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Plate Tectonics Evidence (MAGNETISM (magnetic field reversal seen at land…
Plate Tectonics Evidence
BATHYMETRY
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Harry Hess
echo sounding sonar measurements of the oceans depths, proposed "seafloor spreading"
SF S = magma rises at ridges, creates new seafloor, sinking into trenches, moves continents apart
MAGNETISM
magnetic field reversal seen at land volcano lava's, dated to reveal history of reversal
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Striped pattern parallel to ridges of normal + reversed magnetic polarity fro magnetic iron rich mineral (magnetite). Striped due to periodic reversal of Earth's magnetic field
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non-north pointing magnetite in cont rocks, shows conts moved
DEEP SEA DRILLING
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Cooling magma records the polarity of magma, as crystals align in diff directions
EARTHQUAKE DISTRIBUTION
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Wadati-Benioff Zone - 100s km long seismic zones dipping at 40-60o parallel to trenches, where ocean floor sinks
Located at ocean ridges and trenches, shows plate movement
Earthquake focus gets deeper the further the distance from plate boundary - evidence of plate sinking
AGE OF ISLAND CHAINS
1963 - Tuzo Wilson
Classed as the father of plate boundaries, as noticed the Hawaiian islands get older moving in NW, due to fixed "hot spot" rising magma plume of mantel.
Plates movement determines the chain
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