This is the story of the island of Ireland.
Originating south of the equator,
it's been on a long and dramatic journey.
Travelling northwards through colliding continents
and disappearing oceans,
it has been formed and reformed over 1.8 billion years.
The evidence for this remarkable journey is woven into the fabric
of our mountains, lakes and deepest ocean beds.
Its imprint visible in the stunning ravages of the Ice Age,
in its plants, its animals and its people.
This is a story, 1.8 billion years in the making,
the story of The Island.
Over 1.8 billion years,
the rocks that make up the island were forged together,
making their way north to where Ireland is now located,
on the edge of the North Atlantic.
With all the rocks now in place, Ireland's story moved into
what geologists call the quaternary.
This is the period when our unique landscape, with its valleys,
caves and coastlines, were sculpted by the dominant forces
of water and ice.
At this time, temperatures dropped, causing massive ice sheets to spread
from the poles and cover much of North America and Europe.
At times, Ireland was completely shrouded in thick ice
that extended far out to the sea.
These ice sheets have long since retreated.
But you don't have to travel too far to witness their power.
1,000 kilometres or so to the north-east,
the tremendous force of a glacier still carves the spectacular valley
of Briksdalsbreen in Norway.
The whole area here is like a classroom without a roof
for a geologist. You can see so many glacier features here.
The whole landscape here was formed during the Ice Ages,
when a 2km thick ice cap was covering this area
and the ice was slowly sliding down the valleys here.
The landscapes of Norway and Ireland are very much the same.
They are formed by the same processes.
The only difference is that here, we still have glaciers
that are active and still form the landscape.
But we have to go back in geological time, back to 2.7 million years ago.
After that, we had more than 40 ice ages,
lasting for 100,000 years with ice,
20,000 years without ice and repeating it over and over again.
And that was time periods where we built up huge ice sheets,
one over Scandinavia and one over Ireland and British islands.
And at some points, they also connected with each other.
So also in Ireland, you had this massive glacier erosion.
You had valleys that was carved out by the glacier that was entering
into the fjords and into the deep ocean around.
Once ice accumulates to a depth of about 50 metres,
it begins to move, spreading outwards and downwards
under the pressure of its own weight.
The base of the glacier is in contact with the earth
and is therefore slightly warmer than the rest of the ice,
so a thin layer of water forms,
allowing the glacier to slide over it.
Ice is amazing material.
It behaves like a plastic mass.
At the same time, it can be fragile and crack up.
Like the ice behind me here,
it was formed at the summit of the glacier,
about 2,000 metres above sea level.
Snow is accumulating and then there is a movement down and the ice,
when it get pressurised,
it moves like a plastic material.
You can imagine like a toothpaste
where you squeeze out the toothpaste.
It's the same with the ice and it moves by the force
of the gravity and comes down into the frontal part
of the outer glacier, where it melts.
During the last 2.6 million years, ice has repeatedly advanced
from the poles and then retreated,
carving and moulding the land with every ebb and flow.
It's thought that these vast sheets of ice reached Ireland on at least
four occasions during this time.
But the sheer power of glaciers can erode away all traces
of previous glaciations.
So places like this provide fascinating insights
into what Ireland would have looked like for much
of the past 2.6 million years.
Even though the ice sheets have long since retreated, our most recent
Ice Age has certainly left its mark on Ireland.
In fact, in the last half a million years or so,
ice has been the dominant shaping force on our landscape.
And nowhere is all that carving and sculpting more apparent
than here in Connemara.
These drowned U-shaped valleys are known as fjords.
And in Killary Harbour, in the heart of Connemara, a natural border
between the counties of Galway and Mayo was carved by ice.
The whole mountain landscape here has been directly and greatly
impacted by those glaciations.
Those depressions that we see as we drive through Connemara
on most hillsides and in some areas,
they're backing onto each other almost.
So, they're facing north and south. They're facing all directions.
It gives us an idea of the birth of that ice sheet.
It helps you visualise this sense of massive creaking,
groaning rivers, almost, of ice there,
often compared to rivers much slower in their action.
But accumulation of ice making its way down on its own journey
down into the lower reaches, down into places like the fjord here,
heading out to sea and ending up possibly as icebergs
and floating off into the Atlantic.
So, really, a beautiful journey for something which,
once it solidifies into ice, becomes almost a different entity.
You know, it becomes a living thing, a glacier.
So let's talk about this iconic fjord, Killary Fjord.
How was it created during the last Ice Age?
