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L_0030 | world climates | T_0306 | Dry climates receive very little rainfall. They also have high rates of evaporation. This makes them even drier. The driest climates are deserts. Most occur between about 15 and 30 latitude. This is where dry air sinks to the surface in the global circulation cells. Deserts receive less than 25 centimeters (10 inches) of rain per year. They may be covered with sand dunes or be home to sparse but hardy plants (see Figure 17.11). With few clouds, deserts have hot days and cool nights. Other dry climates get a little more precipitation. They are called steppes. These regions have short grasses and low bushes (see Figure 17.11). Steppes occur at higher latitudes than deserts. They are dry because they are in continental interiors or rain shadows. | text | null |
L_0030 | world climates | T_0307 | Temperate climates have moderate temperatures. These climates vary in how much rain they get and when the rain falls. You can see different types of temperate climates in Figure 17.12. Mediterranean climates are found on the western coasts of continents. The latitudes are between 30 and 45. The coast of California has a Mediterranean climate. Temperatures are mild and rainfall is moderate. Most of the rain falls in the winter, and summers are dry. To make it through the dry summers, short woody plants are common. Marine west coast climates are also found on the western coasts of continents. They occur between 45 and 60 latitude. The coast of Washington State has this type of climate. Temperatures are mild and theres plenty of rainfall all year round. Dense fir forests grow in this climate. Humid subtropical climates are found on the eastern sides of continents between about 20 and 40 latitude. The southeastern U.S. has this type of climate. Summers are hot and humid, but winters are chilly. There is moderate rainfall throughout the year. Pine and oak forests grow in this climate. | text | null |
L_0030 | world climates | T_0308 | Continental climates are found in inland areas. They are too far from oceans to experience the effects of ocean water. Continental climates are common between 40 and 70 north latitude. There are no continental climates in the Southern Hemisphere. Can you guess why? The southern continents at this latitude are too narrow. All of their inland areas are close enough to a coast to be affected by the ocean! Humid continental climates are found between 40 and 60 north latitude. The northeastern U.S. has this type of climate. Summers are warm to hot, and winters are cold. Precipitation is moderate, and it falls year round. Deciduous trees grow in this climate. They lose their leaves in the fall and grow new ones in the spring. Subarctic climates are found between 60 and 70 north latitude. Much of Canada and Alaska have this type of climate. Summers are cool and short. Winters are very cold and long. Little precipitation falls, and most of it falls during the summer. Conifer forests grow in this climate (see Figure 17.13). | text | null |
L_0030 | world climates | T_0309 | Polar climates are found near the North and South Poles. They also occur on high mountains at lower latitudes. The summers are very cool, and the winters are frigid. Precipitation is very low because its so cold. You can see examples of polar climates in Figure 17.14. Polar tundra climates occur near the poles. Tundra climates have permafrost. Permafrost is layer of ground below the surface that is always frozen, even in the summer. Only small plants, such as mosses, can grow in this climate. Alpine tundra climates occur at high altitudes at any latitude. They are also called highland climates. These regions are very cold because they are so far above sea level. The alpine tundra climate is very similar to the polar tundra climate. Ice caps are areas covered with thick ice year round. Ice caps are found only in Greenland and Antarctica. Temperatures and precipitation are both very low. What little snow falls usually stays on the ground. It doesnt melt because its too cold. | text | null |
L_0030 | world climates | T_0310 | A place might have a different climate than the major climate type around it. This is called a microclimate. Look at Figure 17.15. The south-facing side of the hill gets more direct sunlight than the north side of a hill. This gives the south side a warmer microclimate. A microclimate can be due to a place being deeper. Since cold air sinks, a depression in the land can be a lot colder than the land around it. | text | null |
L_0031 | climate change | T_0311 | Earths climate has changed many times through Earths history. Its been both hotter and colder than it is today. | text | null |
L_0031 | climate change | T_0312 | Over much of Earths past, the climate was warmer than it is today. Picture in your mind dinosaurs roaming the land. Theyre probably doing it in a pretty warm climate! But ice ages also occurred many times in the past. An ice age is a period when temperatures are cooler than normal. This causes glaciers to spread to lower latitudes. Scientists think that ice ages occurred at least six times over the last billion years alone. How do scientists learn about Earths past climates? | text | null |
L_0031 | climate change | T_0313 | The last major ice age took place in the Pleistocene. This epoch lasted from 2 million to 14,000 years ago. Earths temperature was only 5 C (9 F) cooler than it is today. But glaciers covered much of the Northern Hemisphere. In Figure 17.17, you can see how far south they went. Clearly, a small change in temperature can have a big impact on the planet. Humans lived during this ice age. | text | null |
L_0031 | climate change | T_0314 | Since the Pleistocene, Earths temperature has risen. Figure 17.18 shows how it changed over just the last 1500 years. There were minor ups and downs. But each time, the anomaly (the difference from average temperature) was less than 1 C (1.8 F). Since the mid 1800s, Earth has warmed up quickly. Look at Figure 17.19. The 14 hottest years on record have all occurred since 1900. Eight of them have occurred since 1998! This is what is usually meant by global warming. | text | null |
L_0031 | climate change | T_0314 | Since the Pleistocene, Earths temperature has risen. Figure 17.18 shows how it changed over just the last 1500 years. There were minor ups and downs. But each time, the anomaly (the difference from average temperature) was less than 1 C (1.8 F). Since the mid 1800s, Earth has warmed up quickly. Look at Figure 17.19. The 14 hottest years on record have all occurred since 1900. Eight of them have occurred since 1998! This is what is usually meant by global warming. | text | null |
L_0031 | climate change | T_0315 | Natural processes caused earlier climate changes. Human beings are the main cause of recent global warming. | text | null |
L_0031 | climate change | T_0316 | Several natural processes may affect Earths temperature. They range from sunspots to Earths wobble. Sunspots are storms on the Sun. When the number of sunspots is high, the Sun gives off more energy than usual. Still, there is little evidence for climate changing along with the sunspot cycle. Plate movements cause continents to drift closer to the poles or the equator. Ocean currents also shift when continents drift. All these changes can affect Earths temperature. Plate movements trigger volcanoes. A huge eruption could spew so much gas and ash into the air that little sunlight would reach the surface for months or years. This could lower Earths temperature. A large asteroid hitting Earth would throw a lot of dust into the air. This could block sunlight and cool the planet. Earth goes through regular changes in its position relative to the Sun. Its orbit changes slightly. Earth also wobbles on its axis of rotation. The planet also changes the tilt on its axis. These changes can affect Earths temperature. | text | null |
L_0031 | climate change | T_0317 | Recent global warming is due mainly to human actions. Burning fossil fuels adds carbon dioxide to the atmosphere. Carbon dioxide is a greenhouse gas. Its one of several that human activities add to the atmosphere. An increase in greenhouse gases leads to greater greenhouse effect. The result is increased global warming. Figure 17.20 shows the increase in carbon dioxide since 1960. | text | null |
L_0031 | climate change | T_0318 | As Earth has gotten warmer, sea ice has melted. This has raised the level of water in the oceans. Figure 17.21 shows how much sea level has risen since 1880. | text | null |
L_0031 | climate change | T_0319 | Earths temperature will keep rising unless greenhouse gases are curbed. The temperature in 2100 may be as much as 5 C (9 F) higher than it was in 2000. Since the glacial periods of the Pleistocene, average temperature has risen about 4 C. Thats just 4 C from abundant ice to the moderate climate we have today. How might a 5 C increase in temperature affect Earth in the future? Warming will affect the entire globe by the end of this century. The map in Figure 17.22 shows the average temperature in the 2050s. This is compared with the average temperature in 1971 to 2000. In what place is the temperature increase the greatest? Where in the United States is the temperature increase the highest? As temperature rises, more sea ice will melt. Figure 17.23 shows how much less sea ice there may be in 2050 if temperatures keep going up. This would cause sea level to rise even higher. Some coastal cities could be under water. Millions of people would have to move inland. How might other living things be affected? | text | null |
L_0031 | climate change | T_0320 | Youve probably heard of El Nio and La Nia. These terms refer to certain short-term changes in climate. The changes are natural and occur in cycles. To understand the changes, you first need to know what happens in normal years. This is shown in Figure 17.24. | text | null |
L_0031 | climate change | T_0321 | During an El Nio, the western Pacific Ocean is warmer than usual. This causes the trade winds to change direction. The winds blow from west to east instead of east to west. This is shown in Figure 17.25. The warm water travels east across the equator, too. Warm water piles up along the western coast of South America. This prevents upwelling. Why do you think this is true? These changes in water temperature, winds, and currents affect climates worldwide. The changes usually last a year or two. Some places get more rain than normal. Other places get less. In many locations, the weather is more severe. | text | null |
L_0031 | climate change | T_0321 | During an El Nio, the western Pacific Ocean is warmer than usual. This causes the trade winds to change direction. The winds blow from west to east instead of east to west. This is shown in Figure 17.25. The warm water travels east across the equator, too. Warm water piles up along the western coast of South America. This prevents upwelling. Why do you think this is true? These changes in water temperature, winds, and currents affect climates worldwide. The changes usually last a year or two. Some places get more rain than normal. Other places get less. In many locations, the weather is more severe. | text | null |
