Craig y Llyn
|Craig y Llyn|
|Elevation||600 m (1,969 ft)|
|Prominence||392 m (1,286 ft)|
|Listing||Marilyn, council top|
|Translation||cliff of the lake (Welsh)|
|Rhigos, Cynon Valley, Rhondda Cynon Taff, Wales|
|Topo map||OS Landranger 170|
Craig y Llyn is a mountain situated in Rhigos on the west side of the upper Cynon Valley in South Wales; it is the highest point in the traditional county of Glamorgan and the highest in the South Wales Valleys. It is named from the cliffs of its steep northern escarpment which overlook Llyn Fawr.
The hill is covered by forestry, except for the steep north and northeast faces, and is crowned with a trig point. Several footpaths cross near the summit of the hill, including the Coed Morgannwg Way, and the county boundary between Neath Port Talbot and Rhondda Cynon Taff passes 200 m to the east of the summit. The highest point in Rhondda Cynon Taff, Craig y Llyn, is commonly known as the Rhigos Mountain after the village of Rhigos located on the northern side of the mountain in the Cynon Valley.
The hill is composed of a thick sequence of sandstones and mudstones assigned to the South Wales Coal Measures. The summit plateau is formed from the Pennant Sandstone of the Upper Coal Measures. The two cwms on its northern flanks which shelter Llyn Fach and Llyn Fawr are of glacial origin. A landslipped mass of rock lies above the western end of the latter lake.
- British Geological Survey 1:50,000 map sheet 231 'Merthyr Tydfil'