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Name __________________ Looking at the world map, what do you notice about the shape of the continents? The thing is…the world didn’t always look like this! It used to look like this: How is this possible?!?!? Plate Tectonics Theory o The lithosphere is ____________ into a number of large and small _____________ and the plates are floating on the ______________ Lithosphere = the Earth’s ______________ plus the upper portion of the _____________ layer Plate Boundaries Divergent Boundary: o o Plates are moving ___________ from each other Midocean ridges are ____________ and ___________ ocean floor plates are created Convergent Boundary: o Plates are moving __________ each other and are colliding (3 types) 1. When Ocean Plates collide with Contintental Plates _____________________________, trenches Create near coast volcanoes ______________ __________ zones (a pattern of earthquakes as an ocean plate grinds down the underneath side of a continent) 2. When ocean plates collide with other ocean plates ___________________ are created (a pattern of volcanic islands created from a subduction zone that is located off the coast) 3. When a continental plate collides with another continental plate ______________________ are created (example: Himalayan Mountains) Transform Fault Boundary o o o o Plates are neither moving toward nor away from each other, they are moving ______________________. The plates may move in _____________ directions or in the _________ directions but at different rates and frequent _____________ are created (example: San Andreas Fault) Plates are destroyed as fast as they are created (2 ways) Plates may be subducted and ____________ or may push be pushed upward to form ______________ How can Oreos model the plate boundaries? Very carefully, take just the top cookie off the Oreo. Break the top cookie into 2 equal halves. Replace the cookie halves back on the Oreo Using the cookie, Demonstrate a transform fault boundary Demonstrate a divergent plate boundary Demonstrate a convergent plate boundary Seafloor Spreading Theory: Ocean floors are moving like broad ______________________ New ocean floor crust is being created at the _______________________________ What causes this? ___________________________________ within the mantle The up-welling leg of the current creates a _____________ boundary which produces _______________________________ The down-welling leg of the current creates one type of ________________ boundary that results in ________________ and a ________________ zone What evidence do we have to support this idea? Midocean ridges are ________________ than surrounding ocean floors ____________________________ on ridges, earthquakes on ridges Midocean ridge rocks are _____________ than surrounding ocean floor rocks Midocean ridge volcanoes are _________________ than volcanoes further away Ocean floor sediments are _______ on the ridges and get ____________ as the distance from the ridges increase Polar reversal magnetism proves that the ocean floor is moving away from the ridges Speed of Spreading Atlantic Ocean – _________ cm/year South Pacific Ocean – __________ cm/year Continental Drift Theory The __________________ have shifted their position over geologic time and at one time all land masses were ____________ into one piece called _________________ o Pangaea began to split apart 200 million years ago o Diagram Laurasia Pangaea Gondwanaland North America Greenland Eurasia West G. East G. Africa S. America Antarctica Australia India The continents are like packages on the seafloor conveyor belt. What evidence do we have to support this idea? o o o o High percentage __________ of continents at the 500 fathom level Minerals, fossils, and mountains on now ______________ continents ___________ if the continents were together Glaciation patterns indicate a ___________ ice cap at the South Pole ________________________ (magnetism of old rocks) indicate a common pole if the continents were all connected