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 of the Brecon Beacons National Park and Fforest Fawr Geopark. 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'. [1]
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 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. [2]
![Y Pigwm, Trecastle, Breconshire. Plan of the Roman Marching Camps at Y Pigwm [The Beacon], drawn by William Rees in 1854 Y Pigwm.jpeg](http://upload.wikimedia.org/wikipedia/commons/thumb/5/57/Y_Pigwm.jpeg/300px-Y_Pigwm.jpeg)
There are several round barrows and a stone circle on Mynydd Bach Trecastell dating to Bronze Age Britain. The Roman roads from CICVCIVM (Y Gaer) to MORIDVNVM (Moridunum, Carmarthen) via Llandovery ran over the hill and evidence of a couple of castras and a Roman fortlet remains on the hill.
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 direction.
Waun Fach is, with a summit height of 811 metres (2,661 ft), the highest mountain in the Black Mountains in south-eastern Wales. It is one of the three Marilyns over 600 m that make up the range, the others being Black Mountain and Mynydd Troed. To the north Rhos Fawr and the Radnor Forest can be seen. It is the third highest mountain in Britain south of Snowdonia. It is situated at the head of the Grwyne Fechan valley, above and to the west of the Grwyne Fawr reservoir. It has an undistinguished rounded summit. The nearby tops on the ridge, Pen Trumau and Pen y Gadair Fawr, although lower, are very much more recognisable.
Fan Fawr is a mountain in the Fforest Fawr section of the Brecon Beacons National Park, in Powys, Wales and over 734 m (2,408 ft) high.
Fforest Fawr is an extensive upland area in the county of Powys, Wales. Formerly known as the Great Forest of Brecknock in English, it was a royal hunting area for several centuries but is now used primarily for sheep grazing, forestry, water catchment and recreation. It lies within the Brecon Beacons National Park.
Fan Bwlch Chwyth is a peak in the Fforest Fawr section of the Brecon Beacons National Park and within the county of Powys.
Cefn Llechid is a small area of unenclosed land in the Brecon Beacons National Park east of Sennybridge in the county of Powys, Wales. It lies within Fforest Fawr Geopark. Its plateau-like summit surface peaks at 400m where it is marked by a trig point. A couple of small bodies of water lie in a hollow on the plateau. The hill is owned and managed by the Brecon Beacons National Park Authority.
Mynydd Illtud is an extensive area of common land near Libanus, Powys, Wales, located in the Brecon Beacons National Park and some three miles south-west of Brecon. The common is an undulating plateau lying between 330 and 370 metres above sea level. Its highest points are 381 metres (1,250 ft) at Allt Lom and 367 metres (1,204 ft) at Twyn y Gaer trig point overlooking the valley of the River Usk. Twyn y Gaer is the site of an Iron Age hill fort.
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 tributary the Grwyne Fechan flow into the River Usk at Glangrwyney.
Allt yr Esgair is a hill in the Brecon Beacons National Park in Powys, Wales. It is commonly referred to locally as simply 'The Allt'. The Welsh name signifies 'wooded slope of the ridge'. It takes the form of a northwest-southeast aligned ridge which rises to a height of 393m and which overlooks the valley of the River Usk to the west and south. To the northeast are panoramic views across Llangorse Lake to the Black Mountains There is a viewfinder on the summit erected as a monument to Eirene Lloyd White, Baroness White of Rhymney. It is a Marilyn with a prominence of 199 metres.
Y Garn Goch is a hill in the Brecon Beacons National Park in the east of Carmarthenshire, Wales. The name means the 'red cairn'. It lies near the village of Bethlehem, three miles southwest of Llangadog and four miles east of Llandeilo on the southern side of the broad Towy Valley. It is also commonly known as either Garn Goch or Carn Goch. Current owners and land managers are the Brecon Beacons National Park Authority.
Cefn Cul is a hill in the Fforest Fawr sector of the Brecon Beacons National Park in Powys, southern Wales. It is a broad north-northeast to south-southwest aligned ridge whose summit reaches a height of 562 m above sea level. The hill is bounded to the west by the upper valley of the River Tawe though which the old Trecastle road runs whilst to the east is the pass of Bwlch Bryn-rhudd over which the A4067 road runs from the Crai valley south to that of the Tawe.
