Download The four layers of the Earth

Hi, I’m
Molten!
Can We
Really Dig to
China?
Main Menu
• The Earth’s Crust
• The Earth’s Mantle
• The Earth’s Core
• Questions
• Dig Deeper With These Links
What We Will Learn
The four layers of the Earth
• The crust
• The mantle
• The outer core
• The inner core
The Earth’s 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).
• The Earth's surface is
composed mostly of water,
basalt, and granite. Oceans
cover about 70% of Earth's
surface.
The Crust
•
•
The Earth’s crust is not a solid
shell; it is broken up into huge,
thick plates that drift atop the soft,
underlying mantle.
Hey, did
those
Continents
fit
together at
one time?
CONTINETAL DRIFT
The plates are made of rock and
drift all over the globe; they move
both horizontally (sideways) and
vertically (up and down).
Click Main Menu
The Earth’s Mantle
• The mantle is made up of rock materials and is sandwiched
between the core and the crust.
• It consists of mainly solid rocks, but the upper mantle (closer
to the crust) is actually a layer of semi-liquid molten rock
called magma. This magma flows slowly underneath the crust
like plastic (think of silly putty).
• The mantle makes up most of our Earth!
Magma flows in
upper part of
mantle. This
causes plates to
move (plate
tectonics).
Convection
• Scientists believe convection currents are what cause earth’s
plates to move.
• A convection current is caused by differences in temperature.
• When a pot of water starts to boil, the water is hotter near the
bottom, close to where the heat source is located. Hotter water
is less dense, and so it rises to the top. The cooler water on top
sinks to the bottom. This is a kind of convection current.
Convection in the Mantle
• The same type of current moves
magma in the mantle of the Earth.
• This is a continuous circular
motion!
The Earth’s Outer Core
• The third layer of the earth is underneath the mantle, known
as the liquid outer core.
• It is made mostly of the metal iron.
• The heat is so intense that the metals are molten, and the
layer flows very slowly, generating energy that produces the
magnetic field of the earth.
Earth’s Inner Core
The temperature of the inner core is hotter than
the Sun's surface!
Therefore, the intense heat from the inner core
causes material in the molten outer core and
mantle to move around.
Unlike the outer core, the inner core is solid!
Click Main Menu
What Have We Learned?
• The Earth’s crust is pretty thin and is where we live.
• The Earth’s mantle is the largest part of our Earth.
• The upper part of the mantle moves slowly (kind of like
squeezing silly putty) because of magma.
• Convection is the cycle of heat rising, falling as it
cools, and then heating and rising again.
• We live on plates that are constantly moving!
• The outer core is liquid, and it produces our magnetic
field.
• The inner core is solid and is hotter than the sun.
Time to Show Off!
So, Can we dig
to China?
No…it
be too
You ar
smart!
1.
Which layer makes up most of our Earth?
2.
Which part of the Earth is hotter than the sun?
3.
What is the source of our magnetic field?
4.
Does heat rise or sink? What happens after it cools again?
5.
What is the thinnest layer of the Earth?
Click Main Menu
Answers
1.
Which layer makes up most of our Earth? mantle
2.
Which part of the Earth is hotter than the sun? inner core
3.
What is the source of our magnetic field? Because the outer
core contains iron, when it flows it generates a magnetic
field.
4.
During convection does heat rise or sink? What happens
after it cools again? Heat rises and as it cools it sinks back
down where it is heated again causing the cycle to repeat.
5.
What is the thinnest layer of the Earth? crust
Click Main Menu
Dig Deeper With These Links
• Inside the Earth - label the Earth’s structures.
• Structure of the Earth - features a globe with a
removable section.
• Science Odyssey: You Try It: Plate Tectonics - A
hands-on exercise about plate tectonics and
earthquakes from PBS. (requires Shockwave plugin)
Click Main Menu