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Doagh Glebe Townland QuarriesFermanagh
Roadside quarries, Derrygonnelly-Garrison road, Doagh Glebe Townland, Co. Fermanagh.
Summary Full report
Site Type: Quarry (disused), Roadside section
Site Status: PASSI
District: Fermanagh District Council
Grid Reference: H04865163, H053517
Rocks
Rock Age: Carboniferous (Brigantian, Visean)
Rock Name: Carraun Shale Formation, Doagh Limestone Member
Rock Type: Limestone
Interest
Fossil Groups: Brachiopod, Gastropod, Microfossil, Microfossils, Polyzoan
Other interest: No data, Marine sediments

Summary of site:

All rock units (stages, formations, members, etc.) that bear a name are defined in an area and from rocks that typify them. Such key exposures are called ‘stratotypes’ and this site is the stratotype of the Doagh Limestone Member of the Carraun Shale Formation, the very last formation of the Visean epoch of the Carboniferous period.

This stratotype is a composite section, exposed in a series of small quarries on the south side of the Derrygonnelly to Garrison road. The total thickness of the member is estimated at about 8m but the longest section, with a thickness of 6.1m, occurs in the quarry below the forestry observation tower. Small outcrops along this line of quarries complete the full thickness. The limestone is pale grey to pale brown, medium to coarse grained and made up of pellets and spheres (ooliths) set in clear calcite cement. It contains fossils of lime-fixing algae, lamp shells (brachiopods), moss animals (bryozoa) and sea snails (gastropods), all selectively replaced by silica. One genus of microscopic foraminifera indicates that the member was formed at the beginning of the Brigantian (the last stage of the Visean), around 333 million years ago. The member has been correlated with the Tawnyunshinagh Limestone Member on Cuilcagh Mountain and in the neighbouring counties to the south. All stratotypes should be protected as the founding rock units of Northern Ireland geology.


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