A nunatak is the summit or ridge of a mountain that protrudes from an ice field or glacier that otherwise covers most of the mountain or ridge. They often form natural pyramidal peaks. Isolated nunataks are also called glacial islands, and smaller nunataks rounded by glacial action may be referred to as rognons.

A glacier is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.