The geologic history of Edgewood is traced back 35,165 million years ago when the rock that underlies much of this region was formed by two converging tectonic plates, the Farallon and North American. The Farallon plate was forced under the American plate and large amounts of rock were left behind. One, serpentinite, is a very rare rock type that is found at Edgewood. This underlying rock is a very unique feature of the Park that can be observed in the serpentine grasslands and rock outcroppings.
The vegetative history of Edgewood reflects numerous geologic and climatic changes. Relics of Neotropical forest (California Bay Laurel, California Buckeye), Actotertiary forest (Coastal Redwood, Douglas-fir) and Madroteriary forest (Madrone, Manzanita, and Poison Oak) are found there.
The human history of the region shows that hunters were in the region 6,000 years ago. About 500 AD. Ohlone speaking peoples came to the bay area. Two Ohlone archeological sites have been found nearby, one at Filoli Estates and one at Phleger Estates. In 1769, the Spanish exploring party of Gaspar de Portola marched through the region and made the first Ohlone-Spanish encounter.