ESCR - Western Mournes Complex

Earth Science Conservation Review

Summary Full report
Western Mournes Complex - Overview	Down

Site number:	450
ESCC:	IS
Locality Type:	Inland exposure
Grid Reference:	J234273,J178181,J184250,J165225,J155200,J1292 End(s) of linear site, Not Entered
Google maps:	54.18031,-6.10997
County:	Down	Council area:	Newry, Mourne & Down District Council
Period:	Quaternary
Stages:	Late Midlandian

Site Description
Highlights:
Moraine ridges and benches record retreat of ice northwest from Carlingford Lough. They record an advance through the western valleys of the Mournes and across the lowlands to the ice limit at Cranfield Point. The moraines along the Kilbroney River valley are part of a train of moraines which extends north to the Spelga Pass. These moraines record ice retreat through the valleys of the Central Mournes. The southern limit of the western moraines is the coastline at Carlingford Lough. Drumlins infer fast ice flow during the final stage of the Late Midlandian, and probably record rapid downdraw of marine-based ice. Chaotically distributed hummocks and occasional kettleholes on the lower slopes of the drumlins and in inter-drumlin areas record local ice stagnation.
Description:
The southern 200m of the Glen River valley is underlain by Tertiary G4 pink feldspar granite. The northern section of the valley and the Valley of Shanky's River are underlain by G5 non-porphyritic microgranite, which has a distinctive buff-coloured drusy appearance. The remainder of the complex is underlain by Silurian greywacke, which is penetrated by numerous dykes (Wilson, 1972). Bedrock is rarely exposed in the valley bottoms, but crops out along valley sides, where exposures several hundred metres long occur. Glacigenic deposits cover valley bottoms (<15m thick) and lower slopes (<5m). Drumlins are generally <30m higher than adjacent inter-drumlin lows but the depth of drift is not known. Drumlin alignment is northwest to southeast, and records ice flow towards the southeast.
Importance:
Little of the complex can be noted as being of particular scientific importance, as the evidence contained in the complex of ice decay patterns is repeated elsewhere in more distinct fashion. The complex therefore contributes little to a reconstruction of regional deglacial events in the region, only local patterns. For site specific information on the Western Mournes Complex see the following sites: Key Site 455 - Kilbroney River Valley Moraines Key Site 456 - Ghann River Moraines Key Site 457 - Moygannon River Valley Moraines Key Site 458 - Western Lowlands Drumlins and Moraines
Interpretation:
Drumlins are evidence of fast ice flow which streamlined the deformable, water-laden sediment substrate, and may have resulted from marine downdraw by the Carlingford ice-stream (McCabe et al., 1984). Moraines in the Kilbroney River valley record retreat northward of readvance ice which occupied the Carlingford Lough basin at around 15ka B.P. (McCabe, 1996). They are similar to moraines around Carlingford Lough and moraines which record retreat of ice through the Central Mournes, and are evidence of the synchroneity of these ice retreat events. Ice stagnation features in the lowland section contrast with the more phased retreat in the valleys, and probably reflects lower overall gradients and reduced lateral constraint, which result in flow deceleration (Shaw, 1979).
Notes:
For overview and site specific information on other sand and gravel sites within the Mourne Mountains area see the following sites: Key Site 440 - Mourne Plain Complex - Overview Key Site 447 - Attical Complex, Mourne Mountains - Overview Key Site 448 - Bloody Bridge River Valley Complex, Mourne Mountains - Overview Key Site 449 - Northeast Mournes Complex - Overview Key Site 451 - Annalong Valley For general information and references on the sand and gravel landscapes of N. Ireland, and directions to sites other than those within the Mourne Mountains area, see the following site: Key Site 439 - Introduction to the Sand and Gravel Landscapes of N. Ireland See also SLNCI Key Site 757 - Western Mournes Lowlands, Drumlins and Moraines.

Keywords
Geomorph:	drumlin, recessional moraine

Access
Management:
The aggregate resource in moraines in the western Mournes is limited and discontinuous and is unlikely to be extensively exploited. Sand and gravel in drumlins is potentially more economically viable. Quarries in these massive landforms would have a greater visual impact and be discordant with a mainly agricultural landuse. However, expansion of existing settlements, e.g. Rostrevor and Burren, is likely to have greater environmental impact. Developments should be carefully sited to prevent undue intrusion into the hummock and drumlin dominated landscape.

Access

Management:

The aggregate resource in moraines in the western Mournes is limited and discontinuous and is unlikely to be extensively exploited. Sand and gravel in drumlins is potentially more economically viable. Quarries in these massive landforms would have a greater visual impact and be discordant with a mainly agricultural landuse. However, expansion of existing settlements, e.g. Rostrevor and Burren, is likely to have greater environmental impact. Developments should be carefully sited to prevent undue intrusion into the hummock and drumlin dominated landscape.

References (8)
Hanvey, P.M., 1988. The sedimentology and genesis of Late Pleistocene drumlins in Counties Mayo and Donegal, western Ireland (Thesis) PhD thesis, University of Ulster.
Hanvey, P.M., 1989. Stratified flow deposits in a late Pleistocene drumlin in northwest Ireland Sedimentary Geology, vol. 62, pp.211-221.
McCabe, A.M., Dardis, G.F. & Hanvey, P.M., 1984. Sedimentology of a Late-Pleistocene submarine moraine complex, County Down, Northern Ireland. Journal of Sedimentary Petrology, vol. 54, pp.716-730.
McCabe, A.M., 1996. Dating and rhymicity from the last deglacial cycle in the British Isles Journal of the Geological Society of London, vol. 153, pp.499-502.
Paul, M.A. & Eyles, N., 1990. Constraints on the preservation of diamict facies (melt-out tills) at the margins of stagnant glaciers Quaternary Science Reviews, vol. 9, pp.51-69.
Postma, G., 1986. Classification for sediment gravity-flow deposits based on flow conditions during sedimentation Geology, vol. 14, pp.291-294.
Shaw, J., 1979. Genesis of the Sveg tills and Rogen moraines of central Sweden: a model of basal melt-out Boreas, vol. 8, pp.409-426.
Wilson, H.E., 1972. Regional Geology of Northern Ireland. HMSO, Belfast.

Record type:	ESCR report
Entered by:	E M Porter
Last updated:	4 Aug 2004

Enlander, I., Dempster, M. & Doughty, P., 2026. Western Mournes Complex - Overview, County Down, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=450. Accessed on 2026-11-07.