Miscellaneous Geological Topics, &fc. 49 



Art. X. — Miscellaneous ' Geological Topics relating to the loiver 

 pari of the vale of the Mississippi y alluvion by rain; up filling 

 and extension of valleys ; subsidence of the sea ; original vale of 

 the river ivith its wings and present channel. — From unpublished 

 MSS. on the Theory of the Earth; by Dr. Rush Nutt, of 

 Rodney, Mississippi. 



That tiie ocean once rolled Its waves over the present Delta of 

 the Mississippi does not admit of a doubt. We will first consider the 

 tract of country, from Vicksburgh to Baton Rouge, whose width is 

 between ten and fifteen miles from the present boundary of the bluff. 



SKETCH OF THE COUNTRY. 



The unevenness of the face of this district will at once strike the 

 traveller with surprise. It is a country cut to pieces by broad ravines; 

 and notwithstanding the narrowness of the ridges, they are much dis- 

 figured by excavations, running into their sides. The general direc- 

 tion of the principal ridges is westerly, intersecting the Mississippi at 

 right angles, and they are gradually depressed, as they run from the 

 limits of the district now under consideration, until they are cut off by 

 the vale. 



Most of the bluffs are from one to two hundred feet in height. By 

 observing their descent, which is often gradual, when receding from 

 the bluff to the limit of the territory we are now describing, it would 

 appear that, did the ridges run upon a declivity similar to that Vv'hich 

 they formerly had, they would extend at least ten or fifteen miles 

 farther than they now do, in a similar course. We shall then sup- 

 pose, that prior to the existence of the present river, these bluffs were 

 continued and terminated by a gentle declivity; being met by a slight 

 subsidence on the other side, which was an extensive ravine, that 

 was afterwards to become the present vale ; thus they gradually en- 

 croached upon the basin, and finally succeeded in driving out the 

 waters of the. gulf, which we shall consider as the Natches basin. 



COMPOSITION OF THE STRATA. 



In proof of the correctness of our position, we shall appeal to the 

 fact, of the presence of molluscous testacea, which are found to be 

 very regularly and generally dispersed from within five feet of the 

 present surface down to the sand, which formed the downs and beach 

 of the ocean itself. The first fi.)ot of soil we shall call vegetable 



Vol. XXIIl.— No. 1. 7 



