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Glenafelly EcoWalk

Glenafelly is one of the dozen or so glens that radiate out from Slieve Bloom like the spokes of a wheel.

Most of the valley is covered with glacial deposits, so that the underlying bedrock is seldom seen – except where the Glenafelly stream and its tributaries have cut deeply to the base of the till, and sometimes along the sides of the glen.

Four valleys meet at the mouth of Glenafelly: the valley you walked or drove along on your way from Kinnitty, a second wide valley that runs to the north-east, at the foot of Knocknaman, the river-carved valley of Glenafelly itself – and the narrow, wooded gash in the hills through which the road runs south of the car park. This is the Tulla Gap. Unlike Glenafelly, it is not a river valley. It is a glacial spillway.

At the end of the last Ice Age, as the great ice sheet that covered the south midlands began its retreat northwards away from Slieve Bloom, a lake network existed in front of the glacier for a time, impounded between the ice front and the barrier of Slieve Bloom. Sand, gravel and silt were washed by glacial meltwater into this lake, there to be sorted into distinct layers of different grade. These kame moraines are a main source of sand and gravel; you will get a good look at what they are like on the inside at Stop 1.

In time, the water of this lake found a way out to the south through an opening in the hills. Once this little breach was made, the force of the water behind swelled what was initially a gentle flow to a torrent that tore its way through the gap, gouging it more deeply in the process, and leaving a great blanket of sandy sediment behind in the abandoned lake bed.

This glacial legacy had a profound influence on the human story. In earlier times the gap provided a convenient route for the road running south from Kinnitty in the direction of Roscrea. Strategically placed forts overlooked the route from several of the surrounding hills (we will visit one at Stop 2), and there are several ring barrows (prehistoric burial mounds) adjacent.

At the junction of the four valleys a great stone of quartzite was erected in prehistoric time. This is the Fiddler’s Rock you see in the field across the road from the car park. The best viewing point is from the picnic site at Stop 1. The significance of this special stone for the ancient people who erected it is explained later, where you can see how it relates to the surrounding valleys at Stop 9.

As you will be able to see for yourself, the deep blanket of lime-rich glacial sediment that covers the open area at the mouth of the valley (Stop 1) is very different from the more locally-derived glacial till you see further up the glen (Stop 4). It is sandy and lime-rich, and makes better farmland. It is also full of limestone cobbles and boulders brought into Slieve Bloom from the Carboniferous Limestone country that surrounds the mountains. These were quarried and burnt in lime kilns to make lime, which could then be applied to the lime-poor soils further up the mountain. They played a critical role in the farming of an earlier age. You can see a very fine example of one of these lime kilns later at Stop 9.

Because of its varied topography and geological circumstances, Glenafelly is a biologically diverse area, full of ecological interest. A hundred different niches for wild creatures exist, and there is always something new, something different. Nearly a hundred and fifty species of flowering plants have been recorded (see the species list).

Milestones on a walk of discovery

Glenafelly Map Click for larger view

Stop 1

Standing stoneThis is an old sand and gravel pit where you can view the interior of the moraine. Notice the way it is sorted into distinct layers, not all jumbled up. This only happens where you have water to sieve it into the different grain sizes. The fact that many of the layers are very fine-grained (silt or clay) tells us that the water at these times was very still.

This is also an ideal viewing point for the standing stone in the field to the north. It has never been excavated by archaeologists so we cannot say for sure how long it has been here, but it has probably stood here for thousands of years. Later on we will try to explain what its function may have been.

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Stop 2

Ringforts were the farmsteads of early Christian Ireland. However, this fort overlooking the Tulla Gap probably exercised a strategic function; an ordinary ringfort would not have been located immediately on top of such a steep slope. Notice the way the stream flows around the ditch surrounding the fort.

The fort is closely hedged about with Sitka spruce at present, but over the next few years these will be cleared to restore something of the splendid view the fort enjoyed in its heyday.

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Stop 3

Glenafelly Stream


Plant life in Glenafelly
Some 150 species of flowering plants and ferns can be found in Glenafelly: and there is something of interest to see and admire at every season. You will find a full list here.

Foxglove is perhaps the most attractive plant to be seen in Glenafelly, abundant especially in the first leg of the track, and at its best in late June and early July when in full flower. In April and May and on into June bluebells are in flower, and are very frequent along the first stretch of the track.

Many of the common – and some less common – grass species grow along the road; this is a good place to become acquainted with grasses and indeed with the flora to be encountered generally along forest rides. One of the less common species is early hair grass, which one hardly notices at first, until it is pointed out. It flowers early, but is perhaps most conspicuous around July when the stems turn red as the seeds ripen.

The most conspicuous plants in the flora of Glenafelly are flowering plants, but where the track is closely shaded by the spruce trees there is a very luxuriant bryophyte flora. Bryophytes comprise two groups of plants: mosses and liverworts. Both groups are very species-rich, but because they are nearly all small, green plants – some of them very small, they are not readily noticed: and they lack the flowers of such varied hue and design that make it easy for us to distinguish flowering plants from each other.

