Chapter 11
The Dynamic Planet
Geosystems 5e
An Introduction to Physical Geography
Robert W. Christopherson
Charlie Thomsen
Overview
Earth is a dynamic planet whose surface is actively shaped by physical
agents of change. Part Three is organized around two broad systems
of these agents—the internal (endogenic) and external (exogenic).
The endogenic system (Chapters 11 and 12) encompasses internal
processes that produce flows of heat and material from deep below the
crust, powered by radioactive decay. This is the solid realm of Earth.
“The Ocean Floor” chapter-opening illustration that begins Chapter 12
is used as a bridge between these two endogenic chapters. The
exogenic system (Chapters 13–17) includes external processes that set
air, water (streams and waves), and ice into motion, powered by solar
energy. This is the fluid realm of Earth's environment. These media
are sculpting agents that carve, shape, and reduce the landscape. The
content is organized along the flow of energy and material or in a
manner consistent with the flow of events.
Overview Cont’d
after reading the chapter you should be able to:”
Distinguish between the endogenic and exogenic systems,
determine the driving force for each, and explain the pace at
which these systems operate.
Diagram Earth’s interior in cross section and describe each
distinct layer.
Illustrate the geologic cycle and relate the rock cycle and
rock types to endogenic and exogenic processes.
Describe Pangaea and its breakup and relate several
physical proofs that crustal drifting is continuing today.
Portray the pattern of Earth's major plates and relate this
pattern to the occurrence of earthquakes, volcanic activity,
and hot spots.
Study Through Chapter Review
Questions: (p.353-354)
The questions posed in this lecture will help
you:
Distinguish between the endogenic and
exogenic systems, determine the driving
force for each, and explain the pace at
which these systems operate.
1. To what extent is Earth's crust actively building at
this time in its history?
The U.S. Geological Survey reports that, in an
average year, continental margins and seafloors
expand by 1.9 km3. But, at the same time, 1.1 km3
are consumed, resulting in a net addition of 0.8 km3
to Earth's crust. The results are irregular patterns of
surface fractures, the occurrence of earthquakes and
volcanic activity, and the formation of mountain
ranges.
2. How is the geologic time scale organized? What is the
basis for the time scale in relative and absolute terms? What
era, period, and epoch are we living in today?
The geologic time scale (Figure 11-1) reflects currently accepted
names and the relative and absolute time intervals that encompass
Earth's history (eons [~1 billion years], eras [usually at least 50
million years], periods [a division of geologic time longer than an
epoch and included in an era], and epochs [usually les than tens of
millions of years ago]). The sequence in this scale is based upon the
relative positions of rock strata above or below one another. An
important general principle is that of superposition, which states that
rock and sediment always are arranged with the youngest beds
“superposed” near the top of a rock formation and the oldest at the
base—if they have not been disturbed. The absolute ages on the scale,
determined by scientific methods such as dating by radioactive
isotopes, are also used to refine the time-scale sequence. The figure
presents important events in Earth's life history along with the
geologic time scale.
Fig 11.1: Geologic Time
Scale: Both the relative
and absolute dating
methods calibrate the
geologic time scale.
Relative dating determines
the sequence of events and
time intervals between
them. Technological
means, especially
radiometric dating,
determines absolute dates.
In the column on the left,
88% of geologic time
occurred during the
Precambrian Era.
3. Contrast uniformitarianism and catastrophism as
models for Earth's development.
Uniformitarianism assumes that the same physical
processes active in the environment today have been
operating throughout geologic time. The phrase
“the present is the key to the past” is an expression
coined to describe this principle. In contrast, the
philosophy of catastrophism attempts to fit the
vastness of Earth's age and the complexity of its
rocks into a shortened time span. Because there is
little physical evidence to support this idea,
catastrophism is more appropriately considered a
belief rather than a serious scientific hypothesis.
