chapter 12: water erosion and deposition - wikispaces · characteristics of surface water,...

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Nature’s SculptorBryce Canyon National Park in Utah ishome to the Hoodoos—tall, column-likeformations. They were made by one of themost powerful forces on Earth—movingwater. In this chapter you will learn howmoving water shapes Earth’s surface.

What might have formed thenarrowing of each Hoodoo? What will happen if this narrowingcontinues?

Science Journal

sections

1 Surface Water

2 Groundwater

3 Ocean ShorelineLab Classifying Types of SandLab Water Speed and Erosion

Virtual Lab How do certainfactors affect the erosion ofsoil by water?

Water Erosion and Deposition

Sunshine State Standards—SC.D.1: The student recognizes that processes in the lithosphere,atmosphere, hydrosphere, and biosphere interact to shape the Earth.

(bkgd.)William Manning/The Stock Market/CORBIS

Characteristics of SurfaceWater, Groundwater, andShoreline Water Make the

following Foldable to help you identify the mainconcepts relating to surface water, groundwater,and shoreline water.

Fold the top of a vertical piece ofpaper down and the bottom up todivide the paper into thirds.

Turn the paper horizontally;unfold and label the three columnsas shown.

Read for Main Ideas As you read the chapter,list the concepts relating to surface water,groundwater, and shoreline water.

STEP 2

STEP 1

Start-Up Activities

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Ground- water

ShorelineWater

SurfaceWater

2. Place an alumi-num pie pan onyour desktop.

3. Put a pile of drysoil about 7 cmhigh into the pan.

4. Slowly drip water from a dropper onto thepile and observe what happens next.

5. Drip the water faster and continue toobserve what happens.

6. Repeat steps 1 through 4, but this timechange the slope of the hill by increasingthe central pile. Start again with dry soil.

7. Think Critically In your Science Journal,write about the effect the water had onthe different slopes.

Preview this chapter’s contentand activities at fl6.msscience.com

SC.D.1.3.1SC.H.1.3.5

Model How Erosion WorksMoving water has great energy. Sometimesrainwater falls softly and soaks slowly intosoil. Other times it rushes down a slope withtremendous force and carries away valuabletopsoil. What determines whether rain soaksinto the ground or runs off and wears awaythe surface?

1. Complete a safety worksheet.

LA.A.1.3.4

(bkgd.)William Manning/The Stock Market/CORBIS, (inset)Aaron Haupt

http://fl6.msscience.com

352 CHAPTER 12 Water Erosion and Deposition

RunoffPicture this. You pour a glass of milk and it overflows, spilling

onto the table. You grab a towel to clean up the mess, but the milkis already running through a crack in the table, over the edge, andonto the floor. This is similar to what happens to rainwater whenit falls to Earth. Some rainwater soaks into the ground and someevaporates, turning into a gas. The rainwater that doesn’t soakinto the ground or evaporate runs over the ground. Eventually, itenters streams, lakes, or the ocean. Water that doesn’t soak intothe ground or evaporate but instead flows across Earth’s surface iscalled runoff. If you’ve ever spilled milk while pouring it, you’veexperienced something similar to runoff.

Factors Affecting Runoff What determines whether rainsoaks into the ground or runs off? The amount of rain and thelength of time it falls are two factors that affect runoff. Light rainfalling over several hours probably will have time to soak intothe ground. Heavy rain falling in less than an hour or so will runoff because it cannot soak in fast enough, or it can’t soak inbecause the ground cannot hold any more water.

■ Identify the causes of runoff.■ Compare rill, gully, sheet, and

stream erosion.■ Identify three different stages of

stream development.■ Explain how alluvial fans and

deltas form.

Runoff and streams shape Earth’ssurface.

Surface Water

Figure 1 In areas with gentle slopes and vegetation, little runoff and ero-sion take place. Lack of vegetation has led to severe soil erosion in some areas.

Benchmarks—SC.D.1.3.1 (pp. 352–362): The student knows that mechanical and chemical activitiesshape and reshape the Earth’s land surface by eroding rock and soil in some areas and depositing themin other areas, sometimes in seasonal layers; SC.D.1.3.5 (pp. 352–362): The student understands con-cepts of time and size relating to the interaction of Earth’s processes ….

Also covers: SC.D.1.3.3 (pp. 352–362), SC.D.1.3.4 Annually Assessed (p. 353), SC.H.1.3.5 AnnuallyAssessed (p. 361), SC.H.1.3.6 (p. 353), SC.H.2.3.1 (pp. 352–362)

Review Vocabularyerosion: transport of surface

materials by agents such as grav-ity, wind, water, or glaciers

New Vocabulary

• runoff • drainage basinerosion • meander

• channel deposition

FCAT Vocabulary

(l)Michael Busselle/Stone/Getty Images, (r)David Woodfall/DRK Photo

Other Factors Another factor that affects the amount ofrunoff is the steepness, or slope, of the land. Gravity causeswater to move down slopes. Water moves rapidly down steepslopes so it has little chance to soak into the ground. Watermoves more slowly down gentle slopes and across flat areas.Slower movement allows water more time to soak into theground.

Vegetation, such as grass and trees, also affects the amount ofrunoff. Just like milk running off the table, water will run offsmooth surfaces that have little or no vegetation. Imagine atablecloth on the table. What would happen to the milk then?Runoff slows down when it flows around plants. Slower-movingwater has a greater chance to sink into the ground. By slowingdown runoff, plants and their roots help prevent soil from beingcarried away. Large amounts of soil may be carried away in areasthat lack vegetation, as shown in Figure 1.

Effects of Gravity When you lie on theground and feel as if you are being held in

place, you are experiencing the effects of gravity. Gravity isan attracting force that all objects have for one another. Thegreater the mass of an object is, the greater its force of gravityis. Because Earth has a much greater mass than any of theobjects on it, Earth’s gravitational force pulls objects towardits center. Water runs downhill because of Earth’s gravita-tional pull. When water begins to run down a slope, it picksup speed. As its speed increases, so does its energy. Fast-moving water, shown in Figure 2, carries more soil than slow-moving water does.

Figure 2 During floods, thehigh volume of fast-moving watererodes large amounts of soil.

SECTION 1 Surface Water 353

Conservation Farmerssometimes have to farm onsome kind of slope. Thesteeper the slope, the moreerosion will occur. Notonly is slope an importantfactor, but other factorshave to be considered aswell. The Natural ResourcesConservation Service, agovernment agency, studiesthese factors to determinesoil loss from a given area.Find out what other factorsthis agency uses to deter-mine soil loss.

