33 
Table 8 continued. 
Distance 
Sample East or West Dust Content 
No. of road (m) (g cm’) x 104 
25 25 W 6 
24 25.5 9 
23 25 W 14 
22 255 21 
21 253 8 
20 25N 12 
19 25 W 245 
18 25E 149 
17 25 W 227 
16 BOE 76 
15 25 W 44 
14 25E 8 
1S 25 W 73 
12 25E 80 
11 W 54 
10 E 133 
9 25 W 10 
8 25E 100 
7 25 W 14 
6 255 78 
5 25 W 94 
4 25E 82 
g 40 W 10 
2 50 E 16 
by evaporation (sublimation) from the exposed 
soil and vegetation. The bare patches appear first 
on the south slopes of the dunes. Some of these 
were examined in detail during the afternoon of 
19 April 1973. The south faces of exposed dirt 
had 5-8 cm of dry powdery soil on top of hard 
frozen ground. The north sides of these same 
patches had less than 0.5 cm of dry powdery soil 
on top of the hard frozen soil. This indicates a 
significant difference in the amount of drying 
action produced by the sun and wind. The 
temperature 2 cm below the soil surface on the 
south side was -5.8 to -7.5°C; it was -11°C at 
the soil surface on the north side. The snow 
temperature was -16 to -17°C throughout its 
20 cm depth at nearby places; the time of day 
was 1610 and 1700. 
Electrical 
Ratio Conductance Ratio 
W/E umho cm"! W/E 
0.66 ae 0.75 
0.66 a 0.70 
0.66 SS 0.98 
0.64 He 1:36 
2.98 1.29 
5.50 S 1.26 
0.91 as 1.02 
0.40 — : 0.68 
0.10 = 0.58 
0.17 ne 0.53 
1.14 = 0.67 
0.62 at 1.61 
A typical example of a small sand hill is 
shown in Fig. 14. The view is toward the north. 
Note the hoarfrost crystals growing on the adja- 
cent snow surface; these are formed downwind 
of the exposed bare patches. The crystals grow 
partly because water vapor, which enters the air 
over the bare patch, condenses as it moves 
downwind in air that cools as it passes over the 
snow surface. The crystals were generally on the 
south sides of dunes and they began immediate- 
ly downwind of exposed bare patches of ground. 
A good example of this is shown in Fig. 15, 
which looks west from the dune area toward the 
road near traverse T-1. The frost crystals appear 
on the south side but not on the north side of 
the dune, and a bare patch of soil was immedi- 
ately upwind of the frost crystal area. The snow 
