Mynydd Marchywel is a high
hill
A hill is a landform that extends above the surrounding terrain. It often has a distinct summit, and is usually applied to peaks which are above elevation compared to the relative landmass, though not as prominent as Mountain, mountains. Hills ...
in the Neath Port Talbot area in South Wales. Its summit is marked both by a cairn and a
trig point
A triangulation station, also known as a trigonometrical point, and sometimes informally as a trig, is a fixed surveying station, used in geodetic surveying and other surveying projects in its vicinity.
The station is usually set up by a map ...
. The larger part of the hill is cloaked in modern forestry through which numerous streams fall away westward to the
River Tawe
The River Tawe (; ) is a long river in South Wales. Its headwaters flow initially east from its source below Llyn y Fan Fawr south of Glasfynydd Forest, Moel Feity in the Black Mountain (range), Black Mountains, the westernmost range of the ...
, eastward to the
River Dulais
River Dulais () is a river of Wales which has its source at Mynydd y Drum. It joins the River Neath after flowing over Aberdulais Falls
The Aberdulais Falls are found on the River Dulais at Aberdulais, near Neath in the county borough of Neath ...
and southward into the
Clydach, the latter two being tributaries of the
River Neath
River Neath () is a river in south Wales running south west from the point at which its headwaters arising in the Brecon Beacons National Park converge to its mouth at Baglan Bay below Briton Ferry on the east side of Swansea Bay.
Course U ...
.
Geology
The hill is formed from multiple layers of
Pennant Sandstone
The Pennant Measures is the traditional name for a sequence of sedimentary rocks of the South Wales Coalfield. They were also referred to as the Upper Coal Measures and assigned to the Westphalian 'C' and Westphalian 'D' stages of the Carbonifer ...
with intervening
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...
layers and occasional
coal seam
Coal mining is the process of extracting coal from the ground or from a mine. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extrac ...
s. All are tilted to the south and southwest towards the axis of the
South Wales Coalfield
The South Wales Coalfield () extends across Pembrokeshire, Carmarthenshire, Swansea, Neath Port Talbot, Bridgend, Rhondda Cynon Taf, Merthyr Tydfil, Caerphilly, Blaenau Gwent and Torfaen. It is rich in coal deposits, especially in the South Wales ...
syncline
In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimposed ...
. Parts of its slopes are mantled by
glacial till
image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
. The coal seams have been worked extensively in the past. One of the last operations was that at
Gleision Colliery under the northwestern side of Mynydd Marchywel.
Scheduled monuments
;Mynydd Marchywel summit cairn: This
Round cairn
A bowl barrow is a type of burial mound or tumulus. A barrow is a mound of earth used to cover a tomb. The bowl barrow gets its name from its resemblance to an upturned bowl. Related terms include ''cairn circle'', ''cairn ring'', ''howe'', ''ker ...
dating to the
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 ...
is north of the trig pont. The heap of stones, now gradually spreading, has traces of kerbstones amongst the rubble.
;Tirlan medieval house sites: (, OS grid ref:SN762026). The earthwork remains of two medieval platform houses, apart, are beside a track on the south-east flank of Mynnydd Marchywel, near Tyrlan. Cultivation ridges are also in the vicinity.
Access
Mynydd Marchywel is crossed by
Saint Illtyd's Walk
Saint Illtyd's Walk is a waymarked long-distance footpath in South Wales. It runs from Pembrey Country Park, west of Burry Port, through rural eastern Carmarthenshire and Neath Port Talbot to end at Margam Country Park, south of Port Talbot. ...
which locally runs from
Ynysmeudwy to
Crynant
Crynant () is a village and community in the Dulais Valley in Wales. It lies 7¾ miles north-east from the town of Neath in Neath Port Talbot, situated between the mountains of Mynydd Marchywel to the west, Hirfynydd to the east and Mynydd y ...
across the northern slopes of the hill, following one of the very few
public rights of way
A right of way (also right-of-way) is a specific route that people, animals, vehicles, watercraft, or utility lines travel, or the legal status that gives them the right to do so. Rights-of-way in the physical sense include controlled-access h ...
to be found on the hill. There are however numerous forest tracks and most of its western flanks, including the summit area, are designated as
open access
Open access (OA) is a set of principles and a range of practices through which nominally copyrightable publications are delivered to readers free of access charges or other barriers. With open access strictly defined (according to the 2001 de ...
under the
Countryside and Rights of Way Act 2000
The Countryside and Rights of Way Act 2000 (c. 37), also known as the CRoW Act and "Right to Roam" Act, is a United Kingdom Act of Parliament affecting England and Wales which came into force on 30 November 2000.
Right to roam
The Act impleme ...
.
[Ordnance Survey Explorer map 165 ''Swansea'']
See also
*
List of Scheduled Monuments in Neath Port Talbot
References
{{reflist
External links
images of Mynydd Marchywel and area on Geograph website
Mountains and hills of Neath Port Talbot
Marilyns of Wales