MadSci Network: Earth Sciences |
The Great Smokey Mountains are primarily composed of Precambrian age metamorphic rocks. Those rocks began as sedimentary rocks, shales (layers of mud), sandstones (layers of sand), and conglomerates (layers of gravel). They were deposited in an ocean basin between about 800 million years ago and 550 million years ago. They were buried deeply under more sediments and then they were heated up and folded up as part of a major mountain building event called the Alleghenian orogeny, about 250 million years ago. In this event, the rocks were metamorphosed into phylites, schists, and quartzites that now make up the bulk of the Great Smokey Mountains. For more detail and a map showing where the rocks are, see: http://www.uwm.edu/Course/geosci697-tectonic/GroupD/IntroPage/IntroPage.html The USGS also has a lot more detailed information in a Professional Paper: http://pubs.usgs.gov/of/2005/1225/ David Smith Da Vinci Science Center
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