Surface features revealed by the Viking Orbiter were 10 times smaller than those recorded by Mariner 9, 30 times smaller than those features seen from Mariners 6 and 7, 300 times smaller than those features in Mariner 4 images, and 15,000 times smaller than our best pre-1964 earth-based views. The book about Mars had to be rewritten following each increase in resolution. Mutch et al. (The Geology of Mars, Princeton University Press, Princeton, N.J., 1976) and W. K. Hartmann and O. Raper (The New Mars, NASA Spec. Publ. 337, 1974) provided us rewrites following Mariner 9. Carr provides us a comprehensive rewrite following the historic Viking missions.