Slieve League, Co. Donegal
An exploration of wild & interesting places in Ireland and their western European/American flora and fauna…
This page brings together some days walking and some photographs during Summer visits to a very small, but dramatic, micro-habitat in the Sligo/Leitrim Dartry Mountains. This is one of Ireland’s smallest
mountain ranges but it is spectacular in many places with Benbulben’s famous table top and vertical cliffs and Benwiskin’s startling up-thrust but flat high top. Both of those areas are known for their alpine
plants of either Lusitanian or Atlantic origin. Eagle’s Rock is on the eastern side of the Dartry Mountains, just inside Co. Leitrim and the area studied today faces away from the sea but still retains an
exciting flora and some stunning geomorphology
Click image where you see this symbol to get a larger view
Landscape and Plants:
As you leave the mountain pass at Glenade on the road from Manorhamilton to Kinlough a small junction on the
left brings you into the mountains on the western side of the valley. Eventually the road runs out at an old quarry
and the view of the cliffs on the eastern flank of Truskmore open up.
These are a strange (typical Sligo) mixture of measured slopes suddenly giving way to precipitous and vertical cliffs
of no mean height. It is a very attractive landscape. (See image BELOW.) What attracted us to this scene is the flat
plain in the foreground with an even wet pasture and water loving alders and willows leading the eye towards the
sudden and imposing mountain arising from the flat lands.
Mallow, Saxifrages, Sedums and exotic Ferns.
This varied flora is the stock in trade of the these mountains, viewed here from the east, as they are for the more
familiar west facing aspects of the Dartry Mountains. People often talk about the very rare Alpine Saxifrage which
has its only and very limited
Irish occurrence in this
region. (See our article on
1. White Musk Mallow
Malva moschata alba
Our first plant is an unusual
one. Unlike many of the
other exotics described
here, this is probably an
introduced species. The
Mallows in general have
many medicinal and
horticultural uses but are
often an introduced species
emanating from gardens.
But IT IS a very beautiful
plant and persistent and
healthy in its lofty isolation
on these rocky mountains.
2. Yellow Saxifrage
Now, here we have a true
mountain species — the
glorious Yellow Saxifrage.
This is a late flowering
saxifrage and is a typical
plant of limy north western
mountains in Ireland. But it
is very much a speciality of
this location and the Dartry
Mountains in general.
Observing the Geography:
To hell with geology for a while, the place and the nature of the terrain is worth
considering too. Is it the geography, or landscape, or the aspect, or underlying
geology that affects and creates habitats initially?
The three images on the left have been chosen to reflect the nature of this place.
It is surrounded by farmland and towns and beaches but yet it is an isolated
place — a peaceful haven a mile or two away from the main roads.
Was there an Eagle?
There are so many reputed haunts of historic Golden Eagle in Ireland it
sometimes seems that any high pinnacle or massive cliff face could be the former
nesting sites of the Eagle. We shall never know! Eagles have in recent years been
introduced to Glenveagh in Donegal and have been seen prospecting in low and
high grounds around Leitrim and Sligo but have not bred to date as far as we
know. This looks like an ideal pinnacle for a nest. However, it towers over only a
very small area of land over which a large birds of prey might range.
Is there Magic still?
Undoubtedly. Just walking up from the end of the road past an old quarry, into
the glacial ravine, through old moraine and reaching the towers and the
surprising and shocking long and straight cliff behind, gives this place a mystery
that transcends its lack of altitude. As the plants and the horizontal strata in the
pinnacle attest, this is limestone country pure and simple. (More geology later.) It
is also warm sheltered and wet with its back set against strong westerly winds. All
of this contributes to a unique geographical mix with cliffs, tumbled screes and
green forested or grassy slopes all in close proximity.
