Scientific dating methods archaeology
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.The main drawback to dendrochronology is its reliance on the existence of relatively long-lived vegetation with annual growth rings.Secondly, annual rainfall is a regional climatic event, and so tree ring dates for the southwest are of no use in other regions of the world.
Two broad categories of dating or chronometric techniques that archaeologists use are called relative and absolute dating.
Not only that, it varies regionally, such that all trees within a specific species and region will show the same relative growth during wet years and dry years.
Each tree then, contains a record of rainfall for the length of its life, expressed in density, trace element content, stable isotope composition, and intra-annual growth ring width.
Using local pine trees, Douglass built a 450 year record of the tree ring variability.
Clark Wissler, an anthropologist researching Native American groups in the Southwest, recognized the potential for such dating, and brought Douglass subfossil wood from puebloan ruins.