How Do Trees Record Time?
ES2905  Tree Rings Record Annual Growth

As a tree grows, it produces new layers of wood around the trunk, just under the bark. If a tree is cut down, the layers are visible in a cross section. The layers appear as a set of concentric circles known as tree rings.

In general, one layer of wood grows each year. Each layer consists of two colors of wood: light-colored "earlywood" that grows in the spring and summer plus darker, denser "latewood" from the fall and winter.

  !   Examine this cross section of a tree. Identify the earlywood and latewood in several rings. Count or estimate the total number of tree rings.

USGS

1. Approximately how old is this tree? Where are the oldest rings?


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