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Earth, a 4.5- Billion-year-old planet,
still evolving.

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As continents shift and clash, volcanoes
erupt, glaciers grow and recede,

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the Earth's crust is carved
in numerous and fascinating ways,

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leaving a trail of
geological mysteries behind.

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In this episode, Loch Ness, in
the Highlands of Scotland, is explored.

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It holds more water
than any other lake in Britain,

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with a bedrock containing some
of the oldest rocks on the planet.

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Set in a landscape that was
once part of America,

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Loch Ness is a lake with an
enduring myth, the Loch Ness monster.

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A team of scientists investigate
how Loch Ness was made.

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The clues they uncover
also provide a window

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into the formation of the Earth itself.

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Deep, dark and full of mystery.

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This is Loch Ness
in the Highlands of Scotland.

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For a thousand years, there
have been claims that this vast lake

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hides a strange and terrible secret,
the fabled Loch Ness monster.

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A mythical beast, suggested by some
as a descendant of the dinosaurs

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which once roamed
this part of Scotland.

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Loch Ness would be the perfect
hiding place for a prehistoric monster.

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At 23 miles long, and a mile wide,
this vast freshwater lake

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covers the same area as
New York's Manhattan Island.

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And it's more than 700 feet deep.

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But the monster is not the only mystery
that surrounds Loch Ness.

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In the hills above the loch,
there is a type of rock

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whose origin baffled scientists for years.

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It's a sandstone,

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and it's the start of the investigation
into how Loch Ness was made.

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It's known
as the old red sandstone,

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and it's given that name
because it's red and it's a sandstone,

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and it's called old

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because
it's about 350 million years old.

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The old red sandstone runs down
one side of Loch Ness.

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But the most astonishing fact
about these rocks is not their age,

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but where they come from.

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These rocks actually belong
to my homeland of North America,

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because these rocks originated
on the North American continent,

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and then have separated
from North America.

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But in many ways this is almost a little
bit of home for me here in Scotland.

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But how do geologists know
that this old red sandstone

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comes from 3,000 miles away,
on the other side of the Atlantic Ocean?

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These rocks are identical
in age and character

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to the rocks that actually form
the Catskill Mountains,

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and so this part of Scotland belonged
to northeastern North America.

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For more than a thousand years,
old red sandstone has been used

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for building castles
in this part of Scotland.

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But it's also been quarried in the US

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and used for brownstone buildings
in New York City.

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Under the microscope,

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rocks from both continents
have an identical crystal structure,

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and chemical analysis has also proved
that they're exactly the same age.

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But how did part of America end up
on the shores of Loch Ness?

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To answer this crucial question,

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the investigation must go
much further back in time,

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to look for evidence in the ancient
bedrock of northern Scotland.

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It's here that the story
of Loch Ness begins.

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The trail starts north of Loch Ness,
where the bedrock comes to the surface.

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This landscape is full
of the extraordinary mysteries

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of an unimaginably ancient past.

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It's made of a type of rock
called Lewisian gneiss.

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Recent drilling and blasting for
a new road cut have exposed evidence

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which uncovers an amazing chapter
in Earth's history.

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The long straight lines are the drill holes
left in the rock face.

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Modern radioisotope dating
has given geologists the first clue

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to understanding the origin
and formation of these rocks.

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These rocks are very special
to geologists.

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They are some of the very
oldest rocks in the world.

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We see them in very few places,

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perhaps a dozen places across
the globe contain rocks of this age,

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talking about two and a half
to three billion years old.

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The origin of the grey Lewisian gneiss
lies in the first crust

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that cooled on the surface of the Earth.

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After its formation 4.5 billion years ago,
parts of this crust were mixed together

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with the earliest sediments,
buried, re-melted and forced back up,

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again and again,
for more than a billion years.

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These extraordinary rocks
are the result

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of that devastating period
in our planet's history.

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And there's more evidence
exposed in this road cut,

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revealing crucial information about the
early history of the Loch Ness region.

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This exposure contains

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three important pieces
of geological jigsaw puzzle.

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First, we have the grey gneiss,
2.5 to 3 billion years old.

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Secondly, we have
this black igneous material

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which has been intruded into the area.

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This is two billion years old.

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And thirdly, we have
this pink granitic intrusion

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that both intrudes the black material
and the gneiss,

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and this is 1.8 billion years old.

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This evidence reveals that after
the formation of the Lewisian gneiss,

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much younger rocks were then melted
and mixed into the ancient crust.

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But this process took
an incredible length of time.

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What we've got here

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are rocks that record over a billion years
of Earth history.

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Now, to put that into perspective,

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that is almost a quarter of the age
of the Earth recorded in this exposure.

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This is the bedrock of Loch Ness.

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It carries an extraordinary story
of a major part of Earth's history.

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And there are yet more secrets
hidden in these rocks.

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It looks very much because
of the temperatures and pressures

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that these rocks were under that they've
been to depths of perhaps 50 miles

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beneath the Earth's surface in the past.

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This suggests that these rocks
have been to hell and back

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two or three occasions
over a billion year period.

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Geologists now know that
the only force powerful enough

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to produce this extraordinary mix
of rocks is plate tectonics.

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Plate tectonics is the process by which
the giant plates of the Earth's crust

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are driven slowly across the planet's
surface by vast convection currents

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deep in the Earth's hot mantle.

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In the Loch Ness region,
the evidence in the road cut

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reveals that incredible pressures forced
the crust deep down into the earth,

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where it was melted, deformed,
mixed together,

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then finally brought back to the surface.

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After that, for another billion years, this
ancient land mass quietly eroded down

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to a rough, rolling landscape.

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But this wasn't the green terrain
we see now.

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There was much less oxygen
in the Earth's atmosphere than today,

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and the surface would have looked like
a lunar landscape - desolate and sterile.

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Incredibly, remnants of that billion year
old landscape are still preserved today.

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The clues are revealed
in another road cut,

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where the trained eye
can draw amazing conclusions

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from what looks like a jumble of rocks.

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At this road cut,
we can see Lewisian gneiss

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which is between two and a half
and three billion years old.

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But up here we have something
completely different.

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If I go up to this level
and look above it,

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we have horizontally bedded
red sandstones.

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This sudden change in rock type
helps to unravel the mystery

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hidden in these ancient formations.

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They're believed to have been laid down
in a continental environment by rivers.

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We've got river systems that laid down
horizontally bedded sedimentary rocks

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on an ancient landscape.

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So this simple outcrop reveals
that even in a world with little oxygen,

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the ancient bedrock of Scotland
was covered in rivers a billion years ago.

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And there's yet another
secret hidden here.

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There is a junction between these rocks
which are almost a billion years old

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and the rocks below that are two
and a half to three billion years old.

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This is a major time gap of between
one and a half and two billion years.

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The time gap revealed here
is extraordinary.

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It shows that after the traumas
of their early formation,

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the rocks of the Loch Ness region
went through a period of calm

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which lasted more than a third
of the age of the Earth.

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The investigation into how
Loch Ness was made

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has uncovered its first evidence.

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Identical old red sandstone
found on two continents

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proves that Scotland and America
were once joined together.

