I find it somewhat curious that no has mentioned either Ernest Hemingway or Robert Ruark. "Horn of the Hunter" by Ruark is a classic on African Safari writing and his columns for Field & Stream entitled "The Old Man and the Boy", were a mainstay of my younger days, and are a perfect example of writing that both entertains and teaches.
For pure literary merit is is difficult to find a better author than Wallace Stegner. His depiction of the west brings back tremendous memories for me and is without peer IMHO. Search him out and you will have a great read.