Tim

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Water ErosionSuppose you and several friends walk the same way to school

each day through a field or an empty lot. You always walk in thesame footsteps as you did the day before. After a few weeks,you’ve worn a path through the field. When water travels downthe same slope time after time, it also wears a path. Erosion is acombination of natural processes that wears away surface mate-rials and moves them from one place to another.

Rill and Gully Erosion You may have noticed a groove orsmall ditch on the side of a slope that was left behind by runningwater. This is evidence of rill erosion. Rill erosion begins when asmall stream forms during a heavy rain. As this stream flowsalong, it has enough energy to erode and carry away soil. Watermoving down the same path creates a groove, called a channel,on the slope where the water eroded the soil. If water frequentlyflows in the same channel, rill erosion may change over timeinto another type of erosion called gully erosion.

During gully erosion, a rill channel becomes broader anddeeper. Figure 3 shows gullies that were formed when water car-ried away large amounts of soil.

Sheet Erosion Water often erodes without being in a chan-nel. Rainwater that begins to run off during a rainstorm oftenflows as thin, broad sheets before forming rills and streams. Forexample, when it rains over an area, the rainwater accumulatesuntil it eventually begins moving down a slope as a sheet, likethe water flowing off the hood of the car in Figure 4. Water alsocan flow as sheets if it breaks out of its channel.

Figure 3 Heavy rains canremove large amounts of sedi-ment, forming deep gullies inthe side of a slope.

Figure 4 When water accumu-lates, it can flow in sheets like thewater seen flowing over the hoodof this car.

354 CHAPTER 12(t)Grant Heilman Photography, (b)KS Studios

Floodwaters spilling out of a river can flow as sheets over thesurrounding flatlands. Streams flowing out of mountains fanout and may flow as sheets away from the foot of the mountain.Sheet erosion occurs when water that is flowing as sheets picksup and carries away sediments.

Stream Erosion Sometimes water continues to flow along alow place it has formed. As the water in a stream moves along, itpicks up sediments from the bottom and sides of its channel. Bythis process, a stream channel becomes deeper and wider.

The sediment that a stream carries is called its load. Waterpicks up and carries some of the lightweight sediments, calledthe suspended load. Larger, heavy particles called the bed loadjust roll along the bottom of the stream channel, as shown inFigure 5. Over time, water can even dissolve some rocks andcarry them away in solution. The different-sized sedimentsscrape against the bottom and sides of the channel like a pieceof sandpaper. Gradually, these sediments can wear away the rockby a process called abrasion.

Figure 5 This cross section of astream channel shows the locationof the suspended load and the bedload.Describe how the stream carriesdissolved material.


An animated version of this diagram is available atfl6.msscience.com

Bed load

Suspended load



River System DevelopmentHave you spent time near a river or stream in your commu-

nity? Each day, millions of liters of water probably flow throughthat stream. Where does all the water come from? Where is itflowing to?

River Systems Streams are parts of river systems. The watercomes from rills, gullies, and smaller streams located upstream.Just as the tree in Figure 6 is a system containing twigs,branches, and a trunk, a river system also has many parts.Runoff enters small streams, which join together to form largerstreams. Larger streams come together to form rivers. Riversgrow and carry more water as more streams join.

Drainage Basins A drainage basin is the area of land fromwhich a stream or river collects runoff. Compare a drainagebasin to a bathtub. Water that collects in a bathtub flows towardone location—the drain. Likewise, all of the water in a river sys-tem eventually flows to one location—the main river, or trunk.The largest drainage basin in the United States is the MississippiRiver drainage basin, shown in Figure 6.

What is a drainage basin?

Columbia RiverDrainage Basin

Mississippi RiverDrainage Basin

Colorado RiverDrainage Basin

MEXICO

CANADAFigure 6 River systems can becompared with the structure of atree.

The system of twigs, branches,and trunk that make up a tree issimilar to the system of streamsand rivers that make up a riversystem.

A large number of the streams andrivers in the United States are part ofthe Mississippi River drainage basin,or watershed.Identify What river represents the trunkof this system?

Topic: Drainage BasinsVisit fl6.msscience.com for Weblinks to information aboutdrainage basins in your region.

Activity Locate the drainagebasin in which you live. Make aposter showing the shape, orboundary, of the drainage basin.Also include the main river, ortrunk, and the major tributaries,or branches.

LA.B.2.3.4

Mel Allen/ICL/Panoramic Images


Stages of StreamDevelopment

Streams come in a variety of forms.Some are narrow and swift-moving, andothers are wide and slow-moving.Streams differ because they are in differ-ent stages of development. These stagesdepend on the slope of the ground overwhich the stream flows. Streams are clas-sified as young, mature, or old. Figure 8shows how the stages come together toform a river system.

The names of the stages of develop-ment aren’t always related to the actualage of a river. The New River in WestVirginia is one of the oldest rivers inNorth America. However, it has a steepvalley and flows swiftly. As a result, it isclassified as a young stream.

Young Streams A stream that flowsswiftly through a steep valley is a youngstream. A young stream may have white-water rapids and waterfalls. Water flowingthrough a steep channel with a rough bottom has a high levelof energy and erodes the stream bottom faster than its sides.

Mature Streams The next stage in the development of astream is the mature stage. A mature stream flows moresmoothly through its valley. Over time, most of the rocks in thestreambed that cause waterfalls and rapids are eroded by run-ning water and the sediments it carries.

Erosion is no longer concentrated on the bottom in a maturestream. A mature stream starts to erode more along its sides, andcurves develop. These curves form because the speed of thewater changes throughout the width of the channel.

Water in a shallow area of a stream moves slower because itdrags along the bottom. In the deeper part of the channel, thewater flows faster. If the deep part of the channel is next to oneside of the river, water will erode that side and form a slightcurve. Over time, the curve grows to become a broad arc called ameander (mee AN dur), as shown in Figure 7.

The broad, flat valley floor formed by a meandering streamis called a floodplain. When a stream floods, it often will coverpart or all of the floodplain.


Figure 7 A meander is a broadbend in a river or stream. As timepasses, erosion of the outer bankincreases the bend.

Figure 8

VISUALIZING STREAM DEVELOPMENT

A lthough no two streams are exactly alike, all go through three main stages—young, mature, and old—as they flow from higher to lower ground. A youngstream, below, surging over steep terrain, moves rapidly. In a less steep land-

scape, right, a mature stream flows more smoothly. On nearly level ground, thestream–considered old–winds leisurely through its valley.The various stages of astream’s development are illustrated here.

Rapids

A young stream begins at asource—here, a melting mountainglacier. From its source, the streamflows swiftly downhill, cutting a narrow valley.

