Mynydd Myddfai is a hill 4.5 miles southeast of

Llandovery Llandovery (; ) is a market town and community (Wales), community in Carmarthenshire, Wales. It lies on the River Tywi and at the junction of the A40 road, A40 and A483 road, A483 roads, about north-east of Carmarthen, north of Swansea and w ...

in the county of

Carmarthenshire Carmarthenshire (; or informally ') is a Principal areas of Wales, county in the South West Wales, south-west of Wales. The three largest towns are Llanelli, Carmarthen and Ammanford. Carmarthen is the county town and administrative centre. ...

, southwest

Wales Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the England–Wales border, east, the Bristol Channel to the south, and the Celtic ...

. It lies within the

Brecon Beacons National Park Brecon Beacons National Park, officially named Bannau Brycheiniog National Park (), is a National parks of the United Kingdom, national park in Wales. It is named after the Brecon Beacons (), the mountain range at its centre. The national park ...

and

Fforest Fawr Geopark Fforest Fawr Geopark is a Geopark in the Brecon Beacons National Park, south Wales. It is the first designated Geopark in Wales having gained membership of both the European Geoparks Network and the UNESCO-assisted Global Network of National G ...

. The hill is in the form of a broad ridge aligned southwest to northeast with three or four distinct tops separated by

col A col is the lowest point on a mountain ridge between two peaks; a mountain pass or saddle. COL, CoL or col may also refer to: Computers * Caldera OpenLinux, a defunct Linux distribution * , an HTML element specifying a column * A collision sig ...

s. The northwest side drops steeply away towards the village of

Myddfai Myddfai () is a small village and community in Carmarthenshire, Wales. It is situated south of Llandovery in the Brecon Beacons, and has a population of 415, decreasing to 398 at the 2011 census. The village is a popular tourist destination on ...

whilst the other side is a more shallow slope down towards Glasfynydd Forest which encircles

Usk Reservoir The Usk Reservoir () is located in the upper River Usk, Usk Valley, at above sea level, in the western part of the Brecon Beacons National Park, Wales. The county boundary between Carmarthenshire and Powys runs through the reservoir which lies ...

. The plateau surface of the hill rises to a height of 440m at OS grid ref SN 806297 where 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 station is usually set up by a map ...

has been erected.

Geology

The hill is composed of a variety of different rock formations all tilted steeply to the southeast in a structure known as the Myddfai Steep Belt. The summit ridge is formed from sandstones and mudstones of the Cae'r Mynach Formation. Immediately southeast of these beds is the narrow band of the Tilestones Formation along which are a line of grassed over diggings left after these flaggy micaceous sandstones were extracted for use as roof tiles. Southeast again is the thick sequence of the Raglan Mudstone Formation. These last two formations are considered to be the lowermost of the

Old Red Sandstone Old Red Sandstone, abbreviated ORS, 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 eastern seaboard of North America. It ...

sequence though assigned like the rest of the rocks forming Mynydd Myddfai to the

Silurian period The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

. Northwest of the summit ridge are the sandstones and siltstones of the Hafod Fawr Formation and beneath them more sandstones, mudstones and siltstones of the Cwm Craig Ddu and Halfway Farm Formations. Northwest to southeast oriented faults cross the ridge in places and can be seen where they offset the line of the Tilestones workings.British Geological Survey 1:50,000 map sheets 212 'Llandovery' & 213 'Brecon' & accompanying sheet explanations

Archaeology

There are several ancient

cairn A cairn is a human-made pile (or stack) of stones raised for a purpose, usually as a marker or as a burial mound. The word ''cairn'' comes from the (plural ). Cairns have been and are used for a broad variety of purposes. In prehistory, t ...

s on the hill together with the line of old quarries mentioned above. The age of these workings is unknown though they may well have been active over an extended period. A variety of

Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of Roman civilization *Epistle to the Romans, shortened to Romans, a letter w ...

remains are located on

Mynydd Bach Trecastell Mynydd Bach Trecastell is a hill on the border between the counties of Carmarthenshire and Powys in southwest Wales. It lies within the Black Mountain (range), Black Mountain range of the Brecon Beacons National Park and Fforest Fawr Geopark. It ...

just to the northeast of Mynydd Myddfai. A number of new archaeological finds in 2007/08 were made during the excavation of a deep trench across the northern end of Mynydd Myddfai for the laying of a controversial gas pipeline from

Milford Haven Milford Haven ( ) is a town and community (Wales), community in Pembrokeshire, Wales. It is on the north side of the Milford Haven Waterway, an estuary forming a natural harbour that has been used as a port since the Middle Ages. The town was ...

to Tirley in Gloucestershire.

Access

The hill is designated as open country and so freely accessible to walkers. A

bridleway A bridle path, also bridleway, equestrian trail, horse riding path, ride, bridle road, or horse trail, is a trail or a thoroughfare that is used by people riding on horses. Trails originally created for use by horses often now serve a wider ...

runs across it from the dam of the

northwest to Cwm yr Olchfa and another runs southeast from this one to meet a minor public road at the west end of the hill.

References

External links

Images of Mynydd Myddfai and surrounding area on Geograph website
{{coord, 51.9535, -3.7387, type:mountain_region:GB, display=title Mountains and hills of Carmarthenshire Black Mountain (range)