The Fall Zone delineates the boundary between the Coastal Plain and the Piedmont.  Here rivers draining the Piedmont drop steeply to sea level and in the process form dramatic rapids.  

The Neoproterozoic Lynchburg Group is a thick sequence of metasedimentary rocks exposed in the eastern Blue Ridge from northern to south-central Virginia.  These deposits range from coarse-grained conglomerate to fine-grained mudstone.