Goat Island Formation of Lockport Group in report area is subdivided into (ascending) Niagara Falls, Ancaster, and Vinemount Members. Ancaster and Vinemount are extended into NY from their type areas in Hamilton, Ontario. The Niagara Falls Member overlies the Pekin Member of the Gasport Limestone. The upper 1.5 m of the Niagara Falls is a distinctive interval of very dark gray, vuggy dolostone with distinct, white weathering stromatoporoids and corals. Total thickness and description not given. Goat Island and its members are Middle Silurian.

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

Lockport Group 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 Niagara Falls Member of the Goat Island Dolomite for Niagara Falls, Niagara Co., western NY. Consists of light-olive to brownish-gray, sucrosic, medium-grained, thick-bedded to massive, commonly porous and vuggy dolomite that weathers very light gray. From type locality eastward to Brockport, Monroe Co., NY, member is typically biostromal and characterized by abundant stromatoporoids. East of the Niagara River Gorge, two distinct units are recognized. Unit A is a pale pinkish-gray to olive-gray, crinoidal, dolopackstone and grainstone, and a thin- to thick-bedded, pale olive-gray, fine-grained dolowackestone that is extremely vuggy. Unit B is a dark-gray to pale pinkish-gray massive dolorudite that contains stromatoporoids and favositids. Thickness of the Niagara Falls is 3 ft at Niagara River Gorge to more than 15 ft at Lockport, NY. Unconformably overlies the Pekin Member of the Gasport Dolomite and conformably underlies the Ancaster Member of the Goat Island Dolomite. West of Hamilton, Ontario, CAN, the Niagara Fall Member grades laterally into the massive carbonates of the Amabel Formation; to the east it grades laterally into the sandy dolomites of the Penfield Formation. The Niagara Falls is of Early and Late Silurian (latest Wenlockian and earliest Ludlovian) age based on conodonts. [Silurian time scale of Hartland and others (1982) used in this report.]

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