies may be the result of diagenesis. As an example of the difficulty in interpreting water depth we would like to draw attention to the grainstone coset 8 m above the base of the Clockville section. At first consideration, it may seem that this would be a good place to "draw a line" separating deposits of different water depth. However, examination of the thin beds above and below this layer will reveal similar, thinner sets of coarse grainstones. In this respect, and in its overall geometry and crude internal organization, this grainstone most likely represents a storm deposit on the shelf similar to those from siliciclastic shelves. We do not think that such "event layers" are necessarily good candidates for major changes in depositional environments.
CONCLUDING REMARKS
We hope that we have shown that the sedimentary and diagenetic features of the Manlius Formation are a storehouse of information that is vital to any attempt to unravel the depositional significance of these rocks. Questions need to be answered before the larger-scale significance of these rocks can be addressed. What was the nature of the original deposits that were diagenetically altered into the thin bedded subfacies? What is the sequence of diagenetic events that effected these deposits? Are there storm deposits preserved in this subfacies or are there significant depositional breaks? What is the nature of the small-scale, desiccating upward cycles preserved in the disrupted mudstone? How much time do they represent? Are they caliche soils like those capping Pleistocene carbonates of the Florida- Bahama Banks Province? Are there tepee structures preserved that imply early cementation?

STOP 1. Clockville Quarry

STOP 2. Jamesville Quarry

STOP 3. (Optional) Munnsville Quarry

A4: SEDIMENTOLOGY OF THE DENLEY LIMESTONE (MIDDLE ORDOVICIAN,TRENTON GROUP) IN CENTRAL NEW YORK
Charlotte J. Mehrtens
Department of Geology
Burlington, Vt. 05405
Introduction
The Denley Limestone of the Trenton Group (Middle Ordovician) in central New York is characterized by nearly 90 meters of alternating beds of limestone and shale. The origin of limestone and shale couplets in general is problematic, however, in the case of the Denley Limestone, the limestones can be shown to be bioclastic turbidites in origin. These bioclastic turbidites are recognized by Bouma divisions within the limestone beds. Interbedded shale horizons represent the in situ sediment. This sedimentologic interpretation has implications for the paleoenvironmental setting of the Denley Limestone.
This field trip will ask you to address the following questions: (1) How can resedimented carbonates be distinguished from in situ sediment? (2) How can tempestites be distinguished from turbidites? (3) Why should one bother with the tempestite/turbidite distinction?
FIELD TRIP ROAD LOG: SEE BRETT AND BAIRD, TillS VOLUME

A5: LATE WISCONSINAN GLACIAL LAKES OF THE WESTERN MOHAWK VALLEY REGION OF CENTRAL NEW YORK
Jack Ridge
Dept. of Geology
Tufts University
Medford, MA 02155
David A. Franzi
Center for Earth and Environmental Science
S.U.N.Y. Plattsburgh
Plattsburgh, NY 12901
INTRODUCTION
The glacial history of the western Mohawk Valley region (Fig. 1) is critical to evaluating the contemporaneity of glacial events in the Great Lakes region, the Hudson-Champlain Valley, and New England. Understanding the composition and stratigraphy of glaciolacustrine deposits is particularly important to defining the positions and advances of impounding ice lobes, the pattern of ice recession in the Ontario Basin, Mohawk Valley, and Adirondacks, and the timing of the eastward release of water from the eastern Great Lakes region during Late Wisconsinan time.
Until recently, considerable controversy existed over the character of ice recession and the existence of regional glacial lakes and their levels in the Mohawk Valley. Several early workers recognized the widespread evidence for eastward (Ontario Lobe) and westward (Mohawk Lobe) ice flow in the Mohawk Valley (Dana, 1863; Chamberlin, 1883, 1888; Brigham, 1898, 1908; Cushing, 1905; Miller, 1909). A lack of deposits that clearly define ice-marginal positions in the Mohawk Valley led Cushing (1905), Brigham (1911, 1929), and Fairchild (1912) to conclude that ice in the lowlands receded by stagnation and downwasting, rather than by backwasting of an active ice margin. Fairchild's (1912) reconstructions depict lowland ice lobes that surrounded an ice-free Adirondacks during deglaciation. Fairchild inferred that deep glacial lakes, which drained southward across the Appalachian Upland, were impounded between the Mohawk and Ontario Lobes (Fig. 1) during deglaciation. Brigham (1911, 1929) opposed this idea based on a scarcity of lacustrine deposits above an elevation of 200 m. Recent stratigraphic studies (Fullerton, 1971; Krall 1977; Franzi, 1984; Ridge, 1985; Muller and others, 1986; Ridge and others, 1990; 1991) have provided evidence that deep, regional preglacial lakes formed at the margins of active lowland ice lobes at elevations up to 475 m. The lowland lobes formed prior to the deglaciation of most of the central Adirondack highlands. Regional deglaciation occurred primarily by calving at deep water, active ice margins, but was interrupted by several episodes of lowland ice readvance.
The purpose of this excursion will be to examine the evidence and history of glacial lakes in the western Mohawk Valley region. The lithostratigraphic model for the West Canada Creek valley, the application of paleomagnetism, and the genetic interpretation of sediments as related to glacial dynamics will be discussed.

A5: LATE WISCONSINAN GLACIAL LAKES OF THE WESTERN MOHAWK VALLEY REGION OF CENTRAL NEW YORK

Swampy lowland to the west
Swampy lowland to the west is the channel leading south from Cedarville col.

STOP 1. Overview of Cedarville col (1210 ft)
Overview of Cedarville col (1210 ft) which is on the divide between the unadilla River (Susquehanna Basin) and Steele Creek (Mohawk Basin) drainages. Cedarville col served as the outlet for Lake Cedarville, a high level Valley Heads lake in the Mohawk Valley (Figs. 5 and 10-12).

Steele Ck. descends into Ilion Gorge
Steele Ck. descends into Ilion Gorge which exposes much of the late Ordovician through Silurian stratigraphy of the western Mohawk Valley. Red shale exposed in the gorge is the Vernon Shale which is the source of the red color in glacial units of the region. A large inwash delta at the mouth of Steele Ck. in the Mohawk Valley indicates that Ilion Gorge was largely cut during the late Pleistocene existence of Lake Amsterdam.

Town of Kast Bridge.
In the next mile, bluff section 828 (Fig. 17) will be visible across W. Canada Ck. The flat top of the bluff to the east is the surface of the Holland Patent Diamicton and silt and clay of the post-Holland Patent beds (Figs. 2 and 13).

Bluff section 811
Across W. Canada Ck. from campground is bluff section 811 (Fig. 17).

STOP 2. Fishing Rock Rd. bluff, section 324 (Fig. 17).
This section has Precambrian gneiss at road level with two striation directions overlain by thin, discontinuous till in the West Canada Diamicton. The diamicton is overlain by sand and gravel and mass flow diamicton beds of an esker/subaqueous fan complex in the base of the upper Newport Beds. Fan deposition at this location may have been triggered by the lowering of Lake Newport at the close of pre-Valley Heads glaciation (Figs. 2 and 9).

West Canada High School.
The school sits on fluvial terraces graded to Lake Amsterdam or its immediate predecessor in the Mohawk Valley.

Rt.28 crosses over White Creek.

Bluff section 451 (Fig. 17)
Bluff section 451 (Fig. 17) is the embankment to the right.

STOP 3: Newport bluff, section 447 (Fig. 17).
This bluff exposes the top of the pre-Valley Heads section (Middleville Fm.) which is overlain by the Valley Heads section (Poland Fm.). The two units are separated by the Shed Brook Discontinuity at this exposure (Fig. 2).

Workshop site of Linus Yale
The octagonal limestone house at this corner is the workshop site of Linus Yale, inventor of the Yale Lock.

Gage Rd. climbs to the top of a hill
Gage Rd. climbs to the top of a hill composed of the entire glacial section of the W. Canada Valley (Fig. 2).

Cross over White Ck., enter the Factory Brook valley.

STOP 4: Factory Brook bluffs, sections 225-226 (Fig. 17).
The bluff sections across Factory Bk. contain almost the entire pre-Valley Heads section (Fig. 2). The top of till in the West Canada Diamicton at this exposure shows subglacial grooving that records Mohawk Lobe ice flow to the northwest. The top of pre-Valley Heads deposits (upper Newport Beds) are subglacially deformed beneath Valley Heads till in the Norway Diamicton, an Ontario Lobe deposit from the Hinckley-St. Johnsville Readvance (Figs. 10 and 12).

STOP 5: Poland clay pit, section 338 (Fig. 17).
This section exposes lacustrine sediments in the lower part of the Valley Heads Poland Fm. Two important transitions occur in this section. A sudden change from lacustrine sand to dark gray silt and clay varves in the pre- and post-Hawthorne beds marks rising water levels during the initial impoundment of Lake Cedarville. A transition higher in the section from dark gray varves, with only gray ice-rafted pellets (post-Hawthorne beds), to pinkish gray varves, with red and gray ice-rafted pellets (pre-Norway beds), represents the transition from Mohawk to Ontario provenance that occurred between the Salisbury and Hinckley-St. Johnsville readvances. The pre-Norway beds are subglacially deformed beneath till in the Norway Diamicton.

Breakout channel of Lake Miller
Rt.8 North enters the breakout channel of Lake Miller as it passes by Hurricane Rd.

STOP 6. Lake Miller delta
Lake Miller delta at the maximum position of the Hinckley-St. Johnsville Readvance (Valley Heads, Ontario Lobe, Figs. 10 and 12). Burt Rd. crosses the distal part of the delta which is graded to a water level of 1410 ft that drained across a spillway into Spruce Creek. Map analysis of delta and spillway elevations in the upper West Canada Valley from this stage of Lake Miller indicates that isostatic tilting in the region was about 4-5 ft/mile. When the Ontario Lobe began to recede, Lake Miller drained southward across the delta by way of the breakout channel along Rt. 8 which served as the spillway for a second stage of Lake Miller at about 1390 ft.

Cross Black Creek

Ohio Sand Plain
The next several miles of the trip will cross areas of the Ohio sand plain which represents deposition of deltaic and lake-bottom sand in Lake Miller. Sand in this area sits on clay and silt of the Newport Beds (pre-Valley Heads).

STOP 7: South shore bluffs of the Hinckley Reservoir.
THIS AREA IS PRIVATE PROPERTY!
The bluffs expose the lower through upper Newport Beds, deposited in Lake Newport during the time of the West Canada Readvance which was confined to the lower W. Canada Valley (Figs. 7-9). Readvance activity of the Mohawk Lobe is marked by provenance changes in varves at the Hinckley bluffs. Varves at the base of the section are sandy, have an Adirondack source, and overlie a very sandy and bouldery Adirondack diamicton. The sandy varves give way to clayey dark gray varves of Mohawk Lobe provenance. Mohawk Lobe varves are then overlain by Adirondack varves marking the recession of the Mohawk Lobe and dropping water levels in Lake Newport. The Hinckley bluffs also have spectacular slump and load structures.

Town of Hinckley.
The bluff tops across W. Canada Ck. to the south are ice-contact deltas built along the receding margin of the Ontario Lobe (Hinckley-St. Johnsville Readvance, Figs. 10 and 12). The deltas are graded to the second stage of Lake Miller which drained through the channel seen along Rt.8 near Stop 6.

North of the town of Prospect.
Prospect sits on the surface of a delta built into Lake Prospect (Franzi, 1984) which formed for a short time during the drainage of Lake Cedarville in the Mohawk and W. Canada valleys.

STOP 8. Bluffs on Cincinnati Ck
Bluffs on Cincinnati Ck. expose later Valley Heads deposits in the upper W. Canada Valley. The base of the section is esker/subaqueous sand and gravel overlain by varves with red ice-rafted pellets (post-Norway beds). Till in the Holland Patent Diamicton overlies the post-Norway beds and it is overlain by an ice-contact delta of Lake Gravesville (Figs. 10 and 13). This locality is just inside the eastern limit of the Barneveld-Little Falls Readv. of the Ontario Lobe .

STOP 9: River Rd. sand pit.
This section is representative of exposures in the broad undulating plain between Rome to the west and Ninemile Ck. to the east. It provides evidence for the final readvance (post-Valley Heads) of the Ontario Lobe into the Mohawk Valley (Ninemile Readvance, Figs. 10 and 16). The section has 0.5-2.0 m of red till (Rome till of Muller and others, 1986) overlying about 10-15 m of lacustrine sand that was deposited in Lake Amsterdam. The sand is subtly deformed at the base of the till which does not occur east of Ninemile Ck.

Pass by landfill entrance on right.
Hill top to right is the Whitesboro Terrace.

STOP 10. The pit shows the interior of the Whitesboro Terrace
The pit shows the interior of the Whitesboro Terrace which is an esker-fed, ice-contact feature formed at a recessional position of the Ontario Lobe during the last gasp of Valley Heads glaciation (Figs. 10 and 15). The terrace appears to be an ice-contact delta because it has 5-10 m of fluvial gravel capping lacustrine sand along what resembles a deltaic topset/foreset contact. However, the contact does not represent a horizontal surface and is tilted regionally down to the east-northeast. The gravel was deposited on a fluvially scoured surface that probably represents trimming of the sand (delta or subaqueous fan?) in response to falling lake levels in the Mohawk Valley. The gravel cap represents the first Ontario Lobe, ice-contact deposit graded to a water level less than 500ft in the western Mohawk Valley (Lake Amsterdam). Further east in the western Mohawk Valley Lake Amsterdam is only recorded by inwash deltas.

A6: GEOLOGY OF THE MOHAWK AND BLACK RIVER VALLEYS - A FIELD TRIP FOR EARTH SCIENCE TEACHERS
Barbara J. Tewksbury
Hamilton College
Clinton, NY 13323
Robert H. Allers
Vernon-Verona-Sherrill High School
Verona, NY 13478
Introduction
Rocks exposed in the Mohawk and Black River Valleys consist of a sequence of Late Precambrian metamorphic rocks unconformably overlain by a sedimentary succession ranging from Cambrian through Silurian in age. A veneer of unconsolidated Pleistocene sediments mantles the bedrock. Changes in plate tectonic setting with time are reflected both directly and indirectly in the changing character of the rock record, and Pleistocene deposits in the region provide clues to Late Wisconsinan deglaciation. The purpose of this field trip is 3-fold: 1) to examine the character of the bedrock, 2) to see how changes in plate tectonic setting are mirrored by changes in the rock record, and 3) to study the record of Late Pleistocene glacial and peri-glacial environments of central New York. The introductory text provides background on the bedrock geology, plate tectonic setting, and Pleistocene history of the region.

