Original subtitles

[man speaking]

[suspenseful music playing]

[narrator] A strange foundation is uncovered

on a remote Siberian Island

It would have taken a lot of time and energy

to build this enormous complex.

The crumbling walls and ruin

practically cover the entire island.

[narrator] A shocking discovery

on New Zealand's highest pea

might mean rewriting the history books.

[Amma] And when the men were found

their ropes were coiled up.

This suggests that they weren't climbing

when they died.

[narrator] Mysterious formations

on an Artic beach

lead to a grisly discovery.

It's an eerie almost alien sight.

What could have created these bizarre circles

on this forgotten island?

Something really horrific must have happened

to kill off so many people.

[narrator] These are the strangest mysteries,

trapped in the coldest places.

Lost relics,

forgotten treasures,

dark secrets,

locked in their icy tombs for ages.

But now, as ice melts around the world,

their stories will finally be exposed.

[suspenseful music playing]

[narrator] Deep in the Sengelen mountains

of Southern Siberia,

20 mi from Russia's border with Mongolia,

a small island in the cente of the frigid Lake Tere-Kho

harbors a big mystery.

At 4,000 ft above sea level,

Lake Tere-Khol is high up in the mountains.

It regularly gets down

to -50 degrees Fahrenheit in the winter,

and the ground surrounding the lake

is predominantly permafrost

[narrator] Archaeologists working

in the remote mountains

come across an unusual sigh

in the middle of the lake.

Out on a small eight and a half acre island

they see the ruined remains

of numerous large walls and buildings.

The crumbling walls and ruins

practically cover the entire island.

What is this place?

[narrator] The complex is made up

of a large rectangular external wall,

705 ft long

by 531 ft wide.

Inside, there are two main courtyards

and the remains of a large central structure.

A chain of smaller interconnected walled yards

and buildings around the perimeter.

The complex on the island is about the size

of two football fields.

I mean, that is huge.

The exterior wall or curtain wall

is also really thick,

about 40 ft at its widest

and also about 30 to 40 ft high.

All the walls and buildings are made of clay bricks,

so the site has become known as Por-Bazhyn

or the Clay House.

Based on the types of material

and construction methods used,

archaeologists believe the site must be at least

a thousand years old.

It would have taken a lot of time and energy

to build this enormous complex,

especially in such a cold and remote location.

But you can just imagine how it would have looked,

this huge walled structure standing out there

in the middle of the lake,

it would have been really stunning.

[narrator] Bizarrely, the archeologists find

very little evidence of huma presence at Por-Bazhyn.

When humans spend a prolonge period of time somewhere,

they leave behind what archaeologists call

a cultural or occupational layer of artifacts.

But at this site, they find nothing.

With no evidence to indicate who lived here,

archaeologists must now dig deeper to determine

what this massive structure was.

[Anthony] In the winter, this part of Siberia is cold

And archaeologists don't even find evidence

that they tried to heat this place.

No fires, no hearths.

There were thick walls

which could dampen some of the cold

but when temperatures are well below freezing

all winter long,

this place would be unlivable.

With no evidence of heating and no cultural layer,

it doesn't appear that anyone actually lived here.

Why would someone build

such an elaborate structure on an island

in the middle of nowhere,

only to leave it unoccupied?

[Amma] At 40 ft high,

that exterior wall was really good

for keeping people out.

And its position on the island

is similar to the classic military tradition

of building moats around forts and castles.

[Dr. Cantor] If it's not a domestic structure,

then perhaps it could have been a military site.

Who was living here around a thousand years ago

that needed to protect themselves?

[narrator] During the Middle Ages,

the Uyghurs, a nomadic Turkic speaking people,

once ruled an empire that spanned across Mongoli

and into Southern Siberia.

They were known for their formidable fighting skills

and dominated the area for centuries.

[Dr. Leonard] Today, this ar seems incredibly remote

and out of the way,

but during the Uyghur Empire

there were a number of trading routes

and other villages nearby.

So this site could have been

a strategic location for defense.

[Anthony] Looking at the outer walls,

researchers do find the remains

of a wooden fighting platfor

running along the eastern side.

So it's possible that this place was built

with defense in mind.

But when you look closely

at the structure and the layout,

all of the rooms and smaller courtyards

do not open into the main square.

[Dr. Leonard] If troops suddenly needed to mobilize

on short notice,

this design feature would create a bottleneck,

it would be a total disaster.

