1908.] 



LIFE ZONES. 



49 



Weekly summaries of temperatures, June to September, 1900, between Artillery 

 Lake and Chesterfield Inlet. 



Mean daily maxima 



June 



July 



August 



September 



Mean daily minima: 



June 



July 



August 



September 



° Artillery Lake. 



'' Kasba Lake to Hanbury River. 



Hanbury River. 



'' Thelon River. 



c Theion River to Aberdeen Lake. 



t Sehultz Lake to mouth Chesterfleld Inlet. 



" Chesterlield Inlet. 



'' Lower Thelon to Aberdeen Lake. 



' Thelon River. 



) Thelon and Hanbury rivers. 



* Hanbury River to Artillery Lake. 



The monthly means were as follows: June, 52.29; July, 55.51; 

 August, 48.96. 



Owing to the great thickness of their icy covering, some of the lakes 

 of the Barren Grounds are not clear of ice in backward seasons until 

 July, or even August, when new ice has usually begun to form in 

 still water. They generally break up in late June or early July. The 

 rivers, having the advantage of a current, open earlier than the lakes. 



During a residence of about five years at Fort Anderson, on Ander- 

 son River, MacFarlane observed the river to set fast on two occasions 

 as early as September 10, though once it remained open until October 

 10. In 1857 the Anderson broke up at the mouth of the Loekhart on 

 June 12. At Fort Anderson the dates of the opening of the river 

 were as follows: 1861, about May 15; 1862, May 19; 1863, May 30; 

 L864, May 31; 1865, June 2. During the last days of June, 1864, 

 MacFarlane found nearly all the lakes on the Barren Grounds still 

 covered with ice, though the rivers were open. 



In 1821, when Franklin's party started to descend the Coppermine 

 on July 1, the lakes on its upper course were still covered with ice. 

 Apparently the river had opened only a short time before. In 1849 

 Doctor Rae noted the breaking up of the same river near its mouth 

 on June 28. At this time the leaves of the dwarf birches were out, 

 and the leaf buds of the willows had begun to develop. The lower 

 part of the river remained blocked with ice until July 13. 



LIFE ZONES OF THE ATHABASKA-MACKENZIE REGION. 



The area treated of lies within the 'Boreal Region and comprises 

 parts of each of its three subdivisions — the Arctic, Hudsonian, and 

 Canadian zones. The boundaries of these belts are shown on Plate II 

 in as much detail as is possible with our present knowledge. 



44131— No. 27— 08- 



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