OF ARKANSAS. 335 



Benton, the county seat, is beautifully situated in the middle of these 

 fertile prairies. From this place, or rather from the western borders of 

 the prairies to the western limits of Arkansas, the country is still the pla- 

 teau of limestone, broken by numerous creeks, forming narrow valleys or 

 hills, covered with woods and a fertile soil. The vegetation appears to be 

 the same as that of the hills of Fulton, Marion, &c. But it is well to remark 

 here, that the frost has now killed all the herbaceous plants of the prairies, 

 and that henceforth, in our journey, the botanical observations can be pur- 

 sued but with great disadvantage, and derived only from dry leaves still 

 attached to the trees, or mostly covering the ground. 



GEOLOGICAL NATURE OF THE SOIL AND VEGETATION IN WASHINGTON, 



The true Carboniferous Measures, that is, the sandstone and the shales 

 of the Millstone Grit, with the clay and shales underlying it, are the geo- 

 logical strata from which the elements of the arable soil of these counties 

 is mostly derived. The absence of limestone in the ridges, and the clayey 

 nature of the strata, is at once perceptible in the whitish color of the water 

 of all the creeks which spring from them. In all these counties, the hills 

 or ridges are formed by the Millstone Grit, and consequently their summits 

 are sandy, dry, and sterile, except on somewhat extensive plateaux where 

 water does not find an easy course down the declivities and is retained, 

 moistening the ground by percolating through it. On these flat surfaces 

 only, the soil of the Millstone Grit becomes of sufficient thickness to be 

 arable, and by cultivation is fertile enough. The characteristic trees of this 

 ground are the Yellow Pine, the Spanish Oak, the Black Jack, and Post- 

 Oak, the White, Black, and Red Oaks, the Mockernut, the Chestnut, and 

 the Chincapin, with the Pock Chestnut Oak, the Persimmon, and gene- 

 rally the species of trees and plants which have been mentioned as charac- 

 teristic of the Subcarboniferous Sandstone. 



Near the base of the Millstone Grit, we find thick beds of red shales, 

 covered by flaggy sandstone, and underlaid by beds of clay and black 

 shales, containing sometimes one or two beds of coal. The land extending 

 over these shales is, when flat, transformed into prairies. But, on all the 

 declivities, or where it is cut in hills or undulations by the water-courses, 

 it is covered with a fine growth of trees, viz., the Ped, the Scarlet, and the 

 Black Oak, the Yellow Chestnut Oak, the Laurel Oak, the Sweet Gum, 

 Black Gum, Wild Black Cherry, Shellbark Hickory, and other species, 

 some of which have not been found in the upper country, and with the 

 limestone. The red shales form, by their decomposition, what is called the 

 Ped-upland, and is considered the most fertile soil of this division. As this 



