Chapter 2: Weathering (Notes)
By the end of this section, you will be expected to demonstrate an understanding of
how the process of weathering helps wear down the land, including the following:
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1.2.1 Distinguish between the terms physical weathering and chemical
weathering. (k)
1.2.2 Describe the mechanical processes by which physical weathering
occurs. (k)
1.2.3 Describe the main interactions that result in chemical weathering. (k)
1.2.4 Infer how the relationship between environmental conditions and the
rate of physical and chemical weathering. (a)
Overview
Chapter 1 introduced us to many of the extreme forces & processes that shaped the
landforms around us volcanoes / earthquakes are the results of tectonic forces at
play within our earth bringing sudden & violent change our focus in this chapter will
be to examine two wearing-down forces that cause gradual changes to our many
landforms river water and glacier ice is our focus.
Denudational Processes
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________________ are a part of a complex interrelationship that involves
the wearing away of the Earth’s surface
Forces such as ______, ________, ________, ________, & ______ cause
erosion
Denudation is a term that refers__________________________________
____________________________________________________________
Forces that cause denudation are also called _________________ processes
because they tend to grade the earth’s surface making it level
Weathering vs. Erosion
Denudation involves two types of processes: ___________________&_________
Weathering is the ___________________________________________________
__________________________________________________________________
(It turns solid rock masses into loose materials such as rock fragments, sand, soil)
______________ is a two-part process that starts with (1) breakdown of rocks &
minerals(weathering) & also includes the movement (transportation) of these
weathered materials. (2) _____________ of the eroded material which occurs
when it is dropped in a new location.
World Geography 3200
October 7, 2013
Chapter 2: Weathering (Notes)
Physical Weathering vs. Chemical Weathering
Physical weathering is ______________________________________________
__________________________________________________________________
__________________________________________________________________
Types of Physical Weathering
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_____________________: Occurs when water seeps into the fractures of
rocks, freezes, & ultimately expands splitting rocks apart. Ex: our highways
in winter & freezing temperatures
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______________________: In areas when temps _________________
greatly from day to night or from season to season, temp change can cause
physical weathering. Ex: sudden heat causes rocks to expand while sudden
cooling causes rocks to contract
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Plant growth: ___________________________________________
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Burrowing animals: tunneling animals can __________________ the size
of _______________________________ in rocks as they tunnel through
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__________________: as ____________ ________________ is released
from certain rocks, it can cause layers_______________________________
_______________ in rounded sheets like the layers of an onion.
Environment's Affect on Physical Weathering

Fast temperature changes like those that occur in the __________ increases
the amount of _________________________ due to
________________________________. Conversely, for regions like the
tropics where there is little temperature change, the amount of physical
weathering due to heat expansion is minimal.
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Abundant ______________________ combined with alternating
_________________________________ temperatures increases the
amount of frost fracture. Conversely, the absence of those climatic conditions
reduces the amount of frost fracture.

_____________________________ increases physical erosion as
_____________ occurs between water and rock.
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Ocean waves cause _____________________________ and
_____________ on the shore leading to physical weathering.
World Geography 3200
October 7, 2013
Chapter 2: Weathering (Notes)
A Quick Review
1. The term that refers to the breakdown of rocks and minerals.
2. The term that refers to the breakdown, transportation and deposition of rock
and minerals.
3. Weathering that relies on mechanical processes/forces to break down rock
and minerals.
4. Weathering that relies on chemical processes to break down rock and
minerals.
5. Physical weathering that causes rocks to break off due to internal pressure.
6. Physical weathering that causes rocks to break due to freezing water
expanding in rock cracks.
7. Physical weathering that causes rocks to break due to fast changes in
temperature.
Types of Chemical Weathering
Chemical weathering is the __________________________________________
__________________________________________________________________
__________________________________________________________________.
There are three different types of chemical weathering described below.
 The formation of ________________________ as rainwater absorbs CO2 ,
SO2, and other chemicals from the atmosphere along with organic acids
from the soil which then reacts with rock and minerals causing some to
dissolve and move away.
 _____________________, like the first process, involves the minerals in
solution. In this case, carbonic acid reacts with silicates in some rocks
leaving a soft clay from which potassium, sodium and magnesium are
subsequently leached.
 ___________________ is the reaction of metallic minerals to oxygen
(mainly in water). This results in the formation of oxides, which tend to be
softer than the original mineral. For example, rust on iron.
World Geography 3200
October 7, 2013
Chapter 2: Weathering (Notes)
How Environmental Conditions Affect Chemical Weathering
 Heavy rain, running water and abundance of water increases the amount of
dissolving that occurs. Conversely less abundance of water leads to less
dissolving.
 High temperatures will increase the rate of chemical reactions. It is a fact of
chemistry that heat increases the speed of many reactions like oxidation.
 Ocean water contains salt which can increase the rate of many reactions like
oxidation.
A Quick Review (Chemical Weathering)
1. Which type of chemical weathering involves organic acids dissolving minerals
allowing them to move away from the parent rock?
2. Which type of chemical weathering involves organic acids dissolving silicate
causing the formation of soft clay which can easily be leached away?
3. Which type of chemical weathering involves the formation of oxides, often in
the presence of water, which tend to be softer than the original mineral?
4. What affect would high ambient temperature have on the rate of chemical
weathering?
5. What affect would an extreme lack of water, like desert conditions, have on
the rate of chemical weathering?
6. What affect would heavy wind have on the rate of chemical reactions?
7. How does the presence of ocean water affect the rate of chemical
weathering?
World Geography 3200
October 7, 2013