The Rocky Mountains are one of the Earth's most spectacular geological features, containing vast stretches that remain wild and untamed. Hikers on mountain trails often see the wilderness just as Lewis and Clark saw it almost 200 years ago. The diversity of life found along the Rockies' 2,000-mile range is so varied that the mountains are divided into three regions: the Northern, Central, and Southern Rocky Mountains. Scott A. Elias discusses the unique features of each region in his comprehensive natural history of "the backbone of the continent." Elias examines the physical environment of each of the three regions, looking at geology, important land forms, climatology, soils, water resources, and paleontology. Equally detailed chapters examine botany, invertebrate zoology, native fishes of the plains and mountains, reptiles, amphibians, birds, and mammals. Elias also includes a history of the native peoples and a synthesis of activities since the Spanish colonial period in the Southern Rockies. Conservation topics are woven throughout the book and the final pages examine the problems of overuse and overcrowding in national and state parks. Elias offers recommendations to alleviate these problems and stresses that the Rockies are a national treasure and should be treated as such.