L_0031 | climate change | T_0322 | La Nia generally follows El Nio. It occurs when the Pacific Ocean is cooler than normal. Figure 17.26 shows what happens. The trade winds are like they are in a normal year. They blow from east to west. But in a La Nia the winds are stronger than usual. More cool water builds up in the western Pacific. These changes can also affect climates worldwide. | text | null |
L_0031 | climate change | T_0322 | La Nia generally follows El Nio. It occurs when the Pacific Ocean is cooler than normal. Figure 17.26 shows what happens. The trade winds are like they are in a normal year. They blow from east to west. But in a La Nia the winds are stronger than usual. More cool water builds up in the western Pacific. These changes can also affect climates worldwide. | text | null |
L_0031 | climate change | T_0323 | Some scientists think that global warming is affecting the cycle of El Nio and La Nia. These short-term changes seem to be cycling faster now than in the past. They are also more extreme. | text | null |
L_0033 | cycles of matter | T_0337 | Carbon is an element. By itself, its a black solid. You can see a lump of carbon in Figure 18.10. Carbon is incredibly important because of what it makes when it combines with many other elements. Carbon can form a wide variety of substances. For example, in the air, carbon combines with oxygen to form the gas carbon dioxide. In living things, carbon combines with several other elements. For example, it may combine with nitrogen and | text | null |
L_0033 | cycles of matter | T_0338 | In the carbon cycle, carbon moves through living and nonliving things. Carbon actually moves through two cycles that overlap. One cycle is mainly biotic; the other cycle is mainly abiotic. Both cycles are shown in Figure 18.11. | text | null |
L_0033 | cycles of matter | T_0339 | Producers such as plants or algae use carbon dioxide in the air to make food. The organisms combine carbon dioxide with water to make sugar. They store the sugar as starch. Both sugar and starch are carbohydrates. Consumers get carbon when they eat producers or other consumers. Carbon doesnt stop there. Living things get energy from food in a process called respiration. This releases carbon dioxide back into the atmosphere. The cycle then repeats. | text | null |
L_0033 | cycles of matter | T_0340 | Carbon from decaying organisms enters the ground. Some carbon is stored in the soil. Some carbon may be stored underground for millions of years. This will form fossil fuels. When volcanoes erupt, carbon from the mantle is released as carbon dioxide into the air. Producers take in the carbon dioxide to make food. Then the cycle repeats. The oceans also play an important role in the carbon cycle. Ocean water absorbs carbon dioxide from the air. In fact, the oceans contain 50 times more carbon than the atmosphere. Much of the carbon sinks to the bottom of the oceans, where it may stay for hundreds of years. | text | null |
L_0033 | cycles of matter | T_0341 | Human actions are influencing the carbon cycle. Burning of fossil fuels releases the carbon dioxide that was stored in ancient plants. Carbon dioxide is a greenhouse gas and is a cause of global warming. Forests are also being destroyed. Trees may be cut down for their wood, or they may be burned to clear the land for farming. Burning wood releases more carbon dioxide into the atmosphere. You can see how a tropical rainforest was cleared for farming in Figure 18.12. With forests shrinking, there are fewer trees to remove carbon dioxide from the air. This makes the greenhouse effect even worse. | text | null |
L_0033 | cycles of matter | T_0342 | Living things also need nitrogen. Nitrogen is a key element in proteins. Like carbon, nitrogen cycles through ecosystems. You can see the nitrogen cycle in Figure 18.13. | text | null |
L_0033 | cycles of matter | T_0343 | Air is about 78 percent nitrogen. Decomposers release nitrogen into the air from dead organisms and their wastes. However, producers such as plants cant use these forms of nitrogen. Nitrogen must combine with other elements before producers can use it. This is done by certain bacteria in the soil. Its called fixing nitrogen. | text | null |
L_0033 | cycles of matter | T_0344 | Nitrogen is one of the most important nutrients needed by plants. Thats why most plant fertilizers contain nitrogen. Adding fertilizer to soil allows more plants to grow. As a result, a given amount of land can produce more food. So far, so good. But what happens next? Rain dissolves fertilizer in the soil. Runoff carries it away. The fertilizer ends up in bodies of water, from ponds to oceans. The nitrogen is a fertilizer in the water bodies. Since there is a lot of nitrogen it causes algae to grow out of control. Figure 18.14 shows a pond covered with algae. Algae may use up so much oxygen in the water that nothing else can grow. Soon, even the algae die out. Decomposers break down the dead tissue and use up all the oxygen in the water. This creates a dead zone. A dead zone is an area in a body of water where nothing grows because there is too little oxygen. There is a large dead zone in the Gulf of Mexico. You can see it Figure 18.14. | text | null |
L_0034 | the human population | T_0345 | A population usually grows when it has what it needs. If theres plenty of food and other resources, the population will get bigger. Look at Table 18.1. It shows how a population of bacteria grew. A single bacteria cell was added to a container of nutrients. Conditions were ideal. The bacteria divided every 30 minutes. After just 10 hours, there were more than a million bacteria! Assume the bacteria population keeps growing at this rate. How many bacteria will there be at 10.5 hours? Or at 12 hours? Time (hours) 0 0.5 Number of Bacteria 1 2 Time (hours) 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10 Number of Bacteria 4 8 16 32 64 128 256 512 1,024 2,048 4,096 8,192 16,384 32,768 65,536 131,072 262,144 524,288 1,048,576 | text | null |
L_0034 | the human population | T_0346 | The population growth rate is how fast a population is growing. The letter r stands for the growth rate. The growth rate equals the number of new members added to the population in a year for each 100 members already in the population. The growth rate includes new members added to the population and old members removed from the population. Births add new members to the population. Deaths remove members from the population. The formula for population growth rate is: r = b - d, where b = birth rate (number of births in 1 year per 100 population members) d = death rate (number of deaths in 1 year per 100 population members) If the birth rate is greater than the death rate, r is positive. This means that the population is growing bigger. For example, if b = 10 and d = 8, r = 2. This means that the population is growing by 2 individuals per year for every 100 members of the population. This may not sound like much, but its a fairly high rate of growth. A population growing at this rate would double in size in just 35 years! If the birth rate is less than the death rate, r is negative. This means that the population is becoming smaller. What do you think might cause this to happen? | text | null |
L_0034 | the human population | T_0347 | A population cant keep growing bigger and bigger forever. Sooner or later, it will run out of things it needs. For a given species, there is a maximum population that can be supported by the environment. This maximum is called the carrying capacity. When a population gets close to the carrying capacity, it usually grows more slowly. You can see this in Figure 18.16. When the population reaches the carrying capacity, it stops growing. | text | null |
L_0034 | the human population | T_0348 | Figure 18.17 shows how the human population has grown. It grew very slowly for tens of thousands of years. Then, in the 1800s, something happened to change all that. The human population started to grow much faster. | text | null |
L_0034 | the human population | T_0349 | The industrial revolution is what happened. The industrial revolution began in the late 1700s in Europe, North America, and a few other places. In these places, the human population grew faster. While there had always been a lot of births, the population grew because the death rate fell. It fell for several reasons: 1. New farm machines were invented. They increased the amount of food that could be produced. With more food, people were healthier and could live longer. 2. Steam engines and railroads were built. These machines could quickly carry food long distances. This made food shortages less likely. 3. Sanitation was improved. Sewers were dug to carry away human wastes (see Figure 18.18). This helped reduce the spread of disease. With better food and less chance of disease, the death rate fell. More children lived long enough to reach adulthood and have children of their own. As the death rate fell, the birth rate stayed high for a while. This caused rapid population growth. However, the birth rate in these countries has since fallen to a rate close to that of the low death rate. The result was slow population growth once again. These changes are called the demographic transition. | text | null |
L_0034 | the human population | T_0350 | More recently, the death rate has fallen because of the availability of more food and medical advances: A green revolution began in the mid 1900s. New methods and products increased how much food could be grown. For example, chemicals were developed that killed weeds without harming crops. Pesticides were developed that killed pests that destroyed crops. Vaccinations were developed that could prevent many diseases (see Figure 18.19). Antibiotics were discov- ered that could cure most infections caused by bacteria. Together, these two advances saved countless lives. Today in many countries, death rates have gone down but birth rates remain high. This means that the population is growing. Figure 18.20 shows the growth rates of human populations all over the world. | text | null |
L_0034 | the human population | T_0350 | More recently, the death rate has fallen because of the availability of more food and medical advances: A green revolution began in the mid 1900s. New methods and products increased how much food could be grown. For example, chemicals were developed that killed weeds without harming crops. Pesticides were developed that killed pests that destroyed crops. Vaccinations were developed that could prevent many diseases (see Figure 18.19). Antibiotics were discov- ered that could cure most infections caused by bacteria. Together, these two advances saved countless lives. Today in many countries, death rates have gone down but birth rates remain high. This means that the population is growing. Figure 18.20 shows the growth rates of human populations all over the world. | text | null |
L_0034 | the human population | T_0351 | The growth of the human population has started to slow down. You can see this in Figure 18.21. It may stop growing by the mid 2000s. Scientists think that the human population will peak at about 9 billion people. What will need to change for the population to stop growing then? | text | null |
