A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity. A glacier is formed by ice accretion over the years in mountainous or sloping terrains. The glacier fringe is the area where the glacier has recently melted. There are two main types of glaciers: alpine glaciers, which are found in mountain terrains, and continental glaciers, which are associated with ice ages and can cover large areas of continents. Glacier ice is the largest reservoir of fresh water on Earth, second only to the oceans as the largest reservoir of total water. Glaciers are found on every continent except Australia, and the largest mountain glacier is the Siachen glacier in the Himalayas.