Dendrochronology (also known as tree ring dating) is a dating method used in archaeology, but also in the geosciences and art history. It involves matching the annual rings of trees to a specific, known growth period on the basis of their different widths. The term dendrochronology dates back to the US astronomer Andrew Ellicott Douglass (1867-1962), who originally wanted to use this method to determine cycles of solar activity. Today, dendrochronology is by far the most accurate, but also one of the most widespread methods of age determination in archaeological contexts. In ideal circumstances, dating to the year can be achieved.

Constructing Chronologies from individual tree ring samples.
Source: The College of Wooster Tree Ring Lab

Dendrochronological Samples cut from posts with a handsaw at Lake Orchid. Explo-Project, University of Bern. © Marco Hostettler

In order to apply this method, of course the preservation of wood is indispensable. This means that this dating method is particularly suitable for sites that have organic preservation, e.g. Swiss or other lakeside settlements. There are wood species (e.g. oak) which, due to their biological properties and prevalence, make it easier to establish reliable and overarching main curves and thus to create an extensive basis for dating. For example, the so-called Hohenheim tree-ring calendar currently goes back without gaps to the year 10480 BCE.