Name: _______________________
Topic 9: Weathering & Erosion (pp.157 – 170)
Weathering (p.157 – p.158)
The chemical and physical breakdown of rocks at or near Earth’s surface is called WEATHERING.
When does weathering occur? WHEN ROCKS ARE EXPOSED TO AIR, WATER, & THE
ACTIONS OF LIVING THINGS
What are the two types of weathering? CHEMICAL and PHYSICAL.
Define Chemical weathering: BREAKDOWN OF ROCK THROUGH A CHANGE IN MINERAL
OR CHEMICAL COMPOSITION
Exposing iron to oxygen causes rust (an oxidation reaction).
How does water chemically breakdown minerals? WATER DISSOLVES ROCK MATERIAL
Explain what happens when groundwater becomes acidic. LIMESTONE & MARBLE ARE
DISSOLVED.
Define physical weathering: BREAKDOWN OF ROCK INTO SMALLER PIECES WITHOUT
CHEMICAL CHANGE
What is frost action? WATER SEEPS INTO A CRACK IN A ROCK, THE WATER EXPANDS
WHEN IT FREEZES, ENLARGING THE CRACK.
When rock particles grind against one another it is called ABRASION . After a rock has been
abraded by running water it has a particular shape. What is the shape of a rock that has been
abraded by running water, such as a river? ROUND & SMOOTH
Factors Affecting the Rate and Type of Weathering (p.158 – p.159)
Both the rate and type of weathering are dependent on the exposure of rocks to AIR, WATER, and
ACTIONS OF LIVING THINGS.
Figure 9-2 is important!
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Name: _______________________
Topic 9: Weathering & Erosion (pp.157 – 170)
Why do some rocks, like limestone and marble, weather rapidly?
THEY DISSOLVE IN ACID
Rate of weathering  fast
When the rock particles are smaller, the total surface area per unit volume exposed to weathering is
INCREASED . Therefore, the rate of weathering is FASTER.
Particle size  large
Almost all the sand grains you see are quartz. Why does quartz make up such
a large portion of sand? QUARTZ IS MOSTLY UNEFFECTED BY CHEMICAL WEATHERING
In what type of climate is chemical weathering most pronounced? WARM & HUMID
What does most pronounced mean? What are other terms (synonyms)? DOMINANT
What type of weathering is dominant in cold climates? FROST ACTION
When does frost action become especially intense? IN MOIST CLIMATES THAT LEAD TO
REPEATED CYCLES OF FREEZING AND THAWING
Notice moisture is a key factor for both chemical and physical weathering!
Soil Formation (p.160)
Define Soil: MIXTURE OF ROCK PARTICLES AND ORGANIC MATTER
Define Humus: NUTRIENTS FOR PLANTS – DECAYED ORGANIC MATTER
Humus is mostly in topsoil.
If the minerals in the soil match the minerals of the local bedrock, then the soil is residual.
If the minerals in the soil DO NOT match the minerals of the local bedrock then the soil is transported.
Are most of the soils covering NYS residual or transported? TRANSPORTED
In NY, what was the driving force behind getting sediment particles of soil to there current location?
GLACIERS
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Name: _______________________
Topic 9: Weathering & Erosion (pp.157 – 170)
Now answer questions 1-10 on p. 161.
Erosion (p.161)
The transport of weathered sediment is called EROSION
Transporting Systems of Erosion (p.161)
The first component of a transporting system is an AGENT OF EROSION. List the six examples given:
STREAM, GLACIER, WAVE, CURRENT, WIND, HUMAN ACTIVITY
What does the term AGENT OF EROSION mean? WHAT’S DOING THE EROSION
What is the driving force behind most of the agents of erosion? GRAVITY
The last sentence on p.161 starts with the word Insolation. What does this word refer to? Read the first couple of
sentences of the paragraph before you write your answer down.
SUNLIGHT
Gravity Erosion (p.162)
Define Mass Movements: EROSION BY GRAVITY
What are the two fundamental forces involved in mass movements? GRAVITY & FRICTION
Carefully examine figure 9-5. What are the main differences between soil creep, debris flow, mud flow, and
rock falls? SPEED OF THE MOVEMENT
How can this difference be inferred from the illustrations that go with each variety of mass movement?
SLOPE, STEEPNESS, OR GRADIENT OF THE HILL
Running Water Erosion and Streams (p.162)
What is a rill? A TEMPORARY STREAM
What other term is more commonly used to describe this feature? GULLY
According to this book, what is a stream? RUNING WATER CONFINED TO A CHANNEL
A small stream that flows into a larger stream is called a TRIBUTARY .
