ERS120H5 Lecture Notes - Lecture 3: Subduction, Continental Crust, Continental Drift
Document Summary
Continental - 0-70km hic, usually 35km, low density. Describe the difference between continental and oceanic crust (approximate thickness and density) and between the lithosphere and asthenosphere (approximate thickness and rigidity). Explain the basic tectonic model (thin, rigid lithosphere over weak asthenosphere, interacting plates) Lithosphere is thin, cool and rigid/strong and floats over the weaker hot asthenosphere. The lithosphere is broken up into several fragments called plates that float on the asthenosphere and can move around and interact with each other -- collide, overcome or float away from. Define isostacy and describe how it explains why the oceans are below sea level & the continents are, for the most part, above sea level. different heights so that they produce the same pressure. Oceanic crust is denser than the continental crust so it is not as buoyant as the less dense continental crust. Because the continental crust is more buoyant it will float higher than the heavier oceanic crust.
