A4: RE-EXAMINATION OF THE TYPE ITHACA FORMATION: CORRELATIONS WITH SECTIONS IN WESTERN NEW YORK
James J. Zambito IV
University of Cincinnati
Department of Geology
500 Geology/Physics Building
Cincinnati, OH, 45221-0013
e-mail: zambitjj@uc.edu
Gordon C. Baird
SUNY College at Fredonia
Department of Geosciences
Fredonia, NY 14063
Carlton E. Brett
Alex J. Bartholomew
SUNY New Paltz
1 Hawk Dr, Wooster Science Bldg
New Paltz, NY 12561
INTRODUCTION
Stratigraphic correlation of the early Frasnian (Genesee Group) in New York has been ongoing for over 150 years (see Kirchgasser 1985 and Kirchgasser et al. 1994 for summary). While recent work has recognized key temporal horizons (e.g., sequence boundaries, condensed sections, and flooding surfaces) in western New York sections, correlation of such horizons into the vicinity of Ithaca, New York is currently ongoing (Kirchgasser 2000, Baird et al. 2006). This study focuses on detailed re-examination of the Ithaca Formation of east-central New York in its type area, which has not been studied in any detail since the early 1980's (see Kirchgasser 1985). We use sequence stratigraphic approach to describe and correlate these strata; a model which was previously unavailable to past researchers. Herein we summarize progress in characterizing small scale sedimentary cycles within the Ithaca Formation, as well as the identification of horizons and/or beds that may be correlative with those previously recognized in western New York sections. We present a working hypothesis of high-resolution correlation within the Ithaca Formation. These include fossil-rich calcareous siltstone and shell-rich limestone beds that appear to record sediment starved intervals associated with both small- and large-scale transgressions. The latter may at least correlate with condensed, styliolinid-rich pelagic limestones in western New York.
Given that certain Genesee divisional units recognized in western New York (Schumacher Bed of the Penn Yan Formation, Genundewa Formation, "Huddle Bed" of conodonts and Styliolina in the basal West River Formation) have not yet been correlated with any certainty into the Ithaca region, and, given that certain Ithaca area units (Renwick Formation, Beebe Limestone, Williams Brook Limestone, as well as some newly described condensed intervals in the lower Ithaca Formation) have not been confidently linked into the stable stratigraphic succession of the Genesee Valley-Erie County region, the results presented here are a "work in progress". By establishing a "cat's cradle" of bed-to-bed matches between the various, large Ithaca gorge sections, we will be able to construct a hierarchy of units and beds that reflect eustatic changes and important bioevents. This linkage of local sections will also allow us to out-correlate marker beds both to the Genesee Valley area and to the east.

A4: RE-EXAMINATION OF THE TYPE ITHACA FORMATION: CORRELATIONS WITH SECTIONS IN WESTERN NEW YORK

Overgrown, but fossiliferous outcrop
0.25 mile long overgrown, but fossiliferous outcrop. The presence of O. mesastrialis and ‘Pugnoides’ places this within the Triphammer member, possibly the University Quarry submember (see Harrington 1970).

Outcrop of West River equivalent strata
Outcrop of West River equivalent strata at the intersection of Warren Rd.

Strata of the Ithaca Formation.

Strata of the Ithaca Formation
Exit for Cayuga Heights Road. Strata of the Ithaca Formation, this will be STOP 5.

Outcrops of Renwick Formation.

Cross Williams Brook
(STOPS 7A and7B will be upper portion of this creek).

