All language subtitles for Secrets.of.the.Underground.S01E03.America s.Buried.Massacre.1080p.AMZN.WEB-DL.DD+2.0.H.264-playWEB_track3_[eng]

DEEP IN THE PENNSYLVANIA WOODS

LIES A DARK SECRET
FROM AMERICA'S INDUSTRIAL PAST.

I THINK WE FOUND
A MASS GRAVE SITE.

IS THIS WHERE DOZENS
OF MISSING LABORERS

WERE SECRETLY BURIED?

AND WERE THEIR DEATHS ACCIDENTAL
OR FOUL PLAY?

I'LL USE ADVANCED IMAGING
TECHNOLOGY TO INVESTIGATE.

THERE IT IS.

AND IN SOUTHWESTERN VIRGINIA,

THE FILMING LOCATION
OF THE ICONIC MOVIE

"DIRTY DANCING"
IS STEEPED IN MYSTERY.

OH, MY GOSH.
LOOK AT THAT.

WHAT CAUSED A 47-ACRE MOUNTAIN
LAKE TO SUDDENLY DISAPPEAR?

WE WERE DEVASTATED.
WE DIDN'T KNOW WHAT TO DO.

I'LL USE A NEW SEISMIC TEST
TO FIND OUT.

WHOA!

HIDDEN JUST BELOW
THE EARTH'S SURFACE,

THERE ARE COUNTLESS
UNSOLVED MYSTERIES.

AND, TODAY, WE FINALLY HAVE
THE TOOLS TO UNLOCK THEM.

LOOK AT THAT!WHOA.

I THINK THIS IS IT.

I'M ROB NELSON,

A SCIENTIST USING
STATE-OF-THE-ART TECHNOLOGY

TO PEEL THE LID OFF
OUR PLANET'S HIDDEN DEPTHS.

THE MOMENT OF TRUTH
RIGHT HERE.

HOLY MOLY!

THESE ARE THE SECRETS
OF THE UNDERGROUND.

Captions by VITAC--
www.vitac.com

CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS

IN CHESTER COUNTY,
PENNSYLVANIA,

20 MILES WEST
OF PHILADELPHIA

LIES A STRETCH OF FOREST
THAT IS SAID TO HARBOR

A DARK SECRET OF AMERICA'S
INDUSTRIAL PAST.

ACCORDING TO LOCALS, THIS AREA
IS THE SITE OF A MASS GRAVE,

THE FINAL RESTING PLACE
OF DOZENS OF IRISH IMMIGRANTS

WHO MYSTERIOUSLY PERISHED
IN THE 1830s

AND WHOSE DEATHS
WERE SUSPICIOUSLY COVERED UP

BY AUTHORITIES.

WERE THEY INNOCENT VICTIMS
OF DISEASE,

OR IS THERE A DARKER SIDE
TO THE STORY?

I'M HEADING TO SOUTHEASTERN
PENNSYLVANIA TO INVESTIGATE.

WITH THE LATEST HIGH-TECH
IMAGING TOOLS,

WE CAN NOW SEE THROUGH THE SOIL

LIKE NEVER BEFORE
AND, HOPEFULLY,

LOCATE THE OTHER BODIES.

TODAY, THE ONLY REMEMBRANCE
OF THE VICTIMS HERE

IS A MEMORIAL STONE WALL

THAT WAS ERECTED BY
A LATER GENERATION OF WORKERS

WHO HEARD ABOUT THEIR DEATHS.

THIS IS WHERE I'M MEETING LOCAL
HISTORY PROFESSOR BILL WATSON

TO FIND OUT MORE ABOUT
THE WORKERS WHO DIED.

SO THESE STORIES
GO BACK A LONG TIME.

WHAT EVIDENCE DO WE HAVE
OF A MASS GRAVE SITE?

WELL, FOR YEARS,
IT WAS JUST FOLKLORE,

NOT KNOWING WHETHER THERE
WAS ANY SUBSTANCE TO THE LEGEND.

AS A LOCAL IRISHMAN, BILL WAS
ALWAYS INTERESTED IN THIS STORY.

BUT IN 2002, HIS FASCINATION
TOOK A VERY PERSONAL TURN

WHEN HE AND HIS BROTHER
CAME ACROSS A STASH

OF LONG-LOST DOCUMENTS.

THIS IS
THE PENNSYLVANIA RAILROAD FILE

ON THE STORY
OF THE MASS GRAVE.

- CAN I SEE THIS?
- YES. ABSOLUTELY.

MY GRANDFATHER WORKED
FOR THE MAN WHO ASSEMBLED THIS.

THE PAPERS TELL
OF THE CONSTRUCTION

OF ONE THE COUNTRY'S OLDEST
COMMERCIAL RAILROADS,

THE 82-MILE PHILADELPHIA
AND COLUMBIA LINE.

SO THIS WHOLE THING
GOES BACK TO AN INCIDENT

THAT HAPPENED WHEN
THE RAILROAD WAS BUILT?

AND WHAT WE KNOW HERE
IS THAT A TOTAL OF 57

IRISH RAILROAD WORKERS
WERE INVOLVED AT THE TIME

IN THE BIGGEST
INDUSTRIAL ENDEAVOR

IN NORTH AMERICA,
ACTUALLY--

THE PHILADELPHIA
AND COLUMBIA RAILROAD.

AND WE'RE AT THE SITE
OF THE MOST DIFFICULT MILE

IN THAT ENTIRE SYSTEM.

IN 1832,
A CONTRACTOR NAMED PHILIP DUFFY

SET OUT TO CONSTRUCT
MILE 59 OF THE LINE.

THE AREA'S HILLY TERRAIN

MADE IT ONE OF THE RAILROAD'S
TOUGHEST STRETCHES.

TO BUILD WHAT CAME TO BE
KNOWN AS DUFFY'S CUT,

HE HIRED DOZENS OF LABORERS
RIGHT OFF THE DOCKS.

THEY WERE AMONG THE TENS
OF THOUSANDS OF IRISH IMMIGRANTS

WHO ARRIVED THAT YEAR,

DESPERATE TO ESCAPE
THE DESTITUTE CONDITIONS

IN THEIR NATIVE LAND.

BUT WITHIN WEEKS
OF REACHING THEIR NEW HOME,

IT SAID THAT THE LABORERS
ALL DIED

DURING A CHOLERA OUTBREAK
THAT SWEPT THROUGH THEIR CAMP.

LEGEND HAS IT THEIR BODIES
WERE THEN DUMPED

INTO A MASS GRAVE NEAR MILE 59.

YET, STRANGELY, EVEN THOUGH

THE CONFIDENTIAL COMPANY FILES

REVEAL THAT 57 WORKERS
AT DUFFY'S CUT DIED,

NEWSPAPERS AT THE TIME REPORTED
THE TOTAL NUMBER OF DECEASED

WAS ONLY 8.

IF DISEASE WAS TO BLAME,

WHY WERE SO MANY OF THE DEATHS
KEPT SECRET?

SO THIS PARTICULAR DOCUMENT
POINTS TO 57 PEOPLE DYING HERE.

BUT THAT LEAVES 49 BODIES
THAT ARE MISSING.

WHERE ARE THEY?

AND WHY WOULD THEY HAVE TRIED
TO COVER UP THIS INCIDENT?

UH, THAT'S A GOOD QUESTION.
WE INTEND TO FIND OUT.

TO HELP US SEARCH
FOR NEW CLUES,

WE'RE BRINGING IN BILL'S
BROTHER, FRANK WATSON,

AND GEOPHYSICIST TIM BECHTEL.

- HEY, TIM, FRANK.
- HEY, GUYS.

THE THREE MADE
A STUNNING DISCOVERY HERE

A FEW YEARS BACK
USING GROUND-PENETRATING RADAR,

OR GPR.

WHILE MAPPING THE AREA'S
SUBTERRANEAN STRUCTURE,

THEY HIT UPON
SOMETHING STRANGE.

