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Unformatted text preview: Lecture 6- Earth as intergrated, Beginning of Evolution A. Evidence from Magnetism- &#2; Lines of force from Earths magnetic field resembles those produced by a bar magnet, magnetic field on Earth varies in strength through time, can reverse &#2; Periods of normal and reversed magnetic fields become locked in rocks as they cool B. Magnetic anomalies- lay across the sea floor, symmetric about axis of mid-ocean range where crust is created &#2; Lateral motion caused by convection cells, some movement likely also from the tug of plates at subduction zones, also likely from the tug of plates C. Radiometric age dating of sea floor- youngest is the mid ocean ridge, oldest towards the continents &#2; Plate tectonics explain distribution of earthquakes and volcanoes D. Hydrosphere- The Earths surface is covered by almost 71% oceans, no other planet in our solar system has liquid water on its surface &#2; Liquid water may exist under the surface of some planets &#2; Hydrospher- All the water on Earth, oceans, lakes, rivers, ice, air, soil, etc...
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- Winter '08