1. In this presentation you will: explore the rock cycle explore the processes that change rocks and the structure of the Earth’s surface ClassAct SRS enabled.

2. In this presentation you will learn about the rock cycle. Next > You will explore the natural processes that are involved in the rock cycle and see how they can change the surface of the Earth. Rock Broken down Reformed

3. Next > I. The Rock Cycle A. Rocks are constantly being broken down, built up, and then broken down again by natural processes. This is known as the rock cycle. B. There are three main different types of rock. During the rock cycle these different rock types are slowly changed from one type into another. C. The rock cycle is a very slow process. It takes thousands of years for rocks to change form, and millions of years for the rock cycle to complete.

4. 1 How long does it take for the rock cycle to complete? Question A) Tens of years B) Hundreds of years C) Thousands of years D) Millions of years

5. Next > II. Different Types of Rock A. Sedimentary rocks form when layers of sediment (small rock pieces and dead matter) are laid down in lakes or seas and cemented together over millions of years. C. Metamorphic rocks form when heat and pressure is exerted on sedimentary or igneous rocks over long periods of time. B. Igneous rocks form from magma that is pushed up toward the surface of the Earth’s crust, and often out through volcanoes. Sedimentary Igneous Metamorphic

6. How many main rock types are there? Enter your answer and press Send. Question2

7. Next > III. Processes of the Rock Cycle A. Different processes are involved in the wearing down and building up of rocks. B. These processes are constantly at work, changing the surface of the Earth. C. You will see these processes on the following slides. Weathering of exposed rocks Erosion and transportation MeltingBurial, compression and cementation Heat and pressure Cooling below surface Cooling above surface Sedimentary Metamorphic Magma Deposition Extrusive igneous Uplift Intrusive igneous

8. Next > 1. Weathering a. Weathering weakens and breaks down exposed rocks on the surface of the Earth. It is caused by many different things, for example the Sun, acid rain, plants and animals.

9. Next > 2. Erosion a. Erosion wears down rocks through movement. Erosion is caused by the movement of rivers, ice, sea and wind.

10. Next > 3. Transportation a. Transportation moves the broken down bits of rock around the world. This is mostly done by wind and water.

11. Next > 4. Deposition a. Deposition lays down the sediment from the eroded rocks. This mostly occurs on the beds of lakes and seas.

12. Next > 5. Burial/Compression/Cementation a. The processes of burial, compression and cementation squeeze and compress the layers of sediment until they form sedimentary rock. Limestone is an example of sedimentary rock.

13. 6. Heat/Pressure a. As layers of sediment build up, the lower layers of sedimentary rock get heated and squashed. This slowly turns the rock into metamorphic rock. For example, marble is metamorphic rock that was once limestone. Next >

14. 7. Melting a. The intense heat under the Earth’s surface makes rock melt. Molten rock is known as magma. Magma sometimes rises to form volcanoes.

15. Next > 8. Cooling b. If magma solidifies above ground, like basalt, it is called extrusive igneous rock. a. As magma rises it cools and solidifies to form igneous rock. If magma solidifies underground, like granite, it is called intrusive igneous rock.

16. Next > 9. Exposure a. When any type of rock is exposed to the elements it is weathered and eroded again and the cycle continues. The amount of rock on the surface is always about the same, even though it is constantly being broken down.

17. Next > The Complete Rock Cycle Weathering of exposed rocks Erosion and transportation Melting Heat and pressure Cooling below surface Cooling above surface SedimentaryMetamorphic Magma Deposition Extrusive igneous Uplift Intrusive igneous Burial, compression and cementation

18. 3 Which of the following processes breaks down exposed rocks on the Earth's surface? Question A) Deposition B) Cementation C) Transportation D) Weathering

19. 4 Which of the following changes sedimentary rocks to metamorphic rocks? Question A) Burial, compression and cementation B) Cooling C) Exposure D) Heat and pressure

20. Summary After completing this presentation you should be able to: End > show knowledge and understanding of the rock cycle show knowledge and understanding of the processes that change rocks and the structure of the Earth’s surface

21. In this presentation you will: explore the movements of the plates that make up the Earth’s surface explore geological events caused by plate motion ClassAct SRS enabled.

