Burren and Cliffs of Moher UNESCO Global Geoark Articles 2023

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The Burren and Cliffs of Moher UNESCO
Global Geopark team would like to wish
you all a wonderful, healthy, and sustainable
Christmas.
As a gift from us, here is a collection of
interesting & insightful articles about our
wonderful Geopark which were written by
our resident Geologist Dr. Eamon Doyle.
We hope that you enjoy them.

Mud Ripples
Sedimentology is the study of how water (and wind or
ice) erodes, transports and deposits sediment such as clay,
silt, sand and even boulders or a chemical precipitate.
Studying sedimentology is vital to understanding the
processes that formed ancient sedimentary rocks. The
laws of gravity and fluid dynamics haven’t changed over
time and the study of sedimentology is heavily influenced
by the study of modern sedimentary processes. In
sedimentology, the present is the key to the past.
While the rules of physics haven’t changed over time,
the surface of the Earth has, and the variety of different
environments has changed too. This adds an element of
uncertainty to interpreting ancient environments, as some
proccesses may have operated in combinations that we
don’t see today. For example, we take the surface covering
of plants on Earth today for granted, but 500 million years
ago there were no land plants holding surface sediment
together so erosion would have been more intense.
The good news is that everybody can be a
sedimentologist! Just go to your nearest beach and watch
how the patterns in the sand change over a day. The most
common sedimentary features on beaches are ripples.
Ripples are the irregular ridges of sand that are shaped by
the changing tidal currents and waves on a beach. They
come in a wide variety of shapes and sizes and over the
last hundred years the different conditions that produce
different ripples in sand have been very well understood.
Much of the work was done in laboratories using artificial
sand, and currents of different strengths flowing in
confined structures known as ‘flumes’ as well as observing
modern processes on beaches and rivers.
Typical ancient ripples that formed in the same way as
the ripples on your beach can be seen on some of the
Moher flagstones that make the barrier wall at the Cliffs of
Moher.
Mud ripples are a bit different and far more rare. Until
very recently they had never been found in Ireland. We
were delighted to find some here a couple of years ago
and have recently published a paper in the Irish Journal of
Earth Sciences on their significance.
Mud ripples were named that because they superficially
resemble normal ripples. However, they are formed under
different and very particular circumstances; when erosive
currents flow over semi-consolidated mud. The currents
erode parallel rows of pits perpendicular to the current
direction, these then get buried as the current wanes and
the sediment being carried is deposited, filling in the
pits. So they are formed by single event flows, essentially
floods, that can happen underwater and far offshore,
sometimes triggered by heavy rainfall on land that caused
sediment-laden rivers to flood into the sea.
These mud ripples are evidence of monsoonal rains that
fell 318 million years ago when we were near the equator.
Figure caption: 318 million year old mud ripples from the Gull Island Formation, found near Slieve Elva.

Geology Evening Course. Stone, Water and
Ice: The Burren – A landscape shaped by Time
Over the last dozen years the Burren and Cliffs of Moher
UNESCO Global Geopark has run an evening course with
the Burren Outdoor Education and Training Centre in
Turlough, Bell Harbour. The aim of this course is to make
the geology of the area accessible to all those who have an
interest in the Burren landscape and a couple of hours free
time in the evening, once a week in Spring. The course has
been hugely successful, with over 200 participants so far,
giving the Burren the best-trained population of amateur
geologists in Ireland.
The desire to understand our surroundings is a very deep
and primal urge in humans, and faced with the unusual
landscape of the Burren and the spectacular Cliffs of
Moher there is little wonder that we want to know how
they formed. To be able to provide this information in a
friendly environment is one of the highlights of the year
for us.
Keep an eye on the Geopark’s Facebook page for details
on how you can sign up to the 2024 Geology evening
course.
This year’s course started with an introduction to some
basic geological concepts, with the aim of getting you to
look at rocks in a totally new way. The next class looked
at the Earth as a whole and how the planet works and
how the Burren fits into a very big picture, including
the recent Earthquakes in Turkey. In class three we
looked at the limestone rocks of the Burren, with plenty
of samples and introduced geological maps. Following
that we outlined the geological history of the Cliffs of
Moher and got a chance to examine local fossils and their
significance. Week five, our guest lecture spot, was an
important part of the course, where we invited experts
who have worked in the Burren to share their expertise.
This year Dr. John Murray (University of Galway) and Dr.
Breandán MacGabhann (University of Limerick) spoke
about a fascinating local fossil which Dr. Eamon Doyle
was fortunate enough to be involved with and which has
been published recently in an international academic
fossil journal. We snuck in a local fieldtrip for half a day
on Sunday before returning to the classroom on April 4th
for the final class on Burren landscape, caves and karst.
The course was presented by Dr. Eamon Doyle, the
Geopark geologist and Colin Bunce the Burren cave
expert. Between them they have asked most of the
questions you are likely to ask and found answers to many
of them, which they enjoy sharing.
The course is supported by the Burren and Cliffs of Moher
UNESCO Global Geopark managed by Clare County
Council, Geological Survey Ireland, Burren Outdoor
Education and Training Centre and the Limerick and
Clare Education and Training Board.
Figure caption: Evening Course fieldtrip looking at local rocks at Fanore Beach

