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Land Form Patterns
Introductory Lesson
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Topography is a general term referring to the surface features of the
earth like, hills, mountains, valleys, plains, plateaus and other relief
features. Your book defines it as " the natural and human features of
the earth's surface". The map to the right shows the topographical
features of South America.
Hills are typically defined as areas of upward relief less than 300 600M.
Mountains are defined as areas of upward relief greater than 300600M. It is important to note that books differ on the actual relief
required for a hill to be a mountain but the difference is one of the
degree of elevation. See if you can find a contradiction in your own
book!!
Plains are areas of flat land with very little relief. They are found at
low elevations often along coasts and in the center of continents.
Plateaus are areas of flat land with little relief. They occur at high
elevations and are associated with mountains. Like hills and mountains
plains and plateaus differ based on elevation.
Assigned Readings
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"Structures on Earth's Surface" pp 6-7 in your text book.
Assigned Activities
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Open, print and complete "Active Learning Lesson #1".
Test Yourself
1. Observing the elevation profile below which province would be least
likely to have extensive plains.
2. Imagine you flew from the west coast of South America to the east
coast and you flew right along the equator. What land forms would you
fly over?
3. ___?___ is a general term referring to the lye of the land.
4. Hills are typically defined as areas of upward relief less than
___?___m.
5. Mountains are defined as areas of upward relief greater than
___?___m.
6. Plains are areas of flat land with very little relief. They are found at
___?___ elevations often along coasts and in the center of continents.
7. Plateaus are areas of flat land with little relief. They occur at ___?___
elevations and are associated with mountains.
Test Yourself Answers
1. Observing the elevation profile below which province would be least
likely to have extensive plains.
With its abundance of mountains British Columbia seems like the least
likely place to have plains which occur at low latitudes. Having said
that, this profile is one cross section of British Columbia and there may
be other latitudes where there are plains especially along the coast.
2. Imagine you flew from the west coast of South America to the east
coast and you flew right along the equator. What land forms would you
fly over?
You would fly over Plateaus, Mountains and then Plains.
3. Topography: is a general term referring to the lye of the land.
4. Hills are typically defined as areas of upward relief less than 300600m.
5. Mountains are defined as areas of upward relief greater than 300600m.
6. Plains are areas of flat land with very little relief. They are found at
lower elevations often along coasts and in the center of continents.
7. Plateaus are areas of flat land with little relief. They occur at higher
elevations and are associated with mountains.
Land Form Patterns
Have a look at the map below to see where the world's major mountain
ranges lie. Is there a pattern to these mountain ranges? You may be able to
see other patterns. Later in this section we will explain the reason for these
patterns.
Can you identify the "Rockies in North America", the "Andes in South
America", and the "Himalayas in Asia" on the map?
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Most mountains and high elevations are located on coasts of
continents.
Large mountain ranges occur along the west coast of North and South
America. This is quite evident in the relief image.
What is not evident is that major mountain ranges coincide with "tectonic
plate boundaries". You may or may not be familiar with tectonic plates. That
concept will be covered Later in this section. In any event by clicking on the
map below you can see that the plate boundaries coincide with the major
world mountain ranges.
Test Yourself
1. Which topographical feature do you find along the west coast of North
and South America?
2. When a continent contains a mountain range, on which part of the
continent is it usually found?
3. The boundaries between tectonic plates often coincide with which type
of topographical feature?
Earth's Interior
The earth's interior is neither all
solid nor is it all molten. There
are layers with a different
density, thickness and
composition.
Furthermore the earth's crust is
not one continuous layer. It is
broken into many sections known
as plates. Some plates are quite
small while others are quite
large. They all float and move on
top of the molten asthenosphere.
When they push together and
when they pull apart they create
"tectonic forces". It is interesting to note; without this liquid layer called the
asthenosphere we would not experience earthquakes or volcanoes.
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Inner Core: The deepest part of the earth (1512 miles deep) is a solid
that contains both iron and nickel. It is because of this that the centre
of the earth is a magnet, a compass. It generates a magnetic field that
protects the earth from flying out of orbit.
Outer Core: Outside of the inner core lays the outer core (1419 miles
deep). This is much like the inner core with the exception that it is a
liquid that contains sulphur and oxygen (which lowers the melting
point).
Mantle: Occupying 1789 miles of the earth is the magma (iron and
magnesium) that makes up the mantle. It is mostly solid except the
outer 200-300 Km which is extremely hot and goopy; very plasticlike. This outermost liquid layer of the mantle is referred to as the
asthenosphere.
Mohorovicic Discontinuity: Boundary between the mantle
(asthenosphere) and the Lithosphere.
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Lithosphere (crust): This is the top layer of the earth, which is
basically hardened mantle (magma). It contains two segments, the
oceanic and continental crusts. Note: this is the same crust, it just
depends how thick it is to determine if it is part of the Oceanic or
Continental Crust. For instance, if you drained all of the water from
earth, then there would be one, giant Continental Crust. Likewise, if
you flooded everything, you'd have one, giant Oceanic Crust.
Assigned Readings
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"The Structure of Earth" p. 4-6
Assigned Activities
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Complete question #3 both part "a" and "b". Share your answer with
the class.
Plate Tectonics
Explaining Compressional and Tensional tectonic Forces:
Tectonic plates move or float on top of the asthenosphere (orange in the
figure). However they do not float freely. The plates are forced in specific
directions by the flow of magma beneath. Just like a boat caught in a current
plates move with the flow of magma. The magma forms convectional
currents. The magma closer to the core heats and then rises towards the
surface as its density decreases. Once the rising magma reaches the
lithosphere it moves in opposite directions.
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Compressional Forces occur where two tectonic plates come
together. They compress against each other.
Subduction Zones sometimes occur where compressional forces
result from two plates colliding.
Tensional Forces occur where two tectonic plates are pushed apart.
