THE PLEASURES OF SCIENCE 



strata of granite ten or fifteen feet below. The ver- 

 tical sides of the roads are like painted charts show- 

 ing all the gradations of the decaying rock-strata. 

 Five or six feet below the surface one can cut the 

 granite like cheese. From a brilliant terra-cotta it 

 fades out as you go down, and as the rock becomes 

 harder and harder, until the original gray of the 

 strata begins to appear, and bars and wedges are 

 required to remove it. Occasionally a vein of quartz 

 is exposed which shows no sign of decay. All North- 

 ern granite that I have seen is as hard at the surface 

 as anywhere beneath it, but Southern granite seems 

 to possess some inherent principle of decay. Yet 

 there are here scattered areas where the rock resists 

 decay and huge masses crop out and seem to shake 

 their gigantic fists in the face of Time. One such 

 mass which I twice visited and climbed is called 

 "Stone Mountain," not many miles east of Atlanta. 

 It is one of the most striking granite knobs in the 

 world. One sees it from afar rising above the sur- 

 rounding country, its light-gray surface mottled 

 with dark patches of pitch pine. Its base is six miles 

 around, and its summit nearly a thousand feet 

 above. Its shape suggests a huge pear, the stem end 

 being long and low, and the blossom end high and 

 abrupt. Standing on the high curve of this end, one 

 cannot see the base of the mountain beneath him, 

 and the cherry-pits which I dropped from my lunch 

 bounded down over the brim and fell to the ground 

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