The fjord here is that accumulation of just the sheer weight of ice,
probably helped by, we think, a fault,
so a deeper geological structure which created a line of weakness
maybe along a pre-existing river valley, but that allowed just a bit
more erosion to occur along a certain line.
And then over time, as the ice came and went repeatedly,
that same slight lowering due to the previous glaciation
would have eroded it deeper and deeper and deeper
until it became then what's known as linear erosion,
where the ice gets focused again and again
along the same avenue, creating these much over deepened valleys.
What are the defining features of a fjord?
They're characterised by this over deepening that I talked about
where you have this concentration of erosion.
They tend to be quite straight because that river of ice
is quite strong in its effect.
So it can bulldoze away the hillside.
So, over time, it straightens and it deepens.
But then when it gets to its outer reaches, and this is characteristic
of fjords in Norway or Iceland, it shallows.
So we think this is an effect of the buoyancy of water
at the outer edge, so it loses that downward erosive power.
And so you tend to get this, what's called a sill
on the outer margins.
And so we have three locations in Ireland where we have deep linear
erosion in a straight line, just like Killary here.
There's also deep erosion at the Swilly and there's also Carlingford.
What kind of rocks are we talking about here and what power
would that glacial ice sheet have to have to literally
slice through it?
Connemara is characterised by very old, very strong rocks.
These are metamorphosed, so they've been baked and pressurised
over multiple mountain building periods.
So this is a very erosive force.
It's the same in Norway.
Some of the hardest rocks in the world are there
and they've been eroded into these very over deepened valleys,
much deeper even than Killary Harbour.
It's not just the ice, it's the rocks themselves
that get taken away from the higher areas of glaciation,
brought down at the base of the ice.
They will scour like sandpaper.
So is this why you chose this particular day
to bring me out here?
This sheet of white in the back that almost obliterates the fjord,
to allow me to experience what an ice sheet
might have looked like. Is that why?
Ice has always been evocative to me,
ever since I started studying it, doing my A-levels,
seeing pictures of Arctic Canada on the wall in my geography class.
And just that visualisation of something that has been before,
has left its signature, its imprint, and is gone now.
So it's been compared in the past to living with the ghosts
of past ice sheets.
It's that idea of a magnificent landscape-changing entity
that is no longer.
But it leaves these tantalising clues all over the landscape
if you know how to look for them, to tell them,
"I was here and this is what I did, and it's up to you now to try
"and piece together that story, if you wish."
That's what keeps me coming back,
so every place I go now in Ireland is almost a curse.
I'm constantly looking for evidence of those past ice sheets.
With each successive Ice Age,
the island was sculpted by the force of advancing glaciers
and the awe-inspiring results are evident
all across the Irish landscape.
But there are other remnants of their erosive power.
As well as what the glaciers carved out
are the deposits they left behind.
Croagh Patrick stands at a mighty 764 metres
and is one of the few peaks that was left sticking above the glaciers
during Ireland's last Ice Age.
I'm not here to climb it, though, but to find out about some of
the most iconic glacial deposits around Ireland's coastlines,
the drumlins of Clew Bay.
So, Robbie, is this one of the few peaks that was left above
the ice sheet during our ice ages?
Yeah, it was, Liz. Croagh Patrick was what's called a nunatak.
A nunatak?
Nunatak is an Inuit word.
When you think about it, like, now up in Canada,
in Arctic Canada, we've got lots of ice.
We've got the odd peak that pokes up above the ice.
So nunatak is the name that they bestow upon those features.
And in Ireland, we know that we had 76 nunataks.
We had 76 little islands like Croagh Patrick
that poked up above the ice.
So how much of it was sticking above the ice sheet?
Yeah, about the top 200, maybe 250 metres.
So effectively the cone.
And the rest would have been ice?
So we would have been deep, deep in the ice here?
When you think about that, you look over there,
you see Nephin Mountain in the distance,
you see Knockanaffrin Mountain over here.
They were the next nearest nunataks.
If you were wrapped up warm enough and if you had the energy,
you could have come down off Croagh Patrick 20,000 years ago,
walked across the ice to Nephin.
You could have kept going.
You could have walked to Ben Nevis and Scotland.
You could have walked across that same ice sheet to Siberia.
And if you really wanted, and you had your Weetabix,
you could have walked to the North Pole.
It's kind of mind boggling.
It is mind boggling.
And let's talk about another feature of our Ice Ages,
the famous drumlins of Clew Bay.
Tell me how these beautiful formations came about.
The drumlins themselves, they are about 20 or 30 metres high.
They're ridges.