The secrets of Lough Inchiquin
Lough Inchiquin is a wonderful, relatively deep lake
on the edge of the Burren. It has challenged trout and
pike fishermen for generations and provides a relaxing
amenity for both locals and visitors in a beautiful setting.
However, most visitors don’t realise that deep within
Lough Inchiquin are hidden secrets, buried in the mud at
the bottom of the lake.
These secrets are biological and chemical information
continuously stored in the mud over thousands of years.
Lakes act like landscape storage devices; rivers flowing
into a lake slow down and anything carried in by those
rivers can be deposited on the lake floor. The rivers that
flow into a lake contain the chemical and biological
imprint of the land they are draining because much of
what happens on the land surface gets washed into rivers,
particularly during heavy rain events.
Lough Inchiquin has been fed by rivers flowing off the
Burren since the end of the last Ice age, this means we
have a record of what was happening on the surface
of the Burren stored in the mud at the bottom of the
lake. By analysing the layers of mud for biological and
chemical signals it is possible to build up a story of how
these signals change over long periods of time and to
understand what was happening in the Burren landscape
thousands of years ago.
The Palaeoenvironmental Research Unit at University
of Galway did just that. Funded by the Irish Research
Council the team extracted a 10m sediment core from the
deepest part of the lake (30m). Plant material for Carbon
14 dating was extracted to identify the age of the mud
layers. They then examined the preserved chironomid
fly larvae. These insects are important for analysing
past climate as different species prefer different water
conditions. The preserved pollen and the chemistry of the
mud was also analyzed.
The Carbon 14 data revealed that the core spanned
over 4,000 years from the Late Mesolithic to the Late
Bronze Age (4,500 to 660 BC). Analysis of the deepest
(and therefore oldest) part of the core suggested mostly
woodland vegetation, with little grass and very little
nutrient input from 4,500 to 3,100 BC. However, in the
time period from the Late Neolithic to the Early Bronze
Age (2,870-1700 BC) they found pollen from cereal
suggesting widespread farming was taking place, a change
in the type of insects indicating increased amount of
nutrients (from soil) being washed into the lake and a
decrease in tree pollen.
This confirms that the people that built many of the
wonderful tombs in the Burren during the Bronze Age
were actively working the land as farmers and this
resulted in significant loss of soil at that time, a particular
risk for thin limestone soils in a karst environment like
the Burren. Modern farming practices in the Burren
minimize those risks.
This study is an important reminder that the actions of
humans can have a long-term impact on the environment,
the evidence of which will live on long after us.
Figure caption: Lough Inchiquin, Corofin.