4. What is the structure of the Earth’s interior?
Layers defined by composition
Three principal compositional layers:
 Crust—The
comparatively thin outer skin that ranges
from 3 km (2 miles) at the oceanic ridges to 70 km (40
miles in some mountain belts)
 Mantle—A solid rocky (silica-rich) shell that extends to a
depth of about 2900 km (1800 miles)
 Core—An iron-rich sphere having a radius of 3486 km
(2161 miles)
Cont’d
Layers defined by physical properties
Lithosphere (sphere of rock)
 Consists
of the crust and uppermost mantle
 Relatively cool, rigid shell
 Averages about 100 km in thickness, but may be 250 km
or more thick beneath the older portions of the
continents
Asthenosphere (weak sphere)
 Beneath
the lithosphere, in the upper mantle to a depth
of about 600 km
 Small amount of melting in the upper portion
mechanically detaches the lithosphere from the layer
below allowing the lithosphere to move independently of
the asthenosphere
Cont’d
Mesosphere or lower mantle
 Rigid
layer between the depths of 660 km and 2900 km
 Rocks are very hot and capable of very gradual flow
Outer core
 Composed
mostly of an iron-nickel alloy
 Liquid layer
 2270 km (1410 miles) thick
 Convective flow within generates Earth’s magnetic field
Inner core
 Sphere
with a radius of 3486 km (2161 miles)
 Stronger than the outer core
 Behaves like a solid
Earth’s Layered Structure
5. What is a discontinuity?
A discontinuity is a place where a change in
physical properties occurs between two regions deep
in Earth's interior. A transition zone of several
hundred kilometers marks the top of the outer core
and the beginning of the mantle. The boundary
between the crust and the rest of the lithospheric
upper mantle is another discontinuity called the
Mohorovicic discontinuity, or Moho for short,
named for the Yugoslavian seismologist who
determined that seismic waves change at this depth,
owing to sharp contrasts of materials and densities.
6. What is the present thinking on how Earth generates its
magnetic field? Is this field constant, or does it change?
The fluid outer core generates at least 90% of Earth's magnetic
field and the magnetosphere that surrounds and protects Earth
from the solar wind (A flow of gas and energetic charged
particles, mostly protons and electrons [plasma] which stream
from the sun). An intriguing feature of Earth's magnetic field is
that it sometimes fades to zero and then returns to full strength
with north and south magnetic poles reversed! In the process,
the field does not blink on and off but instead oscillates slowly
to nothing and then slowly regains its strength. (New evidence
suggests the field fades slowly to zero, then when it returns it
tends to do so abruptly.) This magnetic reversal has taken place
nine times during the past 4 million years and hundreds of
times over Earth's history. The average period of a magnetic
reversal is 500,000 years, with occurrences as short as several
thousand years possible.
7. Define isostasy and isostatic rebound, and
explain the crustal equilibrium concept.
The principle of buoyancy (that something less
dense, like wood, floats in denser things like water)
and the principle of balance were further developed
in the 1800s into the important principle of isostasy
to explain certain movements of Earth's crust. The
entire crust is in a constant state of compensating
adjustment, or isostasy, slowly rising and sinking in
response to its own weight, and pushed and dragged
about by currents in the asthenosphere (see Figure
11-4).
Earth’s entire crust is
in a constant state of
compensating
adjustment, Example:
(a): Mountain mass
slowly sinks
(b): do to loss of mass
from mountain
(erosion), the crust
adjusts upward.
(c): Deposition of some
of the sediments from
the mountain is
deforming the
Lithosphere
downward.
8. Define each component: hydrologic cycle ,rock cycle, and
tectonic cycle.
The hydrologic cycle is the vast system that circulates water, water
vapor, ice, and energy throughout the Earth-atmosphere-ocean
environment. This cycle rearranges Earth materials through erosion,
transportation, and deposition, and it circulates water as the critical
medium that sustains life.
The rock cycle, through processes in the atmosphere, crust and
mantle, produces three basic rock types: igneous, sedimentary, and
metamorphic.
- Igneous rock is a rock that solidifies and crystalizes from a molten
state (lava).
- Sedimentary rock is formed through pressure –the cementation,
compaction and hardening of sediment.
- Metamorphic rock – Any rock (igneous of sedimentary) can be
transformed into metamorphic rock by going through profound
physical or chemical changes and increased temperature.
Cont’d
Tectonic cycle - The tectonic cycle brings
heat energy and new materials to the surface
and recycles old materials to mantle depths,
creating movement and deformation of the
crust.