STOP 1A. Taughannock State Park (Tully Limestone)
Both STOPS 1A and B are used as an overview to put the Ithaca Formation in perspective with the underlying Middle Devonian strata. At the first stop, the Tully Limestone is accessible above the Moscow Formation of the Hamilton Group. As summarized in Baird and Brett (2003), the Tully represents both significant sedimentological and faunal changes in the Appalachian Basin. Sedimentologically, upper Tully divisions, commencing with the coral-rich Bellona Bed comprise a TST-succession that represents the onset of 101 the Taghanic onlap, a eustatic sea-level rise that locally within the Appalachian Basin resulted in the deposition of the black Geneseo Shale Formation and its correlatives (Harrell, Burkett, etc, see Baird and Brett 2003). Faunally, this onlap is significant because it is concurrent with late stages of the global Taghanic Bioevent, resulting in the suspected demise of Middle Devonian faunas worldwide. As will be demonstrated later in this trip, the demise of the Middle Devonian ‘Hamilton-fauna’ in the Appalachian Basin may not have taken place at this boundary; ‘Hamilton’-characteristic fossils can be found throughout the Frasnian of New York (see Williams 1913 and references therein).

STOP 1B. Taughannock Falls Overview (Lower Genesee Group)
The overlook at Taughannock Falls provides a stunning view of the lower Genesee Group; including the Geneseo Formation, Sherburne Formation, and the lowest Ithaca Formation (Figure 6). Within the walls of this hanging valley both the Fir Tree and Lodi Limestone Beds can be observed. These beds, or associated discontinuities, can be traced throughout most of New York (Baird et al. 1988). Also visible within the gorge wall are the siltstone lenses characteristic of the ‘Renwick facies’, which will be observed in detail at later stops. This is purportedly the highest waterfall east of the Mississippi River.

The Paleontological Research Institution.

Pass outcrops of Renwick Formation.

STOP 2. Ithaca Falls Park, Fall Creek (Warrenella Zone Submember)
This stop allows access to the Renwick Formation (Figs. 1 and 2). This section begins in the Warrenella Zone, near the base of the Renwick Formation. Above this and in the face of Ithaca Falls are the siltstone channel lenses characteristic of the ‘Renwick facies’. Excellent collecting of the Warrenella Zone fauna is possible at this locality. The upper Renwick Formation is inaccessible at this locality, but can be accessed at the nearby gully running up through the old Ithaca Gun Factory, also known as Gun Hill. Due to reportedly high lead levels from test firing of rifles, this small gully and the Ithaca Gun Factory itself are currently posted.

STOP 3. Cascadilla Creek ('Renwick Facies')
This stop begins stratigraphically above the Warrenella Zone, within the siltstone lenses of the 'Renwick facies' (Figures 1 and 2). This is the “Lingula Shales” interval of H.S. Williams (1906). This outcrop offers collecting of the Lingula fauna, including Plumalina plumaria and articulated crinoids (Eutaxocrinus ithacensis).

OPTIONAL STOP. NY-13 (Renwick Formation)
This optional stop shows a continuous section of the intervals seen at STOPS 2 and 3. The base of the section is in the Warrenella Zone (Figures 1 and 2). Above this, the siltstone channel interval ('Renwick facies') is accessible for collection of the Lingula fauna as well as Plumalaria plumalina. Although this outcrop does not reach the Ithaca Falls limestone, the upper portion of this cut is interesting in that it affords the opportunity for close examination of large ball and pillow structures. This is approximately the arbitrary lithological boundary given to the Renwick and overlying Ithaca in the past literature.

Exit at Cayuga Heights.
The well-exposed outcrop along the cloverleaf of strata above the Renwick Formation will be examined later as part of STOP 5.

STOP 4. Twin Glens (Ithaca Falls Limestone Submember)
Park on side of NY-34 near (but 10 feet from) orange hydrant. Proceed on foot to trail along Twin Glens. This is private property, and permission must be granted for access.
The focus of this stop is the Ithaca Falls limestone submember as well as the recurrent 'Hamilton fauna' in the surrounding shales (Figures 1 and 2). At this locality the Ithaca Falls limestone is well developed, showing a sharp erosional base, erosionally lateral-truncation of turbidites, and an angularly truncated upper surface. This bed is excellent for collecting calcite replaced Paleoneilo sp. and Nuculiid bivalves. Above this limestone is a thin bed of crinoid debris that has yielded articulated cladid crinoids (at Fall Creek). Surrounding this bed is a dysaerobic fauna with some characteristic fossils of the 'Hamilton fauna'. This includes Paleoneilo sp., Nuculiid bivalves, ?Mucrospirifer mucronatas (?'Spirifer' posterus, ?Tylothyris mesacostales), Glyptotomaria capillaria, and abundant pelmatozoan material.

