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39-455: In the northern part of the moors are the areas known as Minera Mountain and Esclusham Mountain . Further south are Ruabon Mountain and Eglwyseg Mountain . In the west the moors reach their greatest height at Cyrn-y-Brain , 565 metres (1,854 ft) above sea level. To the north and north-east, the moors are bounded by Minera Limeworks and the Clywedog valley. In the east they slope down to

78-465: A distinct South Wales-Mendip province which extends from Pembrokeshire in the west through southern Carmarthenshire , Glamorgan and south Powys to Monmouthshire , Gloucestershire and north Somerset . These rocks continue eastwards at depth beneath Oxfordshire . The Carboniferous Limestone sequence of South Wales and the Bristol area is currently (2012) subdivided thus: The limestone found north of

117-460: A greater distance across the limestone as underground channels and chambers fill up. Large sinkholes are called 'swallowholes' or 'potholes'. Gaping Gill , Alum Pot and the Buttertubs are well-known examples. Dry valleys are valleys without streams. Watlowes Valley is an excellent example. It was formed originally by a subglacial meltwater stream which existed during the last major Ice Age . After

156-590: A rich variety of wildlife including black grouse , red grouse , short-eared owl and ring ouzel . A single-track road runs across the northern part of the mountain from Minera , through Pool Park and Gwter Siani, to Eglwyseg and on towards Llangollen . Several footpaths, popular with ramblers, also run across the mountain, including the Offa's Dyke Path . 53°00′31″N 03°08′49″W  /  53.00861°N 3.14694°W  / 53.00861; -3.14694 Carboniferous Limestone Carboniferous Limestone

195-756: Is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian Epoch of the Carboniferous Period . These rocks formed between 363 and 325 million years ago. Within England and Wales, the entire limestone succession, which includes subordinate mudstones and some thin sandstones, is known as the Carboniferous Limestone Supergroup . Within Great Britain

234-422: Is a hard sedimentary rock made largely of calcium carbonate. It is generally light-grey in colour. It was formed in warm, shallow tropical seas teeming with life. The rock is made up of the shells and hard parts of millions of sea creatures, some up to 30 cm in length, encased in carbonate mud. Fossil corals, brachiopods and crinoids are frequently in evidence as components of Carboniferous Limestone; indeed

273-428: Is an area of almost bare, flat rock and is arguably the most fascinating feature of any area of Carboniferous limestone. They develop after the rock has been exposed by the scouring action of an ice sheet or glacier . Existing joints are subsequently exploited by the action of chemical weathering carbonation to form deep grykes and rounded blocks called clints . Grykes have a habitat of their own, which encourages

312-513: Is completely dry, and a great attraction to rock climbers. A gorge is a steep-sided valley , often formed in a limestone area as the result of the collapse of a roof above a cave system. Gordale Scar is an excellent example. Caves are common subsurface features in limestone landscapes. In the Yorkshire Dales , there are numerous caves, three of which – Ingleborough Cave , White Scar Caves and Stump Cross Caverns – are now show caves for

351-589: Is named for the limestone which characterises the heart of the Peak District and through which deep gorges have been cut by rivers such as the Wye, Dove and Manifold . The limestone is concealed beneath younger rocks to the east and west and to the north through the South Pennines . To the north the limestone is exposed once again in east Lancashire and in the Yorkshire Dales . There are numerous limestone hills in

390-459: Is part of the Ruabon Moors . It rises to a height of 460 m (1509 feet), with the nearby spur of Cyrn-y-Brain , to the west, reaching 473 m (1550 feet). It lies mostly within the community of Esclusham . A smaller spur to the north, known as Minera Mountain, is within the neighbouring community of Minera . The underlying rocks are a Carboniferous Limestone along with some Millstone Grit to

429-568: The Arnside and Silverdale AONB and in the southern Lake District e.g. Whitbarrow Scar with coastal exposures around the northern margins of Morecambe Bay such as Humphrey Head . An outcrop extends from Kirkby Stephen along the western side of the Vale of Eden and wraps around the northern margin of the Lake District as far as Cleator Moor . North again, it is a major landscape forming feature in

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468-525: The Black Mountain to Cribarth above the upper Swansea Valley . It is here referred to as the ‘north crop’ as distinct from a sub-parallel outcrop, the ‘south crop’ which defines the southern rim of the South Wales Coalfield . The outcrop continues through Ystradfellte to Pontneddfechan , Penderyn and Pontsticill . It then runs near the southern margin of the national park via Trefil and

507-662: The Great Orme at Llandudno , the neighbouring Little Orme and a zone of country in inland Denbighshire running through Denbigh and Ruthin . A broader belt forms high ground immediately east of the Clwydian Hills extending south to form the impressive west-facing Eglwyseg escarpment north of Llangollen and continuing as a broken outcrop southwards beyond Oswestry . There are a few outcrops in Shropshire such as Titterstone Clee Hill and at Little Wenlock . The White Peak