Fishing for clues to ancient marine
biodiversity
Finding fossils can be compared to fishing; the chances
of catching anything are small but the results are often
amazing. Most animals that lived millions of years ago are
not preserved as fossils, they were either eaten by other
animals or decomposed by bacteria.
Unravelling the biodiversity of ancient seas that no longer
exist can therefore be difficult. Recent discoveries are
shedding new light on the fish that swam in the ancient
seas that eventually turned to rock to form the Burren and
Cliffs of Moher. Previously, nothing was known about the
fish that lived here 320 million years ago.
We now know we had sharks. Sharks have a body made of
cartilage, which is only rarely preserved and usually only
their teeth are preserved as fossils. The 2cm shark tooth
pictured here has a main central point and lateral pointed
cusps. This is the tooth of a shark that was designed to
grip and it would have been an active hunter of slippery
creatures, probably other fish. The shark would have been
over 1m long.
In addition to this shark we now know we had other,
much smaller sharks. They had teeth only 1mm long but
despite their size they would also have been active hunters
of swimming creatures. Interestingly, we know they had
large eyes, so they would have been able to hunt in darker,
deeper water. They would have been predators of smaller
creatures but the prey of the larger sharks.
Some sharks do not have sharp teeth, they have flat hard
plates that are used to crush shells. These fish would have
lived near the bottom of the sea, taking their prey, such as
snails, from the seafloor. These may have hunted by scent
rather than eyesight.
Apart from sharks, we also have examples of fossil fish
that are the ancestors of all four-legged creatures. These
fish have fins that are lobes and it is from this group of
fish that tetrapods evolved by transforming the bones in
their fins to the bones that became the arms and legs of
dinosaurs, elephants and ourselves.
Finally, we now know we have fish fossils that are the
ancestors of what would become the most common type
of fish swimming today such as cod, salmon, herring etc.
These would have eaten a broad variety of food and would
have been prey themselves, however they had much
tougher scales than most of our modern fish, so would
not have been easy prey.
The rocks of the Burren and Cliffs of Moher are revealing
that there was a complexity to the biodiversity of the fish,
and therefore their prey, that we were previously unaware
of in those ancient seas.
We are currently losing the biodiversity of fish in our
modern seas and oceans due to over-fishing, pollution
and climate change. What legacy will be preserved as
fossils for future generations to find?
Figure caption: Fossil shark tooth from near Doolin.

Geopark Academy conference in Kilfenora
The Burren has a wonderful history of learning that is
kept alive today by groups such as the Burren and Cliffs
of Moher UNESCO Global Geopark, the Burren College
of Art, Caherconnell Archaeology Field School, North
Clare Historical Society, the Burrenbeo Trust all our
National and Secondary schools, the local participants in
the BT Young Scientist competition as well as individual
specialists.
Over the years, lots of people have come and gone from
the Burren, exploring, searching and discovering. Some,
such as Tim Robinson have left a mark (and a map)
that is universally recognized and valued, but for many
other students and researchers the information they
find gets a little lost in libraries and obscure academic
journals, and often that information is only presented
once at a conference in one of our national universities
or sometimes an international conference. For many
of us, attending these events is not possible, even if we
knew when they were happening, so inevitably we miss
out on some very good research that is happening in our
neighbourhood.
The Burren and Cliffs of Moher UNESCO Global
Geopark is one of the many groups that value research
in the region. We work with national and international
universities and researchers and we were pleased to
bring some of this information to the public on May
27th/28th of this year. Called the Geopark Academy, this
free conference was held in Kilfenora Community Hall
on the Saturday and there was a Fieldtrip on the Sunday.
We provided this opportunity for people who might not
usually attend conferences to come along and hear about
the work and research a diverse group of people are doing
in the area.
The Geopark Academy conference covered a broad range
of subjects from geology, to archaeology and biology and
even music. There was plenty of opportunity to engage
with the speakers in an informal setting and to provide
them with some local knowldege they are unaware of!
Dr. Eamon Doyle was talking about some of the newest
fossils he has found. Other speakers spoke about recent
archaeology, using new technology in caves in the Burren,
ancient sediment in Lake Inchiquin, the invertebrates
that are so important that we often overlook, and what
happens to the stuff we flush into the water; the impact of
micro-plastics in the sea of the Clare coast.
The fieldtrip on Sunday 28th was lead by Dr. Gordon
Bromley and Dr. Tiernan Henry (University of Galway)
and included a variety of locations that provided
information about the last Ice Age in the Burren and the
unique way water travels in the Burren. There were plenty
chats and general discussions along the way!
Keep an eye on the Geopark’s Facebook page for
information regarding the Geopark Academy which will
be coming back in 2024.
Dr. Daisy Spencer, palaeoenvironmental research unit, university of Galway is closing the presentations at the Geopark Academy 2023 with an in
depth look at pollen and chironimids of sediment cores from Lough Inchiquin and what they tell us about ancient farming

