A Custom Edition (Frederick K. Lutgens Edward J. Tarbuck Denn.docx

A Custom Edition (Frederick K. Lutgens * Edward J. Tarbuck *
Dennis Tasa, Foundations of Earth Science) Sixth Edition
Written Responses:
· Unless otherwise indicated, there is a 200 word minimum
response required.
· Credible reference materials, including your course
textbook(s), may be used to complete the assessment.
· APA Information
· In-text and reference citations are required for all written
responses.
· REQUIRED FOR UPLOADED ASSIGNMENTS ONLY: title
page, margins, header, double spacing, and hanging indentation
Question 1
Wind is included along with gravity, water, and ice as an agent
of erosion. In many areas of natural beauty, statements are often
made that credit wind as having sculpted the landscape. Briefly
discuss the importance of wind as an agent of erosion, and
explain why such statements are probably inaccurate.
Question 2
When examining the geology of a region for potential useable
aquifers, what characteristics or factors would you consider?
Also, taking into account certain natural and human factors,
which areas would you avoid?
Question 3
At one time it was thought that the deep-ocean trenches at
subduction zones would be a good place for disposal of high-
level radioactive waste. Why is this not a good idea? Explain
what can happen at a subduction zone and what might occur if
the waste were buried there. (Hint: see oceanic-continental
convergence.)
Question 4
How are faults, foci (plural of focus), and epicenters related?

Faults that are experiencing no active creep (relatively
consistent yet minor movements) may be considered “safe.”
Rebut or defend this statement with what you have learned so
far about faults.
SYLLABUS
Top of Form
Bottom of Form
Content
· PRINT
· LEARNING ACTIVITIES
Collapse All
|
Expand All
· Toggle Drawer
Course Overview
Welcome to your Capella University online course, DPA8404 –
Principles of Organization Theories and Practice.
This course is designed to enhance the skills and abilities of a
public administrator in advanced practice. The topics of
analysis in this course include motivation, productivity,
diversity, group development, team building, collaboration,
coordination with outside contractors, decision-making and
communication processes, power and politics, and
organizational culture. Theory and practice are combined in a
final course project, in which learners will conduct an
organizational analysis.

VitalSource Bookshelf
This course offers e-books through the VitalSource Bookshelf.
You will access some of your readings for this course via
Bookshelf. More information on this program can be found in
the Unit 1 studies.
Course Competencies
To successfully complete this course, you will be expected to:
1. Analyze theories of organizational behavior as applied to the
field.
2. Evaluate methods of managing and enhancing culture in the
workplace based on contemporary theory.
3. Apply theories to organizations to illustrate efficacy in
practices.
4. Analyze theories of decision making for application in the
public sector.
5. Think critically and communicate effectively in
organizational settings.
· Toggle Drawer
Prerequisites
Cannot be fulfilled by transfer.
· Toggle Drawer
Grading
Course requirements include the following major independent
measures of learner competency.
Learning Activity Weights and Scoring Guides

Activity
Weight
Scoring Guide
1. Discussion Participation
40%
Discussion Participation Scoring Guide.
2. Project - Organizational Analysis Components
60%
u04a1: Project - Organizational Theory Overview
25%
Project - Organizational Theory Overview Scoring Guide.
u09a1: Project - Organizational Analysis
35%
Project - Organizational Analysis Scoring Guide.
Total:
100%
· Toggle Drawer
Final Course Grade
A = 90-100%
B = 80-89%
C = 70-79%
F = 69% and below
· Toggle Drawer
Course Materials
Required
e-Books
The following required readings are available electronically
through the VitalSource Bookshelf. To access links to your e-
readings, go to your e-books page on iGuide. You can find
additional information about downloading e-books on this
iGuide resource page.

Rainey, H. G. (2014). Understanding and managing public
organizations (5th ed.). Hoboken, NJ: Jossey-Bass.
Stillman, R. J., II (Ed.). (2010). Public administration: Concepts
and cases (9th ed.). Boston: Houghton Mifflin.
Articles
Library
The following required readings are provided to you in the
Capella University Library. Ask a Librarian for assistance with
any of these resources.
Barbuto, J. E., Jr. (2005). Motivation and transactional,
charismatic, and transformational leadership: A test of
antecedents.Journal of Leadership & Organizational
Studies, 11(4), 26–40.
Bush, P. (2005). Strategic performance management in
government: Using the balanced scorecard. Cost
Management, 19(3), 24–31.
de Reuver, R. (2006). The influence of organizational power on
conflict dynamics.Personnel Review, 35(5), 589–603.
Jones, M. (2008). A complexity science view of modern police
administration.Public Administration Quarterly, 32(3), 433–457.
Kessler, E. H. (2001). The idols of organizational theory from
Francis Bacon to the Dilbert Principle.Journal of Management
Inquiry, 10(4), 285–298.
Lindeman, N. (2008). Participation and power: Civic discourse
in environmental policy decisions.Technical Communication

