74 MINERAL RESOURCES OF ALABAMA. 



SOILS. 



It would be obviously out of place in a document like the 

 present to attempt to give an account of the many soil varie- 

 ties of the state and their adaptation to various crops. This 

 subject has been treated somewhat in detail in our Agricul- 

 tural Report, 1 88 1 -2. 



But inasmuch as the soils constitute the most recent of 

 our geological formations, they must be included among our 

 mineral resources, and certainly no one of these mineral re- 

 sources can be compared with them in importance and inter- 

 est to every citizen of the state. 



A general discussion of the soils, from the point of view 

 of their geological relations seems, therefore, to be called for 

 here. 



Since the soils have been derived from the disintegration 

 and decay of the older rocks, a geological map might, to a cer- 

 tain extent, serve also as a soil map, but these products of 

 decomposition now rarely rest upon the parent rock, but have 

 been removed more or less remotely from their place of ori- 

 gin, and after various admixtures have been redeposited upon 

 foreign terranes with which they have no connection; again, 

 many of the parent rocks of now existing soils have them- 

 selves in their turn been soils derived from still older rocks, 

 have been deposited as sediments, compacted, elevated and 

 again disintegrated and decomposed into soils. These are 

 some of the difficulties which we meet with when we attempt 

 to trace a soil back to its origin. 



Another difficulty comes from the fact that soils from vari- 

 ous sources have often very similar composition, for all soils 

 are essentially the insoluble residues left from the weathering 

 of older rocks, and these insoluble residues, from whatever 

 parent rock derived, are mixtures in varying proportions of 

 sand and clay, with small amounts of the soluble salts derived 

 from these rocks and not yet completely leached out of the re- 

 sulting soils. It follows, therefore, that soils from whatever 

 source derived, will differ from each other mainly in the rela- 

 tive proportions of the sandy or siliceous and the clayey con- 

 stituents. 



