Mynydd Llangatwg
Encyclopedia
Mynydd Llangatwg or Llangattock Mountain is a hill in the Brecon Beacons National Park in the county of Powys
, south Wales
. It is named from the village of Llangatwg
(or 'Llangattock
') which sits in the valley of the River Usk
to the north of it. It is essentially an undulating plateau rising in the west to a height of 530m at OS grid ref SO 171157 and in the east to a height of 529m at Hen Dy-aderyn / Twr Pen-cyrn. This spot is marked by a trig point
. The hill forms an impressive northern scarp overlooking the Usk valley and commonly referred to as the Llangattock Escarpment. Its southern margins are more subdued. Its eastern end is defined by the drops into the Clydach Gorge
. Beyond the B4560 to the west the hill merges with Mynydd Llangynidr
which has a similar character.
Particular features of note include 'The Lonely Shepherd', an isolated limestone pinnacle which stands at the eastern tip of the plateau, left there by quarryworkers who removed great quantities of the surrounding rock. A number of cairns are scattered across the hill, notably the sizeable pair which decorate the summit of Twr Pen-cyrn and which are thought to be of Neolithic
age. A more recent addition to the landscape was Cairn-Mound Reservoir which once impounded the headwaters of Nant yr Hafod on the southern slopes though Welsh Water
abandoned this some years ago and its bed has revegetated, though the embankment remains. A couple of gas piepelines have been laid across the mountain and their courses can be traced variously by fences, vegetation changes and marker poles.
basin. Imposing cliffs of Carboniferous Limestone
occur along the northern escarpment and this rock underlies the entire hill and hosts the extensive cave systems which lie beneath it, notably those of Ogof y Daren Cilau
and Ogof Agen Allwedd
. These two systems are amongst the longest in Britain. The plateau is formed from coarse sandstones ('gritstones') also dating from the Carboniferous period and which have foundered in many places as the underlying limestone has dissolved over millennia. The larger part of the hill has a pock-marked appearance due to the hundreds of shakeholes in its surface arising from the presence of the limestone beneath the sandstone cover.
and south to Brynmawr
and the ironworks at Nant-y-glo by two tramroads which contoured the eastern end of the hill. The upper tramway which dates from the start of the nineteenth century, runs south from Pant y Gilwern and Daren Disgwylfa and then west around the head of Cwm Clydach
. It is now a grassy footpath providing easy walking through othewise rough terrain. The lower tramway was constructed in 1828-30 and has since been converted to a public road. Both tramroads had several branches to serve individual quarries along the escarpment.
cuts across the high moorland and offers the easiest access to the hill and to Mynydd Llangynidr to its west. The hill is mapped as open country and therefore freely available for walkers to roam at will. There are few defined paths though a public footpath crosses from north to south passing just east of the top known as Twr Pen-cyrn. The former tramways mentioned above also provide easy level access around the margins of the hill.
Powys
Powys is a local-government county and preserved county in Wales.-Geography:Powys covers the historic counties of Montgomeryshire and Radnorshire, most of Brecknockshire , and a small part of Denbighshire — an area of 5,179 km², making it the largest county in Wales by land area.It is...
, south Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
. It is named from the village of Llangatwg
Llangattock (Crickhowell)
Llangattock is a village in the Brecon Beacons National Park in the south of Powys in south Wales. It lies in the Usk Valley just across the river from the town of Crickhowell...
(or 'Llangattock
Llangattock (Crickhowell)
Llangattock is a village in the Brecon Beacons National Park in the south of Powys in south Wales. It lies in the Usk Valley just across the river from the town of Crickhowell...
') which sits in the valley of the River Usk
River Usk
The River Usk rises on the northern slopes of the Black Mountain of mid-Wales, in the easternmost part of the Brecon Beacons National Park. Initially it flows north into Usk Reservoir, then east by Sennybridge to Brecon before turning southeast to flow by Talybont-on-Usk, Crickhowell and...
to the north of it. It is essentially an undulating plateau rising in the west to a height of 530m at OS grid ref SO 171157 and in the east to a height of 529m at Hen Dy-aderyn / Twr Pen-cyrn. This spot is marked by a trig point
Trig point
A triangulation station, also known as a triangulation pillar, trigonometrical station, trigonometrical point, trig station, trig beacon or trig point, and sometimes informally as a trig, is a fixed surveying station, used in geodetic surveying and other surveying projects in its vicinity...
. The hill forms an impressive northern scarp overlooking the Usk valley and commonly referred to as the Llangattock Escarpment. Its southern margins are more subdued. Its eastern end is defined by the drops into the Clydach Gorge
Clydach Gorge
The Clydach Gorge is a steep-sided valley in south-east Wales down which the River Clydach flows to the River Usk. It runs for 5.6km from the vicinity of Brynmawr in Blaenau Gwent eastwards and northeastwards to Gilwern in Monmouthshire...