Quarterly, 17(4), 455–458.
Lockwood, N. R. (2005). Workplace diversity: Leveraging the
power of difference for competitive advantage.HR
Magazine, 50(6), A1–A10.
Marques, J. F. (2007). Implementing workplace diversity and
values: What it means, what it brings.Performance
Improvement, 46(9), 5–7.
McGuigan, G. S. (2005). Information technology and electronic
government: Benefits and challenges to public
administration.Information Technology Newsletter, 16(2), 20–
23.
Morehouse, M. M. (2007). An exploration of emotional
intelligence across career arenas.Leadership & Organization
Development Journal, 28(4), 296–307.
Morrison, R. L. (2008). Negative relationships in the
workplace: Associations with organisational commitment,
cohesion, job satisfaction and intention to turnover.Journal of
Management and Organization, 14(4), 330–344.
Schaffer, B. (2008). Leadership and
motivation.SuperVision, 69(2), 6–9.
Skordoulis, R., & Dawson, P. (2007). Reflective decisions: The
use of Socratic dialogue in managing organizational
change.Management Decision, 45(6), 991–1007.
Internet
These required articles are available on the Internet. Please note
that URLs change frequently. While the URLs were current
when this course was designed, some may no longer be valid. If

you cannot access a specific link, contact your instructor for an
alternative URL. Permissions for the following links have been
either granted or deemed appropriate for educational use at the
time of course publication.
Beyer, H.J., Dziobek, C., Garrett, J. (1999) Economic and legal
considerations of optimal privatization: Case studies of
mortgage firms (DePfa Group and Fannie Mae), IMF Working
Paper, section 4, pp 14-25. Retrieved February 21, 2009, from
http://www.imf.org/external/pubs/cat/longres.cfm?sk=3029.0
Web Sites
Please note that URLs change frequently. While the URLs were
current when this course was designed, some may no longer be
valid. If you cannot access a specific link, contact your
instructor for an alternative URL. Permissions for the following
links have been either granted or deemed appropriate for
educational use at the time of course publication.
VitalSource. (2009). VitalSource Bookshelf (Version 5.1.5)
[Computer software]. Available from
http://www.vitalsource.com/software/bookshelf
© 2011 Pearson Education, Inc.
Foundations of Earth
Science, 6e
Lutgens, Tarbuck, & Tasa

Restless Earth:
Earthquakes, Geologic
Structures, and Mountain
Building
Foundations, 6e - Chapter 6
Stan Hatfield
Southwestern Illinois College
What is an earthquake?
• An earthquake is the vibration of
Earth produced by the rapid release
of energy
• Energy released radiates in all
directions from its source, the focus

• Energy is in the form of waves
• Sensitive instruments around the
world record the event
Earthquake focus
and epicenter
• Earthquakes and faults
• Movements that produce earthquakes
are usually associated with large
fractures in Earth’s crust called faults
• Most of the motion along faults can
be explained by the plate tectonics
theory

• Elastic rebound
• Mechanism for earthquakes was first
explained by H. F. Reid
• Rocks on both sides of an existing fault
are deformed by tectonic forces
• Rocks bend and store elastic energy
• Frictional resistance holding the rocks
together is overcome
• Elastic rebound
• Earthquake mechanism
• Slippage at the weakest point (the focus)
occurs
• Vibrations (earthquakes) occur as the

deformed rock “springs back” to its original
shape (elastic rebound)
• Foreshocks and aftershocks
• Adjustments that follow a major
earthquake often generate smaller
earthquakes called aftershocks
• Small earthquakes, called foreshocks,
often precede a major earthquake by
days or, in some cases, by as much as
several years

Seismology
• The study of earthquake waves,
seismology, dates back almost 2000
years to the Chinese
• Seismographs, instruments that record
seismic waves
• Record the movement of Earth in
relation to a stationary mass on a
rotating drum or magnetic tape
Seismology
• Seismographs
• More than one type of seismograph is
needed to record both vertical and

horizontal ground motion
• Records obtained are called
seismograms
• Types of seismic waves
• Surface waves
• Travel along the outer part of Earth
Seismology
• Surface waves
• Complex motion
• Cause greatest destruction
• Exhibit greatest amplitude and slowest
velocity

Seismology
• Body waves
• Travel through Earth’s interior
• Two types based on mode of travel
• Primary (P) waves
• Push-pull (compress and expand)
motion, changing the volume of the
intervening material
• Travel through solids, liquids, and gases
Seismology
• Body waves
• Secondary (S) waves
• “Shake” motion at right angles to their
direction of travel

• Travel only through solids
• Slower velocity than P waves
Locating an earthquake
• Terms
• Focus—The place within Earth where
earthquake waves originate
• Epicenter—Location on the surface
directly above the focus
• Epicenter is located using the
difference in velocities of P and S
waves
• Locating the epicenter of an earthquake
• Three station recordings are needed to locate

an epicenter
• Each station determines the time interval
between the arrival of the first P wave and the
first S wave at their location
• A travel-time graph is used to determine each
station’s distance to the epicenter
Seismogram showing P, S,
and surface waves
A travel-time graph
• Locating the epicenter of an earthquake
• A circle with a radius equal to the

distance to the epicenter is drawn
around each station
• The point where all three circles
intersect is the earthquake epicenter
Finding an earthquake
epicenter
• Earthquake belts
• About 95 percent of the energy released
by earthquakes originates in a few
relatively narrow zones that wind around
the globe
• Major earthquake zones include the
Circum-Pacific belt and the Oceanic-

