At http://phys.org/print290255566.html … water as a lubricant of Plate Tectonics may be over rated according to geoscientists in the current issue of Nature – following the examination of water in the mineral olivine. Experiments suggest the presence of water actually weakens the mechanical strength of olivine, a key component within Earth's mantle – it is thought. The result is that the role of water within Earth's interior requires a reassessment. In fact, a major reassessment as water is supposed to provide the lubrication to move continents apart. Another consensus theory with problems.