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Unit 5
Weathering
Erosion
Deposition
Landscapes
A. Weathering
The breakdown of rock due to physical or
Weathering:_____________________________________
chemical changes.
______________________
2 types of weathering:
Changes in the size and/or
• Physical Weathering:__________________________
shape of the rock, without changing it’s chemical
________________________________________
composition.
_________________
Frost Action, plant/animal action, abrasion
--Ex: _____________________________________
and exfoliation.
_________________
(Hitting, scratching, cracking)
• Chemical Weathering: __________________________
Changes the mineral
composition of the rock, making it a new substance.
_________________________________________
Acid rain and rusting.
--Ex: _____________________________________
B. Physical Weathering
Examples:
•Water seeps into small cracks in rocks.
• Frost Action-_______________________
___________________________________
•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
Ex:_________________________________
B. Physical Weathering
Examples:
• Plant and Animal Action:
•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.
Ex:_________________________________
• A strangler fig tree taking over an ancient temple.
When rock surfaces rub together or collide.
• Abrasion: __________________________
Ex:________________________________
1-WIND blows sand into other rocks.
STREAM WATER carries rocks on the bottom and
2-__________________________________
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.
___________________________________
WAVES constantly attack rocks and sediment
• Ex: 4-_____________________________
along shorelines.
___________________________________
B. Physical Weathering
Examples:
• Exfoliation:
•Rocks
formed deep in the Earth are made under high
________________________________________________________
pressure.
_______________
•When
the pressure is released the rocks expand & crack.
________________________________________________________
C. Chemical Weathering
Examples
• 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 Rate
more
– Weathering occurs on the surface. The ____
faster
surface area exposed, the ________
the rate
of weathering.
Surface exposed
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- ________________
some minerals
are more resistant than others.
___________________________________
Quartz
-Ex: ________
is resistant to physical
and chemical weathering.
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…
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
The mixture of weathered rock,
• Soil-______________________________
microorganisms, and organic remains
__________________________________
that usually covers bedrock.
___________________________________
Bedrock is the rock that is on the bottom of all the loose
soil.
-Soil forms layers that have different characteristics.
Horizons
These layers are called ______________.
F. Erosion
Rocks that have been broken into
• Sediments:_________________________
fragments of any size.
___________________________
The transportation of sediments,
• Erosion:___________________________
mostly by water, wind, or glaciers
______________________
• What is the main force that drives
erosion?
force of gravity drives most
• The_______________
forms of erosion.
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?
Gravity only
1. Erosion by _____________________
The downhill movement of
-Mass Movement: __________________________________
sediment without being carried by wind, water, or
__________________________________________________
_____
ice.
Slow creep, slumping, landslides
Ex: _____________________________________________.
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 __________.
Wind
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.
Ice
3. Erosion by _____________________.
Glaciers
_______________:
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
U-Shaped Valley
shape is called a ____________________.
Water
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.
V-Shaped Valleys
These are called______________________
.
G. Stream Erosion
The amount of sediment and the size of sediment
carried by a stream are dependent on the
Stream’s velocity
_________________,
or stream speed.
A stream’s speed or velocity is dependent on 2
variables.
Stream gradient
_________________
-how steep the stream is.
Stream discharge
_________________
-the amount of water flowing in
the stream.
The _______
steeper the gradient,
the ___________
the
faster
stream’s velocity.
greater
The _________
the
faster
discharge, the __________
the stream’s velocity.
So, the faster a stream is moving the ______________
more amount of
sediment it can carry, and the ___________
sediment
larger
size it can carry.
Meandering (Curving) River/Stream
Erosion
happens
on the
outside of
turns.
Deposition
happens on
the inside
of turns.
outside
Erosion occurs on the _______________
of the curve
because the stream velocity is _____________.
faster
inside
Deposition occurs on the _____________
of the curve
because the stream velocity is _____________.
slower
Evolution of a stream
Young
Intermediate
Old
H. Deposition
When an agent of erosion deposits, or
Deposition:__________________________________
stops transporting, sediments.
___________________________________
1. Factors that Affect Deposition:
Particle SizeSmaller particles settle slower, and larger
__________________________________________
particles settle faster.
___________________________________________.
fast
slow
Particle ShapeFlat or angular particles settle slower, and
________________________________________
rounded particles settle faster.
____________________________________________.
fast
slow
Particle Density_______________________________________
Particles with a lower density settle slower, and
particles with a higher density settle faster
_______________________________________.
fast
Galena
High Density
slow
Sulfur
Low 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
Time
Settling
Rate
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
decreases
densest particles are deposited_________,
first
near the
shoreline. The smallest, flattest, least dense particles
are carried further from the shoreline, and
last
settle_______.
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
bottom
least dense particles settle at the ______of
the same
top
layer.
• 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 4
Trial 3
Trial 2
Trial 1
You can identify which agent of erosion transported each sediment by looking at
a few characteristics:
Running Water – sediments that have been transported through
rounded
smooth
running water appear _________and
_________and
are deposited in
sorted piles.
________
Glaciers – sediments that have been transported by glaciers appear
scratched grooved, and are deposited in completely
___________,
__________
unsorted piles, because they were dropped during melting.
Also, ___________
boulders can only be transported by glaciers.
Wind - sediments that have been transported by wind are appear
pited
frosted
__________
(random holes) and ___________
(glazed look) and
are deposited in __________
piles. Only very small particles can
sorted
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___________.
unsorted
4. Glacial Deposits