EPSC FINAL - Short Answer Topics Final Paleomagnetism and geomagnetic pole paths Earths magnetic eld Flow in the liquid outer core creates the magnetic

EPSC FINAL - Short Answer Topics Final Paleomagnetism and...

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Short Answer Topics- Final Paleomagnetism and geomagnetic pole paths  Earth’s magnetic ?eld Flow in the liquid outer core creates the magnetic ?eld. o It is similar to the ?eld produced by a bar magnet o The magnetic pole is tilted ~11.5 from the axis of rotation Geographic and magnetic poles are not parallel. A compass points to magnetic N, not geographic N. The di뮎erence between geographic N and magnetic N is called declination. It depends on: o Absolute position of the two poles Geographic north Magnetic north Longitude Curved ?eld lines cause a magnetic needle to tilt. Angle between magnetic ?eld line and surface of the Earth is called inclination. It depends on: o Latitude Magnetic poles The magnetic pole intersects Earth’s surface just like the geographic pole does o Magnetic N pole and magnetic S pole both exist o Magnetic poles are located near geographic poles o Magnetic poles move constantly. Rock magnetism can be measured in the laboratory The study of fossil magnetism is called paleomagnetism. Iron (Fe) minerals in rock preserve information about the magnetic 腹eld at the time the rocks formed o Declination and inclination preserved in rocks often vary from present latitude/ longitude. o Instruments used in paleomagnetism record changes in position o These data are used to trace continental drift Paleomagnetism Rock magnetism can be measured in the laboratory. The study of fossil magnetism is called paleomagnetism Iron (Fe) minerals in rock preserve information about the magnetic ?eld at the time the rocks formed o Declination and inclination preserved in rocks often vary from present latitude/ longitude o Instruments used in paleomagnetism record changes in position o These data are used to trace continental drift Iron minerals archive the magnetic signal at formation Hot magma o High temp—no magnetization
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Thermal energy of atoms is very high Magnetic dipoles are randomly oriented   The Juan de Fuca ridge and plate  Basic principles of plate tectonics DIVERGENT BOUNDARY Tectonic plates move apart Lithosphere thickens away from the ridge axis New lithosphere created at divergent boundary Also called: mid-ocean ridge, ridge. 
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CONVERGENT BOUNDARY Tectonic plates move together The process of plate consumption is called subduction Also called: convergent margin, subduction zone, trench. TRANSFORM BOUNDARY Tectonic plates slide sideways Plate material is neither created nor destroyed Also called: transform fault, transform. The Juan de Fuca ridge is a tectonic spreading centre located o뮎 the coasts of the state of Washington and the province of British Columbia
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It runs northward from a transform boundary, the Blanco Fracture Zone, to a triple junction with the Nootka fault and the Sovanco Fracture Zone To its east is the Juan de Fuca Plate, which together with the Gorda Plate to its south and the Explorer Plate to its north, is what remains of the once-vast Farallon plate which has
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  • Fall '09
  • ALFONSOMUCCI
  • Plate Tectonics, Igneous rocks, Volcano, false statement

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