Geology and geomorphology -Limestone Pavement Conservation Limestone Pavement Conservation Geology and geomorphology Limestone pavement is a habitat with a high geological interest. Forms of limestone pavement can be found in many places in the world, especially in Alpine and Mediterranean areas, but these lack the distinctive surface patterning seen on British pavements. How limestone pavements form Limestone is a hard sedimentary rock consisting of calcium carbonate, formed by the deposition of plant and animal remains on the sea floor and is thus known as a calcareous rock. Limestones often contain the visible remains (fossils) of shells and corals. As limestone is a sedimentary rock, it is laid down in layers or ‘beds’ separated by ‘bedding planes’ which are caused by changes in deposition rates or content of material deposited. Limestone pavements in England, Wales and Ireland are mainly formed on deep beds of Carboniferous limestones which were deposited about 350 million years ago. Those in Scotland can be found on more ancient Durness and Dalradian limestones. The formation of limestone pavements in the UK and Ireland began with the scouring of the limestone by kilometre thick glaciers during the last ice age.

The weight of the ice removed the soil that lay over the limestone, and also fractured the limestone along existing horizontal surfaces of weakness known as bedding planes. Fractured rocks were stripped away leaving level platforms of limestone on which a thick layer of boulder clay (glacial till) was deposited as the glaciers retreated. Wind blown material was then deposited on top of the boulder clay. This external material is particularly important for soil formation, as limestone does not weather down into soil which would mean if there had been no glacial deposits, there would have been no soil development. From the flat limestone surfaces, the characteristic features of limestone pavement have been formed by water in the glacially deposited soil exploiting cracks and fissures in the rock such as bedding planes and joints (lines of weakness in the rock generally running at 90o to bedding planes). Also deposited on the limestone platforms were erratic rocks, ranging in size from pebbles to huge boulders. These erratics, often rocks of a different type to the limestone, are one of the most visible indicators of glaciation on limestone pavements. Karst scenery Limestone pavement is a type of karst landform.

Karst is the word for an area of soluble rock in which the landforms are of a solutional nature (i.e. they are caused by water dissolving the rock ) where drainage is usually underground through rock fissures rather than in surface streams. Karst, a term originating from a limestone region in the former Yugoslavia, is derived from the Slovenian word kras, meaning a bleak, waterless place. It is used to describe a landscape containing erosional features such as bare pavements, subterranean water systems, dry valleys, dolines which are small to medium sized closed depressions with no surface outlet for water (hundreds of metres in diameter and tens of metres deep); and poljes which are large depressions with diameters of 1km upwards and depths of over 50m or so. It is the layer of debris left by the retreating glaciers and also by wind deposits that hold the key to the development of the characteristic limestone pavement landforms over the last 10,000 years. The karst landforms were formed by the gradual dissolving of the limestone by mildly acidic water seeping through the forest cover which had become established on the soil above the limestone platforms.

If this glacial debris had not been in position, then the weathering processes that form limestone pavements could not have taken place. Clints and Grikes Due to the solubility of limestone, limestone pavements are associated with some very curious and unusual landforms. The most characteristic surface feature of limestone pavements is their division into blocks, called clints, bounded by deep vertical fissures known as grikes. Clints and grikes form under relatively deep cover of soil where water, carrying carbonic acid which is formed from dissolved carbon dioxide as well as organic acids from decaying vegetation, picks out vertical lines of weakness (joints) in the rock. These fissures widen over the years as the acidic water preferentially attacks the lines of weakness. Grikes take many thousands of years to form under the soil as the rate of solution is slow. Over time, the soil on the top of the limestone platform began to disappear down the newly eroded grikes, and was gradually eroded from the tops of the platforms. Some of the material lost into the grikes was washed deep into the drainage systems of the limestone pavements through connecting fissures, leaving open grikes of a metre or more in depth.

