Moel Oernant is a high
hill
A hill is a landform that extends above the surrounding terrain. It often has a distinct Summit (topography), summit.
Terminology
The distinction between a hill and a mountain is unclear and largely subjective, but a hill is universally con ...
in the
community
A community is a social unit (a group of living things) with commonality such as place, norms, religion, values, customs, or identity. Communities may share a sense of place situated in a given geographical area (e.g. a country, village, tow ...
of
Trawsfynydd
Trawsfynydd (; Welsh for "across hemountain") is a linear village in Gwynedd, Wales, near Llyn Trawsfynydd reservoir, and adjacent to the A470 north of Bronaber and Dolgellau and 10 km (6 miles) south of Blaenau Ffestiniog.
The total com ...
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
Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...
. It has a number of western tops, the highest of which reaches a height of overlooking the waterbody known as Llyn Gelli-Gain and another at Frîdd Wen exceeds . To the south of the lake is the top of Pîg Idris which reaches 429m. The minor top of Y-Foel attains 430m to the northeast of Moel Oernant.
Geology
The hill is formed largely from the
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...
s,
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...
and
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
s of the Maentwrog Formation and the siltstones of the underlying Clogau Formation, component units of the
Mawddach Group
The Mawddach Group is a middle to upper Cambrian lithostratigraphy, lithostratigraphic group (stratigraphy), group (a sequence of rock strata) in Gwynedd, Wales. The name is derived from the river known as the Afon Mawddach.
Outcrops
The rocks a ...
of
Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...
age
sedimentary rock
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
s. Sandstones and siltstones of the Gamlan Formation of the
Harlech Group are also present. An
igneous
Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or ...
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
microtonalite lies to the west of the summit and the whole hill is cross-cut by
dykes of similar material and later
dolerite
Diabase (), also called dolerite () or microgabbro,
is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained ...
. Some
quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...
vein
mineralization
Mineralization may refer to:
* Mineralization (biology), when an inorganic substance precipitates in an organic matrix
** Biomineralization, a form of mineralization
** Mineralization of bone, an example of mineralization
** Mineralized tissues are ...
is recorded within the microtonalite outcrop. A number of
faults criss-cross the area, the most significant of which is the broadly north–south aligned Craiglaseithin Fault which runs through the summit of the 466m top. The lower slopes are mantled with a patchy cover of
glacial till
image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
.
Access
A
public bridleway continuing as a
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 ...
runs from Cwm Prysor southwest across the northern and western flanks of the hill towards Trawsfynydd. Other than parts of its northern slopes the entire hill is mapped as
open country under the
Countryside and Rights of Way Act 2000 and therefore freely available for public access on foot. Along its southern and eastern margin is a minor public road beside the
Afon Gain.
[Ordnance Survey Explorer map OL18 Harlech, Porthmadog & Bala/Y Bala]
References
{{reflist
External links
43084293 images of Moel Oernant and area on Geograph website
Trawsfynydd
Mountains and hills of Gwynedd
Mountains and hills of Snowdonia