36 



NOETH AMEKICAN FAUNA. 



[NO. 27. 



immense pressure behind it breaks its wa}^ seaward, occasionally 

 becoming dammed and raising the level of the water until the in- 

 creased pressure again clears a channel. At Fort Simpson, near lati- 

 tude 62°, the ice continues to drift in quantity for some days after its 

 disruption. About ten days, on the average, after the Mackenzie 

 opens at this point, or about the time that the breaking ice has reached 

 latitude 65°, the upper Mackenzie opens and the channel is filled 

 again with floating ice. Sometimes a third consignment of floes, 

 from the ' Little Lake ' or from Great Slave Lake, fills its current. 



The following table shows the dates of the opening and closing of 

 the Mackenzie at Fort Simpson during a series of j^ears: 



Table showing coiidition of Mackenzie at Fort k^iiiipsoii. 



Year. 



Mackenzie opened — 



First 

 drift ice. 



River 

 closed. 



Year. 



Maclfenzie opened— 



First 

 drift ice. 



River 

 closed. 



At mouth 

 of Liard. 



Above 

 mouth of 

 Liard. 



At mouth 

 of Liard. 



Above 

 mouth of 

 Liard. 



1876 



May 14 

 May 8 

 ___-do__. 

 May 3 

 May 7 

 May ]3 

 May 7 

 May •! 





Nov. 4 

 Nov. 1 

 Oct. 16 

 Nov. 12 

 Nov. 2 

 Oct. 12 

 Nov. 1 

 Oct. 28 



Nov. 17 

 Nov. 28 

 Nov. 26 

 Nov. 20 

 Nov. 26 

 Nov. 18 

 Nov. 30 

 Nov. 20 



1884 



May 12 

 May 2 

 May 3 



May 14 

 May 7 

 May 27 



Oct. 11 

 Oct. 28 

 Oct. 30 

 "Oct. 14 

 Nov. 10 



Nov. 18 

 Nov. 20 

 Nov. 25 

 Nov. 18 



1877 



1878 



1879 



May 19 

 May 17 

 May 19 



-—do 



_-_-do .__ 

 May 20 

 May 5 



1885 

 1886 

 1903 



1880 



1904 



Apr. 29 



May 5 

 May 3 



May 13 

 May 11 

 May 10 



1881 



1905 



(') 

 Nov. 25 

 do 



1882 



1906 



in 

 Oof. 



1883 - . 



1907 











1 



" From tlie Liard. The ice from the Mackenzie above the Liard began to run Oct. 18. 

 ''Had not closed on Nov. 24. 

 '■Had not begun to drift Nov. 1. 



The following table shows the dates of occurrence of certain phe- 

 nomena at Fort Norman, distant from Fort Simpson about 180 miles 

 by the river. Some of the years being represented in the Fort 

 Simpson table also, the rates of progress of the opening and closing 

 of the river may be noted : 



Tahle shoioing condition of Mackenzie and date of first snow at Fort Norman, 



Mackenzie. 



Year. 



River 

 opened. 



First 

 snow. 



First 

 ice. 



River 

 closed. 



Year. 



River 

 opened. 



First 

 snow. 



First 

 ice. 



River 

 closed. 



1872 . 





Sept. 28 

 -_-do.._ 

 Oct. 15 



Oct. 7 

 Oct. 21 

 Nov. 2 

 Oct. 23 

 —do 



Nov. 8 

 Nov. 12 

 Nov. 18 

 Nov. 9 

 do_- 



1881 





Oct. 2 

 Oct. 9 



do___ 



Oct. 7 

 Oct. 14 

 Oct. 24 



Nov. 12 

 Nov. 14 

 Nov. 10 



1874 



May 17 

 May 25 

 May 24 

 May 19 

 May 12 



1882 



1883 



May 14 

 May 11 

 May 28 



1875 . 



1884 



1876 



Oct. 10 

 Sept. 25 

 Sept. 28 

 Oct. 3 

 Oct. 7 











1877 . 



Oct. 18 

 Oct. 22 

 Oct. 20 

 Oct. 22 





1886 





Oct. 18 

 Oct. 5 



Nov. 13 

 Nov. 8 



1878 



Nov. 7 

 Nov. 2 

 Nov. 12 



1887- 



May 24 

 May 19 

 May 21 



Sept. 23 



1879. _— 



May 9 

 May 22 



1888 



1880 



1904 — 



















In the autumn of 1903 the ice in Peel River at Fort McPherson 

 commenced to drift on October 4, and the river set fast on October 12. 

 In the following spring it opened on May 23. The lowest tempera- 

 ture registered there during the same winter was — 60°. 



