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Carboniferous Limestone is a type of limestone rock, which was laid down in Great Britain and Ireland in the Dinantian stage of the Carboniferous period. Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere See also Kingdom of Great Britain Great Britain (Breatainn Mhòr Prydain Fawr Breten Veur Graet Breetain is the larger of the two main islands Ireland (pronounced /ˈaɾlənd/ Éire) is the third largest island in Europe, and the twentieth-largest island in the world Dinantian is the name of a series or Epoch from the Lower Carboniferous system in Europe The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 It was formed between 363 and 325 million years ago. It is one of the three most common types of limestone found in Britain, along with chalk and Jurassic limestone. Chalk (ʧɔːk is a soft white porous Sedimentary rock, a form of Limestone composed of the Mineral Calcite. Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3

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Outcrops

Cross-section of a Carboniferous limestone bored by Jurassic organisms; borings include Gastrochaenolites (some with boring bivalves in place) and Trypanites; Mendip Hills, England; scale bar = 1 cm.
Cross-section of a Carboniferous limestone bored by Jurassic organisms; borings include Gastrochaenolites (some with boring bivalves in place) and Trypanites; Mendip Hills, England; scale bar = 1 cm. Bivalves are Molluscs belonging to the class Bivalvia. They have two-part shells and typically both valves are symmetrical along the hinge line The Mendip Hills (commonly called The Mendips) are a range of Limestone hills situated to the south of Bristol and Bath in Somerset

The Mendip hills consist of Carboniferous limestone, showing notable geomorphological features, including Cheddar Gorge and the Avon Gorge near Bristol. The Mendip Hills (commonly called The Mendips) are a range of Limestone hills situated to the south of Bristol and Bath in Somerset For the gorge in Scotland with the same name see Avon Gorge Falkirk The Avon Gorge ( is a 1 Bristol ( ˈbrɪstəl is a city, Unitary authority and ceremonial county in South West England, west of London Outcrops occur around the edge of the coalfields in south and north Wales, where Eglwyseg Escarpment, near Llangollen and Great Ormes Head are prominent features. The Great Orme ( Welsh: Y Gogarth or Pen y Gogarth) is a prominent Limestone headland on the north coast of There are a few outcrops in Shropshire such as Titterstone Clee hill and Little Wenlock. Shropshire (ˈʃrɒpʃɪə/ /-ʃə alternatively known as Salop or abbreviated in print only Shrops, is a county in the It covers much of the area of the Derbyshire Peak District. History The area that is now Derbyshire was first visited probably briefly by humans 200000 years ago during the Aveley Interglacial as evidenced by a Middle The Peak District is an upland area in central and northern England, lying mainly in northern Derbyshire, but also covering parts of Cheshire, Greater However, the main outcrop in terms of area is in the Pennines and surrounding the Lake District. The Pennines are a low-rising Mountain range in Northern England and southern Scotland. The Lake District, also known as The Lakes or Lakeland, is a rural area in North West England.

Characteristics

Carboniferous limestone is a sedimentary rock made of Calcium carbonate. It is generally light-grey in colour, and is hard. It was formed in warm, shallow tropical seas teeming with life. The rock is made up of the shells and hard parts of millions of sea creatures, some up to 30 cm in length, encased in carbonate mud. Fossil corals, brachiopods and crinoids are very much in evidence as components of Carboniferous limestone; indeed the rock is full of fossils. Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the Echinoderms (phylum Echinodermata

Carboniferous limestone has horizontal layers (beds) with bedding planes, and vertical joints. These joints are weaknesses in the rock, which are exploited by agents of both denudation and weathering. Denudation is the process by which the removal of material through means of Erosion and Weathering, leads to a reduction of elevation and relief in landforms and Weathering is the decomposition of earth rocks, Soils and their Minerals through direct contact with the planet's Atmosphere. They also lead to the most important characteristic of Carboniferous limestone - its permeability. Permeability in the Earth sciences (commonly symbolized as κ, or k) is a measure of the ability of a material (typically a rock or unconsolidated Water seeps through the joints in the limestone. This creates a landscape that lacks surface drainage but which has all manner of characteristic surface and subsurface features. The Carboniferous Limestone has been folded and faulted by massive Earth movements which can be seen by the fact that the rocks are now above sea-level and no longer horizontal. The rocks generally dip (slope) gently eastwards and, in some places, clear folds in the rock can be seen especially at the Great Orme and Bryn Alyn (Denbighshire).

