CHAPTER 12 SECTION 2 Wind Erosion And Deposition

NameCHAPTER 12ClassDateAgents of Erosion and DepositionSECTION2 Wind Erosion and DepositionNational ScienceEducation StandardsBEFORE YOU READAfter you read this section, you should be able to answerthese questions:ES 1c, 2a How can wind erosion shape the landscape? How can wind deposition shape the landscape?How Can Wind Erosion Affect Rocks?Wind can move soil, sand, and small pieces of rock.Therefore, wind can cause erosion. However, some areasare more likely to have wind erosion than other areas.For example, plant roots help to hold soil and rock inplace. Therefore, areas with few plants, such as desertsand coastlines, are more likely to be eroded by wind.These areas also may be made of small, loose rock particles. Wind can move these particles easily.Wind can shape rock pieces in three ways: saltation,deflation, and abrasion.SALTATIONSTUDY TIPLearn New Words As youread this section, underlinewords you don’t understand.When you figure out whatthey mean, write the wordsand their definitions in yournotebook.READING CHECK1. Explain How do plantroots help to prevent winderosion?Wind moves large grains of soil, sand, and rock by saltation. Saltation happens when sand-sized particles skipand bounce along in the direction that the wind is moving. When moving sand grains hit one another, some ofthe grains bounce up into the air. These grains fall backto the ground and bump other grains. These other grainscan then move forward.7IND DIRECTION3MALLER PARTICLES ARE LIFTEDAND CARRIED BY THE WIND TAKE A LOOK2. Apply Concepts Whycan’t the wind lift and carrylarge particles?,ARGER PARTICLES BOUNCE ANDSKIP ALONG THE GROUND Copyright by Holt, Rinehart and Winston. All rights reserved.Interactive Textbook217Agents of Erosion and Deposition

NameSECTION 2ClassDateWind Erosion and Deposition continuedDEFLATIONREADING CHECK3. Define What is deflation?Wind can blow tiny particles away from larger rockpieces during deflation. Deflation happens when windremoves the top layers of fine sediment or soil and leavesbehind larger rock pieces.Deflation can form certain land features. It can produce desert pavement, which is a surface made of pebbles and small, broken rocks. In some places, the windcan scoop out small, bowl-shaped areas in sediment onthe ground. These areas are called deflation hollows.ABRASIONWind can grind and wear down rocks by abrasion.Abrasion happens when rock or sand wears down largerpieces of rock. Abrasion happens in areas where thereare strong winds, loose sand, and soft rocks. The windblows the loose sand against the rocks. The sand acts likesandpaper to erode, smooth, and polish the rocks.ProcessDescriptionLarge particles bounce and skip along the ground.TAKE A LOOK4. Complete Fill in the blankspaces in the table.DeflationAbrasionWhat Landforms Are Produced by WindDeposition?Critical Thinking5. Infer What do you thinkis the reason that fast windscan carry larger particles thanslower winds?Wind can carry material over long distances. The windcan carry different amounts and sizes of particles depending on its speed. Fast winds can carry large particles andmay move a lot of material. However, all winds eventuallyslow down and drop their material. The heaviest particlesfall first, while light material travels the farthest.LOESSWind can deposit extremely fine material. Thick deposits of this windblown, fine-grained sediment are known asloess. Loess feels like talcum powder. Because the windcan carry light-weight material so easily, a loess depositcan be found far away from its source. In the UnitedStates, loess deposits are found in the Midwest, theMississippi Valley, and in Oregon and Washington states.Copyright by Holt, Rinehart and Winston. All rights reserved.Interactive Textbook218Agents of Erosion and Deposition

NameSECTION 2ClassDateWind Erosion and Deposition continuedDUNESBarriers, such as plants and rocks, can cause wind toslow down. As it slows, the wind deposits particles ontop of the barrier. As the dropped material builds up, thebarrier gets larger. The barrier causes the wind to slowdown even more. More and more material builds up onthe barrier until a mound forms.A mound of wind-deposited sand is called a dune.Dunes are common in sandy deserts and along sandyshores of lakes and oceans.STANDARDS CHECKES 1c Land forms are the resultof a combination of constructiveand destructive forces. Constructive forces include crustaldeformation, volcanic eruption,and deposition of sediment,while destructive forces includeweathering and erosion.6. Define What is a dune?THE MOVEMENT OF DUNESWind conditions affect a dune’s shape and size. As thewind blows sand through a desert, it is removed fromsome places and deposited in others. This can causedunes to seem to move across the desert.In general, dunes move in the same direction the windis blowing. A dune has one gently sloped side and onesteep side. The gently sloped side faces the wind. It iscalled the windward slope. The wind constantly movessand up this side. As sand moves over the top of thedune, the sand slides down the steep side. The steep sideis called the slip face.Wind directionWindwardslopeSlip faceREADING CHECK7. Identify In what directiondo dunes generally move?TAKE A LOOK8. Compare How is thewindward slope of a dunedifferent from the slip face?Direction ofdune movementThe wind blows sand up the windward slope of the dune. The sand moves over thetop of the dune and falls down the steep slip face. In this way, dunes move acrossthe land in the direction that the wind blows.Copyright by Holt, Rinehart and Winston. All rights reserved.Interactive Textbook219Agents of Erosion and Deposition