The tension is created as the plates move away from each other.
Ridge Zones sometimes occur where two plates move apart. The
magma rises between the plates and forms a ridge.
Reading a Tectonic Plates Map
The map below is similar to the one on p. 12 of your text.
Notice that subduction zones occur where the tectonic plates are moving
towards each other while Ridge zones occur where the plates are moving
apart.
Notice that the Americas (North American Plate and South American Plate)
are moving away from Europe and Africa (Eurasian Plate and African Plate.
The Developer
Alfred Wegener was one of the first to propose the theory of continental drift.
While pondering the similarities between the coastlines of South America and
Africa, Wegener came up with an idea: What if the continents were once all
connected and just drifted over the years? It is this German man to whom
we credit with the proposal of the theory of Continental Drift.
The Evidence
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Ferns and Reptiles in many different continents
Glaciers that were then tropical forests
Same types of rocks on continents close to each other (yet separated
by an ocean)
The coastlines of Africa and South America
The Flaw in Wegener's Theory
However, there was one major flaw in Wegener's theory of continental
plates. He thought that each of the continents were a separate plate--they
were just drifting on a never-changing ocean.
The Canadian Correction
J. Tuzo Wilson was the 1960’s Canadian scientist who resurrected Wegner’s
theory after years of disbelief by the science community.
Today, we know that that's false, thanks to the discovery of crustal plates.
The plates of the earth are not composed of just land; they're composed of
ocean, too. In some cases, the plates are just land, in others they're just
ocean, and, in still other cases, they consist of land and ocean. They each
have different boundaries and move in all different directions.
Continental Drift
It refers to the movement of the more than 20 plates (9 major) due to
convergent, divergent, and transform boundaries. The continents drift at a
rate of 2 inches a year, or, as fast as a fingernail grows. It is believed to
have started 200 million years ago. The original single continent was named
Pangaea and the original ocean that surrounded the land was called
Panthalasa. Figure1.8 on p. 10 of your book shows the process of the
continents moving apart. View the animation above to see an approximation
of how continental drift might have occurred
Assigned Readings
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page 10-12 of your book
Test yourself
1. In the figure above which letter is located at a ridge zone.
2. In the figure above which letter is located at a subduction zone.
3. In the figure above which letter is located where some of the earth's
crust is melting back into magma?
4. In the figure above which letter is located at a point where a volcano
might occur?
5. In the figure above what color is the asthenosphere.
6. In the figure above which letter is located at a point where
compressional forces might occur?
7. In the figure above which letter is located at a point where tensional
forces might occur?
8. In the figure above which letter is located at a point where new crust
is forming?
9. When you read about Wegener and the theory of continental drift you
saw the terms converging plates. Do you think the border between
converging plates coincides with any term we have used this lesson?
10.When you read about Wegener and the theory of continental drift you
saw the terms diverging plates. Do you think the border between
diverging plates coincides with any term we have used this lesson?
Plate Tectonics Lab
Major Mountain ranges tend to coincide with subduction zones at the
boundaries between two converging plates. The tremendous compressional
forces literally fold the thin crust in to mountains. Remember this occurs over
millions of years.
Volcanoes can occur at subduction zones or at ridge zones. At subduction
zones the compressional forces sometimes leave a crack in the crust that
allows the magma to reach the surface. At ridge zones the plates are moving
apart which allows magma to reach the surface from the asthenosphere.
Because of the excessive number of active volcanoes on the coast around the
pacific ocean it is known as the Pacific Ring of Fire.
Earthquakes often occur at transform zones where the plates are moving
beside each other instead of toward or away from each other. Look Closely at
figure 1.10 on page 12 and you can see transform zones where the plates
are moving side by side.
Notice that subduction zones occur where the tectonic plates are moving
towards each other while Ridge zones occur where the plates are moving
apart and transform zones occur where plates are moving side by side.
Notice that the Americas (North American Plate and South American Plate)
are moving away from Europe and Africa (Eurasian Plate and African Plate.
Assigned Activities
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Get an atlas and some coloured pencil leads.
Click on "Tectonic Plates Lab" open it, print it and complete it.
Folded Mountains
Most Major Mountain ranges were
formed by folding.
The collision of continental plates
causes the thin crust
(lithosphere) to bend.
For example the Appalachian
mountains and the atlas
mountains were formed by
folding when North America and
Africa collided 400 million years
ago.
All rock that is put under extreme pressure for long periods of time
(thousands or millions of years) will fold like clay. Folding is a process in
which the Earth's plates are pushed together in a roller coaster like series of
high points and low points. Folding bends many layers of rocks without
breaking them. The peaks are known as anticlines while the valleys are
known as synclines.
Test yourself
1.
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4.
5.
6.
What type of tectonic force is required to create folded mountains?
What name is given to the peaks created in folded mountains?
What term is given to the valleys created in folded mountains?
Are many of the worlds mountains formed by folding?
How long does it take for folded mountains to form?
At which type of tectonic zone would you find folded mountains?
(ridge, transform or subduction)
Tectonic Faults
Fault lines are great cracks in the crust.
Mountains Formed by Normal Faults
Normal Faults are caused by tensional forces. When the land moves apart at
a fault line one plate drops down lower that the other.
Mountains Formed by Reverse Faults
Reverse faults are caused by compressional forces where plates move
together at the fault. The land that rises above can form a mountain.
Fault Block Mountains
Fault Block Mountains sometimes form when many layers of the Earth's crust
are moved vertically upward between two parallel fault lines. Vertical force is
caused by the earth's internal pressure. The mountains that are formed in
this way are called fault-block mountains. The Sierra Nevada mountains in
California and Nevada, and the Grand Teton range of Wyoming are examples
of fault-block mountains.
Overthrust Faults
Overthrust Faults are caused by compressional forces where plates move
together at the fault. They are a class of reverse faults that have had folding
occur before the faultformed.
