mantereenjäätikköjä

Mantereenjäätikköjä, also known as continental glaciers or ice sheets, are vast, permanent masses of ice that form on land. They are distinguished from smaller ice caps and valley glaciers by their immense size and their ability to cover entire continents or large parts of them. Today, the only two extant continental ice sheets are the Antarctic ice sheet and the Greenland ice sheet.

These enormous ice bodies originate from the accumulation and compression of snow over many thousands of years. As more snow falls, the lower layers are compressed under the immense weight of the overlying ice, transforming into denser glacial ice. Continental glaciers flow outwards from their thickest points due to gravity, shaping the underlying landscape through processes like abrasion and erosion. They can carve out large valleys, fjords, and basins, and deposit vast amounts of sediment, known as till, as they advance and retreat.

The formation and melting of continental ice sheets have had profound impacts on Earth's climate and sea levels throughout geological history. During glacial periods, large ice sheets covered significant portions of the Northern Hemisphere, leading to lower sea levels as water was locked up in the ice. Conversely, their melting during interglacial periods has caused substantial sea-level rise. The study of these ice sheets provides crucial insights into past climate conditions and future climate change scenarios.