Most of us do not know much about the structure of the earth. Some may say it doesn't matter,but a better understanding of our knowledge of what the earth actually will help us in comprehending many of the events that happen now,those that will happen in the future and even billions of years ago.
From the use of seismic waves,the earth is known to be radially layered like an onion. The boundaries between layers are marked by abrupt velocity gradient. Each layer is characterized by specific physical, chemical properties of density, pressure and temperature.
Three major layers have been distinguished although these can be distinguished also into sublayers
•Crust
•Mantle
•Core
Beneath the oceanic crust is a narrow bed or later with sharp difference in mineral properties and sharp decrease with velocity and is referred to as the 'Mohorovicic Discontinuity' discovered in the year 1909 by a Yugoslavian whom it's so named after.
Below the Mohorovicic discontinuity is the mantl. This seismic discontinuity is the boundary between the crust and Mantle. The mantle has been found to be made up of three layers
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•The upper Mantle; about 80km below the Continental crust and 40km below the oceanic crust. It's rigid
•The Asthenosphere;it's hot,weak,mobile,easily deformed and almost like a liquid. At a depth of about 250km
•The mesosphere also known as the inner mantle is rigid.
Beneath the inner mantle is the outer core. It's molten and contains lots of heavy metals.
The inner core is about 600km in depth,made up of iron and silicates.
Studies have shown that the crust and upper Mantle are rigid and float on the mobile Asthenosphere. This rigid region is collectively known as the Lithosphere.
>The Lithosphere because of it's rigidity is brittle and when subjected to stress,fractures. This is what gives rise to earthquakes.
THE CRUST
This is the hard outer layer on which we live on. It is made up predominantly of igneous , metamorphic , and sedimentary rocks. The mountains and highlands are part of the crust. It is the coldest layer because it is exposed to the atmosphere. The crust is of two different types.
•continental crust
•oceanic crust
The continental crust is thicker than the oceanic crust.
THE MANTLE
It is the second layer of the Earth. The temperature of increases as you get closer to the Inner Core.Its also the largest layer of the Earth.
THE CORE
The temperature at the inner core's surface is approximately 5,430 °C. The outer core is molten.
I hope you enjoyed the ride. Thanks for reading.