The coal measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System. The Coal Measures Group consists of the Upper Coal Measures Formation, the Middle Coal Measures Formation and the Lower Coal Measures Formation; the group records the deposition of fluvio-deltaic sediments which consists of clastic rocks interstratified with the beds of coal. In most places, the coal measures are underlain by coarser clastic sequences known as Millstone Grit, of Namurian age; the top of the coal measures may be marked by an unconformity, the overlying rocks being Permian or in age. In some parts of Britain, the Coal Measures grade up into coal-barren red beds of late Westphalian and Stephanian age. Within the Pennine Basin these barren measures are now referred to as the Warwickshire Group, from the district where they achieve their thickest development; the coal measures formed during Westphalian and earliest Stephanian times in the European chronostratigraphical scheme.
In the eastern United States the term coal measures has been applied to the Pennsylvanian coal fields. The Pittsburgh coal seam is considered the base of the upper coal measures, exposed along the Monongahela River, while the lower coal measures are exposed along the Allegheny River; the term coal measures has historically been used in other parts of the world for coal-bearing successions of various ages, e.g. the Permian coal measures of Australia and the late Cretaceous and early Tertiary coal measures found in New Zealand. However, these usages are informal. Coal mining CJ Cleal and BA Thomas, Plants of the British Coal Measures, The Palaeontological Association, 1994. CJ Cleal and BA Thomas, British Upper Carboniferous stratigraphy, Chapman & Hall, London, 1995
Craig y Llyn
For the subsidiary summit of Cadair Idris see Craig-y-llyn. Craig y Llyn is a mountain situated to the south of the village of Rhigos on the south side of the upper Vale of Neath and north of the Rhondda Valleys in South Wales; the summit of Craig y Llyn lies within the borough of Neath Port Talbot whilst its eastern slopes are within Rhondda Cynon Taf, the boundary running in a north - south direction 200 m to the east of the summit. The name derives from the sandstone cliffs which drop steeply down to the two lakes on its northern side. Ground on this side has been designated as a Site of Special Scientific Interest; the hill is covered by forestry, except for the steep north and northeast faces, is crowned with a trig point. Several footpaths cross near the summit including the Coed Morgannwg Way; the highest point in Rhondda Cynon Taf, Craig y Llyn, is known as the Rhigos Mountain after the village of Rhigos located on the northern side of the mountain in the Cynon Valley. The Countryside Council for Wales states that the site has been categorised as a Site of Special Interest because it supports "...two special habitat features, is of special interest for a plant, the water lobelia.
The first habitat feature is standing water, supporting aquatic plants typical of lakes with low nutrient content. Some of these plants are not known from anywhere further south in the UK; the second is dry heath, found on the slopes above the lakes. The hill is composed of a thick sequence of sandstones and mudstones assigned to the South Wales Coal Measures; the summit plateau is formed from the Pennant Sandstone of the Upper Coal Measures. The two cwms on its northern flanks which shelter Llyn Llyn Fawr are of glacial origin. A landslipped mass of rock lies above the western end of the latter lake. List of Sites of Special Scientific Interest in Mid & South Glamorgan www.geograph.co.uk: photos of Craig y Llyn and surrounding area
The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago, to the beginning of the Permian Period, 298.9 Mya. The name Carboniferous means "coal-bearing" and derives from the Latin words carbō and ferō, was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the modern'system' names to be employed, reflects the fact that many coal beds were formed globally during that time; the Carboniferous is treated in North America as two geological periods, the earlier Mississippian and the Pennsylvanian. Terrestrial animal life was well established by the Carboniferous period. Amphibians were the dominant land vertebrates, of which one branch would evolve into amniotes, the first terrestrial vertebrates. Arthropods were very common, many were much larger than those of today. Vast swaths of forest covered the land, which would be laid down and become the coal beds characteristic of the Carboniferous stratigraphy evident today.
The atmospheric content of oxygen reached its highest levels in geological history during the period, 35% compared with 21% today, allowing terrestrial invertebrates to evolve to great size. The half of the period experienced glaciations, low sea level, mountain building as the continents collided to form Pangaea. A minor marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred at the end of the period, caused by climate change. In the United States the Carboniferous is broken into Mississippian and Pennsylvanian subperiods; the Mississippian is about twice as long as the Pennsylvanian, but due to the large thickness of coal-bearing deposits with Pennsylvanian ages in Europe and North America, the two subperiods were long thought to have been more or less equal in duration. In Europe the Lower Carboniferous sub-system is known as the Dinantian, comprising the Tournaisian and Visean Series, dated at 362.5-332.9 Ma, the Upper Carboniferous sub-system is known as the Silesian, comprising the Namurian and Stephanian Series, dated at 332.9-298.9 Ma.
