What is the Proof for Plate Tectonics

[Trog]

Can anyone correct me if the following statement is wrong:

 

I assume there we cannot conduct a conventional experiment to prove plate tetronics. The proof lies in the following:

 

1. The theory fits observed data
2. The theory predicts which prove true when we check them

[Ophiolite]

You are correct.

 

I view geology as an experimental science in which the experiments have been conducted by nature. The tasks of geologists is then twofold: to discern the nature of the experiment - science as stamp collecting, then to determine the meaning of the results - science as theory creation. This has worked admirably in plate tectonics.

[Echion11]

Satellites have/can/will measure the movement of the plates. Which is a couple of centimers per year if I am correct.

 

Besides that, it is also the theory which fits best with the data. It explains why we find rocks normally found in the tropics or deserts in areas surrounding the poles but even on antarctica itself. You could also think about fossils which match on very different continents and magnetite in magmatic rocks which point to very different poles than we have today. Surely you could find a theory for everyone of them, but as far as I am aware of continental drift is the only one that links them all.

 

 

[Ophiolite]

. Surely you could find a theory for everyone of them, but as far as I am aware of continental drift is the only one that links them all.

Please note that plate tectonics is a spceific (in some regards a a very specific) variation of continental drift. Several of your 'proofs' support continental drift, but are neutral towards plate tectonics.

[Echion11]

Please note that plate tectonics is a spceific (in some regards a a very specific) variation of continental drift. Several of your 'proofs' support continental drift, but are neutral towards plate tectonics.

 

I don't see how you could get continental drift without plate tectonics. Please enlighten. I don't really see the problem with what I said. Surely you could add seismic activity and convection to get a clompleter story.

[Ophiolite]

I don't see how you could get continental drift without plate tectonics. Please enlighten. I don't really see the problem with what I said. Surely you could add seismic activity and convection to get a clompleter story.

Earlier versions of continental drift envisaged the light continents (sial) flaoting on the denser oeceanic material (sima) thought to envelope the entire Earth. The continents moved over the ocean basins in this hypothesis. Plate tectonics is quite different in that it postulates elements of either continental, oceanic, or mixed character moving discretely.

The implications for the mechanisms and resulting tectonic, igneous and metamorphic patterns are radically different.

[Echion11]

Earlier versions of continental drift envisaged the light continents (sial) flaoting on the denser oeceanic material (sima) thought to envelope the entire Earth. The continents moved over the ocean basins in this hypothesis. Plate tectonics is quite different in that it postulates elements of either continental, oceanic, or mixed character moving discretely.

The implications for the mechanisms and resulting tectonic, igneous and metamorphic patterns are radically different.

 

 

Oh I'm sorry, I was unaware of the earlier hypothesis.

[creationist]

hello,in responce to the question about plate tectonics, there are some problems with the current view of how plate tectonics work...first,in trying to develop a 3D model of the earth assuming mantle convection as the power source for moving the continents..the circulation patterns in no way match up to the observed positions of the continents..secondly,and most important....subduction as is described in the textbooks is not possible...in other words,you cannot subduct a thin brittle lightweight slab under a dense,compressed mass.

[Moontanman]

hello,in responce to the question about plate tectonics, there are some problems with the current view of how plate tectonics work...first,in trying to develop a 3D model of the earth assuming mantle convection as the power source for moving the continents..the circulation patterns in no way match up to the observed positions of the continents..secondly,and most important....subduction as is described in the textbooks is not possible...in other words,you cannot subduct a thin brittle lightweight slab under a dense,compressed mass.

 

 

Do you have any evidence to back up your assertions?

Edited October 21, 2010 by Moontanman

[Ophiolite]

there are some problems with the current view of how plate tectonics work.

Correct. We don't know the relative importance of slab pull, MOR push, and current drag. We don't know what initiates a MOR or a subduction zone in a particular location. We don't know what terminates a MOR or subduction zone at a particular time. We have not conclusively established what determines the angle of descent of the subducting lithosphere. We are not sure of the role played in production of mantle plumes by the D-layer. I could go on, but this is sufficient to demonstrate the accuracy of your statment.

 

first,in trying to develop a 3D model of the earth assuming mantle convection as the power source for moving the continents..the circulation patterns in no way match up to the observed positions of the continents..

Why would you expect them to? A stable tetrahedral, cubic, or hexagonal pattern is only possible at low values (less than about 30) of ru, the viscosity ratio across a layer. Since mantle values are higher than this such stable patterns are automatically precluded. Unsteady, asymmetric convection is to be expected under the conditions pertaining in the mantle, so that complexities of convection cells should show chaotically variable behaviour in time and space, matching just what we observe. As our FEA models improve, as computer processing speeds increase, we will approach closer to effective models of cell geometry and its relation to plate distribution.

