Unit Study Guide: Earth s Changing Surface

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1 Name Date Per Unit Study Guide: Earth s Changing Surface I Can Statements I Can Statements are the learning targets for each unit. By the time you take the test for this unit, you should be able to confidently say: I can identify processes that change the Earth's surface rapidly. I can identify processes that change the Earth's surface slowly over time. I can explain how different types of erosion move sediment. I can explain how different types of weathering break down rocks. I can explain the difference between weathering and erosion. I can trace the energy flow from inside the Earth to the surface (through earthquakes and volcanoes). I can explain how earthquakes occur. Teach the Concepts One great way to study is to explain concepts to others. Teach the following concepts to a parent, grandparent, aunt, uncle, or even an older sibling. ü Explain the energy transfers that take place to go from thermal energy in Earth s core to an earthquake. ü Explain the energy transfers that take place to go from thermal energy in Earth s core to a volcano. ü Describe the agents of erosion give examples of each. ü Explain the difference between weathering, erosion and deposition. ü Explain seismic waves (what they are, the different types, etc.) ü List the things that change Earth s surface quickly, and the things that change Earth s surface very slowly. ü Describe 3 types of volcano including eruption and energy type. ü Explain how volcanoes and earthquakes change the surface of the earth. Read/Summarize Signature Weathering, Erosion and Deposition: Rock fragments, minerals, and organic matter make up soil, but how do big rocks get so small? It happens through a process called weathering. The weathering process is much like the digestion process. Rocks are "chewed up by the wind, rain, and acids into smaller and smaller pieces called sediment. There are several types of weathering including both mechanical and chemical processes such as freeze/thaw, abrasion, running water and glacier movement.

2 Erosion is the movement of sediments from one place to another. There are several agents of erosion including water, wind, ice and gravity, each moving sediment through mechanical means. For example, gravity is an agent of erosion because it pulls sediment downhill. The force of gravity also pulls water down all the mountains and valleys, and that running water carries sediment with it. Atmospheric processes of water, wind, and ice working under the influence of gravity are the greatest sources of erosion on the surface of Earth. Volcanoes are mountains that are built by the accumulation of their own eruptive products -- lava, ash flows, and airborne ash and dust. A volcano is most commonly a cone-shaped hill or mountain built around a vent that connects with reservoirs of molten rock below the surface of the Earth. The term volcano also refers to the opening or vent through which the molten rock and associated gases are expelled. Thermal energy from the earth s core transfers thermal energy to the mantle, and that mantle transfers thermal energy to rock deep in the crust, which causes the rock to melt and become magma. Driven by buoyancy and gas pressure, the molten rock, which is less dense than the surrounding solid rock, forces its way upward and may ultimately break though the Earth's crust. If so, an eruption begins, and the molten rock may pour from the vent as non-explosive lava flows, or if may shoot violently into the air as dense clouds of lava fragments. Some of the finer ejected materials may be carried by the wind only to fall to the ground many miles away. Volcanoes can be very dangerous and can do a lot of damage. Volcanic eruptions have caused mudslides, avalanches, and floods. They can also trigger other things, like tsunamis, earthquakes, and rock falls. In the United States, the most active volcanoes are in Alaska, Washington, Oregon, California, and Hawaii. In fact, the Hawaiian Islands were actually created by volcanoes under the ocean. Cinder cone volcanoes have steep sides but aren t very tall. When they erupt, small solid fragments of rock and ash come out of the volcano. Shield volcanoes are also made of hardened lava. When they erupt, their lava flows are very thin and runny. The lava spreads out and becomes new soil, making these volcanoes very large with gentle sloping sides. Composite (strato) cone volcanoes are the most common. They are very tall, and they erupt with runny lava followed by explosive thick lava. They also have a lot of ash. These volcanoes have very steep sides because the ash and thick lava cools and becomes part of the surface. An earthquake is the vibration, sometimes violent, of the Earth's surface that follows a release of energy in the Earth's crust. This energy can be generated by a sudden break of rock of the crust, by a volcanic eruption, or even by manmade explosions. Most destructive quakes, however, are caused by breaks of the crust. The crust may first bend and then, when the stress

