Andrew Lawson was first to map the San Andreas Fault. But the cantankerous UC Berkeley geologist had more than a few blind spots.

It's episode 22 of the TRAIL THROUGH TIME, a series of geology videos featuring naturalist Ken Lavin. Sponsored by the Mount Diablo Interpretive Association in partnership with Save Mount Diablo. Videography by Macha Rose. Animations by Tanya Atwater, UC Santa Barbara. Music by Phil Heywood. Produced by Joan Hamilton.