With the change in the geological formation on leaving Fort Laramie, the whole face of the country has entirely altered its appearance. Eastward of that meridian, the principal objects which strike the eye of a traveler are the absence of timber, and the immense expanse of prairie, covered with the verdure of rich grasses, and highly adapted for pasturage. Wherever they are not disturbed by the vicinity of man, large herds of buffalo give animation to this country. Westward of Laramie river, the region is sandy, and apparently sterile; and the place of the grass is usurped by the _artemisia_ and other odoriferous plants, to whose growth the sandy soil and dry air of this elevated region seem highly favorable.
One of the prominent characteristics in the face of the country is the extraordinary abundance of the _artemisias_. They grow everywhere--on the hills, and over the river bottoms, in tough, twisted, wiry clumps; and, wherever the beaten track was left, they rendered the progress of the carts rough and slow. As the country increased in elevation on our advance to the west, they increased in size; and the whole air is strongly impregnated and saturated with the odor of camphor and spirits of turpentine which belongs to this plant. This climate has been found very favorable to the restoration of health, particularly in cases of consumption; and possibly the respiration of air so highly impregnated with aromatic plants may have some influence.
Our dried meat had given out, and we began to be in want of food; but one of the hunters killed an antelope this evening, which afforded some relief, although it did not go far among so many hungry men. At eight o'clock at night, after a march of twenty-seven miles, we reached our proposed encampment on the _Fer-à-Cheval_, or Horse-shoe creek. Here we found good grass, with a great quantity of _prele_, which furnished good food for our tired animals. This creek is well timbered, principally with _liard amere_, and, with the exception of Deer creek, which we had not yet reached, is the largest affluent of the right bank between Laramie and the mouth of the Sweet Water.
23d.--The present year had been one of unparalleled drought, and throughout the country the water had been almost dried up. By availing themselves of the annual rise, the traders had invariably succeeded in carrying their furs to the Missouri; but this season, as has already been mentioned, on both forks of the Platte they had entirely failed. The greater number of the springs, and many of the streams, which made halting places for the _voyageurs_, had been dried up. Everywhere the soil looked parched and burnt, the scanty yellow grass crisped under the foot, and even the hardest plants were destroyed by want of moisture. I think it necessary to mention this fact, because to the rapid evaporation in such an elevated region, nearly five thousand feet above the sea, almost wholly unprotected by timber, should be attributed much of the sterile appearance of the country, in the destruction of vegetation, and the numerous saline efflorescences which covered the ground. Such I afterwards found to be the case.