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 Central Uplands of Tyrone and Fermanagh. This area is defined in the north by the fault-guided scarp that forms the southern edge of the Sperrin Mountains. Below this are plateau lands that decrease in height and complexity to the south, before rising again to the lower slopes of Slieve Beagh. Below ca 350m the landscape is dominated by thick drift deposits, including prominent drumlin fields, dead ice features and glaciofluvial deposits - often capped by blanket peats. Some hills rise above the general level of the plateau, most notably the basalt-capped outlier of Slieve Gallion. The southwestwards trending Clogher Valley effectively divides the southern section of the upland into two blocks, one lying between Tempo and Pomeroy and the other centred on Slieve Beagh.
Brougher Mountain is an upland area of broad sandstone ridges that extends from Cloghtogle Mountain (near Enniskillen) to Slievedivena in Omagh District. The land form of the ridges is complex. Brougher Mountain (316m) is the highest point, with deeply undulating slopes and rounded summits. Topped Mountain and Knockmany are also prominent. To the south, the ridge becomes broken and subdivided to form a crumpled plateau with numerous loughs and rounded summits. To the north, the ridge is lower, with a well-defined escarpment to the SE and a dip-slope to the NW. The upland is dissected by two straight, deep valleys, which follow this same alignment, relating closely to fault-lines. The escarpment has steep plummeting slopes and long views out over the Clogher Valley to the south and east. The lower slopes have a more convoluted landform, with broken ridges of glacial moraine in valleys and at the foot of slopes. The escarpment slopes and summits are particularly prominent and therefore sensitive to change. The landscape can therefore be summarised as one of broad, rounded sandstone ridges dissected by short, steep glens; escarpment to the north; steep summits and rounded loughs to the south. Key elements in the landscape include elements of the Tempo Valley Glaciolacustrine Complex along the southeastern border of the LCA and part of the Fintona Hills Complex.
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 - dolerite dykes - about 60 million years old |
| Carboniferous - about 350 million years old |
| Ballinimallard |
| Ballyreagh |
| Maydown |
| Topped Mountain |
| Clogher Valley |
| Ballyness |
| Devonian - Gortinfinbar, Raveagh, Shanmullagh - about 400 million years old |
| Silurian - Lisbellaw - about 420 million years old |
This LCA is dominated by fossiliferous Carboniferous rocks of the Kesh - Omagh succession. These Carboniferous strata overlie Devonian, exposed in small outcrops. The Fermanagh Carboniferous occurs in a small area to the south. Tertiary dolerite dykes extend through the area. Overall, the geology can be summarised as two areas, separated by the Tempo - Sixmilecross Fault: the southeastern and the northwestern.
Devonian conglomerates with minor sandstones and volcanic beds pass upwards into red sandstones, mudstones and siltstones with subordinate andesitic lavas typical of the Old Red Sandstone facies. Occurs in three small outcrops on the northern edge of LCA16.
The Carboniferous limestones, shales and sandstones Ballyness and Clogher formations are both exposed (ESCR Site 199) Cole Bridge Stream
Ballyreagh Conglomerate Formation: a discontinuous conglomerate with sandstones above and below occurs with the Topped Mountain Formation sandstones (ESCR Site 225) of Largy Quarry.
All the above successions were deformed in the Variscan (end Carboniferous) phase of tectonics. The NE-SW Tempo-Sixmilecross Fault crosses the centre of LCA16.
ESCR Site 226 (Glen and Coolcran - Carboniferous conglomerates) are within this LCA.
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 more than 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. 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.
As an upland area, this LCA contains large areas that are drift free and would have been overridden and scoured by Late Midlandian ice that moved southwestwards across the area from an ice centre in the Omagh basin. On the flanks of Brougher Mountain this ice left an encircling mantle of till. However, the Quaternary features that are of particuar geomorphological and geological significance are located within areas of deglacial sand and gravel that were deposited on the margins of the upland as the ice wasted. Within this LCA there are elements of a number of such deglacial complexes that are important scientifically and for their sand and gravel resources.
TheTempo Valley Delta Complex runs along the southeastern margin that overlaps with LCA17. The valley margins are defined by the bedrock uplands of the Fintona Hills to the west, and by the limit of sand and gravel to the east and covers an area of c. 30 km2. It records a range of ice marginal and ice contact sediments including glaciolacustrine outwash spreads, deltas and moraines. Deep meltwater channels through the axis of the Tempo Valley probably reflect meltwater and/or glacial lake drainage to the southwest. These deposits are superimposed upon bedrock in the uplands, and subglacial diamict of rogen moraine morphology in the lowlands. These rogen bedforms relate to earlier northeast-southwest ice flow from ice centres north of the Fintona Hills. Ice retreated east and southeast from the main axis of the Fintona Hills. Aesthetically, the Tempo Valley delta complex is excellent. As a whole the complex remains intact.
