276 T. O. MABRY 



Per cent. 



Silica (Si0 2 ), - - - - 78.55 



Ferric oxide (Fe 2 3 ), - - 14.88 



Water, - - - - - 1.51 



Sulphuric acid (H 2 S0 4 ), - - 1.03 



Lime (CaO), - - - 1-944 



Alumina (A1 2 3 ), - - - 2.06 



Total, .... 99-974 



Perhaps the most notable characteristic of the brown loam is 

 its general disintegrated, " rotten" appearance, with the entire 

 absence of anything simulating stratification in the loam proper, 

 notwithstanding the fact that the particles composing it are 

 usually fine and such as ought, it seems, to have been neatly 

 stratified if deposited under ordinary conditions, and not sub- 

 jected to subsequent atmospheric and aqueous action. This 

 subject will be more fully discussed under the general head, 

 "Origin and Age of the Loess-Loam." 



II. STRATIGRAPHIC RELATIONS AND DISTRIBUTION OF THE BROWN 

 LOAM OF NORTH MISSISSIPPI. 



According to Hilgard {Agriculture and Geology of Mississippi, 

 pp. 197—198), "the yellow, brown, or reddish loams which have 

 been repeatedly mentioned as forming the surface, and therefore 

 essentially, the soils of the greater portions of the State of 

 Mississippi constitute to all appearance an independent aqueous 

 deposit, posterior to the Orange Sand (Lafayette) and the Bluff 

 formation, and anterior to the alluvial formations of the present 

 epoch. The great thickness which this loam stratum attains in 

 some regions, its distinct definition as well as its comparative 

 independence as to its character of the formations immediately 

 underlying, preclude its being claimed as a mere surface disinte- 

 gration of the older formations. The nature of its materials and 

 the entire absence of stratification lines distinguish it sufficiently 

 from the Orange Sand where it immediately overlies the latter ; 

 while the absence of any large amount of lime, except where it 

 is in immediate contact with strongly calcareous formations, the 