L_0034 | the human population | T_0352 | Are 9 billion people the human carrying capacity? It looks that way in Figure 18.21. But some people think there are too many of us already. Thats because we are harming the environment. Supplying all those people with energy creates a lot of pollution. For example, huge oil spills have killed millions of living things. Burning fossil fuels pollutes the air. This also increases causes global warming. Fossil fuels and other resources are being used up. We may run out of oil by the mid 2000s. Many other resources will run out sooner or later. People are killing too many animals for food. For example, some of the best fishing grounds in the oceans have almost no fish left. People have destroyed many habitats. For example, theyve drained millions of acres of wetlands. Wetlands have a great diversity of species. As wetlands shrink, species go extinct. People have allowed alien or invasive species - species originally from a different area - to invade new habitats. Often, the aliens have no natural enemies in their new home. They may drive native species extinct. Figure People themselves are also affected by the large size of the human population. A minority of people use most of the worlds energy and other resources. Many other people lack resources. Many dont have enough to eat or live with | text | null |
L_0034 | the human population | T_0352 | Are 9 billion people the human carrying capacity? It looks that way in Figure 18.21. But some people think there are too many of us already. Thats because we are harming the environment. Supplying all those people with energy creates a lot of pollution. For example, huge oil spills have killed millions of living things. Burning fossil fuels pollutes the air. This also increases causes global warming. Fossil fuels and other resources are being used up. We may run out of oil by the mid 2000s. Many other resources will run out sooner or later. People are killing too many animals for food. For example, some of the best fishing grounds in the oceans have almost no fish left. People have destroyed many habitats. For example, theyve drained millions of acres of wetlands. Wetlands have a great diversity of species. As wetlands shrink, species go extinct. People have allowed alien or invasive species - species originally from a different area - to invade new habitats. Often, the aliens have no natural enemies in their new home. They may drive native species extinct. Figure People themselves are also affected by the large size of the human population. A minority of people use most of the worlds energy and other resources. Many other people lack resources. Many dont have enough to eat or live with | text | null |
L_0034 | the human population | T_0353 | Is it possible for all the worlds people to live well and still protect the planet? Thats the aim of sustainable development. Its goals are to: 1. Distribute resources fairly. 2. Conserve resources so they wont run out. 3. Use resources in ways that wont harm ecosystems. A smaller human population may be part of the solution. Better use of resources is another part. For example, when forests are logged, new trees should be planted. Everyone can help in the effort. What will you do? | text | null |
L_0036 | pollution of the land | T_0362 | Love Canal gained worldwide attention in the late 1970s when the press started covering its story. The story is outlined below and illustrated in Figure 19.9. | text | null |
L_0036 | pollution of the land | T_0363 | The Love Canal disaster actually began back in the mid 1900s. The disaster continues even today. Starting in the early 1940s, a big chemical company put thousands of barrels of chemical waste into an old canal. Over the next 10 years, the company dumped almost 22,000 tons of chemicals into the ground! In the early 1950s, the company covered over the barrels in the canal with soil. Then they sold the land to the city for just a dollar. The city needed the land in order to build an elementary school. The company warned the city that toxic waste was buried there. But they thought the waste was safe. The school and hundreds of homes were also built over the old canal. As it turned out, the cheap price was no bargain. Chemicals started leaking from the barrels. Chemicals seeped into basements. Chemicals bubbled up to the surface of the ground. In some places, plants wouldnt even grow on the soil. People noticed bad smells. Many got sick, especially the children. Residents wanted to know if the old chemicals were the cause. But they had a hard time getting officials to listen. So they demonstrated and demanded answers. Finally, the soil was tested and was found to be contaminated with harmful chemicals. For example, it contained a lot of lead and mercury. Both can cause permanent damage to the human nervous system. The school was closed. More than 200 homes were evacuated. Much of the Love Canal neighborhood was bulldozed away. The area had a massive clean-up effort. The cleanup cost millions of dollars. More than three decades later, much of Love Canal is still too contaminated to be safe for people. | text | null |
L_0036 | pollution of the land | T_0364 | Love Canal opened peoples eyes to toxic waste burial. They realized there must be other Love Canals all over the country. Thousands of contaminated sites were found. The Superfund Act was passed in 1980. The law required that money be set aside for cleanup of toxic waste sites, like the Elizabeth Copper Mine in Vermont (see the far-right image in Figure 19.9). The law also required safer disposal of hazardous waste in the future. | text | null |
L_0036 | pollution of the land | T_0365 | Love Canal highlighted the problem of pollution by hazardous waste. Hazardous waste is any waste that is dangerous to the health of people or the environment. It may be dangerous because it is toxic, corrosive, flammable, or explosive. Toxic waste is poisonous. Toxic waste may cause cancer or birth defects in people. It may also harm other living things. Corrosive waste is highly reactive with other substances. Corrosive waste may cause burns or destroy other materials that it touches. Flammable waste can burn easily. It may also give off harmful fumes when it burns. Explosive waste is likely to explode. The risk of explosion may be greater if the waste is mixed with other substances. Table 19.1 shows some examples of hazardous waste. Look closely. Are any of these examples lurking around your home? Example Description Cars contain toxic fluids such as brake fluid. The fluids may also be corrosive and flammable. This photo shows one way the fluids can end up in the ground. Cars use gas and oil. These materials are toxic and flammable. They pollute the land when they leak or spill. Batteries contain toxic and corrosive materials. People often toss them in the trash, but they should be disposed of properly. Electronics, such as old computers, contain toxic chem- icals. They may be sent to landfills where the toxic materials end up in the ground. Medical waste can contain many hazards: Human body fluids may cause disease; old thermometers may contain toxic mercury; and pharmaceuticals may be toxic to people and other living things. Example Description Paints can be both toxic and flammable. Paints may spill on the ground or be thrown improperly in the trash. Chemicals are applied to farm fields and lawns. They include fertilizers, herbicides, and pesticides. Many of these chemicals are toxic to people and other animals. | text | null |
L_0036 | pollution of the land | T_0366 | The greatest source of hazardous waste is industry. Agriculture is another major source. Even households produce a lot of hazardous waste. | text | null |
L_0036 | pollution of the land | T_0367 | Thanks to the lessons of Love Canal, the U.S. now has laws requiring the safe disposal of hazardous waste. Companies must ensure that hazardous waste is not allowed to enter the environment in dangerous amounts. They must also protect their workers from hazardous materials. For example, they must provide employees with the proper safety gear and training (see Figure 19.10). | text | null |
L_0036 | pollution of the land | T_0368 | Cleaning products, lawn chemicals, paints, batteries, motor oil these are just some of the many hazardous materials that may be found in households. You might think that a household doesnt produce enough hazardous waste to worry about. But when you add up all the waste from all the households in a community, its a different story. A city of just 50,000 people might produce more than 40 tons of hazardous waste each year! Clearly, how households deal with hazardous waste matters. What can your family do? Reduce, reuse, recycle, or properly dispose of the wastes. 1. Reduce the amount of hazardous products you buy. For example, if you only need a quart of paint for a job, dont buy a gallon. 2. Use less hazardous products if you can. For example, clean windows with vinegar and water instead of toxic window cleaners. 3. Reuse products if its safe to do so. For example, paint thinner that has been used to clean paint brushes can be strained and reused. 4. Recycle whenever possible. For example, some service stations allow you to drop off used motor oil, car batteries, or tires for recycling. 5. Always properly dispose of hazardous waste. For example, let liquid waste evaporate before placing the container in the trash. Proper disposal depends on the waste. Many hazardous products have disposal guidelines on the label. Thats one reason why you should keep the products in their original containers. The labels also explain how to use the products safely. Follow the instructions to protect yourself and the environment. Most communities have centers for disposing of household hazardous waste (see Figure 19.11). Do you know how to dispose of hazardous waste in your community? | text | null |
L_0036 | pollution of the land | T_0368 | Cleaning products, lawn chemicals, paints, batteries, motor oil these are just some of the many hazardous materials that may be found in households. You might think that a household doesnt produce enough hazardous waste to worry about. But when you add up all the waste from all the households in a community, its a different story. A city of just 50,000 people might produce more than 40 tons of hazardous waste each year! Clearly, how households deal with hazardous waste matters. What can your family do? Reduce, reuse, recycle, or properly dispose of the wastes. 1. Reduce the amount of hazardous products you buy. For example, if you only need a quart of paint for a job, dont buy a gallon. 2. Use less hazardous products if you can. For example, clean windows with vinegar and water instead of toxic window cleaners. 3. Reuse products if its safe to do so. For example, paint thinner that has been used to clean paint brushes can be strained and reused. 4. Recycle whenever possible. For example, some service stations allow you to drop off used motor oil, car batteries, or tires for recycling. 5. Always properly dispose of hazardous waste. For example, let liquid waste evaporate before placing the container in the trash. Proper disposal depends on the waste. Many hazardous products have disposal guidelines on the label. Thats one reason why you should keep the products in their original containers. The labels also explain how to use the products safely. Follow the instructions to protect yourself and the environment. Most communities have centers for disposing of household hazardous waste (see Figure 19.11). Do you know how to dispose of hazardous waste in your community? | text | null |
