The barrens then are natural meadows, covered with tall coarse grass, varying in extent and figure, with here and there a piece of elevated ground, decked with a cluster of trees; add to this, a reddish stream running through ground but little lower than the surrounding plain, and you have the picture complete. There are large districts of this description in Kentucky, Tennessee, and Alabama; they are common in Illinois and Missouri, and are found more or less over the whole valley of the Mississippi. This region and the bushy prairies, abound in those singular cavities called sink-holes, which are generally in the shape of inverted cones, from ten to seventy feet in depth, and at the top from sixty to three hundred feet in circumference. Willows and other aquatic vegetables grow at the sides and bottom. There is little doubt that these cavities are caused by running waters, which find their way through the limestone cavities beneath the upper stratum of the soil. The remaining surface is that of the prairies, and this is by far the most extensive. These may be classed under three general divisions, though they have great diversity of aspect; the heathy, or bushy; the alluvial, or wet; and the dry, or rolling prairies. The bushy prairies seem to be intermediate between the barrens and the alluvial prairies. They have springs, abound in bushes and shrubs, with grape vines, and in the summer with a great variety of flowers; the bushes are often overtopped with the common hop vine. Prairies of this description are very common in Illinois, Mississippi, and Indiana, and they occur among the other prairies to a considerable distance towards the Chippewayan Mountains. The dry prairies are for the most part without springs, and destitute of all vegetation except weeds, flowering plants, and grass. To the sight they are nearly level, but their inclination is proved by the quick motion of the water courses. This class of prairies is by far the most extensive. Here are the haunts of the buffaloes, and here the traveller may wander for days without wood or water, and the horizon on every side sinking to contact with the grass.