Thursday, November 12, 2009
Reading and Questions Set #3: pg. 202-204, question #1
1) A shield volcano is built of basaltic magma and it has a wide base and gently sloping sides. They can also be very big. A Cinder Cone is formed of pyroclastic material. They are the smallest types of volcanoes and they form in groups. They are different because a shield volcano can be very large and a cinder cone is very small. They are formed of different material, a cinder cone is formed of pyroclastic material and a shield volcano is formed of basaltic lava spreading slowly down the sides.
Reading and Questions Set #2: pg. 199-201, questions 1-3
1) They are different because they all have different viscosity, how explosive they are, and the different colors they have. Basaltic magma is found at oceanic hotspots and at mid ocean ridges, it has low viscosity and is a dark, dense rock.
2) Pahoehoe lava is smooth flowing, and cools into smooth rope-like shapes. AA lava is slow moving, and it cools into jagged shapes. Pillow lava erupts and cools underwater, it is very smooth when it cools.
3) Rhyolithic and Andesitic magma are associated with more explosive eruptions because they are the most explosive types of magma and they have the highest viscosity.Basaltic magma is associated with less explosive eruptions because it is the least explosive type of magma and it is the least viscosity.
2) Pahoehoe lava is smooth flowing, and cools into smooth rope-like shapes. AA lava is slow moving, and it cools into jagged shapes. Pillow lava erupts and cools underwater, it is very smooth when it cools.
3) Rhyolithic and Andesitic magma are associated with more explosive eruptions because they are the most explosive types of magma and they have the highest viscosity.Basaltic magma is associated with less explosive eruptions because it is the least explosive type of magma and it is the least viscosity.
Monday, November 9, 2009
Pages 194-197, Questions 1-3
1) Water in the subducted rock is released into the athenosphere, the water lowers the melting point, leading to the formation of magma. When the subducting plate melts, the magma gets less dense and rises.
2) At a hot spot, the magma is straight from the core, it pushed upward through the crust. It doesn't matter what kind of plate is at the boundary, because it rises in the middle of the plate. At the subduction boundary, the process of making magma is much different and the volcanoes at the subduction boundary have different magma than at hot spots.
3) At a divergent boundary, the plates split apart and magma is formed by the combination of low pressure and high temperature, then the magma is pushed up through the crust, and new crust is formed by the cooling magma.
2) At a hot spot, the magma is straight from the core, it pushed upward through the crust. It doesn't matter what kind of plate is at the boundary, because it rises in the middle of the plate. At the subduction boundary, the process of making magma is much different and the volcanoes at the subduction boundary have different magma than at hot spots.
3) At a divergent boundary, the plates split apart and magma is formed by the combination of low pressure and high temperature, then the magma is pushed up through the crust, and new crust is formed by the cooling magma.
Subscribe to:
Posts (Atom)
