Geology of Virginia

Throughout the Proterozoic and Paleozoic, Virginia experienced igneous intrusions, carbonate and sandstone deposition, and a series of other mountain-building events which defined the terrain of the inland parts of the state.

The closing of the Iapetus Ocean formed the supercontinent Pangaea, and created additional small landmasses, some of which are now hidden beneath thick Atlantic Coastal Plain sediments.

The region subsequently experienced the rifting open of the Atlantic ocean in the Mesozoic, the development of the Coastal Plain, isolated volcanism, and a series of marine transgressions that flooded much of the area.

In Roseland, between Charlottesville and Lynchburg, is a nine-mile-long intrusion of the 90 percent plagioclase feldspar rock anorthosite, the formation of which remains poorly understood by geologists.

Magma ascended through the crust, but stopped due to a high-density zone and through a process of fractional crystallization, cooled to form basalt.

To the west of the Blue Ridge, the Chilhowee Group sandstones formed thick sequences, recording a beach environment in Iapetus Ocean.

However, the Iapetus Ocean was still closing, adding additional small terranes to the region, including one which is likely concealed by Coastal Plain sediments.

[6] In the Paleocene period of the Cenozoic, high sea levels from the Cretaceous dropped, bringing an increase in terrestrial erosion.

The component Aquia and Nanjemoy formations contains sand, clay, small gypsum crystals, green glauconite grains as well as fossils.

[7] Sea levels dropped again during the Oligocene, only to return to widespread inundation during the Miocene and Pliocene, depositing the two cycles of the Chesapeake Group.

Cornwallis Cave is eroded into the cross-bedded coquinas of the Yorktown formation, along with the sea cliffs at Westmoreland State Park (which also exposes underlying Eastover and Choptank rocks).

The surficial Shirley formation, beneath what is now Newport News and Hampton, deposited during the Middle Pleistocene, reaching the York and James River estuaries.

[9] In colonial times and earlier periods of American history, Virginia had active mining for lead, zinc, gold, and titanium.

Willis Mountain, near US 15 between US 60 and US 460 hosts the largest kyanite mine in the world, supplying the automotive spark plug and high-temperature kiln industry.