17.3 NOTES: PLATE TECTONICS
-- The outer shell of the Earth is known as the lithosphere. It makes up the solid, relatively rigid outer shell of the Earth. It is broken up into pieces called plates (tectonic plates). These plates are made up of 2 different types of material: -- oceanic crust (makes up the ocean floor) (denser) Made up of the rock type: Basalt
(a denser, darker-colored rock that is high in iron and magnesium)
-- continental crust
(what we live on)
(less dense) Made up of the rock type: Granite
(a less-dense, lighter-colored rock made up of feldspar & quartz)
Some plates are mostly made up of oceanic crust. Some plates are mostly made up of continental crust. Some plates are made up of partly oceanic and partly continental. ====================================================================================== Layers of the Earth: Inner Core – solid nickel & iron Outer Core – liquid nickel & iron
The flowing material here creates the magnetosphere
Mantle Lower Mantle – More solid-like Upper Mantle – Plastic-like (plasticity) (asthenosphere) Lithosphere – Solid, rigid outer shell (continental & oceanic crust)
These tectonic plates “float” on top of the next layer of the Earth which is called the asthenosphere. It is a layer of rock found in the upper part of the mantle. It is unique in that it is a solid but it has the ability to flow like a liquid. This is known as plasticity. -- What causes this rock to be plastic-like is: * The intense pressure from the weight of the lithosphere * The great heat coming up from within the earth -We think that a lot of this heat is created from radioactive decay -Evidence of this occurring: Radon Gas (# 2 leading cause of lung cancer)
There are 3 types of plate boundaries:
* Divergent - plates moving apart
* Convergent - plates coming together * Transform - plates sliding past one another
Divergent:
2 plates moving away from each other
Rift Valley
As the plates move away from...