Ostracods; tiny arthropods in shells
The Clare Shale Formation is a geological unit of rock
that extends from Doolin to Slieve Elva and Corrofin and
down to the Shannon Estuary. It is a dark rock made of
thin layers that crumble easily and weathers quickly. It is
mud that was turned to rock over 300 million years ago.
The Clare Shale Formation is well known in the geological
community for the fossil ammonoids (also known as
goniatites) which are very abundant in some layers. These
fossils have been studied extensively here because they
are useful for providing information about the age of the
rocks where they are found. However, the attention that
these fossils were given was matched by the almost total
lack of attention given to other fossils. One exception
being the work by University of Galway palaeontologist,
Dr John Murray and his students on fossil conodonts.
One of the reasons for this general neglect is that other
fossils are much harder to find, because they are not
very common and often tiny. Over the last few years I
have been able to find an increasing number and variety
of fossils in the Clare Shales which is telling us that the
biodiversity of the sea at that time was much higher than
previously known.
Ostracods are very small (from 0.1 mm to a couple of
millimetres), so unless you are specifically looking for
them you are unlikely to come across one. They are
unusual because they live inside paired shells (technically
called a carapace), so they look like small bivalve molluscs
(such as mussels) until you see what’s inside. Inside there
is a creature that looks like like a shrimp. Their antennae
and legs can protrude from between the shells and they
can move about on the seafloor and some are excellent
swimmers.
While the shells are very common, we very rarely find the
animals inside in the fossils, they usual decompose before
the fossilization process. The shells have a wide variety of
forms and ornament and these are used for identification
of fossil ostracods. One of the interesting things about
the new fossil ostracods from the Clare Shale is that while
they are very rare (only 10 individuals found so far) there
is at least four different species. Further research is needed
to see if we can identify what particular environment
these fossil ostracods were living in, 320 million years ago.
One of my most recent fossil finds belongs to a group of
animals known as ostracods. Ostracods are arthropods,
that is they have jointed limbs and are related to crabs,
spiders, centipedes and insects. The oldest known fossil
ostracods are over 450 million years old, they are the most
common fossil arthropods and their relatives are still alive
and well today in almost every environment where there
is water.
Figure caption: Microscopic fossil ostracod shell (1.5mm wide) from the Clare Shale Formation.

Lingula - a different kind of brachiopod
Around the coastlines of Asia and the Pacific Ocean lives
a brachiopod called Lingula. It inhabits shallow coastal
areas where it burrows into sandy or muddy seafloors.
Unlike most other brachiopods it can live in brackish
water habitats such as tidal mud flats. And, unlike any
other brachiopod, it is eaten by humans.
Typically, brachiopods have two hard shells made from
calcium carbonate. Lingula is different in having shells
made from chitin, protein and calcium phosphate. This
makes the shells more flexible, a bit like your fingernails.
Lingula is also different than most other brachiopods in
being classified as an ‘inarticulate’ brachiopod. This does
not refer to it’s inability to speak, it refers to the way the
two shells are connected together, or articulate with each
other. The majority of brachiopods have complex sockets
and corresponding processes in their shells that interlink
with each other to form a rigid hinge mechanism, Lingula
doesn’t. Many brachiopods have a ‘pedicle’; this is a
flexible, leathery stalk that extends from the shell to attach
the brachiopod to a hard substrate. Lingula has a relatively
large pedicle, however it doesn’t use it to attach to rocks,
it uses it to help it burrow into sand and to to hold the
animal in place in its burrow.
Given these differences it is worth asking why Lingula is
considered to be a brachiopod at all. The reason is that it
has a feeding structure (a ring of tentacles) known as a
‘lophophore’ which is common to all brachiopods. This is
one reason why brachiopods are in a different phylum to
oysters and mussels, which are molluscs.
Brachiopods similar to Lingula are known from over 500
million years ago. They have survived mass extinction
events, environmental changes and predator evolutionary
challenges relatively unchanged. Thier tough flexible shells
held together by strong muscles make them a difficult
subject for predators.
I have found some in the 320 million year old shales from
Doolin to the Spanish Point. Unlike modern Lingula,
many ancient examples are thought to have lived in
relatively deep water and they could survive conditions
that other brachiopods couldn’t. So we find them in
rocks that show evidence of low oxygen levels and high
mud content which other brachiopods could not survive.
Modern Lingula uses a molucule called Hemerythrin
which is similar to our own Haemoglobin in using iron
to bind the oxygen that is vital for living. It is likely the
ancient examples used the same molecule.
Until recently all the fossil brachiopods that looked like
Lingula were called Lingula, however it is now considered
that all the older ones, such as they ones found here in
Clare are a different genus. However, there is currently no
agreement among palaeontologists on how these older
ones should be named. Like the slow-changing evolution
of the brachiopod itself, the changing of fossil names can
take some time.
Figure caption: The ancient relative of the brachiopod Lingula, from the rocks of northwest County Clare.

