<P> Most of the rocks that form the Blue Ridge Mountains are ancient granitic charnockites, metamorphosed volcanic formations, and sedimentary limestone . Recent studies completed by Richard Tollo, a professor and geologist at George Washington University, provide greater insight into the petrologic and geochronologic history of the Blue Ridge basement suites . Modern studies have found that the basement geology of the Blue Ridge is made of compositionally unique gneisses and granitoids, including orthopyroxene - bearing charnockites . Analysis of zircon minerals in the granite completed by John Aleinikoff at the U.S. Geological Survey has provided more detailed emplacement ages . </P> <P> Many of the features found in the Blue Ridge and documented by Tollo and others have confirmed that the rocks exhibit many similar features in other North American Grenville - age terranes . The lack of a calc - alkaline affinity and zircon ages less than 1,200 Ma suggest that the Blue Ridge is distinct from the Adirondacks, Green Mountains, and possibly the New York - New Jersey Highlands . The petrologic and geochronologic data suggest that the Blue Ridge basement is a composite orogenic crust that was emplaced during several episodes from a crustal magma source . Field relationships further illustrate that rocks emplaced prior to 1,078 - 1,064 Ma preserve deformational features . Those emplaced post-1,064 Ma generally have a massive texture and missed the main episode of Mesoproterozoic compression . </P> <P> The Blue Ridge Mountains began forming during the Silurian Period over 400 million years ago . Approximately 320 Mya, North America and Europe collided, pushing up the Blue Ridge . At the time of their emergence, the Blue Ridge were among the highest mountains in the world, and reached heights comparable to the much younger Alps . Today, due to weathering and erosion over hundreds of millions of years, the highest peak in the range, Mount Mitchell in North Carolina, is only 6,684 feet high--still the highest peak east of the Rockies . </P> <Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (August 2014) (Learn how and when to remove this template message) </Td> </Tr> </Table>

What event most likely created the blue ridge mountains in virginia
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