Llyn Cwm Llwch () is a small lake or pool in 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 ...

Powys Powys (; ) is a county and preserved county in Wales. It is named after the Kingdom of Powys which was a Welsh successor state, petty kingdom and principality that emerged during the Middle Ages following the end of Roman rule in Britain. Geog ...

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 between 1 and 2 acres: much smaller than the two glacial lakes in the west of the

Black Mountain (range) The Black Mountain ( cy, Y Mynydd Du) is a mountain range in South, Mid and West Wales, straddling the county boundary between Carmarthenshire and Powys (formerly Brecknockshire) and forming the westernmost range of the Brecon Beacons National ...

: Llyn y Fan Fawr and

Llyn y Fan Fach Llyn y Fan Fach ( Welsh meaning "little lake (near) the peak") is a lake of approximately on the northern margin of the Black Mountain in Carmarthenshire, South Wales and lying within the Brecon Beacons National Park. The lake lies at an altitu ...

, and one of the few natural bodies of water in the park. It is of

glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betwe ...

origin, occupying a rock hollow beneath the peaks of Pen y Fan and

Corn Du Corn Du is a summit of the twin topped Pen y Fan and the second highest peak in South Wales at 873 m (2,864 ft), situated in the Brecon Beacons National Park. The summit itself is marked by a well structured Bronze Age cairn with a cen ...

in the central

Brecon Beacons The Brecon Beacons ( cy, Bannau Brycheiniog, ) are a mountain range in South Wales. In a narrow sense, the name refers to the range of Old Red Sandstone peaks which lie to the south of Brecon. Sometimes referred to as "the central Beacons" ...

. It is drained by the Nant Cwm Llwch which empties into the

Afon Tarell The Afon Tarell is a river in Powys, Wales, which rises to the west of the Brecon Beacons in Brecon Beacons National Park and flows north, then north-east, for into the River Usk. The river is followed for its entire length through Glyn Tarell ( ...

, which itself enters the

River Usk The River Usk (; cy, Afon Wysg) rises on the northern slopes of the Black Mountain (''y Mynydd Du''), Wales, in the westernmost part of the Brecon Beacons National Park. Initially forming the boundary between Carmarthenshire and Powys, it ...

Brecon Brecon (; cy, Aberhonddu; ), 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 c ...

. Tommy Jones' obelisk, a memorial in granite to a young boy who died near this spot in 1900, overlooks the lake.

Geology

The lake occupies a hollow excavated in the sandstones of the Brownstones 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 ...

by glacial action during the succession of recent ice ages. Its northern margins are rimmed by a large curved late-glacial

moraine A moraine is any accumulation of unconsolidated debris ( regolith and 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 glacier or ice sh ...

.British Geological Survey 1:50,000 map sheet 231 'Brecon' & accompanying sheet explanation

Access

The lake is within open country and readily accessible to walkers. A popular path up to Pen y Fan runs southwards up Cwm Llwch, passing by the outlet of the lake. The lake is seen to advantage from the peaks of both Pen y Fan and

and indeed from the spur of Pen Milan to its west. Llyn Cwm Llwch, a small lake in the Brecon Beacons, Wales

References

External links

images of Llyn Cwm Llwch and surrounding area on Geograph website
{{authority control Glyn Tarell Brecon Beacons Cwm Llwch Cwm Llwch