GEOL 306 Lecture Notes - Lecture 3: Supercontinent, Asthenosphere, Geosyncline
7 Feb 2018
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Lithosphere: crust + upper part of mantle, 100-150 km thick, rigid, Asthenosphere: below lithosphere, plastic (ductile), can flow in timescale of years or decares. Flow in liquid iron creates electric currents, creates magnetic field. Every several hundred thousand years, n/s switch. Some minerals preserve a record of direction and intensity of the magnetic field when they form. Name comes from vulcano, an island off the coast of italy. Many theories to explain origin and formation of mountains, volcanoes, earthquakes. Romans thought that hot lava fragments and clouds of dust erupting from vulcano came from vulcan"s forge. Hawaii: p l goddess of volcanoes lives in kilauea volcano in. Hawaii, triggers earthquakes by stamping feet, volcanoes by digging with her magic stick. Swam from island to island to escape sister, creating craters. Devils tower:wyoming: native american legend that rocky piston land rose to save seven little girls from a bear. Scrapes along the side of the mountain are bear claw marks.
