John Muir 
My First Summer in the Sierra [EPUB ebook] 

One of the patron saints of 20th century environmental activity, John Muirs appeal is that he not only explored the American West but also fought for its preservation. My First Summer in the Sierra is Muir’s account of working as a shepherd in the Yosemite valley, which later became Yosemite National Park as a direct result of Muir’s activism.