The annual rings vary in size, depending on the weather conditions in each region, but they are similar for all trees of the same area.
If the sequence of rings is know for a certain area it is possible to fit in all new woods found and to date them very precisely.
Stratigraphy is based on the law of superposition--like a layer cake, the lowest layers must have been formed first.
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.
In the archaeology of part-literate societies, dating may be said to operate on two levels: the absolute exactness found in political history or 'history event-by-event', and the less precise or relative chronology, as found in social and economic history, where life can be seen to change with less precision over time.
The contrast might also be drawn between two 'dimensions', the historical, and the archaeological, corresponding roughly to the short-term and long-term history envisaged by Fernand Braudel.
For Egypt and the Eastern Mediterranean, this method from European prehistory is currently under development in a project based at Vienna.