[No collecting is permitted at the petrified forest, but it's still worth visiting for anyone with an interest in rocks and geology].
The Calistoga Petrified Forest in Sonoma County, California, may not have the bright colors and beautiful agates of its more famous counterpart in Arizona - but if you love rocks and fossils, you shouldn't miss it.
[There is an entrance fee, but it's well worth it].
Enormous redwood trees lie where they fell, knocked over and buried under ash in an enormous volcanic eruption some 3.5 million years ago.
As they lay buried, water carrying silica soaked its way into the fibers of the wood, and slowly replaced the organic material with stone - preserving an extraordinary amount of detail, in the process. You can still see all the details of the bark to this day.
What makes this petrified forest particularly special, compared to the others, is the size of the trees involved.
The largest petrified log on the property is eight feet in diameter, and some 65 feet long - making the largest complete fossil tree discovered - anywhere.
It has been estimated that when these ancient redwoods were felled, they were already around 2,000 years old.
In the 1870s, a Calistoga resident discovered the trees and opened the site as a tourist attraction, and began to excavate the buried portions of the logs.
In the 1880s, Robert Louis Stevenson visited the place, and its rather eccentric owner, and wrote about his experiences in the book The Silverado Squatters.
“The first? I was that man,” said [Charlie Evans]. “I was cleaning up the pasture for my beasts, when I found this”— kicking a great redwood seven feet in diameter, that lay there on its side, hollow heart, clinging lumps of bark, all changed into gray stone, with veins of quartz between what had been the layers of the wood"[...]
And now he had a theory of his own, which I did not quite grasp, except that the trees had not “grewed” there. But he mentioned, with evident pride, that he differed from all the scientific people who had visited the spot; and he flung about such words as “tufa” and “scilica” with careless freedom.
- Robert Louis Stevenson. The Silverado Squatters
Stevenson now has a log in the forest named after him, so if you're a fan of his work, perhaps you have a second reason to go and see it.
If you'd like to read more, I recommend these books:
The Silverado Squatters by Robert Luis Stevenson
Ancient Forests: A Closer Look At Fossil Wood by Daniels and Dayvault
Petrified Wood: The World Of Fossil Wood, Cones, Ferns, and Cycads by Daniels and Britt