40 mark question volcanic and seismic activity Model example
‘Volcanic and seismic events are major pieces of evidence towards proving that plate tectonics theory is valid.’ Discuss the extent to which you agree with this statement. (40 marks)
Over the years proceeding the birth of the theory, increasingly convincing evidence has been gathered for proof of the theory of plate tectonics. In 1912, Alfred Wegner proposed the theory that continents are sat upon tectonic plates and that these plates are slowly drifting around the Earth (continental drift). Since then, volcanic and seismic events have made up a large proportion of the evidence towards the theory, including volcanic eruptions at both constructive and destructive boundaries, hotspots, sea floor spreading, paleomagnetism, and seismic earthquakes. However, not all of the evidence supporting plate tectonics comes from volcanic and seismic events; other evidence includes continental fit, geological evidence, biological evidence, climatological evidence and other activity at destructive plate margins.
At a hotspot, the underlying mantle is hotter than average causing ‘mantle plumes’ to rise to the bottom of the lithosphere, find a thin or weak part of the lithosphere, and breaks through. In the case of the Hawaiian islands, the hotspot is underneath an oceanic plate and the lava has built up until it is higher than the surface of the sea. These hotspots remain in the same place in relation to the mantle, but the plates move across the hotspots. The Pacific plate has moved across a hotspot in the ocean leaving the chain of Hawaiian Islands which have been formed at different times over millions of years. By dating the rocks which make up the Hawaiian Islands, it is clear that the tectonic plate must be moving in relation to the hotspot- a key piece of volcanic evidence.
Sea floor spreading and paleomagnetism, although not direct volcanic activity, are caused by volcanic events and will therefore be considered ‘volcanic’ evidence towards the theory of plate
Over the years proceeding the birth of the theory, increasingly convincing evidence has been gathered for proof of the theory of plate tectonics. In 1912, Alfred Wegner proposed the theory that continents are sat upon tectonic plates and that these plates are slowly drifting around the Earth (continental drift). Since then, volcanic and seismic events have made up a large proportion of the evidence towards the theory, including volcanic eruptions at both constructive and destructive boundaries, hotspots, sea floor spreading, paleomagnetism, and seismic earthquakes. However, not all of the evidence supporting plate tectonics comes from volcanic and seismic events; other evidence includes continental fit, geological evidence, biological evidence, climatological evidence and other activity at destructive plate margins.
At a hotspot, the underlying mantle is hotter than average causing ‘mantle plumes’ to rise to the bottom of the lithosphere, find a thin or weak part of the lithosphere, and breaks through. In the case of the Hawaiian islands, the hotspot is underneath an oceanic plate and the lava has built up until it is higher than the surface of the sea. These hotspots remain in the same place in relation to the mantle, but the plates move across the hotspots. The Pacific plate has moved across a hotspot in the ocean leaving the chain of Hawaiian Islands which have been formed at different times over millions of years. By dating the rocks which make up the Hawaiian Islands, it is clear that the tectonic plate must be moving in relation to the hotspot- a key piece of volcanic evidence.
Sea floor spreading and paleomagnetism, although not direct volcanic activity, are caused by volcanic events and will therefore be considered ‘volcanic’ evidence towards the theory of plate