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Earth Science Conservation Review
| Runkerry Strand, Bushfoot | Antrim |
| Site number: | 1134 | ||
| ESCC: | IA | ||
| Locality Type: | Coastal section | Status: | ASSI |
| Grid Reference: | C935427 Centroid | ||
| Google maps: | 55.22292,-6.53074 | ||
| County: | Antrim | Council area: | Causeway Coast & Glens Borough Council |
| Period: | Quaternary | ||
| Stages: | Holocene | ||
| Site Description | |
|---|---|
| Highlights: | |
The highest energy beach on the Coast of Antrim and Northern Ireland, Runkerry Strand is of particular geomorphological interest. Many of the morphodynamic features in the bay are of 'text book calibre' (Carter & Bartlett, 1988), particularly since the beach describes almost the entire range of beach states from dissipative to reflective. A wide range of rhythmic morphological features are present at Runkerry, these comprise beach cusps, rip current channels, longshore rip feeder channels, giant cusps and migratory transverse and crescentic nearshore bars. The embayment's secondary fluid motions are dominated by leaky or trapped mode gravity edge waves confined in the narrow breaker zone (when an intermediate to reflective type beach is present) leading to the formation of the mentioned rhythmic topographies and subharmonic or synchronous beach cusps. | |
| Introduction: | |
Runkerry Bay, or Bushfoot Strand (Irish Grid Ref. C935427), is bounded in the west by the headland at the eastern end of Portballintrae and to the east by the western cliffs of the Giant's Causeway. At the western end the River Bush separates the beach from the cliffs. The embayment is largely fault-controlled. The large dune field which has accumulated along this fracture (the most significant is E-W trending Port-Braddan) encloses the last section of the River Bush. This dune system was formed by a relative sea-level fall and the protective role of the glacial till, operating as a strong frame for the veneer of sand, is now thought to be largely inactive (Carter & Bartlett, 1988). The dunes extend for at least one kilometre inland and two phases have been identified: an older phase, inland of the line of the tramway characterised by redder sand (5-6000 BP) and more recent deposits with a paler colouration, probably 4000 BP. The latter represents a dune-building peak with only relatively infrequent construction thereafter, and is located close to the path that now occupies the abandoned tramway and the active beach face. The whole dune system is well vegetated but is less so compared to other sites on the North Coast. The most likely reason for this is the high recreation pressure and, on the older phase further inland, destruction by grazing. Trampled footpaths along with rabbit warrens, occur throughout the dunes. Most damage, however, has arisen from recreation and farming practices, with sand removal, particularly at the northern section of the strand, traditionally leading to sediment starvation on the very active beach face. Runkerry beach presents a particularly interesting morphodynamic system especially in terms of its contemporary beach processes. Runkerry beach exhibits a nearly dissipative morphological state to an intermediate/reflective state. This change may be linked to marked seasonal variation in wave climate. The well-developed rip current circulation leads to the generation of perfect rhythmic topographies on the beach face. | |
| Description: | |
Runkerry beach is a 1.2km long, northwest-orientated beach on the coast of County Antrim, bounded by headlands composed of Tertiary basalt. The River Bush enters the sea at the western end of the bay. The area is microtidal with a tidal range of about 2m. Behind the beach is a system of mature dunes with numerous active and inactive deflation hollows. The dunes are underlain by glacial deposits which are exposed intermittently along the shore. During the Pleistocene the area was extensively glaciated by both south- and north-south moving ice sheets. Evidence of at least two episodes in the late Midlandian may be inferred from boulder clay outcrops around the bay (Stephens et al., 1975). After the dissolution of the ice sheets sea level fell below present datum around 12,000 B.P. and returned after the early Holocene (7,000 B.P.) (Carter, 1989). The primary gravel storm beach sedimentation is probably associated with the transgressive period while the dunes may have developed later as a response to slowly falling sea-levels, caused by continuing isostatic uplift into the mid-Holocene 6000-4,000 years B.P. At present both gravel and dunes are being eroded and reworked by the sea. There is obviously a lack of fresh sediment input to the beach zone, with processes therefore operating in conditions of scarcity. The beach undergoes marked seasonal changes (Shaw, 1981, 1985) between dissipative conditions during which most sediment is stored offshore as bars. These bars dissipate wave energy and protect the beach from high energy winter storms. In summer a more reflective profile develops in response to lower wave energy. Under such conditions most sediment is stored subaerially and the beach reaches its maximum extent. The transformation between the two states is marked by a succession of intermediate states as predicted by conceptual models (Short & Wright, 1980; Wright & Short, 1984). | |
