How do Rocks Form?

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All of the rocks on Earth are nothing more than clumps of minerals that are bound together in some way.  The mineral pieces can become bound together in several different ways, which results in several different types of rocks.

3 Types of Rocks

All rocks are classified into one of three different groups based on HOW IT FORMS.   


Igneous Rocks

Igneous rocks form from the cooling and hardening of magma or lava. 

Magma is melted rock inside the Earth.

 Lava is melted rock flowing across Earth's surface.   


Sedimentary Rocks

Sedimentary rocks form from sediments that get buried, compacted, and cemented together into a single rock layer.

Sediments are tiny loose pieces of rock, minerals, shells, plant and animal remains. 


Metamorphic Rocks

Metamorphic rocks from when any other rock is exposed to extremely intense heat and pressure.  

The heat and pressure cause the rock to change into a new metamorphic rock. 

The Rock Cycle

Because the Earth is a dynamic place, through various processes rocks can change from one type to another type.  This is explained as the rock cycle, which can also be found in your ESRT:

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Put simply this table explains how each type of rock can be changed into any other type of rock:

  • Any rock can become Igneous if it is melted, cools and hardens
  • Any rock can become sedimentary if it is broken by weathering and erosion and the pieces are cemented together
  • Any rock can become metamorphic if it is exposed to intense heat and pressure