Rocks

Igneous Rocks:

Are formed when hot, molten volcanic material cooled down and became solid.

Eg- Granite and basalt.

Sedimentary Rocks:

Are formed from the compressed remains (sediments of animals, plants or other rocks) 

Eg- Limestone and sandstone.

Metamorphic Rocks:

Were once igneous or sedimentary rocks which were changed by great heat or pressure.

Eg- Marble and quartzite.

Granite Rocks: 

• Granite is a hard, coarse, multi-coloured rock. 
• It contains pink or grey feldspar and crystals of mica quartz.
• It was formed when magma cooled deep within the earth's crust. 
• The magma cooled so slowly that large crystals had time to form.
• Granite is found in the Wicklow and Mourn mountains.

Basalt Rocks:

• Basalt is a heavy, black rock.
• It was formed when lava cooled on the earth's surface.
• The lava cooled to rapidly for any crystals to form.
• Basalt is found in the Antrim Plateau and at the Giants Causeway.

Sandstone Rocks:

• Sandstone is usually coarse and brown/red in colour.
• Its formed when large amounts of sand are worn from the earth's crust, carried away rivers or wind and deposited on the beds of seas or lakes.
• The sand grains are then very gradually compressed and cemented together to form rock.
• The macgillicuddy's reeks, Comeragh and other mountains of Munster are made up mostly of sandstone.

Limestone- Irelands most common rock. 

Origin 

• Limestone is made from the remains of fish and other sea creatures.
• As generations of these creatures died, there skeletons were piled up on the beds of shallow seas.
• The skeletons were crushed by the weight of later deposits and cemented together by the sea water until they form slowly into solid rock.

 Characteristics of limestone;

• Limestone is laid down in horizontal layers of strata. 
• The divisions between the layers are called bedding planes.
• Vertical cracks or joints also occur.
• It may contain fossils.
• It is permeable, which means that water can pass through it.
• It is easily weathered or worn away.
• The rain water that passes through it is weak carbonic acid which dissolves the calcium carbonate that makes up the limestone.

Uses of Limestone:

• Manufacturers use limestone to make cement for building. It also makes headstones.
• Builders use blocks of limestone to make public buildings. Limestone chippings are used to surface roads.
• Farmers use ground-up limestone as the soil conditioner.

Quarries:

• Rocks used as building materials are usually quarried directly from the earth's surface. 
• So are sand and gravel, which are used to make concrete and wall plaster. 
• Quarrying is the most common way of extracting rocks in Ireland.
• Its cheap and less dangerous than shaft mining.
• Quarrying sometimes creates dust that pollutes the air. 
• Quarrying also creates visual pollution by leaving ugly scars on the earth's surface.