L_0037 | introduction to earths surface | T_0369 | To describe your location wherever you are on Earths surface, you could use a coordinate system. For example, you could say that you are at 1234 Main Street, Springfield, Ohio. Or you could use a point of reference. If you want to meet up with a friend, you could tell him the distance and direction you are from the reference point. An example is, I am at the corner of Maple Street and Main Street, about two blocks north of your apartment. When studying Earths surface, scientists must be able to pinpoint a feature they are interested in. Scientists and others have a system to describe the location of any feature. Usually they use latitude and longitude as a coordinate system. Lines of latitude and longitude form a grid. The grid is centered on a reference point. You will learn about this type of grid when we discuss maps later in this chapter. | text | null |
L_0037 | introduction to earths surface | T_0370 | When an object is moving, it is not enough to describe its location. We also need to know direction. Direction is important for describing moving objects. For example, a wind blows a storm over your school. Where is that storm coming from? Where is it going? The most common way to describe direction is by using a compass. A compass is a device with a floating needle (Figure 2.1). The needle is a small magnet that aligns itself with the Earths magnetic field. The compass needle always points to magnetic north. If you have a compass and you find north, you can then know any other direction. See the directions, such as east, south, west, etc., on a compass rose. A compass needle lines up with Earths magnetic north pole. This is different from Earths geographic north pole, or true north. The geographic north pole is the top of the imaginary axis around which Earth rotates. The geographic north pole is much like the spindle of a spinning top. The location of the geographic north pole does not change. However, the magnetic north pole shifts in location over time. Depending on where you live, you can correct for the difference between the two poles when you use a map and a compass (Figure 2.2). Some maps have a double compass rose. This allows users to make the corrections between magnetic north and true north. An example is a nautical chart that boaters use to chart their positions at sea (Figure 2.3). | text | null |
L_0037 | introduction to earths surface | T_0371 | As you know, the surface of Earth is not flat. Some places are high and some places are low. For example, mountain ranges like the Sierra Nevada in California or the Andes in South America are high above the surrounding areas. We can describe the topography of a region by measuring the height or depth of that feature relative to sea level (Figure mountains, while others are more like small hills! Relief, or terrain, includes all the landforms of a region. A topographic map shows the height, or elevation, of features in an area. This includes mountains, craters, valleys, and rivers. For example, Figure 2.5 shows the San Francisco Peaks in northern Arizona. Features on the map include mountains, hills and lava flows. You can recognize these features from the differences in elevation. We will talk about some different landforms in the next section. | text | null |
L_0037 | introduction to earths surface | T_0371 | As you know, the surface of Earth is not flat. Some places are high and some places are low. For example, mountain ranges like the Sierra Nevada in California or the Andes in South America are high above the surrounding areas. We can describe the topography of a region by measuring the height or depth of that feature relative to sea level (Figure mountains, while others are more like small hills! Relief, or terrain, includes all the landforms of a region. A topographic map shows the height, or elevation, of features in an area. This includes mountains, craters, valleys, and rivers. For example, Figure 2.5 shows the San Francisco Peaks in northern Arizona. Features on the map include mountains, hills and lava flows. You can recognize these features from the differences in elevation. We will talk about some different landforms in the next section. | text | null |
L_0037 | introduction to earths surface | T_0371 | As you know, the surface of Earth is not flat. Some places are high and some places are low. For example, mountain ranges like the Sierra Nevada in California or the Andes in South America are high above the surrounding areas. We can describe the topography of a region by measuring the height or depth of that feature relative to sea level (Figure mountains, while others are more like small hills! Relief, or terrain, includes all the landforms of a region. A topographic map shows the height, or elevation, of features in an area. This includes mountains, craters, valleys, and rivers. For example, Figure 2.5 shows the San Francisco Peaks in northern Arizona. Features on the map include mountains, hills and lava flows. You can recognize these features from the differences in elevation. We will talk about some different landforms in the next section. | text | null |
L_0037 | introduction to earths surface | T_0371 | As you know, the surface of Earth is not flat. Some places are high and some places are low. For example, mountain ranges like the Sierra Nevada in California or the Andes in South America are high above the surrounding areas. We can describe the topography of a region by measuring the height or depth of that feature relative to sea level (Figure mountains, while others are more like small hills! Relief, or terrain, includes all the landforms of a region. A topographic map shows the height, or elevation, of features in an area. This includes mountains, craters, valleys, and rivers. For example, Figure 2.5 shows the San Francisco Peaks in northern Arizona. Features on the map include mountains, hills and lava flows. You can recognize these features from the differences in elevation. We will talk about some different landforms in the next section. | text | null |
L_0037 | introduction to earths surface | T_0372 | If you take away the water in the oceans (Figure 2.6), Earth looks really different. You see that the surface has two main features: continents and ocean basins. Continents are large land areas. Ocean basins extend from the edges of continents to the ocean floor and into deep trenches. Continents are much older than ocean basins. Some rocks on the continents are billions of years old. Ocean basins are only millions of years old at their oldest. Because the continents are so old, a lot has happened to them! As we view the land around us we see landforms. Landforms are physical features on Earths surface. Landforms are introduced in this section but will be discussed more in later chapters. Constructive forces cause landforms to grow. Lava flowing into the ocean can build land outward. A volcano can be a constructive force. Destructive forces may blow landforms apart. A volcano blowing its top off is a destructive force. The destructive forces of weathering and erosion change landforms more slowly. Over millions of years, mountains are worn down by rivers and streams. Constructive and destructive forces work together to create landforms. Constructive forces create mountains and erosion may wear them away. Mountains are very large landforms. Mountains may wear away into a high flat area called a plateau, or a lower-lying plain. Interior plains are in the middle of continents. Coastal plains are on the edge of a continent, where it meets the ocean. Rivers and streams flow across continents. They cut away at rock, forming river valleys (Figure 2.8). These are | text | null |
L_0037 | introduction to earths surface | T_0372 | If you take away the water in the oceans (Figure 2.6), Earth looks really different. You see that the surface has two main features: continents and ocean basins. Continents are large land areas. Ocean basins extend from the edges of continents to the ocean floor and into deep trenches. Continents are much older than ocean basins. Some rocks on the continents are billions of years old. Ocean basins are only millions of years old at their oldest. Because the continents are so old, a lot has happened to them! As we view the land around us we see landforms. Landforms are physical features on Earths surface. Landforms are introduced in this section but will be discussed more in later chapters. Constructive forces cause landforms to grow. Lava flowing into the ocean can build land outward. A volcano can be a constructive force. Destructive forces may blow landforms apart. A volcano blowing its top off is a destructive force. The destructive forces of weathering and erosion change landforms more slowly. Over millions of years, mountains are worn down by rivers and streams. Constructive and destructive forces work together to create landforms. Constructive forces create mountains and erosion may wear them away. Mountains are very large landforms. Mountains may wear away into a high flat area called a plateau, or a lower-lying plain. Interior plains are in the middle of continents. Coastal plains are on the edge of a continent, where it meets the ocean. Rivers and streams flow across continents. They cut away at rock, forming river valleys (Figure 2.8). These are | text | null |
L_0037 | introduction to earths surface | T_0372 | If you take away the water in the oceans (Figure 2.6), Earth looks really different. You see that the surface has two main features: continents and ocean basins. Continents are large land areas. Ocean basins extend from the edges of continents to the ocean floor and into deep trenches. Continents are much older than ocean basins. Some rocks on the continents are billions of years old. Ocean basins are only millions of years old at their oldest. Because the continents are so old, a lot has happened to them! As we view the land around us we see landforms. Landforms are physical features on Earths surface. Landforms are introduced in this section but will be discussed more in later chapters. Constructive forces cause landforms to grow. Lava flowing into the ocean can build land outward. A volcano can be a constructive force. Destructive forces may blow landforms apart. A volcano blowing its top off is a destructive force. The destructive forces of weathering and erosion change landforms more slowly. Over millions of years, mountains are worn down by rivers and streams. Constructive and destructive forces work together to create landforms. Constructive forces create mountains and erosion may wear them away. Mountains are very large landforms. Mountains may wear away into a high flat area called a plateau, or a lower-lying plain. Interior plains are in the middle of continents. Coastal plains are on the edge of a continent, where it meets the ocean. Rivers and streams flow across continents. They cut away at rock, forming river valleys (Figure 2.8). These are | text | null |
