418 REPORT OF OFFICE OF EXPERIMENT STATIONS. 



oonvtM*si()n from marshes to well-drained fields. Thus it is that 

 nature has forced upon man the necessity of exercising; his ingenuity 

 atid lal)or in wresting these productive lands from their water-ridden 

 state, even as centuries ago the brave and imlustrious Hollanders 

 wrested their empire from the sea. 



Many of the streams antl bayous now isolated have served in times 

 past as mouths of the Mississippi or as overflow outlets in times of 

 flood, and they have been instrumental in the distribution of the rich 

 silt-laden waters and in the gradual advance of the coast line. 



Even before the construction of the artificial levee system, there was no raising 

 ef the general level of the marshes during periods of normal flow and probably little 

 sedimentation at the river bed excepting at ite mouth, the most of the material which 

 wa.s carried in .suspension to the lower portion of the river being carried out and 

 deposited in the Gulf. As the river rose, however, the waters constantly sought 

 additional outlets through the various bayous of the delta country. At times of 

 extreme high water there was a general breaking over the l)anks of the river and 

 its outlet-s. It i.s probable that the most of the building up of the lands above sea 

 Idvel has been done at such times. 



The fact of the silt-bearing capacity of water being directly 

 dependent upon the velocity is clearly demonstrated by observing 

 the natural embankments formed by streams of various sizes. In 

 the case of smaller streams when the water overflows, its force is soon 

 spent and the silt is quickly deposited near the stream, forming 

 narrow ridges with steep side slopes, while those formed by large 

 streams are broad with slight slopes. Three typical examples, show- 

 ing this difference and the manner in which the land surface has 

 been raised on the marshes, are given in figure 1, A, B, and C. 



The sections were taken as follows: 



A — From the right bank of the Mississippi River across the Willswood plantation, 

 about 10 miles above New Orleans. This section is about 2 miles long and a i)art 

 of the lands crossed have been under cultivation for a great many years, while those 

 farthest from the river were reclaimed only twelve or fifteen years ago. The lower- 

 ing of the surface of the cultivated and drained fields due to the .shrinkage of humus 

 soils is heie well illustrated. There are many examples of highlands having been 

 built up for much greater distances from the river than this, but as such accretions 

 are indirect, on account of being formed by a number of small bayous or temporarily 

 contracted areas of overflow which assisted in maintaining the velocity, these have 

 not lieen considered as being typical. 



[ B— The right bank of Bayou La Fourche at Lockport, extending back through the 

 village of Lockport and the lands of the Smithport Planting Company to Lake Fields. 

 Until 1903, Bayou La Fourche served as an overflow outlet for the ML=!sissippi River, 

 the opening at Donaldsonville not having been permanently closed until that year. 



C — This is a very small bayou running through the lauds of Dr. I. D. Fay, about 

 4 miles west of Lockport. The abrupt rise of the ridge from the surrounding marshes 

 is especially noticeable and is characteristic of smaller bayous. 



Important exceptions to the foregoing general statement as to the relation between 

 the size of bayous and the ridges built by them are frequently found. Prominent 



