admin Tectonic plates
Definition: They are the crusts that float on the mantle of the earth’s surface
Plate tectonics Definition: The process by which the crustal plates are being moved by convection currents
How do plates move?
The force that brings about the motion of the crustal plates comes from the tremendous heat found in the Earth’s interior
This heat causes the rocks in the mantle to melt and become molten rocks called magma
When magma is heated, it expands rises and generates convection currents, which push the plates away from each other.
When it cools, the magma sinks and brings the plates towards each other
This constant rising and sinking of the magma results in the movement of the plates over the Earth’s surface
Volcanoes
Magma rises and squeezes through the widening cracks, sometimes to erupt and form volcanoes
Formation of Rift Zones
The rising magma puts more pressure on the crust to produce additional fractures and, ultimately, the rift zones
Formation of the Mid-Atlantic Ridge
Divergent plate movement causes fractures and cracks to develop at the plate boundary. Magma from the mantle begins to flow out from the cracks. When this magma solidifies, new crust is formed at the plate boundary
The constant flow magma along the Mid-Atlantic Ridge causes new crusts to form continuously and the old crust to be pushed further and further away from the plate boundary
Subduction
When an oceanic plate collides with a continental plate, the thin and dense oceanic plate will bend underneath the thicker but less dense continental plate
Gradually, the oceanic plate is pushed down into the depth of the molten upper mantle where it is melted into molten rock.
Fold mountains
The less dense continental plate moves over the denser oceanic plate. The crusts at the plate boundary gradually folds, rises and crumples to form fold mountains
Volcanoes
The crust eventually melts as it moves deeper into the hot mantle. Magma is formed, which due to its lower density, rises to the surface, leading to volcanic eruptions
It is therefore quite common to find active volcanoes where convergent plate movement takes place
Definition of a volcano
A mountain or a hill formed of materials from the Earth’s interior that have been ejected under pressure from a vent
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Trench
Definition: The oceanic plate is subducted forming a depression, which is a trench.
The convergence of two oceanic plates usually results in one being subducted under the other, leaving a depression, known as a trench.
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