ERS120H5 Lecture 2: Plate Tectonics - Jan 9th and 11th
Document Summary
Plate tectonic model: lithosphere thin, cool, hard shell, asthenosphere weak and hot, lithosphere broken into large fragments called plates. Plates moves around and interact with each other. The earth"s crust isn"t a tectonic plate: continental crust. Low density 2. 65g/cm3: oceanic crust. Higher density 3. 2g/cm3: oceans (the water in them) are a consequence of this. Twelve major plates: there are a bunch of micro-plates, around 37 total plates, south american. Isostasy: iso pressure, stasy the same. Picture example: cork continental crust, oak lithospheric mantle, pine oceanic crust, water asthenospheric mantle. Series of observations: south america and africa can fit together. They tell you how they were moving (glacial striations) He wasn"t considered an expert" in the field. 1960"s: research in oceans, the topography of the ocean floor. If the earth isn"t expanding, for everything created, something must be destroyed: seduction zones, trenches, earthquakes. Continental crust for the most part, cannot be destroyed. Oceanic crust: created - divergent, destroyed convergent subduction.