A6: GEOLOGY OF THE MOHAWK AND BLACK RIVER VALLEYS - A FIELD TRIP FOR EARTH SCIENCE TEACHERS

Kame delta on tree-covered hill to the east

Kame terraces on west side of road
(see description under STOP 1 )

Hamlet of Deansboro

Crevasse fillings on west side of road
(see description under STOP 2).

Eastern Rock Products Quarry
Good outcrops of Devonian Helderberg Group.

STOP 1. VALLEY HEADS MORAINE, ORISKANY FALLS
Looking south from this vantage point, one can see topography very different from that to the north in Oriskany Creek valley. At Oriskany Falls, a flat-floored valley gives way to irregular hills and hummocky topography. These hills and depressions are known as kame and kettle topography and are part of the Valley Heads Moraine. These deposits at Oriskany Falls are part of a large belt of recessional moraines marking a still-stand or readvance of the Wisconsinan glacier in New York State. The Valley Heads Moraine marks the southernmost extent of the ice sheet to be visited on this field trip. The Olean and Binghamton stages are also marked by similar deposits farther to the south, but the Valley Heads Moraine is the most distinctive belt of morainal deposits in central New York.
The hummocky terrain at Oriskany Falls formed by differential melting of sediment-laden ice at the glacier terminus. Ice advance from the north and ablation (primarily due to melting) must have reached equilibrium, and, for a time, the ice front neither advanced nor retreated. Judging from the size of the Valley Heads Moraine, this still-stand may have lasted for as much as 100 years.
The moraine loops across the valley, marking the lobate shape of the glacier. Some of the morainal deposits were created as dirty ice melted and released entrained sediment. This process is similar to the process that forms the piles of sediment one finds along roadsides or driveways when snowbanks melt in the spring. Unsorted, unlayered sediment marks the areas where snowbanks were piled in the winter. By analogy, piles of ablation till mark the terminus of the ice sheet and are composed of generally unsorted and unstratified sediment. Stagnant ice blocks trapped in the sediment later melt out, leaving depressions known as kettles (figure 5).
Many moraines contain considerable quantities of stratified drift in addition to unstratified ablation till. These stratified sediments are deposited in depressions on the moraine surface by running water- primarily meltwater from the wasting ice sheet. Within individual layers, sediments are typically moderately well-sorted, although grain size ranges widely from layer to layer. Many of the sediments are fluvio-glacial, and cut and fill structures and cross-bedding are common. While buried ice blocks remain intact, stratified drift occupies depressions in the morainal surface. Once buried ice blocks melt and produce kettles, the topography inverts, producing hills of stratified drift known as kames. The inversion process commonly disrupts stratification in the kame deposits. This hummocky topography is known as a kame and kettle moraine. Most kame and kettle moraines are also dissected by meltwaters that spread the eroded material down-valley in outwash plains. Were we to drive south of Oriskany Falls to route 20, we would be able to see the broad flat outwash valleys developed south of the Valley Heads Moraine. Scattered kettles occur on the outwash plain, and one of the best sits in the front yard of the Madison School on route 20.
In the valley to the north of Oriskany Falls, one can see crevasse fillings (at road log mile point 6.2). These kames of stratified drift were formed as sediment accumulated in large cracks or crevasses in the ice. When the ice melted, these sediments were left as en echelon ridges parallel to one another but at an angle to the valley walls. In addition, one can also see examples of kame terraces along the valley walls to the north (road log mile point 5.7). These formed along the sides of the stagnant ice, as sediment-rich meltwater and rainwater poured off the ice and hills separating the ice tongues. As with all kame deposits, these are composed of stratified drift. However, many of the kames show disrupted stratification, produced as ice melted and removed support from the sediment, causing slumping and faulting.

Large glacial erratic on the west side of the road.

Good view to the W over Sconondoa Valley and Oneida Lake.
Meltwater channel and delta complex can be seen south of Vernon Center in Sconondoa Valley.

STOP 2. RIVERSIDE MALL
Here, we will see a very different type of Pleistocene deposit than the one we saw at Oriskany Falls. Sediments of the Valley Heads Moraine are ice contact deposits; the sediments at Riverside Mall are pro-glacial lake sediments, deposited in glacial Lake Iroquois or Amsterdam. The slope north of the parking lot is underlain by dark-colored, very fine-grained, finely laminated sediments. At the top of the slope, sediments are conspicuously coarser, composed of fine to medium sands with some pebbly layers.
The fine-grained sediments are varved clays, or rhythmites, composed of layers of gray clay alternating with organic-rich silty layers. Overall fine grain size indicates a low-energy environment, away from lake inlets and deltaic complexes. The layers represent seasonal accumulations, and each couplet (varve) represents one year of sediment accumulation. The silty layers form during rapid sediment influx and probably represent summer accumulation, when the ice is melting and releasing sediment to the lake. The clays accumulate during the winter, when the ice is delivering little sediment to the system and proglacial lakes are iced over. Winter accumulations consist only of very finely-divided material that settles very slowly out of the water column. Such material accumulates year-round but is swamped during the summer by coarser detritus fed into the system. Summer layers here are thinner than the winter layers, probably because of the short duration of the melting season.
Clays are notoriously unstable when wet -- witness the periodic devastation caused by clay-lubricated mudslides in California. With the right amount of water, clays and silts are very susceptible to liquefaction when shaken. Vibration causes particles to lose frictional contact with one another, and the mass becomes temporarily liquified and has no shear strength. Once vibration stops, the mass regains its shear strength. A close look at the mall parking lot will reveal many humps and swales, and even more numerous patches. The parking lot is underlain by varved clays and silts. When moisture content is right. vibration from vehicles induces some liquefaction, and the parking lot surface deforms in response to flow of material beneath it. A good drainage plan would have prevented much of the problem.
As you walk northward up the slope from the parking lot, you will notice a distinct change in sediment from varved clays to fine-grained sands. These sands were deposited in an environment of higher energy than that in which the varved clays were deposited.
Sediments at this stop exhibit a nice vertical facies change, indicating a change in lake depth with time. In a typical lake, the coarsest sediment settles in shallow, high energy water nearest the shore and lake inlets. As coarse sediment settles out, only finer material passes into deeper water, and only clays and organic material accumulate in the deeper portions of the lake. The change upslope at Riverside Mall from varved clays to sands indicates shallowing of water with time, either by progradation of a delta or by general lowering of lake level during ice retreat.
In some of the glacial lakes (especially Lake Iroquois), carbonate-producing animals and plants flourished, and layers of marl occur between the coarse sand zones and the silt zones. Marl is a calcareous sediment; in this area, marls are typically rich in shells of tiny gastropods and pelecypods and remains of a calcareous plant known as chara.

Well-developed Pleistocene ground moraine on west side of road.

Nice field of Pleistocene erratics to west of road.

Well-sorted Pleistocene fluvio-glacial sands to west of road.

The large, elongate hill east of the road is Park Hill
The large, elongate hill east of the road is Park Hill and consists of dissected Pleistocene outwash. Several sand and gravel operations exploit the deposit.

Traversing bottom of glacial Lake Port Leyden.

Glacially-polished bedrock knobs east and west of the road.

Delta tops in distance
The horizon to the east across the Black River Valley has a very uniform elevation. That straight horizon corresponds to a well-developed, flat topographic surface at an elevation of about 1200-1250' that shows up very well on the topographic maps of the Brantingham and Port Leyden quads. These flat surfaces are delta tops, formed as sediment was deposited into glacial Lake Port Leyden during Lhe last part of the Pleistocene. Glacial Lake Port Leyden must have been at least as deep as the tops of the deltas; it was no small lake. A look at the topographic maps will show many closed depressions on the delta tops; these were presumably formed as grounded ice, partially covered with deltaic sediments, melted and caused subsidence. The delta slopes have been somewhat dissected since. Glacially-sculpted Deerlick Road lies in the Black River Valley east of the road; it appears to be a roche moutonee.

Good exposure of glacially-polished bedrock east of the road.

Route 12 crosses Roaring Brook.

Floodplain of the Black River
Which floods with great regularity.

Pleistocene boulder fields on west side of road.

STOP 3: CROGHAN ROADCUT (and that's no baloney!)
The rocks in this spectacular roadcut are part of the suite of metasedimentary and metaigneous rocks that make up the bulk of the Adirondacks. These rocks were deformed and metamorphosed during the Grenville Orogeny (1020-1100 Ma), at depths of about 25km below the surface, temperatures of 700-720°C, and pressures of about 7 kilobars. They are quite thoroughly cooked. They are also deformed, and all lithologies in this outcrop, including the ones of igneous parentage, show compositional layering and/or planar alignments of minerals (foliations) acquired during deformation.
There are 3 major lithologies present in this roadcut 1) a mildly-foliated, coarse-grained pink granitic gneiss consisting of pink K-feldspar, plagioclase, quartz, and variable amounts of hornblende with accessory magnetite, biotite, apatite, and zircon, 2) a foliated, very coarse-grained pink augen ("eye") gneiss, with enormous pink feldspar grains up to 2-6 cm long set in a matrix of plagioclase, hornblende, and quartz, and 3) well-foliated, banded gneisses composed of black, pyroxene-biotite and hornblende-biotite gneisses interlayered with pink to gray granitic and augen gneisses. The dark-colored gneisses are composed of biotite, plagioclase, and hornblende or pyroxene, with accessory apatite, zircon, and magnetite. The light-colored interlayers are similar in composition to the granitic gneisses in the outcrop.
In addition to these 3 major lithologies, this outcrop contains minor amounts of amphibolite, biotite-oligoclase augen gneiss, quartzofeldspathic hornblende gneiss, and biotite-plagioclase schist all interlayered with granitic gneisses and granitic augen gneisses.
The foliation is defined differently in each of the 3 main lithologies. In the granitic gneiss, the foliation is defined both by the parallel alignment of dispersed biotite and by alternating layers of different grain size (but similar composition). In the augen gneiss, the foliation is defined by large, flattened and streamlined K-feldspar grains outlined by ribbons of quartz. The foliation defined by the flattened grains is enhanced by an irregular compositional layering defined by lenses of pink K-feldspar (commonly strung out into layers) alternating with stringers of quartz, plagioclase, and hornblende. In the banded gneiss, foliation is defined primarily by alternating layers of different compositions, one light-colored and rich in quartz and feldspar, the other dark-colored and rich in mafic minerals. Within the dark-colored gneiss, foliation is enhanced by the parallel alignment of biotite. None of the 3 major lithologies has enough mica in it for the foliation to also be a good rock cleavage direction. As a result, all of the major lithologies are blocky and tough.
Although these rocks are metamorphic, the outcrop displays many classic relict igneous features. The granitic gneisses were evidently originally granitic magmas that thoroughly and intimately invaded a country rock of dark-colored gneisses. The dark-colored gneisses, then, might well be xenoliths, remnants of the country rock caught up during intrusion of granitic magmas. The great variety of grain size amongst the granitic gneisses, and the complicated multiple cross-cutting relationships attest to a period of multiple intrusions. Evidence in this outcrop also suggests that deformation was going on as the magmas were being intruded (i.e., that the granitic magmas were syntectonic). Some folds in the dark-colored gneisses are truncated by the granitic gneisses, implying intrusion after folding. On the other hand, some granitic gneisses interlayered with the dark-colored gneisses are folded right along with the dark-colored gneiss. In fact, some of the extremely flattened augen in the augen gneisses are folded. Both suggest folding after granite emplacement. Folding after and folding before granite emplacement implies protracted and syntectonic intrusion. Because all units are foliated, deformation must have outlasted the intrusive episodes.
The other relict igneous features in this outcrop are the augen in the augen gneisses. The augen gneiss may also be referred to as a megacrystic gneiss, in allusion to the enormous size of the deformed feldspar crystals that make up the augen. The metacrysts or augen are very likely relict phenocrysts formed during early slow cooling of a granitic magma with a two-stage cooling history.
As suggested in the previous paragraph, the protolith (pre-metamorphic rock type) for the granitic gneiss was probably a granite. Metamorphism did very little to its original mineral composition, because temperatures during metamorphism were nearly as high as the temperature of a granitic melt at those depths. In other words, the minerals in the granite were perfectly happy under the conditions of metamorphism. Even though the overall mineral content did not change appreciably during metamorphism, individual mineral grains did become unstable and recrystallize in new orientations in response to deformation in the rock. In this manner, the granite acquired a foliation of recrystallized and aligned biotite and became a granitic gneiss. The foliation defined by interlayers of different grain sizes is likely due in part to inheritance of primary textural differences and in part to deformation.
The protolith for the augen gneiss was probably a porphyritic granite. Its metamorphic minerals are not substantially different from those in the protolith, but deformation and recrystallization produced a well-developed foliation in the rock. If you look carefully at the augen gneisses in this outcrop, you will see that there is a range in texture from blocky pink feldspars set in a poorly-foliated matrix to stringers of pink feldspar set in a well-foliated matrix. These differences in texture undoubtedly result from differences in intensity of deformation. As the amount of shearing in a layer increases the feldspar tabs flatten. Strain is highest along the margins of the grains, particularly at the corners; the edges and corners of the feldspars begin to recrystallize into networks of tiny, stable feldspar grains (figure 6). These tiny grains are then no longer part of the larger feldspar tab - they have been, in effect, transferred to the matrix. Plastic flattening of the grain, then, is accompanied by some grain size reduction and a change of grain shape from blocky to eye-shaped. Some of the large feldspar grains are also fractured, if plastic deformation in the grain can't keep up with deformation in the rock. Changes are also happening in the matrix minerals. Platy and prismatic minerals such as biotite and hornblende recrystallize parallel to the flattening plane of the feldspar tabs, creating a foliation wrapping around the developing augen. Coarse quartz grains become flattened, ribbon-shaped grains oriented parallel to the foliation and wrapping around the augen. Many of these deformed quartz grains undergo the same kind of dynamic recrystallization that affects the margins of the feldspars. New, tiny grains of quartz form from the old strained grains. Quartz is very susceptible to the dynamic recrystallization process and undergoes grain size reduction much more readily than feldspars. Therefore, when you look at the augen gneiss, realize that some of the disparity in grain size between augen and matrix was produced during deformation. In fact. many augen gneisses of the world began life as uniformly coarse-grained rocks: not all augen gneisses had porphyritic parents.
Determining the protolith for the dark-colored gneisses is somewhat more problematic, and both igneous and sedimentary protoliths are possible. The dark-colored gneisses are intimately interlayered with light-colored gneisses and augen gneisses to form packages of conspicuously banded gneiss. Questions concerning the origin of the banding cannot be answered unequivocally. The fact that many of the light-colored layers can be traced to larger masses of granitic gneisses suggests that at least some of the banding may be intrusive, the result of intimate interfingering of dark gneiss and granitic magma (a lit-par-lit gneiss). Layers that cannot be traced to a granitic mass may be either light-colored layers in the original country rock, or granitic material derived very locally by partial melting of the dark-colored gneiss and creation of migmatites. Considering that metamorphic temperatures were very close to the minimum melting temperatures of many types of metasediments, the ultimate source of the large volumes of granitic magma in the Croghan area was very likely the metamorphic complex itself. Local partial melting of the dark gneisses may have taken place as well.
After viewing the Precambrian geology, let's jump ahead about a billion years to see what effect the Wisconsinan ice sheet had on this locality. The top of the outcrop is a smoothed and polished surface, produced as glacial ice with entrained sediment sand-papered and rounded the hard Precambrian rock. Some differential erosion can be seen along zones of dark gneiss. The grooves and shallow potholes suggest that the outcrop may not only have been glacially scoured but also eroded by running water. Marginal or subglacial meltwaters, particularly related to a stagnant ice mass, are good candidates.
Proceed eastward over the top of the outcrop to a low exposure of Precambrian bedrock about 30 m away. This outcrop displays distinctive scratches and grooves (glacial striae) trending S10-20°W, parallel to the last ice movement direction in the area. Looking south from this outcrop, you will see a hill with a sand quarry. This hill is part of a series of hills extending the entire length of the Lowville quadrangle. The line of hills trends north-south, with a slight dog-leg near this stop. The deposits that underlie these elongate hills are largely unconsolidated sediments dating from the late Pleistocene. As discussed at stops 1 and 2, Pleistocene deposits in this area include ground moraine (both ablation and lodgement till), morainal ridges (typically composed of till overlain by patchy stratified drift), kame terraces and crevasse fillings (stratified drift), eskers (stratified drift), outwash (fluvial deposits), and pro-glacial lake deposits (beach and deltaic deposits, varved clays, etc.). Each of these deposits has distinctive characteristics, and examination of the deposits in this quarry should allow us at least to rule out some of the possibilities. This deposit was originally described by Buddington (1934) as a moraine. However, close examination shows structures consistent with sediment deposited by running water, rather than directly by melting ice. If these deposits are ice contact sediments, deposition was dominated by fluvioglacial processes.
Sediments in the quarry are conspicuously stratified. Scour and fill structures are common. Cross bedding occurs at many different scales, but many layers exhibit planar laminae. A majority of the deposit consists of sand-sized grains, although there are some layers of very fine grains as well as some layers of pebbly sand. Individual layers are typically moderately well-sorted to well-sorted. The characteristics of sorting and stratification in these sediments indicate deposition from a moving current; direct ice deposition does not produce stratified and sorted sediments. Therefore, these sediments are not tills.
Cut and fill structures, cross-bedding, and some pebble imbrication are consistent with fluvial deposition. At this stop, stratified sediment lies directly on water-scoured Precambrian bedrock; there is no intervening morainal till. It appears, then, that at least this portion of the deposit does not represent a veneer of stratified drift over ridges of morainal debris.
Some of the horizons in the quarry consist of thinly laminated fine sand and silt. Cross-bedding is absent, and individual layers are laterally extensive and easily-traceable. These may represent sediments deposited in closed depressions such as small ponds. Some of these fine-grained layers contain cobbles that may well be dropstones.
The fact that these deposits are part of an elongate but not sinuous ridge system suggests that these deposits are not part of an esker, a pro-glacial lake, or an outwash plain (although dissected outwash is a possibility). A stratified ice contact deposit is the most logical choice - perhaps an ice-marginal deposit or a very large crevasse filling in stagnant ice. The fact that slopes on the west sides of the hills are steeper than those on the east sides suggests that the main ice contact side of the deposit may have been on the west.

