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FACTORS THAT AFFECT THE FACTORS THAT AFFECT THE RATE OF WEATHERINGRATE OF WEATHERING
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1.1. Mineral CompositionMineral CompositionThe harder the rock, the slower the rate The harder the rock, the slower the rate of weatheringof weathering
Composition dictates hardness which Composition dictates hardness which determines resistance to weathering.determines resistance to weathering.
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WHICH LAYER IS MORE WHICH LAYER IS MORE RESISTANT TO WEATHERING?RESISTANT TO WEATHERING?
LEAST RESISTANT?LEAST RESISTANT?
A
BC
D
Which rock is most resistant to weathering?
Which rock is 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…
Welcome to Huntington Cemetery!
Step inside- IF YOU DARE- CREEPY
Wow! We haven’t even stepped inside and we have evidence of weathering in the gate!
What process is this and is it physical or chemical?
We are going to look at cemetery rocks…(tombstones!) and observe the weathering that has occurred in them.
Since tombstones are dated we can even determine how long the weathering has occurred!
Here is a typical marble tombstone which used to be a very popular rock for cemeteries.
What mineral largely composes the rock marble?
Calcite is very unstable at the earth’s surface in certain climate types. Which type in particular?
What weathering process causes the tombstones to “dissolve”? Is this chemical or physical?
CO2 CO2
Carbonation
Here is another type of tombstone. It is made up of slate.
Compare the two tombstones in the next picture. How do they differ in terms of the types of weathering that has occurred to each?How do they compare in appearance? Which appears more weathered?
Marble Slate
Marble Slate
Which tombstone is older?
Marble Slate
This means that rocks can weather at different rates!
This is called “Differential Weathering”Rocks weather at different rates due to differences in mineral composition.Some minerals are more stable at the earth’s surface than others! These take longer to weather.
Factors Affecting Weathering RatesFactors Affecting Weathering Rates2. EXPOSURE
- THE LONGER Weathering takes place on the outside surface of rocks. The more _____________ that occursWeathering
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Factors Affecting Weathering RatesFactors Affecting Weathering Rates
As a rock breaks into As a rock breaks into smaller pieces, the smaller pieces, the ____________ area ____________ area increases, therefore the increases, therefore the rate of weatheringrate of weathering ___________.___________. Which will weatherWhich will weather
The fastest?The fastest?
3. Particle Size- Weathering takes place on the outside surface of rocks. So the more _____________ that is exposed to weathering, the faster the rock will be broken down.
surface area
surface
increases
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Surface AreaSurface Area
Which will weather faster, solid rock Which will weather faster, solid rock or crushed rock? Why??or crushed rock? Why??
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The answer and explanation on next page
The crushed rock The crushed rock of course!of course! The large rock is The large rock is
tightly packed tightly packed and has less and has less surface area surface area exposedexposed
The crushed rock The crushed rock is loosely packed is loosely packed and has more and has more exposed.exposed.
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Factors Affecting Weathering RatesFactors Affecting Weathering Rates4.4. ClimateClimate
#1 factor in weathering process#1 factor in weathering process Dictates temperature and amount of Dictates temperature and amount of
moisturemoisture
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Climate-
1. Temperature:a. In warm climates ____________is the dominant
type of weathering.b. In cold climates ____________ is the dominant type of weathering.2. Precipitation:
a. As precipitation increases, the amount of weathering by frost action will __________.b. As precipitation increases , the amount of chemical weathering will__________________.
3. Chemical weathering is most rapid in __________, __________ climates.
chemical
physical
increase
increase
warmmoist
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How does climate affect How does climate affect weathering?weathering?
Physical WeatheringPhysical Weathering Works better in a Works better in a
cool and moist cool and moist climateclimate
Chemical WeatheringChemical Weathering Works better in a Works better in a
hot and moist hot and moist environmentenvironment
More water = more More water = more weatheringweathering
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WHICH DIAGRAM IS AN ARID WHICH DIAGRAM IS AN ARID CLIMATE? HUMID CLIMATE?CLIMATE? HUMID CLIMATE?
A B
Humid – more rounded
Arid – more angular
Sharp cliffsNo
vegetation
Rolling hillsvegetation
_________Climate
________Climate
humid arid
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WHAT KIND OF CLIMATE WHAT KIND OF CLIMATE SUPPORTS WEATHERING?SUPPORTS WEATHERING?
COLD →→→→→→→→→→→→→→→→→→→→→→ HOT
HIGH
PPT
↑
↑
↑
↑
↑
↑
↑
↑
LOW
PPT
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Answers to Weathering and Climate WorksheetAnswers to Weathering and Climate Worksheet
HH Yakutsk, USSR (-12 Yakutsk, USSR (-12°,31cm)°,31cm)FF Yuma, Arizona Yuma, Arizona (22(22°,8cm)°,8cm)BB Minneapolis, Minnesota (5 Minneapolis, Minnesota (5°,67cm)°,67cm)DD Charleston, S. Carolina (19 Charleston, S. Carolina (19°,123cm)°,123cm)AA Middletown, Connecticut (10 Middletown, Connecticut (10°,95cm)°,95cm)GG Anchorage, Alaska (0 Anchorage, Alaska (0°,37cm)°,37cm)EE Monterey, California (13 Monterey, California (13°,52cm)°,52cm)CC Belize City, Belize (25 Belize City, Belize (25°,200cm)°,200cm)
Answers to Weathering and Climate WorksheetAnswers to Weathering and Climate Worksheet
1)1) Warm and moist. The rate of chemical Warm and moist. The rate of chemical weathering increases, as temperature weathering increases, as temperature and moisture increasesand moisture increases
2)2) Moist climate with alternating periods Moist climate with alternating periods of freezing and thawingof freezing and thawing
3)3) Very dry or arid climateVery dry or arid climate
Answers to QuestionsAnswers to Questions
1)1) DD
2)2) DD
3)3) DD
4)4) CC
5)5) CC
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6)6) BB
7)7) BB
8)8) CC
9)9) AA
10)10) DD
11)11) BB
Answers to QuestionsAnswers to Questions
12)12) DD
13)13) DD
14)14) DD
15)15) AA
16)16) DD
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17)17) CC
18)18) BB
19)19) AA
20)20) DD
21)21) DD