And when we're down among them, they look huge.
But when you're at the ice sheet scale, like we are now, looking out
over Clew Bay itself, we can imagine how the bay was swamped with ice.
What that ice did was, it smeared these ridges at its base
and those are the actual drumlins that we see,
those ridges that we see.
There tended to be a rippling effect
and we can see that in their form in the bay itself.
They take the form of really large scale ripples.
And because ice is a fluid medium, just as the sea is, when it causes
ripples to form along a beach, the ice itself started to ripple
at the base and allowed these ribbed forms to actually generate.
Now, legend has it that there are 365 drumlins in the bay,
but I'm not seeing 365. That's not true, is it?
No, and the 365 number, that's very common in Irish folklore.
Is it? There's supposed to be 365 lakes in Cavan
as well as 365 drumlins in Clew Bay.
And there's an ancient Irish warrior, Miach,
who was part of the Tuatha De Danann,
and he had 365 herbs growing on his grave.
But when we actually count the drumlins,
count the ridges within Clew Bay itself,
there's only about 70 or 80 of them,
depending on how high and how low the tide is within the bay itself.
Drumlins are common in Russia.
They're common moving across Scandinavia.
Parts of northern Britain have them.
We have lots of them in Ireland.
And the biggest drumlin fields in the world are in places
like Nunavut and Labrador in Canada,
where we've got hundreds and hundreds of kilometres.
The drumlins of Clew Bay are amongst the greatest and best loved sites
in the west of Ireland.
But the truth is, they are not drumlins at all.
We have 20,000 drumlins in this country,
huge amounts of them.
About a fifth of the country is covered in drumlins. Really?
But the drumlins themselves are parts of much,
much bigger features.
So in essence, they're chains of drumlins
that form even bigger ridge features.
And those features are called ribbed moraines. Ribbed moraines?
Ribbed moraines. And they look like a stack of ribs, effectively.
They're an echelon.
And if we look at the drumlins in the bay, we can see that.
They're long linear ridges, one after the other
in a sort of a ripple or ribbed pattern.
The biggest ribbed moraine field in the world is actually in Ireland.
Is it? Where? It's up in the north central parts of the country,
stretching across from County Leitrim into County Monaghan,
County Armagh, Counties Fermanagh.
And it covers about 100 by 120km,
so that's 12,000 square kilometres of ribbed moraine.
It's the biggest field anywhere in the world
and the biggest ribbed moraine, the biggest feature itself,
is just outside Monaghan town.
We continue to learn more about our geological features, don't we?
But who initially named our drumlins?
The first naming of a drumlin was back in the 1840s
by quite a famous Irish geologist, the Reverend Maxwell Close,
who began studying these ridges and realised that they were actually
illustrating the direction of ice floe.
And he came up with that term, drumlin, from the Irish, droimnin,
which means little hill.
Ice is the dominant, eroding force on Earth,
capable of destroying landscapes and of creating new ones.
The masses of ice that covered the island during the last Ice Age
were up to a kilometre deep, exerting an enormous weight
and pressure on the land.
But then the ice retreated and the island rebounded.
That weight removal from the land
meant that the land was no longer compressed, no longer depressed.
So with the release of that weight then, the land begins to uplift,
like a trampoline.
When you take the weight off a trampoline,
it comes back up again.
All along our coastline is the spectacular evidence
for the island's slow emergence from under the ice.
These are the raised beaches of Malin Head
on the Inishowen Peninsula in County Donegal,
clearly displaying where the sea level was when the land
was under pressure from the glaciers
and where it is now, since the land recovered.
We have an ancient raised beach, or shingle bar,
where Ballyhillan village is,
but below it is the most spectacular evidence
of a raised beach, clearly seen incised or cut into the landscape.
A landscape that has now blanketed the former raised beach,
has become stabilised.
It's become covered in soil.
That is our paleoshoreline, our old shoreline.
But as you make your way around the island,
this ancient shoreline gets lower
the further south you go.
It appears that the ice was not uniform across the landscape.
When colleagues looked at shoreline levels, they found that shoreline
heights was six metres in Antrim and only two metres in Dublin.
So there was a tilt.
There's a tilt evident in the landscape and that appears
to have come from the fact that there was a much greater volume
and weight of ice over north-east Ireland.
Some 300km south of Malin Head is Bottle Quay
on the northern edge of Dublin Bay.
The raised beach here stands just a few metres above
what the sea level is today.
So while the ice was retreating, sea levels were still low enough
to make it possible to walk across the Irish Sea to Britain.
