The use of a cultural overlay in defining Landscape Character Areas (LCAs) means that they frequently subdivide natural physiographic units. It is common therefore for significant geomorphological features to run across more than one LCA. It is also possible in turn, to group physiographic units into a smaller number of natural regions. These regions invariably reflect underlying geological, topographic and, often, visual continuities between their component physiographic units, and have generally formed the basis for defining landscape areas such as AONBs. It is essential therefore, that in considering the 'Geodiversity' of an individual LCA, regard should be given to adjacent LCAs and to the larger regions within which they sit. In the original Land Utilisation Survey of Northern Ireland, Symons (1962) identified twelve such natural regions.
This LCA forms the northern margin of the region described as the Antrim Plateau and Glens. This upland area is dominated by a series of structural plateaux that dip gently in towards the Lough Neagh Basin. Detailed topography is largely controlled by a succession of Tertiary basalt lava flows that define successive, large-scale steps within the landscape. The plateaux are separated from each other and their frequently dramatic margins are fretted by often fault-guided, steep-sided glens. Recession of the plateaux margins has exposed underlying Mesozoic strata and, in some areas, the Palaeozoic basement. The plateaux margins are typically characterised slope failures that range from large rotational landslides to individual blockfalls.
The Ballycastle Glens are located to the east of the Causeway Coast, on the north coast. They comprise an attractive series of steep sided valleys, carved from schists, with rocky rivers in the valley bottoms. The glens are enclosed by smooth, rounded hills. Glentaisie and Glenshesk lie either side of the prominent hill of Knocklayd. The Carey River is set within a more open landscape, and has distinctive terraces associated with its channel at Ballyvoy. The high quality of the landscape is reflected by its status as an Area of Outstanding Natural Beauty. Steep slopes, long views, and attractive wooded river corridors with low lying wetland areas of sedge and alder make the area very vulnerable to change. Contained within the LCA are significant spreads of glaciofluvial sediments in the Glenshesk and Carey valleys.
In the north of the LCA, the coastal town of Ballycastle has grown around the confluence of the Tow, Glenshesk and Carey rivers. The town has experienced several major floods in the last two decades and particularly in 1990. These have been attributed to the combined effects of intense precipitation, short, steep river catchments and wet antecedent conditions. Rainfall is collected from a large upland catchment and then funnelled down narrow valleys to the coast through Ballycastle. In addition, the hydrological characteristics of the rivers appear to have changed, and moved to a flashier regime. This alteration might be related to land use change in the upper catchments where increased artificial drainage needed for mechanical peat extraction and afforestation has reduced the storage capacity of the peat cover on the Antrim Plateau.
Pre-Quaternary (Solid) GeologyThe stratigraphy of this area is made up of the mapped formations in the table, the youngest of which usually overlie the oldest.
Stratigraphic Table (youngest rocks at the top of the table)| Tertiary - Upper Basalt Formation & intrusive dykes, sills and volcanic plugs, around 55 million years old |
| Tertiary - Interbasaltic Formation - Causeway Tholeiite, about 55 million years old |
| Tertiary - Lower Basalt Formation, about 55 million years old |
| Cretaceous - Hibernian Greensand & Ulster White Limestone, around 100 million years old |
| Carboniferous - limestones and coal measures, about 340 million years old |
| Neoproterozoic (Dalradian) - Murlough Bay and Owencam formations, around 550 million years old |
The geology comprises a mix of Neoproterozoic metamorphic, Mesozoic sedimentary and Tertiary igneous rocks in faulted and unconformable contact. It includes the abandoned Ballycastle Coalfield (ASSI 147).
The NE Antrim Dalradian comprises sediments and volcanic rocks that have been buried and metamorphosed. The succession is equivalent to that exposed in Kintyre and is similar in being inverted (i.e. upside down), a product of tectonic events. In LCA119, the Dalradian succession occurs in southern strip.
