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Image:Geological map of Great Britain.jpg
Geological map of Great Britain showing Wales in the South West. The Ordovician and Silurian rocks are pale buff and pink, the Old Red Sandstone dark orange, the Coal Measures grey and igneous rocks red patches.

Wales is a peninsula in the south-west of the island of Great Britain. A peninsula is a piece of land that is nearly surrounded by Water but connected to Mainland via an Isthmus. See also Kingdom of Great Britain Great Britain (Breatainn Mhòr Prydain Fawr Breten Veur Graet Breetain is the larger of the two main islands The entire area of Wales is about 20,779 km² (8,023 square miles). Square Kilometre ( US spelling square kilometer) symbol km2, is a decimal multiple of the SI unit of The square mile is an imperial and US unit of Area equal the area of a square of one statute mile. It is about 274 km (170 miles) north-south and 97 km (60 miles) east-west. The kilometre ( American spelling: kilometer) symbol km is a unit of Length in the Metric system, equal to one thousand A mile is a unit of Length, usually used to measure Distance, in a number of different systems including Imperial units United States This is about the direction for other uses see North (disambiguation. South is one of Cardinal directions and is opposite to the North. The Experimental Advanced Superconducting Tokamak (EAST internal designation HT-7U is an experimental Superconducting Tokamak Magnetic fusion energy This article refers to the cardinal direction for other uses see West (disambiguation. Wales is bordered by England to the east and by sea in the other three directions: the Welsh Channel to the south, St George's Channel to the west, and the Irish Sea to the north. England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland The Bristol Channel ( Môr Hafren) is a major inlet in the island of Great Britain, separating South Wales from Devon and Somerset St George's Channel ( Welsh: Sianel San Siôr, Irish Muir Bhreatan) is a channel The Irish Sea ( Irish: Muir Éireann or Muir Meann; Scottish Gaelic: Muir Eireann Welsh: Môr Iwerddon, Together, Wales has over 1,200km (750 miles) of coastline. There are several islands off the Welsh mainland, the largest being Ynys Môn (Anglesey) in the north west. This is a list of the Islands of Wales, the mainland of which is part of Great Britain, as well as a table of the largest Welsh islands by area History There are numerous Megalithic monuments and Menhirs present on Anglesey testifying to the presence of mankind in prehistory

Wales is mountainous, particularly in the north and central regions. A mountain is a Landform that extends above the surrounding Terrain in a limited area with a peak The mountains were shaped during the last ice age, the Devensian glaciation. An ice age is a period of long-term reduction in the Temperature of the Earth 's surface and atmosphere resulting in an expansion of continental Ice sheets "Last glacial" redirects here For the period of maximum glacier extent during this time see Last Glacial Maximum The last glacial period The highest mountains in Wales are in Snowdonia (Eryri), and include Snowdon (Yr Wyddfa), which, at 1085 m (3,560 ft) is the highest peak in Wales. Snowdonia (Eryri is a region of North Wales and a National park of in area For other meanings see Snowdon (disambiguation. Snowdon (Yr Wyddfa is the highest Mountain in Wales and the third The Brecon Beacons (Bannau Brycheiniog) are in the south and are joined by the Cambrian Mountains in mid-Wales, the latter name being given to the earliest geological period of the Paleozoic era, the Cambrian. The Brecon Beacons (Bannau Brycheiniog is a Mountain range located in the south-east of Wales. The Cambrian Mountains are a series of Mountain ranges in Wales, reaching from and including the South Wales mountains of the Brecon Beacons The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life" The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with

In the mid-nineteenth century, two prominent geologists, Roderick Murchison and Adam Sedgwick used their studies of the geology of Wales to establish certain principles of stratigraphy and palaeontology. Sir Roderick Impey Murchison 1st Baronet KCB FRS ( 19 February, 1792 &ndash 22 October, 1871) was an influential Adam Sedgwick ( 22 March 1785 &ndash 27 January 1873) was one of the founders of modern Geology. Stratigraphy, a branch of Geology, studies rock layers and layering ( stratification) Palaeontology redirects here For the Scientific journal, see Palaeontology (journal. After much dispute, the next two periods of the Paleozoic era, the Ordovician and Silurian, were named after ancient Celtic tribes from this area. The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443

Contents

Tectonics of Avalonia

The remaining rocks of Avalonia within Europe. It indicates the part which collided with Baltica in the upper Ordovician and that which collided with Laurentia in the Silurian.
The remaining rocks of Avalonia within Europe. It indicates the part which collided with Baltica in the upper Ordovician and that which collided with Laurentia in the Silurian.

