"7th.--At about 10 o'clock, the party arrived; and we continued our journey through a country which offered but little to interest the traveler. The soil was much more sandy than in the valley below the confluence of the forks, and the face of the country no longer presented the refreshing green which had hitherto characterized it. The rich grass was now found only in dispersed spots, on low grounds, and on the bottom land of the streams. A long drought, joined to extreme heat, had so parched up the upper prairies, that they were in many places bald, or covered only with a thin growth of yellow and poor grass. The nature of the soil renders it extremely susceptible to the vicissitudes of the climate. Between the forks, and from their junction to the Black hills, the formation consists of marl and a soft earthy limestone, with granitic sandstone. Such a formation cannot give rise to a sterile soil; and, on our return in September, when the country had been watered by frequent rains, the valley of the Platte looked like a garden; so rich was the verdure of the grasses, and so luxuriant the bloom of abundant flowers. The wild sage begins to make its appearance, and timber is so scarce that we generally made our fires of the _bois de vache_. With the exception of now and then an isolated tree or two, standing like a lighthouse on the river bank, there is none to be seen.