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Some of the oldest rocks in the world

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reveal that the bedrock
underlying Loch Ness

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was made during the primeval creation
of the Earth's crust.

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Bedded sandstones
lying on the ancient bedrock

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show that rivers flowed over
this landscape a billion years ago,

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during a long period of tranquillity.

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But the calm couldn't last forever.

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A major continental collision
was looming,

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and with it the union
between Scotland and England.

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The investigation
into how Loch Ness was made

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will next uncover
the geological structures

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which would eventually create
Loch Ness.

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The search for evidence begins
with a 19th-century scientific mystery.

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In the 1880s, geologists in Scotland
were baffled by a sequence of rocks

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they found north of Loch Ness.

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Here in a remote hillside
lay the problem.

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A huge mass of very old Lewisian gneiss
was lying on top of much younger rocks.

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But the 19th-century geologists
had never encountered this before.

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In their experience, younger rocks
always lay on top of older beds.

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Then, one scientist invented a novel
approach to try to solve the puzzle.

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A survey geologist back in
the Victorian age, 125 years ago,

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mapped this area
and his name was Henry Cadell.

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He went back to Edinburgh and he
worried about what he'd seen in the field

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and thought, "How do I replicate what
I've seen? How does this happen?"

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So he built a model and he attempted
then to show, using the model,

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what it was that he saw in the field.

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Cadell's model was simple.

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He suspected that some force
had squeezed the rocks horizontally

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to make this upside-down sequence,

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so he built an apparatus containing
layers of sand and clay to test his ideas.

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Professor Underhill is using
a replica of Cadell's equipment,

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filled with alternating layers
of black sand and plaster of Paris,

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to try and duplicate Cadell's experiment.

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Turning the screw
winds the block forward,

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imitating the horizontal pushing force
that Cadell thought was the culprit.

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As the horizontal force increases,
the layers are pushed over each other

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along a shallow plane which geologists
now call a thrust fault.

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And we've got
the first thrust appearing.

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Oh, look at that, another thrust going in.

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The experiment showed Cadell
exactly how older layers,

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the ones on the bottom,

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are pushed over and on
top of the younger layers

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along the plane of the thrust fault.

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There's some beautiful
structures in here,

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there's a thrust fault running through
here which duplicates the white layer,

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and another one through here
and the final thrust fault

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which is at the lowest angle,
out here towards the left-hand side.

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A success in terms
of a simple model

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replicating what we see on the ground,
and I can see how Cadell and others,

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when attempting such things,

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began to understand what it was
that they saw in the field.

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They could replicate it
in a simple, crude model,

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but replicate it
in a very successful manner.

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Once Cadell and his colleagues
understood the principle of thrust faults,

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the apparently illogical sequence of the
rocks they saw in northwest Scotland

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began to make sense.

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Well, the slope
represents a thrust fault.

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What we have underneath it is
a bedded younger quartzite succession

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which is pink.

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Above it, the grey rock,
the rubbly grey hillside we see above

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is the Lewisian gneiss again.

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And the surface in between,
which is putting older rock,

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the grey material, onto the pink rock,
the younger material,

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is the thrust fault, just like in the model
that we saw before.

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Geologists now know that a thrust fault
is the smoking gun

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that shows where
continents have collided.

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But which continents were colliding
to make the thrust faults in Scotland?

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And how were they involved
in making Loch Ness?

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The scientists' trail now led them
to another thrust fault,

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the Moine Thrust.

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00:15:03,807 --> 00:15:08,567
The Moine Thrust is one of
the biggest thrust faults on Earth.

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Running for 120 miles down
the northwest of Scotland,

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it's mostly hidden from view,

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but Professor Underhill
has found one of the rare locations

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where the thrust can be seen
on the surface.

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This apparently insignificant join
between two rock layers

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is the actual line of the thrust,
and it reveals a geological bombshell.

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The dark layer above the thrust
comes from England,

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but the surprise lies
in the yellow limestone below it.

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Just like the old red sandstone
at Loch Ness,

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this rock comes from North America.

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This one small piece of evidence
has enormous implications

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00:15:50,447 --> 00:15:53,527
for the formation of Loch Ness.

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The amazing thing about this contact

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is that it's the meeting point
between two continents.

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So here we are on a wet Scottish hillside
on a Sunday afternoon

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and I am touching
the contact between, effectively,

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00:16:04,887 --> 00:16:09,127
America and northwestern Scotland
on one hand, and England on the other

233
00:16:09,127 --> 00:16:12,244
as was 425 million years ago.

234
00:16:17,647 --> 00:16:21,487
But how did these two
ancient continents collide?

235
00:16:21,487 --> 00:16:26,847
450 million years ago, a supercontinent
containing North America and Scotland

236
00:16:26,847 --> 00:16:29,236
lay deep in the southern hemisphere.

237
00:16:30,247 --> 00:16:33,687
At its margin was an ocean wider
than the present-day Atlantic.

238
00:16:33,687 --> 00:16:36,967
On the other side was
England and Europe.

239
00:16:36,967 --> 00:16:39,567
But the forces
of plate tectonics

240
00:16:39,567 --> 00:16:41,047
were slowly pushing

241
00:16:41,047 --> 00:16:43,847
the two land
masses together.

242
00:16:43,847 --> 00:16:47,447
Well, around 450 million
years ago there was a major ocean

243
00:16:47,447 --> 00:16:48,807
where we're standing now.

244
00:16:48,807 --> 00:16:51,007
It was called the lapetus Ocean

245
00:16:51,007 --> 00:16:54,767
and it separated America
and northwestern Scotland on one hand,

246
00:16:54,767 --> 00:16:58,567
from, effectively, southeastern Scotland
and England on the other hand.

247
00:16:58,567 --> 00:17:01,527
Now, what happened
in the 20 million years after that,

248
00:17:01,527 --> 00:17:05,327
that ocean closed,
and eventually was closed sufficiently

249
00:17:05,327 --> 00:17:08,524
that two continents collided
into each other.

250
00:17:11,647 --> 00:17:15,287
The collision between America and
Europe pushed massive layers of rock

251
00:17:15,287 --> 00:17:19,647
over each other,
forcing upwards a range of mountains

252
00:17:19,647 --> 00:17:22,967
higher than the Himalayas are today.

253
00:17:22,967 --> 00:17:27,757
Still firmly attached to America, Scotland
and England became fused together.

254
00:17:29,807 --> 00:17:33,127
But what did this collision have to do
with the making of Loch Ness?

255
00:17:33,127 --> 00:17:38,047
The loch itself provides
the most fundamental evidence.

256
00:17:38,047 --> 00:17:41,087
The one thing that's quite
striking about Loch Ness

257
00:17:41,087 --> 00:17:43,767
is that when you look at it,
particularly from this perspective,

258
00:17:43,767 --> 00:17:47,047
you can see that it runs straight,
almost straight as an arrow,

259
00:17:47,047 --> 00:17:51,287
and that straightness
goes on for about 20 miles.

260
00:17:51,287 --> 00:17:55,167
And as a geologist, that tells me
that there has to be a control

261
00:17:55,167 --> 00:17:57,327
on this topographic straightness,

262
00:17:57,327 --> 00:17:59,807
because nature doesn't produce things
in straight lines.

