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.