Mynydd Merthyr is a broad ridge of high ground between Taff Vale (

Welsh Welsh may refer to: Related to Wales * Welsh, referring or related to Wales * Welsh language, a Brittonic Celtic language spoken in Wales * Welsh people People * Welsh (surname) * Sometimes used as a synonym for the ancient Britons (Celtic peop ...

Cwm Taf) and the Cwm Cynon in the Valleys region of South

Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...

. It forms the boundary between the unitary authorities of

Rhondda Cynon Taff Rhondda Cynon Taf (; RCT; also spelt as Rhondda Cynon Taff) is a county borough in the south-east of Wales. It consists of five valleys: the Rhondda Fawr, Rhondda Fach, Cynon, Taff (Welsh: ''Taf'') and Ely valleys, plus a number of towns and vil ...

to the west and

Merthyr Tydfil Merthyr Tydfil (; cy, Merthyr Tudful ) is the main town in Merthyr Tydfil County Borough, Wales, administered by Merthyr Tydfil County Borough Council. It is about north of Cardiff. Often called just Merthyr, it is said to be named after Tydf ...

to the east. The high point of 493m is at Mynydd Gethin (OS grid reference SO 044025) (though the summit

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 nomenclature varies regionally: they a ...

is at the lower height of 491m) is the culmination of a long ridge which extends northwestwards from the confluence of the Afon Cynon and the

River Taff The River Taff ( cy, Afon Taf) is a river in Wales. It rises as two rivers in the Brecon Beacons; the Taf Fechan (''little Taff'') and the Taf Fawr (''great Taff'') before becoming one just north of Merthyr Tydfil. Its confluence with the R ...

Abercynon Abercynon (), is both a village and a community (and electoral ward) in the Cynon Valley within the unitary authority of Rhondda Cynon Taf, Wales. The community comprises the village and the districts of Carnetown and Grovers Field to the south, ...

. The ridge includes the subsidiary summits of Twyn Brynbychan and Twyn Sych. To the northwest lies Mynydd Aberdâr. Much of the hill has been planted with

coniferous forest Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All exta ...

. Its flanks are heavily scarred by mining. The village of

Aberfan Aberfan () is a former coal mining village in the Taff Valley south of the town of Merthyr Tydfil, Wales. On 21 October 1966, it became known for the Aberfan disaster, when a colliery spoil tip collapsed into homes and a school, killing 116 ch ...

sits at the foot of its eastern slopes, the scene of a

tragedy Tragedy (from the grc-gre, τραγῳδία, ''tragōidia'', ''tragōidia'') is a genre of drama based on human suffering and, mainly, the terrible or sorrowful events that befall a main character. Traditionally, the intention of tragedy ...

on 21 October 1966 when a coal tip above the village slipped and engulfed the village school killing 144 people of whom 116 were children.

Geology

The entire hill is composed of sandstones and mudstones dating from the

Carboniferous Period The Carboniferous ( ) is a Period (geology), geologic period and System (stratigraphy), system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago (Myr, Mya), to the beginning of the Permian Period, ...

. There are also numerous

coal seam Coal mining is the process of extracting coal from the ground. 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 extraction of iron from ...

s within the sequence, most of which have been worked. The upper part of the hill including the summit plateau is formed from the

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 Carbonifero ...

, a rock assigned to the Carboniferous Upper

Coal Measures In lithostratigraphy, the coal measures are the coal-bearing part of the Upper Carboniferous System. In the United Kingdom, the Coal Measures Group consists of the Upper Coal Measures Formation, the Middle Coal Measures Formation and the Lower Coal ...

. The flanks of the hill owe their steepness in part to the action of

glacial ice A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...

during the succession of

ice ages 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 gree ...

Access

Virtually all of the afforested areas and some adjoining areas of moorland are classed as

open country "Open Country" is a designation used for some UK access land. It was first defined under the National Parks and Access to the Countryside Act 1949 (and extended by the Countryside Act 1968), and was land over which an appropriate access agreeme ...

under the

CRoW Act The Countryside and Rights of Way Act 2000 (c. 37), known informally as the CRoW Act or "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 imp ...

giving a right of access to walkers. In addition there is a limited network of

public footpath A footpath (also pedestrian way, walking trail, nature trail) is a type of thoroughfare that is intended for use only by pedestrians and not other forms of traffic such as motorized vehicles, bicycles and horses. They can be found in a wide ...

s and other

public rights of way Right of way is the legal right, established by grant from a landowner or long usage (i.e. by prescription), to pass along a specific route through property belonging to another. A similar ''right of access'' also exists on land held by a gov ...

which give access to parts of the hill.Ordnance Survey 1:25,000 scale Explorer map series, sheet 166 ''Rhondda & Merthyr Tydfil/Merthyr Tudful''

References

{{coord, 51, 42, 18, N, 3, 22, 23, W, dim:5000_region:GB, display=title Mountains and hills of Merthyr Tydfil County Borough Mountains and hills of Rhondda Cynon Taf