GLG 301 Lecture 28: GLG301-2017-Summary 28
Document Summary
I have kept the entire long version of the driving forces lecture that i only presented in abbreviated form on april 27. Parts shaded in grey were not really covered. The discussion of what drives plates is highly controversial. In the following i have not kept strictly pure to one set of models, thus there is some mixing of. Apples and oranges to keep the discussion simple. Mechanisms to move continents: 19th century. Explosive forces blasted continents apart: late 19th to early 20th century. Basically centrifugal forces: other ideas through the late-20th century have included contracting and expanding earth models, but these are hard to take seriously. In the mid-1920s, it was realized that radioactive decay inside the mantle releases heat. This heat must be convectively transferred to the near surface and radiated into space: start of convection is controlled by the rayleigh number. R = gd4/k ratio of driving buoyancy to resistive viscosity and thermal diffusion.