In essence, the land itself underneath the ice was conjoined.
It was part of the same mass.
There was no sea between us at that time.
Once the ice starts melting, huge amounts of meltwater are released
and they end up in the sea.
The sea levels rise gradually and you've got this kind of...
..this catch up happening where the ice margin is retreating
back up the Irish Sea, back up through Ireland,
back up through Britain.
And it's probably around this point here,
somewhere in the vicinity of Dublin.
If you draw a line here between Dublin and Wales,
it's probably around that point that the sea actually catches up
with the ice and you actually get ice being, not being pushed up
by the sea, but being followed by the sea as it moved
back up the channel.
The rocks that make up the island of Ireland have been buried
beneath each other, lifted, folded,
and then carved into the landscape we see today.
And it's these relatively more recent events that have shaped
the island we now know.
The Irish landscape has been etched by ice, the mountains
of Kerry, Cork, Donegal, Mayo, all this spectacular scenery
with cliffs and quarries and U-shaped valleys,
that's all a direct result of the ice.
Our peat bogs, they again are as a result of the ice itself.
The beach is made up of gravels.
It's made up of sand.
There is no fine material in there because, again,
the water washes that out and there are lots of shells.
We've got limpets, we've got periwinkles, we've got cockles,
we've got oysters, we've got sea snails,
all of the various kind of species
that you would see on a modern beach.
The only difference is, first off, this is five metres
above that level.
And secondly, this is about 14,000 years old.
These materials that lie above the bedrock, also,
they protect our ground water, like, because we're a wet country,
we have vast reserves of ground water hidden beneath the surface
that can be exploited for drinking water.
And again, that water is filtered through all of these materials
as the rain comes down through it
and attenuates through this material.
It recharges the ground water and it means
that it's quite clear, it's quite purified.
We've got a huge resource there.
Farming-wise, we've a huge resource because we're at
the Western seaboard of Europe.
We've got lots of rain. That interacts with these materials
and it gives you very rich and fertile soils.
So we have a very rich agricultural legacy because, almost effectively,
directly related to the Ice Age.
Ireland emerged from the destruction wreaked by ice, but the power
of water continued to shape it.
When the ice retreated, rivers and lakes formed in a new
post-glacial landscape, leaving an indelible mark,
from fast-flowing mountain streams
to lowland waterways meandering into the sea.
And this is just on the surface.
Beneath it lies an entirely different world.
At any one time, far more water is stored underground
than in the rivers and lakes above.
This is because Ireland's rocks and sediments are particularly good
at holding water - what geologists call "aquifers".
In Ireland, all rocks are defined as an aquifer,
but some are better than others.
The best types are the ones that have, erm,
layers in, like we can see behind us here,
and also that are quite brittle,
so that when they are subjected to, kind of, earth movements
or tectonic forces, then they fracture.
Even what might appear as solid rock will still contain many
small gaps and fractures.
As such, all rocks are porous.
The more porous the rock,
the more effective aquifers they make.
Because these grains are irregularly shaped,
we've got a lot of space in between of those grains.
So I've got here, I've got five litres of water and I've got five
litres of gravel, and we'll do an experiment to see how much water
we can actually get in.
You can see it seeping down there.
And that's showing we've got an awful lot of space. I'm still going!
So here we are. The water level is just coming up to the surface.
There we go. We've got a ground water flood
and I've got almost half
of that five litre tub of water into my jar here.
Between a quarter and three quarters of a river's flow
comes from ground water that's seeping up into the waterway
all along its base, as is evident with Ireland's longest river.
The Shannon runs for about 360 kilometres
from a pure ground water spring.
The Shannon Pot and the slopes of the Cuilcagh Mountains
in County Cavan was long thought to be the river's source.
But in the last few years, cavers have explored an underground network
that feeds into the Shannon Pot,
and water has been traced all the way
from caves in County Fermanagh, over ten kilometres away.
A good aquifer is one in which we've got plenty of space
and all the space is connected.
So really, that is the key, is number of fractures
and then also their interconnectivity,
and also, to a certain extent, the size of the fracture.
So we can have really big fault zones which can have
quite large gaps between each face of the fault.
So if you think of it like a motorway,
that's the big fracture zone, the big fault zone.
But then you also need the kind of the national roads and the local
roads and even the boreens feeding the water in to that motorway.
The Marble Arch Caves in County Fermanagh are a spectacular example
of this complex underground network.
It's absolutely breathtaking
and such a massive cave.
I mean, do we even know when this was formed, Caoimhe?
