Name: ______________________
Date: _______________________
Geography 12
Teacher Key
Coastal Landscapes
Chapter 14 – Planet Earth: A Physical Geography (p.291-298)
1) Describe how coastal landscapes are quite unique when compared with other distinctive
landscapes.
Not associated with special climatic or bedrock conditions like the other distinctive
landscapes; extend only a short distance inland and out into the ocean, sea, or lake.
2) How do waves and currents form?
The sun is the source of most of the energy that drives coastal processes. This energy
takes a rather long path to reach shoreline, beginning as solar energy entering the
atmosphere. This creates differences in heating and thus pressure from one location to
another. Wind is simply air moving from a place of high air pressure to a place of low
air pressure. The greater the difference in air pressure, the stronger the winds.
The resulting winds transfer some of their energy to the surface of the water to form
waves and currents.
3) Define breaker.
An over steepened wave that falls over on itself, spending its energy against the
shoreline.
4a) Explain why waves, in most cases, do not approach the coastline straight on but rather at
an angle other than 90 degrees.
Waves move onto a coastline at an angle due to bending around headlands and looping
into bays (an irregular coastline) or wave crests approaching a straight coastline are
slowed by frictional drag on the bottom and begin to bend as the outer sections of the
wave, still in deeper water, continue at their normal speed or due to prevailing winds
approaching the coastline at an angle other than 90 degrees.
b) While the waves may approach the coastline at an oblique angle, they return straight
back to the sea under the force of gravity. Hence, if one was to release a beach ball a short
distance from the coastline, it would follow a zigzag pattern of movement as illustrated in
the diagram below. Similarly, sand and pebbles would be carried along in such a fashion.
This current that moves down a coastline within the shallow breaker zone next to the
shoreline is known as longshore drift.
c) A concern regarding this net transport of materials down the coastline is the loss of sand
from a beach. To combat this, structures are built perpendicular to the coastline to try to
keep sand in place. These structures, shown in the pictures below, are known as groynes or
groins.
Courtesy: P. Mleziva
Courtesy: P. Mleziva
Courtesy: P. Mleziva
5) Define headland.
A point of land that extends outwards into a body of water from a coastline; often
having a steep cliff face.
Major Processes of Erosion by Waves
6a) Abrasion, also known as corrasion, occurs as waves hurl bits of rock and sand against
cliffs and headlands.
b) Describe hydraulic pressure.
Water hurled at great speeds against rock surfaces, during storms, puts pressure on
fractures or other weak points in the rocks, breaking off fragments. These fragments
then act as cannon balls for the process of abrasion / corrasion.
c) Attrition occurs when rock fragments broken away from the rock surfaces hit against
each other and erode into smaller fragments.
d) Describe corrosion.
Occurs when soluble minerals are dissolved by water. Such action is common on
limestone headlands, especially when the water is slightly acidic.
7) Answer Question #23 on page 297 in Planet Earth: A Physical Geography. Include the
terms cave, arch, and stack in your explanation.
See Planet Earth: A Physical Geography Teacher’s Guide.
8a) Describe the formation of a wave-cut platform.
Wave action cuts at the base of the cliff, undermining the cliff until it collapses. Wave
action soon removes the debris, and undercutting continues. Continued erosion causes
the cliff to recede farther, leaving a gently sloping wave-cut platform. Some of the
sediment eroded from the shore can be deposited in deeper water, forming a
complementary wave-built terrace.
b) Insert an image of a wave-cut platform from the internet. Include the exact website
source.
Sources and images will vary.
9) To prevent erosion of the coastline or to shelter boats from strong waves, breakwaters
are built. These can be large piles of rocks or other objects placed parallel to the coastline to
help break the force of the incoming waves. Insert an image of a breakwater from the
internet. Include the exact website source.
Sources and images will vary.
Deposition by Waves
10) Define the following terms and look at figures 14.18 and 14.19 carefully.
Insert an image for three of the following items from the internet. Include the exact website
source.
a) bayhead beach: a deposit of sand formed at the head of a bay through wave action,
usually along an irregular coastline.
b) spit: a sand bar, formed by wave action, extending out into a body of water that is
attached to land only at one end.
c) baymouth sand bar: a deposit of sand forming a narrow band linking two
headlands across the mouth of a bay on an irregular coastline.
d) tombolo: a sea stack or small island attached to the mainland by a sand bar.
e) barrier island or offshore bar: a long deposit of sand which forms parallel to the
coastline and is separated from it by a lagoon.
Describe the two methods of origin given for the formation of barrier islands / offshore bars.
- offshore bars are spits that have extended long distances along a shoreline from a
headland over thousands of years.
- a rise in sea level following the melting of ice age glaciers; as the sea rises, it floods a
sand ridge formed on a former beach by wind action, creating an offshore bar or
barrier island, separated from the mainland by a lagoon.
f) lagoon: the coastal water body separating a barrier island or offshore bar from the
mainland or the water trapped behind a baymouth sand bar.
Tides
11) What are tides and how do they occur?
Tides are the regular rise and fall of sea level that occur on most of the world’s
seacoasts due to the gravitational attraction of the moon and the centrifugal force of the
earth’s rotation.
12) Answer Question #27a and b on page 298 in Planet Earth: A Physical Geography.
See Planet Earth: A Physical Geography Teacher’s Guide.
Classifications of Coastlines
13a) Recall from the Glacier unit that U shaped valleys leading down to the sea that have
been drowned as a result of a rise in sea level are known as fiords.
British Columbia has this type of coastline.
b) V shaped valleys leading to the sea that have been drowned as a result of a rise in sea
level are known as rias.
c) A longitudinal coastline involves folded mountains and valleys that are parallel to the
coastline.
Coral Reefs
14) Coral reefs occur in warm tropical waters where soft-bodied creatures, known as corals,
produce a skeleton of calcium carbonate; when these creatures die, their skeletons form a
foundation upon which new corals can grow resulting in the continual growth of the coral
reef.
Insert an image of a coral reef from the internet. Include the exact website source.
Sources and images will vary.
An atoll is a Pacific circular reef enclosing a lagoon.
Emerged versus Submerged Shorelines
15) Emerged Shorelines: the land has risen; the water has become shallower.
Significance to Humans
Pros: newly emerged coastal plain potentially offers an area of land for agricultural
settlement; beaches and / or lagoons develop into resort areas.
Cons: difficult for commercial shipping because of offshore bars and few deep water ports
16) Submerged Shorelines: land has sunk and / or the water has risen.
Significance to Humans
Pros: Irregular coastlines offer sheltered, deepwater harbours which are excellent for ports
Cons: Irregular coastlines hinder land transportation along the coast and rough terrain
hinders human settlement
Which one of the following features would not be associated with a submerged coastline? d
a) rias
b) fiords
c) spit
d) offshore bar e) baymouth bar
Coastal Landforms on Topographic Maps
17) Match each term with the appropriate topographic map below.
a)
b)
c)
d)
sea stacks
headland
baymouth bar
tombolo
1) c
e) offshore bars
f) spit
g) wave-cut platform
2) b
3) e
4) a
5) f
6) d
7) g