Four layers of the Earth
Why in news:
- Recently scientists found that there is an inner core with in the inner core itself.
The layers of Earth are:
- Crust – 5 to 70 km thick
- Mantle – 2,900 km thick
- Outer Core – 2,200 km thick
- Inner Core – 1,230 to 1,530 km thick
1. Crust:
- It is the thin (relatively) outermost layer that wraps around the Earth and ranges in temperature from 500 to 1,000°C.
- The crust is split into two types, continental and oceanic. Earth’s crust is 5 to 70 km thick.
- Continental crust makes up the land on Earth, it is thicker (35 – 70 km), less dense and mostly made up of the rock granite.
- Oceanic crust makes up most of the ocean, it is thinner (5 – 7 km), denser and mostly made up of the rock basalt.
- The crust makes up only 1% of the volume of Earth.
2. Mantle:
- Just below the crust lies the mantle.
- The mantle is semi-liquid, sort of like a malleable plastic and makes up 84% of Earth’s volume.
- Earth’s mantle is 2,900 km thick and is broken down into 3 main zones, the lithosphere, asthenosphere, and mesosphere.
- The lithosphere is a bit confusing since it makes up both the lower part of the crust and upper part of the mantle.
- It is about 100 km thick and consists of the 15 major tectonic plates on Earth.
- The asthenosphere is where the mantle turns much more fluid and flows, allowing the above lying tectonic plates to drift across Earth.
- The deepest part of the mantle is the mesosphere where temperatures and pressures get so high that the rock becomes more rigid and doesn’t flow as easily.
- The most common mineral in the mantle is olivine, which is also known as peridot when the mineral is gem quality.
3. Outer Core:
- The outer core lies beneath the mantle.
- This liquid iron and nickel layer spins as the planet rotates and creates Earth’s magnetic field.
- This magnetic field helps to protect us from the Sun’s solar radiation.
- The outer core is 2,200 km thick and very hot at up to 6,100°C.
4. Inner Core:
- The inner core is the deepest layer on Earth.
- It is also made up of iron and nickel but the pressure is so high that it is no longer liquid.
- The temperatures in the inner core are as hot as the surface of the sun, about 5505 °C. Earth’s inner core is 1,230 to 1,530 km thick.
Syllabus: Prelims; Geography
