(MUSIC)
JOAN CARTAN-HANSEN, HOST:

GEOLOGY IS THE STUDY OF OUR
PLANET, EARTH.

THE EARTH FORMED ABOUT FOUR
AND A HALF BILLION YEARS AGO

OUT OF A CLOUD OF SWIRLING GAS
AND DUST.

SCIENTISTS THINK THAT THE
ANCIENT MICROBES ON EARTH MAY

HAVE ONCE USED A MOLECULE
OTHER THAN CHLOROPHYLL TO

HARNESS THE SUN'S POWER.

THAT MEANS THE ORGANISMS ON AN
EARLY EARTH MADE THE PLANET

LOOK PURPLE.

THE EARTH ONCE HAD ONE GIANT
LAND MASS CALLED A SUPER

CONTINENT.

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

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

HAVE TODAY.

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

STILL MOVE AT ABOUT THE SAME
SPEED AS YOUR FINGERNAILS

GROW.

LOTS OF THINGS HAVE CHANGED
THE SHAPE OF THE SURFACE OF

THE EARTH.

THINGS LIKE EARTHQUAKES,
VOLCANOES, WIND, WATER AND

WEATHER HAVE SCULPTED WHAT WE
SEE.

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

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

WATER.

FOR MORE INFORMATION ABOUT
GEOLOGY, CHECK OUT THE SCIENCE

TREK WEBSITE.

YOU'LL FIND IT AT SCIENCE TREK
DOT ORG