Why ItMatters CASESTUDY resources in Spanish. worksheets, multimedia,and resources, includinglabs, Go onlinetoaccessadditional Coastal Wetlands onpage74. Storm Surge, Tsunamis, and wetlands inthecasestudyThe services provided bycoastal abouttheimportant Learn life? observations directly affect your In whatwaysmightsatellite human impactontheplanet. increase ourknowledgeof health andairqualityto such thingsasecosystem enables scientiststodetermine Data from NASAsatellites The Hydrosphere and Biosphere Section 3 The Atmosphere Section 2 The Geosphere Section 1 Chapter 3 58 HMDScience.com EN Online Vir onmental Science Earth The Dynamic

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Section 1 The Geosphere Objectives Describe the composition and structure of Earth. Violent eruptions blow the tops off volcanoes, and molten rock from Earth’s interior flows across the surface of the planet. Hurricanes batter beaches and change Describe Earth’s tectonic plates. coastlines. Earthquakes shake the ground and topple buildings and freeway overpasses. All of these are the result of the dynamic state of planet Earth. What Explain the main cause of are the underlying conditions that cause our planet to change constantly? earthquakes and their effects.

Identify the relationship Earth as a System between volcanic eruptions and climate change. Earth consists of rock, air, water, and living things that all interact with each other. Scientists divide this system into four parts. As shown in Describe how wind and water Figure 1.1, the four parts are the geosphere (rock), the atmosphere (air), alter Earth’s surface. the hydrosphere (water), and the biosphere (living things). The solid part of Earth that consists of all rock, as well as the soils and loose rocks on Earth’s surface, makes up the geosphere. Most of Key Terms the geosphere is located in Earth’s interior. At the equator, the average geosphere distance through the center of Earth to the other side is 12,756 km. The atmosphere is the mixture of gases, nearly all of which are found in the hydro­sphere first 30 km above Earth’s surface. The hydro­sphere makes up all of the crust water on or near Earth’s surface. Much of this water is in the oceans. mantle Water is also found in the atmosphere, on land, and in the soil. The core biosphere is made up of parts of the geosphere, the atmosphere, and the lithosphere hydro­sphere. The biosphere is the part of Earth where life exists. It is a asthenosphere thin layer of living organisms found at Earth’s surface and extending from tectonic plate about 9 km above the surface down to the bottom of the ocean. chemical weathering erosion Figure 1.1

Earth As a System Earth is an integrated system that consists of the geosphere, the atmosphere, the hydrosphere, and the biosphere (inset).

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Discovering Earth’s Interior Studying the Earth beneath our feet is not easy. The deepest well that has been drilled into Earth’s interior is only about 12 km deep. An alternative method must be used to study the interior of Earth. Scientists can use seismic waves to learn about Earth’s interior. These waves travel through Earth’s interior during an earthquake. If you have ever tapped a melon to see if it is ripe, you know that the state of the melon’s interior affects the sound you detect. Similarly, a seismic wave is altered by the nature of the material through which it travels. As shown in Figure 1.2, seismologists measure changes in the speed and direction of seismic waves that pen- etrate the interior of the planet. By doing this, seismologists have learned that Earth is made up of dif­ferent layers and have inferred from the data what substances make up each layer.

The Composition of the Earth Scientists divide Earth into three layers—the crust, the mantle, and the core—based on their composition. These layers are composed of progres- sively denser materials toward the center of the Earth. Figure 1.3 shows a cross section of Earth. Earth’s thin crust is composed almost entirely of light elements. The crust makes up less than 1 percent of Earth’s mass. The crust is Earth’s thinnest layer. It averages about 5 km in thickness beneath the oceans and is 30 km to 35 km thick beneath the continents.

Figure 1.2

Seismic Waves Seismologists have measured changes in the speed and direction of seismic waves that travel through Earth’s interior. Through this process, they have learned that Earth is made up of different layers.

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Figure 1.3

Earth’s Layers Scientists divide Earth into different layers based on composition and physical properties.

The mantle, which is the layer beneath the crust, makes up 68 percent of the mass of Earth. The mantle is approximately 2,900 km thick and is made of rocks of medium density. Earth’s innermost layer is the core. The core, which has a radius of approximately 3,400 km, is composed of the elements having the greatest density.

The Structure of the Earth If we consider the physical properties of each layer, instead of their chemistry, Earth can be divided into five layers. Earth’s outer layer is the lithosphere. It is a cool, rigid layer, 15 km to 300 km thick, that includes the crust and uppermost part of the mantle. It is divided into huge pieces called tectonic plates. The asthenosphere is the layer beneath the lithosphere. The astheno­sphere is a pliable, solid layer of the mantle made of rock that flows very slowly and allows tectonic plates to move on top of it. Beneath the asthenosphere is the mesosphere, the lower part of the mantle. Earth’s outer core is a dense liquid layer. The inner core, at the center of Check for Understanding the Earth, is dense and solid, made up mostly of the metals iron and nickel. Identify Which of Earth’s physical layers The temperature of the inner core is estimated to be between 4,000°C to is liquid? 5,400°C. It is solid because it is under enormous pressure. Earth’s outer and inner core together make up about one-third of Earth’s mass.

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Figure 1.4

The Lithosphere Earth’s lithosphere is divided into pieces called tectonic plates. The tectonic plates are moving in different directions and at different speeds.

Eurasian plate North American plate

Indian plate Pacific plate African plate

Nazca South American plate plate Australian plate

Antarctic plate

Plate Tectonics The lithosphere is divided into pieces called tectonic plates that glide mg7vs_ear000014aa HMDScience.com 8th pass across the underlying asthenosphere in much the same way a chunk of 08/18/05 Tectonic Plate Boundaries ice drifts across a pond. The continents are located on the tectonic plates cmurphy and slowly, over eons, move around with them. The major plates include the Pacific, North American, South American, African, Eurasian, and Antarctic plates. Figure 1.4 illustrates the major tectonic plates.

Plate Boundaries Much of the geologic activity at the surface of Earth takes place at the boundaries between tectonic plates. Plates may move away from one another, collide with one another, or slip past one another. Enormous forces are generated at tectonic plate boundaries, where the crust is pulled apart, is squeezed together, or is slipping. The forces produced at the boundaries of tectonic plates can cause violent changes.

Plate Tectonics and Mountain Building When tectonic plates collide, the crust becomes thicker, is pushed up, buckles and folds, and eventually forms a mountain range. As shown in Figure 1.5, the Himalaya Mountains in south-central Asia began to form when the Eurasian tectonic plate and the Indian tectonic plate began to push into each other about 50 million years ago.

