River Ely
river in south Wales
The River Ely (Welsh: Afon Elái) is in South Wales flowing generally southeast, from Tonyrefail to Cardiff.
The river is about 24 miles (39 km) long. The Ely's numerous sources lie in the mountains to the south of Tonypandy, near the town of Tonyrefail, rising in the eastern slopes of Mynydd Penygraig (Penygraig) and Mynydd y Gilfach (Penrhiwfer) and the western slopes of Mynydd Dinas (Williamstown), whose eastern slopes feed the Rhondda by Porth. The source of the Ogwr Fach lies just to the west.
After flowing through Tonyrefail and through the grounds of the Royal Glamorgan Hospital at Ynysmaerdy, it follows the A4119 road through the valley pass formed between Mynydd Garthmaelwg,
to the west and Llantrisant, to the east. Flowing through Talbot Green, the Ely is joined by the Afon Clun at Pontyclun. Although numerous smaller streams join the river, the Clun is its only large tributary.
The Ely turns to the southeast on reaching the Vale of Glamorgan alongside the South Wales Main Line immediately south of Miskin, and after being traversed by the M4 motorway, it flows through farmland. It passes the St Fagans National History Museum and continues towards Cardiff and Ely (Welsh: Trelái) before flowing under the Vale of Glamorgan Line and into Cardiff Bay at Penarth Marina.
The Ely Subway is a closed pedestrian tunnel under the mouth of the Ely.
The public source identifies “River Ely” as river in south Wales. This brief keeps that definition visible, then builds a research path around River, river and south.
Why this record matters
A short description can identify a subject without explaining its stakes. For “River Ely”, the useful work is to connect “river in south Wales” to the records capable of establishing context and consequence.
Maps, plans, fabric surveys and administrative records can establish how the site’s name, extent and function changed over time. The source revision retrieved here is dated Sep 7, 2026. The linked authority identifier is Q3398402. Authority coordinates are 51.450, -3.167. 1 of 2 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank.
A single description cannot reconcile every naming convention, rebuilding phase or administrative transfer associated with a place. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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Treat names, boundaries and functions as historically changeable. Maps, plans, inventories and administrative records can clarify what the place meant at different dates.
- Historic place names
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Contemporary maps, plans, listed-building records, estate papers and the responsible local or national archive.
Three-step research path
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Questions for further research
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This entry incorporates text from “River Ely” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.