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Carbon Dating aka Radiocarbon Dating

One of the dating methods most people think of when they talk about archaeology is radiocarbon dating. This is one of the absolute dating methods that archaeologists use to date an artifact. Only organic materials can be dated using this method, but archaeologists can also use it for inorganic artifacts sometimes too.  If an inorganic artifact, like pottery or stone tools, comes from the same layer of soil as an organic artifact, like plant remains or bone tools, archaeologists can use the age of the organic artifact to assign an approximate age to the inorganic artifacts as well.

Even though radiocarbon dating is a pretty well known technique not all archaeologists that have organic samples are able to do it, or perhaps more importantly, the funds to do it. It can cost over $600 to run these kinds of special scientific tests so sometimes archaeologists need to rely on other dating techniques instead.

The science behind it all… Read more

Dendrochronology, a.k.a. Tree Ring Dating

With fall coming to a close, there is no better time to talk about tree rings and their use in archaeology.

You probably know that trees have rings (which you can see and count when you look at a stump after a tree has been cut), but did you know that the rings of a tree let you know how old it is? Tree ring dating allows archaeologists to date when a tree was cut. The method was developed in the early 20th century by A.E. Douglass.  Douglass was an astronomer who worked at archaeological sites in the Southwestern United States.  By the 1960’s, tree ring dating spread to Europe.  Soon, with the rise of computers and statistical methods, scientists, like archaeologists, were able to create long series of tree ring dates that could be used to help figure out how old things are Read more

Index Types

Note: Archaeologists don’t dig up dinosaurs… or fossils… but we borrowed this method from our Paleontology friends.

Index fossils are fossils that are used to identify a particular period of time.  Archaeologists don’t look for fossils, but they can use other types of artifacts that don’t decay to do something very similar.

One type of artifacts archaeologists find are stone tools.  Stone doesn’t decay, so these artifacts can sometimes be the only thing archaeologists find at very old sites.  What archaeologists often find are small chips of stone or the debris (debitage) from making stone tools; other times they find a whole tool.  When archaeologists find a whole tool, they compare it to the index type from the different time periods.  If the artifacts match archaeologists can date the site the artifact was found at to that time period.

Chances are you’ve been using a simple version of this kind of method since you were a kid!  Do you remember this song from Sesame Street? Read more


Next time you go to the mall take a look at the cars around you. Can you tell which ones are newer and which ones are older? You probably have a good idea of which ones are older even if you don’t know anything about cars. Take a look at the image below. Chances are, you can tell the 1981 Honda Accord apart from the 2014 model just by looking at them!

And what about clothes? If you saw someone wearing a patchwork sweater you can be sure they bought it in the 1970s. That’s because the things that people make and use change in appearance over time. One fashion style might be new and unpopular at first, but soon everyone is wearing it. Then, one day, the baggy patchwork sweater you used to love is no longer trendy and gets replaced by shoulder pads! Read more