Streams carry sediment in three ways. Dissolved minerals are carried in SOLUTION. Solid sediments of small
size – including clay-sized sediments – are carried in SUSPENSION in the water. Larger solid sediments are
usually carried by rolling, sliding, or bouncing along the stream bottom, resulting in rounding of sediments by
STEAM ABRASION .
Rivers create V-Shaped Valleys. What actions combine to create the V-shaped valley of a river?
DOWNCUTTING, RUNOFF, & MASS MOVEMENT
What is a watershed? THE AREA OF LAND DRAINED BY A STREA, What separates one watershed from
another? DIVIDES
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Name: _______________________
Topic 9: Weathering & Erosion (pp.157 – 170)
Stream Velocity (p.163).
The 3 factors that control a stream’s average velocity are:
1. GRADIENT
2. DISCHARGE
3. SHAPE OF THE CHANNEL
What is a streams gradient? SLOPE OR STEEPNESS OF THE LAND
What is a streams discharge? VOLUME OF WATER FLOWING THROUGH THE STREAM.
The stream channel shape controls the amount of surface area (perimeter in figure 9-8) between the water and
the ground. With more surface area between the water and the ground there is more friction or drag and
turbulence slows the streams velocity.
FIGURE 9-9 IS VERY IMPORTANT! YOU MUST LEARN IT.
If a stream channel is straight, where is the fastest flowing water? CENTER
Where is the fastest flowing water when a stream channel curves? ON THE OUTSIDE OF THE CURVE
Figure 9-10 is almost exactly the same diagram from p.6 of your ESRT. Be able to use the chart what velocity of
water will transport what kind of sediment. For example, a stream traveling with an average velocity of 200
cm/sec can transport what sizes of sediment? (some cobbles, pebbles, sand, silt and clay)
Evolution of a Stream (p.165)
In the early stages of the stream, most of its energy is used to DOWNCUT a narrow V- SHAPED valley. There
is usually a STEEP slope and many abrupt changes in elevation resulting in WATERFALLS and RAPIDS .
As the stream grows larger, it begins to shift its course in a series of bends or turns called MEANDERS .
What is a Delta? Where does it form? AT THE END OF A STREAM (MOUTH) SEDIMENT IS
DEPOSITED IN A FAN SHAPE CALLED A DELTA
Glacial Erosion (p.166)
Define a glacier. NATURALLY FORMED MASS OF ICE & SNOW THAT MOVES DOWNHILL UNDER
THE INFLUENCE OF GRAVITY.
What are the two types of glaciers? CONTINENTAL ICE SHEETS & MOUNTAIN (ALPINE) GLACIERS.
What has to happen in order for a glacier to advance? MORE SNOW MUST FALL AND ACCUMULATE
THEN SNOW AND ICE MELTS AT THE TIP OF THE GLACIER
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Name: _______________________
Topic 9: Weathering & Erosion (pp.157 – 170)
How are glacial grooves and glacial parallel scratches (usually called STRIATIONS) formed? ROCKS AT
THE BOTTOM OF THE GLACIER GOUGE THE BEDROCK BENEATH THEM
Recent research contradicts information printed on p.167. The book says that large glacial sediment, called
erratics, can be transported hundreds of miles. This is not true. It is now believed that large boulders cannot
travel more that 20 – 30 miles.
Rivers and streams create V-shaped valleys. What is the shape of a glacier valley? U-SHAPED VALLEY
Figures 9-13 and 9-14 are important!
Wave and Current Erosion (p.168)
What is a long shore current (look at figure 9-16B—the zig zag motion of sand)? Why doesn’t it exist if waves
strike the beach head on? THIS IS THE CURRENT THAT PUSHES SAND ALONG THE SHORE. If THE
WAVES STRIKE THE BEACH HEAD ON, THERE IS NO LATERAL (SIDEWAYS) FORCE TO PUSH
THE SAND GRAINS ALONG THE SHORE.
Sediment Features and Erosional Agents (p.168)
Learn figure 9-17!
Describe the sediment eroded by a stream: SMOOTH & ROUND
Describe the sediment eroded by wind: ROUNDED & FROSTED
Describe the sediment eroded by ice: SUB-ROUNDED & SCRATCHED
Describe the sediment eroded by gravity: SHARP & ANGULAR
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