202 PHYSICAL GEOGRAPHY. 



little below the transverse basin of the Lake of the Hills. 

 The channel of the Peace River is cut into silurian or 

 Devonian strata; but the Lake of the Hills, or Athabasca 

 Lake, runs eastward among the " intermediate primitive 

 rocks," and, as has been said above, receives a tributary- 

 stream from Wollaston Lake, situated near the water- 

 shed which divides the basin from Hudson's Bay. The 

 conjoined stream of the Peace and Athabasca Rivers as- 

 sumes the name of Slave River, which flows in the frac- 

 ture between the silurian and primitive rocks. The 

 junction of the western arm of the river with Great 

 Slave Lake marks the western border of the primitive 

 rocks, which is also indicated on the northern side of the 

 basin by the Fort Providence Inlet. Aylmer and Artillery 

 Lakes lie 1 50 feet higher at the east end of the lake, into 

 which they send their waters ; and in their immediate 

 vicinity, on the same plateau, are the sources of the Great 

 Fish or Back's river, which falls into the Arctic Sea, as 

 has been already stated. The streams that run from the 

 westward into Chesterfield Inlet must come from near the 

 same place ; and this inlet, from its transverse direction, 

 and east-north-east bearing from Great Slave Lake, has 

 an evident connection with that excavation, their axes 

 being nearly at right angles to the Rocky Mountain chain. 



In Great Slave Lake the Mackenzie is deflected from 

 the intermediate primitive belt, and flows first westwards 

 then northwards, in a channel scooped out of the upper 

 silurian strata and still newer deposits, for 1,000 statute 

 miles of river course, or nearly 600 geographical miles in a 

 direct line ; neither granite, gneiss, nor mica slate are seen 

 on its banks, and even trap rocks are rare, if any actually 

 occur. 



The River of the Mountains, embracing by its feeders 

 a more northern part of the Rocky Mountain chain, after 



