Introduction to tree ring dating
Tree-ring dating is formally known as “dendrochronology” (literally, the study of tree time).
The unique features of tree rings are a direct result of their formation through xylogenesis.
The Laboratory of Tree-Ring Research (LTRR) at the University of Arizona has a good introduction to tree-ring dating.
The Tree Ring Lab (TRL) at the Lamont-Doherty Earth Observatory is also an excellent source of information about tree ring studies and is also a source of software of use in tree-ring studies.
But, as children we may not have realized that patterns of rings can be compared among trees to determine the exact year in which rings were formed (Fritts, H. Precise dating of events involving the “maiming or killing” of a tree is possible because tree growth is affected by variations in climates, and the “yearly sequence of favorable and unfavorable (wet and dry or warm and cold years) is faithfully recorded by the sequence of wide and narrow rings in large numbers of trees (Fritts, 1976).
Tree rings are distinct, variable, and therefore datable.