lightblueline

I Found this map of the southern California region showing where the sea level was a few million years ago. Of course there has also been movement of land both lifting and lateral movement since then, so the map is very much an approximation.

NOTE however, that almost all of what is now coastal California... up to and including the Grapevine summit, was underwater. The top of Camino Cielo was beachfront.

The map was done in the 1930s.

It is from:
Reed, R.D., and Hollister, J.S., 1936, Structural evolution of southern California: American Association of Petroleum Geologists Bulletin, v. 20, no. 12, p. 1529-1704.

Here is the original website where I found the map:

Discovering the Beauty of Charmlee Park's Geological Formations