The longest cave in the world is the 'Mammoth Cave System' in the USA at 560,000 mtrs deep!
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The Niagara Falls moves upstream at an average rate of about 295ft a century!
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An earthquake on Dec. 16, 1811 caused parts of the Mississippi River to flow backwards.
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The Amazon rainforest produces more than 20% the world's oxygen supply.
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A waterfall known as The Devil's Kettle empties water into a hole and nobody knows where it ends up!
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Venice Island was built on a foundation of tree trunks. 1200 years later, those same trunks still support almost all of central Venice.
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