Plate Tectonics Outline

Observations and Inferences:

• An observation is seeing something in a piece of data
• An inference is making an educated guess or drawing a conclusion from your observation

Continental Drift Theory:

• Observed a map and saw that Africa and South America looked like puzzle pieces, making an inference that the continental drift happened
• All the continents were once connected the super continent was called Pangea and then drifted apart
• This theory was created by Alfred Wegener, but no one believed him until sea floors were mapped                                                                                                                                             -In the early 1900s, that idea was very farfetched                                                                           -Alfred Wegener had a few failed theories back then as well

Evidence for Plate Tectonics:

• South America and Africa's rocks have the same graining.
• The diamonds in South America are same kind of diamonds that are found in Africa
• The mountains on Greenland, North America, Europe, and Africa are the same kind of mountains
• The fossils on different continents match up.
• There are glacial scratches that line up on Africa and Australia
• The Mid Atlantic Ridge
• Enough to make a theory

Seafloor Spreading:

• Created by ridges, ie. Mid Atlantic ridge                                                                                          -Mid Atlantic ridge exists because the rocks closer to the base are newer when the the rocks further are older, and each side's pattern of rocks mirrors the other side's
• Mid atlantic ridge supports plate tectonics theory due to magma coming to the Earth's surface and creating a new layer of land, pushing the sea floor on both sides apart. 
• Seafloor structures- formations such as volcanoes, ridges and trenches where landmasses collide or pull apart  

Plate Boundaries:

• Divergent, Convergent and Transform are the types of plate boundaries                                        -Divergent boundaries are when two landmasses that are pulling apart                                          -Convergent boundaries are when two landmasses collide                                                            -Transform boundaries are when when two landmasses slide by each other, one going one way and the other going the opposite

Subduction- where one plate is pushed beneath another

Density:

• Density equals mass divided by volume
• The density below one means the object can float on water, because water's density is one
• If the volume of and object is increased, the density will be lowered 

Layers of the Earth:

• From the inside to the outside: Inner Core, Outer Core, Mesosphere, Asthenosphere and Lithosphere  
• The more common names are Core, Mantle and Crust (in the same order as before)
• The inner and outer core are fluid, with magma, and is at extremely high temperates compared to the other layers 
• The magma from the mantle comes up to the surface and forms a new layer on the mid atlantic ridge, because its density is decreased from the heat to the extent that it must go above the other layers of the Earth (being less dense than those layers)   

Convection- When heat is added to a fluid (liquid or gas), its volume will increase, so it will rise upward as it gets less dense. As it cools down, it will slowly come down. This is very similar to a lava lamp and how to magma comes to the crust of the Earth at places like the Mid Atlantic Ridge

Magnetic Polarity:

• The North and South poles both cause magnetic polarity
• Magma has iron properties in it
• When the North and South Pole change positions, magnetic striping occurs                                 -The new magma comes up with the magnetic pull of the North and South pole. When the magma becomes a rock, the magnetic pull is locked into it. 
• This helps support the continental drift theory because the different stripes of the polarities are identical on both sides.