The Burren
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The Burren |
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| The north-west corner of Co.Clare is one of the most interesting and striking landscapes in Europe. It is an area of naked sheets of limestone running into the sea as low cliffs on rocky shorelines , and re-appears as the three Aran Islands at the mouth of Galway Bay. The Burren is interesting from the points of view of geology , archaeology , and botany , as well as being strikingly beautiful in it's bareness. The Cromwellian general who remarked that there was not a tree on which to hang a man , or enough water to drown him , or enough soil to bury him , was in fact catching the 'feel' of the Burren in a sentence. |
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| Modern visitors are less bloodthirsty , and come for the walking , sea-angling , photography and caving that make this corner of Ireland such an attraction. There is so much to the Burren that it could easily sustain a web-site all to itself. ( Ed. note : Since this page was written , I have in fact discovered a lovely little website dedicated to the Burren and surrounding areas , written by a San Francisco lady ; Mary Comber who states home-sickness to be part of her motivation , check it out at www.hooked.net/users/comber/ ) | |
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A karst landscape is a limestone region which
exhibits many different natural rock features, most of which are due to chemical and physical weathering
and the process of denudation. Denudation is the removal of soils and vegetation from the rock surface leaving large sheets of bare rock. The limestone present in this karst region is carboniferous limestone. This type of limestone consists essentially of calcium carbonate. |
The bedding planes and joints make the rock very vulnerable to weathering as the rock is pervious , and because of this , water can seep through the joints and bedding planes. As limestone is essentially composed of calcium carbonate , and as calcium carbonate is soluble , it is vulnerable to a chemical weathering process known as carbonation. In this process rainwater absorbs carbon dioxide from the atmosphere and thus forms carbonic acid. This acid reacts with the calcium carbonate in the limestone and converts the calcium carbonate into calcium bicarbonate which is removed in the solution , causing erosion. (Other cause of chemical erosion would be by acidic rain or organic life in soils , if present.) The water that carries the calcium bicarbonate seeps and percolates underground and the carbonation process is renewed. When evaporation occurs , calcium carbonate is deposited on the walls and ceilings of underground caverns or caves which themselves are created by carbonation and roof collapse , resulting in features such as stalagmites , stalagtites , dripstones and pillars occuring.
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There are many features of karst landscapes. These are above ground features and underground features.
As we know limestone is attacked by the process of carbonation. Where joints reach the surface they are widened and deepened by carbonation , to form deep furrows known as grikes. These grikes divide large sheets of limestone into disected rectangular - shaped slabs known as clints. The combination of both clints and grikes is known as Limestone Pavements. As time progresses these widen and deepen , many reaching several metres in depth. A thin layer of soil usually develops and gathers in the grike which is often home to various unusual plants and flowers , such as the Wild Orchid. Visible evidence of carbonation would be small hollows on the clints.
Other above-ground features or surface features in the Burren are swallow-holes , also known as sink-holes. A swallow-hole is an opening in the bed of a river which flows over limestone. At this hole or opening the river takes its course underground and proceeds to wind its way under the surface. Swallow-holes may be several metres in diameter and over one hundred metres deep , however in the Burren swallow-holes present are not very deep. Rivers that disappear in this manner , through swallow-holes may re-appear further down slope or further down its course as a spring. Waters such as these are not true springs as their water has not been filtered through bedrock. Examples of swallow-holes in the Burren are Poll na gColm or Poll Eilbhe.
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Underground features in the Burren are Caverns and caves. Features of these caverns or caves are stalagmites and stalagtites.
Caverns are formed by underground streams which act upon fissures , thereby enlarging them. Eventually huge underground passageways form. Some caverns may even be as big as cathedrals. It is from this that some caverns get their name.
Stalagmites and stalagtites are formed by carbonation (the process by which limestone erodes). Deposits of calcium carbonate on the roof and floors of these caverns results in stalagmites (develop on floors of caverns) and stalagtites (develop on roof of a cavern). All these subterranean features are visible in the Ailwee Cave which has been developed for visitor access.
This part of Ireland , being in the Western Seaboard , has a mild , damp climate; there is rainfall throughout the year. In addition the West of Ireland is windy , and the ocean winds carry flecks of spray ; this leads in places to the development of halophytic vegetation (owing its presence to the effects of salt spray. The natural tree limit is almost at sea-level (because of both the landforms and the strong prevailiing winds ) on the exposed areas , but scrub (mostly hazel ) will grow in sheltered hollows , and actual trees can be found in sheltered valleys away from the coast. In the Burren plant specimens of Alpine , American and Western Mediterranean types can be found vitually side by side. ( Warning ! This is a natural park , all species of plant and animal life are protected , and their removal is an offence. In addition , these plants have become so location-specific that they invariably fail when transplanted elsewhere. So please do not attempt to collect them.) Such alpines as gentian verna and dryas can be found growing in the top of the pavement with such Mediterranean imports as maidenhair ferns in the cracks beside them. Hazels and hawthorns predominate in the scrub , along with ivy , blackthorns , spindle bushes, birch , ash , holly , elm and scotch rose ; few of these will exceed 10 ft (3m) in height , because of the strong winds. It is interesting to note that there is rich grazing land in the valleys around Ballyvaughan because these valleys are aligned north-south , whereas valleys aligned to the west are bare of vegetation other than in the cracks and fissures.
To see a larger listing of flora to be found in County Clare click here.