A

Waterfall


(inset)CORBIS/PictureQuest, (bkgd)Stephen R. Wagner


A mature stream flows smoothlythrough its valley. Mature streams oftendevelop broad curves called meanders.

B

Old streams flow through broad, flat floodplains.Near its mouth, the stream gradually drops its loadof silt. This sediment forms a delta, an area of flat,fertile land extending into the ocean.

C

Oxbowlake

(l)Harald Sund/The Image Bank/Getty Images, (r)Loren McIntyre


Old Streams The last stage in the development of a stream isthe old stage. An old stream flows smoothly through a broad,flat floodplain that it has deposited. South of St. Louis, Missouri,the lower Mississippi River is in the old stage.

Major river systems, such as the Mississippi River, usuallycontain streams in all stages of development. In the upstreamportion of a river system, you find whitewater streams movingswiftly down mountains and hills. At the bottom of mountainsand hills, you find streams that start to meander and are in themature stage of development. These streams meet at the trunkof the drainage basin and form a major river.

How do old streams differ from young streams?

Too Much WaterSometimes heavy rains or a sudden melting of snow can

cause large amounts of water to enter a river system. What hap-pens when a river system has too much water in it? The waterneeds to go somewhere, and out and over the banks is the only

choice. A river that overflows its bankscan bring disaster by flooding homesor washing away bridges or crops.

Dams and levees are built in anattempt to prevent this type of flood-ing. A dam is built to control the waterflow downstream. It may be built ofsoil, sand, or steel and concrete. Leveesare mounds of earth that are builtalong the sides of a river. Dams andlevees are built to prevent rivers fromoverflowing their banks. Unfortu-nately, they do not stop the water whenflooding is great. This was the case in1993 when heavy rains caused theMississippi River to flood parts of ninemidwestern states. Flooding resulted inbillions of dollars in property damage.Figure 9 shows some of the damagecaused by this flood.

As you have seen, floods can causegreat amounts of damage. But at cer-tain times in Earth’s past, great floodshave completely changed the surface ofEarth in a large region. Such floods arecalled catastrophic floods.

Figure 9 Flooding causes prob-lems for people who live alongmajor rivers. Floodwater brokethrough a levee during theMississippi River flooding in 1993.

Topic: Classificationof RiversVisit fl6.msscience.com for Weblinks to information about majorrivers in the United States. Classifytwo of these streams as young,mature, or old.

Activity Write a paragraphabout why you think the ColoradoRiver is a young, mature, or oldstream.

LA.B.2.3.4

LA.B.2.3.1

C. Davidson/Comstock



Catastrophic Floods During Earth’s long history, many cat-astrophic floods have dramatically changed the face of the sur-rounding area. One catastrophic flood formed the ChanneledScablands in eastern Washington State, shown above in Figure 10.A vast lake named Lake Missoula covered much of westernMontana. A natural dam of ice formed this lake. As the dammelted or was eroded away, tremendous amounts of water sud-denly escaped through what is now the state of Idaho intoWashington. In a short period of time, the floodwater removedoverlying soil and carved channels into the underlying rock,some as deep as 50 m. Flooding occurred several more times asthe lake refilled with water and the dam broke loose again.Scientists say the last such flood occurred about 13,000 years ago.

Deposition by Surface Water As water moves throughout a river system, it loses some of

its energy of motion and slows down. The water can no longercarry some of its sediment. As a result, it drops the sediment tothe bottom of the stream. The droping of sediment when wateror another agent of erosion loses energy is called deposition.

Some stream sediment is carried only a short distance. Infact, sediment often is deposited within the stream channel.Other stream sediment is carried great distances before beingdeposited. Sediment picked up when rill and gully erosion occuris an example of this. Water usually has a lot of energy as itmoves down a steep slope. When water begins flowing on a levelsurface, it slows, loses energy, and deposits its sediment. Wateralso loses energy and deposits sediment when it empties into anocean or lake.

Figure 10 The Channeled Scablandsformed when Lake Missoula drainedcatastrophically. WASHINGTON

OREGON

MONTANA

GlacialLake Missoula

Ice dam

Ice sheet

ChanneledScablands

CANADA

IDAHO

Casc

ade

Rang

e

0 100 km0 100 miles

These channels were formed bythe floodwaters.

Observing RunoffCollectionProcedure1. Complete a safety

worksheet.2. Put a plastic graduated

cylinder into a heavydrinking glass and placethe glass in the sink.

3. Fill a plastic sprinkling canwith water.

4. Hold the sprinkling canone-half meter above thesink and sprinkle wateronto the cylinder for 30 s.

5. Record the amount ofwater in the cylinder.

6. After emptying the cylin-der, place a plastic funnelinto the cylinder and sprin-kle again for 30 s.

7. Record the amount ofwater in the cylinder.

AnalysisExplain how a small amountof rain falling on a drainagebasin can have a big effecton a river or stream.

SC.D.1.3.5

James L. Amos/CORBIS


Self Check1. Explain how the slope of an area affects runoff.

2. Compare and contrast rill and gully erosion.

3. Describe the three stages of stream development.

4. Think Critically How is a stream’s rate of flow relatedto the amount of erosion it causes? How is it related tothe size of the sediments it deposits?

SummaryRunoff

• Rainwater that doesn’t soak into the groundor evaporate becomes runoff.

• Slope of land and vegetation affect runoff.

Water Erosion

• Water flowing over the same slope causes rillsand gullies to form.

River System Development

• A drainage basin is an area of land from whicha stream or river collects runoff.

5. Compare and contrast the formation of deltas and alluvial fans.

Deltas and Fans Sediment that is deposited as water emp-ties into an ocean or lake forms a triangular, or fan-shaped,deposit called a delta, shown in Figure 11. When the river watersempty from a mountain valley onto an open plain, the depositis called an alluvial (uh LEW vee ul) fan. The Mississippi Riverexemplifies the topics presented in this section. Runoff causesrill and gully erosion. Sediment is picked up and carried into thelarger streams that flow into the Mississippi River. As theMississippi River flows, it cuts into its banks and picks up moresediment. Where the land is flat, the river deposits some of itssediment in its own channel. As the Mississippi enters the Gulfof Mexico, it slows, dropping much of its sediment and formingthe Mississippi River delta. In this way, seasonal layers of silt canprovide fresh nutrients for vegetation.

Figure 11 This satellite imageof the Nile River Delta in Egyptshows the typical triangular shape.The green color shows areas ofvegetation.

Agricultureis importanton the Nile Delta.

