Nant Llech
Encyclopedia
The Nant Llech is a minor river in Powys
Powys
Powys is a local-government county and preserved county in Wales.-Geography:Powys covers the historic counties of Montgomeryshire and Radnorshire, most of Brecknockshire , and a small part of Denbighshire — an area of 5,179 km², making it the largest county in Wales by land area.It is...

, 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...

 and which lies wholly within the Brecon Beacons National Park. The name means 'slab stream', presumably in reference to the sandstones across which it runs. Its headwater streams, the Nant Llech Pellaf and the Nant Llech Isaf join forces at Blaen Llech and then continue westwards as the Nant Llech for 3 km / 2mi to a confluence with the River Tawe
River Tawe
The River Tawe is a river in South Wales. It flows in a principally south-westerly direction for some from its source below Moel Feity in the Old Red Sandstone hills of the western Brecon Beacons to the Bristol Channel at Swansea. Its main tributaries are the right bank Upper and Lower Clydach...

 just east of the village of Abercrave.

Waterfall

The most famous feature of the river is Henrhyd Falls
Sgwd Henrhyd
Sgwd Henrhyd in Powys, Wales, is the tallest waterfall in South Wales with a drop of . It lies on National Trust land on the southern edge of the Brecon Beacons National Park....

 (Sgwd Henrhyd or Rhaeadr Henrhyd in Welsh
Welsh language
Welsh is a member of the Brythonic branch of the Celtic languages spoken natively in Wales, by some along the Welsh border in England, and in Y Wladfa...

), a 27m / 90ft high fall where the river plunges over the edge of a band of hard sandstone known as the 'Farewell Rock
Farewell Rock
The Farewell Rock is the name given to a series of sandstones which lie 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 several different sandstones of similar age...

' into a deep plunge pool. The river continues below in a steep wooded gorge cut into mudstones and sandstones of the Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

 age 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...

. The falls are owned and managed by the National Trust
National Trust for Places of Historic Interest or Natural Beauty
The National Trust for Places of Historic Interest or Natural Beauty, usually known as the National Trust, is a conservation organisation in England, Wales and Northern Ireland...

 who provide a free car park off the minor road between Coelbren
Coelbren
Coelbren may mean:* Coelbren, Powys, a village in the south-west of the Brecon Beacons National Park in Wales.* Coelbren , a supposed "druidic" alphabet invented by Iolo Morganwg ....

 and Pen-y-cae for visitors wanting to explore the area.

A public footpath runs the length of the valley though part runs across a landslip area which has been active in recent years. The river gorge is a site of special scientific interest
Site of Special Scientific Interest
A Site of Special Scientific Interest is a conservation designation denoting a protected area in the United Kingdom. SSSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in Great Britain are based upon...

. Sir William Edmond Logan
William Edmond Logan
Sir William Edmond Logan was a Scottish-Canadian geologist.Logan was born in Montreal, Quebec, and educated at the High School in Edinburgh and the University of Edinburgh . He started teaching himself geology in 1831, when he took over the running of a copper works in Swansea. He produced a...

, first director of the Geological Survey of Canada discovered some fossil trees near the base of the falls. These are now on display outside Swansea Museum
Swansea Museum
The Swansea Museum in Swansea, Wales, UK is the oldest museum in Wales. The building was built for the Royal Institution of South Wales in 1841 in the neo-classical style.-Main museum:...

.
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