[Amma] And remember, it's surrounded by water.

So quickly, getting out of there

is gonna be a challenge.

But maybe that was the point.

The tall walls would have been good

for keeping people out,

but could maybe also be use to keep people in.

It's possible that this place

was built to be used as a prison.

Islands are used as prisons all the time.

I mean, think of Alcatraz or Rikers Island.

And a remote location on a lake would have been

a huge deterrent for prisoners hoping to escape.

[narrator] Archeologists find traces of repairs

to the plaster walls,

suggesting that the site had been kept up

and maintained for a long period of time.

Some of the interior walls were painted

with red and black stripes

and even have evidence of painted fresco.

So clearly, whoever built this place

was also invested in how it would look.

But you wouldn't go through all that trouble

of making it look nice

just to keep prisoners there.

Maybe, looking at the construction

of the building itself,

and the materials that were used

can give us a clue

as to the origin and the function.

[Dr. Leonard] Building on su a remote island

would be extremely challenging.

The walls appear to be made

by an ancient construction method

called Hang t'u,

also known as rammed earth construction

Clay rich soil is mixed with gravel or sand

and pressed into wooden form to create bricks.

[narrator] Uncovered at the site,

preserved in the cold ground

researchers find decorative tiles

with intricate patterns and dragon faces on them.

This suggests that the builders

could have been Chinese

or maybe they'd studied Chinese building methods.

Hang t'u is a traditional

Tang Dynasty style of building

and decorated roof tiles like these

were popular in China during the Middle Ages.

[Anthony] This area has been lived in

and ruled over by many different groups and culture

over the years.

So until this material is dated,

it's gonna be really hard to get an accurate assessment

of who actually built this place.

[narrator] But in 2020,

an international team of researchers announced

that they have made a discovery

that could solve the myster of Por-Bazhyn

once and for all.

[narrator] On a remote Siberian Island,

known as Por-Bazhyn,

archaeologists may have finally uncovered a clue

that will solve the centuries old mystery

of who built this place.

They have uncovered a well-preserved

wooden timber beam deep

in the site's foundations.

The walls were primarily made of clay bricks,

and wood was just a secondary construction material.

But because this beam was found

in the base layers of the wall,

it means it was placed early on during construction

But if archaeologists can date the wood,

it'll give us much more precise information

about when the structure was built,

and who built it.

[narrator] Scientists have determined

that on very rare occasions

radio carbon in the atmosphere

can inexplicably rise.

A largest jump like this occurred in the year 775.

This excess carbon is often seen

in the rings of trees that were alive

during that era.

On the wooden beam from Por-Bazhyn,

researchers were able to identify the growth ring

that was formed in 775.

From there, they simply counted the tree rings

to the bark edge to find out exactly

when it was cut.

Two more rings formed after that year,

so this tree must have been felled and used

in the summer of 777 AD.

[narrator] This date places the construction

of Por-Bazhyn to the reign of Uyghur ruler

Tengri Bogu Qaghan.

[Dr. Leonard] He was really interesting,

most of the Uyghurs at the time

practice Buddhism.

But Bogu Qaghan had converted to Manichaeism,

and he made it the official religion of his empire.

He was actively trying to convert his subjects

and may have needed a place for them to study and pray.

Could this strange Island complex

be a Manichaean monastery?

[Amma] The layout of the buildings

on the island are similar

to a walled Buddhist temple or a monastery.

There's a grand central courtyard

that's surrounded by smaller structures

where the monks live and study.

But Bogu Qaghan was killed in 779 AD,

and under the next ruler,

the official religion was changed yet again.

[Dr. Leonard] The constructi of the Por-Bazhyn site

had only started a couple of years

before Bogu Qaghan died.

So there would have been virtually no time

for it to be used as a monastery.

This could explain why there is no evidence

that the site was ever occupied.

While there isn't a definite answer

on the true purpose of the building,

researchers don't have much time

to continue studying the site.

The island itself is a plug of permafrost

and so as temperatures rise it will thaw and soften.

That means that in about 80 years,

its walls will collapse into the lake,

taking its secrets with it.

[suspenseful music playing]

[narrator] Running hundreds of miles

across New Zealand South Island

is the intimidating Southern Alps mountain range

And at over 12,000 ft above sea level,

looms the indomitable peak of Mount Cook.

As the tallest mountain in the range,

Mount Cook is the stuff of legend.

