Unit 5E.1: Rocks and How We Use Them

Transcription

1 Unit 5E.1: Rocks and How We Use Them Looking at rocks Using rocks Weathering Soil Science skills: Observing Classifying By the end of this unit you should be able to: Compare different rocks and group them Realize we rocks based on their properties Know that: - The rock is the solid part of the Earth's crust. - Different rocks show different properties. - The causes of weathering.soils are formed from rocks. - Types, Characteristics and properties of different soil. 53

2 Looking at Rocks What do we walk on? Live in? Climb sometimes? Sit on sometimes? Rocks! Looking at Rocks Are all rocks the same? Are the rocks shown here the same? Can you describe how they are different? Classifying rocks: Getting ready: In this activity you will observe and classify Rocks according to their properties. 54

3 Materials you need: - 5 different rock samples labelled 1 to 5 - Hand lens - Dropper, Vinegar - Safety goggles - Paper plate - Paper towels, Beaker - Water, Glass plate Procedure: 1. Make a chart like the one shown at the end. 2. What colour or colours in each rock? 3. Can you see any grains? Are the grains very small or large? Record your observation under texture in your chart. 55

4 4. Rub each rock against other rocks and find out whether it easily marks other rocks or a concrete floor. The softer rocks leave marks on the harder ones! Write if it leaves a mark under rubbing 5. Using a hand lens, observe how many pores (small empty holes) you can see in the rock. Test by putting a few drops of water on it. If it allows water to go through it is porous. This is what we call porosity. 6. Caution: wear your safety goggles. Use the dropper to add a few drops of vinegar on each rock. 56

5 Record your observation: Rock sample Colour Texture Rubbing Porosity Bubbles when vinegar added 57

6 Where are rocks found? Look at the following pictures and discuss where the rocks can be found? Also think about why can we see some rocks and not others: 58

7 Rocks lie beneath all surfaces of the Earth: Why do you think these rocks are so smooth? 59

8 Earth and space Using Rocks How is this rock being used? Discuss with your partner? How did they make? Uses of rocks depend on their properties. Try and complete as much of the table below as possible, your teacher will help once you have tried yourself. Here is a clue to start you off... 60

9 Uses of rocks I have seen draw a picture if you like! What is the name of the Rock used Why is this rock used? 61

10 Rocks are traditionally used as building materials. Look at this house! It is made from natural rocks! People used to make such homes before. We now have the machinery to use rocks as we need make cement, bricks etc Look at the house below quite clever what do you think? Now, we use different rocks for different jobs depending on their properties.. 62

11 Examples: Limestone and sandstone are used as building blocks Slate is used for roofing tiles. Granite and marble are much harder than limestone and sandstone. They are used for statues and headstones. WRITE THE TYPE OF ROCK UNDERNEATH! 63

12 Research.. Find out about the following famous places, make posters and try and find different pictures to add to your poster, include information: How the different rocks are used? When it was built? What types of rocks etc. Clues: Egypt, (Aztec) Mexico, Yemen, Petra (Jordan) 64

13 Clay is used to make an important building material caked Cement. To learn more about the rocks and their uses, Study this table: Name of rock Properties Uses Limestone Hard and coloured Building blocks Quartz Attractive colours Jewellery 65

14 Slate Water proof Roofs and buildings Granite Hard Steps, floors Marble Attractive and can be polished Steps floors Chalk Breaks easily Writing Soapstone Soft and may feel soapy when touched Inlaid designs, statue, kitchen and for traditional carvings. 66

15 Do you know? The most rocks in Qatar are sedimentary, so they have many pores (high porosity) which make them good containers for petrol and natural gas. Key Idea: Rocks have different uses depending on their properties Key words: Stone Age Lime stone Quartz Slate Granite Marble Chalk Soapstone 67

16 Key questions: Fill these spaces using the following words: a) Steps b) Roofs c) Writing d) Statues Explain the following observations: a. Limestone and sandstone are good building materials because... b. Slate is good for roofing because.. c. Granite chips are good for road making because.. d. Stone carvers like using soapstone for their work. 68

17 Earth and space Soil: Where does soil come from? Let s first ask where did the sand come from? This is in Zikreet! The picture gives you a clue! You can make your own sand! Place a piece of white paper and rub the rock with your fingers! Weathering The surface of the Earth is always changing like in Zikreet. This may come as a surprise, as the rocks and hills look the same for years! This is because the process of changes happens very slowly. The rocks slowly break into smaller pieces we call it weathering. Weathering: is the breaking down of rocks into smaller and smaller pieces. 69

18 Causes of weathering: 1. Frost action: Most things contract when they freeze but not water. Water expands when it freezes into ice. Rain water seeps into tiny cracks in rocks. When the water freezes it expands. The ice presses against the sides of the cracks. The pressure is great. It can make cracks bigger. Activity: In this activity you are going to see how water changes volume when it freezes, and how rocks can be broken due to this. Completely fill a small glass jar (an old jam jar) with water and screw on the lid. Now place it in a clear plastic bag, tie the bag at the top and put it into the freezer. Leave it for 12 hours!. Do NOT remove it from the plastic bag. 70

