GEOL107 Lecture Notes - Lecture 20: Continental Drift, Seafloor Spreading, Arthur Holmes
13 Nov 2018
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Document Summary
Geographic fit of now separated continents (like pieces of a puzzle that could be put back together) Geology (rocks and fossils) of now separated continents very similar. Joining of continents in one large landmass could explain large glacial event. Sir arthur holmes in late 1920s proposed thermal convection as a driving force for continental drift - thermal convection is transfer of heat by physically moving hot stuff to colder areas and colder stuff to warmer areas. Continents ride on top of upper mantle convective currents. Explanation for apparent wandering of earth"s magnetic poles. About 70% of all earth"s volcanic activity occurs. Mapping of world-encircling mid-ocean ridge (where new oceanic crust created) (1) Age of oceanic crust increasing away form mid-ocean ridge (2) Discovered by correlating marine magnetic anomalies with known times of reversals of earth"s magnetic field. Generated by complex interactions of moving currents of liquid iron/nickel in.
