1. Name two mountain ranges, which were formed by the collision of continental plates.
   E.g. Alps, Himalaya, Ural, Kaukasus (for further information see world plate tectonics map).
    
2. Why are so many active volcanoes situated in the Andes?
   Answer: Where oceanic and continental plates collide, the oceanic plate is subducted, because its crust density is higher. As the oceanic plate descends into the hot mantle, parts of it may begin to melt. Rock melt (magma) forms and floats upward, some of it reaching the surface as lava erupting from volcanoes.
    
3. How did the Ural form and why is it lower in elevation than the Alps?
   The Ural and the Alps were formed by the collision of continental plates. But the Ural is older than the Alps, and therefore, erosion has been active for much longer. One day, the Alps will also be lower. At the moment, however, not only are the Alps eroding, but they are being uplifted due to the process of isostasy. For further information, see orogeny through time.
    
4. Diagram the rock cycle from memory and briefly describe the main processes.
   See rock cycle.
    
5. Which main rock type is dominant in the area where you life and why?
   If you don't know, check outside sources or at your library.
    
6. What consequences would it have for mountain formation and alpine ecology, if erosion and weathering did not exist?
   
   • Mountains would be much higher and would not become lower with time.
      
   • Mountains would look much different, because the sharp mountain peaks and deep valleys are mainly due to erosion and weathering.
      
   • Erosion transports fresh rock particles downward and provides nutrients for soils and vegetation. Hence, nutrient availability would be severely decreased. However, there would also be no erosion of alpine soils.
      
   There are clearly many more probable consequences. For further information also see Slope processes and alpine soils.
    
7. Why can sedimentary rocks, e.g. limestone with shells, sometimes sit on top of high mountains, although they were once deposited in an ocean?
   Plate tectonics make it possible. Once deposited in an ocean, rocks may be uplifted many thousand meters over millions of years due to plate collision (e.g. in the Alps or the Himalaya).

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29 August 2011
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