Complex sentence: The oldest known rock found in Georgia comes from the dun town era and is about 1 to 1.3 billion years old and is found in the Piedmont Plateau and Blue Ridge mountain regions.
Split into simpler sentences: The oldest known rock found in Georgia comes from the dun town era and is about 1 to 1.3 billion years old. It is found in the Piedmont Plateau and Blue Ridge mountain regions.