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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Judd97 - Feb 1, 2008 10:27 pm - Voted 10/10

Favorite Part

One of my favorite parts of the trail. I wonder how long ago that chockstone fell down there?

Bob Sihler

Bob Sihler - Feb 2, 2008 10:44 am - Hasn't voted

Re: Favorite Part

No idea, but what I wonder now is how long it will be until it falls the rest of the way!

Buz Groshong

Buz Groshong - Jan 25, 2009 5:06 pm - Voted 10/10

Greenstone Dike

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.

Bob Sihler

Bob Sihler - Jan 28, 2009 9:31 pm - Hasn't voted

Re: Greenstone Dike

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.

Buz Groshong

Buz Groshong - Feb 13, 2009 12:12 pm - Voted 10/10

Re: Greenstone Dike

I don't have to worry about that because I'll get run over by a bus the day BEFORE I win the lottery!

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