Science of dating trees
Many trees in temperate zones make one growth ring each year, with the newest adjacent to the bark.For the entire period of a tree's life, a year-by-year record or ring pattern is formed that reflects the climatic conditions in which the tree grew.
Absolute dating methods are used to determine an actual date in years for the age of an object.This method is based on the assumption (which nearly always holds true) that deeper layers of rock were deposited earlier in Earth's history, and thus are older than more shallow layers.The successive layers of rock represent successive intervals of time.Compare the timeline you recorded to the one shown here. Consider another situation: What if you found a sample of wood and constructed a skeleton plot for it, but it did not match any patterns on the master chronology? If necessary, go back to Step 8 and realign the patterns to see how this master chronology was constructed.
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." The outer portion is the "late wood" (and has sometimes been termed "summer wood," often being produced in the summer, though sometimes in the autumn) and is denser.