The Carboniferous succession comprises lavas and limestones at the base, passing up into laterally more continuous sandstones and coals (with one correlatable limestone succession). The lavas occur in LCA120 (to the north: a thin strip) and to the northeast. The bulk of the outcrop is composed of sandstones, limestones with minor mudstones, siltstones and coals.
The Cretaceous succession includes the Ballycatle Pellet Chalk, exposed between Ballycastle Pier and Port Calliagh (possible ASSIs and ESCR sites 277 and 297).
The two Tertiary-aged basalt formations comprise a crudely-bedded succession of lava flows, columnar jointed lava flows, ash-falls and red-weathered horizons (or boles). These two formations are separated by red, palaeoweathered beds and columnar basalts (Causeway Tholeiites) of the Interbasaltic Formation (IBF).
The most significant fault in the area is the Tow Valley Fault that runs from Ballycastle Bay, southwest along the Glentaisie River and continues to the Ballymoney Basin in the southwest.
Quaternary (Drift) GeologyNorthern Ireland has experienced repeated glaciations during the Pleistocene period that produced vast amounts of debris to form the glacigenic deposits that cover >90% of the landscape. Their present morphology was shaped principally during the last glacial cycle (the Midlandian), with subsequent modification throughout the post-glacial Holocene period. The Late Midlandian, the last main phases of ice sheet flow, occurred between 23 and 13ka B.P. from dispersion centres in the Lough Neagh Basin, the Omagh Basin and Lower Lough Erne/Donegal. The clearest imprint of these ice flows are flow transverse rogen moraines and flow parallel drumlin swarms which developed across thick covers of till, mostly below 150m O.D. during a period that referred to as the Drumlin Readvance. At the very end of the Midlandian, Scottish ice moved southwards and overrode parts of the north coast. Evidence for deglaciation of the landscape is found in features formed between the glacial maximum to the onset of the present warm stage from 17 and 13ka B.P. - a period of gradual climatic improvement. Most commonly these are of glaciofluvial and glaciolacustrine origin and include: eskers, outwash mounds and spreads, proglacial lacustrine deposits, kame terraces, kettle holes and meltwater channels (McCarron et al. 2002). During the Holocene, marine, fluvial, aeolian and mass movement processes, combined with human activities and climate and sea-level fluctuations, have modified the appearance of the landscape. The landforms and associated deposits derived from all of these processes are essentially fossil. Once damaged or destroyed they cannot be replaced since the processes or process combinations that created them no longer exist. They therefore represent a finite scientific and economic resource and are a notable determinant of landscape character.
The drift geology map for this LCA shows it to be predominantly underlain by Late Midlandian till associated with the large ice mass that that moved northwards from a centre in the Lough Neagh Basin. In the east of the area this till was subsequently overridden by so-called 'Scottish ice' that advanced southwards towards the very end of the last episode in Northern Ireland. The limit of this advance is marked by the extensive 'Armoy Moraine Complex'. The final downwasting and retreat of the Lough Neagh ice was associated with the creation of ice-marginal deglacial complexes below the ice free Antrim Plateau, most notably in the Glenshesk and Carey Valleys. These complexes are described below.
The Armoy Moraine Complex (0.8km2 in the southwest of this LCA) comprises a dominant feature of the local landscape that marks the southern extent of an advance of Scottish ice, which pushed sediments that had previously been deposited by an ice mass centred on Lough Neagh. The Armoy moraine is up to 4km wide, extends about 20km, northeastwards from Ballymoney into the Tow River valley and consists of large continuous ridges. Sediments within the moraine are typical of lake deposits, probably laid down by meltwater emanating from an ice body centred on Lough Neagh. Exposures have shown that these deposits were then pushed from the northwest by an ice body of Scottish provenance. Exposures have also shown that the top of the feature has been planed off. Together with the distribution of streamlined landforms, this indicates that retreat of Scottish ice was followed by a northward advance of Lough Neagh-based ice.
