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UNIT 19
HIGHER LATITUDE (D AND E) AND HIGH-ALTITUDE (H) CLIMATES
Unit Overview
This unit examines the “cool” climates, which occur either in the upper-middle to higher latitudes, or at
high-elevation locales, or both. The main sections are:
•
The major humid microthermal (D) climates
•
The polar (E) climates
•
High-altitude (H) climates
The D climates are located in the middle latitudes, predominantly in the interior portions of Northern
Hemisphere continents. The E climates are located poleward of the D climates and receive little
precipitation because of the lack of water vapour in the air. The H climates are located at high elevations,
and as a result are relatively cold compared to surrounding climates. H climates can be considered
anomalies when viewed from the regional perspective. Finally, owing to the location of pollutant-emitting
facilities in the D climates and the prevalent westerly winds, acid precipitation is an important
geographically displaced environmental problem in this zone.
Teaching Objectives
•
To expand the discussion of typical D, E, and H climates and to interpret representative
climographs for those zone
•
To highlight a major environmental-climatic problem of many climate regions: acid
precipitation
•
To characterize the general influence of altitude on climatic conditions
Lecture Outline
•
•
•
The Major Humid Microthermal (D) Climates
o
The Humid Continental (Dfa/Dwa, Dfb/Dwb) climate
o
The Taiga (Dfc/Dwc, Dfd/Dwd) climate
The Polar (E) Climates
o
The Tundra (ET) climate
o
The Icecap (EF) climate
High-Altitude (H) Climate
o
Vertical zonation
Media Resources
Environment Canada’s Acid Rain Site: http://www.ec.gc.ca/acidrain
Overview of the Chemical Components of Acid Precipitation: http://www.epa.gov/airmarkets/acidrain
World Climates: http://www.blueplanetbiomes.org/climate.htm
Review Questions
1. What are humid microthermal climates (D Climates) characterized by?
2. What are the two groups that microthermal climates are divided into?
3. What does taiga mean? What is permafrost?
4. What are some of the effects of long lasting snow?
5. Which area of North America is most effected acid precipitation? (The Perspectives on the
Human Environment reading and map will help)
6. Explain the differences between the tundra (ET) climate and the icecap (EF) climate.
7. Look at the climograph in Figure 19.8. Explain why Resolute, NWT is considered a Polar (ET)
climate.
8. Explain vertical zonation. Which climate does this have a large effect on?
9. Why do temperatures decrease with elevation? Does snow have a role?
10. Look at figure 19.10. Explain why two such different climates (desert and tropical) both occur at
the same altitude (below 1200 metres).
Possible Assignments
•
Use the Internet or other source to find the average monthly temperatures and precipitation for
your area or another area of interest to you and create a climograph. Is the climate a D, E or H
climate? A site you may find useful is: http://www.worldclimate.com.
PowerPoint Lecture Guide
First Photo
Climatic boundary on the ground: the moist H (highland) region of the Kenya Highlands,
foreground, meets BS (steppe) climate on the Rift Valley floor west of Nairobi.
Figure 19.2
Climograph of a weather station in the Dwd zone, the harshest extreme of the humid
microthermal climate regions.
Figure 19.4
Climograph of a weather station in the Dwa climate zone that also experiences a marked
summer monsoon.
Figure 19.5
Climograph and related graphic displays for a representative weather station in the Dfb
climate zone.
Figure 19.7
Eastern North America weather patterns (A), pollution sources and associated windflows
(B), and land sensitivity related to acid rain occurrence (C).
Figure 19.8
Climograph of a high-latitude tundra (ET) weather station.
Figure 19.9
Climograph and heat balance diagram for a representative weather station in the icecap
(EF) climate zone. There are no precipitation data available for this remote Antarctic
location.
Figure 19.10
A highly generalized west-to-east cross-section of the Andes in equatorial South
America. The vertical climatic zonation shown on the mountain above corresponds to the
Spanish terminology at its right, which is interpreted in the table at the left.
Figure 19.11
From the Fieldnotes: “Watching the sun rise over Kilimanjaro and its ice-capped peak,
Kibo, is one of the most memorable experiences a traveler in East Africa can have, and I
am here as often as I can. In the far distance to the left (east, since we are in Kenya and
viewing from the north) you can see Mawensi, the eroded peak that once looked like Kibo
does today. Up there beyond 5800 m (19,000 feet), the climate is frigid and polar,
although we are within sight of the equator. Two German geographers were the first
Europeans to reach the summits: Hans Meyer climbed Kilimanjaro (5895 m [19,340 ft]) in
1889 and Fritz Klute scaled Mawensi (5,355 m [17,564 ft]) in 1912. Global warming is in
the process of shrinking the permanent ice and snow on Kibo.”
References
Kemp, D. 1990. Global Environmental Issues: A Climatological Approach. New York: Routledge.
UNIT 20
DYNAMICS OF CLIMATE CHANGE
Unit Overview
This unit discusses the concept of climate change through various temporal lenses. The main sections
are:
•
Evidence of climate change
•
The climatic history of the Earth
•
Mechanisms of climate change
•
The climatic future
Climate change is the long-term variability associated with the earth–ocean–climate system. The
variability is caused by changes in certain boundary conditions, such as intensity of sunlight, arrangement
of continents and oceans, and the composition of the atmosphere. Therefore, associated with the
boundary conditions are the mechanisms of climate change. These mechanisms include solar output,
Earth’s’ orbit, continental drift, surface characteristics, and atmospheric particulates, and all those
variables have been changing since Earth’s beginnings. Consequently, Earth has experienced major
changes in climate over the past hundreds, thousands, millions, and billions of years.
Evidence of climate change has been obtained from fossils, sediment cores, ice cores, tree rings,
fossilized pollen, harvest records, and historical narratives. There is no reason to believe that changes in
the Earth’s climate should not happen in the future as well.
Teaching Objectives
•
To examine various lines of evidence for climate change
•
To trace the history of climatic change on Earth, focusing on the past two million years
•
To discuss mechanisms that can cause climatic variations
Lecture Outline
•
Evidence of Climatic Change
o
•
•
•
Evidence of recent climatic variation
The Climate History of the Earth
o
The past 150 years
o
The past 1,500 years
o
The past 15,000 years
o
The past 150,0,000 years
o
The past 1,500,000 years
The Mechanisms of Climate Change
o
External processes
o
Internal processes
The Climatic Future
o
Human interference
Media Resources
Collection of Extreme Weather Data: http://lwf.ncdc.noaa.gov/oa/climate/severeweather/extremes.html
The Canadian Climate Impacts and Adaptation Research Network: http://www.c-ciarn.ca/index_e.asp
David Suzuki Foundation: http://www.davidsuzuki.org/Climate_Change/
Geographical Portal for Climate Change. Learn about the stresses to the atmosphere, potential impacts,
see animations and much more: http://www.geoconnections.org/ccportal/
Photograph Gallery of Weather Extremes: http://photo.weather.com/interact/photogallery/?from=home_dwp
Review Questions
1. What is the Snowball Earth Episode?
2. What was the climate like during the Jurassic?
3. Provide examples of evidence used by scientists to prove climate change occurs.
4. What is one of the main obstacles in efforts to gauge climatic change?
5. When was the most recent cooling trend in Earth’s climate?
6. What is some of the evidence that suggests the Medieval Optimum occurred across the globe?
7. How much ice covered most of Canada during the latest ice age? What was the name of the
latest ice age?
8. How are the Eemian interglacial and the Holocene similar? How are they different?
9. What are the internal and external processes that cause climatic change?
10. Why is it so difficult to predict the future climates of the Earth?
PowerPoint Lecture Guide
First Photo
A glacier melts back as climate warms: you can walk and drive where the Franz Josef
Glacier of New Zealand’s Southern Alps stood less than 50 years ago.
Figure 20.3
The variation of annual mean surface temperatures for the world’s land areas, 18662000. Because this graph incorporates data from many different places, annual mean
temperatures are expressed as a deviation from the average annual mean temperature
for the 1951-1980 period.
Figure 20.4
This graph of surface temperature changes over the past 600,000 years, based on a
composite of seven independent estimates, demonstrates the repeated alternation
between cold and warm conditions.
Figure 20.5
The atmosphere-ocean-ice-Earth climatic system. Red arrows denote external
processes; green arrows indicate internal processes.
Figure 20.7
Long-term changes in the Earth’s orbit and axis: (A) stretch, (B) roll, and (C) wobble.
References
Adams, R.M. 1990. “Global Climate Change and U.S. Agriculture”, Nature, 345 (May 17): 219-224.
Mikolajewicz, D., et. al. 1990. “Ocean Responses to Greenhouse Warming”, Nature, 345 (June 1990):
589-593.
Shukla, L., et. al. 1990. “Amazon Deforestation and Climate Change”, Science, 247 (March 16): 13221325.
White, R.M. 1990. “The Great Climate Debate”, Scientific American, 263 (July 1990): 36-43.
UNIT 21
HUMAN–CLIMATE INTERACTIONS AND IMPACTS
Unit Overview
This unit examines ways in which climate influences human behavior and the impacts of human activities
on the climate. The main sections are
•
Heat balance of the human body
•
Shelter, houses, and climate
•
Urban microclimates
•
Air pollution
•
Human activities and the global climate machine
The human body is a many-systemed organism. One of its systems—heat balance—involves feedback
mechanisms and heat flows. The four major types of heat flows are radiant, metabolic, evaporative, and
convectional. Each flow is affected, either directly or indirectly, by climate.
Climate also plays a part in determining the type of shelter most appropriate (from an energy balance
perspective) for a region. An example of a major disruption of the energy balance at the local scale is the
“urban heat island”, which is characterized by higher temperatures within cities than temperatures in
surrounding rural areas. The high levels of consumption and emission of materials and energy in urban
area, in combination with the nature and the layout of urban surfaces, yields higher temperatures than
would be expected in a less-developed rural area.
Air pollution—a product of the consumption—can disrupt climates and damage sensitive receptors
(including humans). At the mesoscale, winds can distort and advect urban pollution domes, thereby
producing pollution plumes. At the regional scale, winds can transport pollutants hundreds, even
thousands, of miles. Human activities are also sources for greenhouse gases and particulates, both of
which could possibly modify climate at multiple spatial scales. Finally, urbanization and its associated
human activities can modify not only the temperature characteristics of a region but also precipitation
characteristics. In general, urbanization increases precipitation totals in downwind areas.
Teaching Objectives
•
To relate our understanding of atmospheric processes to the human environment
•
To illustrate the utility of using energy balance concepts to characterize systems of the
human environment
•
To focus on several of the impacts humans had, and may come to have, on our climatic
environment
Lecture Outline
•
Heat and Balance of the Human Body
o
•
•