263
00:17:59,807 --> 00:18:01,847
And so there is a structure here

264
00:18:01,847 --> 00:18:04,767
that is controlling the overall shape
of Loch Ness itself.

265
00:18:04,767 --> 00:18:10,207
This structure is the Great Glen Fault,
a major geological fault line

266
00:18:10,207 --> 00:18:14,485
formed during the continental collision
425 million years ago.

267
00:18:15,887 --> 00:18:19,927
It runs for more than 300 miles
right across Scotland,

268
00:18:19,927 --> 00:18:22,127
slicing the country in two.

269
00:18:22,127 --> 00:18:27,167
Loch Ness exactly follows
the line of the Great Glen Fault.

270
00:18:27,167 --> 00:18:31,087
The Great Glen Fault is not
a thrust fault like the Moine Thrust

271
00:18:31,087 --> 00:18:32,927
where material has been
pushed up over,

272
00:18:32,927 --> 00:18:38,240
it's not a normal fault where material
drops down vertically, it's lateral motion.

273
00:18:41,287 --> 00:18:45,207
The Great Glen Fault is Scotland's
version of the San Andreas Fault,

274
00:18:45,207 --> 00:18:47,687
it's just 400 million years older.

275
00:18:47,687 --> 00:18:50,447
The Great Glen Fault is no longer active,

276
00:18:50,447 --> 00:18:53,567
but this giant split
in the Earth's crust has been a feature

277
00:18:53,567 --> 00:18:57,727
of the Scottish landscape
for more than 400 million years.

278
00:18:57,727 --> 00:19:02,527
It's the foundation of Loch Ness,
and without it the loch could not exist.

279
00:19:02,527 --> 00:19:07,527
Nor could the legend of
the Loch Ness monster.

280
00:19:07,527 --> 00:19:10,087
The investigation into how
Loch Ness was made

281
00:19:10,087 --> 00:19:12,247
has uncovered more evidence.

282
00:19:12,247 --> 00:19:15,967
The discovery of thrust faults
showed geologists what happens

283
00:19:15,967 --> 00:19:18,327
when continents collide.

284
00:19:18,327 --> 00:19:21,967
Yellow limestone from North America
found at the Moine Thrust

285
00:19:21,967 --> 00:19:23,727
proves that America and Scotland

286
00:19:23,727 --> 00:19:28,647
crashed into England
450 million years ago.

287
00:19:28,647 --> 00:19:31,807
And the shape of Loch Ness
reveals the straight line

288
00:19:31,807 --> 00:19:36,323
of the underlying Great Glen Fault,
formed during that continental collision.

289
00:19:37,647 --> 00:19:40,407
After the collision,
the forces of plate tectonics

290
00:19:40,407 --> 00:19:45,087
drove Scotland south
round the surface of the Earth.

291
00:19:45,087 --> 00:19:49,524
Now the investigation must
follow its amazing journey.

292
00:19:53,087 --> 00:19:56,967
The next step in the investigation
into how Loch Ness was made

293
00:19:56,967 --> 00:20:00,047
traces Scotland's journey
round the surface of the Earth,

294
00:20:00,047 --> 00:20:02,847
driven by the forces of plate tectonics.

295
00:20:02,847 --> 00:20:07,767
Understanding what the environment
was like in the past gives clues

296
00:20:07,767 --> 00:20:11,157
to the location of Loch Ness
millions of years ago.

297
00:20:12,447 --> 00:20:17,647
So the investigation now moves on
to the Jurassic period,

298
00:20:17,647 --> 00:20:20,923
165 million years ago.

299
00:20:22,687 --> 00:20:28,607
The trail leads to the Isle of Skye, an
island off the west coast of Scotland.

300
00:20:28,607 --> 00:20:32,647
At Staffin Bay there is
an incredible piece of evidence

301
00:20:32,647 --> 00:20:35,727
which sheds light on this period
in Scotland's past.

302
00:20:35,727 --> 00:20:41,327
Astonishingly, it lay in plain sight
but undiscovered until 1994,

303
00:20:41,327 --> 00:20:45,367
when an amateur geologist
made an extraordinary find.

304
00:20:45,367 --> 00:20:49,527
On the flat, rocky shoreline
of this popular beach,

305
00:20:49,527 --> 00:20:54,203
he discovered a fossilised footprint
of a giant dinosaur.

306
00:20:58,127 --> 00:21:04,127
Dr Anjana Khatwa has come to analyse
the details of this remarkable evidence.

307
00:21:04,127 --> 00:21:07,127
When you walk across these ledges,
it's just an incredible feeling

308
00:21:07,127 --> 00:21:11,807
to think that dinosaurs walked on the
same ledge that I'm walking on now,

309
00:21:11,807 --> 00:21:14,647
165 million years ago.

310
00:21:14,647 --> 00:21:18,407
This ledge, we've got this
wonderful megalosaurus footprint.

311
00:21:18,407 --> 00:21:22,767
The megalosaur was
a 25-foot high carnivorous dinosaur,

312
00:21:22,767 --> 00:21:25,725
quite a formidable predator
during Jurassic times.

313
00:21:27,087 --> 00:21:28,207
(ROARS)

314
00:21:28,207 --> 00:21:32,287
With some individuals standing
as tall as a football goalpost,

315
00:21:32,287 --> 00:21:35,677
megalosaurus was a fearsome monster.

316
00:21:36,687 --> 00:21:39,607
But how could something
as temporary as a footprint

317
00:21:39,607 --> 00:21:42,997
be preserved for 165 million years?

318
00:21:44,207 --> 00:21:45,687
The footprints
are so unique.

319
00:21:45,687 --> 00:21:51,647
What's happened is that a dinosaur has
travelled over a kind of sticky gooey mud

320
00:21:51,647 --> 00:21:54,047
and their impressions
have been left behind.

321
00:21:54,047 --> 00:21:58,207
That mud has dried off and
it's hardened and then, over time,

322
00:21:58,207 --> 00:22:01,847
wind-blown sand has come in
and covered that footprint over

323
00:22:01,847 --> 00:22:03,847
and then as further time has developed,

324
00:22:03,847 --> 00:22:07,087
we get layers of clay and sand
building up over that footprint

325
00:22:07,087 --> 00:22:09,887
and that footprint becomes fossilised
over time.

326
00:22:09,887 --> 00:22:12,407
Now, over a few million years,

327
00:22:12,407 --> 00:22:17,927
erosion occurs and those footprints
become exposed for us to see today.

328
00:22:17,927 --> 00:22:21,367
Dr Khatwa is making a plaster cast
of one of the footprints

329
00:22:21,367 --> 00:22:24,279
so she will be able to examine it
more closely.

330
00:22:25,967 --> 00:22:29,727
We take the cast in order
to have a record of the footprints

331
00:22:29,727 --> 00:22:32,967
so we can take them back to the lab
and have a look at them and understand

332
00:22:32,967 --> 00:22:35,927
how this creature used to live.

333
00:22:35,927 --> 00:22:38,007
As she carefully removes
the plaster cast,

334
00:22:38,007 --> 00:22:43,327
its shape reveals
a 165-million-year-old secret.

