This book recounts the life and achievements of Clarence King, widely recognized as one of America's most gifted intellectuals of the nineteenth century, and a legendary figure in the American West. King's genius, singular accomplishments, and near-death adventures unfold in a narrative centered on his personal relationship with his lifelong friend and colleague, James Gardner. The two, upon completing their studies at Yale, traveled by wagon train across the continent and worked with the California Geological Survey. King went on to establish the Geological Exploration of the 40th Parallel, a government mapping program that stretched across the western mountain chains from California to Wyoming. This was the precursor to the U.S. Geological Survey (USGS). Founded in 1879, with Clarence King as its architect and first director, the USGS became the most important and influential science agency in the nation.

The adventurous aspects of conducting geological fieldwork in the West, much of them documented by letters written by King and Gardner, punctuate a book copiously illustrated with historic maps and photographs showing localities and people important to the story.