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 Form 2 Geography Online Lessons on Internal Land Forming Processes

In this lesson we are going to learn about the causes of Earth Movements

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Answer Text:
Causes of Earth Movements
(a) Magma movement within the earth’s crust.
(b) Gravitational force
(c) Convectional currents in the mantle
(d) Isostatic adjustment
1. Magma Movement within the Earth’s Crust
• When magma moves with force pushing crustal rocks horizontally or vertically.
• When magma moves from reservoir and leaves empty spaces onto which crustal rocks are pulled inwards.
2. Gravitational Force
- When the attractive force of the earth pulls crustal rocks into empty spaces left after magma escaping from the reservoir
3. Convectional Currents within Mantle
- When convectional currents in magma in mantle drug crustal rocks by friction. Horizontal movement of currents cause horizontal movements while vertical cause vertical movements.
4. Isostatic Adjustment
-Rising of continental masses to restore the upset state of balance between sial and sima layers.
-Isostacy is the state of balance between sial and sima layers.
It can be disturbed by erosion on continents and melting of continental ice sheets.
-The reduced weight causes continental masses to rise.