The yellow soils of southern France {21 , p. 600) and of Japan are re- 

 lated to the Red Earths, the removal of the silica being charcteristic 

 of only the later stages as in the laterites. In the latter, in various 

 places, the concentration has proceeded so far as to make such soils 

 serve as a source of metallic iron, really as a low grade ore. 



//. Soils xvhcrc the precipitation is lower and the temperature 

 much loxver than in the preceding, as over northwestern and western 

 Europe and in the United States east of the Mississippi river. 



The soluble salts are leached out, the carbonates removed from the 

 upper layer, and a certain amount of iron transported from tlie upper 

 to the lower layers (^27, p. 554). Only part of the organic matter is 

 lost rapidly, thus permitting the accumulation of a comparatively large 

 amount in the upper layers. In the colder, moister regions there result 

 podsols, characterized by a whitish or gray horizon near the surface 

 with a concentration of iron at a greater depth and a markedly acid 

 reaction. Along with the iron, manganese, calcium, magnesium, potas- 

 sium and sodium more or less phosphoric acid is leached out of the 

 upper layers and redeposited with the iron and manganese at a lower 

 horizon (15, p. 78). Where the temperature is higher, either degrad- 

 ed chernozems, brown earths or gray forest soils develop. These 

 show less translocation of iron and little or none of phosphoric acid. 

 Both the true podsols and the brown or gray forest soils develop under 

 forest conditions. 



///. Soils formed 7cliere the precipitation, evaporation, tempera- 

 ture and topographical conditions cause a grassla)id I'egetation to hold 

 its own against the forest. 



The abundant growth of grasses exhausts tlie soil moisture supply 

 and causes a delayed decomposition of their remains with the result 

 that the organic matter content of the soil is high. The plants, being 

 chiefly annuals, biennials, or short-lived perennials, frequently con- 

 tribute both root and stem, as well as leaf, to the soil forming agencies 

 and the organic matter is increased as deeply as the roots penetrate. 

 Alkali salts are removed and the carbonates largely leached out of the 

 upper layers are deposited, for the most part, in the base of the zone 

 of maximum root pentration. Gypsum is redeposited at a still lower 

 level, if at all. Alkali salts and carbonates formed by the action of car- 

 bon dioxide upon the silicates behave like the original soluble salts and 

 carbonates, while the resulting silicic acid remains in the upper layers 

 (2, p. 315). The class includes the Black Earths or Chernozems of 

 Russia and the black and part of the brown prairie soils of the Ignited 

 States and Canada (21, p. 207 and 338). 



