Large accumulations of thickened crystalline ice masses on the Earth's surface are called Glaciers.
Glaciers form when snow remains in one location for long enough to transform into dense hard ice. This usually occurs in mountainous areas that have both cold temperatures and high precipitation. But snow can also accumulate and turn into ice in extremely cold low lying areas such as Greenland and Antarctica. Glaciers cover about 10% of the surface of the Earth, and are powerful erosional agents that sculpt the Earth's surface.
Glaciers are often termed as 'rivers of ice' as well.
Study of Glaciers is called Glaciology. It is an interdisciplinary study that integrates Earth science, geophysics, geology, geography, geomorphology together.
Types of Glaciers
There are two major types of glaciers:
Alpine glaciers form in mountainous areas either at high elevations or near cool and wet coastal areas. A common type of alpine glacier is a valley glacier which is confined to a long, narrow valley located in mountainous areas especially at higher latitudes (closer to either the north or south pole). Alpine glaciers are also sometimes referred as Mountain glaciers or Valley glaciers. (see Figure 1)
Most alpine glaciers are located in the major mountain ranges of the world such as the Andes, Rockies, Alps, and Himalayas.
Continental Glaciers / Icesheet Glacier
Also known as Ice sheet or Ice caps. The are the massive sheets of thickened ice that spreads over a significantly large geographical area. (Image by NASA)
Where are Earth’s glaciers located?
Glaciers exist on every continent except Australia. Approximate distribution is:
91% in Antarctica
8% in Greenland
Less than 0.5% in North America
0.2% in Asia
Less than 0.1% is in South America, Europe, Africa, New Zealand, and Irian Jaya.
Why some glaciers are blue?
Large accumulation ice looks blue for the same reason large accumulation of water seems blue to us. The chemical bond between oxygen and hydrogen in water absorbs light in the red end of the visible light spectrum.
The Siachen Glacier is a glacier located in South Asian high mountain region or the "Hindu Kush - Karakoram - Himalayan" region is also sometimes referred as Third Pole. Siachen glacier is the longest glacier in the Karakoram region and second-longest in the world's non-polar areas.
Siachen glacier is specifically in the eastern Karakoram range in the Himalayas near the Line of Control between India and Pakistan.
Glacier v/s Iceberg
An iceberg is a large piece of ice that has broken off a glacier or an ice shelf and is floating freely in open water.
Tabular icebergs have steep sides and a flat top.
Non-tabular icebergs have irregular, non-typical shapes which include domes shape icebergs too.