Surface Features

The 'classic limestone walk' is a circular 10 km route from the field centre on the north side of Malham Tarn to the village of Malham, UK via Watlowes Valley and back again via Gordale Scar. Malham Tarn is a Glacial lake near the village of Malham in the Yorkshire Dales, England. Gordale Scar is a dramatic Limestone ravine close to Malham, North Yorkshire, England. The walk has an example of nearly every significant surface limestone feature.

Small surface depressions called shakeholes, which are 1-3m deep and 3-5m across, form as a result of the subsurface collapse of limestone. Shakeholes are very common throughout the Yorkshire Dales. Larger depressions are called dolines.

Streams flowing from higher impermeable slopes sink into the ground when they reach permeable limestone. During dry spells all water sinks very quickly on reaching the limestone, through sinkholes. A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or Cenote, is a natural depression In wetter conditions water flows a greater distance across the limestone as underground channels and chambers fill up. Large sinkholes are called 'swallowholes' or 'potholes'. Gaping Gill, Alum Pot and the Buttertubs are well-known examples. Gaping Gill (also known as Gaping Ghyll) is one of the unmistakable landmarks on the mountain of Ingleborough in North Yorkshire, a 105

Dry valleys are valleys without streams. Watlowes Valley is an excellent example. It was formed originally by a subglacial meltwater stream which existed during the last major Ice Age. 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 After the ice retreated, the valley was further developed by a meltwater stream flowing across the limestone while it was frozen solid. Watlowes Valley is a particularly good example of a dry valley because it has a textbook profile - the south-facing side is less steep than the north-facing side. This results from the weathering and mass movement processes that have operated in the post-glacial period.

A limestone pavement is an area of almost bare, flat rock and is arguably the most fascinating feature of any area of carboniferous limestone. A limestone pavement is a natural Karst landform consisting of a flat incised surface of exposed Limestone that resembles an artificial pavement They develop after the rock has been exposed by the scouring action of an ice sheet or glacier. An ice sheet is a mass of Glacier Ice that covers surrounding terrain and is greater than 50000 km² (20000 mile²) "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. Existing joints are subsequently exploited by the action of chemical weathering carbonation to form deep grykes and rounded blocks called clints. Grykes have a habitat of their own, which encourages the growth of shade-loving ferns such as hart's tongue and dog's mercury.

During the last Ice Age, Malham Cove - the most spectacular feature in the Yorkshire Dales - was a waterfall comparable in size to the Horseshoe Falls of Niagara. Malham Cove is a natural Limestone formation near Malham, North Yorkshire, England. The Horseshoe Falls, also known as the Canadian Falls, is a Waterfall on the Niagara River, located mostly on the Canadian side of At the end of the Ice Age the limestone, which had been frozen solid, once again became permeable, allowing the water to disappear through its joints. Now Malham Cove is a high cliff (83m high) - it is completely dry, and a great attraction to rock climbers.

A gorge is a steep-sided valley, generally formed in a limestone area as the result of the collapse of a roof above a cave system. For the song see CANYONMID. For the band see Canyon (band. A canyon (rarely cañon) or gorge In Geology, a valley (also called a vale, dale, glen or strath and near or in Appalachia, a draw) is Gordale Scar is an excellent example. Gordale Scar is a dramatic Limestone ravine close to Malham, North Yorkshire, England.

Sub-Surface Features

The most common examples of subsurface features in a limestone landscape are caves. In the Yorkshire Dales, there are numerous caves, three of which - Ingleborough Caves, White Scar Caves and Stump Cross Caverns - are now show caves for the public. The Yorkshire Dales (also known as The Dales) is the name given to an upland area in Northern England. White Scar Caves are a network of caves under Ingleborough hill in the Yorkshire Dales National Park in the North of England. Stump Cross Caverns is a Limestone cave system between Wharfedale and Nidderdale in North Yorkshire, England.

The caves themselves and their associated formations vary greatly in size, but they all depend on the process of carbonation for their creation. Carbonation is a reversible process: it results in the redeposition of calcite, and the development of stalagmites, stalactites, straw stalactites, helictites, pillars and flowstone. A stalagmite (from the Greek stalagma ("Σταλαγμίτης" "drop" or "drip" is a A stalactite ( Greek stalaktites, (Σταλακτίτης from the word for "drip" and meaning "that which drips" is a type of Speleothem A helictite is a Speleothem found in Limestone Caves that changes its axis from the vertical at one or more stages during its growth Flowstones are composed of sheetlike deposits of Calcite formed where water flows down the walls or along the floors of a Cave. the rate of growth of these formations is about 1cm per 200 years - it is therefore an extremely slow process. Some stalactites may be millions of years old.

Economics

Carbonifereous limestone has not been much used as a building stone, because it is brittle, but it is extensively quarried for other purposes:

See also

The following is a list of various types of Limestone according to location
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