26 



J. E. Hobbie 



FIGURE 2-1. Aerial view looking north across the U.S. Tundra Biome 

 research area. The ice-covered Arctic Ocean is in the background. The 

 Naval Arctic Research Laboratory camp complex is in the upper right 

 corner. The ice-covered water body is Middle Salt Lagoon. Polygonal 

 terrain is visible in the foreground and the study ponds in the lower left 

 corner. (Photograph by CRREL.) 



Geomorphology 



The Arctic Coastal Plain consists of unconsolidated silty sand and 

 gravel of Quaternary age (Gubik Formation) deposited in a shallow sea 

 (Black 1964). The uppermost section at Barrow was deposited and 

 reworked over the past 35,000 years (summarized in Brown and Sellmann 

 1973). Radiocarbon dates and composition analyses of peat suggest that 

 tundra existed in the Barrow area for as long as 14,000 years (Brown 

 1965). Based on a number of radiocarbon dates, it is believed that most of 

 the soils and surficial features of the present land surface are not older 

 than 8,000 to 10,000 years and perhaps are considerably younger. 



Mean annual air temperatures on the North Slope of Alaska are 

 below freezing; thus, there is continuous permafrost (perennially frozen 

 ground) beneath the entire area. At Barrow, the frozen layer is 400 m thick 

 (Brown and Sellmann 1973) but there is a layer of soil 25 to 100 cm thick 

 that does thaw each summer. The depth of thaw is influenced by the type 



