Summary of site:
Sluggan Bog is of a type called lowland raised bog. Such bogs began as shallow lakes with sedge and reed margins, usually in lowland areas. As the lakes slowly filled with mud, the reed beds encroached further into open water, depositing their own debris in the form of fen peat, until eventually vegetation totally covered the water surface. As the fen peat grew in thickness, all nutrients were leached out by rain. Slight increases in rainfall at this point in the cycle created perfect conditions for the growth of Sphagnum, a moss requiring virtually no nutrients and able to store rainwater with great efficiency. Once Sphagnum became established, it grew uninterrupted while ever there was sufficient rainfall (a permanent condition here). It then continued to grow on its own decay debris, usually resulting in a bog with an elevated dome-like form - hence the name.
Sluggan Bog, in its unbroken depositional sequence of 5-6m of peat, contains a continuous record from late Pleistocene times (about 13,000 years ago) to the mid-late twentieth century. Research on the pollens in the bog, from base to top, has yielded a complete history of the plant colonization of the surrounding area for the last 13,000 years, firmly pinned to an absolute time scale provided by radiocarbon dating.
Pines became established on the bog during its development and their stumps and root systems are readily preserved in the bog environment. Their growth rings reflect annual climatic conditions and the sequence of changes over the lifetime of the tree form diagnostic patterns that can be correlated with other trees. By comparing the patterns from overlapping sequences in generations of pines, a continuous record of climate over thousands of years is possible. It can again be tied to radiocarbon dates to give absolute ages or even linked through to the present day by simply counting back. Dendrochronology is the name given to the study of tree ring dating and important fundamental research has been conducted at Sluggan Bog.
Only in recent years has it been realised that the finest particles of volcanic dust (tephra), blasted high into the atmosphere during exceptionally violent volcanic events, can be carried thousands of miles - or even circumnavigate the globe - in the upper atmosphere. This means that tephra can settle tremendous distances away from its source but, apart from ice caps and deep ocean basins, there are few environments in which it can be detected. Pioneering research at Sluggan was able both to detect tephra deposits and to establish accurate dates for the volcanic events they represent.
The surviving uncut remnant of Sluggan Bog is no longer active. Turf cutting and agricultural drainage have lowered the water table, causing the surface to dry out and the Sphagnum moss to die. But this has not robbed the bog of importance and research potential. Over the last 35 years, no lowland raised bog in Northern Ireland (or perhaps anywhere) has been as intensively studied as Sluggan. Its contribution to our understanding of prehistoric environments, not only in Ireland, has been of outstanding importance and its perennial research relevance means that Sluggan Bog should be preserved even though it will progressively degrade over the coming decades.