Assigned Readings
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"Mountains Formed by Volcanoes" on page 14 of your text.
Volcanic Mountains
Volcano is an opening in the earth's crust through which magma, gasses, and
ash erupt. The shape of the volcano depends on the thickness of lava. Most
volcanoes occur on plate boundaries.
Three Types of Volcanoes
Ash and Cinder cones are the
simplest type of volcano. They
are built from particles and blobs
of congealed lava ejected from a
single vent. As the gas-charged
lava is blown violently into the
air, it breaks into small fragments
that solidify and fall as cinders
around the vent to form a circular
or oval cone. Most cinder cones
have a bowl-shaped crater at the summit and rarely rise more than a
thousand feet or so above their surroundings. Cinder cones are numerous in
western North America as well as throughout other volcanic terrains of the
world. They are very explosive because the lava is very thick and slow
flowing. It blocks the vent causing pressure to build up to high levels before
it finally blows.
Shield volcanoes built almost
entirely of fluid lava flows. Flow
after flow pours out in all
directions from a central summit
vent, or group of vents, building
a broad, gently sloping cone of
flat, domical shape, with a profile
much like that of a warrior's
shield. They are built up slowly
by the accretion of thousands of highly fluid lava flows called basalt lava that
spread widely over great distances, and then cool as thin, gently dipping
sheets. These are the least explosive because the lava is so thin and fluid
that it does not block the vent
and prevents pressure build up.
Composite volcanoes have a
conduit system through which
magma, from a reservoir deep in
the earth's crust, rises to the
surface. The volcano is built up
by the accumulation of material
erupted through the conduit and
increases in size as lava, cinders, ash, etc., are added to its slopes. The lava
varies causing it to be explosive one time while the next time it can be gentle
flowing.
Assigned Readings
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"Mountains formed by volcanoes" on page 14 of your book.
Assigned Activities
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Complete Questions #14 and 15 on p.16 of your text. Share your
answers with the class.
Test yourself
1. Which type of volcano is most explosive?
2. Which type of volcano is least explosive?
3. Which type of volcano is explosive at times and slow flowing lava at
times?
4. Which type of volcano has the thickest lava?
5. Which type of volcano has the thinnest, most liquid lava?
6. Which type of volcano often has side vents?
7. Which type of volcano has the gentlest slope?
8. Which type of volcano is steepest? Ash & Cinder
9. What term is given to the opening of a volcano?
10.Liquid, fluid, melted rock below the earth's surface is known as:
11.Liquid, fluid, melted rock that reaches the earth's surface is known as:
Answers
1. Which type of volcano is most explosive? Ash & Cinder
2. Which type of volcano is least explosive? Shield
3. Which type of volcano is explosive at times and slow flowing lava at
times? Composite
4. Which type of volcano has the thickest lava? Ash & Cinder
5. Which type of volcano has the thinnest, most liquid lava? Shield
6. Which type of volcano often has side vents? Composite
7. Which type of volcano has the gentlest slope? Shield
8. Which type of volcano is steepest? Ash & Cinder
9. What term is given to the opening of a volcano? Crater
10.Liquid, fluid, melted rock below the earth's surface is known as:
Magma
11.Liquid, fluid, melted rock that reaches the earth's surface is known as:
Lava
Assigned Activities
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Click on "Mountains Lab" open it and complete the lab.
Weathering
Physical Weathering
Weathering vs. Erosion
Weathering is the breakdown of rock and minerals.
Erosion is a two-part process that starts with (1) breakdown of land
(weathering) and also includes the movement (transportation) of these
weathered materials and is followed by (2) Deposition of the eroded
material occurs when it is dropped in a new location.
Denudation is a term that refers to the wearing down or smoothing off of
land features. The processes of weathering and erosion are denudational.
They are also gradational because they grade the earth’s surface.
Physical Weathering vs. Chemical Weathering
Physical weathering is the breakdown of rock and minerals by mechanical
stress whereas chemical weathering breaks down rock with chemical
reactions often including water.
Types of Physical Weathering
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Frost fracture: the expansion of freezing water that causes rocks to
crack.
Heat expansion: rocks can expand and subsequently fracture.
Plant growth: expansion due to root growth as shown in the picture
below.
Burrowing animals: tunnelling animals can increase the size of
existing cracks
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Exfoliation: as internal pressure is released from certain rocks, it can
cause layers to split and fall off.
Environment's Affect on Physical Weathering
Fast temperature changes like occur in the desert increases the amount of
physical weathering due to heat expansion. Conversely, regions like the
tropics where there is little temperature change the amount of physical
wreathing due to heat expansion is minimal.
Abundant precipitation combined with alternating freezing/thawing
temperatures increases the amount of frost fracture. Conversely, the
absence of those climatic conditions reduces the amount of frost fracture.
Running water increases physical erosion as friction occurs between water
and rock.
Ocean waves cause hydraulic pressure and abrasion on the shore leading to
physical weathering.
Assigned Readings
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"Weathering" on page 23-24 of your text.
Test yourself
1. The term that refers to the break down of rocks and minerals.
2. The term that refers to the breakdown, transportation and deposition
of rock and mineral.
3. Weathering that relies on mechanical processes/forces to break down
rock and mineral.
4. Weathering that relies on chemical processes to break down rock and
mineral.
5. Physical weathering that that causes rocks to break off due to internal
pressure.
6. Physical weathering that that causes rocks to break due to freezing
water expanding in rock cracks.
