Plate Techtonics!

[Nyril]

Several years ago (more then one, less then ten thousand) the idea that the Earth was not the center of the Universe was high in the ranks of things we argued about. Neatly behind that would be the age of the Universe, age of the Earth, the Earth goes around the sun, Earth is flat, etc. In time, a number of these ideas were accepted by pretty much everyone. By that I mean that I doubt even YEC will argue the point that the Earth is the center of the Universe and in addition to being flat also has the sun and everything else revolve around it.

On that line of thinking, I'd like to ask what you think of plate tectonics in that regard. It isn't brought up much on these boards, but because it neatly explains how we get fossils and strata on opposite sides of the Ocean all neatly lined up (such as the shore between Africa and South America), I imagine there must be some controversy surrounding it.

So, plate tectonics, is it like the Earth being round, or closer to evolution in terms of the amount of public debate surrounding it?

[otseng]

But, the problem with plate tectonics is that it doesn't explain why this change occurred. Why would it move due west to its current position, then "abruptly" change?

I'll phrase it in a really dumb way: why not? The image I have in mind is of the plate tootling along, and then bumping into something and bouncing, much like a billiard ball. Unfortunately, this doesn't quite explain things, since there isn't an obvious candidate for what it would bump into.

Actually, I would agree. It would appear that if North America moved due west in the past, then in its current location it altered its course, then it did somehow "bump" into something. But, like you state, what did it bump into? And why does South America, Europe, and Africa also experience this "bumping"? Also, why does this bumping happen "now"? Why did it not appear to happen in the past?

By analogy, I think of a pot of water being heated. If it's in a glass vessel, like a beaker, then we can see the convection currents from the schlieren lines (little lines from changes in refractive index of the water, resulting from different densities of hot and cold water). The currents do a general up-here-then-down-there kind of motion, but the location and direction of the currents can change. It's pretty much a chaotic system, with no hard and fast rules about where the currents have to form.

The same basic rules are likely to apply to the mantle, but with the proviso that we know very much less about the mantle than we'd like to. Are there significant inhomogeneties in it? Probably. Do the convection currents stay put? Probably not. If convection currents influence the plates, do the plates influence the convection currents? Probably, but exactly how I don't know.

This is one of my main problems with mantle convection. As you state in your pot of water example, it should be a chaotic system. But crust movement relies upon a non-chaotic system. That is, all convection cycles should remain in the exact same place for not just one hour, or one month, or even one year, but millions of years. How can this happen?

My understanding is that it is due to changes in the earth's magnetic field--indeed reversals of polarity. I have no clue how this happens, but then, I'm a geneticist not a geologist.

I'll reserve detailed comments on magnetic anomalies until someone can present a global map of anomalies.

But, a complete reversal of the polarity of earth's magnetic field is extremely hard for me to believe. What is the mechanism? How does it happen? Are there measurements of the magnetic field that indicate that the earth's magnetic field is reversing in polarity?

The first panel shows the declination (which isn't very useful), and the second shows the inclination (which is used to recognize normal and reversed polarities). Positive inclinations are normal, negative inclinations are reversed. You can see that polarity of Earth's magnetic field changed several times while these sediments were being deposited. Measuring the remnant magnetization of sediments and looking at the record of polarity changes they record is called magnetostratigraphy.

From the data in the declination graph, it would appear that sediments randomly points to different magnetic directions. Shouldn't it have some clear pattern to it? Also, couldn't the pattern in the inclination be interpreted that the top portion was simply displaced at an angle?

[Chem]

An explanation of the generation of the Earth's magnetic field and reversal of it is given here:

http://www.psc.edu/science/Glatzmaier/glatzmaier.html. Or
http://news.nationalgeographic.com/news ... _flip.html.

Enjoy!

[otseng]

An explanation of the generation of the Earth's magnetic field and reversal of it is given here:

http://www.psc.edu/science/Glatzmaier/glatzmaier.html. Or
http://news.nationalgeographic.com/news ... _flip.html.

