Register to reply

Plate Tectonics

by PhysicsPost
Tags: plate, tectonics
Share this thread:
davenn
#19
May1-12, 06:35 PM
Sci Advisor
PF Gold
davenn's Avatar
P: 2,651
A closed mind is such a sad thing :( unfortunately you will meet many like that as you go through life

My advantage, like many others, is I never claim to be an expert. That leaves me open to new ideas/ different ways to look at things

do you have any univ. geology studies ? or just a passing interest?


D
Endervhar
#20
May1-12, 07:15 PM
P: 142
In 1983 I started Earth Science with the OU, but my circumstances changed drastically and I stopped at 2 credits. Only recently have I started dabbling a little again. (in geology, not the OU) So I guess that makes me a dabbler, of sorts.
davenn
#21
May1-12, 07:57 PM
Sci Advisor
PF Gold
davenn's Avatar
P: 2,651
Quote Quote by Endervhar View Post
In 1983 I started Earth Science with the OU, but my circumstances changed drastically and I stopped at 2 credits. Only recently have I started dabbling a little again. (in geology, not the OU) So I guess that makes me a dabbler, of sorts.
OU ? which uni is that ?
dont forget we are worldwide on the forum :)


I did my studies at OU = Otago University, Dunedin, NZ

Dave
geo101
#22
May1-12, 08:48 PM
P: 53
Quote Quote by Ophiolite View Post
Well its good to know that my amateur status is also secure. :)
And it is good to know my professional status is very secure! I'm a geophysicist, not specializing in tectonics, but a basic knowledge is useful to say the least

What else was his argument, other than "wrong, wrong, wrong!!"??

I guess he is either one of two groups...
1) Plate tectonics doesn't exist since the world is only 5000 years old
2) The Earth is flat!

[I say this jokingly and mean no disrespect]

A third option does exist, which tentatively supports the idea the Africa is not subducting under Eurasion....

At the moment subduction has largely stalled. And there is some seismic evidence to suggest that a new subduction zone might be forming along the northern coast of Africa (northern Algeria I think). It may be possible that Eurasia will be subducted under Africa.

This was presented at a conference a couple of years ago, but I'm not too sure if it has been published yet. I am not too sure how reliable the data, so I would treat it as an interesting, but still speculative, future possibility.


Endervhar:
The OU, Open University, UK??
davenn
#23
May1-12, 09:14 PM
Sci Advisor
PF Gold
davenn's Avatar
P: 2,651
Quote Quote by geo101 View Post
And it is good to know my professional status is very secure! I'm a geophysicist, not specializing in tectonics, but a basic knowledge is useful to say the least
what's your main field of interest ? I didnt go into geology professionally, am already a full time electronics tech.
I did geol at univ for the pure enjoyment

A third option does exist, which tentatively supports the idea the Africa is not subducting under Eurasion....

At the moment subduction has largely stalled. And there is some seismic evidence to suggest that a new subduction zone might be forming along the northern coast of Africa (northern Algeria I think). It may be possible that Eurasia will be subducted under Africa.
Now that would be an interesting situation where the subduction/ collision zone reverses direction!! Imagine a few volcanoes popping up in nthrn Africa!
Back in my home area, Dunedin, New Zealand was not a subduction area but there was a distinct change in tectonics ~ 5 Ma where it went from extensional with lots of volcanics to collision that produced the Southern Alps that we still see growing today.

Dave
geo101
#24
May2-12, 12:23 AM
P: 53
My focus is magnetics, mainly rock magnetism and paleomagnetism. I don't work on tectonic applications of paleomag, mostly the evolution of the ancient field
Endervhar
#25
May2-12, 07:02 AM
P: 142
"By George, he's got it!" Open University, UK, is what I meant. Sorry to be vague; could I be more insular than I thought? :)

As for the other poster; he is a ferocious supporter of Kevin Mansfield’s “collision” theory. When Pre-Earth and the “old moon” collided Pangaea broke up and the continents moved to their present positions. He tends to present his arguments “loudly” and repetitively in three different threads, so it is easy to avoid actually answering questions.

I am genuinely interested to know how Mansfield’s theory can be supported in the light of modern knowledge, but he seems to assume that anyone who asks questions is a brain washed supporter of plate tectonics. Only recently have there been signs that my persistence may be paying off. One has to walk a delicate line.
geo101
#26
May2-12, 07:44 AM
P: 53
Hah! It is so obscure I had to Google it! Personally I wouldn't waste my time on this. Apparently, Mansfield is a mathematician and a chemist, not an Earth scientist. After a little bit of searching, I'm not sure he is even tenured anywhere.

As for the other poster; he is a ferocious supporter of Kevin Mansfield’s “collision” theory...
Hehe, be careful, you could be up against the man himself!!

You could spend whole days poking holes in his "theory" and backing it up with peer-reviewed and independently verified studies across countless disciplines... paleomagnetism, geochronology, geochemistry, volcanology... and so on.
The point is you will never convince him, he will say it is a large conspiracy. But trust me, scientists like to get the edge on each other and we're always looking to get the next "big story" so it would be a conspiracy that wouldn't last very long!

