Field Trip Reports 2011Field_Trip_Reports.html

27th to 30th June - Inishowen

The long field trip this year was to the Inishowen Peninsula, an area the club last visited in 1998. This time we were based in the Ballyliffen Spa and Golf Hotel and although we revisited some sites there were new ones included in our itinerary; not least among these was a trip to Inishtrahull. We commenced our excursion programme on Monday 27th with a historical visit to Carndonagh and ended on Thursday 30th with a botanical visit to Inch Level. Between these visits we had more botany, archaeology/history, geology and zoology.


Thanks go to our sectional secretaries, Margaret Marshall (botany), Jim Rutherford (geology) and Pamela Thomlinson (zoology) who helped organise the programme and shared their expertise with us. We are grateful to Bernard Anderson for his expert input to the geology of the region.



We are indebted to Andrew Sides for facilitating the trip to Inishtrahull and also to NPWS warden Emmet Johnstone who accompanied us and was an excellent guide to all aspects of the social and natural history of the island. As usual the final evening was devoted to a conversazione at which an amazing variety of exhibits were displays by the ever-resourceful Field Club members. 


Archaeological report


The excursion secretary used the following publications to assist her in planning the archaeological/historical visits; The Heritage of Inishowen:  Its Archaeology, History and Folklore by Mabel R. Colhoun, Inishowen: a journey through its past revisited by Neil McGrory and Ancient Monuments of Inishowen, North Donegal by Sean Beattie.

Our first visit was to Carndonagh, which in early Christian times was an important ecclesiastical site. The monastic complex was located where the present day Church of Ireland stands. First we viewed the Donagh Cross and its attendant stone slabs which now stand at the side of the road on a specially built platform within an open shelter. The cross is believed by some authorities to date from the last quarter of the 7th century and is important in the development of the cross form cross slab, from where the carving of the cross is completely contained in the slab, to that where the rudimentary arms of the cross extend beyond the carvings, and beyond the stone itself until it reaches the stage as in Carndonagh where the cross is completely free standing.


The Marigold Stone (opposite) situated in the church graveyard was part of the original monastery and depicts three crosses of different origins and geometric design. The state of the carving was compared with the photos (taken more than 20 years ago) in Mabel Colhoun’s book and this started a discussion which continued for the whole of our visit to Inishowen:“what should be done about these monuments which are obviously deteriorating by weathering?”


On Tuesday those people who were not willing to undertake the boat journey to Inishtrahull were conducted around the local area by our vice president Pat Rutherford. The first visit was to The Isle of Doagh famine village. The Famine Village is an outdoor museum that tells the story of life in the area from the Famine back in the 1840s, through the 1900s to the present day. This was followed by a look at the nearby Carrickabraghey Castle. The first castle built on this site was in the late sixteenth century and it was occupied by Phelemy Brasleigh O'Doherty. The castle is referred to locally as "Doherty's Castle". In 1665, it is recorded that it was unoccupied. At that time it had an oval bawn or stone enclosure and seven towers with a square keep. The oldest part of the building is the square keep, which still stands today.


Later in the day they visited Straid Church near Clonmany. Built in 1772, it was in use until 1925. The graveyard is an unusual place with ancient grave slabs tiered in rows almost making a crude pavement, most of these are unmarked. The graveyard was found to be very overgrown.


The group travelling to Inishowen had time to stop off at Clonca Monastic Site.  

This 17th century planter's church ruin is believed to have been built on the foundation of an earlier church associated with a monastic site founded by St Morialagh in the 6th Century. On an inside wall of the church is a grave-slab erected by Magnus MacOrristin (possibly a Scotsman) with a sword and a hurley stick on it. The monastery was one of the most important foundations in the development of Christianity on Inishowen. It's proximity to Carrowmore and another monastic site founded by St Boudan in Culdaff made this area a great seat of skill and learning. Only two high crosses remain - an upright tall cross with one reconstructed cross arm, and the head of another cross. In the same field west of the High Cross, is the head of a 12th century wheel cross lying prostrate with a large base next to it. While we were examining the upright cross and trying to identify the carvings we were closely observed by a cow in an adjoining field.


Man’s occupation of Inishtrahull dates to the Mesolithic period as confirmed by the flint tools found on at least two sites. There is not a great deal of evidence for occupation in the period between the Mesolithic and the modern era. However, a cross-inscribed stone which could date to any period from the 7-9th Century AD was reportedly excavated in 1900 when the modern lighthouse was being constructed. A fishing community of about 100 people was there in, at least, the 19th Century and was abandoned in 1929. We viewed the school house, field boundaries and houses on the centre of the island before walking out to the new lighthouse. The majority of the party also explored the ruins of the old lighthouse on the NE side of the island.


The group came together on Wednesday for a trip to Malin Head stopping en route to look at Doon bridge (opposite) which is the longest stone bridge in Ireland.  Of historical interest at Malin Head was Banba’s Tower. It was originally built as a Martello Lookout Tower during the Napoleonic Wars. The British Admiralty constructed the present tower in 1805. Weather reports, which were so important to local and international shipping, were first recorded at Malin Head in 1870. It then became a Signal Tower for Lloyds of London using semaphore to connect with ships at sea and the lighthouse on Inishtrahull.