9. What is a mineral? A mineral family? Name the most
common minerals on Earth. What is a rock?
A mineral is an element or combination of elements that forms an
inorganic natural compound. A mineral can be described with a
specific symbol or formula and possesses specific qualities. Silicon
(Si) readily combines with other elements to produce the silicate
mineral family, which includes quartz, feldspar, amphibole, and clay
minerals, among others. Another important mineral family is the
carbonate group, which features carbon in combination with oxygen
and other elements such as calcium, magnesium, and potassium. Of
the nearly 3000 minerals, only 20 are common, with just 10 of those
making up 90% of the minerals in the crust. A rock is an assemblage
of minerals bound together (such as granite, containing silica,
aluminum, potassium, calcium, and sodium) or sometimes a mass of a
single mineral, such as rock salt.
10. The igneous process in detail. What is the difference between
intrusive and extrusive types of igneous rocks?
Rocks that solidify and crystallize from a molten state are
called igneous rocks. Most rocks in the crust are igneous.
They form from magma, which is molten rock beneath the
surface (hence the name igneous, which means fire-formed
in Latin). Magma is fluid, highly gaseous, and under
tremendous pressure. It is either intruded into preexisting
crustal rocks, known as country rock, or extruded onto the
surface as lava. The cooling history of the rock–how fast it
cooled, and how steadily the temperature dropped–
determines its texture and degree of crystallization. These
range from coarse-grained (slower cooling, with more time
for larger crystals to form) to fine-grained or glassy (faster
cooling).
11. Describe sedimentary processes and lithification. Describe
the sources and particle sizes of sedimentary rocks.
Most sedimentary rocks are derived from preexisting rocks, or from
organic materials, such as bone and shell that form limestone, mud
that becomes compacted into shale, and ancient plant remains that
become compacted into coal. The exogenic processes of weathering
and erosion generate the material sediments needed to form these
rocks. Bits and pieces of former rocks—principally quartz, feldspar,
and clay minerals—are eroded and then mechanically transported (by
water, ice, wind, and gravity) to other sites where they are deposited.
In addition, some minerals are dissolved into solution and form
sedimentary deposits by precipitating from those solutions; this is an
important process in the oceanic environment. The cementation,
compaction, and hardening of sediments into sedimentary rocks is
called lithification.
12. Review the history of continental drift, sea-floor
spreading, and the all-inclusive plate tectonics theory. What
was Alfred Wegener's role?
In 1912, German geophysicist and meteorologist Alfred
Wegener publicly presented in a lecture his idea that Earth's
landmasses migrate. His book, Origin of the Continents and
Oceans, appeared in 1915. Wegener today is regarded as
the father of the concept called continental drift. Wegener
postulated that all landmasses were united in one
supercontinent approximately 225 million years ago, during
the Triassic period. The fact that spreading ridges and
subduction zones are areas of earthquake and volcanic
activity provides further evidence for plate tectonics, which
by 1968 had become the all-encompassing term for these
crustal processes.
13. Define upwelling and describe related features on the
ocean floor. Define subduction and explain the process.
The worldwide submarine mountain ranges, called the midocean ridges, were the direct result of upwelling flows of
magma from hot areas in the upper mantle and
asthenosphere. When mantle convection (radiation of heat)
brings magma up to the crust, the crust is fractured and new
seafloor is formed, building the ridges and spreading
laterally. When continental crust and oceanic crust collide,
the heavier ocean floor will dive beneath the lighter
continent, thus forming a descending subduction zone. The
world's oceanic trenches coincide with these subduction
zones and are the deepest features on Earth's surface. This
process resulted in the breakdown of the original super
continent called Pangea into the continents we have today.
(see next slide)
Relative Age of the Oceanic Crust
Figure 11.15
Continents Adrift
Figure 11.16
Earth’s Major Plates
Figure 11.17
14. Characterize the three types of plate boundaries
and the actions associated with each type.
