Rocks

Question 1

Rocks

Answer 1

Hard material that forms the Earth’s crust
• They are solid, occur naturally and are made up of one or
more minerals that have been compressed or cemented
together
• They differ in their mineral content, colour, hardness and
texture
• They are divided into 3 groups according to how they are
formed: igneous, sedimentary and metamorphi

Question 2

Igneous

Answer 2

Formed from volcanic activity
• Volcanic material cools down and
solidifies either within the crust or on
the surface
• Intrusive rocks formed from material
that cooled inside the crust
• Extrusive rocks formed from material
that cooled on the surface
• Eg Basalt and Granite

Question 3

Granite

Answer 3

• Intrusive rock
• Formed when molten magma forced its way into
the crust
• Cooled very slowly over millions of years and
allowed large crystals to form
• These crystals include quartz
• It came to the surface when the overlying rocks
were worn away
• They are black, grey and pink in colour
• Found in Wicklow mountains and Mourne
Mountains

Question 4

Basalt

Answer 4

• Extrusive rock
• Formed when the lava spread across the Earth’s
surface
• The lava cooled and solidified quickly as it was
exposed to the air
• Basalt has tiny crystals that can’t be seen by the
naked eye
• Colour varies from dark grey to black
• Found in the Giant’s Causeway in the Derry –
Antrim Plateau where the lava cooled and
shrank and cracked to form 6 sided colu

Question 5

Sedimentary

Answer 5

These rocks are formed from
the remains of other rocks,
plant life and animal life
• They are deposited on the beds
of seas and lakes aswell as on
land
• They have been compressed
and cemented together
• Eg are Limestone and
Sandstone

Question 6

Limestone

Answer 6

• Formed on the beds of shallow warm seas from skeletons of sea creatures, fish and shells
• These pile up over millions of years and have been compressed and cemented together
• Some of these remains have been preserved in the rocks as fossils
• Limestone is white or grey in colour
• It is permeable and allows water to pass through it
• It is laid down in strata or layers
• Found in the Burren and the Central Plain of Ireland

Question 7

Sandstone

Answer 7

Large amounts of sand were worn away from the Earth’s surface
and transported by wind and rivers
• The sand was then deposited on the beds of lakes and seas as well
as in deserts
• Deposits built up and were compressed and cemented to form
sandstone
• Can vary in colour from brown to red
• Found in the mountains of Munster eg the Galtees, the Comeraghs
and the Macgillycuddy Reeks
Sandstone
• Found in mountains of Munster

Question 8

Metamorphic Rock

Answer 8

Igneous or sedimentary rocks come into contact with heat
or pressure
• They change in shape and form
• Eg Marble and Quartzite

Question 9

Marble

Answer 9

Molten magma forces it’s way into a body of limestone and when
the rock exposed to great heat and pressure it converts to marble
• Pure marble is white but the presence of other minerals and change
the colour to red, black or green
• It is a hard rock that contains crystals
• It can be cut easily and polished
• Rathlin Island – white, Connemara- green , Cork – red and Kilkenny –
black ( this is a limestone)

Question 10

Quartzite

Answer 10

Sandstone originally
• Came into contact with magma deep in the crust usually during
periods of folding.
• Put under intense pressure and exposed to heat
• The grains of quartz are packed tightly together
• Varies from grey to white
• Hard rock and forms a cap on many mountains eg Croagh Patrick,
Mount Errigal, Sugarl