ABOUT THE COURSEEnvironmental Geology Is Geology Applied to Living
The environment is the sum of all the features and conditions
surrounding an organism that may influence it. An individual’s
physical environment encompasses rocks and soil, air and
water, such factors as light and temperature, and other organisms.
One’s social environment might include a network of
family and friends, a particular political system, and a set of
social customs that affect one’s behavior.
Geology is the study of the earth. Because the earth provides
the basic physical environment in which we live, all of geology
might in one sense be regarded as environmental geology.
However, the term environmental geology is usually restricted
to refer particularly to geology as it relates directly to human
activities, and that is the focus of this book. Environmental
geology is geology applied to living. We will examine how
geologic processes and hazards influence human activities (and
sometimes the reverse), the geologic aspects of pollution and
waste-disposal problems, and several other topics.
Why Study Environmental Geology?
One reason for studying environmental geology might simply
be curiosity about the way the earth works, about the how
and why of natural phenomena. Another reason is that we are
increasingly faced with environmental problems to be solved
and decisions to be made, and in many cases, an understanding
of one or more geologic processes is essential to finding an
appropriate solution.
Of course, many environmental problems cannot be fully
assessed and solved using geologic data alone. The problems
vary widely in size and in complexity. In a specific instance,
data from other branches of science (such as biology, chemistry,
or ecology), as well as economics, politics, social priorities,
and so on may have to be taken into account. Because a variety
of considerations may influence the choice of a solution,
there is frequently disagreement about which solution is “best.”
Our personal choices will often depend strongly on our beliefs
about which considerations are most important.
ABOUT THE BOOK
An introductory text cannot explore all aspects of environmental
concerns. Here, the emphasis is on the physical constraints
imposed on human activities by the geologic processes
that have shaped and are still shaping our natural environment.
In a real sense, these are the most basic, inescapable constraints;
we cannot, for instance, use a resource that is not there, or build
a secure home or a safe dam on land that is fundamentally
unstable. Geology, then, is a logical place to start in developing
an understanding of many environmental issues. The principal
aim of this book is to present the reader with a broad overview
of environmental geology. Because geology does not exist in
a vacuum, however, the text introduces related considerations
from outside geology to clarify other ramifications of the subjects
discussed. Likewise, the present does not exist in isolation
from the past and future; occasionally, the text looks both at
how the earth developed into its present condition and where
matters seem to be moving for the future. It is hoped that this
knowledge will provide the reader with a useful foundation for
discussing and evaluating specific environmental issues, as
well as for developing ideas about how the problems should
be solved.
ORGANIZATION
The book starts with some background information: a brief
outline of earth’s development to the present, and a look at
one major reason why environmental problems today are so
pressing—the large and rapidly growing human population.
This is followed by a short discussion of the basic materials
of geology—rocks and minerals—and some of their physical
properties, which introduces a number of basic terms and concepts
that are used in later chapters.
The next several chapters treat individual processes in
detail. Some of these are large-scale processes, which may
involve motions and forces in the earth hundreds of kilometers
below the surface, and may lead to dramatic, often catastrophic
events like earthquakes and volcanic eruptions. Other
processes—such as the flow of rivers and glaciers or the blowing
of the wind—occur only near the earth’s surface, altering
the landscape and occasionally causing their own special problems. In some cases, geologic processes can be modified,
deliberately or accidentally; in others, human activities must be
adjusted to natural realities. The section on surface processes
concludes with a chapter on climate, which connects or affects
a number of the surface processes described earlier in Section
Three.
A subject of increasing current concern is the availability
of resources. A series of five chapters deals with water
resources, soil, minerals, and energy, the rates at which they are
being consumed, probable amounts remaining, and projections
of future availability and use. In the case of energy resources,
we consider both those sources extensively used in the past and
new sources that may or may not successfully replace them in
the future.
Increasing population and increasing resource consumption
lead to an increasing volume of waste to be disposed of;
thoughtless or inappropriate waste disposal, in turn, commonly
creates increasing pollution. Three chapters examine the interrelated
problems of air and water pollution and the strategies
available for the disposal of various kinds of wastes. The introduction
to this section presents some related concepts from the
field of geomedicine, linking geochemistry and health.
The final two chapters deal with a more diverse assortment
of subjects. Environmental problems spawn laws intended to
solve them; chapter 19 looks briefly at a sampling of laws and
international agreements related to geologic matters discussed
earlier in the book, and some of the problems with such laws
and accords. Chapter 20 examines geologic constraints on construction
schemes and the broader issue of trying to determine
the optimum use(s) for particular parcels of land—matters that
become more pressing as population growth pushes more people
to live in marginal places.
Of course, the complex interrelationships among geologic
processes and features mean that any subdivision into chapter-
sized pieces is somewhat arbitrary, and different instructors
may prefer different sequences or groupings (streams and
ground water together, for example). An effort has been made
to design chapters so that they can be resequenced in such ways
without great difficulty.
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2008 McGraw-Hill Higher Education