Shortwave radiation

Longwave radiation

Metabolic heat

Sensible heat
Shelter, Houses, and Climate
o
•
Four types of heat flows
Climate effects shelter design
Urban Microclimates
o
Mass, energy, and heat in metropolitan areas
o
Urban heat islands
o
Peculiarities of metropolitan climates
Air Pollution
o
The nature of air pollution
o
Larger-scale air pollution
o
Human activities and the global climate machine
o
Are humans changing the Earth’s climate?
Media Resources
Abstracts from the Canadian Heat Island Summit: http://eetd.lbl.gov/HeatIsland
Data from the NASA/CSA Global Air Pollution Monitor: http://www.gsfc.nasa.gov/gsfc/earth/terra/co.htm
Taking Action on Climate Change: http://www.climatechange.gc.ca
Natural Resources Canada Climate Change Site: http://climatechange.nrcan.gc.ca/
NOW with Bill Moyers. 1/23/04. “Ode to Kyoto”. PBS Home Video.
Alan Alda in Scientific American Frontiers XIV: Hot Times in Alaska. PBS Home Video.
Review Questions
1. What are the four types of heat flow concerning the human body?
2. How is human shelter related to climate?
3. Why is an urban area warmer than the countryside?
4. What are the two ways in which radiant heat from the sun is trapped in a city?
5. What is an urban heat island?
6. What are the requirements for an area to become an urban heat island?
7. What is the heat island intensity?
8. What are primary and secondary pollutants?
9. What is large-scale pollution?
10. What is weather modification? Has is worked?
Possible Assignments
•
There is a strong debate between those who believe that humans are affecting the global
climate and those who believe that humans are not. What is your opinion? Use examples
from the textbook and other sources to back up your answers.
•
Investigate weather modification further. Do you feel humans can change the weather? If so,
is it a step that should be taken? What are the pros and cons?
•
Because of prevailing winds and weather patterns, Atlantic Canada receives much of the
pollution created by Quebec, Southern Ontario and the United States. What is being done to
reduce the pollution? Is there evidence that the pollution is affecting the people of Atlantic
Canada?
PowerPoint Lecture Guide
First Photo
Industries the world over pour pollutants into the atmosphere, affecting global climate. An
industrial complex on the shore of the Inland Sea near Kakogawa, Japan.
Figure 21.1
Heat-energy flows to and from the human body.
Figure 21.2
The limitation imposed on our evaporative cooling system by relative humidity.
Figure 21.3
The adjustment of heat flows under changing environmental temperatures to maintain a
constant internal body temperature.
Figure 21.5
Urban heat island of Montreal, as represented by isotherms of mean late-winter low
temperatures.
Figure 21.6
Wind circulation in an urban dust dome.
Figure 21.7
Average yearly precipitation (in centimetres and inches) in Champaign-Urbana, Illinois.
Figure 21.9
Pollution plume of Mexico City and the surrounding regions. The mages at the far left
and centre are natural colour views acquired by NASA’s Terra satellite on April 9 and
December 5, 2001, respectively. Mexico City can be identified in the centre panel by the
large area of haze accumulation. The right image is an elevation field corresponding to
the December 5 view.
References
There are no additional references for this unit.
UNIT 22
CLIMATE, SOIL, PLANTS AND ANIMALS
Unit Overview
This unit provides an overview of upcoming units by examining the general relationships among climate,
soil, flora, and fauna. The main sections are as follows
•
Natural geography
•
Conservation and the biosphere
Natural geography is the study of soils, plants, and animals from a spatial perspective. Soils exist at the
interface of the lithosphere and the atmosphere, and without water, soil would not exist. When climate,
soils, vegetation, and animal life reach a stable adjustment, vegetation constitutes the most visible
element of the ecosystem.
Teaching Objectives
•
To expand our view of physical geography to include biotic systems operating at the Earth’s
surface
•
To relate biotic systems to our understanding of global climates
•
To link physical geography to the more general topic of conservation
Lecture Outline
•
Natural Geography
o
Geography of soils
o
Biogeography
•
Conservation and the Biosphere
o
Effects of destruction to the environment
o
Earth’s biosphere under stress
o
Wallace’s line
o
Conservation efforts
Media Resources
Explanations of worldwide soil degradation and erosion:
http://royal.okanagan.bc.ca/mpidwirn/agriculture/erosion.html
Baseline data set on all currently known species of plants, animals, fungi and microbes to facilitate global
biodiversity research: http://www.sp2000.org
Atlantic Canadian Conservation Data Centre. Database of information on local Atlantic Canadian species
and ecological communities that are rare or endangered: http://www.accdc.com
Ducks Unlimited Canada. Conserves Canada’s Wetlands: http://www.ducks.ca
Parks Canada. Discover Canada’s Marine Protected Areas and other conservation areas:
http://www.pc.gc.ca
WWF Canada. Conserving wildlife in Canada and around the world: http://www.wwf.ca
Review Questions
1. What is natural geography?
2. What are the two divisions of biogeography?
3. Describe and explain the interface between the lithosphere and atmosphere. What is found
there?
4. Who was Alfred Russsel Wallace and what was his main contribution to biogeography?
5. What is a species?
6. What does conservation entail?
7. Why is biodiversity important?
8. Describe the reasons for the dust bowl.
9. What are some of the conservation strategies in practice in Canada and the United States of
America?
10. What is sustainable development?
Possible Assignments
•
Research and find a plant or animal that is endangered? What are the reasons for the
endangerment? What are the geographical aspects?
•
Find an area that your group believes needs to be conserved and develop a Conservation
Plan to protect it.
PowerPoint Lecture Guide
Figure 22.3
From the Fieldnotes: “About 10m (16 km) from the Kenyan town of Meru the landscape
showed signs of severe erosion. We stopped to talk with the people of these
homesteads, and asked them about their crops. Yes, they knew that farming on slopes
as steep as these would lead to ‘gullying,’ but they saw no alternative. You get a crop one
or two years, and that’s better than nothing, they said. Some neighbours whose village
had lost most of its land this way had gone to the city (Nairobi) we were told, and now the
place where they had lived was like a desert.”
Figure 22.5
Wallace’s Line, the presumed zoogeographic boundary between the faunal assemblages
of Southeast Asia and Australia. One of Wallace’s many challengers, who proposed the
alternative Weber’s Line (see Unit 28), placed that boundary farther to the east.
Figure 22.6
Croplands susceptible to degradation on the basis of climate, soil type, and human
pressures. Such areas are most at risk where population densities are high. That risk is
reduced, however, in countries where proactive measures are being pursued to preserve
soil resources.
Figure 22.8
From the Fieldnotes: “I walked from my hotel toward the main square of the city of
Chengdu. On the opposite side of the square stood a huge billboard. At first I thought that
it was merely an unusually large advertisement (of which one sees rather more in
southern China than in the north in 1981), but soon it became obvious that there was a
message here, and it was clear enough. One child per couple is the official stipulation,
and here that is proclaimed in Chinese as well as English. A tough rule, but it will
undoubtedly be enforced. Perhaps this will slow the land degradation and overuse we
had observed on the way to Chengdu from Kunming.”
Figure 22.10
The region developed by the Tennessee Valley Authority (TVA), beginning in the mid1930s.
References
Gibson, C.W.D., and V.K. Brown. 1985. “Plant succession: theory and applications”, Progress in
Physical Geography 9 (4): 473-493.
UNIT 23
FORMATION OF SOILS
Unit Overview
This unit examines the processes responsible for the formation of soils as well as the general
characteristics of the structural layering of soils. The main sections are as follows
•
The formation of soil
•
Processes in the soil
•
Soil profiles
•
Soil regimes
Soil is comprised of minerals, organic matter, water, and air. Factors involved in the formation of soil
include the parent material, climate, biological agents, topography, and time. Processes acting in the soil
are addition, transformation, depletion, and translocation. These processes are highly variable over space
and over time. Well-developed soils have soil profiles with distinct soil horizons. Each horizon has a
different composition and different properties, which are influenced by processes both within and without
the soil. The interplay of the above factors produces different soils throughout the world, but similar to
climates, soils can be placed into general classes known as soil regimes.
Teaching Objectives
•
To understand the components of soil
•
To outline the factors affecting soil formation
•
To describe and explain a typical soil profile and the processes responsible for the formation
of soil horizons
Lecture Outline
•
The Formation of Soil
o
•
•
•
Factors in the formation of soil
o
Parent material
o
Climate
o
Organisms
o
Topography
o
Time
o
Soil
Process in the Soil
o
Additions
o
Transformations
o
Losses
o
Translocation
Soil Profiles
o
•
Soil components
Soil horizons and Classifications
Soil Regimes
o
3 main regimes
o
Bioclimatic regimes
o

