Don Edwards Wildlife Refuge
The rock is a blue green in color and smooth to the touch. The above pictured giant serpentine rock has orange colored lichen growing on it. Found in Don Edwards Wildlife Refuge.

What happens when you start with mantle rock, that bendable hot semi-fluid-like rock that is miles below the surface and that the Earth’s crust floats on top of, and get it to come up a bit after mixing with ocean water and the heat induced chemical reactions that follow? You get a beautiful rock called serpentine that is usually miles deep but now makes up significant portions of the US west coast having been scraped off the ocean plates that sank below the US west coast in the last 200 million years.

A few interesting facts about this rock. It is awesome that it is the Earth’s mantle come up to the surface where we can touch it! It is the state rock of California. It can be mined for talc or asbestos. Did I mention it comes from miles below the surface? It is pretty. It is found where rocks from deep in, and below, the ocean have come to the surface through strong geologic events. The chemicals of the rock make it toxic to most plants and trees. Many California native plants have adapted to survive amongst the rock. You can see, for example, the Toyon bush (also known as California holly or Christmas berry) growing on the serpentine in the top photo.

Don Edwards Wildlife Refuge
A close up look of serpentine that is broken up a bit by erosion. It is soft and smooth to the touch as you might expect from a magnesium and talc rich rock..
Don Edwards Wildlife Refuge

Knowing that most trees and plants can not grow on serpentine rock, a previous owner of this land, now a part of the Don Edwards Wildlife Refuge, planted agave plants to add some garden interest where he hoped to build a house. While the agave was not growing naturally in this particular area, it is one of the native plants that had adapted to grow among serpentine rocks in California. Today, in this national refuge, the planted agave continues to grow.

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