2021

INTERNATIONAL

SCHOOLS MOSAIC

COMPETITION

S T A R T E R P A C K

GEOLOGY OF THE UK

I N TRODUCT ION

Rocks are everywhere! Whether they are under the ground or

above the surface, large or small, you are never too far away

from a piece of rock.

As you begin to collect small pieces of rock for your school’s

mosaic, you will notice that many of them look very different in

colour and design.

So, to help you identify some of the rocks that you may find, we

have put together some information on the types of rock that

can be found within the UK.

GEOLOGY OF THE UK

ROCK TYPES

Basically, there are three different types of rock that make up the

UK; Igneous, Sedimentary and Metamorphic. But what do these

big words mean? Let’s take a look!

IGNEOUS

Believe it or not, Britain used to have active volcanoes that would

erupt lava, caused by nearby plate boundaries deep beneath the

surface. As soon as this lava reached the surface it would cool

very quickly and become solid to form basalt rock.

Other Igneous rocks are formed below the surface as hot magma

is cooled and the weight of the ground above squashes it into a

solid. This is known as an intrusive rock with examples being rocks

called granite and gabbro. These rocks find their way to the

surface as the rocks above are eroded or weathered away.

GEOLOGY OF THE UK

SED IMENTARY

When you have been on a sandy beach, have you ever taken a

close look at what makes up the sand itself? Well, sand is a

combination of very small particles of rock, shells and other

debris which has been carried there by either water or the wind.

This sand, also known as sediment, can be found at the bottom of

the sea and lakes, forming several layers over time.

As these layers of sediment build up, the ones that are further

down start to become squashed, or compressed, by the weight of

everything above it. This, along with an increase in heat, causes

sedimentary rocks to form in layers. When sand is compressed, it

forms sandstone.

It isn’t just sand that can be compressed into rock. The remains of

plants, animal and marine species can also be compressed to

form limestone and chalk. In fact, these types of rock can often

contain fossils.

ROCK TYPES

GEOLOGY OF THE UK

METAMORPH IC

Despite the name, this doesn’t mean that these rocks can change

their shape in the palm of your hand! But they have been

changed in both shape and form by intense heat and pressure.

They start out as either Igneous or Sedimentary rocks which begin

to crystallise when they are exposed to extreme heat and

pressure.

Having gone through these intense conditions and changes,

Metamorphic rocks are very hard compared to others. Some

examples of these rocks include slate, schist and marble.

ROCK TYPES

MINERALS

All of the above types of rock will also contain minerals, however

sometimes you will just find minerals by themselves. A mineral is a

natural substance that isn’t man-made and is inorganic (not

made by a living thing).

Many minerals have a crystal-like appearance with some being

almost transparent. Some examples of minerals include quartz,

calcite, gypsum and feldspar.

Depending on where you live in the UK, you may encounter a

wide variety of rocks. Certain areas feature more igneous rocks,

while others have a plentiful supply of sedimentary rocks. Either

way, you will find many different types as you search your garden

and the local countryside. To help you to try and identify what

type of rock you have found, we have put together an

identification sheet that provides more information on the more

common rocks that you will encounter.

ROCKS YOU M IGHT F IND

NA

ME

TY

PE

CO

LO

UR

GR

AIN

SIZ

EP

HO

TO

Igne

ous

Se

dim

enta

ry

Min

era

l

Min

era

l

Se

dim

enta

ry

Da

rk Fi

ne

or

Mix

ed

Ba

salt

Ca

lcit

e

Cha

lk

Co

ng

lom

era

te

Feld

spa

r

Lig

ht

Mix

ed

Lig

ht

Lig

ht

-

Fine

Mix

ed

-

NA

ME

TY

PE

CO

LO

UR

GR

AIN

SIZ

EP

HO

TO

Igne

ous

Me

tam

orp

hic

Min

era

l

Min

era

l

Se

dim

enta

ry

Lig

ht

C

oa

rse

Gra

nit

e

Gyp

sum

Lim

est

one

Ma

rble

Qua

rtz

Lig

ht

Lig

ht

Lig

ht

Whit

e

-

Fine

Co

ars

e

-

NA

ME

TY

PE

CO

LO

UR

GR

AIN

SIZ

EP

HO

TO

Se

dim

enta

ry

Me

tam

orp

hic

Me

tam

orp

hic

Se

dim

enta

ry

Lig

ht

C

oa

rse

Sa

nd

sto

ne

Schis

t

Sha

le

Sla

te

Mix

ed

Da

rk

Da

rk

Co

ars

e

Fine

Fine

ROCK MAP OF THE UK