It's a magnet for climbers

willing to risk their lives to climb it.

In Maori culture,

this icy behemoth is known as Aoraki.

It's fabled to be the body of a sky god

that came to earth,

slowly turned into rock

and became the mountain itself,

creating life.

But the mountain can also take life away.

Eighty people have died trying to climb it.

[narrator] In 1999,

a pair of mountaineers are climbing down

Mount Cook's Southwestern face

when they spot something unusual,

a flash of orange

lying half buried in the snow.

They inch closer to get a better look

and poking out of the melting glacier

is a beat up climbing helmet.

[narrator] Inside the crushed helmet

was a human skull.

[Jamie] Finding a discarded or lost climbing helmet

is not common.

And the intact skull of its owner inside

is a shocking reminder of our mortality.

Uh, it would be a terrifyingly scary discovery

for any climber.

[Amma] But once the shock subsides

curiosity kicks in.

Surely, the rest of the bod

is out there somewhere on the mountain.

What happened to this person?

[narrator] Mount Cook is an intimidating peak,

but a huge draw for climbers worldwide.

In the past, legendary explorers

have used it as a training ground,

such as Edmund Hillary

before his historic ascent of Mount Everest.

What makes climbing Mount Cook an enticing climb

is that there are nearly 50 routes to the top

a tremendous variety and none of them are easy.

In fact, I'd say some are nearly impossible.

[narrator] The mountain has five sides

with six faces,

and seven main ridges leading up to the peak.

The climber's helmet and skull

were found on a Hooker Glacier

on the mountain's southwestern side.

After an extensive search of the glacier,

further skeletal remains are found buried in the snow

The investigators also uncover

climbing apparatus,

crampons, ropes,

and a weather-beaten wooden climbing axe.

[Jamie] Based on their materials,

the axe, the rope,

they both appear to be from the 1960s.

No one uses this kind of gear anymore.

Whoever it is,

they've been lying here for decades.

[narrator] The remains are removed from the mountai

for forensic analysis.

In the lab,

investigators make a startling discovery.

Counting the tibias, the lower leg bones,

they determine these remains didn't belong

to just one person, but two

Something awful must have happened

to this pair of climbers on that mountain,

what could it have been?

[narrator] At more than 6,500 ft high,

the treacherous Caroline Fac

is the longest and steepest face

on the mountain.

During the 1950s and '60s,

many considered it suicidal

to even attempt such a dangerous climb.

It wasn't until 1970

when climbers John Glasgow and Peter Gough

put themselves in the history books

by becoming the first to successful scale

the Caroline Face.

It's certainly possible that the two climbers

they found on the Hooker Glacier

were trying to ascend the Caroline Face.

But investigators still nee to know who they were.

[narrator] It's unlikely the pair died

where they were found.

The investigators believe they perished

higher up the mountain,

with glacial movement having forced the bodies

slowly down.

Researchers examine the climber's gear

for any identifying feature

that could determine the owner.

[Jamie] A helmet is a very personal item.

You can tell a lot about a climber from their clothing,

but especially from their helmet.

[narrator] Close inspection reveals something scratched

into the orange plastic

of the battered helmet,

a name,

"Cousins."

Who was Cousins?

Researchers scour the list of climbers

lost on that mountain,

and they come across a match

[narrator] In early November, 1963,

two young climbers,

Michael Goldsmith and John Cousins

disappeared on Mount Cook.

Their bodies were never found.

Cousins and Goldsmith were good friends.

They were university student in their early 20s,

excellent climbers.

They'd been climbing in these mountains for years

They knew them like the back of their hand

Their disappearance was a tragedy for their familie

and for the New Zealand climbing community in general.

[narrator] The investigators trace

the last known movements of the two friends.

Sometime after midnight on November 1st, 1963,

the two young men set off for the summit

without directly informing the park ranger.

The next day, park rangers found a note

from Cousins and Goldsmith

tucked under the door of the guard hut.

It read, "Going to have a look at the Caroline Face."

[Jamie] This note suggested

they intended to at least

attempt the Caroline Face.

In 1963, it was still unclimbed.

For two young experienced climbers,

a first ascent, that'd have been a big deal

And frankly, it still is today.

Climbing Mount Cook like that,

that's a real feather in your cap.

[narrator] Is it possible the two climbers

were the first to successfully scale

the Caroline Face?

