EESA06H3 Study Guide - Final Guide: High-Level Waste, Toffee, Environmental Science
11 Apr 2017
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Plate tectonics put the geology of n. a. together. Contain uranium isotopes which changes to lead and we can date the rock by the amount of lead it in. Produced in magma, very tiny crystals (size of human hair) Creates artificial earthquakes and maps up to 70km deep, uses two way travel time to calculate. Oldest is in the center and newer continental crust forms around it. Original continental crust were really small (3% crust, 97% ocean), now it is. We expect that it will be mostly crust in the future. Subduction converts oceanic crust into continental crust (basalt -> granite, gneiss ) Most subduction occurs with collision, when supercontinents come together, most growth of continental crust occurred. Slave provinces, rocks are really old and contain diamonds & very small. Slave provinces were the beginning of north america, ancestor continent. Little continents that joined with other continent, resulting in different aging.