Tug Hill Plateau
Spectacular view to the west of the Tug Hill Plateau, underlain by Middle and Upper Ordovician sedimentary rocks.

An even better view of the Tug Hill Plateau.

STOP 4. DADVILLE QUARRY
After repeated searches, neither of us has ever found an exposure of the Precambrian/Paleozoic unconformity (Plate I) in the Black River Valley, although such exposures have been reported in the literature (Miller, 1910). The unconformity is spectacularly exposed in roadcuts near Kingston, Ontario, but that's a bit far away for this field trip. The outcrops at the Dadville Quarry constrain the position of the unconformity better than almost anywhere in the Black River Valley, and we'll have to settle for that.
Precambrian granitic gneisses crop out on the north side of the road in front of the Highway Department Building. Standing on the Precambrian, one can look east and see many knobs of Precambrian rock scattered throughout the Black River Valley and nearly buried by Pleistocene sediments. Directly southeast across the road, Middle Ordovician limestones of the Black River Group are exposed in an active quarry. The trace of the unconformity must lie just below the quarry floor, swinging around the base of the hill and across the road west of where we are standing. From the base of the hill, the unconformity dips very gently (only a few degrees) to the southwest.
Why can't we see the unconformity in the quarry? Surely they must have quarried through to the Precambrian in places, you think. In point of fact, they haven't quarried to the Precambrian, and a look at the stratigraphic column in Plate I will tell us why. The quarry owners are interested in limestones, and the Black River Group has good limestones in all but the Pamelia Formation at the bottom of the Group. As soon as they reached the Pamelia, they stopped quarrying.
A look at the topographic map would show that the position of the unconformity is marked here by a distinct break in topography. As we continue to drive south, you might find it interesting to check the topographic map for other breaks in slope, and examine the countryside and outcrops to see whether those breaks in slope mark the Precambrian/Paleozoic unconformity or not.

Bench in the Paleozoic
The houses on the left are perched on a bench in the Paleozoic that marks the contact between the Black River Group and the Trenton Group, both of Ordovician age. That bench and contact can be traced south on the topo map from stop 4. The next major bench to the west lies at a stratigraphic horizon within the lower portion of the Denley Limestone.

Crossing Roaring Brook.
Precambrian basement rock is exposed in the field to the east of the bridge, and Paleozoic sediments crop out immediately west of the bridge in the stream channel. The unconformity must lie somewhere between the 2 exposures, although the actual contact is not exposed at the surface.

Precambrian gneisses and Paleozoic benches
Rounded knobs of Precambrian gneisses dot the field to the east of the road; Paleozoic sediments begin to the west of the road at the first topographic rise. Town of Glenfield to the east The topo map shows how well the topography reflects the geology. The base of the first sharp slope west of Glenfield lies at the Precambrian/Paleozoic unconformity. The first bench marks the top of the Black River Group. The second major bench marks a horizon within the lower Denley Limestone. The third bench marks the top of the Denley, and the 4th bench marks the top of the Steuben Limestone. The base of the major slope at the Whetstone Gulf Campground marks the contact between the Steuben Limestone and the Utica Shale. The last bench lies at the contact between the Utica Shale and the Lorraine Group (equivalent to the Frankfort Shale).

Pleistocene glacial deposits mask most of the rocks near the unconformity.

Route 12 lies on Precambrian bedrock
An outcrop of the Pamelia Formation (lower Black River Group) lies approximately 50 m west up Snugsboro Road.

Outcrops of the lower Black River Group
Outcrops of the lower Black River Group line the lower part of Turin Road to the west.

Road has crossed the unconformity
Between the last mileage point and this one, the road has crossed the unconformity; outcrops of the Lowville Formation (Black River Group) lie immediately west of the road.

Tracks approximately follow the unconformity.
From here south, the railroad tracks approximately follow the unconformity.

Outcrop of Precambrian granitic gneiss east of road
Glacial deposits blanket much of the Precambrian in this area.

Precambrian diopside-quartz-phlogopite gneiss
Precambrian diopside-quartz-phlogopite gneiss on the east side of the road. The protolith for these metasedimentary units was probably a dirty carbonate, such as a sandy dolostone.

Historic marker for the Black River Canal.
The Canal was completed in 1855 and linked Carthage and Rome. In a 35- mile stretch through the steepest terrain, workers constructed 109 locks. The locks were built with limestones quarried from the Black River Group, as were many of the dove-gray stone buildings in the North Country.

STOP 5. SUGAR RIVER, EAST OF ROUTE 12
THIS IS PRIVATE PROPERTY. You MUST obtain permission from Barrett Paving Company (the quarry owners) if you wish to examine the rocks along the Sugar River. The owners have been very generous in the past in allowing groups to visit the exquisite features on their property. However, repeated unauthorized entry by inconsiderate geologists to properties at many other places around the country has rightfully angered many property owners. As a result, many classic localities are now completely off limits, even to those who properly seek permission. Don't take a chance on spoiling the Sugar River spot for everyone else. Be sure to get permission. Encourage others to do the same.
ALSO - BEWARE THE UNUSUALLY LUSH AND PREDATORY POISON IVY.
These beautiful gray limestones are part of the Watertown Formation at the top of the Black River Group (Plate I) and were deposited as a subtidal sequence on the North American passive continental margin during the Early Middle Ordovician. At several stops on this field trip, we will be examining carbonate sequences. Limestones and dolostones, composed of calcite and dolomite respectively, exhibit a wide range of textures and structures, but all share the common characteristic of being biogenically-derived. Very few post-Precambrian carbonates are pure, non-biogenic chemical precipitates. In addition, one should keep the distinction in mind between detrital clastic rocks such as sandstones and shales, whose fragments are derived from weathering of a distant source, and carbonates, whose fragments are derived very locally by organic precipitation of calcite. Neither animals nor plants precipitate dolomite, and virtually all dolomite in the sedimentary record results from replacement of calcite by its magnesium-rich counterpart, dolomite.
In order to help unravel the environment of deposition of a carbonate rock, it is useful to know in what form the calcite or dolomite occurs in a rock. Calcite can occur in a carbonate rock as skeletal debris, carbonate mud, sparry calcite, intraclasts, and pellets; dolomite can occur as early dolomite or secondary dolomite.
Skeletal debris consists of the remains of organisms, sometimes well-preserved in life position and not transported very far. Skeletal debris commonly consists of broken and disarticulated fossils and may be as fine as silt-sized particles.
When communication by currents or biologic activity reduces fossil fragments to mud-sized particles, the material is called carbonate mud. Lithified carbonate mud is referred to as "micrite"- microcrystalline calcite.
Sparry calcite is coarsely crystalline calcite precipitated-as a secondary mineral in pores and burrows. Some skeletal carbonates have a micritic matrix, others have a sparry matrix, depending upon whether the environment winnowed out very fine carbonate particles at the time of deposition.
Intraclasts are non-skeletal fragments >.2mm in size and associated with erosional intervals. They represent fragments of previously-deposited and partly-consolidated sediment (very locally-derived, of course).
Many pellets are probably intraclasts <.2mm in size, although some may well be fecal pellets.
Early dolomite commonly occurs in thin laminae and forms by migration of magnesium-rich waters upward through the sediments, followed by penecontemporaneous replacement of calcite by dolomite. Early dolomite is almost always found in supratidal settings.
Secondary dolomite forms well after deposition of the sediment and is highly variable, filling vugs, replacing calcite, or cementing clastic rocks.
A given carbonate rock may be composed of any combination of the ingredients listed above. Which components are combined and how they are combined governs the appearance of any individual carbonate rock. The word "limestone" describes anything from a hash of boulder-sized fossil fragments to a featureless, ultrafine-grained micrite. In self-defense, sedimentologists have derived a whole raft of esoteric terms ·to convey more than simple "limestone". The following definitions should help you to wade through most field guides:
calcirudites: carbonate equivalent of conglomeratic grain size
calcarenites: carbonate equivalent of sandstone grain size
calcisiltites: carbonate equivalent of siltstone grain size
calcilutites: carbonate equivalent of mudstone grain size
micrite: limestone formed from a carbonate mud
biomicrite: limestone formed from skeletal debris & carbonate mud
biosparite: limestone formed from skeletal debris & sparry calcite
Grain size is generally indicative of the energy of the environment, although one must bear in mind that large fossils do not by themselves indicate a high energy environment, because the animals lived in the environment and were not transported there.
If exposed to periodic exposure and dessication, carbonates may show mudcracks and local erosion surfaces. If deposited by currents, carbonate sediments may be cross-stratified. If burrowing organisms lived and fed in the carbonate substrate, the sediment may show burrows (horizontal or vertical). Active bioturbation (i.e., churning of the sediment by burrowing organisms) may completely destroy any fine-scale depositional structures such as bedding or lamination.
The Watertown Formation is a very dark gray limestone with fossils and fossil fragments floating in a very finegrained matrix. The matrix is micritic, and "dumpiness" of the micrite has prompted Walker (1973) to suggest that the micrite may have been pelletal. Bioclasts {both unabraded fossils and abraded fossil fragments) generally make up 10-30% of the rock, although percentages range as low as 4% and as high as 53% (Walker, 1973). The more fossiliferous lithologies would be properly called biomicrites. In all cases, bioclasts "float" in a matrix of micrite. Black chert nodules are common throughout the unit.
Stratification is virtually absent in the Watertown Formation, because the carbonate muds were completely churned by burrowing organisms who ate their way through the soft sediment. Much of the pelletal texture in the micrite may have originated as fecal pellets excreted as these organisms reworked the sediment. Networks of horizontal burrows thoroughly mottle this limestone and show up well on weathered horizontal surfaces. Mudcracks are absent, as are intraclasts and erosional intervals. Sparry calcite is confmed to burrows.
Fossils in the Watertown Formation are illustrated in figure 7 and include:
rugose (horn) corals (Lambeophyllum)
tabulate corals (Foerstephyllum)
stromatoporoids (Stromarocerium)
echinoderm fragments
straight-shelled nautiloid cephalopods (Actinoceras & Endoceras)
bryozoans (Eridotrypa)
rare brachiopods (Dalmanella & Strophomena)
rare coiled gastropods (Loxoplocus)
horizontal burrows of deposit feeders
How high was the energy of the environment in which the Watertown was deposited? The fact that the rock is micrite-dominated suggests that the environment was a quiet, low-energy one, generally incapable of transporting anything but fine to very fine grains. How, then, do we explain the abundant sand-sized bioclasts (which can be felt by rubbing a hand over a weathered surface - they feel like sand scattered in a nice coat of varnish)? Walker (1973) has suggested that most of the sand-sized bioclasts are porous echinoderm fragments. Porosity would reduce their densities and allow them to "behave" as smaller particles would in a current. Okay, but then how do we explain the very large fossil fragments, like the 3-meter-long nautiloids? Large fossil fragments can easily accumulate in a very fine-grained matrix if the animals lived on the bottom or died in the water column above and sank to the bottom. Currents are not required to move them to their sites of accumulation. One would expect that these large pieces might not be significantly abraded, although they may well be broken if someone had dined on the carcasses before they were buried. Lastly, how do we explain the presence of large chert nodules? It turns out that chert nodules are a secondary phenomenon and are formed in a sediment after deposition. Solutions rich in silica soak through the sediment and replace portions of the rock with silica, creating chert nodules. In a carbonate rock, it's not immediately obvious where the silica should come from. In the Black River Group, silica may have come from leached beds of volcanic ash or from solution of fragments of siliceous sponges. Volcanic ash is a good candidate, because thin volcanic ash layers blown from eruptions in the approaching Taconic Island Arc occur sporadically throughout the upper Black River Group.
What clues have emerged regarding the environment of deposition of the Watertown Formation? Fine grain size of the matrix points to a dominantly low-energy environment. Lack of mudcracks, intraclasts, and erosional intervals suggests that the bottom was always below low tide (a subtidal environment). Lack of deep burrowers supports this, suggesting that organisms did not need to burrow deeply to escape a hostile environment. The fauna consists of animals related to those in the Recent that require normal marine salinities (Walker, 1973) and prefer not to be bothered by daily tides. Modern calcareous algae require water depths of less than 80 m in clear water in order to photosynthesize, and Walker (1973) suggests that carbonate mud might have made the water turbid enough during deposition of the Watertown that 10 m might have been the maximum depth for photosynthesis. If we put this all together, we come up with an offshore shallow marine environment with good circulation and rare turbulence. The area would have normally been below wave base, but rare storms likely stirred up the bottom. The water would also likely have been warm, because central New York State was located about 20° south of the equator during the Ordovician. A pleasant place to live.
The limestones along the Sugar River display spectacular solution features, particularly in the massively-bedded Watertown Formation. One is first struck by the smooth, rounded, doughy-looking outcrops, and then by solution enlargement of joints, producing huge blocks of limestone along the streambed. Farther downstream, a magnificent train of potholes lines the stream channel, many containing pothole stones. Solution is as important as abrasion in creating these potholes. The most spectacular solution features, however, are the swallow holes. During a dry summer or fall, the Sugar River vanishes completely into swallow holes and never reaches the confluence with the Black River. However, during high water, a decrease in volume is difficult to see. Some of the lost water emerges as substantial springs along the face of the quarry. A look at the quarry face will suggest to you that the subsurface flow takes place through solution-enlarged joints, many along bedding surfaces, rather than through gigantic subterranean tunnels. DO NOT WALK TO THE EDGE OF THE QUARRY FACE- MUCH OF IT IS OVERHUNG AND UNSAFE. If you walk a short distance northeast, you will find the outlet for most of the swallowed Sugar River water- the Little Sugar River heads in a spectacular blind valley just easy of the quarry. The blind valley shows up well on the topographic map.
Glacial erratics dot the Black River Valley, and there is a very large granitic gneiss erratic smack in the middle of the Sugar River channel. The Sugar River probably makes headway in moving it about once every 200 years or so. (By the by, why aren't there any glacial striae on the bedrock at the Sugar River??)

