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Continents Adrift (Geophysics)
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Mick Harper
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There are many strands of evidence that support 'plate tectonic theory'. These are drawn from a wide variety of disciplines.

Well now, in Applied Epistemological terms, you are both right and wrong. Academic principles require that one discipline must take on trust the paradigm assumptions of other disciplines. (Such rigid uniformity is possibly why they are called 'disciplines' in the first place.) But this leads ineluctably to one discipline being required to use a neighbouring discipline's paradigm in its own explanations and this can lead to a merrily circular dance.

For instance, as soon as biologists found there were marsupial mammals specifically but uniquely in Madagascar, South America and Australia they were perforce obliged to construct elaborate land bridges between these places to account for it. Then along came Continental Drift, and they (with considerable relief) said, "Aha, the marsupials evolved on one continent which then split up into three continents and then drifted to their present locations."

"Aha," said the Earth Scientists, "this means we have living proof of our theory" and they constructed Pangea. Once you have constructed Pangea AND you have the present location of Madagascar, South America and Australia, you can compose a nice computer graphic showing the original continent and how it split and drifted. And shortly thereafter we have living history in your sitting room. "Mummy, mummy, come and look, the continents are drifting...it's on telly!" "Yes, darling, and it is evidence that is drawn from a wide variety of disciplines."

Nothing that you have said counters directly observed phenomena.

Nothing anybody says can contradict a carefully constructed academic paradigm -- they always contain some circularity that ensures their indefinite survival. I think probably only true paradigms can be overthrown by directly observed phenomena (as Newtonian physics was by Mercury's perturbations).

There is direct evidence of 'oceanic' rock being created at the Mid Atlantic Ridge.

Yes, we all watched Surtsey bursting forth. What there is not direct evidence of is that Surtsey was pushing America and Europe apart.

The Earth's surface is not expanding so crystal rock is being destroyed (evidence of which comes from the salty gases released by Andean volcanoes). There are many other examples.

Well, the one you have chosen isn't terribly persuasive.

I would agree that the boundaries between plates are poorly understood in many places.

Applied Epistemologists should always look out for the phrase "poorly understood". It is the term academics currently use for "Fookin 'ell, we've got a reet royal anomaly on our 'ands this time, and no mistake. Best make a virtue out of modesty."

I am not sure if you mentioned it but the Rift Valley in Africa is thought to be the result of the African continent splitting and will one day form a new ocean (the Red Sea is part of this) thus making Africa an O continent?

I am sure I have mentioned it but the African Rift Valley is the old bed of the Nile (the Red Sea is part of it). Unless of course you wish to argue that the two greatest geographical features of this narrow strip of the earth mirror one another for thousands of miles out of sheer coincidence. You are perfectly correct of course to say that in many millions of years' time, on your reading of the Rift Valley, Africa will indeed be an O-continent. If Plate Tectonics is correct, in many millions of years' time all the present continents will be O-continents. The question is, why aren't any of them now.

I would also agree that some plates do not seem to fit the pattern.

I am intrigued. Since plates are entirely imaginary artefacts dreamed up by Earth Scientists I would have have thought they would at least have made them to a pattern. But their incompetence in this area is legendary. If you can overcome your natural defensiveness, I would very much like to hear more from you on this.

[The actual explanation for the lack-of-pattern is thusaway:
1. Plate Tectonics was grafted onto the back of Continental Drift. It soon became evident that a 'plate' that fitted one theory didn't always fit the other, so two types of plates have gradually come into existence -- ones that fit with the continents and ones that don't.
2. Since it is assumed that all major tectonic events have a (Plate) tectonic cause, a plate boundary had to be inked in every time a major earthquake, tsunami, volcanic eruption occurs. These new plate boundaries didn't necessarily coincide with the two existing types of plates described above, so "platelets" were born.
3. We now have continental plates, non-continental plates and platelets -- and every eventuality is catered for.]

However I don't think you are really challenging the crux of the theory.