WE FOUND AN ANOMALY RIGHT HERE
AT A VERY RESISTIVE BLOB

DOWN INSIDE
THE EMBANKMENT.

THAT ANOMALY TURNED OUT TO BE
THE REMAINS OF EIGHT LABORERS,

PRESUMABLY THE ONES WHOSE
DEATHS WERE MADE PUBLIC.

AND YOU FOUND EIGHT BODIES?

WE FOUND THE-- THE SIX--
SIX BODIES AND--

AND ANOTHER COFFIN.

AND THEN A STAIN OF A COFFIN.

MORE OF A STAIN.

YES.

THE FIND REIGNITED
THE LONG-FORGOTTEN MYSTERY

AND OFFERED
BREAKTHROUGH FORENSIC EVIDENCE

THAT COULD REVEAL,
FOR THE FIRST TIME,

HOW THESE WORKERS DIED.

BILL AND FRANK EXPLAIN
HOW A LETTER

FROM THEIR GRANDFATHER'S
SECRET FILES

LED THEM TO THE GRAVES.

"THEY WERE BURIED WERE
THEY WERE MAKING THE FILL."

PENNED BY THE SON
OF A FORMER RAILROAD EMPLOYEE,

THE NOTE SUGGESTED
THE MASS GRAVE

WAS HIDDEN
IN THE RAISED BED OF SOIL

THAT WAS BUILT FOR THE TRACKS.

WE REALIZED, "WAIT A MINUTE.

THESE GUYS ARE
IN THE EMBANKMENT."

AT LEAST EIGHT OF THEM WERE.

BUT THERE WAS NO TRACE
OF THE OTHER LABORERS

WHOSE DEATHS WERE KEPT QUIET.

SO WHAT I DON'T UNDERSTAND
IS YOU'VE GOT EIGHT BODIES.

THOSE WERE ONES THAT
YOU SAID WERE IN COFFINS.

SO WHERE'S
THE OTHER 49 BODIES?

WE HAVE A SUSPICION.

TIM BELIEVES THE ANSWER TO THE
MYSTERY GOES BACK TO THE 1870s,

40 YEARS AFTER THE DEATHS,

WHEN THE RAIL LINE WAS IMPROVED
FOR MODERN TRAINS.

SO TO TAKE THIS CURVE OUT,

IN 1870, THEY MOVED
THE RAILROAD BED

JUST A LITTLE BIT
TO THE NORTH.

UH-HUH.

AND, OF COURSE,
TO BUILD THAT BED,

THE EASIEST MATERIAL TO USE
IS THE 1832 MATERIAL.

STUFF THAT WAS ALREADY LOOSE.

THIS IS ALREADY LOOSE.
IT'S BEEN DUG.

SO YOU DIG THIS OUT
AND MOVE IT OVER.

TIM SUSPECTS THAT THE LABORERS

STUMBLED ACROSS ALL 57 BODIES

WHILE DIGGING INTO
THE OLD EMBANKMENT.

THE WORKERS WOULD'VE FOUND
EIGHT OF THE BODIES IN CASKETS.

AND IT SEEMS THEY
LEFT THOSE UNTOUCHED.

SO THOSE EIGHT WERE BURIED IN
A PROPER IRISH CATHOLIC FASHION.

THEY WERE IN COFFINS.

BUT TIM THINKS
THAT OUT OF RESPECT,

THEY REBURIED THE OTHERS
SOMEWHERE ELSE.

BUT WHERE?

IS THAT WHAT I THINK IT IS?

WILL OUR HIGH-TECH TOOLS
FINALLY REVEAL

WHERE THE BODES
WERE SECRETLY STASHED?

IS THAT IT?

IF SO, WE'LL BE
ONE BIG STEP CLOSER

TO FIGURING OUT EXACTLY HOW
THESE WORKERS DIED

AND WHY THEIR DEATHS
WERE NEVER REPORTED.

WERE THEY JUST VICTIMS
OF DISEASE

WHO WERE SWEPT UNDER THE RUG?

OR IS THERE SOMETHING
MORE SINISTER TO THIS STORY

THAT COULD POINT TO A DARK
CHAPTER IN AMERICA'S PAST?

YOU'RE SAYING THERE'S EVIDENCE
THIS PROBABLY WASN'T CHOLERA.

NO.

AND LATER, I'LL HEAD
TO THE BLUE RIDGE MOUNTAINS,

WHERE AN ICONIC LANDMARK
MADE FAMOUS

BY THE FILM "DIRTY DANCING"
HAS SUDDENLY DISAPPEARED.

THIS, RIGHT HERE,
IS A LITTLE SECTION OF WATER

THAT REMAINS OF THIS LAKE.

TO INVESTIGATE,
I'LL SEND AN R.O.V.

INTO WHAT'S LEFT OF
THE VANISHING LAKE IN ATTEMPT

TO SOLVE THIS
PERPLEXING MYSTERY.

OH, MY GOD.
OH, MY GOD!

I'M EXPLORING A STRETCH
OF WOODS KNOWN AS DUFFY'S CUT,

WHERE 57 IRISH RAILROAD WORKERS
MYSTERIOUSLY PERISHED.

SO FAR, A TEAM OF HISTORIANS

AND SCIENTISTS
HAVE RECOVERED

WHAT APPEARED TO BE REMAINS
OF THE EIGHT LABORERS

WHOSE DEATHS WERE REPORTED
IN THE PAPERS.

GEOPHYSICIST TIM
BECHTEL SUSPECTS

THAT IN THE 1870s,

THE OTHER 49 WERE
REBURIED ELSEWHERE

TO MAKE ROOM
FOR A NEW SET OF TRACKS.

AND THEY HIT THE MASS GRAVE.

AND THAT WOULD'VE
FREAKED THEM OUT.

IF WE CAN FIGURE OUT WHERE
THE MISSING MEN WERE MOVED TO,

MAYBE WE CAN FIND NEW EVIDENCE

THAT WILL TELL US
HOW THEY DIED

AND WHY THEIR DEATHS
WERE COVERED UP.

THE GRAVE MAY BE
TOO DEEP FOR GPR

TO ACCURATELY DETECT IT.

SO WE'RE TURNING TO ELECTRICAL
RESISTIVITY TOMOGRAPHY,

OR E.R.T., WHICH CAN PENETRATE
TO GREATER DEPTHS.

TIM AND HIS ASSISTANT, MARIAN,

SET UP THEIR E.R.T. GEAR
NEAR THE MEMORIAL WALL,

WHICH WAS ERECTED IN HONOR
OF THE WORKERS DECADES LATER.

TIM THINKS IT COULD
MARK THE SPOT

WHERE THE LOST VICTIMS
WERE REINTERRED.

PUT 'EM ON THE BOTTOM SIDE?

ANYWHERE, AS LONG AS THERE'S
GOOD METAL-TO-METAL CONTACT.

WITH E.R.T., A CURRENT
IS INJECTED INTO THE GROUND

BETWEEN A SET OF ELECTRODES.

OKAY. THAT'S SET.

AND NOW, WE HAVE THIS GRID
OF ELECTRODES COVERING

THIS WHOLE AREA
ALL CONNECTED BY CABLES.

WE HAVE 56 ELECTRODES.

YES.

AND WE WANT TO SEND
ELECTRICAL CURRENT

BETWEEN EVERY
CONCEIVABLE PAIR.

BY ANALYZING HOW
THE ELECTRICAL PULSES TRAVEL

BETWEEN VARIOUS POINTS,

WE CAN BUILD A PICTURE OF HOW
RESISTIVE THE GROUND IS

AND IDENTIFY ANY ANOMALIES THAT
COULD BE SIGNS OF A MASS GRAVE.

WE SEND CURRENTS THROUGH
IN ALL DIFFERENT DIRECTIONS,

JUST EVERY PATTERN
CONCEIVABLE.

AND THEN WE'RE GOING TO BE ABLE
TO CALCULATE FROM THAT

THE DISTRIBUTION
OF THE ELECTRICAL RESISTIVITY

IN THE EARTH.

