How did the Sierra Nevada and adjacent lands come to be the size and shape they are today? This book covers 400 million years of physical evolution in a language understandable to nonscientists, tracing the volcanic activity, the folding and building of mountains, the breaking of blocks along fault lines, and the work of erosion and glaciers that have created today's dramatic landscape. Cordell Durrell spent a lifetime reading this complex story of movement and change in the rocks of the Feather River country. He shares with readers the excitement of discovering by remote but careful inference what must have happened millions upon millions of years ago. The basic methods of geologic analysis that Durrell describes can be applied anywhere on the earth's surface, lending new fascination to our travels throughout the frozen arctic, dry deserts, tropical rainforests, low swamps, and high mountains like California's magnificent Sierra.