Cadair Idris or Cader Idris is a mountain in the
Meirionnydd area of
Gwynedd
Gwynedd (; ) is a Local government in Wales#Principal areas, county and preserved county (latter with differing boundaries; includes the Isle of Anglesey) in the North West Wales, north-west of Wales. It shares borders with Powys, Conwy County B ...
, Wales. It lies at the southern end of the
Snowdonia National Park near the town of
Dolgellau. The peak, which is one of the most popular in Wales for walkers and
hikers
Hiking is a long, vigorous walk, usually on trails or footpaths in the countryside. Walking for pleasure developed in Europe during the eighteenth century.AMATO, JOSEPH A. "Mind over Foot: Romantic Walking and Rambling." In ''On Foot: A His ...
, is composed largely of
Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. ...
igneous rock
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 l ...
s, with classic
glacial erosion features such as
cwms,
moraine
A moraine is any accumulation of unconsolidated debris ( regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice sh ...
s,
striated rocks, and
roches moutonnées.
Etymology
''Cadair Idris'' means 'Idris's Chair'.
Idris Idris may refer to:
People
* Idris (name), a list of people and fictional characters with the given name or surname
* Idris (prophet), Islamic prophet in the Qur'an, traditionally identified with Enoch, an ancestor of Noah in the Bible
* Idris G ...
is usually taken to be the name of a giant or, alternatively, it may refer to Idris ap Gwyddno (or Gweiddno), a 7th-century prince of
Meirionnydd who won a battle against the Irish on the mountain.
Idris ap Gwyddno was in fact referred to as ''Idris Gawr'' ("Idris the Giant") in some mediaeval
genealogies of Meirionydd.
The basic meaning of the word ''cadair'' (
Middle Welsh
Middle Welsh ( cy, Cymraeg Canol, wlm, Kymraec) is the label attached to the Welsh language of the 12th to 15th centuries, of which much more remains than for any earlier period. This form of Welsh developed directly from Old Welsh ( cy, Hen ...
/
Early Modern Welsh ''kadeir'' or ''cadeir'') is 'seat, chair' (borrowed from the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
''cathedra'' 'chair'). In place names ''cadair'' can mean 'stronghold, fort, fortress' or 'mountain or hill shaped like a chair'. The spelling ''cader'' represents a spoken variant of the standard form ''cadair''.
It appears that ''Cadair/Cadeir Idris'' is the form used in the earliest Welsh-language sources. In a poem in his own hand in the second half of the 15th century, the poet
Lewys Glyn Cothi
Lewys Glyn Cothi (c. 1420 – 1490), also known as Llywelyn y Glyn, was a prominent 15th century Welsh poet who composed numerous poems in the Welsh language. He is one of the most important representatives of the ''Beirdd yr Uchelwyr'' ("Poets of ...
wrote 'Dros gadair idris gedy' ('and then over Cadair Idris'). Around 1600,
John Jones of Gellilyfdy referred to 'y mynydh neu bhan neu bhoel a elwir Cadeir Idris' ('the mountain, peak or hill known as Cadeir Idris').
The spoken form represented by ''cader'' had developed by the end of the Middle Ages and as a result the form ''Cader Idris'' was often used in English and Latin documents at that time and in more recent documents in English and Welsh.
In his ''Dictionarum Duplex'' published in 1632,
John Davies of Mallwyd differentiated between the two words ''cadair'' ('chair') and ''cader'' ('fort, fortress'), referring to 'Cader Idris' and 'Cader Ddinmael'. That interpretation was followed by some later
lexicographer
Lexicography is the study of lexicons, and is divided into two separate academic disciplines. It is the art of compiling dictionaries.
* Practical lexicography is the art or craft of compiling, writing and editing dictionaries.
* Theoretica ...
s, including
Thomas Charles and
Titus Lewis
Titus Lewis (21 February 1773 – 1 May 1811) was a Welsh Baptist minister and author. Lewis is notable for several important works, including the publication of ''A Welsh-English Dictionary'' (1805) and several volumes of hymns and biblical commen ...
. It is now accepted, however, that ''cader'' is a spelling of a spoken form of ''cadair'', and that there is no evidence that ''cadair'' and ''cader'' are separate words. But as it represents the pronunciation in the local dialect, the spelling ''Cader Idris'' is often seen in Welsh and English, and in June 2016
Snowdonia National Park decided to adopt that spelling on its signage, despite advice from the Welsh Language Commissioner and from Park officers, who favoured 'Cadair'. The local dialect form is also seen in the name of the local secondary school,
Ysgol y Gader. The name of the mountain is typically spelt ''Cadair Idris'' on current maps. The summit of the mountain is known as Penygader ("top of the chair/stronghold").
