642 



ALFRED IV. G. WILSON 



The valley of the Betsiamites, described by Low (20, p. 7), 

 and the well-known gorge of the Saguenay are two of the most 

 striking of these deep valleys which traverse the St. Lawrence 

 swell. 



The drainage of the central portion of the peneplain south of 

 James Bay presents somewhat similar features. Barlow draws 

 attention to the fact that 



Probably one of the most interesting of the physical features presented by 

 the district is the valley occupied by Lake Temiscaming and the Ottawa 

 River. The greater portion of this valley is a very steep rocky gorge, 

 fringed on either side by lofty hills or perpendicular cliffs which rise abruptly 



Fig. 13. — Post-glacial gorge of the Hamilton River, immediately below the 

 Grand Falls. The vertical cliff on the left has a height of 500-' 



{Photograph by A. P. Low, i8g4.) 



to a height of from four hundred to six hundred feet above the surface of 

 the water, while the average of a large number of soundings indicate that 

 the lake has a mean depth of over four hundred feet. The depression, 

 therefore, occupied by these waters would be about one thousand feet below 

 the level of the surrounding country, and as the bottom of the lake, wherever 

 examined, consisted in the deeper portions of a very fine gray unctuous clay 

 or silt, this depth may have been much greater before the accumulation of 

 this material. From Mattawa to the mouth of the Montreal River these 

 abrupt and rocky shore-lines prevail, but above the mouth of this stream the 

 lake undergoes considerable expansion and the shores exhibit a more gradual 

 slope towards the surface of the water. The traveler ascending the Ottawa 

 River is thus usually impressed with the mountainous character of the district, 

 but an ascent of the hills on either side at once shows that the adjoining 

 country is comparatively level, and that what appeared as a range of hills 

 are in reality the inclosing walls of this great valley. (4, p. 23.) 



He also states that "the Mattawa and Montreal Rivers, in a 

 lesser degree the Sturgeon and Temagami Rivers, occupy rather 

 deep and important depressions in this rocky plateau." 