STOP 6. LOWER TRENTON GROUP, SUGAR RIVER
The fine-grained, fossiliferous limestones and interlayered shales in this outcrop are part of the lower portion of the Trenton Group (Plate I) and were deposited in shallow Middle Ordovician seas at a time when the Taconic Island Arc Terrane had just begun to collide with the continental margin of North America.
The lower 2/3 of the outcrop belongs to the Napanee Limestone, the upper 1/3 to the Kings Falls Limestone. Both are part of the Trenton Group. Geologists who have studied the Trenton have chosen to divide the sequence into a total of 6 formations, only 2 of which are exposed here, and it is interesting to consider why they have done so and on what basis. Rock sequences are divided into formations within which rock types show some degree of internal homogeneity or sequence that distinguishes them from adjacent sequences. Some genetic connotation is implied, and one generally views the conditions or range of conditions of formation for a particular formation to be different from those in adjacent units. If they weren't, they'd all be part of the same formation. Formations must also be thick enough to be mappable at a reasonable scale. Some formation boundaries are obvious. For instance, there is a conspicuous difference between the Napanee Limestone and the Watertown Formation, which we just visited. Anyone would put them into different formations. However, we did not see the upper Watertown or lower Napanee. If they grade into one another, you might not place the formation boundary at the same place I would, and there's nothing wrong with that. Other formational boundaries are not so obvious. Take the one in this outcrop, for instance. The formation boundary between the Napanee below and the Kings Falls above separates thinly interbedded limestones and shales from thickly interbedded limestones and shales. One's first reaction is that there's not that much difference between the 2 units and that it all ought to be one formation. But, when we examine the details, we find that the limestone in the Napanee is dominantly very fine grained and sparsely fossiliferous, while the limestone in the Kings Falls is coarse and very fossiliferous. The subtle change in thickness of beds also marks a change in the environment of deposition, and it does make sense to place a formation boundary between the two.
The limestones in the Napanee are primarily sparsely fossiliferous micrites composed dominantly of carbonate mud (some pelletal) with infrequent, discontinuous skeletal laminae. There are some highly fossiliferous micrites (biomicrites), with many fossils and fossil fragments set in a carbonate mud matrix, and rare biopelmicrites, a fossil and pellet hash cemented by secondary calcite. The limestones are interlayered with black, sparsely-fossiliferous calcareous shales. In general, the coarser, fossiliferous limestones increase in abundance upward (Cameron et al., 1972). The coarser layers show some ripples and cross-stratification, but none of the layers contains mudcracks. The limestones display some vertical burrows, but they are not thoroughly burrow-mottled, as the Watertown Formation is.
In contrast, limestones in the Kings Falls are primarily shelly limestones and fossil hashes; matrix material is dominantly sparry rather than micritic. These limestones are referred to as biosparites or shelly calcarenties. Layers of thinly bedded calcareous shale alternate with layers of limestone, as they do in the Napanee, but limestone layers are considerably thicker in the Kings Falls than in the Napanee. Limestones in the Kings Falls show abundant high energy features, including cross-stratification, ripples, erosional surfaces, intraclasts, and an absence of micritic material (Titus and Cameron, 1976). These limestones accumulated as a collection of fossil fragments in an environment that winnowed out carbonate mud; spaces between fossil fragments were later filled with secondary, coarsely crystalline (sparry) calcite. A close look at a talus block from one of the Kings Falls layers will show you reflections from calcite cleavage surfaces 1 mm or more across - these are calcite grains of the secondary sparry matrix.
The fauna is brachiopod-dominated - about 1/3 of the species present are brachiopods (Titus, 1977). Fossils in the Napanee Limestone are illustrated in figure 8 and include:
brachiopods (friplesia, Da/manella, Sowerbyel/a, Rafinesquina, Strophomena, Paucicrura, Hesperorthis)
broyzoa (Prasopora, Stictopora, Amplexopora)
crinoid fragments
trilobites (Flexicalymene, Isotelus, Ceraurus)
snails - particularly in the lower Kings Falls (Sinuites, Liospira, Subulites, Hormotoma, Loxoplocus, Phragmolites)
ostracodes
coral - in the lower Kings Falls (Lambeophyllum)
The fauna in these 2 formations is dominated by low filter feeders (such as brachiopods and bryozoa), with some grazers (such as trilobites, gastropods, and ostracodes).
What clues have emerged regarding the environment of deposition of the Napanee and Kings Falls Limestones? The absence of mudcracks and other evidence of dessication in both formations, taken together with the abundant remains of marine organisms (few of whom could have managed a twice-daily low tide), suggest a subtidal environment. The dominance of sparry matrix in the Kings Falls and micritic matrix in the Napanee indicates that the Kings Falls was deposited in a high energy environment that winnowed carbonate mud, while the Napanee was deposited in a quieter environment that enabled carbonate mud to accumulate. However, presence of shaly laminae in the Kings Falls suggests that quiet water prevailed from time to time. The presence of cross-stratification, ripples, and erosional intervals, particularly in the Kings Falls, indicates that the environment was frequently above wave base. This conclusion is supported by the presence of fossil hash (coquina) layers, particularly in the Kings Falls. These layers are composed of disarticulated and broken skeletal materials, transported to the site of deposition by currents. Taken together, the evidence indicates deposition in shallow water, in a high subtidal environment The Napanee was probably deposited in a shallow, shelf-lagoon, while the coarse, sparry Kings Falls was deposited in a waveswept offshore shoal (Cameron et al., 1972; Titus and Cameron, 1976). Both were deposited in water shallower (or at least more agitated) than that characteristic of the Watertown Formation, which we just visited.
The repetitious interlayering of limestone and shale is an interesting puzzle. D.W. Larson (pers. comm., 1984) suggests that the interlayering is a storm-generated phenomenon, with the following scenario. Clay mixed with some carbonate may well have been the steady-state, everyday, slowly-accumulated sediment. The product would have been a calcareous clay mud deposited in a quiet-water environment incapable of transporting the silt-sized to coarse sand or pebble-sized carbonate grains and fossil fragments characteristic of the limestone layers. During storms, energy in the environment would have increased dramatically, bringing coarser carbonate detritus in from adjacent, higher-energy environments, and redistributing carbonate material previously deposited locally. The energy during storms would have been enough to winnow clays at the sediment/water interface, and carbonates of silt size or greater would have accumulated relatively rapidly. If you look carefully, you might even be able to convince yourself that some of the limestone layers in the Napanee are graded, with coarse fossil fragments decreasing in both abundance and size upward from the base of a layer.
In this scenario, the limestone layers represent relatively rapid, storm-related deposition. The rare, thin skeletal laminae within and at the top of limestone layers presumable contain fossils in or near life position and represent a community of organisms developed on the bottom after a storm. Storm-sequence deposition is illustrated in figure 8.
As one goes east in the Trenton Group, sediments record features of deeper water deposition. Here, too, limestones alternate with shales, but the limestones are very different in character. They show features that suggest deposition by turbidity currents in quite deep water. Earthquakes may well have shaken carbonate sediments lying on the shallow shelf to the west, mobilizing them into a great slurry that slid eastward just above the bottom. As the turbidity current slowed, layers of lime sands and muds settled out of the water, draped over the clay muds normally deposited in the environment.
Studies of features such as this tell us that the Trenton Group was deposited in sedimentary environments that ranged from low-energy lagoons to wave scoured barrier shoals, shallow and deep shelves, and a slope connecting the shelf to the west with a basin to the east. One shoreline appears to have lain well to the west of New York State. A shallow shelf extended as far east as the Black River Valley. East of there, water depths varied a surprising amount. Deep water changed to shallow water and back to deep water again several times between Utica and Albany. We think that indicates the presence of a number of fault blocks - horsts and grabens - in the transition wne from the western shelf to the eastern basin (Cisne et al., 1982; Kidd, 1991). The eastern shoreline of the basin lay approximately at the eastern border of New York State at the beginning of Trenton time.

STOP 7. WHETSTONE GULF
Throughout the region, the limestones and interlayered shales of the Trenton Group that we saw at Stops 5 and 6 are overlain by hundreds of meters of black Utica Shale (Plate 1). Over the past few thousand years, Whetstone Creek has carved a steep walled gorge into the very fine-grained, soft black shales and siltstones of the Utica Shale and overlying Whetstone Gulf siltstones and shales. The sediments are much finer grained than any others we will see today and were deposited in an environment little stirred by significant currents. The black color derives from abundant unoxidized organic matter, suggesting that the sediments were deposited in a putrid, anoxic environment incapable of oxidizing dead material as it settled quietly to the bottom of the sea. The Utica Shale in central New York State is considerably thicker (over 10X thicker!) than the earlier sediments we have examined, indicating that significant subsidence must have taken place in order to make room for such a thick accumulation of sediment. The muds accumulated in a basin estimated to have been as much as 500 meters deep, produced as the edge of the Laurentian continent foundered as it collided with the Taconic Island Arc.
The change in fossil assemblages is as striking as the change in rock types. The brachiopods, corals, bryozoans and trilobites that are so common in the Trenton Group and characteristic of well-aerated, warm, shallow waters are missing from the overlying shales. Instead, we find scattered remains of graptolites and trilobites preserved in a rock full of unoxidized organic material. Poor circulation in the deep basin produced an oxygen- and food-deficient environment that was highly charged with iron and poisoned by hydrogen sulfide. The water depths were so foul that no organisms lived there. All of the fossils are of organisms that were swimmers or floaters. Their remains evidently settled to the poisonous bottom when they died, and nothing was there to eat them.
Limestones of the Upper Trenton Group in the western part of the region were being deposited at the same time as the black shales in the Champlain Valley and central Mohawk Valley. If we were to look at a number of sections, we would see that the black shale environment gradually spread westward, until all of the Trenton limestones were blanketed by black muds derived by erosion of a high sediment source in the east
As the Ordovician drew to a close, the sediments changed yet again. The Utica Shale and Whetstone Gulf shales and siltstones are overlain by Pulaski and Oswego Fonnations (Plate I). It is these more resistant units that hold up the Tug Hill Plateau above Whetstone Gulf. There are many indications that water became progressively shallower in the Late Ordovician basin. Younger sediments are coarser in grain size, reflecting higher energy environments. The graptolite and trilobite-bearing Whetstone Gulf Formation is overlain by the Pulaski Sandstone, with abundant shallow-water marine clams and brachiopods. These are in turn overlain by the poorly-fossiliferous coarse beach sands of the Oswego Sandstone. The last units deposited during the Ordovician are not even marine - the basin had been completely filled in. The distinctive red shales siltstones, and sandstones of the Queenston Shale, remants of which cap the Tug Hill Plateau, show all the features of an enormous deltaic deposit that spread westward across the State.
While walking along the stream channel, notice that the shale and siltstone layers are strongly jointed. Also keep a sharp eye open for fossils in the talus and along the stream bed. Many cephalopods, brachiopods, trilobites, and graptolites can be found. Some of the cephalopods have been replaced by pyrite and look like tiny rolls of gold coins.

Good view of Pleistocene delta tops
Good view of Pleistocene delta tops to the northeast and southeast across the Black River Valley. If you look carefully, you can see sand and gravel quarries in the deltaic deposits. Notice how well these delta tops show up on the topo map.

Valley floor near head of Boonville Gorge.

Sand quarry in Pleistocene meltwater deposits.

Channel narrows into Gorge
Channel narrows into Gorge, where Pleistocene meltwaters were channeled into Lansing Kill. This was the outlet for glacial Lake Port Leyden, and the topographic feature is known as a meltwater channel. Boonville Gorge was cut by meltwaters relatively quickly during the Pleistocene and has been little modified since. The topo map on the next page shows the abandoned channel north of Lansing Kill and the knickpoint where the channel drops into Boonville Gorge.

View southward down steep-walled meltwater channel
Lansing Kill is now a small stream in a large, steep-sided valley.

