EESC04H3 Lecture 4: Lecture 4 (2010 fall semester)
25 Jun 2011
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Document Summary
earthquake activity defines the margins of plates. Low density materials on top of the plates are continents. changes from the paleozoic time can be reconstructed. a mosaic of huge plates (10"s of kms thick; 1000"s of kms wide) plates interact with neighbours, results in crustal stresses reflected by earthquake activity at margins. Zones of spreading: represented by mid-ocean ridges; reflect tensional stress; expose lower density plates (continent) Zone of subduction: the denser plate goes down and forms ocean trench. orogeny: forces and events leading to severe structural deformation of earth"s crust due to engagement of plate tectonics. crust => upper mantle => mantle => outer core => inner core. asthenosphere => conveyor belt: a highly viscous mechanically weak ductilely- deforming regions of upper mantle of earth; lies below lithosphere. Identify areas that acted as separate continents: positions these paleocontients in their correct orientations, compile data indicative of geographical and climatological features.
