Places
The Valley's Natural History
The Santa Clara Valley we know today was created some 10,000 years ago, when melting glaciers flooded the river which emptied into the Pacific Ocean at today’s Golden Gate. The flooded river became the San Francisco Bay and its southern edge formed the new northern boundary of the Santa Clara Valley. The Valley is bounded on east and west by two separate sections of the Pacific Coast Ranges – the Santa Cruz Mountains and the Diablo Range – formed by the migration of the Earth’s plates along the San Andreas and Calaveras faults.
The San Juan Bautista Hills within the Valley are also likely the result of tectonic shift along the Calaveras fault. Their geology is largely serpentine rock – a very hard rock laced with naturally occurring asbestos. The rocky hills can be green with native grasses in the spring but are not generally suitable for agricultural uses. The serpentine rock makes a unique habitat for insects.
The hills provided the ideal spot from which newcomers could view the valley and its scope, some 15 miles across at its widest point. Spaniards, Mexicans, Americans and many others would wax poetic about the flat plain, the beautiful mountains, the temperate climate, and the amazingly fertile land.
