1. Earth’s Structure

2. Earth has three main layers.
Crust
Mantle
Core
Layers are different because of their chemical composition

3. Crust We live on top of here. Thinnest layer: <1% of Earth’s mass
Continental and oceanic crusts
Minerals and rocks found here

4. Mantle Under the crust Makes up most of Earth’s mass: about 67%
Denser than the crust
Sometimes mantle rock pushes to the surface (magma)

5. Core Center of Earth About 33% of Earth’s mass
Densest and hottest layer
Made of iron and nickel

6. Physical Structure of Earth
Lithosphere- crust and rigid upper mantle; tectonic plates
Asthenosphere- soft rock of the mantle; how tectonic plates move
Mesosphere- between outer core and asthenosphere
Outer core- completely liquid; iron and nickel
Inner core- solid and dense; iron and nickel

8. Copy the picture.
Outline:
Crust- brown
Mantle- green
Core- purple
Lightly color Earth’s physical divisions.
Lithosphere: blue
Asthenosphere: orange
Mesosphere: red
Outer core: yellow
Inner core: brown

9. Pangea Theory
All continents originally one land mass: Pangea 245 million years ago
Wegener’s Hypothesis: continental drift- single land mass broke up many times over the years and moved to where they are now

10. Tectonic Plates Pieces of the lithosphere that can move
Sit on top of asthenosphere

12. Tectonic Plate Boundaries
Convergent- plates collide
Ex: continental-continental; continental- oceanic; oceanic-oceanic
Divergent- plates separate
Ex: sea-floor spreading
Transform- plates slide past each other
Ex: San Andreas Fault in CA

13. Subduction occurs at convergent boundaries with oceanic crust.

14. Continental-Continental collisions can sometimes form mountains.

15. Sea-Floor Spreading
Happens at mid-ocean ridges (underwater mountain chains)
Sea-floor spreading: new oceanic lithosphere forms when magma rises to the surface and becomes solid
This happens because tectonic plates spread apart

19. What can happen at boundaries?
Convergent- earthquakes, volcanoes, mountains
Divergent- earthquakes, volcanoes
Transform- earthquakes

20. Faults Rock layers can break with stress
Faults- where rocks break and slide past each other
There’s always a fault at a transform boundary (ex: San Andreas)
Faults can be at other places (ex: New Madrid runs through Memphis)

21. Earthquakes Seismology- study of earthquakes
Seismic waves- energy waves that travel away from earthquakes
Body waves (P and S)
Surface Waves- travel slowly and are very destructive

22. P Waves Pressure/primary waves
Travel through solids, liquids, and gases
Fastest
First waves detected

23. Cannot travel through liquid/ bend around the outer core
S Waves
Secondary waves
Second fastest
Stretch rock sideways
Cannot travel through liquid/ bend around the outer core

24. Seismographs determine:
•Magnitude: the size of the earthquake (Richter Scale)
•Depth: how deep the earthquake was
•Location: where the earthquake occurred

27. Magnitude Estimated Effects Effects of Different-Sized Earthquakes 2.0
can be detected only by seismograph
3.0
can be felt at epicenter
4.0
can be felt by most people in the area
5.0
causes damage at epicenter
6.0
can cause widespread damage
7.0
can cause great, widespread damage

28. Volcanoes
Magma rises because magma is less dense than the rock around it
Occur at mid-ocean ridges, subduction zones, and hotspots
Hotspots are not at plate boundaries