NameClassDateSection 2 ReviewNSESES 1c, 2aSECTION VOCABULARYabrasion the grinding and wearing away of rocksurfaces through the mechanical action ofother rock or sand particlesdeflation a form of wind erosion in which fine,dry soil particles are blown awaydune a mound of wind-deposited sand thatmoves as a result of the action of windloess fine-grained sediments of quartz, feldspar,hornblende, mica, and clay deposited by the windsaltation the movement of sand or othersediments by short jumps and bounces thatis caused by wind or water1. Identify Give two land features that can form because of deflation.2. Describe What areas are most likely to be affected by wind erosion? Give twoexamples.3. Identify The figure shows a drawing of a sand dune. Label the windward slopeand the slip face. Draw an arrow to show the direction of the wind.4. Explain How do dunes form?5. Apply Concepts Wind can transport particles of many different sizes. What sizedparticles are probably carried the farthest by the wind? Explain your answer.Copyright by Holt, Rinehart and Winston. All rights reserved.Interactive Textbook220Agents of Erosion and Deposition

Earth Science Answer Key continued7. A beach is an area along a shoreline that is8.9.10.11.12.13.7. the same direction the wind is blowing8. The windward slope has a gentler angle thancovered by materials that were carried there bywaves.quartzSand particles are washed away during storms.Waves wash onto the beach in the samedirection that they wash off the beach, sothere is no sideways movement of water.a ridge of deposited material in open watera sandbar that is connected to the shorelineBarrier spits are connected to the shore, butbarrier islands are not.the slip face.Review1. desert pavement, deflation hollows2. areas with little plant cover and/or with fine,loose soil or sand, such as coastlines anddeserts3. Student should label the gently sloping side“windward slope” and the steeply dipping side“slip face”; the arrow should point to the right.4. When wind hits a barrier, such as a plant, arock, or a building, it slows down. The sediment that it has been carrying is depositedonto the barrier, making the barrier larger.Eventually, the barrier is completely coveredby sediment, forming a dune.5. The wind can carry small particles thefarthest because they weigh the least.Review1. A shoreline is the boundary between land2.3.4.5.and water. A beach is part of a shoreline thatis made of deposited sediment.Answers include: wind (produces waves,which erode and add to the shore), wavesThe sand can have different colors, whichcome from the kind of rock it is made from.Black sand can form from the weathering ofdark-colored lava. Light-colored sand may bemade of light-colored minerals, such as quartz.Waves carry sand up the shore parallel totheir direction of travel. The waves washback into the ocean perpendicular to theshoreline. This causes sand to move in azig-zag pattern parallel to the shoreline.sea arches, sea stacks, headlands, wave-cutterraces, sea cavesSECTION 3 EROSION AND DEPOSITIONBY ICE1.2.3.4.continental and alpinea huge, moving sheet of iceGlaciers are made of frozen water.Horns and arêtes form when two or morecirques affect the same part of a mountain.5. It contains particles of many different sizes.6. Stratified drift is material that is depositedby water that comes from melting glaciers.SECTION 2 WIND EROSION ANDDEPOSITIONReview1. till, stratified drift2. lateral, medial, terminal, ground3. Continental glaciers form on large areas of1. They hold the soil and rock in place.2. Large particles are too heavy, and the winddoesn’t have enough energy to carry them.3. the process in which small sediment particles are removed by the wind, leavingbehind larger particles4. ProcessDescriptionSaltationLarge particles bounce andskip along the ground.DeflationSmall particles are removedby wind.AbrasionRock pieces are worn away bywind-carried sand.relatively flat land. Alpine glaciers form ontop of high mountains.4. Snow falls on an area but does not meltover the course of the year. Over time, moresnow builds up in the area. The weight ofthe snow above pushes down on the snowbelow, causing the snow at the bottom toturn into ice. This ice is a glacier.5. A block of ice is left behind as a glacierretreats. When the ice melts, the material init gets deposited around the outside of theblock. This makes a depression, called akettle, in the center.5. Fast winds have more energy, so they canlift larger particles.6. a mound of wind-deposited sandCopyright by Holt, Rinehart and Winston. All rights reserved.Interactive Textbook Answer Key49Earth Science

12. a sandbar that is connected to the shoreline 13. Barrier spits are connected to the shore, but barrier islands are not. Review 1. A shoreline is the boundary between land and water. A beach is part of a shoreline that is made of deposited sediment. 2. Answers include: wind (produces waves, which erode and add to the shore), waves 3.