22. A. The outer layer of the Earth is broken up into a number of different plates, which are constantly moving at a very slow speed. Next > B. The movements of the plates can dramatically change the Earth’s surface. Volcanic eruptions, earthquakes and mountain building all occur as a result of plate motion. C. In this presentation, you will explore causes and effects of plate motion. I. Plate Motion

23. Next > II. Continental Drift A. The idea that the Earth’s surface is made up of a number of constantly shifting plates was first proposed in the early 20 th century. C. A scientist named Alfred Wegener used this observation to put forward a theory that the continents had once been joined together. The continents were formed when the Earth’s surface split into a number of plates. They have then drifted to their current locations over millions of years. B. Many people had noticed that the coastlines of the continents appear to fit together like puzzle pieces. D. This became the theory of continental drift.

24. Next > G. Continental drift was disputed by scientists for many years. However, as more evidence was found, it became universally accepted. It has since been incorporated into the theory of plate tectonics, a wider theory of plate motion. E. Fossils of different species of plants and animals had been found across different continents. This supported Wegener’s theory that the continents had once been joined together. F. Areas of folded and deformed rock also suggested that movements of the crust had occurred in the past. Cynognathus – a land reptile Glossopteris – a fern Mesosaurus – a freshwater reptile Lystrosaurus – a land reptile Fossil Evidence

25. Next > III. Composition of the Earth B. The crust is the outer layer of the Earth, made from solid rock. It is much thinner than the lower layers of the Earth. The crust has two main parts: 1. Continental crust – this forms the continents. Its thickness varies from 20 km to 80 km. 2. Oceanic crust – the thin crust under the oceans. It is around 10 km thick. A. To understand how and why the plates move, you first need an understanding of the structure of the Earth. The Earth is made up of a number of different layers, each of which has different characteristics. Crust

26. Next > C. The mantle is underneath the crust. It is made of rock although, due to intense heat, it behaves like an extremely thick liquid. The mantle moves for reasons which you will explore in following slides. The movement is so slow that its motion would only be noticeable over hundreds of years. D. The mantle has two parts: 1. Upper mantle – the more solid portion of the mantle. At the top, the temperature is around 1000 °C. The upper mantle and the crust form the lithosphere – the solid outer layers of the Earth. 2. Lower mantle – the less solid portion of the mantle. It extends 2900 km below the surface of the Earth. At the bottom, the temperature is around 3700 °C. Mantle

27. Next > E. Below the mantle is the outer core. It is mostly made of iron but, because of the extremely high temperatures, the iron has melted and become liquid. F. A solid inner core is suspended in the outer core. Although the temperatures at the core are around 4300 °C, the pressure is so great that the iron stays solid. G. The lower mantle, outer core and inner core make up the semi-liquid asthenosphere. Outer core Inner core

28. 1 Which of the following mostly consists of liquid iron? Question A) Crust B) Mantle C) Outer core D) Inner core

29. Next > IV. Lithospheric Plates A. The plates of the outer layer of the Earth comprise the crust, and the solid part of the upper mantle. For this reason, they are often called lithospheric plates. B. The lithosphere floats on the semi-liquid asthenosphere. The asthenosphere allows the lithosphere to move, enabling the motion of the lithospheric plates. The map below shows all major plates and a number of minor plates. Eurasian plate Pacific plate Pacific plate Australian plate South American plate North American plate North American plate African plate Indian plate Nazca plate Arabian plate Caribbean plate Cocos plate Juan de Fuca plate Fillipino plate Antarctic plate

30. Next > V. What Causes Plate Motion? A. Imagine that you are cooking an egg in a saucepan full of water. As the water is heated and the temperature increases, the egg floating at the surface begins to move. C. In a similar way, convection currents within the Earth’s mantle cause the plates floating above to move. However, while convection in the saucepan takes a matter of seconds, convection within the mantle takes millions of years. B. This is because the hottest particles of water rise to the surface, where they cool and sink back down in a cycle called a convection current. The movement in the hot water causes the egg to move. Mantle Plates

31. 2 Where do the convection currents that cause plate motion originate? Question A) Crust B) Mantle C) Outer core D) Inner core

32. Next > VI. Plate Boundaries A. There are many convection currents within the mantle. The speed and direction of the currents vary. This means that plates are all moving with different speeds and directions. C. Although such events can occur in other parts of the Earth’s surface, the majority occur at plate boundaries. B. The plates collide or pull apart depending on their relative directions and speeds. The interactions of the plates at their boundaries cause geological events such as volcanic eruptions, earthquakes and the formation of mountains. Mantle Plates

33. Next > VII. Plate Boundaries A. There are three types of boundaries between plates: 1. Convergent – The boundary between two plates that are moving towards each other. 2. Divergent – The boundary between two plates that are pulling apart. 3. Sliding – The boundary between two plates that are sliding past each other horizontally. B. The interactions of plates at each type of boundary have different impacts on the Earth’s surface.

