Field mapping of crest and trough lines of the larger folds clarifies the junction between central Appalachian structural trends (striking about N25°E) and southern Appalachian trends (striking about N65°E) in southeastern West Virginia and adjacent Virginia. Previous interpretations have argued whether the change in orientation is gradual or abrupt, whether the two trends formed simultaneously, whether the more obviously overthrust southern Appalachians overrode the central trend, whether the central Appalachians were overprinted across the southern trend, whether the junction of the two trends is caused by rotational movement, or whether the differences result from a major basement fracture zone separating the two blocks.

Our mapping shows that the folds are continuous across the junction of the trends, with a gradual bending of the fold traces. For tens of miles north of the junction of the two trends, gentle folding striking about N35°E can be mapped within the relatively flat major synclines of the central Appalachian area, but cannot be readily traced into the steeper flanks and more sharply folded crests of the major anticlines. We believe that these gentle anticline folds trending N35°E are related to the initial folding of the southern segment that trends N65°E. Subsequent to the development of the southern Appalachian folds, the central area was simultaneously folded and rotated, reorienting the northern extension of the southern fold generation to their present position of N35 76;E. This suggests that the southern fold and fault trend was overprinted by the central trend, a conclusion consistent with studies of stylolites by Dean and Kulander. Near the junction of the central and southern trend, structural domes and depressions formed as a result of fold interference.

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