After having spent nearly five months in this dreary abode, the ice broke up, the boats were repaired and once more got into the river; and other preparations were made for the voyagers to pursue their course towards the sources of the Missouri.
In the afternoon of Sunday, the 7th of April, the arrangements being all completed, the party, consisting of thirty-two persons, once more embarked. They now occupied six small canoes and two large pirogues. The barge was sent down the river, to the United States, with presents of natural curiosities, which had been collected, and with dispatches to the president.
At some distance from Fort Mandan, the land, on each side of the Missouri, after ascending the hills near the water, exhibits the appearance of one fertile and unbroken plain, which extends as far as the eye can reach, without a solitary tree or shrub, except in moist situations, or in the steep declivities of hills. In some parts the plains were on fire; for, every spring, as soon as the ice breaks up in the river, these plains are set on fire by the Indians, for the purpose of driving out and attacking the buffaloes, and other wild animals which inhabit them. Beavers were here very abundant. A herd of antelopes, and the track of a large white bear, were seen in the plain: geese and swans were observed, in great numbers. The musquitoes now began to be very troublesome.
Before the middle of April, the weather became so warm, that, in the day-time, the men worked with no clothes on, except round their waist. On the twelfth, the voyagers reached the mouth of the Little Missouri, where they remained during the day, for the purpose of making celestial observations. This river falls into the Missouri, on its south side, and at the distance of sixteen hundred and ninety-three miles above its confluence with the Mississippi. Its current is strong, and its width a hundred and thirty-four yards; but its greatest depth is only two feet and half. The adjacent country is hilly and irregular; and the soil is, for the most part, a rich dark-coloured loam, intermixed with a small proportion of sand.
On the thirteenth, the voyagers passed the remains of forty-three temporary lodges, which were supposed to have belonged to the Assiniboin Indians. The waters of many of the creeks were found to be so strongly impregnated with mineral salts, that they were not fit to be drunk. On each bank of the Missouri the country presented the appearance of low plains and meadows; bounded, at the distance of a few miles, by broken hills, which end in high, level, and fertile lands: the quantity of timber was increasing. In the timbered-grounds, higher up the river, the voyagers observed a great quantity of old hornets' nests. Many of the hills exhibited a volcanic appearance, furnishing great quantities of lava and pumice stone: of the latter, several pieces were observed floating down the river. In all the copses there were remains of Assiniboin encampments.
On the twentieth, near an Indian camp, the voyagers observed a scaffold, about seven feet high, on which were two sleds, with their harness; and under the scaffold was the body of a female, carefully wrapped in several dressed buffalo-skins. Near it lay a bag, made of buffalo-skin, and containing some articles of apparel, scrapers for dressing hides, some dried roots, plats of sweet grass, and a small quantity of tobacco. These, as well as the body, had probably fallen down by accident, as it is customary to place the dead bodies on scaffolds. At a little distance was the body of a dog, not yet decayed: he had, no doubt, been employed in dragging, in the sled, the body of his mistress, and, according to the Indian usage, had been sacrificed to her.
From the sand-bars in the river, the wind sometimes blew such vast quantities of sand into the air, as to appear like clouds, and even to conceal the opposite bank from view. These clouds of sand floated, like columns of thick smoke, to the distance of many miles; and the particles were so penetrating, that nothing could be kept free from them.
Near the junction of Yellow-stone river with the Missouri, the country was much more woody than it had been in any other part, since the voyagers had passed the Chayenne; and the trees were chiefly of cotton-wood, elm, ash, box, and alder. In the low grounds were rose-bushes, the red-berry, service-berry, red-wood, and other shrubs; and among the bushes on the higher plains, were observed willows, gooseberry-trees, purple currant-trees, and honeysuckles. The sources of Yellow-stone river are said to be in the Rocky Mountains, near those of the Missouri and the Platte; and this river is navigable, in canoes, almost to its head.
Near the junction of the Yellow-stone and Missouri rivers, there is a high plain, which extends three miles in width, and seven or eight miles in length; and which Captain Lewis says might be rendered a very advantageous station for a trading establishment.
Beyond this place, the hills were rough and high, and almost overhung the river. As the voyagers advanced, the low grounds were fertile and extensive, with but little timber, and that cotton-wood. On the 3d of May, they reached the mouth of a river, which; from the unusual number of porcupines that were seen near it, they called Porcupine river. For several days after this, they continued their progress without much interruption. In many places the river was, at least, half a mile wide. During their excursions on the shore, in pursuit of food, they encountered many perils in shooting at bears. Some of these were of vast size and strength: one of them weighed nearly six hundred pounds, and measured eight feet seven inches and a half, from the nose to the extremity of the hind feet.