1908.] SEASONAL PHENOMENA MAOKRNZIH VALLEY. 41 



presses the beholder, who is likewise occupied in coiisideriiio- the jk)S- 

 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 innnense 

 volume of ice blocked the channel beloAv 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 6 a small quantity of snow fell. The leaves of Rihes oxyacan- 

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

 clear of ice below the mouth of the Liard, but above its mouth 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 ( V iola albevtina) 

 blossomed.-^ The weather continued warm and vegetation advanced 

 steadily. On May 18 Viburnum jyaucifloriim and Popnlvs hal- 

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

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

 species were 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 Eihes oxyacanthoides 

 and Calypso hidhosa 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 29 several inches 

 of snow fell. 



SEASONAL PHENOMENA ON MACKENZIE BELOW FORT SIAIPSON, SUMMER 1904. 



On June 1, 1904, I left Fort Simpson, and spent the remainder of 

 the month descending the Mackenzie. Though stops were made here 

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

 spring. The Aveather during the first fcAV days of June Avas fa Ador- 

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

 beloAv Fort Simpson, the leaA^es of the tamaracks Avere just coming- 

 out, and they were in the same condition at Fort ^sTorman, 3° farther 

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

 the banks, but a fcAv miles above Fort Norman the quantity Avas as- 

 tounding. Many of the stranded cakes Avere upward of 20 feet in 

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

 tary Avhich had frozen to the bottom, and whose Avaters, continually 

 oA^erfloAving and freezing, had filled the A^alley AA'ith ice (see fig. 3). 



