Scientists had noted for hundreds of years that the shapes of the continents, in particular those on either side of the Atlantic Ocean are such that they look like they could fit together.
Most creation scientists agree that the continents were probably once together, for the most part, in a super-continent based on Genesis 1:9.
Moreover, rocks and fossils found on the facing shores of the different continents were remarkably similar. We now understand this, not just theoretically, but experimentally, by recognizing that the continents are indeed drifting apart. Using satellite data we can measure that South America and Africa are moving apart at an average rate of 5.7 centimeters per year, about the same rate at which your fingernails grow. This spreading apart of the continents is now understood because material is measured to be moving up to the surface from deep in the earth at the mid-ocean ridges. Our understanding of the Earth’s dynamics is completely consistent with this observation,
He makes a good point here in showing that we know the continental plates are drifting apart because we can observe them drifting. Since this is an observation that can be made in the present, this falls under operational science. And, of course, creationists agree with these observable facts. However, it is when scientists make assumptions about the past (which cannot be observed) that we disagree.
and using the present observed rate of ocean spreading we can determine that the observed continents were part of a single land mass about 250 million years ago.
Herein lies the assumption and problem with which creationists disagree. Many secular scientists assume uniformitarianism (i.e. the idea that the rate at which an event happens in the present is the same as it was in the past) and extrapolate backwards. Hence, they automatically reject catastrophes when dealing with the past in many areas, such as this one!
It is commonly assumed that this average rate we observe today of 5.7 cm per year has always been the rate at which the continents have drifted apart. One must ask “how do they know that the rate has always been the same?” What source of information are they using that allows and confirms this assumption they are making? But that’s the problem, there is no source of information that confirms this assumption. To state that the rate has never changed in the past means one is omniscient and omnipresent (which are qualities of God).
This would be like seeing a 52-gallon bathtub full of water and noticing the water coming out of the faucet at a rate of 5.7 ounces per minute and then assuming that this was always the rate and that it must have taken 19.5 hours for the bathtub to fill up. However, what is the source being used to make such an assumption? None: it is assumed without any evidence or source of information. Someone could have very easily filled the bathtub in five minutes and then turned down the faucet.
Creationists have several ideas about the breakup of the continents and the catastrophic Flood in Noah’s day is the mechanism for such rapid movements. For some helpful articles, please see Plate Tectonics.