This magnificent Oak is on private property off Old Page Mill Road - the land it stands on is protected from ever being developed by a voluntary Conservation Easement set up by a previous owner of the property.
This image has since been used on the cover of a book describing the process and benefits of creating such easements.
The big widely-branched deciduous tree you see in the center here is the the "Valley Oak" (Quercus lobata).Wikipedia tells us that it is the largest of North American oaks, and is endemic to California,
growing in the hot interior valleys and foothills. Mature specimens may attain an age of up to 600 years.
The tree on the right is evergreen and typically smaller and denser. It is the "Coast Live Oak" (Quercus agrifolia), It is native to California, growing west of the Sierra Nevada
all the way from Northern California down to the northern part of Baja California in Mexico. It is classified as a member of the "red oak" family.