258 black. PERMAFROST [Ch. 14 



ment of the north for decades. Now with the recent progress in avia- 

 tion, and because of the strategic importance of the north, active con- 

 struction and settlement for military and civilian personnel must in- 

 crease, and the problems of permafrost must be solved. 



Fortunately we can draw on the vast experience of our northern 

 neighbors. Their engineers have shown that it is 



... a losing battle to fight the forces of frozen ground simply by using 

 stronger materials or by resorting to more rigid designs. On the other hand, 

 the same experience has demonstrated that satisfactory results can be achieved 

 and are allowed for in the design in such a manner that they appreciably 

 minimize or completely neutralize and eliminate the destructive effect of frost 

 action . . . Once the frozen ground problems are understood and correctly 

 evaluated, their successful solution is for the most part a matter of common 

 sense whereby the frost forces are utilized to play the hand of the engineer 

 and not against it. ... it is worth noting that in Soviet Russia since about 

 1938 all governmental organizations, municipalities, and cooperative societies 

 are required to make a thorough survey of the permafrost conditions according 

 to a prescribed plan before any structure may be erected in the permafrost 

 region. [Muller, 1945, pp. 1-2, 85-86.] 



Specifically we must think of permafrost in construction of build- 

 ings, roads, bridges, runways, railroads, dams, and reservoirs, in prob- 

 lems of water supply, sewage disposal, telephone lines, drainage, exca- 

 vation, ground storage, and in many other ways. Permafrost can be 

 used as a construction material or as a base for construction, but steps 

 must be taken to insure its stability. Otherwise it must be destroyed 

 and appropriate steps taken to prevent it from returning. 



BIOLOGIC SIGNIFICANCES 



Permafrost, by means of its low temperature and ability to prevent 

 runoff, is a potent factor that aids in controlling vegetal growth in the 

 Arctic and sub- Arctic (Mosley, 1937). Many places have semi-arid 

 climate yet have luxuriant growths of vegetation because the perma- 

 frost prevents the loss of precipitation through underground drainage 

 (low evaporation is possibly as important). Such conditions are 

 natural breeding environments for mosquitoes and other insects. 



Conversely, luxuriant growths of vegetation, by insulating the per- 

 mafrost in summer, prevent deep thawing, restrict food supplies, and 

 augment cold soil temperatures. Hence those species with deep root 

 systems, such as certain trees, are dwarfed or absent. 



Raup (1941, 1947) points out that much of arctic soil is unstable 

 because of frost action (commonly associated with permafrost) and 