These erosional processes were increased when forest clearance and grazing was introduced by humans onto the buried pavements leading to a more rapid exposure of pavements. Runnels, Pits and Pans As well as clints and grikes, limestone pavements also have a number of characteristic surface formations. These are known as runnels, pits and pans and take different forms depending on the structure of the pavement on which they form. Runnels are gutter-like channels eroded out of the surface of the limestone which drain into grikes. The formation of runnels takes place under a shallow layer of soil. Runnels formed on steeply sloping limestone are usually close together and parallel, whereas runnels forming on gentle slopes take dendritic or branched forms which can be looked at as a miniature river system. Pits and pans are small scale solution features (i.e. formed by water and acids dissolving the limestone) found on the tops of clints. Pits are deep and free draining into the subterranean limestone drainage system. Pans are shallow, have an impervious base and hold water. Both of these features also form under shallow soil cover.

Some research indicates that the deeper features can be formed by humic acid from the root balls of trees resting against the limestone and dissolving it into the characteristic round bottomed features of pits and pans. When solution features on a limestone pavement are exposed due to soil loss, they become more weathered and ‘sharper’ in appearance. It is possible to differentiate newly exposed pavement from pavement which has been exposed for longer periods of time by looking at the sharpness Limestone pavement and Karren features The limestone features described above have specific scientific names and are known as ‘Karren’. Karren is a general term used to describe the total complex of superficial micro-solutional features of soluble rocks such as limestone and gypsum. Karren are particularly common on limestone pavements. Karren forms include sharp-ridged grooves (rillenkarren) and their larger, elongated cousins (rinnenkarren), as well as rounded runnels formed beneath a soil cover (rundkarren). Other forms include the ubiquitous solutional hollows (kamenitzas), grikes (kluftkarren), clints (flachkarren), and horseshoe shaped stepped structures (trittkarren).

References for this section Grikes - definition of grikes by The Free Dictionary Grikes - definition of grikes by The Free Dictionary gryke n (Geological Science) a solution fissure, a vertical crack about 0.5 m wide formed by the dissolving of limestone by water, that divides an exposed limestone surface into sections or clints [C20 in geological sense: from northern dialect] Want to thank TFD for its existence? Tell a friend about us , add a link to this page, or visit the webmaster's page for free fun content . Link to this page: limestone pavement References in periodicals archive ? And the rolling hills of the Burren are composed of limestone pavements, crisscrossed with cracks known as grikes, and isolated rocks called clints. Copyright © 2003-2017 Farlex, Inc Disclaimer All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional.

Clints and grikes – Chip's journey Clints and grikes Clints and grike We’ve walked on more interesting trails in Newfoundland than I can count, and those are a tiny fraction of the possibilities. Many are in National or Provincial Parks; some are on private land or Crown Land . Since 95% of Newfoundland and Labrador is provincial Crown Land, there’s a lot to explore. Some of the trails have been developed by small towns, including outport communities. For example, Flower’s Cove on the Great Northern Peninsula has the White Rocks Walking Trail. This wanders across a limestone barrens, where I learned firsthand about clints and grikes. Limestone barrens Limestone barrens are odd, unforested areas with what appear as large, limestone paving stones, mortared with mosses, small conifers, wildflowers, and other flora. These are unique ecosystems with extremes hot and cold, plus cycles of drought and flooding and frost. They represent less than 1% of the total area of the island, but host 10% of the rare plants. The limestone pavement of the barrens is a type of karst landform.

These formations have blocks, called clints, separated by deep vertical fissures known as grikes. Karst is derived from the Slovenian word kras, meaning a bleak, waterless place. Solied pants From experience, I strongly advise you to be careful, stepping only on the clints. This advice is not always easy to follow, since plants grow up through the grikes and often spill over onto the clints. Thus it’s possible to step on what seems to be a thin layer of green on the clint and find your foot going deep into a grike. This happened to me near the end of a walk. My left foot sank down nearly up to the knee. I the fell forward hitting both knees on the clint. I was just lucky that I hadn’t caught the foot more, or I might have had a twisted ankle or even a broken foot, possibly one wedged into the grike. Since I was walking alone at the time, I might have come to understand truly what Slovenians mean by kras. Instead, I suffered no worse than embarrassment and soiled pants.

