Are there any igneous rocks in West Virginia?
There are no granite bodies exposed in West Virginia. Workers from the Survey have identified a number of “shallow,” intrusive igneous dikes, sills, and plugs with compositions ranging from basalt to andesite that cut across sedimentary rocks of Ordovician through Devonian age. These rocks are exposed at the surface in Pendleton County and are reported in subsurface well drilling records from other counties such as Pocahontas. These dikes, sills, and plugs are younger than the rocks they cut. Research by the U.S. Geological Survey and others indicate that the majority of these igneous intrusive rocks are Middle Eocene in age and thus, are considerably younger than the last stages of mountain-building associated with the Appalachian Orogeny or the Mesozoic rifting that opened the present-day Atlantic Ocean. During the Middle Eocene, the eastern coast of North America is thought to have been a “passive” continental margin, much like today. The presence of igneous activity in such a setti
