78 Sketches of the Geology, fyc. of Alabama. 



elevation cannot be great, for waggons which pass from the 

 valley to the market towns on the Alabama, carry as heavy 

 loads as those that pass through only a level country. The 

 engineer also reported that a canal might easily be made 

 around the rapids, which would not probably be the case if 

 there were mountains crossing the river. From these facts, 

 and from the nature of the country which I saw, some twen- 

 ty miles west, I conclude that the primitive mountains termi- 

 nate east of the Coosa river. From the junction of the 

 Coosa and Tallapoosa, the Alabama river pursues a westerly 

 course one hundred miles, or about fifty, in a direct line to 

 Cahawba. The banks are very high, more than fifty feet 

 above low water, to which height the river often rises in the 

 winter. The banks when they present a recent surface, ex- 

 hibit a beautiful appearance, striped with alternate layers of 

 gravel and different colored clays. The clays commence 

 about twenty feet above low water. The layers are of dif- 

 ferent thickness from one inch to several feet, and of various 

 colors, from red and deep blue to a delicate white. The 

 white is sometimes so pure, that the people use the substance 

 for paint. The gravel stones in this region are mostly 

 very small. Two specimens resembling flint, I picked up 

 among the pebbles. Beautiful shells, of which I send you 

 specimens, are found particularly in the islands of the river, 

 and some which I saw are large and exhibit a most mag- 

 nificent play of colors. I intended to have procured some 

 of the finest, but owing to ill health, I was prevented. The 

 specimen of limestone is from the prairies nearly west from 

 Cahawba. Much shell limestone is found in the region some 

 distance south. Salt springs are found about half the distance 

 from Cahawba to Mobile, from which much salt of a superi- 

 or quality is made. Leaving the Alabama river in the cen- 

 tre of the state, and proceeding north towards Huntsville, 

 the country is somewhat hilly with few rocks to be seen for 

 forty-five miles, where is a hill of large boulders of granite, 

 but none in place. The first rock in place is seen at Wil- 

 son's Hill fifteen miles farther north. Here we find the com- 

 mon secondary gray limestone. For the next seventy miles, 

 the country is mountainous or rather hilly, with elevations of 

 three or four hundred feet above the valleys. The lime- 

 stone continues associated with sandstone of different shades 

 of red and gray. For the next sixty miles to the Tennessee 

 river, the country is level, but very elevated ; rock, almost 



