The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...

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 Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is ...

and Svalbard. These areas were a part of the ancient

continent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...

of Euramerica/Laurussia. In Britain it is a

lithostratigraphic Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are primarily igneous ...

unit (a sequence of

rock strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as e ...

) to which stratigraphers accord supergroup status and which is of considerable importance to early

paleontology Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fos ...

. 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.

Sedimentology

The Old Red Sandstone describes a suite of

sedimentary 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 ...

rocks deposited in a variety of environments during the

but extending back into the late

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago (Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoi ...

and on into the earliest part of the Carboniferous. The body of rock, or

facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formatio ...

, is dominated by

alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Al ...

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...

s and conglomerates at its base, and progresses to a combination of

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, fl ...

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much lar ...

s and

river A river is a natural flowing watercourse, usually freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the ...

sediments. The familiar red colour of these rocks arises from the presence of

iron oxide Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are non-stoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of w ...

but not all the Old Red Sandstone is red or sandstone — the sequence also includes conglomerates, mudstones, siltstones and thin

limestones Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when t ...

and colours can range from grey and green through to red and purple. These deposits are closely associated with the erosion of the Caledonian Mountain chain which was thrown up by the collision of the former continents of

Avalonia Avalonia was a microcontinent in the Paleozoic era. Crustal fragments of this former microcontinent underlie south-west Great Britain, southern Ireland, and the eastern coast of North America. It is the source of many of the older rocks of We ...

, Baltica and

Laurentia Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, althoug ...

to form the Old Red Sandstone Continent- an event known as 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 ...

. Many fossils are found within the rocks, including early fishes, arthropods and plants. As is typical with terrestrial red beds, the vast majority of the rock is unfossiliferous; however there are isolated, localized beds within the rock that do contain fossils. Rocks of this age were also laid down in

South West England South West England, or the South West of England, is one of nine official regions of England. It consists of the counties of Bristol, Cornwall (including the Isles of Scilly), Dorset, Devon, Gloucestershire, Somerset and Wiltshire. Cities and ...

(hence the name 'Devonian'; from

Devon Devon ( , historically known as Devonshire , ) is a ceremonial and non-metropolitan county in South West England. The most populous settlement in Devon is the city of Plymouth, followed by Devon's county town, the city of Exeter. Devon is ...

) though these are of true marine origin and are not included within the Old Red Sandstone.

Stratigraphy

Since the Old Red Sandstone consists predominantly of rocks of

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

origin, it does not generally contain marine

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s which would otherwise prove useful in correlating one occurrence of the rock with another, both between and within individual

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subsidence ...

s. Accordingly, local stage names were devised and these remain in use to some extent today though there is an increasing use of international stage names. Thus in the Anglo-Welsh Basin, there are frequent references to the Downtonian, Dittonian, Breconian and Farlovian stages in the literature. The existence of a number of distinct sedimentary basins throughout Britain has been established.

Orcadian Basin

The Orcadian Basin extends over a wide area of North East Scotland and the neighbouring seas. It encompasses the Moray Firth and adjoining land areas, Caithness, Orkney and parts of

Shetland Shetland, also called the Shetland Islands and formerly Zetland, is a subarctic archipelago in Scotland lying between Orkney, the Faroe Islands and Norway. It is the northernmost region of the United Kingdom. The islands lie about to the ...

. South of the Moray Firth, two distinct sub-basins are recognised at Turriff and at Rhynie. The sequence is more than thick in parts of Shetland. The main basin is considered to be an intramontane basin resulting from crustal rifting associated with post-Caledonian extension, possibly accompanied by strike-slip faulting along the Great Glen Fault system.