It's very hard to date a cave, but what we can do
is we can look at stuff like the stalactites, the sediment
in the cave, and we can carbon date them and see how old they are.
And then we know the cave must be at least older than them.
So for example, there's bits of speleothem, so the calcite
in some of the cave sediments, and we can date that and it indicates
that the cave is at least half a million years old.
It probably would have been formed by glacial meltwater.
So as the glaciers were melting, huge volumes of water
would have been rushing through here, which would
have created, carved out, these big spaces.
We know this is limestone and there's a lot of it in Ireland.
Does all the limestone in Ireland have the capacity to be dissolved
and to form caves like this?
Not really. Some more than others.
It depends on different things, like the purity of the limestone,
so the amount of calcium carbonate in the limestone, how pure it is,
what other things are there.
If there's a lot of mud sediments or shaly limestone,
it can't dissolve the rain, the water can't dissolve it as much.
Also, you need to have some sort of bedding planes
or lines of weaknesses.
So the water doesn't get in through the rock mass.
It flows in through the cracks in the rocks.
Beneath the surface of the island is an enormous, interconnected system
with water seeping into the ground and making its way through cracks,
gaps, sinkholes and disappearing streams.
Usually, in karst environments is the only time you can really get
into...inside the aquifer.
And that's because karst means the rock is soluble,
so it can be dissolved, and we can actually...
It's big enough for humans to go in and see it.
So not all aquifers are karst? No.
Not all aquifers are dissolvable. So this is very special. Yes.
What are the most iconic features that are formed in a cave like this?
The stream is constantly evolving and eroding and dissolving out
new pathways for itself.
There's also deposition in the cave so we can see some of the features
in the ceiling here.
Basically, as the water moves through the rock, you know,
it's acidic, it picks up the lime,
and then when it hits the cave roof,
the carbon dioxide kind of evaporates out.
And then it can't hold that lime as much because it doesn't
have the CO2 to hold the lime.
So a little ring of limestone is left behind.
And as that happens, over time, little stalactites grow.
And as more water comes in again,
they just get bigger and bigger. And then the opposite.
So where that splashes,
again, it degasses, it loses a bit of carbon dioxide.
So you'd always see a stalagmite which grows up
sort of underneath the stalactite.
And if they grow together, over time, they can grow together
and form a pillar.
And there's also other features like curtain, the kind
of curtain drapery almost. Yeah. Beautiful!
And that's where you've got, like, flowing water and it's degassing
and depositing calcite all the way along.
So it's the same principle. Yes, yeah. Stunning features.
I'm curious about the dimpling on these walls, though.
On the rock themselves.
What causes that?
That's called scalloping, and that's formed by,
basically by the water moving through it.
As it's moving so fast, it's turbulent flow.
So in a non-karst aquifer, the flow is considered laminar.
It doesn't kind of have that turbulent.
So as it's twirling around so fast,
it kind of dissolves out these little pockmarks.
Do you know everything there is to know about caves now?
Like, this particular cave? Are you constantly discovering new things?
Yeah. And it is constantly evolving.
Like, the cave itself is evolving, but there's new discoveries
all the time. Even the Marble Arch Caves, the length of it changes
because we've got another passageway that somebody joins
to this passageway, and then suddenly your cave is bigger again.
You're looking at the world's deepest caves, longest caves.
The list just changes all the time.
The karst aquifers have also given rise to one of the most intriguing
water features on the Irish landscape - turloughs.
Pretty much unique to Ireland,
these bodies of water seem to appear on the surface
and then disappear just as quickly.
One of these mysterious vanishing lakes
is the Caherglassaun Turlough outside Kinvara in County Galway.
This is a beautiful turlough.
It's not a particularly dramatic-looking turlough.
But there's so much going on here that's of real interest to us
as geologists, as hydrogeologists, but also in terms of understanding
how water moves in and on the landscape.
And one of the things about this is when we walk around it,
what you won't see is you won't see any rivers coming in
or rivers coming out.
So when you look at it,
it just looks like an isolated body of water.
But we know that it's connected to the sea in one direction.
And we know heading back in this direction,
it's connected to another turlough system,
which is just over the hill behind us, about a kilometre away.
And that system is connected to another turlough system
and another one and another one,
which gets us back up to the Slieve Aughty hills
about 30 kilometres from here.
Turloughs appear on the Irish landscape
because of our island's position in the North Atlantic,
our high levels of rainfall
and the abundance of low lying, relatively undisturbed limestone.