The boundaries where plates meet are clearly dynamic
places. Divergent boundaries are characteristic of seafloor
spreading centers, where upwelling material from the
mantle forms new seafloor, and crustal plates are spread
apart. Convergent boundaries are characteristic of
collision zones, where areas of continental and/or oceanic
crust collide. These are zones of compression. Transform
boundaries occur where plates slide laterally past one
another at right angles to a sea-floor spreading center,
neither diverging nor converging, and usually with no
volcanic eruptions.
15. What is the relation between plate boundaries
and volcanic and earthquake activity?
Plate boundaries are the primary location of Earth's
earthquake and volcanic activity, and the correlation
of these phenomena is an important aspect of plate
tectonics because they are produced by
plate/asthenosphere interactions at these boundaries.
Earthquakes and volcanic activity are discussed in
more detail in the next chapter, but their general
relationship to the tectonic plates is important to
point out here.
End of Chapter 11
Geosystems 5e
An Introduction to Physical Geography
Robert W. Christopherson
Charlie Thomsen
Chapter 12
Tectonics, Earthquakes, and
Volcanism
Geosystems 5e
An Introduction to Physical Geography
Robert W. Christopherson
Charlie Thomsen
Key Learning Concepts:
Describe first, second, and third orders of relief and relate
examples of each from Earth’s major topographic regions.
Describe the several origins of continental crust and define
displaced terrains.
Explain compressional processes and folding; describe four
principal types of faults and their characteristic landforms.
Relate the three types of plate collisions associated with
orogenesis and identify specific examples of each.
Explain the nature of earthquakes, their measurement, and
the nature of faulting.
Distinguish between an effusive and an explosive volcanic
eruption and describe related landforms using specific
examples.
1. How does the ocean floor map (see illustration in
next slide) exhibit the principles of plate tectonics?
The illustration is a representation of Earth with its
blanket of water removed. The scarred ocean floor
is clearly visible, its sea-floor spreading centers
marked by over 64,000 km of oceanic ridges, its
subduction zones indicated by deep oceanic
trenches, and its transform faults stretching at
angles between portions of oceanic ridges.
2. What is meant by an “order of relief”?
Geographers group the landscape's topography into three orders of
relief. These orders classify landscapes by scale, from vast ocean
basins and continents down to local hills and valleys. The first order
of relief consists of continental platforms and oceanic basins.
Examples of first order features would be the Pacific Ocean basin and
the African continent. Intermediate landforms are considered to be
second orders of relief, such as continental masses, mountain masses,
plains and lowlands. A few examples are the Alps, Canadian and
American Rockies, west Siberian lowland, and the Tibetan Plateau. In
ocean basins, second order features include rises, slopes, mid-ocean
ridges, and submarine trenches. Third order features are the most
detailed forms of relief, consisting of individual mountain, cliffs,
valleys and other landforms of smaller size.
3. The difference between relief and topography.
Relief refers to vertical elevation differences in the
landscape, examples include the low relief of
Nebraska and high relief in the Himalayas.
Topography is the term used to describe Earth's
overall relief, its changing surface form, effectively
portrayed on topographic maps.
4. What is a craton? Relate this structure to
continental shields and platforms.
All continents have a nucleus of old crystalline rock
on which the continent grows. Cratons are the
cores, or heartland regions, of the continental crust.
They generally are low in elevation and old
(Precambrian, more than 570 million years in age).
Those regions where various cratons and ancient
mountains are exposed at the surface are called
continental shields. Figure 12-4, shows the principal
areas of shield exposure.
Fig. 12.4: Continental Shields. Portions of major
continental shields that have been exposed by erosion.
Adjacent portions of these shields remain covered.
5. What is a migrating terranes, and how does it add to
the formation of continental masses?
Each of Earth's major plates is actually a collage of many crustal
pieces acquired from a variety of sources. Accretion, or accumulation,
has occurred as crustal fragments of ocean floor, curved chains (or
arcs) of volcanic islands, and other pieces of continental crust have
been swept aboard the edges of continental shields. These migrating
crustal pieces, which have become attached to the plates, are called
terranes. (See example next slide).
(Figure 12-6) At least 25% of
the growth of western North
America can be attributed to
the accretion of terranes since
the early Jurassic period (190
million years ago). A good
example is the Wrangell
Mountains, which lie just east
of Prince William Sound and
the city of Valdez, Alaska.