No? Then you must give your explanation as to why Plate Tectonics has given us all-X continents when it theoretically "predicts" a preponderance of O-continents. You may, if you wish, say, "Just an unlucky accident of timing, guv. You wait, in a few million years, you'll see I'm right."
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Martin



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I think the main problem is that you have extrapolated outwards from one example. Is India typical or representative?

If Plate Tectonics is correct, in many millions of years time all the present continents will be O-continents. The question is, why aren't any of them now.

The fault in your logic lies in the assumption you make about continents splitting.

AfricIndia starts to split ie Africa and India are now two X-continents

I don't understand what predisposes continents to split. I would say this behaviour is atypical of most present continents and so we could argue most continents in the past.

All you have shown is that most of the Earth's continents do not behave like the Indo-Asian example which is fairly obvious.
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Mick Harper
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I think the main problem is that you have extrapolated outwards from one example. Is India typical or representative?

Scusi, Martini, but 'tis not I that chose it. Plate Tectonic theorists always use this example (and occasionally Italy breaking away from Africa, bashing into Europe and making the Alps) because they have no others. Their theory rests on constant splitting and constant bashing but nowhere else in the world do we have this "clear" evidence of it having happened. So, since you're taking the side of the PT-ists in this, you'll have to tell us whether it is typical or representative.

If Plate Tectonics is correct, in many millions of years time all the present continents will be O-continents. The question is, why aren't any of them now.

The fault in your logic lies in the assumption you make about continents splitting
.

I am unutterably baffled. PT Theory requires continents to periodically split and periodically bash. But mostly doing neither. My only 'assumption' is that this is a true rendition of PT Theory. If I am wrong in this, you must say. It is true that I have put forward continental candidates for splitting-and-bashing (of which India, remember, is not one) but if you disagree with any of my verdicts, again you must say which ones. Otherwise we are both left with all 'O' continents when PT Theory says there should be hardly any.

AfricIndia starts to split ie Africa and India are now two X-continents

I don't understand what predisposes continents to split. I would say this behaviour is atypical of most present continents and so we could argue most continents in the past.

If you say so but surely that strengthens my case? If continents hardly ever split then it would be even rarer for any world to have any splitting- or bashing-continents at any one time than I had initially supposed (granted PT of course). We have all six of ours doing one or t'other.

All you have shown is that most of the Earth's continents do not behave like the Indo-Asian example which is fairly obvious.

I'm not sure strict PTist theoreticians would be very happy with your position since you appear to believe that Plate Tectonics has difficulty producing discrete continents at all!
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Martin



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That gives us five and a half continents out of six that are X and one that is X/O. Now we've got the figures for earth
Otherwise we are both left with all 'O' continents when PT Theory says there should be hardly any
.

I am a little confused. So are most of Earth's continents X or O?

The Himalayan formation is termed a collision boundary. This type of boundary is found in fewer global locations than destructive or constructive boundaries.

The time scale you used to calculate the different ratios...

1) Continents are in an O condition for 230 million years (that's 100 mill plus 30 mill plus 100 mill).
2) Continents are in the X position for ten million years (that's five million plus five million).
3) So the ratio between O and X is 23 to 1.
Actually this is not very precise because it ignores on the one hand that during 2) there is also a continent in the O position but on the other hand it also ignores the fact that during 1) both Africa and Asia might be X continents elsewhere at other points of their very extensive littorals. So let's be on the safe side and assume very conservatively that
4) The ration between a continent in the O position and the X position is 10 to 1
.

...is based on one this one example. So consequently...

Chart:
All continents are O none are X >>>>>> 61 worlds
Four continents are O two are X >>>>>> 38 worlds
Two continents are O four are X >>>>>> 0 worlds
No continents are O all are X >>>>>> 1 world

...this doesn't mean much. Distances and speeds will vary around the globe.

Plate Tectonic theorists always use this example (and occasionally Italy breaking away from Africa, bashing into Europe and making the Alps) because they have no others.

Take care here there are other examples. Off the top of my head South America used to be made up of two continents that were joined and the great Glen Fault in Scotland was formed when the two landmasses collided.

