Called 'the Thoreau of the South West,' ~ wrote many provocative, controversial, and always entertaining books about his love of nature, and his disdain for the industrialization of the great outdoors.
He coined the phrase Industrial Tourism.
He has a great collection of essays, called Desert Solitaire ISBN:0345326490, and his most famous book, The Monkey Wrench Gang ISBN:0060956445 (fiction).
While Abbey himself promoted the ideas of monkeywrenching (environmental terrorism to some), he did not have any special fondness for any group, especially not the SierraClub.