The Wrangellia terranes–a
former volcanic island arc
and associated marine
sediments from near the
equator–migrated
approximately 10,000 km to
form the Wrangell Mountains
and three other distinct areas
along the western margin of
the continent.
6. Describe the principal types of faults.
Faults are fractures in rocks along which
appreciable displacement has taken place
Sudden movements along faults are the cause of
most earthquakes
Classified by their relative movement which can
be:
Normal faults
Thrust and reverse faults
Strike-slip faults
Types of Faults: (Fig. 12.11)
The San Andreas
Fault System is
an example of
what type of
fault?
A. Normal
B. Thrust
C. Strike
7. Define orogenesis. What is meant by the
birth of mountain chains?
Orogenesis literally means the birth of mountains (oros
comes from the Greek for mountain). An orogeny is a
mountain-building episode that thickens continental crust.
It can occur through large-scale deformation and uplift of
the crust in episodes of continental plate collision such as
the formation of the Himalayan mountains from the
collision of India and Asia. It also may include the capture
of migrating terranes and cementation of them to the
continental margins. Uplift is the final act of the orogenic
cycle. Earth's major chains of folded and faulted mountains,
called orogens, bear a remarkable correlation to the plate
tectonics model.
8. Name some significant orogenies.
Major orogens include: the Rocky Mountains,
produced during the Laramide orogeny (40-80
million years ago); the Appalachians and the Valley
and Ridge Province formed by the Alleghany
orogeny (250-300 million years ago, preceded by at
least two earlier orogenies); and the Alps of Europe
in the Alpine orogeny (20-120 million years ago and
continuing to the present, with many earlier
episodes).
9. How are plate boundaries related to episodes of mountain
building? Explain how different types of plate boundaries
produce differing orogenic episodes and differing
landscapes.
Figure 12-16 illustrates the plate-collision pattern
associated with each type of orogenesis and points
out an actual location on Earth where each
mechanism is operational.
Figure 12-16 Shown in (a) is the
oceanic plate-continental plate
collision type of orogenesis. This
occurred along the Pacific coast of the
Americas and has formed the Andes,
the Sierra of Central America, the
Rockies, and other western mountains.
Shown in (b) is the oceanic plateoceanic plate collision, where two
portions of oceanic crust collide. This
has formed the chains of island arcs
and volcanoes that continue from the
southwestern Pacific to the western
Pacific, the Philippines, and the Kuril
islands. Shown in (c) is the continental
plate-continental plate collision, which
occurs when two large continental
masses collide. Large masses of
continental crust are subjected to
intense folding, faulting, and uplifting.
The collision of India with the
Eurasian landmass produced the
Himalayan Mountains.
10. Explain the nature of earthquakes and
their measurement.
An earthquake is the vibration of Earth produced
by the rapid release of energy
Energy released radiates in all directions from its source,
the focus
Energy is in the form of waves
Sensitive instruments around the world record the event
Earthquake Focus and Epicenter
Earthquakes cont’d
Elastic rebound
Mechanism for earthquakes was first explained by
H. F. Reid
 Rocks
on both sides of an existing fault are deformed by
tectonic forces
 Rocks bend and store elastic energy
 Frictional resistance holding the rocks together is
overcome
 Slippage at the weakest point (the focus) occurs
 Vibrations (earthquakes) occur as the deformed rock
“springs back” to its original shape (elastic rebound)
Foreshocks and aftershocks
Adjustments that follow a major
earthquake often generate smaller
earthquakes called aftershocks
Small earthquakes, called foreshocks,
often precede a major earthquake by days
or, in some cases, by as much as several
years
Seismology
The study of earthquake waves,
seismology, dates back almost 2000 years
to the Chinese
Seismographs, instruments that record
seismic waves
Record the movement of Earth in relation
to a stationary mass on a rotating drum or
magnetic tape
Seismology
Two Types of seismic waves:
Primary (P) waves
Push-pull (compress and expand) motion,
changing the volume of the intervening
material. Travel through solids, liquids, and
gases
Secondary (S) waves
“Shake” motion at right angles to their
direction of travel. Travel only through
solids. Slower velocity than P waves
Measuring the Size of Earthquakes:
Two measurements that describe the size of an
earthquake are:
Intensity—A measure of the degree of earthquake
shaking at a given locale based on the amount of
damage
Magnitude—Estimates the amount of energy
released at the source of the earthquake
Measuring the Size of Earthquakes:
Magnitude scales
Richter magnitude—Concept introduced by Charles
Richter in 1935
Richter scale
 Based
on the amplitude of the largest seismic wave
recorded
 Accounts for the decrease in wave amplitude with
increased distance
 Magnitudes less than 2.0 are not felt by humans
 Each unit of Richter magnitude increase corresponds to
a tenfold increase in wave amplitude and a
32-fold energy increase
Earthquake Destruction
Liquefaction of the ground
Unconsolidated materials saturated with
water turn into a mobile fluid
Tsunamis, or seismic sea waves
Destructive waves that are often are also
called “tidal waves”
