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f99u3le2 - ANTARCTIC Lesson 2 Antarctic Oceanography...

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©P ROJECT O CEANOGRAPHY A NTARCTIC O CEANOGRAPHY 100 A NTARCTIC Lesson 2. Antarctic Oceanography: Component I - Ice/Glaciers Component II - Marine Snow Lesson Objectives: Introduces students to the different kinds of ice found in Antarctica, Students will become familiar with ice sheets, icebergs and glaciers. Marine snow is found in the oceans surround Antarctica. We will discuss what it is and what function it serves to our oceans. Component I - Ice/Glaciers Antarctica's cold, thick hard covering, called an ice sheet, began to form 25 million years ago. Approximately 98% of Antarctica is covered by ice. Antarctica actually changes size – during the summer months (October-March), the coastal ice melts and Antarctica "shrinks." Although almost all of Antarctica's land mass is covered by ice, in a few places on the continent, mountain peaks poke through. The Transantarctic Mountains divide the areas of the continent known as West and East Antarctica. A glacier is a huge mass of ice, formed from compacted snow, whose sides are often bounded by mountains or the walls of a valley. Ice sheets, or caps, which are also formed from compacted snow, are so massive that they cover entire landscapes, mountains as well as valleys. Glaciers and ice sheets flow slowly toward the sea where the temperature is slightly warmer. This causes chunks of ice to break off; since ice is lighter than water, it floats when it reaches the sea. Once these chunks of ice are free- floating, they are called icebergs . The process of "birthing" an iceberg is called calving . Only about one-tenth of the iceberg is visible above water. The largest iceberg ever recorded measured 200 miles by 60 miles.
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©P ROJECT O CEANOGRAPHY A NTARCTIC O CEANOGRAPHY 101 A NTARCTIC Parts of the West Antarctic ice sheet rest on the sea floor and are less stable than the ice on land. Scientists carefully monitor it to see whether it will be affected by global warming. If the temperature rises, large parts of the ice sheet will melt and float freely. As they float, these ice sheets will move toward a warmer climate and begin to melt, leading to a sharp increase in sea level which would cause severe flooding on a global scale. Component II - Marine Snow Marine snow is the debris or dust that falls through the oceans and settles on the sea floor, the same way as dust in the air settles on an object in your home. The difference is that this ocean dust is full of nutrients and life. Marine snow helps transport material from the surface ocean to the deeper layers of the sea. Scientists believe marine snow is a major food source for life in the abyssal deep, bringing important nutrients into the deep sea while carrying with it diverse populations of microorganisms. This marine snow consists of bits of dead
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