CHAPTER 20

THE EARTH’S LITHOSPHERE

LAYERS OF THE EARTH

1. CRUST 2. MANTLE 3. CORE – INNER AND OUTER CORE

CRUST

Thin outermost layer of the earth Made up of 2 layers of rocks found in the

continental crust: the top layer called GRANITE LAYER and the bottom layer called BASALT LAYER.

Mohorovicic Discontinuity-(moho/M.discontinuity)- boundary bet. The crust and mantle

MANTLE

Layer below the crust Thicker and denser Mostly made up of dense rocks and is

extremely hot

Guttenburg Discontinuity- boundary bet. Mantle and core

OUTER CORE

Made up of liquid iron and nickel Temperature ranges from about 2200 0C –

2400 0C

INNER CORE

Solid, innermost layer of the earth Temperature reaches to about 2500 0C Presence of dense iron may help explain

the existence of the magnetic field around the earth

MATERIALS OF THE EARTH

1. MINERALS 2. ROCKS 3. METALS 4. FOSSIL FUEL

MINERALS

Naturally occurring inorganic crystalline solid with a definite chemical composition

Nonrenewable resources Some are considered precious gem

EXAMPLES OF GEM

ROCKS

Igneous rocks ( fire )

Cooled from molten lava or magma. Ex.

Sedimentary rock

Formed from sediments deposited on the ocean bottom.

Metamorphic rock

Formed from sedimentary and igneous rocks that were subjected to high pressure and temperature.

Weathering – breaking down of rocks

Rock cycle

CHANGES ON THE EARTH’S SURFACE

Diastrophism - movement of the solid part of the earth

FAULT – a crack or fracture in the crust of the earth

FOLDS – are bends in rock layers Mountains are formed due to the upward

movement of molten rocks eventually form as volcanoes.

Plate tectonic theory

Alfred wegener – introduced the idea of Pangea as super continent