What are the two force which causes earth movement
Answers
Answer:
a. Gravity-Gravity is the primary force that controls the orbit of the planets around the sun. ...
b. Inertia. ...
c. Gravity Working with Inertia. ...
d. Velocity and Gravity.
Explanation:
They are brought about by tectonic forces which originate and operate in the interior of the earth e.g. tensional forces (which operate along horizontal plane moving away from each other), compressional forces (which operate along horizontal plane moving towards each other), shear forces (which move past each other with unequal strength) and gravitational forces (which attracts things to the earths centre).
Earth movements are of 2 types:
1. Horizontal/lateral/orogenic movements
2. Vertical/epeirogenic movements
Horizontal Earth Movements
-Movements which act along a horizontal plane within crustal rocks.
They are caused by tensional and compressional and shear forces.
Effects
They cause:
Strain and stretching of crustal rocks due to stretching caused by tensional forces which cause formation of cracks or faults.
Squeezing and shortening of crustal by compressional forces rocks which cause them which also cause formation of faults.
Crustal rocks to shear by slipping past each other or by dividing into layers which is caused by shear forces.
Results of Horizontal Earth Movements
-results in the formation of the following features:
1. Faults
2. Rift valleys
3. fold mountains
4. Escarpments
5. Basins
6. Tilt blocks
7. Block mountains
Vertical Earth Movements
-Movements which occur along the earth’s radius or towards the earth’s surface or towards its centre.
Effects
Causes:
Subsiding/sinking/downwarping or pulling of crustal rocks downwards.
Uplifting/upwarping or pushing of crustal rocks upwards
Tilting of crustal rocks or shearing in vertical direction due to grater uplift on one side.
Results of Vertical Earth Movements
1. Raised cliffs
2. Tilt blocks
3. Rift valleys
4. Fault scarps/escarpments
5. Plateaus
6. basins
Causes of Earth Movements
(a) Magma movement within the earths crust.
(b) Gravitational force
(c) Convectional currents in the mantle
(d) Isostatic adjustment
Gravitational Force
-When the attractive force of the earth pulls crustal rocks into empty spaces left after magma escaping from the reservoir.
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.
Theories Explaining the Earths Movements
A theory is reasoned ideas intended to explain facts or ideas.
There are 2 theories which explain the earth’s movements namely the Continental Drift Theory and the Plate tectonics theory.
i)Theory of Continental Drift
Its proponent was A. Wegener.
It explains the origin of 6 continents.
Evidences Supporting the Theory
1. Fitting of western coast of Africa and S. America into a jigsaw.
2. Discovery of coal 40◦N and 55◦N which was formed by burying of tropical vegetation.
3. Considerable displacement of rocks along some faults e.g. along the Great Glen Fault of Scotland.
4. Cape and Buenos Aires folds resemble one another by having east west trend.
5. Red sea shores show evidence of having undergone lateral displacement an indication that it was formed by movement of the earth’s crust.
6. Evidence of ancient Glaciation to the south of equator in Africa in Madagascar and India where there is presence of ancient glacial deposits suggesting these areas were once around south pole.
The forces that act in the interior of the earth are called as endogenic forces, while the forces that work on the surface of the earth are called exogenic forces. Endogenic force causes earthquakes and volcanic eruptions. Exogenic force causes weathering, erosion and deposition.