Avalonia was an ancient microcontinent or terrane whose history formed much of the older rocks of Western Europe. Avalonia was an ancient Microcontinent or Terrane whose history formed much of the older rocks of Western Europe, Atlantic Canada and parts of the Continental crustal fragments or microcontinents are fragments of continents thought to have been broken off from the main continental mass forming distinct islands possibly A terrane in Geology is a fragment of crustal material formed on or broken off from one Tectonic plate and accreted — " sutured " The name is derived from the Avalon Peninsula in Newfoundland. The Avalon Peninsula is a large Peninsula (10360 km²) that makes up the southeast portion of the island of Newfoundland. Newfoundland — ˈn(jufənˌlænd (Terre-Neuve Talamh an Éisc — is a large island 15 km off the east coast of Wales was entirely contained within the Avalonian block, and shares its tectonic chronology.

In the early Cambrian, the supercontinent Pannotia broke up and Avalonia drifted off northwards from Gondwana. The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with In Geology, a supercontinent is a Landmass comprising more than one Continental core or Craton. Pannotia, first described by Ian W D Dalziel in 1997 is a hypothetical Supercontinent that existed from the Pan-African orogeny about 600 million years ago to the Gondwana (ɡɒnˈdwɑːnə originally Gondwanaland) was a southern Supercontinent that existed about 500 to 200 Ma ago This independent movement of Avalonia started from a latitude of about 60° South. The eastern end of Avalonia collided with Baltica, a continental plate occupying the latitudes from about 30°S to 55°S, as the latter slowly rotated anticlockwise towards it. Baltica redirects here For the Russian beer, see Baltika Breweries Baltica is a name applied by geologists to a late- Proterozoic, This happened at the end of the Ordovician and during the early Silurian. The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443

In the late Silurian and lower Devonian, the combined Baltica and Avalonia collided progressively, with Laurentia, beginning with the long extremity of Avalonia which is now attached to America. The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 The Devonian is a geologic period and system of the Paleozoic era spanning from to  million years ago. Laurentia (also known as the North American craton) like all Craton land was created as continents moved about the surface of the Earth The result of this was the formation of Euramerica. Euramerica (also known as Laurussia or Old Red Continent) was a minor Supercontinent created in the Devonian as the result of a collision between At the completion of this stage, the site of Britain was at 30°S and Nova Scotia at about 45°S. This collision is represented by the Caledonian folding or in North America as an early phase in the Acadian orogeny. The Caledonian orogeny is a mountain building event recorded in the Mountains and Hills of northern Scotland, Ireland, England, The Acadian orogeny is a middle Paleozoic deformation especially in the northern Appalachians, between New York and Newfoundland.

In the Permian, the new continent and another terrane, Armorica which included Iberia, drifted in from Gondwana, trapping Avalonia between it and the continent so adding Iberia/Armorica to Euramerica. The Permian is a geologic period and system that extends from 299 This was followed up by the arrival of Gondwana. The effects of these collisions are seen in Europe as the Variscan folding. The Variscan (or Hercynian) orogeny is a geologic mountain-building event caused by Late Paleozoic Continental collision between Laurasia In North America it shows as later phases of the Acadian orogeny. This was happening at around the Equator during the later Carboniferous, forming Pangaea in such a way that Avalonia was near its centre but partially flooded by shallow sea. The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 Pangaea, Pangæa or Pangea (pænˈdʒiːə from παν pan, meaning entire, and Γαῖα Gaea, meaning Earth in

In the Jurassic, Pangaea split into Laurasia and Gondwana, with Avalonia as part of Laurasia. The Jurassic is a geologic period and system that extends from about Ma (million years ago to  Ma that is from the end of the Triassic to the beginning Laurasia (lɔˈreɪʃiə lɔˈreɪʒə was a Supercontinent that most recently existed as a part of the split of the Pangaean supercontinent in the late Mesozoic In the Cretaceous, Laurasia broke up into North America and Eurasia with Avalonia split between them. The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of For the superstate in George Orwell 's novel see Nations of Nineteen Eighty-Four.