Earthquake Destruction
Tsunamis, or seismic sea waves
Result from vertical displacement along a
fault located on the ocean floor or a large
undersea landslide triggered by an
earthquake
In the open ocean height is usually < 1
meter
In shallower coastal waters the water piles
up to heights over 30 meters
Formation of a Tsunami
11. What is a volcano? Describe some related features.
A volcano forms at the end of a central vent or pipe that
rises from the asthenosphere through the crust into the
volcanic mountain, usually forming a crater, or circular
surface depression at the summit. Magma rises and collects
in a magma chamber deep below the volcano until
conditions are right for an eruption. Other features related
to volcanic activity are; calderas, large basin-shaped
depressions formed when summit material on a volcanic
mountain collapses inward after eruption or loss of magma;
cinder cones, small cone-shaped hills with a truncated top
formed from cinders that accumulate during moderately
explosive eruptions; and, shield volcanoes, that are created
by effusive volcanism, similar in shape to a shield of armor
lying face up on the ground.
12. Where do you find volcanoes in the world and Why?
The location of volcanic mountains on Earth is a
function of plate tectonics and hot spot activity.
Volcanic activity occurs in three areas: along
subduction boundaries at continental plate-oceanic
plate or oceanic plate-oceanic plate convergence;
along sea-floor spreading centers on the ocean floor
and areas of rifting on continental plates; and at hot
spots (like Hawaii), where individual plumes of
magma rise through the crust.
13. Compare effusive and explosive eruptions. Why
are they different?
Effusive eruptions are the relatively gentle eruptions that produce enormous
volumes of lava on the seafloor and in places like Hawaii. Direct eruptions
from the asthenosphere produce a low-viscosity magma that is very fluid. A
typical mountain landform built from effusive eruptions is gently sloped,
gradually rising from the surrounding landscape to a summit crater, similar
in outline to a shield of armor lying face up on the ground, and is therefore
called a shield volcano.
Volcanic activity along subduction zones produces the well-known explosive
volcanoes. Magma produced by the melting of subducted oceanic plate and
other materials is thicker than magma from effusive volcanoes.
Consequently, it tends to block the magma conduit inside the volcano,
allowing pressure to build and leading to an explosive eruption. The term
composite volcano, is used to describe explosively formed mountains.
Composite volcanoes tend to have steep sides and are more conical than
shield volcanoes, and therefore they are also known as composite cones.
Fig. 12.32: Shield and Composite Volcanoes
Composite Volcanoes
Figure 12.34
End of Chapter 12
Geosystems 5e
An Introduction to Physical Geography
Robert W. Christopherson
Charlie Thomsen
Physiographic Regions of
Canada
Geomorphology: A Canadian Perspective
By: Alan S. Trenhaile
*Review Chapter 2 (on reserve at the Map
Library)
Physiographic Regions of Canada
Geographers define a physiographic region as a large land area with a shared geological structure and
history. The oldest and largest of Canada’s seven major physiographic regions, the Canadian Shield,
was formed about three million years ago. The youngest region, the Hudson Bay Lowlands, has been
formed over the last 7,000 years.
The Geological Evolution of Canada
Modern Canada is the product of three
major geological developments:
1. The formation of the Canadian Shield
2. The formation of mountains (orogenesis)
from sediments that accumulated in basins
around the margins of the Shield
3. The deposition of sediments in shallow
seas in the intervening areas.
