lessons 20-22 outline - clark-shawnee local school district
TRANSCRIPT
Lessons 20-22 Outline
Lesson 20: Weathering (Slides 3-53)
Lesson 21: Erosion (Slides 54-74)
Lesson 22: Deposition (Slides 75-99)
Slides 100-114: Optional Slides from
original PowerPoint
Lessons 20-22 Overview
Lessons 20-22 deal with how the Earth is
shaped by Weathering, Erosion and
Desposition.
We have learned about large scale
movements of the Earth's crust with Plate
Tectonics and Continental Drift.
These lessons are about smaller scale
processes that shape the Earth's crust
Weathering
What is Weathering?
Weathering is the breakdown of
rocks into smaller pieces, called
sediments
◦ It is a slow, continuous process
◦ Effects aren’t easily observed
There are two general types of
weathering:
1. Physical (Mechanical)
2. Chemical
Physical or Mechanical Weathering
The breakdown of rocks into smaller
pieces WITHOUT a change in chemical
composition
Forms of Physical Weathering:
◦Water
◦Wind
◦ Frost Wedging
◦ Plant/Root Wedging
◦ Abrasion
◦ Exfoliation
Water Weathering
Water can weather rocks by its
movement
• Rain
• Waves
• Rivers
• Runoff
Wind Weathering Breakdown of
rocks by moving air
carrying sediments
especially sand
Wind Weathering
Frost Wedging – freezing of
water in cracks of rock
Frost Wedging
Frost Wedging Water seeps into small cracks, freezes and
expands by 10%, exerting great pressure on
the rock making the cracks bigger over time
◦ Cracks in sidewalks
◦ Potholes in roads
Plant/Root Wedging Plat roots help to widen cracks made
by other means
Plant roots growing in the soil can
loosen rock, which makes cracks bigger
over time
Plant/Root Wedging
Changes in Temperature
• Occurs where rock surfaces are exposed to daily
heating and cooling
• Rock minerals, because they have different
combinations of elements, have different thermal
expansion and contraction rates
• This causes internal stresses and eventually the
rock crumbles
• Very slow process
• Responsible for most of the world’s sandy deserts
Sun split rock
Exfoliation
The “peeling” away of a rock layer
caused by repeated heating and
cooling of rock
Release of Pressure
• Also called Unloading
• When surface layers are removed newly
exposed rock often can expand due to the
release of overlying weight and the rock
cracks
• Can create exfoliation domes where large
sheets of rock crack and peel away, like an
onion
As erosion removes rock
material from the surface
of the land, the underlying
rocks are under less
pressure.
As the pressure is lowered
on them, the rocks expand
upwards, creating fractures.
Slabs of rock then 'peel off'
along the fractures, creating
domical hills.
Famous 'Half Dome
Mountain' is an example of
an Exfoliation Dome.
Abrasion
Rough edges of particles scrape off
parts of rocks
Think of abrasion like the dice you
shake in Yahtzee…
https://www.youtube.com/watch?v=mB1s
Ycj0mVc
Watch this video
Chemical Weathering
The breakdown of rocks into smaller
pieces and CHANGES the rock’s
chemical composition, which results
in a different rock from the original
Forms of chemical weathering:
◦ Effects of Acids
◦Oxidation
Effects of Acid
Water can dissolve away
many Earth materials,
including certain rocks
Acid rain can also break
down rock
◦ Burning fossil fuels releases
gases in the atmosphere,
which can cause rain to
become more acidic
Rain made up of
water (H2O)
and carbon
dioxide (CO2)
form a weak
carbonic acid
(H2CO3) to
weather surface
structures.
Effects of Acid
Effects of Acid
Calcite vs. Hydrochloric Acid
Watch this video
Effects of Acid
• The acid reacts on basic rocks such as
limestone
• Certain minerals like calcite are dissolved
and carried away by erosion
• Eventually the limestone is completely
removed leaving caverns, sink holes and
even underground rivers
Karst Topography
Where limestone is widespread in a region, a
distinctive type of topography called Karst is
produced
Karst
Topography
Karst
Topography
Karst Topography Worldwide
Karst
Topography
What Causes
Sinkholes? https://www.youtube.com/wat
ch?v=9h2j-X2mppU
Sinkhole Forminghttps://www.youtube.com/wat
ch?v=2jMOSMVaIfs
Compilation of
Sinkholes
https://www.youtube.com/wat
ch?v=dHdqu-75RVs
Watch these videos
OxidationOxygen reacts with elements that
make up the rock
Iron in a rock reacts with oxygen,
causing a color change
(Rust is an Oxidation reaction)
What Effects Weathering Rate?