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©Jock Montgomery/Bruce Coleman, Inc./Photoshotot Earthquakes Figure 1.6 Earthquake Zones plate boundaries. North plate American andthePacific plate are slipping past oneanother. the entire length ofCalifornia. The San Andreas fault iswhere ofthe parts quakes have occurred along theSan Andreas fault, almost which runs boundaries. thepast Over 15millionto 20millionyears, many- earth Figure 1.6 Areas where oftheworld are occur earthquakes shownonthemap in Where DoEarthquakesOccur? widespread damage have magnitudes of7.0andgreater. the energyofmagnitude ofanearthquake that 5.0.Earthquakes cause below it. For example, ofmagnitude anearthquake 6.0releases 30times cates therelease ofabout 30timesmore energy than thewholenumber recorded is9.5.Each increase ofmagnitude by onewholenumber indi- felt isapproximately 2.0,andthelargest magnitude that has ever been iscalledan earthquake magnitude. The smallest magnitude that can be ergy released by anearthquake. The measure oftheenergy released by that cause widespread damage. them. are Otherearthquakes movements enormous oftheEarth’s crust are allthetime, occurring but many are small so that cannot we feel caused by slippage along afault are knownasearthquakes . Earthquakes a fault, ofvibrations aseries off. isset Thesevibrations ofEarth’s crust tive to oneanother. rocks When that are understress suddenly slip along A faultisabreak inEarth’s along whichslide crust blocksrela ofthecrust - The Richterby scale isused scientists to quantify theamount ofen- . The majority take ofearthquakes place at ornearplate tectonic The largestandmostactiveearthquakezonesliealongtectonic The DynamicEarth Chapter 3: of anearthquake? Explain Figure 1.5 containing Indiacontinueto collide. containing Asia andthetectonicplate because thetectonicplates Mountains arestillgrowingtoday Plate Collisions Che ismeantbythemagnitude What

c k f o r Understanding The Himalaya 63 Connect to BIOLOGY

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Connect to BIOLOGY Earthquake Hazard Can Animals Predict Despite much study, scientists cannot predict when earthquakes will take Earthquakes? place. However, information about where they are most likely to occur Can animals that live close to the site can help people prepare for them. An area’s earthquake-hazard level of an earthquake detect changes in is determined by past and present seismic activity. The Maps in Action their physical environment prior to an activity located at the end of this chapter shows earthquake-hazard levels earthquake? Documentation of unusual for the contiguous United States. animal behavior prior to earthquakes Earthquakes are not restricted to high-risk areas. In 1886, an can be found as far back as 373 BCE. earthquake shook Charleston, South Carolina, which is considered to Examples of this odd behavior include be in a medium-risk area. Because the soil beneath the city is sandy, zoo animals refusing to enter shelters this earthquake caused extensive damage. During shaking from a strong at night, snakes and small mammals earthquake, sand can act like a liquid and causes buildings to sink. abandoning their burrows, and wild Earthquake-resistant buildings are slightly flexible so that they can sway birds leaving their usual habitats. These behaviors reportedly happened with the ground motion. This flexibility can greatly reduce damages. within a few days, hours, or minutes of earthquakes. Volcanoes A volcano is a mountain built when magma—melted rock—rises from Earth’s interior to its surface. Once the magma reaches the surface, it is known as lava. Volcanoes are often located near tectonic plate boundaries where plates are either colliding or separating from one another. Volcanoes may occur on land or under the sea, where they may eventually break the ocean surface as islands. As Figure 1.7 shows, the majority of the world’s active volcanoes on land are located along tectonic plate boundaries that surround the Pacific Ocean.

Figure 1.7

The Ring of Fire Tectonic plate boundaries are places where volcanoes usually form. The Ring of Fire contains nearly 75 percent of the world’s active volcanoes that are on land. A large number of people live on or near the Ring of Fire.

critical thinking Explain Many of the islands in the central Pacific Ocean are of volcanic origin. Explain how they formed. PACIFIC OCEAN

Ring of Fire Plate boundary Volcano

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©Gary Braasch/Corbis Figure 1.8 Sixty-three peoplelosttheirlives, and596km Mount St.Helens that blewawaythetop410mofvolcano. degree Celsius over a period of several years. As a result, the average global temperature dropped by several tenths of a reached Earth’s surface was estimated to have decreased by 2 to 4 percent. eruption of Mount Pinatubo in the Philippines, the amount of sunlight that can cause a drop in the average global surface temperature. In the 1991 amount of sunlight that reaches Earth’s surface. This reduction in sunlight sphere. As the ash and gases spread across the planet, they can reduce the clouds of volcanic ash and sulfur-rich gases may reach the upper atmo in Major volcanic eruptions, such as the eruption of Mount St. Helens shown Global Effects ofVolcanic Eruptions difficulties. breathing cause Volcanicalso may ash vehicles. of engines the damage and crops, bury weight, its under collapse to buildings cause can ground the to falls that ash addition, In mudflow. a produce and water with mix can ash volcanic eruption, an During path. their in thing every sear and km/h 160 to up of speeds at volcano a of slope the down flow can gases and dust, ash, hot of Clouds loss. human great cause can and economies local to devastating be can up.Volcanic eruptions builds never pressure the so time, the all them of out havelavaflowing volcanoes Some volcano. the of surface solid the open blows it that great so becomes inside magma the of pressure the when erupts volcano A Local Effects ofVolcanic Eruptions Figure

1.8, can change Earth’s climate for several years. In large eruptions, OnMay18, 1980, MountSt. Helensin Washington Stateerupted. 2 offorestweredestroyedinaneruption - - The DynamicEarth Chapter 3: 65 printcode=a DO NOT EDIT--Changes mustbemadethrough “File info” 66 Figure 1.9 produce spectacularlandformsonEarth’s surface. Forces ofErosion 4. 3. 2. 1. Section 1 Introduction toEnvironmental Science Unit 1: ReviewingMainIdeas surface. Describe can haveeruption ontheglobal climate. Describe their effects. Explain compositional layers into whichis divided. Earth Name and describe thephysicaland describe and the main cause and ofearthquakes Overlongperiodsoftime, erosioncan how andwater wind alter Earth’s alarge-scalethe effects volcanic Formative Assessment Weathering andErosion erosion weathering water, moving rocks around andchanging theirappearance. Earth’s iscontinually surface battered by andscoured wind by running the Earth. At theEarth’s surface, rocks are altered by otherforces. The Forces at plates oftectonic theboundaries rock bring of to thesurface transports thematerials elsewhere. wears downrocks,wears making astimepasses, themsmoother and Mountains inthewest. eastern United States are olderthan thejagged Rocky learn that therounded Appalachian Moun have onit. acted This knowledge geologists helped is, thelonger theforces ofweathering anderosion deep gorges into the landscape, as shown in of spectacular landforms. Over time, rivers can carve storms can erode coastlines to give rise to a variety matic changes on Earth’s surface. Waves from ocean Erosion by both rivers and oceans can produce dra Water Erosion water. rock around themhas eroded been by and/or wind pinnacles ofhard rock stand alonebecause thesofter tacular rock formations are where seen sometimes rocks, such asgranite, do. Inspec oftheworld, parts rocks, such assandstone, erode more easily than hard are examples of places where few plants grow. Soft anddeserts,Beaches which have loose, sandy soil, are fewplants, can blow wind away soil quickly. very roots inplace. holdsoil But inplaces where there scape of our planet. In places where plants grow, their Like moving water, can change also wind theland - Wind Erosion 6. 5. CriticalThinking mountain range andanoldmountain range. features you ayoung wouldassociate with From what you have read, thephysical describe oferosioneffects on mountains onthispage. Compare andContrast into plates? tectonic different be of theEarth ifitwere notdivided Analyzing Processes

The olderamountain range How might thesurface Read about the Chemical ­tains inthe Figure

