Rocks
Igneous Rocks
Granite
Granite is a hard, coarse, multi-coloured rock.
It contains feldspar and crystals of mica and quartz
It is formed when magma cools underneath the earth's crust
The magma cooled slowly and so allowed the crystals to form
It is found in the Wicklow and Mourne mountains
Basalt
Basalt is a heavy, black rock
It is formed when magma cools on the earths surface
It cooled too rapidly for any crystals to form
It is found int the Antrim Plateau and at the Giant's Causeway
Sedimentary Rocks
Sandstone
It is coarse and brown/red in colour
It is formed when large amounts of sand are carried away by rivers or wind
This sand is deposited on the beds of seas and lakes
The grains are gradually compressed and cemented together by the pressure and weight of the sea
The Macgillicuddy's Reeks, Comeragh and other mountains in Munster are mostly made of sandstone
Limestone
Limestone is made from the bones of dead fish and other sea creatures
Sandstone is a building material
When these creatures died their skeletons piled up on the bottom of the sea
The skeletons were crushed by the weight of more and more deposits
They were cemented together by the seawater and slowly formed into solid rock
Limestone is Ireland's most common rock
It is naturally laid out in horizontal layers called strata. The spaces between the layers are called bedding planes
The vertical cracks you see are called joints
Limestone is permeable, which means that water can pass through it
Limestone is used in manufacturing cement and steel and is used to make public buildings and to surface roads
Farmers use ground-up limestone as soil conditioner
Metamorphic Rocks
Quartzite
It is a light-coloured, hard rock
It can be white, grey, pink and red in colour
It is used to surface roads
It is found all over Ireland
It is found at the tops of hills and mountains, such as Errigal (Co.Donegal) and the Hill of Howth (Co.Dublin)
Quartzite is formed when sandstone is put under great heat or pressure
Marble
Marble is formed when limestone is put under great heat or pressure
It is a beautiful, hard, rock
It is used to make headstones, fireplaces and ornaments
It can be white (Rathlin Island), green (Connemara), red (Cork) or black (Kilkenny)
Quarries
Rocks which are used as building materials are usually taken from Quarries
Quarrying is the most common way of extracting rocks in Ireland
Pros
Cheap
Less dangerous than shaft mining
Cons
Can create dust which can pollute the air
Leave ugly scars on the Earth's surface
Trucks driving to and from Quarries can create traffic on nearby roads