GEOS 212 1st Edition Lecture 4 Outline of Last Lecture 1 History of spreading in South Atlantic North Atlantic Eastern Pacific Labrador Sea and Indian Ocean 2 Rates of spreading rate is distance time usually km my or cm yr a The edge of the continent is usually not sea level but the edge of thecontinental shelf 3 Pacific Plate also has chain of islands from hot spot Hawaii a Connection between mantle plume hot spot island chain b Rate of motion calculation distance time usually km my or cm yr 4 Subduction zones in continental and oceanic settings 5 Plate tectonics is the most efficient way for the earth to lose heat that s the simple reason that plates move 6 Early idea was that conveyor belt convection drives plate but it has problems 7 Some people now believe that plates slide away from ridges and toward subduction zones 8 World Tour of subduction zones Outline of Current Lecture Volcanoes 1500 could erupt 20 erupting most of the time Occur in four tectonic settings o o o Spreading centers Hot Spots Subduction Zones 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 o Continents Pulling Apart Two main types of volcanoes o Shield Volcanoes o On oceanic crust o Not steep sides o Basalt high iron very hot o Not explosive o Not Hazardous o Lava flows runny Strato Volcanoes o On continental crust o Steep sides o Andesite lower iron cooler stif o Explosive o Hazardous o Lava flows ash cinders pyroclastic flows Diagrams of Shield Strato Volcanoes Videos of shield volcano eruptions o of volcanoes below sea surface o Importance of Kilauea o Temperature of lava o Key to forecasting eruptions o Nature of magma o Nature of basalt color texture Videos of stratovolcano eruptions o What else comes from volcanoes besides magma o Pyroclastic flow made up of rock ash gases o Nature of magma o Nature of andesite ash color texture o How many potentially active volcanoes o How many people live at risk from volcanoes Cascade volcanoes in Oregon Washington Eruption history of the Cascade volcanoes Caldera eruptions Currently active Volcanoes http www geocodezip com v2 activeVolcanos asp Current Lecture
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