Drainage before tbe 1fce Bge, 241 



Miami, the Licking, the Scioto, the Big 

 Sandy, the Kanawha, the Hocking, and the 

 Great Beaver, besides numerous smaller 

 streams, have their own valleys that have been 

 worn away by the same process, and to a 

 greater depth than they now appear to be. 

 All of the material that once filled these val- 

 leys has been carried down by the water filling 

 up the bottom of the ocean and building out 

 the great delta of the lower Mississippi. 

 Mountains have been worn down and carried 

 away by the action of the running water until 

 their height is much lower than in former 

 times. The great lakes, that were enlarged 

 during the glacial period and in some cases 

 wholly created by the scooping out and dam- 

 ming up of the waterways and by piling gla- 

 cial drift around their shores have had some 

 of their outlets raised to a higher level, and 

 others have been created anew. 



The old river beds that formerly carrieH the 

 water that is now drained through the St. 

 Lawrence were eroded by the action of run- 

 ning water to a great depth, as is shown by 

 numerous borings along the valley of the Mo- 

 hawk and down the Hudson. The salt wells 

 at Syracuse, N". Y., have been put down 

 through glacial drifts and the salt water is 

 found in the bed of the old river. Great 

 bodies of salt are found at that low level, con- 

 stantly dissolved by the water percolating 