One of the things about limestone is that
if you have the right conditions -
and the right conditions essentially mean getting water onto
the limestone that's chemically aggressive to the limestone -
what it will do is it'll dissolve the limestone and remove it,
and it'll carve a landscape.
And the landscape will have features like turloughs
and like these extended bits of the bedding that we see here
and swallow holes and sinkholes.
Exactly the kind of things we expect to see in karst areas.
And the burren, essentially, that's probably the best known example.
All of that is carved by water interacting with the rock.
And as you can see here, you can track the bed with your eye.
So that's also suggesting that if we were to continue tracking it
in the landscape, we'd see that bed running.
And if we were to continue tracking in that direction, we'd see it.
So once the water gets in there,
there's potential for it to cover huge areas.
Although Caherglassaun is a freshwater turlough
located five kilometres from the sea, it's still influenced
by the ocean and rises and falls with the tide.
This can fill up in a number of days,
but it can take weeks for it to drain.
So what we see is, generally speaking, because we're towards
the end of this system, we're relatively close to the sea,
it's accumulating all the water from roughly 500 square kilometres,
that all of that water essentially has to come through here.
If you put water into a system and it can leave at the same rate,
there's no flood.
But if you put so much water in that it can't leave at the same rate
during the same period of time,
the water in the middle has to go somewhere,
and if it's on the surface, it's in the flood plain.
And if it's on the ground, what happens is those pipes
start filling up and then we get the turloughs rising.
And if there's still so much water, the turloughs will start backing up.
So this turlough will back up the one behind it because it can't drain
and it drains it backs up the turlough behind it and so on.
So the whole way up the system can backfill as well as front fill.
Virtually none of these vanishing lakes can be found anywhere else
in the world, but there are over 400 turloughs in Ireland...
..the result of the role water has played in the island's unique
and remarkable geological journey.
And we look at the place names on old maps that will give us clues.
So anything with turlough in the name,
it probably means we're going to see water on the ground.
Anything with "Powell" in the name is useful as well, because
it probably means there's a hole in the ground where water comes down
or water comes up, and there's lots of other things.
One of my favourite is Owenbristy, which is a "broken river",
which means you have a river on the surface,
then going underground, and then rising, as well.
So, yeah, I think one of the things that's really interesting
about Ireland is that our cultural history
is tied in to our geological history as well,
and that the place names reflect, largely speaking,
the geology and the landscape around us.
I've travelled around Ireland in search of clues
about how and where this island was formed,
following in the footsteps of the geologists who have mapped
this island since the 19th century.
Now I'm heading offshore to explore the island's marine environment
with 21st-century technology.
So Eoin, how does seabed mapping work?
What's the process and how has it changed over the years?
Some of the areas that we're mapping now, the last time they were mapped
could have been in the mid to late 1800s. Wow!
And the technology in use at the time would literally
have been a length of rope with a weight on the end made of lead.
And they would have lowered that over the side of the vessel
and measured out how much rope they paid out until it hit the seabed
and that was their depth.
Whereas now, with a vessel like this, the RV KIRI,
we can actually map the whole seabed in 3D.
The sonar below the vessel sends out a big pulse of sound.
It could be up to 50 times a second,
depending on how shallow the water is. OK.
And that pulse is split into hundreds of beams.
And at the end of each of those beams, we get a depth reading
and the computers can put all of those depth readings together
very quickly and actually make a full 3D map of the seafloor.
We can get down to imaging an object 25 centimetres across. Amazing!
As the sonar is scanning, the data is actually appearing in real time
on the screen, almost like a computer game where we're painting
in the seabed.
Quite a serious game, because if we stray off our course at all,
if we lose focus, there are very dangerous rocks
just off to the side.
But because the sonar, as you can see there, is able to look sideways
as we come back on the next track, even closer to the land,
we can see what hazards might be awaiting us.
So you can see there from the deeper blue colours into the greens
and the yellows, you can actually see the shape of the seabed
and the rocks as it's getting shallower. Beautiful!
So every little bump and lump...
That's a boulder or a rock on the seafloor.
They're just beautiful, aren't they? It's really nice imagery.
And also, we're seeing it in high detail for the first time ever.
How much of a game changer is this tech, then?
It is a huge game changer in terms of seafloor exploration.
It's been around now for a couple of decades, but in recent years,
it's really come into its own and become far more accurate and able
to produce really crisp and more detailed images.
Every year, we resurvey some of the famous shipwrecks
around the Irish coast to test the equipment,
and we're getting more and more detailed imagery
with the passage of time.
So what's gained above the waterline?