Ridge system
Measuring the size
of earthquakes
• Two measurements that describe the
size of an earthquake are
• Intensity—A measure of the degree of
earthquake shaking at a given locale
based on the amount of damage
• Magnitude—Estimates the amount of
energy released at the source of the
earthquake
Measuring the size
of earthquakes
• Intensity scales
• Modified Mercalli Intensity Scale was
developed using California buildings as
its standard

• The drawback of intensity scales is that
destruction may not be a true measure
of the earthquake’s actual severity
Measuring the size
of earthquakes
• Magnitude scales
• Richter magnitude—Concept introduced
by Charles Richter in 1935
• Richter scale
• Based on the amplitude of the largest
seismic wave recorded
• Accounts for the decrease in wave
amplitude with increased distance
Measuring the size

of earthquakes
• Richter scale
• Magnitudes less than 2.0 are not felt by
humans
• Each unit of Richter magnitude increase
corresponds to a tenfold increase in wave
amplitude and a 32-fold energy increase
Measuring the size
of earthquakes
• Other magnitude scales
• Several “Richter-like” magnitude scales
have been developed
• Moment magnitude was developed because
none of the “Richter-like” magnitude scales
adequately estimate very large earthquakes

• Derived from the amount of displacement
that occurs along a fault
Earthquake destruction
• Amount of structural damage
attributable to earthquake vibrations
depends on
• Intensity and duration of the vibrations
• Nature of the material upon which the
structure rests
• Design of the structure
• Destruction from seismic vibrations
• Ground shaking

• Regions within 20 – 50 kilometers of the
epicenter will experience about the same
intensity of ground shaking
• However, destruction varies
considerably mainly due to the nature of
the ground on which the structures are
built
Damage caused by the 1964
Anchorage, Alaska quake
Figure 6.13
• Liquefaction of the ground
• Unconsolidated materials saturated with
water turn into a mobile fluid
• Tsunamis, or seismic sea waves

• Destructive waves that are often
inappropriately called “tidal waves”
• Tsunamis, or seismic sea waves
• Result from vertical displacement along
a fault located on the ocean floor or a
large undersea landslide triggered by an
earthquake
• In the open ocean height is usually less
than 1 meter
• In shallower coastal waters the water
piles up to heights over 30 meters
Formation of a tsunami

• Landslides and ground subsidence
• Fire
Earth’s layered structure
• Layers are defined by composition
• Three principal compositional layers
• Crust—The comparatively thin outer skin
that ranges from 3 kilometers (2 miles) at
the oceanic ridges to 70 kilometers
(40 miles in some mountain belts)
• Mantle—A solid rocky (silica-rich) shell that
extends to a depth of about 2900 kilometers
(1800 miles)

• Layers are defined by composition
• Three principal compositional layers
• Core—An iron-rich sphere having a radius
of 3486 kilometers (2161 miles)
• Layers defined by physical properties
• With increasing depth, Earth’s interior is
characterized by gradual increases in
temperature, pressure, and density
• Main layers of Earth’s interior are based
on physical properties and hence
mechanical strength
• Lithosphere (sphere of rock)
• Consists of the crust and uppermost mantle

• Relatively cool, rigid shell
• Averages about 100 kilometers in thickness,
but may be 250 kilometers or more thick
beneath the older portions of the continents
• Asthenosphere (weak sphere)
• Beneath the lithosphere, in the upper
mantle to a depth of about 600 kilometers
• Small amount of melting in the upper
portion mechanically detaches the
lithosphere from the layer below allowing
the lithosphere to move independently of
the asthenosphere
• Mesosphere or lower mantle
• Rigid layer between the depths of

660 kilometers and 2900 kilometers
• Rocks are very hot and capable of very
gradual flow
• Outer core
• Composed mostly of an iron-nickel alloy
• Liquid layer
• 2270 kilometers (1410 miles) thick
• Convective flow within generates Earth’s
magnetic field
• Inner core

• Sphere with a radius of 3486 kilometers
(2161 miles)
• Stronger than the outer core
• Behaves like a solid
Deformation
• Deformation is a general term that
refers to all changes in the original
form and/or size of a rock body
• Most crustal deformation occurs
along plate margins
• Deformation involves
• Stress—Force applied to a given area

Deformation
• How rocks deform
• General characteristics of rock
deformation
• Elastic deformation—The rock returns to
nearly its original size and shape when the
stress is removed
• Once the elastic limit (strength) of a rock is
surpassed, it either flows (ductile
deformation) or fractures (brittle
deformation)
Folds
• During crustal deformation rocks are
often bent into a series of wave-like
undulations called folds
• Characteristics of folds
• Most folds result from compressional
stresses which shorten and thicken the

crust
Folds
• Common types of folds
• Anticline—Upfolded or arched rock
layers
• Syncline—Downfolds or troughs of
rock layers
• Depending on their orientation,
anticlines and synclines can be
described as
• Symmetrical, asymmetrical, or
recumbent (an overturned fold)
Anticlines and synclines
Folds

• Other types of folds
• Dome
• Upwarped displacement of rocks
• Circular or slightly elongated structure
• Oldest rocks in center, younger rocks on
the flanks
Folds
• Other types of folds
• Basin
• Circular or slightly elongated structure
• Downwarped displacement of rocks
• Youngest rocks are found near the center,
oldest rocks on the flanks