Podzolization regime

Laterization regime

Calcification regime
Hydromorphic regimes

o
Gleization
Geomechanical regimes

Vetisolization regime
Media Resources
An overview of soil formation factors, a description of instruments used to study soil, and a description of
what forensic geologists do: http://ltpwww.gsfc.nasa.gov/globe/forengeo/secret.htm
The Soil Science Society of America: http://www.soils.org
Canadian Society of Soil Science: http://www.csss.ca/
Canadian Journal of Soil Science. Information on this interesting journal: http://pubs.nrc-cnrc.gc.ca/aicjournals/cjss.html
Discovery School – The Dirt on Soil: http://school.discovery.com/schooladventures/soil/
The Soil and Water Conservation Society: http://www.swcs.org/
Life in the Soil. University of Wisconsin-Extension Cooperative Extension: Media Collection. Item Number:
18014. Colour: 30 minutes
Review Questions
1. What is the difference between a renewable and a non-renewable resource?
2. What are the main requirements for soil formation?
3. What is parent material and why is it important?
4. What are two organisms that are important in soil formation? What are their roles?
5. What are the four processes of soil?
6. What is a soil horizon?
7. What are the definitions of each letter in the soil classification scheme?
8. What are the three main types of soil regimes and their divisions?
9. What are the main differences between the different soil regimes?
10. Explain the exchange of cations.
Possible Assignments
•
What type of soil do you believe would most likely be found in your area? Why?
•
What are the types of soil in each group members’ home area? Are they similar to the type of
soil found around your school? Find an appropriate place as a sample area and take a
sample of soil. Can our group identify the changes in soil types?
PowerPoint Lecture Guide
First Photo
Massive, destructive erosion in the tropical rainforest of southeastern Nigeria. This
erosional scar is largely the result of local misuse of the land.
Figure 23.1
From the Fieldnotes: “Driving upcountry from Colombo to Kandy in Sri Lanka, you see
areas where the whole countryside is transformed by human hand into intricate,
meticulously maintained terraces. It is the product of centuries of manipulation and
maintenance, with long-term success depending on careful adjustment to nature’s cycles
and variations. Scenes like this (and similar ones can be observed in Indonesia, the
Philippines, and other rice-growing societies) reflect a harmonious human-environment
relationship evolved over countless generations.”
Figure 23.2
From the Fieldnotes: “My first field experience in one of China’s Autonomous Regions,
the Guangxi-Zhuang A.R., designated for non-Han minorities, had mixed results. Land
degradation here was more advanced than in any other part of China visite;
desertification seemed to be in progress in many areas. The cause, overuse of land, and
the collapse of what appeared to have been sound terracing systems. My Chinese
colleague told me that China’s rules for population control and land use were relaxed in
these Autonomous regions, often leading to ecological damage.”
Figure 23.3
The four major components and their relative positions within a tiny clump of soil.
Figure 23.5
A soil profile, typical of the humid midlatitudes, showing the various soil horizons.
Figure 23.6
The stages of soil horizon evolution on a sedimentary parent material.
References
There are no additional references for this unit.
UNIT 24
PHYSICAL PROPERTIES OF SOIL
Unit Overview
This unit examines the different physical properties of soil. These properties vary over space and time.
The main sections are as follows:
•
Sol and ped
•
Soil texture
•
Soil structure
•
Soil colour
•
Soil acidity and alkalinity
•
Soils of hills and valleys
•
The soil-development system
“Sol” and “ped” are two common terms encountered when studying soils. Texture, which includes the size
of the particles in the soil, alters the porosity and permeability. For example, a “clay” soil has a low
permeability.
Regarding structure, a soil can have either a platy, prismatic, blocky/angular, or spheroidal/granular
structure. The structure can greatly affect a soil’s resistance to erosion. Soils can also have a range of
different colours. The acidity of a soil is controlled by the presence of hydrogen, and the acidity, in turn,
affects the fertility of soils. In addition, topography plays a large role in soil formation. Finally, the soildevelopment process results in soils composed of the following ingredients: organic matter, resistant
residue (often silica, such as quartz particles), altered chemical compounds, and soil solution.
Teaching Objectives
•
To introduce terminology used to describe soil characteristics
•
To define some important properties that result from a soil’s physical characteristics
•
To illustrate the likely arrangement of soil characteristics in a hypothetical landscape
Lecture Outline
•
•
•
•
Sol and Ped
o
The solum
o
The pedon
Soil Texture
o
Sand
o
Silt
o
Clay
o
Loam
o
Field capacity
Soil Structure
o
Platy structure
o
Prismatic structure
o
Blocky (or angular) structure
o
Spheroidal (or granular) structure
o
Soil consistence
Soil Colour
o
•
•
Different colours indicate different types of materials
Soil Acidity and Alkalinity
o
PH
o
Importance of acidity for nutrients
Soils of Hills and Valleys
o
•
Importance of topography
The Soil-Development System
o
Organic matter
o
Resistant residue
o
Altered chemical compounds
o
Soil solution
Media Resources
International Fertilizer Industry Association’s Homepage: http://www.fertilizer.org
Physical Properties of Soil. Use this interactive flash animation from the University of North Carolina to
determine the soil classification: http://serc.carleton.edu/introgeo/field_lab/examples/soils.html
Soil Structure: http://ltpwww.gsfc.nasa.gov/globe/pvg/prop1.htm
Soil Science. Links to everything you want to know about soil:
http://www.stormloader.com/geocoop/soils.htm
Deadly Fields. University of Wisconsin-Extension Cooperative Extension: Media Collection. Item Number:
18007. Colour: 58 Minutes.
Review Questions
1. What is the solum and where is it found?
2. What is the pedon? What is a ped?
3. Why is texture important? What does it tell you?
4. What is loam? What is a soil’s field capacity?
5. What are the four basic structures that soils exhibit?
6. What is soil condidtence?
7. Why is soil colour important? What can it tell you about soil?
8. Why is acidity important in soil? What problems are associated with soils that are too acidic or
too alkaline?
9. Why does topography have an effect on soil?
10. What are the four inputs (ingredients) in the soil system?
Possible Assignments
•
What is the topography like in your area? Is its affect on the soil apparent?
PowerPoint Lecture Guide
First Photo
Fertile luvisols in the agriculturally productive Paris Basin.
Figure 24.1
A complete soil column or pedon.
Figure 24.2
Soil texture categories, defined by the percentages of sand, silt, and clay found in a soil
sample.
Figure 24.7
A type of soil catena commonly found in southern Sudan.
Figure 24.8
The structure and flows of the soil-development system.
References
Guo, X., et al. 2001. “Spatio-temporal variability of soil nutrients in the Zunhua plain, Northern China”,
Physical Geography, 22(4): 343-360.
Schaetzl, RJ., and S.A. Isard. 1991. “The distribution of Spodosol soils in southern Michigan: a climatic
interpretation”, Annals of the Association of American Geographers, 81(3): 425-442.
UNIT 25
CLASSIFICATION AND MAPPING OF SOILS
Unit Overview
This unit describes the soil orders. The main sections are as follows:
•
Classifying soils
•
The soil orders
•
The spatial distribution of soils
Soils are complex entities because the same parent materials develop differently under different
environmental conditions. However, soils are not classified genetically. Instead, soils are classified based
on their actual, present-day characteristics.
The current Soil Taxonomy has twelve soil orders. They are entisols, histosols, vertisols, inceptisols,
gelisols, andisols, aridisols, mollisols, alfisols, spodosols, ultisols, and oxisols. A soil order is a general
grouping of soils with broadly similar compositions, the presence or absence of specific diagnostic
horizons, and similar degrees of horizon development, weathering, and leaching.
Teaching Objectives
•
To present a brief history of soil science and highlight problems in achieving a universal soil
classification scheme
•
To outline the current Canadian system of soil classification
•
To outline the current U.S. Soil Taxonomy
•
To survey the 12 Soil Orders in the CSSC and examine their regional patterns on the North
American and world map
Lecture Outline
•
•
Classifying Soils
o
Overview of soil classification in Canada and the U.S.
o
Marbut and his soil types (pedocal and pedalfer)
o
The U.S. Soil Taxonomy
o
Canadian System of Soil Classification
o
Soil classification on a hypothetical continent
The Soil Orders
o
Brunisolic Order (Inceptisols)
o
Chernozemic Order (Mollisols)
o
Cyrosolic Order (Gelisols)
o
Gleysolic Order (No U.S. Equivalent at Order Level—but Equivalent to Aquic Suborders)
o
Luvisolic Order (Alfisols)
o
Organic Order (Histosols)
o
Pdzolic Order (Spodosols)
o
Regosolic Order (Entisols)
o
Solonetzic Order (No U.S. Equivalent Order – Natric Suborders of Mollisols, Alfisols and
Aridisls)
o
•
Vertisolic Order (Vertisols)
The Spatial Distribution of Soils
o
Soils of North America
o
Topography and climate
o
The world soil map
Media Resources
Current Canadian System of Soil Classification: http://sis.agr.gc.ca/cansis/taxa/cssc3
A compendium of online soil information, compiled by D.G. Rossiter:
http://www.itc.nl/~rossiter/research/rsrch_ss_class.html
The USDA-NRCS National Soil Survey has the second edition of Soil Taxonomy, A Basic System for Soil
Classification for Making and Interpreting Soil Survey available for download from this site:
http://soils.usda.gov/technical/classification/taxonomy/
Review Questions
1. Who was Marbut? What was his soil classification system? What were some of the major flaws of
the system?
2. What are the main differences between the Canadian and American classification systems?
3. How is soil distribution on a hypothetical continent related to the climate distribition on a
hypothetical continent?
4. How many soil orders are there? What are their names?
5. What are the differences between Brunisolic Order soils and Cryosolic Order soils?
6. What are the differences between Organic Order soils and Podzolic Order soils?
7. Why does climate not play a large role in the distribution of Regosolic Order soils?
8. Which soil order(s) are low in organic carbon?
9. What is the largest problem for humans associated with Vertisolic Order soils?
10. Why do similar climates not always correspond to similar soil types?
Possible Assignments
•
Read “Perspectives on the Human Environment, Soil Taxonomy – What’s in a Name?” on
page 321. Which classification naming system do you feel is more appropriate, the Canadian
system using Russian words or the American system deriving words from Latin and Greek?
Why do you feel this way?
•
Develop a hypothetical continent and map the soils that would likely be found in the different
areas.
PowerPoint Lecture Guide
First Photo
Diagnostic properties of soil form the basis of regional classification: drought-affected
vertisol near Baotou, China.
Figure 25.1
The Soils of Canada and the United States, divided into two major classes determined by
climate (after Marbut).
Figure 25. 12
Primary relationships among the five spheres of the Earth System and the Soil Orders of
the Canadian System of Soil Classification (the U.s. Soil Orders are in parentheses).
Figure 25.13
From the Fieldnotes: “What should have been one day in Suva, the capital of Fiji, turned
into a week due to schedule complications, and we had an opportunity to study Viti
Levu’s interesting human as well as physical geography. Driving through the interior was
challenging because maps and reality seemed to differ; but homesteads and villages
were interesting and welcoming. The island has some fertile soils, but much of the center
was dominated by oxisols which, when fully developed, are deep (often dozens of
metres) and characteristically red-coloured due to the preponderance of iron and
aluminum in the oxic horizon. The upper part of this profile of a local oxisol shows the
virtual absence of humus in these soils; note also the virtual absence of colour change
from very near the top of the soil all the way down.”
Figure 25.14
Profile of red-yellow podzolic (ultisol), exhibiting a B-horizon rich in clay.
Figure 25.15
Generalized spatial distribution of soils in North America using the Canadian Soil Orders
(U.S. Soil Orders are in parentheses).
References
Campbell, B., and W.J. Edmunds. 1984. “The missing geographic dimension of ‘Soil Taxonomy’”, Annals
of the Association of American Geographers, 74(1): 83-97.
Phillips, D. 2001. “The relative importance of intrinsic and extrinsic factors in pedodiversity”, Annals of the
Association of American Geographers, 91(4): 609-621.
UNIT 26
BIOGEOGRAPHIC PROCESSES
Unit Overview
This unit examines processes that occur within the biosphere. The main sections are as follows:
•
Dynamics of the biosphere
•
Plant successions
•
Geographic dispersal
The dynamics of the biosphere involve photosynthesis and the subsequent flow of energy within the
ecosystems. An ecosystem is a linkage of organisms to their environment. The initial suppliers of the
energy are organisms known as autotrophs. Herbivores and carnivores transfer energy. Major changes
within ecosystems occur as a result of plant successions, which are initiated by internal and external
agents.
Limiting factors in two main categories controls the distribution of plants on the Earth’s surface: physical
and biotic. The physical factors include temperature, the availability of water, the availability of light, wind,
snow cover, the distribution of soils, and landforms. The biotic factors include competition, amensalism,
predation, mutualism, and endemism. As can be discerned from above, complex processes involving
numerous factors control the assemblage of plants in any given location.
Teaching Objectives
•
To discuss the process of photosynthesis and relate it to climate controls
•
To introduce the concept of ecosystems and highlight the important energy flows within
ecosystems
•
To outline the factors influencing the geographic dispersal of plant and animal species within
the biosphere
Lecture Outline
•
•
•
Dynamics of the Biosphere
o
Photosynthesis
o
Limitations of photosynthesis
o
Phytomass
o
Ecosystems and Energy Flows
o
Ecological efficiency
Plant Successions
o
Linear autogenic succession
o
Cyclic autogenic succession
o
Allogenic succession
Geographical Dispersal
o
o
Physical Factors