Rock Composition
Surface Area
Particle Size
Climate
Time
Weathering
Rate: Rock
Composition
Brittle
rocks will
weather
faster than
stronger
ones
Weathering Rate: Surface Area
Exposing more of the rock will speed
up weathering
Weathering Rate: Particle Size
Larger particles weather slower and
smaller particles weather at a faster
rate
Weathering Rate: Climate Warm, moist climates have the most
weathering.
Heat and water can greatly increase
the speed of chemical weathering.
Weathering Rate: Time
Obviously the longer a rock is
exposed to its surroundings the
more it will be effected by
weathering processes
THIS IS THE END OF
LESSON 20
ANSWER THE QUESTIONS
ON THE NEXT SLIDE AND
SHARE THEM WITH ME
Lesson 20 Questions
1. What are the TWO types of weathering?
2. Describe the difference between the two
types of weathering.
3. Name at least THREE types of Physical
Weathering.
4. Describe and explain in detail an example of
physical weathering that you have experienced
in your life (or at least heard about).
Erosion
What is Erosion?
The process where weathered rock and soil are transported or moved from one location to another
There are 6 main agents of erosion:1. Gravity
2. Wind
3. Running Water
4. Glaciers
5. Waves
6. Humans
Gravity
Pulls on rocks and soil down slopes
◦ Landslides
◦Mudflows
◦ Avalanches
Wind
Tiny particles, often filled with holes
are transported by wind
Major agent of erosion in hot, dry
climates or places with little
vegetation
◦ In the desert, wind can erode soil enough
that water is present, which allows
shrubs/grasses to grow → Oasis
Running Water
Sediments are transported in running
water at the bottom of the river, flowing
in the middle of the river, or as dissolved
particles
Three factors effect the erosion rates in
running water:
1. Slope of the land
2. Volume of the running water
3. Position within the running water
Running Water – Slope
When slope increases…
◦Water velocity increases
◦ Particle size that can be carried increases
So erosion increases
Running Water –Volume
When volume increases…
◦Water velocity increases
◦ Particle size that can be carried increases
So erosion increases
Running Water – Position
Particles near the outside of turns
move faster -- erosion increases.
Particles near the inside of turns move
slower -- more particles are deposited.
Particles suspended in the water will
move faster than particles at the
riverbed.
Running Water – Position
Running Water – Position
Why Do Rivers Curve?https://www.youtube.com/wa
tch?v=8a3r-cG8Wic
Watch this video
Glaciers
Produce large-scale dramatic effects
Can carry HUGE rocks and piles of
debris over great distances
Glaciers can groove or scar the
Earth when passing through
Ohio’s landscape has been changed
dramatically by glaciers.
Glacial grooves on Kelley’s Island
in Lake Erie
Glaciers
Inside a
Glacier https://www.youtub
e.com/watch?v=Gbf
u2-Z_iDI
Watch this video
Waves
Small sediments near coastal areas
are easily swept away by ocean
waves, storms, or wind.
Humans Humans change
the landscape in many ways, which result in a faster rate of erosion.◦ Deforestation
◦Mining
◦ Construction
◦ Improper farming
THIS IS THE END OF
LESSON 21
ANSWER THE QUESTIONS
ON THE NEXT SLIDE AND
SHARE THEM WITH ME
Lesson 21 Questions
1. Name 3 types of Erosion
2. Name one way that water erosion's affect
on the land can be incresed. There are three
possible answers.
3. Do you live in the part of Ohio that is
glaciated (run over by a glacier in the past) or
unglaciated (more hilly areas)?
4. What DO YOU THINK is the most
powerful type of erosion? Why do you think
this?
Deposition
What is Deposition?