THIS IS A GREAT WAY
TO PEER BENEATH THE SOIL.

BUT TIM SUSPECTS THAT EVEN

IF THIS IS THE LOCATION
OF THE MASS GRAVE,

WE MAY NOT FIND ANY BODIES

BECAUSE IF THE 49 WORKERS
WERE DUG UP

AND REINTERRED DECADES
AFTER THEIR DEATHS,

THEY MAY HAVE FULLY
DECOMPOSED BY NOW.

DURING THAT PERIOD, THEY'RE
EXPOSED TO THE ATMOSPHERE,

TO MOISTURE AND OXYGEN.

SO THAT'S GOING TO START

THE DECAY PROCESS
ALL OVER AGAIN.

SO WE'RE ALSO SEARCHING
FOR CAVITIES OF AIR

WHERE THE REMAINS
COULD ONCE HAVE BEEN

BECAUSE THE GROUND SHOULD'VE
HARDENED AROUND THE REMAINS

AND KEPT ITS SHAPE.

AS IT DECAYS AND COLLAPSES,

IT'S PROBABLY GOING TO LEAVE
SOME AIRSPACE BEHIND.

RIGHT.

BIG ELECTRICALLY
RESISTIVE BLOB.

CURRENTS FLOW EASILY
THROUGH DAMP SOIL

BUT ARE RESISTIVE WHEN PASSING
THROUGH LARGE VOIDS.

OKAY.

THIS IS SHOWING US THE POSITIONS
OF THE ELECTRODES.

- BUT, I MEAN, THIS IS RAW DATA.
- YEAH.

WE DON'T KNOW ANYTHING
ABOUT THE SUBSURFACE.

BUT THEN IT'S VERY SIMPLE
BECAUSE WHAT WE CAN DO

IS RUN THE ALGORITHM.

THE DATA COLLECTED
FROM THE CURRENTS CREATES

A DETAILED 3-D MAP
OF THE GROUND.

THIS COLOR SCALE IS
SHOWING ITS RESISTIVITY,

RED BEING RESISTIVE.

THIS CORNER IS OVER HERE.

AND THIS CORNER
IS OVER THERE.

SO RESISTIVE--
WE'VE GOT A RESISTIVE BLOB.

RIGHT THERE.
RIGHT THERE, THERE'S SOMETHING.

AND THAT BLOB LOOKS A LOT

LIKE A LARGE AIR CAVITY
IN THE EARTH,

ONE POTENTIALLY LARGE ENOUGH
TO CONTAIN A MASS GRAVE.

LET ME COUNT IN
FROM THE ELECTRODES.

AND IT LOOKS LIKE IT'S GONNA
BE TWO OR SO IN.

YEAH.
IT'S RIGHT ABOUT HERE.

HOLY MOLY.

THERE'S A VERY LARGE
RESISTIVE MASS 20 FEET DOWN.

THAT'S, LIKE, ALMOST
20-FEET-BY-20-FEET.

YEAH. AND IT-- IT NEEDS
TO BE BIG FOR THE REMAINS

OF 49 HUMANS.

IT'S A GEOPHYSICAL ANOMALY
THAT'S PERFECTLY CONSISTENT

WITH WHAT WE'RE LOOKING FOR.

THE SITE LIES ON PRIVATE
RAILROAD PROPERTY.

AND WE CAN'T GET
CLEARANCE TO DIG

BECAUSE OF ITS CLOSE PROXIMITY
TO AN ACTIVE RAIL LINE.

SO WE WON'T BE ABLE
TO CONFIRM FOR SURE

WHETHER THIS IS THE SITE
OF THE MASS GRAVE.

BUT I CAN STILL INVESTIGATE
THE BROADER MYSTERY.

WHY WOULD RAILROAD OFFICIALS
TRY TO CONCEAL THESE 49 DEATHS

UNLESS THEY HAD
SOMETHING TO HIDE?

ACCORDING TO THE COMPANY'S
RECENTLY UNEARTHED SECRET FILES,

ALL 57 WORKERS PERISHED
FROM CHOLERA,

A BACTERIAL INFECTION
THAT CAUSES KIDNEY FAILURE

AND SEVERE DEHYDRATION.

CHOLERA IS TYPICALLY SPREAD
THROUGH TAINTED FOOD AND WATER.

IF LEFT UNTREATED,
IT CAN KILL WITHIN HOURS.

CHOLERA EPIDEMICS WERE PREVALENT
IN THE UNITED STATES

DURING THE 19th CENTURY.

BUT IMPROVEMENTS IN SANITATION

AND MEDICAL TREATMENT
HAVE MADE IT VERY RARE TODAY.

SO IS DISEASE THE REAL CULPRIT
BEHIND THESE DEATHS?

SOME BELIEVE THAT STORY
JUST DOESN'T ADD UP.

WE RESCANNED THE AREA,

AND I THINK WE FOUND
A MASS GRAVE SITE.

PHYSICAL ANTHROPOLOGIST
JANET MONGE

HAS CLOSELY EXAMINED
THE REMAINS OF THE FEW

THAT HAVE BEEN RECOVERED
FROM DUFFY'S CUT.

AND SHE'S SKEPTICAL
THAT ALL 57 WORKERS

WHO WENT MISSING COULD'VE
SUCCUMBED TO THE SAME ILLNESS.

IN THE 1830s, CHOLERA'S
FATALITY RATE WAS ABOUT 60%.

IT REALLY CANNOT BE SPONTANEOUS,
SIMULTANEOUS DEATH

OF ALL 50-PLUS PEOPLE
FROM CHOLERA.

- RIGHT.
- IT-- IT CAN'T BE.

OR IT WOULD HAVE
A MORTALITY FROM CHOLERA

WHICH IS NOT MATCHED
ANYWHERE ELSE IN THE WORLD.

IN FACT, JANET SUSPECTS
THERE MAY BE

A MORE SINISTER EXPLANATION
FOR THIS MASS DEATH.

THE ISSUE IS, THOUGH,
HOW DID THEY ACTUALLY DIE?

THE REAL SORT OF POWERFUL
BIT OF DATA

IS THAT ALL OF THE INDIVIDUALS
THAT WE EXCAVATED

HAD BLUNT-FORCE TRAUMA

OR ACTUALLY
BULLET-BASED TRAUMA.

WHAT REALLY HAPPENED
TO THESE 57 WORKERS?

USING CT SCANS,
WE'LL TAKE A CLOSER LOOK

AT THE RECOVERED REMAINS
IN THE SEARCH FOR NEW CLUES

ABOUT THE DARK SECRETS
OF DUFFY'S CUT.

I'M INVESTIGATING
THE STRANGE CASE

OF 57 IRISH IMMIGRANTS

WHO MYSTERIOUSLY PERISHED
WHILE BUILDING A RAILROAD

AT PENNSYLVANIA'S DUFFY'S CUT.

INTERNAL COMPANY REPORTS CLAIMED
THAT CHOLERA KILLED THEM ALL.

BUT PHYSICAL ANTHROPOLOGIST
JANET MONGE SUSPECTS

THERE'S A MORE
DISTURBING EXPLANATION.

MOST OF THE BONES THAT WERE
EXHUMED AT DUFFY'S CUT

HAVE NOW BEEN PROPERLY REBURIED.

SO JANET PULLS UP
RECONSTRUCTIONS

PRODUCED FROM CT SCANS.

ONE OF THE SKULLS SHOWS
A VERY DISTINCT HOLE.

WE FOUND METAL FRAGMENTS
INSIDE OF THE SKULL.

NO WAY!
REALLY?

SO WE DO KNOW THAT IT WAS
A BULLET HOLE. ABSOLUTELY.

AND THIS IS, ACTUALLY,
PROBABLY AN AX WOUND.

JANET SEES COMPELLING EVIDENCE
THAT THEY WERE INFLICTED

WHILE THE VICTIMS
WERE STILL ALIVE.