Temperature

Availability of water

Other climatic factors

Distributions of solis

Landforms
Biotic Factors

Competition

Anensalism

Predation

Mutualism

Species dispersal and endemism
Media Resources
Review of Photosynthesis: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html#
What%20is%20Photosynthesis?
Australia and New Zealand Rabbit Calcivirus Disease Program (wants to reduce the rabbit population):
http://http://www.csiro.au/communication/rabbits/rabbits.htm
Information about Canadian Tree Species: http://www.canadianbiodiversity.mcgill.ca/english/species/
Information and images for the World’s land-based ecoregions. Also available is data from Project Global
2000: Priority areas for ecological conservation: http://www.nationalgeographic.com/wildworld
Agriculture Canada Lethbridge Research Institute: http://res2.agr.ca/lethbridge/index_e.htm
Plant Succession: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Succession.html
Links to everything you want to know about photosynthesis:
http://photoscience.la.asu.edu/photosyn/education/learn.html
Last Stand of the Tall Grass Prairie. PBS Home Video.
Review Questions
1. Describe photosynthesis
2. What are the limiting factors of photosynthesis?
3. What is an ecosystem?
4. What is a trophic level?
5. What are the three types of plant succession? What are the differences between the types?
6. What is a climax community?
7. What are the physical factors causing geographic dispersal?
8. Study and explain Figure 26.8.
9. What are the biotic factors causing geographic dispersal?
10. What is the species-richness gradient?
Possible Assignments
•
Study Figure 26.14. Is there a “hot spot” near your area? If so, what are some of the
programs in place to help the threatened species? If not, pick “hot spot” and investigate
mitigation techniques in that area.
PowerPoint Lecture Guide
First Photo
Death and life in the African savanna: vultures on an elephant carcass in Tsavo West,
Kenya.
Figure 26.1
The development of the biosphere on Earth: the time scale of life.
Figure 26.3
The global distribution of annual biomass productivity (in grams per square metre of dry
biomass matter).
Figure 26.4
From the Fieldnotes: “A pond like this is a crucial part of the local ecosystem. The sun’s
energy reaches the surface of this lake in Britian’s Lake Country, where phytoplankton
(microscopic green plants) convert it through photosynthesis into carbohydrate, a food
substance. Tiny life forms, zooplankton, feed on this carbohydrate, and small fish eat the
zooplankton. Larger fish feed on the smaller fish, and the food chain continues.”
Figure 26.5
Mass of living materials per unit of area in different trophic levels of an ecosystem.
Figure 26.6
An idealized sequence of a linear autogenic plant succession by which a lake is
eventually colonized by shrubs and trees.
Figure 26.7
The increase in stored energy of the biomass in a typical secondary autogenic
succession. In this case, a deciduous hardwood forest takes over from an abandoned
field over a period lasting about 175 years.
Figure 26.8
A model of population abundance in relation to the physical factors in the environment of
a species.
Figure 26.9
Zones of vegetation and animal life on the flanks of Mount Kenya in East Africa, which
lies directly on the Equator.
Figure 26.13
From the Fieldnotes: “Along the northern California coast, you can see the competition
between sagebrush and grass in progress, the grass losing out over time. The
Mediterranean climatic regime, high relief, and thin soils give the better-adapted sage a
durable advantage.”
Figure 26.14
The global distribution of biodiversity “hot spots.” These areas contain high
concentrations of endemic species that are threatened by human activities.
References
Walker, R.T., and W.D. Solecki. 1999. “Managing land use and land-cover change: The New Jersey
Pinelands biosphere reserve”, Annals of the Association of American Geographers, 89(2): 220-237.
UNIT 27
THE GLOBAL DISTRIBUTION OF PLANTS
Unit Overview
This unit examines the distribution of plants across the Earth’s continents by focusing on biomes. The
main sections are as follows:
•
Biomes
•
Principal terrestrial biomes
A biome is the broadest justifiable subdivision of the plant and animal worlds. It is an ecological unit that is
present at the sub-continental scale. The location of a biome is controlled by air masses, solar radiation,
topography, and the distribution of landmasses and oceans.
The principal terrestrial biomes are tropical rainforest, tropical savanna, desert, temperate grassland,
temperate forest, Mediterranean Scrub, northern coniferous forest, and tundra. As a result of its many
variations in air masses, solar radiation, topography, a continent such as North America contains many of
these biomes.
Teaching Objectives
•
To briefly survey the principal terrestrial biomes
Lecture Outline
•
Biomes
•
o
What is a biome?
o
Where are different biomes located in North America
Principal Terrestrial Biomes
o
Tropical rainforest
o
Tropical savanna
o
Desert
o
Temperate grassland
o
Temperate forest
o
Mediterranean scrub (Sclerophililus forest)
o
Northern coniferous forest
o
Tundra
Media Resources
Biogeography Specialty Group of the American Association of Geographers:
http://www.geocities.com/RainForest/2498/bsghome1.htm
Information regarding each of the world’s biomes: http://www.worldbiomes.com
The distribution of plants over the Earth. Quick information about the distribution of plants:
http://www.plant-talk.org/Pages/Pfacts2.html
The World’s Biomes from the University of Berkeley: http://www.ucmp.berkeley.edu/glossary/gloss5/biome/
Biomes of the World: http://ridge.icu.ac.jp/gen-ed/biomes.html
Invasive Species. A paper about the invasive species in Richmond, B.C.:
http://www.geog.ubc.ca/richmond/city/vasiveplants.htm
Invasive plants of natural habitats in Canada: an integrated review of wetland and upland species and
legislation governing their control: http://www.cws-scf.ec.gc.ca/publications/inv/index_e.cfm
Review Questions
1. What is a biome?
2. What are the different vegetation regions in North America? Explain the reasons for their
locations.
3. How are changes and elevation and changes in latitude related in terms of biomes? What
4. What is a tree line?
5. What are the principal terrestrial biomes?
6. Explain the differences between the Tropical Savanna biome and the temperate grassland biome.
7. Where is the desert biome most likely to be found?
8. What are the two main types of Temperate Forest biomes?
9. Why is the Mediterranean Scrub biome misleading?
10. The Tropical Rainforest biome is found near the equator, while the Tundra biome is found near
the poles. Explain the differences between the two biomes. Do they have any similarities?
Possible Assignments
•
Choose one biome and research it extensively. How do humans cope within this biome?
Have humans altered the landscape a great deal? What animals are found there? What
plants?
PowerPoint Lecture Guide
First Photo
Montane forest in East Africa’s Chyulu Hills, where elevation and moisture combine to
sustain luxuriant flora amid steppe and savanna.
Figure 27.1
Global distribution of the principal terrestrial biomes.
Figure 27.2
Distribution of natural vegetation in North America.
Figure 27.3
Vegetation changes with latitude and altitude. Temperature, which affects vegetation,
decreases as one travels up a mountain or away from the Equator, so that if there is
plenty of moisture, vegetation is similar at high altitudes and at high latitudes, as shown
here.
Figure 27.4
Simplified scheme of the major terrestrial biomes, arranged along gradients of increasing
aridity at different latitudes, illustrating the dominant influence of moisture and
temperature on the structure of plant communities.
Figure 27.5
From the Fieldnotes: “The East African savanna is sometimes called a ‘parkland’
savanna because trees are widely spaced and give the landscape a regularity that seems
cultivated, not wild. The umbrella-like acacia tree is an ally of wildlife and human traveler
alike, as I can attest - its shade made many a hot day bearable. The savanna feeds
grazing animals as well as browsers because it offers grasses as well as leaves to its
migrant]; the flat-topped acacia tends to be trimmed at around 5 m (17 ft) by giraffes,
which are able to strip leaves from the thorniest of branches. And, as this photo shows,
the Acacia supports other species as well, as the large and occupied eagle’s nest
confirms.”
Figure 27.6
From the Fieldnotes: “A field trip through Arizona desert country reminded us that the
desert biome encompasses rich and diversified vegetation. Despite the often thin and
unproductive aridisols prevailing under desert climatic conditions, the infrequent and
scant rainfall recorded here is enough to sustain a wide range of plant species as well as
a varied fauna.”
Figure 27.10
From the Fieldnotes: “Mediterranean physical and cultural landscapes coexist in a
distinctive way. Where human activity has encroached onto even the steepest slopes,
Mediterranean vegetation somehow survives. Italy’s Amalfi coast, south of Naples,
provides an example.”
References
Bowman, D.L. 1994. “Tropical rain forests”, Progress in Physical Geography, 18(4): 575-581.
Gibson, C.W.D., and V.K. Brown. 1985. “Plant succession: theory and applications”, Progress in Physical
Geography 9(4): 473-493.
UNIT 28
ZOOGEOGRAPHY: SPATIAL ASPECTS OF ANIMAL POPULATIONS
Unit Overview
This unit examines the spatial distribution of fauna on Earth. The main sections are as follows:
•
Processes of evolution
•
Emergence of zoogeography
•
The Earth’s zoogeographic realms
•
Further studies in zoogeography
•
Zoogeography and conservation
A species’s habitat is the environment it normally occupies within its geographic range. Species evolve to
adapt optimally to the habitat, and as habitats change, species must change, move, or die. Species
change through the process of evolution, which involves the mutation of genes. Therefore, the location of
habitats and the characteristics of species within them are always changing.
One can generalize the distribution of fauna on the Earth’s surface by considering zoogeographic realms.
These realms contain different habitats, which, in turn, contain multiple ecological niches. Because
humans can alter a habitat, we are capable of dramatic effects on the increases and decreases of
animals in a specific habitat.
Teaching Objectives
•
To briefly outline the theory of evolution and related principles such as natural selection,
which led to the present-day spatial distribution of animals
•
To give a brief history of zoogeography
•
To relate zoogeography to the larger context of environmental conservation
Lecture Outline
•
•
•
•
Process of Evolution
o
Evolution
o
Mutation
o
Ecological Niche
o
Habitat
Emergence of Zoogeography
o
Alexander Von Humbolt
o
Charles Darwin
o
Wallace’s Line
The Earth’s Zoogeographical Realms
o
Nearctic
o
Neotropical
o
Pacific
o
Palaearctic
o
Palaeotropical (Ethiopian)
o
Indomalayan (Oriental)
o
Madagascan
o
Australian
o
New Zealand
o
Antarctic
Further Studies in Zoogeography
o
•
Island zoogeography
Zoogeography and Conservation
o
Animal Ranges
o
Human Impact on Animal Habitats
o
Preservation Efforts
Media Resources
Evolution: http://www.pbs.org/wgbh/evolution/
A page of wildlife conservation links: http://animals.about.com/cs/conservation
Authoritative website about the ungulates of the world: http://www.ultimateungulate.com/
Species at Risk in Canada: http://www.hww.ca/hww2.asp?cid=4&id=232
Review Questions
1. Explain the processes of evolution.
2. What is an ecological niche?
3. Who were Alexander von Humbolt and Charles Darwin? What were their contributions to
zoogeography?
4. Provide examples of animals that have evolved a particular way for a particular purpose.
5. What are the world’s ten zoogeographical realms?
6. What are the four questions posed by Darlington to zoogeographers?
7. What is island zoogeography?
8. What aspect of larger islands impacts the amount of species found on the island?
9. Why is it important to understand the numbers, ranges, habits and reproductive success of
different animals?
10. What problems can occur when species from one continent or biome spread into another?
Possible Assignments
•
Madagascar has a distinct zoogeographic realm. Research the literature on this country and
its zoogeographic realm. Why do you believe that its zoogeographic realm is so different from
that of nearby East Africa?
•
What do you feel would be the greatest challenges in setting up preservation or protective
areas for a animal that crosses international boundaries because of migration patterns?
PowerPoint Lecture Guide
First Photo
The vast Serengeti Plain is one of Africa’s most extensive and effective wildlife refuges.
Zebra, wildebeest, topi, and other herbivores still number in the millions.
Figure 28.1
From the Fieldnotes: “Safari in Tanzania, March 1984. Spent a morning watching a small
herd of giraffes as they browsed together, dispersed in the bush, reconvened, were
briefly joined by a small herd of zebras, and then separated again. In the competitive
evolution of East Africa’s herbivores, these longer-necked animals had advantages,
notably their access to food beyond the reach of others, that led to larger numbers of
offspring - who passed the genetic information involving the long neck to later
generations.”
Figure 28.2
From the Fieldnotes: “Moving slowly and quietly through a eucalyptus forest in New
South Wales, Australia I was rewarded with this extraordinary sight, a koala resting in a
tangle of branches. The koala “bear” is part of Australia’s unique fauna; it is a marsupial
and carries its offspring in its pouch for as long as seven months. It eats about 1.3 kg (3
pounds) of eucalyptus leaves daily, but only a particular kind and quality of leaf; in the
wild its life span averages 20 years. The koala has diminished in number from an
estimated several million to perhaps 150,000, and the population continues to decline as
humans encroach on its natural habitat and diseases take their toll.”
Figure 28.3
Wallace’s Line across the Indonesian archipelago. This controversial boundary between
the faunal assemblages of Southeast Asia and Australia was challenged by Max Weber,
who placed his alternative Weber’s Line much closer to Australia and New Guinea.
Figure 28.4
World zoogeographic realms.
Figure 28.5
From the Fieldnotes: “We drove across an expanse of lava formed from a recent fissure
eruption in Tanzania - so recent that virtually no vegetation had yet taken hold on it.
Research has shown that plant manage to establish themselves quite soon (a matter of
years, not generations or centuries) after new rocks are created by volcanic eruptions.
This lava must therefore be quite young, but the process is clearly at work. A seed found
a way to sprout in a crack in the rock, where weathered particles and some moisture
supplied the essentials for growth.”
Figure 28.6
Ranges of some North American mammals.
Figure 28.7
From the Fieldnotes: “Safari, Tanzania, February 1989. A herd of buffalo stops at a small
waterhole in Manyara National Park. The rift valley wall that marks the western limit of the
Lake Manyara Rift is in the background; if the photographer turned around, Lake
Manyara would be visible. The park constitutes a narrow strip of land, but it has a rich
fauna. Such richness of animal life prevailed across much of tropical Africa before the
arrival of the European colonialists, who upset the long-established balance among
indigenous peoples, their livestock, and the realm’s wildlife. Hunting for “sport” was not
an African custom; neither was killing for fashion.”
References
Gillespie, T.W. 2001. “Remote sensing of animals”, Progress in Physical Geography, 25(3): 355-362.
UNIT 29
PLANET EARTH IN PROFILE: THE LAYERED INTERIOR
Unit Overview
This unit examines the Earth’s lithosphere and its context. The main sections are as follows:
•
Evidence of the Earth’s internal structuring
•
The Earth’s internal layers
•
The Earth’s outer layer
•
The crustal surface
Seismic waves have provided scientists with clues about the Earth’s internal structuring and composition.
The internal layers consist of the solid inner core, the liquid outer core, the solid lower mantle, and the
upper mantle.
The lithosphere is part of the Earth’s outer layer and is comprised of the crust and the solid part of the
upper mantle. The crustal surface has varying degrees of topographic relief; the continental shield (low
relief) and orogenic belts (high relief) represent two extremes in relief. The atmosphere, biosphere,
hydrosphere and cryosphere are responsible for gradational processes that wear away the lithosphere.
Teaching Objectives
•
To outline the relevant properties of the Earth’s five internal layers and to discuss some of the
evidence leading to their discovery
•
To introduce the salient properties of the Earth’s lithosphere, the nature of the crust, and the
underlying mantle
•
To investigate the gradational processes that continually build as well as remove rock
material at the Earth’s surface, creating physical landscapes of great diversity
Lecture Outline
•
•
•
•
Evidence of the Earth’s Internal Structure
o
Earthquakes
o
Types of seismic waves
The Earth’s Internal Layers
o
P-waves
o
S- waves
o
Solid inner core
o
Liquid outer core
o
Solid lower mantle
o
Upper mantle
