No. 4.] CLAYPOLE — PRE-GLACIAL GEOGRAPHY. 189 



drained by a river system which flowed at a much lower level 

 than at present. At that time our chain of Lakes — Huron 

 Erie, and Ontario — apparently formed portions of the valley of a 

 river which subsequently became the St. Lawrence, but which 

 then flowed between the Adirondacks and the Appalachians in 

 the line of the deeply buried channel of the Mohawk, passing 

 through the trough of the Hudson. . . . Lake Michigan was 

 apparently then a part of a river course which drained Lake 

 Superior and emptied itself into the Mississippi." 



It is somewhat aiflicult to reconcile this with the next para- 

 graph, which is as follows : 



" With the approach of the cold period, local glaciers formed 

 on the Laurentian mountains, and as they increased in size gradu- 

 ally crept down, and began to excavate the plateau which bor- 

 dered them on the west and south. The excavation of our lake 

 basins was begun and perhaps in large part effected in this 

 epoch. The extent of the erosion produced in the epoch under 

 consideration will be best appreciated by one who will stand on 

 the cut edges of the great series of rocks exposed on the southern 

 slopes of Lake Erie and Lake Ontario, and in imagination fill 

 the vast vacuity which separates him from the base of the Lau- 

 rentian hills." 



On a previous page (72) we read the following : 



" All our great lakes are probably very ancient," and "their 

 formation may have begun during the coal measure epoch." 



And on p. 74 : 



" There can be no doubt that the basin of each of the great 

 lakes has been produced by a local glacier. . . Our lake basins 

 must have been formed before or after the continental glacier, 

 or both before and after." 



And once more we find in the volume for 1873, p. 172, when 

 speaking of the buried river channels, of which mention will be 

 made presently, Dr. Newberry says : 



" They were formed at a time when Lake Erie did not exist 

 as a lake but was represented by a river flowing through some 

 portion of the basin it occupies, and receiving the Cuyahoga, 

 Rocky River, the Chagrin, Grand River, &c, as tributaries, at 

 a level 200 feet below the present mouths of these streams. 

 This was anterior to the first epoch of the drift period." 



The view expressed in the last extract appears to be the only 

 one now tenable, and the object of this paper is to support and 

 to extend it to other parts of the region of the great lakes. 