Enjoy!

Actually, these articles do little explaining. They simply present what happened in a supercomputer simulation based on dynamo theory (which we're not even sure if that is happening inside the earth).

One particular set of images is interesting.

Top: A computer simulation of Earth's magnetic field structure. Bottom: An image of what Earth's magnetic field might look like during a reversal, which some scientists believe the field is headed toward.
I cannot see how the bottom picture can happen in real life. To have such a scrambled magnetic field occur does not compute in the mind of this Electrical Engineer.

What we do know about the earth's magnetic field is that its intensity has been decreasing. Ever since the 1830's, we know through direct measurement of the magnetic field that the intensity of the field has decreased about 10%. Or annualized, that means it has been decreasing at around 0.07 percent per year. A decreasing intensity does not necessarily lead to a complete polarity reversal. If I hook up an electromagnet to a battery, the magnetic field will decrease over time. But, that does not mean it is necessarily oscillating.

A complete polarity reversal would present many questions. Where is the energy coming from to increase the magnetic field? Why is it oscillating? Has the magnetic field intensity ever been zero? Would not magnetic polarity reversals screw up migratory animals? How can they adapt to such changes?

[Jose]

Thanks for the links, Chem!

Actually, I would agree. It would appear that if North America moved due west in the past, then in its current location it altered its course, then it did somehow "bump" into something. But, like you state, what did it bump into? And why does South America, Europe, and Africa also experience this "bumping"? Also, why does this bumping happen "now"? Why did it not appear to happen in the past?

It may be as simple as any plate bumping into another plate causing an effect on the trajectory of both plates. Only if their force of movement is great enough, perhaps, do they crash into each other and build Himalayas. They are all rubbing up against other plates, with forces acting on them from all sides, as well as the mantle convection forces below them. It's undoubtedly much more complicated than any of the simplified descriptions we've given here.

Why now? Probably, it has been much like this as long as mantle convection and plate movements have been going on. It's a little tricky to determine the exact trajectories of the continents in the distant past, because the most recent records (seafloor magnetic anomalies) aren't all that old. They can help us think about the current trajectories and allow us to see that current movements may not match movements of several million years ago, but they don't go back into the Paleozoic.

I'll also refer to a prior post, concerning the Emperor's Seamount/Hawaiian Island chain, which records a very clear change in direction in the past. That is, changes in direction aren't just "now"--and are recognizable if we have the right "markers."

This is one of my main problems with mantle convection. As you state in your pot of water example, it should be a chaotic system. But crust movement relies upon a non-chaotic system. That is, all convection cycles should remain in the exact same place for not just one hour, or one month, or even one year, but millions of years. How can this happen?

I think the best answer is in the second of Chem's links (I think it was the second), mentioning a mantle disturbance that's moving slowly toward the east coast. It's moving, but not very fast. Still, as you say, its movement can be measured in decades, not millenia. I don't know if this is a magnetic storm, or actual movement of the mantle material itself. If it's only magnetic, it doesn't tell us much about the speed of movement of the actual stuff itself.

The pot of water analogy is adequate for conveying the image, but not the speed. I usually like to think of a pot of oatmeal with a scum on it, in which convection will be much slower. I can't even conceive of how slow the movement would be for molten rock at ridiculously high pressures in the earth's interior. While common sense, based on personal experience with boiling water, may suggest that convection should be rapid, I think that here, we have to look for data that can inform us about this other convection system that is wildly different from things we actually can experience.

That's one of the tricky parts about science--so many things happen on a scale that is too slow, or too fast, or too small, or too big for us to have any way to relate to it personally. We have to build models (and see them as "mental movies") to get a handle on it. All too often, the data force us to conclude that the way things really work is just plain different from the conceptions we've built from our own experience. This is one of the hardest parts of teaching science--our personal pre-conceptions are often so deep and so comfortable that we have difficultry replacing them with the scientifically-accurate version. A great example of this is shown in A Private Universe (see also here), a video that starts with interviews of Harvard graduates, who wrongly answer the question of what causes the seasons--despite having been "taught" how this works, they have clung to their personal pre-conception that it's summer when the earth is closer to the sun.