Mynydd-y-glog is a hill just east of the village of Penderyn in the northern corner of the county borough of Rhondda Cynon Taff in south Wales. It lies within the Brecon Beacons National Park and Fforest Fawr Geopark. Its summit plateau rises to a height of 389m / 1277 ft at OS grid ref SN 982088, a spot marked by a trig point. To its north lies the partly dry valley of Pant Sychbant which forms the eastern extension of Cwm Cadlan. Its southern slopes are drained by various streams which feed into the Afon Cynon.
Trichrug is a hill four miles east of Llandeilo and 3 miles south of Llangadog in the county of Carmarthenshire, southwest Wales. It lies within the Brecon Beacons National Park and Fforest Fawr Geopark. Its summit at a height of 415m above sea level is marked by a trig point. It is a Marilyn with a prominence of 191 metres.
Mynydd Myddfai is a hill 4.5 miles southeast of Llandovery in the county of Carmarthenshire, southwest Wales. It lies within the Brecon Beacons National Park and Fforest Fawr Geopark. The hill is in the form of a broad ridge aligned southwest to northeast with three or four distinct tops separated by cols. The northwest side drops steeply away towards the village of Myddfai whilst the other side is a more shallow slope down towards Glasfynydd Forest which encircles Usk Reservoir. The plateau surface of the hill rises to a height of 440m at OS grid ref SN 806297 where a trig point has been erected.
Mynydd Troed is a hill in the Black Mountains of the Brecon Beacons National Park in Powys, south Wales. Its name literally translates to "Foot Mountain," based how it appears when viewed from the Allt Mawr ridge.
Mynydd Llangorse is a hill on the western edge of the Black Mountains in the Brecon Beacons National Park in Powys, south Wales. It lies two miles east of Llangors and its lake and 5 miles south of Talgarth. Its summit at 515m overtops the location 600m to the south at which a trig point is sited by 9m. The broad spur of Cefn Moel extends south towards the village of Bwlch whilst a spur to the southeast forms Pen Tir which reaches just over 450m above sea level. It is a Marilyn with a prominence of 161 metres.
Crug Mawr is a hill in the Black Mountains in the Brecon Beacons National Park in southern Powys, Wales. Its summit at a height of 550 m (1,805 ft) is marked by a trig point. The peak sits high above the valleys of the Grwyne Fawr 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.
Pen-y-crug is a hill in the Brecon Beacons National Park in the county of Powys, south Wales. It is commonly referred to locally as simply 'The Crug'. The Welsh name signifies 'top of the mound'. It slopes are moderately gently on three sides; only to the west do they steepen somewhat. Its flat trig point adorned summit at 331m overlooks the valley of the River Usk to the south. To the southeast are panoramic views over Brecon whilst eastwards are the Black Mountains and south the Brecon Beacons.
This article describes the geology of the Brecon Beacons National Park in mid/south Wales. The area gained national park status in 1957 with the designated area of 1,344 km2 (519 sq mi) including mountain massifs to both the east and west of the Brecon Beacons proper. The geology of the national park consists of a thick succession of sedimentary rocks laid down from the late Ordovician through the Silurian and Devonian to the late Carboniferous period. The rock sequence most closely associated with the park is the Old Red Sandstone from which most of its mountains are formed. The older parts of the succession, in the northwest, were folded and faulted during the Caledonian orogeny. Further faulting and folding, particularly in the south of the park is associated with the Variscan orogeny.
Mynydd Garnclochdy is a gentle summit on the long moorland ridge which extends south from Blorenge towards Pontypool and which defines the boundary between the modern county of Monmouthshire to the east and the county borough of Torfaen to the west though historically it was entirely within the traditional county of Monmouthshire. Its summit, at a height of 448 m (1407 ft), is marked by a small cairn. The summit and the eastern slopes of the hill fall within the Brecon Beacons National Park. A southern top of the hill, Mynydd Garn-wen achieves a height of 436m, and carries a trig point further south again at an elevation of 425m. To the north the broad moorland ridge runs via a poorly defined 425m top and a col at 404m elevation just south of a minor east–west road, into Mynydd y Garn-fawr, east of Blaenavon.
| International | |
|---|---|
| National | |
