{13} The loose soft sands of the river-bed yielding to our horses feet, made the travelling extremely laborious; and the intense reflection of the rays of the sun almost deprived us of the use of our eyes. Mr. Peale's horse soon became unable to proceed at an equal pace with the remainder of the party; but as no suitable place for encampment appeared, he dismounted, and by great exertions was able to urge his animal along in the rear. The travelling in the bed of the river became so extremely inconvenient, that we resolved upon attempting to penetrate the thick woods of the bottom, and ascend to the open plains. We found, however, the woods so thick, and so interlined with scandent species of smilax cissus, and other climbing vines, as greatly to retard our progress, and we were soon induced to wish ourselves again upon the naked sands. Notwithstanding the annoyance they gave us, we took a pleasure in observing the three American species of cissus growing almost side by side. The cissus quinquefolia,[74] the common woodbine, cultivated as an ornament about yards and summer-houses, grows here to an enormous size, and, as well as the cissus hederacea, seems to prefer climbing on elms. The remaining species, the cissus bipinnata, is a smaller plant, and, though much branched, is rarely scandent. All of them abound in ripe fruit, which, notwithstanding its external resemblance and its close affinity to the grape, is nauseous to the taste, and does not appear to be sought with avidity even by the bears. In ascending the hills, we found them based upon a variety of sandstone, unlike the red rock of the salt formation, to which we had been so long accustomed. With this change a corresponding change takes place in the conformation of the surface and the general aspect of the country. The hills are higher and more abrupt, the forests more extensive, the streams of water more copious {14} and more serpentine in their direction; in other words, we here begin to recognize the features of a mountainous region. The sandstone which appears in the beds of the streams, and the sides of the hills, is coarse and hard, of a dark gray colour, and a horizontally laminated structure. It is deeply covered with a soil of considerable fertility, sustaining heavy forests of oak. Among these trees the upland white oak is common, but is of rather diminutive size, and often hollow. In a tree of this description we observed, as we passed, the habitation of a swarm of bees, and as it was not convenient at that time to stop, we fixed a mark upon it, and proceeded to make the best of our way towards the river. On descending the hills, we found the valley of the river much contracted in width, and the bed itself occupying less space by half than where we had left it above.