64 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION.. 



of the Lower Tertiary, and the low basin or trough of the Cretaceous 

 are the principal exceptions to this uniformity. 



Through all this region of the newer rocks there are alternations of 

 nearly level table lands of 500 to 600 feet elevation above tide, bordered 

 by red clay and pebbly hills where the table lands break off towards 

 the water courses. 



The most recent formations, along the alluvial plains of some of the 

 larger rivers and in the vicinity of tJie Gulf coast in Texas and Louis- 

 iana, have almost a dead level surface. 



The topographical features are thus seen to be in great measure, and 

 particularly within the hydrographical basin of the Mississippi, the 

 result of erosion simply. 



The drainage of the greater part of the cotton producing area is 

 into the Gulf of Mexico, and the Mississippi Elver the principal chan- 

 nel. 



The waters of the Carolinas and Eastern Georgia and Eastern Florida 

 find their way into the Atlantic. 



Soils.— The soils which are planted in cotton may be divided into 

 two great classes. 



Those of the first class rest directly upon the rocks from which they 

 have been derived, or at most have been very little removed from their 

 original places ; and hence they are in composition closely related to 

 the underlying rocks, and vary from place to place as these vary. 



The soils of the second class have been transported from their place 

 of origin, and, as a rule, rest now upon rocks with which they have little 

 or no genetic relation. 



Eesulting, as they do, from the commingling of the detritus of widely- 

 separated and very different rocks, these soils, over great areas, present 

 substantially the same features, irrespective of the particular geological 

 formations upon which they have come to rest. 



In general terms, the Paleozoic formations possess soils which have 

 resulted from the decay of the rocks of the country, while the newer 

 formations have been covered with a mantle of sands, pebbles, and 

 loams, which have been brought from greater or less distances, and 

 which in a great measure form the soils and subsoils over the entire 

 area, with the few exceptions presently to be noticed.* 



The drift soils above named, while similar in composition over large 

 areas, are nevertheless in places modified by admixtures with the pro- 

 ducts of the disintegration of the underlying Cretaceous and Tertiary 

 rocks, and in certain localities these disintegrated rocks themselves 

 constitute the soils, as in the black prairie region of Alabama and Mis- 

 sissippi, and in some of the Tertiary i)rairies of these States. 



* It is hardly necessary to say that, with refereuce to the Drift heds from which they are derived, 

 these soils also are eedentary or in place, and the beds of the Drift are, accurately speaking, as much 

 rocks as are, for instance, the limestones of the Silurian age ; sliU, from our point of view, the dis- 

 tinction above made has its justification in its convenience. 