The process where eroded material
slows down, stops, and settles in a
new area
This material can often form new
landforms
There are three factors that affect the
rate of deposition:
1. Sediment size
2. Sediment shape
3. Sediment density
Deposition Rate: Sediment Size
Larger sediments are typically
deposited first because they cannot
be carried as far by the agent of
erosion
Deposition Rate: Sediment Shape
Round/spherical particles settle at a
faster rate than flat particles because flat
particles tend to be swept up by
currents
Deposition Rate: Sediment Density
Particles with higher density will
settle at a faster rate than particles
with lower density
Iron Styrofoam
Deposition Formations
Deposition formations come in all
shapes and sizes and are different based
on which type of erosion caused the
particles to move
◦ Gravity
◦Wind
◦ Running Water
◦ Glaciers
◦Waves
◦ Humans
Gravity Deposition
Scree – a collection of small rock
debris built up on the steep sides of
mountains
Talus – a collection of large rock
debris built on the steep sides of
mountains
Gravity Deposition
Scree
Talus
Wind Deposition
Erg – an area that has collected large
amounts of wind blown sand due to
slowing wind speeds
Dune – a large accumulation of sand
in one area, which eventually creates
a “sand hill”
Wind Deposition
Erg
Dune
Running Water Deposition
Delta – a landform that is created by the
collection of sediments where a river
empties into a larger body of water
Levee – naturally forming barrier on the
sides of a river caused by the deposition
of sediment during a flood
Running Water Deposition
Levee
River Delta
Running Water Deposition
Floodplain – area surrounding a river or
stream that is covered with sediment
from the river due to flooding
Glacier Deposition
Esker – a long unified ridge formed
within ice-walled tunnels or flowing
under glaciers
Kame – a hill or mound that formed
from sediment within a melting
glacier
Glacier Deposition
Kame
Glacier Deposition
Moraine – material left behind by a
moving glacier, usually consisting of
rock and soil
Kettle – when part of a glacier
breaks off and lodges into the
sediment, melts, and results in a
shallow body of water
Glacial Deposition
Moraine
Kettle
Wave Deposition
Beach – sand deposited in an area
where waves begin to slow and
retreat back into the ocean
Barrier Spit – an extension of the
land near the coast caused by the
build up of sand/sediments in a given
area
Wave Deposition
Beach
Barrier Spit
Human Deposition
Acid deposition – the addition of
acidic chemicals to the atmosphere,
water, or land by humans
Dams – man made barrier to hold
back water usually in order to
generate power
Human Deposition
Acid
Deposition
Dam
Weathering, Erosion, and Deposition
Now that we have covered all of these topics
think about how they are all connected…
Weathering breaks down the rock into
smaller pieces, or sediments
Erosion takes those sediments and moves
them to a new place
Deposition takes the sediments when
slowed/stopped and settles them to
eventually create a new landform
THIS IS THE END OF
LESSON 22
ANSWER THE QUESTIONS
ON THE NEXT SLIDE AND
SHARE THEM WITH ME
Lesson 22 Questions
1. How does deposition weathering and
erosion relate to each other? In other words
how does each process work together to
shape the Earth's crust?
2. Springfield is hilly compared to Northwest
Ohio where I am from. Why do you think
Springfield is hillier than Northwest Ohio but
not as hilly/mountanous as Southeastern Ohio?
This requires more than just one word and
more than just one sentence. Revisit the
slides from lesson 21.
The rest of this
PowerPoint
is optional
Section 4: Case Study
Essential Questions:
1. What type of the landform is discussed?
2. How did the following Earth processes
create/change the landform?
Weathering
Erosion
Deposition
Case Study: Wulingyuan
Wulingyuan is located in the Hunan
Province in China
It is characterized by approximately
3,100 quartzite-sandstone pillars
These pillars were created over a long
period of time and give scientists
valuable information about the
geological history of the area.
Case Study: Wulingyuan
The area of Wulingyuan was at one time
all at the same elevation, near the peaks
of the pillars.
The giant pillars began to take their
shape as water seeped into cracks in the
Earth and eventually created caves.
The caves collapsed causing the area
surrounding the pillars to fall, leaving
behind the pillars as we see them today.
Case Study: Wulingyuan
Case Study: Wulingyuan
The pillars stayed standing through the
water erosion because of their
composition.
Quartzite is a harder rock and more
resistant to water erosion.
In addition to water erosion, gravity
erosion and root wedging have helped
the pillars assume their current shape.
Case Study: Wulingyuan
Section 4: Case Study
Essential Questions:
1. What type of the landform is discussed?
2. How did the following Earth processes
create/change the landform?
Weathering
Erosion
Deposition
Section 1: Weathering
Essential Questions:
1. What is weathering?
2. Compare and contrast physical and
chemical weathering
3. Categorize the specific forms of
weathering we discussed.
4. What factors effect the rate of
weathering?
Section 1: Weathering
Essential Questions:
1. What is weathering?
2. Compare and contrast physical and
chemical weathering.
3. Categorize the specific forms of
weathering we discussed.
4. What factors effect the rate of
weathering?
Freeze/Thaw Animation
http://occ.crescentschool.org/geography/p
hysical/Flash/WearandTear/Mechanical_W
eathering.swf
Section 2: Erosion
Essential Questions:
1. What is erosion?
2. Describe the different agents of
erosion?
3. What factors affect the rate of erosion
in running water?
Section 2: Erosion
Essential Questions:
1. What is erosion?
2. Describe the different agents of
erosion?
3. What factors affect the rate of erosion
in running water?
Section 3: Deposition
Essential Questions:
1. What is deposition?
2. What factors affect the rate of
deposition?
3. What formations can result from
deposition?
4. How are weathering, erosion, and
deposition connected?
Section 3: Deposition
Essential Questions:
1. What is deposition?
2. What factors affect the rate of
deposition?
3. What formations can result from
deposition?
4. How are weathering, erosion, and
deposition connected?