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Graduate Student Welcome Week September 2, 2014

Introduction – Olivia Jensen. Graduate Student Welcome Week September 2, 2014. about Olivia…. Born… in the deep winter of 1943 in a farmhouse in Springbank, Alberta Educated… in the public schools of Calgary, Vancouver and at the University of BC

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Graduate Student Welcome Week September 2, 2014

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  1. Introduction – Olivia Jensen Graduate Student Welcome Week September 2, 2014

  2. about Olivia… • Born… in the deep winter of 1943 in a farmhouse in Springbank, Alberta • Educated… in the public schools of Calgary, Vancouver and at the University of BC • Joined McGill’s Faculty of Engineering in 1973 and then Faculty of Science in 1984 • Married: 1975 – son of 34, daughter of 32, both McGill graduates; grandson 6, granddaughter 3 • Divorced: 1989 • “Transition”: 1989 with some following medical interventions

  3. Questioning the Faith Elements of faith in geology and geophysics • Uniformitarianism • Layered structure • Magnetic field generation • Interior rheology • Age, formation, composition • Interior mineralogy and temperature

  4. Answering the questions Principle of Uniformitarianism • Generalized covariance is inherent to the two great theories upon which our physics is constructed: • Quantum Mechanics • Gravitation (General Relativity) • These two theories are thought to be only insufficient to describe nature before 10-33 seconds following the Big Bang. • They have, so-far, failed no empirical tests. • Geological and geophysical processes since BB+10-33s follow the “laws” of physics... hence PofU?

  5. Answering the questions Layered Structure • Seismology finds global radial variations in physical properties α and β at many nearly fixed depths within the Earth. ~5-70 km 410 km 660 km ~2700 km ± 2890 km 5150 km

  6. Answering the questions Interior Rheology • Isostatic recovery from glacial loading and lateral tectonic plate motions suggest a different layering, especially of the outer regions. 0 – 200 km (~elastic) to ~400 km (~low viscosity fluid) to ~2900 km (~higher viscosity) to ~5100 km (very low viscosity) to 6375 km (~soft elastic) Rheological hack: eshear = (t/2η + 1/2μ)σshear

  7. Answering the questions Magnetic field • While some other generation processes have been argued, our only tenable model for field generation at present is a self-exciting magneto-hydrodynamic dynamo. • Given a pre-existing magnetic field, electrical currents are generated in a conductor (the fluid of the “iron” outer core) moving (why?) through it. • The magnetic field necessarily associated to these currents becomes aligned with pre-existing field due to coriolis forces within the core due to Earth's spin!

  8. Answering the questions Age, formation, composition • Age? Tight at 4.567Ga... if Earth formed coincident with age-determined meteorites! … but • Formation? Ever more new models are still being proposed and discounted! • Composition?Modelled on Estatite chondrites? Fashionable but it doesn't explain Fe!

  9. Answering the questions Interior Mineralogy and Temperature Profile

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