Unit 5

Weathering

Erosion

Deposition

Landscapes

Weathering:___________________________________________________________

2 types of weathering:• Physical Weathering:__________________________

________________________________________

_________________

--Ex: _____________________________________

_________________

(Hitting, scratching, cracking)• Chemical Weathering: __________________________

_________________________________________

--Ex: _____________________________________

A. WeatheringThe breakdown of rock due to physical or chemical changes.

Changes in the size and/or shape of the rock, without changing it’s chemical composition.

Frost Action, plant/animal action, abrasion and exfoliation.

Changes the mineral composition of the rock, making it a new substance.

Acid rain and rusting.

• Frost Action-_______________________

___________________________________

___________________________________

Ex:_________________________________

B. Physical WeatheringExamples:

•Water seeps into small cracks in rocks.

•When the water freezes it expands creating great pressure.

•The crack widens and allows water to seep deeper into the rock.

Frost Wedging and potholes

B. Physical WeatheringExamples:

• Plant and Animal Action:

__________________________________

___________________________________

___________________________________

Ex:_________________________________

•Tiny root hairs seek out small cracks and pits in rock.

•Once the root hairs find a place they grow and expand.

•The expansion causes great pressure and cracks the rock.

•Trees in rock/cement, animals digging/scratching on rocks.

• A strangler fig tree taking over an ancient temple.

• Abrasion: __________________________

Ex:________________________________

2-__________________________________

When rock surfaces rub together or collide.

1-WIND blows sand into other rocks.

STREAM WATER carries rocks on the bottom and smashes the rocks into each other.

• Sculpted by wind, somewhere in Utah.

• Double arches, Arches National Park, UT

• Ex 3- _____________________________

___________________________________Moving ice (glaciers) drags, scrapes, and breaks apart rocks.

• Ex: 4-_____________________________

___________________________________

WAVES constantly attack rocks and sediment along shorelines.

B. Physical WeatheringExamples:

• Exfoliation: ________________________________________________________

_______________

________________________________________________________

•Rocks formed deep in the Earth are made under high pressure.•When the pressure is released the rocks expand & crack.

C. Chemical WeatheringExamples

• Oxidation• Oxygen in the atmosphere chemically reacts with minerals.• ex.: rusting of a nail•

Water (hydrolysis)• Minerals are dissolved in water.• ex.: Halite, calcite• Acid• Carbonic acid:

– C02 dissolves in rain water forming a weak acid (seltzer). 

– Acid Rain: Sulfur Dioxide in the atmosphere dissolves in rain water forming a strong acid (sulfuric acid).

_______________________________________________________________________________________

_________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

Oxidation (Rust)

Water (hydrolysis)

Acid Rain

D. Factors that influence the rate of weathering.

• Surface area.– Weathering occurs on the surface. The ____

surface area exposed, the ________ the rate of weathering.

Surface exposed

Wea

ther

ing

Rat

e

more

faster

A full, solid block has the least surface area.

The interior is safe from exposure.

A smashed piece has greatest surface area exposed. The interior can now be attacked.

• Mineral composition- ________________

___________________________________

-Ex: ________ is resistant to physical

and chemical weathering.

some minerals are more resistant than others.

Quartz

Where is the rock more resistant to weathering?

Where is the rock least resistant to weathering?

You might also see it like this…You might also see it like this…

You might also see it like this…You might also see it like this…

D. Factors that influence the rate of weathering.

• Climate Conditions– ____________________________________

____________________________________

– ________________________________________________________________________

– ________________________________________________________________________

Cold and/or arid(dry) climates favor

physical weathering. (Mid-northern U.S.)

Warm and humid(wet) climates favor

chemical weathering. (Southeastern U.S.)

Frost action works best in a climate where

the temperature fluctuates a lot. (New York)

E. The Product of Weathering

• Soil-______________________________

__________________________________

___________________________________

Bedrock is the rock that is on the bottom of all the loose soil.

-Soil forms layers that have different characteristics.

These layers are called ______________.

The mixture of weathered rock,microorganisms, and organic remainsthat usually covers bedrock.

Horizons

F. Erosion• Sediments:_________________________

___________________________

• Erosion:_________________________________________________

• What is the main force that drives erosion?

• The_______________ drives most forms of erosion.

Rocks that have been broken into fragments of any size.

The transportation of sediments,mostly by water, wind, or glaciers

force of gravity

For example, weathering weakens the rock on a cliff. The rock is pulled down by gravity, causing it to fall to the bottom of the cliff.  Gravity is also the force pulling water down a stream or pulling sediment that is blowing around in the air back down to the ground.