A full seven years before Gough and Glasgow?

After mountain climbers find the remains

of two bodies high atop New Zealand's tallest peak,

a team of forensic researchers

are attempting to solve a decades-old cold case.

They conclude that the remains

pulled from the mountain

are of those of Goldsmith and Cousins.

But whether they were the first to climb

the Caroline Face remains a mystery.

If they had completed the climb,

why were their bodies found in the Hooker Glacier,

on the opposite side from the Caroline Face?

Along with the gear that search and rescue crews

found within the glacier,

they also found an etrier.

It's a ladder that's typically used

for ice climbing.

[Jamie] When you're climbing

you travel as light as humanly possible,

taking with you only the most essential gear.

If the men were expecting to attempt the Caroline Face,

they would have left this at base camp.

This indicates that the pai

could have climbed the Caroline Face,

but they might have perished

on the way back down the glacier.

[Amma] And when the men were found in the glacier,

their ropes were coiled up.

This suggests that they weren't climbing

when they died.

[Mike] If this had been an avalanche,

you'd expect gear to be scattered down the mountain

far away from these bodies.

So what happened to these climbers?

[Jamie] The most likely scenario

is they sought shelter when bad weather descended.

They would have been exhausted

after a grueling climb up the Caroline Face,

and likely would have tried

to wait out the bad weather

[narrator] Hoping to find a definitive answer,

the investigators continue to look for evidence.

Amongst the climbing gear recovered with the bodies,

search and rescue also retrieved

an old German-made Braun camera

with a roll of 35 mm film preserved inside.

[Jamie] If they had scaled the Caroline Face,

they might have taken a picture as proof,

or maybe they took a picture

during their last hours or moments.

The main question is can the film be salvaged

after spending nearly 40 years beneath the ice?

[narrator] Sadly, a chemical reaction

between the iron and the camera body,

and the silver bromide

in the film developing emulsion

encased the film in silver metal,

so it couldn't be developed

It's so frustrating when the evidence

just does not cooperate.

There is so much that science can do

but it, too, has its limitations.

While the film can't confir whether Cousins and Goldsmit

ascended the Caroline Face,

the families of the men were able to get closure.

They finally knew the fate of John and Michael.

Their beloved mountain had taken them,

and they died doing what they loved most.

[suspenseful music playing]

[narrator] The Svalbard Archipelago,

a cluster of islands 900 mi north

at the Arctic Circle.

The remote collection of frozen land

is midway between Norway and the North Pole.

[Jamie] Historically, the ocean around Svalbard

was obstructed by ice most of the year,

blocking boat access.

The islands themselves

are a mix of mountainous glaciers

and barren tundra.

[narrator] In 2014,

a group of Norwegian archeologists

reached the frozen shores of Amsterdam Island.

The team are exploring a spit of land

on the island's south,

hunting for evidence of habitation.

As they make their way up the beach,

the team discovers a rocky horseshoe-shaped formation

about 8 ft in diameter.

[Dr. Elliott] The formation is made

of a dark, concrete-like material.

It appears blackened or burnt, almost like asphalt.

The team had brought a state of the art drone

to conduct aerial surveys of the area.

They get into the air

and right away capture something odd.

[narrator] The photos show six more

large horseshoe formations on the beach

all around 7 or 8 ft in diameter,

some are back to back,

creating a double helix effect.

It's an eerie almost alien sight.

What could have created these bizarre circles

on this forgotten island?

[narrator] A group of Norwegian archeologists

are investigating a cluster

of strange formations on a remote arctic island.

At first glance,

they wonder if the unique shapes were formed

by powerful geologic natural forces.

It's possible they're the remnants

of an ancient rock pool,

or maybe even small meteorite craters.

But that doesn't account

for the burnt asphalt material,

that looks manmade.

If they aren't naturally formed,

they were obviously built by people for some purpose.

So what were these circles used for?

[narrator] The archeologists wonder

if the circles were building

used by an indigenous peopl

who once called these islands home.

In Northern Canada, Greenland,

and parts of Siberia, we see igloos,

dome structures made of ice

And Inuit hunting tents do leave stone rings,

so was it possible these are Inuit structures?

[Dr. Elliott] But an igloo wouldn't leave

a rocky trace like this,

and an Inuit building would be made of stone,

not this asphalt material.

So if it's not an Inuit camp,

maybe a more modern group lived here?

