Afon Ystwyth, from Source to Cardigan Bay

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SN7974 : Cwm Ystwyth by Andrew Longton
The Afon Ystwyth is a river located entirely in Ceredigion. It is 39km long from its source in the upland bogs of the Elenydd (about 390m above mean sea level) east of Cwmystwyth to its mouth at Aberystwyth on the Cardigan Bay.




Open on a MapExternal link | View as list with descriptionsExternal link.

Towns and villages along the Ystwyth

SN7873 : View of Cwmystwyth from Esgair Milwyn by Rudi WinterSN7372 : Main road, Pontrhydygroes by Nigel BrownSN6275 : Llanilar by John LucasSN5877 : Field and housing, Llanfarian by Nigel CallaghanSN5879 : Rhydyfelin viewed from Tanybwlch beach by John Lucas
CwmystwythPont-Rhyd-y-GroesLlanilarLlanfarianRhydyfelin
8km14km28km34km36kmfrom the source
200m140m30m10m10mabove MSL

The upland section of the Ystwyth is very remote country, and the first settlement of any size is Cwmystwyth (200m above MSL) at 8km from the source, followed by Pont-rhyd-y-groes (140m) at 14km. Llanilar (30m) is reached after 28km. Llanfarian at 34km and Rhydyfelin at 36km are on the southern outskirts of Aberystwyth, and the river is approaching its tidal limit at about 37km. The town of Aberystwyth itself isn't actually directly on the river.

Geology

1:50,000 Modern Day Landranger(TM) Map © Crown Copyright
1:50,000 Modern Day Landranger(TM) Map © Crown Copyright

Map: Site of the capture of the Teifi by the Ystwyth. The north-south section of the river at Pont-Rhyd-y-Groes follows the original river bed of the then Teifi. The abandoned valley runs southward to the west of Ysbyty Ystwyth.
The rock formations along the entire length of the Ystwyth, along with most of the Cambrian Mountains, are SilurianExternal link (~430Ma old), despite the name of the hill range. The rivers in the area have swapped beds several times due to glacial activity. The upper Rheidol once was the origin of the Teifi, but was tapped into by the Ystwyth due to glacial erosion at the then head of the Ystwyth valley near Pont-rhyd-y-Groes. Later, the same process happened to the Ystwyth when the Rheidol captured the headwaters of the Ystwyth due to erosion at the Rheidol's head at the time, near Pontarfynach[1]External link. Both captures resulted in a shorter distance from the source of the Teifi-Ystwyth-Rheidol on Pumlumon to the sea, causing the formation of the Ystwyth and, later, Rheidol gorges due to faster flowing water. The original valleys of the Ystwyth and Rheidol, i.e. today's lowland sections, run along geological fault lines, and the capture points are the points where the fault lines intersect with the original Teifi valley, which can still be seen as a high-level valley (cf. thumbnails) running north to south from Pontarfynach (Rheidol) via Pont-Rhyd-y-Groes (Ystwyth) to Pontrhydfendigaid (Teifi).
Fig.:Schematic showing the successive captures of the Teifi (red) by the Ystwyth (blue) and of the Ystwyth by the Rheidol (green). Grey lines indicate abandoned valleys. (after [2]).
SN7375 : Wind Gap between the Rheidol and the Ystwyth. by Bob Bowyer
SN7374 : Bridge at  Pen-Y-Bontbren by Trix71
SN7270 : The Ystrad Meurig to Ysbyty Ystwyth road by Nigel Brown
SN7370 : Fields west of the B4343 by Nigel Brown


1:50,000 Modern Day Landranger(TM) Map © Crown Copyright
1:50,000 Modern Day Landranger(TM) Map © Crown Copyright
Further downstream, just below (west of) the Ystwyth gorge, the valley opens up and the river meanders among sandy deposits. The exact position of the river moves over time, and it splits into several arms with small islands between them ('braiding'). The ground in this section is polluted due to former lead mining activity, and the resulting lack of vegetation contributes to the continual erosion and change of the channel patterns[3]External link on a timescale of just months.SN7071 : Floodplain of the River Ystwyth near Llanafan by Angella Streluk
SN7071 : Afon Ystwyth by Row17
SN7172 : Afon Ystwyth by Brian Green


