Craig Cerrig-gleisiad is a subsidiary summit of
Fan Fawr
is a mountain in the Fforest Fawr section of the Brecon Beacons National Park, in Powys, Wales
Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the n ...
in the
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 ...
section of the
Brecon Beacons
The Brecon Beacons (; ) are a mountain range in Wales. The range includes South Wales's highest mountain, Pen y Fan (), its twin summit Corn Du (), and Craig Gwaun Taf (), which are the three highest peaks in the range. The Brecon Beacons ha ...
National Park
A national park is a nature park designated for conservation (ethic), conservation purposes because of unparalleled national natural, historic, or cultural significance. It is an area of natural, semi-natural, or developed land that is protecte ...
,
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 ( ...
. It makes up half of the
with its sister peak
Fan Frynych.
The summit is marked by a pile of stones, and sits on the edge of steep north facing cliffs which provide one of the few habitats for
Arctic–alpine plants this far south in the
British Isles
The British Isles are an archipelago in the Atlantic Ocean, North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner Hebrides, Inner and Outer Hebr ...
. To the south-west is
Fan Llia
Fan Llia is a subsidiary summit of Fan Fawr in the Fforest Fawr section of the Brecon Beacons National Park, Wales. In common with other peaks in the Fforest Fawr uplands it lies within the county of Powys.
The hill has the form of a broad ridg ...
.
Geology
The outstanding feature of the mountain is the L-shaped glacial
cwm which faces to the northeast. Its modern form is considered to be the result of a complex history of both
glacial
A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
action and rock-slope failure, a portion of the west wall having collapsed after the main part of the last ice age. Some of the debris was re-worked during the
Loch Lomond Stadial
The Younger Dryas (YD, Greenland Stadial GS-1) was a period in Earth's geologic history that occurred circa 12,900 to 11,700 years Before Present (BP). It is primarily known for the sudden or "abrupt" cooling in the Northern Hemisphere, when the ...
and parts stretch as far as the A470 road.
[Richard Shakesby, Classic Landforms of the Brecon Beacons, 2002, Geological Association Landform Guides series no 13] The rocks exposed in the main crag are Senni Beds of
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 ...
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 ...
, topped with
Brownstones.
The ledges of the main crag to the south have been a favoured nesting site for
peregrine falcons
The peregrine falcon (''Falco peregrinus''), also known simply as the peregrine, is a cosmopolitan bird of prey (raptor) in the family Falconidae renowned for its speed. A large, crow-sized falcon, it has a blue-grey back, barred white underpa ...
.
References
External links
www.geograph.co.uk : photos of Fan Fawr and surrounding area
Fforest Fawr
Mountains and hills of Powys
Hewitts of Wales
Nuttalls
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