Dartry versus Glencar
Two similar but different facies and habitats:
Facies is a geological term ascribing qualitative difference to how the character of a rock is expressed by its formation, composition, and fossil content. Two grey limestones but with different characteristics that attest to different
origins and modern qualities which mean they provide a home for animals and plants in different ways. The rock towers shown (LEFT)are the closest we have seen in Ireland to the places you might expect to see Eagles or Vultures or
Condors gathering… in other countries! The sheer vertical cliff shown (RIGHT) is ideal nesting country for Peregrine Falcons. Peregrine and Kestrels and Sparrow Hawks and Buzzards have been seen. In our recent visit a family of
Buzzards — a species now expanding its range in Ireland — were seen soaring and hunting and calling to their young in some coniferous forestation on the lower slopes of this flank of the Dartry Mountains.
What forms these features?
Having examined the Geological Service
website (www.GSI.ie) it seems there may
be two major classification of rocks
If you look at the image on Left, and the
two below, you will note that the structure
of the rocks is very much the same. These
are samples of the Glencar Limestone
Formation, a division of the Upper
Carboniferous period of Irish Geology.
However if you look at the image on the
right, a more solid stronger limestone can
be seen. This is the Darty Limestone
Formation and is well know for forming
the steep cliffs around Benbulben and
other parts of the Dartry Mountains. Here
it sharply defines the narrow gorge to the
west of Eagle Rock with a linear vertical
Dartry Limestone Formation
Glencar Limestone Formation
This lies on top of the Benbulben Shale Formation and forms a
thin band of limestone around that mountain and Tievebaun
Mtn. to the north. It consists of bands of shales and limestones
which may be muddy or contain much silt-sized broken fossil
or other calcite material as well as some sand-sized grains.
There is a regular pattern of thin and thicker beds.
The range of habitats this presents, or the variety of niches
that flowers will find shelter in, is largely due to weathering of
this crumbly rock. Nowadays, it is gentle rain and thawing and
freezing that cracks the rocks. Some while ago it was the effect
of the Ice Age, ice sheets and associated glaciers, carving out
massive channels between the different limestone formations
and depositing moraine near and far producing features like
the Glenade Valley and Glenade Lake as well as smaller
drainage pipes such as the one shown on the left.
All good niches for some rare and exotic plants which benefit
from protection from wandering and grazing animals. Not even
the goats get up here!
Dartry Limestone Formation (top right)
The Dartry Limestone forms the steep cliffs around the Dartry Mountains and sits on
top of the Glencar Limestone. It also forms the upper parts of the mountains but both
are topped with sandstones. At the study site, in the Leitrim townland of Crumpaun,
the tors and inselbergs to the east of the ravine are all composed of the more friable
The Dartry Limestone does not seem to provide as many opportunities for plants to
establish themselves. The map (RIGHT) kindly provided by the Geological Survey of
Ireland lays out clearly the lie of the terrain. The bedding on both limestone
formations is by and large horizontal with some strange anomalies (40° Dip to the
south) on the northern fringes?
(Some fossils and more rock pictures below.)
Holly Fern Polystichum lonchitis …wet scree in middle of ravine.
An uncommon fern in Ireland typical of west coast habitats like this. An attractive fern with long
shiny green fronds with many spiny teeth on the younger leaves.
New Zealand Willowherb Epilobium brunnescens.
NOT a rare or cherished plant. This is an invasive species all the way
from New Zealand and now widespread in mountains and wild places,
often associated with dumping of garden waste.
Roseroot Sedum rosea… in cliff walls
Another classic of Benbulben and other Sligo and Leitrim mountain ledges. Common enough
in the right habitat and grows and flowers profusely. Looks dramatic clinging to cliff faces but
often seems to occur high up in fractured Glencar Limestone like this.
Wall-Rue Asplenium ruta-muraria… among Boulders on scree slopes
Common and widespread but looking very much at home among huge rounded boulders
strewn along the floor and gentle slopes of the channel running between the Dartry Limestone
cliff and the isolated towers on the east side
among large boulders
Wild Thyme Thymus polytrichus… widespread among fallen rocks
The ubiquitous Thyme common in many habitats but it earns its place here with its lush
growth and startling colours and large sized leaves.