1.9. - -

Image Credits: ©Dennis Flaherty/Photo Researchers, Inc. ©NOAA/Department of Commerce/NOAA Central Library U Composition ofthe Atmosphere Earth issurrounded byamixture ofgasesknownasthe The Atmosphere at whichlivingthingscansurvive. which theEarth’s surfacelosesheat.The­ A volcanic eruptionaddsgases.Avehiclebothandremoves gases. and removed from theatmosphere inwaysotherthanthrough livingorganisms. add oxygentotheatmosphere whentheyproduce food.Gasescanbeaddedto add carbondioxidewhentheybreathe out.Plantstakeincarbondioxideand example, animalsremove oxygenfrom theatmosphere whentheybreathe inand atmosphere changesconstantlyasthesegasesare addedandremoved. For oxygen, carbondioxide,andothergasesare allpartsofthismixture. Earth’s elevations ismore difficult. creases, breathing so at higher aselevationless dense in- tudes. Thebecomes airalso air decreases at higher alti- air downwards, theamount of gravity pulls of themolecules our planet’s surface. Because gases is located 30 km within of mass ofEarth’s atmospheric Earth’s surface. Most ofthe the atmosphere near isdenser As aresult ofthepull ofgravity, ward Earth’s by surface gravity. The atmosphere ispulled to- Air Pressure Figure 2.1 microscopic andliquiddroplets particles called aerosols. combustion, skin, hair, bitsofclothing, andviruses, bacteria pollen, and but includes salt, ashfrom fires, volcanic ash, particulate matter from particles,solid oratmospheric dust. Atmospheric dust ismainly soil dioxide, methane, and water vapor, make up the rest of the atmosphere. marily produced by plants and algae. Other gases, including argon, carbon cay. Oxygen, the second most abundant gas in Earth’s atmosphere, is pri atmosphere when volcanoes erupt and when dead plants and animals de Nitrogen makes up 78 percent of the Earth’s atmosphere. It enters the The atmosphere alsoinsulatesEarth’s surface.Thisinsulationslowstherateat In additionto gases, theatmosphere contains many oftiny, types shows the percentages of gases that make up Earth’s atmosphere. atmosphere keepsEarthattemperatures Figure 2.1 pressure, andwindspeed. Admini­ Physical andChemicalCompositionofthe Atmosphere

Nitrogen andoxygenmakeup99 percentofthecompositionthe atmosphere. Scientists onboardaresearchplanefromtheNationalOceanicand Atmospheric stration (NOAA)aremakingmeasurementsoftemperature, humidity, barometric atmosphere . Nitrogen, - - The DynamicEarth Chapter 3: 21% Oxygen Other 1% Explain thegreenhouseeffect. atmosphere. of heattransfer inEarth’s Explain three mechanisms atmosphere. Describe thelayers ofEarth’s Earth’s atmosphere. Describe thecompositionof greenhouse effect convection conduction radiation ozone stratosphere troposphere atmosphere Key Terms Section 2 Nitrogen 78% Objectives

67 Layers of the Atmosphere The atmosphere is divided into four layers based on temperature changes that occur at different distances above the Earth’s surface. Figure 2.3 shows the four layers of Earth’s atmosphere.

The Troposphere The atmospheric layer nearest Earth’s surface is the troposphere. The troposphere extends to about 18 km above Earth’s surface. Almost all of the weather occurs in this layer. The troposphere is Earth’s densest atmo- spheric layer. Temperature decreases as altitude increases in the tropo- sphere, as shown in Figure 2.3.

Pressure (Pa) 0 2.0 3 104 6.0 3 104 1.0 3 105 Figure 2.3

Atmospheric Layers The layers of the atmosphere differ in temperature 600 and pressure. 500

Thermosphere 100

90

80 Temperature 70 Mesosphere 60 Altitude (km)

50

40 Ozone layer

30 Stratosphere

Pressure 20

10 Troposphere 0 –80 –70 –60 –50 –40 –30 –20 –10 0 10 20 Temperature (˚C)

68 Unit 1: Introduction to Environmental Science Figure 2.4 Figure 2.5

The Tropopause This sunrise scene that was taken from space captures the tropopause, Auroras The aurora borealis, or the transitional zone that separates the troposphere (yellow layer) from the stratosphere (white Northern Lights, can be seen in the layer). The tropopause is the illuminated brown layer. skies around Earth’s North Pole.

ECOFACT

The Stratosphere Above the troposphere is the stratosphere. The stratosphere, separated from the troposphere by the tropopause, shown in Figure 2.4, extends from about 18 km to an altitude of about 50 km. Temperatures rise as altitude increases because ozone in the stratosphere absorbs the sun’s ultraviolet

(UV) energy and warms the air. Ozone, O3, is a molecule made up of three oxygen atoms. Almost all the ozone in the atmosphere is concentrated in the ozone layer in the stratosphere. Ozone reduces the amount of harm- ful UV radiation that reaches Earth.

The Mesosphere The layer above the stratosphere is the mesosphere. This layer extends ECOFACT to an altitude of about 80 km. The mesosphere is the coldest layer of the atmosphere. Its temperatures have been measured as low as -93°C. The Mesosphere In geology, the term mesosphere, which means “middle sphere,” The Thermosphere refers to the 2,550 km thick physical Farthest from Earth’s surface is the thermosphere. In the thermosphere, layer of the Earth that lies below the nitrogen and oxygen absorb solar radiation, resulting in temperatures asthenosphere. The mesosphere is also the name of the atmospheric above 2,000°C. Despite these high temperatures, the thermosphere would layer that extends from 50 to 80 km not feel hot to us. Air particles that strike one another transfer heat. The above Earth’s surface. air in the thermosphere is so thin that air particles rarely collide, so little heat is transferred. Nitrogen and oxygen atoms in the lower region of the thermosphere (about 80 km to 550 km above Earth’s surface) absorb harmful solar radiation, such as X rays and gamma rays. This absorption causes atoms to become electrically charged. Electri­cally charged atoms are called ions. Check for Understanding The lower thermosphere is called the ionosphere. Sometimes ions radiate Infer  How does ozone in the energy as light. This light often glows in spectacular colors in the night stratosphere affect life on the Earth’s

(tl) ©NASA; (tr) SPL/Photo Researchers, Inc. (tl) ©NASA; (tr) SPL/Photo Researchers, skies near the Earth’s North and South Poles, as shown in Figure 2.5. surface?

Chapter 3: The Dynamic Earth 69 QUICKLAB

Energy in the Atmosphere As shown in Figure 2.6, energy from the sun is transferred in Earth’s QUICKLAB atmosphere by three mechanisms: radiation, convection, and conduction. The Heat is On! Radiation is the transfer of energy across space and in the atmosphere. Procedure When you stand before a fire or a bed of coals, the warmth you feel has 1. Select 6 places in your classroom reached you by radiation. Conduction is the transfer of energy in the to measure the air temperature. form of heat from a warmer object to a colder object when the objects 2. Choose a spot near the ceiling, are placed in direct physical contact. Convection is the transfer of energy one near the floor, one near a because variations in temperature move the matter making up air. For dark-colored surface, one near a example, if you live in a colder climate, the heating vents in your home light-colored surface, and two other are probably on or near the floor, so that the house will warm as the air places, spaced around the room. rises upwards. 3. Write a hypothesis explaining why temperatures might vary from place to place within the room. Warming of the Atmosphere 4. Construct a data table to record Solar energy reaches Earth as electromagnetic radiation, which includes your measurements. visible light, infrared radiation, and ultraviolet light. Our planet only re- 5. Measure the temperatures (in °C) ceives about two-billionths of this energy. However, this seemingly small in all six areas. amount of radiation contains a tremendous amount of energy. As shown in Analysis Figure 2.6, about half of the solar energy that enters the atmosphere passes 1. How is energy being transferred through and reaches Earth’s surface. The rest is absorbed or reflected in the within the room? If more than one atmosphere by clouds, gases, and dust, or it is reflected by Earth’s surface. mechanism is a factor, explain. On a sunny day, rocks may become too hot to touch. If Earth’s surface 2. Explain the reasons behind any continually absorbed energy, it would get hotter and hotter. This does not differences you saw. happen, because the oceans and the land radiate some of the energy they have absorbed back into the atmosphere.

Figure 2.6

Thermal Radiation Three important mechanisms responsible for transferring energy in the atmosphere are radiation, conduction, and convection.

