Like everything else in Earth science this guide is the result of a cooperative effort. Numerous people in UC Berkeley’s Department of Earth and Planetary Science have contributed bits and pieces of their knowledge about the Hayward Fault. Tim Teague prepared the thin section of Founders’ Rock, Paul Renne evaluated it. Doris Sloan and Peggy Hellweg, who both have led countless tours along various sections of the fault, were always at my beck and call to find answers to whatever question I had when putting this guide together. Without the help of Samantha Teplitzky from UC Berkeley’s Earth Sciences and Map Library I would not have found old maps and pictures. I thank all of them for their generosity.