34. Next > VIII. Convergent Boundaries A. When two plates collide, one plate is forced below the other. C. Convergent boundaries also lead to the formation of volcanoes at the ocean floor. D. The edge of the lower plate is pushed into the mantle where it begins to melt and turn into magma. This extra magma within the Earth creates extra pressure, and the magma is forced out in a volcanic eruption. B. At convergent plate boundaries on the ocean floor, a trench is formed. Trenches are narrow, deep cuts in the ocean floor. Trench Plate begins to melt and turn into magma Extra magma forced out Volcano

35. Mountains Next > E. Volcanoes are also formed on land when both convergent plates are mainly made of continental crust rather than oceanic crust. F. The higher plate crumples at the boundary, forming mountains and volcanoes. The formation of mountains is very slow, occurring gradually as plates converge over millions of years. 1. For example, the Himalayas were formed when the Eurasian and Indian plates collided. This occurred about 50 million years ago, but the convergence continued for some time. Most of the mountains only reached their full heights during the last 10 million years.

36. Next > G. Earthquakes can occur at convergent boundaries as one plate grinds over the other, causing rock to deform and become brittle. H. Earthquakes occurring at convergent boundaries can be very large and devastating. I. Earthquakes at underwater convergent boundaries can create a tsunami – a potentially devastating wave that dumps an enormous mass of water onto coastal land when it breaks on a shore. Damage caused by a tsunami

37. 3 What is a convergent boundary? Question A) The boundary between two plates moving towards each other B) The boundary between two plates moving apart C) The boundary between two plates sliding past each other

38. Next > IX. Divergent Boundaries A. When a convergent boundary forces one plate to sink into the mantle, the edge melts and disappears. B. You might expect this to cause the Earth’s surface to shrink as some of the crust is lost. However, the Earth’s surface remains the same size. C. This is because, roughly the same amount of crust that is lost at a convergent boundary, is created when plates pull apart at a divergent boundary. New crust created Crust lost

39. Next > D. As plates pull apart, they cause cracks to appear in the surface. Eventually the cracks widen into a gap in the crust. Magma escapes through the cracks on to the surface from the mantle. The magma then hardens to form new crustal rock. E. “Volcanic activity” refers to magma escaping on to the surface. When the magma escapes quickly, mountains (including volcanoes) are formed. F. However, when the magma pushes on to the surface slowly, the new rock that is formed is relatively flat. Magma escapes Magma hardens to form rock

40. Next > G. Divergent boundaries that occur on the ocean floor can also lead to the formation of mountains and volcanoes. H. The Mid-Atlantic Ridge is a mostly underwater mountain range created by the divergent boundary between the North American and Eurasian plates. J. The North American and Eurasian plates are still spreading apart. The ocean floor grows at the Mid-Atlantic Ridge by about 2.5 cm a year. I. Some of the underwater mountains in the Ridge are taller than Mount Everest, the tallest mountain on land. The highest peaks extend above the surface of the ocean, forming islands. Mid-Atlantic Ridge

41. Next > X. Sliding Boundaries A. At sliding boundaries, also called transform boundaries, two plates slide past each other horizontally. B. When this happens, enormous stress is put on the rocks at the surface, causing them to deform. Eventually, the stress becomes so great that the rocks break apart, leaving a crack in the Earth’s surface. Such a crack is called a fault. C. When a fault appears, an enormous amount of energy is released in the form of an earthquake. San Andreas Fault, California

42. Next > XI. Sliding Boundaries A. Sliding boundaries do not destroy part of the crust, or create new crust. However, because sliding boundaries cause rock to deform, the edge of the plates may become jagged. B. Sliding boundaries and the resulting faults are more common at boundaries under the ocean than on land. Kunlun Fault, Tibet

43. 4 Which of the following boundaries does NOT result in the creation or destruction of crust? Question A) Convergent B) Divergent C) Sliding D) It is impossible to say

44. 5 "A fault can appear in the Earth's surface at a sliding boundary." Is this statement true or false? Answer True or False. Question

45. Summary After completing this presentation you should be able to: End > show knowledge and understanding of the composition of the Earth show knowledge and understanding of the effects of plate motion show knowledge and understanding of the movements of lithospheric plates

46. In this presentation you will: explore different landforms explore the constructive and destructive forces that shape the land ClassAct SRS enabled.

