| Dendrochronology, the science of tree-ring dating, was first developed by astronomer A. E. Douglass in the southwestern United States as a way of dating climatic changes. It is based on the fact that certain tree species display annual growth rings that fluctuate in thickness from year to year depending on rainfall and other factors. Sequences of rings from living and ancient trees can be matched with one another to provide long master tree-ring sequences so accurate that wood fragments from prehistoric sites can sometimes be matched with them. Archaeological tree-ring chronologies extend back to 322 B.C.E. in the American Southwest and to as early as 9000 B.C.E. in Ireland and Germany, providing an accurate chronology for early farming in Europe and parts of North America. | 1 |
