are located in three physiographic provinces - the Yukon-Tanana Upland 

 Section of the Northern Plateaus Province (West Fork Tolovana River and 

 McManus Creek), the Tanana-Kuskokwim Lowland Section of the Western Alaska 

 Province (two Tanana River sites), and the eastern portion of the Alaska 

 Range Section of the Alaska-Aleutian Province (Phelan Creek) (Wahrhaftig 

 1965). 



The Yukon-Tanana Upland Section is characterized by rounded ridges 

 and flat, alluvium floored valleys (Figure 8). Surface deposits tend to 



<^;k . Ai 



Figure 8. Typical terrain in the Yukon-Tanana Upland 

 Sect i on. 



coarse and fine-grained alluvium and colluvium. Bedrock exposures are gen- 

 erally limited to upper slopes and ridges. The area is underlain by discon- 

 tinuous permafrost and is subject to extreme temperature ranges, from -45 C 

 in the winter to 32 C in the summer. The average annual precipitation is 

 33-35 cm, which includes 130-150 cm as snow. 



59 



