Earth Science Conservation Review
| Barnagh Bay, Copeland Island - site of local interest | Down |
| Site Type: | Coastal section, Foreshore |
| Site Status: | local interest |
| Council area: | Ards Borough Council |
| Grid Reference: | J586841 |
| Google maps: | 54.68044,-5.54096 |
| Rocks | |
|---|---|
| Rock Age: | Ordovician |
| Rock Type: | Greywacke, Lamprophyre |
| Interest | |
| Other interest: | dyke, fault |
Description:
Two generations of intrusive igneous rocks are known within Ards Borough Council area. Dolerite intrusions of Palaeogene age are present and well exposed at Scrabo Hill. Older, lamprophyre dykes associated with the Caledonian Newry Granodiorite occur in the Lower Palaeozoic rocks of the borough.
The lamprophyre intrusions occur both as true dykes cutting across the bedding planes of the sedimentary rocks and as sills intruded conformably, or nearly so, with the bedding. Where the dykes cut across bedding they are easily recognised but recognition of the sills can be difficult as they resemble the massive greywacke units in colour and blocky aspect. In northeast County Down, no lamprophyres have been recognised in inland exposures and all those recorded occur on the wave-cut platform around the coast. The dykes are best developed on Copeland Island. At Barnagh Bay one multiple intrusion can be traced for 460m, along the south shore of the bay. It is intruded into Ordovician rocks and is off-set by numerous small faults.
The lamprophyre intrusions occur both as true dykes cutting across the bedding planes of the sedimentary rocks and as sills intruded conformably, or nearly so, with the bedding. Where the dykes cut across bedding they are easily recognised but recognition of the sills can be difficult as they resemble the massive greywacke units in colour and blocky aspect. In northeast County Down, no lamprophyres have been recognised in inland exposures and all those recorded occur on the wave-cut platform around the coast. The dykes are best developed on Copeland Island. At Barnagh Bay one multiple intrusion can be traced for 460m, along the south shore of the bay. It is intruded into Ordovician rocks and is off-set by numerous small faults.
| Enlander, I., Dempster, M. & Doughty, P., 2024. Barnagh Bay, Copeland Island - site of local interest, County Down, site summary. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/summary.php?item=715. Accessed on 2024-12-26 |
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