Inside Our Earth
The earth is a dynamic planet i.e. it continuously undergoes changes. These changes are:
- Inside the earth
- Outside the earth
Interior of the earth
The earth is made up of several concentric layers. Concentric means having a common centre. The arrangement is like a ball inside another ball which is inside a third ball.
Broadly, there are three layers of the earth:
- Crust
- Mantle
- Core
The Crust
It is the outermost layer over the earth's surface. It is
- The thinnest of all the layers.
- About 35 km on the continental masses and only 5 km on the ocean floors.
The main minerals constituting the continental mass are:
- Silica
- Alumina
The continental mass is also called sial. The name sial is derived from letters si of silicon and al of alumina.
The main mineral constituents of the oceanic crust are:
- Silicon
- Magnesium
The oceanic crust is called sima. The root of the word sima is si from silica and ma from magnesium.
Mantle
It is the layer just beneath the crust and extends up to a depth of 2900 km below the crust.
Core
It is the innermost layer i.e. it is below the mantle. Its radius is about 3500 km. The core consists of outer core and inner core. It is mainly made up of:
- Nickel
- Iron
The innermost layer is also called nife. The name nife is derived from the word ni from nickel and fe from ferrous meaning iron. The temperature and pressure of the central core is very high.