FIELD AND STUDY 



many hundred feet below. The rock apparently does 

 riot undergo any chemical change as has the rock 

 of the surrounding country in which it is rooted, but 

 it disintegrates much more rapidly than Northern 

 granite and has imparted a light-gray hue to the red 

 lands that spread out from its base. Huge slabs 

 weather off its surface and their degradation affords 

 enough soil here and there to give sustenance to low 

 growths of pitch pine. The rock as a whole must 

 have shrunk enormously even in our geologic age, 

 probably many times its present size; yet it remains 

 one of the most notable outcroppings of the orig- 

 inal granite in this country. 



Why granite rock is so soft and ungranite-like 

 in the southern countries is to ihe a puzzle — the 

 result, perhaps, of some circumstance of its original 

 cooling. In southern California, at Riverside, tour- 

 ists climb or motor to a bold granite peak called 

 Rubidoux. The sides and the summit of the moun- 

 tain are strewn with huge rounded granite boulders. 

 I chanced to overhear a tourist explaining to a 

 friend that these detached boulders were brought 

 there and dropped by the old ice-sheet that covered 

 the northern part of the continent ages ago. But he 

 was giving his friend a bit of misinformation. The 

 old ice-sheet did not extend so far south, and these 

 plump, smooth boulders had simply weathered out 

 of the underlying granite, and had never left the 

 land of their birth. They were a titanic brood 

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