[MUSIC]
Joan Cartan-Hansen, Host: A
little stream like this couldn't
move much soil.
But give it enough time, and
that little stream could carve
something like this!
That's the power of erosion.
Erosion is a geological process
where soil, rocks and other
materials that make up the earth
are worn away by natural forces
like wind, water, and changes in
temperature.
Human activity can cause erosion
too.
Soil erosion can wear away the
first layer known as topsoil.
Without topsoil, crops have a
difficult time growing.
And when topsoil is washed away,
it can pollute water supplies.
One of the worst examples of
lost topsoil happened in the
American Midwest in the 1930s.
It was called the dust bowl
because more than 850 million
tons of topsoil was blown away
in dust storms.
So what can we do to protect
topsoil?
Farmers can keep their ground
covered, if possible.
If we want to eat and safeguard
the environment, we need to
protect our soil.
For more information about soil,
check out the science trek
website.
You'll find it at science trek