ESCR - Bloody Bridge River Valley Complex, Mourne Mountains

Earth Science Conservation Review

Summary Full report
Bloody Bridge River Valley Complex, Mourne Mountains - Overview	Down

Site number:	448
ESCC:	IS
Locality Type:	Inland exposure
Grid Reference:	J377269 Centroid
Google maps:	54.17308,-5.89129
County:	Down	Council area:	Newry, Mourne & Down District Council
Period:	Quaternary
Stages:	Late Midlandian

Site Description
Highlights:
The sediments and landforms in the Bloody Bridge valley and associated landforms on the coastal lowlands immediately east of the valley document the sequence of events which occurred during the Late Midlandian period in the eastern Mournes area. The pattern of morainic and outwash deposits relate to the retreat of an ice lobe northwards along the coast and westward into the mountains, recording the separation of a valley glacier from the coastal ice lobe during the main Late Midlandian retreat phase. The deposits in the Bloody Bridge river gorge record the phased retreat of a valley glacier into the highlands of the Mourne massif during this deglacial phase. Cross-cutting patterns of moraines in the Bloody Bridge valley indicate a later, localised ice advance from a corrie in the Chimney Rock mountain associated with an oscillation of the ice front of indeterminate amplitude. A fan outside the limits of the cross-valley moraines records glaciofluvial deposition during the waning of this advance. The sequence of events recorded in the Bloody Bridge river valley is important in reconstructing Late Midlandian palaeoenvironments in this region and can be compared with similar readvance landforms in neighbouring valleys.
Description:
The Bloody Bridge Valley drains eastwards from the Mourne Mountains towards a wide coastal tract in the southeast corner of Co. Down. The upper 2.7km of the valley is underlain by G2 granite, which has been injected into the local Silurian country rock to form the eastern Mournes (Wilson, 1972). The quartzose granite, containing abundant dark quartz, and local porphyritic orthoclase, is the most abundant Tertiary bedrock in the eastern Mournes. A remnant of the Silurian greywacke structural roof crosses the area of the complex 200m north of the Glen Fofanny-Bloody Bridge River confluence. The major contact between the granite and the greywacke belt which completely encircles the Mourne massif occurs 100m south of the confluence. The bedrock is completely covered by up to 10m of glacigenic deposits except where these have been incised by the rivers. The Bloody Bridge River has cut a gorge up to 20m deep and 100m wide along the its lower 2.5km. The gorge is incised into up to 10m of mainly glacigenic deposits, and exposes the underlying bedrock along its central section. The complex consists of four major morphological/sedimentological elements. The sequence of sediments in the main valley channel shows outwash deposits (e.g. at J377269) overlain by two cross-cutting sets of cross-valley moraines. A glaciofluvial fan (J387270) occurs beyond the margins of the cross-valley moraines. For site specific information on the Bloody Bridge River Valley Complex see the following sites: Key Site 452 - Bloody Bridge River Outwash Key Site 453 - Bloody Bridge River Valley Ridges Key Site 454 - Bloody Bridge River Fan
Importance:
The Bloody Bridge river valley contains important evidence of a significant Late Midlandian climatic fluctuation. The deposits show that the main retreat phase associated with climatic amelioration and the rapid decay of the Irish Sea glacier and land based Midlandian (Late Devensian) ice sheet was followed by a readvance of ice from a localised centre on the eastern flank of the Mourne Mountains. This readvance was possibly related to a relatively minor and short lived climatic deterioration in the Younger Dryas period. Although similar sequences of events are recorded elsewhere in the Mourne Mountains the pattern and sedimentology of deposits in this valley clearly demonstrate the retreat/readvance/retreat sequence.
Interpretation:
Sediment exposures are rare in many of the landforms in the valley. Thus the interpretation given is largely based on the topographical relationships between landforms and regional models of ice decay in the area. Cross-cutting of the main retreat phase moraines by deposits originating from corrie-based ice is unequivocal evidence for readvance eastwards along the Bloody Bridge River valley. The moraines in the Bloody Bridge River valley thus record the final phases of ice activity along the eastern flanks of the Mourne massif. It is probable that this example of a major readvance of corrie ice was contemporaneous with the readvance of lowland ice recorded by the moraines in Carlingford Lough, on the northern flanks of the Mournes, and in the White Water Valley. Readvancing valley ice in the Annalong Valley and the Silent Valley were also probably part of this regional pattern. A build up of ice in such diverse source areas as the Lough Neagh lowlands, and Mourne corries and ice centres suggests that a regional climatic deterioration may have been the trigger for the readvance.
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 449 - Northeast Mournes Complex - Overview Key Site 450 - Western Mournes - Overview Key Site 451 - Annalong Valley For general information and references on the sand and gravel landscapes of N. Ireland, and for directions to sand and gravel 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

