2. How do we determine the composition of the
Earth?
• Scientists cannot see the interior so they must
use other ways to figure it out!
• Earthquakes have many different types of waves
• These waves travel at different speeds
through solids and liquids
• Some waves don’t travel at all through liquids.
• Measuring these waves tells us what is in the
Earth’s core and where the materials change.
3.
4. Earth Layers
• The Earth is divided into four main
layers.
*Inner Core
*Outer Core
*Mantle
*Crust
5. The Earth’s Crust
• The crust is the thinnest layer on Earth
• There are two types of crust
• Oceanic crust – made mostly of the igneous rock
basalt. Found under the ocean. Relatively thin.
• Continental crust – made mostly of granite. Found
under the continents. Relatively thick.
6. Special parts of the Crust
• Lithosphere
• Crust is the upper part of the lithosphere
• Broken up into large plates
• Asthenosphere
• Upper part of mantle, below lithosphere
• 130 – 160 km thick
• Cooler part of the mantle that the
lithospheric plates slide on top of.
7.
8.
9. 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
10. 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
11.
12. 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
slid. (Solid rock that flows very slowly.)
15. The Earth’s Core
The Earth’s Core
• Composed of the inner and outer core
• Both are made of iron and nickel
16. • How do scientists know that
there is a solid inner core?
17.
18. 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
19.
20. 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
field