This guy should be required reading for every college student.
The first book I read was Desert Solitaire. It is a collection of essays prepared during his period as a park ranger in the mid 1950's. As a steward of these public lands he observed the unique perspective of humans and their environment, so geography-like.
His fiction included The Monkey Wrench Gang. Something that I can admire and dislike at the same time. I mean, I guess I am glad there are these ecoterrorists out there, But don't want anyone to get hurt physically or financially for that matter.
But in the meantime, enjoy this short video (10 minutes) about one of his speeches.