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(MUSIC) 
JOAN CARTAN-HANSEN, HOST:

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GEOLOGY IS THE STUDY OF OUR 
PLANET, EARTH.

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THE EARTH FORMED ABOUT FOUR 
AND A HALF BILLION YEARS AGO

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OUT OF A CLOUD OF SWIRLING GAS 
AND DUST.

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SCIENTISTS THINK THAT THE 
ANCIENT MICROBES ON EARTH MAY

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HAVE ONCE USED A MOLECULE 
OTHER THAN CHLOROPHYLL TO

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HARNESS THE SUN'S POWER.

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THAT MEANS THE ORGANISMS ON AN 
EARLY EARTH MADE THE PLANET

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LOOK PURPLE.

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THE EARTH ONCE HAD ONE GIANT 
LAND MASS CALLED A SUPER

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CONTINENT.

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THERE WERE SEVERAL OVER TIME, 
THE LAST ONE NAMED PANGAEA.

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EVENTUALLY, THE LAND BROKE UP 
AND MOVED INTO THE SHAPES WE

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HAVE TODAY.

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AND THE TECTONIC PLATES THAT 
MAKE UP THE EARTH'S LAND MASS

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STILL MOVE AT ABOUT THE SAME 
SPEED AS YOUR FINGERNAILS

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GROW.

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LOTS OF THINGS HAVE CHANGED 
THE SHAPE OF THE SURFACE OF

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THE EARTH.

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THINGS LIKE EARTHQUAKES, 
VOLCANOES, WIND, WATER AND

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WEATHER HAVE SCULPTED WHAT WE 
SEE.

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AND EVEN THOUGH THE WORD EARTH 
IS A PHRASE THAT MEANS GROUND,

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70 PERCENT OF THE EARTH'S 
SURFACE IS ACTUALLY COVERED IN

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WATER.

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FOR MORE INFORMATION ABOUT 
GEOLOGY, CHECK OUT THE SCIENCE

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TREK WEBSITE.

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YOU'LL FIND IT AT SCIENCE TREK 
DOT ORG