World Geography Today Chapter 4 Landforms, Water, and Natural Resources Preview Section 1: Landforms Section 2: The Hydrosphere Section 3: Natural Resources Chapter Wrap-Up World Geography Today Chapter 4 Section 1: Landforms Read to Discover • What physical processes inside Earth built up the land? • What physical processes on Earth’s surface wear down the land? • How do these physical processes interact to create landforms? World Geography Today Chapter 4 Section 1: Landforms Plate Tectonics Earth’s crust is made up of moving plates, which spread, collide, and slide laterally past one another. • Spreading plates form oceanic ridges undersea and rift valleys on land. • Colliding plates cause trenches and volcanoes undersea and mountains on land. • Plates sliding laterally cause fractures and earthquakes. World Geography Today Chapter 4 Section 1: Landforms Question By which processes do weathering and erosion wear down the land? World Geography Today Chapter 4 Section 1: Landforms Forces on Earth’s Surface Weathering and erosion shape the land. • Weathering—Slow and hard to detect; includes chemical and physical processes • Erosion—Movement of surface material by water, wind, and ice; wears down land World Geography Today Chapter 4 Section 1: Landforms Weathering and Erosion Erosion Weathering Physical Processes Chemical Processes • Heating and cooling • Freezing and thawing • Tree roots • Substances in air and water Water Wind Ice • Rainfall • Rivers • Waves • Abrasion • Move from one place to another • Glaciers World Geography Today Chapter 4 Section 1: Landforms Tectonics and Surface Forces Interact • Landforms are created through a combination of forces. • For example, a mountain range is formed by tectonics and then weathered and eroded to create valleys, alluvial fans, deltas, and other landforms. World Geography Today Chapter 4 Section 2: The Hydrosphere Read to Discover • In what forms and where do we find water on Earth? • What are the causes and effects of floods? World Geography Today Chapter 4 Section 2: The Hydrosphere Forms of Water • Saltwater—97 percent of world’s water • Freshwater—most frozen in ice caps; less than 1 percent in vapor and liquid form Where Liquid Freshwater Is Found: • Surface Water—in headwaters, tributaries, rivers, lakes, estuaries, wetlands • Groundwater—stored in soil and water table World Geography Today Chapter 4 Section 2: The Hydrosphere Question What roles do evaporation, condensation, and precipitation play in the hydrologic cycle? World Geography Today Chapter 4 Section 2: The Hydrosphere Condensation: As water vapor rises, it forms droplets. Precipitation: Evaporation: Droplets may become heavy enough to fall as rain, snow, or hail. Energy transforms water into vapor. Surface Water World Geography Today Chapter 4 Section 2: The Hydrosphere Floods • Causes—Rivers carrying more water than the stream channels can hold; heavy rains, sudden snow melts; human activity may contribute • Effects—Erosion, loss of vegetation and livestock, death, spread of disease, and property destruction World Geography Today Chapter 4 Section 3: Natural Resources Read to Discover • Why are soil and forests important resources? • What are the concerns about water quality and air quality? • What are some of the ways minerals are used? • What are the main energy resources, and how are they used? World Geography Today Chapter 4 Section 3: Natural Resources Importance of Soil and Forests • Soil and forests are renewable resources. Natural processes continuously replace them. • Soil is crucial for plant life and production of food for humans and for other animals. • Forests protect soil from erosion, provide species habitats, and yield useful products, such as wood, paper, food, medicines, oils, and rubber. World Geography Today Chapter 4 Section 3: Natural Resources Air and Water Quality • Air Pollution—Threatens air supply; dangerous to health of humans, animals, and plants; creates acid rain, which can damage trees and kill fish; damages the ozone layer, which absorbs harmful ultraviolet radiation; may contribute to global warming • Water Pollution—Threatens clean water supply; contributes to shortages World Geography Today Chapter 4 Section 3: Natural Resources AIR POLLUTION Causes: Factories and automobiles burn chemicals, releasing smoke and fumes into the atmosphere. Effects: Acid rain, which can damage trees and kill fish; ozone layer damage; threat to human health; may contribute to global warming World Geography Today Chapter 4 Section 3: Natural Resources Minerals • Minerals are solid substances that come out of the ground, such as metals, rocks, and salt. • Minerals are used in many processes and products, including construction, jewelry, and manufacturing. • Items made from minerals include building materials, airplanes, cans, and glass. Examples: Quartz, limestone, aluminum, gold, gemstones World Geography Today Chapter 4 Section 3: Natural Resources Energy resources are nonrenewable and include fossil fuels—coal, natural gas, and petroleum— and uranium. Uses: • Uranium—Energy for nuclear power • Coal—Heat source; power for steam engines, mills, electricity generation; dye making • Petroleum—Lamp fuel; gasoline; diesel and heating fuel; asphalt; petrochemicals • Natural Gas—Home and industrial heating; fuel World Geography Today Chapter 4 Chapter Wrap-Up Understanding the Main Ideas 1. What are the three types of movements possible at plate boundaries? 2. What are the two physical processes that wear down landforms on Earth’s surface? 3. What process makes some inland lakes salty? 4. What are two short-term effects of air pollution? 5. What is a major drawback of using coal as an energy source?