[narrator] Between 850 and 1100,

the Vikings expanded their territory

from Norway to Iceland,

and west to Greenland.

[Dr. Leonard] Viking buildin were typically built

in an oval shape to resemble their warships.

These formations are round, almost circular,

so it's unlikely that this was a site

of a Viking village.

[narrator] The team scours the area

inside the formations.

The burnt remains of bone,

straw-like sticks, and moldy charcoal

are spread across the whole space.

It's strange for a couple of reasons,

that's too big of an area

to be the central hearth of a house.

And this is an unusual mix of fuels.

Fatty bone marrow burns well,

and the tiny straw-like sticks

were probably broom spindles

while the moldy charcoal was likely driftwood.

They were using anything they could find as fuel.

[Dr. Elliott] This massive fire would have generated

a tremendous amount of heat

What was happening here that needed a fire

that big and that hot?

[narrator] To learn more, the researchers expand

their investigation of the site further inland.

They're astonished

when they make the grim discovery

of dozens of shallow graves

They contain the decayed remains of 101 bodies

that have wasted away to skeletons.

[Jamie] It's a ghastly site

Something really horrific must have happened to

kill off so many people in this remote community.

[Anthony] The permafrost preserved

these people's clothes. I mean,

their skeletons are still dressed

in heavy woolen coats,

shirts, trousers, hats.

It looks like they were dressed to work

in a really frigid climate.

[narrator] Adding to the mystery,

each body has been buried

in an individual coffin made of wood.

[Dr. Elliott] The wooden coffins really stand out.

This community was so desperate for firewood

they were burning broomsticks

but they saved enough wood for a 101 coffins.

It's a strange contradiction

[narrator] Several bodies are forensically examined,

allowing researchers to date them

to the early 1600s,

many show signs of scurvy,

a deadly illness caused by a lack of Vitamin C.

[Jamie] Whoever they were, this community was living

a rough life, working in the freezing cold

subsisting on a bad diet.

But did these people

build the formations on the beach

over 400 years ago?

[narrator] The researchers head back to the beaches

in the hopes of excavating more artifacts.

Close to the circles,

they discover the remains

of large rounded pieces of copper,

they're burnt and blackened in places.

And they've corroded after years of exposure

to the salty ocean and Arctic air,

but their shape is still clear.

These look like giant copper cauldrons

and they're certainly too big for a kitchen,

which means they probably had an industrial use.

So what was being cooked in these cauldrons

on the beach?

[narrator] As the archeologists

dig into the permafrost

near the horseshoe formations,

they uncover various curiously shaped knives.

[Dr. Leonard] They look lik little hockey sticks

with long handles and curved blades.

These types of knives are typically used

in abattoirs or fisheries to butcher meat.

So what was being butchered here?

[narrator] After Norwegian archaeologists

discover a mass gravesite

containing over 100 bodies

dating back to the early 1600s,

they then uncover several large blades

possibly used for butchering

They wonder if the bodies, the blades,

and the strange formations on the beach

are somehow connected.

The team scours the beaches

and stumble across their answer

half-buried in the sand.

They find these enormous bones

buried in the ground, scattered at random.

[Dr. Leonard] Some of the bones are long,

wide, and curved.

They're whale bones.

And it looks like they're from a few different species.

[narrator] A close inspectio of the bones

reveals the scrapes, scratches,

and marks that only knives or blades could make.

So could these asphalt formations on the beach

be the most obvious remains

of a 17th century whaling station?

[narrator] Starting in the early 1600s

the Dutch, British, Danish, and Norwegians

all battled for control

of a revolutionary new commodity, whale oil,

had become the most desired fuel for lamps

and a main ingredient in soa

giving way to the rise of the blubber wars.

Throughout the 1600s the British and Dutch

were obsessed with controlling the whale oil market.

They send fleets to the edges of the earth

looking undiscovered hunting grounds.

[Anthony] The nutrient-rich Atlantic and Arctic oceans

are a favorite place for whales of all kinds

to feed during the warmer seasons.

So once the sea ice receded,

the whalers gave chase.

[Jamie] In the early 17th Century,

whalers couldn't easily boi and render the fat

while at sea.

But the Svalbard Islands

are on the whales' migration route

and made for an excellent place

for the slaughtered whales to be butchered, boiled,

and turned into oil.

[narrator] The site on Amsterdam Islan

was called Smeerenburg,

Blubber Town in Dutch.