The ancient craft of iron smelting at
Caherconnell Fort
Iron is the fourth most abundant element in Earth’s crust,
the thin veneer on the surface of the Earth that we live on.
However, it is the most common element on Earth, taken
as a whole, because it is particularly concentrated in the
Earth’s core. All the iron on Earth was formed from fusion
of lighter elements in the cores of distant supergiant stars
at incredible temperatures of billions of degrees. The
fusion process stops at iron because it is the most stable
element, this is why iron is so common; it is difficult to
change into other elements.
As the Earth formed from coalescing particles over
four billion years ago, the iron sank to the core where it
remains today. Fresh iron is transferred to the surface
of the Earth every time a volcano erupts. Iron combines
readily with oxygen to form iron oxide, also known as
rust, which has a typical red/orange colour. In fact, when
the first oxygen was being formed on Earth by simple
organisms three billion years ago it didn’t actually get to
stay in the atmosphere as it combined with all the iron
on the Earth’s surface. This formed large deposits of iron
minerals which are the source of most of the iron that
is mined on Earth today. It wasn’t until all the iron was
oxidised over a billion years later that oxygen was free to
accumulate in the atmosphere. Our blood now uses iron
in haemoglobin to tranport oxygen to all the cells in our
body.
Thousands of years ago, one of our ancestors noticed that
burning wood at high temperatures with certain rocks or
clays produced the hard shiny metal which we now call
iron. Through trial and error this developed into the craft
of ‘smelting’, that is the craft of removing the oxygen and
other elements from the iron minerals to return it to pure
iron metal. Over time, structures known as ‘furnaces’ were
built from clay to improve the efficiency of the process.
New skills had to be developed to work the metal using
intense heat to shape it into useful items, this is known as
‘forging’.
Archaeologists at Caherconnell Fort have discovered
evidence that iron was smelted inside the fort. This
iron was then forged on site to make arrowheads, nails,
knives and other tools. In collaboration with the Irish
Iron Heritage Foundation, the ancient crafts of smelting
and forging this native irish iron are being re-discovered
by a new generation of craftspeople at the Caherconnell
International Furnace Festival this. For those that want
to experience this at first hand they can follow www.
furnacefestival.ie to view details on the festival in 2024.
Figure caption: Caherconnell Furnace Festival 2022

The enigmatic fossil Sphenothallus
The fossil genus Sphenothallus was first described
from rocks in New York state in 1847, by American
palaeontologist James Hall. He described it as a plant.
However, similar fossils had previously been published
under a different name in Ireland by the eminent Irish
palaeontologist Frederick M’Coy in 1844. He thought
they were worm tubes and called them Serpulites. So,
from the very beginning of their recorded published
history, these fossils have been a source of some confusion
for palaeontologists. Since that time these fossils have
been found all over the world and from a wide range of
geological ages, but they are still something of an enigma.
That 1844 record of M’Coy (from Carboniferous rocks
in Leitrim) remained the only known occurence of this
fossil genus in Ireland until very recently when we found
new specimens in rocks near Liscannor and Doolin,
County Clare. The fossils themsleves are quite simple,
being generally described as flattened, gently tapering
phosphatic tubes, usually less than 0.5 cm wide and
around 10 cm long. Some specimens have a small circular
holdfast on the narrowest end which would have been
used to attach to shells or other hard surfaces. None of
the delicate soft-body details of the creature have ever
been found preserved, which makes it difficult to compare
them with other animals.
The most recent interpretation of these fossils by
American palaeontologist Professor Heyo Van Iten is that
they are related to corals, anemones and jellyfish (Phylum
Cnidaria). In particular, he proposes that they are related
to the polyps of certain jellyfish. Jellyfish have complex life
cycles which includes a stage which forms small tubular
polyps that attach to hard surfaces. It is from these polyps
that the jellyfish stage that we are most familiar with is
generated from.
Sphenothallus is usually found in rocks with few other
fossils. This suggests it was able to tolerate conditions
that were difficult for other creatures, in particular it
appears to have been able to survive in low-oxygen
environments. The new fossil discovery from County
Clare tells us that not only did it survive, but it thrived, as
thousands of these fossils are found together. The fossils
are from two different geological horizons and in both
places Sphenothallus appears after a significant change in
rock type, where there is an abrupt change from shallow
water to deep water conditions in the ancient sea. So,
it was a pioneer genus that could colonize new difficult
environments that were inhospitable for most other
organisms.
Interestingly, the new specimens from Liscannor display
some features previously unknown from any other
fossil Sphenothallus, and we are currently working with
colleagues from Sweden and the UK to describe these new
features for publication. This may provide information
that leads to a better understanding of these creatures not
just from County Clare, but internationally.
Figure caption: Newly discovered Specimens of Sphenothallus from County Clare.

