Chapter 12 Objectives:
Geography 12
Worksheet 12
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Key
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Denudation: Weathering and Mass Wasting
Read pages 241 – 251 of Planet Earth: A Physical Geography. Answer
the following questions:
Vocabulary (1 mark each)
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denudation: the range of agents that work constantly to lower the earth’s surface to a
common level
Base level: the lowest level to which a land surface can be eroded….sea level
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Determine the meaning of
the terms associated with the
processes that work to lower
the surface of the earth;
Understand that the end
product of denudational
processes is the general
leveling of the earth’s
surface to sea level;
Apply a classification
system for the two types of
weathering, physical and
chemical, and the various
processes that operate under
each type;
Understand the conditions
that affect the rate and
distribution of weathering
processes;
Determine the nature of
mass wasting and the
influence gravity has on the
movement of weathered
materials.
Degradation: the process of lowering the earth’s surface by the processes of weathering, erosion, and
transportation
Weathering: the disintegration or decomposition of rocks in place on or near the earth’s surface
Erosion: the removal and movement of rock debris and associated organic matter from one part of the
earth’s surface to another through agents such as running water, ice, waves, and wind.
Aggradation: the processes that build up the land surface through the deposition of rock materials
Deposition: the dropping of rock materials that occurs when a drop in energy slows a transporting
agent, such as running water, wind, or waves.
Physical weathering: the mechanical disintegration or fragmentation of rocks into smaller particles
with little change in their chemical composition
Frost shattering: the splitting apart of rocks by the freezing and expansion of water in fractures and
joints; common in high altitude and high latitude regions where the temperatures frequently rise and fall
about the freezing point
Thermal expansion: the disintegration of rocks caused by the differential heating and cooling of
different minerals within them; common in granitic rocks in desert environments
Chemical weathering: the chemical decay or alteration of rocks by a change in their chemical
composition
Oxidation: a form of chemical weathering in which oxygen combines with certain minerals in the rock
to form oxides and hydroxides and leading to the disintegration of the rock
Hydrolysis: a form of chemical weathering in which water combines with minerals to form hydroxides
that expand and eventually cause the disintegration of the rock
Mass wasting: the downhill movement of weathered materials caused by the pull of gravity
Solifluction: the slow, downhill movement of water-saturated rock and soil material; commonly occurs
in summer in high latitude climates where the sol is underlain by permafrost
Rock glaciers: the slow, downhill movement of large volumes of rock fragments, especially in midand high latitude mountains where frost shattering, or ice wedging, is common
Rock slide: the rapid slide of large sections of rock in steeply sloping mountain areas
Slump: the rotational slip of a block of soil and rock along a concave surface; common in wet, clay
soils
Talus: a fan-shaped pile of rock fragments that accumulates at the base of steep slopes in mountain
regions where frost shattering is common
Short Answer (2 marks each)
1. Where does the energy fro denudation come from? (1 mark)
-above
2. Briefly describe the 2 types of denudation? (2 marks)
-degradation – weathering and erosion and transportation. The disintegration and movement of
rock
-aggradation – the building up of land surface by the deposition of rock
-deposition is when the rock is deposited or built up during transportation
3. What are th 2 types of weathering? (2 marks)
- physical and chemical
4. Give an example of physical weathering for each of the following. ie: explain the
process in your own words. (5 marks)
-frost shattering
-thermal expansion
-pressure release
-animals and plants
-crystal growth
5. Gove an example of chemical weathering for each of the following. ie. Explain
the process in your own words. (3 marks)
-solution
-oxidation.
-hydrolysis
6. What are the two most important factors that affect the rate, depth and degree of
weathering? Why?(2 marks)
-temperature – because they control the intensity of weathering activity
- precipitation- because it provides water, an effective agent in breaking down rocks and minerals
7. Explain the 2 factors affecting mass wasting. (2 marks)
-friction – water and ice fill pores in soil and lessen the cohesion allowing them to slide past one
another.
-gravity – determined by the steepness of the slope and thickness of loose material. The greater the
slope, the greater the force, the greater the mass of rock, the greater the speed it slides.