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Limestone Country: The Burren


A thick blanket of fog covers the wintery landscape. The path, carved by countless feet into the shallow layer of dirt that covers the limestone, is barely visible. The damp air is swirling around me, at times lifting for the blink of an eye to allow a brief glance of wet limestone slabs and the vague outline of shrubs. Suddenly the lake emerges out of the grey wall of mist, its surface motionless, its extent hidden. It is winter solstice day, and even though it is almost lunchtime, it feels like early morning. I am on my way to the summit of Mullach Mór, the iconic, flat-topped hill that sits in the heart of the Burren National Park, a limestone karst area that has mesmerised visitors and locals for millennia.

I am losing sight of the lake, but the stile in a dry-stone wall shows me that I am on the right track. A few steps further and another waymark, a small stand of hazel, becomes just about visible to my left. Soon after, a number of natural steps in the limestone bring me onto the first plateau of Mullach Mór.

Any landmarks and way markers are now completely hidden in the fog, which is thicker than ever. The path has disappeared, and the limestone at my feet doesn’t keep any memories of previous travellers. I am stranded, and all I can do is sit and wait. Time goes by, the cold and damp slowly making its way through layers of clothing.

Then, all of a sudden, it seems to be getting brighter. I can see a bit further; the curtain is lifting enough to wander on. Patches of blue appear in the sky above me, and the mountainscape of the Burren is revealing itself all around: Poulnalour and Slievenaglasha to my left, Slieve Roe and Knockanes ahead of me, and the lowlands of Clare and Galway to my right. The skeletons of the hazel scrubs glow in gentle brown and yellow tones, the wet limestone is glistening in the light, and the only sound is the hushing of the wind. This is the Burren.  


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Most of Ireland’s bedrock is made from limestone, but only in a few places has this rock come to the surface to become the landscape. It does so in counties Fermanagh and Cavan and a few odd spots in the midlands, but Ireland’s ultimate limestone landscape, the Burren, lies in the northern half of County Clare and spills over into southern County Galway. The first impression of this area is one of gloomy desolation. From a distance, the first features to catch the eye are terraced, raggy and seemingly bare hills. A closer look reveals polished rock pavements that are traversed by deep fissures and strewn with rocks known as erratics.

On dry, sunny days, the rock presents itself in a bright, almost blinding, grey. After a downpour, the landscape changes to a dark grey, almost black, and glimmers with a blueish tint. And on those soft days that are so typical for Ireland, when a constant fine drizzle drenches the land, it is almost impossible to tell where the dark, grey landscape of the Burren ends and the sky begins.

The name derives from the Irish word ‘boireann’, meaning ‘large rock’ or ‘rocky district’. The English politician and military leader General Edmund Ludlow, while passing through on a military campaign in 1659, described the Burren as ‘a country where there is not enough water to drown a man, wood enough to hang one, nor earth enough to bury him’. In the following centuries, the Burren has been described variously as a moonscape and a fertile rock; songwriter Luka Bloom sang about the ‘flowering desert’, and for botanist Charles Nelson, the Burren was a ‘limestone wilderness’. Whatever you would like to call it, the Burren is a landscape that catches the imagination; it is cherished and respected by its people and known to leave a deep impact on its visitors. The Burren seems to exist on another plane, not quite part of the real world, timeless in one way but also laden with the burden of history. There just is no other place like it.


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The Burren is a limestone karst landscape. Its foundations were laid down during the lower carboniferous period some 350 million years ago, far away from its current location on the west coast of Ireland. Imagine a shallow ocean in a tropical climate just south of the equator. Some of the inhabitants of this ocean were the ancestors of our snails, mussels and corrals, all of which shared one feature: a shell made of the minerals calcite and aragonite. Once the inhabitants of these shells met their end, the shells sank to the seafloor. There, they accumulated, layer after layer, and over a period of some 20 million years, they hardened into limestone, which eventually reached a thickness of up to eight hundred metres. Periodic outwashes of mud, sand and clay from adjacent river estuaries added bands of shale and other deposits that in places separated the limestone beds. During the upper carboniferous period, these fluvial outwashes became more dominant, and as a result shale and sandstone built up over the limestone and, in time, completely covered the older rock.