Regions of Wales

North Wales - Snowdonia may be divided into four areas. Snowdonia (Eryri is a region of North Wales and a National park of in area The northernmost area includes (west to east): Moel Hebog, Mynydd Mawr and the Nantlle Ridge; the Snowdon massif; the Glyderau, and the Carneddau. |} Moel Hebog ( Welsh: Bare Hill of the Hawk) is a Mountain in Snowdonia, north Wales which dominates the view west from the village Mynydd Mawr ( Welsh for big mountain) is a Mountain in Snowdonia, North Wales, situated approximately 7  km (4  The Nantlle Ridge is the name given to a small range of mountains in Snowdonia, north Wales which runs south-west from the village of Rhyd Ddu for The Snowdon Massif is one of the three mountain groups in Snowdonia, north Wales to include mountains over 3000 feet (914  m) high If you were looking for the Irish hard rock band see Glyder The Glyderau (a Welsh plural form also known in English The Carneddau (lit "the Cairns quot Carneddau is a Welsh plural form and is sometimes anglicised to Carnedds) are a group of These last three groups are the highest mountains in Wales, and include all Wales' 3000-foot mountains. This is a list of what is known as the Welsh 3000s, ie those 15 mountains which have a height of 3000 ft (914

The second area includes peaks such as Moel Siabod, Cnicht, the Moelwynion, and the mountains around Blaenau Ffestiniog. Moel Siabod is a Mountain in Snowdonia, North Wales, which sits isolated above the villages of Betws-y-Coed and Capel Curig. Cnicht is a Mountain in Snowdonia which forms part of the Moelwynion mountain range The Moelwynion (a Welsh Plural, sometimes anglicised to Moelwyns) are a group of Mountains in central Snowdonia. Blaenau Ffestiniog is a small Town in Gwynedd, north-west Wales.

The third area includes the Rhinogydd in the west as well as the Arenig and the Migneint (this last being an area of bog). The Rhinogydd (a Welsh plural form often Anglicised as Rhinogs and also known by the alternative Welsh plural Rhinogau) are a range of In Geology, the Arenig group is the name applied to the lowest stage of the Ordovician System The Migneint (ˈmɪgnaint in Welsh) is a large expanse of Moorland in central Snowdonia, North Wales.

The southernmost area includes Cadair Idris, the Tarren range, and the Aran group, including Aran Fawddwy, the highest mountain in the United Kingdom south of Snowdon. |} Cadair Idris or Cader Idris is a Mountain in the Snowdonia National Park, in Gwynedd, northwest Wales. Aran Fawddwy is a Mountain in southern Snowdonia, North Wales, Wales, United Kingdom.

Snowdon and its vicinity form a syncline of Ordovician rocks which are partly volcanic. In Structural geology, a syncline is a downward-curving fold, with layers that dip toward the center of the structure The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 Snowdon itself is largely formed of volcanic ash (tuff) with some sedimentary rock and igneous intrusions. Tuff (from the Italian "tufo" is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. Cadair Idris is also largely formed of Ordovician igneous rocks. The Harlech Dome, which includes the Rhinogydd, is formed of Cambrian gritstones and mudstones. In Geology, a dome is a deformational feature consisting of symmetrically-dipping Anticlines their general outline on a geologic Map is circular or oval The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with

Elsewhere in North Wales, Pre-Cambrian rocks occur in Anglesey, while the Berwyn range consists mainly of Ordovician sedimentary strata. The Precambrian ( Pre-Cambrian) is an informal name for the supereon comprising the eons of the Geologic timescale that came before the current History There are numerous Megalithic monuments and Menhirs present on Anglesey testifying to the presence of mankind in prehistory The Berwyn range ( Welsh: Y Berwyn or Mynydd y Berwyn) is an isolated and sparsely-populated area of moorland located in the north-east of Wales Carboniferous Limestone occurs north of Llangollen and the Coal Measures near Wrexham. Carboniferous Limestone is a type of Limestone rock, which was laid down in Great Britain and Ireland in the Dinantian stage Llangollen (ɬaŋ'ɡoɬɛn is a small town in Denbighshire, north-east Wales, situated on the River Dee and on the edge of the Berwyn The Coal Measures is a lithostratigraphical term used mainly in the British Isles for the coal-bearing part of the Upper Carboniferous System Wrexham (Wrecsam is a town and principal area in Wales. It is the largest town in North Wales and lies to the east of the region

Ordovician and Silurian sediments folded in the Caledonian Orogeny cover much of Wales, north and south. The Caledonian orogeny is a mountain building event recorded in the Mountains and Hills of northern Scotland, Ireland, England,