Faults
• Faults are fractures in rocks along
which appreciable displacement has
taken place
• Sudden movements along faults are the
cause of most earthquakes
• Classified by their relative movement
which can be
• Horizontal, vertical, or oblique
Faults
• Types of faults
• Dip-slip faults
• Movement is mainly parallel to the dip of the
fault surface
• May produce long, low cliffs called fault
scarps
• Parts of a dip-slip fault include the hanging
wall (rock surface above the fault) and the
footwall (rock surface below the fault)

Faults
• Types of dip-slip faults
• Normal fault
• Hanging wall block moves down
relative to the footwall block
• Accommodates lengthening or
extension of the crust
• Larger scale normal faults are
associated with structures called
fault-block mountains
Normal fault
Faults
• Types of dip-slip faults

• Reverse and thrust faults
• Hanging wall block moves up relative to
the footwall block
• Reverse faults have dips greater than 45o
and thrust faults have dips less than 45o
• Strong compressional forces
Reverse fault
Faults
• Strike-slip fault
• Dominant displacement is horizontal
and parallel to the strike of the fault
• Types of strike-slip faults
• Right-lateral—As you face the fault, the
opposite side of the fault moves to the
right
• Left-lateral—As you face the fault, the

opposite side of the fault moves to the
left
Strike-Slip fault
Faults
• Strike-slip fault
• Transform fault
• Large strike-slip fault that cuts through
the lithosphere
• Accommodates motion between two
large crustal plates
The San
Andreas
Fault
System

Mountain building
• Orogenesis—The processes that
collectively produce a mountain belt
• Include folding, thrust faulting,
metamorphism, and igneous activity
• Compressional forces producing
folding and thrust faulting
• Metamorphism
• Igneous activity
Mountain building at
convergent boundaries
• Island arcs
• Where two ocean plates converge

and one is subducted beneath the
other
• Volcanic island arcs result from the
steady subduction of oceanic
lithosphere
• Continued development can result in the
formation of mountainous topography
consisting of igneous and metamorphic
rocks
Volcanic island arc
• Andean-type mountain building
• Mountain building along continental
margins
• Involves the convergence of an oceanic

plate and a plate whose leading edge
contains continental crust
• Exemplified by the Andes Mountains
• Building a volcanic arc
• Subduction and partial melting of mantle
rock generates primary magmas
• Differentiation of magma produces
andesitic volcanism dominated by
pyroclastics and lavas
• A large percentage of the magma never
reaches the surface and is emplaced as
plutons
Andean-type plate margin

Subduction and
mountain building
• Development of an accretionary wedge
• An accretionary wedge is a chaotic
accumulation of deformed and thrust-
faulted sediments and scraps of oceanic
crust
• Prolonged subduction may thicken an
accretionary wedge enough so it protrudes
above sea level
Continental collisions
• Two lithospheric plates, both carrying

continental crust
• Continental collisions result in the
development of compressional
mountains that are characterized by
shortened and thickened crust
• Most compressional mountains exhibit
a region of intense folding and thrust
faulting called a fold-and-thrust-belt
• Himalayan Mountains
• Youthful mountains—Collision began
about 45 million years ago
• India collided with Eurasian plate
• Similar but older collision occurred
when the European continent collided
with the Asian continent to produce the
Ural mountains

• Appalachian Mountains
• Formed long ago and substantially
lowered by erosion
• Resulted from a collision among North
America, Europe, and northern Africa
Terranes and
mountain building
• Another mechanism of orogenesis
• The nature of terranes
• Small crustal fragments collide and
merge with continental margins
• Accreted crustal blocks are called
terranes (any crustal fragments whose

geologic history is distinct from that of
the adjoining terranes)
Terranes and
mountain building
• The nature of terranes
• Prior to accretion some of the fragments
may have been microcontinents
• Others may have been island arcs,
submerged crustal fragments, extinct
volcanic islands, or submerged oceanic
plateaus
Terranes and
mountain building
• Accretion and orogenesis

• As oceanic plates move they carry
embedded oceanic plateaus, island
arcs, and microcontinents to Andean-
type subduction zones
• Thick oceanic plates carrying oceanic
plateaus or “lighter” igneous rocks of
island arcs may be too buoyant to
subduct
Collision and
accretion
of an
island arc
Terranes and
mountain building

• Accretion and orogenesis
• Collision of the fragments with the
continental margin deforms both blocks
adding to the zone of deformation and to
the thickness of the continental margin
• Many of the terranes found in the North
American Cordillera were once
scattered throughout the eastern Pacific
End of Chapter 6
Science, 6e

Plate Tectonics: A
Scientific Theory
Unfolds
Stan Hatfield
Continental Drift: An idea
before its time
• Alfred Wegener
• First proposed his continental drift
hypothesis in 1915
• Published The Origin of Continents
and Oceans
• Continental drift hypothesis

• Supercontinent called Pangaea began
breaking apart about 200 million
years ago
Pangaea approximately 200
million years ago
Continental Drift: An idea
before its time
• Continental drift hypothesis
• Continents “drifted” to present
positions
• Evidence used in support of
continental drift hypothesis
• Fit of the continents
• Fossil evidence
• Rock type and structural similarities
• Paleoclimatic evidence

