Geomagnetism and the rate of Sea-floor Spreading

"What I'd like to know is where the timeline on the graph TC keeps posting comes form and how it was derived.Was it simply based on assuming a constant rate of spreading and calculating from that ? Because if not, TC has a lot more explaining to do."
--The rate of spreading was not a required consideration for the geomagnetic data. It was derived by plotting the quantity of geomagnetic reversals occuring with each successive 3 My span of time since ~170 Ma. The source of the data can be found in the rough preliminary copy of my article, link in post #1.

"The most relevant graph is the 2nd one in Message 31 (the first one is an empty white square for me)."
--The first displays as an empty white square for me as well. Have you tried clicking the link right above it? If it still doesn't display you may need Macromedia flash player. http://www.macromedia.com"This graph shows the rate of sea-floor spreading as inversely proportional to the rate of magnetic reversals. In other words, it shows sea-floor spreading slowing down as magnetic reversals speed up, and vice versa."
--Well, actually it is proportional to the width of the polarity chron, not the slowing down or speeding up of magnetic reversals."He has no data for the sea-floor spreading rate to correlate with his graph¹, and the right axis is unscaled anyway²."
-[1] - Thats because it isn't needed. I am not trying to say that the data show that the rate sea-floor spreading was such, but merely that the geomagnetic data can be interpreted this way.
-[2] - The inferred rate of sea-floor spreading is relative."Why TC is so hot on this graph is difficult to understand, because it shows the exact opposite of what TC actually believes. TC believes that the rates are positively, not inversely, correlated. TC needs a graph that instead shows their rates increasing and decreasing in concert. This is the only way his scenario can produce the observed magnetic striping data on the sea-floor. In other words, not only is his graph unsupported by any actual data, it contradicts his position anyway."
--You have a misunderstanding of what the graph represents. As I have explained, the more geomagnetic reversals in a certain span of time, the slower the implied rate of sea-floor spreading, as with the inverse. If the rate of sea-floor spreading was higher than usual, a polarity chron would be thicker.

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"In fact, you are exhibiting an EXTREME version of uniformitarianism in insisting that there is some predictability to the reversals in the geological record. Very silly."

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--If geomagnetic reversals were predictable... I could give you those numbers and calculations you want. They are not predictable and are random, therefore, I can't give you those numbers.. it is merely relative.

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Then explain to us how you can use them to measure the rate of plate divergence? If my stopwatch ticked seconds of at random intervals, it would be impossible to time a race. And yet you seem to say that it can be done.

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"What is an independent line of evidence to support CPT?"

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--If the frequency of geomagnetic reversals over time can plausibly be attributed to the rate of sea-floor spreading, this is an evidence for CPT.

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No. I am talking about independent geological evidence to support your fantasy of CPT based on magnetic reversals. In other words ask this question: "What would I expect to see in the geologic record if CPT, based on mag reversals, were true?" If you don't answer this question, you are not doing science.

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This randomicity is not observed in the data.

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Wait, you just said that the reversals occur at random intervals...

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It is thus due to either the rate of sea-floor spreading, or a change in the frequency of geomagnetic reversals over time...

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Or both. I'm certain that the reversals change frequency over time and there appears to be a pattern. However, I can use radiometric dating to support this. What do you have? The point is that if the intervals are erratic, you cannot directly measure plate vectors. These vectors are time related and you have no reliable time function in your scenario. Your analysis is ill-conceived and incomplete. You cannot measure a rate with a clock that does not keep time.It is clear from conventional geology that, indeed, the Cretaceous was a period of rare magnetic reversals and higher plate velocities. But we figured this out using radiometric dating and basic geological principles. It all comes together. But the rates are nothing like what you come up with (if you did come up with a rate) for CPT. You as simply whistling in the darkness of ignored evidence.

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...(which would be cyclic as far as the data suggest).

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Cyclic, but not periodic.

