Igneous Rocks for Kids
Do you know what igneous rocks are?
Read on, and we’ll tell you everything you need to know about them.
Perhaps you’ll be the next Geography superstar!
How is Igneous Rock Formed?
Magma (lava) comes out onto the surface of the Earth from volcanoes.
We get Igneous rock when magma cools down and becomes a solid.
The rock can form either above ground or below the surface.
Above the ground – magma cools down quickly and we get rock such as Tuff and Basalt.
Below the ground – magma cools down slowly and we get rock such as Granite
What types of Igneous Rocks are there?
Igneous Rock is categorized by how it actually formed.
As we know already, igneous rocks form when magma cools and hardens, this can happen underground or on the surface.
The exact location of where the rock forms, determines what type of igneous rock it is.
Get ready to find out about different igneous rocks.
Common types of igneous rocks are:
- Andesite
- Basalt
- Dacite
- Dolerite
- Diorite
- Gabbro
- Peridotite
- Nepheline
- Obsidian
- Scoria
- Tuff
- Volcanic bom
Extrusive Igneous Rocks
When magma rises up to the surface of the Earth and then hardens, we get something called extrusive igneous rock.
This type of rock is almost a bit glassy in texture as they form very, very quickly.
Types of extrusive igneous rocks are pumice and basalt.
Pumice is used in heaps of things like toothpaste, cement, and cosmetic products.
What a strange combination!
Basalt however is used in buildings and statues.
Sometimes extrusive rocks are called volcanic rocks as volcanoes are obviously very important in how they form.
Intrusive Igneous Rocks
Extrusive rocks are formed when magma rises to the surface of the Earth and hardens, which forms extrusive igneous rocks.
But with intrusive igneous rocks, they are formed when the magma cools and hardens below the Earth’s surface.
These rocks take a long, long time to form because of the way that they are made. They feel very grainy when you touch them.
Intrusive igneous rocks are granite and gabbro. Ever heard of gabbro? If not read on to find out.
Granite is used for making gravestones, statues and countertops too. Do you have a granite countertop at home? It’s very durable, which means it can take a lot of pressure and wears very well.
Gabbro is an interesting rock that you might like to dig around for! It’s often got lots of gold, chromium and silver in it. You could sell it make some pocket money!
Then there are things called Plutons and these are like bodies of intrusive rock that mostly have granite in them.
When intrusive rocks form huge bodies, like those found inside of mountains they are called batholiths.
Igneous Rock Facts for Kids
- Scientists have identified over 700 different types of igneous rocks.
- People who study rocks are called geologists.
- Scientists can tell the age of igneous rocks by using something called radiometric dating.
- They normally contain no fossils.
- Usually made of two or more minerals
- Basalt is an example of a basic extrusive igneous rock.
- Gabbro is an example of an intrusive igneous rock.
- When magma (lava) rises to the surface cools quickly, it forms extrusive igneous rock.
- When magma cools and hardens below the Earth’s surface, an intrusive igneous rock forms.
- Ninety-five percent of the Earth’s crust is made of igneous rock.
- The ocean floor is normally made out of basalt rock, which is hard and black, and an extrusive rock of course.
- The batholiths that we spoke about can be as large as about 97 km across.
The Giant’s Causeway
The Giant’s Causeway, in Ireland, was made from a lava flow that erupted over 55 million years ago.
The lava cooled, and as it did this it split and formed about 40,000 basalt pillars, which look like humongous stepping stones that reach out into the ocean.
So ace that next Geography test with all this cool information about igneous rocks!
You can do it!
