184 Transactions of the Canadian Institute. [Vol. VII. 



sided and flat-bottomed. In almost all of these the river breaks into 

 rapids, and occasionally plunges over a low fall (Plate VIII). In parts of 

 the lower course of the Trent there are two rock terraces, one a small 

 rock-cut bench, the other due to the removal of the drift debris from the 

 old rock surface. There is reason to think that in parts of the course 

 there are remnants of yet higher terraces upon the drift, but they are 

 not conspicuous topographic features (Plate III, fig. 2, p. 171). 



The relations of all of these terraces to the Pleistocene lake levels 

 and to the former water supply are interesting problems which have not 

 been considered. The present valleys are inappropriate in size and 

 form to the present streams in flood. 



Parts of the present valleys of these streams and their tributaries, 

 and the valleys of all streams east of the Moira, are rock- valleys, not of 

 recent origin, and have already been described under the caption 

 " Eastern Rock-Valleys." 



Along Lake Ontario the waves have cut benches and sea clifls in the 

 drift deposits. The longshore action is distributing the material, thus 

 derived, east and west from the vicinity of Whitby, forming bars, spits 

 and hooks. Towards the west the most important of these are Toronto 

 Island and Burlington Beach. Towards the east, from Presqu' Isle 

 neck to Point Peter, there are a great many bars blocking the ends of 

 partly submerged rock valleys, and forming large and small lakes. 

 Back from some of these bars, small sand-dune belts have formed. 



