Santa Clara Valley

The Santa Clara Valley is a geologic trough in Northern California that runs about 90 miles south-southeast from San Francisco Bay to Hollister, roughly 93 miles long and 15 miles wide. It is a graben, a tectonic depression, lying between the San Andreas Fault to the west and the Hayward and Calaveras faults to the east, bounded by the Santa Cruz Mountains on the west and the Diablo Range on the east, and its floor is an alluvial plain built up within that structural depression rather than an erosional feature. The valley spans San Mateo, Santa Clara, Alameda and San Benito counties and has a Mediterranean semi-arid climate; once known as the Valley of Heart's Delight for its orchards, it became the technology center Silicon Valley beginning in the 1960s.