Conceptual Understanding:
Key Question:
How are coastal places shaped by their interactions with oceans?
Key Content:
- Physical influences on coastal landscapes, including waves, tides, sediment supply, lithology, vegetation, subaerial processes and wave processes (littoral drift, hydraulic action and attrition).
- The characteristics and formation of coastal landforms as a result of erosion and deposition, including wave-cut platforms, cliffs, stacks, spits and beaches.
- The formation and identification of advancing and retreating coastlines, including isostatic and eustatic landforms (relict cliffs, raised beaches, fjords).
- The role of coastal processes, wind and vegetation in coastal sand dune development.
Thursday 05 October 2023
Physical Processes on Coastal Landscapes
Starter: On the 10 photos of different coastlines that are on the desks identify as many coastal features or processes that you know of.
Coastal environments are influenced by many factors and shaped by a variety of physical and human processes. As a result there is a great variety in coastal landscapes.
- Lithology properties (type of rock)
- Geological structure (concordant – strata is parallel to the coastline or discordant coastlines – strata is at right angles to the coastline)
- Erosional and deposition processes
- Sea level changes (advancing and retreating coastlines)
- Human impacts (modifications on the coast)
- Ecosystem type (mangroves, corals, sand dunes, salt marshes)
Main Activity:
You are each going to investigate a different process that is occurring at the coastline and create a 15-20 minute lesson that you will teach to the rest of the class. You need to be responsible for deciding how best to present this information to the class and create any materials that the class will need. I will print off any resources that you may need if you tell me in advance.
- Types of wave and tides and Longshore Drift (Hannah)
- Factors influencing the type of wave
- Characteristics of destructive and constructive waves
- Wave refraction
- Characteristics of tides
- Definition of Longshore Drift
- Explanation of the process
- Subaerial weathering processes (Julia)
- Salt weathering
- Physical weathering (freeze-thaw)
- Chemical weathering
- Biological weathering
- Water layer weathering
- Wave erosion processes (David)
- Abrasion
- Hydraulic action
- Solution
- Attrition
You will have today’s lesson to complete this.
Success Criteria:
- Instruction/theory presented in a format that can be given to the class
- An activity for the class to do
- Use of images/maps/diagrams
- Student engagement
- Six useful MCQ’s to test knowledge that I can use in a quizziz
Thursday 10 October 2023
How do waves create coastal landforms of erosion and deposition?
There are four main coastal landforms that we are going to study today:
- Cliffs and wave cut platforms (erosional landform)
- Headlands and bays (erosional landform)
- Caves, arches, stacks and stumps (erosional landform)
- Spits and bars (depositional landform)
Task 1.
- Study the cards that you have been given.
- Sort them into three piles according to the type of landform that they show. There will be 1 card showing a photograph of a landform and additional cards that show the process of how that landform was created.
- Sequence the cards together to show the formation of the landforms.
Task 2.
Option 1.
- Study the four photographs given.
- Determine which of the above coastal landforms they show.
- Annotate them with at least 6 annotations each explaining how the feature has been formed.
- You must use at least one of the following key statements/words below in each annotation. Each statement/word can be used more than once.
- Aim to use all of the key statements/words across all of your annotations.
Option 2.
- Using the modelling clay provided, create a sequence showing the formation of Two of the landforms above.
- Annotate them with at least 6 annotations each explaining how the feature has been formed.
- You must use at least one of the following key statements/words below in each annotation. Each statement/word can be used more than once.
- Aim to use all of the key statements/words across all of your annotations.
Key statements/words:
- Hydraulic action
- Attrition
- Abrasion
- Wave refraction
- Subaerial processes
- Erosion
- Deposition
- Beach
- Spit
- Bar
- Longshore drift
- Wave-cut notch
- Wave-cut platform
- Headland
- Cliff
- Bay
- Cave
- Arch
- Stack
- Stump
- Destructive wave
- High energy
- Discordant coastline
- Collapses
- Retreats
Monday 16 October 2023
What processes allow coasts to advance and retreat and what are the resulting landforms?
