Geology of West Virginia

At times, much of what is now West Virginia was covered by swamps, marshlands, and shallow seas, accounting for the wide variety of sedimentary rocks found in the state, as well as its wealth of coal and natural gas deposits.

West Virginia has had no active volcanism for hundreds of millions of years, and does not experience large earthquakes, although smaller tremors are associated with the Rome Trough, which passes through the western part of the state.

This Grenvillian basement rock underlies substantially all of the Appalachian region, from the Ohio valley to the sea, and extends north and south into eastern Canada and Mexico, as well as a part of the Scottish highlands.

To the west, they are hidden beneath the Valley and Ridge and Appalachian Plateau, while to the east they extend under the Piedmont, coastal plain, and continental shelf.

The rifting process thinned the crust and led to volcanic activity, resulting in a layer of basalt, today known as the Catoctin formation, burying the existing ridges and valleys.

During this total interval of about 370 million years, most of the rocks today exposed in Jefferson and eastern Berkeley counties and in scattered areas southwestward along the boundary were deposited.

This condition prevailed for more than fifty million years, resulting in the deposition of thousands of feet of non-marine sandstone and shale, as well as the many important coal seams that we know today.

During Middle and Late Devonian time the Acadian Orogeny, with the main uplift to the northeast, resulted in a further source for the predominantly clastic marine deposits of these epochs.

Early in the succeeding Pennsylvanian Period, the area dropped to near sea level and for more than 50 million years continued to sink at about the same rate that deposition was taking place.

In other parts of world, rocks of this age, which extended from 225 to 66 million years ago, contain the remains of countless species of dinosaurs and other reptiles; such fossils are virtually unknown in West Virginia.

Approximately 45 million years ago, a complex of dikes and sills with compositions ranging from basalt to rhyolite were intruded into the Paleozoic sedimentary rocks in the area in and around Pendleton County.

The oldest evidences of life found in West Virginia occur in rocks about 600 million years old, in the Antietam Formation of Lower Cambrian age.