GLACIAL LAKE ALGONQUIN. 413 



The surface of the country around Kirkfield is rather hilly, so that the approach to the 

 head of the outlet was somewhat broken by islands and the headward part was itself crooked 

 and very irregular. Several strong shingle beaches enter the head of the outlet, the upper- 

 most of which keeps considerable strength for a surprising distance down the outlet. Even 

 on Cameron Lake, which is much smaller than Balsam Lake, light gravelly beach ridges, not 

 strong but striking for such a situation, are well formed a mile southwest of Fenelon Falls. 

 The strength of the beaches and the erosion effects of the outlet river seem to indicate relatively 

 long activity for this outlet. There was only a few feet of gentle descent over the rock sill 

 at the head of this outlet, so it held the lake at a constant level. The lower fainter beaches 

 which lead into it were probably made in the three-outlet phase, when the discharge was leaving 

 Kirkfield and passing to Port Huron and Chicago. 



BEACH OF THE KIRKFIELD STAGE. 



With the passing of the transition stage, the level of Lake Algonquin became fixed by the 

 outlet at Kirkfield; and the erosion of the outlet below its head and the strength of the beaches 

 entering it and in its expanded parts give much reason to believe that the beaches of this stage 

 were strong on all the shores of Lake Algonquin. These strong beaches probably continued 

 northward to where they met the front of the ice, but as yet none of these meeting places of 

 beaches and moraines have been found. 



The large capacity of the outlet at Kirkfield makes it plain that tbe whole discharge passed 

 through it. Indeed, the dimensions of the old channel indicate a somewhat larger volume than 

 that of the present St. Clair River. The strength of the beach of the three-outlet phase seems to 

 show that the change was gradual or that there was a considerable pause while the three outlets 

 were active. 



In the early part of the uplift, until the discharge began to leave Kirkfield, the isobase of 

 Kirkfield was a nodal line on which the water plane swung as on a fulcrum, in effect falling at 

 the north and rising at the south. This line runs from Kirkfield west-northwest, passing about 20 

 miles south of Sault Ste. Marie. On all the shores south of this line tbe waters of the lake were 

 backed up and the beach previously made during the Kirkfield stage was submerged, and on aU 

 the shores north of this line the waters fell away and the beach previously made was abandoned. 



It follows that the beach of the Kirkfield stage was submerged everywhere in the southern 

 peninsula of Michigan and that, so far as this monograph is concerned, there are no beaches of 

 the Kirkfield stage to be described, the visible Algonquin beaches all belonging to the next later 

 stage. Outside of the area considered in this monograph there are beaches that belong to this 

 stage, but they are in Ontario and the States bordering on Lake Superior. For the sake of com- 

 parison, however, this beach at one or two localities will be briefly described in connection with 

 the beaches of the next stage. 



At Kirkfield the upper strand of the beach stands 883 feet above sea level, or 276 feet above 

 the Algonquin beach in the area of horizontality. But even this large uplift does not measure 

 the full elevation that affected Kirkfield, for before the movement began the beach at Kirkfield 

 marked a water plane that passed below the level of the Port Huron and Chicago outlets. At 

 least 40 or 50 and possibly 100 feet must be added to the 276 feet to get even the approxi- 

 mate uplift at Kirkfield. This, of course, affects also the tilt rate, for this must not be based on 

 the visible three-outlet beach which stretches from the hinge line at Grand Bend, Ontario, to 

 Kirkfield but on the submerged beach of the Kirkfield stage. 



PORT HURON-CHICAGO STAGE. 



HISTORY. 



The third or Port Huron-Chicago stage opened while the Kirkfield stage was closing; that 

 is to say, when the overflow commenced at Port Huron and Chicago it began to diminish at 

 Kirkfield, and the two stages overlapped for the time that the three outlets were active together. 

 It follows that, not counting the introductory transitional stage, the highest beach of Lake 



