Date of Graduation
1966
Document Type
Dissertation
Abstract
The Great Valley (Shenandoah Valley) of eastern West Virginia is the northern extension of the Shenandoah Valley of Virginia and marks the eastern limit of the Valley and Ridge physiographic province. The valley is underlain by nonresistant carbonate rocks and shales of Cambrian and Ordovician age, which have been eroded to produce a relatively flat to rolling terrain. The surface geology of the Great Valley is dominated by the north-northeast trending Massanutten synclinorium. The axis of this structure coincides with a belt of Martinsburg Shale west of the center of the valley. The western limb of the Massanutten synclinorium is in fault contact with the Silurian-Devonian formations of North Mountain. Near the Blue Ridge, the eastern limb of the synclinorium is coincident with the western, overturned flank of the South Mountain anticlinorium. Folds superimposed upon the basic structure of the synclinorium are asymmetric to the west and overturned to a near-recumbent position at many places near the Blue Ridge; cleavage dips gently eastward in a fan arrangement. Progressively westward, the axial planes of folds become more steeply inclined, and in the western belt of the valley, folds are generally symmetrical with vertical cleavage fans. High-angle and low-angle longitudinal faults are present in the central and western parts of the valley but are, as yet, undetected in the eastern part of the valley. High-angle transverse faults are common throughout the valley. A progressive decrease of gravity values to the west from the vicinity of the Baltimore dome suggests that gravity sliding was involved in the deformation of the Blue Ridge and Great Valley. The uniformity of the gravity gradient and the similar densities (approximately 2.70) of the granitic gneiss basement and the younger sedimentary rocks indicate that folds have no “roots” in the simatic layer of the basement. Deformation of the rocks of the Great Valley and Blue Ridge was the result of the Appalachian Revolution and probably occurred in four major phases. Intensive folding with attendant cleavage development marked the first phase. Thrust faults and high-angle, longitudinal, reverse faults characterized the second phase. Transverse shear faults developed and offset previous structures during the third phase. Deformation ended after a fourth, or “relaxation,” phase, which is represented by longitudinal and transverse normal faults.
Recommended Citation
Dean, Stuart Linden, "Geology Of The Great Valley Of West Virginia." (1966). Graduate Theses, Dissertations, and Problem Reports. 8729.
https://researchrepository.wvu.edu/etd/8729