Applications of Convection Volcanism

It appears that water is a necessary ingredient for plate tectonics to function. Without it the mantle is too solid to convect. The heat still needs to rise and get out...
- On Mars, mantle hot spots appear to have resulted in volcanoes in the past. (Olympus Mons)
- On Venus, it appears that the heat builds up for hundreds of millions of years, then is released by intense volcanism. The entire surface of the planet is replaced in a few million years.
- Mercury and the moon have cooled enough that heat conduction is sufficient to transport heat from the core to the surface.

It appears that water is a necessary ingredient for plate tectonics to function. Without it the mantle is too solid to convect. The heat still needs to rise and get out...