ESCR - Armoy

Earth Science Conservation Review

Summary Full report
Armoy	Antrim

Site number:	465
ESCC:	IS
Locality Type:	Inland exposure	Status:	TBC
Grid Reference:	C9529,C978317,D067328,D108391 End(s) of linear site, Not Entered
Google maps:	55.09962,-6.51176
County:	Antrim	Council area:	Causeway Coast & Glens Borough Council
Period:	Quaternary

Site Description
Highlights:
The Armoy morainic complex has traditionally been associated with a major readvance of Scottish ice into North Co. Antrim during the final stages of the last glaciation (Stephens et al., 1975; Creighton, 1974). Temporary exposures along the Ballymoney ring-road indicate that this part of the feature is composed of glaciotectonically disturbed proglacial deposits. Structurally, the high points of the ridges are linked with shear planes, though the tops of the sequences are truncated abruptly (Shaw and Carter, 1980). Streamlined ridges (NW-SE) occur on both sides of the moraine which suggest that the feature was overridden by ice of inland origin. The scientific importance of the feature therefore hinges not only on its precise origin but also on its stratigraphic relationship to major ice sheet events during the Late Devensian in north Co. Antrim. In a wider context these interpretative considerations are critical for ice-sheet reconstructions at the margins of the last ice sheet especially regarding ideas on rapid environmental changes, dynamic changes in ice marginal configuration and ice sheet surging. The well defined zones of morainic ridges form a dominant feature along the trend of the Tow valley fault which occupies a topographic low. Aesthetically the ridges are a dominant skyline feature from viewpoints to the north and south of the complex. The final glacigenic landscape is intact with only a few small quarries though this is probably a function of the presence of fine-grained sands and silts together with diamicts and the absence of economically workable sequences of washed sands and gravels.
Description:
The morainic complex is sited within a major NE-SW structural low controlled by the Tow valley fault and underlain mainly by Tertiary basalts. Some lignite sequences occur within structurally controlled basins around Ballymoney. The complex consists of large fairly continuous ridges which can be traced as topographic highs for 21km north eastwards from Ballymoney to Ballycastle. At a maximum the morainic belt is 4km in width but is generally around 3km. It decreases in altitude and topographic complexity while also narrowing in width northeastwards. The feature does not occur to the west of Ballymoney where streamlined forms dominate. The moraine can be subdivided into a series of well-defined ridges: 1. Seacon Ridge This ridge to the northwest of Ballymoney occurs as a prominent landscape feature immediately to the west of Garry Bog (295000 429000). It has gentle slopes with rounded to streamlined crests and is up to 83m O.D. There are no strongly developed ridge crests or exposures available though the soil profiles suggest fine grained sediments predominate. 2. Ballymoney/Stranocum Ridge This is the most southerly ridge, is up to 73m O.D., and consists of at least three major WSW/ENE ridge crests. It is 1.5-2km in width and 9km in length and is bounded on the south side by slopes fashioned by glaciofluvial erosion. The main northward slopes are draped on their lower flanks by the post-glacial infill of Garry Bog. Ballymoney town sits on the western margin of the ridge and the eastern margin of the ridge is trenched by the meltwater channel of the present Bush River at Stranocum. Shaw and Carter (1980) described a section at right angles to the crest of the moraine from the ring-road cuts at Drumard (296000 427500). Up to 60m of stratified deposits were exposed along a N-S section with a minimum thickness of 26m proved by borehole records (Shaw and Carter, 1980). The observed sequence consists of poorly-stratified, coarse-grained gravels, laminated silts/clays, massive silts, cross-bedded sands and diamict. Contacts between lithological units are generally sharp, with beds dipping at between 15° and 60° towards 300-320° N. The entire section is deformed by thrust planes rising to the ESE and several high angle reverse faults and numerous small scale faults. Overturned folds are closely associated with the major thrust plane. The gravel lithologies are predominately basalt clast dominated with a minimum amount of chalk, schist and quartzite. Shaw and Carter (1980) suggested that the numerous igneous and metamorphic erratics were derived from the Tyrone igneous complex to the southwest. The upper surfaces of the deformed sedimentary packages are truncated along their upper surface. 3. Dervock/Armoy Ridge This ridge complex can be traced for about 15km from Dervock (297800 231700) east to Armoy (306700 432800) and then northeastwards to Broombeg (310800 439100). The ridge is about 1km in breadth and rises to 51m O.D. at Dervock. Eastwards it rises to 99m O.D. at Mullaghduff (305700 433700). Northeast from Armoy it is less continuous and consists of low relief mounds separated by numerous meltwater channel scars. Distinct terraces occur along the Tow River especially around Cape Castle. Ridge crests are composite with at least four subparallel forms around Carncullagh (298000 431400) though the gravelly exposures around Furze Cottage (299500 431200) are mostly overgrown. These old pits contain numerous granite, flint quartzite and schist erratics with basalt predominating.
