Rocks

• Rock is the hard material that makes up the earth’s crust.

• Rock is made up of various minerals that are held together by a natural cement.

• There are three groups of rocks.

Rock Groups

• Igneous (Latin word for fire)

• Sedimentary (made up of sediments)

• Metamorphic (changed from heat or pressure)

Igneous Rocks

• Formed from volcanic activity.• Molten magma cooled• Two most common igneous rocks are

GRANITE and BASALT.• Granite is fromed when the magma cools in

the earth’s surface.• Basalt is formed when lava cools on the

earth’s surface.

granite

GRANITE MOUNTAIN

HOW WAS GRANITE FORMED?

• GRANITE WAS FORMED WHEN MAGMA FORCED ITS WAY INTO THE CRUST.

• IT COOLED VERY SLOWLY OVER MILLIONS OF YEARS ALLOWING LARGE CRYSTALS TO FORM ON IT

• IT VARIES IN COLOUR FROM GREY OR BLACK TO PINK IN COLOUR

• IT IS ROUGH AND HARD TO TOUCH

• WE USE IF FOR:

• BUILDINGS, MONUMENTS, FIREPLACES AND HEADSTONES

• WE CAN FIND IT IN THE MOURNE AND WICKLOW MOUNTAINS

BASALT ROCK

GIANTS CAUSEWAY COUNTY ANTRIM

HOW WAS BASALT FORMED?Basalt was formed when lava cooled very quickly (it hits the cold air) and

solidified.

• It has tiny crystals in it but these cannot be seen by the naked eye. These crystals are tiny because the rock cooled so fast.

• Basalt is smooth to touch and quite hard. It is waterproof

• It varies in colour from black to grey

• It can be found in the Giants Causeway in Antrim

• It is used in road surfacing

Sedimentary Rocks

• Formed from the sediments (remains) of other rocks, plants and animals that gathered at the bottom of rivers, seas and lakes

• Over time, they were compressed and cemented to form rocks.

• The two most common sedimentary rocks are LIMESTONE AND SANDSTONE.

LIMESTONE

LIMESTONE WITH FOSSILS

CHALK=PURE LIMESTONE

HOW WAS LIMESTONE FORMED?

• Limestone was formed on the beds of shallow rivers, seas when the skeletons of sea creatures, fish and shells collected there over millions of years

• The weight of the overlying sea compressed and cemented the skeletons into Limestone

• We can still see the tiny skeletons preserved in rocks today

What does Limestone look like?

It varies in colour from white to dark greyIt is a smooth, medium hard rockIt is permeable(allows water to pass through

it) and it is not waterproof.Rainwater will dissolve limestone

Limestone is used to make cement Farmers use limestone to improve the soils

fertility

Sandstone

How was sandstone formed?

• Sandstone was formed when large amounts of sand were worn away from the surface of the earth.

• Wind and rivers transported and deposited the sand on the beds of lakes and rivers

• Over millions of years this built up into sandstone

So what does it look like?

• It is rough to touch and medium hard

• It is not waterproof (water can pass through it). This means it is permeable. Do not remember!

• It varies in colour from brown to red and is used as building materials. It is also used for paving slabs in driveways

• It is found in the mountains of munster- magillicuddy reeks, the galtees and the Comeraghs

Metamorphic Rocks

• Formed from rocks that already exist.

• Igneous and sedimentary rocks are changed into new, harder rocks by great heat or pressure.

• The most common examples are QUARTZITE, SCHIST and MARBLE.

Quartzite (sandstone = quartzite)

• Metamorphic rock• Formed from sandstone.• Extremely hard and varies from white to

grey.• Used in road chippings and watches. • Often forms part of the peaks of Irish

mountains such as the Sugar Loaf in Co. Wicklow and Croagh Patrick in Co. Mayo.

Marblelimestone = marble

• When magma forces its way upwards into a body of limestone, it puts it under great heat and pressure.

• This changes it into Marble

• Marble is white but can be red or green

• It is used in fireplaces, kitchens, gravestones and ornaments

• We can find it in Cork and Connemara

marble

Marble

Homework from workbook page 9

• 1. name the 3 rock groups: Sedimentary, igneous and metamorphic rock

• (b) How are they classified? Rocks are classified according to their colour, mineral content, hardness and texture

• 2. identify one type of igneous rock

• Rock type: Basalt

• Description: dark grey to black, smooth to touch and quite hard

• How formed: it was formed when lava cooled very quickly outside the volcano.

• Location in Ireland: Giants Causeway-Antrim

• Rock type: Granite

• How was it formed: when molten magma made its way up towards the crust, it cooled very slowly to form granite.

• Description: black or grey to pink. It is rough and hard to touch

• Location in Ireland: Co Wicklow

Identify one type of sedimentary rock…either sandstone or limestone

• Rock type: limestone

• How formed: it was formed from the skeletons of small sea creatures that collected at the bottom of rivers and lakes over millions of years. They were compacted together with the weight of the water to form Limestone

• Description: white to grey. It is not waterproof

• Location in ireland: Burren- Co Clare

• Benefit to people: used as fertiliser, in buildings and in monuments

Identify one type of metamorphic rock…marble or quartzite

• Rock type: marble

• Description: white in colour but can be green or pink. It contains crystals

• How formed: when magma forced its way into the crust, it met with limestone and because of the great heat and pressure, it changed the limestone into Marble

• Uses: headstones, fireplaces and ornaments

Resources from the earth• What are Natural Resources? Something that

occurs in nature and is of value to people• Natural resources include 1. Coal: formed from dead plants. Found in coal fields. Used for heating

2. Gas: Found in oil fields. Used for heating, cooking

3. Oil: formed from dead plant and animals. Found under trapped under rocks. Used for Paraffin, petrol, diesel. By-products used in fertiliser, medicine, plastic, soap and perfume

4.Uranium (used in metal, steel, atomic bombs)

Copper, lead, zinc, diamonds, gold, silver Natural resources = “use it – you lose it”

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Extracting Resources• Three ways of extracting resources:

• Mining = when rocks/mineral are near the surface of earth

• Quarrying = for rocks/minerals close to surface of earth

• Drilling= when oil/gas is underground

• Shaft Mining – Takes place underground with tunnels leading down to the mine

• Open Cast mining – Takes place on the surface. Used for mining Coal

• Quarrying – removes rocks such as limestone for use in building

• Drilling – Used for extracting Oil

Disadvantages of extracting natural resources

Look at the diagram on page 23 of your books •Open Cast Mining?

•Shaft Mining?

•Drilling?