When the Missouri turned southward the explorers came to many steep rapids, around which the canoes had to be carried, which made traveling slow. Often the banks were so steep and the mud so thick that the men were obliged to take off their moccasins, and much of the time they were up to their arms in the cold water of the river. But there was a great deal to charm the eye in the opening spring, even in that bare country. Lewis found places near the river filled with choke-cherries, yellow currants, wild roses, and prickly pears in full bloom. In the distance the mountains, rising in long greenish-blue chains, the tops covered with snow, invited the travelers to find what lay on the other side of their ridges.
On June 3d they reached a place where the river divided into two wide streams, and it became very important to decide which of the two was the one that the Indians called the Ahmateahza, or Missouri, which they had said approached very near to the Columbia River. Lewis knew that the success of his expedition depended largely upon choosing the right stream, because if, after they had ascended the Rocky Mountains beyond, they should find that the river they had taken did not bring them near the Columbia, they would have to return, and thereby would lose a large part of the summer, which was the only season when they could travel. For this reason he decided to send out two exploring parties. He himself made a two days' march up the north branch, and deciding that this was not the Missouri, he named it Maria's River. As they came back they had to walk along high cliffs, and at one steep point Captain Lewis slipped, and, if he had not been able to catch himself with his mountain stick, would have been thrown into the river. He had just reached a point of safety when he heard a man behind him call out, "Good God, captain, what shall I do?" Turning instantly he found that his companion had lost his footing on the narrow pass, and had slipped down to the very edge of the precipice, where he lay with his right arm and leg over the cliff, while with the other arm and leg he was trying to keep from slipping over. Lewis saw the danger, but calmly told the other to take his knife from his belt with his right hand, and dig a hole in the side of the bluff in which to stick his foot. With great presence of mind the man did this, and getting a foothold, raised himself on his knees. Lewis then told him to take off his moccasins, and crawl forward on his hands and knees, his knife in one hand and his rifle in the other. In this manner the man regained a secure place on the cliff.
Captain Lewis considered that this method of traveling was too dangerous, and he ordered the rest of the party to wade the river at the foot of the bluff, where the water was only breast-high. This adventure taught them the danger of crossing the slippery heights above the stream, but as the plains were broken by ravines almost as difficult to pass, they kept on down the river, sometimes wading in the mud of the low grounds, sometimes in the water, but when that became too deep, cutting footholds in the river bank with their knives. On that particular day they traveled through rain, mud, and water for eighteen miles, and at night camped in a deserted Indian lodge built of sticks. Here they cooked part of the six deer they had killed in the day's traveling, and slept on willow boughs they piled inside the lodge.
Many of the party thought that the north fork was the Missouri River, but Lewis and Clark were both convinced that the south fork was the real Missouri. They therefore hid their heaviest boat and all the supplies they could spare, and prepared to push on with as little burden as possible. A few days later Lewis was proved to be right in his judgment of the south fork, for on June 13th he came to the Great Falls of the Missouri. The grandeur of the falls made a tremendous impression on them all. The river, three hundred yards wide, was shut in by steep cliffs, and for ninety yards from the left cliff the water fell in a smooth sheet over a precipice of eighty feet. The rest of the river shot forward with greater force, and, being broken by projecting rocks, sent clouds of foam into the air. As the water struck the basin below the falls it beat furiously against the ledge of rocks that extended across the river, and Lewis found that for three miles below the stream was one line of rapids and cascades, overhung by bluffs. Five miles above the first falls the whole river was blocked by one straight shelf of rock, over which the water ran in an even sheet, a majestic sight.
This part of the Missouri, however, offered great difficulties to their travel. The men had now journeyed constantly for several months, and were in a region of steep falls and rapids. It was clear that they could not carry the boats on their shoulders for long distances. Fortunately they found a small creek at the foot of the falls, and by this they were able to reach the highlands. From there Lieutenant Clark and a few men surveyed the trail they were to follow, while others hunted and prepared stores of dried meat, and the carpenter built a carriage to transport the boats. They found a large cottonwood tree, about twenty-two inches in diameter, which provided them with the carriage wheels. They decided to leave one of their boats behind, and use its mast for two axle-trees.