What's gained below it? Both complement each other?
The thing about geology on land is it is obscured most of the time
by forests, grass, farmland.
So the great thing about the geology and the sea is,
while we can't easily get down and touch it,
it's far more exposed than on land because of wave and current action
that's stripping away the top cover.
The ultimate goal is if we can join the two together.
I'll give you a really good example is in Galway Bay,
you've got the limestone of the Burren on the Aran Islands
and on the Clare Coast, and on the north coast of Galway Bay,
you've got the granite of Connemara.
And for decades, people were trying to find the connection
between the two. But once we came along and mapped this,
we were actually able to see in clear detail,
just by looking at the texture,
the change from the limestone, which is very well layered,
to the granite, which is much more of a mass of rock.
And you can see it clear as day now on the imagery.
These cutting edge maps have many more practical uses,
including providing important information
about the location of some of Ireland's precious marine life.
Different species of fish and shellfish need specific habitats
for spawning, and this mapping helps to identify these crucial
areas for conservation.
How thrilling is it for you as a geologist to see this
for the very first time in this amount of detail?
Probably a little too excited, according to most of my friends!
But very excited! Are you geeking out, Eoin?! Sure.
This is a super geek out moment for me because it is true discovery
in the best sense of the word.
You're seeing something for the first time.
Some of these might have been seen by divers
or fishermen would have picked up some of the detail
on their own fish finders.
But this kind of blanket mapping where we're imaging
the entire seabed and giving it to the public for free,
it feels really good to be doing it.
Hidden in the dark, cold depths of Ireland's seas
lie the secrets of a rich seafaring past.
Over 18,000 shipwrecks have been documented in Irish waters,
and these relics can offer fascinating insights
into the processes at play in our oceans.
So, Charise, how long have you been mapping shipwrecks?
Well, I started working with the project in 2007, Liz,
but prior to that, the project had been mapping shipwrecks
since about 2000, 2001 and 2. OK.
So what we've done is, today, we've just mapped this particular
shipwreck here, which is the Manchester Merchant in Dingle Bay.
What are you discovering about this particular wreck?
So this particular wreck, the image here you'll see
on the right-hand side here, this is from about ten years ago. Right.
And what we did then in 2019 was
we surveyed the wreck in this extreme detail.
Look at the difference!
And then what we've discovered in the image ten years later
is actually there's been a change in this shipwreck on the seabed.
You'll see that one of the boilers has been displaced in the centre
of the shipwreck. Yeah.
And also, you can actually see now that it's become more exposed
and you can see all of the structures from the shipwreck
are now visible to us here. Absolutely.
So it's not just because of the accuracy of the technology now,
it's also due to wave action, currents, etc. For sure.
Everything changes down there. Exactly.
And why is that important to know?
It's like a time capsule.
Shipwrecks which are over 100 years old are protected.
So they're a really important part of our marine heritage.
And also, they can give indication, then, of the intensity of storms.
And we can use shipwrecks to look at scours on the seabed,
to look at the currents and how those currents are changing.
So it links to, you know, issues like climate change
and also oceanography and various other things.
What fascinates you the most about this kind of work?
I think for me, with the shipwreck side,
it's the human connection to a shipwreck.
You can see what that ship was about, why it was built,
what it was doing at the time of its sinking.
There's a number of shipwrecks around the coast of Ireland
that are graves. You know, that souls were lost on them.
And then there's a lot of communities around the coast
of Ireland that have a very close link to a particular ship
that may have sank off their coast.
There's a kind of a romance attached to shipwrecks, isn't there, really?
Oh, absolutely.
It's something that this story of the time that this ship went to sea.
So this particular ship had just been...come out of being used
in the Boer War, and it was then going back into a transit
across the Atlantic.
Unfortunately, it was carrying a cargo of cotton and turpentine.
And this spontaneous combustion
with kind of an inexplicable fire occurred.
So obviously the crew had to go into a panic.
You know, what would we do? We would try and put this fire out.
They tried to put the fire out. Unfortunately, they weren't able to.
And they obviously all made it to lifeboats.
And then, unfortunately, it met its fate and sank.
But there's a story from the other side of that, then,
where the captain of this particular ship
was so grateful to the local people around here,
they donated the bell from the ship to the church in Annascaul,
which is the home of Tom Crean.
So you've got that whole maritime link and the community link.
Fantastic stuff.
And we're right over it here, are we?
Yeah, we're just right over it here. 11 metres below us. 11 metres below?
It's not even that deep. It's not, no, not at all. Yeah.
