How does the glacial system shape upland landscapes through erosion, deposition and periglacial processes?
The glaciated landscape as a system governed by mass balance; glacial, fluvioglacial and periglacial processes; the erosional and depositional landforms they create; the distribution of past and present ice; and the value, threats and management of cold environments.
An OCR A-Level Geography answer to the Glaciated landscapes option, covering the glacial system and mass balance, glacial, fluvioglacial and periglacial processes, erosional landforms (corries, aretes, troughs) and depositional landforms (moraines, drumlins, eskers), and the value, threats and sustainable management of cold environments.
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What this dot point is asking
OCR wants you to treat a glaciated upland as a system governed by mass balance, explain glacial, fluvioglacial and periglacial processes, link them to erosional and depositional landforms, describe the distribution of past and present ice, and evaluate the value, threats and sustainable management of fragile cold environments.
The answer
The glacial system and mass balance
A positive net balance means the glacier gains mass and its snout advances; a negative balance means it loses mass and retreats, though it always continues to flow downhill under gravity. Glaciers move by internal deformation (creep within the ice), basal sliding (lubricated by meltwater, faster in warm-based glaciers) and subglacial bed deformation. The thermal regime matters: warm-based (temperate) glaciers slide and erode vigorously, while cold-based (polar) glaciers are frozen to their beds and move and erode slowly. This makes the budget and thermal regime the master controls on how much work the ice does.
Glacial, fluvioglacial and periglacial processes
Glacial erosion works by plucking (meltwater freezes onto rock, which is then pulled away as the ice moves) and abrasion (embedded debris scours the bed, producing striations and rock flour). Transport carries supraglacial, englacial and subglacial debris, and deposition drops unsorted, angular till directly from the ice. Fluvioglacial processes involve meltwater, which sorts and rounds sediment and deposits it as stratified outwash. Periglacial processes operate in cold, often permafrost-affected ground beyond the ice: freeze-thaw weathering, frost heave, solifluction (downslope flow of saturated active-layer material) and ground ice growth.
Landforms of erosion and deposition
Erosional landforms include corries (armchair hollows cut by rotational ice flow), aretes (knife-edge ridges between two corries), pyramidal peaks (where three or more corries meet), glacial troughs (U-shaped valleys), hanging valleys, truncated spurs and roche moutonnees (asymmetric bedrock bumps, smoothed by abrasion updrift and plucked downdrift). Glacial depositional landforms include moraines (lateral, medial, terminal and recessional ridges of till) and drumlins (streamlined till mounds whose long axis records ice-flow direction). Fluvioglacial landforms include outwash plains (sandurs), eskers (sinuous ridges of sorted sediment from subglacial streams) and kames. Periglacial landforms include ice wedges, patterned ground, blockfields and pingos.
Distribution, value, threats and management
Ice covered roughly a third of the land surface at the last glacial maximum; today present ice is concentrated in Antarctica, Greenland, high latitudes and high mountains, while relict periglacial and glacial landscapes survive in mid-latitude uplands such as Snowdonia and the Lake District. Cold environments are valued for water storage, biodiversity, scientific records, tourism and indigenous livelihoods, but threatened by tourism pressure, resource extraction and, above all, climate change, which is driving rapid glacier retreat and permafrost thaw. Sustainable management seeks to balance economic use against conservation, through protected areas, regulated tourism and international agreements.
Examples in context
Example 1. Snowdonia (Eryri), North Wales. Snowdonia is a classic relict glaciated upland. Cwm Idwal is a textbook corrie with a rock lip and tarn, flanked by aretes, and the surrounding pyramidal summits and U-shaped troughs record vigorous Pleistocene ice. Below, hummocky and terminal moraines mark stillstands of the retreating ice, while frost-shattered blockfields and solifluction lobes on the higher slopes are periglacial features formed during and after deglaciation. The area is a National Nature Reserve and a magnet for tourism, illustrating the value-versus-threat tension central to the management strand.
Example 2. Alpine glacier retreat (the Rhone and Aletsch glaciers, Switzerland). Alpine glaciers have lost substantial length and volume since the end of the Little Ice Age, with retreat accelerating since the 1980s as mass balances have turned persistently negative under warming. The Rhone Glacier has retreated well over a kilometre and is now partly covered with insulating sheets to slow melt for tourism, while the Great Aletsch Glacier, the Alps' largest, is thinning rapidly. These show climate change as the dominant present-day threat to cold environments and provide quantified evidence for the management and synoptic links to the climate-change debate.
Try this
Q1. Name three erosional landforms produced by glaciers. [3 marks]
- Cue. Any three of: corrie, arete, pyramidal peak, glacial trough, hanging valley, truncated spur, roche moutonnee.
Q2. Explain why fluvioglacial deposits are sorted while till is not. [4 marks]
- Cue. Meltwater can only carry particles up to a size set by its energy and drops them in order as it slows, sorting and rounding them; ice carries all sizes together and dumps them en masse, leaving an unsorted, angular deposit.
Exam-style practice questions
Practice questions written in the style of OCR exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
OCR H481/01 (style)6 marksExplain how the mass balance of a glacier controls whether it advances or retreats.Show worked answer →
A medium-tariff Levels-of-Response question (AO1 and AO2). Define mass balance as the difference between accumulation (inputs of snow, avalanche and refrozen meltwater, concentrated in the upper zone of accumulation) and ablation (outputs by melting, sublimation and calving, concentrated in the lower zone of ablation), separated by the equilibrium line. A positive net balance (accumulation exceeds ablation) means the glacier gains mass and its snout advances; a negative balance means it loses mass and retreats.
For AO2, link the budget to climate: cooler or snowier conditions raise accumulation and advance the ice, while warming raises ablation and retreats it. The strongest answers note that response is lagged, the snout reacts years after the climate signal, and that even a retreating glacier still flows downhill, transporting and depositing sediment as it goes. Reward correct systems language applied to the budget rather than a generic definition.
OCR H481/01 (style)16 marksEvaluate the view that glacial processes are more important than periglacial and fluvioglacial processes in shaping glaciated landscapes.Show worked answer →
A 16-mark extended response across four Levels (AO1 and AO2). Glacial processes, erosion by plucking and abrasion and deposition of unsorted till, carve the headline landforms (corries, aretes, pyramidal peaks, glacial troughs) and dump moraines and drumlins, so they clearly dominate the large-scale relief. Fluvioglacial processes (meltwater erosion and the deposition of sorted, stratified outwash, eskers and kames) and periglacial processes (freeze-thaw, frost heave, solifluction and permafrost features such as ice wedges and patterned ground) refine and sometimes overprint that relief.
A strong AO2 judgement argues the answer is scale- and time-dependent: glacial erosion sets the macro-relief of an upland, but periglacial and fluvioglacial processes dominate during deglaciation and in the present interglacial, reworking slopes and valley floors. Reward a supported conclusion, ideally that the processes operate in sequence over a glacial cycle, rather than a flat ranking.
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Sources & how we know this
- OCR A-Level Geography (H481) specification — OCR (2016)