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[MUSIC]

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Joan Cartan-Hansen, Host: A 
little stream like this couldn't

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move much soil.

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But give it enough time, and 
that little stream could carve

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something like this!

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That's the power of erosion.

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Erosion is a geological process 
where soil, rocks and other

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materials that make up the earth 
are worn away by natural forces

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like wind, water, and changes in 
temperature.

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Human activity can cause erosion 
too.

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Soil erosion can wear away the 
first layer known as topsoil.

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Without topsoil, crops have a 
difficult time growing.

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And when topsoil is washed away, 
it can pollute water supplies.

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One of the worst examples of 
lost topsoil happened in the

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American Midwest in the 1930s.

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It was called the dust bowl 
because more than 850 million

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tons of topsoil was blown away 
in dust storms.

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So what can we do to protect 
topsoil?

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Farmers can keep their ground 
covered, if possible.

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If we want to eat and safeguard 
the environment, we need to

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protect our soil.

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For more information about soil, 
check out the science trek

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website.

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You'll find it at science trek