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Outlying Sites in Fermanagh & Tyrone; FardrumFermanagh
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Summary Full report
Site Type: Karst
Site Status:
District: Fermanagh District Council
Grid Reference: H177507, H185494
Rock Age: Quaternary, Carboniferous (Chadian, Holocene)
Rock Name: Ballyshannon Limestone Formation
Rock Type: Limestone
Other interest: No data, No Data, turlough

Summary of site:

These three small lakes, one little larger than a pond, are the only true turloughs on Carboniferous rocks in Northern Ireland. Turloughs are temporary lakes that fill and drain in response to local groundwater level. When groundwater levels are low in periods of dry weather the basins are empty but in wet weather when the ground is saturated and the groundwater level is high, the lake level is determined by the local groundwater level. As with most true turloughs there are no feeder streams and no surface drainage from them. Fardrum Lough, the largest, is 250 m long and a little over 50 m wide when full.

All three are on the outcrop of the Ballyshannon Limestone which has eroded chemically to create cavities which act as conduits for supply and drainage. Only Roosky Turlough has an obvious drainage point which is the lowest point on the lake bed. Streams sinking into the limestone west of the loughs are believed to feed the local groundwater but the link is not proved. As the only true turloughs on the Carboniferous outcrop these features are important and in need of protection and conservation.

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