CAS ES 144 Lecture Notes - Lecture 4: Asthenosphere, Subduction, Basalt
9 Oct 2016
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Document Summary
Plate tectonics i - theory and early evidence. First brought to attention in 1596 by abraham ortelius. Same species of fern fossils on different continents (south america, south. All continents were part of one huge landmass (200 mya, pangea) and over time, they all drifted apart from one another. The edges of the continents fit together - suggested that they may have drifted from their original place. Had the wrong mechanism of explaining why that happened. Continents moved because of gravitational attraction of equator and sun/moon. Each deeper layer is heavier than the next. *density - expression of heaviness amount of mass contained in a volume. Not entirely liquid, not entirely solid; like melted wax or plastic. Higher pressure requires increased temperature to melt. Lithosphere, asthenosphere, mesosphere (in order from crust to core) Oceanic crust (thick, light, made of basalt, lighter color 2. 7 g/cm3) is denser than continental crust (thin, dense, made of granite, darker color,