'll reserve detailed comments on magnetic anomalies until someone can present a global map of anomalies.

Since we haven't been able to find a global map, I think you'll have to work from what we've already brought to the table. Those images are part of the world-wide data, for which you can correlate their information with the relevant regions of the maps of the plates and the earthquake zones. I will also note that I ran across a paper talking about starting to collect data from the Indian Ocean--which suggests that we don't have complete world-wide data yet. Nonetheless, the principles are demonstrated by the ata that we have been able to find in map-form.

But, a complete reversal of the polarity of earth's magnetic field is extremely hard for me to believe. What is the mechanism? How does it happen? Are there measurements of the magnetic field that indicate that the earth's magnetic field is reversing in polarity?

Chem's links should help here with the mechanism. So far, we've got models that seem to work. There are probably imperfections, and the models will get better as we get more data. It's not really fair to dismiss them as mere supercomputer stuff, though we all admit the GIGO rule, and there could be incorrect information as part of the input.

In the meantime, the measurements that demonstrate the past reversals are the magnetic anomalies themselves. This is one of those things that doesn't match common sense--but for which we have a whole bunch of observations that we have to link together in some kind of understanding. We've got the movements of the continents, the spreading centers with symmetrical magnetic anomalies about them, the subduction/orogeny zones, the "fits" of the continents that happen to match the back-calculation of continental movements, the fossil assemblage data that link continental regions that are now distant, but that the back-calculation places together at the time those plants and animals lived, and the current world distribution of plants and animals whose degree of difference or similarity matches the time period since their respective continents separated.

This is a lot of data. It's possible to develop two models to understand it. The first is plate tectonics, complete with the polarity reversals, and the full evolutionary theory. This model accepts things we see today, and merely proposes that these things happened yesterday, the day before, last year, a thousand years ago, October 4004 BC, 100,000 years ago, and millenia ago. There is no data to tell us otherwise. The other model proposes that god created everything exactly as it is, with all of the things in place to make it look like the other model is correct. For all we can tell, he did this just ten minutes ago, and gave us memories that make us think we've been having this conversation for longer than that--but we can't tell, because he's really good at it.

A complete polarity reversal would present many questions. Where is the energy coming from to increase the magnetic field? Why is it oscillating? Has the magnetic field intensity ever been zero? Would not magnetic polarity reversals screw up migratory animals? How can they adapt to such changes?

The first of these questions are the kinds that should be asked, and that the supercomputer modelers are trying to get at. They can't very well go visit the mantle; it's a bit toasty there. It's an important point, though, that this is the nature of science. We observe these magnetic anomalies. We have a model to explain them. We don't seem to have any other good explanation, but the model we do have raises lots and lots of questions. Usually, most good models do that--they answer prior conundrums, but pose a zillion more questions.

The latter questions are biological, and relate to the surface world that we can get to, so they're answerable. Yes, it would screw up migratory patterns. Animals use a combination of light and the declination of the magnetic field for navigation. Their compasses would get mixed up.

How would they adapt? In the Conversational English version of the term "adapt," there are two possibilities. A. They wouldn't, if they don't have flexibility built into their compasses. B. They'd learn from passing the wrong landmarks, and reset their compasses. Actually, I have no idea if this is possible. Until we have a magnetic reversal, we can't do the experiment to find out.

In the biological definition of "adapt," the answer is easier. Those individual animals that go the wrong way (possibility A above) wouldn't survive the winter, or wouldn't find their nesting sites, or whatever, and would die out. Those individuals that, for whatever reason, end up where they can survive the winter or find mates and nest sites, will have offspring. The subsequent population, if there is one, will be from the individuals that made it through. If none made it, then that species goes extinct. Adaptation, in the evolutionary sense, is a result of reproductive success of the individuals whose genetic makeup enables them to survive and reproduce, coupled with the lack of success of those whose genetic makeup makes them unable to cope. In times of a changing environment, it's pretty common for the "normal" ones to die out, and occasional "weirdos" to make it through. In this case, the "weirdos" would be the ones that weren't so good and finding their way home.

