Hatterrall Hill ( cy, Mynydd Y Gader) is a rounded peak in the Black Mountains which sits on the Wales-England border, partly in Monmouthshire,

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 ...

and partly in

Herefordshire Herefordshire () is a county in the West Midlands of England, governed by Herefordshire Council. It is bordered by Shropshire to the north, Worcestershire to the east, Gloucestershire to the south-east, and the Welsh counties of Monmouthsh ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

. Its summit at 531m is the high point of a peaty plateau which falls away steeply on all sides. Broad ridges run to the north, the southeast and southwest. To the north the ridge (known as

Hatterrall Ridge The Hatterrall Ridge (sometimes spelled Hatterall) is a ridge in the Black Mountains forming the border between Powys and Monmouthshire in Wales and Herefordshire in England. The ridge is about long, and is followed by the Offa's Dyke Path. On ...

) dips to a col at around 485m elevation before rising gradually over several kilometres towards Crib y Garth / Black Hill and

Hay Bluff Hay Bluff (Welsh: ''Penybegwn'') 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- ...

. The ridge to the southwest ends abruptly at the sheer cliff known as the Darren below which is a considerable

landslip Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, ...

ped area extending south to the hamlet of

Cwmyoy Cwmyoy is an extensive rural parish in Monmouthshire, Wales ( cy, Cwm Iou for the valley and parish, cy, Cwm-iou for the village). The standard Welsh name is ''Cwm Iau'' or ''Cwm-iau''. In the Gwentian dialect of Welsh that was spoken here until ...

with its mis-shapen church. The Welsh part of the hill falls within the

Brecon Beacons National Park The Brecon Beacons National Park ( cy, Parc Cenedlaethol Bannau Brycheiniog) is one of three national parks in Wales, and is centred on the Brecon Beacons range of hills in southern Wales. It includes the Black Mountain ( cy, Y Mynydd Du) i ...

Access

The upper parts of Hatterrall Hill are all designated as

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 are freely accessible to walkers. Several public footpaths and other public rights of way give access onto the open land from the

Vale of Ewyas The Vale of Ewyas ( cy, Dyffryn Ewias) is the steep-sided and secluded valley of the River Honddu, in the Black Mountains of Wales and within the Brecon Beacons National Park. As well as its outstanding beauty, it is known for the ruins of Ll ...

(

Llanthony Llanthony (, cy, Llanddewi Nant Honddu ) is a village in the community of Crucorney on the northern edge of Monmouthshire, South East Wales, United Kingdom. Location Llanthony is located in the Vale of Ewyas, a deep and long valley with ...

Valley) to the west and from the

Monnow The River Monnow ( cy, Afon Mynwy) marks the England–Wales border for much of its length. After flowing through southwest Herefordshire, England, and eastern Monmouthshire, Wales, its confluence with the River Wye is approximately south of ...

valley to the east. The

Offa's Dyke Path Offa's Dyke Path ( cy, Llwybr Clawdd Offa) is a long-distance footpath loosely following the Wales–England border. Officially opened on 10 July 1971, by Lord Hunt, it is one of Britain's National Trails and draws walkers from throughout th ...

long distance trail A long-distance trail (or long-distance footpath, track, way, greenway) is a longer recreational trail mainly through rural areas used for hiking, backpacking, cycling, horse riding or cross-country skiing. They exist on all continents exce ...

runs from north to south over the hill as does the

Beacons Way The Beacons Way (Welsh: Ffordd y Bannau) is a waymarked long distance footpath in the Brecon Beacons National Park, Wales. It is a linear route which runs for east to west through the National Park, and passes many of the most important lan ...

Geology

The hill is composed from sandstones and mudstones of the Senni Beds Formation of the

Old Red Sandstone The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also exte ...

which is of Devonian age. Numerous small quarries adorn its slopes though all are now abandoned. The

was occupied by

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

s during the

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gre ...

s though the plateau was probably ice-free.British Geological Survey 1:50,000 map sheet 214 'Talgarth' & accompanying 'sheet explanation'

References

{{Reflist Mountains and hills of Monmouthshire Hills of Herefordshire Black Mountains, Wales