Study Guide

Earth Science
By
Thomas E. Eveland, PhD

Reviewed by
Tessa Scrobola
CONTENTS
INSTRUCTIONS 1

READING ASSIGNMENTS 5

LESSON 1: EARTH MATERIALS 7

LESSON 2: SCULPTURING EARTH’S SURFACE 14

LESSON 3: FORCES WITHIN AND DECIPHERING

EARTH’S HISTORY 20

LESSON 4: THE GLOBAL OCEAN 30

LESSON 5: EARTH’S DYNAMIC ATMOSPHERE 35

LESSON 6: EARTH’S PLACE IN THE UNIVERSE 48

GRADED PROJECT 54

SELF-CHECK ANSWERS 59

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Contents
INSTRUCTIONS
INTRODUCTION
Welcome to your course, Earth Science. The primary purpose of your textbook,
Foundations of Earth Science, Eighth Edition, is to explain the fundamental processes of
our planet. This course covers a number of topics which are concentrated in four main
categories: geology, meteorology, oceanography, and astronomy.

Geology is the study of Earth, its minerals and rocks, and the many varied processes that
formed our planet and continue to reform it today. Oceanography is the study of Earth’s
oceans. Meteorology is the study of Earth’s atmosphere and astronomy is the study of
Earth’s place in space and all things related. These four elements combined make up the
Earth and are essential in understanding how the world works and how it’s evolving.

COURSE OBJECTIVES
When you complete this course, you’ll be able to do the following:
n Explain the basic differences among the many types of rocks and minerals that
make up Earth’s crust
n Describe how the agents of weathering, such as wind, water, and ice, shape and
reshape the world
n Explain the processes involved in the formation of the great continental land
masses and how they move across Earth’s surface
n Describe the formation of Earth’s oceans, the chemistry of sea water, the forces
behind tides and currents, and how the oceans support life
n Identify the unique mix of gasses that form the various layers of Earth’s atmosphere
n Summarize the events behind the formation of the solar system and how Earth and
the other planets fit into this unique planetary design

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Instructions
COURSE MATERIALS
This course includes the following materials:
1. This study guide, which contains an introduction to your course, plus
n A lesson assignments page with a schedule of study assignments as well as
exams for the lessons you’ll complete during this course
n Individual sections that cover each of the main points of each lesson
n Self-checks and answers to help you assess your understanding of the
material
2. Your course textbook, Foundations of Earth Science, Eighth Edition, which con-
tains the assignment reading material.

YOUR STUDY GUIDE

This study guide is intended to help you better understand the material in your textbook.
It’s not a complete substitute for reading your texts. The material for this course is divided
into four lessons, each of which contains numerous short assignments. Each lesson culmi-
nates with a multiple-choice examination that can be accessed from the student portal. It’s
important to complete the exam for a lesson as you complete the lesson. Trying to study
for multiple lesson examinations at the same time may lead to unnecessary confusion of
terms and concepts.

YOUR TEXTBOOK
Your textbook, Foundations of Earth Science, Eighth Edition, by Frederick K. Lutgens and
Edward J. Tarbuck, contains the material on which you’ll be tested. You need to become
familiar with this textbook before beginning your studies.

Your textbook contains a brief table of contents at the beginning that lists the chapters
and the topics covered in each chapter. Your textbook also contains a SmartFigures fea-
ture identified by the BouncePage icon and includes directions on how to use this feature.
Each chapter is further divided into sections. Your textbook contains a number of addi-
tional resources to enhance your learning and critical thinking at the end of each section,
as well as the end of each chapter.

The textbook’s introduction is an overview of the nature of scientific inquiry, which

involves understanding that science is a process of producing knowledge, and that pro-
cess depends on making careful observations and creating explanations that make sense
of those observations. This process is known as the scientific method.

In the back of your textbook, you’ll find appendices with additional information, a glossary
for key words and definitions, and an index for page number references.

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Instructions
A STUDY PLAN
Think of this study guide as a blueprint for your course. You should read it carefully. Using
the following procedures should help you receive the maximum benefit from your studies:
n Read the lessons in the study guide to introduce you to concepts that are discussed
in the textbook. The lessons emphasize the important material discussed in the text
and provide additional tips or examples to help you grasp the material.
n Note the chapters for each assignment in the textbook and read the assignment in
the textbook to get a general idea of its content. Then study the assignment, paying
attention to all details, especially the main concepts.
n Answer the questions and problems provided in the self-checks in the study guide.
This will serve as a review of the material covered.
n After answering the suggested questions, check your answers with those given in
the back of the study guide. If you miss any questions, review the pages of the text-
book covering those questions. The self-checks are designed to reveal weak points
that you need to review. Do not send the self-check answers to the school. They’re
for you to evaluate your understanding of the material. Complete each assignment
in this way.
n After you’ve completed and checked the self-checks for Lesson 1, go to your stu-
dent portal and complete your first exam.
n Follow this procedure for all lessons. At any time, you can contact your instructor
for information regarding the materials.

Remember to regularly check your student portal. Additional

resources to enhance your learning experience may be posted.

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Instructions
READING ASSIGNMENTS
Lesson 1: EARTH MATERIALS
Read in the study guide: Read in the textbook:

Section 1.1 Introduction and Chapter 1

Section 1.2 Chapter 2

Examination 350623RR

Lesson 2: SCULPTURING EARTH’S SURFACE

Read in the study guide: Read in the textbook:

Section 2.1 Chapter 3

Section 2.2 Chapter 4

Examination 350625RR

Lesson 3: FORCES WITHIN AND DECIPHERING EARTH’S HISTORY

Read in the study guide: Read in the textbook:

Section 3.1 Chapter 5

Section 3.2 Chapter 6
Section 3.3 Chapter 7
Section 3.4 Chapter 8

Examination 350627RR

Lesson 4: THE GLOBAL OCEAN

Read in the study guide: Read in the textbook:

Section 4.1 Chapter 9

Section 4.2 Chapter 10

Examination 350629RR

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Reading Assignments
LESSON 5: EARTH’S DYNAMIC ATMOSPHERE
Read in the study guide: Read in the textbook:

Section 5.1 Chapter 11

Section 5.2 Chapter 12
Section 5.3 Chapter 13
Section 5.4 Chapter 14

Examination 350631RR

LESSON 6: EARTH’S PLACE IN THE UNIVERSE

Read in the study guide: Read in the textbook:

Section 6.1 Chapter 15

Section 6.2 Chapter 16

Examination 35063300

Note: To access and complete any of the examinations for this study guide, click on
the appropriate Take Exam icon on your student portal page. You shouldn’t have to
enter the examination numbers. These numbers are for reference only if you have
reason to contact Student Services.

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Reading Assignments
LESSON 1: EARTH MATERIALS
INTRODUCTION
The basics of Earth Science, which is the name for all the sciences that collectively seek
to understand Earth and its surroundings, are space, geology, oceanography, meteorol-
ogy, and astronomy. The following four spheres make up Earth’s natural environment:
1. Hydrosphere—a dynamic mass of water that’s continuously moving, evaporating
from the oceans to the atmosphere, precipitating to the land, and flowing back to
the ocean
2. Atmosphere—the life-giving gaseous envelope that encircles Earth, providing the
air you breathe and protection from the Sun’s radiation
3. Biosphere—all life on Earth, including bacteria, microorganisms, plants, animals,
and humans
4. Geosphere—the solid Earth that lies beneath the atmosphere and ocean and is
made up of several layers, including the core, the mantle, and the crust

You’ll also learn about some of the issues that involve our physical environment, which
encompasses water, air, soil, and rock, as well as temperature, humidity, and sunlight.
Today, there’s concern about the Earth’s resources. The Earth’s resources are classi-
fied into two categories: renewable (which can be replenished over relatively short time
spans, like forest products) and nonrenewable (which take millions of years to accumu-
late and include iron and natural gas).

SECTION 1.1: MATTER AND MINERALS

Read the following section. Then read the Introduction and Chapter 1 in
your textbook.

Objective
When you complete this section, you’ll be able to explain the composition and struc-
ture of minerals.

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Lesson 1
Introduction to Minerals
Minerals are the basic materials that form Earth’s crust. A mineral is a naturally occur-
ring, inorganic solid with a definite chemical composition and a crystalline structure. The
phrase naturally occurring implies something formed by nature. If something isn’t natu-
rally occurring, it’s synthetic—which means artificial or manmade.

The term inorganic refers to a substance that contains little to no carbon—a substance
that probably wasn’t made by a life-form. The term organic refers to a substance con-
taining a large amount of carbon—a substance that was probably made by a life-form.
A mineral can also be described as something that’s formed by nature and generally not
made by a living thing.

Atoms: Building Blocks of Minerals

Minerals, and all other forms of matter, are made up of microscopic particles, including
protons, neutrons, and electrons. When brought together in the right proportions and fol-
lowing specific universal laws, these subatomic particles form atoms.

An atom is the smallest particle of an element (a substance that can’t be decomposed

into simpler substances by ordinary chemical or physical means) that still retains the
properties of the element. For example, gold is an element. It has specific chemical and
physical qualities that make it gold. If you have a cube of gold and divide it in half and
continue dividing the halves in half you’ll eventually end with an atom of gold.

Atoms are incredibly tiny. It would take several million atoms to fill the space of one letter
on this page. Every atom of gold, or any element, retains the properties of that element.
However, you can’t continue to break down your gold block beyond the individual atom
of gold, because that would mean that you’re breaking apart the atom and, as such, its
properties would change. It would no longer be gold. Figure 1.5 in your textbook is a
periodic table of the elements. The elements are depicted in the table by their smallest
particle (an atom).

Properties of Minerals
Scientists have identified more than 3,500 minerals. Your textbook explains all the differ-
ent properties of these different minerals. For example, some minerals are hard; others
are soft. Some minerals have high luster and shine when polished; others have poor
luster and appear dull. Some minerals cleave, or break along very specific lines, whereas
other minerals shatter, fracturing like broken glass.

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Lesson 1
MINERAL GROUPS
Minerals are divided into silicates and nonsilicates. Silicates contain oxygen and silicone
atoms and are the most abundant group of rock-forming minerals. Nonsilicates are a
group of minerals that don’t contain silicates in their mineral make up.

MINERAL RESOURCES
The final pages in this chapter discuss mineral resources and reserves. Resources are
minerals that can be recovered for use. Reserves are identified deposits from which
minerals can be extracted for a profit.

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 1.1. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, move on to Section
1.2.

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Lesson 1
 Self-Check 1.1
At the end of each section of Earth Science, you’ll be asked to pause and
check your understanding of what you’ve just read by completing a self-
check exercise. Answering these questions will help you review what
you’ve studied so far. Please complete Self-Check 1.1 now.

Respond to the following based on your reading.

1. What five properties must a substance have to be considered a mineral?

2. Identify the three main subatomic particles and describe how they differ.

3. How do atoms, ions, and isotopes differ?

4. If the number of electrons in an atom is 17 and its mass number is 35, calculate
the atom’s atomic number. Also, indicate the number of protons and the number
of neutrons this atom contains.

5. What’s radioactive decay?

6. What properties distinguish minerals from one another?

7. Explain the following phrase: “Every mineral has its own crystalline structure.”

8. Although color is a mineral property, why is it an unreliable method of

identification?

9. How do silicate and nonsilicate minerals differ?

10. What’s the difference between a mineral resource and a mineral reserve?

Check your answers with those at the end of the study guide.

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Lesson 1
SECTION 1.2: ROCKS: MATERIALS
OF THE SOLID EARTH
Read the following section. Then read Chapter 2 in your textbook.

When you complete this section, you’ll be able to explain how rocks transform from
one type to another due to Earth processes.

