- What does the inside of the Earth look like?
- Determining 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 solids
- Measuring these waves tells us what is in the Earth’s core and where the materials change.
- The Earth is divided into four main layers.
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.
Special parts of the Crust
- Crust is the upper part of the lithosphere
- Broken up into large plates
- Upper part of mantle, below lithosphere
- Cooler part of the mantle that the lithospheric plates slide on top of.
The Earth’s Mantle
- Located directly above the outer core
- 80% of the Earth’s volume & 68% of Earth’s mass
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
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.)
The Earth’s Core
- Composed of the inner and outer core
- Both are made of iron and nickel
- How do scientists know that there is a solid inner core?
The Earth’s Outer Core
- Temperature ranges from 2200 C – 5000 C near inner core
- Molten (liquid) iron and nickel
The Earth’s Inner Core
- Temperature reaches 5000 C
- 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
- The inner core and outer cores do not turn at the same speed as the rest of the earth.
- Causes a generator effect which produces a magnetic field.
- It protects us from some of the sun’s harmful radiation.
What do you know about these layers?