Many of the tributary streams of Snake River, rival it in the wildness and picturesqueness of their scenery.  That called the Bruneau; is particularly cited.  It runs through a tremendous chasm, rather than a valley, extending upwards of a hundred and fifty miles.  You come upon it on a sudden, in traversing a level plain.  It seems as if you could throw a stone across from cliff to cliff; yet, the valley is near two thousand feet deep:  so that the river looks like an inconsiderable stream.  Basaltic rocks rise perpendicularly, so that it is impossible to get from the plain to the water, or from the river margin to the plain.  The current is bright and limpid.  Hot springs are found on the borders of this river.  One bursts out of the cliffs forty feet above the river, in a stream sufficient to turn a mill, and sends up a cloud of vapor.

We find a characteristic picture of this volcanic region of mountains and streams, furnished by the journal of Mr. Wyeth, which lies before us; who ascended a peak in the neighborhood we are describing.  From this summit, the country, he says, appears an indescribable chaos; the tops of the hills exhibit the same strata as far as the eye can reach; and appear to have once formed the level of the country; and the valleys to be formed by the sinking of the earth, rather than the rising of the hills.  Through the deep cracks and chasms thus formed, the rivers and brooks make their way, which renders it difficult to follow them.  All these basaltic channels are called cut rocks by the trappers.  Many of the mountain streams disappear in the plains; either absorbed by their thirsty soil, and by the porous surface of the lava, or swallowed up in gulfs and chasms.

On the 12th of January (1834), Captain Bonneville reached Powder River; much the largest stream that he had seen since leaving the Portneuf.  He struck it about three miles above its entrance into Snake River.  Here he found himself above the lower narrows and defiles of the latter river, and in an open and level country.  The natives now made their appearance in considerable numbers, and evinced the most insatiable curiosity respecting the white men; sitting in groups for hours together, exposed to the bleakest winds, merely for the pleasure of gazing upon the strangers, and watching every movement.  These are of that branch of the great Snake tribe called Shoshokoes, or Root Diggers, from their subsisting, in a great measure, on the roots of the earth; though they likewise take fish in great quantities, and hunt, in a small way.  They are, in general, very poor; destitute of most of the comforts of life, and extremely indolent:  but a mild, inoffensive race.  They differ, in many respects, from the other branch of the Snake tribe, the Shoshonies; who possess horses, are more roving and adventurous, and hunt the buffalo.

On the following day, as Captain Bonneville approached the mouth of Powder River, he discovered at least a hundred families of these Diggers, as they are familiarly called, assembled in one place.  The women and children kept at a distance, perched among the rocks and cliffs; their eager curiosity being somewhat dashed with fear.  From their elevated posts, they scrutinized the strangers with the most intense earnestness; regarding them with almost as much awe as if they had been beings of a supernatural order.