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Aghatirourke Townland caves, east CuilcaghFermanagh
PHOTO TO BE ADDED Cave west of Legacurragh Gap, Aghatirourke Townland, east Cuilcagh, Co. Fermanagh.
Summary Full report
Site Type: Cave
Site Status: PASSI
District: Fermanagh District Council
Grid Reference: H15613098, H15553067
Rock Age: Carboniferous (Visean)
Rock Name: Carn Limestone Member, Dartry Limestone Formation
Rock Type: Limestone, Shale
Fossil Groups: Brachiopod, Coral, Crinoid, Polyzoan
Other interest: No data, Marine sediments

Summary of site:

The Carboniferous Limestone in Co. Fermanagh is dominated by the considerable thickness of the Dartry Limestone Formation. A ‘formation’ can be subdivided into smaller rock units called ‘members’, each of which must be defined by the description of lower and upper limits. The rocks in the area where this work is done become the ‘stratotype section’, which can then be used by geologists as a standard of comparison for rocks of the same age.

The short sections in the two Aghatirourke caves constitute the stratotype for the Carn Limestone Member, which forms the very top of the Dartry Limestone Formation in this part of Fermanagh. The base of this member is seen in one cave and the top in the more northerly one. The two caves are correlated by a bed of limestone nodules common to both sections. The Carn Limestone Member consists of alternating beds of grey limestone and shales. The fossil fauna includes crinoids, brachiopods, bryozoa and solitary corals. It was originally described from the Carn/Boho area but no stratotype could be defined there since neither base nor top is exposed. This is why the Aghatirourke caves are so important. The Carn Limestone Member, with its dark limestones and shales, gives the first indication of deltas from a northerly land mass spreading muddy sediments into the pure lime sediments of the tropical sea. The Carn Limestone is missing over parts of the area; its absence is explained by a period when the sediments were irregularly exposed to the weather and eroded away in places before the following Meenymore Formation deposits were laid down.

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