| Importance: | |
In terms of contemporary geomorphology, Runkerry Strand is a classic example of dynamic morphological adjustment to variations in incoming energy. This equilibrium is nevertheless characterised by a sediment deficit. Most of the sediment in this coastal compartment is stored in the mature coastal dune system. This means that equilibrium of the cell is only achieved if dune and beach sediments flux is not disrupted or interrupted in anyway. Runkerry also represents one of the few, strongly river- influenced systems along the north coast, important in supplying terrestrial sediments to the system. It is of natural and international importance as a site in which beach stage changes can readily be demonstrated. It is on the microtidal limited section of the coast and as such is dominated by wave action over tidal currents. | |
| Interpretation: | |
Nearshore processes at Runkerry are dominated by wave action. Its northwest exposure is associated with incoming waves dominated by high energy swell resulting from sea waves generated in the North Atlantic and moving over fetches of up to 6000 km (Shaw, 1981). This produces a swell spectra of low-frequency, low-amplitude, long waves with an peaked energy spectrum. The sea-bed topography in the near shore area generates a wave regime action at the shoreline, that is produced through refraction of wave crests into a shore-normal orientation. According to the models used by the Australian school (Short, 1981), Runkerry is an excellent example of an undisturbed and dynamic beach, that never achieves the extreme end member state (dissipative or reflective) of environment. During early winter, as a result of increased modal wave height (1.5-2m Hs and 6-8 sec. T, in deep water), the beach develops a series of off-shore bars/trough morphologies. Increases in incoming energy leads to the establishment of rhythmic topographies due to sediment erosion and the formation of powerful rip currents at inter-bar locations. Rip currents fix the positions of water mass discharges and outline individual sub cells for sediment transport within the bay. Rip currents are responsible for onshore/offshore transport and the appearance of mega cusps on the beach face after high energy events. Massive seasonal loss of sediment volume is common at Runkerry beach. More than 2 meters thickness of sand was lost at the centre of the beach during the winters of 1993-1994. This volume was however, renewed in summer of 1995. This seasonal rhythmic behaviour, appears to exist in a fragile equilibrium with a tendency towards a slight sediment deficit (Shaw, 1985). The high variability in the volume of sand on the beach face illustrates its ability to respond to variations in incident energy levels. The main sediment sources (or sinks) are the dune system, and river sediment input and on-offshore movements. An unaltered sediment supply is therefore essential to maintain the equilibrium of the system. Any sediment extraction of the site will have an extremely detrimental effect on this delicate balance (Carter et al., 1992). | |
| Conclusions: | |
Runkerry beach is a classic example of a microtidal beach which describes almost the full range of beach states (dissipative to reflective) in response to variations in incident wave energy described by conceptual models (Wright & Short, 1984). Given its dynamicity it is an excellent site at which to demonstrate such processes and it is worthy of designation. | |
| Notes: | |
A complete instrumented analysis of the dynamics of the surf zone, integrated with high quality meteorological data (daily measurements of wind speed and direction, pressure, wave climate, tide gauge etc.), coupled with morphological changes on the beach face and surf zone, would present the opportunity for the development of a numerical model of beach state changes. This would contribute to the state of knowledge of such systems in general. | |
| Keywords | |
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| Relations: | Beach deposit, Coastal processes |
| Geomorph: | sand dune |
| Access | |
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| Approach: | <1km east of Portballintrae. |
| Management: | |