[ST88]

Would not magnetic polarity reversals screw up migratory animals? How can they adapt to such changes?

This may be a bit off-topic, but I think it would be good to clear up this misconception. Birds and other migratory creatures with magnetic material in their brains don't have a simple internal compass arrow that points in a certain direction, telling them to "go that way." Rather, the prevailing theory is that they somehow "remember" the magnetic pattern of each migratory location -- or the pathway to those locations -- from the last time they were there, also known as a magnetic map. That is to say that the direction the birds travel is not an instinct, but is learned behavior. The instinct is to "listen to" the pattern of external cues: magnetic fields, landmarks, position of the stars, and whatever the other birds are doing. So an alteration of the earth's magnetic field would not pose a problem.

[Jose]

The instinct is to "listen to" the pattern of external cues: magnetic fields, landmarks, position of the stars, and whatever the other birds are doing. So an alteration of the earth's magnetic field would not pose a problem.

One of my good friends studies magnetic "homing" in animals, and has found that while some birds have magnetic bits in them, in many other species there's a photoreceptor that is sensitive to light only when aligned in one orientiation with respect to a magnetic field. That is, they actually see the magnetic directions around them. A part of what they follow is the declination of the field, so they can judge north from south not just from being parallel or orthogonal to the field, but also from the "dip" of the field with respect to the earth. Now, how much this would matter if the field reversed, I can't say. If we're lucky (or if they are), you're right that they use a lot of landmarks, and will just be confused for a while. It seems prettly likely that some kind of accomodation is built in, since there have been magnetic reversals in the past--which should have dealt severely with the hard-wired, no-landmarks, no-learning traits.

[otseng]

It may be as simple as any plate bumping into another plate causing an effect on the trajectory of both plates.

However, all plates at all times are adjacent to each other. In addition, what we see are entire continents moving at different vectors than the oceanic ridges. Also, if bumping occurs at plate boundaries, I would expect to see bumping effects near the plate collisions, not entire continents.

Why now? Probably, it has been much like this as long as mantle convection and plate movements have been going on. It's a little tricky to determine the exact trajectories of the continents in the distant past, because the most recent records (seafloor magnetic anomalies) aren't all that old.

But even if we were to restrict it to 200 million years, why do we not see evidence of this occurring since then?

I'll also refer to a prior post, concerning the Emperor's Seamount/Hawaiian Island chain, which records a very clear change in direction in the past. That is, changes in direction aren't just "now"--and are recognizable if we have the right "markers."

I would disagree with the conclusion. If we look at the underwater formations around the "bend", we see no other similar bending. If bending did occur, we should see the exact same bending in the mountains around that area.

The pot of water analogy is adequate for conveying the image, but not the speed. I usually like to think of a pot of oatmeal with a scum on it, in which convection will be much slower.

I think speed is immaterial for my argument. The main point is chaotic vs non-chaotic. Even if a pot of oatmeal was boiled, the convection cycles would be random.

Since we haven't been able to find a global map, I think you'll have to work from what we've already brought to the table.

Since John S had mentioned that all he had to do was scan it, I was hoping to be able to see this diagram. But, until then, perhaps I will have to start discussing this with the limited data that we have.

It's not really fair to dismiss them as mere supercomputer stuff, though we all admit the GIGO rule, and there could be incorrect information as part of the input.

To clarify, I do not dismiss it because it's a supercomputer model. Rather, it doesn't explain the questions I asked.

To reiterate the questions:
What is the mechanism? How does it happen? Are there measurements of the magnetic field that indicate that the earth's magnetic field is reversing in polarity?