Canadian Shield
The ancient Precambrian crystalline rocks of the shield
occupy nearly half the country. This surface can be
compared to an inverted military shield (more or less like a
saucer), descending outwards from a flat, slightly depressed
center which is occupied by Hudson Bay.
The Canadian Shield has two major landforms, a rocky
surface of mainly igneous rock and many coniferous forests.
The highest elevation of the Canadian Shield is only about
500m above sea level. The rocky surfaces are the result of
weathering; water, freeze thaw and fluvial erosion the
mountains have eroded into hard even land. The southern
section of the Canadian Shield is mainly boreal or
coniferous forests. In the northern part it is had rocky frozen
tundra.
Canada's three highland areas lie north, east and west of the shield
and lowland areas. Each one is different as they each are formed
differently and have different pasts
#1. The Cordillera is the mountainous region of western
Canada. This region includes most of British Columbia, the
Yukon, and southwest Alberta. Long chains of high, rugged
mountains stretch from north to south including the Rocky
Mountains on the east side and the Coastal Mountains near
the ocean. The interior of B.C. is between the mountain
ranges and is suitable for ranching and agriculture.
The Cordillera is a crustal collage of at least 6 major and
many smaller terranes, including large blocks of oceanic
crust, volcanic arc material, and fragments of unknown
continental margins.
#2. The Appalachian Highlands
The area in question is located in all of the 4
maritime provinces ( New Brunswick, Nova
Scotia, Prince Edward Island, and Newfoundland
and Labrador) as well as the majority of the area
know as the Gaspe Peninsula or “thumb” of
Quebec. The Appalachian Mountains formed
approximately 300 million years ago, near the end
of the Paleozoic Era when the sedimentary rock
layers were uplifted and folded. These mountains
were high and had jagged peaks. Erosion has
reduced them to rolling mountains and hills.
#3. Innutian Mountain System (Canadian Arctic)
In the Canada's far north, the Innutian Mountains some are over 3,000 meters in height. These
mountains were constructed during the Mesozoic
Era. They are much younger than the Appalachians,
and the erosion has not yet have had effect on them.
These mountains support no vegetation.
Lowlands:
1.
2.
3.
Great (Interior) Plains
Hudson Bay Region
Great Lakes and St. Lawrence Region
#1. Interior Plains
The Interior Plains is in between the Cordillera
and the Canadian Shield. It is found in the Yukon,
Northwest Territories, British Columbia, Alberta,
Saskatchewan and Manitoba. It is also called the
Interior Plains the Prairie Provinces or just the
Prairies. The term prairie refers to the prairie
grasses that grow wild in Alberta, Saskatchewan
and Manitoba. The entire region is generally flat in
elevation.
#2. Hudson Bay Region
The south-western shore of the Hudson Bay
- James Bay is a very flat, low area which is
covered by swampy forest. During the last
ice age, the waters of the Hudson Bay
covered this are. Known as the Hudson Bay
Lowlands this region has a layer of
sedimentary rock which covers the ancient
rock layer of Canadian Shield.
#3. GREAT LAKES-ST. LAWRENCE
Located to the south of the Canadian Shield, the Great Lakes-St.
Lawrence Lowlands, are comprised of two major parts. The two
areas, suggested by the name, are divided a little wedge of the
Canadian Shield near Kingston, Ontario. The bedrock of these
lowlands are made of the similar material as that of the interior
plains - sedimentary rock. They were formed in the Paleozoic Era.
The Great Lakes Lowlands were formed by the effects of
glaciation. The region is a rolling landscape where flat plains are
interrupted with glacial hills and deep river valleys. After the
glacial period the lakes were much larger than they are today. The
shrinking of the lakes left flat plains of sediments. These
sediments formed excellent soil for farming.
End of Presentation
Movie:
Mountain Building
This program erodes the myth of the mountain as a
solid, permanent structure. Animations are used to
illustrate the process of orogeny (mountain building)
through accretion and erosion, as well as the role of
plate tectonics, the rock cycle, and how different
types of rock are formed in the course of mountain
building.