Dendrochronology

Dendrochronology is a scientific method used for calculating the precise age of wooden artefacts using tree-rings.

Trees grow mainly during the summer, thereby creating a characteristic pattern of circular tree-rings - each leaving its ‘mark’ in the wood. On the cut surface of a tree, you may count the amount of circles, and thereby the numbers of years represented by that piece of wood. Each year a new growth ring is created and the width varies from area to area depending especially upon the effect of climatic circumstances. Trees which have been growing within the same geographical area will normally have the same variations in the width of the growth rings over time.

If the tree is for example 120 years old, and it is compared to a building which is e.g. 80 years old, 80 of the two patterns of circles will be identical. By comparing overlapping material, a complete master profile can be established, and one may reach very far back into history.

Here you can see a sample of one of the carrying beams from the bridge across the outer moat of Trelleborg, containing 52 annular rings. The outermost ring is the youngest, and it is complete. The tree must therefore have been cut down after August of that year, and before May of the following year. Permanet

Illustration årringe datering