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This article is from the Encyclopedia of North Carolina edited by William S. Powell. Copyright © 2006 by the University of North Carolina Press. Used by permission of the publisher. For personal use and not for further distribution. Please submit permission requests for other use directly to the publisher.

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by William G. DiNome, 2006Ashe formation. Image courtesy of the McKinney Geology Teaching Museum, Appalachian State University.

The geologic record suggests volcanic activity in what is now North Carolina primarily occurred in two phases of the middle Proterozoic era, between 850 and 500 million years ago, first while the ancient North American and Euro-African plates were moving apart, then while these same plates were colliding. During the first phase, 840 to 800 million years ago, eruptions occurred under the ancient Iapetus Sea and on land. Volcanic ash and lava flows deposited underwater and interbedded with layers of mud and sand are now part of the Ashe Formation stretching from Ashe and Watauga Counties in North Carolina into Franklin County, Va. The first eruptions on land occurred about 820 million years ago on the Piedmont Terrane, along the present North Carolina-Virginia border in the environs of Mount Rogers. These eruptions continued for at least 220 million years and deposited some 3,000 meters of volcanic and sedimentary rock.

The second phase of volcanic activity, beginning around 750 million years ago and lasting more than 300 million years, occurred along an arc of island volcanoes on the Avalon Terrane, a collision zone between the Iapetus Sea and the Theic-Rheic Ocean. Intense folding and metamorphism have destroyed most evidence of these eruptions, but the rocks created are present in the Carolina State Belt stretching southward through the midsection of the state. The eastern boundary of the belt is undetermined as it lies beneath the Coastal Plain, while the western boundary roughly passes near Greensboro, Thomasville, Lexington, Salisbury, Charlotte, and into South Carolina. Remnant volcanic necks and masses of igneous rock are evident in Orange and Chatham Counties, suggesting an early center of volcanic activity near Chapel Hill, dated at around 700 million years old, and near Hillsborough, dated at about 650 million years old.

Volcanic eruptions may have occurred during the middle Eocene epoch, about 47 million years ago, in the northern and western regions of the state, but erosion has removed all cones or other evidence of such activity. Also, volcanic ash deposits (bentonite) in the Castle Hayne Formation in the Coastal Plain are not believed to be native to the region, but possibly deposited by winds from a volcanic center in Virginia or from eruptions forming the island of Bermuda. There are no known active volcanoes in North Carolina today despite some geologic instability on the coast.



Fred Beyer, North Carolina, the Years before Man: A Geologic History (1991).

Mary-Russell Roberson and Kevin G. Stewart, The Geologic Story of the Carolinas: A Field Guide (2006).

Additional Resources:

Geological Society of American, Bulletin of the Geological Society of America, volume 20.

Stewart, Kevin G., and Mary-Russell Roberson. 2007. Exploring the geology of the Carolinas: a field guide to favorite places from Chimney Rock to Charleston. Chapel Hill: University of North Carolina Press.

Image Credit:

Ashe formation. Image courtesy of the McKinney Geology Teaching Museum, Appalachian State University. Available from (accessed July 30, 2012).



Is Table Rock a dormant volcano? When you climb to the top you will see the rock looks like it had been poured out of something. There are directional flow patterns and smooth rolls in the rock. It reminds me of the mesas found in the Western part of the country.


i think volcanoes are sometimes fun to watch


i noticed a layer of what i believe is volcanic ash in a profile section of a dirt bank being excavated while on a construction site in Johnston County near Clayton, NC. can anyone tell me how long it has been since an eruption occurred in this part of the US? this layer is about 7-9' deep under a thick layer of weathered rock and clay/sand sediment. thanks SW


I've seen evidence of volcanic activity in clayton too. Closer to garner. That's what lead me here.


We had a school tour at Emerald Hollow. The geologist onsite stated that Lowes Motor Speedway was built on a caldera. However, I cannot find information to confirm this information. Before I teach kiddos this information at school, I want to be certain it is accurate. Can you help me? Thank you!


I grew up in concord as well and they use to take us on nature walks around the campus of middle school explaining how there was a volcanoes around there. So there has to be information somewhere. I would ask a question.


I grew up in Concord went to Northwest Cabarrus High where they taught us this fact. I am sure they still have the old history books from the 90's


Hi, Angelique.

Thank you for your question. This short Q&A section in the Atlanta Journal Constitution addresses this question, but doesn't really clarify the question:

I think the takeaway is that the area long ago was the site of volcanic activity, but I was not able to find any information definitely locating a caldera beneath the track. 

I hope this is helpful.

Mike Millner, Government & Heritage Library


Hello, my family and I are vacationing on the outer banks this year and I noticed that is quite a lot of black sand on the surface of the beach and underneath. My mother thought this might be due to underwater volcanic activity. We usually vacation on Oak Island, which is not to far from here and I've never seen black sand there. I'm wondering if you can solve this predicament for me, thank you!


Hi, Bailey.

Thank you for this great question. I learned something new.

UNC Press published a book in 2004 titled How To Read a North Carolina Beach. The black sand in question might be "heavy-mineral sand," which can become concentrated when the lighter quartz sand is blown away by the wind. You can read more here (starting on page 29:

I hope this helps you answer your question.

Mike Millner, NC Government & Heritage Library

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