Original subtitles

Ireland.

The most westerly country in Europe.

An outpost in the North Atlantic,

it is the final landfall for thousands of miles,

and towers above the sea.

You have the ocean, the sky, the light,

the wind even in your hair.

You couldn't be closer to nature than here.

Here, land and sea clash endlessly.

The rock of Ireland, bitten and scoured by glaciers,

is constantly being shaped and reshaped by water:

pounding waves below, and driving rain from above.

It's a very dynamic landscape.

It's very rugged.

It evolves day and daily.

From the rugged Antrim coast, to the Wild Atlantic Way,

this is Ireland.

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The Cliffs of Moher, a steep and sweeping precipice

on Ireland's jagged west coast.

The cliffs tower more than 700 feet above the stormy Atlantic

and present real danger to those that fail

to heed its warning signs.

In the year 2000, two experienced climbers died

and another was gravely injured when rocks above them gave way.

And in 2015, a visiting photographer

captured a spectacular rock fall in progress.

It won't be the last time that these stunning cliffs

crumble into the ocean, piece by piece.

A powerful reminder that the geological violence

that built Ireland is still very much alive here.

But despite their many rock falls,

the Cliffs of Moher aren't disappearing any time soon.

They have stood here, in one form or another,

for more than 300 million years, and greet visitors today

coming east across the Atlantic.

The Cliffs of Moher extend for five miles

along Ireland's Wild Atlantic Way:

a spectacular coastal route that winds

for nearly 1,600 miles from Derry in the north

to Cork in the south.

The Cliffs of Moher draw close to one million visitors

each year.

This is one of the country's most breathtaking panoramas.

The cliffs provide shelter for more than 30,000 birds

from 29 different species.

But the land on which they roost began to accumulate

long before birds had evolved.

Long before even their ancestors, the dinosaurs,

had appeared on the planet.

What you're looking at there is a cross section through time.

You can see how the sediments have changed from the base

right through the top.

You can see each successive layer.

The Cliffs Of Moher are the remains

of an ancient river delta.

Land created as flooded rivers dumped silt, sand, and mud

into a shallow tropical sea.

This sediment accumulated layer upon layer

for millions of years.

Those sediments are getting shallower and shallower

because more and more sediment is pouring out and building out

and making, essentially making land.

Each of those layers may represent one storm event

or one massive flood event.

The fine shale layers then represent longer periods of time

where sediment has collected more slowly over time

then the next flood event will come along.

New sediment deposited on top created crushing pressure

on the sediment layers below,

compacting them into the solid rock we see today.

Over millions of years, earth's shifting tectonic plates

carried these sediment deposits north

from their point of origin south of the equator.

But the story doesn't end there.

Repeating layers of sandstone, siltstone and shale

provide a clear view of an ancient sedimentary basin,

something usually found underwater.

Now above land, the Cliffs of Moher

reveal their history inch by inch.

This geological treasure has only been made visible

by the constant, clawing waves at the base of the cliffs.

Those waves come in, they will undercut the base of the cliffs,

especially the shaley bits that will weaken it.

And parts will fall into the sea.

The clear shale, those dark, very dark rocks

they've got fossils in them,

they've got bits of plant material,

they've got goniatites, but not much,

they don't have the same variety of fossils

that we get in the limestone.

So it was a very difficult environment

for things to live in.

You've got rivers flowing on a swampy, marshy area

and we get evidence of that from lots of tree material.

We even find the roots of those trees in some of the sections

so we know there was plants growing on essentially soil

in that area.

Just offshore, Branaunmore, a 220-foot-high sea stack,

stands like an ancient guardian.

The sea stack is a remnant actually

of where the cliffs used to be.

The Cliffs of Moher are eroding backwards.

Due to these joints, due to the shaley nature of the cliffs,

and mostly because of these fantastic waves that are

coming in from the Atlantic pounding it every year.

Those promontories can get isolated so either side of them

will get eroded away more and eventually they get eroded away

at the back.

And that, sometimes they'll form arches initially and then those

arches will collapse and be left with a sea stack.

The rate of recession for the Cliffs hasn't been measured.

But on the nearby Aran Islands the cliffs recede

more than a foot-and-a-half each year due to erosion

caused by battering waves.