AFTER THE PERSON WAS DEAD,

THIS WOULD'VE
SHATTERED THE SKULL.

BUT, NO.
THIS IS JUST BROKE THE SKULL,

LIKE YOU WOULD BREAK
A LIVING TISSUE.

BONE IS ACTUALLY
KIND OF ELASTIC.

RIGHT.

IT'S 40% COLLAGEN.

SO WHEN SOMEONE'S
HIT ON THE HEAD,

AND THE PERSON IS ALIVE...

WHOA.

THE BONE ACTUALLY DOESN'T
FRACTURE OR FALL APART.

IT DISTORTS.

THE REAL SORT OF POWERFUL
BIT OF DATA

IS THAT
ALL OF THE INDIVIDUALS

THAT WE EXCAVATED
HAVE BLUNT-FORCE TRAUMA

OR ACTUALLY
BULLET-BASED TRAUMA.

WOW.

YOU KNOW, WHEN YOU START TO LOOK
AT THOSE KINDS OF OUTCOMES...

RIGHT.

...THEN THE CHANCES OF THIS
BEING A RANDOM ACCIDENT

OR ANYTHING LIKE THAT,
OF COURSE,

BECOMES MORE
AND MORE REMOTE.

THIS IS A STUNNING
DEVELOPMENT--

PHYSICAL EVIDENCE OF
A MASS MURDER IN PENNSYLVANIA

THAT WAS NEVER REPORTED,
MUCH LESS PROSECUTED.

BUT WHO WOULD KILL
THESE LABORERS AND WHY?

IT DOESN'T BENEFIT
THE RAILROAD TO KILL THEM.

MM-HMM.

ACTUALLY, THEY WOULD
WANT THEIR WORKERS.

YEAH. I'M SURE
IT WASN'T RAILWAY PEOPLE.

IT WAS LOCALS IN THE TOWN.

AS JANET EXPLAINS,

THE GAELIC-SPEAKING
IRISH IMMIGRANTS OF THE TIME

WERE OFTEN TREATED
AS UNWANTED STRANGERS.

BASICALLY,
WHAT'S HAPPENING

IS THESE IRISH FOLKS
COME INTO TOWN.

THEY DON'T SPEAK ENGLISH.

AND THEY'RE ALSO FOREIGN
IN THEIR RELIGION.

THEY'RE CATHOLIC.
AND THIS IS, YOU KNOW,

A TIME WHEN
THERE'S LOTS OF ISSUES

BETWEEN PROTESTANTS
AND CATHOLICS.

BUT WAS MERE INTOLERANCE ENOUGH
OF A MOTIVATION FOR MASS MURDER?

IT SEEMS LIKE THERE HAS
TO BE MORE TO THE STORY.

PIECING TOGETHER THE EVIDENCE
FROM THE RECOVERED REMAINS

AND HISTORICAL RECORDS,

JANET AND OTHERS HAVE
COME UP WITH A THEORY.

WHEN A CHOLERA EPIDEMIC
SWEPT THROUGH THEIR CAMP,

SOME OF THE IMMIGRANTS
MAY HAVE TRIED TO ESCAPE

AN IMPOSED QUARANTINE.

BUT THEY WERE INTERCEPTED
AND KILLED BY LOCAL VIGILANTES

TRYING TO PROTECT THE COMMUNITY

FROM THE SPREAD OF THE DISEASE.

THE THINKING IS,
"GO AFTER THE INTRUDERS."

THEY DON'T KNOW
THE NATURE OF DISEASE.

THERE'S NO SENSE
OF HOW IT'S TRANSMITTED.

YOU SUDDENLY GET SICK.

SO WHY NOT BLAME IT,
BASICALLY,

ON THE NEW GUYS IN TOWN?

AN AX WOUND
IS AN INTENSE WOUND.

YEAH,
SUPER-VIOLENT CRIMES.

JANET BELIEVES THE EIGHT VICTIMS
WHO MAY HAVE TRIED TO FLEE

WERE BROUGHT BACK IN COFFINS
TO DUFFY'S CUT.

BUT WHAT ABOUT THOSE OTHER 49,

THE NAMELESS DOZENS WHOSE DEATHS
WERE SWEPT UNDER THE RUG?

JANET BELIEVES THEY PROBABLY
PERISHED SOON AFTER.

BUT WITHOUT THEIR
PHYSICAL REMAINS,

WE MAY NEVER KNOW WHETHER
THEY WERE VICTIMS OF DISEASE,

MURDER,
OR A COMBINATION OF BOTH.

BASED ON WHAT SHE'S SEEN
IN THE EXISTING SKULLS,

JANET SUSPECTS THESE MEN
WERE ALL MURDERED, TOO,

AND THAT RAILROAD OFFICIALS
COVERED UP THE KILLINGS

TO PROTECT THEIR EFFORTS
TO RECRUIT MORE CHEAP LABOR.

BECAUSE THEY ABSOLUTELY
HAVE A MANDATE--

BUILD THIS PART OF THE RAILROAD
FOR X AMOUNT OF DOLLARS

IN X AMOUNT OF TIME.

THE STORY OF THESE WORKERS
WAS A TRAGIC CIRCUMSTANCE

AND A DARK, LOST CHAPTER
IN PENNSYLVANIA HISTORY.

AND THOUGH WE MAY
NEVER KNOW FOR CERTAIN

WHAT REALLY HAPPENED
TO THE WORKERS,

JANET AND THE OTHERS
WHO'VE WORKED TO CRACK THE CASE

TAKE SOME COMFORT IN KNOWING
THAT AFTER NEARLY TWO CENTURIES,

THEIR EFFORTS HAVE BROUGHT
THIS LONG-FORGOTTEN STORY

TO LIGHT ONCE AGAIN.

IT'S REALLY
A TRIBUTE TO THEM.

THEY DIED DOING HARD WORK,

DOING THEIR JOB,
AND MAKING AMERICA.

I MEAN, THESE ARE THE PEOPLE
THAT MADE AMERICA.

NOW, FROM THIS HALLOWED GROUND
OUTSIDE OF PHILLY,

I'M HEADING SOUTH

TO THE BLUE RIDGE MOUNTAINS
OF VIRGINIA,

WHERE THE FILMING LOCATION
OF AN ICONIC MOVIE

IS STEEPED IN MYSTERY.

IT WAS A LAKE USED AS A LOCATION
IN THE ICONIC FILM,

"DIRTY DANCING,"

AND THE PERFECT SUMMER RETREAT
BOTH ON AND OFF-SCREEN.

FOR DECADES, THOUSANDS
OF FAMILIES MADE MOUNTAIN LAKE

A PART OF THEIR
SUMMER TRADITION.

THEN IN 2002, SOMETHING
BIZARRE STARTING HAPPENING.

THE LAKE LEVELS BEGAN
TO DROP DRAMATICALLY.

AND BY 2008, IT HAD
COMPLETELY VANISHED.

NO ONE COULD EXPLAIN
HOW IT HAPPENED.

EVAPORATION ALONE COULD
NEVER ACCOUNT

FOR SUCH A DRAMATIC DROP.

SO THE QUESTION WAS,
WHERE DID ALL THE WATER GO?

THIS, RIGHT HERE,
IS THE LITTLE SECTION OF WATER

THAT REMAINS OF THIS LAKE,
THE VANISHING LAKE.

IT'S ALMOST HARD TO IMAGINE

THAT 80 FEET OVER OUR HEAD

WAS THE OLD SURFACE
OF THIS LAKE.

THIS IS, LIKE,
BASICALLY AT THE BOTTOM

OF WHERE THE OLD LAKE WAS.

WHAT MAKES THIS PUZZLE
EVEN WEIRDER

IS THAT THE LAKE STARTED
TO COME BACK

AND THEN STOPPED FILLING AGAIN.

TODAY, IT'S ONLY
ABOUT 30 PERCENT

AS DEEP AS IT WAS
WHEN IT WAS FULL.

