Natural World (1983–…): Season 15, Episode 11 - Natural World - full transcript

Are you wondering how healthy the food you are eating is? Check it - foodval.com
---
70 MILLION YEARS AGO,

DINOSAURS ROAMED THIS PART

OF THE SOUTHWESTERN
UNITED STATES.

THIS WAS ONCE
A REAL JURASSIC PARK.

FAR LARGER
THAN THAT FICTITIOUS LAND,

THIS WAS
AN ELEVATED PLATEAU

BIGGER THAN
THE BRITISH ISLES.

60 MILLION YEARS
AFTER THE DINOSAURS

HAD TURNED
TO DUST AND ROCK,

A GREAT RIVER
FLOWING FROM THE ROCKIES
ALTERED COURSE

AND DRAMATICALLY CHANGED
THIS FLAT PLATEAU.



IT SCOURED OUT ONE
OF THE BIGGEST CHANNELS
IN THE EARTH'S CRUST

CREATING THE GRAND CANYON.

FOR THREE MILLION YEARS
THE COLORADO RIVER

DUG INTO THE GREAT PLATEAU.

AT THE END
OF THAT GEOLOGICALLY BRIEF TIME

IT HAD CREATED ONE
OF THE SEVEN WONDERS
OF THE NATURAL WORLD.

THE FORMATION
OF THE GRAND CANYON

WOULD HAVE BEEN
SEEN BY ANCESTORS
OF THIS CHUCKWALLA.

MORE RECENT CHUCKWALLAS
WITNESSED THE ARRIVAL

OF CONCRETE MONSTERS.

TODAY, DAMS DOMINATE

WHERE ONCE DINOSAURS DID.

ALL THAT'S LEFT
OF THE PLATEAU DINOSAURS

ARE FOOTPRINTS
PRESERVED IN SOLID ROCK.



THE PLACE WHERE THEY LIVED
65 MILLION YEARS AGO

IS A PLACE WHERE OTHERS
NOW LIVE AND PLAY.

( Native American singing )

WAY DOWN BELOW RAVENS
AND BIGHORN SHEEP,

RIVER RUNNERS
TAKE ON THE CHALLENGE
OF SPECTACULAR RAPIDS.

BACK IN 1869,
JOHN WESLEY POWELL

WAS THE FIRST
TO RUN THE RIVER

AND EVER SINCE
SHEEP AND RAVENS

HAVE SHARED THEIR SPACE
WITH AN INCREASING NUMBER

OF RIVER RUNNERS FOLLOWING
HIS EPIC PATH.

THIS IS A PLACE
OF CONSTANT SURPRISE

AND OF EXTREMES.

ON THE NORTHERN CANYON RIM,

WINTER STORMS DROP SNOW.

IT CAN START IN OCTOBER
AND GO ON UNTIL JUNE.

THE CANYON HAS A HOST
OF MICROCLIMATES

SUPPORTING AN ASTONISHING
RANGE OF SPECIES,

FROM PLANTS
LIKE HEAT-LOVING CACTUS

TO DOWNY WOODPECKERS,

ABLE TO SURVIVE
AT THIS END OF THE CANYON'S
CLIMATIC EXTREMES.

FAR DOWN
ON THE CANYON FLOOR

THERE'S ANOTHER WORLD,
WHERE SNOW NEVER FALLS.

EACH SNOWFLAKE MELTS
BEFORE IT CAN REACH THE BOTTOM,

ONE MILE DOWN.

IT GETS PROGRESSIVELY WARMER
TOWARDS THE CANYON FLOOR,

AS MUCH AS 16 DEGREES
CENTIGRADE.

SUCH EXTREMES
ARE NOTHING TO THE RAVEN

WHICH EFFORTLESSLY SPANS
THE DISTANCE FROM RIM TO FLOOR,

WHERE PRICKLY PEARS
AND OTHER TYPICAL
DESERT PLANTS,

LIKE OCOTILLOS, FLOURISH.

AND THIS IS WHERE
OUR SMALL DINOSAUR REPLICAS
FLOURISH, TOO.

OTHER LIZARDS SHARE
THE CHUCKWALLA'S HOME.

LIKE ALL
COLD-BLOODED REPTILES,

THE COLLARED LIZARD NEEDS HEAT
BEFORE IT CAN GET GOING.

THESE LITTLE LIZARDS
MAY NOT BE A PATCH

ON THE GIGANTIC DINOSAURS
WHOSE LAND THIS ONCE WAS,

BUT THEIR BASIC INSTINCTS
ARE IDENTICAL.

