A glacier is a large, perennial accumulation of crystalline ice, snow, rock, sediment, and often liquid water that originates on land and moves down slope. Glaciers are massive bodies of slowly moving ice that form on land when fallen snow gets compressed into ice over many centuries. They are found in cold regions where snow does not melt, and it just piles up and crushes the snow beneath it to form glaciers. Glaciers slowly move downwards, changing the shape of the topography as they go. Glaciers that move downwards carve out U-shaped valleys as they slide, and bits of rocks carried by glaciers collect to form ridge-like mounds called moraines.

Glaciers are usually divided into two groups: Alpine glaciers, which form on mountainsides and move downward through valleys, and Continental ice sheets, which spread out and cover larger areas. The world’s largest glacier is Lambert Glacier, located in Antarctica, measuring approximately 100km wide, 400km long, and 2.5km deep. Glaciers are important features in the hydrologic cycle and affect the volume, variability, and water quality of runoff. Glacier ice today stores about three-fourths of all the fresh water in the world, and they cover around 10% of the Earth’s total land area.

Glaciers and the landscapes they have shaped provide invaluable information about past climates and offer keys to understanding climate change today. Past glaciers have created a variety of landforms that we see in National Parks today, such as U-shaped valleys, cirques, horns, and hanging valleys. Glaciers are moving bodies of ice that can change entire landscapes. They sculpt mountains, carve valleys, and move vast quantities of rock and sediment.