Earth as a System: The Rock Cycle

The chapter begins with a brief discussion of the rock cycle, which is illustrated in Figure
2.1 in your textbook. This geologic cycle of rock building may require tens, or even
hundreds, of millions of years to complete. Such time spans are sometimes difficult to
comprehend. To understand the rock cycle, you must first learn the three main rock clas-
sifications: igneous, sedimentary, and metamorphic. These three main rock types are
classified by the way they’re formed.

Igneous Rocks: Formed By Fire

Igneous rock is formed when molten rock cools and solidifies. Igneous rock can form
either below or on the Earth’s surface. Molten (or liquefied) rock below the surface is
called magma. Molten rock deposited on the surface through a volcanic eruption is called
lava. Igneous rock that forms below the surface is called intrusive, or plutonic. Igneous
rock that forms on the surface is called extrusive, or volcanic.

Sedimentary Rocks: Compacted and Cemented Sediment

Sedimentary rock is formed from the compacting of sediments, deposited material such
as sand, clay, and other small particles. The main source of most sediment is from the
wearing away of preexisting rock. Sedimentary rocks are layered and form in beds called
strata. Over time, the forces of nature cause these strata to be cemented together into
sedimentary rock.

Sedimentary rock is the only rock type that contains fossils. Fossils are the remains or
traces of once-living organisms from our geologic past. An animal bone, a seashell, or
a piece of wood becomes buried in the sediment. As more sediment collects, the bone,
shell, or wood is sealed into the forming strata. Minerals can replace the once-living
material, or a specific impression is left in the defining sedimentary rock. Fossils are a
critical source of information for scientists trying to understand early life on our planet.

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Lesson 1
Metamorphic Rocks: New Rock from Old
Both igneous and sedimentary rocks can be drawn back under Earth’s surface. Once
underground, they can be exposed to extreme heat and pressure. If these two agents are
severe enough, either or both of these rock types can change, becoming the third type
of rock—metamorphic. The term metamorphic means to change form. Limestone, for
instance, is a sedimentary rock. Once subjected to intense heat and pressure, it becomes
the metamorphic rock known as marble.

Weathering Of Rocks to Form Sediment

Weathering is the disintegration and decomposition of rock at or near Earth’s surface.
The two major categories of weathering are mechanical and chemical. Mechanical
weathering breaks rock down through wind, water, ice, and other physical means.
Chemical weathering breaks rock down through the activity of naturally occurring chem-
icals. Though your textbook discusses these weathering processes separately, keep in
mind that they occur simultaneously in nature.

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 1.2. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, take your exam for
Lesson 1.

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Lesson 1
 Self-Check 1.2
Respond to the following based on your reading.

1. Describe the rock cycle.

2. What’s the difference between magma and lava?

3. What are the three main types of rock found in our planet’s crust?

4. How do intrusive igneous rock and extrusive igneous rock differ?

5. Describe Bowen’s reaction series and explain how it works.

6. Explain how the mechanical weathering process of frost wedging breaks apart
rock. Also, explain how mechanical weathering and chemical weathering differ.

7. What’s sediment and how does it form?

8. Explain why lignite and bituminous coals are classified as sedimentary rocks,
whereas anthracite coal is classified as metamorphic.

9. Which of the three major rock types contains fossils? Why are they found only in
this type of rock?

10. What’s the difference between a foliated metamorphic rock and a nonfoliated met-
amorphic rock?

Check your answers with those in the back of this study guide.

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Lesson 1
LESSON 2: SCULPTURING
EARTH’S SURFACE
INTRODUCTION
In Lesson 2, you’ll study the hydrologic cycle. You’ll learn about how streams and ground-
water are basic links in the continuous cycling of the planet’s water. Chapter 3 will discuss
how springs function and wells recharge. This chapter describes how glaciers are formed
and the erosional and depositional structures they create. Also in this lesson, you’ll dis-
cover why deserts are dry, how the three major categories of rocks are formed, and how
weathering breaks rock into sediment.

SECTION 2.1: LANDSCAPES

FASHIONED BY WATER
Read the following section. Then read Chapter 3 in your textbook.

When you complete this section, you’ll be able to describe the hydrologic cycle.

Earth’s External Processes

The chapter begins with a discussion of the external processes that continually transform
the world around us. These processes include weathering, mass wasting, and erosion.
Weathering is the breakdown and decomposition of rock at or near Earth’s surface. Mass
wasting is the transfer of rock and soil downslope under influence of gravity. Erosion is
the physical removal and transport of material by a mobile agent, such as moving water,
waves, wind, or ice.

The Hydrologic Cycle

The hydrologic cycle (or the water cycle) is illustrated in Figure 3.6 in the textbook. The
water cycle is the movement of water from the atmosphere to the land and back again.

The sun’s energy is the centralized factor that powers the hydrologic cycle. The atmo-
sphere links the oceans and continents through this cycle.

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Lesson 2
Running Water
Running water produces a kind of land-surface circulation system. Streams and rivers
move across the land carrying soil, minerals, and other debris to lakes and oceans.
Running water creates much of the physical landscape. Narrow valleys, wide valleys,
floodplains, natural levees, backswamps, and other surface features are caused by run-
ning water.

Groundwater: Water beneath the Surface

Beneath the surface lie the groundwater supplies. Worldwide, wells and springs provide
water for cities, crops, livestock, business, and industry. In the United States, groundwa-
ter accounts for about 40 percent of the water used for all purposes (except hydroelectric
power generation and power plant cooling).

Due to gravity, water seeps downward through soil and rock until it reaches bedrock.
Gradually, more and more water soaks into the ground, causing the groundwater level to
rise. This creates the area known as the zone of saturation. The upper limit of this zone
is called the water table. Above the water table is the unsaturated zone, where the open
spaces in soil, sediment, and rock aren’t completely filled with water.

Aquifers
In some areas, underground water supplies form subterranean aquifers. Simply put,
these are underground reservoirs. About half of the people in the United States rely on
groundwater taken from wells for drinking.

Along with water, forms of pollution also soak into the ground. These pollutants contami-
nate aquifers, making them unusable. Human sewage, gasoline and oil, toxic chemicals,
and pesticides are just some of the known groundwater contaminants.

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 2.1. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, move on to
Section 2.2.

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Lesson 2
 Self-Check 2.1
Respond to the following based on your reading.

1. Break down, by percentage, how much of Earth’s water exists (1) in the world’s
oceans; (2) in ice sheets and glaciers; and (3) in rivers, streams, groundwater,
and atmosphere.

2. Describe how water moves through the hydrologic cycle.

3. Describe the factors that determine the velocity of stream flow.

4. What’s the capacity of a stream? What factors affect its capacity?

5. What’s the ultimate base level for most streams? Why?

6. Explain how a delta forms.

7. What’s a Yazoo tributary?

8. What’s an aquifer?

9. Describe how the water for hot springs and geysers is heated.

10. What’s the difference between an artesian aquifer and a normal aquifer? Why
does water from an artesian well rise without being pumped?

Check your answers with those in the back of this study guide.

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Lesson 2
SECTION 2.2: GLACIAL AND
ARID LANDSCAPES
Read the following section. Then read Chapter 4 in your textbook.

When you complete this section, you’ll be able to describe how the three major cate-
gories of rocks are formed and how weathering breaks rock into sediment

Glaciers: A Part of Two Basic Cycles

The chapter begins with a discussion of glaciers. The two major types of glaciers are
alpine glaciers and ice sheets. Alpine glaciers generally form on high mountains. (The
term alpine means mountainous.)

Ice sheets, sometimes referred to as continental glaciers, form in polar regions, where
the winters are long and cold. Ice sheets can significantly alter the surface features of a
continent. Much of the topography of North America looks the way it does as a result of
the past glacial period when much of the continent was covered with a giant ice sheet.

Deserts
The second half of the chapter reviews the arid lands of the world. This involves relatively
dry landscapes and deserts. The generic definition of a desert is an area that receives
fewer than 10 inches of precipitation per year and has one third or less of its surface area
covered by plants. However, the concept of dryness is relative. Climatologists define dry
climate as an area in which yearly precipitation is less than the potential loss of water by
evaporation.

Basin and Range: The Evolution of a

Mountainous Desert Landscape
Most deserts are deserts because of their location—too far from an ocean or downwind
of a large mountain range. High mountain ranges force air higher into the atmosphere,
causing it to cool. Cooler air can’t hold as much water, so the water is removed from the
air as rain or snow. By the time the air moves down the other side of the mountain range,
most of its water content has been removed, making it very dry.

Deserts are constantly moving. Wind traveling along the dry ground moves dust and sand
particles, causing blowouts, desert pavement, dunes, and other features.

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Lesson 2
 Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 2.2. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, take your exam for
Lesson 2.

Self-Check 2.2
Respond to the following based on your reading.

1. Describe where and when glaciers form.

2. Where and how are alpine glaciers created? What determines their growth?

3. Describe the formation of glacial ice.

4. List the four types of moraines and describe how they differ.

5. Describe the conditions of an ice age.

(Continued)

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Lesson 2
 Self-Check 2.2
6. Discuss the impact of wind erosion in the desert environment.

7. Why do many desert streams, called ephemeral streams, flow for only a short
period after a rainfall?

8. Alluvial fans, playas, and playa lakes are features associated with the Basin and
Range region of the western United States. Describe these features.

9. Describe the formation of desert pavement.

10. Describe the formation of a dune.

Check your answers with those in the back of this study guide.

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Lesson 2
LESSON 3: FORCES WTIHIN AND
DECIPHERING EARTH’S HISTORY
INTRODUCTION
Lesson 3 discusses how earthquakes occur, seismic waves, and geologic structures.
You’ll also read about the theory of plate tectonics, the concept of the geologic time scale,
and volcanoes and landforms that result from volcanic activity. You’ll learn to differentiate
between the three main groups of volcanoes: shield volcanoes, cinder cones, and com-
posite volcanoes.

SECTION 3.1: PLATE TECTONICS: A

SCIENTIFIC REVOLUTION UNFOLDS
Read the following section. Then read Chapter 5 in your textbook.

When you complete this section, you’ll be able to explain the theory of
plate tectonics.

Continental Drift: An Idea before Its Time

This chapter describes the theory of plate tectonics. Alfred Wegener first developed the
idea, then dubbed continental drift, in the early 1900s. Wegener looked at rock types,
fossils, ocean basins, and similar geologic structures and concluded that the continents
were slowly sliding or drifting. His hypothesis wasn’t given any credit at the time, mainly
because the technology didn’t exist that would later verify it.

Plate Tectonics: The New Paradigm

By the mid1950s and into the 1960s, new technologies were generating more evidence to
support Wegener’s idea of shifting continents. By 1968, enough evidence had been col-
lected that the scientific community accepted the concept of continental drift. However, this
new evidence actually took Wegener’s idea one step further. Today, it’s referred to as plate
tectonics. The theory of plate tectonics states that Earth’s lithosphere, the crust and upper
portion of the mantle, consists of seven major and numerous smaller pieces called plates.

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Lesson 3
Some plates have oceans riding on top of them; others carry continents. Still others
have parts of both or are smaller and hold only portions of oceans and continents. The
current theory adds the idea that these plates are in motion. The plate carrying most of
the continent of North America is moving westward at the rate of a growing fingernail.
Although this might not seem very fast, over tens or hundreds of millions of years it can
be significant.

Some plates are bumping into other plates, causing buckling and the formation of entire
mountain ranges, such as the Rocky Mountains. Other plates are drifting apart, allowing
molten rock from below to ooze upward. Still other plates are sliding at various angles
past one another, causing different geological activity, including earthquakes.

This chapter examines the evidence, piece by piece, supporting the theory of plate tec-
tonics. It also investigates the different plates and discusses how they move. Figure 5.10
in your textbook depicts the Earth’s major lithospheric plates. This chapter also reviews
the internal forces of our planet and how they play into the theory of plate tectonics.