The dunes at Runkerry are generally immobile and well vegetated, extending up to 1km inland. Dunes situated south and east of the River Bush have however been landscaped into a golf course. Vegetation cover is relatively dense in the inland dunes but has not yet reached full maturity in relation to other dune systems in the area. Cattle grazing and recreational pressures appear to be the main reason for this. The former activity is more prevalent landward of the old tramway while recreational pressures increase with closer proximity to the sea. The presence of rabbits also exerts a significant pressure on the system creating a network of warrens throughout the dunes, enhancing erosion in places. The old tramway embankment now acts as a walkway across the back of the older dunes and appears to reduce trampling effects from pedestrians. Sediment extraction occurs on the foreshore of the northern section of the beach. The footbridge at the southern end of the beach, spanning the outlet of the River Bush, appears to have directed pedestrian traffic directly into the frontal dunes from the nearby Portballintrae. A combination of high tide and river level events, has led to a 10 metre dune retreat since the 1940's at this localised section, however, erosion along the entire Runkerry beach section does not constitute a major problem at present natural protection afforded by the boulder frame of the beach which underlies the foredunes. Although bathing is considered dangerous, Runkerry Strand is an important site for recreational activities during summer when emergent beach face is fully developed in terms of sand volume. Just to the southwest of Runkerry, lies the small town of Portballintrae developed in the nineteenth century by virtue of its proximity to the Giant's Causeway. Portballintrae offered a relatively save bathing beach. However, over the last few decades the beach has disappeared. Future management of the site should include a continuation of current restrictions on destructive recreational activities such as off road trial motorcycles. An increased number of pedestrian pathways through the dunes, beginning at the footbridge emergence area, and also information signposts for the public would help reduce erosion. It is important that sand removal be controlled, since the beach volume, although seasonally variable, is fixed. | |
| Threats: | Erosion; destructive recreational activities. |
| Uses | |
| Uses: | Cattle grazing; golf and other recreational activities. |
| References (11) | |||
|---|---|---|---|
| Carter, R.W.G., 1989. Coastal Environments: an Introduction to the Physical, Ecological and Cultural Systems of Coastlines., pp.1-617 Academic Press. | |||
| Carter, R.W.G. & Bartlett, D., 1988. Coast erosion and management in the Antrim Coast and Glens and the Causeway Coast Areas of Outstanding Natural Beauty. In Final Report of the Coast Erosion Survey. Department of Environment (Northern Ireland). | |||
| Carter, R.W.G., Eastwood, D.A. & Bradshaw, P., 1992. Small scale sediment removal from beaches in Northern Ireland: environmental impact, community perception and conservation management. Aquatic Conservation, vol. 2, pp.95-113. | |||
| Malvarez, G., McCloskey, J. & Cooper, J.A.G., 1995. Formulation of a sensitivity index based on wave/sediment interaction. In Forbairt Report, pp.74. | |||
| McCabe, A.M., Carter, R.W.G. & Haynes, J., 1994. A shallow marine emergent sequence from the northwestern sector of the last British ice sheet, Portballintrae, Northern Ireland. Marine Geology, vol. 117, pp.19-34. | |||
| Shaw, J., 1981. The morphodynamics of Bushfoot Strand (MSc thesis). (Thesis), pp.1-115 University of Ulster. | |||
| Shaw, J., 1985. Beach morphodynamics of an Atlantic Coast Embayment: Runkerry Strand, County Antrim. Irish Geography, vol. 18, pp.51-58. | |||
| Short, A.D. & Wright, L.D., 1980. Beach response to variations in breaker height. In Proceedings of the 17th International Conference on Coastal Engineering, ASCE., pp.1016-1035. | |||
| Stephens, N., Creighton, J.R. & Hannon, M.A., 1975. The Late Pleistocene period in north-eastern Ireland - An Assessment. Irish Geography, vol. 8, pp.1-23. | |||
| Wilson, H.E. & Manning, P.I., 1978. Geology of the Causeway coast. Memoir for one-inch geological sheet 7. Memoirs of the Geological Survey Northern Ireland, HMSO, Belfast. | |||
| Wright, L.D. & Short, A.D., 1984. Morphodynamic variability of surf zones and beaches: a synthesis. Marine Geology, vol. 56, pp.93-118. | |||
| Map(s): | See the 1:50,000 O.S. Sheet 4 (Coleraine). | ||
| Record type: | ESCR report | ||
| Entered by: | E M Porter | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Runkerry Strand, Bushfoot, County Antrim, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=1134. Accessed on 2026-11-08. |
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