The longest cave in the world is the 'Mammoth Cave System' in the USA at 560,000 mtrs deep!
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The Caspian Sea is also classed as the world's largest lake.
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Australia's Great Barrier Reef is 1,250 miles long!
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An earthquake on Dec. 16, 1811 caused parts of the Mississippi River to flow backwards.
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In 1850, only 8% of the people in California were women.
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Connecticut and Rhode Island never ratified the 18th Amendment (Prohibition).
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Every year, Alaska has about 5,000 earthquakes.
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The North Atlantic gets 2.5 centimetres (1in) wider every year.
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