7. Physical weathering that that causes rocks to break due to fast
changes in temperature
Answers
1. The term that refers to the break down of rocks and minerals.
EROSION
2. The term that refers to the breakdown, transportation and deposition
of rock and mineral. WEATHERING
3. Weathering that relies on mechanical processes/forces to break down
rock and mineral. PHYSICAL WEATHERING
4. Weathering that relies on chemical processes to break down rock and
mineral. CHEMICAL WEATHERING
5. Physical weathering that that causes rocks to break off due to internal
pressure. EXFOLIATION
6. Physical weathering that that causes rocks to break due to freezing
water expanding in rock cracks. FROST FRACTURE
7. Physical weathering that that causes rocks to break due to fast
changes in temperature. HEAT EXPANSION
Chemical Weathering
Types of Chemical Weathering
Chemical weathering is the breakdown of rocks and minerals by chemical
reactions and usually involves the action of rainwater.
There are three different types of chemical weathering described below.
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The formation of solutions as rainwater absorbs CO2 , SO2, and other
chemicals from the atmosphere along with organic acids from the soil
which then reacts with rock and minerals causing some to dissolve and
move away.
Hydrolysis, like the first process, involves the minerals in solution. In
this case, carbonic acid reacts with silicates in some rocks leaving a
soft clay from which potassium, sodium and magnesium are
subsequently leached.
Oxidation is the reaction of metallic minerals to oxygen (mainly in
water). This results in the formation of oxides, which tend to be softer
than the original mineral. For example, rust on iron.
How Environmental Conditions Affect Chemical Weathering
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Heavy rain, running water and abundance of water increases the
amount of dissolving that occurs. Conversely less abundance of water
leads to less dissolving.
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High temperatures will increase the rate of chemical reactions. It is a
fact of chemistry that heat increases the speed of many reactions like
oxidation.
Ocean water contains salt which can increase the rate of many
reactions like oxidation.
Assigned Readings
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"Chemical Weathering" on page 24-25 in your text book.
Assigned Activities
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Click on "Weathering active learning lesson" , open it, print it and
complete it.
Test yourself
1. Which type of chemical weathering involves organic acids dissolving
minerals allowing them to move away from the parent rock?
2. Which type of chemical weathering involves organic acids dissolving
silicate causing the formation of soft clay which can easily be leached
away?
3. Which type of chemical weathering involves the formation of oxides,
often in the presence of water, which tend to be softer than the
original mineral?
4. What affect would high ambient temperature have on the rate of
chemical weathering?
5. What affect would an extreme lack of water, like desert conditions,
have on the rate of chemical weathering?
6. What affect would heavy wind have on the rate of chemical reactions?
7. How does the presence of ocean water affect the rate of chemical
weathering?
Answers
1. Which type of chemical weathering involves organic acids dissolving
minerals allowing them to move away from the parent rock?
FORMATION OF SOLUTIONS
2. Which type of chemical weathering involves organic acids dissolving
silicate causing the formation of soft clay which can easily be leached
away? HYDROLYSIS
3. Which type of chemical weathering involves the formation of oxides,
often in the presence of water, which tend to be softer than the
original mineral? OXIDATION
4. What affect would high ambient temperature have on the rate of
chemical weathering? INCREASE CHEMICAL WEATHERING
5. What affect would an extreme lack of water, like desert conditions,
have on the rate of chemical weathering? DECREASE CHEMICAL
WEATHERING
6. What affect would heavy wind have on the rate of chemical reactions?
NO AFFECT UNLESS IT HAS AN AFFECT ON TEMPERATURE OR
PRECIPITATION
7. How does the presence of ocean water affect the rate of chemical
weathering? INCREASE CHEMICAL WEATHERING
Erosion and Running Water
River Life Cycle
Drainage Basins
Drainage Basin is the area of land drained by a river and its tributaries.
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The Amazon Basin, is the planet's largest body of fresh water with
1100 tributaries 17 of which are more than 1000 miles long. Many of
the tributaries begin in Colombia and Peru.
The Nile river, in Africa is the longest river in the world
Rivers change over time and seem to go through three stages:
1. Youth
2. Maturity
3. Old Age
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Youth (figure 2.7 p.28)
o Are usually found in highland or mountain regions.
o They tend to have a steep slope (high gradient)
o Usually have a small volume of water
They have a rapid flow of water
There is usually very rapid erosion especially vertically
A narrow “V” shaped valley is characteristic
Water falls and rapids are common
Maturity (figure 2.7 p.28)
o
Most high relief is eroded
o Gentler slope
o Many well developed tributaries
o Broad flat river valley
o Well developed flood plain
o More lateral erosion than vertical
o Meandering results
Late Maturity (figure 2.7 p.28)
o Remember the stages are not distinct.
o These changes occur over long periods of time.
Old Age (figure 2.7 p.28)
o Almost no slope
o Very little relief
o Elaborate meandering
o Oxbow lakes develop
o Often swampy areas around river
o Very muddy due to slow speed
o Most susceptible to flooding because of large flood plain.
o
o
o
o
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Evaluating Evidence to Determine the Age of Rivers
There are six common pieces of evidence you can look for to determine the
stage of a river.
1.
2.
3.
4.
5.
6.
Slope of the river (steeper = younger)
Relief of the banks (steeper = younger)
Width of the valley (wider = older)
Meandering (more = older)
Size of flood plain (wider = older)
Rapids or water falls (more = younger)
Two Directions of River Erosion
1. Vertical erosion makes rivers deeper as is the case in young rivers
2. Lateral erosion makes rivers wider leading to the meandering of
mature rivers.
Assigned Readings
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"Rivers as Agents of Erosion" on pages 25-28 of your text book.
Assigned Activities
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Click on "River active learning lesson" open it, and complete it.
Test yourself
1. What term is given to the land area that is drained by a river and its
tributaries?
2. What river is depicted in the map to the right?
3. The red river meanders along with a slow flow rate. It floods
frequently. What stage do you think it is in?
4. River "X" is a very fast flowing river with lots of rapids. It is a favourite
site for X-Games enthusiasts who like to "run the rapids" in kayaks.
What stage is this river in?
