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Earth Science Conservation Review
| Dromore Big Quarry - Carboniferous | Fermanagh |
| Site number: | 235 | File Number: | H17 |
| ESCC: | ED | ||
| Locality Type: | Quarry (disused) | Status: | ASSI |
| Grid Reference: | H17457075 Centroid | ||
| Google maps: | 54.58472,-7.73086 | ||
| County: | Fermanagh | Council area: | Fermanagh & Omagh District Council |
| Period: | Carboniferous | ||
| Stages: | Arundian, Visean | ||
| Lithostrat: | Dromore Sandstone Member, Mullaghmore Sandstone, Tyrone Group | ||
| Site Description | |
|---|---|
| Highlights: | |
The quarry in Dromore Big Townland exposes sandstones that are typical of the Dromore Sandstone Member of the Mullaghmore Sandstone Formation. | |
| Description: | |
At the northern edge of its outcrop in the Kesh area the Dromore Sandstone Member rests directly on soft grey shales of the Bundoran Shale Formation. Being composed of more resistant sandstones the member forms a prominent topographic ridge with a steep north scarp face and a gently inclined southern dip surface inclined southwards at about 10 deg. and extending for 500m to the Drumskinny Road. The stratotype quarry is excavated into the steep north face of this ridge and exposes about 10m of sandstones. North of the ridge the land slopes gently northwards and is underlain by shales of the Bundoran Formation. The lowest strata of the Mullaghmore Sandstone Formation, that overlie the Dromore Member, are exposed only rarely in ditches draining the southern slopes of Dromore Big Townland. These consist of dark grey, friable, ostracod-rich shales with thin beds of black, ostracod-rich limestone and very occasionally of laminated algal (cyano- bacterial) limestone and constitute a unique package of strata, up to 7m thick, within the formation and one that is instantly recognisable throughout the Carboniferous outcrop. A total of 9.7m of bedded sandstones occur in this quarry. Bed thickness and grain size increase upwards and the top sandstone bed consists of 0.85m of very pale grey to almost white, coarse- grained, parallel laminated subarkose. Sedimentary structures are somewhat limited and include parallel laminations and, less commonly, large scale planar cross-laminations. No ripple marks were found. Indeterminate bioturbation structures occur on some bedding surfaces along with well defined Arenicolites in one example. Fragments of carbonised wood 0.03cm wide and up to 0.2m long occur on one bedding surface. | |
| Interpretation: | |
In late Arundian times the accumulation of marine shales of the Bundoran Formation gradually changed as the influx of silt and fine sand grade sediment increased. In the upper part of the latter formation these sediments maintained the overall grey colour of the underlying shales but the fossil content almost totally disappeared. The culmination of this influx of coarser sediment is reflected in the thick, clean sandstones of the Dromore Member which were deposited universally across the basin and were accompanied by a marine regression. The sandstones were probably deposited in a shallow water, high energy sandflat environment. Only in the southern part of their outcrop were there breaks in the rate of influx of the sand and thin beds, up to 0.5m, of sandy limestone were deposited. The shallow water, agitated nature of the environment of deposition is supported by the occurrence of ooliths and oolitic sandstones in the south. Sandstones in the stratotype were deposited in a marginal marine location that received increasing amounts of detritus in a location proximal to the sediment source. The top of the Dromore Member is abruptly overlain by sediments of the supratidal and intertidal facies as the supply of sand- grade material was either abruptly terminated or the locus of sedimentation moved equally rapidly. Whatever the reason sediment accumulation resumed only very slowly thereafter and, after the initial phase of sabkha facies, fully marine conditions only returned to the Kesh-Omagh area after the deposition of the Mullaghmore Sandstone. | |
| Notes: | |
For information on other sites in Subarea-3 see; Key Site 1176 - Subarea-3; Kesh-Omagh. | |
| Keywords | |
|---|---|
| Rocks: | Sand, Sandstone, Shale |
| Fossil Groups: | Arthropod, Plant, Trace fossil |
| Structures: | cross-bedding |
| Access | |
|---|---|
| Approach: | 7km north of Kesh. |
| Map(s): | See 1:50,000 O.S. Sheet 17 (Lower Lough Erne). | ||
| Record type: | ESCR report | ||
| Entered by: | Doughty, P.J. | ||
| Last updated: | 8 Jan 2005 | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Dromore Big Quarry - Carboniferous, County Fermanagh, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=235. Accessed on 2026-11-06. |
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