Fossil evidence supporting
continental drift
Matching mountain ranges
The great debate
• Objections to the continental drift
hypothesis
• Lack of a mechanism for moving
continents
• Wegener incorrectly suggested that
continents broke through the ocean
crust, much like ice breakers cut
through ice
• Strong opposition to the hypothesis
from the scientific community

The great debate
• Continental drift and the scientific
method
• Wegener’s hypothesis was correct in
principle, but contained incorrect
details
• A few scientists considered Wegener’s
ideas plausible and continued the
search
Plate Tectonics: A modern
version of an old idea

• Earth’s major plates
• Associated with Earth’s strong, rigid
outer layer
• Known as the lithosphere
• Consists of uppermost mantle and
overlying crust
• Overlies a weaker region in the mantle
called the asthenosphere
• Seven major lithospheric plates
• Plates are in motion and continually
changing in shape and size
• Largest plate is the Pacific plate

• Several plates include an entire
continent plus a large area of seafloor
Earth’s tectonic plates
• Plates move relative to each other at a
very slow but continuous rate
• About 5 centimeters (2 inches) per year
• Cooler, denser slabs of oceanic lithosphere
descend into the mantle

• Plate boundaries
• Interactions among individual plates
occur along their boundaries
• Types of plate boundaries
• Divergent plate boundaries
(constructive margins)
• Convergent plate boundaries
(destructive margins)
• Transform fault boundaries
(conservative margins)
Divergent plate boundaries
• Most are located along the crests of
oceanic ridges
• Oceanic ridges and seafloor spreading
• Along well-developed divergent plate
boundaries, the seafloor is elevated

forming oceanic ridges
• Oceanic ridges and seafloor
spreading
• Seafloor spreading occurs along the
oceanic ridge system
• Spreading rates and ridge
topography
• Ridge systems exhibit topographic
differences
• These differences are controlled by
spreading rates
Divergent plate boundary

• Continental rifting
• Splits landmasses into two or more
smaller segments along a
continental rift
• Examples include the East African rift
valleys and the Rhine Valley in
northern Europe
• Produced by extensional forces
acting on lithospheric plates
Continental
rifting
Convergent plate boundaries

• Older portions of oceanic plates are
returned to the mantle in these
destructive plate margins
• Surface expression of the descending
plate is an ocean trench
• Also called subduction zones
• Average angle of subduction =
45 degrees
World’s oceanic trenches
and ridge system
• Types of convergent boundaries
• Oceanic-continental convergence

• Denser oceanic slab sinks into the
asthenosphere
• Along the descending plate partial melting of
mantle rock generates magma
• Resulting volcanic mountain chain is called
a continental volcanic arc (Andes and
Cascades)
Oceanic-continental convergence
• Oceanic-oceanic convergence
• When two oceanic slabs converge, one

descends beneath the other
• Often forms volcanoes on the ocean floor
• If the volcanoes emerge as islands, a
volcanic island arc is formed (Japan,
Aleutian islands, and Tonga islands)
Oceanic-oceanic
convergence
• Continental-continental convergence
• Less dense, buoyant continental
lithosphere does not subduct
• Resulting collision between two continental
blocks produces mountains (Himalayas,

Alps, and Appalachians)
Continental-continental
convergence
Transform fault boundaries
• Plates slide past one another and no
new lithosphere is created or destroyed
• Transform faults
• Most join two segments of a mid-ocean
ridge along breaks in the oceanic crust
known as fracture zones

Transform fault boundaries
• Transform faults
• A few (the San Andreas Fault and the
Alpine Fault of New Zealand) cut
through continental crust
Transform faults
San Andreas Fault near
Taft, California

Testing the plate
tectonics model
• Evidence from ocean drilling
• Some of the most convincing
evidence confirming seafloor
spreading has come from drilling
directly into ocean-floor sediment
• Age of deepest sediments
• Thickness of ocean-floor sediments
verifies seafloor spreading
Testing the plate
tectonics model
• Hot spots and mantle plumes

• Caused by rising plumes of mantle
material
• Volcanoes can form over them
(Hawaiian Island chain)
• Mantle plumes
• Long-lived structures
• Some originate at great depth, perhaps at
the mantle-core boundary
The Hawaiian Islands
Testing the plate
tectonics model
• Paleomagnetism

• Iron-rich minerals become magnetized
in the existing magnetic field as they
crystallize
• Rocks that formed millions of years
ago contain a “record” of the direction
of the magnetic poles at the time of
their formation
Testing the plate
tectonics model
• Apparent polar wandering
• Lava flows of different ages indicated
several different magnetic poles
• Polar wandering paths are more readily
explained by the theory of plate

tectonics
Polar Wandering paths for
Eurasia and North America
Testing the plate
tectonics model
• Geomagnetic reversals
• Earth’s magnetic field periodically
reverses polarity—the north magnetic
pole becomes the south magnetic pole,
and vice versa
• Dates when the polarity of Earth’s
magnetism changed were determined

from lava flows
Testing the plate
tectonics model
• Geomagnetic reversals
• Geomagnetic reversals are recorded in
the ocean crust
• In 1963 Vine and Matthews tied the
discovery of magnetic stripes in the
ocean crust near ridges to Hess’s
concept of seafloor spreading
Paleomagnetic reversals
recorded in oceanic crust

What drives plate motions?
• Researchers agree that convective
flow in the mantle is the basic driving
force of plate tectonics
• Forces that drive plate motion
• Slab-pull
• Ridge-push
Some of the forces
that act on plates
What drives plate motions?

