2. What's expected for today
By the end of this lesson, you should be able to:
Explain how headlands and bays are formed with
the help of well-labelled diagrams
Draw clear diagrams in boxes with:
− Labels
− Title
3. Textbook p. 144
Headlands and bays
Headlands and bays form along a coast that is made
up of bands of rock with
v a r y ing r e s i s t a n c e to erosion.
This means that, the rate at which a coast is eroded
depends partly on rock resistance.
4. Textbook p. 144
Headlands and bays
More resistance rock → the faster/slower it takes for
waves to erode it
Less resistant rock → the faster/slower it takes for
waves to erode it
5. 1.3 Formation
Wave energy is concentrated at the headlands
because the waves bend as they approach the
protruding headlands.
This is due to the waves slowing down as they reach
the shallower waters in front of the headlands while
other waves not affected by the headlands continue
ahead at the same speed. [1]
6. 1.3 Formation
different rate of erosion of rocks along the coast
produces an uneven coastline
- less resistant rocks curve inwards, forming bays
(Y)
- while the more resistant rocks will protrude out
from the coastline, forming headlands (X)
7. Textbook p. 144
1.1 Some specifics
Granite and basalt are examples of more resistant
rock.
8. Textbook p. 144
1.1 Some specifics
Chalk, sandstone, and shale examples of less
resistant rocks.
9. Textbook p. 144
1.1 Some specifics
What are some of the places where headlands and
bays can be found?
This is Homework Part 1: due tomorrow (April 3,
Tuesday).
10. Textbook p. 145
1.2 Wave refraction
Wave refraction refers to the bending of waves because
of differences in wave speeds.
11. Textbook p. 145
1.2 Wave refraction
Waves bend and slow down as they approach the
protruding headlands.
Because they encounter friction with the
increasingly shallow seabeds in front of these
headlands
12. Textbook p. 145
1.2 Wave refraction
Wave refraction causes headlands to be the
focus of wave energy and thus the focus of
erosion.
Wave energy is weakened along the wider
stretches in the bays, so waves deposit
sediments at bays.
13. Textbook p. 144
1.3 Formation
Less resistant rock Bay
At a coast where
resistant rocks alternate
More with less resistant
resistant rock
rocks,
Headland
the less resistant rocks
are eroded at a faster
rate than the resistant
rocks.
More resistant rock Headland
Figure 1: Formation of headlands and bays
14. Textbook p. 144
1.3 Formation
The different rates of
erosion along the coas
produces an uneven
coastline.
15. Textbook p. 144
1.3 Formation
The less resistant rocks
curve inwards, forming
bays,
while the more resistant
rocks protrude from
the coastline, forming
headlands.
16. Homework
Part 1
Complete asterisked (*) question under 1.2 Some
specifics
Part 2
Read textbook pages 146-148 for tomorrow's lesson
on beaches, spits and tombolos.
17. Looking back and ahead...
1. Coastal processes 2. Coastal landforms
Erosion ✔ Cliff & shore platform ✔
Deposition ✔ Headland and bay ✔
Longshore drift ✔ Beach
Spit
Tombolo
3. Coastal engineering
18. What's expected for today
By the end of this lesson, you should be able to:
Explain how a coastal SPIT is form with the help
of well-labelled diagrams
Predict what a spit would turn into if there is an
offshore island nearby - TOMBOLO
Draw clear diagrams in boxes with:
− Labels
− Title
19. Depositional Landforms
In addition to shore platforms there are three
other types of depositional landforms.
Beach
Tombolo
Spit
20. Beach
A beach is the result of constructive waves
depositing material on the coast.
Swash is stronger than backwash
Waves have energy to bring material upshore but not
back into the sea