The Branaunmore sea stack is a reminder

that nothing set in stone will remain forever.

By the waves it was created.

By the waves it will be consumed.

Over time that sea stack is going to be eroded

and that sea stack will fall and collapse into the sea as well.

They come and then they go.

There'll be new ones forming long after we're gone.

The Cliffs of Moher.

Not quite eternal, but immortalized in films

such as The Princess Bride

and Harry Potter and the Half-Blood Prince.

And no wonder:

they're a special effect 300 million years in the making.

Eight miles north of the Cliffs of Moher in the region known as

The Burren is the Ivy Cliff Cave, or as it's known today:

Doolin Cave.

Doolin Cave formed like every other cave in the Burren.

It's on the limestone, so there was groundwater,

there was water flowing,

slightly acidic water, and over time

that just eroded channels within the rock and the limestone.

Hidden 80 feet beneath the entrance to Doolin Cave

is its prized treasure: the Great Stalactite.

At 23 feet, it is one of the longest

free-hanging stalactites in the northern hemisphere.

Limestone stalactites form as slightly acidic rainwater

seeps through the bedrock, dissolving and eroding

the minerals as it flows.

Where water drips from the roof of a cave, dissolved limestone

in the water precipitates out and hardens as calcite.

Over time, minuscule amounts of calcite build up,

eventually forming giant solid deposits

that appear to drip from the cave ceiling.

In most caves you'll get single, small, straw-like stalactites.

They're quite common.

It started forming almost certainly in the same way

as all the others, but the water continued flowing there

for a longer period of time.

The Great Stalactite is a dramatic example

of the geological processes that shape Ireland.

It was created over hundreds of thousands of years,

literally one drip at a time.

But Doolin Cave and its remarkable stalactite

are just one small feature in the Burren landscape.

The Burren comes from the old Irish word bhoireann,

which means rocky place.

This rocky place, comprised of nearly 100 square miles

of spectacular, rolling hills,

was formed some 350 million years ago.

It is a limestone pavement: layer-upon-layer

of calcium carbonate sediment that was once at the

bottom of the ocean, deposited by the skeletal remains

of ancient marine organisms.

The sea life that formed this pavement once lived in the

same tropical sea, fed by the river that helped give rise

to the Cliffs of Moher.

The rock of the Burren was compressed and hardened

by the weight of successive layers of calcium carbonate.

This sea floor once occupied a place much farther south,

at the same latitude where Egypt is today.

As tectonic plates moved, these rocks drifted north,

landing here when an ancient ocean closed

and two plates of crust collided,

forcing what was the seafloor to emerge high above the waves.

In the south-eastern part of the Burren,

an arresting 560-foot-high limestone hill

bears the twists and bends of a landscape

that was once under extreme pressure.

It is Mullaghmore.

In Irish, it means Great Summit.

There's irregular curved folds in the limestone there

and that's a result of compression.

That's the result of a continent sliding along

the surface of the earth, hitting another continent,

the rocks buckle and they folded, nice and gentle.

But this was far from the end of the geological story

for this new piece of land.

What is now Ireland was subjected

to the unrelenting chill and crush of glaciers.

This area has been subject to glaciation.

Like most of Ireland it was covered by ice at some point.

And once the ice travelled mostly from the north, northeast,

it scraped off the surface, scraped off any soil

that was there, and it exposed bare limestone.

The last glacial period to affect the Burren

ended 14,000 years ago.

But while the landscape may have been scraped bare by ice,

the land itself is far from barren.

That then got colonized slowly afterwards by initially grasses

and then more advanced trees and bushes.

And then when humans came along, around about 5,000 years ago,

they started cutting those trees down.

The hunter-gatherers that cut down great swaths of forest

for timber also raised cattle that devoured grasses,

contributing to the current stark landscape.

In 1651 an English Army Officer described the Burren as:

"A country where there is not water enough to drown a man,

wood enough to hang one, nor earth enough to bury them.

And yet their cattle are very fat."

Wildflowers and grasses take root in cracks and crevices in

the limestone and flourish in the Burren's sweet, damp air.

It's got grasses, it's got shrubs, it's got a fantastic mix

of alpine and Mediterranean flowers.

People come from all over the world to see that together

in the same place, and it's not the Arctic and it's not

the Mediterranean: it's in the west coast of Ireland.