SO WHAT ON EARTH
IS GOING ON HERE?

WHEN THIS 47-ACRE
LAKE DRIED UP IN 2008,

BUSINESS DID, TOO, AND,
WITH IT, MANY LOCAL JOBS,

TOURISM DOLLARS, AND COUNTLESS
FAMILY MEMORIES YET TO BE MADE.

AND AS EMPLOYEES
FROM THE LODGE CAN ATTEST,

IT WAS PROBABLY THE WORST TIME

FOR SOMETHING
LIKE THIS TO HAPPEN.

NOT ONLY DID OUR LAKE GO AWAY.
THE RECESSION WAS IN, TOO.

AND BETWEEN THE TWO THINGS,
WE WERE DEVASTATED.

WE DIDN'T KNOW WHAT TO DO.

IT'S VERY DEPRESSING TO ME
TO SEE THE LAKE THE WAY IT IS,

BUT I'M IN HOPES
THAT EVENTUALLY, ONE DAY,

I'LL SEE IT FULL AGAIN.

NO ONE HERE IS SURE
WHY THE LAKE DISAPPEARED.

BUT IF THAT MYSTERY
COULD BE SOLVED,

COULD IT LEAD TO A SOLUTION
TO BRING MOUNTAIN LAKE BACK?

TO FIND OUT, I'M MEETING UP
WITH A TEAM OF SPECIALISTS

WHO ARE WORKING
TO SOLVE THE MYSTERY.

TOGETHER, WE'LL DEPLOY
AN R.O.V. TO THE BOTTOM

OF WHAT'S LEFT OF THIS LAKE...

R.O.V. IS GOING
IN THE WATER.

...TO SEARCH FOR CLUES
ABOUT WHAT CAUSED

A 6,000-YEAR-OLD LAKE
TO SUDDENLY VANISH.

WHOA!
OH, MY GOSH!

I'M AT MOUNTAIN LAKE IN VIRGINIA

TRYING TO SOLVE
A PERPLEXING MYSTERY.

WHAT CAUSED THIS
ONCE-FLOURISHING BODY OF WATER

TO SUDDENLY DISAPPEAR?

AND WHERE DID
ALL THE WATER GO?

TO TRY TO ANSWER
THESE QUESTIONS,

I'M MEETING UP
WITH A PAIR OF SPECIALISTS.

GEOPHYSICIST TIM BECHTEL,

WHO JOINED ME EARLIER
TO INVESTIGATE DUFFY'S CUT,

IS AN EXPERT ON
UNDERGROUND SENSING TECHNOLOGY.

AND TEAM GEOLOGIST
"PAKI" STEPHENSON

PILOTED THE INITIAL R.O.V.
INSPECTION OF THE LAKE BOTTOM

WHICH CONFIRMED
SOMETHING STARTLING.

WATER WAS LEAKING OUT
THROUGH FOUR LARGE FUNNELS

AT THE BOTTOM.

WE SET UP ON
A PONTOON BOAT

MOORED JUST OFF
WHERE THEY WERE SPOTTED.

SOMEWHERE OUT HERE
ARE THOSE OLD VENTS.

AND WHAT WE WANT TO DO FIRST

IS WE WANT TO SEND AN R.O.V.
DOWN INTO THE WATER.

WE WANT TO SCOUR THE BOTTOM
FOR DIFFERENT AREAS

WHERE THE WATER
MIGHT BE FLOWING OUT.

PAKI, HERE, THINKS HE HAS
AN IDEA WHERE IT IS.

- YOU GOT IT, PAKI?
- I DO. WE'RE READY.

NO ONE HAS EXPLAINED FULLY

HOW THESE VENTS
COULD'VE DRAINED THE LAKE

OR WHERE THE WATER WENT.

I SEARCHED FOR OTHER LAKES
THAT MIGHT OFFER A CLUE

AND I CAME ACROSS
OREGON'S LOST LAKE.

LAST WINTER, IT WAS
ONE AND A HALF TIMES BIGGER

THAN MOUNTAIN LAKE,
BUT BY THE FOLLOWING SUMMER,

IT HAD DISAPPEARED COMPLETELY.

THE REASON-- MULTIPLE OPENINGS
IN THE LAKE BED

THAT DRAIN THE WATER
OUT LIKE PLUGHOLES.

BUT THERE ARE
FUNDAMENTAL DIFFERENCES

BETWEEN LOST LAKE
AND MOUNTAIN LAKE.

LOST LAKE GOES THROUGH
THE SAME CYCLE EVERY YEAR.

THE PLUGHOLES ARE LAVA TUBES
THOUSANDS OF YEARS OLD

THAT EMPTY INTO MAGMA CHAMBERS
DEEP UNDERGROUND.

IN WINTER, THERE'S ENOUGH RAIN

AND SNOWFALL TO BALANCE
THE OUTFLOW THROUGH THE TUBES.

IN SUMMER, IT DRAINS DRY.

BUT MOUNTAIN LAKE
NEVER FLUCTUATED LIKE THIS,

AT LEAST IN RECENT MEMORY,
BEFORE IT SUDDENLY DISAPPEARED.

SCIENTISTS BELIEVED IT FORMED
ROUGHLY 6,000 YEARS AGO

WHEN A FEEDER STREAM
BEGAN TO COLLECT HERE

IN A NATURAL POOL OF WATER,
FORMING A LAKE.

AT 3,800 FEET ABOVE SEA LEVEL,

MOUNTAIN LAKE
IS THE HIGHEST NATURAL LAKE

EAST OF THE MISSISSIPPI.

MOST LAKES IN THIS REGION
ARE MUCH CLOSER TO SEA LEVEL.

SO THE FACT THAT THIS LAKE
EVEN EXISTS HERE AT ALL

IS A MYSTERY IN ITSELF.

BUT THE LOCALS WHOSE LIVELIHOODS
HAVE DEPENDED ON IT FOR DECADES

WERE SURE GLAD IT DID.

THAT'S WHY WHEN
THE WATER DISAPPEARED,

THE LODGE'S OWNERS DECIDED

TO SEAL THE HOLES
IN THE LAKE BED SHUT

IN A DESPERATE BID
TO SAVE THE RESORT.

AND THEY CAME IN HERE
WITH HEAVY EQUIPMENT,

UH, EXCAVATORS
AND, UH, BULLDOZERS.

THEY DRAGGED DOWN
SOME OF THE MATERIAL

OFF THE FLANKS OF THE LAKE

AND FILLED UP
THOSE BIG FUNNELS.

AT FIRST, IT SEEMED LIKE
THEY HAD FOUND THE MAGIC BULLET

AND FIXED THE PROBLEM.

RAINFALL, UNDERGROUND SPRINGS,

AND THE FEEDER STREAM BEGAN
TO REFILL THE LAKE ONCE AGAIN.

EVEN THE FISH CAME BACK,

THOUGH NO ONE WAS
STOCKING THE LAKE.

BUT AS QUICKLY AS THE SOLUTION
SEEMED TO COME,

IT SUDDENLY STOPPED WORKING.

AND AS SOON AS THEY PULLED
THEIR EQUIPMENT OUT,

THE LAKE WAS RISING VERY FAST,
JUST LIKE THAT.

AND THEN IT STOPPED.

EVERYONE WAS STUMPED YET AGAIN,

AS IT SEEMED MOUNTAIN LAKE
HAD A MIND OF ITS OWN.

COULD NEW HOLES HAVE FORMED
SOMEWHERE ELSE IN THE LAKE BED?

AND IF SO, WHY?

- NOW WE SET THE R.O.V. UP.
- WE'RE READY.

THE FIRST STEP TO SOLVING
THIS MYSTERY IS TO CHECK

IF THE CLAY PLUGS
INSTALLED IN 2013 HELD

OR IF WATER IS STILL
DRAINING THROUGH THEM.

THAT'S WHERE
THE R.O.V. COMES IN.

