Transcript The Earth’s Layers - Welcome to Ms. George's Science Class

The Earth’s Layers
The Earth has 4 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 hotter still and are under
enormous pressure.
Continental Crust
Crust
Oceanic Crust
• The Earth's Crust is like the skin of an apple. It is
very thin in comparison to the other layers.
• The crust is 5-100 km. thick
• There are two types of crust:
Continental Crust and Oceanic Crust
• Both continental crust and oceanic crust are
made of the elements oxygen, silicon, and
aluminum.
Crust
The temperature of the crust
varies from air temperature
at the top to 900 C. at the
bottom (hot enough to melt
rock!)
Mantle
• The mantle is the
thickest layer of the
Earth, 2900
kilometers thick.
• Very hot, dense rock
like asphalt under a
heavy weight.
• The temperature of
the mantle varies
from 900 Celsius at
the top to about
3000 Celsius near
the bottom!
The Mantle
• No one has ever visited the
mantle.
• With present technology,
we can’t drill far enough
through the crust to get to
the mantle.
• So how do scientists
“know” about the mantle?
• They observe places
where mantle rock pushes
close to the Earth’s
surface, such as where
lava pours out of active
volcanoes on the ocean
floor.
Convection Currents in the Mantle
Convection Current Animation
http://education.sdsc.edu/optiput
er/flash/convection.htm
http://www.absorblearning.com/
media/item.action?quick=12p
• Convection currents are
caused by the very hot
material at the deepest part
of the mantle rising, then
cooling, sinking again and
then heating, rising and
repeating the cycle over
and over.
• When the convection
currents flow in the mantle
they also move the crust.
The crust gets a free ride with
these currents.
• The movement of the
mantle is the reason that
the plates of the Earth
move!
The Core
• The core of the
Earth is like a ball
of very hot metals.
3000 C. to 4000 C.
• Iron & small
amounts of nickel
• The Earth’s
magnetism is
caused by the core.
• The outer core
is so hot that
the metals in it
are all in the
liquid state.
• 2000 km thick
• Liquid metals
(iron & nickel)
Outer Core
Inner Core
• Temperatures and
pressures are so
great here that the
iron and nickel
metals are squeezed
together and vibrate
in place as a solid.
Pressure
– In the core, the pressure is
45,000,000 pounds per square
inch.
– You would be squeezed into a ball
smaller than a marble if you were
able to go to the center of the
Earth!
On lined paper in your science binder,
copy these questions and answer
them in complete sentences:
1. What causes the mantle to "flow"?
2. What are the two main metals that
make up the Earth’s core?
3. How do temperatures and pressures
change as you move from the crust
toward the core?