Patterns of seasonal variation are mostly unique and recognisable, and can date wooden artefacts, furniture, structural timbers in historic buildings, bridges and ships, or finds of wood from excavations.In well-preserved samples, the date of felling can be refined to within a season of a particular year.Note however that the date of felling is not the same as the date that the timber was used.
Dendrochronology or tree-ring dating is the scientific method of dating using the annual nature of tree growth in suitable tree species.
Dendrochronology allows the exact calendar year in which each tree rings was formed to be established enabling the precise dating of trees and timbers.
Together older trees and younger trees are used to create long, chronological, growth sequences that can help us date artifacts and archaeological sites that are hundreds, even, thousands of years old.
The sequence is created by overlaping the tree rings so a long series of rings can be seen.
This chronometric technique is the most precise dating tool available to archaeologists who work in areas where trees are particularly responsive to annual variations in precipitation, such as the American Southwest. These cross-dated sequences, called chronologies, vary from one part of the world to the next. Douglass pioneered the science of tree rings in this 1929 article titled "The Secret of the Southwest Solved by Talkative Tree Rings." Includes numerous fascinating historic photographs.
Douglass in the 1920s, dendrochronology—or tree-ring dating—involves matching the pattern of tree rings in archaeological wood samples to the pattern of tree rings in a sequence of overlapping samples extending back thousands of years.With fall coming to a close, there is no better time to talk about tree rings and their use in archaeology.You probably know that trees have rings, which you can see and count when you look at a stump after a tree has been cut, but did you know that the rings of a tree let you know how old it is?Any piece of wood from the present day backwards will usually overlap its tree ring pattern with an older piece - e.g.a tree felled in autumn 1945 may contain rings in its early (inner) pattern which will match to the outer (later) pattern of a tree felled in spring 1870. Many years of painstaking research have now compiled detailed sequences for many parts of the world, in Britain covering the last 7,300 years.Tree ring dating allows archaeologists to date when a tree was cut. Douglass was an astronomer that worked at archaeological sites in the Southwestern United States. Soon, with the rise of computers and statistical methods, scientists, like archaeologists, were able to create long series of tree ring dates that could be used to help figure out how old things are.