5. When a river digs deep down into the river-bed what type of erosion is
occurring?
6. When a slow moving meandering river gouges out the sides of the
river at the turns which type of river erosion is occurring?
7. Which stage of river has the steepest sides?
8. Which stage of river has the most meandering?
9. Which stage of river has the fastest flowing water?
10.Which stage of river has oxbow lakes associated with it?
11.Which stage of river has a broad flat flood plain?
12.Which stage of river is usually associated with mountains?
13.Which stage of river has a V-shaped valley?
14.Which type of erosion is very common in youthful rivers?
15.Which type of erosion is very common in old rivers?
Test yourself
1. What term is given to the land area that is drained by a river and its
tributaries? DRAINAGE BASIN
2. What river is depicted in the map to the right? NILE
3. The red river meanders along with a slow flow rate. It floods
frequently. What stage do you think it is in? OLD AGE
4. River "X" is a very fast flowing river with lots of rapids. It is a favourite
site for X-Games enthusiasts who like to "run the rapids" in kayaks.
What stage is this river in? YOUTHFUL
5. When a river digs deep down into the river-bed what type of erosion is
occurring? VERTICAL
6. When a slow moving meandering river gouges out the sides of the
river at the turns which type of river erosion is occurring?
HORIZONTAL
7. Which stage of river has the steepest sides? YOUTHFUL
8. Which stage of river has the most meandering? OLD AGE
9. Which
10.Which
11.Which
12.Which
13.Which
14.Which
15.Which
stage of river has the fastest flowing water? YOUTHFUL
stage of river has oxbow lakes associated with it? OLD AGE
stage of river has a broad flat flood plain? OLD AGE
stage of river is usually associated with mountains? YOUTHFUL
stage of river has a V-shaped valley? YOUTHFUL
type of erosion is very common in youthful rivers? VERTICAL
type of erosion is very common in old rivers? HORIZONTAL
River Deltas
Delta is a low lying area at mouth of river formed by deposition of silt
deposition occurs because river slows as it enters ocean or lake. There are
three types, arcuate, digitate and
estuarine.
Arcuate Delta:
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Digitate Delta:
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From Latin for finger
Delta with long fingers of
sediment reaching into the
sea
Named from Latin word for curved in
the shape of a bow.
Fan shaped
The Nile Delta depicted on p. 32 of
your text is a good example
To the right is a satellite photo of the
Nile Delta, notice the fan shape on
the right-hand side of the mount of
the river.
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The Mississippi Delta is a good example depicted on p. 32.
To the right is a satellite photo of the Mississippi Delta, notice that it
runs out into the Gulf of Mexico like a finger - unlike the Nile Delta
above.
Estuarine Delta:
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Formed when river runs
into a bay or estuary
Tidal mud flats form which
can be seen at low tide
Sediment deposited from
river outflow and from
Tidal inflow
The Seine River Delta
depicted in figure 2.12 on
p. 32 of your book is a
good example.
To the right is a satellite
photo of the Amazon
Delta, notice the tidal flats
or islands that cover and
uncover with the tide.
This picture below shows a small estuarine delta in Notre Dame Bay.
Assigned Readings

"Erosion and Deposition Process" on page 30-32 of your text.
Test yourself
1. The term given to the low lying land at the mouth of a river. Silt is
deposited there.
2. The term given to a fan shaped delta.
3. The name give to a finger shaped delta
4. The name given to a delta that forms in a bay or estuary.
5. Why does so much deposition occur at the delta of a river?
Answers
1. The term given to the low lying land at the mouth of a river. Silt is
deposited there. DELTA
2. The term given to a fan shaped delta. ARCUATE
3. The name give to a finger shaped delta DIGITATE
4. The name given to a delta that forms in a bay or estuary. ESTUARINE
5. Why does so much deposition occur at the delta of a river? THE FLOW
RATE SLOWS BECAUSE THE WATER ENTERS A LAKE OR OCEAN> THE
SLOWER MOVING WATER DROPS THE SILT
Red River Case
The lion's share of this lesson is actually doing the case study as is outlined
in "activities". However you should take some time to consider the following
questions. They are not intended to have you to write an answer, rather they
are intended to make you ponder "social issues". This is a social studies
course and during its course of study you will be challenged to think about
social issues.
Many of the case studies you will do in this course will help you prepare for
the case study questions on the public exam. However they have a much
greater significance than that short term objective.
In ten years time when you are raising your family and working in the peak
of your productivity, you may forget the book definition of hydrolysis or of
arcuate delta, but you will have to take stances on social and environmental
issues. It might be at voting time and an environmental issue is on the table.
You might be part of a company trying to solve problems in regions affected
by volcanoes or floods. The issues that arise in case studies are real life
issues that you will be dealing with in your life ahead of you. You may not
deal with a flood as we will look at there but you have to deal with a freezing
rain storm or a forest fire. Take some time to ponder the questions below.
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Do we need to change they way we treat the environment?
Should we change the way we have always done things to reduce the
harm to the environment.
Do governments have the right to tell people they can not live in flood
prone areas.
When solving problems or addressing issues are many heads
(partnerships) better than one.
Who should have to pay for clean-up after a disaster?
When solving complicated problems like protecting Winnipeg from a
looming flood is only one best way?
Assigned Readings

"CASE STUDY the Red Rive Flood" on pages 29-30 of your text book.
Assigned Activities

Complete question #7 in its entirety. Part a and part d have two
questions within them. Make sure you answer both.
Erosion and Glaciers
Continental Glaciers
Continental Glaciers vs. Alpine glaciers
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Continental glaciers cover parts of continental land masses like
Greenland;
Alpine glaciers are found high in mountain valleys, above the snowline.
Differences:
o Location; Alpine glaciers are only found on mountain tops
whereas continental glaciers are only found at the earth's poles
regardless of elevation.
o Size; Alpine glaciers are smaller compared to Continental
glaciers.
