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JOAN CARTAN-HANSEN, HOST: LOTS 
OF DIFFERENT FORCES HELPED

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SHAPE ALL THE PLANETS IN OUR 
SOLAR SYSTEM, INCLUDING THE

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EARTH.

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FIND OUT MORE ON SCIENCE TREK.

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(MUSIC) 
YEARS OLD.

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IT HAS AN INNER CORE OF SOLID 
METAL SURROUNDED BY A LAYER OF

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LIQUID METAL.

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THIS IS THE MANTLE.

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A MULTILAYERED COLLECTION OF 
HOT, HEAVY ROCK.

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IT'S ABOUT 1800 MILES THICK.

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AND ON TOP IS THE ROCKY CRUST.

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THAT'S THE PART OF THE EARTH WE 
SEE.

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THE PART WE LIVE ON.

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GEOLOGISTS BELIEVE THE EARTH WAS 
SHAPED BY LOTS OF DIFFERENT

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FORCES OVER PERIODS OF TIME.

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AND BY STUDYING THE LAYERS OF 
ROCK AND DIRT, AND EXPLORING THE

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CONTOURS OF THE LAND, YOU TOO 
CAN LEARN HOW THOSE FORCES SHAPE

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THE EARTH.

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THE SURFACE OF THE EARTH IS MADE 
UP OF BITS OF LAND KNOWN AS

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SLATE.

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THESE SLATES -- PLATES ARE 
MOVING, SLIDING PAST ONE

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ANOTHER, FOLDING UNDERNEATH OR 
BUTTING UP AGAINST EACH OTHER.

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THE PRESSURE BETWEEN TWO PLATES 
BUILDS UP TO MORE THAN THE ROCKS

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AROUND THEM CAN STAND, THE 
PLATES CRACK AND THE ENERGY IS

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RELEASED IN WHAT WE KNOW AS AN 
EARTHQUAKE.

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>> YOU CAN SEE WHY AN EARTHQUAKE 
CAN CAUSE A LOT OF DAMAGE.

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PUT TWO BLOCKS TOGETHER AND 
COVER THEM WITH A LAYER OF SAND.

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PUT A FEW BUILDINGS AND ANIMALS 
ON TOP.

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AND THEN MOVE ONE OF THE BLOCKS.

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AND THAT'S WHEN AN EARTHQUAKE 
LOOKS LIKE.

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>> EARTHQUAKES ARE MOST COMMON 
WHERE THE PLATES MEET.

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THAT'S KNOWN AS A FAULT LINE.

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IDAHO IS NUMBER SIX ON THE LIST 
OF STATES WITH THE MOST

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EARTHQUAKES.

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A VOLCANO IS BASICALLY A HOLE IN 
THE EARTH'S CRUST WHERE LAVA

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COMES OUT.

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LAVA IS HOT, MOLTEN ROCK.

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>> LAVA HAS VISCOSITY.

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SOME LAVA, LIKE THIS TOOTHPASTE, 
COMES OUT THICK.

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>> OTHER LAVA LIKE THIS, COMES 
OUT LIKE LIQUID.

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>> EVENTUALLY THE LAVA COOLS 
INTO ROCK.

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>> ANCIENT VOLCANOS CREATED THE 
TWISTED LANDSCAPE YOU SEE AT

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CRATERS OF THE MOON NATIONAL 
MONUMENT N SOME PARTS OF IDAHO

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THE MOUNTAINS WERE FORMED WHEN 
MAGMA, OR HOT LAVA, STILL

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UNDERGROUND, PUSHED UPWARD BUT 
DIDN'T BREAK THE SURFACE.

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THAT'S CALLED A BATHOLITH.

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THESE MOUNTAINS ARE PART OF THE 
IDAHO BATHOLITH.

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A LITTLE BIT OF WATER CAN 
COMPLETELY CHANGE A LANDSCAPE.

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OVER TIME, MOVING WATER EATS 
AWAY AT ROCK.

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THE THOUSANDS OF YEARS LATER, 
WHAT WAS A PLAIN CAN BECOME A

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VALLEY.

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A FLOOD CAN CHANGE THE 
LANDSCAPE.

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15,000 YEARS AGO, THE BONNEVILLE 
FLOOD SCOURED OUT THE SNAKE

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RIVER PLAIN, CARVING OUT THE 
CANYONS AT TWIN FALLS.

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AND NOT ALL FLOODS ARE CAUSED BY 
NATURE.

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WHEN THE TETON DAM BROKE IN 
1976, A WALL OF WATER ALMOST

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WIPED OUT MANY SMALL TOWNS, LUG 
MUCH OF REXBURG.

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>> GENTLE FLOW OF WATER 
DOESN'T HAVE MUCH ENERGY.

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BUT A FLOOD HAS LOTS OF ENERGY.

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SO THE AMOUNT OF DAMAGE TO THE 
LAND DEPENDS UPON HOW MUCH GEO

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FORCE IS INVOLVED.

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>> GLACIERS ARE RIVERS OF ICE 
THAT CARVER THEIR WAY THROUGH

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THE LAND.

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THEY GROW AND PUSH THEIR WAY 
THROUGH, CREATING U-SHAPED

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VALLEY WAS A FLAT BOTTOM AND 
HIGH SIDES.

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EVEN WATER IN THE FORM OF RAIN 
CAN RESHAPE THE EARTH.

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TOO MUCH RAIN ALL AT ONCE CAN 
CAUSE LANDSLIDES.

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AND EVEN GENTLE RAIN AND SNOW 
OVER TIMING WEAR AWAY THE TOP

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PART OF THE EARTH, SHOWING THE 
HARDER ROCK BELOW.

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FREEZING AND THAWING CAN ALSO 
CRACK ROCKS OPEN, MAKING IT

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EASIER FOR WATER TO EAT AWAY AT 
THE SURFACE.

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EROSION, ESPECIALLY OVER TIME, 
CAN SCULPT THE LAND.

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WATER, IN ALL ITS DIFFERENT 
FORMS, IS ONE OF THE MAJOR

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FORCES THAT SHAPE THE EARTH.

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WHAT FORCES CARVER THE EARTH 
WHERE YOU LIVE?

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IF YOU WANT TO LEARN MORE 
ABOUT GEOLOGY, CHECK OUT THE

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SCIENCE TREK WEBSITE.

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YOU'LL FIND IT AT SCIENCE TREK 
DOT ORG.

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(MUSIC)

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NARRATOR: PRESENTATION OF 
SCIENCE TREK ON IDAHO PUBLIC

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TELEVISION IS MADE POSSIBLE 
THROUGH THE GENEROUS SUPPORT

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OF THE LAURA MOORE CUNNINGHAM 
FOUNDATION, COMMITTED TO

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FULFILLING THE MOORE AND 
BETTIS FAMILY LEGACY OF

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BUILDING THE GREAT STATE OF 
IDAHO; BY THE IDAHO NATIONAL

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LABORATORY, MENTORING TALENT 
AND FINDING SOLUTIONS FOR

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ENERGY AND SECURITY 
CHALLENGES, BY THE FRIENDS OF

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IDAHO PUBLIC TELEVISION AND BY 
THE CORPORATION FOR PUBLIC