L_0037 | introduction to earths surface | T_0373 | The ocean basin begins where the ocean meets the land. The continental margin begins at the shore and goes down to the ocean floor. It includes the continental shelf, slope, and rise. The continental shelf is part of the continent, but it is underwater today. It is about 100-200 meters deep, much shallower than the rest of the ocean. The continental shelf usually goes out about 100 to 200 kilometers from the shore (Figure 2.9). The continental slope is the slope that forms the edge of the continent. It is seaward of the continental shelf. In some places, a large pile of sediments brought from rivers creates the continental rise. The continental rise ends at the Besides seamounts, there are long, very tall (about 2 km) mountain ranges. These ranges are connected so that they form huge ridge systems called mid-ocean ridges (Figure 2.11). The mid-ocean ridges form from volcanic eruptions. Lava from inside Earth breaks through the crust and creates the mountains. The deepest places of the ocean are the ocean trenches. Many trenches line the edges of the Pacific Ocean. The Mariana Trench is the deepest place in the ocean. (Figure 2.12). At about 11 km deep, it is the deepest place on Earth! To compare, the tallest place on Earth, Mount Everest, is less than 9 km tall. | text | null |
L_0037 | introduction to earths surface | T_0373 | The ocean basin begins where the ocean meets the land. The continental margin begins at the shore and goes down to the ocean floor. It includes the continental shelf, slope, and rise. The continental shelf is part of the continent, but it is underwater today. It is about 100-200 meters deep, much shallower than the rest of the ocean. The continental shelf usually goes out about 100 to 200 kilometers from the shore (Figure 2.9). The continental slope is the slope that forms the edge of the continent. It is seaward of the continental shelf. In some places, a large pile of sediments brought from rivers creates the continental rise. The continental rise ends at the Besides seamounts, there are long, very tall (about 2 km) mountain ranges. These ranges are connected so that they form huge ridge systems called mid-ocean ridges (Figure 2.11). The mid-ocean ridges form from volcanic eruptions. Lava from inside Earth breaks through the crust and creates the mountains. The deepest places of the ocean are the ocean trenches. Many trenches line the edges of the Pacific Ocean. The Mariana Trench is the deepest place in the ocean. (Figure 2.12). At about 11 km deep, it is the deepest place on Earth! To compare, the tallest place on Earth, Mount Everest, is less than 9 km tall. | text | null |
L_0037 | introduction to earths surface | T_0373 | The ocean basin begins where the ocean meets the land. The continental margin begins at the shore and goes down to the ocean floor. It includes the continental shelf, slope, and rise. The continental shelf is part of the continent, but it is underwater today. It is about 100-200 meters deep, much shallower than the rest of the ocean. The continental shelf usually goes out about 100 to 200 kilometers from the shore (Figure 2.9). The continental slope is the slope that forms the edge of the continent. It is seaward of the continental shelf. In some places, a large pile of sediments brought from rivers creates the continental rise. The continental rise ends at the Besides seamounts, there are long, very tall (about 2 km) mountain ranges. These ranges are connected so that they form huge ridge systems called mid-ocean ridges (Figure 2.11). The mid-ocean ridges form from volcanic eruptions. Lava from inside Earth breaks through the crust and creates the mountains. The deepest places of the ocean are the ocean trenches. Many trenches line the edges of the Pacific Ocean. The Mariana Trench is the deepest place in the ocean. (Figure 2.12). At about 11 km deep, it is the deepest place on Earth! To compare, the tallest place on Earth, Mount Everest, is less than 9 km tall. | text | null |
L_0038 | modeling earths surface | T_0374 | Imagine you are going on a road trip. Perhaps you are going on vacation. How do you know where to go? Most likely, you will use a map. A map is a picture of specific parts of Earths surface. There are many types of maps. Each map gives us different information. Lets look at a road map, which is the probably the most common map that you use (Figure 2.13). | text | null |
L_0038 | modeling earths surface | T_0375 | Look for the legend on the top left side of the map. It explains how this map records different features. You can see the following: The boundaries of the state show its shape. Black dots represent the cities. Each city is named. The size of the dot represents the population of the city. Red and brown lines show major roads that connect the cities. Blue lines show rivers. Their names are written in blue. Blue areas show lakes and other waterways the Gulf of Mexico, Biscayne Bay, and Lake Okeechobee. Names for bodies of water are also written in blue. A line or scale of miles shows the distance represented on the map an inch or centimeter on the map represents a certain amount of distance (miles or kilometers). The legend explains other features and symbols on the map. It is the convention for north to be at the top of a map. For this reason, a compass rose is not needed on most maps. You can use this map to find your way around Florida and get from one place to another along roadways. | text | null |
L_0038 | modeling earths surface | T_0376 | There are many other types of maps besides road maps. Some examples include: Political or geographic maps show the outlines and borders of states and/or countries. Satellite view maps show terrains and vegetation forests, deserts, and mountains. Relief maps show elevations of areas, but usually on a larger scale, such as the whole Earth, rather than a local area. Topographic maps show detailed elevations of features on the map. Climate maps show average temperatures and rainfall. Precipitation maps show the amount of rainfall in different areas. Weather maps show storms, air masses, and fronts. Radar maps show storms and rainfall. Geologic maps detail the types and locations of rocks found in an area. These are but a few types of maps that various Earth scientists might use. You can easily carry a map around in your pocket or bag. Maps are easy to use because they are flat or two-dimensional. However, the world is three- dimensional. So, how do map makers represent a three-dimensional world on flat paper? | text | null |
L_0038 | modeling earths surface | T_0377 | Earth is a round, three-dimensional ball. In a small area, Earth looks flat, so it is not hard to make accurate maps of a small place. When map makers want to map the round Earth on flat paper, they use projections. What happens if you try to flatten out the skin of a peeled orange? Or if you try to gift wrap a soccer ball? To flatten out, the orange peel must rip and its shape must become distorted. To wrap around object with flat paper requires lots of extra cuts and folds. A projection is a way to represent Earths curved surface on flat paper (Figure 2.14). There are many types of projections. Each uses a different way to change three dimensions into two dimensions. There are two basic methods that the map maker uses in projections: The map maker slices the sphere in some way and unfolds it to make a flat map, like flattening out an orange peel. The map maker can look at the sphere from a certain point and then translate this view onto a flat paper. Lets look at a few commonly used projections. | text | null |
L_0038 | modeling earths surface | T_0378 | In 1569, Gerardus Mercator (1512-1594) (Figure 2.15) figured out a way to make a flat map of our round world, called the Mercator projection (Figure 2.16). Imagine wrapping the round, ball-shaped Earth with a big, flat piece of paper. First you make a tube or a cylinder. The cylinder will touch Earth at its fattest part, the equator. The equator is the imaginary line running horizontally around the middle of Earth. The poles are the farthest points from the cylinder. If you shine a light from the inside of your model Earth out to the cylinder, the image projected onto the paper is a Mercator projection. Where does the projection represent Earth best? Where is it worst? Your map would be most correct at the equator. The shapes and sizes of continents become more stretched out near the poles. Early sailors and navigators found the Mercator map useful because most explorations were located near the equator. Many world maps still use the Mercator projection. The Mercator projection is best within 15 degrees north or south of the equator. Landmasses or countries outside that zone get stretched out of shape. The further the feature is from the equator, the more out of shape it is stretched. For example, if you look at Greenland on a globe, you see it is a relatively small country near the North Pole. Yet, on a Mercator projection, Greenland looks almost as big the United States. Because Greenland is closer to the pole, the continents shape and size are greatly increased. The United States is closer to its true dimensions. In a Mercator projection, all compass directions are straight lines. This makes it a good type of map for navigation. The top of the map is north, the bottom is south, the left side is west and the right side is east. However, because it is a flat map of a curved surface, a straight line on the map is not the shortest distance between the two points it connects. | text | null |
L_0038 | modeling earths surface | T_0378 | In 1569, Gerardus Mercator (1512-1594) (Figure 2.15) figured out a way to make a flat map of our round world, called the Mercator projection (Figure 2.16). Imagine wrapping the round, ball-shaped Earth with a big, flat piece of paper. First you make a tube or a cylinder. The cylinder will touch Earth at its fattest part, the equator. The equator is the imaginary line running horizontally around the middle of Earth. The poles are the farthest points from the cylinder. If you shine a light from the inside of your model Earth out to the cylinder, the image projected onto the paper is a Mercator projection. Where does the projection represent Earth best? Where is it worst? Your map would be most correct at the equator. The shapes and sizes of continents become more stretched out near the poles. Early sailors and navigators found the Mercator map useful because most explorations were located near the equator. Many world maps still use the Mercator projection. The Mercator projection is best within 15 degrees north or south of the equator. Landmasses or countries outside that zone get stretched out of shape. The further the feature is from the equator, the more out of shape it is stretched. For example, if you look at Greenland on a globe, you see it is a relatively small country near the North Pole. Yet, on a Mercator projection, Greenland looks almost as big the United States. Because Greenland is closer to the pole, the continents shape and size are greatly increased. The United States is closer to its true dimensions. In a Mercator projection, all compass directions are straight lines. This makes it a good type of map for navigation. The top of the map is north, the bottom is south, the left side is west and the right side is east. However, because it is a flat map of a curved surface, a straight line on the map is not the shortest distance between the two points it connects. | text | null |
L_0038 | modeling earths surface | T_0379 | Instead of a cylinder, you could wrap the flat paper into a cone. Conic map projections use a cone shape to better represent regions near the poles (Figure 2.17). Conic projections are best where the cone shape touches the globe. This is along a line of latitude, usually the equator. | text | null |
