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 …

In other words, this is a place to visit time and again, at different times, in different ways. Each time the experience will be different.

Starting off

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.

From here continue down the road and enter the wood at the south-east corner and follow the trail markers up onto the esker ridge to the first stop. (As you make your way down the road you will see some fine spindle bushes on your right hand side: they will be much more obvious in autumn when they have their unmistakable cardinal’s-hat fruits.

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, and they vary considerably in height and breadth. They are exceptionally well developed in Fennoscandia, Maine and across the Canadian Shield, 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. The flora and fauna of these areas is especially diverse, and include several species of special conservation interest. Both marshes occupy hollows in the esker network, but the upper one was drained in the 19th century and is drier than it once was. 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’s-tongue, 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! But there are a number of places where the forest tracks cut into the esker and let you see what they are made of. 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, which is perhaps best appreciated in spring, before the tree canopy closes over and limits the amount of light reaching the woodland floor. 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 (mainly April to June). 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 Woodbank

At this point you can see one of the ancient enclosure banks that are found in several areas of the wood; this aspect of its history is one of the things we hope will be studied more carefully in the years ahead. 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 pre-date 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. Coillte has 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 the Irish flora. Lianas are woody climbing vines, more typical of rain forests than temperate woodland. You won’t see much of the plant here though because it’s away up in the canopy where most of the light is, but if you keep an eye out you will see it in lots of other places in Knockbarron.

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.

Downloads

Knockbarron EcoWalk Downloadable Map