The Blue Ridge, which forms the extreme eastern member of the Appalachian Mountains, constitutes one of the principal topographic divisions of the Appalachian ranges. In Virginia the Blue Ridge Mountains form a fairly continuous and well defined ridge extending from Harpers Ferry southwestward entirely across the State. At Harpers Ferry the Blue Eidge Mountains are narrow, and in elevation are less than 1,000 feet above sealevel; but southwestward through Virginia the ridge becomes broader and higher, and attains its greatest width in North Carolina. Heights of more than 4,000 feet above the sea are reached at several points in Virginia.
The Blue Ridge is composed of a central core of igneous rocks, flanked on the northwest side by the folded sedimentary series of Cambro-Ordovician rocks of the Great Valley province. The basal member of this series is a quartzite (Weverton), which extends for much of the distance as a . . .