Work Book Quiz
1. The outer most compositional layer of the
Earth is the ________. Page 390
2. The _____________core is the liquid layer of
the Earth’s core. Page 392
3. Define plate tectonics: page 399
4. About 200-300 million years ago the continents
were joined in a single large land mass called
___________. Page 399
5. Name 5 of the tectonic plates. Page 403
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Title Your Journal…
Layers of the Earth Notes
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What evidence supports the idea that
Earth has layers?
The behavior of seismic waves generated by
earthquakes give scientists some of the best
evidence about the structure of Earth.
(a) If Earth were uniform (homogeneous)
throughout, seismic waves would radiate
from the site of an earthquake in straight
lines.
(b) If the density, or rigidity, of Earth
increased evenly with depth, seismic wave
velocity would increase with depth, and the
waves would bend smoothly upward toward
the surface.
(c) If Earth were layered inside, some seismic
waves would be reflected at the boundaries
between layers while others were bent.
Seismic evidence shows that Earth is layered.
The Four Basic Layers
The Earth is composed of
four different layers. The
crust is the layer that you
live on, and it is the most
widely studied and
understood. The mantle
is much hotter and has
the ability to flow. The
outer core and inner core
are even hotter with
pressures so great you
would be squeezed into a
ball smaller than a
marble if you were able
to go to the center of the
Earth!
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The Crust
The Earth's Crust is like
the skin of an apple. It
is very thin in
comparison to the
other three layers. The
crust is only about 3-5
miles thick under the
oceans (oceanic crust)
and about 25 miles
thick under the
continents
(continental crust).
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Write this down
Layers of the Earth Notes
I. Layers of the Earth
A. Crust- very thin uppermost layer of
the Earth. (Where we live)
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The Crust
The crust is composed of two rocks. The continental
crust is mostly granite. The oceanic crust is basalt. Basalt
is much denser than the granite. Because of this the less
dense continents ride on the denser oceanic plates.
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The Lithospheric Plates
The crust of the Earth is broken into many pieces called
plates. The plates "float" on the soft, semi-rigid
asthenosphere. Remember this- we will learn about this
later…
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The Lithosphere
The crust and the upper layer of the mantle
together make up a zone of rigid, brittle rock
called the Lithosphere.
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Write this down
Layers of the Earth Notes
I. Layers of the Earth
A. Crust- very thin uppermost layer
of the Earth. (Where we live)
B. Lithosphere- part of the crust and
upper mantle that is rigid brittle
rock.
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The Mantle
The Mantle is the
largest layer of the Earth.
The middle mantle is
composed of very hot
dense rock that flows like
asphalt under a heavy
weight. The movement of
the middle mantle
(asthenosphere) is the
reason that the crustal
plates of the Earth move.
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Write this down
Layers of the Earth Notes
I. Layers of the Earth
A. Crust- very thin uppermost layer of
the Earth. (Where we live)
B. Lithosphere- part of the crust and
upper mantle that is rigid brittle rock.
C. Mantle- the largest layer of Earth. It is
divided into three sections called
Lithosphere, Asthenosphere, and
Mantle
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The Asthenosphere
The
asthenosphere is
the semi-solid
or semi-rigid
part of the
middle mantle
that flows like
hot asphalt
under a heavy
weight.
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A. Crust- very thin uppermost layer of
the Earth. (Where we live)
B. Lithosphere- part of the crust and
upper mantle that is rigid brittle rock.
C. Mantle- the largest layer of Earth. It is
divided into three sections called
Lithosphere, Asthenosphere, and
Mantle
D. Asthenosphere- the middle of the
mantle. This is where CONVECTION
happens.
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Convection Currents
The middle mantle "flows"
because of convection
currents. Convection
currents are caused by the
very hot material at the
deepest part of the mantle
rising, then cooling and
sinking again --repeating
this cycle over and over.
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Convection Currents
The next time you heat anything
like soup or water in a pan you
can watch the convection
currents move in the liquid.
When the convection currents
flow in the asthenosphere
they also move the crust. The
crust gets a free ride with these
currents, like the cork in this
illustration.
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B. Lithosphere- part of the crust and
upper mantle. Rigid brittle rock.
C. Mantle- the largest layer of Earth.
It is divided into three sections
called Lithosphere, Asthenosphere,
and Mantle
D. Asthenosphere- the middle of the
mantle. This is where CONVECTION
happens.
1. Convection Currents flow in the
Asthenosphere causing this layer to
have semi-solid properties.
2. Plasticity- is how we describe this
semi-solid layer.
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The Outer Core
The core of the Earth
is like a ball of very
hot metals. The
outer core is so
hot that the metals
in it are all in the
liquid state. The
outer core is
composed of the
melted metals of
nickel and iron.
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D. Asthenosphere- the middle of the
mantle. This is where
CONVECTION happens.
1. Convection Currents flow in the
Asthenosphere causing this layer to
have semi-solid properties.
2. Plasticity- is how we describe this
semi-solid layer.
E. Outer Core- The liquid layer that
surrounds the inner core.
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The Inner Core
The inner core of the
Earth has
temperatures and
pressures so great that
the metals are
squeezed together
and are not able to
move about like a
liquid, but are forced
to vibrate in place like
a solid.
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E. Outer Core- The liquid layer that
surrounds the inner core.
F. Inner Core- The very center of the
Earth. This layer is very hot and
has pressure pushing on it to
make it stay in solid form.
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How HOT is it?
II. Temperatures of Inner Layers
A. The temperature increases as
you get closer to the inner
core. The inner core is said to
be as hot as the Sun’s surface.
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The End
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