Argyll

There are a scatter of exposures of the Old Red Sandstone around

Oban Oban ( ; ' in Scottish Gaelic meaning ''The Little Bay'') is a resort town within the Argyll and Bute council area of Scotland. Despite its small size, it is the largest town between Helensburgh and Fort William. During the tourist season, t ...

and the Isle of Kerrera on the West Highland coast, this unit is sometimes referred to as the Kerrera Sandstone Formation. The unit is up to 128m thick in its type area and consists of green and red sandstones and conglomerates, typically containing large ( across) elliptical well rounded clasts, accompanied by siltstones, mudstones and limestones. On Kerrera a conglomerate of

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

boulders rests unconformably on Dalradian black, pyritic

slate Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic ro ...

s (

Easdale Easdale ( gd, Eilean Èisdeal) is one of the Slate Islands, in the Firth of Lorn, Scotland. Once the centre of the Scottish slate industry, there has been some recent island regeneration by the owners. This is the smallest of the Inner Hebrides ...

Slate) of the

Easdale Subgroup Easdale ( gd, Eilean Èisdeal) is one of the Slate Islands, in the Firth of Lorn, Scotland. Once the centre of the Scottish slate industry, there has been some recent island regeneration by the owners. This is the smallest of the Inner Hebrides ...

. On Oban there is merely an erosional contact incorporating debris of the slate in a basal conglomerate. The ORS around Oban are considered latest

(

Pridoli Pridoli ''(Přídolí)'' may refer to: * Pridoli epoch, part of the Silurian period *Přídolí Přídolí (german: Priethal) is a market town in Český Krumlov District in the South Bohemian Region of the Czech Republic. It has about 700 inhab ...

) to earliest Devonian in age. They are interpreted as

alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...

s which filled a depositional basin from the east and northeast. Small

outliers In statistics, an outlier is a data point that differs significantly from other observations. An outlier may be due to a variability in the measurement, an indication of novel data, or it may be the result of experimental error; the latter a ...

occur near Taynuilt and either side of Loch Avich. The deposits are especially obvious on Kerrera where they form the bedrock across half of the island. These are conformably overlain by peperite and the

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 ...

ic and andesitic Lorne plateau lavas. The ORS on Kerrera and isolated localities around Oban are known for their fossils, particularly fish. Gardenstown Old Red Sandstone - geograph

Gardenstown Old Red Sandstone - geograph

Midland Valley of Scotland

The Midland Valley

graben In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic contex ...

defined by the Highland Boundary Fault in the north and the Southern Uplands Fault in the south harbours not only a considerable amount of Old Red Sandstone sedimentary rocks but also igneous rocks of this age associated with extensive

volcanism Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the Earth#Surface, surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the su ...

. There is a continuous outcrop along the Highland Boundary Fault from

Stonehaven Stonehaven ( , ) is a town in Scotland. It lies on Scotland's northeast coast and had a population of 11,602 at the 2011 Census. After the demise of the town of Kincardine, which was gradually abandoned after the destruction of its royal cast ...

on the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

coast to

Helensburgh Helensburgh (; gd, Baile Eilidh) is an affluent coastal town on the north side of the Firth of Clyde in Scotland, situated at the mouth of the Gareloch. Historically in Dunbartonshire, it became part of Argyll and Bute following local govern ...

and beyond to Arran. A more disconnected series of outcrops occur along the line of the Southern Uplands Fault from

Edinburgh Edinburgh ( ; gd, Dùn Èideann ) is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. Historically part of the county of Midlothian (interchangeably Edinburghshire before 1921), it is located in Lothian ...

Girvan Girvan ( gd, Inbhir Gharbhain, "mouth of the River Girvan") is a burgh and harbour town in Carrick, South Ayrshire, Scotland. Girvan is situated on the east coast of the Firth of Clyde, with a population of about 6,450. It lies south of Ayr, ...

. Old Red Sandstone often occurs in conjunction with conglomerate formations, one such noteworthy

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 ...

side exposure being the

Fowlsheugh Nature Reserve Fowlsheugh is a coastal nature reserve in Kincardineshire, northeast Scotland, known for its cliff formations and habitat supporting prolific seabird nesting colonies. Designated as a Site of Special Scientific Interest (SSSI) by Scottish Natura ...

, Kincardineshire.