70 ECOFACT

You may have noticed that dark-colored objects become much hotter in the sun than light-colored objects. Dark-colored objects absorb more ECOFACT solar radiation than light-colored objects, so dark-colored objects have Lost Weekend more energy to release as heat. Because of the dark color of street and Doesn’t it always seems to rain on the parking lot services, the temperature in cities is higher than the tempera- weekends? If you live on the East Coast, ture in the surrounding countryside. that might actually be true. Researchers recently found that the mid-Atlantic states have a 30 to 40 percent greater The Movement of Energy in the Atmosphere chance of rain on the weekends than Air that is constantly moving upward, downward, or sideways causes other states. Why? Automobile exhaust Earth’s weather. In the troposphere, currents of less dense air, warmed by that accumulates in the atmosphere the Earth’s surface, rise into the atmosphere, and currents of denser cold over the course of the work week has air sink toward the ground. As a current of air rises into the atmosphere, caused weather patterns in this area it begins to cool and condense. The air current sinks instead of continu- to shift. By Friday, the levels of exhaust ing to rise. So, the air current moves back toward Earth’s surface until it particles are high enough to trigger rain. is warmed, becomes less dense, and begins to rise again. This continual process, called a convection current, moves the air in a circular pattern. A convection current can be seen in Figure 2.6. Check for Understanding Explain Why does cool air sink and warm air rise in the atmosphere? Solar Energy that Reaches Earth 20% absorbed by ozone, clouds, and 5% reected by atmospheric gases the Earth’s surface

25% scattered 50% absorbed by and reected by the Earth’s surface clouds and air

Chapter 3: The Dynamic Earth 71 Figure 2.7 The Greenhouse Effect The gases in the atmosphere act like a layer of glass. Both allow solar energy to pass through. But glass and some of the gases in the atmosphere absorb energy and stop the heat from escaping into space.

critical thinking Explain What is the relationship between the greenhouse effect and global climate change?

The Greenhouse Effect The gases in Earth’s atmosphere act like the glass in the car shown in Figure 2.7. Sunlight that penetrates Earth’s atmosphere warms the surface and lower atmosphere of the Earth. This process, in which greenhouse gases absorb and reradiate infrared radiation near the Earth, is known as the greenhouse effect. Without the greenhouse effect, the Earth would be too cold for life to exist. The gases in our atmosphere that trap heat are called greenhouse gases. None of these have a high concentration in Earth’s atmosphere. The most abundant greenhouse gases are water vapor, carbon dioxide, FieldStudy methane, and nitrous oxide. The amounts of these gases vary consider- Go to Appendix B to find the field study ably as a result of natural and industrial processes. Many scientists associ-

Detecting CO2 ate the addition of these gases from industry with global climate change.

Section 2 Formative Assessment

Reviewing Main Ideas Critical Thinking 1. Describe the composition of Earth’s atmosphere. 5. Analyzing Processes Write a paragraph that explains why Earth’s atmosphere becomes less 2. Describe a characteristic of each layer of the dense with increasing altitude above Earth. atmosphere. 6. Analyzing Processes How does human 3. Identify the three mechanisms of energy activity change some greenhouse-gas levels? transfer in Earth’s atmosphere. 4. Describe the role of greenhouse gases in Earth’s atmosphere.

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©Peter Wey/Fotolia The Hydrosphere and Water Cycle of therequirements ofalllivingthingsisliquidwater. called thebiosphere,everythingthatorganismsneedtosurvivecanbefound.One Life onEarthisrestricted toaverynarrow layeraround Earth’s surface.Inthislayer, Biosphere The Hydrosphere and Figure 3.1 The Water Cycle These larger droplets fall from clouds as rain in a process called which the droplets collide, stick together, and create larger,forms heavier water droplets droplets. on dust particles. These water Evaporation to water sources is known as the layers beneath Earth’s surface, andclouds. as thewater intheoceans, lakes, rivers, wetlands, icecaps, polar rock soil, The hydrosphere includes allofthewater onornear Earth’s surface, such evaporates from the oceans. In the process of from Earth’s oceans, lakes, streams, and soil, but the majoritythen ofrises the intowater the atmosphere as water vapor. Water continually evaporates Precipitation may also take the form of snow, sleet, or hail. condensation, and The continuous movement of water into the air, onto land, and then back cond pr e is the process by which liquid water is heated by the sun and cipitation e The major processes of the water cycle include nsation precipitation. water cycle , which is shown in condensation

e ­droplets form clouds, in vaporation evaporation, , water vapor Figure 3.1 precipitation . . The DynamicEarth Chapter 3: open andclosedsystems. Explain thedifference between life tothebiosphere. Discuss thefactorsthatconfine regulates Earth’s temperature. Explain how theocean currents. Describe thetwo typesofocean ocean water. Describe thepropertiesof processes inthewater cycle. Name thethree major biosphere fresh water salinity precipitation condensation evaporation cyclewater Key Terms Section 3 Objectives 73 Connect to GEOLOGY

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Connect to GEOLOGY Earth’s Oceans Submarine Volcanoes We talk about the Atlantic Ocean, the Pacific Ocean, the Arctic Ocean, the Geolo­gists estimate that approximately Southern Ocean, and the Indian Ocean. However, if you look at Figure 3.2, 80 percent of the volcanic activity on you see that these oceans are all joined. This single, large, interconnected Earth takes place on the ocean floor. body of water is called the world ocean. Its waters cover a little over 70 Most of this activity occurs as magma percent of the Earth’s surface. As we will see, the world ocean plays many slowly flows onto the ocean floor important roles in regulating our planet’s environment. where tectonic plates pull away from each other. But enormous undersea The largest ocean on Earth is the Pacific Ocean. It covers a surface volcanoes are also common. Off the area of approximately 155,557,000 km2 and has an average depth of coast of Hawaii, a submarine volcano 4,280 m. The deepest point on the ocean floor is in the Pacific Ocean. This called the Loihi Seamount rises 5,185 point is called the Challenger Deep and is located east of the Philippine­ m from the ocean floor. Loihi is just Islands at the bottom of the Mariana Trench and is deeper than Mount 915 m below the ocean’s surface, and Everest is tall. in several thousand years, this volcano The second-largest ocean on Earth is the Atlantic Ocean. It covers a may become the next Hawaiian Island. surface area of 76,630,000 km2, which is about half the area of the Pacific Ocean. Like the Pacific Ocean, the Atlantic Ocean can be divided into a north half and a south half based on the directions of surface current flow north and south of the equator.

CASESTUDY Storm Surge, Tsunamis, and Coastal Wetlands Coastal wetlands include mangrove forests and salt Saltmarsh cordgrass, shown in a salt marsh at the New marshes. These ecosystems filter the water, are a home for River Inlet, North Carolina, helps to anchor shorelines. many species, prevent erosion, and provide recreational and commercial opportunities for people. Coastal wetlands hurricanes or a tsunami may not travel as far. It also may are worth billions of dollars to the economy every year, but not be as powerful. Another way that wetlands provide in many areas of the world they have been removed for protection from disasters is by building up sediment and human development. holding it together. By creating more land and stable In the last several years major natural disasters have shorelines, the wetlands will reduce damage from waves shown how vulnerable coastal areas can be. Hurricane even more. Katrina along the Gulf of Mexico and tsunamis in Japan Multiple studies have found that the loss of human lives and southeast Asia killed thousands of people and resulted and livestock as well as the economic damage inflicted on in billions of dollars of damage. In these areas, many an area by hurricanes are less when they are protected coastal wetlands had been removed. Could mangrove by coastal wetlands. We know less about how wetlands forests or coastal marshes have reduced the damage? protect coastal communities from tsunamis, but one study The plants of coastal wetlands can reduce the height found that having coastal trees reduced the loss of human of waves, so the surge of water moving inland from life by 5%. ©Norm Thomas/Photo Researchers, Inc. Thomas/Photo Researchers, ©Norm