Land use in the area

SN8575 : Gors Lwyd by Stephen McKayThe source of the Ystwyth is the upland bog of Gors Lwyd. This and the first few kilometres of the head of the valley are used only for rough grazing, if at all.SN8475 : Towards the top of Cwm Ystwyth by Andrew Longton
SN8275 : Descending into Blaenycwm by Row17At Esgair-wen, where the Nant Troed-y-Rhiw meets the Ystwyth, a small area of level ground has formed between the steep hillsides, which is used for enclosed grazing.SN8275 : Blaenycwm by Rudi Winter
SN8074 : Cwmystwyth Mine complex by Rudi WinterBelow the upland farms, the steep-sided valley is dominated by disused lead mines. Pollution resulting from the mining activity results in very little vegetation growing in this area.SN8074 : Pugh's Adit, Lead Mine by Chris Andrews
SN7873 : Dol-chenog with Cwmystwyth right hand skyline. by John FieldingThe valley widens sufficiently at Cwmystwyth to allow farming on enclosed grazing land.SN7874 : Cwm Ystwyth by Stephen McKay
SN7773 : Pont Dologau by Rudi WinterThe Ystwyth gorge between Cwmystwyth and Blaen-y-Ddol is mostly covered in Forestry Commission operated woodland. Much of this area is part of the old Hafod estate and is operated as an accessible outdoor recreation area with waymarked walks at present. The village of Pont-Rhyd-y-Groes is perched on the left bank of the river, above the gorge.SN7772 : Grotto on the Hafod estate by Andrew Longton
SN7071 : Floodplain of the River Ystwyth near Llanafan by Angella StrelukBelow Blaen-y-Ddol, where the valley widens again, past use has been for more lead mining, although the environmental implications are less obvious than further up the valley.SN7172 : Disused mine near Blaen-y-ddol by Brian Green
SN6871 : White houses by Row17The coastal plain is reached at Pont Llanafan, from where agricultural use (mostly enclosed sheep and cattle farming) dominates. Trawsgoed farm, on the right bank, and some ancillary enterprises are run by the Institute of Grassland and Environmental Research, now part of Aberystwyth University.SN6774 : Trawsgoed Farm by John Lucas
SN6375 : River in Llanilar - facing Crosswoods by mattThe section of the river to the east of Llanilar has been straightened when the Caerfyrddin/Carmarthen to Aberystwyth railway lineExternal link was built in 1867 (closed since 1964). The railway alignment is now used as part of the National Cycle Route network.SN6673 : Ystwyth Trail - NCR 81/82 by Row17
SN5879 : Farmland, Ystwyth estuary by Nigel CallaghanWest of Rhydyfelin, the river emerges into what once was a broad tidal estuary, although the land has been reclaimed during the 18th century, when the river mouth was divertedExternal link to meet the Afon Rheidol at the seaward end of Aberystwyth harbour. This was achieved by placing large boulders (now making up Tan-y-Bwlch beach) across the estuary and digging a trench through a rocky bar at the foot of Dinas hill.SN5780 : Traeth Tanybwlch from Aberystwyth harbour by David Rowlands


References

[1] G Higgs, Afon Teifi at Cors Caron, Cardiganshire; in KJ Gregory, A Werritty (Eds.), Fluvial Geomorphology of Great Britain; London: Chapman & Hall, 1997, p.163ff.
[2] GM Howe, P Thomas; Welsh Landforms and Scenery; London: Macmillan, 1963
[3] G Higgs, Afon Ystwyth, Cardiganshire; in KJ Gregory, A Werritty (Eds.), Fluvial Geomorphology of Great Britain; London: Chapman & Hall, 1997, p.148ff.
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