The Silesian is contemporaneous with the late Mississippian Serpukhovian plus the Pennsylvanian. In Britain the Dinantian is traditionally known as the Carboniferous Limestone, the Namurian as the Millstone Grit, the Westphalian as the Coal Measures and Pennant Sandstone; the International Commission on Stratigraphy faunal stages from youngest to oldest, together with some of their regional subdivisions, are: A global drop in sea level at the end of the Devonian reversed early in the Carboniferous. There was a drop in south polar temperatures; these conditions had little effect in the deep tropics, where lush swamps to become coal, flourished to within 30 degrees of the northernmost glaciers. Mid-Carboniferous, a drop in sea level precipitated a major marine extinction, one that hit crinoids and ammonites hard; this sea level drop and the associated unconformity in North America separate the Mississippian subperiod from the Pennsylvanian subperiod. This happened about 323 million years ago, at the onset of the Permo-Carboniferous Glaciation.
The Carboniferous was a time of active mountain-building as the supercontinent Pangaea came together. The southern continents remained tied together in the supercontinent Gondwana, which collided with North America–Europe along the present line of eastern North America; this continental collision resulted in the Hercynian orogeny in Europe, the Alleghenian orogeny in North America. In the same time frame, much of present eastern Eurasian plate welded itself to Europe along the line of the Ural Mountains. Most of the Mesozoic supercontinent of Pangea was now assembled, although North China, South China continents were still separated from Laurasia; the Late Carboniferous Pangaea was shaped like an "O." There were two major oceans in the Carboniferous—Panthalassa and Paleo-Tethys, inside the "O" in the Carboniferous Pangaea. Other minor oceans were shrinking and closed - Rheic Ocean, the small, shallow Ural Ocean and Proto-Tethys Ocean. Average global temperatures in the Early Carboniferous Period were high: 20 °C.
However, cooling during the Middle Carboniferous reduced average global temperatures to about 12 °C. Lack of growth rings of fossilized trees suggest a lack of seasons of a tropical climate. Glaciations in Gondwana, triggered by Gondwana's southward movement, continued into the Permian and because of the lack of clear markers and breaks, the deposits of this glacial period are referred to as Permo-Carboniferous in age; the cooling and drying of the climate led to the Carboniferous Rainforest Collapse during the late Carboniferous. Tropical rainforests fragmented and were devastated by climate change. Carboniferous rocks in Europe and eastern North America consist of a repeated sequence of limestone, sandstone and coal beds. In North America, the early Carboniferous is marine
English Heritage is a charity that manages over 400 historic monuments and places. These include medieval castles, Roman forts and country houses; the charity states that it uses these properties to ‘bring the story of England to life for over 10 million people each year’. Within its portfolio are Stonehenge, Dover Castle, Tintagel Castle and the best preserved parts of Hadrian's Wall. English Heritage manages the London Blue Plaque scheme, which links influential historical figures to particular buildings; when formed in 1983, English Heritage was the operating name of an executive non-departmental public body of the British Government titled the Historic Buildings and Monuments Commission for England, that ran the national system of heritage protection and managed a range of historic properties. It was created to combine the roles of existing bodies that had emerged from a long period of state involvement in heritage protection. In 1999 the organisation merged with the Royal Commission on the Historical Monuments of England and the National Monuments Record, bringing together resources for the identification and survey of England's historic environment.
On 1 April 2015, English Heritage was divided into two parts: Historic England, which inherited the statutory and protection functions of the old organisation, the new English Heritage Trust, a charity that would operate the historic properties, which took on the English Heritage operating name and logo. The British government gave the new charity an £80 million grant to help establish it as an independent trust, although the historic properties remained in the ownership of the state. Over the centuries, what is now called'Heritage' has been the responsibility of a series of state departments. There was the'Kings Works' after the Norman Conquest. Responsibility subsequently transferred to the Ministry of Public Building and Works to the Department of the Environment and now the Department for Culture and Sport; the state's legal responsibility for the historic environment goes back to the Ancient Monuments Protection Act 1882. Central government subsequently developed several systems of heritage protection for different types of'assets', introducing listing for buildings after WW2 and conservation areas in the 1960s.
