Traces the natural and cultural processes involved in shaping the environment in the intermontane northwest from the Indian period of domination to the present. Emphasizes the increasing influence of humans as modifiers of landscapes and ecosystems, especially with the coming of the market system to the region and the onset of the industrial era. Focuses on the unique aspects of ecological change in the intermontane region: the very recent extension of the market system to the area; and the very rapid expansion of human-induced environmental disturbance over very extensive areas in a very brief span of time.