LATE PLEISTOCENE BEACHES IN ONTARIO. 259 



the low divide of the Au Train and Whitefish rivers, the latter of which is 

 tributary to Little bay de Noc. The series of beaches observed north of 

 Lake Superior at a locality near the Petits Ecrits, between Nipigon bay 

 and the Slate islands, at heights in descending order 331, 267, 259, 224, 90, 

 40, and 30 feet above the lake,^ are apparently referable, for the highest, to 

 a time when Lake Superior was confluent with the adjacent great lakes, with 

 outlet by Chicago to the Illinois river, and, for the lower levels, to later 

 stages of separate existence of Lake Superior, with discharge by a river, 

 probably at first crossing the Au Train water-shed, but afterward, during 

 the formation of the three beaches at and below 90 feet, outflowing by the 

 present mouth at the Sault Ste. Marie. Like the beaches of Lake Agassiz, 

 this series seems to indicate that the departure of the ice was followed by a 

 northward uplift of the land. 



Beaches of sand and gravel occur on Owen Sound, at the southwestern side 

 of Georgian bay, about 200, 150, and 120 feet above Lake Huron, or about 

 780, 730, and 700 feet above the sea.f These probably belong to a stage of 

 the glacial retreat when a vast confluent glacial lake, which Spencer has 

 named Lake Warren, stretched from the western end of the basin of Lake 

 Ontario over the whole or the greater part of the four higher Laurentian 

 lakes. During the glacial retreat from Lake Michigan and the western 

 portion of Lake Erie, each of these areas had an outlet to the Mississippi ; 

 that of Lake Michigan crossing the height of land close west of Chicago^ 

 only twelve or fifteen feet above the lake and approximately 595 feet above 

 the sea, while the outflow from Lake Erie passed over the lowest point of 

 the water-shed between the Maumee and the Wabash, 770 feet above the 

 present sea level. The departure of the ice from the southern peninsula of 

 Michigan, however, gave to the glacial Lake Erie, with its extension north- 

 ward over Lake St. Clair and the southern end of Lake Huron, a lower outlet 

 across the water-shed of the Shiawassee and Grand rivers, allowing the gla- 

 cial lake Erie-Huron to flow into the glacial Lake Michigan by a pass which 

 is now 729 feet above the sea. Soon after this, and apparently previous to 

 the dates of the Owen Sound beaches, Lake Erie-Huron was further lowered 

 by the recession of the ice from the Strait of Mackinaw ; and the fully ex- 

 tended Lake Warren, probably holding one level through connecting straits 

 from lakes Ontario and Erie to Lake Superior, discharged its surplus waters 

 by the Chicago outlet. If the correlations here indicated are true, the dif- 

 ferential uplift of portions of the shores of Lake Warren, toward the north, 

 northeast, and east-northeast, above its Chicago outlet, has been approxi- 

 mately 338 feet near the middle of the north side of Lake Superior, 185 feet 

 on Owen Sound, and about 265 feet near the eastern end of Lake Erie, where 



* Geological Survey of Canada, Report of Progress to 1863, p 913. 

 t Ibid., p. 912. 



XXXIX— Bull. Geol. Soc. Am., Vol. 2, 1890. 



