Lessons 20-22 Outline - Clark-Shawnee Local School District

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Transcript of Lessons 20-22 Outline - Clark-Shawnee Local School District

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?