Plate tectonics occurred catastrophically and has since slowed (Talk.Origins)

Claim CD750:

Creationary claim:
 * 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.

Source: Austin, S. A., J. R. Baumgardner, D. R. Humphreys, A. A. Snelling, L. Vardiman and K. P. Wise, 1994. Catastrophic plate tectonics: A global flood model of earth history. Proceedings of the third international conference on creationism. Pittsburgh, PA: Creation Science Fellowship, Inc., pp. 609-621.

Talk Origins position:

Much geological evidence is incompatible with catastrophic plate tectonics:
 * Island chains, such as the Hawaiian islands, indicate that the ocean floor moved slowly over erupting "hot spots." Radiometric dating and relative amounts of erosion both indicate that the older islands are very much older, not close to the same age as catastrophic tectonics would require.
 * Catastrophic plate tectonics says that all ocean floor should be essentially the same age. But both radiometric dating and amounts of sedimentation indicate that the age changes gradually, from brand new to tens of millions of years old.
 * As sea-floor basalt cools, it becomes denser and sinks. The elevation of sea floors is consistent with cooling appropriate for its age, assuming gradual spreading.
 * Guyots are flat-topped underwater mountains. The tops were eroded flat from a long time at the ocean surface, and they sank with the sea floor. Catastrophic tectonics does not allow enough time for the sea mountain to form, erode, and sink.
 * Runaway subduction does not account for continent-continent collisions, such as between India and the Eurasian plate.

Catastrophic plate tectonics has no plausible mechanism. In particular, the greatly lowered viscosity of the mantle, the rapid magnetic reversals, and the sudden cooling of the ocean floor afterwards cannot be explained under conventional physics.

Conventional plate tectonics accounts for the evidence already and does a much better job of it. It explains innumerable details that catastrophic plate tectonics cannot, such as why there is gold in California, silver in Nevada, salt flats in Utah, and coal in Pennsylvania (McPhee 1998). It requires no extraordinary mechanisms to do so. Catastrophic plate tectonics would be a giant step backwards in the progress of science.

CreationWiki response:

It does appear that there is very little solid evidence that the Mid-Atlantic Ridge is still spreading. Although evolutionists may claim otherwise, so far they have not come up with very convincing arguments -- and many of the arguments that they do come up with are either contradictory or highly subjective (e.g. radiometric dating of ocean bottom sediments).

According to the University of California, Berkeley, scientists can now recognize that plate tectonics did not exist in Earth's ancient past. However, because of their faith in radiometric dating, they do not believe this could have applied thousands of years ago, only billions.

"Yet geologists today also know that some of the factors that changed the Earth in the past cannot be seen at work today. For example, the early Earth was pummeled by gigantic hunks of solar debris, some as big as Mars. For the first one or two billion years of Earth's history, plate tectonics didn't even exist as we know it today."

Scientists still do not even understand what makes Plate Tectonics work.

Related References
Continental Drift