CHAP. XXXIV.] UPRAISED TERRACES. 1;3 



the same age as No. 2, rising from 50 to 200 feet above the 

 level of the sea, constitutes the entire bluffs, forming a table-land 

 like that represented at d, e. Similar deposits, #, c (fig. 10), 

 recur in Louisiana, on the western side of the great valley ; but 

 they are not, I am informed, denuded so as to present a steep 

 bluff at a. They rest equally on Eocene strata, /(No. 3). 



From what has been said of the species of shells contained in 

 the loam, d, e, at Natchez, and in other localities, from the 

 remains also of associated terrestrial animals, and from the 

 buried trees of Port Hudson, we have inferred that these deposits 

 (No. 2), are the monuments of an ancient alluvial plain, of an 

 age long anterior to that through which the Mississippi now 



Fig. 10. 



VALLEY OF THE MISSISSIPPI. 

 Louisiana. c 



1. Alluvium. 2. Loess. 3. /. Eocene. 4. Cretaceous. 



flows, which was inhabited by land and fresh-water mollusca 

 agreeing with those now existing, and by quadrupeds now for 

 the most part extinct. 



In my former &quot; Travels in North America,&quot; I described some 

 ancient terraces of gravel, sand, and loam, occurring every where 

 in the valley of the Ohio, and gave a section of them as they are 

 seen at Cincinnati.* I pointed out that the included fossil 

 shells demonstrate the fluviatile and modem origin of the 

 deposits, and suggested that their present position could only be 

 explained by supposing, first, a gradual sinking down of the land 

 after the original excavation of the valley, during which period 

 the gravel and sand were thrown down, and then an upheaval 

 of the same valley, when the river cut deep channels through 

 the fresh-water beds.f Certain swamp formations observable in 



* Travels in North America, fig. 9, vol. ii. p. 59, chap. xvii. 

 t The second terrace (c, fig. 9, ibid.) at Cincinnati, may imply a second 

 oscillation. 



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