• Models of plate-mantle convection
• Any model must be consistent with
observed physical and chemical
properties of the mantle
• Models
• Layering at 660 kilometers
• Whole-mantle convection
End of Chapter 5
Science, 6e

Glacial and Arid
Landscapes
Stan Hatfield
Glaciers
• Glaciers are parts of two basic cycles
• Hydrologic cycle
• Rock cycle
• Glacier—A thick mass of ice that
originates on land from the
accumulation, compaction, and
recrystallization of snow

Glaciers
• Types of glaciers
• Valley (alpine) glaciers
• Exist in mountainous areas
• Flow down a valley from an
accumulation center at its head
• Ice sheets
• Exist on a larger scale than valley
glaciers
• Two major ice sheets on Earth are over
Greenland and Antarctica
Glaciers
• Types of glaciers
• Ice sheets
• Often called continental ice sheets
• Ice flows out in all directions from one or
more snow accumulation centers
• Other types of glaciers
• Icecaps
• Outlet glaciers

• Piedmont glaciers
Present-day continental ice
sheets
How glaciers move
• Movement is referred to as flow
• Two basic types
• Plastic flow
• Occurs within the ice
• Basal slip
• Entire ice mass slipping along the
ground
• Most glaciers are thought to move by

this process
How glaciers move
• Movement is referred to as flow
• Zone of fracture
• Occurs in the uppermost 50 meters
• Tension causes crevasses to form in
brittle ice
• Rates of glacial movement
• Average velocities vary considerably from one
glacier to another
How glaciers move
• Rates of glacial movement
• Rates of up to several meters per day
• Budget of a glacier

• Zone of accumulation—The area where
a glacier forms
• Elevation of the snowline varies greatly
How glaciers move
• Zone of wastage—The area where there
is a net loss to the glacier due to
• Melting
• Calving—The breaking off of large pieces of
ice (icebergs where the glacier has reached
the sea)
How glaciers move

• Balance between accumulation at the
upper end of the glacier, and loss at the
lower end is referred to as the glacial
budget
• If accumulation exceeds loss (called
ablation), the glacial front advances
• If ablation increases and/or accumulation
decreases, the ice front will retreat
The glacial budget
Glacial erosion
• Glaciers are capable of great erosion
and sediment transport
• Glaciers erode the land primarily in
two ways
• Plucking—Lifting of rocks
• Abrasion
• Rocks within the ice acting like sandpaper

to smooth and polish the surface below
Glacial erosion
Glacial erosion
• Glacial erosion
• Glacial abrasion produces
• Rock flour (pulverized rock)
• Glacial striations (grooves in the bedrock)
Glacial abrasion
Glacial erosion

• Landforms created by glacial erosion
• Erosional features of glaciated
valleys
• Hanging valleys
• Cirques
• Tarns
• Fiords
• Arêtes
• Horns
Glaciated
topography
The Matterhorn in
the Swiss Alps

A fiord in Norway
Glacial deposits
• Glacial drift—Refers to all sediments of
glacial origin
• Types of glacial drift
• Till—Material that is deposited directly by
the ice
• Stratified drift—Sediments laid down by
glacial meltwater
Glacial till is
typically
unstratified
and unsorted

Glacial deposits
• Landforms made of till
• Moraines
• Layers or ridges of till
• Moraines produced by alpine glaciers
• Lateral moraine
• Medial moraine
Glacial deposits
• Other types of moraines
• End moraine—Terminal or recessional
• Ground moraine

Glacial depositional features
Glacial deposits
• Drumlins
• Smooth, elongated, parallel hills
• Steep side faces the direction from which
the ice advanced
• Occur in clusters called drumlin fields
Glacial deposits
• Landforms made of stratified drift
• Outwash plains (with ice sheets) and
valley trains (when in a valley)
• Broad ramp-like surface composed of
stratified drift deposited by meltwater

leaving a glacier
• Located adjacent to the downstream edge
of most end moraines
• Often pockmarked with depressions called
kettles
Glacial deposits
• Landforms made of stratified drift
• Ice-contact deposits
• Deposited by meltwater flowing over, within,
and at the base of motionless ice
• Features include
• Kames
• Eskers
Glaciers of the past

• Ice Age
• Ice covered 30 percent of Earth’s
land area
• Ice age began between 2–3 million years
ago
• Most of the major glacial episodes
occurred during a division of geologic
time called the Pleistocene epoch
Maximum extent of ice
during the Ice Age
Glaciers of the past
• Indirect effects of Ice Age glaciers
• Forces migration of animals and
plants
• Changes in stream courses
• Rebounding upward of the crust in

former centers of ice accumulation
• Worldwide change in sea level
• Climatic changes
Deserts
• Dry regions cover 30 percent of
Earth’s land surface
• Distribution and causes of dry lands
• Two climatic types are commonly
recognized
• Desert or arid
• Steppe or semiarid
Desert and steppe
regions of the world

