STREAMS TRIBUTARY TO LAKE ONTARIO 237 



valley. From the soundings in this part of the lake, it is inferred that 

 the ancient Chaumont valley was tributary to the ancient Black River 

 valle} 7 which lies to the south of Stony island. 



The next stream to the south is Perch creek. This stream rises near 

 the Archean areas to the northwest of Theresa at Hyde lake. Under 

 the local name of Hyde creek it flows across the Potsdam lowland in a 

 well denned rock-scarped valley to Perch lake. This latter lake is 

 located in a reentrant in the limestone cuesta. From Perch lake it flows 

 southwest through the cuesta to Black River bay. About a mile below 

 the village of Limerick, the present stream passes underground and fol- 

 lows a subterranean channel for nearly a mile. The older valley on top 

 of the limestone is well denned, and judging from the bare character of 

 the valley floor and the distribution of debris, at times of flood the 

 present stream occasionally flows overground. At Limerick the present 

 channel is a slightly sinuous rock gorge, about 50 feet in width and 20 

 in depth. In places the sides are locally rounded, though most of the 

 gorge is clifFed. The general features of the gorge sides are such as to 

 suggest that it is pre- Glacial, and that its form has been slightly modi- 

 fied by the ice. It is quite possible that the portion near Limerick is of 

 glacial origin, owing to the down fracturing of the roof of the subter- 

 ranean channel under the weight of superincumbent ice. 



The largest and most important of the streams which cross the lime- 

 stone areas to enter the eastern end of lake Ontario is Black river. The 

 larger part of the catchment basin of this stream lies in the Adirondacks. 

 The main stream flows along the inner lowland in front of the Paleozoic 

 cuesta for many miles above Carthage, receiving a kw short obsequent 

 tributaries which run down the cuesta front. About 7 miles north of 

 Carthage it turns abruptly and flows southwest toward Watertown. 

 At Watertown the course changes a little to the north of west* and fol- 

 lows this direction to Black River bay. This bay is merely a partly 

 submerged portion of the river valley. The course of the valley can 

 readily be followed by the soundings to the southwest of Stony point, 

 lying between the point and Stony island. The modern stream in its 

 course across the limestone areas has cut out a rocky gorge in the bot- 

 tom of the older flat-bottomed valley, and this gorge forms the present 

 channel of the river. At Black river the gorge has a depth of about 40 

 feet. To the south of the old valley the walls are steep and often clifFed. 

 To the east of Watertown and about a mile and a half from Black river 

 is a very remarkable steep-sided rock valley called Rutland hollow, cut 

 as it were on the side of the old Black River valley, since the upland to 



*A pre-Glacial modification not yet fully investigated, but evidently closely associated with the 

 joint structure. ■ 



