The Belair Exploratory Trench #10-76 was dug in October,1976, for the purpose of testing the conclusions of Prowell, O'Connor, and Rubin, 1975, and O'Connor and Prowell, 1976, concerning the time of latest movement along the Belair fault zone. The trench site is located 800 meters (2600 ft.) S27°W of the old Belair railroad station on U.S. Route 1 & 78 (see inset on Plate 1) in the southernmost clay pit of the Georgia Vitrified Brick and Clay Company. The trench was oriented almost nor-mal to the strike of the Belair fault zone (N27°E) about 100 meters (330 ft.) south of the trench exposure reported by Prowell, O'Connor, and Rubin, 1975. In this report, we are maintaining the terminology of Prowell, O'Connor, and Rubin, 1975, in defining the main fault as the fault that juxtaposes the crystalline phyllites and the Coastal Plain sediments (Plate 1 - at meter 106). Similarly, we refer to the eastside of the Belair fault zone as the upblock and the west side as the downblock.

Georgia↗

USGS1976

Detailed investigation of a coastal plain-Piedmont fault contact in northeastern Virginia

A trench across the Dumfries fault of the Stafford fault zone near Stafford, Virginia (see Mixon and Newell, 1976) exposed a high-angle reverse fault juxtaposing Paleozoic Quantico Slate and Cretaceous Potomac Group rocks. A system of subsidiary reverse faults and small scale normal faults disrupt the Coastal Plain strata adjacent to the main fault. Cross-cutting relations and stratigraphic details indicate that the subsidiary faults in the Cretaceous rocks document a history of episodic deformation, in part active during accumulation of the Coastal Plain strata. Slickensides and stereo net analysis of theorientation of subsidiary reverse faults, normal faults, and bedding indicate that, through time, faulting consistently included right lateral separation.

Virginia↗

USGS1976

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.

Open-File Report↗

USGS1975