About all the woodless parts of the mountain, and particularly on the summit, numerous tracks were seen, resembling those of the common deer, but most probably have been those of the animal called the big horn. The skulls and horns of these animals we had repeatedly seen near the licks and saline springs at the foot of the mountain, but they are known to resort principally about the most elevated and inaccessible places. The party remained on the summit only about half an hour; in this time the mercury fell to 42°, the thermometer hanging against the side of a rock, which in all the early part of the day had been exposed to the direct rays of the sun. At the encampment of the main body in the plains, a corresponding thermometer stood in the middle of the day at 96°, and did not fall below 80° until a late hour in the evening. Great uniformity was observed in the character of the rock about all the upper part of the mountain. {222} It is a compact, indestructible aggregate of quartz and felspar, with a little hornblende, in very small particles. Its fracture is fine, granular, or even; and the rock exhibits a tendency to divide when broken into long, somewhat splintery fragments. It is of a yellowish brown colour, which does not perceptibly change by long exposure to the air. It is undoubtedly owing to the close texture and the impenetrable firmness of this rock that so few lichens are found upon it. For the same reason it is little subject to disintegration by the action of frost. It is not improbable that the splintery fragments, which occur in such quantities on all the higher parts of the peak, may owe their present form to the agency of lightning. No other cause seems adequate to the production of so great an effect. Near the summit some large detached crystals of felspar, of a pea-green colour, were collected; also large fragments of transparent, white and smoky quartz, and an aggregate of opaque white quartz, with crystals of hornblende. At about five in the afternoon the party began to descend, and a little before sunset arrived at the commencement of the timber; but before we reached the small stream at the bottom of the first descent, we perceived we had missed our way. It was now become so dark as to render an attempt to proceed extremely hazardous; and as the only alternative, we kindled a fire, and laid ourselves down upon the first spot of level ground we could find. We had neither provisions nor blankets; and our clothing was by no means suitable for passing the night in so bleak and inhospitable a situation. We could not, however, proceed without imminent danger from precipices; and by the aid of a good fire, and no ordinary degree of fatigue, found ourselves able to sleep during a greater part of the night.