Importance:
The Armoy morainic complex is the most extensive push moraine known in N. Ireland and demonstrates many of the problems encountered when assessing the importance of glacigenic landforms. This landscape complex is unique in the following ways: A) Basically it demonstrates stratigraphic complexity created by glaciotectonics as the ice flow from Scotland deformed essentially lacustrine sediments. B) Its location demonstrates variable ice sheet activity and relative strengths of Irish and Scottish ice along the northwestern sector of the last British ice sheet. This observation is critical in future modelling of the last British ice sheet and it remains to be seen whether ice sheet variations are due to climatic forcing or internal ice sheet mechanisms. This is of national importance. C) Morphologically this is one of the largest push moraine systems in the British Isles and seems to represent a major surge of the late Devensian ice sheet. Again this is of national importance and will be of immense scientific interest. D) The model outlined above describes the likely events which occurred through the full significance of these in terms of ice sheet history is poorly constrained in time. Future dating of these and comparisons with other marginal sectors of the ice sheet will provide critical evidence for future modelling of the last ice sheet in Great Britain.
Interpretation:
It is difficult to pinpoint the precise source of the granitic erratics contained within the complex. Contrary to Shaw and Carter (1980) the suite of erratics are best explained by an ice movement from the northeast crossing Dalradian, Lower Carboniferous, Cretaceous and Tertiary outcrops. Also the absence of this suite of erratics in tills to the south of the moraine suggests derivation from ice of Scottish origin. The contrasting lithologies at Drumand are typical of proglacial sedimentation in a lacustrine setting. Extensive thrusting and folding of this sequence can best be explained by ice marginal pressure from the WNW. Therefore the stratigraphic geometry of the sequence reflects the development of a proglacial lake along the Tow valley depression impounded between Scottish and Irish ice-sheets. The main sediment input records sedimentation along the margins of a Scottish ice-sheet to the north which advanced across its proglacial sediments creating a series of large ice pushed ridges. The moraine has the form of a series of overlapping push ridges. The positions of ridge crests are probably controlled by the position of major thrust planes. The southern margin and major breaks along the margins of the complex are associated with oversteepening and later meltwater erosion. The abrupt planar truncation of the upper part of the sequence described by Shaw and Carter (1980) demonstrates that post-depositional erosion occurred and the complex was overridden by ice. The presence of drumlins with the same orientation on higher ground to the north and south of the moraine support this hypothesis. The latter was the last major ice sheet event in this area and is recorded by numerous northwest/southeast striae, and streamlined rock ridges and drumlins from Ballymena to the north coast and along the Bann valley. This ice mass ended on the continental shelf (Mc Cabe, Carter and Haynes, 1994). To the west of Ballymoney there is no topographic expression of any moraine and drumlin fields dominate. This pattern is further evidence of an erosive ice flow northwestwards along the Bann valley which post dates deposition of the morainic sediments. The following sequence of ice-sheet events during the Late Devensian is strongly suggested by the stratigraphic and morphological evidence outlined above: 1) Ice advance from western Scotland southwards into north Antrim and northwards from the Lough Neagh basin. 2) Development of a large proglacial lake along the Tow valley depression. Thick sedimentary sequences developed in the water body from point sources along the ice sheet margins. 3) Ice pushed ridges were created by ice push from the northwest associated with the maximum southern extent of Scottish ice. 4) After the Scottish ice retreated, Irish ice advanced across the moraine sediments and streamlined the topography on both sides of the moraine. There is evidence that the glaciotectonic structures are abruptly truncated and parts of the ridges are streamlined. 5) Modification and oversteepening of moraine by proglacial meltwater as the Irish ice melted and decayed towards the original centres of ice formation farther south. 6) Development of post-glacial bogs and alluviation in hollows left by the ice e.g. Garry Bog.
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
Relations:	Glacial feature, Glaciotectonic
Geomorph:	drumlin, moraine ridge

