34 SOILS FROM THE 



the object, to be attained is surrounded with difficulties, and where every ray of light is 

 wanted to illuminate dark and obscure points. Upon agriculture all the modern sciences 

 send their lights, some more and some less ; all, however, impart something, and lend 

 their aid to its promotion. In iliis office geology is behind none other, unless it be che- 

 mistry, whose range is not only great, but minute, affi;cting every and all departments. 

 A great many facts strictly geological have an important bearing upon the subject before 

 us ; such as the nature of the rock, its structure and position, its composition, its relations 

 to moisture, and liability to solution. The position of the rocks of a district, as has been 

 already remarked in the lirst chapter, is always an important point, and in some cases all 

 that is essentially recpiisite ; for they often add value to their possession, even when they 

 can not be turned to account directly in the cultivation of the soil. 



Under the influence of these considerations, and others of minor importance which it is 

 unnecessary to state, I propose to give first of all a recapitulation of the geology of New- 

 York, witli a view of applying all the facts which bear upon agriculture to its illustration. 

 For the convenience of description, I shall pursue the plan adopted in the geological re- 

 ports, namely, that of describing the rocks in the ascending order ; and this will lead me 

 to speak of them in the order of the districts which I have already briefly described, and 

 into which the State has been divided. 



The six districts coinciding nearly with six groups of rocks, each of these groups respec- 

 tively impart to the overlying soil some of its distinguishing characters, or in a good mea- 

 sure make it what it is. Modifying influences, however, independent of the geological 

 formation, have done something as diluvial or transporting agents, by which soils origi- 

 nating and formed at a distance have been brought to and distributed over adjacent dis- 

 tricts. Still it will be found on examination that the underlying rocks have given a 

 stronger character to the soft materials than has usually been supposed, leaving out of 

 view some areas in every district where drift has lodged in deep beds. 



In estimating the amount of soil furnished by groups of rocks, we are necessarily obliged 

 to observe the nature of the masses. Many of the shales and slates, and they occur in 

 almost every group, disintegrate rapidly, the action being favored both by water and frost : 

 the first, penetrating between tlic laminae, partially separates them ; and in some instances 

 no other agent is required to effect an entire destruction of a stratum, especially where 

 wetting and drying alternately occur. In other cases, the assistance of frost is required 

 to eflect a complete reduction of the strata to soil. 



Limestones are liable to a constant loss of material by solvent properties of rain-water, 

 which holds carbonic acid in solution ; and this operation is favored by a rough or uneven 

 surface, wliere the water stands for a time. On a polished surface, the action of water 

 and other agents is very slow and inconsiderable even after the lapse of several years, as 

 is proved by the durability of (lie marbles used in the construction of monuments, and by 

 that of other rocks when carefully smoothed; whereas upon the exposed surfaces of quar- 

 ries, the sloping sides are often deeply grooved by the water which slowly trickles over 

 their surfaces. 



