(Lively music playing)

Two brains move through a maze, chomping as they go. The brains merge into one large brain.

A banner over the brain reads: Hungry Brain!

A voice says, HUNGRY BRAIN!

Text reads: Top on the Grand Canyon

A narrator says, HERE'S THE TOP ON THE GRAND CANYON.

(Bell ringing)

A yellow number on a blue background reads: 4

Narrator number two says, NUMBER FOUR. THE AGE OF THE GRAND CANYON IS UNKNOWN.

The steep cliffs of the Grand Canyon surround a river.

Narrator number one says, MILLIONS OF YEARS AGO, THE COLORADO RIVER USED TO FLOW IN THE SURFACE OF THE CANYON. THE WATER ERODED THE SAND FROM THE ROCK, AND DEEPENED IT, BIT BY BIT. TODAY, THE EFFECTS OF EROSION ARE OVER A KILOMETRE DEEP.

Text reads: 6 Million

Narrator number two says, SCIENTISTS USED TO THINK THIS PROCESS STARTED SIX MILLION YEARS AGO, BUT NEW RESEARCH SHOWS IT ACTUALLY STARTED 70 MILLION YEARS AGO.

Text reads: 70 Million

(Crowd oohing)

Text reads: 3

(Bell ringing)

Narrator number two says, NUMBER THREE: IT'S A POPULAR TOURIST ATTRACTION.

Narrator number one says, LAST YEAR, MORE THAN SIX MILLION TOURISTS VISITED THE GRAND CANYON.

Colour photographs show people standing on viewing platforms on top of the Canyon.

Narrator number two says, SO MANY VISITORS CAN REALLY PUT THE SQUEEZE ON SUCH A FRAGILE ECOSYSTEM.

Narrator number one says, YOU SAID IT. A LOT OF VISITORS DON'T STICK TO THE RULES, AND DAMAGE THIS UNIQUE ENVIRONMENT.

Narrator number two says, IF WE EVER GO THERE, WE'LL RESPECT THE RULES.

Text reads: 2

Narrator number one says, NUMBER TWO: THERE'S A VILLAGE AT THE BOTTOM OF THE GRAND CANYON.

Narrator number two says, THERE SURE IS! A TINY RESERVATION, WHERE 206 PEOPLE FROM THE HAVASUPAI TRIBE LIVE. THE NAME MEANS "THE PEOPLE OF THE BLUE-GREEN WATERS," AFTER THE SPECTACULAR TURQUOISE WATERFALL THAT FLOWS ON THEIR LAND.

A photograph shows the tall, narrow waterfall.

Narrator number one says, IT TAKES HOURS TO WALK THERE, BECAUSE THE RESERVATION ISN'T ACCESSIBLE BY ANY ROADS. WANT A FOOD PARCEL? BETTER HIRE A MULE.

(Doorbell ringing)

Narrator number two says, I WAS WONDERING WHY MY PIZZA DELIVERY WAS TAKING SO LONG.

Text reads: 1

Narrator number one says, NUMBER ONE: THE COLOUR OF THE COLORADO RIVER HAS CHANGED. IN THE OLDEN DAYS, THE COLORADO RIVER WAS RED-BROWN. WHY? BECAUSE IT WAS PACKED WITH FINE PARTICLES OF EARTH.

Narrator number two says, IN SPANISH, COLORADO MEANS RED. TODAY, THE WATER IS BLUE-TURQUOISE. HOW COME? IN THE 1960S, THE GLEN CANYON DAM WAS BUILT UPSTREAM ON THE RIVER ABOVE THE GRAND CANYON. IT FILTERS OUT SMALL ROCK PARTICLES THAT MADE THE WATER REDDISH-BROWN. NOW THE WATER'S BLUE-GREEN, THANKS TO LOTS OF MICROSCOPIC ALGAE.

Green water flows in a wide pool.

Narrator number one says, THANKS TO ALGAE, THE CANYON IS JUST GORGEOUS. GET IT?

(Music playing)

End credits read:
Narration: Helen Moorhouse, Iain O’Connor
Trio Orange
AQPM
Copyright 2019