Keywords
Relations:	Glacial deposit, Glacio-fluvial sediment
Geomorph:	corrie, cross-valley moraine, glaciofluvial fan, valley glacier

Access
Management:
The remoteness, small size and poor quality of the Bloody River valley aggregate deposits, coupled with the lack of easy vehicular access as well as the proximity of more economic resources on the Mourne Plain, make it unlikely that the valley will be exploited as an aggregate source. The Bloody Bridge river valley is a much-used route into the High Mournes area and would benefit from the deposit's continued preservation. Granite quarries in the valley are at present not worked. It is likely that this will continue to be the case with the decline in use of granite as a building material. However, small-scale granite quarrying is an integral part of the cultural-historical landscape of the Mournes, and this could be considered positively in an area where natural bedrock outcrops are common. Of greater concern is the potential for degradation as the result of the increasing use of the valley for leisure activities, with attendant slope and path erosion and littering problems.

Access

Management:

The remoteness, small size and poor quality of the Bloody River valley aggregate deposits, coupled with the lack of easy vehicular access as well as the proximity of more economic resources on the Mourne Plain, make it unlikely that the valley will be exploited as an aggregate source. The Bloody Bridge river valley is a much-used route into the High Mournes area and would benefit from the deposit's continued preservation. Granite quarries in the valley are at present not worked. It is likely that this will continue to be the case with the decline in use of granite as a building material. However, small-scale granite quarrying is an integral part of the cultural-historical landscape of the Mournes, and this could be considered positively in an area where natural bedrock outcrops are common. Of greater concern is the potential for degradation as the result of the increasing use of the valley for leisure activities, with attendant slope and path erosion and littering problems.

References (7)
Boulton, G.S., 1986. Push-moraines and glacier-contact fans in marine and terrestrial environments Sedimentology, vol. 33, pp.677-698.
Charlesworth, J.K., 1955. The Carlingford readvance between Dundalk, Co. Louth and Kingscourt and Lough Ramor, Co. Cavan Irish Naturalists Journal, vol. 11, pp.299-302.
Harvey, A.M., 1984. Debris flows and fluvial deposits in Spanish Quaternary alluvial fans: implications for fan morphology numb. 10 In CSPG Memoir 10, Sedimentology of gravels and conglomerates, pp.123-132.
Middleton, G.V. & Hampton, M.A., 1976. Subaqueous sedimentation transport and deposition by sediment gravity flows In Marine sediment transport and environmental management, pp.197-218 Wiley, New York.
Postma, G., 1986. Classification for sediment gravity-flow deposits based on flow conditions during sedimentation Geology, vol. 14, pp.291-294.
Rust, B.R. & Koster, E.H., 1984. Coarse alluvial deposits In Facies Models, 2nd Edition, Reprint Series Geoscience Canada, Ontario.
Wilson, H.E., 1972. Regional Geology of Northern Ireland. HMSO, Belfast.

Record type:	ESCR report
Entered by:	E M Porter
Last updated:	8 Jan 2005

Enlander, I., Dempster, M. & Doughty, P., 2026. Bloody Bridge River Valley Complex, Mourne Mountains - Overview, County Down, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=448. Accessed on 2026-11-05.