Corn Du is a summit of the twin topped

Pen y Fan Pen y Fan () is the highest peak in South Wales, situated in Brecon Beacons National Park (Bannau Brycheiniog). At above sea-level, it is also the highest British peak south of Cadair Idris in Snowdonia. It is the highest point (List of countie ...

and the second highest peak in

South Wales South Wales ( ) is a Regions of Wales, loosely defined region of Wales bordered by England to the east and mid Wales to the north. Generally considered to include the Historic counties of Wales, historic counties of Glamorgan and Monmouthshire ( ...

at 871.5 m (2,864 ft), situated in the

Brecon Beacons National Park Brecon Beacons National Park, officially named Bannau Brycheiniog National Park (), is a National parks of the United Kingdom, national park in Wales. It is named after the Brecon Beacons (), the mountain range at its centre. The national park ...

. It is situated to the south-west of Pen y Fan at a distance of approximately 550 m from it, and is just 13 m (43 ft) lower than Pen y Fan itself. The summit is marked by a well structured

Bronze Age The Bronze Age () was a historical period characterised principally by the use of bronze tools and the development of complex urban societies, as well as the adoption of writing in some areas. The Bronze Age is the middle principal period of ...

cairn A cairn is a human-made pile (or stack) of stones raised for a purpose, usually as a marker or as a burial mound. The word ''cairn'' comes from the (plural ). Cairns have been and are used for a broad variety of purposes. In prehistory, t ...

with a central burial

cist In archeology, a cist (; also kist ; ultimately from ; cognate to ) or cist grave is a small stone-built coffin-like box or ossuary used to hold the bodies of the dead. In some ways, it is similar to the deeper shaft tomb. Examples occur ac ...

like that on nearby Pen y Fan. The two summits are visible from great distances owing to their height above the surrounding

moorland Moorland or moor is a type of Habitat (ecology), habitat found in upland (geology), upland areas in temperate grasslands, savannas, and shrublands and the biomes of montane grasslands and shrublands, characterised by low-growing vegetation on So ...

, and are famous

landmark A landmark is a recognizable natural or artificial feature used for navigation, a feature that stands out from its near environment and is often visible from long distances. In modern-day use, the term can also be applied to smaller structures ...

s. The views from the peaks are also panoramic and very extensive, the Black Mountain and

Fforest Fawr Fforest Fawr (, ) is an extensive upland area in the county of Powys, Wales. Formerly known as the Great Forest of Brecknock in English, it was a royal hunting area for several centuries but is now used primarily for sheep grazing, forestry, wate ...

being especially obvious to the west. Mynydd Epynt is visible to the north behind the county town of

Brecon Brecon (; ; ), archaically known as Brecknock, is a market town in Powys, mid Wales. In 1841, it had a population of 5,701. The population in 2001 was 7,901, increasing to 8,250 at the 2011 census. Historically it was the county town of Breck ...

, and other parts of the escarpment to the east.

Access

The summit is often crossed on the way to Pen y Fan, and forms part of a well-known circuit of the Beacons. It offers good views down into Cwm Llwch and across the Usk valley to

as well as east towards the Sugar Loaf, Monmouthshire above

Abergavenny Abergavenny (; , , archaically , ) is a market town and Community (Wales), community in Monmouthshire, Wales. Abergavenny is promoted as a "Gateway to Wales"; it is approximately from the England–Wales border, border with England and is loca ...

.Nuttall, John & Anne (1999). The Mountains of England & Wales - Volume 1: Wales (2nd edition ed.). Milnthorpe, Cumbria: Cicerone. . Tommy Jones' Obelisk is found on its western flanks, in between the summit and Y Gyrn. All of the surrounding

is open to access, but crossing some parts of the terrain such as

peat bog A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muske ...

s is more difficult and the main paths are well-engineered and maintained by the

National Trust The National Trust () is a heritage and nature conservation charity and membership organisation in England, Wales and Northern Ireland. The Trust was founded in 1895 by Octavia Hill, Sir Robert Hunter and Hardwicke Rawnsley to "promote the ...

Geology

The summit is very similar to that of Pen y Fan: flat and anvil-shaped. It is similarly formed from the relatively erosion-resistant

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

age sandstones from the Upper

Old Red Sandstone Old Red Sandstone, abbreviated ORS, 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 eastern seaboard of North America. It ...

known as the Plateau Beds. The

rock strata In geology and related fields, a stratum (: strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ...

are clearly visible at the edge of the escarpment, where they form a resistant edge to the cliff. The same strata are visible all along the escarpment facing north, as well as the rearward edge facing south-east and lying behind the main peaks. The same Plateau Beds recur in the Black Mountain (range) to the west, and cap the summits of Picws Du and Fan Foel, as well as forming steep cliffs below the peaks. Tommy Jones Obelisk - geograph

Glacial lakes

Corn Du approached from the South - geograph

Nearby is one of the few natural lakes in the park, the small Llyn Cwm Llwch. It may be compared with the much larger

glacial lake A glacial lake is a body of water with origins from glacier activity. They are formed when a glacier erodes the land and then melts, filling the depression created by the glacier. Formation Near the end of the last glacial period, roughly 10,0 ...

s of Llyn y Fan Fach and Llyn y Fan Fawr below the main ridge of the Black Mountain about 15 miles west of the central Brecon Beacons

escarpment An escarpment is a steep slope or long cliff that forms as a result of faulting or erosion and separates two relatively level areas having different elevations. Due to the similarity, the term '' scarp'' may mistakenly be incorrectly used inte ...

. All three are of glacial origin and were formed during the last

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 g ...

by ice scouring out hollows below the peaks, the water being partly dammed by

moraine A moraine is any accumulation of unconsolidated debris (regolith and Rock (geology), rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a gla ...

s of rock debris carried down by ice action subsequent to plucking and frost shattering.

References

External links

Photos of Pen y Fan and surrounding area
{{coord, 51.88328, N, 3.43684, W, region:GB_source:enwiki-osgb36(SO012215), display=title Brecon Beacons Mountains and hills of Powys Tourist attractions in Powys Landmarks in Wales Hewitts of Wales Nuttalls Glyn Tarell