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(SCIENCE TREK MUSIC)

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JOAN CARTAN-HANSEN, HOST:

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Icebergs are chunks of ice that

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break off glaciers.

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In the northern hemisphere, most

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icebergs break off from glaciers

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in Greenland or Alaska.

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In the southern hemisphere, most

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break off from glaciers in

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Antarctica.

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The process of ice falling off

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is called calving.

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It can make quite a splash.

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(splash) Icebergs are made of

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fresh water and float in the

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ocean.

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They eventually drift into

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warmer waters and melt.

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Icebergs can be quite small,

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less than a few feet across.

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Or they can be very large,

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sometimes the size of the island

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of Sicily.

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Only as little as one-eighth of

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an iceberg is visible above

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water.

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Most of the ice is underwater

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and that's why they are so

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dangerous.

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Ships can't see the sharp,

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jagged ice underneath the waves.

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In 1912, the unsinkable British

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ocean liner the Titanic hit an

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iceberg and, well, sunk.

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More than 15 hundred people

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drowned.

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After that, an international ice

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patrol was established to track

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icebergs and warn ships.

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For more information about

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glaciers check out the science

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trek website.

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You'll find it at Science Trek

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dot org