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 Scrabo landscape is an area of flat, open land situated at the head of Strangford Lough. It incorporates the town of Newtownards, the distinctive steep rocky outcrop of Scrabo Hill and the meandering tranquil landscape of the Comber Estuary. Scrabo Hill rises dramatically out of the sandstone plain, acting as a focus and landmark for miles around; this is reinforced by the tower that marks the highest point. A number of sandstone quarries expose sections of the underlying rock through the vent and sills of this impressive landform. Scrabo Hill's designation as a Country Park enhances its recreational potential and panoramic views from the top are breathtaking.
Orford (in Whalley et al. 1985) has described the coastal lowlands around Strangford Lough as a mixture of glaciomarine shelf sediments with a superimposed two unit drumlin cover, lying on a low undulating basement of Silurian greywacke and mudstones. Strangford Lough is tidal with a distinctive straight east coast and a highly irregular west coast morphology. The lough contains numerous drowned drumlin islands that have been removed completely from the eastern shore to leave remnant shoals or 'pladdies'. On the western shore the drumlin islands are largely retained and linked by limited shoreline deposition. The difference between the lough shores is because of the prevailing southwesterly waves that vigorously attack the eastern shore, whilst leaving the western shore largely untouched. There are extensive intertidal mud and sand flats in the north of the lough that act as sinks for most of the sediment derived from the erosion of the east coast. Sites such as those at Rough Island and Ringneill Quay (LCA94) have been important in documenting post-glacial sea level fluctuations. In particular, McCabe and Knight (in Knight 2002) have observed that at the head of Strangford Lough there are well defined late- and post-glacial wave-cut terraces at around 20m O.D..
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 - various intrusives, about 55 million years old |
| Triassic - Sherwood Sandstone Group, about 230 million years old |
| Permian - Enler & Belfast groups, about 260 million years old |
| Upper Palaeozoic - Carboniferous - about 350 million years old |
| Lower Palaeozoic - Ordovician (predominant) - Gala Sandstone, about 450 million years old |
The area predominantly comprises the Triassic Sherwood Sandstone Group. Northeastern tip covers the Lower Palaeozoic, southern area the Permian and Carboniferous Castle Espie succession, the remainder being Tertiary intrusives.
The northern 15% of LCA101 is underlain by Lower Palaeozoic greywacke sandstones and shales. 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 and a fine-grained matrix. 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. Similar strata are found at the southern end of LCA101.
The southern part of LCA101 encroaches onto Carboniferous rocks. These comprise fossiliferous limestones and thin shales. This is a unique location for rocks of this age which are in faulted contact with older strata at the western limit to the Carboniferous sediments.
Permian
Enler & Belfast Group strata rest unconformably and also in faulted contact with various older rocks in the south of LCA101. The estuary extending from Comber to Strangford Lough has eroded preferentially into Enler Group strata. The Enler Group comprise red-brown sandstones, conglomerates, siltstones. The Belfast Group comprise mudrocks the topmost 1-4 metres of the Belfast Group comprises the Magnesian Limestone Formation, a dolomitic, fossiliferous limestone.
Triassic
Sherwood Sandstone Group sandstones comprise red, purple and brown cross-stratified sandstones, siltstones with minor clay beds and partings. The sandstones are exposed in the quarries of Scrabo Country Park (ASSI 091), where they were formerly extracted for building stone. Here, a Tertiary sill and dykes have caused local mineralisation and hardening of the sandstones.
Tertiary
Tertiary dolerite dykes occur throughout the area with most oriented NW-SE. A Tertiary dolerite sill, intruded into Sherwood Sandstone, caps the crag and tail of Scrabo Hill (ASSI 091).
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 of the LCA identifies a cover of Midlandian over much of the area, apart from limited drift free area around Scrabo and in the north where the land rise towards Bangor. In his study of drumlins in north Co. Down, Hill (1971) identified drumlins across most of the region that consisted of a thick layer of Upper (younger) Till overlying a core of Lower (older) Till. This Younger Till was associated with the large ice mass that was centred on the Lough Neagh Basin and ice that flowed southeastwards from an ice divide that lay approximately SW-NE along the line of the north Belfast Hills. The exception to this combination off tills can be seen in the north of this LCA, where Hill observed drumlins aligned approximately north to south that are composed only of Lower Till and that formed in response to ice that flowed southwards from the North Channel. 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.
Superimposed on the tills are areas of glaciofluvial deposits either side of the Scrabo upland that derive late-glacial deposition by meltwater along the Enler Valley between Belfast and Comber - the so-called 'Dundonald Gap'. Smith et al. (1991) describe these deposits as mounded outwash that consists of laminated sand and gravel with subordinate red clays. The map also identifies extensive 'reclaimed' land around the head of the Lough and, more interestingly, it shows a series of raised beach deposits in the south of the LCA. The most notable of these are to be found at Rough island. Rough Island, southeast of Comber, is an erosional remnant of the flat upper terrace surface of a wave-cut terrace at about 20m O.D.. The drumlins in this area have also been draped by a red marine clay that feathers out at a height of 16m O.D.. This clay is similar to that observed at Roddans Bay on the outer Ards Coast (LCA 99), but it is better preserved in the more sheltered environment of Strangford Lough.
Key Elements ASSI006 STRANGFORD LOUGH PART 1
Extensive mudflats, sandflats, saltmarsh and rocky intertidal shore (including Strangford Narrows)
034 STRANGFORD LOUGH PART 3
Extensive mudflats, saltmarsh and other types of shoreline habitat, including The Dorn (NNR), a unique and exceptionally important site for intertidal flora and fauna.
091 SCRABO
Exposure of the Triassic Sherwood Sandstone Group including Chirotherium and other reptilean footprints and scorpion tracks, together with evidence of Tertiary vulcanism.
AONBSignificant elements in the centre and south of this LCA lie within the Strangford lough AONB (1972). This designation is indicative of the scenic quality of the landscape.