GEOLOGY OF THE BLUE RIDGE REGION IN CENTRAL VIRGINIA
The Blue Ridge region in central Virginia extends from the southeastern margin of the Valley and Ridge province across the Blue Ridge into the Piedmont province. Across this span formations are sequentially continuous, so the Precambrian formations of the Piedmont are conformably related to the Cambrian formations of the Valley and Ridge. Extensive exposures of the Early Cambrian Chilhowee group reveal lithologic and facies variations that suggest certain geosynclinal relations and inconsistency in the use of several sets of formation names. The overlap of the Late Precambrian including the Catoctin greenstone, classified as spilite, and the relations of the Chilhowee group define a eugeosyncline to the east and a miogeosyncline to the west separated by an undation along which the Blue Ridge eventually formed. The Catoctin Mountain-Blue Ridge anticlinorium is described as an epeirogenic uplift instead of a complex flexure fold. A dominant cleavage, independent of folding, is recognized as a thrust cleavage related to faulting.