Fermoyle Loop Walk

Devonian Deposition

The story of Sneem begins around 390 million years ago. At this time Ireland was situated just south of the equator and existed as part of a large continent called Laurussia. Due to its position near the equator, Ireland was much hotter than today and the area that is now Sneem was dominated by an extensive floodplain with many river channels and lakes. This was a barren landscape very different from the green fields of today (grass would not appear for at least another 300 million years), but ferns, liverworts, mosses, and some early trees would have survived here. Large mountains in the north were being eroded at the time and vast amounts of sediments, such as silt, sand, and pebbles were transported by rivers and floods and deposited in the low-lying area that covered much of the Iveragh Peninsula. These sediments were not deposited in one event but gradually in layers over millions of years. Over time, as these layers built up, the weight of the overlying sediment compacted and solidified the grains to form solid rock.

The rocks around Sneem are distinctly purple and green siltstones and sandstones and belong to a group of rocks of similar age and composition found across Ireland and the northern hemisphere known as the Old Red Sandstone Formation.

Mountain Building

Leaving Sneem village, the incredible Dunkerron Mountain range rises to the north. The Dunkerron mountain belt stretches from Waterville in the west all the way to the Macguillycuddy’s Reeks to the east. The mountain building event that formed the Dunkerron Mountains is called the Variscan Orogeny and also formed mountains across Europe, Asia, and Northern America.

The Dunkerrons are monuments of a continental collision that occurred when Laurussia, the continental plate carrying Ireland, collided with the other continents of the time to form the supercontinent Pangea. During the continental collision, enormous amounts of compression forced rocks in the collisional zone to be pushed up, buckled, and folded into mountains. These mountains are composed of the Old Red Sandstones that were deposited during the Devonian Period. Across the mountains, the original flat-lying bedding layers of the Old Red Sandstones remain visible, although these have been overturned to unbelievable angles, a testament to the immensity of geologic forces. The uplift of the Dunkerrons was occurring at a maximum rate around 320 to 290 million years ago.

Throughout the loop, these striking mountains remain a central focus, with the highest peaks, Beann and Mullaghanattin becoming visible to the east and the lower hills of Slievenashaska and Coomnahorna revealing themselves to the west. 

Glaciation

By the Quaternary, our present geologic period, which began 2.6 million years ago, Ireland had completed its northward drift and obtained its present geographic position. Around this time the global climate began to oscillate between periods of warm and extreme cold. During the cold periods, large ice sheets covered much of Ireland. The glacial deposits and features of the Iveragh Peninsula mostly come from the most recent glacial period which was at its maximum extent around 25,000-20,000 years ago. At the time, much of southwest Ireland was occupied by an ice body that radiated outwards from a dispersal centre near the head of the Kenmare River. Ice from this centre spread out westwards across Sneem before continuing offshore into the Atlantic. While difficult to imagine, these ice sheets were likely over 500m thick and only the tallest mountain peaks would have protruded above the expansive icy waste.

These ice sheets had largely retreated from low ground by 14,000 years ago but not before ravaging the landscape and leaving behind the rugged terrain of Sneem today. 

Glacial Erosion

During the extreme cold periods, snow built up in existing hollows on mountainsides, and through continued accumulation, mountain glaciers formed. These mountain glaciers excavated wide and deep amphitheatre-shaped hollows in the sides of the mountains known as corries. Corries are extremely abundant and particularly stunning in the Dunkerron Mountains. Look out for the pyramidal peak of Mullaghanattin to the east of the Fermoyle Loop, which was formed by the excavation of corries on all sides of the mountain.

Many of the corries around Sneem contain lakes known as tarns. These lakes formed as the glaciers retreated and meltwater collected in the eroded hollows. These glacial lakes are best seen hiking through the Dunkerrons but keep an eye out for the Coomanaspig Waterfall on Knocknagantee which flows from the overlying Coomanaspig tarn down the steeply dipping back wall of Eagle Lough Corrie and is particularly impressive after heavy rainfall.

