of the ground water, as well as upon the perviousness to descending 

 water of the parent rock and the water retaining capacity of its super- 

 ficial portion. The vegetative covering, in its turn, is largely determin- 

 ed by the character of the parent rock or of the soil developed upon this, 

 together with the climate of the locality. Hence, the properties of the 

 parent rock and the climate of the region in which it happens to be 

 exposed will together determine the relative importance of the various 

 soil-forming agencies and accordingly, the character of the resulting 

 soil. 



In general the character of a soil is much more dependent upon the 

 climate of the region in which it is found than upon the nature of the 

 parent rock, or upon the manner of its formation. Thus a granite, 

 a wind-laid silt loam and a lacustral clay may weather to produce soils 

 of a very similiar character when all three have been exposed to the 

 same climate for a sufficient length of time, while soils of an entirely 

 different character might arise on these same formations under other 

 climatic conditions (2, p. 199). 



Accordingly, as the climate of the earth shows a zonal distribution, 

 the soil, unlike any other geological formation, also shows a zonal dis- 

 tribution, similar zones appearing in regular order on the different con- 

 tinents and in both hemispheres (15, map 2) as we pass from the 

 equator poleward, or, in a tropic or temperate region, ascend a high 

 mountain (16, p. 343). Thus, desert soils in the United States resemble 

 desert soils in Africa or Asia and the black prairie soils of the United 

 States resemble the Chernozem of European Russia and Siberia (16, 

 p. 286; 2, p. 231 ; 4, p. 423) and the pampas soils of Argentina (16. p. 

 44 and 114). If one but knows the climate of a region the general 

 character of the soils can be predicted. 



Where the character of the parent rock, its chemical composition 

 or its physical properties, have been such as to leave upon the result- 

 ing soil an impression not overshadowed by the climate the soil is, ac- 

 cording to Glinka, to be designated Endodynamomorphic but otherwise 

 as Ektodynamomorphic (16, p. 35; 27, p. 559). It is with the latter 

 group of soils that the present study is concerned and these may be 

 divided into six classes. 



/. Soils formed zvhcre the mean temperature is high and the preci- 

 pitation very high or fairly high. 



The most of the organic material decays rapidly, causing a low 

 proportion of this in the soil, and the salts resulting from the decay 

 and the weathering of the silicates are completely leached out. The 

 silicic acid derived from the weathering of silicates and alumino-sili- 

 cates is leached out along with the alkali and alkali earth metals, leav- 

 ing behind, in addition to the quartz, the alumina, ferric oxide and 

 titanium oxide. 



The laterites (title-colored soils 10, p. 440) of the moister, and the 

 Red Earths of the drier portions of the tropics belong to this class. 