Outcrop of Middle Ordovician Utica Shale
Outcrop of Middle Ordovician Utica Shale (the uppermost formation in the Trenton Group); the Pleistocene meltwater channel in Boonville Gorge was easily incised into the soft shales of the Utica.

Entrance to Pixley Falls State Park.

More Utica Shale.

Undercutting along meanders
For about 1 km, undercutting along meanders in Lansing Kill is well-developed.

Valley widens; erratic on floor to west of road.

Good view of Delta Lake.

Traversing floor of glacial Lake Iroquois
(before it dropped to the 450' elevation level).

Traversing glacial Lake Iroquois floor at Fort Stanwix.

Cross Barge Canal.

Upward from the floor of glacial Lake Iroquois
The road passes upward from the floor of glacial Lake Iroquois (at 450' level).

Kames or dissected esker in fields to east of road

Kame or esker remnant at Christmas Knob
Kame or esker remnant at Christmas Knob to north of the road. This feature shows up best during the winter when the leaves are off the trees.

Crossing filled Chenango Canal.

STOP 8. CLINTON IRON ORES
The sediments of the Clinton Group (Plate I) are a sequence of extremely varied clastic rocks deposited in nearshore marine environments during the Middle Silurian. Sources for the detritus lay to the east in the eroding highlands of the accreted Taconic Island Arc Terrane. At stop 7, we will have a look at spoil piles dumped during extraction of the Westmoreland Hematite, one of the 2 iron ore horizons in the Clinton Group.
The samples in the spoil piles are dominated by brownish-red calcareous oolitic hematite ore from the Westmoreland Hematite. The ooliths (pron. oh-oh-liths) are approximately 1 mm in diameter and range in shape from spheroids to oblate spheroids. The ooliths are composed of concentric layers of hematite and chamosite (an iron-silicate mineral) deposited around a nucleus, commonly a well-rounded quartz grain (Dale, 1953; Muskatt, 1972). Sliced in half, the ooliths resemble an old-fashioned fireball candy. Ooliths form when minerals precipitate chemically from seawater around a sand grain or fossil fragment nucleus. As currents roll the ooliths around on the bottom, they acquire layer upon layer of chemical precipitate, in snowball fashion. Calcite ooliths are currently forming on wave-agitated portions of the Bahama banks. In the Westmoreland Hematite, ooliths accumulated hematite instead of calcite. The ooliths are accompanied by rare fossil fragments and are set in a matrix of hematite, sparry calcite, and dolomite (Muskatt, 1972). In some layers, hydration has converted hematite to limonite or goethite, giving the layers an orange, rather than red-brown, color.
In addition to oolitic hematite, specimens in the spoil pile contain layers of gray-green siltstone (no ooliths), fossiliferous red shale (with some ooliths), fossiliferous and burrowed green shale, and sparsely oolitic layers with an abundance of rounded intraclasts and quartz fragments up to 1 cm across. Layers are lense-shaped and somewhat discontinuous. Some specimens show well-developed trough cross-stratification, and many of the oolitic hematites show hints of cross-stratification. Megaripples with a wavelength of about .5 m occur along the path east of the spoil pile.
Fossils include brachiopods, trilobites, cephalopods, ostracodes, crinoids, conularids, and traces of many burrowing organisms. Fossils from the Clinton Group are illustrated in figure 9.
What clues emerge concerning the environment of deposition of these units? Presence of cross-stratification, megaripples, coarse detrital particles, intraclasts, erosional intervals, and ooliths all point to a well-agitated environment for the rocks in which these features occur. Finer-grained lithologies demand a quieter environment, and, predictably, these are the lithologies with most of the animal remains and trace fossils. An area above wave base and perhaps occasionally above low tide level is consistent with both sediment types and fauna. Tidal flats, channels, and lagoons inter-fingering with one another seem to be a reasonable scenario for these rocks.
The hematite in these rocks is primary - it accumulated in the sediment right along with the clastic material. The most curious aspect of this, however, is the fact that the iron must have been in solution in the seawater in order for hematite to have precipitated and accumulated as ooliths. This may not seem like much of a problem; after all, seawater is a real soup of dissolved material. The problem is that, under oxidizing marine conditions, iron is extremely insoluble. (Salt water may rust your car, but, once it's rusted, sea water won't dissolve iron oxides off the rusty spots on your car.) Modern marine waters and most river waters contain very little dissolved iron, and there is no evidence to suggest that Middle Silurian seas were very must different overall.
So, what can make iron soluble? Iron dissolves in very acidic waters and very reducing waters; neutralize or oxidize such water, and the iron will precipitate out. Many workers have suggested that sedimentary iron ores such as the hematitic ores of the Westmoreland formed where hot or cold submarine springs debouched acidic and/or reducing water laden with dissolved iron. Upon mixing with normal marine water, iron oxides and silicates precipitated as ooliths or replaced calcite in fossil material (as in the Kirkland Hematite or "red flux") (Stanton, 1972).
Sedimentary ironstones like the Westmoreland and Kirkland ores are referred to all over the world as "Clinton-type ores", names for the Clinton Group and Clinton, New York. Clinton-type ores have been important sources of iron in the past, supporting such famous steel towns as Birmingham, Alabama. Ores in the Clinton, New York area were exploited as early as 1797, and active mining of ore for pig iron continued until the end of World War I (Dale, 1953). As the huge easily-extractable ores of the Lake Superior Iron Ranges were developed during World War I, mine owners found it less and less profitable to extract ore from the 1-2 m-thick hematite layers in Clinton. After World War I, iron ore was extracted for paint and brick pigment only. The operations at Stop 7 were run by the Clinton Metallic Paint Company, and workings were entirely underground. Operations began on Brimfield Street in 1928 and shut down in 1963. The map in figure 9 shows the areas of Clinton undermined by iron ore extraction. Many claim that these underground workings have adversely affected groundwater flow in this area.

Bridge over Dawes Creek.
Herkimer Sandstone (Clinton Group) crops out east of the bridge. Megaripples of two different orientations grace the bedding surfaces along the creek.

STOP 9. EASTERN ROCK PRODUCTS QUARRY, ORISKANY FALLS
At this stop, we will be interested primarily in glacial features exposed at the rim of the quarry. However, we will have a look at the bedrock if time permits.
Portions of 5 Devonian formations are exposed in the quarry. The lower 35 m of gray limestones belong to the Helderberg Group, including 12-15 m of the Manlius Formation, 15 m of the Coeymans Formation, and 2 m of the Kalkberg Formation. 3 m of white Oriskany Sandstone forms the prominent band high on the quarry face above the gray Helderberg. 20 m of gray Onondaga Limestones at the top of the quarry face is overlain by glacial tills of variable thickness. All of the bedrock units were deposited in shallow epicontinental seas during the Early Devonian, after substantial erosion of the accreted Taconic Island Arc Terrane, and prior to accretion of the Avalon Terrane. In a trip eastward from the ocean here at Oriskany Falls during the Early Devonian, one would have encountered a low, broad landmass in what is now New England, more ocean (this time a real ocean basin with oceanic crust), and, finally, the small continent of Avalon.
The Helderberg limestones are a varied lot. Differences in lithology reflect differences in environment of deposition. Carbonate mud matrix in some reflects relatively low energy environments, while sparry matrix in others suggests high energy. Mudcracks show dessication in some, but not all units. Some of the limestones are cross-stratified and were deposited above wave base; others show evidence for being affected by waves only during storms.
The Manlius shows features consistent with environments oscillating between supratidal, intertidal, and shallow subtidal lagoon environments. Walker and Laporte (1970) have suggested that good analogies may be drawn between these limestones and their environments of deposition and those in the early Middle Ordovician Black River Group. The organisms in the communities are, of course, different species, but they occupy similar nitches in strikingly similar rocks.
Water deepened episodically but progressively during deposition of the Helderberg. The Coeymans Formation was deposited on a discontinuous barrier shoal in environments that ranged from high to low energy, and the Kalkberg was deposited in a shallow, open marine environment dominantly below wave base (Laporte, 1969; Walker and Laporte, 1970).
The Oriskany Sandstone lies disconformably on the Helderberg Limestone and represents a shoreline sand sequence deposited at the base of the last transgressive sequence in the Early Devonian. These sandstones are coarse-grained and contain remains of enormous brachiopods. Evidently, the energy in the environment was either too high to preserve more delicate fossils, or else was too high to allow less robust organisms to live happily. In southwest New York State, the Oriskany Sandstone is hundreds of meters below the surface and serves as a good reservoir rock for petroleum.
The lower Onondaga Limestone is chertier and coarser-grained than much of the Helderberg Group, but individual pieces on the quarry floor are difficult to distinguish from the gray limestones of the Helderberg. Environments during deposition of the Onondaga were primarily those on wave-affected, shallowly-submerged lagoonal shelves (Lindemann, 1979). Reefs are common and are known to contain natural gas. The Onondaga has been used extensively for building stone, and, obviously, is quarried for aggregate.
At the top of the Devonian sediments in this quarry, we find a very distinctive erosion surface that shows conspicuous evidence of glaciation. If you examine the limestone carefully, you will be able to find examples of striae, crescentic gouges, and chatter marks. The pebbles, cobbles, and boulders that were stuck in the underside of the ice or pressed between ice and rock acted like sandpaper, forming the scratches, grooves, and gouges. Friction between the pebbles and the bedrock caused the pebbles to jump like chalk on a blackboard, forming chatter marks. Direction of striae indicate that this area was overridden both by south-flowing ice from the Laurentide ice sheet and by southeastward-flowing ice from the Ontario lobe.
Unsorted, unstratified glacial till overlies the Devonian rocks and makes up the overburden in this quarry. The till is removed and used by local municipalities as fill. In the unstratified till, you can see the direct contact of lodgement till (ground moraine) with the underlying bedrock. In some of the overburden, areas of stratification occur, where meltwater poured off the ridge to the northeast onto or along the ice sheet that filled the valley.

A7: SEDIMENTATION-EROSION PATTERNS ALONG THE SOUTHEASTERN SHORELINE OF LAKE ONTARIO
Paul R. Pinet
Charles E. McClennen
Colgate University
Hamilton, N.Y. 13346
Bruce C. Frederick
RSMAS, University of Miami
Miami, FL 33149
Introduction
The southeastern shoreline of Lake Ontario (Fig. 1) is dynamic and evolving rapidly in response to wave conditions, rainfall patterns, groundwater seepage, and short- and long-term variations in lake levels. We have been studying these changes in a systematic way for three years, trying to document the nature of these processess as they interact to produce depositional-erosional effects. The field trip is designed to acquaint you with the results of our work and to show those of you who are in academia the potential this area has for field instruction about glacial and coastal deposits and processes. Furthermore, we hope that some of you may opt to direct your research efforts to some of the many unsolved problems that we will be discussing during the trip.

STOP 1. McIntyre's Bluff
Here we will walk about one kilometer of the shoreline, examining in detail the gullies that are carved into Mclntyres Bluff, the cobble beach fronting the bluff, and a baymouth barrier in front of Juniper Pond.

STOP 2. Little Sodus Bay
Here we will study the impact of shoreline-stabilization projects on erosional-depositional patterns of the adjoining shorelines.

B1: QUANTITATIVE PALEOECOLOGY OF HAMILTON GROUP LOCALITIES IN CENTRAL NEW YORK
Willis B. Newman, James C. Brower, and Cathryn R. Newton
Syracuse University,
The Middle Devonian Hamilton Group has in recent years attracted much interest, including studies published in two volumes edited by Brett (1986) and Landing and Brett (1991). Transgressive and regressive cycles are a prominent feature of the marine sediments (e.g., Brett and Baird, 1985; Brett, Baird and Miller, 1986). The thin cycles in western New York consist of shale, calcareous shale, and limestone and are roughly symmetrical (Miller, 1986; Savarese, Gray and Brett, 1986). Approaching the source area in eastern New York, the cycles become thicker and are dominated by a regressive phase of mostly fine and coarse clastics.
This paper reviews the paleoecology of six typical regressive cycles in central New York based on quantitative multivariate techniques. The work is preliminary and more detailed studies are in preparation. Although Hamilton communities and paleoecology have been the subject of a legion of papers, most of these are qualitative. Examples can be found in the Hamilton volumes mentioned above. Papers emphasizing quantitative methods in the study of Hamilton communities include Brower (1987), Brower and Kile (1988), Brower, Thomson and Kile (1988), and Brower and Nye (1991). Other works using quantitative techniques, mostly cluster analysis, are Miller (1986), Savarese, Gray and Brett (1986) and McCollum (1991). Our analytical strategy operates in a series of steps. In the flrst stage, communities and gradients are characterized by means of various clustering and ordination algorithms. Both types of techniques are necessary because they are subject to different forms of distortion and they show different structures in the data set. The communities and gradients are tested for statistical significance through a variety of approaches. Both communities and gradients are then analyzed in terms of parameters such as diversity, equitability, and trophic structure. Finally, the causal factors that generated the sequence of communities and gradients are determined.
SUMMARY AND CONCLUSIONS
During this study, six typical cycles of upwardly coarsening clastic sediments have been examined in the Hamilton Group of central New York. Sedimentary sequences were selected from the Marcellus, Skaneateles, and Ludlowville Formations which represent the lower and upper parts of the group. Closely-spaced and large samples, mostly composed of 300 or 1000 specimens, were taken in order to characterize faunal diversity, proportions and ecological structure. The following conclusions are drawn:
1. Samples of 300 specimens are large enough to characterize the most diverse Hamilton communities in this area.
2. The main pattern in all cycles consists of decreasing depth and correlated differences as evidenced by change in sediment grain size, sedimentary structures, amount of organic matter, and faunal composition.
3. The multivariate techniques of cluster analysis and correspondence analysis are successful in the identification of faunal communities or assemblages. They also point to relations between and within communities. The ordination method of correspondence analysis and the clustering algorithms produce complimentary data, and both types of techniques should be employed in concert. Once the analyses are complete, it will be possible to specify average composition and variances for the various communities.
4. Statistical significance tests at the 0.05 probability level have been performed on all pairs of related communities as ascertained from the correspondence analysis plots and the known vertical sequences of communities. As expected, the multivariate means of all communities are statistically different, and all communities differ in average composition. Significance tests on clusters were also employed on the data to test the amounts of overlap in the populations from which the samples were derived. In two locations, Route 20 and Cascade, most or all of the communities comprise samples from rectangular distributions that do not overlap along the observed faunal gradients. These communities seem to have been tightly structured. At the other outcrops, Swamp Road, Cheese Factory Gulf, and Road #4, the pairs of communities come from populations that are characterized by overlapping rectangular distributions. In fact, the parent populations may exhibit as much as 50 percent of overlap (calculated for Gaussian or normal distributions) although lower percentages are more typical. Widely overlapping communities are deemed to be weakly structured and, perhaps, poorly integrated. The significance tests are still being explored.
5. The scores for the samples along the first correspondence axis extract the main pattern of change and relations between the communities for each outcrop and cycle treated. As mentioned previously, the cycles were probably produced by decreasing depth or shoaling, so these scores yield a generalized measure of relative depth. The exact relation between the first correspondence axis and depth cannot be specified at present, and the relationship could be rank order, linear or nonlinear.

