326 BOTANY AND PALEONTOLOGY 



Locust, — grow along the creeks which meander in their middle. The soil 

 is, in its natural state, mostly covered with the great Composite of the 

 prairies and the hard grasses, species of Beard-grass and Broom-corn. 



The prairies of the third class are extensively formed in Arkansas on the 

 Tertiary or Alluvial land bordering some rivers of the South, especially Eed 

 River. Our exploration did not extend to that part of the State. It is 

 very probable that these prairies have been formed in the same manner 

 and by the same agency as those of the other sections. From the catalogue 

 of Mr. Nuttall, who explored these plains, their plants appear somewhat 

 different from those of the other prairies. They rather bear the character 

 of a "Western Flora, or of the Flora of the plains extending toward Mexico. 



GEOLOGICAL NATURE OF THE SOIL AND VEGETATION IN FULTON, MARION, 



The characteristic formations of all these counties are: the Silurian 

 either cherty or compact limestone, with some strata of sandstone, and the 

 Subcarboniferous cherty or compact limestone, with alternating beds of 

 shales or of sandstone. The geographical character of the country is that 

 of a plateau divided into a series of successive ridges by numerous clear 

 creeks, mostly running southward or northward to White River, or by 

 some of its forks. When these ridges are composed of compact, hard mag- 

 nesian limestone, they are nearly barren, the top only being covered with 

 a scanty vegetation. When the limestone is somewhat porous and reten- 

 tive of water, the flat surfaces of the tops, or even the declivities of the 

 ridges, are covered with prairies. Where the rock is soft and easily dis- 

 aggregated it is mostly covered with trees. 



In the eastern part of Fulton County, the ridges, mostly of cherty lime- 

 stone, are rocky, but, nevertheless, covered with trees of small size : the 

 Mockernut Hickory, the Black Jack and the Post Oak. The top of these 

 ridges is clothed by a luxuriant vegetation of grasses and numerous species 

 of herbaceous plants, thus furnishing a good and abundant pasture for 

 cattle, especially for sheep. A great number of them could be raised in 

 this country. The slopes are gentle and covered with humus, or with a 

 soil of greater fertility than might be supposed from the stunted growth of 

 the trees. It is the Hickory or Mulatto-barren soil, soft, permeable, of a 

 grayish color, producing abundant crops of corn (fifty to sixty bushels to 

 the acre in favorable situations), and especially wheat (twenty-five to thirty- 

 five bushels an acre). The trees naturally growing on this kind of ground 

 are scattered or distant, of the same species as those of the ridges, with the 

 Red, the Black, and the White Oak. The Spanish Oak is also mixed with 

 this vegetation, but it is scarce, and of the remarkable variety Quercus 