The Carey Valley Delta Complex (5.3km2 in this LCA) consists of variable stratified sands and gravels occur along the axis of the Carey Valley as a northward thickening wedge of sediment that overlaps LCAs 118 and 119.
The Glenshesk Valley Complex (2.6km2 in this LCA) is contained in the 'rock-bounded', 10km long by 1km wide and 200 m deep Glenshesk valley to the southeast of Ballycastle at the northern margins of the Antrim Plateau. As such it overlaps LCAs 118 and 119. Glaciofluvial deposits in Glenshesk are located mainly in the middle part of the valley and consist of cross-valley moraine ridges, cross-valley glaciolacustrine ridges, outwash fans and outwash terraces associated with meltwater draining westward and northward from successive ice margin positions located across the valley. Morphological evidence suggests that these forms are associated with deposition from ice masses that decayed southeastwards from a maximum western extension along the Inver Burn valley towards higher ground to the east and southeast during the last deglacial cycle.
Finally, ribbons of alluvial deposits mark the floodplains of the largely fault-guided present-day drainage system. These lead down in Ballycastle to an area of blown sand behind the coastline.
Key Elements ASSI/ASIs147 BALLYCASTLE COALFIED (limited coverage in east of LCA).
Ballycastle Coalfield is the best exposure of a coalfield sequence in Ireland. It contains a series of Carboniferous sedimentary rocks (335-330 million years old) with contemporary lavas and younger Tertiary igneous rocks (60 M.y.). The sedimentary rocks were deposited in a shallow marine bay which gradually developed into a vegetated coastal swamp subject to periodic flooding by the sea. The vegetation was preserved as seams of coal. Fossils that have been found include goniatites (shellfish), fish remains, giant clubmosses and arthropod insects. The Tertiary dykes have metamorphosed the carboniferous shales to produce porcellanite and a range of minerals. The site also contains evidence of early industrial activity: the coals and iron ores were mined between the 16th and 19th centuries.
CAREY VALLEY ASI
Approximately 50% of the ASI lies in this LCA, see below.
Deglacial ComplexesARMOY MORAINE COMPLEX
The moraine is of great importance in reconstructing the chronology of ice front oscillations towards the end of the deglacial cycle and understanding the complexity of deglacial processes. Limited aggregate extraction perhaps reflects the fact that many of the sediments within the moraine are of fine-grained sands and silts of lakebed origin. The pristine condition of the landform suggests that at least this part of the moraine should be protected with regard to controls on aggregate extraction.
Carey Valley Delta Complex
The Carey Valley delta is a site of excellent scientific importance within the context of Northern Ireland and records a high relative sea level of approximately 100m O.D. This fact is of extreme value in the reconstruction of Irish Sea basin conditions upon deglaciation of the coastal shelf. It indicates significant downwarping of the Irish coast at this location.
GLENSHESK VALLEY COMPLEX
The Glenshesk valley has good scientific importance because the moraine ridge and outwash terrace associations in the valley are similar to classical models of phased retreat and decay of a valley ice lobe. The retreat pattern of the ice lobe in the Glenshesk valley also indicates continual ice pressure from the highlands to the east and southeast during the deglacial cycle. This indicates that during the deglacial cycle the Antrim plateau was glaciated by ice possibly associated with an ice dome located to the east or ice moving northwards along the coast.
Other sites/units identified in the Earth Science Conservation Review277 Port Calliagh - Ballycastle
Mesozoic and Cretaceous. Quality exposures of type sections for Port Calliagh Chalk and Ballycastle Chalk Members of Ulster White Limestone Formation. Also youngest Cretaceous strata in Northern Ireland.
297 Ballycastle
Palaeontological. Access and exposure of Ballycastle Pellet Chalk. Contains significant and diverse fossils, especially foraminifera.
AONBA limited area in the west of this LCA lies within the Causeway Coast AONB (1989), but most of it lies in the Antrim Coast and Glens AONB (1988). These designations are indicative of the scenic quality of the landscape.