A. 3 Main groups

1. Earth’s composition
2. Continental Drift
3. Sea floor itself

B. Earth

1.Core-mostly iron

2.Furthest from earths surface it affects earth’s surface condition because it’s the source of earth’s magnetic field

3.Magnetic Dynamo generates magnetic field (mechanism that turns energy from fluid motions into electrical currents

C. Mantle

4. Difficult to observe by geologists
5. Formed of solicited materials (minerals rich in silicon and oxygen)
6. Changes deeper you go because of temp and pressure change
7. Affect seismic wave velocities, which prove to be important with P.T.
8. Crust/Upper mantle to move relative to underlying mantle.

D.Crust-Upper most layer

9. Varies thickness and composition

-Continental crust=underlies the continents

-Oceanic crust= "ocean basins both made of solicited material"

E.Continental Drift

10. Form Pangea
11. Fossil found on continents allowing Migration
12. Seafloor magnetic strips=best tool for this theory

F.Sea floor Spreading

13. Since the strips are proved to be caused from spreading taken place by=chains of sub sea volcanic running down center of ocean basins (miss ocean ridges)
14. Newly formed magma is hot and expands>pushes through top of ridges spreads sides apart
15. Occurs symmetrically across axis of the Ridges (lava forms ridges)
16. Then cools and hardens and becomes magnetized in direction of earths magnetic field, which is why there is striped sea floor

G.Geologist ask

17. How continents drift through sea floor
18. Does not-rather continents are connected to plates that constantly move away from one another at mid-ocean ridges