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Radiocarbon dating is

The rings are more visible in temperate zones, where the seasons differ more markedly.The inner portion of a growth ring is formed early in the growing season, when growth is comparatively rapid (hence the wood is less dense) and is known as "early wood" (or "spring wood", or "late-spring wood" Many trees in temperate zones make one growth ring each year, with the newest adjacent to the bark.

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It is also used in radiocarbon dating to calibrate radiocarbon ages.Hence, for the entire period of a tree's life, a year-by-year record or ring pattern is formed that reflects the age of the tree and the climatic conditions in which the tree grew.Adequate moisture and a long growing season result in a wide ring, while a drought year may result in a very narrow one.New growth in trees occurs in a layer of cells near the bark.A tree's growth rate changes in a predictable pattern throughout the year in response to seasonal climate changes, resulting in visible growth rings. This is an informational tour in which students gain a basic understanding of geologic time, the evidence for events in Earth’s history, relative and absolute dating techniques, and the significance of the Geologic Time Scale.

Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed in order to analyze atmospheric conditions during different periods in history.

A tree-ring history whose beginning and end dates are not known is called a floating chronology.

It can be anchored by cross-matching a section against another chronology (tree-ring history) whose dates are known.

Diagram of secondary growth in a tree showing idealised vertical and horizontal sections.

A new layer of wood is added in each growing season, thickening the stem, existing branches and roots, to form a growth ring.

Critical to the science, trees from the same region tend to develop the same patterns of ring widths for a given period of historical study.