In the meantime, the measurements that demonstrate the past reversals are the magnetic anomalies themselves.

To me, this is circular logic. Magnetic anomalies happened because of polarity reversals. Polarity reversals happened because we see magnetic anomalies.

The other model proposes that god created everything exactly as it is, with all of the things in place to make it look like the other model is correct.

Not so. The Flood Model does not say that god created everything to look as it is today. Rather, it offers a rational explanation of the data that we see. God did not have to make anything look like what we see now. No laws of physics were violated, no laws of physics needed to be changed.

As for plate tectonics looking like it is correct, I'm even more skeptical about it now than when this thread first got started. Evidence for it has been sparse and even contradictory. Explanations for mechanisms to explain processes have lacked substantive value. A surface approach to plate tectonics makes it seem plausible. But on a deeper study of it, it fails to hold up under cross analysis.

That is to say that the direction the birds travel is not an instinct, but is learned behavior.

I'm not convinced that animal migration is not instinctive, but I'll leave this for another thread.

[Jose]

It may be as simple as any plate bumping into another plate causing an effect on the trajectory of both plates.

However, all plates at all times are adjacent to each other. In addition, what we see are entire continents moving at different vectors than the oceanic ridges. Also, if bumping occurs at plate boundaries, I would expect to see bumping effects near the plate collisions, not entire continents.

Not to sound silly, but I've just experienced a relevant phenomenon. I bumped the desk at the edge, and it shook my glass of water in the middle, and spilled some. Plate collisions at the boundaries affect the entire plate, just as my bumping the desk affected its entire surface.

Still, a central question remains: the world has given us some data. We must ask what the history might be that has given us these data. We see footprints of magnetic reversals in a region that we know is being built (and likely was built) by magma coming through the cracks at the ocean ridges. What history connects these observations?

Why now? Probably, it has been much like this as long as mantle convection and plate movements have been going on. It's a little tricky to determine the exact trajectories of the continents in the distant past, because the most recent records (seafloor magnetic anomalies) aren't all that old.

But even if we were to restrict it to 200 million years, why do we not see evidence of this occurring since then?

I'm not sure what you mean. We do see evidence of it happening. That is, we see evidence of plate movements and seafloor spreading, and we see evidence of changed trajectories. We have not experienced a change in polarity of the earth's field, but that doesn't happen all that often, and we can't call it up on demand for purposes of study. Phooey.

I'll also refer to a prior post, concerning the Emperor's Seamount/Hawaiian Island chain, which records a very clear change in direction in the past. That is, changes in direction aren't just "now"--and are recognizable if we have the right "markers."

I would disagree with the conclusion. If we look at the underwater formations around the "bend", we see no other similar bending. If bending did occur, we should see the exact same bending in the mountains around that area.

You would be correct in that conclusion, if the Emperor Seamount/Hawaiian Island chain and the other undersea mountains were formed in the same manner. The evidence indicates that they were not. The Island chain is thought to result from the crust passing over a hotspot--a place where, for reasons we don't yet understand, magma seems to come forth with some regularity. As the crust moves over it, we get one volcano after another, as old volcanoes move too far off the hotspot, and new cracks in the crust form in the region that moves over the hotspot. This explains why it is only The Big Island that is currently volcanically active, and why the islands tend to decrease in size as we follow them from southeast to northwest.

By contrast, the other undersea mountains are thought to be of different origin. I can't tell you, off the top of my head, what that origin is. Some of the South Pacific Islands (I think) are thought to be from subduction of plates to their southwest. I suppose that some could be "rumples" in the crust from plate collisions, or some other type of thing. Maybe John can tell us.

Hence, the Emperor Seamount/Hawaiian Island chain provides a record of the Pacific Plate passing over the hotspot, while the other mountains provide records of different events. Presumably the change in direction should also be reflected in a change in the direction of the parallel stripes of magnetic reversals. We can consider this a prediction of the hypothesis that the Pacific Plate changed direction--and when John scans the map, we can look to see if this prediction is met.