Have fun running round in circle
geo101
#27
May2-12, 07:48 AM
P: 53
BTW...
No experienced geologist would tell you such rubbish. Your "geologist" is a total amateur
Tell him he can kiss my PhD!
Endervhar
#28
May2-12, 01:12 PM
P: 142
"The inner core grows very slowly over time as material from the fluid outer core solidifies onto its surface. During this process, an east-west hemispherical difference in velocity is frozen into the structure of the inner core."

The above quote is from:
http://www.sciencedaily.com/releases...0220142817.htm

I think I grasped most of this, but I am puzzled by the "east-west hemispherical difference in velocity". This seems to suggest that the two hemispheres are rotating at different rates. I suspect that I am misinterpreting it, as that seems an unlikely scenario.

Please could someone simplify this a bit.
billiards
#29
May2-12, 01:57 PM
P: 748
Quote Quote by Endervhar View Post
"The inner core grows very slowly over time as material from the fluid outer core solidifies onto its surface. During this process, an east-west hemispherical difference in velocity is frozen into the structure of the inner core."

The above quote is from:
http://www.sciencedaily.com/releases...0220142817.htm

I think I grasped most of this, but I am puzzled by the "east-west hemispherical difference in velocity". This seems to suggest that the two hemispheres are rotating at different rates. I suspect that I am misinterpreting it, as that seems an unlikely scenario.

Please could someone simplify this a bit.
I think this is a topic for a new thread.

The difference in velocity refers to the difference in the speed of sound: sound travels faster through one hemisphere (the East) than the other (the West). That is, the inner core exhibits a structure. The authors argue that this structure is incompatible with an inner core that rotates faster (1 deg/year) than the bulk silicate Earth. They study how this structure appears to change with depth, and infer from the known growth rate of the inner core that the inner core is rotating at about 1 degree per million years faster than the bulk Earth.
Endervhar
#30
May2-12, 02:58 PM
P: 142
I think this is a topic for a new thread.
Agreed. I included it here because "the other poster", for brevity, let's call him "P" (for poster, of course, not relief) includes it in his "proofs" of Mansfields theory. The idea is that the collision would have slowed the crust and mantle more than it would have slowed the core.
Endervhar
#31
May3-12, 08:40 AM
P: 142
Geo101, we're slipping towards the ad hominem stuff again in the other forum. The other forum is Science-a-go-go. It lacks the "gravitas" of PF, but I have indicated that I might ask you to give us a look-in rather than relay stuff in both directions. If you do, the thread in which the main activity is concentrated at present is "Proof that PLATE-TECTONICS is WRONG". You would recognise me as Bill S.
geo101
#32
May3-12, 08:31 PM
P: 53
It looks like you are going up against Mr Mansfield himself. You will never convince him. While "preearth" may not give you any of his details, ask about Dr Kevin Mansfield. He has a BSc in mathematics and chemistry, and a PhD in mathematics... where did he get his geology/geophysics degree.

Also, where has this theory been published? I don't recall it being in any published textbooks (I've read quite a few), or having seen in any peer-reviewed scientific journal, why is this?

The general language used in the theory is bad.. "the outer core weighs 9,900 kg/m³"... weight is a measure of force in scientific terms, in common language it often refers to mass, but here he is talking about density, pffft! Sloppy.
Don't tell him this! He will just change it and that may fool others into buying into to his crazy ideas.

There is a reason why I joined PF and not other forums, crackpots like this get shut down! As I said before, no matter how much effort you put into it, how many peer-reviewed articles you throw at him he will never be convinced. You're wasting your time. And that is what I'll stop doing now
davenn
#33
May3-12, 11:09 PM
Sci Advisor
PF Gold
davenn's Avatar
P: 2,651
Quote Quote by Endervhar View Post
Geo101, we're slipping towards the ad hominem stuff again in the other forum. The other forum is Science-a-go-go. It lacks the "gravitas" of PF, but I have indicated that I might ask you to give us a look-in rather than relay stuff in both directions. If you do, the thread in which the main activity is concentrated at present is "Proof that PLATE-TECTONICS is WRONG". You would recognise me as Bill S.
I wouldnt even attempt to argue with him, just a waste of time
An old saying comes to mind.....

"Never argue with a fool. They will drag you down to their level, then beat you with experience! "

cheers
Dave
Endervhar
#34
May4-12, 11:52 AM
P: 142
Thanks for your input and good advice. I know I will never convert Preearth, but I have learned quite a lot from trying get to grips with the theory. Also, I think I am something of a "crackpot" at heart - fortunately I recognise that fact - so I'm reasonably safe on SAGG.
It's good to have somewhere to go for some sanity, though.


Register to reply

Related Discussions
When did plate tectonics begin? Earth 9
Plate Tectonics and Life Earth 11
Plate tectonics Earth 6
Barton vs Chu on Plate Tectonics Current Events 24
Bathymetry, Sediments, and Plate Tectonics assignment Biology, Chemistry & Other Homework 1