Examine how a glacier operates as a system (25)

Examine how glaciers operate as a system. (25) Glaciers can be classified according to the temperature of their base. In warm based glaciers e.g. the Alps, the base is warmer than the melting point of ice. It’s warmer because of the heat from friction caused by the glacier moving, or because of the geothermal heat from the earth. The ice at the bottom of the glacier melts, and the meltwater acts like a lubricant, making it easier for the glacier to move downhill. Ice at the surface also melts if the temperature reaches 0 degrees Celsius, and meltwater moves down through the glacier, lubricating it even more. Therefore, warm based glaciers move rather quickly, lots of movement means lots of erosion so warm based glaciers are highly erosive too. On the contrary, in cold based glaciers e.g. in Antarctica where glaciers cover 13,586,380km, the base is cold and the temperature is usually well below the ice’s melting point, so there’s very little melting and this lack of meltwater means cold based glaciers move very slowly. The ice is frozen to the valley floor which also slows movement. Even in summer the temperature is below freezing, the mean annual temperature of the interior is −57°C, so there’s not a lot of melting at the surface either. Consequently, cold based glaciers don’t erode a lot. A glacier is a system which has inputs, outputs and stores. The main

  • Word count: 1465
  • Level: AS and A Level
  • Subject: Geography
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Three Gorges Dam

Dam the Three Gorges The Three Gorges are known to be a famous tourist attraction for its beautiful scenery, located in northeastern China along the Yangzi River. The Yangzi River runs 3700 miles long, being the third longest river in the world after the Nile and Amazon Rivers. The Qutang Gorge, the Wuxia Gorge, and the Xiling Gorge are the three Yangzi River gorges that make up the Three Gorges. The Three Gorges are not only famous for its scenery, but also its disastrous flooding. Within a century, five major floods have occurred killing over 300,000 people living in cities along the bank of the river. This is due to the constant sediment deposits along the river, causing the river bed to continuously rise six metres to seventeen metres higher than the plains. In 1992, the Chinese National People's Congress approved the project of constructing a dam at the upper and middle reaches of the Yangzi River by the Xiling Gorge. The purpose was to adjust the water flow of the Yangzi River in hope to prevent more serious flooding. The dam is expected to be the largest hydroelectric project in the world, being 185 metres (606 feet) high and 1,983 metres (6500 feet) broad, with a reservoir that will fill a level of 175 metres above sea level.1 The 17-year construction of the dam is estimated to use 10.8 million tons of cement, 1.9 million tons of rolled steel, and 1.6 tons of

  • Word count: 1383
  • Level: AS and A Level
  • Subject: Geography
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