Glacial erosion was not restricted to the mountains but was also unimpeded in the lowlands of Sneem, where smoothed bumps and mounds of rock called roches moutonnée are found. These asymmetrical mounds have blunt quarried down-ice sides and more streamlined and gently sloping up-ice sides and formed as ice passed over the bedrock. Striations or grooves etched into the polished surfaces of these roches moutonnée were carved by pebbles and rocks embedded in the base of the glacier being dragged across the rock surface.

While perhaps not the most obvious connection given its current mild climate, Ireland was an important research region in early glacial studies. The language used to describe glacial features reflects this with terms frequently having roots in the Irish language. The word corrie is one of these examples, having its origins in the Irish work “coire” which means a large pot or cauldron.

Glacial Deposits

As the glaciers moved across the land they acted not only as an erosive force but also collected large amounts of debris that fell onto the surface of the glacier, were picked up from the underlying earth, or bulldozed by the glacier as it advanced. As the ice retreated and melted at the end of the Ice Age these sediments were dumped and left behind.

In Sneem, these deposits mostly take the form of moraines. Moraines are poorly sorted and unconsolidated mixtures of mud, sand, clay, pebbles, and boulders, which were carried and deposited by glacial ice. The landscape of Sneem has a distinctly hummocky appearance with vast swathes of undulating hills. These irregular mounds of glacial debris are known as hummocky moraines and are believed to form during periods of glacial stagnation when the ice gradually melted and lowered sediment to the surface or by the thrusting of already deposited sediment by minor ice advances.

The ice sheets also left behind hundreds of boulders of various sizes which lie scattered across the fields. Across the loop, some of these huge boulders are perched in precarious positions while others have been fractured and split into distinct segments. These oddities of erosion are caused by freeze-thaw action. This type of weathering occurs when water infiltrates cracks in the rock. When the temperature drops, this water freezes and expands, forcing these cracks to widen. As this process is repeated the boulder eventually splits and breaks apart to dramatic effect.

Dromtine Lough and Standing Stone

Dromtine Lough, as well as the smaller Lomanagh and Black Loughs are glacial kettle lakes. Kettle lakes form as ice chunks break away from receding glaciers and the rafted blocks of ice become buried in sediment. Gradually, the residual ice block melts, forming a depression in the sediments which is infilled with meltwater. A record from  Dúchas , Ireland’s National Folklore Collection, alludes to a legend of a boat full of gold having been hidden within Dromtine Lough.

Dromtine Standing Stone is found to the north of Dromtine Lough. This single standing stone that crowns a ringfort and towers 4.4m, is believed to date back to the Bronze Age. Similar standing stones are scattered across the country, with roughly 600 recorded in Kerry and Cork. While their exact function is difficult to determine, it is commonly suggested that rituals or other ceremonies may have taken place around them. Other proposed functions include rubbing stones for cattle, structures to help support stone walls, markings of burial places, boundary markers, indicators of routeways, or astronomical observations. In all likelihood these standing stones served a variety of purposes, however time leaves us guessing how these impressive structures may have been used.

Considerable folklore and legend surround these mystic and enigmatic structures. A reoccurring folk explanation of these features is that they are petrified spears, the remnants of battles between the giants of ancient mythology. There is a long-established superstition in Ireland that disturbing these sites can bring bad luck which may be part of the reason that so many have survived.

Rock Features

Along the trail, you will frequently pass outcrops of Old Red Sandstone. When surrounded by such large-scale geological marvels it is easy to skip past these small features but take a moment to delve a bit deeper and appreciate the records of past environments contained within these unassuming rocks. The rocks appear green, purple, and red in colour providing clues to where they were the sediment they contain was originally deposited. Green rocks generally indicate deposition in a wet environment, such as the river channels and lakes that covered the area during the Devonian. Red and purplish rocks most likely suggest deposition in the drier areas that would have existed between channels.

