The Smoky Mountains are part of the Appalachian Mountains, which stretch from Georgia to Canada. The Smoky Mountains are part of the Blue Ridge province, named for their characteristic bluish haze. The rocks that form the Smoky Mountains range in age from 350 million years ago (Early Mississippian) to over 1 billion years ago. Their characteristic shape is the result of millions of years of erosion that has taken place from the late Mesozoic to today.
The rocks that make up the mountains originated as sediment that was deposited in a shallow sea located between the continents in the Precambrian. This sediment accumulated for millions of years and then around 200 million years ago (during the Jurassic Period) the North American and African continents collided together to form the Smokies during the Appalachian orogeny. (An orogeny is a mountain-forming event where the earth's crust is compressed together.) This orogeny caused much of the strata to become folded, faulted, fractured and metamorphosed. Large thrust faults developed during the orogeny, moving much older Precambrian bedrock up and over the younger Paleozoic strata. The Great Smoky fault, located on the western edge of the park, is one of these large thrust faults.
There are three types of rocks that make up the park. The oldest rocks are those of the Precambrian basement complex. These rocks are over 1 billion years old and are composed of gneiss, schist, (metamorphic rocks) and some granite (igneous rocks). These basement rocks are so named because they form the foundation under the mountains upon which all the other rocks have been deposited. These rocks are only exposed in the southern and eastern portions of the park (North Carolina side), and in other areas of the mountains outside of the park.
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