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.
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.
Seriation is thought to be the first application of statistics in archaeology. The most famous seriation study was probably Deetz and Dethlefsen's study Death's Head, Cherub, Urn and Willow, on changing styles on gravestones in New England cemeteries.For example, JJA Worsaae used this law to prove the Three Age System.For more information on stratigraphy and how it is used in archaeology, see the Stratigraphy glossary entry.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.