Scottish borders

A series of outcrops occur from

East Lothian East Lothian (; sco, East Lowden; gd, Lodainn an Ear) is one of the 32 council areas of Scotland, as well as a historic county, registration county and lieutenancy area. The county was called Haddingtonshire until 1921. In 1975, the hi ...

southwards through

Berwickshire Berwickshire ( gd, Siorrachd Bhearaig) is a historic county, registration county and lieutenancy area in south-eastern Scotland, on the English border. Berwickshire County Council existed from 1890 until 1975, when the area became part of ...

. Hutton's famous unconformity at Siccar Point occurs within this basin - see History of study below.

Anglo-Welsh Basin

This relatively large basin extends across much of South Wales from southern Pembrokeshire in the west through

Carmarthenshire Carmarthenshire ( cy, Sir Gaerfyrddin; or informally ') is a county in the south-west of Wales. The three largest towns are Llanelli, Carmarthen and Ammanford. Carmarthen is the county town and administrative centre. The county is known ...

into

Powys Powys (; ) is a Local government in Wales#Principal areas, county and Preserved counties of Wales, preserved county in Wales. It is named after the Kingdom of Powys which was a Welsh succession of states, successor state, petty kingdom and princi ...

and Monmouthshire and through the southern

Welsh Marches The Welsh Marches ( cy, Y Mers) is an imprecisely defined area along the border between England and Wales in the United Kingdom. The precise meaning of the term has varied at different periods. The English term Welsh March (in Medieval Latin ...

, notably into

Herefordshire Herefordshire () is a county in the West Midlands of England, governed by Herefordshire Council. It is bordered by Shropshire to the north, Worcestershire to the east, Gloucestershire to the south-east, and the Welsh counties of Monmouthshire ...

Worcestershire Worcestershire ( , ; written abbreviation: Worcs) is a county in the West Midlands of England. The area that is now Worcestershire was absorbed into the unified Kingdom of England in 927, at which time it was constituted as a county (see H ...

and

Gloucestershire Gloucestershire ( abbreviated Glos) is a county in South West England. The county comprises part of the Cotswold Hills, part of the flat fertile valley of the River Severn and the entire Forest of Dean. The county town is the city of Gl ...

. Outliers in

Somerset ( en, All The People of Somerset) , locator_map = , coordinates = , region = South West England , established_date = Ancient , established_by = , preceded_by = , origin = , lord_lieutenant_office =Lord Lieutenant of Somerset , lor ...

and north

complete the extent of this basin. With the exception of south Pembrokeshire, all parts of the basin are represented by a range of lithologies assigned to the Lower Devonian and to the Upper Devonian, the contact between the two being unconformable and representing the complete omission of any Middle Devonian sequence. The lowermost formations are of upper Silurian age, these being the Downton Castle Sandstone Formation and the overlying Raglan Mudstone Formation except in Pembrokeshire where a more complex series of formations is recognised. In the east of the basin, the top of the Raglan Mudstone is marked by a well-developed calcrete, the

Bishop's Frome Limestone The Bishop's Frome Limestone (or Bishops Frome Limestone) is a rock unit within the Raglan Mudstone Formation of the Old Red Sandstone occurring in the border region between England and South Wales. This limestone is a calcrete, that is to say it ...

. The lowermost Devonian formation is the St Maughans Formation, itself overlain by the Brownstones Formation though with an intervening Senni Formation over much of the area. The Upper Devonian sequence is rather thinner and comprises a series of formations which are more laterally restricted. In the

Brecon Beacons The Brecon Beacons ( cy, Bannau Brycheiniog, ) are a mountain range in South Wales. In a narrow sense, the name refers to the range of Old Red Sandstone peaks which lie to the south of Brecon. Sometimes referred to as "the central Beacons" t ...

