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 Newry Basin is a large scale rolling drumlin landscape situated between the Ring of Gullion and the Mourne Mountains. The area is drained by tributaries of the Newry River that flow in attractive river valleys. The drumlins are orientated north-northwest to south-south-east. To the southeast, the drumlins are displaced by broader ridges separated by narrow, flat-bottomed valleys with ribbon loughs and bogs such as Derryleckagh Lake and Greenan Lough. To the south of Newry, the Newry River flows in a dramatic, steep sided narrow valley. There are occasional panoramic views of the Mourne Mountains from the tops of the drumlins. The landscape seems open and exposed on ridge-tops and enclosed and sheltered within the valleys. On the southern coastal plain of the LCA, moraines add topographic diversity to an area where the visual dominance of the Mourne mountains decreases rapidly westward and the drumlins around Rostrevor continue the trend of declining hilltop altitude towards the west and south, their clustered pattern and streamlined morphology contrasting with the isolated valley divides of bedrock highs. The most sensitive landscapes are the attractive river valleys, loughs and marshes.
Carlingford Lough has been described by Orford (in Whalley et al. 1985) as a low energy estuary filling a structurally controlled (NW-SE fault) glacially scoured depression. The estuary mouth is shallow due to a ridge of carboniferous limestone which allows wave focusing of south westerly storms onto the northern shoreline where erosion of the glacigenic Kilkeel plain has left a number of bays dominated by gravel beaches.
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 intrusives, about 60 - 50 million years old |
| Lower Basalt Formation - about 50 million years old |
| Late Caledonian Newry Complex Intrusives - about 400 million years old |
| Ordovician (predominant) - Moffat Shale, Gala Sandstone, Hawick Group - about 450 milion years old |
The area comprises 50% Newry Complex intrusives, 40% Lower Palaeozoic (predominantly Ordovician) greywacke sandstones and shales, the remainder being Tertiary Lower Basalt Formation and dykes.
Late Caledonian
The outcrop contact between greywacke and granodiorite is well exposed at Goraghwood Quarry (ESCR Site 420).
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 an area largely underlain by a late Midlandian till that constitutes most of the drumlins in the area and was deposited by ice that flowed southwards from a centre in the Lough Neagh Basin. Within Northern Ireland drumlins take a variety of forms; some are rounded in plan, although the majority are elongated in the direction of ice flow. Some have sharp crests, whereas others are more whaleback in profile. Although most drumlins 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 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.
It can be argued that an equally important component of any 'drumlin landscape' are the similarly numerous inter-drumlin hollows. The majority of these hollows would have held open water from local runoff at the end of the Pleistocene. Whilst some continue to exist as isolated small loughs, many have now been infilled by sediment washing off the surrounding drumlins. This has created typically flat-bottomed, marshy areas between the drumlins that are subject to seasonal inundation. Much of the infilling probably occurred early in the Holocene, as the landscape adjusted to increasingly temperate conditions. However, erosion may also have been accelerated in historical times, when rural population densities were considerably higher and much of the lowland landscape of Northern Ireland was more intensively cultivated. Whatever the stimulus for erosion and deposition, the sediments within these hollows typically contain an important record of local environmental change.
Running north to south through the LCA is the Poyntz Pass glacial drainage channel. This channel formed during the deglaciation of the Lough Neagh lowlands, when there was a period when downwsting ice occupied the Lower Bann valley and prevented the northwards drainage of the proto-Lough Neagh. Lake levels then rose until an alternative outlet was found to the south via Pontz Pass and Newry to Carlingford Lough (Davies and Stephens 1978). McCabe and Hirons (1986) have described this drainage channel as having similarities to a tunnel valley system, in which sand cored drumlins occur within the channel system itself and are flanked by large rock drumlins west and east of the channel.
The deglaciation of the area is further marked by the occurrence in the southeast of the LCA of elements (2.2km2) of the Western Mournes Moraine and Drumlin Complex. The valleys of the Ghann, Moygannon and Kilbroney Rivers, as well as the Glen River and the upper Shanky's River, all 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. Other areas of the Complex occur in LCAs 72, 75 and 84. The drift map for the LCA clearly shows the post-glacial raised beach deposits that underlie much of the narrow coastal plain between Warrenpoint and Rostrevor. Interestingly, it also shows an area of raised marine deposits beneath the centre of Newry. If confirmed, these could have implications for the interpretation of the Holocene history of thecoastal zone. One possibility is that they could represent a mid-Holocene transgression associated with rising sea level that extended the estuary of the Newry River much further inland. This area would clearly benefit from further research.
Key Elements ASSI103 CARLINGFORD LOUGH
The limestones of Carlingford Lough were deposited in a shallow sea basin during the Carboniferous period 339 million years ago. They contain numerous fossils, such as brachiopods and solitary corals. Moraines and deposited sediments provide evidence of the movement of ice sheets and glaciers. The site supports a range of unusual and rich littoral communities, including sheltered sands, muddy sands, muds and boulder shores. It exhibits a good natural transition from lower shore communities, through upper shore saltmarsh to fen vegetation. Mill Bay supports the largest intact block of saltmarsh in Northern Ireland.
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.
Other sites/units identified in the Earth Science Conservation Review420 Goraghwood Quarry
Caledonide-Igneous. Outcrops show relationships between contact metamorphosed Silurian country rocks and a variety of granodiorites in middle pluton of Newry Igneous Complex.
418 Gransha
Caledonide-Igneous. Access to quality outcrops of strongly foliated granodiorite. Part of NE pluton of Newry Igneous Complex.
Croreagh Quarry
AONBsThe southwestern margin of the LCA overlaps the boundary of the Slieve Gullion AONB (1991), whereas the southeaster margin overlaps and incorporates pat of the Mourne AONB (1986). This designation is indicative of the scenic quality of the landscape.