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From: lindsay@K.GP.CS.CMU.EDU (Donald Lindsay)
Newsgroups: sci.misc
Subject: Re: Holes in Granite
Message-ID: <171@PT.CS.CMU.EDU>
Date: Wed, 14-Oct-87 09:40:26 EDT
Article-I.D.: PT.171
Posted: Wed Oct 14 09:40:26 1987
Date-Received: Fri, 16-Oct-87 00:04:46 EDT
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Organization: Carnegie-Mellon University, CS/RI
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Keywords: granite, lightning, mountain

Lightning shouldn't be able to make a 3" deep hole in hardrock.

One possibility is inclusions in the rock: that is, pieces of a softer rock
became embedded in the magma which cooled to become the granite.  The
inclusions (that are on the surface) have since weathered.

Another possibility is that magma contracts when it cools. This can lead to
interesting forms - tunnels and "giant's stairs" - and might lead to shallow
holes, I suppose.

Since you found many holes, I incline to the inclusion theory.

-- 
	Don		lindsay@k.gp.cs.cmu.edu    CMU Computer Science