B1: QUANTITATIVE PALEOECOLOGY OF HAMILTON GROUP LOCALITIES IN CENTRAL NEW YORK

STOP 1. ROADCUT ON SWAMP ROAD
This outcrop exposes about 20 m of the upper part of the Pecksport Member of the Marcellus Formation (Grasso, Brett, and Baird, 1985). The dark grey shales at the base grade into fine grey to brown coarse siltstones at the top (Fig. 1). Moving upwards, there is a gradual increase in species richness, adult size of the different species, proportion of epifaunal taxa, and a decrease in the abundance of deeper water taxa like Leiorhynchus and Pterochaenia.
The exceptional preservation of calcite and aragonite shells at this locality has been the focus of many studies, for example Bailey (1983) on bivalves, Rollins, Eldredge and Spiller (1971) on gastropods and monoplacophorans, Cameron (1967) on a uniquely preserved annelid worm, and Carter and Tevesz ( 1978) on the shell microstructure of various groups.
On initial qualitative examination, we recognized a Leiorhynchus-nuculid dominated community at the base, grading into a Mucrospirifer dominated assemblage in the middle which was capped by a large clam fauna at the top. Selleck and Linsley (1989) reported that "the fauna is dominated by the brachiopods Spinocyrtia in the upper sandier facies, and Mucrospirifer in the middle siltier layers, along with the bivalves Ptychopteria flabellum, Gosseletia triquetra and a variety of nuculids, gastropods including Bembexia sulcomarginata and Palaeozygopleura harniltoniae plus a variety of orthoconic cephalopods", which is also a fair qualitative statement. The preservation is deceiving. Many of the taxa possess well preserved intact or nearly intact shells composed of black calcite; these weather out and attract much attention as one searches for fossils.
More detailed sampling and quantitative analysis produces different results. The study examined 37 samples, spaced at 0.5 m intervals, consisting of 300 specimens each for a total of 11,100 individual fossils and found a very different picture. Mucrospirifer mucronatus ranges from 0 to 30 percent in any sample and does not dominate a single sample. Gosseletia triquetra yielded only 26 specimens and comprised less than 2 percent of any sample in which it was present. Spinocyrtia granulosa ranged from 0 to 4 percent of the samples. Leiorhynchus multicostum does dominate many of the lower samples found in dark shales, but Devonochonetes scitulus and Ambocoelia umbonata are more common in the higher samples.

STOP 2. Rockslide And Gully In Cheese Factory Gulf
The dark grey and silty shales at this outcrop are assigned to the upper part of the Cardiff Member of the Marcellus Formation (Fig. 5). In general, it represents a more distal equivalent to the upwardly-coarsening sequence seen at Swamp Road. The most interesting aspect about this sequence is that it records the establishment of a stable benthic fauna in an area previously dominated by sparse pelagic taxa such as orthocones and Pterochaenia fragilis. As noted by Brower and Nye (1991), some individuals of Pterocbaenia were probably epiplanktonic whereas others were most likely byssally attached to the substrate.
This part of the section is not generally well exposed because the soft shales weather rapidly and are quickly overgrown. The two exposures here allow comparison of weathered and fresh outcrops. The slide section dates from the early 1970's whereas the ravine developed during the summer of 1990.
The study was conducted on 35 samples taken from the ravine at 0.5 meter intervals (Fig. 5). Approximately 10,500 fossils were counted. Five depauperate samples at the base of the ravine were omitted from the analysis because it was not possible to count 300 specimens.

STOP 3. Roadcut On Route 20 Near Pompey Center
The Route 20 roadcut exposes the Delphi Station Member of the Skaneateles Formation except for the basal and topmost beds. Brower, Thomson and Kile (1988) published a detailed description of this outcrop. Seventy samples were obtained from the section which ranges from shale at the base to fine siltstone and sandstone at the top (Figure 9). The cluster (Figs. 10 a & b) and correspondence (Fig. 11) analyses reveal three communities, Nuculoidea, Schuchenella, and Actinopteria, listed in ascending stratigraphic order. The Nuculoidea community can be divided into three subcommunities. Significance tests on the clusters suggest that they are relatively tightly structured. All assemblages found in adjacent beds represent samples that were drawn from disjunct rectangular distributions at the 0.05 or 0.01 risk levels.
All three communities have equitabilities that are 0.78 or higher and are interpreted as biologicallyy accommodated rather than opportunistic. For example, Brower and Nye (1991) report equitabilities ranging from 0.19 to 0.49 for three Hamilton benthic communities that formed under stressed conditions. Proceeding from the Nuculoidea to Schuchertella to the Actinopteria community, the grain size becomes coarser, ranging from mainly shale to mostly siltstone and sandstone, whereas the organic content decreases from 3.01 to 2.11 percent The number of common taxa per sample rises from about 16 to 23. The lithology and sedimentary structures demonstrate that the Nuculoidea community occupied the deeper and more offshore areas whereas the Actinopteria assemblage lived in the most shallow regions closer to the shoreline.

STOP 4. Private Quarry On Road Number 4 East
About 12.5 m of the lowermost part of the Otisco Member of the Ludlowville Formation is present at this stop (Fig. 13). The lithologies range from shale to fine-grained sandstone and the organic matter content varies from 3.0 percent in some of the shales to 1.2 percent in the uppermost sandstone. Examination of the lithology indicates that three upwardly-coarsening cycles can be seen; the tops of these cycles are at roughly 4 m, 7 m and 12.5 m. Each cycle begins with shale; the two lower cycles are capped by a siltstone that contains abundant Zoophycos caudagalli trace fossils, whereas the upper one ends in sandstone containing a large brachiopod and bivalve fauna.
Three faunal associations were initially apparent in qualitative field studies: 1) A Devonochonetes association characterized by infaunal, deposit-feeding bivalves, gastropods, and abundant Devonochonetes scitulus. 2) A Mucrospirifer association containing a higher diversity fauna of semi-infaunal and epifaunal brachiopods and bivalves. 3) A Protoleptostrophia association dominated by large reclining brachiopods and bivalves. However, this is rather misleading. As in the case of the Swamp Road, the multivariate analyses based on clustering and correspondence analysis reveals a slightly different paleoecological structure.
Large samples were taken -- each sample consists of 1000 individuals in order to study the effects of sample size on faunal diversity and proportions. These results suggest that a sample size of 300 individuals is adequate to characterize these parameters for most diverse Hamilton Group communities. The 54 samples are distributed throughout the stratigraphic section (Fig. 13).

STOP 5. Roadcut On Route 38 At Cascade
Two asymmetrical cycles which coarsen upwards were sampled at this outcrop; an upper one in the Ivy Point Member of the Ludlowville Formation (Fig. 17a) and a lower one in the Otisco Member (Fig. 17b). Brett, Baird and Miller (1986) published a complete stratigraphic section for this roadcut. The two cycles were selected because large areas were available for sampling which contain representative samples of the overall fauna A variety of lithologies are present which vary from dark grey shale with fine laminations and comparatively high amounts of organic matter to fine grey siltstones where organics are relatively sparse. Three hundred fossils were counted in each sample. Inasmuch as only 24 and 16 samples were collected from the lower and upper cycles, respectively, they were amalgamated to give a larger data set with 40 samples. In contrast to the other outcrops examined, two sources of variation reside in the data, namely changes within the cycles as well as contrasts between them.

B2: THE LITTLE FALLS DOLOSTONE (LATE CAMBRIAN) : STRATIGRAPHY AND MINERALOGY
Herman S. Muskatt
Victor P. Tollerton, Jr.
Utica College Of Syracuse University
Utica, New York 13502
The Late Cambrian Little Falls Dolostone is well known for the occurrence of exceptionally clear, doubly terminated quartz crystals, known as "diamonds", and for the irregular hemispherical masses of algal stromatolites, known as "cryptozoons". The areal relations of the Little Falls Dolostone in the field trip area is shown in Figure 1.

B2: THE LITTLE FALLS DOLOSTONE (LATE CAMBRIAN) : STRATIGRAPHY AND MINERALOGY

Ilion Gorge and Steele Creek
This section of road, known as Ilion Gorge, is somewhat narrow and quite winding. The road follows Steele Creek.

Syracuse Fm. (Upper Silurian).
Outcrop (on the right) of gray Syracuse Fm. (Upper Silurian).

Vernon Shale (Upper Silurian)
Outcrop of the red Vernon Shale (Upper Silurian). See Treesh, 1972, for more details. These exposures of the Vernon Shale continue for the next 0.3 mile.

Junction of Route 51 with Jerusalem Hill Road
This section of Jerusalem Hill Road is closed. See Treesh (1972) for more details on the units exposed along this closed road. Continue north on Route 51.

Otsquago Sandstone and Tornado Damage
Short stop. Pull off CAREFULLY to the very wide shoulder on the left . Two items of interest. 1) is the small 15' thick outcrop of Otsquago Sandstone (Middle Silurian, Clinton Group; see Muskatt, 1972, for more details). 2) is the damage to trees caused by a tornado in the late 1980's (1989?).

Bridge over Steele Creek. Oneida Conglomerate
On the left, in the stream, are thick layers of the Oneida Conglomerate (Middle Silurian, Clinton Group; see Muskatt, 1972, for more details).

Historical marker on the right
Historical marker on the right, to mark the place where Eliphalet Remington 2nd made the first Remington gun.

Exposures of Frankfort Shale (Upper Middle Ordovician).
These road cut and stream bank exposures on the left and right, continue for 1.4 miles.

Exposure of glacial fluvial deposit in a sand and gravel pit.

Levee system to right
Behind the houses on the right is the levee system for flood control of the West Canada Creek.

Small exposure of the Dolgeville Fm (Middle Ordovician) on the left.

Abandoned stream meander
On the left for 0.4 mile is an abandoned stream meander of West Canada Creek. The stream channel was diverted by the DOT. Note also the braided nature of West Canada Creek as it tries to adjust to the changes.

Undercutting of glacial material
On the right in the hillside, note the undercutting of the glacial material by a meander of West Canada Creek.

Herkimer Diamond Mines
On the left is one of two commercial collecting localities for the quartz crystals known as "Herkimer Diamonds".

Ace of Diamonds Mine
This is the second commercial site for "Herkimer Diamonds". Note also the exposure of the Little Falls Dolostone (Upper Cambrian) on the left.

Glacial Kame deposit and striations
On the left is a large exposure of a glacial kame deposit. Also of note are the glacial striations on an exposure Precambrian syenite gneiss.

Precambrian syenite gneiss
On the left is another exposure of the Precambrian syenite gneiss. These two exposures are part of an uplifted block of Precambrian bedrock. It is similar to the material exposed on Moss Island (see Muskatt, 1978, for more details). Note also the nonconformable contact of over 1 billion years.

Bridge over West Canada Creek.

Eastern Rock Products, Inc. Quarry.
Entrance on the left for the Eastern Rock Products, Inc. Quarry. Park here. We will be crossing the road (on foot) to enter the quarry. There are no further field stops, and you may leave at your leisure. PLEASE, stay away from the water-filled areas, and DO NOT CLIMB THE QUARRY WALLS.

B3: LATE PLEISTOCENE MELTWATER DRAINAGE THROUGH CENTRAL NEW YORK
Bryce M. Hand
Department of Geology, Syracuse University
When the retreating margin of Wisconsinan ice last stood in central New York, large quantities of meltwater poured eastward across uplands separating north-south valleys occupied by finger lakes. In some places, these ancient meltwater routes are inconspicuous; more commonly, they are impressive gorges produced by vertical incision or waterfall migration. On this trip we will examine channels, waterfalls, dry finger lakes, and remnants of deltas produced during this phase of deglaciation.
The importance of meltwater in the deglacial history of central New York has been recognized for many years. Fairchild (1909; 1932) mapped channel complexes from Batavia to Oneida, relating them to discharge from preglacial lakes north of the Valley Heads moraine (which today dams the southern ends of Seneca, Cayuga, and other Finger Lakes), and to "Great Lakes" flow from the Lake Erie basin and beyond. Sissons (1960) described meltwater scour features and sedimentary deposits between Syracuse and Oneida, and demonstrated that englacial, subglacial, and supraglacial flow were locally important. (These types of flow undoubtedly occurred in our area, but ice-marginal drainage was paramount.) Krall (1966) studied fluvioglacial drainage features in the region between Skaneateles and Syracuse. Other discussions bearing on the Syracuse channels have appeared in guidebooks of the New York State Geological Association (Muller, 1964; Grasso, 1970; Hand and Muller, 1972; Hand, 1978).
Despite the remarkable record of meltwater events displayed in central New York, complete historical reconstruction may never be possible. Lack of continuity is a problem; channels traversing upland regions are interrupted by north-south "through" valleys that held lakes (or ice) when the channels were active. Moreover, many erosional features are products of multiple episodes of ice advance and retreat, each accompanied by meltwater drainage that may or may not have been similar to drainage during other episodes. Constructional features (deltas) are temporally more coherent, in that they all must be products of the final phase of ice withdrawal. However, as drainage patterns evolved in response to changing lake levels or the opening of new escape routes, deltas have been destroyed or modified to the point where their significance is not always clear. Finally, the ever-changing configuration of the ice margin (which often provided one bank for the meltwater stream ) is not well constrained.
The point of this trip is to observe a Whitman's Sampler of the types of evidence that remain. Hopefully, ambiguities generated by the inadequate record will be compensated by the fun of weighing alternatives and identifying fatal flaws in our colleagues' (and your leader's) interpretations.

B3: LATE PLEISTOCENE MELTWATER DRAINAGE THROUGH CENTRAL NEW YORK

Start

STOP 1 Rest Area
View across Tully valley segment of Onondaga valley. This is the southward-directed "stem" of the Y-shaped trough ("through valley") system that will be the focus of this trip; Cedarvale trough can be seen extending northwestward from the three-way junction, but the northeastward continuation of Onondaga valley (toward Syracuse) is not visible from here.
As Wisconsinan ice retreated from the Valley Heads moraine (Tully moraine segment, four miles south of here), proglacial Lake Cardiff was impounded between the moraine and the receding ice front. Initial drainage was southward across the Tully moraine (1200') to the Susquehanna River. Later escape was westward (through Joshua and Navarino Channels) into adjacent lakes controlled by slightly lower segments of Valley Heads moraine.
The focus of this trip, however, will be on still later phases of drainage, corresponding to ice-front positions within about 4 miles of downtown Syracuse (and lake levels below about 900'), when meltwater from as far west as Lake Huron poured through central New York. It was this flow that scoured the Split Rock channels, Pumpkin Hollow, "Syracuse" channels (the several outlets crossing the upland between Onondaga and Butternut valleys), and other prominent canyons across uplands farther east and west.