Rate this: Limestone Pavement (images of British & Irish biodiversity) Limestone Pavement British & Irish distribution: principally in northern England, northwestern Scotland and western Ireland, with scattered local development elsewhere. World distribution: no data, but potentially able to develop wherever massive sediments of hard limestone are subject to exposure and weathering by rainfall. Clints and grikes (or, being Irish, slabs and scailps), the Burren, Co. Clare, 1973 FORMATION Limestone, fundamentally, is calcium carbonate, formed from deposits of varying degrees of purity, particularly in warm, shallow seas. Many organisms, particularly many types of microorganism, secrete calcium carbonate as a by-product of metabolic activity or for formation of protective coverings, and their remains may make up a significant proportion of the resultant limestone rock. Many limestones are relatively soft, notably chalk and the oolitic limestones in the south of England, and these limestones weather too quickly to form pavements. However, where the limestone is hard and horizontally-bedded, typically scoured by glacial action, weathering is more pronounced along the joints and then pavements can form.

Almost all such pavements in the British Isles are formed from the massive limestones laid down in the Carboniferous era - important examples including the Craven Pennines (notably around Ingleborough) in Yorkshire, Gait Barrows in Lancashire, Hutton Roof Crags in Westmorland (Cumbria) and the Burren in western Ireland. However, the much older Cambrian limestone of north west Scotland is also hard enough for localised pavement formation, as in the vicinity of Durness, West Sutherland. Limestone is readily dissolved by rainwater that has been acidified by dissolved carbon dioxide or organic acids and this water can act on the rectangular joints, deepening and widening them to form fissures that may become several metres deep. These fissures are commonly termed 'grikes' (originally a Yorkshire word and the word most familiar to ecologists), or in Ireland they are known as 'scailps'. The slabs, usually flat on top, that are left between the grikes, are 'clints'.

The type of landscape produced is an example of karst, "terrain in which soluble rocks are altered above and below ground by the dissolving action of water and that bears distinctive characteristics of relief and drainage." (J.N. Jennings, quoted from Huggett, 2003). Broader terms used for the surface features brought about by solution effects on kimestone are 'karren' and 'lapiés'. Depending on the nature of the limestone and the action of the weather, the clints may remain intact, or else may be broken up to form 'shattered limestone pavements', with fragments of all sizes laying loose on the surface and falling into the fissures as they form. Extensive shattered limestone pavement, the Burren, Co. Clare, 1973 Any depressions on the clint surfaces will trap rainwater which in turn will allow the growth of algae, notably the cyanobacterium ('blue-green alga'), Nostoc, which secretes protective mucilage which will protect it from rapid drying (though it does survive extreme desiccation in the summer months). Nostoc itself produces the organic acids that further dissolve the limestone by biological weathering to form solution hollows.

Solution hollows, occupied by and no doubt largely caused by the cyanobacterium, Nostoc. Photograph: the Burren, Co. Clare, 1973 It is a necessary part of the concept of a limestone pavement that the rock is exposed (though similar rock geomorphology may exist under soil covering). Disagreements exist on the extent to which some pavements have ever been soil-covered following glacial scouring. However, once joints in the bedrock have opened through solution processes, existing soil and any other drift material is likely to be lost into the grikes as they form, and may indeed be lost to subterranean cave systems. Soil may, itself, be involved in the initiation of limestone pavement or other karren features. Any acidity in rain percolating through a calcareous (calcium-rich) soil is likely to be neutralised by the bases in the soil, and so the soil protects the rock below. If the soil itself is acidic, not only will this neutralisation not occur, but the acidity will be reinforced by organic acids from the soil. The acid waters will penetrate joints, eventually dissolving large grikes, into which the soil may be washed, exposing the bedrock surface.

