GEOL107 Chapter Notes - Chapter 19: Continental Drift, Seafloor Spreading, Mid-Ocean Ridge
9 Nov 2018
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Chapter 19 plate tectonics - the unifying theory. Continental drift = idea that continents move freely over earth"s surface, changing their positions relative to one another. Seafloor spreading - hypothesis that the sea floor forms at the crest of the mid-oceanic ridge, then moves horizontally away from the ridge crest toward an oceanic trench. Wegener reassembled the continents to form a giant super-continent, pangaea. Also reconstructed old climate zones from evidence preserved in sedimentary rocks. Polar wandering - ancient poles were in different positions than the present poles. The continents remained motionless and the poles actually did move - polar wandering. The poles stood still and the continents moved - continental drift. Wegener proposed that continents plowed through the oceanic crust. Driving mechanism proposed by wegener for continental drift was combination of centrifugal force from earth"s rotation and gravitational forces that cause tides. Paleomagnetism - the study of ancient magnetic fields.