 

..secondly,and most important....subduction as is described in the textbooks is not possible...in other words,you cannot subduct a thin brittle lightweight slab under a dense,compressed mass.

Really? What is your explanation for Benioff zones?

[creationist]

hi, in responce to your question concerning Benioff zones.........if the area we know of as the Pacific basin were suddenly depressed by several miles,the outer edges would crack in an angular fashion all around the perimeter at an angle roughly repesentitive of the current observed Benioff zones. this would leave an unstable ring around the Pacific where,in the Earths efforts to become more spherical,would be the area most likely to shift..resulting in volcanos and earthquakes. how did the Pacific sink several miles suddenly??? sounds like a fairy tales right?? so did the helio-centric veiw when it was first postulated. if the Earth had originally an unbroken granitic crust with 3/4 mile of water trapped 10 miles down slowly building pressure..the gravitational tides would eventually cause this water (in superfluid state) to erupt through the crust..as the rip traversed the globe, it would erode quickly enough rock around the rip to cause the underlying basalt in its hot pressurized plastic form to suddeny spring up several miles..thus the opposite side of the Earth wound sink in responce to this..thus explaining the appearance of Benioff zones. of cource since none alive today were there,we can only try to put the observed with physical laws to postulate what happened...this is what Werner did,and scientists can only do today,having spoken to Earth science professers from several prominent universities,they mostly agree at least that this idea is at least possible..but cannot say so publicly for fear of reprisals this is not my idea of course this took a much greater mind than mine to make that leap,but seems at least,to better fit what is observed .

 

p.s. ....please forgive my spelling..it dosent mean im retarded or wrong automaticly...lol.. >^..^<

 

also..in responce to "why would you expect them to"..two things you have missed in your responce that may change the values...first,recent discoveries have shown the mantle to be very heterogenious,implying no admixture has occured..second,the "crossover depth" has shown that every thing below 400 miles sinks,everything above rises.that only applies to liquid magma..the mantle is a solid,so convection cannot occur at all, least by our currant understanding of how slolids behave under great pressure.

[Ophiolite]

hi, in responce to your question concerning Benioff zones.........if the area we know of as the Pacific basin were suddenly depressed by several miles,the outer edges would crack in an angular fashion all around the perimeter at an angle roughly repesentitive of the current observed Benioff zones.

I am afraid that making one unsubstantiated statement in support of another unsubstantiated statement will not cut it in science.

 

1. You need to demonstrate that this claim has any merit whatsoever. Alleging that "Earth science professors from several prominent universities mostly agree that the idea is at least possible" is not sufficient. Who are these professors? When did they agree as to this plausibility? Are you confusing a polite brush off in the question and answer session at the end of a public seminar with a definitive statement in a peer reviewed journal.

 

2. How do you account for the complexity of Benioff zones in the western Pacific? What explains the quite different complexities alon the western seaboard of the US? How will you explain the Basin and Range province if you remove the plate tectonic explanation? How do you account for the Benioff zones that are present in areas other than Circum-Pacific? How (near to my heart) do you account for the genesis of ophiolites? Etc.

 

3. As an extension of the two above, what feature of observed Earth character does a subsiding Pacific Basin better explain than plate tectonics.

 

. how did the Pacific sink several miles suddenly??? sounds like a fairy tales right?? so did the helio-centric veiw when it was first postulated.

The helio-centric view was based upon impeccable observation and irrefutable logic. That's the difference.

 

if the Earth had originally an unbroken granitic crust with 3/4 mile of water trapped 10 miles down slowly building pressure.

There is no evidence that the Earth ever had such a crust. There is no evidence that a layer of water was ever so trapped. There is absolutely no mechanism that would create a planet with these characterisitics that is even remotely consistent with observations from geology, geophysics, chemistry, physics, or astronomy. There are a plethora of interlocked bodies of evidence establsing how the Earth formed and how it evolved. There is zero (metaphorical) room for a trapped body of water beneath a continuous granitic crust.

 

If you have evidence to support any part of this absurd postulate please present it now.

 

..the gravitational tides would eventually cause this water (in superfluid state) to erupt through the crust..

Let's concede for argument that the reservoir exists: why would the tides eventually cause the water to erupt? What triggers the eruption? Why is the water in a superfluid state? (What do you think is meant by a superfluid state?) If you are unable to provide clear, specific answers, then this is even weaker than a vague speculation.

