World Geography TodayChapter 4 Landforms, Water, and Natural Resources Preview Section 1: LandformsLandforms Section 2: The HydrosphereThe Hydrosphere

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


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?



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.

Plate Tectonics


Question

By which processes do weathering and erosion wear down the land?



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

Forces on Earth’s Surface


Erosion

Chemical Processes

• Substances in air and water

Water• Rainfall• Rivers• Waves

Wind• Abrasion• Move

from one place to another

Ice• Glaciers

Weathering

Physical Processes

• Heating and cooling

• Freezing and thawing

• Tree roots


Weathering and Erosion



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.



Read to Discover

• In what forms and where do we find water on Earth?

• What are the causes and effects of floods?



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


Question

What roles do evaporation, condensation, and precipitation

play in the hydrologic cycle?



Evaporation:Energy transforms water into vapor.

Condensation:As water vapor rises, it forms droplets.

Surface Water

Precipitation:Droplets may become heavy enough to fall as rain, snow, or hail.




• 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

Floods



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?



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.



• 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

Air and Water Quality


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


AIR POLLUTION



• 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

Minerals


Section 3: Natural ResourcesEnergy 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


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?

Documents

World Geography TodayChapter 4 Landforms, Water, and Natural Resources Preview Section 1: LandformsLandforms Section 2: The HydrosphereThe Hydrosphere