But underneath the surprising plant life

there's the limestone, scrubbed and scratched by ice,

stripped and depleted by man, and now eroded by water.

Once this limestone has been exposed to the surface

what happens is rain will fall on it,

and we get a significant amount of rain here in the Burren,

and that rain is very slightly acidic,

a natural acidity from the carbon dioxide in the air,

and when that hits the limestone it will start to dissolve it.

This process creates what is known as karst topography.

The limestone of The Burren

is laced with a network of fissures called grikes.

These fissures isolate blocks of stone

at the surface known as clints.

The irregular pits, the hollows, the curves, the grooves

they're all a result of water flowing onto the surface

and flowing maybe under the soil as well

where it dissolves even further.

As the limestone bedrock slowly breaks down,

grikes grow wider and deeper, more water flows through them,

and the grikes continue to grow larger.

There are these fractures or joints all through the limestone

here in the Burren, also out on the coast,

and on the coast they're wonderfully exposed.

They are exposed as lines of weakness in the limestone.

About 20 miles from Mullaghmore, the cracked Doolin coast

looks almost man-made with its precise, sharp lines.

But it, too, is a result of the tectonic and erosive forces

that shaped the rest of the Burren.

We've got the water dissolving the limestone

very gradually over a long period of time.

On the coast it's much more dynamic, it's much more active,

and every year you go back there

you see the coast looks different.

Cracks in the rock bear witness to the tremendous force

generated far below by the grinding of what are now

the North American and Eurasian continental plates.

This is two huge plates crashing against each other,

and when I say crashing that exaggerates a little bit.

This is a slow process.

A couple of centimeters a year these two continents

are pushing into each other.

But there's huge pressure behind that and this pressure

builds up, builds up in rock and eventually something will give.

Like miniature earthquakes, these rifts in the limestone

are the visible evidence of that tectonic pressure.

These might have been just like a millimeter, two millimeters

wide these cracks, they popped open right through

the whole Burren.

But even a mere fraction of an inch is enough for water

to exploit chinks in the limestone

as rolling Atlantic waves pummel the Doolin coast below.

These waves pack a huge punch.

They're coming right across the Atlantic.

And when it hits the rocks, especially at a high tide,

these joints, these cracks that we talked about,

are slightly open, the water whams against that.

It pushes in the air that's already in there

and it's like a pneumatic force pounding in against that rock.

And it can actually fracture the rock.

It'll fracture along lines of weakness already there.

That makes it more susceptible to be moved during that storm

or the next storm or subsequent storms.

The waves of the Atlantic are even powerful enough to move

entire blocks of limestone that have washed free from the shore.

The rocks are being in some cases flipped over

on top of each other, stacked up

into piles of large lumps of limestone by these waves,

and sometimes just dragged offshore and broken up.

It's a great way to look at

how the coast is actually eroding there.

While the west coast of Ireland offers dramatic cliffs

from which to gaze out over the tempestuous Atlantic Ocean,

the east coast rewards visitors with panoramic views of peaks

and glens steeped in rich history:

the Wicklow Mountains.

This is the largest area of continuous high ground

in Ireland: nearly 200 square miles

with an unbroken elevation of more than one thousand feet.

The entire region is the result of what's known as

an igneous intrusion: a massive geological event

that occurred about 400 million years ago.

The continental plates of North America and Europe collided,

generating tremendous heat that melted the rock,

which then rose as magma.

But without the fiery force of a volcano, the magma slowly cooled

without breaching the surface, creating a form of igneous rock

familiar to us all: granite.

This mass of granite forms the Leinster mountain chain,

the largest continuous area of granite in Ireland and Britain.

For centuries, man has quarried granite

from the Wicklow Mountains, but it's not the only product

of these beautiful hills and valleys.

As the rocks were subjected to intense heat and pressure,

they were effectively cooked,

changing form into what's known as metamorphic rock.

These rocks contain elements

such as lead and zinc, copper and silver.

They were concentrated into thin narrow veins of mineral ore.

They filled those cracks in the rock and concentrated

in specific kind of fractures so they then became a target

for miners in the 1800s.

They were a place where you could go in and you could

dig in a narrow tunnel to extract the lead ore.