You're not answering the question. How were the dates worked out ?
You need dates for the magnetic reversals to produce that graph. So where did those dates come from ?And if the dates AREN'T based on assuming a constant rate of spreading, then explaining the data is not so simple as assuming an increased rate of spreading. The dates need to be explained as well.

You are attempting to compartmentalize consideration of your proposals into narrow areas in order to make the conflicts and contradictions between them less apparent. Perhaps to you, but from here it is apparent that you're simply trying to avoid the more ridiculous implications. And in any event, you have no evidence supporting either one. As you well know, this is a Creationist idea that I was merely repeating for your benefit. That physical laws could ever have been different would never have occurred to me. I wonder if it wouldn't be too much to ask if you would stop repeating this since, as I have pointed out several times now, it is incorrect. I said your ideas come from Genesis, not from evidence. You denied it in one post, then when challenged conceded it in the next. I was merely calling attention to your flip-flop.Moving on, I don't think you have sufficiently justified this change in your graph. You need to describe how you derived the red line for the rate of sea-floor spreading. Here's the graph as you presented it in Message 1:And here is the graph as you presented it in Message 31:In your descriptions you claim to be correlating the rate of sea-floor spreading with chron duration, but your graph doesn't show chron duration. It instead shows the rate of magnetic reversals. It is of course true that, to state this approximately, average chron width is an inverse function of the average rate of magnetic reversals, so this isn't a serious deficiency.One piece of relevant information that is missing is the actual width of magnetic stripes on the sea floor. Assuming that sea-floor spreading rates were not dramatically different in the past, the width of magnetic stripes should increase with increasing chron duration. A table of the widths of magnetic stripes on the sea floor versus time would be interesting data to have if you've come across it.It is true that wider magnetic stripes could be equally well explained both by longer magnetic reversal periods and by increased sea-floor spreading rates, but the latter only if you ignore the radiometric data. And it was Edge's introduction of the radiometric argument that initiated your attempts to exclude it from the discussion by claiming it was really only part of "CPT in general", which is where this message began.--Percy [Clarified final paragraph. --Percy][This message has been edited by Percipient, 08-19-2003]

It's been a few days since I reviewed this entire topic, so I'm really hazy about what's been said so far.I'm assuming that TC's graph (above) is a good approximation of scientific reality. I just have some comments.I strongly suspect that the dating of the magnetic reversals was done on the continents, and then applied to the ocean basin. That is, the most recent magnetic polarity is found at the mid-ocean ridge, and the reversals were counted out, and dated relative to that.I also strongly suspect that the ages of the oceanic crust, and by extension, the spreading rates, were dated by magnetic reversal correlation (see previous paragraph).I note that the time frame of the highest spreading rates correlates with the Cretaceous geologic period, the period of the most recent great transgression of the sea up onto the continents.As an aside, it is interesting that there seems to be an inverse relationship between magnetic reversal rates and spreading rates.All in all, TC's data seems to be a nice, interesting chunk of mainstream science. That is, I have no idea of how he finds it to support catastrophic plate tectonics.Well, it was a quickie - I gotta get to bed.Moose

As I understand it, TC is saying that instead of interpreting the data as showing variations in the rate at which geomagnetic reversals occur it should be interpreted as variations in spreading rate.This only works if the timeline on the graph is derived from the measured widths using an assumed spreading rate. Even if the spreading rate is assumed to vary there is a complication. Unless TC managed to totally misunderstand my question (and I have no idea how he can have construed it to give the answer he did) it is clear that in fact the dating information comes from some other source he declines to mention, and therefore his argument - in its current state - fails to address the data he is using.The other half of his argument is an argument from personal incredulity against the conventional view. It can't carry any weight of the evidence really does support conventional plate tectonics as seems to be the case.

