Soil thaw 
In 1972 Bilgin (1975) measured the progres- 
sion of soil thaw at 14 different sites. Soils 
varied in texture, organic content, moisture, 
slope and resulting vegetative cover. The range in 
maximum soil thaw by late August was between 
25 cm in wet organic soil and 90 cm in the dry 
sandy upland soils. Fig. 3 contains plots of thaw 
progression in four distinct soil conditions. This 
range in soil thaw over relatively small distances 
is common for northern Alaska and has been 
reported for a detailed transect in the Barrow 
area (Brown 1969). 
Soil Temperature 
Soil temperatures as influenced by polygon 
microrelief were recorded at six locations at 3-hr 
intervals during summer 1972. The sites were 
located within a 15-m radius with duplicate sites 
selected in a polygon trough, on a polygon rim, 
and in a polygon center. Fig. 4 is an idealized 
cross-section and plan view of the site. 
Fig. 5 contains the daily mean values for 
each of the three microrelief positions at 1, 5, 
and 10 cm depths and the Prudhoe air tempera- 
ture record. 
The July and August 1972 mean daily tem- 
peratures in the upper 1 to 10cm soil were 
Sandy Upland 
Tundra 
80 
(cm) 
Sandy Dry 
Meadow Tundra 
(op) 
{e) 
Silty Dry 
Meadow Tundra 
40 
Dry Phase 
Organic Soil 
Depth of Thaw 
20 
20 10 20 
Aug (Sire 
Fig. 3. Seasonal progression of thaw for four 
Prudhoe Bay soils (Bilgin 1975). 
Table 6 
Comparison of 1971 precipitation data (mm) 
June 
(13-30 June) July August September 
Barrow trace 24.9 8.9 4.3 
Barter Island 2.0 76:5) 1027, 23.1 
Prudhoe Bay 
(near Pingo Site) 2:5 20.3 16.5 6.9 
Happy Valley 5uilie 50.8 20.1 = 
“Value wholly or partially estimated. 
Fig. 4. /dealized cross-section and plan view of 
polygon microrelief for soil temperature 
measurements. 
within the range of 2° to 12.5°C. The maximum 
daily mean temperatures at 10 cm were below 
8°C. The extremes in mean daily temperatures 
were encountered in the polygon trough with 
core 3 being the coolest (2° to 6.5°C) and core 
6 the warmest (3.5° to 12.5°C). These differ- 
ences are undoubtedly due to local microrelief 
and soil properties. Temperatures at these shal- 
low soil depths closely reflected daily air tem- 
peratures. 
Since gravel pads and roads cover a signifi- 
cant portion of the Prudhoe landscape, it is 
important to know how they influence near- 
surface temperature and thaw regimes. Tempera- 
tures of gravel surfaces as compared to air 
