Gilwern Hill is a 441 m high hill 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 (range), Black Mountain ...

, south of the village of

Gilwern Gilwern is a village within the Brecon Beacons National Park in Monmouthshire, Wales. Historically in Brecknockshire, it extends to either side of the River Clydach, Monmouthshire, River Clydach on the south side of the River Usk, Usk valley. It ...

Monmouthshire Monmouthshire ( cy, Sir Fynwy) is a county in the south-east of Wales. The name derives from the historic county of the same name; the modern county covers the eastern three-fifths of the historic county. The largest town is Abergavenny, with ...

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 lies west of the

Blorenge Blorenge, also called The Blorenge (; cy, Blorens), is a prominent hill overlooking the valley of the River Usk near Abergavenny, Monmouthshire, southeast Wales. It is situated in the southeastern corner of the Brecon Beacons National Park. The ...

. The hill is a

Site of Special Scientific Interest A Site of Special Scientific Interest (SSSI) in Great Britain or an Area of Special Scientific Interest (ASSI) in the Isle of Man and Northern Ireland is a conservation designation denoting a protected area in the United Kingdom and Isle of ...

Geology

Gilwern Hill is formed from a series of rock strata of

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

age, each of which dip moderately southwards. The summit plateau is formed from

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

s - the

Farewell Rock The Farewell Rock is the name given to a series of sandstones at the boundary of the Coal Measures with the underlying Marros Group in South Wales. Once thought to be a single sandstone, it is now accepted that the same name has been applied to se ...

and the

Twrch Sandstone 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 geographi ...

which overlie the

Carboniferous Limestone Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian Epoch of the Carboniferous Period. These rocks formed between 363 and ...

. The latter has been extensively quarried around the eastern, northern and western margins of the hill where it is exposed. Derelict tramways are in evidence in connection with the working of these quarries for limestone in connection with iron and steel-smelting.British Geological Survey 1:50K map sheet 232 ''Abergavenny''

Access and recreation

Virtually the entire hill is designated 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 ...

and so access is therefore available freely to walkers. A minor road wraps around its southern and western margins whilst a couple 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 a

restricted byway A byway in the United Kingdom is a track, often rural, which is too minor to be called a road. These routes are often unsurfaced, typically having the appearance of ' green lanes'. Despite this, it is legal (but may not be physically possible) to ...

cross the northern and eastern slopes of the hill. The quarries provide a minor venue for

rock climbing Rock climbing is a sport in which participants climb up, across, or down natural rock formations. The goal is to reach the summit of a formation or the endpoint of a usually pre-defined route without falling. Rock climbing is a physically and ...

References

External links

Historic landscape of Gilwern Hill

UKC Rock Climbing info on Gilwern Hill
{Dead link, date=December 2022 , bot=InternetArchiveBot , fix-attempted=yes Sites of Special Scientific Interest in Monmouthshire Mountains and hills of Monmouthshire