The first thing you will notice about the sea floor in the north Pacific is that it shows a long line of seamounts and islands stretching from the Kamchatka peninsula in Russia, toward the south, and then going southeast to the Hawaiian islands. These are a long chain of volcanic mountains known as the Hawaiian-Emperor seamount chain, formed from lava flows on the sea floor.
The conventional explanation for this chain of volcanoes is that there is a hotspot in the mantle which sends up heated plumes of magma in a particular location due to convection cycles in the mantle. The Pacific plate, one of several tectonic plates that together form the crust of the Earth, is moving across this hotspot, and this forms a series of volcanic mountains that may or may not reach the surface of the ocean to form an island.
This conventional explanation is a good one. The Hydroplate theory does not even have an explanation for volcanism in the middle of a plate, as far as I am aware. The Hydroplate model suggests crustal plates with water chambers underneath that broke up catastrophically during the global flood and which may have moved sideways as the water was expelled from below. In that model, volcanoes occur at the margins of plates as they collide with each other. I have yet to find any reasonable explanation within this model for the existence of the Hawaiian-Emperor chain at all. The conventional model, in contrast, does fit a number of lines of evidence and at least explains the existence of this chain.
However, there's more to this explanation. The CPT model involves rapid plate movements during the Biblical flood. In particular, at least one crustal plate subducted down into the mantle in a very short time (several weeks), setting off a catastrophic chain reaction around the globe and rapid tectonic movements that produced global flooding. The plate movements we observe today are remnants of these movements, but much slower than in the past. The conventional plate tectonics model, unlike CPT, assumes that current plate movements have been more or less constant for many millions of years at today's very slow rates.
How could we test which of these models is more explanatory? Well, here's one way of doing that. And you can do it from your home by looking at a map.
You have to understand that we can use the size of a volcanic mountain to estimate plate speed. If we assume a relatively constant rate of heated magma rising from this hotspot in the mantle, then the slower the plate moves, the more magma will accumulate in that spot. This forms a larger seamount. If magma continues to accumulate in the same spot, the seamount will reach the surface and become an island. If it continues even longer, the island will become larger and larger. If the plate is moving more rapidly, the seamounts will be smaller because lava did not have time to accumulate before that location on the plate moved away from the hotspot in the mantle. So how large these volcanic mountains are, and how far apart they are spaced, can tell us about the speed the plate was moving when they formed. There are going to be variations, but we want to look for overall trends.
We know where the hotspot is today. The largest and easternmost island of Hawaii is still experiencing lava flows today. It is still over the hotspot. If you move backwards along the volcanic chain, you are looking backwards in time. Not only do current measurements of plate movement indicate this, but radiometric dating concurs (though we can debate about the exact ages).
So let’s take a look at the chain. This is where the Google Earth link is handy because you can zoom in and rotate in order to look closer. Where the chain begins, the seamounts are all fairly small. If you compare them to the size of the largest Hawaiian island, there is a huge difference. This implies that the Pacific plate was moving much more rapidly than it does today when these sea mounts were formed. In fact, the entire chain of seamounts is much smaller than the Hawaiian islands at the end of the chain. This seems to imply rapid plate movements for most of this history, and then a profound slowing of the plate toward the end.
The most interesting feature of this entire chain is the very abrupt change of direction. The volcanoes were forming in a southward line (indicating that the plate was moving northward) and then they abruptly begin to form toward the east and only a little south. It's a very distinct inflection point. The seamounts immediately get smaller at the same time the direction changes. Not only are these first eastward seamounts smaller, but they are farther apart. All of these indicate an increase in speed. This tells us there was an impact on the east side of the Pacific plate that accelerated it toward the west. The plate increased speed and changed direction due to this impact. The plate which impacted the Pacific plate must have been the North American plate. So we can see evidence, in the seamounts, that the North American plate has crashed into the Pacific plate and altered both its speed and direction.
As you go from west to east (i.e. forward in time) after this impact, the seamounts grow gradually larger and closer together and then, as the speed of the Pacific plate drops off considerably, they begin to form islands. The islands grow larger and larger until you reach the largest island of all where there are still active volcanoes and slow plate movements and you have caught up to the present day. But this chain of volcanoes tells a story of much faster plate movements in the past.