IGNORING THE DRAMA,
THE CHUCKWALLA SOAKS UP
THE ARIZONA SUN.

IT'S HARD TO IMAGINE
THE GRAND CANYON.

AS MUCH AS 15 MILES
AT ITS WIDEST

AND OVER 6,000 FEET
AT ITS DEEPEST,

THIS GEOLOGICAL MARVEL
IS A COMPLEX WORLD

OF GORGES
AND TOWERING CLIFFS

CARVED BY BILLIONS
OF GALLONS OF WATER.

FEW ANIMALS CAN EXPLOIT
SUCH A PLACE

OF DIZZYING CLIFFS
AND HOSTILE ROCK FACES.

BIGHORN SHEEP
ARE COMPLETELY AT HOME

IN PLACES WHERE NOTHING ELSE
COULD GET A TOE-HOLD.

GRAZING IS SPARSE,

BUT THEY LIVE
A RELATIVELY UNDISTURBED LIFE

PROTECTED BY
THE HUGE NATURAL BARRIER
THAT IS THEIR HOME.

AS IT TRAVELS
THE INCREDIBLE 277 MILE LENGTH
OF THE GRAND CANYON,

THE COLORADO RIVER
IS JOINED BY OTHERS,

LIKE THE LITTLE COLORADO,

FLOWING LIQUID TURQUOISE
FROM MINERALS SCOURED
FROM THE ROCK.

THE LITTLE COLORADO'S FLOW
REMAINS UNALTERED BY THE DAMS

WHICH HAVE CHANGED THE NATURE
OF THE LARGER RIVER.

THE CELESTIAL BLUE
OF THIS RIVER

IS SWALLOWED BY THE WATERS
OF THE COLORADO ITSELF,

WHICH RUN WITH SEDIMENT FED
IN FROM OTHER SIDE CANYONS.

WATER IS KING HERE.

EVERYTHING RELIES ON IT,

AND EVERYTHING
IS AT ITS MERCY.

ALONG ITS LENGTH,
THE COLORADO HAS MORE DAMS

THAN ANY OTHER RIVER
IN THE WORLD

TO TAP THE POWER
OF THE WATER

AS IT SURGES SOUTHWEST.

WATERFALLS SPRING
FROM ROCK FACES

AND PRODUCE
SOME OF THE GRAND CANYON'S
MANY SURPRISES.

SOME SIDE CANYONS
HAVE PERMANENT WATER COURSES,

PROVIDING SANCTUARY
FOR MANY ANIMALS.

THERE ARE RICH PICKINGS HERE
FOR WATER BEETLES

AND AMERICAN DIPPERS.

THE ROCKS SURROUNDING
THESE CREATURES

HAVE BEEN CARVED
INTO EXQUISITE SHAPES BY WATER.

( Native American singing )

THE CANYON FLOOR
IS SO DEEP

THAT THE SUN ABANDONS IT
LONG BEFORE IT LEAVES THE RIM.

WITH ITS DISAPPEARANCE,
MANY ANIMALS NOW EMERGE

TO A WORLD OF COOL GLOOM.

( coyotes howling )

MONSTERS STALK
THE CANYON FLOOR

WITH THE SAME THOUGHT IN MIND
AS THEIR PREHISTORIC
ANCESTORS--

FOOD.

JUST AS TERRIFYING
AS A HUGE DINOSAUR

BUT ON A FAR SMALLER SCALE,

A FEMALE TARANTULA
STALKS HER PREY.

HUNTER AND HUNTED,

THIS DRAMA HAS BEEN REENACTED
AND PERFECTED

OVER MILLIONS OF YEARS.

THE FINAL ACT
RARELY CHANGES.

NOTHING WILL SAVE
THIS JUNE BEETLE.

THE TARANTULA CANNOT EAT
HER FOOD IN SOLID FORM.

SO SHE INJECTS DISSOLVING
FLUIDS INTO HER PREY

AND DRINKS THE RESULTING
BEETLE BROTH.

IN THE LIGHT
OF THE FULL MOON

A PACKRAT LEAVES HIS NEST
TO FIND FOOD.

IN HIS CASE, IT'S A PLUMP
PRICKLY PEAR LEAF

FULL OF PRECIOUS LIQUID.

NOW THAT HE'S TAKEN
SOME LIQUID ON BOARD,

IT'S TIME FOR THE PACKRAT
TO FIND SOME PROTEIN.

BARK SCORPIONS LOOK
AS IF THEY'D BEEN MODELED
FROM WAX.

IN FACT THEY DO HAVE
A SPECIAL WAXY LAYER
IN THEIR EXOSKELETONS

TO LOCK IN
PRECIOUS MOISTURE.

