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Ch. XIX.] 



MUD-LUMPS OFF THE MOUTHS. 



447 



New 



depth of several yards below the level of the sea, that the soil 

 of the delta contains innumerable trunks of trees, layer 

 above layer, some prostrate, as if drifted, others broken off 

 near the bottom, but remaining still erect, and with their 

 roots spreading on all sides, as if in their natural position. 

 In such situations they appeared to me to indicate a sinking 

 of the ground, as the trees 



must 



grown m 



marshes above the sea-level. In the higher parts of the allu- 

 vial plain, for many hundred miles above the head of the 

 delta, similar stools and roots of trees are also seen buried in 

 stiff clay at different levels, one above the other, and exposed 

 to view in the banks at low water. They point clearly to the 

 successive growth of forests in the extensive swamps of the 

 plain, where the ground was slowly raised, year after year, 

 by the mud thrown down during inundations. These roots 

 and stools belong chiefly to the deciduous cypress (Taxodium 

 distichum) and other swamp trees, and they bear testimony to 

 the constant shifting of the course of the great river which is 

 always excavating land originally formed at some distance 

 from its banks. 



The most southern 



Mud-lumps off the mouths of the river.— 

 or seaward part of the delta of the Mississippi is a long- 

 narrow tongue of land protruding itself for fifty miles into 

 the Gulf of Mexico, and terminating in several arms or 

 passes, as they are called, which have a fan-shaped arrange- 

 ment (see map, fig. 32), the south-west pass being that 

 through which all the water is now poured out, while each 

 of the others has, by turns, at some former period, been the 

 principal channel of discharge. The narrow tongue of land 

 above alluded to consists simply of two low banks covered 

 with reeds, young willows, and poplars. 

 ^ In appearance these banks answer precisely to those of the 

 river in the alluvial plain (see fig. 31, p. 443) when the inun- 

 dation is at its height, and nothing is seen above water but 

 the upper portions of the banks ; but, in the one cas e, we 

 have on each side a wide expanse of fresh water interrupted 

 only by the tops of the tallest trees which grow in the swamps, 



* 







