Vol. 50.] MR. CHAS. DAVISON ON SNOWDRIFT DEPOSITS. 481 



to the wind it is packed and hardened, and until this happens 

 snow cannot be used for building, and sledging is difficult and 

 often impossible. " Fortunately for the architects," says Nares, 

 " the gales in the middle of September had formed hard snow- 

 banks, out of which a compact building-material was readily pro- 

 cured." " The snow, in spite of the low temperature," says Payer 

 (Oct. 25th, 1872), " lay in such masses between the small hummocks 

 and on the few level places that they [the sledges] sank deep into 

 it. It is storms of wind only that harden the snow, and for some 

 time we have had calms or light breezes." " Yesterday's storm," 

 remarks Greely (Jan. 17th, 1882), " has stripped every exposed 

 place of its usual snow, to pack it in dense, hard drifts, in the 

 hollows of the ground." ' So far as I am aware, no explanation has 

 been given of the action of the wind in hardening snow at a low 

 temperature ; but that it has such an effect is clear from numerous 

 observations, and from the importance attached to it by Arctic 

 travellers. 



4. Disappearance of Snow by Melting and Evaporation. 



During the Arctic winter snow and ice undergo but little decay, 

 for evaporation then takes place slowly, and it is not until late in 

 the spring that the sun can effectually melt the snow. The sun 

 alone has but little thawing power, until it has attained a consider- 

 able altitude. It is aided greatly, however, by the presence in the 

 snow of dust, sand, and minute plants, and when the dark earth or 

 rock below becomes partially uncovered, or when the snowdrift 

 deposit begins to appear on the surface, the rate of decay is materi- 

 ally hastened. Showers of rain, and dry warm winds of a fohn- 

 like nature, also assist largely in the disappearance of snow. 2 



Isolated stones and small patches of earth, owing to their power 

 of absorbing heat, sink some distance into snow ; kryokonite, as is 

 well known, is found at the bottom of holes in the Greenland ice. 

 But a thin and continuous coating of earth, like that which covers 

 many decaying snowdrifts, practically remains upon the surface, 

 though the finer particles may be washed down by rain and thaw- 

 water, to discolour the snow-granules below. So long as it remains 

 thin, this coating helps to melt the subjacent snow, and it increases 

 in thickness by the continual addition of particles to its under- 

 surface. But a limit may at last be reached, depending chiefly on 

 the depth to which the summer-heat penetrates the ground, when 

 the deposit on the surface becomes thick enough to prevent further 

 melting of the snow until a warmer climate supervenes. 



1 Greely, vol. i. pp. 183, 224 ; Hayes, pp. 217-18 ; Koldewey, pp. 376-77 ; 

 M'Clintock, pp. 207,391; Markham, p. 344; Nares, vol. i. pp. 177, 190-91, 

 222, 292 ; Payer, vol. i. pp. 178-79, 229, vol. ii. p. 39 ; Biohardson, vol. i. p. 349. 



2 Belcher, vol. i. p. 312 ; Hooker, vol. i. p. 252 ; Markham, pp. 380-83 ; 

 Nares, vol. i. pp. 40, 310-11, vol. ii. pp. 3, 6-7 ; Nordenskiold, vol. ii. pp. 33-35; 

 Parry A, pp. 165-66, 176; Parry B, p. 114; Payer, vol. ii. p. 252; tieebohiu, 

 p. 101. 



