Contents

21 June 1974
Vol 184, Issue 4143

About The Cover

(Above) Fault trace a mile northwest of Olema, California, 1906. Appearance of vertical displacement is largely due to combination of horizontal displacement with slope of ground. [Photograph by G. K. Gilbert, from California Earthquake of April 18, 1906, Report of the State Earthquake Investigation Commission, Carnegie Institution of Washington, Washington, D. C.] (Below) Fault trace photographed in April 1974. See page 1283. [Wayne Thatcher, National Center for Earthquake Research, U. S. Geological Survey, Menlo Park, California]