WESTERN DISTRICT. 287 



the composition of the green shales of the Salt group, and the soil derived from them. It 

 is also an interesting fact that this soil contains uniformly less calcareous matter than that 

 of the Marccllus slate, although the former has twice or thrice as much carbonate of lime 

 in its composition as the latter. This was a perplexing point at first ; but if it is true, as 

 it seems to be, that more of the organic salts are formed in the green shales in the course 

 of decomposition, than in the Marcellus slate, the case may be regarded as explained. 

 These salts, together with the salts of sulphuric acid, are soluble, and wash out or fdter 

 through the soil : hence the bitter waters of so many lakes, and the great abundance of 

 tufa which accumulates on the slopes and declivities wherever the percolating waters are 

 brought to the surface. 



The soil of the valley of the Genesee possesses essentially the same characters as that of 

 Onondaga county. This statement is borne out by the following analyses. Thus Mr. 

 Harmon's wheat soil, in Wheatland, gave of soluble matter 1'41, containing organic 

 matter 0"25, and saline matter 1"16, from which I obtained, after ignition, 0'52 of a grain 

 of carbonate of lime, besides chlorine and sulphuric acid. The subsoil (200 grs.) , treated 

 with water, gave 3 '25 grains of soluble matter, of which 1'63 was organic and 1'62 

 mineral salts. This combination yielded 



Carbonate of lime 0*75 



Sulphate of lime 0-22 



Magnesia and alumina 0*46 



Chlorides of calciumand magnesium 0-20 



1.63 



The subsoil in this case is more tenacious than the surface soil, and illustrates the fact 

 which is often referred to by agricultural writers, that clay bottoms and an impervious 

 hardpan hold or retain the soluble parts of the surface soil, especially when under cultiva- 

 tion. In this instance the subsoil is strictly a stiff clay, and so compact and impervious 

 that it necessarily retains water and the soluble matters which are carried down by filtration. 

 It fi-equently happens, however, that an analysis of a subsoil gives essentially the same 

 result as the surface soil. This is the case where a soil is deep, and where consequently 

 the lower materials differ but little mechanically from those of the surface ; and as many 

 of the western soils consist of deep beds of drift or the debris of shales, it is highly impro- 

 bable that the soil and subsoil should give results differing essentially from each other : 

 thus it is no uncommon circumstance for the earth from deep excavations to bear a heavy 

 burden of corn or wheat the first season succeeding its exposure. The same fact is well 

 known, too, in respect to the new and fresh soil from the shales of the Salt group. 

 This is owing in part to the organic matter contained in the rock, and also to the fineness 

 of its particles. These properties fit the abraded materials for the food of plants, so far as 

 soils supply the wants of vegetation. The debris of granite, and other primary rocks, 

 seems to require a long exposure to the air, and to the influences of light, water, carbonic 



