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Fallahogy Bog (Wolf Island)Londonderry
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Summary Full report
Site Type: Altitude: 43m, Inland exposure
Site Status: ASSI
District:
Grid Reference: C925075
Rocks
Rock Age: Quaternary (Holocene)
Interest
Other interest: tephra, Interglacial deposit, raised bog, grassland, temperate forest, tundra

Summary of site:

# 104. Bogs are among the best indicators of climatic and vegetational change for the period since the retreat of the last glaciers from Ireland and raised bogs are particularly informative. Raised bogs are formed when lakes are invaded by plants until the water surface eventually closes over and becomes colonised by mosses. Because they are built slowly and relentlessly by the accumulation of Sphagnum moss, they absorb the blown pollen from plants in the surrounding area and, in succeeding layers, preserve a complete sequence of plant pollens through time. Fallahogy is a bog of this kind and because it has been intensively studied it has a special and vital place in the history and continuing research into post-glacial events in Northern Ireland. It was the site of pioneering studies by Dr A.G. Smith in his quest for the earliest indications of agriculture here. His work laid the foundation for our understanding of landscape and climate in the late Irish Mesolithic and Neolithic periods, and of the impact of agricultural man.

Subsequent to this pioneering work of the 1950s, the site was revisited and samples taken for radiocarbon dating, so that absolute dates could be given to the pollen sequence. Further studies were conducted on the remains of pine trees in the bog where radiocarbon dates became the basis of tree ring (dendrochronology) studies. The carbon dates from the trees on the eastern side of the bog ranged between 7,000 to a little short of 8,000 years and dates from pine cones gathered from a layer just above the final obliteration of open water by the Sphagnum suggest that the event happened around 7,600 years ago. Large and violent volcanic events can throw massive volumes of dust-sized rock particles as high as 20-50km. At these heights they enter the atmospheric circulation in the stratosphere (or even the ionosphere) and can be carried completely round the globe. These particles of fine tephra eventually settle back to Earth under gravity, often in sufficient amounts to form event horizons in sediments. The contrast between peat and tephra suggested that bogs may be a promising environment for tephra studies and, because the Fallahogy peats were so well dated, the bog became the site of ground breaking studies. The results so far have been promising; it has even proved possible to link stunted pine stumps to an eruption of Hekla in Iceland in 2,310 BC. Recently, research on climate change has also been conducted at Fallahogy and events such as the Little Ice Age (between 1650 and 1800 AD) have been recognized, indicating the sensitivity of the bog environment. Fallahogy is one of only a handful of supremely important bogs in the British Isles, a status recognised by its designation as an Area of Special Scientific Interest. Up to the early 1990s the bog was relatively untouched but the machine cutting of peat, combined with the dry summer of 1995, damaged the bog’s hydrology (which had already been affected by a drain cut on its east side). The discharge of pig slurry into this drain, enriching groundwater that in its natural state would be nutrient-free, is another unwelcome complication. To begin to restore the hydrology it is essential now to monitor the site to prevent further peat cutting and to block the drain on the east side - otherwise irreversible damage will be done.


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