Those Tremendous Mountains by David Freeman Hawke

In 1804 Lewis and Clark set off to explore the new lands of the Louisiana Purchase. They were acting as the eyes and ears of President Thomas Jefferson, who had an insatiable curiosity about what lay between the Mississippi and the Pacific. One contingency for which they were not prepared was the awesome geography of the Rocky Mountains. Including excerpts from Lewis and Clark's journals and putting their scientific achievements in context, David Hawke presents a riveting story of this dramatic journey.