1908.1 SEASONAL PHENOMENA MACKENZIE VALLEY. 41 



presses the beholder, who is likewise occupied in considering the pos- 

 sibility of the river being dammed sufficiently to overflow the ground 

 on which he stands. Such a catastrophe has destroyed more than one 

 post on the Mackenzie in years past. On this occasion the immense 

 volume of ice blocked the channel below the post and did not begin 

 to move in earnest until the night of May 2, when the jam broke 

 and the water, which had risen several feet, again fell. 



At this time a few ducks appeared in open places on the river. On 

 May G a small quantity of snow fell. The leaves of Ribes oxyacan- 

 thoides began to appear on May 8. By this time the river was nearly 

 clear of ice below 7 the mouth of the Liard, but above its month the 

 ice in the Mackenzie was still intact. On May 10 large sheets of 

 the Mackenzie ice broke away and floated down, but the river did not 

 open from above until May 13. The water then rose- and became filled 

 with ice, but on the following day was nearly clear again and had 

 fallen. On this date the leaves on aspens and birches were half an 

 inch in length. About the middle of May blue violets ( Viola albertina) 

 blossomed. The weather continued warm and vegetation advanced 

 steadily. On May IS Viburnum paucifiorum and Populus bal- 

 samifera put forth their leaves, and mountain cranberry (Vitis- 

 idcea) was in flower. Birds were now coming fast and additional 

 species w T ere noted daily, but on May 21 the weather turned cold and 

 stormy. This had the effect of retarding the advance of vegetation 

 and the tide of bird migration. On May 22 Ribes oxyacanthoides 

 and Calypso bulbosa were in flower. On May 23 a quantity of ice 

 from the Little Lake, or from Great Slave Lake itself, came down the 

 Mackenzie. The weather remained cold and stormy during the 

 remainder of the month and the conditions of vegetation and of bird 

 migration remained almost at a standstill. On May 2!) several inches 

 of snow fell. 



SEASONAL PHENOMENA ON MACKENZIE BELOW FORT SIMPSON. SUMMEB 1904. 



On June 1, 1901, I left Fort Simpson, and spent the remainder of 

 the month descending the Mackenzie. Though slops were made here 

 and there, my general rate of travel kept pace with the advance of 

 spring. The weather during the first few days of dune was favor- 

 able and vegetation made good progress. On June 2, a few miles 

 below Fort Simpson, the leaves of the tamaracks were just coming 

 out, and they were in the same condition at Fort Norman, 3 farther 

 north, on June 11. All along the river more or less ice -till lay on 

 the banks, but a few miles above Fort Norman the quantity was as- 

 tounding. Many of the Stranded cakes were upward of •_'<> feet in 

 thickness. They had evidently come from the mouth of some tribu- 

 tary which had frozen to the bottom, and whose waters, continually 

 overflowing and freezing, had Idled the valley with ice (see fig. '.)) . 



