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Published byRodger Robbins Modified over 9 years ago
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Plates on the Move Three kinds of boundaries between plates “Divergent” – pulling part “Convergent – pushed together “Transform fault” – slide past each other
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Divergent Boundaries Plates pull apart & leave a gap Magma fills gap, cools and hardens Examples: Mid – Atlantic Ridge (beneath ocean) Rift between North American plate and the Eurasian plate in Thingvellir Iceland
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Convergent Boundaries Plates ram into each other Subduction process One plate cycles under other Recycles earth’s crust
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Oceanic plate converging with Continental Plate Result: Oceanic plate is “subducted” under the continental plate Example: Juan de Fuca plate pushing under NA plate
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Oceanic plate converging with another Oceanic plate Result: form a “trench” where one oceanic plate slips under another Example: Mariana trench Convergence between Pacific plate and Phillipine plate
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Continental Plate converging with Continental Plate When two continental plates meet do not subduct Instead crust buckles upwards forming Mountains (peak) Plateaus (flat) Eg. Tibetan Plateau
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Transform Fault Boundary Two plates slide by each other Most under ocean San Andreas Fault Few land based TF Pacific Plate sliding past North American plate
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Complete the missing information Place on Earth Type of Boundary Description of Plate Movement Thingvellir RiftNA plate pulling away from the Eurasian plate Juan de Fuca Plate (oceanic plate) Convergent Boundary (Oceanic + Continental) Tibetan PlateauIndian plate pushing up Eurasian plate San Andreas FaultTransform Fault Boundary
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Answers Place on Earth Type of Boundary Description of Plate Movement Thingvellir RiftDivergent BoundaryNA plate pulling away from the Eurasian plate Juan de Fuca Plate (oceanic plate) Convergent Boundary (Oceanic + Continental) Oceanic plate subducting beneath NA Plate Tibetan PlateauConvergent Boundary (Continental + Continental) Indian plate pushing up Eurasian plate San Andreas FaultTransform Fault BoundaryPacific Plate sliding past NA Plate
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At a Divergent boundary the plates are moving apart. The plates move apart due to convection currents inside the Earth.platesconvection currents As the plates move apart (very slowly), magma rises from the mantle. The magma erupts to the surface of the earth. This is also accompanied by earthquakes.magma When the magma reaches the surface, it cools and solidifies to form a new crust made up of igneous rock. This process is repeated many times, over a long period of time. Eventually the new rock builds up to form a volcano. Divergent Boundaries tend to be found under the sea, e.g. the Mid-Atlantic Ridge. Here, chains of underwater volcanoes have formed along the plate boundary. One of these volcanoes may become so large that it erupts out of the sea to form a volcanic island, e.g. Surtsey and the Westman Islands near Iceland.plate boundary
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At a convergent boundary the plates are moving towards each other. This usually involves a continental plate and an oceanic plate. The oceanic plate is denser than the continental plate so, as they move together, the oceanic plate is forced underneath the continental plate. The point at which this happens is called the subduction zone. As the oceanic plate is forced below the continental plate it melts to form magma and earthquakes are triggered. The magma collects to form a magma chamber. This magma then rises up through cracks in the continental crust. As pressure builds up, a volcanic eruption may occur.magma chamber
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