CHAPTER 4

Report
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?

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