We could imagine, perhaps, a map of the plates just before the Pacific Plate changed direction. The Atlantic was considerably narrower, and the Pacific would have been considerably wider. There would be more spreading on the south side of the Pacific Plate than now, especially if we had the smaller plates crashing into N. America to build California. At some point, however, N. America moved over enough to impact the Pacific Plate directly--subducting it to build the Sierra Nevada. This would not only shrink the southern spreading center, but push westward on the Pacifi c Plate itself. Less force purshing north, more force pushing west, and we get a change in direction at about the time that the Midway Island was oer the hotspot. I think this might work, and it might also fit the data.

The pot of water analogy is adequate for conveying the image, but not the speed. I usually like to think of a pot of oatmeal with a scum on it, in which convection will be much slower.

I think speed is immaterial for my argument. The main point is chaotic vs non-chaotic. Even if a pot of oatmeal was boiled, the convection cycles would be random.

I think speed is material , if for no other reason than that it makes it danged hard to measure it and answer the question! Your expectation matches mine, that the oatmeal pot would be random--and I suspect that the global oatmeal pot is also random, but on a very much slower timescale. I also suspect that there is much we don't know--because whatever it is that's random doesn't seem to affect that weirdo hotspot under Hawaii. So, there must be randomness to it, but also enough "lumps in the oatmeal" to keep things from changing very fast.

Since we haven't been able to find a global map, I think you'll have to work from what we've already brought to the table.

Since John S had mentioned that all he had to do was scan it, I was hoping to be able to see this diagram. But, until then, perhaps I will have to start discussing this with the limited data that we have.

I'd forgotten he'd said that. I'm looking forward to it. In the meantime, we can still look at the limited dataset, and ask about possible explanations for the observations.

It's not really fair to dismiss them as mere supercomputer stuff, blah blah blah.

To clarify, I do not dismiss it because it's a supercomputer model. Rather, it doesn't explain the questions I asked.

To reiterate the questions:
What is the mechanism? How does it happen? Are there measurements of the magnetic field that indicate that the earth's magnetic field is reversing in polarity?

(I dunno...I often dismiss computer models because there are usually assumptions that are needed to make the algorithms possible). But it's also not quite right (IMHO) to say that the overall model is unacceptable because there is a complexity for which we have insufficient data to provide a detailed mechanism. (This is why so many of us object so strongly to ID--it says that if there is anything about something that we can't describe in detail right now, then we must conclude that god did it and it is beyond our ability to figure out.) Rather, we do the "scientific thing" and ask "how can I prove that this model is wrong--and at the same time come up with a better model that will make me famous?" Or, we do what the computer guys did, and try to build a computational model, based on things we know about, and see if the model can reconstruct the data. I agree with you that it seems wacky that the magnetic field would fizzle out and then pop back up in reverse orientation...but how else do we explain the magnetic orientations of crystals in the rocks? Again, if it would happen right now, so we could watch it, we'd be able to satisfy all doubters...but alas, we don't know how to make that happen (and I suspect that we don't want to, either).

In the meantime, the measurements that demonstrate the past reversals are the magnetic anomalies themselves.

To me, this is circular logic. Magnetic anomalies happened because of polarity reversals. Polarity reversals happened because we see magnetic anomalies.

A forest is defined as a bunch of trees, and trees are defined as the things that make up a forest. An address is where you store the data, and you know that because data is stored in addresses. There's a lot of this seemingly-circular logic, but straightens out when we see it more fully. The magnetic anomalies are Facts. They seem to be everywhere, so it requires some global phenomenon to create them. This is inference. I imagine that additional data--such as microscale examination of the orientation of magnetic crystals relative to the north/south orientation of the original rock formation--must also be added to the fact list. We probably also have to add to the fact list similar measurements from recent lava beds, to demonstrate alignment with the earth's field. If we see that the current mechanism aligns crystals with the earth's field, and that older rock has crystals aligned in the opposite direction (but there is no evidence of the rock formation spinning 180 degrees), it seems like a pretty good hypothesis that the older crystals aligned by the same mechanism as current crystals do, but the magnetic field must have been reversed.

