220 ELEMENTS OF SOILS. 



The same kind of soil bottoms the vnllies far south : even the Chemung vallies are greatly 

 inck'ljtetl to the soft rociis of Onondaga for fertile soil, but it does not reach the hill-sides. 



The soils of the primary rocks, especially those of Franklin county, have acquired much 

 additional material from tiie Hudson-river shales of Canada ; and a vast amount from the 

 north is lodged on the northern slope of Franklin and Clinton counties, from Lake Cham- 

 plain to the St. Lawrence river. It does not extend very far south, however, and most of 

 the soil of this primary region is derived from the rocks themselves. 



In proceeding, then, to the examination of the soils of a district, especially if we wish 

 to make a comparison between them and the underlying rock, the first step is to determine 

 whether our soil is from a drift bed, or if it is filled with many large and small rounded 

 pebbles of some other rock ; if so, we can not get much light upon the nature of the soil 

 from tlie rock beneath. The pcbl>!es, in this case, are sufficient of themselves to give 

 some information of the probable nattue and composition of the soil : if they consist of 

 limestone, lime v/ill probably be found in the soil ; if of slate or shale, there is the same 

 indication, though it is not so important; but if the pebbles consist of silex, or sandstone 

 gravel, the inference is decidedly negative so far as lime is concerned. Siliceous pebbles 

 exert simply a mechanical effect, but that effect is valuable. 



IV. ELEMENTS OF SOILS. 



Properties and functions of the elements in their individual and combined 



capacities. 



Of the fifty-eight elements of matter, only about fifteen enter into the composition of 

 vegetables, if we disregard marine plants. These fifteen elements are all found in soils, 

 and are all necessary and essential parts of it. Each may be said to have its peculiar 

 function : it may be entirely useless so far as it is considered an element of a particular 

 vegetable, but highly important in imparting a certain condition to the soil. The office 

 of these elements is twofold : first, as performing a specific fimction in the organization 

 of a living body; and secondly, as giving a particular state or condition to the soil: the 

 first office is vital, the second mechanical. 



We have been considering elements, by which is usually meant a simple undecomposed 

 body, as iron, gold, silver, oxygen, chlorine. This is not the state, however, in which 

 they enter into the soil, or into plants; in their uncombined state, they are unsuited to 

 either place. Hence we always find iron combined with some other element ; and so also 

 of sulphur, nitrogen, hydrogen, carbon, etc. The diamond (pure crystallized carbon), 

 reduced to an impalpable powder, would be totally valueless as food for plants. Oxygen 