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SC.D.1.3.1

SC.D.1.3.1

SC.D.1.3.5

SC.D.1.3.1

(l)Wolfgang Kaehler, (r)Nigel Press/Stone/Getty Images


SECTION 2 Groundwater 363

Groundwater SystemsWhat would have happened if the spilled milk in Section 1

ran off the table onto a carpeted floor? It probably would havequickly soaked into the carpet. Water that falls on Earth can soakinto the ground just like the milk into the carpet.

Water that soaks into the ground becomes part of a system,just as water that stays above ground becomes part of a river sys-tem. Soil is made up of many small rock and mineral fragments.These fragments are all touching one another, as shown inFigure 12, but some empty space remains between them. Holes,cracks, and crevices exist in the rock underlying the soil. Waterthat soaks into the ground collects in these pores and emptyspaces and becomes part of what is called groundwater.

How much of Earth’s water do you think is held in the smallopenings in rock? Scientists estimate that 14 percent of all fresh-water on Earth exists as groundwater. This is almost 30 timesmore water than is contained in all of Earth’s lakes and rivers.

Groundwater

■ Recognize the importance ofgroundwater.

■ Describe the effect that soil androck permeability have ongroundwater movement.

■ Explain how groundwater dis-solves and deposits minerals.

The groundwater system is animportant source of your drinkingwater.

Soil or rock fragment

Pore space

Water

Figure 12 Soil has many small,connected pores that are filledwith water when soil is wet.


Also covers: SC.D.1.3.3 (pp. 363–368), SC.H.1.3.5 Annually Assessed (p. 364)

Review Vocabularypore: a small, or minute, openingin rock or soil

New Vocabulary

• groundwater • water table

• permeable • spring

• impermeable • geyser

• aquifer • cave

First Image

Permeability A groundwater system is similar to a river sys-tem. However, instead of having channels that connect differentparts of the drainage basin, the groundwater system has con-necting pores. Soil and rock are permeable (PUR mee uh bul) ifthe pore spaces are connected and water can pass through them.Sandstone is an example of a permeable rock.

Soil or rock that has many large, connected pores is perme-able. Water can pass through it easily. However, if a rock or sed-iment has few pore spaces or they are not well-connected, thenthe flow of groundwater is blocked. These materials are imper-meable, which means that water cannot pass through them.Granite has few or no pore spaces at all. Clay has many smallpore spaces, but the spaces are not well-connected.

How does water move through permeable rock?

Groundwater Movement How deep into Earth’s crust doesgroundwater go? Figure 13 shows a model of a groundwater sys-tem. Groundwater keeps going deeper until it reaches a layer ofimpermeable rock. When this happens, the water stops movingdown. As a result, water begins filling up the pores in the rocksabove. A layer of permeable rock that lets water move freely is anaquifer (AK wuh fur). The area where all of the pores in the rockare filled with water is the zone of saturation. The upper surfaceof this zone is the water table.


Figure 13 A stream’s surfacelevel is the water table. Below thatis the zone of saturation.

Measuring Pore SpaceProcedure1. Use two identical, clear-

plastic containers.2. Put 3 cm of sand in one

container and 3 cm ofgravel in the other.

3. Pour water slowly into thecontainers and stop whenthe water just covers thetop of the sediment.

4. Record the volume ofwater used in each.

AnalysisWhich substance has morepore space—sand or gravel?

SC.D.1.3.5SC.H.1.3.5

Water TableWhy are the zone of saturation and the water table so impor-

tant? An average United States resident uses about 626 L of waterper day. That’s enough to fill nearly two thousand soft-drinkcans. Many people get their water from groundwater throughwells that have been drilled into the zone of saturation. However,the supply of groundwater is limited. During a drought, thewater table drops. This is why you should conserve water.


Calculate Rate of Flow

1. The groundwater in an aquifer flows at a rate of 0.5 m/day. How far does the groundwatermove in a year?

2. How long does it take groundwater in the above aquifer to move 100 m?

GROUNDWATER FLOW You and your family are hiking andthe temperature is hot. You feel as if you can’t walk onestep farther. Luckily, relief is in sight. On the side of anearby hill you see a stream, and you rush to splash somewater on your face. Although you probably feel that it’staking you forever to reach the stream, your pace is quickwhen compared to how long it takes groundwater to flowthrough the aquifer that feeds the stream. The followingproblem will give you some idea of just how slowlygroundwater flows through an aquifer.

The groundwater flows at a rate of 0.6 m/day. You’verun 200 m to get some water from a stream. How long doesit take the groundwater in the aquifer to travel the same distance?

SolutionThis is what you know:

This is what you want to find:

This is the equation you use:

Solve the equation for t andthen substitute known values:

● the distance that the groundwater has to travel:d � 200 m

● the rate that groundwater flows through theaquifer: r � 0.6 m/day

time � t

r � t � d (rate � time � distance)

t � � � 333.33 days (200 m)

��(0.6 m/day)

d�r

For more practice, visit fl6.msscience.com

Math Practice

MA.D.2.3.1

MA.D.2.3.1

CORBIS


Wells A good well extends deep into the zone of saturation,past the top of the water table. Groundwater flows into the well,and a pump brings it to the surface. Because the water tablesometimes drops during very dry seasons, even a good well cango dry. Then time is needed for the water table to rise, eitherfrom rainfall or through groundwater flowing from other areasof the aquifer.

Where groundwater is the main source of drinking water, thenumber of wells and how much water is pumped out are impor-tant. If a large factory were built in such a town, the demand onthe groundwater supply would be even greater. Even in times ofnormal rainfall, the wells could go dry if water were taken out ata rate greater than the rate at which it can be replaced.

In areas where too much water is pumped out, the land levelcan sink from the weight of the sediments above the now-emptypore spaces. Figure 14 shows what occurred when too muchgroundwater was removed in a region of California.

One type of well doesn’t need a pump to bring water to thesurface. An artesian well is a well in which water rises to the sur-face under pressure. Artesian wells are less common than othertypes of wells because of the special conditions they require.

As shown in Figure 15, the aquifer for an artesian well needsto be located between two impermeable layers that are sloping.Water enters at the high part of the sloping aquifer. The weightof the water in the higher part of the aquifer puts pressure onthe water in the lower part. If a well is drilled into the lower partof the aquifer, the pressurized water will flow to the surface.Sometimes, the pressure is great enough to force the water intothe air, forming a fountain.

How does water move through permeable rock?

Figure 14 The years on the poleshow how much the ground leveldropped in the San Joaquin Valley,California, between 1925 and1977.

Figure 15 The pressure of waterin a sloping aquifer keeps an arte-sian well flowing. Describe what limits how highwater can flow in an artesian well.

