DRAINAGE OF WET LANDS OF SOUTHERN LOUISIANA. 15 



section we have a coastal plain gradually rising from south to north. Along the 

 immediate coast line there is a more or less unbroken sandy ridge through 

 which the local rivers have cut channels. Immediately in the rear of the ridges 

 are stretches of salt marsh very little above sea level, but which gradually rise 

 to the north so that at a distance of some 5 to 10 miles inland they become 

 fresh-water marsh. The larger streams, such as the Mermentau, the Calcasieu, 

 and the Sabine are still depositing alluvium, and since the coast line was ele- 

 vated these streams have considerably extended the land adjoining them. As 

 the waters of these outlets are very sluggish and are not heavily loaded with 

 silt they have not built up large ridges along the immediate river banks. The 

 alluvial portion is nearly level and the strips of alluvial land along the channels 

 gradually widen as the streams approach the Gulf. These alluvial strips are 

 still in process of formation and of elevation by deposition, since at each high 

 water the adjoining lands are flooded, the rivers not having been leveed. 



CLASSIFICATION AND EXTENT OF SOILS. 



As before stated, the Bureau of Soils has not made surveys of this section, 

 but has examined and classified the soils immediately north of it. These vari- 

 ous clays, clay loams, silt loams, and sandy loams, are described in detail in 

 publications of that bureau. 1 Toward the Gulf the above-enumerated soils are 

 overlaid with muck and alluvial deposits and thus become subsoils. 



The lands of this section might be divided into two main divisions, as indi- 

 cated in the paragraphs on origin and formation: (1) The general wet prairie 

 land, with a comparatively shallow deposit of silt and muck on the surface; 

 and (2) the strips of alluvial land along the river channels or streams. The 

 first class includes the great bulk of the lands of this section. As noted above, 

 the subsoils of this portion are the solid loams, etc., of the higher land, thus af- 

 fording a solid foundation which is quite different from the soft yielding allu- 

 vial silt of the Mississippi Delta swamps. Overlying this subsoil occurs a 

 shallow deposit of partly alluvial silt caused by local erosion and weathering. 

 On the higher and better drained portions there is little or no muck on the 

 surface, although the silt of the top 6 inches is rich in vegetable matter due 

 to the decay of the grasses that grow on these sections. These portions are 

 covered with water only during the rainy season, and during times of long 

 drought ordinary wagons can be driven over them quite safely. Toward the 

 south, however, the land is water-covered practically all of the time, and a 

 layer of muck has formed from decaying prairie grass. In the essential 

 characteristics this muck is very similar to that of the Mississippi Delta sec- 

 tion. It averages from 6 to 18 inches in thickness, although in low depressions 

 and shallow bayous it may be several feet deep. Owing to the absence of any 

 extensively silt-bearing streams the muck of these wide level prairie sections 

 is- composed almost entirely of vegetable matter, and its dry weight is less than 

 that of the average muck of the delta section. This, however, should not be 

 an. undesirable feature, as most of it is so shallow that the cultivation will soon 

 extend into the silt below. As the coast line is approached, as noted before, the 

 marsh becomes salt, but it is covered with practically the same depth of muck. 

 In various places in this section there are broad zones where the silt deposit 

 between the muck and the underlying subsoil is quite deep, perhaps 3 or 4 

 feet, and has a chocolate-brown color quite similar to the soil of the Sharkey 

 clay regions. These areas are more numerous in the lower portions of the 

 prairie. 



1 U. S. Dept. Agr., Field Operations of the Bureau of Soils, 1901 and 1903. 