RIGHT NOW, IT'S TIME
FOR A MOONLIT MATING DANCE

WHICH THEY CONDUCT
VERY CAREFULLY INDEED,

KEEPING WELL CLEAR
OF EACH OTHER'S DEADLY TAIL.

THIS IS NO QUICK FLING.

IT'S A SERIOUS
AND SOLEMN DANCE

WHICH MAY TAKE THEM
THROUGH TO DAWN.

THE MORNING SUNLIGHT
TAKES SOME TIME

TO REACH THE CHUCKWALLA
FAR DOWN ON THE CANYON FLOOR.

IT'S TIME TO MOVE
AND GET ON WITH THE FIRST
ESSENTIAL TASK OF THE DAY,

SUNBATHING.

WITH SEVERAL SURVIVAL TRICKS
UP HIS SLEEVE,

THE CHUCKWALLA IS AN OLD HAND
AT CANYON LIFE.

FOR ONE THING,
NATURAL U.V. BLOCKERS

MAKE HIS
LIMITED SUNBATHING SAFE

AS HE FLATTENS HIMSELF
FOR MAXIMUM EXPOSURE.

GAMBEL'S QUAILS
DON'T NORMALLY LIVE
THIS FAR NORTH,

BUT LIKE THE PLANTS
THEY RELY ON,

THEY'VE FOUND SUITABLE
LIVING CONDITIONS HERE.

THE MALE'S
TERRITORIAL DEFIANCE

IS WASTED
ON THIS CREATURE,

WHICH LOOKS JUST LIKE
A SCALED DOWN DINOSAUR.

IT'S A VENOMOUS
GILA MONSTER,

A SOUTHERNER
WHO'S COME NORTH.

LIKE ITS FELLOW LIZARDS,

IT'S WARMED UP
IN THE MORNING SUN,

AND NOW HAS FOOD
ON ITS MIND.

THE QUAIL
HAS SEEN HIS ENEMY

AND CALLS IN ALARM
TO HIS MATE

WHO IS STILL SITTING
ON EGGS.

SITTING TIGHT,
THE FEMALE PANTS IN THE HEAT.

THE LARGE LIZARD USES
ITS SENSITIVE TONGUE

TO FOLLOW THE QUAIL'S TRACKS
STRAIGHT TO THE NEST.

THE UNFORTUNATE QUAILS
WILL PROBABLY LOSE

THEIR ENTIRE CLUTCH
OF PRECIOUS EGGS.

QUAIL EGGS ARE A MAIN ITEM
ON THE MENU OF GILA MONSTERS,

WHICH UNDOUBTEDLY
HEADED NORTH IN THE WAKE
OF THE QUAILS

WHEN THEY COLONIZED
THIS DRY SOUTHWESTERN END
OF THE GRAND CANYON.

RAIN CLOUDS
CAST THEIR SHADOWS

ON ANCIENT PLANT SPECIES.

THE CANYON COVERS
SUCH A HUGE AREA

THAT IT DOESN'T
RAIN OVER ALL OF IT
AT THE SAME TIME.

EVERYTHING SOAKS UP
THE WELCOME RAINWATER.

SPRING RAINS
BRING SPRING FLOWERS
TO THIS DRY VALLEY.

TIME IS NOW
OF THE ESSENCE.

SO IF IT CAN BE CONDENSED
BY MATING AND EATING
AT THE SAME TIME,

WELL, WHY NOT?

A NEW GENERATION
OF BLISTER BEETLES

WILL JOIN THE CANYON'S
INSECT POPULATION

BEFORE SUCH FLOWERS
DISAPPEAR

IN A SHORT TIME FROM NOW.

THE RAINS MAY BE LIGHT,

BUT ALL THE DESERT PLANTS
RESPOND.

OCOTILLOS OPEN INVITING
TRUMPET-SHAPED FLOWERS.

RICH WITH SWEET NECTAR,

THE BRILLIANT FLOWERS ATTRACT
A TINY HUMMINGBIRD.

HUMMINGBIRDS FLY
TO THE GRAND CANYON
FOR THE SUMMER

FROM MUCH FURTHER SOUTH
WHERE THEY SPEND MOST
OF THE YEAR.

THERE'S ONE PLANT HERE
THAT ONLY FLOWERS ONCE

AFTER WAITING FOR AS LONG
AS 25 YEARS.

AND ONCE IT'S FLOWERED,

THE AGAVE WILL DIE.

AN AGAVE FLOWER SPIKE
IS AROUND SIX FEET TALL,

A HEIGHT IT TAKES
JUST TWO WEEKS TO REACH.

