Wibble: The usual line from the YEC camp that catastrophic plate tectonics occurred during the flood when the continents shifted into today's position over a period of days or weeks does not in the slightest tally with this evidence of radiometric ages, erosion and reef structures, while it is completely in accord with the mainstream view
Logically irrelevant. You know why? because your example is one of isolated induction.
That is to say, I can take a Jack the ripper suspect, and give you what seems like a solid induction as to why only him being the ripper, can explain such evidence but really you are taking a line of evidence in isolation, and ignoring all of the other evidence which does not fit your notion. You have simply affirmed the consequent in your mind, because "if theory X evidences P is expected" you have then reversed it and concluded that because of evidence P, therefore X.
Wibble: If an island's potassium-argon age is divided by the island's distance from the hotspot it can be shown that the islands have moved at an average rate of 6.6-9.1 cms per year.
GPS can measure the rate of movement today. These measurements give a rate of about 7.9 cms per year, right in the middle of the range deduced independently from the radiometric dates
In the very same way, Humphrey's predicted rate of decay for helium was bang on balls accurate, for a young earth.
You can also expect 7.9cm a year from a flood thousands of years ago as evidence anyway, or are you saying that if there was an explosion fifteen years ago you would still expect shrapnel to be flying around at 500mph?
Wibble: This can only happen as the island slowly subsides and erodes over millions of years.
Warning signs in my mind go off when I hear people say; "this can only happen if evolution and millions of years are true", because let's face it, you have absolutely no way of knowing whether you are correct, nor can you test if you are. For all you know it has absolutely nothing to do with age.
Sure, you want to affirm-the-consequent badly, by proclaiming evidence unique only to great age, but that's just not how it works. Very seldom indeed, do the scientists that don't accept great ages, actually have problems explaining it without that age.
Essentially barrier reefs don't need millions of years, movement at 7cm a year don't need millions of years unless you assume millions of fictional years to begin with.
Your argument is basically circular, you are arguing great age, then showing the evidence you think can only point back to great age but this depends on first assuming you have all of those years for a rate of 7cm..
EXAMPLE of circular reasoning;
"This person has been walking at 2mph around the world...look, we can show that for the past three years he has done this at a 2mph rate, therefore because he claims to have travelled X amount, and this figure would fit exactly with our theory he has been walking since he was three years old, around the planet, therefore he has been walking around the planet for this long and because we believe he is actually 145 years old, then these figures all match with each other as if it was a 2mph rate then that would fit with him walking the earth for 142 years, as he admits he has done X mileage."
But this assumes that those years existed to begin with and that the rate was the same for the years they did not measure.
Think about it, it's begging-the-question because in order for your long age date to work, first you need to assume you have millions of years worth of annual 7cm rates to play with, which is actually what you are trying to prove. But equally I can argue logically thus; "if there weren't millions of years, why are they moving slowly?" Then by answer we can see that in the past the earth was one super continent, which split apart, and it makes sense that when such things happen, they happen catastrophically. It makes sense that a violent event cause the pangea to split, which is the actual cause of the movement, as well as the plate activity, not long ages. So then if the islands were already X amount apart and have been moving for most of the time since, at 7cm, then that is perfectly explainable without long age. (Do you know the original place they were, if you assume a 7cm rate? For example if you extrapolate backwards, that might fit with long ages, but what if they haven't drifted that far? Did you think to ask that question?) For example, if a car breaks down, if someone pushes it from one town to the next at a certain rate, that works only if you know they started pushing from that town, but if they drive 90% of the way, then broke down, then you don't need the hour you thought you needed.) In the same way, if they have only been drifting for a short amount because of their original location then you don't need millions of years.
So then you CONFLATE the cause, with long ages.
Another example of circular reasoning is this;
"well there is an incomplete fossil record."
"because there are no transitionals."
Because there is an incomplete record."
"why is it incomplete?"
"because there are no transitionals."
Logically it's weak evidence and a tenuous case to accept that millions of years of history exist based on a rate because the rates can change. So then you have to say that the rate an island moves, can never be beyond cm a year. Can you provide scientific evidence that physics won't allow matter to move beyond 7cm per year?