Preliminary investigation of faults and folds along the inner edge of the coastal plain in northeastern Virginia

Four en-echelon northeast-trending structures, including southeast-dipping monoclines and northwest-dipping high-angle reverse-faults, have been mapped along the inner edge of the Coastal Plain in northeastern Virginia -- an area generally considered to be undeformed. Although displacements are small (15to 60 m), the structures markedly affect the present distribution and thickness of Coastal Plain strata. Structure contour maps on Cretaceous and Paleocene lithostratigraphic units show that the amount of displacement on the structures increases downward, indicating recurrent movement. The major deformation occurred in the Cretaceous and middle(?) Tertiary but some movement in the latest Tertiary or Quaternary is possible.

The structures, herein named the Stafford fault system, extend for at least 56 kilometers parallel to the Fall Line and the northeast[trending reach of the Potomac estuary. This relationship-supports the hypothesis that the Fall Line and major river deflections along it have been tectonically influenced.