Revised Pennsylvanian Lithostratigraphy Of The Broad Top Coalfield, South-Central Pennsylvania

The present investigation relied heavily on numerous records of deep diamond-drill holes and underground mine maps from various sources and reinterpretation of the PAGS Broad Top reference core hole drilled in 1984, which provided the first evidence of Glenshaw Formation (lower Conemaugh Group) marine zones in the coalfield—supplying a key to regional correlations. Based on analysis of local and regional datasets, identified Glenshaw marine zones in Broad Top include (all the following series of units in ascending stratigraphic order) the Woods Run, Noble, and Ames. Principal Broad Top units and their Main Bituminous field counterparts (in parentheses) representing key beds defining formational contacts are the Wood (Brookville) coal, Speer (Upper Freeport) coal, and Ames marine zone. In addition to the Wood and Speer, other important mineable coals include the Fulton (Lower Kittanning), Barnett (Middle Kittanning), Twin (Middle Kittanning rider), Barnettstown no. 1 (Upper Kittanning), Kelly (Lower Freeport), and Rogers (Harlem). Thus, the newly recognized or redefined mappable bedrock geologic units in Broad Top consist of the Pottsville, Allegheny, Glenshaw, and Casselman Formations and range in age from Early to Late Pennsylvanian (middle Morrowan to late Missourian), or from approximately 321 to 304 Ma, spanning about
17 Myr.