Similarities:
o Both move and cause erosion
o Both change the landscape
o Both developed in constantly cold temperatures below freezing.
o Figure 2.13 on page 34 of your text shows a continental glacier
and the the land forms it creates through weathering and
deposition.
Features of Continental Glaciation
Outwash plain:
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like a river Delta;
meltwater flowing from a glacier deposits silt like river deltas;
silt is deposited in layers;
small particles are carried further away;
larger particles drop closer to the glacier.
Terminal Moraine:
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heap or ridge of bulldozed gravel that marks the end of the forward
motion of a glacier;
as a glacier retreats it deposits debris/gravel.
Erratics:
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large boulders that were transported long distances and dropped;
they now sit in a region and look very much out-of-place.
Drumlins:
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egg shaped hill;
formed under glaciers;
sloped or pointy end points in direction of ice flow;
formation
o ice melts under glacier
o deposits of gravel are made
o glacier moves forward
o deposits are bull-dozed along and catch up in rough areas
forming piles or drumlins.
Eskers:
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long deposits of eroded glacial material;
formed by sub-glacial streams that deposit material like all rivers;
sometimes known as Highways of the North because they are good for
traveling on with ATV's.
Evidence for Direction of Glacier Movement
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The gently-sloped end of drumlins point in the direction of glacier
movement.
The terminal moraine marks the furthest extent of the glacier.
The layers of silt in an outwash plain can indicate direction of glacier
movement. fine particles would be at the leading edge while larger
particles would have been closer to the glacier.
Assigned Readings

"Glaciers as Agents of Erosion" on pages 32-34 of your text book.
Assigned Activities

Complete Question # 12 on page 33 of your text book.
Test yourself
1. Where are continental glaciers found?
2. Where are alpine glaciers found?
3. Many land forms are created by continental glaciers. Which one is very
similar to a river delta?
4. Many land forms are created by continental glaciers. Which one is
created by a river running under the glacier?
5. Many land forms are created by continental glaciers. Which one is a
large boulder that looks out of place in its surroundings?
6. Many land forms are created by continental glaciers. Which one marks
the furthest extent of the glaciers movement?
7. Many land forms are created by continental glaciers. Which one is an
egg-shaped hill?
8. Which end of a drumlin indicates the direction of glacier motion?
Answers
1. Where are continental glaciers found? THE POLES OF EARTH
2. Where are alpine glaciers found? HIGH IN MOUNTAIN VALLEYS
3. Many land forms are created by continental glaciers. Which one is very
similar to a river delta? OUTWASH PLAIN
4. Many land forms are created by continental glaciers. Which one is
created by a river running under the glacier? ESKERS
5. Many land forms are created by continental glaciers. Which one is a
large boulder that looks out of place in its surroundings? ERRATICS
6. Many land forms are created by continental glaciers. Which one marks
the furthest extent of the glaciers movement? TERMINAL MORAINE
7. Many land forms are created by continental glaciers. Which one is an
egg-shaped hill? DRUMLIN
8. Which end of a drumlin indicates the direction of glacier motion?
POINTY
Alpine Glaciers
Alpine glaciers are like very slow moving rivers of ice flowing down high
mountain valleys. Like continental glaciers, alpine glaciers create land forms
by weathering and deposition. They typically erode the mountain beneath
them into a u-shaped valley with steep sides. Some alpine or valley glaciers
are 1000m thick and up to 160 km long, though most are only a few km in
length.
Features of Alpine Glaciation
Cirque
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a circular hollow cut into bedrock during glaciation;
side and back walls are steep but front wall opens downward.
Cirque Formation
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alpine glacier freezes onto mountain valley and as is proceeds it
plucks/gouges rock from the mountain top leaving the cirque shape.
Arête
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steep knife edged ridge between two cirques in a mountainous region.
Hanging Valley
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a high level tributary valley from which the ground falls sharply to the
level of the lower, main valley. The depth of the lower valley is due to
more severe glaciation.
Lateral Moraines
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land-form deposited at the side of a glacier.
Terminal Moraines
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deposits that mark the farthest extent of the alpine glacier the same
as with continental glaciers.
Fjords
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alpine Glaciers erode troughs and valleys in the mountain;
glacier valley reaches the coast;
glacier melts and sea water floods the valley;
fjords are very common in Norway and a quick search on web can find
you some amazing pictures.
Assigned Readings

"Alpine Glaciation" on pages 34-36 of your text book.
Assigned Activities

Do Question # 14 on page 36.
Test yourself
1. What alpine glaciation feature consists of a circular hollow cut into the
bedrock.
2. What alpine glaciation feature consists of a knife-like edge between
adjacent cirques?
3. What alpine glaciation feature consists of a valley that abruptly ends
as the main valley is at a much lower level?
4. What alpine glaciation feature consists of deposits along the side of the
glacier.
5. What alpine glaciation feature is formed when a valley glacier reaches
the ocean and eventually melts back.
6. What alpine glaciation feature is this.
7. What alpine glaciation feature is this.
8. What alpine glaciation feature is this.
Answers
1. What alpine glaciation feature consists of a circular hollow cut into the
bedrock. CIRQUE
2. What alpine glaciation feature consists of a knife-like edge between
adjacent cirques? ARETE
3. What alpine glaciation feature consists of a valley that abruptly ends
as the main valley is at a much lower level? HANGING VALLEY
4. What alpine glaciation feature consists of deposits along the side of the
glacier. LATERAL MORAINE
5. What alpine glaciation feature is formed when a valley glacier reaches
the ocean and eventually melts back. FJIORD
6. What alpine glaciation feature is this. CIRQUE
7. What alpine glaciation feature is this. ARETE
8. What alpine glaciation feature is this. HANGING VALLEY
Erosion and Ocean Waves/Currents
Erosion of Submerging Coastlines
Terms Related to Water/ Wave Erosion
Three Weathering Terms
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Hydraulic pressure: The pounding force of water/waves
Corrosion: Minerals such as calcium carbonate and limestone dissolve
in the water
Abrasion: rock and sand particles suspended in the water bump,
grind, scrape and gouge surfaces the water hits.