546-454: The Llangattock escarpment to Blorenge where it turns southwards. A very narrow ‘east crop’ and ‘south crop’ run by Cwmbran and north of Cardiff. It turns west again to meet Swansea Bay at Porthcawl . West of the bay, the rock forms the renowned southern coast of Gower between Mumbles Head and Worms Head . There are further occurrences in the Vale of Glamorgan , both inland and on

585-1137: The North Pennines and thence through Northumberland to the Northumberland Coast where it extends to the Scottish border at Berwick-upon-Tweed . There are scattered outcrops along the north coast of the Solway Firth . Limestones occur in southern Ayrshire and in a very broken band running northeastwards through the Pentland Hills towards Edinburgh . There are limited outcrops on the coasts of East Lothian and Berwickshire , isolated outcrops in Fife and Stirlingshire and further occurrences around Greenock and Dumbarton . Carboniferous Limestone occurs most famously around The Burren in County Clare , western Ireland where it produces one of western Europe's most important karst landscapes. Carboniferous Limestone

624-584: The Offa's Dyke Path crosses the region. It is rife with controversy after two satellite tagged hen harriers mysteriously disappeared here in 2018 and a raven was found poisoned in 2019. 53°01′59″N 3°08′13″W  /  53.033°N 3.137°W  / 53.033; -3.137 Esclusham Mountain Esclusham Mountain ( Welsh : Mynydd Esclus or Mynydd Esclys ) is an area in Wrexham County Borough , Wales , United Kingdom , and

663-514: The Fron-dêg Flat, has typical moorland vegetation of heather , bilberry and sedge ; rarer plants include the dark red helleborine . Hill farming is still practised, with sheep grazing across the moor. There are still surface remains of former lead workings, particularly in the areas known as Pool Park and Gwter Siani, with the foundations of old engine-houses, managers' residences and chimneys being visible in some places. The moorland supports

702-628: The Wales-London-Brabant Massif and south of the emergent Southern Uplands block is identified as a separate northern province. It is characterised by the presence of numerous ‘blocks’ and ‘basins’ each with its own particular depositional style. To the north of the Southern Uplands are the limestones of the Scottish Midland Valley stretching from Ayrshire and Arran in the west to Fife , Lothian and Berwickshire in

741-519: The Yorkshire Dales and Brecon Beacons. Typically from 1–20 m deep and 1–60 m across, they form as a result of the subsurface collapse of limestone or through the more gradual dropping of surface material into caves. Streams flowing from higher impermeable slopes sink into the ground when they reach permeable limestone. During dry spells all water sinks very quickly on reaching the limestone, through sinkholes . In wetter conditions water flows

780-399: The ceiling as the water continues to drip. When the water drips on to the floor of the cavern some evaporation occurs here also leaving a trace of limestone. Again over thousands of years a stalagmite is formed. A stone pillar is formed when a stalagmite and stalactite meet. Because it is brittle, the use of Carboniferous Limestone for building stone tends to be limited to those areas where it

819-666: The coast. An important outlier is that of the Forest of Dean basin which forms the cliffs of the Wye Valley , straddling the England/Wales border and extends southwestwards through Chepstow to Undy . The larger part of the Mendip Hills are formed from Carboniferous Limestone, showing notable geomorphological features, including Cheddar Gorge , Burrington Combe and the show cave of Wookey Hole . The Avon Gorge west of Bristol and

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858-683: The coastal cliffs at Clevedon and Weston-super-Mare are cut in this rock. The limestone islands of Flat Holm and Steep Holm are prominent in views across the mouth of the Severn Estuary . There are limited outcrops on the Isle of Man and more extensive ones in Anglesey notably along the Menai Strait , around Benllech and towards Puffin Island . The Carboniferous Limestone belt extends eastwards to form

897-478: The east. The area was rich in minerals, particularly lead and zinc deposits. The South Minera Vein, a fault fissure rilled with mineral matter, ran through the area of Esclusham Mountain and, until the second decade of the 20th century, there were many lead mines in the area, some of whose levels joined with the substantial system of natural caves beneath the mountain. The 8 km long Minera Caves, Ogof Llyn Parc and Ogof Cefn-y-Gist have their entrances on

936-616: The east. Though of Carboniferous age, the limestones of this Scottish province are not assigned to the Carboniferous Limestone Supergroup. The Carboniferous Limestone is widespread throughout Ireland. The Carboniferous Limestone is a significant landscape-forming rock unit in each of the depositional provinces of Great Britain within which it is found. Within Pembrokeshire the Carboniferous Limestone forms

975-421: The fact that the rocks are now above sea-level and no longer horizontal. The 'classic limestone walk' is a circular 10 km route from the field centre on the north side of Malham Tarn to the village of Malham, UK via Watlowes Valley and back again via Gordale Scar . Surface depressions, typically funnel-shaped and variously known as shakeholes, sinkholes , solution hollows and dolines are very common in

1014-467: The growth of shade-loving ferns such as hart's tongue and dog's mercury . During the last Ice Age, a stream is thought to have poured over Malham Cove - the most spectacular feature in the Yorkshire Dales. At the end of the Ice Age the limestone, which had been frozen solid, once again became permeable, allowing the water to disappear through its joints. Now Malham Cove is a high cliff (83 m high) – it

