Mynydd Llangatwg or Llangattock Mountain is a hill in the
Brecon Beacons National Park The Brecon Beacons National Park ( cy, Parc Cenedlaethol Bannau Brycheiniog) is one of three national parks in Wales, and is centred on the Brecon Beacons range of hills in southern Wales. It includes the Black Mountain ( cy, Y Mynydd Du) in ...
in the county of
Powys Powys (; ) is a county and preserved county in Wales. It is named after the Kingdom of Powys which was a Welsh successor state, petty kingdom and principality that emerged during the Middle Ages following the end of Roman rule in Britain. ...
, south
Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in 20 ...
. It is named from the village of Llangatwg (or ' Llangattock') which sits in the valley of the
River Usk The River Usk (; cy, Afon Wysg) rises on the northern slopes of the Black Mountain (''y Mynydd Du''), Wales, in the westernmost part of the Brecon Beacons National Park. Initially forming the boundary between Carmarthenshire and Powys, it fl ...
to the north of it. It is essentially an undulating plateau rising in the west to a height of at and in the east to a height of at Hen Dy-aderyn / Twr Pen-cyrn. This spot is marked by a
trig point A triangulation station, also known as a trigonometrical point, and sometimes informally as a trig, is a fixed surveying station, used in geodetic surveying and other surveying projects in its vicinity. The nomenclature varies regionally: they ...
. The shallow pool of Pwll Gwy-rhoc sits in a broad depression towards the northern edge of the plateau whilst a smaller pool frequently occupies a large shakehole a few hundred metres to its west. 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 The Clydach Gorge (also known as Cwm Clydach) is a steep-sided valley in south-east Wales down which the River Clydach flows to the River Usk. It runs for from the vicinity of Brynmawr in Blaenau Gwent eastwards and northeastwards to Gilwern in ...
. 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 The Neolithic period, or New Stone Age, is an Old World archaeological period and the final division of the Stone Age. It saw the Neolithic Revolution, a wide-ranging set of developments that appear to have arisen independently in several p ...
age. Some freshwater ponds litter the mountain, including the “witches pool”. 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 pipelines have been laid across the mountain and their courses can be traced variously by fences, vegetation changes and marker poles.


Mynydd Llangatwg is formed from a layer cake of Palaeozoic Era sandstones and limestones which dip gently southwards into the South Wales Coalfield basin. Imposing cliffs of
Carboniferous Limestone Carboniferous Limestone 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 an ...
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 The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonif ...
and which have foundered in many places as the underlying limestone has dissolved over millennia. The sandstone forming low secondary scarps above the main northern and eastern escarpments is the frequently conglomeratic Twrch Sandstone often still referred to by its earlier name, the Basal Grit. In contrast, the more poorly exposed sandstone forming the high ground of the centre of the hill is the lowermost Westphalian age Farewell Rock which marks the base of the South Wales Coal Measures. Sections of the hill have a pock-marked appearance due to the dozens 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 nineteenth 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 Llangattock 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 otherwise 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. Both the Twrch Sandstone and Farewell Rock have been quarried on a small scale in the past alongside the B4560 Beaufort Road with larger quarries in the latter once operating near the hill's southwestern corner.


The B4560 road from Garnllydan to Llangynidr cuts across the high moorland and offers the easiest access to the hill and to Mynydd Llangynidr to its west. Almost the entire hill is designated as urban common and was mapped as open country under the provisions of the Countryside and Rights of Way Act 2000 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.


External links

Images of Mynydd Llangatwg from Geograph website
{{coord, 51.8236, -3.1667, type:mountain_region:GB, display=title Mountains and hills of Powys Brecon Beacons