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Natural Staircase

 
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Natural Staircase
This is one of the most interesting features along the Ridge Trail on Old Rag. The "steps" are actually examples of columnar basalt joints, seemingly out of place on a mountain composed mostly of hard, slick granite.

Shenandoah NP, VA-- January 21, 2008

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Judd97Favorite Part

Judd97

Voted 10/10

One of my favorite parts of the trail. I wonder how long ago that chockstone fell down there?
Posted Feb 1, 2008 10:27 pm

Bob SihlerRe: Favorite Part

Bob Sihler

Hasn't voted

No idea, but what I wonder now is how long it will be until it falls the rest of the way!
Posted Feb 2, 2008 10:44 am

Buz GroshongGreenstone Dike

Buz Groshong

Voted 10/10

That feature is what is known as a greenstone dike. Greenstone is also called paleobasalt. The granite cracked and the molten rock flowed up through it and solidified too quickly for crystals to form. Greenstone probably weathers faster than the granite because it has undergone serpentinization, a chemical alteration that happens when it absorbs water. I first saw the chockstone in 1978, but I think I've seen pictures of it from the 30s - it will probably be there for quite some time.
Posted Jan 25, 2009 5:06 pm

Bob SihlerRe: Greenstone Dike

Bob Sihler

Hasn't voted

Thanks, Buz-- that beats the hell out of my explanation!

I disagree about the chockstone, though; it will probably be there until I hit the lottery, the day after which it will fall on me.
Posted Jan 28, 2009 9:31 pm

Buz GroshongRe: Greenstone Dike

Buz Groshong

Voted 10/10

I don't have to worry about that because I'll get run over by a bus the day BEFORE I win the lottery!
Posted Feb 13, 2009 12:12 pm

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Image Data
Bob SihlerSubmitted by Bob Sihler
on Jan 22, 2008 7:20 pm

Image ID: 374919
Hits: 7424 
Lat/Lon: 38.55170°N / 78.316°W
Object Title: Natural Staircase

Image Type(s): Informational, Scenery