I'm not sure strict PTist theoreticians would be very happy with your position since you appear to believe that Plate Tectonics has difficulty producing discrete continents at all!

Yes I imagine they wouldn't, by my understanding of Plate Tectonics there is a strong inclination for continents to bunch up. What I find surprising is that there are so many discrete continents.
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Mick Harper
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That gives us five and a half continents out of six that are X and one that is X/O. Now we've got the figures for earth Otherwise we are both left with all 'O' continents when PT Theory says there should be hardly any.

I am a little confused. So are most of Earth's continents X or O?

I get a little confused myself. I think I probably meant X continents here. (I'll go back and check and amend if necessary...though it's significant that nobody else noticed...mmm..). At any rate I'm putting forward the thesis that all Earth's continents are X when Plate Tectonics says they should be mostly O. Originally they were called Discrete and Non-Discrete continents but that didn't work either. If you, or anybody else, can come up with a really memorable pair of labels I'd be eternally grateful, and you'd get your name in a footnote for ever.

The Himalayan formation is termed a collision boundary. This type of boundary is found in fewer global locations than destructive or constructive boundaries.

Well, I'm often being told things like this. Because plates bashing into each other or separating or shearing or subducting or interacting in any kind of way is all entirely imaginary -- or at any rate entirely unevidenceable in any scientific way -- then orthodoxy just changes the rules whenever it is convenient. In the old days, when India and Italy were all the rage, collisions were very popular (and of course, strictly speaking, in a dynamic system, about half of all plate boundaries must by definition be colliding) but, as you say, the more emollient terms 'destructive or constructive' are nowadays preferred. That's the thing about Plate Tectonics: the forms of the earth are so variable and the plate boundaries are so arbitrary that anything goes. Nothing can be proved, nothing can be disproved.

The time scale you used to calculate the different ratios...
1) Continents are in an O condition for 230 million years (that's 100 mill plus 30 mill plus 100 mill).
2) Continents are in the X position for ten million years (that's five million plus five million).
3) So the ratio between O and X is 23 to 1.
Actually this is not very precise because it ignores on the one hand that during 2) there is also a continent in the O position but on the other hand it also ignores the fact that during 1) both Africa and Asia might be X continents elsewhere at other points of their very extensive littorals. So let's be on the safe side and assume very conservatively that
4) The ration between a continent in the O position and the X position is 10 to 1.
...is based on one this one example

Well, only illustratively. Do you know of any example that is particulary different? Have another look at your videos of the Great Pangea break-up or Gondwanaland's epic voyages. Or Europe and North America or any example of continental drift that you personally have signed up to. Don't they demonstrate the same ball-park figures that I have used?

So consequently...

Chart:
All continents are O none are X >>>>>> 61 worlds
Four continents are O two are X >>>>>> 38 worlds
Two continents are O four are X >>>>>> 0 worlds
No continents are O all are X >>>>>> 1 world


...this doesn't mean much. Distances and speeds will vary around the globe.

Listen, popsicle, this is your theory not mine. You've got tens of thousands of Earth Scientists all relying on a theory that says continents go round either splitting or bashing into each other. Presumably they've worked out some ball-park figures for these tales of derring-do. If you think my (honestly, if anything rather conservative) assumptions are way off, then come up with some of your own. Bet yer can't. Or, as we say in Applied Epistemology, bet you won't even try.

Plate Tectonic theorists always use this example (and occasionally Italy breaking away from Africa, bashing into Europe and making the Alps) because they have no others.

Take care here there are other examples. Off the top of my head South America used to be made up of two continents that were joined


Oh really? Orthodoxy doesn't usually like to put South America into the mix because the Andes are remarkably similar to the Alps and the Himalayas and yet for some reason they can't find a convenient continent to bash into South America. No wait, don't tell me...let me guess...it was the Nazca Plate that jumped up, bashed into South America, caused the Andes and then...er...jumped back down again.

and the great Glen Fault in Scotland was formed when the two landmasses collided.