Longshore drift terms
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Headlands: the protrusions of land that extend the farthest out into
wave action.
Longshore drift: refers to the fact that dominant waves have enough
energy to carry silt/sand from headlands along the shore where it is
later deposited.
Wave Refraction: waves bending around headlands as they hit the
shallow water by shore
Spit: A ridge of sand running away from the coast, usually with a
curved seaward end. Spit grows in the prevailing direction of longshore
drift. Ends are curved by the action of waves in different directions.
Bay Bar: A ridge of mud sand or silt extending across a bay. Formed
when spits stretch across the mouth of the bay.
Bay Beach: An accumulation of sediment deposited by waves and
longshore drift along the shore of a bay.
Straightening of an Irregular Submerging Coastline
Irregular submerging coastlines have headlands that protrude out from the
shore line.
The erosion of the headland can deposit silt in the bay which forms a bay
beach as it tends to reduce the irregularity of the coastline. The headland is
reduced due to erosion and the bay is being filled by deposition.
Longshore drift results in some sand being deposited parallel to the shore but
connected to the headland. These silt deposits are known as spits.
Longshore drift and deposition can continue to the point that the spit closes
off the mouth of the bay. This extensive deposit is known as a bay bar. As
you can see it tremendously reduces the irregularity in the coastline.
Continued erosion and deposition can straighten a coastline over a long
period of time.
Assigned Readings
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
"Wave Movement and Direction" on pages 41-42;
"Effects of Wave erosion and Deposition" on pages 42-44.
Assigned Activities

Click on "Wave Erosion", open it, print it and complete it.
Test yourself
1. Water weather process where the pounding force of water/waves
causes physical weathering.
2. Water weather process where minerals such as calcium carbonate and
limestone dissolve in the water
3. Water weather process where rock and sand particles suspended in the
water bump, grind, scrape and gouge surfaces the water hits.
4. The protrusions of land that extend the farthest out into wave action of
the sea.
5. Refers to the fact that dominant waves have enough energy to carry
silt/sand from headlands along the shore where it is later deposited.
6. Waves bending around headlands as they hit the shallow water by
shore
7. A ridge of sand running away from the coast, usually with a curved
seaward end.
8. A ridge of mud sand or silt extending across a bay. Formed when spits
stretch across the mouth of the bay.
9. An accumulation of sediment deposited by waves and longshore drift
along the shore of a bay.
10.What is this structure?
11.What is this structure?
12.What structure is this?
Answers
1. Water weather process where the pounding force of water/waves
causes physical weathering. HYDRAULIC
2. Water weather process where minerals such as calcium carbonate and
limestone dissolve in the water. DISSOLVING
3. Water weather process where rock and sand particles suspended in the
water bump, grind, scrape and gouge surfaces the water hits.
ABRASSION
4. The protrusions of land that extend the farthest out into wave action of
the sea. HEADLAND
5. Refers to the fact that dominant waves have enough energy to carry
silt/sand from headlands along the shore where it is later deposited.
LONGSHORE DRIFT
6. Waves bending around headlands as they hit the shallow water by
shore. REFRACTION
7. A ridge of sand running away from the coast, usually with a curved
seaward end. SPIT
8. A ridge of mud sand or silt extending across a bay. Formed when spits
stretch across the mouth of the bay. BAY BAR
9. An accumulation of sediment deposited by waves and longshore drift
along the shore of a bay. BAY BEACH
10.What is this structure? SPIT
11.What is this structure? HEADLAND
12.What structure is this? BAY BAR
Curonian Spit Case Study
Assigned Readings

"CASE STUDY the Curonian Spit" on pages 45-46.
Assigned Activities

Complete Question #17 on page 46.
Erosion of Emerging Coastlines
The Evolution of Sea Stacks
Sea stacks are common in eastern Canada. Many have plant growth on top.
Sea stacks are columns of land standing in the ocean just off shore. They are
created over a long period of time after a series of other land structures have
eroded away. First sea caves are formed in a headland. Continued erosion
turns sea caves in to the second land feature, searches. sea arches are an
interesting sight too and have drawn many tourists to the northern Peninsula
of Newfoundland. Erosion and eventual collapse of the arch top leaves a sea
stack standing in the ocean. Figure 3.11 on pages 49-49 shows this
evolution from three different points of reference. You must look at this
figure it will help cement the concepts in your mind.
Sea Cave Formation: "a" in figure 3.11 on page 48
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waves strike the headland first;
waves refract around the headland and put hydraulic pressure on both
sides of the headland;
erosion of the weak portions create caves and blow holes in the sides
of the headland.
Sea Arch Formation : "b" in figure 3.11 on page 48
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eventually sea caves, on alternate sides of the headland get deeper
until they connect inside the headland forming a complete passage
way or tunnel or “arch” through the head land.
Sea Stack Formation: "c" in figure 3.11 on page 48
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continuous erosion, of sea arches, causes the collapse of the ground
over the arch;
this leaves a pillar or column or “STACK” of land standing alone where
the headland was.
Straightening of Emerging Coastlines
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emerging coastlines straighten in much the same fashion as
submerging coastlines;
erosion of headlands creates sea caves, sea arches and sea stacks
instead of bay beaches, spits and bay bars;
however the result is similar in that headlands are reduced in size
which straightens the coastline. Compare the headland length in figure
3.11 before and after erosion.
Assigned Readings

page 46
Test yourself
1. What name is given to columns of land standing in the ocean just off
shore.
