Monday, March 28, 2011

The Largest Granite Quarry on Earth

TB and I decided to scrap a visit to Reynolda House Museum Saturday for a short day trip as we hadn’t been out of Greensboro since the beginning of February. First, I got sick and then TB got sick and neither one of us wanted to travel anywhere. Instead we stayed home and moped and complained about how bad we felt.

So back on the road again for a short trip up through Mount Airy and into Virginia.

I spotted a sign for the North Carolina Granite Quarry and took a quick swing up to its observation area. I only had the little camera with me (I lost the lens cap Thursday for the big camera while I was taking my sunset photos and am waiting for a replacement one).

Mount Airy is home to the largest open face granite quarry in the world. There are larger pit quarries throughout the world but no larger open face quarries. A pit quarry is below the surface, while an open face quarry is at ground level.

Shaped like an enormous oyster shell, the quarry covers approximately 90 acres, which is currently under operation. The deposit is about 1 mile long and 1/3 mile wide. Geological mapping shows the total mass to be about 7 miles by 4 miles and 6,000 to 8,000 feet deep. Since 1889, the quarry has been in full operation, and the surface has only just been scratched according to depth tests. Geologists say the deposit can be quarried for approximately 500 more years without exhausting the supply.

Because the granite has no natural beds and cracks, it is necessary to free great sheets of granite from the mass by a process called lifting. Dynamite is never used for quarrying. The results of its use would be disastrous because its force would shatter and crack the granite, which would cause flaws. Instead, black gun powder is used.

The story goes that the world’s finest natural quarry changed hands for nothing. In 1872, a farmer named John Gilmer purchased several thousand acres of farm and woodland covering what is now part of Mount Airy and much of the Flat Rock community. One of his friends learned the tract of land contained 40 acres of bare rock. Mr. Gilmer immediately went to the seller and threatened to back out on the deal because of the worthless 40 acres. The seller agreed to deduct the 40 acres of worthless rock in calculating the dollar value of the whole tract. Therefore, the quarry exchanged hands for nothing.

About 17 years later, a firm of builders, Thomas Woodruff & Sons, was building railway stations in the area. They recognized the potential value of a granite quarry and bought John Gilmer’s “worthless” rock for $5,000. 

The quarry is so large that it can be seen by astronauts in outer space!

The quarry operates seven days a week. While we didn’t hear or see any explosions, we were almost run off the road to the observation area by one of the largest forklifts I’ve ever seen.


frayedattheedge said...

Amazing!! I guess we never really give a thought to where things cme from!

Anyes said...

Interesting how someone's worthless rock rewarded its owner with so much money. Thank you for all your researching, Karen :-)

Scrappy Grams said...

That's amazing, both the story and how long granite can be mined from there!

Karen said...

Anne: Thank you. I think your part of the world is amazing and my state is just full of prosaic things, none of which are quite that interesting. But, sometimes they are.

Anyes: The quarry has supplied granite all over the world, but was turned down for the 9/11 Memorial. Would you believe it went to an Italian company?

SG: This blog is helping me find some really interesting things (at least to me). I'm glad I can share them with you.

Alex saude said...

Muito bonita a sua foto da pedreira de granito! Trabalho nessa area no Brasil, inclusive eu vendo granito Brasileiro para os EUA, tenho muito orgulho disso! God bless u, Brasil and America!