We are attempting to characterize the nature of linear topographic features in the vicinity of French Creek, northwestern Pennsylvania. Straight valleys that trend north to northwest and that are partially filled with glaciofluvial deposits distinguish prominent lineaments in Crawford, Venango, and Mercer Counties. The traces of these linear valleys are 1-15 mi (1.6-24 km) long and 10-4,000 ft (3-1,220 m) wide. The vertical extents of the lineaments are assumed to be proportional to their lengths. We assume that the topographic lineaments mark easily eroded zones coincident with fractures.
The French Creek lineaments have been plotted on a Landsat photo, glacial map, regional map, and topographic maps. Subsurface structural and isopach maps may show facies changes or anomalous thickness across the lineaments. Geochemical surveys determine if there is any enhanced vertical migration of hydrocarbons along a lineament, and very low-frequency magnetic surveys would indicate any increase in groundwater concentration associated with the fracture zones. Well log data on initial production and breakdown pressures have been compared to lineament positions for possible correlations.