Access
Management:
There are very few noticeable gravel quarries within the entire complex. Over an area of about 30km2 only three quarries are recorded (Furze Cottage, 2km ESE of Dervock, and two small pits NE of Armoy). Possibly the presence of clays, diamicts and the highly variable composition of the feature do not favour commercial quarry operations. The glacigenic morainic ridges are intact. Their contribution to landscape diversity in this area basically centres on the continuity of ridge forms and general sweep of the complex from Ballymoney northeastwards to the outskirts of Ballycastle. Specific aesthetic attributes include: 1) The ridges are located along a tectonic depression along the Tow valley fault. The underlying solid rock rises to the north and south and these bordering zones are characteristically combinations of fairly monotonous subparallel streamlined rock ridges and rock cored drumlins. 2) The moraine forms a skyline feature along most of its length which is readily seen from the road network up to 5km away. 3) At the north eastern limit of the moraine meltwater channels parallel the feature along the Tow valley forming a dissected landscape and a series of flat terraces along the lower slopes of Knocklayd (311500 436400). The field patterns and agriculture on these deposits contrasts markedly with those on the rising slopes of Knocklayd. These contrasts provide local diversity both in terms of geomorphology and densities of trees. The channel at Kilcrue Cross (308600 438200) for example provides a well-wooded glade with a wide range of woodland ecotypes. 4) The general orientation of the ridges in the western part of the complex are juxtaposed with deep, inter-ridge hollows. The latter are important sites for post-glacial alluviation and bog development such as Garry Bog. The ridge's orientation also controls the present course of the upper Bush River, which bisects the ridges south of Livery Hill (301900 429800). It is likely that the preglacial upper Bush flowed north from Armoy to Ballycastle. Its deflection eastward to Dervock is a result of moraine blocking north of Armoy.

Access

Management:

There are very few noticeable gravel quarries within the entire complex. Over an area of about 30km2 only three quarries are recorded (Furze Cottage, 2km ESE of Dervock, and two small pits NE of Armoy). Possibly the presence of clays, diamicts and the highly variable composition of the feature do not favour commercial quarry operations. The glacigenic morainic ridges are intact. Their contribution to landscape diversity in this area basically centres on the continuity of ridge forms and general sweep of the complex from Ballymoney northeastwards to the outskirts of Ballycastle. Specific aesthetic attributes include: 1) The ridges are located along a tectonic depression along the Tow valley fault. The underlying solid rock rises to the north and south and these bordering zones are characteristically combinations of fairly monotonous subparallel streamlined rock ridges and rock cored drumlins. 2) The moraine forms a skyline feature along most of its length which is readily seen from the road network up to 5km away. 3) At the north eastern limit of the moraine meltwater channels parallel the feature along the Tow valley forming a dissected landscape and a series of flat terraces along the lower slopes of Knocklayd (311500 436400). The field patterns and agriculture on these deposits contrasts markedly with those on the rising slopes of Knocklayd. These contrasts provide local diversity both in terms of geomorphology and densities of trees. The channel at Kilcrue Cross (308600 438200) for example provides a well-wooded glade with a wide range of woodland ecotypes. 4) The general orientation of the ridges in the western part of the complex are juxtaposed with deep, inter-ridge hollows. The latter are important sites for post-glacial alluviation and bog development such as Garry Bog. The ridge's orientation also controls the present course of the upper Bush River, which bisects the ridges south of Livery Hill (301900 429800). It is likely that the preglacial upper Bush flowed north from Armoy to Ballycastle. Its deflection eastward to Dervock is a result of moraine blocking north of Armoy.

References (4)
Creighton, J.R., 1974. A study of the late Pleistocene geomorphology of north Central Ulster (Thesis) Unpublished PhD Thesis, Queen's University of Belfast.
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., 1980. Late-Midlandian sedimentation and glaciotectonics of the North Antrim End Moraine Irish Naturalists Journal, vol. 20 pt. 2, pp.67-69.
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.

Record type:	ESCR report
Entered by:	E M Porter
Last updated:	7 Jan 2005

Enlander, I., Dempster, M. & Doughty, P., 2026. Armoy, County Antrim, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=465. Accessed on 2026-11-04.