2. Earth Layers
• The Earth is divided into four main
3. The Earth’s Crust
• The crust is the thinnest layer on Earth, 5 km to 100 km
• There are two types of crust
• Oceanic crust – made mostly of the igneous rock
basalt. Found under the ocean. Relatively thin,
5 km to 7 km. Contains more iron than the
Continental crust, therefore is more dense.
• Continental crust – made mostly of granite.
Found under the continents. Relatively thick, up
to 100 km.
4. Special parts of the Crust
• Crust is the upper part of the lithosphere.
• Broken up into large plates.
• The uppermost part of the mantle is also
part of the Lithosphere
• Upper part of mantle, below lithosphere
• 130 – 160 km thick
• Cooler part of the mantle that the
lithosphere plates slide on top of.
5. The Earth’s Mantle
• Located directly above the outer core
• Starts below the crust
• Is the largest layer
• 80% of the Earth’s volume & 68% of Earth’s mass
6. The Earth’s Mantle
• Composed of more iron than the crust.
• Density, pressure, and temperature all increase
the deeper you go in the mantle
• Temperature ranges from 870 C – 2200 C
7. Special layers of the mantle
• Lithosphere – crust plus the upper, solid
part of the mantle. Forms plates.
• Asthenosphere – just under the
lithosphere. Slow moving “Silly putty”
layer on which the lithospheric plates
slide. (Solid rock that flows very
8. The Earth’s Core
The Earth’s Core
• Composed of the inner and outer core
• Both are made of iron and nickel
9. The Earth’s Outer Core
The Outer Core - Liquid
• Surrounds the inner core
• Temperature ranges from 2200 C – 5000 C
near inner core
• Molten (liquid) iron and nickel
10. The Earth’s Inner Core
The Inner Core - Solid
• Temperature reaches 5000 C
• Solid iron and nickel
• Usually both would be liquid but are solid in the
core because of the incredible pressure
• The solid core is the source of Earth’s magnetic
• The inner core and outer cores do not
turn at the same speed as the rest of
• Causes a generator effect which
produces a magnetic field.
• It protects us from some of the sun’s
12. • What does the inside of the
Earth look like?
• How do scientists know that
there is a solid inner core?
13. Determining the composition of the Earth
• Scientists cannot see the interior of the planet,
or drill to the core, so they use seismic waves to
determine the composition of the layers.
• Seismic waves: are vibrations that are produced
when an earthquake happens.
• Seismic waves travel at different speed
depending on the composition and density of
material. Measuring these waves tells us what is
in the Earth’s layers, and how the materials