Higher Lithosphere - Glaciation 

The overall name for glacial deposits is DRIFT. Sediments that are directly deposited by the ice are called TILL.&nbsp; Sediments that are deposited by the vast quantities of melt water are called FLUVIO GLACIAL deposits.

LITHOSPHERE GLACIATION Higher Geography

Moraine is the material eroded by the glacier as it moves downslope. It is angular in shape due to freeze thaw and plucking. Till deposits are poorly sorted. They are all different sizes and rock types mixed together. Fluvial deposits are sorted. They have been moved by melt water and sorted by weight with the lightest moraine moved furthest.&nbsp;

Formation of erosional and depositional features in glaciated landscapes: 1. Corrie 2. Arête 3. Pyramidal peak 4. U-shaped valley 5. Hanging valley 6. Ribbon lake 7. Drumlin&nbsp; 8. Esker&nbsp; 9. Terminal moraine&nbsp;

Eskers are moulds of sand and gravel (1) that meander across the landscape (1). Because they are fluvioglacial the moraine is sorted by weight (1). They are fossilised courses of sub glacial melt water (1).&nbsp;They are formed within the glacier (1). Subglacial esker (forming at the bottom of the glacier) – so the deposits will be undisturbed (1).

LITHOSPHERE: GLACIATION 2

Explain the conditions and processes involved in the formation of a U-shaped valley. You may wish to use an annotated diagram or diagrams. 10

Rotational sliding over deepens the central part of the corrie (1) When two corrie form back to back a narrow ridge is formed in-between (1) Further frost shattering will make the ridge narrower and scree slopes may form (1) An example of this is Striding Edge in the Lake District (1)

<a href="https://timeforgeography.co.uk/videos_list/glaciation/Aretes/">https://timeforgeography.co.uk/videos_list/glaciation/Aretes/</a> 1.28 minutes

<a href="https://timeforgeography.co.uk/videos_list/glaciation/formation-drumlins/">https://timeforgeography.co.uk/videos_list/glaciation/formation-drumlins/</a> 7.23 minutes

Description Drumlins are elongated hills of glacial deposits (1), formed when the glacier is still moving (1). The steep ‘sloss’ slope faces uphill and the gentle ‘lee’ side downhill (1), which shows the direction of travel (1). Explanation When the glacier losses power (due to temperature increase) (1) and becomes overloaded with sediment it deposits the unsorted moraine (1). This can also be caused by a small obstacle (1) or outcrop of rock which can act as a trigger point for further moraine to be deposited (1). The Drumlin is then moulded by the glacier&nbsp;although not significantly as it has lost power due to melting (1). Several often occur together in groups called swarms (1).

1 – Plucking: when ice freezes onto bedrock and rips this out (1) making the valley / corrie steeper (1).

2 – Abrasion: when angular rock embedded in the glacier grinds the bedrock (1) making it deeper (1).

3 - Freeze – Thaw: water in rock cracks expands when it freezes (1), repeated expansion weakens and breaks the rock (1).

LITHOSPHERE: GLACIATION 3

Explain the formation of a Terminal Moraine. You may wish to use an annotated diagram or diagrams. 6

Description Moraine is the material transported and deposited by the glacier as it moves downslope (1). Forming a low ridge across the valley floor (1) It is angular in shape due to freeze thaw and plucking (1). Terminal moraine is found in front of the snout of the glacier (1) and marks the furthest point it reaches (1). Explanation When a glacier reaches lower altitudes, or if the temperatures increases, the ice melts and deposits moraine (1) at its snout. Because the glacier is so powerful moraine deposits are poorly sorted (1), they are all different sizes and rock types are mixed together (1).

<a href="https://timeforgeography.co.uk/videos_list/glaciation/glacial-deposits-types-moraine/">https://timeforgeography.co.uk/videos_list/glaciation/glacial-deposits-types-moraine/</a> 8.45 minutes

2. I can explain how a glacier erodes and shapes the landscape by the processes of: 1.Plucking 2.Abrasion 3.Freeze - Thaw

Smaller tributary glaciers have less powerful (1) glaciers which do not erode as deeply (1).&nbsp; These smaller valleys are left “hanging” over the main u-shaped valley floor (1). Often leads to a waterfall forming (1) (although a different process to one formed by rivers) Interlocking spurs are truncated by the power of the glacier (1), leaving crags or exposed rock faces at the sides of the valley (1). An example of a Hanging Valley is Little Langdale (1).

Following the existing v shaped river valleys (1) Former interlocking spurs may be cut off by glacier (1) leaving crags or exposed rock faces at the sides of the valley (1). Resulting in steep/crags truncated spurs(1). Over time the valley becomes straightened widened and deepened(1). After glaciation the previous river may return called a misfit stream(1). The valley sides are steep and the floor is flat and wide (1). An example is Great Langdale Valley in the Lake District (1).

<a href="https://timeforgeography.co.uk/videos_list/glaciation/formation-of-U-shaped-valleys/">https://timeforgeography.co.uk/videos_list/glaciation/formation-of-U-shaped-valleys/</a> 4.17 minutes&nbsp;

Rotational sliding over deepens the central part of the hollow (1) When three or more corrie erode back to back it forms a pyramidal peak (1) Further frost shattering will make the peak more pointed and scree slopes may form (1) An example of this is Helvellyn in the Lake District (1)

<a href="https://timeforgeography.co.uk/videos_list/glaciation/Pyramid-peaks/">https://timeforgeography.co.uk/videos_list/glaciation/Pyramid-peaks/</a> 1.15 minutes

Glacial Deposition Features

You must be able to explain the formation of the following features: Till Features 1. Terminal Moraine 2. Drumlin Fluvial Features 3. Esker

Rotational sliding over deepens the central part of the hollow (1) Friction causes ice to slow at the front edge allowing a rock lip to form (1) Once the glacier has melted this hollow can fill with water to form a Corrie Loch or Tarn (1) An example of this is Red Tarn in the Lake District (1)

<a href="https://timeforgeography.co.uk/videos_list/glaciation/corries/">https://timeforgeography.co.uk/videos_list/glaciation/corries/</a> 1.54 minutes&nbsp;

Following the existing v shaped river valleys(1). Former interlocking spurs may be cut off by glacier(1), resulting in steep/crags truncated spurs(1). Over time the valley becomes straightened widened and deepened(1). Ribbon lakes form where softer bedrock is eroded more deeply than the surrounding area (1). Or can form where a terminal or recessional moraine creates a dam(1). An example is Lake Windermere (1).

1. I can explain how a glacier is formed: Form in a North facing hollow as more shade (1) When more snow falls in winter than melts in the summer (1) Snow compresses to form neve and then glacial ice (1) Moves downhill due to its own weight and gravity (1)

Can you watch the following sections: Neve formation 5:37 – 7:54 minutes&nbsp;

<a href="https://www.twigscotland.com/film/glaciers-1096/">https://www.twigscotland.com/film/glaciers-1096/</a> 2.39 minutes

LITHOSPHERE: GLACIATION 1

Explain the conditions and processes involved in the formation of a corrie. You may wish to use an annotated diagram or diagrams. 8

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