Antarctica is often called "the ice continent" - almost completely it is covered with ice boards which thickness in some places reaches 4500 km. Here the biggest variety of types of natural ices is observed.
Instruction
1. Scientists allocate two large types of glaciers – integumentary and mountain. Antarctica is almost completely busy exactly with integumentary glaciers which have a number of distinctive features.1. Huge razmery2. Special, plano-convex forma3. The direction of the movement is connected first of all with plasticity of ice, but not with a relief glacial lozha4. There is no accurately expressed border between areas of a drain and food of a glacier. Integumentary glaciers are in turn divided into several types, each of which can be met in Antarctica.
2. 1. Glacial domes are a characteristic form of freezing, often meets in a coastal zone of Antarctica. Represents the dome-shaped mass of ice from 300 to 500 m high, width usually of 10-20 km. The form of a surface of an ice dome most often elliptic, is some kind of small center of accumulation of ice. An example of an ice dome is the island of Drigalskogo – it is located on a moraine near the Mirnyi station and has length of a dome of 20 km, and width – 13 km. According to scientists of draft do not compensate an ice consumption as a result of a splitting off of icebergs therefore the island decreases and in 300 years can disappear absolutely. Sometimes ice domes can be met also in regional areas of the continent and also in the sea near the coast in the form of certain ice islands.
3. 2. The cast glaciers – meet in "oases" of Antarctica generally on northwest slopes of a land relief in the form of big snowdrifts. This type of glaciers is formed as a result of methyl deposits of snow. As on a coastal zone of Antarctica strong southeast winds blow, the cast glaciers most often are formed on the northwest directions at leeward slopes of rocks.
4. 3. Output glaciers are some kind of ice rivers which are channels of a drain of ices from internal areas of the continent to coast. The sizes of output glaciers depend on the sizes of subglacial valleys, they are sometimes huge. As it is possible to give an example Lambert Glacier, about 450 km long and more than 50 km wide. It proceeds in mountains of Prince Charles on MacRobertson Land. Scientists contain several dozen large output glaciers in Antarctica. In spite of the fact that less than 10% of the coastline fall to the share of output glaciers, on them more than 20% of the ices which are annually dumped in the sea arrive. Besides, average speeds of the movement of such glaciers in comparison with other types, the highest and the nature of their surface restless.
5. 4. Ice shelf are the most widespread type of ice in Antarctica. Ice shelf do not meet in such volume, as on "the ice continent" anywhere. This type of glaciers received the name because meets in a zone of coastal shallow water, on the shelf. Their thickness can be small, they or float in the sea, or in places lean on islands or underwater banks. The area of ice shelf can be huge (for example, an ice shelf of Ross). Often inner edge of such glacier leans on a continental glacial cover, and external takes to the open sea, forming huge breaks to several dozen meters. From large ice shelf the huge icebergs reaching several hundreds of kilometers in the diameter sometimes break away. Scientists found out that ice shelf are formed due to running off of continental ice in the sea and also savings of snowfall.