The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also extends northwards into Greenland and Svalbard. These areas were a part of the ancient continent of Euramerica/Laurussia. In Britain it is a lithostratigraphic unit to which stratigraphers accord supergroup status and which is of considerable importance to early paleontology. For convenience the short version of the term, ORS is often used in literature on the subject. The term was coined to distinguish the sequence from the younger New Red Sandstone which also occurs widely throughout Britain.
The geology of Great Britain is renowned for its diversity. As a result of its eventful geological history, Great Britain shows a rich variety of landscapes across the constituent countries of England, Wales and Scotland. Rocks of almost all geological ages are represented at outcrop, from the Archaean onwards.
Ramsey Island is an island about 1 kilometre off St David's Head in Pembrokeshire on the northern side of St Brides Bay, in southwest Wales, in the community of St Davids and the Cathedral Close. It is 259 hectares in area. Ramsey means Hrafn's island.
Sir Andrew Crombie Ramsay was a Scottish geologist.
South Stack is an island situated just off Holy Island on the northwest coast of Anglesey, Wales.
John William Salter was an English naturalist, geologist, and palaeontologist.
The Borrowdale Volcanic Group is a group of igneous rock formations named after the Borrowdale area of the Lake District, in England. They are Caradocian in age. It is thought that they represent the remains of a volcanic island arc, approximately similar to the island arcs of the west Pacific today. This developed as oceanic crust to the (present) north-west and was forced by crustal movement under a continental land-mass to the present south-east. Such forcing under, as two plates meet, is termed subduction. This land-mass has been named Avalonia by geologists. It is now incorporated into England and Wales and a sliver of North America.
Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian Epoch of the Carboniferous Period. These rocks formed between 363 and 325 million years ago. Within England and Wales, the entire limestone succession, which includes subordinate mudstones and some thin sandstones, is known as the Carboniferous Limestone Supergroup.
Sir Aubrey Strahan KBE FRS was a British geologist. He was elected FRS in 1903. He was Director of the Geological Survey of Great Britain from 1914–1920. He won the Wollaston Medal of the Geological Society of London in 1919.
The geology of Wales is complex and varied; its study has been of considerable historical significance in the development of geology as a science. All geological periods from the Cryogenian to the Jurassic are represented at outcrop, whilst younger sedimentary rocks occur beneath the seas immediately off the Welsh coast. The effects of two mountain-building episodes have left their mark in the faulting and folding of much of the Palaeozoic rock sequence. Superficial deposits and landforms created during the present Quaternary period by water and ice are also plentiful and contribute to a remarkably diverse landscape of mountains, hills and coastal plains.
Henry Hicks (1837–1899) was a Welsh physician and geologist during the 19th century.
Joseph Beete Jukes, born to John and Sophia Jukes at Summer Hill, Birmingham, England, was a renowned geologist, author of several geological manuals and served as a naturalist on the expeditions of HMS Fly. Correspondents and friends addressed him as Beete Jukes.
Anglesey is an island off the north-west coast of Wales. It forms a principal area known as the Isle of Anglesey, that includes Holy Island across the narrow Cymyran Strait and some islets and skerries. Anglesey island, at 260 square miles (673 km2), is the largest in Wales, the seventh largest in Britain, largest in the Irish Sea and second most populous there after the Isle of Man. Isle of Anglesey County Council covers 276 square miles (715 km2), with a 2011 census population of 69,751, including 13,659 on Holy Island. The Menai Strait to the mainland is spanned by the Menai Suspension Bridge, designed by Thomas Telford in 1826, and the Britannia Bridge, built in 1850 and replaced in 1980. The largest town is Holyhead on Holy Island, whose ferry service with Ireland handles over two million passengers a year. The next largest is Llangefni, the county council seat. From 1974 to 1996 Anglesey was part of Gwynedd. Most full-time residents are habitual Welsh speakers. The Welsh name Ynys Môn is used for the UK Parliament and Senedd constituencies. The postcodes are LL58–LL78. It is also a historic county of Wales.
Jack Gordon Souther was an American-born Canadian geologist, volcanologist, professor and engineer. He contributed significantly to the early understanding of recent volcanic activity in the Canadian Cordillera. Many of his publications continue to be regarded as classics in their field, even now several decades after they were written.
The Cymru Terrane is one of five inferred fault bounded terranes that make up the basement rocks of the southern United Kingdom. The other notable geological terranes are the Charnwood Terrane, Fenland Terrane, Wrekin Terrane and the Monian Composite Terrane. In this article the definition of terrane is that implying rocks associated with the composition of the Precambrian basement. The Cymru Terrane is bounded to the northwest by the Menai Strait Fault System and to the southeast by the Pontesford Lineament. The geological terrane to the west is the Monian Composite Terrane and to the east is Wrekin Terrane. The majority of rocks in the area are associated with the outcrops that are evident at the faulted boundaries.
The Caerfai Group is a Cambrian lithostratigraphic group in west Wales. The name is derived from Caerfai Bay on the north coast of St Brides Bay on the Pembrokeshire coast where the strata are well exposed in coastal cliffs. This rock succession has previously been known variously as the Caerfai Series, Caerfai Formation and Caerfai Beds and largely ascribed to the British regional stratigraphic unit Comley Epoch, though these terms are now obsolete.
Catherine Alice Raisin was one of the most important early female geologists in Britain. Her research was primarily in the field of microscope petrology and mineralogy. She was the Head of the Geology department at Bedford College for Women, in London for 30 years, and strived for women's equality in education. Raisin was the first woman in Britain to lead a university geology department. She was also the Head of the Botany department at the Bedford College for Women.
The Holkerian is a sub-stage of the Viséan stage of the International Commission on Stratigraphy (ICS) geological timescale. It is one of five sub-stages commonly used in the Viséan stage within stratigraphy by British, Irish and other geologists outside the US and Asia.
The Holy Island Group is a sequence of metasedimentary rocks of Cambro-Ordovician age found in northern and western Anglesey and the adjacent Holy Island in North Wales. It comprises four formations; a lower South Stack Formation, an overlying Holyhead Formation, a succeeding Rhoscolyn Formation and an uppermost New Harbour Formation. The South Stack Formation outcrops on Holy Island, between Holyhead and South Stack and at Rhoscolyn, and also inland on Anglesey itself between Mynydd Mechell and Carreglefn. The Holyhead and Rhoscolyn formations are restricted to the Holyhead Mountain and Rhoscolyn areas of Holy Island. The New Harbour Formation, which previously enjoyed 'Group' status, is some 2km thick and conformably overlies the Rhoscolyn Formation. It extends across much of northern and western Anglesey and Holy Island.
The geology of Anglesey, the largest (714 km2) island in Wales is some of the most complex in the country. Anglesey has relatively low relief, the 'grain' of which runs northeast–southwest, i.e. ridge and valley features extend in that direction reflecting not only the trend of the late Precambrian and Palaeozoic age bedrock geology but also the direction in which glacial ice traversed and scoured the island during the last ice age. It was realised in the 1980s that the island is composed of multiple terranes, recognition of which is key to understanding its Precambrian and lower Palaeozoic evolution. The interpretation of the island's geological complexity has been debated amongst geologists for decades and recent research continues in that vein.
Wales 
