THE SAN ANDREAS FAULT
This rift extends from El Centro on the south, 650 miles northwesterly the length of California to Point Arenas, where it continues seaward. The most publicized of California's geologic faults, it is the source of dozens of quakes annually. Of the three "monster quakes" recorded in the state (1857 - Southern California, 1872 - Owens Valley, 1906 - San Francisco) two have been along this "transform fault." A surface manifestation of the tectonic forces present as the Pacific plate collides with the North American continental plate, these forces have moved the Pacific plate 300 miles northward in the past 30 million years.
The right side says, "The 12.4-foot separation between the two portions of this monument represents the fault movement that has occurred since the modern revival of the ancient order of E Clampus Vitus at the Cliff House, San Francisco, in 1931. At this rate of movement Los Angeles will slip past San Francisco in approximately 31.5 million years and Parkfield will then be a seaside community."