Plate Tectonics Notes

The theory of plate tectonics is based on the theories of continental drift and seafloor spreading.
It explains geological phenomena like:
- Formation of mountains
- Occurrence of earthquakes and volcanic eruptions
- Distribution of mineral and energy resources
Definition: A scientific model that describes the movement and behavior of the Earth's lithosphere (outermost layer).

Earth’s outermost solid layer is the crust, which consists of huge slabs of rock called tectonic plates.
These plates are made of rigid lithosphere and are constantly moving and interacting.
Definition: Massive rigid slabs of solid rock made up of Earth's lithosphere (crust and upper mantle).
There are seven extremely large plates (bigger than most continents).
There are about ten medium-sized plates and around 60 smaller plates.
Tectonic plates move slowly over the asthenosphere (partially molten and ductile layer of the Earth's mantle).
They vary in size, shape, and thickness and are constantly moving across the surface of the Earth.

The movement of tectonic plates is explained by the Convection Theory.
The Convection Theory states that hotter, less dense matter rises, and cooler, denser matter falls.
Hotter magma near the core rises and pushes the continental crust.
Magma in the mantle heats up and rises towards the crust.
As it loses heat and cools down, it sinks towards the core, where it heats up again, forming a convection current.

Heat generated by the decay of radioactive materials in the Earth's core causes the temperature of the mantle to rise.
- This causes the rock to melt and become magma.
As the molten material (magma) in the mantle heats up, it becomes less dense and rises upward towards the Earth's surface, specifically towards mid-ocean ridges.
As the less dense material rises to the surface, it cools and becomes more dense, spreading outwards and flowing horizontally, shifting the tectonic plates, before sinking back down towards the Earth's core, creating a convection current.

Tectonic plates are constantly moving and interacting with each other at regions called plate boundaries.
The point where two plates meet is called a plate boundary.
At plate boundaries, the Earth's crust becomes unstable as the plates push against each other or ride under or over each other.
The movement of the plates at plate boundaries can cause geological events such as earthquakes, volcanic eruptions, and the formation of mountains.

At divergent boundaries (constructive boundaries), plates move away from each other.
Divergent boundaries create new crust as magma rises from the mantle, solidifies, and forms new oceanic crust.

Convergent boundaries (destructive boundaries) are places where tectonic plates collide or one plate subducts beneath the other.
Convergent boundaries contribute to the formation of mountains, volcanic activity, and earthquakes.

Transform boundaries (conservative boundaries) occur when two plates slide past each other horizontally at different speeds.
The boundary between the two plates is a transform fault.
The movement along these boundaries can cause earthquakes as the plates grind against each other.