8th.--We continued to-day to travel up the Platte: the morning pleasant, with a prospect of fairer weather. During the forenoon our way lay over a more broken country, with a gravelly and sandy surface; although the immediate bottom of the river was a good soil, of a dark and sandy mould, resting upon a stratum of large pebbles, or rolled stones, as at Laramie fork. On our right, and apparently very near, but probably 8 or 10 miles distant, and two or three thousand feet above us, ran the first range of the mountains, like a dark corniced line, in clear contrast with the great snowy chain which, immediately beyond, rose glittering five thousand feet above them. We caught this morning a view of Pike's peak; but it appeared for a moment only, as clouds rose early over the mountains, and shrouded them in mist and rain all the day. In the first range were visible, as at the Red Buttes on the North fork, very lofty escarpments of red rock. While traveling through this region, I remarked that always in the morning the lofty peaks were visible and bright, but very soon small white clouds began to settle around them--brewing thicker and thicker as the day advanced, until the afternoon, when the thunder began to roll; and invariably at evening we had more or less of a thunder storm. At 11 o'clock, and 21 miles from St. Vrain's fort, we reached a point in this southern fork of the Platte, where the stream is divided into three forks; two of these (one of them being much the largest) issuing directly from the mountains on the west, and forming, with the eastern-most branch, a river of the plains. The elevation of this point is about 5,500 feet above the sea; this river falling 2,800 feet in a distance of 316 miles, to its junction with the North fork of the Platte. In this estimate, the elevation of the junction is assumed as given by our barometrical observations in 1842. On the easternmost branch, up which we took our way, we first came among the pines growing on the top of a very high bank, and where we halted on it to noon; quaking asp (_populus tremuloides_) was mixed with the cottonwood, and there were excellent grass and rushes for the animals.
During the morning there occurred many beautiful flowers, which we had not hitherto met. Among them, the common blue flowering flax made its first appearance; and a tall and handsome species of _gilia_, with slender scarlet flowers, which appeared yesterday for the first time, was very frequent to-day.