The Blue Ridge and Piedmont have the oldest rocks (about 1 billion years), and the Piedmont also includes younger rocks of Paleozoic age (Cambrian to Pennsylvanian, 550-300 million years). The Plateau and the Valley and Ridge are entirely Paleozoic. These rocks were laid down and disrupted during the opening and closing of at least one ocean where the Atlantic is today. These tectonic events led to widespread faulting and thrusting that has placed older rocks above younger ones in many places.
The Atlantic began to open during the Triassic (about 200 m.y.), and the teal-and-orange blobs in the Piedmont are stretch marks in the continent from that time, filled with volcanic rocks and coarse sediments. As the ocean widened the land settled down, and the young rocks of the Coastal Plain were laid down in the shallow offshore waters. These rocks are exposed today because ice caps hold water out of the ocean, leaving sea level unusually low.
Virginia is full of geologic resources, from coal in the Plateau to iron and limestone in the mountains to sand deposits in the Coastal Plain. It also has notable fossil and mineral localities. See a gallery of Virginia geological attractions..
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