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The Earth's Inner and Outer Structure

To better understand the Earth, geographers distinguish among the Inner and the Outer Structure. 

The Inner Structure of the Earth refers to the different layers that compose the planet: inner core, outer core, matnle and crust. 

The Outer Structure refers to the spheres that interact on the surface of the Earth, on the crust, creating the landscapes and living conditions that surround us: lithosphere, hydrosphere, biosphere and atmosphere. 

The Inner Structure of the Earth

The Earth has four layers:

  • The crust: solid outer part of the Earth’s surface. It represents around a 1% of the Earth. Temperature: around 22ºC. State: Solid. Composition: Minerals and metals. 

  • The mantle:  located under the crust. It represents 84% of the Earth. It is formed by some solid materials but mainly by melted rocks that forms the magma. Temperature: 1.400ºC - 3.000ºC. State: Liquid and solid. Composition: iron, oxygen, silicon, magnesium and aluminium.

  • The core: the inner part of the Earth. It represents 15% of the Earth. It has two parts:

    • The inner core which is extremely hot but solid as its materials are under high pressure. Temperature: 5.000-6000º C. State: solid. Composition: iron and nickel

    • The outer core which is also very hot but formed by melted materials. Temperature: 4.000-6.000º C. State: liquid. Composition: iron, nickel, sulphur and oxygen.

The Outer Structure of the Earth

Our living conditions arise from the combination of different elements. To better understand them, geographe organize them into four interconnected spheres. 

  • Lithosphere/Geosphere

  • Hydrosphere

  • Biosphere

  • Atmosphere

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