Another common plant, this fern
seems to really belong in among
the fallen rocks disturbed by rain
and frost and falling down a
considerable height from the
towering cliffs to the west of the
ravine. The rock looks like Dartry
Other common plants of
To be honest it is the geology and geomorphology of this
place that attracts us; it is a pleasant change from serious
There is much more to be explored here. The full length of
the ravine has yet to be explored and the cliff tops are
exciting as witnessed on Benbulben. The tops are of different
rocks (sandstone) but largely covered in heather.
In future years we hope to add more images of rarities like
the Fringed Sandwort, Roseroot, the Saxifrages — maybe
even the elusive Alpine Saxifrage — to this page?
The Landscape and Structure in more detail.
The Dartry Mouintains, of which this is the easterly flank, provide the dramatic backdrop to the beautiful Sligo coastline and the literary history of
the area. Willam Butler Yeats loved this area and is buried on the coastal plain west of the uplands. All this area is rather undramatic in
sedimentary terms. There are a series of different limestone strata deposited in varying thicknesses one on top of the other. These bedded rocks
lie roughly as they were laid down millions of years ago — apart from being uplifted from sea bed to mountain top! They have not suffered great
geological metamorphosis. i.e. they have not been folded or massively faulted or exposed to great heat or pressure. So the rocks we see and their
fossils are very much as they would have been laid down in tropical seas c. 300 million years ago.
However they have been greatly modified in Quaternary times through the actions of ice and glaciers over thousands of years. These have gouged
out the the dramatic dry corrie shown on LEFT. This photograph shows the path used to enter this land of tors and cliffs and stone strewn ravine.
In the photograph the cliff-forming dense limestone is on your right and the darker Glencar Limestone in on the left. These are all sharply broken
and greatly fragmented pieces of rock that have probably fallen from a considerable height in comparatively modern times. Occasional larger and
rounded rocks have probably remained in the ravine since the last glacier retreated.
This is one of largest single pieces of limestone found along the path through the gorge. It is about 1m cubed. It seems to be a fall from the high
vertical cliff face. We believe it to be Dartry Limestone Formation.
Dartry Limestone Formation.
This classification is based on the GSI’s (Geological Survey of Ireland) description of the characteristics of this formation. It is described as a…
‘massive to thick bedded, mostly very fine grained and dark wackestone… Bedding is picked out by bands and nodules of irregular chert.’ (Wackestone is a
limestone that contains upwards of 10% mud whereas a mudstone is defined as a mudbearing limestone where the mud is less than 10%… i.e
both are an indication of proximity to a coast at time of deposition — our interpretation, please correct us if wrong… (www.wildwest.ie/contactus)
In our sample a very regular band of chert can be found at the
top (?) of the sample but the very fine grained nature of the
rock and and lack of clear bedding is also evident. In their
book, The Geology of Sligo-Leitrim, The Geological Survey also
report that dolomitization (the addition of magnesium) and
silification is pervasive. This may be evident in the very brittle
nature of this sample and the sharp edges formed when the
rock is broken. Chert is a solution rock of limestones akin to
the flint found in chalk cliffs. The denseness and the strength
of this rock formation leads to it formimg the spectacular
vertical cliffs that ring Benbulben and other mountains in the
This pair, and other similar specimens we have seen
at Eagles Rock, are ‘spirifer’ type Brachiopods. These are not
Molluscs but are unique in living through most of the Earth’s
history — from Ordovician times to the present. The
Spiriferids dominated the seas from Devonian to
Carboniferous times and their numerous varieties make them
crucial for dating rock strata but also tricky to identify… any
help would be much appreciated…
Geology and Wildlife!
