Lesson Plan - Get It!
Imagine that you and a group of friends are out exploring the woods while on vacation in Maine. While running through the forest, you stumble on an object, trip, and fall to the ground. Looking back to see what caused you to stumble, you find you are actually lying in what was clearly a foundation for a dwelling. Curious, you start to explore and find buried in the remains a few objects that you assume belong to the people who once lived there. How long ago were people living there? What kind of science might help you figure this out?
Archaeologists and other scientists typically rely on one of two methods for dating the age of artifacts and other items of historical significance.
One method, called dendrochronology, determines the age of an object based on a comparison to the pattern of tree rings taken from sample trees in the area.
Counting the tree rings from the outside to the inside is a reliable method for determining the age of the tree. The trees in the area might not all be the same age, but they will share the same pattern of light and dark, thin and wide rings at points indicating the type of weather for the region.
If you then take a log from the historical dwelling, or a wooden object within the site, and match its pattern of rings to one of your samples, you can tell how long ago the tree used for that log was cut down. This indicates how long ago the people who left the artifact lived.
Understanding how dendrochronology works is easier if you have some background about how trees grow. Here is a quick overview of how rings form within tree trunks: Growth ring, from Encyclopædia Britannica.
Continue on to the Got It? section to learn more about this science.