Our first visit on Thursday was to Fort Dunree Military Museum (opposite) which was first opened to the public in 1986. Here we were shown a video film presentation in about Fort Dunree, and its history. Then were given a conducted tour of the fort including the underground bunkers which house a collection of artefacts that give meaning and insight into the day to day operation of the Fort. We had time to examine the museum exhibits.

In an adjoining exhibition centre we were delighted to discover a photographic exhibition about Sentry Hill.


We rounded off our historical visits in Fahan at the site of the ancient Abbey of St. Mura, founded in the early 7th century, it has been used for religious activities for over 1000 years. Sited in the graveyard is the interesting St. Mura’s Cross Slab which unfortunately is badly weathered. Once again we were able to compare it with the photographs in Mabel Colhoun’s book. Located in the walls of the graveyard are two artefacts associated with the old abbey, an inscribed Greek cross and a stone thought to be a holy water font.


Legible marked graves date from 1652 and include the names of the early plantation settlers to the area. A grave which aroused great interest was that of Agnes Jones, a nursing colleague of Florence Nightingale, who died in 1868. Our botanical sectional secretary produced a pair of shears and began to tidy up one plot which turned out to be the grave of her uncle and his family.  

 

While at Dunree fort we had been told about the sinking of H.M.S. Laurentic which was lost on January 26th 1917 at the mouth of Lough Swilly. 68 victims of this tragedy are interred in the grounds of the Church of Ireland Church so we were able to visit this large grave and memorial (opposite). This church has associations with Cecil Frances Alexander, who wrote 'There is a Green Hill Far Away', 'All Things Bright and Beautiful' and 'Once in David's Royal City', while living in the rectory.





Geology - Leader: Dr. Bernard Anderson


The 28th June was a truly memorable day when members of one of the oldest natural history societies in Ireland met the very oldest Irish rocks!  To achieve this members of the party boarded two high-speed M Inishowen Boating Company ferries at Culdaff Quay for a one-hour journey to the uninhabited island of Inishtrahull, an isolated rock, about 1.5km by 1.0 km, which lies about five miles north-east of Malin Head.  The island is almost entirely composed of gneiss, a banded crystalline rock of high metamorphic grade which crystallised some tens of kilometres down in the earth’s crust. 

Until recently the Inishtrahull Gneiss (opposite) was regarded as equivalent to the Lewisian Gneiss which composes most of the Outer Hebrides and a coastal strip on the NW edge of Scotland.  However, in the last two decades, new research, largely by staff at the University of Aberystwyth, has persuaded most geologists that Inishtrahull is not Lewisian but the Irish extension of the Rhinns Group gneisses which compose the fault-bounded ColonsayWest Islay block. 

 

The gneisses on the Rhinns of Islay, Colonsay and Inishtrahull are syenitic with an age of about 1780 million years and not the 2900 Ma of the generally granodioritic Lewisian.    (A U-Pb zircon crystallisation age of 1779 + 3 Ma has been obtained for Inishtrahull Gneiss, corresponding very well with an age of 1782 + 5 Ma for zircon from similar rock on Islay).  So the Inishowen Gneiss is certainly old, at least as old as any other Irish rock, but not quite as old as we once believed, and it is almost certainly not Lewisian.


From our own observations during some four hours of sunshine on the island, Inishtrahull Gneiss, a very distinctive, banded and deformed, coarse-grained, salmon-pink and black, syenitic gneiss, comprises some 90% of the exposed rock.  (Syenite is a coarse-grained intermediate igneous rock composed essentially of alkali feldspar or felspathoid with amphibole and/or pyroxene.) The Inishtrahull syenitic gneiss consists predominantly of pink alkali feldspar and black hornblende (both easily recognised with a hand lens), with minor plagioclase, biotite, chlorite and very little quartz.  The dominant foliation is defined by millimetre-scale mafic/felsic (dark and light coloured) compositional banding. 

The Inishowen Dalradian rocks belong to the two youngest Dalradian Groups. The Argyll Group forms the NW part of the peninsula and consists of the sediments up to and including the Culdaff Limestone.  (The Culdaff limestone is the equivalent of the Scottish Loch Tay Limestone, the Dungiven Limestone and the Torr Head Limestone.)  To the south-east the Southern Highland Group includes all of the Dalradian rocks younger than the Limestone.  The whole Inishowen sequence was laid down between about 650 and about 500 million years ago and so is very much younger than the gneisses seen on Inishtrahull.  All the rocks are metamorphosed to low or medium grade schists, quartzites and marble with numerous intrusions of metamorphosed dolerite.

