At no great distance to the east of our camp was one of these peculiar hills above mentioned. In visiting it we crossed a ridge of sandstone, about three hundred feet in height, with strata inclined to the west. To this succeeds a valley, about one mile wide, having a scanty growth of pine and oak. The ascent of the hill is steep and rugged. Horizontal strata of sandstone and coarse conglomerate are exposed on its sides, and the summit is capped by thin stratum of compact sandstone, surmounted by a bed of greenstone trap, or trappea porphyry. The loose and splintery fragments of this rock sometimes cover the surface, making a clinking noise under the feet, like fragments of pottery. The summit of this hill is of an oval form, about eight hundred yards in length and five hundred in breadth. Its surface is undulating, and is terminated on all sides by perpendicular precipices. The elevation of the hill is about one thousand feet, and the height of the perpendicular precipices, from the summit of the _débris_ to the top of hill, about fifty. From the top of this hill, the high peak mentioned by Captain Pike, was discovered, and its bearing found to be S. 50. W. Several of the party ascended Defile creek until they arrived at the mountains, into which they penetrated as far as was found practicable. As they travelled along the bed of this, they found the several rock formations beautifully exposed, and in the following order. Commencing from the alluvial of the plain on the east, they saw: First, Horizontal sandstone, embracing extensive {201} beds of coarse conglomeratic, and commonly of a light gray or reddish yellow colour. Second, Fine compact gray sandstone, containing a few impressions of organized remains, resembling those in the sandstones of coal formations. This rock is inclined at an angle of near twenty degrees towards the west. It forms continuous ranges of hills, not difficult of ascent from the east, but their western declivities are abrupt and precipitous. Third, Lofty and detached columns of sandstone, of a reddish or deep brown colour. These are irregularly scattered throughout a narrow untimbered valley. Some of them rise probably three hundred feet above the common level of the plain, and are so steep on all sides as to preclude the possibility of ascent. Others are accessible at some points, and one of these we ascended. Sketches of these singular rocks have been preserved both by Mr. Peale and Mr. Seymour.