332 THE ICE AGE IN NORTH AMERICA, 



township, Lackawanna county, Pa.* The principal one is 

 from fourteen to seventeen feet in diameter at the top, and 

 is forty feet deep — the sides being very smooth. The de- 

 pression is worn through strata of sandstone, shale, and coal. 

 The pebbles which did the wearing were still in the bottom 

 of the hole when it was discovered, and are mostly of foreign 

 origin, though some of them consisted of pebbles cut from 

 the coal-bed itself. The elevation is eleven hundred and 

 twenty-nine feet above tide, and no explanation seems possible 

 except that which assumes that a stream of water was kept 

 running in that position for a limited period by ice-barriers. 



In passing, it is interesting to remark that the study of 

 the glacial deposits in the coal region becomes of great prac- 

 tical interest from the relation of their buried channels to 

 mining industries. Not only is there money to be saved by 

 knowing the depth of the till, and the inequalities of its 

 distribution, but the lives of the miners are seriously jeopard- 

 ized by ignorance upon this point. On December 18, 1885, 

 at Nanticoke, near the vicinity of the pot-hole just de- 

 scribed, one of the most shocking mining disasters on record 

 occurred, from miscalculating the course of a buried pre- 

 glacial channel, which was penetrated by the miners in an 

 unexpected place, causing a flood of quicksand, mud, and 

 bowlders to fill the mine and immolate twenty-six miners 

 beyond hope of rescue. 



Another instance of glacial drainage worthy of record is 

 reported by Professor J. E. Todd from the Missouri coteau 

 in Dakota. Crow Creek flows westward, and enters the Mis- 

 souri in Buffalo county, heading well in the terminal mo- 

 raine : f 



Two of its principal branches lead us into the heart of 

 the great interlobular moraines, the Rees, and the range of 

 which Turtle Point is the head, then by unmistakable channels 

 through them to the inner side of the moraine and out upon 



* " Annual Report of the Pennsylvania Geological Survey," 1885, pp. 

 615 620. f See map, p. 216. 