The Earth’s Outer Layer
o
Structural properties of the crust
o
The lithosphere
o
Lithospheric plates
The Crustal Surface
o
Topographical relief
o
Continental shields
o
Orogenic belts
o
Gradational processes
Media Resources
Earth’s Interior: http://www.seismo.unr.edu/ftp/pub/louie/class/100/interior.html
Site for the International Drilling Program: http://www.iodp.org
Website for the Lithoprobe project: http://www.lithoprobe.ca
Earthquakes Canada: http://www.seismo.nrcan.gc.ca
Review Questions
1. What evidence suggests the concept of an internally layered earth?
2. What are P–Waves? What are S–Waves?
3. What are the internal layers of the Earth?
4. What is the lithosphere?
5. What is the Mohorovicic discontinuity?
6. How are Oceanic crust and Continental crust similar? How are they different?
7. What is topographic relief?
8. What is a continental shield?
9. What is an orogenic belt?
10. What is a gradational process?
Possible Assignments
•
Construct your own diagram of the internal layers of the earth. Be sure to properly label and
provide information on all of the layers.
•
Pick two different mountain ranges created at different time periods (ie: the Appalachians and
the Rockies) and compare and contrast their similarities and differences.
PowerPoint Lecture Guide
First Photo
A glimpse of the interior; gases emanate from the layered walls of a collapsed volcano
island of Hawai’i.
Figure 29.2
When seismic waves travel through the interior of the Earth, several things happen.
When they reach a plane where the rock material becomes much denser, they may be
reflected back (A). If the contrast in rock density is less, they may be refracted (B). Their
velocities are also affected. Speeds would be less in the layers marked X and greater in
layer Y.
Figure 29.3
Imagine that a strong earthquake occurs at the North Pole (zero degrees on the drawing).
This diagram shows the paths of the radiating P, S, and L waves as they travel through
the planet. Note that no P waves are received over a large shadow zone in the Southern
Hemisphere, between 103 and approximately 142 degrees from the quake’s source at
zero degrees. This allows us to identify the depth at which the solid mantle yields to the
liquid outer core. From the refraction of the P waves, we can deduce the contrast in
density between mantle and outer core materials.
Figure 29.4
Certain P waves are reflected back toward the crust when they reach the outer edge of
the solid inner core. From their travel times, the position of the contact between solid
inner core and liquid outer core can be deduced. Note: the refraction of these waves, as
they traverse the interior of the Earth, is not shown.
Figure 29.5
The principal layers of the inner Earth.
Figure 29.6
The Mohorovicic discontinuity (Moho) marks the base of continental as well as oceanic
crust. As the sketch shows, it lies much closer to the crust’s surface under the oceans
than beneath the land.
Figure 29.7
A and B From the Fieldnotes: “Baking in the African sun is some of the Earth’s oldest
rock: ancient granite, sialic, light-weight continental rock that has been part of the African
shield for 3 billion years (A). Whenever you travel across the African landscape, you note
how light-coloured these crystallines are, coloured white, beige, or pink according to their
composition (dominant quartz creates the lightest colour; feldspars form light shades of
red). But when new rock emerges from the Earth’s interior, as on Pacific islands or along
mid-ocean ridges, it is dominated by basalt, dark-coloured, and heavier (B). This is young
sima, and it constitutes the ocean floors.”
Figure 29.8
The position of the asthenosphere in the Earth’s mantle. The boundary between the
asthenosphere and the lithosphere is a transition zone rather than a sharp divide. Its
depth beneath the surface is about twice as great under the continents as under the
oceans.
Figure 29.11
Continental shields of the world, representing materials that cooled from the earliest
molten surface or after the impact of meteorites early in the geological history of the
Earth.
References
There are no additional references for this unit.
UNIT 30
MINERALS AND IGNEOUS ROCKS
Unit Overview
This unit examines minerals (the building blocks of rocks) and the primary rock type, igneous rocks. The
main sections are as follows:
•
Minerals and rocks
•
Classification of rock types
•
Igneous rocks
A mineral is a naturally occurring inorganic element or compound having a definite chemical composition,
physical properties, and usually, a crystalline structure. Approximately 100 different types of minerals can
be identified based on their chemical composition, hardness, cleavage/fracture, colour/streak, and luster.
Rocks are comprised of mineral assemblages, and the three types of rocks are igneous, sedimentary,
and metamorphic. Igneous rocks form first (i.e. they are primary rocks), and they consist of intrusive and
extrusive forms. Jointing and exfoliation of igneous rocks facilitates their weathering and subsequent
erosion. This wearing away of igneous rocks produces material that can be incorporated into sedimentary
rocks.
Teaching Objectives
•
To understand the relationship between rocks and their constituent minerals
•
To briefly investigate the important properties of minerals and to provide an elementary
scheme for their classification
•
To discuss some important aspects of igneous rocks and their influence on landscape form
Lecture Outline
•
Minerals and Rocks
o
•
•
•
•
What are minerals?
Mineral Properties
o
Chemical composition
o
Hardness
o
Cleavage/fracture
o
Colour/streak
o
Lustre
Mineral Types
o
Silicates and non-silicates
o
Carbonates
o
Sulphates
o
Sulphides
o
Halides
o
Oxides
Classification of Rock Types
o
Magma
o
Igneous rocks
o
Sedimentary rocks
o
Metamorphic rocks
Igneous Rocks
o
Intrusive forms
o
Jointing and exfoliation
o
Igneous rocks in the landscape
Media Resources
The Atlas of Canada – Major Rock Categories:
http://atlas.gc.ca/site/english/maps/environment/geology/majorrockcategories/1
A Guide to Igneous Rocks and their Classification: http://csmres.jmu.edu/geollab/Fichter/IgnRx/Ighome.html
Background information on rock formation and structure from an Australian Earth science site:
http://earthsci.org/rockmin/rockmin.html
Information about minerals and links to relevant sites: http://www.mineralogicalassociation.ca/
Canadian Museum of Nature: http://www.nature.ca/
Web page about the Royal Ontario Museum acquiring the Charles Key Mineral Collection:
http://www.rom.on.ca/news/releases/public.php?mediakey=bno3zng93n
Organization of the Igneous Rocks Site: http://csmres.jmu.edu/geollab/Fichter/IgnRx/Ighome.html
Review Questions
1. What is the difference between minerals and rocks?
2. What are the five different properties of minerals?
3. What is crystalline?
4. List the six natural elements
5. What is the most easily observable property of a mineral? Describe this property.
6. Describe the two different elements as to how the Earth developed its core.
7. What is the difference between intrusive and extrusive igneous rocks?
8. Describe the differences between jointing and exfoliation.
9. Explain magma and lava.
10. What is etchplanation?
Possible Assignments
•
Provide rock samples for the students to study. Use samples with different hardness,
cleavage/ fracture, colour/streak, and luster. Have the students study and compare each
sample.
PowerPoint Lecture Guide
First Photo
A quartz vein invaded this crystalline bedrock millions of years ago, filling a joint plane
and cementing the stock. Now exposed and dilated, it forms a point of weakness as
weathering and erosion attack.
Figure 30.4
Diagrammatic cross-section through the uppermost crust that shows the various forms
assumed by plutons.
Figure 30.5
From the Fieldnotes: “With a faculty member of the University of Tasmania’s Department
of Geography we drove from Hobart, the capital, to Port Arthur, the former penal colony.
The Tasman Peninsula presents numerous sites of physical-geographic interest,
including this wave-cut platform, where marine erosion has exploited joints in igneous
rock. The joint pattern now looks like a roughly tiled floor, planed down by waves rolling
over it and exposed by subsequent uplift. At high tide, waves still wash over the platform,
filling the joint planes and enhancing the pattern.”
Figure 30.6
From the Fieldnotes: “The cable-car ride to the top of Sugar Loaf Mountain in the heart of
Rio de Janeiro, Brazil provided a dramatic vista over this massive city’s unique and
scenic site. Great granite stocks and batholiths, formed deep below the surface and
exposed by uplift and erosion, now create towering domes among which the city’s
structures are nestled. As erosion removed the overburden, the release of weight on
these domes resulted in exfoliation. The outer shells peeled off, leaving rounded, often
smooth-surfaced landforms rising above the countryside.”
References
There are no additional references for this unit.
UNIT 31
SEDIMENTARY AND METAMORPHIC ROCKS
Unit Overview
This unit examines the two secondary rock types, sedimentary and metamorphic rocks. The main
sections are as follows:
•
Sedimentary rocks
•
Metamorphic rocks
•
The rock cycle
Sedimentary rock results from the deposition and compaction of rock fragments and mineral grains
derived from other rocks. Physical and chemical weathering and the subsequent erosion of the weathered
material precede the lithification process. Pressure lithifies the sediment while the cementation of grains
by silica and calcite begins.
Sedimentary rocks include clastic and nonclastic subtypes. Clastic rocks range in grain size from shale to
conglomerates. The layering of rocks is known as stratification. The presence of entities within and
between sedimentary rocks, and in addition to the arrangement of strata, reveals clues about the Earth’s
past environments.
Sedimentary rocks are not only layered but may also be jointed, folded, and faulted. Both igneous and
sedimentary rocks are subject to metamorphism, which results from extreme heat and pressure.
Metamorphic rocks tend to be more resistant to erosion than their prior sedimentary forms; nevertheless,
metamorphic rocks are usually weak along their foliation planes. The formation, metamorphosis, and
destruction of rocks represent a continuous process known as the rock cycle.
Teaching Objectives
•
To discuss the circumstances under which sedimentary and metamorphic rocks form
•
To identify common sedimentary and metamorphic rock types
•
To discuss some observable structures within sedimentary and metamorphic rock masses
Lecture Outline
•
•
•
Sedimentary Rocks
o
Clastic and nonclastic sedimentary rocks
o
Sedimentary rocks in the landscape
o
Features of sedimentary strata
Metamorphic Rocks
o
Metamorphic rock types
o
Metamorphic rocks in the landscape
The Rock Cycle
Media Resources
Basic information about sedimentary rocks: http://www.geocities.com/RainForest/Canopy/1080/sedimentary.htm
Oil Museum of Canada: http://www.lambtononline.ca/oil_museum
Organization of Sedimentary Rock Site: http://csmres.jmu.edu/geollab/Fichter/SedRx/
Review Questions
1. How is a clastic rock different from a nonclastic rock?
2. What is compaction? What is cementation?
3. How are oil pools created?
4. What is cross-bedding?
5. Explain the difference between metamorphic rocks and sedimentary rocks
6. What is contact metamorphism?
7. Which metamorphic rock is hard to trace back to its pre-metamorphic form? Which pre-metamorphic
rock does it appear to be related to?
8. What were the Earth’s first rocks?
9. Why is it so difficult to piece together Earth’s geological record? What are the implications from
this?
10. Explain the rock cycle
Possible Assignments
•
Provide rock samples for the students to study. Use samples with different hardness,
cleavage/fracture, colour/streak, and luster. Have the students study and compare each
sample.
PowerPoint Lecture Guide
First Photo
Orphan Lake Trail, Lake Superior Provincial Park. Metamorphic processes led to the
formation of banded gneiss on the Canadian Shield.
Figure 31.1
From the Fieldnotes: “You can almost feel the power of the process that transported and
deposited this accumulation of poorly sorted sediment in its present location. Boulders lie
closer to the surface than smaller pebbles; many fragments are angular, suggesting
short-distance transportation and no time for rounding or sorting. It must have happened
very suddenly, a burst of force, perhaps during a major flood in this desert environment
(we are in a valley near the Gila River in eastern Arizona). This mass of material would
become a conglomerate if compaction and cementation followed. More likely, future
rainstorms and floods will carry most of it further downslope.”
Figure 31.2
Compaction and cementation in sedimentary rocks. In compaction (A), the grains are
packed tightly together by weight from above. In cementation (b), the spaces between the
grains are filled through the deposition of a cement, such as silica or calcium carbonate.
Figure 31.4
An oil pool (a body of rock in which oil occupies all the pore spaces) trapped in an
upward-arching layer of reservoir rock. These curving rock structures are known as folds,
and constitute the most important of all oil traps.
Figure 31.6
From the Fieldnotes: “Mediterranean shores provide instructive vistas, and even a local
ferry ride can constitute a lesson in physical geography. This exposed cliff on the Italian
island of Ischia reveals an eventful sedimentary and tectonic history. Unconformities
mark the lower strata (below the church on the cliffs flank). Note the contrasting angle of
dip of the light-coloured sandstone strata (upper right). Clearly, these layers were
deposited during times of much interrupted sedimentary deposition and repeated tectonic
activity.”
Figure 31.9
Two examples of contact metamorphism. The effects of two kinds of magmatic intrusions
on the existing sedimentary rock strata: metamorphism radiates deeply into these layers
from both the batholith and the dike (A). The effects of extrusion, in this case repeated
lava flows, on underlying sedimentary layers (B).
Figure 31.12
The rock cycle. The flow of materials within, above, and below the Earth’s crust
continually forms and destroys igneous, sedimentary, and metamorphic rocks.
References
Paradise, T.R. 1998. “Limestone weathering and rate variability, Great Temple of Amman, Jordan”,
Physical Geography 19(2): 133-146.
UNIT 32
LITHOSPHERIC PLATES
Unit Overview
This unit discusses the movement and interactions of lithospheric plates. The main sections are as
follows:
•
Continental drift
•
Continents, plate tectonics, and seafloors
•
Distribution of plates
•
Movement of plates
The continents once formed a “super-continent” called Pangaea. The continents separated by means of
continental drift, whereby the continents—drifting as a result of plate tectonics—function as rafts on the
ocean. Midoceanic ridges are corridors of seafloor spreading, where new crust is created and
subsequently moved away from these linear zones. The midoceanic ridges mark many of the boundaries
between the lithospheric plates. In addition to these zones of plate formation are zones of destruction,
where plate collision occurs.
The largest plates are as follows: Pacific, Eurasian, African, South American, Australian, Indian, and
Antarctic. Earthquakes and volcanoes are typically located at plate boundaries. The plates move relative
to one another and that movement is directly responsible for many of the Earth’s major landscapes and
landforms. The plates diverge, converge/collide, and displace laterally. Divergence results from crustal
spreading, which is not unique to midoceanic ridges. If plates form and spread outward in certain areas of
the crust, then they must converge and collide in other zones.
The three types of convergent plate boundaries are oceanic continental, oceanic-oceanic, and
continental-continental. The oceanic-continental convergence zones are characterized by subduction
zones, which are areas where an oceanic plate subducts beneath a continental plate. These subduction
zones are places of intense tectonic activity because of the melting of crust in the asthenosphere.
Subduction zones can also occur at oceanic-oceanic plate boundaries.
Continental-continental convergence involves negligible subduction; it instead produces massive
deformation and considerable buildup of crustal rock mass. The final type of plate contact involves lateral
motions. This lateral plate contact is characterized by transform faults, where plates slide past each other.
Like other plate boundaries, such plate movement is associated with earthquakes and crustal
deformation.
Teaching Objectives
•
To introduce the concepts of continental drift and plate tectonics
•
To identify the major plates of the lithosphere
•
To discuss the important boundary zones between the lithospheric plates in which rifting,
subduction, and transform faulting occur
Lecture Outline
•
•
Continental Drift
o
Pangaea
o
Laurasia
o
Gondwana
Continents, Plate Tectonics, and Seafloors
o
Seafloor spreading
o
Lithosphereic plates
o
Plate tectonics
•
•
Distribution of Plates
o
Pacific plate
o
North American plate
o
Eurasian plate
o
African plate
o
South American plate
o
Australian plate
o
Antarctic plate
o
Location of plate margins
o
Pacific ring of fire
Movement of Plates
o
o
Plate spreading

