Gyrn Ddu is a
hill near the northeastern corner of the
Llŷn Peninsula in the
community of
Llanaelhaearn in the county of
Gwynedd
Gwynedd (; ) is a county and preserved county (latter with differing boundaries; includes the Isle of Anglesey) in the north-west of Wales. It shares borders with Powys, Conwy County Borough, Denbighshire, Anglesey over the Menai Strait, and C ...
in North
Wales. It forms the western half of a wider upland area, another significant top of which is the 510 m summit of
Bwlch Mawr
Bwlch Mawr is a hill near the northeastern corner of the Llŷn Peninsula in the community of Clynnog in the county of Gwynedd in North Wales.
Its name is an odd one for a hill, as it means "big pass" in English. It forms the eastern half of a wi ...
to the east.
The distinct northern top of Gyrn Ddu is Gyrn Goch, which attains a height of 492 m. The summit of an eastern top which reaches 491 m is crowned by a prehistoric cairn. To the southwest of Gyrn Ddu is the lower top of Moel Pen-llechog, which reaches a height of 316 m, whilst to the south is the 416 m flat top of Moel Bronmiod.
Geology
In common with a number of other isolated hills in Llŷn, Gyrn Ddu is formed by an
igneous intrusion
In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...
of
Palaeozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and '' ...
age. The northwestern slopes of Gyn Ddu have been quarried in the past and a number of inclines descend the steep slopes beneath them .
Access
A single
public footpath
A footpath (also pedestrian way, walking trail, nature trail) is a type of thoroughfare that is intended for use only by pedestrians and not other forms of traffic such as motorized vehicles, bicycles and horses. They can be found in a wide ...
crosses the southern flanks of the hill but the larger part of the hill is mapped as
open country under the
Countryside and Rights of Way Act 2000 and therefore freely available to walkers. A further public footpath runs from the hamlet of Gyrn Goch to the edge of the open country on its northern flanks.
[Ordnance Survey Explorer map 254 'Lleyn Peninsula East/Pen Llyn Ardal Ddwyreiniol']
References
{{reflist
External links
43084283 images of Gyrn Ddu and area on Geograph website
Mountains and hills of Gwynedd
Marilyns of Wales