Time passed, continents moved, and Ireland took its current place on the map. The earth’s climate oscillated, cooling and warming in cycles. The colder periods saw vast glaciers advancing from the poles, covering much of Europe, including Ireland and the area of the future Burren. Once the temperatures started to rise, the ice would retreat northward for a while, releasing the land from its icy grip. This process went on for thousands of years, and the back and forth and back again movement of these immense masses of ice, several hundred metres thick and weighing many tons, sculpted the landscape. In some places the glaciers cut deep valleys in the rock; in the Burren, they completely removed the top layers of shale and sandstone, exposing some 250 square kilometres of the underlaying limestone. The best place to see the transition from limestone to shale and sandstone is to the south-east of Doolin Harbour. Here, the limestone disappears under the sandstone cliffs that rise further south to form the Cliffs of Moher.

The glaciers carried vast amounts of rock, gravel, sand and silt with them. Once the temperatures rose and the ice began to melt, this luggage was dropped on the landscape. Drumlins – small, elongated hills of silt, gravel and rocks – are a common sight all over Ireland. In the Burren, drumlins mainly appear along the southern and eastern borders. Erratics, however – from the Latin errare, to wander – are obvious all over the Burren, from the coast to the mountaintops. Most of these wandering rocks are made of limestone, but sandstone and granite erratics, which originated further north in Connemara and were transported by the glaciers to their current resting place, can also be found.


The bleak landscape of the Burren that we see today is not an entirely natural phenomenon. After the end of the last glaciation, about 10,000 years ago, the Burren didn’t look very much different than the rest of Ireland at the time. After the ice had disappeared, a tundra-like landscape developed; with a warming climate, shrubs and trees established themselves and over time vast pine and oak forests took over the land.

It is possible that the limestone here never had a very deep soil cover and was more susceptible to erosion than other areas, but the first Burren farmers and the following generations certainly sped the erosion process along by clearing land for crops and livestock. The early settlers also left their mark on the landscape in other ways. The Burren has one of the highest concentrations of ancient monuments in Ireland, many dating back to the stone age. Cooking places known as fulachta fiadh, portal and wedge tombs, cairns, ring barrows and stone forts, early Christian monasteries, medieval tower-houses and the ubiquitous dry-stone walls are by no means natural but have all become an integral part of the Burren landscape.

Another factor that had significant influence on the juvenile Burren, even before the arrival of man, was water. Rainwater contains liquified carbon dioxide, which makes it slightly acidic; this acidic solution converts the calcite in the limestone into calcium bicarbonate, which dissolves in the water and is washed away. It is this process that shaped and sculpted the Burren to its unique appearance: smooth limestone blocks, or ‘clints’, that are separated by deep fissures known as ‘scailps’ (from the Irish word for ‘fissure’ or ‘cleft’), as well as grykes, runnels and flutes, terraced hills, sinkholes and vast cave systems. To date, some sixty kilometres of cave passages have been explored, but the true extent of the Burren cave system is believed to be a multitude of that.

The exploration of this underworld brought some unexpected glimpses into the Burren’s past. At Ailwee Cave, one of the two show caves of the Burren, the skeleton of a brown bear was found and dated to be 10,400 years old. A bear patella, discovered in another cave, shows parallel cut marks that were likely caused by a stone knife some 12,500 years ago. The presence of a top predator like the brown bear and signs that it was hunted by men suggest that a diversified flora and fauna already existed in the Burren towards the end of the last glaciation, before the complete disappearance of the ice. The second show cave of the Burren, Poll-an-Ionain, today better known as the Doolin Cave, features the Great Stalactite. With a length of 7.3 metres, this is the biggest free-hanging stalactite in Europe.

Most of the Burren’s cave systems have been formed by streams and rivers. The majority of these water courses stay underground; the only stream that runs its complete course on the surface is the Caher River, which has its source beneath Slieve Elva and enters the sea at the Fanore beach after a rather short run of only seven kilometres. The upper part of the Caher is a gentle flow through hazel scrub and meadows, one of the most secluded and beautiful spots in the Burren. In the early 1990s, local man John MacNamara turned this area into a nature reserve. His goal was to let nature run its course and leave the plants and animals in this little kingdom undisturbed. I had the pleasure to know and work with John for a brief time, but unfortunately our plans to put together a photographic record of the plants and animals at the Caher Valley Nature Reserve were cut short. John passed away after a short illness in 2004. His hopes for the reserve, however, came true: after his death, the gates to the valley were closed, and the plants and animals were left in peace.

