CORRELATION AND REVISION OF UPPER SILURIAN STRATIGRAPHY ACROSS NEW YORK STATE: NEW APPROACHES AND POSSIBILITIES

The uppermost Silurian stratigraphy of New York State remains one of the more poorly understood intervals in the classic ENA Paleozoic succession. Though more than adequately described in terms of individual stratigraphic units, the interval overall remains confusing in relation to the details of stratigraphic nomenclature and correlation over both small and large geographic scales. Much of the confusion and miscorrelation stems from a paucity of exposure, a scarcity of paleontologic data, and relatively rapid facies changes between the scattered outcrops. Recent examination of existing outcrops and reevaluation of historic and modern literature, with a focus upon setting the stratigraphic units into a broader regional framework, has resulted in the opportunity to revise stratigraphic nomenclature and correlations to reflect a better understanding of the relationships between the various units through this interval.

In west-central NY, this interval includes the Lockport Gp. (Illion Fm.), Salina Gp. (Vernon, Syracuse, Camillus fms.), Bertie Gp. (Fiddlers Green, Scjaquada, Williamsville fms.), Brayman Fm., and Rondout, Manlius fms. These units are often dolomitized, poorly exposed, and lap-out against an unconformity upon older Upper Ordovician bedrock below as one heads towards the Helderbergs in the east.

In northwestern NJ and southeastern NY, the stratigraphic sequence for this interval consists of, from bottom to top, the Shawangunk, Bloomsburg, Poxono Island, Bossardville, Decker Ferry, Rondout (Duttonville, Whiteport and Mashipacong mbrs.), and Manlius formations. In the area between Accord and Kingston NY, the stratigraphic sequence consists of, from bottom to top, the Shawangunk, High Falls, Binnewater, Rondout (Wilbur, Rosendale, Glasco, Whiteport mbrs.), and Manlius formations. Between Accord and the NY-NJ line there also exists a poorly-know unit called the Wawarsing Limestone, found only in the subsurface, that sits below the High Falls/Poxono Island formations. Confusing the situation further is the definition of members of the Rondout/Manlius fms. between NJ and NY, as strata traditionally referred to the lowermost Manlius Fm. in NY are included within the uppermost Rondout Fm. in NJ. The Manlius Fm. is the sole unit to persist into west-central NY north and west of Kingston.