1. Crust:
* Composition: Primarily composed of igneous, sedimentary, and metamorphic rocks.
* Types:
* Continental Crust: Thicker (30-70 km), less dense, and older than oceanic crust.
* Oceanic Crust: Thinner (5-10 km), denser, and younger than continental crust.
* Characteristics: The outermost, rigid, and brittle layer. It's the layer we live on, and it is broken into tectonic plates that move and interact.
2. Mantle:
* Composition: Mostly composed of silicate minerals, rich in iron and magnesium.
* Layers:
* Upper Mantle: Includes the lithosphere (rigid, includes the crust) and the asthenosphere (partially molten, allows for plate movement).
* Lower Mantle: Solid, but behaves more like a very viscous fluid over geological time.
* Characteristics: Largest layer by volume, about 84% of Earth's total volume. The movement of the mantle drives plate tectonics.
3. Outer Core:
* Composition: Liquid iron and nickel with trace amounts of sulfur, silicon, and oxygen.
* Characteristics: Extends from about 2,900 km to 5,100 km depth. The movement of the liquid iron in the outer core generates Earth's magnetic field.
4. Inner Core:
* Composition: Solid iron and nickel with trace amounts of other elements.
* Characteristics: Extends from 5,100 km to the center of the Earth at about 6,370 km depth. Extremely hot, estimated to be around 5,200°C. The inner core's solid state is due to immense pressure, despite the high temperature.
Note: The boundaries between the different layers are not sharp lines, but rather transition zones where the composition and properties change gradually.
