Chapter 1—The Science of Historical Geology
CHAPTER 1—THE SCIENCE OF HISTORICAL GEOLOGY
CHAPTER OVERVIEW
This chapter provides an introduction to the science of geology from both physical and historical
perspectives. Physical geology examines the structure, composition, and processes that affect the Earth
today. Historical geology considers all the past events on Earth. This chapter discusses the scientific
method and shows how it can be used to establish a scientific theory. The three prevailing themes in the
history of the Earth are also discussed: the immensity of geologic time, plate tectonics, and organic
evolution.
LEARNING OBJECTIVES
By reading and completing information within this chapter, you should gain an understanding of the
following concepts:
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Describe and implement the scientific method to solve problems.
Discuss the concept of deep geologic time and the use of radioactive dating to determine
the absolute age of rock specimens.
Discuss plate tectonics and define divergent plate boundaries, convergent plate
boundaries, and transform plate boundaries.
Discuss the general concept of evolution and differentiate organic evolution from physical
evolution.
Apply the concept of natural selection to organic evolution.
CHAPTER OUTLINE
I.
Why Study Earth History
II.
Geology Lives in the Present and the Past
III.
A Way to Solve Problems: the Scientific Method
IV.
Three Great Themes in Earth History
A. Deep Time
B. Plate Tectonics
C. Evolution of Life
V.
What Lies Ahead
Chapter 1—The Science of Historical Geology
KEY TERMS
(Pages 1–9)
absolute age (7): The geologic age of a fossil, or a geologic event or structure expressed in units of
time, usually years.
asthenosphere (7): The zone between 50 and 250 kilometers below the surface of the Earth, where
shock waves of earthquakes travel at much reduced speeds, perhaps because of less rigidity. The
asthenosphere may be a zone where convective flow of material occurs.
convergent boundary (7): Develop when two plates move toward one another and collide.
Characterized by a high frequency of earthquakes and are thought to be the zones along which folded
mountain ranges or deep-sea trenches may develop.
crust (7): The outer part of the lithosphere; it averages about 32 kilometers in thickness. Seismically
defined as all of the solid Earth above the Mohorovicic discontinuity. The thin, rocky veneer that
constitutes the continents and the floors of the oceans.
divergent boundary (7): Develop when two plates move way from each other. May manifest themselves
as mid-oceanic ridges complete with tensional (pull-apart) geologic structures. The rending of the crust is
accompanied by earthquakes and enormous outpourings of volcanic materials that are piled high to
produce the ridges itself.
half-life (7): The time needed for half of the original quantity of radioactive atoms to decay to daughter
products.
historical geology (2): A branch of geology concerned with the systematic study of bedded rocks and
their relations in time and the study of fossils and their locations in a sequence of bedded rocks.
hypothesis (4): An explanation for an observation. It is subject to testing and modification. If well
supported by evidence, it then may become a theory.
lithosphere (7): The outer shell of the Earth, lying above the asthenosphere and comprising the crust
and upper mantle.
mantle (7): A thick, homogeneous layer surrounding the core composed of several concentric layers.
Believed to have stony, rather than metallic, composition. Oxygen and silicon probably predominate and
are accompanied by iron and magnesium as the most abundant metallic ions. Probably composed of
peridotite, an iron- and magnesium-rich rock.
natural selection (8): The natural process where by organisms are preserved or eliminated according to
their fitness or adaptation to their environment.
physical geology (2): That branch of geology concerned with understanding the composition of the
Earth and the physical changes occurring in it, based on the study of rocks, minerals, and sediments,
their structures and formations, and their processes of origin and alteration.
plate tectonics (7): The theory that explains the tectonic behavior of the crust of the Earth in terms of
several moving plates that are formed by volcanic activity at oceanic ridges and destroyed along great
ocean trenches.
relative age (7): The placing of an event in a time sequence without regard to the absolute age in years.
scientific law (4): If a theory continues to triumph over every challenge, it can be raised to the level of a
scientific law.
scientific method (4): A systematic way to find answers to questions, solutions to problems, and
evidence to prove or disprove ideas and beliefs.
Chapter 1—The Science of Historical Geology
theory (4): A hypothesis that survives repeated challenges and is supported by accumulating favorable
evidence.
transform boundary (7): A plate boundary along which plates slide past one another, and the crust is
neither produced or destroyed. On land it is recognized as a strike-slip fault.
Chapter 1—The Science of Historical Geology
MULTIPLE-CHOICE QUESTIONS
1.
The Earth’s age is approximately
a. 300,000 years.
b. 4,600,000 years.
c. 4,600,000,000 years.
d. 5,500,000,000 years.
2.
To discover how the Earth was formed, geologists identify the minerals in
a. meteorites.
c. rock strata in various locations on Earth.
b. lunar samples.
d. rocks extruded in volcanic eruptions.
3.
The species of primates that evolved on the Earth between 300,000 and 150,000 years ago is
a. homo erectus.
c. Cro-Maguous.
b. Neanderthals.
d. homo sapien.
4.
The study of the Earth’s origin and evolution, changes in the distribution of lands and seas, the
growth and reduction of mountains, and the succession of animals and plants is called
a. Earth science.
c. historical geology.
b. physical geology.
d. geological science.
5.
To a scientist, knowledge that has a very high probability of being correct is called
a. data.
c. hypothesis.
b. theory.
d. law.
6.
