ice lens

Ice formation refers to any mass of ice that occurs on Earth's continents or surface waters, forming wherever liquid water freezes and remains solid for a period. Familiar examples include glaciers, icebergs, sea ice, and frozen ground.1

In permafrost regions, where the ground remains frozen year-round, characteristic landforms are created by perennial ice. One such form is the "ice lens," which develops when abundant groundwater freezes in a confined area, creating a lens-shaped ice body. These can grow into conical mounds called pingos. The freeze-thaw cycle is a powerful agent of physical weathering, as freezing water expands and can break rock.2