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 3.1. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, move on to
Section 3.2.

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Lesson 3
 Self-Check 3.1
Respond to the following based on your reading.

1. Explain how Mesosaurus fossils found in both South America and Africa play a
role in our understanding of plate tectonics.

2. What are the important differences between the lithosphere and the
asthenosphere?

3. List the major tectonic plates.

4. What properties of the asthenosphere allow lithospheric plates to slide over it

5. Explain the differences between divergent, convergent, and transform fault

boundaries.

6. What’s a subduction zone?

7. Describe some of the major differences between the crust and mantle.

8. Using Figure 5.34 in Chapter 5, contrast the two proposed models for
plate-mantle convection.

Check your answers with those in the back of this study guide.

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Lesson 3
SECTION 3.2: RESTLESS EARTH:
EARTHQUAKES, GEOLOGIC
STRUCTURES, AND MOUNTAIN
BUILDING
Read the following section. Then read Chapter 6 in your textbook.

When you complete this section, you’ll be able to describe seismic waves, rock
deformation, folds, faults, and the movement of mountains.

Earthquakes
Earthquakes are terrifying and dynamic events. Every year people are killed and property
destroyed by this geologic phenomena. Geologists are trying to better understand earth-
quakes, and perhaps someday they’ll be able to accurately predict their occurrence.

Some areas of our planet experience more earthquakes than others. These high-earth-
quake areas tend to be associated with faults, or the areas along plate boundaries. If two
plates are moving against each other, the sides of a fault associated with those plates
will slowly push and pull against the plates. The stress of this slow, grinding movement
involves enormous amounts of energy. Sometimes two plates that are sliding along each
other will become locked. The pressure will begin to build at these locked plates until they
eventually break loose. When this occurs, the plates slide forward or backward with a
powerful jerk, releasing stored energy. The release of energy is felt as shock waves and
vibrations in the Earth. This is an earthquake. Figure 6.5 in your textbook further details
this process.

Studying Earthquake Waves

Seismic waves are a form of energy that’s created when large earthquakes release
large amounts of stored up energy. Seismic waves often have resulting geologic con-
sequences, such as landslides and tsunamis. To predict and prepare for such natural
disasters, people began to study these waves and tried to pinpoint their origin; this
became known as seismology.

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The instruments used to measure seismic waves are called seismographs or seismom-
eters, which measure the duration and intensity of an earthquake on a record called a
seismogram. Two types of waves are recorded:
1. Body waves—waves that travel through the Earth’s interior
2. Surface waves—waves that travel through the rock layers of the Earth’s surface

Geologic Structures
The end of this chapter discusses a variety of geologic features that occur near or along
fault lines due to the shifting and sliding plates. Structures formed by Earth’s constant
movement include:
n VFolds—wavelike undulations in layered rocks that form through deformation in
rocks
n VDomes and basins—large folds that produce “bulls-eye” shaped patterns
n VFaults—fractures in rock with movement or displacement apparent on both sides
n VJoints—fractures in rock where no apparent movement or displacement has
occurred

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 3.2. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, move on to
Section 3.3.

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Lesson 3
 Self-Check 3.2
Respond to the following based on your reading.

1. What’s an earthquake?

2. Define focus and epicenter.

3. Why do earthquakes occur in certain areas and not others?

4. Explain seismology, seismographs, and seismograms.

5. What are the two types of seismic waves?

6. What’s the difference between an anticline and a syncline?

7. What’s orogenesis?

8. What happens when a microcontinent and a volcanic island arc are carried toward
a subduction zone?

Check your answers with those in the back of this study guide.

SECTION 3.3: VOLCANOES AND OTHER

IGNEOUS ACTIVITY
Read the following section. Then read Chapter 7 in your textbook.

When you complete this section, you’ll be able to identify the different types of
volcanoes and landforms that result from volcanic activity.

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The Nature of Volcanic Eruptions
A volcanic eruption is one of the most violent geologic events produced by Earth. During
the last century, eruptions have killed thousands of people and caused billions of dollars
in damage. Some volcanic eruptions occur gently, whereas others explode with all the
force of a nuclear bomb. On May 18, 1980, one of the largest volcanic eruptions in North
America occurred. Mount St. Helens, in the state of Washington, erupted, blowing the
entire north face of the mountain away. Figure 7.1 in your textbook shows before and
after photos of this historic event.

Volcanic Structures and Eruptive Styles

This chapter is all about volcanoes and the internal activities associated with them. Your
book discusses the three main groups of volcanoes:
1. Shield volcanoes
2. Cinder cones
3. Composite cones

Figure 7.12, Figure 7.15, and Figure 7.17 detail the similarities and differences between
the three.

Other Volcanic Landforms

This chapter also reviews some of the other landforms associated with volcanic activities.
Calderas are large collapsed depressions. Lava plateaus are caused by a blanket of low
viscosity basaltic lava flowing from fractures in the crust over a wide area. The fractures,
or cracks, in the crust are called fissures.

Plate Tectonics and Igneous Activity

The chapter concludes by examining volcanic activity along specific plate boundaries. For
instance, Figure 7.35 in your textbook reviews the famous Ring of Fire. This map shows
where some of the world’s major volcanoes are and how they form a ring encircling the
Pacific basin.

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Lesson 3
 Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 3.3. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, move on to Section
3.4.

Self-Check 3.3
Respond to the following based on your reading.

1. What gases are released during a volcanic eruption?

2. List and describe the three types of volcanoes.

3. How does a composite cone form?

4. Describe the pyroclastic materials that are ejected during an eruption.

5. How does a caldera form?

6. Explain the difference between a dike and a sill.

7. What’s the Ring of Fire?

8. What’s a hot spot? How many have been identified? How long have some
persisted?

Check your answers with those in the back of this study guide.

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Lesson 3
SECTION 3.4: GEOLOGIC TIME
Read the following section. Then read Chapter 8 in your textbook.

When you complete this section, you’ll be able to describe the concept of the
geologic time scale.

Catastrophism versus Uniformitarianism

The chapter begins with a brief discussion of catastrophism and uniformitarianism. In the
seventeenth and eighteenth centuries, catastrophism stated that Earth’s landscapes were
developed by great catastrophic events that occurred during short periods of time.

Another idea, uniformitarianism, stated that the physical, chemical, and biological laws
that operate during the present also operated in the past. This idea was advanced by
James Hutton in the late 1700s.

Relative and Numerical Dating

Geologists use two types of dates to interpret Earth history: relative and numerical.
Relative dates attempt to place events into a sequence of formation. Numerical dates
attempt to place the time in years when an event took place.

Fossils
Your textbook describes the importance of fossils for understanding the geologic past.
Fossils were once-living organisms. Knowing what life-forms existed at a particular place
and time helps scientists understand past environmental conditions. Fossils also are
important time indicators. By studying fossils, scientists can study the evolution of an
area or environment.

Radiometric Dating
The process of radiometric dating is a technique that provides a reliable method of cal-
culating the ages of rocks and minerals that contain particular radioactive isotopes.
Radiometric dating has produced thousands of numerical dates for events in our planet’s
history. This procedure has validated many of the geologic predictions of Wegener, Hutton,
Darwin, and others who described Earth as being a much older planet than most believed.

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Lesson 3
 Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 3.4. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, take your exam for
Lesson 3.

Self-Check 3.4
Respond to the following based on your reading.

1. What’s the difference between catastrophism and uniformitarianism?

2. What’s meant by the phrase “the present is the key to the past”?

3. Describe two ways of measuring geologic time.

4. Explain the law of superposition.

5. How do conformable strata and unconformable strata differ?

6. Why are index fossils important?

7. What’s a stable isotope? An unstable isotope?

8. What’s meant by half-life when referring to an isotope?

9. List the eras from oldest to present.

10. What are some of the difficulties in dating the geologic time scale?

Check your answers with those in the back of this study guide.

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Lesson 3
LESSON 4: THE GLOBAL OCEAN
INTRODUCTION
Lesson 4 will explore oceanography which is a composite science that draws upon the
knowledge of biology, chemistry, physics, and geology to study the global ocean. In this
lesson, you’ll study the geography of the oceans and compare the oceans and the conti-
nents. Also discussed are the varied geological features of the seafloor and the ocean’s
circulation patterns. Chapter 10 studies the movements of ocean waters and how this
affects coastal regions.

SECTION 4.1: OCEANS: THE LAST

FRONTIER
Read the following section. Then read Chapter 9 in your textbook.

When you complete this section, you’ll be able to describe the geography of the
oceans and compare the oceans and the continents.

This chapter begins looking into the field of oceanography. Oceanography is a composite
science, meaning that it draws upon the knowledge of biology, chemistry, physics, and
geology to study the global ocean.

The Vast World Oceans

The majority of the ocean is a mystery simply because so much of it is inaccessible. The
island of Hawaii is the weathered top of a massive volcanic mountain with its base on
the sea bottom. The Earth’s largest, flattest features, the abyssal plains, are also part of
the great sea floor. The Pacific Ocean, for instance, is so large that all of the continents
on Earth could easily fit into it with room leftover. The Pacific’s average depth is 3,940
meters, or almost 2½ miles.

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Lesson 4
Composition of Seawater
Seawater is more than just saltwater. It does have salt, about 3.5 percent by weight. This
is called salinity. Along with the different salts, dozens of other elements might be mixed
in. Table 9.1 in your textbook lists some of the components found in seawater.

The Ocean’s Layered Structure

The oceans are also layered. The top part is referred to as the surface mixed zone. This
area receives sunlight, is affected by waves, tides, and surface currents, and holds fairly
high numbers of organisms. Below the surface mixed zone is the transition zone. This
zone is marked by a number of abrupt changes.

One noted change occurs with temperature. There’s a relatively sharp drop in tempera-
ture because the sunlight is absorbed by the surface mixed zone. This is referred to as
the thermocline. This zone also has an abrupt change in salinity referred to as the halo-
cline. The bottom layer of the ocean, which comprises roughly 80 percent of the total
ocean’s area, is the deep ocean. It’s cold, dark, and under great pressure from the other
ocean zones above.

This chapter discusses the multitude of underwater geologic features and describes tech-
niques used to map the deep ocean floor, such as using sonar instruments and satellites
to help explore the ocean floor. The chapter also explains the seafloor sediment cate-
gories which are terrigenous, biogenous, and hydrogenous and how climatologists are
using the seafloor sediments to piece together a climate pattern for our planet.

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 4.1. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, move on to
Section 4.2.

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Lesson 4
 Self-Check 4.1
Respond to the following based on your reading.

1. Of the Pacific, Atlantic, Indian, and Arctic Oceans, which is the largest?

2. Describe the main differences between oceans and continents.

3. What’s the chemical composition of seawater?

4. How large is the surface mixed zone and what are its key characteristics?

5. What key features define the transition zone?

6. The deep ocean makes up what percentage of the global ocean and what are its
key characteristics?

7. Explain what bathymetric techniques are and how they work.

8. What are submarine canyons and turbidity currents?

9. What’s the difference between a seamount and a guyot?

10. Describe the three main types of seafloor sediment.

Check your answers with those in the back of this study guide.

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Lesson 4
SECTION 4.2: THE RESTLESS OCEAN
Read the following section. Then read Chapter 10 in your textbook.

When you complete this section, you’ll be able to describe the varied geological
features of the seafloor.

Surface and Deep Sea Circulation

This chapter reviews moving seawater, including wave action, tidal flow, and large global
oceanic currents. It also presents how and why these movement patterns occur and what
they do for the ocean itself. For example, surface ocean currents occur because of wind
action.