Deserts
• Dry lands are concentrated in two
regions
• Subtropics
• Low-latitude deserts
• Areas of high pressure and sinking air
that is compressed and warmed
Deserts
• Dry lands are concentrated in two
regions
• Middle-latitudes
• Located in the deep interiors of continents
• High mountains in the path of the prevailing
winds produce a rainshadow desert

Rainshadow desert
Deserts
• Role of water in arid climates
• Most streambeds are dry most of the
time
• Desert streams are said to be
ephemeral
• Carry water only during periods of
rainfall
• Different names are used for desert
streams in various region
• Wash and arroyo (western United
States)
• Wadi (Arabia and North Africa)

Deserts
• Ephemeral streams
• Different names are used for desert streams
in various regions
• Donga (South America)
• Nullah (India)
• Desert rainfall
• Rain often occurs as heavy showers
Deserts
• Desert rainfall
• Because desert vegetative cover is sparse,
runoff is largely unhindered and flash floods
are common

• Poorly integrated drainage systems and
streams lack an extensive system of
tributaries
• Most of the erosion work in a desert is done
by running water
A dry channel contains water only
following heavy rain
Basin and Range: Evolution
of a desert landscape
• Characterized by interior drainage
• Landscape evolution in the Basin and
Range region
• Uplift of mountains—Block faulting
• Interior drainage into basins produces
• Alluvial fans

• Bajadas
• Playas and playa lakes
Basin and Range: Evolution
of a desert landscape
• Landscape evolution in the Basin and
Range region
• Ongoing erosion of the mountain mass
• Produces sediment that fills the basin
• Diminishes local relief
• Produces isolated erosional remnants
called inselbergs
Wind erosion

• Transportation of sediment by wind
• Differs from that of running water in
two ways
• Wind is less capable of picking up and
transporting coarse materials
• Wind is not confined to channels and can
spread sediment over large areas
Wind erosion
• Transportation of sediment by wind
• Mechanisms of transport
• Bedload
• Saltation—skipping and bouncing along
the surface
• Particles larger than sand are usually not
transported by wind
• Suspended load

Wind erosion
• Mechanisms of transport
• Deflation
• Lifting of loose material
• Deflation produces blowouts (shallow
depressions) and desert pavement (a
surface of coarse pebbles and cobbles)
• Wind is a relatively insignificant
erosional agent when compared to
water
Creation of blowouts by deflation
Formation of
desert pavement

Wind deposits
• Wind deposits
• Significant depositional landforms
are created by wind in some areas
• Two types of wind deposits
• Dunes
• Mounds or ridges of sand
• Often asymmetrically shaped
• Windward slope is gently inclined and
the leeward slope is the slip face
Sand dunes near
Preston Mesa, Arizona
Wind deposits
• Wind deposits

• Two types of wind deposits
• Loess
• Blankets of windblown silt
• Two primary sources are deserts and
glacial outwash deposits
• Extensive deposits occur in China and
the central United States
Loess deposits in
southern Illinois
End of Chapter 4
Science, 6e

Landscapes Fashioned
by Water
Stan Hatfield
Earth’s external processes
• Weathering, mass wasting, and
erosion are all called external
processes because they occur at or
near Earth’s surface
• Internal processes, such as

mountain building and volcanic
activity, derive their energy from
Earth’s interior
Mass wasting: The
work of gravity
• Mass wasting is the downslope
movement of rock and soil due to
gravity
• Controls and triggers of mass
wasting
• Water — reduces the internal resistance
of materials and adds weight to a slope
• Oversteepening of slopes
Mass wasting: The
work of gravity
• Controls and triggers of mass

wasting
• Removal of vegetation
• Root systems bind soil and regolith
together
• Earthquakes
• Earthquakes and aftershocks can dislodge
large volumes of rock and unconsolidated
material
Water cycle
• The hydrologic cycle is a summary of
the circulation of Earth’s water
supply
• Processes in the water cycle
• Precipitation
• Evaporation
• Infiltration
• Runoff

• Transpiration
The hydrologic cycle
Running water
• Streamflow
• The ability of a stream to erode and
transport materials is determined by
velocity
• Factors that determine velocity
• Gradient, or slope
• Channel characteristics including shape,
size, and roughness

Running water
• Streamflow
• Factors that determine velocity
• Discharge—The volume of water moving
past a given point in a certain amount of
time
• Changes along a stream
• Cross-sectional view of a stream is
called the profile
• Viewed from the head (headwaters or
source) to the mouth of a stream
Running water
• Changes from upstream to downstream
• Profile
• Profile is a smooth curve

• Gradient decreases downstream
• Factors that increase downstream
• Velocity
• Discharge
• Channel size
Longitudinal profile
of California’s Kings River
Base level
• Base level and stream erosion
• Base level is the lowest point to which a
stream can erode
• Two general types of base level
• Ultimate (sea level)

• Local or temporary
Base level
• Base level and stream erosion
• Changing conditions causes
readjustment of stream activities
• Raising base level causes deposition
• Lowering base level causes erosion
Adjustment of base level
to changing conditions
The work of streams
• Stream erosion