Ah, I think I'm beginning to get the hang of this .When two landmasses collide they either cause a mountain range or the opposite, a glen. Them plates...true artists.

I'm not sure strict PTist theoreticians would be very happy with your position since you appear to believe that Plate Tectonics has difficulty producing discrete continents at all!

Yes I imagine they wouldn't, by my understanding of Plate Tectonics there is a strong inclination for continents to bunch up. What I find surprising is that there are so many discrete continents.

Well, you haven't told us why they bunch up. Though of course you should be telling the Plate Tectonicists since this would be a radical reformation of the theory. If you do give us your "bunching-up theory" I can promise, by the rules of the AEL, that it will be given a hospitable welcome. Of sorts.
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Martin



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I agree something is wrong with PTT.

This is how I understand PTT and what I would expect to happen...

There are two kinds of crust; continental and oceanic. Continental is light, lighter than mantle rock and so cannot be subducted. As a result it is old. Oceanic crust is dense, denser than mantle rock and so can be subducted. Consequently it is much younger.

Plates can; push together, pull apart or rub side to side. Now here there is also knock on effect; if a plate is pulling apart the opposite edge of that plate must be pushing against another plate and either colliding or subducting.

We have some scenarios:

1. Plates move apart. All continental crust will be drawn away from the boundary.
2. Plates move together. All continental crust will be drawn to the boundary. There it will not be able to subduct and so the two land masses will collide.
3. Plates rub together. There is no movement of continental crust.

All point to a 'build up' of continental crust at all destructive boundaries... and so continents will group together.

Anyway something for you to kick about.
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Mick Harper
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I agree something is wrong with PTT.

Why do you think that? It cannot surely be because of the bunching-up. You must have had pre-esisting reservations. I concede it will be giving ammunition to the enemy but can you say the original cause of your misgivings.

This is how I understand PTT and what I would expect to happen... There are two kinds of crust; continental and oceanic. Continental is light, lighter than mantle rock and so cannot be subducted. As a result it is old. Oceanic crust is dense, denser than mantle rock and so can be subducted.

The AE position (if I may arrogate it) is that there is no such thing as mantle or crust -- they are essentially academic artefacts. Or at any rate, they are a current model for which the evidence is too thin to base any universal paradigm on. It is a more specialised position (of mine and some others, all of whom are Applied Epistemologists of one sort or another) that there is no such thing as continental or oceanic crust. Though there are two sorts of earth-stuff, one of which tends more to be under the ocean.

Consequently it is much younger
.
You have to be most careful when speaking about "younger rock" -- this is a favourite AE concern and can be applied to all manner of things from languages to DNA: all rocks are of exactly the same age; when you speak of "newer" you mean rocks that have acquired their present appearance more recently than others.

Plates can; push together, pull apart or rub side to side. Now here there is also knock on effect; if a plate is pulling apart the opposite edge of that plate must be pushing against another plate and either colliding or subducting.

Actually, this is the major unstated weakness of the entire theory. In order for the system to work, plates have to be rigid enough to be acting discretely one-on-one, but this means they must also be 'jostling' all the other plates they happen to be adjacent to. With knock-on effects world-wide. I have been watching intently but so far there is not a single example of a PT-ist, when jumping up to explain how the latest tsunami (or whatever) is caused by Plate A splitting/colliding/shearing Plate B saying, "Of course this means we can expect some action at the boundary with Plate C, D, E...n."

We have some scenarios:
1. Plates move apart. All continental crust will be drawn away from the boundary.
2. Plates move together. All continental crust will be drawn to the boundary. There it will not be able to subduct and so the two land masses will collide.
3. Plates rub together. There is no movement of continental crust.
All point to a 'build up' of continental crust at all destructive boundaries... and so continents will group together
.

Sorry, but this smacks of "with one bound they were free". I can't see any reason why the three actions (which I agree are the only possibilities for plate movement) should lead to bunching up.

Anyway something for you to kick about.

