350 MODIFICATION OF GREAT LAKES BY EARTH MOVEMENT. 



much smaller than the modern lake, because the basin was then com- 

 paratively low at the northeast. Its outline is approximately shown 

 by the inner dotted line of the accompanying map. Instead of reaching 

 from the site of Buffalo to the site of Toledo, it extended only to a 



Fig. 1. 



ANCIENT AND MODERN OUTLINES OF LAKE ERIE. 



The broken lines show the positions of the shores at two epochs of the lake's history. 



point opposite the present city of Erie, and it was but one-sixth as 

 large as the modern lake. Since that time the land has gradually risen 

 at the north, canting the basin toward the south, and the lake has 

 gradually encroached upon the lowlands of its valley. At a date to 



Toronto 



Fig. 2. 



ANCIENT AND MODERN OUTLINES OF LAKE ONTARIO. 



The broken line shows the original extent of the lake. 



be presently mentioned as the Nipissing, the western end of the lake 

 was opposite the site of Cleveland, as indicated by another dotted 

 line. 



The next great lake to be released from the domination of the ice 

 was probably Ontario, though the order of precedence is here not 



