New Post on StoneAgeMan! How Trees Tell Time: Dendrochronology

Rob Nelson, owner of Untamed Science and now StoneAgeMan, has recently published another of my articles on his revamped website. This post focuses on tree-ring dating, or dendrochronology – a powerful archaeological dating technique.

In the right circumstances, dendrochronology can date archaeological sites to exact calendar years. That gives it a huge advantage over other dating techniques, which usually provide ranges of possible years.

Dendrochronology’s precision comes at a cost, however. I explain both its strengths and weaknesses in my latest StoneAgeMan article, along with how scientists use tree rings to date archaeological sites.

Here are the first few paragraphs of my dendro article, be sure to visit StoneAgeMan for the rest!

Did you know that trees are some of the best ‘clocks’ on the planet? You may have heard that you can determine a tree’s age by counting its rings, but if you count the rings on lots of trees you can date archaeological sites going back tens of thousands of years!

A chopped tree with distinctive rings.
A chopped tree showing distinctive rings. Image by MabelAmber from Pixabay.

Previously on StoneAgeMan, we covered relative and radiocarbon dating methods. While those are the most common dating techniques, there’s another method that can date archaeological remains to an exact calendar year, and make radiocarbon results more accurate. It’s called dendrochronology, or tree-ring dating.

Basic Premises of Dendrochronology

Trees produce rings each year that they grow. Trees grow more during wet years, producing wide rings, and less during dry years, leaving narrow rings. Since no two years have the same precipitation levels, this generates unique patterns of wide-to-narrow rings. However, because trees from the same region receive similar amounts of moisture, they develop ring patterns that are close enough to be synced up.

Dendrochronology as an Absolute Dating Method

It was an astronomer named Andrew Ellicott (A. E.) Douglass who first used tree rings to date archaeological sites. He began studying tree rings in the Southwestern United States in 1901 to see if they’d reflect sun spot activity, and he soon realized their usefulness for archaeology.

Douglass, an anthropologist named Clark Wissler, and several other researchers worked with the indigenous peoples of the Southwest to collect samples from as many trees as they could. As they obtained these samples, Douglass and his colleagues were able to arrange them in chronological order using a method called crossdating.


Crossdating starts with a tree of known age, so that…

That’s all for this brief preview! Read the rest on StoneAgeMan!

9 Thoughts

  1. There used to be a huge, ginormous slice of tree (about 6′ across if not bigger) showing it’s rings of longevity in
    Balboa Park in San Diego. What fascinated me even more was how it could also tell you, as you pointed out, periods of drought and moisture.
    I don’t believe it’s there anymore because of vandals, but it had always impressed me as a child when we took field trips to the Natural Museum.

    Liked by 1 person

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