There are lots of things that haven't been watched, like transcription and translation, or an SN2 reaction, or water moving in the Ogalalla Aquifer--but we have various kinds of information that allow us to infer with reasonable certainty that these things happen. Once we have concluded that the inferences are very likely true, then we might as well talk about them as if they are. We're not saying magnetic anomalies prove the magnetic field reversed, and field reversals prove that magnetic anomalies exist; we're saying the magnetic anomalies exist, and other data exist, and the current best explanation is field reversal--for which we don't have an absolute, proven mechanism, but we have some good ideas.

That's the best we can do with most of science. If you want Absolute Truth, science can't give it to you. The best we can do is offer the current-best explanations, and tell you to be ready when and if new information comes along.

The other model proposes that god created everything exactly as it is, with all of the things in place to make it look like the other model is correct.

Not so. The Flood Model does not say that god created everything to look as it is today. Rather, it offers a rational explanation of the data that we see. God did not have to make anything look like what we see now. No laws of physics were violated, no laws of physics needed to be changed.

I didn't say that the traditional Flood Model says that god did things this way. Rather, the "Appearance of Age Model" says this. The AoA model is the one put forward by some flavors of YECs. A forerunner of it was that the devil put things like fossils in the earth to test our faith.

The thing is, if we use Walt Brown's model, and envision the plates whizzing to their current locations as a result of the "waters of the deeps" issuing from the cracks that currently form the mid-ocean ridges, we still have no explanation for the magnetic reversals, or the microfossils in the thin sediment layers on the seafloor that correlate with the ages inferred from the reversals and from direct measurement. Somehow, those magnetic anomalies got there.

And, of course, the Flood Model, as we've considered it, has no explanation for the current plate movements. It was the result of the water shooting through the cracks that caused the movement. There's no further water coming through. But, there is magma, and there are these curious age differences and magnetic symmetries.

As for plate tectonics looking like it is correct, I'm even more skeptical about it now than when this thread first got started. Evidence for it has been sparse and even contradictory. Explanations for mechanisms to explain processes have lacked substantive value. A surface approach to plate tectonics makes it seem plausible. But on a deeper study of it, it fails to hold up under cross analysis.

I suspect that this is the problem that afflicts us all--as soon as we look into anything deeply, we see that it is more complicated than we first thought. We try to resolve the new questions that we have, and the explanations rapidly become wacky. To get beyond this, we have to learn a whole lot more so that we can interpret the data personally, and not have to rely on anyone else's suggestions. I apologize for helping bring you to this point--it's always a sort of a watershed, from which we either turn back and keep our prior understanding, or past which we go into the muck and mire of the raw data.

That is to say that the direction the birds travel is not an instinct, but is learned behavior.

I'm not convinced that animal migration is not instinctive, but I'll leave this for another thread.

I think we have to conclude that both are part of it. To go home is instinctive. To use certain types of cues is instinctive. Which cues to use often depends on what cues there are. Being able to see the earth's magnetic field is a big plus in establishing a compass. Being able to recognize local landmarks would also be a big plus. To to both would require instinctive behaviors as well as learning.

[otseng]

But even if we were to restrict it to 200 million years, why do we not see evidence of this occurring since then?

I'm not sure what you mean. We do see evidence of it happening. That is, we see evidence of plate movements and seafloor spreading, and we see evidence of changed trajectories. We have not experienced a change in polarity of the earth's field, but that doesn't happen all that often, and we can't call it up on demand for purposes of study. Phooey.

