ESCR - Ballykelly - deglacial landscape

Earth Science Conservation Review

Summary Full report
Ballykelly - deglacial landscape	Londonderry

Site number:	469
ESCC:	IS
Locality Type:	Inland exposure	Status:	TBC
Grid Reference:	C6723,C658183,C627223 Corners of site, Not Entered
Google maps:	55.05031,-6.9517
County:	Londonderry	Council area:	Causeway Coast & Glens Borough Council
Period:	Quaternary

Site Description
Highlights:
The two main areas of stratified drift form the central part of a more extensive morainic complex which occurs as a southward facing arcuate belt. This moraine is scientifically important because it records the last major surge of Scottish ice southwestwards into the Lough Foyle lowlands. The ice limit, marked by the morainic complex, is therefore regionally important for the interpretation of deglacial sequences farther south in the Faughan and upper Dungiven depression. It was responsible for damming large extraglacial lakes against the margin of retreating ice along the north face of the Sperrin foothills. In a wider scientific context it not only illustrates the morphological and sedimentological characteristics of a major ice marginal surge but also documents the dynamic character of the last ice sheet margin. This glaciological inference is critical for future ice sheet modelling especially the concept of rapid environmental change and changes in ice sheet configuration around the margins of the last British ice sheet. Similar large-scale surges, which may also be related to major meltwater events, have now been recognised from the marginal sectors of the last ice sheet (Celtic Sea; North Sea; Irish Sea). Detailed sedimentological and dating comparisons between these events from different marginal sectors of the ice sheet will be important for future research programmes. The Ballykelly complex is therefore of national and international importance. Aesthetically the topographic diversity provided by the stratified drift at Ballykelly and Moys is unique in the lower Foyle Lowlands. Discrete zones of ridges, kettle-holes and hummocky topography provide distinctive landform changes between Lough Foyle and rising ground to the south. The forms are generally intact and most of the old quarries have now been landscaped.
Description:
Stratified sands and gravels occur in two main zones west of the lower Roe channel. They form the central part of a morainic complex dominated by low (<15m high), discontinuous till ridges. Laterally, the stratified drift grades into complex till and gravel ridges at Ardmore (270900 420900) to the east, at Sistrakeel (261600 419600) and Glack (261500 417300) to the west. The most southern ridge complex trends south-east to northwest between Moys/Largy (267300 419300) and Thorny Hill. It consists of discontinuous ridge segments up to 30m in height at Moys. These coalesce northwestwards into well-defined round-crested ridges at Drumraighland (264200 419800) and Clagan (264100 420700), ending in Ballykelly Forest (261000 421800). The stratified drift occurs up to 110m O.D. and dies out as a feather edge immediately south of the Moys to Glenhead (263900 419200) road. A partially overgrown pit at Moys consists of glaciotectonically disturbed, poorly-sorted, cobble gravels mainly composed of schist (>80%) clasts, with numerous (<5%) granite erratics probably of Scottish origin and occasional chalk pebbles (<5%). The northern complex lying south of the Ballykelly/Limavady road is up to 30m in height and consists of broad, round-crested ridges. Overall the complex trends east-west but individual ridges do not maintain a consistent orientation. Enclosed depressions and small (<20m deep) post-glacial channel incisions are common. One temporary exposure at Oakdene (264100 422700) consisted of 7m of large-scale gravelly foresets which dipped south at 15°. Topsets were not present. The foresets consisted of massive beds (10-50cm thick), of poorly-sorted, pebbly gravel. Erratics of Cretaceous chalk, flint and Tertiary basalts occur together with granitic rocks of Scottish provenance.
Importance:
Identification of well-defined surge topography on the Lough Foyle lowlands is of national importance. Evidence for preservation of large scale, surge topographies is critical for ice sheet modelling and critical evaluation of deglacial events in NW Britain. No other evidence for major onland surge events is known in Northern Ireland or the Republic of Ireland. Similar features have been recognised in east Yorkshire. At present small exposures along the Curly River show that the complex is underlain by the fine-grained deformed sediments. These record deformation of subaqueous outwash as the surge progressed to its southern limit. Both the internal geometry and external expression of the surge event are well-preserved. It is pointed out that these attributes are rarely preserved in the stratigraphic record and are of extremely high scientific interest. An important future element will involve attempts to date this event in order to reconstruct a more accurate deglacial chronology and the relationship of the surging ice to former Late glacial sea level.
Interpretation:
Ridge trends, foreset dip and erratic carriage from the western slopes of Binevenagh (basalt) show that the Ballykelly moraine is associated with variable sedimentation at the margin of an ice lobe that moved southwestwards into the Foyle lowlands. The stratified deposits clearly form the central part of the morainic complex. Till ridges to the east (Ardmore/Ardgarvan) and west (Dunbrock, Lisneal, Tirmacoy) are clearly ice-push features and may be either subglacial or ice marginal. The central stratified core was deposited from a subglacial meltwater efflux. The innermost ridges are essentially deltaic at Oakdene and the outer ridges at Moys are ice pushed. The overall depositional setting is identical to that formed by submarine surges described by Solheim (1985) and Solheim and Pfirmam (1985) from the Barents Sea. Typically these surges are marked by an outer glaciotectonised ridge, subparallel to the ice margin, and inner complex patterns of till ridges recording the expression of relief on the glacier sole. The central stratified ridges represent concentrated meltwater flow as the lobe decayed. Glacier surges may occur independently of climatic variations although they do imply sufficiently high precipitation over a period of time to build up unstable mass distribution. The Ballykelly moraine is the only example known in Ireland to record the large scale, morphological expression of surge activity. It is the close association and field relationship between the central meltwater outlet complex and the ice pushed or pressed ridges on either side which provide the critical evidence for a major surge event. At Sistrakeel the morainic complex is underlain by Early Devensian glaciomarine sequences, though the precise contact is not exposed. No suitable organic or shelly horizons have been found in the moraine and its dating remains problematical. Regional evidence suggests it post-dates the maximum extent of Irish Ice northward into the Malin Sea and drumlin formation but predates the late glacial raised beach sequence and the Portballintrae shallow marine sequence. The northern margin of the moraine is cut by late glacial beach gravels leading to a subdued beach notch around 21m O.D. To the east meltwater erosion associated with the Roe and Castle channels cut the moraine out. It is replaced to the east of Limavady by an extensive late glacial delta at Fruitfield.
Notes:
For general information and references on the sand and gravel landscapes of N. Ireland, and for directions to other regional sand and gravel sites, see the following site: Key Site 439 - Introduction to the Sand and Gravel Landscapes of N. Ireland