They are most luxuriantly developed by the sides of the track in the upper part of the glen, where there is more shade and conditions are wetter. The most eye-catching include several kinds of bog-moss species (members of the genus Sphagnum). Carpets of thread mosses (Polytrichum and Pogonatum species) form extensive cushions resembling miniature pine forests. A Polytrichum cushion can be extensive, and the individual moss plants in it as long as a metre; Pogonatum plants are very much smaller. One particularly attractive moss species that is common on the road cuttings but does not form the eye-catching cushions of Sphagnum or Polytrichum is Rhytidiadelphus loreus. Lots of other species grow in the forest itself. There is enough interest in the moss flora of Glenafelly to merit a lifetime of study. They are plants of enormous beauty and fascination, but it does require the extended eyes of the hand lens or microscope to fully appreciate their diversity, complexity and beauty.

There are two sorts of liverworts, thallose and leafy. Thallose liverworts look a bit like diminutive seaweeds. The most conspicuous species in Glenafelly is called Pellia epiphylla. It can be seen in many places, most prominently perhaps alongside the roadside cutting after the sharp bend in the road, approaching Stop 4. Leafy liverworts are tiny plants, and you really do need a hand lens to appreciate them at all well. But they can be very abundant where conditions suit them. You will notice for example in the upper part of Glenafelly where the track is shaded it is covered with what looks like a green film. This is a forest of the liverwort Scapania undulata, and there are several other common but less prominent species along with it.

Along the track you will often see patches of the dog lichen Peltigera, looking like little seaweeds, but grey, greenish or slaty in colour. At certain times of the year the margins develop conspicuous brown tooth-like structures; these are the spore-producing organs. In earlier times it was thought the appearance of a plant provided clues as to what curative properties it had. The resemblance of the spore-producing areas on dog lichen to teeth was taken as a sign that it was an effective treatment for rabies.

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Stop 4

Rock Exposure

At a number of locations along the walk you get a glimpse of the rocks that prevail over most of the valley – but they are not often seen away from the river. The small excavation at the side of the track at this stop gives you a first glimpse of the bedrock that underlies the blanket of glacial till.

The rock you see here is a mixture of a special kind of sandstone called greywacke and finer-grained siltstone. These rocks originated as sediment washed into the deep ocean that covered what is now Central Ireland in the middle of the Silurian period of earth history, 425 million years ago. At this time, our little bit of the earth’s crust lay far south of the equator. The sedimentary sequence of which this is a tiny part is described as a turbidite. Vast accumulations of sediment build up on the continental shelf adjacent to the mouths of the earth’s great rivers. In time this ever-growing lobe of sediment becomes unstable and it begins to move under gravity, gathering speed as it does so, and an enormous slurry of water and sediment rushes down a submarine canyon cut into the edge of the continental shelf, out into the ocean, where it eventually settles out as a submarine fan in very deep water. The silt of which this block of rock is composed was part of one such flow in Silurian times. These Silurian rocks are the oldest found in the midlands.

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Stop 5

Glacial Sediment

The apron of glacial sediment reaches far into the mouth of the glen, but it does not extend all the way up. As you walk up the track you will see the way the river cuts its way through it. The rocky debris which covers the bedrock in the upper part of the glen is predominantly of local origin and largely the result of frost action at the end of the Ice Age. You can see it in many places along the track. Over thousands of years weathering has removed the clay matrix and the solid rock eventually ends up at the bottom of the glen. This is the rock that you see in the stream bed.

FordJust before fording the stream at this point notice the till section on your right. This is a good example of the local till. You will notice that there are two distinct layers in it here.

Along the track between Stops 5 and 6 is a good place to look out for one of the rarer plants of Slieve Bloom. This is trailing St. John’s-wort Hypericum humifusum. It is rather shy, so you need to look carefully, and you are only likely to spot it when it is in flower between July and September. There are two species of St John’s-wort here, both characteristic of heathy places: elegant St John’s-wort Hypericum pulchrum (very common in Glenafelly), and this less frequent trailing St John’s-wort.

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Stop 6

Along this stretch of the walk the rock that overlies the Silurian in Slieve Bloom appears at the surface. This is sandstone belonging to the Old Red Sandstone series. It was laid down in the bed of an ancient river at the very end of the Devonian period of earth history around 354 million years ago. It is never well exposed here in Glenafelly, but you can see splendid exposures on two other Slieve Bloom EcoWalks, on the Silver River and in Glenbarrow.

There are also excellent sections along here through the blanket peat that overelies the glacial till everywhere on the higher ground in Slieve Bloom. Even more extensive profiles can be seen on the Gorteenameale EcoWalk.

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Stop 7

Here you see all that remains of a typical 19th century Slieve Bloom farmstead. At this time of population expansion settlement in the mountains pushed right up to the head of the glens, and the land here was farmed right to the head of the valley. Life here was hash and frugal, but the setting was idyllic. It is hard to find words for the beauty of this location, or to appreciate the way it nestles into the head of the valley out of the wind.

The farmstead is lost in Sitka spruce at present, but over the next few years these will be cleared to allow visitors to appreciate the splendour of the location.

