ee.2.2 Periglacial landscapes
Content
- Geographic inquiry and concept(s)
- How physical processes create unique landscapes in extreme environments
- Geographic knowledge and understanding
- Periglacial processes of freeze-thaw, solifluction and frost heave, and periglacial landscape features, including permafrost, thermokarst, patterned ground and pingos
- Case study or detailed examples
- Neither required by the syllabus
- Aims of this lesson
- To be able to describe the periglacial processes of freeze-thaw, solifluction and frost heave.
- To be able to explain how glacial processes contribute to the creation of periglacial landform features, including permafrost, thermokarst, patterned ground and pingos.
Base knowledge and understanding
News article
The ground is swallowing homes in this Native village in Alaska. Residents have no choice but to move
The climate crisis is causing the permafrost to melt in Alaska, forcing the village of Nunapitchuk to relocate
The Guardian · 3 November 2025
Key terms
- Freeze-thaw
- A mechanical weathering process caused by the alternative or repeated cycles of freezing and thawing of water in pores, cracks and other openings. The expansion of water upon freezing (approximately 9% by volume) forces materials apart.
- Frost heave
- The upfreezing of objects usually associated with the active layer. The predominantly upward movement of material during freezing caused by the migration of water to the freezing plane and its subsequent expansion upon freezing.
- Patterned ground
- The distinct and often symmetrical natural pattern of geometric shapes formed by the deformation of ground material due to intense frost action in periglacial regions.
- Permafrost
- Soil and rock where temperatures below 0°C persist over at least two consecutive winters and the intervening summer.
- Pingos
- Ice-cored hills formed when water moves to the freezing plane under hydraulic or hydrostatic pressure.
- Solifluction
- An agent of transport that can produce tongue-shaped lobes. The slow (0.5 to 5 cm a year) gravitational downslope movement of water-saturated, seasonally thawed materials. During the summer, the soil above the permafrost melts, but the water is unable to drain through the soil that is still frozen underneath.
- Thermokarst
- A landscape dominated by features resulting from the thawing of ground ice.
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Review
- Outline one characteristic of permafrost. [2]
- Explain how the process of freeze-thaw weathering operates in periglacial environments. [2]
- Explain two ways in which periglacial processes create distinctive landscape features. [4]
- Examine the role of freeze-thaw weathering and solifluction in shaping periglacial landscapes. [10]
- Examine how periglacial processes create distinctive landscape features in cold environments. [10]