1908.] PHYSICAL GEOGRAPHY MACKENZIE RIVER. 33 



Continuing northward, the Mackenzie is bordered on the west by a 

 broad expanse of mountain country, mainly unexplored. A few 

 low spurs of the same system cross the river and appear in the 

 form of isolated peaks or disconnected ranges to the eastward of its 

 valley. The principal western tributaries between latitude 62 and 

 G5° are the Red Rock and Gravel rivers. In the same interval the 

 Mackenzie receives several small streams which drain the country 

 east of the river. One of the largest of these is the Blackwater. 

 Mount Chirk, which is visible from the river at some distance below 

 the mouth of this stream, has an estimated altitude of 3.500 feet, and 

 is the highest of the mountains east of the Mackenzie. The most 

 conspicuous landmark in the immediate valley is Roche Trempe-l'eau, 

 a limestone mass which rises abruptly from the water's edge a short 

 distance north of latitude 63°. Bear River, the principal eastern 

 tributary of the Mackenzie, joins it just south of latitude 65°. As 

 the outlet of Great Bear Lake, it is described in its proper place (p. 

 44). Below its mouth, on the north side of the Mackenzie, is Bear 

 Rock. 1,4:00 feet in height. (See fig. 7. p. 105.) This mount is com- 

 posed mainly of Devonian limestone. 



Below here the Mackenzie resumes its general northwesterly course. 

 Wolverene Rock, 100 miles below Bear Rock, is formed, like that 

 eminence, by an uplift of the Devonian limestone, and is about 

 1,000 feet in height. Twenty-five miles below here a rocky ridge 

 crosses the river, forming the Sans Sault Rapid. The next important 

 feature in the valley of the Mackenzie is the defile called the ' Ram- 

 parts/ (See fig. 8, p. 106.) Here the river contracts from a width 

 of 2 miles to about 500 yard-, and flows for about 7 miles between 

 precipitous limestone (dill's, which in places rise to a height of 250 

 feet. 



Below Sans Sault Rapid the Mackenzie recedes from the moun- 

 tains, and they are not again visible until the delta is reached. Hare- 

 skin River enters the Mackenzie from the east a short distance north 

 of the Ramparts. Tt drains a large extent of rocky wooded country 

 between Great Bear Lake and die Mackenzie. For a long distance 

 below here the Mackenzie maintains a general northwesterly course. 

 A few fair-sized streams enter it from the east, but from the west 

 it receives no tributaries of importance. Tn about latitude 67° 10' 

 it turns rather abruptly at right angles, and for about 50 miles 

 follows a course considerably south of west. It is here bordered, 

 especially on the north, by high clay banks, through which several 

 good-sized streams cut their way. The river then turns northward 

 again and maintains a northwesterly direction to the delta. The 

 defile called the 'Narrows' or 'Lower Ramparts' is encountered 

 near (57° 40', and at its lower end Arctic Red River, from the south, 



44131— N<-. 27—08 3 



