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PowerLecturePowerLectureA Microsoft PowerPoint Link Tool
forfor
academic.cengage.com/earthsci
Changing EarthChanging EarthExploring Geology
and EvolutionExploring Geologyand Evolution
55thth EditionEdition
James S. MonroeJames S. Monroe || Reed WicanderReed Wicander
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Chapter 1
UnderstandingEarth
A Dynamic andEvolving Planet
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Introduction
Geology
Geology is a complex, integratedsystem of related
parts, components, or sub-systems that interactin an organized fashion, affecting one another in
various ways.
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Introduction
The principal subsystemsof theearth are the:
Atmosphere
BiosphereHydrosphere
Lithosphere
Mantle
Core
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The interaction of these subsystems has resulted in a
dynamically changing planet in which matter andenergy are continuously recycled into different forms.
Introduction
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Geology is the study of the Earth.
Physical geology is concerned with the
materials and processes which compose andoperate on the surface of, and within, Earth.
Historical geology is concerned with the
origin andevolution of Earth's continents,oceans, atmosphere, and life.
What is geology?
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What is geology?
Geologists areemployed indiverse occupations.
Principle occupationsinclude:
Mineral and
energy resource
exploration
Solvingenvironmental
problems
Predicting
natural disasters
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Geology and theFormulation of Theories
What is a theory?
It is arrived at through thescientific method, which
involvesgathering and analyzing facts
formulating hypotheses to explain the phenomenon
testing the hypotheses
and finally proposing a theory.
Thehypotheses is a tentative explanation.
Ascientific theory is a testable explanation for some
natural phenomenon, that is supported by a large body
ofevidence.
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How Does Geology Relateto theHuman Experience?
Geology pervades oureveryday lives
and is a part of many aspects of
human experience, including the artsand literature.
The range ofenvironmental problems
and issues of concern to society
require a basic understanding ofgeology.
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How does geology affectour daily lives?
Natural Events
Economics andPoliticsOur Role as Decision
makers
Consumers andCitizens
Sustainable Development
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Global Geologic and EnvironmentalIssues Facing Humankind
Most scientists would argue
that overpopulation is thegreatest problem facing the
world today.
Increasingly large numbers of
people must be fed, housed,
and clothed, with a minimal
impact on theenvironment.
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Global Geologic and EnvironmentalIssues Facing Humankind
The greenhouseeffect is the retention of heat in the
atmosphere, which results in an increase in thetemperature of Earths surface and atmosphere, thus
producing global warming.
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Origin ofthe Universe
Did it begin with a Big Bang?
In theBig Bang theory, the
universe began approximately15 billion years ago.
An extremely dense, hot body
of matterexpanded and
cooled
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Origin ofthe Universe
How do we know? Evidence for theBig Bang:
the universe is expanding
from a central point.Theentire universe has a
pervasive and constant
background radiation,
thought to be the faintafterglow of theBig Bang.
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Our Solar System
Its Origin and Evolution
The Solar System formed from a rotating cloud ofinterstellar matter about 4.6 billion years ago.
This cloud, upon condensing, collapsed under theinfluence of gravity and flattened into a rotating disk.
The sun, planets, and moons formed within this disk.
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Earth
Its Place in Our Solar System
Earth formed from a swirling eddy of nebular
material 4.6 billion years ago, accreting as a solid
body and soon thereafterdifferentiated into a
layered planet during a period of internal heating.
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Why Earth is a Dynamic
and Evolving Planet
Earthhas continuously changed during its 4.6
billion year existenceas aresultof
interactions between its various subsystems
and cycles.
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Earth is composed of 3 concentric layers.
Core
Mantle
Crust.
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The core consists of
a small, solid innerregion
a larger,liquid, outerportion
Composed ofiron and a small amount ofnickel.
TheCore
Why Earth is a Dynamicand Evolving Planet
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Why Earth is a Dynamicand Evolving Planet
The mantle surrounds the core and
is divided into: a solid lower mantle
an asthenosphere that behavesplastically and flows slowly
a solid upper mantle.
Composed primarily ofperidotite, an igneous rockmade of olivine.