In 1983 Secretary of State for the Environment Michael Heseltine gave national responsibility for the historic environment to a semi‑autonomous agency to operate under ministerial guidelines and to government policy. The Historic Buildings and Monuments Commission was formed under the terms of the National Heritage Act 1983 on 1 April 1984; the 1983 Act dissolved the bodies that had provided independent advice – the Ancient Monuments Board for England and the Historic Buildings Council for England and incorporated these functions in the new body. Soon after, the commission gained the operating name of English Heritage by its first Chairman, Lord Montagu of Beaulieu. A national register of historic parks and gardens, was set up in 1984, a register for historic battlefields was created in March 1995.'Registration' is a material consideration in the planning process. In April 1999 English Heritage merged with the Royal Commission on the Historical Monuments of England and the National Monuments Record, bringing together resources for the identification and survey of England's historic environment.
By adoption this included responsibility for the national record of archaeological sites from the Ordnance Survey. These, together with other nationally important external acquisitions, meant that English Heritage was one of the largest publicly accessible archives in the UK: 2.53 million records are available online, including more than 426,000 images. In 2010–2011 it recorded 4.3 million unique online user sessions and over 110,000 people visited NMR exhibitions held around the country in 2009/10. In 2012 the section responsible for archive collections was renamed the English Heritage Archive; as a result of the National Heritage Act 2002, English Heritage acquired administrative responsibility for historic wrecks and submerged landscapes within 12 miles of the English coast. The administration of the listed building system was transferred from DCMS to English Heritage in 2006. However, actual listing decisions still remained the responsibility of the Secretary of State for Culture and Sport, required by the Planning Act 1990 to approve a list of buildings of special architectural or historic interest.
Following the Public Bodies Reform in 2010, English Heritage was confirmed as the government's statutory adviser on the historic environment, the largest source of non-lottery grant funding for heritage assets. It was retained on grounds of "performing a technical function which should remain independent from Government"; however the department suffered from budget cuts during the recession of the 2010s resulting in a repairs deficit of £100 million. In June 2013 the British Government announced plans to provide an £80 million grant to enable English Heritage to become a self-financing charity; the national portfolio of historic properties remain in public ownership, but the new English Heritage will be licensed to manage them. The change occu
A stratigraphic unit is a volume of rock of identifiable origin and relative age range, defined by the distinctive and dominant mapped and recognizable petrographic, lithologic or paleontologic features that characterize it. Units must be mappable and distinct from one another, but the contact need not be distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Sequences of sedimentary and volcanic rocks are subdivided on the basis of their lithology. Going from smaller to larger in scale, the main units recognised are Bed, Formation and Supergroup. A bed is a lithologically distinct layer within a member or formation and is the smallest recognisable stratigraphic unit; these are not named, but may be in the case of a marker horizon. A member is a named lithologically distinct part of a formation. Not all formations are subdivided in this way and where they are recognized, they may only form part of the formation. Formations are the primary units used in the subdivision of a sequence and may vary in scale from tens of centimetres to kilometres.
They should be distinct lithologically from other formations, although the boundaries do not need to be sharp. To be formally recognised, a formation must have sufficient extent to be useful in mapping an area. A group is more formations that share certain lithological characteristics. A group may be made up of different formations in different geographical areas and individual formations may appear in more than one group. A supergroup is a set of two or more associated groups and/or formations that share certain lithological characteristics. A supergroup may be made up of different groups in different geographical areas. A sequence of fossil-bearing sedimentary rocks can be subdivided on the basis of the occurrence of particular fossil taxa. A unit defined in this way is known as a biostratigraphic unit shortened to biozone; the five used types of biozone are assemblage, abundance and lineage zones. An assemblage zone is a stratigraphic interval characterised by an assemblage of three or more coexisting fossil taxa that distinguish it from surrounding strata.
A range zone is a stratigraphic interval that represents the occurrence range of a specific fossil taxon, based on the localities where it has been recognised. An abundance zone is a stratigraphic interval in which the abundance of a particular taxon is greater than seen in neighbouring parts of the succession. An interval zone is a stratigraphic interval whose top and base are defined by horizons that mark the first or last occurrence of two different taxa. A lineage zone is a stratigraphic interval that contains fossils that represent parts of the evolutionary lineage of a particular fossil group; this is a special case of a range zone. Chronostratigraphy Glaciology Magnetostratigraphy Sedimentology Sequence stratigraphy Stratigraphy International Commission on Stratigraphy Stratigraphic Guide
Bath Stone is an oolitic limestone comprising granular fragments of calcium carbonate. Obtained from the Combe Down and Bathampton Down Mines under Combe Down, England, its warm, honey colouring gives the World Heritage City of Bath, its distinctive appearance. An important feature of Bath Stone is that it is a'freestone', so-called because it can be sawn or'squared up' in any direction, unlike other rocks such as slate, which forms distinct layers. Bath Stone has been used extensively as a building material throughout southern England, for churches and public buildings such as railway stations; some quarries are still in use, but the majority have been converted to other purposes or are being filled in. Bath Stone is an oolitic limestone comprising granular fragments of calcium carbonate laid down during the Jurassic Period when the region, now Bath was under a shallow sea. Layers of marine sediment were deposited, individual spherical grains were coated with lime as they rolled around the sea bed, forming the Bathonian Series of rocks.
