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Three reservoirs sit towards the southern edge of the moor. Llangynidr
Reservoir was constructed at the head of the Ebbw Fach River whilst Carno Reservoir is about 1km downstream where the open moorland was afforested during the twentieth century. Shon-Sheffrey's Reservoir lies on the Sirhowy River
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of South Wales, situated 500m to the east of the top of Garn Fawr. The Carno Adit is a major horizontal tunnel driven beneath the mountain from the south. It intersects a cave system and has provided useful additional information about the area's geological make-up. Other caves include
254:. The B4560 road from Garnllydan to Llangynidr cuts across the high moorland to the east of the mountain and offers the easiest access to both Mynydd Llangynidr and to Mynydd Llangatwg to its east. To the west a minor road heads north from the
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at the moor's southwestern margin. Llangynidr
Reservoir is supplemented by feeder channels constructed across the moor from tributary streams of the Ebbw Fach which otherwise empty into the main river below the dam.
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to the north of it. It is essentially an undulating plateau rising in the west to a height of 557m at Garn Fawr at OS grid ref SO 123151. A secondary high point is achieved at a point marked by a
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whilst that at Blaen Onneu in the northeast has not been worked since the 1980s. There are also a few small quarries for limestone which predate the larger workings. Some small scale mining of
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field, describing the site as a part of 'the best
British example of an interstratal karst'. The SSSI extends to 896.8 hectares. The designation process was completed in February 2013.
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and which have foundered in many places as the underlying limestone has dissolved over millennia. The larger part of the mountain has a pock-marked appearance due to the hundreds of
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was also carried out near the head of Cwm
Carneilw before the middle of the nineteenth century. There are a handful of small abandoned workings for sandstone in the
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121:, also often still referred to by its earlier name, the Basal Grit. The less frequently exposed sandstone of the southern part is the lowermost Westphalian age
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occur along the northern edges and this rock underlies the entire mountain. The plateau is formed from coarse sandstones ('gritstones') also dating from the
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and its tributary the Nant Trefil define its western margins. A further tributary, the Nant
Milgatw, reaches in from the south whilst the sharp edge of
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to roam at will. There are few defined paths though two public footpaths cross from north to south from
Llangynidr towards
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on this tract of moorland, the most notable of which are Garn Fawr ('big cairn') and Carn Caws ('cheese cairn'). Other
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and Cwm
Claisfer, themselves tributary valleys of the Usk. The shallow upper valley (Cwm Carneilw) of the
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in its surface arising from the presence of the limestone beneath the sandstone cover. The frequently
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A couple of major limestone quarries intrude upon the mountain. There is an active quarry at
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141:(or sometimes 'Chartists Cave'), so named as it was reputed to be a hiding place for the
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British
Geological Survey 1:50,000 map sheet 232 'Abergavenny' & accompanying memoir
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Industrial Estate also defines a part of its southern margin. Passing east across the
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150:('warm cave') whose small entrance lies in an elongated shakehole at SN 140154 and
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facsimile
Ordnance Survey 1" scale mapping from 1830s Cassini Publishing Ltd (2006)
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Site of
Special Scientific Interest Citation, Countryside Council for Wales, 2012
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Ordnance Survey Explorer map OL13 'Brecon Beacons National Park: eastern area'
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and continues north as a bridleway, also offering easy access to the hill.
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outcrop on the hill's eastern margin in the vicinity of the Beaufort Road.
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The mountain is mapped as open country and therefore freely available for
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reaches into the plateau in the southeast whilst the upper reaches of the
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sandstones of the central and northern parts of the hill are the
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34:. Its southern slopes extend into the northernmost parts of the
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The most celebrated cave on Mynydd Llangynidr is Ogof Fawr or
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at SO 147159. To the north the hill overlooks the valleys of
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and limestones which dip gently southwards into the
415:Sites of Special Scientific Interest in Brecknock
275:images of Mynydd Llangynidr from Geograph website
234:cairns and a stone row together with evidence of
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177:. The SSSI citation makes reference to the
162:The area was proposed for designation as a
154:not far from Chartist Cave at SN 129151.
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342:Cassini Historical Map Old Series 161
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400:Mountains and hills of Blaenau Gwent
164:site of special scientific interest
86:Mynydd Llangynidr is formed from a
261:Road through the small village of
42:. It is named from the village of
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238:occur towards its northern edge.
170:in August 2012 in respect of its
46:which sits in the valley of the
78:which has a similar character.
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168:Countryside Council for Wales
16:Hill (557.6m) in Powys, Wales
395:Mountains and hills of Powys
323:Cambrian Cave Registry entry
312:Cambrian Cave Registry entry
193:Blaen Onneu limestone quarry
125:which forms the base of the
24:Brecon Beacons National Park
226:There are numerous ancient
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26:largely in the county of
158:Conservation designation
101:basin. Broken cliffs of
103:Carboniferous Limestone
74:, the hill merges with
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99:South Wales Coalfield
22:is a mountain in the
259:Heads of the Valleys
107:Carboniferous Period
367: /
344:The Black Mountains
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20:Mynydd Llangynidr
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371:51.817°N 3.317°W
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213:Water catchment
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92:Palaeozoic Era
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232:prehistoric
222:Archaeology
148:Ogof Cynnes
389:Categories
281:References
111:shakeholes
95:sandstones
88:layer cake
60:Ebbw River
52:trig point
44:Llangynidr
203:ironstone
185:Quarrying
143:Chartists
48:River Usk
252:Tredegar
30:, south
359:51°49′N
248:walkers
172:karstic
166:by the
82:Geology
362:3°19′W
263:Trefil
242:Access
228:cairns
199:Trefil
179:doline
68:Rassau
133:Caves
72:B4560
32:Wales
28:Powys
256:A465
90:of
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