1. Crust:
* Composition: Primarily composed of igneous, metamorphic, and sedimentary rocks. The most common elements are oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium.
* Types:
* Continental Crust: Thicker (30-50 km), less dense, and composed mostly of granite.
* Oceanic Crust: Thinner (5-10 km), denser, and composed mostly of basalt.
2. Mantle:
* Composition: Mostly solid rock, primarily composed of silicate minerals like olivine and pyroxene. It also contains iron, magnesium, calcium, and aluminum.
* Layers:
* Upper Mantle: Extends to about 660 km depth. The uppermost part, called the lithosphere, is rigid and includes the crust. Below the lithosphere is the asthenosphere, a partially molten zone that allows for tectonic plate movement.
* Lower Mantle: Extends to about 2,890 km depth. The pressure and temperature increase significantly, making the rock behave more like a viscous fluid.
3. Outer Core:
* Composition: Composed of molten iron and nickel, with smaller amounts of sulfur, silicon, and oxygen.
* State: Liquid, as the intense heat and pressure overcome the forces holding the atoms together in a solid state.
* Key Role: Generates the Earth's magnetic field through the movement of molten iron.
4. Inner Core:
* Composition: Primarily solid iron with a smaller amount of nickel.
* State: Solid, despite extremely high temperatures due to immense pressure.
* Properties: Extremely dense, estimated to be about 12.8 g/cm³.
Beyond the Layers:
* Atmosphere: A layer of gases that surrounds the Earth, primarily composed of nitrogen, oxygen, and argon.
* Hydrosphere: All the water on Earth, including oceans, lakes, rivers, and groundwater.
* Biosphere: All living things on Earth.
Note: The boundaries between layers are not sharp and distinct, but rather zones of gradual transition.