ON THE FRONT OF THE R.O.V.,
WE HAVE A LITTLE CAMERA.

WE HAVE LIGHTS ON THE SIDE.

ONCE THE R.O.V. SETTLES,

THE BOTTOM OF THE LAKE
SHOULD BECOME CALM AND QUIET.

BUT IF PAKI STIRS UP SILT
WITH THE THRUSTERS,

AND THERE IS A LEAK,
WE WILL SEE A CLOUD

OF FAST-MOVING
SEDIMENTS STREAMING INTO IT.

R.O.V. IS GOING
IN THE WATER.

THAT THING CAN MOVE!
I LIKE IT.

OKAY.
WE'RE GOING DOWN.

WOW. CAN YOU PAN THAT CAMERA UP
JUST A LITTLE BIT?

PAKI DIRECTS THE R.O.V.
TO THE SPOTS THAT WERE PLUGGED.

AND IT LOOKS LIKE ALL'S QUIET.

ALL WE SEE IS THE LIGHT,
FLUFFY MUD JUST LAYING

IN A FLAT PLANE,

WHICH TELLS ME
THERE'S NO LEAKING.

IF ANY OF THOSE FUNNELS
HAD REOPENED UP,

WE WOULDN'T BE SEEING THIS.

SO THEN WHY ISN'T
THE LAKE FILLING UP?

SOMETHING ELSE HAS TO BE
GOING ON DOWN THERE.

SEARCHING FOR CLUES,

PAKI PILOTS OUR R.O.V.
AWAY FROM THE SEALED HOLES...

...AND MAKES A KEY DISCOVERY.

RIGHT NOW, I THINK
THE MUD LOOKS DIFFERENT.

WE'RE FINDING ROCKS.

I MEAN, IT LOOKS LIKE YOU GOT
A BOULDER FIELD OVER THERE.

LAKE BEDS ALMOST
NEVER LOOK LIKE THIS.

THAT COULD BE SIGNIFICANT.

IN FACT, IT REMINDS ME
OF SOMETHING I SAW

BEFORE I MET UP
WITH TIM AND PAKI.

WALKING AROUND THE SHORELINE
RIGHT AT THE MOMENT,

JUST TRYING TO GET A FEEL

FOR WHAT'S GOING ON HERE
IN THIS LAKE.

AS I SCOUTED THE SHORELINE,

I CAME TO A POINT
AT THE NORTHERN END

OF WHAT IS NOW THE LAKE BED,
CLOSE TO WHERE THE R.O.V. IS.

AND SOMETHING
STRUCK ME AS UNUSUAL.

IF YOU LOOK AT THIS ROCK...

I'VE WALKED AROUND
A LOT OF PLACES OUT WEST

AND THE GRAND CANYON.

AND YOU GET THESE KIND
OF SCREE FIELDS, RIGHT?

BIG BOULDERS THAT ARE OBLONG.

SCREE IS A COLLECTION
OF BROKEN ROCK FRAGMENTS

AT THE BASE OF MOUNTAINS
OR VALLEYS

THAT IS ACCUMULATED
THROUGH PERIODIC ROCK FALL

CAUSED BY LANDSLIDES
OR EARTHQUAKES.

AND IT COULD BE ANOTHER CLUE

ABOUT THE DISAPPEARANCE
OF VANISHING LAKE.

I MEAN, THIS DOES NOT
LOOK LIKE RIVER ROCK.

IT LOOKS A LITTLE BIT
LIKE THE SIDES

OF SOME OF THE HILLS
IN THE GRAND CANYON.

YOU MAY NOT THINK OF VIRGINIA
AS A HOTBED OF SEISMIC ACTIVITY.

BUT BELIEVE IT OR NOT, IT'S
A PRETTY ACTIVE EARTHQUAKE ZONE.

IN FACT, CENTRAL
AND SOUTHWESTERN VIRGINIA

AVERAGE A MAGNITUDE-5 EARTHQUAKE
OR LARGER EVERY 50 YEARS.

AND BETWEEN 2005 AND 2008,

WHEN THE LAKE BEGAN
TO NOTICEABLY DISAPPEAR,

11 MINOR EARTHQUAKES
RANGING FROM 2.0

TO 4.3 MAGNITUDE
WERE RECORDED IN THIS AREA.

SO COULD THESE TREMORS
BE CONNECTED, SOMEHOW,

TO MOUNTAIN LAKE'S
DISAPPEARANCE?

INTRIGUINGLY, THE R.O.V. IS NOW
REVEALING THAT THE BOULDER FIELD

I SAW NEXT TO THE LAKE CONTINUES

ALL THE WAY DOWN
TO THE LAKE BOTTOM.

THAT SUGGESTS AT LEAST PART
OF THIS LAKE WAS LIKELY AFFECTED

BY SEISMIC ACTIVITY.

SO WE MOVED THE R.O.V.
FROM THE OLD FUNNELS

THAT WERE REPAIRED.

SO WE HAVE IT KIND OF UP
CLOSE TO THE BANK.

THEN SOMETHING NEW APPEARS
ON THE MONITOR...

- WHOA.
- OH!

...A FAST-MOVING FLOW OF WATER

THAT LOOKS LIKE IT LEADS
TO AN OPENING.

THAT'S A HUGE HOLE, PAKI.

THIS IS STUNNING.

IT LOOKS LIKE MOUNTAIN LAKE
IS STILL VANISHING

RIGHT BEFORE OUR EYES.

I THINK WE FOUND A PLACE

WHERE WATER IS ACTIVELY
GETTING SUCKED OUT.

BUT WHERE'S THE WATER GOING?

AND CAN IT BE STOPPED
BEFORE IT'S TOO LATE?

I'M IN SOUTHWESTERN VIRGINIA

INVESTIGATING WHAT CAUSED

THIS ONCE-FLOURISHING MOUNTAIN
LAKE TO MYSTERIOUSLY VANISH.

AND OUR R.O.V. MAY HAVE
JUST UNCOVERED A KEY CLUE.

I THINK WE FOUND A PLACE

WHERE WATER IS ACTIVELY
GETTING SUCKED OUT.

THIS DISCOVERY OPENS UP
A WHOLE HOST OF QUESTIONS.

WHAT CAUSED THIS FUNNEL
TO OPEN UP?

COULD IT DRAIN THE LAKE
COMPLETELY DRY AGAIN?

AND WHERE IS ALL
THE WATER GOING?

ACTUALLY, THAT LOOKS LIKE
IT'S MOVING REALLY FAST...

IT DOES.
THAT IS GOOD FLOW.

I THINK I CAN GET
THE SUB IN THERE.

LET'S FOLLOW THE WATER.
LET'S SEE WHERE IT GOES.

I'VE YET TO FIGURE OUT
WHAT'S HAPPENED

TO THE MILLIONS OF GALLONS
OF WATER

THAT ONCE FILLED MOUNTAIN LAKE.

BUT LOCAL LORE HOLDS
A WILD THEORY.

WHEN I WAS A KID, YOU KNOW,
BEFORE I EVEN STARTED WORK HERE,

I'D ALWAYS HEARD, YOU KNOW,
THERE'S A LAKE UNDER THIS LAKE.

LIKE, MAYBE SOME GIANT
UNDERGROUND CAVERN...

EXACTLY. RIGHT.

...OR SOMETHING THAT'S
BASICALLY ACTING

AS A RESERVOIR
OR SOMETHING.

EXACTLY.

COULD THERE REALLY BE
A LAKE BENEATH THE LAKE?

APPARENTLY, ACCORDING
TO MY RESEARCH,

THERE ARE UNDERGROUND BODIES
OF WATER

BENEATH
OTHER SEISMICALLY ACTIVE AREAS.

A MASSIVE RESERVOIR
WAS RECENTLY DISCOVERED

BENEATH A VOLCANO
IN THE BOLIVIAN ANDES.

AND THERE ARE SIGNS
THAT SIMILAR WATER POCKETS LIE

BENEATH THE VOLCANIC AREAS

OF NEW ZEALAND
AND WASHINGTON STATE.

