SOILS. 75 



It should be borne in mind, further, that in consequence of 

 the highly absorptive and retentive qualities of clay, the rela- 

 tive proportions of lime and of the elements of plant food in 

 the soils, such as potash, phosphates and the like, will in great 

 measure depend upon the amount of the clayey constituent, so 

 that the classification of soils into sandy and clayey carries 

 with it far more than this primary distinction. 



As a broad generalization, it may be said that residual soils, 

 i. e., those which have not been far removed from the parent 

 rock, exhibit the widest variations, while the transported or 

 drifted soils are more uniform in composition. And further- 

 more, the greater the distance the transported soils have been 

 carried from their place of origin, and the oftener they have 

 been taken up and redeposited, the more complete is the sepa- 

 ration of the clayey constituents from the sand, and the more 

 complete is the leaching out of the soluble salts upon which 

 in great measure the fertility is dependent. All this is illus- 

 trated in the changes to be observed in the soils as one goes 

 from inland towards the coast. 



For convenience in the discussion of its soils, the state may 

 be divided into two parts, approximately coextensivie with the 

 Mineral District and the Agricultural District, respectively. 



In the first, the soils are in the main, residual, i. e,, they 

 have been derived from the rocks upon which they now rest, 

 and show, therefore, more or less close relationship to them. 

 In the second, the Coastal Plain or Agricultural District, the 

 Cretaceous and Tertiary formations have been overspread 

 with a mantle of sandy loam and pebbles, transported from 

 elsewhere, and the soils are in great measure made from 

 these materials, modified, however, locally by admixtures 

 with the disintegration and decomposition products of the 

 underlying older rocks. 



The Mineral District. 



As before stated, the soils of the Mineral District are most- 

 ly residual in their nature", and while the parent rocks are 

 sandstones, shales, and limestones, each of these is varied by 

 admixtures with the others, and to such a degree as to give 

 rise to a great variety in the resulting soils. The three prin- 

 cipal varieties are here given, but it will be understood that 