Since erosion under a wet soil results from continuous corrosive soaking, as distinct from the episodic nature of rainfall events, the rock surface my be eroded and dissected in a more irregular manner, producing bizarre shapes in the eventually exposed rock. Detailed discussion of these processes is given by Trudgill (1985). HABITATS The best limestone pavements tend to be upland or on exposed coasts, and combinations of wind and, more particularly, grazing often prevent extensive colonisation of the pavement surfaces by vegetation. On the other hand, the grikes provide a microhabitat that is sheltered, humid and inaccessible to sheep and other large grazing animals. An apparently hostile landscape can contain a rich variety of plant species, including a number that are nationally rare or scarce. Where thin soils can accumulate on limestone pavements, these are typically rendzina soils with the shallow humus layer grading into a raw mixture of loam and limestone fragments directly above the bedrock, with no zone of deposition as is the case with mature soils. High levels of free calcium carbonate reduce the availability of other cations, leading to deficiencies of iron and other plant nutrients.

Thus the habitat is suitable only for those species that can tolerate these conditions, species that in many cases are intolerant of competition from more vigorous plants on richer soils and so rare or of restricted distribution. Many are calcicoles, lime-demanding species (though it is often difficult to distinguish a requirement for high calcium levels from high tolerance and competitive restriction to such habitats). The thin surface soils are, however, also liable to lose minerals as a result of leaching, the minerals dissolving in rainwater and being lost in surface run-off and transport down into the grikes and bedrock. This can lead to formation of limestone heath, in which lime-intolerant (calcifuge) species such as Heather (Calluna vulgaris) can grow side by side with lime demanding species - the co-existence based partly on different rooting levels, with the calcifuges rooted in the more acidic surface layers. Within the grikes there can be greater accumulations of leaf-litter, leading to 'woodland' conditions (with or without the trees!), with shade, humidity and accumulations of richer soil.

Typical woodland herbs, such as the Primrose (Primula vulgaris) and Dog's Mercury (Mercurialis perennis), can grow well, and nitrogen-loving species such as Stinging Nettle (Urtica dioica) may find a suitable niche. Hart's-tongue Fern (Phyllitis scolopendrium) is, like most ferns, shade-tolerant, and is able to reach large size in the shelter and humidity of grikes. Photograph: the Burren, Co. Clare, 1973. Maidenhair Fern (Adiantum capillus-veneris) is a rare species in the British Isles, restricted to scattered, very sheltered, frost-free locations on damp, lime-rich rock-faces along the west coasts of England, Wales and Ireland. It is, however, a characteristic species of the deeper grikes on the Burren. Here it is shown on the sides of a deep solution hollow. Photograph: the Burren, Co. Clare, 1973.

Baneberry (Actaea spicata) is a nationally scarce species in Great Britain, with mostly small populations restricted to a band of localities across northern England. It is intolerant of competition but highly shade tolerant (Abbott in Stewart et al., 1994) and is frequent in the grikes of a few limestone pavements. Photograph: near Ingleborough, Yorkshire, 1972. Pavements usually seem largely treeless, but appearances can be deceptive. Deeper, wider grikes can contain quite mature trees, notably Ash (Fraxinus excelsior). Trees and shrubs remain relatively dwarfed, effectively in a 'bonsai' state, emerging shoots being pruned by wind and grazing animals. Sometimes, in exposed places, a tree or shrub can emerge from a grike but then is forced by the wind to grow prostrate over the rock surface. Ash (Fraxinus excelsior) (left) and Holly (Ilex aquifolium) (right), emerging from grikes, growth flattened by the prevailing winds. Photographs, the Burren, Co. Clare, 1973.