And for nearly 40 years,

it was the main whaling station

of this Svalbard Archipelago

Rumors about Blubber Town started to spread

in the 1660s.

And by the 19th century,

it was said that it was hom to 18,000 people

complete with paved streets

bakeries, bars, and brothels

[Dr. Elliott] But the realit of Blubber Town

was a far cry from the legend.

At most, this station supported around 200 whaler

during the spring and summer months

butchering and processing whales by their hundreds.

Those oddly shaped knives were likely

flensing or mincing knives

used to butcher the whales carcasses.

Then the blubber will be boiled

and melted into oil

inside those huge copper kettles.

The stench must have been awful.

The working conditions would have been

extremely harsh and dangerou

with limited shelter and food.

[narrator] The researchers believe

the dark asphalt horseshoe formations

were the foundations for blubber ovens.

They would have housed huge fires

fueled by anything the whalers could find

to heat the copper kettles in which they would render

the whale blubber into oil.

The blackened asphalt-like substance

that formed the horseshoe circles

was an incredible combinatio of sand and gravel

bound together with whale oi

and baked into a building material.

This would have been a really strong and resilient material.

Definitely capable of supporting the copper kettle

full of boiling water and blubber.

[narrator] Smeerenburg's tim

as an important whaling station

was short-lived.

By the 1660s,

the whale population around Svalbard

was hunted to near extinction.

As whalers were forced to hunt farther

from their archipelago,

it was easier to butcher the whales at se

rather than make the trip to Smeerenburg.

Blubber Town was abandoned.

And as Svalbard Archipelago' main whaling post

was left to decay in the frozen winds

and ice of the Arctic.

Over the course of 40 odd years,

hundreds of whalers worked in awful conditions

in this harsh place.

For some poor souls,

the danger, the cold, and the diet

would prove too much.

And they were buried in the permafrost

by their peers.

Ironically, raw whale blubber is loaded with vitamin C.

So if these whalers had eaten

even a little more of their catch,

they probably wouldn't have died.

At least not of scurvy.

[suspenseful music playing]

[narrator] Greenland's vast interior

is a seemingly impenetrable sheet of ice.

In 1993,

a team of American geologist

pull ice core samples from a glacier

deep in the heart of the island.

They're hoping microscopic debris

locked in the ice can reveal more

about the Earth's climate.

[Mike] Greenland's glaciers are ancient.

The layers of snow in them

store secrets from millennia

Scientists drill cores

hundreds or even thousands of feet through this ice

in order to unlock the secrets

that are stored within it.

A 500-ft sample of core

can contain a geological record

going back centuries.

They're like time traveling ice tubes.

[narrator] The ice core samp contains a layer

made of a mysterious microscopic substance

that geologists haven't seen before.

[Dr. Cantor] The scientists are trying to find

ancient greenhouse gases.

But the material in the ice core is solid

like a microscopic powder.

What is it?

[narrator] The scientists are able to date

the ice layer that contains

the unidentified particles

to between 532 and 542.

This period is already know to researchers

as a mysterious time of climate change.

[Dr. Leonard] The Earth's temperature plummeted

to its coldest in over 2,300 years.

It's known as the year of darkness.

[narrator] In 536,

people from across Europe,

the Middle East, and Asia

experienced a never-ending fog,

a cold summer, and near-permanent darkness

[Dr. Leonard] One Roman official detailed

a perpetual blue colored su

that dimmed the full moon

and resulted in a summer without heat.

It must have been terrifying

People literally thought it was the apocalypse.

[Mike] There were reports of snowcapped trees

in the middle of summer.

Without enough light or warmth,

crops failed all across Europe.

As a result, thousands of people died of starvation.

[Dr. Cantor] The cause of th so-called year of darkness

has never been truly explained.

Was the secret trapped in Greenland's ice

this whole time?

[narrator] Until now, the leading theory

was that an enormous volcanic eruption

blotted out the sun.

Does the Greenland ice core

contain traces of volcanic ash

proving once and for all that a volcano

caused the year of darkness

[Dr. Leonard] When a volcano erupts,

volcanic ash and sulfur dioxide

are spewed into the atmosphere.

Here, they reflect the sun's light and heat

back into space cooling the planet.

[Mike] The super lightweigh dust and debris

could hang in the atmospher and circulate for years.

Eventually, it can settle down out of the atmosphere

and be locked away in these ice and rock cores

for thousands of years.