Measuring ground vibrations: County
Clare joins an international network
of Earth monitoring
Earthquakes are the result of an abrupt release of energy
underground. The constant movement of the tectonic
plates that make up the surface of the Earth causes
strain to build up in rocks until the rocks rupture, and
the strain is released. This release of energy generates a
series of waves that travel through the Earth which are
felt as shaking on the surface. The amount of energy
released in large earthquakes is incredible, comparable
to the energy released by 100’s of nuclear explosions.
In fact, underground nuclear test explosions are
monitored globally by the same instruments that monitor
earthquakes.
The recent earthquake in Morocco reminds us that largescale
movements of the Earth’s crust, though episodic
and devastating, are a normal occurence. Our thoughts
and prayers go out to the many families devasted by
the Moroccan Earthquake. While Earthquakes are
relatively common in that area, it is over one hundred
years since an earthquake of this scale happened there.
This emphasises the longer timescales that are needed to
understand Earthquake risk in tectonically active areas. It
also highlights that we still cannot predict exactly where
or when an earthquake will occur, even in the most highly
monitored earthquake zones.
By coincidence, the Global Geopark Network annual
conference was taking place in Marakech, Morocco, when
the earthquake struck. While many of the delegates came
from active earthquake zones, for most it was their first
time to experience a significant earthquake event and they
will have gained a new understanding of the immense
power stored in the Earth’s crust from that frightening
experience.
As Ireland is not close to a plate boundary we are
fortunate in being subject to only very occasional, low
energy events such as the earthquake that struck Doolin at
10.24pm on the 6th of May, 2010. The Doolin earthquake
was a Magnitude 2.7 event, whereas the recent Moroccan
earthquake was a Magnitude 6.9 and would have released
over 10,000 times the energy of the Doolin quake, which
explains the amount of devastation caused.
Earthquakes are monitored globally to record their
strength and depth, this gives us vital information
about the distibution of earthquakes which informs risk
management but also provides information about how
the structure of the Earth deep underground that is
otherwise inaccessible. With the assistence of the Dublin
Institute of Advance Studies (DIAS) who are experts in
monitoring earthquakes globally, we have set up a small
seismometer in Ennistymon. This is connected to a global
network which can be accessed online (www.shakenet.
org) where you can watch live seismic monitoring from all
around the globe. Seismometers measure any vibrations
travelling through the Earth, so even if there are no
nearby earthquakes, traffic, trains, waves and even wind
can register their effect via small earth vibrations.
Figure caption: Minor ground vibrations (mostly traffic) captured by the RaspberryShake in Ennistymon.