The large-scale bedding layers visible in the mountains record the vast amounts of time required to accumulate such quantities of sand and silt. By comparison, the smaller centimetre to millimetre scale laminations or layers found along the loop record deposits that could have easily accumulated within a human lifetime. These fine layers represent changes in sediment supply and may be related to seasonal or annual events such as floods.

In some areas, distinctive white bands can be seen cutting across the rocks. These are veins of the mineral quartz. Quartz is generally colourless but can appear in many different hues due to the presence of impurities. The white colour of the quartz seen along the loop is caused by the presence of gasses and liquids trapped within the crystals. The development of veins is associated with the circulation of hot fluids containing dissolved minerals through the cracks and fractures in the rocks which formed during mountain building. As the fluid cools the minerals are deposited through crystallisation and solidification. 

Blanket Bog 

Blanket bog is a type of peatland which forms in areas of high rainfall and low evaporation. Blanket bogs are found in the lowlands of western Ireland and upland mountainous regions. Blanket bogs likely began forming around 4,000 years ago with formation strongly linked to human activity. Prior to this, fen peat and raised bogs had been forming for thousands of years.

During the last glacial period plant life could not withstand the harsh conditions and so retreated further south to warmer areas in Europe. As the ice sheets melted plants gradually recolonised Ireland, with tundra giving way to woodland. The earliest species to become established were juniper (aiteal) and birch (beith), followed closely by hazel (coll) which was succeeded by the arrival of the tall canopy trees like pine (péine), elm (leamhán), yew (iúr), and oak (dair).

By the time the early Mesolithic people arrived in Ireland, the country would have been densely populated by deciduous and pine forest. While Mesolithic people may have had some impact on these woodlands, it is during the Neolithic Age with the advent of farming that land clearance really began to take a toll on the landscape.

As forest clearance spread, soil became vulnerable to leaching, which is the loss of water-soluble minerals and nutrients from the top layers of the soil, and as a result, became more acidic. The accumulation of leached materials deep beneath the soil formed an impermeable mineral layer which restricted drainage. This created waterlogged and acidic conditions under which plant material does not fully decay and instead forms peat. Over thousands of years, this peat has built up to form blanket bogs, creating a rare and biodiverse habitat.

Cotton Grass or Bog Cotton (Ceannbhán), is a particularly common sight in these bogs. This sedge is instantly recognisable by its charming fluffy white tuffs which tremble and dance in the wind.

River and Streams

The Fermoyle Loop has a unique setting as it allows the changes in river systems as they mature to be traced as the streams and rivers meander in and out of view. While Sneem is home to impressive geologic antiquity, it is worth noting that geologic processes are constant and ongoing. Rivers are among the most important modern geological agents and have the capacity to mould and shape the landscape by eroding, transporting, and depositing material.

The rivers that flow through Sneem have sources in the Dunkerron Mountains. Here the streams charge rapidly down the steep slopes, incising channels and cascading as waterfalls over mountain sides. Gradually as these streams mature and reach lowlands, they become wider and gentler and flow in looping meanders. At this stage, deposition dominates over erosion with material being deposited to form pebble banks. In Sneem village, the river nears its final stage as it enters the estuary and begins to feel the influence of sea water. Find out about the wildlife that frequents these rivers and streams in the Lomanagh map  here .

As the rivers cut through areas of rocky outcrop, they are passing over the ripples and current marks created by the ebb and flow of the floodplain channels that dominated the area around 380 million years ago. How will this landscape continue to change in the future and what mark will Sneem leave in the geological record in millions of years to come?

Kenmare River

Throughout the Quaternary, the Irish coastline experienced considerable variations in sea level due to the oscillating growth and decay of ice sheets. During the last glacial period, so much water was locked up in ice sheets across the world that global sea level was roughly 120m lower than present. As these ice sheets began to melt, sea-level rose rapidly. While the finishing touches to the topography of the land were added by the action of the glaciers, the shape of Iveragh’s coastline was largely controlled by this huge influx of meltwater.