I'd like to but you haven't provided the actual ball.
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Martin



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It is a more specialised position (of mine and some others, all of whom are Applied Epistemologists of one sort or another) that there is no such thing as continental or oceanic crust. Though there are two sorts of earth-stuff, one of which tends more to be under the ocean.

Ok, let's call it the earth-stuff which tends to make up the continents. This stuff cannot be subducted because it is denser than the underlying stuff. Is this true?

when you speak of "newer" you mean rocks that have acquired their present appearance more recently than others.

Yes that sounds like a good definition to me. I don't see why I have to be careful using a term like this, it is surely self evident.

So the earth-stuff which tends to make up the continents is much older than the earth-stuff that tends to be found under the oceans. (Is it not easier to call them continental and oceanic crust as a form of shorthand?) This is unsurprising as the continental earth-stuff cannot be subducted, right?

So what happens to this continental earth stuff when the 'plates' move? It moves with them.

We agree on the three possible scenarios of plate movement:

We have some scenarios:
1. Plates move apart. All continental crust will be drawn away from the boundary.
2. Plates move together. All continental crust will be drawn to the boundary. There it will not be able to subduct and so the two land masses will collide.
3. Plates rub together. There is no movement of continental crust.

Ask where is the continental earth-stuff going in scenario1- away from the boundary. What about scenario 2- toward that boundary
3. There is no movement.

So in scenarios 1 and 2 we have a situation where continental earth-stuff is building up at a 'destructive' boundary.

I'd like to but you haven't provided the actual ball.

Who said anything about a ball.
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Mick Harper
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Ok, let's call it the earth-stuff which tends to make up the continents. This stuff cannot be subducted because it is denser than the underlying stuff. Is this true?

...umm...I do not accept the notion of subduction. I do not accept that denser cannot subduct underneath less dense (why ever not?). I do not accept (necessarily...you'd have to convince me) that continental earth-stuff is more dense than non-continental stuff (every time I look I see teeny differences based on careful selection). Nor, and I am really sorry because you might choose to give up with me here, do I accept that there is "continental stuff". There is only
a) stuff that has been exposed to geographical forces (the upper levels of the present continental landmasses, the continental shelves and a lot of the ocean) and
b) stuff that hasn't, which reaches the "surface" at the really deeper parts of the abyssal plain plus the rest of the earth.

when you speak of "newer" you mean rocks that have acquired their present appearance more recently than others.

Yes that sounds like a good definition to me. I don't see why I have to be careful using a term like this, it is surely self evident
.

Yes, it seems so, doesn't it? But you'd be surprised how often people lose sight of this. You, you'll have to admit, had never actually thought of it this way before.

So the earth-stuff which tends to make up the continents is much older than the earth-stuff that tends to be found under the oceans.

See what I mean? I'll agree that terrestrial rock forms near the surface of continental landmasses have taken their present form more recently than the undisturbed geology of the abyssal plain.

(Is it not easier to call them continental and oceanic crust as a form of shorthand?)

I don't really accept the notion of "crust", at least not in the way you mean it..

This is unsurprising as the continental earth-stuff cannot be subducted, right?

I have no idea.

So what happens to this continental earth stuff when the 'plates' move? It moves with them.

I don't accept the existence of plates but I am prepared to accept that everything would get moved by such gynormous forces.

We agree on the three possible scenarios of plate movement:
We have some scenarios:
1. Plates move apart. All continental crust will be drawn away from the boundary.
2. Plates move together. All continental crust will be drawn to the boundary. There it will not be able to subduct and so the two land masses will collide.
3. Plates rub together. There is no movement of continental crust.
Ask where is the continental earth-stuff going in scenario1- away from the boundary. What about scenario 2- toward that boundary
3. There is no movement.
So in scenarios 1 and 2 we have a situation where continental earth-stuff is building up at a 'destructive' boundary
.

