nightfall we descended to a little stream, on which we encamped, about two
miles from the Sweet Water. Here had recently been a very large camp of
the Snake and Crow Indians; and some large poles lying about afforded the
means of pitching a tent, and making other places of shelter. Our fires
to-night were made principally of the dry branches of the artemisia, which
covered the slopes. It burns quickly, and with a clear oily flame, and
makes a hot fire. The hills here are composed of hard, compact mica slate,
with veins of quartz.

7th.--We left our encampment with the rising sun. As we rose from the bed
of the creek, the _snow_ line of the mountains stretched gradually
before us, the white peaks glittering in the sun. They had been hidden in
the dark weather of the last few days, and it had been _snowing_ on
them, while it _rained_ in the plains. We crossed a ridge, and again
struck the Sweet Water--here a beautiful, swift stream, with a more open
valley, timbered with beech and cottonwood. It now began to lose itself in
the many small forks which make its head; and we continued up the main
stream until near noon, when we left it a few miles, to make our noon halt
on a small creek among the hills, from which the stream issues by a small
opening. Within was a beautiful grassy spot, covered with an open grove of
large beech-trees, among which I found several plants that I had not
previously seen.

The afternoon was cloudy, with squalls of rain; but the weather became
fine at sunset, when we again encamped on the Sweet Water, within a few
miles of the SOUTH PASS. The country over which we have passed to-day
consists principally of the compact mica slate, which crops out on all
ridges, making the uplands very rocky and slaty. In the escarpments which
border the creeks, it is seen alternating with a light-colored granite, at
an inclination of 45 deg.; the beds varying in thickness from two or three