Lesson Objectives:
- To explain the advance and retreat of coasts including th role of isostatic and eustatic processes.
- To describe and explain the associated landforms including relict cliffs, raised beach and fjords.
Starter: Study the following photograph of series ridges or beaches at Turakirae Head, near Wellington, New Zealand, and suggest reasons for the raised beaches shown
Isostatic Sea Level Changes
Isostatic sea level change is the result of an increase or decrease in the height of the land. When the height of the land increases, the sea level falls and when the height of the land decreases the sea level rises. Isostatic change is a local sea level change.
During an ice age, isostatic change is caused by the build up of ice on the land. As water is stored on the land in glaciers, the weight of the land increases and the land sinks slightly, causing the sea level to rise slightly. This is referred to as compression. When the ice melts at the end of an ice age, the land begins to rise up again and the sea level falls. This is referred to decompression or isostatic rebound. Isostatic rebound takes place incredibly slowly and to this day, isostatic rebounding is still taking place from the last ice age.
Isostatic sea level change can also be caused by tectonic uplift or depression. As this only takes place along plate boundaries, this sort of isostatic change only takes place in certain areas of the world.
Eustatic Sea Level Changes
Eustatic change is when the sea level changes due to an alteration in the volume of water in the oceans or, alternatively, a change in the shape of an ocean basin and hence a change in the amount of water the sea can hold. Eustatic change is always a global effect.
During and after an ice age, eustatic change takes place. At the beginning of an ice age, the temperature falls and water is frozen and stored in glaciers inland, suspending the hydrological cycle. This results in water being taken out of the sea but not being put back in leading to an overall fall in sea level. Conversely, as an ice age ends, the temperature begins to rise and so the water stored in the glaciers will reenter the hydrological cycle and the sea will be replenished, increasing the sea levels.
Increases in temperature outside of an ice age will also effect the sea level since an increasing temperature will cause the ice sheets to melt, putting more water in the sea.
The shape of the ocean basins can change due to tectonic movement. If the ocean basins become larger, the volume of the oceans becomes larger but the overall sea level will fall since there’s the same amount of water in the ocean. Conversely, if the ocean basins get smaller, the volume of the oceans decreases and the sea level rises accordingly.
Wednesday 18 October 2023
What coastal processes help dunes develop?
Lesson Objectives:
- To examine the role of coastal processes, such as waves, wind and vegetation in the development of sand dunes.
Starter:
Study the photograph and discuss how the following factors influence dune formation:
- Wind
- Waves
- Beach
- Sediment supply
- Relief
Sand Dune Formation
Dunes form typically on large flat beach profiles with a large sediment supply to the backshore. Dunes develop in a different way to other depositional features because they are the result of the interaction between marine processes and the atmosphere. In brief, dunes begin to form beyond the strandline of the beach where dry sediment is transported by wind through saltation and suspension. Beach litter and debris that collects on the storm beach acts as an obstacle to saltation and sediment begins to build up. Over time, an embryo dune develops, which may become vegetated by marram grasses. Vegetation stabilizes the dunes in two ways. Firstly, the roots bind the sand together, and secondly the above ground vegetation traps particles of sand as they are blown over the surface. When dunes are less vegetated they remain unstable and so they migrate.
Wind and Sand Dune Development
Dunes have a typical form, the windward side is gentle sloping and shaped my wind movement. The leeward side faces away from the shore and is steeper and unstable. Dunes increase in size inland. As vegetation stabilizes the dunes, fore dunes and yellow dunes develop. Within dune profiles there is clear crest and trough pattern. The troughs are called slacks and result form a positive feedback of continued removal of sediment out of the trough with its transfer by wind up the windward side of the next dune. It is common for the slack to be eroded so much that it reaches the water table where salt rich ponds are found. Biodiversity increases inland as more and more plants colonise the dune system. The climax community is the typical climax community of the climate. In the UK this is Oak, Beach and Birch tree varieties.
Homework:
- Complete any outstanding work from this section.
- Complete Activity 9 on page 76 of the textbook.
- Complete the Check Your Understanding questions on page 78 of the textbook.
- Finish everything for homework and share your google docs with me.