B3: SILURIAN AND DEVONIAN EURYPTERID HORIZONS IN UPSTATE NEW YORK
Samuel J. Ciurca, Jr.
(paleoresearch at yahoo.com)
Rochester, New York
The upper Salina Group consists of a minimum of 70 feet of argillaceous beds (Camillus Formation) that weather rather rapidly. Most beds are mudstones or dolomitic mudstone and shale. The succeeding Bertie Group begins with the deposition of hypersaline „algal‟ mounds and a eurypterid fauna – the Fort Hill Waterlime (see Ciurca, 1973, 1990). Overlying this is the Oatka Shale – dolomitic mudstone with no fossils currently known.
The initiation of Bertie Group sedimentation with a unit of eurypterid-bearing, stromatolitic waterlime set the stage for deposition of overlying units all, in one way or another, deposited during a regime of extensive microbialite sedimentation in the Late Silurian. This, and the numerous eurypterid faunas, typifies the Bertie Group sequence across upstate New York and southwestern Ontario, Canada.
Ciurca (1990 ), in a redefinition of the Bertie Group, added similar lithologic units that occur above the Akron- Cobleskill to the Group (e.g. Moran Corner Waterlime) considering them part of depositional cycles occurring as the result of the shifting of paleoenvironments to and fro during the close of the Late Silurian of the region. We may never know if latest Silurian strata occur in New York as many of the distinguishing zonal fossils may never be found within our sequences. In the meantime, it has been continuously suggested that Eurypterus characterizes the Late Silurian and that Erieopterus characterizes our Early Devonian (at least in the northeast U.S. and Ontario, Canada). The earliest invasion of the Helderbergian transgression may have removed our latest Late Silurian sediments. See Ciurca 1990, Fig. 5, Distribution of Eurypterid-bearing Waterlimes.
Except for the ‘Eurypterus’ pittsfordensis, found at the base of the Salina Group, true Eurypterus are found throughout the Bertie Group and readily distinguish the beds from units such as the Early Devonian Manlius Group or somewhat equivalent beds (Honeoye Falls Dolostone or the Clanbrassil Formation of southwestern Ontario, Canada) – these are replete with the eurypterid, Erieopterus. Figure 1 Algal mounds (microbialites) in the Fort Hill Waterlime at the base of the Oatka Formation downstream from the NY 96 bridge over Flint Creek, Phelps, N.Y. The dam/falls can be seen in the background. The mounds rest on a layer of dolostone bearing abundant evidence of hypersalinity (e.g. salt hoppers).

B3: SILURIAN AND DEVONIAN EURYPTERID HORIZONS IN UPSTATE NEW YORK

STOP 1. Exposures: The Victor and Phelps Members, Fiddlers Green Fm
The type section of the Fiddlers Green Fm. is along Butternut Creek, north of Jamesville, N.Y., where the upper beds form the top of a waterfall. While the rock there is much darker in appearance, the divisions seen here are recognizable there. At the type section there is an upper, very fine-grained dolostone (Phelps Waterlime) with eurypterids and salt hoppers and below, massive beds of the Victor Dolostone
When I first discovered this locality in the 1960s, I called it Con Loc 1 (or Ciurca Locality 56) as we were trying to keep a hoard of collectors from visiting the site in the early years. The site was glacially polished and striated and quite resistant to intrusion, but with weathering and working it slowly over several years, it produced a large number of eurypterid specimens and associated fauna. After a brief interval of several years, when the site was mostly covered with locally-collected drainage ditch material, the site became popular with eurypterid collectors who continued to excavate the rock layers to the state the exposure is today. The research collection I made over the years is available for study at the Peabody Museum of Natural History in New Haven, Connecticut.

Remington Arms Factory on left

Entering Illion Gorge (Steele Creek)
Entering Ordovician Time Zone

Entering Silurian Time Zone

Vernon Red Shale

Syracuse Formation on left (above creek)

McDonald's - rest stop

Erie Canal Museum on right.

STOP 2. Exposures: Late Silurian and Early Devonian Strata (Clockville)
This is an important section, stratigraphically. Rickard (1962) gives a detailed description of the exposed strata. At the base is the uppermost Fiddlers Green Formation (Bertie Group) with eurypterids and salt hoppers. Overlying strata include the Forge Hollow, ‘Cobleskill,’ Chrysler, Thacher and part of the Olney Formations. At least four eurypterid horizons are present in the section. The Silurian/Devonian boundary occurs within the Chrysler Fm. here. At Chittenango Falls, portions of the Chrysler Fm. are rich in horizons of Celestite – a strontium mineral (STOP 3).

STOP 3. Exposures: Late Silurian and Early Devonian Strata (Celestite locality)
For many years, this was a famous mineral collecting locality (mostly Celestite and Calcite). See text for a description of the stratigraphy. Note the massive beds at the base of the cliff – these are the dolomitic facies of the ‘Cobleskill’ Formation. Slightly farther up the road is Chittenango Falls State Park with one of the most beautiful cascading-type waterfalls. Trails take you to the bottom and are well worth seeing. A side canyon just to the north shows what appears to be large ‘algal’ reefs in the Thacher Fm.

STOP 4. Martisco Reef Complex – ‘Cobleskill’ Formation
This is one of the most unusual facies variations of the ‘Cobleskill’ Formation. Sedimentary structures here are interpreted to be part of a highly dolomitized reef complex with silicified fossils, wedging of beds, unusual black chert deposits and succeeding stromatolite beds with breccia and eurypterids. See Ciurca 2005 and
http://eurypterids.net/MartiscoReefComplex.html
for additional comments. Note: Parts of the overlying Chrysler Fm. are well-displayed here.
One other stop is suggested for those interested on this field trip. From this site, take the road back to NY-5 and head west through Auburn and continue to Waterloo, New York. Turn right on NY-96 and head for Phelps where a bridge right in the village goes over Flint Creek (see text). Looking north from the bridge is the Oatka Shale, a rare outcropping. Looking south, below the dam, is lowermost Fiddlers Green Fm. and above the dam is upper Fiddlers Green Fm. including a suggested paleoseismite represented by the Ellicott Creek Breccia. We can collect samples of this for those interested. Many eurypterid specimens have been retrieved from the Phelps Waterlime of this area. Another interesting feature of this locality is the four foot bed of sandstone at the Silurian/Devonian unconformity (just below the Onondaga Limestone).
OHM 2019: Paper company was demolished in 2016.