By Tim Clancy, for Let's Talk Plants! January 2022.
About 600 miles from San Diego in Arizona is a National Park named the Petrified Forest. The park is home to many fine examples of trees that are now in a state of petrification. It is by some accounts the most famous collection of petrified wood in the world. Petrified wood is wood that is fossilized. Fossilized wood comes in three flavors, petrified, mummified and submerged in water.
Submerged wood does not rot due to a lack of oxygen among other things. This is why we see wooden pilings sunk into rivers and lakes for a multitude of purposes. Submerged wood can come from logs that sank during the logging process or sometimes trees fall into lakes and rivers. Trees that were formerly growing in valleys (eons ago) became submerged when those valleys got filled with water. Sometimes humans create dams that also end up submerging wood. Wood that naturally makes its way to an underwater resting place is sometimes logged and milled for use in construction such as floorboards. This is an interesting process in and of itself.
Mummified wood is wood that has undergone some changes but still retains organic qualities. This is wood pre-petrified. As a matter of fact, this wood may never become petrified if the conditions which lead to petrification are absent. Think of mummified wood as wood that has been desiccated. A walk in the woods should reveal several examples of what qualifies as mummified wood.
Petrified wood is wood that has been transformed by the addition of minerals such as iron and copper. These minerals “take the place” of wood and maintains the wood shape and characteristic look. Most of the petrified wood we know of today is over 100 million years old. The process to become petrified is not for the impatient as it takes between 5,000 to 10,000 years.
Monkey puzzle trees, ginkgos and palms are some of the tree types that make up petrified wood. There are other species and not all species around the world have been identified yet. Black, green, yellow, pink, brown-red and orange are all colors found in petrified wood. These colors are the clues as to what minerals were involved in the petrification process. Copper, manganese and iron being but a few. There is seemingly something to match any décor.
The Petrified Forest National park website has some great information about the park and petrified wood. There is an FAQ for the curious. One fascinating fact is that petrified wood weighs between 160 to 200 pounds per cubic foot!
As of this writing you need not visit Arizona to see a piece of a petrified log. In front of the recently sold Encinitas landmark, Captain Keno's, is a petrified log. It has been there as long as I can remember and I have been in Encinitas since 1987. It sits on an old 55-gallon oil drum looking like someone may have placed it there as a temporary holding place. I suppose if you favor an unassuming style then its current display is perfect. I might be more inclined to celebrate the existence of a “tree” that may be 100 million years old with at least a plaque or something.
Who knows how long it will remain, as the new owners have plans to develop the area (they also purchased adjacent land).
So, if you want to see a piece of petrified wood without going to Arizona head up to Captain Keno’s and have a look!