Get to know what a glacier is and the process of its formation
A glacier is a large lump of ice crystals, snow, rock, sediment, and often liquid water that originates on land and moves slowly down a slope, under the influence of its own weight and gravity. The term glacier comes from the French word glace (glah-SAY), which means ice. Because of this, glaciers are often called glaciers. Launching National Geographic, glaciers are divided into two groups, namely alpine glaciers or mountain glaciers and ice sheets.
Alpine glaciers form on mountain slopes and move downward through valleys. Occasionally, alpine glaciers create or deepen valleys by pushing dirt, soil, and other material out of their way. These alpine glaciers are found in the high mountains of every continent, except Australia (although there are many in New Zealand). The Gorner Glacier in Switzerland and the Furtwangler Glacier in Tanzania are both typical mountain glaciers. Alpine glaciers are also known as valley glaciers or mountain glaciers.
Whereas ice sheets, unlike alpine glaciers, are not confined to mountainous areas. They form a vast dome and spread from its center in all directions. As the ice sheets spread, they covered everything around them with a thick layer of ice, including valleys, plains, and even entire mountains.
The largest ice sheets, called continental glaciers, are spread over vast areas. Today, continental glaciers cover most of Antarctica and the island of Greenland. A large ice sheet covered much of North America and Europe during the Pleistocene time period.
This was the last glacial period, also known as the Ice Age. Where the ice sheet reached its greatest size about 18,000 years ago. As ancient glaciers spread, they carved out and changed the earth’s surface, creating many of the landscapes that exist today. During the Pleistocene Ice Age, nearly a third of the Earth’s land mass was covered by glaciers. Currently, about a tenth of Earth’s land area is covered by glacial ice.
Glaciers begin to form each year, in places where more snow is accumulating than melting. As soon as it fell, the snow began to accumulate and become denser. It slowly then changes from light and fine crystals to hard round ice grains. New snow keeps falling and burying the snowflakes. Then, the hard snow became denser. This dense, coarse ice is called firn. The process of compaction of snow into glacial firn is called firnification.
As time passes, the firn layers build on top of each other. When the ice grows thick enough — about 50 meters, the first grains melt into very large solid ice. The glacier begins to move under its own weight. Because glaciers are very heavy and exert enormous pressure, firn and snow melt without any increase in temperature. Melting water makes the base of the heavy glacier slippery and more spreadable across the landscape. Pulled by gravity, the glacier moves slowly down the valley. While some glaciers, called hanging glaciers, do not flow along the mountain. Avalanches and waterfalls will move glacier ice from overhanging glaciers to larger glaciers below, or directly into valleys below. A layer of ice spread from its center. Then the huge mass of ice on the glacier will be like plastic, or like liquid. It flows, seeps and slides over uneven surfaces covering everything in its path. Different parts of the glacier will move at different speeds. The ice flowing in the center of the glacier moves faster than the bottom, moving slowly along the rock layers. Keep in mind, although glaciers move slowly, they are very strong. Its power is like a huge bulldozer. They will plow and destroy almost anything that gets in their way. Forests, hills and mountain slopes are no match for glaciers.
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 …