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



on the adjacent Archean areas are probably associated with an extensive 

 system of faults of pre-Orodovician date * 



Notes on other Streams Tributary to Lake Ontario from the East 



In all essential features the valleys of the southwest-flowing streams 

 in New York state are similar to those in Ontario. To the south and 

 west of Clayton, and southeast as far as Black river, there are large rela- 

 tively flat areas, the intervalley uplands, with a very limited drift cover 

 and frequent exposures of flat limestone rock. A number of small creeks 

 head on the different parts of this upland and flow southwest, the valleys 

 gradually becoming well defined as they grow wider and deeper. The 

 partly submerged western portions of these valleys form the numerous 

 inlets on the eastern shore of lake Ontario. Without a single exception, 

 the islands off that coast are merely partly unsubmerged portions of the 

 rock wall between two valleys. The valley of Three-mile creek extends 

 for some distance above the head of the present stream, and is well de- 

 fined by a low rock scarp on either side, the valley lying below the level 

 of the upland plain. The writer did not have the opportunity of ascer- 

 taining whether it extended completely across the limestone area. 



The Chaumont river occupies a valley of the first type of those described 

 above, although the present river does not come from the inner lowland. 

 The head of the present stream lies in a flat limestone plain between 

 bounding rock scarps. A couple of miles farther east another stream 

 heads in the same valley and flows northeast. The lower portion of the 

 valley is submerged to form Chaumont bay. A reference to the map 

 (plate 8) would suggest that the former courses of the valley of Three- 

 mile creek and Chaumont river were between point Peninsula and the 

 mainland. In the field, however, it is found that it is extremely improb- 

 able that this was so, because rock exposures are found close together 

 at or near water-level, even on the neck between the peninsula and the 

 mainland. The earlier course of one of the streams may have been 

 across this neck, because there is a well defined valley here, but the 

 course of the pre-Glacial Chaumont river seems to have been to the 

 south of the point Peninsula. Three Mile creek at one time probabty 

 flowed between the peninsula and the mainland, but at a later stage it ap- 

 pears to have joined the Chaumont river, possibly a case of local stream 

 capture, the bottom of the valley of the creek, now submerged as Three- 

 mile bay, being at a considerably lower level than the bottom of the 

 sag in the rock surface at the neck of the Peninsula. The valleys of the 

 smaller streams marked by Guffin bay were tributary to Chaumont 



* This also has beeu suggested to the writer by Doctor Gilbert. It is proposed to discuss the 

 problem in a later paper on the origin of roches montonne. 