Ascent
There are three main trails that lead to the top of Cadair Idris. The summit, which is covered in
scree
Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. Talus deposits typically ha ...
, is marked by a
trig point
A triangulation station, also known as a trigonometrical point, and sometimes informally as a trig, is a fixed surveying station, used in geodetic surveying and other surveying projects in its vicinity. The nomenclature varies regionally: they ...
. There is also a low-standing stone shelter with a roof.
Pony Path

The Pony Path (
Welsh
Welsh may refer to:
Related to Wales
* Welsh, referring or related to Wales
* Welsh language, a Brittonic Celtic language spoken in Wales
* Welsh people
People
* Welsh (surname)
* Sometimes used as a synonym for the ancient Britons (Celtic peopl ...
: ''Llwybr Pilin Pwn''), which begins in the north from either
Dolgellau or the
Mawddach estuary, is the easiest but the longest of the main trails. Its length from the mountain's base is with a climb.
Fox's Path
The Fox's Path (
Welsh
Welsh may refer to:
Related to Wales
* Welsh, referring or related to Wales
* Welsh language, a Brittonic Celtic language spoken in Wales
* Welsh people
People
* Welsh (surname)
* Sometimes used as a synonym for the ancient Britons (Celtic peopl ...
: ''Llwybr Madyn''),This is the most direct way to the summit as the trail leads straight up the northern face. The ascent involves a climb up a
cliff
In geography and geology, a cliff is an area of rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. Cliffs are common on ...
-
scree
Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. Talus deposits typically ha ...
face. However, this part of the Fox's Path has been heavily eroded in recent years making the descent dangerous.
Minffordd Path
The Minffordd Path (
Welsh
Welsh may refer to:
Related to Wales
* Welsh, referring or related to Wales
* Welsh language, a Brittonic Celtic language spoken in Wales
* Welsh people
People
* Welsh (surname)
* Sometimes used as a synonym for the ancient Britons (Celtic peopl ...
: ''Llwybr Minffordd'') starts on the southern side of the mountain near the
glacial Tal-y-llyn Lake. Hikers using this ascent climb past Llyn Cau and along the rim of Craig Cau (rockwall) to Penygadair. Its length is and involves two climbs of over .
Geology

Cadair Idris is formed from a complexly fractured and
folded pile of both
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 particle ...
s and
igneous rock
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 l ...
s of
Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. ...
age. They comprise the
mudstones and
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, ...
s of the Ceiswyn Formation which form much of the southern part of the mountain, together with the varied rocks of the underlying
Aran Volcanic Group
The Aran Volcanic Group is a geologic group in Wales. It preserves fossils dating back to the Ordovician period.
See also
* List of fossiliferous stratigraphic units in Wales
This is a list of fossiliferous stratigraphic units in Wales.
...
. The steep cliffs rising above Llyn Cau to the north are formed from hard-wearing
basalt
Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% of a ...
s and
tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock ...
s of the Pen y Gadair Volcanic Formation whilst those on the south side are acid tuffs of the Craig Cau Formation. The imposing cliffs which characterise the north side of the mountain are formed from a micro
granite
Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies und ...
intruded into the Ty'r Gawen mudstones. In common with the rest of Snowdonia, the faulting and folding of this rock succession took place during the
Caledonian Orogeny
The Caledonian orogeny was a mountain-building era recorded in the northern parts of the British Isles, the Scandinavian Mountains, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that oc ...
.
The crater-like shape of Cwm Cau has given rise to the occasional mistaken claim that Cadair Idris is an
extinct volcano (though as noted above, some of its bedrock is volcanic in origin). This theory was discounted as early as 1872, when
Charles Kingsley
Charles Kingsley (12 June 1819 – 23 January 1875) was a broad church priest of the Church of England, a university professor, social reformer, historian, novelist and poet. He is particularly associated with Christian socialism, the workin ...
commented in his book ''Town Geology'':
The natural bowl-shaped depression to which the name of ''chair'' has been attached, was formed by a
cirque glacier during multiple
ice age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gre ...
s when snow and ice accumulated on these slopes partly through
avalanching. The glacier was up to a square kilometre in size surrounded on three sides by steep cliffs the highest being the headwall. The ''chair'' of Cadair Idris is this bowl-shaped hollow in the bedrock formed by the movement of glacial ice across the floor of the hollow,
abrading it and the lip over which it then flowed.
