Plate Tectonics


Margin Types
	Divergent Margins : Spreading Centers Tension - New 
Oceanic Crust
	Convergent Margins : Compression
		Ocean/Ocean
		Ocean/Continent
		Continent

		Transform : Shear - lithosphere neither created 
nor distroyed


Historical Perspective



		Wegner -- Continental Drift
		Pangea -- Beginning of the Jurassic
		Laurasia and Gondwanaland
		Evidence strongest for the southern
		hemisphere continents


Divergent Margins



Tensile Stresses
Shallow Earthquakes
Grabens and Horsts
Oceanic Lithosphere - basalts and gabbros
Magnetic "stripes"
Ophiolites










Convergent Margins


Shallow, intermediate, and deep focus earthquakes
high heat flows, active continental margins
molasse deposits
turbedites





Mechanisms -- Driving Forces


Variations in margin types
Mechanisms
Hot Spots