Wind currents flowing across the top of the ocean set the surface waters in motion.
The Coriolis effect (created by the Earth’s rotation on its axis) adds to the movement of
these large oceanic currents. The position of the continents turns, or steers, the surface
currents on a circular pattern. Figure 10.2 in your textbook provides an overview of the
world’s ocean surface currents.

The Shoreline
This chapter describes the various processes that tides and wave action have on
beaches and shorelines. When someone asks you to go to the beach, do you picture
rocky cliffs with waves splashing over half-submerged boulders? Or do you picture wide
expanses of fine, easy-to-walk-on sand with soft waves sliding up the beach? Actually,
both of these are beaches. A beach is a piece of shoreline that’s washed with waves and
affected by tidal movement. Beaches are composed of various types of sediment. The
sizes of the types of sediment that make up a beach can vary greatly, ranging from tiny
sand grains to large boulders.

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Lesson 4
 Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 4.2. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, take your exam for
Lesson 4.

Self-Check 4.2
Respond to the following based on your reading.

1. Explain the processes that drive large surface currents.

2. What’s upwelling and where might it be found?

3. Explain the processes that drive the deep ocean currents.

4. Describe what happens to a wave as it moves from deeper water onto the shore.

5. What’s meant by the phrase “the evolving coastline”?

6. What are groins and why are they built?

7. What’s the difference between an emergent coast and a submerged coast?

8. Why is the gravitational pull of the Moon greater on the Earth than that of the Sun?

9. Explain the difference between a neap tide and a spring tide.

10. What’s a tidal delta and how is it formed?

Check your answers with those in the back of your textbook.

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Lesson 4
LESSON 5: EARTH’S DYNAMIC
ATMOSPHERE
INTRODUCTION
Lesson 5 explores Earth’s atmosphere and the components of the atmosphere. This
lesson explains the difference between weather and climate. It discusses Earth’s motions
and what causes the seasons.

Chapter 11 explains the difference between heat and temperature. It also describes the
three mechanisms of heat transfer. In Chapter 12, you’ll read about moisture, clouds, pre-
cipitation, and how water affects the atmosphere. Chapter 13 describes the atmosphere
in motion and explains air pressure, wind currents, and global wind patterns. Chapter 14
explores weather patterns and severe weather. This chapter also defines air mass and
discusses the difference between cold fronts and warm fronts.

SECTION 5.1: HEATING THE

ATMOSPHERE
Read the following section. Then read Chapter 11 in your textbook.

When you complete this section, you’ll be able to describe the components of
the atmosphere.

Weather and Climate

Weather refers to the conditions of the atmosphere at any particular place and time. Is it
raining or sunny? How hard is the breeze blowing and from what direction? What’s the
temperature?

Climate is the accumulation of weather events over long periods of time. For example,
what are the normal “high” and “low” temperatures for this date? How much rain does
Florida receive in May? How much snow does New York City get for an average winter?
These things all refer to climatic conditions.

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Lesson 5
Composition of the Atmosphere
The two main gases that make up Earth’s atmosphere are oxygen (21 percent) and nitro-
gen (78 percent). The other 1 percent of air is made up of carbon dioxide, argon, and a
number of other variable components such as water vapor and aerosols.

The atmosphere, from ground to outer space, is divided into four major layers:
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere

The layers of the atmosphere are depicted in Figure 11.9 in your textbook.

Energy, Heat, and Temperature

The Earth moves in two ways:
1. Rotation around its axis
2. Orbital rotation around the sun

These movements are what define seasons, solstices, and equinoxes and determine how
much warmth the Earth is given based on its relative position to the sun. While the sun
and Earth have this special relationship, there are also other methods in which the atmo-
sphere generates and absorbs heat.

Mechanisms of Heat Transfer

To fully comprehend how the various processes in the atmosphere actually work, you
must first understand the mechanisms of heat transfer, which are conduction, convec-
tion, and radiation. Conduction refers to the transfer of heat through matter by molecular
activity. Convection refers to the transfer of heat by mass movement or circulation within
a substance. Radiation is the mechanism by which the Sun’s energy reaches our planet.
Radiation is the only way that heat can travel through the vacuum of space and is how
the sun gives energy to the Earth—through solar radiation.

Figure 11.20 in your textbook depicts how incoming solar radiation from the sun is
absorbed by the Earth. Notice that more solar radiation is absorbed through the Earth’s
surface than the surrounding atmosphere. The figure also shows how solar radiation is
dispersed by reflection and scattering.

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Lesson 5
The Greenhouse Effect
In a real greenhouse, the glass allows the short wavelengths from the Sun to pass
through. These wavelengths, upon impacting the interior of the greenhouse, are con-
verted to heat that’s then trapped by the glass. The Earth’s atmosphere contains certain
gases, such as carbon dioxide, methane, water vapor, and others, that are called green-
house gases. These gases catch and hold heat radiating from the surface of the Earth. In
essence, these gases work much like the glass on a greenhouse—hence the name, the
greenhouse effect.

Global Warming
Global warming is an exaggerated greenhouse effect. Due to a number of processes on
Earth—such as deforestation and the excessive burning of coal, oil, and gas—carbon
dioxide and other greenhouse gases are increasing in the atmosphere. The atmosphere
has the potential of holding in more heat. This excess heat is contributing to rising
sea-levels, the development of larger-scale storms, and increases in the frequency and
intensity of heat waves and droughts.

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 5.1. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, move on to
Section 5.2.

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Lesson 5
 Self-Check 5.1
Respond to the following bases on your reading.

1. What’s the difference between weather and climate?

2. List the four different layers of the atmosphere from the ground to outer space and
explain how the temperature changes from layer to layer.

3. What’s the composition of air in the lower atmosphere?

4. Explain Earth’s two principal motions—rotation and revolution. How are day and
night and seasons formed?

5. What’s the difference between conduction and convection?

6. What happens to solar radiation when it reaches Earth’s surface?

7. What’s the greenhouse effect?

8. What are some of the possible consequences of global warming?

9. Explain how altitude, geographic position, cloud cover, and albedo affect atmo-
spheric temperature.

10. Using Figures 11.37 and 11.38 in your textbook, what are the general trends in the
world distribution of temperature?

Check your answers with those in the back of this study guide.

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Lesson 5
SECTION 5.2: MOISTURE, CLOUDS,
AND PRECIPITATION
Read the following section. Then read Chapter 12 in your textbook.

When you complete this section, you’ll be able to list the many ways that water
affects the atmosphere.

Water’s Changes of State

Water is unique in that it can exist in a variety of forms. Water is able to turn into ice when
its molecules are cooled by forming a tight, orderly network. Apply heat and those mole-
cules will begin to move and oscillate, loosening that network and returning water back to
its liquid state. Apply more heat from the environment and some of the molecules will be
able to move so rapidly, they’ll break free from their attractions and escape through the
air as water vapor.

Figure 12.2 in your textbook outlines this process, as well as all the other processes
water molecules can go through to transform from one state to another. It will be espe-
cially useful when discussing atmospheric storms in Chapter 14.

Forms of Precipitation
Because water is able to morph from one state to the next through different environmen-
tal processes, there are also a number of ways in which water affects our atmosphere.

Humidity: Water Vapor in the Air

Humidity is a basic term for the amount of water vapor in the air. Different air masses
(large bodies of air moving west to east) have different relative humidity. Relative
humidity is simply the ratio of the air’s actual water-vapor content to its potential water-va-
por capacity at a given temperature. For example, say that the air is 25°C (77°F).
Meteorologists know that air at this temperature is considered full, or saturated, if it has
20 grams of water vapor per kilogram of air. The instruments tell you the air has only 10
grams of water vapor. You would write this as 10/20, or 50 percent. If the same air had a
reading of 20 grams, you would write this as 20/20, or 100 percent. At 100 percent, the
air is fully saturated, meaning you can expect some form of precipitation.

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Lesson 5
Changes in temperature affect the humidity of the area in different ways, which create
environments for different kinds of weather. Your textbook outlines how temperature
changes, processes of lifting air, and atmospheric stability can be affected by the amount
of water vapor in the air and how it moves through its different forms.

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 5.2. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, move on to Section
5.3.

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Lesson 5
 Self-Check 5.2
Respond to the following based on your reading.

1. List the six processes that change the state of water among gas, liquid, and solid.

2. What’s sublimation and how does it differ from deposition?

3. Explain relative humidity.

4. What’s the dew point?

5. What’s adiabatic temperature change?

6. Describe the four processes that lift air.

7. What’s unstable air?

8. List the three basic cloud forms and describe how they differ.

9. What’s fog?

10. Explain how precipitation forms using the collision-coalescence process.

Check your answer with those in the back of this study guide.

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Lesson 5
SECTION 5.3: THE ATMOSPHERE
IN MOTION
Read the following section. Then read Chapter 13 in your textbook.

When you complete this section, you’ll be able to explain the causes of air pressure,
wind currents, and global wind patterns.

Understanding Air Pressure

Chapter 13 begins with a discussion of atmospheric (air) pressure. Atmospheric pressure
is the pressure, or force, of the air molecules around you. Although you can’t see these air
molecules, they have weight and take up space just like other molecules. Due to the force
of gravity pulling on air molecules, the atmosphere near the surface of Earth is denser—
that means there are more molecules per unit of space. The average air pressure at sea
level is about 1 kilogram per square centimeter, or 14.7 pounds per square inch.

An example used to explain atmospheric pressure can be seen when you move vertically
in the atmosphere. Our bodies are accustomed to the air pressure that exists at sea level.
If you’ve ever climbed a high mountain or flown in an airplane, you might have noticed
the effects of changing air pressure on your eardrums then they pop. When you ascend
to a high altitude, your ears must adjust to the change in pressure. The popping is an
indication that your ears are trying to balance the pressure between the inside of your
head and outside environment.

Wind
Chapter 12 examines the vertical motion of air and the horizontal movement of air, or
wind. Wind is caused by the horizontal differences in air pressure. These differences exist
because of the unequal way the surface of the Earth is heated. Five times more sunlight
strikes the tropics than the poles. The tropical zone is the area between the Tropic of
Capricorn and the Tropic of Cancer, with the equator in the middle.

A quick look at any globe or earth map will show these tropic lines. From the edge of the
tropical zone, going both north and south, you enter the temperate zones. These extend
all the way to the polar zone. Almost all of the United States and Canada (except for a
small area along the very northern edge) is in the northern temperate zone. At both ends
of the globe, there are poles.

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Lesson 5
Wind Currents
The difference in the amount of solar energy striking the Earth from the equator to the
poles determines differences in surface heating. Variations in surface heating cause hori-
zontal atmospheric pressure to vary. This sets up several major wind currents around our
planet, as well as numerous smaller wind patterns.

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 5.3. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, move on to Section
5.4.

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Lesson 5
 Self-Check 5.3
Respond to the following based on your reading.

1. Explain air pressure.

2. What’s a barometer?

3. What are isobars and what do they measure?

4. What causes wind?

5. Explain high- and low-pressure centers.

6. Describe the trade winds.

7. Describe the flow of air in regards to land and sea breezes.

8. Describe the flow of air in mountain-valley environments.

9. Explain the chinook and Santa Ana winds.

10. What does a wind vane do?

Check your answers with those in the back of this study guide.

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Lesson 5
SECTION 5.4: WEATHER PATTERNS
AND SEVERE WEATHER
Read the following section. Then read Chapter 14 in your textbook.

When you complete this section, you’ll be able to identify the factors that produce
weather patterns.

Air Masses
Weather patterns are often the result of an air mass. An air mass is a massive body of air,
generally 1,600 kilometers (1,000 miles) or more across and possibly several kilometers
thick. It’s characterized by a similarity of temperature and moisture at any given altitude.
A typical air mass may take several days to pass. That’s why you might tend to have the
same daily weather for two, three, or even four days followed by a few hours or a day of
stormy weather and then back to several more days of consistent weather.

