B7: DACRYOCONARID BIOEVENTS OF THE ONONDAGA FORMATION AND THE MARCELLUS SUBGROUP, CHERRY VALLEY, NEW YORK
RICHARD H. LINDEMANN
Department of Geosciences
Skidmore College
Saratoga Springs, New York 12866
INTRODUCTION
The Order Dacryoconarida Fisher 1962 is a taxon of extinct and enigmatic conical microfossils that occur in marine strata of the Devonian System. Although the taxonomic status of the group and its phylogenetic affinities are not universally agreed upon, unequivocal dacryoconarids (dacs) range from upper Lochovian strata to the Frasnian-Famennian mass extinction boundary. Regardless of their biologic affinities, the organisms themselves are understood to have been marine animals, which were predominantly planktic in habit and pelagic in habitat. Within the region of the Old Word Realm, the dacs are represented by more than thirty genera and scores of species from which sets of biozones have been developed rivaling those of the conodonts in their detail and temporal resolution (see Lutke, 1979, 1985; Alberti, 1993; Oliver and Chlupac, 1991; Weddige, 1998). Old World dacs are also diagnostic of several Devonian bioevents, most notably for present purposes the lower Eifelian Chotec Event and the upper Eifelian Kacak-otmari Event(s). Such is not the case in the Devonian of eastern North America where the dacs have been afforded little attention, and the stratigraphic ranges of the few known species are themselves incompletely documented. It is the purpose of this field trip to introduce participants to dacryoconarid genera and bioevents as they are currently understood to be recorded in the Onondaga Formation and the Marcellus Subgroup at Cherry Valley, New York (CVNY).

B7: DACRYOCONARID BIOEVENTS OF THE ONONDAGA FORMATION AND THE MARCELLUS SUBGROUP, CHERRY VALLEY, NEW YORK

STOP 1. DACRYOCONARID EVENT I.
Pull on to the right shoulder of the road just beyond a large road sign above the top of the road cut. Walk down hill to the base of the roadcut.
The base of this outcrop is in the upper Carlisle Center, which is characterized by the ichnofossil Zoophycos. The sub-Onondaga disconformity is marked by abundant phosphate nodules at the Edgecliff-Carlisle Center contact. Much of the Onondaga Formation's Edgecliff Member is a massive to thick-bedded, coraliferous limestone. The upper Edgecliff contains nodules of light-gray chert and the top of the member is easily recognized the red staining of oxidized pyrite nodules. The base of the Dacryoconarid Event I interval is coincident with the Edgecliff-Nedrow disconformity, which is at the contact of this pyriteiferous Edgecliff bed and base of the lowermost argillaceous Nedrow bed. The base of the Nedrow is also the base of the Viriatellina and Tentaculites scalariformis local range zones. At this locality, the fauna of Dacryoconarid Event I appears to be restricted to the two argillaceous intervals of the Nedrow. The top of this interval corresponds to the top of the T. scalariformis local range zone, and to the uppermost known occurrence of Viriatellina in the Onondaga Formation.
The arbitrarily chosen Nedrow-Moorehouse contact is the bed of limestone that contains the lowermost occurrence of dark-gray chert nodules. Immediately above this horizon, there are two argillaceous intervals, which may be correlative with the two uppermost Nedrow "black beds" of central New York. If this correlation proves to be correct, strata referred to the lower Moorehouse at this locality are correlative with the upper Nedrow of central New York and with the Chotec Event. In any case, the base of the Dacryoconarid Event I interval is either at, or in proximity to, the base of the Eifelian Stage.

Cherry Valley and Berne Member of Oatka Creek Fm.
Drive uphill a short distance and park in the highway department staging area. The Cherry Valley Member and the lower beds of the Berne Member of the Oatka Creek Formation are exposed in the road cut immediately above the staging area. As it is more convenient to examine and collect from this interval here than it is at Stop 3, we will do so.

Talus blocks of the Carlisle Center
Drive in the right hand lane and decelerate immediately after passing beneath the old railroad overpass. If the fates have been kind, there will be large talus blocks of the of the Carlisle Center, which may afford excellent bedding plane exposures of Zoophycos. If this is the case, we will stop briefly for photographs. Please do not damage, or collect from, these large blocks. There are plenty of small blocks to be had that do not require the use of a hammer.

