Ammonoid horizons in the Upper Devonian Genesee Formation of New York: Legacy of the Genesee, Portage, and Chemung

Abstract

The names Genesee, Portage and Chemung are indelibly linked to the early Upper Devonian stratigraphy of the Catskill delta in western New York. For over a century generations of stratigraphers struggled in the attempt to correlate these groups eastward from the Genesee Valley into sections around the delta-front at Cayuga Lake. Rapid thickening and intertonguing of facies were the chief difficulties, but the misinterpretation of ammonoids also played a major role in obscuring the facies relationships. Manticoceras sinuosum (Hall, 1843), the index fossil of the Portage Group, was mistaken by James Hall and J. M. Clarke and later workers for species of Ponticeras and Koenenites from horizons in the older Genesee Formation east of Canandaigua Lake. Some of these Genesee ammonoid horizons have been traced from the pelagic facies in the basin into the benthic facies of the delta-front. One of these horizons in the Upper Penn Yan and Middle Ithaca Members may record an interval of transgression or standstill in the progradation of the delta. The ammonoid horizons in the GeneseeFormation at Cayuga Lake are stratigraphic markers which should aid in the taxonomic and biostratigraphic revision of the benthic groups and in the refinement of the paleoecological associations in the delta-front facies.In commencing investigations of any kind, where the objects are numerous, lines must be occasionally drawn; they are to the mind, like steps or rounds of a ladder: we have then a place to stand and look around, and to ascertain fully our position. Vanuxem (1842)

REASSESSMENT OF THE DEVONIAN PROBLEMATICUM PROTONYMPHA AS ANOTHER POST-EDIACARAN VENDOBIONT

“…All these localities are in the lower Moscow Formation, Hamilton Group (Rickard & Fisher 1970a), of Middle Givetian age (Sevon & Woodrow 1985). The overlying Tully Limestone has ammonoids of the Pharciceras amplexum Zone (Kirchgasser 1985;Work et al 2007) and conodonts of the Polygnathus varcus Zone (Davis 1975;Sparling 1999). The assemblage of plants found during this work is typical for the Givetian Svalbardia biozone (Banks et al 1985;Edwards et al 2000), better known from the laterally equivalent Manorkill Formation of the Catskill Front (Retallack & Huang 2011).…”

Conodont biostratigraphy of the Java Formation (Upper Devonian) and the Frasnian-Famennian boundary in western New York State

“…The recent use of high resolution conodont stratigraphy and graphical correlation has allowed recognition of global event horizons within the predominantly fine-grained siliciclastic prodeltaic marine facies of the northern Appalachian Basin. Lower and Middle Frasnian marker beds, goniatites, and conodonts have been mapped and correlated (House, 1978;House and Kirchgasser, 1993;Kirchgasser, 1985;Kirchgasser and House, 1981;Kirchgasser et al, 1994;Kralick, 1994;Fig. 1).…”

Reassessment of the Devonian problematicum Protonympha as another post-Ediacaran vendobiont

“…All these localities are in the lower Moscow Formation, Hamilton Group (Rickard & Fisher ), of Middle Givetian age (Sevon & Woodrow ). The overlying Tully Limestone has ammonoids of the Pharciceras amplexum Zone (Kirchgasser ; Work et al . ) and conodonts of the Polygnathus varcus Zone (Davis ; Sparling ).…”