L_0038 | modeling earths surface | T_0380 | What if want to wrap a different approach? Lets say you dont want to wrap a flat piece of paper around a round object? You could put a flat piece of paper right on the area that you want to map. This type of map is called a gnomonic map projection (Figure 2.18). The paper only touches Earth at one point. The sizes and shapes of countries near that point are good. The poles are often mapped this way to avoid distortion. A gnomic projection is best for use over a small area. | text | null |
L_0038 | modeling earths surface | T_0380 | What if want to wrap a different approach? Lets say you dont want to wrap a flat piece of paper around a round object? You could put a flat piece of paper right on the area that you want to map. This type of map is called a gnomonic map projection (Figure 2.18). The paper only touches Earth at one point. The sizes and shapes of countries near that point are good. The poles are often mapped this way to avoid distortion. A gnomic projection is best for use over a small area. | text | null |
L_0038 | modeling earths surface | T_0381 | In 1963, Arthur Robinson made a map with more accurate sizes and shapes of land areas. He did this using mathematical formulas. The formulas could directly translate coordinates onto the map. This type of projection is shaped like an oval rather than a rectangle (Figure 2.19). Robinsons map is more accurate than a Mercator projection. The shapes and sizes of continents are closer to true. Robinsons map is best within 45 degrees of the equator. Distances along the equator and the lines parallel to it are true. However, the scales along each line of latitude are different. In 1988, the National Geographic Society began to use Robinsons projection for its world maps. Whatever map projection is used, maps help us find places and to be able to get from one place to another. So how do you find your location on a map? | text | null |
L_0038 | modeling earths surface | T_0382 | Most maps use a grid of lines to help you to find your location. This grid system is called a geographic coordinate system. Using this system you can define your location by two numbers, latitude and longitude. Both numbers are angles between your location, the center of Earth, and a reference line (Figure 2.20). | text | null |
L_0038 | modeling earths surface | T_0383 | Lines of latitude circle around Earth. The equator is a line of latitude right in the middle of the planet. The equator is an equal distance from both the North and South Pole. If you know your latitude, you know how far you are north or south of the equator. | text | null |
L_0038 | modeling earths surface | T_0384 | Lines of longitude are circles that go around Earth from pole to pole, like the sections of an orange. Lines of longitude start at the Prime Meridian. The Prime Meridian is a circle that runs north to south and passes through Greenwich, England. Longitude tells you how far you are east or west from the Prime Meridian (Figure 2.21). You can remember latitude and longitude by doing jumping jacks. When your hands are above your head and your feet are together, say longitude (your body is long!). When you put your arms out to the side horizontally, say latitude (your head and arms make a cross, like the t in latitude). While you are jumping, your arms are going the same way as each of these grid lines: horizontal for latitude and vertical for longitude. | text | null |
L_0038 | modeling earths surface | T_0385 | If you know the latitude and longitude of a place, you can find it on a map. Simply place one finger on the latitude on the vertical axis of the map. Place your other finger on the longitude along the horizontal axis of the map. Move your fingers along the latitude and longitude lines until they meet. For example, say the location you want to find is at 30o N and 90o W. Place your right finger along 30o N at the right of the map. Place your left finger along the bottom at 90o W. Move your fingers along the lines until they meet. Your location should be near New Orleans, Louisiana, along the Gulf coast of the United States. What if you want to know the latitude and longitude of your location? If you know where you are on a map, point to the place with your fingers. Take one finger and move it along the latitude line to find your latitude. Then move another finger along the longitude line to find your and longitude. | text | null |
L_0038 | modeling earths surface | T_0386 | You can also use a polar coordinate system. Your location is marked by an angle and distance from some reference point. The angle is usually the angle between your location, the reference point, and a line pointing north. The distance is given in meters or kilometers. To find your location or to move from place to place, you need a map, a compass, and some way to measure your distance, such as a range finder. Suppose you need to go from your location to a marker that is 20o E and 500 m from your current position. You must do the following: Use the compass and compass rose on the map to orient your map with north. Use the compass to find which direction is 20o E. Walk 500 meters in that direction to reach your destination. Polar coordinates are used in a sport called orienteering. People who do orienteering use a compass and a map with polar coordinates. Participants find their way along a course across wilderness terrain (Figure 2.22). They move to various checkpoints along the course. The winner is the person who completes the course in the fastest time. | text | null |
L_0038 | modeling earths surface | T_0387 | Earth is a sphere and so is a globe. A globe is the best way to make a map of the whole Earth. Because both the planet and a globe have curved surfaces, the sizes and shapes of countries are not distorted. Distances are true to scale. (Figure 2.23). Globes usually have a geographic coordinate system and a scale. The shortest distance between two points on a globe is the length of the portion of a circle that connects them. Globes are difficult to make and carry around. They also cannot be enlarged to show the details of any particular area. Globes are best sitting on your desk for reference. Google Earth is a neat site to download to your computer. This is a link that you can follow to get there: http://w tilt your image and lots more. | text | null |
L_0039 | topographic maps | T_0388 | Mapping is an important part of Earth Science. Topographic maps use a line, called a contour line, to show different elevations on a map. Contour lines show the location of hills, mountains and valleys. A regular road map shows where a road goes. But a road map doesnt show if the road goes over a mountain pass or through a valley. A topographic map shows you the features the road is going through or past. Lets look at topographic maps. Look at this view of the Swamp Canyon Trail in Bryce Canyon National Park, Utah (Figure 2.25). You can see the rugged canyon walls and valley below. The terrain has many steep cliffs with high and low points between the cliffs. Now look at the same section of the visitors map (Figure 2.26). You can see a green line that is the main road. The black dotted lines are trails. You see some markers for campsites, a picnic area, and a shuttle bus stop. The map does not show the height of the terrain. Where are the hills and valleys located? What is Natural Bridge? How high are the canyon walls? Which way do streams flow? A topographic map represents the elevations in an area (Figure 2.27). We mentioned topographic maps in the section on orienteering above. | text | null |
L_0039 | topographic maps | T_0388 | Mapping is an important part of Earth Science. Topographic maps use a line, called a contour line, to show different elevations on a map. Contour lines show the location of hills, mountains and valleys. A regular road map shows where a road goes. But a road map doesnt show if the road goes over a mountain pass or through a valley. A topographic map shows you the features the road is going through or past. Lets look at topographic maps. Look at this view of the Swamp Canyon Trail in Bryce Canyon National Park, Utah (Figure 2.25). You can see the rugged canyon walls and valley below. The terrain has many steep cliffs with high and low points between the cliffs. Now look at the same section of the visitors map (Figure 2.26). You can see a green line that is the main road. The black dotted lines are trails. You see some markers for campsites, a picnic area, and a shuttle bus stop. The map does not show the height of the terrain. Where are the hills and valleys located? What is Natural Bridge? How high are the canyon walls? Which way do streams flow? A topographic map represents the elevations in an area (Figure 2.27). We mentioned topographic maps in the section on orienteering above. | text | null |
L_0039 | topographic maps | T_0389 | Contour lines connect all the points on the map that have the same elevation. Lets take a closer look at this (Figure Each contour line represents a specific elevation. The contour line connects all the points that are at the same elevation. Every fifth contour line is made bold. The bold contour lines have numbers to show elevation. Contour lines run next to each other and NEVER cross one another. If the lines crossed it would mean that one place had two different elevations. This cannot happen. | text | null |
L_0039 | topographic maps | T_0390 | Since each contour line represents a specific elevation, two different contour are separated by the same difference in elevation (e.g. 20 ft or 100 ft.). This difference between contour lines is called the contour interval. You can calculate the contour interval by following these steps: a. Take the difference in elevation between 2 bold lines. b. Divide that difference by the number of contour lines between them. Imagine that the difference between two bold lines is 100 feet and there are five lines between them. What is the contour interval? If you answered 20 feet, then you are correct (100 ft/5 lines = 20 ft between lines). The legend on the map also gives the contour interval. | text | null |