I cannot follow this very well but it sounds not implausible. That's the problem with all Plate Tectonic theses -- they always sound not implausible -- they wouldn't be advanced if they didn't. I must ask you though, since all this is presumably perfectly understandable to and therefore perfectly acceptable to, orthodox plate tectonicists, why hasn't it been embraced into their theory? I hope you're not suggesting they're thick, a bit slow on the uptake, and generally fit for nothing more intellectually challenging than bashing rocks with hammers.
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There is an alternative theory. It is based on the observations that:

1. The major Northern contents are broadly flat along the top
2. Most continents have pointy bits at the bottom

It's called Continental Drip.

Just thought I'd mention this in order to confuse matters.
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Mick Harper
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Ishmael came up with something about this (perhaps he'll reprint his original observations here) but it's news, I think, to all of us that it's an actual "theory". Or is it? A quick Google brings up
http://www.dazbert.co.uk/sites/science/index.php?id=issue3
which suggests it's all a giant piss-take. Wouldn't be the first time a joke's turned serious. I remember during my early work how I seemed to be contantly retreading the footsteps of Slartibartfast and his chums in the Hitchhiker's Guide To The Galaxy.
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Ishmael


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Mick Harper wrote:
Wouldn't be the first time a joke's turned serious. I remember during my early work how I seemed to be contantly retreading the footsteps of Slartibartfast and his chums in the Hitchhiker's Guide To The Galaxy.

Quite fascinating that others have noticed the phenomenon. This page does appear to have humorous intent but the phenomenon is real and needs explaining. I do have an explanation that has the added benefit of solving a great many more mysteries when applied to a wider context.
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oddlad


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Well met Gentlemen and Ladies, I hope you do not mind my joining the discussion at this point.

Having read the previous posts I got to thinking about the juices, or otherwise, under our feet. If the plates are moving, why are they doing so, and what drives them to do this?

After a very painstaking and very thorough 30 second search, I came up with the following, taken from answers.com...

It is now considered highly unlikely that convection currents within the mantle drive the movement of tectonic plates (as the mantle is in fact solid). It is now thought that seafloor spreading is caused by the 'drag' from the plate subducting at the other end. The mantle melts because when the plates move apart pressure is reduced, leading to a reduction in the melting point of the mantle close to the surface.

Aha! So the mantle is solid! Hmmmm....

My previously unpolluted mind imagined a kind of 'floating island' situation, where each island butts up to the next, some slipping underneath, some in a state of equilibrium. However, upon reading the above, I am now confused as to the depth that a plate stops being a plate. Where is the movement taking place? Why do we not live on a world plagued by constant earthquakes? Why does subduction not 'drag' the mantle immediately behind the moving 'solid' mantle and so forming a constant state of equilibrium?

Oh and finally, let's assume that subduction is the driving force. It must be one helluva pull. Is there anyway that this could be quantified?

So many questions, so little grey matter....
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Mick Harper
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Welcome, Oddbins, and let me say what sure Applied Epistemological instincts you seem to have. The AEist always begins with a thirty-second search. Why? Because a source like answers.com can be completely relied on to summarise with great fidelity the unvarnished bottom line, the paradigm belief, the basic assumption upon which the entire academic subject is built. If, on the other hand, you settle down with Principles of Geophysics (or worse, begin a degree in the Earth Sciences) you'll get the same idea but your brain will be reeling with a whole lot else.

I actually didn't know our Masters now think everything is solid either but that's not the point. You spotted a significant thing: that our Masters had all this time been insisting that everything 'down there' was plastic and coming up with exactly the same set of conclusions as they do now when they suppose it to be solid. This is how AE starts, with the teeniest suspicion that they will say anything because in fact they know nothing.

Your next step might be a little more fundamental and wonder whether the mantle itself exists.
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Brian Ambrose



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There is no such thing as continental drift.

The simplest explanation for what we see, and the one that most fits all the evidence is that the Earth is expanding. This theory has a long history as you will see from a quick internet search, but here's a site with some material that goes into detail:
http://www.geocities.com/CapeCanaveral/Launchpad/8098/1.htm ) also
http://www.geocities.com/CapeCanaveral/Launchpad/8098/EARTHEXP.htm
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