CARPENTER BEES,
HUNGRY FOR NECTAR,

WILL CARRY POLLEN
FROM THESE FLOWERS

TO FERTILIZE ANOTHER AGAVE.

DIFFERENT FORMS OF LIFE

MAKE THE MOST
OF THE RECENT RAINS.

BUT NOW THE SUN'S RAYS

THREATEN REMAINING POOLS
OF WATER.

THE HOLES
IN THE TORTURED ROCK

LOOK AS IF A GIANT DINOSAUR
HAD WALKED THROUGH

AND CONVENIENTLY LEFT
FOOTPRINTS FOR SMALL CREATURES
TO LIVE IN.

THE POTHOLES
ARE WATERY CITIES

WHICH SEETHE
WITH MICROSCOPIC LIFE.

THE RAINS
HAVE FILLED THESE HOLES,
ORIGINALLY MADE BY WATER,

AND THOUSANDS OF TINY
FAIRY SHRIMPS HAVE HATCHED.

THIS EGG-LADEN FEMALE

NEEDS TO BURY HER EGGS
AS DEEP AS SHE CAN

IN THE BOTTOM OF THE POOL
TO KEEP THEM SAFE,

BUT THE FAIRY SHRIMPS
ARE NOT ALONE.

TADPOLE SHRIMPS
ALSO LIVE HERE--

STRANGE LOOKING CREATURES

WHICH EVOLVED
LONG BEFORE THE DINOSAURS,

DRESSED SEEMINGLY
IN COATS OF ARMOR.

THE FAIRY SHRIMP
DIGS A HOLE FOR HER EGGS.

OTHER'S EGGS
HAVE BEEN FOUND

AND ARE BEING EATEN
BY HUNGRY FORAGING
TADPOLE SHRIMPS.

THE FEMALE LAYS HER EGGS
IN A LONG PACKET.

SHE'S HELPLESS LIKE THIS,

AND OPEN TO DANGER.

UNFORTUNATELY,
TADPOLE SHRIMPS

HAVE A TENDENCY TO EAT
THEIR SMALLER NEIGHBORS.

AFTER EATING
A CERTAIN NUMBER OF MEALS,

THE SHRIMP'S COAT
GETS TOO TIGHT,

SO IT GETS RID OF IT.

FOR A SHORT WHILE,
THE CHUCKWALLA'S WORLD

IS LIKE A VEGETABLE GARDEN
WHERE THERE'S PLENTY
FOR ALL TO EAT.

A GARDEN WHICH SUPPLIES FOOD
FOR HUNGRY YOUNG RAVENS

IN THEIR
CLIFFHANGER NEST.

THE PARENTS SPEND
THEIR WAKING HOURS

FERRYING A NEVER ENDING
ROUND OF MEALS.

RESTING PERHAPS
FROM ITS EARLIER MEAL,

THIS COLLARED LIZARD DOESN'T
KNOW HOW VULNERABLE IT IS.

( ravens cawing )

ONE LIZARD IS SAVED
BY A CLEFT IN THE ROCK.

BUT ANOTHER LIZARD
FALLS VICTIM

TO THE SHARP-EYED RAVEN.

IT LOOKS AS IF THE RAVEN
INTENDS KEEPING THIS MEAL
TO ITSELF.

BUT IN FACT, THE BIRD
WAS JUST REDUCING THE LIZARD

TO SUITABLE
CHICK-SIZED PIECES.

MEANWHILE,
THE OTHER ADULT

HAS SPOTTED AN ENEMY
RED-TAILED HAWK.

( Native American singing )

THE SUN BURNS MORE STRONGLY
AS SUMMER ADVANCES.

POTHOLES START TO SHRINK.

ANYTHING LEFT IN THE RAPIDLY
DISAPPEARING WATER

FACES ALMOST CERTAIN DEATH.

THE CLOCK WILL SOON STOP

FOR SPADE FOOT TADPOLES
AND TADPOLE SHRIMPS ALIKE.

BUT NEXT YEAR
A FRESH GENERATION OF SHRIMPS

WILL HATCH FROM EGGS
BURIED HERE.

THE SUN'S HEAT
HAS LITTLE IMPACT

ON THE RIVER WATER
STILL FLOWING FAR BELOW

AT THE BOTTOM
OF THE CANYON.

BUT EVEN THE MIGHTY COLORADO

CAN'T TURN
THE DRY SLOPES GREEN.

A FEW FEET UP
FROM THE WATER'S EDGE

IT'S STILL DESERT.

HOWEVER, IN OTHER PARTS
OF THE CANYON

THERE ARE HANGING GARDENS
FULL OF SURPRISES.