Notice that I told you this assumes a constant rate of magma rising from the mantle hotspot. We can examine our assumption here. Is it reasonable? There are only three options: Either the hotspot is growing hotter, it is growing colder, or it is staying the same. If the hotspot is staying the same, we naturally come to the conclusion that the Pacific plate was moving much faster in the past and is now moving much slower. If the hotspot is growing colder over time, then the deceleration is even greater. If the Hawaiian islands are successively larger and larger even though the hotspot is now cooler than it was, then the speed in the past was even greater and it has slowed even more than we expect from a model in which the hotspot has remained unchanged.
The other possibility is that the hotspot is growing hotter and thus sending up more and more magma over time. This would make it possible for the plate movements to have been very slow the whole time. This is essentially the mainstream view. If the plate has been moving at a constant slow rate, then we would explain the increasing size of the islands by appealing to increasing temperature in the mantle hotspot. But that has a problem of its own. If the hotspot is growing hotter, what is causing that? And should we be concerned that it appears to be growing so much hotter than it used to be? In any event, it does not appear that these processes have always been occurring at a constant rate. Either the plate has slowed considerably or the hotspot has grown much hotter. I find the former much more reasonable for several reasons.
In this one volcanic chain, we have evidence, not only that the crustal plates are moving, but that they moved much faster in the past. But there’s more. We saw that the North American plate crashed into the Pacific plate and changed its speed and direction. This affects not just the Pacific plate, but the North American plate as well. This is most likely the impact that pushed up the Rocky Mountains. Conservation of momentum says that if the Pacific plate accelerated rapidly due to this impact, then the North American plate must have decelerated rapidly. This abrupt stop would crumple the North American plate along its western side. Not surprisingly, there’s a mountain range there.
These features are a lot easier to explain in terms of acceleration and deceleration of plates than if they were the result of slow, gradual processes with unvarying rates. This is just one piece of the puzzle for the CPT model. Yet it forms a handy side-by-side comparison of the competing models.
The explanation commonly offered by mainstream geology for the larger size of the Hawaiian islands compared to the older seamounts is that the older mountains have shrunk over time due to erosion and subsidence. This explanation fails on multiple points.
1) There's no experimental evidence for this explanation, as far as I know. It is just thrown out there as a possibility.
2) It doesn't make sense of the similarity in size of most of the chain of seamounts. Do they shrink until they reach a certain size and then stay the same forever? Subsidence and erosion might be a potential explanation if we had a nice gradual increase in size all along the chain. Instead, we have what is supposedly tens of millions of years of seamounts that are roughly the same size, then a fairly rapid transition to much larger islands. The older north-south section is not significantly smaller than the younger east-west section.
3) The greatest erosion should take place on islands, not seamounts. Erosion forces should be stronger for the land above the water due to wind and rain and wave action. Once an island drops beneath the waves, that should slow its shrinking considerably. This should, again, result in a more even chain. That's not what we observe.
4) If we're suggesting that all of the islands and seamounts in the Hawaiian-Emperor chain were originally of similar size and some merely shrank due to erosion and subsidence, that simply doesn't work. If you take any of the Hawaiian islands, its footprint would cover several of the smaller seamounts in the chain. If the small volcanoes were widely spaced, it might make sense to suggest they had once been sizeable islands. But most of them could not have been that large initially because they are too closely spaced. A large mountain doesn't erode away into several small mountains. Subsidence might work if a tall mountain with several peaks sank until it appeared to be several smaller mountains, but it really doesn't look like that happened. Especially for the smaller seamounts, the ocean floor around them does not show signs of a larger mountain sinking. It appears relatively flat and undisturbed.
5) The older seamounts are not all that eroded. They're not gently sloping and rounded off. They don't appear to be the small remnants of eroded islands, in other words.
6) The erosion/subsidence hypothesis still doesn't account for the sharp change in direction or the drop in seamount size and increase in spacing afterward. The CPT theory accounts for all these facts at once.
Because of these lines of evidence, the Catastrophic Plate Tectonics theory has more explanatory power than either the mainstream Gradual Plate Tectonics view or the Hydroplate Theory, at least when it comes to explaining the Hawaiian-Emperor volcanoes. This is just one way of comparing and testing models. Creation science actually does offer testable models that hold up to scrutiny.
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