Penmoelallt
Encyclopedia
Penmoelallt or Onllwyn is a hill in the northern part of the county borough
of Rhondda Cynon Taff
in south Wales
. It lies within the Brecon Beacons National Park and Fforest Fawr Geopark
. To its east lies the deep valley of Cwm Taf and to its north a rather shallower valley in which the Nant Cadlan originates. To the west is the hill known as Mynydd-y-glog
and to the south are slopes draining into the River Taff
and the Afon Cynon
. The hill culminates in a broken plateau with several knolls rising above the 420m contour. Its afforested nature makes it difficult to determine the precise location of its highest point but this probably lies somewhere around OS grid ref SO 003096. Older maps indicate a spot height of 1376ft above sea level at SO 000090.
basin. Lowermost, and exposed along its northern and eastern scarps, are Carboniferous Limestone
s. Above these are the coarse sandstones of the Twrch sandstone (formerly the 'Basal Grit') of the Marros Group
(former 'Millstone Grit Series') whilst the southernmost slopes are formed in the lowermost beds of the Lower South Wales Coal Measures
. A couple of northwest to southeast aligned faults runs across the hill. The limestone gives rise to karst
ic scenery including numerous shakeholes some of which occur on the gritstone area as well as the limestone. There are a number of areas of gritstone pavement though most are obscured by trees.
who have dedicated their entire freehold estate as access land for walkers.
Numerous vehicular tracks (though no vehicular access for the public) run through the forest whilst a few public rights of way cross through the forest though some are difficult of access. Much of the bridleway between Ffrwd Uchaf and Pen-twyn-isaf serves as a forest track and provides ready access from Cwm Taf as does the footpath which carries the Taff Trail
between the same locations.
County borough
County borough is a term introduced in 1889 in the United Kingdom of Great Britain and Ireland , to refer to a borough or a city independent of county council control. They were abolished by the Local Government Act 1972 in England and Wales, but continue in use for lieutenancy and shrievalty in...
of Rhondda Cynon Taff
Rhondda Cynon Taff
Rhondda Cynon Taf, or RCT, is a county borough in the South Wales Valleys of Wales. It consists of 3 valleys: the Rhondda Valley, Cynon Valley and Taff-Ely Valley...
in south Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
. It lies within the Brecon Beacons National Park and Fforest Fawr Geopark
Fforest Fawr Geopark
Fforest Fawr Geopark was the first Geopark to be designated in Wales having gained membership of both the European Geoparks Network and the UNESCO-assisted Global Network of National Geoparks in October 2005. The Geopark aims to promote and support sustainable tourism and other opportunities to...
. To its east lies the deep valley of Cwm Taf and to its north a rather shallower valley in which the Nant Cadlan originates. To the west is the hill known as Mynydd-y-glog
Mynydd-y-glog
Mynydd-y-glog is a hill just east of the village of Penderyn in the northern corner of the county borough of Rhondda Cynon Taff in south Wales. It lies within the Brecon Beacons National Park and Fforest Fawr Geopark. Its summit plateau rises to a height of 389m / 1277ft at OS grid ref SN 982088,...
and to the south are slopes draining into the River Taff
River Taff
The River Taff is a large river in Wales. It rises as two rivers in the Brecon Beacons — the Taf Fechan and the Taf Fawr — before joining to form the Taff north of Merthyr Tydfil...
and the Afon Cynon
River Cynon
The River Cynon is a river in South Wales and is one of the larger tributaries of the River Taff.It arises within Cwm Cadlan in the Brecon Beacons National Park as the Nant Cadlan and is supplemented by a number of small streams arising from springs in the Carboniferous Limestone and Twrch...
. The hill culminates in a broken plateau with several knolls rising above the 420m contour. Its afforested nature makes it difficult to determine the precise location of its highest point but this probably lies somewhere around OS grid ref SO 003096. Older maps indicate a spot height of 1376ft above sea level at SO 000090.
Geology
Penmoelallt is composed of a layer cake of rocks laid down during the Carboniferous period and subsequently tilted to the south into the South Wales CoalfieldSouth Wales Coalfield
The South Wales Coalfield is a large region of south Wales that is rich with coal deposits, especially the South Wales Valleys.-The coalfield area:...
basin. Lowermost, and exposed along its northern and eastern scarps, are Carboniferous Limestone
Carboniferous limestone
Carboniferous Limestone is a term used to describe a variety of different types of limestone occurring widely across Great Britain and Ireland which were deposited during the Dinantian epoch of the Carboniferous period. They were formed between 363 and 325 million years ago...
s. Above these are the coarse sandstones of the Twrch sandstone (formerly the 'Basal Grit') of the Marros Group
Marros Group
The Marros Group is the name given to a suite of rocks of Namurian age laid down during the Carboniferous period in South Wales. These rocks were formerly known as the Millstone Grit Series but are now distinguished from the similar but geographically separate rock sequences of the Pennines and...
(former 'Millstone Grit Series') whilst the southernmost slopes are formed in the lowermost beds of the Lower South Wales Coal Measures
Coal Measures
The Coal Measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System. It represents the remains of fluvio-deltaic sediment, and consists mainly of clastic rocks interstratified with the beds of coal...
. A couple of northwest to southeast aligned faults runs across the hill. The limestone gives rise to karst
KARST
Kilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...
ic scenery including numerous shakeholes some of which occur on the gritstone area as well as the limestone. There are a number of areas of gritstone pavement though most are obscured by trees.
Access
The hill is almost entirely clothed by a coniferous plantation managed by the Forestry CommissionForestry Commission
The Forestry Commission is a non-ministerial government department responsible for forestry in Great Britain. Its mission is to protect and expand Britain's forests and woodlands and increase their value to society and the environment....
who have dedicated their entire freehold estate as access land for walkers.
Numerous vehicular tracks (though no vehicular access for the public) run through the forest whilst a few public rights of way cross through the forest though some are difficult of access. Much of the bridleway between Ffrwd Uchaf and Pen-twyn-isaf serves as a forest track and provides ready access from Cwm Taf as does the footpath which carries the Taff Trail
Taff Trail
The Taff Trail is a popular walking and cycle path that runs for between Cardiff Bay and Brecon in Wales. It is named so because it follows the course of the River Taff...
between the same locations.