An introduction to tree ring dating
They are the lungs of the world, breathing in carbon dioxide and breathing out the oxygen on which animal life depends.They live in all sorts of conditions too: in temperate and tropical areas and in arid locations, from mountain landscapes to the rainforests of the equator and the temperate uplands of Scandinavia, they are everywhere.This page does not attempt to cover the details of wood formation that make tree rings possible, but rather provides an overview of common wood characteristics and anomalies that you will need to identify when you are crossdating.Variation in these rings is due to variation in environmental conditions when they were formed.Dendrochronology is the study of the growth of tree rings and we can learn much from their study.We can date organic archaeological material and create a chronological record against which artefacts can be dated (3).Thus, studying this variation leads to improved understanding of past environmental conditions and is the basis for many research applications of dendrochronology.
In each growth season, trees create a new ring that reflects the weather conditions of that growth season.
The dawn of the age of true trees came with the evolution of wood in the late Devonian period.
Before this, their ancestors would have a recognisable tree form, believed to be that of a giant type of fern that began the process of developing a woody stem.
There is much we can learn about the past climate, how freak season-long weather conditions, or periods of climate change have affected tree growth and how it may affect our climate in future.
American Astronomre A E Douglass, who had a strong interest in studying the climate, developed the method around 1900 (4).