366 CHAPTER 12 Water Erosion and Depositionfile photo

Springs In some places, the water table is so close to Earth’ssurface that water flows out and forms a spring. Springs arefound on hillsides or other places where the water table meets asloping surface. Springs often are used as a source of freshwater.

The water from most springs is a constant, cool temperaturebecause soil and rock are good insulators and protect thegroundwater from changes in temperature on Earth’s surface.However, in some places, magma rises to within a few kilome-ters of Earth’s surface and heats the surrounding rock.Groundwater that comes in contact with these hot rocks isheated and can come to the surface as a hot spring.

Geysers When water is put into a teakettle to boil, it heatsslowly at first. Then some steam starts to come out of the cap onthe spout, and suddenly the water starts boiling. The teakettlestarts whistling as steam is forced through the cap. A similarprocess can occur with groundwater. One of the places wheregroundwater is heated is in Yellowstone National Park inWyoming. Yellowstone has hot springs and geysers. A geyser is ahot spring that erupts periodically, shooting water and steaminto the air. Groundwater is heated to high temperatures, causingit to expand underground. This expansion forces some of thewater out of the ground, taking the pressure off the remainingwater. The remaining water boils quickly, with much of it turn-ing to steam. The steam shoots out of the openinglike steam out of a teakettle, forcing the remainingwater out with it. Yellowstone’s famous geyser, OldFaithful, pictured in Figure 16, shoots between14,000 and 32,000 L of water and steam into the airabout once every 80 min.

The Work of GroundwaterAlthough water is the most powerful agent of

erosion on Earth’s surface, it also can have a greateffect underground. Water mixes with carbon diox-ide gas to form a weak acid called carbonic acid.Some of this carbon dioxide is absorbed from the airby rainwater or surface water. Most carbon dioxideis absorbed by groundwater moving through soil.One type of rock that is dissolved easily by this acidis limestone. Acidic groundwater moves throughnatural cracks and pores in limestone, dissolving therock. Gradually, the cracks in the limestone enlargeuntil an underground opening called a cave isformed.

Figure 16 Yellowstone’s famousgeyser, Old Faithful, used to eruptonce about every 76 min. An earth-quake on January 9, 1998, slowedOld Faithful’s “clock” by 4 min to anaverage of one eruption aboutevery 80 min. The average heightof the geyser’s water is 40.5 m.


Acid Rain Effects Acidrain occurs when gasesreleased by burning oil andcoal mix with water in theair. Infer what effect acidrain can have on a statuemade of limestone.

LA.B.2.3.1

Barbara Filet


Self Check1. Describe how the permeability of soil and rocks affects

the flow of groundwater.

2. Describe why a well might go dry.

3. Explain how caves form.

4. Think Critically Why would water in wells, geysers,and hot springs contain dissolved materials?

SummaryGroundwater Systems

• Water that soaks into the ground and collectsin pore spaces is called groundwater.

• 14 percent of all freshwater on Earth exists asgroundwater.

• Groundwater systems have connecting pores.

• The zone of saturation is the area where allpores in the rock are filled with water.

Water Table

• The supply of groundwater is limited.

5. Compare and contrast wells, geysers, and hot springs.

Cave Formation You’ve probably seen apicture of the inside of a cave, like the oneshown in Figure 17, or perhaps you’ve vis-ited one. Groundwater not only dissolveslimestone to make caves, but it also canmake deposits on the insides of caves.

Water often drips slowly from cracks inthe cave walls and ceilings. This water con-tains calcium ions dissolved from the lime-stone. If the water evaporates while hangingfrom the ceiling of a cave, a deposit of cal-cium carbonate is left behind. Stalactitesform when this happens over and over.Where drops of water fall to the floor of thecave, a stalagmite forms. The words stalac-tite and stalagmite come from Greek wordsthat mean “to drip.”

Sinkholes If underground rock is dis-solved near the surface, a sinkhole mayform. A sinkhole is a depression on the sur-face of the ground that forms when the roof

of a cave collapses or when material near the surface dissolves.Sinkholes are common features in places like Florida andKentucky that have lots of limestone and enough rainfall to keepthe groundwater system supplied with water. Sinkholes cancause property damage if they form in a populated area.

In summary, when rain falls and becomes groundwater, itmight dissolve limestone and form a cave, erupt from a geyser,or be pumped from a well to be used at your home.

Figure 17 Water dissolves rockto form caves and also depositsmaterial to form spectacular for-mations, such as these in CarlsbadCaverns in New Mexico.

More Section Review fl6.msscience.com

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The ShorePicture yourself sitting on a beautiful, sandy beach like the

one shown in Figure 18. Nearby, palm trees sway in the breeze.Children play in the quiet waves lapping at the water’s edge. It’shard to imagine a place more peaceful. Now, picture yourself sit-ting along another shore. You’re on a high cliff watching wavescrash onto boulders far below. Both of these places are shore-lines. An ocean shoreline is where land meets the ocean.

The two shorelines just described are different, even thoughboth experience surface waves, tides, and currents. These actionscause shorelines to change constantly. Sometimes you can seethese changes from hour to hour. Why are shorelines so differ-ent? You’ll understand why they look different when you learnabout the forces that shape shorelines.

Ocean Shoreline

■ Identify the different causes ofshoreline erosion.

■ Compare and contrast differenttypes of shorelines.

■ Describe some origins of sand.

Constantly changing shorelinesimpact the people who live andwork by them.

Shoreline

Sediment transport

Longshorecurrent

Figure 18 Waves, tides, and currents cause shorelinesto change constantly. Waves approaching the shorelineat an angle create a longshore current.

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Also covers: SC.D.1.3.3 (pp. 369–372), SC.H.1.3.4 Annually Assessed (p. 373), SC.H.1.3.5 AnnuallyAssessed (pp. 374–375)

Review Vocabularyspring tide: the tide of

increased range that occurs twicemonthly at the new and fullphases of the Moon

New Vocabulary

• longshore current

• beach

FCAT Vocabulary


Shoreline Forces When waves constantly pound against theshore, they break rocks into smaller and smaller pieces. Currentsmove many metric tons of sediment along the shoreline. Thesediment grains grind against each other like sandpaper. Thetide goes out carrying sediment to deeper water. When the tidereturns, it brings new sediment with it. These forces are alwaysat work, slowly changing the shape of the shoreline. Water isalways in motion along the shore.

The three major forces at work on the shoreline are waves,currents, and tides. Winds blowing across the water make waves.Waves, crashing against a shoreline, are a powerful force. Theycan erode and move large amounts of material in a short time.Waves usually collide with a shore at slight angles. This creates alongshore current of water that runs parallel to the shoreline.Longshore currents, shown in Figure 18, carry many metrictons of loose sediments and act like rivers of sand in the ocean.