The Fintona Hills Complex, (16km2 in this LCA) is defined as the area occupied by sand and gravel sediments to the north side of the Fintona Hills, and extends from Ballinamallard to Brackagh. It is characterised by east-west aligned sand and gravel ridges, interpreted as subglacial eskers and ice-marginal moraines, kame terraces, and small outwash spreads. The Ballinamallard esker chain (mainly in LCA 15) is well-preserved with little or no sand and gravel despoilation. The esker is a discrete landscape feature, especially near Kilskeery. Moraines composed of sand and gravel around Crockfadda are large and dominant in the landscape. They contrast with the adjacent bedrock uplands around Thornoge. Undulating kame terraces at Dungoran form a distinctive topography. Sand and gravel ridge alignment and morphology contrasts with that of the surrounding diamict bedforms (rogen moraines). Esker ridges are associated with bedrock-floored meltwater channels.
In the north east of the LCA are small areas of the Clogher Valley Sub-Glacial and Ice-Marginal Complex (2.6km2) that lies mainly in LCA 17, and the Ballygawley Delta Comlex (1.5km2) that lies mainly in LCA 44.
Key Elements Deglacial ComplexesTEMPO VALLEY DELTA COMPLEX (5.8 km2)
The Tempo Valley delta complex is classified as being of high importance on a Northern Ireland scale. This is due to its importance in showing that ice retreated to the east and southeast. This is very different to the direction of ice advance. The localised occurrence of concretions and mud curls appears to be unique to this area, and have not been extensively reported in similar settings elsewhere in Northern Ireland. The pattern of deglaciation is rather different to that originally envisaged by Charlesworth. Ice retreat was far more dynamic, and involved two interacting ice margins after ice broke up over the axis of the Fintona Hills.
FINTONA HILLS glaciofluvial COMPLEX
This landform assemblage is very varied, but is generally of high importance on a Northern Ireland scale in terms of understanding the complexity of deglacial processes in Northern Ireland. The Fintona Hills Complex shows a variety of ice marginal and subglacial landforms dating from the period of ice thinning when the main ice mass split up over the axis of the Fintona Hills. This resulted in the separation of Omagh Basin and Clogher/Tempo valley ice masses to the north and south respectively. Ice mass decay was then topographically controlled. Omagh Basin ice actively retreated from the uplands and deposited a range of marginal sediments. This evidence is in agreement with adjacent regional deglaciation patterns.
CLOGHER VALLEY SUBGLACIAL AND ICE-MARGINAL COMPLEX
The Clogher Valley complex records ice marginal and subglacial sedimentation of glaciofluvial and diamict facies during glaciation and southwesterly ice retreat into the lowlands of the central Clogher Valley and the Lough Erne Basin from the surrounding uplands. For a fuller description see LCA17.
BALLYMACKILROY delta and outwash (Ballygawley DELTA complex)
The area around Ballymackilroy in the northeast of the LCA overlaps with LCAs 17, 44 and 45 and is of importance in understanding the recent glacial history of Northern Ireland. It consists of a well-defined assemblage of sand and gravel delta and outwash surfaces deposited in a pro-glacial lake. Landforms around Ballymackilroy record sand and gravel deposition following the break up of ice over the Fintona Hills and subsequent ice withdrawal towards the south, into the Clogher valley.Sand and gravel landforms around Ballymackilroy are generally pristine and this intactness is an important landscape attribute. The outwash spreads are a major component of the landscape as seen from the main -Omagh road. For a fuller description of the Ballygawley Complex see LCA 44.
DUNGORAN KAME-ESKER-OUTWASH (FINTONA HILLS glaciofluvial COMPLEX)
Undulating ridges against the northern slopes of the Fintona Hills to the south of Fintona are kame terraces resulting from sediment collapse following the removal of ice support. More sharply defined ridges along the lower slopes are eskers, which fed meltwater to the ice front during westward retreat of the Omagh Basin ice body.
DROMORE GLACIOFLUVIAL ASSEMBLAGE (FINTONA HILLS glaciofluvial COMPLEX)
Landforms along the flanks of the Glennamuck/Blackwater River valley are of importance in understanding the recent glacial history of Northern Ireland. The landform assemblage along the eastern flank of the valley consists of moraine and esker ridges and well-defined outwash terraces formed as the ice front oscillated on the slopes of the Fintona Hills, with consequent short-lived ponding. Flat outwash surfaces superimposed on the bedrock valley slopes are a distinctive component of the local landscape.
Other sites/units identified in the Earth Science Conservation Review199 Cole Bridge Stream
Carboniferous. Exposure of stratotype for both Ballyness and Clogher Vally Formations. Miospores and sparse fossils.
225 Largy Quarry
Carboniferous. Exposure of upper section of Topped Mountain Sandstone Formation. Lithologies of Ballyreagh Conglomerate Formation.
226 Glen and Coolcran
Carboniferous. Interbedded sandstones and conglomerates of Coolcran Conglomerate Member. Unusual stratotype section contains thin mudstone with miospores.