Captain Bonneville led an exploration of the American west while on leave from the US Army from 1832-1834. He was supported financially by John Jacob Astor. Astor's interests were both personal and nationalistic. His fur trade, based at the mouth of the Columbia River, was in direct competition with that of the British and John McCloghlin whose Hudson's Bay Company flourished upriver. Bonneville was sent to explore this contested region.
For his military superiors Bonneville promised to build relations with natives and to provide improved understanding of the new American west on into Oregon. His journals were edited and abridged on his return by Washington Irving as reflected in the heightened drama in the following passages written originally during the late winter of 1834.
Immediately in the route of the travelers lay a high mountain, which they ascended with some difficulty. The prospect from the summit was grand but disheartening. Directly before them towered the loftiest peaks of Imnahah, rising far higher than the elevated ground on which they stood: on the other hand, they were enabled to scan the course of the river, dashing along through deep chasms, between rocks and precipices, until lost in a distant wilderness of mountains, which closed the savage landscape.
They remained for a long time, contemplating with perplexed and anxious eye, this wild congregation of mountain barriers, and seeking to discover some practicable passage. The approach of evening obliged them to give up the task, and to seek some camping ground for the night. Moving briskly forward, and plunging and tossing through a succession of deep snow drifts, they at length reached a valley known among trappers as the "Grand Rond," which they found entirely free from snow.
This is a beautiful and very fertile valley, about twenty miles long and five or six broad; a bright cold stream called the Fourche de glace, or Ice River, runs through it. Its sheltered situation, embosomed in mountains, renders it good pasturing ground in the winter time; when the elk come down to it in great numbers, driven out of the mountains by the snow. The Indians then resort to it to hunt. They likewise come to it in the summer time to dig the camash root, of which it produces immense quantities. When this plant is in blossom, the whole valley is tinted by its blue flowers, and looks like the ocean, when overcast by a cloud .
Up this mountain, therefore, the weary travelers directed their steps: and the ascent, in their present weak and exhausted state, was one of the severest parts of this most painful journey. For two days were they toiling slowly from cliff to cliff, beating at every step a path through the snow for their faltering horses. At length they reached the summit where the snow was blown off; but in descending on the opposite side, they were often plunging through deep drifts, piled in the hollows and ravines.
Their provisions were now exhausted, and they and their horses almost ready to give out with fatigue and hunger; when one afternoon, just as the sun was sinking behind a blue line of distant mountain, they came to the brow of a height from which they beheld the smooth valley of the Imnahah stretched out in smiling verdure below them.
The sight inspired almost a frenzy of delight. Roused to new ardor, they forgot, for a time, their fatigues, and hurried down the mountain, dragging their jaded horses after them, and sometimes compelling them to slide a distance of thirty or forty feet at a time. At length they reached the banks of the Immahah. The young grass was just beginning to sprout, and the whole valley wore an aspect of softness, verdure, and repose, heightened by the contrast of the frightful region from which they had just descended.
Washington Irving, The Adventures of Captain Bonneville, Boston: Twayne Publishers, 1977, pp 166, 169-170.