When fairly consistent weather occurs, it’s the result of passing air masses and is known
as air-mass weather. Air masses are usually characterized by their source of origin. If
they develop over land, they’re called continental (c). If they develop over water, they’re
called maritime (m). If they develop in the cold, high latitudes, then they’re called polar
(P) or arctic (A). If they form in the warm, low latitude tropics, then they’re called tropic
(T). A cP (continental polar) air mass is one that has developed over northern Canada
and contains cold, dry air. An air mass that’s mT (maritime tropical) probably developed
over a warm tropical ocean, such as the Gulf of Mexico. It will contain warm, moist air.

Fronts
Fronts are the boundary lines between air masses. Because no two fronts are the same
temperature or contain the same moisture, air where two fronts meet becomes unstable.
Unstable air often produces storms, because warm, moist air is forced upward.

Storms
This chapter also examines three severe weather types: thunderstorms, tornadoes, and
hurricanes.

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Lesson 5
Thunderstorms
Thunderstorms form when warm, moist air rises in an unstable atmosphere. This pro-
duces a cumulonimbus cloud that may be 12,000 meters or higher. Because of the
significant temperature differences within the cloud itself from top to bottom, it will
develop its own internally circulating winds. Storms also generate heavy rain, thunder,
and lightning. Some storms can even produce damaging hail.

Tornados
Tornadoes are local storms of short duration that contain exceptionally high winds.
They’re violent rotating columns of air. How violent? Table 14.1 shows the Enhanced
Fujita intensity scale. This scale offers six categories for tornado classification. Category
EF-5 is the highest. The United States has had a few EF-5s. Every year there are millions
of dollars in damage and numerous human deaths attributed to tornadoes.

Hurricanes
Most people enjoy the tropics with their soft breezes, warm sunshine, and comfortable
temperatures. However, the tropics are also the breeding ground of the greatest storms
on Earth, with storms that can produce 50-foot waves at sea, winds between 100 and
200 mph, and rainfall amounts of 20 inches or more. They can also reach 600 kilometers
(375 miles) or more across.

Hurricanes begin over hot, tropical waters. They develop rotating columns similar to tor-
nadoes, but many times more massive. The hot water picked up by the rotating wind is
carried high into the atmosphere. There it begins to condensate. Because condensation
releases heat, this energy source strengthens the storm. Generally, hurricanes continue
to grow as long as they stay over hot water. The hotter the water, the bigger and stronger
the storm. Wind damage, heavy rains, and flooding aren’t uncommon devastations asso-
ciated with hurricanes.

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 5.4. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, take your exam for
Lesson 5.

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Lesson 5
 Self-Check 5.4
Respond to the following based on your reading.

1. What’s an air mass?

2. What’s the difference between a cP and an mT air mass?

3. What’s a front?

4. Describe a middle-latitude cyclone.

5. When a dense cold air mass advances into an area occupied by warmer air, the
boundary line is referred to as a cold front. What happens at the point of collision?

6. Describe a thunderstorm.

7. Identify and describe the stages of thunderstorm development.

8. Describe a tornado.

9. Explain the Enhanced Fujita intensity scale.

10. Discuss what a hurricane is and explain how one forms.

Check your answers with those in the back of this study guide.

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Lesson 5
LESSON 6: EARTH’S PLACE
IN THE UNIVERSE
INTRODUCTION
Lesson 6 explores the solar system. You’ll read about how the work of five scientists
impacted our way of thinking about the Earth, the planets, and space. Chapter 15
explains how the planets have two groups based on location, size, and density. The two
groups of planets are terrestrial and Jovian. Chapter 16 will discuss a brief history of the
universe. You’ll also read about the life cycle of a star, the properties of stars, and the
types of galaxies.

SECTION 6.1: THE NATURE

OF THE SOLAR SYSTEM
Read the following section. Then read Chapter 15 in your textbook.

When you complete this section, you’ll be able to explain how the work of scientists
changed our way of thinking about the Earth, the planets, and space.

The Nature of the Solar System

The distance to a nearby star, the speed of light, the potential number of planets in the
galaxy, and the incredible mass of the Sun are large ideas that almost require imagination
to understand. Astronomers study objects so far away that they can’t investigate them
directly. They study events that actually occurred billions of years ago. Your knowledge
of space can’t be derived by direct sampling. You must accumulate data piece by piece,
interpreting it as you go. At some point, suggestions regarding events and objects outside
the realm of direct contact can be developed.

Ancient Astronomy
The first great problem for astronomers was simply trying to explain the motion of Earth.
Many believed that Earth wasn’t moving at all and that the planet was, in fact, the cen-
ter of the universe. This is called the geocentric theory. Eventually, over time and with

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Lesson 6
new ways of thinking, scientists began to understand how the planets, moons, and other
objects move throughout the universe. Try to put yourself into the world of these early
astronomers. Without telescopes or other devices, they were forced to rely on basic
human observation.

The ancient Greeks assumed that Earth must be stationary because (1) people have
no sensation of the motion and (2) they don’t fall off the Earth. With the advancements
of science and technology, astronomers were able to understand how and why those
assumptions were false.

The Birth of Modern Astronomy

Your textbook discusses a number of great astronomers and their contributions to astron-
omy. Possibly the most significant advancement in early astronomy was when Galileo
Galilei constructed a telescope with 30-power magnification. With this new tool, the door
to understanding space was finally opened. Often, the need for advanced technology and
scientific research and development go hand-in-hand.

The Planets: An Overview

The solar system contains two groups of planets: the Jovian planets and the terrestrial
planets. The Jovians are referred to as the outer planets—Jupiter, Saturn, Uranus, and
Neptune. Think of it this way, they’re the large ones. The biggest terrestrial planet has a
diameter only one quarter as great as the diameter of the smallest Jovian.

The terrestrial planets are small in comparison and Earth-like in design. These are called
the inner planets. They include Mercury, Venus, Earth, and Mars.

Figure 15.17 and Figure 15.19 in your textbook portray these planets drawn to scale. A
quick glance at these figures will put this size difference into perspective.

Minor Members of the Solar System

This chapter provides a description of the planets and their moons found in our solar
system. It also discusses comets, meteors, meteorites, asteroids, and other unique
space objects.

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Lesson 6
 Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 6.1. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section, move on to Section 6.2.

Self-Check 6.1
Respond to the following based on your reading.

1. Why did early astronomers support a geocentric model of the solar system?

2. Explain retrograde motion. How does it apply to planets?

3. Of all the early astronomers, Galileo might have advanced the science of astron-
omy the most. What were his contributions?

4. What does an astronomical unit (AU) measure?

5. Explain the nebular hypothesis.

6. How do the Jovian and terrestrial planets differ?

7. The surface of the Moon shows numerous crater impact sites. Why are sites not
found on Earth?

8. What’s a lunar regolith?

9. Of what is Saturn’s ring system composed?

10. Describe a comet.

Check your answers with those in the back of this study guide.

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Lesson 6
SECTION 6.2: BEYOND OUR
SOLAR SYSTEM
Read the following section. Then read Chapter 16 in your textbook.

When you complete this section, you’ll be able to list the elements that make up
the universe.

Stellar Evolution
This chapter starts by looking at stars and the stages of star development. Each of the
five stages are ruled by gravity. The five stages include:
1. Stellar birth
2. Protostar stage
3. Main sequence stage
4. Red giant stage
5. Burnout and death

Since the gravitational field of a star is dependent on its mass, low, medium, and high-
mass stars exhaust a bit differently. Figure 16.5 in your textbook depicts stellar evolution
for a star about as massive as the Sun.

Properties of Stars
Stars have a number of different properties. A star’s color, for instance, is directly related
to its temperature. The hottest stars are blue. Mid-temperature stars, like ours, appear
yellow. The coolest are the red stars. The Hertzsprung-Russell (H-R) diagram is shown in
your textbook in Figure 16.4. The H-R diagram plots stars according to temperature and
absolute magnitude.

Apparent Brightness, Apparent Magnitude,

and Absolute Magnitude
Three things control the apparent brightness of a star as you would see it in the night
sky: how big it is, how hot it is, and how far away it is. For example, Star A might appear
brighter than Star B at first glance. This is the star’s apparent magnitude, meaning how it
appears from Earth with the unaided eye.

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Lesson 6
However, Star A might be many times closer than Star B. If these two stars were actually
the same distance from you, Star B would be several times brighter. This is the absolute
magnitude, or the “true” brightness of a star.

White Dwarfs and Black Holes

This chapter also describes other stars that don’t fit into the typical main-sequence stars
of the H-R diagram. A white dwarf star, for example, might be the size of Earth or even
smaller. Their densities are incredible. A spoonful of matter from a white dwarf would
weigh several tons. Then there are the black holes. A black hole is, well, a hole at whose
center is a collapsed star with a gravitational field so great that even light can’t escape.

Galaxies
Galaxies are simply clusters of stars. The Milky Way Galaxy, our galaxy, may have as
many as 100 billion stars within it. And how many galaxies are there in space? Some
astronomers estimate there are hundreds of billions.

Once you’ve finished studying this section, complete your discussion board assign-
ment as well as Self-Check 6.2. Answers to the self-check are at the end of this
study guide.
For additional practice with this material, complete the Give It Some Thought exer-
cises at the end of the chapter. Answers for these exercises are located on your
student portal. This additional practice is to check your mastery of the material. Do
not submit these to the school.
When you’re sure you understand the material in this section and all the previous
sections, you’ll be able to complete your final graded project.

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Lesson 6
 Self-Check 6.2
Respond to the following based on your reading.

1. Explain stellar parallax.

2. What’s a light-year? How far is it in kilometers?

3. What three factors control the apparent brightness of a star?

4. Describe a binary star.

5. What’s a supernova?

6. Why does the H-R diagram use a star’s absolute magnitude rather than its appar-
ent magnitude?

7. In the main-sequence stars on the H-R diagram, what color are the hottest stars?
Medium temperature stars? Coolest stars?

8. What are white dwarf stars?

9. What’s a galaxy? List the three types of galaxies.

10. Explain the big bang theory.

Check your answers with those in the back of this study guide.

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Lesson 6
EARTH SCIENCE
GRADED PROJECT
PART 1
Answer each of the following questions in 1 to 3 paragraphs. Each answer is worth five
points. Be sure to answer these questions in your own words.
1. Describe the components of the geocentric view of the universe that was held by
the early Greeks. How did Ptolemy account for the motions of the celestial bodies
in his model?
2. List and describe two of the minor members of the solar system.
3. The change from ancient to modern astronomy wasn’t easy. It required con-
siderable work and commitment by five key scientists. List and describe the
contributions made to modern astronomy by Nicolaus Copernicus, Tycho Brahe,
Johannes Kepler, Galileo Galilei, and Sir Isaac Newton.
4. Explain what criteria determine whether a planet is considered either Jovian or
terrestrial. Identify the Jovian and terrestrial planets. Briefly describe each planet,
incorporating the peculiarities of each.
5. Describe stellar parallax and explain how one would mathematically measure and
calculate the distance to a star using this method.
6. Discuss Earth’s moon. Elaborate on the following: maria, craters, regolith, high-
lands, and theories on the moon’s origin.
7. Describe the major types of galaxies and provide examples of each.
8. List and explain the stages of the life cycle of a star.
9. Describe the arrangement and properties of main sequence stars, including tem-
perature, size, and color, on the Hertzsprung-Russell diagram. Describe white
dwarfs and red giants.
10. Discuss the big bang theory and the evidence that supports it. Explain how some
scientists regard it as an adequate explanation of the origin of the universe.

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Graded Project
PART 2
For Part 2 of your graded project, select your own topic by choosing an article related to
Earth Science from the Discover Magazine website.

