Transcript Rocks
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 grey It is a smooth, medium hard rock It 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 munstermagillicuddy 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. Marble limestone = 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” 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 08/04/2016 28 Disadvantages of extracting natural resources Look at the diagram on page 23 of your books • Open Cast Mining? • Shaft Mining? • Drilling?