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Earth’s Oceans The Indian Ocean covers a surface area of Figure 3.2 73,762,000 km2 and is the third-largest ocean We talk about the Atlantic Ocean, the Pacific Ocean, the Arctic Ocean, the on Earth. It has an average depth of 3,890 m. World Ocean The Pacific, Atlantic, Indian, Southern, and Arctic Oceans are Southern Ocean, and the Indian Ocean. However, if you look at Figure 3.2, interconnected into a single body of water, the world ocean, which covers 70 In 2000, the waters that completely sur- you see that these oceans are all joined. This single, large, interconnected percent of Earth’s surface. round the continent of Antarctica were desig- body of water is called the world ocean. Its waters cover a little over 70 nated as the Southern Ocean. Although it has percent of the Earth’s surface. As we will see, the world ocean plays many no land mass to separate it from the others, it important roles in regulating our planet’s environment. can be distinguished by the rapid movement The largest ocean on Earth is the Pacific Ocean. It covers a surface of its waters around Antarctica, known as the area of approximately 155,557,000 km2 and has an average depth of Antarctic Circumpolar Current. It encom- 4,280 m. The deepest point on the ocean floor is in the Pacific Ocean. This passes an area of approximately 20,327,000 point is called the Challenger Deep and is located east of the Philippine­ km2. Islands at the bottom of the Mariana Trench and is deeper than Mount The smallest ocean is the Arctic Ocean, Everest is tall. which covers 14,560,000 km2. The Arctic The second-largest ocean on Earth is the Atlantic Ocean. It covers a Ocean is unique because much of its surface is surface area of 76,630,000 km2, which is about half the area of the Pacific SOUTHERN ­covered by floating ice. This ice, which is called OCEAN Ocean. Like the Pacific Ocean, the Atlantic Ocean can be divided into a pack ice, forms when either waves or wind north half and a south half based on the directions of surface current flow drive together frozen seawater, known as sea north and south of the equator. ice, into a large mass.

CASESTUDY

Over 80% of New Orleans was submerged by floodwater when Hurricane Katrina struck in August, 2005.

Not all types of coastal wetland will provide the same Many communities have decided that protecting amount of protection. For example, dense mangrove forests remaining coastal wetlands is not enough. They are working are better than those with fewer trees. Also, it is important to restoreCritical degraded Thinking wetlands or create new wetlands that wetlands are relatively large. The tsunami in the Indian where they have been destroyed. Scientists are working Ocean in 2004 and the oil from the Deepwater Horizon spill to find out the best ways to restore wetlands to provide in 2010 killed large areas of wetlands, but only in a strip many benefits including increasing tourism, increasing fish along the coast. The mangrove forests and marshes further populations, and protecting coastal communities. inland mostly survived and allowed the wetlands to remain largely intact. Even though coastal wetlands are a benefit during Critical Thinking natural disasters, they are not a substitute for other Explain A local city commission is trying to methods of protection, like early warning systems. Because decide what should be done with a large vacant wetlands provide many benefits other than reducing the area along the coast. Provide an argument why it impacts of natural disasters, it is important to preserve might be a good idea to create a coastal wetland. them. ©Vincent Laforet, POOL/AP Images ©Vincent Laforet,

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Figure 3.3 Ocean Water Dissolved Solids This pie graph shows the percentages by The difference between ocean water and fresh water weight of dissolved solids found in ocean water. Sodium and is that ocean water contains more salts. These salts chlorine, the two elements that form salt, are the most important have dissolved out of rocks on land and have been dissolved solids in ocean water. carried down rivers into the ocean over millions of Other 0.7% years. Underwater volcanic eruptions also add salts Potassium 1.1% to the ocean. Most of the salt in the ocean is sodium chloride, Calcium 1.2% Chlorine 55.0% which is made up of the elements sodium and chlo- Sulfur 3.7% rine. Figure 3.3 shows the concentration of these and other elements in ocean water. The salinity of ocean Magnesium 7.7% water is the concentration of all the dissolved salts it contains. The average salt content of ocean water is Sodium 30.6% 3.5 percent by weight. The salinity of ocean water is lower in places that get a lot of rain or in places where freshwater flows into the sea. Salinity is higher where water evaporates rapidly and leaves the salts behind.

Temperature Zones Figure 3.4 shows the temperature zones of the ocean. The surface of the ocean is warmed by the sun. In contrast, the depths of the ocean, where sunlight never reaches, have temperatures only slightly above freezing. HMDScience.com Surface waters are stirred up by waves and currents, so the warm surface Understanding Ocean zone may be as much as 350 m deep. Below the surface zone is the ther- Currents mocline, which is a layer about 300 to 700 m deep where the temperature falls rapidly with depth. From the bottom of the thermocline, down to the bottom of the ocean, lies the cold, dark deep zone.

Figure 3.4 Ocean Zones Water in the ocean can be divided into three zones based on temperature. 0 Surface Zone The surface zone is the warm, top layer of ocean water. Sunlight heats the top 200 100 m of the surface zone. Surface currents mix the heated water with cooler water below.

400

Thermocline Water temperature in this zone drops faster with increased depth 600 than it does in the other two zones. Water depth (m)

800 Deep Zone This bottom layer extends from the base of the thermocline to the 1,000 bottom of the ocean. The temperature in this zone averages 2C.

1,200 0 5 10 15 20 25 30 Water temperature (˚C)

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©Rosenstiel School of Marine & Atmospheric Science Figure 3.5 The GulfStream British IslesarewarmedbythewatersofGulfStream. water (showninred, orange, andyellow)fromlowerlatitudesintohigherlatitudes. The from lower latitudes toward higher latitudes, asshownin IslesBritish are by warmed theGulf Stream, which moves waters warm areas flow they past to have amore moderate climate. For example, the by Currents ocean. theworld that circulate water warm cause theland temperature extreme too wouldbe to exist. forlifeonEarth didnotregulateIf theocean temperatures, atmospheric andsurface the changes much more slowly than itwouldifthere were onEarth. noocean than land does. Asaconsequence, thetemperature oftheatmosphere planet’s surface. The absorbs both andreleases ocean heat more slowly energy from sunlight regulates temperatures inEarth’s atmosphere. store energy from sunlight. This capacity to oftheocean absorb andstore ofthemostisto ocean absorb important and functionsoftheworld One A GlobalT critical thinking Local temperaturesLocal indifferent areas oftheplanet are regulated also The absorbs ocean over world half radiation thesolar that reaches the what would to what happen the climate of the British Isles? Predict If cold from water melting polar ice were to shut the down Gulf Stream, emperature Regulator Inthisinfraredsatelliteimage, theGulfStreamismovingwarm Figure 3.5 . The DynamicEarth Chapter 3: land? by the absorptionandreleaseofheat bytheoceandifferfrom release ofheat doestheabsorptionand Compare How and Winnipeg? in degreesCelsiusbetweenPlymouth temperatures low difference inaverage and –20°CinFebruary. isthe What in December, –23°CinJanuary, of–18°C temperatures low average in theinteriorofNorth America, has February. Winnipeg, whichislocated December, 3°CinJanuary, and3°Cin of4°Cin temperatures low average England nearthe Atlantic Ocean, has inthesouthwest of is located 50° northlatitude. Plymouth, which Canada, approximately at arelocated Plymouth, England, and Winnipeg, bytheGulf Stream.is moderated The temp­ Stream The InfluenceoftheGulf C C Che o o n n n n c ec ec er­ k f a ­ture oftheBritishIsles t t o r Understanding t t o o

