1. Earth’s Interior
EQ: Describe the different layers of the earth. Explain how scientist learned about these layers.

2. Probing the earth
Scientist measured the time it takes for Seismic Waves to travel through the earth

3. Earth’s 3 main layers Crust Mantle A very thin rocky layer
Continents mostly granitic rocks
Oceans (sea floor) mostly basaltic rocks
Mantle
Rocky (molten rock) below the earth surface
Makes up 80% of the earth’s volume

4. Earth’s 3 main layers Core Outer core Layer of liquid iron
Seismic velocities are lower than mantle
Creates a show zone for P and S waves
Source of earth’s magnetic field
Inner Core
Composed of solid iron

5. Five Mechanical Layers
Lithosphere
Contains all the crust and portion of upper mantle
Asthenosphere (upper mantle)
Zone of partial melting in the upper mantle low velocity zone
Facilitates movement of tectonic plates
Mesosphere (lower mantle)
Behaves like plastic (solid and flowing)
Outer Core
Inner Core

6. Internal Boundaries The Moho (Mohorovicic Discontinuity)
The boundary between the crust and the mantle
The Core-Mantle Boundary

7. Magnet and Gravity Earth as a Magnet
Earth’s magnetic field extends beyond the atmosphere into space
Caused by motions within the outer core produce electrical currents that create earths magnetic field
Earth’s Gravity
Gravity: Force that attracts a body to the center of the earth
Weight and Mass
Weight: Measure of the strength of the gravitational pull on an object.
An objects weight depends on its mass and its distance from the earths center.

8. Magnet and Gravity Weight and Mass (Cont)
Distance between earth’s surface and its center is greater at the equator than at the poles
An object at the equator is 0.3% less then its weight at the North Pole

9. Left Side Activity
Draw, Color, and Label a cross section of the Earth.
Crust
Mantle
Lithosphere
Asthenosphere
Mesosphere
Outer Core
Inner core

10. Earth’s Interior Review
Geologist have used two main types of evidence to learn about Earth’s Interior
Direct evidence from rock samples – rocks drilled from deep inside earth allow geologist to make inferences about conditions
Indirect evidence from seismic waves – seismic waves produced by earthquakes allow scientists to measure the speed in which they travel giving clues to the structure of the planet.

11. Earth’s Interior Review
Three main layers of Earth vary greatly in size, composition, temperature and pressure.
The Crust (Lithosphere)
Oceanic Crust: Mostly Basalt
Continental Crust: 4 times thicker, mostly granite
The Mantle
Upper Mantle
Lithosphere: crust and upper mantle , 100 km thick
Asthenosphere: Hotter and under increased pressure
Lower Mantle (Mesophere): Solid (plastic material extending to earth’s core
The Core (Iron and Nickel)
Outer Core: Liquid molten metal
Inner Core: dense ball of solid metal