The Knockbarron EcoWalk
In the woods at Knockbarron one of the finest and most intact esker systems to be found anywhere in Ireland is preserved. This tells the fascinating story of how these landforms came to be at the very end of the Last Ice Age.
This is also an area of old woodland with much of ecological interest at whatever time of year you visit. It is different at every season. Perhaps the best time for a first visit would be early May, when so much of the woodland floor is a bLue haze of bluebells.
In mid-summer the woods settle into a few months of dark contemplation, except for the marsh, which is now drier and from which the newts that visit in spring to breed have mostly departed, but where that retiring and magic little fern-reLative the adder’s-tongue, is beginning to show its tongues. If you are interested in fungi, autumn is a great time to walk through Knockbarron: and if your main interest is geological heritage the best time is winter, when the eskers are less obscured by vegetation. At this time there is nowhere the informed imagination can more easily conjure up the boom of melting glaciers or the thunder of their meltwaters…
Our walk starts at the entrance to the wood where the car park is. On your way along the road you will pass another entrance to the wood. A feature of speciaL interest here is the colony of solitary bees that inhabit the roadside bank at the edge of the wood. You might think these Little bees are allworking together the way honeybees do, but in fact each little bee is working for herself (yes, they are alLfemale). She makes a tunnel which she lines with special chemicals to keep it watertight, and at the end constructs brood cells in each of which she lays a singLe egg and provisions it with a sufficient suppLy of nectar and pollen. Then she seals the cell and starts another. The baby bee spends its childhood in this little brood chamber before pupating for the winter, and then makes its way out the following spring to continue the cycle.
Stop 1 – On Top of the Esker
Nowhere will you find a more spectacular example of a classical esker. The sand and gravel which they contain were the rock material which the glacier had picked up as it ground its slow way across the land, and were washed out as the ice melted. As these glacial streams were banked by walls of ice, their beds of sand and gravel were left as upstanding ridges when the ice melted. They formed at the very end of the glacial period, when extensive melting was taking place. The word esker (eiscir) is an Irish word - one of the very few terms bequeathed to the science of geology by the Irish language. Esker ridges can be as long as 500 km, but the eskers of the Irish Midlands are among the finest examples of Pleistocene eskers in Northern Europe, and are one of the most distinctive and unique features of the landscape of Central Ireland.
Stop 2 – The Marsh
There are two small areas of marsh at this end of the woods. A host of wetland plant species occurs here, including several species of sedges, marsh bedstraw, marsh willowherb, wild iris, skullcap, marsh pennywort and dozens of others. Perhaps the most interesting plant, though one of the least conspicuous, is the unprepossessing fern-relative adder’stongue, which occurs in an abundance equaled in few other places in the county. The marshes are an important breeding place for smooth newts. There is a wonderfully diverse invertebrate fauna, at its most conspicuous at the end of summer.
Stop 3 – Inside the Esker
So undisturbed is the esker system that you seldom have an opportunity to see what it is made of inside! Here where the track (the one that leads into the wood from where you saw the bees) cuts through it you can see the chaotic jumble of boulders, cobbles, gravel and coarse sand, all mixed up together, dumped by the turbulent meltwater in the ice tunnel in which the esker formed.
Stop 4 – The Blue Haze
Knockbarron has a diverse and interesting· flora and fauna. The most striking aspect of the flora is the profusion of bluebells that carpets large areas of the wood in spring. This reflects Knockbarron’s status as an ancient wood, because although it . has always been a managed wood, sections of it at least appear never to have been anything but woodland.
You can see bluebells along most of the walk when they are in flower. There are here all the time of course, but their flowering season is these few weeks at the beginning of summer before the canopy of leaves overhead closes and blocks off most of the light from the woodland floor.
Stop 5 – An Ancient Wood bank
At this point you can see one of the ancient enclosure banks. These may have been woodbanks, ancient enclosures constructed hundreds of years ago to keep animals from straying into managed forest. There is also the possibility that they predate the forest itself.
Stop 6 – Clearfell
Knockbarron Forest (or the Glen Wood as it is often known locally) came under state forest management around the 1940s. At that time a variety of trees were planted: Grand Fir, Scots Pine, Norway Spruce, Sitka Spruce and Beech. CoiLLtehas shown that it is possible to manage forest and land resources commercially while providing social and environmental benefits.
Stop 7 – Looking west
You have now crossed onto a different - and equally spectacular - esker that runs more or less in the same direction as the one you started on. As you walk along this stretch keep an eye out for the thick rope-like stems of wild clematis that climb into the canopy of the trees. Wild clematis (or old man’s beard as it is sometimes called) is the only true liana in I the Irish flora. Lianas are woody climbing vines, more typical of rain forests than temperate woodland.
Stop 8 – Knockbarron Oaks
In a number of areas in the woods you can find remnants of the oak that was more widespread in the Glen Wood when it was part of the estate of the Drought family (who lived at DroughtviLLe,just beside Knockbarron). These are young trees: but if you look carefully you will see that many have developed from shoots that sprouted when a much older ‘parent’ was felled.
Stop 9 – The High Point
The ridge is up to 20m high at some points. You may have noticed the way the esker rises and swells at intervals. Often it branches at these ‘beads,’ and there is often a change in the level at which the esker stands. These beads are thought to represent the end of a season’s deposition. The direction of branching gives us a clue as to the direction in which the torrential rivers in their ice-walled tunnels were flowing. Can you work out what this was for yourself?
Stop 10 – Gravel Exposure
This is another good place to see what the \ inside of the esker looks like (we saw it earlier at Stop 3). Look for the oak trees along the next stretch of the ridge. The network of forest tracks further diversifies the plant and animal life of the wood, because different species occur along these more permanently well-lit areas.