84 
11. T. FERRAR. 
from a dear sky ; on the surface of the Ross Piedmont, they supplied much of 
the superficial ice of the area. In the course of a day or two the crystal-plates 
break up into grains, which drift hither and thither with the wind. After a 
blizzard, soft snow usually becomes tightly packed, and the snow-dunes which have 
been formed show a smooth and hard surface. Later this dune-snow granulates, 
notwithstanding that the temperature remains constantly below 0° F. If a wind 
springs up, the grains are carried away and the dunes disappear. Graduated pegs 
were set up in the snow to determine the changes which take place in its sur- 
face, and the observations show that during two years much snow drifted past 
them. Wind carries the snow bodily away ; the importance of this factor in 
reducing the height of the inland-ice of South Victoria Land will be appreciated if 
we recall the six and a half days during which the sledge-parties were weather- 
bound on the edge of the 
inland - ice. During that 
week, the air, which passed 
at an average rate of 50 
miles an hour, was so 
charged with fine snow that 
objects 10 yards away were 
indistinguishable. That this 
is not unusual may be in- 
ferred from the fact that at 
Winter Quarters the days 
on which no silting, or 
surface-drift, of the snow 
took place were few. 
The winds by carrying 
snow on to the surface of 
sea-ice help to drain the 
land ; and the sea-ice, as it breaks up and floats north, takes away much superfluous 
water-substance which has had no opportunity of glaciating the land (Fig. 49). 
The snow-dunes usually took the form of crescents and symmetrical elongated 
domes, never more than three feet high. The longer axes of the domes were parallel 
to the direction of the prevailing winds, those of the crescents transverse. As soon 
as their substance becomes granular, the winds remove and obliterate all trace of them. 
During the process of destruction, snow-surfaces resemble a wind-worn surface 
of false-bedded and slightly indurated sand. The less granulated layers are the 
more indurated, and stand out beyond the coarser and less resisting bands, thus 
giving the appearance of stratification. The forms assumed by the disintegrating 
dunes are very variable,* and some become very fantastic. The silting snow helps 
* Vaughan Cornish, Geog. Journ., August 1902, vol. xx, p. 137. 
Fig. 48. — Undulating scepace of hard “ Marbled ” Snow. 
