Recent drilling on the Bergton-Crab Run anticline, western Rockingham County, Virginia, has partly delimited a small, potential gas field. The field is in the folded Appalachians, 20-25 miles southeast of the Appalachian structural front, where the carbon ratio is in excess of 80.

The rocks of the Bergton district range in age from Upper Ordovician (Martinsburg shale) to Lower Mississippian (Pocono formation). The major pay zone is the Devonian "Oriskany" sandstone, with minor shows from overlying shales. Along the axial part of the Bergton-Crab Run anticline the "Oriskany" was encountered in wells at a depth of approximately 3,000 feet.

The major structural elements of the area are complex folds; no mappable faults were recognized in the area west of the North Mountain fault, which lies about 11 miles southeast of the Bergton-Crab Run anticlinal axis. The gas-bearing structure is complicated by several minor folds, which parallel the major axis, and by three relative cross-folds. Though limited in extent northeast of Bergton, the anticline appears to be continuous with a large anticlinal complex 25 miles southwest. Local doming along the axis should present favorable areas for future exploration.