The second stop at Banba’s Crown, the Martello Lookout Tower on the extreme northern tip of Ireland, allowed us to examine typical Slieve Tooey Quartzite.  The hard creamy quartzite is very resistant to erosion.  It and other similar Dalradian quartzites form Ireland’s outer defences against the Atlantic and also most of Donegal’s highest mountains.  The hill top viewpoint allowed the party to recall the previous day’s boat journey to Inishtrahull (clearly visible some 6km to the NE) and also to trace two/three recent raised beaches, known as the Ballyhillin beaches, across the bay to the east. These are the product of the melting of the massive ice sheet from about 15  000  BP. As a result the land rose by as much as 30 metres.

Dr. Bernard Anderson.


The BNFC wishes to thank Dr. Anderson for making this study so enjoyable and successful.   

James Rutherford (Geological Secretary)



Inishowen botany 


On Tuesday 27th June we braved the Atlantic to visit Inishtrahull, north of Malin Head.  Until 1929 about 100 people lived on the island and the outline of their potato fields are still evident; there are 4 hinds and plenty of rabbits so the grass is kept short. We were led round the island by Emmet Johnston, the National Parks warden for Inishowen, and my nephew, Andrew Sides, who works for the Loughs Agency, which covers Lough Foyle.


Inishtrahull, like Tory island, is a site for Scots Lovage (Ligusticum scoticum) - see opposite, a rare umbellifer, which grows on cliffs and rocks near the sea; Emmet climbed down a steep slope to collect a leaf from rocks . We were mystified by plants with shiny bright green leathery leaves and large pink umbels, the size and shape of heads of broccoli, emerging from sheaths . When I described this plant to Con Breene, BSBI recorder for Westmeath, he shewed me a photograph of a similar plant on Inishmaan . It was Angelica (Angelica sylvestris) and he explained that on exposed islands and headlands Angelica does produce these tough basal leaves. Emmet explained that even nettles had been damaged by salt spray in the May gales. In an area, which is normally damp, Tormentil (Potentilla erecta) and Marsh Pennywort (Hyrdocotyle vulgaris) were growing along with Heath-spotted Orchid (Datylorhiza maculata ssp ericetorum), Heath Bedstraw (Galium saxatile) and


Ling Heather (Calluna vulgaris). The dominant colour on the grassland was the yellow of buttercups but pink Centaury (Centaurium erythraea) and white Sea Campion (Silene uniflora) provided a contrast. The yellow, pink and blue flowers of Changing Forgetmenot (Myosotis discolor) were examined with hand lenses.


The landlubbers had reported that Doagh Isle (fortunately for them not an island) was botanically rewarding, so on Wednesday while the geologists examined the rocks on the sea shore, the botanists walked over the grassy headland opposite the Famine Museum. At least 32 named orchid taxa occur in Donegal but this includes hybrids and subspecies, so we were pleased to be able to identify at least 7 in a short visit. Molecular studies are resulting in many species of orchids being re-named which complicates identification. There were masses of Pyramidal Orchids (Anacamptis pyramidalis), Common Spotted (Dactylorhiza fuchsii), a group of Frog Orchids (Dactylorhiza viridis/Coeloglossum viride), Common Twayblades (Listera/ Neottia ovata) and a Butterfly Orchid, probably the Greater (Platanthera chlorantha) in bud. At least 2 species of deep purple Marsh Orchids (opposite) were seen here and in other sites during our Inishowen visit – Broad-leaved Marsh Orchids (Dactylorhiza majalis/purpurella/occidentalis) had solid angled stems and Early Marsh Orchids (Dactylorhiza incarnata var.pulchella) hollow stems.


Our President found the white-woolly Mountain Everlasting (Antennaria dioica) and colour was added with Yellow Rattle (Rhinantus minor),Lady’s Bedstraw (Galium verum), blue Milkwort (Polygla vulgaris) and Eyebright (Euphrasia agg).


Our geology expert, Bernard Anderson, told us that the underlying rocks were rich in magnesium and calcium and so provided a rich habitat. Pyramidal and Marsh Orchids were also plentiful on the dunes at Culdaff.

Windswept Malin Head has low growing heathers–Ling (Calluna vulgaris), Bell (Erica cineraea) and Cross-leaved Heath (Erica tetralix) and the Crowberry (Empetrum nigrum) in fruit with the black berries that give it its name.


Marion Allen relaxed in a “field “ of orchids while others braved the gales on the summit. We did not stop at Lag and Back Strand, where there are some of the highest dunes in Europe, as the Botanical Secretary had reconnoitred and found the area fenced off and very over-grazed.  Golf courses and overgrazing have caused the deterioration of much of the Inishowen machair.


On our way home, we had a brief visit to the Inch Levels where we walked over marsh land with Ragged Robin (Lychnis flos-cuculi), Brooklime (Veronica beccabunga), Meadowsweet (Filipendula ulmaria) and many other wetland plants – we agreed we should return for a longer visit.


Praeger described Alpine plants on Bulbin Hill and Slieve Snacht but we did not have an opportunity to mountain climb  this time.


Margaret Marshall

 

Clonca Cross

Malin Head

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