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In describing, for valuation purposes, the soil itself, it is 

 desirable, if possible, to characterize it by those great ele- 

 ments which are chiefly regarded by agriculturists as affect- 

 ing the condition of arable land. The terms clay lands, 

 siliceous, calcareous, and peaty, generalize the particulars 

 most important to be known by practical men in reference 

 to soils. 



But as these elementary substances exert unequal influ- 

 ences, according as they are derived from genial or barren 

 rocks, it is evident, that if w r e could be certain of the ori- 

 ginal source from which our soils were derived, we should 

 be able to form a more correct idea of the value and capa- 

 bilities of the land. 



Now in relation to the arable portion of the soil, this 

 would be a work of difficulty and uncertainty. The culti- 

 vation of ages mixes foreign ingredients in the soil, and the 

 gradual increase of decomposed organic matter alters the 

 original combination of elementary substances, so as to 

 make their recognition difficult. 



But the subsoil is not subject to the same influences. It 

 remains in many cases in a state of nature, and lying on 

 the rock from which it sprung, furnishes a surer index of 

 the exact formation and value of the soil. 



A further consideration, which demonstrates the import- 

 ance of examining the nature of subsoils, is derived from 

 the efforts now being made by our best practical agricul- 

 turists to deepen the subsoil, by bringing it gradually up, 

 or turning its capabilities to account by trenching and 

 subsoiling. 



It would be important, therefore, where it is practi- 

 cable, in describing the subsoils of lands of which an accu- 

 rate examination is necessary, to state the formation to 

 which they belong, or of which they are composed. 



The great systems of rocks developed in Ireland are 

 granite in the lofty mountains of Donegal, Down, and Wick- 

 low ; mica slate in Donegal, Derry, and Tyrone ; clay 

 slate in Down, Louth, Wicklow, and Wexford; sand- 

 stone in Longford, Roscommon, Cork, Tipperary, and 



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