THE STRUCTURE OF THE EARTH (Internal Structure)

Internal Structure of the Earth

The evidence used to study the earth’s interior are

1. mining
2. drilling
3. quarrying/excavation
4. Crust/Lithosphere

• Outermost layer of the earth
• Made of soils and other loose deposits of sand
• The dominant rocks are granites.
• Extends 0-50km
• Has 2 layers

1. Sial

• Also called continental crust
• Made of light coloured rocks
• Called sial because it’s made up of silica and aluminium.

2. Sima

• Also called oceanic crust
• Mainly made of basaltic rocks which are brittle.
• Called sima because it is made of silica magnesium and iron.

 

Mohorovicic Discontinuity (Moho)

• A definite zone of discontinuity between the crust and the mantle.
• Was discovered by Dr. Andrija Mohorovicic in 1909.

1. The Mantle/Asthenosphere

• Layer lying between the crust and the core
• Made of iron and magnesium
• Has two layers

1. Upper mantle

• Rocks are more elastic than those of sima.
• Temperature is about 1000◦c.

2. lower mantle

• Rocks are like very viscous liquid.
• Temperature ranges between 1000◦c to 3000◦c.

 

Why the Interior of Earth Is Very Hot

1. a) Due radio-active decay causing most of the heating.
2. b) Due to great pressure as a result of overlying crustal materials.
3. c) The original heat resulting from slow cooling of the materials which were pulled off the sun

 

Gutenberg Discontinuity

• A definite zone of discontinuity between mantle and core.

1. Core/barysphere/Centrosphere

• The innermost/central layer of the earth.
• Has 2 layers

Outer Core

• Composed of very dense rocks
• Made up of nickel and iron
• Temperatures are up to 3700◦c.

Inner Core

• A solid mass of mainly iron
• Temperatures are estimated to be 4500◦c to 5000◦c.

 

See also

BUSH FALLOWING IN WEST AFRICA

MINING

MINERALS IN EAST AFRICA

PROBLEMS ENCOUNTERED IN FIELD WORK

MINERALS AND ROCKS