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 lies within the region described as the Igneous Massifs of Down and Armagh. This region consists of two igneous complexes that rise above the broken foothills of a largely Silurian basement and are separated by the fault-guided and glacially modified inlet of Carlingford Lough. To the northeast are the rounded, Tertiary granite domes of the Mourne Mountains, whilst to the southwest are the mixed Caledonian and Tertiary igneous intrusions that comprise the ring dyke complex surrounding the central mass of Slieve Gullion. Separating the two are the drumlin covered Newry lowlands and the fault-guided Newry River.
The prominent pyramidal peaks of the Mourne Mountains form a stunning backdrop to views throughout south-eastern Northern Ireland. They comprise an area of distinct steep rocky summits rising to 850m at Slieve Donard. The underlying geology is an intyrusive complex of five different granites (G1 - G5). It is a landscape of exposed, thin grass cover, rock and scree slopes. There are 12 high peaks grouped close together near the highest summit of Slieve Donard. The open mountain slopes are predominantly rough grass and heather, close-cropped by sheep. Loughs, reservoirs and rocky mountain streams occupy the steep combes and glens, which dissect the mountain ridges. Areas of blanket bog on the narrow plateau between the peaks are punctuated by small rounded loughs, the sources of the many rivers and streams that radiate from the mountains.
Morphologically, the Mournes consist of two mountain blocks. In the east, the High Mournes are found on the G1, G2 and G3 granites, whereas in the west, the Low Mournes are underlain by the G4 and G5 granites. Between the two is the col of Deer's Meadow, now largely covered by the Spelga reservoir. The col is underlain by Silurian shales and mudstones of the country rock. Outliers of this also occur high on Slieve Donard and it appears that the unroofing of the complex is both incomplete and recent in geological terms. Because of this, the major elements of the landscape are still greatly influenced by the structural characteristics of the underlying geology, in particular the prevalence of curvilinear sheet jointing that formed in response to pressure release or 'dilatation' as the overburden was removed. These joints not only contribute to the dome shaped outlines of many of the peaks, but also facilitated the past quarrying of the granite. Pressure release at a microscopic scale might also help to explain why the granites typically weather directly from large boulders into the sandy regolith or 'grus' that mantles much of the landscape, especially beneath any peat cover. A feature of the mountains are their particularly steep slopes. This is partly structural control by the granites, but is also associated with previous glacial erosion during the early part of the last glacial phase in the area. During this, the Mournes existed as an obstacle to a readvance of regional ice that flowed from the north and butted against the northern slopes and separated into two lobes around 15ka B.P. (see LCA 84). The western lobe was deflected westwards down Carlingford Lough and the eastern lobe curved around the eastern slopes of the Mournes as far south as Dunmore Head (see LCAs 73 and 74). This left the highest peaks largely ice free, although individual valleys held glaciers that are associated with the many steep-walled corries to be found in the High Mournes, including ones at the heads of the Glen and Annalong rivers. Within many of the major valleys (e.g. the Attical, Silent Valley, Annalong and Bloody Bridge) the retreat of these valley glaciers left arcuate ridges of moraine. (see below). Slope steepening was also associated with freeze/thaw action, which produced numerous rugged cliffs standing above talus (scree) deposits, and possible snow patch accumulation. Colhoun, for example, identified what he considered to be a 'pro-talus rampart in the Pigeon Rock River area that accumulated below a snow patch and now lies below a steep cliff. Other possible evidence of periglacial activity could include spreads of frost-shattered debris blanketing the upper slopes of Slieve Donard and Chimney rock Mountain, and the many summit and valley-side tors that characterise the mountains. These represent arguably the best developed suite of tors in Ireland and notable examples can be seen at Hen and Cock mountains in the west, Slieve Bearnagh in the north and Slieve Binnian in the south.
The area is generally characterised by an open, exposed, wilderness mountain landscape and its distinctive character is reflected by its designation as an Area of Outstanding Natural Beauty. The Eastern Mournes are also designated as an ASSI, as a result of their geological and physiographical features as well as heathland and upland flora. For further information on this area and the Tertiary history of Ireland, see Davies and Stephens (1978)
Pre-Quaternary (Solid) GeologyRock succession: the youngest (top) of which usually overlie the oldest (at the base). The older formations can be upside down (tectonically inverted).
Stratigraphic Table (youngest rocks at the top of the table)| Tertiary - various late intrusives, about 50 - 55 million years old |
| Tertiary - early intrusives (Mourne Granites) - about 55 million years old |
| Lower Palaeozoic - Hawick Group - about 450 million years old |
This LCA comprises the central part of the Mourne Mountains and has 25% Lower Palaeozoic Hawick Group (intruded by felsites and dolerites) in the north and south, with Tertiary Mournes Granites (G1 to G5) through the central part of the LCA (ASSI 095).
The Mourne Granites were emplaced in successive injections at two centres: LCA75 covers the boundary between the eastern and western centre. To the east of LCA75, isolated inliers of the earliest granite, G1 are seen as remnant stocks that have been enveloped by G2. The eastern granite - country rock succession can be observed at Bloody Bridge (ESCR site 94). G2 contains the unusual dark quartz crystals known from this area of the Mournes. The nature of the G4 and G5 intrusions can be elucidated in the western part of LCA75, where the remnant roof of the granite chamber is still intact as pendants of Hawick Group (with dolerite dykes). A felsitic (acid - composite) cone-sheet extends in an arc through the Hawick Group exposure on the western edge of LCA75, where it is best observed along the coast. This was a late intrusion, forming as the granite solidified, cooled and the overlying ground collapsed and cracked in a crater-like manner, allowing late molten rock to inject in a thin sheet. ESCR Sites 103 (Rocky Mountain) and 102 (Spelga Dam) occur in this LCA.
