2 - 



Surface 

 Crack 



t 



Primary 

 Ice Wedge 



10 



The Coastal Tundra at Barrow 



21 



J 



20 25m 



25 m 



FIGURE 1-10. Idealized ev- 

 olution of polygonal ground 

 from initial stage (top) to 

 low-centered polygon (mid- 

 dle) and finally high-cen- 

 tered polygon (bottom). 

 (Modified from Drew and 

 Tedrow 1962 and French 

 1976.) 



of polygon systems seen on the Biome research area: the large, low- 

 centered, rectangular type (orthogonal) polygons, many of whose centers 

 are permanently water-filled, and the smaller and presumably older non- 

 orthogonal type that shows a gradation of forms, including those with 

 highly elevated centers or tops, broad, flat centers, and low-centered 

 basins (Outcalt 1974). The more complex nonorthogonal polygons cover 

 over 75% of the Biome research area. 



The microrelief pattern superimposed on the regional topographic 

 and moisture gradients within the Biome research area creates diverse 

 edaphic and biotic conditions which are further illustrated in the follow- 

 ing sections. 



SOILS: DESCRIPTION AND DISTRIBUTION 



Despite the widespread development of polygonal ground most of 

 the soils in the Biome research area have formed on flat to very gently 

 sloping topography under cold, moist conditions that favor the accumu- 

 lation of organic matter. A high proportion of the soils have a tripartite 

 morphology: a histic or organic-rich surface horizon; a horizon of silty 

 clay to silt loam textured mineral material, commonly gleyed and with 

 variable amounts of included or enmixed organic materials; and an un- 

 derlying perennially frozen organic-rich horizon that is commonly coex- 

 tensive with the horizon above. The sequence of horizons has been inter- 

 preted as reflecting the burial of organic materials by lacustrine sedi- 



