26 



pied by the Trent chain of lakes and rivers, the beach has 

 an altitude of 883 feet (269.2 m.) and 15 miles (24.2 km.) 

 farther north rises to 925 feet (282.0 m.). Northward 

 from the latter point, on account of the rough and com- 

 paratively little drift-covered surface of the country, the 

 beach is difficult to follow and although a strong beach, 

 supposed to represent the Algonquin, has been found at 

 a number of points as far northward as the town of North 

 Bay, sufficient data have not been collected to enable 

 definite correlations to be made. 



The maximum tilt rate of the beach in the Lake 

 Simcoe district is in a direction N. 21° E., and 

 the rate increases from 2.3 feet (.7 m.) per mile in the 

 southern portion to nearly 6 feet (1.8 m.) in the northern 

 portion. Lakes Simcoe and Couchiching, and a number 

 of smaller lakes to the east, occupy shallow basins which 

 rarely exceed 100 fee; (30.5 m.) in depth, and evidently 

 owe their present existence as lakes to the upward tilting 

 of the land towards the north. Were the land depressed 

 to the relative altitude which it had when the Algonquin 

 beach was made the present outlet of Lake Couchiching, 

 for example, would be about 175 feet (53.3 m.) lower. 



North and east of Lake Simcoe, the drift is relatively 

 thin, but in the district to the west and southwest of the 

 lake the drift becomes much thicker, and no exposures of 

 solid rocks are known to occur. Well borings made in 

 this district show the drift deposits to have a thickness 

 of at least 375 feet (114. 3 m.), and as the drift hills rise 

 to an altitude of 200 to 300 feet (61 to 91 m.) above the 

 valleys in which the borings were made it is possible that 

 the drift has in places a much greater thickness. 



Numerous sections in the drift show two till sheets 

 separated by stratified sands and gravels. The uppermost 

 or last till sheet consists of two distinct portions, an upper 

 part, often with a well bedded character and composed 

 of a loose sandy till, and a lower portion consisting of a 

 more compact, sandy clay till with little or no trace of 

 stratification. Associated with the former and generally 

 crowning the summits of hills and ridges are well stratified 

 deposits of sands and gravels, which often bear a semblance 

 to beach ridges. Their mode of origin is not clear, but 

 they do not appear to be referable to wave built features. 



Over a considerable part of the district the till of the 

 lower portion of the last till sheet merely forms a thin 



