ERS120H5 Lecture Notes - Lecture 3: Isostasy, Continental Crust, Magnetization
23 Oct 2017
School
Department
Course
Professor
Document Summary
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/cm ) Oceanic crust: ~10 km thick, higher density (heavier 3. 2 g/cm ) 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: cork oceanic crust, oak continental crust, pine lithosphere, water asthenosphere. Alfred wegner"s observations (~1915: fit of the continents. If you rearranged the continents it seems as though they would fit like pieces of a broken plate: matching rock units and mountain belts, matching fossils. Fossils of the same creatures found on different continents, implying hat the creatures didn"t swim across the oceans but rather were once able to walk over to the other continent: matching paleo-climate belts.
