Tree rings are not always good indicators of the passage of time…

Claimed to be capable of providing dates for a piece of timber up to 8 or 9,000 years back in time, this dating method can be unreliable beyond 1600 years before present.

How is that possible? Known in science as dendrochronology, this is the counting of annual tree growth which forms an extra ring over each season. The difference in colour is due to the change in the cell structure of the heart wood in the core of each tree, and the outer ‘sapwood’. This outer layer grows well in spring and summer months mainly, but not always regularly around the tree.