2. 1. What is the crust?1.The crust is the outmost layer of the earth.  Is made of hard rocks  contains silicon and oxygen (silicates) and aluminum  5 km to 50 km thick http://videos.howstuffworks.com/hsw /6222-mountain-building-earths- inner-crust-video.htm

3. 2. What is the mantle? 2. The mantle is the middle layer of the earth  contains lots of iron and magnesium silicates  makes up 82% of earth’s volume and 68% of earth’s mass

4. 3. What is the core? 3. The core is the innermost layer of the earth  contains iron and nickel metals  very dense  makes up 16% of earth’s volume and 32% of earth’s mass http://videos.howstuffworks.com/science- channel/29142-100-greatest-discoveries- the-core-of-the-earth-video.htm Core Mantle Crust

5. Core Mantle Crust Chemical Inner Core Outer Core Mesosphere Lithosphere Asthenosphere Physical

6. 4. What is the lithosphere? 4. The lithosphere is a cool, solid outer layer of the earth  includes the crust and outer mantle  100 km thick  floats on the plastic asthenosphere

7. 5. What is the asthenosphere? 5. The asthensoshpere is a hot semi-liquid layer of the mantle just below the lithosphere.  Is soft and flows.

8. 6. What is the mesosphere? 6.The mesosphere is a solid layer of the inner mantle.  Pressure keeps rocks from melting.

9. 7. What is the outer core? 7.The outer core is a liquid inner layer  Mostly liquid iron  Thought to be the source of the earth’s magnetic field.

10. 8. What is the inner core? 8.The inner core is the innermost part of the earth.  4000 o C – 4500 o C

12. 9. Who was Alfred Wegener 9. Around 1912, Wegener, a German geologist and astronomer, proposed that continents move Pangaea – supercontinent formed when all of earth’s landmasses were joined Scientists didn’t believe him for almost 50 years

14. 10. What evidence supports Pangaea? 10.  Fossils of same species on all continents  Same rock formations across continents  Ancient glaciers were in the tropics

16. 11. When and how was the ocean floor mapped? 11. The ocean floor was mapped in the 1950s using sonar. http://videos.howstuffworks.com/hs w/9068-discovering-math- measuring-distance-and-depth- video.htm

17. 12. How does sea floor spreading occur? 12.  Mid-ocean ridge is a huge crack where the hot mantle pushes upward.  Crust is older as you move outward from the ridge Magnetic field reverses

18. http://videos.howstuffworks.com/hsw/2656 0-earth-science-the-spreading-seafloor- video.htm

19. 13. Describe plate tectonics 13.  Lithosphere is divided into plates that constantly move  Continental Plates – lighter  Oceanic Plates – heavier http://videos.howstuffwork s.com/hsw/8638-inside- the-earth-continental- drift-video.htm

20. 14. What are divergent boundaries? 14. Divergent boundaries are plates that move apart. Examples: Mid-oceanic ridge Great Rift Valley in Africa

21. 14. What are convergent boundaries? 14. Convergent plates occur when plates run into each other ( subduction zone) Examples: Oceanic to oceanic – Japan Oceanic to continental – Andes Mountains in South America Continental to continental – Himalayan Mountains in Asia

22. Oceanic to continental – Andes Mountains in South America Continental to continental – Himalayan Mountains in Asia

24. 15. What is a transform boundary? 15. In a transform boundary, plates slide in opposite directions. Example: San Andreas Fault, California