THE SECRET LANGUAGE OF TREES.

As the seasons change, so do the trees secretly record memories, changing the appearance of the timber, depending on the amount of moisture and sun, as well as the years that pass. Every spring and summer the trunks grow in height and expand, and the extra inches stack on the already existing rings. When a tree is cut down, it can be deduced from the years how old the tree is and how much it has grown each year. Trees usually grow faster when young, so rings close to the middle are widest.

Dendrochronologists, experts in the study of rings, use data from the trunk to learn more about how the climate has changed over time. In good years, when the trees receive enough heat and moisture during the growing season, the trees grow strongly and their rings are wide. In bad weather, the rings are especially thin.

By studying the patterns of rings in long-lived trees, dendrochronologists analysed 7000 years and were able to calculate the exact dates of events in the Earth's history, such as shorter periods of ice ages.