Sunday, March 20, 2016

Explore Great Smoky Mountains’ geology

The highest points of the Great Smoky Mountains consist of
erosion-resistant metasandstone.
One billion years ago, the area that now is the Great Smoky Mountains sat in an ocean at the edge of the North American continent. As clay, mud, sand and silt eroded off a nearby highlands, they filled the water, forming a layer nine-miles thick.

Much of the rock currently at the national park’s surface are sedimentary layers that piled atop that layer over a span of 95 million years beginning about 545 million years ago. Fossils of sea creatures – burrows of worms and shells of crustaceans – can be found in these sedimentary layers at the park, most notably Cades Cove.

About 310 million years ago, the North American and African tectonic plates crashed into one another. For the next 65 million years, this grinding of plates pushed up land all along the North American coastline, creating the Appalachian Mountains, which stretched from Newfoundland to Alabama. At one time, the Appalachians stood as high as the Rocky Mountains do today.

As the two tectonic plates separated and moved to their current positions, erosion began to tear down the Appalachians. Rivers and streams moved the sand and silt to the Atlantic Ocean and Gulf of Mexico; in fact, some of today’s Gulf of Mexico beaches are made of eroded rock from what is now the Great Smoky Mountains.

The most resistant of those rocks – metasandstone – remain the park’s highest peaks. The majority of waterfalls occur at metasandstone ledges.

In the millennia ahead, the Great Smoky Mountains eventually will erode away. Geologists estimate the park is losing about an inch of elevation every 500 years.

Some great spots to explore the park’s geology include:
Chimney Tops Trail
Clingmans Dome Trail
Rainbow Falls Trail

Learn about other great trails at this national park in Best Sights to See at Great Smoky Mountains National Park.