Define seriation 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.The scholar most associated with the rules of stratigraphy (or law of superposition) is probably the geologist Charles Lyell.The basis for stratigraphy seems quite intuitive today, but its applications were no less than earth-shattering to archaeological theory.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.It was now possible to assign a calendar date to archaeological sites in the American southwest for over 1000 years.
In 1929, they found a charred log near Show Low, Arizona, that connected the two patterns.Many of the first efforts of archaeology grew out of historical documents--for example, Schliemann looked for Homer's Troy, and Layard went after the Biblical Ninevah--and within the context of a particular site, an object clearly associated with the site and stamped with a date or other identifying clue was perfectly useful. Outside of the context of a single site or society, a coin's date is useless.And, outside of certain periods in our past, there simply were no chronologically dated objects, or the necessary depth and detail of history that would assist in chronologically dating civilizations.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.
In other words, artifacts found in the upper layers of a site will have been deposited more recently than those found in the lower layers.