ERS120H5 Lecture 2: Plate Tectonics 1 lec 2
22 Jan 2016
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The continental crust is thicker, and ocean crust is thinner. Lithosphere (crust and uppermost mantle): thin, cool and hard. Consequence: plates can move around and interact with each other. Lithosphere is broken into large fragments called plates. Plates float at an elevation depending on thickness and density. The origins of the continents and oceans in 1915. Suggested that land masses slowly move (continental drift) Considerable criticism at the time: fit of the continents: Overlap and gap between south america and africa. Africa and south america gap: matching rock units: Continental shelf that separates africa from south america: matching mountain belts. Distinct rock assemblages and mountain belts match across the atlantic. And archean crust in many parts of africa and some in south america. Proterozoic belts on the edges of north america, africa, greenland and. Proterozoic mountain belts in africa and a bit of south america: matching fossil evidence. Non-swimming reptiles/ mammals could not have crossed an ocean.
