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 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 Tardree and Six Mile Water Slopes wrap around an area of high basalt moorland which includes the summits of Carn Hill, Big Collin, Wee Collin, Tardree Mountain and Douglas Top. The area lies between the high ground of the Tardree Upland Pastures and the Three and Six Mile Water Valleys. It is characterised by an area of relatively degraded undulating farmland with overgrown, leggy hedgerows and rushy pastures. The uneven topography results in an irregular field pattern. The steeper slopes, on the edge of the basalt moorland to the north, become progressively more wooded towards the east. The western limb of the LCA that runs down to the River Main is characterised by a series of approximately north - south oriented drumlins.
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). Intrusive dykes, sills and volcanic plugs occur throughout these formations. All rocks are between 50 and 60 million years old.
| Tertiary Upper Basalt Formation |
| Tertiary Interbasaltic Formation & Tardree Rhyolite |
| Tertiary Lower Basalt Formation |
The geology comprises a mix of Tertiary igneous formations in bedded, faulted and unconformable contact. Tertiary Lower Basalt Formation makes up 60% of the LCA with the remainder being the other formations in varying proportions.
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). Throughout LCA115, 4 these two formations are separated by red, palaeoweathered beds and ashfalls of the Interbasaltic Formation. Within the Interbasaltic Formation, rhyolitic lava flows are well-known from Tardree within this LCA.
NE-SW oriented faults dominate the outcrops of Tertiary rocks and juxtapose all the above formations. The major NE-SW Sixmilewater Fault cuts the eastern area, juxtaposing lower and upper basalts
Dykes occur throughout the area: the most obvious are those seen cutting Lower Basalt Formation in the south of the LCA at Parkgate.
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 a complex mix of glacial, deglacial and post-glacial sediments. Late Midlandian till predominantly underlies the area, associated with the large ice mass that was centred on the Lough Neagh Basin. This ice moved approximately northwards from an ice divide running along the crestline of the Belfast Hills. However, there are significant areas of drift free bedrock that run down as ridges from the uplands of the Antrim Plateau that are separated by incised valleys. Davies and Stephens (1978) consider that the final stages of ice-wasting in the east of Northern Ireland probably involved wide scale stagnation, downwasting and withdrawal inland towards the Lough Neagh lowlands (p.176). This would have left upland areas such as the Antrim Plateau ice free and surrounded by encircling ice. Under these conditions it would appear that a number of ice marginal lakes were created in the valleys that drained the uplands. This has left a legacy of glaciolacustrine deposits that formed as deltaic deposits that infilled these lakes. In addition to the glaciolacostrine deposits, there is are glaciofluvial deposits in the west of the LCA that extend into the adjoining Ballymena Farmlands (LCA 116) and represent deposition by meltwater as Lough Neagh ice retreated from the upland areas at the end of The Midlandian. Finally, ribbons of alluvial deposits mark the floodplains of the present-day rivers.
Key Elements
AONBThe north central part of this LCA includes a very limited area of the Antrim Coast and Glens AONB (1988). This designation is indicative of the scenic quality of the landscape.