Earth’s Crust Facts

When you look at the Earth, you might think that it is one giant and solid planet but that isn’t true!  The Earth is made up of many, many layers and the Earth’s crust is the part of the Earth that is the outermost layer.  This is the layer of the Earth that people, animals, and insects live.  This part of the Earth also has mountains, oceans, and more.

Earth cutaway from the core to the exosphere

The Crust

The crust is the outermost layer of the Earth.  This layer is thinner than the other layers and it is about 5 kilometers to 70 kilometers thick.

We live on what is called the continental crust which is part of the layer of the Earth.  The continental crust is made up of different rocks but mostly of silica and alumina.  The silica and alumina of the Earth’s Crust are called “sial.”

The crust is the layer of the Earth that people live on.  The crust also has the sea, soil, mountains, oceans, and more.  The crust is around 305 miles thick in the ocean.


It is important to understand that the lithosphere is the crust and part of the mantle.  The lithosphere is divided into tectonic plates or plates that float on top of the mantle.

These plates move and hit into each other and the plates sometimes go underneath each other or slide on top of each other.  These plates are called tectonic plates.

There are around 10-20 different plates that are all moving at different times and speeds on the Earth.  When these plates move, it can cause different things to happen such as:

  • Earthquakes
  • Tsunamis
  • Volcanic Activity
  • Building Mountains

The fastest-moving plate is the Cocos plate and it moves around eight inches each year.

The slowest-moving plate is the Eurasian plate which only moves less than an inch each year.

How Much of the Earth is the Earth’s Crust?

The crust of the Earth is the outermost layer of the planet.  The crust only makes up around 1% of the whole Earth.  Each layer is different and has different types of rocks and that is what makes them different form each other.

The thickness of the Earth's crust (km)

Continental Crust

The Continental Crust is part of the Earth’s crust.  This area is part of the crust that is covered by the land that we walk on.  The Continental Crust is the continents that make up our world.

The Continental Crust is made mostly of granite and that makes it a lighter color than other parts of the Earth.  On top of the granite is more rock called sedimentary rock.  Sedimentary rock is rock that is made up of parts of dead plants and dead animals that have begun to decay.

The Continental Crust is also made up of:

  • Metamorphic Rocks
  • Sedimentary Rocks
  • Granite
  • Sialic Rock

The Continental Crust is less thick than the Oceanic Crust even though it is much thicker than the Oceanic Crust.

The Continental Crust is what forms our continents and the continental shelf.

Continental Shelf

The Continental Shelf is part of the continents that are found under the water.  This was made when there were ice ages.

Each continent is part of the sea and is like an island.  Most of the island is above the water and this is why most of the continent is land that we live and walk on.  In the continental shelf part of the continent though, that part is underwater and can go very deep under the water.

Some areas of the continents have seas that are found inside of the continent.  These seas that are found in the continental shelf have the most sea life and the most nutrients.  Some of the sea life and nutrients in the continental seas include:

  • Plankton
  • Algae
  • Cyanobacteria
  • Iron

Oceanic Crust

Part of the crust that is under the ocean is called the Oceanic Crust.  This area is made up of lava that is made of basalt.  This lava flows underneath the ocean and has happened because of all of the volcanoes that have erupted for years and years.

Oceanic crust is a very heavy material and is very dark or black in color.

It is made up of different metals such as:

  • Silicon
  • Magnesium
  • Aluminum
  • Iron
  • Oxygen

The Oceanic Crust is around 8 kilometers thick.

Different types of lithosphere

Rocks of the Earth’s Crust

The Earth’s Crust is made up of many different kinds of rocks and metals.  Some of the rocks include:

  • Basaltic Layer-The basaltic layer is the layer of rocks that are part of the Oceanic Crust.  These rocks help to make the seabed floor.
  • Igneous Rocks-The igneous rocks are rocks that are made from magma that was flowing and then cooled and got hard.  When the magma got hard, it hardened inside of the Earth and became solid.
  • Sedimentary Rocks- The sedimentary rocks help to form part of the Earth’s crust.  These rocks are made from animals and plants that have died and begun to decay.

Earths Crust Facts for Kids:

  • Its made from basalt rock
  • It is around 25 miles thick
  • Made of granite rock
  • The only layer that can be drilled to be explored.
  • In the mountain areas, the crust is thicker than other areas.  The mountain areas can get up to 70 kilometers deep.
  • The Continental Crust and the Oceanic Crust are connected to the mantle.
  • When the Continental Crust and the Oceanic Crust connect to the mantle, this formed the Lithosphere.
  • The Lithosphere is a solid layer.
  • Under the Lithosphere is part of the mantle that is always flowing and moving.  When the mantle moves, it can cause things like earthquakes to happen.
  • The Ocean Floor is deeper than the land because the continents float on the mantle just like ice on an ocean.
  • The Earth’s crust is very hard because of all of the rocks and minerals that it is made up of.
  • The Oceanic Crust is around 3-5 miles thick.
  • The Continental Crust is around 25 miles thick.
  • The Earth’s crust can get up to 752 degrees Fahrenheit.
  • The Earth’s crust is the coolest layer of all of the Earth’s layers.
  • Oxygen is the most abundant chemical of the Earth’s Crust.
  • Scientists measure the movement of plates using satellites.
  • The crust is made up of eight different chemical elements.
  • Scientists drilled 7.5 miles into the crust of the Earth.

What Did You Learn?

  • What is the Earth’s Crust?  The Earth’s crust is the layer of the Earth that we live on.  The crust is the place where we walk and live.
  • What part of the Earth’s crust has the continents?  The Continental crust is the area of the Earth’s crust that has the continents.
  • What are plate tectonics?  Plate tectonics are how our continents move and slide under each other and bump into each other.  Plate tectonics are what causes there to be things such as earthquakes and tsunamis.
  • What part of the Earth’s crust is the ocean?  The oceanic crust is the part of the Earth’s crust that has the oceans in it.
  • What is the deepest part of the Earth’s crust?  The deepest part of the Earth’s crust is the areas that have mountains.