It was a mining center of great importance in the 1800s.

For more than 150 years,

the Wicklow mountains were mined for their treasures.

There was even a brief gold rush in the 18th century

after nearly 200 pounds of gold were discovered here.

Today, the lead mines, closed for good in the mid-1950s,

sit abandoned in the Glendalough and Glendasan Valleys.

But long before miners began their excavations,

glaciers left their mark on the Wicklow Mountains.

During the Ice Age, layers of snow and ice accumulated,

growing heavier with each year.

Over time, the glacier slid down the mountainside,

carving out massive hollows and valleys between the peaks.

The glacier came down and scooped the rock

out of this valley and deepened it,

and then after all the ice melted away

the over-deepened valley was filled with water

and that's what's here now.

At the heart of the Wicklow Mountains is Glendalough:

the valley of two lakes.

Glendalough stretches for nearly two miles and is

one of Ireland's most popular tourist destinations.

It is an area of sublime natural beauty

and fascinating history: from miners and monks, to monsters.

The sixth-century monk St. Kevin is said to have

banished a monster from one of the lakes at Glendalough

after it harassed the locals and their livestock.

Upper Glendalough is a magnificent example

of a glacial ribbon lake, a long and narrow body of water

usually found in a trough formed by a glacier.

A normal river valley is a kind of a V-shape

but a glacial U-shaped valley is sculpted by ice

in a glacier going down and, as you can see behind us,

it's got steep sides, steep cliffs there,

and the valley floor is relatively flat.

To maintain water levels at Glendalough,

these glacial basins need to be fed,

and no glaciers remain today.

Mountain streams and rivers now feed these lakes

and provide drinking water for nearby towns.

The River Liffey, which runs through the center of Dublin

more than 50 miles away, begins its journey here

at the Liffey Head Bog.

Lots of rain, combined with poor soil drainage

provides the ideal environment for Wicklow's

signature ecosystem: the Blanket Bog.

A blanket bog is what coats the mountain plateau here.

It's a kind of plant structure

that's growing in a waterlogged soil on top of the rock.

Moss grows in that and it forms this layer a meter or two thick

over the upland areas and it's a very

specific kind of plant community.

The blanket bog, and the moss that dominates it,

draw nutrients from rainfall to create an environment

that's highly acidic, poor in nutrients and low in oxygen.

Only certain plants can tolerate such a hostile setting,

making the blanket bog a highly specialized ecosystem.

As as the sort of living layer keeps growing up,

the bottom bits die away.

But because they're waterlogged, they form this layer of peat

which is a low-energy carbon fuel.

And people used to dig that in the past.

If you're on those upland areas, you see these sort of trenches

where people have extracted peat.

For centuries, people in the mountains cut peat for fuel

to warm their houses.

Today, just 28 percent of Ireland's original blanket bog

remains intact.

But now it's protected because it's an ecological community

that's very well represented in Ireland.

It's important to maintain because it's plant

and ecological diversity that you don't see in other, say,

upland areas in Europe.

Peat grows just a fraction of an inch per year

and can reach down for several yards.

The partially decomposed plant matter that forms a peat bog

can take thousands of years to accumulate.

It's a slow process, like the movement of tectonic plates,

the crush of glaciers,

and the building of a bridge to Scotland.

According to Irish legend, the amazing rock formations at the

Giant's Causeway on Northern Ireland's Antrim coast

are the remains of a bridge built by the giant Finn McCool.

He built it for a showdown with his rival,

an oversized Scottish rogue named Benandonner

who lived across the North Channel in Scotland.

Or so some would have you believe.

The Giant's Causeway is more than rocks.

I have listened to stories about a giant called Finn McCool

all my life.

And I've been working here for 30 years.

I've been sharing them stories with visitors

virtually all my life.

It's easy to imagine why early inhabitants would credit

a mythic giant with the creation of this extraordinary setting.

But the 40,000 interlocking basalt columns

of the Giant's Causeway were actually formed

by a volcanic event more than 50 million years ago.

Deep below the surface, shifting tectonic plates

forced massive volumes of molten rock through fissures

in the surface to create layers of basalt rock.

Wind, rain and waves carved a valley.

More volcanic eruptions followed.

Lava flowed quickly in thick streams.

