GEO 303 Lecture Notes - Lecture 11: Shield Volcano, Eruption Column, Mafic
23 Dec 2017
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Lecture 11: plate tectonics, magnetic fields, and volcanism. S waves cannot pass through liquid ! creates a shadow zone near other end of. Cores of various bodies: moon: small or none, mars: normal-ish sized. Io: normal-ish; europa: small to normal; ganymede: small to normal; calisto: small to none: titan (saturn): almost completely core, mercury: ~45% core. Plate tectonics: theory: 12 rigid outer plates moving over softer (but still solid) upper mantle, continents carried along for the ride, driven by mantle convection, pangaea ! spreading ! formation of atlantic ! more spreading ! St. helens, volcanic islands, deep ocean trenches (mariana), coastal mountain ranges, earthquakes. & younger lowlands in the north: olympus mons & the tharsis bulge (unlike hawaiian islands, does not move; just kept building higher up, no magnetic field now, but did early in its history. Earth"s magnetic field: resembles a bar magnet, outer core: rapidly convecting due to heat escaping from the core to the mantle !
