Cefn yr Ystrad is a

mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually highe ...

in the Brecon Beacons National Park in

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 is an outlier of the Central Beacons group. The broad northeast - southwest aligned ridge reaches an elevation of . One of the southernmost peaks in the Brecon Beacons, it rises to the east of

Pontsticill Reservoir Pontsticill Reservoir () or Taf Fechan Reservoir is a large reservoir on the Taf Fechan lying partly in the county of Powys and partly within the county borough of Merthyr Tydfil in south Wales. It lies within the Brecon Beacons National Park a ...

. The summit area is a great stretch of wild moorland, with the highest point marked by a

trig point A triangulation station, also known as a trigonometrical point, and sometimes informally as a trig, is a fixed surveying station, used in geodetic surveying and other surveying projects in its vicinity. The nomenclature varies regionally: they a ...

Geology

The hill is formed from successive layers of

Carboniferous Limestone Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian epoch (geology), Epoch of the Carboniferous period (geology), Period. T ...

and the overlying Twrch Sandstone (formerly known as the ''Basal Grit'' of the Millstone Grit). The rock strata generally dip to the south but are locally disrupted by foundering of the

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

as the underlying

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

has dissolved away. There are extensive ice-smoothed pavements of the latter and loose rock abounds. The crest and southern slopes of the hill are home to dozens of

shakehole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

s, some of which reach considerable proportions.

Archaeology

The hill is scattered with

archaeological site An archaeological site is a place (or group of physical sites) in which evidence of past activity is preserved (either prehistoric or historic or contemporary), and which has been, or may be, investigated using the discipline of archaeology a ...

s from the

Bronze Age The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second prin ...

through to the industrial period. Pre-eminent amongst these are Garn Felen and Carn-y-Bugail; the latter, which translates as ‘cairn of the shepherd’, is a 15m diameter burial cairn southeast of the summit. It stands at 3m high but has been partly disturbed. Numerous nineteenth century

boundary stone A boundary marker, border marker, boundary stone, or border stone is a robust physical marker that identifies the start of a land boundary or the change in a boundary, especially a change in direction of a boundary. There are several other t ...

s can traced across the hill bearing the engraved letters ‘D of B, TM’ on the one side and ‘GH’ on the other, marking the boundary between the estates of the Duke of Beaufort, Tretower Manor and of the Gwynne Holford’s who were established at Buckland Hall near

Bwlch Bwlch (meaning ''a pass'' in Welsh) is a small village and an electoral ward in Powys, southern Wales. The settlement is strung out along the A40 road which crosses a low col above the Usk Valley at this point on its route between Brecon and Cr ...

A number of more recent structures and tracks are associated with the now-abandoned limestone quarries of Cwar Blaen-dyffryn, Cwar y Hendre and Cwar yr Ystrad on the northern and northwestern flanks of the hill.

Access

The hill lies entirely within

open country "Open Country" is a designation used for some UK access land. It was first defined under the National Parks and Access to the Countryside Act 1949 (and extended by the Countryside Act 1968), and was land over which an appropriate access agree ...

and so access on foot is freely available. A bridleway running northeast from

Pontsticill Pontsticill is a village within the county borough of Merthyr Tydfil in South Wales. It lies within the valley of the Taf Fechan on the southern edge of the Brecon Beacons National Park. The village lies within the community of Vaynor in an are ...

skirts the northwestern edge of the hill bound for Dyffryn Crawnon and the Usk Valley.Ordnance Survey 1:25K Explorer map sheet OL12 & OL13 ''Brecon Beacons National Park: western & eastern areas''

References

External links

www.geograph.co.uk : photos of Cefn yr Ystrad and surrounding area
{{coord, 51.81443, -3.32730, type:landmark_region:GB_source:enwiki-osgb36(SO086137), display=title Brecon Beacons Mountains and hills of Powys Marilyns of Wales Hewitts of Wales Nuttalls