Note: Be sure to provide citation of the website you chose, including the title and
author of the article.

Once you’ve selected your article, write a three-to-five-page response paper, in which
you:
1. Explain how the article relates to your Earth Science course.
2. Answer the questions below, including your reflections on scientific inquiry and
methods.
3. Support your statements and reasoning with information and examples from the
article and your textbook.

Note: Short-answer format will not be accepted.

Questions
Before reading, ask yourself these questions:
1. What does the article appear to be about?
2. Why might this be an important topic?

During reading, ask yourself these questions:

3. What’s the aim of the article? In other words, why was the article written?
4. Pick one quotation from the article. Can you explain what the speaker means?
5. How has the scientific community’s understanding of the article’s topic changed
over time?
6. How does the article illustrate the importance of its topic?
7. How might science teachers be able to use the article to actively engage their
students in learning about the chosen topic? Consider hands-on activities that will
convey the importance of the topic.

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Graded Project
After reading, ask yourself these questions:
8. Why do scientists often study just one particular problem at a time? (Consider the
scientific method here.)
9. How could the information presented in the article benefit people and society? Why
should the human population care about the information presented in the article?
10. Computers often play an important role in scientific research. How are computers
utilized in this particular field of study? In using computers to analyze the article’s
topic, what problems do scientists face?

SUBMISSION GUIDELINES
Your project should be double-spaced, Times New Roman, and 12 point font. Use a stan-
dard document format with 1-inch margins.

Be sure to also include the following information at the top of your paper:
n Title of project (Earth Science Graded project)
n Your name
n Your student ID number
n Course title and number (SCI110 Earth Science)
n Graded project number (35063300)

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Graded Project
 GRADING CRITERIA
The following rubric will be used to grade your project:

The student
• Provides a clear discussion of the
assigned topic or issue
• Addresses the subject in complete
sentences, not just simple yes-or-no
statements
Content
• Supports his or her opinion by citing spe-
90 percent
cific information from the article chosen
• Stays focused on the assigned issues
• Writes in his or her own words and
uses quotation marks to indicate direct
quotations
• Properly cites the article he or she chose

The student
• Includes an introductory paragraph, a
body, and a concluding paragraph
• Uses correct grammar, spelling, punctua-
Written Communication
tion, and sentence structure
5 percent
• Provides clear organization by using suit-
able transitioning words
• Makes sure the paper contains no typo-
graphical errors

The project
• is double-spaced and in Times New
Roman, 12-point font
Format • Includes all the necessary identifying
5 percent information, such as the title of the proj-
ect, the student’s name and ID number,
the course number and title, and the
graded project number

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Graded Project
SUBMITTING YOUR PROJECT
Each project is individually graded by your instructor and therefore takes up to a few
weeks to grade.

Be sure that each of your three files contains the following information:
n Your name
n Your student ID number
n The lesson number (350633)
n Your email address

To submit your graded project, follow these steps:

1. Go to http://www.pennfoster.edu.
2. Log in to your student portal.
3. Click on Take Exam next to the lesson you’re working on.
4. Follow the instructions provided to complete your exam.

Be sure to keep a backup copy of any files you submit to the school!

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Graded Project
SELF-CHECK ANSWERS
Self-Check 1.1
1. Minerals (1) are naturally occurring, (2) are solid, (3) have orderly crystalline
structures, (4) have unique chemical compositions, and (5) are inorganic.
2. Protons are found in the nucleus of an atom and have a positive electrical charge.
Neutrons also are found in the nucleus but have a neutral electrical charge.
Electrons are found in the orbiting shells and have a negative electrical charge.
3. An atom is the smallest particle of an element. Atoms are electrically balanced,
having the same number of positive protons and negative electrons. An ion is an
atom with an imbalance (differing number) of protons and electrons. Therefore, an
ion has either a positive or negative charge. Isotopes are atoms of the same ele-
ment, only with differing numbers of neutrons.
4. The number of electrons is equal to the number of protons in a neutral atom. Using
this information, the atomic number is 17, because there are 17 protons in this
atom. The number of neutrons in an atom can be found by taking the mass number
and subtracting the atomic number from it. 35 – 17 = 18; 18 neutrons would be
found in this atom.
5. Radioactive decay is the disintegration of unstable isotopes of a particular element.
6. Properties of minerals include crystal form, luster, streak, color, hardness, cleav-
age, fracture, and specific gravity.
7. The crystalline structure of any mineral is unique and different from that of any
other mineral. It’s the external expression of a mineral’s internal arrangement of
atoms.
8. Although most minerals are thought to be a particular color, like gold and silver,
slight impurities can sometimes alter this “expected” color. Quartz, for example,
can be pink, purple, milky white, and even black based on the impurities present.
9. Silicate minerals contain specific building blocks of silicon-oxygen tetrahedrons.
Nonsilicates lack silicas in their mineral structures.
10. Mineral resources are Earth’s useful minerals that can be recovered for use.
Mineral reserves include known deposits of minerals that can be mined for a profit.

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Self-Check Answers
 Self-Check 1.2
1. Igneous rock forms from cooling lava. This rock is then acted upon by weathering
and erosion. This produces sediment that, over time, builds layers on the bottom of
the ocean that converts into sedimentary rock. When sedimentary rock or igneous
rock is forced deep enough, it undergoes intensive heat and pressure and is con-
verted into metamorphic rock. Eventually, this may be melted, forming magma that
can be brought back to the surface to form igneous rock.
2. Magma is molten rock within the Earth. Lava is molten rock that has been forced
onto the Earth’s surface.
3. The three main kinds of rock found in Earth’s crust are igneous, sedimentary, and
metamorphic.
4. Extrusive igneous rock forms when molten rock erupts and solidifies on the Earth’s
surface. Intrusive igneous rock forms when the molten rock solidifies within the
crust.
5. N. L. Bowen developed a system for determining the type of crystalline structure
within a mineral based on the rate of the cooling lava or magma that formed it.
6. Water and temperature are the two parts of frost wedging. First, liquid water flows
into a crack in a rock. Second, the temperature drops below freezing, converting
the liquid water to ice. When water freezes, it expands by 9 percent. This expan-
sion causes the ice to break the rock even more. The more the water goes back
and forth between a solid and a liquid, the more it breaks apart the rock. Chemical
weathering alters the internal structure of minerals, whereas mechanical weather-
ing doesn’t.
7. Sediment is simply unconsolidated rock particles. It forms through the processes of
weathering that are continually attacking any and all exposed rock.
8. Lignite and bituminous coals form like any other sedimentary rock, with layer after
layer building on top of one another. Anthracite coal, however, results when lignite
or bituminous coal comes into contact with intense heat and pressure within the
crust. Hence, it’s formed by metamorphic properties.
9. Fossils form only in sedimentary rock. The remains of once-living organisms are
trapped between the building sediments. Igneous and metamorphic rocks are
formed by intense heat that would destroy any organic remains.
10. Foliated metamorphic rock has a layered texture. Nonfoliated metamorphic rock
doesn’t have a layered texture.

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Self-Check Answers
 Self-Check 2.1
1. Oceans hold 97 percent, ice sheets and glaciers hold a little more than 2 per-
cent, and less than 1 percent is held in streams, lakes, subsurface water, and the
atmosphere.
2. Water falls from the sky in the form of precipitation (mostly rain). This water runs off
into lakes, rivers, or eventually the ocean, where it evaporates back into the atmo-
sphere. Eventually, it returns in the form of precipitation.
3. Velocity is the distance that water travels in a unit of time. A stream’s velocity is
determined by its gradient (slope), channel characteristics (for example, wide, shal-
low, deep, narrow, bumpy, or smooth), and its discharge (the amount or volume of
water in the stream itself).
4. The capacity of a stream is the greatest amount or maximum load of solid particles
it can carry. The greater the volume of water, the greater the stream’s capacity.
5. The ultimate base level of a stream is sea level. This is the lowest level to which
stream erosion could lower the land.
6. As a stream or river enters a lake or ocean, it spreads out over a large area. This
causes it to decrease in velocity. As such, it drops its load, forming mud, sand, or
other debris, forming flats at the mouth of the river.
7. A Yazoo tributary is a stream that, due to a dike, levee, or other blockage, can’t
reach its intended river destination. As such, it will flow along the outside of the
blockage until it can find a way through.
8. An aquifer is an area of underground rock that permits water to easily permeate it.
9. Both hot springs and geysers are heated by underground heat sources within the
crust. The heating of water forces it to expand and move upward, back toward the
surface.
10. In normal aquifers, the water height is at the water table. In an artesian aquifer,
groundwater rises above the level where it was initially encountered. This occurs
because gravity is pulling water into one end of the aquifer, causing the present
water in the aquifer to become pressurized.

Self-Check 2.2
1. Glaciers form on land when the amount of snow in the winter is greater than the
amount that melts during the summer.
2. Alpine glaciers develop on mountaintops. There, the air is colder and damper than
adjacent lowlands. Winter snows are deep, and summers are short and cool. Their
growth depends on both temperature and the amount of precipitation.

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Self-Check Answers
 3. In cold, wet environments, only a portion of the winter snow melts during the short
summer. If snow lasts through the summer, it converts to rounded grains of ice. If,
over time, these ice grains are buried deeper and deeper under snow pack, they’ll
be converted to glacial ice. Glacial ice is simply closely packed ice crystals.
4. Moraines are layers or ridges of till (glacial deposition). Lateral and medial
moraines are common only to mountain valleys. End and ground moraines are
associated with areas affected by ice sheets or valley glaciers.
5. An ice age is a period when alpine glaciers descend into lowland valleys and conti-
nental glaciers spread over land in high latitudes. Glaciers several kilometers thick
spread across the landscape. Due to the great weight of the ice, the continents
sink deeper into the asthenosphere. In addition, the ice weathers rock and erodes
soil, altering the landscape.
6. Wind erosion in the desert environment can pick up, transport, and deposit large
quantities of fine sediment. Features at or near the ground can experience con-
siderable sandblasting as a result. For example, telephone poles along desert
highways need metal collars a meter or so high so they aren’t “cut off” by this sand-
blasting effect.
7. The water table is very deep, and the surface soils are dry and porous. Water flow-
ing shortly after a rainfall will usually infiltrate into the ground before it goes very
far.
8. An alluvial fan is a fan-shaped deposit of sediment formed where an intermittent
stream washed onto the desert. A flat, dry lake bed is called a playa. Once filled, it
becomes a short-lived playa lake that may last only for days or weeks.
9. Desert pavement is formed when wind erodes silt and sand from desert areas and
leaves behind pebbles and cobbles. This phenomenon prevents winds from erod-
ing additional sand and silt, even though this finer sediment may be beneath the
layer of stones. The surface then becomes like pavement.
10. A dune is a mound of sand that has been deposited by the wind. The wind erodes
the sand from the surface of the desert and deposits it in a depression or where the
wind slows down. This accumulating sand results in a dune.

Self-Check 3.1
1. The Mesosaurus was a fish-eating reptile that existed 260 million years ago. Its
fossils have been found in both South America and Africa. It’s highly unlikely that
the same species would exist on two different continents separated by thousands
of miles of water. In 1915, Alfred Wegener, a German meteorologist and geophys-
icist, suggested that 260 million years ago these two continents weren’t separated
by a large ocean, but instead were part of one giant land mass. Modern evidence
confirms that Wegener was right.