The valley filled up with lava until it was 100 meters deep.

It was 1,200 degrees Celsius.

And it's like everything.

If you boil a kettle it will cool down.

The pool of lava had to cool down.

Lava at the bottom of the valley cooled slowly.

Then, like mud in a shallow pond on a hot day,

as the lava cooled it contracted and cracked in even patterns.

During the Ice Age,

glaciers scraped away at the top layers of rock.

When the ice retreated, sea levels rose,

and pounding waves wore away at more rock.

Variations in the rate of cooling

produced the honeycomb-like monument that stands today.

Columns can reach 39 feet tall.

While the solid lava deposits in the cliffs

measure more than 90 feet thick.

High seas pound the rocks of the Giant's Causeway.

Ireland is known for its volatile weather,

and here on the north-east coast,

sea mist can roll in quickly.

Navigation can be treacherous,

and ships need to steer clear of the rocks.

The coastline that surrounds Giant's Causeway

has caused many wrecks.

In 1588, more than 1,000 seamen died when a

Spanish military ship loaded with treasures sank here.

Today, these formations

also go by the name Spaniard Rock.

There are many versions of the legend of the Giant's Causeway.

Some say Finn destroyed the bridge he built.

Others say the Scottish giant destroyed it.

But no one disputes why the legend arose in the first place.

Eighty miles across the North Channel,

on the Scottish island of Staffa,

there are basalt columns

identical to those found on the Giant's Causeway.

The columns at Staffa are part of the same lava field

that built the Giant's Causeway,

and have fueled its long-standing legend.

The Giant's Causeway has been a tourist draw for 300 years.

More than half a million people visit each year.

It is the by far the most popular tourist attraction

in Northern Ireland.

Geological studies here have contributed greatly

to our understanding of basaltic volcanism.

In 1986, the Causeway was declared

a UNESCO World Heritage site.

Today it's owned and managed by the National Trust in the UK,

to protect this iconic segment of Irish heritage

for future generations.

When this site was actually privately owned,

the site was quarried.

There was a serious lot of stones took off it.

The National Trust bought the site.

When they bought the site all that stopped.

You know, no more stones left the site.

A good thing, too.

No one wants a giant at their door

looking for his stolen rocks.

Some rocks near the Causeway, carved by millions of years

of erosion, resemble elements of Finn McCool's world:

the Chimney Stacks,

the Organ,

and the Giant's Boot.

The Boot is one of the most popular features

on the Causeway.

Based on the size of the boot, it's estimated that Finn

would have been more than 50 feet tall.

It's a boot.

You know, it's the shape of a boot.

I believe it's a boot.

I believe the giant Finn McCool left it there

for us to have a look at.

It's a size 93 and a half.

A geologist would totally disagree with you.

The same period of extreme volcanic activity

that created the Giant's Causeway also gave rise

to Slieve Gullion 100 miles to the south.

Slieve Gullion is known as the most mysterious mountain

in Ireland.

And it's got lots of myths and legends associated with it.

And it's the eroded heart of a volcano.

More than 60 million years ago, volcanic turmoil far beneath

the surface caused the original Slieve Gullion volcano

to collapse into a great chamber far below.

The magma in this chamber

slowly cooled to form the solid granite seen today.

Surrounding the volcano was a circular fracture in the rocks,

seven miles in diameter.

Magma rose through this crack and cooled,

forming what's known as a ring dyke,

leaving a circle of hills around Slieve Gullion,

known today as the Ring of Gullion.

The landscape here has been designated

as an Area of Outstanding Natural Beauty,

and is home to a vibrant floral community.

Slieve Gullion is designated as a special area of conservation.

This heather is very, very special.

We've got ling heather and bell heather.

You can still see the lovely purple shades up the mountain.

Tales of the Irish giant Finn McCool

dwell in Slieve Gullion as well.

The landscape has ignited the imaginations

of settlers old and new.

People here living nowadays, they draw inspiration

from the mountain and those myths and legends

and those characters in their past.

On a day like today whenever we do have that low-lying mist,

it's fantastic because we can see the peaks of the ring dyke

peeking through all that mist.

You can just imagine whenever those myths and legends

and those characters in the past were roaming around here

and it's very easy to see why this is one of the most

mystical mountains in Ireland.