Crest of moraine
The road follows the crest of the Tully moraine. This is predominantly a kame moraine, composed chiefly of outwash. Irregular topography is due to kettles and (to a lesser extent) channeling.

STOP 2. Hidden Falls Road
Excellent view of the north (proximal ) face of Tully moraine. This steep face, which was banked against the ice, contrasts with the gently sloping (kettled) topography south of the moraine crest. This is the plug that held a lake in Onondaga valley.
Crest of the moraine stands at 1200 ' ; 2 miles north of here, the valley floor is 600' lower. Several hundred feet of unconsolidated valley fill (till, outwash, lake clays, and postglacial alluvium) occur even in the deeper parts of the valley.
Rounded gravels in the roadside exposures are typical of the kame materials making up the bulk of the moraine. Clasts of local bedrock predominate : Lower Devonian limestones and dolostones are especially abundant; brown siltstones from the Hamilton Group are somewhat underrepresented, because they are less durable. Somewhat farther-traveled are red Medina sandstone and white Potsdam(?) sandstone. Gneisses come from the Canadian shield.

Delta remnants
Shortly after turning onto US 20, observe delta remnants in Cedarvale trough. The flat tops of these remnants represent various lake levels.

Navarino Channel
Road descends into and crosses Navarino channel. The lake in Cedarvale/Onondaga valley discharged for a while through this channel, which held lake level at just over 1000'. To the southwest (downstream), Navarino channel terminates in a small delta on the east wall of Otisco valley.

STOP 3 Marcellus Town Dump
This is the entrance to Pumpkin Hollow, easily the largest and most impressive meltwater cross channel in central New York. Carved in Marcellus (black) Shale, Pumpkin Hollow is over 300 ft deep, 500 to 1500 ft wide at the floor, and 3 mi long. It carried Great Lakes drainage from Otisco valley to the head of Cedarvale trough. (Virtually all of this flow had previously entered Otisco valley through Guppy Gulph. )
We have here clear evidence that retreat of Pleistocene ice from the Valley Heads position was interrupted by at least one brief readvance. Three miles north of Pumpkin Hollow begins a group of cross channels and scourways collectively called the "Split Rock series." Many of these scourways are one-sided, implying that the other bank was the ice itself, and that the axis of flow shifted laterally (northward) as the ice retreated. Like pumpkin Hollow, the Split Rock series carried substantial throughput from farther west, probably including outflow from an early phase of Lake Warren.
The highest of the Split Rock series stands at about 900', whereas Pumpkin Hollow is excavated to 700'. Clearly, Pumpkin Hollow could not have been open when the Split Rock series was active, because drainage would simply have escaped via the lower (Pumpkin Hollow) route. Moreover, incision of Pumpkin Hollow after ice had withdrawn far enough to permit development of the Split Rock series requires readvance to >=900' to initiate cutting of Pumpkin Hollow.
If, as suggested by Calkin and Muller (1992, pers. comm.), the Valley Heads moraine represents the Port Bruce Stade (=14,000 Ka), the Split Rock series is reasonably assigned to ice retreat during the Mackinaw Interstade, and readvance (activating Pumpkin Hollow) to the Port Huron Stade (=13 Ka).
It is not known how far the ice front retreated during the Mackinaw Interstade. It could well have cleared the northern margin of the Appalachian Plateau, permitting an interval of "free drainage" (Erie channel?), as envision ed by Fairchild. The limit of Port Huron readvance is probably defined by the end moraine (eastern equivalent of Auburn/Geneva/Canandaigua moraines) about 2 mi south of Pumpkin Hollow.
Although the Split Rock series is usually envisioned as the product of ice recession, it is probably equally valid to view it in the context of ice readvance. The flow is then seen as being pushed progressively southward and to higher elevations, until (somewhat above 900') it was either stopped or redirected to Pumpkin Hollow.
Disappearing Lake, in the west end of pumpkin Hollow, occupies a shallow basin in the top of the Onondaga Limestone. If time permits, we may consider the origin of this depression and some of the lake's interesting behavior.

Driving through Pumpkin Hollow
After about 2 mi, the valley suddenly widens as the north slope recedes. Krall (1966) has shown that Cedarvale trough once continued northwest (i.e., into the north wall of the valley ), but became filled with till and was not subsequently reexcavated. A well along Seneca Tpk (NY 175) a mile northwest of here (el. 1030') penetrated 200+ ft of drift without encountering bedrock.

Delta Remnants
Road climbs onto remnants of deltas deposited by flow that entered the lake in Cedarvale trough after being discharged from Pumpkin Hollow. Delta sands and gravels are underlain by pink lake clays that can be seen here in the roadside ditch, the gully along old dirt road leading to gravel pit on right, and in a bank on left side of road.

Crossing Delta Surfaces
Crossing delta surfaces at 720', 660', and 600'. All of these deposits relate to flow from Pumpkin Hollow. (Some higher levels, above 780', appear to be scoured till surfaces and small kame deltas from local drainage.) Early (high) deltas were eroded and their materials (in part) redistributed into lower deltas as the lake level fell. Note well preserved distributary channels.

STOP 4 Saunders & Sons Gravel Pit
(PERMISSION REQUIRED)
Sand and gravel are being extracted from the Gilbert-style delta whose topset beds define the 720' and 780' levels. Angle-of-repose foresets dip down-valley (ESE) in a single spectacular set whose thickness reaches 70' or more.
Lake level for the 780' delta was probably controlled by the 770' threshold of the approach to Clark Reservation channel. The 720' delta probably formed after the lake outlet had shifted to the (700') threshold of Nottingham Road channel.
Delta deposits in Cedarvale trough must have formed during the final retreat of ice. Had they formed earlier, they would have been vulnerable to destruction or drastic alteration during subsequent ice advance. Also, it was not until final deglaciation that flow through Pumpkin Hollow became established (recall discussion at Stop 3).
The clast composition of these gravels (pebbles/cobbles of limestone, dolostone, red Medina sandstone, gneiss) indicates derivation overwhelmingly from glacial drift. Pumpkin Hollow, which provided the flow that built the delta, is cut in Marcellus (black) Shale, but there are few, if any, clasts of black shale in this pit. This suggests that Pumpkin Hollow first formed in pre-Port Bruce time, became filled with drift during a subsequent glacial advance, and remained filled until final deglaciation (retreat from the Port Huron posItion). Excavation of the modern gorge would have begun with removal of this drift and its incorporation into the Cedarvale deltas.
The alternative possibility, that pebbles of Marcellus Shale would not survive transport, is rejected because such clasts are very abundant in the extensive 620' delta deposits even farther from source. These shale-rich deposits prove that some deepening of Pumpkin Hollow occurred through bedrock erosion during deposition of the youngest (and lowest) deltas. Even the low delta gravels consist chiefly of "bright" (recycled drift) clasts, most of which were probably reworked from older deltas .

620' Delta Terrace
Driving on 620' delta terrace, which displays many well preserved distributary channels. The delta prograded southeastward, down Cedarvale trough to the 3-way junction of the "Y"-shaped valley system, then northeastward toward Syracuse. Further progradation into the Tully valley "stem" was impossible because Tully valley provided no exit for the water. In this direction, the delta terminates in a primary depositional front.
The outlet for the Onondaga Trough Lake at the time of the 620' delta is uncertain. Grasso (1970) assigned it to an intermediate level in the incision of Rock Cut channel (initial threshold =700'; later lowered to 550'). Though I accept Rock Cut as the probable exit route, there seems no reason for a persistent "hang-up" near 600'. Indeed, the floor of Rock Cut seems to have been lowered suddenly from 700' to 550' (Hand and Muller, 1972). In light of this, I would suggest that Rock Cut and High Bridge channels were clear and over-deepened when the 620' deltas formed, and that tailwater control was established farther east by the 580' floor of Pools Brook channel or by the prevailing level of Lake Iroquois into which Pools Brook channel emptied.

View of Northern part of Onondaga Valley
Gravel operation on far side of valley is in the lowest (520') terrace. Escape of water at this time must have been directly controlled by the level of Lake Iroquois, possibly by way of Erie channel (410').

Inlet of Smoky Hollow
Crossing western (inlet) end of Smoky Hollow. This is the southernmost of the "Syracuse" channels cut into the upland between Onondaga valley and Butternut valley. Smoky Hollow is excavated in Marcellus Shale. Incision began at 900'. The channel floor was at 790' at time of abandonment. Hence, while Smoky Hollow was its outlet, the lake in Onondaga valley at this point varied in depth from about 480' to 370'.

STOP 5 Clark Reservation State Park
The abandoned waterfall at the head of Clark Reservation channel illustrates an efficient and characteristic mode of cutting through the Onondaga Limestone: by headward migration of a waterfall. (Channels in the Marcellus Shale more likely were created by vertical downcutting, i.e., incision.) The bedrock threshold here (770') probably controlled lake level in Cedarvale trough while the delta at Stop 4 (Saunders' gravel pit) was forming.
Though not as high as Niagara (120' vs. 160'), Clark Reservation falls is virtually identical to Horseshoe Falls of the Niagara in terms of both planform and size.
At this Stop we will consider the activation sequence of the "Syracuse" channels. All have dimensions requiring "Great Lakes" (Lake Warren) drainage. All were active in late Wisconsinan time. Most (all?) have had complex histories, involving more than one period of excavation.
Restricted (channelized) flow across the Onondaga/Butternut spur began with Smoky Hollow. Scour began at the 900' level, and the channel was abandoned when its floor (at the west-end entry) had been lowered to 790'. Reworked drift in delta deposits in Butternut valley shows that final excavation involved removal of fill from a channel predating the last glacial override. Origin of the cut-off "meander" loop is not well understood, but relict drift deposits in this loop are further evidence of complex history. The scour and delta surfaces between 800' and 900' in Cedarvale trough probably relate to a gradually falling lake controlled by the Smoky Hollow outlet.
Ice retreat soon opened a more northerly escape route through Clark Reservation, establishing an Onondaga-valley lake level controlled by the bedrock threshold above the falls (770'). Cedarvale deltas tied to this threshold include the one seen at Stop 4. Drainage evidently followed the retreating ice margin northward, scouring to bedrock, until Nottingham Road channel became active. The sill leading to the abandoned waterfall at the head of Nottingham channel stands at 700'.
Intermediate points of stabilization were the two abandoned waterfalls in the south wall of Rock Cut (760', 730'). These falls show that the eastern half of Rock Cut was open at this time. However, as discussed by Hand and Muller (1972), subsequent activation of Nottingham channel would not have been possible unless the western half of Rock Cut remained plugged, and a (drift? ice ?) barrier separated the approach to Nottingham from the two Rock Cut plunge basins. Catastrophic failure of this narrow barrier was invoked by Hand and Muller to clear Rock Cut and High Bridge channels to their present levels, creating prominent deltas at the eastern ends of these channels and abruptly lowering the lake level in Onondaga valley by 100'.
Delta terraces in Cedarvale trough seem compatible with this scenario. They suggest that after a period of gradual decline from about 790' to 700' (corresponding to gradual lowering of bedrock thresholds between Clark Reservation and Nottingham), there was an abrupt drop to 660' - 600'. None of the "Syracuse" channels could have provided suitable control for this latter (very extensive) set of deltas. However, if Rock Cut and High Bridge channels were cleared as proposed by Hand and Muller, they would have provided an over-deepened (slow-flowing) exit route to a level-control point still farther east, namely Pools Brook channel (590') or young Lake Iroquois beyond.
Other questions surround Meadowbrook channel, whose floor elevation (western end) is 550', essentially matching that of Rock Cut. Original cutting of Meadowbrook undoubtedly occurred a long time ago, but its graded floor and mild truncation of drumlins indicate that it carried at least some flow during final deglaciation. How could flow have been forced through Meadowbrook if Rock Cut had already been opened to the same level? (Indeed, a somewhat lower level, since evidently some material has been removed from the floor of Meadowbrook channel.) Hand (1978) invoked an otherwise undocumented oscillation of the ice front to permit clearing Meadowbrook prior to opening the western half of Rock Cut. Subsequent blockage of Meadowbrook by ice was then called upon to reactivate Nottingham Road channel and set the stage for catastrophic flushing of the western part of Rock Cut. A simpler and perhaps better alternative envisions a "base" discharge adequate to have some erosive capability even when divided between two major channels. (Channels east of Limestone valley would have been abandoned by this time, and flow from Rock Cut and Meadowbrook would have escaped directly out the northern end of Butternut valley.)

STOP 6 near Onondaga Resource Recovery Facility
Observe Rock Cut channel: 100-150' deep, 1000' wide (floor), 2 mi long, threshold elevation 550'. Entrance ramp and the Onondaga Resource Recovery facility are directly below where Great Lakes discharge must have flowed in its approach to Nottingham channel. At that time, this (western) part of Rock Cut must have remained full of drift or ice. The postulated barrier that prevented Nottingham discharge from diverting to the (cleared) eastern end of Rock Cut was located just beyond (east of) the Resource Recovery facility. Next come the two abandoned waterfalls spilling over the south wall. These provided the flow that cleared out Rock Cut from here on east, prior to activation of Nottingham channel. A trailer park occupies one plunge basin; the other (upstream) became partial filled by a boulder bar when the barrier failed, and is not easily seen from the highway.
Gravel quarrying operations at the east end of Rock Cut have removed much of the delta attributed to the brief episode of catastrophic discharge attending barrier failure.

Climbing up Delta
You are climbing onto a remnant of the delta deposits dumped into Butternut valley during catastrophic flow from Rock Cut. Butternut Creek subsequently isolated this delta remnant and created the steep slope.
On the right side of the road, property of Dewitt Sportsmen's Club, preserves original configuration of the top of the deposit. Note the adverse slope of the broad distributary-like scour. To contruct this "delta" (expansion bar?), flow in Rock Cut must have exceeded 65 feet!

STOP 7 - Top of delta with huge boulders
This is the top of the delta/expansion bar attributed to the Rock Cut flood. In the early 1970's, a large highway cut (now vegetated and uninstructive) exposed the full thickness (50' or more) of the NE-dipping foresets within this delta/bar.
The main point of driving throught this development is to admire the 6-foot boulders used as lawn decorations. These particular boulders (chiefly Onondaga Limestone) were swept out of Rock Cut and stranded here on the top of the delta. Most, however, were swept to the lip of the delta, from where they rolled down the delta front to form a layer of 2-6' boulders several feet thick beneath the main foresets. The size of these boulders and the need to push them up the backside of this "delta' helped convince Hand and Muller of the reality of the Rock Cut dam burst.