COULD AN UNDERGROUND
CAVERN ALSO EXIST

BENEATH MOUNTAIN LAKE?

AND COULD THAT BE WHERE
ALL THE WATER IS DRAINING TO?

I'M HOPING THE R.O.V.
CAN HELP ANSWER THAT QUESTION.

LOOK AT ALL THE SILT
FLOWING PAST YOU.

WOW.

BUT AS IT GETS CLOSER
TO THE POSSIBLE SOURCE

OF THE LEAK,
IT RUNS INTO TROUBLE.

I'M STUCK.

I CAN JUST A WIGGLE
A LITTLE BIT.

BUT I CAN'T GET OUT.

WHY DON'T YOU GIVE
A TUG ON THE UMBILICAL?

SEE IF WE GET YOU FREE.

HOW FAR DID I GO IN?

IT'S TIGHT.
I DON'T WANT TO PULL ON THIS.

TUGGING ON THE CABLES COULD
DAMAGE THE EQUIPMENT OR WORSE--

DETACH THE CABLE COMPLETELY,

LEAVING THE R.O.V.
STRANDED BELOW.

SO THERE'S ONLY ONE OPTION--

TO DIVE IN AN TRY TO RETRIEVE
THE R.O.V. BY HAND.

AND WHILE I'M DOWN THERE,

I CAN GET A CLOSE-UP
LOOK AT THE LAKE BOTTOM

AND SCAN FOR CLUES
ABOUT WHERE THE WATER IS GOING.

BUT I'LL NEED TO BE CAREFUL.

WE'RE CALLING IT A CAVE,
BUT WHAT IT REALLY IS

IS NESTED BOULDERS WITH
BIG OPENINGS BETWEEN THEM.

SURE.

SO WHEN YOU'RE RETRIEVING
THE R.O.V.,

DON'T MOVE ANY ROCKS 'CAUSE
WE DON'T WANT THIS TO SETTLE.

IF THIS WERE TO COLLAPSE,

IT COULD JUST TRAP
YOUR HAND OR SOMETHING.

IT'S FREEZING COLD,
VERY COLD.

YEAH. I'M GONNA JUST
SWIM ALONG THE LINE.

THE R.O.V.'S UMBILICAL
LEADS ME TOWARD THE TRAPPED SUB.

AND SURE ENOUGH,
THE CABLE IS CAUGHT.

I SEE THE R.O.V. LIGHTS.

IT'S WEDGED DEEP IN WHAT APPEARS
TO BE A KIND OF TUNNEL.

I'VE BEEN ON COUNTLESS DIVES
IN FRESHWATER LAKES.

AND THE TOPOGRAPHY
OF THIS LAKE BOTTOM

IS UNLIKE ANY
I'VE EVER ENCOUNTERED--

A SPRAWLING PILE
OF LARGE JAGGED ROCKS.

I HAVE TO WORK THE SUB LOOSE
WITHOUT DISLODGING ANY BOULDERS.

ONE WRONG MOVE COULD TRAP
THE R.O.V. OR ME UNDERNEATH.

AFTER SEVERAL MINUTES
OF TUGGING AND PULLING,

MISSION ACCOMPLISHED.

GOT IT!
WHOO.

THAT'S A PRETTY
GOOD-SIZED HOLE.

YOU COULD LOSE A LOT OF WATER

IN A LAKE LIKE THIS OVER
THE COURSE OF A DAY

OR A WEEK OR A MONTH.

BUT I WONDER,
HOW MUCH WATER, EXACTLY?

ENOUGH TO OFFSET THE INFLOW
FROM RAINFALL AND RUNOFF

AND DRAIN THE LAKE DRY AGAIN?

I HAVE A WAY TO FIND OUT.

I THINK THE NEXT STEP
IS TO GET SOME SORT

OF FLOW METER IN THERE
SO WE CAN FIGURE OUT

HOW MUCH WATER'S
PUMPING THROUGH.

WHAT WE'RE GONNA WANT YOU
TO DO IS GET THIS POSITIONED

SO THE IMPELLER'S
IN THE OPENING.

OKAY. SOUNDS GOOD.

BY MEASURING THE VELOCITY
OF THE FLUID OVER A KNOWN AREA,

THE FLOW METER CAN CALCULATE
JUST HOW MUCH WATER

IS MOVING THROUGH THE HOLE
THAT TRAPPED THE R.O.V.

AFTER SETTING
THE INSTRUMENT IN PLACE,

IT DOESN'T TAKE LONG
TO GET A READING.

THAT'S ABOUT A MILLION GALLONS
A DAY LEAVING THIS LAKE.

A MILLION GALLONS
IS MORE THAN ENOUGH

TO FILL AN ENTIRE
OLYMPIC-SIZE SWIMMING POOL.

AND THAT'S HOW MUCH WATER
IS LEAVING THIS LAKE EVERY DAY.

NOW, THE NEXT QUESTION IS,
WHERE IS IT ALL GOING?

THAT SEEMS LIKE
TOO MUCH WATER

TO MISS DRAINING OUT
TO THE SURFACE SOMEWHERE.

SO COULD THE LOCALS BE RIGHT?

COULD IT BE EMPTYING INTO SOME
DEEP SUBTERRANEAN CHASM?

I HAVE A THEORY.

BUT TO TEST IT...

- YOU READY, TIM?
- YEP.

I'LL NEED TO MAKE AN EARTHQUAKE.

I'M IN THE BLUE RIDGE MOUNTAINS

OF VIRGINIA, INVESTIGATING
WHY THE LAKE MADE FAMOUS

IN THE CLASSIC MOVIE
"DIRTY DANCING"

MYSTERIOUSLY DISAPPEARED

AND WHETHER IT CAN
BE BROUGHT BACK.

I DOVE TO A SPOT

WHERE ONE-MILLION GALLONS
OF WATER A DAY

IS FLOWING OUT THROUGH
THE LAKE BOTTOM.

NOW, I NEED TO FIGURE OUT
WHERE IT'S GOING.

COULD IT BE DRAINING INTO
AN UNDERGROUND CAVERN

AS SOME LOCALS BELIEVE?

THE LAKE BED AROUND THE LEAK
IS VERY UNUSUAL.

IT'S COVERED IN A FIELD
OF JAGGED BOULDERS

THAT COULD SIGNIFY
A VIOLENT SEISMIC PAST.

THE BOULDER FIELD
CONTINUES ALONG THE RIDGE

TO THE NORTH OF THE LAKE.

AND THE WATER SEEMS
TO BE DRAINING

TOWARD THE NORTH SIDE, TOO.

SO I'M GOING TO FOLLOW THE TRAIL

TO SEE IF IT OFFERS ANY CLUES

ABOUT WHAT'S GOING ON
UNDER THIS AREA.

NEAR THE TOP OF THE RIDGE
IS A GIANT BOULDER FIELD

KNOWN TO LOCALS
AS THE GARDEN OF THE GODS.

THIS ROCK RIGHT HERE

LOOKS A LOT LIKE WHAT
THE R.O.V. GOT CAUGHT IN.

THE QUESTION IS, WHAT'S GOING ON
BENEATH THIS ROCKY RIDGE?

I NEED A WAY TO PEER
DEEP UNDERGROUND.

SO I'M TEAMING UP AGAIN
WITH GEOPHYSICIST TIM BECHTEL.

HE HAS SOME SOPHISTICATED TECH

THAT WILL ALLOW US
TO ACTUALLY SEE

THE INTERNAL STRUCTURE
OF THE RIDGE.

SO WE SET UP
A SEISMIC REFRACTION SURVEY.

SEISMIC REFRACTION GIVES US
A SNAPSHOT OF THE SUBSTRATE

BY MEASURING ENERGY PULSES
THAT ARE SHOT INTO THE GROUND.