3 exceeds the strength of the rocks, break and "snap" to a new position. In the process of breaking, vibrations called "seismic waves" are generated. These waves travel outward from the source of the earthquake along the surface and through the Earth at varying speeds depending on the type of wave and material through which they move. Some of the vibrations are of high enough frequency to be audible, while others are of very low frequency. These vibrations cause the entire planet to vibrate or ring like a bell or tuning fork. A fault is a fracture in the Earth's crust along which two blocks of the crust have moved in relation to each other. Faults are divided into three main groups, depending on how they move. Normal faults occur in response to pulling or tension; the overlying block moves down fault plane. Thrust (reverse) faults occur in response to squeezing or compression; the overlying block moves up the fault plane. Strike-slip (lateral) faults occur in response to either type of stress; the blocks move horizontally past one another. Geologists have found that earthquakes tend to reoccur along faults, which reflect zones of weakness in the Earth's crust. Even if a fault zone has recently experienced an earthquake, however, there is no guarantee that all the stress has been relieved. Another earthquake could still occur. The focus (hypocenter) of an earthquake is where an earthquake's energy originates. The epicenter of an earthquake is the point on the Earth's surface directly above the focus. When an earthquake occurs, the energy is released as seismic waves. Seismic waves are waves of energy that travel in all directions from the breaking point of the earthquake. The three general types of produced by earthquakes are compression waves, shear waves, and surface waves. Surface waves travel along the earth s surface, and P-waves and S-waves travel through the earth. Surface waves usually have the strongest vibrations and cause most of the damage done by earthquakes. Because compressional waves travel at great speeds and ordinarily reach the surface first, they are often called "primary waves" or simply "P" waves. Shear waves do not travel as rapidly through the Earth's crust and mantle; they are called "secondary" or "S" waves. Check Yourself! 1. What is the original source of energy that causes earthquakes? 2. What is the original source of energy that causes volcanoes? 3. Draw an energy chain showing the transfer of energy that causes an earthquake. 4. Draw an energy chain showing the transfer of energy that causes a volcano.

4 5. Give three specific examples of weathering: 6. Give three specific examples of erosion: 7. How are weathering and erosion different? 8. Define mechanical energy. What is another name for mechanical energy? 9. Define heat energy. What is another name for heat energy? 10. What causes volcanoes? What type of energy does a volcano transfer? 11. What determines if a volcano will be explosive or non-explosive? 12. What is the difference between weathering and erosion? 13. What is the difference between chemical and mechanical weathering? 14. Describe how plants can break down rock. 15. List five (5) of the causes of weathering. 16. List the forces (agents) that cause erosion. 17. Describe how WIND moves different sizes of sediment. 18. Describe how WATER moves different sizes of sediment. 19. Define abrasion. 20. What are some environments where abrasion can occur? List at least three. 21. What causes earthquakes?

5 22. What type of energy does an earthquake transfer? 23. Does the surface of the earth change quickly or slowly? Both? Explain. 24. Describe the 3 types of seismic waves: How do they move? What materials can they pass through? How fast do they move? 25. Fill in the table below: Processes/events that change earth's surface quickly: Processes/events that change earth's surface slowly: 26. Write the correct volcano type(s) next to each characteristic. has steep slopes has gradual, rounded slopes relatively small has thick, sticky lava (high viscosity) has thin, runny lava (low viscosity) has non-explosive eruptions has explosive eruptions sides are made of loose pieces of pyroclastic material 27. Draw a diagram of each volcano type. Volcano type: Volcano type: Volcano type: Drawing: Drawing: Drawing: 28. Write the correct name for each fault (strike-slip, normal, or reverse).

6 29. Match each description and picture with the correct wave type. a. S-waves b. P-waves c. Surface Waves The first wave type to reach the surface. The fastest of the seismic waves. Cannot travel through liquids or gases. Also known as secondary waves. Also known as primary waves. The last waves to reach the surface. The waves that cause the most damage. 30. Describe how each agent of erosion moves sediment. Then give one specific example. Agent How does it move sediment? Example: Gravity Wind Running Water Glacier Other: 31. Match the process with its description. Process weathering erosion deposition Description a. movement of rock particles by wind, water, ice, or gravity b. breaking down of rock on Earth's surface c. collecting sediment into a new place 32. For each example below, write the type(s) of weathering. Rocks get polished on the floor of a river (riverbed). Rock formations in the desert are carved into interesting shapes. The rock underneath a glacier (bedrock) gets long, deep scratches in it. Slightly acidic rain dissolves limestone. A seed gets planted in a crack in a rock and grows larger and larger. Flash floods carry sediment down a slot canyon, carving the canyon. Lichen grows on a rock and slowly breaks it down over time. Water seeps into a crack in a rock and freezes. 33. For each example below, write the agent(s) of erosion that cause it. Rock at the top of a cliff suddenly falls. Sand is carried in water as it rushes down a slot canyon after a flash flood. As you step on the mountain path, bits of rock and soil fall downhill. A slow, muddy river carries silt and mud particles downstream. Wind rolls large sand grains along the desert floor. A human gets mud on her feet during a camping trip, gets home and wipes the mud on her doormat. Boulders, pebbles, and mud are dragged along underneath the weight of a glacier. After a heavy rainfall, soil on a desert hill slides to the bottom. Dust flies through the air.