ROCKS AND SOUS 



79 



CLIMATE 

 dry cold 



wet cold 



dry hot 

 VEGETATION 



wet hot 



MAJOR SOIL GROUPS 



perpetual snow and ice 



tundra soils 



podsols 



"D 



c Ul 

 o — 



eS 



o oi 

 ^ iS 



Ul TD 



C 

 D 



■•-* 



IJ 

 C 



4) 



So 



Q-Oi 

 "D 



podsolic 



gray-brown 

 podsolic 



red a. yellow 

 podsolic 



loteritic 



Figure 5.2 Distribution of climotic types; vegetotion ond mojor soil 

 groups on a climatic basis. 



The soil orders have a definite relationship with 

 the factors of soil formation. Only zonal soils are 

 fully mature and reflect climate and vegetation 

 (Figures 5.2, 5.3, 5.4, 5.5). Because vegetation must 

 also be mature (stable or climax) and reflect climate, 

 mature soils can be said to reflect climate alone. 

 However, the soil in many localities is not mature. 

 It might be hardly dififerentiated, or very young. 

 Such a soil has little or no layering and is termed 

 azonal. In addition, there are substrates intermediate 

 between azonal and zonal. These are the mtrazonal 

 soils, which are held back from full maturity by local 

 land forms, parent material, and/or insufficient time 

 for complete formation. Therefore, only zonal soils 

 show close relationship to climate and vegetation, 

 intrazonal soils show much less association, and 

 azonal soils have very little if any direct association. 



ZONAL SOILS 



The four processes of zonal soil formation disclose 

 the importance of climate and vegetation. The 

 processes are gleization which forms Tundra soil, 

 podsolization which forms Podsols, laterization which 

 forms Lateritic soil, and calcification which forms 

 Chernozem, Chestnut, Brown, Sierozem, and Red 

 Desert soils. 



Gleization includes the physical, chemical, and 

 biological processes in arctic regions and other places 

 where soils are always wet but have few salts. Under 

 these conditions, a structureless but compact and 

 sticky layer develops beneath the subsoil and char- 

 acterizes a blue-gray Tundra soil. Full development 

 of this soil normally requires tundra vegetation. 



Podsolization occurs in cool, moist climates and is 

 the process of slow organic decay in forests. It in- 

 volves the production of certain acids and results in a 

 variety of Podsols in northern and temperate forests. 

 True Podsol is generally associated with northern 

 coniferous forests, Gray-Brown Podsols with true 

 deciduous forest, and Red-Yellow Podsols with 

 mixed deciduous-coniferous forest or with southern 

 coniferous forest. 



Laterization is a distinctive process in warm, moist 

 climates. The process leads to Lateritic soils that 

 usually have rainforest vegetation. Also, the process 

 includes certain peculiarities and selectivity in leach- 

 ing. 



Calcification is found in arid areas and, for this 

 reason, features less leaching, especially of calcium 

 and magnesium. The most typical calcification soil 

 type is Chernozem, or grassland, soil. This soil has a 