Under the microscope, these grains or ooliths are sedimentary rock formed from ooids: spherical grains composed of concentric layers. That name derives from the Hellenic word òoion for egg. Oolites consist of ooids of diameter 0.25–2 mm. Rocks composed of ooids larger than 2 mm are called pisolites, they contain minute fragments of shell or rock, sometimes decayed skeletons of marine life. Bath stone was taken from the Bath Oolite Member and the Combe Down Member of the Chalfield Oolite Formation, part of the Great Oolite Group. An important feature of Bath Stone is that it is a freestone, one that can be sawn or'squared up' in any direction, unlike other rocks such as slate, which forms distinct layers. In the Roman and Medieval periods, Bath Stone was extensively used on domestic and civil engineering projects such as bridges; the Royal National Hospital for Rheumatic Diseases, founded in 1738, was designed by John Wood the Elder, built with Bath stone donated by Allen. It is a Grade II listed building.
There is a fine pediment on the building, in Bath stone, which depicts the parable of the good Samaritan. St Stephens church, situated on Lansdown Hill in Bath, was constructed from a limestone sourced from the Limpley Stoke mine, situated in the Limpley Stoke Valley; the church has been restored. The material has been used outside Bath itself. Claverton Pumping Station at Claverton, built of Bath Stone in about 1810, pumps water from the River Avon to the Kennet and Avon Canal, using power from the flow of the River Avon; the stone was used for the Dundas Aqueduct, 150 yards long, has three arches built of Bath Stone, with Doric pilasters, balustrades at each end. Much of Bristol Cathedral was built of Bath Stone, the Wills Tower, the dominant feature of the Wills Memorial Building, is constructed in reinforced concrete faced with Bath and Clipsham stone. Bristol's Cabot Tower was faced with Bath Stone. Arno's Court Triumphal Arch was built from Bath stone in about 1760, was dismantled before being rebuilt in its current location.
Bath Stone was favoured by architect Hans Price, who designed much of 19th century Weston-super-Mare. In Barnstable, the 1855 construction of Butchers Row used Bath Stone. In London, the neo-classical Georgian mansion Lancaster House was built from Bath Stone in 1825 for the Duke of York and Albany, the second son of King George III, as was St Luke's Church, Chelsea in 1824, several other churches, including Church of Christ the King, were built from the material. Apsley House, the town house of the Dukes of Wellington, was remodelled by the 1st Duke, using in Bath Stone cladding over the original red brick. In Reading, the original building of the Royal Berkshire Hospital of 1839, together with the wings added in the 1860s, are built of Bath Stone, with slate roofs, they are now listed grade II* by English Heritage. In 1860, the nearby Reading railway station, incorporating a tower and clock, was constructed by the Great Western Railway using Bath Stone, the company used it for Chippenham railway station.
Other mansions which have used Bath Stone include: Gatcombe Park, Goldney Hall, South Hill Park, Spetchley Park. In 2002 the East End of Truro Cathedral was renovated and restored with some of the ornate Bath Stone replaced with harder-wearing Syreford stone. In 2005 the West Front was restored similarly. Both projects were supervised by MRDA Architects of the Cathedral architects. Bath Stone was mined underground in Somerset. In the early 18th century, Ralph Allen promoted the use of the stone in Bath itself, demonstrated its potential by using it for his own mansion at Prior Park. Following a failed bid to supply stone to buildings in London, Allen wanted a building which would show off the properties of Bath Stone as a building material, he acquired the stone quarries at Bathampton Down Mines. Hitherto, the quarry masons had always hewn stone providing blocks of varying size. Wood required stone blocks to be cut with clean edges for his distinctive classical façades; the distinctive honey-coloured Bath Stone was used to build the Georgian city.
