Thomas chinnappan geologist keeranur, pudukkottai, tamilnadu, india.

1. INTERNAL STRUCTURES
OF EARTH
BY:
THOMAS CHINNAPPAN . A ,
M.SC.APPLIED GEOLOGY,
PERIYAR UNIVERSITY,
SALEM.

2. Internal Structures of Earth
The earth is made up of three different
layers:
 Crust:
Oceanic Crust
Continental Crust
 Mantle:
Upper Mantle
Lower Mantle
 Core:
Inner Core
Outer Core

3. CRUST:
Outer most and thinnest layer, Its relatively cool and consist of
hard rocks.
Oceanic crust is about 5-10 km thick, basaltic composition
dominated by silica and magnesium (SiMa).
Continental crust is about 20-40 km thick but under mountain
it can be 70 Km thick, composition is granitic (Silica and
Aluminium dominantly).
The crust is much thinner than any of the other layers, and is
composed of the least dense potassium (K), calcium (Ca) and
sodium (Na) aluminum-silicate minerals.
At the bottom of the Crust, the velocity of earthquake waves
increase abruptly as they enter dense layer called “Mantle”.
The crust-mantle boundary is known as the “Mohorovicic
discontinuity”.

5. MANTLE:
The mantle lies directly below the crust.
It is almost 2900 kilometers thick and makes up 80 percent of the
Earth's volume. Chemical composition may be similar throughout
the mantle.
 Temperature and pressure increase with depth resulting strength
of mantle rock to vary with depth, and create layering within the
mantle.
 The upper part of the mantle consists of two layers
1) Lithosphere
2) Asthenosphere

6. LITHOSPHERE:
 Outer part of the Earth
including both the uppermost
mantle and the crust, make
up the lithosphere its
mechanical behavior is similar
to that of the crust.
 The lithosphere can be as thin
as 10 kilometers where
tectonic plates separate.
 The lithosphere is about 75
kilometers thick beneath
ocean and 125 kilometers
under the continents. A
tectonic (or lithospheric) plate
is a segment of the
lithosphere.

7. ASTHENOSPHERE:
The asthenosphere extends from the base of the lithosphere to a
depth of about 350 kilometers.
Increasing temperature with depth gradually, as a result small
degrees of partial melting, possibly as much as 10% in regions of
high heat flow.
This partial melt is an important source of magma and a lubricant
to ease the tectonic movements of the lithospheric plate.
This change in rock properties occurs over a vertical distance of
only a few kilometers.
This zone also called as low velocity zone where the velocities of
s wave is decrease.

8.  It is mostly Composed of mostly silicon, oxygen, magnesium and iron.
 Texture is plastic like which has the characteristic of a solid but flows like a liquid when under
pressure Approximately 2885 km thick.
 Has large convection currents that drive the movement of the plates.

9. CORE:
 Core is the innermost of the Earth's layers.
 Outer core: 2900 to 5150 km (liquid)
 Inner core: 5150 to 6370 km (solid).
 Over all it is a sphere with a radius of about
3470 kilometers and is composed largely of iron
and nickel and have a density about 12 x 103
Kg/m³.
 Near its center, the core's temperature is about
6000°C, as hot as the Sun's surface. The
pressure is greater than 1 million times that of
the Earth's atmosphere at sea level.
 This extreme pressure overwhelms the
temperature effect and compresses the inner
core to a solid.
 The core is composed mostly of iron (Fe) and is
so hot that the outer core is molten, with about
10% sulphur (S).

10. THANK YOU