The Valley and Ridge province lies west of the Blue Ridge. Its pattern of long, parallel ridges separated by valleys gives the region its name.
Quick answer: The Valley and Ridge region of Virginia is a belt of long, parallel ridges and valleys made of folded sedimentary rock about 520 to 300 million years old. Its eastern part, the Great Valley (including the Shenandoah Valley), rests on limestone and similar rocks full of caves.
Contents
Ridges and Valleys
The province is made of folded sedimentary rocks of the Paleozoic era. The oldest layers are about 520 million years old (Cambrian) and the youngest about 300 million years old (Carboniferous).[1] The rows of ridges run along the western side of the state.[2]
The Great Valley
The Great Valley, which includes the Shenandoah Valley, sits on a thick sequence of carbonate rock such as limestone. These rocks formed in a shallow tropical sea on the southeastern edge of ancient North America.[1]
Carbonate rock dissolves slowly in water. As a result, karst (a landscape of sinkholes, springs and underground drainage) is typical of the Great Valley, and many caverns lie below the surface.[1] At Natural Chimneys, in the Shenandoah Valley, Cambrian carbonate rocks stand exposed above the ground.[1]
Fossils of the province include brachiopods, trilobites, corals, graptolites and snails, most of them from the Paleozoic era.[2]
How the Rocks Were Folded
About 450 million years ago, mud and sand eroded from highlands raised to the east during the Taconic mountain-building event. Carbonate layers were laid down again later, in the Silurian period.[1]
The ridges took shape during the late Paleozoic collision of continents known as the Alleghanian orogeny. The rocks were folded and pushed westward along thrust faults. In western Virginia the crust was shortened by 40 to 70 percent.[1]
Frequently asked questions
Where is the Valley and Ridge region of Virginia? West of the Blue Ridge, along the western side of the state.
Is the Shenandoah Valley part of the Valley and Ridge? Yes. It is part of the Great Valley, the eastern section of the province.
Why are there so many caves in the Valley and Ridge? The Great Valley rests on limestone and similar rocks that dissolve in water, forming karst and caverns.
How old are the rocks of the Valley and Ridge? From about 520 to about 300 million years old.
References
- [1] The Geology of Virginia (William and Mary), Valley and Ridge – last checked 11/08/2026
- [2] Virginia Energy, Geology and Mineral Resources: Virginia Provinces and Fossils – last checked 11/08/2026
The other provinces are described in The Regions of Virginia.