SOILS. 77 



the underlying country rock these Lafayette soils are at their 

 best highly siliceous loams, usually of deep red color from 

 iron oxide. They are well drained, well situated and among 

 the most desirable of our farming lands, because of these 

 qualities and of the ease of working and capability of im- 

 provement. At the other extreme they are very sandy and 

 comparatively infertile in the natural state, yet some of the 

 most valuable truck farms of Southern Alabama have soils of 

 this class 



While the Coastal Plain formations, Cretaceous and Ter- 

 tiary, consist prevalently of sands and clays in many alterna- 

 tions, yet there are, two great limestone formations intercalated, 

 viz., the Selma Chalk and the St. Stephens Limestone, the for- 

 mer of Cretaceous, the latter of Tertiary age. 



The Selma Chalk is about 1,000 feet in thickness, is a 

 rather soft chalky rock carrying from 10 per cent, to 50 per 

 cent, clayey matters, the middle third of the formation hold- 

 ing from 10 per cent, to 25 per cent, of clay, while the uppier 

 and lower thirds contain larger amounts. 



The St. Stephens Limestone, in its lower part, is also an 

 argillaceous clayey limestone much like the Selma Chalk, but 

 the upper part is a purer rock containing only on an average 

 about 10 per cent, of insoluble matters. 



Now in those parts of the Coastal Plain where the under- 

 lying country rocks are sands and clays, the resulting soils 

 from these do not differ essentially from the surface loams 

 of the Lafayette itself, and needs therefore no special mention. 



But in those belts on the other hand, where the limestones 

 of the Selma Chalk and of the St. Stephens underlie and con- 

 stitute the country rocks, the soils show marked departure 

 from the prevailing type of Coastal Plain sandy loams. From 

 these areas the Lafayette sands have often been in great part 

 swept away by erosion, and the soils are in a measure resi- 

 dual, being the insoluble clayey residues from the diecay and 

 disintegration of the limestones. 



Like all clayey soils derived from limestones, they are of 

 exceptional fertility, and make the very best farming lands 

 of the state. Such are the soils of the great Black Belt or 

 Canebrake Belt of Central Alabama, and those of the Lime 

 nills, and Hill prairies of the southern part of the state. Rem- 

 nants of the Lafayette mantle occur at intervals through all 

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