16 Spencer — Deformation of Algonquin Beach, 



western portion of the beach, at the head of the bay, is about 

 3 feet per mile, in a direction of N". 20° E., with an eastern 

 equivalent of about one foot per mile. The uplift increases 

 so that east of Georgian Bay the mean rise is 4*1 feet per 

 mile in a direction of N. 25° E., with the eastern equivalent 

 of l'T feet per mile. 



At Grand Bend, the beach rests upon a fine stony drift 

 clay — the latest deposit of till in that region — which is charged 

 with numerous scratched stones. It is also indistinctly strat- 

 ified. The same holds true at Wilson's and other places. 

 About Georgian Bay, it also rests upon the upper till. In 

 short, the waves, which formed the beach, have commonly 

 removed the silt deposits that covered the floor of the lake, 

 during the earlier episodes of the higher beaches, and cut into 

 the underlying drift deposits during the Algonquin episode, 

 before the beach structure was laid down. In many places, 

 especially about Georgian Bay, the boulder-pavements are well 

 developed, especially between the different ridges of the 

 Algonquin Beach, for it is often broken up into a series of 

 prominent ridgelets, the lowest being, where developed, as 

 much as 28 feet below the upper. 



There are several beaches about Georgian Bay, at lower 

 altitudes than the Algonquin, but these rise less rapidly 

 toward the northeast than the greater named beach. At 

 Clarksburg, there is a beach at 81 feet above the lake, and 

 terraces at 62 and 45 feet, besides a numerous series of beaches 

 extending from 28 feet down to the water level. Near Wye- 

 bridge, the more conspicuous terraces are at about 183, 73, 55 

 and 11 feet above the lake ; and there are numerous fainter 

 shore-lines. These all show that the time of the subsiding of 

 the waters was marked by numerous pauses. 



Between Kirkville and Balsam Lake, there is a depression 

 a few feet below the level of the upper part of the Algonquin 

 Beach. But of this later. 



No animal life has been found in the beach itself. But in a 

 terrace, adjacent to the Saugeen River (bridge east of South- 

 ampton), where there is an embayment of the Algonquin 

 Beach, there is a bed of fresh-water shells, discovered by 

 Mr. Spillman. This is at an altitude of 90 feet above the lake, 

 or over 40 below the beach. This deposit may have been on 

 the floor of the lake during the Algonquin episode, or it may 

 belong to a lower water-level. The river has now cut down 

 its bed far below this level. At the head of Georgian Bay, 

 fresh water shells have been found up to 78 feet.* 



There are several depressions across the Laurentian Moun- 

 tains, between Lake Huron and Hudson Bay which do not 



* Geology of Canada, 1863. 