Rift valley

Crustal spreading
Plate collision

Subduction

Oceanic—Continental plate collision

Oceanic—Oceanic plate collision

Continental—Continental plate collision

Lateral plate contact
Media Resources
USGS information about the San Andreas Fault: http://pubs.usgs.gov/gip/earthq3/contents.html
Structure of the Earth: http://scign.jpl.nasa.gov/learn/plate1.htm
Plate Tectonic Animations: http://www.scotese.com/newpage13.htm
Plate Tectonics of Western Canada with links to the rest of the Canadian Geological Survey:
http://www.pgc.nrcan.gc.ca/seismo/eqinfo/plates.htm
Review Questions
1. Explain continental drift, including Pangaea and its sections
2. What is seafloor spreading?
3. What is a rift valley?
4. How many lithospheric plates have been mapped in total? What are the eight largest lithospheric
plates?
5. Which plates formally appeared to be one, but are now considered to be two different plates?
6. What tectonic phenomenon was a used as a clue to distinguish the locations of margins of
tectonic plates? Why was this an important clue?
7. What is the Pacific Ring of Fire?
8. Plate Margins take on three kinds of character. What are they?
9. What are the three types of plate collision?
10. What is lateral plate contact?
Possible Assignments
•
Investigate further the possibility of a large earthquake near Vancouver. What are your
feelings on the possibility of a large event occurring? Do you feel that the government and
public are doing enough to protect residents of the area?
•
What type of collision is occurring near Vancouver? What is some of the evidence in the area
that there is a fault nearby? (Look at Figure 32.12 in your textbook)
PowerPoint Lecture Guide
First Photo
Where plates diverge: new land arises from submarine eruptions related to the MidAtlantic Ridge south of Iceland.
Figure 32.1
The breakup of the super-continent Pangaea began more than 100 million years ago.
Note the radial movement of its remnants away from Africa and how areas of ancient
deposition help us to understand where today’s landmasses were once joined together.
Figure 32.3
Lithospheric plates of the Earth. Each drifts continuously in the direction shown by the
arrows. As the legend indicates, plate-boundary movement falls into one of three
categories: divergence (spreading), convergence, or lateral motion.
Figure 32.4
The global distribution of recent earthquakes and active volcanoes.
Figure 32.6
The development of a rift valley involves tensional movement related to motion in the
mantle, faulting (f), the collapse of elongated strips of crust (A), and crustal thinning.
Sometimes lava erupts along the tensional fault planes (V). Lakes fill large portions of rift
valleys in East Africa.
Figure 32.7
When continental plate A, moving eastward, meets oceanic plate B, moving westward,
the process of subduction carries the heavier oceanic plate downward beneath the
thicker but lighter continental plate. In this process, high relief develops along the
coastline, the continental crust is heavily deformed, and magma can penetrate through
vents and fissures (f) to erupt as lava at the surface.
Figure 32.8
A convergent plate boundary involving two oceanic plates. Where one oceanic plate is
subducted beneath the other, a deep oceanic trench forms. Above the trench, on the
margin of the upward-riding plate, an island arc is created by volcanic activity.
Figure 32.9
Two continental landmasses collide at a convergent plate boundary. There is much
deformation of the crust, and high relief develops (South Asia’s Himalayas mark such a
convergent continental plate boundary). But while there is considerable thickening of the
crust, less actual subduction occurs than when contrasting continental and oceanic plates
converge.
Figure 32.11
California’s San Andreas Fault in its regional context. This fault separates the Pacific
Plate from the North American Plate, which here are sliding past each other.
References
There are no additional references for this unit.
UNIT 33
PLATE MOVEMENT: CAUSES AND EFFECTS
Unit Overview
This unit examines the theoretical processes initially responsible for plate tectonics as well as the ultimate
effects of plate tectonics. The main sections are as follows:
•
Mechanism of crustal spreading
•
Evolution of continents
•
Isostasy
Plate movement is a confirmed lithospheric process; however, the mechanism driving plate movement is
not completely understood. Plate movement is initiated by the formation of new crust from magma at
midoceanic ridges, and this new crustal material diverges slowly towards the continental margins that
border the ocean’s basins. Several theories suggest that the large-scale mechanism responsible for the
movement of lithospheric material involves convective cells that extend deep into the mantle.
Continents are assumed to have formed through the solidification of segments of the primitive crustal
sphere. Continents can also grow in areal extent by accreting smaller bodies of crustal known as
terranes. A phenomenon that controls the vertical extent of continental landmasses is isostasy—a
condition of equilibrium between floating landmasses and the asthenosphere beneath them. Tectonic and
erosional forces cause constant isostatic adjustments, which, in turn, explain why erosional forces have
not completely flattened all mountain ranges. In addition, the collision of drifting plates greatly affects
isostasy, principally through the process of mountain building. The appearance and removal of massive
ice sheets can also cause isostatic changes in the crust.
Teaching Objectives
•
To briefly outline the mechanisms and processes that move lithospheric plates
•
To discuss the evolution of the Earth’s continental landmasses
•
To discuss the concept of isostasy and relate it to the topography of the continents
Lecture Outline
•
Mechanism of Crustal Spreading
o
•
•
Models proposed by Holmes and Hess
Evolution of Continents
o
Crustal formation
o
The super-continent cycle of Wilson cycle
o
Terranes and exotic terranes
Isostasy
o
Everest “mountain roots”
o
Airy hypothesis
o
Isostasy and erosion
o
Isostasy and plate mobility
o
Isostasy and regional landscapes
o