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Self-Check Answers
 2. The key difference between the lithosphere and the asthenosphere is in their com-
position. The lithosphere is made of hard, strong rock and is relatively cool. Rock in
the asthenosphere is weak and plastic. The reason for this difference is the rising
temperatures in the asthenosphere.
3. The major tectonic plates are the African, Eurasian, Indian-Australian, Antarctic,
Pacific, North American, and South American plates.
4. The asthenosphere is soft and weak. One to two percent of it is molten rock.
Therefore, the lithosphere can float, or slide, on the soft plastic rock of the
asthenosphere.
5. A divergent boundary is a fracture between two plates where the plates are moving
away from each other. A convergent boundary is one where the plates are moving
toward each other. A transform fault boundary is one where the plates are sliding
horizontally past each other.
6. A subduction zone is a long, narrow zone where one lithospheric plate descends
beneath another.
7. The crust is a thin, cool layer made of hard, strong rock. The mantle is roughly
2,900 kilometers thick. The composition of the mantle is similar to that of the crust,
but because of the much higher temperatures farther into the Earth, the mantle is
weak and plastic.
8. The layer cake model consists of two convection layers—a thin dynamic layer in
the upper mantle and a thicker, sluggish one located below. In the whole-mantle
convection model, it’s proposed that whole-mantle convection occurs and stirs the
entire 2,900 km thick mantle.

Self-Check 3.2
1. An earthquake is the vibration of Earth produced by a rapid release of energy.
2. The focus is the initial stress-release point, the location where an abrupt movement
creates an earthquake. The point on the Earth’s surface directly above the focus is
referred to as the epicenter.
3. Earthquakes occur more often along or near faults, or the boundaries of tectonic
plates. These areas produce the most stress on crustal rock.
4. Seismology is the study of earthquake waves. Seismographs are instruments
that record earthquake waves. A seismogram is the actual recorded data of an
earthquake.
5. Earthquakes produce two types of seismic waves: surface waves and body waves.
Surface waves travel around the outer layer of the Earth. Body waves travel
through Earth’s interior.
6. An anticline is a fold of sedimentary strata that resembles an arch. A syncline is a
linear downfold in sedimentary strata—the opposite of an anticline.

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 7. Orogenesis is the process of mountain building.
8. The volcanic island arc is sliced off the subducting plate and thrust onto the conti-
nent, and a new subduction zone forms seaward of the old subduction zone. The
accretion of the microcontinent to the continental margin shoves the remnant island
arc further inland and grows the continental margin seaward.

Self-Check 3.3
1. The gases released by an eruption are about 70 percent water vapor, 15 percent
carbon dioxide, 5 percent nitrogen, 5 percent sulfur and lesser amounts of chlorine,
hydrogen, and argon.
2. The three major types of volcanoes are shield volcanoes, cinder cones, and com-
posite cones. Shield volcanoes are broad, slightly domed, and consist mainly of
basaltic lava. Cinder cones are built from ejected lava fragments and frequently
occur in groups. Composite cones or stratovolcanoes are large and the most vio-
lent type of volcanos.
3. A composite cone volcano is composed of both lava flows and pyroclastic
materials.
4. Pyroclastic materials are ejected during an eruption. These ejected fragments
range in size from fine dust particles and volcanic ash to pieces that weigh several
tons.
5. A caldera is a large collapsed depression. The three most common methods of
formation are (1) the collapse of the summit of a large composite volcano, (2) the
collapse of the top of a shield volcano caused by subterranean drainage from the
central magma chamber, and (3) the collapse of a large area caused by the dis-
charge of large volumes of silica-rich pumice and ash.
6. A dike is a sheet-like intrusive rock that develops when magma oozes into a frac-
ture. A sill is a tabular pluton formed when magma is injected along sedimentary
bedding surfaces.
7. Most active volcanoes are located along the margins of the ocean basins. The
Ring of Fire is a set of many volcanoes along the circum-Pacific belt that mainly
consist of composite cones, which emit volatile-rich magma.
8. A hot spot is a concentration of heat within the mantle. As it rises in a plume, it
causes decompression melting of the crust, creating a hot spot in the center of a
plate. The Hawaiian Islands are a result of such a hot spot. Over 100 hot spots
have been identified. Many have existed for millions of years.

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 Self-Check 3.4
1. Catastrophism is the concept that Earth was shaped by catastrophic, short-term
events. Uniformitarianism is the concept that the processes that shaped Earth in
the geologic past are essentially the same as those operating today.
2. The physical, chemical, and biological laws that are acting upon our world today
are the same laws that have operated on our planet in the geologic past.
3. Geologic time is measured in two ways. Relative age refers only to the order in
which events occurred. Absolute age refers to the age in years.
4. The law of superposition simply states that in an undeformed sequence of sedi-
mentary rocks, each bed is older than the one above it and younger than the one
below it.
5. Conformable strata implies that the initial rock-forming layers were deposited
without interruption. Unconformable strata implies that the forming layers were
interrupted during rock development.
6. Index fossils are associated with a particular span of geologic time.
7. A stable isotope is one that doesn’t change with time. An unstable isotope is radio-
active, meaning that over time its nucleus spontaneously decays at a consistent
rate.
8. Half-life is the time it takes for half of the atoms in a radioactive sample to decay.
Because the half-life of a radioactive isotope is consistent, scientists can estimate
the ages of rocks, minerals, and fossils by measuring this rate of decay.
9. The three eras from oldest to present are Paleozoic (ancient life), Mesozoic (mid-
dle life), and Cenozoic (recent life).
10. The primary problem with placing numerical dates is the fact that not all rocks can
be dated by radiometric methods. One problem lies with the fact that in some rocks
not all of the present minerals have formed at roughly the same time. Also, some
sedimentary rocks contain radioactive isotopes that have weathered from other
rocks.

Self-Check 4.1
1. The Pacific Ocean is the largest ocean on Earth.
2. The obvious difference is that oceans are water and continents are land. However,
the key difference is that the volume of the ocean water is so large that all of
Earth’s continental lands could be placed inside the ocean basins with consider-
able room to spare.
3. Seawater is relatively difficult to make in the laboratory. It consists of about 3.5
percent salts. Seawater also contains chlorine, sulfate, magnesium, calcium,
potassium, strontium, bromine, carbon, and other elements.

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 4. The surface mixed zone accounts for roughly 2 percent of the total global ocean.
The surface mixed zone receives most, if not all, of the solar radiation, making it
the warmest layer. Also, fast-moving surface currents, waves, and tidal action keep
this zone well mixed throughout its entire depth.
5. The transition zone accounts for roughly 18 percent of the global ocean. Two noted
features of this zone are a sharp drop in temperature referred to as the thermocline
and a rapid decrease in salinity referred to as the halocline.
6. The deep ocean makes up about 80 percent of the global ocean. The temperature
of the deep ocean is very cold. No light penetrates into the deep ocean; therefore,
it’s pitch black. Salinity levels are relatively low compared to the other two zones.
7. Bathymetry is the science of sending sound waves to the ocean floor and recording
their echoes. This allows scientists to measure the topography of the seafloor.
8. Deep, steep-sided valleys that are cut into the continental slope are called subma-
rine canyons. Turbidity currents may actually create submarine canyons. These
currents consists of dense, sediment-laden water that flows across the continental
shelf and down over the continental slope. If they remain in the same location long
enough, they’ll erode submarine canyons into the slope.
9. Seamounts are isolated volcanic peaks. If a seamount protrudes above the sur-
face, it will become an island. However, over time exposed seamounts weather
until they’re either at or below sea level. These flat-topped seamounts are referred
to as guyots.
10. The three types of seafloor sediment are terrigenous (sediment washed in from
nearby continents), biogenous (sediment consisting mainly of shells and skeletons
of tiny sea creatures), and hydrogenous (sediment made mainly of minerals crys-
tallized from water).

Self-Check 4.2
1. Large surface currents develop from friction between the ocean and the wind blow-
ing across the surface. The Coriolis effect deflects these currents to the right in the
Northern Hemisphere and to the left in the Southern Hemisphere.
2. An upwelling is the rising of cold water from the deep zone that replaces the
warmer waters of the surface mixed zone. Upwelling sites are usually located on
the outside edge of a large surface current where it makes an abrupt turn.
3. Deep ocean currents are also called thermohaline circulation. At high latitudes,
such as the Arctic Ocean, large areas of sea ice form in early autumn. Sea ice
doesn’t contain salt. The salt is left behind, causing the surrounding seawater to
become saltier, or denser. As the sea water becomes denser and colder, it sinks.
This creates a vertical current until it strikes the bottom; then it follows the contours
of the ocean floors, forming deep ocean currents. The exact same scenario occurs
in the Antarctic region six months later.

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 4. Waves in the deep ocean might appear to be relatively small. This is due to the
depth of area for the traveling wave energy. As the wave energy approaches shal-
lower water, the room for the energy decreases. This forces the wave energy to
push upward as the water becomes shallower, building the wave as it approaches
the shore.
5. It simply means that no shoreline is stable. All coastlines are either emerging or
submerging. They’re basically evolving with their surrounding environment.
6. Groins are short walls built at a right angle to the shore to trap moving sand and to
protect existing beaches.
7. An emergent coastline forms when a portion of a continent that was previously
under water becomes exposed as dry land. Falling sea levels or rising land
can cause emergence. A submergent coastline develops when the sea floods.
Submergence occurs when the sea level is rising or the coastline land sinks.
8. The Moon has a stronger gravitational pull on Earth than the Sun does simply
because it’s considerably closer. The Moon is roughly 240,000 miles away from
Earth, whereas the sun is about 93,000,000 miles away.
9. Spring tides have a greater variation between their high and low cycles than neap
tides do. During spring tides, the Sun and Moon are directly in line with Earth and
their gravitational fields combine to create very strong tides. During neap tides,
the Moon is 90 degrees (right angle) out of alignment with the Sun and Earth.
Therefore, each offsets the effect of the other. The differences between the high
and low tides are much smaller with neap tides.
10. A tidal delta is a feature created when a rapidly moving tidal current emerges
through a narrow inlet and slows. The slowing effect causes a sediment to be
deposited.

Self-Check 5.1
1. Weather is the condition of the atmosphere at any particular place and time.
Climate is the accumulation of weather events over long periods of time.
2. The four layers are the troposphere, stratosphere, mesosphere, and thermosphere.
The temperature of the atmosphere changes with altitude. The troposphere is
warmest near the surface, but begins to cool near its upper limit. In the strato-
sphere, the temperature remains constant until near the stratopause, where the
temperature increases. Once in the mesosphere, the temperature declines. It bot-
toms out near the top of the mesosphere and remains fairly constant throughout
the thermosphere.
3. The lower atmosphere, or the area closest to Earth, has a mix of gases called air.
The air that you live in is composed of 78 percent nitrogen and 21 percent oxygen.
The remaining 1 percent is a combination of water vapor, carbon dioxide, methane,
argon, and dust.

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 4. Rotation is the spinning of the Earth on its axis. Earth has one rotation every 24
hours. Revolution is Earth’s orbit around the sun. One revolution is 365 days. Day
and night are the result of the Earth’s rotation on its axis. The seasons are caused
by Earth’s changing orientation to the Sun; while the Earth’s axis is inclined at 23½
degrees, it’s not always in the same direction.
5. Conduction is the transfer of heat through matter by molecular activity. Convection
is the transfer of heat by the movement of a mass or substance. Convection takes
place only in fluids.
6. Approximately 50 percent of the sunlight is scattered, reflected, or absorbed by the
atmosphere and clouds. Of the 50 percent that reaches Earth’s surface, 47 percent
is absorbed by Earth and the remaining three percent is reflected.
7. Sunlight enters the atmosphere and heats the Earth’s surface. This heat then
radiates upward into the air. Most will radiate into space, but some heat will be
absorbed by carbon dioxide, water vapor, and other greenhouse gases. This warm-
ing of the atmosphere from the bottom up is a natural phenomenon that keeps
Earth’s global temperatures within the range needed to support life.
8. Global warming is a buildup of excessive greenhouse gases (mostly carbon diox-
ide) that results in too much heat being trapped in the atmosphere. A warmer
atmosphere could result in higher sea levels due to melting ice caps and stronger
atmospheric storms.
9. Temperature changes occur for a number of reasons. When climbing a mountain, it
can be hot at the bottom but cold at the top. The tropics are hotter than the higher
latitudes because they receive more sunlight. Cloud cover reflects more sunlight,
whereas no cloud cover increases the amount that reaches the ground. Albedo
refers to an object’s reflectivity.
10. Global temperature patterns decrease poleward from tropics and result in a latitu-
dinal shift with seasons. Also, warmest and coldest temperatures are over land. In
the Southern Hemisphere, isotherms are straighter and more stable.