[narrator] The scientists te the core samples

for volcanic debris such as bismuth and sulfur.

They find traces of sulfate but in miniscule amounts

when compare to other eruptions

that had drastic effects on the global climate.

Certainly, not enough to block

the sun out for months.

[Mike] But this substance that's locked

in this single layer of an ice core

is still unidentified.

So if this year of darkness 536

wasn't caused by a volcanic ash cloud,

what else could it be?

[narrator] As researchers continue to investigate

a strange anomaly within an ice core sample

pulled from the center of Greenland's ice sheet,

they're able to determine

it is related to what is known

as the year of darkness.

But if the strange substanc isn't volcanic ash,

what could it be?

Another theory is a big impact from a meteorite

threw up enough dust to block the sun.

When huge meteors smash into the Earth,

the explosive impacts can force

a massive amount of debris into the sky

which blocks the sun and cools the planet.

[narrator] The geologists analyze the ice core sample

looking for evidence of extraterrestrial material

[Dr. Cantor] By comparing the substance in the ice cor

to known meteorite fragment on Earth,

they can tell if the sample is meteoric.

[narrator] But the unknown substance

is determined to be from Earth, not space.

The researchers are stumped

[Mike] The two most logical causes

of this debris in the atmosphere

that may have caused the year of darkness,

just aren't possible.

So what can this strange substance

in the ice core tell them?

[narrator] The scientists study the chemistry

of the ice core

and make a surprising discovery.

The mysterious substance

is a calcium-laden sediment

containing microscopic marine fossils.

[Dr. Cantor] The place in Greenland

this sample was pulled from

is hundreds of miles inland

So what are ocean-dwelling life forms doing there?

[Mike] But here is where it gets even stranger.

The scientists found 91 species,

all from warm tropical water

thousands of miles to the south.

It's baffling.

It's the largest deposit of microfossils

from temperate or tropical climates

ever found in an ice core.

Tropical marine fossils

way up in glacial Greenland?

It doesn't make any sense.

How did they get there?

[narrator] The researchers return

to a version of their original theory,

a volcanic eruption.

But this time, they wonder,

did the volcano under the ocean

cause the year of darkness?

[Dr. Leonard] Volcanoes are notoriously violent,

causing explosions, tsunamis and earthquakes.

The 1883 eruption of Krakatoa

is believed to have spewed 11 cubic mi of ash

and debris into the atmosphere.

That's almost 20 million Olympic size swimming pools

filled with ash.

[Dr. Cantor] The sun was blocked for three days

for hundreds of miles around Krakatoa.

And volcanic ash fell nearly 4,000 mi away.

The explosion was 10,000 times more powerful

than the atomic bomb dropped on Hiroshima.

And that volcanic energy doesn't just go away

if the eruption is underwater.

[narrator] Based on the microscopic fossils

in the ice core,

the geologists determine

that 1,500 years ago,

an underwater volcano located near the equator

could have erupted with an enormous force.

[Mike] In an underwater eruption,

clouds of ash aren't exploding

straight into the air.

Instead, the volcanic heat vaporizes the seawater.

[Dr. Cantor] Jets of steam would shoot

into the stratosphere and carry with them

those calcium-rich sediment

and microscopic sea creatures.

After floating around the Earth for a while,

they'd scatter across the planet,

including into the Arctic.

But how can the sea creature found in a Greenland glacie

prove an underwater volcano

caused the year of darkness in 536?

[narrator] Further analysis shows the calcium deposits

in fossils from the ice cor

are pale or white in color.

Researchers believe that microscopic creatures

were likely displaced from the ocean

into the atmosphere.

Just like volcanic ash,

a sustained cloud of vaporized seawater

rich in pale marine debris

would reflect the sun's light and heat

extremely efficiently.

It's also possible that this wasn't

just one underwater volcanic eruption,

but several all occurring in the same timeframe

creating one prolonged dark cold period.

So it seems like microscopic organisms

locked way up in the ice in Greenland

had a profound impact on climate

about 1,500 years ago.

The brutal twist to the stor

is that once the year of darkness

started to wane,

the light wasn't at the end of the tunnel.

So many rats died of starvation that year

that they're fleas found new homes on humans.

As a result, the Justinian Plague

was unleashed across Europe and rest of the world

killing tens of millions of people.

[Mike] And so ultimately, one dark period

led straight into the next.