ESCR - Carey Valley

Earth Science Conservation Review

Summary Full report
Carey Valley	Antrim

Site number:	463
ESCC:	IS
Locality Type:	Inland exposure, Pit, River bank	Status:	ASSI
Grid Reference:	D007361,D127408 End(s) of linear site, Not Entered
Google maps:	55.16225,-6.41999
County:	Antrim	Council area:	Causeway Coast & Glens Borough Council
Period:	Quaternary

Site Description
Highlights:
Scientifically, the most important part of this glaciofluvial complex occurs in the middle part of the valley 1km southeast of Ballyvoy (315600 440600), where an extensively developed, flat-topped delta surface is related to a palaeo-water plane at 100m O.D. (Mc Cabe and Eyles, 1988). Meltwater flow northwards from a subglacial efflux constructed a large delta which prograded from an ice-margin at Tormore (320500 437900). The delta structure resembles a classic Gilbert-type feature (Gilbert, 1885). 'Typical' deltaic sediments are exposed in the river scars and pit at Drumadoon where the delta surface is well preserved. Downvalley, later postglacial incision by successive meltwater erosional events created a series of stepped terrace fragments and entrenched meltwater channels. The well-preserved delta surface within a protected topographic low is scientifically important because it demonstrates that a high relative sea level of approx. 100m O.D. existed as the coastal tract around Ballycastle was deglaciated and ice withdrew southwards. High relative sea level (HRSL) suggests that the major control on deposition was deep isostatic depression at the periphery of the ice sheet. Aesthetically, the gravelly sequences choking the axis of the valley provide a high range of topographic diversity within a basin dominated by a continuous girdle of monotonous hills rising to around 300m O.D. The glacial topography shows contrasts including flat delta tops, dissected terrace stairways, steep-sided meltwater gashes and flat-bottomed meltwater channels. These topographically diverse settings are largely intact and combine to provide a distinctive landscape assemblage not shown elsewhere in Co. Antrim.
Description:
The lower part of the Carey Valley is funnel shaped and underlain by faulted Carboniferous strata (Wilson, 1972). From Drumadoon southwards the bedrock element of the valley is incised across a Dalradian complex, Cretaceous chalk and Tertiary basalt. In this valley sector the present river occupies a steep-sided and flat-topped meltwater gorge up to 35m in depth and about 4km in length. The channel begins in a blind intake at 250m O.D. about 1km south of Loughareema lake. The location of the lake, astride the meltwater system, is associated with rocky knolls whose margins have been cut into a series of rock bounded meltwater channels up to 15m in depth. Along most of the upper valley the rock margins are buried by thick sequences of stratified drift, which fade laterally over 100-150m into the diamict mantling the rock of the surrounding high ground. Three distinct sedimentological/morphological elements are recognised: A Along the valley sides south of Tormore, flat spreads to low hummocks occur along the shoulder of the meltwater gash. The latter is up to 30m in depth and occasional exposures indicate that the former fill in the upper valley is composed mainly of amalgamated beds of poorly-sorted cobble gravel. Laterally, the gravels fade out over 100-200m against rising ground. The most southerly extent of the gravels occurs as low hummocks on the western margins of Loughareema where small sections show interbedded diamicts and gravels. This detritus is composed mainly (90%) of Dalradian clasts and up to 5% granite erratics. B Where the main valley opens northwards between Carrowndoon (318300 439700) and Drumadoon, a magnificent flat delta surface rises gently northwards from a low morainic ridge at Tormore. The front of the delta surface is steep and parallels northward dipping gravelly foresets which suggests it is an original prograded delta front. The delta surface defined at the foreset/topset contact is at 100m O.D. It is recognised that the delta surface is largely a depositional rather than an erosional feature and was controlled by a water plane around 100m O.D. Sections in a river scar near Drumadoon (316700 440500) and along the main road at Drumnakeel (316400 440000) allow the valley fill to be reconstructed in a composite log. Two main lithofacies associations (LFA) are recognised: 1) A diamict/gravel lithofacies association occurs at the base of the Drumadoon outcrop. The diamict (<10m) consists of stacked beds of poorly-sorted admixtures of sand, silt and clay containing dispersed pebbles and cobbles (Mc Cabe and Eyles, 1988). Upper and lower diamict beds are separated by chaotically bedded and poorly-sorted boulder/cobble gravel beds up to 5m in thickness. 2) The lower LFA is overlain by a coarsening upwards sequence of laminated silty clays, sands and gravels which are expressed morphologically as the Drumadoon delta. The lower part of this LFA consists of flat-lying, thinly-bedded rhythmites overlain by massive sands. Upwards, large scale gravelly foresets dip (18-22°) consistently to the west-northwest (280-300°). Inclined bedding surfaces are planar to tangential immediately about the angular contact with the underlying sands and clays. The uppermost part of this LFA consists of crudely-bedded, flat lying beds of poorly sorted pebble and cobble gravel. C Between Drumnakeel and The Friary thick sequences of laminated silts and sands are overlain by gravels. The sequences have been extensively eroded into flights of glaciofluvial terraces which occur over an altitudinal range of between 20m and 90m O.D. Individual terrace fragments are defined by sharp slopes eroded by glacial meltwaters and are highly variable in plan view, ranging from elongate to triangular. Exposures are small and restricted to valley side cuts.
Importance:
The scientific importance of the complex is classified as unique for one major reason - the preserved delta top records high relative sea levels in response to isostatic downwarping around the periphery of the last British ice sheet. Major landforms of this type have a low preservation potential, largely because of rapid rates of ice retreat due to marine downdraw coupled with rapid environmental change leading to post-depositional erosion by meltwater. Drumadoon is a magnificent example of a classic Gilbert-type delta in pristine condition. The stratigraphic architecture of the feature itself is not however scientifically unique and is frequently found in many other depositional settings within Ulster.
Interpretation:
Field relationships between the glaciofluvial landscape elements, inferred ice conditions/limits and the local topography indicate that the following sequence of events occurred during deglaciation in this basin: A The ice sheet's margin withdrew southward from the continental shelf and halted at Tormore where a relatively small frontal moraine developed. This interpretation is also supported by the south to north hydrostatic gradient controlling drainage, indicating the presence of thicker ice to the south. At this stage the upper valley acted as a subglacial drainage feeder channel to the ice margin and, judging by the vast amounts of sediment in the lower valley (~0.11km3), pumped large volumes of heterogeneous debris northward. At Loughareema the main subglacial channel's discharge was augmented by flow from a series of englacial channels creating a plunge pool on the site of the present lake. LFA 1, which consists of interbedded diamict and chaotically structured gravel, found along the valley bottom, records deposition on a slope fed by large volumes of heterogeneous debris. These sediment gravity flows record rapid facies changes associated with ice margin fluctuations and sedimentation pulses downvalley from thick and unstable sedimentary aprons. The latter accumulated rapidly in response to a substantial hydraulic head beneath the ice margin ( e.g. Gustavson and Boothroyd, 1987). B The overlying clay, sand and gravel sequence (LFA 2) comprises the essential component of a classic Gilbert-type delta. Palaeocurrent data indicates delta progradation downvalley on top of the lower fill (LFA 1). The depositional environment was probably akin to a glacier-fed fjord-head delta (e.g. Syvitski et al., 1987). The delta is undoubtedly related to a water plane at about 100m O.D. To the north there is no evidence to suggest that this level is associated with a readvance of Scottish ice onto the north coast impounding a glaciolacustrine waterbody within the valley (cf. Hill and Prior, 1968; Stephens et al., 1975). It is suggested that the water plane at 100m was controlled by high relative sea level. This interpretation is in keeping with the known regional patterns of downwarping around the margins of the last British ice sheet (e.g. Mc Cabe et al., 1994). C The lower delta fragments north of Drumadoon commonly show evidence of extensive glaciofluvial erosion and abandoned meltwater channels. Different terrace levels cannot be related directly to any specific sea level trends, simply a relative fall in sea level since late glacial times. Nevertheless the amount of erosion indicates that substantial amounts of meltwater was available after deglaciation to effect deep scouring and significant changes in the terrace forms. The Drumadoon delta itself has been bisected by a major meltwater gash now occupied by the misfit Carey River.
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
Relations:	Deltaic sediments, Glacio-fluvial sediment, Glaciolacustrine deposit
Geomorph:	prograded delta
Paleoenv:	deglacial

