1. Earth’s Nonliving Resources P.Lobosco

2. Land and Soil Resources More than 6 billion people now inhabit the Earth. Materials removed from the Earth and used by people are called natural resources. Scientists divide the Earth’s natural resources into two groups, nonrenewable and renewable.

3. Nonrenewable Resources Nonrenewable Resources cannot be replaced by nature. Fossil fuels are nonrenewable resources. Minerals, such as copper and iron, are also nonrenewable resources.

4. Renewable Resources Renewable resources S can be replaced by nature. Wood is a renewable resource. Water is a renewable resource. Soil is also a renewable resource, but soil formation is an extremely slow process. Nature can take anywhere from 500 years to 1000 years to replace every 2.5 centimeters of topsoil that have been lost.

5. Land Use One-third of the Earth’s surface is covered by land. Only a small amount of this land can be used for farming or for living space. All land is not suitable for all uses. Land is used for cities, highways, forests, farms and pastures. Even though the population continues to grow, land is a limited resource.

6. Land Use Land is needed for building cities to house the increasing human population. Land is also needed for farming and industry. These needs have to be carefully weighed and balanced. If too much is used for cites, then not enough will be left for farms. Both uses are important.

7. Food Production An increasing population requires an increase in food production. New and improved crop varieties must be developed. Farms must be made more productive wit made fertile.h better growing methods. Land that is unusable for farming must be made fertile. Irrigation is one way to do this. Land is also needed for raising animals and to produce food for the animals.

8. Land Management If limited land resources are to be preserved, land use must be carefully planned and managed. Different land areas are best suited for different purposes.

9. Farm Management. Crops use up nutrients in the soil. When one type of crop is grown on the same land for too long, depletion may result. Farmers need to alternate crops that extract different nutrients. This is known as crop rotation. Contour plowing involves planting crops across the face of a slope of land. In strip cropping, farmers plant strips of low cover crops between strips of other crops. This holds down the soil.

10. Erosion Crops are grown in topsoil. In many areas, topsoil is lost because of erosion. Erosion is the carrying off of soil by water or wind. Poor land management speeds up its process. Worldwide topsoil is being lost 10 times faster than new soil is being formed. Contour plowing, strip cropping and terracing can prevent erosion. Terracing is plowing the slope into a series of level steps to slow down water runoff. Windbreaks prevent wind erosion.

11. Desertification Regions too dry to support crop growth ca support grasslands. These grasslands have traditionally been used for grazing. Too many animals on the land results in overgrazing. Overgrazing leaves the topsoil exposed to wind erosion. Dry grasslands then become deserts. Desertification is taking place all over the world.

12. Land and Soil Reclamation Sometimes land is disturbed to reach valuable minerals. It may be possible for the land to be reclaimed, or restored to its original condition. Land reclamation involves several steps. First, the valuable topsoil is carefully removed and stored. Then the less valuable layers below are stripped away. The needed minerals are removed and shipped. The disturbed soil must be protected from erosion and pollution. Then the layers are put back. The final step is seeding and planting the land.

13. Water Resources Even though water is a renewable resource, there is a limited supply of fresh water. Most of the Earth’s water, 97%, is in the oceans.

14. Uses of Water In the United States, billions of liters of water are used every day. Each person in the United States uses more than 260 liters of water daily. Water is also needed for irrigation. Industry uses more than 60 billion liters of water every day.

15. Water Supply The Earth’ supply of fresh water is constantly renewed by the water cycle. A cycle is a continuous, repeating chain of events. The water cycle is the movement of water from the Earth’s surface to the atmosphere and back to the surface.

16. The Water Cycle In the first step of the water cycle, water on the Earth’s surface is heated by the sun and evaporates. This gas or water vapor rises into the atmosphere. As water vapor rises into the upper atmosphere, it cools, condenses and forms clouds. This is the second step. During the third step of the water cycle, the water falls back to the surface of the Earth as precipitation. Most precipitation falls directly into oceans,lakes, rivers and streams. Some falls to the land and runs off. Eventually it returns to the atmosphere and the cycle continues.

17. Sources of Fresh Water Most of the Earth’s water resources are in oceans, lakes, rivers and streams. Water is also found in the soil as groundwater and frozen as ice in glaciers and polar icecaps. Water in the ocean is too salty to be used. Ice in glaciers is not directly available. So the main sources for fresh water for human use are groundwater, fresh water lakes and rivers.

18. Groundwater More than 300 billion liters of groundwater are taken out of the ground daily in this country for use on farms and in factories. Half the drinking water in the United States comes form groundwater. It takes hundreds of years for groundwater to accumulate. In many areas of the country it is being used faster than it is being replaced. The levels of groundwater are dropping and lakes and rivers may dry up.

19. New Sources of Fresh Water Desalination is the process by which salt is removed from ocean water. Some cities in the United States such as Key West, Florida have built desalination plants.These plants supply 20 million liters of fresh water daily. Icebergs could possible be moved to large coastal cities and mined for fresh water. Scientists are not sure of the environmental effects the movement of glaciers might have.

20. Mineral Resources A mineral is defined as a naturally occurring chemical substance found in soil. Minerals are used to make a variety of products, from silver jewelry to aluminum cans. Minerals are nonrenewable resources. Minerals are either metallic or non metallic.metallic minerals include copper, iron and aluminum. Nonmetallic minerals include quartz, limestone and sulfur.

21. Ores To obtain a useful mineral, the minerals must be mined or removed from the Earth. Deposits of minerals that can be mined at a profit are called ores. If the percentage of a mineral in an ore is high, the ore is called a high-grade ore. Ore are found all over the Earth. The Earth’s crust is a storehouse of minerals.

22. Iron Iron is the most widely used metal extracted from metallic ores. Other substances can be added to iron to make steel. Steel is an alloy, or a substance made of two or more metals. Chromium is added in the steel making process to provide resistance to rusting.

23. Other Minerals Other metals removed from metallic ores include copper, which is used in electric wires and aluminum which is used in cans. Gold and silver, used in jewelry, are also found in metallic ores.

24. Mining and Processing Ores Once mineral deposits have been located, they must be mined. Open-pit mining can have disastrous effect on land and groundwater resources. Mining the ore is the first step. To extract the mineral from the ore, impurities in the ore are removed. A purified mineral remains. The mineral is then processed and sent to the plant to make the final product.

25. Mining the Oceans The minerals in the Earth’s crust have been formed over millions or billions of years. The Earth contains a limited amount of mineral. The present rate of mining cannot continue or the supply will be exhausted. One answer is to reuse or recycle minerals. Another is to find new materials to take their place. Another possibility is the ocean floor. Many minerals such as manganese, nickel, cobalt, and copper have been found on the ocean floor. If these deposits can be mined economically, they may provide a valuable new source of mineral.