The San Andreas Fault extends from El Centro northwesterly for 650 miles along 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 earthquakes annually. Of the three monster quakes recorded in the state, in 1857 in Southern California, 1872 in Owens Valley, and 1906 in San Francisco, two occurred along this transform fault. As a surface manifestation of tectonic forces where the Pacific plate collides with the North American continental plate, it reflects forces that have moved the Pacific plate 300 miles northward in the past 30 million years. The 12.4-foot separation between two portions of the monument represents fault movement since the modern revival of the ancient order of E Clampus Vitus at the Cliff House, San Francisco, in 1931, and at this rate of movement Los Angeles will slip past San Francisco in approximately 31.5 million years, with Parkfield then becoming a seaside community.