AO1 – (8 marks)

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Markers must apply the descriptors in line with the general marking guidance and the qualities outlined in the levels-based mark scheme below.

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AO1

The distinctiveness can be associated with the form, position and the deposits forming the feature as well as ice the distinction between ice contact and pro glacial features.
Eskers are linear features that often show a close correspondence with the recent direction of ice movement. Eskers are often formed within ice-walled tunnels by meltwater reworking sediment (often coarse- grained, water-laid sand and gravel) that was found at the base of the glacier. Eskers often form at the time of the glacial maximum when glacier movement is slow. Once the retaining ice walls have melted away, these meltwater reworked debris are deposited as distinctive long winding ridges such as those found in Rothiemurchus. They are also distinctive to glacial deposits as they are stratified and sorted and often have distinct bedding of the sediments.
Kames are irregularly shaped hills consisting of sand, gravel and till. They are associated with a retreating glacier when material resting on the glacier is reworked by meltwater. Kames form in zones of melting ice such as crevasses, moulins and larger cavities. As the ice melts, the kame begins to emerge as a low hill such as those found in Gleann Einich. Bedded and sorted sand and gravel predominates but often sharp lateral variations are apparent in the calibre of the material, indicating rapid changes in flow velocity. They are distinctive as they have an irregular pattern as compared to drumlins which often occur in swarms.
Kame terraces are also thought to be landforms formed that are parallel to the ice flow. Kame terraces form when sediment accumulates in ponds and lakes trapped between lobes of glacier ice or between a glacier and the valley side. As the glacier retreats they are deposited on the valley sides. Typically, the sediment comprises well-bedded and sorted sand and gravel. They are distinctive as they can form steps leading down to the valley floor.
Kettle holes are formed by blocks of ice that are separated from the main glacier. The isolated blocks of ice then become partially or wholly buried in glacial meltwater outwash material. When the ice blocks eventually melt they leave behind holes or depressions that fill with water to become kettle holes such as Lochan Deo.
Pro glacial lakes are ephemeral lakes created where glacier ice blocks a valley or embayment and ponds the glacial meltwater. The lakes may drain through the ice barrier or via spillways through cols. Drainage of these lakes may form sculpted bedrock surfaces and leave behind poorly-sorted boulder gravels.
Sandurs are found in glaciated areas, such as Svalbard, Kerguelen Islands, and Iceland. Glaciers and icecaps contain large amounts of silt and sediment, picked up as they erode the underlying rocks when they move slowly downhill, and at the snout of the glacier, meltwater can carry this sediment away from the glacier and deposit it on a broad plain. The material in the outwash plain is often size- sorted by the water runoff of the melting glacier with the finest materials, like silt, being the most distantly re-deposited, whereas larger boulders are the closest to the original terminus of the glacier.
Meltwater channels – also known as glacial overflow channels – are the product of erosion. Glacial meltwater flowing away from the glacier front is often heavily charged with debris and moving at high velocities. Like normal rivers but with high and fluctuating discharges, these proglacial channels are capable of rapid deepening of channels, even in bedrock. Large amounts of meltwater have much energy to erode and carve out deep gorges that today are occupied by streams too small to have created the valleys they flow in. These also form as the original course followed by a river before glaciation may be blocked by ice or as an overflow from a proglacial lake (one that results from meltwater from glaciers).Examples include Newtondale and Lake Pickering, Lake Lapworth and Ironbridge Gorge. Accept other explanations of how glacial meltwater can contribute to the formation of recognised fluvio-glacial features.

Glacial Landforms & Landscapes (Edexcel A Level Geography)

Topic Questions