EESA06H3 Chapter : Mantle.docx
Document Summary
Chapter 2 plate tectonics: earth surface is divided into large plates that move around and change in size. Glacier striation , evidence of the division of plates. Continents form before pangea, 2 billion years ago. Sea floor spreading happening because of convection, hot mantle low density,cool mantle high density and sinks. Basalt eruption occurs at the ridges where hot mantle is in the middle of melting and cooling. As hot rock moves, it carries basalt(oceanic crust with it) and bring it down to mantle as it cools, forming oceanic trenches- benioff sone earthquakes,andesitic volcanism (isalnd arc, are associated. Lithosphere increases in thickeness, further away from the ridge. Divergent plate boundry , convergent anda transform bounry : slide horizontally to each other. Magnetic reversal: reverse on average 500 000 and takes at least 10 000. Strike slip fault: earthquakes along the entire fracture zone. Ture:suggester by j tuzo wilson-transform fault: both ridges are active and form earthquakes only between two widges.