How does a longshore current form?

Tides create currents that move at right angles to the shore.These are called tidal currents. Outgoing tides carry sedimentsaway from the shore, and incoming tides bring new sedimentstoward the shore. Tides work with waves to shape shorelines.You’ve seen the forces that affect all shorelines. Now you will seethe differences that make one shore a flat, sandy beach andanother shore a steep, rocky cliff.

Rocky ShorelinesRocks and cliffs are the most

common features along rockyshorelines like the one in Figure 19.Waves crash against the rocks andcliffs. Sediments in the water grindagainst the cliffs, slowly wearing therock away. Then rock fragmentsbroken from the cliffs are groundup by the endless motion of waves.They are transported as sedimentby longshore currents.

Softer rocks become erodedbefore harder rocks do, leavingislands of harder rocks. This takesthousands of years, but rememberthat the ocean never stops. In a sin-gle day, about 14,000 waves crashonto shore.

Figure 19 Along a rocky shore-line, the force of pounding wavesbreaks rock fragments loose, thengrinds them into smaller andsmaller pieces.

Macduff Everton/The Image Bank/Getty Images

Sandy BeachesSmooth, gently sloping shorelines are different from steep,

rocky shorelines. Beaches, the main feature of these shorelines,are deposits of sediment that are parallel to the shore.

Beaches can be made from different materials. Some aremade of rock fragments from the shoreline. Many beaches con-sist of grains of quartz, and others consist of seashell fragments.These fragments range in size from stones larger than your handto fine sand. Sand grains range from 0.06 mm to 2 mm in diam-eter. Why do many beaches have particles of this size? Wavesbreak rocks and seashells down to sand-sized particles like thoseshown in Figure 20. The constant wave motion bumps sandgrains together. This bumping not only breaks particles intosmaller pieces but also smooths off their jagged corners, makingthem more rounded.

How do waves affect beach particles?

Sand in some places is made of other things. For example,Hawaii’s black sands are made of basalt, and its green sands aremade of the mineral olivine. Jamaica’s white sands are made ofcoral and shell fragments.

Figure 20 Many people arefamiliar with quartz sand.However, beach sand can vary insize, color, and composition.Sometimes beach sand can beblack, white, tan, red, and evengreen.Explain why beaches are differentcolors.

SECTION 3 Ocean Shoreline 371

This Florida beachconsists primarily ofseashell fragments.

Some Hawaiianbeaches are composedof black basalt sand.

(tl)David Muench/CORBIS, (tr)SuperStock, (bl)Robert Holmes/CORBIS, (br)Breck P. Kent/Earth Scenes

Self Check1. Identify major forces that cause shoreline erosion.

2. Compare and contrast the features you would findalong a steep, rocky shoreline with the features youwould find along a gently sloping, sandy shoreline.

3. Explain how the type of shoreline could affect the typesof sediments you might find there.

4. List several materials that beach sand might be com-posed of. Where do these materials come from?

5. Think Critically How would erosion and deposition ofsediment along a shoreline be affected if the longshorecurrent was blocked by a wall built out into the water?

SummaryThe Shore

• An ocean shoreline is where land meets theocean.

• The forces that shape shorelines are waves,currents, and tides.

Rocky Shorelines

• Rocks and cliffs are the most common fea-tures along rocky shorelines.

Sandy Beaches

• Beaches are made up of different materials.Some are made of rock fragments and othersare made of seashell fragments.

Sand Erosion and Deposition

• Longshore currents, storms, and wind movesand.

• Beaches are fragile, short-term land features.

6. Solve One-Step Equations If 14,000 waves crash ontoa shore daily, how many waves crash onto it in a year? How many crashed onto it since you were born?

Sand Erosion and DepositionLongshore currents carry sand along beaches

to form features such as barrier islands, spits, andsandbars. Storms and wind also move sand.Thus, beaches are fragile, short-term land fea-tures that are damaged easily by storms andhuman activities such as some types of construc-tion. Communities in widely separated placessuch as Long Island, New York; Malibu, Cali-fornia; and Padre Island, Texas, have problemsbecause of beach erosion.

Barrier Islands Barrier islands are sand de-posits that lay parallel to the shore but are sepa-rated from the mainland. These islands startas underwater sand ridges formed by breaking

waves. Hurricanes and storms add sediment to them, raisingsome to sea level. When a barrier island becomes large enough,the wind blows the loose sand into dunes, keeping the new islandabove sea level. As with all seashore features, barrier islands areshort term, lasting from a few years to a few centuries.

The forces that build barrier islands also can erode them.Storms and waves carry sediments away. Beachfront develop-ment, as in Figure 21, can be affected by shoreline erosion.

Figure 21 Shorelines changeconstantly. Human development isoften at risk from shoreline erosion.

372 CHAPTER 12 Water Erosion and Deposition More Section Review fl6.msscience.com

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Classifying Types of Sand

LAB 373

Sand is made of different kinds of grains, butdid you realize that the slope of a beach isrelated to the size of its grains? The coarser thegrain size is, the steeper the beach is. The com-position of sand also is important.

Real-World ProblemWhat characteristics can be used to classify dif-ferent types of beach sand?

Goals■ Observe differences in sand.■ Identify characteristics of beach sand.■ Infer sediment sources.

Materialssamples of different sands (3)magnifying lens*stereomicroscopemagnet*Alternate materials

Safety PrecautionsComplete a safety worksheet before you begin.

Procedure1. Design a five-column data table to compare

the three sand samples. Use column one forthe samples and the others for the charac-teristics you will be examining.

2. Use the diagram in the previous column to determine the average roundness of eachsample.

3. Identify the grain size of your samples byusing the sand gauge above. To determinethe grain size, place sand grains in the middleof the circle of the sand gauge. Use the upperhalf of the circle for dark-colored particles andthe bottom half for light-colored particles.

4. Decide on two other characteristics to exam-ine that will help you classify your samples.

Conclude and Apply1. Compare and contrast some characteris-

tics of beach sand.

2. Describe why there are variations in thecharacteristics of different sand samples.

3. Explain what your observations tell youabout the sources of the three samples.

Compare your results with those of otherstudents.

0.25 0.5

0.25 0.5

0.1 1.0

0.1 1.0

Sand gauge(measurements in mm)

Angular Sub-angular

Sub-rounded

Rounded

Benchmark—SC.D.1.3.5: The student understands concepts of time and size relating tothe interaction of Earth’s processes; SC.H.1.3.4: The student knows that accurate recordkeeping, openness, and replication are essential to maintaining an investigator’s credi-bility with other scientists and society.