335
00:22:43,327 --> 00:22:46,807
One thing that really strikes me,
actually, is the deep impression

336
00:22:46,807 --> 00:22:51,207
that this front toe has made,
and how pointed it is,

337
00:22:51,207 --> 00:22:54,847
and this tells me that this dinosaur
was moving at a fast speed

338
00:22:54,847 --> 00:22:57,567
and really pushing down
on its front three toes,

339
00:22:57,567 --> 00:23:01,640
so it might have been chasing
some kind of prey.

340
00:23:03,447 --> 00:23:06,087
(SCREECHING)

341
00:23:06,087 --> 00:23:07,847
But megalosaurus
wasn't the only dinosaur

342
00:23:07,847 --> 00:23:13,080
to leave its footprints in these rocks
only 60 miles from Loch Ness.

343
00:23:17,367 --> 00:23:22,527
This the smallest dinosaur footprint that
anybody has ever found in the world.

344
00:23:22,527 --> 00:23:25,247
You can actually see
it's about the size of my fingernail.

345
00:23:25,247 --> 00:23:28,447
And we think it's a coelophysis,
and it's quite interesting

346
00:23:28,447 --> 00:23:32,247
because the small footprint here,
which we think is from a hatchling,

347
00:23:32,247 --> 00:23:35,407
is embedded in the larger one
here that you can see.

348
00:23:35,407 --> 00:23:37,087
What we think this tells us

349
00:23:37,087 --> 00:23:39,767
is that the young travelled
with their parents in groups

350
00:23:39,767 --> 00:23:43,840
and that most probably that adults
were looking after the young.

351
00:23:45,927 --> 00:23:48,567
Geologists have used
the amazing evidence

352
00:23:48,567 --> 00:23:51,447
of the footprints of coelophysis
and megalosaurus,

353
00:23:51,447 --> 00:23:53,807
together with the muddy rocks
they were found in,

354
00:23:53,807 --> 00:23:58,927
to better reveal the story of Loch Ness
in the Jurassic period.

355
00:24:00,447 --> 00:24:04,087
At the time, Scotland was
still attached to America.

356
00:24:04,087 --> 00:24:08,687
Plate tectonics had driven this land mass
much nearer the equator,

357
00:24:08,687 --> 00:24:11,647
2,000 miles further south than it is now.

358
00:24:11,647 --> 00:24:16,567
And that had a major effect on the
climate and environment of Loch Ness.

359
00:24:16,567 --> 00:24:18,087
Back during
the Jurassic times,

360
00:24:18,087 --> 00:24:22,047
the climate and the environment was
very, very different to what we see today.

361
00:24:22,047 --> 00:24:26,327
There would have been lush jungles
full of tropical vegetation

362
00:24:26,327 --> 00:24:29,607
and the dinosaurs would have been
living on the edge of these jungles,

363
00:24:29,607 --> 00:24:32,127
travelling over lagoonal type
of wetlands.

364
00:24:32,127 --> 00:24:35,327
This climate was ideal
for dinosaurs to live in,

365
00:24:35,327 --> 00:24:38,767
because it supported
a huge ecosystem of wildlife

366
00:24:38,767 --> 00:24:41,235
that they would have predated on.

367
00:24:43,287 --> 00:24:45,127
The bones of one more dinosaur

368
00:24:45,127 --> 00:24:47,887
have recently been found
on the Isle of Skye -

369
00:24:47,887 --> 00:24:50,321
the plesiosaur.

370
00:24:51,807 --> 00:24:55,846
But this discovery generated
a completely different kind of interest.

371
00:24:58,647 --> 00:25:02,607
Enthusiasts see a strong resemblance
between the shape of the plesiosaur

372
00:25:02,607 --> 00:25:05,565
and some descriptions
of the Loch Ness monster.

373
00:25:08,247 --> 00:25:10,647
Could a descendant
of the long-extinct plesiosaur

374
00:25:10,647 --> 00:25:13,847
really be the source of the legend?

375
00:25:13,847 --> 00:25:15,767
(GROWLS)

376
00:25:15,767 --> 00:25:18,847
The evidence to unravel the
extraordinary geological history

377
00:25:18,847 --> 00:25:21,007
of Loch Ness is getting stronger.

378
00:25:21,007 --> 00:25:25,167
The findings of megalosaurus
and coelophysis footprints

379
00:25:25,167 --> 00:25:30,527
prove that dinosaurs lived in Scotland
165 million years ago,

380
00:25:30,527 --> 00:25:33,807
and that Loch Ness was then
a sub-tropical paradise,

381
00:25:33,807 --> 00:25:37,287
2,000 miles further south
than it is today.

382
00:25:37,287 --> 00:25:39,367
But about 60 million years ago,

383
00:25:39,367 --> 00:25:43,047
five million years after
the dinosaurs became extinct,

384
00:25:43,047 --> 00:25:47,404
plate tectonics would tear
Loch Ness and America apart.

385
00:25:55,487 --> 00:25:58,407
The investigation into how Loch Ness
was made

386
00:25:58,407 --> 00:26:01,927
now moves forward to a time
60 million years ago.

387
00:26:01,927 --> 00:26:05,727
Scotland and America
are still firmly joined together.

388
00:26:05,727 --> 00:26:11,359
The next question is, when and how
did they become separated?

389
00:26:13,047 --> 00:26:16,167
On the Isle of Skye,
the landscape is full of evidence

390
00:26:16,167 --> 00:26:21,002
which can unlock the secrets of this
turbulent period in Scotland's past.

391
00:26:23,047 --> 00:26:27,367
At Talisker Bay, the massive
sea cliffs provide the first clue

392
00:26:27,367 --> 00:26:29,567
to the events that devastated the region.

393
00:26:29,567 --> 00:26:33,047
They're made entirely of volcanic lava.

394
00:26:33,047 --> 00:26:35,207
I'm standing here on a single lava flow,

395
00:26:35,207 --> 00:26:38,127
and this lava flow
is only about ten feet thick.

396
00:26:38,127 --> 00:26:44,847
But this whole cliff above me is made up
of lava flows, maybe 150 feet or more,

397
00:26:44,847 --> 00:26:48,207
and stretching for miles in all directions.

398
00:26:48,207 --> 00:26:51,007
Now, these lava flows
are composed of basalt,

399
00:26:51,007 --> 00:26:55,527
that's the same type of rock
that is being erupted today

400
00:26:55,527 --> 00:26:58,883
from modern volcanoes
like Hawaii or Iceland.

401
00:27:03,607 --> 00:27:07,927
Geologists have calculated
that these basalt lavas on Skye

402
00:27:07,927 --> 00:27:10,527
are about 60 million years old,

403
00:27:10,527 --> 00:27:13,758
but where is the volcano
which erupted them?

404
00:27:15,647 --> 00:27:20,127
The clue comes from a range of
mountains on the southern tip of Skye,

405
00:27:20,127 --> 00:27:22,887
the Cuillin hills.

406
00:27:22,887 --> 00:27:25,607
It's the type of rock that
makes up these craggy peaks

407
00:27:25,607 --> 00:27:28,447
which provide the evidence.

