Earth Science Conservation Review
| Drumarg | Armagh |
| Site Type: | Cliff, Inland exposure, Low cliff |
| Site Status: | ESCR |
| Council area: | Armagh District Council |
| Grid Reference: | H871439 |
| Google maps: | 54.33684,-6.66092 |
| Rocks | |
|---|---|
| Rock Age: | Permian (Lower Permian) |
| Rock Name: | Basal Permian Breccia, Callan Group, Drumarg Conglomerate Formation |
| Rock Type: | Breccia, Conglomeratic sandstone, Sand, Sandstone |
| Interest | |
Summary of site:
Outcrops of Permian rocks in Northern Ireland are uncommon, which makes this locality exceptional, but the rocks exposed here are unique - so special that their significance elevates them to national importance.
The only locality at which the Drumarg Conglomerate Formation can be seen is on the back wall of this abandoned quarry, which has been worked tightly up to the road. The rock has an attractive appearance and consists of angular fragments (clasts) of Carboniferous limestone, averaging 2cm in their longest dimension, suspended in a bright red-brown quartz sandstone. The limestone appears to have been derived locally because the fossils, mostly corals, are identical to those in the limestones below. Most of the clasts are stained pink from contact with the sandstone. There are rare quartz clasts and occasional fragments of the same conglomerate.
It is not absolutely certain that this rock is Permian in age because there are no macro- or microfossils in the sandstone matrix and no suitable alternative dating methods are available. However, its geological setting and comparisons with almost identical rocks in the north of England make it more than likely.
About 3.5m of roughly bedded rock can be seen in the quarry and local historic and recent boreholes show that it stands unconformably (with a time break) on the Carboniferous limestones of the Armagh Group. It is succeeded by a soft, red, fine grained sandstone (the Dobbin Sandstone), although again the relationship is seen only in borehole cores. Nowhere is it exposed. These two formations make up the Enler Group here, considered to be the earliest Permian rocks in Ireland.
The Drumarg Conglomerate was deposited around 255 million years ago in the foothills of an east-west mountain range on the newly formed supercontinent of Pangea. Limestone mountain ranges spanned the equator and the area was hot dry desert. Fans of limestone debris were washed out of the upland wadis on to the desert plain below in flash flood events, and the constant winnowing by the wind and the declining water flow after flooding filled the voids with sand.
The Drumarg Conglomerate has a further claim to fame as the preferred building stone in the early development of the city of Armagh. The Royal School's outer walls, houses on the east side of the Mall and the Infirmary are all fine examples of its use. The reason for its popularity was almost certainly the ease with which the sandstone matrix could be dressed.
Since the full report for this site was prepared, the abandoned quarry site described has been released for development and now contains a small housing estate. What was the only surviving area of quarry face is in the back gardens of houses backing on to the road and has been completely obscured. Drumarg was a potential Area of Special Scientific Interest (ASSI) awaiting designation; it is also the stratotype of the Drumarg Conglomerate Formation and a site of cultural value linked directly to the architectural history of Armagh city and environs. How such a site could be given planning permission without consulting interested parties says a great deal about the current inadequacies of the planning process. It would have been easily possible to have preserved a small corner for scientific and educational use or some reasonable alternative could have been a condition of planning permission. Since the location is easily identifiable, some future arrangement should not be ruled out.
The only locality at which the Drumarg Conglomerate Formation can be seen is on the back wall of this abandoned quarry, which has been worked tightly up to the road. The rock has an attractive appearance and consists of angular fragments (clasts) of Carboniferous limestone, averaging 2cm in their longest dimension, suspended in a bright red-brown quartz sandstone. The limestone appears to have been derived locally because the fossils, mostly corals, are identical to those in the limestones below. Most of the clasts are stained pink from contact with the sandstone. There are rare quartz clasts and occasional fragments of the same conglomerate.
It is not absolutely certain that this rock is Permian in age because there are no macro- or microfossils in the sandstone matrix and no suitable alternative dating methods are available. However, its geological setting and comparisons with almost identical rocks in the north of England make it more than likely.
About 3.5m of roughly bedded rock can be seen in the quarry and local historic and recent boreholes show that it stands unconformably (with a time break) on the Carboniferous limestones of the Armagh Group. It is succeeded by a soft, red, fine grained sandstone (the Dobbin Sandstone), although again the relationship is seen only in borehole cores. Nowhere is it exposed. These two formations make up the Enler Group here, considered to be the earliest Permian rocks in Ireland.
The Drumarg Conglomerate was deposited around 255 million years ago in the foothills of an east-west mountain range on the newly formed supercontinent of Pangea. Limestone mountain ranges spanned the equator and the area was hot dry desert. Fans of limestone debris were washed out of the upland wadis on to the desert plain below in flash flood events, and the constant winnowing by the wind and the declining water flow after flooding filled the voids with sand.
The Drumarg Conglomerate has a further claim to fame as the preferred building stone in the early development of the city of Armagh. The Royal School's outer walls, houses on the east side of the Mall and the Infirmary are all fine examples of its use. The reason for its popularity was almost certainly the ease with which the sandstone matrix could be dressed.
Since the full report for this site was prepared, the abandoned quarry site described has been released for development and now contains a small housing estate. What was the only surviving area of quarry face is in the back gardens of houses backing on to the road and has been completely obscured. Drumarg was a potential Area of Special Scientific Interest (ASSI) awaiting designation; it is also the stratotype of the Drumarg Conglomerate Formation and a site of cultural value linked directly to the architectural history of Armagh city and environs. How such a site could be given planning permission without consulting interested parties says a great deal about the current inadequacies of the planning process. It would have been easily possible to have preserved a small corner for scientific and educational use or some reasonable alternative could have been a condition of planning permission. Since the location is easily identifiable, some future arrangement should not be ruled out.
| Enlander, I., Dempster, M. & Doughty, P., 2024. Drumarg, County Armagh, site summary. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/summary.php?item=1196. Accessed on 2024-12-26 |
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