Chronological Methods 7 - Dendrochronology
Dendrochronology is another traditional technique for establishing the abolute date of events. This is also called Tree-Ring Dating. Tree-Ring dating is based on the principle that the growth rings on certain species of trees reflect variations in seasonal and annual rainfall. Trees from the same species, growing in the same area or environment will be exposed to the same conditions, and hence their growth rings will match at the point where their lifecycles overlap.
Limitations of Dendrochronology
There are limitations on dendrochronology. Some of those limitations include:
- In some areas of the world, particularly in the tropics, the species available
do not have sufficiently distinct seasonal patterns that they can be used.
- Where the right species are available, the wood must be well enough preserved
that the rings are readable. In addition, there must be at least 30 intact
rings on any one sample.
- There also must be an existing master strip for that area and species.
There is an absolute limit on how far back in the past we can date things
with tree rings. Although bristle cone pine trees can live to 9,000 years,
this is a very rare phenomenon. As we try to push our matching of archaeological
specimens beyond the range for which we have good control data, our confidence
in the derived dates diminishes.
- Finally, the prehistoric people being studied had to have built fairly
substantial structures using wood timbers. In most of the world that did not
begin to happen until about 4,000 to 5,000 years ago!
Tree-Ring Web Pages
The Malcolm and
Carolyn Wiener Laboratory for Aegean and Near Eastern Dendrochronology at Cornell
The Laboratory of Tree-Ring
Research, University of Arizona