Self-Check 5.2
1. Sublimation—solid to gas; melting—solid to liquid; freezing—liquid to solid; con-
densation—gas to liquid; deposition—gas to solid; evaporation—liquid to gas
2. Sublimation means to go from a solid to a gas, without going through a liquid state.
Deposition means to go from a gas directly to a solid, also bypassing the liquid
state.
3. Relative humidity is the amount of water vapor in an air mass relative to the maxi-
mum it can hold at a given temperature.

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 4. The dew point is the temperature at which the relative humidity of air reaches 100
percent and the air becomes saturated. When the air is warm and humid, as on a
typical summer evening, grass, cars, and other objects lose heat after the sun sets.
These objects become colder through radiation. During the night, water vapor con-
denses on the cool objects. This water is called dew.
5. Adiabatic temperature change refers to vertical temperature changes in the atmo-
sphere. As you move upward in the atmosphere the temperature decreases. This
is referred to as adiabatic cooling. If you’re high in the atmosphere and descend,
moving downward, the temperature will increase. This is referred to as adiabatic
heating.
6. The four processes that lift air are orographic lifting, frontal wedging, convergence,
and localized convective lifting. In orographic lifting, elevated terrains act as bar-
riers. In frontal wedging, cool air acts as a barrier to warm air and fronts form.
Convergence occurs when air flows together and rises. Localized convective lifting
occurs when pockets of air are warmed more than the surrounding air.
7. Unstable air is simply air that doesn’t resist vertical displacement.
8. Cirrus: Wispy clouds that look like hair or appear feathery as they move high
across the sky. Cumulus: Fluffy, white, globular clouds with flat bottoms and billowy
tops. Stratus: Sheet-like clouds, usually low, that sometimes cover the entire sky
like a veil.
9. Fog is the formation of a cloud at or near the Earth’s surface.
10. Clouds are composed of extremely small droplets of water about 0.01 millimeters
in diameter. When the air temperature in a cloud is above freezing and conditions
are just right, these tiny droplets collide and coalesce, forming larger and larger
droplets. Eventually, if these droplets become large enough, they’ll fall as drizzle or
rain.

Self-Check 5.3
1. Air pressure is simply the pressure exerted by the weight of the air above. Average
air pressure at sea level is 1 kilogram per square centimeter, or 14.7 pounds per
square inch.
2. A barometer is an instrument that measures atmospheric pressure.
3. Isobars are lines drawn on a weather map connecting points of equal atmospheric
pressure. They show the distribution of atmospheric pressure differences.
4. Wind is the result of horizontal differences in air pressure. Air flows from areas of
high pressure to areas of low pressure.
5. Lows, or low pressure cyclones, are centers of low pressure. Highs, or high-pres-
sure anticyclones, are high-pressure centers.

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 6. Due to the intense solar radiation at the equator, the air is superheated and rises in
the atmosphere. This causes an area called an equatorial low all the way around
the globe. This air moves north and south of the equator until it reaches 20 to 30
degrees latitude. There, it sinks, causing a subtropical high. This subtropical high,
combined with the Coriolis effect, produces the trade winds. These wind currents
flow around the globe just north and south of the equator.
7. During a warm summer’s day, the land along the sea coast heats faster than the
nearby water. The air over the land also becomes heated and will then rise. This
creates a low-pressure zone. The air over the water is at a higher pressure, so
it flows onto the land, bringing cool sea breezes. In the evening and at night, the
opposite occurs. The land cools first, creating a high pressure zone. The air then
flows over the land and out to sea.
8. Mountain-valley breezes usually flow up or down mountain slopes. By late morn-
ing, the valley, or lowland around a mountain, heats up enough for thermals (rising
warm air currents) to begin moving upward following the contours of the mountain.
In the evening, the opposite occurs. The air flows down the slope into the valley or
lowlands.
9. Chinooks are winds that sometimes move down the east slopes of the Rockies.
They’re created when strong pressure gradients develop in the high mountains.
Santa Ana winds are hot, desiccating winds that occur in southern California. Such
winds can greatly increase the threat of wildfires in this extremely dry region of the
United States.
10. A wind vane is an instrument placed on the top of a building to determine the direc-
tion of the wind.

Self-Check 5.4
1. An air mass is a large area of air, typically 1,600 kilometers (1,000 miles) or more
across, that has similar temperature, moisture, and other characteristics through-
out. Air masses move around the globe from west to east.
2. Air masses are given names according to the area they developed over. For exam-
ple, a cP air mass means it developed over a continent (c) and in polar (P) regions.
Hence, it will be cold and dry. An mT air mass is a maritime tropical. This means it
developed over water (m) and in the tropics (T). An mT air mass will be warm and
wet.
3. Fronts are boundaries that separate different air masses, one warmer than the
other.
4. Middle-latitude cyclones are the major weather producers for most of the North
American continent. They’re large centers of low pressure that generally travel
from west to east.

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 5. An incoming cold front comes in faster and steeper than an advancing warm front;
therefore, it causes greater destabilization of air. This increases the likelihood for
violent weather.
6. A thunderstorm is produced by a cumulonimbus cloud. It’s always accompanied by
lightning and thunder. Thunderstorms are usually of short duration and commonly
have strong, gusty winds; rain; and, sometimes, hail.
7. First, moisture in rising air cools and condenses, forming a cumulus cloud. As the
water vapor condenses, it releases large amounts of heat energy. Large droplets or
ice crystals develop, but the rising air keeps them in suspension within the cloud.
Next, water droplets or hailstones become so heavy that updrafts can no longer
support them, and they fall as rain or hail. This rain or hail chills the lower part of
the cloud. This cooler air sinks, forming a down draft. Warm, moist air is no longer
drawn into the cloud, and it loses its energy source. Finally, the storm dissipates.
8. A tornado is a small, very intense rotating column of air with exceedingly high
winds. Tornados often are produced along cold fronts in conjunction with severe
thunderstorms.
9. The Enhanced Fujita intensity scale, or EF-scale, is a common guide for catego-
rizing the intensity of a tornado. The scale goes from EF-0, a tornado with winds
below 85 miles per hour, to EF-5, a tornado with wind speeds over 200 miles per
hour.
10. A hurricane is a massive cyclonic tropical storm with minimum sustained winds in
excess of 119 kilometers (74 miles) per hour.

Self-Check 6.1
1. Because people standing on Earth have no sensation of motion, Ptolemy, Aristotle,
and other early astronomers reasoned that the Earth was stationary. And so, they
reasoned that everything in the heavens must be revolving around us. Hence,
Earth must be the center of the universe.
2. Retrograde motion is similar to a jogger passing someone who’s walking in the
same direction. Even though they’re both moving in the same direction, when the
jogger glances back at the walker, the walker seems to be going in the opposite
direction. In regards to planets, for most of the year, they appear to drift eastward
with respect to the stars. Then they’ll seem to reverse their direction and drift west-
ward, much like the jogger and walker.
3. Galileo Galilei made numerous contributions to science, and to astronomy, in par-
ticular. He supported a Sun-centered universe and made his own telescope with a
30-power magnification. This enabled him to make many new observations of the
Sun, Moon, and planets that no one had ever witnessed before.
4. Astronomical unit (AU) refers to the average distance from Earth to the Sun—150
million kilometers, or 93 million miles.

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 5. The nebular hypothesis proposes that all the bodies of the solar system formed
from an enormous nebular dust cloud. This nebular cloud consisted mostly of
hydrogen and helium, with small amounts of silicon, aluminum, iron, calcium, oxy-
gen, carbon, nitrogen, and other elements.
6. Terrestrial planets are small, Earth-like bodies. The four terrestrial planets are
the inner planets—Mercury, Venus, Earth, and Mars. These planets are dense,
consisting mostly of rocky and metallic materials with small amounts of ice and
gas. Jovian planets are very large, Jupiter-like bodies. The Jovian planets are
Jupiter, Saturn, Uranus, and Neptune. They’re considered the outer planets. Even
though Jovians are much larger than the terrestrial planets, they’re not nearly as
dense. Saturn, for example, has a density of only 0.7 that of water, which means
this planet could actually float on an ocean if you could find one big enough. The
Jovians contain large amounts of gases and ices.
7. The main reason crater impact sites show up over the entire surface of the Moon
but not on Earth is because of running water. If a meteorite struck the Moon five
million years ago, it would look virtually the same today as it did shortly after
impact. On Earth, the processes of weathering and erosion would have removed
most of the evidence that such a strike ever took place.
8. Lunar regolith is a soil-like layer composed of igneous rocks, glass beads, and fine
particles called lunar dust.
9. The rings of Saturn are composed of individual particles called “moonlets” of ice
and rock, which circle the planet and regularly impact one another.
10. Comets are referred to as “dirty snowballs” because they’re made of frozen gases
that hold together small pieces of rocky material. Short-period comets complete
one orbit around the Sun every 200 years or less. Some comets may actually take
hundreds of thousands of years to complete a single orbit.

Self-Check 6.2
1. Stellar parallax is the very slight back-and-forth shifting in the apparent position of
a nearby star due to the orbital motion of our planet—Earth.
2. A light-year is the distance light travels in one year—about 9.5 trillion kilometers, or
5.8 trillion miles.
3. The three factors that control the apparent brightness of a star as seen from Earth
are how big it is, how hot it is, and how far away it is.
4. The term binary means two. Binary stars are a pair of stars orbiting each other.
Imagine seeing two suns rise every morning. They have a common center of mass
that allows them to orbit one another. If you look at the second star in the handle
of the Big Dipper with a light-powered telescope or even a good pair of binoculars,
you may be able to see that this star is actually two binary stars.

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 5. A supernova is thought to be triggered when a massive star consumes most of its
nuclear fuel. Without its energy source to maintain its immense gravitational field,
it collapses. The forthcoming implosion is of cataclysmic proportion, resulting in
a shock wave that moves outward from the star’s center. This outward blast of
energy is the actual supernova.
6. The absolute magnitude takes into consideration a star’s distance from us. One
star could appear much brighter than a second star only because it’s closer. In
reality, the second star could be much larger and hotter and burn much brighter,
but because it’s much farther away it doesn’t appear to be as bright. Absolute mag-
nitude basically calculates a star’s brightness assuming that all stars are an equal
distance from Earth.
7. In the H-R diagram, the hottest stars are blue (30,000 K), the medium stars are yel-
low (5,000 to 6,000 K), and the coolest stars are red (less than 3,000 K).
8. White dwarf stars are much fainter than main-sequence stars. They’re also much
smaller. Some are only the size of Earth or smaller.
9. A galaxy is a massive cluster of stars. Some galaxies, such as our own Milky Way
galaxy, may have as many as 100 billion stars within them. The three types of gal-
axies are spiral, elliptical, and irregular.
10. According to the big bang theory, the entire universe was at one time confined to
a dense, hot, massive ball. Then, about 14 billion years ago, it exploded, hurling
material in all directions. This marks the beginning of the universe. All matter and
space were created at that instant. Galaxies, stars, moons, planets, comets, and
everything else have developed from the cooling, condensing dust and gas clouds
of that initial explosion.

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