Rhinogydd

The Rhinogydd (a Welsh plural form, often anglicised as Rhinogs and also known by the alternative Welsh plural Rhinogau) are a range of mountains located east of Harlech in North Wales. The name Rhinogydd derives from the names of two of the more famous peaks, Rhinog Fawr and Rhinog Fach, although the greatest elevation in the range is reached by Y Llethr, 756 m (2,480 feet).

The Rhinogydd are notably rocky and heather-clad towards the northern end of the range, especially around Rhinog Fawr, Rhinog Fach and towards Moel Ysgyfarnogod. The southern end of the range around Y Llethr, Diffwys and the Ysgethin Valley has a softer, grassy character.

A healthy population of feral goats can also be found in the range. Over 30 km² of the range are protected as a Special Area of Conservation and a National Nature Reserve.

The Rhinogydd are formed of hard sedimentary rocks of Cambrian age which occur as a major anticlinal structure known to geologists as the Harlech Dome. This structure which originated during the Caledonian Orogeny (mountain-building period) extends from Cadair Idris in the south to Blaenau Ffestiniog in the north. Its erosion by successive ice ages has left the valleys and peaks of the Rhinogydd visible today. The core of the area is formed from the hard-wearing greywackes of the Rhinog Formation. The formation also contains and is overlain by some siltstones and mudstones which form a broken zone of softer scenery around the periphery of the area's rugged core. In places, swarms of dolerite dykes cut through the country rocks in a generally northwest-southeast direction. Much of the lower ground is mantled by glacial till, a legacy of the last ice age.

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