As the Corps of Discovery approached this river valley, the convergence of several rivers forced Captains Meriwether Lewis and William Clark to choose a route. Lewis and a few men went ahead to investigate the rivers and, after exploring, he left a note recommending that Clark take the men and canoes up the Jefferson River. He tied the note to a sapling at the fork with the Wisdom River, also called the Big Hole, but a beaver apparently chewed down and carried away the sapling, so Clark never saw the message. When Clark reached the fork, he chose the Wisdom River instead. That river proved narrow and choked with encroaching willows along its tight curves. One canoe capsized and two were swamped before one of Lewis's men found them and the group reunited. Today, the Jefferson River and Valley are known as the Beaverhead, the Wisdom River was renamed the Big Hole, and the Philanthropy was renamed the Ruby. Beavers were plentiful along the Beaverhead River when the Corps of Discovery passed through in 1805, and they chew on saplings for the sweet cambium layer just under the bark.