Named the Hostler member of the Hatter formation in central and south-central PA for village of Hostler, Centre Co. Unit is uppermost member of formation. Consists of dark, tan-weathering, massive, richly fossiliferous, siliceous and argillaceous limestone in the lower part, and dark, impure, well-bedded, somewhat laminated, sparsely fossiliferous limestone in the upper part. Thickness is 63 feet at type locality. Overlies Grazier member of Hatter formation and underlies Snyder member of Benner limestone. The Hostler is of Middle Ordovician age.

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

Raised the Hostler to the Hostler formation of the Hatter group in PA.

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

The Hatter Formation has been recognized throughout the Valley and Ridge province in central PA, but changes character in the extreme northeast. According to Wagner (1966), it extends in the subsurface to WV. Unit consists of a basal fossiliferous limestone, overlain by fine-grained limestone containing shaly partings, which in turn is overlain by fucoidal, fossiliferous magnesian limestone. The basal Eyer Member is composed of fossiliferous, medium- to thick-bedded calcarenites interbedded with medium-bedded calcilutites and thin, irregular shaly partings. The middle Grazier Member consists of medium-dark-gray, medium- to thick-bedded calcisiltite and calcilutite. Upper Hostler Member is coarser grained than the Grazier, consisting mostly of calcisiltite and thin interbeds of calcarenite. Upper contact with the Snyder Formation is placed at the oolite beds that mark the base of the Snyder. The Hostler Member is 12+/-2 m thick. No basis given for Late Ordovician age assignment of the Hatter. [No mention of Black River Group.]

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