To eliminate individual variations in tree-ring growth, dendrochronologists take the smoothed average of the tree-ring widths of multiple tree samples to build up a ring history, a process termed replication.A tree-ring history whose beginning and end dates are not known is called a floating chronology.Adequate moisture and a long growing season result in a wide ring, while a drought year may result in a very narrow one.

For instance, missing rings are rare in oak and elm trees.

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.

A tree's growth rate changes in a predictable pattern throughout the year in response to seasonal climate changes, resulting in visible growth rings.

Each ring marks a complete cycle of seasons, or one year, in the tree's life.

Growth rings are the result of new growth in the vascular cambium, a layer of cells near the bark that is classified as a lateral meristem; this growth in diameter is known as secondary growth.

Visible rings result from the change in growth speed through the seasons of the year; thus, critical for the title method, one ring generally marks the passage of one year in the life of the tree.

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.

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.

Use that office closet for more than storing old yearbooks.