Real-World ProblemWhat would it be like to make a raft and use it to float on a river?Would it be easy? Would you feel like Tom Sawyer? Probably not.You’d be at the mercy of the current. Strong currents create fastrivers. But does fast moving water affect more than just floatingrafts and other objects? How does the speed of a stream or riveraffect its ability to erode?

Procedure1. Copy the data table on the following page.

2. Place the screen in the sink. Pour moist sand into your pan andsmooth out the sand. Set one end of the pan on the wood blockand hang the other end over the screen in the sink. Excess waterwill flow onto the screen in the sink.

3. Attach one end of the hose to the faucet and place the other endin the beaker. Turn on the water so that it trickles into the beaker.Time how long it takes for the trickle of water to fill the beaker tothe 1-L mark. Divide 1 L by your time in seconds to calculate thewater speed. Record the speed in your data table.

4. Without altering the water speed, hold the hose over the end ofthe pan that is resting on the wood block. Allow the water to flowinto the sand for 2 min. At the end of 2 min, turn off the water.

5. Measure the depth and length of the eroded channel formed bythe water. Count the number of branches formed on the channel.Record your measurements and observations in your data table.

Goals■ Assemble an appara-

tus for measuring theeffect of water speedon erosion.

■ Observe and mea-sure the ability ofwater traveling atdifferent speeds toerode sand.

Materialspaint roller pan*disposable wallpaper

trayssand 1-L beaker rubber tubing (20 cm)metric rulerwaterstopwatchfine-mesh screenwood block*Alternate materials

Safety Precautions

Complete a safety work-sheet before you begin.Wash your hands afteryou handle the sand.Immediately clean upany water that spills onthe floor.

Water Speed and Erosion


Benchmark—SC.D.1.3.1: The student knows that mechanical and chemical activitiesshape and reshape the Earth’s land surface by eroding rock and soil in some areas anddepositing them in other areas, sometimes in seasonal layers; SC.D.1.3.3: knows howconditions that exist in one system influence the conditions that exist in other systems;SC.D.1.3.5: understands concepts of time and size relating to the interaction of Earth’sprocesses; SC.H.1.3.5

--InquiryInquiry

KS Studios

6. Empty the excess water from the tray and smooth out the sand. Repeat steps 3through 5 two more times, increasing your water speed each time.

Conclude and Apply1. Identify the constants and variables in your experiment.

2. Observe Which water speed created the deepest and longest channel?

3. Observe Which water speed created the greatest number of branches?

4. Infer the effect that water speed has on erosion.

5. Predict how your results would have differed if one end of the pan had beenraised higher.

6. Infer how streams and rivers can shape Earth’s surface.

7. Predict how changing seasons might affect erosion and deposition.

LAB 375

Write a pamphlet for people buying homesnear rivers or streams that outlines thedifferent effects that water erosion couldhave on their property.

Water Speed and Erosion

Water Speed Depth of Channel Length of Channel

Number of(Liters per Second) Channel Branches

KS Studios

Do not write in this book.

Water levels are rising along the coastlineof the United States. Serious stormsand the building of homes and busi-

nesses along the shore are leading to the erosionof anywhere from 70 percent to 90 percent of theU.S. coastline. A report from the FederalEmergency Management Agency (FEMA) con-firms this. The report says that one meter ofUnited States beaches will be eaten away eachyear for the next 60 years. Since1965, the federal government hasspent millions of dollars replenish-ing more than 1,300 eroding sandyshores around the country. Andstill beaches continue to disappear.

The slowly eroding beachesare upsetting to residents andofficials of many communities,who depend on their shore toearn money from visitors. Somecity and state governments areturning to beach nourishment—a process in which sand is takenfrom the seafloor and dumped onbeaches. The process is expensive, however.The state of Delaware, for example, is spending7,000,000 dollars to bring in sand for its beaches.

Other methods of saving eroding beachesare being tried. In places along the Great Lakesshores and coastal shores, one company hasinstalled fabrics underwater to slow currents. Byslowing currents, sand is naturally deposited andkept in place.

Another shore-saving device is a syntheticbarrier that is shaped like a plastic snowflake.A string of these barriers is secured just offshore.

They absorb the energy of incom-ing waves. Reducing wave energycan prevent sand from beingeroded from the beach. New sandalso might accumulate becausethe barriers slow down the cur-rents that flow along the shore.

Many people believe that com-munities along the shore mustrestrict the beachfront building ofhomes, hotels, and stores. Sincesome estimates claim that by theyear 2025, nearly 75 percent of theU.S. population will live in coastalareas, it’s a tough solution. Says

one geologist, “We can retreat now and save ourbeaches or we can retreat later and probablyruin the beaches in the process.”

This beach housewill collapse as its

underpinnings are eroded.

Debate Using the facts in this article and other research youhave done in your school media center or through Web links atfl6.msscience.com, make a list of methods that could be used tosave beaches. Debate the issue with your classmates.

SCIENCEANDSocietySCIENCE ISSUES

THAT AFFECTYOU!

Is there hope for America’s coastlines or is beach erosion a “shore” thing?

For more information, visitfl6.msscience.com

LA.C.2.3.3LA.B.2.3.1LA.A.2.3.5

Gary Bogdon/CORBIS Sygma


Copy and complete the following concept map on caves.

Surface Water

1. Rainwater that does not soak into theground is pulled down the slope by gravity.This water is called runoff.

2. Runoff can erode sediment. Factors such assteepness of slope and number and type ofplants affect the amount of erosion. Rill,gully, and sheet erosion are types of surfacewater erosion caused by runoff.

3. Runoff generally flows into streams thatmerge with larger rivers until emptying intoa lake or ocean. Major river systems usuallycontain several different types of streams.

4. Young streams flow through steep valleysand have rapids and waterfalls. Maturestreams flow through gentler terrain andhave less energy. Old streams often are wideand meander across their floodplains.

Groundwater

1. When water soaks into the ground, itbecomes part of a vast groundwater system.

2. Although rock may seem solid, many typesare filled with connected spaces calledpores. Such rocks are permeable and cancontain large amounts of groundwater.

Ocean Shoreline

1. Ocean shorelines are always changing.

2. Waves and currents have tremendousamounts of energy which break up rocksinto tiny fragments called sediment. Overtime, the deposition and relocation ofsediment can change beaches, sandbars,and barrier islands.

CHAPTER STUDY GUIDE 377

Caves

dissolved by decorated by

which forms from

Carbon dioxide

Rock formations

hang from ceiling

build upfrom floor

Interactive Tutor fl6.msscience.com(l)Todd Powell/Index Stock, (r)J. Wengle/DRK Photo


Explain the difference between the vocabularywords in each of the following sets.