After leaving the Caher Valley Nature Reserve, the river turns west and starts to descend. Trout can often be seen swimming in the clear water, and it is not unusual to come across a dipper, otter or grey heron. On its last two kilometres before reaching the Atlantic Ocean, the Caher drops sixty metres and completely changes its attitude. The gentle river becomes a mountain stream and after heavy rain turns into a raging torrent, rushing around boulders and tumbling over cascades. Why the Caher River never wanders underground is not entirely clear, but it is known that in parts of the Burren, impervious layers of clay, chert and sandstone exist between the limestone. The most likely explanation, therefore, is that the Caher River runs above one or more of these layers, which prevents the water from going underground.

Some rivers make a sporadic appearance on the surface. The Rathborney River emerges from under Gleninagh Mountain, runs down the Feenagh Valley and disappears under the limestone once it has reached Ballyvaughan Valley. Castletown River appears in the Carron Basin, where it is the main source for the Carron Turlough, the largest of the Burren turloughs.

Turloughs are special water bodies that are unique to the Burren and other karst areas. They are often described as seasonal lakes since their existence is very much dependent on the prevalent precipitation. Unlike proper lakes, turloughs are not fed by a constant water supply like a river or groundwater. They are, however, connected to the cave systems of the Burren. During times of consistent or high rainfall, these underground passages flood and eventually overflow, filling the turloughs in the process. During dryer periods, mostly in spring and early summer, water levels fall and the turlough disappears.

All standing water bodies are restricted to the eastern Burren, an area known as the Burren wetlands. In addition to the turloughs, there are fens and lakes. Some are a combination of lake and turlough, so they never disappear completely but will easily triple in size during times of high rainfall. The most interesting of those is Lough Gealain. This lake is fed through springs under the limestone but also features a number of swallow holes that connect to the underground cave system. In autumn and winter, when rainfall amounts are usually higher, Lough Gealain expands considerably and at times floods the nearby road.


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Lough Gealain sits in the heart of the Burren National Park, an area that hosts all the major Burren habitats. In addition to the fens, lakes and turloughs, there are vast stretches of limestone pavement interspersed with patches of fertile soil, small woodlands and wildflower meadows. It is in these habitats where the famed Burren flora can be found. This wonderworld of wildflowers is rather unexpected in a place that on first sight appears to be made of barren and desolate rock. The Burren, however, hosts six hundred species of wildflower and other plants – seventy per cent of all species known in Ireland.

The most famous of the Burren flowers – and something of an emblem for the area – is the spring gentian. With its deep-blue flowers, this is an alpine   species which usually flourishes in the high mountains. In the Burren, it bursts into bloom around April and can be found not only at sea level but even right beside the sea. The coastal area of Ballyryan, north of Doolin, is, together with the Burren National Park, one of the strongholds of this enigmatic plant.

Each plant produces several hundred seeds, which are shed in summer for germination in the following spring. There is, however, one problem. In order to germinate, spring gentian seeds have to experience frost.  Although sub-zero temperatures are not unknown in the Burren, they are very rare, and years can go by between one frost event and the next. In order to survive, the Burren gentian came up with another solution: mature plants produce stolons (underground extensions of the stem)  , which grow new rosettes and subsequently produce new gentian flowers. After eight thousand years of isolation, the Burren gentian has not only developed this alternative reproduction method, it is also visually slightly different from the populations on the continent. For now, these differences are minute and only of interest to the keen botanist. But give it another few thousand years, and Gentiana verna might develop into a completely new species. 

Often found in the vicinity of this alpine beauty is the early purple orchid, a species more commonly at home in the Mediterranean. A little bit later in the year, the mountain avens, an Arctic   species, joins the mix and bursts into bloom beside the fragrant orchid, the pyramidal orchid, the red helleborine and the twayblade, to name but a few of the twenty-four species of orchid that call the Burren their home.

Another piece in the floral puzzle of the Burren is the presence of lime-loving (calcicoles) and lime-hating (calcifuges) plants, which are often growing in close proximity. Given the ubiquitous presence of limestone, it would be logical to conclude that the soil cover would consist of weathered limestone rock and the remains of glacial drift, a soil type known as rendzina. Calcifuges, however, wouldn’t thrive on such a soil. The existence of other soil types in the Burren was a bit of a mystery until microscopic examinations revealed the prevalence of an aeolian (wind deposited) soil known as loess. This loess most likely came from east Galway and Connemara and was deposited in various places all over the Burren during the tundra period, shortly after the last glaciation. Another theory is that sandstone and granite erratics that originated further north disintegrated over time to form loess.