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QUICKLAB Ocean Currents Deep Ocean Currents Streamlike movements of water that occur at or near the surface of the Procedure ocean are called surface currents. Surface currents are wind driven and 1. Fill a large glass container or result from global wind patterns. Figure 3.6 shows the major surface cur- aquarium with hot water. rents of the world ocean. Surface currents may be warm-water currents 2. Next, fill a 100 mL beaker with very or cold-water currents. Currents of warm water and currents of cold water cold water, adding several drops of do not readily mix with one another. Therefore, a warm-water current like dark food coloring. the Gulf Stream can flow for hundreds of kilometers through cold water 3. Hypothesize an explanation for without mixing and losing its heat. what might happen when the cold Surface currents can influence the climates of land areas they flow water is added to the hot water. past. As we have seen, the Gulf Stream moderates the climate in the 4. Holding the beaker above the larger British Isles. The Scilly Isles in England are as far north as Newfoundland container, carefully pour the icy in northeast Canada. However, palm trees grow on the Scilly Isles, where it water into the hot water. never freezes, whereas Newfoundland has long winters of frost and snow. Analysis Deep currents are streamlike movements of water that flow very 1. What did you observe when the slowly along the ocean floor. Deep currents form when the cold, dense cold water was poured into the hot water from the poles sinks below warmer, less dense ocean water and water? flows toward the equator. The densest and coldest ocean water is located 2. Explain why this occurred and how off the coast of Antarctica. This cold water sinks to the bottom of the it relates to ocean currents. ocean and flows very slowly northward to produce a deep current called the Antarctic Bottom Water. The Antarctic Bottom Water creeps along the ocean floor for thousands of kilometers and reaches a northernmost point of approximately 40° north latitude. It takes several hundred years for water in this deep current to make this trip northward.

Figure 3.6

Surface Currents The oceans’ surface currents circulate in different directions in each hemisphere.

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©SPL/Photo Researchers, Inc. Groundwater Fresh Water United States. of aquifers inthecontiguous Figure 3.8 fer iscalled arecharge zone. where water enters anaqui- The oftheland surface water. iscalled anaquifer allows theflow ofground- A rock layer that stores and Aquifers than 1 percent ofallthewater on Earth. agricultural uses. andindustrial But groundwater accounts forless the human forfresh need water drinking andsupplies water formany through theground asgroundwater andcollects . Groundwater fulfills of thiswater ends upinstreams andrivers, but mostdown ofittrickles Rain andmelting snow sink into theground off theland. Some andrun andallitstributaries.river Asshownin system contains alloftheland drained by ariver, including themain systemA river isanetwork ofstreams that drains anarea ofland. Ariver River Systems 3 percent ofallthewater is onEarth Most ofthewater issalt water onEarth Alittle intheocean. more than covers about 40percent ofthecontiguous United States. eventually drains into theMississippi River. The Mississippi Riversystem Rocky Mountains andtheAppalachian inthewest Mountains intheeast enormous. For example, most oftheprecipitation that the fallsbetween streams that orrivers flow into larger ones. systems river are Some and intheatmosphere. is found inlakes, rivers, wetlands, rock thesoil, layers below thesurface, the United States andisupto 3kmthick. The rest ofEarth’s fresh water imagine. For instance, that theicesheet covers Antarctica isaslarge as is locked upinicecaps andglaciers that are largeare so they hard to shows thelocation Figure 3.8 contain relativelylittlestoredwater. Aquifers

fresh water Figure 3.7

Aquifers underliemuchoftheUnitedStates. The brownareasarerocksthat . Most ofthefresh ­ are smaller, tributaries water The DynamicEarth Chapter 3: Figure 3.7 Louisiana. a riverinthewetlandsofsouthern a networkoftributariesflowinginto River System critical thinking to people near the coast? of the main river be of concern sprayed on crops near the head graph, why would pesticides Infer Looking at Looking the at photo- This photoshows 79 printcode=a DO NOT EDIT--Changes mustbemadethrough “File info” The colorsrepresent­ The Biosphere biosphere? makeslifepossibleinthe Explain What 80 Figure 3.9 Che c Introduction toEnvironmental Science Unit 1: k f o r Understanding This illustrationofthebiosphereshowsthe concentrationplantlifeonlandandinocean. different concentrationsofplantlifeinregions. The Biosphere shown in sunlight isavailable near thesurface. Plants onlandare andintheocean only inthebiosphere. able combinations ofthethings that are organisms tofound survive need allows aplanet to maintain anatmosphere materials. andto cycle Suit The materials that organisms require must Gravity continually cycled. be requires liquidwater, moderate temperatures, andasource ofenergy. andaboutocean 9kminto theatmosphere. oftheatmosphere.part The biosphere extends about 12kminto the ofthegeosphere, part uppermost most ofthehydrosphere, andthelower Earth’s inwhich lifecan surface exist. The biosphere ismade upofthe dead plants, animals, andprotists that downfrom drift thesurface. thermal vents, most oftheorganisms that on feed livein the ocean deep algae are knownasphytoplankton that forbacteria . Except live at hydro- algae float at Thesetiny, oftheocean. thesurface free-floating, marine otherorganism from itsfood gets most every plants andalgae. Most ofthe relation to thesize oftheplanet. The illustratesparison how small thelayer that ofEarth lifeisin can support wereIf theEarth anapple, thebiosphere itsskin. wouldbe This com- The biosphere islocated near Earth’s because most surface ofthe because ofseveral onEarth exists important factors.Life Most life Figure 3.9 . Plants sunlight need to produce andal- theirfood, biosphere isthenarrow layer around -

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©Geoff Kidd/SPL/Photo Researchers, Inc. Energy FlowintheBiosphere matter reaches thisway. Earth by cometsandmeteorites. Now, however, little Matter asitwas was to theearlyhit added Earth ing environment. was system. onceanopen Earth exchanged asystem andthesurround between - space. environment asheat, which iseventually lost into chain,the food ofenergy islost to some the may eaten be by anotheranimal. At each stage in is transferred to theanimal. The animal, inturn, animal eats aplant, theenergy stored intheplant in thebiosphere to make an When theirfood. is heat. Energy from by thesun isused plants the only thing that leaves insignificant amounts significant amounts isenergy from thesun, and system because theonly thing that enters in the system, but matter not.isaclosed does Earth flow ofmatter andenergy. in suppliedconstantly.be The Eden Project, shown is continually Energy, recycled. however, must comes available to otherorganisms. This matter is broken downandthematter- be initsbody anorganismWhen inthebiosphere dies, itsbody Figure 3.10 In systemmatter, both anopen andenergy are In system, energy enters aclosed andleaves Section 3 name 4. describe 3. describe 2. name 1. ReviewingMainIdeas the biosphere. processes inthewater cycle. , is a closed system, isaclosed that this models two factors thattwo confine living things to each ofthethreeand describe major the two types of ocean currents. of ocean types the two the properties water. ofocean Formative Assessment Figure 3.10 that wereconstructedinanoldclaypitEngland. closed system. The EdenProjectishousedwithinaseriesofdomes biosphere. Inthisproject, plantsfromallovertheworldliveina Closed System analyzingRelationships 6. a 5. CriticalThinking body consideredbody system? anopen were greater than the area of the world ocean? Earth’s climate change if the land area on Earth “A Global Temperature Regulator.” How might role in regulating temperature under the heading nalyzing The EdenProjectisanattempttomodelthe The DynamicEarth Chapter 3: P rocesses

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Maps in Action Earthquake Hazard Map of the Contiguous United States

Earthquake Hazard Levels

Map Skills Use the earthquake-hazard map of the contiguous United States to answer the questions below.

