220 ELEMENTS OF SOILS. 



Tin* sumo kind of soil bottoms i lie rallies far Bontb : even the Chemung rallies are greatly 

 indebted la the w>fl rocks of Onondaga for fertile soil, bul it does not reach the lull-sides. 



The soils of the primary rocks, especially those of Franklin count] . have acquired much 

 additional material from the Hudson-river shales of Canada; and ;i vasl amount from the 

 north is lodged on the northern dope of Franklin and Clinton counties, from Lake Cham. 

 plain to tin- St. Lawrence river. Ii does nol extend »erj far south, however, and most of 

 the seil of ilus primary region is derived from the rocks themselves. 



In proceeding, then, to the examination of the sods 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 man] large and small rounded 

 pebbles o( some other rock ; il" so, we can not gel much lighl upon the nature of the soil 



from the rock beneath. The pebbles, in this case, an- sufficient of themselves u> give 

 some information of the probable nature anil composition of the soil : if they consist of 

 limestone, time will probably be found in the soil ; if of slate or shale, there is the same 

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

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

 exert simply a mechanical effect, hut 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 he said to have its peculiar 

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

 vegetable, hut highly important in imparling a certain condition to the soil. The office 

 of these elements is twofold : first, as performing a specific function 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 slate, 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 



