As they travelled westwards or south-westwards, day after day, the jagged blue wall resolved itself into towering snow-capped peaks, glittering in the sun and provoking the appellation of "the Mountains of Bright Stones", a name probably given to the Rocky Mountains by the Amerindians, but used in all the earlier French and English maps until the end of the eighteenth century.[15] [Footnote 15: The term Rocky Mountains was probably first officially applied by the American expedition, under Lewis and Clarke, sent out by the United States Government in 1804 to take possession of the coast of Oregon, but it was used twenty or thirty years earlier by British explorers of Western Canada.] On the 12th of January they reached the very foot of the mountains, the slopes of which they saw were thickly covered with magnificent forests of pine and fir--forests, that have since suffered to an appalling extent from annual bush fires, which so far the United States Government seems unable to check.

Here they were to meet with a bitter disappointment.

They were travelling with a very large war party of the Bow Indians for the purpose, if need be, of attacking and routing the Shoshones; but a Shoshone camp at the base of the mountains was found to be deserted, and the Bow Indians jumped to the conclusion that the Shoshones had turned back through the forest unseen, and were now making with all speed for the principal war camp of the Bow Indians, where they would massacre the women and children.
They would listen to no remonstrances from the two Frenchmen, who perforce had also to travel back, either alone or with the Bow Indians, in the direction of their war camp, where the idea of a Shoshone attack was found to be baseless.

Eventually, the two La Verendrye brothers were obliged to make their way to the Missouri River, and abandon any idea of finding a way to the Western Ocean across the Rocky Mountains.
The French pioneers had already heard of the Spaniards in California, and the possibility of getting into touch with them.

They had now discovered, first of all Europeans, the Rocky Mountains--that great snowy range of North America which extends from Robson Peak on the eastern borders of British Columbia to Baldy Peak in New Mexico.
Afterwards the La Verendryes directed their attention more to the opportunities of reaching the Far West through the streams that flowed into the system of Lake Winnipeg, and in this way discovered, in or about 1743, the great River Saskatchewan.