Before Lewis and Clark completed their expedition, Americans could only speculate on what lurked in the uncharted territories beyond the Rocky Mountains. Even Thomas Jefferson, who’d amassed a small library of books on the frontier, was convinced the explorers might have run-ins with mountains of salt, a race of Welsh-speaking Indians and even herds of wooly mammoths and giant ground sloths. The expedition failed to sight any of the long-extinct creatures, but Lewis did describe 178 previously unknown species of plants and 122 new animals including coyotes, mountain beavers and grizzly bears.
