NIPISSING GREAT LAKES. 



461 



at Nipigon, as indicated by the production of its plane from other places where it is better 

 identified on tins shore, is 8 or 10 feet lower than would be expected and lacks distinctive 

 character. It is therefore rejected here, though given a probable place of identification in 

 the review of Lawson's paper. Peninsula Harbor lies about 13 miles north of the isobase of 

 North Bay, and the extreme reach of the lake waters northeastward from that line is 14 to 15 

 miles. The isobase runs about N. 65° W. to S. 65° E., and the tilt line or line of greatest rise 

 therefore runs about N. 25° E. 



POST-NIPISSING UPLIFTS OF NORTHERN LANDS. 



From the northward rise of the Nipissing beach it appears that uplift of the northern lands 

 did not cease with Lake Algonquin, but continued, though perhaps with less rapidity, for some 

 time after the beginning of the Nipissing Great Lakes. It affected the lands bordering Lake 



Figure 9. — Map of the isobases of the Nipissing: Great Lakes at the two-outlet stage. The numbers above the isobases are altitudes above the 

 horizontal or unaffected part of the beach south of the hinge line; the numbers in parentheses below the isobases are altitudes above sea level. 



Superior, the northern third of Lake Michigan, and all of Georgian Bay and Lake Huron 

 except Saginaw Bay and the south hah of the south arm of Lake Huron. (See fig. 9.) 



Goldthwait's measurements on the two sides of Lake Michigan seem to show that the 

 hinge of the uplift that deformed the Nipissing beach is there on the same line as that which 

 deformed the Algonquin beach. In the basin of Lake Huron this relation has not yet been so 

 clearly made out and some doubt remains as to whether the hinge line of the Nipissing beach is 

 not a few miles farther north than the Algonquin. In a small area at the west end of Lake 

 Superior the plane of the Nipissing beach appears to pass below the level of the lake. In the 

 basins of Lakes Michigan and Huron the Nipissing or two-outlet beach comes to an attitude of 

 horizontality at about 596 feet above sea level. This level in the basin of Lake Superior is 

 4 or 5 feet below the water surface. Agreeing with this interpretation, Mr. Leverett found that the 