South Wales has a written record of geological interest going back to the 1100s when Giraldus Cambrensis noted pyritous shales near Newport. South Wales is an area with many features of outstanding interest to Geologists who have for long used the area for University field trips Gerald of Wales (c 1146 &ndash c 1223 also known as Gerallt Gymro in Welsh or Giraldus Cambrensis in Latin, Shale (also called mudstone) is a fine-grained Sedimentary rock whose original constituents were Clay minerals or Muds It is characterized by Newport (Casnewydd is a city and principal area in Wales, in the United Kingdom. George Owen in 1603 correctly identified the stratigraphic relationship between the Carboniferous Limestone and the Coal Measures. George Owen of Henllys ( 1552 - August 26, 1613) was a Welsh Antiquarian, author and naturalist. Some of the first published representations of fossils were those of fossil plants taken from coal measures near Neath (Gibson late 1600s). FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. The Coal Measures is a lithostratigraphical term used mainly in the British Isles for the coal-bearing part of the Upper Carboniferous System Neath (Castell-nedd is a Town and community situated in the principal area of Neath Port Talbot, Wales, UK with a Adam Sedgwick and Roderick Murchison did fundamental work on Old Red Sandstone and the underlying rocks. Adam Sedgwick ( 22 March 1785 &ndash 27 January 1873) was one of the founders of modern Geology. Sir Roderick Impey Murchison 1st Baronet KCB FRS ( 19 February, 1792 &ndash 22 October, 1871) was an influential The Old Red Sandstone is a Rock formation of considerable importance to early Paleontology.

Several successive periods are represented. Pembrokeshire has outcrops of both Pre-Cambrian and Cambrian rocks. Geography Pembrokeshire is a maritime County, bordered by the sea on three sides by Ceredigion (Cardiganshire to the northeast and by The Precambrian ( Pre-Cambrian) is an informal name for the supereon comprising the eons of the Geologic timescale that came before the current The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with A notable feature of the Ordovician system is a major downwarp known as the Welsh geosyncline. The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 Depression in Geology is a Landform sunken or depressed below the surrounding area Silurian rocks, largely mudstones and siltstones, are widely distributed in south Wales and are well displayed on the Cardiganshire coast. The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 Cardiganshire (Sir Aberteifi was an ancient county of Wales created in 1282 Carboniferous Limestone outcrops occur in south Pembrokeshire, Gower, the Vale of Glamorgan and the north and east sides of the coalfield. Geography Pembrokeshire is a maritime County, bordered by the sea on three sides by Ceredigion (Cardiganshire to the northeast and by Geography It has been a County borough (unitary authority since 1996, previously being part of South Glamorgan county The South Wales Coalfield is a large region of South Wales that is rich with Coal deposits

One of the geological rarities of south Wales is the coastline of Ogmore-by-Sea and Southerndown. Ogmore-by-Sea ( Welsh: Aberogwr - Aber Mouth + Ogwr River Ogmore is a seaside village in the Vale of Glamorgan, Wales. Southerndown is a village in Wales and suburb of Bridgend close to St Brides Major, Llantwit Major and Ogmore-by-Sea, mostly known for its beach (officially Its cliffs are composed of Sutton stone; a very rare freestone that is a banded mixture of lias limestone which contains large elements of Carboniferous limestone. In Geography and Geology, a cliff is a significant vertical or near vertical rock exposure Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 Sutton stone has always been highly regarded: as well as being used in construction throughout the Vale of Glamorgan, it was also shipped over the Bristol Channel to North Devon and North Cornwall which are both deficient in limestone. The Bristol Channel ( Môr Hafren) is a major inlet in the island of Great Britain, separating South Wales from Devon and Somerset This article is about the region of England For the breed of cattle see North Devon cattle. Housing On 9th January 2008 the ‘Regional Spatial Strategy for the South West’ (RSS announced plans to massively increase house-building in Cornwall stating that almost 70000

A major geological feature of the Upper Carboniferous sub-period in south Wales is the south Wales coalfield syncline. The South Wales Coalfield is a large region of South Wales that is rich with Coal deposits In Structural geology, a syncline is a downward-curving fold, with layers that dip toward the center of the structure The rocks comprising this important area were laid down during the Westphalian Geological Series (or epoch) approximately 314-308 million years ago (Ma), when climatic conditions were equatorial. This Westphalian succession includes a sequence with a thickness of more than 1800m in the west. The Coal Measures were laid down on a low-lying waterlogged plain with peat mires immediately south of an ancient geological feature known as the Wales-London-Brabant High.

