The sandstone near the springs is hard, though rather coarse, and of a dark gray or brownish yellow colour. In ascending the Arkansa on the ensuing morning, we found the rock to become more inclined, and of a redder colour, as we approached the primitive, until, at about half a mile from the springs, it is succeeded by the almost perpendicular gneiss rock, which appears here at the base of the first range of the mountains. We have noticed that this particular spot is designated, in the language of hunters, as "the place where the Arkansa _comes out_ of the mountains;" and it must be acknowledged, the expression is not entirely inapplicable. The river pours with great impetuosity and violence through a deep and narrow fissure in the gneiss rock, which rises so abruptly on both sides to such a height, as to oppose an impassable barrier to all further progress. According to the delineation of Pike's route, upon the map which accompanies his work, he must have entered the mountains at this place; but no corroboration can be derived from his journal. It appears almost incredible that he should have passed by this route, and have neglected to mention the extreme difficulty which must have attended the undertaking. The detached party returned to the encampment of the main body on the 18th. The immediate valley of the Arkansa, near the mountains, is bounded by high cliffs of inclined sandstone. At a short distance below these disappear, and a sloping margin of alluvial earth extends on each side to the distance of several miles. Somewhat farther down horizontal sandstone appears, confining {234} the valley to a very narrow space, and bounding it within perpendicular precipices on each side. Seven miles from the mountains, on the left hand side of the Arkansa, is a remarkable mass of sandstone rocks, resembling a large pile of architectural ruins. From this point the bearing of James's Peak[15] was found to be due north. The Arkansa valley, between our encampment of the 16th and the mountains, a distance of about thirty miles, has a meagre and gravelly soil, sustaining a growth of small cotton-wood trees, rushes, and coarse grass: above the rocky bluffs, on each side, spreads a dreary expanse of almost naked sand, intermixed with clay enough to prevent its drifting with the wind, but not enough to give it fertility. It is arid and sterile, bearing only a few dwarfish cedars, and must for ever remain desolate.