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Clywedog Valley
Historic Landscape
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Historic Landscape Characterisation

The Clywedog Valley: Bryn y Groes
Llanidloes Without community, Powys
(HLCA 1192)


Upland plateau and hill edge south and west of the Clywedog Reservoir with widely dispersed farms of possibly medieval or early post-medieval origin associated with irregular fieldscapes and extensive 19th-century enclosure of former and existing common land; discrete mining landscapes.

Historic background

The area largely fell within the manorial township of Ystradhynod in the 19th-century Montgomeryshire tithe parish of Llanidloes.

Key historic landscape characteristics

Upland plateau and hill edge to the south and west of the Clywedog Reservoir, generally lying between a height of 290-460 metres above sea level, dissected by a number of stream valleys including the Nant Gwestyn, Nant Pen-y-banc, Nant Croes, Nant Felen, and Afon Biga. Predominantly well-drained fine loamy or fine silty soils overlying rock, which historically has been best suited to stock rearing and woodland. The area includes a number of small, 20th-century conifer plantations and shelter belts as well as several small, residual, sinuous areas of ancient semi-natural broadleaved woodland and scrub on the lower-lying steep-sided stream valleys of the Nant Pen-y-banc and Nant Gwestyn streams.

Recorded placenames in the historic landscape area are mostly topgraphical and provide little evidence of historic land use or settlement history.

Early prehistoric settlement and land use is indicated by the chance find of a stone axe hammer of Bronze Age date found near Pen-y-banc Farm and by a hilltop burial mound at Penycerrig. The small defended, hilltop enclosure with stone ramparts overlooking the Clywedog dam at Pen-y-gaer probably represents a period of settlement and land use associated with the exploitation of upland grazing during the later prehistoric Iron Age.

A mixture of fieldscape types are represented in the area and notably include irregular patterns of smaller fields encircling the lower-lying farms in stream valleys, such as Pen-y-rhynau, Foel Pen-y-banc, Deildre-fawr, Deildre-fach, and Gwestyn, which in origin appear to represent former seasonally-occupied habitations or encroachments within areas of more extensive open grazing during the medieval and early post-medieval periods. Extensive areas of the higher ground throughout the character area were the subject of parliamentary enclosure during the earlier 19th century, represented by both large and small straight-sided fields, with the exception of substantial areas of Mynydd y Groes and Bryn Mawr in the western part of the area, which though partitioned into large straight-sided fields remain as registered Common Land.

Metal mining remains mostly of mid to later 19th-century date survive in a number of areas, notably a probable drainage adit in the valley of the Nant Felen at Nant-y-Gwrdu, below the Nantmelin mine, several shafts in the Gwestyn valley associated with the Aberdaunant mine, and the more extensive remains at Gwestyn, above the valley of the Nant Gwestyn, all of which exploited mineral veins shared by the Bryntail, Penyclun and Van mines to the north-east, from which copper and lead were extracted. The mining remains at Gwestyn survive over an area of 3 hectares on the broad upland ridge at Gwestyn now forming semi-improved pasture land, which largely date from the period between the 1850s and 1870s. Visible remains include a run of shafts, trials and collapsed workings along the vein, spoil heaps, a whim circle and possible capstan circle, a stone-lined drainage adit lower down the hill near the Nant Gwestyn, and by the foundations of former mine buildings including a former engine house, explosives magazine and mine office but little ore processing appears to have been undertaken at the site. Power for drainage was also provided by a waterwheel driven by water from the Gwestyn, the use of water power being indicated by a number of earthwork reservoirs and leats.


Historic Environment Record; Cadw Listed Building descriptions; modern Ordnance Survey 1:10,000, 1:25,000 mapping and 1st edn Ordnance Survey 1:2,500 mapping; Burnham 1975; Hamer 1873; Jones 1983; Jones, Walters and Frost 2004; Moore-Colyer 2002; Spurgeon 1972; RCAHM 1911; Richards 1969; Soil Survey of England and Wales; Thomas 1955-56; Walters 1994; Williams 1990; Williams 1997

For further information please contact the Clwyd-Powys Archaeological Trust at this address, or link to the Countryside Council for Wales' web site at

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