1. Using a Key Which area of the contiguous United 4. Inferring Relationships Most earthquakes take States has a very high earthquake-hazard level? place near tectonic plate boundaries. Based on the hazard levels, where do you think a boundary between 2. Using a Key Determine which areas of the two tectonic plates is located in the United States? contiguous United States have very low earthquake- hazard levels. 5. Forming a Hypothesis The New Madrid earthquake zone passes through southeastern Missouri and western 3. Analyzing Relationships In which areas of the Tennessee and has experienced some of the most widely contiguous United States would scientists most likely felt earthquakes in U.S. history. Yet this earthquake zone set up earthquake-sensing devices? lies far from any tectonic plate boundary. Propose a hypothesis that would explain these earthquakes.

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Society and the Environment ECOZine Go online for the latest environmental science at HMDScience.com news and updates on all EcoZine articles.

Ocean This map shows the possible trajectory of the toys and their estimated locations on certain dates as they floated across the Currents Pacific Ocean from the point of the spill to recovery points in Alaska.

Ocean currents are important in transporting heat, water, nutrients, pollutants, and organisms around the world. Even though they are important, ocean currents have been hard to study. Scientists used to drop labeled bottles in the oceans in different places and then recorded where they were picked up.— Now, oceanographers attach transmitters to drifters. These transmitters send their position to satellites overhead, providing scientists with information that is helpful in a variety of ways, from protecting endangered species to making important decisions with far-reaching effects.

Watch Out For Debris! did not form in a way to take oil south. Instead, the oil stayed The Hawaiian monk seal is one of the most endangered relatively close to the spill. In fact, the currents kept the oil in marine mammals in the world, with a population around a place where bacteria could help to break it down, possibly 1,200 individuals. Monk seals live in the remote Northwest reducing the impact of the spill. Hawaiian Islands (NWHI), hundreds of kilometers from the nearest human populations. Unfortunately, many seals have Toys Ahoy!! still been killed when they were entangled in discarded fishing Despite more advanced methods, data that help us under­ gear that was dumped into the ocean hundreds or thousands stand ocean currents sometimes comes from the most of kilometers away. This is because the currents of the Pacific unusual sources! In 1992, a container ship traveling northwest Ocean carry the debris to the areas where the seals feed, of Hawaii ran into a storm. One of the containers that washed rest, and have their pups. Since 1996, around 500 metric overboard held 29,000 plastic toys. Over the next few years, tons of debris have been removed from the beaches of the the toys began washing up along the Alaskan coast from Sitka NWHI! This has helped keep monk seals safer, but the currents to theWhat Bering Do Sea. You Comparing Think? data from the toys with other keep bringing more debris to Hawaii, so these efforts must data, the researchers concluded that, although the current continue. across the northeast Pacific Ocean changes little from year to year, in 1990 and 1992 the current was unusually far north. Oil drilling In order to meet the energy demands of the world, it is necessary to drill oil wells in deep ocean waters. During What Do You Think? the summer of 2010, the Deepwater Horizon oil platform Oil fields off the north coast of Cuba are now being exploded and sank, releasing about five million barrels of oil opened for oil drilling. People in the Florida Keys into the Gulf of Mexico. Understanding currents was critical to and southeast Florida are concerned about this responding appropriately to the spill. The Loop Current could drilling. Use the map of currents in Figure 3.6 as a reference to explain why. How should the U.S. have taken oil from off of Louisiana to the Florida Keys and respond to this drilling? even up the East Coast of the U.S. Luckily, the loop current ©PhotoDisc/Getty Images

Chapter 3: The Dynamic Earth 83 printcode=a DO NOT EDIT--Changes mustbemadethrough “File info” Chapter 3 84 Section 3 Section 2 Section 1 Introduction toEnvironmental Science Unit 1: The The Geosphere Biosphere The Hydrosphere and Atmosphere Summary Objectives • • • • • Objectives • • • • • • Objectives • • • • •

action of water andwind. ­action ofwater Earth’s arecontinuallyalteredbythe surfacefeatures plates. theboundariesoftectonic occurat are alleventsthat Earthquakes, volcanic eruptions, and mountain building ,plates whichcollide, separate, orslippastoneanother. Earth’s surfaceisbrokenintopiecescalledtectonic composition andstructure. Earth’s interiorisdividedintolayersbasedon soils and sediments on Earth’s surface, is the geosphere. The solid part of the Earth that consists of all rock, and the leaves Earth,leaves doesnot. butmatter Earth isaclosed entersand systembecauseenergy Earth wherelifecanexist. thesurfaceof layerat The biosphereisthenarrow near.land theyflow Surface currentsintheoceanaffectclimate ofthe intheatmosphere. temperatures regulating fromsunlight,The oceanabsorbsandstoresenergy based ontemperature. the surfacezone, thethermocline, andthedeepzone— Water intheoceancanbedividedintothreezones— Earth’s surface. The hydrosphereincludesornear at allofthewater as thegreenhouseeffect. fromEarth’s ofheat escape isknown surfaceinwhat Some ofthegasesinEarth’s the slow atmosphere ­conduction, andconvection. byradiation, istransferredinthe atmosphere Heat altitudes. different takeplaceat that on changesintemperature Earth’s isdividedintofourlayersbased atmosphere nitrogen andoxygen. iscomposed almostentirelyof The atmosphere . the atmosphere surroundstheEarthiscalled The mixtureofgasesthat Key Terms erosion weathering chemical tectonic plate asthenosphere lithosphere core mantle crust hydrosphere geosphere Key Terms biosphere fresh water salinity precipitation condensation evaporation cyclewater Key Terms greenhouse convection conduction radiation ozone stratosphere troposphere atmosphere effect

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Chapter 3 Review

Reviewing Key Terms 14. The ozone layer is located in the Use each of the following terms in a separate sentence. a. stratosphere. 1. tectonic plate b. mesosphere. 2. erosion c. thermosphere. 3. radiation d. troposphere. 4. ozone 15. Convection is defined as the 5. salinity a. transfer of energy across space. For each pair of terms, explain how the meanings of b. direct transfer of energy. the terms differ. c. trapping of heat near the Earth by gases. 6. lithosphere and asthenosphere d. transfer of heat by currents. 7. conduction and convection 16. Which of the following gases is not a green­ 8. crust and mantle house gas? 9. evaporation and condensation a. water vapor 10. Concept Map Use the following terms to create b. nitrogen a concept map: geosphere, crust, mantle, core, lithosphere, asthenosphere, and tectonic plate. c. methane d. carbon dioxide

Reviewing Main Ideas 17. Liquid water turns into gaseous water vapor in a process called 11. The thin layer at Earth’s surface where life exists is called the a. precipitation. a. geosphere. b. convection. b. atmosphere. c. evaporation. c. hydrosphere. d. condensation. d. biosphere. 18. Currents at the surface of the ocean are moved mostly by 12. The thin layer of the Earth upon which tectonic plates move around is called the a. heat. a. mantle. b. wind. b. asthenosphere. c. salinity. c. lithosphere. d. the mixing of warm and cold water. d. outer core. 19. Which of the following statements about the biosphere is not true? 13. Seventy-eight percent of Earth’s atmosphere is made up of a. The biosphere is a system closed to matter. a. oxygen. b. Energy enters the biosphere in the form of sunlight. b. hydrogen. c. Nutrients in the biosphere must be c. nitrogen. continuously recycled. d. carbon dioxide. d. Matter is constantly added to the biosphere.­

