174? OF THE MISSISSIPPI, 



mile in breadth, which probably equals its mean breadth 

 from Yazooz to its mouth. 



The margin of the river is the highest land to be found in 

 the valley of the Mississippi. — As the river overflows its banks, 

 the waters immediately begin to deposit their grossest particles, 

 which are chiefly sand and black marl, and in their progress 

 backwards this deposition is continued until at length, a mat- 

 ter is deposited so highly levigated that, upon the retiring of the 

 waters, it assumes a compactness and solidity resembling pitch : 

 when the river by disruption alters its course, and new accumu- 

 lations of slime sand and marl are laid upon this very compact 

 earth, a false belief might be induced that this solid soil is not 

 the offspring of the river, but the original parent earth coeval 

 with the Mississippi itself, upon which this great river had af- 

 terwards deposited the rich spoils of the northern regions, borne 

 down by its mighty tide; this compact soil I have found at the 

 depth of from 10 to 30 feet; and in other situations no appear- 

 ance is to be seen of any other than the common soil formed 

 of the mud of the river. The soil near the river is sandy, par- 

 ticularly that which has been lately formed; from a quarter to 

 half a mile from the margin of the river the sand is less appa- 

 rent, and it loses its name of ' terre sablonneuse,' acquiring that 

 of * terre grasse,' being the richest black marl, with a moderate 

 admixture of sand; at greater distances, and frequently at some 

 depth under the last mentioned soils, is found the above men- 

 tioned compact earth, called glaise (potters earth); it is no 

 doubt eminently adapted to the use of the potter, though hi- 

 therto not much applied to the manufacture of earthen ware. 

 Upon all lands long subject to culture and defended from the 

 inundation, although near to the margin, the appearance of 

 sand is almost lost, but it is evident from the friability of the 

 soil, and the facility with which it is cultivated, that a large por- 

 tion still remains intimately mixed with it, whereas the terre 

 grasse (unmixed or pure marl) yields with difficulty to the 

 plow; it exhibits proofs of the richest marl, a slight shower 

 causing it to crumble into powder after being turned up; yet as 

 our climate is exposed to sudden and violent falls of rain with 