Plains and uplands

Ice sheets and isostatic rebound
Dams and crustal equilibrium
•
Everest “mountain roots”
•
Airy hypothsis
•
Isostasy and erosion
•
Isostasy and plate mobility
•
Isostasy and regional landscapes
o
o
Plains and Uplands
o
Ice Sheets and Isostatic Rebound
Dams and Crustal Equilibrium
Media Resources
USGS This Dynamic Earth: the Story of Plate Tectonics: http://pubs.usgs.gov/publications/text/dynamic.html
Description of the Evolution of the Continents: http://www.geocities.com/earthhistory/plate3.htm
Pacific Geoscience Centre: http://www.pgc.nrcan.gc.ca/tectonic/techome.htm
Website that outlines seismology and seismic archives related to Western Canada:
http://www.pgc.nrcan.gc.ca/seismo/table.htm
Isostasy: http://www.homepage.montana.edu/~geol445/hyperglac/isostasy1/
Review Questions
1. Explain the two main theories behind crustal spreading. Explain Figure 33.3.
2. What is the Supercontinent and what were the steps involved in its breakup?
3. What is accretion? What are terranes? What are exotic terranes?
4. Explain Figure 33.4
5. What is isostasy?
6. What are the two reasons that are through to cause vertical changes in the Earth’s crust?
7. What are the “roots” of mountains? What is the Airy hypothesis?
8. What would happen if a high mountain range were subjected to erosion?
9. What is the Benioff Zone?
10. Isostatic uplift occurs differently in plains and uplands. How so?
Possible Assignments
•
Go to the following website and observe some the animation:
http://www.geo.wvu.edu/~donovan/geol101/animations/56.swf. Describe what the animation
is showing you. Why is isostasy important?
PowerPoint Lecture Guide
First Photo
On the margin of the Caribbean Plate: lava boils near the base of Gros Piton near
Sourfriere on the eastern Caribbean island of St. Lucia.
Figure 33.2
Current lithospheric plate velocities in centimetres per year.
Figure 33.3
Convection cells in the mantle may look like this in cross-section. Hot magma rises at A,
spreads toward B, and in the process drags the existing oceanic crust with it. At the
spreading midoceanic ridge, new oceanic crust is being created from some of this
upwelling magma. As the material below the crust spreads toward B, it cools slowly.
When it reaches a convergent boundary with a continental landmass, the oceanic crust is
subducted. The material in the convection cell now moves toward C, reheating at this
depth. By the time it has passed C, it has enough energy to rise again into the spreading
ridge. Speed of movement may be only about 2.5 cm (1 in) per year.
Figure 33.5
From the Fieldnotes: “Traversing Glacier Bay in southeast Alaska, we were given a
seminar by a National Park Service guide who enjoyed asking challenging questions.
Knowing some physical geography helped, but here she had me stumped. ‘Look at that
outcrop,’ she said. ‘What can you tell me about it?’ I said that the rocks looked darker
than the regional gray-granite masses rising steeply from the bay, but in the absence of
any knowledge of volcanic activity here, I could not do any better. ‘You’re looking at lava,’
she explained; ‘this is a fragment of one of those suspect terranes, an old basaltic island
arc welded onto the local regional geology. It’s called Wrangellia, and pieces of it can be
identified from mainland Alaska all the way down the coast to British Columbia and the
U.S. Northwest. It’s out of place and we don’t know how it got here, but it sure stands out
in this landscape.’ That is the kind of field experience you don’t forget.”
Figure 33.7
The Airy hypothesis: mountain ranges have roots of sialic rock that penetrate the denser
simatic rock below.
Figure 33.8
Isostasy. The distribution and behavior of sial and sima is analogous to blocks of copper
floating in mercury. Note that, no matter how thick the block, the same percentage (35
per cent/65 per cent) floats above and below the surface. Each block is therefore in
balance.
References
Harrison, M.T., et al. 1992. “Raising Tibet”, Science 255 (March 27): 1663-1670.
UNIT 34
VOLCANISM AND ITS LANDFORMS
Unit Overview
This unit examines volcanic activity across the globe. The main sections are as follows:
•
Distribution of volcanic activity
•
Volcanic mountains
•
Calderas
•
Landscapes of volcanism
Volcanism is the eruption of molten rock at the Earth’s surface, which is often accompanied by rock
fragments and explosive gases. Besides being associated with seafloor spreading at midoceanic ridges,
volcanism also occurs at subduction zones, specifically convergent plate boundaries. Volcanism is also
associated with intraplate hot spots—subcrustal, stationary plumes of extraordinarily high heat over which
lithospheric plates move.
Volcanism produces lava, and the mineral content of the lava determines its viscosity and gaseous
content. For example, basaltic lava, which occurs in oceanic plates, has a much lower viscosity and
contains fewer gases than other types of lava because of its low silica content and high iron and
magnesium content. Consequently, basaltic lava flows more easily and is less explosive than other types
of lava. Landforms forming from lava are a function not only of the composition of the lava but also of the
vent, the thickness of the lava flow, and the nature of the surface over which the lava spreads.
The four types of volcanic landforms are composite volcanoes, lava domes, cinder cones, and shield
volcanoes. Composite volcanoes are steep-walled “mountains” that form over subduction zones; they are
characterized by pyroclastics and viscous lava. Lava domes are relatively small mounds formed by the
oozing of lava with minimal pyroclastic activity. Cinder cones, which are also relatively small, consist
almost entirely of pyroclastics. Shield volcanoes are formed from basaltic lavas associated with a hot spot
and can exhibit a considerable horizontal extent.
The magma reservoir inside a volcano can be reduced, at which point it will cease to support the volcano.
The volcano collapses and a caldera forms. The magma reservoir can also be penetrated by water,
thereby producing explosive events known as phreatic eruptions.
Teaching Objectives
•
To relate volcanic activity to plate boundary types
•
To discuss typical landforms produced by volcanic eruptions
•
To cite some dramatic examples of human interactions with volcanic environments
Lecture Outline
•
•
Distribution of Volcanic Activity
o
Active, dormant, and extinct volcanoes
o
Lava and landforms
Volcanic Mountains
o
•
Composite volcanoes

Lahars

Nuees ardentes

Predicting risk
o
Lava Domes
o
Cinder Cones
o
Shield Volcanoes
o
Hot Spots
o
Hot Spots and Plate Dynamics
Calderas
o
Phreatic eruptions
•

