Landform shaping
The Grand Canyon, a sand dune on the Texas coast, and a U-shaped valley in Yosemite 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 landform shaping
If you hike along a summit in the Rocky Mountains, you will see large blocks of sharp-edged rock split apart beside the cliff walls, while at the mouth of the Mississippi River you find only fine grains of rounded sand and mud: 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.
Weathering can also be biological. Explain what it consists of and give two examples, one related to roots and one to lichens.
Weathering can also be biological. Explain what it consists of and give two examples, one related to roots and one to lichens.
The agents of landform 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 cirque.
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 cirque.
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.
A glacier drags blocks of rock along its base and deposits them as it melts, forming moraines. Explain how the same agent carries out erosion, transport, and deposition…
A glacier drags blocks of rock along its base and deposits them as it melts, forming moraines. Explain how the same agent carries out erosion, transport, and deposition at the same time.
In a mountain range, a main valley is observed with a wide floor and a U-shaped cross-section, featuring polished vertical walls and striations on the rock. However, on…
In a mountain range, a main valley is observed with a wide floor and a U-shaped cross-section, featuring polished vertical walls and striations on the rock. However, on the bedrock floor of that same valley, a present-day river has carved a narrow, deep gorge with a V-shaped profile.
- a) Interpret the geological history of this landform: deduce which two external geological agents have acted successively over time to produce this combination of shapes.
- b) Justify what interaction between the atmosphere (climate change), the hydrosphere, and the geosphere explains why the first shaping agent disappeared from the area and was replaced by the action of the second.
The river, from mountain to sea
Near its source in the Rockies, a 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 behavior 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 labeled 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 labeled 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.
Landforms and human action
Sixty miles 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 Gulf swallow up the coastline: how can a dam in the mountains make a beach shrink by the sea?
The terraces of traditional farms slow down erosion on hillsides. Explain how they act on runoff and what happens when they are abandoned.
The terraces of traditional farms slow down erosion on hillsides. Explain how they act on runoff and what happens when they are abandoned.
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.