STOP 2. DACRYOCONARID EVENT II
The 2 m exposure of massive grainstone and packstone on the south side of Rt 20 is the easternmost exposure of the Seneca Limestone. The Tioga B Bentonite occurs in the reentrant at the base of the exposure. The low exposure of packstone on the north side of Rt. 20 is in the uppermost Moorehouse. At this locality, both members were deposited toward the culmination of a regressive phase, the beginning of which is recorded in the Moorehouse at Stop I. The top of the Seneca is an erosional truncation surface. At other localities in central and eastern New York, this surface is a classic Devonian bone bed.
The base of the Bakoven Shale is not exposed here, though it has been excavated in a stream gully within sight of this outcrop and is (sometimes) exposed nearby at Optional Stop A. The Bakoven was deposited during a eustatic flooding phase which appears to have breached the transcontinental arch, permitting the immigration of dacs from the equatorial Old World Realm, of what is now Arctic Canada, into the Eastern Americas Realm. Striatostyliolina was the first new dac to access the northern Appalachian Basin during this highstand. Its first occurrence is coincident with the base of the Bakoven Shale and is the diagnostic of Dacryoconarid Event II.

STOP 3. DACRYOCONARID EVENTS III AND IV.
The base of the Chestnut Street road cut is in the upper concretionary part of the Bakoven Shale. The upper part of the outcrop, which is visible from the road, is in the Berne Member of Oatka Creek Formation. The massive limestone bed between them is the Cherry Valley (Fig. 1). The Cherry Valley immediately overlies a centimeter-scale bed of shale, which overlies a 10-25 cm bed of limestone. These are the Lincoln Park and Chestnut Street submembers of the Union Springs' Hurley Member. Dacryoconarid Event III, which is not regarded to be correlative with the Lower Kacak Event of Walliser (1995), occupies the concretionary interval of the Bakoven and the Chestnut Street bed. This is the total known range zone of Costulatostyliolina (Fig. 1) in the northern Appalachian Basin. Similarly, Nowakia also first occurs in the Bakoven and is present in the Chestnut Street bed. Nowakia is absent from the section above this bed until it reappears in the Berne Member of the Oatka Creek Formation 23-34 m above the top of the Cherry Valley. This 11 m thick section of the Berne is interval of Dacryoconarid Event IV. It is now regarded to be correlative with the Upper Kacak Event of Walliser (1995). This part of the section can be accessed either by scrambling up through the very sooty lower Berne above the Cherry Valley or by following a path up hill beneath the power line that intersects the road just above where we turned off of Rt. 20. Intermittent outcrops are present along the south side to this path and the hill side immediately above it. The crest of the section along the powerline is in a fine-grained arenite that lies above the highest occurrence of Nowakia, which marks the top of the Dacryoconarid Event IV interval.

Stop A. The upper Onondaga Fm and lower Bakoven Shale
The upper Onondaga Formation and lower Bakoven Shale are exposed in a ditch/ephemeral stream on the west side of the road. If the weather has been dry, it is possible to walk up through the uppermost limestone beds and locate the Onondaga-Bakoven contact. The lowermost shale bed is Daryoconarid Event I, the first occurrence of iStriatostyliolina. Watch your trip leader carefully for the optimal place to pull on to the right shoulder of the road and park.

Stop B. Union Springs Formation
This stop is a road cut in the Union Springs Formation on Camp Pinnacle Road south of John Boyd Thatcher State Park and above the Helderberg escarpment. The top of the Onondaga Formation is exposed on the flats below the intersection of Beaverdam and Camp Pinnacle Roads. The Cherry Valley Limestone is present in the ditch uphill from the shale exposure. Only Styliolina and Viriatellina are present in the upper section of the Union Springs at this location. Although Costulatostylioina is not present, Nowakia is abundant in the lower, darker part of the section. The form of Nowakia that occurs in this interval is very similar to N. otomari, though it does not appear to be that species. Nonetheless, this part of the outcrop is referred to the Dacryoconarid Event III interval and is regarded to be correlative with the Lower Kacak Event of Walliser (1995).