Meantime Clark studied the river and found that a series of rapids made a perilous descent, and that a portage of thirteen miles would be necessary. The country was difficult for traveling, being covered with patches of prickly pears, the needles of which cut through the moccasins of the men who dragged the boat's carriage. To add to the difficulty, when they were about five miles from their goal the axle-trees broke, and then the tongues of green cottonwood gave way. They had to stop and search for a substitute, and finally found willow trees, which provided them with enough wood to patch up the boat-carriage. Half a mile from their new camping place the carriage broke again, and this time they found it easier to carry boat and baggage than to build a new conveyance. Captain Lewis described the state of his party at this portage. "The men," he wrote, "are loaded as heavily as their strength will permit; the crossing is really painful; some are limping with the soreness of their feet, others are scarcely able to stand for more than a few minutes from the heat and fatigue; they are all obliged to halt and rest frequently, and at almost every stopping place they fall, and many of them are asleep in an instant."
As they had to go back to the other side of the rapids for the stores they had left, they were obliged to repair the carriage and cross the portage again and again. After ten days' work all their stores were above the falls.
While they were busy making this portage they had several narrow escapes from attacks by grizzly bears. The bears were so bold that they would walk into the camp at night, attracted by buffalo meat, and the sleeping men were in danger from their claws. A tremendous storm added to their discomfort, and the hailstones were driven so furiously by the high wind that they wounded some of the men. Before the storm Lieutenant Clark, with his colored servant York, the half-breed Chaboneau, and his Indian wife and young child, had taken the road above the falls on their way to camp when they noticed a very dark cloud coming up rapidly in the west. Clark hunted about for shelter, and at length found a ravine protected by shelving rocks under which they could take refuge. Here they were safe from the rain, and they laid down their guns, compass, and the other articles they had with them. Rain and hail beat upon their shelter, and the rain began to fall in such solid sheets that it washed down rocks and mud from higher up the ravine. Then a landslide started, but just before the heaviest part of it struck them Lieutenant Clark seized his gun in one hand, and pushed the Indian woman, her child in her arms, up the bank. Her husband also caught at her and pulled her along, but he was so much frightened at the noise and danger that but for Clark's steadiness he, with his wife and child, would probably have been lost. As it was, Clark could hardly climb as fast as the water rose. Had they waited a minute longer they would have been swept into the Missouri just above the Great Falls. They reached the top in safety, and there found York, who had left them just before the storm to hunt some buffalo. They pushed on to camp where the rest of the party had already taken shelter, and had abandoned all work for that day.
While the men were building a new boat of skins, Captain Lewis spent much time studying the animals, trees, and plants of the region, making records of them to take home. Ever since their arrival at the falls they had heard a strange noise coming from the mountains a little to the north of west. "It is heard at different periods of the day and night," Lewis wrote, "sometimes when the air is perfectly still and without a cloud, and consists of one stroke only, or of five or six discharges in quick succession. It is loud, and resembles precisely the sound of a six-pound piece of ordnance at the distance of three miles. The Minnetarees frequently mentioned this noise like thunder, which they said the mountains made; but we paid no attention to it, believing it to have been some superstition, or perhaps a falsehood. The watermen also of the party say that the Pawnees and Ricaras give the same account of a noise heard in the Black Mountains to the westward of them. The solution of the mystery given by the philosophy of the watermen is, that it is occasioned by the bursting of the rich mines of silver confined within the bosom of the mountain."
Early in July the new boat was finished. It was very strong, and yet could be carried easily by five men. But when it was first launched they found that the tar-like material with which they had covered the skins that made the body of the boat would not withstand water, and so the craft leaked. After trying to repair the boat for several days they finally decided to abandon it. Putting all their luggage into the canoes they resumed their journey up the river.