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 Uplands and Drift Covered Lowlands of Down and Armagh. The generally subdued relief associated with the underlying basement complex of highly folded Palaeozoic strata provides the unity of this region. Relative relief is provided in the north by the Silurian hills that overlook the lower Lagan Valley, The Newtownhamilton Plateau in south Armagh, the Caledonian igneous complex of Slieve Croob and the structural depression that underlies and defines Strangford Lough. Below ca 350m, there is an almost complete mantle of drumlins forming an internationally acknowledged type example of a 'drumlin swarm'.
The Mourne Foothills landscape wraps around the northern fringes of the massive summits of Slieve Croob and the Mourne Mountains. The area includes the town of Castlewellan which lies between these two major upland areas at a height of 100 m above sea level. The characteristic rugged scenery, which includes some distinctive hill summits, rocky outcrops and patches of gorse, has been moulded from intrusive igneous rocks, primarily granites. Quarries are present, both working and disused and elevated points, such as White Hill, give dramatic views over the surrounding lowland landscapes of the Newcastle Valleys and the Quoile Valley Lowlands. The landscape is in particularly good condition and much of it is designated as an Area of Outstanding Natural Beauty in recognition of its scenic importance. In the south of the LCA, the landscape contains significant glaciofluvial deposits of the Northeast Mournes Complex that has produced an undulating landscape is typical of the rolling moraine and drumlin dominated topography of lowland County Down. The moraine ridges have been little scarred by quarrying. The few pits in the area are no longer worked, are mostly overgrown, and are well hidden from casual view This area is considered to have a good aesthetic rating and the upper limits of the area contrast with the heather bedrock and boulder deposits of the lower slopes of the Mourne massif.
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. 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 million years old |
| Tertiary - Mourne Granites - about 55 million years old |
| Tertiary - early intrusives |
| Late Caledonian Newry Complex Intrusives - about 420 million years old |
| Ordovician (predominant) - Gala Sandstone, Hawick Group - about 450 million years old |
The area has Slieve Croob at its northern area with a strip to the coast of Dundrum Bay in the southeast. Comprises 60% Gala and Hawick groups (Lower Palaeozoic), 30% Mourne granite and the remainder being a variety of Caledonian and Tertiary intrusives.
Lower Palaeozoic greywacke sandstones and shales dominate the southeastern part of the area with one outcrop in the northwest. The greywackes are of sandstone grade and vary from a few centimetres to a few metres in thickness with a large proportion of rock fragments. The greywackes are commonly quarried as a source of aggregate; they are interbedded with thinner beds of siltstone or mudstone, commonly arranged as fining-up cycles. Minor conglomerates and volcanic ash-beds (or bentonites) occur.
Slieve Croob, in the northern part of LCA84, is composed of Caledonian (probably Devonian age) Newry Complex diorite. Foliated granodiorites are exposed at Ballymagrehan Quarry (ESCR Site 416). This is a unique exposure by virtue of location and rock age. The eastern outcrop contact between Gala Group greywackes and Slieve Croob diorites has formed hornfels metamorphism of the country rock greywackes. The Newry succession is also exposed in this LCA at of Ardglass (ESCR Site 413).
Tertiary-aged dolerite and felsite dykes occur throughout the area. The Mourne Granites were emplaced in successive injections at two centres: LCA84 covers the the first granite (G1) of the eastern centre with a small part over the later, western centre to the south.. In the south of LCA84 pink outer granites (G4) enclose a later, fine-grained microgranite or granophyre (G5).
A cone-sheet extends in an arc through the Hawick Group exposure on the southern edge of LCA84. 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.
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 was centred on the Lough Neagh Basin. However, being in the lee of the Slieve Croob upland, it would appear that sediment supply was relatively limited. Thus, whilst there are drumlins that can be used to infer the direction of ice flow, there are also many drift free areas that were scoured and moulded by the overriding ice. Although most drumlins in Northern Ireland are composed of glacial till or tills, a small number are 'drumlinoid features' are rock-cored and some are composed of sand and gravel. Where drumlins are rock cored there may have been significant frost shattering prior to their shaping by ice flow. It is possible therefore to see tails of shattered debris within till leading away from the feature in the direction of flow (Davies and Stephens 1978). It is generally accepted that most of the drumlins of Northern Ireland were formed by deposition beneath fast flowing ice. In the majority of cases this has resulted in a thick layer of Upper (younger) Till overlying a core of Lower (older) Till. This pattern has been observed across Northern Ireland, apart from a limited area in the north of County Down. The precise temporal relationship between the two tills has not been definitively resolved, but Davies and Stephens (1978) refer to an organic layer between the tills in County Fermanagh that has been dated at 30 500 ± 1170/1030 years B.P. and shelly material between the tills on the Ards Peninsula dated at 24 050 ± 650 years B.P.. However, these deposits only indicate that the Lower Till is older than the dates obtained.
In the south of the LCA, during the last glacial phase of the Midlandian 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.. 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). As a consequence, on the northern margin of the Mournes, a variety of deglacial deposits and landforms were created when the ice finally retreated from the mountain front. These comprise two deglacial complexes.
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 Northeast Mournes Moraine and Raised Beach Complex comprises two zones. This LCA is restricted to the irregularly shaped northern zone and has a southern limit that follows the indented outline of the mountains from near sea level at Newcastle to the northwest shoulder of Spelga Mountain. The deposits are mainly a series of moraines which trend sub-parallel to the mountains and reflect topographic controls by bedrock highs. The morainic belts were deposited following the early part of the last glacial phase in the area. The moraines record the final retreat of Late Midlandian ice towards its source region in the Lough Neagh Basin and front the drumlin swarms of northern County Down.
Key Elements ASSI/ASIs089 Murlough (part coverage)
A coastal complex exhibiting a range of gravel ridges, re-curved spit, dune systems, palaeosols and contemporary beach processes dating from between late glacial and modern times. This gives rise to an extensive range of coastal habitats, including scarce vegetation communities and rare plant species.
095 EASTERN MOURNES (part coverage)
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, in the southeast of the LCA.
Deglacial ComplexesWestern 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.
The 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..
Other sites/units identified in the Earth Science Conservation Review413 Ardglass
Caledonide Igneous Complexes. Access to quality exposure of ultramafic-intermediate complex of Newry igneous Complex.
416 Ballymagreehan Quarry
Caledonide Igneous Complexes. Access to foliated granodiorite, part of NE pluton of Newry Igneous Complex.
AONBApart from its northeast corner, all of this LCA lies within the Mourne AONB (1986).
This designation is indicative of the scenic quality of the landscape.