19 Describe and explain what happened! Label this diagram and explain to your partner what is happening! What do the arrows mean? Temperature changes: Heat makes most things expand-get bigger. Cold makes most things contract-get smaller. In most places it is warmer during the day than at night. Heat expands rocks during the day. At night the rocks cool off and contract. The expanding and contracting happen over and over again. That strains the rocks. The strain makes them crack, a tiny bit at a time. 71

20 Animal activity: Animals do not break rocks a part by themselves. But some animals dig into the ground. Ants, worms, rodents etc. dig holes. The holes let in air and water. The air and water weather the rocks, breaking them into smaller pieces. 4. Wind: Wind is sometimes strong enough to break particles of sand from a rock. The sand may be carried by the wind. If the sand hits another rock it will break even more particles, causing the rock to wear away. 72

21 5. Water: a. When rain hits the rocks it breaks it into small pieces, you see the lines the water has made as it moves.. b. Around the world, moving water picks up and transports millions of tonnes of sediment every day, along rivers, coasts, and even in the deep oceans. 73

22 Do you know? The Mississippi river carries over 500 million tonnes of sediment to the sea each year!! Grains are worn smooth as the water carries them along. That s why beach sand is smoother than river sand. Key Ideas: - Weathering is the breaking down rocks into small pieces. - Temperature, frost, animals, wind and water, help to weather rocks. - Expand: to become bigger - Contract: to become smaller - Rocks are a solid part of the Earth. - Earth is a rock Key words: Weathering Frost Expand Contract Project: Make a poster for the causes of weathering showing pictures for each cause. Include, CLEAR TITLE, explain the different types of weathering using pictures and diagrams! Make it look nice, use big writing and don t forget your names!! 74

23 Key questions: Q1: What does weathering mean?. Q2: List three causes of weathering the rocks: Q3: Describe how weathering takes place by water. Q4: Explain why many stones found in streams and in the sea are smooth. 75

24 Earth and space Soil Now we know how big rocks get broken into smaller pieces and how these smaller pieces are moved about by water or wind. Soil is basically the collection of these small pieces! Have you ever played in a sandbox? Would you believe that all that sand was once big rock? Soil is formed from small pieces of rock Soil is of different types depending on the areas... What kind of soil is this? Write the type next to it! 76

25 Soil is produced when rocks are broken down into small pieces by weathering. The type of soil depends on the type of rock from which it was made. Soils from different rocks have different physical characteristics and properties. Investigating soil properties: 1. Examine with hand lens: Examine different soils under a magnifying glass look at particle size, colour, and texture and at any rotting organic matter. 77

26 particle size Soil (1) Soil (2) Soil (3) Colour texture rotting organic matter 2. Particle size: Activity: Use a sieve to separate some different soils. The soils should be dry and you should use the same sieve each time to keep it a fair test. My observation: 78

27 2. Absorption and flow of water: Activity: 1. Poke holes in the bottoms of three plastic containers. 2. Put different type of soil in each container. 3. Pour water into the soil 4. Collect for 1 min the water which comes through the container Soil Particles through the mesh Amount of water Results:... Most soils are one of three types: 1. Clay soil 2. Sandy soil 3. Humus soil 79

28 Clay holds water. Land with clay soil can be easily flooded. Water runs quickly through sandy soil, thus plants may not have enough water. Humus soil is a dark coloured soil that develops as dead plants and animals decay, when it can t decay any further it is called Humus. Activity: What is soil made of? Put a sample of each soil in a clear plastic drink bottle so that the bottle is about half full. Put water in the bottle until it is about three-quarters full. Put the top on and shake the bottle hard. Then put it down and wait for it to settle. Look at how it has settled. 80

29 Where are the stones? Where are the big particles of soil? Where is the fine (small pieces) soil? What does the water above the soil look like? Are there any bits that float? If so what are they? Draw a picture of the results and describes the main layers of the soil in the box. 81

30 Type of soil Sandy Clay Humus Colour of soil light Dark Little dark Size Large Small Medium Texture Rough Smooth Smooth & rough Time for water to Fast Slow Medium pass through Drawing the particles 82

31 What is good soil? Good soil is made through the combination of erosion by rivers and biological processes that puts humus into the soil. A good soil has: 1- humus which is important to hold water in the soil. 2- has quite large soil particles, a soil with fine particles does not drain well. 3- spaces for air, the plant roots and other living things in the soil need air. Key words: Soil Clay Loam Sandy Project: Go in a trip with your teacher and try to collect different types of soil, classify them into 1. Loam soil 2. Clay soil 3. Sandy soil Key Ideas: Soil is small pieces of rock. Soil is classified into 3 types: 1. Clay soil 2. Loam soil 3. Sandy soil Do you know? Earthworms burrow through the soil. As they move, they turn over soil better for farming. 83

32 Key questions: Q1: Which type of soil is the best for plants? Why? Q2: Compare between the three types of soil: Characteristic Sandy soil Loam soil Clay soil Color Texture Explain why water sinks slowly through soils that are made of fine particles but quickly through sandy soils that are made of larger particles. Explain why the valleys of the Nile and the Tigris and Euphrates are rich agricultural areas and explain the origins of the sand deserts in the Arabian Peninsula.. 84