San Andreas Fault

By Haley Boylan 1L

The San Andreas Fault is a continental transform fault that runs a length of roughly 810 miles through California in the United States.The fault’s motion is horizontal motion.It forms a tectonic boundary between the Pacific Plate and the North American Plate.It was first identified in Northern California by UC Berkeley geology professor Andrew Lawson in 1895 and named by him after a small lake which lies in a valley formed by the fault just south of San Francisco,the Laguna de San Andreas.After the 1906 San Francisco Earthquake, Lawson also discovered that the San Andreas Fault stretched  southward into Southern California.Large-scale movement along the fault was first proposed in a 1953 paper by geologists Mason Hill and Thomas Dibblee.