DETAILED MAPPING AND STRUCTURAL GEOLOGY OF THE SOUTHERN PORTIONS OF THE BARBOURS AND HILLSGROVE 7.5-MINUTE QUADRANGLES, SULLIVAN AND LYCOMING COUNTIES, PENNSYLVANIA

Detailed mapping was conducted in the Barbours and Hillsgrove 7.5-minute quadrangles, Sullivan and Lycoming Counties, Pennsylvania, to address significant structural inconsistencies between the two adjacent quadrangles as shown on existing geologic maps. Local stratigraphy consists of the Devonian Catskill Formation, Mississippian-Devonian Huntley Mountain Formation, Mississippian Burgoon Sandstone and Mauch Chunk Formation, and the Pennsylvanian Pottsville Sandstone. The main objectives of this research were: (1) to construct a detailed geologic map of the area; (2) resolve the structural inconsistencies between the two adjacent quadrangles; (3) measure the stratigraphic thickness of the Burgoon Sandstone; and (4) to determine the lateral extent of the "Patton" red-beds that have been defined as the upper boundary between the Huntley Mountain Formation and the Burgoon Sandstone. Thickness of the Burgoon Sandstone was measured in an exposed section in the Eagles Mere Quadrangle (East of Hillsgrove) to be 50.1 m, which corresponds with depositional contacts and local dips determined during this study. The “Patton” red-beds are completely absent in the field area, and cannot be considered to be laterally extensive as the boundary between the Huntley Mountain Formation and the Burgoon Sandstone. The absence of the upper “Patton” red-beds and the nature of the contact between the Burgoon Sandstone and the underlying Huntley Mountain Formation suggests that the Burgoon disconformably overlies the Huntley Mountain Formation. Field data has clarified the complex structural aspects in the area, and new depositional contacts have been mapped.