ERS120H5 Lecture 3: LEC #3 (Tectonic Plates)
16 Feb 2017
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Lecture #3 on the move: plate tectonics. Lithosphere is thin, cool, and hard: lithosphere broken into large fragments called plates. Asthenosphere is weak and hot: plates float on the asthenosphere. Plates move around and interact with each other. Continental crust: 35 km thick (0-70 km, low density (lighter 2. 65 g/cm3) Oceanic crust: ~10 km thick, higher density (heavier 3. 2 g/cm3) Lithosphere: ~100-250 km thick, relatively rigid. Asthenosphere: around 200 km thick, relatively ductile (easily deformed) Materials float at an elevation depending on thickness and density. Alfred wegner proposed the idea of pangea (greek for all lands ) Objections to pangea (at the time): hypothesis was incomplete didn"t provide a mechanism for continents to drift, we didn"t have the technology or data to test the hypothesis. In the 1960s, new research in the oceans changed everything. There are underwater mountain ranges, deep trenches, and a lot more to be found as seen in these charts.
