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The Changing World

The Changing World

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The Changing World

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  1. The Changing World The Restless Earth

  2. The crust is made of about twelve plates. These are like big rafts floating on the semi-molten mantle. Convection currents within the mantle cause the plates to move. Although they only move about 2 cm/year this can have huge effects over long periods of time. Tectonic plates

  3. When two oceanic plates move apart molten rock rises to the surface. sea floor spreading oceanic plate magma rising Sea floor spreading

  4. On average, the plates only drift about 2cm/year. However 2cm multiplied by a million is a long way! Scientists think the continents were originally all together in a super-continent called Pangaea. Over millions of years they have drifted to their present positions on the floating tectonic plates. Pangaea Millions of years Continental Drift

  5. Continental Drift

  6. The theory is supported by several pieces of evidence. For example, if we consider Africa and South America there is: The “jig-saw fit” The similarities in the rock layers from Africa and South America. Similarities in the type and age of fossils. Evidence of related species that definitely did not swim the Atlantic Ocean! Jig Saw fit Similar rocks and fossils Evidence for Continental Drift

  7. How do convection currents actually work? Place potassium permanganate crystals at bottom of beaker of water Start to heat water with bunsen Diagram in book of what happens How does it work? Heat

  8. Plate boundaries

  9. Constructive plate boundary – new ocean floor is created Destructive plate boundary – oceanic plates slide under continental plates – subduction Conservative plate boundary – plates slide past each other - Earthquakes What happens when plates meet

  10. volcanoes result from the rising magma (melted oceanic plate) volcano oceanic plate magma rising continental plate Effects at Plate Boundaries When a continental plate and an oceanic plate meet, the effects include: • plates juddering past each other producing earthquakes • the continental plate buckles upwards whilst the oceanic plate subducts (goes underground)

  11. Find the words and write a sentence about how each one has something to do with plate tectonics. Drift Earthquake Fossil Jigsaw Magma Pangaea Plates Subduct Volcano Activity

  12. Rocks

  13. There are three main types of rocks: Igneous - formed when molten rock cools. Sedimentary – formed by the “cementing together” of small grains of sediment. Metamorphic – rocks changed by the effect of heat and pressure. All of these are involved in a continuous flow of rock from the surface underground only to emerge again later as part of the on-going rock cycle. Types of rocks

  14. These are rocks formed by the cooling of molten rock (magma.) volcano magma Igneous rocks Magma cools and solidifies forming igneous rocks.

  15. Igneous rocks divide into two main groups: Intrusive igneous Extrusive igneous. • Intrusive igneous rocks, like granite, are formed when magma solidifies within the ground. • Extrusive igneous rocks, like basalt, are formed when magma solidifies above the ground. Types of igneous rocks

  16. The more slowly a rock changes from liquid to solid the bigger the crystals grow. • Intrusive igneous rocks that cool really slowly can have very big crystals. Extrusive igneous rocks that cool really quickly can have a glassy appearance. Igneous rocks and crystal size Intrusive igneous rocks, like granite, usually have clearly visible crystals. Extrusive igneous rocks, like basalt, have crystals that are usually small.

  17. Surface rocks seem to be gradually reduced in size by weathering processes. Chemical weathering is when chemicals, such as those in acid rain, ‘eat’ away certain rocks. Physical weathering is to do with the rocks being broken down by the action of wind, rain and sun. For example, during the freezing and thawing of water in the cracks of rocks, the expansion of water makes the rocks splinter. The small broken fragments wash into rivers and, eventually, reach the sea where they settle as sediment. Chemical and Physical Weathering

  18. Sedimentary Rocks are rocks formed when particles of sediment build up and are “cemented together” by the effect of pressure and minerals. Rocks are broken up by the action of weather sea Sedimentary rocks Sedimentary rocks Fragments washed to the sea

  19. Sedimentary Rocks tend to have visible grains of sediment. Sometimes they contain fossils. They are usually softer than igneous rocks. Examples of sedimentary rocks are sandstone and mudstone. Getting older Sedimentary rocks Sandstone is formed from the cementing together of grains of sand.

  20. Metamorphic rocks are formed by the effect of heat and pressure on existing rocks. This can greatly affect the hardness, texture or layer patterns of the rocks. Pressure from surface rocks metamorphic rock forming here Magma heat Metamorphic rocks

  21. Marble, slate and schist are metamorphic. Limestone is a rock often formed from the sediment of shells. Temperature and pressure cause the rock to reform as small crystals that are much harder. It is used as a hard and decorative stone in buildings, sculptures etc. Slate is formed when pressure squeezes mudstone into plate like grey sheets. It is used in roofing. Schist and mica are formed when mudstone is subjected to very high temperatures as well as pressure. Again they contain layers which is typical of many (not all) metamorphic rocks. Metamorphic rocks

  22. Match the rock with the correct description. Give an example of this type of rock. Activity

  23. The rock cycle

  24. Crack the code! What should this really say? (Giant hewer)leads to fragments collecting in the sea and forming (am seen dirty)rocks such aschalk, (sum to end)and(and so nest). Heat and(perusers)can lead to(a chem import)rocks such as(stale)and(ambler). Some of these willmelt and eventually cool as they approach the surface to form (I ruin vets)(go in use)rocks such as (get rain). Activity Weathering sedimentary mudstone sandstone pressure metamorphic slate marble intrusive igneous granite

  25. What gases would have formed the original atmosphere around planet Earth? Hydrogen and helium Oxygen and nitrogen Methane and ammonia Carbon dioxide and water

  26. What gases form the majority of the present atmosphere around planet Earth? Hydrogen and helium Oxygen and nitrogen Methane and ammonia Carbon dioxide and water

  27. What gas protects us against dangerous UV radiation? Sulphur dioxide Nitrogen oxide Methane Ozone

  28. What gas is a major cause of the greenhouse effect? Sulphur dioxide Nitrogen oxide Carbon dioxide Chlorine dioxide

  29. What process increases atmospheric carbon dioxide levels? Photosynthesis Respiration Formation of Fossil fules Formation of carbonate rocks

  30. What layer of the Earth is around 50Km thick and high in silicon and oxygen? Inner core Outer core Mantle Crust

  31. What layer of the Earth is mostly molten iron and nickel? Inner core Outer core Mantle Crust

  32. What layer of the Earth is made of viscous semi-molten magma? Inner core Outer core Mantle Crust

  33. What type of rock is formed by solidification of molten magma? Igneous Metamorphic Sedimentary Fossilised

  34. What type of rock is formed by cementation of small particles of weathered rock? Igneous Metamorphic Sedimentary Fossilised

  35. What type of rock is formed by the effect of heat and pressure upon other rocks? Igneous Metamorphic Sedimentary Fossilised

  36. What type of rock is least likely to contain fossils? Igneous Metamorphic Sedimentary Fossilised

  37. What is the process where tectonic plates separate and magma creates new solid crust? Weathering Ageing Sea floor spreading Sedimentation

  38. What is the process where tectonic plates move gradually apart? Continental breakfast Continental drift The rock cycle Subduction

  39. Which of these is not evidence for continental drift theories? Similarities of fossils Similarities of rock layers Jig-saw fit of coastal shapes Similarities of climate