Glacial Landforms: Corrie and Arête Formation

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Questions and Answers

What process contributes to the formation of a U-shaped valley through the movement of a glacier?

River erosion

Erosion through abrasion (correct)

Sediment deposition

Tectonic uplift

How do freeze-thaw cycles affect the formation of a valley?

They solely contribute to sediment deposition.

They deepen the valley by widening cracks in rocks. (correct)

They prevent glacial movement.

They smooth out the valley floor.

Which characteristic best describes a drumlin?

A steep cliff formed by erosion.

A flat valley floor derived from river action.

A round mountain peak.

An elongated hill formed by glacial deposits. (correct)

What primarily causes the formation of a terminal moraine?

Glacial movement and subsequent deposition at melt sites. Signup and view all the answers

What happens to the flow of meltwater streams within a glacier that leads to the formation of esker deposits?

They lose energy and deposit materials being carried. Signup and view all the answers

Which statement is true regarding snow accumulation in valley formations?

North-facing hollows retain more snow due to shade. Signup and view all the answers

In what way does glacial abrasion modify a valley over time?

It grinds the valley floor and makes it deeper. Signup and view all the answers

How are the materials found in drumlins characterized?

Unsorted and a result of glacial deposits. Signup and view all the answers

What is a ribbon lake, and how does it typically form?

A long, narrow lake formed through glacial erosion of softer bedrock. Signup and view all the answers

What role do smaller particles play in the formation of an esker?

They can be carried farther by meltwater streams. Signup and view all the answers

Why are north-facing hollows more likely to form corries?

They are sheltered from prevailing winds, allowing snow to accumulate. Signup and view all the answers

What is the primary way in which a glacier deepens a corrie?

By the erosion of the glacier's ice crystals grinding against the bedrock. Signup and view all the answers

How does a rock lip form at the front edge of a corrie?

Friction between the glacier and the bedrock slows the ice, allowing sediment to accumulate. Signup and view all the answers

What feature is created when two corries form side by side?

An arête Signup and view all the answers

Which of the following processes is responsible for making arêtes and pyramidal peaks more jagged after the ice age?

Freeze-thaw weathering Signup and view all the answers

How does the formation of a pyramidal peak differ from the formation of an arête?

Pyramidal peaks are formed by the erosion of three or more corries, while arêtes are formed by the erosion of two corries. Signup and view all the answers

What is the role of plucking in the formation of both arêtes and pyramidal peaks?

Plucking deepens the corries, creating the sharp peaks and ridges. Signup and view all the answers

Study Notes

Corrie Formation

Snow accumulates in north-facing hollows due to increased shade, allowing prolonged snow accumulation.
Compaction and freezing transforms snow into glacial ice.
Gravity drives the movement of the glacier downhill.
Plucking occurs as ice freezes onto the bedrock and pulls away fragments, steepening the back wall.
Abrasion happens when rocks embedded in the ice grind the hollow, deepening it.
Rotational slip further deepens the hollow.
At the front, friction causes ice to slow down, forming a rock lip.
Rainwater collects behind the lip.
Melting ice leaves a characteristic armchair-shaped hollow, called a corrie.
Example: Red Tarn.

Arête Formation

Corrie formation occurs first, in tandem with the formation of a second corrie.
Plucking deepens the slopes and walls of the corrie, drawing the corries closer together.
The resulting ridge is sharp and knife-like, known as an arête.
Freeze-thaw weathering contributes to the sharpness after the ice age.
Example: Striding Edge.

Pyramidal Peak Formation

Three or more corries form around a summit.
Plucking processes create multiple arêtes, surrounding the summit.
Freeze-thaw weathering contributes to the sharpness of the peak.
Example: Mount Everest.

U-Shaped Valley Formation

Snow accumulates, solidifying into glacial ice.
Glacial ice moves downhill due to gravity.
Abrasion occurs as rocks within the ice grind the valley floor, causing it to deepen.
Freeze-thaw action also steepens the valley sides by widening cracks.
Glacial erosion transforms V-shaped valleys into wider, deeper, straighter U-shaped valleys.
A flat valley floor and steep valley sides result from melting ice.
Example: Glen Coe.

Ribbon Lake Formation

Glaciers erode valleys, deepening some sections more than others.
Glaciers can pluck and abrade rock at varying rates.
Softer bedrock is eroded deeper than the surrounding rock.
When glaciers melt, the deepened sections fill with meltwater.
Terminal moraine can also act as a natural dam.
Example: Loch Ness.

Drumlin Formation

Drumlins are elongated hills composed of unsorted glacial deposits (till, boulder clay).
The ice deposited the material at the same time.
The steep "stoss end" faces up-valley, and the gentler "lee slope" faces down-valley.
Drumlins form when sediment becomes too heavy for the glacier to carry.
As the glacier flows, it shapes the sediment into streamlined mounds.
Small obstacles can act as trigger points, causing material accumulation.
Drumlin formations can occur when ice passes over deeper sediment layers.
Increased pressure from the ice molds the sediment into drumlin shapes.
Drumlins might be reshaped by subsequent ice movements.
Drumlins are often found in clusters (swarms).

Terminal Moraine Formation

A ridge across a valley, made of unsorted glacial deposits (till, boulder clay).
Glacial movement pushes sediment in front of the glacier.
Melting glaciers deposit the moraine.
This marks the furthest extent of the glacier.
Can act as a dam, creating ribbon lakes.

Esker Formation

Winding ridges along valley floors, formed by meltwater streams.
Forms within ice-walled tunnels at the base of the glacier.
Composed of sands and gravels, carried by meltwater streams.
Streams lose power and deposit the material along the riverbed.
Larger particles are deposited first, smaller particles are carried further.
The deposits are sorted.
Stones are more rounded (attrition).
Eskers are visible when the glacier melts.

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Description

Explore the fascinating processes behind the formation of corries and arêtes. This quiz delves into how snow accumulation, glacial movement, and erosion shape these stunning features in the landscape. Test your knowledge of glacial geology and understand the impact of natural forces.