Tree ring dating examples

In coniferous species (pine, fir, spruce) the “ring” or layer is made up of light colored “earlywood” or “springwood” terminated with a dark layer of small, thick-walled cells called “latewood” or “summerwood”.

Various species of trees like oak, chestnut, pine, elm, and fir, for example, produce annual growth rings whose width depends on moisture and climatic conditions.

There is also a difference in the nature of the wood from the exterior bark, the outermost growing layers where the sap flows (the sapwood) down to the heartwood and core of the tree.

The rings are the cambium layer, a ring of cells that lie between the wood and bark and from which new bark and wood cells originate; each year a new cambium is created leaving the previous one in place.

How large the cambium's cells grow in each year--measured as the width of each ring--is dependent on seasonal changes such as temperature and moisture availability.

This layer, or ring as seen in cross section, can be wide, recording a wet season, or narrow, recording a dry growing season.

Because the rings are basically recording a good growing season or a bad growing season, they are indirectly recording more than just moisture.

Dendrochronology, or Tree-ring dating, has emerged in the last decade as one of the most important dating tools for medieval carpentry and timberwork in general.

Briefly stated, dendrochronology creates a statistically-based calendar from the meticulous measurement of the variation in width and character of annual tree rings.

Dendrochronology is the study of climate change as recorded by tree growth rings.

Each year, trees add a layer of growth between the older wood and the bark.