Mount Diablo's distinctive "pillow basalt" erupted from submarine volcanoes hundreds of millions of years ago. Learn how it made its way to the top of a mountain, in the fifth episode 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.