1. runoff—erosion

2. channel—drainage basin

3. aquifer—cave

4. spring—geyser

5. permeable—impermeable

6. erosion—deposition

7. groundwater—water table

8. permeable—aquifer

9. longshore current—channel

10. meander—channel

Choose the word or phrase that best answers thequestion.

11. Where are beaches most common?A) rocky shorelinesB) flat shorelinesC) aquifersD) young streams

12. What is the network formed by a river andall the smaller streams that contribute to it?A) groundwater systemB) zone of saturationC) river systemD) water table

13. Why does water rise in an artesian well?A) a pump C) heatB) erosion D) pressure

14. Which term describes rock through whichfluids can flow easily?A) impermeable C) saturatedB) meanders D) permeable

15. Identify an example of a structure createdby deposition.A) beach C) caveB) rill D) geyser

16. Which stage of development are mountainstreams in?A) young C) oldB) mature D) meandering

17. What forms as a result of the water tablemeeting Earth’s surface?A) meander C) aquiferB) spring D) stalactite

18. What contains heated groundwater thatreaches Earth’s surface?A) water table C) aquiferB) cave D) hot spring

19. What is a layer of permeable rock thatwater flows through?A) an aquifer C) a water tableB) a pore D) impermeable

20. Name the deposit that forms when amountain river runs onto a plain.A) subsidence C) infiltrationB) an alluvial fan D) water diversion

378 CHAPTER REVIEW

aquifer p. 364

beach p. 371

cave p. 367

channel p. 354

deposition p. 361

drainage basin p. 356

erosion p. 354

geyser p. 367

groundwater p. 363

impermeable p. 364

longshore current p. 370

meander p. 357

permeable p. 364

runoff p. 352

spring p. 367

water table p. 364

Vocabulary PuzzleMaker fl6.msscience.com

FCAT Vocabulary

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21. Concept Map Copy and complete the con-cept map below using the following terms:developed meanders, gentle curves, gentlegradient, old, rapids, steep gradient, widefloodplain, and young.

22. Describe what determines whether a streamerodes its bottom or its sides.

23. Interpret Data The rate of water flowing outof the Brahmaputra River in India, theLa Plata River in South America, and theMississippi River in North America aregiven in the table below. Infer which rivercarries the most sediment.

24. Explain why the Mississippi River hasmeanders along its course.

25. Outline Make an outline that explains thethree stages of stream development.

River Flow Rates

River Flow (m3/s)

Brahmaputra River, 19,800India

La Plata River, 79,300South America

Mississippi River, 175,000North America

26. Form Hypotheses Hypothesize why most ofthe silt in the Mississippi delta is foundfarther out to sea than the sand-sizedparticles are.

27. Infer Along what kind of shoreline wouldyou find barrier islands?

28. Explain why you might be concerned ifdevelopers of a new housing projectstarted drilling wells near your well.

29. Use Variables, Constants, and Controls Explainhow you could test the effect of slope onthe amount of runoff produced.

30. Poster Research a beach that interests you.Make a poster that shows different fea-tures you would find at a beach.

Performance Activities

CHAPTER REVIEW 379

Impermeablerock

Zone of saturation Water table

Permeablerock

Use the illustration below to answer questions

31 and 32.

31. Flow Distance The groundwater in an aquiferflows at a rate of 0.2 m/day. How far does thegroundwater move in one week?

32. Flow Time If groundwater in an aquifer flowsat a rate of 0.4 m/day, how long does it takegroundwater to move 24 m?

RiverSystems

Mature

Chapter Review fl6.msscience.com

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380 FLORIDA

a The Channeled Scablands in WashingtonState is an area covered by many deepchannels. The channels formed when alarge lake drained quickly. Which of thefollowing processes could cause a similararea to develop in Florida?

A. catastrophic flooding

B. chemical weathering

C. sediment deposition

D. sheet erosion

s The diagram below shows a formationthat often develops on slopes covered byloose soil and very little vegetation.

Which of the following best describes thistype of erosion?

F. sheet deposition

G. rill erosion

H. gully deposition

I. groundwater erosion

d Which best describes the effect of clearcutting the vegetation in a forest?

A. It results in less flooding in these areas.

B. It results in greater erosion in theseareas.

C. It results in less runoff into rivers inthese areas.

D. It results in greater amounts of rain-fall in these areas.

f A highway department is studying ways to improve state highways. The diagrambelow shows a cross section of one high-way studied. Side A has little vegetationand side B is planted with grass and otherplants.

Which can be inferred from the diagram?

F. Removing plants from roadsides willprotect the edges of the roads.

G. Highways with plants growing next tothem tend to have more traffic.

H. Planting seeds along a highway mayreduce erosion and repair costs.

I. Highways are more likely to beaffected by flooding if plants grownearby.

A B

FloridaFloridachapter chapter

The assessed Florida Benchmark appears above each question.Record your answers on the answer sheet provided by your teacher or on a sheet of paper.

FC

AT FOCUSF

C

AT FOCUS

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FACT PRACTICE 381FCAT Practice fl6.msscience.com

g Water moves at different rates in differentkinds of aquifers. Through which type ofrock is water likely to move the fastest?

A. marble, which has few or no pore spaces

B. limestone, which has many, well con-nected pore spaces

C. shale, which has small, poorly con-nected pore spaces

D. pumice, which has large, poorly con-nected pore spaces

h Which of the following would most likelytake the longest period of time to occur?

F. the development of a river

G. the runoff from a thunderstorm

H. the formation of a hurricane

I. the change from high and low tide

j Scientists sometimes use dye to study therate at which water flows in an aquifer.In one test, a dye was found to travel 28.2 kilometers in 3 days. At what rate,in kilometers per day, did the water in the aquifer flow?

k The diagram below shows a stream forma-tion seen in many rivers in Florida.

What stream formation does the diagramshow? Explain how differing speeds ofwater in a stream can cause this type ofstream formation.

l Carlos observed two different vacant lotsnear his school. He recorded what he sawin the table below.

PART A Compare and contrast the twolots.

PART B Describe the amount of runoffthat will occur on each lot.Explain your answer.

Characteristics of Two Vacant Lots

Lot Slope of lot Vegetation present

A Slight incline Grasses, shrubs, trees

B Steep incline Few trees

READINQUIREEXPLAIN

FCAT PracticeFCAT Practice FC

AT FOCUSF

C

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Double-Check Your Answer When you have finished eachquestion, reread your answer to make sure it is reasonable andthat it is the best answer to the question.

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