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Science & Nature
Photo
The Earth
Beneath Your Feet
by Conrad J. Storad
Earth is a very special place. Our little world is the
third of eight planets that orbit a star called Sol. Earth
is home. And it’s really the only home we know.
But astronomers and planetary scientists have
another name for Earth. They call Earth a “Goldilocks
planet.” Why? Because the range of conditions that
exist on Earth are “just right” to support all kinds of
living things.
Rock layers that make up the top part of the Earth’s
crust are visible in the Grand Canyon.
Photo by Conrad J. Storad
The poles are the areas at the top and bottom of our
planet. The temperatures there are usually freezing
cold. The equator is the area that wraps around the
middle of Earth. Rain forests grow there. It is usually
quite hot and humid.
Near the top of Earth’s highest mountains, the air
is much too thin to breathe. And the pressure in the
deepest trenches beneath the oceans would squash
us flat.
Despite these extremes, most of Earth’s surface boasts
conditions that can support all kinds of living things.
To date, even at the extremes, the only place life has
been found is on the surface of our planet. The surface
is the thin layer between the atmosphere and crust.
Take a few steps outside of your home. Now look
down at your feet. You probably are standing on grass
or dirt. It could be concrete or blacktop. You also are
standing on the Earth’s crust.
Our planet’s crust is hidden from view in most
places. It might be covered by the water in rivers or
lakes or oceans. The crust hides beneath cities and
streets and parking lots. Or it might be buried under
forests or beneath fields of wheat and corn. But
there are places where you can see the Earth’s crust.
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The Zoroaster Granite at the bottom of the Grand
Canyon is almost 2 billion years old. This layer of rock
is one of the oldest parts of the Earth’s crust that a
human can actually touch.
Photo by Conrad J. Storad
:
by
Li
Science & Nature
Rocky cliffs near the seashore are part of the crust.
So are the steep walls of deep canyons, like the Grand
Canyon in Arizona.
The crust is a layer of rock that covers our entire
planet. Below your feet the crust goes down as deep as
40 miles. Under the ocean the crust is much thinner.
It might go down only three miles. Forty miles sounds
kind of thick. But it depends on your point of view.
Use your imagination. What if the entire Earth were
the size of a basketball? At that size, the Earth’s crust
would be a thin layer. It would be thinner than a single
hair on your head. The tallest mountains would be
specks almost too small to see.
What if you could slice the planet in half and look
inside? It might look like a giant peach with four
different layers. Some layers would be thin. Others
would be very thick.
Geologists are scientists who study the parts and
layers of the Earth. They study how the layers formed
and how the parts of our planet work. Some geologists
like to compare the Earth to a giant hard-boiled egg.
The Earth’s crust would be the egg’s hard outside shell.
With one difference. The crust is thick in some parts
and thin in others. The crust is thickest under the
continents. It is much thinner under the oceans.
Below the crust is a very thick layer of rock. This layer
is called the mantle. The mantle is more than 1,800
miles thick. It is kind of like the springy white part
of the giant hard-boiled egg. Deep inside Earth is
still another layer called the core. The core is like the
yellow yolk of the giant egg. The Earth’s core has two
parts. The outer part is made of super-hot melted rock.
Scientists think the outer core may be as hot as the
surface of the sun. It is more than 1,300 miles thick.
The inner part of the core is solid metal. Geologists
think it is made of iron and nickel. The inner core is
more than 1,500 miles thick.
Of course, the Earth is much bigger than a basketball.
And it is much more complex than a peach or an egg.
But you get the idea. Our planet is made of different
parts. And it’s all right beneath your feet.
Resources to learn more
about Earth’s crust:
WEBSITES:
• Geology for kids
http://www.kidsgeo.com/geology-forkids/0021-earths-crust.php
• Easy science for kids
http://easyscienceforkids.com/all-aboutearths-crust
DOCUMENTARY FILMS AND BOOKS:
• Earth Story
http://topdocumentaryfilms.com/earth-story
• Uncovering Earth’s Crust
by Conrad J. Storad
• Earth’s Changing Surface
by Conrad J. Storad
Conrad J. Storad
The award-winning author and editor of more than
50 science and nature books for children and young
adults, Conrad J. Storad expertly draws young readers
into his imaginative and entertaining “classroom”
to help them better understand and appreciate the
natural world.
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