The River Honddu () (pronounced ''hon-thee'') is a

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

in the Black Mountains 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 ...

, southeast

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 ...

. Early recorded versions of the name are of the form ''Hothenei'' and ''hodni'' which are believed to contain the adjective 'hawdd' meaning for example, pleasant or easy. Later forms such as ''Honddye'' have undergone metathesis whereby -ddn- became -ndd-. The river is over 24km in length. It rises within the county of

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 ...

near the

Gospel Pass The Gospel Pass (Welsh language, Welsh: ''Bwlch yr Efengyl'') is the highest road pass in Wales. It is at the head of the Vale of Ewyas in the Black Mountains, Wales, Black Mountains of southeast Wales. Starting from Hay-on-Wye the narrow moun ...

at the head of the

Vale of Ewyas The Vale of Ewyas () is the steep-sided and secluded valley of the River Honddu, in the Black Mountains of Wales and within the Brecon Beacons National Park. As well as its outstanding beauty, it is known for the ruins of Llanthony Priory, ...

down which it flows, passing southwards into

Monmouthshire Monmouthshire ( ; ) is a Principal areas of Wales, county in the South East Wales, south east of Wales. It borders Powys to the north; the English counties of Herefordshire and Gloucestershire to the north and east; the Severn Estuary to the s ...

Llanvihangel Crucorney Llanvihangel Crucorney () is a small village in the community (parish) of Crucorney, Monmouthshire, Wales. It is located north of Abergavenny and southwest of Hereford, England on the A465 road. Setting Llanvihangel Crucorney lies on the ea ...

before turning northeastwards to join the

River Monnow The River Monnow () marks the England–Wales border for much of its length. After flowing through southwest Herefordshire, England, and eastern Monmouthshire, Wales, its confluence with the River Wye is approximately south of Monmouth. The ...

at the point on the Wales-England border where that river too makes a sudden change of direction. The only significant

tributary A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which they ...

to join the Honddu is the Nant Bwch though numerous smaller streams flow down the steep sides of the Vale of Ewyas to add to the river's flow. It is likely that the Honddu continued on a southerly course beyond Llanvihangel Crucorney prior to the last ice age but has since been diverted by the presence of a large

terminal moraine A terminal moraine, also called an end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front e ...

which stretches impressively across the valley to the west of the village. The southwest to northeast alignment of both the Honddu and the Monnow appear to be related to the course of the

Neath Disturbance The Neath Disturbance is a geological structure which stretches across south Wales from Swansea Bay northeastwards as far as Hereford in western England. It consists of a series of both faults and associated folds which were active during the mo ...

, an ancient geological weakness, which runs through the valley to the north of the

Sugarloaf A sugarloaf was the usual form in which refined sugar was produced and sold until the late 19th century, when granulated and cube sugars were introduced. A tall cone with a rounded top was the end product of a process in which dark molasses, ...

and on towards

Hereford Hereford ( ) is a cathedral city and the county town of the ceremonial county of Herefordshire, England. It is on the banks of the River Wye and lies east of the border with Wales, north-west of Gloucester and south-west of Worcester. With ...

. The upper valley of the Honddu has the characteristic U-shape of a glacially scoured valley though it is not clear where the ice originated that cut this deep trench through the eastern Black Mountains. The modern Honddu is thus something of a misfit river. It has been speculated that glacial ice from the Wye valley glacier invaded the Vale of Ewyas over the Gospel Pass, though no evidence of any

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 ...

containing clasts of rock from mid Wales has yet been found within the valley to support that proposal.British Geological Survey 1:50,000 map sheet 214 'Talgarth' & accompanying sheet explanation Within the valley is

Llanthony Priory Llanthony Priory () is a partly ruined former Augustinians, Augustinian priory in the secluded Vale of Ewyas, a steep-sided once-glaciated valley within the Black Mountains, Wales, Black Mountains area of the Brecon Beacons National Park in Mo ...

, a popular attraction for the many visitors to the National Park. Towards the lower end of the Vale of Ewyas is

Cwmyoy Cwmyoy is an extensive rural parish in Monmouthshire, Wales (, for the valley and parish; , for the village). The standard Welsh name is ''Cwm Iau'' or ''Cwm-iau''. In the Gwentian dialect of Welsh that was spoken here until the late 1800s, the ...

with its celebrated church, distorted by the movement of the hillside on which it stands; the entire hamlet has been built on an ancient, and not entirely dormant,

landslide Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides ...

References

External links

{{authority control Honddu Honddu Honddu