Burnet Rose (Rosa pimpinellifolia), a shrub of coasts and lime-rich habitats, at home in the grikes of the Burren, photographed 1973. Where pavements are protected from grazing and have a degree of shelter from strong winds, scrub can begin to develop. On some pavements this is predominantly Hazel (Corylus avellana), but, as noted above, Ash can be a colonist of grikes and this can continue to grow into relatively large trees. Eventually, as more leaf-litter accumulates on the clint surfaces, they can be colonised by mats of bryophytes, and eventually the whole pavement can become wooded. Notably this has happened at Colt Park Wood, part of the Ribblehead Woods SSSI in Yorkshire, where there is mature ashwood on pavement. Forest of this type fits the 'Fraxinus excelsior-Sorbus aucuparia-Mercurialis perennis woodland' (W9) of the National Vegetation Classification and there is good discussion of the climatic and edaphic factors that characterise this type of forest in Rodwell et al. (1991).

The fragmentary 'forest' in the grikes of many open pavements undoubtedly also belongs here. It should be noted that wooded limestone pavement should be rated DANGEROUS in fieldwork safety assessment. Bryophyte and other vegetation mats close over deep grikes but will not support human weight. Testing of every step is vital. (Note too that open pavements may be at least hazardous, especially where there are wide, deep grikes, or where clints are unstable, or when the rock surface is wet, and that bad weather may also make these DANGEROUS as defined by UWS fieldwork safety guidelines.) Limestone pavement protected from grazing, near Ingleborough, Yorkshire, 1973. Here, Ash (Fraxinus excelsior) trees were growing from the grikes and, remarkably, Heather (Calluna vulgaris), a calcifuge, was growing well on the pavement surface. The high rainfall in this upland site was sufficient to cause rapid leaching of the thin surface soils and 'limestone heath' was developing, including other calcifuge species such as Tormentil (Potentilla erecta). The area of pavement shown in this photograph no longer exists.

Not all vegetation is confined to the grikes. Where pavements have eroded to different levels, open vegetation or more continuous turf can develop on the thin soils between larger limestone blocks. Here may be many of the plant rarities, intolerant of the competition from more vigorous and coarser species on deeper soils. Many have bright, showy flowers, contributing aesthetic beauty as well as scientific interest. A terraced pavement with patches of floristically rich turf, the Burren, Co. Clare, 1973. Mossy Saxifrage (Saxifraga hypnoides), is a typical pavement plant, able to spread onto the bare rock surfaces in compact mats or cushions that withstand the prevailing winds. It is part of a taxonomically difficult group of montane plants that include several grown as alpines and rock plants in gardens. Photograph: near Ingleborough, Yorkshire, 1973. Hoary Rockrose (Helianthemum oelandicum), is able to form mats on open limestone rubble and in thin turf, again with the facility to spread onto clint surfaces. Photographed here is subsp.

piloselloides, the Irish and Pyrenean subspecies, which has larger, less densely hairy leaves than the main subspecies in Britain and is almost confined (in Ireland) to the Burren. Photograph: the Burren, Co. Clare, 1973. Early Purple Orchis (Orchis mascula), is sometimes abundant on the thin soils over limestone outcrops. Photograph: near Ingleborough, Yorkshire, 1973. Another ecological grouping of plants that can find a niche on limestone pavements are the 'spring ephemerals' (therophytes). The open surfaces of the clints are a hostile habitat in the summer, not only dry but also liable to heat up in the sun to temperatures that will kill much plant growth. (Plants themselves, in the same ambient temperatures, have efficient re-radiation to avoid overheating.) Depressions and shallow solution hollows in the surface can accumulate a little humus and mosses can grow on these surfaces in the wetter, mainly winter months. Such mosses must be highly tolerant of desiccation and able to revive in wetter weather.

However, small annuals, often germinating in autumn in the moss carpets and overwintering as small rosettes, can also survive these conditions by completing their life-cycles early in the year. Large populations of these tiny plants in April and May may have died, dried up and vanished by mid-summer, yet their seeds are surviving in the moss and rubble, ready again for the autumn rains. Rue-leaved Saxifrage (Saxifraga tridactylites), a tiny annual, often only 2-3 cm in height though sometimes taller, part of the spring therophyte community and disappearing completely by early summer. Photograph: near Ingleborough, Yorkshire, 1973. ANIMAL LIFE Undoubtedly the grike microhabitat suits many invertebrates, but the overall habitat is not notable for specialised vertebrates, except in that pavements, particularly those colonised by scrub, provide refugia for species becoming more restricted by intensive agriculture. The Common Lizard (Lacerta vivipara), while by no means restricted to limestone habitats, does undoubtedly benefit from the basking opportunities provided by the tops of the clints - enhanced by the reflectivity of the limestone rock.

