glacial

Glacial refers to anything pertaining to glaciers, large and long-lived masses of ice that form from snow that survives year to year and gradually deforms under its own weight. Glaciers flow slowly, deforming rock and sculpting terrain through processes of erosion and deposition. The study of glacial processes falls within physical geography and geology, and the term glaciation denotes the cycle of glacier advance and retreat driven by climate.

During the Pleistocene, cycles of glaciation expanded and contracted ice sheets across large parts of North America, Europe, and Asia. The most recent glacial maximum occurred roughly 26,000–20,000 years ago, after which climates warmed and glaciers receded, leaving behind a landscape rich in glacial landforms.

Glacial landforms include U-shaped valleys, cirques, aretes, horns, moraines (terminal, lateral, ground), drumlins, eskers, kettles, and outwash plains; coastal fjords are common at former glacier fronts. Striations and polished rock surfaces record directional movement of ice.

Today, glaciers persist in high mountains and polar regions, but many are thinning and retreating in response to climate change. Glacial meltwater supports streams and groundwater, while rising sea levels reflect the cumulative loss of land ice. In scientific and cultural contexts, glaciation serves as a key proxy for past and present climate conditions.