Rocks

Question 1

How can rocks differ?

Answer 1

Rocks can differ in colour, texture, hardness and mineral content.

Question 2

What are the three rock groups?

Answer 2

Igneous, Sedimentary, metamorphic

Question 3

How are igneous rocks formed? Give examples

Answer 3

They are formed from the magma in the mantle below the crust of the earth. It begins to cool very slowly (intrusive igneous). The magma that reaches the surface flows outwards, and once it hits the open air it begins to cool and harden quickly and form extrusive igneous rock.
Examples are granite and basalt

Question 4

How are sedimentary rocks formed? Give examples

Answer 4

They make up 3/4 of the rocks at the earth’s surface. They are made up of sediments of other rocks and the remains of dead plants and animals, which over time formed layers/strata, becoming compressed and cemented together to form rock.
examples are sandstone and limestone

Question 5

How are metamorphic rocks formed? Give examples

Answer 5

metamorphic rocks are formed when igneous or sedimentary rocks are put under great pressure or heat. This changes the rock into a new, harder rock.
Examples are marble and quartzite

Question 6

What is the most common rock type in Ireland?

Answer 6

Limestone

Question 7

How is granite formed? What rock group is it? Example of a source

Answer 7

Granite is an intrusive igneous rock. As it cooled very slowly over millions of years, the minerals in the magma formed very large crystals. It is multi-coloured. Fireplaces, countertops.
e.g. the Dublin-Wicklow and Mourne Mountains.

Question 8

How is basalt formed? What rock group is it? Example of a source

Answer 8

It is an extrusive igneous rock. It cools very quickly when lava reaches the surface. basalt has very small crystals. It is grey to black in colour. It can be used in road building.
E.g. The giant’s causeway in Antrim.

Question 9

How is sandstone formed? What rock group is it? Example of a source

Answer 9

When large amounts of sand were worn away from the earth’s crust, this sand was carried by the wind/rivers and was deposited on the beds of lakes/seafloor. The grains of sand built up and the deposits became compressed and cemented together.
It is typically red in colour It can be used to make tile and monuments.
e.g. Macgillicuddy’s reeks in Kerry

Question 10

How is limestone formed? What rock group is it? Example of a source

Answer 10

When the remains of dead sea creatures, shells and fish bones pile up on the seabed. Over millions of years, they become compressed and cemented together, forming strata due to great pressure. Some remains are preserved in rocks as fossils.
Limestone is permeable and soluble.
used as bases for buildings.
e.g. The Burren, co. Clare

Question 11

How is marble formed? What rock group is it? Example of a source

Answer 11

It is formed when limestone is put under great heat and pressure. In its pure form, marble is white, but it can also be green, red or black. It has a hard texture. It is used in making headstones, fireplaces and tiles.
e.g. Green marble in Connemara, white marble Rathlin islands

Question 12

How is quartzite formed? What rock group is it? Example of a source

Answer 12

It is formed when sandstone is put under great heat and pressure. This is usually during periods of folding when sandstone comes in contact with magma within the crust. It is grey or white in colour and is extremely hard in texture. It is used in watches, glass and in the surfacing of roads.
e.g. sugarloaf in county Wicklow and croagh Patrick in mayo.

Question 13

What do rocks provide humans with?

Answer 13

Oil, gas and turf can be used as heat and energy sources.
Gold, diamonds, metals and precious stones are used in jewellery.
Gravel, stone and sand are used as building materials.
Metal ores such as copper and lead are used in pipes and batteries.

Question 14

How are natural resources extracted from the earth?

Answer 14

Drilling, quarrying and shaft mining

Question 15

What is drilling? (environmental and economic impacts)

Answer 15

This is the process of boring down into the earth’s crust to extract oil or gas.

environmental impacts:
Oil spills can cause damage to the local environment, they can destroy natural plant and animal life in the area of the spill.
Animals can ingest the oil and it can cover their bodies, resulting in damage to the animal or death.

economic impacts:
Corrib oil has the potential to provide up to 60% of Ireland’s gas needs and is expected to supply fuel for up to 20 years.

Question 16

What is quarrying? (environmental and economic impacts)

Answer 16

This is the process of removing rock, sand, gravel or minerals from the ground.
Also known as open-cast mining, quarrying happens at or near the surface of the earth.

Environmental impacts:
Large quantities of dust are created, which can cause air pollution. It results in noise pollution for those living close to a quarry.

Economic impacts: Irish quarries produce about 35 million tonnes of produce annually. It generates over €1 billion for the Irish economy.

Question 17

What is shaft mining? (environmental and economic impacts)

Answer 17

This is the process of drilling vertically into the earth to gain access to minerals beneath the surface.

Environmental impacts:
Underground mining allows companies to dig for coal, lead or zinc deeper in the ground. Large quantities of earth and rock are brought up to the surface. Large amounts of dust are created. Dust particles can cause many health problems for people who breathe them in.