THE GRAND CANYON ENCOMPASSES
AN ASTONISHING NUMBER
OF MICROCLIMATES,

WITH PLACES
WHERE SUBTROPICAL

AND EVEN TROPICAL
SPECIES THRIVE

BECAUSE THE WATER
NEVER STOPS FLOWING.

MAIDENHAIR FERNS GROW
A FEW HUNDRED FEET AWAY

FROM SCORCHING DESERT.

COLUMBINES
AND MONKEY FLOWERS BLOOM

A LONG WAY
FROM THEIR USUAL HOMES.

AND EVEN TREE FROGS

TUCK THEMSELVES
AGAINST DAMP ROCKS.

BEYOND THESE SEMI-VERTICAL
DESERT OASES

THERE'S LITTLE GROWING
EXCEPT ALONG THE RIVERBANKS.

NOW THE DAMS HAVE REDUCED
ANNUAL FLOODING,

GREEN CORRIDORS HAVE GROWN
UP ALONG THE CANYON FLOOR.

TROPICAL HUMMINGBIRDS
SET UP HOME

IN EXOTIC TAMARISKS,

INTRODUCED
FROM THE FAR AWAY NILE.

THE GREEN CORRIDORS
PROVIDE MORE THAN ENOUGH FOOD,

NOT JUST FOR RAPIDLY GROWING
HUMMINGBIRD FAMILIES,

BUT FOR MANY OTHER SPECIES.

THE ARTIFICIAL CHANGES
TO THE RIVER FLOW

HAVE IN FACT GREATLY HELPED
AND INCREASED THE AMOUNT
OF WILDLIFE.

THERE'S MORE
YEAR-ROUND GRAZING

FOR SPECIES
LIKE MULE DEER.

AND PROTECTIVE COVER, TOO.

UNDER THE VEGETATION,

A FEMALE TARANTULA HAWK WASP
SEARCHES FOR A TARANTULA.

FLUSHING OUT AN ANGRY TARANTULA
IS RISKY WORK

BUT THE WASP MUST DO BATTLE
ON OPEN GROUND.

THE SPIDER FALLS
FOR THE WASP'S STRATEGY

AND COMBAT IS NOW CERTAIN.

THE SPIDER NOW RAISES
HER ABDOMEN

IN A GESTURE OF THREAT.

THIS IS NO EMPTY GESTURE.

SHE'S ARMED WITH FORMIDABLE
3/4 INCH LONG VENOMOUS FANGS.

THE WASP'S WEAPONS
ARE A LONG AND EXTREMELY
POWERFUL STING

AND HOOKED CLAWS
FOR GRAPPLING SPIDER BODIES.

NEITHER SEEMS PARTICULARLY
ANXIOUS TO DO BATTLE.

WHILE THE TARANTULA MAINTAINS
HER DEFENSIVE POSTURE,

THE WASP IS BUSY COLLECTING
VITAL TACTILE

AND CHEMICAL INFORMATION
WITH HER ANTENNAE.

IT LOOKS AS IF THE WASP
IS DOOMED.

BUT SOMEHOW SHE ESCAPES
THOSE TERRIBLE FANGS.

AND NOW SHE PARALYZES
THE TARANTULA WITH A STING

RIGHT IN THE MOST VULNERABLE
PART OF HER BODY.

STAGE ONE NOW COMPLETE,

WITH THE SPIDER HELPLESS
BUT ALIVE,

THE WASP MUST GET ON
WITH STAGE TWO.

SHE MUST GO OFF
AND FIND A HOLE

AND BURY IT.

MEANWHILE, HUNDREDS OF FEET
UP THE CANYON WALL,

THE RAVEN CHICKS
WILL SOON BE TAKING
THEIR FIRST FLYING LESSONS.

BUT UNTIL THEN,
FOOD STILL TAKES PRIORITY.

( cawing )

THE FIRST ATTEMPT
LOOKS DISASTROUS.

THE CHICK'S EFFORTS
ARE MORE LIKE ABSEILING
THAN FLYING.

WITH A CRASH-LANDING
AT THE END OF IT.

IT'S AS WELL THEIR BONES
ARE VERY SOFT AT THIS AGE.

THE PARENTS NOW HAVE
THEIR WORK CUT OUT

TO FEED YOUNGSTERS
SCATTERED ALL OVER THE PLACE.

NOW THEY'RE DOWN AS FAR
AS THEY CAN GO,

THEY'VE GOT NO CHOICE.

IF THEY WANT TO GET BACK
TO THE NEST,

THAT MEANS FLYING THERE.