Stone was extracted by the "room and pillar" method, by which chambers were mined, leaving pillars of stone to support the roof. Allen built a railway line from his mine on Combe Down which carried the stone down the hill, now known as Ralph Allen Drive, which runs beside Prior Park
South Wales Coalfield
The South Wales Coalfield is a large region of south Wales, rich in coal deposits the South Wales Valleys. It supported a large part, but not all, of the coal industry in Wales; the South Wales Coalfield extends across parts of Pembrokeshire, Swansea, Neath Port Talbot, Rhondda Cynon Taf, Merthyr Tydfil, Blaenau Gwent and Torfaen. It comprises a exposed synclinorium with a varying thickness of Coal Measures deposits with thick, workable seams in the lower parts and thinner and sparser seams in the upper parts, together with a development of sandstones. See the Geology of South Wales; these sandstones have been much used in building construction and give rise to bleak uplands rising 300–600 metres above sea level between the steep-sided valleys in which most deep mines were developed. The coal increases in grade or "rank" from east to west, with bituminous coals in the east, anthracite in the west to the north and west of Neath; the Rhondda Valley was known for steam coals which fuelled steamships of the 19th and early 20th centuries.
Communications along the valley floors provided the main routeways for exporting coal south to ports and docks such as Newport Docks, Cardiff Docks and Barry Docks. Early activity was by levels or adits driven into coal seams from outcrops in the valley sides. Development of the coalfield proceeded actively from about 1850, when deep mining became significant in the entirely rural Rhondda Valley. Tramway-fed canals such as the Swansea Canal and Glamorganshire Canal were supplemented, superseded, by the development of numerous competing railway branches which fed docks principally at Swansea, Newport and Barry. Colliery shafts were sunk as deep as 800 yards in order to reach the thicker, better quality seams. Iron ore was extracted from the coal measures, principally from the north crop area; the availability of coal and nearby limestone gave rise to a substantial local iron and steel industry, perpetuated in the 20th century by the location of modern steelworks at Ebbw Vale and Cardiff and Port Talbot.
These used imported iron ore. Coal fuelling of Royal Navy ships was challenged from 1904 when strategists including Admiral "Jacky" Fisher and Winston Churchill argued for oil-firing of the steam engines in new ships. By the start of World War I, both the Queen Elizabeth-class and the Revenge-class battleships were oil-fired – where oil was used for both quick-start steaming, sprayed on burning coal to extend their range – as well as a number of cruiser and destroyer classes produced since 1904. Oil-fired ships still therefore needed to carry coal as their primary fuel. Hence by the time of the Battle of Jutland in May/June 1916, only a sixth of the Grand Fleet was oil-fired. Further, that summer the British suffered a number of losses of oil tankers, had to instruct oil-fired ships to restrict their fuel consumption, hence speed; when the United States entered the war in April 1917, the British instructed the United States Navy to send only coal-fired ships to assist them. To assist the Royal Navy, from the outset of the war the Government and railway companies ran what were termed "Jellicoe Specials", high-speed coal carrying freight trains that ran from South Wales to north-east Scotland, by ship to Scapa Flow.
Running to Dingwall, they were shipped to Scrabster through Thurso. However, inadequate capacity in port and rail facilities at these locations meant that from January 1915, all naval ordnance and medical supplies were sent by rail to Aberdeen, from mid-1915 Grangemouth. By the end of WWI, the Royal Navy had 33 dreadnoughts and 9 battle cruisers, with 10 and 2 entirely oil fuelled. However, after WWI, the move to oil-firing was extended to other areas, including the railways, a key strategic factor in the economic hardship which struck the coalfield after the war. Coal workings were over-expanded in the late nineteenth century, the Welsh coal owners had failed to invest in mechanisation. By the inter-war period the South Wales Coalfield had the lowest productivity, highest costs and smallest profits in Britain. Hardship continued through the 1926 general strike, the great depression of the 1930s, World War II and thereafter; the 1937 novel The Citadel and the 1939 novel How Green Was My Valley describe such hardship, as do the poems of Idris Davies the miner and poet of Rhymney.
New collieries in the western part of the coalfield where anthracite is found, were developed into the 1960s by the National Coal Board. Following the general collapse of the UK coal industry, most pits closed during the 1980s, with factors such as exhaustion of reserves and geological complexity adding to their problems; the last deep mine, at Tower Colliery on the north crop, ceased mining in January 2008. However, a few small licensed mines continue to work seams from outcrop, on the hillsides. Although some areas of the coalfield are worked out, considerable reserves remain. However, the geological difficulties, which resulted in the closure of Nantgarw colliery, make the cost of significant further extraction high; the coalfield experienced a late-stage development when opencast mining was commenced on a large scale