, the Plateau Beds Formation is unconformably overlain by the Grey Grits Formation though further east these divisions are replaced by the Quartz Conglomerate Group which is itself subdivided into a variety of different formations. Yensaby castle 1

Pembrokeshire

The sequence in Pembrokeshire differs from that of the main part of the basin and falls into two parts. In North Pembrokeshire to the north of the Ritec Fault, both the middle and upper ORS are missing with only the lower ORS present; this is divided into an earlier

Milford Haven Group The Milford Haven Group is a late Silurian to early Devonian lithostratigraphy, lithostratigraphic group (stratigraphy), group (a sequence of rock strata) in west Wales. The name is derived from the estuary and town of Milford Haven in south Pemb ...

comprising in ascending order, the Red Cliff, Sandy Haven and Gelliswick Bay formations and a later

Cosheston Group The Cosheston Group is an early Devonian lithostratigraphic group (a sequence of rock strata) in west Wales. The name is derived from the village of Cosheston in south Pembrokeshire. The Group comprises (in ascending order) the Llanstadwell, B ...

with, again in ascending order, its constituent Llanstadwell, Burton Cliff, Mill Bay, Lawrenny Cliff and New Shipping formations. These respectively equate with the Temeside, Raglan Mudstone and St Maughans formations of the central and eastern part of the basin. *''- middle and upper ORS missing -'' *

New Shipping Formation New is an adjective referring to something recently made, discovered, or created. New or NEW may refer to: Music * New, singer of K-pop group The Boyz Albums and EPs * ''New'' (album), by Paul McCartney, 2013 * ''New'' (EP), by Regurgitator, ...

Lawrenny Cliff Formation Lawrenny is a village and parish in the community and electoral ward of Martletwy in the county of Pembrokeshire, Wales. It is on a peninsula of the River Cleddau estuary upriver from Milford Haven where it branches off towards the Cresswell ...

Mill Bay Formation Mill may refer to: Science and technology * * Mill (grinding) * Milling (machining) * Millwork * Textile mill * Steel mill, a factory for the manufacture of steel * List of types of mill * Mill, the arithmetic unit of the Analytical Engine ea ...

Burton Cliff Formation Burton, Burtons, or Burton's may refer to: Companies * Burton (retailer), a clothing retailer **Burton's, Abergavenny, a shop built for the company in 1937 **The Montague Burton Building, Dublin a shop built for the company between 1929 an ...

Llanstadwell Formation Llanstadwell ( cy, Llanudwal) is a small village, parish and community in south Pembrokeshire, Wales, on the north bank of the River Cleddau between Milford Haven and Neyland. The community of Llanstadwell includes the settlements of Hazelbeac ...

** Gelliswick Bay Formation **

Sandy Haven Formation Sandy may refer to: People and fictional characters * Sandy (given name), including a list of people and fictional characters * Sandy (surname), a list of people * Sandy (singer), Brazilian singer and actress Sandy Leah Lima (born 1983) *(Sandy) ...

(inc. Townsend Tuff Beds) **

Albion Sands Formation Albion is an alternative name for Great Britain. The oldest attestation of the toponym comes from the Greek language. It is sometimes used poetically and generally to refer to the island, but is less common than 'Britain' today. The name for Scot ...

/ Lindsway Bay Formation **

Red Cliff Formation Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...

In south Pembrokeshire to the south of the Ritec Fault, the lower ORS is represented by, in ascending order, the Freshwater East, Moors Cliff and Freshwater West formations. These are unconformably overlain by the Ridgeway Conglomerate Formation. The middle ORS is missing whilst the Upper ORS is represented by the Gupton and West Angle formations. * Skrinkle Sandstone Group ** West Angle Formation **

Gupton Formation Gupton is an unincorporated community in Franklin County, North Carolina, Franklin County, North Carolina, United States. Gupton is located approximately eight miles east-northeast of Ingleside, North Carolina, Ingleside, off North Carolina Highw ...

* ''- part of middle ORS missing -'' *

Ridgeway Conglomerate Formation A ridgeway (road) is a road or path that follows a ridge, or the highest part of the landscape. Roads and pathways *The Ridgeway, an ancient track in southern England, which now forms part of the Ridgeway Path or National Trail *Ridgeway (London), ...

* ''- part of middle ORS missing -'' *

Freshwater West Formation Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does i ...

