Yol. 50.] MR. CHAS. DAVISON ON SNOWDRIFT DEPOSITS. 475 



2. Snowdrift Deposits in the Arctic Regions. 



In the Arctic regions the conditions are exceptionally favourable for 

 the formation of deposits from snowdrift. The deposits are hardly 

 likelv, however, to attract the close attention of travellers, though 

 incidentally the conditions are somewhat fully described in their 

 narratives. One reason, no doubt, for the absence of notices is that, 

 however thick the deposits may be, everything below the first foot 

 or so is perpetually frozen and beyond the range of casual observa- 

 tion. But, just as in this country the last surviving patches of 

 snowdrift are always more or less discoloured, so Arctic travellers 

 sometimes refer to the black and dirty snow to be found in spring 

 at the foot of cliffs. According to M'Clure, decaying ice and snow 

 are of a dingy yellowish hue. Parry remarks that a fall of fresh 

 snow in the summer months gives a more wintry aspect to the 

 scenery than the unmelted snow of the preceding winter. This, he 

 says, is " always easily known by its dingy colour, and its admixture 

 with the soil." The last observation is an important one, and it 

 also explains how snowdrift deposits may be overlooked. The sur- 

 face of snow- and ice-fields is occasionally darkened by dust, 

 evidently wind-drifted, and dirt-layers are seen in the interior when 

 the edges of tilted floes are exposed or when excavations are made 

 in the snow. 1 



The most direct evidence on this point is that given by the late 

 Dr. J. Eae, who spent several winters in the north of Canada. " In 

 all parts of Arctic America where I have been," he says, " a fall of 

 snow is usually either accompanied or followed by a gale of wind 

 more or less strong, chiefly from one direction, with thick snowdrift, 

 which cuts away earth and sand in minute particles from the wind- 

 ward side of any hill or rising ground in its course, and these 

 particles are carried along until they find a resting-place under the 

 lee of some steep bank or cliff. These foreign substances, when 

 mixed with a great depth of snow, are not readily seen, but when 

 the spring evaporation and thaws remove a great part of the snow, 

 a stratum — more or less thin — of coloured matter, is visible on the 

 surface." 2 It will be seen from the next section that several of the 

 conditions under which snowdrift deposits are formed are clearly 

 described in this passage. 



IV. Formation of Snowdrift Deposits. 



1. Formation of Snowdrifts. 



Snow falls in the form of flakes only when the temperature is 

 not far from the freezing-point. In high latitudes, especially in 

 winter, flakes are unknown, and the snow consists of fine, hard 



1 (The index to the abbreviated references in tbis and the following footnotes 

 will be found on pp. 472-473.)— Greely, vol. i. pp. 312, 398-99, vol. ii. pp. 30-31 ; 

 Koldewev. p. 120; M'Clintoek, p. 146 ; M'Clure, pp. 193, 229; Nares, vol. i. 

 pp. 149, 168-69, vol. ii. pp. 12. 59, 61 ; 'Nature,' vol. xxvii. (March 22ud, 1883) 

 p. 496, vol. xxix. (Dec. 6th, 1883) p. 135 ; Nordenskiold, vol. i. p. 178; Parry C, 

 pp. 23. 104, 155. 



2 " Major Greely on Ice," 'Nature,' vol. xxxiii. (Jan. 14th, 1886) pp. 244-45. 



