Survey of Coastal Geology of Point Loma, California

This post is from a Facebook post nine years ago, when I was in Southern California. I’m sharing here because it discusses many features in common with the coastal geology of Washington. I just posted a report that dovetails nicely with this older report.

These sedimentary rocks were deposited during the Tertiary, when the West Coast of N. America was overriding the oceanic crust beneath the Pacific Ocean. However, geology is a complicated story, and these beaches are more than 1000 miles apart, not to mention the millions of years represented by their sedimentary rocks.

One question comes immediately to my mind: Why isn’t Southern California a subduction zone?

That requires a complicated answer…