Contents

06 October 1972
Vol 178, Issue 4056

About The Cover

Salton Sea and Imperial Valley of California looking of Arizona.The valley is lengthening at up to centimeters per year by crustal spreading motions on the San Andreas, San Jacinto, and Elsinore fault systems. See page 15. [Gemini Vphoto, courtesy of NASA and Department of Geography, University of California, Riverside]