Faulting
A NE-SW trending fault forms the western boundary of LCA75. This is one of a suite of post-granite faults of this trend, in this area.
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.
Although it principally consists of an upland area stripped of drift deposits by glacial erosion, LCA 75 is characterised by a series of glaciofluvial complexes within the headwater sections of the incised valleys that drain the massif to the south and east. In the east, there is a narrow component of the coastal plain covered by the The Northeast Mournes Moraine and Raised Beach Complex.
The southwards flowing rivers that drain the Mournes contain three important glaciofluvial complexes: The Attical Valley Complex (6.5km2 in this LCA), The Annalong River Moraine Complex (2.5km2 in this LCA) and Silent Valley Complex (1.1km2 in this LCA). Although individually variable, the complexes all characteristically comprise well-preserved, cross-valley, arcuate recessional moraines. These are associated with a Late Midlandian advance through the mountains, and subsequent retreat of ice up the valleys. Those in the Annalong Valley are seen to postdate moraines of an earlier Late Midlandian phase which records the retreat of ice northward across the Mourne Plain. In the Attical region, the moraines are related to proglacial outwash in inter-moraine areas.
The Northeast Mournes Moraine and Raised Beach Complex (3.7km2 in this LCA) comprises two zones. This LCA is restricted to the southern zone that is roughly triangular in shape and extends from Ballymartin north to Newcastle and west to Ballyveagh Beg Upper. The complex consists of two main morphological elements. Recessional moraines that were linked to ice that initially advanced southwards around the eastern flank of the Mournes as far as Ballymartin. Deposition followed the lowering of the ice sheet and its retreat northwards and eastwards during the Late Midlandian. Shoreline notches cut into moraine ridges on the coastal lowlands and in the Newcastle area during late- and postglacial marine highstand are associated with spreads of beach sand and gravel. The rest of the southern zone lies in LCA 74.
The Western Mournes moraine and drumlin complex (1.5km2 in this LCA) occupies the valleys of the three southwestward flowing rivers and adjacent lowlands of the Western Mournes. The western margin of this LCA runs along the axis of the Kilbroney, Glen and the upper Shanky's Rivers, all of which contain recessional moraines associated with Late Midlandian ice retreat. The lowlands southwest of the Mournes are characterized by southeastward trending drumlins. These are related to Late Midlandian fast ice flow into Carlingford Lough, through the western valleys of the Mournes and across the lowlands to the ice limit at Cranfield Point. This probably indicates rapid downdraw of marine-based ice. Chaotically distributed hummocks and occasional kettleholes on the lower slopes of the drumlins and in inter-drumlin areas record local ice stagnation. Most of the Complex occurs in LCA 72, with minor elements in LCAs 69 and 84.
Key Elements ASSI/ASIsA small area in the southwest of the LCA touches on the CARLINGFORD LOUGH ASSI (103).
095 EASTERN MOURNES
Geologically significant in the development of the theory of pulsed granitic emplacement; the largest outcrop of Tertiary granites in the British Isles.
MOURNE COAST ASI
A small element of the ASI, but including all of the northeast coast in this LCA.
Deglacial ComplexesThe Northeast Mournes Moraine and Raised Beach Complex
The complex is important scientifically as the moraines record the retreat of the main Late Midlandian ice sheet, with frequent stillstands. Moraines in the northern section that record a readvance of ice in the area, synchronous with ice which entered Carlingford Lough from the north at around 15ka B.P.. Beach notches record the relationship between high late glacial sea levels and the retreating ice front.
Attical valley moraine and outwash complex
The complex is of importance because the ice-contact cross-valley moraines cut across and thus postdate the preserved moraines associated with the main late Midlandian retreat phase. The pattern and distribution of moraine ridges records the pattern of ice-front retreat through the mountains of readvance ice which crossed the mountains and also occupied Carlingford Lough, at the southwestern foot of the mountains;
ANNALONG RIVER MORAINE COMPLEX
The moraine complex indicates that the valley was influenced by at least two principal glacial events, of different magnitudes. The earlier, larger glaciation filled the valley and reached its mouth ca 22ka B.P.. The smaller readvance occurred during the period of climatic deterioration at the end of the Midlandian.
Western Mournes moraine and drumlin complex.
The complex is considered to be of limited scientific value as the type of cross-valley moraines occurring in the complex are common in the Mourne Mountain valleys and moraine morphology is frequently indistinct.
BLOODY BRIDGE RIVER Valley Complex (The Northeast Mournes Moraine and Raised Beach Complex)
A complex of arcuate cross-valley moraine ridges and glaciofluvial outwash contained within the Bloody Bridge valley on the eastern margins of the Mourne Mountains. The complex consists of two sets of moraine ridges and benches, that provide evidence for the decay and readvance of a valley-based glacier, outwash spreads and a glaciofluvial fan. The Bloody Bridge River complex is of good scientific value. The landforms and sediments provide a rare record in Northern Ireland of the separation of valley glacier and lowland ice masses.
Other sites/units identified in the Earth Science Conservation Review94 Bloody Bridge
Tertiary.
103 Rocky Mountain
Tertiary.
102 Spelga Dam
Tertiary.
104 Eagle Mountain
Tertiary. Mountain summits show roof of Silurian hornfels above intrusive granites of Western Mournes. Dykes intersecting the hornfels but truncated by granite can be seen.
AONBAll of the LCA lies within the Mourne AONB (1986). This designation is indicative of the scenic quality of the landscape.