218 A. W. G. WILSON — TRENT RIVER SYSTEM 



upper reaches, mere flat shallow depressions on the limestones. As we 

 descend any one of them we find that it gradually deepens ; usually its 

 southeast side soon becomes marked by a low cuesta-like escarpment, 

 with a steep slope toward the valley and a gentle slope away from the 

 crest. The northwest side is less steep than the other, but is steeper 

 than the normal outer slope of the minor cuesta which forms the south- 

 east side of the next adjacent valley northwestward. The valley has 

 been formed by an incision of the rocks, and the difference in slope of 

 the two sides is due to the relation existing between the direction of the 

 valley and the dip of the rocks. These valle} T s slope, as do those of the 

 first type, in a direction a little to the south of the strike of the rocks, 

 but not in the direction of the dip. There are some special cases which 

 will be referred to in the more detailed discussion of the Trent River 

 system in* a subsequent section. 



It very frequently happens that valleys of the first type are continuous 

 with longitudinal valleys developed on the Archean areas, and the head- 

 valley lake often occupies a basin part of which is underlain by Archean 

 rocks. The depth of the upper part of these valleys is in part con- 

 trolled by the relatively harder Archean rock, the latter often being 

 exposed in the bottom of a valley some miles away from the cuesta front, 

 while the valley walls are of limestone. 



SPECIAL DESCRIPTIONS 



Trent river proper. — The most important stream in the region is the 

 Trent river. What is usually considered as the main stream of the river 

 system heads in a small lake in the Laurentian region of central Hali- 

 burton county. This stream, known as the Gull river, flows southwest 

 in a valley bounded by Archean rocks to Mud Turtle lake, a partly 

 flooded valley of the first type, noted above. Between here and Balsam 

 lake the stream continues in this valley. Balsam lake is a broad shal- 

 low depression, located on the Black River cuesta, in which the river 

 expands. Between Balsam lake and lake Ontario the stream follows a 

 very remarkable zig-zag course, alternately occupying an old more or 

 less drift-blocked rock-bound valley, usually of the first type here de- 

 scribed, and flowing in a new channel across one of the intervalley areas. 

 In these old valleys it usually expands to form lakes. Following down 

 stream from Balsam lake, these lakes are named respectively Cameron, 

 Sturgeon, Pigeon, Buckhorn, Love Sick, Deer, Stony, Clear, Katche- 

 wanaka, and Rice. Scugog lake and Chemong lake also belong to the 

 system, though they are not on the direct line of the main stream. Be- 

 tween these various lakes, excepting the last two, Katchewanaka and 

 Rice, the stretches of running water are very short and are not usually 