The exotic soils of the Burren
Soils are so widespead we often forget they are there,
until you go to the Burren and notice that something is
missing!
In general, soils form from the weathering of rock with
the addition of organic matter over time due to the
growth and decay of plants.
Soil formation in the Burren occurs either on limestone
bedrock or on the mass of crushed rocks left behind
after the last Ice age, the glacial boulder clay. The glacial
material is almost totally made of limestone, scraped from
the Burren by the glaciers 20,000 years ago.
When rain falls on limestone it dissolves it slowly, around
1cm per thousand years. The Burren limestone is very
pure calcium carbonate, so when it dissolves it all gets
washed away, leaving nothing behind on the surface.
This means the bedrock doesn’t provide much material
to the soil, which is dominated by organic matter. The
organic matter comes from algae and then plants as they
colonise the limestone surface, their decomposing dead
leaves provide the bulk of the soil. Animal excrement is an
important additional source of organic matter. These soils
form slowly and are usually very thin, but very fertile.
The other potential additional material that can
contribute to soil is wind-blown dust. This may come
from as far away as the Sahara Desert. Colin Bunce and
Gordon Bromley of University of Galway are examining
the possiblity that wind-blown dust (loess) from exposed
glacial material at the end of the last Ice Age contributed
large amounts of this dust to the early Burren soils.
Glacial deposits cover the limestone rock in places and
these deposits are also a substrate for soil formation. Most
of the glacial material in the Burren is made of limestone,
however, if you look closely you will see other types of
rock in there, in particular pieces of granite, quartz and
sandstone. These were initially transported by an ice sheet
flowing from Connemara, which scattered them over
the Burren. A subsequent ice sheet from the northeast
incorporated this Connemara material and it was mixed
into the boulder clay under those later ice sheets.
Because this glacial material is mostly limestone, it will
also dissolve slowly in rain. However, since the glacial
material contains these exotic rocks from Connemara
it is not as pure as the Burren limestone, so when the
limestone in the glacial material dissolves, the quartzrich
rocks from Connemara do not weather as quickly,
and they accumulate on the surface. In some places
thin deposits of glacial material that once covered the
limestone have already dissolved leaving the thin soils on
the limestone bedrock rich in fragments of granite and
sandstone.
Given enough time, most of the local glacial material will
dissolve and only a thin scattering of Connemara rocks
will remain on the limestone surface!
Figure caption: Thin soil forming on limestone bedrock (l) and on glacial boulder clay (r). Both soils contain exotic rock fragments from
Connemara

Dunbarella, a fossil scallop found in the
shale of northwest Clare
Dunbarella sounds like a fossil that might have been
named by the comedian and actor Pat Shortt as
‘D’Unbarella’, however it was named in 1937 by the
american palaeontologist Norman Dennis Newell (1909-
2005) for specimens found in the USA. Across the states
of Kansas, Oklahoma, Missouri and Nebraska we find
rocks of the same age and type as we find in northwest
County Clare, and they contain some of the same fossils,
one of which is Dunbarella.
Dunbarella is a bivalve, which means it is a mollusc
that lives within two shells held together by a hinge and
internal muscles, so it is related to our modern mussels,
oysters, clams, and in particular, scallops. Bivalves make
their shells from calcium carbonate which they extract
directly from seawater, and it is their hard shells that make
them ideal candidates for being preserved as fossils.
Modern scallops are a seafood delicacy and it is the
internal muscle that we sear in a hot frying pan with
garlic. This muscle holds the shells tightly together to keep
out predators but can also be used to forcibly clap the
two shells together and expel water to allow the scallop to
swim for short distances.
Dunbarella was thriving 320 million years ago, it is
usually found as a fossil in shale, often with no other
fossils that lived on the seafloor. Fossil plants that were
washed in by storms or fossil goniatites and fish that
swam in the clear water above but fell to the seafloor after
death are the only other fossils. Muddy seafloors can have
very low oxygen levels and it is thought that this is why
there are few other fossils found with Dunbarella. There
has been some debate about how it was able to survive
in these low oxygen conditions, one possibility is that
they had symbiotic algae that didn’t need oxygen, living
inside the shells and that these would have contributed
energy to Dunbarella, while Dunbarella for their part gave
protection to the algae. As these minute organisms are
unlikely to be found preserved as fossils we will probably
never know.
Modern scallops that live in shallow coastal water are
unique among bivalves in having a large number of
small light sensitive eyes that respond to movement, and
it is possible that their fossil ancestors had them also,
however, as soft tissues decompose rapidly after death we
are unlikely to find them in fossil Dunbarella even if they
were present.
The next time you enjoy delicious scallops from Galway
Bay, consider their smaller, 320 million year old ancestors
that were living in a long-gone sea but which survive as
fossils in the shale rocks of Doolin, Lisdoonvarna and
Slieve Elva.
Figure caption: The 320 million year old fossil bivalve Dunbarella from the shale rocks of Doolin.

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