408
00:27:28,447 --> 00:27:31,047
They're made
of a rock called gabbro.

409
00:27:31,047 --> 00:27:34,087
Now, these are
the same chemical composition

410
00:27:34,087 --> 00:27:37,167
as the basalt that's been
erupted on to the surface,

411
00:27:37,167 --> 00:27:38,727
but there's a difference.

412
00:27:38,727 --> 00:27:42,527
The basalt that was erupted
was cooled very quickly

413
00:27:42,527 --> 00:27:44,487
because it was exposed to the air.

414
00:27:44,487 --> 00:27:47,127
Geologists call that fine-grained.

415
00:27:47,127 --> 00:27:50,247
On the other hand,
the magma that was trapped

416
00:27:50,247 --> 00:27:54,047
maybe a mile down beneath the Earth's
surface, that cooled pretty slowly,

417
00:27:54,047 --> 00:27:56,407
it was kept warm
for quite a long time,

418
00:27:56,407 --> 00:27:58,527
and so you've got
very large crystals growing.

419
00:27:58,527 --> 00:28:00,767
And when you get a rock
with large crystals,

420
00:28:00,767 --> 00:28:02,883
that's what we call coarse-grained.

421
00:28:05,687 --> 00:28:09,607
The large crystals in the gabbro rocks
give away their origin.

422
00:28:09,607 --> 00:28:12,927
They tell geologists that the Cuillin hills
are the remains

423
00:28:12,927 --> 00:28:16,487
of an enormous magma chamber
deep below the volcano,

424
00:28:16,487 --> 00:28:20,799
where lava was stored
before being erupted on to the surface.

425
00:28:22,727 --> 00:28:25,367
But how much lava was there?

426
00:28:25,367 --> 00:28:27,407
We may be looking now

427
00:28:27,407 --> 00:28:29,287
at a beautiful green valley,

428
00:28:29,287 --> 00:28:32,887
but actually all these hills around here
are made up of rocks

429
00:28:32,887 --> 00:28:36,167
that were formed in a series
of massive volcanic eruptions,

430
00:28:36,167 --> 00:28:38,287
about 60 million years ago.

431
00:28:38,287 --> 00:28:42,527
And at that time, there were volcanoes
erupting all over Scotland.

432
00:28:42,527 --> 00:28:45,883
Here we are on Skye
and it's just one of those volcanoes.

433
00:28:49,007 --> 00:28:53,927
It's now known that an
incredible 500 cubic miles of lava

434
00:28:53,927 --> 00:28:56,999
was erupted on Skye alone.

435
00:28:58,487 --> 00:29:04,005
That's enough to cover the whole of
Texas with a layer of lava ten feet thick.

436
00:29:07,487 --> 00:29:09,767
But this was just the tip of the iceberg.

437
00:29:09,767 --> 00:29:14,447
The rocks themselves reveal that
volcanoes erupted all over Scotland

438
00:29:14,447 --> 00:29:15,960
on a massive scale.

439
00:29:17,007 --> 00:29:18,807
The evidence is here.

440
00:29:18,807 --> 00:29:21,887
Huge, regular columns in the lava flows,

441
00:29:21,887 --> 00:29:24,967
looking like they've been
carved out of the rock.

442
00:29:24,967 --> 00:29:30,405
In reality, these amazing formations are
made by gentle cooling of thick lavas.

443
00:29:31,487 --> 00:29:35,527
Exactly the same type of columns
are found in outcrops

444
00:29:35,527 --> 00:29:40,807
of basalt lava 80 miles away
off the west coast of Scotland,

445
00:29:40,807 --> 00:29:47,687
and as far away as the coast of Ireland,
150 miles from Skye.

446
00:29:47,687 --> 00:29:51,487
These lavas have all been
dated at about 60 million years old,

447
00:29:51,487 --> 00:29:55,487
and they were also part of the
same series of massive eruptions

448
00:29:55,487 --> 00:29:58,447
which spread out for hundreds of miles
in all directions.

449
00:29:58,447 --> 00:30:01,847
But what was the cause
of the eruptions?

450
00:30:01,847 --> 00:30:04,207
Dr Goodenough has found another clue

451
00:30:04,207 --> 00:30:06,767
which points to the origins
of these lavas,

452
00:30:06,767 --> 00:30:10,287
and their role in the creation
of Loch Ness.

453
00:30:10,287 --> 00:30:13,607
This is the ropey top
to a lava flow.

454
00:30:13,607 --> 00:30:15,767
In Hawaii they call it pahoehoe.

455
00:30:15,767 --> 00:30:21,407
And what happens is that the lava gets
a thin skin on its surface as it cools,

456
00:30:21,407 --> 00:30:23,807
but it's still flowing underneath that skin.

457
00:30:23,807 --> 00:30:26,887
And the thin skin wrinkles
and gets pushed forward,

458
00:30:26,887 --> 00:30:29,487
giving this ropey texture
that we can see here.

459
00:30:29,487 --> 00:30:33,047
But it's really quite rare to see them
like this in these old lava flows.

460
00:30:33,047 --> 00:30:35,927
But it tells us a lot
about the type of magma

461
00:30:35,927 --> 00:30:38,236
that was erupting from that volcano.

462
00:30:40,687 --> 00:30:45,007
Geologists know that this kind of magma
comes from deep within the Earth.

463
00:30:45,007 --> 00:30:47,287
It usually erupts on the surface

464
00:30:47,287 --> 00:30:50,687
when tectonic forces split
the Earth's crust apart.

465
00:30:50,687 --> 00:30:54,447
Is that what happened here,
60 million years ago?

466
00:30:54,447 --> 00:30:58,287
GOODENOUGH: At that time, Scotland
was still joined to North America,

467
00:30:58,287 --> 00:31:01,767
but the two continents
were being stretched and thinned,

468
00:31:01,767 --> 00:31:03,647
due to tectonic forces.

469
00:31:03,647 --> 00:31:08,127
And that allowed molten rock,
or magma, from deep within the Earth

470
00:31:08,127 --> 00:31:11,167
to well up and to be erupted
from those volcanoes,

471
00:31:11,167 --> 00:31:15,527
and eventually that volcanic activity
led to the development of a new ocean

472
00:31:15,527 --> 00:31:19,202
between Scotland and North America,
the Atlantic Ocean.

473
00:31:20,727 --> 00:31:23,167
So the lavas are the trail of evidence

474
00:31:23,167 --> 00:31:25,887
which show that the opening up
of the Atlantic Ocean

475
00:31:25,887 --> 00:31:30,165
began with volcanic eruptions
all over Scotland.

476
00:31:31,207 --> 00:31:35,367
As magma erupted under the ocean,
the sea floor spread out,

477
00:31:35,367 --> 00:31:39,807
slowly pushing Scotland
and America apart.

478
00:31:39,807 --> 00:31:42,687
The birth of the Atlantic Ocean
had a direct effect

479
00:31:42,687 --> 00:31:44,647
on the making of Loch Ness.

480
00:31:44,647 --> 00:31:49,007
As the ocean grew, the huge
forces involved reawakened

481
00:31:49,007 --> 00:31:53,007
the 400-million-year-old
Great Glen Fault.