L_0039 | topographic maps | T_0391 | How does a topographic map tell you about the terrain? Lets consider the following principles: 1. The spacing of contour lines shows the slope of the land. Contour lines that are close together indicate a steep slope. This is because the elevation changes quickly in a small area. Contour lines that seem to touch indicate a very steep slope, like a cliff. When contour lines are spaced far apart the slope is gentle. So contour lines help us see the three-dimensional shape of the land. Look at the topographic map of Stowe, Vermont (Figure 2.28). There is a steep hill rising just to the right of the city of Stowe. You can tell this because the contour lines there are closely spaced. The contour lines also show that the hill has a sharp rise of about 200 feet. Then the slope becomes less steep toward the right. 2. Concentric circles indicate a hill. Figure 2.29 shows another side of the topographic map of Stowe, Vermont. When contour lines form closed loops, there is a hill. The smallest loops are the higher elevations on the hill. The larger loops encircling the smaller loops are downhill. If you look at the map, you can see Cady Hill in the lower left and another, smaller hill in the upper right. 3. Hatched concentric circles indicate a depression. The hatch marks are short, perpendicular lines inside the circle. The innermost hatched circle represents the deepest part of the depression. The outer hatched circles represent higher elevations (Figure 2.30). 4. V-shaped portions of contour lines indicate stream valleys. The V shape of the contour lines point uphill. There is a V shape because the stream channel passes through the point of the V. The open end of the V represents the downstream portion. A blue line indicates that there is water running through the valley. If there is not a blue line the V pattern indicates which way water flows. In Figure 2.31, you can see examples of V-shaped markings. Try to find the direction a stream flows. 5. Like other maps, topographic maps have a scale so that you can find the horizontal distance. You can use the horizontal scale to calculate the slope of the land (vertical height/horizontal distance). Common scales used in United States Geological Service (USGS) maps include the following: 1:24,000 scale - 1 inch = 2000 ft 1:100,000 scale - 1 inch = 1.6 miles 1:250,000 scale - 1 inch = 4 miles Including contour lines, contour intervals, circles, and V-shapes allows a topographic map to show three-dimensional information on a flat piece of paper. A topographic map gives us a good idea of the shape of the land. | text | null |
L_0039 | topographic maps | T_0391 | How does a topographic map tell you about the terrain? Lets consider the following principles: 1. The spacing of contour lines shows the slope of the land. Contour lines that are close together indicate a steep slope. This is because the elevation changes quickly in a small area. Contour lines that seem to touch indicate a very steep slope, like a cliff. When contour lines are spaced far apart the slope is gentle. So contour lines help us see the three-dimensional shape of the land. Look at the topographic map of Stowe, Vermont (Figure 2.28). There is a steep hill rising just to the right of the city of Stowe. You can tell this because the contour lines there are closely spaced. The contour lines also show that the hill has a sharp rise of about 200 feet. Then the slope becomes less steep toward the right. 2. Concentric circles indicate a hill. Figure 2.29 shows another side of the topographic map of Stowe, Vermont. When contour lines form closed loops, there is a hill. The smallest loops are the higher elevations on the hill. The larger loops encircling the smaller loops are downhill. If you look at the map, you can see Cady Hill in the lower left and another, smaller hill in the upper right. 3. Hatched concentric circles indicate a depression. The hatch marks are short, perpendicular lines inside the circle. The innermost hatched circle represents the deepest part of the depression. The outer hatched circles represent higher elevations (Figure 2.30). 4. V-shaped portions of contour lines indicate stream valleys. The V shape of the contour lines point uphill. There is a V shape because the stream channel passes through the point of the V. The open end of the V represents the downstream portion. A blue line indicates that there is water running through the valley. If there is not a blue line the V pattern indicates which way water flows. In Figure 2.31, you can see examples of V-shaped markings. Try to find the direction a stream flows. 5. Like other maps, topographic maps have a scale so that you can find the horizontal distance. You can use the horizontal scale to calculate the slope of the land (vertical height/horizontal distance). Common scales used in United States Geological Service (USGS) maps include the following: 1:24,000 scale - 1 inch = 2000 ft 1:100,000 scale - 1 inch = 1.6 miles 1:250,000 scale - 1 inch = 4 miles Including contour lines, contour intervals, circles, and V-shapes allows a topographic map to show three-dimensional information on a flat piece of paper. A topographic map gives us a good idea of the shape of the land. | text | null |
L_0039 | topographic maps | T_0391 | How does a topographic map tell you about the terrain? Lets consider the following principles: 1. The spacing of contour lines shows the slope of the land. Contour lines that are close together indicate a steep slope. This is because the elevation changes quickly in a small area. Contour lines that seem to touch indicate a very steep slope, like a cliff. When contour lines are spaced far apart the slope is gentle. So contour lines help us see the three-dimensional shape of the land. Look at the topographic map of Stowe, Vermont (Figure 2.28). There is a steep hill rising just to the right of the city of Stowe. You can tell this because the contour lines there are closely spaced. The contour lines also show that the hill has a sharp rise of about 200 feet. Then the slope becomes less steep toward the right. 2. Concentric circles indicate a hill. Figure 2.29 shows another side of the topographic map of Stowe, Vermont. When contour lines form closed loops, there is a hill. The smallest loops are the higher elevations on the hill. The larger loops encircling the smaller loops are downhill. If you look at the map, you can see Cady Hill in the lower left and another, smaller hill in the upper right. 3. Hatched concentric circles indicate a depression. The hatch marks are short, perpendicular lines inside the circle. The innermost hatched circle represents the deepest part of the depression. The outer hatched circles represent higher elevations (Figure 2.30). 4. V-shaped portions of contour lines indicate stream valleys. The V shape of the contour lines point uphill. There is a V shape because the stream channel passes through the point of the V. The open end of the V represents the downstream portion. A blue line indicates that there is water running through the valley. If there is not a blue line the V pattern indicates which way water flows. In Figure 2.31, you can see examples of V-shaped markings. Try to find the direction a stream flows. 5. Like other maps, topographic maps have a scale so that you can find the horizontal distance. You can use the horizontal scale to calculate the slope of the land (vertical height/horizontal distance). Common scales used in United States Geological Service (USGS) maps include the following: 1:24,000 scale - 1 inch = 2000 ft 1:100,000 scale - 1 inch = 1.6 miles 1:250,000 scale - 1 inch = 4 miles Including contour lines, contour intervals, circles, and V-shapes allows a topographic map to show three-dimensional information on a flat piece of paper. A topographic map gives us a good idea of the shape of the land. | text | null |
L_0039 | topographic maps | T_0391 | How does a topographic map tell you about the terrain? Lets consider the following principles: 1. The spacing of contour lines shows the slope of the land. Contour lines that are close together indicate a steep slope. This is because the elevation changes quickly in a small area. Contour lines that seem to touch indicate a very steep slope, like a cliff. When contour lines are spaced far apart the slope is gentle. So contour lines help us see the three-dimensional shape of the land. Look at the topographic map of Stowe, Vermont (Figure 2.28). There is a steep hill rising just to the right of the city of Stowe. You can tell this because the contour lines there are closely spaced. The contour lines also show that the hill has a sharp rise of about 200 feet. Then the slope becomes less steep toward the right. 2. Concentric circles indicate a hill. Figure 2.29 shows another side of the topographic map of Stowe, Vermont. When contour lines form closed loops, there is a hill. The smallest loops are the higher elevations on the hill. The larger loops encircling the smaller loops are downhill. If you look at the map, you can see Cady Hill in the lower left and another, smaller hill in the upper right. 3. Hatched concentric circles indicate a depression. The hatch marks are short, perpendicular lines inside the circle. The innermost hatched circle represents the deepest part of the depression. The outer hatched circles represent higher elevations (Figure 2.30). 4. V-shaped portions of contour lines indicate stream valleys. The V shape of the contour lines point uphill. There is a V shape because the stream channel passes through the point of the V. The open end of the V represents the downstream portion. A blue line indicates that there is water running through the valley. If there is not a blue line the V pattern indicates which way water flows. In Figure 2.31, you can see examples of V-shaped markings. Try to find the direction a stream flows. 5. Like other maps, topographic maps have a scale so that you can find the horizontal distance. You can use the horizontal scale to calculate the slope of the land (vertical height/horizontal distance). Common scales used in United States Geological Service (USGS) maps include the following: 1:24,000 scale - 1 inch = 2000 ft 1:100,000 scale - 1 inch = 1.6 miles 1:250,000 scale - 1 inch = 4 miles Including contour lines, contour intervals, circles, and V-shapes allows a topographic map to show three-dimensional information on a flat piece of paper. A topographic map gives us a good idea of the shape of the land. | text | null |
L_0039 | topographic maps | T_0392 | As we mentioned above, topographic maps show the shape of the land. You can determine a lot of information about the landscape using a topographic map. These maps are invaluable for Earth scientists. | text | null |
L_0039 | topographic maps | T_0393 | Earth scientists use topographic maps for many things: Describing and locating surface features, especially geologic features. Determining the slope of the Earths surface. Determining the direction of flow for surface water, groundwater, and mudslides. Hikers, campers, and even soldiers use topographic maps to locate their positions in the field. Civil engineers use topographic maps to determine where roads, tunnels, and bridges should go. Land use planners and architects use topographic maps when planning development projects, such as housing projects, shopping malls, and roads. | text | null |
L_0039 | topographic maps | T_0394 | Oceanographers use a type of topographic map that shows water depths (Figure 2.32). On this map, the contour lines represent depth below the surface. Therefore, high numbers are deeper depths and low numbers are shallow depths. These maps are made from depth soundings or sonar data. They help oceanographers understand the shape of bottoms of lakes, bays, and the ocean. This information also helps boaters navigate safely. | text | null |
L_0039 | topographic maps | T_0395 | A geologic map shows the different rocks that are exposed at the surface of a region. Rock units are shown in a color identified in a key. On the geologic map of the Grand Canyon, for example, different rock types are shown in different colors. Some people call the Grand Canyon layer cake geology because most of the rock units are in layers. Rock units show up on both sides of a stream valley. A geologic map looks very complicated in a region where rock layers have been folded, like the patterns in marble cake. Faults are seen on this geologic map cutting across rock layers. When rock layers are tilted, you will see stripes of each layer on the map. There are symbols on a geologic map that tell you which direction the rock layers slant, and often there is a cut away diagram, called a cross section, that shows what the rock layers look like below the surface. A large-scale geologic map will just show geologic provinces. They do not show the detail of individual rock layers. | text | null |
