Dendrochronology dating techniques
Each region has its own unique master sequence since weather patterns are not the same from one area to another.
However, the longer bristlecone pine sequence is of little value except for cross-checking the reliability of other dating techniques because logs of this species are rarely found in association with ancient humans.
Adequate moisture and a long growing season result in a wide ring. Alternating poor and favorable conditions, such as mid summer droughts, can result in several rings forming in a given year.
This approach helps to order events chronologically but it does not provide the absolute age of an object expressed in years.
Relative dating includes different techniques, but the most commonly used are soil stratigraphy analysis and typology.
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.
The central rings of this older tree may then be compared with the outer rings or a yet older tree, and so on until the dates reach back into prehistory.