Gasport Limestone, at the base of the Lockport Group, is divided into the lower Gothic Hill Limestone Member and the upper Pekin Member following the usage of Brett and others (in press: NY State Museum Bull). Pekin Member is described at exposure on Old Pekin Road in the village of Pekin, NY. Here it is 4 to 5 m of thin-bedded, bioturbated argillaceous dolostone. Underlies, with a sharp contact, the Niagara Falls Member of the Goat Island Formation. Age of the Gasport and its two members is Middle Silurian.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Lockport in this report is considered Late Silurian following Rickard (1975) as the NY Geological Survey does not recognize Middle Silurian as does the USGS. The revisions to the Lockport nomenclature discussed in this report will be formally proposed by C.E. Brett in a larger study of the Niagaran Series. The Lockport Group is divided into the (ascending) Gasport Limestone, the Goat Island Dolomite, the Eramosa Dolomite, and the Guelph Dolomite. The Gasport includes the Gothic Hill and Pekin Members, and the Goat Island includes the Niagara Falls, Ancaster, and Vinemount Members. [Though three of the authors of this report (Tepper, Kappel, and Yager) are USGS scientists, the nomenclature used here has not been officially accepted for use by the USGS.]

Source: GNU records (USGS DDS-6; Reston GNULEX).

Named the Pekin Member of the Gasport Dolomite for Pekin, Niagara Co., western NY. Unit is upper member of Gasport. Consists of argillaceous, dark-gray or black, fine-grained, thin- to medium-bedded dolomicrite. Three distinct facies are recognized. Facies A consists of medium- to dark-gray, thin- to medium-bedded and slightly nodular, bioturbated dolomudstone to slightly fossiliferous dolowackestone with crinoid ossicles and rugose corals in the west, and argillaceous to arenaceous dolomite in the east. Facies B consists of coral-stromatoporoid framestones within bioherms up to 20 ft high that are pale buff to greenish gray, weather crinkly, and contain abundant corals. Facies C is a dark-gray, coarse, rubbly dolorudite composed of coral and stromatoporoid fragments in a dark micritic matrix. Thickness of the Pekin is 23 to 33 ft. Conformably overlies the Gothic Hill Member of the Gasport and underlies the Niagara Falls Member of the Goat Island Dolomite, at places conformably and at other places unconformably. The Pekin is of Early Silurian (late Wenlockian) age based on conodonts. [Silurian time-scale of Hartland (1982) used in this paper.]

Source: GNU records (USGS DDS-6; Reston GNULEX).