Origin of the Appalachian Orogen, a result of three separate continental collisions involving the North American Continent with the Taconic and Acadian terranes, and finally the collision of the African and North American continents during the Alleghenian Orogeny at the end of the Paleozoic. - USGS

http://3dparks.wr.usgs.gov/nyc/images/fig53.jpg also http://3dparks.wr.usgs.gov/nyc/common/captions.htm

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