A glacier is a large body of dense ice, which is continuously moving under its own weight. Glaciers are formed over many years, or even centuries, in such places where the rate at which snow accumulates is more than the rate at which it undergoes ablation. Due to the stress induced by their own weight, glaciers slowly move leading to the creation of crevasses, seracs and other distinguishing landforms. Glaciers are formed only over land and they are distinct from the sea ice and lake ice which are much thinner and form over the surface of water bodies. Following report will answer your question “What is a Glacier?” in better way.
99 percent of the glacial ice on earth is contained in the vast ice sheets of the polar region. Glaciers are also found on mountain ranges of every continent except Australia. Himalayas, Andes, Rocky Mountains, some of the higher mountains in East Africa, Mexico, and New Guinea are all the mountain ranges where we can see glaciers. Glacial ice is the largest reservoir of freshwater on our planet earth. Most of the glaciers situated in the temperate, alpine and seasonal polar climatic regions store water as ice during the cold season. They then release it later as melt water during warm summer seasons when other sources of water become scanty. For glaciers formed in high altitudes, and in Polar Regions, even such seasonal variations in temperature are not sufficient to release melt water.
As said, glacier mass is not usually effected by seasonal climatic variations, and is more affected by the long term climatic changes such as precipitation, mean temperature changes, cloud cover etc. and hence changes in glacial mass is considered as one of the best indicators of climate change. It is also one of the major causes for variation in sea levels.
Formation of glaciers
Glaciers are formed in such places where the rate of accumulation of snow is higher than that of the rate of ablation. The landscape where glaciers usually form are called cirque, which has a typical armchair shaped geological feature where snow gets collected and accumulated over the years. The snow thus collected gets compressed because of the gravity and weight of the snow falling above it. This compression process squeezes out the air from the snow and turn it into glacial ice.
When the cirque gets filled with the glacial ice, it will start overflowing through the geological weaknesses or vacancies such as gaps between two mountains. Due to the combination of surface slope, gravity and pressure, the glacier starts to move forward. Glacier, which is essentially a large piece of compressed ice, would appear blue because of the large quantities of water that it contains. It is also because of the lack of air bubbles in the glacial ice. It is the air bubbles that give white colour to ice, in the case of glacial ice, air bubbles are squeezed out because of the pressure.
Let us see some of the interesting facts about glaciers:
Approximately 75 percent of the freshwater available on earth is in our glaciers.
About 10 percent of the earth’s surface is covered by different types of glaciers and the size of the area covered by them is depleting quickly.
Out of all the glaciers in the world, 99 percent of the glacial ice on the world is within the polar ice sheets.
There are different types of glaciers, based on the most common classification they can be in the form of alpine glaciers, ice caps or ice sheets. Alpine glaciers are the ones that are located in the mountain valleys. Ice caps or otherwise known as ice fields are also usually found on top of mountains. Ice caps are usually of size less than 50000 square kilometres. The other type of glaciers is the ice sheets or the continental glaciers. These types of glaciers are found in the polar region and are larger than 50000 square kilometres.
Glaciology is the branch of science that studies glaciers and their related processes.
Glaciers are very sensitive to climate changes and hence scientists across the world studies about glaciers to keep track of the variations in the earth’s climatic conditions.
When glaciers move, they also erode the terrain under them. This is mainly done through two different processes. Plucking is the first one. Through this process the bedrock is softened and levered out by sub glacial water which constantly undergoes refreezing along with making the sediment part of the glacial cargo. The other process is called abrasion. In this process the glacial ice and rocks which are part of the glacial cargo act like a sand paper and slides over the bedrock and thus essentially smoothening and polishing it.
Studying the glacial deposits helps to show where historical glaciers were and how they have moved over the years.
If all the glacial ice on earth melts, it would be enough to raise the sea level worldwide by approximately 70 meters.
The largest glacier in the world is the Lambert Fisher glacier in Antarctica. It is 400 kilometres long and up to 100 kilometres wide. It is so huge that this ice stream alone drains about 8 percent of the Antarctic ice sheet.
In some areas, the Antarctic ice sheet has a thickness of up to 4.7 kilometres. The continent has been at least partially covered by an ice sheet for the past 40 million years.
A glacier is a massive structure of ice, and ice alone. Constantly moving, it is mostly found in the Antarctic regions. Here are a lot of facts about glaciers that one should know.