A brief account of the Scots-born originator of the U.S. national park system draws upon standard works by and abut Muir but emphasizes his early years in Wisconsin and at the University of Wisconsin in Madison to a greater extent than most other biographies for young readers. Full-color scenic photos and maps; black-and-white archival images of Muir, his family and colleagues; brown-and-white sketches and other images of Muir's inventions and notes; brief side-bar quotations by Muir and others; and listings of conservation-related organizations contribute to this introduction to an activist's vision, life and works. (Ages 11-14)