THE FRIENDLY ROCKS 



measures. The Catskill plateau was lifted up before 

 Carboniferous times began, so that there is no coal 

 in this region. We should have to look overhead for 

 it instead of underfoot. When the Catskill plateau 

 rose above the waters, Pennsylvania and most of 

 the continent to the west was under the sea, receiv- 

 ing additional deposits, thousands of feet thick in 

 many places, and in due time supporting a vegeta- 

 tion that gave us our vast deposits of coal. 



The geologic tornado that brought this hailstorm 

 of quartz pebbles, so marked in the conglomerate 

 that caps the highest Catskills, seems to have been 

 a general storm over a large part of the northern 

 hemisphere, as this conglomerate underlies the coal 

 measures, both in this country and in Europe. It 

 must have occurred in late Devonian or early Car- 

 boniferous times. On the top of Lookout Mountain, 

 in Tennessee, I gathered a handful of pebbles that 

 had weathered out of the Carboniferous sandstone 

 that the ages have exposed on the summit. 



An earlier storm of quartz pebbles occurred in 

 Silurian times, which formed the Oneida conglom- 

 erate in central New York, and the Shawangunk 

 range in southern New York. This latter range is a 

 vast windrow made up of small pebbles varying in 

 size from peas to large beans, cemented together by 

 quartz sand. It is several hundred feet thick and 

 runs southwest through Pennsylvania into Virginia, 

 affording another proof of the abundance of quartz 



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