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Chapter Review

Short Answer Critical Thinking 20. How do seismic waves give scientists information 27. Making Predictions The eruption of Mount about Earth’s interior? Pinatubo in 1991 reduced global temperature by 21. Explain the effect of gravity on Earth’s several tenths of a Celsius degree for several years. atmosphere. Write a paragraph predicting what might happen to Earth’s climate if several large-scale eruptions 22. Explain how convection currents transport heat in took place at the same time? the atmosphere. 28. Analyzing Processes Read about the heating 23. Why does land that is near the ocean change of Earth’s surface and the absorption of incoming temperature less rapidly than land that is located solar radiation under the heading “Warming farther inland? of the Atmosphere.” How might the Earth be 24. Why is life on Earth confined to such a narrow different if the Earth’s surface absorbed greater or layer near the Earth’s surface? lesser percentages of radiation? 29. Analyzing Processes Surface currents are de­ flected by continental landmasses. How might Interpreting Graphics the pattern of Earth’s surface currents change The map below shows the different amounts of if the Earth had no landmasses? Where on the chlorophyll in the ocean. Chlorophyll is the pigment world ocean might the majority of warm surface that makes plants and algae green. Chlorophyll currents be located? Where would the cold identifies the presence of marine algae. The red and surface currents be located? orange colors on the map show the highest amounts 30. History Scientists believe that some human of chlorophyll, the blue and purple colors on the map migration between distant landmasses may have show the smallest amounts of chlorophyll. Use the map taken place on rafts powered only by the wind to answer questions 25–26. and ocean currents. Look at Figure 3.6, which 25. Infer Is there a greater concentration of marine shows the Earth’s surface currents. Hypo­thesize algae at location A or at location B? potential migratory routes these early seafarers may have followed. 26. Conclude What conclusion can you reach about 31. Plotting Seismic Activity conditions in the parts of the ocean where marine Most earthquakes algae may prefer to live? take place near tectonic plate boundaries. Using the encyclopedia, the Internet, or another source, find at least 20 locations where major earthquakes took place during the 20th century. Plot these locations on a map of the world that shows Earth’s tectonic plates. Did the majority of earthquakes occur at or near tectonic plate boundaries?

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Chapter Review

Analyzing Data STUDYSKILL CASESTUDY Use the graph below to answer questions 32–33. 37. According to the passage, what purpose 32. Analyzing Data Rearrange the oceans in order do coastal wetlands perform to reduce the of highest depth-to-area ratio to lowest depth-to- damage from a storm surge? area ratio. 38. According to the passage, what two factors 33. Making Calculations On the graph, you are increased the effectiveness of wetlands in given the average depths of the four oceans. From Why It Matters reducing damage from tsunamis? these data, calculate the average depth of the world ocean. Why It Matters 39. Explain how using 180 4,500 satellites to monitor 160 Area 4,000 weather conditions 140 Depth 3,500 benefits people 120 3,000 globally. 100 2,500 80 2,000

Area of oceans 60 1,500 (in millions of km2) 40 1,000 Depth of oceans (m) 20 500 0 0 Pacific Atlantic Indian Arctic Ocean Ocean Ocean Ocean STUDYSKILL The Importance of Nouns Most multiple-choice Making Connections questions center around the definitions of nouns. When you study, pay attention to the definitions of nouns that appear to 34. Communicating Main Ideas Describe the be important in the text. These nouns will often be boldfaced three important ways in which the movement of key terms or italicized secondary terms. energy takes place in Earth’s atmosphere. 35. Writing Persuasively Write a persuasive essay that explains why the Earth today should be regarded as a closed system for matter rather than an open system. 36. Outlining Topics Write a one-page outline that describes some of the important inter­actions that take place in the Earth system. ©Earth Imaging/Stone/Getty Images

Chapter 3: The Dynamic Earth 87 ExplorationLab Simulation Beaches Objectives Almost one-fourth of all the structures that have been built within Examine models that show 150 m of the U.S. coastline, including the Great Lakes, will be lost to beach how the forces generated by wave action build, shape, and erosion over the next 60 years, according to a June 2000 report released by erode beaches. the Federal Emergency Management Agency (FEMA). The supply of sand for most beaches has been cut off by dams built on rivers and streams Hypothesize ways in which that would otherwise carry sand to the sea. Waves generated by storms beaches can be preserved from the erosive forces of also erode beaches. Longshore currents, which are generated by waves wave activity. that break at an angle to a shoreline, transport sediment continuously and change the shape of a shoreline. Materials You will now use a series of models to help you understand how metric ruler beaches can be both washed away and protected from the effects of waves milk cartons, empty, small (2) and longshore currents. pebbles plaster of Paris Procedure plastic container (large) 1. At least one day before you begin the investigation, make two plaster or long wooden box lined blocks. Mix a small amount of water with plaster of Paris until the with plastic mixture is smooth. Add five or six small rocks to the mixture for rocks, small added weight. Pour the plaster mixture into the milk cartons. sand, 5 to 10 lb Let the plaster harden overnight. Carefully peel the milk cartons wooden block, large away from the plaster.

2. Prepare a wooden box lined with plastic or another similar large, shallow container. Make a model of a beach by placing a mixture of sand and small pebbles at one end of the container. The beach should occupy about one-fourth the length of the container. See step 2. In the area in front of the sand, add water to a depth of 2 to 3 cm. Use the large wooden block to generate several waves by moving the block up and down in the water at the end of the container opposite the beach. Continue this wave action until about half the beach has moved. Record your observations.

3. Remove the water, and rebuild the beach. In some places, breakwaters have been built offshore in an attempt to protect beaches from washing away. Build a breakwater by placing two plaster blocks across the middle of the container. Using the metric ruler, leave a 4 cm space between the blocks. See step 3. Use a wooden block to generate waves. Describe the results.

4. Drain the water, and make a new beach along one side of the container for about half its length. See step 4. Using the wooden block, generate a series of waves from the same end of the container as the end of the beach. Record your observations. Step 2 Use a wooden block to generate waves at the end of the container opposite the beach.

88 Unit 1: Introduction to Environmental Science 5. Rebuild the beach along the same side of the container. Jetties or breakwaters are structures that can be built out into the ocean to intercept and break up a longshore current. Make a jetty by placing one of the small plaster blocks in the sand. See step 5. As you did in the previous steps, use the wooden block to generate waves. De- scribe the results.

6. Remove the wet sand, and put it in a container. Dispose of the water. (Note: Follow your teacher’s instructions for disposal of the sand and water. Never pour water containing sand into a sink.) Step 3 Build a breakwater by placing two plastic blocks across the middle of the container. Analysis 1. Describing Events In step 2 of the procedure, what happened to the beach when water was first poured into the container? What happened to the particles of fine sand? Predict what would happen to the beach if it had no source of additional sand.

2. Analyzing Results In step 3 of the procedure, did the breakwater help protect the beach from washing away?

3. Describing Events What happened to the beach that you made in step 4 of the procedure? What happened to the shape of the waves along the beach?

4. Analyzing Results What effect did the jetty have on the beach that Step 4 Make a beach lengthwise along one side of you made in step 5 of the procedure? the container. The length of the beach should equal one-half the length of the container.

Conclusions 5. Drawing Conclusions What can be done to preserve a beach area from being washed away as a result of wave action and long- shore currents?

6. Drawing Conclusions What can be done to preserve a beach area that has been changed as a result of excessive use by people?

Extension 7. Building Models Make a beach that would be in danger of be- ing washed away by a longshore current. Based on what you have learned, build a model in which the beach would be preserved by Step 5 Place one of the small plaster blocks in the a breakwater or jetties. Explain how your model illustrates ways in sand to make a jetty. which longshore currents can be intercepted and broken up.

Chapter 3: The Dynamic Earth 89