Earth is a terrestrial planet with a diverse composition, divided into layers:
1. Core:
* Inner Core: Solid, primarily composed of iron (Fe) with a small amount of nickel (Ni). Temperature: ~5,200°C (9,392°F)
* Outer Core: Liquid, mainly iron and nickel. Temperature: ~4,500°C (8,132°F)
2. Mantle:
* Mostly composed of silicate minerals like olivine and pyroxene.
* Temperature: ~870°C (1,600°F) at the top, increasing to ~3,700°C (6,700°F) near the core.
* Has a semi-solid state, allowing for slow movement over millions of years (plate tectonics).
3. Crust:
* The outermost layer, thin and brittle.
* Two types:
* Oceanic Crust: Dense, composed mainly of basalt and gabbro. Thicker than continental crust.
* Continental Crust: Less dense, composed of various rocks, including granite and metamorphic rocks.
4. Atmosphere:
* Composed primarily of nitrogen (N2) and oxygen (O2).
* Plays a vital role in regulating Earth's temperature and weather.
5. Hydrosphere:
* Includes all the water on Earth, including oceans, lakes, rivers, and groundwater.
* Essential for life and plays a role in weather and climate.
The crust is further divided into two types, with distinct compositions:
1. Oceanic Crust:
* Primarily composed of mafic rocks:
* Basalt: A dark-colored, fine-grained, volcanic rock rich in magnesium and iron.
* Gabbro: A coarse-grained intrusive equivalent of basalt.
* Also contains minor amounts of peridotite, a dark green rock rich in olivine and pyroxene.
* Average thickness: 5-10 km (3-6 miles).
2. Continental Crust:
* Composed of a wider variety of rocks, including:
* Granite: A light-colored, coarse-grained, igneous rock rich in quartz and feldspar.
* Sedimentary Rocks: Formed from the accumulation of sediments, including limestone, sandstone, and shale.
* Metamorphic Rocks: Formed from pre-existing rocks that have been transformed by heat, pressure, or chemical reactions.
* Average thickness: 35-70 km (22-43 miles).
In summary:
* Earth is composed of a core, mantle, crust, atmosphere, and hydrosphere.
* The crust is the outermost layer, with two distinct types: oceanic and continental.
* Oceanic crust is dense and primarily composed of basalt and gabbro.
* Continental crust is less dense and composed of a wider variety of rocks, including granite, sedimentary rocks, and metamorphic rocks.
