GLACIAL LAKES — TAYLOR. 319 



the volume of Niagara River, indicates that the domination of the 

 outlet at Chicago endured for only a relatively short time, for the 

 Niagara River in the early part of the Port Huron stage of Lake 

 Algonquin made the widest section in the whole gorge. The time of 

 this lai^e-volume discharge at Chicago was the time when the Tole- 

 ston beach was made, and if there was a beach of Lake Chicago there 

 before and controlled by the same sill, it must have been overwhelmed 

 and worked over entirely by Lake Algonquin waters. From this 

 point of view Toleston is in reality only a local name for the Algon- 

 quin beach as developed in the southern part of the Lake Michigan 

 Basin. 



It was durmg the thu'd or Port Huron-Chicago stage of Lake 

 Algonqum that the larger part of the remarkable uplift of the Great 

 Lakes region occurred. It began when the Kirkfield outlet was 

 active, but soon raised KirMeld to a higher altitude than Port Huron 

 and Chicago, to which places the outflow was then shifted. The 

 uplift caused a remarkable northward splitting and divergence of 

 the beaches below the highest Algonquin beach. As a consequence 

 the beaches of this stage are many in number and show a large 

 vertical divergence northward. They seem to fall readily into three 

 groups, (a) the upper or main Algonquin group, (h) the Battlefield 

 group, and (c) the Fort Brady group. The main uplift began during 

 the second or Kirkfield stage, as pointed out above, but the much 

 greater part occurred during the third or Port Huron-Chicago stage, 

 and the most rapid movement was during the making of the Battle- 

 field gi'oup of beaches. At Sault Ste. Marie the vertical interval 

 between the highest Algonquin and the Nipissing beaches is 365 feet, 

 while in the area of horizontality the interval between these same 

 beaches is 10 or 12 feet. Coleman reports a beach at Lake Gondreau 

 (fig. 10) at 1,500 feet. This may be the highest Algonquian strand, 

 and is nearly 900 feet above that beach at Port Huron. 



For some distance north from the hinge line the upper Algonquin 

 beach rises gradually. It then begins to rise more rapidly and begins 

 also to si)lit into a vertically diverging scries of subsidiary strands 

 which are separated by wider and wider vertical intervals toward the 

 north. This splitting of the strands shows that the land was being 

 differentially elevated durmg the life of the lake. The different 

 strands are not of the same strength nor are they equally spaced 

 vertically, showing apparently that the uplifting movement was not 

 steady m its progress, but was irregular and was marked by a number 

 of pauses of more or less length. The idea held formerly that the 

 postglacial uplifts of the land in the Great Lakes region were gradual 

 and that they were evenly distributed through time is an error. The 

 uplifting movements were evidently quite spasmodic and relatively 



