What are the Different Types of Rock?

*guitar noise with heavy distortion*

Ahem — ever find yourself getting in a muddle over your mudstones and your marbles? If you’re a KS2 teacher or parent in need of a refresher on what’s what with sedimentary, igneous and metamorphic rocks you’ve come to the right place. Grab your pick-axe and follow me…
 

What is sedimentary rock?

Sedimentary rock is made of layers of sediment that build up over thousands of years at the bottom of the sea or in the bend of a river. Under the weight of more and more sediment, these layers are compressed into solid sedimentary rock. You can often see the neat layers in the final product — just like a well-made cake.

If you’re looking for fossils, sedimentary rock is your best bet. The remains of plants and animals can be preserved within the layers of sediment — this might be their hard bony parts, or sometimes even their footprints. The processes that form other types of rock are less gentle and don’t lend themselves to preserving much.
 

What is igneous rock?

Igneous rocks are made from cooled molten rock (known as magma). When magma reaches the surface of the Earth in a flow of molten hot lava, it cools and solidifies into rock in contact with the air (or water, if it comes out under the sea).

The slower the magma cools, the bigger the crystals that form within the rock — igneous rocks with the biggest crystals come from magma that cooled deep within the Earth’s surface.
 

What is metamorphic rock?

The key ingredients of metamorphic rocks are heat and pressure — well those and whatever other rock is at hand. Under heat and pressure, the original rock is changed by chemical reactions and the rearrangement of its minerals (sounds painful). It does not melt completely — if it did the final product would be igneous, not metamorphic rock.

Any type of rock (sedimentary, igneous or existing metamorphic rock) can undergo metamorphosis to become a new, sometimes shiny, metamorphic rock. You may see sediment layers and even fossils in metamorphic rocks, but they’ll probably be very distorted.

What is progressive rock?

Progressive rock is a type of rock characterised by its skilful compositions, experimental sounds and strong concepts. Rather than sticking to the rules of regular pop or rock, progressive rock incorporates elements of, and progresses toward the complexity of, classical or jazz music. It was popular in the 1970s with bands like Pink Floyd becoming household names.
 

Key Stage 2 resources on different types of rocks

Between a rock and a hard place when it comes to finding exciting ways of teaching about rocks? Don’t despair, we’ve got the solution:

• Our Rocks and Properties of Rocks Powerpoints (Year 3) are rock-solid ways of teaching the different types of rock and how to identify their properties.

• Have children take on the role of a rock seller with the Rocking Leaflet (Year 3). Choosing from a set of sedimentary, igneous and metamorphic rocks they must create a leaflet to advertise their chosen rock.

• Or for a crafty cross-curricular link, why not get creative with this Crafting with Clay (Years 3-4) Worksheet. Believe it or not, the result of firing clay in a kiln is your very own metamorphic rock.