Unfortunately, the only true way of ascertaining where the position of wood (be it a small item, or a large item), is find bark or sapwood, in which case we can say for certain that it came from the outer portions of the tree. However, in theory, it may be possible to identify where in the lifespan of a tree that wooden sample originated. This is because most species of trees follow three growth patterns depending upon their age; Formative, middle age, and senescence. In the Formative stage, tree rings get progressively wider after germination as the tree develops more and more foliage as it grows. After around 40-100 years (depending upon species and some external factors), the tree enters "Middle age" with growth of foliage and canopy/crown having become optimum, and subsequent growth rings will be uniform in size. However, as more and more rings are put on around the circumference of the tree, the rings start to become less thick, as the same volume of material area of material is deposited around a larger circumference. When the tree enters old age, the crown of the tree may die back, or have sustained damage, with consequently less support for foliage, and the tree rings become even narrower, until the point where the tree can no longer sustain itself and it dies.

I mentioned above that this is all in theory, as external factors can influence the development of growth rings. For example an old tree can appear to be in its formative period due to being overshadowed/overcrowded by other taller trees. If these other trees should die, or get blown down in a storm, there can be a sudden growth release due to the sudden increase in light. The uniform rings that would normally form in middle age could be mistaken for a transition to senescence rings because the local environment/climate changed resulting in conditions of poor growth. Annual insect attack on a younger tree could also make the wood appear to be senescent.

When it comes to looking at tree rings in archaeological artefacts, even large samples, it may be difficult ascertaining which part of the tree it came from due to a low number of tree rings. For example, it may not always be the case that a wooden sample will be cut through a tree radially, preserving an abundance of radially concentric tree rings to examine. Transverse sections of wood may be taken from tree trucks for the likes of planks and wooden boards/panels, which means that only a small cross section of rings are present, making identification of the growth period of a tree it was harvested from very difficult; do you have a narrow rings due to old age, or due to temporarily poor growing conditions. Do you have a section of wide rings formed when the tree was young, or was it a period of growth release due to the surrounding population decline? Was the wood taken from the middle aged section of a tree that died centuries after that section grew, or was the tree felled while it was still middle aged? So many questions, which are perfect if you doing a dendrochronological/palaeoecology project on preserved trees, but probably too many to be helpful in an archaeological context.

This is why the radiocarbon dating of ANY wood, must be treated cautiously and and the interpretation of the data tempered within the context of its deposition/emplacement. As I mentioned elsewhere, one should not be surprised when radiocarbon dating of wood within archaeological contexts give us dates older than thought for that context.

Jonny

The path to good scholarship is paved with imagined patterns. - David M Raup