242 a. W. g. Wilson — Trent river system 



those north of the lake have been developed on the bed-rock, and these 

 still preserve all the essential features of valleys produced by river erosion. 



The so-called outlet channel of the Saint Lawrence river is in reality 

 a complex of three partly submerged valleys similar to the bay of Quinte. 

 The portion of the Saint Lawrence in the vicinity of the Thousand 

 islands is merely a series of longitudinal basins with connecting straits 

 across sags in the interbasin ridges. No definite channel exists. The 

 topography is similar to that characteristic of partly submerged Lauren- 

 tian areas found in many places over the great Laurentian peneplain. 



The courses of the rock valleys associated with the Saint Lawrence 

 outlet and of the rock valleys of New York to the south of the river 

 may be traced for a considerable distance on the bed of lake Ontario by 

 means of the soundings. 



The water of the Saint Lawrence system passes eastward at the pres- 

 ent time over the lowest part of the Frontenac axis. The existence of 

 the sag over which the river passes is probably due to local differential 

 depression. The direction of flow of the water west of the submerged 

 divide on the axis is opposite to that in which the water flowed when 

 the valleys were carved in the limestone area. East of the divide on the 

 axis the direction of flow is probably as it was in pre-Glacial times. 



At a time prior to the existence of lake Ontario the valleys forming 

 the Saint Lawrence outlet, all the valleys of that part of New York east 

 of lake Ontario, the valleys of the Ba}^ of Quinte section of the Trent 

 system, and the valle} 7 s of Prince Edward count} 7 formed part of a river 

 system now dismembered. 



Finally, it may be suggested that the maturity of form, the size, and 

 the course toward the deepest part of lake Ontario suggest that the 

 pre-Glacial Black river was the master stream of the system. Its course 

 and position with reference to the Niagara cuesta suggest that it was a 

 master subsequent stream flowing in front of the cuesta westward. 

 Probably some of the streams in the valleys forming the lakes on the 

 upper part of the Trent system were tributary to this master subsequent 

 stream either directly or in a few cases after confluence with each other. 



As has been pointed out by Grabau* and the writer f independently, 

 this master subsequent was probably joined by a second master subse- 

 quent from the north, flowing south in front of the Niagara cuesta, the 

 two subsequents being confluent in the vicinity of the depression whose * 

 submerged portion forms Burlington bay, at Hamilton, Ontario ; thence 

 they probably followed the course of an initial consequent stream 

 through the Niagara cuesta via the Dundas valley to the Erie lowland. 



*A. W. Grabau: Guide to the Geology and Paleontology of Niagara Falls and Vicinity. N. Y. 

 State Museum Bulletin, xlv, 1901. 

 f Physical Geology of Central Ontario. Trans. Can. Inst., vol. vii, 1901, p. 181. 