(inc. Rat Island Mudstone Member and Conigar Pit Sandstone Member) **

Moor Cliffs Formation Moor or Moors may refer to: Nature and ecology * Moorland, a habitat characterized by low-growing vegetation and acidic soils. Ethnic and religious groups * Moors, Muslim inhabitants of the Maghreb, Iberian Peninsula, Sicily, and Malta during ...

(inc. Chapel point calcretes member and Townsend Tuff Bed) ** Freshwater East Formation The Freshwater East Formation, and corresponding Red Cliff Formation of north Pembrokeshire, are both late Silurian in age.

Anglesey

A small and separate basin exists here where both

and

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

deposits are recorded. Both the middle and upper ORS are missing but the lower ORS is represented, in ascending order, by the Bodafon, Traeth Bach, Porth y Mor and Traeth Lligwy formations. Calcretes are also recorded representing carbonate-rich soils developed between periods of sediment deposition. The present day outcrop occupies a narrow zone from Dulas Bay on Anglesey's northeast coast, southwards to the town of Llangefni.

History of study

In 1787

James Hutton James Hutton (; 3 June O.S.172614 June 1726 New Style. – 26 March 1797) was a Scottish geologist, agriculturalist, chemical manufacturer, naturalist and physician. Often referred to as the father of modern geology, he played a key role ...

noted what is now known as Hutton's Unconformity at Inchbonny,

Jedburgh Jedburgh (; gd, Deadard; sco, Jeddart or ) is a town and former royal burgh in the Scottish Borders and the traditional county town of the historic county of Roxburghshire, the name of which was randomly chosen for Operation Jedburgh in s ...

, and in early 1788 he set off with

John Playfair John Playfair FRSE, FRS (10 March 1748 – 20 July 1819) was a Church of Scotland minister, remembered as a scientist and mathematician, and a professor of natural philosophy at the University of Edinburgh. He is best known for his book ''Illu ...

to the

coast and found more examples of this sequence in the valleys of the Tower and Pease Burns near Cockburnspath. They then took a boat trip from Dunglass Burn east along the coast with the geologist Sir James Hall of

Dunglass Dunglass is a hamlet in East Lothian, Scotland, lying east of the Lammermuir Hills on the North Sea coast, within the parish of Oldhamstocks. It has a 15th-century collegiate church, now in the care of Historic Scotland. Dunglass is the birthpl ...

and at Siccar Point found what Hutton called "a beautiful picture of this junction washed bare by the sea", where 345-million-year-old Old Red Sandstone overlies 425-million-year-old

greywacke Greywacke or graywacke ( German ''grauwacke'', signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or li ...

. In the early 19th century, the paleontology of the formation was studied intensively by Hugh Miller, Henry Thomas De la Beche,

Roderick Murchison Sir Roderick Impey Murchison, 1st Baronet, (19 February 1792 – 22 October 1871) was a Scottish geologist who served as director-general of the British Geological Survey from 1855 until his death in 1871. He is noted for investigating and d ...

, and

Adam Sedgwick Adam Sedgwick (; 22 March 1785 – 27 January 1873) was a British geologist and Anglican priest, one of the founders of modern geology. He proposed the Cambrian and Devonian period of the geological timescale. Based on work which he did on ...

—Sedgwick's interpretation was the one that placed it in the

: he coined the name of that period. The term 'Old Red Sandstone' was originally used in 1821 by Scottish naturalist and mineralogist Robert Jameson to refer to the red rocks which underlay the 'Mountain Limestone' i.e. the Carboniferous Limestone. They were thought at that time to be the British version of Germany's

Rotliegendes The Rotliegend, Rotliegend Group or Rotliegendes (german: the underlying red) is a lithostratigraphic unit (a sequence of rock strata) of latest Carboniferous to Guadalupian (middle Permian) age that is found in the subsurface of large areas in ...

, which is in fact of

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Pale ...

age. Many of the

science Science is a systematic endeavor that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earli ...

stratigraphy Stratigraphy is a branch of geology concerned with the study of rock layers ( strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithost ...

's early debates were about the Old Red Sandstone. In older geological works predating theories of

plate tectonics Plate tectonics (from the la, label= Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large t ...

