1. Earth’s Interior and Plate Tectonics

2. Earth’s Composition:
Not just solid rock
Distinct layers
Each layer has certain physical properties

3. 3 Main Layers when dividing them by their composition
Crust
Mantle
Core

5. Crust Outermost layer 5 – 100 km thick Thinnest layer
High in Silicon and Oxygen (makes rocks called silicates)
< 1% of Earth’s mass

6. Average thickness of 30 km Composition similar to granite
Continental Crust
Average thickness of 30 km
Composition similar to granite

7. Average thickness from 5-8 km Composition similar to basalt
Oceanic Crust
Average thickness from 5-8 km
Composition similar to basalt

8. Oceanic crust is more dense than Continental crust

9. Mantle Between crust and core
Extremely thick and 66% (2/3) of Earth’s mass
Large amounts of Calcium and Magnesium

10. 33% (1/3) of Earth’s mass 2 separate layers Mostly Iron and Nickel
The Core
33% (1/3) of Earth’s mass
2 separate layers
Mostly Iron and Nickel

11. There are 5 layers when we divide them up by their physical properties
Lithosphere
Asthenosphere
Mesosphere
Outer Core
Inner Core

12. Made of the Crust and Upper Mantle Rigid, solid, cool
Lithosphere
Made of the Crust and Upper Mantle
Rigid, solid, cool
About 150 km thick

13. Lithosphere is broken into tectonic plates

14. Asthenosphere Upper part of the mantle 1-5% liquid rock
Flows like putty, or plastic (very viscous)
Lithosphere (tectonic plates) slide around on the asthenosphere

15. Mesosphere The middle layer when dividing them up into 5 parts
Same as the mantle
About 1% liquid
High viscosity
Flows very slowly

16. Hot, but not as hot as the inner core
Outer Core
Liquid layer
Hot, but not as hot as the inner core

17. Inner Core Solid and most dense layer
6,000o Celsius (hotter than Sun’s surface)
So why is it solid?

20. Some plates contain both continental and oceanic crust

23. How do we know what the Earth’s interior looks like?

24. 12.2 km into the earth Kola Pennisula, Russia 1984
Deepest hole drilled:
12.2 km into the earth
Kola Pennisula, Russia 1984

25. Seismic Waves From earthquakes There are 3 different types
Travel through earth’s layers
Transmission depends on phase (density) of the layer

28. But why do tectonic plates move?

29. Convection Currents
The next time you heat anything like soup or water in a pan you can watch the convection currents move in the liquid. When the convection currents flow in the asthenosphere they also move the crust. The crust gets a free ride with these currents, like the cork in this illustration.

30. Dynamics of the mantle…