, name_etymology = , image = Afon Dysynni & Morfa Gwyllt - geograph.org.uk - 194680.jpg , image_size = , image_caption = Dysynni estuary , map = , map_size = , map_caption = , pushpin_map = , pushpin_map_size = , pushpin_map_caption= , subdivision_type1 = Country , subdivision_name1 =

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 ...

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Tal-y-llyn Lake Tal-y-llyn Lake, ( cy, Llyn Mwyngil), also known as Talyllyn Lake and Llyn Myngul, is a large glacial ribbon lake in Gwynedd, North Wales. It is formed by a post-glacial massive landslip damming up the lake within the glaciated valley. The haml ...

, source1_location =

, source1_coordinates= , source1_elevation = , mouth = , mouth_location =

Irish Sea The Irish Sea or , gv, Y Keayn Yernagh, sco, Erse Sie, gd, Muir Èireann , Ulster-Scots: ''Airish Sea'', cy, Môr Iwerddon . is an extensive body of water that separates the islands of Ireland and Great Britain. It is linked to the Ce ...

, mouth_coordinates = , mouth_elevation = , progression = , river_system = , basin_size = , tributaries_left = , tributaries_right = , custom_label = , custom_data = , extra = The River Dysynni ( cy, Afon Dysynni) is a

river A river is a natural flowing watercourse, usually freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the ...

in mid

. Its source is the

( cy, Llyn Mwyngil) just south of the

Cadair Idris Cadair Idris or Cader Idris is a mountain in the Meirionnydd area of Gwynedd, Wales. It lies at the southern end of the Snowdonia National Park near the town of Dolgellau. The peak, which is one of the most popular in Wales for walkers and hi ...

massif and its mouth is in the

Cardigan Bay Cardigan Bay ( cy, Bae Ceredigion) is a large inlet of the Irish Sea, indenting the west coast of Wales between Bardsey Island, Gwynedd in the north, and Strumble Head, Pembrokeshire at its southern end. It is the largest bay in Wales. Geo ...

area of the

to the north of

Tywyn Tywyn (Welsh language, Welsh: ; in English language, English often ), formerly spelled Towyn, is a town, community (Wales), community, and seaside resort on the Cardigan Bay coast of southern Gwynedd, Wales. It was previously in the histo ...

. It measures about in length. Dysynni estuary 01

Course

The River Dysynni flows from the western end of

in a southwesterly direction to its confluence with the Nant Gwernol at

Abergynolwyn Abergynolwyn ( en, Mouth of the River with a Whirlpool) is a village in southern Gwynedd, Wales, located at the confluence of the Nant Gwernol and the Afon Dysynni. The population of the community which is named after the village of Llanfihan ...

. From here it flows in a northwesterly direction to its confluence with the

Afon Cader This is a list of rivers of Wales, organised geographically. It is taken anti-clockwise from the Dee Estuary to the M48 Bridge that separates the estuary of the River Wye from the River Severn. Tributaries are listed down the page in an upstre ...

, from where it resumes its southwesterly direction, meandering through a broad valley. It is joined here by its tributary, the

Afon Fathew The Afon Fathew ( en, River Mathew/Fathew) is a river in Gwynedd, north-west Wales. The river is downstream from the Dolgoch Falls which is a popular nature site, and is followed for much of its course by the Talyllyn Railway. Name The basi ...

, which flows from near Dolgoch and joins it to the east of

, near

Bryncrug Bryncrug (), sometimes spelt Bryn-crug, is a village and community in Gwynedd, Wales. Afon Fathew flows through the village and into the River Dysynni. The village is situated to the north east of the town of Tywyn, at the junction of the A49 ...

. The river enters

through the

Broad Water Broad Water, or Broadwater (Welsh: ''Aber Dysynni'') is a salt water lagoon near Tywyn, Wales formed from the silted up estuary of the River Dysynni. In the eighteenth and nineteenth centuries, the estuary was used by the shipbuilding industry, ...

lagoon to the north of Tywyn, near Tonfanau. The river is interesting geologically because it exhibits

river capture Stream capture, river capture, river piracy or stream piracy is a geomorphological phenomenon occurring when a stream or river drainage system or watershed is diverted from its own bed, and flows instead down the bed of a neighbouring stream. T ...

. This is likely to be as a result of river damming during a glacial period. The upper course of the river follows a

fault line In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

but at Abergynolwyn must have been blocked by a major

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

, the scar from which can still be seen on the side of the valley. The valley below here is blocked by debris on a rock base. The River Dysynni was thus forced to adopt a new course, and pushed its way through the hills northwestwards to find a new course in the parallel valley to the north.

Walking

The Dysynni Valley is popular with walkers. It is a scenic valley, with the

massif to the north and the huge rock face of

Craig yr Aderyn Craig yr Aderyn ( en, "Bird's Rock") is a hill rising to a height of above sea level on the south bank of the River Dysynni near Llanfihangel-y-Pennant in the county of Gwynedd, north-west Wales. Craig yr Aderyn has been designated as a Site o ...

to the south. The valley contains the ruins of

Castell y Bere Castell y Bere is a Welsh castle near Llanfihangel-y-pennant in Gwynedd, Wales. Constructed by Llywelyn the Great in the 1220s, the stone castle was intended to maintain his authority over the local people and to defend the south-west part of ...

near Llanfihangel-y-Pennant. There are several walking routes, one being a path from

alongside the Afon Fathew to the

Tributaries

* Nant Gwernol *

References

External links

www.geograph.co.uk : photos of the River Dysynni
{{authority control Abergynolwyn Bryncrug Llanfihangel-y-Pennant Llangelynin, Gwynedd Tywyn Dysynni Dysynni