Ch. 14] GEOLOGIC RAMIFICATIONS 255 



voirs, and commonly causes a concentration of organic acids and of 

 mineral salts in suprapermafrost water. In discontinuous permafrost 

 zones, and less so in areas of sporadic permafrost bodies, ground-water 

 movements are interrupted or channelized. Quality of water, too, can 

 be materially affected by the storage for centuries and subsequent re- 

 lease by thawing of organic and inorganic materials (Kaliaev, 1947) . 

 In fact, our present conceptions of ground-water reservoirs, ground- 

 and surface-water movements, infiltration, quality of water, and so on, 

 must be reconsidered in light of another new geologic formation, gen- 

 erally not uniform in composition or distribution, that transcends all 

 rock and soil formations. Furthermore, it must be considered as much 

 in the light of past as of present conditions. 



It is well-known that in cold climates physical disintegration (frost- 

 splitting, congelifraction) plays a more important role than chemical 

 weathering. The repeated freezing of water-saturated materials and 

 the growth of ice crystals in numerous small pores, cracks, joints, 

 cleavage planes, or partings is by far the most important destructive 

 process. Taber (1943a) has shown that, without water, disintegration 

 is generally much slower. Permafrost is one of the most important 

 agents in keeping the soils supersaturated (containing more water than 

 pore space — a suspension) and in keeping many rock fragments wet. 



It is less widely known that mass-wasting processes in the Arctic 

 and sub-Arctic are instrumental in the transport of tremendous vol- 

 umes of material. With the exception of unbroken bedrock, the ma- 

 terials on the surface of slopes greater than 1° to 3° are on the move 

 everywhere in summer. The amount of material involved and the 

 rapidity of such movements impress all who have studied them (Wash- 

 burn, 1947). 



Permafrost, on thawing slightly in summer, supplies a lubricated 

 surface and additional water to some materials probably already 

 saturated. Hence solifmction, mud flows, and other gravity move- 

 ments take place with ease and, in favorable locations, even supply 

 material to streams faster than the streams can remove it (Wahr- 

 haftig, 1949). Bryan (1949) has coined the term "cryoplanation" to 

 cover such processes, including also frost-heaving normal to slopes and 

 settling vertically, which in the Arctic are instrumental in reducing 

 the landscape to long, smooth slopes and gently rounded forms. Such 

 physiographic processes are only partly understood and their effects 

 only qualitatively known (Bryan, 1949) . 



Permafrost, by aiding in maintaining saturated or supersaturated 

 conditions in surficial materials, indirectly aids in frost-stirring (con- 

 geliturbation) , frost-splitting, and mass-wasting processes so that, in 