Krakatau

Tambora

Santorini
Landscapes of Volcanism
o
Italy
o
Japan
o
North America
Media Resources
The Geological Survey of Canada: http://www.nrcan.gc.ca/gsc/pacific/vancouver/volcanoes/index_e.html
This USGS page provides basic and historical information about volcanoes, and has links to USGS
worldwide volcano monitoring programs: http://volcanoes.usgs.gov
The Global Volcanism Program: http://www.volcano.si.edu/world/
Exploring the Environment – Volcanoes: http://www.cotf.edu/ete/modules/volcanoes/vtypesvolcan1.html
Savage Earth – Animation: http://www.pbs.org/wnet/savageearth/animations/volcanoes/
Review Questions
1. What are active, dormant and extinct volcanoes?
2. What is the difference between magma and lava?
3. What are pyroclastics?
4. Why are composite volcanoes so dangerous? What type of lava do they contain?
5. What are lahars and why are they so dangerous?
6. What characteristic gave shield volcanoes their name?
7. Explain the term pahoehoe.
8. How many volcanic belts does Canada have?
9. What is the theory behind hot spots? How do they relate to plate dynamics?
10. What creates a caldera and where are they likely to be found?
Possible Assignments
•
How would living near an active volcano affect one’s lifestyle?
PowerPoint Lecture Guide
First Photo
Near Armadillo Peak, Mount Edziza, British Columbia. Over the ages, ice and fire formed
this glacier-tipped volcanic mountain.
Figure 34.2
During a fissure eruption, lava flows onto the surface and spreads out in a sheet rather
than forming a dome. When the fissure opens again, a later, younger flow (Y) will cover
all or part of the older lava sheet (0).
Figure 34.3
A. The Chilcotin Plateau basalt flows in the interior of British Columbia. B. The chasm,
British Columbia. Erosion has revealed varying tones of red, brown, yellow and purple,
formed by successive lava flows.
Figure 34.4
Simplified cross-section of a composite volcano, showing a sequence of lavas
interspersed with compacted pyroclastics.
Figure 34.7
From the Fieldnotes: “East Africa’s volcanic landscape displays landforms ranging from
great peaks such as Mounts Kilimanjaro and Kenya to small cinder cones and local
fissure eruptions. Driving across this area you are reminded that volcanic activity
continues; some of the cinder cones have not yet developed much vegetation. Elsewhere
plants are just beginning to establish themselves on the lava. In places the landscape
poses challenging questions. Many cinder cones, for example, have small crater-like
depressions near their crests, but those’ craters’ tend to lie to one side, as in this photo
taken in Kenya. As it happens a majority of them lie in the same compass direction from
the top of the hill. What might be the cause of this pattern?”
Figure 34.10
Simplified cross-section of a shield volcano. Vertical scale is greatly exaggerated. The
base of this volcano extends over 320 km (200 mi); its height above the ocean floor is
around 13 km (8 mi).
Figure 34.11
From the Fieldnotes: “Spending a semester teaching at the University of Hawai’i gave me
the opportunity to spend much time on the Big Island, where the great volcanoes are
active today. Here on Hawai’i, the product of very recent (and current) shield volcanism,
snow dusts the mountaintops even as palm trees grace the tropical beaches. To
experience an area where the night sky reflects the glow of molten magma and the day
reveals clouds of superheated gases emanating from caldera walls is memorable. Shown
here is a mass of recently erupted pahoehoe lava, its smooth ‘skin’ wrinkled into ropy
patterns by continued movement of molten rock inside.”
Figure 34.13
When the magma chamber that has long supplied an active volcano is somehow
deprived of its conduit to the magma source; it empties out, leaving a hollow chamber
beneath the cone. Eventually, the structure of the volcano yields and the cone collapses,
creating a caldera.
Figure 34.14
A and B From the Fieldnotes: “To realize what happened here, how a gigantic volcanic
explosion changed the course of human history, is to be reminded how vulnerable
humanity remains to nature’s power. Thera (Santorini) bears witness to a day, more than
3600 years ago, when Minoan civilization thrived and Thera was the Hong Kong of the
eastern Mediterranean. In a cataclysmic event, the mountain that was Thera was
pulverized, huge blocks of rock fell back into the Mediterranean, poisonous ash rained on
countrysides hundreds of kilometres away, and dust encircled the Earth for years. Towns,
villages, farms, and ports on prosperous Thera disappeared; Minoan civilization on
nearby Crete may have been dealt a fatal blow. What was left was an enormous caldera,
60 km (37 mi) in circumference, open to the sea, on whose inner wall homes and
businesses now perch precariously (A). But Santorini’s activity has not ended, and
earthquakes continue to destroy lives and property. A new central cone is slowly rising in
the center of the caldera, where fresh lava signals the rise of a new mountain (B). In the
background, atop the caldera wall, is the much-damaged town of Oja.”
Figure 34.15
The Cascade volcanoes of the U.S. Pacific Northwest and adjoining Canada.
References
Carey, H., et al. 1992. “Fire and Water at Krakatau”, Earth 1(March): 26-35.
Parks, N. 1994. “Exploring Loihi: The Next Hawaiian Island”, Earth, 3(September): 56-63.
Pendick, D. 1995. “Return to Mt. St Helens”, Earth, 4(April): 24-33.
UNIT 35
EARTHQUAKES AND LANDSCAPES
Unit Overview
This unit explores earthquakes and resultant processes and landscapes. The main sections are as
follows:
•
Earthquake terminology
•
Earthquake distribution
•
Earthquakes and landscapes
•
Tsunamis
An earthquake is the release of energy that has been slowly building up during the stress of the
increasing deformation of rocks. Earthquakes either produce faults or originate at them. Faults are
fractures in crustal rock involving the displacement of rock on one side of the fracture with respect to rock
on the other side. Earthquakes originate at the “focus”—the point at the surface directly above the focus is
the epicentre of the earthquake.
Earthquakes generate seismic waves, and these waves determine an earthquake’s magnitude and
intensity. Earthquakes are concentrated in the CircumPacific and Trans-Eurasian belts of subduction
zones as well as along midoceanic ridges. Intraplate earthquakes also occur.
Similar to volcanic eruptions, earthquakes can alter physical and cultural landscapes. Earthquakes can
also produce giant sea waves known as tsunamis when the epicentre is located on the ocean floor or
near a coastline. Tsunamis can, in turn, modify local physical and cultural landscapes.
Teaching Objectives
•
To describe and quantify the magnitude and intensity of earthquakes
•
To relate the spatial pattern of earthquakes to plate tectonics
•
To discuss landscapes and landforms that bear the signature of earthquake activity
Lecture Outline
•
•
•
•
Earthquake Terminology
o
Focus
o
Epicentre
o
Magnitude
o
Intensity
Earthquake Distribution
o
Circum-Pacific belt
o
Trans-Eurasian belt
o
Midoceanic ridges
o
Intraplate earthquakes
Earthquakes and Landscapes
o
Fault scarp
o
Fault plane
Tsunamis
o
Causes
Media Resources
The Geological Survey of Canada: http://gsc.nrcan.gc.ca/index.html
The USGS Earthquake Hazards Site: http://quake.wr.usgs.gov
Earthquake Risk in Canada: http://www.swissre.com/INTERNET/pwswpspr.nsf/alldocbyidkeylu/SBAT534B24?OpenDocument
Geological Survey of Canada’s Pacific Geosciences Centre:
http://www.pgc.nrcan.gc.ca/sidney.index_e.html
NOAA Data from its Tsunami Research Program: http://www.pmel.noaa.gov/tsunami
Maps of Earthquakes in Canada: http://www.pgc.nrcan.gc.ca/seismo/recent/eqmaps.html
Earthquakes Canada: http://www.seismo.nrcan.gc.ca/index_e.php
Review Questions
1. What is an earthquake?
2. What is the difference between the epicentre and the focus of and earthquake?
3. What is the difference between magnitude and intensity?
4. What is the Richter Scale?
5. What is the Modified Mercalli Scale? What is the Moment Magnitude Scale?
6. How many known earthquake belts are there? Which is the most active? Which poses the most
threat to humans?
7. What is an intraplate earthquake?
8. What are the fault scarp and fault plane?
9. What parts of North America are considered free from earthquake risk?
10. What is a tsunami?
Possible Assignments
•
On 26 December 2004 a catastrophic tsunami hit many countries in Southeast Asia. What
were the outcomes of the event? Did anyone know the tsunami was coming? Were people
warned? How are the countries coping?
PowerPoint Lecture Guide
First Photo
What sounded and felt like a violent thunderclap produced a tear in our parking lot, a
reminder of the instability of the still-building crust of Hawai’i’s Big Island.
Figure 35.1
When stress (in this case compression) affects horizontal rock layers (A), the strata begin
to bend, and they continue to do so as long as their rupture strength is not exceeded (B).
When this level is exceeded, a fault plane (f-f1) develops (C). Often, more than one such
fault plane will be formed. Sudden movement along this fault plane, accompanied by one
or more earthquakes, relieves the now-exceeded rupture strength, and the rock strata
resume their original (horizontal) position (D).
Figure 35.2
In an area honeycombed by faults (f), movement on a particular fault plane (perhaps at
intersecting faults) becomes the focus for energy release. The epicenter is the point at
the earth’s surface vertically above the point of focus. The energy released at the
earthquake’s focus radiates outward to other parts of the earth in the form of seismic
waves, represented by the rings spreading from the focus and the epicenter.
Figure 35.6
Global distribution of recent earthquakes. The deep earthquakes, shown by black dots,
originated more than 100 km (63 mi) below the surface.
Figure 35.7
A fault scarp resulting from the vertical movement of one block with respect to another.
The blocks are in contact along the fault plane, whose exposed face is the fault scarp. If
the upper block were eroded down to the level of the lower block, the only surface
evidence of the fault plane would be the fault trace.
References
Davidson, K. 1994. “Learning from Los Angeles”, Earth, 3(September): 40-48.
Johnston, A. 1992. “New Madrid: The Rift, the River and the Earthquake”, Earth, 1(January): 34-43.
Johnston, A.C., and L.R. Kantner. 1990. “Earthquakes in the Stable Continental Crust”, Scientific
American, 262(March): 68-75.
Monastersky, R. 1990. “Rattling the Northwest”, Science News, 137(February 17): 104-106.
Palm, R.L. 1981. “Public response to earthquake hazard information”, Annals of the Association of
American Geographers, 71(3): 389-399.
UNIT 36
SURFACE EXPRESSIONS OF SUBSURFACE STRUCTURES
Unit Overview
This unit examines geologic features resulting from interactions between lithospheric plates. The main
sections are as follows:
•
Terminology of structure
•
Fault structures
•
Fold structures
•
Regional deformation
There is a strong relationship between geologic structure and surface landscape. Landscape features,
often in the form of outcrops (a locality where exposed rock occurs), include faults and folds.
Plate tectonics are primarily responsible for faulting and folding. A fault is a fracture in crustal rock
involving the displacement of rock on one side of a fracture with respect to rock on the other side. Faulting
results when brittle rocks come under stress and break because they cannot bend or fold. Faults can be
compressional, tensional, or transverse.
The vertical movement of blocks results from both converging and diverging plates, and the associated
faults are compressional faults and tensional faults, respectively. Transverse faults are associated with
horizontal motion along the fault plane. Common forms of compressional, tensional, and transverse faults
are reverse, normal, and transcurrent faults, respectively.
Folding can occur in place of, or in addition to, faulting. All rocks have the ability to fold, and the resulting
folds are primarily compressional features. Common topographic structures indicative of folding are
anticlines and synclines. An anticline is an arch-like fold with the limbs dipping away from the axis, while a
syncline is trough-like with limbs dipping toward the axis. Younger rocks constitute the cores of synclines
in a sedimentary context. Anticlines and synclines are often plunging, thus their axes dip. Over large
areas of stable lithosphere, faulting or folding is minimal; instead, slight deformation may exist.
Teaching Objectives
•
To introduce basic terminology used in describing rock structure
•
To distinguish between types of fault movements and the landforms they produce
•
To discuss the folding of rocks and relate it to the landforms produced
Lecture Outline
•
•
•
•
Terminology of Structure
o
Strike
o
Dip
o
Outcrop
Fault Structures
o
Fault
o
Compressional faults
o
Tensional faults
o
Transverse faults
o
Field evidence of faulting
Fold Structures
o
Anticlines and synclines
o
Plunging folds and associated landscapes
Regional Deformation
o
Diastrophism
o
Crustal warping
Media Resources
Information about plate tectonics: http://www.platetectonics.com/index.asp
Geologic Structures: http://courses.smsu.edu/ejm893f/creative/glg110/GeoStruct.html
Geologic Structural Animations: http://www.structural-geology-portal.com/animations.html
Review Questions
1. Define strike and dip.
2. What is a fault? What are the three types of faults? Describe each.
3. In a reverse fault, what happens to the overhanging scarp?
4. What is a horst? What are grabens?
5. What are the upthrown and downthrown blocks?
6. How far does the African rift-valley system stretch?
7. What anticlines and synclines? How are they similar? How are they different?
8. Is there always symmetry to anticlines and synclines?
9. What are primary and secondary landforms?
10. What is diastrophism?
Possible Assignments
•
In 10 million years, Africa could look quite different than it does now if the East African Plate
completes its separation from the rest of the continent. Are there any other places in the
world where a situation like this is occurring? What are the possible outcomes? What could
the world look like?
PowerPoint Lecture Guide
First Photo
Agents of erosion have exposed a volcanic plus (Black Tusk) in the garibaldi Provincial
Park, Southwestern British Columbia.
Figure 36.1
Strike, direction of dip, and angle of dip.
Figure 36.2
In a reverse fault, the overhanging scarp of the upthrown block (A) soon collapses, and a
new slope, which lies at an angle to the original, is produced by erosional forces (B).
Figure 36.3
A plateau formed as an upthrown block between two reverse faults that run parallel to
each other where they intersect the surface.
Figure 36.4
Side view of a thrust fault resulting from compression. The low angle of the fault plane
produces substantial overriding by the upthrown block.
Figure 36.5
Unlike compressional stresses, tensional stresses pull the crust apart. Normal faults
result, and the fault scarp often reflects the dip angle of the fault plane.
Figure 36.6
Formation of a rift valley as tensional forces generate parallel normal faults between
which crustal blocks slide downward.
Figure 36.7
The African rift-valley system extends from beyond Africa in the north (the Jordan-Aqaba
segment) to Swaziland in the south.
Figure 36.9
The possible configuration of Africa, ca. 10 million years from now, if the East African
Plate (inset map) completes its separation from the rest of the continent.
Figure 36.10
A horizontal or transcurrent fault, also known as a strike-slip fault.
Figure 36.11
From the Fieldnotes: “The Mescal Mountains in south-central Arizona display some
complex structures. The sedimentary strata shown here were laid down horizontally, but
were later folded into the anticline of which both limbs are visible in the lower half of the
photo and one in the upper part.”
Figure 36.12
Anticlines are arching upfolds, while synclines are trough-like downfolds. Note the relative
age of rock layers within each type of fold.
Figure 36.13
An eroded anticline-syncline landscape of surface outcrops with parallel strikes (A). The
age sequence of these rock formations can be interpreted by referring to the geologic
map (B) below the block diagram.
Figure 36.14
An anticline-syncline structure, plunging in opposite directions.
Figure 36.16
Extreme compression can produce folds that double back upon themselves with axial
planes that approach the horizontal. The anticline in (A) is termed recumbent; the
anticline in (B) is classified as overturned.
References
There are no additional references for this unit.
UNIT 37
THE FORMATION OF LANDSCAPES AND LANDFORMS
Unit Overview
This unit, which introduces Part V: Sculpting the Surface, discusses primarily the process of erosion and
its importance in the degradations and aggradations of landmasses. The main sections are as follows:
•
Landscapes and landforms
•
Gradation
•
Erosion and tectonics
•
Regional landscapes
A landform is defined as a single unit that forms part of the general topography of the Earth’s surface.
Therefore, a landscape contains an assemblage of landforms, and the landforms are the product of
intervening processes.
Gravity is the major force driving gradation—the leveling of a topographic surface. Gradation is comprised
of both degradation and aggradation. These two processes operate together, with degradation wearing
down a portion of a landmass and aggradation building up another portion. Degradational processes
involve weathering, mass movements, and erosion. Weathering is the in situ disintegration of rocks, and it
can involve mechanical, chemical, or biological processes. Mass movement is the spontaneous
downslope movement of materials under the force of gravity (e.g., landslides). Erosion is the carrying of
weathered and mass-moved material over long distances. Additional disintegration of materials occurs as
materials are being eroded. Running water is the predominant agent of erosion across the globe. Other
erosional agents include glaciers, winds, and coastal waves.
Degradational agents can also be aggradational agents, because what is removed from one location is
deposited in another location. Erosion is not the only process acting on landmasses. Landmasses can be
rejuvenated tectonically as they are worn down by erosion. Related to this condition is the principle of
isostasy, where the removal of a large volume of rock (or other overburden) from an area of the crust
leads to an upward rebound of that part of the landmass. Upward rebounding of the lithosphere
compensates for downward erosion. Consequently, erosion is an indefinite and inescapable process.
Teaching Objectives
•
To introduce three primary degradational processes: weathering, mass movements, and
erosion
•
To focus attention on the aggradational processes that produce secondary landforms
•
To recognize the roles of degradation and aggradation in the formation and evolution of
landscapes
Lecture Outline
•
•
Landscapes and Landforms
o
Landscape
o
Landform
Gradation
o
Degradation
o
Degradational processes and landscapes

Running water

Glaciers

Wind

Coastal waves

Chemical dissolution
o
•
Erosion and Tectonics
o
•
Aggradational processes and landforms
How would erosion impact the Earth if plate tectonics didn’t exist?
Regional Landscapes
o
Regional physiography
Media Resources
A graphical representation of the geological time scale from the USGS:
http://pubs.usgs.gov/gip/geotime/time.html
Cyrosphere System in Canada – Glaciers & Ice Caps: http://www.msc.ec.gc.ca/crysys/
Wind Erosion: http://www.uwgb.edu/dutchs/EarthSC202Notes/WINDeros.HTM
Review Questions
1. What is the difference between a landform and a landscape?
2. What is the key force regarding gradation?
3. What is degradation? What are the categories degradational processes can be divided into?
What is aggradation?
4. What is the most significant agent of erosion?
5. What are some of the landforms that were shaped by glaciers?
6. Why are coastal landscapes of such special interest in physical geography?
7. What is chemical dissolution?
8. How would erosion impact the Earth if plate tectonics did not exist?
9. In which geological period did Pangaea break-up?
10. Why will erosion continue on indefinitely?
Possible Assignments
•
Using the ratio of one year of human life represents 230 million years of the Earth’s life,
determine the physical changes that could occur on the Earth in an average human lifetime.
(Hint: average human lifetime multiplied by 230 million).
PowerPoint Lecture Guide
First Photo
The Pinnacles, columnar remnants of a limestone formation, on the west coast of
Australia.
Figure 37.1
From the Fieldnotes: “Driving westward from Christchurch, New Zealand, across the
Canterbury Plain and into the mountains via Arthur’s Pass, you encounter diverse
landscapes. On the way up, the evidence of recent glaciation is all around, but now
subaerial processes (that is, those proceeding under atmospheric conditions) prevail, and
weathering, mass movement, and stream erosion are modifying topography. Here, in the
Craigeburn area, a talus cone or scree slope has formed from rock originally loosened
under glacial conditions, augmented now by mechanical weathering and moved
downslope under the force of gravity. The talus has not moved far from its source; stream
erosion is not yet playing a major role here.”
Figure 37.6
From the Fieldnotes: “Oregon’s coastal Route 101 provides some magnificent scenery
and many superb field examples of coastal landforms. Drive it southward, so you are on
the ocean side! Ample rainfall in this Cfb environment sustains luxuriant vegetation;
below, the waves do their work even as tectonic forces modify the geology. Here two
natural bridges have formed following wave penetration of a fault-weakened section of
the coastline, the waters rushing in through one and out through the other.”
References
Phillips, J.D. 1997. “A short history of a flat place: three centuries of geomorphic change in the Croatan
National Forest”, Annals of the Association of American Geographers 87(2): 197-216.