Pg. 2 (fig. 1), 34-35, 36 (fig. 11), 55-57, 65-67, pl. 1. Minisink Limestone included in Helderberg Group in New Jersey and Pennsylvania. Age is Early Devonian.
Source: Changes in stratigraphic nomenclature, 1967 (USGS Bull. 1274-A, p. A9).
Newly named Bald Hill Bentonite Beds (A,B,C) have been identified within Helderberg strata in PA, NY, MD, WV, and VA. Beds A and B occur within the New Scotland Formation in PA and WV and within the correlative Corriganville Limestone in MD. Bed C occurs near the base of the overlying Mandata in all three states. In NY, Beds A, B, and C occur within the middle member of the Kalkberg Limestone. Bed A is presumably equivalent to Rickard's (1962) Kalkberg bentonite.
Source: GNU records (USGS DDS-6; Reston GNULEX).
Helderberg Limestone accepted for use in subsurface in vicinity of Sissonville quad, Kanawha, Jackson, and Putnam Cos, WV.
Source: GNU records (USGS DDS-6; Reston GNULEX).
The Helderberg Group in the northern VA, northeastern WV, and western MD is of latest Silurian (Pridolian) and Early Devonian (Lochkovian) age based on conodont biostratigraphy. The Silurian-Devonian boundary occurs in the upper part of the Keyser Limestone. The Helderberg Group in this area consists of (ascending) the Keyser, New Creek, and Licking Creek Limestones.
Source: GNU records (USGS DDS-6; Reston GNULEX).
Helderberg Group in the Catawba syncline is composed of 1 m of Clifton Forge Sandstone Member(?) of Keyser Formation and 8 m of Rocky Gap Sandstone consisting of calcitic, cross-bedded, shoaling marine sandstones containing some poorly preserved marine body fossils. Unconformably overlies the Silurian "Keefer" Sandstone (used informally here.) Age is Early Devonian only in this area.
Source: GNU records (USGS DDS-6; Reston GNULEX).
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