Cross upper end of Twin Glens.

STOP 5. NY-13 (Upper Cascadilla Through Cayuga Heights Members)
Excellent exposures are seen at the cloverleaf cut for the NY-13 interchange at Cayuga Heights Road. The lowest part of this exposure begins above the Ithaca Falls limestone. This section is continuously exposed upward to the “Pyramid Mall bed”, therefore including the complete cycles represented by the upper Cascadilla, Triphammer, and Cayuga Heights members (Figures 1 and 2). At this section, the lithology of the University Quarry submember more closely resembles the “Firestone Beds” at Fall Creek, than to the Williams Brook Limestone (STOP 7A), and the Beebe Limestone is a calcisiltite rather than a well developed coquina as seen in the Fall Creek Gorge and at Sixmile Creek (see Figure 3). Most impressive at this section is the cross-sections of FSST siltstone channel complexes visible in the wall face. There is noticeably a large amount of covered section, on NY-13 between the optional stop and STOP 5, in fact larger than should be, given the correlations presented in this trip. Faunally, however, our correlations of the NY-13 section with the other sections studied do agree, and we presently interpret this large covered interval as possibly representing some unseen thrust faulting resulting in stratigraphic duplication.

Power Plant waterfalls and the 'type' “Firestone Beds”.
To the right at the end of Highland Ave. is a suspension bridge and access into Fall Creek Gorge at the Cornell University Power Plant waterfalls and the 'type' “Firestone Beds”.

STOP 6. Beebe Lake (Beebe Limestone Submember)
This stop will show the Beebe Limestone in place near Beebe Lake (Figures 1 and 2). The lithology developed here is very dissimilar to the coquinitic limestone blocks seen downstream as isolated float below the Beebe Lake dam (see text and Fig. 3), but this section at least serves as an accessible type locality for this bed, which has been wanting ever since Caster (1933, 1933a) first named it. This stop also highlights local faulting within the Ithaca Formation. A down-dropped (?) fault block is seen just upstream of the Beebe Limestone.

STOP 7A. Williams Brook (Beebe Limestone Submember)
At Williams Brook, the Beebe Limestone is similar to that observed at STOP 6, a fossiliferous calcisiltite, but here more splayed open. The identification of this bed at this level agrees with Williams et al. (1909) in that the University Quarry interval is equivalent to the Williams Brook Limestone; and furthermore shows that both are distinctly older than the Beebe (Figures 1 and 2). Below the Beebe interval at this section, pyrite-coated concretions, similar to those reworked into the Beebe Limestone at Sixmile Creek, can be observed. If time permits, the "Pyramid Mall beds" are accessible just upstream of here. Proceed across street and onto Private Property to access the Williams Brook Limestone; permission must be given by landowner.

STOP 7B. Williams Brook (Williams Brook Limestone)
Proceed across street and onto Private Property to access the Williams Brook Limestone; permission must be given by landowner.
The Williams Brook Limestone (Caster 1933, 1933a) is one of the most impressive deposits to be seen on this trip. The interval of the coquina itself is approximately 3 meters thick, capping a small waterfall. Channelized bedforms, cross-bedding, truncated inter-bedded siltstones, and reworked concretions and rip-up clasts can be seen within the coquina. The local representation of the "Firestone Beds" at this locality, as well as the channelized bedforms observed in cross-section, suggest deposition within a submarine channel (Figures 1, 2, and 3). The beds above the coquina (Marathon Sandstone of Caster (1933, 1933a), 'Spirifer mesastrialis Zone', and the 'mesastrialis sands' of Williams et al. (1909) and Williams (1913)) contain abundant fossils at some horizons, including Gomphoceras tumidum.