Inside N.C. Science

NC had run-ins with volcanoes millions of years ago

CorrespondentMarch 16, 2014 

Dr. Chris Tacker is research curator of geology at the N.C. Museum of Natural Sciences.

N.C. MUSEUM OF NATURAL SCIENCES

The Tambora volcano exploded in 1815, in the faraway islands of Indonesia, yet its impact was felt globally. The eruption sent ash 26 miles high, into the upper atmosphere and ultimately around the world. The following year saw crop-killing frosts in New England as far south as New Jersey; June snows in Quebec, New York and Maine; and Europe’s last great subsistence crisis. In North Carolina, the Moravians’ records showed their crops failed almost completely. The next year, 1816, was the “Year Without A Summer.”

Volcanic ash is nasty stuff – highly abrasive and with a bit of an electrical charge to it. The last big eruptions from California’s Long Valley caldera or from Yellowstone were larger than Tambora, capable of dropping enough ash downwind to wipe out crops and shut down the electrical grid (transformers can’t handle ash well; they can short out).

Computers must be shut down because ash plays havoc with hard drives and motherboards: Computers’ helpful little cooling fans pull the ash right in. Last time I went to the Soufriere Hills Volcano on the Caribbean island of Montserrat, I took a roll of plastic wrap to cover my laptop … just in case.

It’s a good idea to study volcanoes here and worldwide. Minerals within volcanic rocks record everything that happens in and below volcanoes, and my research is geared toward pulling out all of the information in that record.

I don’t have to go very far from Raleigh to work on a volcano. The Carolina terrane, now much of the central and eastern Piedmont, was an active volcanic island arc 500 million to 600 million years ago. It is an exotic terrane, formed elsewhere and added to North America later. The Carolina terrane brought with it some exotic species, too – important soft-bodied organisms and trilobites that were foreign to North America at the time.

If you want to see volcanic rocks in North Carolina, go to Morrow Mountain State Park or Dave’s Mountain in Asheboro. Purgatory Mountain at the south end of the North Carolina Zoo parking lot is an ash flow from a long-extinct volcano. Just about everything around Chapel Hill formed around (or under) one of these volcanoes. The land around Charlotte is the deep underground plumbing of these volcanoes, while around Raleigh are the upper parts.

Despite popular opinion, Pilot Mountain isn’t volcanic.

North Carolina is nice and peaceful today. Without the eyes of a geologist, you would never know that it was once hazardous to live here.

Dr. Chris Tacker is research curator of geology at the N.C. Museum of Natural Sciences.

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