• Lifting loosely consolidated particles by
• Abrasion
• Dissolution
• Stronger currents lift particles more
effectively
The work of streams
• Transport of sediment by streams
• Transported material is called the
stream’s load
• Types of load
• Dissolved load
• Suspended load
• Bed load
• Capacity—the maximum load a stream
can transport

The work of streams
• Competence
• Indicates the maximum particle size a
stream can transport
• Determined by the stream’s velocity
The work of streams
• Deposition of sediment by a stream
• Caused by a decrease in velocity
• Competence is reduced
• Sediment begins to drop out
• Stream sediments
• Generally well sorted
• Stream sediments are known as alluvium
The work of streams

• Delta—Body of sediment where a
stream enters a lake or the ocean
• Results from a sudden decrease in velocity
• Natural levees—Form parallel to the
stream channel by successive floods
over many years
Structure of a simple delta
Natural levees
The work of streams
• Floodplain deposits

• Back swamps
• Yazoo tributaries
Stream valleys
• The most common landforms on
Earth’s surface
• Two general types of stream valleys
• Narrow valleys
• V-shaped
• Downcutting toward base level
• Features often include rapids and waterfalls
V-shaped valley of the
Yellowstone River
Stream valleys

• Two general types of stream valleys
• Wide valleys
• Stream is near base level
• Downward erosion is less dominant
• Stream energy is directed from side to side
forming a floodplain
Stream valleys
• Features of wide valleys often include
• Floodplains
• Depositional floodplains
• Meanders
• Cut banks and point bars
• Cutoffs and oxbow lakes

Oxbow lakes and meanders in a
wide stream valley
Drainage basins and patterns
• Drainage networks
• Land area that contributes water to the
stream is the drainage basin
• Imaginary line separating one basin
from another is called a divide
Drainage basin of the
Mississippi River
Drainage basins and patterns
• Drainage pattern

• Pattern of the interconnected network of
streams in an area
• Common drainage patterns
• Dendritic
• Radial
• Rectangular
• Trellis
Drainage patterns
Floods and flood control
• Floods and flood control
• Floods are the most common and most
destructive geologic hazard
• Causes of flooding
• Result from naturally occurring and human-

induced factors
• Causes include heavy rains, rapid snow
melt, dam failure, topography, and surface
conditions
Water beneath the surface
• Largest freshwater reservoir for
humans
• Geological roles
• As an erosional agent, dissolving by
groundwater produces
• Sinkholes
• Caverns
• An equalizer of stream flow

Distribution of fresh water in
the hydrosphere
• Distribution and movement of
groundwater
• Distribution of groundwater
• Belt of soil moisture
• Zone of aeration
• Unsaturated zone
• Pore spaces in the material are filled
mainly with air
• Distribution and movement of

groundwater
• Distribution of groundwater
• Zone of saturation
• All pore spaces in the material are filled
with water
• Water within the pores is groundwater
• Water table — The upper limit of the zone of
saturation
Features associated with
subsurface water
• Movement of groundwater
• Porosity
• Percentage of pore spaces

• Determines how much groundwater can be
stored
• Movement of groundwater
• Permeability
• Ability to transmit water through connected
pores
• Aquitard — An impermeable layer of
material
• Aquifer — A permeable layer of material
• Springs
• Hot springs
• Water is 6 – 9 °C warmer than the mean air

temperature of the locality
• Heated by cooling of igneous rock
• Geysers
• Intermittent hot springs
• Water turns to steam and erupts
Wintertime eruption of Old
Faithful
• Wells
• Pumping can cause a drawdown (lowering)
of the water table
• Pumping can form a cone of depression in

the water table
• Artesian wells
• Water in the well rises higher than the
initial groundwater level
• Artesian wells act as “natural pipelines”
moving water from remote areas of
recharge great distances to the points of
discharge
Formation of a cone
of depression

An artesian well resulting
from an inclined aquifer
• Environmental problems associated
with groundwater
• Treating it as a nonrenewable resource
• Land subsidence caused by its withdrawal
• Contamination
• Geologic work of groundwater
• Groundwater is often mildly acidic

• Contains weak carbonic acid
• Dissolves calcite in limestone
• Caverns
• Formed by dissolving rock beneath Earth’s
surface
• Formed in the zone of saturation
• Caverns
• Features found with caverns
• Form in the zone of aeration
• Composed of dripstone
• Common features include stalactites
(hanging from the ceiling) and stalagmites
(growing upward from the floor)

Stalactites and stalagmites in
Carlsbad Caverns National Park
• Karst topography
• Formed by dissolving rock at, or near,
Earth’s surface
• Common features
• Sinkholes – surface depressions
• Sinkholes form by dissolving bedrock and
caver collapse
• Caves and caverns
• Area lacks good surface drainage

Features of karst topography
End of Chapter 3

A Custom Edition (Frederick K. Lutgens Edward J. Tarbuck Denn.docx

Recommended

Recommended

More Related Content

Similar to A Custom Edition (Frederick K. Lutgens Edward J. Tarbuck Denn.docx

Similar to A Custom Edition (Frederick K. Lutgens Edward J. Tarbuck Denn.docx (20)

More from evonnehoggarth79783

More from evonnehoggarth79783 (20)

Recently uploaded

Recently uploaded (20)

A Custom Edition (Frederick K. Lutgens Edward J. Tarbuck Denn.docx