Key Terms: Glaciated landscape development (AQA A Level Geography): Revision Note

Glacial landscapes - key terms

Ablation zone – The lower part of a glacier where melting, evaporation and sublimation exceed snowfall, resulting in net ice loss.

Accumulation zone – The upper part of a glacier where snowfall exceeds melting and other losses, leading to ice build-up.

Arête – A sharp, narrow ridge formed when two corrie glaciers erode back-to-back into a mountain.

Corrie (cwm/cirque) – A bowl-shaped hollow with a steep back wall, formed by rotational ice movement and freeze–thaw weathering.

Corrie lake (tarn) – A circular lake found within a corrie after the glacier melts, held in by a lip of moraine.

Drumlin – A smooth, elongated hill of glacial till shaped beneath a glacier, with a steep stoss side and gentle lee.

Erratic – A large boulder transported and deposited by a glacier, often resting on rock of a different type.

Glacial trough (U-shaped valley) – A deep, wide valley with steep sides and a flat floor, carved by a valley glacier.

Ground moraine - Material dragged under the base of the glacier and is deposited over a wide area.

Hanging valley – A smaller valley left above the main glacial trough, often forming waterfalls.

Lateral moraine - Materials deposited along both sides of the glacier.

Medial moraine - A ridge of deposited material in the middle where two glaciers meet and continue to flow downhill together.

Push moraine - These form if the glacier advances after retreat pushing material in front of it.

Pyramidal peak – A sharply pointed mountain summit created when three or more corrie glaciers erode towards each other.

Recessional moraine - Deposited material shows the point of glacier retreat.

Ribbon lake – A long, narrow lake occupying a glacial trough, formed in areas of softer rock eroded more deeply.

Roche moutonnée – A rock outcrop shaped by glacial erosion, smoothed on the stoss side and plucked on the lee side.

Terminal moraine - Material deposited at the snout of the glacier.

Till plain – A flat landscape created by the widespread deposition of glacial till as ice melts.

Truncated spur – A steep, cliff-like edge formed when a glacier cuts off former interlocking river spurs.

Fluvioglacial processes & landforms - key terms

Ablation – The melting or loss of glacial ice through surface melt, evaporation, or sublimation.

Attrition – The process of sediment particles colliding and breaking down into smaller, smoother fragments in meltwater streams.

Deposition – The dropping of sediment when meltwater loses energy, forming features such as kames and eskers.

Englacial channel - Meltwater streams in the body of glacial ice.

Esker – A long, sinuous ridge of sorted sand and gravel deposited by meltwater in subglacial tunnels.

Fluvioglacial – Refers to the processes and landforms created by glacial meltwater, particularly deposition and erosion.

Glacial varves – Pairs of sediment layers deposited in proglacial lakes, with coarse summer and fine winter layers indicating annual cycles.

Kame – A mound of stratified sand and gravel deposited by meltwater on or within a glacier.

Kame delta – A flat-topped landform created when meltwater streams deposit sediment into a proglacial lake.

Kame terrace – A ridge of sand and gravel deposited between a glacier and valley wall by lateral meltwater streams.

Kettle hole – A hollow formed when a detached block of glacial ice is buried by outwash and then melts.

Lateral channel - Meltwater channels that follow the glacial edge.

Meltwater – Water produced from glacial melting, capable of transporting large volumes of sediment.

Meltwater channel – A steep-sided valley or channel carved by glacial meltwater, which may be subglacial, englacial, or supraglacial.

Moulins - A rough circular, vertical shaft in a glacier which is formed by meltwater erosion.

Nivation – A process involving freeze–thaw and meltwater erosion under snow patches, leading to hollow formation.

Outwash plain – A flat expanse of sorted sand and gravel deposited by braided meltwater streams beyond the glacier snout.

Proglacial channel - Where meltwater drains from the front of the glacier.

Subglacial channel - A channel found beneath the glacier with complex braided stream systems.

Periglacial landforms - key terms

Blockfield (felsenmeer) – An area covered by angular rock fragments produced by intense freeze–thaw weathering.

Ice lens – A body of ice formed in soil where moisture accumulates and freezes, causing soil heave.

Ice wedge – A wedge-shaped body of ice formed when cracks in permafrost fill with water and freeze repeatedly.

Open-system pingo – A dome-shaped hill formed when groundwater moves through unfrozen gaps in discontinuous permafrost and freezes.

Ognip – A collapsed pingo, often forming a water-filled depression after the ice core melts.

Patterned ground – Surface features in periglacial areas, such as polygons or stripes, created by freeze–thaw sorting.

Permafrost – Ground that remains permanently frozen (at or below 0°C) for at least two consecutive years.

Pingo – A mound with a core of ice, formed in periglacial areas due to freezing groundwater.

Solifluction – The slow, downslope movement of saturated soil during the seasonal thaw of the active layer.

Solifluction lobe – A tongue-shaped accumulation of soil and debris resulting from solifluction on sloping ground.

Stone stripes – Linear arrangements of stones on sloped ground, caused by freeze–thaw sorting and movement.

Talik – Unfrozen ground within or beneath permafrost, typically insulated by overlying material or water.

Terracette – Small, step-like terraces on a hillside caused by soil movement from freeze–thaw or solifluction.

Thermokarst – An irregular surface landscape caused by the melting of ground ice, resulting in subsidence and hollows.