, the United States' Catskill Delta formation is sometimes referred to as part of the Old Red Sandstone. In the modern day it is recognized that the two are not stratigraphically continuous but are very similar due to being formed at approximately the same time by the same processes.

Use as a building stone

The Old Red Sandstone has been widely used as a building stone across those regions where it outcrops. Notable examples of its use can be found in the area surrounding

Stirling Stirling (; sco, Stirlin; gd, Sruighlea ) is a city in central Scotland, northeast of Glasgow and north-west of Edinburgh. The market town, surrounded by rich farmland, grew up connecting the royal citadel, the medieval old town with its me ...

Perth Perth is the list of Australian capital cities, capital and largest city of the Australian states and territories of Australia, state of Western Australia. It is the list of cities in Australia by population, fourth most populous city in Aust ...

and Tayside. The inhabitants of

Caithness Caithness ( gd, Gallaibh ; sco, Caitnes; non, Katanes) is a historic county, registration county and lieutenancy area of Scotland. Caithness has a land boundary with the historic county of Sutherland to the west and is otherwise bounded b ...

at the northeastern tip of Scotland also used the stone to a considerable extent. Old Red Sandstone has also frequently been used in buildings in

, Monmouthshire and the former Brecknockshire (now south

) of south Wales.

Notable buildings

;Canada *

New York Life Insurance Building, Montreal Montreal's New York Life Insurance Building (also known as the Quebec Bank Building) is an office building at Place d'Armes in what is now known as Old Montreal, erected in 1887-1889. At the time of its completion, it was the tallest commercial ...

;England *

Goodrich Castle Goodrich Castle is a Norman medieval castle ruin north of the village of Goodrich in Herefordshire, England, controlling a key location between Monmouth and Ross-on-Wye. It was praised by William Wordsworth as the "noblest ruin in Hereford ...

Ross-on-Wye Ross-on-Wye (Welsh: ''Rhosan ar Wy'') is a market town in England, near the border with Wales. It had a population of 10,582 according to the 2011 census, estimated at 11,309 in 2019. It lies in south-eastern Herefordshire, on the River Wye and ...

market hall,

* Shrewsbury Castle,

Shropshire Shropshire (; alternatively Salop; abbreviated in print only as Shrops; demonym Salopian ) is a landlocked historic county in the West Midlands region of England. It is bordered by Wales to the west and the English counties of Cheshire to ...

* Hereford Cathedral,

;Scotland * Arbroath Abbey,

Angus Angus may refer to: Media * ''Angus'' (film), a 1995 film * ''Angus Og'' (comics), in the ''Daily Record'' Places Australia * Angus, New South Wales Canada * Angus, Ontario, a community in Essa, Ontario * East Angus, Quebec Scotland * Angu ...

* Muchalls Castle,

Aberdeenshire Aberdeenshire ( sco, Aiberdeenshire; gd, Siorrachd Obar Dheathain) is one of the 32 council areas of Scotland. It takes its name from the County of Aberdeen which has substantially different boundaries. The Aberdeenshire Council area incl ...

* St Magnus Cathedral,

Orkney Orkney (; sco, Orkney; on, Orkneyjar; nrn, Orknøjar), also known as the Orkney Islands, is an archipelago in the Northern Isles of Scotland, situated off the north coast of the island of Great Britain. Orkney is 10 miles (16 km) nort ...

* Stonehaven Tolbooth,

;Wales * Raglan Castle, Monmouthshire *

Tintern Abbey Tintern Abbey ( cy, Abaty Tyndyrn ) was founded on 9 May 1131 by Walter de Clare, Lord of Chepstow. It is situated adjacent to the village of Tintern in Monmouthshire, on the Welsh bank of the River Wye, which at this location forms the bo ...

, Monmouthshirehttp://www.museumwales.ac.uk/media/4/9/5/2/Newsletter_5.pdf * Brecon Cathedral,

References

External links

{{commons category, Old Red Sandstone
Cawdor Castle — built from Old Red Sandstone
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