EMMANUEL COLLEGE OF B.Ed

TRAINING, VAZHICHAL

UNIT - 3

IN SEARCH OF

EARTH’S

SECRETS

CONTENTS1. Crust

Continental Crust & Oceanic Crust

2. MantleUpper Mantle & Lower Mantle

3. CoreOuter Core & Inner Core

CRUST

- The comparatively thin outer

shell

of the Earth.

- Approximately 40 km thick.

- Two parts- continental crust &

oceanic crust.

Continental crust andoceanic crust

• As silica and alumina are the chief contents,

the continental crust is also known

as SIAL.

• As silica and magnesium are the chief contents, the oceanic crust is also known as SIMA.

MANTLE

• Located beneath the crust.

• Extends upto 2900 km from

the

crust.• Two parts- upper mantle, lower

mantle.

Upper mantle and Lower mantle

Upper mantle

• The upper mantle, made up of silicon compounds, is in a solid state.

Lower mantle

• The lower mantle, located beneath the

upper mantle, is in a semi-liquid state.

CORE

• Central part of the Earth.

• From 2900 km to 6371 km

• Two parts- outer core, inner core.

Outer core and inner core

• The materials in the outer core are in a

molten state.

• Due to the high pressure prevailing at

the centre, the inner core is in a solid

state.

As it is mainly made up of the minerals

nickel (Ni) and iron (Fe), it is also

known as NIFE.

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