The Geology of Virginia's Valley and  Ridge
F O R   S T U D E N T S   &   T E A C H E R S

Landform indicative of the Virginia Valley and
Ridge geologic province

T

he Valley & Ridge province is made up of long parallel ridges and valleys with folded Paleozoic sedimentary rock A below and inside them. The valleys and ridges were produced when bands of rocks, which were folded and faulted, eroded differently. Cambrian-aged sandstones (540 million years-old) from the western Blue Ridge are overlain by carbonates that made up a big region of limestone and dolomite called the Great American Carbonate Bank. For at least 70 million years carbonates were deposited in a shallow tropical ocean along the southeast edge of North America. Today these carbonates (up to 3.5 kilometers in thickness) are exposed in the Great Valley (as known as the Shenandoah Valley in central and northern Virginia), the easternmost portion of the Valley & Ridge province. Well-developed caves and sinkholes can be found in the Great Valley.

Geologic Events in the northern and central Virginia Valley and Ridge

By middle Ordovician time, sand and gravel washed down from new mountains pushed up to the east of the Valley & Ridge. By late Ordovician and Silurian, the sand and gravel turned into rocks, and record the uplift and erosion of the Taconic Mountains. By the late Silurian, carbonates were again being deposited in the area. The sediment deposition continued from the Silurian through the Carboniferous (the Mississippian & Pennsylvanian) in the Valley & Ridge and Appalachian Plateau) and record pulses of uplift & mountain building to the east. Continental collision in the late Paleozoic produced a fold and thrust belt which thrust Blue Ridge rocks to the northwest on top of the Paleozoic rocks B. Paleozoic sedimentary rocks of the Valley & Ridge were also folded and moved westward along thrust faults C.