Greetings, Emmet here, and it's time to rock.
There are three main types of rock and what makes them all different is how they were formed.
Sedimentary rocks, like sandstone and chalk, are made from layers of broken up bits of other rocks and the remains of animals and plants.
Over time these are squashed together to form rock.
But watch out, 'cause some can crumble easily.
Oops!
Then you've got metamorphic rocks.
These were changed by intense heat and pressure deep underground.
Metamorphic rocks include slate for roof tiles and marble for statues.
Hmm. That's better.
And finally we have igneous rocks like the hard granite used in building and paving.
These are made when molten rock, or magma, cools down.
This can happen slowly underground or quickly when it erupts from a volcano!
Ha ha ha! Man! Geology rocks!
Properties and uses
Different types of rocks have different properties.
Some rocks are harder than others. For example, granite is a very hard rock. This makes it a good material for building as it doesn’t wear away easily.
Marble is another hard rock. It has an attractive texture and colour and it can be cut and polished. Because of this, it is used to make floor tiles and wall tiles. Some statues are made from marble too.
Chalk is a soft rock and wears away easily. This makes it ideal for making chalk sticks to write on blackboards.
Some rocks, such as sandstone or chalk, let water soak through them. They are called permeable rocks.
Other rocks, such as slate, do not let water soak through them. They are called impermeable rocks. Slate also splits easily into thin sheets. This makes it ideal for making roof tiles.
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