The Marcellus Formation - The Swamp Road Roadcut

   The Marcellus Formation is the lowest (oldest) portion of the Hamilton Group.  The type locality for the Marcellus is at Slate Hill, one mile south of Marcellus, Onondaga County, NY.  However, it is exposed at various sites across New York State.  In central New York the Marcellus divides into three members, the Bridgewater, Solsville, and Pecksport (click here for Stratigraphic Column).  A large roadcut on the east side of Swamp Road 4.4 km north of Morrisville, Madison Co., NY, provides access to the upper portion of the Bridgewater Member, and the lower part of the Solsville Member. 

SwampRd01.JPG (68331 bytes)

    The Bridgewater at the base of the section is a fissile dark silty shale with relatively rare fossils.  The Solsville above it grades from a gray calcareous shale at the base to sandy siltstones and fine sandstones at the top of the section.  A thin concretionary zone separates the two members.  The Solsville is known for well preserved bivalves, gastropods, and brachiopods (see references below).  The shells are generally replaced with black calcite, and in many cases preserve microscopic structual features such as growth lines.   These are most easily found weathered from the rock on the talus slope at the base of the section. 

Fossils found at the Swamp Road Roadcut - I have found (or seen) the following species at the Swamp Road locality.

Aulopora serpens Goldfus.  

Atactotoechus fruticosus (Hall) Hederella sp.
Leptotrypella amplectans (Grabau) Taeniopora exigua Nicholson

Lingula sp. Mucrospirifer mucronatus (Conrad)
Spinocyrtia granulosa (Conrad)  

Cornelites fasciculata Goldfuss   Grammysioides alveata Conrad
Gosseletia triquetra (Conrad) Modiomorpha concentrica (Conrad)
Nuculites oblongatus Conrad Nuculoidea deceptriformis Bailey
Paleoneilo constricta (Conrad) Paleoneilo filosa (Conrad)
Paracyclas proavia Hall  

Bembexia sulcomarginata Hall   Paleozygopleura hamiltoniae Hall
Praematuratropis ovatus nov. sp. Ptomatus patulus (Hall) ?

Spyroceras sp.?  

Phacops rana (Green)  

Ancyrocrinus bulbosus Hall Unidentified columnals

1.  Bailey, J.B. (1983) Middle Devonian Bivalvata from the Solsville Member (Marcellus Formation), Central New York State.  Bull. Amer. Mus. Natl. Hist. 174, 193-326.
2.  Rollins, H.B., Eldredge, N., and Spiller, J. (1971) Gastropoda and Monoplacophora of the Solsville Member (Middle Devonian, Marcellus Formation) in the Chenango Valley, New York State.  Bull. Amer. Mus. Natl. Hist. 144, 131-170.
3.  Cameron, B. (1967) Fossilization of an Ancient (Devonian) Soft-Bodied Worm.  Science 155, 1246-1248.


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Page last revised Feb. 4, 2009