. Beyond the B4560 to the west the hill merges with Mynydd Llangynidr
Mynydd Llangynidr
Mynydd Llangynidr is a hill in the Brecon Beacons National Park largely in the county of Powys, south Wales. Its southern slopes extend into the northernmost parts of the county borough of Caerphilly. It is named from the village of Llangynidr which sits in the valley of the River Usk to the north...
which has a similar character.
Particular features of note include 'The Lonely Shepherd', an isolated limestone pinnacle which stands at the eastern tip of the plateau, left there by quarryworkers who removed great quantities of the surrounding rock. A number of cairns are scattered across the hill, notably the sizeable pair which decorate the summit of Twr Pen-cyrn and which are thought to be of Neolithic
Neolithic
The Neolithic Age, Era, or Period, or New Stone Age, was a period in the development of human technology, beginning about 9500 BC in some parts of the Middle East, and later in other parts of the world. It is traditionally considered as the last part of the Stone Age...
age. A more recent addition to the landscape was Cairn-Mound Reservoir which once impounded the headwaters of Nant yr Hafod on the southern slopes though Welsh Water
Welsh Water
Dŵr Cymru Welsh Water is a company which supplies drinking water and wastewater services to most of Wales and parts of western England.It is regulated under the Water Industry Act 1991.-History:...
abandoned this some years ago and its bed has revegetated, though the embankment remains. A couple of gas piepelines have been laid across the mountain and their courses can be traced variously by fences, vegetation changes and marker poles.
Geology
Mynydd Llangatwg is formed from a layer cake of Palaeozoic era sandstones and limestones which dip gently southwards into the South Wales CoalfieldSouth Wales Coalfield
The South Wales Coalfield is a large region of south Wales that is rich with coal deposits, especially the South Wales Valleys.-The coalfield area:...
basin. Imposing cliffs of Carboniferous Limestone
Carboniferous limestone
Carboniferous Limestone is a term used to describe a variety of different types of limestone occurring widely across Great Britain and Ireland which were deposited during the Dinantian epoch of the Carboniferous period. They were formed between 363 and 325 million years ago...
occur along the northern escarpment and this rock underlies the entire hill and hosts the extensive cave systems which lie beneath it, notably those of Ogof y Daren Cilau
Ogof y Daren Cilau
Ogof y Daren Cilau is one of several cave systems in the Llangattock escarpment near Crickhowell in south Powys, Wales.Its awkward 517m entrance crawl is a natural barrier to any casual visitor and precludes the need for a locked gate to protect it from vandals.Highlights of Daren Cilau include the...
and Ogof Agen Allwedd
Ogof Agen Allwedd
Ogof Agen Allwedd or Agen Allwed, also known as Aggy, is, at 32½ km long, one of the longest cave systems in Wales, and the longest cave system on the Llangattock escarpment, where Ogof y Daren Cilau is also found....
. These two systems are amongst the longest in Britain. The plateau is formed from coarse sandstones ('gritstones') also dating from the Carboniferous period and which have foundered in many places as the underlying limestone has dissolved over millennia. The larger part of the hill has a pock-marked appearance due to the hundreds of shakeholes in its surface arising from the presence of the limestone beneath the sandstone cover.
Quarries and tramways
The greater part of the length of the northern escarpment is scarred by limestone quarries which operated for much of the ninenteenth century. The rock was removed by means of a series of tramroads or tramways which linked north via steep inclines to a wharf on the Monmouthshire and Brecon Canal at LlangattockLlangattock (Crickhowell)
Llangattock is a village in the Brecon Beacons National Park in the south of Powys in south Wales. It lies in the Usk Valley just across the river from the town of Crickhowell...
and south to Brynmawr
Brynmawr
Brynmawr is a market town in Blaenau Gwent, south Wales. The town, sometimes cited as the highest town in Wales, is situated at 1,250 to 1,500 feet above sea level and nestled at the head of the South Wales Valleys...
and the ironworks at Nant-y-glo by two tramroads which contoured the eastern end of the hill. The upper tramway which dates from the start of the nineteenth century, runs south from Pant y Gilwern and Daren Disgwylfa and then west around the head of Cwm Clydach
Clydach Gorge
The Clydach Gorge is a steep-sided valley in south-east Wales down which the River Clydach flows to the River Usk. It runs for 5.6km from the vicinity of Brynmawr in Blaenau Gwent eastwards and northeastwards to Gilwern in Monmouthshire...
. It is now a grassy footpath providing easy walking through othewise rough terrain. The lower tramway was constructed in 1828-30 and has since been converted to a public road. Both tramroads had several branches to serve individual quarries along the escarpment.
Access
The B4560 road from Garnllydan to LlangynidrLlangynidr
Llangynidr is a village in Powys, Wales, about west of Crickhowell and south-east of Brecon. The River Usk flows through the village as does the Monmouthshire and Brecon Canal on which there are four locks....
cuts across the high moorland and offers the easiest access to the hill and to Mynydd Llangynidr to its west. The hill is mapped as open country and therefore freely available for walkers to roam at will. There are few defined paths though a public footpath crosses from north to south passing just east of the top known as Twr Pen-cyrn. The former tramways mentioned above also provide easy level access around the margins of the hill.