STUDY GUIDE - Plate Tectonics
Plate Tectonics:
Continental Drift and Pangaea: 1915, Alfred Wegener , fit of continental shorelines, continuity of mountain ranges, continuity of glacial moraines and striations, similar rock types, similar fossils; problems: but HOW? no mechanism for plate movement, prejudice
Sea Floor spreading: mid-ocean ridges, volcanic iron-rich lavas (magnetic), creating new oceanic rocks; problems: is Earth getting bigger? What happens on other side of spreading continents? Are ocean rocks destroyed?
Plate Tectonics: Earth's surface is split into plates of rigid lithosphere "floating" on hot, mushy asthenosphere, plates move apart at mid-ocean ridges where new oceanic rocks are created by volcanism, oceanic rocks are destroyed at subduction zones, continental rocks are neither created nor destroyed, therefore may be very old
divergent boundaries: plates move away from each other, new ocean lithosphere created at mid-ocean ridges, can use age of seafloor to determine past plate motion, small/med. shallow earthquakes, gentle lava flows
convergent boundaries: plates move toward each other, subduction zone, ocean crust destroyed at depth, trench, forms volcanic arc or volcanic island arc, huge, deep earthquakes; continental collision , folding and faulting as huge mountains form, continents sutured together
Transform boundaries: lateral motion of plates, lithosphere neither created nor destroyed, no volcanoes, small/large shallow/med. earthquakes, distinctive landforms
Hot Spots: stationary magma plume creates chain of volcanoes, with youngest on top of the plume, used to determine the direction and rate of plate motion
Describe the evolution of the theory of plate tectonics from continental drift, through seafloor spreading, to plate tectonics. What pieces of evidence did Wegener use in his initial proposal of Pangaea? Why was his idea not generally accepted for years?
Describe the three basic types of plate boundaries, the motion of plates at each boundary, their effect on the creation or destruction of lithosphere, and their surface expression.
What are hot spots? How do they form? How are they used to determine the past motion of plates?
Determine rate of plate motion from ocean floor spreading or hot spot.