Virginia has grown in size over the last 2 billion years. Volcanoes spewed lava onto the surface, oceans deposited sediments, continental collisions added clumps of land, and sediments eroded from uplands to form new land at the edge of the waters (or underneath the water). We also shrank: continental collisions pushed rocks over each other and folded up Virginia like an accordion, and erosion has washed away the land particle by particle.
That's the basic process, and it affected the entire eastern coast of North America. The crystalline bedrock underneath the more-recent limestone in Florida was once part of Africa, for example. That bedrock was part of Gondwana (the African plate), before it smashed into Laurentia (the North American plate) to form Pangea. When the continents split up, the Florida chunk of the African plate was left behind, attached to North America.1
Now put on your thinking cap and follow the links below.
(Whew, did you look at all three? Long description, lots of words... and it's only a short, not-exactly-perfect abbreviated version. Considering that you covered 1.8 billion years in a few minutes, that's a pretty good compression ratio.)