In Ireland, the grikes and crevices of the Burren provide good hunting territory for the Irish Stoat (Mustela ermina hibernica) [a trinomial name as it is a separate subspecies], and the scrubbier areas of the Burren are the stronghold in Ireland for the Pine Martin (Martes martes), though whether the latter can be said to be associated specifically with limestone pavements is doubtful. A claim for a moth of limestone pavements can be made for the Burren Green (Calamia tridens occidentalis), an attractive bright green moth, known in the British Isles only from the Burren and first discovered there as late as 1949. The food plant is apparently Blue Moor-grass (Sesleria caerulea) (Skinner, 1998), a very characteristic grass of the pavements. A moth of the major limestone masses in northern England is the Least Minor (Photedes captiuncula), which is also on the Burren as a distinct subspecies.

A nicely produced account of Burren wildlife is that of D'Arcy & Hayward (1992), including an authoritative consideration of threats to and conservation of this unique area. However much of the book considers fens, turloughs (temporary lakes) and other features of the Burren limestone that are outside the scope of this present summary of the limestone pavement habitat. CONSERVATION Limestone pavements have long survived because they have been resistant to many human activities. Only where pavements were thin was it possible to clear the surface stone to create more continuous pasture - and indeed some such old pastures themselves are of considerable floristic interest. However, mechanical breaking and removal of limestone pavements has become more feasible. A number have been lost to agriculture, with farmers not unreasonably wanting to extend their usable land (and to reduce loss of livestock into grikes). Arguably of greater recent impact has been the removal of limestone blocks for horticulture, with weathered (particularly water-worn) limestone considered of great value in landscape gardening schemes, as well as finding ready sales to amateur rock gardeners via garden centres. The garden rockery can represent irreversible damage and destruction of the habitat that gardeners are trying to recreate.

SSSI notifications have provided only weak protection, particularly where 'agricultural use' of land is effectively unchanged. The Wildlife and Countryside Act (1981) has provision for Limestone Pavement Orders (LPOs), whereby statutory protection can be given to 'areas of limestone wholly or partly exposed on the surface of the ground and fissured by natural erosion'. The Act not only prohibits removal of limestone, but also disturbance and damage. The casual visitor to a designated site who takes home a few lumps of limestone in the boot of his car commits an offence, just as does someone involved in commercial clearance. Sadly, illegal destruction of limestone pavements continues in Britain, and destruction of pavements in Ireland is also a serious concern. Limestone pavement is a priority habitat included in the UK Biodiversity Action Plan (see link below). References: D'Arcy, G., & Hayward, J., (1992). The natural history of the Burren, Immel Publishing, London. Huggett, R.J., (2003). Fundamentals of geomorphology, Routledge, London and New York. Rodwell, J.S., et al. (1991).

British plant communities, 1: woodlands and scrub. Cambridge Univ. Press, Cambridge. Skinner, B., (1998). Colour identification guide to moths of the British Isles, 2nd ed., Viking, London. Stewart, A., Pearman, D.A., & Preston, C.D., (1994). Scarce plants in Britain, JNCC, Peterborough. Trudgill, S., (1985). Limestone geomorphology, Longman, London and New York. Links: The 'official' current statement on conservation status of British limestone pavements (Dr. J.S. Conway, Royal Agricultural College) - further images of limestone pavements and summary of conservation initiatives BBC - Education Scotland - Upland Limestone - Surface Features - Limestone Pavement Limestone Pavements are bare limestone rock surfaces composed of slabs of rock (clints), separated by variable-width vertical cracks (grikes). These grikes have developed by weathering and enhanced solution along joints. Composed principally of calcite, limestone is vulnerable to chemical weathering by water (solution) and dissolves easily.

