Mearns Castle High School. Geography Department. Glaciated Landscapes

Transcription

1 Mearns Castle High School Geography Department Glaciated Landscapes

2 Lesson One: Location of Glaciated Uplands in the British Isles The Ice Age in Britain began about 1,000,000 years ago and lasted until about 20,000 years ago km Ice Age in Britain During this time temperatures fluctuated and ice advanced and retreated four times. The northern and eastern parts of the British Isles were covered in ice.

3 Exercise one Complete your own copy of the map of the British Isles labelling the Main regions highlighted on you map H:\ACTIVstudio 2\My Flipcharts\Glaciated landscapes.flp

4 What is the glacier system? The glacier system consists of inputs, transfers (flows), stores and outputs in the same way as a river. Inputs come from avalanches along the sides of the glacier but mainly from precipitation as snow. Over time snow accumulates and is compressed into ice. The water held in storage is the glacier. Under the force of gravity, the glacier flows downhill. Meltwater is the main output from the glacier, along with some evaporation.

5 Processes of Erosion Abrasion The moraine frozen into the glacier scours the valley sides and base. This is a sandpapering effect, similar to corrasion by a river but on a far larger scale. Plucking The water at the bottom of the glacier freezes onto rock on the valley base. As the glacier moves, the rock is pulled away from the valley base. Plucking mainly occurs when the rock is well-jointed.

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7 Landforms created by glacial erosion The landforms created by glacial erosion are: Corries Pyramidal peaks Glacial troughs (U-shaped valley) Hanging valleys Truncated spurs Arêtes

8 How is a corrie formed? Snow collects in a natural hollow on the side of a mountain. Over time, further snow collects in the hollow. This extra weight compresses the snow underneath, turning it into ice. rock lip The hollow is deepened and widened by the corrie glacier through the processes of abrasion and plucking. This overdeepening leads to an armchair shape characteristic of a corrie and causes a rock lip to be formed.

9 Corrie formation

10 Diagram of a corrie

11 Explain the formation of a corrie

12 Example of a corrie: Cwm Idwal steep backwall tarn bowl-shaped corrie

13 Formation Of an Arete Corrie Corrie Corrie Corrie

14 Video The Carn Mòr Dearg Arête, a popular route of ascent to Ben Nevis

15 Formation of a pyramidal peak arête Pyramidal peaks are formed when three or more corries cut backwards into the same mountain. tarn corrie

16 Label the pyramidal peak diagram

17 U Shaped Valley How and why do these valleys differ? river valley glaciated valley Unlike a river, a glacier fills the entire valley and so has much more power to erode. It does not have to wind around interlocking spurs and can widen, deepen and straighten its valley.

18 Characteristics of a U shaped valley What are the characteristics of a U shaped Valley steep valley sides Between truncated spurs are hanging valleys which have not been eroded as deeply as the main valley. Interlocking spurs are truncated as the glacier cuts straight through the landscape. hanging valley truncated spurs misfit stream wide and flat valley floor The river that flows through the valley after the ice age is described as a misfit stream.

19 How a U-shaped valley is formed. Before glaciation During glaciation After glaciation Valley is V- shaped Vertical/downward erosion V-shaped valley is filled with ice Moving ice erodes the sides and bottom of the valley through abrasion, plucking and bulldozing Valley becomes U-shaped - (a glacial trough) with Very steep sides and Misfit stream A wide and flat bottom

20 Hanging Valley Tributary valley is left hanging over the main valley - hanging valley What feature is this? A truncated spur Main valley eroded faster and deeper than the

21 Misfit Stream and Ribbon Lochs There is no way that this river could have eroded this wide valley

22 This Loch takes up the whole valley floor Loch Lomond