WET LANDS OF SOUTHERN" LOUISIANA. 9 



Area West of the Atctiafalaya River. 



ORTGIN AND FORMATION OF SOILS. 



Most of the land of this section consists of recent coastal plain deposits 

 rather than of Mississippi River alluvium, and surface conditions are some- 

 what different from those encountered in the eastern or delta section of the 

 State. Instead of a succession of ridges and shallow lakes, such as occur in 

 the delta section, we have a costal plain rising gradually from south to north. 

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

 through which the rivers have cut channels. Immediately back of the ridges 

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

 ally to the north, so that at a distance of some 5 to 10 miles inland they be- 

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

 Calcasieu, and the Sabine, still deposit alluvium, and since the coast line was 

 elevated these streams have extended considerably 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 widen gradually as the streams approach the Gulf. These alluvial 

 strips still are 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. 



The Bureau of Soils has not made surveys of this section, but has examined 

 and classified the soils immediately north of it. The various clays, clay loams, 

 silt loams, and sanely loams are described in detail in publications of that 

 bureau. 1 Toward the Gulf the above-enumerated soils are overlain by 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 paragraph 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. As noted above, the subsoils of this 

 portion are the solid loams, etc., of the higher land, thus affording a firm foun- 

 dation quite different from the soft, yielding alluvial silt of the Mississippi Delta 

 swamps. Overlying this subsoil occurs a shallow deposit of partly alluvial silt 

 caused by local erosion and weathering. There is little or no muck on the sur- 

 face of the higher and better-drained portions, although the silt of the top 6 

 inches is rich in vegetable matter due to the decay of the grasses. These por- 

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

 drought ordinary wagons can be driven over them. Toward the south, how- 

 ever, the land is water covered practically all of the time, and a layer of muck 

 has formed from decaying prairie grass. In its essential characteristics this 

 muck is very similar to that of the Mississippi Delta section. It averages from 

 G 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 en- 

 tirely 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 fea- 

 ture, as most of it is so shallow that the cultivation soon will extend into the 



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

 30444°— Bull. 052— 18 2 



