For many successive days the voyagers continued to see Indians every day. They had occasionally wet and unpleasant weather. In one place they saw, on the bank of the river, a great number of goats; and, soon afterwards, large flocks of these animals were driven into the river by a party of Indians, who gradually lined the shore, so as to prevent their escape, and fired on them, and beat them down with clubs, with so much success, that, in a short time, they killed more than fifty. Many buffaloes, elks, and deer were seen; and a great number of snakes.
On Thursday the 18th, they passed the mouth of _Le Boulet_, or _Cannon-ball river_, the channel of which is about one hundred and forty yards wide. This stream, (which is indebted for its name to a great number of large stones, that are perfectly round and lie scattered about the shore and on the eminences above,) rises in the Black Mountains, and falls into the Missouri on the south. Great numbers of goats were observed to cross the river, and direct their course towards the west. The country, in general, was level and fine, with broken, short, high grounds, low timbered mounds near the river, and a range of rugged hills at a distance. The low grounds had here much more timber than had been observed lower down the river. So numerous are wild animals in this part of the country, that the voyagers counted, at a single view, fifty-two herds of buffaloes, and three of elks.
On the 20th the weather was so cold, that the rain which fell froze on the ground; and, in the course of the night, the ground was covered with snow. A Ricara chief told Captain Lewis that, at some distance up one of the rivers, there was a large rock which was held in great veneration by the Indians, and was often consulted by them, as to their own, or their nations' destinies; all of which they imagine they are able to discern, in some rude figures or paintings, with which it is covered.
The voyagers passed, on each side of the river, the ruins of several villages of _Mandan Indians_; and, on an island of the river, they found a Mandan chief, who, with some of his men, was on a hunting excursion. As they proceeded, several parties of Mandans, both on foot and on horseback, approached the shore to view them. The vessels here got aground several times, among the sand-bars and rocks. In this part of their voyage they saw two Europeans, belonging to the Hudson's Bay company. These men had arrived about nine days before, to trade for horses and buffalo robes.