Unformatted text preview: n takes place as diffusion creep, or
dislocation power-law creep, mobility is highly temperature
dependant, and has a quantum mechanical probability
A few hundred degrees temperature change results in many
orders of magnitude viscosity change.
How does this change the picture? This effect means that the upper boundary layer is also
mechanically stronger (a plate), and serves to further cap
temperature loss, increasing the tendency of cold
downwellings to dominate the system, and reducing the
upwellings (Davies and Richards, 1992).
upwellings OCE 661 If the viscosity change is too great, the plates will form a
stagnant “lid”, and convection will go on below, perhaps this is
happening on Mars and or Venus?? What is this?
OCE 661 The Earth is also round, more or less, what effect does this
have? Convection becomes more complex, but the main
difference is that the symmetry of upper and boundary layers
is again broken. Why?
is The surface area of the CMB is much less than the area
of the Earths surface, so for ther...
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- Winter '14
- Plate Tectonics, Atlantic Ocean, Mantle, Alfred Wegener, Richards