Catastrophic plate tectonics
Catastrophic plate tectonics is a bit of creationist junk which claims that:
- "Plate tectonics occurred, but catastrophically. Slabs of oceanic crust broke loose and subducted along continental margins. This lowered the viscosity of the mantle, leading to meters-per-second runaway subduction. The earth's magnetic field rapidly reversed several times. Steam caused a global rain. Flood basalts erupted. The lighter mantle material of the new ocean floors made them rise, causing the oceans to flood the continents. The flood carried and redistributed sediments. The process slowed almost to a stop when nearly all the old ocean floor had been subducted. Subsequent cooling of the ocean basins caused them to sink to where they are today."
This claim is utterly worthless.
 Physically impossible
Magnetic fields can, in some conditions, heat water. Magnetic resonance effects can dissipate as heat - but this effect is tiny and can barely be detected. If the effect wasn't minuscule, power line transformers would flash boil and steam everything around them every time it rained - not to mention pumping out heat into the surrounding water vapour in the air. The heating effect is also be relative to magnetic field strength, and even in the strongest magnetic fields the energy delivered is negligible. In terms of magnetic field strength (measured in Teslas, T) loudspeakers generate fields of 1 - 2.4T, MRI instruments generate fields up to 9T in strength (and don't flash boil the water in the human body). The Earth's magnetic field, by comparison, is thousands of times weaker than this on the order of 58 µT (5.8×10−5 T) at most. Reversing the magnetic field of the Earth, as described in the creationist theory, cannot deliver that sort of energy to the water.
"Lighter mantle material" rising up is completely insane. One would need something heavier to take its place for it to rise instead of a complete vacuum. In Earth's molten infancy all the lighter material have already risen to the top, resulting in the continents. This is to say nothing for all the water that would have flash boiled from the ocean floors as they grew molten and rose, killing anything living.
The only real scientific theory that details anything like this is a theory based on a global resurfacing event on Venus. Venus has no water present as Earth does to lubricate the motion between tectonic plates (studies suggest that Venus lacks an asthenosphere for subduction). It is theorized that the mantle builds up heat from radioactive decay till it is hot enough to melt the rocks on the crust. This lasts till the entire surface is covered in new rock. This is only a proposal, as it really has no firm ground to stand on till scientists can get their hands on rocks from Venus's surface.
Part of the theory is that due to the high ratio of deuterium to hydrogen in the atmosphere that there was water in the atmosphere of Venus at one time. When this happened the intense heat forced a good deal of lighter hydrogen out of the atmosphere, while the rest of the oxygen/hydrogen to combined with sulfur from volcanism to form the sulfuric acid (H2SO4) that is a component of the atmosphere today. The theory would also explain why Venus has no real magnetic field to speak of, as it has a very slowly rotating dynamo core (243 days). These explain if catastrophic plate tectonics did (or could) happen, there would be no water on, or a magnetic field around, Earth.