In the Yorkshire Dales, exposure of very extensive pavements may be partly an example of the stripping of soil by moving ice during the last glaciation period more than 10,000 years ago. The Burren: Limestone Pavements, Clints and Grykes Home | Library Catalogue | Forums | Foto | Maps | Archaeology | History | Search this Website | Copyright Notice | Visitors' Book | Contact Us | What's New The Burren: Limestone Pavements, Clints and Grykes As the ice-cap moved into the Burren from the north-east it carried with it some debris, such as the granite boulders (Glacial erratics) on the coast line. However, the main action of the glacier was to scour the rock clean off any superficial cover that formerly may have lain on the surface, thus exposing and smoothly polishing the underlying bedrock which we know today as the largest classic karst limestone pavements in these islands. Pavements are made up of two separate but integral parts known as clints and grykes. Clints are the blocks of limestone that constitute the paving, their area and shape is directly dependant upon the frequency and pattern of grykes.

Grykes are the fissures that isolate the individual clints. The most dominant gryke system runs almost north to south and there is a secondary less-developed system at right angles to it. Grykes can stretch for hundreds of feet until they suddenly terminate or are lost beneath superficial deposits. Grykes are usually straight but are occasionally curvilinear. Burren Flagstone Water is the dynamic of the Burren, water created it, and water is destroying it. This destruction can be seen in some of the clints where the water draining from the horizontal top is cutting deep channels or runnels into the shoulders of the clint, thus directing the water into the gryke where it will eventually widen the gryke and undermine the clint itself. On some clint tops one will see small saucer shaped depressions or shallow pans. These pools hold water, and can hold a layer of organic material, which includes algae called Nostoc. This algae exudes a mild acid which further breaks down the limestones, and so an even larger depression is formed which will eventually hold a colony of soil capable of sustaining a disparate assemblage of plants and grasses.

BBC - Higher Bitesize Geography - Rural land resources : Revision, Page2 Next Limestone pavements and swallow holes The Pennines is the backbone of Northern England, running from Northumberland in the north to Derbyshire in the south. It's also one of the areas in the United Kingdom where upland limestone scenery is found. In the North Pennines this type of scenery is found in the Yorkshire Dales, and in the South Pennines the Peak District is well known. Both these areas are National Parks because of their beautiful scenery, range of wildlife and local history. The examples we're using in this bite are from the Yorkshire Dales National Park. If carboniferous limestone is capped by impermeable rock, surface streams can run on to limestone. However, this water disappears from the surface, either by seeping through joints in the limestone or as streams disappearing down through swallow holes. It is the action of water which is responsible for many of the distinctive features of upland limestone scenery. When you study upland limestone scenery remember you should describe and explain both surface and underground features. Surface features include limestone pavements, dry valleys, gorges and scars. Underground features include caverns, potholes, stalactites and stalagmites.

Limestone pavement, near Malham Carboniferous limestone is made of blocks of rock. The clear horizontal lines are called planes and the vertical cracks are called joints. The rock is permeable which means water can pass through the lines of weakness - the bedding planes and joints. Rainwater is a weak carbonic acid which reacts with the limestone as it passes through the rock. It dissolves the stone, enlarging joints and bedding planes. On the surface the chemical weathering widens and deepens cracks to form grykes. This leaves exposed blocks of limestone called clints and the resulting pattern of blocky rock is called a limestone pavement. Chemical weathering of limestone pavement The chemical weathering is shown by the formula: CaCO3 + H2CO3→Ca(HCO3)2 (limestone + carbonic acid →calcium hydrogen carbonate solution) Shakeholes and potholes Occasionally, hollows are created on the surface of limestone. They form where drift material falls into joints which have been enlarged and widened by chemical solution. The hollows are called dolines or shakeholes. The shakehole is then eroded by streams and a vertical hole known as a pothole or swallow hole is formed.