Ireland may seem relatively small,
but when its seabed territory of 880,000 square kilometres
is taken into account,
it's actually one of the largest countries in Europe.
It's been said that more is known about the surface of the Moon
than of our ocean floors.
But this claim doesn't hold true for Ireland, which is on track
to become the first country in the world
to map its entire ocean territory.
This is the real map of Ireland,
with the red line marking the marine territory boundary -
an area more than ten times that of the land.
Ireland has embarked on
what is probably the largest contiguous
mapping exercise done by any state.
There are other countries that have built up data which will be
of similar size and that.
But because we've systematically done it in one full area,
it means that we have been able to use the most modern technology
and do it in a systematic way, which means that putting it all together
afterwards gives you a much better overall picture.
It was an Irishman, Piers Gardner, who developed the accepted formula
for establishing the outer limits of a state's continental shelf
until it tapers off into the abyss.
The mapping is all done by vessels such as the Celtic Voyager here,
and the Celtic Explorer, which spent almost two years going out to sea
and mapping in depths up to 4,000 metres of depth.
There's no visual images.
However, the interpretation of the sonar gives you...
It's very much like an ultrasound that you see in the hospital.
And it's that sort of imagery that's indicative of what's there.
It's not a real image, but it's a sonar return.
Stretching 200 nautical miles from the coastline is Ireland's
continental shelf, where the land extends under the sea
to the outer edge of the continental margin beyond.
It's a very different world down there.
What's really fascinating about going to the ocean
is the amount of discoveries that you can make there.
But it is hard, it is rough. You get seasick.
You're often kilometres away from your study area.
So there are challenges.
But I think the rewards are just obvious in terms
of this wonderful environment that we have on the seabed,
that's just a wonder to observe and to understand.
Ireland's deep ocean is home to massive cold water coral reefs
hundreds of metres tall, living in complete darkness and feeding
on organic matter that rains down from the surface.
And then there are canyons
that dwarf any geological features on the land.
Submarine canyons are big.
That's probably the best way to describe them.
And they start from the shelf break with about 200 metres' water depth
and go all the way down to the deep ocean, maybe five kilometres down.
And they're vast systems,
Grand Canyon-esque kind of scales.
And rather than just draining a river
that a terrestrial canyon would drain,
these also transport water and sediment and carbon and nutrients
down from the surface waters into the deep ocean.
So a real connection between the deep ocean,
the deep reservoirs of ocean, and what's happening on the surface.
They're very important in understanding how oceans
overturn and interact.
In 2011, just beyond Ireland's territorial waters,
an Irish-led research team
discovered huge hydrothermal vents rising out of the ocean floor.
Up to 60 metres in height,
they emit plumes of scalding hot water, harking back to the processes
that helped to form the island over the past 1.8 billion years.
So these are places where we've got volcanic activity,
where the plates are pulling apart.
And this volcanic activity is heating sea water.
It's pumping through the crust,
becoming mineralised and forming these black smoker chimneys.
So this is a sample here
of a piece of one of the black smoker vents.
And hot fluid, several hundred degrees C,
would have flowed up from the subsurface.
And when it hit the sea water, it becomes quenched and cools down.
And all the minerals, all the elements that have been solution
mineralise to form these black sulphide deposits.
You can see where one of the vents was, but there's various minerals
in here and on the back, you can see it's rusting.
So there's iron.
The white area is anhydrite
because this was very, very hot sea salt.
And in the greyish, greenish-greyish areas, these are metal sulphides.
And there's various metals of zinc and copper and lead.
Since they were first discovered in 1977, deep sea hydrothermal vents
have sparked great debate.
One school of thought is that black smokers might be the birthplace
of all life on Earth.
They support bacterial communities, called chemosynthetic bacteria,
and they get their energy from chemical reactions
going on in these black smokers.
So they have an energy source completely independent of sunlight.
So all other life on the planet
is, in some way, dependent on the Sun.
The Sun creates the plants, we eat the plants,
we eat the animals that eat the plants.
If the Sun went out tomorrow,
the whole life on the planet would die,
apart from at these black smokers.
And that's very intriguing, because that means
that if we have hydrothermal systems on other moons,
perhaps under thick ice caps on Europa or somewhere like that,
we may have a system of life similar to those black smokers.
So there's a lot of interest in that.
From Ireland's intimate connection to water
to the point in its history when life began to flourish,
the next chapter will trace the story of life,
from the remains of its first residents preserved in the rocks
to the arrival of humans and beyond,
and will explore the geological changes that lie ahead
for the island.