Rock art is one of humankind's most ancient forms of artistic expression, and one of its most enigmatic. For centuries, scholars and other observers have struggled to interpret the meaning of the mysterious figures incised or painted on natural rocks and to understand their role in the lives of their long-vanished creators. The Great Basin of the American West is especially rich in rock art, but until recently North American archaeologists have largely ignored these most visible monuments left by early Native Americans and have given little attention to the terrain surrounding them. In Great...