JOAN CARTAN-HANSEN, HOST: LOTS
OF DIFFERENT FORCES HELPED
SHAPE ALL THE PLANETS IN OUR
SOLAR SYSTEM, INCLUDING THE
EARTH.
FIND OUT MORE ON SCIENCE TREK.
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YEARS OLD.
IT HAS AN INNER CORE OF SOLID
METAL SURROUNDED BY A LAYER OF
LIQUID METAL.
THIS IS THE MANTLE.
A MULTILAYERED COLLECTION OF
HOT, HEAVY ROCK.
IT'S ABOUT 1800 MILES THICK.
AND ON TOP IS THE ROCKY CRUST.
THAT'S THE PART OF THE EARTH WE
SEE.
THE PART WE LIVE ON.
GEOLOGISTS BELIEVE THE EARTH WAS
SHAPED BY LOTS OF DIFFERENT
FORCES OVER PERIODS OF TIME.
AND BY STUDYING THE LAYERS OF
ROCK AND DIRT, AND EXPLORING THE
CONTOURS OF THE LAND, YOU TOO
CAN LEARN HOW THOSE FORCES SHAPE
THE EARTH.
THE SURFACE OF THE EARTH IS MADE
UP OF BITS OF LAND KNOWN AS
SLATE.
THESE SLATES -- PLATES ARE
MOVING, SLIDING PAST ONE
ANOTHER, FOLDING UNDERNEATH OR
BUTTING UP AGAINST EACH OTHER.
THE PRESSURE BETWEEN TWO PLATES
BUILDS UP TO MORE THAN THE ROCKS
AROUND THEM CAN STAND, THE
PLATES CRACK AND THE ENERGY IS
RELEASED IN WHAT WE KNOW AS AN
EARTHQUAKE.
>> YOU CAN SEE WHY AN EARTHQUAKE
CAN CAUSE A LOT OF DAMAGE.
PUT TWO BLOCKS TOGETHER AND
COVER THEM WITH A LAYER OF SAND.
PUT A FEW BUILDINGS AND ANIMALS
ON TOP.
AND THEN MOVE ONE OF THE BLOCKS.
AND THAT'S WHEN AN EARTHQUAKE
LOOKS LIKE.
>> EARTHQUAKES ARE MOST COMMON
WHERE THE PLATES MEET.
THAT'S KNOWN AS A FAULT LINE.
IDAHO IS NUMBER SIX ON THE LIST
OF STATES WITH THE MOST
EARTHQUAKES.
A VOLCANO IS BASICALLY A HOLE IN
THE EARTH'S CRUST WHERE LAVA
COMES OUT.
LAVA IS HOT, MOLTEN ROCK.
>> LAVA HAS VISCOSITY.
SOME LAVA, LIKE THIS TOOTHPASTE,
COMES OUT THICK.
>> OTHER LAVA LIKE THIS, COMES
OUT LIKE LIQUID.
>> EVENTUALLY THE LAVA COOLS
INTO ROCK.
>> ANCIENT VOLCANOS CREATED THE
TWISTED LANDSCAPE YOU SEE AT
CRATERS OF THE MOON NATIONAL
MONUMENT N SOME PARTS OF IDAHO
THE MOUNTAINS WERE FORMED WHEN
MAGMA, OR HOT LAVA, STILL
UNDERGROUND, PUSHED UPWARD BUT
DIDN'T BREAK THE SURFACE.
THAT'S CALLED A BATHOLITH.
THESE MOUNTAINS ARE PART OF THE
IDAHO BATHOLITH.
A LITTLE BIT OF WATER CAN
COMPLETELY CHANGE A LANDSCAPE.
OVER TIME, MOVING WATER EATS
AWAY AT ROCK.
THE THOUSANDS OF YEARS LATER,
WHAT WAS A PLAIN CAN BECOME A
VALLEY.
A FLOOD CAN CHANGE THE
LANDSCAPE.
15,000 YEARS AGO, THE BONNEVILLE
FLOOD SCOURED OUT THE SNAKE
RIVER PLAIN, CARVING OUT THE
CANYONS AT TWIN FALLS.
AND NOT ALL FLOODS ARE CAUSED BY
NATURE.
WHEN THE TETON DAM BROKE IN
1976, A WALL OF WATER ALMOST
WIPED OUT MANY SMALL TOWNS, LUG
MUCH OF REXBURG.
>> GENTLE FLOW OF WATER
DOESN'T HAVE MUCH ENERGY.
BUT A FLOOD HAS LOTS OF ENERGY.
SO THE AMOUNT OF DAMAGE TO THE
LAND DEPENDS UPON HOW MUCH GEO
FORCE IS INVOLVED.
>> GLACIERS ARE RIVERS OF ICE
THAT CARVER THEIR WAY THROUGH
THE LAND.
THEY GROW AND PUSH THEIR WAY
THROUGH, CREATING U-SHAPED
VALLEY WAS A FLAT BOTTOM AND
HIGH SIDES.
EVEN WATER IN THE FORM OF RAIN
CAN RESHAPE THE EARTH.
TOO MUCH RAIN ALL AT ONCE CAN
CAUSE LANDSLIDES.
AND EVEN GENTLE RAIN AND SNOW
OVER TIMING WEAR AWAY THE TOP
PART OF THE EARTH, SHOWING THE
HARDER ROCK BELOW.
FREEZING AND THAWING CAN ALSO
CRACK ROCKS OPEN, MAKING IT
EASIER FOR WATER TO EAT AWAY AT
THE SURFACE.
EROSION, ESPECIALLY OVER TIME,
CAN SCULPT THE LAND.
WATER, IN ALL ITS DIFFERENT
FORMS, IS ONE OF THE MAJOR
FORCES THAT SHAPE THE EARTH.
WHAT FORCES CARVER THE EARTH
WHERE YOU LIVE?
IF YOU WANT TO LEARN MORE
ABOUT GEOLOGY, CHECK OUT THE
SCIENCE TREK WEBSITE.
YOU'LL FIND IT AT SCIENCE TREK
DOT ORG.
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