Ah, what I was referring to was the change in vector of the continents relative to the vector of the ridge growths. Let me bring this back to an argument that I made before. We see that currently, ridge growth and continental movement are not related. If they are the same plate, how can they move differently? Can we say that they have always been different? If so, by what basis can we say plate movement is to be measured by? I guess what I'm waiting for is a coherent model to explain what has been presented so far in regards to the continental movement (GPS measurements), ridge growth, ridge lines, and the shape of the continents.

The Island chain is thought to result from the crust passing over a hotspot--a place where, for reasons we don't yet understand, magma seems to come forth with some regularity.

I have several problems with the hotspot theory. One is, do we see much evidence of other hotspots creating volcanoes? And as you mentioned, how did all the surrounding mountains form that were not created by a hotspot?

Presumably the change in direction should also be reflected in a change in the direction of the parallel stripes of magnetic reversals. We can consider this a prediction of the hypothesis that the Pacific Plate changed direction--and when John scans the map, we can look to see if this prediction is met.

I would agree with this prediction. The magnetic stripes should also have a similar bending.

I suspect that the global oatmeal pot is also random, but on a very much slower timescale.

And yet we have a discrepency. Plate tectonics says that mantle convection is not random. The mantle convection would have to have been fixed for periods measured in the millions of years.

Rather, we do the "scientific thing" and ask "how can I prove that this model is wrong--and at the same time come up with a better model that will make me famous?"

The only output of the model that I've seen, and which also makes me highly dubious of the simulation, was the image of the scrambled magnetic field. To me, it does not seem physically possible to have such a field exist.

The magnetic anomalies are Facts.

I would agree with that and do not dispute it. But, what I do dispute is that it necessarily leads to the conclusion that the magnetic field of the earth has reversed in polarity every thousands/millions of years. What other evidence besides magnetic anomalies would point to the fact that the earth has experienced many magnetic polarity reversals?

That's the best we can do with most of science. If you want Absolute Truth, science can't give it to you. The best we can do is offer the current-best explanations, and tell you to be ready when and if new information comes along.

Certainly.

The other model proposes that god created everything exactly as it is, with all of the things in place to make it look like the other model is correct.

Not so. The Flood Model does not say that god created everything to look as it is today. Rather, it offers a rational explanation of the data that we see. God did not have to make anything look like what we see now. No laws of physics were violated, no laws of physics needed to be changed.

I didn't say that the traditional Flood Model says that god did things this way. Rather, the "Appearance of Age Model" says this. The AoA model is the one put forward by some flavors of YECs. A forerunner of it was that the devil put things like fossils in the earth to test our faith.

Ah, I assumed you were talking about the Flood Model since that is the competing model to plate tectonics.

The AoA is probably worthy of discussion in its own thread (and hopefully won't be created too soon to derail me from this thread!).

And, of course, the Flood Model, as we've considered it, has no explanation for the current plate movements.

Actually, I've been thinking about this and developed a hypothesis to match the data that we see.

I apologize for helping bring you to this point--it's always a sort of a watershed, from which we either turn back and keep our prior understanding, or past which we go into the muck and mire of the raw data.

I'm actually learning a lot here. And I'm also willing to plow through this thread until more evidence and explanations are presented.

[ST88]

The Island chain is thought to result from the crust passing over a hotspot--a place where, for reasons we don't yet understand, magma seems to come forth with some regularity.

I have several problems with the hotspot theory. One is, do we see much evidence of other hotspots creating volcanoes? And as you mentioned, how did all the surrounding mountains form that were not created by a hotspot?

Yes, in fact there are several other chains with accompanying hotspots:

From the site:

These islands are all shield volcanoes built up of basaltic lavas. The basalt that makes up these islands contain significantly more potassium and sodium than the basalts which make up the ocean crust. This suggests that while the mantle forms the source for both these rocks... there must be a different mechanism involved in their formation.

Other islands and seamounts, such as those around the Western Pacific, (Solomon Islands, Vanuatu, Fiji, Samoa, Guam, Micronesia, etc.) tend to congregate around the boundaries of the Australian/Pacific plate convergence and the Philippine/Pacific plate convergence.