Among the other floral oddities to be found here are O’Kelly’s spotted orchid, a white subspecies of the common spotted, and the pyramidal bugle, something of a stumped version of the common bugle. The latter is one of Ireland’s rarest plants and only flourishes in a few spots along the Burren coast, the Aran Islands (which are geologically a part of the Burren), in Connemara and reportedly on Rathlin Island, off the coast of Northern Ireland.

The question of why the Burren hosts these unusual and rare plants and plant communities has never really been answered. It is thought that the alpine and Arctic species arrived during or shortly after the last glaciation and were a feature of the early tundra-like landscape. After the climate had warmed enough, other plants, including the beloved orchids, followed from the south and settled beside the existing flora in the mild climate of Ireland’s west coast.


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The connection between human activity and the Burren flora became clear in the final decades of the last century. Back then, in order to protect the delicate wildflowers, it was decided to restrict farming activities in the area and considerably reduce the number of grazing animals. Surprisingly, this conservation effort had the exact opposite effect; because fast-growing grasses and shrubs, mainly hazel, blackthorn and hawthorn, were no longer kept in check by grazers, many of the delicate wildflowers were pushed out of their habitat.

Then, in the year 2010, the Burren Life project was founded, which aimed not only to find a balance between farming and conservation but to actually use farming as a conservation tool. The farmers who signed up for this project pledged to preserve the natural as well as the built heritage of the Burren by re-building dry stone walls, removing shrub and reintroducing traditional farming methods like winterage, where livestock are brought to upland pastures for the winter months. Today, the Burren Life project is a vital part of the conservation of the whole area. Without grazing animals, the diversity of the flora would be greatly diminished; in turn, the insect population would suffer, which would subsequently impact birds and mammals.

The Burren is a haven for insects. In addition to bees and bumblebees, dragonflies and damselflies, there are twenty-seven species of resident butterfly and well over two hundred species of moth. One of the latter, and a true Burren speciality, is the Burren Green. This moth was first recorded in 1949 and put the Burren on the map for Lepidoptera fans; it is the only place in Ireland or Great Britain where this emerald-green beauty has ever been seen.

One of the animals for which insects are a major food source is the bat. The Burren is an important stronghold for these flying mammals – all seven Irish bat species have been reported here, including the lesser horseshoe bat, which is already extinct in many parts of Europe.

Other insectivores are the viviparous lizard, which can often be found sunbathing on the warm limestone; the slow worm, which was introduced to the Burren in the 1970s; and the common frog, who looks slightly out of place hoping across the limestone pavement. The pine marten, whose varied diet includes birds, small mammals, insects, fruit and nuts, and its relative the stoat are the Burren’s top predators, while the feral goat is the largest of the wild animals. These descendants of once domesticated goats are not only pretty to look at, with their rugged and colourful appearance, but are also the only animal that munches on the ever-spreading shrubs, thereby playing their part in the conservation of the area.

Unlike other landscapes and habitats in Ireland, the future of the Burren karst and its famous flora is safe, for the moment at least. The combined efforts of farmers, communities and environmental groups make sure of this. The special case of the Burren, however, raises the more fundamental question of what conservation really means. Is it right to protect an admittedly unique but ultimately man-made piece of landscape – or would it be proper to let nature reign, which would transform the Burren into a very different landscape? Ungrazed, the Burren would quickly develop a hazel and ash woodland, a process that can already be observed at the foot of Mullach Mór and around Eagle’s Rock. In time, other trees, most likely oak and scots pine, would take over, and soil would build up and revert the Burren to its origins of a mixed woodland. Parts of the current Burren flora would survive in this new habitat; others, first and foremost the Arctic and alpine species, would probably disappear.

Ultimately, the Burren as it is today will only exist for a glimpse in the vast reign of time. In another few thousand years, the limestone will be gone, washed away into the ocean, or the Burren will have been decimated to a few small limestone islands by rising sea levels. Whichever way it may turn out, another of nature’s circles will have been completed.

Carsten Krieger, from "Wild Ireland"

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