TheMantle
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Why Earth is a Dynamicand Evolving Planet
The outermost layer, the crust,
is divided into:
thick continental crust
thin oceanic crust
TheCrust
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Why Earth is a Dynamicand Evolving Planet
TheAsthenosphere
Surrounds the lower mantle
Behaves plastically and slowlyflows
Partial melting in the
asthenospheregenerates magma
(molten rock) that rises to theearths surface.
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Why Earth is a Dynamicand Evolving Planet
TheLithosphere
The crust and upper mantle make
up the lithosphere which forms thesolid outer layers of the Earth.
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Why Earth is a Dynamicand Evolving Planet
PlateTectonic Theory
The lithosphere is composed of rigid plates that
diverge, converge, or slide sideways past oneanother as they move over the asthenosphere
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Why Earth is a Dynamicand Evolving Planet
PlateTectonic Theory
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Why Earth is a Dynamicand Evolving Planet
PlateTectonic Theory
Volcanoes andearthquakes occur at the
boundaries between the plates.
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Why Earth is a Dynamicand Evolving Planet
PlateTectonic Theory
Plate tectonic theory isa unifying explanation
for many geologicfeatures andevents,helping us understandthe composition andinternal processes of
Earth on a global scale.
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The Rock Cycle
Arock is a solid aggregate of one or more minerals, as
well as non-crystalline matter such as natural glass ororganic material like coal.
There are three major groups of rocks
Igneous
Sedimentary
Metamorphic
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The Rock CycleIgneous Rocks form from the crystallization
of magma as it cools or the consolidation ofvolcanic ejecta.
Intrusive igneous rock
crystallizes beneath theearths surface.
Extrusive igneous rock
crystallizes and cools at the
earths surface. At times it
cools so fast that it forms a
glass or ash.
GraniteGranite
Intrusive Igneous RockIntrusive Igneous Rock
BasaltBasalt
Extrusive Igneous RockExtrusive Igneous Rock
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The Rock Cycle
Sedimentary Rocks are typically depositedin layers formed from:
rock/mineral fragments
precipitation of minerals from solution
the compaction of plant and animal remains.
LimestoneLimestone
Precipitation from seawaterPrecipitation from seawater
ConglomerateConglomerate
Forms from river gravelsForms from river gravels
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The Rock Cycle
Metamorphic Rocks form from alteration of
other rocks, usually by:
Heat
PressureChemically active fluids
QuartziteQuartziteGneissGneiss
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The Rock Cycle
The rock cycle illustrates the interactions between
Earths internal andexternal processes and how thethree rock groups are interrelated.
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The Rock Cycle
How are the rock cycle and plate tectonics
related?
Plate movement is the
driving mechanism of therock cycle. Plate inter-
action determines, to
someextent, which of the
three rock groups will form.
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Organic Evolution andtheHistory of Life
The theory oforganic evolution states:
that all living things are related and
havedescended with modification from organismsliving in the past.
Charles Darwin proposed that the mechanism of
natural selection results in survival reproductive age
of those organisms best suited to theirenvironment.
Fossils, the remains of once-living organisms provide
theevidence forevolution and a history of life before
humans.
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Organic Evolution
and Plate Tectonics
Together the theories of platetectonics and organic evolution
have changed the way we view
our planet.
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Geologic Time
An appreciation of the immensity of geologic time is
central to understanding theevolution of the Earthand its life.
Geologic timediffers from the humanperspective of time
Earth goes through cycles of muchlongerduration than the humanperspective of time
The immense span of timeencompassed by the Earth's
existence and geological processessets geology apart
Thegeologic time scale is thecalendar that geologists use to datepast events in Earths history.
G l i Ti d
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Geologic TimeandUniformitarianism
Uniformitarianism forms a cornerstone of geology. It is
a fundamental tenet of geology.
This principle states that the laws of nature have
remained unchanged through time and thus, thatthe processes observed today have also operated in
the past, though possibly at different rates.
Therefore, to understand and interpret geologic
events from evidence preserved in rocks,geologists
must first understand present-day processes in
rocks.
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How does the study of geology
benefitus?
Understanding how the Earths subsystems
work will help ensure the survival of thehuman species.
It will help us to understand how our
actions affect thedelicate balance betweenthese systems.
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Endof Chapter 1