NATURAL AREAS AND REGIONS 



129 



week, and on the 26th and 27th it became 

 still warmer and the ice practically 

 ceased running. On October 28, how- 

 ever, the weather became colder and the 

 ice again appeared. From this date it 

 continued to run and the snow steadily 

 accumulated. The thermometer did not 

 rise above the freezing point, and con- 

 sequently there was no thawing, except 

 to a very slight extent in sheltered 

 spots directly exposed to the sun. While 

 the river remained open its expanse of 

 ice-laden water added greatly to the 

 intensity of the cold. From the same 

 cause the trees and shrubs were nightly 

 loaded with ice crystals. On the night 

 of November 7 the minimum tempera- 

 ture recorded was 10, and on the 

 night of November 15 a temperature of 

 27 was registered. 



During the night of November 18 the 

 river finally set fast. In this process 

 the drifting ice accumulates until it 

 has so filled the river that it jams in 

 some place where it has partially bridged 

 the channel. Against this barrier the 

 oncoming floes, laden with saturated 

 snow, are pushed by the current, and 

 becoming lodged in all possible positions 

 are almost instantly cemented together 

 by the intense cold. This process con- 

 tinues upstream, usually without inter- 

 ruption, until the whole river is closed. 



During November and December the 

 cold steadily increased in intensity and 

 the snow gradually accumulated. When 

 no thaw occurs the snow remains so 

 light and powdery that it does not settle 

 appreciably. On the shortest days the 

 sun rose in the southeast about 9.30 

 a.m. and, after describing a low arc 

 over the tree tops, set about 2.30 p.m. 

 Even at midday its heat was scarcely 

 appreciable. After the middle of De- 

 cember the thermometer scarcely ever 

 rose above zero. From January 1 to 

 March 12, 1904, it rose above zero on 

 only eight occasions. The lowest tem- 

 perature recorded was 54, on January 

 20 and 21. During the third week in 

 January the average daily maximum 

 was 30; the average daily minimum 

 -45. 



A grave which was dug on February 

 26, 1904, afforded an opportunity to 

 ascertain the depth to which frost had 

 penetrated. The location was a sandy 

 knoll somewhat sheltered on the north 

 by a thick growth of young trees and 

 open to the south. Snow lay to a depth 

 of about 3 ft. The frost had reached a 

 depth of only 20 in., but the excavation 

 was not carried to a sufficient depth to 

 reach the permanently frozen sub- 

 stratum. 



On March 26 the temperature first 

 rose above the freezing point and from 

 that date did not descend below zero. 

 When the spring thaw set in the snow 

 had attained a depth of nearly 4 ft. 



The progress of the season at Fort 

 Simpson from March to June, 1904, as 

 indicated by the temperatures of suc- 

 cessive weeks, is shown in the following 

 table: 



Temperatures of successive weeks, spring 



of 1904, at Fort Simpson, 



Mackenzie River 



*The "fourth week" includes the last nine or 

 ten days of the month. 



On March 19 a flock of white-winged 

 crossbills, evidently migrants, was seen. 

 On March 28 the first hawk owl of the 

 spring was observed, and snow fleas 

 (Achorutes) appeared. About the same 

 time several species of small birds, 

 which had been seen rarely during the 

 winter, appeared in larger numbers. 

 On March 30 the buds and catkins on 

 the willows and alders imparted a 

 brown tinge to the hillsides where these 

 shrubs were common . On the same date 

 snow buntings, which had been absent 

 since the middle of December, reap- 



