How Old Is Petrified Wood? (An Answer With Examples!)

How Old Is Petrified Wood?

Petrified wood is created when, in another time, trees that have fallen get washed downstream and eventually buried under layers of mud and ash from volcanoes and other materials. And since they were buried so well and in the perfect conditions, they became completely sealed beneath the mud and ash.

The air was unable to reach the buried wood, and without oxygen, the wood was unable to start the decay process. But slowly…very, very slowly, the material in the tree began to break down. And as it broke down, voids were created. And over the milenia, those voids were slowly filled with the surrounding minerals and other material such as silica, calcite, pyrite and opal.

How Old Is Petrified Wood?

Over millions of years, these minerals that have made their way into the tissue of the buried tree crystallize clear down into wood’s cellular structure. This crystallization process forms the hard-as-stone material you know as petrified wood. And even though it’s no longer wood, the minerals that have crystalized in its place take on the appearance of the tree it replaced…clear down to the tree rings.

So, petrified wood is over millions of years old. But that still doesn’t narrow it down. Millions of years is a pretty wide gap. Below are a few examples of how old the petrified wood is in different parts of the world. It’s pretty astounding.

According to the website for the Petrified Forest National Park in Arizona, “…the trees in the Black Forest were deposited about 211 million years ago and those in the Blue, Jasper, Crystal, and Rainbow Forests were deposited around 218 million years ago.

And The Times Of India mentions that the petrified wood located in the National Fossil Wood Park contains fossilized wood that is 20 million years old. It also mentions that the Akai Wood Fossil Park has specimens that are an astounding 180 million years old!

But if you think that’s old, there is an area in Brazil that has dated some of their petrified wood samples to be as old as 280 million years!

How Do They Determine How Old Petrified Wood Is?

But how do we really know how old petrified wood is? Well, scientists have technology that can help them help them determine the age of the petrified wood specimen.

According to, there are a few different ways that scientists are able to determine how old petrified wood is.

Relative Dating: By determining the age of the sedimentary rocks in which a fossil is buried. In order to accurately date petrified wood using this method, one must have a good knowledge of the geology of the area in which the fossils are found.

Biostratigraphy: By dating the age of other known organisms fossilised within the same layer. These known fossils are referred to as “index fossils”.

Radiometric Dating: By calculating the percentages of radioactive elements.

Not All Petrified Wood Is Ancient

So now that you’ve settled on the fact that petrified wood is millions of years, I’m about to throw a curveball at you. Did you know that under the right conditions, some wood can begin to mineralize and begin the petrification process in less than 10 years?  It’ true.

In a article, it was observed that fresh samples of wood had fallen into a hot spring, and these “new” pieces of wood were already petrified.

So an experiment was done.

According to the article, “fresh wood pieces of alder wood (Alnus pendula Matsumura) were placed in the hot spring water stream. Experimental wood fragments were silicified to nearly 40% by weight over a period of 7 years by the deposition of amorphous silica spheres in cell lumina of wood tissue.”

They go on to say that the results of this study confirm that under the perfect conditions, silicified wood can form “…in time periods as short as tens to hundreds of years.”

Final Thoughts

So, I think it’s safe to say, unless given certain specific conditions that are just right, that petrified wood is millions of years old. And every time I find a piece of petrified wood, it causes me to pause for a moment and think about what used to be. That the area I now call home has not always been like this. That the deserts of the American Southwest were once covered in forests. And palm trees once grew in the cold and rainy regions of the Pacific Northwest.  

What do we see around us now that will be unearthed 100 million years from now?

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