, 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 country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...

, subdivision_type2 = , subdivision_name2 = , subdivision_type3 = , subdivision_name3 = , subdivision_type4 = , subdivision_name4 = , subdivision_type5 = , subdivision_name5 = , length = , width_min = , width_avg = , width_max = , depth_min = , depth_avg = , depth_max = , discharge1_location= , discharge1_min = , discharge1_avg = , discharge1_max = , source1 =

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 hamle ...

, source1_location =

, source1_coordinates= , source1_elevation = , mouth = , mouth_location = Irish Sea , 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 in mid

. Its source is the

( cy, Llyn Mwyngil) just south of the Cadair Idris 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 Irish Sea to the north of

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

. 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, from where it resumes its southwesterly direction, meandering through a broad valley. It is joined here by its tributary, the Afon Fathew, which flows from near Dolgoch and joins it to the east of

, near Bryncrug. 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, 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 Cadair Idris massif to the north and the huge rock face of Craig yr Aderyn 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 Bryncrug alongside the Afon Fathew to the

Tributaries

* Nant Gwernol * Afon Cader * Afon Fathew

References

External links

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