GLACIAL LAKE ALGONQUIN. 



437 



possibly two seem to belong to the Fort Brady. Farther south the vertical interval 

 between the lower member of the upper Algonquin grotip above and the Nipissing below is so 

 narrowed that in the absence of strong individual characteristics it is impossible to distinguish 

 with certainty between the Battlefield and Fort Brady groups. Both groups are crowded 

 into narrower space and are represented by fewer ridges than farther north. 



Beaches having moderate strength and now recognized as belonging in all probability to 

 the Fort Brady group were seen by the writer a number of years ago near Rogers and farther 

 south. In Gregory's summary of his leveling operations beaches that probably belong to 

 the Fort Brady group were observed as far south as Alpena, but their identification is not yet 

 certain. 



In Ontario the Fort Brady group of beaches is fairly well developed at some localities, 

 especially along the north side of the Penetang Peninsula, but they are generally not strong. 

 They were found also at some places along the south side of Georgian Bay, but are not so well 

 displayed there as farther north. 



At North Bay, Ontario, where some of the beaches are well developed a mile north of 

 the town on a terrace overlooking the head of the North Bay outlet channel, the upper and 

 lower limits of the group have not been definitely determined, although the lower limit appears 

 to be at a beach about 50 feet above the Nipissing. At this place four beaches, including the 

 lowest and covering a vertical interval of 31 feet, appear to belong to the Fort Brady group. 

 In all probability there are higher ones and perhaps lower ones, although several fairly favor- 

 able localities near North Bay did not appear to show them. 



Mr. Leverett reports this group of beaches from several places on the northern peninsula. 

 In 1S93 the writer found them faintly developed at several places on the south side of Lake 

 Superior, and subsequently Mr. Leverett found them at other localities. The writer visited several 

 of Lawson's north-shore localities in 1895 and at most of them saw light beaches above the 

 Nipissing which it now seems evident belong to the Fort Brady group. 



ALTITUDE. 



In the Fort Brady group of beaches no single beach has strength or individual character- 

 istics that make it possible to distinguish it from other members at different localities, and 

 it is not possible to trace the variations of the group in altitude with accuracy. The altitudes 

 given below, compared with the altitude of the Nipissing beach at the same places, show the 

 general relations. 



Altitudes of the Fort Brady beaches. 



At the south end of Mackinac Island a faint gravel ridge which rises only 5 feet above the 

 Nipissing beach a few yards away may be merely a storm ridge of the Nipissing. Aside from 

 this, both the upper and the lower members, where the latter are not cut away, appear to be 

 somewhat higher in the north than in the south, but it is perhaps an open question whether 

 some of the Fort Brady beaches may not pass southward under the Nipissing beach. South of 

 Charlevoix and Alpena there are in many places one to three beaches between the Nipissing 

 and what seems clearly to be the lowest ridge of the upper Algonquin group, but it has not been 