These holes can, in turn, be enlarged by heavy rainfall or glacial meltwater. Gaping Gill, in the Yorkshire Dales, is an example of an enlarged swallow hole. Page This site uses the Yorkshire Dales National Park as a case study to explore both the physical and social geography of an upland limestone area. Links Visit this rich site dedicated to the features and processes that make up Scotland's North East coast. Audio Try something different - download this Audio Bite (mp3). You can also download the transcript too (pdf, 32.4 kB). Links Discover changing physical and human landscapes across Scotland Links Jimmie MacGregor goes on a tour of the southern uplands Links View and share maps online, and much more. Check out the 3-D animated fly-throughs. On the web Clints - definition of clints by The Free Dictionary Clints - definition of clints by The Free Dictionary Related to clints: grykes , grikes clint (klɪnt) n 1. (Geological Science) a section of a limestone pavement separated from adjacent sections by solution fissures. See grike 2.

(Physical Geography) any small surface exposure of hard or flinty rock, as on a hillside or in a stream bed [C12: from Danish and Swedish klint, from Old Swedish klinter, related to Icelandic klettr rock] Want to thank TFD for its existence? Tell a friend about us , add a link to this page, or visit the webmaster's page for free fun content . Link to this page: Copyright © 2003-2017 Farlex, Inc Disclaimer All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional.

The Burren; karst landscape; limestone pavements; grikes; clints; alpine flowers; Poulnabrone Dolmen; Ecclesiastics 3:11; Isaiah 61:3 | Summer Setting Posted on May 8, 2012 | 2 comments “The Burren” stands in stark contrast to the lush countryside dotted with sheep and edged with golden gorse that greeted us along the way. The Burren means “great rock,” and it it internationally famous both for its remarkable glacial-karst landscape, which is one of the finest in the world, and its almost unique floral ecosystem that supports alpine, arctic, and Mediterranean plants side by side. It covers a huge area (about 100 square miles) in northwest County Clare, Ireland, although the national park proper is only 15 square miles.

The rolling hills of the burren are composed of limestone pavements where layers of rock have dissolved due to the presence and action of glaciers (thousands of years previous) leaving crisscrossing cracks known as “grikes,” and isolated rocks called “clints.” This solutional erosion causes the geological formation known as “karst.” The unique combination of year-round moderate temperatures, protected surfaces, and subterranean drainage allow an amazing variety of plants to grow! Delicate alpine flowers bloom side by side with plants common to temperate zones! Statistically, late May is the sunniest and best time of year to see the fireworks of gentians and avens, but early May was beautiful too! Everywhere little treasures were eking out an existence among the rocks! Some I recognized—like the wild roses and ivy— But, some I could not name. There are many ancient sites in the Burren, such as this castle ruin, and there are over 90 megalithic tombs! The most famous is the Poulnabrone Dolmen.

Michael and Grace, who preceded us to Ireland, said this was probably Mike’s favorite stone table and a “must see,” although he warned us that it would be hard to find. In fact, for some of the sites in Ireland, the best way to find them is to look up (ahead of time) lines of latitude and longitude for your GPS, since it’s not always possible to find anyone to stop and ask as you’re driving through great stretches of wilderness with no road signs to hint at where you should be going. 🙂 The Poulnabrone Dolmen is immense! It has a 30-foot chamber in the low cairn, and the gigantic capstone slab is thought to weigh 3,300 pounds! “Poulnabrone” means “hole of sorrows,” and when it was excavated, the bones of nearly 30 adults and children were found, including one newborn. We made our way to our B’n’B through the gathering gloom of rain followed by a peaceful sunset in gold and cerulean pastels. I almost felt like God was reminding me of Isaiah 61:3.

He brings beauty out of bareness…He will “give unto them beauty for ashes, the oil of joy for mourning, the garment of praise for the spirit of heaviness; they that might be called trees of righteousness, the planting of the LORD, that he might be glorified.” “He has made everything beautiful in his time” (Ecclesiastes 3:11).

Question: Clints and grikes are found in formations of which rock?
Answer: Limestone