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Petrified wood find

I found a piece of, what appears to be, petrified wood on a Santa Barbara beach agaist the cliffs. Is this a piece that the museum would be interested in given I obtain proper permissions to retrieve? When I came across,  it was setting on a rock and appeared to be physically placed there. I would hate to see it removed by somebody in the future. It weighs about 15-20 pounds.

Ted, Santa Barbara - March 13, 2021

Curator Response

Hi Ted,

Thank you for thinking of us! This isn't petrified wood, though. From the photos, it looks like this interesting-looking specimen is a piece of weathered sandstone. The rings around the edge suggest it has matured in a way known as rind-weathering. The appearance of rings or a bark-like layer—which probably contributed to your first seeing this rock as a piece of wood—is likely the result of a chemical reaction and recrystallization of minerals on the surface of the rock, caused by weathering from water and air. We may also be seeing the related—and not wholly understood—phenomenon known as Liesegang banding, another chemical transformation that can produce beautiful concentric rings and lines that mimic wood.

Just for fun, we'll attach a picture here of some petrified wood that our naturalists like to share with guests in the Museum Backyard. This specimen has been polished, making it really easy to see the telltale structures highlighted by the colors of different substances present when silica passed into the wood and slowly replaced it, bit by bit.

Petrified wood is rare here, for basically the same reason we have very few terrestrial dinosaurs: this portion of California was mainly underwater. In some places though, we can find mostly small pieces of wood or charcoal that have been swept in the ocean by prehistoric rivers.

Stay curious,

Santa Barbara City College Earth and Planetary Sciences Instructors Sabina Thomas, Ph.D., and Jenna Rolle, M.S.