DEFORMATION OF SHORE LINES. 



505 



to hinge on the same line as the Algonquin, but this is probably not the case at the west end 

 of Lake Superior. The isobases of the Algonquin and Nipissing beaches are shown more 

 completely in figure S (p. 439) and figure 9 (p. 461). 



The beach observed by Coleman at Gondreau Lake north of the east end of Lake Superior 

 has an altitude of about 1,500 feet. A conjectural isobase is drawn from this place to a point 



Figuke 15.— Map showing northward shifting of the hinge lines. 



north of Buda, 40 miles northwest of Port Arthur, where in 1895 the writer observed a well- 

 defined upper limit to extensive lake sediments. 



Besides the extreme border line of the Wisconsin ice, four later positions of the ice front, 

 corresponding closely to critical times in the uplift, are shown in figure 14. The first position, 

 "WW, is that of the main moraine of the Port Huron system, and marks the position of the barrier 