I haven't checked his numbers regarding when magnetic reversals occurred, but they aren't inconsistent with what I already know, such as that there were no magnetic reversals for a long time around a hundred million years ago, so until some problem pops up putting them in question I'm inclined to accept them at this point in time.But TC has no data for the red line, the sea-floor spreading rate, and so it is very unlikely to correspond to reality. He simply created the line to clarify his argument that it might not have been the rate of magnetic reversals that changed but instead the sea-floor spreading rate. This is, of course, contradicted by the radiometric data.So, anyway, when you go on to say this: You have to realize that TC's red line is simply the inverse of the magnetic reversal rate (except where the rate goes to 0, so TC has fudged the line). Since it doesn't correspond to real data, there was no "counting out" from the mid-ocean ridge.--Percy

While my method for interpreting the rate of seafloor spreading from the geomagnetic data were not flawed in and of themselves, I am now convinced (from independent study) that the geomagnetic polarity time scale is not directly representative of the rate of seafloor spreading. Certain aspects of geomagnetic data could very well be used as good source for CPT research regarding the question of spreading rate (such as the Cretaceous thermal event and the cretaceous superchron), albeit direct derivation of relative spreading rates from the systematic change in reversal frequency throughout the GPTS doesn't seem plausible.Since no one in this thread probably has not read glatzermier's papers I have been citing, I encourage the read.As opposed to the frequency of geomagnetic reversals being indicative of spreading rate, it seems it does indeed reflect the thermal evolution of the CMB, probably due to a combination of geodynamic processes during CPT.If there are still questions, don't hesitate.

Do you intend to explain where the timeline on your graph came from ?I ask because if you dodge a simple question about your own data - as it appears you have - then it is clear that there is no point asking questions of you at all.

"Do you intend to explain where the timeline on your graph came from ?"
--Yes, it is from data published here:Harland et al., A geologic Time Scale 1989, 1990.If you have trouble locating this resource and still would like the data, I could either type it up for you or give you several second-hand references. There have also been advancements in our understanding of the geomagnetic record during the 'Jurrassic Quite Interval' so you may want to keep that in mind if you want to look into the geomagnetic polarity timescale more rigorously."I ask because if you dodge a simple question about your own data - as it appears you have - then it is clear that there is no point asking questions of you at all."
--No dodging here. I just didn't want to waist time giving information that no one would pay any attention to given my turning of the tide.--Edit, the data was originally obtained by assessing magnetostratigraphy and dates given to the various polarity chrons on land (by radioisotopic methods).[This message has been edited by TrueCreation, 09-19-2003]

There was a reference to an article posted elsewhere, the pizza will be ready before I find it but the basic idea is this:1) magnetic reversals are noted around the spreading centres
2) the dates of these reversals are measure in rocks on land
3) other independent cycles that leave traces are also used to date the reversals
4) the above two dates agree reasonably well
5) the dates of reversals are used to calculate long term average sea floor spreading rates
6) those rates agree with directly measured rates that exist todayI think if you use those rates and dates (but I don't know this for sure) they also line up with other evidence for the start of continental separation.I'll see if I can find the post that contains that reference later and edit it in.I think this is the post but don't have time to check
EvC Forum: S.America and Africa's rate of spreading[This message has been edited by NosyNed, 09-19-2003]

For the benefit of those of us just not up to the rigours of translating TC-ese at this time on a Friday night, could someone tell me if TC is conceding, dodging or reemphasizing? I just can't tell.--Percy

"For the benefit of those of us just not up to the rigours of translating TC-ese at this time on a Friday night, could someone tell me if TC is conceding, dodging or reemphasizing? I just can't tell."
--Basically I said that my speculation that we can infer the rate of seafloor spreading from geomagnetic data was wrong. I came to this conclusion during my absence since I last posted in this thread (through independent studies).I also noted that while we may not be able to infer spreading rate from the geomagnetic data, we can still learn much about past geodynamic events and processes from its analysis. The changing frequency of geomagnetic reversals, for instance, may be explained by pieces of oceanic lithosphere sinking down to the CMB during CPT.I hope this post is less nebulous than my last one. I am tired and Saturday night is probably the only night I get some good sleep and so I am way over due..

Nosyned, you wouldn't happen to have done any research on your #3. I think that is the only one in that list which could potentially be detrimental to the CPT hypothesis.