AQA · A-Level · Geography
Course version: 7037 · Version from Sept 2018
Periglacial features and processes: permafrost, active layer and mass…
Full specification wording
Systems and processes: Periglacial features and processes: permafrost, active layer and mass movement.
Periglacial environments are characterised by intense frost action and permafrost, occurring at the margins of glacial ice or in high-latitude regions.
Checked against the AQA 7037 specification (opens in a new tab) on .
- Point 6 of 6
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Periglacial environments are characterised by intense frost action and permafrost, occurring at the margins of glacial ice or in high-latitude regions. Permafrost is ground that remains continuously at or below 0 °C for at least two consecutive years. Above this lies the active layer, which thaws during the brief summer and freezes in winter. This seasonal thawing saturates the active layer because the underlying permafrost is impermeable, leading to distinct mass movement processes. Solifluction is a key mass movement where the waterlogged active layer slowly flows downslope under gravity, creating features like solifluction lobes. Frost creep also contributes to mass movement through the cyclical heaving and settling of soil particles.
What earns the marks
- Define permafrost accurately as ground remaining at or below 0 °C for two or more consecutive years.
- Explain the role of the active layer and its seasonal freeze-thaw cycle.
- Describe how the impermeable nature of permafrost leads to the saturation of the active layer during the summer thaw.
- Explain solifluction as the downslope flow of saturated soil under the influence of gravity.
- Identify and describe resulting periglacial features such as solifluction lobes or terracettes.
Common mistakes and how to put them right
Defining permafrost as permanently frozen water.
Put it right: Define permafrost as ground (soil or rock) that remains at or below 0 °C for at least two consecutive years, regardless of its water content.
Confusing solifluction with standard soil creep.
Put it right: Specify that solifluction requires a saturated active layer overlying an impermeable permafrost boundary, whereas soil creep occurs in non-periglacial environments.
Stating the active layer is permanently frozen.
Put it right: Explain that the active layer is the top layer of soil that thaws in the summer and freezes in the winter.
Exam tips
- Always include the specific timeframe of at least two consecutive years when defining permafrost to secure full marks.
- Use annotated diagrams to show the relationship between the active layer, the permafrost table, and solifluction lobes on a slope.
- Link the seasonal temperature changes directly to the saturation of the active layer to explain why mass movement occurs.
Try the lesson
The start of the Systems and processes: Periglacial features and processes: permafrost, active layer and mass movement. lesson, made from checked teaching notes for this specification point.
Have a go first
What defines the active layer in a periglacial environment?
Listen
Periglacial environments are characterised by intense frost action and permafrost, occurring at the margins of glacial ice or in high-latitude regions. Permafrost is ground that remains continuously at or below 0 °C for at least two consecutive years. Above this lies the active layer, which thaws during the brief summer and freezes in winter. This seasonal thawing saturates the active layer because the underlying permafrost is impermeable, leading to distinct mass movement processes. Solifluction is a key mass movement where the waterlogged active layer slowly flows downslope under gravity, creating features like solifluction lobes. Frost creep also contributes to mass movement through the cyclical heaving and settling of soil particles. A strong answer earns marks for these points. Define permafrost accurately as ground remaining at or below 0 °C for two or more consecutive years. Explain the role of the active layer and its seasonal freeze-thaw cycle. Describe how the impermeable nature of permafrost leads to the saturation of the active layer during the summer thaw. Explain solifluction as the downslope flow of saturated soil under the influence of gravity. A common slip: Defining permafrost as permanently frozen water. Instead, Define permafrost as ground (soil or rock) that remains at or below 0 °C for at least two consecutive years, regardless of its water content. Exam tip: Always include the specific timeframe of at least two consecutive years when defining permafrost to secure full marks.
Key words
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Permafrost
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Active layer
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Solifluction
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Frost creep
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See every definition
- Permafrost
- Ground that remains continuously at or below 0 °C for at least two consecutive years.
- Active layer
- The layer above the permafrost which thaws during the brief summer and freezes in winter.
- Solifluction
- A key mass movement where the waterlogged active layer slowly flows downslope under gravity, creating features like solifluction lobes.
- Frost creep
- A process that contributes to mass movement through the cyclical heaving and settling of soil particles.
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