Dating methodologies in archaeology
Archaeologists use many different techniques to determine the age of a particular artifact, site, or part of a site.
Two broad categories of dating or chronometric techniques that archaeologists use are called relative and absolute dating.
It was now possible to assign a calendar date to archaeological sites in the American southwest for over 1000 years.
Determining calendar rates using dendrochronology is a matter of matching known patterns of light and dark rings to those recorded by Douglass and his successors.
Without those, the archaeologists were in the dark as to the age of various societies. The use of tree ring data to determine chronological dates, dendrochronology, was first developed in the American southwest by astronomer Andrew Ellicott Douglass.
In 1901, Douglass began investigating tree ring growth as an indicator of solar cycles.
Cross-dating of sites, comparing geologic strata at one site with another location and extrapolating the relative ages in that manner, is still an important dating strategy used today, primarily when sites are far too old for absolute dates to have much meaning.Dendrochronology has been extended in the American southwest to 322 BC, by adding increasingly older archaeological samples to the record.There are dendrochronological records for Europe and the Aegean, and the International Tree Ring Database has contributions from 21 different countries.Douglass believed that solar flares affected climate, and hence the amount of growth a tree might gain in a given year.His research culminated in proving that tree ring width varies with annual rainfall.