Endogenic Processes
➡️ are processes involving the use of energy from deep within the Earth
➡️ are responsible for volcanism and plate movement.
Why is the Earth's interior hot?
➡️ The source of this heat is attributed to leftover heat from its formation 4.45 billion years ago as
gravitational energycaused particles to accrete and collide with each other.
➡️ Another source of Earth's internal heat is the disintegration of natural radioactive elements inside
earth.
➡️ Scientists estimate that temperatures in the Earth's core are between 5000 to 7000 degrees Celsius.
Magmatism
➡️ Magma - The molten rocks that are found beneath the Earth's surface.
➡️ Magmatism refers to the formation and movement of magma. Magma is formed when conditions are
right to cause preexisting solid rocks to melt.
Magma can be generated in several ways:
> Decompression Melting - melting occurs when the temperature stays the same but the pressure
decreases.
> Flux Melting - when volatiles or gaseous substances are added into the hot solid rocks.
> Heat Transfer Melting - melting of surrounding rocks caused by very hot magma bringing in additional
heat.
Plutonism
➡️ Is the process by which magma rises through the crust and crystallizes as an intrusive igneous rock
beneath the Earth’s surface.
Volcanism
➡️ Volcanoes - are visible manifestation of the process of rock formation. It is a vent that serves as the
conduit of lava or the molten rock that reaches the Earth's surface.
➡️ Volcanism is part of the process of bringing material from the deep interior of a planet and spilling it
forth on the surface.
➡️ The difference in temperature of the magma compared to the sorrounding rocks allows it to become
more bouyant to rise to the surface.
Types of Volcanoes
> Shield Volcano - shield volcanoes are like very broad shield with very low slopes because runny lava
tends to spread easily.
> Cinder Cones - are mostly made with pyroclastic fragments which sustains steep slopes.
> Stratovolcanoes or composite Volcanoes - are alternating layers of lava and pyroclastic materials.
Metamorphism
➡️ is the change that takes place within a body of rock as a result of it being subjected to conditions that
are different from those in which it formed. Pressure and temperature plays a huge role in this process.
➡️ During metamorphism the protolith undergoes changes in texture of the rock and the mineral make
up of the rock. These changes take place mostly in the solid state and are caused by changes in physical
or chemical conditions, which in turn can be caused by such things as burial, tectonic stress, heating by
magma or interactions with fluids.
Behavior of Rocks Under Different Types of Stress
> Compression - is the stress that squeezes rocks together, this causes rocks to fold or fracture.
> Pulling Apart - rocks that are being pulled apart are under tension. Tension causes rocks to lengthen or
break apart.
> Shearing - when forces act parallel to each other but in opposite directions, the stress is called shear.
Shear stress causes two planes of material to slide past each other. This is the most common stress
found at transform plate boundaries.