482
00:31:53,007 --> 00:31:55,167
So faults
like the Great Glen,

483
00:31:55,167 --> 00:31:57,727
these are zones of weakness
in Earth's crust

484
00:31:57,727 --> 00:32:01,247
and they're like scars or wounds,
they can reopen.

485
00:32:01,247 --> 00:32:03,767
And in the case of the Great Glen,

486
00:32:03,767 --> 00:32:07,167
it was reactivated
when the Atlantic began opening

487
00:32:07,167 --> 00:32:09,007
50 to 60 million years ago.

488
00:32:09,007 --> 00:32:14,087
And this is why you see this feature
now present in today's landscape,

489
00:32:14,087 --> 00:32:17,087
even though the fault itself
is 400 million years old.

490
00:32:17,087 --> 00:32:20,087
The massive geological
movements shattered

491
00:32:20,087 --> 00:32:22,407
and weakened the rocks along the fault.

492
00:32:22,407 --> 00:32:24,687
Along this line of weakness,

493
00:32:24,687 --> 00:32:27,567
a river started cutting down
through the shattered rocks,

494
00:32:27,567 --> 00:32:29,523
slowly carving out a valley.

495
00:32:31,407 --> 00:32:33,887
For the next 55 million years,

496
00:32:33,887 --> 00:32:37,607
the landscape of Scotland
weathered and eroded.

497
00:32:37,607 --> 00:32:39,727
The outlines of the mountains softened,

498
00:32:39,727 --> 00:32:43,687
and the coastline began
to take on its present shape.

499
00:32:43,687 --> 00:32:49,603
Loch Ness became a long river valley,
following the line of the Great Glen Fault.

500
00:32:51,487 --> 00:32:54,927
The investigation is close to
uncovering the final stages

501
00:32:54,927 --> 00:32:57,727
in the story of how
Loch Ness was made.

502
00:32:57,727 --> 00:33:03,287
Huge lava flows on the Isle of Skye
reveal that massive volcanic eruptions

503
00:33:03,287 --> 00:33:06,407
60 million years ago
were the start of the separation

504
00:33:06,407 --> 00:33:09,367
of Scotland and America.

505
00:33:09,367 --> 00:33:13,527
The sharp outline of the
400-million-year-old Great Glen Fault

506
00:33:13,527 --> 00:33:18,920
shows that the fault was reawakened as
Scotland and America were torn apart.

507
00:33:20,207 --> 00:33:24,927
But there was one final
land-changing event to come.

508
00:33:24,927 --> 00:33:26,847
Nature wasn't finished with Loch Ness,

509
00:33:26,847 --> 00:33:31,523
and it was this event
that created the lake we see today.

510
00:33:34,967 --> 00:33:39,207
Tracing a violent history
that lasted for three billion years,

511
00:33:39,207 --> 00:33:41,647
the investigation into how Loch Ness
was made

512
00:33:41,647 --> 00:33:47,358
now moves forward to the recent past,
only 10,000 years ago.

513
00:33:48,447 --> 00:33:51,687
The final link in the chain
of evidence is to discover

514
00:33:51,687 --> 00:33:55,127
how the wide, deep waters
of Loch Ness were finally made,

515
00:33:55,127 --> 00:33:58,247
and whether a descendant
of the dinosaurs

516
00:33:58,247 --> 00:33:59,887
could possibly have survived there

517
00:33:59,887 --> 00:34:03,243
to create the myth
of the Loch Ness monster.

518
00:34:04,487 --> 00:34:07,647
A vital clue was uncovered
in the 19th century

519
00:34:07,647 --> 00:34:11,567
by one of the greatest scientific minds
the world has ever known,

520
00:34:11,567 --> 00:34:14,007
Charles Darwin.

521
00:34:14,007 --> 00:34:16,887
In 1838, Darwin came to Scotland

522
00:34:16,887 --> 00:34:19,327
to investigate a mystery
in the remote valley

523
00:34:19,327 --> 00:34:23,320
of Glen Roy, about 20 miles
from Loch Ness.

524
00:34:25,167 --> 00:34:26,767
For hundreds of years,

525
00:34:26,767 --> 00:34:30,327
people had been baffled
by three extraordinary parallel lines

526
00:34:30,327 --> 00:34:33,567
which run round both sides
of the valley -

527
00:34:33,567 --> 00:34:40,127
strange horizontal cuts in the hillside,
in some places more than 30 feet wide.

528
00:34:40,127 --> 00:34:43,527
These Parallel Roads,
as they are called,

529
00:34:43,527 --> 00:34:46,407
run exactly level for more than 20 miles.

530
00:34:46,407 --> 00:34:48,477
What could have made them?

531
00:34:50,207 --> 00:34:52,367
Dr Pete Nienow is following
in Darwin's footsteps

532
00:34:52,367 --> 00:34:57,566
to the Glen Roy Parallel Roads
and the story they reveal.

533
00:34:58,687 --> 00:35:01,047
Their creation was a mystery
for a very long time

534
00:35:01,047 --> 00:35:03,407
and initially people, you know,
just thought they were,

535
00:35:03,407 --> 00:35:06,847
you know, perhaps created by giants,
a thing of myth or legend.

536
00:35:06,847 --> 00:35:10,527
And then in the... in the 19th century,
a number of scientists came here,

537
00:35:10,527 --> 00:35:13,287
including Charles Darwin,
and when he saw them,

538
00:35:13,287 --> 00:35:15,327
he thought they were exactly the same

539
00:35:15,327 --> 00:35:17,567
as features he'd seen
in South America,

540
00:35:17,567 --> 00:35:21,367
where earthquakes had uplifted
old marine shorelines

541
00:35:21,367 --> 00:35:23,562
and left them abandoned
higher up from the sea.

542
00:35:25,447 --> 00:35:26,967
Darwin was so convinced

543
00:35:26,967 --> 00:35:29,767
the Parallel Roads were
the remains of old seashores

544
00:35:29,767 --> 00:35:32,087
that he published a paper
with his results,

545
00:35:32,087 --> 00:35:34,157
and the world of science believed him.

546
00:35:36,047 --> 00:35:39,567
But for once, Darwin was wrong.

547
00:35:39,567 --> 00:35:43,127
In 1840, two years after Darwin's visit,

548
00:35:43,127 --> 00:35:46,915
a Swiss scientist named Louis Agassiz
came to Glen Roy.

549
00:35:48,647 --> 00:35:51,047
Agassiz had spent a lifetime
studying glaciers

550
00:35:51,047 --> 00:35:55,643
and the effects of glaciation
on the landscape of the Swiss Alps.

551
00:36:00,007 --> 00:36:02,167
When he examined the parallel roads,

552
00:36:02,167 --> 00:36:05,607
Agassiz realised that
they were ancient shorelines,

553
00:36:05,607 --> 00:36:08,447
but that the valley had been
filled not by the sea,

554
00:36:08,447 --> 00:36:11,439
but by a freshwater lake.

555
00:36:13,647 --> 00:36:15,967
From his knowledge of glaciers
in the Alps,

556
00:36:15,967 --> 00:36:18,647
Agassiz was able to show
that a freshwater lake

557
00:36:18,647 --> 00:36:20,239
had once filled the valley.

