Earth Sciences 1070A/B Lecture Notes - Lecture 7: Continental Crust, Plate Tectonics, Oceanic Crust
18 Jan 2017
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America, australia, india and antarctica (2: many mountain belts stop at coast line and reappear on a continent across ocean (3, rocks in india evidence of glaciation and some rocks in north. Plates have changed their latitude positions on globes: concluded: supercontinent broke apart and continents drifted to current positions, limitation: proposed that continental blocks plowed through ocean floor. If true, then why did mountains not pile up at their leading edge. Solid continents float on semi-solid layer beneath (scum floating on pond) Archean and into precambrian era planet hotter plates tectonic processes were faster. Past 2 billion years, planet cooling and plate tectonic processes slowing down. Earth divided into layers based on changes in: composition, earth divided into crust, mantle, and core, crust. Cool, thin and divided into continental and oceanic crust. More buoyant and floats higher on top of mantle (beneath it) Felsic rocks with abundant o2, silica, aluminium. Dense mafic rocks with abundant magnesium and chromium: mantle.