L_0040 | using satellites and computers | T_0396 | To understand what satellites can do, lets look at an example. One of the deadliest hurricanes in United States history hit Galveston, Texas in 1900. The storm was first spotted at sea on Monday, August 27th , 1900. It was a tropical storm when it hit Cuba on September 3rd . By September 8th , it had intensified to a hurricane over the Gulf of Mexico. It came ashore at Galveston (Figure 2.34). Because there was not advanced warning, more than 8000 people lost their lives. Today, we have satellites with many different types of instruments that orbit the Earth. With these satellites, satellites can see hurricanes form at sea. They can follow hurricanes as they move from far out in the oceans to shore. Weather forecasters can warn people who live along the coasts. These advanced warning give people time to prepare for the storm. They can find a safe place or even evacuate the area, which helps save lives. | text | null |
L_0040 | using satellites and computers | T_0397 | Satellites orbit high above the Earth in several ways. Different orbits are important for viewing different things about the planet. | text | null |
L_0040 | using satellites and computers | T_0398 | A satellite in a geostationary orbit flies above the planet at a distance of 36,000 km. It takes 24 hours to complete one orbit. The satellite and the Earth both complete one rotation in 24 hours. This means that the satellite stays over the same spot. Weather satellites use this type of orbit to observe changing weather conditions over a region. Communications satellites, like satellite TV, use this type of orbit to keep communications going full time. | text | null |
L_0040 | using satellites and computers | T_0399 | Another useful orbit is the polar orbit (Figure 2.35). The satellite orbits at a distance of several hundred kilometers. It makes one complete orbit around the Earth from the North Pole to the South Pole about every 90 minutes. In this same amount of time, the Earth rotates only slightly underneath the satellite. So in less than a day, the satellite can see the entire surface of the Earth. Some weather satellites use a polar orbit to see how the weather is changing globally. Also, some satellites that observe the land and oceans use a polar orbit. | text | null |
L_0040 | using satellites and computers | T_0400 | The National Aeronautics and Space Administration (NASA) has launched a fleet of satellites to study the Earth (Figure 2.36). The satellites are operated by several government agencies, including NASA, the National Oceano- graphic and Atmospheric Administration (NOAA), and the United States Geological Survey (USGS). By using different types of scientific instruments, satellites make many kinds of measurements of the Earth. Some satellites measure the temperatures of the land and oceans. Some record amounts of gases in the atmosphere, such as water vapor and carbon dioxide. Some measure their height above the oceans very precisely. From this information, they can measure sea level. Some measure the ability of the surface to reflect various colors of light. This information tells us about plant life. Some examples of the images from these types of satellites are shown in Figure 2.37. | text | null |
L_0040 | using satellites and computers | T_0400 | The National Aeronautics and Space Administration (NASA) has launched a fleet of satellites to study the Earth (Figure 2.36). The satellites are operated by several government agencies, including NASA, the National Oceano- graphic and Atmospheric Administration (NOAA), and the United States Geological Survey (USGS). By using different types of scientific instruments, satellites make many kinds of measurements of the Earth. Some satellites measure the temperatures of the land and oceans. Some record amounts of gases in the atmosphere, such as water vapor and carbon dioxide. Some measure their height above the oceans very precisely. From this information, they can measure sea level. Some measure the ability of the surface to reflect various colors of light. This information tells us about plant life. Some examples of the images from these types of satellites are shown in Figure 2.37. | text | null |
L_0040 | using satellites and computers | T_0400 | The National Aeronautics and Space Administration (NASA) has launched a fleet of satellites to study the Earth (Figure 2.36). The satellites are operated by several government agencies, including NASA, the National Oceano- graphic and Atmospheric Administration (NOAA), and the United States Geological Survey (USGS). By using different types of scientific instruments, satellites make many kinds of measurements of the Earth. Some satellites measure the temperatures of the land and oceans. Some record amounts of gases in the atmosphere, such as water vapor and carbon dioxide. Some measure their height above the oceans very precisely. From this information, they can measure sea level. Some measure the ability of the surface to reflect various colors of light. This information tells us about plant life. Some examples of the images from these types of satellites are shown in Figure 2.37. | text | null |
L_0040 | using satellites and computers | T_0401 | In order to locate your position on a map, you must know your latitude and your longitude. But you need several instruments to measure latitude and longitude. What if you could do the same thing with only one instrument? Satellites can also help you locate your position on the Earths surface. By 1993, the United States military had launched 24 satellites to help soldiers locate their positions on battlefields. This system of satellites was called the Global Positioning System (GPS). Later, the United States government allowed the public to use this system. Heres how it works. You must have a GPS receiver to use the system (Figure 2.38). You can buy many types of these in stores. The | text | null |
L_0040 | using satellites and computers | T_0402 | Prior to the late 20th and early 21st centuries, mapmakers sent people out in the field to determine the boundaries and locations for various features for maps. State or county borders were used to mark geological features. Today, people in the field use GPS receivers to mark the locations of features. Map-makers also use various satellite images and computers to draw maps. Computers are able to break apart the fine details of a satellite image, store the pieces of information, and put them back together to make a map. In some instances, computers can make 3-D images of the map and even animate them. For example, scientists used computers and satellite images from Mars to create a 3-D image of Mars ice cap (Figure 2.39). The image makes you feel as if you are looking at the ice cap from the surface of Mars. When you link any type of information to a location, you can put together incredibly useful maps and images. The information could be numbers of people living in an area, types of plants or soil, locations of groundwater or levels of rainfall. As long as you can link the information to a position with a GPS receiver, you can store it in a computer for later processing and map-making. This type of mapping is called a Geographic Information System (GIS). Geologists can use GIS to make maps of natural resources. City leaders might link these resources to where people live and help plan the growth of cities or communities. Other types of data can be linked by GIS. For example, Figure 2.40 shows a map of the counties where farmers made insurance claims for crop damage in 2008. Computers have improved how maps are made. They have also increased the amount of information that can be displayed. During the 21st century, computers will be used more and more in mapping. | text | null |
L_0040 | using satellites and computers | T_0402 | Prior to the late 20th and early 21st centuries, mapmakers sent people out in the field to determine the boundaries and locations for various features for maps. State or county borders were used to mark geological features. Today, people in the field use GPS receivers to mark the locations of features. Map-makers also use various satellite images and computers to draw maps. Computers are able to break apart the fine details of a satellite image, store the pieces of information, and put them back together to make a map. In some instances, computers can make 3-D images of the map and even animate them. For example, scientists used computers and satellite images from Mars to create a 3-D image of Mars ice cap (Figure 2.39). The image makes you feel as if you are looking at the ice cap from the surface of Mars. When you link any type of information to a location, you can put together incredibly useful maps and images. The information could be numbers of people living in an area, types of plants or soil, locations of groundwater or levels of rainfall. As long as you can link the information to a position with a GPS receiver, you can store it in a computer for later processing and map-making. This type of mapping is called a Geographic Information System (GIS). Geologists can use GIS to make maps of natural resources. City leaders might link these resources to where people live and help plan the growth of cities or communities. Other types of data can be linked by GIS. For example, Figure 2.40 shows a map of the counties where farmers made insurance claims for crop damage in 2008. Computers have improved how maps are made. They have also increased the amount of information that can be displayed. During the 21st century, computers will be used more and more in mapping. | text | null |
L_0040 | using satellites and computers | T_0403 | 5. What would have happened if there had been satellites during the time of the 1900 Galveston earthquake? 6. What would have happened if there had been no satellites when hurricane Katrina struck the Gulf of Mexico coast in 2005? | text | null |
L_0041 | use and conservation of resources | T_0404 | We need natural resources for just about everything we do. We need them for food and clothing, for building materials and energy. We even need them to have fun. Table 20.1 gives examples of how we use natural resources. Can you think of other ways we use natural resources? Use Vehicles Resources Rubber for tires from rubber trees Steel frames and other metal parts from minerals such as iron Example iron ore Use Electronics Resources Plastic cases from petroleum prod- ucts Glass screens from minerals such as lead Example lead ore Homes Nails from minerals such as iron Timber from trees spruce timber Jewelry Gemstones such as diamonds Minerals such as silver silver ore Food Sunlight, water, and soil Minerals such as phosphorus corn seeds in soil Clothing Wool from sheep Cotton from cotton plants cotton plants Recreation Water for boating and swimming Forests for hiking and camping pine forest Some natural resources are renewable. Others are not. It depends in part on how we use them. | text | null |