Access
Management:
The existence of an observable glaciomarine delta surface in such pristine condition makes the Carey valley infill of considerable geomorphic importance. The sand and gravel facies dominate the topography of what would otherwise be a glacially overdeepened river valley with gently sloping sides. They greatly enhance relief and shelter on the valley-floor for grazing animals. The present flood plain of the Carey River is a picturesque gorge secluded from main thoroughfares and home to small brushwood and riverbank habitats. The exposure at Drumadoon is of national importance. Additional exposures are scarce and, most gravel pits are by now abandoned and vegetated. Some that are present form scars on the upper rim of the delta's surface detracting somewhat from the pleasing aspect of the middle valley topography. Located in elevated sites to enable access, several pits (e.g. at Ess Bridge and Carrowndoon) have exposed visibly outstanding sands and gravels to travellers on the main Ballycastle-Cushendun road (A2). The removal of disused excavation machinery is recommended, especially at Drumnakeel (316400 440000), a quarry site which was at one time a good exposure of deltaic bedding. This location neighbours a souterrain, visible from the roadway. The archaeological site has no acknowledgement on 1:50,000 or 1:10,000 scale O.S. maps. It is visited regularly however as evidenced by an erosion trail which leads up the grassy bank to the site. Other archaeological features include a standing stone at (320100 437100), an impressive vantage point from which to view the valley. The rath/mound at Ess Bridge (317400 439800) appears to have been altered by the construction of a small ridge (<1m high) around its upper rim and is presumably for grazing livestock (sheep) protection, but may lead to false impressions of the feature's form once grassed over. The neighbouring pit scar detracts from its aesthetic value. The head of the valley has been afforested and apart from being a developing economic resource is the site of a pleasant and popular forest recreation park (Ballypatrick Forest Park). The standing stone location (above) could be included as an extension of the Ballypatrick forest amenities, perhaps as a walkway, as no views of the valley are possible from within the forest. The soils of the delta surfaces are of enough agricultural value to prevent complete afforestation and thus visual impairment of the topography. With increased elevation, the afforestation gives way to peat bogs and rolling topography, incised by a rock-cut meltwater gorge occupied by the A2 from Loughareema onwards. The peat is worked, but not intensively, and supports a rich flora. Loughareema is itself a notable site. The 'Vanishing Lake' is an ephemeral water body, draining away via subterranean channels leaving a curious landform and ecologic 'clean sheet' every year. Its location, overlooked by the main road, should lend itself to good accessibility. Instead the (main) road's proximity to the lakeside prohibits easy pedestrian access, which may help in its preservation by relieving visitor pressure.