End

B4: PATTERNS OF PHYLETIC EVOLUTION IN THE TRENTON GROUP
ROBERT TITUS
Hartwick College
Oneonta, New York 13820
The Trenton Group has been the subject of 60 years of continuous biostratigraphic study since Marshall Kay began his work during the early 1930's. The unit displays a remarkably rich and diverse fossil assemblage which, along with its facies patterns, is now quite well known. The Trenton Group is thus very well suited for research directed at understanding patterns of evolution. This ongoing research program is currently focused on recognizing patterns of intraspecific clinal variation and relating these to facies change in order to develop comprehensive records of evolutionary events. Two case studies are now complete. Evolution within the crinoid genus Ectenocrinus has been described (Titus, 1989). A similar paper on the brachiopod genus Sowerbyella is pending (Titus, 1992). This field guide will serve as an appendix to both of those papers.

B4: PATTERNS OF PHYLETIC EVOLUTION IN THE TRENTON GROUP

STOP 1. The Napanee Limestone
The strata here are primarily thick bedded, black micrites which have been interpreted as a nearshore lagoon facies. Sowerbyella is abundant. This form has traditionally been identified as s. punctostriatus. It is herein reinterpreted as the quiet water, mud bottom clinal variant of s. curdsvillensis. Examine the brachial interiors and see the preponderence of simple forms. Medial septa can be seen but muscle scars, vascular markings and subperipheral thickenings are uncommon. The pedicle exterior usually displays alate corners and a well developed medial fold giving this valve a peaked appearance.

STOP 2. The Kings Falls Limestone
The lower strata here are primarily thick bedded, coarse grained biosparites which have been interpreted as a barrier shoal facies, lying offshore of the Napanee lagoon facies. Toward the top of the outcrop the facies grades into a shallow shelf facies. While, at this location, these strata overlie those of the lagoon facies, presumably there were contemporaneous lagoonal facies elsewhere. Sowerbyella is very abundant at the base of this outcrop. This form is larger than the one in the lagoon facies. Most of the brachial interiors are quite ornate. They have medial septa, muscle scars, vascular markings and subperipheral thickenings. The pedicle exteriors have blunt corners. They don't often show medial folds. Instead they tend to be flattened or broadly rounded. This form has traditionally been identified as S.curdsvillensis. It is herein reinterpreted as the agitated facies clinal variant of a more broadly defined S. curdsvillensis. By collecting enough brachial interiors at these two outcrops, an assemblage of forms can soon be put together that show the gradation between the lagoon and the shoal clinal variants.

STOP 3. The Sugar River Limestone
Climb down to creek and walk to exposure east of and about 50 m below the bridge.
There is a prominent re-entrant below the bridge which can be traced downstream. This is a thick bentonite which lies 10 m (32 ft.) below the top of the Sugar River Limestone. Sowerbyella is rare in the deeper water facies above this bentonite, but common in the shallower facies below. Examine the strata several meters below the bentonite. The common form of Sowerbyella here is the mud bottom, quiet water form. Although some of the brachial interiors are ornate, most are plain. Medial septa are seen but other features are uncommon. The form is relatively small. Pedicle exteriors often display a medial fold and alate corners. This location records a return of both quiet water conditions and the quiet water clinal variant of Sowerbyella. Upstream into the highest strata of the Sugar River Limestone, and for a considerable distance into the overlying Denley Limestone, Sowerbyella is quite scarce. This zone is part of the first Sowerbyella bottleneck.
The next location is designed to display an example of model 3 clinal variation. The middle Trentonian crinoid genus Ectenocrinus occupied a shallow to deep shelf range of environments. Because of bank margin steepening, the deep end of its range was deteriorating while shallowing facies offered opportunities for Ectenocrinus in shallow water environments. The result is a kind of clinal orthoselection.

STOP 4. The Sugar River And Denley Limestones
Park and follow one of the trails down to Roaring Brook and then climb down to the top of Whitikers Falls.
At the base of the falls a re-entrant can be seen. This is the same bentonite which was observed at Mill Creek in Lowville. Here it is also 10 m (32ft.) below the top of the Sugar River Limestone. The bentonite is a marker bed which is found at the same level at all outcrops from Mill Creek, Lowville to Sugar River. It has not been found at Deer River or at any of the Mohawk Valley locations.
Examine the several meters of strata above the falls. Ectenocrinus is represented by moderately abundant columnals. Look carefully as these columnals are small. It is very helpful to bring a water container and pour water on columna! rich beds. This brings out the contrast between the columnals and their micritic groundmass. Ectenocrinus is easily recognized by its trimeric morphology. Each columnal is composed of three elements fused together along faintly visible sutures. The most common form is a triangle with very rounded corners. At first glance the lumina appear to be triangular, and many are. But you will soon notice that many also have very poorly developed 4th and 5th points, along with three long and attenuated points (Fig. 5i-5m). All specimens at this level belong to the species E. triangulus.
Climb to the level above where the trail intersects the stream. Here and for quite a distance upstream Ectenocrinus columnals are different. Now they are generally rounder and the lumina are composed of more equal sized points (Fig. 5s-5v). Forms at this level are intermediate between E. triangulus and its descendent E. simplex. Continue upstream and observe the increasingly abundant columnals of Ectenocrinus. The transition from E. triangulus to E. simplex is not just one of morphology. E. triangulus was a relatively stenotopic form which never became especially abundant. The descendent, E. simplex, was altogether different. It was eurytopic and one of the dominant forms in the upper Trenton Group, a "weed" crinoid. This evolutionary event records an ecological transition from the K-strategist ancestor to the r-strategist descendent.
The last locations are designed to illustrate model 2 examples of clinal variation. Sowerbyella passed through two facies bottlenecks, one at the base of the middle Trentonian and one at the base of the upper Trentonian (Fig. 3, arrows). The best place to study the Sowerbyella of the middle Trentonian is at Mill Creek, Lowville, but as that outcrop extends for such a long distance along the stream, it is not practical to include this location in a one-day trip. We will examine middle Trentonian forms at other locations, stops 5 and 6.

STOP 5. The Denley Limestone
Climb to the exposure immediately above the bridge.
At this level the transition to Ectenocrinus simplex is complete. Virtually all Ectenocrinus columnals, upstream from the bridge, are round with pentagonal lumina (Fig. 5z-5aa). Sowerbyella is not common here but the specimens which can be seen are of interest. They are nearly identical to the quiet water lower Trentonian forms. They have plain brachial interiors; the pedicle exteriors have medial ridges and alate corners.

STOP 6. The Denley Limestone
The exposure here is of the middle Denley Limestone. The facies are the shallow shelf possibly grading into the barrier (Fig. 3). Several types of Sowerbyella can be recognized from the brachial interior structure. Many have plain interiors. While medial septa are present, none of the other internal structures are seen. The other type has an ornate brachial interior. Medial septa, muscle scars and subperipheral thickenings can be seen, some or all, on the same interiors. The plain forms found at this outcrop are typical of the Denley's deeper shelf facies while the ornate forms, although never very common, are typical of the more shallow and agitated facies. Significantly, vascular markings are quite unusual and these ornate forms are never as large as their lower Trentonian equivalents. Pedicle exteriors are more inflated and rounded. This is Sowerbyella n. sp.

STOP 7. The Upper Denley Limestone
Park, descend dirt path to outcrop.
The best location to see Sowerbyella next is at the outcrop of the lower Steuben Limestone on Rt. 177 just west of Rodman, but this is too far away for our trip today. The Rodman exposure shows Sowerbyella within the second bottleneck (Fig. 3, arrow). Specimens there are small and have a well developed, broadly rounded medial fold. At Talcottsville we can see Sowerbyella in the barrier facies just below this second bottleneck. The form is abundant up to the base of the falls and then quite a bit less common in the bottlenecking beds above. The specimens here are, for the most part, characterized by well inflated pedicle exteriors which sometimes display the broadly rounded medial folds typical of the second bottleneck. Brachial interiors are generally plain. Notice the magnificent display of large symmetrical ripple marks (pararipples) here.

STOP 8. The Hillier Limestone
Descend to outcrop east of the brook.
The Hillier Limestone is exposed all along Wells Creek and Big Brook. The environment of deposition was quiet deep shelf and the deposits are mostly biomicrites. This location is above the second facies bottleneck and a third species of Sowerbyella is exposed. The form, S. subovalis, is characterized by a greatly inflated pedicle exterior with a broadly rounded medial fold. Brachial interiors are mostly plain. Medial septa are seen, and sometimes poorly developed subperipheral folds can be found, but muscle scars and vascular markings are absent. These traits are apparently inherited from the clinal variants of S. n. sp. which made it through the second bottleneck. The ones on Big Brook are larger than their middle Trentonian ancestors.

B5: SURFICIAL GEOLOGY AND SOILS OF SOUTHERN MADISON COUNTY, NEW YORK
Bruce W. Selleck
Hamilton, New York
Introduction and General Bedrock Geology:
Southern Madison County, New York lies south of the Onondaga-Helderberg Escarpment on the northern limits of the Appalachian Plateau. Local relief is approximately 600 feet, with valley floor elevations of 1100 feet in the vicinity of Hamilton, New York. The region is underlain by middle Devonian shales, siltstones and sandstones of the Hamilton Group. These fossiliferous rocks are rather poorly resistant to erosion, and surface outcrops are rare except in stream valleys and along steeply-sloping valley walls. One prominent sandstone unit in the Hamilton Group, the Chenango Sandstone, was quarried in the area as dimension stone. The older buildings on the Colgate University campus are built of Chenango Sandstone quarried on the hill south of the main campus.
Progressively older Paleozoic rock units are exposed to the north, including lower and middle Devonian limestones of the Onondaga and Helderberg Groups, the lower Devonian Oriskany Sandstone, shales, sandstones and dolostones of Silurian age, upper Ordovician shales, and lower and middle Ordovician limestones. Upper Cambrian sandstones and dolostone overly Proterozoic basement rocks in the Mohawk Valley. Lithologies representing all of these rock units can be found within the glacial drift which mantles the bedrock of southern Madison County. The dominant exotic (lithologies other than Hamilton Group) rock types in the drift are limestone, dolostone, chert, sandstone and various Proterozoic rocks of Adirondack origin.

B5: SURFICIAL GEOLOGY AND SOILS OF SOUTHERN MADISON COUNTY, NEW YORK

STOP 1. Madison Street Quarry
This quarry is on private property.
The exposure is at the margin of a kame terrace that continues north along the valley the holds Lake Moraine. Depending on the conditions at the working face, large-scale cross-stratification can be seen, suggesting that this portion of the terrace formed as a lake delta, indicating that ponded water was present to the south. Exposures also contain highly chaotic, poorly sorted debris flow deposits.
Note the composition of the clast suite, rounding of larger clasts, and heterogeneous textures and fabrics.

STOP 2. Valley Overlook on Airport Road
We stop briefly here for a view to the south of the major geomorphic features of the Hamilton area. Note the obvious terraces that flank the lower valley walls, possible glacial trim lines on middle and upper valley walls, and the subdued topography of the valley floor. Note also the feeder canal in the near foreground.

Cross feeder canal from Lake Moraine

Note prominent terrace on left.

STOP 3. Woodman Pond and Chenango Canal
Woodman Pond is a kettle lake that was once used as the water supply of the Village of Hamilton. The village now gains water from wells within the village that are located in highly permeable outwash gravels. This supply, available as a backup, was prone to high algal/organic loads because of overwintering flocks of 1000+ Canada Geese. Note the steep, angle of repose slopes that rim portions of the pond and adjacent marshlands.
Immediately to the west is the Chenango Canal. The canal system in this area was originally developed in the late 1830's for transport of goods from Binghamton to Utica. In the Hamilton area, a system of feeder canals captured south-flowing drainage of the Chenango River, Payne Creek and Kingsley Brook and diverted that water to the north. The Chenango Canal was essentially abandoned as a transportation system in the middle part of the 19th century as railroads were constructed. Portions of the canal system are still used, however, to supply water to the New York State Barge Canal system. The old Chenango Canal at this site carries water from Payne Creek (Lake Moraine) and the Chenango River to Oriskany Creek, which supplies the Barge Canal.

Howard Series soils on left.

Cossing feeder canal from Chenango River.

Crossing feeder canal from Chenango River.

STOP 4. Randallsville Road Terraces
Two obvious terrace levels are present in this area. Both are underlain by relatively well-sorted gravelly sand, and the material is clearly of fluvial-glacial origin. It has been proposed that the terraces represent either glacial lake deltas or kame terraces, although these may also be erosional terraces formed during late Phase 3 deglaciation.
The soils on the terraces are excellent representatives of the Palmyra series, and are very good agricultural soils. The feeder canal at this site carries water from the Chenango River to the north, skirting the Village of Hamilton, emptying into the Chenango Canal immediately north of the village.

Crossing feeder canal and Chenango River.

Stone house at intersection is made of Chenango Sandstone.

STOP 5. Bewkes Center
The Bewkes Center property was a gift to Colgate from a former chair of the Board of Trustees, E. Garrett Bewkes. We will proceed to the wooded area in the vicinity of Seymour Pond to examine soil profiles in Stockbridge and Volusia series soils, and compare soil profile development in areas of deciduous and coniferous forest canopies.
Seymour Pond may be of kettle origin. However, the surrounding surficial material is ablation till. A more likely origin is the interruption of surface drainage by the configuration of ablation till deposits at the northeastern margin of the lake. The recent sediments in the lake are almost entirely of biogenic origin (diatom and algal/organic). The lake waters are well-buffered, with a pH that varies from 6.8-6.9.

STOP 6. Craine Lake
Craine Lake is an obvious kettle lake surrounded by steep, angle of repose slopes in outwash. The soils developed on the outwash surface are Palmyra series. Craine Lake waters are well-buffered, and precipitation of fine-grained calcium carbonate occurs on aquatic plants during the warm summer months.

Cossitt Concrete Sand and Gravel Plant on left.
The quarrying is developed in outwash.

STOP 7. Horton Road (time permitting)
The fields and pastures of the uplands along Horton Road are underlain by a thin veneer of lodgement till with a high percentage of local Hamilton Group lithologies characterizing the clast suite.. Typical Mardin Series soils are developed on the till. These soils are moderately good agricultural soils, but are slow to drain in spring. As we continue east on Horton Road, and onto Preston Hill Road, you will note a number of marshy areas which attest to the rather poor drainage typical of Mardin series soils.