Environmental Science (2+1)

Structure of Earth

Structure of Earth

• The earth is a cold, spherical, solid planet of the solar system which spins on its axis and revolves around the sun at a certain constant distance. The solid component of earth is called lithosphere. The lithosphere is multi- layered and includes following three main layers. 1. Crust 2. Mantle 3. Core. The core is the central fluid or vapourized sphere having diameter of about 2500 km from the center and is possibly composed of nickel-iron. The mantle extends about 2900 km above the core. The crust is the outermost solid zone of the earth and it is about 8-40 km above the mantle. The crust is very complex and its surface is covered with the soil supporting varied biotic communities.


The geologic component layers of Earth are at the following depths below the surface

Depth		Layer
Kilometers	Miles
0–60	0–37	Lithosphere
0–35	0–22	Crust
35–60	22–37	Uppermost part of mantle
35–2,890	22–1,790	Mantle
100–200	62–125	Asthenosphere
35–660	22–410	Upper mantle
660–2,890	410–1,790	Lower mantle
2,890–5,150	1,790–3,160	Outer core
5,150–6,360	3,160–3,954	Inner core