IT'S STRANGE THAT THEIR FIRST
REAL FLYING SUCCESS

WILL BE UPWARDS.

NOT FAR FROM THE RAVENS,

A DESERT OCOTILLO
IS LOSING ITS LEAVES.

IN DROUGHT CONDITIONS
THIS HAPPENS NATURALLY,

BUT THIS LOSS OF LEAF
HAS ANOTHER CAUSE.

HARVESTER ANTS VALUE
THIS SOURCE OF FOOD AND WATER.

WITH SHARP JAWS
THEY SEVER THE LEAVES

AND TAKE THEM BACK
TO UNDERGROUND STOREROOMS.

WHAT AN IRRESISTIBLE LINE-UP

FOR A WELL CAMOUFLAGED
HORNED LIZARD.

THE TARANTULA HAWK WASP
HAS DUG A HOLE

WHERE SHE'LL BURY
THE LIVING SPIDER

ON WHICH HER LARVAE
WILL FEED.

NOW SHE FACES
THE MONUMENTAL TASK

OF GETTING THE SPIDER
INTO THE HOLE.

PROBABLY THE EQUIVALENT
OF A LION

DRAGGING A FULL GROWN RHINO.

( coyotes howling )

THE AIR IN THE GRAND CANYON
CAN BE SO CLEAR

THAT A RISING MOON CASTS
STRONG SHADOWS

ON ROCKS AND PLANTS.

FLOWERS OF THE SACRED
BUT POISONOUS DATURA

THROW OPEN THEIR PETALS
TO POLLINATORS.

THEIR SCENT IS SO HEADY

THAT EVEN A RINGTAIL
IS DRAWN TO THEM,

PERHAPS RECOGNIZING THAT OTHER
EDIBLE CREATURES

WILL BE ATTRACTED, TOO.

HAVING TO FIND FOOD
UNDER SUCH STRONG MOONLIGHT

IS A RISKY BUSINESS.

BUT A PACKRAT MUST HAVE
FOOD AND DRINK.

THE RAT'S RUSTLINGS
HAVE BEEN PICKED UP
BY THE HUNGRY RINGTAIL.

A NARROW SQUEAK
FOR THE PACKRAT

AND A FRUSTRATED RINGTAIL.

THE RISING SUN BRINGS
ANOTHER HOT SUMMER'S DAY

TO THE GRAND CANYON.

HEAT RADIATES FROM THE ROCK
AND CLIFF FACE

AND MOST CREATURES
HIDE THEMSELVES AWAY.

BUT EVEN IF
IT IS HIGH SUMMER,

THAT IS WHEN MALE TARANTULAS
MUST FIND MATES.

THEIR LONG MIGRATIONS
ARE FRAUGHT WITH DANGER.

THE HUGE CANYON
IS AN IMPASSABLE BARRIER

TO NEARLY ALL WILDLIFE.

BUT IT'S JUST
A SHORT FLYING DISTANCE
FROM RIM TO RIM

FOR THE RAVEN FAMILY.

NOW FULLY FLEDGED,

THE YOUNG RAVENS
HAVE OBVIOUSLY PASSED
THEIR FIRST FLYING TEST.

BUT ONE CRAFTY PARENT USES
THE LURE OF FOOD

TO GET THEM AIRBORNE AGAIN.

THE MIGRATING
TARANTULA MALE

MAY NOT HAVE
THE POWER OF FLIGHT,

BUT NEEDLE-SHARP
RETRACTABLE CLAWS

MAKE ANY VERTICAL ROCK
A PIECE OF CAKE.

ONCE HE REACHES
THE CANYON FLOOR

HE BECOMES
EVEN MORE VULNERABLE.

SUMMER MONSOON RAINS
TURN THE CANYON

INTO AN AMPHITHEATER
FOR NATURAL DRAMA
ON A GRAND SCALE.

VIOLENT THUNDERSTORMS
AND TORRENTIAL RAINS

CARRY IN THEIR WAKE
THE THREAT OF FLASH FLOODS.

AND WITHOUT EXCEPTION,
THESE PUT THE CANYON ANIMALS

AT RISK OF THEIR LIVES.

( thunder rumbling )

THE FLOODS ARE BAD ENOUGH
FOR THE ANIMALS,

BUT SOMETHING FAR, FAR WORSE
IS ON ITS WAY.

SOMETHING THAT ARRIVES
RARELY AND WITHOUT WARNING.

A TERRIFYING ENEMY
THAT SPARES NOTHING
AND GIVES NO QUARTER,

SWEEPING EVERYTHING
BEFORE IT.

