1-C Glacial Landscapes Flashcards
What were glaciers like in the UK in the last ice age?
- They covered most of the UK.
- In places, it was 3 km thick.
- 10,000 years ago, as the ice melted, it produced steep peaks and sharp ridges.
Describe freeze-thaw weathering
- Water in cracks of rock surface
- Water freezes at temperature falls at night
- Water expands (10%), which cracks the rock / causes more cracks
- Ice melts and freezes again. Process cycles.
- Over time, large pieces of rock can be shattered
What are the two main processes of ice erosion?
Plucking and Abrasion
What is plucking?
Water freeze in the cracks of the rocks. Due to meltwater from above and due to pressure melting. Water freezes and as the ice moves, it plucks the rocks.
What is abrasion?
Rocks and boulders embedded in the base of the glacier cause erosion. Large boulders can cause striations
How can a glacier move and transport material?
By rotational slip and bulldozing
What is bulldozing?
When the snout of the glacier pushes material with it
What is rotational slip?
When the ice moves around a point on the base of a corrie. Imagine like a child on a swing.
What is glacial outwash?
Meltwater of the glacier can create streams. These streams can carry large amounts of sediment - glacial outwash. They are rounded and reduced in size due to attrition.
What is glacial till?
Till is sediment transported by ice and deposited beneath, at the side or at the toe of the glacier. Glacial till tends to be unsorted as the glaciers carry all shapes of rocks.
What is a corrie and how do they form?
A corrie is a deep hollow found on the flank of a mountainside. This is where glaciers begin.
As snow forms and compresses to ice, freeze-that weathering occurs. Plucked material is embedded in the base of the ice and abrasion occurs. This makes a hollow steep.
What is an arête?
When two corries develop side by side or back to back, an arête appears
What is a pyramidal peak?
When three or more corries develop side by side, a pyramidal peak appears
How are glacial troughs or U-shaped valleys created?
Before glaciation, a river valley is V-shaped. However, during glaciation, the rock in the valley sides is torn away (plucking and abrasion), which results in a glacial trough.
What are the characteristics of a glacial trough?
They are very steep, almost vertical sides lead down to a straight and wide valley floor
What is a hanging valley and how are they formed?
Tributaries used to flow down the river valley sides. However, glaciers caused these sides to be cliff-like and waterfalls are formed. The remaining portion of the original tributary valley is called a hanging valley.
What are truncated spurs and how are they formed?
Previously, the river meanders around spurs of land. However, ice has the power to remove any obstacles in its path. Truncated spurs are found along the sides of a glacial trough - the cliff-like walls on the side of the valley.
How are depositional landforms created?
They are produced when a glacier loses the ability to carry material
What are moraines?
Moraines are accumulations of rock debris that have distinct shapes.
What are the four types of moraine and give a brief description of each one.
Lateral Moraine - on the side of the valley and the glacier, which is caused by freeze-that weathering of the valley
Medial Moraine - where two glacial tributaries meet, two lateral moraines form to become a medial moraine. They run down the middle of the new glacier
Ground Moraine - material that has been lodged and deposited underneath the glacier.
Terminal Moraine - enormous ridge of material that gets bulldozed by the snout. Using this, we can work out how far a glacier has travelled to
What are drumlins and how are they formed?
Drumlins are egg-shaped hills composed of mounds of till.
They are formed by:
- material is deposited underneath a glacier as ground moraine
- movement of glaciers sculpt the ground moraine
What do drumlins show?
The direction of the movement of the glacier.
Where the glacier started - the type of rock the drumlin is made of
What is an erratic and what does it show us?
A large boulder that stands out in the landscape - composed of rock that is nowhere else to be seen.
They show us the path of ice movement
What landforms of ice erosions can be seen in the Lake District?
There are 214 significant peaks
Testaments to erosion that occurred there:
- A corrie lake called Red tarn
- An arête called Striding Edge
- Keswick town is situated on the floor of a glacial trough
Testaments to deposition that occurred there:
- Swarms of drumlins in Swindale in the northeast Lake District
- Clear signs of glacial erratics shows that the glacier came from Scotland