What are the different types of erosion? 1. Erosion by _____________________ -Mass Movement: _________________________________________________________________________________________ Ex: _____________________________________________.

Gravity only

The downhill movement of sediment without being carried by wind, water, or ice.

Slow creep, slumping, landslides

This is a diagram of creep. The hillside slowly slips over many

years from temperature or water.

In this picture the land has slumped

into the road below.

This is a picture of a landslide. A type of mass

wasting.

This is a picture of an avalanche. It is similar to a landslide with ice and snow

instead of rock.

2. Erosion by __________.

This type of erosion occurs mainly in desert areas and beaches, where there is little plant life to hold the soil or sediments in place.

Wind

3. Erosion by _____________________. _______________: Are large masses of slowly flowing ice. As a glacier moves, it carries, pushes, and drags loose rock material. Glaciers carve out a certain shape in the landscape. This shape is called a ____________________.

Ice

Glaciers

U-Shaped Valley

4. Erosion by: _________. ***Running water is the main agent of erosion in moist areas*** *Every year, streams are responsible for moving millions of tons of sediments to oceans and lakes. Streams carve out a certain shape in the landscape. These are called______________________ .V-Shaped Valleys

Water

G. Stream Erosion The amount of sediment and the size of sediment carried by a stream are dependent on the _________________, or stream speed.

A stream’s speed or velocity is dependent on 2 variables. _________________ -how steep the stream is. _________________ -the amount of water flowing in the stream.

Stream’s velocity

Stream gradient

Stream discharge

The _______ the gradient, the ___________ the stream’s velocity.

 The _________ the discharge, the __________ the stream’s velocity.

steeperfaster

greater

faster

So, the faster a stream is moving the ______________ sediment it can carry, and the ___________ sediment size it can carry.

largermore amount of

Meandering (Curving) River/Stream

Erosion happens on the outside of turns.

Deposition happens on the inside of turns.

Erosion occurs on the _______________ of the curve because the stream velocity is _____________.Deposition occurs on the _____________ of the curve because the stream velocity is _____________.

inside

outside

slower

faster

Evolution of a stream

Old

Young

Intermediate

H. Deposition

Deposition:_____________________________________________________________________

When an agent of erosion deposits, or stops transporting, sediments.

1. Factors that Affect Deposition: Particle Size-_____________________________________________________________________________________.

Smaller particles settle slower, and larger particles settle faster.

fast slow

Flat or angular particles settle slower, and rounded particles settle faster.

Particle Shape-____________________________________________________________________________________.

fast slow

Particle Density-______________________________________________________________________________.

Particles with a lower density settle slower, and particles with a higher density settle faster

fast slow

GalenaHigh Density

SulfurLow Density

2. Settling Rate and Settling Time- This is an inverse relationship. Sediments that settle at a faster rate require less settling time. Therefore, as the rate of settling increases, the settling time decreases.

Settling Rate

Settling Time

3. Deposition of Mixed Sediments

Horizontal Sorting-When a stream/river enters a larger body of water, the velocity of the stream____________. The largest, roundest, and densest particles are deposited_________, near the shoreline. The smallest, flattest, least dense particles are carried further from the shoreline, and settle_______.

decreasesfirst

last

Vertical Sorting- When particles settle in calm water, the roundest, largest, and densest particles quickly settle at the _______of a layer, while the flattest, smallest, and least dense particles settle at the ______of the same layer.

bottomtop

• The degree of sorting is related to the depth of the water the particles are traveling through.

• The deeper the water the greater the sorting.

• This is also called GRADED BEDDING Trial 1

Trial 2

Trial 3

Trial 4

You can identify which agent of erosion transported each sediment by looking at

a few characteristics:Running Water – sediments that have been transported through running water appear _________and _________and are deposited in ________ piles.

Glaciers – sediments that have been transported by glaciers appear ___________, grooved, and are deposited in completely __________ piles, because they were dropped during melting. Also, ___________ can only be transported by glaciers.

Wind - sediments that have been transported by wind are appear __________ (random holes) and ___________ (glazed look) and are deposited in __________ piles. Only very small particles can be transported by wind.

Gravity – sediments that are transported by gravity are found in piles at the bottom of cliffs or steep slopes. They appear angular and___________.

rounded smoothsorted

sorted

frostedpited

unsorted

scratched

boulders

unsorted

4. Glacial Deposits