Trichrug (also referred to as Pen-y-bicws) 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. [1] It is a Marilyn with a prominence of 191 metres.
The hill is formed from a suite of rocks of mid-Silurian age which are tilted steeply towards the southeast forming a part of the Myddfai Steep Belt. The summit and the crest of the ridge extending southwest and northeast is formed from the Trichrug Sandstone. Its northwestern slopes are largely formed in the mudstones and sandstones of the Hafod Fawr Formation whilst its southeastern slopes are largely formed from the Raglan Mudstone Formation. These rocks are the uppermost (i.e. youngest) Silurian rocks of the area but are also considered to be the lowermost (i.e. oldest) beds of the Old Red Sandstone succession. [2]
There is no public access to the summit though a public footpath contours the hill at half-height on its northwestern side and an unmetalled public road passes through the col known as Bwlch y Gors immediately to its west. The Beacons Way descends this track northwards towards Y Garn Goch en route for Llangadog.
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.
Sugar Loaf, sometimes called The Sugar Loaf, is a hill situated 2 miles (3.2 km) north-west of Abergavenny in Monmouthshire, Wales and sits within the Brecon Beacons National Park. It is the southernmost of the summit peaks of the Black Mountains, with a height of 1,955 feet (596 metres). Sugar Loaf was gifted to the National Trust by suffragette Lady Rhondda.
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.
Fan Llia is a subsidiary summit of Fan Fawr in the Fforest Fawr section of the Brecon Beacons National Park, Wales. In common with other peaks in the Fforest Fawr uplands it lies within the county of Powys.
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.
Fan Fraith is a top of Fan Gyhirych in the Fforest Fawr section of the Brecon Beacons National Park in the county of Powys, south Wales. Its summit is at a height of 2192 feet or 668 m. It lies within Fforest Fawr Geopark.
Picws Du is the second highest peak of the Carmarthen Fans in the Carmarthenshire section of the Black Mountain in the west of the Brecon Beacons National Park in south Wales. The highest peak is Fan Foel immediately next along the ridge and it is a subsidiary summit of Fan Brycheiniog. Picws Du falls within Fforest Fawr Geopark and its prominent summit is marked by a large Bronze Age round barrow at a height of 2457 feet above sea level. Waun Lefrith is the other, lower summit of the Bannau Sir Gâr / Carmarthen Fans situated to the west. The peak overlooks the glacial lake of Llyn y Fan Fach in the cwm below. As the peak sits on the edge of the escarpment on a ridge which juts out into the valley below, the views from the summit are panoramic and extensive. The views to the north are especially impressive when the weather is clear, looking towards the Cambrian Mountains, Mynydd Epynt and Brecon. Swansea and the Bristol Channel can just be seen on the horizon to the south, across the gently falling dip slope. Pen y Fan and Corn Du are distinctive landmarks seen directly to the east across Fforest Fawr.
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.
Foel Fraith is a hill in the Black Mountain in the county of Carmarthenshire, southwest Wales. It lies within the Brecon Beacons National Park and Fforest Fawr Geopark. Its plateau-like summit attains a height of 602 metres (1,975 ft) above sea level. To the north the subsidiary summit of Cefn y Cylchau reaches 556 feet (169 m), and to the southeast is the subsidiary summit of Carn Fadog or Cefn Carn Fadog, which reaches a height of 512 metres (1,680 ft).
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 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'.
Gaer is the name of a hill in the Black Mountains of the Brecon Beacons National Park in Monmouthshire, south Wales. It lies at the southern end of the long ridge between the valley of the Grwyne Fawr and the Vale of Ewyas one mile to the north of Bryn Arw and 3 miles northeast of Sugarloaf. Its summit at 427m above sea level sits within an Iron Age hillfort known as Twyn y Gaer.
The geology of Monmouthshire in southeast Wales largely consists of a thick series of sedimentary rocks of different types originating in the Silurian, Devonian, Carboniferous, Triassic and Jurassic periods.
Hay Bluff is a prominent hill at the northern tip of the Black Mountains, an extensive upland massif which straddles the border between south-east Wales and England. The mountain sits at the point where the main northeast-facing escarpment of the Black Mountains meets the northwest facing escarpment, the next peak to the west being Twmpa. The flat summit of Hay Bluff which is marked by a triangulation pillar at a height of 677 metres (2,221 ft) overlooks the middle Wye Valley and the book town of Hay-on-Wye.
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.
Buckland Hill is a low hill in the Brecon Beacons National Park in the county of Powys in Wales. Sitting transversely across the Usk valley between the river and the village of Bwlch, it provides excellent panoramic views down the valley and across to the Black Mountains. The summit at 316m above sea level is marked by an OS trig point though this is now within a dense conifer plantation and so no longer affords any outward views. Buckland Hall sits at the foot of the hill's afforested northwestern side.
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.