periglacial

Periglacial describes environments at the margins of glaciers and ice sheets where cold conditions and freeze-thaw processes shape the landscape. The term refers to active processes and landforms outside continuous ice cover but strongly influenced by freezing temperatures. Periglacial zones occur in high-latitude and high-altitude regions as well as in cold seasons within temperate areas.

Key processes include frost action, such as freeze-thaw cracking and frost heave; cryoturbation, which mixes soil through freezing and thawing; and gelifluction or solifluction, the downslope movement of water-saturated soil during thaw. Ice segregation and ground-ice formation create features such as ice wedges. Patterned ground, including polygons, stripes, and nets formed by differential frost-heaving, is common in periglacial terrains.

Prominent landforms include pingos (ice-cored mounds), frost wedges and ice-cored polygons, patterned-ground terraces, solifluction lobes, stone nets, and thermokarst features in ice-rich sediments when ground ice thaws. Periglacial processes produce both surface and subsurface forms, often leaving remnants long after ice retreat.

Climatic context: periglacial settings require cold winters and sufficient moisture to form ground ice; they occur during glacial cycles and in present-day high-latitude or high-altitude environments such as the Arctic, subarctic regions, and alpine zones. Human activities and climate change are affecting periglacial landscapes through thawing of permafrost and altered hydrology.

Related terms include permafrost, cryoturbation, and frost weathering.