In summary, the stratigraphy of snow on the 
Arctic Slope can generally be described by refer- 
ring to only four major varieties of snow. In 
approximate order from top to bottom in the 
snow pack these are: 
Range of Range of 
Grain size density 
Snow type (mm) (g cm-3)* 
= 
. Fresh new snow, variable 0.5 to 1.0 0.15 to 0.20 
crystal forms sometimes <0.5 
2. Wind slab, hard, fine- 0.5 to 1.0 0.35 to 0.45 
grained 
3. Medium-grained snow 1to2 0.23 to 0.35 
4. Depth hoar, coarse 5 to 10 0.20 to 0.30 
loosely-bonded crystals 
Spring thaw 
Some case examples of the snow structure 
measured during the spring near the Tundra 
Biome pingo site at Prudhoe Bay (Figs. 1 and 5) 
will be discussed. Figs. 6a and 6b shows the 
pingo, with the automatic recording weather 
station on top of it, during fall and spring. The 
photograph of early fall snow structure shown in 
Fig. 2 was taken at the time and place when the 
photograph in Fig. 6a was taken (6 September 
1971). 
A typical example of the snow structure on 
the tundra during spring, prior to melting (Table 
1), is shown in Fig. 7; this profile was measured 
350 m NE of P-2 (Fig. 5) on 14 April 1972 (Fig. 
7). Three layers were easily distinguished by 
brushing the side of the pit to reveal differences 
in resistance to abrasion. They show up clearly 
in the photograph and in the density and strati- 
graphy data which are plotted below it; they 
may be briefly summarized as follows: 
1. Top—fine-grained (0.5-1.0 mm), wind pack- 
ed, density = 0.36 gcm°?. 
2. Middle—medium-grained (1-2 mm), density 
= 0.26 gcm*. 
3. Bottom—coarse-grained, depth hoar crystals 
(5-10 mm), density = 0.19 gcm’s. 
The total water equivalent of the snowpack 
in this example was 12.5 cm H>O as determined 
by integrating the depth-density profile; the 
amount of heat required to raise its temperature 
17 
Fig. 6a. Pingo, 6 September 1977. 
Fig. 6b. Pingo, 14 April 1972. 
“The density ranges are only approximate and indicate the differences one may expect 
between these snow types. 
