The Broadtop synclinorium is a large regional synclinorium which extends from central Pennsylvania to western Virginia. It is the most western of the synclinoria in the Valley and Ridge province, and locally may extend to within 15 mi of the Allegheny Front. Although the synclinorium is broken into a series of folded and faulted structures, its basic structural style reflects both basement movement and thin-skinned tectonics. More than 125 mi of seismic surveys, 22 wells, and surface maps were analyzed to determine the precise relation of basement to thin-skinned tectonics. This relation, as interpreted, indicates that Taconic and older, tension-induced features have a pronounced effect on the localization and genesis of the ramping of decollements. This ramping, in turn, produces many of the large, prominent, first-order structural features in both the Valley and Ridge, and the Plateau provinces of the Appalachian basin. The Allegheny Front is an example of such a feature. The decollement ramping also induces formation of smaller, second-order features such as the Whip Cove anticline, the Whip Cove syncline, and other flexures and faults within the Broadtop synclinorium.