From:
Norman Watts <Norman_Watts@zzzzzzz>
Date:
Mon, 19 Dec 2005 07:00:21 -0500
Subject:
planes in granite
On Dec 16, 2005, at 4:18 PM, John Vancamp wrote:
Quoted text begins.Gilbert (1904) noted that sheet structure in the domes of the Sierra
Nevada tends to parallel all topographic surfaces and that the
separation of sheets penetrated to depths between 50 and 100 ft
perpendicular to the surface. At this rock-fall release the thickness of
the most exfoliation sheets visible on the cliff surface, probably
ranges only from 3 to 6 ft thick.
End of quote.
So even those thick layers are exfoliation sheets. I guess its all
relative. What looks "thick" to me is nothing compared to the mass of
the granite whose upper surface is exposed and called the Sierra
Nevada.
Quoted text begins.The same search also brought up a link to a great picture of Enchanted
Rock-- the exfoliation dome I am familiar with.
End of quote.
I have to go see Enchanted Rock. My climbing partner for more than than
a decade is from Texas and has talked often about Enchanted Rock. I
think it enchanted him.
Norman Watts, Ph. D.
National Institutes of Health
50 South Drive, Rm. 1509
Bethesda, MD 20892-8025
Phone: (301) 402-3418
Fax: (301) 480-7629
- References
- message 00500: planes in granite - John Vancamp (16 Dec 2005)
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