558
00:36:21,887 --> 00:36:26,967
The lake was kept full by a huge glacier
which blocked the end of the valley.

559
00:36:26,967 --> 00:36:30,247
As the glacier melted and froze again
three times,

560
00:36:30,247 --> 00:36:34,127
the water in the valley emptied
and filled up to a different level,

561
00:36:34,127 --> 00:36:37,164
carving out the three relic beaches.

562
00:36:38,207 --> 00:36:40,647
Initially, Agassiz wasn't believed,
'cause people believed Darwin,

563
00:36:40,647 --> 00:36:43,967
and then over time it became clear
that Agassiz was correct

564
00:36:43,967 --> 00:36:47,167
and Darwin claimed, you know,
it was one of his great embarrassments

565
00:36:47,167 --> 00:36:49,527
that he'd got something
so terribly wrong,

566
00:36:49,527 --> 00:36:51,287
which sort of shows that, you know,

567
00:36:51,287 --> 00:36:53,164
even great scientists
can make mistakes.

568
00:36:54,367 --> 00:36:57,327
The evidence at Glen Roy convinced
Agassiz that many features

569
00:36:57,327 --> 00:37:00,967
in the Scottish landscape
must have been made by glaciers.

570
00:37:00,967 --> 00:37:04,887
And that led him to the startling
conclusion at the time,

571
00:37:04,887 --> 00:37:08,277
that the whole of Scotland
had once been covered by ice.

572
00:37:10,167 --> 00:37:12,047
The moment
you make that leap

573
00:37:12,047 --> 00:37:14,487
that what you've got here
was created by glaciers,

574
00:37:14,487 --> 00:37:16,367
you've instantly got to make the leap
to the fact

575
00:37:16,367 --> 00:37:18,847
that we must have had
a very cold climate here in the past,

576
00:37:18,847 --> 00:37:22,927
cold enough for... for ice sheets
and glaciers to... to build up.

577
00:37:22,927 --> 00:37:25,207
This site is... is of... of world importance

578
00:37:25,207 --> 00:37:28,167
in terms of the understanding
of glaciations

579
00:37:28,167 --> 00:37:30,247
and the... you know,
the... the fact that, in the past,

580
00:37:30,247 --> 00:37:34,206
ice covered a much larger proportion
of the planet than it currently covers.

581
00:37:35,407 --> 00:37:40,407
This extraordinary investigation led
eventually to the idea of the Ice Age,

582
00:37:40,407 --> 00:37:44,407
periods in the geological past when
much of the northern hemisphere

583
00:37:44,407 --> 00:37:47,638
was covered in glaciers and ice sheets.

584
00:37:49,127 --> 00:37:53,927
Since Agassiz's discoveries, scientists
have been investigating the role of ice

585
00:37:53,927 --> 00:37:55,687
in making Loch Ness.

586
00:37:55,687 --> 00:37:59,207
About two and a half million years ago,
the global climate started to cool

587
00:37:59,207 --> 00:38:02,487
and since then we've had a series
of repeated glaciations,

588
00:38:02,487 --> 00:38:05,285
roughly about once every 100,000 years.

589
00:38:06,887 --> 00:38:10,367
Each time the ice advanced,
temperatures plummeted.

590
00:38:10,367 --> 00:38:14,327
Average winter temperatures were
at least 30 degrees colder than today.

591
00:38:14,327 --> 00:38:18,320
As the ice built up, it reached
extraordinary thicknesses.

592
00:38:19,527 --> 00:38:21,567
The ice sheet over
the centre of Scotland

593
00:38:21,567 --> 00:38:23,767
would have been three
or four thousand feet thick.

594
00:38:23,767 --> 00:38:25,447
And here in Loch Ness,

595
00:38:25,447 --> 00:38:28,807
it would have certainly been
a couple of thousand feet thick.

596
00:38:28,807 --> 00:38:31,487
You might have seen a few
of the highest mountains

597
00:38:31,487 --> 00:38:33,287
just peeking out the top of the ice sheet,

598
00:38:33,287 --> 00:38:35,367
but in the main,
the whole of the landscape

599
00:38:35,367 --> 00:38:37,801
would have just been
blanketed by... by ice.

600
00:38:39,647 --> 00:38:45,167
But what effect did this vast weight of ice
have on the creation of Loch Ness?

601
00:38:45,167 --> 00:38:48,807
The loch itself is difficult to investigate,
because it's full of water.

602
00:38:48,807 --> 00:38:52,567
But there's another location
where the evidence is clear.

603
00:38:52,567 --> 00:38:57,322
Just 20 miles from Loch Ness
is the forbidding valley of Glencoe.

604
00:38:59,487 --> 00:39:01,927
Glencoe is a legendary place
in Scottish history,

605
00:39:01,927 --> 00:39:06,767
as it was here that an infamous
massacre took place in 1692,

606
00:39:06,767 --> 00:39:09,727
when the MacDonald clan
were murdered in their beds

607
00:39:09,727 --> 00:39:11,365
by the Campbells.

608
00:39:13,327 --> 00:39:17,847
The shape of this valley sheds light
on the way Loch Ness was made.

609
00:39:17,847 --> 00:39:20,967
If you could actually drain
the water out of Loch Ness,

610
00:39:20,967 --> 00:39:25,407
what you'd actually end up with
is a valley with this sort of shape.

611
00:39:25,407 --> 00:39:27,007
And looking down Glencoe

612
00:39:27,007 --> 00:39:30,767
you can see it's a very, very steep-sided,
flat-bottomed valley

613
00:39:30,767 --> 00:39:33,887
and it's basically been created
by glaciers

614
00:39:33,887 --> 00:39:36,007
repeatedly flowing down the valley,

615
00:39:36,007 --> 00:39:39,887
eroding it and basically gouging out
what was originally a V-shaped valley

616
00:39:39,887 --> 00:39:42,196
and turning it into
an over-deepened U-shaped valley.

617
00:39:44,047 --> 00:39:47,087
Glaciers are extremely efficient
at eroding the landscape.

618
00:39:47,087 --> 00:39:49,367
They pick up vast amounts
of rock debris,

619
00:39:49,367 --> 00:39:52,567
which is carried along at the base
of the glacier.

620
00:39:52,567 --> 00:39:55,967
With the weight of millions
of tons of ice on top of it,

621
00:39:55,967 --> 00:39:59,727
this rock debris grinds away the bedrock
like sandpaper,

622
00:39:59,727 --> 00:40:03,959
scouring and deepening the valleys
to a characteristic U shape.

623
00:40:06,167 --> 00:40:08,047
Across Scotland,
there are hundreds of valleys

624
00:40:08,047 --> 00:40:09,807
with this distinctive U shape,

625
00:40:09,807 --> 00:40:12,887
bearing witness
to the huge number of glaciers

626
00:40:12,887 --> 00:40:15,924
which once covered this whole region.

627
00:40:18,247 --> 00:40:20,607
At Loch Ness,
underwater mapping has revealed

628
00:40:20,607 --> 00:40:23,527
that the loch
has this signature U shape.

