The Bog Wood Story


Buried trees and forests are common and widespread in Irish bogs.In extensive areas of the west of Ireland entire forests of pine lie preserved underneath the blanket bog.

In raised bogs, pine forest is part of the natural vegetation succession from lake to bog. The three important types of wood found preserved in bogs today are scot's pine, oak and yew. They can be from 4,000 to 7,000 years old. Pine, often referred to as deál or fir, is found deep in the bog, and occurred in times when the drying of surface peat allowed a migration of pines on to the bogs. These scot's pine woodlands were open in character and had an understorey of birch. In the ground layer ericaceous shrubs or heather species were important including ling heather and crowberry. They were maintained on the bog for up to 500 years. Eventually the bog surface became unsuited to tree growth and regeneration of the woodland. As the climate became increasingly wetter and bog growth became active again the trees were drowned and seeds could not germinate.

Oak and yew trees are generally found around the edges of the bogs in the midlands and were drowned as the bog expanded out of its basin onto the surrounding mineral soil. The lack of oxygen in waterlogged peat prevents the natural process of decay and ensures the tree trunks and stumps are preserved for years in the accumulating peat.

Scientifically, bog wood has proved invaluable as a dating tool and for studying climate change. This is made possible because of annual variation in the diameter size of tree rings. Tree rings are wide in a good growth year and narrow in a poor growth year. Studying variation in the pattern of tree rings is known as dendrochronology. By studying and matching the patterns in tree rings from a wide range of bog wood samples, a year by year chronology can be built up. Queen's University in Belfast has a tree ring record compiled from 4,000 year old bog oak and other ancient oak timbers that spans 7,000 years. A pine chronology for Ireland is also under development. The tree ring chronology allows accurate dating of anything made from oak or pine in Ireland. The annual growth rings in bog wood timbers also give a record of past climatic conditions. The basis of these studies lie in the fact that in a favourable growth year the tree lays down a wide growth ring. In unfavourable years, a narrow ring and so on. The patterns in the rings analysed using statistical packages and related to calendar years give a detailed record of climate change over time.

The Celtic Roots Studio sent samples of bog oak and bog yew to Queen's University Belfast to get the samples of wood carbon dated. The results that came back are as follows:

Radiocarbon dating at Queen’s University, Belfast confirms; " In providing dates along with sculptured wood, you can safely say, in the case of bog yew, that the date of the growth of the wood is between 2,000 and 2,200BC and for the bog oak, the date of growth of the wood is between 3,300 and 3,600BC."
Dr. F.G. McCormack, Radiocarbon Research Unit.