Keywords
Rocks:	Gravel, Sand
Relations:	Deglacial sediments, Surge event
Geomorph:	deltas

Measurements
Length:		Width:		Height:
Depth:		Area:	20km2

Access
Management:
The morainic belt forms a rolling, extensively cultivated belt along the southern margins of the highly scenic Lough Foyle estuary and western margins of the Antrim plateau. The ridges provide elevated viewpoints over the aesthetically pleasing situation of Limavady town atop the Fruitfield delta and the raised beach and coastal flats around Lough Foyle. The belt has been quarried in several locations, one of which 0.75km east of Ballykelly town has been reclaimed and converted into a dirt-track motorcycle racing course. At Moys, to the south and centre of the belt, disused workings provide the locations for a brickworks and unsightly dump, apparently used on an ad hoc basis for the disposal of household waste.

Access

Management:

The morainic belt forms a rolling, extensively cultivated belt along the southern margins of the highly scenic Lough Foyle estuary and western margins of the Antrim plateau. The ridges provide elevated viewpoints over the aesthetically pleasing situation of Limavady town atop the Fruitfield delta and the raised beach and coastal flats around Lough Foyle. The belt has been quarried in several locations, one of which 0.75km east of Ballykelly town has been reclaimed and converted into a dirt-track motorcycle racing course. At Moys, to the south and centre of the belt, disused workings provide the locations for a brickworks and unsightly dump, apparently used on an ad hoc basis for the disposal of household waste.

References (2)
Solheim, A., 1985. Submarine evidence of glacier surges Polar Research, vol. 4, pp.91-95.
Solheim, A. & Pfirmam, S.L., 1985. Sea floor morphology outside a grounded, surging glacier: Brasvellbreen, Svalbard Marine Geology, vol. 65, pp.127-143.

Record type:	ESCR report
Entered by:	E M Porter
Last updated:	23 Dec 2003

Enlander, I., Dempster, M. & Doughty, P., 2026. Ballykelly - deglacial landscape, County Londonderry, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=469. Accessed on 2026-11-05.