629
00:40:23,527 --> 00:40:27,487
It's flat-bottomed, with very steep sides.

630
00:40:27,487 --> 00:40:30,167
In some places only 50 feet
from the shoreline,

631
00:40:30,167 --> 00:40:32,247
the water is over 500 feet deep,

632
00:40:32,247 --> 00:40:37,321
further proof that Loch Ness was made
by a glacier.

633
00:40:39,127 --> 00:40:41,647
There was already a long river valley

634
00:40:41,647 --> 00:40:43,647
which had formed
along the line of weakness

635
00:40:43,647 --> 00:40:47,647
created by the shattered rocks
along the Great Glen Fault.

636
00:40:47,647 --> 00:40:50,567
Then, during the last Ice Age,

637
00:40:50,567 --> 00:40:56,127
a giant glacier flowed down the valley,
slowly carving out Loch Ness.

638
00:40:56,127 --> 00:40:59,567
As ice flows down it, it scours it out,
deepens it

639
00:40:59,567 --> 00:41:01,847
and over a... over
a series of glaciations

640
00:41:01,847 --> 00:41:06,125
it deepens it to the extent that it's now,
you know, a loch 750 feet deep.

641
00:41:08,087 --> 00:41:11,887
The investigation is now faced
with two final questions.

642
00:41:11,887 --> 00:41:15,167
How did Loch Ness
fill up with freshwater?

643
00:41:15,167 --> 00:41:16,680
And what keeps it full?

644
00:41:17,887 --> 00:41:22,367
Loose rock and boulders found
on a huge ridge 250 feet high

645
00:41:22,367 --> 00:41:25,803
at the head of the loch
could provide the answer.

646
00:41:27,527 --> 00:41:31,367
The immediately obvious thing
about these large rocks

647
00:41:31,367 --> 00:41:33,847
is that they're extremely smooth
and well-rounded

648
00:41:33,847 --> 00:41:37,087
and that indicates that they've
been transported by... by water.

649
00:41:37,087 --> 00:41:40,607
They're also very large, this is very
heavy, so you need a lot of energy,

650
00:41:40,607 --> 00:41:43,647
so that tells you that you've got
a lot of meltwater that's carried it

651
00:41:43,647 --> 00:41:46,639
and then subsequently dumped it
where we are now.

652
00:41:48,487 --> 00:41:52,007
This evidence, combined
with discoveries about climate change,

653
00:41:52,007 --> 00:41:54,167
shows what happened here.

654
00:41:54,167 --> 00:41:58,847
About 10,000 years ago,
global temperatures rose rapidly,

655
00:41:58,847 --> 00:42:02,567
the ice began to melt,
and the glaciers retreated.

656
00:42:02,567 --> 00:42:07,087
Glaciers down there would
have been eroding Loch Ness,

657
00:42:07,087 --> 00:42:08,887
bringing up large amounts
of sediment

658
00:42:08,887 --> 00:42:12,207
and that sediment is then
being transported in this direction

659
00:42:12,207 --> 00:42:15,882
by the... by the flowing ice
and also by flowing meltwater.

660
00:42:17,567 --> 00:42:22,247
As the ice melted, a huge river
formed under the Loch Ness glacier,

661
00:42:22,247 --> 00:42:25,247
carrying with it vast amounts
of rock debris.

662
00:42:25,247 --> 00:42:29,407
And then what we've got here, what
we're standing on is in effect the zone

663
00:42:29,407 --> 00:42:31,875
where the glacier is now
dumping that sediment.

664
00:42:33,247 --> 00:42:36,367
Millions of tons of rocks
created an enormous plug

665
00:42:36,367 --> 00:42:40,647
which dammed the river
and stopped the water from escaping.

666
00:42:40,647 --> 00:42:44,167
As the ice melted,
the valley filled up,

667
00:42:44,167 --> 00:42:47,842
finally making the lake
we know as Loch Ness.

668
00:42:49,167 --> 00:42:52,167
Loch Ness is only 10,000 years old,

669
00:42:52,167 --> 00:42:56,487
but the investigation into its history
has revealed an amazing story.

670
00:42:56,487 --> 00:42:59,887
Old red sandstone rocks
show that Scotland and the US

671
00:42:59,887 --> 00:43:01,767
were once joined together.

672
00:43:01,767 --> 00:43:05,687
The shape of Loch Ness
is controlled by the Great Glen Fault,

673
00:43:05,687 --> 00:43:09,247
formed when Scotland and America
crashed into England

674
00:43:09,247 --> 00:43:12,367
more than 400 million years ago.

675
00:43:12,367 --> 00:43:16,567
Fossilised dinosaur footprints
place Loch Ness near the equator

676
00:43:16,567 --> 00:43:19,127
during the Jurassic period.

677
00:43:19,127 --> 00:43:23,567
Lava flows reveal that massive
volcanic eruptions 60 million years ago

678
00:43:23,567 --> 00:43:27,607
began the separation
of Scotland and America.

679
00:43:27,607 --> 00:43:29,327
And the profile of Loch Ness

680
00:43:29,327 --> 00:43:33,487
proves that it was carved out
by glaciers 10,000 years ago,

681
00:43:33,487 --> 00:43:37,727
finally creating the Loch Ness
we know today.

682
00:43:37,727 --> 00:43:41,327
But what of the Loch Ness monster?

683
00:43:41,327 --> 00:43:44,847
The iconic image
is now known to be a fake.

684
00:43:44,847 --> 00:43:47,327
But is there any way
that the mythical beast

685
00:43:47,327 --> 00:43:50,407
could be a descendant of the dinosaurs?

686
00:43:50,407 --> 00:43:53,287
We have two
geological facts

687
00:43:53,287 --> 00:43:55,087
that tell us that Loch Ness

688
00:43:55,087 --> 00:43:57,527
could not be inhabited by a dinosaur -

689
00:43:57,527 --> 00:44:01,607
one is the dinosaurs died a long, long,
long time ago,

690
00:44:01,607 --> 00:44:05,527
and the loch itself, geologically,
is very young.

691
00:44:05,527 --> 00:44:08,567
Dinosaurs went extinct
65 million years ago.

692
00:44:08,567 --> 00:44:13,287
So, 65 million years to 10,000 years,

693
00:44:13,287 --> 00:44:17,767
it's a long time distance and there is
no chance at all that you would have,

694
00:44:17,767 --> 00:44:20,807
preserved in this loch,
an ancient monster

695
00:44:20,807 --> 00:44:22,847
from times millions of years ago.

696
00:44:22,847 --> 00:44:24,527
The loch's too young.

697
00:44:24,527 --> 00:44:27,041
(GROWLS)

698
00:44:28,127 --> 00:44:31,407
So the geological evidence
proves that Loch Ness

699
00:44:31,407 --> 00:44:35,127
could not be home to a dinosaur
that somehow survived there

700
00:44:35,127 --> 00:44:37,607
since the Jurassic.

701
00:44:37,607 --> 00:44:43,887
The awesome geological history of Loch
Ness has thrown up many mysteries.

702
00:44:43,887 --> 00:44:47,800
But for science, the Loch Ness monster
is not one of them.