Dendrochronology (from the Greek dendron: tree, chronos: time and logos: science) allows the dating of wood. This fairly recent method was developed in the 20th century by A.E. Douglass, founder of the Laboratory of Tree-Ring Research at the University of Arizona. A certain Leonardo da Vinci had already linked variations in tree rings to climatic conditions…
This « reading » of the wood provides accurate dating for tree families whose seasonal growth varies according to climate. Trees of the same plant genus, e.g. oak, chestnut, elm, living or having lived during the same period of time and subjected to similar environmental conditions, develop similar ring series
Initially, this technique was used to monitor ecological changes: climatic cycles, drought or excess water events, etc. Combined with an archaeological approach, it also makes it possible to date frameworks, beams and panelling, which helps to understand the work campaigns in a building and to date a building.
As construction timber was most often used freshly felled, the absence of drying allows the date of felling to be matched with the date of installation in the houses. Within the framework of an analysis of a timber section or a frame, sampling is an essential step in order to provide significant results: it must be carried out in batches, in representative samples of old timber, with 12 to 15 core samples of five millimetres in diameter. A laboratory study is then carried out and includes a comparison with a reference database including thousands of analyses in order to issue a dating.