102 LAKES OF NORTH AMERICA. 



passed away, — all of these links in the complex history have not been 

 completely worked ont, and this attractive field is still open to the geolo- 

 gist and geographer. 



In conclusion, it is but fair to state that while the history of the 

 Laurentian basin outlined above will, I believe, be accepted as in the 

 main correct by most geologists of the United States, whose attention has 

 been directed to the subject, it is widely at variance with the conclusions 

 of at least two Canadian geologists. Sir J. William Dawson maintains, if I 

 understand his hypothesis correctly, that the sea, laden with icebergs, invaded 

 the Laurentian basin in Pleistocene times, and that the moraines and other 

 deposits occurring in it and over a wide extent of adjacent country, and 

 believed by most observers to be of glacial origin, are shore accumulations, 

 and that icebergs and floe-ice played an important part in their formation. 



The ancient beaches about the Laurentian lakes, while considered as 

 true shore lines by Spencer, are thought by him to have been formed at 

 sea-level during a time of continental submergence, and that the ocean 

 had free access to the basin. 



It may be that in these summary statements I do injustice to the 

 views of the gentlemen referred to, but the conclusions indicated are so 

 widely at variance with a vast body of consistent evidence gathered by a 

 score or more of skilled observers, and is so directly opposed to my own 

 observations, l)oth of living glaciers and of the records of past glaciation, 

 that the}' do not seem at present to l)e open to profitable discussion. 



A subsidence of the eastern border of the continent during the later 

 stages of the Glacial epoch, or following its close, throughout a belt 

 widening from New York city northward, and including the valley of 

 Lake Champlain, is well known. When the studies leading to this con- 

 clusion are extended to the basins of the Laurentian lakes, however, not 

 only is there an aljsence of salt-water shells and other evidences of marine 

 occupation, but, seemingly, positive evidence of lacustral condition. 



The region to the north of Lake Superior has not been sufficiently 

 studied to admit of an opinion being reached in reference to the questions 

 just considered, from the records there obtained. It may be found that 

 the highest shore-line in the Superior basin was formed by a water body 

 in direct communication with the sea to the north, as suggested by 

 Taylor. Should this hypothesis be sustained, it would add an interesting 

 chapter to the history of the Superior basin, and render a review desirable 

 of the evidence of a similar nature in the eastern portion of the region 

 now drained by the St. Lawrence. 



