CENTRAL ONTARIO 229 



thickness. On the shore opposite the mouth of the Otonabee river the 

 divide between Rice lake and lake Ontario lies less than 3 miles from 

 the lake and about 11 miles from lake Ontario, being over 900 feet above 

 the latter lake. On the north side of Rice lake, close to the lake, there 

 are extensive drift deposits, and, so far as the writer is aware, no bed- 

 rock is known. A little farther to the north, however, east of Peterboro, 

 bed-rock occurs at a higher level than the lake. This Rice lake valley 

 extends for a considerable distance southwest of the head of the lake as 

 a well marked depression. The general direction of the depression is 

 shown by the course of the stream, which enters the southwest end of 

 the lake at Bewdley. 



Tributary to Rice lake from the north is the Keene river, whose gen- 

 eral course is in accordance with the trend of the older valleys here 

 described. Whether it actually occupies one of these is uncertain. 

 Heading on the upland in the same region as the Keene — a flat, swampy 

 district of glacial deposits, including sand and gravel plains — is the 

 Indian river, which flows in almost exactly the opposite direction and 

 enters Stony lake near its eastern end, cascading down the front of the 

 Black River cuesta in a well marked obsequent valley. 



From the foot of Rice lake the river extends northeast in the same 

 valley, rock walled, steepest on the south, to a short distance below 

 Trent bridge, where the depression is less well defined. Here it widens 

 out a little and runs on top of the limestone for a short distance in an 

 irregular course, finally turning southeast and flowing in a succession of 

 rapids and falls through a new channel, the lower part being a gorge, 

 until it empties into the next old valley to the eastward. 



The upper portion of this valley is occupied by the Crow river. The 

 Crow river in its upper course runs along the front of the cuesta as a 

 subsequent stream, being the outlet for the waters from three lake3 — 

 Round, Belmont, and Marmora — located on the inner lowland, besides 

 a considerable amount of surplus drainage from the northeast. At 

 Marmora it enters a well defined narrow rock-scarped valley, trending 

 southwest, which gradually broadens. Below the junction with the 

 Trent from the northwest this valley is well defined and rather broadly 

 open as far as Campbellford. Below Campbellford the river leaves the 

 old valley, which is blocked by drift, and flows in a new channel. For 

 the first 2 miles below Campbellford it has not yet incised the rock to 

 any great extent. South of this as far as Meyersburg it runs in a shal- 

 low post-Glacial canyon, there being a heavy rapid and falls just below 

 Campbellford. Near Meyersburg it again turns east and widens out in 

 a broad, shallow depression upon the limestone. This depression 

 extends for a number of miles in either direction beyond the lowest 



