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