Kenmare Bay, sometimes referred to as the Kenmare River, an idiosyncrasy originating in a past classification made to safeguard salmon fishing rights, is a product of these rising sea levels. Kenmare Bay is a drowned valley which formed through the flooding of lowland by rising seas. The drowning of valleys often results in the formation of extremely irregular and indented coastlines which are often accompanied by many islands which are the summits of partly submerged hills, as clearly illustrated along the coast of Kenmare Bay. Beyond Kenmare Bay, views of the Beara Peninsula and the Caha Mountains are spectacular on a clear day.

Boat tours of Kenmare Bay exploring the caves, cliffs, and islands, as well as the area’s history as a smuggler’s haven are provided by  Skellig Coast Discovery  and depart from Wavecrest in Caherdaniel.

Rock Art

Just after setting off on the downhill portion of the Fermoyle Loop, a detour leads to a rock surface containing rock art in the townland of Tullakeel. Similar rock art is found at Dromtine where a carved boulder is found on the slope descending into Lough Dromtine.

The rock art found at these sites is known as Atlantic rock art and consists of engraved imagery on natural rock surfaces, typically boulders and outcrops. This type of rock art dates to the Late Neolithic to Early Bronze Age periods (3000-1500 BC). Atlantic rock art is also found in Spain, Portugal, Brittany, and Britain.  

Here, the rock art is predominantly made up of cup and ring motifs, which are circular depressions often surrounded by concentric rings. While the meaning and significance of these rock carvings is not fully understood, their locations are believed to be influenced by several factors including views of water, routeways and landscape features and some perhaps mark places of worship and pilgrimage.  

Read more about Ireland’s fascinating rock art in the  Prehistoric Rock Art in Ireland  pamphlet created by the Heritage Council. Aoibheann Lambe, of Rock Art Kerry, has carried out extensive research on the rock art of Kerry and you can watch her lecture on the topic  here . 

Wildflowers

The Fermoyle Loop is a wonderful trail to do seasonally to observe changes in the landscape. As well as spectacular geology, in the spring and summer months there are a plethora of wonderful wildflowers and plants to admire as the hedgerows burst into bloom.

While the below list barely scratches the surface of the beautiful wildflowers that are found along the Fermoyle Loop, you can read more about what to look out for in our ' Spring on Iveragh ' StoryMap.  Wildflowers of Ireland  is a handy website to help with ID, find the Irish name, and interesting nuggets of information.

The Cuckoo Flower or Lady’s Smock (Biolar gréagháin), with its dainty flowers resting on slender stems is a sure sign that spring has arrived. This common flower is a champion of wet habitats and can be found across marshes, damp meadows, woodlands, and roadside verges. Keep an eye out for these intricately veined and overlapping white to pale pink petals from March to June. The name of this flower is related to the fact that blooming through May, it coincides with the arrival of the first cuckoo.

Come late May to Early June, Iveragh becomes awash in the rich purple of Foxgloves (Lus mór). These tall, slender plants are among the peninsulas most elegant. During the summer months, it is impossible to miss the proliferation of purple flowers that are found dripping from hedgerows, ditches, and woodlands. There are many stories used to explain the name of this flower. The scientific name Digitalis Purpurea means ‘finger-like’. In Ireland, the fox is suggested to come from ‘Folk’s Gloves’- a reference to fairies and supported by the frequent the flowers referral to as fairy bells.

Another species found in a number of areas along the loop is Forget-me-not (Lus míonla). These uncomplicated flowers are pretty, bright, and joyful. Readily identified by its blue five-petalled flower with yellow centres. This species is found in both the hedgerows and in the boggy areas, where amassed in clumps the flowers create a delightful floating mass of sky blue.

Honeysuckle (Féithleann) is a flower whose heavenly scent will likely reach you before you spot it. Found twined through the hedgerows these distinct pale flowers with their long tubular two-lipped arrangement can be found from June to October. There is much Irish folklore attached to Honeysuckle and these flowers have been associated with good luck, protection from evil, and money.