The woody fibre of these furnished the only fuel available for early overland emigrants to the Pacific.
The character of this country now changed considerably as the explorers turned to the northward, in their crooked course, with the river.

On the twenty-fifth of May the journal records this:-- "The country on each side is high, broken, and rocky; the rock being either a soft brown sandstone, covered with a thin stratum of limestone, or else a hard, black, rugged granite, both usually in horizontal strata, and the sand-rock overlaying the other.

Salts and quartz, as well as some coal and pumice-stone, still appear.

The bars of the river are composed principally of gravel; the river low grounds are narrow, and afford scarcely any timber; nor is there much pine on the hills.

The buffalo have now become scarce; we saw a polecat (skunk) this evening, which was the first for several days; in the course of the day we also saw several herds of the bighorned animals among the steep cliffs on the north, and killed several of them." The bighorned animals, the first of which were killed here, were sometimes called "Rocky Mountain sheep." But sheep they were not, bearing hair and not wool.