The Brecon Beacons are a mountain range located in the south-east of Wales, forming the nucleus of the Brecon Beacons National Park (Parc Cenedlaethol Bannau Brycheiniog). The Brecon Beacons (Bannau Brycheiniog is a Mountain range located in the south-east of Wales. The Brecon Beacons (Bannau Brycheiniog is a Mountain range located in the south-east of Wales. The range consists of the mountains to the south of Brecon. The highest of these is Pen y Fan (886 m); other notable summits include Corn Du (873 m), Cribyn (795 m), and Fan y Bîg (719 m). These summits form a long ridge which forms a horseshoe around the head of the Taf Fechan river to the south-east, with long parallel spurs extending to the north-east. The Brecon Beacons are made of Devonian Old Red Sandstone. The Devonian is a geologic period and system of the Paleozoic era spanning from to  million years ago. The Old Red Sandstone is a Rock formation of considerable importance to early Paleontology.

Cefn Bryn (English: Ridge Hill) is a 5 mile long Old Red Sandstone ridge in the heart of the Gower peninsula. Cefn Bryn (Ridge Hill is a 5 mile long Old Red Sandstone Ridge in the heart of the Gower peninsula in Wales. English is a West Germanic language originating in England and is the First language for most people in the United Kingdom, the United States A ridge is a geological feature that features a continuous elevational crest for some distance The highest point on the ridge (186m) is the second highest point in Gower. The grassland on the ridge is known as Cefn Bryn Common.

Cefn-cerig Road near Cefn-cerig Farm, Llandovery, Wales, is the location of the Global Boundary Stratotype Section and Point (GSSP) which marks the boundary between the Aeronian and Telychian stages of the Silurian period on the geologic time scale. Cefn-cerig Road, a road near Cefn-cerig Farm Llandovery, Wales, is the location of the Global Boundary Stratotype Section and Point (GSSP which marks Llandovery ( Llanymddyfri) is a Market town in Carmarthenshire, Wales, lying on the River Tywi and the A40 road. A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon stratigraphic section which serves as the reference section for The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other The GSSP was ratified in 1984.

The boundary is defined as a point immediately above the highest record of the brachiopod Eocoelia intermedia and below the first appearance of the succeeding species Eocoelia curtisi. Brachiopods (from Latin brachium, arm + New Latin -poda, foot are a small phylum of Benthic Invertebrates Also First appearance datum is a term used by Geologists and paleontologists to designate the first (oldest appearance of a species in the geologic record The boundary also corresponds to the incoming of the acritarchs Deunffia monospinosa, Domasia bispinosa and Pterospermella. Acritarchs are small organic Fossils present from approximately to the present The section, part of the Wormwood Formation, is sandstone and siltstone. Sandstone is a Sedimentary rock composed mainly of Sand -size Mineral or rock grains. Siltstone is a Sedimentary rock which has a composition intermediate in grain size between the coarser Sandstones and the finer Mudstones and

Trefawr Track, a forestry road north of Cwm-coed-Aeron Farm, Llandovery, Wales, is the location of the Global Boundary Stratotype Section and Point (GSSP) which marks the boundary between the Rhuddanian and Aeronian stages of the Silurian period on the geologic time scale. Trefawr Track, a forestry road north of Cwm-coed-Aeron Farm Llandovery, Wales, is the location of the Global Boundary Stratotype Section and Point (GSSP Llandovery ( Llanymddyfri) is a Market town in Carmarthenshire, Wales, lying on the River Tywi and the A40 road. A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon stratigraphic section which serves as the reference section for The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other The GSSP was ratified in 1984.

The boundary is defined as the first appearance of the graptolite Monograptus austerus sequens (the base of the Monograptus triangulatus biozone). First appearance datum is a term used by Geologists and paleontologists to designate the first (oldest appearance of a species in the geologic record Graptolites (Graptolithina are Fossil colonial Animals known chiefly from the Upper Cambrian through the Lower Carboniferous ( Mississippian The section is primarily mudstone, which yields an abundance of shelly faunas. Mudstone (also called mudrock) is a fine grained Sedimentary rock whose original constituents were Clays or Muds Grain size is up Fauna is all of the Animal life of any particular region or time The graptolite Diplograptus elongatus occurs immediately below the boundary.

References

See also

External links

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