John Muir, one of the most vigorous and restless explorers of the wilderness of the Far West in the last century achieved, between gorge-leapings, some sophisticated theories of the glacial origin of valleys in the Sierra Nevada area, extensive writings on his observations, and pioneer work in the field of conservation. This book contains writings concerned with the wilderness south of Yosemite. ""The Yosemite National Park, the John Muir Trail, the John Muir Wilderness Area of the Inyo and Sierra national forests and the Sierra Club owe (Muir) their beginnings."" No peaceful sunset contemplator he, John Muir could blister a letter page with rage at man's propensity for destruction of the wilderness. Muir's prose in repose is apt to be Victorianornate (""delicious lavings"") but once in the grip of research, he wrote forcefully, acutely.