"A book of great sweep and of sharp and shifting focus. It portrays the hugeness, harshness and magnificence of the land and the stamin and ardor of the men who took its measure."--New York Times After the Civil War, four geological and geographical surveys, later called the Great Surveys, Undertook the massive task of finding out what lay west of the hundredth meridian in the vast American wilderness. Parties led by Ferdinand Vandiveer Hayden, medical...