Anthropology 2229F/G Lecture Notes - Lecture 16: Seafloor Spreading, Volcanic Glass, Magnetite
18 Jul 2012
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Lecture 16 archaeomagnetism, obsidian hydration, amino acid. Racemization: done through paleoorientation, magnetic field of the earth has varied over time. Location of magnetic north is not always the same. E. g. magnetite in atlantic seafloor spreading: strength/intensity of magnetism has also varied over time, clay or clay soils are heated to certain temperatures. Acquire a weak permanent magnetism when heated. Iron aligns to where magnetic north is at the time, reflects the direction/location of magnetic north. Will preserve magnetism: do have to know over time where magnetic north was; need a master chronology to compare it to. Similar to dendrochronology: can get a very accurate date, within 10-15 years. Obsidian hydration: obsidian volcanic glass. Formed when lava cools very quickly, minerals are quenched and crystals don"t have time to form/grow. Creates very sharp edges; good for cutting/scraping tools, etc: hydration rind/layers form on the surface from the reaction with the obsidian with the air.