The endless allure of geology is the knowledge that the ground we are walking on is so much more ancient than
any human involvement. These limestone rocks described here are dated from 300 - 350 million years ago. Also,
they weren’t uplands then but formed deep under sea water as witnessed by the fossils. The turbidity of the rocks
from shales to silt and mudstone to pure blue limestone indicates the clarity and depth of the water at the time of
deposition. Water levels increased and decreased over the millions of years and this fact is reflected by different
rocks encroaching on one another, older rock being eroded and new sand or mud or lime deposits being placed
across older bedding strata.
The spiriferid Brachiopods shown above did not survive into modern times but there is a famous Brachiopod,
called Lingula, that has survived from the Cambrian and is still alive today!
Common Buzzard Buteo buteo… a welcome addition to Ireland’s fauna
Our final image has to be of the Common Buzzard. A group of 3 Buzzards were soaring in the skies most of the
time we were exploring the habitat. It is a welcome sight, accompanied by the loud high-pitched mewing sound
that they emit when soaring. These three birds were evidently from the area and, presumably, bred in the area.
Apart from the contented cruising around in circles carried by the wind high above the mountains, one of the
group was seen anxiously flying fast and low over a conifer plantation making a stronger sharper contact call.
Perhaps there was a young bird at a nest nearby?
Buzzards were largely missing from Ireland until the 80’s but were present in Northern Ireland since 1930. They
have now made a welcome return and can be seen (heard) in most suitable places in Ireland. The habitat for a
Buzzard is trees, both native and conifers, can be on marginal hill land, but just as likely on good farm land. They
are no risk to farming as the biggest prey they would take would probably be young Rabbits and a lot of their
feeding is more like to be on small rodents and other mammals and invertebrates. So enjoy them… listen out for
their mewing and watch them circle endlessly in the sky high above you.
Apologies for neglecting the zoology while being enthralled by the stunning botany and geology.
Hopefully, it will be possible to re-visit this site and photograph more of the bird-life. Any images from this
site would be very welcome. (www.wildwest.ie/contactus)
Eagle’s Rock is ideal Bird of Prey territory. Peregrines can be seen
hunting around these cliffs and they bred this year on the western
slopes of the Dartry Mountains. They appreciate vertical cliffs with
shelter overhead and safe access directly by flying to and from the
This bird (and the images are of the same bird) is from another cliff
nesting site shown (CENTRE). The location is Leitrim and Peregrines
successfully nested in a recess shown on the cliff face
A different type of limestone but with
a similar niche for these wild falcons to
Peregrine Falcon Falco peregrinus… cliffs and mountains.
In the past poisoned by pesticides now recovering and can be seen
all around the country and may be conspicuous with a high pitched
contact call near nesting sites
tolerant of acidic conditions such as found in sandstones and gneisses.
the geology that creates the amazing landscape of Ireland.
intriguing but sadly, probably, the least enjoyed by amateur naturalists.
Service! It is a brilliant resource!
Stratigraphy of Eagle’s Rock and surrounding areas of the Dartry Mountains.
The above map was obtained from the The GSI website using their Public Viewer. The Red and Black texts are added by us based on
stratigraphical information shown elsewhere on that site but not apparent on this part of the image. i.e the various strata are coded with
different colours. There are so many layers within the Upper Carboniferous that these maps carry many colours so we have taken the liberty
to point to the Glencar and the Dartry Limestone formations which are the main players in our exploration of rare plants and animals.
More information can be found for this area (or your own area) by exploring the GSI maps and then walking the hills and searching.
(We acknowledge the volume of fascinating material that the Geological Survey of Ireland has made publicly available…)
Eagle’s Rock is a place redolent with wildlife; we don’t doubt that the Fox
and the Pine Marten roam here. Even in high Summer the visiting warblers
could be recognised by their songs, Grasshopper, Sedge and Willow
Warbler along with the Blackcap. Doubtless there are many more
intriguing stories to be gleaned and we hope to return to this special place
for many more years. The trouble is that there are so many magical places
for animals, rocks and wild plants all along the West of Ireland. (See the
Wild Atlantic Way, for example.)