THESE PULSES TRAVEL
AT DIFFERENT SPEEDS

DEPENDING ON THE TYPE
OF MATERIAL

THEY'RE PASSING THROUGH.

WE'LL MEASURE THE SPEED
OF THESE PULSES WITH GEOPHONES

LAID OUT AT PRECISE LOCATIONS
ACROSS THE GROUND.

IMAGINE PUTTING YOUR EAR
TO THE GROUND

BUT LIKE 100,000 TIMES
MORE SENSITIVE.

AND THIS'LL ALLOW US TO FIND OUT

IF THE BOULDERS GO
ALL THE WAY DOWN,

OR IF IT'S JUST
HARD BEDROCK.

IF THE BOULDER FIELD DOES EXTEND

ALL THE WAY DOWN
BENEATH THE LAKE BOTTOM,

IT COULD OFFER AN ESCAPE PATH
FOR THE WATER THROUGH THE RIDGE.

BUT IF WE FIND ONLY BEDROCK,

THAT LIKELY MEANS
THE WATER DRAINS STRAIGHT DOWN.

AND THE LOCAL LORE OF A LAKE
UNDER THE LAKE

BECOMES A MORE DISTINCT
POSSIBILITY.

OKAY. SHALL WE?

YES.

MY JOB IN THIS EXPERIMENT
IS TO CREATE A MINI EARTHQUAKE.

ROB IS HITTING A STEEL PLATE
WITH THE SLEDGEHAMMER.

AND WE'RE TRACKING
THE SEISMIC WAVES FROM THAT.

YOU READY, TIM?

YEP!

WE'LL NEED ANOTHER.
HIT IT AGAIN.

OKAY.

NICE.

HOW'D IT GO?

LOOKS GREAT.

HEY, ROB. WE'VE GOT IT.

COME BACK
WHEN YOU'RE READY.

ALL RIGHT.

AS TIM CRUNCHES THE DATA,

AN ANSWER BEGINS TO EMERGE.

THIS IS BASICALLY
SHOWING A CROSS-SECTION

OF THE RIDGE HERE.

IN THE BLUE FIELD AT ONE END,

THE SEISMIC WAVES REVEAL
SOLID QUARTZITE BEDROCK.

BUT THE GREEN
AND YELLOW AREAS

INDICATE AN ENTIRELY
DIFFERENT TYPE OF MATERIAL

IN ONE SECTION OF THE RIDGE.

AND AS WE GET CLOSER OVER THERE
TO WHERE THAT BOULDER FIELD WAS,

THE MATERIALS IS JUST
NOT BEDROCK AT ALL.

IT'S MORE LOOSE
AND FRAGMENTED.

RIGHT.

ALL OF THOSE LARGE BOULDERS

THAT WE WERE LOOKING AT
OVER THERE

VERY LIKELY GO ALL THE WAY
TO THE GROUND TO, WHAT?

TWO HUNDRED FEET
DOWN OR SO.

SO THE RUBBLE FIELD
I SAW IN MY DIVE

WASN'T COVERING HOLES
IN THE LAKE BOTTOM.

THE RUBBLE FIELD
IS THE LAKE BOTTOM.

AND IT COULD HAVE DOZENS
OF CRACKS, CREVICES,

AND HOLES HIDDEN WITHIN IT

THAT LEAD ALL THE WAY THROUGH
THE RIDGE.

BUT IF THAT'S TRUE,
THE LAKE WATER

WOULD BE LEAKING OUT
SOMEWHERE ON THE OTHER SIDE.

SO I HEAD INTO THE WOODS
DOWNHILL OF THE RIDGE

TO HUNT FOR SIGNS
OF RUNNING WATER.

AFTER AND HOUR OF TRUDGING,
I'M ABOUT A MILE FROM THE LAKE.

AND THE WOODS ARE BONE-DRY.

I'M STARTING TO THINK

MAYBE THERE'S SOMETHING TO
THAT LOCAL LEGEND AFTER ALL.

BUT THEN...

WHOA!
LOOK AT THIS.

IT'S WATER COMING OUT.

NOT A WHOLE LOT.
COULD BE GROUND SEEPAGE.

BUT WE CAN TEST THE WATER.

IF I CAN TRACE THIS WATER
BACK TO THE LAKE,

THAT WOULD RULE OUT
THE UNDERGROUND CAVERN THEORY

AND FINALLY SOLVE THE MYSTERY OF

WHERE ALL THAT WATER
IS DISAPPEARING TO.

I GRAB A SAMPLE FROM THE STREAM

TO COMPARE IT
TO THE LAKE WATER...

STREAM WATER RIGHT HERE.

...AND DISCOVER
SOMETHING INTRIGUING.

THE PH LEVELS OF THE TWO SAMPLES
ARE A MATCH,

AND, MORE TELLINGLY,
SO ARE THE TDS LEVELS,

OR TOTAL DISSOLVED SOLIDS,

WHICH MEASURE THE AMOUNT
OF MINERALS DISSOLVED IN WATER.

TYPICALLY, WATER EMERGING
FROM UNDERGROUND

WOULD HAVE A HIGHER TDS
LEVEL THAN LAKE WATER

BECAUSE IT HAS MORE TIME
TO ABSORB DISSOLVED MINERALS.

BUT NOT HERE.

THAT IS ALMOST IDENTICAL TO
THE ONE WE FOUND IN THE STREAM.

SO THIS TELLS ME
THE WATER FROM THE LAKE

IS DRAINING STRAIGHT
THROUGH THE RIDGE

AND INTO THIS STREAM.

MOUNTAIN LAKE IS REALLY NOTHING
MORE THAN A TEMPORARY REST STOP

FOR RUNOFF HEADING DOWNHILL.

THIS DATA,
ALONG WITH OUR SEISMIC TEST

AND UNDERWATER EXPLORATION,

ALSO COMPLETES THE PICTURE

OF HOW THE LAKE FORMED
IN THE FIRST PLACE.

THOUSANDS OF YEARS AGO,
A LANDSLIDE,

PROBABLY TRIGGERED
BY AN EARTHQUAKE,

UNLEASHED A BEVY OF BOULDERS
INTO THIS VALLEY,

CREATING THE RIDGE
THAT FORMED THE NORTH SIDE

OF WHAT WOULD
BECOME MOUNTAIN LAKE.

AS THE FEEDER STREAM
CARRIED BRANCHES AND SILT

THROUGH THIS PILE
OF ROCKS, EVENTUALLY,

THEY FILLED IN THE CREVICES

AND CREATED A NATURAL DAM
FOR WATER TO POOL BEHIND.

BUT THAT DAM AND THIS LAKE
WERE NEVER BUILT TO LAST.

IT'S BASICALLY A RUBBLE PILE

THAT CONTINUALLY IS
GETTING CLOGGED AN UNCLOGGED.

SO THAT LEAVES
ONE FINAL QUESTION.

CAN THAT NATURAL DAM BE FIXED
AND MOUNTAIN LAKE BE SAVED?

WELL, NOT EXACTLY.

BUT IT CAN SAVE ITSELF.

SINCE MY VISIT,
FURTHER RESEARCH HAS REVEALED

THAT THIS PROCESS
OF FILLING AND DRAINING

IS ACTUALLY CYCLICAL.

AND THESE CYCLES EFFECTIVELY
FILTER OUT THE SEDIMENT

THAT BUILDS UP ON THE BOTTOM
THROUGH ITS NATURAL

PLUMBING SYSTEM UNDER THE RIDGE.

SO THE LODGE HAS DECIDED

NOT TO TRY TO SEAL THE LEAKS
ARTIFICIALLY,

BETTING THAT OVER TIME,
THE LAKE WILL HEAL ON ITS OWN.

WITH A LITTLE LUCK,

THERE STILL MAY BE GENERATIONS
OF SUMMER MEMORIES

TO BE MADE HERE.

MOUNTAIN LAKE HAS BEEN HIDING
ITS SECRETS FOR CENTURIES.

IT JUST NEEDED SCIENCE
TO DECODE THEM.