Access

Management:

The existence of an observable glaciomarine delta surface in such pristine condition makes the Carey valley infill of considerable geomorphic importance. The sand and gravel facies dominate the topography of what would otherwise be a glacially overdeepened river valley with gently sloping sides. They greatly enhance relief and shelter on the valley-floor for grazing animals. The present flood plain of the Carey River is a picturesque gorge secluded from main thoroughfares and home to small brushwood and riverbank habitats. The exposure at Drumadoon is of national importance. Additional exposures are scarce and, most gravel pits are by now abandoned and vegetated. Some that are present form scars on the upper rim of the delta's surface detracting somewhat from the pleasing aspect of the middle valley topography. Located in elevated sites to enable access, several pits (e.g. at Ess Bridge and Carrowndoon) have exposed visibly outstanding sands and gravels to travellers on the main Ballycastle-Cushendun road (A2). The removal of disused excavation machinery is recommended, especially at Drumnakeel (316400 440000), a quarry site which was at one time a good exposure of deltaic bedding. This location neighbours a souterrain, visible from the roadway. The archaeological site has no acknowledgement on 1:50,000 or 1:10,000 scale O.S. maps. It is visited regularly however as evidenced by an erosion trail which leads up the grassy bank to the site. Other archaeological features include a standing stone at (320100 437100), an impressive vantage point from which to view the valley. The rath/mound at Ess Bridge (317400 439800) appears to have been altered by the construction of a small ridge (<1m high) around its upper rim and is presumably for grazing livestock (sheep) protection, but may lead to false impressions of the feature's form once grassed over. The neighbouring pit scar detracts from its aesthetic value. The head of the valley has been afforested and apart from being a developing economic resource is the site of a pleasant and popular forest recreation park (Ballypatrick Forest Park). The standing stone location (above) could be included as an extension of the Ballypatrick forest amenities, perhaps as a walkway, as no views of the valley are possible from within the forest. The soils of the delta surfaces are of enough agricultural value to prevent complete afforestation and thus visual impairment of the topography. With increased elevation, the afforestation gives way to peat bogs and rolling topography, incised by a rock-cut meltwater gorge occupied by the A2 from Loughareema onwards. The peat is worked, but not intensively, and supports a rich flora. Loughareema is itself a notable site. The 'Vanishing Lake' is an ephemeral water body, draining away via subterranean channels leaving a curious landform and ecologic 'clean sheet' every year. Its location, overlooked by the main road, should lend itself to good accessibility. Instead the (main) road's proximity to the lakeside prohibits easy pedestrian access, which may help in its preservation by relieving visitor pressure.

References (8)
Charlesworth, J.K., 1924. The glacial geology of the north-west of Ireland Proceedings of the Royal Irish Academy, vol. 36 pt. B, pp.174-314.
Gustavson, T.C. & Boothroyd, J.C., 1987. A depositional model for outwash, sediment sorces and hydrologic characteristics, Malaspina Glacier, Alaska: a modern analog of the southeastern margin of the Laurentide Icesheet Geological Society of America Bulletin, vol. 19, pp.187-200.
Hill, A.R. & Prior, D.B., 1968. Directions of ice movement in northeast Ireland Proceedings of the Royal Irish Academy, vol. 66 pt. B, pp.71-84.
McCabe, A.M. & Eyles, N., 1988. Sedimentology of an ice-contact glaciomarine delta, Carey Valley, Northern Ireland. Sedimentary Geology, vol. 59, pp.1-14.
McCabe, A.M., Carter, R.W.G. & Haynes, J., 1994. A shallow marine sequence from the Northwestern sector of the last British ice-sheet, Portballintrae, Northern Ireland. Marine Geology, vol. 117, pp.19-34.
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.
Syvitski, J.P.M., Burrell, D.C. & Skei, J.M., 1987. Fjords: Processes and Products, pp.379 Springer-Verlag, New York.
Wilson, H.E., 1972. Regional Geology of Northern Ireland. HMSO, Belfast.

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

Enlander, I., Dempster, M. & Doughty, P., 2026. Carey Valley, County Antrim, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=463. Accessed on 2026-11-06.