The shaping of relief
A cliff, a river canyon, a dune or a U-shaped valley all tell the same story: over thousands of years, water, wind or ice have been wearing away, carrying off and depositing materials until they have shaped the landscape you see today.
The stages of relief shaping
If you walk along a mountain summit, you will see large blocks of sharp-edged rock split apart beside the cliff walls, while at a river mouth you find only fine grains of rounded sand: how does solid rock change and travel from the mountain to the sea?
What is weathering? Give an example related to the action of frost on rocks (freeze-thaw weathering).
What is weathering? Give an example related to the action of frost on rocks (freeze-thaw weathering).
Order the stages of landscape shaping — deposition, erosion, weathering, and transport — and define each with a single sentence.
Order the stages of landscape shaping — deposition, erosion, weathering, and transport — and define each with a single sentence.
State whether each of these processes is weathering, erosion, or deposition: a rock cracks due to the action of ice; a river wears away its channel; the wind deposits…
State whether each of these processes is weathering, erosion, or deposition: a rock cracks due to the action of ice; a river wears away its channel; the wind deposits sand and forms a dune.
The agents of relief shaping
Match each agent with the landform it produces: a river, wind, a glacier, and the sea, with dunes, a river valley, a cliff, and a glacial corrie.
Match each agent with the landform it produces: a river, wind, a glacier, and the sea, with dunes, a river valley, a cliff, and a glacial corrie.
Match each landform with the agent that shapes it: a sea stack, a river canyon, a dune field, and a moraine, with the sea, a river, the wind, and a glacier.
Match each landform with the agent that shapes it: a sea stack, a river canyon, a dune field, and a moraine, with the sea, a river, the wind, and a glacier.
The biosphere also shapes landforms. Explain two examples: the action of tree roots on rocks and the building of reefs by corals.
The biosphere also shapes landforms. Explain two examples: the action of tree roots on rocks and the building of reefs by corals.
The river, from mountain to sea
Near its source, the river is a fast torrent that smashes boulders along its bed, but in its final stretch it flows slowly, wide and muddy over a bed of silt: why do the behaviour and force of the water change so much along its course?
Explain the difference between erosion and transport using the work of a river as an example.
Explain the difference between erosion and transport using the work of a river as an example.
The diagram shows a river from its source in the mountains to its mouth at the sea. State in which of the labelled zones (A, B, or C) erosion, transport, and deposition…
The diagram shows a river from its source in the mountains to its mouth at the sea. State in which of the labelled zones (A, B, or C) erosion, transport, and deposition predominate, and justify your answers.
In the upper course of a mountain river, erosion predominates, whereas at its mouth, deposition predominates. Relate this change to the gradient and the speed of the…
In the upper course of a mountain river, erosion predominates, whereas at its mouth, deposition predominates. Relate this change to the gradient and the speed of the water.
The shaping of the coast
What is deposition? Give an example of a place where a river deposits the materials it transports.
What is deposition? Give an example of a place where a river deposits the materials it transports.
Name two coastal landforms produced by the action of the sea and briefly explain how one of them forms.
Name two coastal landforms produced by the action of the sea and briefly explain how one of them forms.
On a rocky coast, isolated sea stacks, rock arches, and cracks in the cliff walls can be seen. Order the stages this shaping goes through and cite the agent responsible.
On a rocky coast, isolated sea stacks, rock arches, and cracks in the cliff walls can be seen. Order the stages this shaping goes through and cite the agent responsible.
Relief and human action
A hundred kilometres from the coast, a new hydroelectric dam is built on a river and, a decade later, the residents of the beaches at the river mouth watch the sea swallow up the coastline: how can a dam in the mountains make a beach shrink by the sea?
A construction company excavates the base of a clay slope with an inclination of 35° to widen a road. A geological report warns that, after heavy rains, there is a very…
A construction company excavates the base of a clay slope with an inclination of 35° to widen a road. A geological report warns that, after heavy rains, there is a very high risk of mass wasting onto the road. The construction company claims that planting a superficial layer of grass will be enough to hold the ground.
- a) Refute the construction company's claim: justify what happens to clay when it becomes saturated with water and why the shallow roots of grass will not prevent a deep-seated slope failure.
- b) Design and describe two different structural geotechnical measures (such as retaining walls with drainage, deep anchors, or slope reduction through benching/terracing) to stabilize the slope, justifying the physical principle by which each would prevent collapse.
Before the construction of a dam, a river contributed $120\,000\ \text{t}/\text{year}$ of sediment to its delta. After the dam was built, the input was reduced to…
Before the construction of a dam, a river contributed $120\,000\ \text{t}/\text{year}$ of sediment to its delta. After the dam was built, the input was reduced to $30\,000\ \text{t}/\text{year}$. At the same time, coastal marine dynamics (waves and longshore currents) remove $75\,000\ \text{t}$ of sand each year from the delta's coast.
- a) Calculate the net annual sediment balance of the deltaic coast (sediments supplied minus sediments removed) before and after the dam was built.
- b) Based on the result, predict what will happen in the medium term to the coastline and the adjacent dune ecosystems.
- c) The local city council proposes dredging sand from the nearby seabed and periodically dumping it onto the beach. Critically evaluate this proposal: justify why it does not solve the root problem and what unexpected negative impact it could cause on the marine seabed.
The beaches of a coast are fed by the sand carried by the longshore current. If a port is built that interrupts this current, predict what will happen to the beaches…
The beaches of a coast are fed by the sand carried by the longshore current. If a port is built that interrupts this current, predict what will happen to the beaches located on either side of the port and justify your answer.