The Shoshonee woman took leave of us here, expecting to find some of her relations at Bridger's fort, which is only a mile or two distant, on a fork of this stream. In the evening we encamped on a salt creek, about fifteen feet wide, having to-day traveled 32 miles.
I obtained an emersion of the first satellite under favorable circumstances, the night being still and clear.
One of our mules died here, and in this portion of our journey we lost six or seven of our animals. The grass which the country had lately afforded was very poor and insufficient; and animals which have been accustomed to grain become soon weak and unable to labor, when reduced to no other nourishment than grass. The American horses (as those are usually called which are brought to this country from the States) are not of any serviceable value until after they have remained a winter in the country, and become accustomed to live entirely on grass.
19th.--Desirous to avoid every delay not absolutely necessary, I sent on Carson in advance to Fort Hall this morning, to make arrangements for a small supply of provisions. A few miles from our encampment, the road entered a high ridge, which the trappers called the "little mountain," connecting the Utah with the Wind River chain; and in one of the hills near which we passed I remarked strata of a conglomerate formation, fragments of which were scattered over the surface. We crossed a ridge of this conglomerate, the road passing near a grove of low cedar, and descending upon one of the heads of Ham's fork, called Muddy, where we made our mid-day halt. In the river hills at this place, I discovered strata of fossiliferous rock, having an _oolitic structure_, which, in connection with the neighboring strata, authorize us to believe that here, on the west side of the Rocky mountains, we find repeated the modern formations of Great Britain and Europe, which have hitherto been wanting to complete the system of North American geology.
In the afternoon we continued our road, and searching among the hills a few miles up the stream, and on the same bank, I discovered, among the alternate beds of coal and clay, a stratum of white indurated clay, containing very clear and beautiful impressions of vegetable remains. This was the most interesting fossil locality I had met in the country, and I deeply regretted that time did not permit me to remain a day or two in the vicinity; but I could not anticipate the delays to which I might be exposed in the course of our journey--or, rather, I knew that they were many and inevitable; and after remaining here only about an hour, I hurried off, loaded with as many specimens as I could conveniently carry.