1053-424: The ice retreated, the valley was further developed by a meltwater stream flowing across the limestone while it was frozen solid. Watlowes Valley is a particularly good example of a dry valley because it has a textbook profile - the south-facing side is less steep than the north-facing side. This results from the weathering and mass movement processes that have operated in the post-glacial period. A limestone pavement

1092-422: The limestone is pervious. As this happens the limestone is dissolved and removed in solution. Caverns are often found below the surface in the limestone and as the lime-rich water finds its way underground it begins to drip from the roof of the cavern. It is cold underground so there is little evaporation but some does take place leaving a trace of limestone on the roof. Over thousands of years a stalactite forms from

1131-518: The moor. These have passages close to Ogof Dydd Byraf and Ogof Llyn Du whose entrances are in Minera Limeworks . These are Sites of Special Scientific Interest , and are being targeted for development as a possible tourist and educational resource. The area shows signs of use by Neolithic and Bronze Age farmers, and evidence of early inhabitants of the area exists in the form of several stone cairns and other features. The high ground

1170-470: The nineteenth, with the application of techniques brought from Cornwall . The mines were further developed in the nineteenth century under the guidance of the mining engineer and entrepreneur John Taylor : at their peak they were the most productive lead mines in Britain. The lower eastern slopes of the mountain have a landscape of pastureland, small farms and woods. The higher moorland above Fron-dêg, known as

1209-569: The north-western side. Ruabon Moors are part of the Clwydian Range and Dee Valley Area of Outstanding Natural Beauty and a Site of Special Scientific Interest , hosting a wide variety of plant and animal life. Large parts of the moors are covered with heather . Where there are outcrops of limestone on the surface a number of scarce plants can be found such as prickly sedge , dark red helleborine and rigid buckler-fern . The moors are managed for red grouse shooting. Huge numbers were shot in

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1248-460: The original forest. Mining has taken place in the area since Roman times and there are still many shafts of disused lead , zinc , silver and coal mines dotting the area. During the Second World War bombs were dropped on the moors by German planes heading to and from Liverpool and a number of bomb craters can still be seen today. The area is popular with walkers and rock-climbers and

1287-462: The past (an average of 4658 per year from 1900 to 1913) but numbers have now decreased dramatically. The area is also home to black grouse and a major conservation programme has caused their population to increase in recent years. Other birds which can be seen include peregrine falcon , merlin , hen harrier , short-eared owl and ring ouzel . The area has been modified by human activity since prehistoric times when people built cairns and cleared

1326-402: The public. In Ireland there is a large number of show caves open to visitors - Crag Cave , Ailwee Cave and Marble Arch Caves . The stalagmite and stalactite are the two main subsurface features in a Carboniferous Limestone area. These are formed when rainwater - a weak carbonic acid capable of dissolving limestone - percolates through it via the grykes and joints underground. This means

1365-641: The rock is full of fossils. Carboniferous Limestone has horizontal layers (beds) with bedding planes, and vertical joints. These joints are weaknesses in the rock, which are exploited by agents of both denudation and weathering . They also lead to an important characteristic of Carboniferous Limestone – its permeability . Water seeps through the joints in the limestone. This creates a landscape geologists call karst , which lacks surface drainage but which has all manner of characteristic surface and subsurface features. The Carboniferous Limestone has been folded and faulted by massive Earth movements which can be seen by

1404-595: The spectacular coastal cliffs at St Govan's Head along from which are features such as Huntsman's Leap and the Green Bridge of Wales , a natural arch. It forms prominent headlands such as those of Stackpole Head and Lydstep Point and the cliffs at Tenby . A narrow, intensely quarried outcrop runs inland from Carmarthen Bay through Carmarthenshire from Kidwelly , entering the Brecon Beacons National Park at Llandyfan and extending westwards through

1443-621: The suite of rocks known traditionally as the Carboniferous Limestone Series was deposited as marine sediments in three distinct ‘provinces’ separated by contemporary landmasses. One of these landmasses was the Wales-London-Brabant Massif , an east–west aligned belt of land stretching through central Wales and the English Midlands to East Anglia and on into Belgium . The limestones deposited to its south form

1482-561: The villages of Rhosllannerchrugog and Ruabon . There are several small reservoirs in this area. At the southern edge of the moors the cliffs of Eglwyseg Rocks overlook the River Dee and the Vale of Llangollen . On the western side there are more cliffs at World's End while the Horseshoe Pass separates the moors from Llantysilio Mountain . Llandegla Forest , a large conifer plantation, covers

1521-424: Was good summer pasture , and in the mediaeval period there are references to hafodydd (summer houses for those overseeing the grazing flocks) in the possession of Valle Crucis Abbey on the northern part of Esclusham Mountain. Though there may have been small-scale mining of lead on the mountain in earlier periods, development of the area's mineral resources started in earnest from the eighteenth century and into

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