THE FLASH FLOOD
WAS ONLY THE CALM
BEFORE THE REAL STORM.

NOW, WHOLE ROCK SLOPES
START TO CRUMBLE

AND SLIP INTO THE CANYON.

THOUSANDS OF TONS
OF SOIL AND ROCK

FLOW LIKE A RIVER.

GIANT BOULDERS MOVE
AS EASILY AS ROLLING MARBLES.

AND TREES ARE SNAPPED
LIKE MATCHSTICKS.

ONE BOULDER
WEIGHING 280 TONS

WAS CARRIED
TO THE RIVER LIKE THIS.

THIS IS A DEBRIS FLOW,

A PALTRY TERM
FOR THE REAL POWER

WHICH SHAPED
THE GRAND CANYON.

THESE DESTRUCTIVE
RIVERS OF ROCK

FLOW AT GREAT SPEED--

PRIMITIVE FORCES,
WHICH FOR MILLIONS OF YEARS

HAVE CHANGED THE FACE
OF THE GRAND CANYON.

DEBRIS FLOWS POUR LITERALLY
HUNDREDS OF THOUSANDS OF TONS

OF ROCK
AND SEDIMENT INTO THE RIVERS
OF THE GRAND CANYON.

THEY HAVEN'T HAPPENED
IN THE MAIN CANYON SINCE 1963,

BUT IN ALL THE SIDE CANYONS,
LIKE HAVASU CREEK,

THINGS GO ON ALMOST EXACTLY
AS THEY HAVE

FOR FIVE MILLION YEARS.

BEING ABLE TO SWIM
SAW CHUCKWALLAS THOUGH
SUCH EVENTS

AND INFLATING THEIR BELLIES

MADE PRIMITIVE
BUT EFFICIENT LIFE JACKETS.

THEIR ANCIENT SURVIVAL TRICKS

UNDOUBTEDLY MEANT
THAT GENERATIONS
OF CHUCKWALLAS

WITNESSED SCENES LIKE THIS.

THE LITTLE COLORADO'S
TURQUOISE WATERS

HAVE BEEN TRANSFORMED
BY ROCK AND SEDIMENT.

AND IN THE DAYS
BEFORE THE DAMS WHERE BUILT,

THE COLORADO ITSELF
WOULD HAVE LOOKED LIKE THIS.

IT WAS THE RICH
RED-BROWN WATER

THAT INSPIRED
ITS SPANISH NAME,
"COLORED RED."

ALMOST 400,000 TONS
OF SEDIMENT A DAY

USED TO FLOW
OUT OF THE GRAND CANYON.

SINCE THE DAMS CAME,

THAT'S DROPPED
TO 40,000 TONS.

AND MOST OF IT
COMES FROM SIDE CANYONS
LIKE THE LITTLE COLORADO,

WHERE THE WATERS SOMETIMES
LOOK LIKE LIQUID BUTTERSCOTCH.

THERE'S NOT MUCH THAT CAN
SURVIVE SUCH RADICAL CHANGES
TO RIVERS.

BUT THERE ARE SOME
ANCIENT FISH

LIKE HUMPBACK CHUBB
AND RAZOR-BACK SUCKERFISH

THAT ONCE MADE THEMSELVES
COMPLETELY HOME IN THEM.

THEY'VE NEARLY ALL GONE
FROM THE COLORADO ITSELF.

THEY CAN'T TOLERATE
ITS COLD, CLEAR WATERS
ANY LONGER,

BECAUSE OF THIS.

JUST UP RIVER
OF THE GRAND CANYON,

THIS CONCRETE GIANT IS BIGGER
THAN THE BIGGEST DINOSAUR.

THE 700-FOOT
GLEN CANYON DAM

TAPS COLORADO WATER POWER
TO DRIVE TURBINES

PRODUCING ELECTRICITY
FOR DISTANT CITIES.

THE DAMN CONTROLS
THE RIVER FLOW

AND THE MEN
THAT CONTROL THE DAM

HAVE THE POWER
TO LIGHT UP LOS ANGELES,

PHOENIX
AND LAS VEGAS.

( horns honking )

JUST THINK OF THE AMOUNT
OF RIVER POWER

GIVING THRILLS HERE.

LAS VEGAS WOULD PUT UP
A PRETTY POOR SHOW

WITHOUT THE COLORADO'S WATER.

DOWN IN THE REAL GRAND CANYON,

ABOUT 20,000 PEOPLE
EACH YEAR

GET THEIR THRILLS
RUNNING THE RAPIDS.

THE RIVER DROPS
OVER 2,000 FEET

IN ITS JOURNEY
THROUGH THE CANYON.

