93 



[Newberry. 



channel "of which there was no clue or even suggestion until working 

 up the origin of the Dundas valley." Prof. Spencer also does much more 

 than describe this buried channel in the paper referred to, for he there 

 discusses at length the origin of the lake basins, and reaches conclusions 

 which are in some respects at variance with those previously published by 

 myself. 



The points of difference between us are briefly these ; I had claimed the 

 existence of an ancient river flowing from Lake Superior through the lake 

 basin and down the Mohawk valley into the trough of the Hudson, and 

 thence to the ocean by New York. The valley of this stream, locally 

 expanded into boat-shaped basins by glacial action, according to my view, 

 formed the basins of the great lakes. 



Prof. Spencer denies that glaciers have played any part in the formation 

 of the lake basins, and more sweepingly that ice has any excavating power. 

 He also rejects the theory that the outlet of the lake basin was by the 

 Mohawk valley, saying, "the Mohawk course will not answer as the 

 Geological Survey of Pennsylvania has shown, for at Little Falls, 

 Herkimer Co., the Mohawk flows over metamorphic rocks." 



Meeting the last objection first, I venture to say that the Geological 

 Survey of Pennsylvania has not shown that the outlet of the lake basin 

 through the Mohawk valley "wont do." The fact that the present 

 Mohawk river flows over rocks at Little Falls is no new discovery, as it 

 could hardly escape the observation of any traveler over the New York 

 Central Railroad, but there is ample room in the adjacent country, where 

 heavy beds of drift cover the rock, for the continuation of the old, deeply- 

 cut Mohawk valley. In the country about Little Falls, not only is there 

 room for such a channel, but the facts necessitate its existence. The rocky 

 barriers over which the Niagara and St. Mary's flow are equally con- 

 clusive evidence against a continuous buried channel connecting the great 

 lakes, — in which we both believe. 



In regard to the agencj'' of glaciers in excavating the lake basins I think 

 no one who will carefully observe the facts, will hesitate to ascribe to 

 them an important function. It is true that Prof. Whitney denies that ice 

 has ever excavated a lake basin, and Prof Spencer echoes and endorses 

 the statement ; but it is also true that Prof. Ramsay, Director of the Geo- 

 logical Survey of England, claims that all lake basins have been excavated 

 by ice, and Prof. J. Le Conte whose range of observation has been extensive, 

 attributes the origin of Lake Tahoe and other lakes in the Sierra to this cause . 

 They have also supported their views of the power of ice as an erosive 

 agent, not simply by the authority of their names, but bj' an imposing 

 array of facts. In such circumstances those who deny any excavating 

 power to glaciers can hardly expect their curt dismissal of the ice theory 

 to be accepted without some sort of evidence beside their personal asser- 

 tion. It has happened to me to have opportunities of studying the eftect 

 of glaciers ancient and modern in many countries, and I am compelled to 

 say that the statements that ice has no erosive power, and has made no im- 



