ENGLUND, KENNETH J., ROGER E. THOMAS, and JOHN B. ROEN, U.S. Geological Survey, Reston, VA

ABSTRACT: Geology of the Cumberland Gap Area, Kentucky, Tennessee, and Virginia

Recent attempts to correlate Upper Mississippian and Lower Pennsylvanian strata traversed by a highway tunnel on the southwestern side of Cumberland Gap with counterparts on the northeastern side of the gap have been hampered by left-lateral displacement on the intervening Rocky Face fault. Strike-slip movement of at least 1.5 mi has placed contrasting stratigraphy in juxtaposition. For example, the Little Stone Gap Member of the Hinton Formation, a widespread marine bed, and much of the underlying Stony Gap Sandstone Member of the Hinton are truncated at the base of the Pinnacle Overlook Member of the Lee Formation on the northeastern side of the gap. However, in the tunnel section, both members of the Hinton are present and the overlying Pinnacle Overlook Member is split into two co glomeratic sandstone beds. In the tunnel section, the succeeding Bluestone Formation, readily recognized by the presence of varicolored shale, contains marine fossils reported to be Pennsylvanian in age. Regionally, Mississippian marine fossils occur in the Bluestone and Pennsylvanian plant-impression fossils, notably Neuropteris pocahontas, occur in upper beds of the formation; these fossils are the basis for classifying the Bluestone as Mississippian-Pennsylvanian in age. Strata above the Bluestone are in the Pennsylvanian part of the Lee Formation and at the tunnel include the (1) Chadwell Gap Member, mostly conglomeratic sandstone about 130 ft thick, (2) Dark Ridge Member, dark-gray shale and ripple-bedded sandstone about 40 ft thick, (3) Middlesboro Member, mostly conglomeratic sand tone about 400 ft thick, and (4) lower part of the Hensley Member.

AAPG Search and Discovery Article #90995©1993 AAPG Eastern Section Meeting, Williamsburg, Virginia, September 19-21, 1993.