Keep an eye out for New Zealand willowherb on your way between this and the next stop. Of the four willowherb species that occur in Glenafelly this is perhaps the most interesting. As its name informs us, it has come to us from the opposite end of the earth and has been here little more than a century: but unlike so many aliens it has not had a disrupting influence on the native flora, occupying as it does bare ground that was little occupied before.

Normally you only see the upper side of the leaves, but look at the under side, which is often a glorious red. It is often especially conspicuous after it sets seed, when the trailing network of ribbons of small leaves turns an attractive salmon colour.

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Stop 8

Caledonian orogeny

At this small quarry we encounter the Silurian rocks again. But at this location if you look carefully you will see the rocks are inclined at a steep angle. The originally horizontal rocks were upheaved during a mountain building episode known as the Caledonian Orogeny at the end of the Silurian period. The great mountain chain of which these folded rocks were a tiny part was comparable to the Himalayas of today. By the end of the Devonian period the forces of erosion had worn them down to next to nothing, and it was across this leveled landscape that the rivers in which the Old Red Sandstone was laid down flowed.

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Stop 9

Lime kiln

As you come down the track you have an excellent view of the situation of the Cumber Gap and Fiddler’s Rock in relation to the surrounding landscape. If you look into the field beside the track you will see a number of sandstone boulders some way down the field. These mark the location of a lime kiln of unusual construction. Lime was the key ingredient in the reclamation of these hills for agriculture in the 19th century. It neutralized the acid peat and along with drainage and much hard work made their cultivation possible. If you look carefully you can still see the cultivation ridges from that time, especially in winter when the slight parallel corrugations of the ridges are highlighted by the low sun.

The Fiddler’s Rock is located in a sort of amphitheatre between the hills, where several valleys meet. The stream that flows by the Rock emerges from Glenafelly on the east and then turns to flow north when it meets the obstruction of Cumber Hill a little way past the Rock. Another broad valley runs between Carroll’s Hill and Knocknaman, and the Tulla Gap, at whose mouth the Fiddler’s Rock stands; this is a much narrower but more conspicuous valley. Much of this amphitheatre is floored with gravelly glacial debris that shows evidence of having been sorted into layers of different coarseness in still water

The Glenafelly stream has cut its way through the moraine at the foot of Cumber Hill. The road from Kinnitty to Glenafelly makes its way along the eroded edge of this apron of sediment.

The Fiddler’s Rock, whose situation in the surrounding landscape you can better appreciate from this viewpoint, is one of the most tantalizing of the monuments from the past in Slieve Bloom. It is made of quartzite. It seems to be aligned with certain other monuments, but that might be coincidence, and in any case the stone still remains cold and silent. There are no whispers here that might bring to life the men and women who, for whatever reason, placed it here. There are no footprints to follow, no echoes of distant singing carried in the wind.

But if you happen to be here on a sunny day in the middle of winter you will catch a glimpse of its meaning. At that time of year late in the afternoon a great beam of sunlight streams through the glacial spillway of the Cumber Gap, across the Fiddler’s Rock, whose long shadow points like a dark finger in the direction of Knocknaman, sending its rays reassuringly into the valley below.

For prehistoric people the sight must have lifted the darkness out of the heart of winter with bright assurance of the sun’s imminent turning and the sure return of spring. And if it can strike even our 21st century spirit like this, what must it have been for the Bronze Age Kinnitty folk who placed it so carefully here to mark their bond with earth and sky? Finding the heartbeat behind the stone, behind all that remains, is what archaeology is really all about.

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Stop 10

River

Notice that the stream bed is dominated by large stones from the glacial till, most of them Silurian rock. All the finer sediment has been swept downstream. This rock is important in an ecological sense because it provides shelter for the abundant macroinvertebrates that live in the steam. If you turn over a stone in the stream you will see startled mayflies, stoneflies and caddis grubs scurrying about. These are what the small trout in the steam feed on, as well as the stream’s resident dippers.

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e-mail info@slievebloom.ie    Telephone +353 86 2789147    Fax + 353 05791 37299

 

End

QUICK LINK
to Eco-Walks

Eco-Walks Home Page


1  Glenbarrow

2  Knockbarron

3  Glenafelly
    Stop 1    Gravel pit
    Stop 2    Ringfort
    Stop 3    The Glenafelly stream
    Stop 4    Rock exposure
    Stop 5    Ford
    Stop 6    Old Red Sandstone
    Stop 7    Farmstead
    Stop 8    Caledonian orogeny
    Stop 9    Lime kiln
    Stop 10   Life on the river

4  Silver River

5  Gorteenameale

Plant and Animal life in Glenafelly

 

Slieve Bloom Eco Walks

DETAILS

Type: Eco Walk Loop

Trailhead : Start/Finish Glenafelly Car Park 3k from Kinnitty Co Offaly

Distance: 7K

Time : 2 Hours

Ascent: 60 Metres

Difficulty: Moderate

Terrain: Forest tracks riverside paths

To Suit: Good level of fitness

Minimum Gear : Sturdy Walking Boots, Rain Wear, Fluids, Mobile Phone.