 

..as the rip traversed the globe, it would erode quickly enough rock around the rip to cause the underlying basalt in its hot pressurized plastic form to suddeny spring up several miles...

Describe what constitutes a basalt in hot pressurised plastic form. At one point I contemplated doing a Ph.D. on a topic relating to the origin of basalts. I have remained in peripheral contact with some of the advances in this field. I have never heard of a hot pressurised plastic form of basalt. Please detail for me its chemical and mineralogical composition. Is this a thoeleite, an olivine basalt, a komatiite?

 

How does such a basalt emerge from a subsurface that does not have the composition of a basalt? How is the complex layered nature of oceanic crust derive from this singular emplacement? How do you account for the clear evidence that the oceanic crust was emplaced by successive vertical additions over millions of years?

 

 

this is not my idea of course this took a much greater mind than mine to make that leap,but seems at least,to better fit what is observed ..

Don't sell yourself short. I have hopes you are considerably smarter than the dickhead who spewed that nonsense.

 

 

also..in responce to "why would you expect them to"..two things you have missed in your responce that may change the values...first,recent discoveries have shown the mantle to be very heterogenious,implying no admixture has occured..

They do not imply this at all. The heterogeneity of the mantle is well recgonised and has informed the determination of Rayleigh numbers and ru values. Surely you understand that increased heterogeneity must necessarily encourage higher values of ru, thus making symmetric, stable cell patterns even more unlikely. So your 'recent discoveries' further undermine your speculation.

 

Secondly, the heterogeneity of the mantle is a consequence of several mechanisms. These include partial melting, crystal fractionation, chemical fractionation, recycling of oceanic crust, absorption of subducting slabs, selective devolatisation, absorption of water saturated terrestrial accretion wedges, etc. The majority of these mechanisms occur as a consequence of the subduction process.

 

second,the "crossover depth" has shown that every thing below 400 miles sinks,everything above rises.that only applies to liquid magma...

Forgive me creationist, but you are waffling. You cannot say, on the one hand that everything above rises, then on the other that this only applies to liquid magma. What were you trying to say here?

 

..the mantle is a solid,so convection cannot occur at all, least by our currant understanding of how slolids behave under great pressure.

A word of advice: if you ever wish to be taken seriously in discussions on this topic it would be best not to display your gross ignorance so openly. There is nothing wrong with being ignorant: we are all ignorant of most things, but try not to wear your ignorance like a badge of honour. Go read some elmentary textbooks on geophysics. The ability of the solid mantle to flow is not only well established, but is wholly consistent with our understanding of physics, the properties of materials, and the composition of the mantle.

 

I do not intend to call you ignorant without providing a means to remove that ignorance. I presume you have ready access to a good university library, since it would be insane to challenge such a well established theory as plate tectonics without such acccess. (And of course you are on speaking terms with Earth science professors from several prominent universities.) These documents may aid you in your education:

 

Arthur Holmes established the possibility of convection in a solid mantle, showing that estimates of its viscosity were several orders of magnitude lower than that required to support flow.

"Radioactivity and Earth movements" , XVII.Trans.Geol.Soc.Glasgow, Vol.XVIII–PartIII, 1931.

"The thermal history of the Earth" .J.Wash.Acad.Sci.23,169–95 1933.

 

In an especially fine piece of work Haskell established the flow viscosity of the mantle, deriving a value that - despite improved observations - remains valid today.

Haskell,N.A. "The viscosity of the asthenosphere" .Am.J.Sci.33,22–8. 1937

 

Gordon then demonstrated that this solid flow was possible through the mechanism of solid state creep and that the observed viscosities were quantitatively consistent with the theory.

Gordon,R.B. "Diffusion creep in the Earth’s mantle". J.Geophys.Res.70,2413–8. 1965

 

I look forward to your response, but urge you follow your head, not your heart if you expect to reach truth.

[creationist]