There are several tear-drop shaped knolls above the edge of Llyn Cau, each of which is a
roche moutonnée
In glaciology, a roche moutonnée (or sheepback) is a rock formation created by the passing of a glacier. The passage of glacial ice over underlying bedrock often results in asymmetric erosional forms as a result of abrasion on the "stoss" (upstr ...
formed by the abrasive action of the moving ice. The two highest lakes are Llyn Cau and Llyn y Gader; the latter is thought to have a maximum depth of about .
Much of the area around Cadair Idris was designated a
National Nature Reserve in 1957, and is home to
Arctic–alpine plants such as
purple saxifrage and
dwarf willow.
Myths, legends and popular culture

There are numerous legends about Cadair Idris. Some nearby lakes are supposed to be bottomless, and anyone who sleeps on its slopes alone will supposedly awaken either a madman or a poet. This tradition (of sleeping on the summit of the mountain) apparently stems from bardic traditions, where bards would sleep on the mountain in hope of inspiration.
Although the mountain's name is typically taken to refer to the mythological giant
Idris Idris may refer to:
People
* Idris (name), a list of people and fictional characters with the given name or surname
* Idris (prophet), Islamic prophet in the Qur'an, traditionally identified with Enoch, an ancestor of Noah in the Bible
* Idris G ...
, who was said to have been skilled in poetry, astronomy and philosophy,
it has sometimes been mistranslated as ''Arthur's Seat'', in reference to
King Arthur (and to the
hill of the same name in Edinburgh),
an idea used by author
Susan Cooper in her book ''
The Grey King''. However, this translation is mistaken and there is no etymological or traditional connection between Idris and Arthur.
In Welsh mythology, Cadair Idris is also said to be one of the hunting grounds of
Gwyn ap Nudd and his
Cŵn Annwn. The howling of these huge dogs foretold death to anyone who heard them, the pack sweeping up that person's
soul
In many religious and philosophical traditions, there is a belief that a soul is "the immaterial aspect or essence of a human being".
Etymology
The Modern English noun '':wikt:soul, soul'' is derived from Old English ''sāwol, sāwel''. The ea ...
and herding it into
the underworld.
The mountain is mentioned several times and is used as a backdrop to the story of
Mary Jones and her Bible. This story is an account of a girl from
Llanfihangel-y-Pennant at the foot of the mountain who walked 25 miles to
Bala
Bala may refer to:
Places
India
*Bala, India, a village in Allahabad, India
* Bala, Ahor, a village in the Jalore district of Rajasthan
* Bala, Raebareli, a village in Uttar Pradesh, India
Romania
* Bala, Mehedinți, a commune in Mehedinţi ...
in order to buy a bible, which were scarce at the time. Jones' determined journey to get hold of a copy of the book in 1800 was a major factor behind the foundation of the
British and Foreign Bible Society
The British and Foreign Bible Society, often known in England and Wales as simply the Bible Society, is a non-denominational Christian Bible society with charity status whose purpose is to make the Bible available throughout the world.
The S ...
in 1804.
"Tongues of fire on Idris flaring" is mentioned in the opening verse of the John Guard version of the song "
Men of Harlech".
In
Cassandra Clare
Judith Lewis (née Rumelt; born July 27, 1973), better known by her pen name Cassandra Clare, is an American author of young adult fiction, best known for her bestselling series ''The Mortal Instruments''.''
Personal life
Clare was born Judith ...
's ''
Clockwork Princess
''Clockwork Princess'' is a 2013 fantasy novel written by young adult author, Cassandra Clare. It is the third and final installment of ''The Infernal Devices'' trilogy, following the first book, ''Clockwork Angel,'' and the second book, ''Clockw ...
'' Idris is where final battle between the protagonists and antagonist takes place.
References
External links
Information about Cadair Idris*Computer generated summit panorama
NorthSouth
A description of and guide to climbing Cadair Idris from h2g2
Cadair Idris Walk Via the Pony Path
Cadair Idris Long Walk from Llanfihangel-y-pennant
Summary of the Walks up Cader Idris
Walking on Cadair Idris - Inside Welsh Sport
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Arthog
Dolgellau
Abergynolwyn
Llanfihangel-y-Pennant
Mountains and hills of Gwynedd
Sites of Special Scientific Interest in East Gwynedd
Mountains and hills of Snowdonia
Hewitts of Wales
Landmarks in Wales
Marilyns of Wales
National nature reserves in Wales
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