The legend of Finn McCool extends from Slieve Gullion

in the east, all the way west to the Slieve League Cliffs.

At the base of the cliffs,

in the Grey Mountains of County Donegal,

two sea stacks - the Giant's Desk and Chair -

are said to be where Finn McCool

drew up his plans for the Giant's Causeway.

But there's more here than the office furniture

of an angry giant.

The big significance here I suppose

is the sheer size in the landscape.

So it's notable from the sea, so early mariners,

people coming to Ireland over the times, would've seen it.

It would've been a landmark for them.

The majestic cliffs of Slieve League

rise nearly 2,000 feet above the ocean.

They are the highest sea cliffs in Ireland,

twice as tall as the more famous Cliffs of Moher.

Their origins are just as remarkable.

About 200 million years ago, ourselves and the Appalachians

were all the one mountain system way down south of the equator

and over time the whole system moved up north

and divided apart.

Slieve League has been recognized as the official

landfall for the International Appalachian Trail.

These mountains are the trans-Atlantic,

geologic extension of North America's

Appalachian Mountains.

The rock here has been directly linked

to that on the east coast of Canada.

Our nearest neighbor in those times

would've been Newfoundland.

So you can see where the Irish connection

was in Newfoundland even way before the people were there.

The crashing waves below seem quiet from so high above.

And although Slieve League's steep face plunges straight into

the powerful Atlantic, erosion by waves has played

only a minor role in shaping this part of the coast.

Slieve League was carved not by water, but by glaciers.

This whole area here would've been under ice

maybe 70 to 100 meters deep and the ice has ground out

and very much shaped the cliffs.

We had thousands of years of ice here up until about

10,000 years ago at the end of the last ice age.

But right behind me here down in the cove there

with the Giant's Desk and Chair,

was a glacier there for thousands of years.

Research suggests that the ice sheet that covered Slieve League

may have been nearly half a mile thick.

Deep enough to encase the summit.

The enormous weight of that volume of ice would have

depressed the Earth's surface by as much as 650 feet.

Slieve League's dizzying slopes rise to the ridges and trails

used by hikers to traverse this natural wonder.

Leading to the summit is a trail known as One Man's Pass.

It is an arete, a knife-like ridge of rock

formed when two glaciers erode parallel, opposing valleys.

It offers breathtaking views for hikers with good balance

and nerves of steel.

Most people can cross the One Man's Pass.

But it's a section of the trail that's about a half mile long

that's only two foot wide.

You've a drop down to the ocean of over 1800 feet.

I always lean the other way,

it's only 1400 feet down to a wee lake.

Some people will crawl it, some people will walk it,

some people will pray on it.

The otherworldly majesty of Slieve League

has drawn and inspired giants and mere mortals alike

over hundreds if not thousands of years.

Some seek to connect with a higher power.

There's a Christian pilgrimage going on here

for almost 2000 years,

since the early Christian monks settled up here.

And these pilgrimages we know go back pre-Christian

and archaeological evidence will show us

that there was people living, or doing things

on these mountains way before Christianity.

The cliffs are also home to military installations built

to watch over the possible trespasses of a French Emperor.

These signal towers, the British built them here

from 1803 until about 1806 or 1807.

And they built a whole series of these

right around the coast of Ireland.

They were watching out for Napoleon.

The British were afraid he would invade Ireland, arm the Irish,

and then maybe chase them out and invade Britain.

So this system was set up -

an early watch system basically is what they are.

And they're still standing today.

Shaped by glaciers, the cliffs of Slieve League

are a breathtaking example of Ireland's natural beauty.

You couldn't be closer to nature than here.

You have the ocean, the sky, the light,

the wind even in your hair.

You can just get lost in nature.

You couldn't be in a better place.

Ireland: small in size, but epic in wonder.

Its vistas and wild spaces are fit for ancient, mythical heroes

and 21st-century explorers.

It is surrounded by the sea,

yet tied to other lands far across the ocean.

Here, rock and water are locked in constant struggle,

keeping the Earth in a state of flux,

ensuring that nothing is set in stone forever.

Ireland's mountains and cliffs, its valleys and lakes,

will continue to rise and fall with the passage of time

on a scale far beyond the realm of mere mortals.

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