Humans have penetrated and explored the deep interior of Antarctica for only the last ___________
years.
a. 100
c. 10,000
b. 1,000
d. 100,000
7.
The study of the Earth’s materials (rocks and minerals) and the varied processes that occur both on
the surface and deep in the interior of the Earth is called
a. earth science.
c. historical geology.
b. physical geology.
d. geological sciences.
8.
The systematic way to find answers to questions, solutions to problems, and evidence to prove or
disprove ideas and beliefs is called
a. hypothesis.
c. theory.
b. law.
d. scientific mether
9.
The actual age of a rock in years is also called the
a. absolute age.
c. real age.
b. comparative age.
d. relative age.
10.
The rigid outer layer of the Earth, which is roughly 100 kilometers, thick is called the
a. asthenosphere.
c. lithosphere.
b. atmosphere cover.
d. hydrosphere.
11.
The time required for one half the original quantity of radioactive atoms to decay is called
a. atomic mass time.
c. decomposition time.
b. half-life.
d. degradation time.
12.
The rock age that is based on whether particular layers or bodies are older or younger than others
is called
a. absolute age.
c. real age.
b. comparative age.
d. relative age.
13.
The plastic, easily deformed layer of the Earth that the plates rest on is called the
a. aslhthosphere.
c. lithosphere.
b. atmosphere cover.
d. hydrosphere.
Chapter 1—The Science of Historical Geology
14.
The crust and the mantle of the Earth make up the
a. asthenosphere.
c. lithosphere.
b. atmosphere cover.
d. hydrosphere.
15.
The boundary that is formed where two or more plates move apart from one another is called
a. convergent boundary.
c. joint boundary.
b. divergent boundary.
d. transform boundary.
16.
The great unifying theory of biology is
a. evolution.
b. natural selection.
c. meiosis.
d. inheritance.
17.
The boundary that is formed when two or more plates move toward one another is called
a. convergent boundary.
c. joint boundary.
b. divergent boundary.
d. transform boundary.
18.
The great unifying theory in geology is
a. the Big Bang theory.
b. plate tectonics.
c. continental drift.
d. rock cycle.
Gravity is an example of a/an
a. law.
b. theory.
c. principle.
d. hypothesis.
19.
20.
The oldest rocks found on the Earth were located in
a. the Himalayas.
c. the Canadian Rockies.
b. the Alps.
d. the Appalachians.
Chapter 1—The Science of Historical Geology
FILL IN THE BLANK
1.
The Earth was formed ________________ years ago.
2.
______________ geology addresses the Earth’s origin and evolution, changes in the distribution of
lands and seas, the growth and reduction of mountains, and the succession of animals and plants
through time.
3.
The _______________ ________________ is a systematic way to find answers to questions,
solutions to problems, and evidence to prove or disprove ideas and beliefs.
4.
A ________________ fits all the data in a scientific investigation and is likely to account for
observation and is likely to account for observations in the future as well as the future.
5.
To a scientist, a ______________ represents knowledge that has a very high probability of being
correct.
6.
______________________ is the time required for one half of the original quantity of radioactive
atoms to decay.
7.
Determining the ___________________ age of a rock is based on whether particular layers or
bodies are older or younger than others.
8.
The “great unifying theory” in geology is _____________ ________________.
9.
This rigid outer layer of the Earth (approximately 100 kilometers thick) includes the crust as well as
the uppermost part of the mantle. _________________________
10.
The outermost part of the lithosphere that is about 32 kilometers thick is called _______________.
11.
The zone within the Earth between 50 and 250 kilometers thick and is thought to be a zone where
the conventive flow of material occurs is called the ____________________.
12.
Charles Darwin’s proposed theory that any given species produces more organisms than can
survive to maturity is part of his theory of _______________ ________________.
13.
Distinctive shells of these invertebrates have been widely used to identify rock formation when
drilling for oil or gas. __________________
14.
Where two or more plates move apart from one another, the plate margins form _____________
boundaries.
15.
When plates grind past one another ________________ boundaries occur.
Chapter 1—The Science of Historical Geology
TRUE/FALSE
1.
Geology is the study of Earth and does not include the study of any other planet.
2.
The statement “the Mediterranean Sea was once a desert” is an example of a hypothesis.
3.
The asthenosphere is closer to the surface of the Earth than the lithosphere.
4.
There is conclusive evidence that the Mediterranean Sea was once a desert.
5.
The discovery of radioactivity enabled geologists to find the absolute age of rocks.
6.
Charles Darwin was the first individual to propose the theory of evolution.
7.
The Earth is a relativity static ball of rock that is orbiting the sun.
8.
Geology is an eclectic science drawing principles from many areas.
9.
Data collection is the first step in the scientific method.
10.
A geologic time scale was developed using relative time dating.
Chapter 1—The Science of Historical Geology
ANSWER KEY
Multiple Choice
Fill Ins
True/False
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2.
3.
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5.
6.
7.
8.
9.
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14.
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20.
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15.
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10.
c
a
d
c
b
a
b
d
a
c
b
d
a
c
b
a
a
b
a
c
4.6 billion
Historical
scientific method
hypothesis
theory
Half-life
relative
plate tectonics
lithosphere
crust
asthenosphere
natural selection
foraminifera
divergent
transform
F
T
F
T
T
F
F
T
T
T
Chapter 1—The Science of Historical Geology
RESPONSES TO QUESTIONS
ACCOMPANYING SELECTED FIGURES
No questions on figures for this chapter.