47. Many different landforms can be seen on the Earth today. These landforms have been shaped by different forces, such as earthquakes, volcanoes and erosion. Next > In this presentation, you will explore different landforms and the processes which create them. Some forces alter the land gradually over hundreds of years, while others change the landscape instantly. The same processes that shape the land today have occurred throughout the Earth’s history.

48. B. Plains along a coast are called coastal plains. They generally slope up from sea level to meet a higher landform. A. Plains are wide, level areas of land. They are usually lower than the other landforms around them. I. Landforms – Plains Next > C. Inland plains tend to be almost flat. D. Many populations have settled on plains because they have soil that is suited to farming and they are easy to build on because the land is flat. E. Plant life on plains tends to be forests in humid climates, and grass in dry climates. Major plains of the world

49. Next > II. Landforms – Deserts A. A desert is an area of land that is very dry. Hardly any rain falls on deserts and they are too dry to support much plant life. C. Deserts do not necessarily have sand. Desert terrain varies greatly. They can be mountainous or very flat. Major deserts of the world B. Deserts are usually located downwind of mountain ranges. Air loses moisture as it rises to pass over the mountains, reducing rainfall in the areas the air travels to. When rainfall is dramatically reduced, a desert may be created.

50. Tibetan Plateau Next > III. Landforms – Plateaus A. A plateau is a broad, relatively flat area that is at a higher elevation than the land around it. Plateaus can be described as elevated plains. C. A small plateau that has steep slopes on all sides is often referred to as a table or a mesa. B. Usually, a plateau is separated from lower surrounding land by at least one steep slope. D. The Tibetan Plateau is the highest region in the world.

51. Next > IV. Landforms – Continental Divides A. A watershed is an area of land that slopes down to a body of water, such as a river, a lake, or an ocean. Rain or melted snow in the watershed drains into the body of water. B. A continental divide is a border between two watersheds. The land in a continental divide is elevated, so that water drains down from the divide into bodies of water on either side. C. Continental divides are not always easy to identify. For example, North America has four distinct continental divides, but the continental divides of Europe and Asia are much harder to distinguish. Continental divides of North America

52. Next > C. Mountains are the source of all of the major rivers in the world. A. A mountain is an area of land that reaches a greater height than the surrounding land. Unlike a plateau, which can be very broad, a mountain has a limited area. V. Landforms – Mountains B. Mountains are generally bigger than hills – they are steeper and higher. However, the point at which a landform is referred to as a mountain rather than a hill varies from place to place. Major mountain ranges

53. 1 What is a plain? Question A) A mountainous area of land that is very dry B) A wide, level area of land that is lower than surrounding landforms C) A border between two watersheds D) A broad, flat area that is higher than surrounding landforms

54. 2 What name is given to elevated land that is a border between two watersheds? Question A) Desert B) Mountain range C) Plateau D) Continental divide

55. Next > VI. Constructive and Destructive Forces A. The landforms that we see today have been created and shaped over time by a combination of different factors. B. Constructive forces build up or construct landforms. The following are examples of constructive forces: 1.Crustal deformation 2.Volcanic eruption 3.Earthquakes 4.Deposition of sediment C. Destructive forces break down existing landforms. The following are examples of destructive forces: 1.Weathering 2.Erosion 3.Glaciers

56. 3 Which of the following is a destructive force? Question A) Earthquake B) Crustal deformation C) Glacial action D) Deposition

57. Plate boundaries – each color represents a different plate Next > VII. Constructive Forces – Crustal Deformation B. The ways in which the plates move in relation to each other can dramatically change the shape of the Earth’s surface. This is known as crustal deformation. It occurs at the boundary between two plates. A. The Earth’s crust is broken up into a number of different plates. These plates move very slowly. We cannot feel the movement of the plates because they generally only move a few centimeters each year. C. The different ways in which plates interact cause different types of crustal deformation. Volcanoes and mountains are examples of crustal deformation. Crustal deformation in Iceland

58. VIII. Constructive Forces – Volcanoes Next > Semeru Mauna Loa A. When a volcano erupts, magma (molten rock) from inside the Earth escapes onto the surface where it cools and hardens into rock. This rock becomes a new landform. Mountains are often formed in this way. C. Volcanoes are generally thought of as being cone shaped, like Semeru in Indonesia. However, volcanoes can also be relatively flat, like Mauna Loa in Hawaii. This is the case when magma escapes onto the surface very slowly. B. Volcanic eruptions can be very fast and violent, or slow and gradual.