2. Erosion of the weak portions in the sides of a headland create which
type of shore line feature?
3. When sea caves erode through a headland what shoreline feature is
created?
4. What wave phenomenon causes headlands to be eroded from both
sides?
5. Which type of water/wave erosion is mostly responsible for the erosion
that leads to the development of sea stacks.
6. After sea stack formation are headlands longer or shorter?
Answers
1. What name is given to columns of land standing in the ocean just off
shore. SEA STACK
2. Erosion of the weak portions in the sides of a headland create which
type of shore line feature? SEA CAVE
3. When sea caves erode through a headland what shoreline feature is
created? SEA ARCHES
4. What wave phenomenon causes headlands to be eroded from both
sides? WAVE REFRACTION
5. Which type of water/wave erosion is mostly responsible for the erosion
that leads to the development of sea stacks. HYDRAULIC AND
ABRASION
6. After sea stack formation are headlands longer or shorter? SHORTER
Landforms Affect Human Activity
Storm Surges in Bangladesh
Human adaptation to land forms and water forms
Humans have adapted to most conditions on earth. Look at the front cover of
your book and you can see how people of the orient have adapted to farming
on steep hillsides.
Look at many small fishing villages in Newfoundland and you will see how
people adapted to build houses up cliffs that overhang the ocean.
The stilt houses of Bangladesh show how humans have adapted to living in
delta regions.
A drive through most communities in Newfoundland will see you crossing a
number of bridges. Without the technology of bridge building access to many
places would be restricted to boat traffic. The Tunnel that was recently
completed under the English channel is a good example of overcoming
restrictions to access.
The Canadian railway finally overcame the restriction caused by the rocky
mountains.
Proposing Solutions to Problems
Some of the following suggestions will help in many case studies. Many times
you will be asked to put yourself in the position of government or other
influential groups. You will be asked what you would propose as solutions to
problems like the flooding in Bangladesh.
Researching to determine, what is the root of the problem is a good idea.
Funding a research facility to develop solutions to the problem.
Develop a government department to be responsible for the issue.
Study other world locations that have solved similar problems. It is not
necessary to reinvent the wheel.
It is always important to keep financial restrictions in mind, many countries
like Bangladesh have limited resources. Searching for funding from world
bank and international aid might be a good idea.
Assigned Readings

"Storm surges in Bangladesh" on p. 50-51 in your text book
Assigned Activities
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Can you think of a land or water form that humans have adapted to or
overcome in your community or region? If so share it with the class.
Can you think of a land form or water form that has restricted human
access in your community or region? If so share it with the class.
Click on Hazard analysis model open it and print it to use as you
complete question #22a p. 51.
If you were a member of Government in Bangladesh what solutions
would you propose to prevent further storm surge tragedies.
Economic Proposal
You will be expected to write an economic proposal for a given land form or
water form. You could be asked to write a proposal for a river with many
large water falls or with small rapids; you could be asked to write a proposal
for a mountain near the coast.
The point here is that you bring your knowledge of geography to the answer.
You must propose what economic value there is in the area. Consider the
following when you do a proposal.
1. The economic activity must fit the terrain. For example a hydroelectric
generating station on a slow meandering old river might not be a good
idea whereas boat tours might be.
2. How would the environment be impacted? Obviously you would need
an environmental impact study and a means of reducing the impact on
nature.
3. Is the area accessible to people or machinery? You must be able to
access it to make money.
4. How might building and erosion forces impact your proposal in the
short term and long term?
5. What types of potential problems accompany the land or water form.
For example flooding accompanies old meandering rivers.
Assigned activities
Using the search engine of your choice find a picture of any land form or
water form and write an economic proposal for use of it. Be sure to include
at least the 5 points mentioned in the lesson.
Type the proposal in word and include the photo of the land or water form.
Erosion and Wind
Wind Erosion
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Deflation: Process where soil particles are removed leaving the land
slightly lowered or hollowed. See figure 3.2 on page 39.
Abrasion: Wind-borne particles blown against any surface acts as a
sand blaster
Loess Originally referred to loose, fine grained soil in the Rhine
river valley. Now it refers to any unconsolidated, unstriated soil
composed of fine/clay sized soil particles. It is Very fertile
agricultural soil. It Can blow long distances and collect in
specific regions.
Hamadas: rocky deserts. Rocky portion of desert where wind
removes all sand and small particles. Jagged rocks and flat pans of
bedrock are common. See Figure 3.3 on page 40.
o Hamadas formation:
o Wind blows away all loose soil and particles
o Landscape appears jagged and bare with exposed bedrock
o Any loose soil is compacted coarse stone
Erg: Sandy deserts. Sandy portion of desert where wind blown sand is
deposited. Sand dunes, ridges and mounds are common
Barchan: Crescent shaped sand dunes. The horns or arms extend in
the direction of the wind. See Figure 3.4 on page 41.
o
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Assigned Readings


"Wind Erosion" pages 38-39 in your text book;
"Wind Deposition" pages 39-40 in your text book.
Test yourself
1. Process where soil particles are removed leaving the land slightly
lowered or hollowed?
2. Unconsolidated, unstriated soil composed of fine/clay sized soil
particles. It can blow in the wind for long distances?
3. Wind-borne particles blown against any surface acts as a sand blaster
4. Rocky deserts?
5. Sandy deserts. Sandy desert?
6. Crescent shaped sand dunes?
Answers
1. Process where soil particles are removed leaving the land slightly
lowered or hollowed. DEFLATION
2. Unconsolidated, unstriated soil composed of fine/clay sized soil
particles. It can blow in the wind for long distances. LOESS
3. Wind-borne particles blown against any surface acts as a sand blaster.
ABRASION
4. Rocky deserts. HAMADAS
5. Sandy deserts. ERG
6. Crescent shaped sand dunes. BARCHANS