Earth’s Layers
S6E5.a. Compare and contrast the
Earth’s crust, mantle, and core including
temperature, density, and composition.
We Have 2 ways of Dividing
Earth’s Layers:
Earth is divided into 3
compositional layers:
1. Crust
2. Mantle
3. Core
CRUST:
• Location: outermost layer
• Temperature: 0°C to 1,000°C
• Thickness: 5km to 100 km
• Composition:
• Oxygen
• Silicon
• Aluminum
2 TYPES OF CRUST:
• Oceanic crust is
very thin & dense.
• Continental crust
is thick but less
dense.
•
•
•
•
MANTLE:
Location: below the crust.
Temperature: 1,000°C to 3,700°C
Thickness: 2,900 km
Composition:
• Contains most of Earth’s mass
• Solid and molten rock
CORE:
• Location: Earth’s center
• Temperature: 3,700°C - 7,000°C
• Thickness: 3,500 km
• Composition: mostly iron, some
nickel
• Divided into 2 layers:
• Outer Core
• Inner Core
Earth is divided into 5
physical layers:
1. Lithosphere
2. Asthenosphere
3. Mesosphere
4. Outer Core
5. Inner Core
LITHOSPHERE:
• This is the “crunchy” layer of the
Earth.
• Location: crust and upper mantle
• Thickness: 15-300 kilometers
• Lithosphere = tectonic plates
ASTHENOSPHERE:
• Location: the middle mantle, below
the lithosphere
• Soft – can bend like plastic
• Lithosphere floats on this layer (like
jello)
• Thickness: 250 km
MESOSPHERE:
•Location: the strong, lower part of
the mantle
•Thickness: 2,550 kilometers
Outer Core:
• Composition: liquid iron (with some
nickel)
• Thickness: 2,300 km
Inner Core:
•Composition: solid iron and a little
nickel.
•Thickness: 1,220 km thick.
•Solid because of increased
pressure.
Lithosphere
Asthenosphere
CRUST
MANTLE
OUTER CORE
INNER CORE
Mesosphere
Density, Pressure, and Temperature
• Moving towards the center of the
earth:
•Density increases
•Pressure increases
•Temperature increases
How do we know there are
layers of the earth?
•Earthquakes emit different
kinds of seismic waves that can
travel through different
substances and at different
speeds
•Scientists used these waves
to determine the layers based
on the speed and movement of
the layers!
The MOHO
•The Moho is the boundary
where the crust meets the
mantle
•It was discovered in 1909 by
Andrija Mohorovicic
•It was discovered because at
this point density changes and
seismic waves change direction
The MOHO
Why does Earth have a
magnetic field?
Why does Earth have a
magnetic field?
•Earth’s magnetic field is a result of
the movement of iron in the Earth’s
liquid inner core.
In Review:
1.What are the 3 main layers of the Earth?
Crust, Mantle, Core
2.Which layer is the least dense?
Crust
3.Which core layer is solid iron and nickel?
Inner core
4.What is the name given to the “crunchy” layer of
the crust and uppermost part of the mantle?
Lithosphere
5. The motion in this layer is the reason Earth has
a magnetic field.
Outer core