302 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1912. 



GLACIAL LAKES OF THE HURON-ERIE BASIN. 



The lowland which stretches from Lake Huron southward to Lake 

 Erie was abandoned by the ice sheet in the middle stages of the devel- 

 opment of the glacial lakes, but continued to be covered by the lake 

 waters, so that the waters in the southern part of the Lake Huron 

 basin were joined with those in the basin of Lake Erie as one, and at a 

 later stage this extensive lake v/as further expanded so as to cover the 

 western and southwestern parts of the basin of Lake Ontario. 



The succession of lakes in this basin is more complex than in any 

 other part of the lake region. These complexities grew out of sev- 

 eral different causes: (1) The configuration of the chief elements of 

 relief, relatively deep basms separating the higher lands, and the posi- 

 tion and varying altitude of the watershed south of the lakes; (2) 

 the general direction of the glacial retreat and the trend of the ice 

 front with reference to these features; (3) the stadial oscillations of 

 the ice sheet during retreat, comprising not only periodic movements 

 of retreat and halt, but also alternating movements of readvance over 

 relatively wide intervals of space; and (4) (especially in the later 

 stages) the tilting or northward differential elevation of the land. 

 The stadial readvances introduced the greatest element of complexity 

 and produced their effects chiefly by closing outlets and raising the 

 level of the waters. This occurred repeatedly after the waters had 

 been lowered not long before b}^ a movement of retreat. 



South of a line passing about 5 miles north of Birmingham, Mich., 

 and through Ashtabula, Ohio, the old beaches of the Huron-Erie 

 basin are all horizontal; north of it they rise gradually toward the 

 north-northeast. The area south of this "hinge" line is known as 

 the area of liorizontaMty. The succession of lake levels within this area 

 is shown m the table below. The order of occurrence on the slope 

 is shown by their altitude in feet above sea level, begmning with the 

 hio-hest: their order in time is shown by the numbers on the left. 

 The beaches that were submerged and modified by a rise of the lake 

 level due to a readvance of the ice are put in italics. 



1 . First or highest Maumee, 790 feet. 



3. Middle or main Maumee, 780 feet. 

 2. Lowest Maumee, 780 feet. 



5. Whittlesey, 735 feet. 



4. Arkona, 710-694 feet. 



7. Warren (Forest), 680 feet. 



6. ^Yayne, 660 feet. 



8. Grassmere, 640 feet. 



9. Lundv (Dana, Elkton), 620 feet 



