Rock Classification Igneous, Sedimentary & Metamorphic

Sedimentary rocks

Sedimentary rocks are a type of rock that is formed by deposition and cementation. In simpler terms, they are formed when sand, mud and pebbles get laid down in layers. There are three types of sedimentary rocks. Clastic, chemical and organic are the three types.

Clastic sedimentary rocks(inorganic)

Clastic type of rocks are formed from pre-existing minerals and rock. Breccia, conglomerate, sandstone, siltstone and shale are all clastic.

Breccia, a type of clastic sedimentary rock.

chemical sedimentary rocks

Chemical sedimentary rocks are formed when dissolved materials precipitate from solution. Some examples of this could be rock salt, dolomite, and limestone

Limestone, a type of chemical sedimentary rock that is also used for building material.

bioclastic sedimentary rocks(organic)

Bioclastic sedimentary rocks are known as organic because they are formed from the accumulation of animal and plant debris. Some examples of this is coal, limestone and dolomite also.

This is coal, which is a very important type of bioclastic rock. It is used for electricity generation and steel production.

where they are found

Sedimentary rocks are usually found covering a good amount of earths upper crust.

This is a map of the united states where sedimentary rocks can be found.

rock cycle

Sediments, who are made from igneous rocks, are spread out and buried. Then they are cemented into the ground and that forms sedimentary rocks.

If you want more detailed information about sedimentary rocks, here's a video.

igneous rocks

Igneous rocks are a type of rock group that are formed when magma or lave cools and solidifies. It is also known as magmatic rock.

extrusive igneous rocks

Extrusive igneous rocks cool above land, which makes them cool faster because of the decent amount of air around it. When it cools faster, the crystals in produces are smaller because they have less time to get bigger. Some extrusive igneous rocks are basalt, obsidian and pumice.

This is obsidian, a mineral used for making sharp weapons and tools.

intrusive igneous rocks

Intrusive igneous rocks crystallize below earths surface, which makes their cooling slower. As a result of this slow cooling the crystals are bigger because they had more time to grow. Some intrusive igneous rocks are diorite, gabbro, granite and pegmatite.

This is granite, a intrusive igneous rock used for indoor and outdoor designing.

where they can be found

Igneous rocks can be found anywhere there has been a volcano. In northern canada, most of their hard rock is made up of igneous rocks.

rock cycle

The melting of metamorphic and sedimentary rocks can make magma, which when cooled and solidified, will be turned into igneous rocks.

If you want to learn more about igneous rocks, here is a video.


A metamorphic rocks form from already existing rocks. They can form from igneous, sedimentary and existing metamorphic rocks. They are formed when they are put under extreme heat and/or pressure. The type of rocks don't melt, but they do recrystallize.

Regional metamorphism

This happens over a large area deep inside the earth. The rocks become distorted and the layers are seen as wavy. The minerals inside align in bands, according to their density. These types of rocks are known as foliated. Some rocks of this type are schist, slate and gneiss.

This is the rock gneiss, which can be used for decorating purposes.

contact metamorphism

Contact metamorphism is when a rock is altered by coming into contact with molten rock. These types are considered nonfoliated and they composed of crystals. Some rocks of this type are novaculite, quartzite and marble.

This is marble, which can also be uses for decorating.

where they can be found

Metamorphic rocks can be found deep below earths surface. Lots of the lower continental crust is made of metamorphic rocks.

rock cycle

When existing metamorphic, sedimentary or igneous rocks are put under heat and/or pressure, that is when metamorphic rocks are made.

Here is a video if you want to learn more about metamorphic rocks.

Created By
Samantha Marino


Created with images by kevin dooley - "Background"

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