328 BOTANY AND PALAEONTOLOGY 



form them into humus. Thus this soil does not only want the fertilizing 

 elements of the limestone, but the vegetable mould. The healthy growth 

 of the trees on this kind of soil is easily explained by the softness and per- 

 meability of the rocks. The roots and rootlets penetrate them, and find 

 humidity and food more easily than in the hard limestone. 



The Alluvial formation derived from this sandstone has, like the soil of 

 the ridges, a vegetation somewhat different from the alluvial or bottom 

 land derived from limestone. The alluvial of sandstone has, contrary 

 to that of the ridges, smaller trees than the alluvial of limestone. Its 

 species, which grow close together, are the Birch, the Elm, the Pignut, the 

 Post Oak, the White Oak, the Black Oak, the Chestnut, and the Spanish 

 Oak. On the bottoms derived from limestone, we find especially the 

 Linden, the Buttonwood, the Silver Maple, the Ash-leaved Maple, the Ash, 

 the Honey-Locust, and in the most fertile places the Overcup Oak. The 

 Black, the Red, and the White Oak belong also to this alluvial ground, 

 where they take sometimes an enormous size. 



Many species of Oaks and of Hickory are distributed nearly on every kind 

 of soil, as the White, Red, Black Oaks, with the Black Jack and the Post- 

 Oak, and also appear at far different situations. The Black Jack and the 

 Post-Oak are seen upon the barren rocky ridges, whether sandstone or 

 limestone ; upon barren declivities, clay, swampy ground, generally show- 

 ing sterility. The White, Red, and Black Oaks, especially, cover the 

 slopes also on both formations, descend to the bottoms, more or less indi- 

 cating the value of the soil by the luxuriancy of their size and the deve- 

 lopment of their branches. Nevertheless, we have seen that they thrive 

 well on sandstone, though the soil may be poor for agriculture. It is some- 

 times very difficult to ascertain the geological nature of an alluvial soil. 

 It may pertain to a limestone formation, though it is mixed with sand; it 

 is the amount of lime dissolved in the water which essentially influences 

 the natural distribution of the plants. 



From Benetz Bayou, the limestone and chert are the predominant for- 

 mations all along our road to the western limits of Carroll County. Thus 

 the bottom land of Benetz Bayou appears very fertile. The Overcup Oak 

 grows on this land. It is a species which we see here in Arkansas for the 

 first time, and which is never found but on fertile alluvial soil. Corn 

 especially, sugar, tobacco, and some little cotton, are cultivated, and grow 

 finely in this part of Benton County, which, like the greatest part of 

 Washington County, appears truly favorable for agriculture. If water 

 could be found near the ridges the land would be far more settled than it is 

 now. It is said that even on the rocky and most barren ridges water is 

 generally found in subterranean springs by boring thirty to forty feet deep. 

 I had no opportunity of ascertaining the truth of this assertion. 



The great abundance of grape vines growing in this part of the country, 



