The old road over y Pygwn, Trecastell - geograph

Mynydd Bach Trecastell is a hill on the border between the counties of

Carmarthenshire Carmarthenshire ( cy, Sir Gaerfyrddin; or informally ') is a county in the south-west of Wales. The three largest towns are Llanelli, Carmarthen and Ammanford. Carmarthen is the county town and administrative centre. The county is known as ...

and

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 ...

in southwest

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 ...

. It lies within the Black Mountain (range) of 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 ...

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 ...

. Its summit is plateau-like and reaches a height of 412m at OS grid ref SN 827312 at Y Pigwn. The name signifies the 'little hill of castle town'.

Geology

The summit of the hill is formed in sandstones and siltstones of the Cae'r Mynach Formation which like all of the rocks are tilted steeply to the southeast as part of a geological structure called the Myddfai Steep Belt. The flaggy micaceous sandstones of the Tilestones Formation immediately overlies these beds and this is followed in turn by the thick sequence of the Raglan Mudstone Formation. These latter two formations are assigned as the oldest parts 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 ...

though date from the Silurian. To the northwest are the various sandstones, mudstones and siltstones of the Aberedw, Hafod Fawr, Cwm Graig Ddu and Halfway Farm Formations. A series of northwest to southeast aligned faults cut through this succession and give rise to minor features in the landscape.British Geological Survey 1:50,000 map sheet 213 'Brecon' & accompanying sheet explanation

Archaeology

There are several round barrows and a stone circle on Mynydd Bach Trecastell dating to Bronze Age Britain. The

Roman roads Roman roads ( la, viae Romanae ; singular: ; meaning "Roman way") were physical infrastructure vital to the maintenance and development of the Roman state, and were built from about 300 BC through the expansion and consolidation of the Roman Re ...

from ''CICVCIVM'' (

Y Gaer Y Gaer () is a Roman fort situated near modern-day Brecon in Mid Wales, United Kingdom. Y Gaer is located at (Landranger 160). History Y Gaer was built around AD 75 and sits on a crossroads of Roman roads in the valley of the River Usk at a ...

) to ''MORIDVNVM'' ( Moridunum, Carmarthen) via

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

ran over the hill and evidence of a couple of castras and a Roman fortlet remains on the hill.

Access

Mynydd Bach Trecastell is largely designated as open country and so freely accessible to walkers. The old Roman road provides access onto the hill from the

Trecastle Trecastle ( cy, Trecastell) ("the town of the castle") is a village in Powys, Wales, situated on the edge of the Brecon Beacons National Park ( cy, Parc Cenedlaethol Bannau Brycheiniog) and in the community of Llywel. The village has a populatio ...

direction.

References

External links

Images of Mynydd Bach Trecastell and surrounding area on Geograph website
{{Coord, 51.967, -3.707, type:mountain_region:GB, display=title Mountains and hills of Carmarthenshire Mountains and hills of Powys Black Mountain (hill)