59. E. When plates pull apart, they leave an opening in the Earth’s crust which allows the magma to escape. Next > F. When plates collide, one plate may rise above the other, forcing it down below the surface. The temperatures inside the Earth are very high, causing the submerged part of the plate to melt and turn into magma. This magma is then forced out on to the Earth’s surface by a volcanic eruption. D. Volcanoes usually occur when two or three plates move towards each other or away from each other.

60. IX. Constructive Forces – Earthquakes C. When the rock breaks, energy is released and the rock moves, causing an earthquake. The size of the earthquake is usually connected to the size of the fault. A. Earthquakes occur when plates slide past each other in opposite directions. The movement that results in an earthquake could take up to hundreds of thousands of years. B. When plates try to move in opposite directions at boundaries, rock at the surface begins to stretch. Eventually, the stress on the rock is so great that it breaks apart. The break, known as a fault, rapidly moves along the boundary between the plates. Next > The San Andreas Fault in California

61. Next > X. Constructive Forces – Deposition A. As wind, water and ice move, they carry materials with them. The materials may be soil, or broken down rock. B. When the forces causing the material to move can no longer overcome the resistance of friction (a force that resists motion) or the weight of the material, the material is left behind. This process is known as deposition. C. The deposited material gathers in layers which gradually build up over time. This process creates new landforms very slowly over many years. D. The process of deposition can also be very rapid, the deposition of material from a landslide, for example.

62. 4 "Although volcanoes are generally thought of as being cone-shaped, they can also be relatively flat." Is this statement true or false? Answer True or False. Question

63. Next > XI. Destructive Forces – Weathering A. Weathering is the process by which landforms are broken down by water, wind, ice, pressure or heat. B. The effects of weathering on landforms can be very small and slow, only noticeable after many years. C. Some effects of weathering can be much more dramatic. For example, when water gets into cracks or holes in rocks and freezes, it expands. The pressure that results from this can cause rocks to crack and shatter.

64. Next > XII. Destructive Forces – Erosion A. Erosion is related to weathering. It is caused by factors such as wind, water, ice and gravity acting on materials such as soil or rock. D. For example, a river will erode a sandy bank much more quickly than a bank made of solid rock. B. However, erosion causes solid materials to move, while weathering causes the materials to break down without movement. C. Erosion can occur over thousands of years, or in a relatively short space of time. The speed at which a material is eroded depends on the nature of the material, and the force acting on it.

65. Next > XII. Destructive Forces – Glacial Action A. A glacier is a large river of ice. Glaciers remain permanently frozen, therefore they only exist in cold climates. B. Gravity causes glaciers to move. However, because glaciers contain a huge amount of ice, they are very heavy. There is also a lot of friction between the bottom of the glacier and the ground. These factors mean that glaciers move very slowly, although their speeds vary. C. Some glaciers may only move a few centimeters a year, while others move a number of meters in a year.

66. Next > D. Glaciers erode the land underneath as they move. E. Fragments of rock may be softened or loosened and carried by the glacier. As these rocks are dragged along, the bottom of the glacier becomes like sandpaper, smoothing the rock which it passes over. F. Glacial erosion creates rounded “U”-shaped valleys which are flat and smooth at the bottom. Valleys created by glaciers that existed thousands of years ago can be seen all over the world.

67. 5 Which of the following causes landforms to break down in their place, without moving the material? Question A) Weathering B) Erosion C) Glacial action

68. Next > XIII. Occasional Events A. A combination of constructive and destructive processes continually shape the surface of the Earth. 1. For example, when a meteor collides with the Earth, the site of impact is often marked by a crater. B. However, occasional events, such as a meteor striking the Earth, can also affect the landscape. C. The size of the crater depends on the size of the object that hit the Earth. A large impact can be very destructive, destroying life and landforms across a wide area. Impact crater

69. Summary After completing this presentation you should be able to: End > show knowledge and understanding of different landforms show knowledge and understanding of the processes that shape the land