THIS IS THE ULTIMATE
ROLLER-COASTER RIDE

THROUGH SCENERY THAT ECLIPSES
ANY DISNEY FANTASYLAND.

YA-HOO!

THE RUNNERS OWE A LOT
OF THE SPEED AND THRILL
OF THEIR RIDES

TO THOSE IN CHARGE
OF THE DAM'S OUTPUT.

BECAUSE THE RIVER
IS ARTIFICIALLY CONTROLLED,

THE DAY COULD COME
WHEN IT'S UNRUNNABLE
IN PLACES

FROM BLOCKAGES WHICH
NATURAL FLOODS WOULD ONCE
HAVE CLEARED AWAY.

THERE USED TO BE GIGANTIC
NATURAL DAMS HERE.

OVER A MILLION YEARS AGO,
LAVA FLOWING INTO THE CANYON

BUILT ONE WALL
NEARLY THREE AND A HALF
TIMES THE HEIGHT

OF THE GLEN CANYON DAM.

NO BUTTON PUSHERS
WERE AROUND THEN

TO CONTROL THE LAKE
WHICH TOOK 22 YEARS TO FORM

BEHIND THE WALL
OF COLD LAVA,

WHICH WAS EVENTUALLY DESTROYED
BY THE RIVER.

THE IRONY OF THE ARTIFICIAL
CONTROL OF THE RIVER

IS THAT MUCH WILDLIFE
HAS DIRECTLY BENEFITED FROM IT.

LIFE IS MORE SECURE
ALONG RIVERBANKS

ONCE WASHED AWAY REGULARLY
BY FLOODS.

THE GLEN CANYON DAM
HAS BROUGHT OTHER CHANGES.

TROUT THRIVE
IN THE YEAR-ROUND COLD WATER

IT FEEDS INTO THE COLORADO.

THE GRAND CANYON
HAS BEEN TURNED INTO

ONE OF THE BEST TROUT RIVERS
IN THE WORLD.

IT'S A MECCA
FOR VARIOUS ANIMALS
THAT LIKE TROUT.

AND WHAT A SPECTACULAR PLACE
TO REEL IN FISH

THAT GROW FAT ON INSECTS
WHICH HAVE GROWN FAT ON PLANTS

THAT DO WELL IN CLEAR WATER.

IT'S A PARADOX THAT SOME NATIVE
WILDLIFE SPECIES HAVE SUFFERED
FROM THE DAMS

WHILE MANY OTHERS
HAVE BENEFITED.

IT COULD EVEN BE ARGUED
THAT THE PRESENT GRAND CANYON

IS A RARE EXAMPLE
OF NATURE'S DESIGN

ACTUALLY BEING
IMPROVED UPON.

IN OUR CENTURY,
CHUCKWALLAS HAVE SEEN US
CHANGE THEIR RIVER

AND TURN IT TO OUR PROFIT.

BUT NOW THERE ARE ATTEMPTS
TO RETURN THE RIVER'S CHARACTER

TO WHAT IT WAS
BEFORE THE DAMS.

IN APRIL, 1996,
45,000 CUBIC FEET OF WATER
A SECOND

WERE RELEASED
FROM THE GLEN CANYON DAM WALL

IN A FIRST-EVER EXPERIMENT

DESIGNED TO IMITATE
NATURAL FLOODING.

DESPITE THE ENORMOUS QUANTITY
OF WATER RELEASED,

THE SPIKE FLOW
WAS NOWHERE NEAR
PRE-DAM NATURAL PEAKS

OF OVER 200,000 CUBIC FEET
A SECOND.

THIS EXPERIMENT WAS PART
OF AN ONGOING CONTROVERSY

AS TO WHETHER THE DAMN
SHOULD BE OPERATED

TO MIMIC PRE-DAM RIVER
CONDITIONS.

THIS MIGHT NOT
EVEN BE POSSIBLE,

GIVEN THE PRESENT COMPLEX
NATURE OF THE GRAND CANYON

AND ITS NATIVE
AND INTRODUCED WILDLIFE.

HUMAN IMPACT
ON THE GRAND CANYON
THIS CENTURY

MAY BE NOTHING
TO THE NATURAL EVENTS

IN ITS FIVE MILLION
YEAR HISTORY.

IT WILL GO ON CHANGING,

JUST AS IT ALWAYS HAS.

AND THE CHANCES ARE
THAT FUTURE CHUCKWALLAS

WILL SEE THE END
OF OUR DAMS

JUST AS THEIR ANCESTORS

SAW THE END
OF THE DINOSAURS.

( end theme music playing )