hi Ophiolite..thank you for responding so quickly...i admire your skills as a debater..you would make a great lawyer..first...in saying my statements are unsubstantiated..neither of us has irefutable proof of our veiws..if so,there wouldnt be any debate..you have the advantage of all the great universities and science books sharing your veiw..but history shows that is no garrenty of correctness..evidence is on both sides of the argument, but its interprted according to the world veiw of the speaker...for instance..Mr Haskells work is great..but he could not know all the possible peramiters involved in the vicosity of the mantle,when he nor anyone else has ever been able to even get one sample of mantle material. Mr Baumgarner has made proably the best effort to date to give a 3D overveiw of subduction, but even his superior mathamatics skill is still just theory. when i said everything above rises..i bookened that with the statement;''this only applies to liquid magma''..of course this would only be magma, when i dont belive the mantle convects at all..i may be wrong,the mantle may convect,but no one has shown conclusivly that it can or does..it is assumed,therefore all uniformatarian papers on the subject will reflect that idea that it does convect..but not all scientsists are uniformatarianists,just as not all scientists are Darwinists..perhaps you could read the petition intitled ''A dissent from Darwin'' all signatures were from respected Phd's in a wide range of scientific disiplines....so are all those guys non scientific because they dont take to the popular worldveiw? its now 10;40..so i will respond to your other objections probably next week...by the way..your points were very good,and do require an answer..when i come back..i will do my best..i only have a high school education..so i cant hope to match your expertise..whitch i will always respect..i love educated people..but i do a lot of studies on my own..and hope to build on that talking to you...if you make i point i cant refute..i will gladly acknowlege it,even the wisest of men are an island of knowlege in an ocean of ignorance..im painfully aware of that in my own life..talk to you soon..your freind,creationist.

[D H]

Wall o' text, man. Some guidelines:

 

Sentences end with one period, not two or three.

The period that ends a sentence needs a space or two after it.

The same goes for a comma.

 

There are these neat little things called blank lines that help separate your ideas.

[Ophiolite]

...in saying my statements are unsubstantiated..neither of us has irefutable proof of our veiws..if so,there wouldnt be any debate..

One cannot prove things in science, only establish the probability at such a level that it would be unreasonable to assign significant doubt.

I do not really see this as a debate, but an educational process. I hope to educate you as to the incorrectness of your beliefs. I acknowledge the possibility that the reverse may occur, but I rather doubt it.

 

you have the advantage of all the great universities and science books sharing your veiw...

No. That is not my advantage. My advantage is that my view is supported by a vast body of interlocking evidence. More to the point I arrived at the view because of the evidence. I didn't start with a viewpoint then try to gather supporting evidence for it.

 

but history shows that is no garrenty of correctness..evidence is on both sides of the argument, but its interprted according to the world veiw of the speaker...

There is very little evidence on the other side of the argument in this case. I have demonstrated that your interpretation of evidence is faulty. For example you claimed solid flow was not possible, that it ran counter to known physical laws. That was simply wrong. If you don't believe solids can flow go stand in front of a glacier.

 

 

Mr Haskells work is great..but he could not know all the possible peramiters involved in the vicosity of the mantle,when he nor anyone else has ever been able to even get one sample of mantle material.

We have tons of samples of mantle material. We have the liquidus derived by partial melting and fractional crystallisation. We have xenoliths in ultrabasic rocks. However, all of that is irrelevant. Haskell determined the viscosity of the mantle by measuring the rate of rebound of Scandinavia following removal of the last ice sheets. This provides absolute values for the mantle viscosity regardless of its composition.

 

 

..i may be wrong,the mantle may convect,but no one has shown conclusivly that it can or does..

Creationist, I really do need to ask that you actually read what I have written. It is almost eighty years since Holmes demonstrated conclusively that the mantle would be convecting. If you wish to deny this you need to do so by finding research work by scientists that demonstrate why it is impossible according to known physical laws. You cannot do this, because no such research exists.

 

Now I do not blame you for difficulty in accepting this. For almost three decades after Holmes work geologists and geophysicists ignored or denied this. However the growing evidence of heat flow (Bullard) gravity anomalies (Meinez) magnetic banding (Vine and Mathews) and the compilation of these and similar observations by the likes of Hess and Dietz and Pinchon led to recognition of its reality.

 

 

..it is assumed,therefore all uniformatarian papers on the subject will reflect that idea that it does convect...

The deabte has been held. The evidence for and against has been reviewed. The conclusion has been reached. Unless and until new evidence is forthcoming, or a radical and elegant reinterpretation of all the data is produced, then that conclusion stands.

 

 

..perhaps you could read the petition intitled ''A dissent from Darwin'' all signatures were from respected Phd's in a wide range of scientific disiplines....so are all those guys non scientific because they dont take to the popular worldveiw?

We are not discussing Darwin. We are discussing plate tectonics. Let's stay on topic.

 

 

..i only have a high school education..so i cant hope to match your expertise..whitch i will always respect..i love educated people..but i do a lot of studies on my own..and hope to build on that talking to you...

And I look forward to sharing such small amounts of knowledge as I have with you. But I shall insist, vigorously and loudly, that when the evidence point to this or that, that it does indeed point there. Arguments that science has been wrong in the past are irrelevant. Arguments that some people disagree are irrelevant. What matters is what does the evidence show?