1. Earth Science Review for test
Erosion
I. Erosion
A. transportation of rock, soil, and minerals particles from one place to
another.
• Erosion is done by water, wind or ice.
• The key ingredient behind all the agents of erosion is
GRAVITY.
• What is a transportation system?
– This includes all agents involved in erosion and
weathering
• Transportation agent
• Energy
• And the material moved
II. What proofs do we have that sediments move?
A.There are two main proofs
• Transported Sediments
– The very fact that the sediments are found in places
away from it’s origin
– Beaches along the coast get its sand (transported
sediment) from mountains in the inland.
– They were brought from rivers and streams into the
ocean.
• Residual Sediments
– Is the material that remains at the location of the
weathering
– and transported sediments is the erosion product that
is moved from the source.
– In New York State there are more
transported sediments than
Residual
III. Properties of transported materials

2. Earth Science Review for test
• We just learned that there common transporting agents
– Ice
– Water
– Wind
• Transported material often contain
characteristics that tell us what
eroding force and form of
transportation was done
– Water tends to smooth and round out sediments
– Wind tend to be often pitted or “frosted” as a result of abrasions
during travel
– The longer the wind or water action occurs the smoother and
rounder the sediments become
– Ice ( glacier) sediments usually have scratches
on the surface due to being pushed and scraped
by ice
– Gravity alone the sediments are sharp edged
and angular.
• Can see this at the base of the mountains
V. There are many things that affect transportation
– Gravity
– Wind
– Ice
– Humans
– Gravity
– Most of the transportation systems are caused by
gravity
– Gravity as discussed before can work alone
– Loose pieces of rocks on the side of a slope
– Gravity also works with the other systems

3. Earth Science Review for test
– Especially water in a stream
– Water
– Running water is (stream) is the predominant form of erosion on
Earth
– As stream cut into the underlying bedrock they cut V shaped
valleys
– There are a number of factors that affect the way running water of a
stream transports sediments
VI. Water, velocity & Sediments
• In a stream channel the average speed of
running water increases with the increase of
Discharge
– Discharge – is the volume (amount) of
water in a given location during a
specific amount of time
– The relationship between the velocity and discharge is
interdependent.
• In the spring streams usually move faster because of the
melted ice and snow
– The velocity ( speed) of the water in a stream is directly effected to
the slope of the stream
– As the slope increases the velocity
increases
– The fastest water in a stream with a straight
course ( path) is in the center just below the
place where there is the least friction
– Meandering Stream is a curved stream
• The highest velocity is on the outside of the curve
• Therefore erosion is greater on the
outside of the curve (meander)

4. Earth Science Review for test
• Deposition ( deposit) takes place on the inside of the
meander (curve)
• Between the meanders is called a change over .
– Boundaries between erosion and deposition (leaving the
sediments) occur in many places of the length of the stream
• These boundaries usually occur
• Midstream in meanders and where changes of
velocity occurs
• Near the mouth of the stream
• Where nether erosion or deposition occur
– Friction
• The greater the amount of friction (force
found in between 2 surfaces that offers
resistance to motion) the slower the water is
• The more efficient channel is one that is
smooth and has a semicircular shape.
One more key point
- As the velocity of a stream
increases the size of the particles that can be
moved increases in two ways
• Solution – dissolved in the water
• Suspension – (sand, clay silt) by bouncing or
dragging these materials along the stream’s bed
( ground made out of pebbles, cobblers, and boulders
Words you have to know from these notes
Friction
Discharge
Solution
Suspension

5. Earth Science Review for test
Channel
Velocity
Meandering stream
You should be able to answer questions in your book. If you can not answer some of
them call me or email me over the weekend
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