A. 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 aluminum.
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.
B. Mohorovicic Discontinuity (Moho)
• A definite zone of discontinuity between the crust and the mantle.
• Was discovered by Dr. Andrija Mohorovicic in 1909.
The Mantle/ Asthenosphere
• Layer lying between the crust and the core
• Made of iron and magnesium
• Has two layers
• Upper mantle
• Rocks are more elastic than those of sima.
• Temperature is about 1000◦c.
• lower mantle
• Rocks are like very viscous liquid.
• Temperature ranges between 1000◦c to 3000◦c.
Gutenberg Discontinuity
A definite zone of discontinuity between mantle and core.
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.
The Atmosphere
Layer of gases surrounding the earth.
The earth revolves with it because its held onto it by gravity
It’s about 330km thick.
Composition of the Atmosphere
Gases-exist as a mixture
Smoke particles
Dust particles
Water vapour.
G. Hydrosphere
Ocean and seas
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