The Structure of the Earth
Due to cooling and rotation, substances in the gas, liquid and solid states separated and formed spherical layers, or shells according to their density. These shells are grouped into the outer and the inner shells.
The outer shells are the atmosphere, biosphere and the hydrosphere. The inner shells are the crust, mantle and the core.
1. External shells
Atmosphere
The outermost shell that covers the Earth. Composed of gases, it is the lightest of the shells.
Biosphere
The system containing all living beings within the lithosphere, lower atmosphere and hydrosphere.
Hydrosphere
The non-contiguous shell containing all the waters in any state on Earth. This includes underground waters locked or trapped in rocks, surface watercourses, lakes, seas, oceans, and water vapour in the atmosphere.
atmosphere
biosphere
hydrosphere
2. Internal shells
Crust
The outermost, solid shell of the planet, with the smallest mass of the inner shells. Its average thickness is 30 km. The composition and thickness of the continental crust and the oceanic crust are different.
Mantle
A 2900 km thick shell of Earth, located between the crust and the core. The outer mantle is composed of a layer of solid rock, with plastic, molten rock underneath (asthenosphere), the inner mantle is solid rock.
Core
The innermost, hot and very dense
part of the Earth, 7,000 km in diameter and composed of iron and nickel.
It is divided into two parts, a molten outer core and a solid inner core.
crust
outer mantle
crust
core
outer mantle
inner mantle
inner mantle
outer core
inner core
The Home of Mankind: the Earth
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The Home of Mankind: the Earth
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