What else do the tree rings tell us?

Scientists also use a tree's annual rings to tell what the climate was like and what happened in the area where the tree grew. Every year the tree produces an annual ring made up of one wide, light ring (during spring and early summer) and one narrow, dark ring (during the winter). Very thick rings mean it was a good growing season with plenty of rainfall. Darker areas mean that the tree was not growing much because of lack of nutrients, less water, and less sunlight. Other markings reveal information about fires, floods, deforestation, and insect damage.