CEE 1030 1nd Edition Lecture 12 Plate Tectonics Outline of Last Lecture I What is an earthquake II Seismology III Distribution of earthquakes IV Measuring the size of earthquakes V Earthquake damage VI Can earthquakes be predicted VII Review Outline of Current Lecture I Review II Plate tectonics III Geomagnetic reversals IV Magnetism of seafloor rocks V Workings of plate tectonics a Three types of plate boundaries VI Plate tectonics predictions VII What drives plate motions VIII Review continued IX Measuring plate motion Current Lecture I II III Review a In a basin the youngest rocks are in the center of a syclical structure Plate tectonics a Scientific Revolution in the late 1960s was the unifying concept of Earth Sciences b Continental drift hypothesis movement of continents across surface i Geometric evidence computer best fit model using continental slope rather than coast ii Fossil evidence land dwelling creatures are found across continents iii Paleoclimate evidence evidence for ice sheets on continents iv Geological evidence close match of rock types between continents c Supercontinent Pangaea d Objections to continental drift hypothesis Geomagnetic reversals a Earth s magnetic field periodically changes polarity These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute IV V VI VII VIII IX Magnetism of seafloor rocks a Symmetrical linear anomalies across ridges b Plates move apart new oceanic crust is formed Workings of plate tectonics a Lithosphere outer rigid shell of Earth i Consists of uppermost mantle and overlying crust ii Divided into plates iii Plates in motion relative to each other iv Astenosphere weak ductile mantle below the lithosphere b Seven major plates and several smaller ones c Three types of plate boundaries i Interactions among individual plates occur along boundaries 1 Transform slide past each other a Most join two segments of mid ocean ridge along breaks in oceanic crust known as fracture zones 2 Divergent seafloor spreading at ocean ridges creation of new oceanic crust a Continental rifting continental crust splits at rift can lead to creation of new ocean 3 Convergent continuous creation of ocean lithosphere Plate tectonics predictions a Explains global distribution of earthquakes What drives plate motions a Plate tectonics are a response to the cooling of the Earth b Thermal convective flow in the solid mantle c Heat makes mantle more buoyant rises and falls as it cools d Slab pull sinking of dense oceanic lithospheric slab e Hot spots and mantle plumes i Rising plumes of hotter mantle material that is stationary ii Plate moves across hot spots to create volcano chains Hawaii Review continued a Tectonic plates move about 10 cm year Measuring plate motion a Oceanic floor magnetic anomalies and magnetic time scale age of oceanic crust and spreading rate
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