The Afon Haffes near Glyntawe - geograph

The Afon Haffes is a river in

Powys Powys ( , ) is a Principal areas of Wales, county and Preserved counties of Wales, preserved county in Wales. It borders Gwynedd, Denbighshire, and Wrexham County Borough, Wrexham to the north; the English Ceremonial counties of England, ceremo ...

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

and is wholly contained within the

Brecon Beacons National Park Brecon Beacons National Park, officially named Bannau Brycheiniog National Park (), is a National parks of the United Kingdom, national park in Wales. It is named after the Brecon Beacons (), the mountain range at its centre. The national park ...

(). Its headwaters rise on the southern and western slopes of

Fan Hir Fan Hir is a peak at the eastern end of the Black Mountain (range), Black Mountain (''Y Mynydd Du'') in the Brecon Beacons National Park (''Parc Cenedlaethol Bannau Brycheiniog'') in southern Wales. It is a subsidiary summit of Fan Brycheiniog. ...

at the eastern edge of the Black Mountain () and the river joins 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 ...

Glyntawe Glyntawe is a hamlet and parish on the upper reaches of the River Tawe in Powys, Wales, in the community of Tawe-Uchaf. It has always been sparsely populated. Today it attracts tourists for outdoor activities in the Brecon Beacons National Par ...

after a short and steep south-eastward descent of 3 km / 2 miles. Cwm Haffes is a trench which has been incised into the

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 ...

left by the glaciers of the last

ice age 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 g ...

along the geological boundary between the

Old Red Sandstone Old Red Sandstone, abbreviated ORS, is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the eastern seaboard of North America. It ...

rocks to the north and the Carboniferous Limestone rocks to the south. At the head of the incised valley is .British Geological Survey 1:50,000 shett 231 'Merthyr Tydfil' & accompanying memoir The river forms two

distributaries A distributary, or a distributary channel is a stream channel that branches off and flows a main stream channel. It is the opposite of a ''tributary'', a stream that flows another stream or river. Distributaries are a result of river bifurca ...

as it enters the

on account of its large bedload of boulders derived from the glacial material through which it has cut.

References

External links

Photos of the River Haffes on geograph.org.uk
{{DEFAULTSORT:Haffes Black Mountain (range) Fforest Fawr Rivers of the Brecon Beacons National Park Rivers of Powys