Crug Mawr is a hill in the Black Mountains 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) i ...

in southern

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. Geog ...

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 ...

. Its summit at a height of 550 m (1,805 ft) 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 a ...

. The peak sits high above the valleys of the

Grwyne Fawr The Grwyne Fawr is a river in the Brecon Beacons National Park in south Wales. A section of it forms the administrative border between Powys and Monmouthshire and also of the historic counties of Brecon and Monmouth. The river and its major tri ...

and Grwyne Fechan to the north of the more well-known Sugar Loaf. The views from here across the Black Mountains are wide-ranging and also extend eastwards across Monmouthshire. Four ridges run off to the northwest, east, southeast and southwest, the last ending in the subsidiary summit of Blaen-yr-henbant.

Access

All of the upper slopes of the hill are designated as open country. A bridleway runs up from the minor road east of

Llanbedr Llanbedr () is a village and community south of Harlech. Administratively, it lies in the Ardudwy area, formerly Meirionnydd, of the county of Gwynedd, Wales. History Ancient monuments at Llanbedr include Neolithic standing stones; the St ...

and then on northwards to Mynydd Du Forest. The

Beacons Way The Beacons Way (Welsh: Ffordd y Bannau) is a waymarked long distance footpath in the Brecon Beacons National Park, Wales. It is a linear route which runs for east to west through the National Park, and passes many of the most important lan ...

runs across the slopes of the hill between

Partrishow Partrishow, also known as Patricio, Patrishow, or by its Welsh name, Merthyr Isiw, is a small village in the county of Powys (historically Brecknockshire), close to its border with Monmouthshire. It is in the valley of the Grwyne Fawr, in the ...

and Llanbedr.

Geology

In common with other hills in the Black Mountains, Crug Mawr is formed from mudstones and sandstones of the

Old Red Sandstone The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also exte ...

laid down during the

Devonian period The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...

but there is little rock exposed at the surface other than in the beds of the streams which occupy valleys such as Cwm Milaid and Cwm Beusych.British Geological Survey 1:50,000 map sheet 214 'Talgarth' & accompanying sheet explanation

References

{{Reflist Mountains and hills of Powys Black Mountains, Wales